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Biomedical subjects

A W Smith

Publications and source records attributed to A W Smith.

At least 91 records · Page 5Linked to original sources
PubMed1991

Immune response to Acinetobacter calcoaceticus infection in man.

After growth in an iron-depleted chemically-defined medium Acinetobacter calcoaceticus expressed four high mol. wt outer-membrane proteins (OMPs) which were repressed under iron supplementation or in a complex laboratory medium. Immunoblotting with serum from a septicaemic patient infected with A. calcoaceticus revealed antibody binding to these iron-repressible OMPs, indicating that they were expressed in vivo, and also to the 42- and 18-Kda OMPs. Although the antibody response to the OMPs did not vary significantly during convalescence, the response to the O-polysaccharide component of lipopolysaccharide decreased significantly. However, antibodies in serum from patients with A. calcoaceticus wound infections reacted with the iron repressible OMPs and a 54-Kda antigen suggesting a difference in immune recognition between local and systemic infection.

Acinetobacter↗
PubMed1991

Diversity of pilin of serologically distinct Bacteroides nodosus.

Pili from 11 distinct serotypes of Bacteroides nodosus were examined for diversity of pilin polypeptide subunits among serotypes and for purity of the pilin preparations. The pilin of all 11 samples was shown to be homogeneous. Mean +/- SD molecular weight of the pilin of 7 serotypes (A198, IV, V, VI, IX, XVII, and XVIII) was 18,500 +/- 100. The pilin of serotypes I, III, and VIII had molecular weight of 17,600, 19,400, and 19,000, respectively. Serotype XV differed greatly from the other 10 serotypes in that 2 distinct polypeptide bands with molecular weight of approximately 7,800 and 6,200 were detected. We suggest that these 2 low molecular weight bands resulted from proteolytic cleavage of the pilin protein.

Bacteroides↗
PubMed1991

Electron microscopic study of Bacteroides nodosus pili and associated structures.

Surface structures of Bacteroides nodosus were examined by electron microscopy. Collodion film and chrome shadowing were used for maximizing the visualization of B nodosus pili and ring structures. The existence of B nodosus pili in foot rot lesions was confirmed. Contrary to previous reports, it was found that B nodosus pili production can be retained through serial broth transfer under certain conditions. Capsule production by B nodosus was irregular in that it could be either lacking or variable in thickness. A bacteriophage capable of infecting B nodosus also was detected.

Animals↗
PubMed1991

Monoclonal antibodies against pili of serologically distinct Bacteroides nodosus.

Several monoclonal antibodies (McAbs) against pili of Bacteroides nodosus were examined to determine their reactivity with 11 different serotypes. One McAb was identified by enzyme-linked immunosorbent assay (ELISA) analysis that bound to nine of the 11 serotypes and another that bound to the remaining two serotypes tested. In addition, some McAbs demonstrated specificity for a single serotype, while others displayed specificities for up to five other serotypes. Comparison of immunoblot analysis with the ELISA revealed that the former method was not as sensitive in that all McAbs positive by the ELISA, were not positive by immunoblot. Possible explanations of these findings are discussed. There appear to be several antigenic determinants on B. nodosus pili and considerable sharing of these determinants between pili types. The 11 serotypes analyzed by the McAbs in this report are representative of all 20 US serotypes as well as the A-set and D-set categories of Australia. Therefore, the two epitopes recognized by two of the McAbs reported herein encompass all of the currently characterized B. nodosus serotypes and may provide a basis for bivalent vaccines efficacious for all types of B. nodosus induced footrot in sheep.

Animals↗
PubMed1990

Characterisation of a siderophore from Acinetobacter calcoaceticus.

The Gram-negative bacterium Acinetobacter calcoaceticus was examined for production of siderophores and iron-repressible outer membrane proteins following growth in iron-restricted media. The iron chelator, 2,3-dihydroxybenzoic acid was identified in the culture supernatant by 1H nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). A group of outer membrane proteins between 80 and 85 kDa were induced under iron restriction.

Acinetobacter↗
PubMed1990

Regulation of isopenicillin N synthetase (IPNS) gene expression in Acremonium chrysogenum.

Total RNA was extracted daily from the beta-lactam antibiotic producing fungus A. chrysogenum strain CO728 during a 7 day cephalosporin C fermentation. IPNS mRNA species, with a size of about 1.5 kb, were detected by Northern blotting at high levels between days 2 and 4. The rapid appearance of IPNS mRNA in mycelial extracts up to day 2 suggests that IPNS is regulated at the transcriptional level. Primer extension and S1 endonuclease mapping studies indicate the existence of two major and at least two minor transcription initiation start sites. There was no change in the relative levels of the four transcripts during the period they could be detected. A region upstream of the IPNS structural gene (pcbC) has been sequenced and the transcription initiation sites appear as major and minor pairs on either side of one of the pyrimidine-rich blocks that punctuate the promoter sequence.

