The role of exercise training and the endocannabinoid system in atherosclerotic plaque burden and composition in Apo-E-deficient mice.

INTRODUCTION: We investigated the effect of combining exercise training and treatment with an endocannabinoid receptor 1 inhibitor (Rimonabant) on atherosclerosis burden and composition. METHODS: Forty-eight apolipoprotein E-deficient (ApoE-/-) mice were kept on a 16-week high-fat diet. Mice were then placed on a normal diet and were randomized to the following groups with n=12 mice for 6 more weeks: 1) Control (Co) - no intervention; 2) Exercise (Ex) - exercise training on treadmill; 3) Rimonabant (Ri) - oral administration of rimonabant (10 mg/kg/day); or 4) Rimonabant+Exercise (RiEx) - combination of Ri and Ex groups treatment. At the end, all animals were sacrificed, and blood samples, as well as aortic root specimens, were obtained for histomorphometric analysis and quantification of the serum and plaque content of matrix metalloproteinases (MMPs). RESULTS: The mean plaque area was significantly smaller (RiEx: 43.18±1.72%, Ri: 44.66±3.1%, Ex: 49±4.10%, Co: 70.43±2.83%) in all active treatment groups relative to the Co group (p<0.01). Conversely, the relative concentrations of collagen and elastin were increased significantly across all treatment groups compared to Co (p<0.05). Immunohistochemical analysis revealed significantly reduced macrophage content within plaques after all interventions, with the most pronounced effect observed after combined treatment (RiEx: 9.4±3.92%, Ri: 15±2.45%, Ex: 19.78±2.79%, Co: 34.25±4.99%; p<0.05). Within plaques, the TIMP-1 concentration was significantly upregulated in exercise-treated groups. MMP-3 and MMP-9 concentrations were equivalently decreased in all three active treatment groups compared to controls (p<0.001). DISCUSSION: Both exercise and rimonabant treatments induced plaque regression and promoted plaque stability. The combined treatment failed to show additive or synergistic benefits relative to either intervention alone.

Adhesions and Healing of Intestinal Anastomoses: The Effect of Anti-Adhesion Barriers.

Background Postoperative adhesions are the result of aberrant peritoneal healing. As they are the leading cause of postoperative bowel obstruction, anti-adherence barriers are advocated for their prevention. This study looks into the effect of these biomaterials on the healing of intestinal anastomoses. Materials and Methods Thirty-three New Zealand White rabbits underwent laparotomy, transection of the terminal ileum, and creation of an end-to-end anastomosis. Animals were randomized into 3 groups: the Control group (n = 11); the Icodextrin group, receiving icodextrin 4% intraperitonealy (n = 11); and the HA/CMC group, having the anastomosis wrapped with a hyaluronic acid/carboxymethylcellulose film (n = 11). All animals were sacrificed on the seventh postoperative day. Macroscopic adhesions were graded and anastomotic strength was tested by the burst pressure. Histological healing was assessed in a semiquantitative way for the presence of ulceration, reepithelization, granulation tissue, inflammation, eosinophilic infiltration, serosal inflammation, and microscopic adhesions. Univariate and multivariate analysis was used. Results are given as medians with interquartile range. Results The median adhesion scores were the following: Control 1 (0-3), Icodextrin 0 (0-1), HA/CMC 0 (0-0), P = .017. The burst pressure did not differ between the groups; however, all except one bowel segments tested burst away from the anastomosis. The macroscopic and histological anastomotic healing was comparable in all 3 groups. A poor histological anastomotic healing score was associated with a higher adhesion grade (odds ratio = 1.92; 95% confidence interval = 1.06-3.47; P = .032). Conclusion Adhesion formation was inhibited by the materials tested without direct detrimental effects on anastomotic healing. Poor anastomotic healing provokes adhesions even in the presence of anti-adhesion barriers.

The complementary effects of atorvastatin and exercise treatment on the composition and stability of the atherosclerotic plaques in ApoE knockout mice.

