Search PubMed⌕ Search

Biomedical subjects

G Richardson

Publications and source records attributed to G Richardson.

At least 73 records · Page 4Linked to original sources
PubMed1998

Right and left ventricular dysfunction in patients with severe pulmonary disease.

OBJECTIVE: To determine the prevalence of right and left ventricular dysfunction in a prescreened population of patients with severe pulmonary disease, and to analyze the relationship between right and left ventricular function. DESIGN: Retrospective record review of 434 patients with severe pulmonary disease. PATIENTS: Patients with end-stage pulmonary disease, including alpha1-antitrypsin deficiency emphysema, COPD, cystic fibrosis (CF), idiopathic pulmonary fibrosis, and pulmonary hypertension (primary and Eisenmenger's syndrome), who were evaluated for lung transplantation between January 1993 and December 1995. MEASUREMENTS: Pulmonary function tests, arterial blood gases, radionuclide ventriculography, two-dimensional transthoracic echocardiography, pulmonary hemodynamics, coronary angiography. RESULTS: Right ventricular dysfunction (right ventricular ejection fraction [RVEF] <45%) was present in 267 patients (66%), but the prevalence was highest (94%) in patients with pulmonary vascular disease. Among the patients with airway or parenchymal lung disease, the prevalence ranged from 59% in COPD to 66% in CF. In contrast, left ventricular dysfunction (left ventricular ejection fraction [LVEF] <45%) was present in only 6.4%, but it, too, was most common in the group with pulmonary hypertension (19.6%). In the groups with parenchymal or airway disease, the prevalence was 3.6%, and there was no statistical difference among the four diagnoses (alpha1-antitrypsin deficiency emphysema; COPD; CF; idiopathic pulmonary fibrosis). LVEF showed a significant correlation with RVEF (r=0.44; p<0.05), and left ventricular dysfunction was associated with the presence of moderate-to-severe tricuspid regurgitation but not with coronary artery disease. In a subset of patients with both right and left ventricular dysfunction who subsequently underwent lung transplantation, RVEF and LVEF increased pari passu after transplantation. CONCLUSION: The prevalence of right ventricular dysfunction is high in patients with end-stage pulmonary disease, but the prevalence of left ventricular dysfunction is relatively low. Left ventricular dysfunction appears to be related to right ventricular dysfunction, perhaps through ventricular interdependence.

Adult↗
PubMed1997

Pattern formation in the basilar papilla: evidence for cell rearrangement.

The avian basilar papilla is composed of hair and supporting cells arranged in a regular pattern in which the hair cells are surrounded and isolated from each other by supporting cell processes. This arrangement of cells, in which the apical borders of hair cells do not contact one another, may be generated by contact-mediated lateral inhibition. Little is known, however, about the way in which hair and supporting cells are organized during development. Whole mounts double-labeled with antibodies to the 275 kDa hair-cell antigen and the tight junction protein cingulin were therefore used to examine the development of cell patterns in the basilar papilla. Hair cells that contact each other at their apical borders are seen during early development, especially on embryonic days (E) 8 and 9, but are no longer observed after E12. Hair and supporting cell patterns were analyzed in three different areas of the papilla at E9 and E12. In two of these regions between E9 and E12, the ratio of supporting cells to hair cells does not change significantly, whereas there is an increase in both the number of supporting cells around each hair cell and the number of hair cells that each supporting cell contacts. In the third region examined, there is a dramatic rise in the number of supporting cells around each hair cell, which although accompanied by a small, significant increase in the ratio of supporting cells to hair cells cannot be accounted for by an increase in supporting cell numbers. These data show that a rearrangement of hair and supporting cells with respect to one another may be a fundamental process underlying the development of a regular pattern in the basilar papilla.

Animals↗
PubMed1997

Isolation of chicken alpha ENaC splice variants from a cochlear cDNA library.

