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Biomedical subjects

J Taylor

Publications and source records attributed to J Taylor.

At least 163 records · Page 9Linked to original sources
PubMed1999

Mucosal vaccination with recombinant poxvirus vaccines protects ferrets against symptomatic CDV infection.

Canine distemper virus (CDV) infection of ferrets causes a disease characterized by fever, erythema, conjunctivitis and leukocytopenia, similar clinically to measles except for the fatal neurologic sequelae of CDV. We vaccinated juvenile ferrets twice at 4-week intervals by the intranasal or intraduodenal route with attenuated vaccinia (NYVAC) or canarypox virus (ALVAC) constructs containing the CDV hemagglutinin and fusion genes. Controls were vaccinated with the same vectors expressing rabies glycoprotein. Animals were challenged intranasally 4 weeks after the second vaccination with virulent CDV. Body weights, white blood cell (WBC) counts and temperatures were monitored and ferrets were observed daily for clinical signs of infection. WBCs were assayed for the presence of viral RNA by RT-PCR. Intranasally vaccinated animals survived challenge with no virologic or clinical evidence of infection. Vaccination by the intraduodenal route did not provide complete protection. All control animals developed typical distemper. Ferrets can be effectively protected against distemper by mucosal vaccination with poxvirus vaccines.

Animals↗
PubMed1999

Expression, purification and crystallization of a BH domain from the GTPase regulatory protein associated with focal adhesion kinase.

Signaling by small GTPases is down-regulated by GTPase activating proteins (GAPs) which enhance the rate of GTP hydrolysis. The activity of GAPs specific for Rho GTPases resides in the BH domain, many homologues of which are found in any mammalian genome. One of them was identified in the GTPase regulator associated with focal-adhesion kinase (GRAF). It shares approximately 20% sequence identity with p50RhoGAP. This GAP activates RhoA and Cdc42Hs, but not Rac. In order to dissect the molecular basis of this specificity, a 231-residue-long fragment corresponding to the BH domain of GRAF has been expressed, purified and crystallized. Trigonal crystals, of space group P3(1)21 or P3(2)21, with unit-cell dimensions a = b = 63.5, c = 90.38 A were grown from solutions of PEG 6000. Data to 2.15 A were collected from a flash-frozen sample on an R-AXIS IV imaging-plate detector mounted on a rotating anode X-ray generator.

Amino Acid Sequence↗
PubMed1999

Cardiomyopathy in duchenne, becker, and sarcoglycanopathies: a role for coronary dysfunction?

Dilated cardiomyopathy is a feature of Duchenne and Becker muscular dystrophies and occasionally of sarcoglycanopathies. Its pathogenesis is unknown. Patients with myotonic dystrophy have an impairment of coronary smooth muscle and this could contribute to their cardiomyopathy. We used positron emission tomography (PET) to study myocardial blood flow and coronary vasodilator reserve at baseline and during hyperemia in 7 Duchenne, 8 Becker, and 5 sarcoglycanopathy patients. The study was normal in all Becker patients. In contrast, baseline myocardial blood flow was increased and coronary vasodilator reserve blunted in Duchenne and sarcoglycanopathy patients despite normal hyperemic myocardial blood flow. The reduction of coronary vasodilator reserve was due to an increased baseline myocardial blood flow. In Duchenne dystrophy, but not in sarcoglycanopathies, correction for cardiac workload normalized the coronary vasodilator reserve. In the latter patients, abnormal baseline myocardial blood flow could be due to vascular smooth muscle dysfunction.

Adolescent↗
PubMed1999

Estimating kinetic parameters from dynamic contrast-enhanced T(1)-weighted MRI of a diffusable tracer: standardized quantities and symbols.

We describe a standard set of quantity names and symbols related to the estimation of kinetic parameters from dynamic contrast-enhanced T(1)-weighted magnetic resonance imaging data, using diffusable agents such as gadopentetate dimeglumine (Gd-DTPA). These include a) the volume transfer constant K(trans) (min(-1)); b) the volume of extravascular extracellular space (EES) per unit volume of tissue v(e) (0 < v(e) < 1); and c) the flux rate constant between EES and plasma k(ep) (min(-1)). The rate constant is the ratio of the transfer constant to the EES (k(ep) = K(trans)/v(e)). Under flow-limited conditions K(trans) equals the blood plasma flow per unit volume of tissue; under permeability-limited conditions K(trans) equals the permeability surface area product per unit volume of tissue. We relate these quantities to previously published work from our groups; our future publications will refer to these standardized terms, and we propose that these be adopted as international standards.

Contrast Media↗
PubMed1999

Neurocognitive deficits in medulloblastoma survivors and white matter loss.

