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Biomedical subjects

S Walker

Publications and source records attributed to S Walker.

At least 127 records · Page 7Linked to original sources
PubMed1999

A comparison of epidural ropivacaine infusion alone and in combination with 1, 2, and 4 microg/mL fentanyl for seventy-two hours of postoperative analgesia after major abdominal surgery.

UNLABELLED: Our aim in this prospective, randomized, double-blinded study was to compare the analgesic effectiveness and side effects of epidural infusions with ropivacaine 2 mg/mL alone (Group R; n = 60) and in combination with fentanyl 1 microg/mL (R1F; n = 59), 2 microg/mL (R2F; n = 62), and 4 microg/mL (R4F; n = 63) for up to 72 h after major abdominal surgery. Effective epidural neural blockade was established before surgery; postoperatively, the infusion rate was titrated to a maximum of 14 mL/h for analgesia. No additional analgesics other than acetaminophen were permitted during the infusion. The median of individual visual analog scale score with coughing were <20 mm for all groups (0 = no pain, 100 = worst pain) and was significantly lower (P < 0.01) for Group R4F at rest and with coughing (compared with Group R). Infusions were discontinued due to inability to control pain in significantly fewer patients in Group R4F (16%) than the other groups (34% to 39%; P < 0.01). For all groups, >90% of patients had no detectable motor block after 24 h. Hypotension, nausea, and pruritus were more common with the larger dose of fentanyl. We conclude that, after major abdominal surgery, an epidural infusion of ropivacaine 2 mg/mL with fentanyl 4 microg/mL provided significantly more effective pain relief over a 3-day period than ropivacaine alone or ropivacaine with lower concentrations of fentanyl. IMPLICATIONS: Postoperative epidural analgesic infusions are widely used, but there is little information regarding optimal strengths of opioid with local anesthetic. In this blinded, prospective study, we compared four different epidural infusion solutions for efficacy and side effects over a clinically useful postoperative period and conclude that an epidural infusion of ropivacaine 2 mg/mL with fentanyl 4 microg/mL was most effective.

Abdomen↗
PubMed1999

A Bayesian semiparametric accelerated failure time model.

A Bayesian semiparametric approach is described for an accelerated failure time model. The error distribution is assigned a Pólya tree prior and the regression parameters a noninformative hierarchical prior. Two cases are considered: the first assumes error terms are exchangeable; the second assumes that error terms are partially exchangeable. A Markov chain Monte Carlo algorithm is described to obtain a predictive distribution for a future observation given both uncensored and censored data.

Algorithms↗
PubMed1999

Initial experience in the extraction of chronically implanted pacemaker leads using the Excimer laser sheath.

OBJECTIVE: To assess the safety and efficiency of the Excimer laser sheath in extracting chronically implanted pacemaker leads. PATIENTS: Eight patients were studied (one female, mean age 62 years, range 34 to 77) with 17 pacemaker leads (five atrial, 10 ventricular, two implantable defibrillator). The mean implantation time was 65 months (range 23 to 188). The indications for lead extraction were chronic infection (7), superior vena cava obstruction (4), lead malfunction (4), and pain (2). METHODS: A prospective analysis of the use of the Excimer laser sheath in extracting chronically implanted pacemaker leads. Laser sheath extraction was undertaken if conventional extraction techniques with simple traction or traction with a locking stylet had failed. If laser sheath extraction was unsuccessful, basket retrieval of the lead from the groin was performed. RESULTS: Complete lead removal was achieved in 16 leads (94%). In one case the electrode tip was left behind without complication. Extraction was achieved with the laser sheath alone in 16 leads. Basket retrieval was required in one case after laser failure. There were no complications. CONCLUSIONS: The Excimer laser sheath appears to be an effective and safe technique for extracting chronically implanted pacemaker leads. It can be used in combination with the currently available techniques for successful lead extraction.

Adult↗
PubMed1999

Stabilisation of medically refractory ventricular arrhythmia by intra-aortic balloon counterpulsation.

