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Biomedical subjects

S L Jones

Publications and source records attributed to S L Jones.

At least 55 records · Page 3Linked to original sources
PubMed1998

Effects of noradrenergic agonists on superficial dorsal horn neurons in the cat spinal cord.

The objectives of the present study were to determine the effects of iontophoretically-applied noradrenergic agonists on the unit activity of physiologically characterized superficial dorsal horn neurons in the barbiturate-anesthetized cat spinal cord, and to determine if a relationship exists between the effects produced by these agents and neuron modality. The effects of norepinephrine (NE), clonidine (CLON, a selective alpha2-agonist) and phenylephrine (PE, a selective alpha1-agonist) on spontaneous and D,L-homocysteic acid (DLH)-evoked unit activity were examined for 68 superficial dorsal horn neurons. Iontophoretically applied NE inhibited (40% of the cells examined) and excited (39% of the cells examined) unit activity. Mixed effects (i.e., inhibition and excitation) on unit activity also were observed (10% of the cells examined), and NE had no effect on the unit activity of some cells (11% of the cells examined). Excitation was the predominant effect produced by CLON (62% of the cells examined); however, inhibition (19% of the cells examined), mixed effects (5% of the cells examined), and no effects on unit activity (14% of the cells examined) also were observed. Iontophoretically applied PE inhibited (46% of the cells examined) and excited (36% of the cells examined) unit activity. Mixed effects on unit activity also were observed (4% of the cells examined), and PE had no effect on the unit activity of some cells (14% of the cells examined). Whether NE, CLON or PE exerted excitatory or inhibitory effects on unit activity did not depend on neuron modality.

Adrenergic alpha-Agonists↗
PubMed1998

Two signaling mechanisms for activation of alphaM beta2 avidity in polymorphonuclear neutrophils.

Circulating polymorphonuclear neutrophils (PMN) are quiescent, nonadherent cells that rapidly activate at sites of inflammation, where they develop the capacity to perform a repertoire of functions that are essential for host defense. Induction of integrin-mediated adhesion, which requires an increase in integrin avidity, is critical for the development of these effector functions. Although a variety of stimuli can activate integrins in PMN, the signaling cascades involved are unclear. Phosphatidylinositol (PI) 3-kinase has been implicated in integrin activation in a variety of cells, including PMN. In this work, we have examined activation of the PMN integrin alphaM beta2, assessing both adhesion and generation of the epitope recognized by the activation-specific antibody CBRM1/5. We have found that PI 3-kinase has a role in activation of alphaM beta2 by immune complexes, but we have found no role for it in alphaM beta2 activation by ligands for trimeric G protein-coupled receptors, including formylmethionylleucylphenylalanine (fMLP), interleukin-8, and C5a. Cytochalasin D inhibition suggests a role for the actin cytoskeleton in immune complex activation of alphaM beta2, but cytochalasin has no effect on fMLP-induced activation. Similarly, immune complex activation of the Rac/Cdc42-dependent serine/threonine kinase Pak1 is blocked by PI 3-kinase inhibitors, but fMLP-induced activation is not. These results demonstrate that two signaling pathways exist in PMN for activation of alphaM beta2. One, induced by FcgammaR ligation, is PI 3-kinase-dependent and requires the actin cytoskeleton. The second, initiated by G protein-linked receptors, is PI 3-kinase-independent and cytochalasin-insensitive. Pak1 may be in a final common pathway leading to activation of alphaM beta2.

Cell Adhesion↗
PubMed1998

Noxious heat-evoked fos-like immunoreactivity in the rat lumbar dorsal horn is inhibited by glutamate microinjections in the upper cervical spinal cord.

Microinjections of glutamate into the upper cervical spinal cord significantly reduced (to 57% of control) the total number of neurons demonstrating noxious heat-evoked fos-like immunoreactivity in the lumbar spinal cord. Neurons in the upper cervical spinal cord, with descending propriospinal projections to the lumbar spinal cord, therefore, produce inhibitory effects on dorsal horn neurons in the lumbar spinal cord that receive nociceptive input from cutaneous thermal nociceptors.

Animals↗
PubMed1998

Re-feeding after starvation involves a temporal shift in the control site of glycogen synthesis in rat muscle.

The starved-to-fed transition is accompanied by rapid glycogen deposition in skeletal muscles. On the basis of recent findings [Bräu, Ferreira, Nikolovski, Raja, Palmer and Fournier (1997) Biochem. J. 322, 303-308] that during recovery from exercise there is a shift from a glucose 6-phosphate/phosphorylation-based control of glycogen synthesis to a phosphorylation-based control alone, this paper seeks to establish whether a similar shift occurs in muscle during re-feeding after starvation in the rat. Chow re-feeding after 48 h of starvation resulted in glycogen deposition in all muscles examined (white, red and mixed quadriceps, soleus and diaphragm) to levels higher than those in the fed state. Although the early phase of re-feeding was associated with increases in glucose 6-phosphate levels in all muscles, there was no accompanying increase in the fractional velocity of glycogen synthase except in the white quadriceps muscle. This finding, together with the observation that the fractional velocity of glycogen synthase in most muscles was already high in the starved state, suggests that in the initial phase of glycogen deposition the phosphorylation state of the enzyme may be adequate to support net glycogen synthesis. In the later phase of re-feeding, the progressive decrease in the fractional velocity of glycogen synthase in association with a decrease in the rate of glycogen deposition suggests that glycogen synthesis is controlled primarily by changes in the phosphorylation state of glycogen synthase. In conclusion, this study suggests that there is a temporal shift in the site of control of glycogen synthesis as glycogen deposition progresses during re-feeding after starvation.

