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Biomedical subjects

B Martin

Publications and source records attributed to B Martin.

At least 253 records · Page 14Linked to original sources
PubMed1992

Infectious and mechanical complications of central venous catheters placed by percutaneous venipuncture and over guidewires.

OBJECTIVE: To compare the frequency of infectious and mechanical complications of central venous and pulmonary artery catheters placed by initial venipuncture vs. over a guidewire at existing sites. HYPOTHESIS: Exchange of central venous catheters and pulmonary artery catheters over a guidewire as opposed to fresh venipuncture reduces mechanical complications without increasing risk of infection. DESIGN: Chart audit. PATIENTS: Medical, surgical, and coronary ICU patients requiring invasive monitoring or central venous access. INTERVENTIONS: Patients requiring prolonged catheterization underwent periodic exchange of catheters over a guidewire. Rates of catheter-related infections and mechanical complications were determined for central venous catheters placed by initial venipuncture and those catheters placed by guidewire exchange. MEASUREMENTS AND MAIN RESULTS: Over a 12-month period, 939 catheters were inserted in 454 patients. Of these 939 catheters, 534 were placed by guidewire exchange. Use of a guidewire was associated with a decreased frequency of pneumothorax and hemothorax compared with initial venipuncture (0/405 [0%] vs. 7/534 [1.3%], respectively; p < .05) but not with increased risk of infection (9/405 [2.2%] vs. 14/534 [2.6%], respectively; NS). Guidewire-facilitated replacement of multiple consecutive catheters at the same site did not increase the risk of catheter-related infection. Catheters placed via internal jugular veins were more likely to become infected than catheters placed via subclavian veins (17/477 [3.6%] vs. 3/430 [0.7%], respectively; p < .01). CONCLUSIONS: When prolonged central venous or pulmonary artery catheterization is necessary, periodic catheter replacement over a guidewire is associated with fewer mechanical complications than initial venipuncture. Periodic catheter replacement over a guidewire is also associated with no increase in risk of infection.

Bias↗
PubMed1992

Effects of Water-Deficit Stress on Photosynthesis, Its Components and Component Limitations, and on Water Use Efficiency in Wheat (Triticum aestivum L.).

It is of theoretical as well as practical interest to identify the components of the photosynthetic machinery that govern variability in photosynthesis rate (A) and water-use efficiency (WUE), and to define the extent by which the component processes limit A and WUE during developing water-deficit stress. For that purpose, leaf exchange of CO(2) and H(2)O was determined in two growth-chamber-grown wheat cultivars (Triticum aestivum L. cv TAM W-101 and cv Sturdy), and the capacity of A was determined and broken down into carboxylation efficiency (c.e.), light- and CO(2)-saturated A, and stomatal conductance (g(s)) components. The limitations on A measured at ambient CO(2) concentration (A(350)) were estimated. No cultivar difference was observed when A(350) was plotted versus leaf water potential (Psi(w)). Light- and CO(2)-saturated A, c.e., and g(s) decreased with decreasing leaf Psi(w), but of the corresponding photosynthesis limitations only those caused by insufficient c.e. and g(s) increased. Thus, reduced stomatal aperture and Calvin cycle activity, but not electron transport/photophosphorylation, appeared to be major reasons for drought stress-induced inhibition of A(350). WUE measured as A(350)/g(s) first increased with stomatal closure down to a g(s) of about 0.25 mol H(2)O m(-2) s(-1) (Psi(w) = -1.6 MPa). However, it was predicted that A(350)/g(s) would decrease with more severe stress due to inhibition of c.e.

Journal Article↗
PubMed1992

Lung function testing in adults with preferential nasal breathing.

Three adult patients with asthma with preferential nasal breathing were found to have a typical pattern of lung function test results with substantial between test variation. This condition can be identified as a cause of unsatisfactory performance in respiratory tests by observing the patient's reaction after the nostrils have been occluded.

Aged↗
PubMed1992

Selective synthetic ligands for human nuclear retinoic acid receptors.

From a series of naphthalene and benzoic acid derivatives we have identified synthetic retinoic acid analogues exhibiting high selectivity for the nuclear retinoic acid receptors RAR alpha (Am 580), RAR beta (CD 2019) and RAR gamma (CD 437) as well as ligands sharing high affinities for all RAR subtypes (CD 367). The compounds were evaluated in two complementary screening systems: (1) binding to nuclear proteins extracted from COS-7 cells after transfection with the appropriate expression vectors, and (2) induction of plasminogen activator in the embryonic mouse teratocarcinoma cell line F9. All compounds behaved as retinoic acid agonists in the F9 test.

Binding, Competitive↗
PubMed1992

Unbalanced karyotype due to adjacent 1 segregation of t(11;22)(q23.3;q13.2).

