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Biomedical subjects

C Allen

Publications and source records attributed to C Allen.

At least 55 records · Page 3Linked to original sources
PubMed2001

Setting a local research agenda for women's health: The National Centers of Excellence in Women's Health.

Although women's health research expanded greatly in the past 10 years, significant gaps in knowledge remain. Prioritization and promotion of research will help assure continuing progress in closing such gaps and improving the health of women. Although a comprehensive agenda for the new millennium has been developed at the national level, the process for establishing a local research agenda is not well defined. The purpose of this study was to describe criteria for and barriers to establishing a local research agenda in women's health. A secondary aim was to describe mechanisms for identifying women's health researchers and for facilitating multidisciplinary research. Directors of Research at National Centers of Excellence in Women's Health (CoEs) (n = 18) were surveyed by mail for this information. The results indicate that the local research agenda should emphasize health issues that are prevalent in women, research that is likely to establish treatment, psychosocial/cultural factors, and quality of life issues. The process of setting a research agenda should include input from the communities served as well as from scientists. Critical evaluation of scientific strengths and weaknesses is an essential preliminary step in prioritizing research opportunities in order to implement and evaluate a research agenda in women's health.

Academic Medical Centers↗
PubMed2001

An assessment of need for health visiting in general practice populations.

BACKGROUND: An index of the need for health visiting in general practice populations in the United Kingdom was developed, using routinely held data, to inform decisions about the deployment of health visitors. METHODS: The following indicators of need for health visiting were developed by consensus among health visitors and others: the population aged under 5 years; elective admissions under 5 years; births under 2,500 g; deaths under 65 years; all expressed as rates per 10,000 people registered with general practices in Norfolk. All indicators were compared with the number of health visitors per 10,000 people, obtained by a postal survey of health visitors. The indicators were converted to Z-scores and summed to produce a composite score of need for each general practice. The results were compared with the results of a workload profile using data compiled by health visitors within one Primary Care Group. RESULTS: Health visitors are not allocated according to need at either the practice or Primary Care Group level. The Pearson's correlation coefficient between the allocation suggested by this method and current allocation is 0.37 (p < 0.01). The correlation between this method and the allocation suggested by health visitors' workload profiling in one Primary Care Group was 0.76 (p < 0.01). CONCLUSIONS: Health visitors are currently distributed according to historic patterns rather than need. This paper describes a simple method of determining need at general practice level, which can be used to allocate health visitors equitably.

Adolescent↗
PubMed2001

Reliability of a rating scale for measuring speech intelligibility after pediatric cochlear implantation.

OBJECTIVE: To evaluate the reliability of the Speech Intelligibility Rating scale to monitor the speech intelligibility of deaf children who have received cochlear implants. STUDY DESIGN: A prospective study assessing the speech intelligibility of deaf children with cochlear implants by local and cochlear implant program speech and language therapists. SETTING: Pediatric tertiary referral center for cochlear implantation. PATIENTS AND METHODS: Fifty-four children were each rated by two speech and language therapists, one working with the child locally and the other working with the child at the cochlear implant program. All children were between 1.2 and 10.9 years of age at the time of implantation (median, 4.0 years). The follow-up intervals ranged from before implantation to 9 years after implantation. MAIN OUTCOME MEASURE: Correlation coefficient, intraclass correlation coefficient, and kappa statistics were used to assess the interobserver reliability of the Speech Intelligibility Rating scale. RESULTS: Spearman rank correlation coefficient and intraclass correlation coefficient were 0.82 with high statistical significance (p < 0.00001). Kappa statistical analysis revealed a moderate to substantial agreement between the ratings. This agreement also reached a high statistical significance (overall kappa = 0.53, p < 0.000001). The Speech Intelligibility Rating scale was found to be able to discriminate speech intelligibility among subjects, and the ratings covaried with high consistency. CONCLUSION: The study found a high rate of agreement between observers when they used the Speech Intelligibility Rating scale to assess the speech intelligibility of deaf children after cochlear implantation. Because the scale presents information in a format that is understood by parents, local professionals, and health care purchasers, it will be useful to provide them with accessible information on speech intelligibility outcomes of deaf children who have received cochlear implants.

