11 January 2010

Male Obesity and Semen Analysis Parameters



Male Obesity and Semen Analysis Parameters
By:Joseph Petty, MD
Samuel Prien, PhD
Amantia Kennedy, MSIV
Sami Jabara, MD

Background: Obesity

* Obesity is a growing problem.
* The Behavioral Risk Factor Surveillance System, in conjunction with the CDC, conducted a national survey and found that in 2000, the prevalence of obesity (BMI >30 kg/m2) was 19.8%, a 61% increase since 1991.
* Obesity affects female and male fertility.
* In a study comparing IVF success rates and female obesity, it was shown that a 0.1 unit increase in waist-hip ratio led to a 30% decrease in probability of conception per cycle 2.
* In couples complaining of infertility, male factor plays a role in up to 40% of cases.

Background: Semen Parameters
* What parameters best predict fertility?
* National Cooperative Reproductive Medicine Network: 765 infertile couples (no conception after 12 months), and 696 fertile couples
* greatest discriminatory power was in the percentage of sperm with normal morphologic features.

Hypothesis
* Since there is an observed correlation between obesity and male factor infertility, our hypothesis is that an increased BMI is associated with higher rate of abnormal semen parameters, especially sperm morphology.

Recent Studies
* Danish study by Jensen et al. enrolled 1,558 young men (mean 19 years old) when they presented for their compulsory physical exam as part of their country’s military drafting system.
* The authors showed decreased sperm counts and concentration (39 million/mL vs. 46million/mL) in those with an elevated BMI (>25kg/m2). They did not, however, observe a difference in morphology.
* Hormonal differences
* Kort et al. looked at semen analysis results in 520 men
* grouped according to their BMI, and measured the average normal-motile-sperm count (NMS = volume x concentration x %motility x %morphology)
* Kort concluded that men with high BMI values (>25) present with few normal-motile sperm cells
* Hammoud et al., showed a increased incidence of oligospermia and increased BMI and also showed decreased levels of progressively motile sperm
* Considered each parameter separately.

Sexual function
* Agricultural study: The association between BMI and infertility was similar for older and younger men, disproving the theory that erectile dysfunction in older men is a significant factor.
* Hammoud et al., though primarily concerned with hormones, looked at erectile dysfunction directly and showed that there was no correlation with increases in BMI
* Nguyen et al., effect of BMI is essentially unchanged regardless of coital frequency, suggesting that decreased libido in overweight men is not a significant factor

Hormonal Profile
* Danish study, observed decreased FHS and inhibin B levels in the obese.
* Pauli et al., observed with increases in BMI a decreased total T, decreased SHBG, increased estrogen and decreased FSH and inhibin B.
* Inhibin B, cited for its usefulness as a novel marker for spermatogenesis and its role in pituitary gonadotropin regulation.
* Pauli: no correlation of BMI or skinfold thickness with semen analysis parameters, though it was observed that men with proven paternity versus those without had lower BMI.

Interventions: Gastric Bypass

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07 January 2010

Management of Radiation Accident victim



Physician and Hospital Responses to Radiological Incidents
By: Robert E Henkin, MD, FACNP, FACR
Professor of Radiology
Director, Nuclear Medicine

Robert H. Wagner, MD, MSMIS
Associate Professor of Radiology
Section on Nuclear Medicine/Department of Radiology
Loyola University
Maywood, IL

Experience of Authors

* Dr Wagner trained at Loyola and the DOE in Oak Ridge - Radiation Emergency Assistance Center/Training Site (REAC/TS)
* Drs Wagner and Henkin co-wrote the original manual for hospital management that was used by the State of Illinois
* Dr Wagner is has been consultant for Radiation Management Consultants since 1990 and trains and drills approximately 5 hospitals/year until 1998. Developed the plan for radiation accidents at Loyola

* Dr Henkin is a member of the Radiation Information Network of the American College of Nuclear Physicians
* Drs Wagner and Henkin are Board Certified by ABNM

Radiation and Terrorism
* Public perceptions of radiation
* The good news and the bad news
* Terrorism scenarios
* Types of radiation injuries
* Hospital response to radiation incidents

The Public Perceptions
The Bad News
* Almost nothing creates more terror than radiation
o It’s invisible to touch, taste, and smell
o Most people have unrealistic ideas about radiation
o Most physicians don’t even understand it
* The objective of the terrorist is as much or more panic than it is physical harm

The Good News

* Nuclear Medicine and Radiation Therapy professionals are well trained in the fundamentals of radiation
* Respect radiation, but do not fear it
* Understand what radiation can and cannot do
* There have been industrial radiation accidents that we have learned much from
* It is easily detected in contrast to biological and chemical agents

What Can We Expect?
* Radiological/Nuclear Terrorism
o A true nuclear detonation
o A failed nuclear detonation
o Radiation dispersal device
* Power Plant attacks

