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Biomedical subjects

D G Brown

Publications and source records attributed to D G Brown.

At least 73 records · Page 4Linked to original sources
PubMed1982

Sleep, scratching and dreams in eczema. A new approach to alexithymia.

6 patients with itching due to skin disorder and 6 student controls were studied in the sleep laboratory. It was found that some of the patients had personality characteristics consistent with Sifneos' concept of alexithymia and that these were associated with a trend towards less REM sleep and with a significant lack of involvement in dreams collected under standardised sleep laboratory conditions. It is suggested that dreams collection in a sleep laboratory may be a valuable new method in the study of the link between emotional life and psychosomatic disorders.

Adolescent↗
PubMed1980

67Gallium scanning in talc-induced pulmonary granulomatosis.

We describe a case of pulmonary granulomatosis in a user who habitually injected methylphenidate (Ritalin) intravenously; symptomatic and objective improvement occurred with corticosteroid therapy. A scan of the lungs using radioactive 67gallium showed an increased concentration of 67gallium throughout both lungs. There was a reduction in abnormal accumulation of 67gallium, improvement in the arterial oxygen pressure and the diffusing capacity for carbon monoxide, and a reduction in the infiltrate on the chest x-ray film two months after the institution of therapy. Before treatment the patient's symptoms and arterial deoxygenation increased despite the cessation of her drug abuse, thus raising the question of a self-perpetuating inflammatory process in a case of pulmonary deposition of talc.

Adult↗
PubMed1980

Performance of bacteria filters.

Several kinds and brands of bacteria filters are commercially available for use in anesthesia and respiratory therapy applications. Clinical experience of high airflow resistance, ruptured media, failure to retain visible dust particles, and lack of consistent performance statements or warranties by manufacturers about their bacteria filters prompted a study of the performance of 13 different filters. The filters were challenged by mineral oil droplets, Serratia marcescens and Excherichia coli bacteriophages T4 and T7, tobacco smoke, nebulized india ink, dioctylphthalate smoke (DOP), and water. Results showed that viable bacterial passed through some filters, many filters were unable to retain visible ink or tobacco smoke particles, and resistance to airflow was increased two-fold or more in many filters when the filters were laden with 10 ml of water. Conflicting data resulted from two different types of DOP testing machines. There was a wide variation in performance among the different brands of filters; variable results also were seen within a given brand. Five brands of filters met the federal DOP standards for HEPA filters, but the wide variation in DOP testing results with two different kinds of DOP machines indicates a need for better standards. The DOP 0.3-micron bubble test is the most readily available nontoxic test to rate filtration efficiency; however, the DOP efficiency rating cannot be used to equate equivalent performance against infectious organisms.

Anesthesiology↗
PubMed1980

Effects of chrysotile asbestos on mononuclear cells in vitro.

Chrysotile asbestos (400 micrograms/ml) was not found to be cytotoxic towards human blood lymphocytes in culture over a 72 h period, although there was indirect evidence of cytoxicity towards plastic adherent mononuclear cells (PAM). There was significant suppression of 3H-thymidine incorporation into cells cultured with phytohaemagglutinin (PHA) in the presence of fibres. It was found even when chrysotile was added 24 h after PHA. No suppression was found for chrysotile-treated PAM-depleted cultures in comparison to control cultures. Antibody-dependent cell-mediated cytotoxicty (ADCC) was inhibited by the presence of chrysotile, and appeared to be due to prevention of contact between antibody-coated target cells and effector cells.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1980

Sequential immunological studies in an asbestos-exposed population. II. Factors affecting lymphocyte function.

As part of an immunological study being carried out on a population exposed to asbestos the effect of two mitogens, phytohaemagglutinin (PHA) and pokeweed mitogen (PWM) on lymphocyte transformation has been assessed on three separate occasions for each mitogen. Both mitogens were assayed using foetal calf (FCS) or autologous serum (AS). Those men with pulmonary fibrosis (as measured by the presence of small opacities on X-ray) had a decrease (P less than 0.05) using PHA (FCS) when compared with those men with normal chest X-rays. Allowance has had to be made for the significant decline with age for both PHA (FCS and AS) transformation. There is a significant increase in PHA (FCS) and PWM (FCS) in ex-smokers and a further increase in smokers. These trends were consistent (at a lower level of significance) from survey to survey. There was no interaction between X-ray category and smoking. The lymphocyte antibody dependent cytotoxic test was measured on four occasions; the only observable effect was a non-significant increase in relation to smoking.