OBJECTIVE: To review the efficacy of intra-aortic balloon counterpulsation (IABCP) in medically refractory ventricular arrhythmia. DESIGN: Retrospective analysis of the outcome of patients with ventricular arrhythmia treated with IABCP after transfer between 1992 and 1997. SETTING: Tertiary cardiac referral centre. PATIENTS: 21 patients (mean age 58 years) who underwent IABCP for control of ventricular arrhythmia. All had significant left ventricular impairment (mean ejection fraction 28.6%); 18 had coronary artery disease. RESULTS: Before IABCP, 10 patients had incessant monomorphic ventricular tachycardia and 11 had paroxysmal ventricular tachycardia and/or ventricular fibrillation (VT/VF). IABCP resulted in suppression of ventricular arrhythmia in 18 patients, of whom 13 were weaned from IABCP. After stabilisation of ventricular arrhythmia, 10 patients were maintained on medical treatment alone and one underwent endocardial resection. IABCP was maintained until cardiac transplantation in five patients. One patient had a fatal arrest before discharge and one died from progressive heart failure. IABCP failed to control ventricular arrhythmia in three patients and was subsequently discontinued. A cardiac assist device was employed in one of these until cardiac transplantation; the other two were eventually stabilised on medical treatment. Nineteen patients were discharged from hospital. Overall survival was 95% at mean follow up of 25.7 months. CONCLUSIONS: IABCP can be an effective means of controlling refractory ventricular arrhythmia, allowing time for the institution of more definitive treatment.

Adult↗
PubMed1999

Retrospective comparison of the Amplatz thrombectomy device with modified pulse-spray pharmacomechanical thrombolysis in the treatment of thrombosed hemodialysis access grafts.

PURPOSE: To retrospectively evaluate the Amplatz thrombectomy device (ATD) in the treatment of thrombosed hemodialysis grafts and compare it with modified pulse-spray pharmacomechanical thrombolysis (PPT). MATERIALS AND METHODS: During a 4-month period, 79 patients presented with 126 episodes of graft occlusion. Percutaneous recanalization was performed by using the ATD (n = 57) or the modified PPT technique (n = 69). Evaluation included the technical success, complications, and primary patency rates. RESULTS: Technical success was achieved in 93% (53 to 57) of the cases treated with the ATD and in 96% (66 of 69) of the cases treated with modified PPT (P = .70). Complications occurred in 6% (four of 69) of modified PPT procedures and 16% (nine of 57) of ATD procedures. This difference was not statistically significant (P = .08); however, there were significantly more local complications in the ATD group (P = .04). The primary patency rates at 30, 90, and 180 days were 65% and 65%, 36% and 50%, and 26% and 33% for modified PPT and ATD, respectively. Survival curves were found not to differ significantly (P = .49). CONCLUSION: The ATD and modified PPT were similarly successful in the recanalization of thrombosed hemodialysis access grafts and achieved comparable primary patency rates. The higher rate of local complications and technical difficulties encountered with use of the 8-F ATD limit its usefulness for this indication.

Adult↗
PubMed1999

Calculating the interindividual geometric standard deviation for use in the integrated exposure uptake biokinetic model for lead in children.

The integrated exposure uptake biokinetic (IEUBK) model, recommended for use by the U.S. Environmental Protection Agency at residential Superfund sites to predict potential risks to children from lead exposure and to establish lead remediation levels, requires an interindividual geometric standard deviation (GSDi) as an essential input parameter. The GSDi quantifies the variability of blood lead concentrations for children exposed to similar environmental concentrations of lead. Estimates of potential risks are directly related to the GSDi, and therefore the GSDi directly impacts the scope of remediation at Superfund sites. Site-specific GSDi can be calculated for sites where blood lead and environmental lead have been measured. This paper uses data from blood and environmental lead studies conducted at the Bingham Creek and Sandy, Utah, Superfund sites to calculate GSDi using regression modeling, box modeling, and structural equation modeling. GSDis were calculated using various methods for treating values below the analytical method detection and quantitation limits. Treatment of nonquantifiable blood lead concentrations affected the GSDi more than the statistical method used to calculate the GSDi. For any given treatment, the different statistical methods produced similar GSDis. Because of the uncertainties associated with data in the blood lead studies, we recommend that a range of GSDis be used when analyzing site-specific risks associated with exposure to environmental lead instead of a single estimate. Because the different statistical methods produce similar GSDis, we recommend a simple procedure to calculate site-specific GSDi from a scientifically sound blood and environmental lead study.

