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B Powell

Publications and source records attributed to B Powell.

At least 55 records · Page 3Linked to original sources
PubMed1997

Peptidylarginine deiminase of the hair follicle: characterization, localization, and function in keratinizing tissues.

The enzyme peptidylarginine deiminase (PAD; EC 3.5.3.15) is responsible for the formation of protein-bound citrulline, a major amino acid in the inner root sheath (IRS) and in the medulla of the hair follicle. From mainly biochemical evidence, it is known that the substrate for the enzyme is trichohyalin and that trichohyalin granules gradually disappear to form a matrix with intermediate-like filaments in the IRS cells. In the medulla, the granules aggregate into large masses without filaments. The proteins in both the IRS and medulla are finally cross-linked by transglutaminase. A corollary of the apparent central role of PAD acting on the trichohyalin protein in these processes is that it should be present in the IRS and medulla cells, coincident with trichohyalin. Hair-follicle PAD has not previously been isolated. In the current study, the enzyme was isolated from wool follicles of adult sheep and peptide sequences were used to design DNA primers for the synthesis of PCR products from follicle mRNA. Subsequently, a PAD-specific complementary RNA probe and a trichohyalin complementary RNA probe were prepared for localization studies by in situ hybridization in wool follicles and the epithelia of the rumen, embryonic hoof, and tongue papillae. The experiments have revealed a striking co-expression of PAD and trichohyalin in all of these tissues. The amino acid sequence of the wool-follicle PAD molecule has been deduced from sequencing of the cloned PCR products.

Amino Acid Sequence↗
PubMed1997

Decision making by parents and healthcare professionals when considering continued care for pediatric patients with cancer.

PURPOSE/OBJECTIVES: To better define the treatment-related decisions considered most difficult by parents of pediatric patients with cancer and the factors that influenced their final decisions. DESIGN: Retrospective-descriptive design. SETTING: Pediatric oncology institution in the mid-southern region on the United States. SAMPLE: 39 parents representing 37 of 83 eligible families, 16 attending physicians, three nurses, and two chaplains. METHODS: Parent participants responded by telephone to six open-ended interview questions and a 15-item questionnaire about factors that were important when making the decision to continue care. Healthcare professionals were interviewed face-to-face. MAIN RESEARCH VARIABLES: Most difficult treatment-related decisions; factors influencing decision making. FINDINGS: Parents reported 15 types of difficult decisions, the majority of which were made late in the course of treatment. Deciding between a phase I drug study or no further treatment (n = 14), maintaining or withdrawing life support (n = 11), and giving more chemotherapy or giving no further treatment (n = 8) were the most frequently reported difficult decisions. Parents rated "recommendations received from healthcare professionals" as the questionnaire factor most important in their decision making, and healthcare professionals rated "discussion with the family of the patient" as the most important factor. CONCLUSION: Parents of children or adolescents with cancer and their healthcare providers face difficult treatment-related decisions, many of which occur late in the course of treatment. Parents and healthcare professionals cite similar factors in their decision making but differ in their ratings of the factors' importance. For parents, the information and recommendations they receive from healthcare professionals figure most frequently and most importantly in their decision making. For healthcare professionals, the certainty that the patient will not get better and discussions with the patient's family figure most importantly in their decision making. Once parents conclude that their child can not get better, they are more likely to choose noncurative options such as choosing no further treatment or withdrawing life support. IMPLICATIONS FOR NURSING PRACTICE: Nurses can help determine what information parents need in their decision making. Particular attention must be given to ways to communicate the likelihood of the their child's survival.

Adolescent↗
PubMed1996

Usefulness and limitations of serum and urine lysozyme levels in the classification of acute myeloid leukemia: an analysis of 208 cases.

The revised French-American-British (FAB) classification system for acute myeloid leukemia (AML) recommends the determination of serum lysozyme (SL) or urine lysozyme (UL) levels as an aid in distinguishing acute myeloblastic leukemia with maturation (FAB M2) from acute myelomonocytic leukemia (M4). We reviewed retrospectively 208 cases of adult leukemia in which SL and/or UL were obtained. Elevated lysozyme levels were not found in any of the M0, M3, or M7 cases, but were increased (false positive) in three (14%) M1 cases, 18 (19%) M2 cases and one (20%) M6 case. Although a UL value in excess of 3x normal was found in most cases of AML M4 and M5, only five (11%) M4 cases and three (20%) M5 cases had SL elevations of this magnitude. Lysozyme levels need to be interpreted in conjunction with other parameters for FAB classification.

