Autonomic regulation of reflex bradycardia in rats declines with age.

Heart rate responses, elicited reflexly by elevating blood pressure with phenylephrine or lowering it with sodium nitroprusside, were compared in groups of rats aged 4 and 14 months. All tests were done while the rats were awake to avoid artefacts due to anesthesia. Parasympathetic and sympathetic contributions were assessed by repeating baroreflex tests after cholinergic blockade with atropine or beta-adrenergic blockade with propranolol.

Aging escalates baroreceptor reflex suppression by the posterior hypothalamus in rats.

To examine whether baroreceptor reflex regulation by the posterior hypothalamus becomes modified with age, we compared baroreceptor reflex sensitivity and hypothalamic responsiveness in 2- and 10-month-old rats anesthetized with urethane-chloralose. Hypothalamic regulation of baroreceptor reflex sensitivity was assessed by recording responses to intravenously infused phenylephrine and afferent aortic nerve stimulation after sham operation or electrolytic destruction of the posterior hypothalamus. Regardless of age, reflex bradycardia and sympathoinhibition elicited during pressor responses to phenylephrine, as well as all cardiovascular and sympathetic nerve responses to afferent aortic nerve stimulation, were stronger in rats with bilateral hypothalamic lesions than in age-matched, sham-operated controls.

Pleomorphic xanthoastrocytoma with desmoplastic reaction: angiomatous variant. Report of two cases.

Two cases of cerebral pleomorphic xanthoastrocytomas (PXA-s) with prominent vascularity and desmoplastic changes occurring in young subjects are presented. The tumors displayed the marked pleomorphism characteristic of PXA-s and had variable cellularity. The cytoplasm of many tumor cells contained an abundance of lipid droplets.

Diminished cardiovascular responsiveness to vagal stimulation in obese rats.

Obese rats maintained on a high-fat diet since weaning were studied to determine whether parasympathetic deficiencies contribute to the cardiovascular malfunction in obesity. Elevations in tail-cuff systolic pressures and plasma insulin indicated that obese rats had borderline hypertension and hyperinsulinemia. Reflex bradycardia produced by angiotensin or phenylephrine in conscious obese rats was less than that in age-matched controls.

Renovascular beta adrenergic hypersensitivity and hyperinsulinemia in rats with dietary-induced obesity.

To determine whether obesity alters responsiveness to vasoactive drugs, we compared the cardiovascular effects of angiotensin, phenylephrine and isoproterenol in unanesthetized age-matched control and obese Oscai rats. Obesity was induced by programming pups to overeat immediately after birth and then feeding them a high-fat diet thereafter. Elevations in tail-cuff systolic and mean pressures from 7 through 11 months of age and in plasma insulin at 8 months of age indicated that obese rats had developed borderline hypertension and hyperinsulinemia.

Pressor and sympathetic responses to dorsal raphe nucleus infusions of TRH in rats.

Pressor, tachycardic, and sympathoexcitatory responses to intracerebroventricularly (icv) infused thyrotropin-releasing hormone (TRH) were recorded in urethan-anesthetized rats to identify where centrally administered TRH acts in the brain. None of these responses was altered either by electrolytic lesions in the medial preoptic, posterior, or paraventricular hypothalamus or by chemical lesions produced by destroying catecholaminergic neurons with icv infused 6-hydroxydopamine. By contrast, when serotonergic neurons were similarly destroyed with 5,7-dihydroxytryptamine, TRH-induced tachycardia was inhibited.

Adrenal cortical adenoma in the spinal canal of an 8-year-old girl.

An ectopic adrenal cortical adenoma containing high levels of androstenedione but without clinically detectable virilizing effects was found in the spinal intradural space of an 8-year-old girl. The tumor, which was located at the L2 level, manifested itself clinically by a short history of bilateral leg pain. It was well encapsulated; therefore, total surgical removal was accomplished.

Enhanced sympathetic mediation of chronotropic baroreflexes in old Sprague-Dawley rats.

We compared reflex heart rate responses elicited during intravenous infusions of phenylephrine or sodium nitroprusside in conscious 4- and 24-month-old male Sprague-Dawley rats to determine whether baroreflex regulation changes with age. Underlying neural mechanisms were assessed by repeating baroreflex tests following cholinergic blockade with methylatropine or beta-adrenergic blockade with propranolol. Basal blood pressures always tended to be higher, while corresponding heart rates were lower, in old than in young rats.

