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Biomedical subjects

M Roberts

Publications and source records attributed to M Roberts.

At least 271 records · Page 15Linked to original sources
PubMed1987

Incidence of the aerobactin iron uptake system among Escherichia coli isolates from infections of farm animals.

To assess the importance of aerobactin-mediated iron uptake as a bacterial virulence determinant in animal infections, a total of 576 strains of Escherichia coli isolated from cattle, chickens, sheep and pigs were screened by colony hybridization to determine the presence of the aerobactin genetic determinants, and by a bioassay to detect aerobactin secretion in iron-limited conditions. Results obtained by the two complementary methods correlated well. The incidence of the aerobactin system was very high among septicaemia isolates, particularly those from cattle and chickens, an observation that strongly suggests an important role for this mechanism of iron assimilation in pathogenesis. On the other hand, the incidence of the aerobactin system among mastitis strains was not significantly higher than among faecal isolates from healthy animals. No classical enterotoxigenic E. coli strains tested carried the aerobactin genetic determinants. Although most strains that produced aerobactin were also able to make colicin V, the fact that the two characteristics existed separately in a significant minority of isolates suggested that colicin testing alone could not be reliably used to determine the presence of the aerobactin system.

Animals↗
PubMed1987

Determinants of chronic bronchitis and lung dysfunction in Western Australian gold miners.

The relation of chronic bronchitis and respiratory dysfunction to age, tobacco smoking, and occupational exposure to surface and underground mining operations were examined in a cross sectional survey of 1363 men employed in the Kalgoorlie mining industry in 1985. Overall, the prevalence of chronic bronchitis was 14%. Eleven per cent of the workers had obstructive lung disorder (FEV1/FVC less than 0.70) and 9% had restrictive lung disorder (FVC less than 0.80 of predicted for height and age). There was little change in the prevalence of chronic bronchitis from that observed in a survey of the same industry in 1961-2. Only 1% of the workers in 1985 had radiographic signs of silicosis compared with 22% in 1961-2. Age, smoking, and underground mining experience all exerted strong effects on the development of chronic bronchitis with or without associated respiratory function abnormalities. After control of confounding by age and smoking, it was estimated that compared with a lifetime non-miner, the odds ratio (OR) of chronic bronchitis was 1.8 (95% confidence interval, 1.0-3.3) for one to nine years underground mining gold, 2.5 (1.2-5.2) for 10-19 years, and 5.1 (2.4-10.9) for 20 or more years. Underground mining of minerals other than gold was also associated with chronic bronchitis (OR = 5.1; 95% CI, 1.1-25.0) whereas exclusive surface mining had only a small empirical effect (OR = 1.3; 95% CI, 0.6-2.5). It is estimated that the proportion of cases of chronic bronchitis in working underground miners due to occupational factors is 50%. The results support the existence of an industrial cause of chronic bronchitis, although caution must be exercised in generalising the results to miners with progressive and sever respiratory impairment.

Adolescent↗
PubMed1987

The Bowie/Dick test: an alternative way.

Since notification from the DHSS that the Lantor Cube (DHSS 1986) has been accepted, and approved as equivalent to the towel pack for the daily Bowie and Dick testing of porous load autoclaves, considerable interest has been shown in cost comparison between the Lantor cube and the towel pack.

Central Supply, Hospital↗
PubMed1987

Specificity of immunoglobulin E and immunoglobulin G against human (recombinant DNA) insulin in human insulin allergy and resistance.

Using an enzyme-linked immunosorbent assay method, we have demonstrated immunoglobulin E (IgE) and immunoglobulin G (IgG) against human (recombinant DNA) insulin in serum samples of a patient whose insulin therapy was only with human insulin. Within 12 days of initiation of human insulin for gestational diabetes, large local reactions developed in the patient in association with high levels of IgE to human insulin. As the local reactions subsided, the levels of IgE to human insulin decreased. The patient's insulin requirement was unusually high for pregnancy and tended to decrease in parallel with falling levels of IgG to human insulin, suggesting an element of immunologic insulin resistance. In addition to IgE and IgG against human insulin, we were able to demonstrate the presence of IgE and IgG against porcine and bovine insulin in the serum samples of this patient. The patient had similar immediate cutaneous reactivity to each insulin. In inhibition studies, similar amounts of porcine insulin, bovine insulin, or human insulin were found to produce 50% inhibition of human insulin binding to IgE or IgG against human insulin. Excess porcine insulin or bovine insulin resulted in total inhibition of human insulin binding to IgE or IgG. Thus even in a patient whose initial form of insulin therapy was human insulin, there was development of insulin allergy and of IgG to human insulin that may have contributed to insulin resistance. Moreover, the antigenic determinants recognized by antibody induced by human insulin may also be present on bovine insulin and porcine insulin as demonstrated in this case.

