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Biomedical subjects

K Taylor

Publications and source records attributed to K Taylor.

At least 91 records · Page 5Linked to original sources
PubMed2000

Safety and efficacy of a steerable temperature monitoring microwave catheter system for ventricular myocardial ablation.

INTRODUCTION: Radiofrequency current delivered during cardiac ablation is limited by a rise in impedance secondary to coagulum formation on the ablation electrode. Microwave antennas continue to deliver energy despite the presence of coagulum; thus, temperature control of the ablation electrode may be even more important for microwave than for radiofrequency ablations to avoid thromboembolic risks. The purpose of this study was to test the safety and efficacy of an ablation system utilizing a feedback control system to maintain a fixed target temperature for creating lesions with multiple applications of microwave energy. METHODS AND RESULTS: Microwave ablation was assessed using an 8.5-French catheter at 2 to 4 sites in 11 dogs. Microwave energy delivery was performed for 60 seconds three times at the same site. Power was regulated using a feedback control mechanism to maintain a target temperature of 75 degrees C. Ambulatory ECG monitoring was performed before and after ablation to assess arrhythmia occurrence. After follow-up, the dogs were euthanized, and lesion dimensions measured after fixation. The mean power applied to achieve the target temperature of 75 degrees C was 9.3+/-44 W. The mean depth of the lesions was 8.8+/-4.2 mm. The mean volume of the lesions was 304+/-240 mm3. Forty-four percent of the lesions were transmural. No endocardial thrombus was found. Ventricular tachycardia was observed acutely but resolved after 1 week. CONCLUSION: Temperature feedback control systems for microwave ablation using a temperature-controlled system is feasible for myocardial ablation and creates uniform and large lesions; however, such large lesions can be acutely proarrhythmic.

Animals↗
PubMed1999

Donor polymorphism of tumor necrosis factor gene: relationship with variable severity of hepatitis C recurrence after liver transplantation.

BACKGROUND: Hepatitis C-related liver failure is the leading indication for liver transplantation worldwide. Although histologic recurrence is identified in the majority of patients, the spectrum of allograft injury is wide. To date, most studies have focused on the contribution of immunosuppression and viral factors. We hypothesized that the allograft plays a significant role in determining timing and severity of hepatitis C virus (HCV) recurrence. The purpose of this analysis was to determine if genetic polymorphisms of the tumor necrosis factor (TNF) locus were associated with the highly variable severity of HCV recurrence. METHODS: Thirty-one HCV-seropositive liver transplant recipients with long-term follow-up were studied. Genomic DNA was extracted from archived donor spleens which corresponded to each patient. We performed polymerase chain reaction amplification, followed by sequencing for two promoter TNF-alpha variants (at positions -238 and -308), and restriction fragment length analysis for four polymorphic loci within the TNF-beta gene (NcoI, TNFc, aa13, and aa26). RESULTS: The relative prevalence of polymorphisms corresponded to distributions previously reported in normal control populations. Twenty-two of 31 (71%) patients received a donor liver homozygous for the wild type allele (TNF1) at the -308 TNF-alpha promoter region. The interval to histologic recurrence was significantly shorter and severity of HCV allograft hepatitis was significantly greater in patients with one or two TNF308.2 alleles. At last follow-up biopsy, 5 of 9 (56%) patients with a TNF308.2 donor liver had evidence of severe histological activity index as compared to 2 of 22 (9%) of patients receiving a donor liver homozygous for the TNF1 allele (P = 0.01). There was no correlation between rejection rates and the presence of any TNF-alpha or TNF-beta alleles. TNF-beta polymorphisms within the donor liver did not correlate with severity of HCV recurrence. CONCLUSIONS: The donor TNF-alpha promoter genotype may influence the inflammatory response to HCV reinfection of the graft and contribute to accelerated graft injury. If the association between this genetic marker (TNF308.2) and disease progression is confirmed, it could improve our understanding of HCV pathogenesis and influence donor selection and patient management.

