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Biomedical subjects

B Gay

Publications and source records attributed to B Gay.

At least 55 records · Page 3Linked to original sources
PubMed1994

Phenotypic characterization of insertion mutants of the human immunodeficiency virus type 1 Gag precursor expressed in recombinant baculovirus-infected cells.

A panel of 28 insertion mutants of the human immunodeficiency virus type 1 (HIV-1) Gag precursor (Pr55Gag) was constructed by linker-insertion mutagenesis and expressed in recombinant baculovirus-infected insect cells. One set of 14 mutants carried the normal N-myristylation signal; the other set constituted their non-N-myristylated counterparts. The mutants were characterized with respect to (i) assembly and extracellular release of membrane-enveloped budding Gag particles, (ii) intracellular assembly and nuclear transport of Gag cores, (iii) specific processing of Pr55Gag by HIV-1 protease in vivo, and (iv) binding of Pr55Gag to an HIV-1 genomic RNA probe in Northwestern blotting. Insertions within the region between amino acid residues 209 and 334 in the CA domain appeared to be the most detrimental to Gag particle assembly and release of Gag into the external medium, whereas a narrower window, between residues 209 and 241, was found to be critical for secretion of soluble Pr55Gag. Differences in Pr55Gag processing in vivo and RNA binding in vitro between N-myristylated and non-N-myristylated Gag mutants suggested a major conformational role for the myristylated N terminus of Gag precursor. In coinfection experiments using wild-type Gag- and mutant Gag-expressing recombinants, a transdominant negative effect on Gag particle assembly and release was observed for insertions located in two separate domains, the matrix and nucleocapsid.

Amino Acid Sequence↗
PubMed1993

Comparative pharmacokinetics of free muramyl tripeptide phosphatidyl ethanolamine (MTP-PE) and liposomal MTP-PE.

The comparative pharmacokinetics of free MTP-PE (muramyl tripeptide phosphatidyl ethanolamine) and MTP-PE entrapped in negatively charged multilamellar liposomes (liposomal MPT-PE) was evaluated in rats at a bolus intravenous (i.v.) dose of 0.2 mg/kg and in dogs at a bolus i.v. dose of 0.1 mg/kg. Additional studies were performed with the free form in rats (1.4 mg/kg, bolus i.v.) and dogs (1 mg/kg, bolus i.v.) and with the liposomal form in dogs (0.5 mg/kg, bolus i.v.). Plasma samples were obtained at various times up to 48 h postinjection and assayed for the drug by a chemiluminescence immunoassay. The pharmacokinetic data regarding liposomal MTP-PE describe the distribution of free drug released from liposomes and total drug concentrations. The present studies demonstrate that the distribution characteristics of MTP-PE changed dramatically depending on the dosage form. The elimination kinetics of free MTP-PE from blood is substantially slower than that of the liposomal drug. For liposomal MTP-PE, free drug levels in plasma are very low compared with free MTP-PE. In rats at a dose of 0.2 mg/kg, 96% of MTP-PE contained in liposomes is removed from the plasma compartment 10 min after injection, and in dogs at a dose of 0.1 mg/kg, 100% of MTP-PE contained in liposomes is removed in the same time period. This rapid phase of liposome clearance is followed by a slower rate of clearance for the remainder of the liposomes in rats at a dose of 0.2 mg/kg and in dogs at a dose of 0.5 mg/kg.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1993

[Experience with the endoprosthesis in comminuted fractures of the humeral head].

Surgical treatment is difficult in elderly patients who have suffered a comminuted fracture of the head of the humerus, often associated with dislocation. We performed follow-up examinations in our hospital in 11 patients after implantation of 12 endoprostheses since July 1990. Very good results were confirmed in respect of regained freedom of movement and overall high personal satisfaction on the part of the patients. Endoprosthesis appears to us as the treatment of choice in complex fractures of the head of the humerus in patients of advanced age.

Aged↗
PubMed1992

Purification and biochemical characterization of non-myristoylated recombinant pp60c-src kinase.

To obtain sufficient material for the biochemical and biophysical study of pp60c-src, we have utilized a recombinant pp60c-src baculovirus lacking the myristoylation site at codon 2. On infection of Sf9 cells, this virus produced large amounts of soluble non-myristoylated pp60c-src. The use of non-myristoylated pp60c-src (1) increases production of pp60c-src compared with the wild-type protein, (2) facilitates purification, (3) yields a stable product and (4) allows biochemical studies in the absence of detergents. Up to 20 mg of pp60c-src of greater than 95% purity has been purified from 6 litres of Sf9 cells grown in a bioreactor. One major and multiple minor forms of pp60c-src were separated by Mono Q f.p.l.c. Isoelectric focusing of purified pp60c-src species revealed heterogeneity, some of which could be attributed to differences in the tyrosine phosphorylation state of the enzyme. Kinetic analysis of non-myristoylated pp60c-src kinase in the presence of Mg2+ gave Km values for angiotensin II and ATP of 2 mM and 30 microM respectively and a Vmax. of 620 nmol/min per mg. The kinetic constants and metal ion preferences of a number of copolymers and peptide substrates have been compared. Polylysine and poly(GLAT), which was not phosphorylated by the pp60c-src kinase, dramatically activated autophosphorylation of Tyr-416, suggesting a conformation modulation of pp60c-src by charged polymers. This finding implies that Tyr-527 dephosphorylation is not sufficient for full activation of pp60c-src in vitro.