Three splice variants of the alpha subunit of the amiloride-sensitive epithelial sodium channel (alpha ENaC) have been isolated from a chicken cochlear cDNA library. A PCR product, generated from the cochlear library using degenerate primers to regions of homology between the rat alpha ENaC and the degenerin Mec-4, was used as a probe. The three splice variant cDNAs with sizes of 2321, 3399 and 3845 bp correspond to transcripts of 2.5, 3.5 and 3.9 kb as detected by Northern blot analysis. The 3399 bp clone differs from the 2321 clone solely by the addition of 1079 bases in the 3'-non-coding region. Both these cDNAs code for an identical predicted protein of 637 amino acids which has 68% similarity to the rat alpha ENaC, and is probably the chicken homologue of alpha ENaC. The third cDNA of 3845 bp is similar to the 3399 bp clone but includes two exons within the open reading frame. The first of these exons introduces a premature stop codon resulting in a truncated predicted protein of 434 amino acids. Northern blot analysis shows expression of the 2.5 and 3.5 kb transcripts in cochlea and colon, the 2.5 kb transcript in cartilage, whilst the 3.9 kb transcript is only detected in cochlea. No expression is detected in brain, liver, and heart nor, most notably, in lung or kidney.

Alternative Splicing↗
PubMed1997

Efficacy of laser-assisted uvulopalatoplasty.

BACKGROUND AND OBJECTIVE: Laser-assisted uvulopalatoplasty (LAUP) is being used increasingly as a surgical treatment for snoring and obstructive sleep apnea (OSA). There is limited evidence for the success of LAUP in eliminating OSA. This study assesses the efficacy of LAUP in eliminating snoring and OSA and addresses which patients may be the best candidates for LAUP treatment. STUDY DESIGN/MATERIALS AND METHODS: From January 1994 to January 1996, 297 patients were evaluated for snoring, with 190 (64%) exhibiting some degree of OSA documented by a PSG: 41/ 190 (22%) mild OSA; 33/190 (17%) moderate OSA; 85/190 (45%) severe OSA; 31/190 (16%) severity unknown. Ninety patients (90/ 297) have undergone LAUP treatment: 58/90 (64%) with OSA and 32/90 (36%) with snoring only. RESULTS: Our results indicate a significant reduction of snoring in patients without OSA, but diminishing success in patients with increasing degrees of OSA. Additionally, LAUP was not efficacious in treating OSA: pre-op respiratory disturbance index (RDI) of 10.8 vs. post-op RDI of 19.5 for mild OSA (P = 0.14); pre-op RDI of 22.9 vs. post-op RDI of 25.4 for moderate OSA (P = 0.43); pre-op RDI of 56.8 vs. post-op RDI of 46.3 (P < 0.05), which is statistically but not clinically significant (i.e., RDI remained in the severe range). CONCLUSION: We conclude that LAUP is an effective treatment for nonapneic snoring, but does not provide sufficient resolution of OSA, and based on our results, LAUP should be considered as an adjunctive therapy rather than a sole treatment for OSA in most cases.

Adult↗
PubMed1997

Retrieval by other procurement teams provides favorable lung transplantation outcome.

BACKGROUND: During the last 4 years, we have increasingly used lungs retrieved by other procurement teams. We therefore investigated whether the use of those lungs affected the outcome of lung transplantation. METHODS: We analyzed the results of 159 consecutive lung transplantations performed at our institution between July 1, 1992, and December 31, 1995. The transplants were divided into three groups: distant donor lungs retrieved by our team (DB group, n = 68); distant donor lungs retrieved by other teams (DX group, n = 46); and local donor lungs retrieved by our team (LB group, n = 44). One transplantation with a local donor lung retrieved by another team was excluded from the analysis. RESULTS: No significant differences were noted between the three groups in alveolar-arterial oxygen gradient immediately after transplantation (DB group, 359 +/- 18 mm Hg; DX group, 329 +/- 23 mm Hg; LB group, 327 +/- 20 mm Hg) and at 24 hours; days on ventilator; days in the intensive care unit; length of hospital stay; 30-day mortality; and actuarial 1-year survival (DB group, 81%; DX group, 87%; LB group, 89%). CONCLUSIONS: The use of donor lungs retrieved by other teams achieves an equivalently satisfactory outcome after lung transplantation as lungs retrieved by our team.

Adult↗
PubMed1997

Phase I study of paclitaxel and oral etoposide in previously untreated non-small-cell and extensive small-cell lung cancer.

