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Biomedical subjects

A B Harris

Publications and source records attributed to A B Harris.

17 recordsLinked to original sources
PubMed1979

Inhibitory, GABAergic nerve terminals decrease at sites of focal epilepsy.

Using an immunocytochemical method for the localization of the gamma-aminobutyric acid (GABA) synthesizing enzyme, glutamic acid decarboxylase (GAD), we have observed GABAergic nerve terminals distributed throughout all layers of normal monkey sensorimotor cortex. These terminals displayed ultrastructural characteristics that suggested that they arose from aspinous and sparsely spinous stellate neurons. In monkeys (Macaca mulatta and M. fascicularis) made epileptic by cortical application of alumina gel, a highly significant numerical decrease of GAD-positive nerve terminals occurred at sites of seizure foci indicating a functional loss of GABAergic inhibitory synapses. A loss of such inhibition at seizure foci could lead to epileptic activity of cortical pyramidal neurons.

Animals↗
PubMed1979

Individual susceptibility to neisserial infection?

Specimens from genital, anorectal, and pharyngeal sites from 1671 men and 1419 women were cultured for Neisseria gonorrhoeae. Pharyngeal specimens were also cultured for Neisseria meningitidis, N. gonnorrhoeae was isolated from a genital site 2.7 times more often in men and 1.8 times more in women who also carried meningococci in their pharynx than from those who did not; the meningococcus was isolated 3.4 times more often from men and 2.0 times more often from women with genital gonorrhoea than from those without. In both men and women the association of each organism with the other was statistically significant (p less than 0.001) and may be related to sexual behaviour rather than to individual susceptibility to neisserial infection.

Cervix Uteri↗
PubMed1979

Screening by culture for the detection of gonorrhoea in women.

The number of gonoccal infections detected by each of three sets of diagnostic cultures from the urethra, cervix, rectum and occasionally the throat, were calculated for 1976 when Thayer Martin (TM) medium was used and for 1977 when Modified New York City (MNYC) medium was used. In 1977, 98.7 per cent (451/457) of the total infections diagnosed were confirmed by culture compared with 88.3 per cent (324/367) of infections diagnosed in 1976 (P less than 0.001). The first set of diagnostic tests detected 97.6 per cent (440/451) of culture-positive infections in 1977 compared with only 88.9 per cent (228/324) in 1976 (P less than 0.001). The efficiency of screening with a single endocervical culture was also calculated. This procedure would have detected 90.2 per cent (407/451) of culture-positive infections in 1977 when MNYC medium was used compared with only 78.1 per cent (253/324) in 1976 when TM medium was used (P less than 0.001). It is suggested that the statistically significant improvement in the culture results for 1977 resulted from the introduction of MNYC medium since all other diagnostic procedures were identical to those in 1976. Other advantages associated with the use of MNYC medium are discussed.

Bacteriological Techniques↗
PubMed1979

Pituitary tumor made symptomatic during hormone therapy and induced pregnancy.

An infertile patient with amenorrhea-galactorrhea syndrome lost vision during a pregnancy occurring after Bromocryptine treatment. A pituitary adenoma was removed, vision recovered, and the pregnancy completed successfully. Two prior episodes of visual loss had occurred during oral contraceptive treatment, an association not heretofore reported. Intrasellar and parasellar tumors made manifest by hormonal influences of pregnancy may become more common as treatment of infertility becomes more refined and successful.

Adenoma, Chromophobe↗
PubMed1978

Epileptogenic agents applied to trigeminal ganglia: absence of neuronal hyperexcitability.

Chronic application of alumina cream to the trigeminal ganglion in 10 cats failed to produce a long-lasting behavioral syndrome of facial dysesthesia. Histologic and electron microscopic analysis demonstrated morphologic similarities between these ganglia and primate neocortical alumina cream epileptic foci. None of 87 ganglia neurons recorded extracellularly exhibited evidence of intrinsic hyperexcitability, i.e., abnormal spontaneous or physiologically evoked activity or any significant differences in threshold of responses to antidromic or orthodromic electrical stimulation, compared to 67 normal ganglion cells. Furthermore, topical application of penicillin to normal ganglia failed to produce abnormal activity in 42 neurons tested. These data suggest that neuronal somata lacking either dendrites or postsynaptic membranes, or both, do not develop abnormal firing behavior when challenged with these two epileptogenic agents.

Aluminum Hydroxide↗
PubMed1978

Aphasia and left thalamic hemorrhage.

