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)

Predicted structure of the adenovirus DNA binding protein

The DNA sequence of a portion of the MAV1 SmaI-D fragment coding for the C-terminal 147 amino acids of the adenoviral DNA-binding protein (DBP) has been determined. A multiple sequence alignment was constructed of the MAV1 fragment and the DBPs of Ad.2, 4, 5, 7, 12, 40, and 41 to examine the degree of conservation of features that have been mapped on the Ad.2 DBP and to identify further conserved features. The less conserved N-terminal segment of the protein contains two nuclear localization signals and two acidic regions, the host range region, and all of the 11 phosphorylation sites. The highly conserved C-terminal segment contains a potential leucine zipper and zinc finger motifs. These sequence features were mapped onto a predicted secondary structure of the Ad.2 DBP.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Reduction of c-myc expression correlated with E1a expression but not with the transformed phenotype

The adenovirus E1a oncogene has both positive and negative regulatory effects on the expression of a variety of host genes. Both type of effects have been reported for certain cell cycle genes such as c-myc. To study the potential role of c-myc in adenovirus transformation, we have assessed the steady-state levels of c-myc mRNA after serum stimulation in genetically related transformed or non-transformed cell lines in the presence or absence of E1a. Serum stimulated the accumulation of stable c-myc mRNA only in cell lines which did not express E1a. Therefore under the present assay conditions, E1a had a negative effect on the steady-state level of c-myc mRNA. Surprisingly, this effect was independent of the transformed phenotype.

Adenovirus transformation revertant resistant to retransformation by E1 but not by SV40-T and HPV16-E7 oncogenes

We have previously described a revertant cell line which expresses a dominant tumor suppressor phenotype to E1 but not to heterologous oncogenes such as c-myc, N-ras, or polyoma middle t (Sircar et al. (1988) Oncogene 3, 725-728). DNA tumor virus oncogenes have been suggested to transform cells via the common mechanism of sequestering the Rb-105 antioncoprotein. This paradigm would predict that our revertant cell line, which is resistant to retransformation by E1a, should also be resistant to the other members of the Rb-105 binding family of oncogenes. To test this hypothesis we transfected the revertant cell line with plasmids bearing SV40-T or the HPV16-E7 oncogenes. Because transformation was obtained by both oncogenes at efficiencies similar to the transformation of a related revertant cell line, the results suggest that the resistance phenotype is specific to E1a. This specificity was further confirmed by cell fusion experiments.

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.

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.

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.

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.

Complementation of adenovirus early region 1a and 2a mutants by Epstein-Barr virus immortalized lymphoblastoid cell lines

Human B-lymphocytes may be infected by both adenoviruses and the Epstein-Barr virus (EBV). Some of the immediate early and early proteins in the two viruses are similar in function even though their primary structures are different. As these viruses might infect the same B-cells in man, we asked if complementation could take place. The adenovirus mutant H5ts125 has a thermolabile DNA-binding protein and is defective in DNA replication at 39 degrees. Several EBV-transformed human lymphoblastoid cell lines and a tamarin cell line B95-8 were infected with H5ts125 and incubated at either the nonpermissive or the permissive temperatures. Adenoviral DNA replication and assembly of new virions were observed at both temperatures, suggesting complementation by the resident EBV gene products. The adenovirus E1a region is deleted in the mutant d1312. Complementation of this mutant was only obtained in the EBV producer B95-8 cells. Immortalization by EBV was apparently not sufficient for effective complementation. This supports an earlier observation that one of the EBV early proteins (MS-EA) behaves like adenovirus E1a and can transactivate the E4 promoter in a CAT assay. The complementation of mutant adenoviruses in EBV-transformed lymphocytes may help the rescue of new adenovirus serotypes in immunosuppressed patients.

