Forced Uptake of Trivalent and Pentavalent Methylated and Inorganic Arsenic and Its Cyto-/genotoxicity in Fibroblasts and Hepatoma Cells

Mammals are able to convert inorganic arsenic to mono-, di-, and trimethylated metabolites. In previous studies we have shown that the trivalent organoarsenic compounds are more toxic than their inorganic counterparts and that the toxicity is associated with the cellular uptake of the arsenicals. In the present study, we investigated cyto-/genotoxic effects of the arsenic compounds arsenate [As(i)(V)], arsenite [As(i)(III)], monomethylarsonic acid [MMA(V)], monomethylarsonous acid [MMA(III)], dimethylarsinic acid [DMA(V)], dimethylarsinous acid [DMA(III)], and trimethylarsine oxide [TMAO(V)] after an extended exposure time (24 h) and compared the uptake capabilities of fibroblasts (CHO-9 cells: Chinese hamster ovary) used for genotoxicity studies, with those of hepatic cells (Hep G2: hepatoma cell-line). To find out whether the arsenic compounds are bound to membranes or if they are present in the cytosol, the amount of arsenic was measured in whole-cell extracts and in membrane-removed cell extracts by inductively coupled plasma-mass spectrometry (ICP-MS). In addition, we forced the cellular uptake of the arsenic compounds into CHO-9 cells by electroporation and measured the intracellular arsenic concentrations before and after this procedure. Our results show that organic and inorganic arsenicals are taken up to a higher degree by fibroblasts compared to hepatoma cells. The arsenic metabolite DMA(III) was the most membrane permeable species in both cell lines and induced strong genotoxic effects in CHO-9 cells after an exposure time of 24 h. The uptake of all other arsenic species was relatively low (<1% by Hep G2 and <4% by CHO cells), but was dose-dependent. Electroporation increased the intracellular arsenic levels as well as the number of induced MN in CHO-9 cells. With the exception of As(i)(III) and DMA(III) in CHO-9 cells, the tested arsenic compounds were not bound to cell membranes, but were present in the cytosol. This may indicate the existence of DMA(III)-specific exporter proteins as are known for As(i)(III). Our results indicate that the uptake capabilities of arsenic compounds are highly dependent upon the cell type. It may be hypothesized that the arsenic-induced genotoxic effects observed in fibroblasts are due to the high uptake of arsenicals into this cell type. This may explain the high susceptibility of skin fibroblasts to arsenic exposure.

Effect of lindane on hepatic and brain cytochrome P450s and influence of P450 modulation in lindane induced neurotoxicity

Oral administration of lindane (2.5, 5, 10 and 15 mg/kg, body weight) for 5 days was found to produce a dose-dependent increase in the activity of P450 dependent 7-ethoxyresorufin-O-deethylase (EROD), 7-pentoxyresorufin-O-dealkylase (PROD) and N-nitrosodimethylamine demethylase (NDMA-d) in rat brain and liver. A significant increase in the hepatic and brain P450 monooxygenases was also observed when the duration of exposure of low dose (2.5 mg/kg) of lindane was increased from 5 days to 15 or 21 days. As observed with different doses, the magnitude of induction in the activity of P450 monooxygenases was several fold higher in liver microsomes when compared with the brain. Western blotting studies have indicated that the increase in the P450 enzymes could be due to the increase in the expression of P450 1A1/1A2, 2B1/2B2 and 2E1 isoenzymes. In vitro studies using organic inhibitors specific for individual P450 isoenzymes and antibody inhibition experiments have further demonstrated that the increase in the activity of PROD, EROD and NDMA-d are due to the increase in the levels of P450 2B1/2B2, 1A1/1A2 and 2E1 isoenzymes, respectively. Induction studies have further shown that while pretreatment of 3-methylcholanthrene (MC), an inducer of P4501A1/1A2, did not produce any significant effect in the incidence of lindane induced convulsions, pretreatment with phenobarbital (PB), an inducer of P450 2B1/2B2 or ethanol, an inducer of P450 2E1 catalysed reactions, significantly increased the incidence of lindane induced convulsions. Similarly, when the P450-mediated metabolism of lindane was blocked by cobalt chloride incidence of convulsions was increased in animals treated with lindane indicating that lindane per se or its metabolites formed by PB or ethanol inducible P450 isoenzymes are involved in its neurobehavioral toxicity.

