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Biomedical subjects

G H Hall

Publications and source records attributed to G H Hall.

17 recordsLinked to original sources
PubMed1992

Blood-brain exchange routes and distribution of 65Zn in rat brain.

Zinc is essential for normal development and function of the CNS although much is to be learned about brain Zn homeostasis. In these experiments adult male Wistar rats within the weight range 500-600 g were used. Ventriculo-cisternal perfusion was performed to allow the measurement of 65Zn fluxes between blood and csf across the choroid plexuses. Blood-brain or blood-cerebrospinal fluid barrier permeability to 65Zn has been determined by graphical analysis in experiments that lasted between 5 and 180 minutes. Cerebral capillary permeability to 65Zn was found to be low with a K(in) of about 5 x 10(-4)ml/min/g. Choroid plexus permeability to 65Zn was about 12 fold greater, although Zn influx to brain via this route was less than 5% that across cerebral capillaries. The autoradiographic distribution of 65Zn in brain showed regional variation with lowest levels in white matter and high levels in the dentate gyrus and hippocampus.

Animals↗
PubMed1991

Coronary risk-disk.

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Coronary Disease↗
PubMed1991

65Zn uptake from blood into brain in the rat.

Zinc is essential for the normal development and function of the CNS, although little is known about brain zinc homeostasis. Therefore, in this investigation we have studied 65Zn uptake by brain from blood and have measured the blood-brain barrier permeability to 65Zn in the anaesthetised rat in vivo. Adult male Wistar rats within the weight range 500-600 g were used. 65ZnCl2 and 125I-albumin, the latter serving as a vascular marker, were injected intravenously in a bolus of normal saline. Sequential arterial blood samples were taken during experiments that lasted between 5 min and 5 h, after which the whole brain was removed, dissected, and analysed for radioisotope activity. Data have been analysed by graphical analysis, which suggests that after 30 min of circulation, 65Zn uptake by brain from blood is unidirectional with an influx rate constant, Kin, of approximately 5 X 10(-4) ml/min/g. At circulation times of less than 30 min, 65Zn fluxes between blood and brain are bidirectional, where influx has a K value of greater than 5 X 10(-4) ml/min/g. In addition to the blood space, the brain appears to contain a rapidly exchanging compartment(s) for 65Zn of approximately 4 ml/100 g, which is not CSF.

Animals↗
PubMed1990

65zinc uptake from blood into brain and other tissues in the rat.

Zinc is essential for normal growth, development and brain function although little is known about brain zinc homeostasis. Therefore, in this investigation we have studied 65Zn uptake from blood into brain and other tissues and have measured the blood-brain barrier permeability to 65Zn in the anaesthetized rat in vivo. Adult male Wistar rats within the weight range 500-600 g were used. 65ZnCl2 and [125I]albumin, the latter serving as a vascular marker, were injected in a bolus of normal saline I.V. Sequential arterial blood samples were taken during experiments that lasted between 5 min and 5 hr. At termination, samples from the liver, spleen, pancreas, lung, heart, muscle, kidney, bone, testis, ileum, blood cells, csf, and whole brain were taken and analysed for radio-isotope activity. Data have been analysed by Graphical Analysis which suggests 65Zn uptake from blood by all tissues sampled was unidirectional during this experimental period except brain, where at circulation times less than 30 min, 65Zn fluxes were bidirectional. In addition to the blood space, the brain appears to contain a rapidly exchanging compartment(s) for 65Zn of about 4 ml/100g which is not csf.

Animals↗
PubMed1990

A comparison of methods for nasal mast cell demonstration.

Nasal turbinates were studied from 14 rhinitis patients following surgical turbinectomy, and from five subjects at autopsy. Mast cell counts on turbinectomy specimens were compared following staining with toluidine blue or Alcian blue and safranin after fixation in either paraformaldehyde or neutral buffered formalin. Mast cell numbers were significantly greater in the superficial submucosa than in the epithelium or deep submucosa in both the rhinitis group and the autopsy subjects. The combination of PFA fixation and ABS staining gave maximum mast cell counts, revealed two morphological mast cell sub-types and gave optimal demonstration of nasal tissue. Nasal mast cells are thus not uniformly distributed, appear heterogeneous under light microscopy, are present in large numbers even in the elderly, and are best demonstrated using PFA fixation and ABS staining.

Adolescent↗
PubMed1978

Intra-articular methotrexate. Clinical and laboratory study in rheumatoid and psoriatic arthritis.

The effects of intra-articular methotrexate (MTX) were compared with saline in 20 patients with persistent knee effusions due to rheumatoid arthritis (15) and psoriasis (5) in a double-blind pilot study. Clinical improvement was seen in most patients given either MTX or saline and was attributed to joint irrigation during arthroscopy and the placebo effects. MTX had a local anti-inflammatory effect in the psoriatic arthropathies; the percentages of polymorphonuclear cells and pyroninophilic mononuclear cells in synovial fluids fell sharply. Intraarticular hydrocortisone acetate was not anti-inflammatory in 2 psoriatic patients treated subsequently. The anti-inflammatory action of MTX in joints may resemble its effectiveness in controlling the rash of psoriasis.

Adult↗
PubMed1976

Copper toxicity: evidence for the conversion of cupric to cuprous copper in vivo under anaerobic conditions.

We have determined the toxicity to cells of Escherichia coli B of cupric copper applied under aerobic and anaerobic conditions in two ways. The growth of cells in liquid medium incorporating cupric copper shows differential inhibition, comparing aerobic and anaerobic conditions--toxicity being greater under anoxia. The growth of colonies upon agar plates incorporating cupric copper does not show such a differential effect. We conclude that colonies on plates are largely anoxic even when incubated aerobically. EPR spectra of cells obtained at various times after application of cupric copper under anoxic conditions indicate the conversion of a considerable proportion of the Cu(II) to a non-paramagnetic species, probably Cu(I). We demonstrate that Cu(I) is more toxic than Cu(II) to cells when applied under anoxic conditions and conclude that the difference in toxicity of Cu(II) applied to cells under aerobic and anaerobic conditions results from the greater extent of reduction of Cu(II) to Cu(I) under anaerobic conditions.

Aerobiosis↗
PubMed1975

Letter: SI units.

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Medical Records↗