Biomedical subjects

Michael Patterson

Publications and source records attributed to Michael Patterson.

26 records · Page 2Linked to original sources

PubMed2004

Peripheral oxyntomodulin reduces food intake and body weight gain in rats.

Oxyntomodulin (OXM) is a circulating gut hormone released post prandially from cells of the gastrointestinal mucosa. Given intracerebroventricularly to rats, it inhibits food intake and promotes weight loss. Here we report that peripheral (ip) administration of OXM dose-dependently inhibited both fast-induced and dark-phase food intake without delaying gastric emptying. Peripheral OXM administration also inhibited fasting plasma ghrelin. In addition, there was a significant increase in c-fos immunoreactivity, a marker of neuronal activation, in the arcuate nucleus (ARC). OXM injected directly into the ARC caused a potent and sustained reduction in refeeding after a fast. The anorectic actions of ip OXM were blocked by prior intra-ARC administration of the glucagon-like peptide-1 (GLP-1) receptor antagonist, exendin(9-39), suggesting that the ARC, lacking a complete blood-brain barrier, could be a potential site of action for circulating OXM. The actions of ip GLP-1, however, were not blocked by prior intra-ARC administration of exendin(9-39), indicating the potential existence of different OXM and GLP-1 pathways. Seven-day ip administration of OXM caused a reduction in the rate of body weight gain and adiposity. Circulating OXM may have a role in the regulation of food intake and body weight.

Animals↗

PubMed2004

Patterns of lateral neck metastasis in papillary thyroid carcinoma.

BACKGROUND: Although lymphatic metastasis does not affect overall survival for patients with differentiated thyroid carcinoma, locoregional control can be improved with cervical lymphadenectomy. The major morbidity of neck dissection (ND) for the management of regional metastases is spinal accessory (cranial nerve XI) dysfunction. To avoid this complication, some surgeons have advocated a limited ND. OBJECTIVE: To establish the patterns of lateral cervical metastases in differentiated thyroid carcinoma and the role of comprehensive ND, we performed a review of our experience with comprehensive ND. STUDY DESIGN: Retrospective chart review. PATIENTS AND METHODS: Between 1997 and 2002, a total of 39 consecutive patients (31 women and 8 men) underwent 44 NDs for the management of lateral cervical metastases. Preoperative cytologic analysis revealed papillary carcinoma in all 39 patients (100%). All specimens were labeled and mapped by the operating surgeon to identify each level. The incidence of positive disease was determined in relation to the extent of lymphadenectomy for all dissected levels. RESULTS: All patients underwent ND at levels II through V; 7 (17%) of the 44 ND specimens included level I nodes. The incidence of metastatic disease in level II nodes was 52% (23/44 specimens). Similarly, 25 specimens (57%) contained histologic metastases at level III. Metastatic disease was noted in 18 level IV nodes (41%) and 9 level V nodes (21%). One (14%) of the 7 specimens with level I nodes contained tumor. CONCLUSIONS: Cervical metastases from papillary thyroid carcinoma occur in predictable patterns, with disease commonly present at levels II through V. We believe that a comprehensive ND, including removal of transverse cervical and spinal accessory nodes, is necessary for the complete clearance of lateral metastases.

Adolescent↗

PubMed2003

MHC-based fiber type and E-C coupling characteristics in mechanically skinned muscle fibers of the rat.

In this study, we investigated whether the previously established differences between fast- and slow-twitch single skeletal muscle fibers of the rat, in terms of myosin heavy chain (MHC) isoform composition and contractile function, are also detectable in excitation-contraction (E-C) coupling. We compared the contractile responsiveness of electrophoretically typed, mechanically skinned single fibers from the soleus (Sol), the extensor digitorum longus (EDL), and the white region of the sternomastoid (SM) muscle to t-system depolarization-induced activation. The quantitative parameters assessed were the amplitude of the maximum depolarization-induced force response (DIFR(max); normalized to the maximum Ca(2+)-activated force in that fiber) and the number of responses elicited until the force declined by 75% of DIFR(max) (R-D(75%)). The mean DIFR(max) values for type IIB EDL and type IIB SM fibers were not statistically different, and both were greater than the mean DIFR(max) for type I Sol fibers. The mean R-D(75%) for type IIB EDL fibers was greater than that for type I Sol fibers as well as type IIB SM fibers. These data suggest that E-C coupling characteristics of mechanically skinned rat single muscle fibers are related to MHC-based fiber type and the muscle of origin.

Animals↗

PubMed2003

Distinct distribution of specific members of protein 4.1 gene family in the mouse nephron.

