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Biomedical subjects

P Roy

Publications and source records attributed to P Roy.

At least 307 records · Page 17Linked to original sources
PubMed1989

Synthesis and binding affinities of cyclic and related linear analogues of CCK8 selective for central receptors.

To investigate the role of the sulfate group and the influence of cyclization on the biological properties of conformationally constrained CCK8 analogues, three series of compounds were synthesized: Boc-Glu-Tyr-Nle-D-Lys-Trp-Nle-Asp-Phe-NH2 (1), Boc-Glu-Tyr(SO3H)-Nle-D-Lys-Trp-Nle-Asp-Phe-NH2 (2), and Boc-Glu-Tyr-(SO3H)-Nle-D-Lys-Trp-Nle-Asp-Phe-NH2 (3) (series A); Boc-D-Glu-Tyr-Nle-D-Lys-Trp-Nle-Asp-Phe-NH2 (4), Boc-D-Glu-Tyr(SO3H)-Nle-D-Lys-Trp-Nle-Asp-Phe-NH2 (5), Boc-D-Glu-Tyr(SO3H)-Nle-D-Lys-Trp-Nle-Asp-Phe-NH2 (6), and Boc-D-Glu-Tyr(SO3H)-Nle-D-Nle-Trp-Asp-Phe-NH2 (7) (series B); and Boc-gamma-D-Glu-Tyr-Nle-D-Lys-Trp-Nle-Asp-Phe-NH2 (8), Boc-gamma-D-Glu-Tyr(SO3H)-Nle-D-Lys-Trp-Nle-Asp-Phe-NH2 (9), and Boc-gamma-D-Glu-Tyr-(SO3H)-Nle-D-Lys-Trp-Nle-Asp-Phe-NH2 (10) (series C). The selectivity of these peptides was studied by measuring their ability to displace [3H]propionyl-CCK8 from guinea pig brain and pancreatic membranes. All the peptides displayed low affinities (KI values around 10(-6) M) for the pancreatic receptors (A type). In contrast, both sulfated and nonsulfated cyclic analogues displayed high affinities for central-type binding sites (B type), especially compounds belonging to series C [KI(8) = 4.7 nM and KI(9) = 0.56 nM]. In all series the linear analogues had relatively poor affinities (KI approximately 300 nM) for B-type receptors. Compound 9 was the most potent (KI = 0.56 nM) and selective [KI(pancreas)/KI(brain) = 4464] for central-type CCK receptors of guinea pig. The cyclization of the N-terminal region of CCK8 permits one therefore to obtain probes for central receptors, and small changes directed toward the cyclic part modulate the affinity for these receptors.

Amino Acid Sequence↗
PubMed1989

Completion of the sequence of bluetongue virus serotype 10 by the characterization of a structural protein, VP6, and a non-structural protein, NS2.

The sequence of cDNA clones representing the entire genome of bluetongue virus serotype 10 (BTV-10) has been completed by the analysis of data obtained for the S8 and S9 segments. Each DNA clone has been sequenced completely and the deduced amino acid sequences have been analysed. The sequences of the S8 and S9 gene products as well as another two previously published small gene products (S7 and S10) have been compared with the corresponding size gene products of reovirus type 1. The data do not indicate a relationship between the small proteins of these two viruses except some distant homologies between the BTV VP7 protein and the sigma 1 protein of reovirus. The characteristics of all the BTV-10 genome segments, the deduced primary gene products and their possible functions are summarized.

Amino Acid Sequence↗
PubMed1989

Expression of two related nonstructural proteins of bluetongue virus (BTV) type 10 in insect cells by a recombinant baculovirus: production of polyclonal ascitic fluid and characterization of the gene product in BTV-infected BHK cells.

In vitro translation of bluetongue virus (BTV) double-stranded RNA in the rabbit reticulocyte lysate system has shown segment 10 (S10) to code for two related proteins, NS3 and NS3A. The presence of both products in vivo, however, has remained unconfirmed owing to the very low level of synthesis of the S10 gene product(s) in BTV-infected BHK cells. In the present work, a cDNA copy of BTV type 10 (BTV-10) S10 RNA was inserted into Autographa californica nuclear polyhedrosis baculovirus (AcNPV) in lieu of the 5' coding region of the AcNPV polyhedrin gene. Spodoptera frugiperda cells infected with the recombinant baculovirus synthesized two polypeptides, which were shown to represent NS3 and NS3A by Western blot (immunoblot) and peptide map analysis. Antibodies raised to the expressed NS3 by immunization of mice detected both NS3 and NS3A in BTV-10-infected BHK cells but not in purified BTV-10 virus particles. In contrast to in vitro translation of BTV S10 RNA in which NS3 and NS3A are synthesized in equimolar amounts, NS3 was the principle product both in the baculovirus expression system and in vivo in BTV-infected cells. The results indicate the caution which should be exercised when using the rabbit reticulocyte lysate system to predict the pattern of protein synthesis from a gene with alternative start codons. The expressed NS3 and NS3A proteins reacted strongly with sera from sheep infected with homologous and heterologous BTV serotypes, suggesting that the S10 gene products are highly conserved group-specific antigens.

