In vitro biocompatibility study of electrically conductive polypyrrole-coated polyester fabrics

This study investigated the basic biocompatibility aspects of two types of polypyrrole (PPy)-coated polyester fabrics for possible use as vascular prostheses. These PPy-coated fabrics, PPy-Phos and PPy-Plas, were sterilized with ethylene oxide (EO) and the following characterizations were performed: surface morphology by scanning electron microscope, EO residuals analysis by the headspace method, acute systemic toxicity in the mouse model, hemolysis, blood coagulation time, viability and proliferation of endothelial cells measured with the WST-1 method, and activation of polymorphonuclear (PMN) cells indicated by the specific expression of interleukin 8 mRNA measured by reverse transcription polymerase chain reaction. Virgin polyester fabrics, expanded poly(tetrafluoroethylene) (ePTFE), and medical-grade Bionate 80A poly(carbonate urethane) were used as references in the cell culture experiments. The PPy-coated fabrics revealed different surface morphologies by showing more PPy lamina and clusters on the PPy-Plas. Neither of the PPy-coated fabrics had an adverse effect on hemolysis and coagulation time, and they did not cause any acute systemic toxicity. The EO residual level was as low as 5 ppm or less, which is considered quite acceptable. Although exhibiting a relatively low initial cell adhesion at 24 h, the two PPy-coated samples showed no cytotoxicity at 72 and 168 h. Bionate 80A and ePTFE recorded cytotoxicity at 72 and 168 h, respectively. The virgin fabrics also demonstrated a decrease of viable cells at 72 h that was not significant. The activation of PMN cells induced by both PPy-coated fabrics, the ePTFE, and the negative control was significantly lower than that induced by their respective tumor necrosis factor-alpha controls. These results therefore highlighted the potential of PPy-coated fabrics for use as cardiovascular prostheses. It was suggested that cell adhesion moieties should be incorporated into the PPy/fabric composite to increase cell adhesion and subsequent cell proliferation.

Increasing referral of at-risk travelers to travel health clinics: evaluation of a health promotion intervention targeted to travel agents

BACKGROUND

Increases in travel-related illness require new partnerships to ensure travelers are prepared for health risks abroad. The travel agent is one such partner and efforts to encourage travel agents to refer at-risk travelers to travel health clinics may help in reducing travel-attributable morbidity.

METHODS

A health promotion intervention encouraging travel agents to refer at-risk travelers to travel health clinics was evaluated. Information on the knowledge, attitudes, and behaviors of travel agents before and after the intervention was compared using two self-administered questionnaires. The Wilcoxon signed rank test was used to compare the mean difference in overall scores to evaluate the overall impact of the intervention and also subscores for each of the behavioral construct groupings (attitudes, barriers, intent, and subjective norms). Multiple regression techniques were used to evaluate which travel agent characteristics were independently associated with a stronger effect of the intervention.

RESULTS

A small improvement in travel agents overall attitudes and beliefs (p =.03) was found, in particular their intention to refer (p =.01). Sixty-five percent of travel agents self-reported an increase in referral behavior; owners or managers of the agency were significantly more likely to do so than other travel agents (OR = 7.25; 95% CI: 1.64 32.06). Older travel agents, those that worked longer hours and those with some past referral experience, had significantly higher post-intervention scores.

CONCLUSIONS

Travel agents can be willing partners in referral, and agencies should be encouraged to develop specific referral policies. Future research may be directed toward investigating the role of health education in certification curricula, the effectiveness of different types of health promotion interventions, including Internet-facilitated interventions, and the direct impact that such interventions would have on travelers attending travel health clinics.

Diabetes in elderly adults

Diabetes is common in the elderly population. By the age of 75, approximately 20% of the population are afflicted with this illness. Diabetes in elderly adults is metabolically distinct from diabetes in younger patient populations, and the approach to therapy needs to be different in this age group. Diabetes is associated with substantial morbidity from macro- and microvascular complications. Several lines of evidence suggest that optimal glycemic control and risk factor modification can substantially reduce the risk of complications in elderly patients. In the past, treatment options were limited. However, recent studies have delineated several new and exciting therapeutic opportunities for elderly patients with diabetes.

