Biomedical subjects

J M Weber

Publications and source records attributed to J M Weber.

At least 91 records · Page 5Linked to original sources

PubMed1994

Increased capacity for circulatory fatty acid transport in a highly aerobic mammal.

Plasma fatty acid (FA) and albumin concentrations, cardiac output, and hematocrit of dogs and goats [dog-to-goat ratio of maximal oxygen consumption (VO2max) = 2.2] were measured to determine rates of circulatory FA delivery during exercise. Our goals were 1) to characterize the mechanism(s) used by the endurance-adapted species (dog) to support higher rates of FA delivery to working muscles than the sedentary species (goat) and 2) to determine whether circulatory transport is scaled with VO2max. Lipid oxidation was 2.5 times higher in dogs than in goats. Dogs had higher cardiac outputs than goats, but this positive effect on their FA delivery was canceled by higher hematocrit. Dogs always had higher plasma FA concentrations than goats. In contrast, albumin was steady and identical in both species, showing that dogs transport FA at higher rates than goats only because they load more FA on their albumin. Average dog-to-goat ratios for FA delivery (1.5-2.0) were lower than would be expected if this rate were scaled with VO2max. In vitro experiments showed that dog albumin is designed for high rates of FA transport because it can bind 50% more FA than goat albumin. All endurance-adapted species may possess such "aerobic albumins" to supply more circulating FA to their working muscles than sedentary species.

Aerobiosis↗

PubMed1994

Locomotory energetics and metabolic fuel reserves of the Virginia opossum.

Marsupials have lower resting metabolic rates than placental mammals, but it is not clear whether particular species can extend this energetic advantage to locomotion. Some active marsupials have a low cost of locomotion, but other more sedentary species, such as the Virginia opossum, appear to run very inefficiently. Steady-state rates of O2 consumption (VO2) and CO2 production (VCO2) were measured at rest and during horizontal treadmill exercise in wild-caught, trained opossums. Average daily VO2 in in undisturbed animals was 7.73 +/- 0.40 ml O2 kg-1 min-1 (5.67 +/- 0.20 ml O2 kg-1 min-1 during light and 9.84 +/- 0.81 ml O2 kg-1 min-1 during dark hours, mean +/- S.E.M., N = 6). Net cost of locomotion ranged between 6.16 and 8.99 J kg-1 s-1 as speed increased and was always higher than for an average mammal of equivalent mass. Net cost of transport decreased as speed increased and was 15-80% higher than for an average mammal. During aerobic locomotion, most of the energy was provided by carbohydrate oxidation, which accounted for 60-95% of VO2 as speed increased. Glycogen and triglyceride reserves were quantified in the major storage depots to estimate potential survival time and travelling distance. Enough metabolic fuel was stored to survive for at least 1 week without eating, and 95% of this energy was in adipose tissue triglycerides. However, maximal travelling distance was less than 2 km because opossum locomotion is mainly supported by carbohydrate reserves, which represented only 4% of the available energy. We conclude that aerobic, ground locomotion of Virginia opossums is associated with two major energetic handicaps because their particularly high cost of transport and the nature of the main oxidative fuel they consume are both incompatible with prolonged locomotion.

Adipose Tissue↗

PubMed1994

Antigenic characterization of an H3N2 swine influenza virus isolated from pigs with proliferative and necrotizing pneumonia in Quebec.

A new strain of swine influenza A virus, designated A/Swine/Saint-Hyacinthe/150/90 has been isolated from pigs with severe proliferative and necrotizing pneumonia in Quebec. The antigenic characterization of the hemagglutinin was performed by hemagglutination inhibition test, immunoblot and indirect immunoprecipitation using polyclonal antisera. Only the last test was able to detect an antigenic relationship between the hemagglutinin of this isolate and an H3 subtype influenza virus. The immunoprecipitation test was a useful alternative for determining the hemagglutinin of influenza A virus subtypes. The neuraminidase inhibition test demonstrated a reactivity between the A/Swine/Saint-Hyacinthe/150/90 and antiserum against a N2 subtype influenza virus. Our results indicate that this new strain isolated for the first time in the porcine population of Canada is related to A/Sw/Hong Kong/76 H3N2 swine influenza virus.

