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Biomedical subjects

B Johnson

Publications and source records attributed to B Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1998

Medical reference databases used by Army primary care physicians in field environments.

A cross-sectional survey of U.S. Army primary care physicians was done to answer two questions: (1) which medical reference materials are Army primary care physicians currently using when deployed to a field environment? and (2) what would they like to have for medical reference in a field environment? Of 740 surveys delivered to their intended recipients, 445 (60%) were returned. Currently, 96% of primary care physicians use books, 37% use journals, and 11% use computer software in their medical reference database. Of those now using books, 72% were satisfied with them, compared with 61% of those using journals and 45% of those using software. The most common book used was the Merck Manual. The most important characteristics desired in a field medical database were broad coverage, ease of use, and light weight. The majority of respondents believe that a good medial reference database is important but that current medical databases limit the quality of the medicine they practice in the field.

Attitude of Health Personnel↗
PubMed1997

Improved single-strand DNA sizing accuracy in capillary electrophoresis.

Interpolation algorithms can be developed to size unknown single-stranded (ss) DNA fragments based on their electrophoretic mobilities, when they are compared with the mobilities of standard fragments of known sizes; however, sequence-specific anomalous electrophoretic migration can affect the accuracy and precision of the called sizes of the fragments. We used the anomalous migration of ssDNA fragments to optimize denaturation conditions for capillary electrophoresis. The capillary electrophoretic system uses a refillable polymer that both coats the capillary wall to suppress electro-osmotic flow and acts as the sieving matrix. The addition of 8 M urea to the polymer solution, as in slab gel electrophoresis, is insufficient to fully denature some anomalously migrating ssDNA fragments in this capillary electrophoresis system. The sizing accuracy of these fragments is significantly improved by the addition of 2-pyrrolidinone, or increased capillary temperature (60 degrees C). the effect of these two denaturing strategies is additive, and the best accuracy and precision in sizing results are obtained with a combination of chemical and thermal denaturation.

Algorithms↗
PubMed1997

How Do Logical Inference Rules Help Construct Social Mental Models?

Starting from recent approaches in mental model research, it is argued that (1) logical inference rules are used in order to construct mental cliques from learned sentiment relations, and (2) social context cues (operationalized as primes) play a crucial role in activating such rules. Transitivity and antitransitivity are taken as examples, and are shown as core constituents of such models. In a first experiment, priming was achieved by announcing the sorting of fictitious persons in either two or three cliques. Thirty-one subjects studied eight sets of sentiment relations among these persons that either did or did not satisfy their primed clique expectations. They showed longer study times and more requests for additional information in the case of inconsistent fits between prime and set. Their sorting solutions also showed clear priming effects. A second experiment (n = 30) showed that when undergoing a recognition test after seeing the relation sets, subjects tended to confuse model-consistent distractors with information they had actually seen. In a third experiment (n = 30) the results from Experiment 1 were replicated using more realistic learning materials.

Journal Article↗
PubMed1997

Thalidomide and thalidomide analogs reduce HIV type 1 replication in human macrophages in vitro.

Thalidomide is currently being evaluated for efficacy in alleviating some manifestations of HIV-1 infection. To determine whether thalidomide has any direct effects on HIV-1 infection, we investigated the effect of thalidomide and also of three structural analogs of thalidomide on HIV-1 replication in vitro in human monocyte-derived macrophages. The thalidomide analogs were previously shown to inhibit TNF-alpha production in vitro at much lower concentrations than thalidomide. In HIV-1-infected macrophages treated with thalidomide or thalidomide analogs, viral replication was reduced by 60 to 80% as determined by measuring viral RT activity in the culture supernatants. In all experiments the analogs inhibited HIV-1 replication more efficiently than did thalidomide. The drugs also reduced HIV-1 gag mRNA expression. Furthermore, the drugs caused a decrease in NF-kappaB-binding activity in nuclear extracts of HIV-1-infected macrophages. The role of NF-kappaB in the drug-induced inhibition of HIV-1 replication was confirmed using an NF-kappaB-defective mutant virus to infect macrophages.

Anti-HIV Agents↗
PubMed1997

Adult obesity and functioning in the family of origin.

OBJECTIVE: This study investigated the relationship between eating and weight behaviors and functioning in individuals' families of origin. METHOD: Subjects were 237 women and 242 men enrolled in the RENO (Relationship of Energy, Nutrition, and Obesity) Diet-Heart Study, a prospective 5-year study of the effects of weight fluctuation on cardiovascular disease risk factors in normal weight and obese adults. Variables of primary interest included subjects' body mass index (BMI), age of onset of obesity, eating attitudes, lack of control while eating, and family functioning. RESULTS: In men, higher family cohesion was related to healthier eating attitudes and better control over eating, controlling for age, BMI, and adaptability, whereas higher adaptability (changing rules and poor leadership) was related to earlier onset of obesity and more disturbed eating attitudes. Cohesion and adaptability were not related to body weight or eating variables in women. DISCUSSION: The lower societal pressure on men to be thin may increase the importance of family factors in influencing their shape and weight.

