Glomerular number and size in autopsy kidneys: the relationship to birth weight

BACKGROUND: In the Southeast United States, African Americans have an estimated incidence of hypertension and end-stage renal disease (ESRD) that is five times greater than Caucasians. Higher rates of low birth weight (LBW) among African Americans is suggested to predispose African Americans to the higher risk, possibly by reducing the number of glomeruli that develop in the kidney. This study investigates the relationships between age, race, gender, total glomerular number (Nglom), mean glomerular volume (Vglom), body surface area (BSA), and birth weight. METHODS: Stereologic estimates of Nglom and Vglom were obtained using the physical disector/fractionator combination for autopsy kidneys from 37 African Americans and 19 Caucasians. RESULTS: Nglom was normally distributed and ranged from 227,327 to 1,825,380, an 8.0-fold difference. A direct linear relationship was observed between Nglom and birth weight (r = 0.423, P = 0.0012) with a regression coefficient that predicted an increase of 257,426 glomeruli per kilogram increase in birth weight (alpha = 0.050:0.908). Among adults there was a 4.9-fold range in Vglom, and in adults, Vglom was strongly and inversely correlated with Nglom (r =-0.640, P = 0.000002). Adult Vglom showed no significant correlation with BSA for males (r = -0.0150, P = 0.936), although it did for females (r = 0.606, P = 0.022). No racial differences in average Nglom or Vglom were observed. CONCLUSION: Birth weight is a strong determinant of Nglom and thereby of glomerular size in the postnatal kidney. The findings support the hypothesis that LBW by impairing nephron development is a risk factor for hypertension and ESRD in adulthood.     

Influence of diet on CO2 production and ventilation in constant-load exercise

The coupling between ventilation (VE) and oxygen uptake (VO2) or carbon dioxide production (VCO2) was tested during constant-load cycle ergometry in five healthy, young female volunteers. The ratio of VCO2/VO2 (respiratory quotient, RQ) was altered during exercise by prior dietary manipulation involving three diets: (a) low carbohydrate (L), (b) high carbohydrate (H) and (c) normal, mixed (M) diet. The constant power output selected for a 10-min exercise period approximated 80% of the power output at the anaerobic threshold. At rest and during exercise, the RQ and blood lactate concentration were lower following the L diet than either the H or M diets. All measurements for the H and M diets were similar. In exercise, the VO2 was higher in the L diet (1428 ml/min) than the H diet (1293 ml/min) (P less than 0.05). Although the VCO2 tended to be lower and the VE higher during exercise in the L diet, these values were not significantly different from the H dit. The ratio of VE/VO2 was not different fro the two diets. In the L diet, VE/VCO2 was greater than the H diet (P less than 0.05). A kinetic analysis showed no differences as a consequence of the diets in the rate of adaptation of VO2, VCO2 or VE to the plateau levels. This study has demonstrated an uncoupling of the constant relationship between VE and VCO2 by prior dietary manipulation; however, the relationship between VE and VO2 remained constant in spite of a change in the metabolic RQ which altered VO2 and VCO2 at a constant power output.     

Delayed kinetics of VO2 in the transition from prior exercise. Evidence for O2 transport limitation of VO2 kinetics: a review

The influence of prior exercise state on the kinetics of VO2, VE, and HR was studied in six subjects. The exercise conditions tested were square wave increases in work rate from rest to 80% of the work rate at anaerobic threshold (AT), from O W loadless pedaling to 80% AT, from rest to 40% AT, and from 40% to 80% AT. The kinetic response was evaluated by the time constant (tau) and mean response time (MRT = time to achieve 63% response) as determined by nonlinear regression. For both VO2 and HR, tau and MRT were not significantly different in the rest or O W to 80% AT tests, but were significantly faster in the rest to 40% AT test and significantly slower in the 40% to 80% AT test than the rest and O W to 80% AT tests. The tau for VE was significantly slower in the 40% to 80% AT tests than in the other tests. The coincident variation of HR and VO2 kinetics is taken as support for the hypothesis that VO2 kinetics are controlled by oxygen transport. Evidence from the literature that supports both the oxygen transport and the oxygen utilization for the control of VO2 kinetics is reviewed.     

Reduced psychological morbidity after breast conservation

Psychological morbidity was compared in 52 patients treated by mastectomy and 67 patients treated by lumpectomy for early breast cancer. An informal counselling service was provided for all patients. Morbidity was measured at 6, 9 and 12 months after surgery with two self-rating scales: the general health questionnaire and the Leeds depression and anxiety scales. There was a significant excess of severe depression in the mastectomy group. In contrast to the findings of previous research, this result suggests that breast conservation reduces psychological morbidity.     

