Alterations in liver, muscle, and adipose tissue insulin sensitivity in men with HIV infection and dyslipidemia

Dyslipidemia is common in patients with HIV infection. In this study, a two-stage euglycemic hyperinsulinemic clamp, with infusion of stable isotopically labeled tracers, was used to evaluate insulin action in skeletal muscle, liver, and adipose tissue in HIV-infected men with dyslipidemia (HIV-DL; plasma triglyceride >250 mg/dl and HDL <45 mg/dl; n=12), HIV-infected men without dyslipidemia (HIV w/o DL; n=12), and healthy men (n=6). Basal rates of glucose production (glucose R(a)), glucose disposal (glucose R(d)), and lipolysis (palmitate R(a)) were similar between groups. The relative suppression of glucose R(a) (63+/- 4, 77+/- 2, and 78+/- 3%, P=0.008) and palmitate R(a) (49+/-4, 63+/-3, and 68+/-3%, P=0.005) during ow-dose insulin infusion (plasma insulin approximately 30 microU/ml), and the relative stimulation of glucose R(d) (214+/-21, 390+/-25, and 393+/-46%, P=0.001) during high-dose insulin infusion (plasma insulin approximately 75 microU/ml) were lower in HIV-DL than in HIV w/o DL and healthy volunteers, respectively. Suppression of basal glucose R(a) correlated with plasma adiponectin (r=0.44, P=0.02) and inversely with plasma IL-6 (r=-0.49, P<0.001). Stimulation of glucose R(d) correlated directly with adiponectin (r=0.48, P<0.01) and inversely with IL-6 (r=-0.49, P=0.02). We conclude that dyslipidemia in HIV-infected men is indicative of multiorgan insulin resistance, and circulating adipokines may be important in the pathogenesis of impaired insulin action.

Ginkgo biloba leaf extract (EGb 761) enhances catalepsy induced by haloperidol and L-nitroarginine in mice

Ginkgo biloba extract EGb 761 has been reported to have therapeutic effects which have been attributed to anti-oxidant and free radical-scavenging activities, including a direct action on nitric oxide production. L G-nitro-arginine (L-NOARG), a nitric oxide synthase inhibitor, and haloperidol, a drug that blocks dopamine receptors, are both known to induce catalepsy in rodents. Nitric oxide has been shown to influence dopaminergic transmission in the striatum. The purpose of the present study was to evaluate the effect of the extract obtained from leaves of Ginkgo biloba tree EGb 761 on catalepsy induced by haloperidol or by L-NOARG. Albino Swiss mice (35-45 g, N = 8-12) received by gavage a single or repeated oral dose (twice a day for 4 days) of EGb 761 followed by ip injection of haloperidol or L-NOARG. After the treatments, the animals were submitted to behavioral evaluation using the catalepsy test. Acute treatment with 80 mg/kg EGb did not modify the catalepsy induced by L-NOARG but, the dose of 40 mg/kg significantly enhanced haloperidol-induced catalepsy measured at the 10th min of the test. After repeated treatment with 80 mg/kg EGb 761, a significant increase in the cataleptic effect produced by both haloperidol and L-NOARG was observed. These data show that repeated EGb 761 administration increases the effects of drugs that modify motor behavior in mice. Since the catalepsy test has predictive value regarding extrapyramidal effects, the possibility of pharmacological interactions between haloperidol and Ginkgo biloba extracts should be further investigated in clinical studies.

Dietary supplementation with monounsaturated and long-chain polyunsaturated fatty acids influences the liver structural recovery and hepatocyte binuclearity in female Wistar rats in experimental cirrhosis induced by thioacetamide

Oral administration of 300 mg/l thioacetamide (TAA) for 4 months causes hepatic lesions comparable to those described in alcoholic liver cirrhosis in humans and associated protein-energy malnutrition. In this sense, direct supplementation with monounsaturated fatty acids (MUFAs) and/or polyunsaturated fatty acids (PUFAs) might provide an advantage in the correction of the fatty acid deficiency in these patients. PUFAs are essential components of cell membranes maintaining its fluidity and function, important energy sources, and precursors of eicosanoids. Moreover, these fatty acids also modulate gene transcription, mRNA stability, and cellular differentiation.

METHODS

Fifty-four female Wistar rats (Interfauna Ibérica, Barcelona, Spain) weighing 110-120 g were used in this study. The animals were divided into two groups: one group was treated with 300 mg/l TAA dissolved in drinking water during 4 months, and the other group, which served as a control, was given water without TAA. To evaluate the changes induced by the administration of TAA for 4 months, TAA-treated (n = 7) and control animals (n = 5) were killed. Then, the TAA treatment was stopped and the rest of the animals in both TAA and control groups were divided into three experimental groups and three control groups which received for 2 weeks different type of diets. Using the TAA-induced liver cirrhosis model in rats, we analysed the effects of dietary supplementation with MUFAs and PUFAs on binuclearity and ultrastructure of hepatocytes. After TAA-induced cirrhosis, we analysed whether dietary supplementation with fatty acids may restore the normal percentage of binucleated cells, as well as the ultrastructure, nuclear area, and nuclear/cytoplasm index of hepatocytes.

