Diseases associated with altered ryanodine receptor activity

Mutations in two intracellular Ca2+ release channels or ryanodine receptors (RyR1 and RyR2) are associated with a number of human skeletal and cardiac diseases. This chapter discusses these diseases in terms of known mechanisms, controversies, and unanswered questions. We also compare the cardiac and skeletal muscle diseases to explore common mechanisms.

Effect of treatment on myocardial performance index (MPI) in chronic severe anaemia

Anaemia is a common ailment in developing countries which imposes mechanical load on heart. Myocardial Performance index (MPI) was evaluated by apex cardiogram (ACG) in 30 patients suffering from chronic severe anaemia (CSA) (with hemoglobin level less than 6 gm% and at least more than 3 months duration) before and after treatment in the age group of 20-40 years and compared with age and sex matched healthy controls. MPI was measured by simultaneous recordings of apex cardiogram, carotid arterial pulse, electrocardiogram and phonocardiogram on four channel polyrite (INCO). There was considerable increase (P<0.001) in heart rate (HR), left ventricular ejection time (ET) (P<0.02), shortening of isovolumic contraction time (ICT) (P<0.001), with no significant change in isovolumic relaxation time (IVRT) in anaemia versus controls. On treatment of anaemia HR and ET decreases (P<0.001), ICT increases (P<0.01) without any change in IVRT. Our findings indicate that performance of myocardium is improved after treatment. So treatment should be instituted as early as possible.

Neuroaspergillosis in an immunocompetent patient

Aspergillosis of the central nervous system (CNS) is an uncommon infection, mainly occurring in immunocompromised patients. We report a case of neuroaspergillosis caused by Aspergillus flavus in an immunocompetent patient presenting as a space-occupying lesion of the CNS. The patient was responding favorably to voriconazole at the time of this report.

Effect of Ocimum sanctum Linn. on cardiac changes in rats subjected to chronic restraint stress

Male Wistar rats were subjected to chronic restraint stress (CRS; 6 h/day for 21 days) alone or along with either hydroalcoholic extract of Ocimum sanctum (Os; 100 mg/kg; orally) or MK-801, an NMDA receptor antagonist (0.3 mg/kg; i.p.). In the rats subjected to only CRS, plasma cAMP level was significantly raised on day 21, with no significant change in plasma corticosterone level. There was a significant (p < 0.05) fall in myocardial glutathione level, along with a significant (p < 0.05) rise in myocardial superoxide dismutase (SOD) and catalase activities, while light microscopy showed evidence of myocardial edema. Both Os and MK-801 significantly prevented the CRS-induced rise in plasma cAMP level, myocardial SOD and catalase activities as well as the light microscopic changes in the myocardium. This study revealed that Ocimum sanctum protects rat heart from chronic restraint stress induced changes, through its central effect.

Role of CT angiography in pulmonary embolism and its comparative evaluation with conventional pulmonary angiography

OBJECTIVES : The purpose of this study is to assess the role of spiral CT angiography in suspected cases of pulmonary embolism and to do comparative evaluation of CT angiography with conventional pulmonary angiography. MATERIAL AND METHODS : Twenty five patients of suspected pulmonary embolism (PE) underwent spiral CT angiography from the level of arch of aorta to the dome of diaphragm .Scanning was done with collimation of 5mm and an interval of 5mm at 130 mA and 120 kV. 100 cc of contrast containing 300 mg I/ ml, diluted with 60cc of normal saline in ratio 5:3 was injected at a flow rate of 3ml/sec with a scan delay of 20 seconds. Retro - reconstruction was done at 3mm interval. RESULTS : Spiral CTA showed a sensitivity of 80 % and a specificity of 85.7% for the diagnosis of pulmonary embolism. It also provided ancillary findings in the form of parenchymal and mediastinal structural information. CONCLUSION : CTA is an effective alternative to PA in diagnosis of suspected cases of PE. With its non- invasive nature, low cost, over and above high sensitivity and specificity, it may be used as the first line of investigation in the diagnosis of PE.

The effects of esomeprazole combined with aspirin or rofecoxib on prostaglandin E2 production in patients with Barrett's oesophagus

BACKGROUND

Reducing mucosal cyclo-oxygenase-2 and prostaglandin E(2) production and suppressing intraoesophageal acid may be effective chemopreventive strategies in patients with Barrett's oesophagus.

