The document discusses various models of aging at both the individual and non-individual level. It describes several key models including: mechanistic aging which focuses on damage at the cellular/DNA level; organismal aging which takes a holistic view of cellular aging effects; contextual aging which considers social/environmental factors; mouse models which are useful mammalian models; yeast models including replicative and chronological lifespan studies; cellular models which examine finite cell division capacity; and the decremental model which views decline as inevitable with age. The models provide insights into aging mechanisms but also have limitations in representing all species.
This presentation covers the different types and mechanisms of regeneration ranging from hydra, salamanders and mammals. With more emphasis on physiology and genetics, this presentation explains epimorphosis and morphallaxis in different organisms. Hope you will get enough information from the slides about SCD. (This is a presentation that was done with the help of my classmate Bollam Haripriya, initially for her class presentation.)
This presentation provides an overview of Cell senescence, Aging, Theories of Aging,principle of senescence, Mechanism of action, Factors, Diseases caused due to this action, Senescence and cancer, Insulin signalling cascade, Telomere shortening.
hox genes and its role in development both in human and drosophila . homeotic genes. homeobox genes. developmental biology. different types of homeotic genes in drosophila and human. deficiencydiseases due to lack of hox genes in human
This presentation covers the different types and mechanisms of regeneration ranging from hydra, salamanders and mammals. With more emphasis on physiology and genetics, this presentation explains epimorphosis and morphallaxis in different organisms. Hope you will get enough information from the slides about SCD. (This is a presentation that was done with the help of my classmate Bollam Haripriya, initially for her class presentation.)
This presentation provides an overview of Cell senescence, Aging, Theories of Aging,principle of senescence, Mechanism of action, Factors, Diseases caused due to this action, Senescence and cancer, Insulin signalling cascade, Telomere shortening.
hox genes and its role in development both in human and drosophila . homeotic genes. homeobox genes. developmental biology. different types of homeotic genes in drosophila and human. deficiencydiseases due to lack of hox genes in human
Aging is a natural phenomenon. it is the law of nature
this slide is about the various factors which independently or in combinations contribute to aging in humans
How 3 germ layers are formed in Chick that are endoderm, mesoderm and ectoderm.As Chick are polylecithal so cell movements are somewhat restricted and gastrulation is modified as compared to frog.
Describes the process of ageing in cells, factors affecting cells like telomere, free radicals, oxidative stress, DNA damage, environmental factors, proteostasis, mitochondrial disfunction etc are described
Introduction
About Drosophila
Genome of Drosophila
Life cycle
Differentiation
Development of Drosophila
* Embryonic development
* Dorsal -ventral and
* Anterior posterior development
* Body segmentation
* Homeotic gene
Conclusion
Reference
It is about aging and how aging is tried to controlled by different sort of methods and animals models are used in the testing the products created by science. It explains the different theories of aging in a very detailed manner. And the very least includes different animal models like mouse and monkey on which these treatments are applied and checked the effects of them that how we can control aging. We, can never say that controlling aging is something about that we are becoming immortal it is totally about finding the factors which can reduce tha aging and aging related diseases.
Aging is a natural phenomenon. it is the law of nature
this slide is about the various factors which independently or in combinations contribute to aging in humans
How 3 germ layers are formed in Chick that are endoderm, mesoderm and ectoderm.As Chick are polylecithal so cell movements are somewhat restricted and gastrulation is modified as compared to frog.
Describes the process of ageing in cells, factors affecting cells like telomere, free radicals, oxidative stress, DNA damage, environmental factors, proteostasis, mitochondrial disfunction etc are described
Introduction
About Drosophila
Genome of Drosophila
Life cycle
Differentiation
Development of Drosophila
* Embryonic development
* Dorsal -ventral and
* Anterior posterior development
* Body segmentation
* Homeotic gene
Conclusion
Reference
It is about aging and how aging is tried to controlled by different sort of methods and animals models are used in the testing the products created by science. It explains the different theories of aging in a very detailed manner. And the very least includes different animal models like mouse and monkey on which these treatments are applied and checked the effects of them that how we can control aging. We, can never say that controlling aging is something about that we are becoming immortal it is totally about finding the factors which can reduce tha aging and aging related diseases.
this slides contain about the detailed information about the definition, introduction, classification, types, concept of aging, chronologic aging, biological aging, psychological aging, social aging, cognitive aging.