Adult↗
PubMed1987

Stage V (fibrotic) allergic bronchopulmonary aspergillosis. A review of 17 cases followed from diagnosis.

A review of the records of 17 patients with stage V (fibrotic stage) allergic bronchopulmonary aspergillosis observed since initial diagnosis (mean observation period, 4.9 years) demonstrated that, of the 11 surviving patients, four have very severe respiratory impairment. The other seven patients have mild or moderate functional impairment, but most of these have not shown clinical deterioration during the observation period. The occurrence of new roentgenographic infiltrates after the time of diagnosis was observed in only one patient in this series. Serum IgE and IgG levels against Aspergillus fumigatus, when compared with those of a control pool of serum samples from asthmatic patients with immediate cutaneous reactivity to Aspergillus, were the most useful immunologic studies diagnostically. Lung biopsy specimens obtained in five patients were of relatively little diagnostic value. All patients have required long-term prednisone therapy for control of asthma. Those patients whose forced expiratory volume in 1 s (FEV1) remained less than or equal to 0.8 L after initial corticosteroid treatment demonstrated a poor prognosis. When only moderate lung damage has occurred at the time of diagnosis, a stable subsequent course may be expected even in patients with stage V disease.

Adult↗
PubMed1986

Allergic bronchopulmonary aspergillosis. Natural history and classification of early disease by serologic and roentgenographic studies.

Eighty-four patients with allergic bronchopulmonary aspergillosis (ABPA) were evaluated for a total of 294 patient-years with a mean observation period of 3.7 years and classified by the stage of ABPA. The largest percentage of patients were in the stage IV (corticosteroid-dependent asthma stage) group. The next largest percentage were in the stage V (fibrotic, end-stage lung disease) group. Of the latter 24 patients, eight had died. In addition, we describe 13 patients with all serologic characteristics of ABPA but without central bronchiectasis. We propose that these patients have seropositive ABPA and represent the earliest cases of it that can be diagnosed in contrast with ABPA with central bronchiectasis in which lung damage is already present.

Adrenal Cortex Hormones↗
PubMed1986

Ethylene oxide (ETO) as a possible cause of an allergic reaction during peritoneal dialysis and immunologic detection of ETO from dialysis tubing.

An infant with end-stage renal disease requiring continuous ambulatory peritoneal dialysis (CAPD) had a cutaneous eruption with eosinophilia. This reaction was not associated with any drug administration. An analysis for antibodies against ethylene oxide-human serum albumin (ETO-HSA) was conducted because IgE antibodies have been correlated with allergic reactions during hemodialysis. IgE and IgG antibodies against ETO-HSA were demonstrated in one of two serum samples available. Serologic evidence is presented that ETO may be eluted from the dialysis tubing, react with HSA in the peritoneum, and immunize the dialyzed host. This may be a possible explanation for allergic manifestations in our patient and others undergoing peritoneal dialysis.

Antibodies↗
PubMed1986

Molecular cloning of amikacin resistance determinants from a Klebsiella pneumoniae plasmid.

A multiresistant Klebsiella pneumoniae strain, JHCK1, harbored several plasmids. One of these, plasmid pJHCMW1, carried determinants for resistance to amikacin in addition to kanamycin, tobramycin, and ampicillin. The amikacin resistance determinant(s) was cloned and studied by restriction mapping, insertion, and deletion analysis. The amikacin resistance gene(s) was localized in a 1.5-kilobase DNA fragment. This pJHCMW1 DNA region was responsible for not only the resistance to amikacin but also the resistance to kanamycin and tobramycin. The cloned DNA fragment specified both an acetyltransferase activity and a low level of phosphotransferase activity. The two activities were absent from mutants that did not confer resistance to amikacin, kanamycin, and tobramycin.

Acetyltransferases↗
PubMed1986

RNA-DNA hybridization analysis of transcription of the plasmid ColV-K30 aerobactin gene cluster.

Plasmid pABN1 contains the genetic determinants for the aerobactin iron uptake system of plasmid ColV-K30. Transposon Tn1000 mutants of pABN1 defective in synthesis of a 50,000-dalton polypeptide were found neither to secrete nor to accumulate aerobactin, but were not impaired in iron transport functions, clearly indicating a role for this polypeptide in aerobactin biosynthesis. RNA-DNA hybridization studies with probes spanning the entire aerobactin gene cluster showed that the system is regulated at the transcriptional level by the availability of iron in the external medium. When induced by low-iron stress, all five genes of the cluster were transcribed at a uniformly high level. When repressed by excess iron, transcripts of the four biosynthesis genes were some 30-fold less abundant in the case of the parental ColV-K30 plasmid and 10-fold less for the recombinant plasmid pABN1, whereas the receptor gene in either plasmid was transcribed at only about a third of the induced level.