Absence of perilipin results in leanness and reverses obesity in Lepr(db/db) mice

Obesity is a disorder of energy balance. Hormone-sensitive lipase (HSL) mediates the hydrolysis of triacylglycerol, the major form of stored energy in the body. Perilipin (encoded by the gene Plin), an adipocyte protein, has been postulated to modulate HSL activity. We show here that targeted disruption of Plin results in healthy mice that have constitutively activated fat-cell HSL. Plin -/- mice consume more food than control mice, but have normal body weight. They are much leaner and more muscular than controls, have 62% smaller white adipocytes, show elevated basal lipolysis that is resistant to beta-adrenergic agonist stimulation, and are cold-sensitive except when fed. They are also resistant to diet-induced obesity. Breeding the Plin -/- alleles into Leprdb/db mice reverses the obesity by ncreasing the metabolic rate of the mice. Our results demonstrate a role for perilipin in reining in basal HSL activity and regulating lipolysis and energy balance; thus, agents that inactivate perilipin may prove useful as anti-obesity medications.

Effects of aerobic physical exercise in the elderly with type 2 diabetes mellitus

The objective of this study was to determine the impact of an aerobic physical exercise program in the treatment of a group of elderly patients with type 2 diabetes mellitus (DM) in relation to metabolic control, physical capacity, quality of life (QOL) and attitudes toward diabetes. Patients were randomly assigned to either an experimental (n=19) or a control (n=20) group. The following measurements were conducted at baseline and after week 16: glycosylated hemoglobin (hbA1c), fructosamine, 3 h oral glucose tolerance test, treadmill test (Balke-Naughton), and a questionnaire on QOL and attitudes toward DM. After the intervention, the experimental group showed a significant decrease of glucose excursion during the oral glucose tolerance test (OGTT) (area under the curve) (16.6+/-3.8 vs. 15.3+/-3.1, P<0.05) and an increase in total time on the treadmill (s) (423+/-207 vs. 471+/-230, P<0.05). An improvement in the attitudes toward DM was observed in the experimental group (P=0.01) but not in the control group. Female gender, higher body mass index and hbA1c were factors associated with a response to the intervention. This study suggests that physical exercise has significant effects on glucose excursion during an OGTT and exercise tolerance in elderly patients with type 2 DM.

Effect of acarbose on insulin sensitivity in elderly patients with diabetes

OBJECTIVE

To study the effect of acarbose, an alpha-glucosidase inhibitor, on insulin release and insulin sensitivity in elderly patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Elderly patients with type 2 diabetes were randomly treated in a double-blind fashion with placebo (n = 23) or acarbose (n = 22) for 12 months. Before and after randomization, subjects underwent a meal tolerance test and a hyperglycemic glucose clamp study designed to measure insulin release and sensitivity.

RESULTS

After 12 months of therapy there was a significant difference in the change in fasting plasma glucose levels (0.2 +/- 0.3 vs. -0.5 +/- 0.2 mmol/l, placebo vs. acarbose group, respectively; P < 0.05) and in incremental postprandial glucose values (-0.4 +/- 0.6 vs. -3.5 +/- 0.6 mmol/l, placebo vs. acarbose group, P < 0.001) between groups. There was a significant difference in the change in HbA(1c) values in response to treatment (0.4 +/- 0.2 vs. -0.4 +/- 0.1%, placebo vs. acarbose group, P < 0.01). The change in fasting insulin in response to treatment (-2 +/- 2 vs. -13 +/- 4 pmol/l, placebo vs. acarbose group, P < 0.05) and incremental postprandial insulin responses (-89 +/- 26 vs. -271 +/- 59 pmol/l, placebo vs. acarbose group, P < 0.01) was also significantly different between groups. During the hyperglycemic clamps, glucose and insulin values were similar in both groups before and after therapy However, there was a significant difference in the change in insulin sensitivity in response to treatment between the placebo and the acarbose groups (0.001 +/- 0.001 vs. 0.004 +/- 0.001 mg/kg x min(-1) [pmol/l](-1), respectively, P < 0.05)

CONCLUSIONS

Acarbose increases insulin sensitivity but not insulin release in elderly patients with diabetes.

