Crystal structure of Jararacussin-I: the highly negatively charged catalytic interface contributes to macromolecular selectivity in snake venom thrombin-like enzymes

Snake venom serine proteinases (SVSPs) are hemostatically active toxins that perturb the maintenance and regulation of both the blood coagulation cascade and fibrinolytic feedback system at specific points, and hence, are widely used as tools in pharmacological and clinical diagnosis. The crystal structure of a thrombin-like enzyme (TLE) from Bothrops jararacussu venom (Jararacussin-I) was determined at 2.48 Å resolution. This is the first crystal structure of a TLE and allows structural comparisons with both the Agkistrodon contortrix contortrix Protein C Activator and the Trimeresurus stejnegeri plasminogen activator. Despite the highly conserved overall fold, significant differences in the amino acid compositions and three-dimensional conformations of the loops surrounding the active site significantly alter the molecular topography and charge distribution profile of the catalytic interface. In contrast to other SVSPs, the catalytic interface of Jararacussin-I is highly negatively charged, which contributes to its unique macromolecular selectivity.

Structural insights into selectivity and cofactor binding in snake venom L-amino acid oxidases

L-Amino acid oxidases (LAAOs) are flavoenzymes that catalytically deaminate L-amino acids to corresponding α-keto acids with the concomitant production of ammonia (NH(3)) and hydrogen peroxide (H(2)O(2)). Particularly, snake venom LAAOs have been attracted much attention due to their diverse clinical and biological effects, interfering on human coagulation factors and being cytotoxic against some pathogenic bacteria and Leishmania ssp. In this work, a new LAAO from Bothrops jararacussu venom (BjsuLAAO) was purified, functionally characterized and its structure determined by X-ray crystallography at 3.1 Å resolution. BjsuLAAO showed high catalytic specificity for aromatic and aliphatic large side-chain amino acids. Comparative structural analysis with prokaryotic LAAOs, which exhibit low specificity, indicates the importance of the active-site volume in modulating enzyme selectivity. Surprisingly, the flavin adenine dinucleotide (FAD) cofactor was found in a different orientation canonically described for both prokaryotic and eukaryotic LAAOs. In this new conformational state, the adenosyl group is flipped towards the 62-71 loop, being stabilized by several hydrogen-bond interactions, which is equally stable to the classical binding mode.

Sero-epidemiology of peste des petits ruminants (PPR) in Pakistan

A sero survey was conducted during 2005-2006 to estimate the sero prevalence of PPR in the small ruminant population of Pakistan. A total of 2798 samples were collected including goats (1979) and sheep (819) from villages in 27 randomly selected districts. These were tested by cELISA for PPRV and true prevalence estimates were calculated by Rogan and Gladen estimator. Overall, 1273 (45.5%) were found positive; 980 (49.5%) of 1979 samples from goats and 293 (35.8%) of 819 serum samples from sheep were positive. The true sero-prevalence of PPR was estimated to be 48.5% (95% CI, 46.6-50.3), and 52.9% (95% CI, 50.7-55.1) and 37.7 (95% CI, 34.4-41.0) for goats and sheep, respectively. PPR virus is widely distributed all across Pakistan and has become an endemic infection of small ruminants. Since it is one of the leading causes of morbidity and mortality in small ruminants, it poses a serious threat to food security and the rural economy in Pakistan.

Experimental observation of Loschmidt time reversal of a quantum chaotic system

We have performed an experiment to demonstrate the approximate time reversal of a "chaotic" time evolution of atomic de Broglie waves. We use ultracold atoms from a Bose-Einstein condensate in a quantum δ-kicked rotor experiment, and show that an initial state can be approximately re-created even after a period of "chaotic" evolution (a number of kicks). As this mechanism only works for a very narrow range of momenta, the net effect is a narrowing of the momentum distribution after the kick sequence.

