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Biomedical subjects

S K Joshi

Publications and source records attributed to S K Joshi.

At least 19 recordsLinked to original sources

Comparison of antinociceptive actions of standard analgesics in attenuating capsaicin and nerve-injury-induced mechanical hypersensitivity.

Intradermal capsaicin injection produces immediate spontaneous pain behaviors, and a secondary mechanical hypersensitivity (SMH) that is employed in the clinic as a model potentially predictive of human neuropathic pain. Presently, we have characterized capsaicin-induced SMH in rats, and compared pharmacological actions of standard analgesics in this and two nerve injury models, the L5/L6 spinal nerve ligation (SNL) and sciatic nerve chronic constriction injury (CCI) models. Intraplantar capsaicin produced dose-related SMH (enhanced paw withdrawal response to von Frey monofilament stimulation at an area away from injection site) that lasted for over 4 h. While pretreatment with a potent selective transient receptor potential vanilloid receptor-1 (TRPV1) antagonist A-425619 (1-isoquinolin-5-yl-3-(4-trifluoromethyl-benzyl)-urea) prevented development of acute nocifensive (flinching) behavior immediately following capsaicin injection (ED(50)=4.9 mg/kg), the compound failed to attenuate the SMH when administered 2 h following capsaicin (10 microg/10 microl). Additional standard analgesics were also tested 3 h following intraplantar capsaicin in the SMH model. Comparison of their potencies in attenuating mechanical hypersensitivity in capsaicin, SNL and CCI models revealed similar ED(50)s for morphine (2.3 mg/kg, 1.6 mg/kg and 3.2 mg/kg, respectively), gabapentin (33.1 mg/kg, 33.9 mg/kg and 26.3 mg/kg, respectively) and lamotrigine (9.1 mg/kg, 8.9 mg/kg and 15.5 mg/kg, respectively). Duloxetine produced 50-65% effect at the highest tested dose (50 mg/kg), whereas the highest tested doses of morphine (10 mg/kg), gabapentin (85.5 mg/kg) and lamotrigine (30 mg/kg) all produced >70% efficacy in capsaicin SMH, SNL and CCI models. In contrast, celecoxib and ibuprofen showed weak effects in all three models. All standard analgesics generally had weak efficacy in attenuating capsaicin-induced immediate acute flinching behavior when administered before capsaicin. These results provide further support to the suggestions that distinct pharmacological mechanisms underlie capsaicin-induced acute nocifensive and SMH behaviors, and certain neuronal mechanisms underlying neuropathic pain states are also contributory to capsaicin-induced SMH.

Analgesics↗

Involvement of the TTX-resistant sodium channel Nav 1.8 in inflammatory and neuropathic, but not post-operative, pain states.

Antisense (AS) oligodeoxynucleotides (ODNs) targeting the Nav 1.8 sodium channel have been reported to decrease inflammatory hyperalgesia and L5/L6 spinal nerve ligation-induced mechanical allodynia in rats. The present studies were conducted to further characterize Nav 1.8 AS antinociceptive profile in rats to better understand the role of Nav 1.8 in different pain states. Consistent with earlier reports, chronic intrathecal Nav 1.8 AS, but not mismatch (MM), ODN decreased TTX-resistant sodium current density (by 60.5+/-10.2% relative to MM; p<0.05) in neurons from L4 to L5 dorsal root ganglia and significantly attenuated mechanical allodynia following intraplantar complete Freund's adjuvant. In addition, 10 days following chronic constriction injury of the sciatic nerve, Nav 1.8 AS, but not MM, ODN also attenuated mechanical allodynia (54.3+/-8.2% effect, p<0.05 vs. MM) 2 days after initiation of ODN treatment. The anti-allodynic effects remained for the duration of the AS treatment, and CCI rats returned to an allodynic state 4 days after discontinuing AS. In contrast, Nav 1.8 AS ODN failed to reduce mechanical allodynia in the vincristine chemotherapy-induced neuropathic pain model or a skin-incision model of post-operative pain. Finally, Nav 1.8 AS, but not MM, ODN treatment produced a small but significant attenuation of acute noxious mechanical sensitivity in naïve animals (17.6+/-6.2% effect, p<0.05 vs. MM). These data demonstrate a greater involvement of Nav 1.8 in frank nerve injury and inflammatory pain as compared to acute, post-operative or chemotherapy-induced neuropathic pain states.

