A role for protein kinase B beta/Akt2 in insulin-stimulated GLUT4 translocation in adipocytes

Insulin stimulates glucose uptake into muscle and fat cells by promoting the translocation of glucose transporter 4 (GLUT4) to the cell surface. Phosphatidylinositide 3-kinase (PI3K) has been implicated in this process. However, the involvement of protein kinase B (PKB)/Akt, a downstream target of PI3K in regulation of GLUT4 translocation, has been controversial. Here we report that microinjection of a PKB substrate peptide or an antibody to PKB inhibited insulin-stimulated GLUT4 translocation to the plasma membrane by 66 or 56%, respectively. We further examined the activation of PKB isoforms following treatment of cells with insulin or platelet-derived growth factor (PDGF) and found that PKB beta is preferentially expressed in both rat and 3T3-L1 adipocytes, whereas PKB alpha expression is down-regulated in 3T3-L1 adipocytes. A switch in growth factor response was also observed when 3T3-L1 fibroblasts were differentiated into adipocytes. While PDGF was more efficacious than insulin in stimulating PKB phosphorylation in fibroblasts, PDGF did not stimulate PKB beta phosphorylation to any significant extent in adipocytes, as assessed by several methods. Moreover, insulin, but not PDGF, stimulated the translocation of PKB beta to the plasma membrane and high-density microsome fractions of 3T3-L1 adipocytes. These results support a role for PKB beta in insulin-stimulated glucose transport in adipocytes.

Who fails to complete tuberculosis treatment? Temporal trends and risk factors for treatment interruption in a community-based directly observed therapy programme in a rural district of South Africa

SETTING: Hlabisa Tuberculosis Programme, Hlabisa, South Africa. OBJECTIVE: To determine trends in and risk factors for interruption of tuberculosis treatment. METHODS: Data were extracted from the control programme database starting in 1991. Temporal trends in treatment interruption are described; independent risk factors for treatment interruption were determined with a multiple logistic regression model, and Kaplan-Meier survival curves for treatment interruption were constructed for patients treated in 1994-1995. RESULTS: Overall 629 of 3610 surviving patients (17%) failed to complete treatment; this proportion increased from 11% (n = 79) in 1991/1992 to 22% (n = 201) in 1996. Independent risk factors for treatment interruption were diagnosis between 1994-1996 compared with 1991-1393 (odds ratio [OR] 1.9, 95% confidence interval [CT] 1.6-2.4); human immunodeficiency virus (HIV) positivity compared with HIV negativity (OR 1.8, 95% CI 1.4-2.4); supervised by village clinic compared with community health worker (OR 1.9, 95% CI 1.4-2.6); and male versus female sex (OR 1.3, 95% CI 1.1-1.6). Few patients interrupted treatment during the first 2 weeks, and the treatment interruption rate thereafter was constant at 1% per 14 days. CONCLUSIONS: Frequency of treatment interruption from this programme has increased recently. The strongest risk factor was year of diagnosis, perhaps reflecting the impact of an increased caseload on programme performance. Ensuring adherence to therapy in communities with a high level of migration remains a challenge even within community-based directly observed therapy programmes.

Cisplatin-based therapy: A neurological and neuropsychological review

The present paper reviews research in the area of the broad-spectrum chemotherapeutic agent cisplatin (cis-diamminedichloro-platinum II) and examines the implications for clinical neuropsychology arising from the neurological disruption associated with cisplatin-based therapy. The paper begins with a brief review of cisplatin treatment in terms other than survival alone, and examines the side-effects and the potential central nervous system (CNS) dysfunction in terms of neurological symptoms and concomitant implications for neuropsychology. Two main implications for clinical neuropsychology arising from cisplatin therapy are identified. First, cisplatin therapy impacts upon the psychological well-being of the patient, particularly during and in the months following treatment. It is suggested that during this time, a primary role for neuropsychology is to focus upon the monitoring and the active enhancement of the patient's social, psychological and spiritual resources. Second, with regard to neurocognitive changes, the review suggests that (1) neurocognitive assessment may not yield stable results within 8 months following treatment and (2) while perceptual, memory, attentional and executive dysfunction may be predicted following cisplatin treatment, little systematic research has been carried out to investigate such a possibility. Future research might profitably address this issue and also specifically examine the effects of low dosage cisplatin-based therapy and the effects of recently developed neuroprotective agents. Finally, there is some evidence to suggest that women may be more susceptible to neurotoxicity during cisplatin therapy, but no gender-related cognitive effects are reported in the cisplatin literature. Future research could usefully investigate gender differences in association with cisplatin chemotherapy. Copyright (C) 2000 John Wiley & Sons, Ltd.