Age-dependent baroreflex attenuation by centrally infused verapamil in rats.

Because oral administration of verapamil for 6 days reduces reflex tachycardia without affecting reflex bradycardia, we tested chronotropic baroreflexes in conscious rats aged 5 or 15 months before and after verapamil was infused intracerebroventricularly for 6 days to determine whether a central action contributes to the reflex attenuation. Baroreflex responses consisted of reflex bradycardia elicited during pressor responses to methoxamine and reflex tachycardia during depressor responses to sodium nitroprusside. As we have shown previously, all reflex heart rate responses were initially smaller in 15-month-old than in 5-month old rats.

Baroreceptor reflex impairment and mild hypertension in rats with dietary-induced obesity.

Cardiovascular dysfunction associated with obesity was assessed by comparing rats that had been maintained on a regular or high fat diet since weaning. Rats on the high fat diet not only gained weight faster than age-matched controls but also had higher systolic and mean pressures. Development of mild hypertension in obese rats was first detected by indirect tail-cuff measurement and confirmed later by recording intra-arterial pressures directly from indwelling femoral catheters.

Mediation of reflex tachycardia becomes exclusively beta-adrenergic in old Fischer 344 rats.

To study how baroreflex regulation changes with age we compared reflex heart rate responses elicited in awake Fischer 344 rats of different ages during intravenous infusions of phenylephrine or sodium nitroprusside. Underlying neural mechanisms were assessed by repeating baroreflex tests following cholinergic blockade with methylatropine or beta-adrenergic blockade with propranolol. Basal heart rates always tended to be lower in old than in young rats, but the differences became statistically significant only after beta-adrenergic or combined cholinergic and beta-adrenergic blockade.

Baroreceptor reflex enhancement by chronic intracerebroventricular infusion of enalapril in normotensive rats.

Involvement of the brain renin-angiotensin system in baroreceptor reflex regulation was assessed by recording reflex heart rate and sympathetic nerve responses in normotensive rats that had been infused intracerebroventricularly with the converting enzyme inhibitor enalapril for 15 days. Reflex bradycardia and sympathetic nerve inhibition during pressor responses to phenylephrine were larger in rats with intracerebroventricularly infused enalapril than in control rats similarly infused either intracerebroventricularly with saline or intravenously with enalapril. In contrast, opposite reflex responses to sodium nitroprusside-induced hypotension were mostly unaffected.

Enhanced sympathetic pressor responses to intracerebrovascularly infused saline in awake salt-loaded rats.

Osmotic minipumps were used to infuse hypertonic saline intracerebroventricularly into conscious rats fed high-salt diets to determine if combining high-salt intake with ICV saline infusion would elevate blood pressure more than either procedure alone. Mean aortic pressures became progressively elevated in all rats infused with saline and the magnitude of the elevation was significantly larger in those fed high-salt diets instead of the regular chow. Added pressor effects of high-salt feeding were unaffected by pharmacologic vasopressin or angiotensin blockade thereby indicating that humoral mediation by either peptide was not involved.

Penetration of neuronal perikarya by capillaries in chronic limbic encephalitis.

In a case of chronic limbic encephalitis in a 57-year-old man many neurons in the pyramidal cell layer of the hippocampus bilaterally were penetrated by ingrowing capillaries. All gradations from slight to moderate indentation of the cell membranes to complete incorporation of the capillaries in the neuronal perikarya were observed. The penetrating capillaries retained their basement membranes.

Effects of microdialysis on brain metabolism in normal and seizure states.

The effect of intracranial microdialysis on brain glucose metabolism in control and kainic acid-treated rats was assessed by semi-quantitative [14C]2-deoxyglucose autoradiography. A dialysis fiber loop was implanted into the piriform cortex or a horizontal Vita fiber into the hippocampus, and 24 h later, fibers were perfused with Krebs-Ringer bicarbonate solution before and after injection of kainic acid (16 mg/kg, i.p.

Intracellular magnesium affects I(K) in single frog atrial cells.

