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Biomedical subjects

M Brooks

Publications and source records attributed to M Brooks.

At least 19 recordsLinked to original sources
PubMed2001

Renal artery stenosis: a disease worth pursuing.

Consider renovascular hypertension (HT) when: Newly diagnosed hypertension presents with features that are atypical of essential hypertension; Resistant hypertension is associated with risk factors for atheroma; or Angiotensin-converting enzyme (ACE) inhibitor or angiotensin-II-receptor antagonist therapy is associated with increasing plasma creatinine levels. Atheromatous renovascular HT can often be managed medically, which includes intensive correction of cardiovascular risk factors. ACE inhibitors are probably second-line antihypertensives for patients with unilateral renal artery stenosis and two kidneys. First-line antihypertensives are diuretics, beta-blockers and calcium-channel blockers. Bilateral renal artery stenosis, or a unilateral stenosis in a patient with only one kidney, is an absolute contraindication to ACE inhibition.

Angiography↗
PubMed2001

Preoperative assessment of hand circulation by means of Doppler ultrasonography and the modified Allen test.

OBJECTIVE: The aims of this study were as follows: (1) to evaluate Doppler ultrasonography in assessing hand collateral circulation; (2) to define the criteria for an abnormal Doppler ultrasonography dynamic test result; and (3) to validate the modified Allen test. METHODS: The hand circulation of 71 patients scheduled for coronary artery bypass grafting was assessed by means of the Allen test and Doppler ultrasonography. The flow in the superficial palmar branch of the radial artery, the ulnar artery, and the dorsal digital thumb artery with and without radial artery compression were recorded. Flow patterns in the superficial palmar branch of the radial artery, the ulnar artery, and the dorsal digital thumb artery with radial artery compression were categorized into 4 groups: (1) no flow; (2) decreased flow; (3) reversed flow; and (4) increased flow. RESULTS: Among the 71 hands, 4 (5.6%) had an abnormal Allen test result (>10 seconds). Seven (10.6%) of 66 superficial palmar branches of the radial artery, 3 (4.2%) of 71 ulnar arteries, and 2 (2.8%) of 71 dorsal digital thumb arteries showed no flow with radial artery compression, as measured by Doppler ultrasonography. There were significant differences among the 4 groups (superficial palmar branch of the radial artery: F = 7.0, P <.001; ulnar artery: F = 13.1, P <.001; and dorsal digital thumb artery: F = 8.4, P <.001) for the Allen test. Pairwise comparisons showed that when subjected to an Allen test, category 1 patients (no flow) had significantly longer recovery times compared with the other groups (P <.02 in all cases) for the superficial palmar branch of the radial artery, the ulnar artery, and the dorsal digital thumb artery. CONCLUSION: Absence of flow in the dorsal digital thumb artery with radial artery compression is considered an absolute contraindication to radial artery harvesting. An increased recovery time with the modified Allen test predicts absence of flow in the dorsal digital thumb artery in Doppler ultrasonographic flow patterns. This demonstrates the validity of the modified Allen test for primary screening.

Aged↗
PubMed1999

Two distinct mutations cause severe hemophilia B in two unrelated canine pedigrees.

The molecular defects causing severe factor IX deficiency were identified in two distinct canine breed-variants. Both defects were associated with an absence of plasma factor IX coagulant activity and antigen. A large deletion mutation was found in 1 breed variant, spanning the entire 5' region of the factor IX gene extending to exon 6. An approximately 5 kb insertion disrupted exon 8 of the second breed-variant. This insertion was associated with alternative splicing between a donor site 5' and acceptor site 3' to the normal exon 8 splice junction, with introduction of a new stop codon. The resultant transcript lacked most of the factor IX catalytic domain and 3' untranslated region. Molecular analyses of canine hemophilia B define an experimental model for study of inhibitor formation and gene therapy strategies, and provide insight into spontaneous mutation mechanisms in the factor IX gene and on the X chromosome of mammalian species.

Animals↗
PubMed1998

Translumbar inferior vena cava access for Hickman line insertion.

The procedure of translumbar inferior vena cava access and Hickman line insertion is described in a patient with acute myeloid leukaemia and thrombosis of the right internal jugular and right innominate vein. This is a useful technique for the interventionist offering a central venous access service.

Acute Disease↗
PubMed1998

Men's views on male hormonal contraception-a survey of the views of attenders at a fitness centre in Bristol, UK.

