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Biomedical subjects

S Pandey

Publications and source records attributed to S Pandey.

At least 37 records · Page 2Linked to original sources
PubMed2000

Effects of ethanol volume percent on fluorescein-labeled spinach apo- and holocalmodulin.

We report the effects of EtOH volume percent (0-70%) on spinach apo- and holocalmodulin that have been site-selectively labeled with fluorescein (F). In these experiments, calmodulin (CaM) has one F reporter group attached to Cys-26, and this site is located immediately adjacent to one of the four primary Ca(2+)-binding sites (EF hands). The optimum analytical CaM-F sensitivity to Ca2+ occurs between approximately 10 and 30% EtOH. Our results also show that added EtOH causes changes in CaM and these changes are surprisingly different for apo- and holo-CaM. Apo-CaM-F appears to lose one of its two waters of hydration at approximately 20% EtOH and retains one water of hydration between approximately 20 and 70% EtOH. In apo-CaM-F, the semiangle that describes the range over which the fluorescein reporter group can precess remains essentially constant (42 +/- 2 degrees) between 0 and 70% EtOH. This shows that the fluorescein reporter group precessional freedom in apo-CaM-F is not affected significantly by EtOH. Holo-CaM-F also appears to lose one water of hydration at approximately 20-30% EtOH but then appears to denature as the EtOH volume percent increases. The fluorescein reporter group semiangle within holo-CaM-F decreases from 43 +/- 1 degrees in neat aqueous buffer to 36 +/- 1 degrees at 70% EtOH. This shows that holo-CaM-F is less nativelike and the EF hand "closes down" about the fluorescein reporter group in holo-CaM-F as the EtOH volume percent increases.

Apoproteins↗
PubMed2000

Role of polyamines and ethylene as modulators of plant senescence.

Under optimal conditions of growth, senescence, a terminal phase of development, sets in after a certain physiological age. It is a dynamic and closely regulated developmental process which involves an array of changes at both physiological and biochemical levels including gene expression. A large number of biotic and abiotic factors accelerate the process. Convincing evidence suggests the involvement of polyamines (PAs) and ethylene in this process. Although the biosynthetic pathways of both PAs and ethylene are interrelated, S-adenosylmethionine (SAM) being a common precursor, their physiological functions are distinct and at times antagonistic, particularly during leaf and flower senescence and also during fruit ripening. This provides an effective means for regulation of their biosynthesis and also to understand the mechanism by which the balance between the two can be established for manipulating the senescence process. The present article deals with current advances in the knowledge of the interrelationship between ethylene and PAs during senescence which may open up new vistas of investigation for the future.

Adenosylmethionine Decarboxylase↗
PubMed2000

Caspase-dependent and independent cell death in rat hepatoma 5123tc cells.

The objective of this study was to establish whether apoptosis in 5123tc rat hepatoma cells required the caspase-3 dependent pathway. Apoptosis was induced by either growth factor deprivation or treatment with a topoisomerase II inhibitor, VM26, in the absence or presence of caspase inhibitors (DEVD-fmk, z-VAD-fmk and BAF). The results indicated that, although these inhibitors at 10 microM concentration completely blocked caspase-3 activity, they had no effect on either the rate of cell death or on any other apoptotic features, e.g., chromatin condensation, DNA fragmentation, protein cleavage, suggesting that caspase-3 was not required to mediate nuclear destruction in these hepatoma cells. At higher concentrations, up to 100 microM, z-VAD-fmk and BAF, but not DEVD-fmk, did block apoptosis, however, they also caused cell swelling and membrane permeabilization, which are the hallmarks of necrotic cell death. Clearly, high concentrations of these inhibitors must have interfered non-specifically with other metabolic pathways, e.g., z-VAD-fmk at a high concentration blocked protein phosphorylation, and caused cell death by a different mechanism.

Amino Acid Chloromethyl Ketones↗
PubMed2000

Tactual recognition of cognitive stimuli: roles of hemisphere and lobe.

