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Biomedical subjects

N Thompson

Publications and source records attributed to N Thompson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Endocrine patterns during aging in the common tern (Sterna hirundo).

Blood samples were taken from breeding common terns (Sterna hirundo) of known age during two successive breeding seasons to determine if plasma concentrations of estradiol, progesterone, androgen, and luteinizing hormone (LH) reflect the process of aging. Males and females were trapped and sampled once between laying of the first and the second eggs in the clutch. The transient capture and sampling did not disrupt incubation or the timing of the subsequent oviposition. Ages ranged from 2 to 21 years, with most in the range 4-11 years. There was a strong inverse correlation (P < 0.0001) between age and laying date in both females and males, with older birds nesting earlier in the season. Plasma LH levels increased (P < 0.005) among mature (>5 year) females. Plasma progesterone and E2 were positively correlated with each other among mature females, but did not change in an age-dependent manner. In males, plasma progesterone levels showed no age-related changes. However, maturing (3-5 year) males showed increasing plasma androgen levels (P < 0.01); mature males showed no change with age. Plasma LH levels were correlated with androgen levels in both maturing and mature males. Plasma progesterone declined with age in maturing males (P < 0.001). These data provide evidence for changing endocrine status with age, but the patterns differ for younger individuals (</=5 year) and mature birds. It appears that in younger individuals, nesting experience and maturity of the pair affect reproductive performance and endocrine status. Individual variability was high for all hormones, possibly masking age-related changes. Only breeding individuals were sampled at all ages, although the proportion of the population that continues to reproduce may decline as the birds age. In summary, common terns continue to breed successfully until at least age 21 years and these individuals maintain relatively stable endocrine status during aging. Although there was some indication of declines in estradiol and androgens among the oldest birds (16-21 years), these declines were not statistically significant and were manifested in only a small fraction (<4%) of the breeding population.

Aging↗
PubMed1999

Cost effectiveness of EUS for preoperative localization of pancreatic endocrine tumors.

BACKGROUND: Endoscopic ultrasonography (EUS) is highly accurate in the localization of small pancreatic tumors. We determined the cost effectiveness of EUS used early in the preoperative evaluation of pancreatic endocrine tumors. METHODS: In a study with a case-control design, 36 patients (19 men, 17 women) who underwent preoperative EUS were matched retrospectively with 36 patients who underwent surgical exploration immediately before the introduction of EUS. The number, cost, and effectiveness of preoperative localization studies, days of hospitalization, and surgical and anesthesia times were assessed. RESULTS: The EUS group had reduced charges for preoperative localization studies: $2620 versus $4846 per patient (p < 0.05), largely because of reductions in the number of diagnostic angiograms and venous sampling procedures performed. Surgical and total anesthesia times were decreased, as were the number of preoperative admissions for angiographic procedures. The cost-effectiveness ratio for the EUS group was $3144 per tumor localized compared with $5628 per tumor localized for the group treated before EUS became available (p < 0.05). CONCLUSION: EUS is highly accurate in the localization of pancreatic neuroendocrine tumors and is cost effective when used early in the preoperative localization strategy. EUS decreased the need for additional invasive tests and avoided unnecessary morbidity and resource consumption. EUS should play a primary role in preoperative localization of pancreatic neuroendocrine tumors.

Angiography↗
PubMed1999

To determine whether the temperature of 2% lignocaine gel affects the initial discomfort which may be associated with its instillation into the male urethra.

OBJECTIVE: To determine whether the temperature of 2% lignocaine hydrochloride gel affects the initial discomfort during instillation into the male urethra. PATIENTS AND METHODS: Sixty consenting men were randomized to receive 11 mL of 2% lignocaine hydrochloride gel (Instillagel, Farco-Pharma GmbH, Cologne, Germany) at 4 degrees C, 22 degrees C or 40 degrees C. The three groups were well matched for age and numbers of previous flexible cystoscopies. The gel was instilled by one operator and the patients were then immediately asked to score the pain on instillation using a 100-mm nongraphical visual analogue scale. RESULTS: Compared with the control group (at 22 degrees C), there was a statistically significant reduction in pain score in the group receiving cold gel (Student's t-test, P<0.05). CONCLUSION: The cooling of 2% lignocaine gel significantly reduced the initial discomfort associated with its delivery into the male urethra before any form of urethral instrumentation.