Child↗
PubMed2001

The persistence of electrostatically seeded endothelial cells lining a small diameter expanded polytetrafluoroethylene vascular graft.

PURPOSE: The purpose of this study was to evaluate the persistence of electrostatically seeded endothelial cells (ECs) lining an expanded polytetrafluorethylene (e-PTFE) graft after one week exposure to in vivo circulation in a canine femoral artery bypass model. This was accomplished by visualizing the PKH 26 (red fluorescent) label placed in the EC membranes prior to the seeding procedure. Furthermore, this study was performed to confirm that the source of the ECs lining the graft were those from the initial inoculum. METHODS: This evaluation consisted of harvesting autologous, canine jugular vein ECs, PKH 26 labeling of the ECs, electrostatic EC seeding the e-PTFE grafts (4mm GORE-TEX, Length=6cm), implanting the grafts (femoral artery model) for one week, and explanting the grafts for light, fluorescent and scanning electron microscopy evaluations of the luminal surface. RESULTS: The unseeded grafts (controls) had a mean fluorescence surface coverage of 6.82 +/- 7.19%, while the EC seeded grafts had a mean of 90.3 +/- 14.3% which is significantly (p <0.001) different from the controls. Overall, the seeding time including the EC harvesting and PKH 26 labeling protocol was approximately 75 min. CONCLUSIONS: The electrostatically seeded ECs persisted after implantation of the graft as demonstrated by the PKH 26 labeling data. The fluorescent data also demonstrated that the neointima formed (EC luminal surface coverage) one week after implantation was in fact derived from the ECs initially seeded as determined by the abundance of the labeled ECs.

Animals↗
PubMed2001

Ralstonia solanacearum needs motility for invasive virulence on tomato.

Ralstonia solanacearum, a widely distributed and economically important plant pathogen, invades the roots of diverse plant hosts from the soil and aggressively colonizes the xylem vessels, causing a lethal wilting known as bacterial wilt disease. By examining bacteria from the xylem vessels of infected plants, we found that R. solanacearum is essentially nonmotile in planta, although it can be highly motile in culture. To determine the role of pathogen motility in this disease, we cloned, characterized, and mutated two genes in the R. solanacearum flagellar biosynthetic pathway. The genes for flagellin, the subunit of the flagellar filament (fliC), and for the flagellar motor switch protein (fliM) were isolated based on their resemblance to these proteins in other bacteria. As is typical for flagellins, the predicted FliC protein had well-conserved N- and C-terminal regions, separated by a divergent central domain. The predicted R. solanacearum FliM closely resembled motor switch proteins from other proteobacteria. Chromosomal mutants lacking fliC or fliM were created by replacing the genes with marked interrupted constructs. Since fliM is embedded in the fliLMNOPQR operon, the aphA cassette was used to make a nonpolar fliM mutation. Both mutants were completely nonmotile on soft agar plates, in minimal broth, and in tomato plants. The fliC mutant lacked flagella altogether; moreover, sheared-cell protein preparations from the fliC mutant lacked a 30-kDa band corresponding to flagellin. The fliM mutant was usually aflagellate, but about 10% of cells had abnormal truncated flagella. In a biologically representative soil-soak inoculation virulence assay, both nonmotile mutants were significantly reduced in the ability to cause disease on tomato plants. However, the fliC mutant had wild-type virulence when it was inoculated directly onto cut tomato petioles, an inoculation method that did not require bacteria to enter the intact host from the soil. These results suggest that swimming motility makes its most important contribution to bacterial wilt virulence in the early stages of host plant invasion and colonization.

Bacterial Proteins↗
PubMed2001

Cryptococcomas distinguished from gliomas with MR spectroscopy: an experimental rat and cell culture study.