Cyclo-oxygenase 2 inhibitors: emerging roles in the gut

BACKGROUND AND AIMS

Discovery of an isoform of Cyclo-oxygenase (COX) 1, the inducible COX-2, has made it possible to avoid some side effects of non-specific COX inhibitors. The COX-2 gene is over-expressed in reflux oesophagitis, Barrett's oesophagus, gastric and colon cancer, familial adenomatous polyposis, pancreatic cancer, hepatocellular carcinoma, hepatotoxicity, cirrhosis, and inflammatory bowel disease, and specific COX-2 inhibitors have been tried experimentally and clinically and found effective.

METHODS

A Medline search was performed of English-language experimental studies and controlled clinical trials from January 1980 to January 2002, and relevant citations were noted.

RESULTS

Review of available literature shows that sulindac and COX-2 inhibitors are effective in preventing as well as regressing familial adenomatous polyposis. However, they have not been shown to prevent cancer in these patients. Studies evaluating NSAIDs and COX-2 inhibitors in carcinogen-induced and genetically manipulated animal models of various cancers have been promising especially in conditions such as Barrett's oesophagus, oesophageal and hepatocellular carcinoma and pancreatic cancer. COX-2 inhibitors may be of value in the treatment of reflux oesophagitis, pancreatitis and hepatitis, although carefully planned randomized controlled clinical trials demonstrating their efficacy need to be conducted. At present NSAIDs and COX-2 inhibitors cannot be recommended for average-risk individuals or for those with sporadic colorectal neoplasia (or other forms of cancers) as chemo-preventive agents.

CONCLUSION

COX-2 inhibitors may open up a new therapeutic era in which these drugs can be used for chemo-prophylaxis. However, COX-2 selective inhibitors retain renal adverse effects of the non-selective inhibitors and the concern regarding the pro-thrombotic potential of COX-2 inhibitors will limit their value as chemo-preventive agents.

An age- and sex-controlled matched pair analysis of T scores in ethnic Indians with hip fractures

OBJECTIVE

The first study to predict peritrochanteric fractures by the use of T scores amongst the Indian population was performed. This study aimed to assess the risk of fracture around the hip in peri-menopausal and postmenopausal women, and in men over the age of 35 years using dual energy X-ray absorptiometry, and to analyse whether the result, i.e. the T score, can predict an impending hip fracture.

METHODS

T scores of the unaffected hip in 30 patients with peritrochanteric fractures were determined, and matched pair analysis was done using a control group without fracture. All patients were from a single centre and were evaluated using the same scanner.

RESULTS

The mean T score of the 30 patients in the fracture group was -3.34 (range, -1.2 to -5.1; standard deviation [SD], 1.032), compared with the mean T score of the 30 control subjects which was -2.41 (range, 0.6 to -5.0; SD, 1.378). T scores of patients from the fracture group were significantly lower than those in the control group.

CONCLUSION

We infer that T scores are the best predictors for fracture risk. A score of -2.5 or lower effectively defines patients at risk and is useful for predicting fracture risk in the Indian population. In patients with osteoporosis, whether a fall precedes the fracture or the fracture precedes a fall may not be an issue of debate, but can serve as a basis for prevention of additional fractures by instituting appropriate measures in patients at risk.

