Seasonal Variation in Hip Fracture Mortality

Objectives:

This study aims to identify if wintertime surgery increases the mortality of the patients after hip fracture operations.

Design:

Retrospective observational cohort study.

Setting:

The data for this citywide retrospective observational cohort study came from Clinical Data Analysis Reporting System.

Patient:

This study included 35 409 patients with hip fracture operations from July 2005 to December 2013.

Main Outcome Measures:

Cox regression hazard model was used to estimate the independent effect of operation being performed in winter on the hazard of mortality. The hazard model included covariates found to be independent predictors of mortality: age, sex, surgical delay, and Charlson Comorbidity Index (CCI).

Results:

There was a seasonal variation with more hip fracture operations happening in the winter months. The 1-month, 6-month, 1-year, and 5-year mortality were 3%, 11%, 17%, and 47%, respectively. Operation performed in winter was associated with a higher hazard of mortality (hazard ratio [HR] 1.040; 95% confidence interval: 1.010-1.072; P = .009). The HR was greater with male sex (HR 1.786; P = .000), advanced age (≥85 years old: HR 2.819; P = .000), the longer surgical delay (HR 1.018; P = .000), and higher CCI (severe CCI group: HR 2.963; P = .000).

Conclusion:

Wintertime hip fracture surgery was associated with an increased hazard of mortality after adjusting for other known risk factors affecting mortality post hip fracture operations.

Expression and Purification of Virus-like Particles for Vaccination

Virus-like particles (VLPs) and subviral particles (SVPs) are an alternative approach to viral vaccine design that offers the advantages of increased biosafety and stability over use of live pathogens. Non-infectious and self-assembling, VLPs are used to present structural proteins as immunogens, bypassing the need for live pathogens or recombinant viral vectors for antigen delivery. In this article, we demonstrate the different stages of VLP design and development for future applications in preclinical animal testing. The procedure includes the following stages: selection of antigen, expression of antigen in cell line of choice, purification of VLPs/SVPs, and quantification for antigen dosing. We demonstrate use of both mammalian and insect cell lines for expression of our antigens and demonstrate how methodologies differ in yield. The methodology presented may apply to a variety of pathogens and can be achieved by substituting the antigens with immunogenic structural proteins of the user's microorganism of interest. VLPs and SVPs assist with antigen characterization and selection of the best vaccine candidates.

Delta inulin-derived adjuvants that elicit Th1 phenotype following vaccination reduces respiratory syncytial virus lung titers without a reduction in lung immunopathology

Respiratory syncytial virus (RSV) is a significant cause of lower respiratory tract infections resulting in bronchiolitis and even mortality in the elderly and young children/infants. Despite the impact of this virus on human health, no licensed vaccine exists. Unlike many other viral infections, RSV infection or vaccination does not induce durable protective antibodies in humans. In order to elicit high titer, neutralizing antibodies against RSV, we investigated the use of the adjuvant Advax™, a novel polysaccharide adjuvant based on delta inulin microparticles, to enhance antibody titers following vaccination. BALB/c mice were vaccinated intramuscularly with live RSV as a vaccine antigen in combination with one of two formulations of Advax™. Advax-1 was comprised of the standard delta inulin adjuvant and Advax-2 was formulated delta inulin plus CpG oligodendronucleotides (ODNs). An additional group of mice were either mock vaccinated, immunized with vaccine only, or administered vaccine plus Imject Alum. Following 3 vaccinations, mice had neutralizing antibody titers that correlated with reduction in viral titers in the lungs. Advax-1 significantly enhanced serum RSV-specific IgG1 levels at week 6 indicative of a Th2 response, similar to titers in mice administered vaccine plus Imject Alum. In contrast, mice vaccinated with vaccine plus Advax-2 had predominately IgG2a titers indicative of a Th1 response that was maintained during the entire study. Interestingly, regardless of which Advax^TM adjuvant was used, the neutralizing titers were similar between groups, but the viral lung titers were significantly lower (∼10E+3pfu/g) in mice administered vaccine with either Advax^TM adjuvant compared to mice administered adjuvants only. The lung pathology in vaccinated mice with Advax^TM was similar to Imject Alum. Overall, RSV vaccine formulated with Advax^TM had high neutralizing antibody titers with low lung viral titers, but exacerbated lung pathology compared to unvaccinated mice.

Use of computational and recombinant technologies for developing novel influenza vaccines

Influenza vaccine design has changed considerably with advancements in bioinformatics and computational biology. Improved surveillance efforts provide up-to-date information about influenza sequence diversity and assist with monitoring the spread of epidemics and vaccine efficacy rates. The advent of next-generation sequencing, epitope scanning and high-throughput analysis all help decipher influenza-associated protein interactions as well as predict immune responsiveness based on host genetic diversity. Computational approaches are utilized in nearly all aspects of vaccine design, from modeling, compatibility predictions, and optimization of antigens in various platforms. This overview discusses how computational techniques strengthen vaccine efforts against highly diverse influenza species.

Important tips and numbers on using the cortical step and diameter difference sign in assessing femoral rotation--should we abandon the technique?

Rotational malalignment during femoral nailing is common despite having various intraoperative assessment methods. The cortical step sign and diameter difference sign (CSSDDS) is commonly used because of convenience, yet it lack proper scientific scrutiny and is thought to be error prone. Using a software algorithm, cross-sectional dimensions were obtained from CT scans of 22 intact adult femurs at the proximal, mid and distal diaphysis. With multiple simulated scenarios the sensitivity of CSSDDS was comprehensively determined at all possible C-arm positions. At rotation, cortical width changed most significantly around the thick linea aspera and femoral diameter changed most significantly at the sagittal plane. At 15 degrees of rotation and with the linea aspera in view, CSSDDS thresholds of 0.3mm, 0.6mm and 1mm had sensitivities of 98.8%, 93.1% and 73.8%. With the linea aspera masked behind the femur and out of view, the sensitivities significantly deteriorated to 96.4%, 77.1% and 44.1% respectively. CSSDDS is sufficiently sensitive only when strict rules are followed. It is imperative that the operator position the image intensifier in lateral view under proper magnification so that steps of less than 0.6mm around the linea aspera may be appreciated.

Respiratory syncytial virus (RSV) infection in elderly mice results in altered antiviral gene expression and enhanced pathology

Elderly persons are more susceptible to RSV-induced pneumonia than young people, but the molecular mechanism underlying this susceptibility is not well understood. In this study, we used an aged mouse model of RSV-induced pneumonia to examine how aging alters the lung pathology, modulates antiviral gene expressions, and the production of inflammatory cytokines in response to RSV infection. Young (2-3 months) and aged (19-21 months) mice were intranasally infected with mucogenic or non-mucogenic RSV strains, lung histology was examined, and gene expression was analyzed. Upon infection with mucogenic strains of RSV, leukocyte infiltration in the airways was elevated and prolonged in aged mice compared to young mice. Minitab factorial analysis identified several antiviral genes that are influenced by age, infection, and a combination of both factors. The expression of five antiviral genes, including pro-inflammatory cytokines IL-1β and osteopontin (OPN), was altered by both age and infection, while age was associated with the expression of 15 antiviral genes. Both kinetics and magnitude of antiviral gene expression were diminished as a result of older age. In addition to delays in cytokine signaling and pattern recognition receptor induction, we found TLR7/8 signaling to be impaired in alveolar macrophages in aged mice. In vivo, induction of IL-1β and OPN were delayed but prolonged in aged mice upon RSV infection compared to young. In conclusion, this study demonstrates inherent differences in response to RSV infection in young vs. aged mice, accompanied by delayed antiviral gene induction and cytokine signaling.

Hyaluronic acid instillation following arthroscopic anterior cruciate ligament reconstruction: a double-blinded, randomised controlled study

PURPOSE

To assess the effect of hyaluronic acid instillation after arthroscopic anterior cruciate ligament (ACL) reconstruction for improving pain, range of movement, and function of the knee.

METHODS

28 men and 4 women underwent arthroscopic ACL reconstruction for isolated ACL rupture (partial or complete) and instability after recreational sports injury 2 to 120 months earlier. They were randomised to undergo arthroscopic ACL reconstruction followed by intra-articular viscoseal instillation (13 men and 3 women) or arthroscopic ACL reconstruction alone (15 men and 1 woman). The knee injury osteoarthritis outcome score (for pain, symptoms, activities of daily living, sport and recreation function, and quality of life), range of movement, knee circumference, and analgesic use were assessed on days -1, 1, and 2, and weeks 2, 6 and 12.

RESULTS

Patient demographics were similar at baseline. At postoperative days 1 and 2, all subscales of the knee injury osteoarthritis outcome score (except for quality of life) were significantly higher in the viscoseal group. At weeks 2, 6, and 12, improvement in both groups equalised. Knee swelling (change in knee circumference) was significantly less in the viscoseal group at days 1 and 2 (p=0.009 and p=0.038, respectively, Mann-Whitney U test). Only one patient in the viscoseal group had a limited range of movement. No patient developed any adverse reaction.

CONCLUSION

Intra-articular viscoseal instillation improved pain control and swelling 2 days after arthroscopic ACL reconstruction.

