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Biomedical subjects

S Bhattacharya

Publications and source records attributed to S Bhattacharya.

At least 127 records · Page 7Linked to original sources
PubMed2001

A study report of 174 units of placental umbilical cord whole blood transfusion in 62 patients as a rich source of fetal hemoglobin supply in different indications of blood transfusion.

BACKGROUND: In the animal kingdom, even herbivorous animals swallow the placenta after the birth of the baby (for example, the cow). In the human system, we do not know about the proper utilization of the placenta and membranes although there are suggestions regarding this on the basis of research on placental umbilical cord blood stem cells as an alternative to bone marrow transplantation. In this present series of placental umbilical cord whole blood transfusions, we wanted to examine the safety aspect of other components of cord blood transfusion, e.g., fetal RBC, growth factors and cytokine filled plasma, etc., in different indications of blood transfusion, from the pediatric to the geriatric age group, in malignant and non-malignant disorders affecting our patients. METHODS: One hundred and seventy-four units of umbilical cord whole blood were collected aseptically from the umbilical vein after caesarean section in standard pediatric blood transfusion bags, after the removal of the baby from the operative field and after confirming the stable condition of the mother. The volume of cord blood varied from 50 ml to 140 ml with a mean of 86 ml+/-16 ml. RESULTS AND ANALYSIS: The cord blood was transfused immediately (within three days of collection) to 62 patients from nine years to 78 years of age, of whom 32 were suffering from varying stages and grades of malignancy from 1 April 1999 till date i.e., 11 Aug 2000, after obtaining adequate consent and following the precautions of standard blood transfusion protocol. The remaining 30 patients included patients suffering from thalassemia major, aplastic anemia, systemic lupus erythematosus, chronic renal failure, rheumatoid arthritis, ankylosing spondylitis and a geriatric group of patients with benign prostatic hypertrophy. All have tolerated the procedure without any immunological or non-immunological reactions. CONCLUSION: On the basis of our experience with 174 units of placental umbilical cord whole blood transfusion in malignant and non-malignant conditions (within three days of collection and preservation at 1-6 degrees C in a refrigerator), we are of the opinion that this is a safe transfusion protocol which takes advantage of the safety of nature's finest biological sieve, i.e., the placenta, as an alternative to adult whole blood transfusion. It also has the advantage of a higher oxygen carrying capacity of fetal hemoglobin in addition to many growth factors and other cytokine filled cord blood plasma along with its hypoantigenicity.

Adolescent↗
PubMed2001

A unique experience with human pre-immune (12 weeks) and hypo-immune (16 weeks) fetal thymus transplant in a vascular subcutaneous axillary fold in patients with advanced cancer: a report of two cases.

BACKGROUND: The successful development of fetal cell/tissue transplantation in adults has resulted in the possibility of eventual therapeutic solutions with a variety of intractable diseases. Umbilical cord whole blood transplantation appears to be safe in the adult system. In severe forms of DiGeorge Syndrome, cultured thymus transplant can help in the reconstitution of the immune condition of the host. Successful fetal tissue transplant in adults has raised the hope of future effective gene transplant and its manipulation prospects to combat many diseases including hemopathies, inborn errors of metabolism, immunodeficiencies and even cancer and AIDS. MATERIALS AND METHOD: Two cases of advanced cancer were treated with fetal (pre-immune 12 weeks and hypo-immune 16 weeks) thymus transplants in subcutaneous vascular axillary folds, which were removed after one month. Thymuses were collected from consenting mothers undergoing hysterotomy and ligation. RESULTS AND ANALYSIS: Patient I was suffering from non-Hodgkins lymphoma (Ann Arbor Stage IV) and was receiving cyclophosphomide, doxorubicin, vincristine and prednisolone after a course of radiotherapy; she developed leucopenia (2.400/cmm), which improved after receiving a 16-week human fetal thymic graft. The leucopenia was eventually over-corrected and the leucocyte count reached 44,000/cmm within a month, which was reversed after the thymus was taken out. Histology of the excised thymic graft showed growth and proliferation without any graft vs. host (GVH) reaction. Patient 2 was suffering from breast duct carcinoma (T4, N2, M0,) with estrogen, progesterone, and epidermal growth factor negative status, and was treated with modified radical mastectomy and axillary clearance followed by chemotherapy with cyclophosphomide, methotrexate and 5-fluorouracil for six cycles. She also received a 12-week-old human fetal thymus at the contra-lateral axilla which was removed after one month. In this case the peripheral leucocyte count did not show appreciable variation as in the first case. However, histology of the excised thymic graft showed growth and proliferation with an appearance of Hassel's corpuscles. CONCLUSION: Pre-immune and hypo-immune human fetal thymic transplant is not rejected in patients suffering from advanced cancer within one month (observation period). Thymic lymphocyte shedding in the correction of leucopenia in the background of non-Hodgkin's lymphoma may have many therapeutic implications.