RESULTS

Treatment with TAA causes cirrhosis characterized by the appearance of parenchyma nodules and fibrous septae, as well as qualitative and quantitative alterations in liver and plasma lipids. Our results indicate that dietary MUFAs support hepatocyte recovery regarding its ultrastructural and morphometric values. However, PUFAs-enriched diets (n-3 and n-3 + n-6) do not correct hepatomegaly, fibrosis or lipid accumulation. Thus, dietary PUFAs do not enhance hepatocyte recovery from morphological and ultrastructural alterations.

CONCLUSIONS

In our experimental model of cirrhosis, dietary supplementation with a high proportion of long-chain PUFAs (n-3 or n-6) negatively influences liver recovery. This negative effect was likely due to the increased susceptibility of cell membranes to lipid peroxidation, together with an alteration in lipid metabolism.

Comportement et conditions de travail exposant au sang : analyse des pratiques dans trois établissements de soins du Maroc

OBJECTIVE

As in other countries, Moroccan health-care workers are exposed to occupational blood exposure (OBE) hazards. The purpose of this study was to estimate the occupational safety and hygiene conditions determining the OBE risk for health-care workers. WORKERS AND METHODS: In March 2000, a multicentric study was carried out in Morocco on 420 health-care workers, with an anonymous questionnaire. The study included health-care workers in the Taza and Temara hospitals and health centers, as well as in a Rabat public medical analysis laboratory.

RESULTS

The participation rate was 67.8% (285/420). The population was mainly female (61%) with a mean age of 41.4 years (+/-7 years). Health-care workers answered that: occupational hygiene and safety were inadequate (55.1%); wearing single-use gloves was rare (34.5%); resheathing used needles was frequent (74.5%); safe containers were often missing (67%). In 1999, the annual average incidence of OBE was 1.5 (+/-4.3) per capita. If we consider the whole career of health-care workers, the incidence reached about 14.3+/-28.1 per capita. The absence of post-exposure chemoprophylaxis was the rule.

CONCLUSION

The study shows that there is a need to improve occupational hygiene and safety conditions for Moroccan health-care workers in order to reduce OBE hazards.

Latent TGF-beta binding proteins

Latent TGF-beta binding proteins are multidomain proteins with a common, highly repetitive structural organization and partially overlapping expression patterns. Latent TGF-beta binding protein-1, -3 and -4 bind latent TGF-beta. TGF-betas are normally secreted as latent complexes, consisting of the mature TGF-beta dimer non-covalently bound to its processed propeptide dimer plus a latent TGF-beta binding protein. The latent TGF-beta binding protein is covalently bound to the propeptide. These binding proteins may perform at least two functions: structural, as components of the matrix, and regulatory, as modulators of TGF-beta availability.

Churg-Strauss Syndrome Development during Asthma Therapy with Leukotriene Receptor Antagonists: Just a Coincidental Association?

A report on our clinical experience based on 3 male patients who developed Churg-Strauss syndrome (CSS) after standard oral montelukast use. All patients affected by moderate asthma and chronic hyperplastic rhinosinusitis were treated with inhaled corticosteroids and ß2 agonists. Systemic corticosteroid treatment consisted in oral daily prednisone in case 1, in short courses of oral betamethasone in case 2, and in remote and isolated administrations of oral betamethasone and intramuscular methylprednisolone in case 3. Because of the improvement of the asthma symptoms after montelukast use, patient 1 decided to take half the dose of prednisone for 10 days and patient 2 decided to discontinue systemic and inhaled corticosteroids for 45 days. Overt CSS was heralded by vasculitic skin lesions and developed in each patient with severe organ damage, consisting in renal, myocardial and gastrointestinal involvement. Remission was obtained by standard CSS therapy after montelukast withdrawal.

According to the unmasking hypothesis, antileukotriene treatment, by enabling the reduction in systemic corticosteroid therapy in case 1 and its discontinuation in case 2, might have only permitted the precipitation of the vasculitis. However antileukotriene-associated CSS reportedly occurred in systemic corticosteroid-naïve patients and relapsed in one patient after antileukotriene treatment. These observations lend support to the concept that the precipitation of the vasculitic phase may be associated with leukotriene modifier deleterious effects. In conclusion there is not enough evidence to prove that antileukotriene treatment plays a direct causative role in the pathogenesis of CSS. Further clinical and experimental research is required to clarify the antileukotriene associated CSS controversy.

