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Biomedical subjects

B Baron

Publications and source records attributed to B Baron.

At least 55 records · Page 3Linked to original sources
PubMed1996

Plasma catecholamine and haemodynamic responses to surgical endodontic anaesthetic protocols.

The effects of varying clinically relevant patterns of anaesthetic-vasoconstrictor combinations used for periradicular surgery on plasma concentrations of catecholamines and haemodynamic responses was studied in the canine model. Five mongrel dogs were anaesthetized with sodium pentobarbitol. A femoral cannula was inserted to measure central blood pressure and an ECG was used to monitor heart rate and any associated arrhythmias. Femoral venous blood samples were drawn before initial injection and at 3 and 10 min after injections. Plasma catecholamine concentrations were determined using high pressure liquid chromatography (HPLC). Injection protocols used three time periods, 30, 60 and 90 s, with solutions containing 1:100,000 and 1:50,000 adrenaline. No significant changes in heart rates or presence of arrhythmias were noted over the experimental protocol. Catecholamine levels in pico moles mL-1 were within the normal range at the 3-min sample level. At the 10-min sample time there was a more erratic range of concentrations, with most samples within the normal range. This may have been due to endogenous release of catecholamines in specific animals. The data identified trends in both the haemodynamic parameters and plasma catecholamine levels that can legitimately support the careful use of higher levels of a vasoconstrictor when patient profiles and surgical needs dictate.

Anesthesia, Dental↗
PubMed1996

[Myocardial infarction with normal coronary angiography. Apropos of 9 cases. A retrospective and comparative study].

This retrospective study was designed to determine the characteristics of myocardial infarction with normal coronary arteries. The files of consecutive patients admitted to hospital for a first infarction in 1992 and 1993 were analysed. Patients younger than 70 years of age, who had undergone coronary angiography during their admission to hospital were selected. A total of 109 infarctions complied with these criteria and 9 of them were associated with angiographically normal coronary arteries. In this series, patients with angiographically normal coronaries tended to be younger than those with at least one stenotic coronary artery (47 +/- 13 years vs 55 +/- 11 years, p = 0.07). The sex ratio did not differ between the two groups. The body mass index of patients with normal coronary arteries was significantly lower (22.9 +/- 3.9 kg/m2 vs 26.3 +/- 3 kg/m2; p = 0.02). These patients more frequently reported a history of phlebitis (3/9 kg/cm2 vs 26.3 +/- 3 kg/cm2; p = 0.02). These patients more frequently reported a history of phlebitis (3/9 vs 2/100). The frequency of anterior and posterior infarctions was virtually the same. Myocardial infarction with normal coronary arteries appears to be less severe, as reflected by the creatine phosphokinase peak (867 +/- 268 IU/l vs 1921 +/- 1389 IU/l), the maximal sum of ST elevation (5 mm vs 16 +/- 12 mm; p = 0.05), the percentage of left ventricular akinesia on angiography (25.5 +/- 4 vs 38.7 +/- 11.8; p = 0.01), and the lower ventricular end-diastolic pressure (11.5 +/- 3.5 mmHg vs 38.7 +/- 11.8 mmHg; p = 0.02). Fewer complications were observed during the acute phase, with no deaths. During the subsequent follow-up, with a median of 2 years, no recurrent infarctions, no cardiac decompensation and no deaths were observed in the group with normal coronary arteries. Two patients presented an episode of angina and one developed a recurrent episode of phlebitis. In the other group of 100 patients, 12 deaths were observed during the acute period, followed subsequently by 2 other deaths, 10 episodes of recurrent angina, 2 recurrent infarctions and 12% of patients developed heart failure. In this series, infarction with normal coronary arteries therefore appears to have a good prognosis, possibly because of more limited myocardial necrosis. No abnormalities of haemostasis or coagulation were observed in these patients.

Adult↗
PubMed1995

Molecular characterization of an 18 kb segment of DNA puff C4 of Bradysia hygida (Diptera, sciaridae).