Amino Acid Sequence↗
PubMed1989

Expanded polytetrafluoroethylene prostheses as secondary blood access sites for hemodialysis: pathological findings in 29 excised grafts.

The popularity of expanded polytetrafluoroethylene (PTFE) arteriovenous fistulas for hemodialysis access is increasing. The low infection rate, low thrombogenicity and low body reactivity make it an important blood access for patients on routine hemodialysis. The authors examined 29 PTFE graft fistulas surgically excised from patients on hemodialysis for one or more of the following complications: infection 7, 2 with associated hemorrhage; thrombosis 9; aneurysm 11, 3 with associated thrombosis; stenosis 5, 3 with associated thrombosis; hemorrhage 4 and arterial steal 2. The explanted prostheses were reinforced Gore-tex in 20, Gore-tex thin wall in 1, Impra I in 4, Impra II in 3 and Vitagraft in 1. It was also noted that the implants failed in the short term mainly because of infection, in the medium term mainly because of thrombosis and stenosis, and in the long term usually because of aneurysm.

Adult↗
PubMed1989

Biologic and structural evaluation of 80 surgically excised human umbilical vein grafts.

Human umbilical vein is a valuable alternative to autogenous saphenous vein in lower-limb revascularization. However, the long-term patency is not as good. To understand better the reasons for this, the authors studied the biologic and structural changes occurring in 80 segments of human umbilical vein (HUV) grafts excised from 70 patients. Morphologic, histologic and scanning electron microscopy examinations were performed on each specimen. It was noted that increasing duration of implantation was associated with greater encapsulation and less surrounding inflammatory reaction. Twenty-six percent of clinically noninfected grafts were found to harbour bacteria. Bacteremic colonization was often in the folds of the luminal surface. As a result of these findings, the authors emphasize the need for complete excision of clinically infected grafts. Anastomoses between HUV segments are discouraged because they are associated with a high frequency of infection and a corresponding decrease in duration of implantation. Delamination of the wall was common, and such sites may represent areas at risk for further degradation. Continued surveillance of the biologic and structural changes occurring in excised grafts remains an important method in increasing our understanding of the evolutive complications of HUV grafts.

Adult↗
PubMed1989

Phentolamine for enhanced visualization of distal arteries in lower extremity arteriography.

To augment visualization of the distal arteries, phentolamine was administered to 83 patients (164 limbs) undergoing lower extremity arteriography. Arterial visualization was graded into three classes and skin temperatures were recorded. Phentolamine provided very good visualization of the distal arterial bed in 95% of limbs. A strong correlation was observed between the temperature rise of the feet and the class of arterial visualization. No side effects were recorded. The use of phentolamine in lower extremity arteriography is recommended.

Angiography↗
PubMed1988

Evidence for genetic relationship between RNA and DNA viruses from the sequence homology of a putative polymerase gene of bluetongue virus with that of vaccinia virus: conservation of RNA polymerase genes from diverse species.

The nucleotide sequence of segment 1 of the double stranded RNA genome of bluetongue virus serotype 10 (BTV-10), encoding the largest viral core protein, VP1, has been determined. Linear sequence analysis of the predicted amino acid sequence of the 149-K Da protein, a putative component of the viral RNA-directed RNA polymerase, revealed extensive homology with the vaccinia virus 147K Da DNA-directed RNA polymerase subunit. Similar homologies were detected between the VP1 polypeptide and the beta chain subunit of Escherichia coli and common tobacco chloroplast RNA polymerases, yeast RNA polymerase II and III and fruit fly polymerase II.

Amino Acid Sequence↗
PubMed1988

Isolation, characterization and sequencing of a novel repetitive DNA from the mung bean Vigna radiata.

A family of highly reiterated, small (approx. 300 bp) sequences has been identified in DNA of the mung bean Vigna radiata. The members are extensively interspersed throughout the chromosomes with some clustering. They also occur extrachromosomally. There is no tissue-specificity to the repeat family but it is highly species-specific. The repetitive DNA hybridizes to total RNA as well as to polyadenylated RNA isolated from germinated mung beans. It has analogy with the human AluI family in the mode of isolation, size, genomic distribution, copy number and transcribability though they do not share any sequence homology. A repetitive DNA clone was selected from a shotgun genomic library of mung bean DNA in pBR322. The average copy number of the cloned repeat is estimated to be 8 x 10(4) per haploid genome, and thus constitutes approx. 5% of the total mung bean genome. The genomic organization and transcription of the cloned repeat is reported. Sequencing of the cloned repetitive DNA reveals the presence of the number of direct and inverted repeats and some short palindromic sequences.