Animals↗

PubMed1994

Alanine kinetics in humans during low-intensity exercise.

There is little doubt that pyruvate contributes to the increased alanine flux in exercise, but the role of protein breakdown is less clear. To quantify the relative contributions of pyruvate and protein breakdown to the increase in alanine flux observed in exercise, we used a primed, constant infusion of 15N-alanine and 1-13C-lactate. The rate of appearance of alanine, the de novo synthesis of alanine, and rate of alanine release from protein breakdown were determined in five healthy subjects at rest and during exercise. The exercise was performed for 120 min on a treadmill at 45% of the subject's VO2max. The total rate of appearance of alanine, calculated with the 15N-alanine tracer, increased significantly during exercise from 4.9 +/- 0.5 to 7.9 +/- 0.9 mumol.kg-1. The amount of alanine derived from pyruvate also significantly increased during exercise (3.2 +/- 0.3 vs 4.5 +/- 0.7), but the proportion of the total decreased from 65% at rest to 57% during exercise (statistically significant, P < 0.05). Consequently, the alanine derived from protein breakdown significantly increased (1.7 +/- 0.5 vs 3.4 +/- 0.8) and was also increased as percent of total alanine flux. Thus, we conclude that during low-intensity exercise, whole body protein catabolism is accelerated.

Adult↗

PubMed1993

Mapping of the mAb73 epitope on Ad2 E1A proteins with random peptide libraries and deletion mutants.

mAb73, a monoclonal antibody against adenoviruses type 2 and 5 E1A, recognises an epitope within the C-terminal part of this protein. To identify the epitope we used random peptide libraries expressed on the surface of filamentous phages (Fd, M13). We found a consensus sequence homologous to the nuclear transport signal KRPRP at the C-terminus of Ad2 and Ad5 E1A. An E1A mutant deleted for these residues failed to be immunoprecipitated by mAb73, confirming that the nuclear transport signal of E1A is the epitope recognised by mAb73.

Adenoviridae↗

PubMed1993

Isolation and properties of adenovirus type 2 proteinase.

We have cloned and expressed the human adenovirus type 2 proteinase gene in Escherichia coli. The expressed proteinase was isolated by a four-step chromatographic procedure. Purity and identity of the recombinant protein was established by two-dimensional gel electrophoresis, N-terminal sequencing, and specific antisera. The pure enzyme did not contain disulfide bridges, and it consisted of one subunit with a pI of 10.2. It did not show any sign of autocleavage. Labeled iodoacetate bound the pure enzyme while labeled diisopropyl fluorophosphate did not. The protease readily cleaved the viral pVII protein, ovalbumin, fibrin, and actin but had no effect on synthetic penta-, octa-, or nonapeptides carrying the consensus sequence for cleavage. The inhibitory profile of the isolated proteinase and the affinity labeling clearly indicate that the human adenovirus type 2 proteinase is a cysteine rather than a serine proteinase as previously believed. The most likely candidate for an active site residue is one of the two conserved cysteines, Cys-104 or Cys-122.

Adenoviruses, Human↗

PubMed1993

High flow coronary fistula closure by percutaneous coil packing.

Few cases of transcatheter coronary fistula closure have been reported. High flow coronary fistulae are usually treated by surgery. This case report presents a 5.4 liters/min flow coronary fistula percutaneously closed by steel coils. This large flow needed the packing of 25 coils, 10-15 cm long, for its total occlusion.

Arteriovenous Fistula↗

PubMed1993

Organization of the avian adenovirus genome and the structure of its endopeptidase.

