Deletion of vascular thromboxane A2 receptors and its impact on angiotensin II-induced hypertension and atherosclerotic lesion formation in the aorta of Ldlr-deficient mice

The thromboxane A2 receptor (TP) has been shown to play a role in angiotensin II (Ang II)-mediated hypertension and pathological vascular remodeling. To assess the impact of vascular TP on Ang II-induced hypertension, atherogenesis, and pathological aortic alterations, i.e. aneurysms, we analysed Western-type diet-fed and Ang II-infused TPVSMC KO/Ldlr KO, TPEC KO/Ldlr KO mice and their respective wild-type littermates (TPWT/Ldlr KO). These analyses showed that neither EC- nor VSMC-specific deletion of the TP significantly affected basal or Ang II-induced blood pressure or aortic atherosclerotic lesion area. In contrast, VSMC-specific TP deletion abolished and EC-specific TP deletion surprisingly reduced the ex vivo reactivity of aortic rings to the TP agonist U-46619, whereas VSMC-specific TP knockout also diminished the ex vivo response of aortic rings to Ang II. Furthermore, despite similar systemic blood pressure, there was a trend towards less atherogenesis in the aortic arch and a trend towards fewer pathological aortic alterations in Ang II-treated female TPVSMC KO/Ldlr KO mice. Survival was impaired in male mice after Ang II infusion and tended to be higher in TPVSMC KO/Ldlr KO mice than in TPWT/Ldlr KO littermates. Thus, our data may suggest a deleterious role of the TP expressed in VSMC in the pathogenesis of Ang II-induced aortic atherosclerosis in female mice, and a surprising role of the endothelial TP in TP-mediated aortic contraction. However, future studies are needed to substantiate and further elucidate the role of the vascular TP in the pathogenesis of Ang II-induced hypertension, aortic atherosclerosis and aneurysm formation.

The F2-isoprostane 8-iso-PGF2α attenuates atherosclerotic lesion formation in Ldlr-deficient mice - Potential role of vascular thromboxane A2 receptors

The F2-isoprostane 8-iso-PGF_2α (also known as 15-F_2t-isoprostane, iPF_2α-III, 8-epi PGF_2α, 15(S)-8-iso-PGF_2α, or 8-Isoprostane), a thromboxane A₂ receptor (TP) agonist, stable biomarker of oxidative stress, and risk marker of cardiovascular disease, has been proposed to aggravate atherogenesis in genetic mouse models of atherosclerotic vascular disease. Moreover, the TP plays an eminent role in the pathophysiology of endothelial dysfunction, atherogenesis, and cardiovascular disease. Yet it is unknown, how the TP expressed by vascular cells affects atherogenesis or 8-iso-PGF_2α-related effects in mouse models of atherosclerosis. We studied Ldlr-deficient vascular endothelial-specific (EC) and vascular smooth muscle cell (VSMC)-specific TP knockout mice (TP^ECKO/Ldlr KO; TP^VSMCKO/Ldlr KO) and corresponding wild-type littermates (TP^WT/Ldlr KO). The mice were fed a Western-type diet for eight weeks and received either 8-iso-PGF_2α or vehicle infusions via osmotic pumps. Subsequently, arterial blood pressure, atherosclerotic lesion formation, and lipid profiles were analyzed. We found that VSMC-, but not EC-specific TP deletion, attenuated atherogenesis without affecting blood pressure or plasma lipid profiles of the mice. In contrast to a previous report, 8-iso-PGF_2α tended to reduce atherogenesis in TP^WT/Ldlr KO and TP^{EC KO}/Ldlr KO mice, again without significantly affecting blood pressure or lipid profiles of these mice. However, no further reduction in atherogenesis was observed in 8-iso-PGF_2α-treated TP^{VSMC KO}/Ldlr KO mice. Our work suggests that the TP expressed in VSMC but not the TP expressed in EC is involved in atherosclerotic lesion formation in Ldlr-deficient mice. Furthermore, we report an inhibitory effect of 8-iso-PGF_2α on atherogenesis in this experimental atherosclerosis model, which paradoxically appears to be related to the presence of the TP in VSMC.

A Thromboxane A2 Receptor-Driven COX-2-Dependent Feedback Loop That Affects Endothelial Homeostasis and Angiogenesis

BACKGROUND

TP (thromboxane A₂ receptor) plays an eminent role in the pathophysiology of endothelial dysfunction and cardiovascular disease. Moreover, its expression is reported to increase in the intimal layer of blood vessels of cardiovascular high-risk individuals. Yet it is unknown, whether TP upregulation per se has the potential to affect the homeostasis of the vascular endothelium.