Antihypertensive and anti-arrhythmic effects of an extract of Radix Stephaniae Tetrandrae in the rat

In this study, we determined the effects of an extract of Radix Stephaniae Tetrandrae (RST) on arterial blood pressure and heart weight in deoxycorticosterone acetate-salt (DOCA-salt) hypertensive rats. We also determined the effects of the extract on arrhythmia and infarct induced by myocardial ischaemia and reperfusion in anaesthetized rats. We further compared the effects of the extract with those of tetrandrine, which makes up 7% of the extract and is known to act as a calcium-channel antagonist, and verapamil, a prototype calcium-channel antagonist. Treatment with RST extract returned the arterial blood pressure, cardiac compliance and coronary flow towards normal, and reduced right ventricular hypertrophy in the DOCA-salt hypertensive rat. In the anaesthetized rat, the RST extract reduced arrhythmia and infarct size induced by myocardial ischaemia and reperfusion; the effects were similar to those of tetrandrine and verapamil. The findings indicate that the RST extract acts like a calcium-channel antagonist. It may be used in the treatment of cardiovascular diseases, as are the calcium-channel antagonist and tetrandrine. More interestingly, the effects of the RST extract were of the same potency as tetrandrine. Since only 7% of the extract was tetrandrine, the observation indicates that tetrandrine was not the only component that was responsible for the actions of the extract.

Oestrogen confers cardioprotection by suppressing Ca2+/calmodulin-dependent protein kinase II

BACKGROUND AND PURPOSE

Oestrogen confers cardioprotection by down-regulating the beta(1)-adrenoceptor and suppressing the expression and activity of protein kinase A. We hypothesized that oestrogen may also protect the heart by suppressing Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), another signalling messenger activated by the beta(1)-adrenoceptor, that enhances apoptosis.

EXPERIMENTAL APPROACH

We first determined the expression of CaMKII in the heart from sham and ovariectomized rats with and without oestrogen replacement. We then determined the effects of CaMKII inhibition (KN93, 2.5 micromolxL(-1)) in the presence or absence of 10(-7) molxL(-1) isoprenaline, a non-selective beta-adrenoceptor agonist. We also determined the percentage apoptosis in myocytes from rats in each group with or without beta-adrenoceptor stimulation.

KEY RESULTS

Both CaMKIIdelta and phosphorylated CaMKII were up-regulated in the hearts from ovariectomized rats, and they were restored to normal by oestrogen replacement. The infarct size and lactate dehydrogenase release were significantly greater after ovariectomy. Similarly, cardiac contractility, the amplitude of the electrically induced intracellular Ca(2+) transient and the number of apoptotic cells were also greater in ovariectomized rats upon ischaemia/reperfusion in the presence or absence of isoprenaline. Most importantly, the responses to ischaemic insult in ovariectomized rats were reversed not only by oestrogen replacement, but by blockade of CaMKII with KN93.

CONCLUSIONS AND IMPLICATIONS

Oestrogen confers cardioprotection at least partly by suppressing CaMKIIdelta. This effect of oestrogen on CaMKII is independent of the beta-adrenoceptor and occurs in addition to down-regulation of the receptor.

Testosterone protects rat hearts against ischaemic insults by enhancing the effects of alpha(1)-adrenoceptor stimulation

BACKGROUND AND PURPOSE

Testosterone alleviates symptoms in patients with ischaemic heart disease. Androgen receptors are present in the heart, and testosterone upregulates gene expression of cardiac beta(1)-adrenoceptors. We hypothesize that testosterone may confer cardioprotection by interacting with adrenoceptors.

EXPERIMENTAL APPROACH

In isolated perfused hearts and ventricular myocytes from orchidectomized rats without or with testosterone (200 microg/100 g) replacement, we first determined the effect of ischaemia/reperfusion in the presence of noradrenaline (10(-7) M). Then we determined the contribution of interactions between testosterone and alpha(1)- or beta(1)-adrenoceptors in cardiac injury/protection (infarct size, release of lactate dehydrogenase, viability of myocytes, recovery of contractile function and incidence of arrhythmias) upon ischaemia/reperfusion by pharmacological manipulation using selective adrenoceptor agonists (alpha(1)-adrenoceptor agonist: phenylephrine 10(-6) M; non-selective beta-adrenoceptor agonist: isoprenaline 10(-7) M) and antagonists (alpha(1): prazosin or benoxathian 10(-6) M; beta(1): CGP 20712A 5 x 10(-7) M). We also determined the expression of alpha(1) and beta(1)-adrenoceptor in the hearts from rats with and without testosterone.

KEY RESULTS

Testosterone reduced injury induced by ischaemia/reperfusion and noradrenaline. This was achieved by enhancing the beneficial effect of alpha(1)-adrenoceptor stimulation, which was greater than the deleterious effect of beta(1)-adrenoceptor stimulation (also enhanced by testosterone). The effects of testosterone were abolished or attenuated by blockade of androgen receptors. Testosterone also enhanced the expression of alpha(1A) and beta(1)-adrenoceptor.

CONCLUSIONS AND IMPLICATIONS

Testosterone conferred cardioprotection by upregulating the cardiac alpha(1)-adrenoceptor and enhancing the effects of stimulation of this adrenoceptor. The effect of testosterone was at least partly mediated by androgen receptors.

Remifentanil preconditioning confers delayed cardioprotection in the rat †

BACKGROUND

Preconditioning with remifentanil (RPC) provides immediate cardioprotection in rats via all three types of opioid (OP) receptor. This study sought to investigate whether remifentanil also confers delayed cardioprotection via OP receptors.

METHODS

Male rats received preconditioning either by ischaemia (IPC; 5 min occlusion, 5 min reperfusion x 3) or with remifentanil (RPC; 1, 5, 10, and 20 microg kg(-1) min(-1), 20 min infusion). After 24 h, all animals were subjected to 30 min occlusion of the left coronary artery and 2 h of reperfusion. Subsequently, the time-course effect of RPC (10 microg kg(-1) min(-1), 20 min infusion) was determined at 12, 16, 24, 32, 36, and 48 h intervals, using the same experimental procedure. The effect of RPC (10 microg kg(-1) min(-1), 20 min infusion) and IPC in the presence of selective OP receptor antagonists was evaluated at the 24 h interval. Infarct size (IS), as a percentage of the area at risk (AAR), was determined.

RESULTS

Pre-treatment with remifentanil at 1, 5, 10, and 20 microg kg(-1) min(-1) significantly reduced the IS/AAR at 24 h with the maximum effect at 10 microg kg(-1) min(-1). Remifentanil at 10 microg kg(-1) min(-1) significantly reduced the IS at 12 h [32.5 (sd 9.1)%]; 16 h [26.1 (2.8)%]; 24 h [19.5 (5.0)%]; 32 h [31.2 (9.1)%]; and 36 h [36.4 (9.4)%] after drug administration. The maximal reduction in IS was seen at 24 h and the effect completely disappeared at 48 h [36.4 (9.4)%]. The protective effect of RPC was abolished or significantly attenuated by blockade of any of the three OP receptors with selective antagonists.

CONCLUSIONS

Like IPC, remifentanil produces delayed cardioprotection in anaesthetized rats 12-36 h after administration. The protective effect is mediated via all three OP receptors.

Role of opioid receptors in cardioprotection of cold-restraint stress and morphine

Since cold exposure confers cardioprotection, the present study attempted to determine the role of opioid receptors (OR). Stress with cold exposure and restraint for 3 h, shown previously to induce peptic ulcer in a synergistic manner, attenuated infarct size induced by myocardial ischemia and reperfusion in the isolated perfused rat heart from 36.64 +/- 1.8 to 22.85 +/- 2.6%. This is similar to protecting the rat with morphine at 8 mg/kg, which also attenuated the infarct size from 36.26 +/- 1.6 to 20.30 +/- 2.1%. The effects of cold-restraint or morphine were abolished by naloxone, a non-selective OR antagonist; nor-binaltorphimine, a selective kappa-OR antagonist; naltrindole, a selective delta-OR antagonist, or CTOP, a selective mu-OR antagonist. The effects were also attenuated by blockade of protein kinase C or the mitochondrial K(ATP) channel. The finding is first evidence that all three OR subtypes mediate cardioprotection of cold-restraint stress in the rat.

[The antiarrhythmic effect of (-)-U-50,488 in rats with acute ischemia and reperfusion of heart is mediated by kappa1-opioid receptor activation]

Pretreatment with a selective kappa1 opioid receptor (OR) agonist (-)-U-50,488 (1 mg/kg, i.v.) prevented the development of arrhythmias induced by occlusion (10 min) and reperfusion (10 min) in ketamine anesthetized rats, while the treatment with a less active enantiomer (+)-U-50,488 in the same dose produced no such effects. Preliminary intravenous administration of a selective kappa1 OR antagonist norbinaltorphimine (9 mg/kg) fully abolished the antiarrhythmic effect of (-)-U-50,488, while the kappa2 OR antagonist quadazocine (3 mg/kg) did not eliminate this effect. The injections of norbinaltorphimine or quadazocine alone did not influence the incidence of model arrhythmias caused by the occlusion and reperfusion. It was concluded that kappa1 OR stimulation favors an increase in cardiac tolerance to the arrhythmogenic action of occlusion and reperfusion.

Correlation between magnetic resonance imaging and radiographic measurement of cervical spine in cervical myelopathic patients

PURPOSE

To correlate the radiographic measurement, cord diameter shown on magnetic resonance imaging (MRI), and clinical hand sign of cervical myelopathic patients.