Effect of prolonged head-down bed rest on complex cardiovascular dynamics

We postulated that a change in complex dynamics of the cardiovascular system could be involved in the orthostatic intolerance observed after simulated weightlessness. Supine recordings of 1024 consecutive pulse intervals and systolic blood pressures were obtained on 7 subjects adapted to a 42 day head-down bed rest (day 22 and 42) but also before and 6 days after head-down bed rest (-6 degrees). Coarse graining spectral analysis was used to extract the non-harmonic (fractal) component from each time series. The power spectral densities of this fractal component are inversely proportional to their frequency (1/f beta). We fitted an inverse power law estimate to the fractal component to determine the spectral exponent beta. The complex dynamics of blood pressure and heart rate variability were also analyzed by correlation dimension and non-linear prediction. Bed rest induced orthostatic intolerance in 4 subjects. There was a significant increase in the spectral exponent beta of RR-interval variability during and after head-down bed rest (before: 1.039 +/- 0.090; during: 1.552 +/- 0.080 and 1.547 +/- 0.100; after: 1.428 +/- 0.040). Analysis of the blood pressure dynamics indicated lower correlation dimensions during head-down bed rest and higher coefficients of predictability after head-down bed rest. Complexity alterations of RR-interval and blood pressure variability were not linked with one another during head-down bed rest. These alterations seemed to be correlated with the orthostatic intolerance observed after bed rest. These results suggest a change of the integration level of cardiovascular autonomic regulation.     

Use of hyperspectral imaging to distinguish normal, precancerous, and cancerous cells

BACKGROUND: The objective of the current study was to test the hypothesis that the cytologic diagnosis of cancer cells can be enhanced by the technique of hyperspectral imaging (HSI). METHODS: As a proof of principle, HSI was employed to obtain hyperspectrum from a normal human fibroblast, as well as its telomerase-immortalized and SV40-transformed derivatives. Novel algorithms were developed to differentiate among these cell models based on spectral and spatial differences. Using the same technique with modified algorithms, the authors were able to differentiate among normal and precancerous (low-grade [LG] and high-grade [HG]) cervical cells and squamous cell carcinoma (SCC) on liquid-based Papanicolaou (Pap) test slides. RESULTS: The specificity for identifying normal fibroblast cell type based on spatial and spectral algorithms was 74.2%. The sensitivity for identifying telomerase-immortalized and SV40-transformed cells was 100% and 90.3%, respectively. The system identified normal cervical cells with a specificity of 95.8%. With regard to LG precancerous cells and HG precancerous cells, the sensitivity was 66.7% and 93.5%, respectively. The sensitivity detected for SCC was 98.6%. CONCLUSIONS: HSI can be utilized in prescreening liquid-based Pap test slides to improve efficiency in Pap test diagnoses with the goal of ultimately reducing the mortality from cervical cancer while reducing health care costs.     

Reduced oxygen uptake during steady state exercise after 21-day mountain climbing expedition to 6,194 m.

We investigated the effect of a 21-day climbing expedition to 6,194 m on the oxygen uptake (V022) and leg blood flow (LBF) responses to submaximal exercise in five healthy, fit men during two-leg kicking exercise a 0-W and 50-W. Tests were completed 1 week before and 3 days after altitued acclimatization. The adaptation of VO2 at exercise onset was described by the time to 63% of the new steady state. Steady state VO2 during 50-W exercise was less post-climb (1290+/- 29 mL/min, mean +/- SE) than pre-climb (1413+/- 63 mL/min, P <.05). VO2 adapted more slowly at the onset of 50-W exercise post climb. There were no differences in the steady state LBF during the 50-W exercise, the increase above baseline, or the adaptation post-climb. Respiratory exchange ratio was greater at 50-W post-climb compared to pre-climb. Reduced steady state V02 during exercise after exposure to high altitude is consistent with an increase in metabolic efficiency.     

Gas exchange analysis of immediate CO2 storage at onset of exercise

The immediate storage of CO2 at the onset of exercise was estimated in 5 subjects as the difference between measured and predicted CO2 production at work rates of 33, 53 and 75% VO2max. Three time varying models of respiratory exchange ratio (RER) were used to obtain an expected range of predicted CO2 production. Calculated CO2 storage in the transition from rest to 33% VO2max ranged from 0.33 to 0.38 ml X kg-1 X torr-1; from 33 to 53% VO2max, corresponding values were -0.04 to 0.14 ml X kg-1 X torr-1; and, from 53 to 75% VO2max, values ranged from -0.25 to 0.16 ml X kg-1 X torr-1. In two models, CO2 storage decreased significantly at the highest work rate. Estimates of CO2 storage by hyperventilation in the steady state of exercise yielded significantly greater storage. It was concluded that immediate CO2 storage at the onset of exercise was less than hyperventilation estimates, and that it tended to decrease with metabolic acidosis.