Effect of endurance swimming on the lactate kinetics of rainbow trout

The lactate turnover rate of rainbow trout (Oncorhynchus mykiss) was measured by bolus injection of [U-14C]lactate at rest and during prolonged swimming at 85% Ucrit to determine the importance of this metabolic fuel for endurance locomotion in fish, to assess whether lactate exchange between white and red muscle could be a possible mechanism for supplying oxidizable fuel to their lateral red muscle, and to compare the contribution of lactate to total energy provision between teleost and mammalian species. Turnover rate only increased from 4.41 +/− 0.33 to 9.71 +/− 1.69 mumol kg-1 min-1 between rest and prolonged swimming, and the contribution of lactate oxidation to total metabolism declined during exercise. Lactate exchange between white and red muscle is, therefore, not a significant mechanism to fuel the active lateral red musculature during prolonged swimming. The lactate turnover rate of teleosts is one or two orders of magnitude lower than in mammals of equivalent size, but lactate has the same importance as a fuel in both vertebrate groups. However, lactate turnover rate and oxidation rate do not scale with body mass in the same fashion as does metabolic rate. The slope of the mammalian relationship for whole-body lactate turnover and oxidation is much lower (0.58) than the slope of the classic relationship for metabolic rate (0.75), indicating that lactate is a much more important oxidative substrate for small than for large animals.

Dominant suppression of adenovirus mediated transformation and insufficiency of p105Rb binding as a condition for oncogenic transformation

An adenovirus-specific transformation resistant cell line (G2) expressing biologically active E1a proteins and originally isolated as a revertant from Ad2-transformed rat cells (F4), was shown to form stable Rb-E1a and 300K-E1a complexes in immunoprecipitation experiments. Consistent with the transformation resistant phenotype, cell hybrids between G2 and F4 were all nontumorigenic. Retrovirus insertion mutagenesis resulted in tumorigenic cell lines and identified a common locus responsible for the E1a-specific dominant tumor suppressor phenotype of G2 cells.

Laboratory diagnosed human viral infections in Canada, 1980-1988. Trends and clinico-epidemiological characteristics

Between 1980 and 1988, the Laboratory Centre for Disease Control (LCDC) received 261,573 reports of positive laboratory diagnoses of viral and selected nonviral agents from Canadian laboratories for the determination of the distribution of these agents with age, seasonality, periodicity, and symptoms. The agents most frequently associated with diseases of the respiratory and gastrointestinal tracts, skin, and mucous membranes, the eye, and the central nervous system are identified and ranked. The temporal patterns of common enteroviruses and vaccine preventable diseases are also described. New diagnostic techniques, availability of diagnostic services, awareness of the role an agent plays in disease, and real changes in the occurrence of a disease may influence the number of positive laboratory reports.

An erythromycin derivative produced by targeted gene disruption in Saccharopolyspora erythraea

Derivatives of erythromycin with modifications at their C-6 position are generally sought for their increased stability at acid pH, which in turn may confer improved pharmacological properties. A recombinant mutant of the erythromycin-producing bacterium, Saccharopolyspora erythraea, produced an erythromycin derivative, 6-deoxyerythromycin A, that could not be obtained readily by chemical synthesis. This product resulted from targeted disruption of the gene, designated eryF (systematic nomenclature, CYP107), that apparently codes for the cytochrome P450, 6-deoxyerythronolide B (DEB) hydroxylase, which converts DEB to erythronolide B (EB). Enzymes normally acting on EB can process the alternative substrate DEB to form the biologically active erythromycin derivative lacking the C-6 hydroxyl group.

Transformation renders MDR cells more sensitive to polyunsaturated fatty acids

A series of genetically related cell lines that express mdr genes but differ in their ability to form tumors has been challenged with gamma-linolenate and eicosapentaenoate to verify if the sensitivity of tumorigenic mdr cells to cytotoxic PUFAs differs from the sensitivity of non-tumorigenic mdr cells. The tumorigenic mdr cell lines were derived by transformation of their parental non-tumorigenic mdr cell line with myc and ras oncogenes. Four ras and five myc transformed cell lines were used for the estimation of clonal variability. The data as based on colony forming assays, showed that six out of nine of the tumorigenic mdr cell lines were more sensitive than the non-tumorigenic mdr cells. These results suggest that a tumorigenic phenotype renders mdr cells more sensitive to PUFAs and that PUFA supplementation either alone or in conjunction with existing forms of cancer therapy may have significant clinical implications.

