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Biomedical subjects

S Ghosh

Publications and source records attributed to S Ghosh.

At least 451 records · Page 25Linked to original sources
PubMed1997

Identification of motor areas of the cat cerebral cortex based on studies of cortical stimulation and corticospinal connections.

The location and topography of motor areas in the cat cerebral cortex were studied by electrical stimulation of the cortex in five animals, and by the injection of retrograde tracers into the spinal cord of four animals. Movements evoked by intracortical microstimulation (ICMS) of the anterior, posterior and lateral sigmoid gyri, both banks of the cruciate sulcus and the dorsal bank of the presylvian sulcus were observed in anaesthetized cats. Fluorescent tracers (Fast Blue and/or Diamadino Yellow) were injected into the lateral funiculus in the second cervical segment, into the gray matter of cervical segments C3-T1 and/or into the gray matter of lumbar segments L2-S1. Contraction of the contralateral forelimb, hindlimb or facial muscles was observed following electrical stimulation of several cytoarchitectonic areas: 4 gamma, 4 delta, 6a alpha, 6a gamma, and 3a. These findings suggested representations of contralateral forelimb and hindlimb movements in areas 4 gamma and 4 delta, and of the contralateral forelimb muscles in areas 6a alpha and 6a gamma. Corticospinal neurons were located in all the above cytoarchitectonic areas as well as in areas 3b, 1, 2, 2pri, and 5. Large numbers of neurons were labeled in areas 4 gamma and 4 delta, and moderate labeling was observed in areas 6a gamma and 6a alpha. Corticospinal neurons projecting to cervical and lumbar segments were located in areas 4 gamma and 4 delta, while those projecting only to cervical segments were detected in areas 6a alpha and 6a gamma. Based on these findings it is proposed that within the motor cortex of the cat there are representations of limb movements in several cytoarchitectonic subdivisions. Many of these representations may be candidate secondary motor areas.

Animals↗
PubMed1997

Modulation of cerebral calcium homeostasis in rats by angiotensin II in vivo.

The uptake of 45Ca2+ by different regions of the brain was determined in anaesthetised rat after infusing angiotensin II (AII; 14 micrograms in 1 ml) through the carotid artery. The control animals (C) were infused with physiological saline. 45Ca2+ was injected in the tail vein 2 min after the infusion of AII or saline. Plasma radioactivity was monitored until euthanasia at different times post injection when the cerebral uptake of 45Ca2+ was determined. While the plasma turnover of 45Ca2+ was similar in AII and C animals, the uptake was markedly higher in AII vs. C at the different brain sites at all times. Kinetic analysis suggested that AII induced a short term increase in Ca2+ transport across the blood-brain barrier and also in the cellular uptake. The effect of AII was receptor mediated being abolished by saralasin, an AII antagonist, and appeared to be at least in part independent of its pressor effect.

Angiotensin II↗
PubMed1997

Interaction of cholecystokinin and somatostatin with a selective mu-opioid agonist and mu- and kappa-antagonists in thermoregulation.

We examined the effects of intracerebroventricular (i.c.v.) injections of cholecystokinin-octapeptide (CCK-8) and somatostatin (SST) and the interactions of these neuropeptides with the selective opioid antagonists, CTAP (mu) and nor-BNI (kappa) and the mu-agonist, PL017, on body temperature (Tb) of the rat at normal ambient temperature (21 +/- 0.5 degrees C). CCK-8 produced short-lasting (15-60 min), dose-related increases in Tb in a dose range of 20 to 900 ng but did not change the Tb at lower doses (0.1-2 ng). Lower doses of SST (1 and 2 micrograms) produced hyperthermia (30-60 min) and a higher dose of SST (10 micrograms) caused hypothermia (30-45 min). PL017 (1 microgram, i.c.v.), alone and in combination with CCK-8, produced hyperthermia. The CCK-8 (300 ng)-induced hyperthermia was blocked by pretreatment of rats with CTAP (1 microgram, i.c.v.), suggesting that the higher doses of CCK-8 increase Tb through the interaction with mu-receptors or the enhancement of release of endogenous opioids acting on the mu-receptor. The hyperthermia elicited by a lower dose of SST (1 microgram) was prevented by pretreatment with CTAP but not with nor-BNI (1 microgram, i.c.v.). Pretreatment with nor-BNI blocked the higher dose (10 micrograms) of SST-induced hypothermia. PL017 or CTAP did not prevent the hypothermic effect of that dose of SST. These results indicate that a lower dose of SST (1 microgram) stimulates the mu-receptor (directly or indirectly) and a higher dose (10 micrograms) interacts with the kappa-receptor in regulation of Tb. Thus, the effects of both CCK-8 and SST on Tb appear to involve the endogenous opioid system.

