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Biomedical subjects

D Webb

Publications and source records attributed to D Webb.

At least 73 records · Page 4Linked to original sources
PubMed1995

Congenital astroblastoma: an immunohistochemical study. Case report.

Astroblastoma is a rare type of glial tumor, usually occurring in older children and young adults. It has a distinctive histological appearance that is characterized by a radiating arrangement of tumor cells that form perivascular pseudorosettes. The authors report only the second case of astroblastoma presenting in congenital form. Following subtotal tumor resection, the infant received 10 courses of chemotherapy consisting of vincristine, etoposide, and carboplatinum. Evidence is presented for a tumor response to chemotherapy, a previously unreported observation. The child is alive 2.5 years after diagnosis with satisfactory functional status. Immunohistological and ultrastructural features of this tumor are presented. The discussion focuses on the biology, natural history, and management of this unusual neoplasm.

Astrocytoma↗
PubMed1995

What do palliative staff think about audit?

Forty-one of 68 palliative care clinicians responded to an anonymous questionnaire assessing the attitudinal, training, management, and support needs for introducing audit. Most respondents (88%) felt it was a good idea; reservations concerned the increase in work load. Although 66% of respondents had received audit training, only 39% were currently involved in audit. Respondents identified a need for more information and feedback, experienced assistance, and support. These concerns have to be addressed by health care managers if audit is to be successfully maintained. Current training sessions do not adequately meet staff needs; palliative care staff require an advanced audit training that includes staff motivation, analysis of results, and the provision of feedback.

Attitude of Health Personnel↗
PubMed1995

Survey of lead exposure around a closed lead smelter.

OBJECTIVE: To test the hypothesis that elevated lead in soil is positively correlated with blood lead (BPb) levels in children in an urban population surrounding a closed lead smelter, a US Environmental Protection Agency Superfund clean-up site was surveyed. METHOD: A total of 827 volunteers including 490 children under 6 years of age participated. A questionnaire was administered. Blood lead was determined as was lead content of samples of house dust, soil, paint, and water of the participants' homes. RESULTS: The arithmetic mean venous BPb in 490 children between 6 and 72 months of age was 6.9 micrograms/dL (0.33 mumol/L) range 0.7 to 40.2 micrograms/dL (0.03 to 1.94 mumol/L). The BPb of 78 (16%) children in this group was > or = 10 micrograms/dL (0.48 mumol/L). Based on multiple regression modeling, lead in house dust accounted for 18% of the variance in BPb. Lead in paint together with the condition of the house were the main contributors to the dust lead variance (26%) with soil lead accounting for an additional 6%. Lead in paint alone accounted for 3% of the BPb variance. Lead in paint together with the condition of the house accounted for 12% of BPb variance, and lead in soil accounted for an additional 3%. Factors other than environmental lead such as education of parents, household income, and behavior were associated with BPb levels. CONCLUSIONS: The mean BPb in children was below the present level of concern of the Centers for Disease Control and Prevention. Children with BPb of > or = 10 micrograms/L (0.48 mumol/L) tended to live in poorly maintained older houses. Based on these findings lead in soil and paint in well-maintained homes contributed little to the lead exposure of children.

Child, Preschool↗
PubMed1995

Nature of HLA-associated predisposition to childhood acute lymphoblastic leukemia.

A molecular analysis was carried out in 63 sequentially diagnosed childhood acute lymphoblastic leukemia (ALL) patients and 1011 controls to investigate the homozygosity rate for HLA-DR53. HLA-DR53 is associated with acute myeloblastic leukemia at the protein level, and our previous study has shown its association with early-onset chronic myeloid leukemia only in homozygous form at the DNA level. In the present study, the homozygosity rates for DR53 were 17.5 and 13.6% in patients and controls, respectively. Ten of the 11 homozygous patients were boys. In the common ALL group (n = 40), all seven DR53 homozygous patients were boys, and among 19 girls this genotype was not observed (P = 0.006). For males, homozygosity for DR53 revealed a relative risk (RR) of 3.29 (P = 0.008) for common ALL. Five of the 11 relapsed patients were homozygous for DR53. Heterozygous frequencies for HLA-DR53 were not different between patients and controls. Homozygosity for DR53 was associated with a very high relapse rate (45.5 vs 7.7%, P = 0.002, RR = 9.1). These results extended our findings in chronic myeloid leukemia and showed the recessive nature and the male predominance of the interactive HLA influence on the development of childhood leukemia. Molecular mimicry of an HLA-DR53 epitope by oncogenic (retro)viruses or putative susceptibility genes in linkage disequilibrium with HLA-DR53 may be responsible for this association.

