Exteroceptive suppression of temporalis and masseter muscle activity is enhanced in offspring of hypertensives

Exteroceptive suppression of temporalis and masseter muscle activity was examined in young men with and without a parental history of hypertension. Recent clinical studies suggest that the second exteroceptive suppression period is attenuated in several chronic pain disorders and that this brainstem reflex may serve as a noninvasive index of endogenous pain control. In the present study, offspring of hypertensives exhibited a significant protraction of the late exteroceptive suppression period for both muscle sites, suggesting that the decreased pain sensitivity previously observed in individuals at risk for hypertension may be related to enhanced central pain modulation.     

Relative Dispersions of Intra-albumin Transit Times across Rat and Elasmobranch Perfused Livers,and Implications for Intra- and Inter-species Scaling of Hepatic Clearance using Microsomal Data

It is recognized that vascular dispersion in the liver is a determinant of high first-pass extraction of solutes by that organ. Such dispersion is also required for translation of in-vitro microsomal activity into in-vivo predictions of hepatic extraction for any solute. We therefore investigated the relative dispersion of albumin transit times (CV²) in the livers of adult and weanling rats and in elasmobranch livers. The mean and normalized variance of the hepatic transit time distribution of albumin was estimated using parametric non-linear regression (with a correction for catheter influence) after an impulse (bolus) input of labelled albumin into a single-pass liver perfusion. The mean±s.e. of CV² for albumin determined in each of the liver groups were 0·85 ± 0·20 (n = 12), 1·48 ± 0·33 (n = 7) and 0·90 ± 0·18 (n = 4) for the livers of adult and weanling rats and elasmobranch livers, respectively. These CV² are comparable with that reported previously for the dog and suggest that the CV² of the liver is of a similar order of magnitude irrespective of the age and morphological development of the species. It might, therefore, be justified, in the absence of other information, to predict the hepatic clearances and availabilities of highly extracted solutes by scaling within and between species livers using hepatic elimination models such as the dispersion model with a CV² of approximately unity.     

Respiratory sinus arrhythmia: Autonomic origins, physiological mechanisms, and psychophysiological implications

Respiratory sinus arrhythmia (RSA) is being used increasingly in psychophysiological studies as an index of vagal control of the heart and may be among the most selective noninvasive indices of parasympathetic control of cardiac functions. A comprehensive understanding of RSA, however, requires an appreciation of its multiple autonomic and physiological origins. We review the physiological bases of RSA and show that RSA arises from multiple tonic and phasic processes of both central and peripheral origin. These underlying mechanisms are at least partially differentiated, have distinct dynamics and consequences, and may be differentially sensitive to behavioral and cognitive events. These multiple mechanisms are relevant for psychophysiological studies of RSA, and a thorough understanding of RSA can only be achieved through an appreciation of the dynamics of its underlying origins. There is a distinction between the psychophysiological and neurophysiological domains, and conceptual and empirical bridges between these domains are needed.     

新生儿B组链球菌感染的预防

B组链球菌也称为无乳链球菌,是导致新生儿患病和死亡的重要原因之一,可导致败血症、肺炎和脑膜炎。过去十年间,针对B组链球菌主要是预防早发感染,所谓早发感染是指发生于出生后1周内的新生儿感染。采取的预防措施是给感染B组链球菌的孕妇和新生儿选择性地服用抗生素,以减少或消除B组链球菌的垂直传播。目前,尚没有其他办法能完全预防新生儿B组链球菌败血症的发生,在分娩期内对母亲的预防或者结合分娩后对新生儿的预防,可分别使新生儿早发疾病的发病率减少80%和95%。1病因和危险因素已经证实,高达30%的女性阴道和直肠、肛门携带B组链球菌,…     

Autonomic cardiac control. I. Estimation and validation from pharmacological blockades

Pharmacological blockades have been used to estimate the relative contributions of the autonomic branches to cardiac chronotropic control. Systematic biases in these estimates, however, can arise from both methodological and physiological factors. Selective blockades can be interpreted by two inferential models, and a single blockade condition can yield estimates of autonomic control for both autonomic branches. The residual autonomic control of the heart after blockade of a single division provides an index of the functional contribution of the unblocked branch. In contrast, the change in chronotropic state of the heart after blockade of the same division reflects the subtractive loss of that branch and thus provides an index of the normal contribution of the blocked branch. We demonstrate that the systematic biases that can arise in blockade studies introduce distortions of the subtractive and residual estimates that are of equal magnitude but opposite sign. Consequently, the discrepancy between the subtractive and residual-model estimates provides a measure of bias in blockade studies and permits the derivation of validity indices that can facilitate interpretations of blockade data.     

Haemangiopericytoma - Queensland Radium Institute Experience and a Review of the Literature

We report the presenting clinical characteristics, management, relapse patterns and survival of 17 patients with haemangiopericytoma treated at the Queensland Radium Institute, Australia from 1962 to 1989. Twelve patients were referred at the time of first diagnosis and were treated with curative intent. Three patients were treated with palliative intent when referred following initial diagnosis, and the remaining two patients were referred at the time of relapse. Disease was metastatic at presentation in 4 patients. Radiotherapy was used as a component of primary treatment of disease in 11 patients, in both patients referred for management of local relapse of haemangiopericytoma, and for palliation of metastatic disease developing in 3 patients. One patient received chemotherapy as part of initial treatment. Nine patients have died with survival from first treatment ranging from 3 to 139 months. Ail 8 surviving patients remain free of disease at 6 to 94 months from first treatment.