Adolescent↗
PubMed2001

Wound healing activity of human placental extracts in rats.

AIM: To study wound healing activity of the human placental extract (HPE) in rats. METHODS: Full thickness wounds were inflicted on depilated dorsum of Charles foster rats with 8 mm Acu-punch biopsy. The HPE was applied both at topical and im routes (2.5 mL/kg). Effects were compared on the basis of physical criteria, biochemical criteria, and histopathological study with respect to untreated control, vehicle control (1.5 % benzyl alcohol), and framycetin topical treated groups. RESULTS: Significant lowering of wound size (P<0.05), wound index (P<0.05), and number of days required for complete healing (P<0.01); significant gain in tensile strength (P<0.01); appreciable increase of tissue DNA, total protein, and collagenesis were observed in HPE treated group. CONCLUSION: Human placental extract systematically helps collagenesis leading to potent healing of wounds.

Animals↗
PubMed2001

Boron compounds against human leukemic cells.

Two new boron compoumds, dihydroxy(oxybiguanido) boron (iii) hydrochloride monohydrate (HB) and guanidine biboric acid adduct (GB) were used in this study to observe the antitumor effect. Leukemic blast cells isolated from chronic myeloid leukemia (CML) patients showed significant cell growth inhibition within twentyfour hours. IC50 of GB and HB was 2mg/ml. The metabolically active cells were found to be inhibited by drug treatment as assessed by MTT test. Inhibition of 3H Thymidine incorporation also supported the above result. In this study we investigated the molecular mechanisms by which HB and GB induce apoptosis in immature blast cells.

Apoptosis↗
PubMed2001

High frequency in vitro propagation of Phyllanthus amarus Schum. & Thom. by shoot tip culture.

With the aim of micropropagation of Phyllanthus amarus, an important medicinal herb, shoot tips were cultured in Murashige and Skoog's medium supplemented with kinetin/ BAP singly or in combination with IAA. Growth regulators at lower range (0.1-1.0 mg L(-1)) stimulated direct regeneration of shoots. Kinetin was superior to BAP and kinetin-IAA combination was more suitable than kinetin alone. About 15 shoots were yielded per explant after 30 days of culture in the medium containing kinetin and IAA both at 0.1mg L(-1). The cluster of proliferated shoots elongated and rooted simultaneously under the same treatment following another subculture, thus shortening the total time schedule of micropropagation. Shoot tips of regenerated shoots were continuously used to regenerate new shoots with periodic transfer to fresh medium resulting in a steady supply of normal, healthy plants without any deviation in the production rate during a continuous one year culture. Micropropagated plants were successfully established in soil with high survivality (80%).

Botany↗
PubMed2001

Bilateral ovarian hydatid disease--an unusual case.

Hydatid disease is caused by parasitic tapeworm Echinococcus. The larval stage of this parasite can thrive in many parts of the body, most frequently in the liver. Primary ovarian location is very rare. In our case the patient had bilateral ovarian cysts which on histopathological study was found to be hydatid cysts. Moreover one of the cysts was multilocular which is also unusual.

Adult↗
PubMed2000

Instabilities and disorder-driven first-order transition of the vortex lattice

Transport studies in a Corbino disk suggest that the Bragg glass phase undergoes a first-order transition into a disordered solid. This transition shows sharp reentrant behavior at low fields. In contrast, in the conventional strip configuration, the phase transition is obscured by the injection of the disordered vortices through the sample edges, which results in the commonly observed vortex instabilities and smearing of the peak effect in NbSe2 crystals. These features are found to be absent in the Corbino geometry in which the circulating vortices do not cross the sample edges.

Journal Article↗
PubMed2000

Characterization of the interaction of calcyclin (S100A6) and calcyclin-binding protein.

