Regulation of type 1 diabetes by a self-MHC class II peptide: role of transforming growth factor beta (TGF-beta)

The present study was undertaken to analyze the regulatory T cells generated in response to class I derived self-I-A beta(g7) (54-76) peptide. It was observed T cells from young unprimed type 1 diabetes (T1D) prone NOD mice did not respond to self-I-A beta(g7) (54-76) peptide although T cells from primed young NOD mice showed a strong response. T cells from young unprimed BALB/c mice responded to self-I-A beta(d) (62-78) peptide. However, a breakdown of tolerance to these peptides was observed with age in both the strains. Culture supernatant from I-A beta(g7) (54-76) peptide-primed cells secreted large amounts of TGF-beta and inhibited T cell responses in allogeneic-MLR. Further, I-A beta(g7) (54-76) peptide specific T cell lines from young (I-A.Y) and diabetic (I-A.D) NOD mice were established. I-A.Y secreted IL-4, TGF-beta and IL-10 while I-A.D T cell line secreted IL-10 and IFN-gamma. We found that I-A.D T cell line induced diabetes when transferred in NOD/SCID mice but I-A.Y T cell line did not induce disease. These results show that immunization of NOD mice with I-A beta(g7) (54-76) peptide at a younger age induces a regulatory T cell response suggesting that correcting the defects in immunoregulatory mechanisms using self-MHC peptides may be one of the approaches to prevent autoimmune diseases like T1D.

Unnecessary peripheral intravenous catheterisation on an acute medical admissions unit: a preliminary study

BACKGROUND: The ability to secure peripheral intravenous access is regarded as a basic medical skill that is often required for the management of patients admitted to acute medical admission wards. The decision to insert a peripheral intravenous catheter (PIC) is usually taken by relatively inexperienced members of the acute medical team and is primarily based on 'traditional' or 'routine' practice, rather than on an assessment of need. Furthermore, there appears to be little recognition of the potentially serious adverse events associated with PIC insertion. METHOD: We conducted a prospective study to evaluate unnecessary PIC insertion in a United Kingdom teaching hospital's acute medical admissions unit. RESULTS: Of the 338 patients included in the study, 272 (80.5%) received a PIC. Of these, 179 patients (66%) received a PIC that had been used by the post-on-call ward round. Of the 93 patients (34%) with an unused PIC, 30 patients (11%) had been catheterised inappropriately by the study criteria. CONCLUSIONS: Despite our use of conservative criteria for PIC insertion, a notable level of inappropriate peripheral intravenous catheterisation was identified. A hypothetical cost-minimisation analysis is presented and a care pathway for best practice proposed.

Ligand and coactivator recruitment preferences of peroxisome proliferator activated receptor alpha

The mechanism by which ligands of nuclear receptors show differential effects on gene transcription is not fully understood, but is believed to result in part from the preferential recruitment and/or displacement of coactivators and corepressors. We have explored the interaction of several known ligands and the nuclear receptor (peroxisome proliferator activated receptor alpha, PPARalpha) using scintillation proximity assay (SPA) and the interaction of LXXLL containing peptides derived from three coactivators (SRC-1, CBP and PGC-1) with PPARalpha in the presence of PPARalpha agonist ligands using fluorescence resonance energy transfer (FRET). The EC(50)s of the individual ligands for recruitment showed the same rank order regardless of the coactivator peptide used, with GW2331<WY14643=ciprofibrate<L165041<gemfibrozil. Similarly, for all ligands tested, the rank order of EC(50) for peptide recruitment was CBP<PGC-1<SRC-1. These data suggest that for these LXXLL coactivator peptides, the ligands do not substantially differ in their preferences. Partial agonism was observed with ciprofibrate and PGC-1 and gemfibrozil and CBP giving a lower FRET at saturation than with the other ligands. This suggests that ciprofibrate and gemfibrozil induce a different conformation to the receptor-PGC-1 and receptor-CBP complex, respectively. In cotransfection assays, unexpected differences in potencies and efficacies were observed and the rank order of EC(50)s for activation differed from that predicted by FRET assays. In most cases, the presence of a coactivator peptide led to decrease in the EC(50)s seen in FRET assays compared to the K(i)s observed in binding to receptor only, consistent with the lower EC(50)s obtained in the transfection assays. Our data demonstrate that ligand induced coactivator preferences of PPARalpha contribute to transcription potency and efficacy.

