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M W Hougland

Publications and source records attributed to M W Hougland.

11 recordsLinked to original sources
PubMed1987

Expression of asialo GM1 on a subset of adult murine thymocytes: histological localization and demonstration that the asialo GM1-positive subset contains both the functionally mature and the proliferating thymocyte subpopulations.

A small population (10 to 14%) of adult murine thymocytes expresses the glycolipid asialo GM1 (aGM1). Flow cytometric analysis of the aGM1+ cells present in thymus demonstrates the expression of a mature or medullary phenotype by 50% of the aGM1+ cells. Analysis of cytotoxic T lymphocyte precursor activity, proliferative capacity, and IL 2 production displayed by aGM1+ and aGM1- thymocyte fractions isolated by cell sorting indicates that these functional compartments of the thymus are contained within the aGM1+ subset. The aGM1+ population also contains virtually all mitotically active thymocytes, as measured by incorporation of bromodeoxyuridine. The immature IL 2 receptor-bearing thymoblasts are also included in the aGM1+ population. Immunohistochemical labeling of thymic tissue sections reveals that the majority of aGM1+ cells are located in the medulla. Clusters of aGM1+ cells are found scattered throughout the cortical and subcapsular areas. The aGM1+ population therefore contains the functionally mature thymocytes as well as some immature thymocytes, particularly those that are mitotically active. It is suggested that the aGM1+ subset of thymocytes represents those cells that are mature or actively maturing. This hypothesis is discussed in the context of current concepts of intrathymic T cell differentiation pathways.

Animals↗
PubMed1987

Distribution of muscarinic receptors and acetylcholinesterase in the rat heart.

Experiments were performed to determine the degree of overlap in the distribution of muscarinic receptors and cholinergic innervation of the rat heart. Localization of muscarinic receptors was determined by autoradiography with [3H]quinuclidinyl benzilate. Adjacent sections were stained for acetylcholinesterase to determine innervation. The distribution of muscarinic receptors and cholinergic innervation overlapped in cardiac parasympathetic ganglia, nodal tissue, His bundle-Purkinje system, vena cava and pulmonary veins. Cholinergic innervation to the right atrium was greater than to the left atrium while muscarinic receptor density was equal in the two atria. Innervation of the ventricles was confined primarily to the base of the right ventricle. A low density of muscarinic receptors was observed throughout the ventricles. Neither cholinergic innervation nor muscarinic receptors were detected in the pulmonary trunk, ascending aorta or cardiac valves. Muscarinic receptors and cholinergic innervation in the nodal regions, ventricular conduction system and myocardium probably mediate negative chronotropic, dromotropic and inotropic effects of vagal nerve stimulation. Muscarinic receptors at sites not containing cholinergic innervation may be associated with noradrenergic nerves of the myocardium.

Acetylcholinesterase↗
PubMed1986

Innervation of guinea pig heart by neurons sensitive to capsaicin.

To determine the origin of non-vagal afferent fibers innervating the heart of guinea pigs, capsaicin was injected into the ventricular myocardium to induce depletion of substance P (SP). The lower cervical, upper thoracic and lumbar spinal ganglia, as well as the left atrium and base of ventricles, were assayed for SP depletion by using the enzyme-linked immunosorbent assay (ELISA) and immunohistochemical procedures. Capsaicin affected spinal ganglia from the 3 regions differently. The substance P level in lumbar spinal ganglia remained fairly constant, while the level of SP from cervical and thoracic regions declined significantly. At the maximal depletion dosage (173 micrograms of capsaicin/kg), SP concentration decreased 72.3% in cervical spinal ganglia, 45.5% in thoracic ganglia and 56.1% in the atrium. The lack of SP depletion in lumbar ganglia indicates that capsaicin acted locally on cardiac afferents rather than systemically. Data from this study suggest that capsaicin-sensitive neurons of the heart have cell bodies in the lower cervical spinal ganglia as well as in the upper thoracic spinal ganglia.

Animals↗
PubMed1985

Evaluation of simultaneous teaching of extremities in gross anatomy program.

A gross anatomy program was designed to expose medical students to all areas of the body but shortened the dissection time on the extremities by having half the class dissect either the upper or lower extremity and then study the opposite extremity already dissected by other classmates. The program has been used for six years and was evaluated via an analysis of covariance by comparing the intramural examination performance on both the dissected and undissected extremities. There was no statistical difference in the students' performances regardless of the extremity dissected. The program was also evaluated externally by student performance on Part I of the examinations of the National Board of Medical Examiners. Students (n = 191) performed at the national average (69 percent) on all gross anatomy questions and on those questions pertaining to either extremity (66 percent). The program has efficiently utilized laboratory time with no measurable change in performance by six medical classes.

