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Biomedical subjects

P Nath

Publications and source records attributed to P Nath.

At least 19 recordsLinked to original sources
PubMed2004

Resolution of allergic airways inflammation but persistence of airway smooth muscle proliferation after repeated allergen exposures.

BACKGROUND: Chronic inflammation in asthmatic airways can lead to characteristic airway smooth muscle (ASM) thickening and pathological changes within the airway wall. OBJECTIVE: We investigated the long-term effects of repeated allergen exposure. METHODS: Brown-Norway (BN) rats sensitized to ovalbumin (OVA) were exposed to OVA or saline aerosol every third day on six occasions and studied 24 h, 7 days and 35 days after the final exposure. We measured airway inflammation, ASM cell proliferation (by incorporation of bromodeoxyuridine; BrdU) and bronchial responsiveness to acetylcholine. RESULTS: At 24 h, in OVA-exposed rats, we detected elevated OVA-specific serum IgE, increased numbers of macrophages, eosinophils, lymphocytes and neutrophils in the bronchoalveolar lavage (BAL) fluid and increased numbers of MBP+ (major basic protein) eosinophils and CD2+ T cells within the bronchial submucosa. This coincided with increased numbers of ASM cells expressing BrdU and with bronchial hyper-responsiveness (BHR). At 7 days, BHR was detected in OVA-exposed rats, coincident with increased numbers of macrophages and lymphocytes in BAL fluid together with increased numbers of CD2+ T cells within the bronchial submucosa. This coincided with increased numbers of ASM cells expressing BrdU. By day 35, the number of ASM cells expressing BrdU remained elevated in the absence of cellular infiltration and BHR. CONCLUSION: Repeated OVA-challenge results in persistent ASM cell proliferation in the absence of bronchial inflammation and BHR, which lasts for at least 1 week following cessation of exposure.

Allergens↗
PubMed2001

Upper limits on sparticle masses from g -- 2 and the possibility for discovery of supersymmetry at colliders and in dark matter searches.

We analyze the implications of the new physics effect seen in the g -- 2 Brookhaven measurement and show that if the effect arises from supersymmetry, then the sign of the Higgs mixing parameter mu is determined to be positive in the standard sign convention. Further, analyses within the minimal supergravity model show that the Brookhaven result leads to upper limits on the universal gaugino and scalar masses of m(1/2) < or = 800 GeV and m(0) < or = 1.5 TeV for tan beta < or = 55. Our analysis strongly suggests that supersymmetry via production of sparticles must be found at the CERN Large Hadron Collider. Further, sgn(mu) positive is favorable for the discovery of supersymmetric cold dark matter.

Journal Article↗
PubMed2001

Role of two plasma vitellogenins from Indian major carp (Cirrhinus mrigala) in catfish (Clarias batrachus) vitellogenesis.

Complete vitellogenesis (synthesis and incorporation of vitellogenin, Vg) in the female catfish, Clarias batrachus, during different reproductive phases (preparatory, prespawning, and postspawning) of its annual ovarian cycle is induced by administering heterologous Vg (semipurified; ULT-I and purified; HA-I and HA-II) isolated from the Indian major carp, mrigal (Cirrhinus mrigala). During the prespawning period, ULT-I, which contains both HA-I and HA-II, showed a dose-dependent response in relation to the induction of complete vitellogenesis in female catfish. In the preparatory period, daily treatment with 1 mg of ULT-I for 12 days resulted in an increase in plasma Vg level, ovarian weight, and number of stage-II (vitellogenic) oocytes along with the appearance of stage III (fully formed) yolky oocytes. In the prespawning period, 12-day administration of HA-I at the dose level of 0.5 mg/fish/day enhanced complete vitellogenesis in intact female catfish and induced Vg synthesis in hypophysectomized female catfish, whereas HA-II, at the same dose level, could only stimulate Vg synthesis, indicating their different roles during vitellogenesis. The results so far obtained may be due to the estradiol-17beta contamination in the Vg fractions. Estimation of E(2) in ULT-I, HA-I, and HA-II by E(2) ELISA indicates that HA-II contains only a small amount (106 pg/mg protein). Therefore, daily treatment with 1 mg each of delipidated ULT-I and HA-I for 12 days could synthesize very little Vg, whereas intact ULT-I at the same dose level induced not only a high plasma Vg level but also increased GSI, indicating the importance of lipid in the native molecule for the induction of vitellogenesis. During postspawning period, administration of HA-I (0.5 mg/fish/day for 21 days) to reproductively regressed female catfish pretreated with HA-II (10 microg/fish/day for 7 days) and maintained at a long photoperiod (LD 14:10) and high temperature (30 degrees ), induced complete vitellogenesis.