The data presented here are an extension of the molecular characterization of DNA puff C4 of Bradysia hygida. A cDNA related to a gene amplified in this puff and expressed when puff C4 expands was cloned and sequenced. Analysis of the amino acid sequence deduced from the open reading frame present in the cDNA indicate that the encoded protein is secreted and comprises mostly alpha-helical coiled-coil. An 18 kb genomic segment containing the transcription unit of this gene was also cloned and the structure and expression of the 1.4 kb mRNA was determined. Quantitative slot blot hybridization of DNA complementary to the transcription unit shows that this gene is amplified about 21 times in the salivary gland, confirming data previously obtained. Fragments upstream of the 5' end, and beyond the 3' end, of the gene transcription unit were also analysed and shown to be amplified at least eight and five times, respectively. Based on these data we discuss how amplification could occur at DNA puffs.

Amino Acid Sequence↗
PubMed1994

The highly conserved Chinese hamster GNAI3 gene maps less than 60 kb from the AMPD2 gene and lacks the intronic U6 snRNA present in its human counterpart.

The identity of a gene coamplified with the adenylate deaminase 2 gene (AMPD2) in coformycin-resistant cells was determined by analysis of its genomic sequence. Sequence comparisons reveal a significant homology with the 3' terminal part of the gene encoding the alpha i3 subunit of Gi proteins from several species (GNAI3). Identification of the gene was confirmed by Western blot analysis of its products. A precise sequence comparison was performed with the human genomic sequence. It showed that conservation remains important in noncoding exons as well as in introns. However, sequences corresponding to combined U6 snRNA and E protein pseudogene, previously identified inside intron 7 of the human gene, were not found in the Chinese hamster gene. GNAI3 is mapped to a region of conserved linkage between human chromosome 1 (locus 1p13) and mouse chromosome 3 (at 48.4 cM). The Chinese hamster GNAI3 gene maps to chromosome 1 within a 120-kb fragment that also comprises the AMPD2 and GSTM genes.

AMP Deaminase↗
PubMed1993

New Ki-67-equivalent murine monoclonal antibodies (MIB 1-3) generated against bacterially expressed parts of the Ki-67 cDNA containing three 62 base pair repetitive elements encoding for the Ki-67 epitope.

BACKGROUND: The monoclonal antibody Ki-67 reacts with a human nuclear cell proliferation-associated antigen that is expressed in all cells that are not in G0. Recently, we could demonstrate that Ki-67 detects a double band in Western blots of proliferating cells with apparent molecular weights of 345 kilodaltons and 395 kilodaltons, respectively. Furthermore, initial molecular biologic data favored the view that the epitope detected by Ki-67 might be encoded by a repetitive 66 bp element. EXPERIMENTAL DESIGN: In order to verify this assumption, parts of the Ki-67 cDNA were bacterially expressed, and the fusion proteins obtained were used to elicit new monoclonal antibodies. The specificities of the new reagents were tested by immunohistochemistry, Western blot, and enzyme-linked immunosorbent assay techniques. RESULTS: The somatic cell fusions revealed a number of antibodies with immunoreactivities comparable to Ki-67. Three antibodies, designated MIB 1-3, were further characterized. Besides the fact that their immunostaining reactivity is identical with that of Ki-67, all new antibodies react in Western blots with native Ki-67 antigen. Furthermore, Western blot and competitive binding assays by enzyme-linked immunosorbent assay clearly demonstrate that MIB 1 and MIB 3, like the original Ki-67 antibody, react with an epitope that is encoded by the 66 bp repetitive element mentioned above. MIB 2, however, reacts with an epitope distinct from this latter structure. In addition, after antigen unmasking by microwave treatment, MIB 1 and MIB 3 detect the Ki-67 antigen in paraffin sections. CONCLUSIONS: Our results demonstrate that it is possible to use bacterially expressed parts of the Ki-67 antigen as immunogen to elicit antibodies that react with the native antigen. While MIB 1 and MIB 3 detect the same or a very similar epitope as the original antibody Ki-67, MIB 2 clearly differs in its fine specificity. Our results provide a circle of evidence that the cDNA sequence thus far determined encodes for the Ki-67 antigen. Furthermore, the new antibodies may become powerful tools for routine histopathology and for further functional characterization of the Ki-67 antigen.

Amino Acid Sequence↗
PubMed1992

Elution mode of Pneumocystis carinii cysts in gravitational field-flow fractionation.