PPARs: Versatile Targets for Future Therapy for Obesity, Diabetes and Cardiovascular Diseases

Peroxisome proliferator activated receptors (PPARs) are fertile targets for drug discovery. They are targets for two widely used classes of drugs, the fibrates and thiazolidinediones. Remarkable advances have been made in our understanding of the mechanism of action of these receptors over the last 10 years. Further research and development of the three identified PPARs, PPARalpha, PPARbeta and PPARgamma, may help develop more efficacious drugs in the treatment of dyslipidemia, cardiovascular diseases, obesity and diabetes. (c) 2002 Prous Science. All rights reserved.

Generation of multiple farnesoid-X-receptor isoforms through the use of alternative promoters

Bile acid biosynthesis is regulated by both feed-forward and feedback mechanisms involving a cascade of nuclear hormone receptors. Feed-forward regulation of the rate limiting enzyme in bile acid biosynthesis is provided by oxysterols through liver-X-receptor alpha (NR1H3), while feedback regulation is provided by bile acids through farnesoid-X-receptor (FXR) (NR1H4). The Syrian golden hamster provides a useful model for studying lipid metabolism. The hamster metabolizes and transports dietary cholesterol in a similar manner to humans, with the resulting lipid profile being more similar to the human profile than that of other rodent models. Cloning of Fxr from Syrian golden hamster revealed four hamster Fxr splice variants that altered the N-terminal activation domain or the hinge region between the DNA and ligand binding domains. Human genomic sequence and data from hamster Fxr were used to identify and clone a novel human FXR isoform resulting from the use of an alternative promoter. RNA expression analysis indicates that the two human FXR isoforms are differentially expressed in developmental and tissue-specific patterns and are likely to provide a mechanism for cell-specific FXR-dependent transcriptional activity.

Effects of adenosine receptor subtype A1 on ventricular and renal function

The adenosine subtype 1 (A1) receptor, which may influence cardiac function and modulate renal function, may have particular relevance in congestive heart failure (CHF). However, the effects of A1 receptor inhibition in the setting of CHF are poorly defined. Systemic hemodynamics and indices of renal function were measured in pigs with pacing-induced CHF at 240 bpm for 3 weeks (n = 10) before and after A1 receptor blockade with 100 microg of BG9719 (1,3-dipropyl-8-[2-(5,6-epoxynorbornyl)]xanthene) or in CHF pigs after infusion of vehicle only (n = 10). Heart rate, mean aortic pressure, and left ventricular peak pressure increased following A1 blockade in the CHF group, consistent with an adenosine inhibitory effect. However, cardiac output and global measures of vascular resistance did not significantly change following A1 blockade. Urine output increased twofold and sodium clearance increased threefold following A1 blockade (p < 0.05). Creatinine clearance increased following A1 blockade (127 +/- 17 vs. 62 +/- 7 ml/min, p < 0.05). Selective A1 receptor blockade improved glomerular filtration rate and induced a natriuresis and diuresis in a model of CHF without adverse effects on cardiac function. These unique results suggest that renal A1 receptor activation may contribute to the reduced renal function associated with CHF.

Amplification of the androgen receptor may not explain the development of androgen-independent prostate cancer

OBJECTIVE

To examine the role of androgen receptor (AR) gene amplification and aneusomy of the X chromosome in the development of antiandrogen-resistant prostate cancer.

PATIENTS AND METHODS

Twenty patients with prostate cancer resistant to androgen-deprivation therapy were selected for study. The records of patients with tumours before and after antiandrogen therapy, and with a full clinical follow-up, were retrieved. AR gene amplification and X chromosome copy number were assessed by fluorescence in situ hybridization using a labelled probe at locus Xq11-13 for the AR gene and a labelled alpha-satellite probe for the X chromosome. At least 20 nuclei were scored over three tumour areas by two independent observers.