Although previous studies have documented a significant risk of intellectual loss after treatment for childhood medulloblastoma (MED), the pathophysiology underlying this process is poorly understood. The purpose of this study was to test the hypotheses that (1) patients treated for MED in childhood have reduced volumes of normal white matter (NWM) related to their treatment with craniospinal irradiation with or without chemotherapy, and (2) deficits in NWM among patients surviving MED can at least partially explain deficits in their intellectual performance. Eighteen pediatric patients previously treated for MED were matched on the basis of age at the time of evaluation to 18 patients previously treated for low-grade posterior fossa tumors with surgery alone (mean difference, 3.7 months). Evaluations were conducted with age-appropriate neurocognitive testing and quantitative magnetic resonance imaging by using a novel automated segmentation and classification algorithm constructed from a hybrid neural network. Patients treated for MED had significantly less NWM (p < 0.01) and significantly lower Full-Scale IQ values than those treated for low-grade tumors (mean, 82.1 vs 92.9). In addition, NWM had a positive and statistically significant association with Full-Scale IQ among the patients treated for MED. We conclude that irradiation- or chemotherapy-induced destruction of NWM can at least partially explain intellectual and academic achievement deficits among MED survivors.

Adolescent↗
PubMed1999

Aberrant expression of CD27 and soluble CD27 (sCD27) in HIV infection and in AIDS-associated lymphoma.

CD27 is a member of the tumor necrosis factor receptor superfamily that is expressed primarily on T cells, as well as on subsets of B cells and NK cells. CD70, which is expressed on activated B and T cells, but not on resting lymphocytes, is a ligand for CD27. Cell surface CD27 can be proteolytically cleaved to produce a 32-kDa soluble CD27 (sCD27) molecule. Elevated levels of sCD27 are seen in a number of disease states and malignancies. Although it has been reported that cerebrospinal fluid sCD27 levels were elevated in people who had AIDS dementia, little is known about CD27 expression in HIV disease. To determine if sCD27 levels were elevated in those with HIV infection, and/or in those with AIDS-associated non-Hodgkin's lymphoma (AIDS-NHL), sCD27 levels were measured in HIV-negative and HIV-positive subjects as well as in people who developed AIDS-NHL. Serum sCD27 levels were seen to be elevated in HIV+ subjects. Furthermore, sCD27 levels were particularly elevated in those subjects who went on to develop AIDS-NHL, with serum sCD27 levels in AIDS-NHL subjects being significantly higher than those in HIV+ subjects who did not develop lymphoma. Most AIDS-NHL cell lines and primary AIDS-NHL tumor specimens expressed both CD27 and its ligand, CD70. The proportion of circulating B cells that expressed cell surface CD27 was substantially reduced in those with HIV infection, and B cells from HIV-infected subjects produced decreased levels of sCD27 in culture. Together, these results indicate that CD27/sCD27 expression is abnormal in HIV infection and suggest that this molecule merits further examination as a potential marker for AIDS-NHL.

Antigens, CD↗
PubMed1999

Regulating plant/insect interactions using CO2 enrichment in model ecosystems.

The greenhouse environment is a challenging artificial ecosystem in which it is possible to study selected plant/insect interaction in a controlled environment. Due to a combination of "direct" and "indirect" effects of CO2 enrichment on plant photosynthesis and plant development, canopy productivity is generally increased. In this paper, we discuss the effects of daytime and nighttime CO2 enrichment protocols on gas exchange of pepper plants (Capsicum annuum L, cv Cubico) grown in controlled environments. In addition, we present the effects of thrips, a common Insect pest, on the photosynthetic and respiratory activity of these plant canopies. Carbon dioxide has diverse effects on the physiology and mortality of insects. However, our data indicate that thrips and whiteflies, at least, are not killed "directly" by CO2 levels used to enhance photosynthesis and plant growth. Together the data suggest that the insect population is affected "indirectly" by CO2 and that the primary effect of CO2 is via its effects on plant metabolism.

Animals↗
PubMed1999

Perindopril for elderly people with chronic heart failure: the PEP-CHF study. The PEP investigators.

BACKGROUND: The prevalence of chronic heart failure (CHF) rises with increasing age, from < 1% in those below 65 years of age to > 5% in those over 65 years of age and is a major cause of morbidity and mortality in older people. Recent European guidelines point to a major deficiency in our knowledge of how to treat diastolic chronic heart failure, and a lack of information on treatment for heart failure in the elderly in general. AIMS: The aims of this trial are to assess the potential benefits of the ACE inhibitor perindopril to treat chronic heart failure in elderly people, in the absence of any major left ventricular systolic dysfunction. SUBJECTS: One thousand people over the age of 70 years will be recruited into this study. Evidence of chronic heart failure will be confirmed by clinical criteria and echocardiography. METHODS: Once a diagnosis of chronic heart failure has been confirmed, the patient will receive either perindopril or placebo in addition to their usual treatment. Death, and unplanned heart failure related hospitalisations, are the primary outcomes. Quality of life, as measured by the Guyatt questionnaire will be assessed at the beginning of the study and at 1 year. Sub-studies of this trial include a 6-min walking test and more detailed evaluation of ventricular function (as assessed by echocardiography). Both parameters will be measured at 8 weeks and 1 year, and analysed against baseline data. Cognitive function in this group of patients will also be evaluated at baseline and 1 year. This trial is due to report in the year 2001.

