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Biomedical subjects

R Mason

Publications and source records attributed to R Mason.

At least 145 records · Page 8Linked to original sources
PubMed1982

Rat cardiac muscle single cell automaticity responses to alpha- and beta-adrenergic agonists and antagonists.

Isolated cardiac muscle cells from neonatal rat ventricular myocardium have both alpha- and beta-adrenergic, positive chronotropic responses, with sensitivity to applied adrenergic agents more than 100 times greater than the intact neonatal heart. These highly sensitive isolated single cells and small groups of cells also reveal partial agonist activity of the alpha-adrenergic antagonist, phentolamine, and the beta-adrenergic antagonist, propranolol. The most likely explanation for the high sensitivity is the lack of a desensitization process that could involve both a desensitization substance and changes in receptors. These experiments suggest that all adrenergic antagonists could possibly show partial agonist activity.

Adrenergic alpha-Agonists↗
PubMed1982

Monoclonal antimacrophage antibodies: human pulmonary macrophages express HLA-DR (Ia-like) antigens in culture.

Study of human macrophages and their role in disease has been hampered by lack of well-characterized tissue macrophages. We describe a simple procedure to obtain viable adherent cells in good yield from resected lung, characterize the cells as greater than 95% macrophage by standard criteria, and document expression of marker properties previously described in rodent macrophages. Human pulmonary macrophages were used to produce monoclonal antibodies and to study expression of HLA-A,B,C, HLA-DR, and related antigens. A new monoclonal mouse antibody, 18, showed restricted binding to macrophages from human lung or blood and to B lymphoid cells, but did not bind to closely related cells. With antibody 18 and other monoclonal antibodies of known specificity, DA2 and Genox 3.53, we showed that a remarkably high proportion of human pulmonary macrophages express HLA-DR framework and DC1 polymorphic determinants in culture. Although the macrophages differed in source and in their state of activation, single cell analysis revealed no heterogeneity in antigen expression.

Antibodies, Monoclonal↗
PubMed1982

Noninvasive evaluation of venous function in chronic venous disease.

Measurements of calf volume changes during treadmill ambulation were taken using mercury-in-Silastic (silicone rubber) strain gauges for noninvasive study of venous function in patients with chronic venous disease. Seventy-four limbs were evaluated: 24 with postphlebitic changes, 26 with superficial varicosities, and 24 normal. Calf volume changes as measured by mercury-in-Silastic strain-gauge plethysmography (MISSGP) during ambulation correlated well (r = 0.8) with simultaneously obtained direct venous pressure measurements. The refill time as measured by MISSGP also correlated with the pressure restoration time (r = 0.8). Patients with moderate-to-severe obstructive patterns as shown by contrast venography were found to decrease their calf volume with MISSGP significantly less (P less than 0.001) than did those patients with minimal or no obstruction of venous outflow as depicted by venography. MISSGP is shown to be a useful method of quantitatively evaluating the efficiency of the calf venous pump, the degree of reflux, and the severity of venous obstruction.

Humans↗
PubMed1982

Isolated popliteal versus distal bypasses for limb salvage.

The results of 54 bypass procedures--22 to an isolated popliteal segment and 32 to an infrapopliteal major calf vessel for limb salvage--were evaluated. After a distal bypass, the elevation of systolic pressure at the ankle was greater than that observed following a bypass to an isolated popliteal segment. However, healing times for ischemic lesions of the foot were comparable for each procedure. Patency and limb salvage rates for saphenous vein and polytetrafluoroethylene isolated popliteal segment bypasses were similar to those obtained with vein bypass grafts to infrapopliteal major calf vessels. In contrast, when polytetrafluoroethylene was used for a distal bypass below the popliteal artery, the failure rate was higher in the first year, with subsequent limb loss. These data suggest that, when a bypass operation is undertaken in the lower extremity for limb salvage, a bypass to an isolated popliteal segment, using either saphenous vein or polytetrafluoroethylene, is preferable to a polytetrafluoroethylene infrapopliteal bypass.

Amputation, Surgical↗
PubMed1981

Cortico-recipient and tecto-recipient visual zones in the rat's lateral posterior (pulvinar) nucleus: an anatomical study.

