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D R Wekstein

Publications and source records attributed to D R Wekstein.

34 records · Page 2Linked to original sources
PubMed1982

Heart rate adaptation to exercise training in cardiac-denervated dogs.

To determine the effect of cardiac denervation on the development of a training-induced decrease in heart rate at rest and during submaximal exercise, six cardiac-denervated (CD) and six sham-operated (SO) dogs were exercise trained by means of a 6-wk treadmill running program. Gastrocnemius citrate synthase activity increased significantly to the same degree in CD and SO dogs indicating that both groups were equally trained. Resting heart rates (RHR) for SO dogs decreased significantly from 64 +/- 4.8 to 51 +/- 3.2 beats/min (mean +/- SE) from pre- to posttraining. CD dogs showed no changes in RHR (95 +/- 3.5 to 96 +/- 5.3 beats/min). Heart rate responses of SO dogs to a standardized, submaximal exercise test decreased significantly from pre- to posttraining. However, CD dogs displayed no decrease in heart rate responses to the standardized, submaximal exercise test. Additionally, at pre- and posttraining, as heart rates rose in response to exercise test intensity, they increased to a significantly greater degree in SO dogs compared with CD dogs. The results indicate that in dogs, cardiac denervation prevents the decreases in resting heart rate and heart rate during submaximal exercise normally associated with endurance exercise training.

Adaptation, Physiological↗
PubMedDate not supplied

Trace elements in Alzheimer's disease pituitary glands.

Levels of mercury (Hg), selenium (Se), iron (Fe), rubidium (Rb), and zinc (Zn) were measured in the pituitary gland to assess the possibility of a potential difference in the environmental Hg exposure of Alzheimer's disease (AD) patients and control subjects and levels of other elements of interest in AD. The pituitary gland has been established as a good predictor of environmental Hg exposure. Neutron activation analysis was utilized to determine levels of these elements in pituitary glands of 43 AD subjects and 15 control subjects. No significant differences were observed between the AD and control means for these five elements. The sole significant Pearson's correlation involving Hg was the established correlation with Se, indicative of the detoxification of Hg. The absence of a statistical difference between AD and control pituitary gland Hg levels suggests AD patients do not have an excessive environmental exposure to Hg compared to controls.

Aged↗
PubMedDate not supplied

Carboxy terminal of beta-amyloid deposits in aged human, canine, and polar bear brains.

Immunocytochemistry, using antibodies specific for different carboxy termini of beta-amyloid. A beta 40 and A beta 42(43), was used to compare beta-amyloid deposits in aged animal models to nondemented and demented Alzheimer's disease human cases. Aged beagle dogs exhibit diffuse plaques in the absence of neurofibrillary pathology and the aged polar bear brains contain diffuse plaques and PHF-1-positive neurofibrillary tangles. The brains of nondemented human subjects displayed abundant diffuse plaques, whereas the AD cases had both diffuse and mature (cored) neuritic plaques. Diffuse plaques were positively immunostained with an antibody against A beta 42(43) in all examined species, whereas A beta 40 immunopositive mature plaques were observed only in the human brain. Anti-A beta 40 strongly immunolabeled cerebrovascular beta-amyloid deposits in each of the species examined, although some deposits in the polar bear brain were preferentially labeled with anti-A beta 42(43). beta-amyloid deposition was evident in the outer molecular layer of the dentate gyrus in the aged dog, polar bear, and human. Within this layer, A beta 42 was present as diffuse deposits, although these deposits were morphologically distinct in each of the examined animal models. In dogs, A beta 42 was cloud-like in nature; the polar bear demonstrated a more aggregated type of deposition, and the nondemented human displayed well-defined deposits. Alzheimer's disease cases were most frequently marked by neuritic plaques in this region. Taken together, the data indicate that beta-amyloid deposition in aged mammals is similar to the earliest stages observed in human brain. In each species, A beta 42(43) is the initially deposited isoform in diffuse plaques.

Aged↗