A comparison of three therapy methods for children with different types of developmental phonological disorder

Treatment case studies of three children whose speech was characterized by non-developmental errors are described. Three therapy methods were trialed with each child: phonological contrast; core vocabulary and PROMPT. The accuracy and intelligibility of the children's connected speech improved throughout: the course of the programme. Intervention that focused on teaching a rule about the contrastive use of phonemes was most successful for a child who consistently made non-developmental errors. Children making inconsistent errors received most benefit from the core vocabulary approach that markedly enhanced consistency of production. However, once consistency was established, one child benefited from phonological contrast therapy. While the results of the study should be interpreted with caution due to the small sample size and the cumulative effects of intervention, the findings suggest that different parts of a child's phonological and phonetic system may respond to various types of treatment approaches that target different aspects of speech production. The implication drawn is that just as no single treatment approach is appropriate for all children with disordered phonology, management of some children may involve selecting and sequencing a range of different approaches.

Placental growth hormone (GH), GH-binding protein, and insulin-like growth factor axis in normal, growth-retarded, and diabetic pregnancies: Correlations with fetal growth

We previously described significant changes in GH-binding protein (GHBP) in pathological human pregnancy. There was a substantial elevation of GHBP in cases of noninsulin-dependent diabetes mellitus and a reduction in insulin-dependent diabetes mellitus. GHBP has the potential to modulate the proportion of free placental GH (PGH) and hence the impact on the maternal GH/insulin-like growth factor I (IGF-I) axis, fetal growth, and maternal glycemic status. The present study was undertaken to investigate the relationship among glycemia, GHBP, and PGH during pregnancy and to assess the impact of GHBP on the concentration of free PGH. We have extended the analysis of specimens to include measurements of GHBP, PGH, IGF-I, IGF-II, IGF-binding protein-1 (IGFBP-1), IGFSP-2, and IGFBP-3 and have related these to maternal characteristics, fetal growth, and glycemia. The simultaneous measurement of GHBP and PGH has for the first time allowed calculation of the free component of PGH and correlation of the free component to indexes of fetal growth and other endocrine markers. PGH, free PGH, IGF-I, and IGF-II were substantially decreased in IUGR at 28-30 weeks gestation (K28) and 36-38 weeks gestation (K36). The mean concentration (+/-SEM) of total PGH increased significantly from K28 to K36 (30.0 +/- 2.2 to 50.7 +/- 6.2 ng/mL; n = 40), as did the concentration of free PGH (23.4 +/- 2.3 to 43.7 +/- 6.0 ng/mL; n = 38). The mean percentage of free PGH was significantly less in IUGR than in normal subjects (67% vs. 79%; P < 0.01). Macrosomia was associated with an increase in these parameters that did not reach statistical significance. Multiple regression analysis revealed that PGH/IGF-I and IGFBP-5 account for 40% of the variance in birth weight. IGFBP-3 showed a significant correlation with IGF-I, IGF-II, and free and total PGK at K28 and K36. Noninsulin-dependent diabetes mellitus patients had a lower mean percentage of free PGH (65%; P < 0.01), and insulin-dependent diabetics had a higher mean percentage of free PGH (87%; P < 0.01) than normal subjects. Mean postprandial glucose at K28 correlated positively with PGH and free PGH (consistent with the hyperglycemic action of GH). GHBP correlated negatively with both postprandial and fasting glucose. Although GHBP correlated negatively with PGH (r = -0.52; P

Insulin-like growth factor-I and transferrin mediate growth and survival of Chinese hamster ovary cells

The aim of this investigation was to elucidate the roles of insulin-like growth factor-I (IGF-I) and transferrin in the survival and proliferation of Chinese hamster ovary (CHO) cells upon withdrawal of serum. For this purpose, we employed DNA analysis and now cytometry to compare CHO cell lines expressing either IGF-I alone or IGF-I and transferrin. The ability of cells to cycle and the occurrence of apoptosis were monitored in these cells in serum-free medium. These results indicate that IGF-I alone is able to maintain the viability of CHO cells for an extended length of time in the absence of serum. Transferrin alone does not promote survival or proliferation. Only in the presence of both IGF-I and transferrin do cells survive and proliferate. Therefore, in attached CHO cultures, IGF-I alone does not stimulate cell proliferation but is a requirement for growth in serum-free medium in cooperation with transferrin. We report on the dual role of IGF-I as a survival factor in CHO cells and its interlocking role with transferrin to stimulate cell growth.

