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Biomedical subjects

G M Lord

Publications and source records attributed to G M Lord.

11 recordsLinked to original sources
PubMed2000

Starvation, leptin and epithelial cell proliferation in the gastrointestinal tract of the mouse.

BACKGROUND/AIMS: Leptin, the ob/ob gene product, is a recently discovered peptide hormone, secreted by adipocytes, which can act as a satiety factor to regulate food intake. Its levels thus will be related to the presence of food in the lumen of the gut, and food intake is one of the most potent stimuli for intestinal epithelial cell proliferation. Leptin has a variety of other actions and the aim of this study was to see if one of these was to stimulate mucosal growth. METHODS: Three groups of mice were fed ad libitum, starved for 48 h or starved for 48 h and given twice-daily intraperitoneal injections of recombinant leptin (1 microg/g). RESULTS: Starvation led to a 20% decrease in body weight and a similar decrease in the weights of the intestines. Starvation also markedly inhibited intestinal epithelial cell proliferation. Leptin had little effect on the small intestine and did not stimulate proliferation. However, in the hind gut it was associated with small but significant decreases in caecal weight, distal colon mitotic counts (p = 0.036) and in colonic crypt area (approximately 20%, p<0.001). CONCLUSION: Leptin did not stimulate intestinal cell proliferation, however it did have a paradoxical inhibitory action on the caecum and colon.

Animals↗
PubMed2000

Increased leptin levels in serum and peritoneal fluid of patients with pelvic endometriosis.

Pelvic endometriosis is an immune-related chronic inflammatory disease, characterized by ectopic implants of endometrium in the peritoneal cavity and associated with increased secretion of proinflammatory cytokines and neoangiogenesis. Leptin, the adipocyte-derived hormone, has been shown to have a role in food intake, basal metabolism, and reproductive function. Leptin levels are dynamically regulated, being elevated by inflammatory mediators and reduced by starvation. Leptin itself can influence the proinflammatory immune responses of CD4+ T lymphocytes, and reports have also shown this hormone to be an angiogenic factor in vitro and in vivo. We investigated whether leptin concentrations in serum and peritoneal fluid (PF) differed between 13 patients with different stages of endometriosis and 15 age- and body mass index-matched controls. We found a statistically significant (P < 0.05) increase in leptin levels in serum (30.3 +/- 14.8 ng/mL) and PF (35.9 +/- 17.4 ng/mL) of patients with endometriosis, compared with our control population (serum, 15.6 +/- 8.4; PF, 17.5 +/- 7.2 ng/mL). Regression equations, relating leptin to body mass index, were also significantly different in endometriosis patients, compared with controls. Higher levels of leptin were observed in the earlier stages of endometriosis than advanced-stage disease. These data suggest that the proinflammatory and neoangiogenic actions of leptin may contribute to the pathogenesis of endometriosis.

Adult↗
PubMed1999

Nephropathy caused by Chinese herbs in the UK.

The use of Chinese herbal remedies is increasing in the UK. We report the presence of a nephrotoxic compound in herb samples, which led to end-stage renal failure in two patients. We suggest that use of these products is regulated more tightly.

Aristolochic Acids↗
PubMed1999

Leptin protects mice from starvation-induced lymphoid atrophy and increases thymic cellularity in ob/ob mice.

Thymic atrophy is a prominent feature of malnutrition. Forty-eight hours' starvation of normal mice reduced the total thymocyte count to 13% of that observed in freely fed controls, predominantly because of a diminution in the cortical CD4(+)CD8(+) thymocyte subpopulation. Prevention of the fasting-induced fall in the level of the adipocyte-derived hormone leptin by administering exogenous recombinant leptin protected mice from these starvation-induced thymic changes. The ob/ob mouse, which is unable to produce functional leptin because of a mutation in the obese gene, has impaired cellular immunity together with a marked reduction in the size and cellularity of the thymus. We found that ob/ob mice had a high level of thymocyte apoptosis resulting in a ratio of CD4(+)CD8(+) (cortical) to CD4(-)CD8(-) (precursor) thymocytes that was 4-fold lower than that observed in wild-type mice. Peripheral administration of recombinant leptin to ob/ob mice reduced thymocyte apoptosis and substantially increased both thymic cellularity and the CD4(+)CD8(+)/CD4(-)CD8(-) ratio. In contrast, a comparable weight loss in pair-fed PBS-treated ob/ob mice had no impact on thymocyte number. In vitro, leptin protected thymocytes from dexamethasone-induced apoptosis. These data indicate that reduced circulating leptin concentrations are pivotal in the pathogenesis of starvation-induced lymphoid atrophy.

