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Biomedical subjects

M Black

Publications and source records attributed to M Black.

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

The efficiency of specialist outreach clinics in general practice: is further evaluation needed?

OBJECTIVES: To assess the need for further evaluation of general practice-based outreach clinics in two specialties using data from a UK pilot study to model their cost-effectiveness. METHODS: A pilot study was undertaken comparing one outreach and one outpatient clinic held by three dermatology specialists and three orthopaedic specialists. Information was collected on waiting times, costs to patients, casemix and resource use. RESULTS: Only dermatology outreach clinic patients experienced significantly shorter waiting times for first appointments than their hospital counterparts. Outreach clinic patients incurred lower costs in attending appointments in either specialty but the differences were not statistically significant. Evidence of a difference in casemix between patients attending outreach and outpatient clinics meant that treatment costs incurred in both types of clinic could not be compared. Outreach clinics in both specialties were significantly more costly in terms of staff, staff travel and associated opportunity costs compared with outpatient clinics. Sensitivity analysis showed that outreach and outpatient clinics had the same marginal cost if the number of patients per outreach clinic increased greatly or attendance fell considerably at outpatient clinics. CONCLUSIONS: This study has found no evidence that outreach clinics in these two specialties are cost-effective in terms of costs and benefits. A more definitive conclusion could only be made if studies estimated other costs and benefits not accounted for in this study. Further research is required to see whether outreach clinics in other specialties or clinics with different configurations to those studied are efficient.

Ambulatory Care Facilities↗
PubMed1997

Specialist outreach clinics in general practice: what do they offer?

BACKGROUND: Specialist outreach clinics in general practice, in which hospital-based specialists hold outpatient clinics in general practitioners' (GPs) surgeries, are one example of a shift in services from secondary to primary care. AIM: To describe specialist outreach clinics held in fundholding general practices in two specialties from the perspective of patients, GPs, and consultants, and to estimate the comparative costs of these outreach clinics and equivalent hospital outpatient clinics. METHOD: Data were collected from single outreach sessions in fundholding practices and single outpatient clinics held by three dermatologists and three orthopaedic surgeons. Patients attending the outreach and outpatient clinics, GPs from practices in which the outreach clinics were held, and the consultants all completed questionnaires. Managers in general practice and hospital finance departments supplied data for the estimation of costs. RESULTS: Initial patient questionnaires were completed by 83 (86%) outreach patients and 81 (75%) outpatients. The specialist outreach clinics sampled provided few opportunities for increased interaction between specialists and GPs. Specialists were concerned about the travelling time resulting from their involvement in outreach clinics. Waiting times for first appointments were shorter in some outreach clinics than in outpatient clinics. However, patients were less concerned about the location of their consultation with the specialist than they were about the interpersonal aspects of the consultation. There was some evidence of a difference in casemix between the dermatology patients seen at outreach and those seen at outpatient clinics, which confounded the comparison of total costs associated with the two types of clinic. However, when treatment and overhead costs were excluded, the marginal cost per patient was greater in outreach clinics than in hospital clinics for both specialties studied. CONCLUSION: The study suggests that a cautious approach should be taken to further development of outreach clinics in the two specialties studied because the benefits of outreach clinics to patients, GPs and consultants may be modest, and their higher cost means that they are unlikely to be cost-effective.

Ambulatory Care Facilities↗
PubMed1996

Study of potency, kinetics of block and toxicity of NMDA receptor antagonists using fura-2.

NMDA receptor antagonists reduced NMDA-triggered increases in [Ca2+]i measured by fura-2 and showed qualitative differences in the potency and kinetics of block. High potency antagonists produced a slow block which allowed an initial increase in [Ca2+]i that was greater than the steady-state level, while compounds with moderate to low potency produced a rapid block that was at steady-state from the first measurement. The more potent antagonists showed the slowest unblocking rates. Using this simple method, novel NMDA antagonists can be screened to ascertain potency, kinetics of block and relative toxicity, prior to animal testing.