A Nuclear Detonation
* Least likely scenario (fortunately)
* Most likely from a stolen nuclear weapon
* Results would be devastating, both psychologically and in terms of damage

The Unthinkable
* Effects of a 1 megaton detonation in Chicago
o 30% of all hospitals destroyed in 50 mile radius
o Transportation and infrastructure compromised
o Emergency vehicles and professionals unable to respond
o Walking wounded with burns may have been fatally irradiated – unknown effects for days to weeks

Radiological Devices
* Not a “nuclear explosion”
* Consists of a bomb designed to disperse radioactive materials in air and water
o Designed to create panic
o Difficult to clean up, material spreads
o Biological effects may take years to appear
* “A Dirty War” HBO/BBC Films 2005

Failed Nuclear Detonation
* Most likely from an improvised nuclear device (IND)
* Beyond the scope of an individual terrorist – would need 10-15 people
* Greatest barrier is availability of weapons grade material
* Would create a critical mass or explosion, but not the same degree as a true nuclear detonation.
* Nuclear material needs to stay in contact for a longer period of time to allow flux to form

Radiological Dispersal Device

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30 December 2009

Clinical Trials



Medical Epidemiology Clinical Trials

A clinical trial is
* A cohort study
* A prospective study
* An interventional study
* An experiment
* A controlled study

The Structure of a Clinical Trial
Various Aspects Are Standardized and Protocol-based
* Subject selection (who are these people?!)
* Subject assignment
* H & P data
* Therapeutic intervention
* Lab calibration
* Outcome evaluation

Subject Selection
* Adequate number of subjects
* Adequate number of expected endpoints
* Easy to follow-up
* Willing to participate (give consent)
* Eligibility (criteria)
* Efficacy Versus Effectiveness
* Internal Validity (validity) versus External Validity (generalizability)

Phases
* Phase I: find toxic dose
* Phase II: no controls
* Phase III: RCT
* Phase IV: Post marketing?

Types of Control Groups
* Historical
* Contemporaneous
* Concurrent
* Randomized

Allocating Treatment
* Complete (Simple) randomization
* Restricted randomization

Complete Randomization
* Patients assigned by Identical chance process (but not necessarily in equal numbers)
* Mechanics
* Insures process fairness
* Does not insure balance, especially in small studies.Therefore, may still need statistical adjustment

Randomization
* The only way to deal with unknown confounders.

Philosophy of Randomization
* Why are randomized trials not “epidemiologic” studies?
* Why randomization is so special?
* Has nothing to do with sampling bias.
* Randomization (random allocation) versus random sample.
* Does NOT deal with “chance” as a possible explanation of the difference. To the contrary.
* Can be used to create groups of unequal size.
* Baseline characteristics (table 1).

Allocation Concealment
* Define.
* Why do we need it?
* How is it done?
* Buzz words
* Versus blinding

Buzz Words
* Central (phone) randomization
* Sequentially numbered, opaque, sealed envelopes
* Sealed envelopes from a closed bag
* Numbered or coded bottles or containers

Restricted Randomization
* Stratification
* Blocking (Permuted Block Design)
* Stratified Blocking

Stratified Randomization
* Why

Scheme of stratified randomization
Blocking
* Why?
* Ensures close balance of the numbers in each group at all times during trial.
* How is it done?
* More importantly when stratified.
* Problem If block size is discovered.
* Remedy: more blinding, varying block size, larger blocks.
* Basic, Randomized (random-sized), Stratified

Problems With Concurrent Controls

Use your imagination
Examples
Problems With Contemporaneous Controls
* Regional population differences.
* Regional practice differences.
* Diagnostic variations.
* Referral pattern biases.
* Variations in data collections.

Problems With Historical Controls
* A lot more

Why Do Controls in a Randomized Trial Do So Well ?!
* Volunteerism
* Eligibility
* Placebo effect
* Hawthorne effect
* Regression towards the mean

Placebo Effect
* Placebo can do just about anything (prolong life, cure cancer).
* Improve athletic performance
* Lower T4 count
* Placebo can do just about anything (prolong life, cure cancer).
* Placebo can also cause side effects (nocebo, Wile E Coyote effect).
* Placebo effect is very useful in medicine but in epidemiology it causes problems, so we try to equalize it between the 2 groups.
* We use placebo for other benefits.

Hawthorne Effect
* Hawthorne works of the Western Electric Co. Chicago, IL

Regression Towards the Mean
Course Evaluation Question
Explains difficult material:
* Strongly agree
* Agree
* Neutral
* Disagree
* Strongly disagree
* What difficult material ?

Regression Towards the Mean
Explains difficult material
ATTENTION
CAUTION
DIFFICULT MATERIAL AHEAD!

Regression Towards the Mean

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