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Biomedical subjects

M Roberts

Publications and source records attributed to M Roberts.

At least 307 records · Page 17Linked to original sources
PubMed1982

Molecular characterization of three chloramphenicol acetyltransferases isolated from Haemophilus influenzae.

Three plasmid-mediated chloramphenicol acetyltransferases isolated from different Haemophilus influenzae strains were purified and characterized. All three enzymes had properties in common with the gram-negative family of chloramphenicol acetyltransferase. The Haemophilus enzymes and the enteric type II enzyme were sensitive to 5,5'-dithiobis(2-nitrobenzoic acid), gave the same elution patterns from a highly substituted resin containing a bound chloramphenicol base, and had similar reactions to antisera. All four differed from each other in subunit molecular weight, enzyme activity, and partial protein digestion patterns. The data suggest that the three Haemophilus enzymes belong to the less common type II group and are related, but is not identical, to each other and to the enteric type II enzyme.

Acetyltransferases↗
PubMed1982

Bronchopulmonary torulopsosis.

A patient had clinical and radiographic findings suggestive of allergic bronchopulmonary aspergillosis. Further studies excluded this diagnosis but indicated that the patient's respiratory disease was due to the yeast Torulopsis glabrata, usually nonpathogenic in normal human hosts. The patient had no evidence of invasive disease. Total serum IgE was elevated but IgE antibody against T. glabrata could not be demonstrated by skin test or radioimmunoassay. Demonstration of elevated IgG antibody against T. glabrata antigen by radioimmunoassay was of value in suggesting the diagnosis. The patient responded to prednisone therapy with clinical and radiographic improvement and with a sharp decline in total serum IgE, and a lesser degree of decline in total serum IgG and IgA. Bronchopulmonary torulopsosis may be rare but should be considered in cases where the diagnosis of allergic bronchopulmonary aspergillosis cannot be established. Because IgE antibody could not be incriminated in this disease the term allergic bronchopulmonary torulopsosis was not used in this case.

Aged↗
PubMed1982

Allergic bronchopulmonary aspergillosis: staging as an aid to management.

Five stages of allergic bronchopulmonary aspergillosis were identified in 40 patients studied for several years. The stages are acute, remission, exacerbation, corticosteroid-dependent asthma, and fibrotic. The acute stage has all criteria of the disease and responds to prednisone. The remission stage is free from significant asthma or exacerbations. The exacerbation stage has recurrent flares of acute allergic bronchopulmonary aspergillosis. The corticosteroid-dependent asthma stage may have recurrent exacerbations of allergic bronchopulmonary aspergillosis and severe asthma. The fibrotic stage is an advanced stage of radiographic abnormalities with asthma, irreversible and partially reversible obstructive pulmonary function changes, and poor prognosis. Measurement of IgE and IgG antibodies against Aspergillus fumigatus is of diagnostic value in all stages.

Acute Disease↗
PubMed1981

Hypersensitivity lung disease presumptively due to Cephalosporium in homes contaminated by sewage flooding or by humidifier water.

Two cases of hypersensitivity lung disease apparently caused by home environment contamination with Cephalosporium have been identified. In one case repeated flooding of the home with sewer water appeared to be important in maintaining an environment contaminated with Cephalosporium, and in the other case a contaminated humidifier appeared to be the source. Both patients had chronic respiratory symptoms remitting during absence from the home, and both presented problems in diagnosis. In both cases cultures of the home environment or humidifier and serum antibody studies indicated Cephalosporium as the antigenic source responsible for the airway disease. An inhalation challenge in one case was positive, adding further evidence for Cephalosporium as the antigenic source and etiologic agent. In both cases complete remission followed moving from the home. Cephalosporium is reported as an apparent antigenic source for home contamination resulting in significant chronic pulmonary morbidity.

Acremonium↗
PubMed1981

Rapid detection of chloramphenicol resistance in Haemophilus influenzae.