PURPOSE: To use magnetic resonance (MR) spectroscopy to characterize clinical isolates of Cryptococcus neoformans and a glioma cell line in culture and in experimental rats. MATERIALS AND METHODS: One- and two-dimensional hydrogen 1 MR spectra were acquired from fungi cultured in vitro (16 isolates of C neoformans, three of Candida albicans, three of Aspergillus fumigatus, three of Saccharomyces cerevisiae) and a C6 glioma cell line. Cerebral biopsy specimens were obtained from healthy rats and animals with experimental infections or gliomas (19 healthy brains, 20 cryptococcomas, and 19 gliomas). Unequivocal signal assignment was performed for cell suspensions and tissue samples by using homo- and heteronuclear two-dimensional correlation spectra. RESULTS: MR spectra of C neoformans and cerebral cryptococcomas--but not of other fungi, healthy brains, or gliomas--were dominated by resonances from the cytosolic disaccharide alpha,alpha-trehalose. This spectral pattern was different from that of gliomas, which was dominated by lipids and an increased choline-creatine ratio, and that of healthy brain. CONCLUSION: A remarkably high concentration of alpha,alpha-trehalose in relation to other metabolites that are visible with MR spectroscopy is diagnostic of C neoformans. Cerebral cryptococcomas are an uncommon but serious manifestation of cryptococcosis in humans. Application of these results to the noninvasive diagnosis of cerebral cryptococcomas would help reduce the risk and expense of unnecessary surgery or biopsy and expedite patient treatment.

Animals↗
PubMed2001

Comparison of preference for rizatriptan 10-mg wafer versus sumatriptan 50-mg tablet in migraine.

Rizatriptan (MAXALT, a registered trademark of Merck & Co. Inc.) is a selective 5-HT(1B/1D) receptor agonist with rapid oral absorption and early onset of action in the acute treatment of migraine. This randomized, open-label, crossover outpatient study assessed the preference of 481 patients for rizatriptan 10-mg rapidly disintegrating tablets versus sumatriptan (IMIGRAN, a registered trademark of GlaxoWellcome PLC) 50-mg tablets in the treatment of a single migraine attack with each therapy. Almost twice as many patients preferred rizatriptan 10-mg rapidly disintegrating tablet to sumatriptan 50-mg tablet (64.3 vs. 35.7%, p < or = 0.001). Faster relief of headache pain was the most important reason for the preference, cited by 46.9% of patients preferring rizatriptan and 43.4% of patients who preferred sumatriptan. Headache relief at 2 h was 75.9% with rizatriptan and 66.6% with sumatriptan (p < or = 0.001), with rizatriptan being superior to sumatriptan within 30 min of dosing. Fifty-five percent of patients were pain free 2 h after rizatriptan, compared with 42.1% treated with sumatriptan (p < or = 0.001), rizatriptan being superior within 1 h of treatment. Forty-one percent of patients taking rizatriptan were pain free at 2 h and had no recurrence or need for additional medication, compared to 32.3% of patients on sumatriptan. Rizatriptan was also superior to sumatriptan in terms of the proportions of patients with no nausea, phonophobia or photophobia, and patients with normal function 2 h after treatment intake (p < 0.05). More patients were (completely, very or somewhat) satisfied 2 h after treatment with rizatriptan (73.3%) than 2 h after treatment with sumatriptan (59.0%) (p < or = 0.001). Additionally, 2 h after the dose, more patients found rizatriptan to be very convenient, convenient or somewhat convenient (87.2%) than they did sumatriptan (76.3%) (p < or = 0.001). Both active treatments were well tolerated. The most common side effects with rizatriptan and sumatriptan were nausea (6.6 and 6.9% of patients, respectively), dizziness (6.1 and 5.8%) and somnolence (7.4 and 6.7%).

Administration, Oral↗
PubMed2001

Use of molecular probes to assess geographic distribution of Pfiesteria species.