Alleles↗
PubMed1999

Clustered cadherin genes: a sequence-ready contig for the desmosomal cadherin locus on human chromosome 18.

We describe the assembly of a cosmid and PAC contig of approximately 700 kb on human chromosome 18q12 spanning the DSC and DSG genes coding for the desmocollins and desmogleins. These are members of the cadherin superfamily of calcium-dependent cell adhesion proteins present in the desmosome type of cell junction found especially in epithelial cells. They provide the strong cell-cell adhesion generated by this type of cell junction for which expression of both a desmocollin and a desmoglein is required. In the autoimmune skin diseases pemphigus foliaceous and pemphigus vulgaris (PV), where the autoantigens are, respectively, encoded by the DSG1 and DSG3 genes, severe areas of acantholysis (cell separation), potentially life-threatening in the case of PV, are evident. Dominant mutations in the DSG1 gene causing striate palmoplantar keratoderma result in hyperkeratosis of the skin on the parts of the body where pressure and abrasion are greatest, viz., on the palms and soles. These genes are also candidate tumor suppressor genes in squamous cell carcinomas and other epithelial cancers. We have screened two chromosome 18-specific cosmid libraries by hybridization with previously isolated YAC clones and DSC and DSG cDNAs, and a whole genome PAC library, both by hybridization with the YACs and by screening by PCR using cDNA sequences and YAC end sequence. The contigs were extended by further PCR screens using STSs generated by vectorette walking from the ends of the cosmids and PACs, together with sequence from PAC ends. Despite screening of two libraries, the cosmid contig still had four gaps. The PAC contig filled these gaps and in fact covered the whole locus. The positions of 45 STSs covering the whole of this region are presented. The desmocollin and desmoglein genes, which are about 30-35 kb in size, are quite well separated at approximately 20-30 kb apart and are arranged in two clusters, one DSC cluster and one DSG cluster, which are transcribed outward from the interlocus region. The order of the genes is correlated with the spatial order of gene expression in the developing mouse embryo, and this, and previous transgenic experiments, suggests that long-range genetic elements that coordinate expression of these genes may be present. The complete bacterial clone contig described in this paper is thus a resource not only for future sequencing but also for investigations into the control of expression of these clustered genes.

Bacteriophage P1↗
PubMed1999

Identification and characterization of a zinc finger gene (ZNF213) from 16p13.3.

During our search for the familial Mediterranean fever (FMF) gene, we identified by cDNA selection a 1.2 kb cDNA fragment representing a novel human gene that is expressed in a wide variety of tissues. This gene spans approx. 8.0 kb genomic DNA and has seven exons. Its 3' untranslated region contains a long tandem repeat that gives rise to a polymorphism with two alleles of approx. 1.1 kb and 1.0 kb, with the 1.1 kb allele in strong linkage disequilibrium with FMF in patients of different ethnic backgrounds. However, both genetic and mutational analyses have excluded this gene as the one responsible for FMF. The predicted 424 amino acid protein, designated ZNF213, contains three C2H2 zinc fingers, a Kruppel associated A box and a leucine rich motif (LeR domain/SCAN box), strongly suggestive of a transcription factor.

Amino Acid Sequence↗
PubMed1999

Azimilide pharmacokinetics and pharmacodynamics upon multiple oral dosing.