Animals↗
PubMed1996

Delivery of DNA-cationic liposome complexes by small-particle aerosol.

Aerosol delivery of gene therapy for treatment of lung diseases allows topical treatment of the airways with DNA concentrations not obtainable by systemic administration. We have investigated delivery of cationic liposomes complexed to plasmid DNA in a small particle aerosol. Plasmid cDNA-DMRIE/DOPE complexes were nebulized using either an Aerotech II or Puritan-Bennett 1600 (PB1600) nebulizer. Reservoir sampling showed that DNA-DMRIE/DOPE complexes were damaged to a significant degree during nebulization, such that activity of transfected gene was diminished. Of the nebulizers analyzed, DNA-DMRIE/DOPE complexes were more stable in the PB1600. The loss of effective transfection by DNA-DMRIE/DOPE, as detected by decreased reporter gene activity in A549 lung cells, was consistent with denaturation of the DMRIE/DOPE. In contrast, nebulized DNA-DOSPA/DOPE complexes retained complete ability to transfect. Adjustments to flow rate and reservoir volume of the PB1600 allowed a longer period of delivery of active DNA-DMRIE/DOPE particles. DNA-DMRIE/DOPE was radiolabeled with Technetium-99m (99mTc), nebulized, and the output captured in either an Andersen Sampler (AS) (Andersen, 1958) cascade impactor particle size analyzer or an all glass impinger. cDNA-cationic lipid complexes were detected in size ranges of 0.4-10 microns, with most particles found between 1-2 microns. Aerosol output was consistent from 0 to 5 min. These results show the feasibility of aerosol delivery of DNA-cationic lipids for the purposes of gene therapy to the lung.

Aerosols↗
PubMed1996

Lung tumours immunoreactive for parathyroid hormone related peptide: analysis of serum calcium levels and tumour type.

Secretion by tumours of parathyroid hormone-related peptide (PTHrP) in quantities sufficient to raise circulating levels results in the syndrome of humoral hypercalcaemia of malignancy (HHM). Since HHM is commonly associated with squamous carcinoma of lung and rarely with adenocarcinoma or lung neuroendocrine tumours, immunopositivity was related to tumour type, to assess whether this difference was due to a low general incidence of PTHrP expression in the latter two groups. Seventy-six of 82 tumours were immunopositive: 22 of 22 squamous carcinomas, 21 of 25 small cell lung carcinomas, 14 of 15 carcinoids, and 19 of 20 adenocarcinomas. These data confirm and extend previous observations on squamous and neuroendocrine tumours but are in contrast with previous findings in adenocarcinoma, which have suggested that only a small proportion of cases express the peptide. They suggest that the differences in incidence of HHM in the various tumour types are due to patterns of secretion, rather than differences in expression of PTHrP. The second aim of this study was therefore to assess whether tumours immunopositive for PTHrP, but not associated with HHM, might secrete PTHrP at levels which might result in more subtle changes in calcium metabolism. Preoperative calcium levels were analysed in a series of 56 patients with immunopositive lung tumours of all types. One small cell carcinoma was associated with hypercalcaemia, but there was no evidence of any other alteration in serum calcium. These data indicate that the majority of tumours expressing PTHrP do not secrete it in amounts sufficient to alter calcium metabolism.

Adenocarcinoma↗
PubMed1996

Comparison of high-resolution endoluminal sonography to video endoscopy in the detection and evaluation of esophageal varices.