Animals↗
PubMed1998

Leptin modulates the T-cell immune response and reverses starvation-induced immunosuppression.

Nutritional deprivation suppresses immune function. The cloning of the obese gene and identification of its protein product leptin has provided fundamental insight into the hypothalamic regulation of body weight. Circulating levels of this adipocyte-derived hormone are proportional to fat mass but maybe lowered rapidly by fasting or increased by inflammatory mediators. The impaired T-cell immunity of mice now known to be defective in leptin (ob/ob) or its receptor (db/db), has never been explained. Impaired cell-mediated immunity and reduced levels of leptin are both features of low body weight in humans. Indeed, malnutrition predisposes to death from infectious diseases. We report here that leptin has a specific effect on T-lymphocyte responses, differentially regulating the proliferation of naive and memory T cells. Leptin increased Th1 and suppressed Th2 cytokine production. Administration of leptin to mice reversed the immunosuppressive effects of acute starvation. Our findings suggest a new role for leptin in linking nutritional status to cognate cellular immune function, and provide a molecular mechanism to account for the immune dysfunction observed in starvation.

Adult↗
PubMed1997

Multiple Cladosporium brain abscesses in a renal transplant patient: aggressive management improves outcome.

Infection remains one of the major complications of nonspecific immunosuppression in renal transplant patients and accounts for significant morbidity and mortality. The incidence of infectious complications has been shown to be related to the degree of immunosuppression and correlated with the total steroid dosage, use of antilymphocyte serum, and number of rejection episodes. We present the case of a patient who received a large cumulative immunosuppressive load as treatment for her original disease and for numerous rejection episodes following renal transplantation, and who later developed multiple brain abscesses. These were shown to be due to the saprophytic black fungus Cladosporium bantianum. This case emphasizes the importance of aggressively pursuing the diagnosis in immunosuppressed individuals--appropriate treatment may be instituted early and may save lives. There have been no previous cases of patients surviving this condition without neurosurgical resection of the lesions.

Adult↗
PubMed1997

Plasma immunoreactive leptin concentration in end-stage renal disease.

1. Leptin is thought to be an inhibitor of appetite. As the kidney helps clear several polypeptide hormones, plasma leptin may accumulate in end-stage renal disease. 2. Plasma immunoreactive leptin was measured in four groups of subjects: haemodialysis, continuous ambulatory peritoneal dialysis and renal transplant patients and a group of healthy controls. Leptin was also measured before and after a single dialysis session. 3. There was a strong correlation between plasma immunoreactive leptin and body mass index in all groups except female haemodialysis patients. Leptin was higher in females than in males in all groups when controlled for body mass index. Mean plasma leptin [mean (SD)] was significantly higher in all renal groups [haemodialysis, 15.1 (3.6) ng/ml; continuous ambulatory peritoneal dialysis, 25.4 (4.3) ng/ml; transplants, 11.6 (2.6) ng/ml] compared with controls [5.3 (2.3) ng/ml]. There was a significant difference in the regression equations relating leptin and body mass index (dialysis > transplants > controls), even when controlled for gender. Leptin correlated modestly with serum creatinine in non-dialysis subjects. Plasma leptin immunoreactivity was slightly reduced by haemodialysis, but post-dialysis leptin was still significantly higher than that found in controls. 4. Chromatographic characterization of the high level of leptin immunoreactivity found in haemodialysis subjects showed a single elution peak corresponding to that of the highly purified human leptin standard. 5. In conclusion, leptin is higher than expected for body mass index in end-stage renal disease. Hyperleptinaemia could contribute to the anorexia and poor nutritional status commonly seen in renal failure.

Adult↗
PubMed1993

Spontaneous spinal epidural haematoma: a cautionary tale.

Less than two hundred cases of spontaneous spinal epidural haematoma (SSEH) have been reported in the literature and theories as to its genesis are diverse. It is a serious condition, especially if there is a delay in diagnosis, as early treatment confers marked prognostic advantage. We present a case report of a 68-year-old male who was diagnosed as having a spinal epidural haematoma, followed by a discussion of the possible aetiology of this condition.

Aged↗
PubMedDate not supplied

Immunotherapy.

A forward looking conference took place at the Royal College of Physicians in June 1998. The audience, which included many scientific and clinical immunologists from both the university and pharmaceutical sector, participated knowledgeably and critically in the discussions on possible future treatments for immunologically caused diseases and on the scientific principles which may bring about further developments in immunotherapy.

Autoimmune Diseases↗