Administration, Topical↗
PubMed1999

Perceived ownership in a community coalition.

Coalitions are emerging as a force for change in many communities and offer the opportunity for broad community involvement in the planning and implementation of needed health promotion and health education services. Perceived ownership promotes greater participation by the community but efforts to systematically evaluate ownership are lacking. The aim of this study was to determine ownership of a local ElderCARE Coalition's activities and its health promotion program, Healthy WAY, as perceived by coalition members. Fifteen of the coalition members returned the questionnaire that included the Community Ownership Scale. As shown by mean scores, the agencies perceived as having the most influence or greatest perceived ownership were the university college of nursing and the community action programs. Coalition members represented a wide variety of roles and responsibilities as well as length of time in the coalition (1 month to 6 years). Responses to open-ended questions, analyzed by content analysis, supported the work of the coalition and identified the senior participants in the Healthy WAY program as being "enthusiastic" but also needing to be more "involved." Process measures are important indicators of how close coalitions are staying to their grassroots constituency. Implications for public health nurses include participating as partners in community coalitions and assisting coalitions in determining their sense of ownership and the need for change.

Aged↗
PubMed1999

Life Options Patient Opinion Study identifies keys to a long life for dialysis patients.

Results of a recent survey of 31 people on dialysis show that, initially, most of them had no real expectation of living a long life when they started treatment. How and why have their perceptions changed? What can providers and other patients learn from this Life Options Patient Opinion Study? For people on dialysis, rehabilitation means living long and living well, despite the challenges of kidney disease. The first step to successful renal rehabilitation is ensuring that the clinical prerequisites of anemia control, adequate dialysis, a well-functioning vascular access, and proper nutrition are in place. In addition, research indicates that people on dialysis are more likely to experience positive outcomes and better quality of life when they are informed about their disease and its treatments; have solid support systems; exercise regularly and remain active and productive, and engage in self-care. It is the combination of good clinical care plus rehabilitation management that can help dialysis patients return to active and fulfilling lives. In 1993 the Life Options Rehabilitation Advisory Council (LORAC) developed a comprehensive approach to renal rehabilitation, based on the "5E's:" Encouragement, Education, Exercise, Employment, and Evaluation. Since then, the 5E's have served as the basis for numerous activities of the Life Options Rehabilitation Program. The Patient Opinion Study examined the patient experience as a way to begin identifying the keys to a long life on dialysis.

Activities of Daily Living↗
PubMed1998

Phospholipase D1 localises to secretory granules and lysosomes and is plasma-membrane translocated on cellular stimulation.

Phospholipase D (PLD) activity has been implicated in the regulation of membrane trafficking [1,2], superoxide generation and cytoskeletal remodelling [3,4]. Several PLD genes have now been identified and it is probable that different isoforms regulate distinct functions. Defining the subcellular localisation of each isoform would facilitate understanding of their roles. Previous PLD localisation studies have been based largely on enzyme activity measurements, which cannot distinguish between isoforms [2,5]. We have cloned the cDNAs encoding human PLD1a and PLD1b from an HL60 cell cDNA library and expressed them as catalytically active fusion proteins with green fluorescent protein (GFP) in COS-1 cells and RBL-2H3 cells, a mast cell model which degranulates upon cross-linking of the high-affinity immunoglobulin E (IgE) receptor. In unstimulated cells, GFP-PLD1b colocalised with secretory granule and lysosomal markers; it was not found at the plasma membrane or nucleus and did not colocalise with markers for the Golgi. Stimulation or RBL-2H3 cells through IgE receptor cross-linking caused plasma membrane recruitment of GFP-PLD1b. Inhibition of IgE-receptor-stimulated, PLD-catalysed phosphatidate formation suppressed secretion of granule and lysosomal contents, but did not affect translocation of GFP-PLD1b. These experiments suggest that PLD1 plays a role in regulated exocytosis rather than endoplasmic reticulum (ER) to Golgi membrane transport.

