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W Martin

Publications and source records attributed to W Martin.

At least 253 records · Page 14Linked to original sources
PubMed1985

Specificity of P2-purinoceptor that mediates endothelium-dependent relaxation of the pig aorta.

ATP (EC50 5 microM) induced endothelium-dependent relaxation of the isolated aorta of the newborn pig, but the other naturally occurring nucleotides CTP, GTP, ITP and UTP were more than 100 times less potent. 2-Methylthio-ATP (EC50 0.1 microM) was 50 times more potent than ATP, but the unnatural enantiomers L-ATP and 2-methylthio-L-ATP were virtually inactive. beta,gamma-Imido-ATP and beta,gamma-methylene-ATP, both of which are resistant to degradation by ectonucleotidases on cultured pig endothelial cells, were much less potent than ATP. ADP beta S, which is also resistant to degradation, was equipotent with ATP at low concentrations but achieved a maximal relaxation of only 50% that of ATP. The Rp and Sp diastereoisomers of ATP beta S were both equipotent with ATP at low concentrations and both achieved approximately 60% of the maximal relaxation of ATP. The Rp and Sp diastereoisomers of ADP alpha S were both less potent than ATP and achieved only approximately 25% of the maximal relaxation of ATP. These results demonstrate that the P2-purinoceptor mediating endothelium-dependent relaxation of the pig aorta exhibits a high degree of specificity for the adenine base, is stereospecific for the D-ribofuranosyl moiety, requires a phosphate chain of 2 or 3 units but is not stereoselective toward this phosphate chain. These structural requirements have some features in common with the P2-purinoceptors on smooth muscle and on platelets, and are quite different from those of the ectonucleotidases present on pig endothelial cells in culture.

Adenosine Triphosphate↗
PubMed1985

"V" shaped predens space.

"V" shaped widening of the predens space (PDS) in flexion can be a worrisome finding in trauma patients, possibly representing injury to the transverse ligament. These patients may also show widening of the C-1/C-2 interspinous distance. We think this appearance is usually due to increased flexion mobility at the atlantoaxial level with developmental elongation or laxity of the cranial end of the transverse ligament and/or the posterior ligamentous complex. Tearing of only the cranial end of the transverse ligament must be extremely rare, if it occurs at all; there is no reported proven case. Tearing of only posterior ligaments seems possible and should be evaluated clinically.

Adolescent↗
PubMed1985

Interactions of endothelial cells and smooth muscle cells of arteries.

Relaxation of selected isolated arteries by acetylcholine, bradykinin, and certain other vasodilators is mediated by a factor released from endothelial cells. Relaxation by the factor (chemical identity still unknown) is accompanied by an increase of cyclic GMP. The finding that hemoglobin inhibits both endothelium-dependent relaxation and the increase in cyclic GMP may have pathophysiologic relevance.

Animals↗
PubMed1985

Blockade of endothelium-dependent and glyceryl trinitrate-induced relaxation of rabbit aorta by certain ferrous hemoproteins.

We have reported previously that hemoglobin inhibits endothelium-dependent and glyceryl trinitrate-induced relaxation in the rabbit aorta. In this study we have examined the effects of other ferrous and ferric hemoproteins on endothelium-dependent and glyceryl trinitrate-induced relaxation to determine whether they also share the inhibitory properties of hemoglobin. Of the two ferrous hemoproteins tested, myoglobin (1-10 microM) abolished the endothelium-dependent relaxation induced by acetylcholine and produced a concentration-dependent reduction in the endothelium-independent relaxation induced by glyceryl trinitrate, in a manner similar to that reported previously for hemoglobin, but reduced cytochrome C was completely ineffective. The ferric hemoproteins methemoglobin (10 microM) and metmyoglobin (40 microM) produced only a slight inhibition of acetylcholine-induced relaxation. Methemoglobin (10 microM) also blocked only slightly the endothelium-dependent relaxation induced by the ionophore A23187 and had no effect on glyceryl trinitrate-induced relaxation. The inhibitory effects of these hemoproteins were reflected in their respective effects on the stimulation of cyclic GMP levels; thus, myoglobin (10 microM) inhibited the endothelium-dependent rise in cyclic GMP content induced by acetylcholine, as was found previously for hemoglobin, but methemoglobin (10 microM) was much less effective. The effectiveness of hemoglobin and myoglobin and the ineffectiveness of reduced cytochrome C in blocking the relaxations induced by acetylcholine and glyceryl trinitrate might suggest that only ferrous hemoproteins with ligand binding sites are inhibitory.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1985

PGM1 system. Report on the international workshop, October 10-11, 1983, Munich, West Germany.