Animals↗
PubMed1997

Expression of regeneration-associated cytoskeletal proteins reveals differences and similarities between regenerating organs.

The unique events which allow regeneration of an entire organ to occur are formation of a specialized wound epidermis and accumulation of progenitor cells (blastemal cells) at the amputated surface to form a blastema. In order to identify some of the molecular events underlying the early stages of the regenerative process which are either common to different systems or specific to one of them, we have investigated whether molecules which are induced in limb blastemas are also expressed in skin repair and during regeneration of other complex body structures (lower jaws, upper jaws, and tails). In addition, we have addressed the issue of the identity of progenitor cells during jaw development and regeneration by analyzing the expression of limb blastemal markers in the developing head and face. We have focused on cytoskeletal components, and particularly on the epidermal keratin NvKII, the simple epithelial keratins 8 and 18 and 22/18, because they are among the few molecules which have been shown to be associated with regeneration in the limb and may play significant roles in various developmental processes. Some important findings emerge from this study: 1) Expression of the epidermal keratin NvKII, unlike that of its mammalian homologue K6, is not simply induced in response to wounding, but is associated with regeneration of specific organs. In fact, NvKII is expressed in regenerating limbs and tails, but not in upper or in lower jaw regenerates, demonstrating the existence of molecular differences in the composition of the wound epidermis in these systems. This, together with the fact that NvKII mRNA is regulated by retinoic acid, which differentially affects patterning of limbs and jaws, argues for distinct inductive abilities of the wound epidermis in different organs. 2) In contrast to the differential expression of the epidermal keratin NvKII, the regeneration-associated cytoskeletal molecules identified in limb blastemal cells are expressed in a similar fashion in jaw and tail blastemas. Therefore, it appears that similar cellular events lead to the establishment of an actively proliferating population of progenitor cells from the stump of different organs. Finally, the mesenchyme of the facial rudiments, unlike that of developing limb buds, expresses simple epithelial keratins. Thus, it appears that mesenchymal progenitor cells of developing and regenerating jaws are alike in regard to their intermediate filament content, and this may be related to nerve-dependent growth control of progenitor cells in different developing and regenerating systems.

Animals↗
PubMed1997

Power of variance component linkage analysis to detect epistasis.

Variance component methods are now being used in linkage analysis to detect genes influencing complex diseases. These methods are easily extended to allow for simultaneous estimation of both the additive effects of multiple loci on phenotypic variation (conditional oligogenic analysis) and the additive interaction (epistatic) effects among loci. We performed linkage analyses on 200 of the simulated replicates in order to evaluate the power to detect the main effects of MG1 and MG2 on Q1 as well as their interaction effects. The power to detect the main effect of MG1 was moderately good, although the power to detect MG2 and the MG1 x MG2 interaction was poor.