AIM

To compare the effects of aspirin and rofecoxib when administered with esomeprazole on prostaglandin E(2) production, cyclo-oxygenase-2 expression and proliferating cell nuclear antigen expression in patients with Barrett's oesophagus.

METHODS

This exploratory, multicentre, randomized, open-label, four-way crossover study in 45 patients with Barrett's oesophagus evaluated prostaglandin E(2) content, proliferating cell nuclear antigen expression, and cyclo-oxygenase-2 expression after 10 days of sequential treatments with: esomeprazole 40 mg twice daily plus aspirin 325 mg once daily (E40 b.d. + A325); E40 b.d. plus rofecoxib 25 mg once daily (E40 b.d. + R25); E40 b.d.; and rofecoxib 25 mg once daily (R25).

RESULTS

Prostaglandin E(2) content reduction in Barrett's oesophagus tissue was significantly greater with E40 b.d. + A325 compared with E40 b.d. + R25, E40 b.d. or R25 (P < 0.05). All treatments containing E40 b.d. significantly decreased proliferating cell nuclear antigen expression from baseline (P < 0.05). None of the treatments significantly reduced cyclo-oxygenase-2 expression.

CONCLUSIONS

The combined treatment of esomeprazole 40 mg b.d. and aspirin 325 mg significantly decreased mucosal prostaglandin E(2) content and all treatments containing esomeprazole significantly reduced proliferating cell nuclear antigen expression in patients with Barrett's oesophagus.

Urinary tract infection byTrichosporon asahii

Trichosporon asahii is a basidiomycetous yeast which causes white piedra and onychomycosis in immunocompetent hosts as well as various localized and disseminated invasive infections in immunodeficient hosts. Urinary tract infection caused by Trichosporon asahii is rare. One month after posterior urethral valve surgery a seven-month-old male child presented with fever, severe vomiting and crying on micturition for five--to six days. Yeast-like fungus was isolated in pure cultures from three consecutive urine samples. It was identified as Trichosporon asahii using standard techniques. The response to antifungal therapy was dramatic. To the best of our knowledge this is the first report of a urinary tract infection caused by Trichosporon asahii from Western India.

Respiratory activation of the genioglossus muscle involves both non-NMDA and NMDA glutamate receptors at the hypoglossal motor nucleus in vivo

Brainstem respiratory neurons innervate the hypoglossal motor nucleus which in turn transmits this respiratory drive signal to the genioglossus muscle of the tongue. The mechanism of this transmission is important to help maintain an open airspace for effective breathing, and is thought to rely almost exclusively on non-N-methyl-d-aspartate (non-NMDA) glutamate receptor activation during respiration. However those studies were performed in slices of medulla from neonatal animals in vitro which may have led to an underestimation of the contribution of NMDA glutamate receptors that may normally operate in intact preparations. The current study tests the hypothesis that both NMDA and non-NMDA receptors contribute to respiratory drive transmission at the hypoglossal motor nucleus in vivo. Experiments were performed in urethane-anesthetized and tracheotomized adult Wistar rats in which vagus nerves were either intact or sectioned. In the presence of augmented genioglossus activity produced by vagotomy, microdialysis perfusion of either an NMDA receptor antagonist (D-2-amino-5-phosphonovaleric acid, 0.001-10 mM) or a non-NMDA receptor antagonist (6-cyano-7-nitroquinoxaline-2, 3-dione disodium salt, 0.001-1 mM) to the hypoglossal motor nucleus reduced respiratory-related genioglossus activity in a dose-dependent manner (P < 0.001) indicating that both NMDA and non-NMDA glutamate receptors are necessary for transmission of the respiratory drive signal to genioglossus muscle in vivo. Similar effects were observed in the vagus nerve intact rats. Further experiments demonstrated that each delivered antagonist had effects that were specific to its respective receptor. Regression analysis also revealed that the activity of both NMDA and non-NMDA receptors at the hypoglossal motor nucleus is related to levels of the prevailing respiratory drive. These results show that both NMDA and non-NMDA glutamate receptors at the hypoglossal motor nucleus are involved in transmission of the respiratory drive signal to genioglossus muscle in vivo.