Basic of geriatrics and internal medicine for physiotherapistDoha Rasheedy
collection of lectures for physiotherapy undergraduate students including notes of common health issues (frailty, sarcopenia, osteoporosis, neuropsychiatric issues, constipation, metabolic syndrome and its components, orthostatic hypotension, CLD, CKD, anemia, immobilization, dizziness, falls, fatigue) and how to handle in practice.
summary of age related changes and geriatric pharmacology, safe analgesic prescription in elderly
Aging vs agings: limits and consequences of biomedical definitionsattilacsordas
Talk given by Attila Csordas on a joint Philosophy of Science, Mathematics and Logic PhD Seminar at the Institute of Philosophy at Eötvös University, Budapest, October, 2019
http://phil.elte.hu/tpf/2019-2020/October/
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
NVBDCP.pptx Nation vector borne disease control program
Aging and model of aging
1. Modelsof aging| Molecularbiology2
1
Table of content
Introduction
Individual model
Non individual model
Selection of Model Sytem
Mouse model of aging
Decremental model of aging
Yeast model of aging
Cellularmodel of aging
Characteristics model of aging
2. Modelsof aging| Molecularbiology2
2
MODELS OF AGING
AGING:-
The process of becoming older, a process that is genetically determined
and environmentally modulated.
Models of aging:-
The models are characteristerized in two models
1- Individual model
2- Non individual models.
1 - Individual Models:-
With individual models of aging, we focus on the individual person
. Mechanistic aging, sometimes referred to as the biological model, is broadly
defined as damage at the cellular level or DNA level results in accumulation of
mutations or incompetent cells.because biologists have focused on specifics in
different areas, like DNA, mitochondria, and free radicals.
Mechanistic aging states that as you get older your cells run into problems - maybe
as one was dividing the DNA got all jumbled, and now the cells that divided from
it don't work as well as before; or something got into the cell's mitochondria, which
helps power the cell, and damaged that. Now the cell is working on half the juice it
should. These accumulate and result in inefficient areas in the body, like the skin
not being as elastic or the heart growing weaker.
Organismalaging:-
is defined as a holistic view of an individual based on cellular
aging. With mechanistic, we look at the specific cells and how they work. With
organismal, we are seeing how they come together. So mechanistic is sort of
3. Modelsof aging| Molecularbiology2
3
subsumed by organismal because organismal focuses on the whole organism rather
than the individual parts.
One idea behind organismal aging is that there is a limit on the number of times a
cell can divide. Every organ is made up of cells, and many of them are repaired by
dividing cells. If they reach that limit, then they can no longer divide, and now the
organ is working with fewer and fewer cells. This is kind of like running a big fleet
of cars, and in the beginning you have 100 mechanics, and by the end, you have
one or two.
2-Non-Individual Models:-
Contextual aging:-
is defined as a description of a person's social and
environmental factors. This is you 'not acting your age.' Age doesn't necessarily
mean one has to act a certain way. However, society demands that people of a
certain age act a certain way.
Selection of model system:-
• Species lower on the phylogenetic scale, such as fish and mice, are effective
models for the study of basic mechanisms of aging .
• species commonly used for aging research, it is crucial to be aware of
physiological and behavioral differences associated with varying genetic
background, environment, and other factors to ensure appropriate model
selection.
Mouse model of Aging
Much has been learned from the study of aging in worms and flies, but it is
important to test the knowledge derived from these lower organisms in a
mammalian species. For this, the mouse is ideal. Not only does it have a relatively
short lifespan but, as a mammalian research model that shares 99% of its genes
with humans.