High-resolution endoluminal sonography (HRES) was used to image and measure esophageal varices in control subjects and patients with portal hypertension and compared with endoscopic findings. Nine control patients and 68 patients with known cirrhosis or noncirrhotic portal hypertension underwent videotaped HRES and videotaped esophagoscopy (EGD). Two blinded investigators reviewed the videotapes to determine the presence and size of the largest esophageal varix in each patient. The largest varix by HRES was measured with the esophagus at rest at a point where the varix appeared most circular. The largest varix seen on EGD was graded on a 5-point scale. All nine of the control patients were correctly identified by both EGD and HRES as grade I (no varices). Eight of the 10 patients with no varices seen on EGD had varices identified by HRES. The interobserver correlation for HRES was r = .88 and for EGD was r = .79. The correlation between EGD and HRES was r = .50. High resolution endoluminal sonography allows quantitative measurement of variceal size, is a more sensitive and reproducible imaging modality than esophagoscopy for the detection and sizing of esophageal varices. There is poor correlation between monographic measurement and endoscopic grading of esophageal varices. Assessment of esophageal variceal presence and the measurement of variceal size by high resolution endoluminal sonography is an accurate, reproducible method of determining the size of esophageal varices.

Adult↗
PubMed1996

An international investigation of an outbreak of Legionnaires disease among UK and French tourists.

Five cases of legionnaires disease and one death were associated with four members of a tour group from the United Kingdom (UK) and one French tourist who all visited Spain in the spring of 1993. The UK group stayed at four hotels, one of which was also used by the French tourist. Phenotypic and genotypic comparison of isolates of Legionella pneumophila obtained from one of the UK cases and the French patient demonstrated that they were indistinguishable from each other and from environmental isolates obtained from the water supply of the hotel at which all five cases had stayed. A cohort study of the UK tour group was carried out to determine the extent of the outbreak and showed that three further members of the group had respiratory illness but were serologically negative to legionella infection. International participation in this investigation has highlighted the value of a European surveillance scheme and the benefit of microbiological collaboration between legionella reference laboratories in Europe.

Aged↗
PubMed1996

Use of high-resolution endoluminal sonography to measure the radius and wall thickness of esophageal varices.

BACKGROUND: Measurement of variceal wall tension theoretically provides the most accurate method of predicting future variceal bleeding. Using high-resolution endoluminal sonography in 45 patients with known portal hypertension, we measured and correlated the two previously unmeasured variables involved in the calculation of variceal wall tension (radius and wall thickness) by the Laplace equation. METHODS: A 20 MHz 6.2F ultrasound transducer was used to image esophageal varices during standard esophagoscopy. All images were captured on videotape and later reviewed by two blinded investigators. Outer and inner variceal wall circumferences were measured at a cross section of each varix. The radius of each varix and the variceal wall thickness were calculated. The radius of each varix was then correlated with its wall thickness. The interobserver and intraobserver variabilities were measured. RESULTS: The mean variceal radius was .86 +/- .34 cm for the inner radius and 1.48 +/- .41 cm for the outer radius; mean variceal wall thickness was .099 +/- 0.037 cm. Intraobserver and interobserver correlation for the radius was r = .98 and r = .97, respectively. The intraobserver and interobserver correlations for the wall thickness were r = .92 and r = .91, respectively. Variceal radius did not correlate with the wall thickness of the varix. CONCLUSIONS: High-resolution endoluminal sonography provides a method for the accurate measurement of esophageal variceal radius and wall thickness. Variceal radius does not correlate with variceal wall thickness, implying that variceal wall tension cannot be accurately estimated by measurement of variceal size alone. Combining these data with measurements of variceal pressure should allow for the direct determination of wall tension and, subsequently, identification of patients at risk for variceal bleeding.

Adult↗
PubMed1996

Challenges and rewards of involving community in research: an overview of the "Focus on Kids" HIV Risk Reduction Program.

Acquired immunodeficiency syndrome (AIDS) continues to be a significant concern for adolescents, especially in minority populations. There is a scarcity of knowledge of the cultural context of sexual behavior in this age group and the influences that lead to early initiation of sex and unsafe sex. Few efforts targeting young adolescents have been community based, although there has been an increased awareness of the need for such research and intervention programs. Four key processes have been defined in gaining community participation in health education programs: (a) defining the community and reaching the community; (b) recognizing tensions among service, research, and community participation; (c) involving community residents; and (d) considering cultural differences in a community. These processes are used to describe the "Focus on Kids" project, a human immunodeficiency virus (HIV) risk reduction intervention that resulted in significant increases in condom use demonstrated by a randomized controlled trial.

