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Biomedical subjects

P Barker

Publications and source records attributed to P Barker.

At least 73 records · Page 4Linked to original sources
PubMed1997

A mouse model for the renal salt-wasting syndrome pseudohypoaldosteronism.

Aldosterone-dependent epithelial sodium transport in the distal nephron is mediated by the absorption of sodium through the highly selective, amiloride-sensitive epithelial sodium channel (ENaC) made of three homologous subunits (alpha, beta, and gamma). In human, autosomal recessive mutations of alpha, beta, or gammaENaC subunits cause pseudohypoaldosteronism type 1 (PHA-1), a renal salt-wasting syndrome characterized by severe hypovolemia, high plasma aldosterone, hyponatremia, life-threatening hyperkaliemia, and metabolic acidosis. In the mouse, inactivation of alphaENaC results in failure to clear fetal lung liquid at birth and in early neonatal death, preventing the observation of a PHA-1 renal phenotype. Transgenic expression of alphaENaC driven by a cytomegalovirus promoter in alphaENaC(-/-) knockout mice [alphaENaC(-/-)Tg] rescued the perinatal lethal pulmonary phenotype and partially restored Na+ transport in renal, colonic, and pulmonary epithelia. At days 5-9, however, alphaENaC(-/-)Tg mice showed clinical features of severe PHA-1 with metabolic acidosis, urinary salt-wasting, growth retardation, and 50% mortality. Adult alphaENaC(-/-)Tg survivors exhibited a compensated PHA-1 with normal acid/base and electrolyte values but 6-fold elevation of plasma aldosterone compared with wild-type littermate controls. We conclude that partial restoration of ENaC-mediated Na+ absorption in this transgenic mouse results in a mouse model for PHA-1.

Amiloride↗
PubMed1997

Intensive care for people with serious mental illness.

This article describes the development of a psychiatric 'intensive care' service for men and women with serious or enduring forms of psychotic disorder. The authors suggest that such a residential therapeutic service may be an essential part of the development of community care for the most vulnerable people served by mental health services.

Critical Care↗
PubMed1997

Mental health nursing: making it a primary concern.

This article suggests that the focus of mental health nursing is narrowing at a time when nurses in other areas are widening their roles and responsibilities. The author calls for more co-operation between mental health nurses and their colleagues in primary health care.

Humans↗
PubMed1996

Early death due to defective neonatal lung liquid clearance in alpha-ENaC-deficient mice.

The amiloride-sensitive epithelial sodium channel, ENaC, is a heteromultimeric protein made up of three homologous subunits (alpha, beta and gamma) (1,2). In vitro, assembly and expression of functional active sodium channels in the Xenopus oocyte is strictly dependent on alpha-ENaC--the beta and gamma subunits by themselves are unable to induce an amiloride-sensitive sodium current in this heterologous expression system (2). In vivo, ENaC constitutes the limiting step for sodium absorption in epithelial cells that line the distal renal tubule, distal colon and the duct of several exocrine glands. The adult lung expresses alpha, beta and gamma ENaC (3,4), and an amiloride-sensitive electrogenic sodium reabsorption has been documented in upper and lower airways (3-7), but it is not established whether this sodium transport is mediated by ENaC in vivo. We inactivated the mouse alpha-ENaC gene by gene targeting. Amiloride-sensitive electrogenic Na+ transport was abolished in airway epithelia from alpha-ENaC(-/-) mice. Alpha-ENaC(-/-) neonates developed respiratory distress and died within 40 h of birth from failure to clear their lungs of liquid. This study shows that ENaC plays a critical role in the adaptation of the newborn lung to air breathing.

Animals↗
PubMed1996

Diagnostic indicators in the early recognition of severe cocaine intoxication.

Acute cocaine intoxication is an ever increasing problem in the United Kingdom. Aggressive resuscitation linked to early diagnosis is essential in preventing death. Three cases of severe cocaine toxicity are presented to highlight certain diagnostic indicators in recognising the condition in patients presenting in a collapsed state to the accident and emergency department. Acidosis was a striking feature. The acute management of such patients is supportive and should involve methods to minimize continuing absorption.

