Dynamic attending and responses to time.
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Attention↗
Biomedical subjects
M R Jones
Publications and source records attributed to M R Jones.
Plasma amino acid concentrations in premature infants: effect of sampling site.
Amino acid concentrations in plasma obtained from infants by heel puncture differ from those in venous plasma primarily because of skin contamination but data from the two sites might agree more closely in premature infants because of their poorly developed sweat glands. To evaluate the importance of sampling site, amino acids were analyzed by a sensitive high-performance liquid chromatographic method in plasma obtained both by heel puncture and venipuncture in 14 premature infants. Histidine, tryptophan, alanine, aspartic acid, glycine, and serine were higher in capillary plasma. Tryptophan and glycine levels in capillary plasma correlated strongly with those in venous plasma. An additional wash with soap and water done in five infants did not eradicate the differences. Thus the lack of agreement between data from the two sites may be due to factors other than contamination.
Alanine↗
Uncoupler resistance in Escherichia coli: the role of cellular respiration.
Bioenergetic properties of a mutant strain of Escherichia coli K12 designated TUV, which is resistant to the protonophoric uncoupling agent 4,5,6,7-tetrachloro-2-trifluoromethylbenzimidiazole (TTFB) have been compared with those of its non-resistant parent, E. coli K12 Doc-S. Strain TUV grew and respired some 20-30% faster than strain Doc-S, and was cross-resistant to carbonylcyanide p-(trifluoromethoxy)phenylhydrazone and triphenyltin, but not to 2,4-dinitrophenol. Phosphorus nuclear magnetic resonance demonstrated the TTFB-mediated collapse of the transmembrane pH gradient at identical rates in starved cells of both strains, indicating that uncoupler access and function were unimpaired in the mutant under these conditions. Strain TUV displayed enhanced uncoupler resistance and maintained intracellular pH and ATP levels only when respiring. On the other hand, strain TUV also showed increased resistance to novobiocin, implying that its outer wall permeability had been lowered. We suggest that the active resistance of strain TUV results from the exclusion of uncoupler by the interaction of inner and outer membrane components in a manner modulated by the degree of cellular energization.
Adenosine Triphosphate↗
Rhodococcus equi: an emerging opportunistic pathogen?
Human infection with Rhodococcus equi is apparently rare with most published reports describing the development of lung abscesses in immunocompromised hosts. Of only 18 cases of infection previously recorded, four have recently occurred in patients with the acquired immune deficiency syndrome (AIDS). In Australasia, R. equi has frequently been isolated from soil and infected farm animals yet no human infections have been reported thus far. Three cases of R. equi infection have occurred in New Zealand and, collectively, they cover a wider spectrum of disease than that previously recognised. The natural history of R. equi infections, their clinical features and treatment are described in the light of our recent experience.
Acquired Immunodeficiency Syndrome↗
The pathogenesis and clinical significance of cytologically detectable oral Candida in acute leukemia.
Using serial examination and oral cytology, 50 adult patients undergoing induction therapy for acute leukemia were studied for oral colonization with candida species. Ninety percent of patients were found to be colonized with Candida, with most of these colonizations present by day 14. The 30 patients exhibiting colonization with pseudohyphae received ketoconazole 400 mg daily by mouth. Of 20 patients in this group treated for 5 or more days, Candida organisms were eradicated in nine. Sixteen patients from the above group with persistent colonization on ketoconazole were treated by independent clinical decision for sustained fever and neutropenia with Amphotericin B, but only one responded by elimination of colonization. Seven of the 15 patients who did not initially receive ketoconazole developed Candida dissemination in contrast to two of 30 who received ketoconazole initially (P = 0.003, Fisher's exact test). No patient who initially had or acquired a negative cytology developed oral or disseminated candidiasis. Clinical oral candidiasis occurred in three patients, all of whom were receiving amphotericin B. Approximately 90% of these patients have or develop oral colonization with Candida organisms as identified by oral cytology. Those with colonization, both with and without pseudohyphae present, are at risk for dissemination. Amphotericin B does not eliminate colonization remaining after treatment with 400 mg of ketoconazole daily. More effective diagnostic and therapeutic strategies are needed to identify and eliminate Candida organisms and to prevent disseminated candidiasis in this population of patients.