METHODS

We combined global transcriptome analysis, lipid mediator profiling, functional cell analyses, and in vivo angiogenesis assays to study the effects of endothelial TP overexpression or knockdown/knockout on the angiogenic capacity of endothelial cells in vitro and in vivo.

RESULTS

Here we report that endothelial TP expression induces COX-2 (cyclooxygenase-2) in a G_i/o- and G_q/11-dependent manner, thereby promoting its own activation via the auto/paracrine release of TP agonists, such as PGH₂ (prostaglandin H₂) or prostaglandin F₂ but not TxA₂ (thromboxane A₂). TP overexpression induces endothelial cell tension and aberrant cell morphology, affects focal adhesion dynamics, and inhibits the angiogenic capacity of human endothelial cells in vitro and in vivo, whereas TP knockdown or endothelial-specific TP knockout exerts opposing effects. Consequently, this TP-dependent feedback loop is disrupted by pharmacological TP or COX-2 inhibition and by genetic reconstitution of PGH₂-metabolizing prostacyclin synthase even in the absence of functional prostacyclin receptor expression.

CONCLUSIONS

Our work uncovers a TP-driven COX-2-dependent feedback loop and important effector mechanisms that directly link TP upregulation to angiostatic TP signaling in endothelial cells. By these previously unrecognized mechanisms, pathological endothelial upregulation of the TP could directly foster endothelial dysfunction, microvascular rarefaction, and systemic hypertension even in the absence of exogenous sources of TP agonists.

Enduring Effects of Conditional Brain Serotonin Knockdown, Followed by Recovery, on Adult Rat Neurogenesis and Behavior

Serotonin (5-hydroxytryptamine, 5-HT) is a crucial signal in the neurogenic niche of the hippocampus, where it is involved in antidepressant action. Here, we utilized a new transgenic rat model (TetO-shTPH2), where brain 5-HT levels can be acutely altered based on doxycycline (Dox)-inducible shRNA-expression. On/off stimulations of 5-HT concentrations might uniquely mirror the clinical course of major depression (e.g., relapse after discontinuation of antidepressants) in humans. Specifically, we measured 5-HT levels, and 5-HT metabolite 5-HIAA, in various brain areas following acute tryptophan hydroxylase 2 (Tph2) knockdown, and replenishment, and examined behavior and proliferation and survival of newly generated cells in the dentate gyrus. We found that decreased 5-HT levels in the prefrontal cortex and raphe nuclei, but not in the hippocampus of TetO-shTPH2 rats, lead to an enduring anxious phenotype. Surprisingly, the reduction in 5-HT synthesis is associated with increased numbers of BrdU-labeled cells in the dentate gyrus. At 3 weeks of Tph2 replenishment, 5-HT levels return to baseline and survival of newly generated cells is unaffected. We speculate that the acutely induced decrease in 5-HT concentrations and increased neurogenesis might represent a compensatory mechanism.

Alterations in BDNF Protein Concentrations in the Hippocampus do not Explain the Pro-Neurogenic Effect of Citalopram on Adult Neurogenesis

INTRODUCTION

Brain-derived neurotrophic factor (BDNF) has been implicated in the pro-neurogenic effect of selective serotonin reuptake inhibitors. In this study, we used Tph2 ^-/- mice lacking brain serotonin to dissect the interplay between BDNF and the serotonin system in mediating the effects of antidepressant pharmacotherapy on adult neurogenesis in the hippocampus.

METHODS

Besides citalopram (CIT), we tested tianeptine (TIA), an antidepressant whose mechanism of action is not well understood. Specifically, we examined cell survival and endogenous concentrations of BDNF following daily injection of the drugs.

RESULTS

Twenty-one days of CIT, but not of TIA, led to a significant increase in the survival of newly generated cells in the dentate gyrus of wild-type mice, without a significant effect on BDNF protein levels by either treatment. In Tph2 ^-/- mice, adult neurogenesis was consistently increased. Furthermore, Tph2 ^-/- mice showed increased BDNF protein levels, which were not affected by TIA but were significantly reduced by CIT.

DISCUSSION

We conclude that the effects of CIT on adult neurogenesis are not explained by changes in BDNF protein concentrations in the hippocampus.

Brain serotonin critically contributes to the biological effects of electroconvulsive seizures

Compounds targeting serotonin (5-HT) are widely used as antidepressants. However, the role of 5-HT in mediating the effects of electroconvulsive seizure (ECS) therapy remains undefined. Using Tph2^-/- mice depleted of brain 5-HT, we studied the effects of ECS on behavior and neurobiology. ECS significantly prolonged the start latency in the elevated O-Maze test, an effect that was abolished in Tph2^-/- mice. Furthermore, in the absence of 5-HT, the ECS-induced increase in adult neurogenesis and in brain-derived neurotrophic factor signaling in the hippocampus were significantly reduced. Our results indicate that brain 5-HT critically contributes to the neurobiological responses to ECS.