Calcyclin (S100A6) is an S100 calcium-binding protein whose expression is up-regulated in proliferating and differentiating cells. A novel 30-kDa protein exhibiting calcium-dependent calcyclin-binding (calcyclin-binding protein, CacyBP) had been identified, purified, and cloned previously (Filipek, A., and Kuznicki, J. (1998) J. Neurochem. 70, 1793-1798). Here, we have defined the calcyclin binding region using limited proteolysis and a set of deletion mutants of CacyBP. A fragment encompassing residues 178-229 (CacyBP-(178-229)) was capable of full binding to calcyclin. CacyBP-(178-229) was expressed in Escherichia coli as a glutathione S-transferase fusion protein and purified. The protein fragment cleaved from the glutathione S-transferase fusion protein was shown by CD to contain 5% alpha-helix, 15% beta -sheet, and 81% random coil. Fluorescence spectroscopy was used to determine calcyclin dissociation constants of 0.96 and 1.2 microm for intact CacyBP and CacyBP-(178-229), respectively, indicating that the fragment can be used for characterization of calcyclin-CacyBP interactions. NMR analysis of CacyBP-(178-229) binding-induced changes in the chemical shifts of (15)N-enriched calcyclin revealed that CacyBP binding occurs at a discrete site on calcyclin with micromolar affinity.

Amino Acid Sequence↗
PubMed2000

Interactions between cholesterol and lipids in bilayer membranes. Role of lipid headgroup and hydrocarbon chain-backbone linkage.

We have employed four lipids in the present study, of which two are cationic and two bear phosphatidylcholine (PC) headgroups. Unlike dipalmitoylphosphatidylcholine, the other lipids employed herein do not have any ester linkage between the hydrocarbon chains and the respective lipid backbones. Small unilamellar vesicles formed from each of the PC and cationic lipids with or without varying amounts of cholesterol have been examined using the steady-state fluorescence anisotropy method as a function of temperature. The anisotropy data clearly indicate that the order in the lipid bilayer packing is strongly affected upon inclusion of cholesterol. This effect is similar irrespective of the electrostatic character of the lipid employed. The influence of cholesterol inclusion on multi-lamellar lipid dispersions has also been examined by 1H-nuclear magnetic resonance spectroscopy above the phase transition temperatures. With all the lipids, the line widths of (CH2)n protons of hydrocarbon chains in the NMR spectra respond to the addition of cholesterol to membranes. The influence on the bilayer widths of various lipids upon inclusion of cholesterol was determined from X-ray diffraction studies of the cast films of the lipid-cholesterol coaggregates in water. The effect of cholesterol on the efflux rates of entrapped carboxyfluorescein (CF) from the phospholipid vesicles was determined. Upon incremental incorporation of cholesterol into the phospholipid vesicles, the CF leakage rates were progressively reduced. Independent experiments measuring transmembrane OH- ion permeation rates from cholesterol-doped cationic lipid vesicles using entrapped dye riboflavin also demonstrated that the addition of cholesterol into the cationic lipid vesicles reduced the leakage rates irrespective of lipid molecular structure. It was found that the cholesterol induced changes on the membrane properties such as lipid order, linewidth broadening, efflux rates, bilayer widths, etc., did not depend on the ability of the lipids to participate in the hydrogen bonding interactions with the 3beta-OH of cholesterol. These findings emphasize the importance of hydrophobic interaction between lipid and cholesterol and demonstrate that it is not necessary to explain the observed cholesterol induced effects on the basis of the presence of hydrogen bonding between the 3beta-OH of cholesterol and the lipid chain-backbone linkage region or headgroup region.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

Nature of linkage between the cationic headgroup and cholesteryl skeleton controls gene transfection efficiency.