Endothelial Dysfunction in Rheumatoid Arthritis is Improved by Anti-Tumor Necrosis Factorα Treatment

Rheumatoid arthritis (RA) is associated with excess cardiovascular morbidity and mortality. TNFα plays a pivotal role in causing both RA synovial damage and atherosclerosis, also by inducing endothelial dysfunction. The aim of the present study was to assess the occurrence of endothelial dysfunction and the effects of anti-TNFα antagonism on endothelial function in RA. Ten RA women with Disease Activity Score (DAS) ≥ 3.7 despite treatment with at least two disease-modifying antirheumatic drugs for 4 months underwent anti-TNFα treatment with infliximab or etanercept.

Endothelium-dependent vasodilation was significantly lower than normal (3.8±3.7 % vs. 13.7 ±5.1, p≤0.05), thus demonstrating the presence of endothelial dysfunction in our RA patient population. Anti-TNF- treatment significantly improved flow-mediated vasodilation, which increased from baseline values of 3.8±3.7% to 10.9±6.6% (p<0.05) at day 1, to 13.4±5.4 % (p < 0.05) at week 1, to 12.7±5.3 % (p<0.05) at week 2 and to 15.5±5.2 % at week 6 (p≤0.05). There was no significant difference between two anti-TNFα treatments regarding mean percentage increase of flow-mediated vasodilation during treatment. RA clinical improvement was demonstrated by a significant decrease in the DAS score (from 6.26±1.6 to 5.26 1.38, p < 0.05) associated to a marked decrease of acute phase reactants serum levels. The present study supports the hypothesis of the pivotal role for TNFα as a mediator of systemic and vascular wall inflammation in RA.

Exogenous nucleosides modulate the expression of rat liver extracellular matrix genes in single cultures of primary hepatocytes and a liver stellate cell line and in their co-culture

BACKGROUND & AIMS

We have previously reported the antifibrotic effect of dietary nucleotides in cirrhotic rats. In this work, we used primary rat hepatocytes, a liver stellate cell line (CFSC-2G) and co-cultures of both cell types to investigate the effects of exogenous nucleosides on the gene expression of various extracellular matrix components and on markers of liver function, and to ascertain whether the effects found in vivo are due to CFSC-2G, hepatocytes, or are the consequence of cell-cell interactions.

RESULTS

Nucleosides enhanced fibronectin, laminin, and alpha1(I) procollagen levels in CFSC-2G and hepatocytes, as well as collagen synthesis and secretion in CFSC-2G. In contrast, nucleosides lowered fibronectin, laminin and alpha1(I) procollagen levels, and decreased collagen synthesis in co-cultures. Matrix metalloproteinase-13 content and collagen secretion increased in co-cultures incubated with nucleosides. Albumin increased in hepatocytes and co-cultures incubated in the presence of nucleosides.

CONCLUSIONS

Nucleosides modulate the production of extracellular matrix in single cultures of hepatocytes and of CFSC-2G, and in co-cultures. This effect seems to be regulated at the translational level. The opposite behavior of single cultures and co-cultures is probably due to the fact that the latter model reproduces many of the physical and functional relationships observed in vivo between hepatocytes and stellate cells.

Exogenous nucleosides alter the intracellular nucleotide pool in hepatic cell cultures. Implications in cell proliferation and function

BACKGROUND & AIMS

Dietary nucleotides are reported to influence the growth and functioning of the liver. The objective of the study was to evaluate the uptake and incorporation of exogenous nucleosides by hepatic cells, and the potential implications for cell proliferation and function.

METHODS

Liver stellate cell line CFSC-2G and primary hepatocytes in single and mixed cultures were exposed to mixtures of nucleosides and the concentrations of nucleoside derivatives were determined in the cultures, by high-performance liquid chromatography. Cell proliferation (DNA synthesis, cell cycle) and function (adenylate charge, albumin content, mitochondrial succinate dehydrogenase activity) were also evaluated.

RESULTS

The exogenous nucleosides increased the intracellular concentrations of UTP, UDP-glucose, CDP-choline and NAD(+), in the single cultures of CFSC-2G and hepatocytes. Modification of the intracellular nucleotide pool paralleled changes in cell functional status, as indicated by increased adenylate charge and albumin content in hepatocyte cultures and in their co-cultures with CFSC-2G, and by increased succinate dehydrogenase activity in hepatocytes.

CONCLUSION

Exogenous nucleosides were taken up by CFSC-2G and hepatocytes, which modified the intracellular concentrations of nucleotides, improved the functional status of hepatocytes, and partially restored the impaired adenylate charge of the co-cultures.