The simplest field-flow fractionation technique, i.e. gravitational, was used in an attempt to purify a Pneumocystis carinii cyst suspension. This parasite is an opportunistic invader in immunocompromised patients, especially those suffering from AIDS. The cyst stage is spherical and 5 microns in diameter. Unexpected retention times, not systematically related to the size and the density of the parasite, were obtained under various experimental conditions. When silicone-coated walls were used, Pneumocystis carinii cysts were eluted in the void volume, whereas when uncoated walls were used with a sodium dodecyl sulphate-enriched carrier phase, retention was observed. These phenomena are probably related to the high degree of hydrophobicity of these micrometre-sized biological particles; this degree can be easily determined. The use of the gravitational field-flow fractionation technique can be of a great interest for the development of new methods for diagnostic purposes. Particle-wall interactions and their modifications due to the carrier phase or to the wall treatment can be employed in the search for new bronchoalveolar lavage solutions.

Animals↗
PubMed1992

A new strategy useful for rapid identification of microsatellites from DNA libraries with large size inserts.

Microsatellites are new powerful polymorphic markers used for gene mapping. Their characterization requires that all the sequence surrounding the repeat be known in order to be able to design primers for PCR amplification. However, when using DNA libraries with large cloned inserts, this sequence characterization is not immediately practicable. In this paper, we describe a new strategy, based both on the use of a microsatellite specific probing and on the creation of nested deleted clones with the Exonuclease III, in order to position microsatellites in a range allowing direct sequencing. This method was applied to the screening of a mouse chromosome 19 DNA specific library. In this way, thirteen clones were identified by specific probing and seven were submitted to the nested deletion strategy. Five of them presented microsatellite sequences in specific deleted subclones which were selected and sequenced. Primers were designed for each of them and polymorphism between the genomes of several inbred strain of mouse have been determined. These microsatellites were mapped, three of them to chromosome 19 and two to chromosome 11.

Animals↗
PubMed1992

[P wave changes and atrial fibrillation after implantation of VVI type pacemaker].

The P waves of patients with VVI pacemakers were compared with those of DDD pacemakers at implantation and then regularly for 5 years. A certain number of cardiac pathologies are known to cause P wave changes. The incidence of atrial fibrillation (AF) was much higher in VVI than in DDD patients. In the VVI group, the incidence was much greater in patients paced for sinus node disease than in patients paced for AVB. Analysis of sinus P wave characteristics in 320 patients with VVI pacemakers shows progressive abnormalities of atrial function with time. The expression of this atrial dysfunction is a statistically significant prolongation of the P wave in V1 and dII and of the terminal part of the P wave in V1. The factors responsible for this abnormality and which favours the occurrence of AF are quasi-permanent pacing, the presence of retrograde conduction and an abnormality of atrial activation at the time of implantation.

Aged↗
PubMed1991

Indicators of clinically significant red cell antibodies produced by sensitized lymphocytes in liver transplant patients.

It has been documented that transplanted livers can carry sensitized lymphocytes that subsequently produce red cell antibodies. We evaluated immunohematological variables in liver donors and recipients for indicators that might be predictive of serological red blood cell (RBC) destruction mediated by the passenger lymphocytes. Organ donor sera with antibody scores greater than ( > ) 60 correlated with a positive direct antiglobulin test (DAT) and need for increased RBC transfusion in liver transplant recipients. We therefore propose an antibody screen on all potential liver donors and titration of unexpected alloantibodies; titration of ABO antibodies of liver donors who demonstrate minor ABO-incompatibilities with their recipients; and, when needed, transfusion of group O RBCs to recipients of livers from donors with minor ABO-incompatibility who have antibody scores >60.

Journal Article↗
PubMed1990

Construction and characterization of a DNA library from mouse chromosomes 19 purified by flow cytometry.