AIM: This study aimed to investigate the effects of combined atorvastatin and exercise treatment on the composition and stability of the atherosclerotic plaques in apolipoproteinE (apoE) knockout mice. METHODS: Forty male, apoE-/- mice were fed a high-fat diet for 16 weeks. Thereafter, while maintained on high-fat diet, they were randomized into four (n = 10) groups for 8 additional weeks: Group CO: Control. Group AT: Atorvastatin treatment (10 mg/Kg/day). Group EX: Exercise-training on treadmill. Group AT+EX: Atorvastatin and simultaneous exercise training. At the study's end, plasma cholesterol levels, lipids and triglycerides were measured, along with the circulating concentrations of matrix-metalloproteinases (MMP-2,3,8,9) and their inhibitors (TIMP-1,2,3). Plaque area and the relative concentrations of collagen, elastin, macrophages, smooth muscle cells, MMP-2,3,8,9 and TIMP-1,2,3 within plaques were determined. Lastly, MMP activity was assessed in the aortic arch. RESULTS: All intervention groups showed a lower degree of lumen stenosis, with atheromatous plaques containing more collagen and elastin. AT+EX group had less stenosis and more elastin compared to single intervention groups. MMP-3,-8 -9 and macrophage intra-plaque levels were reduced in all intervention groups. EX group had increased TIMP-1 levels within the lesions, while TIMP-2 was decreased in all intervention groups. The blood levels of the above molecules increased during atherosclerosis development, but they did not change after the therapeutic interventions in accordance to their intra-plaque levels. CONCLUSION: The two therapeutic strategies act with synergy regarding the extent of the lesions and lumen stenosis. They stabilize the plaque, increasing its content in elastin and collagen, by influencing the MMP/TIMP equilibrium, which is mainly associated with the macrophage amount. While the increased MMP-2,-3,-8 -9, as well as TIMP-1 and TIMP-2 circulating levels are markers of atherosclerosis, they are not correlated with their corresponding concentrations within the lesions after the therapeutic interventions, and cannot serve as markers for the disease development/amelioration.

The effect of propranolol on aortic structure and function in normotensive rats.

INTRODUCTION: Beta-blocking agents are widely used for the treatment of many cardiovascular diseases. The effect of these agents, however, on the aortic wall structure and function has not been well defined. The present study was undertaken to investigate the effect of therapy with propranolol on wall structure and aortic function in rats. METHODS: 20 healthy Wistar rats (350-400 g) were assigned to a control group (n=8), with rats receiving only water and food, and an experimental group (n=12), in which 100 mg/kg/day propranolol was administered in the drinking water. Three months after initiation of treatment, aortic pressures and aortic pulse wave velocity (PWV) were measured using high-fidelity Millar catheters. Extensive histopathologic studies were performed in the wall of the descending thoracic aorta. RESULTS: Systolic, mean, diastolic, and pulse pressure were significantly lower in the propranolol-treated rats compared to controls (p<0.05). For any given systolic, mean, and pulse pressure, PWV was greater in the propranolol-treated animals (p<0.05). The heart rate was lower and the response to isoproterenol infusion was less in the propranolol-treated animals. Smooth muscle content was decreased and collagen content was increased in the aortic wall of the propranolol-treated animals compared to controls. CONCLUSIONS: Long-term propranolol administration elicits an increase in PWV adjusted for aortic pressure. This may be related to accumulation of collagen in the aortic wall at the expense of smooth muscle cells. The aortic stiffening may explain some of the reported data, suggesting that the effect of ß-blockade therapy in patients with arterial hypertension may be inferior to other pharmacologic agents.

Effects of exercise training on the severity and composition of atherosclerotic plaque in apoE-deficient mice.