Aging↗
PubMed1979

Bacterial and endotoxin permeability of hemodialysis membranes.

Dialysis fluids containing at least 10(7) bacteria per milliliter and as much as 12,500 ng of endotoxin equivalents per milliliter were dialyzed and ultrafiltered with three types of disposable hemodialyzers. Neither bacteria nor endotoxin, as measured by the Limulus lysate assay, was detected in the sterile compartment despite ultrafiltration. Under these favorable conditions for endotoxin transfer, the maximum transfer rate was calculated to be less than 3.5 ng of endotoxin equivalents per hour. At this rate, it is unlikely that pyrexia during hemodialysis is due to the transfer of endotoxin across an intact dialyzing membrane. Provided that the integrity of the dialyzing membrane is maintained, this investigation indicates that the risk of endotoxemia or bacteremia associated with the use of contaminated dialysis fluids is negligible.

Bacterial Infections↗
PubMed1979

Polyamine metabolism in isoproterenol-stimulated mouse salivary glands.

Isoproterenol (0.3 micronmole/gm body weight) was injected intraperitoneally every 24 h for three days. The synthesis of deoxyribonucleic acid, the concentration of putrescine, spermidine and spermine and the activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase were measured in parotid and submandibular glands at 4 to 8 h after each injection. The parotid glands responded with peaks of DNA synthesis at 24 and 72 h and peaks of putrescine content and decarboxylase activities 8 to 12 h after each injection. Spermidine increased steadily in the parotid, whereas there was little change in the spermine concentration throughout the 72 h. Polyamine metabolism showed much less response in the submandibular gland, and little or no increase in spermidine or spermine levels or in DNA synthesis was observed.

Adenosylmethionine Decarboxylase↗
PubMed1979

Adventitious contamination of intravenous admixtures during sterility testing.

The extent to which contamination of intravenous fluids measured by inhospital sterility-testing may be due to adventitious contamination (i.e., contamination introduced during the sterility-testing procedure) was studied. All one-liter admixtures prepared during a three-day period in a busy centralized i.v. admixture service were studied. Samples of i.v. admixtures were cultured before and after administration by direct ioculation or by culturing the membrane through which the admixture was filtered. Samples of similarly cultured large-volume parenterals served as controls. Contamination rates for control and admixture samples were not significantly different (p = 0.23). Of 10 control and test (admixture) solutions showing contamination before administration, only one test solution again showed contamination after administration but this was with a different microbe. The results suggest that adventitious contamination during sampling/culturing procedures is a component of, and possibly a dominant factor in, the contamination rates detected by inhospital sterility tests. Combined with infection surveillance, sterility tests may be of value when infections are possibly related to admixture contamination.

Bacteria↗
PubMed1978

Effects of polyamines and methylglyoxal bis(guanylhydrazone) on Escherichia coli ribonucleic acid polymerase and the template activity of hepatic cell nuclei in vitro.

Escherichia coli RNA polymerase was assayed with 4 mM Mg2+ and 1 mM Mn2+ using native DNA, heat-denatured DNA, histone-nucleate and isolated rat liver nuclei as the template source. With purified DNA and either or both divalent metal ions, 0.1--5 mM amine stimulated enzyme activity. Spermidine resulted in the greatest stimulation (1.7-fold at 5 mM); whereas, spermine or methylglyoxal bis(guanylhydrazone) first stimulated, then above 3 mM inhibited, the reaction. The addition of unfractionated histone to purified DNA inhibited the reaction by 90%. The subsequent addition of amines resulted in a slight stimulation in incorporation (1.5-fold) in the range of 1--3 mM amine. Alternatively, when enzyme was combined with DNA before histone, only a 20% inhibition was observed and this could be completely prevented by 3 mM spermidine. The addition of amines to isolated nuclei resulted in marked alterations in ultrastructure and Mg2+ content; however, relatively small effects on RNA polymerase activity were observed. With the E. coli enzyme, 0.1--1.0 mM amine stimulated RNA synthesis (1.5-fold) whereas, none of the amines stimulated endogeneous activity in the absence or presence of 300 mM (NH4)2SO4.

