Adenosine affects the calcium dynamics of rat portal vein

1. The present study was carried out to characterize the effect of adenosine on calcium dynamics in the rat portal vein. Isolated portal vein of male albino rats was used as the experimental model as it exhibits autorhythmicity. 2. Adenosine and its analogues 2-CAD, N6-CHA and NECA were used to characterize the type of adenosine receptor involved and 2-CAD was used along with adenosine throughout the other part of study to characterize the effect of adenosine on Ca2+ dynamics. Adenosine and its analogues were found to inhibit the spontaneous contractions of rat portal vein in a concentration-related manner. The order of potency was NECA > 2-CAD > N6-CHA > adenosine. Incubation of the tissue with CGS-15943A, an adenosine receptor antagonist, had a per se enhancing effect on autorhythmicity. Adenosine and 2-CAD failed to reverse the contractile response produced by hypertonic KCl (80 or 30 mM). Whereas adenosine and 2-CAD effectively relaxed the tissues contracted with phenylephrine (10(-5) m). 3. Preincubation of the tissue with 2-CAD (10(-4), 10(-5) or 10(-6) m) for 5 min raised the threshold concentration of CaCl2 to evoke contractile response and also significantly increased the mean EC50 values of CaCl2. Nifedipine was found to be more potent than 2-CAD on Ca2+ channels. 4. The results of the present study suggest that the endogenous adenosine plays a significant role in producing vascular relaxation through the participation of A2 receptor subtype. This effect may be due to its inhibitory effect on release of Ca2+ from the intracellular stores. Further to this effect, 2-CAD had a major inhibitory effect on voltage-operated Ca2+ channels compared with receptor-operated Ca2+ channels. 5. It can be concluded that adenosine through its A2 receptor produces vasorelaxant effect by interfering with the release of Ca2+ from the intracellular stores coupled with influx of Ca2+ from the extracellular sources.

Use of telemedicine in evading cholera outbreak in Mahakumbh Mela, Prayag, UP, India: an encouraging experience

Telemedicine (TM) services a process in which expert medical advice from afar is provided using electronic signals to transfer the medical data from one site to another. As a pilot project to assess the efficacy of TM in developing countries like India, a telemedicine center was set up at the main hospital of Mahakumbh mela--a grand religious fair, at Prayag, a city in north India. The daily reporting of the in-patient and outpatient cases at the fair revealed a surge of diarrhea cases among the pilgrims at the fair. This information was communicated to the referral center at Sanjay Gandhi Post Graduate Institute of Medical Sciences (SGPGIMS), which, with the help of its microbiology department, conducted microbiological examinations of stool samples and rectal swabs of patients along with various water samples. Vibrio cholerae was isolated in 22.6% (7/31) of the samples. This information was immediately relayed to the Main Hospital at the fair online, and then to the health authorities, who took strict and prompt measures to improve hygiene. Subsequently, the number of diarrhea cases decreased considerably in a matter of a few days, and thus an epidemic disaster was averted, which could have created havoc in such a large gathering.

Expression of the ecto-ATPase NTPDase2 in the germinal zones of the developing and adult rat brain

In the adult nervous system, multipotential stem cells of the subventricular zone of the lateral ventricles generate neuron precursors (type-A cells) that migrate via the rostral migratory stream to the olfactory bulb where they differentiate into neurons. The migrating neuroblasts are surrounded by a sheath of astrocytes (type-B cells). Using immunostaining, in situ hybridization and enzyme histochemistry, we demonstrate that the ecto-ATPase nucleoside triphosphate diphosphohydrolase 2 (NTPDase2) is expressed in the subventricular zone and the rostral migratory stream of the adult rat brain. This enzyme hydrolyses extracellular nucleoside triphosphates to the respective nucleoside diphosphates and is thought to directly modulate ATP receptor-mediated cell communication. Double labelling for the astrocyte intermediate filament protein GFAP and the glial glutamate transporter GLAST identifies the NTPDase2-positive cells as type-B cells. During development the enzyme protein is first detected at E18, long before expression of the astrocyte marker GFAP. It gradually becomes expressed along the ventricular and subventricular zone of the brain, followed by complete retraction to the adult expression pattern at P21. NTPDase2 is transiently expressed in the outer molecular layer of the dentate gyrus and within the cerebellar white matter and is associated with select microvessels, tanycytes of the third ventricle, and subpial astrocytes of the adult brain. Our results suggest that NTPDase2 can serve as a novel marker for specifying subsets of cells during in vivo and in vitro studies of neural development and raise the possibility that ATP-mediated signalling pathways play a role in neural development and differentiation.