RESULTS

Aneusomy of the X chromosome was reported respectively in seven (35%) and 11 (55%) tumours before and after hormone relapse, the AR gene copy number was increased in seven (35%) and 13 (65%), respectively, and AR gene amplification was detected in one (5%) and three (15%), respectively. Neither increased AR copy number nor AR amplification in primary tumours precluded a biological response to androgen-deprivation therapy.

CONCLUSION

The rate of AR gene amplification is too low to be solely responsible for the development of antiandrogen-resistant prostate cancer. Also, the presence of amplified AR and cells aneusomic for the X chromosome in primary tumours that respond to androgen-deprivation therapy suggests that an increase in AR gene copy number does not prevent a tumour from responding to this therapy. Therefore other mechanisms which could cause hormone-refractory prostate cancer must be investigated before it is understood why so many patients relapse with this disease.

Myocardial and interstitial matrix metalloproteinase activity after acute myocardial infarction in pigs

A structural event during the evolution of a myocardial infarction (MI) is left ventricular (LV) remodeling. The mechanisms that contribute to early changes in LV myocardial remodeling in the post-MI period remain poorly understood. Matrix metalloproteinases (MMPs) contribute to tissue remodeling in several disease states. Whether and to what degree MMP activation occurs within the myocardial interstitium after acute MI remains to be determined. Adult pigs (n = 15) were instrumented to measure regional myocardial function and interstitial MMP levels within regions served by the circumflex and left anterior descending arteries. Regional function was measured by sonomicrometry, and interstitial MMP levels were determined by selective microdialysis and zymography as well as by MMP interstitial fluorogenic activity. Measurements were performed at baseline and sequentially for up to 3 h after ligation of the obtuse marginals of the circumflex artery. Regional fractional shortening fell by over 50% in the MI region but remained unchanged in the remote region after coronary occlusion. Release of soluble MMPs, as revealed by zymographic activity of myocardial interstitial samples, increased by 2 h post-MI. The increased zymographic activity after MI was consistent with MMP-9. Myocardial interstitial MMP fluorogenic activity became detectable within the ischemic region as early as 10 min after coronary occlusion and significantly increased after 1 h post-MI. MMP fluorogenic activity remained unchanged from baseline values in the remote region. The present study demonstrated that myocardial MMP activation can occur within the MI region in the absence of reperfusion. These unique results suggest that MMP release and activation occurs within the ischemic myocardial interstitium in the early post-MI period.

Peroxisome proliferator-activated receptor subtype-specific regulation of hepatic and peripheral gene expression in the Zucker diabetic fatty rat

Fibrates and thiazolidinediones are used clinically to treat hypertriglyceridemia and hyperglycemia, respectively. Fibrates bind to the peroxisome proliferator-activated receptor (PPAR)-alpha, and thiazolidinediones are ligands of PPAR-gamma. These intracellular receptors form heterodimers with retinoid X receptor to modulate gene transcription. To elucidate the target genes regulated by these compounds, we treated Zucker diabetic fatty rats (ZDF) for 15 days with a PPAR-alpha-specific compound, fenofibrate, a PPAR-gamma-specific ligand, rosiglitazone, and a PPAR-alpha/-gamma coagonist, GW2331, and measured the levels of several messenger RNAs (mRNAs) in liver by real-time polymerase chain reaction. All 3 compounds decreased serum glucose and triglyceride levels. Fenofibrate and GW2331 induced expression of acyl-coenzyme A (CoA) oxidase and enoyl-CoA hydratase and reduced apolipoprotein C-III and phosphoenolpyruvate carboxykinase mRNAs. Rosiglitazone modestly increased apolipoprotein C-III mRNA and had no effect on expression of the other 2 genes in the liver but increased the expression of glucose transporter 4 and phosphoenolpyruvate carboxykinase in adipose tissue. We identified a novel target in liver, mitogen-activated phosphokinase phosphatase 1, whose down-regulation by PPAR-alpha agonists may improve insulin sensitivity in that tissue by prolonging insulin responses. The results of these studies suggest that activation of PPAR-alpha as well as PPAR-gamma in therapy for type 2 diabetes will enhance glucose and triglyceride control by combining actions in hepatic and peripheral tissues.