Aged↗
PubMed1996

The use of large loop excision of the transformation zone (LLETZ) in an outpatient setting.

An audit of the results of 129 patients treated in the first 12 months of operation of an outpatient large loop excision of the transformation zone (LLETZ) clinic was performed. It confirmed the efficacy of the procedure in treatment of cervical intraepithelial neoplasia (CIN) with a cure rate of 93.8%. Major deficiencies identified were the lack of compliance with recommended follow-up, a major discrepancy between predicted diagnosis on colposcopically directed punch biopsy and LLETZ specimen histology, and a large proportion of LLETZ specimens which had negative histology and may be regarded as overtreatment. Suggested strategies to address these include observation of low-grade lesions and treatment with LLETZ at the first clinic appointment.

Adolescent↗
PubMed1995

A study of a new osmotic purgative for colonoscopy. Is Golytely worth its salt?

An osmotic laxative containing polyethylene glycol and sodium sulfate (Golytely Braintree Laboratories, Inc., Braintree, MA) is widely used to clean the colon for colonoscopy. However, its salty taste makes the mixture unpalatable. We therefore tested the claim that a similar solution but without sodium sulfate (Golytely-RSS Braintree Laboratories, Inc., Braintree, MA) makes preparation of the colon more acceptable to patients in a double-blinded randomized controlled trial. Colonic preparation using polyethylene glycol with or without sodium sulfate was randomized in 100 patients due to undergo colonoscopy. The overall acceptability of the regimen was measured on a linear analogue scale and an estimate of symptoms was obtained. Body weight and serum electrolytes, urea, creatinine, hemoglobin and hematocrit were determined before and after preparation in order to assess fluid absorption. The efficacy of colonic cleansing was graded by the colonoscopist. Four patients did not complete the protocol, 47 received the regimen containing sodium sulfate and 49 received the regimen without it. The two groups did not differ in age or body mass. There was no statistical difference in the overall acceptability of the two regimens to the patients (median acceptability rating 74 for regimen with sodium sulfate, range 4-100 compared with 77 for regimen without, range 3-100, p = 0.32, Mann-Whitney test). Nor was there any difference in taste, nausea, vomiting, cramping or perianal discomfort or in the endoscopists' rating of the cleanliness of the colon. The serum sodium concentration rose slightly (mean 1.6 mmol/L) when the regimen with sodium sulfate was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Cathartics↗
PubMed1995

Targeted expression of SV40 T antigen in the hair follicle of transgenic mice produces an aberrant hair phenotype.

Directed expression of SV40 large T antigen (TAg) in transgenic mice can induce tissue-specific tumorigenesis and useful cell lines exhibiting differentiated characteristics can be established from resultant tumor cells. In an attempt to produce an immortalised mouse hair follicle cortical cell line for the study of hair keratin gene control, SV40 TAg expression was targeted to the hair follicles of transgenic mice using a sheep hair gene promoter. Expression of SV40 TAg in the follicle cortex disrupted normal fiber ultrastructure, producing a marked phenotypic effect. Affected hairs were wavy or severely kinked (depending on the severity of the phenotype) producing an appearance ranging from a ruffled coat to a stubble covering the back of the mouse. The transgenic hairs appeared to be weakened at the base of the fibers, leading to premature hair-loss and a thinner pelage, or regions of temporary nudity. No follicle tumors or neoplasia were apparent and immortalisation of cortical cells could not be established in culture. In situ hybridisation studies in the hair follicle using histone H3 as a cell proliferation marker suggested that cell proliferation had ceased prior to commencement of K2.10-TAg expression and was not re-established in the differentiating cortical cells. Hence, TAg was unable to induce cell immortalisation at that stage of cortical cell differentiation. However, transgenic mice developed various other abnormalities including vertebral abnormalities and bladder, liver and intestinal tumors, which resulted in reduced life expectancy.

Animals↗
PubMed1995

To Russia with love.

Explore the source record for details and available documents.

Admitting Department, Hospital↗
PubMed1993

Prolonged subcutaneous administration of recombinant alpha 2b interferon in patients with previously untreated Philadelphia chromosome-positive chronic-phase chronic myelogenous leukemia: effect on remission duration and survival: Cancer and Leukemia Group B study 8583.