Extract from Clerodendron colebrookianum Walp protects rat heart against oxidative stress induced by ischemic–reperfusion injury (IRI)

Reactive oxygen species (ROS) have pathogenic effects on ischemic-reperfusion injury of heart. Hence, it is important to identify natural antioxidative agents to mitigate such effects. Recently, it has been reported that Clerodendron colebrookianum (CC) leaf extract has antioxidant and hypolipidemic effects in experimental animals. The aim of this study was to examine whether acute treatment with CC extract offers protection against ischemic-reperfusion injury (IRI) and IRI-induced changes in endogenous antioxidant enzyme activities of rat heart. Isolated rat hearts were perfused using the Langendorff's technique, and 20 min of global ischemia was followed by 40 min of reperfusion. Lipid peroxidation after the ischemic-reperfusion episode was significantly reduced in the CC extract-treated heart compared to the control group and suppressed the leakage of lactate dehydrogenase (LDH) during reperfusion. Moreover, CC extract diminished the depletion of myocardial antioxidant enzymes (SOD, Catalase, GSH and GPx) after ischemia-reperfusion. Furthermore, IRI-induced cellular damage was significantly less in CC extract treated myocytes. These results indicate that CC leaf extract protects against oxidative stress and cellular injury associated with ischemic-reperfusion injury of rat heart and suggests that the protective effects of CC extract depend on its antioxidant properties.

Effect of adenotonsillitis on peak exploratory flow rate in children

Peak Exploratory Flow Rate (PEFR) is a simple, economical, reproducible, non-invasive test, which can be quickly performed with ease. PEFR was assessed in 36 children with adenotonsillar enlargement with mean age 10.75 years and equal number of age and sex matched normal children who acted as controls. PEFR was found to be 250. 61 +/- 66.92 lt/min in controls and 216.85 +/- 59.76 lt/min in children with adenotonsillar enlargement signifying impairment of PEFR in children in the second group.

Links between phytoplankton and bacterial community dynamics in a coastal marine environment

Bacteria and phytoplankton dynamics are thought to be closely linked in coastal marine environments, with correlations frequently observed between bacterial and phytoplankton biomass. In contrast, little is known about how these communities interact with each other at the species composition level. The purpose of the current study was to analyze bacterial community dynamics in a productive, coastal ecosystem and to determine whether they were related to phytoplankton community dynamics. Near-surface seawater samples were collected in February, May, July, and September 2000 from several stations in the Bay of Fundy. Savin et al. (M.C. Savin et al., Microb Ecol 48: 51-65) analyzed the phytoplankton community in simultaneously collected samples. The attached and free-living bacterial communities were collected by successive filtration onto 5 microm and 0.22 microm pore-size filters, respectively. DNA was extracted from filters and bacterial 16S rRNA gene fragments were amplified and analyzed by denaturing gradient gel electrophoresis (DGGE). DGGE revealed that diversity and temporal variability were lower in the free-living than the attached bacterial community. Both attached and free-living communities were dominated by members of the Roseobacter and Cytophaga groups. Correspondence analysis (CA) ordination diagrams showed similar patterns for the phytoplankton and attached bacterial communities, indicating that shifts in the species composition of these communities were linked. Similarly, canonical CA revealed that the diversity, abundance, and percentage of diatoms in the phytoplankton community accounted for a significant amount of the variability in the attached bacterial community composition. In contrast, ordination analyses did not reveal an association between free-living bacteria and phytoplankton. These results suggest that there are specific interactions between phytoplankton and the bacteria attached to them, and that these interactions influence the composition of both communities.

Effect of estrogen on hypoglycemia induced neurological impairment in ovariectomized rats

The risk of hypoglycemia and the resulting functional derangement of the brain are one of the major complications with stringently controlled diabetes mellitus. Ovarian steroid hormones, particularly estradiol, play a modulatory role in the ability of the female brain to utilize glucose. In the present study, the effects of estrogen on hypoglycemia-induced neurological impairment were done in ovariectomized rats. Animals received either vehicle or estradiol benzoate treatment. Hypoglycemia (Blood glucose levels <50 mg/dl) was induced in all the rats by insulin (2 U/kg, IP). Neurological functions were assessed using an 18 point scale at different time intervals of hypoglycemia. Estradiol benzoate (100 microg/kg IP) significantly (p<0.05) deteriorated the neurological functions in ovariectomized rats during hypoglycemia. The present study thus reveals that estradiol benzoate is responsible for further aggravation of neurological impairment induced by insulin hypoglycemia in female rats.