Acute Disease↗
Management of Pneumocystis carinii pneumonia in the immunocompromised host.
From 1982 to 1987, 22 patients with proven Pneumocystis carinii pneumonia were diagnosed at Wellington Hospital. Patients comprised 15 males and 7 females aged 15-76 years and included seven with AIDS, eight with haematological malignancy and seven with renal disease. Two distinct clinical prodromes occurred. In renal patients a classic fulminating pneumonitis developed over 24 to 72 hours. In patients with AIDS a more indolent illness occurred lasting 3 or more weeks and was characterised by fever, dry cough and breathlessness. Haematology patients showed no specific duration of prodrome. At the time of diagnosis all had an abnormal chest radiograph and the arterial PO2 was reduced in all but one case. An invasive diagnostic procedure was performed in all except one case where the diagnosis was made at post mortem. Two patients required a second procedure to establish the diagnosis. Procedures performed included bronchoalveolar lavage [14], open lung biopsy [7] and transbronchial lung biopsy [2]. All patients were treated with high dose cotrimoxazole and 18 survived to leave hospital. A review of the approach to the diagnosis and treatment of Pneumocystis carinii pneumonia is presented.
Acquired Immunodeficiency Syndrome↗
Tests of parallel versus integrated structure in polyrhythmic tapping.
Musically trained subjects tapped three beats with their right hand versus two beats with their left hand in synchrony with two corresponding tones. For independent groups of subjects, the pitch difference of the two tones was either small to encourage an integrated perceptual organization or large to encourage a streamed perceptual organization. Integrated versus parallel motor organization was tested by examining the pattern of covariances among intertap intervals. All subjects exhibited integrated motor organization. An integrated multiplicative hierarchical model of motor organization was superior to a serial chained model and to an independent hierarchical model in describing the pattern of covariances. The subjects who heard tones that encouraged an integrated percept performed with less variability than the subjects who heard tones that encouraged a streamed percept. This superior performance with an integrated motor organization and an integrated rather than a streamed perceptual organization is interpreted as evidence for temporal perceptual-motor compatibility.
Journal Article↗
Effect of marginal calcium intake on blood pressure in the Wistar rat.
Epidemiological studies in man suggest that blood pressures tend to be higher in persons with low calcium (Ca) intakes. Previous studies in normal rats have shown that severe Ca restriction raises blood pressure. The chronic effect of moderate Ca restriction is not known. We evaluated the effect upon systolic blood pressure of rearing young Wistar rats on a diet marginally adequate in Ca. Male weanling Wistar rats (8 rats per group) were placed on one of four diets containing 0.5% Ca (control diet), 0.4% Ca, 0.3% Ca, or 0.2% Ca. The three experimental diets were made up by replacing CaHPO4 in the salt mix with (NH4)H2PO4. Content of PO4 and electrolytes other than Ca was the same for all 4 diets. Sodium (Na) content was 0.1%. Diets were fed for 19 weeks. Rats did not grow normally on the 0.2% Ca diet, but growth was normal on the other three diets. There was no overall statistically significant effect of diet upon systolic pressure. During the first nine weeks of study there were no significant differences between groups and no consistent trends. During the last seven weeks, however, there was a consistent trend toward higher systolic pressures as Ca intake decreased. The mean change in blood pressure during the last five weeks of study from the baseline value at 4 weeks of age was significantly greater in rats consuming 0.2% Ca and tended to be greater in rats consuming 0.3 and 0.4% Ca than in controls. On several occasions, group mean systolic pressures were significantly greater in rats on the experimental diets than in controls. Systolic pressures for individual rats, averaged over the last seven blood pressure measurements, varied over a wider range in the experimental groups than in rats eating the control diet, and the distribution in the experimental groups was shifted toward higher systolic pressures. The results suggest that rearing normal rats on a diet marginally adequate in Ca may lead to a modest elevation in the blood pressures of some, but not all rats. The effect, however, is of much smaller magnitude than that observed with severe Ca restriction.
