Effects of antimicrobial agents on spontaneous and endotoxin-induced cytokine release of human peripheral blood mononuclear cells

 Because the immunomodulatory effects of antibiotics could possibly influence the degree of the systemic and local response to infection, knowledge of their intrinsic influence on the host's inflammatory response appears to be essential. Therefore, this study investigated the effects of frequently used antimicrobial agents (β-lactams, quinolones gentamicin, vancomycin and metronidazole) on the in-vitro tumor necrosis factor (TNF)-α and interleukin (IL)-6 production of isolated human peripheral blood mononuclear cells (PBMNC), cultured with or without endotoxin, in comparison with those effects obtained in a whole-blood assay system. In the presence of ciprofloxacin, ofloxacin, gentamicin, vancomycin, and metronidazole, a significant inhibition of the endotoxin-stimulated TNF-α production of human peripheral blood mononuclear cells (PBMNC) was found at therapeutic levels. Only ofloxacin showed a significant inhibitory influence on the endotoxin-induced IL-6 production of PBMNC. In the whole-blood assay, significant effects were not detectable. None of the antibiotics showed cytotoxicity. It is concluded that, at present, the direct immunological effects of antibiotics should be interpreted carefully with regard to the experimental conditions, and regardless of the therapeutic implications. To assess the potential direct immunomodulatory effect of antimicrobial agents, different cell culture procedures should be used. Received: October 19, 2001 / Accepted: February 15, 2002     

Ischemic necrosis of the lunate. The value of nuclear spin tomography in comparison to conventional roentgen studies

Conventional radiographs do not always make it possible to confirm a diagnosis of ischemic necrosis of the lunate in the early stages of disease. For these doubtful cases MRI is justifiable in addition, to diagnose or to rule out ischemic necrosis of the lunate.     

Down-regulation of inducible nitric oxide synthase (iNOS) in rat with congenital hydronephrosis

BACKGROUND: Most of our knowledge concerning obstructive uropathy has been derived mainly from surgically manipulated animal models, and the pathogenesis of congenital obstructive hydronephrosis is not fully elucidated. Nitric oxide (NO) acts as an important biological modulator with diverse physiological functions, which can be either toxic or protective depending on the situation. NO is synthesized from l-arginine by nitric oxide synthase, and in the kidney iNOS is expressed spontaneously. The aim of our study is to investigate the expression of iNOS protein and its relationship with tubulointerstitial fibrosis and tubular cell apoptosis in congenital hydronephrosis. METHODS: We conducted histological studies on 18 kidneys of six-week-old-rats from an inbred colony of congenital hydronephrosis with reference to the histological grading of the affected kidney, tubulointerstitial fibrosis, renal tubular atrophy, and tubular cell apoptosis. Renal transforming growth factor-beta1 (TGF-beta1) level was determined by a sandwich ELISA assay and the expression of iNOS was analyzed by western blotting. RESULTS: Most of the hydronephrotic kidneys were markedly enlarged with dilatation of the collecting system, parenchymal thinning, tubular atrophy, interstitial infiltration and fibrosis. Renal TGF-beta1 level was higher in hydronephrotic kidneys than normal control kidneys (364.81 +/- 52.60 vs. 221.19 +/- 22.53 pg/mg protein, P < 0.05). Tubular apoptotic score in hydronephrotic kidneys was also significantly higher than in the normal control kidneys (1.97 +/- 0.42 vs. 0.14 +/- 0.02/HPF, P < 0.01). The expression of iNOS protein was lower in the affected kidneys compared with the normal control kidneys (8.79 +/- 0.78 vs. 14.00 +/- 0.83 arbitrary unit, P < 0.01). There was a negative correlation between iNOS expression and histological grading in congenital hydronephrosis. The iNOS expression also correlated negatively with renal interstitial fibrosis, TGF-beta1 level and tubular cell apoptosis. CONCLUSION: Our study confirmed the down-regulation of iNOS expression in affected kidneys from rats with congenital hydronephrosis, in which the cytoprotective effect of NO may be lost or weakened.     

