Biomedical subjects

B S Shah

Publications and source records attributed to B S Shah.

14 recordsLinked to original sources

PubMed2001

Beta3, a novel auxiliary subunit for the voltage gated sodium channel is upregulated in sensory neurones following streptozocin induced diabetic neuropathy in rat.

In the present study we have used in situ hybridization to examine the changes in mRNA expression of the voltage gated sodium channel subunits beta1 and beta3, which occur in response to streptozocin induced diabetic neuropathy. Under control conditions beta1 mRNA was detected throughout the spinal cord and in large dorsal root ganglion (DRG) Abeta fibres whilst beta3 mRNA was expressed exclusively in the layers I/II and X of the spinal cord and in small DRG c-fibres. Following streptozocin treatment, the expression of beta1 mRNA remained unchanged in both the spinal cord and DRG whilst beta3 message was significantly increased in both the spinal cord and in medium diameter Adelta type DRG neurones. In conclusion, the present study illustrates that the development of the neuropathic pain state is associated with distinct changes in the pattern of beta3 subunit expression and that these changes appear to be specific to the neuropathic pain state induced.

Animals↗

PubMed2001

Developmental expression of the novel voltage-gated sodium channel auxiliary subunit beta3, in rat CNS.

1. We have compared the mRNA distribution of sodium channel alpha subunits known to be expressed during development with the known auxiliary subunits Nabeta1.1 and Nabeta2.1 and the novel, recently cloned subunit, beta3. 2. In situ hybridisation studies demonstrated high levels of Nav1.2, Nav1.3, Nav1.6 and beta3 mRNA at embryonic stages whilst Nabeta1.1 and Nabeta2.1 mRNA was absent throughout this period. 3. Nabeta1.1 and Nabeta2.1 expression occurred after postnatal day 3 (P3), increasing steadily in most brain regions until adulthood. beta3 expression differentially decreased after P3 in certain areas but remained high in the hippocampus and striatum. 4. Emulsion-dipped slides showed co-localisation of beta3 with Nav1.3 mRNA in areas of the CNS suggesting that these subunits may be capable of functional interaction. 5. Co-expression in Xenopus oocytes revealed that beta3 could modify the properties of Nav1.3; beta3 changed the equilibrium of Nav1.3 between the fast and slow gating modes and caused a negative shift in the voltage dependence of activation and inactivation. 6. In conclusion, beta3 is shown to be the predominant beta subunit expressed during development and is capable of modulating the kinetic properties of the embryonic Nav1.3 subunit. These findings provide new information regarding the nature and properties of voltage-gated sodium channels during development.

Aging↗

PubMed2001

Tissue distribution and functional expression of the human voltage-gated sodium channel beta3 subunit.

This study investigated the distribution of beta3 in human tissues and the functional effects of the human beta3 subunit on the gating properties of brain and skeletal muscle alpha subunits. Using RT-PCR of human cDNA panels, beta3 message was detected in brain, heart, kidney, lung, pancreas and skeletal muscle. Both alphaIIA and SkM1 expressed in Xenopus oocytes inactivated with a time course described by two exponential components representing fast and slow gating modes, while co-expression of human beta3 with alphaIIA or SkM1 significantly increased the proportion of channels operating by the fast gating mode. In the presence of beta3 a greater proportion of alphaIIA or SkM1 current was described by the fast time constant for both inactivation and recovery from inactivation. beta3 caused a hyperpolarizing shift in the voltage dependence of inactivation of alphaIIIA and reduced the slope factor. The voltage dependence of inactivation of SkM1 was described by a double Boltzmann equation. However, SkM1 co-expressed with beta3 was described by a single Boltzmann equation similar to one of the Boltzmann components for SkM1 expressed alone, with a small positive shift in V1/2 value and reduced slope factor. This is the first study demonstrating that beta3 is expressed in adult mammalian skeletal muscle and can functionally couple to the skeletal muscle alpha subunit, SkM1.

Amino Acid Sequence↗

PubMed2001

Pattern of cancer in Dayanand Medical College & Hospital, Ludhiana (a ten year retrospective study).

A ten year retrospective study was undertaken to ascertain the pattern and incidence of cancer in Ludhiana which is an industrial town with catchment area of Ludhiana consisting of Ludhiana distt., Sangrur, Jalandhar, Hoshiarpur, Faridkot, Ferozepur, Ropar, Kapurthala, some parts of Himachel Pradesh and Haryana. A total number of 56,565 biopsies were received for histopathological examinaiton in 10 years and 4,730 cases of cancer were diagnosed. The incidence of total malignant tumors was 8.36%. Females out numbered males in the incidence of cancer, with male to female ratio being 1:1.09. Most of the cancers were seen in the age group of 41-50 years. In females the two most common cancer sites were breast (21.07%) and cervix (19.4%) while in males hypopharynx--larynx (13.94%) and prostate (9.65%) were the most common sites of cancer.

Adult↗

PubMed2000

beta3, a novel auxiliary subunit for the voltage-gated sodium channel, is expressed preferentially in sensory neurons and is upregulated in the chronic constriction injury model of neuropathic pain.

