Comparative molecular field analysis (CoMFA) and docking studies of non-nucleoside HIV-1 RT inhibitors (NNIs)

A set of TIBO derivatives endowed with reverse transcriptase (RT) inhibitory activity were analyzed by comparative molecular field analysis (CoMFA). Besides conventional steric and electrostatic fields, molecular lipophilicity potential (MLP) was also used as a third field in CoMFA. An informative and statistically significant model (q2 = 0.70, r2 = 0.90, s = 0.46) was obtained by taking into account the three field types together. The key molecular determinants governing the RT inhibition by TIBO congeners were detected at the 3-D level by a careful analysis of the CoMFA isocontour maps. To challenge the predictive ability of the CoMFA model, an external set of thiazolobenzimidazole (TBZ) derivatives were examined. Good predictions, suggesting a similar binding mode for TIBO and TBZ derivatives, emerged. Flexible docking experiments on TBZ, TIBO and other NNIs confirmed common binding characteristics, as found out also by CoMFA, and moreover a good correlation between calculated binding energies and inhibitory potency was found.

Liver transplantation for hepatocellular carcinoma in cirrhotic patients

BACKGROUND

Hepatocellular carcinoma (HCC) in patients with cirrhosis, due to a limited liver reserve, is often deemed unresectable, even at an early stage.

METHODS

In order to evaluate the ongoing transplant programme for cirrhotic patients with HCC at Royal Prince Alfred Hospital, the results of liver transplantation (LTx) for HCC were analysed and the patient actuarial survival was compared with that of those LTx patients without malignancy.

RESULTS

A total of 441 LTx were performed in 404 patients between January 1986 and April 1998. Twenty-four LTx recipients (22 men; two women) of mean age 49 (15-62) years had HCC. Twenty-one had underlying aetiology for their cirrhosis (hepatitis B: n = 9; hepatitis C: n = 8; hepatitis B and C: n = 1; haemochromatosis: n = 1; autoimmune hepatitis: n = 1; alcoholism: n = 1), while three patients had cryptogenic cirrhosis. Six patients had incidental tumours and another two cases were of the fibrolamellar type. The average tumour size and tumour number were 2.9 (0.4-11.5) cm and 1.3 (1-4), respectively. Operative mortality was 4.2% (1/24). The HCC recurrence appeared in one (4.2%) patient (with a 11.5-cm HCC) who died 18 months after LTx. A further two patients died (one graft failure from recurrent hepatitis C and one from fungal sepsis) during follow-up. The overall 1- and 3-year actuarial patient survival rates were 87% and 76%, respectively, and that of patients with benign causes (n = 369) were 77% and 72% (P = NS).

CONCLUSION

With careful patient selection, long-term tumour-free patient survival can be achieved. The results support an active transplant programme for selected HCC.

Effect of amplitude modulated RF radiation on calcium ion efflux and ODC activity in chronically exposed rat brain

The effect of exposing rats to amplitude modulated radiofrequency radiation (112 MHz modulated to 16 Hz) during development and growth has been examined. Wistar rats (35 days old) when exposed at above frequency at the power level 1.0 mW/cm2 (SAR, 0.75 W/kg) for 35 days showed enhanced ornithine decarboxylase activity and Ca2+ efflux in brain indicating potential health hazards due to exposure.

Affinity-driven peptide selection of an NFAT inhibitor more selective than cyclosporin A

The flow of information from calcium-mobilizing receptors to nuclear factor of activated T cells (NFAT)-dependent genes is critically dependent on interaction between the phosphatase calcineurin and the transcription factor NFAT. A high-affinity calcineurin-binding peptide was selected from combinatorial peptide libraries based on the calcineurin docking motif of NFAT. This peptide potently inhibited NFAT activation and NFAT-dependent expression of endogenous cytokine genes in T cells, without affecting the expression of other cytokines that require calcineurin but not NFAT. Substitution of the optimized peptide sequence into the natural calcineurin docking site increased the calcineurin responsiveness of NFAT. Compounds that interfere selectively with the calcineurin-NFAT interaction without affecting calcineurin phosphatase activity may be useful as therapeutic agents that are less toxic than current drugs.

Synthesis and biological activity of novel 1H,3H-thiazolo[3,4-a]benzimidazoles: non-nucleoside human immunodeficiency virus type 1 reverse transcriptase inhibitors

Using a known human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase inhibitor (NNRTI), 1-(2,6-difluorophenyl)-1H,3H-thiazolo[3,4-a]benzimidazole (TBZ NSC 625487) as the lead structure for drug design, a series of novel 1H,3H-thiazolo[3,4-a]benzimidazole derivatives substituted on the benzene-fused ring was prepared. Their in vitro anti-HIV-1 activity, as well as their inhibitory effects on the viral reverse transcriptase, were evaluated. The structure-activity relationships for these compounds are described and the results suggest that the apolar binding pocket of RT, into which the NNRTIs must fit, can accommodate only groups with a limited size and shape.