The last three decades have seen a significant move in Western society away from traditional gender roles. How do these role changes extend to the area of family planning? Family planning researchers and service providers have focused almost exclusively on women. Scientific research is being undertaken to develop a hormonal contraceptive for men. Service providers should be asking the question: How will UK men respond to a reversible hormonal contraceptive method for males? The aim of the study is to begin answering this question. A descriptive survey explored the view of a sample of UK men towards a future, hormonal contraceptive method. Self-administered questionnaires were distributed through convenience sampling to 250 men. The response rate was 46 per cent (115). In terms of preference of contraceptive methods, the 'male pill' ranked third as a first choice and ranked first as the second choice. The results indicate that couples in an established relationship may be the appropriate target group for a 'male pill'. The tablet form was the preferred delivery method for a future male hormonal contraceptive. Perceived side effects were not well tolerated with 71 per cent (81) of respondents not prepared to tolerate any. The majority (94 per cent) expected health monitoring and 38 per cent of men were willing to pay between 5-10 per month. The results indicate a potential uptake of a future 'male pill', with couples in an established relationship as an appropriate target group. However, the study was based on a sample which was small and biased towards middle-class professionals. Further research is needed which covers a wider geographical area representing all social groups and includes women.

Adult↗
PubMed1997

Safety and efficacy outcome of mentor alpha-1 inflatable penile prosthesis implantation for impotence treatment.

PURPOSE: We investigated safety and efficacy outcome pertaining to the Mentor Alpha-1, 3-piece inflatable penile prosthesis for impotence treatment. MATERIALS AND METHODS: A 2-phase, multi-institutional, large scale retrospective study, with independently analyzed medical record (phase I) and questionnaire (phase II) data from consecutive eligible patients of 7 physician investigators was performed from March to October 1993. RESULTS: In phase I there were no morbidities of any type in 394 of the 434 patients (90.8%) (mean age 61 years, range 24 to 88) who underwent Alpha-1 implantation (mean followup 22.2 months, range 0.67 to 44.5). The risk of prosthesis malfunction (fluid leak and auto-inflation) was 2.5%. No cylinder aneurysms were reported. A total of 93.1% of Alpha-1 devices was free from explantation (4.4%) or revision surgery (2.5%) for approximately 2 years from the original implant date. Kaplan-Meier actuarial analyses revealed that cumulative survival of the Alpha-1 prostheses at 12, 24 and 36 months was 98 +/- 1%, 93 +/- 2% and 85 +/- 7% until device malfunction, and 91 +/- 2% 83 +/- 4% and 75 +/- 7% until surgical intervention (revision or explantation). In phase II 89% of the men claimed fulfilled expectations with the Alpha-1 prosthesis as impotence treatment. Satisfaction responses 80% or greater were noted with regard to intercourse ability and confidence, and device rigidity and function. Implantation did not result in greater than 80% satisfaction in partner relationships or feelings (as judged by the patient), social or work confidence, or intercourse frequency. Factors adversely affecting satisfaction included partner feelings of dissatisfaction (as judged by the patient), specific physician investigators and need for explantation/revision surgery. CONCLUSIONS: In 1 of the largest multi-institutional implant outcome studies thus far performed, safety and efficacy data concerning the Alpha-1 contemporary inflatable device were found markedly improved over earlier inflatable prostheses and now compare favorably with historical data from noninflatable rod type devices.

Actuarial Analysis↗
PubMed1996

Severe, recessive von Willebrand's disease in German Wirehaired Pointers.

OBJECTIVE: To characterize the biochemical and genetic basis of a clinically severe form of von Willebrand's disease (vWD) in German Wirehaired Pointers. DESIGN: Case series. SAMPLE POPULATION: Plasma samples from 335 German Wirehaired Pointers (8 clinically affected). PROCEDURE: Plasma samples were evaluated, using an ELISA, to determine von Willebrand factor (vWF) antigen concentration. Additional studies performed on samples from clinically affected dogs included coagulation screening tests, factor VIII coagulant activity assays, and immunoelectrophoresis to determine vWF multimeric composition. RESULTS: Mucosal bleeding and bleeding at sites of cutaneous injury were observed in affected dogs by 6 months old. Plasma vWF antigen concentration was markedly reduced, and there was a lack of high molecular weight vWF multimers; findings compatible with type-II vWD. Inheritance and expression pattern of vWD in this breed was most compatible with that of an autosomal recessive trait. CLINICAL IMPLICATIONS: Von Willebrand's disease should be included in the differential diagnoses of bleeding diatheses in German Wirehaired Pointers, with definitive diagnosis confirmed on the basis of canine-specific vWF assays.

Animals↗
PubMed1996

Plasma von Willebrand factor antigen concentration as a predictor of von Willebrand's disease status in German Wirehaired Pointers.