PURPOSE: This phase I study of paclitaxel and oral etoposide was performed to determine the safety of the combination in patients with advanced lung cancer who had received no prior chemotherapy, and to identify a dose for phase II testing. PATIENTS AND METHODS: Patients with locally advanced or metastatic non-small-cell lung cancer (NSCLC) or extensive small-cell lung cancer (SCLC), who had received no prior chemotherapy were treated with intravenous paclitaxel given as a three hour infusion (starting dose 100 mg/m2) and oral etoposide, 100 mg daily for five days. Two schedules of administration were used with the paclitaxel given on day 1 (schedule A) or day 5 (schedule B) of a 21 day cycle. RESULTS: Forty-nine patients were entered on the study, four of whom had SCLC. All patients were evaluable for toxicity. The maximum tolerated dose was paclitaxel 200 mg/m2 on day 1, in combination with oral etoposide 100 mg daily on days 1 to 5 (schedule A). The dose limiting toxicities were mucositis, myalgia, diarrhoea, and paraesthesiae. Using schedule B, myelosuppression, with febrile neutropenia was dose limiting at a paclitaxel dose of 160 mg/m2. Amongst the 45 patients with NSCLC there were three complete and eight partial responses (24%; 95% CI 13% 40%), while there was one complete response in the four patients with SCLC. CONCLUSION: Paclitaxel 200 mg/m2 on day 1, with oral etoposide 100 mg daily on days 1 to 5 can be administered safely, and is the recommended dose for phase II studies.

Administration, Oral↗
PubMed1997

Adult acute leukaemia--a retrospective study of 66 consecutive patients.

BACKGROUND: Advances in therapy and supportive care have improved the outlook for many patients with acute leukaemia, however elderly patients have increased treatment-related toxicity and shorter survival. Most clinical trials have selected patient populations with young median ages and it is therefore difficult to apply results to the general population where the majority of patients presenting with acute leukaemia are over 60 years. There is little information in the literature guiding appropriate treatment of these patients. AIMS: To determine the relationship between age, treatment received, and outcome in patients presenting with acute leukaemia. METHODS: A retrospective analysis was performed on all patients presenting to Prince Henry's Hospital and Monash Medical Centre with acute myeloid leukaemia (AML) or acute lymphocytic leukaemia (ALL) during a five year period. RESULTS: Sixty-six patients (51-AML, 15-ALL) presented with acute leukaemia between March 1989 and April 1994. Median patient age was 63 years; 32% of patients received supportive therapy only; 86% of patients with ALL and 58% of patients with AML commencing remission-induction chemotherapy entered a complete remission. Median survival for patients receiving only supportive therapy was three months. Median survival in patients under 55 years was almost twice as long as patients over 55 years receiving similar treatment (AML-eight vs four months p = 0.023; ALL-3.5 vs seven months p = 0.029). CONCLUSIONS: Median survival for acute leukaemia is inversely proportional to age. Applying results from selected series to elderly patients with acute leukaemia is inappropriate.

Adult↗
PubMed1996

Prevention of infection in a patient with chronic idiopathic neutropenia undergoing coronary bypass surgery with peri-operative G-CSF.

The prevention of postoperative infection complications in a patient with chronic idiopathic neutropenia treated with granulocyte colony stimulating factor (G-CSF) is reported. A 48-year-old woman who presented with chronic idiopathic neutropenia causing life-long recurrent infections, and postoperative suppurative wound infections, presented for elective coronary artery surgery. The patient was successfully treated with G-CSF, resulting in a significantly higher neutrophil count and no infection complications in the peri-operative period. Peri-operative G-CSF therapy in patients with chronic idiopathic neutropenia is effective in increasing the total neutrophil count, and decreasing infection complications.

Chronic Disease↗
PubMed1995

Hair and supporting-cell differentiation during the development of the avian inner ear.

Two monoclonal antibodies and serial section analysis have been used to compare the sites and times at which hair and supporting-cells differentiate in various sensory regions of the chick inner ear during its development. A monoclonal antibody recognising the 275 kD hair-cell antigen, a protein that is specifically associated with the apical surface of hair cells, was used to identify immature hair cells. Another monoclonal antibody, gm-2, which stains the gelatinous membranes of the cochlear duct, sacculus, and utriculus and the epithelial supporting cells of all vestibular structures in the inner ears of early posthatch chicks, was used to detect the onset of supporting-cell differentiation. Although the antigens recognised by the two antibodies are first detected almost simultaneously during the development of each sensory region, their appearance is not always exactly temporally coincident, and their order of appearance, when not coincident, varies between the epithelia but is always the same within any one organ. Also, when the two antigens are first present in any one region, there is not always a very precise overlap in their spatial distribution. These results cannot be explained entirely by a previously proposed model for hair and supporting-cell development in which hair cells differentiate first and prevent undetermined, surrounding cells from becoming hair cells via lateral inhibition. Modified forms of the original model that can accommodate some of these observations are considered and discussed.