In spite of the constant development concerning physical mapping of eukaryotic genomes, the mouse chromosome 19 remains poorly characterized. In order to improve the possibilities for studying this chromosome, we have constructed a chromosome-specific EcoRI DNA fragment library from mouse chromosomes 19 sorted by flow cytometry. The resulting library contains about 3 X 10(4) recombinant clones. The identified inserts range in size from about 0.2-10 kb, with a 4 kb average size and with no observable redundancy. The purity of the library has been analyzed by flow-blot. For that purpose, chromosomes from 2 cell lines, 1 with a normal karyotype and 1 with translocated chromosome 19, were sorted on nylon filters and hybridized with 9 clones of the library. Results show that 5 clones out of the 9 clearly originate from sorted chromosomes 19 and 3 and are likely to be derived from its DNA, thus indicating that the library of chromosome 19 is of high purity.

Animals↗
PubMed1990

[Influence of preload changes on the filling function of the left heart ventricle studied by Doppler echocardiography].

Left ventricular filling may be studied non-invasively by Doppler echocardiographic recording of transmitral blood flow. This study reports the variations in this flow induced by changing cardiac preload by administering trinitrin or by vascular filling in 27 patients undergoing catheterisation. Left ventricular end diastolic pressure (LVEDP) was measured by the pig-tail catheter used for ventriculography. Transmitral flow was recorded by pulsed Doppler using the apical view. The parameters studied were those of the early diastolic E wave and the end diastolic A wave. The hemodynamic and echocardiographic measurements were performed under basal conditions, after trinitrin and after vascular filling. Trinitrin was given to 14 patients and led to a fall in LVEDP from 17.6 +/- 4.5 to 6.7 +/- 1.4 mmHg (p less than 0.001). The amplitude of the mitral E wave decreased and the E/A ratio fell from 0.93 +/- 0.37 to 0.71 +/- 0.32 (p less than 0.001). Thirteen patients underwent vascular filling which increased LVEDP from 10.9 +/- 5 to 27 +/- 4 mmHg (p less than 0.001). The mitral E wave increased and the E/A ratio rose from 0.96 +/- 0.32 to 1.27 +/- 0.23 (p less than 0.01). The patients received trinitrin and then underwent vascular filling. The LVEDP decreased from 16 +/- 3.9 to 8 +/- 2.9 mmHg (p less than 0.001) and then rose to 28.3 +/- 3.5 mmHg (p less than 0.001). The E/A ratio fell after trinitrin from 0.91 +/- 0.40 to 0.58 +/- 0.30 (p less than 0.01) and then rose to 1.42 +/- 0.60 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Aortic percutaneous transluminal valvuloplasty in elderly patients by balloon larger than aortic anulus.

Twenty-four elderly patients (79 +/- 7 years) with long-standing calcified aortic stenosis have been divided in two comparable groups of 12. The first group was treated with 19 mm balloon percutaneous transluminal valvuloplasty, where the balloon diameter was always smaller than the aortic anulus diameter. Peak-to-peak aortic valve gradient decreased from 76 +/- 32 mmHg to 30 +/- 19 (P less than .05), and the aortic valve area, calculated by Gorlin formula, increased from 0.40 +/- 0.17 cm2 to 0.57 +/- 0.17 (P less than .05). The second group was treated with a trefoil 25 mm balloon, always larger than the aortic anulus diameter. In this second group, peak-to-peak aortic valve gradient decreased from 73 +/- 34 mmHg to 23 +/- 15 (P less than .05), and aortic valve area increased from 0.47 +/- 0.14 cm2 to 0.88 +/- 0.36 (P less than .05), increasing thus more than in group I (P less than .05). Clinical tolerance to balloon inflation was not the same according to individual patients but was similar between the two groups; complications were comparable in the two groups. These results suggest that aortic valvuloplasty by trefoil balloon larger than aortic anulus can provide wider aortic valve area without increasing complication rate.

Aged↗
PubMed1988

[Bepridil and bundle of His block. Apropos of a case].

The first case of atrioventricular block located in His bundle observed during oral treatment with bepridil is reported; the block subsided when the drug was discontinued and reappeared when it was reintroduced. Electrophysiological studies performed with bepridil have shown that, as could be foreseen from its beneficial or undesirable effects, this calcium antagonist has some properties of Vaughan Williams' class I antiarrhythmic agents and alters subnodal conduction. Clinical studies indicate that in therapeutic doses this alteration has little or no significance, but it may reach clinical expression when latent of patient pre-existing disorders of conduction within or below His bundle are present.

Bepridil↗