The 11q;22q translocations, whatever the breakpoints may be, are of particular interest because of their propensity to 3:1 segregation of the chromosomes at meiosis I. Until now, no unbalanced karyotype resulting from 2:2 adjacent segregation was published among offspring of 11q;22q translocation carriers. The authors report the case of an unbalanced karyotype due to adjacent 1 segregation of a maternal translocation (11;22)(q23.3;q13.2). The proband's karyotype was 46,XX,-22,+der(22)(11;22)(q23.3;q13.2)mat. This finding demonstrates that adjacent 1 segregation is possible in t(11;22) with breakpoints at 11q23 and 22q13, and can lead to birth of viable infants.

Abnormalities, Multiple↗
PubMed1992

The effect of intra- and intermolecular disulfide bonds after peptide grafting on the properties of yeast alcohol dehydrogenase.

Hydrophilic peptides including cysteine residues were grafted on activated yeast alcohol dehydrogenase. The grafted enzyme preparation was then submitted to oxidation at various concentrations in order to favour the formation of intramolecular or intermolecular disulfide bonds. Intermolecular bonds led to enzyme inactivation. But a rigidification of the enzyme was observed with intramolecular bonds. However, thiol groups also chelated the catalytic and structural zinc atoms, leading to the corresponding enzyme inactivation and thermolability. Formation of intramolecular disulfide bridges after peptide grafting strengthens enzyme conformation and can induce enzyme stabilization, but it has to take into account the possible interference with the naturally occurring cysteine bridges.

Alcohol Dehydrogenase↗
PubMed1991

Comparisons between patterns of convulsions induced by two beta-carbolines in 10 inbred strains of mice.

The beta-carbolines, methyl-beta-carboline-3-carboxylate (beta-CCM) and 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM) are known to have pharmacological properties opposite to those of agonistic benzodiazepines. Convulsions induced by these drugs lead to differential patterns, such as clonus, myoclonic or tonic seizures. In 10 different inbred strains of mice we investigated whether the responsiveness to the two drugs was the same, irrespective of the pattern of convulsions. We found the same ranking in the responsiveness of the strains to both drugs in the case of myoclonic seizures. No such correlation could be found for clonus or tonic seizures. Our conclusion is that the same genetic factors determine myoclonic seizures, whereas a plurality of mechanisms underly the other patterns. Thus, myoclonic seizures seem to be the most appropriate index for evaluating the convulsant action of beta-carbolines in genetic experiments.

Animals↗
PubMed1991

Genetic difference in sensitivity to beta-carboline: evidence for the involvement of brain benzodiazepine receptors.

The convulsive effects of methyl beta-carboline-3-carboxylate (beta-CCM), a benzodiazepine receptor ligand, are different in two inbred strains of mice: BALB/cBy mice are more sensitive to beta-CCM than C57BL/6J mice. In the present article, we report the effects of [3H]flunitrazepam binding in these two strains, which suggest a possible explanation of the differences in their sensitivity to beta-CCM by the involvement of brain benzodiazepine receptors.

Animals↗
PubMed1991

Purification and properties of sialoadhesin, a sialic acid-binding receptor of murine tissue macrophages.

Macrophage subpopulations in the mouse express a lectin-like receptor, sialoadhesin (originally named sheep erythrocyte receptor, SER), which selectively recognizes sialoglycoconjugates and is likely to be involved in cellular interactions of stromal macrophages in haematopoietic and lymphoid tissues. In this report we describe the purification and ligand specificity of sialoadhesin isolated from mouse spleen. Purified sialoadhesin, a glycoprotein of 185 kd apparent Mr, agglutinated sheep or human erythrocytes at nanomolar concentrations in a sialic acid-dependent manner. Low angle shadowing and electron microscopy showed that sialoadhesin consisted of a globular head region of approximately 9 nm and an extended tail of approximately 35 nm. To investigate the specificity for sialic acid, we studied the interaction of sialoadhesin with derivatized human erythrocytes, glycoproteins, and glycolipids. In conclusion, sialoadhesin specifically recognizes the oligosaccharide sequence Neu5Ac alpha 2----3Gal beta 1----3GalNAc in either sialoglycoproteins or gangliosides. These findings imply that specific sialoglycoconjugates carrying this structure may be involved in cellular interactions between stromal macrophages and subpopulations of haematopoietic cells and lymphocytes.

Animals↗
PubMed1991

Symptom schemata in chronic respiratory patients.

