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Biomedical subjects

B D Jones

Publications and source records attributed to B D Jones.

At least 91 records · Page 5Linked to original sources
PubMed1987

Genetic and biochemical diversity of ureases of Proteus, Providencia, and Morganella species isolated from urinary tract infection.

Bacterial urease, particularly from Proteus mirabilis, has been implicated as a contributing factor in the formation of urinary and kidney stones, obstruction of urinary catheters, and pyelonephritis. Weekly urine specimens (n = 1,135) from 32 patients, residing at two chronic-care facilities, with urinary catheters in place for greater than or equal to 30 days yielded 5,088 phenotypically and serotypically diverse bacterial isolates at greater than or equal to 10(5) CFU/ml. A total of 86% of specimens contained at least one urease-positive species, and 46% of 3,939 gram-negative bacilli were urease positive. For investigation of genetic relatedness of urease determinants, whole-cell DNA from 50 urease-positive isolates each of Providencia stuartii, Providencia rettgeri, P. mirabilis, Proteus vulgaris, and Morganella morganii were hybridized with a urease gene probe derived from within the urease operon of Providencia stuartii BE2467. The percentage of strains hybridizing with the gene probe was 98 for Providencia stuartii, 100 for Providencia rettgeri, 70 for P. mirabilis, 2 for M. morganii, and 0 for P. vulgaris. Electrophoretic mobilities of ureases from representative isolates revealed nine different patterns among the five species. The urease gene probe hybridized with fragments of HindIII-digested chromosomal DNA from all isolates except M. morganii. Fragment sizes differed between species. Molecular sizes of the enzymes, determined by Sephacryl S-300 chromatography, were found to be 280 kilodaltons (kDa) (P. mirabilis), 323 to 337 kDa (Providencia stuartii, Providencia rettgeri, P. mirabilis, P. vulgaris), 620 kDa (providencia rettgeri), and greater than 700 kDa (M. morganii, Providencia rettgeri). Kms ranged from 0.7 mM urea for M. morganii to 60 mM urea for a P. mirabilis isolate. In general, P. mirabilis ureases demonstrated lower affinities for substrate but hydrolyzed urea at rates 6- to 25-fold faster than did enzymes from other species, which may explain the frequent association of this species with stone formation.

Aged↗
PubMed1987

Urease activity of Proteus penneri.

Ten strains of Proteus penneri isolated from geographically diverse laboratories were tested for urease activity. Cell lysates from urea-induced cells had a mean activity of 4.9 +/- 4.1 mumol of NH3 per min per mg of protein. On nondenaturing 6% polyacrylamide activity gels, the enzymes of P. penneri had very similar electrophoretic mobilities within species and within the Proteus genus but were distinct from the ureases of Providencia and Morganella species. On lower-percentage polyacrylamide, differences in mobilities of the ureases could be detected between the Proteus species. From representative strains, the P. penneri urease was found to be inducible by growth in urea and had an apparent molecular weight of 246,000 +/- 9,000, an isoelectric point of 5.1, and a Km for urea of 14 mM and was inhibitable by acetohydroxamic acid, hydroxyurea, and EDTA. In an in vitro model of struvite formation, a P. penneri strain produced abundant crystals on a glass rod submerged in synthetic urine in the absence but not presence of acetohydroxamic acid (500 micrograms/ml).

Chromatography, Gel↗
PubMed1987

Transient mood elevation associated with antidepressant drug decrease.

The development of hypomania, mania and transient mood elevation within 2-3 days of antidepressant discontinuation, and lasting days to several weeks has been reported in unipolar depressed patients. Imipramine and desipramine are the antidepressants most frequently associated with the above phenomena. A reported case of transient mood elevation following abrupt reduction but not discontinuation of desipramine therapy in a woman with unipolar depression is described. The phenomenon was observed and documented on two separate occasions. Mood elevation occurred despite decreased plasma levels of the drug. Relapse followed despite maintenance of dose and similar drug plasma levels. Factors which could account for the transitory improvement of mood are examined. It is suggested that the patient's improvement in mood may have occurred due to a rebound paradoxical therapeutic effect. The features of the presented case history which appear to support this hypothesis are discussed. Also the clinical implications of this phenomenon are reviewed.

Bipolar Disorder↗
PubMed1986

Cloning of urease gene sequences from Providencia stuartii.

Providencia stuartii was the most prevalent isolate recovered from urine specimens taken weekly over a 1-year period from 51 nursing home patients with urinary catheters in place. Thirty percent of the isolates were urease positive. Urease, which is implicated in renal stone formation, was shown to be transmissible on an 82-kilobase conjugative plasmid in one isolate. Plasmid DNA isolated from this strain was digested with EcoRI, ligated into the EcoRI site of pBR322, and used to transform Escherichia coli HB101. Ampicillin-resistant clones were replica plated onto urea segregation agar, and a urease-positive clone, designated pMID101, was isolated. Recombinant and native urease from cell lysates had identical electrophoretic mobilities on nondenaturing polyacrylamide urease activity gels. The native enzyme was induced fourfold when cells were grown in the presence of 0.1% urea and had a km of 9.4 mM and a Vmax of 3.2 mumol of NH3 per min per mg of protein. Its molecular weight was estimated to be 375,000 +/- 35,000 by Sephacryl S-300 chromatography. The enzyme was cytoplasmic in P. stuartii, was inhibited in vitro by hydroxyurea, acetohydroxamic acid, and EDTA, and appears to have a complex subunit structure and a unique molecular size within genera of the Proteeae tribe.

