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Biomedical subjects

L May

Publications and source records attributed to L May.

At least 37 records · Page 2Linked to original sources
PubMed1998

Quantification of penicillin-G and procaine in equine urine and plasma using high-performance liquid chromatography.

A rapid and sensitive method for the extraction and quantification of penicillin-G and procaine in horse urine and plasma samples has been successfully developed. The method involves the use of solid-phase extraction (SPE) for penicillin-G, liquid-liquid extraction (LLE) for procaine, and high-performance liquid chromatography (HPLC) for the quantification of penicillin-G and procaine. The new method described here has been successfully applied in the pharmacokinetic studies of procaine, penicillin-G and procaine-penicillin-G administrations in the horse.

Animals↗
PubMed1997

The use of play therapy in the preparation of children undergoing MR imaging.

Magnetic resonance (MR) imaging has become an important technique in the evaluation of a wide range of congenital and acquired conditions in children. The ability to image in multiple anatomic planes without the use of ionizing radiation has particular advantages. However scan times can be long, and the narrow bore and noise generated by most units make the procedure very intimidating to the young child. The use of surface coils may exacerbate this, often necessitating recourse to sedation or anaesthesia. We describe a technique involving play therapy which we have found useful in the preparation of young children for MR imaging and which has reduced the number of non-diagnostic scans and the need for sedation or anaesthesia.

Child↗
PubMed1996

A genetic map of quantitative trait loci for body weight in the mouse.

The genetic basis of body weight in the mouse was investigated by measuring frequency changes of microsatellite marker alleles in lines divergently selected for body weight from a base population of a cross between two inbred strains. In several regions of the genome, sharp peaks of frequency change at linked markers were detected, which suggested the presence of single genes of moderate effect, although in several other regions, significant frequency changes occurred over large portions of chromosomes. A method based on maximum likelihood was used to infer effects and map positions of quantitative trait loci (QTLs) based on genotype frequencies at one or more marker loci. Eleven QTLs with effects in the range 0.17-0.28 phenotypic standard deviations were detected; but under an additive model, these did not fully account for the observed selection response. Tests for the presence of more than one QTL in regions where there were large changes of marker allele frequency were mostly inconclusive.

Alleles↗
PubMed1995

Induction of interleukin 6 (IL-6) by hypoxia in vascular cells. Central role of the binding site for nuclear factor-IL-6.

The pathologic picture in ischemic tissue injury shares features with the inflammatory response, including production of proinflammatory cytokines. Hypoxia-mediated induction of interleukin-6 (IL-6), a cytokine with anti-inflammatory properties, could set in motion mechanisms limiting inflammation in ischemia. Exposure of cultured endothelial cells (ECs) to H (pO2 approximately 12-16 torr) increased transcription of IL-6, elevated levels of IL-6 mRNA, and induced elaboration of IL-6 antigen in a time-dependent manner. Exposure of mice to hypoxia increased IL-6 transcripts in the lung, and immunostaining revealed a striking increase in IL-6 antigen in pulmonary vasculature. Transfection of ECs with deletion chimeric IL-6 promoter-chloramphenicol acetyl-transferase (CAT) constructs showed hypoxia-mediated 9-11-fold induction with -1200/+13, -596/+13, and -225/+13 but no induction with -111/+13. Electrophoretic mobility shift assays (EMSAs) using -225/-111 as the labeled probe demonstrated enhanced binding activity in nuclear extracts of hypoxic ECs and lung; the appearance of the gel shift band was prevented by excess unlabeled probe (-225/-111), and hypoxia-mediated enhancement of the band was blocked by a probe corresponding to the nuclear factor (NF)-IL-6 site (-158/-145). The hypoxia-enhanced band on EMSA displayed a supershift with antibody to CCAAT-enhancer-binding protein beta (C/EBP-beta), but antibody to C/EBP-alpha or -delta was without effect. Transfection of ECs with a construct comprising thymidine kinase promoter, -225/-111 in either the 5' to 3' to 5' orientation, and the reporter CAT showed this region to be an enhancer (approximately 8-fold) under hypoxia. EMSA with the NF-IL-6 probe revealed a prominent induction of binding activity with nuclear extracts from hypoxic ECs and whole lung. Constructs with -158/-145 and the CAT reporter gene showed induction when transfected into hypoxic ECs, whereas a similar construct with the NF-IL-6 motif mutationally inactivated failed to display hypoxia-induced expression. Furthermore, the tumor necrosis factor (TNF) gene, whose product contributes to ischemic pathology and contains a putative regulatory NF-IL-6 site, demonstrated enhanced binding activity for its NF-IL-6 motif and induction of TNF mRNA based on analysis of hypoxic lung. These data indicate that hypoxia induces expression of IL-6, most likely a result of hypoxic activation at the NF-IL-6 site, and suggest that other genes with regulatory NF-IL-6 sites may also be induced by a similar mechanism.