Four groups of focal brain-damaged patients, involving left and right hemisphere damage with or without the involvement of parietal lobe, and a control group of general medical patients, were required (a) dichaptically to perceive two cognitive stimuli (letter letter, figure figure, or letter figure), and (b) haptically match the target stimulus from a set of test stimuli. The number of trials taken to match the target stimulus correctly was the dependent measure. The significant main effect of lobe suggested that the parietal lobe is the primary locus for tactual recognition. All interaction effects involving lobe were nonsignificant. The main effect of hemisphere was nonsignificant, although the interaction of hemisphere x lobe was significant. Left and right hemisphere damaged patients required more trials to recognize "letter" and "figure", respectively.

Adult↗
PubMed2000

Radical aortic replacement employing simultaneous modified Bentall and elephant trunk procedure in Takayasu's arteritis.

A case of Takayasu's arteritis resulting in extensive fusiform aneurysmal dilatation of the entire aorta extending from the aortic root to the abdominal bifurcation associated with aortic regurgitation is described. She underwent successful radical replacement of the aortic root, ascending, transverse arch and proximal part of the descending aorta employing simultaneous modified Bentall and Elephant trunk techniques. During aortic arch replacement the brain was protected by selective antegrade innominate perfusion under moderate hypothermia. A pattern to the best of our knowledge, has not been reported earlier.

Adult↗
PubMed1999

Detection of DNA fragmentation and endonucleases in apoptosis.

DNA degradation during apoptosis is endonuclease mediated and proceeds through an ordered series of stages commencing with the production of large DNA pieces of 300 kb which are then degraded to fragments of 50 kb. The 50-kb fragments are further degraded, in some but not all cells, to smaller pieces (10-40 kb) releasing the small oligonucleosome fragments that are detected as a characteristic DNA ladder on conventional agarose gels. Methodology is presented for the detection of both DNA ladders and the initial stages of DNA fragmentation using pulsed-field gel electrophoresis. We have developed electrophoresis conditions that resolve large fragments of DNA and also retain the smaller fragments on the same gel. Methods for the detection of endonuclease activities responsible for the cleavage of DNA during apoptosis are also presented.

Animals↗
PubMed1999

Cyanoacrylate tissue adhesive augmented tenoplasty: a new surgical procedure for bilateral severe chemical eye burns.

PURPOSE: To report on cyanoacrylate tissue adhesive augmented tenoplasty, a new surgical procedure for bilateral severe chemical eye injuries. METHODS: A 26-year-old man presented with bilateral severe (grade IV) chemical burns involving the eye, periorbital tissues, face, and neck. Despite adequate medical therapy, corneal, limbal, and scleral ulceration progressed in both eyes. Secondary Pseudomonas keratitis necessitated therapeutic penetrating keratoplasty in the right eye. Tenoplasty and glued-on rigid gas permeable contact lens were unsuccessful to arrest progression of corneolimboscleral ulceration in the left eye. We applied n-butyl cyanoacrylate tissue adhesive directly on the ulcerating corneal, limbal, and scleral surface to augment tenoplasty. RESULTS: The left ocular surface healed with resultant massive fibrous tissue proliferation and symblepharon on the nasal side. Ocular surface rehabilitation resulted in a vascularized leukomatous corneal opacity with upper temporal clear cornea. The patient achieved visual acuity of 6/36 in the left eye. CONCLUSION: We suggest that cyanoacrylate tissue adhesive-augmented tenoplasty can be undertaken to preserve ocular integrity and retain visual potential in a severe chemical eye injury.

Adult↗
PubMed1999

Apoptosis-related functional features of the DNaseI-like family of nucleases.

Rat DNaseYb and its human homolog DHP2 are members of a new family of DNaseI-like endonucleases. They contain all the conserved amino acid residues to engage a DNaseI-like catalytic activity and the same molecular mechanisms of DNA hydrolysis. The sequence similarity can be extended to other families of nucleases, such as FEN-1, DNA polymerases, RNaseH and exonuclease III, involved in the ion-dependent hydrolysis of nucleic acids. Their unique features include the NLS signals that place them in the nuclei and a high content of positively charged amino acid residues that results in their high affinity for the substrate. Their properties are consistent with a role in the early stage DNA degradation during apoptosis. The caspase-DFF45/CIDE-CPAN pathway is most likely involved in the second stage of internucleosomal DNA degradation. However, cells express constitutively multiple transcripts encoding DNA degrading enzymes and related molecules, hence they have the molecular diversity to engage the self-destructive pathway appropriate to a given trigger.