Animals↗
PubMed1998

RAMPs regulate the transport and ligand specificity of the calcitonin-receptor-like receptor.

Calcitonin-gene-related peptide (CGRP) and adrenomedullin are related peptides with distinct pharmacological profiles. Here we show that a receptor with seven transmembrane domains, the calcitonin-receptor-like receptor (CRLR), can function as either a CGRP receptor or an adrenomedullin receptor, depending on which members of a new family of single-transmembrane-domain proteins, which we have called receptor-activity-modifying proteins or RAMPs, are expressed. RAMPs are required to transport CRLR to the plasma membrane. RAMP1 presents the receptor at the cell surface as a mature glycoprotein and a CGRP receptor. RAMP2-transported receptors are core-glycosylated and are adrenomedullin receptors.

3T3 Cells↗
PubMed1998

Parental anxiety before elective surgery in children. A British perspective.

This study measures the anxiety levels in 100 parents of children scheduled for elective surgery at the Royal Aberdeen Children's Hospital. Anxiety levels were quantified using the Leeds scale for self-assessment of anxiety. Forty-two per cent of parents were significantly anxious. Mothers were identified as being more pathologically anxious than fathers. The 'anxious' parents were specifically more anxious about the surgery, anaesthesia, postoperative pain and treatment, and hospitalisation in general. All parents, whether identified as anxious or not, agreed on factors likely to reduce anxiety: pre-operative information from staff, being able to accompany their child to the operating theatre and being present at induction of anaesthesia.

Adolescent↗
PubMed1998

Intra-articular injection of ketorolac in the rat knee joint: effect on articular cartilage and synovium.

We have investigated the effects of intra-articular (i.a.) administration of ketorolac in the rat knee joint. Thirty Sprague-Dawley rats were given 0.25 ml of a standard preparation of ketorolac trometamol (10 mg ml-1) by injection into the right knee joint and 0.25 ml of 0.9% physiological saline solution by injection into the left knee as a control. Ten rats were killed at 24 h, 10 at 48 h and 10 at 5 days after injection. The joints were prepared and sectioned for histological examination. There was significantly more inflammation in those knees that had received i.a. ketorolac at all times of examination, with the most severe changes occurring 5 days after injection. A further group of 10 rats were given 0.25 ml of 10% w/v ethanol in physiological saline (similar to the vehicle for parenteral ketorolac) injected into the knee joint, with a 0.9% saline control injected in the other knee. These rats were then killed at 5 days (as this was the time interval after which we found the maximum inflammatory response in the earlier phase of our study). The joints were prepared and examined histologically. We feel that the absence of inflammatory changes in these joints make it unlikely that ethanol was responsible for the inflammation produced by ketorolac injection.

Analgesics↗
PubMed1998

Transcriptional activation of the macrophage migration-inhibitory factor gene by the corticotropin-releasing factor is mediated by the cyclic adenosine 3',5'- monophosphate responsive element-binding protein CREB in pituitary cells.

