Relationship of changes in maximal and submaximal aerobic fitness to changes in cardiovascular disease and non-insulin-dependent diabetes mellitus risk factors with endurance training: the HERITAGE Family Study.

The purpose of this study was to determine the relationship between changes in maximal oxygen uptake (VO2 max) and submaximal markers of aerobic fitness and changes in risk factors for cardiovascular disease (CVD) and non-insulin-dependent diabetes mellitus (NIDDM) consequent to a 20-week endurance training program. The 502 participants in this study were healthy and previously sedentary men (n = 250) and women (n = 252) of varying age (17 to 65 years) and race (blacks n = 142; whites n = 360) who had completed the HERITAGE Family Study testing and training protocol. Following baseline measurements, participants trained on cycle ergometers 3 days/week for a total of 60 exercise sessions starting at the heart rate (HR) associated with 55% of VO2 max for 30 minutes/session. This was progressively increased to the HR associated with 75% of VO2 max for 50 minutes/session, which was maintained during the last 6 weeks. VO2 max, heart rate at 50 W, power output at 60% of VO2 max, lipids and lipoproteins, resting blood pressure, body composition including abdominal fat (computed tomography [CT] scan), and blood glucose and insulin at rest and at peak following an intravenous glucose tolerance test (IVGTT) were determined both before and after training. Following training, there were significant increases in VO2 max (16%) and the power output at 60% of VO2 max and a significant decrease in HR at 50 W. These changes in markers of aerobic fitness were significantly correlated only to the changes in the body composition variables and the lipids and lipoproteins. Further, there was considerable individual variation in response for all variables studied. Finally, when risk factor data were analyzed by quartile of change in VO2 max, there were few significant relationships. It is concluded that there is a significant relationship between changes in markers of aerobic fitness and changes in several risk factors for CVD and NIDDM. However, the magnitude of these relationships is small.     

Comparison of PET with radioactive microspheres to assess pulmonary blood flow.

Microsphere technique is the reference for assessment of pulmonary blood flow (PBF) but is destructive; PET, however, can determine PBF noninvasively. Comparisons of these 2 methods are scanty. Our study aimed at comparing these 2 techniques using a mathematic model taking into account the right ventricle in determining the transit time of a tracer through lung tissue. METHODS: Ten normal pigs were investigated at baseline, during dobutamine infusion, and during 10 cm H(2)O of positive end-expiratory pressure. Under each condition, PBF was successively measured with PET (PET-PBF) and radioactive microspheres (MS-PBF). For PET-PBF, 2 mCi (74 MBq) (15)O-labeled water were injected intravenously over 20 s and PET scanning was performed for 10 min. The input function was determined noninvasively from PET and invasively from mixed venous blood withdrawals. PET-PBF was computed using a mathematic model taking into account the right ventricle in determining the transit time of the tracer through lung tissue. For MS-PBF, 1 given isotope was injected under a given condition. PET-PBF and MS-PBF for 5 lung regions were compared. RESULTS: PET-PBF significantly correlated with MS-PBF both over all experimental points (PET-PBF = 0.79. MS-PBF + 1,538; r = 0.79; P < 0.001) and in separate lung regions. Invasive and noninvasive input functions also correlated significantly (r = 0.90; P < 0.001). Simulations stressed the crucial role of the right ventricle to the transit time of tracer through lung tissue in the determination of PET-PBF. CONCLUSION: PBF can accurately be assessed using PET and a mathematic model taking into account the right ventricle in determining the transit time of a tracer through lung tissue. Noninvasive determination of the input function of the right ventricle is accurate and can readily be used for clinical applications.     

Chemical synthesis and properties of tetrabutylphosphonium-ion-doped polyacetylene

A direct method of introducing tetraalkylphosphonium ions into polyacetylene (PA) is described. The maximum doping levels achieved with reducing agents having various redox potentials were determined. The electrical and magnetic properties of resulting doped products were assessed. The thermal stability of this product was monitored by electrical conductivity measurements. An indirect ion-exchange technique was devised to insert the phosphonium ion into PA. A similar method was found useful for the preparation of reduced β-carotene, a soluble analogue of PA, containing tetraalkylphosphonium counterions. The stability of the resulting compound was also studied.     