The epidemiology of peste des petits ruminants in Pakistan

Peste des petits ruminants (PPR) is an acute and highly contagious viral disease of small ruminants, which is newly emerging in Pakistan. Information provided by participatory disease surveillance teams was used to develop a database for PPR outbreaks in Pakistan. Twenty-four villages were selected throughout the country and field investigations were conducted in each village to study the dynamics of the disease. In each area, flocks with a history of PPR were identified and serological sampling was conducted. Some 1,463 small ruminants (sheep and goats) were sampled and 1,096 tested positive for the presence of antibodies against PPR. These results clearly indicate that PPR is prevalent throughout Pakistan.

Visual and computer software-aided estimates of Dupuytren's contractures: correlation with clinical goniometric measurements

INTRODUCTION

Corrective surgery for Dupuytren's disease represents a significant proportion of a hand surgeon's workload. The decision to go ahead with surgery and the success of surgery requires measuring the degree of contracture of the diseased finger(s). This is performed in clinic with a goniometer, pre- and postoperatively. Monitoring the recurrence of the contracture can inform on surgical outcome, research and audit.

PATIENTS AND METHODS

We compared visual and computer software-aided estimation of Dupuytren's contractures to clinical goniometric measurements in 60 patients with Dupuytren's disease. Patients' hands were digitally photographed. There were 76 contracted finger joints--70 proximal interphalangeal joints and six distal interphalangeal joints. The degrees of contracture of these images were visually assessed by six orthopaedic staff of differing seniority and re-assessed with computer software.

RESULTS

Across assessors, the Pearson correlation between the goniometric measurements and the visual estimations was 0.83 and this significantly improved to 0.88 with computer software. Reliability with intra-class correlations achieved 0.78 and 0.92 for the visual and computer-aided estimations, respectively, and with test-retest analysis, 0.92 for visual estimation and 0.95 for computer-aided measurements.

CONCLUSIONS

Visual estimations of Dupuytren's contractures correlate well with actual clinical goniometric measurements and improve further if measured with computer software. Digital images permit monitoring of contracture after surgery and may facilitate research into disease progression and auditing of surgical technique.

Migration is associated with lower total, but not free testosterone levels in South Asian men

OBJECTIVE

Serum testosterone measurement is an integral part of the endocrine assessment of men. Little is known about its variation in relation to migration. We examined within a South Asian group the effect of migration to the UK on androgen levels.

DESIGN

Circulating testosterone and SHBG concentrations were measured in 97 Gujarati men resident in India and in 79 men from the same villages of origin living in Birmingham, UK. Free testosterone was calculated by Vermeulen's method. Insulin sensitivity (HOMA-S) was determined from paired fasting plasma intact insulin and glucose values.

RESULTS

Circulating testosterone was significantly lower in UK Gujarati men (17.2 nmol/l [15.7-18.7]) vs. Indian Gujarati men (21.7 [20.0-23.5]) (P = 0.0002) (age-adjusted median [95% CI]). There was no difference by migration status in circulating free testosterone. Sex hormone binding globulin (SHBG) levels were lower in UK migrants (16.8 nmol/l [15.5-18.1]) than in nonmigrants (21.9 nmol/l [20.5-23.3]) (P < 0.0001). Testosterone level correlated positively with insulin sensitivity (HOMA-S) (rho 0.16, P = 0.04). In multivariate analysis, total testosterone was independently and positively associated with logSHBG (normalized beta (beta) = 0.29, P = 0.002) and independently and negatively with waist circumference (beta = -0.19, P = 0.04), in a model also including height, age, migration status, leptin and fasting insulin.

CONCLUSION

Lower circulating testosterone in UK Gujarati men and its association with markers of insulin sensitivity suggest a profound influence of body composition change with migration on testosterone levels. The lower SHBG in this group restores parity in free testosterone. Account should be taken of SHBG in interpreting testosterone levels in men, as well as in women.

Urticaria and large cell undifferentiated carcinoma of lung

The association of urticaria with internal cancer is known mostly with lymphoreticular system malignancies. Rarely, it occurs with cancer of lung, mostly with adenocarcinoma or small cell carcinoma. We report a unique occurrence of urticaria on a patient who suffered from large cell undifferentiated carcinoma of lung. Only the treatment for malignancy relieved the patient from his long standing cutaneous manifestation.