We have developed multiple polymerase chain reaction (PCR)-based methods for the detection of Pfiesteria sp. in cultures and environmental samples. More than 2,100 water and sediment samples from estuarine sites of the U.S. Atlantic and gulf coasts were assayed for the presence of Pfiesteria piscicida Steidinger & Burkholder and Pfiesteria shumwayae Glasgow & Burkholder by PCR probing of extracted DNA. Positive results were found in about 3% of samples derived from routine monitoring of coastal waters and about 8% of sediments. The geographic range of both species was the same, ranging from New York to Texas. Pfiesteria spp. are likely common and generally benign inhabitants of coastal areas, but their presence maintains a potential for fish and human health problems.

Animals↗
PubMed2001

Risk factors for frequent and severe hypoglycemia in type 1 diabetes.

OBJECTIVE: To determine the risk of frequent and severe hypoglycemia and the associated demographic and clinical risk factors. RESEARCH DESIGN AND METHODS: Demographic and diabetes self-management factors were measured in 415 subjects followed prospectively for 4-6.5 years of type 1 diabetes duration as participants in a population-based incident cohort. Blood samples were collected up to three times yearly to test glycosylated hemoglobin (GHb) levels. Reports of frequent (2-4 times/week) and severe (lost consciousness) hypoglycemia as well as other diabetes self-management data were collected by questionnaires. RESULTS: Frequent hypoglycemia was common (33 and 35% of participants reported this on the 4- and 6.5-year questionnaires, respectively), whereas severe hypoglycemia occurred much less often. Better glycemic control (odds ratio [OR] 1.3 per 2% decrease in GHb, 95% CI 1.1-1.5) and more frequent self-monitored blood glucose (1.5 per blood glucose check, 1.3-1.7) were independently related to frequent hypoglycemia. The association of frequent hypoglycemia with intensive insulin therapy increased with age. Better glycemic control (1.5 per 2% decrease in GHb, 1.2-2.0) and older age were related to severe hypoglycemic reactions. No sociodemographic factors other than age increased the risk of hypoglycemia. CONCLUSIONS: Frequent hypoglycemia was common in a population representing the full range of glycemic control in the community. Intensive insulin management and blood glucose monitoring independently predicted frequent but not severe hypoglycemia. This information may be useful for updating patients such that minor changes in diabetes management might decrease the daily burden of this condition while maintaining intensive insulin therapy.

Adolescent↗
PubMed2001

Predictors, prodromes and incidence of postpartum depression.

The purpose of this study was to determine the incidence of clinically significant depression occurring between 1 and 4 months postpartum and to investigate whether somatic complaints, subsyndromal depressive symptoms, or birth-related concerns among non-depressed women at 1 month were predictive of postpartum depression. This is a prospective cohort study of 465 women from the Wisconsin Maternity Leave and Health Project (WMLHP). Women who were not depressed at 1 month postpartum were reassessed 3 months later for depression occurring at any time in the interval between 1 and 4 months postpartum. Depression was defined as either meeting the criteria for major depression on the National Institute of Mental Health (NIMH) Diagnostic interview Schedule (DIS) or scoring above 15 on the Center for Epidemiologic Studies Depression Scale (CES-D). Physical symptoms were assessed by an adapted Health Responses Scale. Other measures were developed specifically for the WMLHP. Of 465 women, 27 (5.8%) became clinically depressed between 1 and 4 months postpartum. In a logistic regression analysis, four variables (maternal age, depression during pregnancy, thoughts of death and dying at 1 month postpartum, and difficulty falling asleep at 1 month postpartum) were predictive of depression at 4 months postpartum. Breast-feeding, mode of delivery, family income, parity and mother's education did not predict depression. The existence of subsyndromal depressive symptoms, particularly thoughts of death and dying, may represent a prodromal phase of depression and should alert clinicians to the possibility of future postpartum depression. Women with a history of depression during pregnancy should be monitored for signs of postpartum depression for a minimum of 4 months. Obstetricians are in a unique position during the postpartum check-up to screen women for these predictors of future postpartum depression and possibly to avert the development of a clinically significant depressive episode.

Adult↗
PubMed2001

Postprandial bloating after laparoscopic Nissen fundoplication.