Ultra low noise Fourier domain mode locked laser for high quality megahertz optical coherence tomography

We investigate the origin of high frequency noise in Fourier domain mode locked (FDML) lasers and present an extremely well dispersion compensated setup which virtually eliminates intensity noise and dramatically improves coherence properties. We show optical coherence tomography (OCT) imaging at 3.2 MHz A-scan rate and demonstrate the positive impact of the described improvements on the image quality. Especially in highly scattering samples, at specular reflections and for strong signals at large depth, the noise in optical coherence tomography images is significantly reduced. We also describe a simple model that suggests a passive physical stabilizing mechanism that leads to an automatic compensation of remaining cavity dispersion in FDML lasers.

Enhancement of gravimetric forced flow through system to determine sorption, swelling, and mass transfer characteristics of liquid sorbents

An existing apparatus for forced flow through of liquid sorbents has been enhanced with an optically accessible system including a transparent crucible, high pressure viewing cell, and camera. With this optical system, the active surface area between gas and liquid can be determined in situ for the first time under industrial process conditions while maintaining the accuracy of a magnetic suspension balance. Additionally, occurring swelling and the resulting buoyancy changes can now be corrected, further improving the quality of the data. Validation measurements focusing on the sorption isotherms, swelling, and bubble geometry of 1-butyl-3-methylimidazolium tetrafluoroborate with nitrogen at 303 K and up to 17 MPa, as well as with carbon dioxide at 303 K, 323 K, and 373 K at up to 3.5 MPa were completed. Absorption of nitrogen resulted in no observable volume change, whereas absorption of carbon dioxide resulted in temperature independent swelling of up to 9.8%. The gas bubble's structure and behavior during its ascend through the liquid was optically tracked in situ. Combining these two data sets with the absorption kinetics forms the basis to determine the measuring system independent mass transfer coefficients, which are applicable in other laboratory scale and industrial processes.

Simultaneous measurement of surface tension and viscosity using freely decaying oscillations of acoustically levitated droplets

Oscillations of small liquid drops around a spherical shape have been of great interest to scientists measuring physical properties such as interfacial tension and viscosity, over the last few decades. A powerful tool for contactless positioning is acoustic levitation, which has been used to simultaneously determine the surface tension and viscosity of liquids at ambient pressure. In order to extend this acoustic levitation measurement method to high pressure systems, the method is first evaluated under ambient pressure. To measure surface tension and viscosity using acoustically levitated oscillating drops, an image analysis method has to be developed and factors which may affect measurement, such as sound field or oscillation amplitude, have to be analyzed. In this paper, we describe the simultaneous measurement of surface tension and viscosity using freely decaying shape oscillations of acoustically levitated droplets of different liquids (silicone oils AK 5 and AK 10, squalane, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol) in air. These liquids vary in viscosity from 2 to about 30 mPa s. An acoustic levitation system, including an optimized standing wave acoustic levitator and a high-speed camera, was used for this study. An image analysis was performed with a self-written Matlab® code. The frequency of oscillation and the damping constant, required for the determination of surface tension and viscosity, respectively, were calculated from the evolution of the equatorial and polar radii. The results and observations are compared to data from the literature in order to analyze the accuracy of surface tension and viscosity determination, as well as the effect of non-spherical drop shape or amplitude of oscillation on measurement.

[The impact of capsular repair on the dislocation rate after primary total hip arthroplasty: a retrospective analysis of 1972 cases]

BACKGROUND

Dislocation is the second most frequently encountered complication in primary total hip arthroplasty (THA) and occurs more commonly in the early postoperative rehabilitation phase. Sir Charnley recommended the "avoidance of resection of the capsule" and emphasised its contribution to hip joint stability in THA. Several authors, however, doubted its significance and considered resection of the capsule to be essential. Since 2002, some surgeons increasingly adopted a modified, less invasive technique of THA via Bauer approach, including the preservation and repair of the hip joint capsule with focus on maintaining its acetabular origin. Another group of surgeons applied the traditional technique including the resection of the joint capsule via an anterolateral approach. In this case-control study we investigated whether the dislocation rate can be reduced through joint capsule reconstruction and whether any negative impact on patient satisfaction, functional results or revision rate is observed.