In view of evidence that illness prognoses and adaptive functioning may be influenced by the accuracy of people's knowledge about their physical symptoms, the present study extended these findings to the chronic care population. It was hypothesized that individuals hold beliefs and develop theories about their physical symptoms and that the accuracy of these beliefs is predictive of the individuals' general level of adaptive functioning. A modified version of an instrument designed to measure the accuracy of illness schemata was employed with a sample of 31 chronic respiratory patients. Accuracy rating correlated positively and significantly with ratings of adaptive functioning, whereas no relationship was observed between adaptive functioning and severity of the patients' medical condition. Well-informed patients functioned at a higher level physically, psychologically, and socially than less-informed patients. These findings point to the importance of patient education for prognosis. Possible mediating factors are discussed.

Adult↗
PubMed1991

The Epstein-Barr virus carrier state: dominance of a single growth-transforming isolate in the blood and in the oropharynx of healthy virus carriers.

Epstein-Barr virus (EBV) isolates can be broadly classified as type 1 or type 2 on the basis of allelic polymorphism of the virus-encoded nuclear antigens EBNAs 2, 3a, 3b and 3c, and individually identified based on Mr values of their EBNA proteins (EBNA type). Here we have used this natural heterogeneity amongst isolates to re-examine the question of EBV persistence in vivo, asking in particular whether virus carriage in oropharyngeal epithelium and/or in B lymphoid tissues involves infection with a single or with multiple virus strains. Firstly, 76 healthy virus carriers were classified into serotype groups on the basis of preferential antibody reactivity to type 1 EBNAs (serotype 1) or to type 2 EBNAs (serotype 2); 60 of the 76 donors were serotype 1, four of the 76 donors were serotype 2 and 12 of the 76 donors were anti-EBNA 2, 3a, 3b, 3c antibody-negative and therefore could not be serotyped. Representative donors from each group were then selected for virus isolations from blood (by spontaneous in vitro transformation) and from throat washings (by cord blood cell transformation). All 13 serotype 1 donors tested and six of seven non-serotypeable donors gave a type 1 virus isolate, whereas all four serotype 2 donors and one of the seven non-serotypeable donors gave a type 2 isolate. Multiple transforming virus isolates from any one donor, whether from blood or throat washings, were all of the one strain characteristic of that particular donor; sequential isolations showed retention of the same strain over several years. Finally, throat washing samples from these same donors were examined for amplifiable EBV DNA in the polymerase chain reaction using EBV type-specific oligonucleotide primers and probes derived from the polymorphic EBNA 2 and EBNA 3c loci. The results were consistent with earlier virus isolation studies, each individual donor showing amplification either of type 1 or type 2 sequences. We conclude that multiple EBV infections must occur rarely, if at all, in healthy virus carriers; EBV persistence in vivo is characterized by dominance of a single transforming virus strain.

Adult↗
PubMed1991

Mismatch repair genes of Streptococcus pneumoniae: HexA confers a mutator phenotype in Escherichia coli by negative complementation.

DNA repair systems able to correct base pair mismatches within newly replicated DNA or within heteroduplex molecules produced during recombination are widespread among living organisms. Evidence that such generalized mismatch repair systems evolved from a common ancestor is particularly strong for two of them, the Hex system of the gram-positive Streptococcus pneumoniae and the Mut system of the gram-negative Escherichia coli and Salmonella typhimurium. The homology existing between HexA and MutS and between HexB and MutL prompted us to investigate the effect of expressing hex genes in E. coli. Complementation of mutS or mutL mutations, which confer a mutator phenotype, was assayed by introducing on a multicopy plasmid the hexA and hexB genes, under the control of an inducible promoter, either individually or together in E. coli strains. No decrease in mutation rate was conferred by either hexA or hexB gene expression. However, a negative complementation effect was observed in wild-type E. coli cells: expression of hexA resulted in a typical Mut- mutator phenotype. hexB gene expression did not increase the mutation rate either individually or in conjunction with hexA. Since expression of hexA did not affect the mutation rate in mutS mutant cells and the hexA-induced mutator effect was recA independent, it is concluded that this effect results from inhibition of the Mut system. We suggest that HexA, like its homolog MutS, binds to mismatches resulting from replication errors, but in doing so it protects them from repair by the Mut system. In agreement with this hypothesis, an increase in mutS gene copy number abolished the hexA-induced mutator phenotype. HexA protein could prevent repair either by being unable to interact with Mut proteins or by producing nonfunctional repair complexes.

DNA Repair↗
PubMed1991

Selective high affinity retinoic acid receptor alpha or beta-gamma ligands.