METHODS

Patients with clinical cervical myelopathy who had had MRI in Kwong Wah Hospital between January 2001 and December 2002 were enlisted. Their cervical spine radiographs and clinical records were reviewed.

RESULTS

Of 36 patients with a complete set of MRI films, cervical spine radiographs, and clinical notes; 18% did not have Hoffman's sign, 47% had normal supinator reflex, 39% had unimpaired 10-second test, and 45% showed no finger escape sign. The presence of myelopathic hand signs was not correlated to any radiological assessment, cord diameter, or presence of myelomalacia at any level.

CONCLUSION

Cervical spine radiography cannot predict the level and degree of cervical spinal cord compression. Myelopathic hand signs are not diagnostically fail-safe and cannot predict the level and degree of cord compression.

Failure to confer cardioprotection and to increase the expression of heat-shock protein 70 by preconditioning with a kappa-opioid receptor agonist during ischaemia and reperfusion in streptozotocin-induced diabetic rats

AIMS/HYPOTHESIS

The aim of this study was to determine the effects of preconditioning on injury and expression of heat shock proteins 70 in diabetic rat hearts.

METHODS

Diabetes was induced by an intraperitoneal injection of 65 mg kg(-1) streptozotocin. Daily subcutaneous injection of 4 IU insulin started 2 weeks after streptozotocin treatment for 4 weeks. Rats were preconditioned by intravenous injection of 10 mg kg(-1) U50,488H, a selective kappa-opioid receptor agonist (U50,488H preconditioning). The effects of U50,488H preconditioning had previously been shown to be blocked by a selective kappa-opioid receptor antagonist, nor-binaltorphimine. Twenty-four hours later, rats were subjected to 30 min of regional ischaemia by occlusion of the left coronary artery followed by 4 h of reperfusion. Infarct size was determined at the end of reperfusion. Stress-inducible and constitutive heat shock proteins 70 were analysed at the end of ischaemia and reperfusion by Western blotting.

RESULTS

Myocardial infarcts induced by ischaemia and reperfusion were greater in diabetic rats. U50,488H preconditioning significantly reduced the infarct size and increased the expression of stress-inducible heat-shock protein 70 in normal rats. The effects of U50,488H preconditioning were abolished in streptozotocin-induced diabetic rats, but restored by insulin replacement.

CONCLUSION/INTERPRETATION

In addition to a greater susceptibility to ischaemic insults, the delayed cardioprotection of U50,488H preconditioning was lost, which could at least partly be due to impaired synthesis of stress-inducible heat-shock protein 70 in diabetic rats.

Effects of pharmacological preconditioning with U50488H on calcium homeostasis in rat ventricular myocytes subjected to metabolic inhibition and anoxia

1. The effects of pharmacological preconditioning with U50488H (U(50)), a selective kappa-opioid receptor agonist, on Ca(2+) homeostasis in rat ventricular myocytes subjected for 9 min to metabolic inhibition (MI) and anoxia (A), consequences of ischaemia, were studied and compared with those of preconditioning with brief periods of MI/A. 2. Precondition with 30 micro M of U(50) for three cycles of 1 min each cycle separated by 3 min of recovery (UP) significantly increased the percentage of non-blue cells following MI/A. The effect of UP is the same as that of preconditioning with an inhibitor of glycolysis and an oxygen scavenger for three 1-min cycles separated by three-minute recovery (MI/AP). The results indicate that like MI/AP, UP also confers cardioprotection. 3. MI/A increased intracellular Ca(2+) ([Ca(2+)](i)) and reduced the amplitude of caffeine-induced [Ca(2+)](i) transients, an indication of Ca(2+) content in the sarcoplasmic reticulum (SR). MI/A also reduced the electrically-induced [Ca(2+)](i) transient, that indicates Ca(2+)-release during excitation-contraction coupling, and Ca(2+) sparks in unstimulated myocytes, that indicates spontaneous Ca(2+)-release from SR. It also prolonged the decline of the electrically-induced [Ca(2+)](i) transient and slowed down the recovery of the electrically-induced [Ca(2+)](i) transient after administration of caffeine. In addition, MI/A prolonged the decline of caffeine induced [Ca(2+)](i) transient, an indication of Na(+)-Ca(2+) exchange activity, and UP prevented it. So UP, that confers cardioprotection, prevented the changes induced by MI/A. With the exception of Ca(2+)-spark, which was not studied, the effects of MI/AP are the same as those of UP. 4. It is concluded that pharmacological preconditioning with U(50), that confers immediate cardioprotection, prevents changes of Ca(2+) homeostasis altered by MI/A in the rat heart. This may be responsible, at least partly, for the cardioprotective action. 5. The study also provided evidence that MI/A causes mobilization of Ca(2+) from SR to cytoplasm causing Ca(2+)-overload which may be due to reduced Ca(2+)-uptake by SR. MI/A also reduces spontaneous and electrically induced Ca(2+) release from SR.

Protein kinase C-epsilon is a trigger of delayed cardioprotection against myocardial ischemia of kappa-opioid receptor stimulation in rat ventricular myocytes

Kappa-opioid receptor (OR) stimulation with a selective agonist, U50,488H (U50), known to mediate the delayed cardioprotection of metabolic inhibition preconditioning (MIP) against cell injury/death in rat ventricular myocytes, has been shown to act via protein kinase C (PKC). We attempted to identify the PKC isoform(s) that is activated, thus triggering delayed cardioprotection of MIP and pretreatment with 10 microM U50 (U50 pretreatment, UP). Release of lactate dehydrogenase and exclusion of trypan blue by isolated rat ventricular myocytes were used as indices of cell injury and death, respectively. Both MIP and UP induced translocation of PKC-epsilon, but not other PKC isoforms, -alpha and -delta, from cytosolic to membrane fractions. This was accompanied by reductions in cell injury/death induced by lethal simulated ischemia. The effects of MIP and UP were attenuated and abolished by 1 microM nor-binaltorphimine, a selective kappa-OR antagonist, administered before and during preconditioning/pretreatment, respectively. The effects were mimicked by 10 nM phorbol-12-myristate-13-acetate, a PKC activator, but attenuated by 5 microM chelerythrine, a PKC inhibitor. More importantly, 0.1 microM epsilonV1-2, a selective PKC-epsilon inhibitor administered before and during MIP/UP, also attenuated the effects of both treatments on cell injury/death and translocation of PKC-epsilon. On the other hand, 5 microM rottlerin, a selective PKC-delta inhibitor, did not alter the effects of either treatment on injury/death. The results indicate that both MIP and UP activate PKC-epsilon, leading to delayed cardioprotection in rat ventricular myocytes.

Signaling pathway mediated by kappa-opioid receptor is impaired in cardiac hypertrophy

AIM

The responses of the intracellular calcium ([Ca2+]i) and the intracellular pH (pHi) to kappa-opioid receptor stimulation were determined in the single right ventricular myocytes isolated from the hearts of chronically hypoxic rats which exhibited right ventricular hypertrophy (RVH).

METHODS

With the spectrofluorometric method, the electrically-induced [Ca2+]i transient and pHi were measured in myocytes loaded with fura-2 and BCECF [2',7'-bis-(2-carboxyethyl)-5-(and 6)-carboxyfluorscein], respectively.

RESULTS

U50,488H, a selective kappa-opioid agonist decreased the electrically-induced [Ca2+]i transient and increased the pHi. The effect of U50,488H was mediated by protein kinase C (PKC). In the RVH, the effect of U50,488H on the [Ca2+]i transient and the pHi were significantly attenuated. In parallel, 4-phorbol 12-myristate 13-acetate (PMA), an activator of PKC, also decreased the [Ca2+]i transient and increased the pHi. In the RVH, the effects of PMA were blunted. The recovery of pHi, which was blocked by ethylisopropyl-amiloride (EIPA), following an acid loading induced by washout of 10 mmol/L NH4)Cl exposing to the cells for 10 min was the same in the RVH and control myocytes.

CONCLUSION

kappa-Opioid receptor signaling was impaired in the cardiac hypertrophy due to a defect in the coupling of PKC signaling with its effector.

Kappa-opioid receptor agonist inhibits the cholera toxin-sensitive G protein in the heart

To explore the signaling mechanisms of the negative modulation of beta-adrenoceptors by kappa-Opioid receptors (kappa-OR) in the heart, the possibility of the interaction at the level of G protein and receptor was determined. Cholera toxin, an activator of the stimulatory G protein (Gs), elevated electrically induced intracellular Ca2+ ([Ca2+]i) transients and induced ribosylation of the alpha-subunit of Gs (Gsalpha) in rat ventricular myocytes. The effects were significantly attenuated by U50,488H, a specific agonist of kappa-OR, and were abolished by nor-binaltorphimine, a selective kappa-OR antagonist. The content of Gsalpha, however, was not affected by U50,488H. Receptor binding experiments showed that neither Bmax nor Kd of the binding of [3H]CGP-12177, a beta-adrenoceptor antagonist, was affected by U50,488H. The current study provides the first evidence that kappa-OR stimulation inhibits the ribosylation of the alpha-subunit of the Gs protein, thus inhibiting the action of cholera toxin on the protein.