AIM: To investigate the effects of exercise on atherosclerotic plaque composition, the concentration of matrix metalloproteinases (MMPs) in the atherosclerotic plaque and the systemic circulation. METHODS: Ninety apolipoprotein E-deficient (apoE(-/-)) mice (45 male) were randomized to the following groups (n=15 each): control male/female; sedentary male/female; exercise male/female. Mice were kept on a 16-week high-fat diet. Subsequently, the control groups were sacrificed, while the rest of the animals were placed on a normal diet for 6 more weeks. During the latter period, the exercise groups were trained daily on treadmill. At the end of the study, mice were euthanized, and blood samples as well as aortic root specimens were obtained. RESULTS: Compared to control and sedentary animals, exercise training reduced atherosclerotic plaques (-30%; p<0.01) and increased elastin and collagen content in both genders (p<0.05). Body weight or lipid profile did not change significantly. Decreased macrophages and MMP-9 as well as increased tissue inhibitor of metalloproteinases 1 (TIMP-1) levels were observed in the atherosclerotic plaques of the exercise-treated groups (p<0.05). Plasma concentrations of MMP-9 decreased, while plasma TIMP-1 levels increased in the exercise compared to control and sedentary groups (p < 0.05). CONCLUSIONS: Exercise training had a favorable effect on the size and composition of the atherosclerotic plaque in apoE(-/-) mice, associated with suppressed MMP activity.

Local hemodynamics and intimal hyperplasia at the venous side of a porcine arteriovenous shunt.

Venous anastomotic intimal hyperplasia (IH) observed in the arteriovenous shunt (AVS) has been associated with disturbed hemodynamics. This study aims to correlate hemodynamics with wall histology and wall mechanics by examining the flow field in AVS with computational fluid dynamics using experimental data taken from in vivo experiments. Input data to the computational model were obtained in vivo one month after AVS creation; adjacent vessels were submitted to histological and mechanical examination. The 3-D shunt geometry was determined using biplane angiography. Ultrasound measurements of flow rates were performed with perivascular flow probes and pressures were recorded through intravascular catheters. These data were considered as boundary conditions for calculation of the unsteady flow field. Numerical findings are suggestive of strong Dean vortices toward both vein flow exits, verified by color Doppler. The high wall shear stresses (WSSs) and their gradients appear to be related to areas of IH and vessel wall stiffening, as evidenced in preliminary histological and mechanical studies of the venous wall. Additionally, suture line hyperplasia seems to be aggravated by the high WSS gradients noted at the transition line from graft to vein.

Time-course of mechanical changes of the rat aorta following chronic beta-blocker treatment.

INTRODUCTION: The mechanical properties of the aorta play an important role in arterial homeostasis and constitute a prognostic factor in cardiovascular disease. This study determined the time-course of mechanical changes of the thoracic aorta following prolonged beta (beta)-blocker treatment. METHODS: Sixty-six healthy male Wistar rats were randomized to 4 groups. Group A was divided into subgroups A1 (n=6), A2 (n=6), and A3 (n=6), with animals receiving only water. In groups B (n=16), C (n=16), and D (n=16), propranolol was added to the drinking water (100 mg/kg/day). Animals of groups A1 and B, A2 and C, and A3 and D were sacrificed after 1, 2, and 3 months. The effect of beta-blockade was assessed by heart rate changes in response to isoproterenol infusion. The thoracic aorta was excised and submitted to mechanical testing. Regression analysis was performed to evaluate the relationship between elastic modulus and stress for low (part I), physiologic (part II), and high (part III) stresses. RESULTS: Data from subgroups A1, A2, and A3 were pooled together and were used as a control. Differences were found in the regression parameters of parts II and III between the propranolol-treated groups and controls, indicating that the aorta was stiffer in propranolol-treated rats compared to controls at physiologic stresses, and at physiologic and high strains. Changes developed progressively with the duration of treatment. No differences were found in the regression parameters of part I, indicative of non-varying elastic modulus, i.e. stiffness, at low stresses and strains. CONCLUSIONS: Chronic blockade of beta-adrenergic receptors induces changes in the mechanical properties of the thoracic aorta. Aortic stiffening in response to beta-blocker treatment may be of great clinical significance.