Animals↗
PubMed1992

Laser card.

Explore the source record for details and available documents.

Diabetic Retinopathy↗
PubMed1992

Craniosynostosis--corrective surgery for a cosmetic defect.

Premature fusion of the sutures of the skull is known as craniosynostosis, and is characterised by an abnormal skull shape. Early surgery allows the brain to resume its normal shape, encouraging a more natural pattern of development. Nursing care in a craniofacial unit aims to promote maximum physical recovery and improvement, while offering psychological support and understanding to the child and family.

Aftercare↗
PubMed1991

Characterization of bromhexine and ambroxol in equine urine: effect of furosemide on identification and confirmation.

The purpose of this study was two-fold: (1) to develop a simple and sensitive screening procedure for identifying and confirming bromhexine and ambroxol and, (2) to determine the effect of furosemide on the detection of bromhexine, ambroxol, or their metabolites in urine. Female horses (450-550 kg) treated with bromhexine or ambroxol (1 g, p.o.) were used. Urine samples were collected up to 48 h post-drug administration and analysed. Blind samples were used in evaluating the sensitivity of these methods and reproducibility of the results. Bromhexine and ambroxol were extensively metabolized in the horse. These agents and their respective metabolites were identified and confirmed using thin-layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS), respectively. Hydroxy-bromhexine and desmethyl-bromhexine were major metabolites found to be unique to bromhexine-treated horses. These metabolites selectively absent from ambroxol-treated horse urine provide a chemical means to distinguish bromhexine from ambroxol administration in horses. These specific metabolites were similarly identified and confirmed in "blind" horse urine samples. The concomitant presence of furosemide (300 mg, i.v.) with bromhexine or ambroxol did not mask the presence of these agents or alter their metabolite profile. By application of the methods described in this study, bromhexine and ambroxol metabolites in horse urine can be easily identified and confirmed.

Ambroxol↗
PubMed1991

Isolation and characterization of a tomato Acid phosphatase complementary DNA associated with nematode resistance.

The tomato (Lycopersicon esculentum) acid phosphatase-1 (Apase-1(1), EC 3.1.3.2) isozyme variant, genetically linked to the root-knot nematode resistance locus (Mi) on chromosome 6, has been purified by a rapid procedure from tomato cell suspension cultures. Peptide fragments of the purified enzyme were generated from trypsin and Lys-C endoprotease digests and separated by reverse-phase high-performance liquid chromatography. Amino acid sequences derived from the purified peptide fragments represented >50% of the total amino acid content of the protein and enabled the construction of degenerate oligonucleotide probes that were used to screen a tomato cell culture complementary DNA library. Clones corresponding to full-length coding sequences for Apase-1 have been isolated and sequenced. Southern blot analysis of DNA isolated from a number of tomato cultivars shows that the Apase-1(1) gene (aps1) is present at one copy per genome and that genotypes containing the aps1(1) allele have restriction fragment length polymorphisms that distinguish them from cultivars having the aps1(+) allele. Segregation analysis demonstrates that the restriction fragment length polymorphisms are associated with the aps1 locus. Tomato Apase-1(1) is also found to have significant homology at the amino acid sequence level to a class of vegetative storage proteins characterized in soybean.

Journal Article↗
PubMed1991

Glutathione S-transferases in human liver cancer.

An immunohistochemical study of glutathione S-transferase (GST) expression in hepatocellular carcinoma and cholangiocarcinoma is described. Unlike most animal models of hepatic malignancy pi class GST was not consistently overexpressed in hepatocellular carcinoma. This tumour type either predominantly expressed alpha class GST or failed to express GST. By contrast, cholangiocarcinoma always expressed pi class GST, presumably reflecting the tissue of origin, since in human biliary epithelium pi class GST is the predominant GST. The variable expression of pi class GST which was observed in hepatocellular carcinoma may reflect transformation of hepatocytes damaged by toxins, since this GST can be induced after a chemical insult such as alcohol. As well as indicating the biochemical heterogeneity of hepatocellular carcinoma with respect to GST, this study indicates the need for further study of the nature of inherent drug resistance in these tumour types.