Usefulness of calcium scoring using electron beam computed tomography and noninvasive coronary angiography in patients with suspected coronary artery disease

The aim of this study was to investigate the reliability of calcium scoring (CS) and electron beam computed tomographic angiography (EBCTA) as a noninvasive tool in the diagnosis of coronary artery disease (CAD): 93 consecutive patients (aged 59 +/- 9 years) with symptoms suspicious for CAD underwent CS. In 87 of these subjects, an additional EBCTA investigation was performed. Using receiver-operating characteristic curve analysis, we determined a calcium score cut point providing an overall sensitivity of 80% and a specificity of 72% in detecting patients with CAD. For clinical purposes the use of cut points is difficult. We therefore determined score ranges providing >80% specificity (high score range) and >85% sensitivity (low score range) and determined the scores between these ranges as equivocal borderline scores. Calculated on a per-segment basis in assessable proximal and midcoronary segments, the sensitivity for detecting coronary stenoses >50% was 78%, and the specificity was 93%. Thus, 32 of 44 patients with significant CAD and 24 of 49 patients without CAD were correctly classified. The combination of CS and EBCTA predicted CAD in 77% (72 of 93) of patients. No or low calcium scores provided high specificity for ruling out CAD. The addition of EBCTA in those patients improved sensitivity. In patients with high calcium scores, accuracy of EBCTA was not significantly different from CS alone (72% vs 83%), whereas in patients with borderline scores it was significantly superior (80% vs 58%, p <0.03). Thus, the complementary use of CS and EBCTA appears beneficial, particularly in patients with borderline scores, and could improve sensitivity in the low score range. In the presence of high scores, no major diagnostic gain from an additional EBCTA versus CS alone could be observed.

Comparison of amlodipine or nifedipine treatment with developing congestive heart failure: effects on myocyte contractility

BACKGROUND

Past studies have suggested that amlodipine, a dihydropyridine L-type Ca(2+) channel antagonist, may exert useful effects in congestive heart failure (CHF). The present study examined the effects of amlodipine or nifedipine treatment in a model of developing CHF on left ventricular (LV) pump function and myocyte contractility.

METHODS AND RESULTS

Pigs (25 kg) were randomly assigned to 1 of 4 groups: 1) pacing-induced CHF (rapid atrial pacing at 240 bpm) for 3 weeks (n = 9), 2) concomitant Ca(2+) channel blockade with amlodipine (1.5 mg/kg/day) and rapid pacing (n = 7), 3) concomitant Ca(2+) channel blockade with nifedipine (0.7 mg/kg twice daily) and rapid pacing (n = 7), and 4) sham controls (n = 7). LV fractional shortening fell with pacing CHF from baseline values (17% +/- 1% v 42% +/- 1%, P <.05). With rapid pacing and concomitant amlodipine treatment, LV fractional shortening increased from pacing CHF values (24% +/- 1%, P <.05) but was unchanged with concomitant nifedipine treatment (20% +/- 2%, P =.2). LV myocyte velocity of shortening, as measured by high speed videomicroscopy, was reduced with pacing CHF compared with controls (42 +/- 2 microm/s v 87 +/- 9 microm/s, P <.05), and increased from pacing CHF values with amlodipine or nifedipine treatment (62 +/- 8 microm/s, 64 +/- 4 microm/s, respectively; P <.05). Inotropic response to extracellular Ca(2+) (8 mmol/L) was reduced with pacing CHF (94 +/- 5 microm/s v 160 +/- 15 microm/s, P <.05) and increased from CHF values with amlodipine or nifedipine treatment (132 +/- 14 microm/s and 133 +/- 7 microm/s, respectively, P <.05) CONCLUSIONS: These results suggest that the primary mechanism for the effects of amlodipine on myocyte contractility in developing CHF is because of direct Ca(2+) channel blockade.

Peroxisome proliferator-activated receptor (PPAR) gamma and retinoid X receptor (RXR) agonists have complementary effects on glucose and lipid metabolism in human skeletal muscle

AIMS/HYPOTHESIS

To determine the independent and potentially synergistic effects of agonists for PPAR gamma and RXR on glucose and lipid metabolism, as well as gene expression, in human skeletal muscle cell cultures.