Analysis of Variance↗
PubMed1997

Secondary and tertiary structural changes in gamma delta resolvase: comparison of the wild-type enzyme, the I110R mutant, and the C-terminal DNA binding domain in solution.

gamma delta Resolvase is a site-specific DNA recombinase (M(r) 20.5 kDa) in Escherichia coli that shares homology with a family of bacterial resolvases and invertases. We have characterized the secondary and tertiary structural behavior of the cloned DNA binding domain (DBD) and a dimerization defective mutant in solution. Low-salt conditions were found to destabilize the tertiary structure of the DBD dramatically, with concomitant changes in the secondary structure that were localized near the hinge regions between the helices. The molten tertiary fold appears to contribute significantly to productive DNA interactions and supports a mechanism of DNA-induced folding of the tertiary structure, a process that enables the DBD to adapt in conformation for each of the three imperfect palindromic sites. At high salt concentrations, the monomeric I110R resolvase shows a minimal perturbation to the three helices of the DBD structure and changes in the linker segment in comparison to the cloned DBD containing the linker. Comparative analysis of the NMR spectra suggest that the I110R mutant contains a folded catalytic core of approximately 60 residues and that the segment from residues 100 to 149 are devoid of regular structure in the I110R resolvase. No increase in the helicity of the linker region of I110R resolvase occurs on binding DNA. These results support a subunit rotation model of strand exchange that involves the partial unfolding of the catalytic domains.

Ammonium Sulfate↗
PubMed1997

Monoclonal antibody raised against human mitotic cyclin B1, identifies cyclin B-like mitotic proteins in synchronized onion (Allium cepa L.) root meristem.

Cyclin B-like mitotic proteins have been detected in synchronized Allium cepa L. root tip cells by using mouse monoclonal anti-cyclin B1 antibody raised against human cyclin B1. Immunoblot shows two closely placed isoforms of cyclin B-like proteins having an apparent molecular weight around 54 kDa. In vivo [35S]-methionine labelling followed by immunoprecipitation and autoradiography indicates that cyclin B-like proteins are mainly synthesized in the G2 phase of the cell cycle and destroyed in late mitosis. Immunoblotting data depict that the level of cyclin B-like proteins reaches the maximum at the late G2 to early M phase; and it becomes degraded in the late hours of mitosis. Moreover, the cyclin B isoforms are stabilized in colchicine-arrested metaphase cells as already reported in animal cells.

Allium↗
PubMed1997

Phospholipase C isoforms delta 1 and delta 3 from human fibroblasts. High-yield expression in Escherichia coli, simple purification, and properties.

Phospholipase C isoforms delta 1 and delta 3 (PLC delta 1 and delta 3) were expressed in Escherichia coli using the cDNA sequences from human fibroblasts. The enzymes were also expressed with the sequence Met-Gly-His6-Ser-Gly-Leu-Phe-Lys-Arg, a hexahistidine sequence followed by a Kex2 protease cleavage site, denoted as "-H6K2," attached to their amino termini. PLC delta 1, PLC delta 1-H6K2, PLC delta 3, PLC delta 3-H6K2 all expressed in highly active form. The H6K2-bearing isoforms were each purified to homogeneity in a single step, with yields of 90-100%, using agarose-iminodiacetic acid-Ni columns and imidazole buffer as eluting agent. Yields in terms of activity increased as the temperature of expression was decreased. Expression at 16 degrees C for 72 h yielded 33 mg of pure PLC delta 1-H6K2 and 13 mg of pure PLC delta 3-H6K2 per liter of culture. Removal of H6K2 from both isoforms with Kex2 protease resulted in little or no loss of activity. Expression of PLC isoforms bearing -H6K2 at the amino terminus resulted in about 12 times more activity than expression of the isoforms lacking -H6K2. PLC delta 3 is much less stable than PLC delta1. Successful purification and storage of PLC delta 3 depends on a suitable stabilizing medium. Both isoforms require 0.3 microM calcium ion for half-maximum activity. The specific activities of the isoforms expressed with and without -H6K2 are the same, as are their calcium saturation curves.

Amino Acid Sequence↗
PubMed1997

cDNA cloning, expression, and rapid purification of a Kunitz-type winged bean chymotrypsin inhibitor.