Voltage-clamp experiments on single frog (Rana pipiens) atrial cells using whole cell recording techniques revealed that the addition of MgCl2 to the 150 mM KCl patch pipette solution influenced the voltage- and time-dependent potassium current (IK). After rupture of the membrane patch under the tip of the pipette, IK increased with time when the pipette solution was magnesium free, but decreased slightly when the solution contained 1.5 mM MgCl2.

Selective pressor enhancement by monoamine oxidase inhibitors in conscious rats.

To compare the cardiovascular effects of chronic monoamine oxidase (MAO) A and B inhibition, rats were given s.c. injections of saline clorgyline or l-deprenyl daily for 3 weeks.

Nucleotide sequences of genes encoding heat-stable and heat-labile glyceraldehyde-3-phosphate dehydrogenases; amino acid sequence and protein thermostability.

The structural gene (gapST) encoding glyceraldehyde-3-phosphate dehydrogenase (GPDH; EC 1.2.1.

Sensitivity to both vecuronium and neostigmine in a sero-negative myasthenic patient.

We describe a sero-negative ocular myasthenic patient who showed exaggerated responses to both vecuronium and neostigmine. These hypersensitive responses were not anticipated because preoperative clinical and laboratory evaluations suggested a negligible impairment of somatic muscles by myasthenic processes. This case report re-emphasizes that, if neuromuscular blocking agents and their antagonists are administered to myasthenic patients, regardless of the degree of impairment, the dose should be titrated carefully with the aid of a neuromuscular transmission monitor.

Cerebellar astrocytomas in elderly patients with very long preoperative histories: report of three cases.

Three patients, ages 69, 67, and 74 years, respectively, underwent surgical removal of cystic cerebellar astrocytomas. All three had past histories pointing to the existence of a cerebellar lesion for many decades prior to surgery: Patient 1 had had nystagmus on lateral gaze on the side of the tumor since early childhood; Patient 2 had had sensorineural hearing loss on the side of her neoplasm for 38 years preceding the operation; and Patient 3 was diagnosed as having a brain tumor 51 years before the operation. (He has been blind because of pressure hydrocephalus for half a century, but otherwise managed to live a productive farming and family life until he sustained a head injury in a car accident, which forced him to undergo removal of his cerebellar tumor.

Prevention and management of surgical complications during repair of abdominal aortic aneurysms.

Abdominal aortic aneurysms can be repaired with a mortality rate of 3 per cent or less under optimal conditions. To achieve these results, every effort must be made to prevent disastrous surgical complications in this elderly population. This review covers some of the more common and serious complications associated with aneurysm repair: their causation, prevention, diagnosis, and treatment.

Abdominal aortic aneurysmorrhaphy combined with biliary or gastrointestinal surgery.

Abdominal aortic aneurysms occur in 2 to 5 per cent of the population over 60 years of age. Statistically, 7 per cent of patients with aneurysms will have associated cholelithiasis. The incidence of other concomitant intra-abdominal disease is much less.

Scaling facial impairment.

A major goal of the treatment of cleft lip and palate is to improve the esthetic acceptability of the face. It is assumed that an improved esthetic appearance is associated with significant psychosocial benefits, but there is almost no empiric support for this assumption. Researchers have been hindered in the study of this problem because scales to measure severity of facial impairment of clefts have not been available; however, standard scales of facial impairment have been developed for occlusal traits, orthognathic structure, and facial attractiveness.

Modification of cardiac action potential by photosensitizer-generated reactive oxygen.

Evidence implicating reactive oxygen species (ROS) in reperfusion-induced arrhythmias is accumulating rapidly [1,2]. However, surprisingly little is known about the effects of ROS on cardiac electrophysiology. Such knowledge would improve our understanding of reperfusion-induced arrhythmias.

Age-related central and baroreceptor impairment in female Sprague-Dawley rats.

To determine whether baroreflex sensitivity changes with age, we compared drug-induced reflex responses in 2- and 9-mo-old female Sprague-Dawley rats anesthetized with urethan-chloralose. Baroreflexes were stimulated by elevating or lowering blood pressure with intravenous infusions of phenylephrine or sodium nitroprusside. Reflex responses in heart rate and sympathetic nerve activity during phenylephrine infusions were weaker in 9- than in 2-mo-old rats, as were reflex tachycardia during sodium nitroprusside infusion and decreases in heart rate and sympathetic nerve activity elicited by electrical stimulation of the left aortic depressor nerve.