Inducible HSP70 mediates delayed cardioprotection via U-50488H pretreatment in rat ventricular myocytes

To test the hypothesis that heat-shock proteins (HSPs) mediate delayed cardioprotection of prior kappa-opioid receptor (kappa-OR) stimulation, we first correlated cellular injury and viability with the expression of HSP70s in isolated rat ventricular myocytes subjected to prior kappa-OR stimulation with the selective agonist trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide (U-50488H) and delayed lethal simulated ischemia (LSI). Cell injury and viability were indicated by lactate dehydrogenase release and trypan blue exclusion, respectively. The reduced injury and increased viability after pretreatment with U-50488H were concentration dependent and correlated directly with the expression of both stress-inducible (HSP70) and constitutive (HSC70) proteins. The effects mimic those with metabolic inhibition preconditioning (MIP). The cardioprotection against LSI by pretreatment with U-50488H and MIP was abolished and antagonized, respectively, via blockade of the kappa-OR by its selective antagonist, nor-binaltorphimine. We also found that blockade of the production of HSP70 but not HSC70 blocked the inhibitory effect of pretreatment with U-50488H on injury and viability. These observations provide evidence that stress-inducible HSP70 mediates delayed cardioprotection of prior kappa-OR stimulation.

Modulation of sympathetic actions on the heart by opioid receptor stimulation

The sympathetic nervous system, the most important extrinsic regulatory mechanism of the heart, is inhibited postsynaptically and presynaptically by opioid peptides produced in the heart via their respective receptors. The cardiac actions of beta-adrenergic receptor (beta-AR) stimulation are attenuated by activation of the opioid receptor (OR) with OR agonist at ineffective concentrations, implying cross-talk between the OR and beta-AR. This cross-talk results from inhibition of the Gs protein and adenylyl cyclase of the beta-AR pathway by the pertussis toxin-sensitive G protein of the opioid pathway. Alterations in cross-talk between these two receptors occur in pathological situations to meet bodily needs. In myocardial ischemia, when the sympathetic activity is increased, the inhibition of beta-AR stimulation by kappa-opioid stimulation is also enhanced, thus reducing the workload, oxygen consumption and cardiac injury. Whereas cardiac responsiveness to sympathetic discharges is also reduced after chronic hypoxia, the cross-talk between kappa-OR and beta-AR is reduced to prevent undue suppression of the sympathetic influence on the heart. On the other hand, impairment of the cross-talk may result in abnormality. A lack or a significant reduction in the inhibition of beta-AR stimulation by kappa-OR stimulation may lead to an excessive increase in cardiac activities, which contribute to the maintenance of high arterial blood pressure in spontaneously hypertensive rats. Other than opioid peptides, female sex hormone and adenosine also inhibit the sympathetic actions on the heart. In addition, sympathetic action is also inhibited presynaptically by kappa-opioid peptides via their receptor.

Cardiac effects of the extract and active components of Radix stephaniae tetrandrae. I. Electrically-induced intracellular calcium transient and protein release during the calcium paradox

The present study was designed to compare the cardiac actions of the extract and individual components, tetrandrine (Tet) and fangchinoline (Fan), of Radix stephaniae tetrandrae (RST). We measured the electrically induced [Ca2+]i transient in single rat ventricular myocytes and protein release following perfusion with a Ca2+ free solution (the Ca2+ paradox) from the isolated perfused rat heart, both of which are known to relate to Ca2+ influx. We found that Tet inhibited both electrically induced [Ca2+]i transient and protein release during the Ca2+ paradox, while Fan had no significant effects. The RST extract containing 9% Tet and 6% Fan by weight also affected the [Ca2+]i transient, and was only slightly, though significantly, less effective/potent than Tet alone. On the other hand, RST extract had a significantly greater inhibitory effect on protein release during the Ca2+ paradox than Tet alone. The observations suggest that the RST extract, which contains a mixture of components, may have more potent effects in the heart than its main active component.

Cardiac effects of the extract and active components of radix stephaniae tetrandrae. II. Myocardial infarct, arrhythmias, coronary arterial flow and heart rate in the isolated perfused rat heart

The primary purpose of the present study was to compare the cardioprotective effects of the extract from radix stephaniae tetrandrae (RST) and its individual compounds, tetrandrine (Tet) and fanchinoline (Fan). Secondly, we also compared the cardiac effects of the individual compounds and the RST extract with those of verapamil, a classical Ca2+ channel blocker. The Langendorff isolated perfused rat heart preparation was used. Regional ischaemia and reperfusion was employed to induce myocardial infarct and arrhythmia. Infarct, arrhythmia, heart rate and coronary artery flow were determined in hearts treated with vehicle, RST extract, Tet, Fan, or verapamil. It was found that RST extract, of which only 9% was Tet, and Tet alone produced equally potent ameliorating effects on arrhythmia and infarct induced by ischaemia and reperfusion without further inhibiting ischaemia-reduced heart rate and coronary artery flow. Fan had no effects on arrhythmia and infarct induced by ischaemia and reperfusion; but it induced S-T segment elevation and further reduced heart rate and coronary artery flow during ischaemia. Verapamil also ameliorated the effects of ischaemia and reperfusion on arrhythmia and infarct. It should be noted that 1 microM verapamil, that produced comparable effects on infarct and arrhythmia to the RST extract and Tet, further inhibited heart rate during ischaemia. The results indicate that the RST extract produces equally potent cardioprotective and anti-arrhythmic effects as Tet alone. Both RST extract and Tet may be better choices for the treatment of arrhythmia and infarct induced by myocardial ischaemia and reperfusion than the classical Ca2+ channel blocker, verapamil as they do not further reduce heart rate during ischaemia.

Kappa- but not delta-opioid receptors mediate effects of ischemic preconditioning on both infarct and arrhythmia in rats

Two series of experiments were performed in the isolated perfused rat heart to determine the role of kappa- and delta-opioid receptors (OR) in cardioprotection of ischemic preconditioning (IP). In the first series of experiments, it was found that IP with two cycles of 5-min regional ischemia followed by 5-min reperfusion each reduced infarct size induced by 30-min ischemia, and the ameliorating effect of IP on infarct was attenuated with blockade of either 5 x 10(-6) mol/l nor-binaltorphimine (nor-BNI), a selective kappa-OR antagonist, or 5 x 10(-6) mol/l naltrindole (NTD), a selective delta-OR antagonist. The second series showed that U50,488H, a selective kappa-OR agonist, or D-Ala(2)-D-leu(5)-enkephalin (DADLE), a selective delta-OR agonist, dose dependently reduced the infarct size induced by ischemia, which mimicked the effects of IP. The effect of 10(-5) mol/l U50,488H on infarct was significantly attenuated by blockade of protein kinase C (PKC) with specific PKC inhibitors, 5 x 10(-6) mol/l chelerythrine or 8 x 10(-7) mol/l calphostin C, as well as by blockade of ATP-sensitive K(+) (K(ATP)) channels with blockers of the channel, 10(-5) mol/l glibenclamide or 10(-4) mol/l 5-hydroxydecanoate. IP also reduced arrhythmia induced by ischemia. Nor-BNI, but not NTD, attenuated, while U50,488H, but not DADLE, mimicked the antiarrhythmic action of IP. In conclusion, the present study has provided first evidence that kappa-OR mediates the ameliorating effects of IP on infarct and arrhythmia induced by ischemia, whereas delta-OR mediates the effects only on infarct. Both PKC and K(ATP) channels mediate the effect of activation of kappa-OR on infarct.

Kappa- but not delta-opioid receptors mediate effects of ischemic preconditioning on both infarct and arrhythmia in rats

Two series of experiments were performed in the isolated perfused rat heart to determine the role of kappa- and delta-opioid receptors (OR) in cardioprotection of ischemic preconditioning (IP). In the first series of experiments, it was found that IP with two cycles of 5-min regional ischemia followed by 5-min reperfusion each reduced infarct size induced by 30-min ischemia, and the ameliorating effect of IP on infarct was attenuated with blockade of either 5 x 10(-6) mol/l nor-binaltorphimine (nor-BNI), a selective kappa-OR antagonist, or 5 x 10(-6) mol/l naltrindole (NTD), a selective delta-OR antagonist. The second series showed that U50,488H, a selective kappa-OR agonist, or D-Ala(2)-D-leu(5)-enkephalin (DADLE), a selective delta-OR agonist, dose dependently reduced the infarct size induced by ischemia, which mimicked the effects of IP. The effect of 10(-5) mol/l U50,488H on infarct was significantly attenuated by blockade of protein kinase C (PKC) with specific PKC inhibitors, 5 x 10(-6) mol/l chelerythrine or 8 x 10(-7) mol/l calphostin C, as well as by blockade of ATP-sensitive K(+) (K(ATP)) channels with blockers of the channel, 10(-5) mol/l glibenclamide or 10(-4) mol/l 5-hydroxydecanoate. IP also reduced arrhythmia induced by ischemia. Nor-BNI, but not NTD, attenuated, while U50,488H, but not DADLE, mimicked the antiarrhythmic action of IP. In conclusion, the present study has provided first evidence that kappa-OR mediates the ameliorating effects of IP on infarct and arrhythmia induced by ischemia, whereas delta-OR mediates the effects only on infarct. Both PKC and K(ATP) channels mediate the effect of activation of kappa-OR on infarct.

kappa-Opioid receptor potentiates apoptosis via a phospholipase C pathway in the CNE2 human epithelial tumor cell line

The mechanism by which kappa-opioid receptor (kappaor) modulated apoptosis was investigated in CNE2 human epithelial tumor cells. Induction of these cells to undergo apoptosis with staurosporine was associated with a massive increase in intracellular cAMP level. The inhibition of the increase in cAMP partially inhibited apoptosis as evidenced by a reduction of PARP and caspase-3 cleavage. Accordingly, a low but significant level of apoptosis is induced in these cells by the elevation of cAMP through the addition of forskolin and isobutylmethylxanthine. The existence of a cAMP-dependent and a cAMP-independent apoptotic pathway is therefore suggested. Receptor binding studies, RT-PCR experiments and Western blot analysis demonstrated the presence of type 1 kappaor in the CNE2 cells. Stimulation of kappaor in these cells resulted in the production of inositol (1,4,5)-trisphosphate, reduction of cAMP level and a marked enhancement of staurosporine-induced apoptosis. The potentiation of apoptosis by kappaor was prevented by inhibition of phospholipase C but was slightly enhanced by the presence of the active cAMP analogues, 8-CPT-cAMP and dibutyryl-cAMP. These data demonstrate for the first time that the phospholipase C pathway activated by type 1 kappaor expressed by cancer cells is involved in the potentiation of apoptosis.

