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Biomedical subjects

A Walters

Publications and source records attributed to A Walters.

At least 19 recordsLinked to original sources
PubMed2001

Synthesis of N-alkyl substituted indolocarbazoles as potent inhibitors of human cytomegalovirus replication.

The synthesis and antiviral evaluation of unsymmetrical indolocarbazole derivatives of Arcyriaflavin A, substituted with a range of alkyl groups at the indole nitrogen, is described. Structure-activity relationships in this series against human cytomegalovirus (HCMV) replication in cell culture are reported. Compound 4b was identified as potent inhibitor of HCMV (IC(50)=19 nM), which retained activity against a range of HCMV strains including ganciclovir resistant isolates.

Antiviral Agents↗
PubMed2000

Alternative mechanisms of nonindependent mate choice.

Aspects of the environment, including the social environment, can contribute to intrapopulation variation in mating preferences. One example of the effect of social environment on mate preferences is mate choice copying; however, other types of socially influenced (nonindependent) choice might exist. We develop a list of such alternatives based on possible physiological or psychological mechanisms, evaluate the evidence distinguishing one from another and clarify some controversial aspects of mate choice copying. This framework reveals many ways in which one female's mate choice can influence that of another, and suggests a broader array of hypotheses about the selective forces acting on such mechanisms. Because nonindependent choice can occur in a variety of ways, it could be more important for understanding patterns of mate choice than current theory suggests. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

Rotational Spectrum of CBr by Kinetic Microwave Spectroscopy of 193-nm Photolysis Products of Bromoform.

We have measured the first millimeter-wave spectrum of CBr. The radical was produced by pulsed UV-laser photolysis of bromoform at 193 nm and detected using kinetic spectroscopy. We have significantly improved the rotational and fine structure constants for the ground vibrational state. The hyperfine structure due to the bromine nucleus has been resolved and quadrupole and magnetic hyperfine parameters evaluated for the first time. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Epidemiology of ciprofloxacin-resistant Pseudomonas aeruginosa in a veterans affairs hospital.

This study was performed to identify risk factors for the nosocomial acquisition of ciprofloxacin-resistant Pseudomonas aeruginosa (CRPA) in a Veterans Administration hospital between January 1994, and March 1995. The study was a retrospective comparison of host factors and in-hospital exposures of patients who acquired nosocomially CRPA and ciprofloxacin-sensitive P. aeruginosa (CSPA). Participants included 42 adult patients with nosocomial CRPA acquisition and 52 adult patients with nosocomial CSPA acquisition. Before pseudomonal acquisition, antecedent ciprofloxacin receipt (50% compared with 8%; odds ratio [OR], 12; p = 0.001), the presence of an indwelling airway (36% compared to 17%; OR, 2.6; p = 0.04), and documented antecedent infection (74% compared to 52%; OR, 2.6; p = 0.03) were significantly associated with acquisition of CRPA. On multivariate analysis, antecedent ciprofloxacin receipt (OR, 16.8; p = 0.0001) and presence of an indwelling airway (OR, 10.5; p = 0.009) remain as significant associations. Furthermore, the test of significance confirmed synergy between these two factors. Antecedent ciprofloxacin therapy and indwelling airway act independently and synergistically to promote CRPA acquisition.

Aged↗
PubMed2000

Managing pre-examination stress through remote counselling using a session script from a 'sentinel subject'.

Twenty-five members of a class of 45 medical students preparing for final examinations were voluntary participants in a pre-examination stress-control exercise conducted four weeks before the start of examinations. The students completed short questionnaires before and after reading the typewritten script of a counselling session of a member of their class (the sentinel subject). In the pre-script questionnaires, 50% of the men and 35% of the women reported a high level of stress. On the post-script questionnaire, 68% identified with the subject being counselled. Only four persons (16%) reported a reduction in stress after reading the script and one person recorded an increase in stress. Seventy-two per cent of respondents (40% of students) indicated that they would use counselling services if they were available. The present study suggests that some form of counselling could be usefully included in distance education modules. The provision of counselling services before examinations may prevent failure. The remote approach by sentinel subject script is an inexpensive method of providing such a service.

