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Biomedical subjects

J Pearson

Publications and source records attributed to J Pearson.

At least 163 records · Page 9Linked to original sources
PubMed1988

Electrophysiological correlates of fluid transport in cultured porcine thyroid cells.

Confluent monolayers of cultured porcine thyroid cells transport fluid from the apical to the basal surface, forming circumscribed zones of detachment from the culture dish substrate (domes). The transepithelial potential (TEP), positive on the basal side, was 12.9 +/- 0.4 (S.E.M.) mV (n = 93) under control conditions, increasing to 38.9 +/- 0.3 mV (n = 281) when fluid transport was stimulated by prostaglandin E2 (PGE2; 1 mumol/l). Forskolin (1 mumol/l) and 8-(4-chlorophenylthio) adenosine 3',5'-cyclic monophosphate (0.5 mmol/l) were also effective in increasing TEP. Addition of amiloride in concentrations sufficient to block fluid transport (100 mumol/l) reduced the TEP to 5.8 +/- 0.3 mV (n = 76). Substitution of N-methyl-D-glucamine for sodium in the medium reduced the PGE2-stimulated TEP to 13.4 +/- 0.8 mV (n = 32). Substitution of gluconate for chloride increased the TEP to 40.3 +/- 0.4 mV (n = 160). Removal of bicarbonate or potassium from the medium, or addition of ouabain (200 mumol/l) were also effective in reducing the TEP. In media of low bicarbonate concentration (1 mmol NaHCO3/l), acetazolamide (1 mmol/l) reduced the TEP. Fluid transport by the monolayer as measured by the change in height of domes was increased by PGE2 (1 mumol/l). PGE2-stimulated fluid transport was inhibited by sodium or chloride ion substitution, bicarbonate removal or the addition of ouabain (200 mumol/l) or amiloride (100 mumol/l). It was concluded that fluid transport in thyroid monolayers is mediated by rheogenic sodium transport with chloride transport being passive, electrogenically coupled to sodium transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1988

Extensive loss of human DNA accompanies loss of antibody production in heteromyeloma hybridoma cells.

Several human B-cell hybridomas produced by fusion with the mouse X human partner (SHM-D33), and previously assessed for stability of human monoclonal antibody production, have now been assessed for (1) presence of structural genes coding for human immunoglobulin, (2) amount of human DNA, and (3) the rate of loss of human DNA. We found that the proportion of human DNA in clonal populations derived from parental hybridoma populations was extremely variable. Human DNA content varied from 20% to 50% in antibody-producing hybridoma clones. However, loss of antibody production is accompanied by loss of structural immunoglobulin genes and an accelerated loss of greater than 95% of the human component of the hybridoma DNA. In one hybridoma clone, the measured rate of depletion of cellular human DNA was dramatically increased soon after loss of antibody production. These data suggest that stability of human antibody production in hybridomas is dependent on the ability of hybridomas to retain human DNA, and that there is clonal heterogeneity with respect to this ability within hybridoma populations.

Animals↗
PubMed1987

Neurotensin immunoreactive neurons in the human infant diencephalon.

Neurotensin-like immunoreactive (NT-IR) neurons are present in discrete subregions of the anterior, medial and lateral thalamic nuclear groups of the human infant brain. The pulvinar is notably rich in such cells. Smaller numbers of cells are present in the ventral group, centromedian nucleus, reticular nuclei and intralaminar nuclei. Neurotensin immunoreactive axons accumulate dorsally in the thalamus and cross the deep white matter. The cerebral cortex contains a rich network of NT-IR axons. The subthalamic nucleus is rich in NT-IR neurons. Within the hypothalamus NT-IR perikarya are present in parts of the lateral and tuberal regions and in the lateral mammillary area. NT-IR axons are widespread being particularly prominent in parts of the tuberal region and the mammillary body.

Diencephalon↗
PubMed1987

Substance P- and enkephalin-immunoreactive neurons in the hippocampus and related areas of the human infant brain.

Neurons strongly immunoreactive for substance P are present as subpopulations in the stratum oriens, pyramidal layer and polymorphic layer of the hippocampus of the human infant. Substance P immunoreactive terminals are numerous on other neuronal cell bodies in the polymorphic layer and over pyramidal cells of the subiculum and the CA1, 2 and 3 regions. There is a high density of substance P-immunoreactive axons in the granular layer. Enkephalin immunoreactive neurons are relatively few in number and are present in the polymorphic and pyramidal layers. The results indicate that substance P probably plays a major role in short range circuits in the human hippocampus and that intrinsic enkephalin neurons probably play a relatively minor role.

