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Biomedical subjects

R Smith

Publications and source records attributed to R Smith.

At least 1,315 records · Page 73Linked to original sources
PubMed1983

Differences in maternal lineages of New Zealand Black mice defined by restriction endonuclease analysis of mitochondrial DNA and by expression of maternally transmitted antigen.

Two substrains of New Zealand Black (NZB) mice have been compared with respect to expression of a maternally transmitted cell surface antigen, Mta, defined by cloned cytolytic T cells, and for restriction enzyme polymorphisms of mitochondrial DNA (mtDNA). These independent assays of maternal cytoplasmic inheritance provide strong evidence for genetic contamination of the NZB/BlPt substrain (NZB/Bl mice from Michael Potter's separate colony at the National Institutes of Health), in which the typical NZB immunologic abnormalities are at least partially ameliorated. The decisive data are the restriction enzyme maps of mtDNA for NZB/BlPt, which were identical with those of the common "old inbred" strains and quite different from those of NZB/BlN (NZB/Bl mice from the breeding facility at the National Institutes of Health). It is probable that the contamination of the NZB/BlPt substrain is related to phenotypic changes in their autoimmune state. More interestingly, the data are consistent with, although they do not prove, involvement of the mitochondrial genome in expression of a cell surface molecule.

Animals↗
PubMed1983

A comparison of the efficacy of sotalol and nadolol in the suppression of ventricular ectopic beats.

The anti-arrhythmic efficacy of sotalol, a beta-blocking agent which possesses class III anti-arrhythmic properties, was compared with that of nadolol. Nadolol, like sotalol, is non-cardioselective, is water-soluble, has no first-pass effect, is excreted unchanged in the urine, has a comparatively long half-life requiring only once-daily dosage, and has no intrinsic sympathomimetic activity and no membrane-stabilizing action. Twenty-two patients with stable chronic ventricular arrhythmias after myocardial infarction were studied; to qualify for entry they had to exhibit a minimum frequency of 30 ventricular ectopic beats per hour over a 24-hour Holter monitoring period. The study was of single-blind, cross-over format with placebo periods before active drug administration and during the cross-over periods. Nadolol 80 and 160 mg and sotalol 160 and 320 mg were administered for 7-day periods. Routine laboratory tests were performed and serum drug concentrations measured at regular intervals. Both drugs at all dosages suppressed ventricular ectopic beats significantly (P less than 0,001). No statistically significant prolongation of the QTc interval could be demonstrated with either drug. Side-effects were negligible.

Adult↗
PubMed1983

The dilemma of the creatine kinase cardiospecific iso-enzyme (CK-MB) in marathon runners.

Serum creatine kinase iso-enzyme (CK-MB) levels were measured in 51 marathon runners before and after a 50 km marathon event. Ninety-five per cent of the runners were found to have pathologically elevated values, i.e. CK-MB concentrations were elevated to the range normally considered indicative of myocardial necrosis. Results indicate that a rise in the CK-MB level is common after marathon running. We therefore believe that cardiac enzymes are an unreliable indicator of myocardial infarction in patients who experience chest pain following strenuous muscular exercise.

Adult↗
PubMed1983

Holter monitoring--a necessity for the evaluation of palpitations.

Eighty-five patients complaining of palpitations were evaluated by means of 24-hour dynamic electrocardiography. A sensitivity of 0,69 and a specificity of 0,90 were calculated. This illustrates the value of Holter monitoring in the assessment of patients complaining of palpitations.

Adolescent↗
PubMed1983

Self-regulation and external reinforcement in problem-solving strategies of black adolescents.

Examined the relationships among self-regulatory behaviors, perceptions of social reinforcement from significant persons, and the problem-solving performance of black adolescents (N = 33). The components of self-regulatory processes--self-reinforcement, self-evaluation and self-monitoring--were interrelated highly. Ss' perception of neither positive nor negative social reinforcement was related significantly to problem-solving performance. Discussion centered around the effects of self-responsibility and affective factors in the achievement orientation of minority children.

Achievement↗
PubMed1983

Effects of mitogenic stimulation of lymphocytes on lysosomal enzyme activity.

Changes in the activities of several lysosomal enzymes were studied during transformation of mouse spleen cells in vitro. The activity of beta-glucuronidase increased during culture in the presence of T or B-cell mitogens, and lymphoblasts contained higher levels of activity than did small, non-transformed lymphocytes. Moreover, lymphoblasts in well-transformed cultures had higher activities than those in poorly-transformed cultures. The activities of other lysosomal enzymes (N-acetyl-beta-glucosaminidase, alpha-mannosidase, beta-glucosidase) also increased during mitogenic stimulation, but each at different rates, although aryl sulphatase was unaffected. Such differences may be of importance when lymphocytes are used for diagnosis of inherited lysosomal deficiency diseases.

Acetylglucosaminidase↗
PubMed1983

Adenosinetriphosphatase (Mg-ATPase) activity in the plasma membrane of preimplantation mouse embryo as revealed by electron microscopy.