Because of the increase in the number of PGM1 polymorphisms and the existence of four distinct nomenclatures for expressing subtypes by isoelectric focusing, a nomenclature workshop was held in 1983 to compare variants and arrive at a single method for reporting PGM1 data. A total of 30 rare variants were identified and the recommended method for expressing the four common alleles is PGM1*1A, PGM1*1B, PGM1*2A, and PGM1*2B.

Alleles↗
PubMed1985

Selective blockade of endothelium-dependent and glyceryl trinitrate-induced relaxation by hemoglobin and by methylene blue in the rabbit aorta.

Hemoglobin at 1 microM reduced and at 10 microM abolished the endothelium-dependent relaxation induced by acetylcholine or by A23187 in rabbit aortic rings. Similarly, methylene blue at 10 microM reduced and at 50 microM abolished relaxation induced by acetylcholine and by A23187. Furthermore, hemoglobin (1-10 microM) and methylene blue (10-50 microM) each induced a dose-dependent inhibition of the endothelium-independent relaxation produced by glyceryl trinitrate, but neither had any effect on the relaxation produced by isoproterenol. The inhibitory effects of hemoglobin and methylene blue may be due to blockade of guanylate cyclase, as the rises in cyclic GMP content which accompany relaxation induced by acetylcholine, A23187 or glyceryl trinitrate were abolished. Isoproterenol-induced relaxation took place with no change in cyclic GMP content. Hemoglobin and methylene blue appear therefore to inhibit selectively vaso-relaxation induced by agents which increase cyclic GMP levels. Hemoglobin and methylene blue augment tone in aortic rings, particularly when endothelial cells are present, suggesting that the endothelium-derived relaxing factor (EDRF) might be released spontaneously in low concentrations. The possibility that hemoglobin inhibits endothelium-dependent and glyceryl trinitrate-induced relaxation by binding EDRF and nitric oxide, respectively, is discussed together with the proposal that methylene blue might produce its effects by oxidizing a component of guanylate cyclase, possibly a ferrous heme group linked to the enzyme molecule. Methylene blue might, in addition, interact directly with EDRF.

Acetylcholine↗
PubMed1985

Color discrimination as a function of saturation, field size, and adaptation level.

The purpose of our research was to investigate color discrimination under conditions of ambient illumination that may reduce CRT display saturation and contrast. Our research measured both the variability of color matching and the offsets from a match necessary for a 100% discrimination difference. We did this for four dominant wavelengths each at five saturation levels. Our subjects were tested at low, medium, and high adaptation levels for both large and small test stimulus sizes. In general, our results for the low luminance color matching conditions are in agreement with the published literature. For the high luminance and small field conditions, our data suggest that color discrimination should not be predicted from the 1960 CIE Uniform Chromaticity Space data. Color discrimination varies dramatically with dominant wavelength; reds and greens are more difficult to discriminate than yellows and yellow-greens.

Adaptation, Physiological↗
PubMed1985

The effects of left atrial and left ventricular cannulation on left ventricular function.

A study in anesthetised dogs was undertaken to investigate the immediate effects of cannulation of the heart for left heart bypass on left ventricular function. Twenty-six mongrel dogs were studied. In the first group of 13 dogs (Group A), left atrial cannulation was performed through the atrial appendage and in the second group of 13 dogs (Group B), the left ventricular apex was also cannulated. Systemic blood pressure, heart rate, left atrial pressure, left ventricular end diastolic pressure and dP/dT showed no difference in left ventricular function between Groups A and B. Global ejection fraction (EF) measured by injection of technetium99m-labelled human serum albumen with gated left ventricular imaging, showed no significant difference between the two groups but analysis of the regional contribution to global EF in Group B dogs demonstrated a significant reduction in left ventricular function at the site of ventricular cannulation (P less than 0.05). These findings, together with other reported disadvantages of left ventricular cannulation, suggest that the left atrium is the preferred site for cannulation when left heart bypass is required. Many reports attest to the value of mechanical circulatory support in patients with ventricular dysfunction who cannot be weaned from cardiopulmonary bypass (2, 4, 10, 11, 15). Initial support is commonly provided by an intra-aortic balloon pump but, in more severe cases, use of a left ventricular assist device may be warranted. More recently, such devices have also been employed in the management of patients with cardiogenic shock refractory to medical therapy (10).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Cold pressor induced changes in regional left ventricular wall motion: specific but insensitive for coronary artery disease.