Brain Mapping↗
PubMed1987

Holter monitoring in patients with mitral stenosis and sinus rhythm.

To determine the type and frequency of supraventricular arrhythmias in patients with mitral stenosis and sinus rhythm we studied 63 such patients, mean (sd) age 48.8 (8.2) years, by 24 hour ambulatory ECG monitoring. Thirty-five patients (55.6%) had supraventricular tachyarrhythmias. Twenty-five (39.7%) had paroxysmal atrial tachycardia, 14 (22.2%) atrial fibrillation, 8 (12.7%) multifocal atrial tachycardia and 5 atrial flutter. Ninety-five per cent (101) of episodes were asymptomatic and 96% non-sustained. Supraventricular premature beats occurred in 59 patients with couplets and triplets in 40 (63.5%) and 28 (44.4%), respectively. Frequent supraventricular premature beats, couplets, triplets and episodes of paroxysmal arrhythmias were commoner in patients greater than 50 years. Ectopic atrial rhythms with varying P wave morphology occurred in 12 patients (19%). Nine patients (14.3%) had suffered systemic embolic episodes. We conclude that supraventricular ectopic and tachyarrhythmias occur frequently in patients with mitral stenosis and sinus rhythm and that most paroxysms are non-sustained and asymptomatic.

Adult↗
PubMed1987

Survival and transport of bacteria in egg washwater.

An evaluation of methods for monitoring the quality of water used to wash eggs at grading stations was undertaken to improve maintenance of bacterial viability during overnight sample transport. Bacterial content of samples at analysis would then better reflect conditions at the time eggs were washed. The interactive effects of temperature and the highly alkaline water conditions upon viability were the subjects of this study. Nine transport methods were examined for their efficacy in recovering total and coliform bacteria from recycled water used to wash eggs, and these were compared with samples analyzed at two commercial egg grading stations. Samples were shipped under test to the laboratory for analysis the following day. The survival of Staphylococcus aureus and Escherichia coli was also examined, but in a synthetic washwater matrix under various combinations of temperature (6 to 32 degrees C) and pH (9.5 to 10.5) to determine whether there was likely to be a different response to variations in transport treatment among gram-positive and -negative bacteria. S. aureus was much more resistant to the lethal effects of high pH and moderate temperature than E. coli. These results indicated that samples of high pH should be held (transported) at less than or equal to 13 degrees C to optimize bacterial survival. Considering cost, ease of manipulation, and the ability to protect both coliforms and the bacterial population as a whole, the method of choice for transport of industrial samples was the direct addition of washwater to containers in which powdered KH2PO4 and Na2S2O3 had been placed to yield final concentrations, when dissolved, of 0.2 and 0.05% (wt/vol), respectively.

Animals↗
PubMed1986

Neurotensin immunoreactive structures in the human infant striatum, septum, amygdala and cerebral cortex.

Neurotensin immunoreactive (NT-IR) neuronal perikarya are present in small numbers in the bed nucleus of the stria terminalis, lateral olfactory stria, substantia innominata, caudate nucleus and putamen of the human infant forebrain. Larger numbers of perikarya are present in the amygdala and related structures. NT-IR axons are present in the medial septal area, bed nucleus of the stria terminalis, caudate nucleus, putamen and amygdala. The cerebral cortex contains a rich network of NT axons with an accentuation in layer II. This network appears to be derived from bundles of axons which traverse the deep white matter from the thalamus.

Amygdala↗
PubMed1986

Neurotensin immunoreactivity in the human cingulate gyrus, hippocampal subiculum and mammillary bodies. Its potential role in memory processing.

Neurotensin immunoreactive neurons comprise the majority of large perikarya in the human subiculum and project axons to the alveus, fimbria, fornix and neuropil of the mammillary bodies. These regions are prominently involved in conditions such as Wernicke's and Alzheimer's disease in which memory is impaired. Neurotensin has potential significance as a peptide in a human brain circuit which may serve a role in memory processing.

Female↗
PubMed1986

A neurotensin-immunoreactive pathway from the subiculum to the mammillary body in the rat.