Aged↗
PubMed1999

A minor salivary gland tumour presenting with dysphagia.

A case is reviewed of a giant benign myoepithelioma of the soft palate presenting in an elderly female patient. Due to the large size of the lesion and its mass effect the patient developed dysphagia with subsequent significant weight loss. The clinico-pathological features of this rare tumour are described and the literature reviewed.

Adenoma, Pleomorphic↗
PubMed1999

Behavioral disinhibition and the development of substance-use disorders: findings from the Minnesota Twin Family Study.

One variant of substance-use disorder is characterized by behavioral disinhibition. In this report, we martial evidence for a model for the development of this variant. We hypothesize that genetic liability for this variant is reflected in a spectrum of risk indicators linked to the inability or unwillingness to inhibit behavioral impulses. Included in this spectrum are personality traits suggesting low constraint, and externalizing psychopathology, including conduct, oppositional defiant, and attention-deficit disorder in children and antisocial personality disorder and behavior in adults. We further hypothesize that these individual differences in behavioral disinhibition are manifestations of underlying central nervous system processes associated with various psychophysiological anomalies, some of which may index genetic risk for substance abuse. Support for the model is derived from the analysis of findings from the Minnesota Twin Family Study, an epidemiological investigation of approximately 2,700 adolescent twins and their parents.

Adolescent↗
PubMed1999

Drink, illicit drugs and unsafe sex in women.

AIMS: To establish the extent and nature of linkages between illicit drug and alcohol use and sexual behaviour in women. PARTICIPANTS AND SETTING: One hundred women attending either a Genitourinary Medicine Clinic or a Family Planning Clinic. DESIGN: Respondents were interviewed using a semi-structured interview schedule covering the effect of drink/illicit drug use on the incidence of sex, on condom use, and on specific sexual activities, and deliberate use of drink/illicit drugs to affect sex. Interviews focused on the last three new male partners, from the beginning of the sexual relationship through its development. Data analysis was primarily qualitative, quantitative analysis was conducted where appropriate. RESULTS: There were few cases in which women reported that consumption of drink/illicit drugs caused them to engage in sexual behaviour which they would not have engaged in if they had not had drink/drugs. Associations between drink and illicit drugs and sexual behaviour were, mainly, either because encounters took place in social situations where drugs or drink were being consumed or because the woman used drink or drugs instrumentally to engage in desired behaviours. There was some evidence to suggest that greater use of drugs and alcohol might be part of a wider pattern of social behaviour including more sexual partners. CONCLUSIONS: The women's self-reported behaviour suggested that illicit drug and alcohol use in itself did not usually result in unsafe or undesired sexual behaviour.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Delayed haemolytic transfusion reaction caused by anti-M antibody in a patient receiving interleukin-2 and interferon for metastatic renal cell cancer.

Anti-M is usually a naturally occurring cold-reactive immunoglobulin M (IgM) antibody, often with an immunoglobulin G (IgG) component, and is seldom implicated in delayed haemolytic transfusion reactions (DHTR). However, cases have been reported. In the majority, a DHTR is not suspected until further blood is requested and a new antibody is detected on pretransfusion testing. We describe the case of a young man receiving therapy with interleukin-2 (IL-2) and interferon-alpha (IFN-alpha) for metastatic renal cell cancer who developed a clinically suspected DHTR that was confirmed serologically to be caused by anti-M, reactive at 37 degrees C. We discuss the possible role of his biochemotherapy in the development of the DHTR.

Adult↗
PubMed1999

Effects of dorsolateral spinal lesions on stretch reflex threshold and stiffness in awake cats.

Measurements of threshold angle and incremental dynamic stiffness (IDS) were derived from triceps surae stretch reflexes, elicited by ramp and hold flexion at the ankle joint of four cats that were tested while awake. Stretch reflexes were assessed from trials that began from different ankle joint start positions or were matched using a post-hoc analysis for initial background force during testing sessions before and following unilateral lesions of the dorsolateral funiculus at levels ranging from T13 to L3. Unilateral lesions of the dorsolateral funiculus (DLF) produced significant ipsilateral decreases in stretch reflex threshold and increases in reflex gain, measured as incremental dynamic stiffness (IDS). ANCOVA testing indicated that the reduction in threshold, but not the increase in IDS, was dependent upon the level of background force. Reflex testing from different start angles demonstrated that DLF lesions diminished the correlation between threshold and IDS. Intravenous infusion of ketamine dose-dependently reduced IDS, compared with testing in the unanaesthetized state. Postoperative reflex testing during infusion of ketamine at 22.2 mg/kg per h, when electromyographic responses were reduced to 24% of control levels, abolished differences in IDS between the ipsilateral and contralateral hindlimbs. These and related observations suggest that the postoperative increase in IDS in awake animals was not due to an increase in passive stiffness.

