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Biomedical subjects

M Lombard

Publications and source records attributed to M Lombard.

At least 55 records · Page 3Linked to original sources
PubMed1996

Expression of the transferrin receptor in human anterior pituitary adenomas is confined to gonadotrophinomas.

OBJECTIVE: The human pituitary gland is affected selectively by conditions associated with iron deposition, but the mechanisms for this are unknown. In this study we have determined whether the transferrin receptor, which mediates iron uptake by cells, could be detected immunocytochemically in human pituitary adenomas in vitro. PATIENTS: Data were derived from 35 patients undergoing transsphenoidal surgery and included 13 with clinically non-functioning adenomas, 15 with acromegaly, 4 prolactinomas, 2 patients with Cushing's disease and one patient with Nelson's syndrome. MEASUREMENTS: Transferrin receptor immunopositivity was determined for each adenoma in dispersed cell culture using a specific monoclonal antibody. RESULTS: Eight of 13 clinically functionless adenomas showed immunopositive transferrin receptor expression, whilst adenomas from 15 patients with acromegaly, 4 prolactinomas, 2 Cushing's syndrome and one patient with Nelson's syndrome were negative. The eight transferrin receptor positive tumours were gonadotrophinomas and accounted for eight of the nine tumours which secreted and immunostained for FSH; all eight also secreted and immunostained for LH. CONCLUSIONS: These findings may reflect a special requirement for iron by gonadotrophin secreting cells in comparison to other pituitary cell types and this could underlie the reasons why in the normal pituitary these cells are especially susceptible to malfunction in iron overload syndromes such as genetic haemochromatosis and beta-thalassaemia.

Adenoma↗
PubMed1996

Comparative RB1 gene mapping in Homo sapiens, Pithecia pithecia, Macaca sylvana, and Cercopithecus aethiops tantalus.

The chromosomal localization of the gene for retinoblastoma (RB1), which has been mapped to band 13q14 in man, was studied by in situ hybridization on metaphase chromosomes of selected primates, including Pithecia pithecia, Macaca sylvana, and Cercopithecus aethiops tantalus. The results allowed us to determine the position of the bands homologous to human chromosome band 13q14 in these species. Hybridization analysis corroborated the results of previous studies that defined the chromosome homologous to human chromosome 13 (HSA 13) in these species. By comparing RB1 localizations and banding patterns, it is shown that the rearrangement separating HSA 13 from its homologous chromosome in Cercopithecidae is not a pericentric inversion, as suggested by earlier studies. Since the banding pattern and RB1 localization are not changed, the modification of the centromeric index is explained by a centromeric shift or by two inversions, one pericentric and one paracentric.

Animals↗
PubMed1996

Field use of a vaccinia-rabies recombinant vaccine for the control of sylvatic rabies in Europe and North America.

During recent years, most research on the control of sylvatic rabies has concentrated on developing methods of oral vaccination of wild rabies vectors. To improve both the safety and the stability of the vaccine used, a recombinant vaccinia virus, which expresses the immunising glycoprotein of rabies virus (VRG), has been developed and tested extensively in the laboratory as well as in the field. From 1989 to 1995, approximately 8.5 million VRG vaccine doses were dispersed in Western Europe to vaccinate red foxes (Vulpes vulpes), and in the United States of America (USA) to vaccinate raccoons (Procyon lotor) and coyotes (Canis latrans). In Europe, the use of VRG has led to the elimination of sylvatic rabies from large areas of land, which have consequently been freed from the need for vaccination. Nevertheless, despite very good examples of cross-border cooperation, reinfections have occurred in some regions, due to the difficulty of co-ordinating vaccination plans among neighbouring countries. In the USA, preliminary data from field trails indicate a significant reduction in the incidence of rabies in vaccinated areas.

Animals↗
PubMed1994

Further studies on the efficacy of an inactivated African horse sickness serotype 4 vaccine.

The immunity induced by two inoculations of a commercial inactivated African horse sickness (AHS) serotype 4 (AHSV-4) vaccine was studied. No adverse reaction was observed in five horses following vaccination. Following challenge-inoculation, no clinical signs attributable to AHS, no viraemia indicating infection, and no anamnestic response was observed in the vaccinated ponies. Two control ponies developed clinical signs typical of AHS, high levels of viraemia, and died 7 and 8 days postchallenge-inoculation. The quality of immunity induced by the two-dose regimen was compared with a one-dose regimen from a previous study; in the one-dose study following challenge-inoculation, six of nine ponies were protected from clinical signs of AHS, seven of the nine vaccinated ponies developed an anamnestic response, and one pony had a viraemia about 10(3) 50% mouse lethal dose of AHSV-4 per ml of blood for 3 days following challenge-inoculation. The utility of an efficacious inactivated AHS vaccine in the control and eradication of AHS from a non-endemic area is discussed. The lack of viraemia following vaccination with an inactivated vaccine and the prevention of vector infection by animals exposed to field virus are important in the eradication of AHS.

African Horse Sickness↗
PubMed1993

Tissue iron loading and histopathological changes in hypotransferrinaemic mice.