Adult↗
PubMed1999

Strand displacement amplification and homogeneous real-time detection incorporated in a second-generation DNA probe system, BDProbeTecET.

BACKGROUND: Amplified DNA probes provide powerful tools for the detection of infectious diseases, cancer, and genetic diseases. Commercially available amplification systems suffer from low throughput and require decontamination schemes, significant hands-on time, and specially trained laboratory staff. Our objective was to develop a DNA probe system to overcome these limitations. METHODS: We developed a DNA probe system, the BDProbeTecTMET, based on simultaneous strand displacement amplification and real-time fluorescence detection. The system uses sealed microwells to minimize the release of amplicons to the environment. To avoid the need for specially trained labor, the system uses a simple workflow with predispensed reagent devices; a programmable, expandable-spacing pipettor; and the 96-microwell format. Amplification and detection time was 1 h, with potential throughput up to 564 patient results per shift. We tested 122 total patient specimens obtained from a family practice clinic with the BD ProbeTecET and the Abbott LCx(R) amplified system for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae. RESULTS: Based on reportable results, the BDProbeTecET results for both organisms were 100% sensitive and 100% specific relative to the LCx. CONCLUSIONS: The BDProbeTecET is an easy-to-use, high-throughput, closed amplification system for the detection of nucleic acid from C. trachomatis and N. gonorrhoeae and other organisms.

Chlamydia trachomatis↗
PubMed1998

Orthostatic tremor: an electrophysiological analysis.

Orthostatic tremor (OT) is a clinically defined syndrome of leg tremor while standing. Controversy surrounds whether OT is a distinct syndrome or is an essential tremor (ET) variant. We report two patients with OT. Electrophysiological testing included polymyography, accelerometry, nerve conduction, and evoked potential studies. The effects of various maneuvers and body positions on the tremor were assessed. The findings included rapid (15-17 Hz) lower-extremity tremor burst frequency evoked by standing but not by walking or swaying; rapid upper-extremity burst pattern synchronous with lower-extremity bursts; and failure of electrical stimulation or mental concentration to "reset" the tremor. Additionally, there was the novel finding of accelerometric recordings in the legs revealing the same rapid frequency (16-17 Hz) as the electromyographic tremor bursts. Some prior reports have suggested that OT is related to ET by emphasizing a considerable disparity and variability between the accelerometric tremor frequency and the electromyographic burst frequency. In our patients, however, the rapid (15-17 Hz) accelerometer-recorded tremor synchronous with the electromyographic bursts, and also the clinical improvement with clonazepam but not beta blockers or mysoline, and the lack of a family history of ET provide support that OT is distinct from ET.

Aged↗
PubMed1998

Sub-Millimeter-Wave Spectroscopy of the Ar.H+3 and Ar.D+3 Ionic Complexes.

An investigation of the sub-millimeter-wave spectra of the ionic complexes Ar.H+3 and Ar.D+3 is presented. These complexes were produced in a negative glow electric discharge, in mixtures of argon with either H2 or D2. About 80 new transitions were assigned in the 485-680 GHz frequency range using a sub-millimeter-wave spectrometer built with Russian made backward wave oscillators (BWO) sources. These measurements enabled us to observe the first Ka = 2 transitions for Ar.H+3 and the first Ka = 3 transitions for Ar.D+3. Analyses of the line frequencies were carried out using an IAM-like approach, which accounts for the large amplitude internal rotation motion displayed by both species. Insights into the geometry of the intermediate configuration for this large amplitude motion were gained. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Reproductive performance of lactating dairy cows treated with gonadotrophin-releasing hormone (GnRH) and/or prostaglandin F2a (PGF2a) for synchronization of estrus and ovulation.