Adolescent↗
PubMed1994

Pendular activity of human upper limbs during slow and normal walking.

When walking at normal and fast speeds, humans swing their upper limbs in alternation, each upper limb swinging in phase with the contralateral lower limb. However, at slow and very slow speeds, the upper limbs swing forward and back in unison, at twice the stride frequency of the lower limbs. The change from "single swinging" (in alternation) to "double swinging" (in unison) occurs consistently at a certain stride frequency for agiven individual, though different individuals may change at different stride frequencies. To explain this change in the way we use our upper limbs and individual variations in the occurrence of the change, the upper limb is modelled as a compound pendulum. Based on the kinematic properties of pendulums, we hypothesize that the stride frequency at which the change from "single swinging" to "double swinging" occurs will be at or slightly below the natural pendular frequency (NPF) of the upper limbs. Twenty-seven subjects were measured and then filmed while walking at various speeds. The mathematically derived NPF of each subject's upper limbs was compared to the stride frequency at which the subject changed from "single swinging" to "double swinging." The results of the study conform very closely to the hypothesis, even when the NPF is artificially altered by adding weights to the subjects' hands. These results indicate that the pendulum model of the upper limb will be useful in further investigations of the function of the upper limbs in human walking.

Adolescent↗
PubMed1993

Pharmacokinetics of 18F-labeled fluconazole in healthy human subjects by positron emission tomography.

The distribution of fluconazole in tissue of human volunteers was determined by positron emission tomographic scanning over a 2-h period following the infusion of a tracer dose of 18F-fluconazole (5 to 7 mCi) plus 400 mg of unlabeled drug (the standard daily dose of fluconazole). Previous studies have validated this approach for animals. From serial positron emission tomographic imaging and blood sampling, pharmacokinetics of fluconazole in tissue were determined. There was significant distribution of the radiolabeled drug in all organs studied, with nearly constant levels achieved by 1 h. Plateau concentrations of fluconazole in key organs (micrograms per gram) included the following: whole brain, 4.92 +/- 0.17; heart, 6.98 +/- 0.20; lung, 7.81 +/- 0.46; liver, 12.94 +/- 0.24; spleen, 22.96 +/- 2.5; kidney, 11.23 +/- 0.61; prostate, 8.24 +/- 0.58; and blood, 3.76 +/- 0.30. Since levels of fluconazole of > 6 micrograms/g are needed to treat infection with most strains of Candida and levels of > 10 micrograms/g are needed for Cryptococcus neoformans, Coccidioides immitis, and Histoplasma capsulatum, the following predictions can be made. The current standard dose of 400 mg/day should be more than adequate in the treatment of urinary tract and hepatosplenic candidiasis but problematic in the treatment of candidal osteomyelitis, even with the higher levels that develop after multiple doses. Similarly, higher doses should be considered, particularly in immunocompromised patients, with infection with C. neoformans, H. capsulatum, and C. immitis that involves the central nervous and musculoskeletal systems.

Adult↗
PubMed1993

Susceptibilities of serial Cryptococcus neoformans isolates from patients with recurrent cryptococcal meningitis to amphotericin B and fluconazole.

Amphotericin B and fluconazole susceptibilities of 13 Cryptococcus neoformans isolates from five patients with recurrent cryptococcal meningitis were determined. For each patient, serial isolates showed no increase in antibiotic resistance relative to the initial isolate. For these patients, recurrent disease was not due to drug resistance but may reflect changes in immune function and/or poor compliance.

AIDS-Related Opportunistic Infections↗
PubMed1993

Isolation of a human T-lymphotropic virus type I strain from Australian aboriginals.