MATERIAL AND METHODS

All cases of primary THA performed in our institution in a timeframe between 2002 and 2009 were included with the only exceptions of resurfacing arthroplasty, dual mobility and tumour hip replacements. Joint capsule repair cases were gathered in the study group (SG), capsule resection cases in the control group (CG). Additional patient-related data were taken from the anaesthesia records. The WOMAC score and a questionnaire focusing on detection of dislocations and revision surgeries was sent out for each case. Further targeted research was conducted that included requesting records and reports from external hospitals. In the case of non-responding patients, all available data (operating room documentation, electronic files, archive, X-rays) were reviewed for incidents of dislocation and revision surgery. Groupings and classifications were exclusively performed by senior surgeons. SG and CG were compared regarding epidemiologic, implant-associated and surgery-specific data. Statistical evaluations were performed using the Chi-squared test and the Mann-Whitney U test.

RESULTS

1972 cases of primary THA were included: 992 in the SG and 980 in the CG. The follow-up rates were 92.7 % in the SG and 76.4 % in the CG, the mean follow-up times 33.5 months and 73.4 months, respectively, with a follow-up of at least 12 months in all cases. In the SG, the dislocation rate was 0.3 % (n = 3) and thus significantly lower than the 2.55 % in the CG (n = 25, p < 0.001). Both the WOMAC score (SG: 1.46 ± 1.73; CG: 1.53 ± 1.80; p > 0.05) and the revision rate (SG: 5.24 %; CG: 6.84 %; p = 0.139) showed no significant differences.

CONCLUSION

Preservation and repair of the hip joint capsule causes an 88-%-reduction of the dislocation rate in primary THA in this large series including 1972 cases, operated via the Bauer or the anterolateral approach. Several authors reported comparable results after THA using similar techniques of soft tissue and capsular repair through the posterior or posterolateral approach. Sparing and reconstructing the hip joint capsule therefore seems to reduce the dislocation rate after primary THA by one order of magnitude regardless of the surgical approach and, especially, if the acetabular origin is preserved. Capsule-related specific complications such as an increased revision rate, malfunction or pain were neither recorded in our study nor by others. Thus, careful preservation and reconstruction of the hip joint capsule may be expressly recommended in primary THA.

Lean and fat mass as determinants of muscle strength and insulin sensitivity in Chilean elderly subjects

PURPOSE

To report the association of lean body mass with nutritional, social and economic factors and its functional consequences in free living healthy elderly subjects.

MATERIAL AND METHODS

Healthy elderly subjects of low socioeconomic level were studied. Monthly income, marital status, anthropometric measures and fall risk were assessed. Mini Nutritional Assessment score was calculated. Body composition and bone mineral density were measured by double beam X ray absorptiomentry. Fasting serum lipids, fasting and postprandial insulin and glucose levels were measured. Hand grip, quadriceps and biceps strengths and maximal inspiratory and expiratory pressures were measured.

RESULTS

One hundred and nine subjects (56 women), aged 75 +/- 4 years old were studied. Lean body mass was 34.1 +/- 4 and 49.2 +/- 5.4 kg in women and men respectively (p < 0.001), fat mass was 22.8 +/- 7.1 and 20.7 +/- 6.4 kg in women and men respectively (p= NS). Lean body mass correlated with hand grip, quadriceps and biceps muscle strengths in men and with quadriceps and biceps strength in women. Men that exercised regularly had higher quadriceps strength and maximal expiratory pressure. Total body fat correlated positively with fasting and postprandial serum insulin levels.

CONCLUSIONS

In this sample, lean body mass is directly related to muscle strength mostly in men. On the other hand, total fat mass is related to serum insulin levels.

Effects of nutritional supplementation and resistance training on muscle strength in free living elders. Results of one year follow

PURPOSE

To assess the effects of a one year nutritional supplementation and resistance training program on muscle strength and walking capacity in the elderly.

MATERIAL AND METHODS

Elderly subjects from two outpatient clinics received a nutritional supplement, that provided 400 Kcal, 15 g/protein and 50% of vitamin DRVs per day. Half the subjects receiving and not receiving the supplement were randomly assigned to a resistance exercise training program with two sessions per week. Every six months, body composition using DEXA, limb muscle strength, maximal inspiratory and expiratory pressures and walking capacity were assessed.

RESULTS

One hundred forty nine subjects were considered eligible and 101 (31 supplemented and trained, 28 supplemented, 16 trained and 26 without supplementation nor training) completed the year of follow up. Overall compliance with the supplement was 48 22 % and trained subjects attended 56 21% of programmed sessions. No changes in fat free mass were observed in any of the groups, but fat mass increased from 22.5 7.3 to 23.2 7.3 kg in all groups (p < 0.001). Upper and lower limb strength and walking capacity increased significantly in trained subjects whether supplemented or not. Maximal inspiratory pressure and right hand grip strength increased only in the supplemented and trained group.