Adenovirus type 2 precursor proteins are cleaved by proteinases of other adenoviruses

A virus-encoded endoproteinase is responsible for the cleavage of adenovirus type 2 (Ad2) precursor proteins. By analyzing the genetic maps of previously characterized interserotypic recombinants between Ad2 and Ad5 and by means of an in vitro proteinase assay using Ad1, 2, 3, 4, 5, 6, 7, 9 as the source of enzyme, it was demonstrated that (i) the enzyme was present in these serotypes and by extension it is likely to be present in all adenoviruses, and (ii) that proteolytic cleavage can take place efficiently even between widely different serotypes. These attributes suggest a high degree of sequence conservation of the enzyme and substrate cleavage sites, thus designating proteolytic processing as an excellent target for chemotherapy.

Annual rotavirus epidemic patterns in North America. Results of a 5-year retrospective survey of 88 centers in Canada, Mexico, and the United States. Rotavirus Study Group

Rotavirus is the major cause of severe diarrhea in children. A recent study of hospitalizations for diarrhea in the United States suggested that the annual rotavirus epidemic may follow a regional sequence from west to east. As part of a program to establish active surveillance of rotavirus prior to the introduction of vaccines, we obtained 5 years of retrospective data on rotavirus detections from 88 centers throughout North America. Analysis of 34,644 detections indicates that the peak of the annual rotavirus epidemic occurs first in Mexico and the Southwest of the United States in late fall, goes systematically across the continent in the winter, and ends in the Northeast United States and the Maritime Provinces of Canada in the spring. When detections are grouped by region, onset of the epidemic follows the same regional sequence as the peak. To our knowledge, this is the only description of a repetitive geographic sequence for the seasonal epidemic activity of a viral agent. Further studies are indicated to determine whether climate, features of the virus itself, or other factors are responsible for this apparently unique pattern. A system of active surveillance can use this pattern to detect natural alterations in the epidemic behavior of rotavirus and to assess the impact of vaccines.

Retransformation of a revertant cell line with the adenovirus E1 oncogenes and vanadate

We have isolated a revertant cell line (G5) from an adenovirus transformed rat cell line (F4) which failed to express the integrated viral oncogenes. To determine whether the reversion mutation was acting in cis or trans the G5 cells were co-transfected with an E1 gene bearing expression plasmid and a neomycin phosphotransferase bearing plasmid. G418-resistant colonies were picked and shown to express the E1 proteins and to be tumorigenic. This re-transformation could be partially mimicked by treatment with vanadate, an inhibitor of phosphotyrosine phosphatases. These results show that the continued presence of the E1 proteins was required to maintain the transformed phenotype, and that the reversion mutation was a cis-acting event affecting directly the integrated E1 genes.

Cloning of genes involved in erythromycin biosynthesis from Saccharopolyspora erythraea using a novel actinomycete-Escherichia coli cosmid

Two plasmids were constructed that replicate in Saccharopolyspora (Sac.) erythraea, Escherichia coli and Streptomyces (S.) lividans, and used for the cloning of a locus involved in the synthesis of the macrolide antibiotic erythromycin (Er). Plasmid pAL7002 contains the thiostrepton-resistance gene (tsr), a replicon-containing fragment from pJVI and pUC9. Plasmid pNJI contains the lambda cos site but is otherwise similar to pAL7002. A library of total DNA from Sac. erythraea was constructed in pNJI and probed in colony hybridizations with a DNA fragment containing ermE, the Sac. erythraea ErR-encoding gene. Plasmids obtained were subsequently introduced into EryA mutants of Sac. erythraea blocked in synthesis of Er (Ery-) and transformants were screened for restoration of Er production (Ery+). Several plasmids were found to convert two mutants to Ery+, but a third EryA strain could not be restored to Ery+ by any of the plasmids employed. A 5-kb segment, designated eryAI, responsible for restoring the Ery+ phenotype in the EryA strains, was identified and mapped in the segment 12 to 17 kb downstream from ermE. Gene disruption experiments indicated that the 5-kb length of eryAI is fully internal to an eryAI-containing transcript. In Southern blots it was shown that one of the EryA strains carried a small deletion in eryAI and that, in at least some of the transformants restored to Ery+, the deletion had been replaced by the wild-type eryAI allele.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of the glucose cycle in control of net glucose flux in exercising humans