Macrophage migration-inhibitory factor (MIF) has recently been identified as a pituitary hormone that functions as a counterregulatory modulator of glucocorticoid action within the immune system. In the anterior pituitary gland, MIF is expressed in TSH- and ACTH-producing cells, and its secretion is induced by CRF. To investigate MIF function and regulation within pituitary cells, we initiated the characterization of the MIF 5'-regulatory region of the gene. The -1033 to +63 bp of the murine MIF promoter was cloned 5' to a luciferase reporter gene and transiently transfected into freshly isolated rat anterior pituitary cells. This construct drove high basal transcriptional activity that was further enhanced after stimulation with CRF or with an activator of adenylate cyclase. These transcriptional effects were associated with a concomitant rise in ACTH secretion in the transfected cells and by an increase in MIF gene expression as assessed by Northern blot analysis. A cAMP-responsive element (CRE) was identified within the MIF promoter region which, once mutated, abolished the cAMP responsiveness of the gene. Using this newly identified CRE, DNA-binding activity was detected by gel retardation assay in nuclear extracts prepared from isolated anterior pituitary cells and AtT-20 corticotrope tumor cells. Supershift experiments using antibodies against the CRE-binding protein CREB, together with competition assays and the use of recombinant CREB, allowed the detection of CREB-binding activity with the identified MIF CRE. These data demonstrate that CREB is the mediator of the CRF-induced MIF gene transcription in pituitary cells through an identified CRE in the proximal region of the MIF promoter.

Animals↗
PubMed1998

Food consumption patterns of Inuit women.

To evaluate nutrient intake and food consumption patterns of Inuit women of child-bearing age, a 24-hour diet recall and general health and food frequency questionnaire was administered to 688 Inuit women aged 15-44 in six isolated communities. Data were analyzed using the 1991 Canadian Nutrient File. Mean intakes of essential nutrients were expressed as percentages of Health Canada's 1990 Recommended Nutrient Intakes (RNI). Chi-square tests were used to determine relationships between categorical variables. Folacin intake ranged from 49% to 95% of the RNI in most communities (median = 76%) and was only 37% of the RNI for pregnant and 54% for lactating women. Mean calcium intake for pregnant and lactating women averaged 55% and 47% of the RNI, respectively. Average vitamin A intakes ranged from 26% to 87% of the RNI (median = 65%), with intake for pregnant Inuit women and lactating women 79% and 54% of the RNI, respectively. Country food was the major source of protein and iron, and store foods the major source of calories, calcium, folacin, and vitamin A. Low intakes of folacin, calcium, and vitamin A, especially among pregnant and lactating women, place Inuit women of childbearing age at risk. Women on social assistance are nutritionally vulnerable.

Adolescent↗
PubMed1997

Insulin secretion is regulated by the glucose-dependent production of islet beta cell macrophage migration inhibitory factor.

Macrophage migration inhibitory factor (MIF), originally identified as a cytokine secreted by T lymphocytes, was found recently to be both a pituitary hormone and a mediator released by immune cells in response to glucocorticoid stimulation. We report here that the insulin-secreting beta cell of the islets of Langerhans expresses MIF and that its production is regulated by glucose in a time- and concentration-dependent manner. MIF and insulin colocalize by immunocytochemistry within the secretory granules of the pancreatic islet beta cells, and once released, MIF appears to regulate insulin release in an autocrine fashion. In perifusion studies performed with isolated rat islets, immunoneutralization of MIF reduced the first and second phase of the glucose-induced insulin secretion response by 39% and 31%, respectively. Conversely, exogenously added recombinant MIF was found to potentiate insulin release. Constitutive expression of MIF antisense RNA in the insulin-secreting INS-1 cell line inhibited MIF protein synthesis and decreased significantly glucose-induced insulin release. MIF is therefore a glucose-dependent, islet cell product that regulates insulin secretion in a positive manner and may play an important role in carbohydrate metabolism.

Animals↗
PubMed1997

Rat basophilic leukaemia (RBL) cells overexpressing Rab3a have a reversible block in antigen-stimulated exocytosis.