The objective of this study was to determine the reproductive performance of lactating dairy cows treated with GnRH and/or PGF2a for synchronization of estrus and ovulation. Between Days 43 and 57 post partum, a total of 374 dairy cows was divided into 4 groups. Cows in Group 1 (n = 62) were treated with 25 mg, i.m. PGF2a on Days 43 and 57; cows in Group 2 (n = 65) were not treated at this time; cows in Group 3 (n = 118) were treated with 100 ug, i.m. GnRH on Day 50, 25 mg, i.m. PGF2a on Day 57, 100 ug, i.m. GnRH on Day 59, and time-inseminated 16 h later; cows in Group 4 (n = 129) were treated with 25 mg, i.m. PGF2a once on Day 57. Cows in Groups 1 and 4 were inseminated at an induced estrus within 7 d after the last PGF2a treatment, and cows in Group 2 were inseminated at a noninduced estrus within a corresponding period of time. Conception rate, estrus detection rate and pregnancy rate were analyzed using logistic regression, and controlled for lactation number, body condition score and time of year. Days from calving to conception were analyzed using the GLM procedures of SAS, and the model included group, body condition score, lactation number, time of year, and their interactions. Cows in Group 3 had a significantly higher pregnancy rate than cows in Groups 1, 2 and 4. Orthogonal contrasts of mean days from calving to conception showed that cows in Group 3 had significantly (P < 0.01) less days from calving to conception than cows in Group 1 and Group 4. There was a significant effect of time of year on pregnancy rate and days from calving to conception, but there was no interaction between time of year and these reproductive characteristics. There was no effect of body condition score and lactation number on the reproductive characteristics evaluated. From the results of this study, it was concluded that better reproductive performance was observed in cows inseminated at a synchronized ovulation than in those inseminated at a synchronized estrous period.

Animals↗
PubMed1995

Quantitative determination of cocaine, cocaethylene (ethylcocaine), and metabolites in plasma and urine by high-performance liquid chromatography.

A sensitive HPLC assay was developed to quantitate the relatively nonpolar compounds cocaine, cocaethylene (ethylcocaine), norcocaine, and norcocaethylene, as well as the relatively polar metabolites benzoylecgonine and benzoylnorecgonine, in rat plasma and urine. The assay in plasma employed two successive liquid-liquid extractions and separate injections onto two different columns (C8 and C18) to separate and quantitate the relatively polar and nonpolar compounds. In urine, the procedure employed a liquid-liquid extraction followed by solid-phase extraction (C18 light-load cartridges) and two separate injections as for plasma. The UV absorbance of the effluent was monitored at 235 nm. Linear standard curves were obtained over the concentration ranges of 25 to 1000 ng/mL and 5 to 250 ng/mL in plasma and urine, respectively. The inter- and intraday coefficients of variation for the assay of all compounds in plasma and urine were < 18% at low concentrations (12.5-100 ng/mL) and < 12% at high concentrations (125-250 ng/mL). There was no degradation of these compounds during the extraction procedure or during 2 months of storage at -20 degrees C. The quantitation limits for the assay of the relatively nonpolar and polar compounds in plasma were 25 (2.5 ng in 0.1 mL) and 50 ng/mL (5 ng in 0.1 mL), respectively. For the assay in urine, the quantitation limits were 5 (2.5 ng in 0.5 mL) and 12.5 ng/mL (6.25 ng in 0.5 mL) for the assay of the relatively nonpolar and polar compounds, respectively. The methods have been applied to quantitate those compounds in rat plasma.

Animals↗
PubMed1994

Sensitive enantiomer-specific high-performance liquid chromatographic analysis of methamphetamine and amphetamine from serum using precolumn fluorescent derivatization.

In order to study the stereoselective disposition of methamphetamine (MAP), a widely abused drug, we have developed a sensitive HPLC assay to separate and quantitate the enantiomers of MAP and amphetamine (AP) in rat serum. Serum samples to which was added aniline sulfate (internal standard) were alkalized with 0.02 M carbonate buffer (pH 10.6) and extracted with ethyl acetate. Following back extraction with hydrochloric acid, neutralization, and reconstitution, the sample was derivatized with (-)-fluorenylethyl chloroformate overnight at room temperature. The derivatized products were separated following injection onto a reversed-phase C18 column. The mobile phase consisted of 0.02 M acetate buffer-acetonitrile-tetrahydrofuran (46:39:15, v/v). The fluorescent intensity of the effluent was monitored at excitation and emission wavelengths of 265 and 330 nm, respectively. The derivatized aniline, R-, S-AP, R- and S-MAP had retention times of 21.0, 22.6, 23.6, 27.7 and 29.0 min, respectively. Linear standard curves were obtained over the concentration range of 5-250 ng/ml. The inter-day and intra-day coefficients of variation for the assay of all four compounds at 12.5, 50.0 and 250 ng/ml were in the range of 2.1-18.6%. The method was applied to quantitate the concentrations of MAP and AP enantiomers in rat serum following a short term intravenous infusion of racemic MAP (15 mg/kg). There were no differences in serum concentrations of MAP enantiomers but the concentrations of S-AP were consistently greater than those of R-AP. These data suggest a stereoselective disposition for the formation and/or elimination of amphetamine.