A 183-residue Kunitz-type winged bean chymotrypsin inhibitor (WbCI), inhibits its cognate protease at a molar ratio of 1:2, instead of the usual ratio of 1:1 common to other members of the family. From the cDNA pool obtained by reverse transcription of the poly(A)+ RNA of the developing winged bean seeds, the structural gene of WbCI has been amplified by PCR using primers designed to delete the 24-residue signal peptide and introduce EcoRI and SalI sites at the ends of the amplified DNA. The latter is cloned in pBluescript and the insert has been sequenced to confirm its authenticity. Subcloning it in pTrc99A, a high-expression vector for Escherichia coli has generated a chimeric plasmid, pTrc-WbCI, which has a reading frame for a recombinant protein (rWbCI), having an additional tripeptide (M-E-F) fused to the N-terminus of WbCI. The expression of rWbCI has been ascertained by immunoblot analysis using rabbit anti-WbCI immune sera and quantitated by ELISA. The optimal conditions for the induction of the protein by IPTG, avoiding complications of protein-body formation, have also been standardized. rWbCI has been purified by a simple and rapid procedure of immunoaffinity chromatography, with an overall yield of 1.3 mg/g wet cell. SDS-PAGE analysis shows the presence of a single protein band, attesting to the homogeneity of the preparation; functionally, it is indistinguishable from WbCI since they inhibit alpha-chymotrypsin in an identical manner.

Animals↗
PubMed1997

Bacterial expression of human vitamin D-binding protein (Gc2) in functional form.

In this report, we report the first expression of human vitamin D-binding protein (hDBP), a serum protein with several functions and a multidomained structure, in Escherichia coli. The recombinant protein (reDBP) was expressed as a fusion partner of glutathione S-transferase in order to facilitate proper folding of the reDBP; E. coli-expressed DBP was found to be fully functional with respect to vitamin D sterol binding, interaction with actin, and cross-reactivity with anti-DBP antibody. Furthermore, both natural DBP and reDBP were affinity-labeled with 25-hydroxyvitamin D3-3-bromo[1-14C]acetate in a similar fashion. Availability of an expression system for hDBP in functional form provides opportunity to develop mutants and truncated DBPs to study multiple ligand-binding properties of this protein in relationship with its structure.

Actins↗
PubMed1997

Rel/NF-kappa B and I kappa B proteins: an overview.

Rel/NF-kappa B proteins constitute a family of structurally-related transcription factors that are regulated by interaction with a family of regulatory proteins, the I kappa B proteins. In this review, we will familiarize the reader with the known Rel/NF-kappa B and I kappa B molecules, and will discuss the types of interactions that occur between these proteins to regulate their function. In addition, we will describe what is known about the structure of Rel/NF-kappa B transcription complexes on DNA. Lastly, we will discuss the wide variety of biological stimuli and conditions which activate NF-kappa B and the genes whose expression are regulated by this family of transcription factors.

Animals↗
PubMed1997

Optimization of a low-cost truly preemptive multitasking PC diagnostic workstation.

The Windows 95/NT operating systems (Microsoft Corp, Redmond, WA) currently provide the only low-cost truly preemptive multitasking environment and as such become an attractive diagnostic workstation platform. The purpose of this project is to test and optimize display station graphical user interface (GUI) actions previously designed on the pseudomultitasking Macintosh (Apple Computer, Cupertino, CA) platform, and image data transmission using time slicing/ dynamic prioritization assignment capabilities of the new Windows platform. A diagnostic workstation in the clinical environment must process two categories of events: user interaction with the GUI through keyboard/mouse input, and transmission of incoming data files. These processes contend for central processing units (CPU) time resulting in GUI "lockout" during image transmission or delay in transmission until GUI "quiet time." WinSockets and the Transmission Control Protocol/Internet Protocal (TCP/IP) communication protocol software (Microsoft) are implemented using dynamic priority timeslicing to ensure that GUI delays at the time of Digital Imaging and Communications in Medicine (DICOM) file transfer do not exceed 1/10 second. Assignment of thread priority does not translate into an absolute fixed percentage of CPU time. Therefore, the relationship between dynamic priority assignment by the processor, and the GUI and communication application threads will be more fully investigated to optimize CPU resource allocation. These issues will be tested using 10 MB/sec Ethernet and 100 MB/sec fast and wide Ethernet transmission. Preliminary results of typical clinical files (10 to 30 MB) over Ethernet show no visually perceptible interruption of the GUI, suggesting that the new Windows PC platform may be a viable diagnostic workstation option.