METHODS

Fully differentiated myotubes from non-diabetic subjects and subjects with Type II (non-insulin-dependent) diabetes mellitus were chronically (2 days) treated with LG100268 (4 mumol/l), an RXR agonist, or troglitazone (4.6 mumol/l), a PPAR gamma agonist or both, to determine the effects on glucose uptake, activity of glycogen synthase and palmitate oxidation.

RESULTS

The combination of both agents increased glucose uptake (60 +/- 9% compared to control subjects) but not either agent alone (16 +/- 9 and 26 +/- 6% for LG100268 and troglitazone, p < 0.01, respectively). The agent LG100268 alone had little effect on the activity of glycogen synthase but the effect of troglitazone increased with LG100268 (p < 0.05). With chronic exposure, LG100268 upregulated palmitate oxidation (53 +/- 12% increase, p < 0.005), in a way similar to troglitazone (68 +/- 23%, p < 0.005). Synergism was observed when both agonists were combined (146 +/- 38%, p < 0.005 vs either agent alone). Treatment with either agent led to about a twofold increase in the expression of fatty acid transporter (FAT/CD36). Troglitazone upregulated PPAR gamma protein expression, whereas LG100268 had no effect. Furthermore, neither LG100268 nor troglitazone had any effect on the protein expression of RXR isoforms or PPAR alpha.

CONCLUSION/INTERPRETATION

Co-activation of PPAR gamma and RXR results in additive or synergistic effects on glucose and lipid metabolism in skeletal muscle, but unlike troglitazone, LG100268 does not alter expression of its own receptor.

A pilot study of rhuIL-11 treatment of refractory ITP

The objective of this research was to determine whether rhuIL-11 is an effective treatment in patients with refractory immune thrombocytopenic purpura (ITP). Platelet production is decreased in certain cases of refractory ITP. IL-11 stimulates megakaryocytopoiesis in vitro and was licensed for its clinical effects to ameliorate chemotherapy-induced thrombocytopenia. A pilot study was initiated, intending to enroll 12 patients with ITP. These patients were to receive rhuIL-11 (Neumega) at a dose of 50 microg/kg subcutaneously daily for 21 consecutive days and be observed afterward for 21 additional days. CBC with platelets were obtained twice weekly with visits and physical examinations weekly. The study was terminated after 7 patients were enrolled because of toxicity and lack of efficacy. All 7 patients had had ITP for >9 years and had failed splenectomy, intravenous gammaglobulin, corticosteroids, and a variety of other treatments. The patients at entry all had platelet counts <20,000/microl; 5 of 7 had counts <10,000/microl. The maximal median increase for any day of the study was 6,000/microl. No patient achieved a count of 30,000/microl, and only 3 patients achieved (once each) a platelet count >20,000/microl. Substantial toxicity was seen. The nadir hemoglobin decrease was a mean of 2 g/dl. rhuIL-11 was not effective at increasing the platelet count in any of these patients with refractory ITP. Toxicity was substantial. The lack of platelet response to rhuIL-11 in this study does not exclude the possibility of better effects at other doses and/or in less refractory patients.

Treatment with a growth hormone secretagogue in a model of developing heart failure: effects on ventricular and myocyte function

BACKGROUND

Exogenous administration of growth hormone (GH) and subsequently increased production of insulin-like growth factor-1 can influence left ventricular (LV) myocardial growth and geometry in the setting of congestive heart failure (CHF). This study determined the effects of an orally active GH secretagogue (GHS) treatment that causes a release of endogenous GH on LV function and myocyte contractility in a model of developing CHF.

