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Biomedical subjects

H White

Publications and source records attributed to H White.

At least 109 records · Page 6Linked to original sources
PubMed1991

Purification and some properties of the tungsten-containing carboxylic acid reductase from Clostridium formicoaceticum.

Judged by properties observed during the purification and based on the sequence of the first 25 amino acids, the enzyme from Clostridium formicoaceticum catalysing the reversible reduction of non-activated carboxylic acids to aldehydes at the expense of reduced viologens, is astonishingly different from that found by us in C. thermoaceticum. According to native and SDS gel electrophoresis the reductase is nearly homogeneous after only 26-fold purification. The specificity for various substrates and artificial electron carriers is also broad, but V of the purified aldehyde dehydrogenase activity (54 U/mg enzyme for butanal) is about 1 order of magnitude lower than that of the enzyme from C. thermoaceticum. The reductase is a dimer of two identical subunits with an Mr of 67,000 each. Increased enzyme concentrations seem to lead to higher oligomers. Per dimer 11 +/- 1 iron, 16 +/- 1 acid labile sulphur, 1.4 tungsten and after permanganate oxidation 1.6 mol pterin-6-carboxylic acid have been found.

Aldehyde Dehydrogenase↗
PubMed1991

Transposition of the greater omentum in the prevention and treatment of radiation injury.

The greater omentum provides a tissue flap that can readily be transposed for surgical reconstruction both inside and outside the abdominal cavity. To prevent radiation enteritis, an omental sling or envelope can be constructed at the end of an abdominal operation to displace small bowel from the pelvis prior to radiotherapy. The immunological and angiogenic properties of the omentum are particularly useful when reconstruction is required in a region of late radiation injury. Indications for omental transposition in this context include reinforcement of anastomoses, pelvic fistula repair, chest wall and axillary reconstruction, vascular cover, pharyngostoma, bronchopleural fistula and possibly lymphoedema.

Enteritis↗
PubMed1991

Fulminant hepatic failure after repeated exposure to isoflurane anesthesia: a case report.

A previously healthy but obese 26-yr-old woman was diagnosed as having hepatic dysfunction 17 days after the third of three consecutive exposures to isoflurane anesthesia for paranasal sinus surgery. Serum laboratory findings included elevated aminotransferases and bilirubin. Radiographical evaluations showed no evidence of extrahepatic disease. Serological studies were negative for acute viral infections, and serum copper was normal. The patient's condition deteriorated over the ensuing 17 days, with hyperreflexia, hypoglycemia and a rapid fall in serum aminotransferases with a concomitant rise in bilirubin level and prothrombin time despite maximal medical support. The liver volume as shown by computed tomography fell from 1,290 cm3 to 680 cm3 over 6 days. The patient underwent successful orthotopic liver transplantation 25 days after onset of symptoms. Histopathological examination of the resected liver showed submassive and massive necrosis, with a few foci of microvesicular steatosis and ultrastructural evidence of mitochondrial abnormalities. Although we found insufficient evidence to prove that this case was caused by isoflurane anesthesia, the clinical course and histopathological findings are similar to those in hepatic injury caused by halothane anesthesia. Therefore we report this as a possible case of fulminant hepatic failure resulting from isoflurane anesthesia.

Adult↗
PubMed1990

Evaluation of melanoma/skin cancer screening in Massachusetts. Preliminary results.

Although screening for melanoma/skin cancer is theoretically of value, few data are available to evaluate its effectiveness or the value of a visual exam by a dermatologist as a cancer screening tool. From the 2560 persons screened for melanoma/skin cancer in Massachusetts in 1986 and 1987, the authors followed the positive screenees to determine their final diagnosis. The authors obtained information on 85% of these persons, and found nine malignant melanomas, 91 non-melanoma skin cancers, 39 dysplastic nevi, and three congenital nevi. The sensitivity of the visual exam by a dermatologist was 89% to 97% and the predictive value positive was 35% to 75% for skin cancer. The authors conclude that the yield of screening is equivalent to that of other major cancer screening efforts and that the sensitivity and predictive value of the visual examination by the dermatologist is appropriate for a cancer screening tool.

Carcinoma in Situ↗
PubMed1990

Hemispheric resource limitations in comprehending ambiguous pictures.

Ambiguous pictures (Roschach inkblots) were lateralized for 100 msec vs. 200 msec to the right and left hemispheres (RH and LH) of 32 normal right-handed males who determined which of two previously presented words (an accurate or inaccurate one) better described the inkblot. Over the first 32 trials, subjects receiving each stimulus exposure duration were less accurate when the hemisphere receiving the stimulus also controlled the hand used to register a keypress response (RH-left hand and LH-right hand trials) than when hemispheric resources were shared, i.e., when one hemisphere controlled stimulus processing and the other controlled response programming. These differences were eliminated when the 32 trials were repeated.

Adult↗
PubMed1990

A study of the predominant genotypes of bovid herpesvirus 1 found in the U.K.