Amino Acid Sequence↗
PubMed1999

Development and evaluation of transdermal formulations containing metronidazole and norfloxacin for the treatment of burn wound.

In an attempt for better treatment of partial thickness burn wounds topical ointments containing metronidazole and norfloxacin in different bases were prepared and in vitro release was conducted in phosphate buffer pH 6. It was found that, diffusion of the metronidazole and norfloxacin from the lanolin petrolatum base with 0.25% w/w dimethyl sulfoxide was maximum through hairless rat abdominal skin. Antimicrobial activity of different prepared formulations was found to be more effective both against aerobic and anaerobic bacteria than marketed formulation (1% silver sulfadiazine cream USP). Formulations were significantly effective as compared to that of marketed formulation in wound contraction of the partial thickness burn wound. Histopathological reports supported effectiveness of formulations. It was found that 1% metronidazole and 1% norfloxacin ointments are suitable for treating the partial thickness burn wound.

Administration, Cutaneous↗
PubMed1999

Tactual Recognition of Cognitive Stimuli : Roles of Hemisphere and Lobe.

Four groups of focal brain-damaged patients, involving left and right hemisphere damage with or without the involvement of parietal lobe, and a control group of general medical patients, were required (a) dichaptically to perceive two cognitive stimuli (letter-letter, figure-figure, or letter-figure), and (b) haptically match the target stimulus from a set of test stimuli. The number of trials taken to match the target stimulus correctly was the dependent measure. The significant main effect of lobe suggested that the parietal lobe is the primary locus for tactual recognition. All interaction effects involving lobe were nonsignificant. The main effect of hemisphere was nonsignificant, although the interaction of hemisphere x lobe was significant. Left and right hemisphere damaged patients required more trials to recognize "letter" and "figure", respectively.

Journal Article↗
PubMed1998

Structure and developmental expression of the mouse RGR opsin gene.

PURPOSE: The aim of this study is to isolate and characterize cDNA clones and the genes that encode mouse RPE retinal G protein-coupled receptor (RGR) and to analyze expression of the RGR gene in the developing mouse retina. The conserved amino acid sequences of RGR from various mammals can be compared to the amino acid sequence motif of G protein-coupled receptors. METHODS: Mouse RGR cDNA and gene clones were isolated from a retina cDNA library and 129SV genomic DNA library, respectively. The expression of RGR in the developing C57BL/6J mouse retina was analyzed by immunohistochemical staining with a polyclonal antipeptide antibody. RESULTS: The deduced amino acid sequence of mouse RGR is 78% and 81% identical to that of bovine and human RGR, respectively. The mouse RGR gene is split into seven exons and extends about 11 kb. Two predominant mRNA transcripts, 1.9 and 1.7 kb in length, and a third, relatively faint, 5.5-kb transcript were detected in mouse eye by hybridization to a RGR cDNA probe. Frozen sections of C57BL/6J mouse retina at various stages of development were incubated with a mouse RGR antipeptide antibody. RGR immunoreactivity was first seen at postnatal day 2 (P2) in centrally located RPE cells. From day P6 to P12, there was an increase in the number and intensity of immunoreactive RPE cells in the central and mid-peripheral regions of the retina, while the most peripheral RPE cells were still negative. By day P16, the length of the RPE monolayer was immunoreactive, and staining of the central RPE cells was markedly more intense than at younger ages. CONCLUSIONS: Mouse and human RGR are highly conserved. A gradient of RGR expression in RPE extends from the central to the peripheral retina during development. In reference to the appearance of melanin-positive differentiated RPE cells, the induction of RGR expression is a relatively late event in the maturation of the retina.

Aging↗
PubMed1998

Biochemical evidence for a calmodulin-stimulated calcium-dependent protein kinase in maize.