OBJECTIVE: To evaluate the use of plasma von Willebrand's factor (vWF) concentration as a screening test for inherited von Willebrand's disease (vWD) in German Wirehaired Pointers (GWHP). DESIGN: Prospective study. SAMPLE POPULATION: Plasma samples from 467 GWHP. PROCEDURE: Plasma vWF concentrations were measured as vWF antigen (vWF:Ag), using ELISA, and test values were used to estimate prevalence of vWD in GWHP and predict parental vWD status. Test results of progeny from matings of carrier and noncarrier parents were then compared with the predicted outcome of such matings. RESULTS: 376 (81%) GWHP were classified as vWD noncarriers, 58 (12%) as carriers, and 5 (1%) as affected with vWD. An additional 28 (6%) GWHP could not be classified on the basis of plasma vWF:Ag concentration. The observed outcome of tests of 213 pups was not significantly different from that predicted on the basis of parental vWF:Ag concentration. The predictive value of a positive test result (vWF: Ag% < 50) for identifying vWD carriers was 0.89. CLINICAL IMPLICATIONS: Plasma vWF:Ag concentration was an effective predictor of genetic status for the vWD trait, and for the outcome of matings between carriers and noncarriers of vWD in this study of GWHP.

Animals↗
PubMed1996

Isolation and characterization of canine factor IX.

Canine plasma factor IX was purified to homogeneity by a combination of barium citrate precipitation and three-step column chromatographies of DEAE sepharose, heparin agarose and a monoclonal antifactor IX antibody-linked agarose. Canine factor IX has an apparent molecular size of 61 kDa, which is slightly smaller than that of human factor IX, as determined by denatured polyacrylamide gel electrophoresis. Its amino acid composition, amino-terminal and carboxyterminal amino acid sequences agreed well with those predicted from the reported cDNA. Unlike purified human factor IX, canine factor IX preparation often showed a discrete smaller molecular species (approximately 50 kDa) which was generated by a specific proteolytic cleavage between Arg310 and Val311. When purified canine factor IX was utilized as a standard for enzyme linked immunosorbent assay, the concentration of canine factor IX in the pooled normal dog plasma was determined to be 5.3 micrograms/ml with 11.2% carbohydrate content (or 4.7 micrograms/ml for its polypeptide chain moiety). Concentration of plasma factor IX antigen was measured in six severely affected, unrelated hemophilia B dogs. Four had factor IX antigen of less than 1% of the normal, and two had undetectable levels. The latter two had gross molecular abnormalities in their factor IX genes. Three obligate carrier females had variable but proportionately reduced factor IX antigen and factor IX coagulant activity levels. These results provide a quantitative method for measuring canine factor IX antigen which is a prerequisite for studying hemostasis and development of gene transfer approaches in the canine model of hemophilia B.

Animals↗
PubMed1996

Working as a volunteer nurse/midwife in Pakistan.

The contrast in health and life-style between Pakistan and the UK is very great. Working in a country with one of the highest birth and fertility rates in the world, coupled with poverty and an under-developed health care system stretched the authors initiative and resourcefulness in dealing with difficult situations.

Developing Countries↗
PubMed1995

A subgenomic RNA associated with cherry leafroll virus infections.

Cherry leafroll nepovirus (CLRV) genomic RNA 1 (8 kb) and genomic RNA 2 (7 kb) have 3' polyadenylate tracts and, extending 5' from the polyadenylate, nearly identical sequences of 1.6 kb termed the 3' common region. We observed RNAs 1 and 2 and a third RNA of 1.5 kb in nucleic acid extracts of CLRV-infected Nicotiana tabacum suspension cell protoplasts and Chenopodium quinoa plants, using a hybridization probe complementary to 1 kb of the 3' common region. The third RNA was partially purified by preparative gel electrophoresis and chromatography on an oligodeoxythymidylate column. Analyses of transcripts primed by a complementary oligodeoxyribonucleotide and of cDNA clones revealed that the third RNA corresponds to the 3' 1500 nucleotide residues of RNA 1. Hence we designate the newly characterized RNA as RNA 1A. RNA 1A was not detected as encapsidated RNA in extracts of either protoplasts or C. quinoa plants. The amount of accumulated RNA 1A declined between 24 and 48 hr after inoculation of protoplasts with CLRV virions, although CLRV RNAs 1 and 2 continued to accumulate. Other results were not consistent with cleaved RNA 1 being the origin of RNA 1A. RNA 1A has the properties of a subgenomic RNA, presumably synthesized from negative-sense RNA 1 as template.