The rat basophilic leukaemia (RBL) cell line has been widely used as a convenient model system to study regulated secretion in mast cells. Activation of these cells through the high-affinity receptor for IgE (Fcepsilon-RI) results in degranulation and the extracellular release of mediators. There is good evidence of a role for GTPases in mast cell degranulation, and a number of studies with peptides derived from the Rab3a effector domain have suggested that Rab3a may function in this process. However, in neuroendocrine cells, overexpression of Rab3a can act as a negative regulator of stimulated exocytosis [Holz, Brondyk, Senter, Kuizon and Macara (1994) J. Biol. Chem. 269, 10229-10234; Johanes, Lledo, Roa, Vincent, Henry and Darchen (1994) EMBO J. 13, 2029-2037]. In order to study the function of Rab3a in RBL degranulation, we have generated clones of RBL cells stably expressing Rab3a, and show that in these haematopoietic cells Rab3a can also function as a negative regulator of exocytosis. Overexpression of a mutant form of Rab3a (Asn-135 to Ile), which is predicted to be predominantly GTP-bound, also inhibited degranulation. However, overexpression of a mutant form of Rab3a that was truncated at the C-terminus to remove the sites for geranylgeranylation failed to inhibit degranulation. The effect of Rab3a is specific to secretion, and we observe no effect of Rab3a on receptor-mediated endocytosis. The Rab3a-induced block in degranulation can be bypassed by stimulation of streptolysin-O-permeabilized cells with guanosine 5'-[gamma-thio]triphosphate. We conclude from these studies that Rab3a is implicated in an early stage of granule targeting, whereas fusion of granules with the plasma membrane is regulated by a distinct downstream GTP-binding protein or proteins.

Animals↗
PubMed1997

Neuroendocrine regulation of GnRH and behavior during aging in birds.

Avian species exhibit a great variety of life-long patterns in reproduction. Japanese quail are relatively short lived and undergo an age-related loss of reproductive function, making this species an excellent model for the study of the basic biology of aging. Because individuals age at variable rates, sexual behavior has provided a useful index to assess reproductive status of individuals of the same chronological age. Further, exogenous testosterone restores sexual behavior in reproductively senescent male quail, thereby providing evidence for a continued ability of the system to respond. In addition, we have been studying hypothalamic neuroendocrine systems that regulate the endocrine as well as behavioral components of reproduction. Overall, our findings point to the hypothalamic neuroendocrine systems as the site of initial age-related alterations that contribute to the reproductive deterioration. Specifically, we studied adrenergic, opioid peptide, vasotocin, and aromatase systems to understand their relationship to the cGnRH-I system and their potential role in the deterioration of the cGnRH-I system during aging. Our findings provide evidence for qualitative and quantitative alterations in the aromatase enzyme system, which can be partially restored with exogenous testosterone. In addition, other neuronal systems, including the vasotocin system, decline with the loss of gonadal steroids and are restimulated with exogenous testosterone. We will synthesize the data relative to these neuroendocrine systems with attention to the effects of gonadal steroids on these systems during aging.

Aging↗
PubMed1997

Patient-maintained propofol sedation. Assessment of a target-controlled infusion system.

We have developed a system which allows patients to operate a target-controlled infusion of propofol to provide sedation and we have studied its use in 36 unpremedicated patients undergoing local and regional anaesthetic procedures lasting 10-280 min. An intravenous propofol infusion was started at a target plasma level of 1 microgram.ml-1. The patient was able to increase the target propofol concentration in 0.2- microgram.ml-1 increments by pressing a demand button. There was a lockout interval of 2 min and a maximum permissible target concentration of 3 micrograms.ml-1. There was considerable interindividual variability in propofol consumption (mean 39.3 micrograms.kg-1.min-1, range 3-131 micrograms.kg-1.min-1), no cardiovascular instability and little oversedation. Eight patients required supplementary oxygen. Optimal sedation was provided at median target concentrations of 0.8-0.9 microgram.ml-1. The target-controlled infusion system bias was-47% and the inaccuracy was 48%. Patient satisfaction was high and 89% said that they would definitely use the technique again. This technique combines the benefits of target-controlled infusion with patient-controlled feedback and produces safe intra-operative sedation.

Adult↗