This study assessed steady-state azimilide pharmacokinetics and pharmacodynamics in 119 healthy male and female volunteers. Parallel groups of 18-40-year-old subjects received doses of 35, 100, 150 or 200 mg day(-1) for up to 14 days, with 1, 2 or 3 days of loading. Another group of > 55-year-old subjects received 100 mg day(-1) with a 3-day loading regimen. There was a slight overshoot of steady-state (24%) after loading, but concentrations decreased to steady-state by day 7. Mean peak steady-state azimilide concentrations ranged from 186 to 1030 ng mL(-1) across the 35-200 mg day(-1) dose range, while mean trough steady-state azimilide concentrations ranged from 108 to 549 ng mL(-1). Azimilide pharmacokinetics were proportional to dose, except for renal clearance, and did not differ between 18-40-year-old and > 55-year-old subjects. Pharmacodynamics did not differ across dose groups. The mean maximum effect (Emax) ranged from 24 to 28% change in QTc from baseline. The concentration needed to attain one half Emax ranged from 432 to 542 ng mL(-1) across dose groups. Equilibration was rapid between blood and the biophase, with equilibration half-lives of less than 1 min.

Administration, Oral↗
PubMed1999

Further evidence for an association between non-insulin-dependent diabetes mellitus and chronic hepatitis C virus infection.

Non-insulin-dependent diabetes mellitus (NIDDM) may be associated with chronic hepatitis C virus (HCV) infection. This was studied further in two parts. First, 1,151 patients with HCV-related cirrhosis and 181 patients with hepatitis B virus (HBV)-related cirrhosis, well matched for age, sex, and severity of cirrhosis, were reviewed retrospectively. The prevalence of diabetes mellitus was higher in HCV-related cirrhosis (23.6%) than in HBV-related cirrhosis (9.4%; odds ratio [OR], 2.78; 95% confidence interval [CI], 1.6-4.79; P =.0002). The prevalence of diabetes mellitus was associated closely with the Child-Pugh score (OR, 3.83; 95% CI, 2. 38-6.17; P <.0001) and increasing age (OR, 1.02; 95% CI, 1.00-1.03; P =.0117). Second, 235 patients with biopsy confirmed chronic HBV or HCV underwent an oral glucose tolerance test. Only 1 of 70 patients with chronic viral hepatitis without cirrhosis was diabetic. However, 31 of 127 patients with HCV-related cirrhosis (24.4%) were diabetic compared with 3 of 38 patients with HBV-related cirrhosis (7.9%, P =.0477). The major variables associated with NIDDM were cirrhosis (OR, 14.39; 95% CI, 1.91-108; P =.0096) and male sex (OR, 4.64; 95% CI, 1. 32-16.18; P =.0161). Fasting insulin levels in 30 patients with HCV-related cirrhosis and diabetes mellitus were elevated significantly, which was consistent with insulin resistance. However, acute insulin responsiveness was reduced in all patients with HCV infection and diabetes suggesting concomitant B-cell dysfunction. This study confirms an association between HCV and NIDDM.

Adult↗
PubMed1999

Breast and cervix cancer screening among multiethnic women: role of age, health, and source of care.

OBJECTIVE: The aim of this study was to evaluate the relationships between age, health status, access to care, and breast and cervical cancer screening among multiethnic elderly and nonelderly women. METHODS: A structured telephone survey of a quota sample of 1,420 New York City women from four Hispanic groups (Columbian, Dominican, Puerto Rican, Ecuadorian) and three black groups (U.S., Caribbean, and Haitian) was performed. Outcome measures included "ever" and "recent" self-reported use of mammography, clinical breast examination (CBE), and Pap smears. Logistic regression models assessed the predictors of screening use. RESULTS: Having a regular source of care significantly predicted all screening use for both elderly and nonelderly, controlling for ethnicity, sociodemographics, health status, access to care, proportion of life in the United States, and cancer attitudes. Elderly women (>/=65 years) were significantly less likely to have ever had (OR = 0.79, 95% CI 0.65-0. 96) and to have recently had (OR = 0.67, 95% CI 0.57-0.79) Pap smears than younger women, controlling for the other variables; being elderly also tended to be an independent predictor of ever and recent mammography and CBE use. Interestingly, there was a trend for health status to act differently in predicting Pap smear use for the two age groups. For younger women, being in poor health increased the odds of Pap smear screening, while for elderly women, being in good health increased the odds of screening. CONCLUSIONS: Elderly women reported being screened less than younger women; interactions between health status and age need further exploration.