Anesthetics, Dissociative↗
PubMed1999

Double gloving and a system for identifying glove perforations in maxillofacial trauma surgery.

The treatment of some maxillofacial fractures has an incidence of glove perforation as high as 50%, with over 80% going unnoticed at the time of operation. We investigated double gloving and a glove perforation indication system to ascertain whether the latter offered any additional protection. 1061 gloves used for 113 patients were examined. The outer glove perforation rate was significantly higher than the inner glove (0.48 compared with 0.10, P < 0.0001). There were fewer unnoticed perforations in the glove perforation indication group than the standard surgical glove group (19% compared with 79%, P < 0.0001). The indication system was most effective in wet operating fields. The perforation rate varied with the type of fracture and treatment. Mandibular fractures that were 'hand-held', while bone-plated had a lower mean number of outer glove perforations/operation than fractures treated with temporary intermaxillary fixation (0.43 compared with 4.62, P < 0.0001).

Chi-Square Distribution↗
PubMed1999

A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner.

We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) using a small prototype MR compatible PET scanner (McPET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofrequency interference or susceptibility effects caused by operation of the PET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequency interference from the MR system were investigated. Biological tissue and a T2-weighted spin echo sequence were used to examine susceptibility artefacts due to components of the McPET scanner (scintillator, optical fibres) situated in the MR field of view. A range of commonly used MR pulse sequences was studied while acquiring PET data to look for possible artefacts in either the PET or MR images. Other than a small loss in signal-to-noise using gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is possible to acquire PET and MR images simultaneously, without any significant artefacts or loss in image quality, using our prototype MR compatible PET scanner.

Artifacts↗
PubMed1999

Reduced cytosolic acidification during exercise suggests defective glycolytic activity in skeletal muscle of patients with Becker muscular dystrophy. An in vivo 31P magnetic resonance spectroscopy study.

Becker muscular dystrophy is an X-linked disorder due to mutations in the dystrophin gene, resulting in reduced size and/or content of dystrophin. The functional role of this subsarcolemma protein and the biochemical mechanisms leading to muscle necrosis in Becker muscular dystrophy are still unknown. In particular, the role of a bioenergetic deficit is still controversial. In this study, we used 31p magnetic resonance spectroscopy (31p-MRS) to investigate skeletal muscle mitochondrial and glycolytic ATP production in vivo in 14 Becker muscular dystrophy patients. Skeletal muscle glycogenolytic ATP production, measured during the first minute of exercise, was similar in patients and controls. On the other hand, during later phases of exercise, skeletal muscle in Becker muscular dystrophy patients was less acidic than in controls, the cytosolic pH at the end of exercise being significantly higher in Becker muscular dystrophy patients. The rate of proton efflux from muscle fibres of Becker muscular dystrophy patients was similar to that of controls, pointing to a deficit in glycolytic lactate production as a cause of higher end-exercise cytosolic pH in patients. The maximum rate of mitochondrial ATP production was similar in muscle of Becker muscular dystrophy patients and controls. The results of this in vivo 31P-MRS study are consistent with reduced glucose availability in dystrophin-deficient muscles.

Acids↗
PubMed1999

Episodic retrieval activates the precuneus irrespective of the imagery content of word pair associates. A PET study.

The aim of this study was to evaluate further the role of the precuneus in episodic memory retrieval. The specific hypothesis addressed was that the precuneus is involved in episodic memory retrieval irrespective of the imagery content. Two groups of six right-handed normal male volunteers took part in the study. Each subject underwent six [15O]butanol-PET scans. In each of the six trials, the memory task began with the injection of a bolus of 1500 MBq of [15O]butanol. For Group 1, 12 word pair associates were presented visually, for Group 2 auditorily. The subjects of each group had to learn and retrieve two sets of 12 word pairs each. One set consisted of highly imaginable words and another one of abstract words. Words of both sets were not related semantically, representing 'hard' associations. The presentations of nonsense words served as reference conditions. We demonstrate that the precuneus shows consistent activation during episodic memory retrieval. Precuneus activation occurred in visual and auditory presentation modalities and for both highly imaginable and abstract words. The present study therefore provides further evidence that the precuneus has a specific function in episodic memory retrieval as a multimodal association area.

Acoustic Stimulation↗