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Biomedical subjects

J Hawkins

Publications and source records attributed to J Hawkins.

At least 37 records · Page 2Linked to original sources
PubMed1995

The effect of inhomogeneous sample susceptibility on measured diffusion anisotropy using NMR imaging.

Water diffusion measurements in white matter of freshly excised pig spinal cord and in parenchyma of fresh celery (excluding the fibers along the edge of the stalk) were performed using NMR at 200 MHz. In white matter of pig spinal cord, the measured diffusion coefficient is anisotropic and independent of sample orientation with respect to the magnetic field. In celery parenchyma, diffusion is isotropic and independent of orientation in the magnetic field when using a diffusion sequence that gives results independent of self-induced magnetic-field gradients. However, when the standard diffusion pulse sequence that gives results dependent upon self-induced magnetic-field gradients is used, diffusion in celery appears isotropic when the stalk is oriented parallel to the magnetic field but anisotropic when oriented perpendicular. Susceptibility variations leading to anisotropic self-induced magnetic-field gradients approximately 3 kHz/cm in magnitude when the celery is oriented perpendicular to the magnetic field can explain this apparent anisotropic diffusion. A study of the apparent diffusion coefficient (ADC) in celery as a function of diffusion times ranging from 8 to 22 ms indicates that the motion is at most only slightly restricted. Therefore, although the effect is not seen in all types of samples, one must be aware that self-induced gradients may affect the ADC and may cause isotropic diffusion to appear anisotropic. In addition, NMR experiments that change diffusion-sensitizing gradient timings to study restricted diffusion change the effects of the self-induced gradients as well as the effect of barriers on the ADC, complicating interpretation.

Algorithms↗
PubMed1995

Apathy: a treatable syndrome.

Apathy occurs frequently in neuropsychiatric disorders both as a symptom of other syndromes and as a syndrome per se. Histories are presented of patients with a syndrome of apathy who showed clinically significant, sustained benefit from pharmacological treatment. Etiologies included non-Alzheimer's frontal lobe dementia, cerebral infarction, intracranial hemorrhage, alcoholism, and traumatic brain injury. Agents included amantadine, amphetamine, bromocriptine, bupropion, methylphenidate, and selegiline. These histories support the suggestion that apathy is a discriminable dimension of behavior having its own pathophysiology and implications for psychiatric care. They raise the possibility of treatment for many patients previously thought untreatable. Studying the treatment of apathy may contribute to the clinical care and scientific understanding of neuropsychiatric disorders throughout the life span.

Adult↗
PubMed1994

Prevention of Travelers' Diarrhea: Ciprofloxacin versus Trimethoprim/Sulfamethoxazole in Adult Volunteers Working in Latin America and the Caribbean.

The objective of the study was to compare the safety and efficacy of three treatment protocols for the prevention of travelers' diarrhea: once-daily ciprofloxacin versus trimethoprim/sulfamethoxazole (TMP/SMZ) once daily versus placebo for the prevention of travelers' diarrhea. The study population was comprised of participants in 2-week medical-missions projects based in Latin America and the Caribbean. The diverse age group and varied study sites closely resembles the population of travelers who seek pretravel advice from physicians. A prospective, randomized, double-blind, placebo-controlled comparison was designed. Subjects who developed diarrhea, defined as three stools in 8 hours plus one or more signs of an enteric infection, were considered prophylaxis failures. Stool specimens were collected and examined for the presence of enteric pathogens. DNA probes were used to determine the presence of diarrheagenic E. coli. Bacterial colony blots were used. Adverse events were recorded by participants in a diary. Three hundred and forty-four subjects were entered in the study, of which two hundred and seventy-eight subjects met the criteria for the efficacy and safety review. Subjects were randomly assigned to receive ciprofloxacin (500 mg), TMP/SMZ (160/800 mg), or placebo. Five of the 99 (5%) subjects taking ciprofloxacin, 14 of the 87 (16%) taking TMP/SMZ, and 30 of the 92 (33%) taking placebo experienced diarrhea. Bacterial pathogens were identified more commonly in the TMP/SMZ and placebo groups than in the ciprofloxacin-treated group. The incidence of adverse reactions was 9.0%, 14.8%, and 7.5% for ciprofloxacin, TMP/SMZ, and placebo subjects, respectively (p =.287). Ciprofloxacin 500 mg once daily provides safe and effective prophylaxis for travelers' diarrhea and is superior to TMP/SMZ (160/800 mg).