In the search for the endopeptidase gene, short segments of genomic DNA were sequenced from the avian adenovirus type 1 (CELO) HindIII C and G fragments. On the basis of homology of the translated segments to Ad2 proteins, the genes for hexon, endopeptidase, DNA-binding protein, and 100K protein were mapped in that order between map units 41 and 63. The endopeptidase gene was encoded within a 900 nucleotide segment extending leftward from the EcoRI site at coordinate 50. The predicted Aavl endopeptidase consists of 206 residues of which 66% are similar to the sequence of the human Ad2 enzyme. Alignment of the known endopeptidase sequences identifies a single conserved histidine (H54) and two conserved cysteine residues (C104, C122) as likely candidates for the catalytic site of this thiol proteinase.

Amino Acid Sequence↗

PubMed1993

An enzyme-linked immunosorbent assay for the detection of IgG and IgM antibodies to human herpesvirus type 6.

A lysate of human herpesvirus type 6 (HHV6) infected HSB2 cells was used as antigen for an enzyme-linked immunosorbent assay (ELISA) for the detection of IgG and IgM antibody to HHV6. 78 clinical samples were tested for the presence of HHV6-specific IgM. Nine specimens, all from children under 4.5 years of age, were found to be reactive indicating probable acute infection with HHV6. Sera from 12 healthy adult blood donors and from 88 of 90 adults over the age of 35 with unspecified health conditions tested negative for HHV6 IgM, indicating a minimum specificity estimate of nearly 98% in these patients. Cross-reactivity of antibody to other herpes viruses with the HHV6 ELISA antigen was not detected. Six hundred and ninety-six serum samples from individuals of different age groups were examined for IgG antibody status. In 94% of these samples, IgG antibody was detected. Our data suggests that most Canadians possess antibody to HHV6 by 1 yr of age and that on average, antibody levels remain high through early adulthood but begin to decline with advancing age. The ELISA described is a reliable test for the measurement of IgG and IgM antibodies for both clinical diagnosis and epidemiological studies.

Adolescent↗

PubMed1993

Mismatch between lipid mobilization and oxidation: glycerol kinetics in running African goats.

Glycerol kinetics and total fatty acid (FA) oxidation of trained African pygmy goats were measured by continuous infusion of [2-3H]glycerol and indirect calorimetry during treadmill exercise at 40, 60, and 85% maximal O2 consumption (VO2max). Our main goals were 1) to determine whether rates of FA mobilization and utilization are eventually matched as exercise intensity increases, thereby minimizing reesterification to supply more FA to working muscles, and 2) to test the hypothesis that lipolytic rate is proportional to aerobic capacity by comparing low-aerobic goats with published values from highly aerobic dogs and humans. Mean rate of glycerol release in the circulation (Ra glycerol) was 3.83 +/- 0.11 at rest, 7.69 +/- 0.88 at 40% VO2max, reached a maximum of 15.32 +/- 0.95 at 60% VO2max, and returned to 10.53 +/- 0.76 mumol.kg-1 x min-1 at 85% VO2max. Lipolytic rate did not match total FA oxidation, implying that Ra glycerol cannot be used as an index of FA utilization, even during intense exercise. A large fraction of total FA released by lipolysis was reesterified at 60 and 85% VO2max, showing that FA mobilization does not limit whole animal FA oxidation at these intensities. Comparing goat, dog, and human responses reveals that mammalian lipolytic rate is scaled with aerobic capacity. High- and low-aerobic species exercising at the same %VO2max mobilize FA in exact proportion with their metabolic rate, suggesting that the relative contribution of FA to total energy provision is independent of VO2max.

Animals↗

PubMed1993

Influenza immunization in children with chronic arthritis: a prospective study.

