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T Barnard

Publications and source records attributed to T Barnard.

34 records · Page 2Linked to original sources
PubMed1976

Ultrastructrual effects of chemical sympathectomy on brown adipose tissue.

Adult rats maintained at 20-22 degrees C, were exposed to 4 degrees C for 30-60 min and injected with 50 or 100 mg/kg 6-hydroxydopamine (6-OHDA) in an attempt to achieve a similar degree of chemical sympathectomy of nerves terminating among the adipocytes and the smooth muscle cells of the blood vessels in the interscapular brown adipose tissue (BAT). After 1, 4 or 10 days the pads of BAT were removed and small sections from each pad prepared for electron microscopy; the remaining tissue was used for noradrenaline (NA) analysis for fluorescence histochemistry. Ultrastructural observations showed that 24 h after the 6-OHDA injection virtually all noradrenergic nerve terminals were distorted and contained aggregates of degenerated cell organelles. The destruction could be correlated with a disappearance of fluorescent varicosities and a reduction of measurable NA to 8-12% of the control value. There was no differential toxic effect of 6-OHDA on the terminals among the adipocytes compared to those associated with blood vessels. Thus, treatment with 6-OHDA is more effective than previous attempts using immunological or surgical methods to produce sympathectomy, because both of the latter methods only eliminate the innervation of the blood vessels and spare the nerve terminals of the adipocytes. 4 days after 6-OHDA injection there was no improvement in the morphology of the terminals but after 10 days there was an increase in the number of terminals and axons with a normal appearance and this was paralleled by an increase in extractable NA to 50% of the control value. Because of the relatively rapid recovery of NA content and reappearance of terminals of normal appearance within 10 days after 6-OHDA injection, these animals should be injected weekly when a more permanent sympathectomy of adipocytes and blood vessels is desired.

Adipose Tissue, Brown↗
PubMed1976

Chemical sympathectomy of interscapular brown adipose tissue.

Adult non-cold adapted rats were injected with 6-hydroxydopamine (6-OHDA) or saline and their interscapular brown adipose tissue (BAT) was removed after appropriate periods of time. Fluorescence histochemistry of control BAT demonstrated the presence of an extensive network of varicose fibers among the adipocytes and at the blood vessels. This was confirmed by electron microscopy which also revealed large and small dense core vesicles sparsely distributed in axons and terminals indicating the presence of noradrenaline (NA). After 6-OHDA injection the fluorescence from varicosities was abolished both among the adipocytes and at the vessels. Thus, chemical sympathectomy was more effective than surgical- or immunosympathectomy, which spare the innervation of adipocytes. Parallelling the disappearance of fluorescence was a significant decrease of measurable NA. During recovery the extractable NA increased before the reappearance of fluorescent varicosities. This could be explained by transmitter accumulation in the nervetrunks within the tissue, which, in general, appeared unaffected by 6-OHDA. A large number of cells with a strong yellowish fluorescence distributed through the BAT was unaffected by 6-OHDA. There was no evidence for the presence of intrinsic ganglia.

Adipose Tissue, Brown↗
PubMed1976

Clinical cholera caused by enterotoxigenic Escherichia coli.

A woman returning from Mexico was hospitalized as an emergency patient with hypovolemic shock due to dirrheal disease of less than 1-day duration. Her clinical course was similar to that of severe cholera--she excreted greater than 60 liters of stool and urine in a 4-day period. The etiological agent was a non-enteropathogenic serotype but enterotoxigenic strain of Escherichia coli (063:NM). The patient responded both agglutinating and antitoxic antibodies against this strain and its enterotoxin. An "enteropathogenic serotype," 0111:B4, was also isolated but this finding had no etiological significance.

Adult↗
PubMedDate not supplied

Perspectives on electrical equipment used in oxygen-enriched atmospheres.

The medical community has not seriously examined the safety of using medical devices in oxygen-enriched atmospheres (OEA) or with nitrous oxide. A review of applicable codes and standards, reports of actual incidents, and experiments on minimum ignition energy and on determining the extent of OEA around a patient receiving respiratory therapy suggests that guidelines are needed. Several means of ensuring the safety of electrical equipment to be used in conjunction with oxygen are recommended. These include: compliance with standards for flammable atmospheres; sealing to prevent OEA from reaching electrical components; ventilating to limit oxygen concentration; and limiting potential spark energy and surface temperatures. These recommendations are made in the hope that the medical community will address this issue further.

Electricity↗