We compared a rigid (1-h) screening method for the detection of chloramphenicol acetyltransferase (CAT) activity with the standard spectrophotometric CAT assay to determine whether CAT-mediated chloramphenicol resistance in Haemophilus influenzae could be determined upon primary isolation. Of 58 H. influenzae cell sonicates, 28 had detectable CAT activity when the chloramphenicol-dependent production of free coenzyme A from acetyl coenzyme A was measured spectrophotometrically (standard method). These 28 strains were identified as producing CAT by the rapid method which uses lysed cell suspensions and a color change to detect CAT. The remaining 30 strains did not have CAT activity detectable by either method. This 1-h test for CAT should prove to be useful for the early presumptive identification of chloramphenicol resistance in H. influenzae.

Acetyltransferases↗
PubMed1981

Comparative virulence of Haemophilus influenzae with a type b or type d capsule.

To determine the importance of specific capsule type in the pathogenesis of invasive Haemophilus influenzae disease, we compared the virulence of type b and type d strains isolated from different children with the virulence of transformation-derived type b and type d organisms. In addition, the unencapsulated derivative of these strains was also examined. Virulence was assessed by determining the ability of the strains to produce bacteremia with intranasal or subcutaneous inoculation. Unencapsulated derivatives were unable to cause bacteremia by any route; all type b strains (whether natural or derived by transformation), a natural type d, and a type d derived by transformation were able to produce bacteremia with similar frequency (42 to 62%) when 10(7) colony-forming units was given intranasally. Subcutaneous inoculation of 10(3) colony-forming units of strains with the type b capsule produced bacteremia at a greater frequency than did the strains with the type d capsule (P less than 0.002). The type d isolate was more virulent than a mutagenized derivative of the strain. We conclude that the type b strains are more virulent than type d when inoculated subcutaneously.

Animals↗
PubMed1981

Branhamella (Neisseria) catarrhalis--a lower respiratory tract pathogen?

Branhamella (Neisseria) catarrhalis was identified as a probable respiratory tract pathogen in seven patients, four with pneumonia and three with bronchitis. Five of the B. catarrhalis isolates produced beta-lactamase. Production of beta-lactamase correlated with penicillin resistance by the standardized disk diffusion method and also with high minimal inhibitory concentrations of penicillin for the two strains which were tested.

Aged↗
PubMed1981

Seasonal variation of IgE antibody specific for ragweed antigen E (IgE-a-AgE) from the basophil surface in patients with ragweed pollenosis.

Seasonal elevation in total serum IgE and IgE antibody specific for antigen E (IgE-a-AgE) are well recognized in patients with ragweed pollenosis. We found that the ratio of specific IgE-a-AgE to total IgE in plasma was the only measure predictive of the number of specific IgE-a-AgE molecules per basophil. Although both total and specific IgE rose with season, the ratio did not change, the number of IgE-a-AgE molecules per basophil did not change, and histamine release in response to AgE did not increase.

Antibody Specificity↗
PubMed1981

Human antibodies against trimellityl proteins: comparison of specificities of IgG, IgA and IgE classes.

The specificities of antibodies of different Ig classes against trimellityl (TM)-human serum albumin were examined by a radioimmunoassay inhibition technique. The antisera were from workers exposed to trimellitic anhydride who had 4 differing respiratory diseases. The studies demonstrated similarities between reactivities of antibodies of different Ig classes in these workers in that inhibition of antibody to TM-HSA required markedly less TM-HSA on a molar basis than TM-ovalbumin (OA) or sodium trimellitate (NaTM), the hapten for the trimellityl group. The results appears best explained by formation of new antigenic determinants on altered HSA molecules with the TM group forming a component of some of the new antigenic determinants. NaTM in high concentration could not completely inhibit the IgG antibodies of 2 sera suggesting either very low affinity for the hapten or that some of the antibodies might possibly be directed against new antigenic determinants formed from the reaction of TMA with HSA but that the TM group might not be a part of the antigenic specificity. The results of some studies also suggested that there were similar antigenic specificities on TM-HSA and TM-OA but of lesser concentration or lower affinity on the latter molecules. Passive transfer studies using a serum containing IgE antibodies against TM-HSA demonstrated that these human IgE antibodies will passively sensitize rhesus monkey skin. Neutralization of the cutaneous IgE antibodies occurred with TM-HSA but not with a great molar excess of NaTM in analogy with the in vitro studies.

Antibodies↗