Amino Acid Sequence↗
PubMed1992

Computed tomography in traumatology with special regard to the advances of three-dimensional display.

There is a variety of methods to aid in the diagnosis of fractures requiring operative treatment. A computer program that produces pseudo-three-dimensional (3D) images from sets of axial computed tomograms is used for examining fractures in areas of complex skeletal anatomy. The resulting reconstructions, representing the surface in a form similar to that of anatomic preparations, can facilitate the process of diagnosis. They are also valuable for planning operations. The 3D information can be used to define the size, shape, and location of the various fracture types. We have used the technique in more than 500 patients with injuries to the skull, spine, acetabulum, sternoclavicular joint, shoulder, knee, and calcaneus and are able to demonstrate the benefit of special investigation protocols.

Calcaneus↗
PubMed1992

Autoprocessing of the human immunodeficiency virus type 1 protease precursor expressed in Escherichia coli from a synthetic gene.

A gene encoding an N-terminally extended precursor of 107 residues of the human immunodeficiency virus type 1 protease (PR107) was chemically synthesized and cloned into a bacterial expression vector, under the control of the araB promoter. PR107 was expressed alone or fused in phase to the amino or carboxy terminus of the bacterial beta-galactosidase (beta-gal). The yield of protease and beta-gal was found to be significantly higher when the gene for PR107 was cloned upstream of the Escherichia coli lacZ gene (PR107-beta-gal). Comparisons of the level of cloned protein expression between protease precursor and mature form suggested that this enhanced expression was due to the additional 5' sequence of the PR107 gene, and occurred at the post-transcriptional level. Autoprocessing of protease precursor and its release from the beta-gal fusion protein were analysed using wild-type and mutated cleavage sites. Mutations were introduced at amino acids downstream of the F-P scissile bond, at positions P4' and P5' in the C-terminal site (TLNF*PISP), and at position P3' in a consensus N-terminal site (TLNF*PQITL) placed at the protease-beta-gal junction. The data obtained suggested that (i) autoprocessing at the carboxy-terminal F-P bond was not significantly influenced by the presence of the N-terminal precursor sequence, (ii) P4' and P5' substitutions in the C-terminal site had no effect on cleavage, and (iii) P3' in the N-terminal site tolerated a wide variety of substitutions.

Amino Acid Sequence↗
PubMed1992

Expression and extracellular release of human immunodeficiency virus type 1 Gag precursors by recombinant baculovirus-infected cells.

The level of synthesis and extracellular release of human immunodeficiency virus type 1 Gag by insect cells was analyzed, using eight different recombinants of Autographa californica nuclear polyhedrosis virus harboring various constructs of the gag gene, cloned under the polyhedrin promoter. The results obtained suggested that gag expression was mainly regulated at the transcriptional level and was not significantly influenced by posttranslational events, e.g., Gag self-assembly, nuclear transport, or extracellular release. Two different forms of Gag were found in the culture medium of recombinant-infected cells. One form consisted of membrane-enveloped, corelike particles released by budding at the plasma membrane; the other of nonparticulate, soluble Gag polyprotein molecules. Both forms coexisted in recombinants expressing Gag with an intact N-terminal myristylation signal, whereas recombinants expressing nonmyristylated Gag released solely the soluble form. This suggested that myristylation of the N terminus was not a prerequisite for efficient extracellular release of Gag by insect cells, which could proceed via two independent but simultaneous mechanisms.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[The value of Ender nailing in hip para-articular femoral fractures in gerontologic traumatology. Ender nailing--hip para-articular femoral fractures--gerontologic traumatology].

