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Biomedical subjects

J M Weber

Publications and source records attributed to J M Weber.

At least 73 records · Page 4Linked to original sources
PubMed1995

Effect of exercise on the plasma nonesterified fatty acid composition of dogs and goats: species with different aerobic capacities and diets.

The goals of this study were to determine: (i) whether mammals mobilize particular nonesterified fatty acids (NEFA) preferentially during locomotion, (ii) if differences in aerobic capacity or diet can affect the pattern of NEFA mobilization and (iii) which individual NEFA are most representative of total NEFA concentration changes, to use them as tracers for turnover studies. Individual NEFA were measured in trained dogs and goats (VO2max dog/VO2max goat = 2.2; where VO2max = maximal oxygen consumption) during treadmill exercise at 40 and 60% VO2max. Important interspecies differences in individual NEFA concentrations could be attributed to differences in aerobic capacity. The more aerobic species (dog) had much higher plasma NEFA concentrations for all but one NEFA (18:0), when compared with the low-aerobic species (goat). In addition, exercise caused a large increase in concentration of individual NEFA in the dogs, with the largest increases seen in 18:1 (150% above resting values) and 16:0 (60% increase), but it had no effect in goats. Therefore, the aerobic species has a much higher ability for mobilizing and transporting NEFA in plasma than its low-aerobic counterpart. Two NEFA accounted for more than half total plasma NEFA in both species, 18:1 (about 35% total NEFA) and 16:0 (20%). Calculation of variability in percent composition reveals that oleate and palmitate also closely reflect changes in total NEFA and are therefore the most appropriate tracers for in vivo kinetic studies in exercising mammals.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerobiosis↗
PubMed1995

Adenovirus protease expressed in insect cells cleaves adenovirus proteins, ovalbumin and baculovirus protease in the absence of activating peptide.

The adenovirus type 2 protease (EP) was expressed by infecting insect cells with a recombinant baculovirus. Immunoblot and activity analysis showed EP to be present in both the nucleus and cytoplasm. While the insect cell expressed EP was more soluble than the Escherichia coli expressed EP, its activity was one quarter of the latter, suggesting that eukaryotic postsynthetic modifications are not essential for enzyme activity. EP inactivated a cytoplasmic cathepsin-like baculovirus-encoded cysteine protease which carries a single EP cleavage site and which was capable of digesting most adenovirus structural proteins in vitro. In addition to cleavage of the baculovirus protease, the adenovirus EP was also able to cleave ovalbumin and canine adenovirus protein pre-VII, in the absence of activating peptide. EP activation therefore may occur by means of factors other than the specific activating peptide.

Adenoviruses, Canine↗
PubMed1995

Central venous catheter sepsis with weekly catheter change in paediatric burn patients: an analysis of 221 catheters.

To document the risk of catheter sepsis associated with central venous catheter changes every 7 days in paediatric burn patients, and analysis of data collected prospectively on 234 such catheters was performed. During an 18-month period there were 301 acutely burned children admitted to a regional paediatric burn facility of whom 53, with an average burn size of 42 per cent TBSA, required 234 central venous catheters. A central venous catheter management protocol was followed which included catheter changes every 7 days. If insertion sites were clean and uninflamed, catheters were replaced by guidewire and the original catheter tip was semiquantitatively cultured. Catheters were replaced to a new site if insertion sites appeared inflamed or catheter tips grew 15 or more colony forming units. Overall, 3.2 per cent (10.9 per cent by Centers for Disease Control definition) of central venous catheters were associated with sepsis. When catheters were replaced by guidewire from one to three times, catheter sites were used for a mean of 15.6 days without an increased rate of line sepsis. There was no difference in sepsis rates between catheters placed at a new site or replaced by guidewire. There were no deaths attributed to catheter-related sepsis. We conclude that a protocol allowing for catheter change to a new site, or replacement by guidewire, every 7 days was associated with a low risk of catheter sepsis in paediatric burn patients.

Acute Disease↗
PubMed1995

A chromosome integration system for stable gene transfer into Thermus flavus.

We have developed a chromosomal integration system for gene transfer into the extreme thermophile Thermus flavus. The system relies on integration at the site of leuB (3-isopropylmalate dehydrogenase) which was cloned from T. flavus. The leuB gene was insertionally inactivated in vitro with a thermostable kanamycin-resistance gene and transformed in single-copy into the chromosome of T. flavus on a plasmid vector. Gene replacement strains required leucine for growth, were stably kanamycin-resistant and could grow in the presence of kanamycin at temperatures up to 55 degrees C.

3-Isopropylmalate Dehydrogenase↗
PubMed1995

Permissive hypercapnia as a ventilatory strategy in burned children: effect on barotrauma, pneumonia, and mortality.