Identification and characterization of murine Brunol4, a new member of the elav/bruno family

RNA-binding proteins are involved in post-transcriptional processes like mRNA stabilization, post-transcriptional modification, and transport and have been suggested to play an important role in developmental gene regulation. We report here the cloning and characterization of Brunol4, a novel mouse cDNA closely related to the elav-type family of genes encoding for RNA-binding proteins and a subfamily recently named after the bruno gene of Drosophila. Murine Brunol4 is localized near the centromere of chromosome 18. The cDNA sequence of Brunol4 is separated by 12 introns and the size of Brunol4 may be around 250 kb due to the large size of several introns. Brunol4 expression is detectable in the developing embryo and, later on becomes mainly restricted to cerebral structures, in particular the cerebellum where it persists in the adult organism. We predict a role of Brunol4 and the respective human homologue in differentiation and maintenance of neuronal structures.

Hypoglycemic and antihyperglycemic activity of Murraya koenigii leaves in diabetic rats

The commonly used spice curry patta (Murraya koenigii) is traditionally consumed by diabetics in southern part of India. Feeding of diet containing various doses of curry leaves (5, 10 and 15%) to normal rats for 7 days as well as mild diabetic (blood glucose levels >175 mg/dl induced by alloxan 35 mg/kg IP) and moderate diabetic rats (blood glucose levels >250 mg/dl induced by STZ 60 mg/kg IP) for 5 weeks showed varying hypoglycemic and anti-hyperglycemic effect. In normal rats, reduction in blood glucose was almost negligible (approximately 4% with 10 and 15% diet). In mild and moderate diabetic rats, feeding of 5, 10 and 15% diet caused a maximal reduction in blood sugar by 13.1, 16.3 and 21.4% (NS, P<0.05 and 0.005) and 3.2, 5.58, 8.21% (NS), respectively. The mechanism of action is further discussed in light of results of previous and the present study.

Infantile Alexander disease: a GFAP mutation in monozygotic twins and novel mutations in two other patients

Alexander disease (AD) is a rare disorder of cerebral white matter due to a dysfunction of astrocytes. The most common infantile form presents as a megalencephalic leukodystrophy. Recently, heterozygous de novo mutations in the glial fibrillary acidic protein gene (GFAP) have been demonstrated to be associated with AD. We report heterozygous mutations in GFAP in 5 patients, including a pair of monozygotic twins, with clinical and neuroradiological features of infantile AD. Novel mutations were detected affecting nucleotides 304 T --> C (L97 P) and 730 G --> C (R239 P) in two other patients. None of the parents of our patients carried the mutations stressing dominant de novo mutations as the cause of AD. The presence of an identical mutation 250 G --> A (R79 H) in both monozygotic twins with infantile AD points to the origin of these GFAP mutations in germ cells or very early postzygotic stages.

Medicinal plants of India with anti-diabetic potential

Since ancient times, plants have been an exemplary source of medicine. Ayurveda and other Indian literature mention the use of plants in treatment of various human ailments. India has about 45000 plant species and among them, several thousands have been claimed to possess medicinal properties. Research conducted in last few decades on plants mentioned in ancient literature or used traditionally for diabetes have shown anti-diabetic property. The present paper reviews 45 such plants and their products (active, natural principles and crude extracts) that have been mentioned/used in the Indian traditional system of medicine and have shown experimental or clinical anti-diabetic activity. Indian plants which are most effective and the most commonly studied in relation to diabetes and their complications are: Allium cepa, Allium sativum, Aloe vera, Cajanus cajan, Coccinia indica, Caesalpinia bonducella, Ficus bengalenesis, Gymnema sylvestre, Momordica charantia, Ocimum sanctum, Pterocarpus marsupium, Swertia chirayita, Syzigium cumini, Tinospora cordifolia and Trigonella foenum graecum. Among these we have evaluated M. charantia, Eugenia jambolana, Mucuna pruriens, T. cordifolia, T. foenum graecum, O. sanctum, P. marsupium, Murraya koeingii and Brassica juncea. All plants have shown varying degree of hypoglycemic and anti-hyperglycemic activity.