Animals↗
PubMed2001

A comprehensive system for protein purification and biochemical analysis based on antibodies to c-myc peptide.

The genomics revolution has created a need for increased speed and generality for recombinant protein production systems as well as general methods for conducting biochemical assays with the purified protein products. 9E10 is a well-known high-affinity antibody that has found use in a wide variety of biochemical assays. Here we present a standardized system for purifying proteins with a simple epitope tag based on c-myc peptide using an antibody affinity column. Antibodies with binding parameters suitable for protein purification have been generated and characterized. To purify these antibodies from serum-containing medium without carrying through contaminating immunoglobulin G, a peptide-based purification process was developed. A fluorescence polarization binding assay was developed to characterize the antigen-antibody interaction. Protein purification protocols were optimized using a fluorescein-labeled peptide as a surrogate "protein." Binding and elution parameters were evaluated and optimized and basic operating conditions were defined. Several examples using this procedure for the purification of recombinant proteins are presented demonstrating the generality of the system. In all cases tested, highly pure final products are obtained in good yields. The combination of the antibodies described here and 9E10 allow for almost any biochemical application to be utilized with a single simple peptide tag.

Animals↗
PubMed2001

Acute exposure to environmental tobacco smoke and heart rate variability.

Environmental tobacco smoke (ETS) has been associated with cardiovascular mortality. Pathophysiologic pathways leading from ETS exposure to cardiopulmonary disease are still being explored. Reduced cardiac autonomic function, as measured by heart rate variability (HRV), has been associated with cardiac vulnerability and may represent an important pathophysiologic mechanism linking ETS and risk of cardiac mortality. In this study we evaluated acute ETS exposure in a commercial airport with changes in HRV in 16 adult nonsmokers. We conducted ambulatory electrocardiographic (ECG) monitoring for 8-hr periods while participants alternated 2 hr in nonsmoking and smoking areas. Nicotine and respirable suspended particle concentrations and participants' blood oxygen saturation were also monitored. We calculated time and frequency domain measures of HRV for periods in and out of the smoking area, and we evaluated associations with ETS using comparative statistics and regression modeling. ETS exposure was negatively associated with all measures of HRV. During exposure periods, we observed an average decrement of approximately 12% in the standard deviation of all normal-to-normal heart beat intervals (an estimate of overall HRV). ETS exposures were not associated with mean heart rate or blood oxygen saturation. Altered cardiac autonomic function, assessed by decrements in HRV, is associated with acute exposure to ETS and may be part of the pathophysiologic mechanisms linking ETS exposure and increased cardiac vulnerability.

Adult↗
PubMed2000

Immunohistochemical localization and correlation of p53 and PCNA expression in breast carcinoma.

The object of the present study is to detect the p53 tumour suppressor gene and proliferation cell nuclear antigen (PCNA) expression in breast carcinoma by immunohistochemistry and correlate them with the prognostic parameters. Total 35 cases of primary breast carcinoma were studied and classified histologically. Paraffin sections were stained by using monoclonal antibody D07 for p53 protein and PC-10 for PCNA. Out of 35 cases, 16 (45.7%) were p53 positive and 25 (71.4%) were PCNA positive. The mean PCNA labelling index (PCNA LI +/- SD) was 58.97 +/- 22.72 in tumors positive for both p53+ and PCNA+ while cases negative for p53- and positive for PCNA+ has higher PCNA LI +/- SD (59.24 +/- 18.97). The difference in the two groups was not significant. Most cases were positive for both p53+ and PCNA+ in the age group < 30 with higher mean PCNA LI +/- SD (62.20 +/- 27.13) than in the group > 30 (57.88 +/- 18.47). In the pre-menopausal group 57.1% cases were positive for p53+ with higher PCNA LI +/- SD (59.94 +/- 24.22). Maximum p53 and PCNA positivity was observed in grade III tumors (63.2% and 84.2%). The mean PCNA LI +/- SD was also highest in grade III carcinomas (66.83 +/- 13.97). No significant correlation was found between p53 and PCNA status with morphological type and tumour size except that logistic regression showed a positive correlation with tumour grade. Therefore the present study suggests that both p53 expression and PCNA are markers of poor differentiation in breast cancer.