Evaluation of postural stability in elderly with diabetic neuropathy

OBJECTIVE

The objective of this study was to compare clinical and biomechanical characteristics of balance in diabetic polyneuropathic elderly patients and normal age-matched subjects.

RESEARCH DESIGN AND METHODS

Fifteen elderly with distal neuropathy (DNP) and 15 healthy age-matched subjects were evaluated with the biomechanical variable COP-COM, which represents the distance between the center of pressure (COP) and the center of mass (COM). Measurements were taken in the quiet position with a double-leg stance, in eyes-open (EO) and eyes-closed (EC) conditions. Subjects were also assessed with clinical balance evaluations.

RESULTS

The COP-COM variable was statistically significantly larger in the DNP group than in the healthy group in anterior-posterior (A/P) and medial-lateral (M/L) directions. Furthermore, the DNP group showed statistically significantly larger amplitudes of the COP-COM variable without vision. The severity of the neuropathy, as quantified using the Valk scoring system, was correlated with COP-COM amplitude in both directions.

CONCLUSIONS

Evaluation of the postural stability of an elderly diabetic population using the COP-COM variable can detect a very small change in postural stability and could be helpful in identifying elderly with DNP at risk of falling.

The degree of hyperinsulinemia and impaired glucose tolerance predicts plasma leptin concentrations in women only: a new exploratory paradigm

Plasma leptin has been shown to correlate positively with many indices of obesity, as well as insulin resistance. For a given body weight, the levels are higher in women than in men, but the reasons for this difference are not clear. Insulin has been shown to stimulate leptin production by adipose tissue in vivo and in vitro. Previous studies have reported that leptin levels are similar in diabetic and nondiabetic individuals. However, these studies were not performed in newly diagnosed diabetics, and other variables (such as gender) could have confounded the results. Therefore, the goal of the present cross-sectional study is to examine the effect of metabolic variables (such as glucose and insulin) on plasma leptin concentrations in men and women separately. We measured leptin levels in 48 subjects (17 with newly diagnosed type 2 diabetes mellitus, 13 with impaired glucose tolerance [IGT], and 18 normal individuals). The 3 groups were well matched for gender, age, and body mass index (BMI). When adjusted for the BMI and gender, a statistically significant gender-related difference in mean plasma leptin was observed across the 3 glucose tolerance subgroups (P < .03 by analysis of covariance [ANCOVA]). More specifically, plasma leptin levels were, on average, 44% lower in women with diabetes or IGT versus normal women (P < .02). No such between-group difference was observed in the men. In univariate analysis in the same female subgroup, plasma leptin correlated positively with fasting insulin (rs = +.43, P < .06) and negatively with 2-hour post-75-g glucose load plasma glucose concentration (rs = -.54, P < .02). In a multiple regression model controlling for the BMI in the female subgroup, circulating insulin and glucose concentrations 2 hours after the 75-g glucose load were good predictors of fasting plasma leptin (r = +.38, P = .02 and r = -.70, P < .001, respectively). Leptin levels in women appear to be influenced independently and to an important degree by ambient plasma glucose and plasma insulin concentrations. These findings suggest that the synthesis of leptin by adipose tissue is more susceptible to in vivo regulation by insulin and glucose in women than in men. Plasma leptin concentrations were also lower in women with IGT or type 2 diabetes versus normal women, suggesting that fasting and/or postprandial hyperglycemia interferes with the stimulatory effect of plasma insulin on the synthesis of leptin by adipose tissue in women only.