We investigated whether recombinant alpha 2b interferon (r alpha 2bIFN) would reduce the proportion of bone marrow Philadelphia chromosome (Ph) cells in chronic-phase chronic myelogenous leukemia (CML) by treating 107 previously untreated patients daily with r alpha 2bIFN at 5 x 10(6)IU/m2 subcutaneously. Patients with complete remission, partial remission, or partial hematologic remission received treatment until progression; those with progressive disease were taken off study and observed for survival. Sixty-three (59%) of the patients achieved at least a partial hematologic remission (24 complete remissions and 39 partial remissions). The median time to response for the 63 responders was 3.4 months, with a median duration of remission of 52 months and with 81% of responders continuing in remission beyond 12 months. The median survival for the 107 patients was 66 months. Of 78 patients with cytogenetic follow-up data, 31 (40%) achieved a partial cytogenetic response (n = 17) or a complete cytogenetic response (n = 14). The percentage of cytogenetic responders among all patients was 29% (31 of 107 patients). The median time to first cytogenetic response was 9 months. A major dose reduction of r alpha 2bIFN (> or = 50%) was required at some time during treatment in 38% of patients, 26% required 10% to 49% dose reductions, and 36% had minor dose reductions of < or = 10%. No association was observed between dose received and the attainment of a cytogenetic response. None of the usual prognostic factors (sex, race, performance status, weight loss, time from diagnosis to treatment, hepatosplenomegaly, age, symptoms, hemoglobin, or platelet, blast, basophil, or white blood cell count) were significantly related to survival. These data provide confirmation that major cytogenetic responses to prolonged administration of subcutaneous r alpha 2bIFN occur in 20% to 38% (95% confidence interval) of chronic-phase Ph-positive patients. Although it is hypothesized that patients achieving major cytogenetic responses to r alpha 2bIFN should have prolonged remission duration and survival compared with nonresponders, analyses of the effect of cytogenetic responders by both "landmark" and time-dependent covariate techniques fail to provide statistically significant evidence for an effect of cytogenetic response on remission duration or survival. This may be due in part to an effect size insufficiently large to be detected with the number of patients treated in this study. Thus, confirmation of remission duration or survival benefit, if any, of r alpha 2bIFN therapy in Ph-positive chronic-phase CML must await the outcome of randomized trials comparing IFN with conventional agents.

Adolescent↗
PubMed1993

Functional role of the glycan cluster of the human immunodeficiency virus type 1 transmembrane glycoprotein (gp41) ectodomain.

To examine the role of the glycans of human immunodeficiency virus type 1 transmembrane glycoprotein gp41, conserved glycosylation sites within the env sequence (Asn-621, Asn-630, and Asn-642) were mutated to Gln. The mutated and control wild-type env genes were introduced into recombinant vaccinia virus and used to infect BHK-21 or CD4+ CEM cells. Mutated gp41 appeared as a 35-kDa band in a Western blot (immunoblot), and it comigrated with the deglycosylated form of wild-type gp41. Proteolytic cleavage of the recombinant wild-type and mutant forms of the gp160 envelope glycoprotein precursor was analyzed by pulse-chase experiments and enzyme-linked immunosorbent assay: gp160 synthesis was similar whether cells were infected with control or mutated env-expressing recombinant vaccinia virus, but about 10-fold less cleaved gp120 and gp41 was produced by the mutated construct than the control construct. The rates of gp120-gp41 cleavage at each of the two potential sites appeared to be comparable in the two constructs. By using a panel of antibodies specific for gp41 and gp120 epitopes, it was shown that the overall immunoreactivities of control and mutated gp41 proteins were similar but that reactivity to epitopes at the C and N termini of gp120, as present on gp160 produced by the mutated construct, was enhanced. This was no longer observed for cleaved gp120 in supernatants. Both gp120 proteins, from control and mutated env, were expressed on the cell surface under a cleaved form and could bind to membrane CD4, as determined by quantitative immunofluorescence assay. In contrast, and despite sufficient expression of env products at the cell membrane, gp41 produced by the mutated construct was unable to induce membrane fusion. Therefore, while contradictory results reported in the literature suggest that gp41 individual glycosylation sites are dispensable for the bioactivity and conformation of env products, it appears that such is not the case when the whole gp41 glycan cluster is removed.

Base Sequence↗
PubMed1992

Hair follicle differentiation: expression, structure and evolutionary conservation of the hair type II keratin intermediate filament gene family.