Acidosis↗
PubMed1996

Short-course intravenous antibiotics with oral quinolone prophylaxis in the treatment of neutropenic fever in autologous bone marrow or peripheral blood progenitor cell transplant recipients.

The effectiveness of short-course intravenous antibiotics concurrent with prophylactic oral ciprofloxacin in the treatment of neutropenic fever was studied in 81 patients undergoing autologous bone marrow or peripheral blood progenitor cell transplantation (ABMT or PBPCT). During the neutropenic period following ABMT or PBPCT, 10/81 (12%) patients did not require treatment with intravenous antibiotics. Seventy-one patients required antibiotics. Forty-seven of the 71 (66%) responded to 72 h treatment with gentamicin, azlocillin or ceftazidime, and vancomycin. Thirty-three of the 47 (70%) responders had a complete resolution of their fever with no further recurrence. Fourteen of the 47 responders developed a second fever between 2 and 25 days after stopping first-line antibiotics. Eleven of the 14 patients responded to a second course of intravenous antibiotics. Twenty-four of the 71 patients did not respond to intravenous antibiotics and were treated with intravenous amphotericin and the intravenous antibacterial agents were discontinued. Eighteen of the 24 patients responded to amphotericin. The 6 patients who had persistent fever resolved their temperature when their neutrophil count recovered. There were no deaths due to infection during the study. Short-duration intravenous antibiotics in conjuction with oral ciprofloxacin prophylaxis are a safe and effective treatment for neutropenic fever.

Adolescent↗
PubMed1996

Peripheral blood progenitor cell transplantation: a single centre experience comparing two mobilisation regimens in 67 patients.

Between June 1991 and January 1995 we performed 67 peripheral blood progenitor cell transplants (PBPCT). Ten patients (group 1) were mobilised with 7 gm/m2 of cyclophosphamide followed by daily G-CSF injections (5 micrograms/kg, subcutaneously). When the white cell count reached 1 x 10(9)/1 they were leukapheresed for 5 days. After stem cell infusion they received G-CSF (10 micrograms/kg/day) until the neutrophil count reached 1.5 x 10(9)/1. Fifty-six patients had PBPCs mobilised with 3 gm/m2 of cyclophosphamide followed by daily subcutaneous G-CSF (5 micrograms/kg) and PBPCs were harvested on 2 consecutive days, when the white cell count rose to 4 x 10(9)/1. After stem cell infusion this group did not receive G-CSF. In 47 of the 56 patients (group 2) adequate MNC (> or = 4 x 10(8)/kg) and/or CFU-GM (> or = 10 x 10(4)/kg) were obtained. Insufficient MNC and/or CFU-GM were obtained in 10 patients. They were therefore transplanted using a combination of bone marrow and peripheral blood progenitor cells (group 3). Overall 64 patients successfully engrafted. Median days to neutrophils > or = 0.5 x 10(9)/1 were 9 (range 8-13), 12 (range 8-25) and 11 (range 9-16) and to platelets > or = 50 x 10(9)/1 were 11 (range 9-23), 13 (range 9-90) and 16 (range 13-99) in groups 1, 2 and 3 respectively. Patients in group 1 had a faster neutrophil recovery than patients in group 2 (P = 0.0002). The three patients who failed to engraft all received a combination of autologous peripheral blood and bone marrow cells.

Adolescent↗
PubMed1996

High-dose therapy and autologous stem cell rescue for poor risk and refractory lymphoma: a single centre experience of 123 patients.