Biological effects of retinoic acid (RA) are mediated through its binding to three closely related nuclear receptors (RAR alpha, RAR beta, and RAR gamma) belonging to the steroid-thyroid nuclear receptor family. RARs are able to modulate the transcription of specific genes by binding to responsive elements located in the promoter-enhancer region of these genes. As demonstrated by in situ hybridization, the distribution of each RAR type in the developing embryo, as well as in the adult, is not uniform. In this context, synthetic retinoids that would behave as selective ligands would be invaluable for studying the respective roles of each RAR type in cultured cells, whole animals, and embryos. Moreover, from a pharmacological point of view, such selective compounds may possess a higher therapeutic index and a lower teratogenic risk, because they might affect specific tissues and spare some others. As an approach to this problem, we have set up two complementary assays, (i) an in vitro binding assay to determine the Kd values of retinoids for RAR alpha, RAR beta, and RAR gamma and (ii) a functional assay in cultured cells to evaluate the potential of retinoids to transactivate, through their binding to one type of RAR, a reporter gene. The binding assay uses nuclear extracts of COS-7 cells transfected with vectors expressing RAR alpha, RAR beta, or RAR gamma. The functional assay is a measure of chloramphenicol acetyltransferase (CAT) activity in HeLa cells co-transfected with the expression vectors used in the binding assay and the reporter gene TRE-tk-CAT. Selective agonists for RAR alpha (Am80 and Am580) and RAR beta-RAR gamma (CD495 and CD564) were identified. However, compounds with pure RAR beta or RAR gamma selectivity have not yet been identified.

Carrier Proteins↗
PubMed1991

SOFI: a bidimensional detector for fast direct on-line quantification of beta particles on blots.

We present a high-speed, high-resolution beta imager developed to replace autoradiographic films currently used in molecular biology experiments. It allows the user to locate and make quantitative analyses of 32P-labeled molecules on a 25.6 x 25.6-cm flat surface. Combining new techniques--scintillating optical fibers and multianode photomultipliers--this fast imager offers several advantages when compared with recent gas detectors and flexibility for further improvements. Several biological applications will be discussed.

Animals↗
PubMed1991

[Single-compartment arthroplasty of the knee using the Marmor-Cartier method. Apropos of a series of 100 cases].

100 unicompartmental knee prosthesis type Marmor-Cartier with 86 replacements of the medial compartment have been followed for a period of 5 to 15 years. Contrary to the reaxation osteotomies, a moderate hypocorrection about 3 to 5 degrees has to be respected in unicompartmental knee replacement. The two major complications are degradation of the contralateral compartment due to hypercorrection; and loosening of the tibial plateau due to hypocorrection over 5 degrees or anterior laxity or convex side laxity or misalignment of the prosthetic device. The unicompartmental knee arthroplasty is a trustful surgical procedure as long as precise indications for this method and a rigorous surgical technique are respected.

Adult↗
PubMed1991

The fate of cancellous and cortical bone after transplantation of fresh and frozen tissue-antigen-matched and mismatched osteochondral allografts in dogs.

After implantation, a massive osteochondral allograft cannot be completely protected from the stresses that are produced by weight-bearing, and it is susceptible to collapse during incorporation, revascularization, and substitution. How these processes are affected by disparities between the tissue antigens of the host and the graft remain unclear. To clarify the role of histocompatibility antigen-matching in the incorporation of cancellous and cortical bone, we orthotopically implanted both fresh and cryopreserved dog leukocyte-antigen-matched and mismatched proximal osteochondral radial allografts in beagles. Four groups of beagle dogs were used; they received (1) a dog leukocyte-antigen-mismatched frozen allograft, (2) a dog leukocyte-antigen-mismatched fresh allograft, (3) a dog leukocyte-antigen-matched fresh allograft, or (4) a dog leukocyte-antigen-matched frozen allograft. In twelve dogs, a sham operation was done in the contralateral limb (the first living donor had a sham operation), and in the remaining ten dogs, the proximal part of the contralateral radius was removed and then replaced as an autogenous (control) graft. The animals were given fluorochromes periodically, and they were killed eleven months after the operation. The osseous portion of the grafts was evaluated radiographically, biomechanically, and histomorphometrically. No dog had grossly obvious clinical abnormalities, all host-graft interfaces healed, and no joints dislocated. Radiographic examination of the allografts frequently showed deformation of the radial head and variable peripheral resorption. No significant difference in the modulus of elasticity at the host-graft interface was found among the groups. The repair process of the cortical bone was similar for all grafted segments. New periosteal and endosteal bone formed, and the cortical bone became porotic as vessels penetrated it. The uptake of fluorochrome was the most active in the autogenous grafts and the least active in the fresh antigen-mismatched grafts. The volume of cancellous bone was significantly greater and the trabeculae were thicker in all allografts compared with the bones on which a sham operation had been done and compared with the autogenous grafts. The volume of intertrabecular fibrous connective tissue was directly proportional to the immunogenicity of the allografts, and the percentage of the surface on which bone was forming tended to be inversely proportional to the immunogenicity of the allografts. The grafts were revascularized by the ingrowth of vessels into the intertrabecular spaces; necrotic trabeculae were not penetrated by vessels. This pattern was particularly pronounced in the antigen-mismatched grafts, regardless of whether they were fresh or frozen.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