Genetic control of serum IgE levels: a study of low molecular weight protein tyrosine phosphatase

Protein tyrosine phosphatases (PTPases) have recently been recognized as important modulators of various signal transduction pathways in immune cells. Genetic polymorphisms have been described in genes codifying for members of this family of enzymes, and the genetics of PTPases is predicted to play an important role in the etiology of immune diseases and of their clinical variability. The low molecular weight protein tyrosine phosphatase (ACP1 or LMPTP) is one of the few PTPases with a known genetic polymorphism, and has been proposed to be associated with atopic dermatitis in a small sample from an Italian population. In this paper we describe the association of the ACP1 polymorphism with total IgE levels in two independent samples from English and Italian populations. In both the samples the mean value of serum IgE is lower among subjects carrying the BC genotype than in other ACP1 genotypes. The BC genotype is associated with the highest total ACP1 enzymatic activity. Our data suggest that one or both of the ACP1 isoforms exert an inhibitory role on some signal transduction pathway relevant for IgE hyperproduction.

Low molecular weight PTP-IL-4RA interaction in atopy predisposition

We recently described a protective effect of the low molecular weight protein tyrosine phosphatase (LMPTP) BC genotype, associated with the highest total enzymatic activity, against high serum IgE levels both in the English and the Italian populations. Here we test the hypothesis of a role of LMPTP in the negative modulation of IL-4 signal transduction checking for genetic interaction between interleukin-4 receptor alpha chain (IL-4RA) genetic polymorphisms and LMPTP polymorphism in the predisposition to high total IgE levels in the English population. We find a significant interaction between LMPTP polymorphism and the intracellular Gln/Arg polymorphism in position 551 of IL-4RA. Our data support the hypothesis of a direct or indirect biochemical interaction between LMPTP and IL-4RA resulting in different modulation of IL-4 signal transduction among joint genotypes.

IL-4 receptor alpha chain genetic polymorphism and total IgE levels in the English population: two-locus haplotypes are more informative than individual SNPs

The IL-4RA locus encodes for the alpha chain of the IL-4 receptor, and is both a functional and positional candidate gene for atopy and allergic disease. Recently Ober et al. have shown that the study of haplotypes at multiple loci in the IL-4RA gene could be more informative than the separate study of single nucleotide polymorphisms (SNPs). One hundred and fifty subjects affected by atopic asthma and 150 healthy control subjects were studied in the English population (Oxford district). Subjects and controls were genotyped for the Ile50Val, Ser478Pro and Gln551Arg polymorphism of the IL-4 receptor alpha chain. The distribution of haplotypes 50-478 shows a highly significant association with IgE levels. In particular, the haplotype Val50/Pro478 is much less frequent in subjects with IgE levels > 100 U mL-1 than in those with IgE levels < 100 U mL-1. Furthermore, the distribution of haplotype 50-551 shows a weak association with IgE levels that is lacking for 478-551 haplotypes. A lower frequency of the Val50/Pro478 haplotype is also observed among asthmatic subjects as compared to healthy controls. With regard to individual SNPs (50 478 and 551), no significant association has been observed with IgE levels or with asthma, thus confirming the higher informative value of the haplotype analysis as compared to separate study on SNPs.

Targeted gene transduction of mammalian cells expressing the HER2/neu receptor by filamentous phage

Screening a random peptide library displayed on phage as fusion to the major capsid protein pVIII identified a ligand binding the human epidermal growth factor receptor 2 (HER2) specifically. By mutating the sequence of this ligand, a "secondary" library was generated, whose panning on HER2-positive cells isolated a phage-borne peptide with increased specific binding to HER2 (phage NL1.1). The same peptide recognised HER2 specifically when expressed as an N-terminal fusion to the minor coat protein pIII. Phage NL1.1 was engineered to include a mammalian expression cassette for a reporter gene within its genome. This modified phage transduced HER2-expressing cells with very high specificity (more than 1000-fold that of parental HER2-negative cells) and with an efficiency comparable to that of chemical transfection protocols. The gene delivery process was remarkably fast, requiring less than 15 minutes incubation of phage with target cells to generate detectable levels of gene expression.

Long-term modulation of HERG channel gating in hypoxia

Using the patch-clamp technique, we analysed changes in the biophysical properties of HERG potassium channels in neuroblastoma cells long-term exposed to hypoxia. In this condition, HERG channels underwent a profound modulation that consisted of: (i) a slowing in open-close kinetics; (ii) a marked hyperpolarizing shift in voltage dependence of steady-state activation; and (iii) a slowing of the inactivation removal. The overall physiological impact of these changes in neuroblastoma cells is an increase in the HERG window current in the range of the resting potential (V(REST)), which varied between -40 and -30 mV. Such a current modulation is suitable to stabilise the resting potential (V(REST)) in hypoxic environments.