Adaptation, Psychological↗
PubMed1997

Extending the Benefits of Recategorization: Evaluations, Self-Disclosure, and Helping

The Common Ingroup Identity Model proposes that if members of different groups conceive of themselves more as a single group rather than as two separate groups, intergroup bias will be reduced through processes involving pro-ingroup favoritism. The present research extended work on this model by investigating the effects of recategorization on intergroup behavior, specifically helping and self-disclosure, as well as evaluations. Participants first worked as members of two three-person groups, and then the two groups interacted under conditions designed to enhance a two-group representation or recategorization with an inclusive one-group representation. As expected, the manipulation of the intergroup contact situation that created stronger impressions of one group reduced intergroup bias in evaluations, self-disclosure, and helping. Furthermore, ratings of the extent to which the six participants felt like one group mediated the reduction in bias, particularly for evaluative bias. Conditions facilitating the generalization of the benefits of recategorization to group members not present and to other groups are considered.

Journal Article↗
PubMed1997

Determinants of vaginal-perineal integrity and pelvic floor functioning in childbirth.

OBJECTIVES: Our purpose was to evaluate risk factors for severe vaginal-perineal trauma and to ascertain determinants of pelvic floor strength. STUDY DESIGN: Secondary analysis of 459 nulliparous women enrolled in a randomized controlled trial of episiotomy was carried out. In a multivariate analysis we examined the association between (1) sulcus tears, (2) third- or fourth-degree tears, and (3) pelvic floor strength and selected demographic, physiologic, pregnancy-related, and intrapartum factors. RESULTS: Unemployment and shorter second stage of labor were significant predictors of sulcus tears. Episiotomy, forceps use, and birth weight were important predictors of third- and fourth-degree tears. Whereas perineal intactness (use of episiotomy and spontaneous tears) was not influenced by exercise, a strong exercise profile was associated with fewer third- and fourth-degree tears in the presence of episiotomy. Exercise did not influence the rate of sulcus tears. A total of 35% of the variability in postpartum pelvic floor strength was explained by antepartum strength; however, we were only able to identify 5% of the factors contributing to antepartum pelvic floor strength. CONCLUSIONS: Determinants of sulcus tears appear to be present before pregnancy; third- and fourth-degree tears are related to physician management. Exercise mitigates the potential for severe trauma induced by episiotomy.

Adolescent↗
PubMed1997

Efficacy of electrical stimulation at frequencies higher than basal rate in canine stomach.

The optimum frequency for electrically stimulating motility in the stomach is still in question. Some studies of gastric electrical stimulation (GES) at near physiologic frequencies have reported gastric electrical entrainment but with little efficacy in improving motility. In this study we examined the effectiveness of electrical stimulation at a broad range of frequencies in entraining gastric electrical activity (GEA) and eliciting contractions in a canine model. The stomachs of six dogs, each implanted with four pairs of stainless steel electrodes and two strain gauges were stimulated at frequencies ranging from 3 to 30 cycles/min. GEA and contractions were monitored before and during electrical stimulation. The ability of GES at different frequencies to reverse the effect of glucagon was also investigated. GEA was entrained in most animals at frequencies close to the intrinsic rate as well as at four to five times the intrinsic rate. At other stimulation frequencies, the recorded electrical control activity either remained unchanged, uncoupled, or became dysrhythmic. Contractile response to stimulation at four to five times the intrinsic rate were significantly higher than those at frequencies close to the intrinsic rate (P < 0.05). GES did not alter the effect of glucagon. Stimulation at a frequency of four times the basal rate of 5/min elicited the largest motility index in dogs. Stimulation at frequencies much higher than the physiologic rate warrants further study as a possible optimum range for GES.

Animals↗
PubMed1997

The experience of thought-disordered individuals preceding an aggressive incident.

The purpose of this qualitative study was to increase the understanding of the experiences of individuals with thought disorders, which precede incidents of aggression. Twelve individuals, from two hospitals, who had a nursing diagnosis of thought disorder and a history of aggression were interviewed, between one and four times, to collect baseline information and information about particular aggressive incidents. The participants described in their own words their thoughts, feelings and experiences preceding the aggressive incidents. Three themes emerged. First, participants perceived themselves to be strongly affected by the external environment; their responses to aspects of the environment were influential in precipitating the aggressive incident. Second, participants perceived themselves, paradoxically, to be both powerful and powerless; the act of aggression becomes an incident of brief self-empowerment. Third, the aggressive incident occurred in spite of the participants' acknowledgement and previous use of anger-controlling strategies; the participants' perceptions of themselves as powerless in an oppressive environment may have mitigated against the success of these strategies. Nurses need to know what triggers aggressiveness in psychiatric patients, in order to intervene effectively. Mental health professionals must also reexamine the psychiatric hospital environment, to make sure they are not needlessly exacerbating their patients' powerlessness with policies that are unjustifiably controlling.

Adult↗
PubMed1997

Role of calcium in modulation of toxicities due to cisplatin and its analogs: a histochemical approach.