Journal Article↗
PubMed1994

Safe handling practices of cytotoxic drugs: the results of a chapter survey.

PURPOSE/OBJECTIVES: To describe how nurses from a local Oncology Nursing Society (ONS) Chapter Implement Occupational Safety and Health Administration (OSHA) guidelines for handling cytotoxic drugs (CDs) in their individual practices and to identify barriers to implementing these guidelines. DESIGN: Mailed survey. SETTING: ONS chapter in a large midwestern city. SAMPLE: 103 nurses, 83 of whom handle CDs. Mean years in oncology nursing was 7.5. METHODS: Mailed survey consisting of 48 questions on seven topics, as well as demographic questions. MAIN RESEARCH VARIABLES: Roles in preparation and administration of CDs, management spills, patient care, and use of protective equipment in patient and family education practices; barriers to use of protective practices. FINDINGS: Subjects used some protective equipment when preparing and administering CDs, but the type of equipment and its frequency of use did not specifically meet OSHA Guidelines. Rates of compliance with guidelines were better for management of spills and disposal of equipment. Verbal instructions for patients and families were employed but very few provided written instructions or explanations. Barriers to using protective equipment included a lack of time, problems with availability, and concerns about patient reactions. CONCLUSIONS: Barriers must be overcome and better safe-handling practices incorporated into practice to ensure the safety of nurses. More education is needed for family members who come into contact with patients receiving CDs. IMPLICATIONS FOR NURSING PRACTICE: Future research to document the extent of the problem, including stratification of responses according to the quantity and frequency with which a nurse administers CDs. Better, and perhaps more frequent, staff and family education efforts are needed.

Adult↗
PubMed1993

Serovar determination and molecular taxonomic correlation in Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum: a cooperative study of the International Working Group on Mycobacterial Taxonomy.

A cooperative study was conducted by the International Working Group on Mycobacterial Taxonomy to correlate the agglutination serovar designations of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum strains with the species ascriptions of these organisms according to molecular criteria and cultural properties and to assess the reproducibility of serovar determinations for a set of 63 reference strains of these species. Among the molecular criteria, the level of agreement between results obtained with nucleic acid probes and T-catalase serology results was 94% for strains of M. avium and M. intracellulare. Nucleic acid probes were not available for M. scrofulaceum, but none of the 10 strains ascribed to this species on the basis of catalase serology data reacted with a nucleic acid probe for M. avium or M. intracellulare. Ascription to a species on the basis of mycolic acid high-performance liquid chromatography patterns was in agreement with catalase serology results in 86% of the cases examined. Most strains belonging to serovars 1 through 6 and 8 through 11 were identified by molecular criteria as M. avium, most strains belonging to serovars 7, 12 through 20, 23, and 25 were identified as M. intracellulare, and most strains belonging to serovars 41 through 43 were identified as M. scrofulaceum, in agreement with common current practice. Evidence for assigning serovar 27 to M. scrofulaceum was obtained. However, two strains of a given serovar may, on occasion, be placed in different species. The dominant species assignments for strains belonging to serovars 21, 24, 26, and 28 remain unresolved.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination Tests↗
PubMed1993

Directional coronary atherectomy in acute myocardial infarction.

To date, application of directional coronary atherectomy (DCA) in acute myocardial infarction (AMI) has had limited reports. In eleven patients with AMI, DCA was applied. In three of these patients, DCA was used as a stand-alone procedure without use of thrombolytic agents. In each case a guidewire was placed across the stenosis, and in eight patients balloon angioplasty was utilized as a predilating modality prior to DCA. The thrombolytic agent urokinase was utilized in five of these eight patients, either before, during, or after angioplasty and/or DCA. DCA success (defined as ability to cross the lesion, reduction of less than or equal to 20% in stenosis and thrombolysis--when a thrombus is present) was achieved in 10 of 11 patients. One patient had persistent abrupt reclosure of an LAD lesion, accompanied by hemodynamic compromise, necessitating intra-aortic balloon pump insertion and subsequent emergent coronary artery bypass graft surgery. Final angiograms revealed residual stenoses less than or equal to 20%, and adequate thrombolysis. Significant cardiac events were limited to one emergent CABG, Q wave MI in four patients, and non-Q wave MI in two patients. Clinically all eleven patients improved, survived the AMI/CABG, and were discharged. This clinical experience demonstrates the feasibility and safety of DCA application in selected patients who experience acute myocardial infarction.