Polymerization and surface analysis of electrically-conductive polypyrrole on surface-activated polyester fabrics for biomedical applications

A new synthetic route is reported for the synthesis and covalent bonding of electrically conductive polypyrrole to a poly(ethylene terephthalate) fabric. It involves a three-step process including surface phosphorylation and graft polymerization from the gaseous phase. In the first step, the fibre surfaces are activated using phosphorus trichloride. Then, 1-(3-hydroxypropyl) pyrrole is introduced and grafted to the phosphorus chloride to create an ester bond between the fibres and the pyrrole. Finally, the pyrrole-grafted fibres are dipped in an aqueous FeCl3 catalyst and exposed to pyrrole monomer vapor for the final polymerization. This last step creates an electrically conductive polypyrrole layer covalently linked to the poly(ethylene terephthalate) fibres. ESCA analysis indicates a high degree of phosphorylation and grafting of the anchor molecules. Scanning electron microscopy reveals an overall smooth and uniform surface coating of polypyrrole on the polyester fibres. The use of ATR-FTIR spectroscopy is not able to distinguish between polypyrrole-coated and non-coated fabrics because of the extremely thin polypyrrole layer. Measurements of dynamic surface wetting indicated that the polypyrrole-coated fabric is more hydrophilic than the untreated control. With values for surface resistivity in the range 10(4)-10(5) ohmz/square, such polypyrrole-coated fabrics are considered attractive candidates for biomedical applications.

Effects of an oral glucose challenge on free radicals/antioxidants balance in an older population with type II diabetes

BACKGROUND

Our goal was to assess the effect of chronic vs acute hyperglycemia on free radicals (FR)/antioxidants balance in serum and leukocytes in an older (>65 years old) population with type II diabetes mellitus (DM).

METHODS

Case-control study comparing older male patients with type II DM with normal controls. FRs and antioxidants were measured at baseline and 120 min after an oral 100-g glucose load.

RESULTS

Baseline measurements showed an increased level of oxidized glutathione (GSSG) (p = .01) in the serum of diabetic subjects. Similar findings were observed at the intracellular level in the same group for GSSG (p = .0004), total glutathione (GSH + GSSG) (p = .0001) (GSH is reduced glutathione), decreased GSH/GSSG ratio (p = .0001), and ascorbic acid (p = .008). Monocytes from diabetic subjects produced larger amounts of nitric oxide (NO) in vitro (p = .03). After the oral glucose challenge, between-group comparisons demonstrated similar findings at the intracellular level for increased oxidized glutathione (p = .0004), GSH + GSSG (p = .0001), decreased GSH/GSSG (p = .0001), ascorbic acid (p = .02), and increased NO (p = .02) for the diabetic subjects. Within-group comparisons showed a significant drop of ascorbic acid in the control and the diabetic groups (p < .01), an increased level of GSSG in the diabetic group (p < .01), a decreased GSH/GSSG ratio (p < .05), and decreased production of NO by monocytes after in vitro stimulation in the control group (p < .05).

CONCLUSIONS

Our results suggest that type II diabetes in an older population is associated with increased basal oxidative stress. Hyperglycemic challenge is associated with an accentuation of this phenomenon as measured in the leukocytes.

Effects of gliclazide versus metformin on the clinical profile and lipid peroxidation markers in type 2 diabetes

The sulfonylurea gliclazide and the biguanide metformin have different mechanisms to reduce glycemia. We performed a randomized study to compare these two agents with respect to glycemic control and effects on lipid peroxidation markers in 36 adult patients with type 2 diabetes. Both agents significantly decreased glycosylated hemoglobin ([HbA1c] P < .05), fructosamine (P < .05), and the glucose-excursion curve during the oral glucose tolerance test ([OGTT] P < .01). With regard to the insulin curve during this test, no significant change was observed with metformin and a significant increase was measured with gliclazide (P < .05). Considering the small number of events, no significant difference was detected in the number of hypoglycemic episodes between the two agents. More upper-gastrointestinal (GI) symptoms were observed with metformin compared with gliclazide (P < .05). Even with no change in the standard lipid profile, both agents increased serum vitamin E (P < .01 for gliclazide and P < .05 for metformin) and decreased the level of lipid peroxidation markers in low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles (P < .05). Despite different mechanisms of action, gliclazide and metformin demonstrated comparable levels of efficacy and complementary effects on lipid peroxidation markers.