Algorithms↗
PubMed1999

Prevalence of disabling conditions among African-American children and youth.

This article reports on the prevalence of disabling conditions among children and youth in the African-American subpopulation. The health status of the African-American population as a whole is discussed as well as the disabling conditions among African-American children and youth specifically. The unique social, economic, and health conditions relative to African-American children and youth are highlighted. Recommendations for future research, policy, and practice are made to alleviate problems surrounding African-American children and their families.

Adolescent↗
PubMed1999

[Simultaneous utilization of an implantable automatic defibrillator in a patient with previously implanted bi-ventricular pacemaker for end-stage heart failure].

We report a case of implantable cardioverter defibrillator (ICD) use after previous biventricular pacemaker insertion for end-stage heart failure. A 75-year-old man with inoperable three-vessel coronary artery disease, permanent atrial fibrillation and end-stage heart failure underwent bi-ventricular pacemaker insertion and His bundle ablation for symptomatic control. NYHA class decreased from class III to II after this procedure. Four months after implant the patient developed paroxysmal sustained, symptomatic ventricular tachycardia. ICD implantation was undertaken. No potentially serious ICD-pacemaker interaction was noted during subsequent follow-up. We conclude that ICD implantation is feasible after previous bi-ventricular pacemaker insertion, without the need to explant the bi-ventricular pacing device.

Aged↗
PubMed1999

Relationship of internalized racism to abdominal obesity and blood pressure in Afro-Caribbean women.

Racism is associated with increased psychosocial stress and blood pressure in blacks. However, little is known of the relationship of racism to other features of insulin resistance syndrome. This study examined the relationship of internalized racism to abdominal obesity and elevated blood pressure in a population of black Caribbean women aged 20-55 years. One hundred thirty-three randomly selected women from the island of Barbados comprised the study sample. Data collected included anthropometric and blood pressure measurements, and information about internalized racism, anxiety, and depression. The stress measures including anxiety, depression, and internalized racism were significantly correlated with waist circumference (r = .25, r = .21, and r = .25). After adjusting for age, education, anxiety, and depression, internalized racism remained significantly correlated with waist circumference. The odds ratio associated with development of abdominal obesity among those with high internalized racism (OR = 2.4 [95% CI, 1.1,5.3]) was significant (P < .05) after adjusting for age, education, and body mass index. Blood pressure was not independently related to internalized racism. Studies comparing black-white differences in diseases for which abdominal obesity is a risk factor (eg, diabetes and cardiovascular disease) should take into account the potential role of internalized racism in defining the differences between ethnic groups.

Abdomen↗
PubMed1998

[Anal gland carcinoma with osteoblastic metastases].

HISTORY AND CLINICALLY FINDINGS: A 52-year-old woman was admitted because of anal pain of 6 weeks duration. Physical examination was unremarkable except for a cherry-sized swelling, painful to pressure, on rectal examination. As the erythrocyte sedimentation rate and C-reactive protein were increased (69/115 and 12.1 mg/dl, respectively) and abscess was diagnosed. Carcinoembryonic antigen was within normal limits. INVESTIGATIONS: At rectoscopy a fluctuating abscess-linked swelling was found at 3 cm and a submucous tumour at 5 cm from the anus. TREATMENT AND COURSE: The abscess was cut open and at the level of the dentate line a submucous adenocarcinoma about 3 cm in diameter was resected. A small residual tumour was removed by abdomino-perineal rectal extirpation. As histologically it was an adenocarcinoma not of colorectal type, without relationship to rectal mucosa but in close contact to the anal glands, and the further course did not indicate a metastasis from another primary tumour, the diagnosis of anal gland adenocarcinoma was established. A local recurrency was resected 6 months later, followed by combined radio- and chemotherapy. A diffuse osteoblastic metastasis was discovered later and the patient died 21 months after diagnosis. CONCLUSION: An osteoblastic metastasis from an anal gland carcinoma, as occurred in this case, has not been previously reported.