Cardiovascular actions of Radix Stephaniae Tetrandrae: a comparison with its main component, tetrandrine

A comparison of the cardiovascular actions of the extract of Radix Stephaniae Tetrandrae (RST), the root of a Chinese hero Stephania tetrandra S Moore, in rats with those of tetrandrine (Tet), the best known active component of RST was reviewed. The RST extract inhibits Ca2+ influx into the myocyte and reduces protein release during reperfusion with a Ca2+ containing solution following perfusion with a Ca2+ free solution (Ca2+ paradox), and arrhythmia during reperfusion in the isolated perfused heart. It also reduces the infarct size induced by ischemia/reperfusion in vitro and in vivo. In addition, the RST extract suppresses elevation of arterial blood pressure in DOCA-salt hypertensive rats. It does not further reduce the heart rate and coronary flow significantly during myocardial ischemia. The effects are similar to those of Tet. When compared with the same doses of Tet alone, the RST extract, of which 9% is Tet, produces equally potent effects on infarction, arrhythmias, coronary flow and heart rate, and has a greater inhibitory effect on protein release during Ca2+ paradox. The combination at 1:1 ratio of Tet and fangchinoline (Fan), another main component, which constitutes 6% of the RST extract and has no significant effects on the heart, produces comparable effects on protein release during Ca2+ paradox as Tet alone. The observations suggest that the efficacy of the RST extract cannot be accounted for by Tet alone. Some of the effects may be due to an interaction between the components of the extract. The RST extract also produces similar effects as verapamil, a prototype Ca2+ channel antagonist widely used in the treatment of ischemic heart diseases and hypertension, except that verapamil, at 1 mumol/L, a concentration that produces similar cardiac effects as the RST extract, further reduces heart rate significantly during ischemia. So the RST extract may be a therapeutically better agent in the treatment of ischemic heart diseases and hypertension than Ca2+ channel antagonists because of the absence of the inhibitory effect on heart rate during myocardial ischemia.

Impaired G(s)alpha and adenylyl cyclase cause beta-adrenoceptor desensitization in chronically hypoxic rat hearts

The effects of beta-adrenoceptor stimulation with isoproterenol on electrically induced contraction and intracellular calcium ([Ca(2+)](i)) transient, and cAMP in myocytes from both hypertrophied right and nonhypertrophied left ventricles of rats exposed to 10% oxygen for 4 wk, were significantly attenuated. The increased [Ca(2+)](i) transient in response to cholera toxin was abolished, whereas increased cAMP after NaF significantly attenuated. The biologically active isoform, G(s)alpha-small (45 kDa), was reduced while the biologically inactive isoform, G(s)alpha-large (52 kDa), increased. The increased electrically induced [Ca(2+)](i) transient and cAMP with 10-100 microM forskolin were significantly attenuated in chronically hypoxic rats. The content of G(i)alpha(2), the predominant isoform of G(i) protein in the heart, was unchanged. Results indicate that impaired functions of G(s) protein and adenylyl cyclase cause beta-adrenoceptor desensitization. The impaired function of the G(s) protein may be due to reduced G(s)alpha-small and/or increased G(s)alpha-large, which does not result from changes in G(i) protein. Responses to all treatments were the same for right and left ventricles, indicating that the impaired cardiac functions are not secondary to cardiac hypertrophy.

Impaired [Ca(2+)](i) and pH(i) responses to kappa-opioid receptor stimulation in the heart of chronically hypoxic rats

kappa-Opioid receptor (kappa-OR) stimulation with U50,488H, a selective kappa-OR agonist, or activation of protein kinase C (PKC) with 4-phorbol 12-myristate 13-acetate (PMA), an activator of PKC, decreased the electrically induced intracellular Ca(2+) ([Ca(2+)](i)) transient and increased the intracellular pH (pH(i)) in single ventricular myocytes of rats subjected to 10% oxygen for 4 wk. The effects of U50,488H were abolished by nor-binaltorphimine, a selective kappa-OR antagonist, and calphostin C, a specific inhibitor of PKC, while the effects of PMA were abolished by calphostin C and ethylisopropylamiloride (EIPA), a potent Na(+)/H(+) exchange blocker. In both right hypertrophied and left nonhypertrophied ventricles of chronically hypoxic rats, the effects of U50,488H or PMA on [Ca(2+)](i) transient and pH(i) were significantly attenuated and completely abolished, respectively. Results are first evidence that the [Ca(2+)](i) and pH(i) responses to kappa-OR stimulation are attenuated in the chronically hypoxic rat heart, which may be due to reduced responses to PKC activation. Responses to all treatments were the same for right and left ventricles, indicating that the functional impairment is independent of hypertrophy. kappa-OR mRNA expression was the same in right and left ventricles of both normoxic and hypoxic rats, indicating no regional specificity.

kappa -opioid receptor stimulation induces arrhythmia in the isolated rat heart via the protein kinase C/Na(+)-H(+)exchange pathway

The present study attempted to determine whether the protein kinase C (PKC)/Na(+)-H(+)exchange (NHE) pathway would mediate the arrhythmogenic action of kappa -opioid receptor (OR) stimulation. We first determined the effects of U50,488H, a selective kappa -OR agonist, on PKC activity and cardiac rhythm in the isolated perfused rat heart, and intracellular pH (pH(i)), and Ca(2+)([Ca(2+)](i)) and Na(+)([Na(+)](i)) concentrations in the isolated ventricular myocyte. At 5-40 microm U50,488H concentration dependently increased the particulate PKC activity and pH(i), and induced arrhythmia. 40 microm U50,488H also increased [Na(+)](i)and [Ca(2+)](i). The arrhythmogenic effects of 40 microm U50,488H were abolished by nor-binaltorphimine, a selective kappa -OR antagonist. Blockade of PKC and NHE with respective blockers, 1 microm bisindolylmaleimide I or 0.5 microm calphostin C, and 1 microm 5-[N -methyl- N -isobutyl]amiloride or 1 microm 5-([N -ethyl- N -isopropopyl]amiloride, abolished and significantly attenuated, respectively, the effects of kappa -OR stimulation on pH(i), [Na(+)](i)and [Ca(2+)](i), and arrhythmia. To determine the role of pH(i), we observed U50,488H-induced arrhythmia at pH(i)6.8. At this pH(i), the pH(i)increased gradually both in the presence and absence of 40 microm U50,488H to a similar extent. While the increase in response to U50,488H was significantly less at pH(i)6.8 (from 0.09 to 0.10) than that at pH(i)7.1 (from 0.01 to 0.18), the arrhythmia induced by the agonist was the same at both high and low pHs. On the other hand, 5 microm monensin, a sodium ionophore, increased [Na(+)](i)and [Ca(2+)](i), and induced arrhythmia to similar extents as U50,488H. PKC and NHE inhibitors, that significantly attenuated the effects induced by U50,488H, had no effect on those induced by monensin. In conclusion, kappa -OR stimulation induces arrhythmia via PKC/NHE. [Na(+)](i)and [Ca(2+)](i), but not pH(i), may be directly responsible for arrhythmia induced by kappa -OR stimulation.

Enhanced responses to 17beta-estradiol in rat hearts treated with isoproterenol: involvement of a cyclic AMP-dependent pathway

We determined the effects of 17beta-estradiol, the most effective estrogen, acutely administered, on the heart/ventricular myocyte with or without treatment with isoproterenol (Iso). At 0.1 to 1 nM, 17beta-estradiol, which itself had no effect, reduced the heart rate and developed pressures in the isolated perfused heart treated with 10(-7) M Iso. One nanomolar 17beta-estradiol also inhibited the cyclic AMP (cAMP) production in Iso-treated ventricular myocytes. At 10 nM to 1 microM, 17beta-estradiol itself reduced the heart rate and incidence of ischemia/reperfusion-induced arrhythmias, with the exception of diastolic pressure. The effects of 17beta-estradiol on heart rate, systolic and mean pressures, and arrhythmias were significantly enhanced in the heart/ventricular myocyte treated with Iso. Tamoxifen, an estrogen receptor antagonist, did not antagonize the effect of 17beta-estradiol on the Ca(2+) current in ventricular myocytes treated with Iso, nor did it alter the effect of the hormone on the cAMP production augmented by Iso and forskolin. The effects of 17beta-estradiol on Ca(2+) current in the presence or absence of tamoxifen and/or Iso were similar in male rats, which do not possess the estrogen receptor, and female rats, which have the estrogen receptor. In conclusion, we have shown for the first time that estrogen at physiological concentrations modulates negatively the stimulatory actions of Iso on the heart rate and cardiac contractility. The effects may result from activation of an unknown membrane receptor and the adenylate cyclase/cAMP pathway, which enhances Ca(2+) influx across the L-type Ca(2+) channel.