Acremonium↗
PubMed1990

New marine calicivirus serotype infective for swine.

A new serotype of calicivirus was isolated from California sea lions (Zalophus californianus) with severe vesicular disease. Neutralizing antibodies were found in 27 of 82 (32.9%) serum samples from California sea lions and in 15 of 146 (10.3%) serum samples from Steller sea lions (Eumetopias jubatus) tested. The seropositive animals were widely dispersed along the margins of the eastern Pacific basin, from the Bering Sea to the Santa Barbara Channel. Seropositive samples were found from as early as 1976 through the present time. This new calicivirus serotype, San Miguel sea lion virus type 13, was inoculated into weaned pigs, resulting in induction of severe vesicular disease, which spread to all pigs, including uninoculated pen contacts. Virus was continually shed by most of the pigs throughout the 2-week duration of the experiment.

Animals↗
PubMed1990

Sultamicillin (sulbactam/ampicillin) versus amoxycillin in the treatment of acute otitis media in children.

A comparative study of sultamicillin (an orally active dimer of sulbactam and ampicillin) and amoxycillin for the treatment of acute otitis media was carried out in 86 children with acute otitis media. After 10 days' treatment, of those with traditional middle ear pathogens, 35/36 (97%) 50 mg/kg.day or 500 mg/day sultamicillin-treated children were cured with eight relapses after a further 18 days without treatment compared with 12/13 (92%) 40 mg/kg.day or 250 mg/day amoxycillin-treated children and three subsequent relapses. All six beta-lactamase-producing pathogens were in the sultamicillin treatment group: four were Haemophilus influenzae/H. parainfluenzae that were resistant to amoxycillin, and all were cured although two then relapsed. No significant clinical or laboratory side-effects were noted in either amoxycillin- or sultamicillin-treated patients. It is concluded that sultamicillin was comparable to amoxycillin in the treatment of acute otitis media.

Acute Disease↗
PubMed1989

Iron-deficiency anaemia and its response to oral iron: report of a study in rural Gambian children treated at home by their mothers.

Haematological and iron parameters, measured in 907 children aged from 6 months to 5 years in rural Gambia at the start of the rainy season, differed from those in American reference populations as follows: mean haemoglobin levels were much lower at ages 1 and 2 years and mean levels of mean corpuscular volume (MCV) were lower at all ages (at age 1 year mean haemoglobin was 11.2 g/dl and mean MCV 68.2 fl); in a sample of 249 children randomly selected from the whole study population, mean serum iron levels were similar but mean transferrin saturation and mean serum ferritin levels were lower, especially at ages 1-3 years (at age 1 year mean serum iron was 11.1 mumol/l, mean transferrin saturation 16.9%, and geometric mean serum ferritin 8.8 ng/ml. A total of 213 children (23%) whose haemoglobin and mean corpuscular volume were both less than the 3rd percentile of the reference population received oral iron or placebo from their mothers during the rainy season when malaria transmission is maximal. Mean levels of haemoglobin, mean corpuscular volume, serum iron, transferrin saturation and serum ferritin rose in the iron-treated group and fell in the placebo group at all ages, except under 1 year for serum ferritin, to produce significant differences between the groups by the end of the study. Total iron-binding capacity showed no significant changes during the study. We concluded that oral iron given by the mother during the rainy season can be used to treat iron-deficiency anaemia in Gambian children who would otherwise become more anaemic.

Administration, Oral↗
PubMed1989

The effects on malaria of treatment of iron-deficiency anaemia with oral iron in Gambian children.

In order to determine whether giving iron to iron-deficient children increases their susceptibility to malaria, 213 Gambian children aged between 6 months and 5 years with iron-deficiency anaemia were randomized to receive either oral iron or placebo during the rainy season when malaria transmission is maximal. Haematological and iron measurements improved significantly in the group given iron. Regular morbidity surveys showed that fever associated with parasitaemia occurred more frequently in the iron-treated group than in the placebo group. This difference was not significant for all parasitaemias grouped together, but became significant and progressively larger for parasitaemias of ten or more positive fields per 100 high power fields (P less than 0.025), and for parasitaemias of 50 or more positive fields per 100 high power fields (P less than 0.01). Three children in the iron-treated group but none in the placebo group had more than one episode of fever and parasitaemia. Splenomegaly rates rose appreciably during the study in both groups, but in children at age 2 years the splenomegaly rate at the end of the study was significantly greater in the iron-treated group. We concluded that there is a significantly increased risk of fever associated with severe malarial parasitaemia for children with iron-deficiency anaemia given iron during the season of maximal malaria transmission in this part of The Gambia.