Base Sequence↗
PubMed1995

Development of degenerative spondylosis of the lumbar spine after partial discectomy. Comparison of laminotomy, discectomy, and posterolateral discectomy.

STUDY DESIGN: The development of degenerative spondylosis after successful operative decompression of the affected nerve root was prospectively evaluated in a comparative case series of 100 patients with a herniated lumbar nucleus pulposus. OBJECTIVES: The objective of this study was to compare the relative incidence of degenerative spondyloarthrosis after successful posterior laminotomy and discectomy and posterolateral extradural discectomy for decompression of a compromised lumbar nerve root. SUMMARY OF BACKGROUND DATA: The relationship between the radiographic appearance of degenerative spondylosis and prior operative procedures has been controversial and at times contradictory. The posterior operative approach with a partial discectomy has been associated with a significant incidence of postoperative degenerative spondylosis and intraneural and perineural fibrosis, complications that may be minimized, or perhaps even eliminated, with the posterolateral evacuation of the offending intervertebral disc fragment. METHODS: Each patient had: 1) not responded favorably to nonoperative treatment, 2) a persistent radiculopathy, 3) correlative imaging studies with no preoperative spondyloarthrosis and 4) minimum 2-year follow-up. Fifty patients were treated by posterior laminotomy and discectomy and fifty were treated by a posterolateral extradural discectomy. Postoperative spondylosis was graded based on the radiographic presence or absence of osteophytes, the intervertebral disc height, the vertebral body alignment and the facet joint changes. RESULTS: At an average postoperative follow-up of 65 months, the incidence of a one grade increase in degenerative spondylosis was 80% of the laminotomy and discectomy patients as compared to 39% of the posterolateral discectomy patients. CONCLUSIONS: The increased incidence of spondyloarthrosis with the posterior approach suggests that minimally invasive posterolateral extradural procedures should be considered for the decompression of a compromised lumbar nerve root.

Diskectomy↗
PubMed1995

Amylase secretion by cultured porcine parotid cells.

The similarity of porcine and human physiology and the availability of slaughterhouse tissues suggests the use of porcine parotid cells as a model for amylase secretion. A procedure is described for the isolation of porcine parotid cells by collagenase-P/dispase digestion of the tissue. The preparation consisted of individual cells and small aggregates that were maintained in primary culture, during which the cells formed aggregates that firmly attached to the plastic substrate. The amylase content of the cultured cells remained adequate for assay of secretory activity during culture for one week after isolation. Depending upon variations in experimental treatments, the cultured cells secreted approx. 35-65% of cellular amylase in response to a carbachol challenge. The cells were slightly responsive to long exposures to isoproterenol, and were unresponsive to nicotine, elevated extracellular K+ or substance P. Secretion induced by carbachol required extracellular Ca2+, was inhibited by atropine and occurred with a nearly linear response over a 30-min period. The Ca2+ ionophore A23187 was also a potent secretagogue for amylase secretion, producing levels of secretion equal to that induced by carbachol. The ease of preparation and the retention of amylase during primary culture suggests that the preparation will be useful in studies on muscarinic receptor-mediated control of amylase secretion.

Amylases↗
PubMed1995

Aortic distensibility and stiffness index measured by magnetic resonance imaging in patients with Marfan's syndrome.

OBJECTIVES: To use magnetic resonance imaging to measure the elastic properties of the aorta of adults with Marfan's syndrome and to compare these results with those obtained by echocardiography. PATIENTS AND METHODS: 12 patients with Marfan's syndrome and 12 controls matched for age. Transverse luminal areas of the ascending and descending aorta were measured using electrocardiographic gated magnetic resonance imaging. Echocardiography was used to measure the diameter of the ascending aorta and aortic arch in patients with Marfan's syndrome. Blood pressure was measured during both scans. RESULTS: In diastole, transverse luminal areas of the ascending and descending aorta were significantly greater in patients with Marfan's syndrome when measured by magnetic resonance imaging and corrected for body surface area; P < 0.02 and P < 0.05 respectively. Patients with Marfan's syndrome had a higher stiffness index (112.77 v 5.78, P < 0.05) and a lower distensibility (0.0066 v 0.0105, P < 0.05) than controls. Results produced by MRI and echocardiography were not significantly different. CONCLUSIONS: Magnetic resonance imaging gives good quality reproducible images of the ascending and descending aorta. In patients with Marfan's syndrome, aortic distensibility and stiffness index measured by magnetic resonance imaging were abnormal (but did not always relate directly to the size of the aorta.

Adult↗