Acetates↗
PubMed1993

Persistent movement disorders induced by buspirone.

Buspirone, an azospirone compound, is a nonsedative anxiolytic that has achieved wide usage since its introduction in 1987. Although relatively free of side-effects, there have been several instances of dyskinesia and dystonia associated with the use of buspirone. We report two patients with persistent movement disorders that developed after prolonged treatment with the drug. One patient developed a lasting problem of cervical-cranial dystonia and tremors after treatment with buspirone at a dosage of 40 mg/day for several weeks. Another, receiving 30 mg/day for 6 weeks, experienced an exacerbation of preexisting spasmodic torticollis and tardive dyskinesia as well as the onset of involuntary phonations. As shown by these and other examples, buspirone poses the risk for inducing or exacerbating several types of movement disorders.

Antipsychotic Agents↗
PubMed1992

Comparison of Sentinel and Bactec blood culture systems.

AIMS: To evaluate the Sentinel automated blood culture system and to compare its performance with that of Bactec. METHODS: The Sentinel blood culture system was evaluated in three centres. The performance of the system was assessed in comparison with the routine blood culture method used in these centres, the Bactec system. RESULTS: Blood culture sets (n = 2180) consisting of Sentinel aerobic and anaerobic, and Bactec aerobic and anaerobic bottles yielded 218 (10%) clinically important isolates. One hundred and fifty five (71%) of the isolates were detected by both systems; 35 (16%) were detected by Sentinel only; and 28 (13%) by Bactec only. For the duration of the evaluation, the Sentinel system was deliberately configured so that it was impossible to detect positive results during the first 12 hours. The times to positivity after the first 12 hours were similar. Data gathered during and subsequent to the evaluation have been used by the manufacturer to refine the algorithm so that positive results can be detected at a minimum of 2.25 hours. CONCLUSIONS: After a period of familiarization the Sentinel system was considered easy to use. Sentinel is a useful addition to the methods available for the detection of bacteria in blood cultures.

Bacteriological Techniques↗
PubMed1992

Propriospinal myoclonus: a neurophysiologic analysis.

We are reporting a neurophysiologic analysis of two patients presenting with thoracoabdominal spontaneous muscle jerks. Polymyographic recordings showed myoclonic bursts with onset in the upper rectus abdominis or lower intercostal muscles followed by rostral propagation to the upper intercostal and caudal propagation to the abdominal muscles by slowly conducting pathways. Jerk-locked back-averaging did not show time-locked cortical or premovement potentials. Peroneal somatosensory evoked response, C-reflex, and intercostal nerve conduction were normal. These findings suggest a generator for the myoclonus in the midthoracic region of the spinal cord with up and down propagation by slowly conducting pathways, such as propriospinal fibers. This type of spinal myoclonus may thus be termed "propriospinal myoclonus," as suggested by Brown et al.

Aged↗
PubMed1990

Clinically atypical expression of pathologically typical Lewy-body parkinsonism.

Six patients autopsied by the neuropathology service at UMDNJ-Robert Wood Johnson Medical School between 1985 and 1988 had pathologically typical Lewy-body Parkinson's disease (PD). Review of their clinical records revealed that none had clinically typical PD. Atypical clinical features included juvenile onset, retrocollis, strong family history, and absence of tremor, flexed posture, or levodopa response. One patient had dementia without parkinsonism. We conclude that the clinical spectrum of Lewy-body PD is wider than is generally assumed and that the diagnosis of pathologically typical Parkinson's disease cannot be excluded on clinical grounds alone.

Adult↗