Administration, Oral↗
PubMed1989

Effectiveness of vaccination in controlling ovine footrot.

Efficacy of reducing footrot by use of a commercial vaccine was evaluated over 2 yr with 223 ewes from five crossbred genotypes. Ewes were assigned randomly within genotype, age and initial footrot status to a 2 x 3 factorial array of vaccination in the 1st yr and fall vaccination, winter vaccination or control in the 2nd yr. The flock contained a single Bacteroides nodosus serotype (XV) known to be highly cross-reactive with one of the vaccine serotypes (British serotype H). Vaccination reduced footrot incidence by 61% (P less than .01) in the 1st yr and by 45% (P less than .01) in the 2nd yr. Vaccination of previously uninfected ewes did not significantly reduce the rate of new infection, but vaccination of infected ewes reduced re-infection by 92% (P less than .01). Vaccination in the 1st yr failed to produce any carryover or additive protection in the 2nd yr. Genotypes differed in both footrot incidence (P less than .05) and footrot reduction following vaccination (P less than .05), but the effect was inconsistent between years. Vaccination increased serum antibody titers in both years (P less than .01). Among vaccinates in the 1st yr, infected ewes had lower titer levels than uninfected ewes (P less than .01), but no correlation between titer level and incidence was observed in the 2nd yr.

Animals↗
PubMed1989

Mortality of harbor seal pups at different sites in the inland waters of Washington.

We examined the mortality rates and causes of death of harbor seal (Phoca vitulina) pups in three regions of the inland waters of Washington (USA) in 1984. One hundred eight pups were collected during 239 searches of the shoreline areas near harbor seal haulout sites or through public reports. Minimum neonatal (up to 1 mo after birth) mortality rates at these regions ranged from 12% to 26% of the pups born. Neonatal mortality was highest in the Strait of Juan de Fuca; 33 of the estimated 105 (31%) pups born at the primary site died. Causes of death varied by location. In southern Puget Sound predation by coyotes (Canis latrans) was the primary cause of death, accounting for eight of 43 (19%) of the dead pups examined; starvation was the next most common cause of death. Mortality at study sites in the Strait of Juan de Fuca was related to premature parturition; 19 of 49 (39%) of the pups found dead were born prematurely. Nine species of bacteria were identified in samples taken from 42 pups; Proteus sp. and Escherichia coli were the most common.

Animals↗
PubMed1988

Euthanasia.

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Animals↗
PubMed1988

Sequelae of epidemic meningococcal meningitis in Africa.

Audiological and other long-term neurological sequelae were determined in 157 cases and their controls matched for age, sex and village 6 to 12 months after an epidemic of group A meningococcal meningitis in rural West Africa. 19 cases (12.1%) and 3 controls (1.9%) had moderate or severe neurological sequelae of any type (P less than 0.001); 6 cases (3.9%) and no controls had severe or profound sensorineural hearing loss (P = 0.03). There was no difference in conductive hearing loss between cases and controls. Other cranial nerve sequelae (except visual defects) and generalized neurological and motor and co-ordination sequelae were also significantly increased in cases. Sensorineural hearing loss and other cranial nerve sequelae occurred significantly more frequently in males than in females, and co-ordination sequelae more frequently in cases aged 10 years or more than in younger cases. Sensorineural hearing loss and loss of visual acuity were found significantly more frequently in cases whose treatment was delayed for 4 d or more, compared with those who received treatment sooner.

Adolescent↗
PubMed1988

Photoreactivation in phr mutants of Escherichia coli K-12: cloning from the gal-att lambda interval increases the photoreactivable response in phrA strains.

In this report we have cloned restriction fragments from the gal-att lambda region obtained from a purified preparation of lambda dgal transducing 'phage DNA, and demonstrate the appearance of a photoreactivable response in a photoreactivation-deficient phrA phrB strain. We also show that when this plasmid is transduced into a delta phrA strain there is an increase in the photoreactivable response after a single high intensity light flash and after continuous illumination. These data have been discussed in relation to the hypothesis of the presence of multiple photolyase molecules in Escherichia coli.

Bacteriophage lambda↗