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Biomedical subjects

J Roberts

Publications and source records attributed to J Roberts.

At least 451 records · Page 25Linked to original sources
PubMed1989

Teaching psychomotor skills in nursing: a randomized control trial.

Historically, McMaster University School of Nursing in Hamilton, Ontario, Canada has utilized self-directed learning methods to teach psychomotor nursing skills to undergraduate nursing students. Second year students, in their post-clinical evaluations indicated a desire for a structured laboratory setting to assist them in acquiring these skills. In response, faculty designed a randomized control trial to compare the effectiveness of teaching psychomotor skills in a structured laboratory setting with self-directed self-taught modules. The results of this study substantiated the hypothesis of no difference between psychomotor skill performance of students who learn in a self-directed manner and those taught in a structured clinical laboratory.

Clinical Competence↗
PubMed1989

Learning clinical teaching skills at the baccalaureate level.

Nurses returning to work after obtaining their baccalaureate degree in nursing find increased expectations to participate in student and staff clinical education. Often these nurses are not prepared for this role. This paper describes a project that involved final year post-diploma registered nurse students in the clinical teaching of second year basic degree students in a baccalaureate nursing programme. Results of a pilot study to determine if the perceptions of the students involved in the teaching project changed following the experience, show a more positive change in teacher behaviours in these student tutors compared to students doing a traditional clinical experience. Course evaluations indicate the experience increased knowledge and comfort in clinical teaching and point to positive changes in the perceptions of behaviours conducive to clinical teaching.

Clinical Competence↗
PubMed1989

Acid giemsa technique for rapid identification of mitotic cells.

We developed a rapid technique for differential staining of compacted chromatin as a tool for screening of large tissue culture cell populations for mitotic cells. With a combination of acid Giemsa staining and counterstaining, differential staining of mitotic cells and classification according to stage of mitosis can be accomplished at magnifications as low as x 50-100 (objectives of x 5-10). The mapped and classified cells can then be de-stained and re-studied for DNA content by Feulgen staining and/or for uptake of radioactive DNA precursors by autoradiography. The staining and de-staining procedures outlined do not affect the reproducibility and accuracy of DNA content measurements or measurements of radioactive uptake. Therefore, this technique can be used for cell kinetic analysis by the percentage labeled mitoses method and for cytophotometric studies of mitotic segregation.

Autoradiography↗
PubMed1989

Transvaginal sonography in the evaluation of normal early pregnancy: correlation with HCG level.

Transvaginal sonography (TVS) is the procedure of choice in evaluating the viability of embryos early in pregnancy. However, viability based on TVS can be assessed more accurately when the exact gestational age from the last menstrual period is known or when the findings are correlated with beta human chorionic gonadotropin (HCG) levels. No large series has been reported with correlative data between early pregnancy findings, HCG, and gestational age. We performed 75 transvaginal examinations in 53 patients with proved normal pregnancy in the fifth through seventh weeks of gestation. The presence and size of the gestational sac, presence of a yolk sac, and identification of embryonic heart activity were correlated with the level of HCG. Sac size was correlated with yolk sac and heart activity and the three parameters correlated with gestational age in days. When the level of HCG reached 1000 mIU/ml by using the first International Reference Preparation, a gestational sac was seen sonographically in each patient. When the HCG level reached 7200 mIU/ml, a yolk sac was seen in every patient. Ten of 22 patients with HCG between 1000 and 7200 mIU/ml had a visible yolk sac. Every patient with an HCG level greater than 10,800 mIU/ml had a visible embryo with a heartbeat. A discriminatory level of 32 days was found for the presence of a gestational sac. A yolk sac was first seen in every patient between 36 and 40 days. Every patient with accurate dates greater than 40 days had an embryo with a heartbeat identified. When correlating sac size with structures within the sac, a yolk sac was first seen in a gestational sac between 6 and 9 mm and a heartbeat seen in every patient with a 9-mm or greater gestational sac diameter. These data allow identification of normal intrauterine pregnancy and distinction of normal from ectopic gestation at least 1 week earlier than is possible with transabdominal techniques.

