The protective effects of hormonal suppression by a gonadotropin-releasing hormone agonist or an oral contraceptive on the decreased ovarian reserve in female rats exposed to isotretinoin

OBJECTIVE

The objective of our study was to evaluate whether ovarian suppression by two different hormonal methods may spare the ovary the cytotoxic effects of isotretinoin in a rat model.

MATERIALS AND METHODS

Four groups (n=8 Sprague-Dawley albino rats per group) were studied: control (Group I), 7.5 mg/kg/day isotretinoin (Group II), isotretinoin plus the combination of 0.030 mg ethinyl estradiol/0.15 mg levonorgestrel (combined oral contraceptive, COC), and isotretinoin plus 100 μg (microgram) leuprolide acetate (GnRHa) (Group III and IV, respectively). Four rats from each group were decapitated on the 30th day of treatment, and the remaining rats were decapitated on the 30th day of untreated follow-up. Serum anti-Mullerian hormone (AMH) concentrations, healthy and atretic follicle numbers, and apoptotic activity of follicles in oophorectomy specimens were compared between the groups.

RESULTS

There were no significant differences in AMH levels among the study groups before, immediately after (first month), and one month after their last medication (second month) (p=0.08, 0.47, and 0.08, respectively). At the end of the first month, the control group had a higher median count of healthy primordial follicles compared to the study groups: 13.5 (8-22), 5.5 (3-11), 6 (2-13), and 1 (0-1) in control, isotretinoin, isotretinoin+COC, and isotretinoin+GnRHa groups, respectively (p=0.02). However, there was no statistically significant difference in the number of healthy primordial follicles between the groups one month after the last medication (p=0.33). The median atretic antral follicle counts in the first month were 2 (1-4), 3.5 (1-4), 0 (0-2), and 0 (0-0) in the control, isotretinoin, isotretinoin+COC, and isotretinoin+GnRHa groups, respectively (p=0.02). Otherwise, there were no significant differences in other types of follicles among the control and treated groups (p>0.05). There was also no statistical difference between the groups regarding immunostaining intensity for active caspase-3 evaluated in the first or second month of treatment (p=0.8 and 0.2, respectively).

CONCLUSIONS

Our results show that GnRH agonists or COC have no protective effects on ovarian reserve when co-administered with isotretinoin in the rat model.

Moderate disability has negative effect on spatiotemporal parameters in patients with chronic low back pain

BACKGROUND

It is known that the patients with chronic low back pain (CLBP) has different spatiotemporal characteristics than healthy controls such as average speed, cadence, step and stride length parameters. CLBP is a heterogeneous phenomenon in terms of causing various level of disability.

RESEARCH QUESTION

Does disability levels make a difference on spatiotemporal characteristics of patients with CLBP?

METHODS

66 patients with CLBP and 32 healthy controls between the ages of 25 and 65 years participated to study. The patients who had neurological, orthopedic, cardiovascular, metastatic history excluded from study. Resting, activity and night pain and functional disability were evaluated with Visual Analog Scale (VAS), Oswestry Disability Index (ODI) respectively. The patients were divided into two groups according to their disability level: moderate and severe. Gait analyses were performed with Optogait treadmill-based photocell system (Version 1.6.4.0, Microgate, Bolzano, Italy). After two trials were done, the spatiotemporal characteristics recorded for one minute while patients walked their preferred speed on the treadmill. One-way ANOVA was used to compare these parameters among the perceived disability level (moderate, severe) and healthy controls.The level of significance was accepted as 0.05.

RESULTS

Step length, stride length, and preferred walking speed were the parameters that differentiate the gait between healthy controls and patients with CLBP (p < 0.05). According to post-hoc analyses, moderate CLBP was identified as the group most different from the healthy controls (p < 0.05).

SIGNIFICANCE

Results of this study describe how compensating mechanism were seen in CLBP subgroups. As opposed to expectations, an increase in disability would not create higher difference in spatiotemporal characteristics between healthy controls and patients with severe disability. We propose that patients with severe and moderate disability had different ways to normalize their gait.

Effects of pioglitazone on ventricular myocyte shortening and Ca(2+) transport in the Goto-Kakizaki type 2 diabetic rat

Pioglitazone (PIO) is a thiazolidindione antidiabetic agent which improves insulin sensitivity and reduces blood glucose in experimental animals and treated patients. At the cellular level the actions of PIO in diabetic heart are poorly understood. A previous study has demonstrated shortened action potential duration and inhibition of a variety of transmembrane currents including L-type Ca(2+) current in normal canine ventricular myocytes. The effects of PIO on shortening and calcium transport in ventricular myocytes from the Goto-Kakizaki (GK) type 2 diabetic rat have been investigated. 10 min exposure to PIO (0.1-10 microM) reduced the amplitude of shortening to similar extents in ventricular myocytes from GK and control rats. 1 microM PIO reduced the amplitude of the Ca(2+) transients to similar extents in ventricular myocytes from GK and control rats. Caffeine-induced Ca(2+) release from the sarcoplasmic reticulum and recovery of Ca(2+) transients following application of caffeine and myofilament sensitivity to Ca(2+) were not significantly altered in ventricular myocytes from GK and control rats. Amplitude of L-type Ca(2+) current was not significantly decreased in myocytes from GK compared to control rats and by PIO treatment. The negative inotropic effects of PIO may be attributed to a reduction in the amplitude of the Ca(2+) transient however, the mechanisms remain to be resolved.

Calcium Signaling in the Ventricular Myocardium of the Goto-Kakizaki Type 2 Diabetic Rat

The association between diabetes mellitus (DM) and high mortality linked to cardiovascular disease (CVD) is a major concern worldwide. Clinical and preclinical studies have demonstrated a variety of diastolic and systolic dysfunctions in patients with type 2 diabetes mellitus (T2DM) with the severity of abnormalities depending on the patients' age and duration of diabetes. The cellular basis of hemodynamic dysfunction in a type 2 diabetic heart is still not well understood. The aim of this review is to evaluate our current understanding of contractile dysfunction and disturbances of Ca²⁺ transport in the Goto-Kakizaki (GK) diabetic rat heart. The GK rat is a widely used nonobese, nonhypertensive genetic model of T2DM which is characterized by insulin resistance, elevated blood glucose, alterations in blood lipid profile, and cardiac dysfunction.

The Pattern of mRNA Expression Is Changed in Sinoatrial Node from Goto-Kakizaki Type 2 Diabetic Rat Heart

BACKGROUND

In vivo experiments in Goto-Kakizaki (GK) type 2 diabetic rats have demonstrated reductions in heart rate from a young age. The expression of genes encoding more than 70 proteins that are associated with the generation and conduction of electrical activity in the GK sinoatrial node (SAN) have been evaluated to further clarify the molecular basis of the low heart rate.

MATERIALS AND METHODS

Heart rate and expression of genes were evaluated with an extracellular electrode and real-time RT-PCR, respectively. Rats aged 12-13 months were employed in these experiments.

RESULTS

Isolated spontaneous heart rate was reduced in GK heart (161 ± 12 bpm) compared to controls (229 ± 11 bpm). There were many differences in expression of mRNA, and some of these differences were of particular interest. Compared to control SAN, expression of some genes were downregulated in GK-SAN: gap junction, Gja1 (Cx43), Gja5 (Cx40), Gjc1 (Cx45), and Gjd3 (Cx31.9); cell membrane transport, Trpc1 (TRPC1) and Trpc6 (TRPC6); hyperpolarization-activated cyclic nucleotide-gated channels, Hcn1 (HCN1) and Hcn4 (HCN4); calcium channels, Cacna1d (Ca_v1.3), Cacna1g (Ca_v3.1), Cacna1h (Ca_v3.2), Cacna2d1 (Ca_vα2δ1), Cacna2d3 (Ca_vα2δ3), and Cacng4 (Cav _γ 4); and potassium channels, Kcna2 (K_v1.2), Kcna4 (K_v1.4), Kcna5 (K_v1.5), Kcnb1 (K_v2.1), Kcnd3 (K_v4.3), Kcnj2 (K_ir2.1), Kcnk1 (TWIK1), Kcnk5 (K_2P5.1), Kcnk6 (TWIK2), and Kcnn2 (SK2) whilst others were upregulated in GK-SAN: Ryr2 (RYR2) and Nppb (BNP).