Animals↗

Complete 1H and 13C NMR assignments of six saponins from Sapindus trifoliatus.

Complete 1H and 13C spectral assignments are reported for six saponins from the pericarp of Sapindus trifoliatus (Hindi name: Reetha) collected from Madhya Pradesh and Maharashtra, India, using only 1D and 2D NMR methods. The structures of the compounds were elucidated as hederagenin 3-O-(3-O-acetyl-beta-D-xylopyranosyl)-(1-3)-alpha-L-rhamnopyranosyl-(1-2)-alpha-L-ara-binopyranoside, hederagenin 3-O-(4-O-acetyl-beta-D-xylop-yranosyl)-(1-3)-alpha-L-rhamnopyranosyl-(1-2)-alpha-L-arabinop-yranoside, hederagenin 3-O-(3,4-O-diacetyl-beta-D-xylopy-ranosyl)-(1-3)-alpha-L-rhamnopyranosyl-(1-2)-alpha-L-arabinopy-ranoside, hederagenin 3-O-(3,4-O-diacetyl-alpha-L-arabinop-yranosyl)-(1-3)-alpha-L-rhamnopyranosyl-(1-2)-alpha-L-arabinop-yranoside, hederagenin 3-O-(beta-D-xylopyranosyl)-(1-3)-alpha-L-rhamnopyranosyl-(1-2)-alpha-L-arabinopyranoside and he-deragenin 3-O-(alpha-L-arabinopyranosyl)-(1-3)-alpha-L-rhamno-pyranosyl-(1-2)-alpha-L-arabinopyranoside. It is concluded that saponins of this complexity approach the limit of structural complexity, which can be solved by NMR alone, precisely and quickly.

Carbon Isotopes↗

Combining ability in the F1 and F2 generations of diallel cross in hexaploid wheat (Triticum aestivum L. em. Thell).

The F(1) and F(2) progenies of a ten-parent diallel cross (excluding reciprocals) of hexaploid wheat (Triticum aestivum L. em. Thell) were analyzed for combining ability for quantitative and quality traits. The results indicated significant differences among the parents for general combining ability (gca) and crosses for specific combining ability (sca) for all the characters studied. The gca and sca components of variance were significant for all the traits. However, the gca component of variance was predominant indicating the predominance of additive gene effects for the traits studied. Among the parents Durgapura 65, HD 2285, Lok-1, Raj 1972 and HD 2329 were the best general combiners for grain yield and average to high combiners for tillers per plant, grain yield per spike, grains per spike and 1000-grain weight. The best specific crosses for grain yield were Sonalika x WH 157, HD 2428 x Durgapura 65, Durgapura 65 x Sonalika, HD 2428 x Lok-1 and CPAN 3004 x Raj 1972. The parent Raj 1972, Lok-1 and HD 2285 were the best general combiners for grain yield and protein content, however, Raj 3077 was the best general combiner for protein content. The most suitable specific crosses for protein content were HD 2329 x HD 2285, HD 2428 x Raj 1972 and CPAN 3004 x WH 157. Most of the specific crosses for grain yield as well as protein content involved high x average, average x average and average x poor general combiners. To ensure further increase in grain yield along with high protein, combinations of desirable yield components is advocated. Inclusion of F(1) hybrids showing high sca and having parents with good gca, into multiple crosses and/or bi-parental mating, or diallel selective mating could prove a worthwhile approach for further improvement of grain yield in bread wheat.

Analysis of Variance↗

Arylacetamide kappa-opioid receptor agonists produce a tonic- and use-dependent block of tetrodotoxin-sensitive and -resistant sodium currents in colon sensory neurons.