The effects of hypothyroidism on the mechanical properties and histomorphological structure of the thoracic aorta.

This experimental study investigates the effects of hypothyroidism on the descending thoracic aorta. Hypothyroidism was induced in 20 male Wistar rats by administering 0.05% of 6-n propyl 2-thiouracil (PTU) in their drinking water for 8 weeks. Euthyroid rats were used as controls. Animals were sacrificed and longitudinal strips of the descending aorta were subjected to various preselected levels of stress in a uniaxial tensile-testing device. Analysis of stress-strain, elastic modulus-strain curves disclosed significant differences between groups, indicative of stiffer aortas in hypothyroid animals at the upper physiologic and higher levels of pressure. Remodeling of the aortic wall of hypothyroid animals revealed significant histological changes. The thoracic aorta of hypothyroid rats compared with that of euthyroid ones became stiffer at high strains, including the upper physiologic range, loosing part of its distensibility. Hypothyroidism was also associated with diameter enlargement and substantial lengthening of the aorta.

Effects of rosiglitazone and metformin treatment on apelin, visfatin, and ghrelin levels in patients with type 2 diabetes mellitus.

Visfatin, ghrelin, and apelin are the most recently identified adipocytokines; but their response to insulin-sensitizing agents is poorly clarified. We aimed to assess the differential effects of either rosiglitazone or metformin monotherapy on the aforementioned adipocytokines in patients with type 2 diabetes mellitus (T2DM). One hundred T2DM patients (30 men, 70 women), with poor glycemic control (glycosylated hemoglobin >6.5%) while taking 850 mg of metformin daily, were enrolled. All participants were randomized to receive either adjunctive therapy with rosiglitazone (8 mg/d, n = 50) or the maximum dose (2550 mg/d) of metformin (MET group, n = 50). Anthropometric parameters, glycemic and lipid profile, high-sensitivity CRP (hs-CRP), insulin resistance (homeostasis model assessment of insulin resistance index [HOMA-IR]), visfatin, ghrelin, and apelin were assessed at baseline and after 14 weeks of therapy. Both rosiglitazone and metformin led to similar, significant improvement in glycemic profile and apelin levels, whereas lipid parameters, fat mass, and visfatin remained almost unaffected (P > .05). Insulin resistance was significantly attenuated in both groups, but to a lesser degree in the MET group (P = .045). Rosiglitazone-treated patients experienced a significant decrease in hs-CRP and systolic blood pressure compared with baseline values and those of the MET group (P < .05). Besides, rosiglitazone treatment considerably increased plasma ghrelin (3.74 +/- 1.52 ng/mL) in comparison with either baseline (P = .034) or metformin monotherapy values (-2.23 +/- 1.87 ng/mL, P = .008). On the other hand, the MET group, rather than the rosiglitazone group, had decreased body mass index (-0.79 +/- 0.47 vs 0.56 kg/m(2), P = .009). The aforementioned changes in apelin and ghrelin were independently associated with HOMA-IR changes. Both rosiglitazone and metformin favorably changed glycemic indexes and apelin levels. The addition of rosiglitazone seemed to confer greater benefits in ghrelin, hs-CRP, systolic blood pressure, and HOMA-IR regulation than metformin monotherapy. Although these results reflect improvement in cardiovascular risk profile, the overall clinical importance of insulin sensitizers must be further assessed.

Beta-adrenergic receptor blockade and prostate peptide growth factor expression in the rat.