Animals↗
PubMed1998

Structural equation modeling and its relationship to multiple regression and factor analysis.

Using a conceptual and nontechnical approach, the meaning of structural equation modeling (SEM) and the similarities to, and differences from, more commonly used procedures such as correlation, regression, path analysis, and factor analysis are explained. Application of the statistical technique is presented using data from a study of the relationships among stresses, strains, and physical health in a random sample of 492 community-dwelling elders aged 65 and older. Advantages of each statistical procedure are described. Theoretical issues related to the use of each procedure are presented with emphasis on the need for a sound theoretical model and match between the statistical procedure and the aims of the analysis.

Aged↗
PubMed1998

Advantages and disadvantages of collaborative research: a university and behavioral health care provider's experience.

This article describes the issues involved in a collaborative research effort between a university and a behavioral health care provider. We describe the collaborative process and highlight advantages and disadvantages of such collaboration. Specific examples are used to show how the collaborative process between a university team and clinical team can integrate theory, research, and clinical practice.

Behavior Therapy↗
PubMed1998

The psychiatric clinical nurse specialist/nurse practitioner: an example of a combined role.

The purpose of this article is to provide an historical overview of the clinical nurse specialist and nurse practitioner roles in psychiatric nursing. This article is written as a follow-up to that of Dyer, Hammill, Regan-Kubinski, Yurick, & Kobert, (1997), Archives of Psychiatric Nursing, 11, 2-11, in which a new paradigm for delivering comprehensive mental and general health services is conceptualized, i.e., the psychiatric-primary care nurse practitioner role. In this article an alternative model is presented: the psychiatric clinical nurse specialist/nurse practitioner role. Similarities and differences in the two roles are discussed.

Curriculum↗
PubMed1998

A chiropractic service arrangement for musculoskeletal complaints in industry: a pilot study.

Chiropractic services are commonly used by workers with musculoskeletal problems, especially low back and neck complaints. Research into the effectiveness and cost-effectiveness of this approach is, however, difficult to design without prior pilot studies. This study followed 32 workers with these complaints attending one such service and used five measures of outcome over a 6-month period. These measured pain (VAS), disability (FLP), quality of life (SF-36), perceived benefit and satisfaction with care. Additionally, sickness costs to the companies were recorded over two years encompassing the study period. Treatment utilization was also monitored. Over half the population were chronic sufferers. The effect sizes were large for pain and for seven out of eight dimensions of the SF-36 questionnaire at 6-month follow-up, although not for disability (FLP). High levels of satisfaction and perceived improvement were reported and sickness costs to the companies fell. However, the sample size in this pilot study was small and did not include controls. We would, therefore, recommend a full cost-effectiveness study incorporating a randomized trial in this area.

Adult↗
PubMed1998

Comfort care interventions in a preimplantation genetic testing program.

The fields of human genetics and assisted reproductive technology (ART) have experienced many scientific advances over the past 50 years. The integration of these two clinical specialties has resulted in the ability to perform preimplantation genetic testing (PGT) on an embryo created through ART. This is a technology that can be used by individuals at risk for the transmission of a genetic disorder to prevent occurrence of the disorder in their child. Both the process of PGT and the life experiences that lead to the decision to use PGT stimulate many levels and types of discomfort. Holistic comfort care interventions performed by the nurse are uniquely designed to eliminate or reduce discomfort and to enable those at risk to utilize the available technologies to create healthy families.

Adult↗
PubMed1998

Development of a human gamma interferon enzyme immunoassay and comparison with tuberculin skin testing for detection of Mycobacterium tuberculosis infection.

A sensitive two-step simultaneous enzyme immunoassay (EIA) for human gamma interferon (IFN-gamma) has been developed and used as an in vitro test for human tuberculosis (TB) in comparison with tuberculin skin testing. The EIA was shown to be highly sensitive, detecting less than 0.5 IU of recombinant human IFN-gamma per ml within a linear detection range of 0.5 to 150 IU/ml. The assay was highly reproducible and specific for native IFN-gamma. In addition, the assay detected chimpanzee, orangutan, gibbon, and squirrel monkey IFN-gammas. Cross-reactions with other human cytokines or with IFN-gammas derived from mice, cattle, or Old World monkeys were not evident. The assay was used to detect TB infection by incubating whole blood overnight with human, avian, and bovine tuberculin purified protein derivatives (PPDs), as well as positive (mitogen)- and negative-control preparations. The levels of IFN-gamma in plasma supernatants were then determined. Blood from 10 tuberculin skin test-positive individuals responded predominantly to the human tuberculin PPD antigen and to a lesser extent to bovine and avian PPD antigens. By contrast, blood from 10 skin test-negative individuals showed minimal responses or no response to any of the tuberculin PPDs. Detectable levels of IFN-gamma were present in all blood samples stimulated with mitogen. In vivo tuberculin reactivity was correlated with IFN-gamma responsiveness in vitro. These results support the further study of the blood culture-IFN-gamma EIA system as an alternative to skin testing for the detection of human TB infection.