A human T-lymphotropic virus type I (HTLV-I) strain was isolated in a CD4+ T-lymphocyte culture established from a healthy seropositive Australian Aboriginal. This isolate, identified as HTLV-IMSHR-1, was detected by immunofluorescence with monoclonal antibodies, by the presence of gag-encoded protein p24 in the culture supernatant, and by cocultivation leading to infection and transformation of lymphocytes from an HTLV-I-negative donor. By using the polymerase chain reaction technique, the env gene and segments of the pol and pX regions of the proviral genome of HTLV-I(MSHR-1) were amplified and sequenced. Comparison with the envelope sequences of prototype strains revealed up to 7% divergence at the nucleotide level and 3.1 to 4.3% divergence in the predicted amino acid sequence. Phylogenetic analysis showed that the Australian and Melanesian isolates are related. Differential reactivity with monoclonal antibodies suggests that gag protein p19 of HTLV-I(MSHR-1) is also divergent. The potential for antigenic divergence between the prototype HTLV-I isolates and the Austro-Melanesian variants requires further investigation, because it would have implications for serodiagnosis and vaccine development.

Amino Acid Sequence↗
PubMed1993

Evaluation times for patients with in-hospital strokes.

BACKGROUND: Each year at least 35,000 people suffer a stroke while hospitalized, but little is known about the clinical characteristics of such patients or how rapidly they are identified and evaluated. With a recent emphasis on the very early treatment of stroke, in-hospital stroke patients may be candidates for some early interventions. METHODS: This was a retrospective study using the stroke registries at two academic medical centers. Data were collected about the clinical characteristics of patients with an in-hospital stroke and who recognized the stroke. Detailed time data were analyzed to determine the time of stroke recognition, medical evaluation, and neurological evaluation. These specific time epochs were analyzed to determine which were responsible for any delays in stroke identification and assessment. Data were analyzed using nonparametric methods, including the Wilcoxon rank sum and Kruskal-Wallis procedure. RESULTS: Sixty-three patients were identified with in-hospital strokes and adequate time data. In-hospital stroke patients were recognized most frequently by nurses (63%) and by the patient (16%). Patients on a cardiology service and general surgery service accounted for 48% of all in-hospital strokes. The mean and median times from stroke recognition to a neurology evaluation were 14.5 and 2.5 hours, respectively. Total delays differed significantly with service and locale (P = .004). Patients on the Duke neurology service were evaluated significantly sooner (median delay, 0.5 hour) than patients on the Duke medical (median delay, 5.8 hours) or Duke surgical (median delay, 20.5 hours; P < .01 by Wilcoxon rank sum) services. Patients on the Yale surgical service were evaluated significantly sooner than patients on the Duke medical (P = .0006) or surgical (P = .0001) services. The time between physician notification and calling for a neurology evaluation accounted for > 60% of the total time delay for patients not on a neurology service. CONCLUSIONS: A substantial number of in-hospital stroke patients experience a long delay between symptom recognition and a neurological evaluation. While medical personnel are usually notified very soon after an in-hospital stroke is recognized, such patients often do not receive a rapid neurological evaluation. Additional education of hospital staff may reduce these time delays.

Cerebral Infarction↗
PubMed1992

The expression, purification and crystallization of the epsilon subunit of the F1 portion of the ATPase of Escherichia coli.

The epsilon subunit of the F0F1-ATPase from Escherichia coli has been expressed in E. coli as a fusion protein with glutathione S-transferase from the parasitic helminth Schistosoma japonicum. The epsilon subunit released by thrombin treatment of the purified fusion protein carried two amino acid changes, A1G and M2S, and was obtained in a yield of about five milligrams per litre of cultured cells. The two amino acid changes were shown not to affect function. The protein has been crystallized in a form suitable for X-ray diffraction structure analysis. The crystals are hexagonal, space group P6(1)22 (or P6(5)22), with a = b = 94.9 A, c = 57.1 A and gamma = 120 degrees. The diffraction from small crystals extends to at least 2.9 A resolution.

Crystallization↗