4. Modelsof aging| Molecularbiology2
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Mice and rats are favorite subjects of scientists interested in human aging. Because
they are mammals, they are more closely related to us than yeast, flies, or worms,
and their relatively small size and short life span make them easier to study than
long-lived animals.
1-Metabolic Stability
The concept of metabolic stability was originally introduced in an analytic theory
of longevity to provide a molecular mechanism for the large variation in life span
observed between species. Metabolic stability, roughly speaking, describes the
capacity of the metabolic network to maintain steady-state values of redox couples
in response to random perturbations in the rates of enzymatic processes. The
significance of this concept in studies of aging resides in the metabolic stability-
longevity principle. This asserts that metabolic stability is the prime determinant of
the rate of aging and is positively correlated with the maximal life-span potential of
a species. Accordingly, strongly stable networks will be defined by slow rates of
aging, whereas weakly stable networks will be defined by rapid rates of aging.
Senescence is the result of spontaneous changes in the metabolic condition of the
cell during normal development. Studies consistent with are the empirical
investigations show that ATP/AMP ratio, a metabolic marker of stability,
decreases with age and that organisms with a larger ATP:AMP ratio live longer.
2-Calorie Restriction
Calorie Restriction increases longevity by increasing the metabolic stability of the
regulatory networks. We can therefore infer that, in the case of humans, a species
close to the condition of maximal metabolic stability, DR will have negligible
effect on stability, and hence no effect on maximum life span. However, DR may
have an effect on mean life span. Mean life span is simply a measure of our ability
to minimize premature death. DR (Dietary Restriction) can influence mean life
span by simply reducing the incidence of diseases suchas diabetes, atherosclerosis,
and hypertension. These changes, however, will result in an increase in life span of
only about 3–5 years—a moderate effect. Since DR will have a negligible effect on
metabolic stability, it will exert no effect on the rate of aging and hence induce no
changes in the human senescence process.
3-Oxidation Stress
5. Modelsof aging| Molecularbiology2
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In mice, interventions that enhance oxidative damage generally shorten lifespan
metabolic activities that sustain life also create “metabolic stress,” which, over
time, results in damage to our bodies. Take breathing—obviously, we could not
survive without oxygen, but oxygen is a catalyst for much of the damage
associated with aging because of the way it is metabolized inside our cells. Tiny
parts of the cell, called mitochondria, use oxygen to convert food into energy.
While mitochondria are extremely efficient in doing this, they produce potentially
harmful by-products called oxygen free radicals. The accumulation of oxidative
(free radical) damage in our cells and tissues over time might be responsible for
many of the changes we associate with aging. Free radicals are already implicated
in many disorders linked with advancing age, including cancer, atherosclerosis,
cataracts, and neurodegeneration.
4-Mutations
Mutations that extend lifespan are likely to affect the rate of aging, while those that
reduce lifespan either alter aging or increase the risk or severity of a particular
disease. According to Mouse Genome Informatics 301 mutations decrease survival
by causing or promoting susceptibility to disease and 46 promote features of
premature aging. In Table we list genes whose mutations decrease longevity and
appear to alter aging. The roles of these genes, similar to the mutations that extend
longevity, suggest that maintaining DNA stability and antioxidative stress are
important molecular mechanisms that regulate aging and longevity. For example, a
knockout of Bub1b induces chromosome (Chr1) instability, reduced expression of
PolgA increases mutations in mitochondrial DNA, and knockouts of Msra and
Prdx1 increase oxidative stress.
6. Modelsof aging| Molecularbiology2
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The growing interest in mouse aging and genetics has been strongly stimulated by
the sequencing of the mouse and human genomes and by the realization that most
human genetic diseases can be modeled by changes in equivalent genes in these
rodents. The fact that aging can be slowed by dietary or genetic changes in mice is
fueling new enthusiasm for the use of this model mammal as a guide to human
aging
Decremental model of aging:
• Many of our attitudes about aging are based on a decremental model of
aging, which holds that progressive physical and mental decline is inevitable with
age. In other words, chronological age is what makes people “old.