Myxoma of maxilla

A case of Myxoma involving left Maxilla, presenting as swelling of left side of face and Oral cavity with bilateral nasal obstruction is reported.

Primary hyperparathyroidism in India

Background

Primary hyperparathyroidism (PHPT) in Indians has some unique clinical features, such as early age of onset, extreme osteopenia, crippling bone involvement, large parathyroid tumours, higher proportion of malignancy and severe, prolonged postparathyroidectomy hungry bone syndrome. The current study aimed to study (1) whether these features of PHPT in Indians are due to a variant form of PHPT and (2) pathogenetic factors of such variant disease.

Methods

Clinical, investigative and pathological features of 29 consecutive patients with PHPT (24 females, five males) who underwent parathyroidectomy at 13–60 (mean 38) years of age were reviewed. Spearman's correlation coefficient was calculated between serum calcidiol levels and biochemical variables, bone mineral density (BMD) before surgery and parathyroid tumour weight.

Results

Median duration of symptoms was 2·5 (range 1–26) years. Mean total serum calcium, iPTH and ALP levels were 12·4 mg dl−1 (normal 8·5–10·8 mg dl−1), 955 pg ml−1 (normal 9–55 pg ml−1) and 850 units l−1 (normal 35–125 units l−1) respectively, while mean(s.d.) serum calcidiol and calcitriol concentrations were 14(6) ng ml−1 and 52(29) pg ml−1 (versus 9(9) and 30(14) pg ml−1 in matched controls). All patients had symptomatic osteitis fibrosa cystica and eight were bedridden. Single or multiple spontaneous fractures occurred in 14 patients, brown tumours in 20, and long bones were barely visible on plain films in four. BMD z-scores at distal radius and lumbar spine (mean) were −4·2 and −3·8. Palpable parathyroid tumours occurred in 14 patients and nine had renal damage, mainly nephrocalcinosis. Parathyroidectomy invariably resulted in long-standing severe hypocalcaemia, necessitating intravenous calcium infusion for 6 days on average, and long-term oral calcium and vitamin D supplementation. The mean parathyroid gland weight was 8·6 (range 2–36·6) g and signs of carcinoma were found in four. There was a negative correlation (P < 0·05) between serum calcidiol and serum iPTH, and serum ALP and parathyroid gland weight.

Conclusion

PHPT in Indians manifests as severe, symptomatic musculoskeletal and renal disease. In spite of the severe hyperparathyroidism, the serum calcium levels are only moderately raised. These patients have signs of rapid parathyroid tumour growth resulting in large adenomas and a high proportion of parathyroid carcinomas. The signs of rapid cell proliferation, excessive calcium insensitivity of PTH release and peripheral PTH resistance may clarify roles of widely prevalent vitamin D deficiency in pathogenesis of this variant of PHPT.

Unique clinical characteristics of primary hyperparathyroidism in India

Background

The features of primary hyperparathyroidism (PHPT) in developing countries have rarely been examined. This study explored the clinical characteristics of PHPT in India with the hypothesis that this may improve understanding of the pathogenesis of the disease worldwide.

Methods

Consecutive patients with PHPT (24 women, five men) were examined prospectively before and after parathyroidectomy.