The genotypic classification of 84 U.K. isolates of bovid herpesvirus 1 was determined by the restriction endonuclease technique. Preliminary studies with six enzymes (EcoRI, HindIII, HpaI, BamHI, PstI and BstEII) showed that the principal genotypic variants, including the live vaccine strains used in the U.K., could be identified from the digestion patterns with just two endonucleases: HindIII and HpaI. Isolates from the 1960s were all categorised as genotype 2b. From 1977 onwards, genotype 1 has predominated in mainland Britain, with occasional type 2b isolates. Type 2b viruses were isolated from both respiratory and genital disease cases. There was no evidence of genotypes 2a or 3 in the U.K.

Animals↗
PubMed1990

Bovine spongiform encephalopathy: detection and quantitation of fibrils, fibril protein (PrP) and vacuolation in brain.

Bovine spongiform encephalopathy (BSE) is a new disease of cattle which has considerable homology with scrapie, the archetype of the transmissible spongiform encephalopathies. Abnormal brain fibrils, called scrapie associated fibrils (SAF), are specific ultrastructural markers for these diseases. Fibril detection was compared with histopathological diagnosis in the brains of 167 cattle; 157 clinically suspect BSE and 10 clinically normal. Fibrils were detected in samples of pooled brain regions of 67/144 in which vacuolar changes of BSE were confirmed, but absent in the remaining 23 brains, in which no vacuolation was found, including those from the clinically normal cattle and 13 with alternative neuropathological diagnoses. When eight defined anatomic regions from the brains of another 22 affected cows were examined, the sensitivity of fibril detection was greater than 90% for the brain stem areas. Fibril prevalence in these areas approximated to severity of vacuolar changes. When the same defined regions from four of the affected cows were assayed for fibril protein (PrP) by western blotting, the density of immuno-labelling generally correlated with the fibril prevalence. This study confirms the specificity of fibril detection for BSE, shows that the ease of fibril detection depends on anatomic region sampled and suggests an association between PrP accumulation and vacuolar changes in certain neuroanatomic areas.

Animals↗
PubMed1990

Comparison of 5-fluorouracil pharmacokinetics following intraperitoneal and intravenous administration using in vivo 19F magnetic resonance spectroscopy.

Intrahepatic pharmacokinetic studies of 5-Fluorouracil (5 FU) metabolism following intravenous and intraperitoneal administration have been undertaken in four patients using in vivo 19F nuclear magnetic resonance spectroscopy. Following intravenous administration, 5 FU decayed with "half times" ranging from 5 to 17 min. There was considerable variation of 5 FU pharmacokinetics between patients following intraperitoneal administration. Peritoneal contamination by infused 5 FU was considered to be a significant problem in one patient. A technique for providing superficial signal suppression was therefore investigated and its efficacy for excluding signal from the peritoneal space has been demonstrated. Owing to the potential for contamination from peritoneal 5 FU, the accumulation of fluoro-beta-alanine (FBAL) is a more reliable indicator of drug catabolism than the measurement of unlocalized "hepatic" 5 FU. Rapid intrahepatic catabolism of 5 FU to FBAL was demonstrated in all patients. However, there was greater pharmacokinetic variation following intraperitoneal administration than following intravenous administration. Therapeutic implications of intravenous compared with intraperitoneal administration of 5 FU are discussed.

Fluorouracil↗
PubMed1990

Isolation and reactivation of bovid herpesvirus 1 in goats.

A virus isolate, recovered from the brain of a goat which died following signs of nervous disease, was identified as BHV-1. Differentiation with the antigenically related caprine herpesvirus (BHV-6) was achieved by restriction endonuclease fingerprinting. Eighteen months after the last clinical episode, BHV-1 infection was reactivated in a seropositive goat from the same herd following dexamethasone treatment.

Animals↗
PubMed1990

Antiseptic toxicity to breast carcinoma in tissue culture: an adjuvant to conservation therapy?

Of 50 patients who had scrape cytology of the excision cavity after conservative surgery for breast carcinoma, 10 (20%) had malignant cells remaining in the cavity recognised by cytology. Of these patients, 18 had histological evidence of tumour at the resection margin, giving an accuracy of the cytology of 84%, a sensitivity of 56%, and a specificity of 100%. When assayed for cytotoxicity against a breast tumour cell line (MCF7) or human fibroblasts, chlorhexidine gluconate was the most effective of eight antiseptics or antitumour agents (100% cytotoxicity at a 1/10,000 dilution) in killing breast tumour cells and had 70% toxicity to human fibroblasts at the same dilution. Hydrogen peroxide appeared to be the most useful agent overall with 94% cytotoxicity to breast tumour cells with only a 12% cytotoxicity to human fibroblasts at a dilution of 1/1,000,000. We suggest that free malignant cells left in the cavity after conservative surgery for breast cancer may be a cause of local recurrence. They can be recognised by scrape cytology at operation and the topical use of antiseptics as cytotoxic agents may be beneficial and warrants further investigation.

Adult↗