Afferents to the lateral posterior (pulvinar) nucleus in the rat were studied anatomically using retrograde tracing with fluorescent and horseradish peroxidase techniques. Layer V pyramidal cells in cortical areas 17 and 18a were found to project to the rostral portion of the lateral posterior nucleus (LTP) (the cortico-recipient zone). Cells in the deep superficial grey of the superior colliculus projected to the caudal portion of the LTP (the tecto-recipient zone), the posterior pole of which also received input from cortical area 36. These findings agree with the notion that the rat's LTP is functionally equivalent to regions of the feline and primate pulvinar-complex.

Animals↗
PubMed1981

Differential responsiveness of cells in the visual zones of the cat's LP-pulvinar complex to visual stimuli.

Multiple visual field representations are contained within the feline LP-pulvinar complex; regions differentiated by their afferent and efferent connectivity patterns as the striate-, tecto- and retino-recipient zones. Cell responses from these visuotopic zones were investigated in immobilized cats under N2O/O2 supplemented with pentobarbitone or Althesin, using spot, bar and textured stimuli. Response fields recorded within the LP-pulvinar complex were classified as diffuse, concentric, movement-, direction- or orientation-sensitive. Concentric receptive fields were further classified as sustained (X), transient (Y) or tonic/phasic W-cells. Direction- and movement-sensitive cells predominated in the striate- and tecto-recipient zones, respectively. Motion of noise fields, or noise bars against an identical stationary noise background elicited vigorous responses from cells in the striate zone, many showing a preference for noise stimuli. In contrast, cells from the tectal zone and other divisions of the LP-pulvinar complex were insensitive to noise. The retino-recipient zone at the lateral margin of the pulvinar nucleus was characterized by cells with concentric receptive fields, the majority exhibiting properties similar to W-cells in the LGNd. The evidence supports the notion of functional subdivision within the LP-pulvinar complex corresponding to the visuotopically organized regions defined by their connectivity patterns. Consideration of the retino-recipient zone as an extension of the LGNd-MIN complex is discussed.

Animals↗
PubMed1981

Metabolism of zinc and copper in the neonate: accumulation and function of (Zn, Cu)-metallothionein in the liver of the newborn rat.

1. Measurements were made of the hepatic concentrations and contents of total and thionein-bound zinc and copper in late foetal and newborn rats and of the distribution of these metals between the particulate and soluble components of the liver. 2. The decrease in the hepatic concentration of thionein-bound Zn, which occurred with age after birth, was proportional to the increase in liver weight until the 16th day post partum; thereafter it was greater. 3. Throughout the period from birth to 25 d of age the Zn concentration remained constant in the cytosolic non-thionein fraction (i.e. total cytoplasmic Zn--thionein-bound Zn), but decreased in other compartments of the liver. 4. The same constant concentration of cytoplasmic non-thionein-bound Zn also was observed in animals with reduced total hepatic Zn contents, but normal body-weights, and in 20-d-old Zn-deficient pups. 5. The concentration of thionein-bound Cu increased significantly only between the 6th and 14th day post partum. The age-related variations in Cu contents of the particulate components closely paralleled those in the whole liver, whereas the Cu contents of the cytosolic thionein and non-thionein fractions did not increase appreciably until after the 10th day. 7. It is concluded that the cytosolic non-thionein fraction of newborn rat liver may contain particularly important metabolic sites that require Zn and a major function of Zn-thionein is to regulate the supply of the metal to these sites. As, from birth to 26 d of age, the sum of the concentrations of thionein-bound Zn and Cu was correlated with whole liver Zn, the accumulation of Cu as a soluble metallothionein seems to be a secondary event, dependent on the hepatic Zn concentration.

Aging↗
PubMed1981

Metabolism of zinc and copper in the neonate: accumulation of Cu in the gastrointestinal tract of the newborn rat.