Base Sequence↗
PubMed1988

Multiple forms of atrial natriuretic factor receptor in human placenta.

Multiple forms of atrial natriuretic factor receptor have been identified in human placental membranes. Atrial natriuretic factor binds specifically to placental membranes and the binding activity could be solubilized using non ionic detergent, Triton X-100. Binding to the detergent solubilized preparation was inhibited 80% by the addition of 0.5 M sodium chloride. Affinity cross-linking analysis indicated that this binding was associated with a single protein band of molecular weight 170-kDa. On the other hand, if sodium chloride was added together with a chelator, o-phenanthroline, ANF binding to this preparation was stimulated 300%. Binding under these conditions was not to the 170-kDa protein but was associated with a broad band in the region of 100/110-kDa and a minor band at 200-kDa. These observations clearly indicated that in human placental membranes, atrial natriuretic factor binds to distinctly different molecular species depending on the presence or absence of certain ions and chelators. The two types of binding could be conveniently assayed in the presence of each other by elimination or inclusion of sodium chloride and o-phenanthroline in the assay system.

Atrial Natriuretic Factor↗
PubMed1988

Clinical experience with the Monorail balloon catheter for coronary angioplasty.

The Monorail balloon catheter is distinctly different from other current balloon catheters: the guidewire passes through the balloon itself, exits the catheter proximal to the balloon, and runs alongside its small shaft (3 French) through the guiding catheter. Monorail coronary angioplasty was attempted in 61 patients on 73 lesions with balloons from 2.0 to 3.7 mm. Angiographic success was obtained in 66 lesions (90%). For 15 lesions, balloon exchanges were needed. In three lesions, the Monorail balloon failed to cross the lesion, while a standard balloon succeeded; two lesions could not be crossed with any balloon. Vessel occlusion occurred in four patients: two had emergency surgery without infarct (one died suddenly 4 days later and one had a stroke 1 day later), one was recanalized with a standard balloon, and one had a myocardial infarct. Continuous infusion of urokinase was used until patient 3 in whom problems with the delivery system led to cardiocerebral air embolization (with complete recovery). No thrombotic complications were observed in the subsequent 58 patients with only a bolus of 10,000 U of heparin. The Monorail balloon facilitates contrast injections and balloon exchanges but appears more difficult to pass through tight lesions. Omission of the previously recommended infusion with a thrombolytic agent proved safe.

Adult↗
PubMed1988

Silent ischemia: a relevant problem in patients with coronary artery disease?

Awareness of silent myocardial ischemia has greatly increased during the last few years in the medical community. Methods for its detection include exercise testing, Holter monitoring, and, more specifically, Thallium-201 scintigraphy, 2D-echocardiography, and multigated radionuclide ventriculography with phase analysis, all during rest and exercise. Cohn's classification of silent ischemia has proven very useful in highlighting the magnitude of the problem. It can be estimated that about 2% to 4% of apparently healthy middle aged males in industrialized European countries are prone to asymptomatic ischemic episodes. Prognosis of silent myocardial ischemia has been evaluated in prospective and retrospective studies. Most authors come to the conclusion that ischemia is the key finding, whether painful of asymptomatic. Even present understanding of pain perception from the ischemic myocardium is incomplete; the high prevalence and the relation with myocardial infarction and sudden cardiac death make silent myocardial ischemia one of today's most relevant problems.

Coronary Disease↗
PubMed1988

Genetic relationships of bluetongue virus serotypes isolated from different parts of the world.

Full-length DNA clones representing the 10 double-stranded RNA segments of US bluetongue virus serotype 10 (BTV-10) have been used in a study to determine the genetic relationships among 20 different BTV serotypes. The study was undertaken using Northern blot hybridization techniques involving 32P-labelled DNA probes and total RNA species extracted from BHK-21 cells infected with 20 different BTV serotypes. The results obtained indicate that all the genes representing the nonstructural proteins of BTV (NS1, NS2 and NS3) as well as most of the inner capsid polypeptides are highly conserved (e.g., VP1, VP3, VP4), while VP6 and VP7, the remaining two inner capsid components, are less conserved. The genes representing the two outer capsid polypeptides, VP2 and VP5, vary significantly. When complete DNA clones of RNA segment 2 (representing the VP2 neutralization gene) of 4 other US serotypes (BTV-2, -11, -13 and -17) and one Australian serotype (BTV-1) were used in similar hybridization studies, the data obtained showed that despite geographical distances, a certain BTV serotype exhibits similarities. Some hybridization signals were detected with several of the inner capsid genes and the corresponding RNA segments of epizootic hemorrhagic disease virus (EHDV), a distantly related orbivirus, although none of the BTV outer capsid genes, nor any of the nonstructural genes hybridized with either EHDV-1 or EHDV-2 RNA species.

Animals↗