In vivo effects of hypothermia on the microcirculation during extracorporeal circulation.

OBJECTIVE: Induced hypothermia has been shown to be protective during cardiac surgery, but also in traumatic, ischemic, burn, and neurological injury. In previous in vivo animal experiments, we documented increased leukocyte/endothelial (L/E) cell interaction following normothermic extracorporeal blood circulation (ECC). This study was carried out to investigate whether reduced core temperature during ECC affects the damage to the microcirculation as evidenced by leukocyte adherence and edema formation. METHODS: Intravital fluorescence microscopy was used on the dorsal skinfold chamber preparation in Syrian golden hamsters. ECC was introduced via a micro-rollerpump (1 ml/min) and a 60 cm silicon tube (1mm inner diameter) shunted between the carotid artery and the jugular vein after application of 300IE Heparin/kg per body weight. Experiments were performed in chronically instrumented, awake animals (age 10-14 weeks, weight 65-75 g). Animals of the experimental group were cooled to 18 degrees C body temperature while ECC, followed by a rewarming period (n=7), controls experienced ECC under normothermia (37 degrees C, n=7). RESULTS: 30 min ECC at 18 degrees C resulted in a decrease of rolling and adherent leucocytes (stickers) in postcapillary venules after 1, 4 and 8h compared with the control group (119+/-46 vs. 274+/-113 n/mm2, P<0.05, mean+/-SD; n=7 in each group). Functional capillary density was significantly reduced during hypothermia (80+/-16 vs. 148+/-16 cm/cm2, P<0.05), but restored after rewarming. In contrast, edema formation was markedly increased during hypothermia. CONCLUSIONS: Hypothermia during ECC significantly reduced L/E cell interaction in the early post-ECC period. Hypothermia markedly reduced microvascular perfusion, but was completely restored upon rewarming. Despite a reduced number of adherent leukocytes, no protection of endothelial barrier function was seen as a consequence of induced hypothermia.     

Tissue characterization of symptomatic and asymptomatic disc herniations by quantitative magnetic resonance imaging

The purpose of this investigation was to determine differences in tissue composition of symptomatic and asymptomatic disc herniations as reflected in T₁ and T₂ relaxation times (quantitative magnetic resonance investigation of the lumber spine. The longitudinal and transverse magnetic rlaxation times (T₁ and T₂, respectively) were calculated from a set of 20 images obtained with five single-slice/multi-echo sequences at different repetition time values on a commercial whole-body system (1.5 T). Twenty-two symptomatic and asymptomatic disc herniations could be matched according to age, gender, disc level, and the extent of herniation (protrusion or extrusion) and were compared with regard to T₁ and T₂ relaxation times. Symptomatic disc herniations exhibited significantly (p_T1 < 0.04 and p_T2 < 0.003) shorter T₁(ΔT₁:–182.1 milliseconds, ?15%) and T₂(ΔT₂: ?11.0 milliseconds, ?21%) relaxation times than matched asymptomatic herniations. Symptomatic disc herniations also exhibited more advanced disc degeneration as graded by Pearce's criteria (p < 0.01). These results suggest that symptomatic and morphologically matched asymptomatic disc herniations differ with regard to disc matrix composition.     

Addition of sulfonylurea to insulin treatment in poorly controlled type II diabetes. A double-blind, randomized clinical trial

This study examined the potential beneficial effects of the addition of a second-generation sulfonylurea to insulin therapy for poorly controlled type II diabetes. A randomized, double-blind, crossover experimental design was utilized in 16 type II diabetic patients for a period of eight months. Treatment with glyburide, 20 mg/d (plus insulin), compared with placebo (plus insulin) resulted in a significant reduction in mean basal glucose (232 +/- 12 vs 262 +/- 11 mg/dL [12.8 vs 14.4 mmol/L]) and hemoglobin A1C (10.2% +/- 0.5% vs 10.9% +/- 03%) concentrations. Concomitant with this change, basal C-peptide and free insulin values increased with glyburide therapy, but this pharmacological agent did not alter the ability of the patient's erythrocytes to bind insulin. We conclude that in type II diabetic subjects receiving more than 28 units of insulin per day, the addition of glyburide results in a marginal, but statistically significant improvement in basal glucose concentration, but not in glucose tolerance as assessed by integrated glucose concentration. Whether this small improvement in glycemia is worth the additional cost of sulfonylureas or the risk of drug side effects is not known.     

