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Biomedical subjects

R James

Publications and source records attributed to R James.

At least 253 records · Page 14Linked to original sources
PubMed1984

Effects of respirators under heat/work conditions.

Physiological responses and perceived strain of five unacclimatized male subjects were studied. The subjects were exposed to heat during an exercise task and were evaluated while wearing half and full facepiece, cartridge-type, air-purifying respirators, and without a respirator. The exercise consisted of walking on a treadmill for a period of 1 hour in a controlled environmental chamber at each of two different energy expenditure levels (200 and 400 Kcal/hr) (approximately equal to 58 and 116 Watts) and two different heat exposures (air temperatures of 25 degrees C and 43.3 degrees C). The results indicated that wearing a full facepiece respirator imposed significant physiological strain added to that caused by the heat and workloads used in the study. Five of the six physiological measures show this increased physiological strain: heart rate; minute ventilation; oxygen consumption; energy expenditure; and oral temperature. There was no detectable effect on sweat rate. Although subjective ratings indicated more discomfort with increasing physiological strain, the observed correlations between such measures were low (Tb less than .60). The net consequence of the significant effects indicates that workers' tolerance to moderate or higher levels of work under hot conditions while wearing a respirator is reduced. The reduction is more pronounced when wearing a full mask than when wearing a half mask. Changes in respirator design which minimize respiratory dead space are suggested to alleviate this problem. Otherwise, prevention of excessive physiological strain from respirator use when working at moderate or higher levels at hot job sites could necessitate more rest breaks or limiting work time under such conditions.

Adult↗
PubMed1984

Two new E colicins, E8 and E9, produced by a strain of Escherichia coli.

We have isolated a strain of Escherichia coli from chicken caeca which produces two E colicins and colicin M. This strain has seven plasmids, five of which have been transferred to E. coli K12. Two E. coli K12 derivatives which produce the two E colicins separately have been tested against seven standard E colicin producing strains which define seven different immunity groups. Our results indicate that these new E colicins define two further immunity groups, E8 and E9.

Animals↗
PubMed1984

Localization and characterization of a gene on the ColE3-CA38 plasmid that confers immunity to colicin E8.

Escherichia coli W3110 cells carrying the ColE3-CA38 plasmid are immune to externally added colicin E8, a newly described member of the E group colicins. By molecular cloning and transposon mutagenesis we localized the colicin E8 immunity gene between the EcoRI site (4.0 kb on the restriction map) and the PvuII site (3.68 kb) of the ColE3-CA38 plasmid. This placed the colicin E8 immunity gene between the colicin E3 immunity gene and lys, the region which determined mitomycin C sensitivity. Insertion of a transposon into the colicin E3 structural gene prevented the synthesis of active colicin and completely abolished mitomycin C sensitivity, but had no effect on the two immunity genes. In contrast, insertion of a transposon into the colicin E8 immunity gene had no effect upon colicin E3 production or colicin E3 immunity but did abolish mitomycin C sensitivity. The phenotype conferred by plasmids with a transposon inserted into the lys region of ColE3-CA38 was dependent upon the site of insertion.

Chromosome Mapping↗
PubMed1983

Relative substrate affinity index values: a method for identification of beta-lactamase enzymes and prediction of successful beta-lactam therapy.

Using a nitrocefin competition assay, I determined the relative substrate affinity index (RSAI) values of nine clinically significant beta-lactamase enzymes against a range of beta-lactams. Using selected beta-lactam substrates, I observed large differences in the RSAI values of the nine enzymes that were sufficient in many cases to positively identify specific enzymes. I made use of the unique RSAI values of SHV-1, TEM-1, and TEM-2 beta lactamases with cefoxitin to screen for the presence of these enzymes in Klebsiella aerogenes clinical isolates. The RSAI values also allow for the prediction of the outcome of beta-lactam therapy against specific beta-lactamase-producing isolates.

Anti-Bacterial Agents↗
PubMed1983

Who goes to a natural therapist? Why?

This survey investigated the understanding and attitudes of 38 patients using alternative therapies and their reasons for doing so. Although the small sample could bias the results, the article opens the subject for discussion and could serve as a model for a larger survey from which more valid conclusions could be drawn.

Acupuncture Therapy↗
PubMed1983

'Doctor I can't sleep at night'.

Insomnia is a common problem in medical practice. When the patient says 'Doctor I can't sleep at night' the cause should be identified from stress, psychological disturbance, physical symptoms, disease, drugs or environmental or idiopathic factors. A behavioural strategy focusing on relaxation and methods for stimulus control is presented.