BACKGROUND AND AIM: In the rat prostate, beta-adrenoreceptor (beta-AR) stimulation does not alter basal prostatic tone but may inhibit alpha1-AR-mediated, field stimulation-induced or receptor-independent contractile responses. The present study was designed to assess the alteration of basic fibroblast growth factor (bFGF) and transforming growth factor-beta (TGFbeta) expression in the rat ventral prostate in response to beta-AR blockade with propranolol. RESULTS: At sacrifice, body weight as well as ventral prostate weight and prostate morphology were not significantly affected by propranolol treatment. Stromal elements and the majority of prostatic epithelial cells in control animals demonstrated positive staining for the anti-bFGF antibody, while positive staining for TGFbeta was seen only in epithelial cells. Propranolol treatment resulted in considerable decrease of bFGF staining intensity in both stromal and epithelial cells, while the immunostaining pattern for TGFbeta was almost abolished. RESULTS AND CONCLUSIONS: The results from this study provide evidence to suggest that prolonged propranolol treatment affects peptide growth expression in the rat ventral prostate as in other tissues, and confirms the notion that autonomic nervous system controls, at least partly, prostate gland functional characteristics. Moreover, it may also affect prostate homeostasis by intervening in stromal-epithelial interaction through alterations in the expression of peptide growth factors without affecting prostate volume.

Exercise training ameliorates the effects of rosiglitazone on traditional and novel cardiovascular risk factors in patients with type 2 diabetes mellitus.

The aim of the study was to investigate the effects of rosiglitazone and/or exercise training on novel cardiovascular risk factors in patients with type 2 diabetes mellitus. One hundred overweight/obese type 2 diabetes mellitus patients, with inadequate glycemic control (hemoglobin A(1c) >7%) despite combined treatment with gliclazide plus metformin, were randomized using a 2 x 2 factorial design to 4 equivalent (n = 25) groups, as follows: (1) CO: maintenance of habitual activities, (2) RSG: add-on therapy with rosiglitazone (8 mg/d), (3) EX: adjunctive exercise training, and (4) RSG + EX: supplementary administration of rosiglitazone (8 mg/d) plus exercise training. No participant had diabetic vascular complications or was receiving lipid-lowering therapy. Anthropometric parameters, cardiorespiratory capacity, glycemic and lipid profile, apolipoprotein (apo) A-I, apo B, interleukin (IL)-10, IL-18, insulin resistance, and blood pressure were measured before and after 12 months of intervention (P < .05). Both RSG and EX groups significantly reduced glycemic indexes, insulin resistance, blood pressure, and IL-18, whereas they significantly increased high-density lipoprotein, cardiorespiratory capacity, and IL-10, compared with CO group (P < .05). Besides this, exercise-treated patients conferred a remarkable down-regulation in the rest of lipid parameters (total cholesterol, low-density lipoprotein cholesterol, triglycerides, apo B) and body fat content (P < .05) in comparison with CO group. On the other hand, RSG group rather than CO group considerably increased apo A-I levels and body mass index (P < .05). Notably, the combined treatment group yielded pronounced beneficial changes in glycemic indexes, lipid profile, insulin resistance, blood pressure, IL-10, IL-18, apo A-I, and apo B (vs CO group, P < .05). Furthermore, the addition of exercise to rosiglitazone treatment counteracted the drug-related negative effects on body weight, low-density lipoprotein, and total cholesterol. Rosiglitazone plus exercise training elicited additive effects on body composition, glycemic control, and traditional and novel cardiovascular risk factors in type 2 diabetes mellitus patients, indicating complementary effects.

Segmental differences of aortic function and composition: clinical implications.