Adult dorsal root ganglia (DRG) have been shown to express a wide range of voltage-gated sodium channel alpha-subunits. However, of the auxiliary subunits, beta1 is expressed preferentially in only large- and medium-diameter neurons of the DRG while beta2 is absent in all DRG cells. In view of this, we have compared the distribution of beta1 in rat DRG and spinal cord with a novel, recently cloned beta1-like subunit, beta3. In situ hybridization studies demonstrated high levels of beta3 mRNA in small-diameter c-fibres, while beta1 mRNA was virtually absent in these cell types but was expressed in 100% of large-diameter neurons. In the spinal cord, beta3 transcript was present specifically in layers I/II (substantia gelatinosa) and layer X, while beta1 mRNA was expressed in all laminae throughout the grey matter. Since the pattern of beta3 expression in DRG appears to correlate with the TTX-resistant voltage-gated sodium channel subunit PN3, we co-expressed the two subunits in Xenopus oocytes. In this system, beta3 caused a 5-mV hyperpolarizing shift in the threshold of activation of PN3, and a threefold increase in the peak current amplitude when compared with PN3 expressed alone. On the basis of these results, we examined the expression of beta-subunits in the chronic constriction injury model of neuropathic pain. Results revealed a significant increase in beta3 mRNA expression in small-diameter sensory neurons of the ipsilateral DRG. These results show that beta3 is the dominant auxiliary sodium channel subunit in small-diameter neurons of the rat DRG and that it is significantly upregulated in a model of neuropathic pain.

Animals↗

PubMed1999

Bombesin receptors inhibit G protein-coupled inwardly rectifying K+ channels expressed in Xenopus oocytes through a protein kinase C-dependent pathway.

Although activation of G protein-coupled inward rectifying K+ (GIRK) channels by Gi/Go-coupled receptors has been shown to be important in postsynaptic inhibition in the central nervous system, there is also evidence to suggest that inhibition of GIRK channels by Gq-coupled receptors is involved in postsynaptic excitation. In the present study we addressed whether the Gq-coupled receptors of the bombesin family can couple to GIRK channels and examined the mechanism by which this process occurs. Different combinations of GIRK channel subunits (Kir3.1, Kir3.2, and Kir3.4) and bombesin receptors (BB1 and BB2) were expressed in Xenopus oocytes. In all combinations tested GIRK currents were reversibly inhibited upon application of the bombesin-related peptides, neuromedin B or gastrin-releasing peptide in a concentration-dependent manner. Incubation of oocytes in the phospholipase C inhibitor U73122 or the protein kinase C (PKC) inhibitors chelerythrine and staurosporine significantly reduced the inhibition of GIRK currents by neuromedin B, whereas the Ca2+ chelator, BAPTA-AM had no effect. The involvement of PKC was further demonstrated by direct inhibition of GIRK currents by the phorbol esters, phorbol-12,13-dibutyrate and phorbol-12-myristate-13-acetate. In contrast, the inactive phorbol ester 4alpha-phorbol and protein kinase A activators, forskolin and 8-bromo cAMP did not inhibit GIRK currents. At the single-channel level, direct activation of PKC using phorbol ester phorbol-12, 13-dibutyrate caused a dramatic reduction in open probability of GIRK channels due to an increase in duration of the interburst interval.

Animals↗

PubMed1996

Renal amyloidosis--a clinicopathologic study.

A total of 19,075 necropsies and 1169 renal biopsies were scrutinised over a period of 20 years (1973-1992) retrospectively with an aim to study the incidence and pattern of renal amyloidosis in Nair Hospital. A total of 75 cases with amyloidosis were detected, 33 from the necropsy series (0.162%) and 42 from biopsies (3.59%). Secondary amyloidosis was seen in 82.66% and primary amyloidosis in 10.66%. Tuberculosis of various organs was the main cause of secondary amyloidosis (79.03%). Nephrotic syndrome was the common mode of presentation (52%). Besides kidney, which were involved in all cases, the liver, spleen and adrenals were other commonly involved organs at necropsy. Renal failure was the leading cause of death (51.51%). Thioflavine-T proved to be more sensitive technique than other conventional staining methods. The potassium permanganate test is a useful test to distinguish secondary amyloid fibrils from other amyloid fibrils. Abdominal fat aspiration may prove to be specific, sensitive and a routine procedure enabling the early diagnosis of amyloidosis leading to increased incidence of amyloidosis during life than at necropsy.

Adult↗

PubMed1993

Anti-convulsant drugs, smoking, and body weights in psychiatric in-patients.

Some anti-convulsant drugs have a calming effect that may potentially be used to reduce cigarette smoking. A cross-sectional study, including all 100 psychiatric in-service patients receiving various anti-convulsant drugs and their age- and sex-matched controls, was done. The intensity of their daily cigarette smoking and their body weights were recorded. Of the patients, 25% were non-smokers. Of the 22 patients on phenytoin, eight were non-smokers as opposed to three in the control group. Two thirds of the phenytoin group patients were either non-smokers, or were nominal smokers. As opposed to this, of the control patients and those on other anti-convulsants, two thirds were either moderate or heavy smokers. The phenytoin group of patients weighed less than the controls (149 v 163 lbs). Valproic acid therapy was associated with a significantly higher body weight and with more smoking. Clonazepam's effect was similar to valproic acid, but carbamazepine did not show any relationship either with smoking or with body weights. Therapy with phenytoin is associated with a lower prevalence and a lower intensity of cigarette smoking, together with lower body weights in psychiatric in-patient population.

Adult↗

PubMed1992