OBJECTIVE: To evaluate the prevalence and possible contributing factors to postprandial bloating in patients having chronic gastroesophageal reflux disease (GERD) before and after laparoscopic Nissen fundoplication. DESIGN: A prospective cohort study. SETTING: A tertiary care teaching hospital. PATIENTS: Five hundred and seventy-eight patients with proven GERD. INTERVENTION: Laparoscopic Nissen fundoplication. OUTCOME MEASURES: Symptom severity scores for postprandial bloating and dysphagia, esophageal motility and 24-hour pH measurement before and at 6 months, 2 years and 5 years after laparoscopic Nissen fundoplication. RESULTS: Of the 598 patients, 436 (73%) reported some postprandial bloating before the procedure. The symptom score for bloating significantly improved after surgery (p < 0.0001). There were no significant differences in the lower esophageal sphincter basal pressures or 24-hour pH scores between those who reported improvement or worsening of their postprandial bloating. At 6 months after surgery, 54% of patients experienced postprandial bloating; of these, 49% reported improvement, 21% reported worsening and 30% reported no change in bloating symptoms compared with the preoperative state. Of the patients who reported worsening of postprandial bloating 6 months after surgery, 86 were reassessed 2 years after surgery and 71% reported improvement of this symptom over this time interval. CONCLUSIONS: Bloating is a common symptom in patients who suffer from chronic GERD. Laparoscopic Nissen fundoplication lessens the severity of this symptom in most patients. In a small subgroup of patients, antireflux surgery may exacerbate the bloating, but this improves over time.

Deglutition Disorders↗
PubMed2000

Noninvasive positive-pressure ventilation: a utilization review of use in a teaching hospital.

BACKGROUND: The use of noninvasive positive-pressure ventilation (NIPPV) for acute respiratory failure (ARF) has become more widespread over the past decade, but its prescription, use and outcomes in the clinical setting remain uncertain. The objective of this study was to review the use of NIPPV for ARF with respect to clinical indications, physician ordering, monitoring strategies and patient outcomes. METHODS: A total of 91 consecutive adult patients admitted between June 1997 and September 1998 to a university-affiliated tertiary care hospital in Hamilton, Ont., who received 95 trials of NIPPV for ARF were included in an observational cohort study. Data abstraction forms were completed in duplicate, then relevant clinical, physiologic, prescribing, monitoring and outcome data were abstracted from the NIPPV registry and hospital records. RESULTS: The most common indications for NIPPV were pulmonary edema (42 of 95 trials [44.2%]) and exacerbation of chronic obstructive pulmonary disease (23 of 95 trials [24.2%]). NIPPV was started primarily in the emergency department (62.1% of trials), however, in terms of total hours of NIPPV the most frequent sites of administration were the intensive care unit (30.9% of total hours) and the clinical teaching unit (20.2% of total hours). NIPPV was stopped in 48.4% of patients because of improvement and in 25.6% because of deterioration necessitating endotracheal intubation. The median time to intubation was 3.0 hours (interquartile range 0.8-12.2 hours). The respirology service was consulted for 28.4% of the patients. Physician orders usually lacked details of NIPPV settings and monitoring methods. We found no significant predictors of the need for endotracheal intubation. The overall death rate was 28.6%. The only independent predictor of death was a decreased level of consciousness (odds ratio 2.9, 95% confidence interval 1.0-8.4). INTERPRETATION: NIPPV was used for ARF of diverse causes in many hospital settings and was started and managed by physicians with various levels of training and experience. The use of this technique outside the critical care setting may be optimized by a multidisciplinary educational practice guideline.

Adult↗
PubMed2000

A theoretical description of microdialysis with mass transport coupled to chemical events.

A random-walk simulation of microdialysis is used to examine how a reaction that consumes analyte in the medium external to the probe affects the extraction and recovery processes. The simulations suggest that such a reaction can promote the extraction process while simultaneously inhibiting the recovery process, which appears to be consistent with recent experimental evidence of asymmetry in the extraction and recovery of the neurotransmitter, dopamine, during brain microdialysis. This suggests that quantitative microdialysis strategies that rely on the extraction fraction as a measure of the probe recovery value, such as the no-net-flux method, will produce an underestimate of the analyte concentration in the external medium when that analyte is consumed by a reaction in the external medium. Furthermore, if experimental conditions arise under which the kinetics of the reaction are changed, then changes in the extraction and recovery processes are likely to occur as well. The implications of these theoretical findings for the quantitative interpretation of in vivo microdialysis results obtained for the neurotransmitter dopamine are examined.

