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Biomedical subjects

S Cummings

Publications and source records attributed to S Cummings.

At least 55 records · Page 3Linked to original sources
PubMed1990

Blood culture phlebotomy: switching needles does not prevent contamination.

OBJECTIVE: To determine how switching to a sterile needle after phlebotomy and before the inoculation of blood culture bottles affects the rate of skin flora contamination. DESIGN: A randomized trial. SETTING: Medical inpatient services and the emergency department of a large university hospital. PARTICIPANTS: Housestaff, medical students, nurses, and physician assistants who draw blood cultures on the general medicine, cardiology, and renal transplant units and in the emergency department. INTERVENTIONS: Phlebotomists were randomly assigned to draw blood cultures by either the conventional method or an alternative method in which the blood culture bottles were inoculated without switching needles. MEASUREMENTS AND MAIN RESULTS: There was no difference in the rate of contamination between the conventional technique (6 of 462 cases, 1.30%) and the alternative technique (7 of 451 cases, 1.55%) (95% CI for the difference in rates, -1.8% to 1.2%). CONCLUSIONS: The needle switch in the conventional blood culture technique does not reduce the rate of skin flora contamination. Blood cultures should no longer be obtained by switching needles.

Blood Specimen Collection↗
PubMed1990

Coexistence of corticotropin releasing factor and enkephalin in cerebellar afferent systems.

In this study, we tested the hypothesis that corticotropin-releasing factor (CRF) and enkephalin (ENK) coexist within restricted brainstem-cerebellar circuits. Antisera for CRF and ENK were applied simultaneously or to serial sections of adult opossum brain and were processed for fluorescence or peroxidase, antiperoxidase immunohistochemistry, respectively. CRF and ENK were colocalized in 1) climbing fibers within the flocculus and in bilateral foci in the cerebellar vermis; 2) fibers with morphological characteristics of simple mossy fiber terminals or climbing fiber glomeruli that were located within the granule cell layer of the vermis underlying the foci of CRF/ENK-IR climbing fibers; 3) mossy fiber terminals within the flocculus; 4) neuronal perikarya in subnucleus A and C of the medial accessory olive and in the dorsal cap of Kooy, nuclei known to project as climbing fibers; and 5) cell bodies in nucleus prepositus, the subtrigeminal reticular nucleus, and the reticular formation, likely origins of CRF/ENK colocalized mossy fibers. The demonstration that single climbing and mossy fibers contain two peptides extends previous studies that have described chemical heterogeneity within cerebellar afferent pathways. Furthermore, these results support suggestions that this heterogeneity may provide a substrate for differential regulation of signal transduction by chemically coded cerebellar afferents.

Animals↗
PubMed1988

Relationship of alpha-1- and alpha-2-adrenergic-binding sites to regions of the paraventricular nucleus of the hypothalamus containing corticotropin-releasing factor and vasopressin neurons.

To investigate catecholamine regulation of adrenocorticotropic hormone (ACTH) and vasopressin (VP) release, the relationship of alpha-adrenergic receptor-binding sites to corticotropin-releasing factor (CRF) and VP-containing cell populations within the paraventricular nucleus (PVN) of the hypothalamus was studied. Immunohistochemistry for CRF and neurophysin-vasopressin (NP-VP) was combined with receptor autoradiography. The adrenergic antagonist [3H]-prazosin was used to visualize alpha-1-binding sites and the agonist [3H]-p-aminoclonidine to visualize alpha-2-binding sites. To determine if changes in adrenergic binding accompanied experimentally induced increased activity of CRF- and VP-containing neurons, adrenalectomy was used as a stimulus for CRF release and dehydration as a stimulus for VP release. Quantitative assessment of autoradiograms revealed a greater density of alpha-1- and alpha-2-binding sites over the medial, parvocellular, CRF-containing region of PVN as compared to the lateral, magnocellular, NP-VP-containing region of the nucleus in all animal groups. Following 10 days of dehydration, the density of alpha-1- and alpha-2-binding sites associated with the CRF- and NP-VP-containing regions of PVN decreased. At 14 days postadrenalectomy the density of alpha-2-binding sites associated with CRF- and NP-VP-containing regions of the nucleus decreased, but the density of alpha-1-binding sites was unchanged. Results of this study support the hypothesis that epinephrine and/or norepinephrine regulate the release of ACTH and vasopressin via alpha-1- and alpha-2-adrenergic receptors associated with CRF- and VP-containing somata within the PVN.