Acculturation↗
PubMed1999

Crohn's disease-associated genetic marker is seen in medically unresponsive ulcerative colitis patients and may be associated with pouch-specific complications.

PURPOSE: Genetic markers have been used to define subgroups of patients within the broad categories of Crohn's disease and ulcerative colitis that may differ in clinical course and response to medical therapy. The tumor necrosis factor microsatellite haplotype a2blc2d4e1 has been found previously to be present in 24 percent of patients with Crohn's disease and only 5 percent of patients with ulcerative colitis. This study examined associations between this microsatellite haplotype and the postoperative clinical course of patients with ulcerative colitis undergoing ileal pouch-anal anastomosis. METHODS: As part of a large, controlled, prospective study to correlate genetic markers with clinical phenotypes, tumor necrosis factor microsatellite alleles at five loci (a, b, c, d, and e) were determined from genomic DNA by polymerase chain reaction in 32 patients with a clinical and histopathologic diagnosis of ulcerative colitis who underwent ileal pouch-anal anastomosis for medically unresponsive disease. All patients with ileal pouch-anal anastomosis were also studied prospectively for pouch-specific complications. RESULTS: The tumor necrosis factor haplotype a2blc2d4e1 was present in 11 patients. Median follow-up was 19 months. Thirteen patients had a pouch-specific complication (12 pouchitis and 1 pouch-perineal fistula). Six of 11 patients (55 percent) with the haplotype had a pouch-specific complication compared with 7 of the 21 patients (33 percent) who did not possess this haplotype (P = 0.22). Median time from surgery to pouch-specific complication was eight months. Patients with the haplotype had a median time to pouch-specific complication of three months, whereas patients without the haplotype had a median time of 11 months (P = 0.04). In addition, 36 percent of patients with the haplotype had chronic pouch complications vs. only 10 percent of patients without the haplotype (P = 0.05). CONCLUSION: The Crohn's disease-associated tumor necrosis factor haplotype a2blc2d4e1 may define a subgroup of medically unresponsive patients with ulcerative colitis who are predisposed to a higher incidence of pouch-specific complications after ileal pouch-anal anastomosis.

Adult↗
PubMed1999

Safe mobilization of normal progenitors in advanced chronic myeloid leukemia with intensive chemotherapy and granulocyte-colony stimulating factor.

Twenty-one patients with advanced chronic myeloid leukemia (late chronic phase (n = 8), accelerated phase (n = 11) and blast crisis (n = 2)) were treated with idarubicin, cytarabine, and etoposide followed by G-CSF and subsequent collection of peripheral blood progenitor cells in the early recovery phase. Treatment was reasonably well tolerated with no deaths or intensive care admissions. Despite the advanced phase of disease and heavy pretreatment with cytotoxics and interferon-alfa, 11 of 21 patients (52%) achieved a cytogenetic response. Of the nine major cytogenetic responses (complete (n = 3) and partial (n = 6)), seven achieved adequate progenitor collections for consideration for autologous transplantation. The only predictor of response was disease duration (P = 0.02). With a median follow-up of 1171 days from treatment it appears unlikely that G-CSF contributed to disease progression. Survival post-IcE was predicted by disease stage (P = 0.0001). Intensive chemotherapy followed by G-CSF allowed adequate yields of predominantly Philadelphia chromosome negative progenitor cells to be obtained from one-third of patients with advanced CML.

Adult↗
PubMed1999

Cytokine mRNA profiles in trypanotolerant and trypanosusceptible cattle infected with the protozoan parasite Trypanosoma congolense: protective role for interleukin-4?