Bacterial Outer Membrane Proteins↗
PubMed1986

Recurrent hypercalcaemia in a young man with mono-ostotic Paget's disease.

A 32 year old man presented on two separate occasions with severe hypercalcaemia. Both episodes followed the fracture of a single pagetic bone but were not associated with immobilization. To our knowledge this patient, the youngest described with hypercalcaemia secondary to Paget's disease of bone is also the only reported case of recurrent hypercalcaemia in this condition.

Adult↗
PubMed1986

Comparison of cutaneous and bronchial reactivity to leukotriene D4 in humans.

To establish whether a relationship exists between cutaneous and bronchial reactivity to leukotriene D4 (LTD4), endpoint cutaneous reactivity and bronchial reactivity were determined in six patients with asthma, six patients with seasonal allergic rhinitis, and six nonatopic men. In all subjects, increasing doses of LTD4 produced decreases in specific airway conductance (SGaw) and flow at 30% of vital capacity measured from a partial forced expiratory maneuver (V30P). Intracutaneous injections of LTD4 and histamine resulted in immediate wheal and erythema reactions in all patients. Serial 10-fold dilutions of LTD4 and histamine were injected to establish the lowest dose capable of producing a 4 mm wheal with erythema. Endpoint cutaneous reactivity to LTD4 ranged from 1 mumol to 100 pmol in controls and from 100 nmol to 1 fmol in patients with asthma, but statistically significant differences between groups were not apparent even with inclusion of six additional subjects. No meaningful correlations were found between the quantity of LTD4 producing the threshold cutaneous reaction and the dose of inhaled LTD4 that produced a 35% decrease in SGaw and 30% decrease in V30P. In contrast to the bronchi, where subjects in all three groups were 264 to 840 times more sensitive to LTD4 than to methacholine, 11/18 subjects (3/6 with asthma) were less sensitive to LTD4 than to histamine in terms of endpoint cutaneous reactivity. However, seven of 18 subjects who were more sensitive to LTD4 than to histamine had relative potencies ranging from 5 to 500,000.

Asthma↗
PubMed1986

The status of sorbent technology in hemodialysis treatment.

Twenty years ago an engineer in the aerospace field suggested the possibility of regenerating hemodialysate. This suggestion led to the development of the REDY Sorbent Hemodialysis System. In 1973, when the system was first introduced, the emphasis was on home hemodialysis. This motivation, combined with the relative portability and "no need for plumbing", led to the rapid introduction of the REDY System. Economically, the REDY System has not competed with central systems. However, the REDY System meets a special need for the preparation of individualized dialysate for the chronic and acute renal failure patient. Because of the small volume of the system (6 l), different dialysates can be readily prepared to adjust acid/base balance and normalize electrolyte concentrations. To simplify home hemodialysis, sorbent systems have now become available in which the dialysate side is disposable. This facilitates set-up and eliminates sterilization of the equipment. The Sorbent System can be reduced in size resulting in a continuously wearable hemodialysis system.

Acid-Base Equilibrium↗
PubMed1985

Clinical evaluation of 4-channel ambulatory EEG monitoring in the management of patients with epilepsy.

The role of 4-channel EEG taped monitoring in the management of patients with severe epilepsy has been evaluated, by examining the recordings from 100 consecutive patients referred for monitoring. Six main reasons for referral have been identified and in 80% of subjects the relevant clinical event was recorded, leading directly to a change in treatment in 57% of cases. This technique has proved to be cost effective and reliable and is particularly valuable in the identification of pseudo seizures.

Adolescent↗
PubMed1985

IgE and IgG antibody against human (recombinant DNA) insulin in patients with systemic insulin allergy.

We demonstrated IgE and IgG antibodies to human (rDNA) insulin as well as to bovine and porcine insulin in the serum of two patients with systemic insulin allergy by an enzyme-linked immunosorbent assay. We also demonstrated IgE and total antibody binding to bovine insulin with the use of radioimmunoassays. Both patients had cutaneous reactivity to all three insulins. When the serum of one patient was preincubated with human, porcine, or bovine insulin, there was inhibition of binding of the patient's IgE and IgG antibodies to human insulin. The other patient had very low levels of IgE antibodies to insulin and thus only IgG inhibition was possible. Preincubation with human insulin inhibited binding of each patient's antibodies to bovine or porcine insulin. We conclude that, for these two patients, human insulin has all the antigenic determinants that bovine and porcine insulin have. Therefore, human insulin for these two patients will not eliminate insulin allergy in all patients with systemic allergy to animal insulin, because there are patients whose antibodies recognize determinants common to commercial human, bovine, and porcine insulin.

Adult↗