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Biomedical subjects

J Mason

Publications and source records attributed to J Mason.

At least 163 records · Page 9Linked to original sources
PubMed1992

Molecular cloning and nucleotide sequence of cDNA encoding a functional murine low-density-lipoprotein receptor.

The low-density-lipoprotein (LDL) receptor is an important mediator of mammalian cholesterol metabolism; its congenital absence in humans is characterized by hypercholesterolemia, atherosclerosis, and coronary artery disease. We report here the identification and cloning of a cDNA encoding the murine LDL receptor. The cDNA insert is 4467 base pairs in length and the deduced amino acid sequence bears 78.2% homology with the reported human sequence. This murine cDNA was subcloned into a retroviral-based expression vector, LmLSN1, and transfected into 3T3 cells. The production of functional LDL receptor was confirmed by ligand binding of DiI-LDL cholesterol.

Amino Acid Sequence↗
PubMed1992

The effect of cyclosporin on renal function.

The depression of renal function caused by cyclosporin does not generally reflect permanent kidney damage but is caused by a reversible vasoconstriction, with no relevant changes in tubular function. Serum creatinine may remain within the normal range during therapy, but any decline in renal function can be detected by a rise in serum creatinine above the baseline value. Measurements of glomerular filtration rate before and during therapy have shown the degree of renal dysfunction in individual patients to correspond to their rise in serum creatinine. The cause of renal vasoconstriction is uncertain but animal experiments have highlighted several possibilities. These include: (1) albumin leakage with circulatory volume contraction; (2) enhanced Ca mobilization in contractile cells; (3) activation of a renin-like enzyme in vessel walls; and (4) renin accumulation in the renin-producing cells of the afferent arteriole. Such mechanisms, although seeming to operate at different doses, may act in unison at high doses, when renal function is most severely depressed.

Animals↗
PubMed1992

Tracheostomy self care: the Nottingham System.

Tracheostomy self care at home can be a problem for some patients. The Nottingham System attributes a competence ratio to each patient. Those liable to develop problems can be identified early and the appropriate support provided. The Nottingham System is described.

Humans↗
PubMed1992

Effect of cyclosporine on endothelial albumin leakage in rats.

Short-term treatment of rats with cyclosporine (cyclosporine A [CsA]; Sandimmune) results in a marked reduction in intravascular plasma volume, a factor that might contribute to the renal dysfunction associated with this potent immunosuppressant. To examine the role of plasma extravasation in CsA-induced hypovolemia, intravascular plasma volumes (PV), blood volumes, [125I]albumin disappearance, and changes in hematocrit (Hct) were measured in Inactin-anesthetized rats subjected to minimal surgery. The rats were treated for 3 wk with either 25 mg/kg/day of CsA s.c. or vehicle. Plasma creatinine and urea were significantly elevated, and magnesium was reduced in the CsA group (N = 6) as compared with controls (CON) (N = 6). CsA treatment had no effect on urinary protein and albumin excretion. Blood volume was significantly lower in CsA than in CON (8.4 +/- 0.5 versus 10.6 +/- 0.3 mL/100 g body wt) as was PV (4.3 +/- 0.2 versus 5.5 +/- 0.2 mL/100 g body wt). Two hours after injection, plasma [125I]albumin concentration had fallen by 41 +/- 4% in CsA versus 23 +/- 5% in CON. Because Hct, and, hence PV, was unchanged in both groups during these 2 h, these data indicate enhanced endothelial albumin leakage in the CsA group. In two additional groups of six rats each, acute volume expansion with fresh whole blood (2 mL/100 g body wt) resulted in extravasation of plasma. Hct rose by 8.0 +/- 0.2% in CsA versus 3.8 +/- 0.2% in CON after 150 min, corresponding to 27 +/- 3 and 15 +/- 2% decreases in total PV, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Evaluation of an enzyme-linked immunosorbent assay for detection of antibodies to vesicular stomatitis virus in cattle in an enzootic region of Mexico.