Suppression of a sialyltransferase by antisense DNA reduces invasiveness of human colon cancer cells in vitro

Transfer of terminal alpha 2,6-linked sialic acids to N-glycans is catalyzed by beta-galactoside alpha 2,6-sialyltransferase (ST6Gal I). Expression of ST6Gal I and its products is reportedly increased in colon cancers. To investigate directly the functional effects of ST6Gal I expression, human colon cancer (HT29) cells were transfected with specific antisense DNA. ST6Gal I mRNA and protein were virtually undetectable in six strains of transfected HT29 cells. ST6Gal activity was reduced to 14% of control (P<0.005) in transfected cells. Expression of terminal alpha 2,6- and alpha 2,3-linked sialic acids, and unmasked N-acetyllactosamine oligosaccharides, respectively, was assessed using flow cytometry and fluoresceinated Sambucus nigra, Maackia amurensis and Erythrina cristagalli lectins. Results indicated a major reduction in expression of alpha 2,6-linked sialic acids and counterbalancing increase in unmasked N-acetyllactosamines in antisense DNA-transfected cells, without altered expression of alpha 2,3-linked sialic acids or ganglioside profiles. The ability of transfected cells to form colonies in soft agar and to invade extracellular matrix material (Matrigel), respectively, in vitro was reduced by approx. 98% (P<0.0001) and more than 3-fold (P<0.005) compared to parental HT29 cells. These results indicate that N-glycans bearing terminal alpha 2,6-linked sialic acids may enhance the invasive potential of colon cancer cells.

Pancreatic pseudocyst with biliary fistula: treatment with endoscopic internal drainage

Surgical drainage is the standard treatment for pancreatic pseudocysts and their complications. However, acute symptomatic pancreatic pseudocysts are amenable to endoscopic internal drainage in select cases. We report a case of pancreatic pseudocyst with biliary fistula resulting from a recurrent pseudocyst treated with endoscopic stent drainage.

Downregulation of a human colonic sialyltransferase by a secondary bile acid and a phorbol ester

Fecal constituents such as bile acids and increased sialylation of membrane glycoproteins by alpha-2,6-sialyltransferase (HST6N-1) may contribute to colorectal tumorigenesis. We hypothesized that bile acids and phorbol ester [12-O-tetradecanoylphorbol-13-acetate (TPA)] would upregulate HST6N-1 in colonic cells. However, deoxycholate (DOC) (300 mumol/l), a secondary bile acid, and TPA (20 ng/ml) decreased expression of an approximately 100-kDa glycoprotein bearing alpha-2,6-linked sialic acid in a colon cancer cell line (T84) in vitro. HST6N-1 mRNA levels were reduced approximately 80% by treatment (< or = 24 h) with DOC or TPA but not by cholate, a primary bile acid. Treatment (24 h) with DOC or TPA decreased activity of this enzyme to 30% and 13% of control, respectively. These effects of DOC and TPA were transcriptional and were mediated by Ca2+ and protein kinase C, respectively. Thus DOC and TPA both downregulated, and did not upregulate, alpha-2,6-sialyltransferase expression in vitro, but by different transduction pathways. As colorectal tumors grow, their progressive removal from the fecal milieu that normally downregulates this enzyme may favor invasion and metastasis.

Changes in physical and chemical constituents of crab meat during storage at refrigerator temperature (7+/-2 degrees C)

The present study was initiated to determine the deteriorative changes occurred in the nutritive quality of crabmeat during storage at refrigerator temperature (7+/-2) for the period of one week. The parameters studied for the assessment of quality are pH, water, total protein and salt soluble protein, TMA-N, TVB-N content. The results indicate a significant increase (p < or = 0.001) in pH, water, TMA. TVB while total protein salt soluble protein, and total lipid contents were significantly decreased (p < or = 0.001) as compared to fresh tissue. Our finding recommended that the quality of crabmeat is acceptable upto one day of storage at refrigerator temperature after that it becomes deteriorated.