Recombinant human growth hormone, but not insulin-like growth factor-I, enhances central fat loss in postmenopausal women undergoing a diet and exercise program

We examined the effect of recombinant human growth hormone (rhGH) and/or recombinant human insulin-like growth factor-I (rhIGF-I) on regional fat loss in postmenopausal women undergoing a weight loss regimen of diet plus exercise. Twenty-seven women aged 59-79 years, 20-40% above ideal body weight, completed a 12-week program consisting of resistance training 2 days/week and walking 3 days/week, while consuming a diet that was 500 kcal/day less than that required for weight maintenance, Participants were randomly assigned in a double-blind fashion to receive rhGH (0.025 mg/kg BW/day: n=7), rhIGF-I (0.015 mg/kg BW/day: n=7), rhGH + rhIGF-I (n = 6), or placebo (PL: n = 7). Regional and whole body fat mass were determined by dual X-ray absorptiometry. Body fat distribution was assessed by the ratios of trunk fat-to-limb fat (TrF/LimbF) and trunk fat-to-total fat (TrF/TotF), Limb and trunk fat decreased in all groups (p < 0.01). For both ratios of fat distribution, the rhGH treated group experienced an enhanced loss of truncal compared to peripheral fat (p less than or equal to 0.01), with no significant change for those administered rhIGF-I or FL. There was no association between change in fat distribution and indices of cardiovascular disease risk as determined by serum lipid/lipoprotein levels and maximal aerobic capacity. These results suggest that administration of rhGH facilitates a decrease in central compared to peripheral fat in older women undertaking a weight loss program that combines exercise and moderate caloric restriction, although no beneficial effects are conferred to lipid/lipoprotein profiles, Further, the effect of rhGH is not enhanced by combining rhCH with rhIGF-I administration. In addition, rhIGF-I does not augment the loss of trunk fat when administered alone.

Lentiviral vector-mediated tyro sinase-related protein 2 gene transfer to dendritic cells for the therapy of melanoma

Dendritic cells (DCs) are the most potent professional antigen-presenting cells (APCs), which play a vital role in primary immune responses. Introducing genes into DCs will allow constitutive expression of the encoded proteins and thus prolong the presentation of the antigens derived therefrom. In addition, multiple and unidentified epitopes encoded by the entire tumor-associated antigen (TAA) gene may enhance T cell activation. This study demonstrated that an HIV-1-based lentiviral vector conferred efficient gene transfer to DCs. The transgene, murine tyrosinase-related protein 2 (mTRP-2), encodes a clinically relevant melanoma-associated antigen (MAA), which has been found to be a tumor rejection antigen for B16 melanoma. The transfer and proper processing of mTRP-2 in DCs, in terms of RNA transcription activity and protein expression, were verified by RT-PCR and specific antibody, respectively. Administration of mTRP-2 gene-modified DCs (DC-HR'CmT2) to C57BL/6 mice evoked strong protection against tumor challenge, for which the presence of CD4(+) and CD8(+) cells during both the priming and challenge phase was essential. In a therapy model, our results showed that four of seven mice with preestablished tumor remained tumor free for 80 days after therapeutic vaccination. Given the results shown in this study, mTRP-2 gene transfer to DCs provides a potential therapeutic strategy for the management of melanoma, especially in the early stage of the disease.

Weight reduction improves biochemistry and histology in patients with chronic hepatitis C

Hepatitis C virus (HCV) is a major cause of chronic liver disease that may progress to cirrhosis. Antiviral treatment is successful in less than 50% of patients, is costly and causes debilitating side effects. For these reasons, additional therapies to limit the progression of liver disease are urgently required. Steatosis is found in 60% of patients with HCV and is strongly associated with more severe fibrosis. Improvements in biochemical parameters may be seen with weight reduction, however the effects on liver histology have not been investigated. We propose that in patients with chronic HCV and steatosis, obesity contributes to fat in the liver, which results in increased fibrosis and progression to cirrhosis. This study investigated the effect of weight reduction on liver biochemistry and histology in patients with HCV and the success of weight maintenance after an intensive intervention. We examined the effect of a 12 week diet and exercise program where all subjects were seen weekly by the Dietician, with the goal of achieving a 0.5 kg weight loss per week. Biochemistry was monitored monthly and a liver biopsy was performed prior to and 3-6 months after the intervention period. Patients then entered a 12 month weight maintenance program with monthly dietetic review. After 12 weeks there was a mean weight loss of 5.9 ± 3.2 kg and a mean reduction in waist circumference of 9.0 ± 5.0 cm. In 16 of the 19 patients, serum ALT levels fell progressively with weight loss. Mean fasting insulin fell from 16 to 11 mmol/L (p

The VITATOPS (vitamins to prevent stroke) Trial: Rationale and design of an international, large, simple, randomised trial of homocysteine-lowering multivitamin therapy in patients with recent transient ischaemic attack or stroke