INTRODUCTION: Aortic function is an important determinant of pressure and flow in the entire cardiovascular system. This study aimed at evaluating segmental differences of aortic function and composition, in order to understand their clinical implications. METHODS: The thoracic aorta from each of 20 healthy pigs was divided into four and the abdominal into three segments. From the stress-strain curves, relationships between elastic modulus and stress were obtained for low (part I), physiologic (part II) and high (part III) stresses. Linear regression analysis was performed. RESULTS: No differences were found in the intercepts and slopes for part I. Significant differences were found in the intercepts and slopes between the thoracic and abdominal segments for part II, and in the slopes for part III, suggesting that the distal segments became progressively stiffer. Histologic examination disclosed higher concentrations of elastin in the proximal and collagen in the distal aortic wall. Aortic wall thickness reduced from proximal to distal aorta. Multiple regression analysis showed good correlations between elastic moduli and either elastin in part I (r=0.640) or collagen in part III (r=0.803). CONCLUSIONS: The elastic properties and composition vary in different aortic segments. These differences should be taken into consideration when aortic function is determined in clinical practice.

The mechanical performance and histomorphological structure of the descending aorta in hyperthyroidism.

Thyroid hormones decrease systemic vascular resistance by directly affecting vascular smooth muscle relaxation. There is limited literature about their effect on the mechanical performance of the aortic wall. Therefore, the authors determined the influence of hyperthyroidism on the mechanical properties and histomorphological structure of the descending thoracic aorta in rats. Severe hyperthyroidism was induced in 20 male Wistar rats by administering L-thyroxine (T(4)) in their drinking water for 8 weeks; age-matched normal euthyroid rats acted as controls. Animals were sacrificed, and the mechanical and histomorphometrical characteristics of the descending thoracic aorta were studied. The aortic wall of hyperthyroid rats was stiffer than that of euthyroid animals at the upper physiologic levels of stress or strain (p < 0.05) but less stiff at the lower physiologic and lower levels (p < 0.05). The aorta of hyperthyroid animals compared with that of euthyroid ones showed an increase of the internal and external diameters (p < 0.05), the media area (p < 0.05), the number of smooth muscle cell nuclei (p < 0.05), and the collagen density (p < 0.05) and a decrease in the elastin laminae thickness (p < 0.001) and elastin density (p < 0.001). In hyperthyroid rats, the aortic wall was stiffer at the upper physiologic and higher levels of stress and strain. These changes correlated with microstructural changes of the aortic wall. The coexistence of hyperthyroidism with disease states or clinical conditions that predispose to increased arterial pressure may be associated with increased arterial stiffness and have undesirable consequences on the mechanical performance of the thoracic aorta and hemodynamic homeostasis. These changes could lead to an increased risk for developing vascular complications.

Eradication of Helicobacter bilis and H. hepaticus from infected mice by using a medicated diet.

Infection of laboratory mice with Helicobacter spp. is a serious problem for many laboratory animal facilities worldwide. Rederivation and antibiotic treatment are two of the most common methods used to eliminate the bacterial infection from rodent colonies. Forty-seven newly imported mice were suspected to be positive for Helicobacter infection based on PCR analysis of pooled fecal samples from sentinel animals. We treated the mice with a medicated feed containing four antibiotic compounds (amoxicillin, clarithromycin, metronidazole, omeprazole). After eight weeks of continuous administration the animals were negative for H. bilis and H. hepaticus. Frequent retesting of the animals for up to one year proved that the mouse colony remained negative for Helicobacter spp.

A structural basis for the aortic stress-strain relation in uniaxial tension.

A constitutive law that includes three analytical expressions was recently proposed to approximate the low, physiologic, and high-stress parts of the aortic stress-strain relation in uniaxial tension, consistent with the biphasic nature of the aortic wall under passive conditions. This consistency, and the fact that previous phenomenological uniaxial laws have only indirectly been related to vessel wall structure, motivates the investigation of the structural basis underlying the newly proposed three-part constitutive law. For this purpose, longitudinally oriented aortic strips were fixed in Karnovsky's solution, while subjected to various pre-selected levels of uniaxial tensile stress. Light microscopy examination disclosed that the elastic lamellae gradually unfolded at low and were almost straight at physiologic and high stresses, while collagen fibers reoriented in the longitudinal axis at low, started uncoiling at physiologic, and straightened massively at high stresses. In the circumferential sections, the elastic lamellae and the circumferentially distributed collagen bundles remained wavy at all levels of longitudinally applied stress. These microstructural changes suggest that elastin becomes load-bearing at low, and collagen at physiologic but mostly at high stresses, so that the first and third parts of the constitutive law are in turn due to the presence of elastin and collagen alone, and the second due to both elastin and collagen. The structural basis of this constitutive law allows physically significant interpretation of its parameters, offering insight into how the aortic microstructure determines the macromechanical response.