Adult↗
PubMed1992

Substituent variation in azabicyclic triazole- and tetrazole-based muscarinic receptor ligands.

The effect of variation of the 1-azabicyclic substituent on the novel 1,2,3-triazol-4-yl-, 1,2,4-triazol-1-yl, tetrazol-5-yl-, and tetrazol-2-yl-based muscarinic receptor ligands has been studied, and the exo-azabicyclic[2.2.1]hept-3-yl substituent was found to give the most potent and efficacious compounds. In addition, variation of the second substituent on 1,2,4-triazol-1-yl- and tetrazol-2-yl-based muscarinic receptor ligands has yielded a series of novel compounds with high potencies and efficacies, ranging from full agonists to antagonists. Small lipophilic electron withdrawing substituents give potent but low efficacy compounds, while small polar electron donating substituents give potent and efficacious compounds. The activity of these compounds is described in terms of a model of the receptor involving lipophilic and hydrogen bonding interactions. These compounds provide muscarinic ligands with high potency and a range of efficacies suitable for testing as candidate drugs in the treatment of Alzheimer's disease.

Alzheimer Disease↗
PubMed1992

Synthesis and muscarinic activities of quinuclidin-3-yltriazole and -tetrazole derivatives.

The synthesis of 15 methyl or unsubstituted 1,2,3-triazoles, 1,2,4-triazoles, and tetrazoles additionally substituted with a 1-azabicyclo[2.2.2]octan-3-yl group is described. The potency and efficacy of these compounds as muscarinic ligands were determined in radioligand binding assays using [3H]oxotremorine and [3H]quinuclidinyl benzilate. Potency and efficacy were found in compounds in which the azole moiety was attached to the azabicyclic ring either through a carbon atom or a nitrogen atom. Electrostatic potential maps of both the C-linked and the novel N-linked series of compounds were calculated. A relationship between position and depth of the electrostatic minima relative to the azabicyclic ring and the potency and efficacy of the compounds was determined.

Animals↗
PubMed1992

Self-reported sleep quality in college students: a repeated measures approach.

A longitudinal assessment of sleep quality is presented. Undergraduates provided two levels of repeated measures data. Sleep log information was gathered across the 7 days of the week, in three replications, over a semester. There were several new findings. Across the week, students spent significantly more time in bed on weekend days as compared with weekdays. Further, a new measure for quality of sleep covaried with the amount of time spent in bed during the week. The students enjoyed their sleep more on the weekends. Finally, both the amount of time in bed and the number of awakenings reported dropped significantly as the semester progressed.

Adolescent↗
PubMed1992

Identification of spinal cord polypeptides related to glial fibrillary acidic protein (GFAP).

Spinal cord cytoskeletal preparations from three different mammalian species contain several polypeptides in the SDS-PAGE molecular weight range 100-220 kDa which are recognized by all members of a panel of antibodies to glial fibrillary acidic protein (GFAP) and by anti-IFA, a panspecific intermediate filament protein antibody. The polypeptides are not recognized by antibodies to other intermediate filament proteins or to ubiquitin. The proteins coelute with GFAP in ion-exchange chromatography, cosediment with GFAP under filament assembly conditions, produce similar chemical digest patterns and have an amino acid profile close to that of pure GFAP, all properties expected for covalent GFAP multimers. Further experiments provide evidence for the existence of such multimeric complexes in vivo.

Amino Acids↗
PubMed1992

Physician recruitment: the elements of a successful search.

Before attempting to recruit a new physician for a practice, it is important to gain a background in the elements involved in a successful search--such as physician supply data, recruitment strategies, and incentives. Armed with an understanding of the physician market, recruiters are better prepared to proceed with a search that will meet the needs of potential candidates, as well as their own requirements.

Contract Services↗