Background: Epidemiological studies suggest that raised plasma concentrations of total homocysteine (tHcy) may be a common, causal and treatable risk factor for atherothromboembolic ischaemic stroke. Although tHcy can be lowered effectively with small doses of folic acid, vitamin B-12 and vitamin B-6, it is not known whether lowering tHcy, by means of multivitamin therapy, can prevent stroke and other major atherothromboembolic vascular events. Purpose: To determine whether vitamin supplements (folic acid 2 mg, B-6 25 Mg, B-12 500 mug) reduce the risk of stroke, and other serious vascular events, in patients with recent stroke or transient ischaemic attacks of the brain or eye (TIA). Methods: An international, multi-centre, randomised, double-blind, placebo-controlled clinical trial. Results: As of November 2001, more than 1,400 patients have been randomised from 10 countries in four continents. Conclusion: VITATOPS aims to recruit and follow up 8,000 patients between 2000 and 2004, and provide a reliable estimate of the safety and effectiveness of dietary supplementation with folic acid, vitamin B-12, and vitamin B-6 in reducing recurrent serious vascular events among a wide range of patients with TIA and stroke. Copyright (C) 2002 S. Karger AG, Basel.

Weight reduction in patients with chronic HCV reduces circulating insulin levels

Steatosis occurs in >50% of patients with chronic HCV. In patients with viral genotype 3, steatosis may be a cytopathic effect of the virus. However in many patients with HCV, the pathogenesis of steatosis appears to be the same as for patients with non-alcoholic fatty liver disease (NAFLD) ie related to increased body mass index (BMI). We studied the effect of a 12 week weight reduction program on metabolic parameters in subjects with chronic HCV genotype 1 (Group 1, n = 16), genotype 3 (Group 2, n = 13) and patients with NAFLD (Group 3, n = 13). A liver biopsy was performed prior to and 3-6 months after the intervention period in 15 patients. The mean (SD) BMI of subjects in groups 1, 2 and 3 was 30.7 (4.0), 29.0 (5.2) and 33.3 (7.7), respectively. There was no significant difference in the amount of weight loss, change in waist circumference, change in ALT or reduction in steatosis between the 3 groups. Mean (SD) weight loss was 5.1 (3.7) kg. In those patients who lost weight, serum insulin (mean (SD) mU/L) changed from 17.8 (7.8) to 11.5 (4.8) (p = 0.003), 12.4 (5.0) to 8.4 (4.3) (p = 0.02), and 16.9 (7.3) to 17.8 (8.1) (p = 0.76) in Groups 1, 2 and 3, respectively. A small amount of weight loss is associated with a reduction in circulating insulin levels in patients with chronic HCV, particularly in genotype 1. In patients with NAFLD, the lack of a significant decrease in circulating insulin with weight reduction may reflect the higher initial BMI or may be due to the pathogenesis of this disorder.

Epidemiological modelling (including economic modelling) and its role in preventive drug therapy

In contrast to curative therapies, preventive therapies are administered to largely healthy individuals over long periods. The risk-benefit and cost-benefit ratios are more likely to be unfavourable, making treatment decisions difficult. Drug trials provide insufficient information for treatment decisions, as they are conducted on highly selected populations over short durations, estimate only relative benefits of treatment and offer little information on risks and costs. Epidemiological modelling is a method of combining evidence from observational epidemiology and clinical trials to assist in clinical and health policy decision-making. It can estimate absolute benefits, risks and costs of long-term preventive strategies, and thus allow their precise targeting to individuals for whom they are safest and most cost-effective. Epidemiological modelling also allows explicit information about risks and benefits of therapy to be presented to patients, facilitating informed decision-making.

Efficacy of Lentivirus-mediated and MUC1 antibody-targeted VP22-TK/GCV suicide gene therapy for ovarian cancer

Transfer of the herpes simplex virus type I thymidine kinase (HSV-TK) gene into tumor cells using virus-based vectors in conjunction with ganciclovir (GCV) exposure provides a potential gene therapy strategy for the treatment of cancer. Effective gene therapy,, depends on the efficient transfer and specific targeting of therapeutic genes and their protein products to target cells. The purpose of this study was to investigate the anti-tumor effect of Lentivirus-mediated and MUC1 antibody-targeted VP22-TK/GCV suicide gene therapy in animal models. Mouse models were generated with intraperitoneal injection of human epithelial ovarian cancer cells 3AO, which are MUC1-positive. HTV-1-based lentiviral vectors carrying VP22-TK or scFv-VP22-TK were prepared. The animals were injected intraperitoneally with lentivirus containing scFv-VP22-TK, VP22-TK followed by GCV treatment. Combined treatment of lentivirus-expressed scFv-VP22-TK or VP22-TK with GCV inhibited the proliferation and prolonged survival times compared with the control vector. The survival time of animals treated with scFv-VP22-TK/GCV was significantly longer than that of animals treated with VP22-TK/GCV (p = 0.006). Conclusion: Our results suggest that MUC1 antibody-targeted VP22-TK/GCV suicide gene therapy can efficiently inhibit ovarian tumor growth and increase survival in a nude mouse model of ovarian carcinoma. These data support the development of this method for human clinical trials.