Combined Modality Therapy↗
PubMed1982

Analysis of hydroxylated and demethylated metabolites of mephenytoin in man and laboratory animals using gas-liquid chromatography and high-performance liquid chromatography.

Separation of urinary mephenytoin metabolites was evaluated under various gas-liquid chromatographic (GLC) and high-performance liquid chromatographic (HPLC) conditions. A simple and rapid alkylation procedure is described for GLC-using a nitrogen sensitive thermionic detector. The in situ formation of sodium methinylsulfinylmethide is used as base for the perpropylation of hydantoins and their metabolites. Normal-and reversed-phase HPLC of the underivatized compounds was performed using four different types of stationary phases. None of the GLC systems separated all the six hydantoin compounds tested, whereas, normal-and reversed-phase HPLC were able to obtain a complete separation of these compounds. The major metabolites of mephenytoin were 5-phenyl-5-ethylhydantoin, 3-methyl-5-(4-hydroxyphenyl)-5-ethylhydantoin and 5-(4-hydroxyphenyl)-5-ethylhydantoin in man, rat, mouse, rabbit, and guinea pig. 3-Methyl-5-phenyl-5-(2-hydroxyethyl)-hydantoin and 3-methyl-5-(3-hydroxyphenyl)-5-ethylhydantoin are major metabolites in the dog.

Animals↗
PubMed1981

The differential localization of various drug metabolizing systems within the rat liver lobule as determined by the hepatotoxins allyl alcohol, carbon tetrachloride and bromobenzene.

Rats were pretreated with allyl alcohol, carbon tetrachloride or bromobenzene to induce histopathological evidence of periportal, midzonal to centrilobular, and centrilobular hepatic necrosis. The amount of various drug metabolizing enzyme systems present after necrosis was determined indirectly by measuring the rate of metabolism for specific substrates in vitro. The chemically induced hepatocellular injury of these toxins produced variable but significant alterations in hepatic drug metabolism. The changes in enzymatic activity related well with the area of the lesion produced by each toxin. Thus, these hepatotoxins appear to be useful as probes to determine the hepatolobular distribution of the various drug metabolizing enzyme systems studied. Aniline hydroxylase and p-nitroanisole o-demethylase were concentrated in the midzonal and periportal zones, while aminopyrine N-demethylase was more uniformly distributed along the cytochrome P-450 gradient. Glucuronyltransferase was more heavily concentrated in the periportal-midzonal area, acetyltransferase was centrilobular-midzonal and glutathionetransferase was concentrated in the midzonal region. Thus, as is the case for cytochrome P-450, there appears to be a high degree of regional organization for all of the drug metabolizing enzymes within the hepatic lobule.

1-Propanol↗
PubMed1980

Anatrophic nephrolithotomy for removal of staghorn or branched renal calculi.

Forty anatrophic nephrolithotomies were performed in 38 patients between November, 1965, and December, 1977, to remove staghorn or branched renal calculi. Thirty-six (95 per cent) of the patients' preoperative urine cultures were infected, and postoperatively 35 of the cultures (88 per cent) were sterile. Magnesium ammonium phosphate calculi were present in the majority of patients (67 per cent). In 6 patients (15 per cent) transient nephrocutaneous fistulas developed. Thirty-six of the 40 renal units (90 per cent) had improved or stable intravenous pyelograms postoperatively. The patients had been followed for an average of twenty months (four to one hundred and twelve months). In 6 patients (15 per cent) recurrent renal calculi developed, and 3 patients (8 per cent) had residual calculi during this period.

Adult↗
PubMed1980

Synthesis, biological evaluation, and preliminary structure-activity considerations of a series of alkylphenols as intravenous anesthetic agents.

Following our discovery of the intravenous (iv) anesthetic activity of 2,6-diethylphenol in mice, a series of alkylphenols was examined in this species and the most active analogues were further evaluated in rabbits. The synthesis of compounds which were not commercially available was accomplished by adaptations of standard ortho-alkylation procedures for phenols. Structure-activity relationships were found to be complex, but, in general, potency and kinetics appeared to be a function of both the lipophilic character and the degree of steric hindrance exerted by ortho substituents. The most interesting compounds were found in the 2,6-dialkyl series, and the greatest potency was associated with 2,6-di-sec-alkyl substitution. In particular, 2,6-diisopropylphenol (ICI 35 868) emerged as a candidate for further development and has subsequently been shown to be an effective iv anesthetic agent in man.

Anesthesia, Intravenous↗