METHODS AND RESULTS

Pigs were randomly assigned to the following treatment groups: (1) chronic rapid pacing at 240 bpm for 3 weeks (n=11); (2) chronic rapid pacing and GHS (CP-424,391 at 10 mg x kg(-1) x d(-1), n=9); and (3) sham controls (n=8). In the untreated pacing CHF group, LV fractional shortening was reduced (21+/-2% versus 47+/-2%) and peak wall stress increased (364+/-21 versus 141+/-5 g/cm(2)) from normal control values (P:<0.05). In the GHS group, LV fractional shortening was higher (29+/-2%) and LV peak wall stress lower (187+/-126 g/cm(2)) than untreated CHF values (P:<0.05). With GHS treatment, the ratio of LV mass to body weight increased by 44% from untreated values. Steady-state myocyte velocity of shortening was reduced with pacing CHF compared with controls (38+/-1 versus 78+/-1 microm/s, P:<0.05) and was increased from pacing CHF values with GHS treatment (55+/-7 microm/s, P:<0.05).

CONCLUSIONS

The improved LV pump function that occurred with GHS treatment in this model of CHF was most likely a result of favorable effects on LV myocardial remodeling and contractile processes. On the basis of these results, further studies are warranted to determine the potential role of GH secretagogues in the treatment of CHF.

A simple method of electroelution of individual protein bands from SDS polyacrylamide gels for direct study in cellular assays

A very simple and effective procedure which allows simultaneous electroelution of separated proteins from SDS polyacrylamide gel into small quantity of elution buffer is described. Elution parameters have been optimized for maximum possible recovery (50-60%). Protein fractions were collected in physiological buffer and an efficient removal of SDS have been obtained, thus fractions collected were suited for direct testing in cell cultures. Method was used to investigate human T-cell responses to purified secreted M tuberculosis H37Rv proteins. Eight low molecular weight (M.w. range 10 kD to 25 kD) culture filtrate proteins were purified in quantities, sufficient for immunological characterization. Lymphocyte proliferative responses and cytokine release pattern from tuberculosis patients, healthy contacts and healthy controls were studied on stimulation with purified culture filtrate proteins. Immunologically important M.tuberculosis proteins were identified by using this method. This approach should be applicable to the rapid identification and characterization of any interesting T cell antigen.

Bradykinin degradation and relation to myocyte contractility

BACKGROUND

Past studies have demonstrated that exogenous bradykinin (BK) causes vasodilation and increases coronary blood flow, effects that may be beneficial in the setting of cardiac disease states. An important pathway for BK degradation is through angiotensin-converting enzyme (ACE), which results in the formation of a degradative peptide, BK((1-7)). The goal of this study was to examine the effects of BK, BK((1-7)), and the potential modulation of BK by ACE inhibition on myocyte contractility.

METHODS AND RESULTS

Contractile function was examined in isolated adult porcine (n = 15) left ventricular (LV) myocyte preparations in the presence or absence of BK (10(-8) mol/L), BK((1-7)) (10(-8) mol/L), and with pretreatment by ACE inhibition (benazaprilat). Myocyte velocity of shortening fell by over 15% in the presence of BK and by 8% with BK((1-7)) (P <.05 vs basal). ACE inhibition blunted the negative effect of BK on myocyte velocity of shortening by over 60% (P <.05). Furthermore, robust ACE activity coupled with significant BK degradation was demonstrated in LV-isolated myocyte preparations, and BK proteolysis was influenced by ACE inhibition.

CONCLUSION

These results suggest that BK has a direct effect on LV myocyte contractility, and that this effect may be mediated by proteolysis of BK at the level of the LV myocyte sarcolemma.

Effects of combined angiotensin II and endothelin receptor blockade with developing heart failure: effects on left ventricular performance

BACKGROUND

The goal of this study was to determine the comparative effects of angiotensin II type 1 (AT(1)) receptor inhibition alone, endothelin-1 (ET) receptor blockade alone, and combined receptor blockade on left ventricular (LV) function, contractility, and neurohormonal system activity in a model of congestive heart failure (CHF).

METHODS AND RESULTS

Pigs were randomly assigned to each of 5 groups: (1) rapid atrial pacing (240 bpm) for 3 weeks (n=9), (2) concomitant AT(1) receptor blockade (valsartan, 3 mg/kg per day) and rapid pacing (n=8), (3) concomitant ET receptor blockade (bosentan, 50 mg/kg BID) and rapid pacing (n=8), (4) concomitant combined AT(1) and ET receptor inhibition and rapid pacing (n=8), and (5) sham-operated control (n=9). LV stroke volume was reduced from the control value after rapid pacing, was unchanged with either AT(1) or ET receptor blockade alone, but was improved with combination treatment. LV peak wall stress was reduced in both groups with ET receptor blockade compared with the rapid pacing group. Plasma norepinephrine levels were increased by >3-fold after rapid pacing, remained increased in the monotherapy groups, but were reduced after combination treatment. LV myocyte velocity of shortening was reduced after rapid pacing-induced CHF, remained reduced after AT(1) receptor blockade, increased after ET receptor blockade (compared with rapid pacing-induced CHF values), and returned to within control values after combined blockade.