CONCLUSIONS

This study provides new insight into the changing expression of genes in the sinoatrial node of diabetic heart.

Co-administration of cisplatin and curcumin does not alter mood-associated behaviors

OBJECTIVES

Cisplatin (cis-diamminedichloroplatinum (II)) is a widely-used platinum-based chemotherapeutic agent which has dose-limiting side-effects. Also, the drug resistance is another instance that decreases treatment success in cisplatin chemotherapy. The growing body of evidence suggests that curcumin, a polyphenolic compound extracted from the spice turmeric, may exert synergistic effects and sensitize malign cells to cisplatin, while alleviating cytotoxicity-related side-effects. The present study was aimed to investigate mood-associated interactions between cisplatin and curcumin.

MATERIALS AND METHODS

Thirty-four adult male Wistar albino rats were randomly assigned to four groups as control, curcumin (300 mg/kg/day, p.o. for 5 weeks), cisplatin (5 mg/kg/week, i.p. for 5 weeks), and curcumin plus cisplatin (same doses as above). The open field, elevated plus maze, and forced swim tests were engaged to evaluate mood-associated behaviors.

RESULTS

We demonstrated that depression- and anxiety-like behaviors were not altered by the administration of curcumin along with the chronic cisplatin treatment.

CONCLUSION

According to the results of the present study, we concluded that curcumin might be regarded as a safe adjuvant in cisplatin chemotherapy in terms of the mood-associated behaviors (Fig. 4, Ref. 41).

Reduction in the amplitude of shortening and Ca(2+) transient by phlorizin and quercetin-3-O-glucoside in ventricular myocytes from streptozotocin-induced diabetic rats

Diabetes mellitus is the leading cause of cardiovascular morbidity and mortality. Phlorizin (PHLOR) and quercetin-3-O-glucoside (QUER-3-G) are two natural compounds reported to have antidiabetic properties by inhibiting sodium/glucose transporters. Their effects on ventricular myocyte shortening and intracellular Ca(2+) in streptozotocin (STZ)-induced diabetic rats were investigated. Video edge detection and fluorescence photometry were used to measure ventricular myocyte shortening and intracellular Ca(2+), respectively. Blood glucose in STZ rats was 4-fold higher (469.64+/-22.23 mg/dl, n=14) than in Controls (104.06+/-3.36 mg/dl, n=16). The amplitude of shortening was reduced by PHLOR in STZ (84.76+/-2.91 %, n=20) and Control (83.72+/-2.65 %, n=23) myocytes, and by QUER-3-G in STZ (79.12+/-2.28 %, n=20) and Control (76.69+/-1.92 %, n=30) myocytes. The amplitude of intracellular Ca(2+) was also reduced by PHLOR in STZ (82.37+/-3.16 %, n=16) and Control (73.94+/-5.22 %, n=21) myocytes, and by QUER-3-G in STZ (73.62+/-5.83 %, n=18) and Control (78.32+/-3.54 %, n=41) myocytes. Myofilament sensitivity to Ca(2+) was not significantly altered by PHLOR; however, it was reduced by QUER-3-G modestly in STZ myocytes and significantly in Controls. PHLOR and QUER-3-G did not significantly alter sarcoplasmic reticulum Ca(2+) in STZ or Control myocytes. Altered mechanisms of Ca(2+) transport partly underlie PHLOR and QUER-3-G negative inotropic effects in ventricular myocytes from STZ and Control rats.

Rosuvastatin-induced responses in calf cardiac vein

OBJECTIVE

The effects of Rho-kinase inhibitors on vasodilatation induced by 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor rosuvastatin (10-9-10-4M) on 5-HT-precontracted calf cardiac vein and the role of endothelium in these effects were analyzed.

MATERIAL AND METHODS

Cardiac vein ring preparations were suspended in organ baths containing 25 ml of Krebs-Henseleit solution, maintained at 37 °C and continuously gassed with 95% O2-5% CO2. At the end of the resting period, the cardiac vein preparations were contracted with 10(-6) M 5-HT. After the contraction had reached a steady state, rosuvastatin was added to the organ bath cumulatively (10(-9)-10(-4) M).

RESULTS

Rosuvastatin relaxed the cardiac vein rings in general while the degree of relaxation was greater in those with endothelium and lower in those without it. HA1077 [1-(5-isoquinolinesulfonyl)-homopiperazine] (Fasudil, 10(-6) M) and Y-27632 [(+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexane carboxamide dihydrochloride] (10(-6) M) incubation increased the rosuvastatin-induced relaxation only in the presence of endothelium.

CONCLUSIONS

The results demonstrate for the first time that in calf cardiac vein, rosuvastatin induced endothelium-dependent relaxations while Rho-kinase inhibition increased these relaxations in the presence of endothelium layer (Fig. 3, Ref. 44).

Inhibitory actions of bisabolol on α7-nicotinic acetylcholine receptors

Bisabolol is a plant-derived monocyclic sesquiterpene alcohol with antinociceptive and antiinflammatory actions. However, molecular targets mediating these effects of bisabolol are poorly understood. In this study, using a two-electrode voltage-clamp and patch-clamp techniques and live cellular calcium imaging, we have investigated the effect of bisabolol on the function of human α7 subunit of nicotinic acetylcholine receptor (nAChR) in Xenopus oocytes, interneurons of rat hippocampal slices. We have found that bisabolol reversibly and concentration dependently (IC50 = 3.1 μM) inhibits acetylcholine (ACh)-induced α7 receptor-mediated currents. The effect of bisabolol was not dependent on the membrane potential. Bisabolol inhibition was not changed by intracellular injection of the Ca(2+) chelator BAPTA and perfusion with Ca(2+)-free solution containing Ba(2+), suggesting that endogenous Ca(2+)-dependent Cl(-) channels are not involved in bisabolol actions. Increasing the concentrations of ACh did not reverse bisabolol inhibition. Furthermore, the specific binding of [(125)I] α-bungarotoxin was not attenuated by bisabolol. Choline-induced currents in CA1 interneurons of rat hippocampal slices were also inhibited with IC50 of 4.6 μM. Collectively, our results suggest that bisabolol directly inhibits α7-nAChRs via a binding site on the receptor channel.

The comparison of preemptive analgesic effects of curcumin and diclofenac

OBJECTIVE

Preemptive analgesia is an antinociceptive treatment that prevents central sensitization. Antinociceptive effects of diclofenac are well-known. The aim of this study was to investigate preemptive analgesic effects of curcumin and diclofenac, before acute and inflammatory induced pain in rat model.

MATERIAL AND METHODS

Fourty eight old female (n = 6 in each group) Wistar Albino rats were included in the study. Paw movements in response to paw flinching in response to formalin injection or thermal stimulation were compared after curcumin (400 mg kg-(1), p.o.) and diclofenac (10 mg kg(-1), i.p.) administration. Saline was used as a control. The solvent ethanol was administered in another group of rats. Preemptive analgesic effect was significant in both tests when curcumin and diclofenac was administrated before the pain stimuli.

RESULTS

Oral administration of curcumin and intraperitoneal injection of diclofenac increase the response time in hot plate test and decrease the number of flinches in formalin test (p < 0.001 vs p < 0.05).

CONCLUSION

These results suggest that curcumin had preemptive analgesic effects on acute thermal, and inflammatory induced pain in rats as diclofenac (Fig. 2, Ref. 35).

Is lateral localisation of placenta a risk factor for adverse perinatal outcomes?