Nailing according to Ender is one of several competing methods of osteosynthesis for treating per- and subtrochanteric fractures of the femur in geronto-traumatology. Within 5 years we have treated 62 geriatric patients by this procedure. The average-age of our patients was about 76 years. Only 20 of them were able to be examined after a time of ca. 37 months post operationem. Intraoperative complications were backing out of the femur corticalis at the entry hole, followed by perforations of the head or neck of the femur. In one case we saw a supracondylar fracture. In the postoperative period we mostly found dislocations of the nails to cranial or caudal. Moreover there were one wound infect and one pseudarthrosis. The mortality rate came to 6.5% and was never caused by the method. When leaving the hospital the majority of the elderly patients was mobilized and able to walk. In spite of reduction of function of hip and knee and external rotation deformity and shortened legs the patients declared to be content with the result of the operation. Important geronto-traumatological aspects of the Endernailing-method could be seen in the simple procedure, the short operating time, a minimal surgical trauma and a diminishing of the risk of the mostly multi-morbid patients. Regarding the great number of specific complications competing methods are going on to be preferred. Meanwhile the application of Endernails is an exception in geronto-traumatology.

Aged↗
PubMed1991

Functional domains of HIV-1 gag-polyprotein expressed in baculovirus-infected cells.

Seven recombinants of AcNPV harboring various forms of complete or truncated gag gene from HIV-1 were constructed to determine which functional domains of the gag polyprotein are implicated in its self-assembly and cellular localization. The p6 carboxy-terminal portion of the p15 NCgag domain appeared to be dispensable for assembly, budding, and release of gag particles by insect cells. However, all the morphopoietic information was not entirely confined to the p9 NC domain, as N-myristylation could compensate for p15 NC deletion in gag assembly and the budding process. The two consensus karyophilic signals situated in the p17 MAgag domain were inefficient for targeting nonmyristylated forms of gag polyprotein to the nucleus when the p6 NC domain was deleted. In the presence of p6, or with a third, baculovirus-specific, karyophilic signal added at its N-terminus, gag particles relocated in the nucleus. These data suggested that p6 played a critical role in the conformation of gag polyprotein.

Amino Acid Sequence↗
PubMed1990

Detection of rubella virus in amniotic fluid by electron microscopy.

We report in this paper the observation of rubella virus by electron microscopy in an amniotic fluid sample, collected from a pregnant woman with rubella infection. Virological investigations by inoculation of cell cultures with amniotic fluid and fetal blood remained negative, due probably to the presence of neutralizing antibodies in the samples. Electron microscopy is a rapid but weakly sensitive method to detect viruses in clinical specimens. However, this unusual observation would indicate that in some cases electron microscopy could be a useful technique to evidence a fetal rubella infection.

Adult↗
PubMed1990

[Problems and incidence of abdominoperineal impalement injuries].

In our population of trauma patients abdomino-perineal impalement injuries are very rare. With reference to our own patients we demonstrate the problems that arise with impalement injuries: infection, hemorrhage, intraabdominal organ lesions and difficulty in recognizing these. The necessity for elicitation of a precise history and meticulous diagnostic examination is undisputed. In our own patients we have always tried to achieve definitive therapy as a primary procedure. There have been no lethal complications.

Abdominal Injuries↗
PubMed1988

[Computed tomography in the diagnosis of injuries of the posterior pelvic girdle].

Sixty-two patients who had suffered trauma to the posterior part of the pelvis were examined by CT and conventional methods; the latter showed abnormalities in only 70%. This part of the body is involved particularly frequently in the case of high velocity injuries. An obvious fracture of the ventral part of the pelvis, with or without ligamentous injury, is an indication for performing CT in order to clarify the situation and to evaluate the stability of the pelvis.

Fractures, Bone↗
PubMed1987

Carbohydrate metabolism of dog skeletal muscle during immobilization.

The effect of immobilization and the following mobilization on muscle carbohydrate metabolism was investigated in dogs. Total carbohydrate and glycogen content of skeletal muscle fell during immobilization. The glycogen-degrading enzyme phosphorylase was activated 1 week after immobilization (a/b ratio 40.6 +/- 7.6 vs. 27.1 +/- 6.5%). Thereafter, the enzyme activity decreased and remained significantly lowered even 2 weeks after the following mobilization. In contrast, muscle glucose and lactate concentration were unchanged. Our data indicates glycogen breakdown of dog skeletal muscle during immobilization. Even after 2 weeks of mobilization muscle glycogen content has not reached glycogen values of the untreated dogs.

Animals↗
PubMed1987

[Computerized tomography diagnosis of acetabulum fractures].

One hundred and ten acetabular fractures in 102 patients were examined by CT. In 78% there was agreement with the findings on conventional radiological examination. CT altered the classification of fractures, particularly if these were complex. CT was superior to conventional radiology for demonstrating the course of the fractures and for identifying local complicating factors. In 68 surgical explorations, specificity of CT was found to be 97%. After the age of 40 there was a tendency for complex fractures. Analysis of the fractures in three dimensions often determines the need for surgical treatment, particularly if the weight-bearing portion of the acetabular roof and the posterior bony column has been fractured.

Acetabulum↗