The incidence of new regional abnormalities of left ventricular wall motion induced by a peripheral cold stimulus has been examined in 75 patients who all underwent coronary arteriography. When analysis was carried out from a cine loop display a new wall motion abnormality had a sensitivity of 12% and a specificity of 100% for coronary artery disease. From stroke volume images the sensitivity was 35% and the specificity 87%. It is concluded that cold pressor induced wall motion changes are too insensitive to be a useful method of screening for coronary artery disease.

Adult↗
PubMed1984

Improved lesion detection with dimethyl-amino-diphosphonate: a report of two cases.

In two patients with metastatic disease more lesions were detected on scintigraphs obtained with the 'low uptake' bone-scanning agent dimethyl-amino-diphosphonate. The results in these two patients provide practical support for the suggestion that bone-scanning agents with low uptake in normal bone, but high tumour-to-normal bone ratios, will allow better delineation of focal bone abnormalities.

Aged↗
PubMed1984

The combined role of atheroma, cholesterol, platelets, the endothelium and fibrin in heart attacks and strokes.

In 1920 the typical American diet was rich in cholesterol and fat, especially saturated animal fat, with one-third the polyunsaturated vegetable fat as now; yet in that year, death from myocardial infarction (MI) in the United States was so rare that it had no name or medical recognition. In 1960, when MI deaths in the United States had soared to an alarming rate of 600,000, orthodox medicine concluded that cholesterol and saturated animal fat in food caused elevated cholesterol in blood, which caused cholesterol in atheroma, which in turn caused death from MI and strokes. It is suggested that human atheroma is made up mostly of fibers of either collagen or fibrin, smooth-muscle cells or dead smooth-muscle cells, that it contains but little cholesterol, and that it is present in both men and women and in populations having little or no MI as well as in those where MI is the greatest cause of death. It is suggested that MI is largely caused by coronary blood clots formed at the site of a break in the coronary artery endothelium; that the introduction of a new, unnatural dietary fatty acid--trans-trans linoleic acid--in margarine and refined vegetable oils in the 1920s, by inducing a deficiency of beneficial prostaglandin E1 (PGE1) while greatly increasing harmful thromboxane A2 (TXA2), caused vasoconstriction while the clumping of platelets was greatly increased, giving rise to the coronary blood clots that either cause or are part of the fatal process of MI. It is suggested that in fostering the increase of dietary trans-trans linoleic acid in polyunsaturated vegetable fats at the expense of saturated animal fat, orthodox medicine is fostering a principle cause of MI as the cure.

Animals↗
PubMed1984

Do we get too much iron?

Iron in hemoglobin of 14 gm/100 ml, which is considered normal, may predispose to malignancies and to rheumatoid, heart, bacterial and other infective diseases. Conversely, a mild state of iron-deficiency anemia as presented by hemoglobin of 10 gm/100 ml may be an affordable price for protection from these disease states. The harm due to too much iron is discussed.

Arthritis, Rheumatoid↗
PubMed1984

Do we get too much iron?

Iron in hemoglobin of 14 gm/100 ml, which is considered normal, may predispose to malignancies and to rheumatoid, heart, bacterial and other infective diseases. Conversely, a mild state of iron-deficiency anemia as presented by hemoglobin of 10 gm/100 ml may be an affordable price for protection from these disease states. The harm due to too much iron is discussed.

Arthritis, Rheumatoid↗
PubMed1984

Defective splenic reticuloendothelial function in idiopathic membranous nephropathy.

We studied splenic macrophage reticuloendothelial function in 18 patients with idiopathic membranous nephropathy and eight patients with mesangio-capillary glomerulonephritis by measuring the clearance from the circulation of technetium labelled, autologous, antibody coated erythrocytes (IgG cells) or heat damaged erythrocytes (HDE). Nine of 15 rhesus-D positive patients with membranous nephropathy had delayed clearance of the IgG cells and the defect did not correlate with disease activity. Circulating immune complexes were not detected in any of the patients with membranous nephropathy. The defect in clearance of the IgG cells in the membranous patients was associated with the presence of HLA-B8 and DR3. In the mesangio-capillary glomerulonephritis patients, the clearance rates of the IgG cells were fast-normal in six and enhanced in two, and correlated with the clearance of HDE. The clearance rates of the cells in this group correlated with the degree of hypocomplementaemia but not with the disease activity nor HLA haplotype.

Adult↗