During hair follicle development several cell streams are programmed to differentiate from the cell population of the follicle bulb. In the hair cells, a number of keratin gene families are transcriptionally activated. We describe the characterization of the type II keratin intermediate filament (IF) gene family which is expressed early in follicle differentiation. In sheep wool, four type II IF proteins are expressed. One gene has been completely sequenced and the expression of three of the genes examined in detail. The sequenced gene encodes a 55 x 10(3) Mr protein of the type II keratin IF protein family, designated KII-9 in the new nomenclature we have adopted and described in the Introduction. The gene has a similar exon/intron structure to the epidermal type II keratin IF genes. In situ hybridization experiments show that the genes are expressed in the hair cortical cells but not in the cells of the outer root sheath, inner root sheath or medulla. During hair keratinocyte differentiation the type II IF genes are sequentially activated and coexpressed in the same cells. Expression is first detected in cells in the middle of the follicle bulb located near the dermal papilla and, subsequently, two of the genes are transcriptionally activated in the differentiating keratinocytes as they migrate upwards, in the upper part of the bulb. A fourth type II IF gene is activated later. The genes with the same expression pattern are also closely related in sequence and a number of conserved elements are present in the promoters of those genes, including a novel element which is also found in the promoter of a coexpressed type I IF gene and three other hair keratin genes.

Amino Acid Sequence↗
PubMed1992

Performance characteristics of contemporary hemodialysis and venovenous hemofiltration in acute renal failure.

UNLABELLED: Modality choice in the treatment of acute renal failure (ARF) should be based on the match between individual patient needs and the characteristics of available therapies. Considerations include access, risk of bleeding, hemodynamic instability, and ability to remove excess volume. We prospectively studied 547 consecutive treatments for ARF in 110 patients to determine the performance features of modalities based on single-vessel venous access: hemodialysis (HD) and venovenous hemofiltration (VVH). All treatments were performed in an 18-month period at a single center. Patients' ages ranged from 16 to 84 years; 26 were trauma cases; 69 patients expired during their hospitalization. Mean number of treatments per patient was 4.97. Mean treatment duration was 197 min. Heparin was used unless active bleeding was present or felt to be a high risk; mean dose required was 2628 units. Pressor therapy was in progress prior to initiation of 260 (48%) of treatments. RESULTS: pretreatment and posttreatment mean systolic and diastolic BP were unchanged for the group. Forty-three (7.9%) treatments were terminated prematurely; of these only 27 (4.9%) were due to hypotension. No patient developed clinically apparent bleeding during any treatment. Contemporary equipment and techniques allow for provision of high-quality intermittent therapy for ARF, with excellent hemodynamic stability. Shorter, single-vein access treatments are advantageous for severely ill or injured patients who often undergo invasive monitoring and multiple studies or procedures.

Acute Kidney Injury↗
PubMed1991

Perceptual dysfunction in hemiplegia and automobile driving.

Sixteen post-stroke, hemiplegic patients, who requested that they be allowed to return to driving, were extensively evaluated by a physiatrist, psychologist, occupational therapist, and driver training specialist. After they completed a driver training program, the patients were divided into three groups based on their driving program success and follow-ups. Significant differences in the psychological test results were found between Group I (those who drove without any difficulty) and Groups II and III (those who drove limited distance or who failed driver training). Results suggest that patients with significant cognitive and perceptual problems who take training and limit their driving can be safe drivers when they return to driving.

Accidents, Traffic↗
PubMed1990

Enhanced anti-tumour activity of carmustine (BCNU) with tumour necrosis factor in vitro and in vivo.

The effects on experimental melanoma of a combination of recombinant human tumour necrosis factor alpha (rhTNF alpha) and carmustine (BCNU) were studied in vitro and in vivo. In vitro, BCNU alone was cytotoxic to murine B16 melanoma cells, and at all concentrations of BCNU this toxicity was increased by the addition of TNF. In vivo, BCNU and TNF, when given separately, caused tumour growth delay of B16 melanoma and of human melanoma xenografts in immune-deprived mice. The combination of TNF at low dose 2.5 x 10(5) U kg-1 = 122 ng kg-1) with BCNU (35 mg kg-1) resulted in significant growth delay (compared with either drug alone) in B16 melanoma (P = 0.005). There was no significant increase in toxicity as assessed by weight loss and peripheral blood counts. Experiments with human melanoma xenografts yielded similar results (P = 0.001) but only at higher doses of TNF (1 x 10(6) U kg-1 = 489 ng kg-1). The enhancement of BCNU cytotoxicity by TNF may be important if it can be translated into patients with melanoma. A randomised study is now underway to investigate the clinical potential of this observation.

Animals↗
PubMed1990

VirA, a coregulator of Ti-specified virulence genes, is phosphorylated in vitro.

High-level expression of a chimeric virA gene was obtained by replacing the first 524 codons of virA with the first half of trpE. The encoded fusion protein was isolated and found to exhibit autokinase activity. Therefore, a kinase domain is in the C-terminal portion of VirA, and protein phosphorylation may be an important feature of VirA function.

Bacterial Proteins↗