The aim of this study was to evaluate the relationship between placental localisation and perinatal outcomes. This study was performed in a tertiary centre hospital by retrospectively analysing the medical records of patients who were followed up and underwent delivery in the same hospital. The patients were divided into two groups according to the placental locations (central and lateral) in their routine sonographic findings between the 18 and 24 weeks' gestation. Out of 1,057 patients, 87.4% (n = 919) had centrally located placentas and 12.6% (n = 133) had laterally located placentas. Preeclampsia was found to be significantly higher in the lateral placental location group (4.5% vs. 1.6%; p = 0.027). There was a significant correlation with foetal growth restriction (FGR), preterm birth rates, low Apgar scores and need for neonatal intensive care unit in the lateral placental location group (p < 0.05). The pregnant women with laterally located placentas should be followed up promptly with special care for the risk of preeclampsia and FGR, and poor neonatal outcomes.

Effects of exercise preconditioning on intestinal ischemia-reperfusion injury

BACKGROUND

To investigate the effects of exercise preconditioning on oxidative injury in the intestinal tissue of rats.

METHODS

Sixty male Wistar rats were randomly divided into six groups as sham (n = 10), ischemia-reperfusion (n = 10), exercise (n = 10), exercise plus ischemia-reperfusion (n = 10), ischemic preconditioning (n = 10), and ischemic preconditioning plus ischemia-reperfusion groups (n = 10). Tissue levels of malondialdehyde and activities of myeloperoxidase and superoxide dismutase, and serum levels of tumor necrosis factor-alpha and interleukin-6 were measured. Intestinal tissue histopathology was also evaluated by light microscopy.

RESULTS

Tumor necrosis factor-alpha concentrations significantly decreased in the exercise group compared to the sham group (p < 0.05). Myeloperoxidase activity significantly increased and superoxide dismutase activity significantly decreased in ischemia-reperfusion group compared to the sham group (p < 0.05). Superoxide dismutase activity in the ischemic preconditioning and ischemic preconditioning plus ischemia-reperfusion groups were significantly higher compared to the ischemia-reperfusion and exercise groups (p < 0.05). Histopathologically, intestinal injury significantly attenuated in the exercise plus ischemia-reperfusion group compared to the ischemia-reperfusion group.

CONCLUSIONS

The results of the present study indicate that exercise training seems to have a protective role against intestinal ischemia-reperfusion injury (Tab. 3, Fig. 1, Ref. 35).

Effects of a sucrose-enriched diet on the pattern of gene expression, contraction and Ca(2+) transport in Goto-Kakizaki type 2 diabetic rat heart

There has been a spectacular rise in the global prevalence of type 2 diabetes mellitus (T2DM), and cardiovascular disease is the major cause of morbidity and mortality in diabetic patients. A variety of diastolic and systolic dysfunctions have been demonstrated in type 2 diabetic heart. The consumption of sugar-sweetened beverages has been linked to rising rates of obesity, which in turn is a risk factor for development of T2DM. In this study, the effects of a sucrose-enriched diet on the pattern of gene expression, contraction and Ca(2+) transport in the Goto-Kakizaki T2DM rat heart were investigated. Genes encoding cardiac muscle proteins (Myh7, Mybpc3, Myl1, Myl3 and Mylpf), intercellular proteins (Gja4), cell membrane transport (Atp1b1), calcium channels (Cacna1c, Cacna1g and Cacnb1) and potassium channels (Kcnj11) were upregulated and genes encoding potassium channels (Kcnb1) were downregulated in GK compared with control rats. Genes encoding cardiac muscle proteins (Myh6, Mybpc3 and Tnn2), intercellular proteins (Gja1 and Gja4), intracellular Ca(2+) transport (Atp2a1 and Ryr2), cell membrane transport (Atp1a2 and Atp1b1) and potassium channel proteins (Kcnj2 and Kcnj8) were upregulated and genes encoding cardiac muscle proteins (Myh7) were downregulated in control rats fed sucrose compared with control rats. Genes encoding cardiac muscle proteins (Myh7) and potassium channel proteins (Kcnj11) were downregulated in control and GK rats fed sucrose compared with control and GK rats, respectively. The amplitude of shortening was reduced in myocytes from the control-sucrose group compared with control rats and in the GK-sucrose group compared with GK rats. The amplitude of the Ca(2+) transient was increased in myocytes from control-sucrose compared with control rats and decreased in GK-sucrose compared with GK rats. Subtle alterations in the pattern of expression of genes encoding a variety of cardiac muscle proteins are associated with changes in shortening and intracellular Ca(2+) transport in ventricular myocytes from GK T2DM and control rats fed a sucrose-enriched diet.

Involvement of the α7-nicotinic acetylcholine receptors in the anti-inflammatory action of the thymulin-related peptide (PAT)

BACKGROUND AND PURPOSE

Peptide analog of thymulin (PAT) has been shown to have anti-hyperalgesic and anti-inflammatory properties in animal models of inflammation. Recent reports suggest that the peripheral cholinergic system has an anti-inflammatory role mediated by α7-nicotinic acetylcholine receptor (α7-nAChR). Our aim is to investigate whether the action of PAT is mediated, via the cholinergic pathway.

EXPERIMENTAL APPROACH

The anti-hyperalgesic and anti-inflammatory action of PAT was assessed in rat models of inflammatory nociceptive hyperactivity (carrageenan and endotoxin) and in a mice air-pouch model for localized inflammation, respectively; the possible attenuation of PAT's effects by pretreatment with the α7-nAchR specific antagonist methyllycaconitine citrate (MLA) was also investigated. In another series of experiments, using two electrode recordings, the effect of PAT on the α7-nAChRs, expressed in Xenopus Oocytes, was also determined.

KEY RESULTS

Administration of PAT reversed inflammatory nociceptive hyperactivity and cold and tactile hyperactivity in rats. This effect was partially or totally prevented by MLA, as assessed by different behavioral pain tests. Treatment with PAT also reduced the alteration of cytokines and NGF levels by carrageenan injection in the mouse air pouch model; this effect was partially antagonized by MLA. Electrophysiological recording demonstrated that PAT significantly potentiated the α7-nAchR expressed in Xenopus Oocytes. These effects were not observed when a control peptide, with a reverse sequence (rPAT), was utilized.

CONCLUSIONS AND IMPLICATIONS

The behavioral and electrophysiological observations described in this report demonstrate that PAT mediates, at least partially, its anti-inflammatory action by potentiating the α7-nAChR. These results indicate that PAT has a potential for new therapeutic applications as anti-inflammatory and analgesic agent.

Protective effects of curcumin supplementation on intestinal ischemia reperfusion injury

The aim of this study was to investigate the effects curcumin on inflammation and oxidative stress markers in the intestinal ischemia reperfusion (IIR) injury induced rats. Rats were divided into four groups: sham (S), intestinal IR (IIR), curcumin plus sham (CS), and curcumin plus intestinal IR (CIIR). Curcumin was given 200 mg kg⁻¹ for 20 days. IIR was produced by 45 min of intestinal ischemia followed by a 120 min of reperfusion. Although interleukin-6 levels tended to increase in IIR group tumor necrosis factor-α levels were not different. Intestinal myeloperoxidase activity in CS group was lower than IIR group. In intestine and heart tissues, malondialdehyde levels in CS and CIIR groups were lower than S and IIR groups. Superoxide dismutase activity in CIIR group was higher than IIR group in intestine and lung tissues. Curcumin has a protective role against ischemia reperfusion injury.