Cell Compartmentation↗
PubMed1986

Chronic central anticholinergic toxicity in manic depressive illness mimicking dementia.

Acute anticholinergic delirium has been reported to occur following ingestion of antidepressants, neuroleptics and antiparkinsonian drugs in toxic and therapeutic doses. A case is described of a chronic central anticholinergic syndrome in a patient receiving a combination of such drugs. This chronic anticholinergic toxicity was superimposed on manic depressive illness which resulted in incorrect diagnoses including schizophrenia and dementia and, accordingly, improper management. Diagnosis of central anticholinergic toxicity may be overlooked in psychiatric patients because the symptoms of toxicity can be incorrectly ascribed to psychiatric illness. It may also be overlooked in elderly patients who are prone to demonstrate confusion and problems with memory. The recognition of this syndrome in the patient reported, at least nine years after it developed, led to appropriate management which ultimately resulted in a dramatic change in her ability to function.

Aged↗
PubMed1986

Effects of storage temperature and time on canine plasma ammonia concentrations.

Stability of ammonia in canine plasma was determined, with regard to temperature and time of storage. Heparinized venous blood samples were collected from 8 healthy dogs, immediately placed in an ice water bath, and centrifuged at 5 C. Plasma was harvested from the blood samples, and the initial analysis of each sample for plasma ammonia was performed within 30 minutes after collection. Separate aliquots of the plasma from each dog were stored at 21 C, 4 C, -15 C, or -40 C. Ammonia concentrations of the aliquots stored at the various temperatures were determined at 24, 48, and 96 hours after collection. Statistical analysis of the data from each dog did not indicate a significant relationship between the initial concentration of plasma ammonia and subsequent determinations. Correlation or significance was not found among samples stored at similar temperatures and evaluated at similar times.

Ammonia↗
PubMed1985

Hepatic biopsy.

Hepatic biopsy plays an integral part in the formation of the diagnosis, selection of the therapy, and determination of the prognosis in clinical cases of hepatic disease. It has been shown that results of hepatic biopsy correlate well with postmortem findings and findings of liver function tests. Hepatic biopsy is not difficult to perform and the benefits usually outweigh the risks and costs. The techniques described have many variations that are influenced by the experience and skill of the practitioner and the equipment available to the practitioner. It is the authors' opinion that, with the proper training, every practitioner can obtain hepatic biopsies and, thus, increase the quality of medical care to their patients.

Animals↗
PubMed1985

Tardive dysmentia : further comments.

The author distinguishes between the putative neuroleptic-induced disorders of tardive dysmentia and supersensitivity psychosis. The distinction is made with regard to clinical features, response to pharmacological intervention, and proposed etiologies. It is suggested that tardive dysmentia is due not to dopaminergic supersensitivity but to some other neurotoxic phenomenon associated with the use of neuroleptic drugs. The possibility that cholinergic mechanisms are involved in the tardive dysmentia syndrome is examined. Finally, the potential for such drug-induced disorders to confuse diagnosis is highlighted.

Antipsychotic Agents↗
PubMed1984

Withdrawal symptoms after long-term treatment with low-potency neuroleptics.

Twenty-six chronic schizophrenic outpatients receiving low-potency anticholinergic neuroleptics were switched over periods of up to 2 years to an equivalent dose of high-potency neuroleptics. Of these patients, 85% experienced withdrawal symptoms, mainly insomnia, anxiety, and tensional restlessness. Complete withdrawal of low-potency medication was achieved during the study period in 9 patients only. The mean duration of treatment with low-potency neuroleptics was 15 years and the mean dose was 147 mg chlorpromazine equivalents/day. It is suggested that new symptoms associated with withdrawal of low-potency neuroleptics may lead to overcompliance by patients and difficulty in achieving the minimum therapeutic dosage. Thus, low-potency neuroleptics would not appear suitable for the long-term treatment of most schizophrenic patients.

Adult↗
PubMed1982

Normal ventricles in young schizophrenics.

The CT scans of 11 schizophrenics and 26 controls were evaluated for both linear (Evan's and cella media ratios) and volume (planimetry and grid ratios) measurements of ventricular size. There were no differences between the two groups on any of the measures obtained. These results are discussed in relation to previous reports showing ventricular enlargement in schizophrenics. The relatively younger age and briefer period of hospitalization in this present sample are suggested as variables possibly associated with these findings.

Adult↗