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Biomedical subjects

M Brooks

Publications and source records attributed to M Brooks.

At least 19 recordsLinked to original sources
PubMed2006

Alternative technique for transjugular intrahepatic portosystemic shunt in a young child.

Liver transplantation is safer, more readily available and is increasingly being carried out in younger patients. Therapeutic bridging procedures such as transjugular intrahepatic portosystemic shunt have therefore become more relevant to paediatrics, especially in the group of patients who are too unstable for surgery or in whom a liver graft is not available. We describe a transjugular intrahepatic portosystemic shunt procedure in a 4-year-old child with life-threatening variceal bleeding in whom the conventional procedure had failed. This technique may provide an alternative to conventional transjugular intrahepatic portosystemic shunt in this group.

Child, Preschool↗
PubMed2006

The Valiant thoracic endograft.

Thoracic aortic pathology is common, but conventional surgery carries with it a significant risk of mortality and morbidity due to thoracotomy, extensive surgical dissection, partial left lung collapse, proximal aortic cross-clamping and blood loss necessary for open thoracic aortic replacement. Endovascular techniques have the potential to remove much of this harm. However, endograft delivery to the thoracic aorta brings its own challenges; the graft and delivery system must be conformable to follow the aortic arch, flexible to track through tortuous calcified vessels, of low profile for access through the iliac arteries, and deploy accurately and with minimal force to avoid accidental side branch occlusion. The endoprosthesis must also prove to be durable. This paper reviews current indications for thoracic aortic stent grafts and the properties of an ideal endograft for deployment in the arch and descending aorta. The Medtronic Valiant TM endoprosthesis with Xcelerant TM Delivery System is a third-generation system designed specifically for the treatment of a range of thoracic aortic pathologies, including but not exclusively, aneurysms and dissections. The design of the Valiant endoprosthesis and delivery system are described in detail, and compared to the second-generation Talent system. Our early experience of using Valiant in 28 patients with a range of pathologies is described. The graft achieved an initial technical success in 93% and was easy to position and deploy. Long-term data is now required; the Virtue Registry is a prospective multicenter European registry collecting clinical and health economics data on Valiant in the management of aortic dissections.

Aortic Dissection↗
PubMed2004

An assessment of the Down syndrome antenatal screening policies of East and West Gloucestershire between 1993 and 1999.

This retrospective observational study of registered pregnancies in Gloucestershire between 1 April 1993 and 31 March 1999 compares the impact of different Down syndrome antenatal screening policies on detection and amniocentesis rates. The screening policies in East and West Gloucestershire are based on early second-trimester maternal serum and maternal age screening, respectively. Maternal serum screening can identify a greater proportion of pregnancies affected by Down syndrome than a programme founded on age-based amniocentesis and 20 weeks' ultrasound. In addition, maternal serum screening of women older than 34 approximately halves the number of amniocenteses performed to detect one affected fetus. However, the proportion of pregnant women who have amniocentesis is nearly doubled by offering serum screening to women aged over 24 years. These findings of the impact of established second-trimester screening policies in low-risk populations provides an useful benchmark to compare the performance of screening procedures that will be introduced in the United Kingdom over the next 3 years.

Adult↗
PubMed2002

The Surgical Risk Scale as an improved tool for risk-adjusted analysis in comparative surgical audit.

BACKGROUND: Comparative surgical audit is becoming increasingly important although it is fraught with difficulties due to risk-adjusted analysis. Methods have been proposed to solve this problem and allow meaningful comparison of patient outcome. None has been described without faults, making such comparison flawed or overtly complicated. An alternative risk scoring system incorporating the Confidential Enquiry into Perioperative Deaths (CEPOD) grade, the American Society of Anesthesiologists (ASA) grade and the British United Provident Association (BUPA) operative grade was formulated and assessed. METHODS: This was a prospective audit of 4308 patients admitted under the care of three surgeons between May 1997 and October 1999, creating an initial data set of 3144 procedures with 134 deaths. Each procedure was allocated a score on the basis of the CEPOD, BUPA and ASA grade. The Surgical Risk Scale (SRS) was devised by adding together the values of the three variables, which generated a scale ranging from 3 to 14. Multivariate logistic regression analysis involving the three variables and univariate analysis of the SRS score were undertaken. Receiver-operator characteristic and calibration curves were formulated. This process was validated on another data set (2780 patients) derived from all admissions to the same surgeons between November 1999 and December 2000. RESULTS: Univariate logistic analysis of the SRS score revealed it to be significantly predictive of death (beta = 0.84, P < 0.001); it did not overpredict mortality for low-risk procedures. CONCLUSION: The SRS is easy to use, formulate and interpret, and provides an accurate prediction of death in general surgical patients across the entire risk spectrum.

England↗
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↗