Post-vagotomy mechanical characteristics and structure of the thoracic aortic wall.

This study assessed the long-term effect of vagotomy on the structure and passive mechanical characteristics of the thoracic aorta under a wide range of stresses in vitro. Eight healthy Landrace pigs underwent bilateral vagotomy distal to the origin of the recurrent laryngeal nerve, and 10 pigs were sham-operated. Three months post-surgery, the aorta was excised and specimens from the ascending aorta, arch, and descending thoracic aorta were subjected to histomorphometrical evaluation and uniaxial tensile-testing until failure. Elastic modulus-stress data were plotted and submitted to regression analysis. Structural remodeling after vagotomy was characterized as vascular growth in the ascending aorta and arch, and as thinning in the descending thoracic aorta. In the aortic segments of vagotomized animals, the area density of elastin and collagen was increased, but smooth muscle density was decreased. Similar differences in regression parameters and failure strength between groups were found in all aortic segments, indicating that the vessel wall was stiffer and stronger in vagotomized animals. In the clinical setting, disease states or drugs blocking the regulatory role of the vagi nerves on the aortic wall may have undesirable consequences on the mechanical performance of the thoracic aorta, and therefore on hemodynamic homeostasis.

Immunomodulatory intervention in sepsis by multidrug-resistant Pseudomonas aeruginosa with thalidomide: an experimental study.

BACKGROUND: Thalidomide is an inhibitor of tumour necrosis factor-alpha (TNFalpha) that has been proven effective for the treatment of experimental sepsis by Escherichia coli. It was tested whether it might behave as an effective immunomodulator in experimental sepsis by multidrug-resistant (MDR) Pseudomonas aeruginosa. METHODS: Sepsis was induced by the intraperitoneal injection of 1 x 10(8) cfu/kg inoculum of the test isolate in a total of 10(9) Wistar rats divided in three groups as follows: group A controls; group B administered seed oil 30 minutes before bacterial challenge; and group C administered 50 mg/kg of thalidomide diluted in seed oil 30 minutes before bacterial challenge. Blood was sampled for estimation of endotoxins (LPS), TNFalpha, interferon-gamma (IFNgamma), nitric oxide (NO) and malondialdehyde (MDA). LPS was measured by the QCL-1000 LAL assay, TNFalpha and IFNgamma by ELISA, NO by a colorimetric assay and MDA by the thiobarbiturate assay. RESULTS: Mean (+/- SE) survival of groups A, B and C were 18.60 +/- 1.84, 12.60 +/- 0.60 and 30.50 +/- 6.62 hours (p of comparisons A to C equal to 0.043 and B to C equal to 0.002). Decreased TNFalpha and NO levels were found in sera of animals of group C compared to group A. Plasma levels of LPS, MDA and IFNgamma did not differ between groups. CONCLUSION: Intake of thalidomide considerably prolonged survival in experimental sepsis by MDR P. aeruginosa an effect probably attributed to decrease of serum TNFalpha.

Clarithromycin: immunomodulatory therapy of experimental sepsis and acute pyelonephritis by Escherichia coli.