OBJECTIVE: Influenza immunization is recommended for children with chronic conditions and children receiving chronic acetylsalicylic acid therapy. Our study assessed the safety and immunogenicity of this vaccination in children with chronic arthritis. METHODS: The frequency of possible adverse reactions following influenza vaccination, and virus specific HI antibody levels prior to and 4 weeks after vaccination with an inactivated split virus vaccine prepared for the 1991/92 season, were assessed in a prospective open study of children with chronic arthritis. Thirty-four patients were assessed clinically at vaccination and one month later. Local symptoms at the injection site and systemic symptoms were assessed by diary in 26 patients and 13 immunized healthy control children. RESULTS: Tenderness and/or redness at the injection site, and fever occurred equally in patients and controls. Malaise/nausea occurred in 12 patients and 3 controls (p = 0.3), but patients had more symptomatic days than controls (p = 0.01). No child with inactive arthritis developed a swollen joint following immunization. There were no significant differences between the 2 visits for a.m. stiffness, pain (VAS), global assessment, joint count or erythrocyte sedimentation rate (ESR). More patients improved than deteriorated by each measure. Three patients deteriorated by global assessment, 7 patients had an increased joint count. At least 95% of patients developed presumably protective levels of antibodies (HI titers > or = 40) to each virus. Preimmunization titers, seroresponse rates (4 x rise or rise from < 20 to > or = 40) and final titers were the same between patients (whether or not they were taking prednisone or a second line antirheumatic drug) and controls. CONCLUSION: There was no convincing evidence that influenza vaccination is associated with significant adverse reactions or arthritis flares in children with chronic arthritis. Children with chronic arthritis appeared to respond adequately to influenza vaccination.

Adolescent↗

PubMed1993

Flavobacterial sepsis in massively burned pediatric patients.

An experience with wound sepsis due to Flavobacterium meningosepticum in two pediatric burn patients is described. This organism, which is typically found in water and soil, generally has low pathogenicity but may become clinically important in immunocompromised hosts. It is typically resistant to antibiotics prescribed for infections caused by aerobic, gram-negative bacteria. When flavobacteria are suspected as pathogens, initial therapy should begin with ciprofloxacin, trimethoprim-sulfamethoxazole, or clindamycin.

Adolescent↗

PubMed1993

Primary structure of the canine adenovirus PVII protein: functional implications.

The DNA sequence of an open reading frame (ORF) corresponding to the canine adenovirus type 1 (Can 1, Utrecht strain) pro-VII (PVII) protein gene was determined. 560 base pairs were sequenced from the upstream end of the HindIII-A genomic fragment. The sequence gives the 33 C-terminal residues of the penton base protein followed by the 132 residue PVII protein, thus conforming to the same order and location of these genes as in Ad2. The authenticity of this putative PVII-ORF was confirmed by N-terminal sequencing of the cleavage product VII isolated from Can1 virions and also by PCR analysis of Can1 DNA from infected cells and from virions. In addition, the sizes of PVII and VII obtained from translation of the sequence and the proteins observed on the gels were also in agreement. The PVII proteins of Can1 and Ad2 share 57% sequence homology, particularly near the N-terminal third of the molecule, including conservation of the consensus proteinase cleavage site at residue 23. The PVII protein has a predicted MW of 14,626 Da, and an pI of 12.48. Though data bank searches for homology were negative, these viral proteins have significant functional and sequence analogy with histone H3.

Adenoviridae↗

PubMed1993

Improving survival: infection control and burns.

In the past, survival of the thermally injured patient was greatly hindered by invasive infection that originated in the burn wound. Current treatment modalities, including early excision of the burn wound and prompt wound closure, administration of systemic antibiotics and topical antimicrobial agents, and mechanical isolation, have improved survival. However, infection and the sequelae of infection continue to be the leading causes of morbidity and mortality for the thermally injured patient. In addition, the burn patient remains highly susceptible to other infectious processes. A thorough understanding of infection control and burns are essential to the successful treatment of burn injuries.

Anti-Infective Agents↗

PubMed1992

Pathways for oxidative fuel provision to working muscles: ecological consequences of maximal supply limitations.