BACKGROUND: Protein 4.1 is an adapter protein that links the actin cytoskeleton to various transmembrane proteins. These 4.1 proteins are encoded by four homologous genes, 4.1R, 4.1G, 4.1N, and 4.1B, which undergo complex alternative splicing. Here we performed a detailed characterization of the expression of specific 4.1 proteins in the mouse nephron. METHODS: Distribution of renal 4.1 proteins was investigated by staining of paraformaldehyde-fixed mouse kidney sections with antibodies highly specific for each 4.1 protein. Major 4.1 splice forms, amplified from mouse kidney marathon cDNA, were expressed in transfected COS-7 cells in order to assign species of known exon composition to proteins detected in kidney. RESULTS: A 105 kD 4.1R splice form, initiating at ATG-2 translation initiation site and lacking exon 16, but including exon 17B, was restricted to thick ascending limb of Henle's loop. A 95 kD 4.1N splice form, lacking exons 15 and 17D, was expressed in either descending or ascending thin limb of Henle's loop, distal convoluted tubule, and all regions of the collecting duct system. A major 108 kD 4.1B splice form, initiating at a newly characterized ATG translation initiation site, and lacking exons 15, 17B, and 21, was present only in Bowman's capsule and proximal convoluted tubule (PCT). There was no expression of 4.1G in kidney. CONCLUSION: Distinct distribution of 4.1 proteins along the nephron suggests their involvement in targeting of selected transmembrane proteins in kidney epithelium and, therefore, in regulation of specific kidney functions.

Animals↗

PubMed2003

Oxyntomodulin suppresses appetite and reduces food intake in humans.

Oxyntomodulin (OXM) is released from the gut postprandially, in proportion to energy intake, and circulating levels of OXM are elevated in several conditions associated with anorexia. Central injection of OXM reduces food intake and weight gain in rodents, suggesting that OXM signals food ingestion to hypothalamic appetite-regulating circuits. We investigated the effect of iv OXM (3.0 pmol/kg.min) on appetite and food intake in 13 healthy subjects (body mass index, 22.5 +/- 0.9 kg/m(2)) in a randomized, double-blind, placebo-controlled, cross-over study. Infusion of OXM significantly reduced ad libitum energy intake at a buffet meal (mean decrease, 19.3 +/- 5.6%; P < 0.01) and caused a significant reduction in scores for hunger. In addition, cumulative 12-h energy intake was significantly reduced by infusion of OXM (mean decrease, 11.3 +/- 6.2%; P < 0.05). OXM did not cause nausea or affect food palatability. Preprandial levels of the appetite-stimulatory hormone, ghrelin, were significantly suppressed by OXM (mean reduction, 44 +/- 10% of postprandial decrease; P < 0.0001). Elevated levels of endogenous OXM associated with disorders of the gastrointestinal tract may contribute to anorexia.

Adult↗

PubMed2002

Ethical dilemmas and human rights considerations arising from the evaluation of a smoking policy in a health promoting setting.

One of the key challenges in managing the Health Promoting Workplace is the development of an effective policy for the control of environmental tobacco smoke (ETS). This paper explores the ethical consequences raised when the implementation of such a policy was evaluated in a large multi-campus university. In a three-stage evaluation, the first stage involved a qualitative enquiry with the Health and Safety Committee to obtain the management perspective on the working of the policy. A survey of the perception of the ETS policy and smoking behaviours with a representative sample of staff and students constituted the second stage. In the final stage the Health and Safety Committee was engaged with the findings of stages 1 and 2 to develop a response to the evaluation. The ethical implications which arise from this evaluation centre, firstly, on the underlying reasons for undertaking an evaluation. Secondly, consideration is given to the consequences of applying utilitarian principles to smoking policy for the minority who smoke and thus find their work or study patterns affected by a smoking ban. Such a ban limits their autonomy and while it may be helpful (beneficent) in terms of their longer-term physical health, it may have harmful (maleficent) effects on their psychological wellbeing and the potential for negative consequences if they choose to contravene the ban on smoking. The implications of addressing this situation are explored.

Adolescent↗

PubMedDate not supplied

Peptide YY (PYY) is increased in elderly patients with femoral neck fractures: a prospective cohort study.

BACKGROUND: Peptide YY (PYY), a gut peptide, has recently been shown to inhibit appetite. The role of this peptide in elderly nutritionally-compromised patients with femoral neck fracture (FNF) has not been investigated. In this study, we investigated the longitudinal pattern of PYY levels during hospital stay and investigated the postprandial PYY response to a standard meal in patients with FNF and matched controls. METHODS: Fasting plasma concentrations of the PYY were measured on days 1, 4, 7, 14, 21 and 28 or on discharge from the hospital in 17 white patients with FNF. On the second week of stay, 13 patients with FNF consumed a standard breakfast following an overnight fasting. One fasting sample and one 45-minute postmeal sample were collected. A control group was made up of 17 matched healthy elderly patients. RESULTS: PYY concentrations were increased significantly over the length of hospital stay. Results of the test breakfast suggested a significant and exaggerated post-prandial PYY response, despite a smaller energy intake being consumed. CONCLUSIONS: This study shows PYY concentrations are increased during hospitalization and their post-prandial release exaggerated in this group of vulnerable patients, and suggests a role in the etiology of reduced appetite in this patient group.

Aged, 80 and over↗

PubMedDate not supplied

Predictors of successful relationships in a peer support program for Alzheimer's caregivers.

This study explores the role of similarity in the success of peer support relationships in an intervention program for dementia caregivers. Hypothesized predictors of successful matches included structural similarity between partners (e.g., in age, education), appraisal similarity (e.g., in satisfaction with support for caregiving), and psychological similarity (e.g., in psychological well-being). Contrary to expectations, no relationship between these types of similarity and the success of the match were found, but effects were found for dissimilar pairs on several characteristics. The findings suggest: 1) that what really makes a difference for successful peer support is sharing the stressful but also rewarding experience of caregiving; and 2) that program planners do not need to develop extensive matching criteria.

Adult↗