[First aid kits: for whom and why?]

Anyone traveling far from home should take along a first aid kit. Contents should be chosen carefully with the awareness that infection is not the main problem facing travelers. The basic kit is the same regardless of the purpose or duration of the trip or of the health and knowledge of the traveler. Priority should be given to allergic risks, to the quality of the thermometer, to the packaging of indispensable medications to a medical certificate justifying transport of drugs and syringes for personal medical use, and to preventive devices for sexually transmitted diseases. Travel in tropical zones raises special requirements especially with regard to infectious risks such as traveler's diarrhea, malaria, fungal and bacterial contamination. Protection against insect-borne disease and sun exposure are also important considerations for travel in the tropics. Depending on planned activities, travelers should carry medication for prevention and treatment of motion sickness and emergency treatment of envenimation. Due to local inavailabilities, it may be necessary to pack contraceptives, personal hygiene products, and common medications.

[How to plan travel vaccinations when they are numerous or the traveler is pressed for time?]

Deciding on the best immunizations and their best sequence of administration for some travellers may be wavering. Numerous resources documents and tools are available to help the travel medicine expert in his or her decision making process. Still, many factors are to be considered and weighed. These include time, money, uncertain itinerary, health status, fears and beliefs of the traveller and the number of available injection sites. The specific needs of the traveller should be assessed with minutia. The evaluation will look at the type of accommodation planed, the purpose of the travel, the distance covered, the mode of transportation, and previous travel experience. Inevitably, some travellers will leave the country without receiving all recommended immunizations. They should be part of the decision process when some are to be sacrificed. Information is essential for an enlightened choice, and it is the responsibility of the travel medicine expert to provide it.

NIDDM in the elderly

OBJECTIVE

We conducted this study to assess the metabolic alterations in elderly patients with NIDDM.

RESEARCH DESIGN AND METHODS

Healthy, lean (n = 15; age, 73 +/- 1 years; BMI, 23.8 +/- 0.5 kg/m2), and obese (n = 10; age, 71 +/- 1 years; BMI, 28.9 +/- 1.2 kg/m2) control subjects and lean (n = 10; age, 75 +/- 2 years; BMI, 24.0 +/- 0.5 kg/m2) and obese (n = 23; age, 73 +/- 1 years; BMI, 29.9 +/- 0.7 kg/m2) NIDDM patients underwent a 3-h glucose tolerance test, a 2-h hyperglycemic glucose clamp study, and a 3-h euglycemic glucose clamp study with tritiated glucose methodology to measure glucose production and disposal rates.

RESULTS

Waist-to-hip ratio (WHR) was greater in both lean and obese NIDDM patients than in control subjects. Insulin responses during the oral glucose tolerance test were similar in obese subjects (control subjects: 417 +/- 64 pmol/l; NIDDM patients: 392 +/- 47 pmol/l) but were reduced in lean NIDDM patients (control subjects: 374 +/- 34 pmol/l; NIDDM patients: 217 +/- 20 pmol/l, P < 0.01). Lean and obese NIDDM patients had absent first-phase insulin responses during the hyperglycemic clamp. Second-phase insulin responses were reduced in lean (P < 0.01 vs. control subjects by analysis of variance) but not obese NIDDM patients. Hepatic glucose output was not increased in lean or obese NIDDM patients. Steady-state (150-180 min) glucose disposal rates were 16% less in lean NIDDM patients (control subjects: 8.93 +/- 0.37 mg.kg LBM (lean body mass)-1.min-1; NIDDM patients: 7.50 +/- 0.28 mg.kg LBM-1.min-1, P < 0.05) and 37% less in obese NIDDM patients (control subjects: 8.17 +/- 0.38 mg.kg LBM-1.min-1; NIDDM patients: 5.03 +/- 0.36 mg.kg LBM-1.min-1, P < 0.001).