Attitude towards aging:
The prevalence of the decremental view in our society can be explained in
part by ignorance and a lack of contact with older people.
The result is a climate of prejudice against the old.
A researcher coined the word ageism to refer to this prejudice.
Young people tend to believe that the old suffer from poor health, live in
poverty, and are frequent victims of crime. Such beliefs, however, affect
stereotypes of the elderly.
Changes in health:
Most people over 65 are in reasonably good health; of course, physical
strength and the senses do decline.
About 40 percent of the elderly have at least one chronic disease.
The quality of health care for the elderly remains by and large inferior to that
of the general population.
7. Modelsof aging| Molecularbiology2
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Changes in life situation:
For younger people, transitions in life–graduation, marriage, parenthood–are
usually positive and create a deeper involvement
In late adulthood, transitions–retirement, widowhood–are often negative and
reduce responsibilities and increase isolation.
The symptoms of depression are very common in older adults. On the positive
side, older people continue to learn and develop skills more than ever before.
Changes in mental functioning:
As people age, there are also changes in many of the mental functions they use,
although there is much less decline in intelligence and memory than people think.
John Horn (1982) has proposed two types of intelligence:
Crystallized intelligence–the ability to use accumulated knowledge and learning in
appropriate situation.
Fluid intelligence–the ability to solve abstract relational problems and to generate
new hypothesis.
Senile dementia:
A small percentage of people develop senile dementia in old age. Senile dementia
is a collective term that describes conditions characterized by memory loss,
forgetfulness, disorientation of time and place, a decline in the ability to think,
impaired attention, altered personality, and difficulties in relating to others.
Alzheimers disease:
The most common form of senile dementia is Alzheimer’s disease Alzheimer’s
disease is an affliction more commonly seen among the elderly. Alzheimer’s is a
neurological disease marked by a gradual deterioration of cognitive functioning.
The causes of Alzheimer’s are complex and still not completely understood.
Genetic susceptibility plays a role.
8. Modelsof aging| Molecularbiology2
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At present there is no cure.
Cellular model of aging:
Cellular aging is the decrease in the cell's ability to
proliferate with the passing of time. Each cell is programmed for a certain number
of cell divisions and at the end of that time proliferation halts. The cell enters a
quiescent state after which it experiences CELL DEATH via the process of
APOPTOSIS.
Factors effecting in aging process and functional relationship between them:
Hallmarks:
Genomic instability, telomere attrition, epigenetic alterations,
loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction,
cellular senescence, stem cell exhaustion and altered intercellular communication.
At cellular levels, age-dependent declines can arise from the accumulation of
damage and erosion to cellular macromolecules including proteins, RNA and
DNA, usually a result of cellular stress and environmental insults.
Of these, DNA damage accrual and insufficient DNA repair often accompanied by
oxidative stress and mitochondrial dysfunction is a principal factor contributing to
cell senescence and aging.
9. Modelsof aging| Molecularbiology2
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Conversely, DNA repair pathways delay cell senescence and aging by
maintaining genomic integrity.
Telomerase theory of aging:
• Telomeres are…
Repetitive DNA sequences at the ends of all human
chromosomes.They contain thousands of repeats of the six-nucleotide sequence,
TTAGGG .In humans there are 46 chromosomes and thus 92 telomeres (one at
each end) .Senescent cells have shorter telomeres .length differs between species
.In humans 8-14kb long .Telomere replication occurs late in the cell cycle.
Once the telomere shrinks to a certain level, the cell can no longer
divide. Its metabolism slows down, it ages, and dies. Telomerase (enzyme that
extends telomere) works by adding back telomeric DNA to the ends of
chromosomes, thus compensating for the loss of telomeres that normally occurs as
cells divide. Most normal cells do not have this enzyme and thus they lose
telomeres with each division. Shorter telomeres have a negative effect on our
health.