Effects of exercise training on excitation-contraction coupling and related mRNA expression in hearts of Goto-Kakizaki type 2 diabetic rats

Although, several novel forms of intervention aiming at newly identified therapeutic targets are currently being developed for diabetes mellitus (DM), it is well established that physical exercise continues to be one of the most valuable forms of non-pharmacological therapy. The aim of the study was to investigate the effects of exercise training on excitation-contraction coupling and related gene expression in the Goto-Kakizaki (GK) type 2 diabetic rat heart and whether exercise is able to reverse diabetes-induced changes in excitation-contraction coupling and gene expression. Experiments were performed in GK and control rats aged 10-11 months following 2-3 months of treadmill exercise training. Shortening, [Ca(2+)]i and L-type Ca(2+) current were measured in ventricular myocytes with video edge detection, fluorescence photometry and whole cell patch clamp techniques, respectively. Expression of mRNA was assessed in ventricular muscle with real-time RT-PCR. Amplitude of shortening, Ca(2+) transients and L-type Ca(2+) current were not significantly altered in ventricular myocytes from GK sedentary compared to control sedentary rats or by exercise training. Expression of mRNA encoding Tpm2, Gja4, Atp1b1, Cacna1g, Cacnb2, Hcn2, Kcna3 and Kcne1 were up-regulated and Gja1, Kcnj2 and Kcnk3 were down-regulated in hearts of sedentary GK rats compared to sedentary controls. Gja1, Cav3 and Kcnk3 were up-regulated and Hcn2 was down-regulated in hearts of exercise trained GK compared to sedentary GK controls. Ventricular myocyte shortening and Ca(2+) transport were generally well preserved despite alterations in the profile of expression of mRNA encoding a variety of cardiac muscle proteins in the adult exercise trained GK diabetic rat heart.

Role of curcumin in mesenteric ischemia - reperfusion injury in rats

BACKGROUND

Curcumin is an antioxidant molecule that has been shown to attenuate ischemia/reperfusion (I/R) injury in several organ systems. In the present study, we aimed to evaluate the possible effects of curcumin on contractile response to agonists and histopathological alterations in rat esophagus subjected to mesenteric I/R.

MATERIALS AND METHODS

Adult male Wistar albino rats were randomly allocated to 4 groups, namely group I: sham-operated animals (n=10); group II: animals subdued to I/R injury only (n=10) and laparotomy; 45 minutes of superior mesenteric artery ligation were followed by 2 hours of reperfusion, group III: curcumin/sham (n=10); 20 days before I/R, curcumin (200 mg/kg/) was administered by gastric gavage, and group IV: curcumin-I/R (n=10). Mesenteric ischemia/reperfusion model was generated by clamping the superior mesenteric artery for 45 min followed by reperfusion for 2 h. Oral administration of curcumin by gavage at a dose of 200 mg/kg/day lasted 20 days just before inducing the mesenteric ischemia. At the end of reperfusion period, all animals were sacrificed and esophagus samples were collected to assess the contractile response to agonists and histopathological alterations.

RESULTS

Ischemia/reperfusion significantly decreased the contractile responses to carbachol and KCl and this decrease was attenuated by curcumin. Pretreatment with curcumin caused a remarkable decrease in histopathological parameters such as edema, congestion and inflammatory cells.

CONCLUSIONS

The results of the present study demonstrate for the first time that curcumin can attenuate the esophageal injury associated with I/R (Tab. 4, Fig. 3, Ref. 32).

The role of nitric oxide on the responses of curcumin-treated rat aorta

OBJECTIVES

The aim of the present study was to evaluate the influence of endothelial nitric oxide (NO) on the vascular responses of curcumin-treated rats.

METHODS

The experimental groups included the control and curcumin-treated (200 mg/kg/day, p.o., for 4 weeks) group. The concentration response curves to receptor-dependent agent 5-hydroxytryptamine (5-HT; 10--3x10- M) and receptor-independent agent potassium chloride (KCl; 5-100 mM) were observed.

RESULTS

The concentration response curves to 5-HT and KCl shifted to the right and the maximal response was significantly decreased in the curcumin-treated rat aortas. A pretreatment of rings with L-NAME (a NOS inhibitor, 10- M) increased both the sensitivity and maximal response to only 5-HT. No apparent histological changes were demonstrated in smooth muscle and connective tissue layers in the aortas of the control and curcumin-treated rat preparations.

CONCLUSION

The results of the present study suggest that NO release from endothelial cells modulates curcumin-treated rat aorta responses to 5-HT, but not to KCl (Tab. 2, Fig. 4, Ref. 25).

Shortening and intracellular Ca2+ in ventricular myocytes and expression of genes encoding cardiac muscle proteins in early onset type 2 diabetic Goto-Kakizaki rats

There has been a spectacular rise in the global prevalence of type 2 diabetes mellitus. Cardiovascular complications are the major cause of morbidity and mortality in diabetic patients. Contractile dysfunction, associated with disturbances in excitation-contraction coupling, has been widely demonstrated in the diabetic heart. The aim of this study was to investigate the pattern of cardiac muscle genes that are involved in the process of excitation-contraction coupling in the hearts of early onset (8-10 weeks of age) type 2 diabetic Goto-Kakizaki (GK) rats. Gene expression was assessed in ventricular muscle with real-time RT-PCR; shortening and intracellular Ca(2+) were measured in ventricular myocytes with video edge detection and fluorescence photometry, respectively. The general characteristics of the GK rats included elevated fasting and non-fasting blood glucose and blood glucose at 120 min following a glucose challenge. Expression of genes encoding cardiac muscle proteins (Myh6/7, Mybpc3, Myl1/3, Actc1, Tnni3, Tnn2, Tpm1/2/4 and Dbi) and intercellular proteins (Gja1/4/5/7, Dsp and Cav1/3) were unaltered in GK ventricle compared with control ventricle. The expression of genes encoding some membrane pumps and exchange proteins was unaltered (Atp1a1/2, Atp1b1 and Slc8a1), whilst others were either upregulated (Atp1a3, relative expression 2.61 ± 0.69 versus 0.84 ± 0.23) or downregulated (Slc9a1, 0.62 ± 0.07 versus 1.08 ± 0.08) in GK ventricle compared with control ventricle. The expression of genes encoding some calcium (Cacna1c/1g, Cacna2d1/2d2 and Cacnb1/b2), sodium (Scn5a) and potassium channels (Kcna3/5, Kcnj3/5/8/11/12, Kchip2, Kcnab1, Kcnb1, Kcnd1/2/3, Kcne1/4, Kcnq1, Kcng2, Kcnh2, Kcnk3 and Kcnn2) were unaltered, whilst others were either upregulated (Cacna1h, 0.95 ± 0.16 versus 0.47 ± 0.09; Scn1b, 1.84 ± 0.16 versus 1.11 ± 0.11; and Hcn2, 1.55 ± 0.15 versus 1.03 ± 0.08) or downregulated (Hcn4, 0.16 ± 0.03 versus 0.37 ± 0.08; Kcna2, 0.35 ± 0.03 versus 0.80 ± 0.11; Kcna4, 0.79 ± 0.25 versus 1.90 ± 0.26; and Kcnj2, 0.52 ± 0.07 versus 0.78 ± 0.08) in GK ventricle compared with control ventricle. The amplitude of ventricular myocyte shortening and the intracellular Ca(2+) transient were unaltered; however, the time-to-peak shortening was prolonged and time-to-half decay of the Ca(2+) transient was shortened in GK myocytes compared with control myocytes. The results of this study demonstrate changes in expression of genes encoding various excitation-contraction coupling proteins that are associated with disturbances in myocyte shortening and intracellular Ca(2+) transport.