Over an 8-year period we autografted 123 patient with poor-risk lymphoma. Sixty-three patients had Hodgkin's disease (HD) and 60 non-Hodgkin's lymphoma (NHL). Of the patients with HD, 45 had responsive and 18 resistant disease prior to high-dose therapy. Fifty-three patients with NHL had responsive and seven had resistant disease at the time of transplantation. Seventy-seven patients received autologous bone marrow (BM) rescue, 39 autologous peripheral blood progenitor cell (PBPC) rescue, and seven combined BM and PBPC rescue. High-dose chemotherapy was BEM in 67, BEAM in 39, TBI and cyclophosphamide or etoposide or BCNU in 10, etoposide/mitozantrone in six and etoposide/melphalan in one. There was eight (6.5%) deaths due to treatment-related toxicity, within the first 100 days post-transplantation. Of the patients with HD 41 (65%) are alive at a median follow-up of 39 months (range 2-94). Thirty-three (52%) patients remain in CR. The median DFS of the 63 patients with HD is 34 months (95% CI 7-61). The median DFS for patients transplanted with responsive disease was significantly better than for those transplanted with refractory disease (61 vs 21 months P < 0001). Thirty-five (58%) of the patients with NHL are alive, and 20 (33%) remain in CR. The median DFS for patients transplanted with responsive and refractory disease was 11 months (95% CI 3-19) and 4 months (95% CI 0-9; P = NS) respectively. The median DFS for patients transplanted with HD was significantly better than for patients transplanted with NHL (34 vs 8 months, P < 0.002). In both groups there was no significant difference in DFS in patients receiving one, two, three or more lines of therapy prior to transplantation. In summary, in patients with poor-risk lymphoma who have responsive disease high-dose therapy may result in durable CRs. Conversely, only a small proportion of patients with HD or NHL with resistant disease achieve CR after autologous stem cell rescue.

Adolescent↗
PubMed1995

Comparative genomic analysis of tumors: detection of DNA losses and amplification.

We demonstrate the use of representational difference analysis for cloning probes that detect DNA loss and amplification in tumors. Using DNA isolated from human tumor cell lines to drive hybridization against matched normal DNA, we were able to identify six genomic regions that are homozygously deleted in cultured cancer cells. When this method was applied in the reverse way, using normal DNA to drive hybridization against tumor cell DNA, we readily isolated probes detecting amplification. Representational difference analysis was also performed on DNAs derived from tumor biopsies, and we thereby discovered a probe detecting very frequent homozygous loss in colon cancer cell lines and located on chromosome 3p.

Animals↗
PubMed1995

Localization in the nervous system of Drosophila melanogaster of a C-terminus anti-peptide antibody to a cloned Drosophila muscarinic acetylcholine receptor.

Localization in the nervous system of Drosophila melanogaster of a cloned Drosophila muscarinic acetylcholine receptor (mAChR) was investigated using a polyclonal antiserum raised against a peptide corresponding to the predicted receptor carboxyl terminal domain. Immunocytochemical studies on fly sections indicated that the product of the Dm1 mAChR gene was localized in the antennal lobes and in other regions of the brain and thoracic nervous system. Intense staining in the glomeruli of the antennal lobes, the region of the nervous system containing terminals of antennal olfactory sensory neurones and mechanosensory neurones, indicates possible roles for this mAChR gene product in the processing of olfactory and mechanosensory signals in the fly. The staining of a discrete group of neurosecretory cells in the pars intercerebralis of the brain indicates a possible new role for this mAChR in the regulation of neurosecretion. Very little staining is detected in the thoracic nervous system.

Animals↗
PubMed1995

Autografting for multiple myeloma: a 5-year experience at a single institution.

Over a 5-year period, we have performed 33 autologous bone marrow or PBPC transplantations for multiple myeloma. Nine patients were in complete remission and 24 in partial remission at time of transplantation. Conditioning regimens were BEM (BCNU, etoposide and melphalan) in 29, busulphan and cyclophosphamide in three and melphalan alone in one. Two patients (6%), died within 3 months of transplant-related mortality, seven (21.3%), died of disease progression at a median follow-up of 11 months (range 4-24). Twenty-four patients (72.7%) are alive at a median follow-up of 15 months (range 4-61). Of nine patients transplanted in CR, four have relapsed and are alive and five remain in CR. Of 24 patients transplanted in PR, nine have died, six remain in PR, eight achieved CR and one has progressive disease. The overall median progression-free survival (PFS) is 31 months (95% CI = 20-42). For patients transplanted in PR the median PFS is 24 months (95% CI = 22-26), the median PFS for patients transplanted in CR has not yet been reached. The median PFS for patients achieving CR pre- or post-transplantation was better than for patients neither achieving CR pre- nor post-transplantation (P = 0.05). The median PFS was also significantly improved for patients requiring only primary therapy, compared to patients needing second-line therapy to achieve CR or stable PR prior to transplantation (31 vs 11 months, P = 0.02).

Adult↗