The ultrastructural localization of Mg2+-ATPase activity was investigated in unfertilized eggs and in preimplantation mouse embryos. Enzyme activity was detected on the entire surface of unfertilized eggs and in one-cell embryos. From the two-cell stage up to the 12-cell embryo the reaction product was localized both at the exposed surface of the embryo and between blastomeres. At the late morula stage, activity was only present on the free surface of the peripheral cells outside the apical tight junctions. In the early blastocyst the membranar reaction was observed both on the outside membrane of the trophoblastic cells and on the inner surface facing the blastocoele, whereas in the late blastocyst the reaction remained unchanged on the outer surface of the embryo but was absent from the membranes bordering the blastocoele. These results are discussed with reference to the modification of the cell surface membrane during preimplantation development.

Adenosine Triphosphatases↗
PubMed1983

Cardiovascular abnormalities in osteogenesis imperfecta.

To investigate the prevalence of cardiac abnormalities in osteogenesis imperfecta we performed a clinical and echocardiographic study on 20 patients. One patient had aortic regurgitation, 13 had soft late apical systolic murmurs (without significant mitral regurgitation), and seven had systemic hypertension. In only one patient was there echocardiographic evidence of mitral valve prolapse. The aortic root diameter exceeded the normal range in six patients, two of whom were hypertensive. The overall mean value (+/- 1 S.D.) in the 16 patients without marked skeletal deformity was 2.02 +/- 0.33 cm/m2. The echocardiographic appearances suggested that the left-sided valve cusps were thin, and in 13 patients the aortic valve leaflets showed a coarse systolic flutter.

Adolescent↗
PubMed1983

Tumorigenesis by mouse mammary tumor virus: evidence for a common region for provirus integration in mammary tumors.

We have prepared specific probes for unique-sequence cellular DNA adjacent to each of the newly integrated proviruses in tumors induced by mouse mammary tumor virus (MMTV). The use of such probes to screen a large number of independent mammary tumors in the BR6 strain of mouse has indicated that in at least 17 out of the 40 tumors examined so far, an MMTV provirus has integrated into a common chromosomal domain. A 10 kb Eco RI fragment of single copy DNA from this region has been isolated and partially characterized by restriction enzyme mapping. Of the proviruses located within this fragment in different tumors, all but one are complete, in the same orientation, and clustered within about 3 kb of cellular DNA. These findings are consistent with an insertional mutagenesis model for tumorigenesis by MMTV, in which the integration of a provirus in a particular region of cellular DNA may activate a neighboring oncogene. The region we describe here appears to be different from that reported for mammary tumors in the C3H strain of mouse.

Animals↗
PubMed1983

Serial dexamethasone suppression test results during antidepressant therapy: relationship to diagnosis and clinical change.

Thirty-two outpatients with major depression of mild to moderate severity were given a 1 mg dexamethasone test (DST) after 1 week of placebo. Those who failed to show a response to placebo began a 6-week course of desipramine treatment. Severity ratings and the DST were repeated during biweekly visits. DST results robustly validated Winokur's familial subtyping and the primary/secondary distinction only when multiple results were considered. The use of multiple DSTs doubled the sensitivity of this test to primary depression and to familal pure depressive disorder without affecting specificity. Based on these data, a single abnormal DST result is considerably more meaningful than a single normal one. This finding may have particular importance to outpatients.

Depressive Disorder↗
PubMed1983

Reality orientation with elderly patients in the community: an empirical evaluation.

There is now good evidence that elderly mentally impaired patients can be re-orientated for time, place and person using the technique of reality orientation (RO). To date, all empirical trials demonstrating this have been carried out on elderly institutionalized patients. This technique however might be of greater value to those elderly dementing patients still living with relatives in the community but attending geriatric psychiatry day hospitals, where they could receive RO in a consistent and systematic way. The results of an empirical study of RO with a group of such patients is reported. These showed that day hospital patients could be effectively re-orientated and that concomitant with changes in level of orientation of the patients, there were parallel changes in the patients' behaviour at home, reported stress on relatives and in relatives' mood.

Aged↗
PubMed1983

The use of videotape programs to teach interpersonal skills.

Interpersonal skills training evolved rapidly in recent years as teachers began to exploit the distinct advantages of "live" and simulated presentations in videotapes and films as teaching aids. At the same time, psychologists and psychiatrists started to define the basic aspects of interpersonal relations. Many used prepared scripts to produce videotape programs that modeled human interactions. While clinical experience and formal studies clarified some characteristics of effective visual training programs, the impact of dramatic and technical elements in these productions was not fully explored. In the present paper, the authors review the nature of interpersonal skills and the current status of visual aids for teaching human relations and show how videotape productions with characters, a story line, and action sequences can enhance learning. The experience of producing a series of videotapes about prehospital emergency care is used as a paradigm for discussing how theatrical techniques, applied through discrete production steps, can reinforce training goals and appeal to a wide range of students with diverse learning styles.

Clinical Competence↗
PubMed1983

Effect of oral hygiene instruction on brushing skills in preschool children.

This study provides new information on the assessment of toothbrushing skills in preschool children. 420 children aged 2-4 years were given a single lesson on toothbrushing. Their levels of toothbrushing skills, in terms of the locations of the tooth surfaces brushed, were recorded before and after the lesson. The number of skills per child possessed before the lesson (innate skills) and the number acquired from the lesson, both increased with age. A high correlation was found between the proportion of children innately possessing a particular skill and the proportion who subsequently learned it from the lesson. An effectiveness index was devised to help compare the relative difficulty and utility of teaching different skills at different ages.

Age Factors↗