Contractility of ventricular myocytes is well preserved despite altered mechanisms of Ca2+ transport and a changing pattern of mRNA in aged type 2 Zucker diabetic fatty rat heart

There has been a spectacular rise in the global prevalence of type 2 diabetes mellitus and cardiovascular complications are the major cause of morbidity and mortality in diabetic patients. The objective of the study was to investigate ventricular myocyte shortening, intracellular Ca(2+) signalling and expression of genes encoding cardiac muscle proteins in the aged Zucker diabetic fatty (ZDF) rat. There was a fourfold elevation in non-fasting blood glucose in ZDF rats (478.43 ± 29.22 mg/dl) compared to controls (108.22 ± 2.52 mg/dl). Amplitude of shortening, time to peak (TPK) and time to half (THALF) relaxation of shortening were unaltered in ZDF myocytes compared to age-matched controls. Amplitude and THALF decay of the Ca(2+) transient were unaltered; however, TPK Ca(2+) transient was prolonged in ZDF myocytes (70.0 ± 3.2 ms) compared to controls (58.4 ± 2.3 ms). Amplitude of the L-type Ca(2+) current was reduced across a wide range of test potentials (-30 to +40 mV) in ZDF myocytes compared to controls. Sarcoplasmic reticulum Ca(2+) content was unaltered in ZDF myocytes compared to controls. Expression of genes encoding cardiac muscle proteins, membrane Ca(2+) channels, and cell membrane ion transport and intracellular Ca(2+) transport proteins were variously altered. Myh6, Tnnt2, Cacna2d3, Slc9a1, and Atp2a2 were downregulated while Myl2, Cacna1g, Cacna1h, and Atp2a1 were upregulated in ZDF ventricle compared to controls. The results of this study have demonstrated that preserved ventricular myocyte shortening is associated with altered mechanisms of Ca(2+) transport and a changing pattern of genes encoding a variety of Ca(2+) signalling and cardiac muscle proteins in aged ZDF rat.

Analysis of lung metastases in patients with primary extremity sarcoma

Purpose: To investigate the incidence, radiographic findings, and the time course for the appearence of lung metastases from primary extremity sarcoma.

Patients and methods: Four-hundred patients with extremity sarcoma were evaluated retrospectively for lung metastases. Multiple clinical factors were analyzed for possible influence on the metastases-free interval and subsequent metastases development. Radiographic findings of metastases were also reviewed.

Results: Ninety of 400 patients (23%) developed lung metastases. Median time from presentation to detection of metastasis was 8.0 ± 1.1 months (95% CI: 6.02–9.98). More than 75% of patients developed metastases within 1 year after presentation of the primary sarcoma. As disease grade increased, the metastases-free intervals shortened significantly. Histologically, synoviosarcoma and osteogenic sarcoma were more often associated with the development of lung metastases. In this subgroup, 54 patients (60%), the presence of solitary (11) or multiple (43) nodular metastases was the only radiological finding. In 36 of 90 patients (40%), parenchymal mass, pleural effusion, hilar lymphadenopathy and pneumothorax were found.

Conclusions: Twenty-three percent of patients in our study developed lung metastases. As the grade of the disease increased, metastases-free intervals are shortened. Although it has been reported that lung metastases in patients with extremity sarcomas may present as solitary or multiple nodules in earlier trials with radiographic screening methods, the current review of 400 patients found that a substantial number of patients may present radiological appearances other than nodular formations.

Oxime reactivators and their in vivo and in vitro effects on nicotinic receptors

Current treatment of organophosphorus poisoning, resulting in overstimulation and desensitization of muscarinic and nicotinic receptors by acetylcholine (ACh), consists of the administration of atropine and oxime reactivators. However, no versatile oxime reactivator has been developed yet and some mortality still remains after application of standard atropine treatment, probably due to its lack of antinicotinic action. In our study, we focused on the interesting non-acetylcholinesterase property of oximes, i.e. antinicotinic effect of reactivators. Two standard reactivators (HI-6, obidoxime) and two new compounds (K027 and K203) were chosen for in vitro (patch clamp) and in vivo (nerve-evoked muscle contraction) testings. Both examinations showed antinicotinic effects of the reactivators. In vitro inhibition of acetylcholine-evoked currents by obidoxime, HI-6 and K203 was equivalent while K027 was less potent. Similar order of potency was observed by the in vivo examinations. We thus confirm previous in vitro results, which describe antinicotinic effects of oxime reactivators, and furthermore, we show in vivo antagonism of oxime reactivators exerted by the inhibition of ACh effect on the nicotinic receptor in the neuromuscular junction. Taking together, the effects of tested oxime reactivators indicate an antagonism on both embryonic and adult form of the muscle nicotinic receptors.

Changing pattern of gene expression is associated with ventricular myocyte dysfunction and altered mechanisms of Ca2+ signalling in young type 2 Zucker diabetic fatty rat heart

The association between type 2 diabetes and obesity is very strong, and cardiovascular complications are the major cause of morbidity and mortality in diabetic patients. The aim of this study was to investigate early changes in the pattern of genes encoding cardiac muscle regulatory proteins and associated changes in ventricular myocyte contraction and Ca(2+) transport in young (9- to 13-week-old) type 2 Zucker diabetic fatty (ZDF) rats. The amplitude of myocyte shortening was unaltered; however, time-to-peak shortening and time to half-relaxation of shortening were prolonged in ZDF myocytes (163 ± 5 and 127 ± 7 ms, respectively) compared with age-matched control rats (136 ± 5 and 103 ± 4 ms, respectively). The amplitude of the Ca(2+) transient was unaltered; however, time-to-peak Ca(2+) transient was prolonged in ZDF myocytes (66.9 ± 2.6 ms) compared with control myocytes (57.6 ± 2.3 ms). The L-type Ca(2+) current was reduced, and inactivation was prolonged over a range of test potentials in ZDF myocytes. At 0 mV, the density of L-type Ca(2+) current was 1.19 ± 0.28 pA pF(-1) in ZDF myocytes compared with 2.42 ± 0.40 pA pF(-1) in control myocytes. Sarcoplasmic reticulum Ca(2+) content, release and uptake and myofilament sensitivity to Ca(2+) were unaltered in ZDF myocytes compared with control myocytes. Expression of genes encoding various L-type Ca(2+) channel proteins (Cacna1c, Cacna1g, Cacna1h and Cacna2d1) and cardiac muscle proteins (Myh7) were upregulated, and genes encoding intracellular Ca(2+) transport regulatory proteins (Atp2a2 and Calm1) and some cardiac muscle proteins (Myh6, Myl2, Actc1, Tnni3, Tnn2, and Tnnc1) were downregulated in ZDF heart compared with control heart. A change in the expression of genes encoding myosin heavy chain and L-type Ca(2+) channel proteins might partly underlie alterations in the time course of contraction and Ca(2+) transients in ventricular myocytes from ZDF rats.

Vasoprotection by melatonin and quercetin in rats treated with cisplatin

Cisplatin-based chemotherapy has a variety of vascular side effects. The aim of the present study was to evaluate the beneficial effect of melatonin and cisplatin on the alterations in vascular reactivity and structure of cisplatin-treated rats. Phenylephrine (PHE) and KCl-caused concentration-dependent contractions of rat aorta. Pretreatment with cisplatin increased the sensitivity but not the max response to PHE and KCl. In rats treated with melatonin or quercetin before cisplatin, the EC50 values, but not the maximal response to both agents were significantly higher than cisplatin-treated group. Compared to the control group, cisplatin-treatment significantly reduced the luminal area of the aorta. In melatonin and quercetin-treated aortas the luminal area values were significantly higher than cisplatin-treated group. The results demonstrate for the first time that melatonin and quercetin treatment may protect the aorta in cisplatin-based chemotherapy.