The role of phosphodiesterase in mediating the effect of protein kinase C on cyclic AMP accumulation upon kappa-opioid receptor stimulation in the rat heart

This study determined whether phosphodiesterase (PDE) was activated by protein kinase C (PKC) upon kappa-receptor stimulation, and if so, to identify the isozyme. We first studied the effects of trans-(+/-)-3,4-dichloro-N-methyl-N-(2-[1-pyrrolidinyl] cyclohexyl) benzeneacetamide methanesulphonate (U50,488H), a selective kappa-opioid receptor (OR) agonist, and phorbol-12-myristate-13-acetate (PMA), a PKC activator, on cAMP accumulation and PDE activity in rat ventricular myocytes when PKC and PDE were inhibited by respective inhibitors. Like PMA, U50,488H decreased the forskolin-stimulated cAMP accumulation and dose-dependently stimulated the PDE activity, which were antagonized by 10(-6) M chelerythrine and bisindolylmaleimide I, selective PKC antagonists. In addition, 3-isobutyl-1-methylxanthine, a PDE inhibitor, dose-dependently attenuated the inhibition on forskolin-stimulated cAMP accumulation and abolished the stimulation on PDE activity by U50,488H and PMA. The observations suggest that PKC may enhance cAMP degradation through activating PDE upon kappa-OR stimulation. To identify the isozyme(s) mediating the effect of PKC upon kappa-OR stimulation, selective inhibitors were used. We found that 10(-5) M Ro-20-1724, a selective cAMP-specific PDE (PDE-IV) inhibitor, abolished the inhibitory effects of U50,488H and PMA, whereas 8-methoxymethyl-3-isobutyl-1-methylxanthine, erythro-9-(2-hydroxy-3-nonyl) adenine, cilostamide, and zaprinast, selective inhibitors of Ca(2+)/calmodulin-dependent PDE (PDE-I), cGMP-stimulated PDE (PDE-II), cGMP-inhibited PDE (PDE-III), and cGMP-specific PDE (PDE-V), respectively, had no effect. Moreover, rolipram, another selective PDE-IV inhibitor, also dose-dependently attenuated the inhibition on forskolin-stimulated cAMP accumulation and stimulation on PDE activity by U50,488H and PMA. In conclusion, this study has provided evidence for the first time that PKC and PDE-IV mediate the action of kappa-OR.

HYAL1LUCA-1, a candidate tumor suppressor gene on chromosome 3p21.3, is inactivated in head and neck squamous cell carcinomas by aberrant splicing of pre-mRNA

The hyaluronidase first isolated from human plasma, Hyal-1, is expressed in many somatic tissues. The Hyal-1 gene, HYAL1, also known as LUCA-1, maps to chromosome 3p21.3 within a candidate tumor suppressor gene locus defined by homozygous deletions and by functional tumor suppressor activity. Hemizygosity in this region occurs in many malignancies, including squamous cell carcinomas of the head and neck. We have investigated whether cell lines derived from such malignancies expressed Hyal-1 activity, using normal human keratinocytes as controls. Hyal-1 enzyme activity and protein were absent or markedly reduced in six of seven carcinoma cell lines examined. Comparative genomic and fluorescence in situ hybridization identified chromosomal deletions of one allele of HYAL1 in six of seven cell lines. Initial RT - PCR analyses demonstrated marked discrepancies between levels of HYAL1 mRNA and protein. Despite repeated sequence analyses, no mutations were found. However, two species of transcripts were identified when primers were used that included the 5' untranslated region. The predominant mRNA species did not correlate with protein translation and contained a retained intron. A second spliced form lacking this intron was found only in cell lines that produced Hyal-1 protein. Inactivation of HYAL1 in these tumor lines is a result of incomplete splicing of its pre-mRNA that appears to be epigenetic in nature. Oncogene (2000) 19, 870 - 877.

Hemorrhagic pyelitis, ureteritis, and cystitis secondary to cyclophosphamide: case report and review of the literature

OBJECTIVE

Hemorrhagic cystitis is a well-known complication of cyclophosphamide therapy but extensive involvement of the entire urinary tract is far less common. We report here a patient who developed severe hemorrhagic pyelitis, ureteritis, and cystitis after one cycle of cyclophosphamide-containing combination chemotherapy.

METHOD

A patient with synchronous carcinoma of the ovary and the uterus developed severe hemorrhagic pyelitis, ureteritis, and cystitis leading to bilateral hydronephroses and acute renal failure after one cycle of combination chemotherapy containing cyclophosphamide. The blood clots in the upper urinary tract were aspirated endoscopically and bilateral internal ureteric stents were inserted.

RESULT

She underwent a prolonged diuretic phase with several episodes of hypokalemia, hypomagnesemia, and hypocalcemia and required intensive fluid and electrolytes replacement. Subsequently, she recovered fully with the ureteric stents removed 26 days later.

CONCLUSION

In contrast to previous reports, where 2.8 g of cyclophosphamide was estimated to be the minimum cumulative dose required to cause hemorrhagic cystitis, this case illustrates that severe hemorrhagic complication can occur even after a low dose of cyclophosphamide (600 mg/m(2), total dose of 846 mg). Prompt diagnosis and intervention may be life-saving.

Cognitive and behavioural efficacy of amantadine in acute traumatic brain injury: an initial double-blind placebo-controlled study

The objective of the current study was to determine the efficacy of amantadine in improving cognitive and behavioural performance in a traumatic brain injury (TBI) rehabilitation sample. The design was a prospective, randomized, double-blind, placebo-controlled, crossover design. Subjects were 10 adult traumatic brain injury patients in an acute brain injury rehabilitation unit. Subjects received a 2-week trail of amantadine or placebo, followed by a 2-week washout, then a 2-week trail of the alternative (placebo or amantadine). Neuropsychological outcome measures included orientation, attention, executive function, memory, orientation, behaviour, and a composite variable. Results of repeated measures ANOVA and regression analysis of slope/change showed a main effect of time, but no significant difference for amantadine versus placebo. In conclusion, although patients generally improved, this initial exploratory study found no differences in rate of cognitive improvement between subjects given amantadine versus those given placebo. However, the small sample size, heterogeneous population, acute time course, and large number of dependent variables limit power and generalizability. Implications are discussed for further research to better answer questions regarding efficacy of amantadine post-TBI.

Pro- and anti-arrhythmic effects of a kappa opioid receptor agonist: a model for the biphasic action of a local hormone in the heart

1. The effects of kappa opioid receptor stimulation on cardiac rhythm and the underlying signal pathways were investigated in the rat. 2. Stimulation of kappa opioid receptors with 40-50 mumol/L U50 488H, a selective kappa opioid receptor agonist, induced dysrhythmias and increased inositol 1,4,5-trisphosphate (IP3) production in rat isolated, perfused heart. The pro-arrhythmic effects of U50 488H were abolished by 5 mumol/L norbinaltorphimine (nor-BNI), a specific kappa opioid receptor antagonist. 3. The effect of U50 488H on cardiac dysrhythmia and IP3 production were abolished by 1 mmol/L neomycin and streptomycin, phospholipase C (PLC) inhibitors. 4. At 1 mumol/L, U50 488H, which itself has no effect on cardiac rhythm and IP3 production, significantly attenuated the potentiating effect of 1 mumol/L noradrenaline (NA) on dysrhythmias, which were induced by low flow in the isolated heart. The effects of U50 488H were abolished by 1 mumol/L nor-BNI. Cytosolic cAMP production was augmented by 1 mumol/L NA and this was significantly attenuated by 1 mumol/L U50 488H. 5. At 1 mumol/L, U50 488H also reduced [Ca2+]i oscillations induced by 0.5 mumol/L NA and 0.5 mumol/L forskolin, an activator of adenylate cyclase (AC). 6. In conclusion, U50 488H exerted pro- and anti-arrhythmic actions at high and lower concentrations, respectively. The former effect was mediated via the PLC/IP3 pathway, while the latter was mediated via the AC/cAMP pathway.

