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Biomedical subjects

B J Ward

Publications and source records attributed to B J Ward.

69 records · Page 4Linked to original sources
PubMed1985

Effect of dicarboxylic acids on Harding-Passey and Cloudman S91 melanoma cells in tissue culture.

Clinically, dicarboxylic acids have a cytotoxic effect on the abnormally hyperactive and malignant epidermal melanocyte, and diacids from C8 to C13 have been shown to inhibit mitochondrial oxidoreductases. Here, their effect on the growth kinetics and ultrastructure of murine melanoma cells in culture is examined. Cultures of Harding-Passey and Cloudman S91 melanoma cells were exposed to single doses of the disodium salts of C12, C9, and C6 (which does not significantly inhibit mitochondrial enzymes) dicarboxylic acids at concentrations of 10(-3) M to 10(-1) M. With C12 and C9, viability and cell proliferation over 3 days were significantly affected by concentrations greater than 10(-2) M. With exposure to C6 at 10(-1) M and to medium to which NaCl was added to produce equal osmolarity, the effect was much less. Electron microscopy of cells exposed to C9 at 10(-1) M for 1 h and 6 h revealed massive swelling of mitochondria with destruction of cristae, but plasma and nuclear membranes and membranes of endoplasmic reticulum were intact. Similar damage was not seen with C6 at 10(-1) M nor with equiosomolar NaCl. The results confirm (1) the cytotoxicity of dicarboxylic acids for malignant melanocytes, and (2) that the mitochondrion is a prime target for their action.

Adipates↗
PubMed1985

Ultrastructural observations on the effect of azelaic acid on normal human melanocytes and a human melanoma cell line in tissue culture.

Azelaic acid has been shown clinically to have a cytotoxic effect on the abnormally active and malignant human melanocyte, but it has no apparent effect upon normal melanocytes. This difference in reactivity between normal and abnormal cells in vivo is further examined here in vitro. The disodium salt of azelaic acid (C(9)2Na) was added to pure and mixed cultures of normal human melanocytes and to cultured human melanoma cells, at 10(-3) M, 10(-2) M, 5 X 10(-2) M, and 10(-1) M for 1 and 6 h. Control cultures and cultures exposed to the same concentrations of the disodium salt of adipic acid (C(6)2Na) were also examined. No damage to cells of any line was observed with diacids at 10(-3) M or 10(-2) M up to 6 h. At 5 X 10(-2) M some mitochondria of melanoma cells appeared swollen. With C(6)2Na at 10(-1) M for I and 6 h, minimal swelling of mitochondria was observed in some cells of all lines. Pure normal melanocytes and melanocytes of mixed cultures exhibited greater swelling of mitochondria with 10(-1) M C(9)2Na at 1 and 6 h, but the mitochondria of the malignant melanocytes were massively swollen with destruction of cristae. Plasma and nuclear membranes and membranes of rough endoplasmic reticulum were intact, but Golgi membranes exhibited vesiculation. These results provide further evidence that azelaic acid damages the human malignant melanocyte and that one of its targets is the mitochondrion. Damage to normal melanocytes, found here, may be due to the fact that, in culture, they are more active than in intact epidermis.

Cell Line↗
PubMed1984

Analytical, ultrastructural, autoradiographic and biochemical studies on [3H]dicarboxylic acid added to cultures of melanoma cells.

Lentigo maligna and malignant melanoma can be treated by dicarboxylic acids (C9 and C12), which are competitive inhibitors of tyrosinase. We therefore studied the intracellular location and possible sites of action of dodecanedioic acid (C12) in murine melanoma cells, using EM autoradiography and biochemical analysis of lipid extracts by HPLC. Significant levels of radioactivity were found in the mitochondria and in the nuclei but not in association with membranes of rough endoplasmic reticulum, Golgi-associated endoplasmic reticulum, or Golgi apparatus, and not in coated vesicles or melanosomes. Biochemical analysis revealed that the diacid underwent beta-oxidation, which occurs only in mitochondria. The results suggest that the toxicity of dicarboxylic acids in melanoma cells is not related to anti-tyrosinase activity but may be due to interference with oxidoreductase enzymes in the mitochondria and possibly to inhibition of DNA synthesis in the nucleus.