Algorithms↗
PubMed2000

Biomimetic synthesis of lantibiotics.

The lantibiotics are a class of highly posttranslationally modified small peptide antibiotics containing numerous lanthionine and dehydroamino acid residues. We have prepared peptides containing multiple dehydroamino acids and cysteine residues in order to probe the biomimetic synthesis of the lantibiotics from their precursor peptides. A novel synthetic methodology was developed to allow the synthesis of multiple dehydroamino acid containing peptides. Cyclisations were rapid, quantitative and regiospecific. Remarkably the peptide sequences alone appear to contain sufficient information to direct a series of stereo- and regiospecific ring closures. Thus both the two linear peptides for the B and E-rings closed stereoselectively. In the case of the A-ring precursor peptide which contained two dehydroamino acids, cyclisation was again totally regioselective, although not totally stereoselective.

Alanine↗
PubMed2000

Polycaprolactone-b-poly(ethylene oxide) copolymer micelles as a delivery vehicle for dihydrotestosterone.

Block copolymer micelles formed from copolymers of poly(caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) were investigated as a drug delivery vehicle for dihydrotestosterone (DHT). The physical parameters of the PCL-b-PEO micelle-incorporated DHT were measured, including the loading capacity of the micelles for DHT, the apparent partition coefficient of DHT between the micelles and the external medium and the kinetics of the release of DHT from the micelle solution. The MTT survival assay was used to assess the in vitro biocompatibility of PCL-b-PEO micelles in HeLa cell cultures. The biological activity of the micelle-incorporated DHT was evaluated in HeLa cells which had been co-transfected with the expression vectors for the androgen receptor and the MMTV-LUC reporter gene. The PCL-b-PEO micelles were found to have a high loading capacity for DHT and the release profile of the drug from the micelle solution was found to be a slow steady release which continued over a 1-month period. The biological activity of the micelle-incorporated DHT was found to be fully retained.

Dihydrotestosterone↗
PubMed2000

Analysis of PTCH/SMO/SHH pathway genes in medulloblastoma.

Inactivation of the PTCH tumor suppressor gene occurs in a subset of sporadic medulloblastomas, suggesting that alterations in the PTCH pathway may be important in the development of this tumor. In order to address the frequency of genetic alterations affecting genes in this pathway, we used a combination of loss of heterozygosity (LOH) analysis, single-stranded conformational polymorphism (SSCP) analysis, and direct sequencing of DNA samples from sporadic primitive neuroectodermal tumors (PNETs). To identify alterations in the PTCH gene, we performed LOH analysis on 37 tumor DNA samples. Of those with matched constitutional DNA samples, one demonstrated LOH. Of those without matched constitutional DNA, six were homozygous with all markers. All exons of the PTCH gene were sequenced in these seven tumors, and three mutations were found. To identify alterations in the SHH and SMO genes, we analyzed all exons of both genes in 24 tumors with SSCP and sequenced any exons that showed aberrant band patterns. No mutations were found in either SHH or SMO in any tumor. We also identified the following genes as candidate tumor suppressors based on their roles in controlling hh/ptc signaling in Drosophila: EN-1 and EN-2, deletion of which results in a lack of cerebellar development in mice; SMAD family members 1-7, and protein kinase A subunits RIalpha, RIbeta, RIIbeta, Calpha, and Cbeta. Each of these genes was investigated in a panel of 24 matched constitutional and tumor DNA samples. Our search revealed no mutations in any of these genes. Thus, PTCH is the only gene in this complex pathway that is mutated with notable frequency in PNET. Genes Chromosomes Cancer 27:44-51, 2000.

Cerebellar Neoplasms↗