Telomere shortening is the main cause of age-related break down of our
cells.When telomeres get too short, our cells can no longer reproduce, which
causes our tissues to degenerate and eventually die. Some cells, like those found in
the skin, hair and immune system, are most affected by telomere shortening
because they reproduce more often
Yeast Model system of aging
The budding yeast Saccharomyces cerevisiae is a widely used model of cellular
and organismal aging. The first studies of yeast aging were published over 50 years
ago, in which yeast cells were shown to have a finite replicative capacity
Replicative life span was thus defined as the number of daughter cells produced by
a mother cell before senescence. A second model of aging has more recently been
developed in yeast, termed chronological aging. In contrast to replicative life span
(RLS), chronological life span (CLS) is defined as the length of time a yeast cell
can survive in a no dividing state. These two models for aging in yeast provide a
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unique opportunity to compare and contrast the aging processes of both
proliferating and nonproliferation cells in a simple single-celled organism
The two lifespans of yeast. The metric of replicative lifespan is the number of
mitotic divisions a mother cell (M) undergoes before senescence, this being also
the number of daughter cells (D) that it produces. The metric of chronological
lifespan is the length of time that a stationary phase cell remains viable under
defined conditions of maintenance, viability being measured as its capacity to re-
enter the mitotic cell cycle when supplied with nutrients.
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Ageing and longevity
‘Ageing’ is a process — a functional decline that is essentially a by-product of
natural selection operating to achieve the optimal balance of the available
resources between the competing priorities of somatic maintenance and
reproduction. ‘Longevity’, in contrast, is a parameter — the length of time that
individuals will remain alive in the absence of death from extrinsic causes, this
being inversely proportional to the pace at which ageing occurs. ‘Ageing’ and
‘longevity’ are terms that are frequently used interchangeably.
Apoptosis and oxidative stress
Yeast apoptosis and aging remains correlative, but highly intriguing. Both
replicative and chronologically aged cells show markers consistent with apoptotic
death . At present, however, it remains unclear whether there exists a causal
relationship between apoptosis and senescence in yeast. It has been reported that
deletion of the yeast caspase YCA1 results in an increase in chronological
longevity, but only after the culture falls below 10% viability. This suggests that
apoptosis exerts an effect on longevity only after the majority of cells have already
undergone senescence. Thus, for most cells in the population, activation of the
apoptosis-like pathway may be a response to the damage leading to senescence.
The observation that apoptotic markers are present in both replicative and
chronologically senescent cells may be an indication that the ultimate cause of
senescence is similar in both dividing and nondividing yeast cells. This would be
consistent with the finding that chronologically aged cells have a reduced RLS and
that some interventions (e.g., DR or reduced target-of-rapamycin (TOR) signaling)
increase both RLS and CLS.
Characteristics of model organism
Model organisms are usually chosen for reasons of convenience. Depending on the
type of research performed, common characteristics tend to include:
Small Size
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Rapid Generation Time
Easy Upkeep
Easy Experimentation: in genetics, and ideal model organism is
transformable, there are techniques to isolate nucleic acids, etc.
High Volume of Background Information
Disadvantages of model organism
The general disadvantages are:
1. Your model may not be truly representative of similar species. Example- Plant
geneticists use Arabidopsis thaliana as a model, however as plants go Arabidopsis
has an abnormally small genome, and comparatively little repetitive DNA.
2. Genetic Variance. When doing certain types of studies your data might vary
because there is natural genetic variance in a population. This can be overcome by
using inbred lines that have low genetic variability which can make your results
more consistent.
3. Background Knowledge. It's not always possible to use a model that has
extensive background information. Many genomes have been sequenced. If you
use a model that has not been sequenced you are limited as to what types of
experiments you can do (or you are forced to do extensive preliminary
experiments).
4. Transfer of Methodology. Techniques used in your model may only work in
your model and will not work in other species. This also includes applications like
statistics.
5. Lack of Methodology. You may wish to perform certain types of experiments,
however it may not be possible. For example efficient targeted gene removal is
currently not possible in plants. To properly characterize a gene you should look at
a null mutant, however this is not always possible.