The effect of Δ9-tetrahydrocannabinol on 5-HT3 receptors depends on the current density

The effects of Δ(9)-tetrahydrocannabinol (THC), the psychoactive component of cannabis, on the function of 5-HT type 3 (5-HT(3)) receptors were investigated using a two-electrode voltage clamp technique in Xenopus oocytes, and a whole-cell patch clamp technique in rat nodose ganglion neurons. In oocytes injected with 3 ng cRNA of 5-HT(3A) receptor, THC reversibly inhibited currents evoked with 5-HT (1 μM) in a concentration-dependent manner (IC(50)=1.2 μM). The extent of THC inhibition was inversely correlated with the amount of cRNA injected and the mean 5-HT(3A) receptor current densities. Pretreatment with actinomycin D, which inhibits transcription, decreased the mean 5-HT(3) receptor current density and increased the extent of THC inhibition on 5-HT(3) receptor-mediated currents. The IC(50) values for THC increased from 285 nM to 1.2 μM in oocytes injected with 1 and 3 ng of 5-HT(3A) cRNA, respectively. In radioligand binding studies on membrane preparations of oocytes expressing 5-HT(3A) receptors, THC did not alter the specific binding of a 5-HT(3A) receptor antagonist, [(3)H]GR65630. In the presence of 1 μM THC, the maximum 5-HT-induced response was also inhibited without a significant change in 5-HT potency, indicating that THC acts as a noncompetitive antagonist on 5-HT(3) receptors. In adult rat nodose ganglion neurons, application of 1 μM THC caused a significant inhibition of 5-HT(3) receptors, extent of which correlated with the density of 5-HT-induced currents, indicating that the observed THC effects occur in mammalian neurons. The inhibition of 5-HT(3) receptors by THC may contribute to its pharmacological actions in nociception and emesis.

[Temporary intramedullary stabilisation of infected non-union in long bones with local antibiotic-impregnated cement rods: case reports]

BACKGROUND

The therapy for infected non-union is complicated and needs multidisciplinary action. The fixateur externe is usually used to stabilise an osteosynthesis temporarily or permanently. But it shows a high risk with adipose patients and when the bone is already damaged. That is why alternative modes of action have been looked for. For temporary stabilisation and simultaneous antibiotic therapy we have invented and now use a custom-made cement rod impregnated with antibiotics.

METHOD

We use a plastic high-lumen thorax drainage tube which is filled with cement mixed with antibiotics and a K-wire. When the cement has set the plastic is removed. The cement rod acts as a space holder. After the infection has calmed down we remove the space holder and a definitive stabilisation with a titanium nail is performed.

RESULTS

The active substance levels tested in the wound exudation showed results clearly above the minimum inhibitory concentration. Early mobilisation with sole contact was mainly possible.The wound dressing could be performed without problems and an additional stabilisation was not necessary. Clinically the infection calmed down after 3 to 4 weeks.

DISCUSSION

The therapy for infected non-union of tubular bones consists of the complete removal of metal, the resection of the pseudarthrosis, the filling of the defect and the re-osteosynthesis. Intramedullary space holders offer a biomechanical stabilization as an intramedullary carrier of weight with additional simultaneous antibiotic therapy.

CONCLUSION

The use of an intramedullary spaceholder made of antibiotic-impregnated cement in infected non-unions avoids the specific complications of a fixateur externe and is definitely more comfortable for the patient. Locally high antibiotic levels are reached, the treatment takes less time.

[Effects of N-stearoyl- and N-oleoylethanolamine on cardiac voltage-dependent sodium channels]

The group of N-acylethanolamines (NAE) includes lipids that are capable of modulating plasma membrane ion channels without involvement of cannabinoid receptors. However, the action of various members of NAE on voltage-gated Na+ channels (VGSC) in cardiac tissue is still not fully elucidated. Here using patch-clamp technique we have studied the modulation of biophysical properties of VGSC of neonatal cardiomyocytes by saturated N-stearoylethanolamine (NSE) and monounsaturated N-oleoylethanolamine (OEA). NSE in 1-200 tM concentration range did not significantly alter the amplitude of inward Na+ current (I(Na)), but 100 microM NSE shifted its steady-state activation and inactivation curves in hyperpolarization direction by 2.4 mV and 10.6 mV, respectively. Activation kinetics of the current was not changed by NSE, but its inactivation was accelerated by about 1.2-fold in the -60 - -30 mV range of membrane potentials. Unlike NSE, OEA dose-dependently inhibited I(Na) with kappa(D) = 11.4 +/- 1.6 microM and maximal block at saturating concentration of 30 +/- 3%. It also stronger than NSE shifted current's steady-state activation and inactivation curves (-6.4 mV and -14.0 mV, respectively, at 100 microM) in hyperpolarization direction. The effect of OEA on I(Na) activation kinetics was negligible, but it more pronouncedly than NSE accelerated inactivation of the current. Thus, both members of NAE influence the voltage-dependence of activation, inactivation and kinetics of I(Na). These effects were more prominent for monounsaturated OEA, which also partially blocked I(Na). The discovered effects of NSE and OEA on VGSCs may in part be responsible for the decrease of cardiomycytes' excitability by these lipids under normal as well as pathologic conditions.

The effects of chronic administration of sumatriptan and dipyrone on serotonergic system in the rat brain: an immunohistochemical study

OBJECTIVE

To investigate the effects of chronic high dose sumatriptan and dipyrone treatment on central serotonergic system in rats.

MATERIALS AND METHODS

Male Sprague-Dawley rats (seven per group) were daily injected with sumatriptan (3 mg/kg), dipyrone (400 mg/kg) or saline for 30 days. The brains of animals were surgically removed and immunohistochemically stained for serotonin. Serotonin-positive stained cells were counted automatically by using a computerized image analysis program. Statistical analysis carried out using one-way ANOVA followed by post hoc Tukey test.

RESULTS

A significant decrease in serotonin-positive cells in the brainstem was observed after chronic sumatriptan administration while chronic use of dipyrone induced a significant increase in serotonin-positive cells both in the cortex and midbrain.

CONCLUSION

Our data suggest that central serotonergic system might be modified by chronic use of sumatriptan and dipyrone.

[Regulation of the excitability of neonatal cardiomyocytes by N-stearoyl- and N-oleoyl-ethanolamines]

N-acylethanolamines (NAE) are biologically active lipids able of modulating ion transport through the cellular plasma membrane, however specific targets of their action and signalling mechanisms involved in cardiac tissue are still poorly understood. Physiological activity of NAEs is known to depend on the level of unsaturation. Therefore, here we investigated the effects of saturated N-stearylethanolamine (NSE) and monounsaturated N-oleylethanolamine on electric excitability of neonatal rat cardiomyocytes. 1 microM of either NSE or OEA decreased the duration of cardiac action potential (AP) from all parts of heart muscle. Shortening of AP was partially reversible, though the reversibility of AP duration upon washout of substances was more complete for endocardial ventricular compared to epicardial and atrial cardiomyocytes. I microM NSE depolarized resting membrane potential (RMP) of epicardial and of 65% of endocardial cells, whilst other cells types showed weakly reversible hyperpolarization. 1 microM OEA caused reversible RMP hyperpolarization of all studied cell types. NSE and OEA decreased the amplitude and upstroke velocity of AP that suggests their effect on sodium channels. NSE and to a lesser extent OEA inhibited the amplitude of AP phase 2 (plateau) which may indicate an inhibition of high-voltage-activated calcium channels. Effects of NSE and OEA on RMP and repolarization phase of AP (phase 3) depended on cardiac cell type suggesting differential regulation of inward rectifier Kir and voltage-gated delayed rectifier potassium channels by these lipids. We cannot also exclude interaction of NSE and OEA with anion channels, backgound K+ channels and ion transporters of the cardiomyocytes' plasma membrane. Overall, NSE-induced changes of AP parameters were less reversible than those induced by OEA, suggesting a slower degradation/ convertion of NSE in plasma membrane compared to OEA.