Animals↗
PubMed1977

Reservoirs of pseudomonas in an intensive care unit for newborn infants: mechanisms of control.

Potential reservoirs of pseudomonas within a neonatal ICU were evaluated. Colonization of infants by the same pseudomonas pyocin types could be classified as a cluster colonization (occurring over three to ten days), or serial colonization (occurring over longer times). Hands of personnel, sink surfaces, and solutions used to rinse nasopharyngeal catheters were identified as the principle reservoirs. Utilization of a liquid iodophor agent for hand washing and of acetic acid for rinsing suction catheters was associated with a significant reduction in the histologic evidence of sepsis and of pneumonia observed among autopsied infants.

Bacteriological Techniques↗
PubMed1977

Nosocomial outbreak of Candida parapsilosis fungemia related to intravenous infusions.

Candida parapsilosis is rarely isolated from blood cultures. Our hospital surveillance detected an increased rate of isolation of C parapsilosis during a four month period. Fourteen postoperative patients receiving intravenous (IV) hyperalimentation and eight burn patients receiving IV albumin were involved. Hectic fever, the major clinical manifestation, was seen in 61% of cases. Therapy in the postoperative patients consisted merely of discontinuing IV catheters and hyperalimentation, while amphotericin B was needed in five of eight burn patients to control persistent fungemia. Epidemiologic analysis identified a source of the organism in the IV-additive preparation room where C parapsilosis was found contaminating a vacuum system. Organisms apparently refluxed into IV bottles when aliquots were removed to accommodate additives. Of 103 patients who received fluids prepared with the contaminated system, 21% became infected with C parapsilosis. Infection surveillance was instrumental in detection and control of the outbreak. Routine guideline should be established to insure the sterility of IV fluids containing additives.

Adult↗
PubMed1976

The interaction between vitamin B-12 and micelles in aqueous solution.

The apparent pK for benzimidazole displacement of a number of cobalamins is markedly affected by the presence of sodium lauryl sulfate micelles. However, micelles of cetyltrimethylammonium bromide or Triton X have little or no effect on the pK. By measuring the apparent pK as a function of sodium lauryl sulfate concentration, the association constants between the micelles and both base on and base off methylcobalamin were calculated. This calculation indicates that the base off form is strongly associated with the micelle while the base on form is not.

Binding Sites↗
PubMed1975

Effects of polyamines and methylglyoxal bis(guanylhydrazone) on hepatic nuclear structure and deoxyribonucleic acid template activity.

1. The interaction of polyamines and methylglyoxal bis(guanythydrazone) (1, 1'-[(methylethanediylidene)-dinitrilo]diguanidine) with isolated rat liver nuclei was investigated by electron microscopy. 2. At 4mM, putrescine was without effect; however, spermidine, spermine or methylglyoxal bis(guanythydrazone) resulted in dispersed chromatin and alterations in nucleolar structure. In addition, spermidine or methylglyoxal bis(guanylhydrazone) caused marked aggregation of interchromatin granules. 3. The DNA template property of calf thymus DNA was examined by using DNA polymerases from Escherichia coli, Micrococcus lysodeikticus and calf thymus in the presence of 0-5 mM-amine. 4. In the presence of DNA polymerase, spermine or methylglyoxal bis(guanylhydrazone) inhibited activity, whereas putrescine or spermidine had much less effect or in some cases stimulated [3H]dTMP incorporation. 5. Template activity which was inhibited by spermine or methylglyoxal bis(guanylhydrazone) could be partially restored by additional DNA or enzyme. 6. When mixed with calf thymus DNA, calf thymus histone inhibited template activity as measured with E. coli DNA polymerase. The template activity of such a 'histone-nucleate' could not be restored by putrescine, spermidine, spermine or methylglyoxal bis(guanylhydrazone). 7. DNA template activity of isolated rat liver nuclei was tested by using E. coli DNA polymerase. None of the amines was able to increase the template activity of the nuclear DNA in vitro.

Animals↗