In vivo effects of nifedipine and BAY 1 8201 on ceruletide induced gallbladder contraction

Studies in animals suggest that calcium channel blockers may influence gallbladder contraction. In order to study possible actions in man we examined by ultrasonography the effects of two dihydropyridine derivatives, i.e. nifedipine (20 mg p. o.) and BAY 1 8201 (100 mg p.o.) on ceruletide induced human gallbladder contraction in 9 healthy male volunteers in a randomized, double-blind, three fold crossover study (latin square design). Blood samples for the measurement of plasma drug concentrations were drawn before and at regular intervals up to 8 h after drug ingestion. Ceruletide decreased gallbladder volumes by 52.1 +/- 8.2% (mean +/- 1 SEM) after nifedipine, 53.1 +/- 8.1% after BAY 1 8201 and by 59.3 +/- 10.1% after placebo (NS). Peak plasma concentrations of 53.7 x/: 2.3 ng/ml (geometric mean x/: geometric standard deviation) and of 35.5 x/: 1.5 ng/ml were reached after oral application of nifedipine and BAY 1 8201, respectively. We conclude that human gallbladder contraction in response to ceruletide is not markedly influenced by dihydropyridine derivates in the dosages used in this study. The results reported here stress the importance of calcium released from intracellular stores for the contractility of smooth muscle in the human gallbladder.     

Deleterious effects of oxygen during extracorporeal circulation for the microcirculation in vivo.

OBJECTIVE: Clinical complications arising from extracorporeal circulation (ECC) have been linked to disturbances in the microcirculation. Hyperoxia, a mainstay of supportive treatment, is clinically used for a variety of pathological states. In previous in vivo animal experiments we found increased leukocyte/endothelial (L/E) cell interaction following ECC due to oxygen derived free radicals. This study was carried out to investigate the link between arterial pO2 during ECC and the potential damage to the microcirculation, supposedly caused by oxygen derived radicals. METHODS: Intravital fluorescence microscopy was used on the dorsal skinfold chamber preparation in syrian golden hamsters. ECC was introduced via a micro-rollerpump (0.7 ml/min) and a 60 cm silicon tube (1 mm inner diameter) shunted between the carotid artery and the jugular vein after application of 300 IE Heparin/kg/bw. Experiments were performed in chronically instrumented, awake animals (age: 10-14 weeks, weight: 65-75 g). Control inspired room air, experimental group 1 inspired 100% oxygen, group 2 received 100% oxygen and 2000 IE of Heparin i.v. (n=7/group), that releases endothelial bound superoxide dismutase, a natural scavenger of oxygen derived free radicals in the hamster. Results: Normobaric inhalation of 100% oxygen increased arterial pO2 from 64+/-8.1 mmHg to 512+/-124 mmHg (P<0.05 vs. baseline). ECC under 100% oxygen reduced functional capillary density (FCD) to 70% of baseline values 8 h after ECC (P<0.05). Adherent leukocytes in postcapillary venules and arterioles increased significantly (P<0.05). 2000 IE Heparin prevented the reduction in FCD and decreased the number of adherent leukocytes. CONCLUSIONS: Reduction in FCD, increased leukocyte adherence to the microvascular endothelium of postcapillary venules and arterioles under hyperoxia compared to ECC under room air conditions, demonstrates harmful effects of oxygen during ECC in vivo. A high dose of Heparin enhances functional capillary density, thus attenuating the microvascular dysfunction/damage in the period after ECC.