CONCLUSIONS

Resistance training improved muscle strength and walking capacity.

The impact of nutritional supplementation and resistance training on the health functioning of free-living Chilean elders: results of 18 months of follow-up

Body composition changes and loss of functionality in the elderly are related to substandard diets and progressive sedentariness. The aim of this study was to assess the impact of an 18-mo nutritional supplementation and resistance training program on health functioning of elders. Healthy elders aged > or = 70 y were studied. Half of the subjects received a nutritional supplement. Half of the supplemented and nonsupplemented subjects were randomly assigned to a resistance exercise training program. Every 6 mo, a full assessment was performed. A total of 149 subjects were considered eligible for the study and 98 (31 supplemented and trained, 26 supplemented, 16 trained and 25 without supplementation or training) completed 18 mo of follow-up. Compliance with the supplement was 48%, and trained subjects attended 56% of programmed sessions. Activities of daily living remained constant in the supplemented subjects and decreased in the other groups. Body weight and fat-free mass did not change. Fat mass increased from 22.2 +/- 7.6 to 24.1 +/- 7.7 kg in all groups. Bone mineral density decreased less in both supplemented groups than in the nonsupplemented groups (ANOVA, P < 0.01). Serum cholesterol remained constant in both supplemented groups and in the trained groups, but it increased in the control group (ANOVA, P < 0.05). Upper and lower limb strength, walking capacity and maximal inspiratory pressure increased in trained subjects. In conclusion, patients who were receiving nutritional supplementation and resistance training maintained functionality, bone mineral density and serum cholesterol levels and improved their muscle strength.

Low serum folate but normal homocysteine levels in patients with atherosclerotic vascular disease and matched healthy controls

Mild hyperhomocysteinemia has been considered a cardiovascular risk factor. However, recent prospective studies have not demonstrated that hyperhomocysteinemia or the underlying genetic defect on methylentetrahydrofolate reductase is associated with a higher risk of coronary or peripheral artery disease. We compared serum homocysteine, folate, and vitamin B(12) levels of patients with coronary and peripheral vascular disease with those of age- and sex-matched healthy individuals. Subjects taking multivitamins, with diabetes mellitus, or serum creatinine levels over 1.5 mg/dL were excluded from the study. Homocysteine was measured by fluorimetric high-performance liquid chromatography. Serum folate and vitamin B(12) levels were measured by an ion-capture method. We studied 32 patients with peripheral vascular disease (10 female), aged 69.6 +/- 11 y, 24 age- and sex-matched control subjects, 52 patients with coronary artery disease (7 female), aged 59.5 +/- 10.4 y, and 42 age- and sex-matched control subjects. Serum homocysteine levels were 11.7 +/- 7.4 and 9.3 +/- 4.5 micromol/L in vascular patients and in the control counterparts, respectively (not significant). The levels for coronary patients and the control counterparts were 9.0 +/- 3.9 and 8.6 +/- 3.6 micromol/L, respectively (not significant). Folate levels were 4.48 +/- 2.42 and 7.14 +/- 4.04 ng/mL in vascular patients and control subjects, respectively (P < 0.02); the levels in coronary patients and control counterparts were 5.15 +/- 1.9 and 6.59 +/- 2.49 ng/mL, respectively (P < 0.01). No differences in vitamin B(12) or tocopherol levels were observed between patients and control subjects. There were no differences in homocysteine levels, but lower serum folate levels were observed when comparing patients with atherosclerotic vascular disease and healthy control subjects.

Changes in microsomal activity in alcoholism and obesity

BACKGROUND

Liver damage is more prevalent among obese alcoholics, and cytochrome P-4502E1(CYP2E1) induction is involved in its pathogenesis.

OBJECTIVES

The study was undertaken to assess microsomal function, in alcoholic and nonalcoholic male subjects with different body compositions, through pharmacokinetics of chlorzoxazone (CLZ). We also intended to study the relationship between CLZ hydroxylation and urinary levels of 8-hydroxydiguanosine, and between CLZ levels and liver histology.

METHODS

Serial measurements of CLZ serum concentration, after a 750 mg dose, were performed in 17 alcoholics (9 normal weight and 8 obese) and 21 nonalcoholic subjects (10 normal weight and 11 obese). Concentration of 6-hydroxy-chlorzoxazone (6-OH-CLZ) was determined at the second hour. Anthropometry, clinical laboratory tests, and urinary 8-hydroxydiguanosine concentrations were measured. Liver biopsies were performed in alcoholics.