We have previously reported that U50,488 [(trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzeneacetamide] enantiomers contribute to visceral antinociception by a nonopioid receptor-mediated blockade of sodium currents in colon sensory neurons. The present experiments were undertaken to examine the effect of arylacetamide kappa-opioid receptor agonists (kappa-ORAs) U50,488 and EMD 61,753 [(N-methyl-N-[1S)-1-phenyl)-2-(13S))-3-hydroxypyrrolidine-1-yl)-ethyl]-2,2-diphenylacetamide HCl] on tetrodotoxin-sensitive (TTX-S) and -resistant (TTX-R) sodium currents, and the mechanism of their sodium channel-blocking actions. Whole cell patch-clamp experiments were performed on colon sensory neurons from the S1 dorsal root ganglion identified by content of retrograde tracer 1.1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine metanesulfonate. The concentration-response curves of U50,488 and EMD 61,753, for tonic inhibition of total, TTX-S, and TTX-R sodium currents were similar (EC50 values for U50,488 and EMD 61,753 were 8.4 +/- 1.69 and 1.2 +/- 1.78 microM, respectively). In contrast, the peptide kappa-ORA dynorphin was without effect in these experiments. U50,488 (10 microM) shifted the voltage dependence of steady-state inactivation curves for total, TTX-S, and TTX-R currents to more negative potentials. Inhibition was present at holding potentials of -100 to -20 mV. After the tonic block elicited by 10 microM U50,488, repetitive stimulation with 5-ms depolarizing pulses at a frequency of 3 Hz further enhanced the inhibition of total, TTX-R, and TTX-S currents by 43.8 +/- 4.9, 46.2 +/- 4.9, and 40 +/- 3.2%, respectively. These results demonstrate that arylacetamide kappa-ORAs nonselectively inhibit voltage-evoked sodium currents in a manner similar to local anesthetics, by enhancing closed-state inactivation and induction of use-dependent block.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

Nonopioid actions of U50,488 enantiomers contribute to their peripheral cutaneous antinociceptive effects.

The ability of arylacetamide kappa-opioid receptor agonists (kappa-ORAs) to block sodium channels by a nonopioid mechanism has been previously documented. The present experiments were undertaken to test whether two enantiomers of the arylacetamide kappa-ORA (trans)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzeneacetamide (U50,488), (+)-(1R,2R)-U50,488 and (-)-(1S,2S)-U50,488, are antinociceptive in the formalin model by a peripheral, nonopioid receptor-mediated mechanism. Although both enantiomers have been previously shown to block sodium channels with comparable potencies, only (-)-(1S,2S)-U50,488 has activity at the kappa-opioid receptor (KOR). In the formalin test, intrapaw administration of U50,488 enantiomers as well as lidocaine exhibited significant dose-related attenuation of formalin-induced flinching behavior. The rank order of potency of the drugs tested was (-)-(1S,2S)-U50,488 > (+)-(1R,2R)-U50,488 > lidocaine. The antinociception produced by lower doses of (-)-(1S,2S)-U50,488 was blocked by intrapaw nor-binaltorphimine as well as by antisense knockdown of the KOR. Such pretreatments, however, did not block the antinociception produced by (+)-(1R,2R) U50,488, lidocaine, or higher doses of (-)-(1S,2S)-U50,488. These data suggest that the sodium channel blocking effects of U50,488 and similar kappa-ORAs can contribute to their peripheral antinociceptive actions.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

Sodium channel blocking actions of the kappa-opioid receptor agonist U50,488 contribute to its visceral antinociceptive effects.