Tissue iron loading in hypotransferrinaemic (hpx/hpx) mice was investigated as a model for genetic (primary) haemochromatosis. Iron loading of liver preceded that in the pancreas and heart. One-year-old hpx/hpx mice showed iron staining in exocrine pancreas, liver parenchymal cells, and cardiac and intestinal smooth muscle cells. Iron-loaded macrophages were observed in all these tissues. Islets of Langerhans, biliary epithelial cells, and spleen were iron-free. The pancreas was fibrotic with massive macrophage infiltration and loss of secretory epithelium. Liver showed evidence of chronic inflammatory infiltration with increased collagen fibres in the parenchymal region but no cirrhosis. Serum aspartate aminotransferase activity and plasma glucose were increased in hpx/hpx compared with wild-type mice. Heavy iron loading with haemosiderin deposition in the liver could be demonstrated in hpx/hpx mice from 6 weeks of age. Heterozygous hypotransferrinaemic mice showed minor increases in liver iron stores at 6-12 weeks, but not at 1 year of age. Serum ferritin levels in heterozygous mice were also increased at 6-8 weeks of age. It was concluded that 1-year-old hpx/hpx mice showed evidence of liver and pancreatic damage secondary to tissue iron overload. The iron loading pattern and tissue damage showed some features which were distinct from those observed in haemochromatosis.

Animals↗
PubMed1993

Cyclosporin A treatment in primary biliary cirrhosis: results of a long-term placebo controlled trial.

BACKGROUND: Effective treatment for primary biliary cirrhosis (PBC) resulting in slower progression and improved survival remains elusive. Cyclosporin A (CyA), which has been so effective in preventing human allograft rejection, has shown promise in small numbers of patients in early studies. METHODS: Three hundred forty-nine patients with PBC were randomized to receive CyA, 3 mg.kg-1.day-1, or placebo in a multicenter study with follow-up for 6 years. The end point was death or liver transplantation. RESULTS: Cox multivariate analysis showed time from entry to death or transplantation was significantly prolonged (by up to 50%) in the CyA-treated group. Liver-related mortality was also significantly lower. However, a univariate analysis of survival showed no statistical differences between the two groups. Biochemical liver indices deteriorated more slowly in the CyA-treated group, but serum creatinine concentration was elevated > 150 mumol/L in 9%, necessitating permanent discontinuation in half of these. A reduction in the dose of CyA was required in 11% because of hypertension. CONCLUSIONS: CyA has some therapeutic potential in primary biliary cirrhosis, providing blood pressure and renal function are closely monitored.

Adult↗
PubMed1993

Aneuploidy in human lymphocytes: an extensive study of eight individuals of various ages.

Data on aneuploidy from a prospective study on a large number of lymphocyte metaphases (over 1000 in 72-h and 100 in 48-h cultures) per individual from eight healthy donors of various ages are reported. Chromosome losses were dependent on culture time, being significantly more frequent in 72-h than in 48-h cultures. All donors exhibited various degrees of aneuploidy which increased with age in women. This increase resulted essentially from X chromosome losses, as previously reported. Although the rate of aneuploidy limited to autosomes was similar in newborns and in adults, the distributions of the missing autosomes were different. In the two newborns studied, autosome aneuploidy was random. In the adults, a significant inverse correlation with autosome lengths was observed. The inverse correlation between chromosome lengths and losses may be explained by selective pressure against monosomic cells in the adults.

Adult↗
PubMed1993

Studies of human zinc kinetics using the stable isotope 70Zn.

1. The short-term (120 min) kinetics of Zn turnover has been studied in control subjects and patients with alcoholic liver disease after intravenous injection of 0.5 mg of 96.5% enriched 70ZnCl2. 2. The 70Zn enrichment of plasma was found closely to obey two-compartment kinetics and the derived two-component decay equation has been used to calculate the size and turnover of the initial two rapidly exchanging pools of body Zn. 3. In normal subjects isotopic Zn appears initially to equilibrate with the whole of the plasma Zn which comprises the first metabolic compartment, pool a. This has a size of 0.72 +/- 0.1 mumol/kg. 70Zn equilibration then occurs with a second compartment, pool b, consistent with a rapidly exchanging liver Zn pool of size 3.60 +/- 0.93 mumol/kg. The fractional turnover rate of pool b was found to be fivefold slower than that of pool a. 4. In the alcoholic group an expansion of pool a was observed (1.63 +/- 0.39 mumol/kg), but the size of the second pool was not significantly different from that of control subjects (5.55 +/- 1.0 mumol/kg), although its fractional turnover was significantly increased (Kab: control subjects, 0.018 +/- 0.002 min-1, alcoholic patients, 0.031 +/- 0.006 min-1). 5. These data therefore demonstrate that kinetic studies using stable isotopes of Zn can provide novel information on exchangeable Zn pools in man, but provide no support for the possibility of an underlying Zn depletion in patients with alcoholic liver disease.

Adult↗
PubMed1992

Constitutional balanced translocations in patients with solid tumors.

In a sample of 329 patients with a solid tumor (colon and breast adenocarcinoma, cervical carcinoma, and meningioma), four balanced constitutional translocations were observed. Two were t(13q14q), and two were reciprocal translocations. Comparison with surveys of newborns showed a significant excess of translocations in our sample.