OBJECTIVE: To document the incidence of barotrauma, pneumonia, and respiratory death associated with a mechanical ventilation protocol based on permissive hypercapnia in pediatric burn patients. DESIGN: Retrospective review. MATERIALS AND METHODS: Patients were managed using a mechanical ventilation protocol based on permissive hypercapnia, tolerating moderate (pH > 7.20) respiratory acidosis to keep inflating pressures below 40 cm H2O. MAIN RESULTS: Over a 2.5-year interval, 54 burned children (11% of 495 acute admissions) with an average age of 6.5 years (range 5 weeks to 17 years), average burn size of 44% (range 0 to 98%), and median burn size of 46% required mechanical ventilatory support for an average of 12.5 days (range 1 to 56 days). Inhalation injury was diagnosed in 34 (63%) of the children and 72% percent were admitted within 24 hours of injury. Overt barotrauma occurred in 5.6% of the patients, pneumonia in 32%, and respiratory death in 0%. CONCLUSIONS: A conventional ventilation protocol based on permissive hypercapnia is associated with acceptable rates of barotrauma and pneumonia. The low incidence of respiratory death associated with this strategy suggests that it also minimizes ventilator-induced lung injury.

Acidosis, Respiratory↗
PubMed1995

Recent H3N2 swine influenza virus with haemagglutinin and nucleoprotein genes similar to 1975 human strains.

Of the four pandemic strains of human influenza A virus observed this century, the 1977 virus strain was very similar in all genes to a 1950 isolate. Since mammalian influenza A viruses change annually by genetic drift, this reappearance could only be attributed at that time to conservation of the virus in a frozen state. We report here the isolation of swine influenza A viruses with haemagglutinin and nucleoprotein genes which are virtually identical to those of the human virus that circulated in 1975. We have also found serological evidence that this virus is circulating extensively in Quebec swine herds. We propose that human-like H3N2 influenza A strains may remain invariant for long periods in swine, which may serve as a reservoir for human pandemics.

Amino Acid Sequence↗
PubMed1995

Sulfophthalocyanines for photodynamic inactivation of viruses in blood products: effect of structural modifications.

Transmission of infectious disease through blood transfusions is well known. Ultraviolet irradiation, solvents, and detergents provide a means of sterilizing noncellular blood components. However, these harsh methods are not applicable to cellular blood products. Recently, attempts have been made to sterilize biological fluids using photodynamic treatment and phthalocyanine (Pc) dyes have been advanced as photosensitizers for this purpose. We have evaluated a series of water-soluble Pc, chelated with different central metal ions, substituted to different degrees with sulfonato and t-butyl groups, for their effectiveness to reduce virus infectivity in red blood cell suspensions. Vaccinia virus cytopathogenicity was determined by endpoint serial dilutions in the CV-1 cell line. Anti-viral activity increased with the central metal ion in the following: Ga(III) < Al(III) < Zn(II), and varied inversely with the degree of sulfonation. Furthermore, addition of a t-butyl group onto the trisulfonated dyes (PcS3[t-Bu]) resulted in a 5-40-fold increase in anti-viral potency, suggesting that amphiphilicity enhances the photodynamic activity of the dye. Strong anti-viral photosensitizing properties cannot be the sole selection criterion. Of equal importance is the preservation of blood component integrity. Accordingly, the photohemolytic activity of the dyes was evaluated using the rate of hemolysis as a parameter and a toxicity index was defined. Among the most active dyes, the AlPcS3(t-Bu) complex exhibited the most favorable anti-viral properties combined with a low toxicity index. Our results suggest that trisulfophthalocyanines, bearing an additional t-butyl group to enhance amphiphilicity, are particularly promising dyes for photodynamic blood sterilization.

Animals↗
PubMed1995

Molecular cloning of the pyrE gene from the extreme thermophile Thermus flavus.

Mutants of the extreme thermophile Thermus flavus in the pyrimidine biosynthetic pathway (Pyr-) were isolated by resistance to 5-fluoroorotic acid. The pyrE gene, which codes for the orotate phosphoribosyltransferase, was cloned by recombination with one of the isolated Pyr- T. flavus mutant strains. It was subcloned by complementation of an Escherichia coli pyrE mutant strain and was sequenced. The deduced polypeptide sequence extends over 183 amino acids. Several independent Pyr- mutations were mapped within the pyrE locus by recombination with fragments of the cloned gene.

Amino Acid Sequence↗
PubMed1995

Typing and subtyping of influenza viruses in clinical samples by PCR.

Type A and B influenza viruses can cause a wide spectrum of illness, and these viruses are responsible for considerable mortality and morbidity. Rapid typing of isolates is desirable when amantadine treatment or prophylaxis of contacts of type A influenza virus carriers is considered, but the available rapid techniques lack sensitivity and standard diagnostic methods require expansion of virus in tissue culture or embryonated hens' eggs. We developed a series of oligonucleotide primers able to detect, type, and subtype type A influenza viruses in a single reverse transcription-PCR. RNA was isolated from clinical specimens, and cDNA was generated with random primers. PCR was carried out with a mixture of primers specific for influenza viruses of types B, A/H1 and A/H3, and subtyping of the neuraminidase was carried out on the same cDNA template under identical conditions. Amplified products were detected by ethidium bromide staining of amplified products after agarose gel electrophoresis. When it was used to test 98 clinical specimens, this method was comparable to standard culture techniques in the detection, typing, and subtyping of influenza viruses.