CONCLUSIONS

Lean elderly NIDDM patients have a profound impairment in glucose-induced insulin release but mild resistance to insulin-mediated glucose disposal. Obese elderly NIDDM patients have adequate circulating insulin, but marked resistance to insulin-mediated glucose disposal. Hepatic glucose output is not increased in elderly NIDDM patients.

Crystallization of a soluble form of the Kex1p serine carboxypeptidase from Saccharomyces cerevisiae

A soluble form of the killer factor and prohormone-processing carboxypeptidase, "Kex1 delta p," from Saccharomyces cerevisiae, has been crystallized in 17-22% poly(enthylene glycol) methyl ether (average M(r) = 5,000), 100 mM ammonium acetate, 5% glycerol, pH 6.5, at 20 degrees C. A native data set (2.8 A resolution) and four derivative data sets (3.0-3.2 A resolution) were collected at the Photon Factory (lambda = 1.0 A). The crystals belong to space group P2(1)2(1)2(1) with a =56.6 A, b = 84.0 A, c = 111.8 A. Freezing a Kex1 delta p crystal has facilitated the collection of a 2.4-A data set using a rotating anode source (lambda = 1.5418 A). Molecular replacement models have been built based on the structures of wheat serine carboxypeptidase (CPDW-II; Liao DI et al., 1992, Biochemistry 31:9796-9812) and yeast carboxypeptidase Y.

Diabetes in the elderly

Diabetes affects at least 20% of the population over the age of 65. Half of these patients are unaware that they have the disease. Diabetes in middle-aged subjects is characterized by an impairment in glucose induced insulin release, increased fasting hepatic glucose output and resistance to insulin mediated glucose disposal. In contrast, diabetes in the elderly is primarily associated with insulin deficiency. The presentation of diabetes in the aged is often non-specific. The elderly have an increased frequency of complications from diabetes. They are particularly susceptible to hypoglycaemia, because of reduced awareness of hypoglycaemic warning symptoms and altered release of counterregulatory hormones. Although no data are yet available from randomized controlled trials, there is abundant epidemiological evidence to suggest that adequate control of blood glucose can be expected to reduce the risk of long-term complications. A team approach is ideal for the management of the elderly patient with diabetes. Little data is available on which to base a diet and exercise prescription for elderly patients. Gliclazide appears to be the sulphonylurea of choice in the aged because it is associated with a lower frequency of hypoglycaemic reactions. Urine glucose testing is unreliable, and capillary glucose monitoring is preferred. Fructosamine may prove to be superior to haemoglobin A1C for monitoring long-term control.

Electrochemical and microstructural study of oxide films formed electrochemically at microcrystalline Al-Fe-V-Si alloys

A recent advance in metallurgical technology has been the application of rapid solidification techniques to Al alloy production. FVS0812 is the designation given to a microcrystalline Al-based alloy consisting of 8 wt% Fe, 1 wt% V and 2 wt% Si. It is a two-phase alloy, consisting of ca. 27 vol percent of approximately spherical Fe-V-Si-rich dispersoids in an essentially pure Al matrix. The high strength, low density properties of this advanced material, and other related alloys, have not yet been realized, however, due, in part, to the inability of the alloy to form a thick, adherent, abrasion-resistant outer surface oxide film, a feature readily achieved at conventional Al alloys by normal anodizing methods. The present research has involved an electro-chemical study of oxide film growth at the 812 alloy, with the specific goals being to seek an understanding of the origin of the oxide film growth problem and ultimately to propose alternative approaches to the formation of a thick, stable oxide film at this material. The techniques used in this research have included electrochemical methodologies such as cyclic voltammetry and electrochemical impedance spectroscopy. Crucial information has been obtained through transmission electron microscopy (TEM) of ultramicrotomed specimens. Experiments were carried out initially in neutral borate solutions to characterize the compact barrier oxide film formed in this environment and expected to be present beneath the porous oxide film formed in the normal sulfuric acid anodizing medium.(ABSTRACT TRUNCATED AT 250 WORDS)