Animals↗
PubMed1980

Transplantation of the gonads of hypogonadal (hpg) mice.

Testes from hypogonadal (hpg) mice transplanted under the tunica albuginea of the testes of normal mice displayed full spermatogenic activity after 84 days. When ovaries of hpg mice were transplanted to the periovarian capsule of ovariectomized normal females ripe follicles and corpora lutea developed. Although small remnants of normal ovary were found after this operation, the fact that 5 out of 11 normal females bearing transplanted ovaries and mating with heterozygous males raised litters containing hpg mice shows that the ovary of the mutant is capable of producing ova which can be fertilized.

Animals↗
PubMed1980

Transport of fatty acids in the heart.

Fatty acids are taken up by the myocardium in the unesterified form, either directly from the unbound pool of free fatty acids in the plasma or following release from plasma triglycerides by lipoprotein lipase. They pass extremely rapidly into the cardiac cells, where their distribution is determined by a number of physical and biochemical factors. For the intracellular spaces these factors are essentially physical and depend on gradients of concentration of unbound fatty acids and on the concentration and affinity of protein binding sites. In the cytoplasm of the myocardial cell, myoglobin seems to play a specific carrier role. Passage of fatty acids across cell membranes depends on their chemical forms and, largely, on the degree of solubility of these forms in the lipid layer of the membranes. In addition, there may be specific transport systems, such as is mediated by carnitine in the inner mitochondrial membrane. Finally, the mass movement on fatty acids through the cells depends on the rate at which they are removed by oxidation or esterification. Under normal conditions, these various factors lead to a rapid movement of fatty acids into the mitochondria where they are oxidised and a more gradual esterification into complex lipids.

Animals↗
PubMed1979

The incorporation and distribution of 3H oleic acid in the isolated perfused guinea-pig heart: a biochemical and EM autoradiographic study.

The incorporation of 3H oleic acid into tissue lipids of guinea pig heart was studied after 15, 30, 60 or 120 sec perfusion using EM autoradiography with 'hypothetical grain' analysis and lipid analysis by thin-layer chromatography. Radioactivity in triacylglycerol and phospholipid increased and in free fatty acid decreased with time. This corresponded to an increase in radioactivity associated with lipid droplets in the autoradiographs. High levels of radioactivity were found associated with the mitochondria after only 15 sec. The movement of fatty acids is interpreted in terms of transport mechanisms, concentration gradients and bound and unbound molecules.

Animals↗
PubMed1976

Lipid losses during processing of cardiac muscle for electron microscopy.

The lipid retaining properties of several methods of processing tissue for electron microscopy (EM) have been assessed quantitatively. Guinea-pig hearts were perfused in vitro at 37 degrees C with 3H-oleic acid bound to albumin. The hearts were fixed by perfusion with 4% glutaraldehyde in 0-1 M cacodylate buffer. Pieces of left ventricle and interventricular septum were removed, weighed and processed for EM. The fluids used at each stage of processing were monitored for loss of radioactive lipid by scintillation counting. Lipids were extracted from the processed tissue immediately before the embedding stage using a mixture of chloroform:methanol (2:1 v/v). Counts from processed tissue were compared with counts from tissue extracted directly after perfusion fixation in order to monitor subsequent losses during processing. A modified version of Epon processing, omitting 100% ethanol, acetone or propylene oxide, gave a lipid retention of only 20-6%. The addition of paraphenylenediamine to the procedure did not improve the retention although this has been shown to be a useful stain for intracellular lipid. Water soluble Durcupan which does not involve ethanol or acetone dehydration has an average retention of 63% with 100% recovery while the lesser known polymer GACH, a mixture of glutaraldehyde and carbohydrazide used both for dehydration and embedding showed a lipid retention of 82% of the counts recovered although recovery was only 69%. An attempt was made to determine which classes of lipids were present in the tissue after perfusion fixation using thin layer chromatography. It was found that the presence of any of the processing fluids affected the polarity of the lipids and their rates of migration on thin layer plates.

