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Biomedical subjects

K Powell

Publications and source records attributed to K Powell.

At least 73 records · Page 4Linked to original sources
PubMed1990

Helicobacter pylori infection treated with a tripotassium dicitrato bismuthate and metronidazole combination.

Seventy-two patients with H. pylori infection in their antral mucosa took part in the study. Forty-three received metronidazole 400 mg t.d.s. for two weeks, plus De-Nol tabs 2 b.d. for four weeks, and the remaining 29 patients received metronidazole 400 mg t.d.s. for two weeks plus De-Nol liquid 5 ml q.d.s. for four weeks. Seven of 57 H. pylori isolates were found to have pre-treatment metronidazole resistance. Success, in terms of eradication of H. pylori, was assessed using a one-month post-treatment 14C urea breath test. Successful eradication of H. pylori was achieved in 72% and 79%, respectively, of the metronidazole/De-Nol tablet and metronidazole/De-Nol liquid groups. These figures increased to 87% and 84%, respectively, if the patients whose organisms were known to be metronidazole-sensitive were considered in isolation. H. pylori was successfully eradicated in only one of seven patients with a metronidazole-resistant organism.

Aged↗
PubMed1990

Prevention of bacteremia attributed to luminal colonization of tunneled central venous catheters with vancomycin-susceptible organisms.

Forty-five children with oncologic or hematologic disorders requiring tunneled central venous catheters (TCVC) for the administration of immunosuppressive therapy were randomized to receive either 10 U/mL heparin (H) (24 patients) or a solution of 10 U/mL H and 25 micrograms/mL vancomycin (H-V) (21 patients) for all catheter flushes. Episodes of fever or suspected sepsis were evaluated to determine whether the addition of vancomycin to the flush solution would alter the incidence of symptomatic bacteremia attributed to luminal colonization of TCVC with vancomycin-susceptible bacteria. Patients were enrolled for 247 +/- 150 days, accounting for a total of 11,095 days of catheter use. Bacteremia attributed to luminal colonization with vancomycin-susceptible organisms occurred in five patients (six infections) receiving H alone compared with zero patients receiving H-V (P = .035). The time to the first episode of bacteremia with vancomycin-susceptible organisms, analyzed by Kaplan-Meier survival curves, was significantly longer in patients receiving H-V (P = .04). There were no differences in the incidence of other infections including bacteremia attributed to luminal colonization with vancomycin-resistant organisms, other bacteremias (including those arising from the catheter exit site), exit-site cellulitis, or fungal infections. No organisms resistant to vancomycin were identified. Vancomycin could not be detected in the peripheral blood of patients receiving vancomycin in the flush solution. No vancomycin-related toxicities were noted. We conclude that the use of an H-V flush solution in immunocompromised patients with TCVC can decrease the frequency of bacteremia attributed to luminal colonization with vancomycin-susceptible bacteria.

Adolescent↗
PubMed1989

The DST in children and adolescents with major depressive disorder.

The authors analyzed dexamethasone suppression test (DST) results from 13 prospective studies on the use of the DST in children and adolescents with psychiatric disorders. Sensitivity of the DST was significantly higher among the children than among the adolescents with major depressive disorder (69.6% and 47.1%, respectively), and specificity was significantly lower (69.7% and 80.2%). Significantly more adolescents with major depressive disorder than with other psychiatric diagnoses, especially conduct disorder, were nonsuppressors. The authors discuss possible explanations for the high DST sensitivity among the children and point out the potential usefulness of the DST in differentiating major depressive disorder from conduct disorder.

Adolescent↗
PubMed1988

The dexamethasone suppression test in children and adolescents with major depressive disorder: a review.

The authors review the available studies on the use of the dexamethasone suppression test (DST) in children and adolescents with psychiatric disorders. For the purposes of analysis, the authors divided the studies according to the two age groups. Pooled sensitivity, specificity, and positive predictive power were calculated for each age group per diagnostic category. DST nonsuppression among subjects with major depressive disorder (MDD) in the children's group was 69.6%, with a specificity of 69.7%, whereas for adolescent subjects, DST sensitivity was 41.3%, and specificity was 79.3%. The positive predictive power of an abnormal DST result in helping diagnose MDD in the children's group was 69.7%, whereas for the adolescent group, the positive predictive power was 66.6%. The authors conclude that the evidence cannot support the routine clinical use of the DST in children and in adolescents, but there may be a research role for the DST in these patient populations.

Adolescent↗
PubMed1987

AIDS virus reverse transcriptase defined by high level expression in Escherichia coli.

The causative agent of AIDS the human immunodeficiency virus (HIV) encodes as part of its pol gene a reverse transcriptase (RT) which has a key role in the replication of the virus and thus constitutes an ideal target for antiviral chemotherapy. The purified HIV RT from virus particles consists of two related polypeptides of 66 and 51 kd mol. wt and similar polypeptides are found on expression of the complete HIV pol gene using prokaryotic systems. Here we describe the expression of the 66-kd protein in Escherichia coli and demonstrate that this polypeptide alone has authentic RT activity. Thus, a central HIV pol gene segment encodes and is sufficient for high levels of RT activity. The RT has been purified from E. coli extracts using a purification procedure involving two chromotography steps resulting in an enzyme preparation near homogeneity. Deletion of the C-terminal region of the RT thought to encode the RNase H domain resulted in loss of polymerase activity.

Cloning, Molecular↗
PubMed1981

Tamoxifen-induced hypercalcemia in breast cancer.

Among 470 patients with metastatic breast cancer treated with tamoxifen, ten patients (2.3%) developed hypercalcemia. All patients with hypercalcemia had osteolytic or mixed lytic and blastic bone metastases. Hypercalcemia developed after a median period of seven days (range 4-11 days) of tamoxifen administration. Hypercalcemia was treated with conventional measures and serum calcium levels normalized in nine patients, either with a brief interruption of tamoxifen therapy or in spite of continued treatment. Four patients experienced partial remissions with continued tamoxifen therapy. These results indicate that hypercalcemia is a potentially serious complication of tamoxifen therapy but is generally short-lived, and can be controlled with supportive measures, thus allowing continued tamoxifen administration.

Aged↗
PubMed1981

Results of local excision and radical radiotherapy in early breast cancer.

Twenty-seven patients with a T1 or T2 N0M0 breast carcinoma were treated by local excision of the lump followed by radical radiotherapy, using orthovoltage X-rays. The crude survival rate was 100% at three years, 92% at five years, 95% at 10 years. The local recurrence rate was 8% at three years, 12% at five years, 10.5% at 10 years. The radiation dose needed to be tumour lethal is discussed. Our results and those of papers quoted indicate that 4500--5000 cGy (rad) in five weeks, given in five fractions per week, is optimal, provided the primary tumour has ben removed. A further 1000--2000 cGy to the lumpectomy site reduces the incidence of local recurrence. The cosmetic results of our treatment are illustrated. Some telangiectasis was seen but the general appearance and texture of the treated breasts was satisfactory.

Adult↗
PubMed1980

Improved conversion of methanol to single-cell protein by Methylophilus methylotrophus.

The glutamate dehydrogenase gene of Escherichia coli has been cloned into broad host-range plasmids and can complement glutamate synthase mutants of Methylophilus methylotrophus. Assimilation of ammonia via glutamate dehydrogenase is more energy-efficient than via glutamate synthase, thus the recombinant organism converts more growth substrate, methanol, into cellular carbon.

Adenosine Triphosphate↗