An ELISA was compared with the plaque-reduction serum neutralization (PRSN) test, for detection of vesicular stomatitis virus (VSV) antibodies in cattle in a vesicular stomatitis enzootic region of Mexico. A total of 325 bovine serum samples were screened for VSV antibodies. The PRSN test was performed, using Vero cells. The ELISA contained gradient-purified VSV Indiana (Lab strain) and VSV New Jersey (Hazelhurst) as the antigens. Regression analysis and weighted kappa statistic were used to estimate measures of agreement between the 2 assays for detection of VSV antibodies. The ELISA method proved useful for serodiagnosis of vesicular stomatitis. The ELISA and PRSN test results were highly correlated for detection of VSV antibodies.

Animals↗
PubMed1992

Assessment of liver copper status in cattle from plasma copper and plasma copper enzymes.

Copper status determined by liver biopsy was also assessed by 3 plasma parameters: total plasma copper (Cu) as well as ceruloplasmin (Cp) and amine oxidase E.C.1.4.3.6. (AO) activities. While 14 out of the 98 cattle, all kept in field conditions, had liver copper levels of less than 20 mg/kg only 5 of these could be distinguished by low plasma Cu and 3 by low Cp activity. In addition, some animals with apparently adequate liver copper had relatively low plasma Cu values, ca 0.5-0.6 mg/l. None of the cattle had decreased AO activity. When all 3 plasma parameters were combined in the form [AO] divided by ([Cp] x [Cu]), detection of the low liver copper was improved in that 9 out of 14 could be distinguished, whereas animals with more than 20 mg/kg DM liver Cu could not. It is suggested that this relationship, tentatively called an index, would merit examination in other situations, since it might provide a better guide to copper status and indicate whether copper repletion therapy was worthwhile.

Amine Oxidase (Copper-Containing)↗
PubMed1992

General practice estimates of the prevalence of common chronic conditions.

This study measured the prevalence of chronic medical conditions in 4,549 middle aged persons attending three large general practices in Dublin over the course of a calender year. The prevalence of the following conditions were measured: coronary heart disease, hypertension, stroke, diabetes, asthma, chronic bronchitis, rheumatic disorders, dyspepsia, depression, anxiety disorders, psychoses, and cancer. In order to obtain a valid denominator for the study a second community based study was carried out in the same areas to determine what proportion of persons visit their general practitioner over the course of a year. Overall 40.5% of males and 44% of females suffered from a least one of the twelve conditions, with rheumatic disorders having the highest prevalence (14.5%) and psychotic disorders the lowest (0.75%).

Adult↗
PubMed1992

The interactions of penicillamine with copper in vivo and the effect on hepatic metallothionein levels and copper/zinc distribution: the implications for Wilson's disease and arthritis therapy.

D-penicillamine does not remove copper from metallothionein, but it has been suggested that it may increase hepatic metallothionein levels. D-penicillamine was shown to increase rat hepatic metallothionein levels; however, the effect was dependent on an interaction with copper. The drug accelerated the excretion of exogenous copper but increased the amount retained on metallothionein. This interaction of penicillamine and copper also provoked changes in the distribution of zinc and in particular an increase in the heat-stable cytosol zinc fraction. In contrast, thiomolybdates were much more effective in eliminating exogenous copper and even removed copper that was already bound to metallothionein; thus, the copper level in the heat-stable cytosol fraction decreased. The observations support the view that patients with Wilson's disease may not be truly "decoppered" but that treatment with d-penicillamine is effective because the accumulated copper in the liver is bound in a nontoxic form by the increased metallothionein. The results explain why cessation of treatment is dangerous. The results may also partially explain the effectiveness of D-penicillamine copper chelates as antiinflammatory drugs.

Animals↗
PubMed1992

An explanation for the difference in general practitioner consultation rates between GMS and non-GMS patients.

This study compares annual consultation rates between 3,111 General Medical Services and private patients, and their family doctors in three large general practices in Dublin. Visiting rates were substantially different between practices and between GMS and private patients. However, GMS patients were older and had 50% more chronic illnesses. When the effects of age and illness were controlled in a multiple regression model, GMS status accounted for less than 5% of the variation in visiting rates. GMS patients consult their practitioners in proportion to their medical need.

Adult↗