The hepatic glucose cycle involves the production of plasma glucose from glucose 6-phosphate and the simultaneous conversion of glucose back to glucose 6-phosphate. We have evaluated the role of the glucose cycle in the regulation of plasma glucose concentration during exercise at 70% of maximal O2 uptake and during recovery in five normal volunteers. Total glucose flux was measured by use of [2-2H]glucose (Ra2), net glucose flux through the glucose cycle was determined with [6,6-2H2]glucose (Ra6), and the rate of glucose cycling was determined by Ra2 - Ra6. Gas chromatography-mass spectrometry was used for analysis of isotopic enrichment. At rest, 33% of total glucose flux was recycled. In exercise, total flux increased 300%, but so did glucose cycling, which means that there was no change in the percentage of flux recycled. In recovery, both total flux and the rate of recycling returned rapidly to the resting value. We therefore conclude that whereas total glucose production can respond extremely quickly to large changes in energy requirements caused by exercise, thereby enabling maintenance of a constant blood glucose concentration, glucose cycling does not have an important role in amplifying the control of net hepatic glucose flux through the glucose cycle.

Organization of a cluster of erythromycin genes in Saccharopolyspora erythraea

We used a series of gene disruptions and gene replacements to mutagenically characterize 30 kilobases of DNA in the erythromycin resistance gene (ermE) region of the Saccharopolyspora erythraea chromosome. Five previously undiscovered loci involved in the biosynthesis of erythromycin were found, eryBI, eryBII, eryCI, eryCII, and eryH; and three known loci, eryAI, eryG, and ermE, were further characterized. The new Ery phenotype, EryH, was marked by (i) the accumulation of the intermediate 6-deoxyerythronolide B (DEB), suggesting a defect in the operation of the C-6 hydroxylase system, and (ii) a block in the synthesis or addition reactions for the first sugar group. Analyses of ermE mutants indicated that ermE is the only gene required for resistance to erythromycin, and that it is not required for production of the intermediate erythronolide B (EB) or for conversion of the intermediate 3-alpha-mycarosyl erythronolide B (MEB) to erythromycin. Mutations in the eryB and eryC loci were similar to previously reported chemically induced eryB and eryC mutations blocking synthesis or attachment of the two erythromycin sugar groups. Insertion mutations in eryAI, the macrolactone synthetase, defined the largest (at least 9-kilobase) transcription unit of the cluster. These mutants help to define the physical organization of the erythromycin gene cluster, and the eryH mutants provide a source for the production of the intermediate DEB.

Adenovirus proteinases: comparison of amino acid sequences and expression of the cloned cDNA in Escherichia coli

Adenoviruses (Ad) synthesize serine-center endoproteinases (AdEPs) responsible for maturation cleavages within the virus particle. Many questions regarding these enzymes remain unanswered because previous studies utilized crude cells or viral lysates as the enzyme source. Here, we report on the comparison of the amino acid (aa) sequences of several AdEPs and on the expression of the cDNA of the Ad2Ep in Escherichia coli. The AdEPs consist of about 200 aa and their size is around 23 kDa. Among the seven sequences known, 60% of aa were strictly conserved. The usual serine proteinase active site sequence, GDSGG, is absent. The recombinant Ad2EP, produced by an inducible vector as a protein-A fusion product is capable of autocatalytic cleavage, and of cleaving its natural viral substrates as well as foreign proteins. Therefore, other viral proteins or mammalian specific post-translational modifications are not required for enzyme activity.