Faculty Bibliography

A probabilistic model of aging is considered. It is based on the assumption that a random resource, a stochastic process of aging (wear) and the corresponding anti-aging process are embedded at birth. A death occurs when the accumulated wear exceeds the initial random resource. It is assumed that the anti-aging process decreases wear in each increment. The impact of environment (lifestyle) is also taken into account. The corresponding relations for the observed and the conditional hazard rate (force of mortality) are obtained. Similar to some demographic models, the deceleration of mortality phenomenon is explained via the concept of frailty. Simple examples are considered

Evidence of sexual dimorphism before fetal gonadal differentiation in mammals has been accumulating, suggesting that male embryos develop faster than female ones. The current investigation was performed to evaluate whether the development rate of precompacted human embryos is controlled by sex chromosomes. Sex was determined by polymerase chain reaction and fluorescence in situ hybridisation in 172 arrested embryos derived from in vitro fertilisation. The sex ratio (1.02:0.98) did not differ significantly from 1:1. Although more males appeared to have greater fragmentation, the difference between the sex ratios of highly fragmented and normal embryos (1.08:0.92) was not significant. Arrested female embryos had a tendency to exhibit more than five nuclei and less than 10% fragmentation, but the trend was not statistically significant. The current results suggest that the first developmental block in human embryos occurs prior to and shortly after genomic activation and is not determined by the presence of the Y chromosome

Estimates of glomerular filtration rate are generally obtained by measuring or estimating endogenous creatinine clearance. However, it may sometimes be difficult to obtain the necessary urine collections. Most of 19 healthy, reliable elderly outpatients were found unable to provide satisfactory 24-hour urine collections. To judge whether formulas estimating creatinine clearance from serum creatinine levels are reliable, we also compared 24-hour creatinine clearances measured in 50 inpatients with values calculated by the Cockroft-Gault equation. Only a moderate correlation was found, which may be unacceptable in the clinical situations for which the equation is used, such as drug dosing. For reasons including uncertainties in the validity of predictive formulas and unreliability of urine collections, we conclude that no acceptable method now exists for bedside estimation of glomerular filtration rate and that drug levels should be measured whenever possible in elderly patients and in those with renal insufficiency

With aging, many aspects of immune function change. Despite the greater complexity of problems and increased numbers of variables that attend research involving aged individuals, certain fundamental alterations in immune reactivity appear associated with aging. These alterations have important biologic implications. The immune changes in 'healthy' octogenarians can have significant clinical effects when these individuals suffer stress or disease

In two separate studies, specimens of saliva from 57 individuals over the age of 65 years (mean age, 76.7 years) and 37 persons under the age of 40 years (mean age, 28.8 years) were examined for concentrations of IgA as functions of volume, total protein, and electrolyte conductivity; some were also tested for IgG and IgM content. The results show that older persons have higher concentrations of these solutes in their saliva than do younger controls. This suggests that the ability to secrete IgA into saliva does not diminish significantly with aging

In order to evaluate the effect of age on the presentation of and response to acute bacterial infection, the hospital charts of 187 adult patients with community-acquired pneumococcal bacteremia admitted to Bellevue Hospital over a nine-and-a-half year period were reviewed. Compared with younger patients, older patients (aged 65 or older) more frequently had (1) a lower fever in response to the infection, (2) an unclear history of illness, (3) a delay in diagnosis and/or therapy, and (4) a higher risk of dying. On admission, their leukocyte counts and heart rates were similar to those in a group of younger patients, which was composed largely of alcoholic patients and those addicted to intravenous drugs. Response to therapy was also similar in surviving older patients. Lower temperature and an unclear history were features most commonly associated with both delayed diagnosis and higher mortality. When patients with a history of alcohol abuse and those dying shortly after admission (i.e., presenting in a moribund state) were eliminated from the analysis, many of these age-related differences in presentation and outcome became even more evident