The existence of a neurotensin-like immunoreactive (NT-IR) pathway from the subiculum to the mammillary body was demonstrated in very young rats using immunocytochemistry, knife cut, electric lesion and retrograde tracer techniques. Unilateral hemitransection of the dorsal fornix caused a marked reduction of NT-IR fibers in the ipsilateral mammillary body. Unilateral electric lesion of the subiculum also resulted in ipsilateral reduction of NT-IR fibers in the mammillary body. Biotin-wheat germ agglutinin (B-WGA), injected into the mammillary body, labeled neurons in the ipsilateral subiculum which were shown by double staining to have NT-IR cytoplasm. These findings demonstrate the presence of a major NT-IR fiber pathway from the subiculum to the mammillary body via the fornix.

Animals↗
PubMed1986

Dynamic interaction of 111indium-labeled monoclonal antibodies with surface antigens of solid tumors visualized in vivo by external scintigraphy.

Two 111indium-labeled murine monoclonal antibodies (MoAb), D3 and 9.2.27, directed to tumor antigens of L-10 hepatocarcinoma and human melanoma, respectively, selectively localized antigen-positive target cells in guinea pigs and nude mice. The fate of MoAb differed in the two antigen-antibody systems after reacting with their corresponding tumor antigens in vivo as reflected by patterns of distribution and turnover in vivo. The 9.2.27 localized in melanoma xenograft in nude mice after intravenous administration with slow loss from tumor but more rapid loss from normal tissues and thus demonstrated optimal imaging of small tumors (approximately equal to 5 mm) between 3 and 6 days after injection of the radiolabeled antibody. In contrast, D3 demonstrated a biphasic localization in guinea pig L-10 hepatocarcinoma with a maximal activity on the 2d day after administration and showed rapid loss from both tumor and normal tissues. Nonspecific localization of antibodies in liver and in kidney was found both in syngeneic (nude mice) and xenogeneic (guinea pig) hosts but was more pronounced in the xenogeneic species. These results indicate that the nature of the antigen-antibody interaction may be of importance in selecting MoAb for both diagnosis and therapy of malignant diseases.

Animals↗
PubMed1985

Adrenergic neurons in human brain demonstrated by immunohistochemistry with antibodies to phenylethanolamine-N-methyltransferase (PNMT): discovery of a new group in the nucleus tractus solitarius.

Adrenaline neurons in human brain were demonstrated by immunohistochemistry using antibody to phenylethanolamine-N-methyltransferase (PNMT), the final enzyme in the pathway of adrenaline synthesis, using fixed frozen sections and a highly sensitive free floating technique which utilizes metallization. Small densely packed PNMT-immunoreactive neurons were observed to form a nucleus lying just ventrolateral to the area postrema and in the dorsal part of the nucleus tractus solitarius. Larger adrenergic neurons were also present in and around the lateral reticular nucleus and in relationship with the dorsal motor nucleus of the vagus in regions equivalent to the C1 and C2 groups in rats. Longitudinally oriented PNMT-positive axons constitute a subset of tyrosine hydroxylase-immunoreactive axons in the dorsomedial reticular formation.

Adrenergic Fibers↗
PubMed1985

Differential susceptibility of cultured neural cells to the human coronavirus OC43.

By using cell-type-specific markers and neural cultures derived from various areas of the nervous system, it has been possible to identify various interactions between OC43 virus and mouse oligodendrocytes, neurons, astrocytes, and fibroblasts. Neurons derived from dorsal root ganglia produced viral antigen and infectious virus. Astrocytes and fibroblasts both produced viral antigen but not infectious virus. Oligodendrocytes produced neither infectious virus nor viral antigen. Human embryo brain cells, including astrocytes, were susceptible to OC43 infection but did not produce infectious virus.

Animals↗
PubMed1985

Work-rest periods: their effects on normal physiologic response to isometric and dynamic work.

Heart rate (HR) and blood pressure (BP) responses to repeated dynamic and combined dynamic and isometric work bouts of 30 sec, 2 min, and 6 min with equal rest periods at 40% and 80% of Vo2max was studied in five healthy men and five healthy women. Total work duration for each experimental condition was 24 min. The treadmill was used for dynamic work. Subjects pushed a bar horizontally while on the treadmill at 20% of their maximal voluntary strength for isometric work. Results showed that work performed at 40% of Vo2max in 30 sec bouts compared to 6 min bouts reduced HR, BP and the double product (BP X HR) by 11%, 4%, and 14%, respectively. Work performed at 80% of Vo2max in 30 sec bouts of repeated work or rest compared to the 6 min bouts resulted in reducing HR, BP, and double product 28%, 15%, and 39%, respectively. Addition of the isometric load did not significantly change the results. This study suggests that cardiac patients may be able to perform more work safely if it is carried out in short periods alternating with rest periods of equal duration.

Adult↗