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Biomedical subjects

M A Bell

Publications and source records attributed to M A Bell.

At least 55 records · Page 3Linked to original sources
PubMed1985

Laminar variation in the microvascular architecture of normal human visual cortex (area 17).

Diameters and densities of arterioles and capillaries were measured in thick alkaline phosphatase-stained sections of human visual cortex from normal young adults. Values were compared between laminae. Capillary diameters ranked: IV greater than V-VI greater than II-III greater than I; capillary densities ranked: IV greater than II-III greater than V-VI greater than I. The striking capillary density of lamina IV overlaps the stria Gennarii and, like it, is limited to area 17. The data suggest correlations with similar laminar distributions of some neurotransmitters and of certain common neuropathological lesions.

Adolescent↗
PubMed1984

A morphometric study of intrafascicular vessels of mammalian sciatic nerve.

Intrafascicular vessel profiles were measured with a Quantimet image analyzer in 1-micron transverse sections of sciatic nerves of rats and compared with those of ("white") skeletal muscle. Blood vessels occupy the same percentage of the total tissue area in nerve and muscle tissues. The nerve, however, has much larger capillaries (about 1.7 X) spaced farther apart (about 2.5 X). Comparison of 3 1/2 month with 1-year-old rats showed that muscle capillaries increased in diameter (slightly, but significantly) at maturity, but those of the nerve decreased (also significantly). Vascular percentages of total tissue areas did not change. Nerve and muscle samples from monkey, rabbit, mouse, and cat show that the same striking pattern of large, widely spaced vessels distinguishes the nerve from other tissues. Minor interspecies variations exist. The nerve may contain as much blood as the muscle but its angioarchitecture suggests a lower exchange capacity.

Age Factors↗
PubMed1984

Staining for microvascular alkaline phosphatase in thick celloidin sections of nervous tissue: morphometric and pathological applications.

Alkaline phosphatase enzyme is active in the endothelium of capillaries (and often arterioles) in the central and peripheral nervous systems of many animals including man. A modified metallic stain for this enzyme applied to thick (50-500 micron) sections of brain or nerve produces a striking picture of the microvascular system. Preparations may be examined by light microscopy or microfocal radiography. Thick sections (particularly at 100 micron) are suitable for vascular morphometry at the light microscopic level. Celloidin embedding of the material permits storage of the specimen and ensures that cohesive sections can be cut serially, labeled, and handled with ease. Counterstaining permits normal and pathological features of the parenchyma to be demonstrated in relation to the vessels. Techniques of preparation and morphometry are described. Examples are drawn from current studies of the hippocampal and calcarine microvasculatures and their relation to senile plaques in normal aging and senile dementia of the Alzheimer type.

Alkaline Phosphatase↗
PubMed1984

A descriptive study of the blood vessels of the sciatic nerve in the rat, man and other mammals.

The gross blood supply and internal vascular organization of the sciatic nerve in the rat (and other mammals including man) have been studied by injection, dissection, and microradiographic methods, in thick sections stained for alkaline phosphatase and semithin sections, and by electron microscopy. In the rat, an anastomotic vascular connection from the arteria comitans to the medial femoral circumflex artery is illustrated. In all species studied, the microvascular network of the nerve has an unusually large calibre and wide spacing, particularly when compared with that of skeletal muscle. Arterioles and venules are present within fascicles; the arterioles are thin-walled, with only rudimentary internal elastic laminae. Endoneurial capillaries are large, continuous and nonfenestrated, with prominent (often multiple) basal laminae and an unusually complete pericyte investment. Endothelial junctions appear to vary in type; not all are tight. Pinocytosis is common. The extensively interconnected vascular network of the nerve fascicle may act as an adaptable in situ reservoir for blood in the precise maintenance of the endoneurial milieu.

Alkaline Phosphatase↗
PubMed1983

Pre-operative localisation of parathyroid tumours using neck vein catheterisation and radioimmunoassay for parathyroid hormone: the Glasgow experience.

Reliable pre-operative localisation of parathyroid tumours can be of value in surgery for primary hyperparathyroidism, and particularly so where re-exploration of the neck is required. Neck vein catheterisation and parathyroid hormone radioimmunoassay have been suggested as a sensitive means of tumour localisation, and we report our experience of the technique over the last five years. A total of 46 patients with primary hyperparathyroidism had 50 studies performed with positive localisation and a pre-operative prediction made on 38 occasions (76%). Forty-two operations were carried out and a parathyroid tumour confirmed in 39 cases for a localisation efficiency of 69 per cent. No negative neck exploration followed a positive localisation. Twelve studies were performed in patients with renal osteodystrophy and localisation to a single site was achieved on only three occasions. It is concluded that neck vein catheterisation and parathyroid hormone assay can correctly localise parathyroid tumours in most cases of primary hyperparathyroidism, but it is suggested that its use be restricted to selected cases such as those subjects with previous negative neck exploration or patients for whom prolonged or repeated surgery may be a particular hazard.

Adenoma↗
PubMed1981

Morphometric comparison of hippocampal microvasculature in ageing and demented people: diameters and densities.

The diameters and densities of capillaries and arterioles in the hippocampal cortex of normal subjects and patients with Alzheimer's dementia were measured in thick celloidin sections stained for alkaline phosphatase. Microvascular diameters in general are affected more by age than by the presence of dementia of the Alzheimer type. The diameter of both capillaries and arterioles increases significantly with age. The density of capillaries decreases whereas that of the arterioles increases significantly. The capillary changes suggest that a reduced exchange potential accompanies ageing. In brains of people with Alzheimer's disease the overall capillary diameters and densities do not differ from those of age-matched controls. Regional changes may, however, be important: those hippocampal zones showing the greatest severity of or increment in nerve cell lesions do correspond to those having the highest levels of or increase in capillary density and the greatest decrease in diameter, suggesting a direct association between neuronal susceptibility to Alzheimer changes and degree of regional blood supply. Capillary surface areas, volumes and area/capillary volume ratios support the possibility of this relationship. Neurofibrillary tangles and granulovacuolar degeneration do not correlate equally with the degree of capillary "irrigation"; tangles are more closely related to these morphological vascular parameters.

Adult↗
PubMed1975

Indomethacin--aspirin interaction: a clinical appraisal.

Plasma profiles of indomethacin after a 50-mg oral dose were constructed in six healthy volunteers before and after a week of aspirin treatment. Aspirin did not interfere with indomethacin plasma levels. To examine the clinical effect of concurrent indomethacin and aspirin treatment 20 patients with seropositive rheumatoid arthritis were given indomethacin 100 mg/day, aspirin soluble 4 g/day, and the two drugs taken together in random order. Analysis of the clinical indices of inflammation--articular index and mean pain score--and of the efficacy of each treatment showed no significant differences between the three treatment groups. With the proliferation in the number of anti-rheumatic drugs available, the case for giving two or more nonsteroidal anti-inflammatory drugs concurrently remains unproved.

Arthritis, Rheumatoid↗