CONCLUSIONS

Combined AT(1) and the ET receptor blockade in this model of CHF improved LV pump function, and contributory factors included the effects of LV loading conditions, neurohormonal system activity, and myocardial contractile performance. Thus, combined receptor blockade may provide a useful combinatorial therapeutic approach in CHF.

New bioactive aromatic compounds from Vismia guianensis

Five benzophenones, vismiaguianones A-E, and two benzocoumarins, vismiaguianins A and B were isolated from the CHCl3 extract of the roots of Vismia guianensis by bioassay-directed fractionation using the DNA strand-scission assay and KB cell line. Of the isolates obtained, vismiaguianone B exhibited DNA strand-scission activity, whereas vismiaguianones D and E and vismiaguianin A were found to be significantly cytotoxic.

A selective peroxisome proliferator-activated receptor-gamma (PPARgamma) modulator blocks adipocyte differentiation but stimulates glucose uptake in 3T3-L1 adipocytes

Peroxisome proliferator-activated receptor-gamma (PPARgamma) agonists such as the thiazolidinediones are insulin sensitizers used in the treatment of type 2 diabetes. These compounds induce adipogenesis in cell culture models and increase weight gain in rodents and humans. We have identified a novel PPARgamma ligand, LG100641, that does not activate PPARgamma but selectively and competitively blocks thiazolidinedione-induced PPARgamma activation and adipocyte conversion. It also antagonizes target gene activation as well as repression in agonist-treated 3T3-L1 adipocytes. This novel PPARgamma antagonist does not block adipocyte differentiation induced by a ligand for the retinoid X receptor (RXR), the heterodimeric partner for PPARgamma, or by a differentiation cocktail containing insulin, dexamethasone, and 1-methyl-3-isobutylxanthine. Surprisingly, LG100641, like the PPARgamma agonist rosiglitazone, increases glucose uptake in 3T3-L1 adipocytes. Such selective PPARgamma antagonists may help determine whether insulin sensitization by thiazolidinediones is mediated solely through PPARgamma activation, and whether there are PPARgamma-ligand-independent pathways for adipocyte differentiation. If selective PPARgamma modulators block adipogenesis in vivo, they may prevent obesity, lower insulin resistance, and delay the onset of type 2 diabetes.

Isolation, purification and immunological characterization of novel low molecular weight protein antigen CFP 6 from culture filtrate of M. tuberculosis

A novel immunogenic antigen, CFP 6 was purified from culture filtrate of M. tuberculosis by a preparatory 2-D electrophoresis method. The protein focused at pI of 4.0 during isoelectric focusing. Molecular weight of the purified protein by ES MS was found to be 11.61 kD. N-terminal amino acid sequence of CFP 6 could be aligned to the deduced amino acid sequence from ORF Rv3004 and was found to be a novel protein with 112 aa residues. Single N-terminal sequence showed that the purified protein was essentially free from contaminants and the amino acid analysis of the antigen was in good agreement with the DNA sequence deduced amino acid composition. Purified CFP 6 was studied for its ability to induce proliferative responses of peripheral blood lymphocytes from five categories of human subjects. These were: untreated, active pulmonary tuberculosis patients; patients after 2-3 months of chemotherapy; vaccinated professional contacts; vaccinated/nonvaccinated healthy controls. CFP 6 elicited high proliferative responses in healthy contacts and patients recovering from the disease. This protein also induced the release of a significantly high amount of IFN-gamma in cell culture supernatant of healthy contacts as compared to other categories of subjects. This protein was further evaluated and compared with PPD and total CS for its DTH inducing ability in guinea pigs immunised with BCG or M. tuberculosis H(37)Rv. CFP 6 elicited a powerful immune response in vitro and in vivo animal model, hence seems to be an immunologically important protein.