Cisplatin, carboplatin and paclitaxel (taxol) are potent antineoplastic agents with associated toxicities, especially gastrointestinal and nephrotoxicity that are their dose-limiting factors in clinical oncology. In an attempt to elucidate their mechanism(s) of toxicity, liver and kidney tissues from normal and drug treated rats and dogs were evaluated for changes in various dehydrogenase and non-specific lipase enzymes. Histochemically, cisplatin treatment induced an inhibition of all the enzymes studied except glucose-6-phosphate dehydrogenase and non-specific lipases, where there was a significant increase. Supplemental treatments with calcium [1 ml of 1.3% CaCl2/day in rats and 2.50 mg (150000 USP units) ergocalciferol plus 1000 mg of elemental calcium as TUMS 500 (EffeCal)/day in dogs] seem to protect against severe gastrointestinal toxicity and nephrotoxicity.

Adenosine Triphosphate↗
PubMed1997

The needs of parents of pediatric oncology patients during the palliative care phase.

The death of a child is considered one of the greatest stresses a parent can experience. It has been suggested that death from childhood malignancies is more stressful for parents than death due to other chronic diseases. The purpose of this qualitative study is to identify parents' perceptions of their needs while their child was dying of cancer. Twelve parents of eight children, who died of various types of cancer 1 to 3 years ago, were interviewed by the primary investigator. These children died either in hospital or at home. Interviews were tape recorded, transcribed and analyzed by the investigators. Three needs were identified: (1) The need to have the child recognized as special while retaining as much normality within the child's and family's lives as possible; (2) The need for caring and connectedness with health care professionals; and (3) The need to retain responsibility of parenting their dying child. Findings suggest that parental needs are similar regardless of where the death occurred. Implications for nursing practice and areas for further research were identified.

Adolescent↗
PubMed1996

Purification of the growth hormone releasing hormone receptor with a C-terminal, biotinylated affinity ligand.

The receptor for growth hormone-releasing hormone (GHRH) has been purified from bovine pituitary tissue and HEK293 cells transfected with human or porcine receptor using a retrievable biotinylated GHRH analog. Custom synthesized [His1, Nle27, Biotin-Lys41]-human GHRH-(1-41)-NH2 (GHRHb) bound to pituitary membranes with affinity comparable to human GHRH. GHRHb which has the biotinyl group on the C-terminus of the peptide allowed simultaneous binding to both the receptor and streptavidin agarose. This analog was used directly in the purification of the receptor from pituitary tissue or was modified by incorporation of the photoaffinity group ANBNOS (GHRHlambdab), radioiodinated and used to demonstrate purification of the GHRH receptor from transfected HEK293 cell membranes. Membranes were prepared and prebound with the respective ligand followed by CHAPS-solubilization and application of the solubilized complex to a streptavidin agarose column. Analysis of eluates from the pituitary tissue purification by silver stained SDS PAGE or of autoradiographs of gels from HEK293 eluates revealed specific bands of 52 and 55 kDa, respectively. The higher size of the latter band is expected for the ligand-crosslinked receptor. Both bands displayed similar mobility shifts of 10 kDa upon treatment with N-glycosidase, a method previously used to characterize this receptor. A 45 kDa band corresponding to the size of the Gs alpha subunit was also detected in eluates of the silver stained gels, suggesting that the GHRH receptor was retrieved as a heterotrimeric complex. Fold purification and yield for this procedure were estimated to be greater than 50,000 and 2.6-9%, respectively.

Animals↗
PubMed1996

Circulating concentrations of proinflammatory cytokines in mild or moderate heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

Proinflammatory cytokines are capable of modulating cardiovascular function by a variety of mechanisms. These cytokines are elevated in patients with severe heart failure, but changes in mild or moderate heart failure have not been reported. Therefore, simultaneous arterial and coronary sinus concentrations of interleukin-1alpha, soluble interleukin-2 receptor, interleukin-6, and tumor necrosis factor-alpha were measured in 78 patients with New York Heart Association functional class II to IV heart failure and compared with 17 healthy volunteers. Concentrations of interleukin-1alpha, soluble interleukin-2 receptor, and interleukin-6 were determined by a "sandwich" enzyme-linked immunosorbent assay and tumor necrosis factor-alpha by tissue culture technique. There were no statistical differences in interleukin-1alpha, soluble interleukin-2 receptor, or tumor necrosis factor-alpha concentrations in mild to moderate heart failure versus control subjects. Interleukin-6 was significantly elevated, 75 +/- 16 versus 0.4 +/- 0.4pg/ml (p = 0.002). Cytokine concentrations did not differ by heart failure etiology. Paired arterial and coronary sinus concentrations were not significantly different. Soluble interleukin-2 receptor concentrations were significantly correlated with New York Heart Association functional class (r = 0.59, p = 0.04) and negatively associated with exercise tolerance time (r = -0.59, p = 0.007). Thus, interleukin-6 is significantly elevated in mild or moderate heart failure.

Adrenergic alpha-Agonists↗