Anti-arrhythmic effect of kappa-opioid receptor stimulation in the perfused rat heart: involvement of a cAMP-dependent pathway

During myocardial ischaemia the beta-adrenoceptor is activated, which contributes, at least partly, to cardiac arrhythmias via inducing [Ca2+]i oscillations. Since beta-adrenoceptor is negatively modulated by the kappa-opioid receptor in the heart, the present study attempted to determine if kappa-opioid receptor stimulation modulates the arrhythmogenic action of beta-adrenoceptor stimulation and to delineate the underlying mechanism. The effect of U50,488H, a selective kappa-opioid agonist, on arrhythmias in the isolated perfused rat heart subjected to low flow and 10(-6)mol/l norepinephrine (NE) were determined. Low flow induced arrhythmias, which were potentiated by NE, but not by 10(-6)mol/l U50,488H. The arrhythmia-potentiating effect of NE was antagonized by 10(-6)mol/l propranolol, a beta-adrenoceptor antagonist. U50,488H at 10(-6)mol/l also abolished the potentiation in arrhythmias by NE without affecting the arrhythmias induced by low flow. The anti-arrhythmic action of the kappa-opioid receptor agonist was abolished by 10(-6)mol/l nor-binaltorphimine, a selective kappa-opioid receptor antagonist, but not by 10(-7)mol/l calphostin C, an inhibitor of protein kinase C. Similarly, kappa-opioid receptor stimulation with U50,488H also abolished the NE-induced [Ca2+]i oscillations which are believed to cause cardiac arrhythmias, in ventricular myocytes. To determine whether the inhibitory actions of U50,488H against the effects of beta-adrenoceptor stimulation was via a cAMP-dependent or a cAMP-independent pathway, we determined the effects of U50,488H on NE-enhanced cAMP production and [Ca2+]i oscillations induced by either forskolin, an activator of adenylate cyclase, or Bay K-8644, a selective L-type Ca2+ channel agonist, in the ventricular myocytes. We found that U50,488H abolished the effect of forskolin, but did not alter the effect of Bay K-8644, on [Ca2+]i oscillations in the ventricular myocyte. In addition, U50, 488H also attenuated significantly the NE-induced elevation in cAMP in the heart. The observations suggest that kappa-opioid receptor stimulation abolishes the effect of beta-adrenoceptor stimulation on arrhythmias and [Ca2+]i oscillation via a cAMP-dependent pathway. The finding may be useful for the prevention and treatment of ischaemic heart diseases.

Electrically induced intracellular Ca2+ transient in single ventricular myocytes: a useful parameter for the study of cardiac drugs

1. Fluorescent Ca2+ indicators, such as fura-2/AM and calcium green-1, have become one of the most popular tools for measuring intracellular calcium ([Ca2+]i). 2. Electrical stimulation triggers a cascade of events in the cardiac muscle, which results in a [Ca2+]i transient and, eventually, contraction. The events that occur in electrically induced cardiac myocytes mimic the normal physiological events in vivo. 3. The electrically induced [Ca2+]i transient represents influx of Ca2+ from outside and mobilization of Ca2+ from the intracellular store and is directly related to contraction. Thus, it is more important to determine the electrically induced [Ca2+]i transient than [Ca2+]i. The [Ca2+]i transient can be easily measured with the spectrofluorescence method using fura 2/AM as the Ca2+ indicator in a single ventricular myocyte preparation. 4. We made use of the results of studies on carbachol, tetrandrine and cardiotoxin to illustrate the usefulness of the electrically induced [Ca2+]i transient in the study of actions of cardiac drugs.

Acidosis antagonizes intracellular calcium response to kappa-opioid receptor stimulation in the rat heart

To study the effects of kappa-opioid receptor stimulation on intracellular Ca2+ concentration ([Ca2+]i) homeostasis during extracellular acidosis, we determined the effects of kappa-opioid receptor stimulation on [Ca2+]i responses during extracellular acidosis in isolated single rat ventricular myocytes, by a spectrofluorometric method. U-50488H (10-30 microM), a selective kappa-opioid receptor agonist, dose dependently decreased the electrically induced [Ca2+]i transient, which results from the influx of Ca2+ and the subsequent mobilization of Ca2+ from the sarcoplasmic reticulum (SR). U-50488H (30 microM) also increased the resting [Ca2+]i and inhibited the [Ca2+]i transient induced by caffeine, which mobilizes Ca2+ from the SR, indicating that the effects of the kappa-opioid receptor agonist involved mobilization of Ca2+ from its intracellular pool into the cytoplasm. The Ca2+ responses to 30 microM U-50488H were abolished by 5 microM nor-binaltorphimine, a selective kappa-opioid receptor antagonist, indicating that the event was mediated by the kappa-opioid receptor. The effects of the agonist on [Ca2+]i and the electrically induced [Ca2+]i transient were significantly attenuated when the extracellular pH (pHe) was lowered to 6.8, which itself reduced intracellular pH (pHi) and increased [Ca2+]i. The inhibitory effects of U-50488H were restored during extracellular acidosis in the presence of 10 microM ethylisopropyl amiloride, a potent Na+/H+ exchange blocker, or 0.2 mM Ni2+, a putative Na+/Ca2+ exchange blocker. The observations indicate that acidosis may antagonize the effects of kappa-opioid receptor stimulation via Na+/H+ and Na+/Ca2+ exchanges. When glucose at 50 mM, known to activate the Na+/H+ exchange, was added, both the resting [Ca2+]i and pHi increased. Interestingly, the effects of U-50488H on [Ca2+]i and the electrically induced [Ca2+]i transient during superfusion with glucose were significantly attenuated; this mimicked the responses during extracellular acidosis. When a high-Ca2+ (3 mM) solution was superfused, the resting [Ca2+]i increased; the increase was abolished by 0.2 mM Ni2+, but the pHi remained unchanged. Like the responses to superfusion with high-concentration glucose and extracellular acidosis, the responses of the [Ca2+]i and electrically induced [Ca2+]i transients to 30 microM U-50488H were also significantly attenuated. Results from the present study demonstrated for the first time that extracellular acidosis antagonizes the effects of kappa-opioid receptor stimulation on the mobilization of Ca2+ from SR. Activation of both Na+/H+ and Na+/Ca2+ exchanges, leading to an elevation of [Ca2+]i, may be responsible for the antagonistic action of extracellular acidosis against kappa-opioid receptor stimulation.

Cardioprotection of preconditioning by metabolic inhibition in the rat ventricular myocyte. Involvement of kappa-opioid receptor

To determine whether opioid receptors (ORs) are involved in the delayed cardioprotection of ischemic preconditioning (IP), the effect of severe metabolic inhibition (MI) with a glucose-free buffer that contained sodium cyanide and 2-deoxy-D-glucose on the viability of isolated rat ventricular myocytes was first determined 20 hours after preconditioning with a sublethal metabolic inhibition (MIP) with a glucose-free buffer that contained 2-deoxy-D-glucose and lactate for 30 minutes in the presence of OR antagonists. With the use of trypan blue exclusion as an index of cell viability, severe MI killed >60% of the cells and the value increased significantly after MIP. In the presence of 5x10(-6) mol/L nor-binaltorphimine (nor-BNI), a selective kappa-OR antagonist, but not 5x10(-6) mol/L CTOP, a selective mu-OR antagonist, or 5x10(-6) mol/L naltrindole, a selective delta-OR antagonist, the cardioprotection of MIP was significantly attenuated. To verify the role of kappa-OR, we studied the effects of severe MI after pretreatment with the kappa-OR agonist U50,488H (UP) for 30 minutes. U50,488H at 3x10(-6) to 1x10(-4) mol/L increased cell viability concentration-dependently with an EC50 of 3.311x10(-6) mol/L. In the presence of 5x10(-6) nor-BNI, the cardioprotection of UP (3x10(-5) mol/L) was blocked. A time course study showed that UP-induced cardioprotection occurred in 2 windows: the first occurred approximately 1 hour later and the other occurred 16 to 20 hours later. Additional studies on cell contraction and intracellular Ca2+ ([Ca2+]i) revealed that both UP and MIP attenuated the inhibitory effects of severe MI on contractility and electrically induced [Ca2+]i transient in single ventricular myocytes. On blockade of protein kinase C, the delayed cardioprotections of UP and MIP were significantly attenuated. In conclusion, the results of the present study have provided evidence that kappa-OR mediates the cardioprotection of MIP, which may involve protein kinase C and [Ca2+]i.

Cross-talk between cardiac kappa-opioid and beta-adrenergic receptors in developing hypertensive rats

The kappa-opioid receptor exerts a negative modulatory action on the beta-adrenoceptor and the action is blunted in adult spontaneously hypertensive rats (SHR). In order to determine whether the blunted negative modulation of the beta-adrenoceptor by the kappa-opioid receptor contributes to the development of hypertension, the electrically induced intracellular calcium ([Ca2+]i) transient was measured in single ventricular myocytes of SHR at 4, 6, 8 and 13-week-old and the age-matched Wistar Kyoto (WKY) rats. The electrically induced [Ca2+]i transients were augmented by norepinephrine (NE), a beta-adrenoceptor agonist, over four-fold in WKY rats of all ages studied and in SHR of 4 and 6 weeks of age. The enhancing effect of NE in 8- and 13-week-old SHR was, however, only approximately three-fold, significantly lower than the corresponding values in age-matched WKY rats. Similarly, the electrically induced [Ca2+]i transients were also augmented by forskolin, an activator of adenylate cyclase, by approximately two-fold in WKY rats of all ages and SHR aged 4 and 6 weeks. In SHR aged 8 and 13 weeks, the effect of forskolin was only 1.5-fold, significantly lower than the two-fold increase in the corresponding WKY rats. The enhancing effects of NE and forskolin were attenuated by U50,488H, a selective kappa-opioid agonist, by approximately 50 and 25%, respectively, in both types of rats of all ages studied, with the exception of 13-week-old rats. In rats of this age group, the attenuations by U50,488H on the enhancing effects of NE and forskolin were 17 and 9% in SHR, respectively, significantly less than the corresponding 54 and 29% in WKY. The fact that attenuation of U50,488H on the enhancing effects of NE and forskolin only occurs in 13-week-old SHR when hypertension has been fully developed indicates that the attenuated inhibitory modulation of kappa-opioid receptor stimulation does not contribute to the initiation of hypertension. Interestingly, the enhancing effects of NE and forskolin on the electrically induced [Ca2+]i transient was attenuated in SHR aged from 8 weeks when the blood pressure was rapidly increasing. The different time courses of altered responses to U50,488H, and NE and forskolin suggest that the attenuated negative modulation of kappa-receptor stimulation on the beta-adrenergic receptor is not due to the signal transduction pathway activated by beta-adrenergic stimulation. In 13-week-old SHR with the arterial blood pressure restored to normal by pharmacological manipulations, the blunted responses to NE, U50,488H and forskolin still occurred, indicating that the altered responses to activation of beta-adrenergic and kappa-opioid receptors and adenylate cyclase are not secondary to hypertension.