Aging↗
Mineral balance and blood pressure in the young spontaneously hypertensive rat.
To evaluate factors that might be related to the pathogenesis of hypertension in spontaneously hypertensive rats (SHR), mineral balance studies were conducted in SHR and control Wistar-Kyoto (WKY) rats at the ages of 9, 13 and 16 wk. During the first balance period, before onset of hypertension, Na, Ca, Mg and P balances were all significantly more positive in SHR than in WKY rats. Percentage of absorbed Na excreted in urine was correlated with the rise in blood pressure of SHR but not of WKY rats during the first 4 wk of the study. At 13 wk balances of all four nutrients still tended to be higher in SHR. During the 16th wk of life, after onset of hypertension, Na, Ca and P balances were similar in SHR and WKY rats, but Mg balance was significantly lower in SHR. The percent urinary excretion of absorbed Na was lower in SHR at 9 wk of age, but after onset of hypertension it was similar to that in WKY rats. Food intake was always greater in SHR, whereas growth during the study was less, and absorption of Ca, Mg and P declined more rapidly with age in SHR than in WKY rats. The data suggest that nutrient malabsorption in SHR, if it occurs at all, is most likely an effect of, rather than a cause of, hypertension.
Absorption↗
Free amino acid pools in the spontaneously hypertensive rat: a longitudinal study.
To investigate abnormalities of metabolism in spontaneously hypertensive rats (SHR) that might be related to the pathogenesis of hypertension, we measured concentrations of free amino acids in plasma and in homogenates of skeletal muscle from SHR and age-matched normotensive Wistar-Kyoto (WKY) rats. These pools were evaluated in rats aged 3.5, 6, 8 and 28 wk, corresponding to time points before, during and after onset of hypertension. Amino acid content of aortic tissue also was examined at 3.5 and 6 wk. In plasma, amino acid concentrations were relatively unchanged throughout the study. Free amino acid content of muscle, on the other hand, decreased markedly with age in both strains. The most consistent and quantitatively important difference between strains was the much smaller muscle pool of lysine in SHR at 3.5, 6 and 8 wk of age compared with WKY controls. The arginine pool was also smaller in SHR but only at 3.5 and 6 wk. Other urea cycle amino acids were also lower in muscle of SHR at 3.5 wk. These alterations in the muscle amino acid pool were mirrored in plasma and were also found in aortic tissue. Glutamine was higher in muscle and plasma of SHR at 6 wk and thereafter. At 28 wk, however, many amino acids, including the branched-chain amino acids and tyrosine and glutamine, were present at higher concentrations in muscle and plasma of SHR than in those of WKY rats. These differences, because they occur most strikingly in SHR during the prehypertensive state, may be related to the development of hypertension.
Amino Acids↗
Outbreak of methicillin-resistant Staphylococcus aureus infection in a New Zealand hospital.
During a 17 month period from March 1985 to July 1986, 30 patients and four members of staff became infected or colonised with a single strain of methicillin-resistant Staphylococcus aureus (MRSA) during an outbreak which originated at Wellington Hospital. Initially, crossinfection occurred within the intensive care unit but infected or colonised patients became distributed to 14 hospital wards and to five other hospitals within New Zealand. MRSA septicaemia contributed to the death of two patients. The source of the epidemic strain of MRSA has not been established with certainty, but may have been introduced by a staff nurse known to be a carrier when employed at an Australian hospital. The investigation, management and eventual control of this first outbreak in New Zealand are described.
Adolescent↗
A study of experimental endocarditis in pigs.
In a proposed study of fibrinolytic therapy in experimental streptococcal endocarditis, this disease was induced in pigs by preinoculation damage to the aortic valve; the technique of this is described. If untreated, the disease runs a protracted course, similar to that in man. Fibrinolytic activity, normally low in the pig, can be increased by stress, by urokinase, by plasmin and briefly by streptokinase if supplemented by human plasminogen. The proposed experiments were abandoned in pigs, chiefly because of technical difficulties in obtaining frequent samples of blood and maintaining infusions. In experiments on the response of ADP-induced aggregation of pig platelets to prostacyclin, they were found to be about 10 times more resistant than human platelets. It is suggested that this resistance to prostacyclin, together with their usually low state of systemic fibrinolytic activity, may explain the susceptibility of pigs to bacterial endocarditis.