Anatomy↗
PubMed1984

Human lung tryptase. Purification and characterization.

Human lung tryptase, a mast cell-derived trypsin-like serine protease, has been isolated from whole human lung tissue obtained at autopsy. Increased yields from this purification process have allowed extensive characterization of the enzyme. One of the critical steps in the purification scheme is the use of a linear heparin gradient to elute active material from cellulose phosphate. Gel filtration studies in 1.0 M NaCl yielded an apparent Mr = 135,000, and subsequent electrophoresis on sodium dodecyl sulfate-polyacrylamide gels demonstrated the presence of two active species with apparent Mr = 30,900 and 31,600. Enzymatic activity was sensitive to NaCl concentrations above 0.05 M and was only 50% in 0.15 M NaCl, decreasing to 18% in 0.6 M NaCl. The effects of synthetic and natural inhibitors have also been studied, confirming the enzyme's trypsin-like characteristics and demonstrating that naturally occurring serum inhibitors are incapable of diminishing its activity. A complete amino acid analysis showed a high tryptophan content. Lastly, antisera to human lung tryptase have been generated, and the immunological identity of active fractions has been investigated as well as the localization of the enzyme to the mast cell granule by immunohistochemical staining.

Amino Acids↗
PubMed1983

Cross-sectional anatomy: preparation of teaching specimens.

Forty cross sections of a male cadaver were prepared for a Continuing Medical Education Seminar and have been used in teaching programs for the past 3 years. The sections are easy and inexpensive to construct and can be maintained with a minimal amount of effort.

Anatomy↗
PubMed1982

Quantitation of sulfhydryl groups on erythrocytes in polycythemia vera.

The number of sulfhydryl groups on the surface of intact erythrocytes from patients with polycythemia vera is significantly less (34%) than those from control subjects. Sulfhydryl groups were measured indirectly by reversibly blocking -SH groups with the thiol reagent, 6,6'-dithiodinicotinic acid, which forms stable mixed disulfides on the surface of erythrocytes. Glutathione was used to break the disulfides and release thione into the supernatant. Thione was then quantitated spectrophotometrically.

Erythrocyte Membrane↗
PubMed1978

Canine kidney cells: I. Neutral lipids, phospholipids and fatty acids of SV40 transformed canine kidney cells in suspension and monolayer culture.

Differences in lipid composition and the effects of monolayer and suspension culture on SV40 virus transformed canine kidney cells and their plasma membranes were studied. Plasma membranes from monolayer and suspension cultures of SV40 transformed canine kidney cells were isolated by the Warren fluorescein-mercuric acetate technique. Free cholesterol was the major neutral lipid extracted from the whole cells and plasma membranes of all these cultures. Triglyceride increased about 6- to 50-fold in suspension grown whole cells and their plasma membranes compared to those from monolayer cultures. The mu moles of total neutral lipids and phospholipids are elevated in plasma membranes compared to whole cells from monolayer cultures but are similar in suspension cultures. The distribution of fatty acids in the major lipid classes of plasma membranes and whole cells generally follow the composition of calf serum used in the culture media. INDEX WORDS: SV40, plasma membranes, transformed cells, canine kidney cells, neutral lipids, phospholipids, monolayer culture, suspension culture.

Animals↗
PubMed1978

Canine kidney cells. II. Neutral lipids, phospholipids and fatty acids of Madin-Darby canine kidney cells in suspension and monolayer culture.

Differences in lipid composition and the effects of monolayer and suspension culture were studied in Madin-Darby canine kidney cells and their plasma membranes isolated by the Warren fluorescein-mercuric acetate technique. Unesterified cholesterol was the major neutral lipid extracted from the whole cells and plasma membranes of cultures except for suspension-grown whole cells which had triglyceride as their major neutral lipid. Triglyceride increased about 7- to 20-fold and glycerol ethers increased about 3- to 20-fold in suspension grown whole cells and their plasma membranes compared to those from monolayer cultures. Total quantities of phospholipids are similar in whole cells of both cultures. Plasma membranes from monolayer cultures have about 1.4-fold more total phospholipids than those from suspension cultures. The distribution of fatty acids in the plasma membranes and whole cells generally follow the composition of calf serum used in the culture medium. However, the phospholipids of plasma membranes from monolayer cultures had substantially higher values for C18 unsaturated fatty acids and somewhat lower values for palmitoleic acid than the values for the fatty acids in calf serum. Also, the phospholipids of suspension-grown whole cells had substantially higher values for lauric acid and lower values for C18 unsaturated fatty acids when compared to calf serum.

Animals↗