Results

All patients had osteitis fibrosa cystica with a median symptom duration of 2·5 (range 1–26) years. Single or multiple fragility fractures were present in 14 patients (eight were bedridden); 20 had brown tumours. Mean preoperative serum calcium was 3·1 mmol/l, while mean serum intact parathyroid hormone (iPTH) and total alkaline phosphatase (ALP) levels were 17-fold and 12-fold higher than normal respectively. Nine patients had overt renal damage, mainly nephrocalcinosis. Parathyroidectomy invariably resulted in severe hypocalcaemia, necessitating long-term vitamin D treatment. The mean parathyroid gland weight was 8·6 (range 2·0–36·6) g and features of carcinoma were found in four patients. Serum calcidiol level correlated inversely (P < 0·05) with serum iPTH and ALP, and parathyroid gland weight.

Conclusion

PHPT in Indians is a severe, symptomatic disorder with skeletal, muscular and renal manifestations at a young age. The presence of this severe variant of PHPT in vitamin D-sufficient Indians, and the lack of skeletal disease in other vitamin D-deficient populations, raises the possibility of additional pathogenetic factors.

Effects of mibefradil on uterine contractility

Mibefradil, a benzimidazolyl tetralol derivative, is a new Ca(2+) channel antagonist which is structurally distinct from other Ca(2+) channel antagonists such as nifedipine, verapamil and diltiazem. It is a very effective antihypertensive agent that is thought to achieve its action via a higher affinity block for low-voltage activated (T) than for high-voltage-activated (L) Ca(2+) channels. Nevertheless, it blocks L-type Ca(2+) channels in several tissues. In the present study, the effects of mibefradil on spontaneous rhythmic contractions and on contractions elicited by CaCl(2) (K(+)-depolarized preparations) and oxytocin (in low Ca(2+)/Ca(2+)-free solutions) were investigated on uterus strips from pregnant and non-pregnant rats. Mibefradil (10(-8)-3 x 10(-6) M) caused concentration-dependent inhibition of spontaneous contractions of uterus strips from pregnant and non-pregnant rats with the IC(50) values of 8.83 x 10(-7) M; 5.94 x 10(-7) M (amplitude) and 1.03 x 10(-6) M; 5.48 x 10(-7) M (frequency), respectively. Mibefradil (3 microM) caused a rightward shift in the concentration-response curves for CaCl(2) in K(+) (40 mM)-depolarized uterus strips taken from both pregnant and non-pregnant rats. Mibefradil (3 microM) was, however, more potent for antagonising CaCl(2) responses in uterus strips obtained from pregnant rats than in those from non-pregnant rats. Mibefradil (3 microM) had no effect on oxytocin-induced contraction in Ca(2+)-free physiological salt solution (PSS) on uterus strips from non-pregnant rats. However, it markedly inhibited oxytocin-induced contraction of pregnant rat uterus strips in Ca(2+)-free PSS. Thus, mibefradil probably antagonizes L-type Ca(2+) channels as well as interferes with the intracellular Ca(2+) release mechanism, which would be helpful in the development of a tocolytic agent.

Functional analysis of a chromosomal arsenic resistance operon in Pseudomonas fluorescens strain MSP3

