Screening tests involve applying simple tests to apparently healthy people to identify those likely to have a disease. An ideal screening test is valid, reliable, and meets specific criteria. Validity is measured by sensitivity, which is the test's ability to detect true positive cases, and specificity, which is its ability to exclude true negative cases. Reliability means the test gives consistent results under the same conditions. Screening can help detect disease early when treatment is more effective, but accuracy is crucial to avoid false positives and negatives. Research carefully evaluates new screening tests against a gold standard to understand their performance.
Social and Preventive Medicine Classroom discussion topic on types of Epidemiological study designs available.
sole reference is Park text book 20th edition
Screening for disease or Early detection of disease is detecting a disease at an earlier stage than would usually occur in standard clinical practice.
This denotes detecting disease at a pre-symptomatic stage, at which point the patient has no clinical complaint ( no symptoms or signs) and therefore no reason to seek medical care for the condition
Early detection of disease is beneficial and that intervention at an earlier stage of the disease process is more effective or easier to implement than a later intervention
The STUDY of the DISTRIBUTION and DETERMINANTS of HEALTH-RELATED STATES in specified POPULATIONS, and the application of this study to CONTROL of health problems."
It gives all the important definitions used in infectious disease epidemiology and continues to elaborate on dynamics of disease transmission followed by prevention and control of infectious diseases.
This PPT discusses
Basics measurements in epidemiology
Basics requirements of measurements
Tools of measurements
Measures of morbidity
Measures of disability
Measures of mortality
The ppt is a short description about how to ascertain the validity, ie; sensitivity and specificity of a screening test as well as their predictive powers. you can also find the technique to ascertain the best possible screening test through the help of an ROC curve...
Screening for Disease (Epidemiology)
Define screening
Describe the aims and objectives of the screening
Describe the differences between Screening & Diagnostic tests
List the uses of screening
Explain the types of screening, criteria for screening
Discuss the Validity of the screening test
Calculate and interpret the evaluation of the screening test
Diagnostic, screening tests, differences and applications and their characteristics, four pillars of screening tests, sensitivity, specificity, predictive values and accuracy
Social and Preventive Medicine Classroom discussion topic on types of Epidemiological study designs available.
sole reference is Park text book 20th edition
Screening for disease or Early detection of disease is detecting a disease at an earlier stage than would usually occur in standard clinical practice.
This denotes detecting disease at a pre-symptomatic stage, at which point the patient has no clinical complaint ( no symptoms or signs) and therefore no reason to seek medical care for the condition
Early detection of disease is beneficial and that intervention at an earlier stage of the disease process is more effective or easier to implement than a later intervention
The STUDY of the DISTRIBUTION and DETERMINANTS of HEALTH-RELATED STATES in specified POPULATIONS, and the application of this study to CONTROL of health problems."
It gives all the important definitions used in infectious disease epidemiology and continues to elaborate on dynamics of disease transmission followed by prevention and control of infectious diseases.
This PPT discusses
Basics measurements in epidemiology
Basics requirements of measurements
Tools of measurements
Measures of morbidity
Measures of disability
Measures of mortality
The ppt is a short description about how to ascertain the validity, ie; sensitivity and specificity of a screening test as well as their predictive powers. you can also find the technique to ascertain the best possible screening test through the help of an ROC curve...
Screening for Disease (Epidemiology)
Define screening
Describe the aims and objectives of the screening
Describe the differences between Screening & Diagnostic tests
List the uses of screening
Explain the types of screening, criteria for screening
Discuss the Validity of the screening test
Calculate and interpret the evaluation of the screening test
Diagnostic, screening tests, differences and applications and their characteristics, four pillars of screening tests, sensitivity, specificity, predictive values and accuracy
Application of a test or a procedure to large number of population who have no symptoms of a particular disease for the purpose of determining their likelihood of having the disease.
Disease screening and screening test validityTampiwaChebani
Full lecture covering screening tests and validity testing. Covers topics such as calculation and interpretation of sensitivity, specificity, positive predictive value and negative predictive value of a screening test.
Screening of Diseases_Community Medicine
Slides may be referred by both undergraduate and postgraduate students and anyone affiliated to Public health.