RESULTS

Five biopsies revealed severe lesions, one in normal-weight and four in obese patients (p = NS). Area under the curve (AUC) of CLZ was higher in normal-weight controls compared with the rest of the groups (ANOVA p = 0.001). This parameter correlated negatively with adiposity in nonalcoholic subjects and did not correlate with liver histology. 6-OH-CLZ/CLZ ratio was lower in normal-weight controls, compared with obese subjects and normal-weight alcoholics (p = 0.02). Both alcoholism and obesity were included as predictors of CLZ AUC in a multiple regression analysis. The two-factor ANOVA showed an additive effect of centripetal body fat distribution and alcoholism. Urinary 8-hydroxydiguanosine levels were extremely variable.

CONCLUSIONS

Centripetal adiposity and alcoholism are associated with induction of CYP2E1. This may explain the higher prevalence of liver damage among obese alcoholics and also nonalcoholic steatohepatitis.

Effects of supplementation with folic acid and antioxidant vitamins on homocysteine levels and LDL oxidation in coronary patients

Hyperhomocysteinemia is an important cardiovascular risk factor. Serum homocysteine levels are specially dependent on folate nutritional status. In addition, the oxidative modification of low-density lipoproteins (LDLs) in the endothelial microenvironment is a damaging factor that can be modified with fat-soluble antioxidant vitamins. The present study was done to assess the effect of a supplementation of folic acid and antioxidant vitamins on homocysteine levels and in vitro LDL oxidation in patients with coronary artery disease. Twenty-three patients with angiographically proven coronary artery disease were given supplements for 15 d consisting of one capsule twice a day of a multivitamin preparation containing 0.65 mg folic acid, 150 mg alpha-tocopherol, 150 mg ascorbic acid, 12.5 mg beta-carotene, and 0.4 microgram vitamin B12. Serum lipids, vitamin and homocysteine levels, and in vitro LDL oxidation were measured before and after the supplementation period. During the supplementation period, serum folate levels increased from 5.0 +/- 1.5 to 10.8 +/- 3.8 ng/mL (P < 0.001), vitamin B12 increased from 317.4 +/- 130.4 to 334.5 +/- 123.8 pg/mL (P < 0.05), and alpha-tocopherol increased from 8.2 +/- 5.1 to 13.7 +/- 7.9 mg/L (P < 0.001). Serum homocysteine levels decreased from 8.7 +/- 4.3 to 6.3 +/- 2.2 mumol/L (P < 0.001). In vitro LDL oxidation decreased from 2.6 +/- 1.1 to 1.6 +/- 1.1 nmol malondialdehyde/mg protein (P < 0.001). In comparing patients with healthy controls, basal levels of folate were lower in the patients, whereas vitamin B12, alpha-tocopherol, and homocysteine levels were similar. No changes in serum lipid levels or body weight were observed. In conclusion, a short-term supplementation with folic acid and antioxidant vitamins can reduce serum homocysteine levels and in vitro LDL oxidation in patients with coronary artery disease.

Nutritional support in alcoholic cirrhotic patients improves host defenses

BACKGROUND

Malnutrition is usual in patients with alcoholic liver disease and is associated with a poor outcome. Nutritional support decreases nutrition-associated complications.

AIM

To demonstrate that nutritional support in ambulatory alcoholic cirrhotic patients improves host defenses.

METHODS

Thirty-one male outpatients with alcoholic cirrhosis CHILD-PUGH B or C were included. Twenty-five subjects completed six months consuming daily a nutritional supplement (Ensure, 1000 Kcal and 35 g protein), in addition to their regular diet. At entrance and every three months, a clinical assessment, nutritional evaluation and indirect calorimetry were performed. Liver function tests and LPS-induced monocyte production of cytokines, salivary secretory IgA, lactulose/mannitol ratio and breath hydrogen tests were also measured in these intervals. Delayed cutaneous hypersensitivity and IgG and IgM antibody response to endotoxin were assessed at entrance and at the end of the study.

RESULTS

Patients drank 85% of the provided supplement as an average. REE, total body fat and serum albumin increased, basal breath hydrogen decreased and cellular immunity improved significantly during the follow up period (p< or =0.03). All the other parameters remained unchanged throughout the study. Six patients (16.2%) died during the study, five due to upper gastrointestinal bleeding.

CONCLUSION

Nutritional support in alcoholic cirrhotic patients improves nutritional status and cell mediated immunity.

[Serum homocysteine levels in healthy Chilean adults]

BACKGROUND

Hyperhomocysteinemia is a newly recognized cardiovascular risk factor that is present in 10 to 20% of European and North American individuals.

AIM

To measure homocysteine levels in healthy adults in Chile.