We provide biochemical evidence for the presence of a Ca2+-dependent calmodulin (CaM)-stimulated protein kinase (CCaMK) from etiolated maize coleoptiles. The kinase, with a molecular mass of 72.3 kDa, was purified to homogeneity by means of ammonium sulphate precipitation, DEAE-Sephacel chromatography. CaM-Sepharose chromatography and gel purification. The purified kinase required 5 mM Mg2+ for activity and had an optimum pH of 7.5. The kinase is a Ca2+-binding protein, as was evident by 45Ca2+-binding and Ca2+ mobility-gel-shift assays. 1 microM Ca2+ stimulated the kinase activity about 12-fold and was further stimulated by the addition of exogenous CaM (approximately 100 nM). Addition of Ca2+ and CaM antagonists decreased the kinase activity. Under in vitro assay conditions the kinase phosphorylated preferentially syntide-2, histone IIIS and casein. Syntide-2 and histone IIIS were phosphorylated at serine residues, showing that the kinase belongs to the serine/threonine family of protein kinases. Autophosphorylation of CCaMK occurred on threonine residue(s) and was Ca2+ dependent. Addition of exogenous CaM had no effect on autophosphorylation. The properties of the maize kinase suggests that it is a CCaMK that shows dual stimulation with Ca2+ and CaM for substrate phosphorylation and only Ca2+ requirement for autophosphorylation. Antibodies raised against the kinase cross-reacted with maize total proteins to give a single band of 72 kDa and precipitated substrate (syntide-2 and histone IIIS)-phosphorylation and autophosphorylation activities in a specific manner. Localisation studies with antibodies showed that the kinase is ubiquitous.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1998

DNaseY: a rat DNaseI-like gene coding for a constitutively expressed chromatin-bound endonuclease.

A rat gene, designated DNaseY, encoding a 36 kDa endonuclease was identified and cloned. Sequence analysis of the cDNA showed it to be the rat homologue of human DNAS1L3. The DNaseY gene product had 42% identity to DNaseI, including conserved critical active site residues, the essential disulfide bridge, the calcium binding domain, and a signal peptide, as well as 2 of the 3 signature boxes. Significantly, DNaseY had 2 nuclear localization signals and was more basic (pI 9.5) than DNaseI (pI 4.8). The DNaseY gene contained a number of exons similar to that of DNaseI, separated by much larger introns, resulting in a gene of >17 kb compared to <4 kb gene of DNaseI. The 36 kDa DNaseY gene product was catalytically inactive but was converted to an active 33 kDa endonuclease following processing of the hydrophobic signal peptide. Antibody generated against peptides representing the predicted amino acid sequence of DNaseY cross-reacted with a 33 kDa nuclear protein which possessed endonucleolytic activity. The enzyme was active over a broad pH range (optimum pH 7-8), was Ca2+/Mg2+-dependent, was inhibited by Zn2+, and was capable of both single- and double-stranded DNA cleavage, producing DNA fragments with 3'-OH ends. Furthermore, the DNaseY gene was expressed constitutively in all cells and tissues tested, but it was not transcriptionally up-regulated in apoptotic cells. All these features were consistent with a role in the early stages of apoptotic DNA fragmentation.

Amino Acid Sequence↗
PubMed1998

Small aortic annulus: a functional definition.

BACKGROUND & OBJECTIVE: Small aortic annulus is conventionally associated with poor outcome after aortic valve replacement (AVR). Contrarily, several patients have excellent follow-up results after AVR with 19, 20 or 21 size Medtronic Hall (MH) or Sorin Carbocast (SC) prostheses. This disparity prompted a relook at the semantics of a small aortic annulus. METHODS: Available survivors of isolated AVR with #19, #20 or #21 prostheses - 13 with 19 SC or 20 MH valves (Group A) and 29 with 21 SC or MH valves (Group B) were studied. Disparity between actually implanted prostheses versus predicted prosthetic size (tissue annulus diameter) was analysed according to nomograms of Rowlatt et al, NIH Plehn, Kishimoto formula and Sievers composite criteria. Preoperative and follow-up echocardiographic assessments were used for hemodynamic and prosthetic function indices. RESULTS: Both groups were similar in age, height, weight, BSA, BMI, mean NYHA class, CTR, preoperative peak gradient (PG) (92. 0 +/- 29.55 vs 102.88 +/- 33.65), mean gradient (MG) (56.8 +/- 24.6 vs 61.55 +/- 16.56), LVEDD (50.75 +/- 10.92 vs 56.0 +/- 13.5), LVESD (34.37 +/- 13.32 vs 38.52 +/- 13.85) and LVEF (67.5 +/- 12.5 vs 63.9 +/- 14.3). By developmental indices of Rowlatt et al. and NIH, no valve annulus could be designated as narrow. By Sievers composite nomogram all implanted valves were undersized by echocardiographic parameters, in normal range by angiographic criteria and oversized by anatomic autopsy data. Implanted valves in both groups were bigger than Plehn-predicted size (18.16 +/- 1.48 in GrA, 19.46 +/- 1. 10 in GrB). Valve size indices (VSI) (GrA 16.16 +/- 2.85 GrB 14.24 +/- 1.64) and geometric orifice area indices (VAI: valve area index) (GrA 1.50 +/- 0.28 vs 1.41 +/- 0.19) and postoperative rest PG (GrA 47.2 +/- 18.6 GrB 33.8 +/- 9.9) and MG (GrA 27.2 +/- 12.9 vs 19.0 +/- 9.9) were acceptable. LVEDD and LVESD regressed in both groups. LV mass indices regressed from 218.56 +/- 100.85 to 128.17 +/- 27.7 in GrA and 238.94 +/- 102.5 to 134.22 +/- 34.72 in GrB. Performance indices of implanted valves and postoperative aortic valve resistances were correlative. CONCLUSIONS: The size of the implanted prostheses per se does not denote narrowness. Patient-prosthesis mismatch may be considered if predicted prosthesis has VSI <12 mm/m2, VAI <1.31 cm2/m2 or prosthesis orifice diameter <19 mm which may indicate annular enlargement.