Three novel cationic cholesterol derivatives with different modes of linkage between the cationic headgroup and the cholesteryl backbone have been synthesized and used as mixtures with 1, 2-dioleoyl-L-alpha-glycero-3-phosphatidyl ethanolamine (DOPE) for liposome-mediated gene transfection. A pronounced improvement in gene transfer efficiency was observed when the cationic center was appended to the cholesteryl backbone using an ether linkage as opposed to when the linkages were based on either ester or urethane groups. Amphiphiles with ether links such as cholest-5-en-3beta-oxyethane-N,N,N-trimethyl ammonium bromide (2) and cholest-5-en-3beta-oxyethane-N,N-dimethyl-N-2-hydroxyethyl ammonium bromide (3) showed transfection efficiencies considerably greater than commercially available gene transfer reagents. Notably, the transfection ability of 2 with DOPE in the presence of serum was significantly greater than Lipofectamine((R)) and Lipofectin((R)). Interestingly, 3 did not require the helper lipid DOPE for transfection. This suggests that these newly described cholesterol-based amphiphiles should be very promising in liposome-mediated gene transfection. The advantage that the ether linkage possesses would be important in the design of newer, more efficient cholesterol-based delivery reagents.

Animals↗
PubMed2000

The genome of Entamoeba histolytica.

Estimation of genome size of Entamoeba histolytica by different methods has failed to give comparable values due to the inherent complexities of the organism, such as the uncertain level of ploidy, presence of multinucleated cells and a poorly demarcated cell division cycle. The genome of E. histolytica has a low G+C content (22.4%), and is composed of both linear chromosomes and a number of circular plasmid-like molecules. The rRNA genes are located exclusively on some of the circular DNAs. Karyotype analysis by pulsed field gel electrophoresis suggests the presence of 14 conserved linkage groups and an extensive size variation between homologous chromosomes from different isolates. Several repeat families have been identified, some of which have been shown to be present in all the electrophoretically separated chromosomes. The typical nucleosomal structure has not been demonstrated, though most of the histone genes have been identified. Most Entamoeba genes lack introns, have short 3' and 5' untranslated regions, and are tightly packed. Promoter analysis revealed the presence of three conserved motifs and several upstream regulatory elements. Unlike typical eukaryotes, the transcription of protein coding genes is alpha-amanitin resistant. Expressed Sequence Tag analysis has identified a group of highly abundant polyadenylated RNAs which are unlikely to be translated. The Expressed Sequence Tag approach has also helped identify several important genes which encode proteins that may be involved in different biochemical pathways, signal transduction mechanisms and organellar functions.

Animals↗
PubMed2000

Unusual coordination mode of thiosemicarbazone ligands. A search for the origin.

Twelve mixed-ligand thiosemicarbazone complexes of ruthenium and osmium, ten of general formula [M(bpy)2(bztsc-R)]ClO4, (M = Ru, Os; bpy = 2,2'-bipyridine, Hbztsc-R = benzaldehyde thiosemicacbazone) and two of type [M(bpy)2(actsc)]ClO4 (Hactsc = acetonethiosemicarbazone), have been synthesized and characterized. All the complexes are diamagnetic (low-spin d6, S = 0) and in acetonitrile solution show several intense metal-to-ligand charge-transfer (MLCT) transitions in the visible region. Structures of Hbztsc-OMe, [Ru(bpy)2(bztsc-NO2)]ClO4 and [Ru(bpy)2(actsc)]ClO4 have been determined by X-ray crystallography. Benzaldehyde thiosemicarbazone exists in the thione form with the phenyl group trans to the hydrazinic nitrogen. The benzaldehyde thiosemicarbazone ligand coordinates to the metals through the hydrazinic nitrogen and sulfur with a bite angle of approximately 67 degrees, forming a four-membered chelate ring. However, the actsc ligand coordinates through the imine nitrogen and sulfur, forming a five-membered chelate ring with a bite angle of approximately 81 degrees. The difference in coordination modes of two types of thiosemicarbazone ligands, viz., bztsc-R and actsc, appears to result from the difference in steric bulk of the aryl and methyl group trans to the hydrazinic nitrogen. In acetronitrile solution they all show a reversible metal(II)-metal(III) oxidation in the range 0.18-0.58 V vs SCE followed by an irreversible oxidation in the range 1.11-1.60 V vs SCE. Two successive one-electron reductions of the coordinated bipyridine are also observed in the range -1.53 to -1.96 V vs SCE.

Journal Article↗
PubMed2000

alpha(v)beta(3) integrin induces tyrosine phosphorylation-dependent Ca(2+) influx in pulmonary endothelial cells.