We reported earlier about the detection of a chromosomally located arsenic operon (arsRBC) in a gram-negative bacterium Pseudomonas fluorescens strain MSP3, which showed resistance to elevated levels of sodium arsenate and sodium arsenite. The genes for arsenic resistance were cloned into the HindIII site of pBluescript vector producing three clones MSA1, MSA2 and MSI3 conferring resistance to sodium arsenate and arsenite salts. They were further sub-cloned to delineate the insert size and the sub-clones were designated as MSA11, MSA12 and MSI13. The sub-clone pMSA12 (2.6 kb) fragment was further packaged into EcoRI-PstI site of M13mp19 and sequenced. Nucleotide sequencing revealed the presence of three open reading frames homologous to the arsR, arsB and arsC genes of arsenic resistance. Three cistrons of the ars operon encoded polypeptides ArsR, ArsB and ArsC with molecular weights ranging approximately 12, 37and 24 kDa, respectively. These polypeptides were visualized on SDS-PAGE stained with Coomassie blue and measured in a densitometer. The arsenic resistance operon (arsRBC) of strain MSP3 plasmid pMSA12 consists of 3 genes namely, arsR--encoding a repressor regulatory protein, arsB--the determinant of the membrane efflux protein that confers resistance by pumping arsenic from the cells and arsC--a small cytoplasmic polypeptide required for arsenate resistance only, not for arsenite resistance. ArsB protein is believed to use the cell membrane potential to drive the efflux of intracellular arsenite ions. ArsC encodes for the enzyme arsenate reductase which reduces intracellular As(V) (arsenate) to more toxic As(III) (arsenite) and is subsequently extruded from the cell. The arsenate reductase activity was present in the soluble cytoplasmic fraction in E. coli clones. In the context of specified function of the arsenic operon encoded proteins, uptake and efflux mechanisms were studied in the wild strain and the arsenate/arsenite clones. The cell free filtrates of the arsenate clones (MSA11 and MSA12) obtained from P. fluorescens containing the arsC gene showed that arsenate reduction requires glutathione reductase, glutathione (GSH), glutaredoxin and ArsC protein. The protein was purified in an active form and a spectrophotometric assay was developed in which the oxidation of NADPH was coupled to reduction of arsenate. The molecular weights and the location of the polypeptides were obtained from Coomassie stained SDS-PAGE of extracellular and intracellular fractions of the cells.

An ab initio theoretical study of electronic structure and properties of 2'-deoxyguanosine in gas phase and aqueous media

Molecular geometries of two structural forms of 2'-deoxyguanosine (keto-N9R and keto-N7R, R = the sugar moiety) considering both the C2'-endo and C3'-endo conformations of the sugar ring and those of the complexes of these species with two water molecules each were optimized employing the ab initio RHF procedure. A mixed basis set consisting of the 6-311+G* basis set for the nitrogen atom of the amino group and the 4-31G basis set for all the other atoms was used. The RHF calculations were followed by correlation correction of the total energy at the MP2 level. Both the structural forms of 2'-deoxyguanosine were solvated using the polarized continuum model (PCM) of the self-consistent reaction field (SCRF) theory and the corresponding RHF optimized geometries at the RHF and MP2 levels. Geometry optimization was also performed in aqueous media using the Onsager model at the RHF level using the above-mentioned mixed basis set, and subsequently, using the reoptimized geometries, single-point MP2 calculations were performed. It is found that both the keto-N9R and keto-N7R forms of 2'-deoxyguanosine as well as their complexes with two water molecules each would occur, particularly at the water-air interface. Though the normal Watson-Crick-type base pairing would not be possible with the keto-N7R form of 2'-deoxyguanosine(G*), two other (G*-C and G*-T) base pairing schemes may occur with this form of the nucleoside, which may cause mutation. The present calculated geometry of the keto-N9R form of the anti-conformation of 2'-deoxyguanosine including the dihedral angle chi(CN) agree satisfactorily with the available crystallographic results. The present results also agree satisfactorily with those obtained by other authors earlier for the keto-N9R form of 2'-deoxyguanosine using B3LYP and MP2 methods employing the 6-31G* basis set. Using transition state calculations, it is shown that tautomerism of guanine and other similar molecules where the tautomers would coexist would be facilitated by the occurrence of the H(+) and OH(-) fragments of water molecules. Further, this coexistence of the two tautomers appears to make the C8 carbon atom located between the N7 and N9 nitrogen atoms susceptible to attack by the OH(-) group. Thus, an explanation is obtained for the efficient formation of the reaction product 8-hydroxy-2'-deoxyguanosine, which serves as a biomarker for oxidative damage to DNA in biological systems.