1. The concentration of copper in the rat intestine was found to increase rapidly after birth to a maximum greater than 140 microgram/g wet weight at 2 d of age and then to decline, at first slowly to 90 microgram/g wet weight on day thirteen and then rapidly to 40 microgram/g and 3 . 4 microgram/g wet weight on the 15th and 19th day respectively. The intestinal concentration of Zn, which doubled between 1 d prepartum and 2 d post partum, also fell slowly until 10 d of age, but thereafter remained constant. 2. From the 2nd to the 15th day post partum approximately 60% of the total Cu and 50% of the total zinc in the intestine was located in the soluble fraction of the tissue. Most of the Zn in this fraction was bound by proteins of molecular weights greater than 13700 daltons, whereas most of the Cu was present as an extremely polydisperse complex of lower molecular weight. This complex in the intestine of the 5-d-old rat, in contrast with the soluble proteins of higher molecular weight, did not incorporate either 3H or 35S within 4 h of the administration of L-[4,5-3H]leucine and L-[35S]cystine. 3. The loss of Cu from the intestine between the 13th and 15th day of post-natal age occurred mainly from this complex and was accompanied by the transient appearance of Cu in a fraction of low molecular weight. 4. At 21 d of age the soluble fraction of the intestine contained only a small amount of Cu. This was distributed between two protein fractions, one of which contained Zn and appeared to be a metallothionein. 5. The results are discussed in relation to the control of Zn and Cu absorption.

Aging↗
PubMed1981

Enhancement of plasma alpha-fetoprotein, as measured by sandwich-type radioimmunoassay, and induction of gamma-glutamyl transpeptidase-positive hepatic cell foci in rats fed benzo[a]pyrene.

Male Fischer rats were fed semipurified diets containing 0, 1, 100, and 1000 ppm benzo[a]pyrene (BaP) for 6 or 13 wk. Plasma samples were assayed for alpha-fetoprotein (AFP) by a new sandwich-type radioimmunoassay (RIA) utilizing a special controlled porous-glass solid phase. This procedure is described in detail. Significant AFP elevation (p less than or equal to 0.01) was observed in the highest BaP treatment group after 5 wk of treatment. The 1 and 100 ppm Bap groups exhibited no AFP elevation throughout the study. Liver sections from the 1000 ppm groups had discrete gamma-glutamyl transpeptidase (GGT)-positive foci 10-20 cells in diameter by the 6th wk. GGT-positive foci were not evident in liver sections from the other treatment groups. Thus a high level of dietary BaP appears to rapidly alter rat liver cells, indicating hepatic neoplasia.

Animals↗
PubMed1980

Percutaneous extraction of retained gallstones via the T-tube track-British experience of 131 cases.

Twenty-six hospitals replied to a questionnaire asking for experience in the technique for percutaneous extraction of retained gallstones via the T-tube track. One hundred and thirty-one patients were treated. The overall success rate (complete clearance of residual stones) was 70% and a marked improvement in success rates with increasing operator experience has been demonstrated. The complication rate remains acceptably low during the learning phase. There was no mortality. There were 12 complications (9.2%): pancreatitis (one case), fever (seven cases) and track perforation (four cases). One patient required surgery for complication (track perforation). Variations in technique and management are described.

Bile Duct Diseases↗
PubMed1980

Congenital neurosyphilis and juvenile paresis: a forgotten entity?

Juvenile neurosyphilis is rare and may be arrested or modified in the early stage by antibiotic treatment for intercurrent infections. Inadequate treatment may weaken the signs and symptoms of neurosyphilis so much that a high index of clinical suspicion is required for early and correct diagnosis. It should be remembered, however, that benzathine penicillin does not constitute adequate treatment for neurosyphilis.

Child↗
PubMed1980

Fatal myeloencephalopathy caused by intrathecal vincristine.

Vincristine sulfate was inadvertently given intrathecally to a woman with lymphoma, producing ascending sensory and motor dysfunction followed by encephalopathy and death. Pathologically, neurons were swollen by aggregates of neurofilaments similar to the neurofilaments described in experimental models of vincristine neurotoxicity.

Adult↗
PubMed1980

Speech considerations with maxillary advancement procedures.

Advancement of the maxilla has the potential to cause hypernasal speech, especially in patients with repaired cleft palates. Findings in three patients whose speech was at risk with maxillary advancement procedures are discussed, as well as their management. Diagnostic guidelines for identifying patients whose speech may be adversely affected by maxillary advancement are also presented.

Adolescent↗