SUBJECTS AND METHODS

Serum homocysteine levels were measured in healthy adults using a fluorimetric HPLC method. Folic acid, vitamin. B12, serum lipids, creatinine and glucose were also assessed. All subjects answered a dietary habits questionnaire.

RESULTS

One hundred twenty eight subjects (90 female) aged 22 to 78 years old were studied. Homocysteine levels were 9.7 +/- 6.0 and 7.0 +/- 3.1 mumol/l in men and women respectively (p < 0.001). Folic acid levels were 6.1 +/- 2.7 and 6.1 +/- 2.9 ng/ml in men and women, and 24% of individuals had values below 4 ng/ml. Vitamin B12 levels were 393 +/- 147 and 393 +/- 163 pg/ml in the same groups. There was a negative correlation between homocysteine and folic acid levels and a positive correlation between homocysteine and creatinine levels.

CONCLUSIONS

Homocysteine levels in healthy Chilean individuals are similar to those reported abroad. Low folic acid levels were found in 24% of subjects.

Lipid turnover in alcoholics before and after an ethanol load

Alcohol ingestion decreases plasma free fatty acids (FFAs) and lipid oxidation. This study was conducted to determine palmitate turnover in alcoholics during a short abstinence period and after an ethanol load and in a group of nonalcoholic control subjects, looking for correlations between palmitate turnover, FFA, acetate, and acetoacetate/beta hydroxybutyrate ratio (AKBR). Palmitate C14 turnover was studied in five alcoholics during early abstinence and after a 0.8 g/kg ethanol load, and in five nonalcoholic normal controls. Plasma levels of FFA, acetate, acetoacetate, and beta hydroxybutyrate were measured before and during the ethanol load. A needle hepatic biopsy was performed in alcoholics. FFA levels, palmitate flux, oxidation, and nonoxidative disposal were similar in alcoholics compared with control subjects, decreasing significantly after the ethanol load in both groups. AKBR and ketone bodies were similar in both groups in the basal period. After the alcohol infusion, AKBR decreased significantly. Acetoacetate levels did not change, and beta hydroxybutyrate and total ketone bodies increased significantly in alcoholics and control subjects. A positive correlation was found between FFA levels and palmitate flux. Liver biopsies showed mild changes in the patients studied. The similar inhibition of lipid turnover, FFA release, and the drop in AKBR observed after an alcohol load in alcoholics and control subjects suggest that this effect is mediated by alcohol metabolism and not by metabolic alterations present in alcoholics.

Administration of medications through enteral feeding catheters

BACKGROUND: Enteral feeding catheters are commonly used to administer both nutritional feedings and oral forms of medications. Obstruction of the catheters is a major concern. OBJECTIVES: To study characteristics of obstruction of enteral feeding catheters in ICU patients and current knowledge and practices of ICU nurses of administering medications through such catheters. METHODS: A postcard invitation to participate in this descriptive survey was mailed to a random sample of 12,069 members of the American Association of Critical-Care Nurses. The 52-item investigator-designed questionnaire was mailed to the 1700 critical care nurses who agreed to participate; 1167 (68.6%) returned completed survey questionnaires. RESULTS: Nurses estimated that 33.8% of their patients received 8.9 doses of medication per day through the enteral feeding catheter. The rate of obstruction of the tube by medications was 15.6%. Crushed medications contributed to obstruction, although liquid forms of the medications often were available. Nurses' primary source of knowledge about administering medications through enteral feeding catheters was clinical practice (56.9%) and consultation with peers (21.7%); only 19% had had inservice training on the topic. Written agency guidelines varied considerably, and 74% of nurses used two or more techniques that were contrary to recommendations. Factors significantly associated with lower rates of obstruction of enteral feeding catheters included (1) assistance from the pharmacy service to ensure liquid forms of medications, (2) nurses' attendance at a relevant seminar or inservice training program, and (3) not routinely crushing and administering enteric-coated or sustained-release medications through the enteral feeding catheter. CONCLUSIONS: Collaboration between nursing and pharmacy services to ensure delivery of liquid medications and avoid use of crushed medications may reduce the high rate of catheter obstruction due to medications. Research-based guidelines and a more formal dissemination of information to nurses are needed.

Administration of medications through enteral feeding catheters

BACKGROUND

Enteral feeding catheters are commonly used to administer both nutritional feedings and oral forms of medications. Obstruction of the catheters is a major concern.

OBJECTIVES

To study characteristics of obstruction of enteral feeding catheters in ICU patients and current knowledge and practices of ICU nurses of administering medications through such catheters.