Animals↗
PubMed1975

A freeze-fracture study of the tegumental membrane of Schistosoma mansoni (Platyhelminthes:Trematoda).

Two fracture faces in each half of the freeze-fractured tegumental membrane of adult Schistosoma mansoni indicate the presence of two trilaminate membranes. This result is compatible with the heptalaminate appearance of the tegumental membrane in ultrathin sections. Intramembranous particles are located mainly in the outermost leaflet of the outer membrane and in the cytoplasmic leaflet of the inner membrane. The tegumental membrane of the cercaria (infective larva) has a single fracture plane, which conforms with its trilaminate appearance in sections. Intramembranous particles are extremely numerous and are almost all located in the cytoplasmic leaflet.

Animals↗
PubMedDate not supplied

Microvascular permeability of the isolated rat heart to various solutes in well-oxygenated and hypoxic conditions.

The aim of this study was to investigate the effect of a moderate degree of hypoxia on coronary vascular permeability to various lipophobic solutes. Using the multiple indicator dilution method the permeability-surface area (PS) products were determined for 125I-albumin, 125I-insulin and 57Co-cyanocobalamin in perfused rat hearts (flow approximately 10 ml.min-1.g-1) either with well-oxygenated (pO2 approximately 96 kPa) or hypoxic (pO2 approximately 45 kPa) solutions. The PS products for albumin, insulin and cyanocobalamin during the well-oxygenated equilibration period were 0.20 +/- 0.03, 0.29 +/- 0.06 and 2.0 +/- 0.3 ml.min-1.g-1 (mean +/- SE), respectively, relative to 131I-gamma-globulin. The PS products for these solutes 15 min after the induction of hypoxia were 1.3 +/- 0.3, 0.8 +/- 0.1 (p < 0.05) and 2.1 +/- 0.2 (p < 0.05), respectively. In hearts perfused with well-oxygenated solution for 75 min, the PS products for these solutes remained stable throughout the period of the study. Electron-microscopic examination of hypoxic tissues showed the presence of endothelial gaps of approximately 1 micron which were underlined by an intact basal lamina. We conclude that a moderate degree of hypoxia produces a large increase in permeability of albumin and insulin but has no effect on the PS products for cyanocobalamin and that the endothelial gaps are the likely mechanism of the observed increase in permeability.

Animals↗
PubMedDate not supplied

Increasing referral of at-risk travelers to travel health clinics: evaluation of a health promotion intervention targeted to travel agents.

BACKGROUND: Increases in travel-related illness require new partnerships to ensure travelers are prepared for health risks abroad. The travel agent is one such partner and efforts to encourage travel agents to refer at-risk travelers to travel health clinics may help in reducing travel-attributable morbidity. METHODS: A health promotion intervention encouraging travel agents to refer at-risk travelers to travel health clinics was evaluated. Information on the knowledge, attitudes, and behaviors of travel agents before and after the intervention was compared using two self-administered questionnaires. The Wilcoxon signed rank test was used to compare the mean difference in overall scores to evaluate the overall impact of the intervention and also subscores for each of the behavioral construct groupings (attitudes, barriers, intent, and subjective norms). Multiple regression techniques were used to evaluate which travel agent characteristics were independently associated with a stronger effect of the intervention. RESULTS: A small improvement in travel agents overall attitudes and beliefs (p =.03) was found, in particular their intention to refer (p =.01). Sixty-five percent of travel agents self-reported an increase in referral behavior; owners or managers of the agency were significantly more likely to do so than other travel agents (OR = 7.25; 95% CI: 1.64 32.06). Older travel agents, those that worked longer hours and those with some past referral experience, had significantly higher post-intervention scores. CONCLUSIONS: Travel agents can be willing partners in referral, and agencies should be encouraged to develop specific referral policies. Future research may be directed toward investigating the role of health education in certification curricula, the effectiveness of different types of health promotion interventions, including Internet-facilitated interventions, and the direct impact that such interventions would have on travelers attending travel health clinics.

Adult↗