Study Designs in Health Research

Forensic Science

• Forensic science is the application of scientific methods and techniques to legal issues.
• Locard's Principle: Every contact leaves a trace.
• Trace evidence is small amounts of material linking a crime scene to a suspect. Examples include glass, fibers, and paint.

Forensic Analysis Techniques

• Glass analysis involves analyzing the physical and chemical properties of glass fragments.
• Microscopic examination is essential for identifying and comparing trace evidence.
• Chromatography and spectroscopy are used to analyze the chemical composition of substances.
• Blood pattern analysis investigates the patterns of bloodstains to understand the sequence of events during a crime.
• Preliminary tests for semen can include microscopy, acid phosphatase analysis, and p30 tests.
• Preliminary saliva tests may utilize starch/iodine reactions or salivary amylase tests.

Pharmacogenetics

• Pharmacogenetics investigates how genes influence the absorption, distribution, metabolism, and elimination of drugs (ADME).
• Pharmacodynamics studies what a drug does to the body.
• Pharmacokinetics studies how the body processes a drug.
• Absorption of alcohol includes processes in the mouth, esophagus, stomach/small intestine, and the circulatory system.
• Distribution of alcohol occurs proportionally to the water content of various body compartments.
• Alcohol metabolism occurs in the liver (90%). Ethanol is converted to acetaldehyde, then to acetic acid, with byproducts being carbon dioxide and water.

Blood Alcohol Concentrations

• Blood alcohol concentration (BAC) is the most accurate measure of alcohol in the body.
• Legal limits for alcohol vary per region (e.g., England, Scotland, Wales).
• Biochemical analysis of alcohol involves enzymatic steps (e.g., alcohol dehydrogenase).
• Chemical analysis of alcohol uses breathalyzers.
• Absorption time can be affected by food intake.

Entomology in Forensic Science

• Entomology studies insects.
• Post-Mortem Interval (PMI) is the interval between death and examination.
• Factors like temperature, decomposition process, insect colonization patterns, and succession patterns are crucial for estimating PMI.
• Insect activity is influenced by environmental temperature and may vary across locations.
• Stages of decomposition include fresh, bloat, putrefaction, and dry stages.

Extreme Biology

• Extreme biology studies organisms living in extreme conditions (e.g., high temperature, pressure, salinity, radiation).
• Bacteria are ubiquitous.
• Bacteria can adapt to extreme environments by changing their ribosomal abundance, protein synthesis parameters, and membrane lipids.
• Thermophiles thrive at high temperatures.
• Psychrophiles tolerate cold temperatures.
• Xerotolerants endure dry conditions.
• Alkaliphiles live in alkaline environments.
• Acidophiles live in acidic environments.

Extreme Adaptations

• Organisms can use heat exchangers for effective heat exchange, eg a counter-current system in duck legs.
• Antifreeze proteins and glycerol can protect organisms, preventing ice crystal growth.
• Regional heterothermy and torpor help maintain core body temperature for an organism in fluctuating temperatures.
• Adaptive mechanisms for osmotic regulation help maintain water balance in extreme environments.
• Some organisms can survive drought conditions via spore formation and extracellular polymeric substance synthesis.

One Health

• One Health is a cross-cutting framework spanning multiple sustainable development goals (SDGs).
• One Health prioritizes human health, animal health, and environmental health, focusing on the interactions.
• One Health links overconsumption to environmental health challenges.
• Many emerging human pathogens have a zoonotic origin (e.g., COVID-19).
• Surveillance for infectious zoonotic diseases is an essential public-health activity.

Extreme Environments and Human Health

• Extreme altitudes (higher than 5500m) present hypoxic conditions, impacting bodily functions like respiration and circulation.
• Altitude sickness affects humans due to decreased partial pressure of oxygen at higher altitudes.
• Acclimatization to high altitudes involves processes that increase oxygen-carrying capacity in blood as an adaptation to the stressful environment.
• Pressure, temperature, and altitude factors have significant impacts on organism physiology and human health.

Mpox

• Mpox is a zoonotic infection with an unknown animal reservoir.
• A large outbreak has been observed in 2022.
• Mpox has a characteristic pattern, including a rash that progresses through stages. Infection proceeds from papules to vesicles to pustules and to scabs.
• Mpox diagnosis involves determining the viral clade present.
• Mpox treatment utilizes monoclonal antibodies, with combination therapy used to limit drug resistance. Live-attenuated vaccines (similar to smallpox vaccines) are being used for prevention.

Infectious Diseases

• Infectious diseases continue to emerge and re-emerge in populations due to many factors, including environment, bioterrorisms, accidents in laboratories, and human travel.
• Transmission modes vary (e.g., vertical, horizontal, vector-borne, foodborne).
• Surveillance is crucial for managing and controlling infectious disease outbreaks.
• Effective interventions are necessary to prevent infectious diseases from spreading.

DNA Profiling

• DNA profiling uses genetic markers (STRs and SNPs) for identification.
• DNA profiling is useful in forensic contexts and for disaster relief cases.
• Databases (e.g., CODIS) exist to aid matching or identifying suspects via DNA.
• Techniques like RFLP and PCR are used for DNA analysis.

Surveillance of Infectious Diseases

• Surveillance is ongoing, systematic collection, analysis, and interpretation of health-related data regarding disease and disease prevalence.
• Types of surveillance include active, targeted, and passive surveillance.
• "Citizen science" can be part of surveillance initiatives in collecting and reporting observations.
• Epidemiological Triad considers the host, agent, and environment.

This quiz explores various study designs used in health research, focusing on their strengths, limitations, and specific applications. Delve into concepts such as incidence comparison, descriptive studies, and ecological studies, while discovering the life cycle of the Lancet fluke. Test your understanding of observational studies and their role in establishing causal relationships.