Adenocarcinoma↗
PubMed1992

Persistent iron overload 4 years after inadvertent transplantation of a haemochromatotic liver in a patient with primary biliary cirrhosis.

An iron-loaded liver from a 20-year-old man with occult haemochromatosis was inadvertently transplanted into a 64-year-old lady with primary biliary cirrhosis. Increased hepatic iron storage was observed in biopsy specimens undertaken at 18, 30 and 36 months after transplantation. Serum iron levels and transferrin iron saturation increased and remained elevated 4 years after surgery. Ferritin levels were also consistently increased. Iron absorption test, performed at 4 years after transplant, was increased at 38%. Our data suggest that an intrahepatic defect in haemochromatosis cannot be excluded, and casts some doubt on the assertion that a precirrhotic haemochromatotic liver can be transplanted without sequelae.

Adult↗
PubMed1992

Management of common bile duct stones with a biliary endoprosthesis. Report on 40 cases.

Endoscopic placement of a biliary endoprosthesis has been proposed for the management of choledocholithiasis when stone extraction is difficult or considered hazardous. Over a two year period this approach was used in 40 such patients. There were 24 women and 16 men with a median age of 76 years. In seven patients with severe cholangitis no attempt was made to extract the stones. Twenty three (57.5%) patients underwent a sphincterotomy and four (10%) needle knife papillotomy. The endoprosthesis insertion was considered a temporary measure in 13 (32.5%) patients and definitive treatment in 27 (67.5%). Bile duct drainage was established in all patients. Early complications occurred in six patients (15%), but were without sequelae. Late complications developed in eight (20%) of the patients and included biliary colic (four), cholangitis (three), and cholecystitis (one). Two patients (one cholangitis and one cholecystitis) died as a consequence of the complication. Only patients without a sphincterotomy developed cholangitis. A total of eight patients (20%) underwent surgery (one as an emergency) and nine a repeat endoscopic retrograde cholangio pancreatography (two as an emergency) to clear the duct. The remaining 23 patients are asymptomatic at a median of 13 months (range five to 24 months). Biliary endoprosthesis insertion for choledocholithiasis is an important alternative means of establishing drainage in selected cases, and is probably the optimum method of management for the elderly and or debilitated patients with previous cholecystectomy. Caution must be exercised, however, in patients with an in situ gall bladder.

Adult↗
PubMed1992

Assessment of the percutaneous endoscopic gastrostomy feeding tube as part of an integrated approach to enteral feeding.

The insertion of percutaneous endoscopic gastrostomy has been well documented. The possible benefits for patient nutrition and nursing practice have, however, not been assessed. We report a study of enteral feeding by percutaneous endoscopic gastrostomy in 30 patients, the majority with a persistent vegetative state. All patients had previously been fed through a nasogastric tube using manual administration and a dietitian assessed protein calorie intake. Based upon body mass index (weight/height2), midarm circumference and triceps skinfold thickness, 20 (67%) were malnourished, with 10 patients having a body mass index less than 17 (severe malnutrition); attributed to high rates of both tube displacement and feed regurgitation. Patients were observed over six to 12 months after percutaneous endoscopic gastrostomy insertion combined with overnight continuous pump feeding. All patients attained a body mass index greater than 17, and 17 (56%) of the total number achieved the normal range with no change in protein-calorie intake (pre: 2110 kcal, post: 1880 kcal). Complications of percutaneous endoscopic gastrostomy in the study group included peritonitis (one), tube site infection (two) and displacement (two); all without serious sequelae. As part of an integrated approach percutaneous endoscopic gastrostomy proved a safe and efficient method of enteral feeding and justifies wider consideration in the United Kingdom.

Adult↗
PubMed1991

Iron absorption by hypotransferrinaemic mice.

Iron absorption rates by homozygous and wild-type mice from a hypotransferrinaemic mouse colony were examined with in vivo tied-off duodenal segments and in vitro incubated duodenal fragments. Enhanced initial rates of mucosal uptake and carcass transfer by homozygotes, compared to wild-types, were observed. The changes in vivo and in in vitro uptake kinetics resemble changes seen in iron deficient or hypoxic mice, suggesting that the liver iron loading shown by homozygotes is due to a failure of the normal mechanism for regulation of iron absorption. In vivo mucosal uptake and carcass transfer of radioiron showed an inverse correlation with liver non-haem iron content in homozygous hypotransferrinaemic mice, suggesting that some degree of control of absorption, albeit at markedly reduced sensitivity, can operate in these mice. No correlation between haemoglobin level and iron absorption was observed in homozygous hypotransferrinaemic mice, suggesting that this regulator of iron absorption does not function in these mice. The precise pathogenic mechanism of the enhanced iron absorption in hypotransferrinaemia remains to be determined. Mucosal transferrin levels were found to parallel serum transferrin levels in homozygotes, heterozygotes and wild-type mice. This supports previous suggestions that mucosal transferrin is derived from plasma transferrin and that the enhancement of iron absorption, by physiological mechanisms, does not require the presence of mucosal transferrin.

Absorption↗