Adolescent↗
PubMed1996

Comparison of in vivo and in vitro haemodynamic function in experimental heart failure: use of echocardiography.

OBJECTIVE: To compare in vivo and in vitro haemodynamic performance in two models of experimental cardiac failure. To validate echocardiography as a means of non-invasive assessment of left ventricular dysfunction in rabbits. METHODS: Cardiac failure was induced by doxorubicin injection (1-1.25 mg.kg-1 twice weekly for 8 weeks (n = 16)) or coronary ligation (n = 12), with 12 controls. Left ventricular diastolic dimension and ejection fraction were assessed in vivo by echocardiography. The doxorubicin-treated and ligation hearts were subdivided by ejection fraction > 0.40 or < or = 0.40 into non-failing and failing groups. Thermodilution cardiac output was measured in vivo at baseline and after a fluid load. Basal cardiac output and peak cardiac output achieved by increased preload were measured in vitro in the working heart mode. RESULTS: The mean ejection fractions in the doxorubicin-treated and ligation groups were significantly (P < 0.001) lower than in controls, but there was wide inter-individual variability ranging from normal to severely impaired function [mean +/- s.d. (range) controls 0.65 +/- 0.03 (0.59-0.72), doxorubicin 0.45 +/- 0.11 (0.30-0.67), ligation 0.42 +/- 0.12 (0.25-0.65)]. Basal and peak cardiac outputs in vivo and in vitro were significantly lower in the doxorubicin and coronary ligation groups than in controls, although there was a wider scatter of values in the pathological groups. Among the doxorubicin and coronary ligation groups, hearts with ejection fractions < or = 0.40 demonstrated significantly impaired haemodynamic function compared with those with ejection fractions > 0.40. There were significant correlations between ejection fraction and all indices of haemodynamic function in vivo and in vitro. CONCLUSIONS: Simple non-invasive measurement of ejection fraction allowed improved characterization of haemodynamic responses in vivo and in vitro. Individual assessment of animals by echocardiography will improve interpretation of cellular or molecular studies in experimental heart failure by relating observed abnormalities to the degree of global cardiac dysfunction.

Animals↗
PubMed1996

A diagnostic molecular marker for zebra mussels (Dreissena polymorpha) and potentially co-occurring bivalves: mitochondrial COI.

We report diagnostic differences in the nucleotide sequences of a 710-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) from the zebra mussel (Dreissena polymorpha) and potentially co-occurring bivalves: the quagga mussel (Dreissena bugensis); the Asiatic clam (Corbicula fluminea), the dark false mussel (Mytilopsis leucophaeata), and the wedge clam (Rangia cuneata). The COI sequence of the deep-water "profunda" phenotype of the quagga mussel was nearly identical to that of shallow-water quagga mussels. Restriction fragment length polymorphisms (RFLPs) in this portion of COI produced species-specific differences in fragment numbers and sizes that could be used as diagnostic markers to distinguish the free-living larvae produced by these bivalves.

Animals↗
PubMed1995

Migration of coordinated cell clusters in mesenchymal and epithelial cancer explants in vitro.

The invasion and migration occurring in primary neoplastic tissue explants were studied by using a three-dimensional collagen matrix model, subsequent time-lapse videomicroscopy, and computer-assisted cell tracking. We show that not only single cells but groups of clustered cells comprising 5 to more than 100 cells detach from the primary tumor lesion and migrate within the adjacent extracellular matrix. These clusters were highly polarized, resulting in a high directional persistence of migration. Locomoting cell clusters were observed in primary cultures from invasive oral squamous cell carcinomas (6 of 9), ductal breast carcinomas (2 of 3), and rhabdomyosarcoma (1 of 1), whereas normal oral mucosa (0 of 4) was cell cluster negative. Thus, locomoting cell clusters could be a novel and potentially important mechanism of cancer cell invasion and metastasis.

Carcinoma, Ductal, Breast↗