The goal of the present study was to determine whether the kappa-opioid receptor agonist (ORA) U50,488 attenuates behavioral and primary afferent nerve responses to noxious colorectal distension (CRD) by sodium channel blockade. We tested the analgesic kappa-ORA (+/-)-trans U50,488, its enantiomers (-)-trans (1S,2S)-U50,488 and non kappa-ORA (+)-trans (1R,2R)-U50,488, and/or its diastereomer (-)-cis (1S,2R)-U50,488 for their ability to attenuate visceromotor and pelvic nerve afferent fiber responses to noxious CRD in vivo and voltage-activated sodium current in colon sensory neurons in vitro. In unanesthetized rats, subcutaneous administration of U50,488, (1S,2S)-U50,488, and (1R,2R)-U50,488 attenuated the behavioral visceromotor response to noxious CRD; the rank order of potency was: (1S,2S)-U50,488 > U50,488 angle quotation mark, right (1R,2R)-U50,488. U50,488 and its stereoisomers also inhibited responses of decentralized pelvic nerve afferent fibers to noxious CRD in a dose-dependent manner. Cumulative doses of 16 mg/kg of (1S,2S)-U50,488, (1S,2R)-U50,488, and (1R,2R)-U50,488 reduced responses to a mean 29, 30, and 47% of control, respectively. The mean inhibitory doses of these drugs were not different (range: 6.6-10.8 mg/kg). Sodium channel blockers mexiletine and carbamazepine mimicked the effect of U50,488. In contrast, the kappa-ORAs dynorphin (1-13) and ICI 204,488 were ineffective in attenuating pelvic nerve activity. Perfusion of (1S,2S)-U50,488, (1S,2R)-U50,488, or (1R,2R)-U50,488 on colon sensory neurons in vitro decreased voltage-activated sodium currents. This inhibition by U50,488 and its stereoisomers was not opioid receptor-mediated because it could not be reversed by the opioid receptor antagonist naloxone and was also not a G protein-mediated effect. The results reported here suggest that the visceral antinociceptive effects of U50,488 and its stereoisomers are contributed to by their peripheral sodium channel blocking actions.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

Flexibility in MHC and TCR recognition: degenerate specificity at the T cell level in the recognition of promiscuous Th epitopes exhibiting no primary sequence homology.

Recognition of peptide Ags by T cells through the TCR can be highly specific. In this report we show the degeneracy of Ag recognition at both MHC and TCR levels. We present evidence that unrelated promiscuous Th cell epitopes from various protein sources exhibit sufficient structural homology, despite minimal structural identity, to elicit cross-reactive proliferative responses at the bulk T cell level. This epitopic mimicry was also observed when peptide (CS.T3(378-395) and TT(830-844))-specific CD4+ T cell lines and T cell hybridoma clones were used in proliferation and Ag presentation assays. A scrambled CS.T3(378-395) peptide did not show any proliferation, indicating that the specificity of the cross-reactive responses may be linked with the primary structure of the peptides. Blocking of CS.T3(378-395)-specific CD4+ T cell proliferation by anti-MHC class II mAb showed that recognition of promiscuous T cell epitopes is largely in association with MHC class II molecules. These findings suggest that promiscuous Th epitopes may be useful in designing peptide-based vaccine constructs. At the same time these results show that at the T cell level there may be a great deal of immunological cross-reactivity between heterologous pathogens, and because of this the host's response to a pathogen may be modified by its previous experience with other unrelated pathogens.

Amino Acid Sequence↗

Conditional vascular cell adhesion molecule 1 deletion in mice: impaired lymphocyte migration to bone marrow.

We generated vascular cell adhesion molecule (VCAM)-1 "knock-in" mice and Cre recombinase transgenic mice to delete the VCAM-1 gene (vcam-1) in whole mice, thereby overcoming the embryonic lethality seen with conventional vcam-1-deficient mice. vcam-1 knock-in mice expressed normal levels of VCAM-1 but showed loss of VCAM-1 on endothelial and hematopoietic cells when interbred with a "TIE2Cre" transgene. Analysis of peripheral blood from conditional vcam-1-deficient mice revealed mild leukocytosis, including elevated immature B cell numbers. Conversely, the bone marrow (BM) had reduced immature B cell numbers, but normal numbers of pro-B cells. vcam-1-deficient mice also had reduced mature IgD+ B and T cells in BM and a greatly reduced capacity to support short-term migration of transferred B cells, CD4+ T cells, CD8+ T cells, and preactivated CD4+ T cells to the BM. Thus, we report an until now unappreciated dominant role for VCAM-1 in lymphocyte homing to BM.

Animals↗

X-ray absorption near edge studies of some binuclear copper(II) complexes.

X-ray K-absorption near edge studies have been carried out on the binuclear copper (II) dithiocarbamate (dtc) complexes having the following general structure: [structure in text] where R = me (methyl); et (ethyl); npr (normal propyl); chx (cyclohexane) It has been found that the chemical shift values are higher in the chlorine adducts as compared to the values of chemical shift reported by us in an earlier work for the parent complexes, showing that the chlorine adducts are more ionic. The observed splitting of the principal absorption maximum (1s-4p) in the chlorine adducts has been explained in terms of the splitting of the metal 4p orbital degeneracy.