Adult↗
PubMed1999

Organization and post-transcriptional processing of the psb B operon from chloroplasts of Populus deltoides.

Chloroplast genes are typically organized into polycistronic transcription units that give rise to complex sets of mono- and oligo-cistronic overlapping RNAs through a series of processing steps. The psbB operon contains genes for the PSII (psbB, psbT, psbH) and cytochrome b(6)f (petB and petD) complexes which are needed in different amounts during chloroplast biogenesis. The functional significance of gene organization in this polycistronic unit, containing information for two different complexes, is not known and is of interest. To determine the organization and expression of these complexes, studies have been carried out on crop plants by different groups, but not much information is known about trees. We present the nucleotide sequences of PSII genes and RNA profiles of the genes located in the psbB operon from Populus deltoides, a tree species. Although the gene organization of this operon in P. deltoides is similar to that in other species, a few variations have been observed in the processing scheme.

Amino Acid Sequence↗
PubMed1996

The gene promoter for a bean abscission cellulase is ethylene-induced in transgenic tomato and shows high sequence conservation with a soybean abscission cellulase.

Bean leaf abscission (organ separation) correlates with the de novo accumulation of a pI9.5 cellulase and its mRNA. Overlapping genomic clones encoding the bean abscission cellulase (BAC) were isolated and partially sequenced. In addition, a genomic clone for a soybean abscission cellulase (SAC) was identified and the sequence compared to the BAC genomic sequence. Two 5'-upstream regions are particularly well conserved in the two sequences. Of special interest here is the region between -1 and -200 in the BAC promoter which is highly conserved in the SAC gene. Particle gun bombardment with a BAC promoter construct containing 210 bp of BAC sequence 5' to the transcription start site was sufficient to drive abscission-specific and ethylene and auxin-regulated transient expression in bean. In addition to the transient expression assay, expression was examined in stably transformed tomato. A similar -210 bp BAC promoter construct supported a low level of ethylene-inducible reporter gene expression in tomato leaf abscission zones and adjacent petioles but not in ethylene-treated stem tissue or fruit. Expression from the -210 promoter in tomato abscission zones was inhibited by silver thiosulfate, an ethylene action inhibitor, and was partially inhibited by treatment with auxin.

Base Sequence↗
PubMed1995

Composition and variation in vitamin C, carotenoids, protein, nitrate and oxalate contents in Celosia leaves.

Twenty two lines/accessions belonging to 5 species of Celosia were analysed for their nutritional and antinutritional composition. The nutrient contents, vitamin C varied from 18.8 to 53.6 mg/100 g, carotenoids 9.1 to 15.1 mg/100g, protein 2.1 to 5.9%, while the antinutritional factors, nitrate 0.18 to 0.46% and oxalate 0.98 to 3.93%. Moisture ranged 81 to 89%. Variation of these parameters with leaf position and the amino acids profile of some promising lines was also evaluated.

Ascorbic Acid↗
PubMed1995

Wilms' tumour : a clinicopathologic study with special reference to its morphologic variants.

Twenty five cases of Wilms' tumour were studied with special reference to their morphological variations. Wilms' tumour constituted 7.6% of all the malignant tumours of childhood and 50% of renal malignancies. Male/female ratio was 4:1; the mean age being 3.5 years. Left side was commonly involved (60.9%) center dot bilateral involvement in one case (4.3%). Morphologic study revealed triphasic pattern in 60% cases, biphasic (epithelial + stromal) in 12% and monophasic pattern in 28%. Other features observed were myxomatous degeneration, rhabdomyoblasts, calcification and squamous epithelial pearls seen in 20%, 12%, 8% and 4% respectively.

Adolescent↗