Adenoma, Bile Duct↗
PubMed1991

The effect of postnatal age on the adherence of enterohemorrhagic Escherichia coli to rabbit intestinal cells.

Enterohemorrhagic Escherichia coli (EHEC) are associated with hemorrhagic colitis and hemolytic uremic syndrome. These illnesses are typically seen in young children, but are rare before 6 mo of age. The cause of this age restriction is unclear. Because bacterial adherence to intestinal mucosa is considered a critical initial event in pathogenesis, we studied the ontogeny of the adherence of EHEC (O157:H7 and other serotypes) isolated from children with diarrhea, hemorrhagic colitis, or hemolytic uremic syndrome. Adherence was quantitatively determined by incubating radiolabeled bacteria with viable rabbit intestinal cells, which were prepared by treating loops of distal ileum and proximal colon with EDTA, DTT, and citrate. Cells obtained from animals of different ages were studied simultaneously. The adherence of the various EHEC strains varied significantly. A non-O157:H7 E. coli strain 43-12 bound best (35 and 32 bacteria/cell to ileal and colonic cells, respectively) with 48-60% inhibition by D-mannose and alpha-methyl mannoside (p less than 0.01) and 20-28% inhibition by L-fucose (p less than 0.05), but no significant inhibition by other carbohydrates. Analysis of variance and polynomial regression showed that postnatal age significantly affected the adherence to ileal and colonic cells. Adherence during the 1st wk of life was 13-19% of that in the adult animal; it increased gradually, reaching the adult level at about 4 wk of age. Our study shows that postnatal age affects the adherence of EHEC to intestinal cells. These findings are compatible with postnatal development of gut receptors and may be relevant to the age-related risk of EHEC disease in children.

Age Factors↗
PubMed1990

Glutathione S-transferase localization in aflatoxin B1-treated rat livers.

Overexpression of detoxication enzymes is associated with the development of drug-resistant, preneoplastic nodules in the carcinogen-treated rat liver. The most consistent marker of preneoplasia in many experimental models is increased expression of the pi-class glutathione S-transferase (GST) YfYf. We have confirmed by immunostaining that the pi-class GST is overexpressed in aflatoxin B1-induced preneoplastic nodules and liver tumours in rats. However, pi-class GST YfYf has low activity against aflatoxin B1-8,9-epoxide, and most activity against this cytotoxic and genotoxic metabolite is associated with the alpha-class GSTs YaYa, YaYc and YcYc. We have demonstrated that there is also a consistent increase in the alpha-class GSTs in this model. It seems likely that the overexpression of the Ya and Yc subunits, rather than increased levels of the pi-class GST YfYf, is responsible for the acquisition of a drug-resistant phenotype in rat liver preneoplastic nodules and tumours induced by aflatoxin B1.

Aflatoxin B1↗
PubMed1990

Glutathione S-transferases in alcoholic liver disease.

There is already evidence in alcoholic liver disease, mostly from studies of morphology and cytokeratin distribution, that hepatocytes can undergo a variety of phenotypic changes. This study reports findings of immunohistochemistry using antibodies against members of the glutathione S-transferase supergene family of detoxification enzymes. Hepatocytes in severe alcoholic liver disease coexpressed both alpha and pi class glutathione S-transferase. This coexpression has been previously described only in human fetal liver and in chemically-induced preneoplastic foci in rat liver. The use of function associated markers should provide additional information in the investigation of liver disease.

Adult↗
PubMed1990

Effect of gamma radiation on membrane fluidity of MOLT-4 nuclei.

These experiments measured the effect of gamma radiation on the nuclear envelope using doxyl-fatty acid spin-label probes. Nuclei were isolated from cultured MOLT-4 cells, a radiation-sensitive human T-cell lymphocyte. Membrane fluidity was measured from the electron paramagnetic resonance spectra of the probes. MOLT-4 cells were grown under standard conditions, and suspensions were exposed to 60Co gamma radiation at room temperature. The spectra of 5-doxylstearic acid in the nuclei were those of a strongly immobilized label. A difference in the membrane fluidity was detected in a series of experiments comparing labeled irradiated and nonirradiated nuclei. The change in fluidity was measured by comparing the changes in the order parameter, S, of the spin label in irradiated nuclei with those in control nuclei. The change in the S ratio is dependent on radiation dose, increasing with doses up to 15 Gy. The maximum change of the order parameter with time after irradiation occurs 16-20 h after radiation exposure. These observations are correlated with changes in cell viabilities.

Cell Line↗