Decreased osteocalcin levels in patients with chronic obstructive pulmonary disease using long-term inhaled beclomethasone dipropionate

Inhaled corticosteroids have been used in the treatment of chronic obstructive pulmonary disease (COPD) for many years. However the adverse effects of corticosteroids on bone formation may require special consideration in these patients. This study was undertaken to investigate the effects of long-term inhaled beclomethasone dipropionate treatment on the biochemical markers of bone formation. For this purpose, serum osteocalcin, alkaline phosphatase, free calcium, and inorganic phosphate levels were measured in 65 male COPD patients. Patients in the control group (n = 30) had not taken oral or inhaled corticosteroids for at least 1 year. Only those patients using beclomethasone with metered-dose inhalers were included in the treatment group (n = 35). The mean age of the control group was 61.63 +/- 1.84 (mean +/- SEM). In the treatment group, the mean age was 59.10 +/- 2.29 and patients in this group had taken beclomethasone for an average time of 23.94 +/- 2.72 months (for at least 12 months) at an average concentration of 1,142.0 +/- 79.64 microg/d. The mean serum osteocalcin levels in the control group and treatment group were 7.03 +/- 0.19 ng/mL and 3.74 +/- 0.12 ng/mL, respectively. Comparison of values between groups indicates that serum osteocalcin levels in patients using beclomethasone were significantly lower than that of patients in the control group. Serum alkaline phosphatase levels were 167.96 +/- 1.49 U/L and 168.17 +/- 1.60 U/L for the control and treatment groups, respectively. There was no statistically significant difference among these values (Student's t test; P >.05). The mean values of total serum calcium and inorganic phosphate were not statistically different between the groups (P >.05). These results indicate that long-term inhaled beclomethasone treatment in COPD patients may induce significant changes in osteocalcin levels and require close monitoring for osteoporotic changes.

Electrophysiological evidence for vasopressin V(1) receptors on neonatal motoneurons, premotor and other ventral horn neurons

Prominent arginine-vasopressin (AVP) binding and AVP V(1) type receptors are expressed early in the developing rat spinal cord. We sought to characterize their influence on neural excitability by using patch-clamp techniques to record AVP-induced responses from a population of motoneurons and interneurons in neonatal (5-18 days) rat spinal cord slices. Data were obtained from 58 thoracolumbar (T(7)-L(5)) motoneurons and 166 local interneurons. A majority (>90%) of neurons responded to bath applied AVP (10 nM to 3 microM) and (Phe(2), Orn(8))-vasotocin, a V(1) receptor agonist, but not V(2) or oxytocin receptor agonists. In voltage-clamp, postsynaptic responses in motoneurons were characterized by slowly rising, prolonged (7-10 min) and tetrodotoxin-resistant inward currents associated with a 25% reduction in a membrane potassium conductance that reversed near -100 mV. In interneurons, net AVP-induced inward currents displayed three patterns: decreasing membrane conductance with reversal near -100 mV, i.e., similar to that in motoneurons (24 cells); increasing conductance with reversal near -40 mV (21 cells); small reduction in conductance with no reversal within the current range tested (41 cells). A presynaptic component recorded in most neurons was evident as an increase in the frequency but not amplitude (in motoneurons) of inhibitory and excitatory postsynaptic currents (IPSCs and EPSCs), in large part due to AVP-induced firing in inhibitory (mainly glycinergic) and excitatory (glutamatergic) neurons synapsing on the recorded cells. An increase in frequency but not amplitude of miniature IPSCs and EPSCs also indicated an AVP enhancement of neurotransmitter release from axon terminals of inhibitory and excitatory interneurons. These observations provide support for a broad presynaptic and postsynaptic distribution of AVP V(1) type receptors and indicate that their activation can enhance the excitability of a majority of neurons in neonatal ventral spinal cord.

Direct inhibition of voltage-dependent Ca(2+) fluxes by ethanol and higher alcohols in rabbit T-tubule membranes

The effects of ethanol and higher alcohols on 45Ca(2+) fluxes, mediated by voltage-dependent Ca(2+) channels (VDCCs), were investigated in inside-out transverse (T)-tubule membrane vesicles from rabbit skeletal muscle. 45Ca(2+) effluxes were induced by membrane potentials generated via establishing K(+) gradients across the vesicles, and were significantly inhibited by the inorganic Ca(2+) channel blocker La(3+) (1 mM) and the Ca(2+) channel antagonist nifedipine (1-10 microM). Ethanol, in the concentration range of 100-400 mM, caused a significant suppression of depolarization-induced 45Ca(2+) fluxes. Ethanol also functionally modulated the effect of nifedipine (1-10 microM) and the Ca(2+) channel agonist Bay K 8644 (1 microM) on Ca(2+) effluxes. Pretreatment with pertussis toxin (5 microg/ml) or phorbol 12-myrstate 13-acetate (PMA, 50 nM) did not affect the ethanol inhibition of 45Ca(2+) fluxes. Further experiments with alcohols revealed that butanol, hexanol, octanol and decanol also significantly inhibited 45Ca(2+) effluxes. However, undecanol and dodecanol did not cause any significant change on 45Ca(2+) fluxes, indicating that the effects of alcohols on 45Ca(2+) effluxes exhibit a cut-off phenomenon. In radioligand binding studies, it was found that at the concentrations used in flux studies, alcohols did not alter the characteristics of the specific binding of [3H]PN 200-110 to T-tubule membranes. Results indicate that ethanol directly inhibits the function of voltage-dependent Ca(2+) channels without modulating the specific binding of Ca(2+) channel ligands of the dihydropyridine class, and that this inhibition is independent of intracellular Ca(2+) levels.

Cardiac assist devices for end-stage heart failure

Cardiac assist devices have become an important therapy for patients with end-stage cardiac failure. These devices continue to evolve. Most current devices provide temporary, left-sided support for patients with cardiogenic shock from postcardiotomy syndrome or for patients awaiting cardiac transplantation. The two most frequently used left ventricular assist devices as a bridge to transplant are the Thermocardiosystems (HeartMate I) and the Novacor devices. The selection criteria for the use of these devices and treatment of these patients will be reviewed. Additionally, other currently available devices and future devices are also presented and discussed.

Endogenous cannabinoid anandamide directly inhibits voltage-dependent Ca(2+) fluxes in rabbit T-tubule membranes

The effect of the endogenous cannabinoid, anandamide on Ca(2+) flux responses mediated by voltage-dependent Ca(2+) channels was studied in transverse tubule membrane vesicles from rabbit skeletal muscle. Vesicles were loaded with 45Ca(2+) and membrane potentials were generated by establishing K(+) gradients across the vesicle using the ionophore, valinomycin. Anandamide, in the range of 1-100 microM, inhibited depolarization-induced efflux responses. Anandamide also functionally modulated the effects of nifedipine (1-10 microM) and Bay K 8644 (1 microM) on Ca(2+) flux responses. Pretreatment with the specific cannabinoid receptor antagonist, SR141716A (1 microM), pertussis toxin (5 microg/ml), the amidohydrolase inhibitor, phenylmethylsulfonyl fluoride (0.2 mM) or the cyclooxygenase inhibitor, indomethacin (5 microM) did not alter the inhibition of efflux responses by anandamide. Arachidonic acid (10-100 microM) also effectively inhibited 45Ca(2+) efflux from membrane vesicles. In radioligand binding studies, it was found that both anandamide and arachidonic acid inhibited the specific binding of [3H]PN 200-110 to transverse tubule membranes with IC(50) values of 4.4+/-0. 7 and 13.4+/-3.5 microM, respectively. These results indicate that anandamide, independent of cannabinoid receptor activation, directly inhibits the function of voltage-dependent calcium channels and modulates the specific binding of calcium channel ligands of the dihydropyridine class.