African trypanosomes are important pathogens of both humans and livestock. We investigated the association of cytokine responses with disease susceptibility in Trypanosoma congolense-infected cattle. Changes in interleukin (IL)-1beta, IL-2, IL-4, IL-5, IL-6, IL-12 p40, tumor necrosis factor-alpha (TFN-alpha), CD40L, and transforming growth factor-beta (TGF-beta) gene expression were compared in peripheral blood mononuclear cells of infected trypanotolerant N'Dama (Bos taurus) and trypanosusceptible Boran (Bos indicus) cattle. Results revealed that IL-2 transcription was decreased in both breeds of cattle at 21 days after infection. IL-12 p40 mRNA expression was increased in N'Dama cattle at 21 days after infection and at a later time in Boran cattle. The highest IL-4 mRNA expression was observed at 32 days after infection in N'Dama cattle. IL-6 mRNA expression increased in Boran cattle at 11 days after infection and was elevated at 21 and 32 days after infection in both breeds. Transcripts for IL-5 were barely detectable throughout the experimental period in both Boran and N'Dama cattle. Expression of TNF-alpha, IL-1beta, and TGF-beta mRNA did not change notably during the course of infection. In summary, differences in the expression of IL-4 and IL-6 mRNA were identified between the two breeds of cattle during infection with T. congolense, suggesting a possible protective role for IL-4 and a disease-promoting role for IL-6 in bovine trypanosomosis.

Animals↗
PubMed1999

Using self-efficacy to increase physical activity in patients with heart failure.

Increasing self-efficacy is not a state that develops quickly. It is unrealistic to expect that the factors contributing to illness and disability will be modified easily. The home care nurse can positively influence self-efficacy expectations in the heart failure population by creating a supportive environment to perform physical activities (performance mastery), assisting with encouragement and support (verbal persuasion), providing anticipatory guidance and sharing how others perform (vicarious experience), and providing a realistic assessment of a person's abilities (physiologic state). By enhancing self-efficacy, the home care nurse can increase physical activity levels in this population, leading to decreased symptomatology and improved quality of life.

Activities of Daily Living↗
PubMed1999

Linkage of Crohn's disease to the major histocompatibility complex region is detected by multiple non-parametric analyses.

BACKGROUND: There is evidence for genetic susceptibility to Crohn's disease, and a tentative association with tumour necrosis factor (TNF) and HLA class II alleles. AIMS: To examine the potential of genetic linkage between Crohn's disease and the MHC region on chromosome 6p. METHODS: TNF microsatellite markers and, for some families, additional HLA antigens were typed for 323 individuals from 49 Crohn's disease multiplex families to generate informative haplotypes. Non-parametric linkage analysis methods, including sib pair and affected relative pair methods, were used. RESULTS: Increased sharing of haplotypes was observed in affected sib pairs: 92% (48/52) shared one or two haplotypes versus an expected 75% if linkage did not exist (p=0.004). After other affected relative pairs were included, the significance level reached 0.001. The mean proportion of haplotype sharing was increased for both concordant affected (pi=0.60, p=0.002) and unaffected sib pairs (pi=0.58, p=0. 031) compared with the expected value (pi=0.5). In contrast, sharing in discordant sib pairs was significantly decreased (pi=0.42, p=0. 007). Linear regression analysis using all three types of sib pairs yielded a slope of -0.38 at p=0.00003. It seemed that the HLA effect was stronger in non-Jewish families than in Jewish families. CONCLUSIONS: All available analytical methods support linkage of Crohn's disease to the MHC region in these Crohn's disease families. This region is estimated to contribute approximately 10-33% of the total genetic risk to Crohn's disease.

Alleles↗
PubMed1999

Molecular genetic characterisation of frontotemporal dementia on chromosome 3.

We have previously localized a locus causing familial nonspecific dementia to the centromeric region of chromosome 3 in a pedigree from the Jutland area of Denmark. This pedigree shows anticipation. Here we present further analysis of these anticipation data which are suggestive of trinucleotide repeat expansion involvement. We also outline our strategies to clone the mutant gene via its putative associated trinucleotide repeat sequence.

Adult↗