Purification, crystallization and preliminary X-ray diffraction studies of disintegrin (schistatin) from saw-scaled viper (Echis carinatus)

This is the first report of crystallographic data on a disintegrin molecule from any source. The heterodimeric disintegrin with a molecular weight of 14 kDa from Echis carinatus venom is a potent antagonist of alpha4 integrins. The intact disintegrin, containing two subunits A and B, was isolated and purified using affinity and ion-exchange columns. It has been crystallized using 1.6 M ammonium sulfate as a precipitating agent. The crystals grew to dimensions of 0.25 x 0.20 x 0.20 mm and diffracted to 2.5 A resolution. The crystals belong to space group I4(1)22, with unit-cell parameters a = b = 91.7, c = 55.1 A. Assuming a molecular weight of 14 kDa, a V(M) of 2.1 A(3) Da(-1) is obtained for one molecule of disintegrin in the asymmetric unit.

Comparison of two blood collection techniques for measles antibody detection in children

BACKGROUND & OBJECTIVES

Though several seroprevalence and seroconversion studies have been conducted for measles using the filter paper haemagglutination inhibition (FPHAI), very few studies have compared the conventional serum HAI with the FPHAI. The present study was aimed at the evaluation of whole blood samples on filter paper as an alternative to serum specimens for detection of antibodies to measles virus.

METHODS

Serum and whole blood samples soaked on filter paper were collected from 165 randomly selected healthy children in the age groups of 1-2 yr. HAI test was performed on both sets of samples and the results compared.

RESULTS

Ninety samples that gave a titre of 8 or more by serum HAI also had titres of > or = 8 by FPHAI showing 100 per cent agreement between the two assays. Seventeen samples that had a serum HAI titre of 2 and 4 were missed by FPHAI due to the starting dilution of 8 of the latter. However, FPHAI gave no false positive results compared with serum HAI.

INTERPRETATION & CONCLUSION

Collection of the FP samples by finger prick is more acceptable and requires less expertise than venepuncture. Thus, in spite of the small percentage of missed cases by the filter paper method, this technique of sampling was found to be a convenient and reliable alternative to venepuncture, for detection of measles virus antibody especially in large scale seroepidemiological studies.

Anthelmintics: a review

Helminths infect 25% of the world's population. In the last 50 years specific, safe and effective anthelminitic drug therapy for various parasitic infestations have been developed. The population of the developing countries across the globe suffers not only as a direct result of these infections but due also to co-morbidity such as anemia, malnutrition and reduced immunity status. Earlier anthelmintic drugs suffered from serious drawbacks such as hepatotoxicity and required specific preparation of the patient before treatment such as 12-hour fasting and pre-post purging caused considerable inconvenience to the patient. However, successive discoveries were born out of rationale approach that contributed to the effective, more specific and more easily tolerated drugs i.e. benzimidazoles, piperazine derivatives, avermectins, pyrazinoquinoline, etc. The present approach is to identify the causative parasite on the basis of stool examination and as a result of this approach, different drugs are prescribed for different parasitic infections. Examples include thiabendazole for cutaneous larva migrans, mebendazole for ascariasis, trichiuriasis and hookworm, albendazole for inoperable cases of cystic hydatid disease, DEC for Toxocara induced visceral larva migrans and loiasis, ivermectin for onchocerciasis, praziquantel for schistosomiasis and niridazole for Dracunculus medinensis. The cure rates with these drugs is also high e.g. thiabendazole produces a cure-rate of 98% in cutaneous larva migrans while mebendazole gives cure rate of 76-95% in ascariasis, trichiuriasis and hookworm infestations. A cure rate of 96% is produced by praziquantel in schistosomiasis. Most of these drugs have broad-spectrum anthelmentic effect. The present review aims at evaluating the currently available anthelmintics with respect to their efficacy and adverse effects. Steps to prevent impending helminthic drug resistance are also discussed.