Mycobacterium w vaccine, a useful adjuvant to multidrug therapy in multibacillary leprosy: a report on hospital based immunotherapeutic clinical trials with a follow-up of 1-7 years after treatment

A vaccine based on autoclaved Mycobacterium w was administered, in addition to standard multidrug therapy (MDT), to 156 bacteriologically positive, lepromin negative multibacillary leprosy patients compared to a well matched control group of 145 patients with a similar type of disease who received a placebo injection in addition to MDT. The MDT was given for a minimum period of 2 years and continued until skin smear negativity, while the vaccine was given at 3-month intervals up to a maximum of eight doses. The fall in clinical scores and bacteriological indices was significantly more rapid in vaccinated patients, from 6 months onward until years 2 or 3 of therapy. However, no difference was observed in the fall in bacteriological index in the two groups from year 4 onwards. The number of LL and BL patients released from therapy (RFT) following attainment of skin smear negativity, after 24-29 months of treatment was 84/133 (63.1%) in vaccinated and 30/120 (25.0%) in the placebo group; the difference was highly statistically significant (P < 0.0001). In all, 90.2% patients (146/162) converted from lepromin negativity to positivity in the vaccine group, as against 37.9% (56/148) in the placebo group. The average duration of lepromin positivity maintained following eight doses of vaccine administered over 2 years was 3.016 years in the vaccine and 0.920 years in the placebo group. Histological upgrading after 2 years of treatment in the LL type was observed in 34/84 (40.5%) cases in the vaccine and 5/85 (5.9%) cases in the placebo group, the difference being statistically significant (P < 0.001). The incidence of type 1 reactions was significantly higher (30.5%) in the vaccine group than (19.7%) in the placebo group (P = 0.0413); the difference was mainly observed in LL type (P = 0.009). The incidence of type 2 reactions was similar (31.8 and 34.6%) in vaccine and placebo groups. The vaccine did not precipitate neuritis or impairments over and above that encountered with MDT alone. After 5 years of follow-up following RFT, no incidence of bacteriological or clinical relapses was observed in both groups.

Reactional states and neuritis in multibacillary leprosy patients following MDT with/without immunotherapy with Mycobacterium w antileprosy vaccine

A vaccine based on autoclaved Mycobacterium w was administered, in addition to standard multidrug therapy (MDT), to 157 untreated, bacteriologically positive, lepromin negative multibacillary leprosy patients, supported by a well matched control group of 147 patients with similar type of disease, who received a placebo injection in addition to MDT. The MDT was given for a minimum period of 2 years and continued until skin smear negativity, while the vaccine/placebo was given at 3-monthly intervals up to a maximum of eight doses. The incidence of type 2 reaction and neuritis during treatment and follow-up showed no statistically significant difference in the vaccine and placebo groups. The incidence of type 1 reaction (mild in most cases), however, was higher in the vaccine group (P = 0.041, relative risk ratio 1.79), considering LL, BL and BB leprosy types together, and considerably higher (P = 0.009) in LL type, probably because of confounding due to higher number of patients with previous history of reaction in this group. The occurrence of reactions and neuritis in terms of single or multiple episodes was similar in the vaccine and placebo groups. The association of neuritis and reactions, as well as their timing of occurrence (during MDT or follow-up), was also similar in the two groups, with more than 90% of occurrences taking place during MDT. The incidence of reversal reaction was significantly higher among the males in the vaccine group (34.5% versus 8.3%, P = 0.019). Patients with high initial BI (4.1-6.0) showed higher incidence of reactions (70.3%) as compared to those with medium (2.1-4.0) and low (0.3-2.0) BI where the reactions were observed with a frequency of 56.1% and 38.8%, respectively. However, unlike reactions, neuritis incidence did not seem to be affected by initial BI to the same extent in the vaccine group, with frequencies of 35.3%, 36.3% and 25.9% in the three mentioned BI ranges. Overall, the vaccine did not precipitate reactional states and neuritis over and above that observed with MDT alone.