Endotoxin in pooled pericardial blood contributes to the systemic inflammatory response during cardiac surgery

Although endotoxin has been implicated as an important contributor to the systemic inflammatory response (SIR) during cardiopulmonary bypass (CPB), its source remains unclear. While gut translocation has traditionally been perceived as the primary source of endotoxemia, accumulation of endotoxin in pooled pericardial blood may represent an additional source of endotoxin that is continually reinfused into the CPB circuit. Eighteen patients undergoing primary coronary revascularization procedures were prospectively evaluated. Shed blood pooled in the pericardial space was returned to the CPB circuit through cardiotomy suction catheters at 45 min after placement of the aortic cross-clamp. Simultaneous samples of pooled pericardial and peripheral arterial blood were obtained and analyzed by a limulus amebocyte lysate assay for the determination of endotoxin concentration, and an enzyme-linked immunosorbent assay for tumor necrosis factor (TNF-alpha) levels. Significant elevations in endotoxin were demonstrated in pooled pericardial blood samples compared with arterial blood (3.5 +/- 0.5 vs 0.8 +/- 0.2 pg/ml; p < 0.05). TNF-alpha levels were below the limits of detection in both samples. These data implicate pooled pericardial blood as an important primary source of endotoxin that, when continually reinfused throughout CPB, may contribute to the overall SIR. Because endotoxemia has been identified as an important predictor of adverse outcomes following cardiac surgery, removal of endotoxin antigen in shed pericardial blood, prior to its reinfusion into the CPB circuit, may provide a directed means to improve perioperative outcome without compromising established blood conservation techniques.

Effects of (+) and (-) enantiomers of calcium channel agonist, Bay K 8644, on mechanical and electrical responses of frog skeletal muscle

The effects of (+) and (-) enantiomers of Bay K 8644, a Ca2+ channel agonist, on the mechanical and electrical properties of frog skeletal muscle fibers were investigated. In the concentration range of 10(-6) to 10(-5) M, both (+) and (-) enantiomers of Bay K 8644 significantly increased the maximum amplitudes of twitch responses. Both (+) and (-) enantiomers of Bay K 8644, at higher concentrations such as 10(-4) M, greatly depressed the amplitudes of twitches. Potentiating and depressing effects of (-) enantiomer of Bay K 8644 on twitch responses were significantly greater than those of the (+) enantiomer. At all concentrations used, both (+) and (-) enantiomers of Bay K 8644 significantly decreased the area under the tetanic force x time curve. In intracellular recordings, it was found that the depressing effects of both (+) and (-)-Bay K 8644 on tetanic contractions and twitch responses were due to the inhibition of action potentials. The inhibitory effect of (-) enantiomer of Bay K 8644 on action potentials also was significantly greater than that of the (+) enantiomer. In conclusion, present results suggest that, in contrast with cardiac muscle fibers, (+) and (-) enantiomers of Bay K 8644 have similar inhibitory effects on the electrical and mechanical properties of frog skeletal muscle fibers.

Intravenous immunoglobulin reduces anti-HLA alloreactivity and shortens waiting time to cardiac transplantation in highly sensitized left ventricular assist device recipients

BACKGROUND

Recipients of left ventricular assist devices (LVADs) develop prominent B-cell hyperreactivity. We investigated the influence of anti-HLA antibodies on waiting time to cardiac transplantation in LVAD recipients and compared the effects of 2 immunomodulatory regimens on anti-HLA serum reactivity.

METHODS AND RESULTS

Fifty-five previously nonsensitized LVAD recipients of a TCI device implanted between 1990 and 1996 were studied. Patients with anti-HLA antibodies received monthly courses of either intravenous immunoglobulin (IVIg) or plasmapheresis, in conjunction with cyclophosphamide. The effects of these regimens on anti-HLA alloreactivity and waiting time to transplantation were then determined by Kaplan-Meier log-rank statistics, nonparametric Wilcoxon rank-sum test, and Student's t test. Prolongation in transplant waiting time was related to serum IgG anti-HLA class I alloreactivity. Infusion of IVIg (2 g/kg) caused a mean reduction of 33% in anti-HLA class I alloreactivity within 1 week. Waiting time to transplantation was significantly reduced by IVIg therapy and subsequently approximated that in nonsensitized patients. Side effects of IVIg (2 g/kg) were minimal and related primarily to immune complex disease. Although plasmapheresis caused a similar reduction in alloreactivity to IVIg, this effect was achieved after longer treatment. Moreover, plasmapheresis was associated with an unacceptably high frequency of infectious complications. In patients resistant to low-dose (2 g/kg) IVIg therapy, high-dose (3 g/kg) IVIg was effective in reducing alloreactivity but was associated with a high incidence of reversible renal insufficiency.

CONCLUSIONS

These results indicate that IVIg is an effective and safe modality for sensitized recipients awaiting cardiac transplantation, reducing serum anti-HLA alloreactivity and shortening the duration to transplantation. The therapeutic and safety profile of IVIg would appear to be superior to plasmapheresis.

Quantitative changes in T-cell populations after left ventricular assist device implantation: relationship to T-cell apoptosis and soluble CD95

BACKGROUND

Left ventricular assist devices (LVADs) are currently being evaluated as permanent therapy for end-stage heart failure. Because life-threatening infections limit successful long-term device implantation, we investigated the relationship between quantitative T-cell defects in LVAD recipients and CD95-mediated T-cell apoptosis.

METHODS AND RESULTS

Immunological studies were performed in NYHA class IV patients awaiting cardiac transplantation who received either a TCI Heartmate left ventricular assist device (LVAD) or medical management. Fluorochrome-labeled Mabs were used in T-cell phenotypic analyses. T-cell apoptosis was measured by annexin V binding of T cells cultured in medium for 24 hours. Circulating serum levels of soluble CD95 were measured by ELISA. LVAD recipients had a relative lymphopenia and reduction in CD4 T-cell levels compared with NYHA class IV heart failure controls. These observations were confirmed in a longitudinal study in LVAD recipients, which showed that device implantation was accompanied by progressive and sustained reductions in circulating CD4 T-cell levels. These abnormalities in LVAD recipients were accompanied by increased levels of circulating soluble CD95 and by excessive CD4 and CD8 T-cell apoptosis. Susceptibility to induction of apoptosis was >2-fold greater for CD4 T cells than for CD8 T cells.

CONCLUSIONS

These results suggest that the reduction in CD4 T-cell levels accompanying LVAD implantation is a consequence of an augmented pathway of CD95-mediated apoptosis. The clinical consequences of these abnormalities may include increased prevalence of systemic infections.

Nitric oxide modulates mitochondrial respiration in failing human heart

Background-Our objective for this study was to investigate whether nitric oxide (NO) modulates tissue respiration in the failing human myocardium. Methods and Results-Left ventricular free wall and right ventricular tissue samples were taken from 14 failing explanted human hearts at the time of transplantation. Tissue oxygen consumption was measured with a Clark-type oxygen electrode in an airtight stirred bath containing Krebs solution buffered with HEPES at 37 degrees C (pH 7.4). Rate of decrease in oxygen concentration was expressed as a percentage of the baseline, and results of the highest dose are indicated. Bradykinin (10(-4) mol/L, -21+/-5%), amlodipine (10(-5) mol/L, -14+/-5%), the ACE inhibitor ramiprilat (10(-4) mol/L, -21+/-2%), and the neutral endopeptidase inhibitor thiorphan (10(-4) mol/L, -16+/-5%) all caused concentration-dependent decreases in tissue oxygen consumption. Responses to bradykinin (-2+/-6%), amlodipine (-2+/-4%), ramiprilat (-5+/-6%), and thiorphan (-4+/-7%) were significantly attenuated after NO synthase blockade with N-nitro-L-arginine methyl ester (10(-4) mol/L; all P<0.05). NO-releasing compounds S-nitroso-N-acetyl-penicillamine (10(-4) mol/L, -34+/-5%) and nitroglycerin (10(-4) mol/L, -21+/-5%), also decreased tissue oxygen consumption in a concentration-dependent manner. However, the reduction in tissue oxygen consumption in response to S-nitroso-N-acetyl-penicillamine (-35+/-7%) or nitroglycerin (-16+/-5%) was not significantly affected by N-nitro-L-arginine methyl ester. Conclusions-These results indicate that the modulation of oxygen consumption by both endogenous and exogenous NO is preserved in the failing human myocardium and that the inhibition of kinin degradation plays an important role in the regulation of mitochondrial respiration.