A study on comparative efficacyof hypolipidemic drugs

A study was carried out on the comparative efficacy of Lopid, Mevacor, Bezalip and Lasona in sixteen hyperlipidemic subjects. All the subjects were on Lopid at least for the last 15 days. Lopid therapy was discontinued after determining blood lipid profile of the subjects on day zero (day of 1st contact). The subjects were divided into three groups and after a washout period of 15 days, they were given three different drugs for the next 15 days. Subjects in group a (6), b (5) and c (5) received Mevacor, Bezalip and lasona respectively. In the present study mevacor was found to be the most potent hypolipidemic drug in lowering blood cholesterol and Low density lipoprotein (LDL) while lopid was most effective in keeping blood Triglycerides (TG) and High density lipoproteins (HDL) level within the desired limits. Bezalip and Lasona were also sufficiently effective in changing blood lipid profile, but lasona showed a negligible effect on HDL rise as compared with Bezalip or any other drug used in this study.

Stability of fecapentaene-12 and its carcinogenicity in F-344 rats

Carcinogenicity studies of the fecal mutagen fecapentaene-12 (FP-12) have been hampered because of its apparent instability. We report here that: (i) contrary to the popular belief, FP-12 is quite stable, particularly at micromolar to nanomolar concentration; and (ii) its characteristic spectrophotometric absorbance spectrum is a function of the solvent or vehicle. Using synchronous fluorescence spectrophotometry (SFS), we have determined that at delta lambda 36.5 nm FP-12 gives a characteristic single emission peak between 413 and 423 nm, allowing us to identify FP-12 in DNA when reacted in vitro. We also report an increased incidence (statistically not significant) of fibrosarcomas and mammary carcinomas in male F-344 rats following intrarectal instillation of FP-12. In the in vitro human colon explant model, direct addition of FP-12 results in alteration in mucin histochemical changes typical of precancer and cancer. Our results support the contention that FP-12 is a naturally occurring carcinogen and may be responsible for human cancer(s).

Dose-dependent inhibition of large intestinal cancer by inositol hexaphosphate in F344 rats

We have previously reported that inositol hexaphosphate (InsP6) inhibits mitosis and large intestinal cancer (LIC) in F344 rats and CD1 mice when given as 1 or 2% solution in drinking water at the unadjusted pH of 11.3. The purpose of this study was to determine whether InsP6 (i) shows a dose-response inhibition of LIC, and (ii) retains its anti-neoplastic effect at physiological pH. Since InsP6 is known to be a chelator of divalent cations, in preparation for putative clinical trials in humans, we also looked at the mineral bioavailability. F344 rats were fed 0.1% (pH 10.8), 1% (pH 11.3) and 1% (pH 7.4) Na-InsP6 in drinking water. Two weeks following the beginning of InsP6 supplementation, rats were given six injections of azoxymethane (AOM) at a dose of 8 mg/kg body wt/week and were killed 30 weeks following the last injection. Compared to the untreated control rats injected with AOM, 1% InsP6 (pH 11.3) reduces tumor prevalence by 52.2% (P less than 0.01), tumor frequency by 55.8% (P = 0.001) and tumor size by 62.3% (P = 0.001); 0.1% InsP6 showed a lesser reduction in tumor prevalence (21%) but a greater reduction in tumor size 71% (P = 0.001). While there was no significant difference in tumor prevalence and frequency between the two pH groups, the tumor size following 1% InsP6 (pH 7.4) was the smallest (65% smaller than those of pH 11.3, P less than 0.005). There was no significant difference in the serum Mg2+, Ca2+, Fe2+ and Zn2+ level between control rats and those treated with 1% InsP6. We therefore demonstrate that InsP6 (i) is consistently anti-neoplastic for LIC in a dose-dependent manner, (ii) retains its anti-neoplastic activity at physiological pH and (iii) has no demonstrable toxic effect on long-term administration as evident by body wt data and serum mineral levels.