Animals↗
PubMed1995

Successful outcome of lung transplantation is not compromised by the use of marginal donor lungs.

Lung transplantation is limited by a shortage of suitable donors. To address this shortage, we have begun using donor lungs that do not meet all of our previous rigorous donor criteria. Of 133 consecutive lung transplants done between June 1991 and March 1994, 89 donors were considered ideal because they satisfied all of the following accepted donor criteria (group I): age younger than 55 years, smoking less than 20 pack-years, arterial oxygen tension greater than 300 mm Hg (using inspired oxygen fraction of 1.0 and positive end-expiratory pressure 5 cm H2O), and chest radiograph negative for infiltrate or trauma (contusion or pneumothorax). Thirty-seven donors failed to satisfy one of these criteria and seven donors failed to satisfy two of them, yielding 51 criteria denoting marginal status in the 44 donors in the marginal group (group II) as follows: age older than 55 years, 2; smoking history 20 or more pack-years, 9; unsatisfactory chest radiograph, 34; and arterial oxygen tension less than 300 mm Hg, 6. Sixty-three single lung transplants were done (group I, 44 versus group II, 19) compared with 70 bilateral sequential transplants (group I, 45 versus group II, 25). In 24 cases in group II, at least one of the lungs actually being implanted contained contusion or infiltrate. Evaluation of recipients from the two groups showed no significant difference in median duration of postoperative mechanical ventilation (3 days in both group I and group II) nor in alveolar-arterial oxygen gradient immediately after transplantation (group I, 304 +/- 14 mm Hg versus group II, 275 +/- 22 mm Hg; p = 0.266) or at 24 hours (group I, 125 +/- 12 mm Hg versus group II, 122 +/- 18 mm Hg; p = 0.933) (all values represent mean plus or minus the standard error). However, cardiopulmonary bypass was required to facilitate second graft insertion in bilateral sequential transplants more often in the marginal group (5 of 25, 20%) than in group I (6 of 45, 13%). There were three deaths within 30 days in group I (operative mortality, 3.4%) and none in group II. Currently, 74 (83.2%) of 89 remain alive in group I compared with 38 (86.4%) of 44 in group II. On the basis of these data, we conclude that successful outcome of lung transplantation can be achieved with the use of marginal donor lungs.

Age Factors↗
PubMed1995

Reflection-on-practice: enhancing student learning.

The writing of a reflective diary is viewed as an effective tool for promoting reflection and learning in students, and for self-assessment and evaluation of a clinical learning experience. This work is a study of 30 undergraduate nurses and their use of reflective diaries during a period of community health care practice. The theoretical basis of the study is based on Schön's work on reflection-in-action. The research tool, developed for the study of nursing practice by Powell, is based on Mezirow's levels of reflectivity. The findings are that, in the sample used, students do reflect on their practice according to Mezirow's levels of reflectivity, but that the highest number of reflections occur at the lower levels of reflectivity (94% of the total number of scores). However, although only 6% of the total number of scores were found at the higher levels of reflectivity, some 22 of the samples of 30 students did attain conceptual and theoretical reflectivity, the highest levels of reflectivity.

Cognition↗
PubMed1995

Immunogenicity of oral poliovirus vaccine administered in mass campaigns versus routine immunization programmes.

Reported are the results of a study to investigate the immunogenicity of oral poliovirus vaccine (OPV) when administered in mass campaigns compared with that following routine immunization programmes. For this purpose, paired sera were collected from a cohort of children before and after a mass vaccination with OPV in Morocco in 1987. Serum samples and information on vaccination status and other confounding factors that could influence antibody responses to OPV were collected. Neutralizing antibody titres to poliovirus types 1, 2 and 3 were determined using a standardized assay. OPV doses administered exclusively during the mass campaign were consistently associated with higher type-specific seroprevalence rates than the same number of doses administered in the routine programme. These findings could not be attributed to differences in confounding factors. Enhanced secondary spread of vaccine virus may have occurred but could not be demonstrated because of limitations in the study design. Mass campaigns appear to be highly effective in raising the dose-related poliovirus type-specific immunity of the population above that achieved by the routine immunization programme. Our findings support the continued use of mass campaigns as an adjunct to routine programmes in order to both enhance and catalyse current efforts to achieve the global eradication of poliomyelitis by the year 2000.

Antibodies, Viral↗