The potency of clarithromycin as immunomodulator was assessed in an experimental model of sepsis based on acute pyelonephritis by susceptible Escherichia coli. 55 rabbits were utilized; 5 for preliminary pharmacokinetic study and 50 for treatment. The latter were divided into 5 groups of treatment, A: controls; B: clarithromycin pretreatment; C: amikacin pretreatment; D: clarithromycin treatment on presentation of pulmonary oedema; and E; amikacin treatment on presentation of pulmonary oedema. Survival was recorded; tumour necrosis factor-alpha (TNFalpha), and malondialdehyde (MDA) were estimated in serum; activities of caspase-3 in monocyte cytosolic extracts were studied; and bacterial counts made in various organs. Median survival of animals of groups A, B, C, D and E was 1.0, 21.0, 12.5, 2.0 and 5.0 d, respectively. TNFalpha and MDA and monocyte caspase-3 activity of group A increased over time; no increases were detected in groups B and C. Concentrations of MDA and activities of monocytic caspase-3 were decreased after administration of clarithromycin in group D, an effect not occurring in group E. Bacterial load was decreased in renal tissue of group D compared to group A. It is concluded that intravenous clarithromycin might constitute a promising immunomodulator in sepsis even in the advent of pulmonary oedema.

n-6 polyunsaturated fatty acids enhance the activities of ceftazidime and amikacin in experimental sepsis caused by multidrug-resistant Pseudomonas aeruginosa.

Recent in vitro and ex vivo studies disclosed an enhancement of the activity of antimicrobials on multidrug-resistant Pseudomonas aeruginosa by n-6 polyunsaturated fatty acids (PUFAS); therefore their effect was evaluated in experimental sepsis in 60 rabbits. Solutions of gamma-linolenic acid (GLA) and arachidonic acid (AA) were administered intravenously with ceftazidime and amikacin in rabbits with sepsis caused by one multidrug-resistant isolate. Therapy was started after bacterial challenge in five groups comprising 12 animals in each group: A, normal saline; B, antimicrobials; C, 99% ethanol and antimicrobials; D, GLA and antimicrobials; and E, AA and antimicrobials. Blood was sampled for the estimation of levels of endotoxins in serum (lipopolysaccharide), leukocytes, tumor necrosis factor alpha (TNF-alpha) and antimicrobials. Animals were sacrificed 210 min after bacterial challenge for tissue cultures. All animals had considerable endotoxemia and evolved leukopenia. The number of viable cells in blood, lung, and mesenteric lymph nodes was significantly reduced in groups D and E compared to that in other groups. Levels of antimicrobials in serum were inadequate to achieve bacterial killing due to the level of resistance. n-6 PUFAs did not influence TNF-alpha. It is concluded that intravenous coadministration of n-6 PUFAs and antimicrobials enhanced antimicrobial bacterial killing in experimental sepsis caused by multidrug-resistant P. aeruginosa.

The influence of indomethacin co-administration on ofloxacin levels in plasma and cerebrospinal fluid in rats.

The possible increase of ofloxacin levels in serum and cerebrospinal fluid (CSF) by concomitant indomethacin administration was investigated in 120 healthy adult rats. The animals were administered intramuscular doses of ofloxacin 30 mg/kg alone (Group A, n = 60) or with indomethacin 2 mg/kg (Group B, n = 60). Blood and CSF samples were obtained from both groups at 30, 45, 60 and 90 min post-administration. Concentrations of ofloxacin were estimated using a microbiological assay. Co-administration of indomethacin did not affect plasma levels of ofloxacin significantly; however, higher levels were found in all CSF samples after co-administration with indomethacin, particularly after 90 min with 0.59 microg/ml versus zero median values when only ofloxacin was administered (P = 0.05). No central nervous system adverse effects were observed clinically. No correlation between levels of ofloxacin in plasma and CSF could be established either in rats administered only ofloxacin or in rats administered both drugs. The presented pharmacokinetic findings revealed that co-administration of ofloxacin and indomethacin may result in protracted quinolone levels in the CSF. However, the absence of significant correlation between concentrations of ofloxacin in plasma and CSF upon co-administration of indomethacin, as well as of central nervous system adverse effects, make the probability of an epileptogenic interaction between them unlikely. These results merit further clinical evaluation.