A novel 40 kDa protein from goat mammary secretions: purification, crystallization and preliminary X-ray diffraction studies

A novel 40 kDa protein has been purified from dry secretions of the mammary gland of goats. The first 15 N-terminal residues were sequenced and showed a sequence identity of 30% to a novel 39 kDa whey protein from bovine mammary secretions. The protein was crystallized by the microdialysis method. Protein was dissolved to a concentration of 40 mg ml(-1) in 0.025 M Tris-HCl pH 8.0 and equilibrated with the same buffer containing 19%(v/v) ethanol. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 66.1, b = 107.8, c = 63.2 A and one molecule per asymmetric unit. Intensity data were collected to 2.9 A resolution, with a completeness of 95%. Since no similar model is available in the protein structure database, heavy-atom derivatives have been prepared and three-dimensional structure determination using the isomorphous replacement method is in progress.

Differentiation of atypical moles (dysplastic nevi) from early melanomas by dermoscopy

Several conventional and new dermoscopic criteria are highly specific for diagnosing early melanomas. Until the reliability of the dermoscopic scoring systems has been validated, the presence of any combination of these specific features should elevate the index of suspicion for melanoma and prompt a biopsy to avoid missing this cancer.

Juvenile rheumatoid arthritis with amyloid goiter: report of a case with review of the literature

Clinically significant enlargement of the thyroid owing to amyloid deposition is a rare occurrence. A 23-yr-old female, a case of juvenile rheumatoid arthritis, developed rapidly increasing thyromegaly during the course of her illness with complaints of dyspnea and dysphagia. Thyroid function tests were within normal limits. Fine-needle aspiration cytology proved inconclusive. Total thyroidectomy was done for symptomatic relief with a preoperative clinical impression of malignancy. Histopathologic findings were consistent with amyloid goiter. The findings of this case are presented, to emphasize the difficulties in making a definite preoperative diagnosis, along with a brief review of the literature.

Teaching residents evidence-based medicine skills: a controlled trial of effectiveness and assessment of durability

OBJECTIVES

To measure the effectiveness of an educational intervention designed to teach residents four essential evidence-based medicine (EBM) skills: question formulation, literature searching, understanding quantitative outcomes, and critical appraisal.

DESIGN

Firm-based, controlled trial.

SETTING

Urban public hospital.

PARTICIPANTS

Fifty-five first-year internal medicine residents: 18 in the experimental group and 37 in the control group.

INTERVENTION

An EBM course, taught 2 hours per week for 7 consecutive weeks by senior faculty and chief residents focusing on the four essential EBM skills.

MEASUREMENTS AND MAIN RESULTS

The main outcome measure was performance on an EBM skills test that was administered four times over 11 months: at baseline and at three time points postcourse. Postcourse test 1 assessed the effectiveness of the intervention in the experimental group (primary outcome]; postcourse test 2 assessed the control group after it crossed over to receive the intervention; and postcourse test 3 assessed durability. Baseline EBM skills were similar in the two groups. After receiving the EBM course, the experimental group achieved significantly higher postcourse test scores (adjusted mean difference, 21%; 95% confidence interval, 13% to 28%; P < .001). Postcourse improvements were noted in three of the four EBM skill domains (formulating questions, searching, and quantitative understanding [P < .005 for all], but not in critical appraisal skills [P = .4]). After crossing over to receive the educational intervention, the control group achieved similar improvements. Both groups sustained these improvements over 6 to 9 months of follow-up.

CONCLUSIONS

A brief structured educational intervention produced substantial and durable improvements in residents' cognitive and technical EBM skills.

Nephron-sparing surgery in a case of giant renal hydatid cyst

We report a case of a centrally located giant renal hydatid cyst managed successfully by excision of the cyst alone and preserving the renal parenchyma after clamping the main renal artery. Follow-up IVP showed good function.