Chorionic Gonadotropin↗
PubMed1989

The Uganda I/CDC strain of Plasmodium malariae in Aotus lemurinus griseimembra monkeys.

Two lines of the Uganda I/CDC strain of Plasmodium malariae were studied in splenectomized Aotus lemurinus griseimembra monkeys. A line initially adapted to these monkeys from an infected chimpanzee failed to produce high-level parasite counts or mosquito infection in 13 of this type of monkey during 16 linear passages. Another line, originally adapted from the chimpanzee to Aotus azarae boliviensis, after 7 linear passages in 3 different types of Aotus was then passaged to 14 splenectomized A. lemurinus griseimembra. Geometric mean maximum parasitemia in these monkeys was 18,400/mm3. Mosquito infections were readily obtained during the period just after the parasite count rose above 1,000/mm3. Anopheles freeborni, An. stephensi, An. dirus, and 2 strains of An. gambiae supported the development of the parasite to the presence of sporozoites in the salivary glands. Two attempts to transmit the strain to other splenectomized A. lemurinus griseimembra by sporozoite inoculation were unsuccessful.

Animals↗
PubMed1988

Structures of amidohydrolases. Amino acid sequence of a glutaminase-asparaginase from Acinetobacter glutaminasificans and preliminary crystallographic data for an asparaginase from Erwinia chrysanthemi.

The complete amino acid sequence of a glutaminase-asparaginase from Acinetobacter glutaminasificans, for which a preliminary tertiary structure is available from crystallographic analysis, has been determined by automated Edman degradation of fragments produced by chemical and proteolytic cleavages. The protein consists of 331 amino acid residues and has a molecular weight of 35,500. The pattern of hydrophilic and hydrophobic regions is typical of a globular protein. A new crystal form of an Erwinia chrysanthemi 1125 asparaginase is reported. The space group is monoclinic C2, with unit cell parameters of: a = 107.8, b = 91.7, c = 129.2 A and beta = 91.7 degrees. A Vm of 2.25 A3/dalton was calculated for one tetramer of 35,100-dalton subunits per asymmetric unit. X-ray intensity data have been obtained to 2.2 A resolution. The point group symmetry of the Er. chrysanthemi tetramer is 222 from self-rotation function calculations. The relative orientations of an A. glutaminasificans glutaminase-asparaginase model and the Er. chrysanthemi asparaginase tetramer have been determined with the cross-rotation function, and translation function calculations have revealed a plausible location for the asparaginase tetramer in the crystal.

Acinetobacter↗
PubMed1988

Uptake of glutamine antimetabolites 6-diazo-5-oxo-L-norleucine (DON) and acivicin in sensitive and resistant tumor cell lines.

The uptake system for 6-diazo-5-oxo-L-norleucine (DON) was studied in mouse P388 leukemia cells. The DON transport system was found to resemble that of another glutamine antimetabolite, Acivicin, in its strong temperature dependence, utilization of the "L" transport system, inhibition by glutamine but not by glutamate, potent inhibition by p-chloromercuribenzene sulfonate, Na+, and only minimal inhibition by various energy poisons. A Km of approximately 70 microM and a Vmax of 3.4 nmoles/10(6) cells/min was calculated for this cell line. The accumulated DON was not metabolized by P388 cells and moderate efflux occurred at 37 degrees C. The DON transport characteristics of a DON-resistant P388 cell line (100 times ID50 of parent line) were similar to those of the DON-sensitive parent line, indicating that altered drug transport may not be involved in development of resistance to this antimetabolite. The finding that an Acivicin-resistant subline of P388 cells which exhibited good transport of DON showed negligible transport of Acivicin suggests different modes of resistance towards the two glutamine antimetabolites.

Animals↗
PubMed1988

Preliminary crystal structure of Acinetobacter glutaminasificans glutaminase-asparaginase.