Adult↗
PubMed1997

Involvement of host factors in transcription from baculovirus very late promoters -- a review.

The baculovirus expression vector system has emerged as the system of choice for the expression of a number of heterologous genes of both prokaryotic and eukaryotic origin. This system utilizes the baculovirus very late, hyperactive polyhedrin and p10 promoters to drive the transcription of foreign genes. Regulation of transcription from these promoters is presently not well understood even though a number of viral gene products that may be important for transcription have been identified. Fresh insight into host-virus interactions during baculovirus pathogenesis is now offered by the identification of insect host factors that interact with transcriptionally essential motifs of these promoters as well as cis-acting enhancer-like elements upstream from the promoter.

Base Sequence↗
PubMed1997

Identification of a novel 97 kDa endonuclease capable of internucleosomal DNA cleavage.

The two steps of DNA digestion seen in apoptotic cells were recreated in nuclei isolated from 5123tc rat hepatoma cells. The initial DNA cleavage, into high molecular weight fragments (300-50 kb), was stimulated by magnesium ions alone, whereas the second step required both calcium and magnesium ions and produced the ladder of oligonucleosomes. Endonucleolytic activities involved in both steps of DNA cleavage could be separated under appropriate conditions since the magnesium-modulated activity was tightly bound to the chromatin whereas the calcium/magnesium-dependent internucleosomal cleaving activity was easily extractable with a low ionic strength buffer. This calcium/ magnesium-dependent activity was attributed to a novel 97 kDa endonuclease which was also activated by manganese and cobalt and inhibited by millimolar concentrations of zinc, consistent with the properties ascribed to the apoptotic endonuclease. Furthermore, this activity became resistant to extraction with a low salt buffer in nuclei of apoptotic cells. Isoelectrofocusing revealed that the p97 protein existed in multiple forms of different isoelectric points (pI range 4.6-5.0), indicative of its postranslational modification. The p97 enzyme was present constitutively in a variety of cultured cells and rat tissues. It was active over a broad range of pH (6-9), but it was inactivated by reducing agents. In vitro, it displayed both endo- and exonucleolytic activities, and it was capable of both single- and double-stranded DNA cleavage. Rabbit polyclonal anti-p97 antibodies were generated and used to further distinguish this protein from other known cellular nucleases, namely, DNases I and II.

Animals↗
PubMed1997

Absorption of ciprofloxacin and norfloxacin when administered as niosome-encapsulated inclusion complexes.

An attempt has been made to design suitable niosome-encapsulated drug delivery system for ciprofloxacin and norfloxacin. Encapsulation of ciprofloxacin and norfloxacin in niosomes was investigated and the nasal and intestinal absorption of the products studied. More than 80% of the drugs were successfully encapsulated to give products with sustained release characteristics. Encapsulation in niosomes also improved the stability of the antibacterial compounds. Although the systemic availability of these niosome-encapsulated antibacterial compounds was not increased after nasal administration, intestinal absorption was significantly higher in comparison with that of plain inclusion complexes.

Absorption↗