Any comments or doubts may be addressed to vineeta1992@gmail.com
Screening is an essential concept in the field of Medicine, specially in Preventive Medicine. This presentation covers the essentials to understand Screening of Diseases.
Evidence based medicine is now focusing on diagnostic tests: how accurate and useful could be ? sensitivity and specificity are no longer the important criteria for a test
Screening is defined as the search for unrecognized disease or defect by means of rapidly applied tests , examinations or other procedures in apparently healthy individuals
Epidemiological method to determine utility of a diagnostic testBhoj Raj Singh
The usefulness of diagnostic tests, that is their ability to detect a person with disease or exclude a person without disease, is usually described by terms such as sensitivity, specificity, positive predictive value and negative predictive value (NPV). Many clinicians are frequently unclear about the practical application of these terms (1). The traditional method for teaching these concepts is based on the 2 × 2 table (Table 1). A 2 × 2 table shows results after both a diagnostic test and a definitive test (gold standard) have been performed on a pre-determined population consisting of people with the disease and those without the disease. The definitions of sensitivity, specificity, positive predictive value and NPV as expressed by letters are provided in Table 1. While 2 × 2 tables allow the calculations of sensitivity, specificity and predictive values, many clinicians find it too abstract and it is difficult to apply what it tries to teach into clinical practice as patients do not present as ‘having disease’ and ‘not having disease’. The use of the 2 × 2 table to teach these concepts also frequently creates the erroneous impression that the positive and NPVs calculated from such tables could be generalized to other populations without regard being paid to different disease prevalence. New ways of teaching these concepts have therefore been suggested.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
2. SCREENING tests :
DEFINITION
Is the application of relatively simple and rapid test to a
large number of apparently healthy people in order to
classify them as likely or unlikely to have the disease.
Screening: Considered a secondary preventive
intervention
3. • Assessing a new diagnostic test is done versus an
accepted reference test known as “gold
standard”. By this gold standard individuals are
labeled as either diseased or free.
• Then, sensitivity, specificity, predictive value of
positives & predictive value of negatives can be
calculated for the new test.
Researches to study the performance of a diagnostic
test
“ screening test’’
4.
5. -Disease/disorder should be
An important public health problem
High prevalence
Serious outcome
-Early Detection in a symptomatic (pre-clinical)
individuals is possible
-Early detection and treatment can affect the
course of disease (improve outcome)
-Effective ttt is available for the detected disease.
- Screening tests are simple, acceptable to population, inexpensive,
noninvasive, not painful, and relatively accurate
Criteria for Use of a Screening Test
7. Special requirements of Screening Tests
A-Valid: ability of the screening test to do
what is supposed to do. Measured by;
–Sensitivity: ability to detect +ve cases among
truly +ve
–Specificity: ability to detect –ve cases among
truly –ve
– Positive Predictive Value: proportion testing positive
who actually have the disease
– Negative Predictive Value: proportion testing negative
who do not have the disease
8. Special requirements of Screening Tests
b-Reliable: It is the ability of the test to give
same results when repeated under standard
conditions.