The preliminary structure of a glutaminase-asparaginase from Acinetobacter glutaminasificans is reported. The structure was determined at 3.0-A resolution with a combination of phase information from multiple isomorphous replacement at 4-5-A resolution and phase improvement and extension by two density modification techniques. The electron density map was fitted by a polypeptide chain that was initially polyalanine. This was subsequently replaced by a polypeptide with an amino acid sequence in agreement with the sizes and shapes of the side chain electron densities. The crystallographic R factor is 0.300 following restrained least squares refinement with data to 2.9-A resolution. The A. glutaminasificans glutaminase-asparaginase subunit folds into two domains: the aminoterminal domain contains a five-stranded beta sheet surrounded by five alpha helices, while the carboxyl-terminal domain contains three alpha helices and less regular structure. The connectivity is not fully determined at present, due in part to the lack of a complete amino acid sequence. The A. glutaminasificans glutaminase-asparaginase structure has been used successfully to determine the relative orientations of the molecules in crystals of Pseudomonas 7A glutaminase-asparaginase, in crystals of Vibrio succinogenes asparaginase, and in a new crystal form of Escherichia coli asparaginase (space group 1222, one subunit per asymmetric unit).

Acinetobacter↗
PubMed1988

Does chlorpromazine produce cardiac arrhythmia via the central nervous system?

The influence of the central nervous system in the production of phenothiazine-induced arrhythmia and death was examined in this study. In a series of cats, spinal cords were transected at the atlanto-occipital junction prior to the 1 mg/kg/min, i.v. infusion of chlorpromazine or thioridazine. No protection against drug-induced arrhythmia or death was afforded by this procedure. In other cats, 6OH-dopamine was administered prior to intravenous injection of atropine and infusion of chlorpromazine, 1 mg/kg/min. In these in situ denervated heart preparations, there was no protection against chlorpromazine-induced arrhythmia or death. In alpha-chloralose anesthetized cats, 0.5 mg chlorpromazine administered intracerebroventricularly did not induce arrhythmia or death, although blood pressure decreased initially. Thus, chlorpromazine or thioridazine do not appear to produce arrhythmia or death via a central locus and may instead be acting directly on myocardial conduction to produce arrhythmia and death.

Animals↗
PubMed1988

Gender differences in variables associated with psychosocial adjustment to a burn injury.

The purpose of this study was to determine whether variables associated with psychosocial adjustment to a burn injury vary by gender. Male and female burned subjects (N = 260) were compared on their functional disability, disfigurement, coping responses, social resources, and psychosocial adjustment to a burn injury. Both men and women had adjusted psychosocially to their burn injury. Less functional disability (r = .57, p less than .001) for men and greater problem-solving (r = .57, p less than .001) for women were the most important variables in explaining psychosocial adjustment to a burn injury. In the future, researchers need to be cognizant of gender differences and consider men and women as separate populations.

Adaptation, Psychological↗
PubMed1988

Effect of increasing age on adrenergic control of heart rate in the rat.

To determine if decreased cardiac rate with increasing age in Fischer-344 rats was due to changes in the heart itself, in adrenergic nerves innervating the heart or in both, we studied heart rate in vivo and in vitro, and atrial and ventricular pacemaker activity in vitro following atrioventricular block, in control and in chemically sympathectomized rats [pretreated with 6-hydroxydopamine (6-OHDA), 20 mg/kg, s.c., 24 h prior to testing] at ages 1 to 28 months. With increasing age, heart rate (bpm) in vivo decreased from 440 +/- 12 to 385 +/- 10 in the control and from 403 +/- 20 to 318 +/- 11 in 6-OHDA pretreated rats; heart rate in vitro decreased from 353 +/- 9 to 243 +/- 8 in the control, and from 346 +/- 15 to 214 +/- 18 in 6-OHDA pretreated rats; the atrial rate (AR) decreased from 304 +/- 9 to 210 +/- 8 in the control and from 288 +/- 13 to 161 +/- 32 in 6-OHDA pretreated rats while the ventricular pacemaker rate (VR) decreased from 121 +/- 8 to 92 +/- 5 in the control, and from 100 +/- 14 to 70 +/- 7 in 6-OHDA pretreated rats. With age, AR decreased to a greater extent than VR and 6-OHDA had a greater effect in decreasing AR than VR. Using cardiac rate as a measure, it appears that with age changes in the pacemakers of the heart themselves (postjunctional) as well as in the adrenergic nerve endings innervating the heart (prejunctional) contribute to decreased cardiac rate and pacemaker activity in older rats.

Aging↗