Left thalamic hemorrhage as a cause of aphasia has not been widely recognized. Large thalamic hemorrhages cause coma, making speech examination impossible; smaller thalamic hemorrhages were difficult to document until recent diagnostic advances. Nine cases of thalamic hemorrhage with aphasia have been described in the literature. This report presents four additional cases. These patients had acute onset of aphasia, supranuclear paralysis of upward gaze, right hemisensory deficits, and mild right hemiparesis. Three of the four patients responded to ventriculostomy drainage with rapid clearing of the supranuclear paralysis of upward gaze, and two later required placement of permanent ventricular shunts. After 1 year, two patients exhibited no clinically detectable speech malfunction and the other two were severely aphasic. The hemiparesis, hemisensory deficits, and ocular pareses all cleared. These cases are discussed with respect to present models of the role of the thalamus in speech.

Adult↗
PubMed1976

Kinetics of horseradish peroxidase migration through cerebral cortex.

This study provides a semiquantitative description of the migration of the extracellular space marker, horseradish peroxidase (HRP), through the cerebral cortex. Following a continuous subarachnoid infusion of HRP, this marker was fixed rapidly within the cortical extracellular space (ECS) by intravascular aldehyde perfusion fixation. Microscopic measurements of the maximum depth of penetration of HRP into the cortex perpendicular to the pial surface were taken from coronal whole brain sections of rabbits that had been exposed to HRP for varying periods of time. The depth of penetration plotted as a function of time of exposure to HRP produced a 'diffusion profile'. The failure of experimental points to conform to an ideal diffusion curve indicates that simple diffusion alone is an inadequate explanation of the rate of movement of large molecular solutes from the subarachnoid space through the cerebral cortical ECS. The complex pattern of migration velocity of HRP through cortex may be due to alterations of flux of this solute which result from variations in the volume of ECS in different cortical laminae and to the presence of bulk flow of extracellular fluid in the deeper cortical regions.

Animals↗
PubMed1976

Surgical anatomy of the proximal anterior cerebral artery.

The authors present this study of proximal anterior cerebral arteries in the normal human to provide a clearer basis for strategy in aneurysm surgery. They describe patterns of origin of branches, their subarachnoid course, and parenchymal distribution. Branches that originate from the anterior cerebral artery at the internal carotid bifurcation perfuse the genu and contiguous posterior limb of the internal capsule and the rostral thalamus. Proximal 4-mm branches supply the anterior limb of the internal capsule, the neighboring hypothalamus, anteroventral putamen, and pallidum. The remaining anterior cerebral artery proximal to the communicating artery sends branches to the optic chiasm, the adjacent hypothalamus, and the anterior commissure. Heubner's artery arises directly opposite the anterior communicating artery to supply much of the striatum and internal capsule rostral to the anterior commissure. The anterior communicating artery branches supply the fornix, corpus callosum, septal region, and anterior cingulum. The parenchymal distribution of these end arteries may be surmised from the site of origin named vessels. With this anatomical information one can avoid interruption of blood supply to vital structures when dealing with the anterior cerebral artery and its branches.

Adult↗
PubMed1976

Giant aneurysm of the middle cerebral artery.

A case of a giant aneurysm of the middle cerebral artery, (4.5 X 4.5 X 9.5 CM) presenting as a mass lesion, which was successfully excised is described. This case is compared to the few previous accounts of giant aneurysms of the middle cerebral artery larger than 3 cm in diameter.

Humans↗
PubMed1975

Human epileptic brain Na, K ATPase activity and phenytoin concentrations.

An abnormal flux of monovalent cations may be related to the epileptogenic process in man. One possible mechanism for deranged electrolyte metabolism in epileptic brain is an abnormality in sodium, potassium-dependent adenosine triphosphatase (Na, K ATPase). We found the activity of Na, K ATPase to be significantly less in epileptic human corfex than in nonepileptic cortex. Histological changes have been simultaneously evaluated in epileptic brain. A second membrane-bound enzyme, acetylcholinesterase (AChE), was also assayed as a marker for neuronal membranes and found not to correlate with the epileptogenicity of human brain. In addition, the concentrations of the anticonvulsant compound phenytoin have been determined in the serum and cerebral cortex of epileptic and nonepileptic patients. The ratio of phenytoin in cortex to serum concentration is significantly lower in epileptic patients than in nonepileptic controls.

Acetylcholinesterase↗