Adrenergic alpha-Agonists↗
PubMed1988

Corticotropin-releasing factor in cerebellar afferent systems: a combined immunohistochemistry and retrograde transport study.

The flocculus and paraflocculus of cat and sheep cerebellum were studied with immunohistochemical methods, using antisera to corticotropin-releasing factor (CRF). CRF immunoreactivity was present within 3 populations of varicose nerve fibers. One population of CRF-immunoreactive (CRF-IR) fibers appeared to appose Purkinje cell somata and to follow their dendrites into the molecular layer. This arrangement suggested they were climbing fibers. A second group of CRF-IR profiles reminiscent of mossy fibers was widely distributed throughout the granule cell layer. A third population of CRF-IR fibers was present as a beaded plexus lying parallel to the pial surface, above and subadjacent to the Purkinje cell layer. The fibers of this plexus extended into the Purkinje cell layer and surrounded these somata. The source of some of the CRF-IR fibers within the flocculus and paraflocculus was determined by a retrograde axonal transport study utilizing the fluorescent tracer Fast blue (FB) in combination with the immunohistochemical localization of CRF. It was determined that CRF-IR perikarya within the inferior olivary nucleus gave rise to a population of climbing fibers within those lobules. Furthermore, all divisions of the inferior olive were found to contain CRF-IR somata. This latter finding suggests the potential for CRF-IR climbing fiber projections from the inferior olive to other regions of the cerebellar cortex. The existence of CRF-IR mossy fibers and fibers within the ganglionic plexus suggests the possibility of CRF-IR afferent projections from other regions of the brain stem to the flocculus and paraflocculus.

Afferent Pathways↗
PubMed1987

Distribution of nicotinic binding sites with respect to CRF and neurophysin immunoreactive perikarya within the rat hypothalamus.

These studies determined the differential autoradiographic distribution of [125I]alpha-bungarotoxin versus [3H]nicotine relative to the histochemically defined perikarya for neurophysin and corticotropin releasing factor (CRF). Specific [3H]nicotine binding sites occurred in relatively greater density within the neuropil surrounding PVN and SON compared to within the nuclei. In contrast, the highest density of [125I]alpha-BTX sites codistributed with neurophysin immunoreactive perikarya within these nuclei.

Animals↗
PubMed1986

Acute hemodynamic and hormonal effects of lisinopril (MK-521) in congestive heart failure.

The acute hemodynamic and hormonal effects of the oral angiotensin-converting enzyme (ACE) inhibitor lisinopril (MK-521) were assessed over a period of 96 hours in 12 patients with heart failure. This compound is the lysine analogue of enalaprilat (MK-422), is biologically active following absorption, and is cleared via the urine without any known metabolic transformation. Single doses of lisinopril, ranging from 1.25 mg to 10 mg, were administered on days 1 and 3, each followed by 48 hours of intensive hemodynamic observation. Across all doses, maximal reductions in mean arterial pressure (17.2%), mean pulmonary capillary wedge pressure (28%), and systemic vascular resistance (25.6%) were observed compared to baseline values. No significant changes in heart rate were recorded. Arterial blood was sampled at frequent intervals for angiotensin II, ACE activity, plasma renin activity, renin substrate, plasma aldosterone, and serum drug levels. Right atrial blood was sampled simultaneously for angiotensin I, thus permitting assessment of the degree of pulmonary conversion to angiotensin II. The results indicate potent inhibition of the renin-angiotensin-aldosterone system along with hemodynamic efficacy over a period exceeding 24 hours. Frequent clinical follow-up on long-term chronic therapy has revealed no adverse experience.

Adult↗
PubMed1985

The predictive value of physical examinations for ascites.

To determine the predictive value of physical signs for ascites, we compared the results of physical examination with those of abdominal sonography in 90 men in hospital with liver disease. The positive predictive values of shifting dullness and prominent fluid waves were low (51% and 73%). We divided the patients into two groups: those with prolonged prothrombin times (72% prevalence of ascites by sonogram), and those with normal prothrombin times (15% prevalence). In patients with prolonged prothrombin times, a prominent fluid wave had a very high positive predictive value for ascites (96%). Many patients with prolonged prothrombin times had ascites despite negative physical signs. In contrast, in those with normal prothrombin times, both shifting dullness and prominent fluid waves were usually falsely positive. Patients with normal prothrombin times and no shifting dullness rarely (2%) had ascites. The predictive value of physical signs for ascites depends on the prevalence of ascites in groups of patients that are examined. The prothrombin time is a useful index for identifying inpatients with a high or low prevalence of ascites and the predictive value of physical signs is enhanced by interpreting them in combination with a patient's prothrombin time.