METHODS

A postcard invitation to participate in this descriptive survey was mailed to a random sample of 12,069 members of the American Association of Critical-Care Nurses. The 52-item investigator-designed questionnaire was mailed to the 1700 critical care nurses who agreed to participate; 1167 (68.6%) returned completed survey questionnaires.

RESULTS

Nurses estimated that 33.8% of their patients received 8.9 doses of medication per day through the enteral feeding catheter. The rate of obstruction of the tube by medications was 15.6%. Crushed medications contributed to obstruction, although liquid forms of the medications often were available. Nurses' primary source of knowledge about administering medications through enteral feeding catheters was clinical practice (56.9%) and consultation with peers (21.7%); only 19% had had inservice training on the topic. Written agency guidelines varied considerably, and 74% of nurses used two or more techniques that were contrary to recommendations. Factors significantly associated with lower rates of obstruction of enteral feeding catheters included (1) assistance from the pharmacy service to ensure liquid forms of medications, (2) nurses' attendance at a relevant seminar or inservice training program, and (3) not routinely crushing and administering enteric-coated or sustained-release medications through the enteral feeding catheter.

CONCLUSIONS

Collaboration between nursing and pharmacy services to ensure delivery of liquid medications and avoid use of crushed medications may reduce the high rate of catheter obstruction due to medications. Research-based guidelines and a more formal dissemination of information to nurses are needed.

[Intestinal permeability in alcoholic patients without liver damage]

BACKGROUND

Chronic alcoholism may increase intestinal permeability. However, there are few studies of intestinal permeability in chronic alcoholic subjects.

AIM

To study intestinal permeability in chronic alcoholic patients without clinical evidences of liver damage, during early abstinence, and in normal subjects.

METHODS

Thirty seven male subjects were studied, 18 controls and 19 alcoholics. All subjects underwent an anthropometric assessment and dietary history. Lactulose/mannitol test was performed during the third day of abstinence in alcoholics. After an 8 hour overnight fast, subjects drank 200 ml of a solution containing 5 g lactulose and 5 g mannitol. Subsequently, urine was collected during the following 5 hours, where both sugars were measured by gas chromatography.

RESULTS

Median values of lactulose/mannitol ratio were similar in alcoholics and controls (0.011, range 0.005-0.071 vs 0.014, range 0.005-0.027 respectively). However, absolute urinary excretion of both lactulose and mannitol was lower in alcoholics. There was no relationship between nutritional status and urinary excretion of lactulose, mannitol or lactulose/mannitol ratio.

CONCLUSION

In these alcoholic patients, no changes were observed in intestinal permeability.

[Results after two years of an alcoholic rehabilitation program]

BACKGROUND

Alcoholism is a serious public health problem in Chile and the best treatment strategy for this problem is far from being clear.

AIM

To assess the long term results of an alcoholism rehabilitation program.

PATIENTS AND METHODS

One hundred eighty two alcoholics admitted for treatment of their alcoholism were followed during two years in a special clinic. The effects of length of alcoholism, withdrawal symptoms on admission and the presence of histological liver damage on long term outcome were assessed using life table analysis.

RESULTS

During the two years period, 75% of patients were lost from control and 63% relapsed in their alcoholic ingestion. None of the above mentioned parameters had an effect on relapse or loss from follow up.

CONCLUSIONS

There are high attrition and failure rates and the length of alcoholism, degree of initial withdrawal and liver damage do not influence the long term results of this program.

[Markers of hepatic fibrogenesis in alcoholic patients]

BACKGROUND

An elevation of serologic markers of hepatic fibrogenesis has been reported in liver diseases of different etiologies. Among these, the N-terminal type III procollagen (P-III-P) and the P1 proteolytic fragment of laminin (P1 laminin) increase in alcoholic liver damage, in proportion to the progression of this condition.

AIM

To study serum levels of P-III-P and P1 laminin in asymptomatic alcoholics with and without liver damage and decompensated alcoholic cirrhotics, compared to normal controls.

METHODS

Serum P-III-P and laminin levels were measured in asymptomatic alcoholics during detoxification treatment. Liver biopsies were obtained, in order to detect liver damage, which was graded with a numeric score, considering values over 6 as severe damage. Serum fibrogenesis markers were also measured in a group of decompensated alcoholic cirrhotics.

RESULTS

P-III-P levels were significantly higher in cirrhotic patients compared to alcoholics with or without liver damage and to normal controls. Laminin was not different between groups. P-III-P did not correlate with histologic score in asymptomatic patients.

CONCLUSIONS

In this study P-III-P and P1 laminin were not usefull discriminators of severe liver damage among asymptomatic alcoholics; their levels were found to rise significantly only when liver disease has become clinically evident.