Adenocarcinoma↗
PubMed1998

The solution structure of the DNA-binding domain of Skn-1.

Skn-1 is a maternally expressed transcription factor that specifies the fate of certain blastomeres early in the development of Caenorhabditis elegans. It has been reported that the DNA-binding domain is a molten globule and that the structure cannot be defined because there are no long-range nuclear Overhauser effects (NOEs). Working with short Skn domain fragments and using 13C-labeled proteins, we have been able to identify 28 long-range NOEs that establish a tertiary fold for the Skn domain. The internal region of the Skn domain consists of three stable helices and one conformationally labile helix organized into a nascent helix-turn-helix-turn-helix-turn-helix motif. The N and C termini of the Skn domain are unstructured and emerge from the same end of the folded domain. This structure is consistent with biochemical data on binding of the Skn domain to DNA, which shows that the N and C termini bind in the adjacent minor and major grooves from the same face of the DNA helix. The NMR solution structure of the Skn domain should be useful for developing a complete understanding of the DNA recognition event, including any conformational changes that take place upon binding.

Amino Acid Sequence↗
PubMed1998

The diagnosis and initial treatment of asthma in young children in New Zealand and the United Kingdom.

AIMS: To conduct a pilot study to test methodology in ascertaining if there are differences between New Zealand and the UK in the symptom and circumstance set that influences a general practitioner in the initial diagnosis of asthma, and to ascertain the treatment prescribed at the time that the diagnosis is made. METHODS: Questionnaires were mailed to 110 general practitioners in each country. General practitioners from the Otago region in New Zealand and from the Nottingham region in Britain were contacted. A follow-up reminder was sent to all non-responders three weeks after the initial mail out. Questions were asked about the symptoms and signs that were considered important, as well as other influences (e.g., passive smoking) when making a diagnosis of asthma in a child under the age of five years. The doctors were also asked what treatment they prescribed at the time of the actual diagnosis of asthma. RESULTS: British doctors considered night cough (p = 0.05) and cough associated with emotion (p = 0.004) more diagnostic of asthma. New Zealand doctors rated cough associated with temperature change (p = 0.05) as being important and they had a lower threshold in diagnosing asthma with respect to history of similar attacks (p = 0.008) compared to their British counterparts. More New Zealand doctors reported using prophylactic/anti-inflammatory agents as first line therapy (59% vs 28%; p = 0.002). CONCLUSIONS: We conclude that there are only minor differences in general practitioners' diagnostic criteria for asthma in the two countries with reference to this small sample. We believe, however, that differing diagnostic criteria could account for different reported incidences of childhood asthma in some countries. There is need for internationally accepted diagnostic criteria.

Asthma↗
PubMed1998

Mental health. Wait not, want not?

The rise in numbers of young people with mental health problems meant that one trust had a waiting list of 143 patients in this group, some of whom had been waiting for over a year. Only 30 per cent of parents of children on the list responded positively to a letter asking them if they wanted their child to remain on the list, resulting in 100 patients being removed. Of these patients, 10 were re-referred within two years, four of them with more severe symptoms. The average time of treatment was longer than for children who had remained on the list, requiring more clinical resources.

Adolescent↗
PubMed1998

Chemistry and cellular aspects of cationic facial amphiphiles.

A series of compounds containing a bile acid core and a polyamine side chain have been synthesized to evaluate their ability to promote the uptake of DNA into cells. These compounds differ from conventional cationic lipids because they contain a positively charged chain attached to a facial amphiphile rather than to a hydrophobic moiety. Formulations of several of the designed compounds were found to dramatically increase the cellular uptake of both plasmid and oligonucleotide DNA. Moreover, initial experiments have shown that some of the compounds promote plasmid gene expression in various tissues after introduction into animals. These results have provided interesting information about structure-activity relationships as well as clues to the mechanism of action that may lead to further improvements in the design.

Journal Article↗