Effects of U50488 and bremazocine on [Ca2+]i and cAMP in naive and tolerant rat ventricular myocytes: evidence of kappa opioid receptor multiplicity in the heart

To explore the existence of multiplicity of kappa receptor in the heart, two series of experiments were performed. In the first we studied the antagonistic actions of nor-BNI, a selective kappa 1 antagonist, and quadazocine, a preferential kappa 2 antagonist, against the effects of U50488, a selective kappa 1 agonist, and bremazocine, a universal agonist preferentially binding to kappa 2 receptor, on the electrically stimulated [Ca2+]i transient and forskolin-stimulated cAMP accumulation in the rat ventricular myocyte. In the second series of experiments, we determined and compared the effects of above two kappa receptor agonists in the ventricular myocytes made insensitive to kappa 1 and kappa 2 agonists by prior exposure to the respective agonists. At the concentration range of 3 x 10(-6)-3 x 10(-5) M, both U50488 and bremazocine dose-dependently inhibited the [Ca2+]i transient induced by electrical stimulation. The inhibitory effects of U50488 and bremazocine were antagonized by nor-BNI and quadazocine. The antagonistic actions of nor-BNI were significantly greater against the effects of U50488, but smaller against the effects of bremazocine than those of quadazocine. At 1 x 10(-6)-5 x 10(-5) M, both U50488 and bremazocine dose-dependently and significantly inhibited the forskolin-induced cAMP accumulation. The inhibitory effect of 30 microM U50488 on cAMP accumulation was significantly attenuated by 5 microM nor-BNI, but not by quadazocine at the same concentration; whereas the effect of 30 microM bremazocine was significantly blocked by 5 microM quadazocine, but not by nor-BNI at the same concentration. The inhibitory effect of 30 microM U50488 on electrically stimulated [Ca2+]i was abolished by preincubation of myocytes with 10(-6) M U50488 for 24 h, but not with 10(-6) M bremazocine for h; whereas the inhibitory effect of 30 microM bremazocine on electrically stimulated [Ca2+]i transient was significantly attenuated after incubation of the myocyte with 10(-6) M bremazocine for 24 h, but not with 10(-6) M U50488 for 24 h. The observations indicate the existence of kappa receptor subtypes in the rat heart.

Spontaneous activity and barosensitivity of the barosensitive neurons in the rostral ventrolateral medulla of hypertensive rats induced by transection of aortic depressor nerves

In order to determine the role of the rostral ventrolateral medulla (RVLM) in the development of neurogenic hypertension, the aortic depressor nerves of rats were transected (tADN) to produce neurogenic hypertension. The rate and pattern of firing of the barosensitive RVLM neurons of the treated rats were studied. In neurogenic hypertensive rats, the RVLM barosensitive neurons exhibited a faster firing rate and a shorter interspike interval (ISI) than the corresponding values of the control and sham groups, indicating an enhanced spontaneous activity of these neurons in the hypertensive rats. The coefficient of variation (cv) and skewness (sk) of the ISI histogram, parameters reflecting the regularity of neuronal firing, were smaller in neurogenic hypertensive than in the control and sham-operated rats. Following tADN, the responsiveness of these neurons to blood pressure changes was attenuated, suggesting a reduced intrinsic barosensitivity of neurons and/or a reduced baroreceptor input. The increase in spontaneous activity and firing regularity of RVLM barosensitive neurons imply an enhancement in the efficacy of outflow from these neurons. The increased efficacy of the outflow from the RVLM barosensitive neurons and the resetting of the baroreflex may contribute to the genesis of neurogenic hypertension.

[Involvement of endogenous opioids in cardioprotective effects of ischemic preconditioning in the isolated rat heart]

In the present study, the relationship between the blockade of kappa-opioid receptor and ischemic preconditioning (IP) was examined and the effect of IP and prolonged ischemia on levels of dynorphin A1-13 (Dyn A1-13) in cardiac muscle in isolated perfused rat heart was investigated. The results are as follows: (1) IP reduced the severity of ischemia/reperfusion arrhythmia (P < 0.05) and infarct size (P < 0.01), but had no significant effect on heart rate and coronary flow (P > 0.05); (2) MR2266, kappa opioid receptor antagonist, reduced the severity of ischemia/reperfusion arrhythmia (P < 0.05) and infarct size (P < 0.01), and also enhanced the recovery of coronary flow, but had no significant effect on heart rate (P > 0.05); and (3) prolonged ischemia decreased the levels of Dyn A1-13 (P < 0.05), which was more marked in the unpreconditioned hearts. The results suggest: (1) MR2266 can "mimic" cardioprotective effect of IP in reducing the severity of arrhythmias and limiting infarct size of cardiac muscle; (2) ischemia causes release of endogenous kappa opioids, which can be attenuated by IP; and (3) the cardioprotective effects of IP in rat heart involves endogenous kappa opioids.

Phospholipase C inhibitors attenuate arrhythmias induced by kappa-receptor stimulation in the isolated rat heart

To determine whether the phospholipase C (PLC)/inositol 1,4,5 trisphosphate (IP3)/Ca2+ pathway mediates cardiac arrhythmias induced by kappa-opioid receptor stimulation, the effects of U50,488H, a selective kappa-opioid receptor agonist, on cardiac rhythm in a isolated perfused rat heart, intracellular calcium ([Ca2+]i) in a single ventricular myocyte and IP3 production in myocytes were studied in the presence and absence of PLC inhibitors. U50,488H, the effects of which had been shown to be abolished by a selective kappa-receptor antagonist, nor-binaltorphimine, induced arrhythmias dose-dependently and increased both [Ca2+]i and IP3-production in the heart. More importantly, the effects of U50,488H were blocked by PLC inhibitors, neomycin and streptomycin. To further confirm the selectivity of action of the PLC inhibitor, the effects of another PLC inhibitor U73122 and its inactive structural analog, U73343, on cardiac rhythm in the isolated perfused rat heart were compared. The former did, while the latter did not, block the arrhythmogenic effect of U50,488H. We also determined whether the effects of kappa-receptor stimulation involves a pertussis toxin (PTX)-sensitive G-protein. We found that pretreatment with PTX at 4 microg/l for 10 min, a treatment shown to affect PTX sensitive G-protein-mediated functions, attenuated significantly the U50,488H-induced arrhythmias. The present study provides evidence that kappa-receptor stimulation-induced cardiac arrhythmias involves, at least partly, the PLC/IP3/Ca2+ pathway as well as a PTX sensitive G-protein.

Continuous nebulization therapy for asthma with aerosols of beta2 agonists

BACKGROUND

Various studies have demonstrated the benefits of continuous nebulization therapy for delivering aerosols of the beta2 agonists such as terbutaline sulfate or albuterol sulfate to patients with severe asthma and/or impending respiratory failure.

OBJECTIVE

The purpose of this investigation was to explicate the operational factors associated with the use of nebulizers for extended aerosol respiratory therapy including those factors that affect the prescribed aerosol dosages and the relationship to actual delivery of prescribed drugs to the respiratory airways of the lungs of a patient under treatment conditions.

METHODS

Operational characteristics and methods have been investigated for use of long-running nebulizers for continuous nebulization therapy. Factors considered were particle size distribution, setup conditions, aerosolization concentrations and rates, delivery fraction of aerosol reaching patient, and changes in medication concentration during extended operation. With a large volume nebulizer, aerosols can be delivered to the patient without dilution via a standard open mask for up to eight hours without refill. The pneumatic HEART nebulizer with 240 mL reservoir was evaluated.

RESULTS

The nebulizer was operated from a single compressed air or oxygen source and found to provide from 10 to 15 L/min of aerosol with 38 to 50 microL of aerosolized medicine per liter of air (or oxygen) and utilize from 30 to 56 mL/hour of medicinal liquid. The mass median aerodynamic diameter of the aerosol droplets was found to be about 2.0 microm (sigma(g) = 2.7). Delivery efficiency to the patient mask was about 90%. The aerosolized medicine delivered to the patient can be increased by adjusting the flow rate of the gas source or changing the solution concentration of medicine. Typically, several milligrams of drug can be delivered to the patient as inhaled aerosol per hour of treatment of which about one-quarter can be expected to be deposited in the lungs. During eight hours of operation the concentration of medicinal solution increased by about a factor of two because of water evaporation.

CONCLUSIONS

Continuous nebulization therapy is an important means of treating patients with severe asthma. Dosage criteria can be established based on the operating characteristics of the nebulizer system, drug solution concentration, and patient respiration.