Ascites↗
PubMed1984

Peptidergic regulation in neuroendocrine and autonomic systems.

Neuropeptides are found in dense networks of neuronal perikarya, fibers and terminals within numerous brain regions. Among the more striking of these collections are sites within the central nervous system that are presumed to regulate either endocrine or autonomic function. A recent example of a neuropeptide which is likely to play a significant role in endocrine regulation is cortocotropin releasing factor (CRF). Immunohistochemical studies revealed that CRF immunoreactivity was found in many brain regions, including the paraventriculo-infundibular pathway. CRF released from nerve terminals belonging to this pathway presumably regulates ACTH release. Treatment of rats with reserpine depletes CRF as well as vasopressin from the external layer of the median eminence, suggesting tonic, monoaminergic inhibition of CRF and vasopressin containing neurons. CRF antisera were found which stain urotensin I immunoreactivity within the caudal neurosecretory system of fish. Numerous putative neurotransmitters impinge upon preganglionic sympathetic neurons within the intermediolateral cell column of the spinal cord. Preganglionic sympathetic neurons which innervate the adrenal medulla appear to have a specific input from somatostatin immunoreactive fibers. In addition, binding sites for serotonin and alpha-2 adrenergic ligands are more highly concentrated over sympathoadrenal neurons. Finally, the pancreatic islet contains peptide producing endocrine cells which possess several neuron-like properties. Some of these properties are reviewed, especially the finding that the insulin producing cells contain glutamate decarboxylase immunoreactivity, the biosynthetic enzyme for GABA. Further studies revealed that GABA agonists inhibit somatostatin release from islet cells.

Adrenal Medulla↗
PubMed1983

Corticotropin-releasing factor immunoreactivity is widely distributed within the central nervous system of the rat: an immunohistochemical study.

The discovery of a 41-amino acid peptide with potent corticotropin-releasing factor properties has prompted a search for neurons that contain this substance and potentially utilize it in intercellular communication. The present study utilized immunohistochemical methods and an antiserum directed against a synthetic replica of ovine corticotropin-releasing factor. The rat hypothalamus was found to contain striking immunoreactive groups of neuronal perikarya within the paraventricular, periventricular, and anterior hypothalamic nuclei, some of which are likely to project to the external layer of the median eminence and thereby comprise a hypophysiotropic system. Certain other hypothalamic nuclei, as well as many other regions of the central nervous system, were found to contain corticotropin-releasing factor-immunoreactive neurons. Among the most prominent of these were neurons in the bed nucleus of stria terminalis, the central nucleus of the amygdala, the region of the dorsal raphe, locus ceruleus, the external cuneate nucleus, and the medullary reticular formation. Thus, corticotropin-releasing factor, like many other neurohormones and peptides, may participate in neuroendocrine regulation as well as play a role as a neurotransmitter-like substance in numerous extrahypothalamic circuits.

Animals↗
PubMed1980

Effect of proline on synthesis of collagen by cells in culture.

Chick embryo cells, human epithelial cells, and mouse cells in culture were tested for response to elevated levels of proline in the growth medium. In none of the cell lines tested was the amount of collagen formed stimulated by addition of excess proline.

Animals↗
PubMedDate not supplied

Transitions out of high school: time of increased cancer risk?

BACKGROUND: The effectiveness of lifestyle behavior interventions with children to reduce chronic disease risks in adulthood assumes stability in the lifestyle behaviors across time. The transition out of high school is a time when many changes occur in social roles, e.g., changing schools, leaving the parents' home, changing peers, finding employment, getting married, and becoming a parent. Cancer risk behaviors may increase as a result of some of these social role changes. METHODS: Concepts relevant to the stability or change in lifestyle behaviors through the transition out of high school are presented. Literature concerning diet, smoking, smokeless tobacco, alcohol, physical activity, sexual practices, and sun exposure behaviors through the transition is reviewed. RESULTS: Most lifestyle behaviors display increasing cancer risk around the transition out of high school. Different levels of change were associated with different pathways through the transition. Inconsistent findings were obtained in the pattern of co-occurrence of these behaviors. CONCLUSION: Priority research includes establishing the pattern of co-occurrence of lifestyle behaviors through the transition, identifying the pattern of tracking of each behavior through the transition, and identifying the primary influences on the group values and tracking of the behaviors. Longitudinal research is needed to control for preexisting differences between pathways through the transition.

Adolescent↗