Base Sequence↗
PubMed1995

Moving cheaply: energetics of walking in the African elephant.

Large animals have a much better fuel economy than small ones, both when they rest and when they run. At rest, each gram of tissue of the largest land animal, the African elephant, consumes metabolic energy at 1/20 the rate of a mouse; using existing allometric relationships, we calculate that it should be able to carry 1 g of its tissue (or a load) for 1 km at 1/40 the cost for a mouse. These relationships between energetics and size are so consistent that they have been characterized as biological laws. The elephant has massive legs and lumbers along awkwardly, suggesting that it might expend more energy to move about than other animals. We find, however, that its energetic cost of locomotion is predicted remarkably well by the allometric relationships and is the lowest recorded for any living land animal.

Animals↗
PubMed1994

1993-1994 influenza season: Canadian laboratory diagnoses, strain characterization and post-season serosurvey (Ontario).

In Canada as a whole, influenza A/Beijing/32/92-like virus was the dominant infecting strain in the 1993-1994 season with reported laboratory diagnoses peaking in January 1994. Vaccination is again urged for all persons in high-risk groups. Antibody induced by vaccination does not persist well from season to season and the emerging A/Shangdong/9/93 (H3N2)-like variant is related to A/Beijing/32/92(H3N2) but is inhibited less by antibodies to that strain. Conditions are also consistent with possible increased influenza B activity this season.

Adolescent↗
PubMed1994

Identification of active-site residues of the adenovirus endopeptidase.

Multiple sequence alignment of the 12 adenovirus endopeptidases known to date identified a number of conserved residues which might be important for enzyme activity. Eleven mutants were created in the cloned gene by site-directed mutagenesis to identify the active site of this thiol endopeptidase. Analysis of the proteolytic activity in a crude system using viral precursor proteins, as well as in a purified system with activated proteinases using a new chromophoric octapeptide substrate, yielded results consistent with Cys-104 and His-54 being two members of the active site. This result was confirmed by the carboxymethylation of the reactive Cys-104 and its prevention by the active-thiol-specific agent E64. Although Cys-122 and Cys-126 were also reactive cysteines, mutation of these residues did not affect enzyme activity. Replacement of the active-site Cys-104 by serine converted the enzyme into a serine-like proteinase, sensitive to serine proteinase inhibitors. The absence of homology to other proteinases, particularly at the active-site cysteine, coupled with the requirement for activation by a substrate cleavage fragment, indicates that the adenovirus endoproteinase may represent a new subclass of cysteine proteinases.

Adenoviridae↗
PubMed1994

Femoral arterial catheterization in paediatric burn patients.

Despite the obvious drawbacks associated with prolonged arterial cannulation, arterial catheters are frequently required in paediatric burn patients with respiratory failure to facilitate monitoring of oxygenation, ventilation and blood pressure, and to allow for the painless performance of phlebotomy. Burn patients with respiratory failure frequently require prolonged arterial catheterization, often for more than 72 h, and many of their cannulation sites are burned. We report our favourable 3-year experience with 81 femoral arterial catheters in 36 paediatric burn patients. When small diameter pressure monitoring catheters are used, femoral cannulation sites are associated with a low rate of mechanical and infectious complications.

Adolescent↗
PubMed1994

Sequence and structural analysis of murine adenovirus type 1 hexon.

The genomic region encoding the major capsid protein (hexon) of murine adenovirus type 1 (MAV-1) has been isolated and sequenced. The sequence predicts a 908 residue MAV-1 hexon protein and is flanked by a portion of the upstream pVI gene and the downstream endoproteinase gene. The order of these genes and their location in the middle of the genome are the same as those found in other adenoviruses sequenced to date. Multiple sequence alignment with the other five known hexon protein sequences reveals an overall residue identity of 51% and residue conservation of 66%. In comparison with human adenovirus type 2 (Ad2), MAV-1 hexon has major deletions between residues 141 to 170, 270 to 284 and 446 to 455. Since these regions in the Ad2 hexon are partially exposed on the outer surface of the virion, they may represent type-specific antigenic determinants. The MAV-1 hexon sequence has been modelled using the known three-dimensional structure of the Ad2 hexon. The variable regions in which the mutations, deletions and insertions occur are located in the l1 and l2 loops of the molecule that form the protruding hexon towers on the external surface of the virion.

Amino Acid Sequence↗
PubMed1994

Acute encephalopathy and status epilepticus associated with human herpes virus 6 infection.

A previously healthy 22-month-old boy presented in status epilepticus with high fever. He was comatose, with upper respiratory-tract infection. The seizures responded to anticonvulsant therapy. The boy's temperature returned to normal within 24 hours and he recovered slowly from his encephalopathy. On the third hospital day, he exhibited the characteristic rash of reseola infantum. Acute infection with human herpes virus 6 (HHV-6) was established serologically by enzyme immunoassay. HHV-6 DNA was not detected by polymerase chain reaction in CSF or serum at the onset of illness, but was found three months later in the child's saliva. The pathogenesis of the patient's encephalopathy is discussed. It is concluded that HHV-6 infection should be considered in infants and young children with febrile status epilepticus.

Comorbidity↗