A case of stapler pin in the root canal--extending beyond the apex

There have been several reports describing the placement, by patients, of foreign objects into exposed pulp chambers and canals. In the present case, a 13-year-old patient reported with complaints of pain and a history of inserting a foreign object into the root canal of the left central incisor. On examination the foreign body was found to be a stapler pin which was projecting 5 millimeters from the apical foramen. Foreign bodies discovered from the root canal have varied from radiolucent objects like wooden tooth picks or tooth brush bristles to radioopaque materials like paper pins, needles, pencil leads etc. In the present case, despite our best efforts, the patient did not agree to undergo any treatment except for the extraction of the left central incisor.

Preponderance of hypokalaemia as a cause of acute onset quadriparesis in northern India/southern Nepal

Of 68 patients who were admitted with acute quadriparesis to a hospital in northern India, over 70% were found to be hypokalaemic. The most common cause of hypokalaemia was that associated with gastroenteritis (54%). These patients had all received intravenous fluids previously. It is likely that their hypokalaemia was caused by gastrointestinal loss compounded by parenteral fluid replacement. The next most common group of hypokalaemia-associated quadriparesis had no obvious cause for hypokalaemia (38%). Hypokalaemia-induced quadriparesis is a potentially life-threatening illness which can be readily treated with potassium supplements. The physician should consider hypokalaemia in patients who present with acute onset quadriparesis, and even if diagnostic tests for hypokalaemia are not available, should consider a judicious trial of potassium supplementation empirically, provided that there are no contraindications.

NFAT5, a constitutively nuclear NFAT protein that does not cooperate with Fos and Jun

NFAT transcription factors are related to NF-kappaB/Rel proteins and form cooperative complexes with Fos and Jun on DNA. We have identified an NFAT-related protein, NFAT5, which differs from the conventional NFAT proteins NFAT1-4 in its structure, DNA binding, and regulation. NFAT5 contains a NFAT-like Rel homology domain, conserves the DNA contact residues of NFAT1-4, and binds DNA sequences similar to those found in the regulatory regions of well-characterized NFAT-dependent genes. However, it lacks the majority of Fos/Jun contact residues and does not bind cooperatively with Fos and Jun to DNA. Unlike NFAT1-4, whose nuclear import is tightly regulated by calcineurin-mediated dephosphorylation, NFAT5 is a constitutively nuclear phosphoprotein regardless of calcineurin activation. These features suggest that unlike the conventional NFAT proteins, NFAT1-4, which activate gene transcription by integrating inputs from calcium/calcineurin and protein kinase C/mitogen-activated protein kinase signaling pathways, NFAT5 participates in as-yet-unidentified signaling pathways in diverse immune and nonimmune cells.

Chromatin-based regulatory mechanisms governing cytokine gene transcription

On initial contact with antigen, naive T cells differentiate and acquire effector characteristics, including the ability to transcribe specific cytokine genes rapidly and at high levels on subsequent exposure to antigen. Several effector T-cell subsets showing distinct patterns of cytokine gene transcription have been described. The patterns of cytokine expression in response to pathogenic challenges have a significant impact on the outcome of immune and inflammatory reactions. Here we review recent studies suggesting that the ability of naive T cells to differentiate into specific cytokine-expressing cells is regulated by epigenetic changes in the accessibility and chromatin structure of cytokine genetic loci. Antigen and cytokine stimulation of naive T cells activates diverse intracellular signaling pathways, which result in chromatin remodeling and demethylation of cytokine genes. These changes are likely to increase, in a stable and heritable fashion, the accessibility of these genes to the basal transcriptional machinery. Chromatin-based regulatory mechanisms may explain several features of cytokine gene expression in effector versus naive T cells, including their monoallelic expression, coordinate regulation, and stable maintenance in memory T cells. The hypothesis of epigenetic changes occurring during T-cell differentiation provides a framework for a comprehensive understanding of cytokine expression by T cells.

Prevalence of dental caries among school children of Moodbidri

This survey was carried out among 2902 children aged between 5 and 12 years attending 13 primary schools in various areas of Moodbidri, in Udupi district. The oral health status was assessed using the simplified WHO Oral Health Assessment Form. The caries prevalence was found to be 76.9%. The mean DMFT was 0.78 and the mean deft was 3.48. Although the mean DMFT score between males and females did not show any significant difference, the mean deft was found to be higher among males compared to females. It was also found that the mean DMFT score increased with age whereas the mean deft score decreased with age.