Adolescent↗
PubMed1998

Sensitivity and specificity of a gamma interferon blood test for tuberculosis infection.

SETTING: Victoria, Australia. OBJECTIVE: To determine the sensitivity and specificity of a gamma interferon (IFN-gamma) blood test for tuberculosis infection. DESIGN: Heparinised blood samples from 952 volunteers were analysed using the QuantiFERON-TB blood test. The levels of IFN-gamma in whole blood aliquots stimulated in vitro with human, avian or bovine purified protein derivative (PPD), or phytohaemagglutinin (PHA), were compared to tuberculin reactivity and clinical presentation. RESULTS: IFN-gamma (IU/ml) responses were expressed as % PPD/PHA response ratios. The proportion of responders detected by both the IFN-gamma assay and tuberculin skin test (TST) was not significantly different when the % human PPD response ratio was 15%. Using this threshold, the specificity of the IFN-gamma assay was 98% (407/417 individuals with no known exposure to tuberculosis were negative) and sensitivity was 90% (163/182 untreated TST reactors were positive). The test detected positive responses in 83% (10/12) of individuals with proven active disease, 59% (24/41) of those previously treated, 80% (134/168) of those with untreated inactive disease, and 43% (55/128) of those exposed but TST-negative. CONCLUSION: The measurement of IFN-gamma released from PPD-stimulated blood lymphocytes is a specific, sensitive and rapid method of detecting Mycobacterium tuberculosis infection. The IFN-gamma assay may be a useful and practical tool for the early diagnosis of tuberculosis infection, especially in immunocompetent individuals.

Adult↗
PubMed1998

HELLP! A cry for laboratory assistance: a comprehensive review of the HELLP syndrome highlighting the role of the laboratory.

The HELLP syndrome is a dangerously severe form of preeclampsia associated with multiorgan system damage and occurs in 0.2-0.6% of all pregnancies. It usually presents with abdominal pain, often in the setting of preeclampsia. In most cases, HELLP is initiated by inadequate placental vessel development with subsequent placental ischemia, leading to the release of circulating vasoconstrictors. These powerful vasoconstrictors include thromboxane A2, angiotensin, prostaglandin F2, and endothelin-1. The ischemic placenta also produces fewer vasodilators, such as prostacyclin, prostaglandin, E2, and nitric oxide. The ensuing imbalance in vasoactive substances causes intense systemic vasospasm and multiorgan endothelial damage. Multiple genetic, coagulation, and immunologic disorders also appear to contribute to the endothelial damage. Fibrin and platelets are then deposited on the endothelial surfaces leading to the hemolytic anemia, elevated liver enzymes, and low platelets of the HELLP syndrome. The most reliable laboratory tests for the diagnosis of HELLP are a complete blood count with peripheral smear, lactate dehydrogenase, serum transaminases, and urinalysis. Supportive tests include serum haptoglobin, D-dimer fragment levels, lactate dehydrogenase isoenzymes, total bilirubin, prothrombin times, and activated partial thromboplastin times. Lactate dehydrogenase and the platelet count are the two best tests to monitor the course of the disease. Prompt delivery is the treatment of choice. The intensity of the HELLP syndrome peaks 24 hours after delivery. Extended atypical HELLP has been successfully treated with plasma exchange. The clinical laboratory professional plays an important role in the diagnosis, follow-up, and treatment of patients with the HELLP syndrome.

Adult↗
PubMed1997

Comparison of a tuberculin interferon-gamma assay with the tuberculin skin test in high-risk adults: effect of human immunodeficiency virus infection.

A novel, whole blood interferon-gamma (IFN-gamma) assay was evaluated to determine its suitability for detecting Mycobacterium tuberculosis exposure in intravenous drug users with or without human immunodeficiency virus (HIV) infection. Whole heparinized blood was incubated overnight in separate wells with tuberculin purified protein derivative (PPD), saline, and mitogen controls. Levels of IFN-gamma in plasma supernatants were determined by rapid ELISA. Participants were then administered the tuberculin skin test (TST) and tested for cutaneous anergy. The whole blood IFN-gamma test agreed (89%-100%) with a positive TST in both HIV-seropositive and -seronegative subjects, but reactivity to PPD was more detectable by the whole blood assay among those with negative TSTs or anergy. TST induration diameter and IFN-gamma responses were correlated (Spearman's p = .45, P = .0001), but both responses were blunted by HIV infection. In summary, tuberculin reactivity appears to be more detectable by the whole blood IFN-gamma assay than by TST, and the assay requires no return visit for test reading.

Adult↗