Noteworthy occurrences

Psychiatric Quarterly -     

Preferential blood flow to brainstem during generalized seizures in the newborn marmoset monkey

The effect of generalized seizures on local cerebral blood flow was studied autoradiographically in 21 immature marmoset monkeys, using either [¹²³I]- or [¹³¹I]isopropyliodoamphetamine. Generalized convulsions were induced in ketamine-anesthetized and awake monkeys with bicuculline and continued for 4–59 min. During convulsions in marmosets less than 3 weeks of age, there was a striking rearrangement of blood flow in favor of the brainstem pontomedullary region. The ratios of blood flow in pons-medulla to blood flow in cerebral cortex, putamen, ventroposterior thalamic nuclei, lateral geniculate nuclei, cerebellum and hemispheric white matter increased1/12 to 2 timescompared to controls. In seizure animals 4–8 weeks of age, the redistribution of blood flow to brainstem did not occur. Although metabolic acidosis developed after 30 min of bicuculline-induced seizures, mean arterial blood pressure, temperature, arterial pO₂ and pCO₂ did not differ significantly from controls, indicating that hypoxemia, hypercapnia and hypotension cannot explain the altered cerebral blood flow pattern. The redistribution phenomenon could be explained by more hronounced vasodilatation in brainstem than many other brain regions during generalized seizures in newborn monkeys. Lack of significant vasodilatation in forebrain structures such as cerebral cortex could contribute to neuronal damage by limiting substrate supply at a time of increased metabolic activity.     

Population differences in the pattern of familial aggregation for sex hormone‐binding globulin and its response to exercise training: The HERITAGE family study

Familial influences were investigated for baseline sex hormone‐binding globulin (SHBG) and its response (post‐training minus baseline) to a 20‐week endurance exercise training program. One hundred, eighty‐four participants from 85 Black families in the HERITAGE Family Study (HERITAGE) were analyzed using a familial correlation model. Baseline SHBG values and the training response were adjusted for the effects of age, baseline BMI, testosterone, estradiol, and fasting insulin levels (plus baseline SHBG values for the training response) within four sex‐by‐generation groups prior to genetic analysis. Baseline SHBG levels were influenced by appreciable familial effects (maximum heritability h² = 54%) with neither spouse resemblance nor sex and generation differences in the correlations. This estimate is only slightly, but not significantly, smaller than the heritability of 64% reported previously in 428 participants from 99 White families in HERITAGE. In contrast to the modest familial effects for the training response in White participants in HERITAGE (h² = 25%), there were no evidence of familial resemblance in Blacks in the current study. Furthermore, there was heterogeneity for both baseline SHBG and the training response between Blacks and Whites in the pattern of familial aggregation. In conclusion, baseline SHBG levels are influenced by significant familial effects in both Blacks and Whites, independent of the effects of age, sex, and baseline values of BMI, testosterone, estradiol, and fasting insulin levels. Whereas modest familial effects were detected for the training response in Whites, the lack of similar effects in Blacks may be due to the smaller sample size. Am. J. Hum. Biol. 13:832–837, 2001. © 2001 Wiley‐Liss, Inc.     

Antigens of melanocytes and melanoma

Melanoma is a valuable model to study phenotypic traits that are regulated during cell differentiation and malignant transformation. Melanoma cells display extensive phenotypic and antigenic heterogeneity. Studies of this attribute have provided insight into events that take place during normal melanocyte differentiation and give clues to traits that contribute to malignancy. It is possible that the phenotypic and genotypic heterogeneity present among melanoma cells within a single lesion includes a subset of cells with traits that favor tumor progression and metastasis. This review discusses the identification and characterization of antigens expressed by melanoma cells and their potential contribution to melanocyte differentiation and malignant transformation.