9. Group (a(
True Positive
Group (b(
False Positive
Group (c(
False Negative
Group (d(
True Negative
The 2x2 Table describes screening test outcomes:
Disease
present
Disease
absent
Positive result
Negative result
Application of Screening to
Populations
Diagnostic test or gold standardScreening test
10. Group (a(
True Positive
Group (b(
False Positive
Group (c(
False Negative
Group (d(
True Negative
Characteristics of Screening
Tests
1) Sensitivity: proportion of those with disease
who test positive in the screened group
(a)
(a) + (c)
Positive
result
Negative
result
Disease
present
Disease
absent
Total
11. Group (a(
True Positive
Group (b(
False Positive
Group (c(
False Negative
Group (d(
True Negative
Characteristics of Screening
Tests
2) Specificity: proportion of those without disease who
test negative in screened group
(d)
(b) + (d)
Positive
result
Negative
result
Disease
present
Disease
absent
Total
12. 200
True positive
0
False positive
0
False negative
800
True negative
Disease
present
Disease
absent
Positive
result
Negative
result
n = 200 n = 800
The Ideal Situation--100%
Agreement
14. 3) Positive Predictive Value (PPV): The
likelihood that a positive test result indicates
the presence of the disease
(a)
(a) + (b)
Characteristics of Screening
Tests
Group (a(
True Positive
Group (b(
False Positive
Group (c(
False Negative
Group (d(
True Negative
Positive result
Negative result
Disease
present
Disease
absent
Total
15. 4) Negative Predictive Value (NPV): The
likelihood that a negative test result
indicates the absence of the disease
(d)
(c) + (d)
Characteristics of Screening Tests
Group (a(
True Positive
Group (b(
False Positive
Group (c(
False Negative
Group (d(
True Negative
Positive result
Negative result
Disease
present
Disease
absent
Total
16. Criteria for Evaluating a Screening
Test
•Validity : provide a good indication of who does and does
not have disease
-Sensitivity of the test
-Specificity of the test
•Reliability=reproducibility=precision : gives
consistent results when given to same person under the same
conditions
‘’Agreement within and between examiners’’
17. Validity of Screening Test (Accuracy)
- Sensitivity: Is the test detecting true cases of
disease? (Ideal is 100%: 100% of cases are
detected)
-Specificity: Is the test excluding those without
disease? (Ideal is 100%: 100% of non-cases are
negative)
18. • Advantages
• Disadvantages
Screening test
Gold standard test
test diseased healthy Total
positive a b a + b
negative c d c + d
Total a + c b + d a + b + c + d
19. Advantages:
Magnitude of disease can be precisely
assessed, where pre-symptomatic cases are
not missed.
Early detected cases can be effectively
controlled, with better prognosis, no or
minimal consequences and less burden on
health services.
Screening test
20. Disadvantages:
Not 100% accurate test. Detected cases may
be actually free of the disease (called false
positive), on the other hand the test may
diagnose actually diseased persons (false
negative). The higher the percentages of
false positive and false negatives the worse
is screening test.
Screening test
21. 1-Mass screening:
Large numbers of people are screened for
the presence of a disease without specific
reference to their individual risk of having
or developing the condition. As screening
for type 2 DM in certain community.
Types of Screening program
22. 2-Selective screening: They are used to
detect specific disease in people who are
known to be at high risk.
e.g. screening for bone thickness among
females at menopause, type 2 DM in obese
persons, chest X-ray for males heavy
smokers with chronic cough.
Types of Screening program cont.
23. 3-Opportunistic screening: Applied when
the opportunity arises as for example in pre-
placement examination, examination of
students at school entry and soldiers who
join the army by general clinical
examination, urine and stool analysis, blood
picture, dental examination and visual
acuity
Types of Screening program cont.
24. • Exercise .
A medical research team conduct a trial to
find if high plasma level of breast carcinoma
promoting factor (BCPF) could be used to
diagnose breast cancer.
• Out of 1600 patients included in the study,
600 demonstrated by breast biopsy (the gold
standard) to have breast cancer (D+) and
1000 were found to be disease –free(D-)
• Out of the 600 demonstrated to have breast
cancer, 570 were positive by BCPF(T+) and
Out of the 1000 were found to be disease –
free, 850 were negative by BCPF(T-)
25. Feedback of Exercise .8:- It is an example of studying
the performance of a new diagnostic test
PATHOLOGY
STUDIED
TEST
Breast
cancer(D+)
No breast
cancer (D-)
Total
Marker (+)
(T+)
570 (TP) 150 ( FP) 720
Marker (-)
(T-)
30 (FN) 850 (TN) 880
Total 600 1000 1600
26. • Feedback of Exercise .8(cont.):-
• Sensitivity, specificity, predictive value positive &
predictive value negative can be calculated
• Sensitivity= 570/600 = 0.95 = 95%
• Specificity=850/1000 = 0.85 = 85%
• Predictive value positive= 570/720 = 0.79=79.2%
• Predictive value negative= 850/880 = 0.97=96.6%
27. Remember Steps in the
Research Process
1.Define the Problem
2. Review the literature
3-Conduct research on the problem.
4. Define the population
5-clearly define terms & concepts
28. Steps in the Research Process
6. Conduct experiments, collect data.
7-Analyze the data
8. Present the results
9-Dissemination.