Algorithms↗
PubMed1997

Viewport: an object-oriented approach to integrate workstation software for tile and stack mode display.

Diagnostic workstation design has migrated towards display presentation in one of two modes: tiled images or stacked images. It is our impression that the workstation setup or configuration in each of these two modes is rather distinct. We sought to establish a commonality to simplify software design, and to enable a single descriptor method to facilitate folder manager development of "hanging" protocols. All current workstation designs use a combination of "off-screen" and "on-screen" memory whether or not they use a dedicated display subsystem, or merely a video board. Most diagnostic workstations also have two or more monitors. Our central concept is that of a "logical" viewport that can be smaller than, the same size as, or larger than a single monitor. Each port "views" an image data sequence loaded into offscreen memory. Each viewport can display one or more images in sequence in a one-on-one or traditionally tiled presentation. Viewports can be assigned to the available monitor "real estate" in any manner that fits. For example, a single sequence computed tomography (CT) study could be displayed across all monitors in a tiled appearance by assigning a single large viewport to the monitors. At the other extreme, a multisequence magnetic resonance (MR) study could be compared with a similar previous study by assigning four viewports to each monitor, single image display per viewport, and assigning four of the sequences of the current study to the left monitor viewports, and four of the earlier study to the right monitor viewports. Ergonomic controls activate scrolling through the off-screen image sequence data. Workstation folder manager hanging protocols could then specify viewports, number of images per viewport, and the automatic assignment of appropriately named sequences of current and previous studies to the viewports on a radiologist-specific basis. Furthermore, software development is simplified by common base objects and methods of the tile and stack modes. Prototype workstation display software and folder manager protocol implementation will be described and demonstrated.

Data Display↗
PubMed1997

Age-related changes in catalytic activity, enzyme mass, mRNA, and subcellular distribution of hepatic neutral cholesterol ester hydrolase in female rats.

Activity and protein mass of hepatic neutral cholesteryl ester hydrolase (CEH) were measured in liver cytosol and washed microsomes of female Sprague-Dawley rats aged 3, 4, 7, 9, 13, and 16 wk. CEH mRNA was also measured. The microsomal component varied with age and contributed a greater fraction of total activity in females than previously reported in males. Nevertheless, the cytosolic component accounted for 62-80% of activity and 77-94% of immunoreactive protein in postmitochondrial fractions. Cytosolic and microsomal CEH specific activities, relative to total protein, decreased 94 and 83%, respectively, from 3 to 4 wk, prior to onset of puberty at 5 wk, and increased 360 and 137%, respectively, from 12 to 16 wk. These results contrast with an earlier study, in which cytosolic CEH activity of males increased with puberty and declined after 12 wk. Although cytosolic CEH was activated by protein kinase A and inhibited by alkaline phosphatase treatment at all ages, protein kinase activation peaked at 4 wk, coinciding with the initial decrease in specific activity. Specific activity in cytosol and microsomes correlated with CEH mass at all ages, suggesting that this CEH accounts for most variation in cellular activity. In contrast, CEH mRNA varied little from 3-16 wk, indicating that transcriptional regulation does not make a major contribution to the variation in CEH activity and mass in females, although it may make an important contribution to male-female differences in CEH expression. Specific activities of cytosolic and microsomal CEH, relative to immunoreactive CEH protein mass, exhibited changes consistent with posttranslational regulation. These results indicate gender-specific multivalent regulation of hepatic CEH by posttranslational mechanisms during development of female rats.

Aging↗