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Biomedical subjects

J Jones

Publications and source records attributed to J Jones.

At least 469 records · Page 26Linked to original sources
PubMed1993

Does labour substitution occur in district general hospitals?

A survey of 31 district general hospitals found a large variation in hours of medical and nursing time available per inpatient episode in general medicine and its associated specialties. These differences could not be attributed to case-mix variation or severity. The application of weightings to different grades of nursing and medical staff had little effect on either the rankings of hospitals by staff hours per episode, or the overall degree of variation in staffing levels. The results show no evidence to suggest that hospitals with relatively low levels for one category of staff are compensated by relatively high levels of another. It would appear that those hospitals with high levels for one category of staff are also well provided for the others. This evidence of inequality may reflect historic patterns of resource allocation that recent manpower policies might seek to redress. Studies of the relationship between staffing levels and quality of patient care should be undertaken before adopting a policy of labour redistribution.

Data Collection↗
PubMed1993

Risk and outcome of aspiration pneumonia in a city hospital.

Because aspiration pneumonia contributes significantly to morbidity and mortality in hospitalized patients, this study was undertaken to identify risk factors for morbidity and mortality associated with aspiration pneumonia. Patients with a discharge diagnosis of aspiration pneumonia in 1985 and 1990 were studied. Factors associated with death from aspiration pneumonia were: altered mental status, cerebrovascular accident, endotracheal intubation, tachycardia, and hypoxemia. Fever, cough, and unilateral infiltrates on chest radiograph were associated with survival. Attention to proper positioning of comatose patients, aggressive treatment of gastroesophageal reflux, and strict attention to endotracheal tubes and tracheostomies should decrease the morbidity and mortality associated with aspiration pneumonia.

Adult↗
PubMed1992

Escherichia coli genes involved in cell survival during dormancy: role of oxidative stress.

When Escherichia coli cells reach stationary phase of growth, specific gene products are synthesized that protect cells while dormant. "Aged" cells may remain viable in cultures for years. For example, agar cultures stored for 38 years still had more than 10(5) viable cells/ml. However, when specific mutants were cultured, the population of these mutants dropped sharply after 4-10 days. This defect is termed "Stationary-Phase-Death". Each mutant strain was hypersensitive to near-ultraviolet radiation and other oxidative agents. Bovine catalase rescued many of the mutants from death in dormancy, suggesting that specific gene products protect "aged" cells against oxidative damage.

Escherichia coli↗
PubMed1992

Identification and characterization of columbid annexin Icp37. Insights into the evolution of annexin I phosphorylation sites.

Annexin I (AnxI) contains phosphorylation sites in its "hinge region" that have been implicated in the regulation of cell growth and/or differentiation. A pigeon (Columba livia) isoform of this protein, annexin Icp35 (cp35), has a very similar amino acid sequence overall but an unrelated sequence that lacks phosphorylation sites in the hinge region. We now report the identification and characterization of annexin Icp37 (cp37) from pigeon. Genomic cloning and Southern blot analysis demonstrated that cp37 and cp35 were encoded by separated genes. Prolactin induced the expression of cp35 mRNA but not cp37. The amino acid sequence of cp37 was deduced from a cDNA clone and found to share 93 and 75% sequence identity with cp35 and human AnxI, respectively. The amino acid sequence of cp37 bore similarities to both AnxI and cp35 in the critical hinge region. Like AnxI, cp37 contained consensus phosphorylation sites in its amino acid sequence and was phosphorylated on tyrosine by the EGF receptor/kinase and on serine by protein kinase C in vitro. Despite the functional similarities between cp37 and AnxI, the nucleotide sequence that encoded the hinge region of cp37 was very similar to the analogous region of cp35, but different from that of AnxI. We propose that certain features shared by cp37 and AnxI are the products of convergent evolution. The fact that evolution independently selected for two annexin I-like genes (cp37 and anxI) encoding analogous phosphorylation sites is strong evidence that phosphorylation is important for the regulation of the biological activity of these proteins.

Amino Acid Sequence↗
PubMed1992

Interstitial deletion 8p21.3----p23.1 in a 6-year-old girl.

We present a 6-year-old mentally retarded girl. Chromosome analysis showed an interstitial deletion of chromosome 8; 46,XX,del(8) (pter----p23.1::p21.3----qter). The proposita had normal activities of glutathione synthetase reductase (GSR) and factor VII. Parental chromosomes were normal.

Child↗
PubMed1992

Inhibition of protein kinase C by annexin V.

Annexin V is a protein of unknown biological function that undergoes Ca(2+)-dependent binding to phospholipids located on the cytosolic face of the plasma membrane. Preliminary results presented herein suggest that a biological function of annexin V is the inhibition of protein kinase C (PKC). In vitro assays showed that annexin V was a specific high-affinity inhibitor of PKC-mediated phosphorylation of annexin I and myosin light chain kinase substrates, with half-maximal inhibition occurring at approximately 0.4 microM. Annexin V did not inhibit epidermal growth factor receptor/kinase phosphorylation of annexin I or cAMP-dependent protein kinase phosphorylation of the Kemptide peptide substrate. Since annexin V purified from both human placenta and recombinant bacteria inhibited protein kinase C activity, it is not likely that the inhibitor activity was associated with a minor contaminant of the preparations. The following results indicated that the mechanism of inhibition did not involve annexin V sequestration of phospholipid that was required for protein kinase C activation: similar inhibition curves were observed as phospholipid concentration was varied from 0 to 800 micrograms/mL; the extent of inhibition was not significantly affected by the order of addition of phospholipid, substrate, or PKC, and the core domain of annexin I was not a high-affinity inhibitor of PKC even though it had similar Ca2+ and phospholipid binding properties as annexin V. These data indirectly indicate that inhibition occurred by direct interaction between annexin V and PKC. Since the concentration of annexin V in many cell types exceeds the amounts required to achieve PKC inhibition in vitro, it is possible that annexin V inhibits PKC in a biologically significant manner in intact cells.

