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Biomedical subjects

A Richmond

Publications and source records attributed to A Richmond.

87 records · Page 5Linked to original sources
PubMed1981

Photosynthetic and Respiratory Activity in Anacystis nidulans Adapted to Osmotic Stress.

Anacystis nidulans cultures growing photoautotrophically in a minimal medium were exposed to different concentrations of NaCl, up to 0.4 molar. Initially, a marked decrease in photosynthetic activity took place, which was in direct relation to the salt concentration and which was not associated with a change in endogenous respiratory activity. After a period of exposure to salinity, a process of adaptation became apparent, being manifested in a partial reversal of the decline in photosynthesis and a marked increase in endogenous respiration.

Journal Article↗
PubMed1980

Effect of plasma inter-alpha trypsin inhibitor and cancer-related glycoprotein EDC1 on phytohemagglutinin-induced thymidine uptake in lymphocytes.

EDC1, a glycoprotein with a molecular weight of 27,500, was purified from the urine of a leukemic patient, and a radioimmunoassay was developed to use as an immunodiagnostic tool for cancer. Previous studies showed that up to 60% of patients with disseminated neoplastic diseases excreted 100 to 500 mg of EDC1 per day. This protein was immunologically related to inter-alpha-trypsin inhibitor (IATI; M.W. 170,000), a glycoprotein normally present in plasma. EDC1, like IATI, inhibited trypsin and chymotrypsin. EDC1 and IATI have now been found to inhibit the incorporation of thymidine into DNA of normal lymphocytes transformed by phytohemagglutinin. In the presence of 1000 micrograms of EDC1 or 300 micrograms of IATI, incorporation of thymidine by cells was totally inhibited. These proteins were not cytotoxic, did not affect transport of thymidine across the membrane, formed no complex with phytohemagglutinin, and did not compete with phytohemagglutinin for its binding sites. It is proposed that EDC1 and IATI may exert this effect by inhibiting a protease required for blastogenesis.

Alpha-Globulins↗
PubMed1980

Elevated plasma and urinary guanosine 3':5'-monophosphate and increased production rate in patients with neoplastic diseases.

The plasma and 24-hr urinary levels of cyclic adenosine 3':5'-monophosphate and of cyclic guanosine 3':5'-monophosphate (cGMP) were determined for 19 healthy normal patients, 54 patients with six types of nonneoplastic diseases (cholelithiasis, peptic ulcer, coronary heart disease, hypertension, regional ileitis, and cirrhosis), and 54 patients with five types of neoplastic disease (cancers of the lung, colon, and breast, acute myelocyte leukemia, and Hodgkin's disease). The cyclic adenosine 3':5'-monophosphate levels of urine and plasma in normal subjects, in noncancer subjects, and in cancer subjects did not differ significantly. The cGMP levels in the noncancer group were similarly unchanged from those in the normal group. However, mean cGMP levels in the urine and plasma of patients with neoplastic diseases were, respectively, 2- and 3-fold greater than the normal values (p less than 0.005 for urine and p less than 0.05 for plasma). Pharmacokinetic studies with [3H]cGMP in nine healthy controls and 15 patients with neoplasia showed that the mean production rate of this nucleotide in patients with metastatic cancer was elevated when compared to normal patients, but many values fell within the normal range. In acute leukemia, the production rate was seven times normal, with four of five patients having values clearly outside the normal range. The plasma clearance rate in patients with neoplasia was not decreased when compared to that in normal patients. It is proposed that an increased production rate, rather than any change in plasma clearance, accounts for the increased levels of cGMP in the plasma and urine of some patients with neoplastic disease.

Cyclic AMP↗
PubMed1974

Leucyl-transfer ribonucleic acid synthetase in senescing tobacco leaves.

1. The activity of leucyl-tRNA synthetase obtained from tobacco leaves declined by 50% over a period of 4 days senescence induced by detachment. In addition tRNA(Leu) from senescing leaves was charged to a lesser extent than tRNA(Leu) extracted from mature leaves immediately after detachment. 2. tRNA(Leu) was charged with a synthetase preparation from either mature or senescent leaves and chromatographed on an RPC 3 column. The elution profile showed that the marked decline in specific activity of leucyl-tRNA synthetase in senescent leaves was not associated with a loss of acylation of any isoacceptor of tRNA(Leu).

Aging↗
PubMed1966

Protein and nucleic acid metabolism in fruits. I. Studies of amino acid incorporation during the climacteric rise in respiration of the avocado.

Incorporation of (14)C L-valine and (14)C L-leucine into protein of tissue slices of the avocado fruit was relatively high during the early stages of the climacteric rise, declined sharply thereafter, and was virtually absent at the peak. The incorporation of amino acids in the preclimacteric stage was markedly lower than during the early stage of the respiratory rise. By following incorporation in relation to uptake at several concentrations it was established that the results were not a reflection of endogenous dilution. Puromycin was effective as an inhibitor of incorporation but not of oxygen uptake. When respiration was at its maximum there was no protein synthesis. It was concluded, therefore, that the respiratory upsurge characteristic of the climacteric was not related directly to protein synthesis.