Adenosine Diphosphate↗
Escherichia coli mutants resistant to uncouplers of oxidative phosphorylation.
Two mutant strains of Escherichia coli K 12 Doc-S resistant to the uncoupling agents 4,5,6,7-tetrachloro-2-trifluoromethyl benzimidazole and carbonyl cyanide m-chlorophenylhydrazone were isolated. These strains, designated TUV and CUV, were capable of (a) growth, (b) the transport of succinate and L-proline and (c) electron-transport-linked oxidative synthesis of ATP in the presence of titres of uncoupler which inhibited these processes in strain Doc-S. The inhibition of transport of L-proline by a fixed titre of uncoupler was sharply pH dependent in strain Doc-S: uptake was unaffected at pH 7.6 but completely inhibited at pH 5.6. This pH dependence was not shown by the resistant strains. We believe that uncouplers were equally accessible to their site(s) of action in the energy-conserving membrane of the sensitive and resistant strains. We conclude that uncoupler resistance in these strains of E. coli has arisen as a consequence of mutations which directly affect a specific site of uncoupler action within the cytoplasmic membrane, rather than as a consequence of a decrease in the permeability of cells to uncoupler.
Benzimidazoles↗
Candida albicans vertebral osteomyelitis in chronic renal failure.
Invasive candidal infections are encountered with increasing frequency in compromised hosts but bone infection is uncommon. A woman with systemic lupus erythematosus and end-stage renal failure managed by continuous ambulatory peritoneal dialysis developed a painful thoracic kyphosis and a lytic lesion in the vertebral bodies of T10 and T11. Blood cultures were sterile but bone biopsy material contained Candida albicans which also grew on culture. Circulating immune complexes were measured in high levels and contained candida antigens and specific anti-candida antibody as determined by isoelectric focusing, immunoblotting and immunoprinting techniques. Pain persisted after anti-fungal therapy had sterilized the lesion necessitating surgical excision of affected vertebrae, kyphosis correction and iliac crest bone grafting. The titres of circulating immune complexes and anti-candidal precipitins closely paralleled the clinical course.
Adult↗
Dynamic pattern structure in music: recent theory and research.
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Communication↗
Fibrinolytic therapy in bacterial endocarditis: experimental studies in dogs.
An investigation was undertaken to assess the value of adding streptokinase therapy to standard penicillin treatment of artificially induced infective endocarditis due to Streptococcus sanguis. In pigs a low-grade infection could be induced which closely simulated streptococcal endocarditis in man, but for technical reasons this model proved unsatisfactory for further experimentation. In dogs the induction of S. sanguis endocarditis produced a more severe illness with a short natural history. Dogs were divided into two groups, one treated with penicillin alone, the other with penicillin and streptokinase. A five-day course, in which twice daily injections of an acylated streptokinase-plasminogen complex were given, caused a substantial reduction in the size of vegetations and possibly a higher proportion of cures and less damage to the valves. Infarction of the brain, almost certainly due to embolism, was significantly greater in the streptokinase treated group, but the same was not true of the kidneys. The possible value of such treatment for certain kinds of bacterial endocarditis in man, especially in the right side of the heart, is discussed.
Animals↗
Treatment of Staphylococcus aureus endocarditis: an analysis based on 25 proven cases.
Twenty-five consecutive unequivocal cases of Staphylococcus aureus endocarditis in a single centre over 5 years were reviewed. Despite an unusually high proportion of prosthetic infections an early mortality of only 16% was observed. Analysis reveals that early diagnosis and prompt effective antibiotic chemotherapy were important factors in achieving this low mortality. Monotherapy with an isoxazolyl penicillin (flucloxacillin) was shown to be as effective as combination therapies, and there was a significant association between the use of aminoglycosides and subsequent renal damage.
Adolescent↗
Multihormonal islet cell carcinoma in a greater bushbaby (Galago crassicaudatus argentatus).
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Adenoma, Islet Cell↗