Adenocarcinoma of the ileostomy: the latent risk of cancer after colectomy for ulcerative colitis and familial polyposis

A case of a primary adenocarcinoma of an ileostomy is reported along with 15 other cases collected from the literature. These rare tumors are seen on the average 24 years after colectomy with ileostomy and in all cases are associated with a past history of ulcerative colitis or familial polyposis. Most of the reported cases of these tumors have appeared in the literature within the past 5 years, suggesting that there is a rising incidence of this disease corresponding to completion of a biologic latency period that began when the Brooke ileostomy was introduced for ulcerative colitis in 1951. In our case a mucinous adenocarcinoma occurred at the ileostomy site 34 years after colectomy. Adjacent to the tumor was mucosa showing colonic metaplasia and focal dysplasia. Subsequent biopsy specimens of the revised stoma showed inflammatory lesions morphologically suggestive of inflammatory (pseudo) polyps. The clinical and morphologic features in this case suggest that there is transition from ileal mucosa to colonic mucosa to colonic dysplasia to adenocarcinoma. Annual evaluation of the ileostomy for colonic metaplasia, inflammatory lesions consistent with ulcerative colitis and dysplasia, is recommended. In the presence of dysplasia, stomal revision is advised. Wide local excision is advised for adenocarcinoma.

Colonic metaplasia of ileostomies. Biological significance for ulcerative colitis patients following total colectomy

Two patients who had undergone proctocolectomy for ulcerative colitis developed lesions in their ileal stoma that appeared to be inflammatory polyps morphologically similar to those encountered in the large intestine of ulcerative colitis patients. One of these patients eventually developed mucinous adenocarcinoma in the ileal stoma. The ileal mucosa adjacent to the neoplasm had morphologic features of large-bowel mucosa and was richly populated by sulfomucin-containing goblet cells, which are characteristic of large-bowel mucosa. Sulfomucin-containing goblet cells were also found in the inflammatory lesions biopsied from the ileal stomas of both patients, as well as from the adenocarcinoma found in one patient. These findings support the hypothesis that colonic metaplasia can occur in ileal stomas of ulcerative colitis patients. Furthermore, the metaplastic colonic tissue is the site of origin of lesions typically found in ulcerative colitis. Colonic metaplasia occurring in ileal stoma should be recognized by pathologists as a clinical entity. When colonic metaplasia is identified in the ileal stoma of an ulcerative colitis patient, biopsy surveillance of stomal mucosa is recommended.

Inositol-phosphate-induced enhancement of natural killer cell activity correlates with tumor suppression

In recent studies, we have demonstrated that inositol hexaphosphate (InsP6) inhibits experimental colon carcinogenesis. Since natural killer (NK) cells are involved in tumor cell destruction, we investigated the effect of InsP6 on murine NK cell activity. We show that; (i) 1,2-dimethylhydrazine (DMH), a colon carcinogen, depresses NK activity; (ii) in vivo treatment of mice with InsP6 enhances baseline NK activity and reverses DMH-induced depressed NK activity with an inverse correlation (r = -0.9811) with tumor incidence, (iii) short-term in vitro treatment of spleen cells and NK-enriched fraction with InsP6 also enhances NK cytotoxicity in a dose-dependent manner, (iv) inositol potentiates the action of InsP6. Our data suggest yet another important role of inositol phosphates in the regulation of cellular activity.

Inositol and inositol hexaphosphate suppress cell proliferation and tumor formation in CD-1 mice