The endothelial alpha(v)beta(3) integrin occurs luminally, where its ligation by soluble agents may induce inflammatory signaling. We tested this hypothesis in bovine pulmonary artery endothelial cell monolayers with the use of vitronectin and cross-linking antibodies to ligate and aggregate the integrin. We quantified the endothelial cytosolic Ca(2+) concentration ([Ca(2+)](i)) according to the Fura 2 ratio imaging method in single cells of confluent monolayers. At baseline, endothelial [Ca(2+)](i) levels remained steady at 86 nmol/L for >20 minutes. Cross-linking of the alpha(v)beta(3) integrin through the sequential exposure of monolayers to anti-alpha(v)beta(3) monoclonal antibody LM609 and secondary IgG resulted in a [Ca(2+)](i) increase of 100% above baseline. This increase commenced in <0.5 minute, peaked in <2 minutes, and decayed to baseline in approximately 5 minutes. Similar responses occurred after the addition of vitronectin (400 microg/mL). In contrast, external Ca(2+) depletion blunted the cross-linking-induced [Ca(2+)](i) increase by 60%, a response that was completely inhibited when the monolayers were also pretreated with thapsigargin. Thus, the [Ca(2+)](i) increase was attributable in part to the release of Ca(2+) from endosomal stores but mostly to Ca(2+) influx across the plasma membrane. Induced aggregation of the alpha(v)beta(3) integrin enhanced tyrosine phosphorylation of phospholipase C-gamma1 and increased the accumulation of inositol-1, 4,5-trisphosphate. Genistein, a broad-spectrum tyrosine kinase inhibitor, abrogated both of these effects, as well as the alpha(v)beta(3)-induced [Ca(2+)](i) increases. We conclude that aggregation of the endothelial alpha(v)beta(3) integrin induces a rapid tyrosine phosphorylation-dependent increase in [Ca(2+)](i). This response may subserve the inflammatory role of alpha(v)beta(3) integrin in blood vessels.

Animals↗
PubMed2000

Dynamic instabilities and memory effects in vortex matter

The magnetic flux line lattice in type II superconductors serves as a useful system in which to study condensed matter flow, as its dynamic properties are tunable. Recent studies have shown a number of puzzling phenomena associated with vortex motion, including: low-frequency noise and slow voltage oscillations; a history-dependent dynamic response, and memory of the direction, amplitude duration and frequency of the previously applied current; high vortex mobility for alternating current, but no apparent vortex motion for direct currents; and strong suppression of an a.c. response by small d.c. bias. Taken together, these phenomena are incompatible with current understanding of vortex dynamics. Here we report a generic mechanism that accounts for these observations. Our model, which is derived from investigations of the current distribution across single crystals of NbSe2, is based on a competition between the injection of a disordered vortex phase at the sample edges, and the dynamic annealing of this metastable disorder by the transport current. For an alternating current, only narrow regions near the edges are in the disordered phase, while for d.c. bias, most of the sample is in the disordered phase--preventing vortex motion because of more efficient pinning. The resulting spatial dependence of the disordered vortex system serves as an active memory of the previous history.

Journal Article↗
PubMed2000

DNA binding properties of novel distamycin analogs that lack the leading amide unit at the N-terminus.

First examples of distamycin (Dst) analogs which lack hydrogen bond donor or acceptor groups at the N-terminus have been synthesized. The first molecule of this series, which is a bispyrrole peptide, did not exhibit any detectable binding with double-stranded (ds) DNA. However, all other analogs did bind strongly to AT-rich sequences of ds-DNA, with the binding affinities increasing as a function of the number of repeating pyrrole carboxamide units. These results imply that a hydrogen bond donor or acceptor atom per se at the N-terminus is not a prerequisite for DNA binding in the case of pyrrole carboxamide-based Dst analogs. However, in the absence of H-bond donor or acceptor at the N-terminus, a minimum of three pyrrole carboxamide units is necessary for the onset of DNA binding. Beyond this minimum number, the binding affinity increases as a function of the number of pyrrole units, as a result of the greater availability of hydrogen bonding and van der Waals surface. Experiments with poly[d(G-C)] have shown that the presence of the N-terminus formamide group is not inevitable for GC binding of this class of molecules. The observation that the N-terminus formamide unit can be dispensed with suggests that these molecules, which are much easier to synthesize and functionalize, can be used in place of the conventional analogs of distamycin for the development of novel minor groove binders with extended sequence recognition properties.

Binding Sites↗