The study of metabolic fuel provision and its regulation has reached an exciting stage where specific molecular events can be correlated with parameters of the organism's ecology. This paper examines substrate supply pathways from storage sites to locomotory muscle mitochondria and discusses ecological implications of the limits for maximal flux through these pathways. The relative importance of the different oxidative fuels is shown to depend on aerobic capacity. Very aerobic, endurance-adapted animals such as long distance migrants favor the use of lipids and intramuscular fuels over carbohydrates and circulatory fuels. The hypothesis of functional co-adaptation between oxygen and metabolic fuel supply systems allows us to predict that the capacity of several biochemical processes should be scaled with maximal oxygen consumption. Key enzymes, transmembrane transporter proteins, glucose precursor supply and soluble fatty acid transport proteins must all be geared to support higher maximal glucose and fatty acid fluxes in aerobic than in sedentary species.

Aerobiosis↗

PubMed1992

Primary structure of the murine adenovirus type 1 proteinase.

The DNA sequence of an open reading frame (ORF) corresponding to the murine adenovirus type 1 (Mav1) proteinase gene was determined. 1162 base pairs were sequenced from the downstream end of the SmaI-D Mav1 genomic fragment. The sequence defines the 204 amino acid proteinase, which apparently does not possess the usual L3 polyadenylation signal, but instead the sequence AAATAA. This gene is followed by a 147 amino acid C-terminal portion of the DNA-binding protein, encoded by the complementary strand.

Adenoviridae↗

PubMed1992

Factors affecting homologous overexpression of the Saccharomyces cerevisiae lanosterol 14 alpha-demethylase gene.

The Saccharomyces cerevisiae Lanosterol 14 alpha-demethylase (14DM) gene was overexpressed in S. cerevisiae using promoter sequences of the highly expressed S. cerevisiae glyceraldehyde-3-phosphate dehydrogenase (TDH3) gene. To investigate factors affecting 14DM overproduction, the levels of 14DM-specific RNAs, apoprotein, and heme protein, respectively, were determined and the 14DM-specific RNA levels compared with the RNA levels originating from the endogenous TDH gene(s). The quantitative measurements revealed that the 14DM steady-state RNA levels reached were some three- to five-fold below the theoretically expected values. With a view towards further improving expression of the 14DM gene, the spacing between the TDH3 promoter and the AUG was adjusted precisely and to rule out possible toxic effects exerted by the 14DM protein, the TDH3 promoter was placed under galactose regulation by introducing an UASG segment. Furthermore, the effects of the gene copy number on 14DM overproduction were investigated. From the analysis of the improved expression constructs five conclusions could be reached: (1) expression from the native 14DM gene is comparable to the expression driven by the TDH3 promoter-14DM fusion construct on single copy plasmid vectors; (2) expression from the TDH3 promoter-14DM construct on single-copy vectors is nearly as efficient as expression from the corresponding endogenous TDH3 gene; (3) the gene copy number has an effect on the relative expression levels of the TDH3 promoter-14DM constructs; (4) the steady-state amounts of protein produced are very nearly proportional to gene dosage; and (5) protein toxicity does not have a major impact on 14DM production. The maximum yield of 14DM was in the order of 7% of the total yeast protein and the maximum production of functional 14DM heme protein appears to be limited by the availability of heme.

Base Sequence↗

PubMed1992

Nucleotide and deduced amino acid sequence of the canine adenovirus type 1 proteinase.

The DNA sequence of an open reading frame (ORF) corresponding to the canine adenovirus type 1 (Can1) proteinase gene was determined. A total of 1171 base pairs were sequenced from the downstream end of the HindIII-A Can1 genomic fragment, including adjacent regions corresponding to the carboxy-terminal portions of the hexon and the DNA-binding proteins. The predicted Can1 proteinase consists of 206 residues (23,325 D) of which 68% are identical and 83% are similar to the sequence of the human Ad2 proteinase. Alignment with the Ad2 proteinase identified a number of conserved residues that could form part of the catalytic triad of the enzyme.

Adenoviridae↗