Reciprocal modulatory interaction between human immunodeficiency virus type 1 Tat and transcription factor NFAT1

Human immunodeficiency virus type 1 (HIV-1) gene expression is regulated by interactions between both viral and host factors. These interactions are also responsible for changes in the expression of many host cell genes, including cytokines and other immune regulators, which may account for the state of immunological dysregulation that characterizes HIV-1 infection. We have investigated the role of a host cell protein, the transcription factor NFAT1, in HIV-1 pathogenesis. We show that NFAT1 interacts with Tat and that this interaction, which involves the major transactivation domain of NFAT1 and the amino-terminal region of Tat, results in a reciprocal modulatory interplay between the proteins: whereas Tat enhances NFAT1-driven transcription in Jurkat T cells, NFAT1 represses Tat-mediated transactivation of the HIV-1 long terminal repeat (LTR). Moreover, NFAT1 binds to the kappaB sites on the viral LTR and negatively regulates NF-kappaB-mediated activation of HIV-1 transcription, by competing with NF-kappaB1 for its binding sites on the HIV-1 LTR. Tat-mediated enhancement of NFAT1 transactivation may explain the upregulation of interleukin 2 and other cytokines that occurs during HIV-1 infection. We discuss the potentially opposing roles of NFAT1 and another family member, NFAT2, in regulating gene transcription of HIV-1 and endogenous cytokine genes.

Oral health status of the institutionalized elderly in Mangalore, India

This study was carried out among 287 institutionalized elderly aged 60 years and above residing in Mangalore. The oral health status was assessed using the modified Oral Health Assessment Form. The most frequently observed periodontal condition was shallow pockets seen in 32.29% of the dentate subjects. None of the subjects were found to have a completely healthy periodontium. The dental caries prevalence was found to be 77.6%. The mean DFT of the dentate subjects was 3.64 with the mean DT and FT being 3.58 and 0.06 respectively. The mean DFT was found to increase with advancing age. Findings also suggest that edentulousness is directly proportional to the period of stay in the old age home and inversely proportional to the mobility of the individual.

Central administration of leptin to ovariectomized ewes inhibits food intake without affecting the secretion of hormones from the pituitary gland: evidence for a dissociation of effects on appetite and neuroendocrine function

We have studied the effect of leptin on food intake and neuroendocrine function in ovariectomized ewes. Groups (n = 5) received intracerebroventricular infusions of either vehicle or leptin (20 microg/h) for 3 days and were blood sampled over 6 h on days -1, 2, and for 3 h on day 3 relative to the onset of the infusion. The animals were then killed to measure hypothalamic neuropeptide Y expression by in situ hybridization. Plasma samples were assayed for metabolic parameters and pituitary hormones. Food intake was reduced by leptin, but did not change in controls. Leptin treatment elevated plasma lactate and nonesterified fatty acids, but did not affect glucose or insulin levels, indicating a state of negative energy balance that was met by the mobilization of body stores. Pulse analysis showed that the secretion of LH and GH was not affected by leptin treatment, nor were the mean plasma concentrations of FSH, PRL, or cortisol. Expression of messenger RNA for neuropeptide Y in the arcuate nucleus was reduced by the infusion of leptin, primarily due to reduced expression per cell rather than a reduction in the number of cells observed. Thus, the action of leptin to inhibit food intake is dissociated from neuroendocrine function. These results suggest that the metabolic effects of leptin are mediated via neuronal systems that possess leptin receptors rather than via endocrine effects.

Modulatory potential of Spirulina fusiformis on carcinogen metabolizing enzymes in Swiss albino mice

The modulatory potential of Spirulina fusiformis was observed on the hepatic and extrahepatic carcinogen metabolizing enzymes in Swiss albino mice at a dose of 800 mg/kg b.w. given orally. A significant reduction in the hepatic cytochrome P-450 content was observed in the group treated with Spirulina in comparison with the control group. The hepatic glutathione S-transferase activity was induced significantly by Spirulina treatment. There was no change in the extrahepatic glutathione S-transferase activity after the animals were fed with Spirulina.

Molecular regulation of cytokine gene expression during the immune response

Cytokine expression by immune system cells plays an important role in the regulation of the immune response. On first encounter with antigen, naive CD4+ T helper (Th) cells differentiate into cytokine-producing effector cells. Two types of effector cells characterized by their distinct expression of cytokine profiles have been described. Th1 cells produce IL-2 and IFN-gamma, whereas Th2 cells produce IL-4, IL-5, IL-6, IL-10, and IL-13. In many pathological situations, the balance between Th1 and Th2 immune responses determines the outcome of diverse immunologically mediated clinical syndromes including infectious, autoimmune, and allergic diseases. However, the molecular basis for the tissue-specific expression of Th1/Th2-like cytokines has remained elusive. In this review we evaluate the possible in vivo role of different transcription factors and transcriptional mechanisms in T cell differentiation and the immune response.

Effect of antidiabetic compounds on glyoxalase I activity in experimental diabetic rat liver

The activity of glyoxalase I from the soluble fraction of diabetic rat liver was found to decrease as compared to the control. Sodium orthovanadate in drinking water and Trigonella foenum graecum seed powder when administered to these diabetic animals were found to reverse the activity of glyoxalase I to control values. A combination of the above two antidiabetic compounds showed a better reversal. Vanadate and Trigonella seed powder treatment separately to diabetic rats also normalized hyperglycemia together with glyoxalase I activity. A combination of vanadate and Trigonella seed powder also restored the other general parameters of the diabetic animals.