Annexin A5↗
PubMed1992

Chemotaxis of metastatic tumor cells: clues to mechanisms from the Dictyostelium paradigm.

Amoeboid movement, and in some cases, amoeboid chemotaxis, is a key step in tumor metastasis. The high degree of conservation in signal transduction pathways and motile machinery in eukaryotic cells suggests that insights and molecular probes developed from the study of these processes in easily manipulated experimental model systems will be applicable directly to experimentally intractable tumor cells. One such model system, Dictyostelium discoideum, is discussed in terms of the molecular events involved in amoeboid chemotaxis. The application of insights and assays developed with Dictyostelium to early events in the chemotaxis of Lewis lung carcinoma cells is reviewed.

Actins↗
PubMed1992

Prevention of hyperbaric-associated middle ear barotrauma.

STUDY OBJECTIVE: To determine the efficacy of topical nasal decongestant in the prevention of middle ear barotrauma in patients undergoing hyperbaric oxygen therapy. DESIGN: Prospective, parallel, double-blind, randomized trial. SETTING: University-affiliated community hospital emergency department with hyperbaric oxygen facilities. PARTICIPANTS: Sixty patients undergoing hyperbaric oxygen therapy; 30 subjects in each treatment arm. INTERVENTIONS: After randomization, consenting patients were given two sprays of oxymetazoline hydrochloride or sterile water, 15 minutes before hyperbaric oxygen therapy. Collected data included patient demographics, ear examinations before and after hyperbaric oxygen treatment, and subjective ear complaints. The otoscopic appearance of the tympanic membrane was graded according to the amount of hemorrhage in the eardrum, with Teed scores ranging from 0 (symptoms only) to 5 (gross hemorrhage and rupture). RESULTS: The treatment groups were similar with regard to age, sex, and medical history. Ear discomfort during hyperbaric oxygen therapy was present in 63% (19 of 30) of those receiving oxymetazoline versus 67% (20 of 30) of the control group (P = .99). Likewise, both groups had similar Teed scores after hyperbaric oxygen therapy (P = .88). No adverse effects were noted. CONCLUSION: The results of this pilot study suggest that topical decongestants may not be effective in preventing middle ear barotrauma during hyperbaric oxygen therapy.

Administration, Topical↗
PubMed1992

Pseudoephedrine for the prevention of barotitis media: a controlled clinical trial in underwater divers.

STUDY OBJECTIVE: To determine the efficacy and safety of decongestant prophylaxis among first-time underwater divers in the prevention of barotitis media (middle ear squeeze). DESIGN: Randomized, double-blind, prospective clinical trial. SETTING: Recreational diving schools in Panama City, Florida. TYPE OF PARTICIPANTS: One hundred twenty volunteer scuba divers under the supervision of certified instructors. INTERVENTIONS: After randomization, each subject received a 60-mg tablet of pseudoephedrine or placebo 30 minutes before diving. Prospective data were collected, including subject demographics, signs and symptoms of middle ear squeeze during the dive, and possible drug side effects. The otoscopic appearance of the tympanic membrane was graded according to the amount of hemorrhage in the eardrum, with Teed scores ranging from 0 (normal) to 5 (gross hemorrhage and rupture). chi 2 and t-tests were applied with significance set at P less than .05). The Mantel-Haenszel test was used to test the null hypothesis that the mean Teed scores of the two treatment groups were equal. RESULTS: A total of 116 subjects met the inclusion criteria and completed the study; 60 received 60 mg pseudoephedrine, and 56 received placebo. The treatment groups were similar with regard to age, sex, medical history, and depth of the first dive (P greater than .5). Ear discomfort and blockage during the dive were present in 8% (five of 60) of those receiving pseudoephedrine versus 32% (18 of 56) of the control group (P = .001). Similarly, the pseudoephedrine group had smaller Teed scores after diving than did the control subjects (P = .003). Adverse effects were minimal; two patients experienced dizziness and nausea. CONCLUSION: These results suggest that the use of an oral decongestant before diving decreases the incidence and severity of middle ear squeeze in novice divers.

Adult↗
PubMed1992

A candidate mouse model for Prader-Willi syndrome which shows an absence of Snrpn expression.

The best examples of imprinting in humans are provided by the Angelman and Prader-Willi syndromes (AS and PWS) which are associated with maternal and paternal 15q11-13 deletions, respectively, and also with paternal and maternal disomy 15. The region of the deletions has homology with a central part of mouse chromosome 7, incompletely tested for imprinting effects. Here, we report that maternal duplication for this region causes a murine imprinting effect which may correspond to PWS. Paternal duplication was not associated with any detectable effect that might correspond with AS. Gene expression studies established that Snrpn is not expressed in mice with the maternal duplication and suggest that the closely-linked Gabrb-3 locus is not subject to imprinting. Finally, an additional new imprinting effect is described.

Animals↗