In previous studies, we have shown that inositol hexaphosphate (InsP6), a constituent of cereal diet, inhibited azoxymethane-induced experimental large intestinal cancer (LIC) in Fischer 344 rats. We now report a similar antineoplastic action of InsP6 in CD-1 mice injected with 1,2-dimethylhydrazine (DMH). We had hypothesized that InsP6 may bring about this effect by undergoing dephosphorylation to lower phosphorylated forms; the ready availability of Ins, to react with phosphates, may increase the total amount of the lower phosphorylated Ins and potentiate the action of InsP6. LIC induced by DMH (15 mg/kg/week x 13) in mice given a mixture of 1% InsP6 + 1% Ins show a significant reduction (P less than 0.005) in LIC prevalence over InsP6 treatment. Surprisingly, Ins, an in vitro growth promoting agent also caused a significant (P less than 0.001) suppression of LIC. InsP6 +/- Ins also showed a concomitant reduction in the mitotic rate in the non-neoplastic epithelium. Body weight data did not suggest any overt toxic effect of long-term administration of InsP6, Ins or InsP6 + Ins. Since InsP6 is antineoplastic in two species of experimental animals, it should, in combination with Ins, be considered in our strategies for prevention of large intestinal cancer.

Inositol hexaphosphate inhibits large intestinal cancer in F344 rats 5 months after induction by azoxymethane

A treatment regimen of 2% Na-InsP6 in drinking water was effective in significantly reducing large intestinal cancer in F344 rats even when the treatment was begun 5 months after carcinogenic induction with azoxymethane (AOM 8 mg/kg/wk X 6). Compared to untreated (AOM-only) rats, animals on InsP6 had 27% fewer tumors (P less than 0.02). The tumors were approximately two-thirds smaller in size (P less than 0.01) and percentage mitotic rate in the non-neoplastic epithelium was less than half (1.0 +/- 0.1, compared to 2.3 +/- 0.2 of AOM-only animals, significant at P less than 0.001). We postulate that InsP6 may exert its antineoplastic effect by way of regulating cellular proliferation even after effective carcinogenic stimuli and thus may be an important candidate for chemointervention.

Suppression of large intestinal cancer in F344 rats by inositol hexaphosphate

Epidemiological data demonstrate correlations between dietary factors and the incidence of large intestinal cancer (LIC). Certain high-fiber diets are associated with a lower risk of LIC; these high-fiber diets are also rich in inositol hexaphosphate (IP6 or phytic acid). In a pilot study, we have used F344 rats to investigate the effect of sodium inositol hexaphosphate (Na-IP6) prior to (experiment I) and following injections of the carcinogen azoxymethane (AOM) (experiment II). In experiment I, rats started on 1% Na-IP6 in drinking water 1 week prior to the carcinogen treatment showed a 34.7% decrease (P less than 0.01) in LIC compared to control carcinogen treatment group. A similar reduction in the incidence of LIC was also observed in experiment II, wherein Na-IP6 supplementation was started 2 weeks following the last dose of the carcinogen. Comparison of the incidence of mitosis in the colonic crypts of the animals in different groups show that animals on AOM + IP6 demonstrate a significantly lower (P less than 0.001) mitotic rate than those receiving AOM only. Pilot studies of free radical generation demonstrate a reduction in .OH radical formation by Na-IP6. Further studies to expand this pilot data and to understand the mechanism of IP6 mediated LIC suppression are needed for it may have significance in our strategies for LIC control.

Fecal mutagen fecapentaene-12 damages mammalian colon epithelial DNA

Fecapentaenes are fecal mutagens that are naturally produced in the human colon and have been shown to be highly mutagenic in the Ames assay system. However to date no studies have been reported regarding the effects of fecapentaene in the target epithelium. In vivo studies with fecapentaene-12 (FP-12) using Fischer 344 rats in our laboratory indicate that a concentration of 10(-6) M FP-12 is capable of inducing a 2.7-fold increase (P less than 0.001) in [3H]-thymidine incorporation into DNA. Autoradiographic studies demonstrate a similar (2.6-fold) increase in the labelling index but an 8.8-fold reduction in the mitotic rate in colonic epithelial cells. Results of DNA single-strand breakage measurements show that in vivo treatment with FP-12 at concentrations of 1 microM introduces a 16-fold increase (P less than 0.001) in the number of alkali-labile sites over controls. Similar studies in in vitro assays indicate a linear trend in the number of alkali-labile sites over a range of concentrations varying from 1 nM to 1 microM. These findings indicate that the fecal mutagen FP-12 induces damage in situ to nucleic acids and thus may play a role in neoplastic transformation of the colon.