Cations, Divalent↗

kappa -opioid receptor agonists modulate visceral nociception at a novel, peripheral site of action.

kappa-opioid receptor agonists (kappa-ORAs) have been shown to modulate visceral nociception through an interaction with a peripheral, possibly novel, kappa-opioid-like receptor. We used in the present experiments an antisense strategy to further explore the hypothesis that kappa-ORA effects in the colon are produced at a site different from the cloned kappa-opioid receptor (KOR). An antisense oligodeoxynucleotide (ODN) to the cloned rat KOR was administered intrathecally (12.5 microg, twice daily for 4 d) to specifically knock-down the cloned KOR. Efficacy of the KOR antisense ODN treatment was behaviorally evaluated by assessing the antinociceptive effects of peripherally administered kappa- (EMD 61, 753 and U 69,593), mu- (DAMGO) and delta- (deltorphin) ORAs in the formalin test. Intrathecal antisense, but not mismatch ODN blocked the actions of EMD 61,753 and U 69,593 without affecting the actions of DAMGO or deltorphin; a complete recovery of antinociceptive actions of the kappa-ORA EMD 61,753 was observed 10 d after the termination of antisense ODN treatment. In contrast, the ability of EMD 61,753 to dose-dependently attenuate responses of pelvic nerve afferent fibers to noxious colonic distension was unaffected in the same rats in which the antisense ODN effectively knocked-down the KOR as assessed in the formalin test. Additionally, Western blot analysis demonstrated a significant downregulation of KOR protein in the L4-S1 dorsal root ganglia of antisense, but not mismatch ODN-treated rats. The present results support the existence of a non-kappa-opioid receptor site of action localized in the colon.

Acetamides↗

Visceral pain.

Visceral pain, although different from somatic pain in several important features, is not as widely researched and consequently our knowledge of neurophysiologic mechanisms as well as clinical management of visceral pain states remains unsatisfactory. Several recent studies have employed different visceral pain animal models to provide insight into the peripheral and central nervous system mechanisms underlying pain originating from the urinary bladder, ureter, and gastrointestinal tract. The effects of opioid and nonopioid drugs in these models have also been evaluated and are reviewed in this article. The importance of anatomic pathways relaying pain sensation in the central nervous system, particularly the newly described dorsal column pathway, is also discussed. In human subjects, new techniques like positron emission tomography are now being used to better understand visceral pain perception. Such findings deriving from basic animal research and human studies summarized in the present overview lead to a better understanding of visceral pain states and may be helpful in developing better treatment strategies to combat visceral pain states in the clinical setting.

Afferent Pathways↗

Analysis of immune responses against T- and B-cell epitopes from Plasmodium falciparum liver-stage antigen 1 in rodent malaria models and malaria-exposed human subjects in India.

Liver-stage antigen 1 (LSA-1) is a potential vaccine candidate against preerythrocytic stages of malaria. We report here the immunogenicity of linear synthetic constructs delineated as T(H)-cell determinants from the nonrepeat regions of Plasmodium falciparum LSA-1 in murine models and human subjects from areas where malaria is endemic in Rajasthan State, India. Seven peptide constructs (LS1.1 to LS1.7) corresponding to predicted T-cell sites from both the N- and C-terminal regions and peptide LS1R from a repeat region of PfLSA-1 were synthesized to analyze the cellular immune responses. These linear peptides were also tested for humoral responses in order to determine if there were any overlapping B-cell epitopes in the predicted T-cell sites. Most peptides induced cellular responses in peptide-immunized BALB/c and C57BL/6 mice as measured by proliferation and cytokine analysis. Cross-reactive T-cell recognition of P. falciparum-based peptides in Plasmodium berghei-immune animals was evaluated, but only one peptide, LS1.2 (amino acids 1742 to 1760) triggered T-cell proliferation and interleukin-2 and gamma interferon secretion in P. berghei-immune splenocytes of BALB/c and C57BL/6 mice as well as in Thamnomys gazellae (natural host of P. berghei ANKA). In an enzyme-linked immunosorbent assay with the peptides, only one peptide, LS1.1, was recognized by anti-P. berghei liver-stage serum. Three peptides (LS1. 1, LS1.2, and LS1.3) of the eight peptides tested in this study were recognized by a relatively large percentage of P. falciparum-exposed human subjects; the reactivities ranged from approximately 45% for LS1.3 to approximately 60% for LS1.1 and LS1.2. Interestingly, all of the eight putative T-cell determinants were also recognized by the sera collected from malaria patients, although the response was variable in nature. These T(H)- and B-cell epitopes may be of potential value for preerythrocytic antigen-based malaria subunit vaccine formulations.