Amino Acids↗
PubMedDate not supplied

Sustainable, high-yielding outdoor mass cultures of Chaetoceros muelleri var. subsalsum and Isochrysis galbana in vertical plate reactors.

Continuous cultures of Chaetoceros muelleri and Isochrysis galbana were grown outdoors in flat plate-glass reactors in which light-path length (LPL) varied from 5 to 30 cm. High daily productivity (13 to 16 g cell mass per square meter of irradiated reactor surface) for long periods of time was obtained in reactors in which the optical path as well as cell density were optimized. 'Twenty centimeters was the optimal LPL, yielding the highest areal productivity of cell mass (g m(-2)d(-1)), eicosapentaenoic acid, and docosahexaenoic acid, which was identical with that previously found for polysaccharide production of Porphyridium and not far from the optimal LPL affecting maximal productivity in Nannochloropsis species. Relating the energy impinging on a given reactor surface area to the appropriate number of cells showed that the most efficient light dose per cell, obtained with the 20-cm LPL reactor, was approximately 2.5 times lower than the light dose available per cell in the 5-cm LPL reactor, in which a significant decline in areal cell density accompanied the lowest areal output of cell mass. The most effective harvesting regimen was in the range of 10% to 15% of culture volume harvested daily and replaced with fresh growth medium, resulting in a sustainable culture density of 24 x 10(6) and 28 x 10(6) cells/ml of C. muelleri and I. galbana, respectively.

Biomass↗
PubMedDate not supplied

Haemodynamic advantages of a combined inotropic/venodilator regimen over inotropic monotherapy in acute heart failure.

The haemodynamic influence of positive inotropic therapy with dobutamine, both alone and when combined with isosorbide dinitrate, was evaluated in 10 consecutive patients admitted to Coronary Care with acute left ventricular failure (pulmonary artery occluded pressure greater than 20 mm Hg) complicating myocardial infarction. Dobutamine increased systemic arterial blood pressure and heart rate without reduction in the left heart filling pressure; cardiac index (+0.9 L/min/m2; p less than 0.01) was substantially increased. Thus, consequent on these effects, dobutamine could increase myocardial oxygen requirements. The addition of intravenous isosorbide dinitrate reduced systemic arterial pressure and left heart filling pressure; the augmented cardiac index following therapy with dobutamine alone was maintained. Combined dobutamine/nitrate therapy, therefore, appeared haemodynamically superior to dobutamine monotherapy, in that it improved cardiac stroke volume at a normalised left ventricular filling pressure. These data suggest that combined dobutamine/nitrate therapy may prove useful as an adjunct to the treatment of normotensive heart failure complicating acute myocardial infarction.

Adult↗
PubMedDate not supplied

Chemokine and chemokine receptor expression in keloid and normal fibroblasts.

Keloids are benign collagenous tumors that occur during dermal wound healing in genetically predisposed individuals. The lesions are characterized by over-proliferation of fibroblasts, some leukocyte infiltration, and prolonged high rates of collagen synthesis. To determine whether leukocyte chemoattractants or chemokines are participating in this disease process, immunohistochemical staining for the CXC chemokine, MGSA/GROalpha, and its receptor, CXCR2, was performed on tissue from keloids, hypertrophic scars and normal skin. Immunoreactive MGSA/GROalpha was not observed in hypertrophic scars or normal dermis, but was present in some myofibroblasts and lymphocytes in nodular areas of the keloid samples. This staining positively correlated with the degree of inflammatory infiltrate in the lesions. Keloids, but not hypertrophic scars or normal dermis, also exhibited intensive immunoreactivity for the CXCR2 receptor in endothelial cells and inflammatory infiltrates with occasional staining of myofibroblasts. In contrast, cultured fibroblasts from either keloids or normal skin did not express detectable amounts of mRNA for MGSA/GRO or CXCR2, although interleukin-1 strongly induced MGSA/GRO mRNA in both cell types. Interleukin-1 induction of MGSA/GRO was inhibited by glucocorticoid in normal and keloid fibroblasts, and the effect was more pronounced in keloid fibroblasts. This event was not correlated with inhibition of nuclear activation of NF-kappaB, AP-1 or Sp1, and might therefore be mediated by another mechanism such as decreased mRNA stability or transcriptional repression through the glucocorticoid response element in the MGSA/GRO promoter. Data from in vitro wounding experiments with cultured normal and keloid fibroblasts indicate that there were no significant differences in MGSA/GRO or CXCR2 receptor levels between normal and keloid fibroblasts. We also show that cultured keloid fibroblasts exhibit a delayed wound healing response. We postulate that the inflammatory component is important in development of keloid lesions and chemotactic cytokines may participate in this process.

Blotting, Northern↗
PubMedDate not supplied

Childhood diabetes: dietary aspects.

Insulin-dependent diabetes mellitus in children requires a delicate balance between injected insulin and food intake, taking into account physical activity and growth.

Adolescent↗