Surgical treatment of sternal metastases from thyroid carcinoma: report of two cases

Radioiodine therapy is currently the treatment of choice for metastasizing differentiated thyroid cancer (DTC); however, skeletal metastases are resistant to this form of therapy. The surgical removal of distant metastases from DTC offers the best chance for prolonged survival and improved quality of life. Furthermore, the surgical removal of a resectable skeletal metastasis can be a valuable complement to radioiodine therapy. This report describes two cases of sternal metastases from thyroid carcinoma that were managed successfully by surgery involving partial excision of the sternum followed by reconstruction of the chest wall with Marlex mesh. Both patients recovered uneventfully. Sternal resection with Marlex mesh reconstruction of the chest wall defect proved a simple and effective method for managing sternal metastasis. Thus, the surgical resection of distant bony metastases in patients with DTC is recommended as it can be curative, provide symptomatic palliation, or allow for more effective radioiodine treatment.

Clathrin- and AP-2-binding sites in HIP1 uncover a general assembly role for endocytic accessory proteins

Clathrin-mediated endocytosis is a major pathway for the internalization of macromolecules into the cytoplasm of eukaryotic cells. The principle coat components, clathrin and the AP-2 adaptor complex, assemble a polyhedral lattice at plasma membrane bud sites with the aid of several endocytic accessory proteins. Here, we show that huntingtin-interacting protein 1 (HIP1), a binding partner of huntingtin, copurifies with brain clathrin-coated vesicles and associates directly with both AP-2 and clathrin. The discrete interaction sequences within HIP1 that facilitate binding are analogous to motifs present in other accessory proteins, including AP180, amphiphysin, and epsin. Bound to a phosphoinositide-containing membrane surface via an epsin N-terminal homology (ENTH) domain, HIP1 associates with AP-2 to provide coincident clathrin-binding sites that together efficiently recruit clathrin to the bilayer. Our data implicate HIP1 in endocytosis, and the similar modular architecture and function of HIP1, epsin, and AP180 suggest a common role in lipid-regulated clathrin lattice biogenesis.

Reversal of catecholamine induced cardiomyopathy in a patient with bilateral malignant pheochromocytoma

A patient of catecholamine induced cardiomyopathy (CMP) due to bilateral malignant adrenal pheochromocytoma (PCC), successfully reversed on treatment is described here. To the best of our knowledge, this is first report of catecholamine induced CMP due to bilateral malignant adrenal PCC, which could be reversed after surgery.

Multicentric clinical trials for safety and efficacy evaluation of alpha;beta arteether in complicated P. falciparum malaria

OBJECTIVE

To evaluate efficacy of alpha;beta arteether in patients of P. falciparum malaria presenting with complications was undertaken in a multicentric clinical trial.

METHOD

Each patient who consented to undergo clinical trial with parenteral Arteether was treated with a fixed dose schedule of Arteether given intramuscularly in a dose of 150 mg once a day on three consecutive days. Every patient was followed upto 28 days with clinical, haematological and parasitological monitoring every day upto one week and thereafter at 14, 21 and 28 days. The response was assessed in terms of fever clearance time, parasite clearance time, cure rate and parasite reappearance rate.

RESULTS

A total of 211 patients of P. falciparum malaria were included in the study from four centres (Bhilai, Guwahati, Jamshedpur and Rourkela). Results of this study showed that fever clearance time ranged between 24-168 hours, parasite clearance time ranged between 24-120 hours and overall mortality ranged between 4-8.5%. Out of 211, only 14 patients expired during the study, of these, 10 patients expired within first two days i.e. before completing the three day schedule of arteether therapy. Tolerability to arteether injection was good in all these patients and no untoward effects were experienced or reported during the study. Overall cure rate observed in these studies was 93%.

CONCLUSION

This study shows a rapid parasite and fever clearance in patients of complicated P. falciparum malaria.