Adolescent↗

Induction of protective immune responses by immunization with linear multiepitope peptides based on conserved sequences from Plasmodium falciparum antigens.

A cysteine-containing peptide motif, EWSPCSVTCG, is found highly conserved in the circumsporozoite protein (CSP) and the thrombospondin-related anonymous protein (TRAP) of all the Plasmodium species analyzed so far and has been shown to be crucially involved in the sporozoite invasion of hepatocytes. We have recently shown that peptide sequences containing this motif, and also the antibodies raised against the motif, inhibit the merozoite invasion of erythrocytes. However, during natural infection, and upon immunization with recombinant CSP, this motif represents a cryptic epitope. Here we present the results of immunization studies with two linear multiepitopic constructs, a 60-residue (P60) and a 32-residue (P32) peptide, containing the conserved motif sequence. Both the peptides per se generated high levels of specific antibodies in BALB/c mice. P32 was found to be genetically restricted to H-2(d) and H-2(b) haplotypes of mice, whereas P60 was found to be immunogenic in five different strains of mice. The antibody response was predominantly targeted to the otherwise cryptic, conserved motif sequence in P60. Anti-P60 antibodies specifically stained the asexual blood stages of Plasmodium falciparum and Plasmodium yoelii in an immunofluorescence assay, recognized a 60- to 65-kDa parasite protein in an immunoblot assay, and blocked P. falciparum merozoite invasion of erythrocytes in a dose-dependent manner. Immunization with P60 also induced significant levels of the cytokines interleukin-2 (IL-2), IL-4, and gamma interferon in BALB/c mice. Moreover, >60% of mice immunized with P60 survived a heterologous challenge infection with a lethal strain of P. yoelii. These results indicate that appropriate medium-sized synthetic peptides might prove useful in generating specific immune responses to an otherwise cryptic but critical and putatively protective epitope in an antigen and could form part of a multicomponent malaria vaccine.

Amino Acid Sequence↗

Peak expiratory flow rate of carpet weaving children.

OBJECTIVE: To assess the adverse influence of carpet weaving on lung functions and the nurtritional status of children employed in such factories. DESIGN: Comparison of the peak expiratory flow rate (PEFR) of the study group with controls of similar socio-economic status and correlate it with anthropometric values. SETTING: Field study. SUBJECTS: One hundred and ten boys, 6-15 years of age engaged in 23 carpet weaving factories of Jaipur city. OUTCOME MEASURES: Linear regression analysis using age, height and weight as independent variables and PEFR as the dependent variable. RESULTS: PEFR of carpet weaving children were significantly lower (p < 0.05) than controls for all except 6-7 years group. The height, weight and chest circumference of these children were also lower (p < 0.05). PEFR did not show significant difference when children were grouped according to their height. CONCLUSIONS: Children working in carpet weaving factories are shorter and lighter compared to normal school going children. As a consequence of the growth retardation, their PEFR values were also lower as compared to normal children.

Adolescent↗

Health status of carpet weaving children.

A cross-sectional study was undertaken to determine the health status of children engaged in carpet weaving factories of Jaipur City. Two hundred and ninety school going boys of similar socio-economic status served as controls. A higher prevalence of signs of nutritional deficiencies was observed in carpet weaving children. Analysis of the presenting complaints and the illness suffered in the past six months also revealed a significantly higher morbidity in these children. A statistically significant difference was also observed in anthropometric measurements of the two groups.

Adolescent↗