Current management in pharyngeal pouch surgery by UK otorhinolaryngologists

INTRODUCTION

Many surgical techniques have been described for the treatment of pharyngeal pouches but there is no single treatment of choice. The aim of this study was to determine current practice in pharyngeal pouch surgery by UK otolaryngologists.

METHODS

A postal questionnaire was sent to all UK-based consultant members of the British Association of Otolaryngologists - Head and Neck Surgeons (BAO-HNS).

RESULTS

Endoscopic stapling diverticulotomy is the most commonly performed procedure, performed by 89% of surgeons, followed by excision. Of those consultants that considered there to be a treatment of choice, 83% stated endoscopic stapling as their preference. Practices differ regarding the insertion of nasogastric tubes after endoscopic procedures and the need for postoperative barium studies. The length of in-patient stay tends to be short with 80% of surgeons discharging patients by day 2.

CONCLUSIONS

Endoscopic stapling diverticulotomy is now the most commonly performed procedure for the management of pharyngeal pouches by UK otolaryngologists and is now considered by many to be the treatment of choice.

Emblica officinalis causes myocardial adaptation and protects against oxidative stress in ischemic-reperfusion injury in rats

The fruits of Emblica officinalis (Amla) are widely used in the Indian System of Medicine and are believed to increase defense against disease. In the present study, the effects of chronic oral administration of fresh fruit homogenate of Amla on: (i). myocardial antioxidant system and (ii). oxidative stress induced by ischemic-reperfusion injury (IRI) in rat heart were investigated. Fresh amla fruit homogenate, in three different doses (250, 500 and 750 mg/kg) and normal saline (C) were administered orally to Wistar albino rats (120-150 gms) of either sex daily for 30 days. There was reduction in basal myocardial lipid peroxidation, as evidenced by decreased thiobarbituric acid reactive substances (TBARS) level, and augmentation of myocardial endogenous antioxidants, like superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) in the treated rats. Hearts were also subjected to in vitro IRI (9 min of global ischemia, followed by 12 min of reperfusion, Langendorff's mode). Significant myocyte injury and rise in myocardial TBARS along with depletion of SOD, catalase, GSH (reduced glutathione) and GPx occurred in the control group. No significant increase in myocardial TBARS and depletion of antioxidant enzymes were observed in the treated groups. Myocyte injury was evident only in 250 mg/kg group. The results indicate that chronic Emblica officinalis administration causes myocardial adaptation by augmenting endogenous antioxidants and protects rat hearts from oxidative stress associated with ischemic-reperfusion injury.

Chronic oral administration of raw garlic protects against isoproterenol-induced myocardial necrosis in rat

Wistar albino rats (150-200 g) were fed raw garlic homogenate orally in three different doses (125, 250, 500 mg/kg/day) for 30 days. Isoproterenol (85 mg/kg, s.c. 2 doses at 24-h interval, animals sacrificed after 24 h of last injection) induced myocardial necrosis in control rats and after 30 days of garlic feeding. Myocardial oxidative stress was evident following isoproterenol administration by reduction in myocardial superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities along with a rise in plasma thiobarbituric acid reactive substances (TBARS). Myocardial necrosis was evident from the light microscopic and ultrastructural changes, along with a rise in plasma lactate dehydrogenase (LDH). Significant preservation of myocardial SOD activity was observed in all the garlic-fed rats. However, there was no significant change in myocardial reduced glutathione level and GPx activity in any of the treated groups. Significant reduction in plasma TBARS and LDH levels was observed in the 500 mg/kg garlic treated group. Isoproterenol-induced myocardial morphological changes were least in the 250 and 500 mg/kg garlic treated groups. The results suggest that chronic oral administration of raw garlic offered protection against isoproterenol-induced myocardial necrosis and associated oxidative stress.

Rasmussen encephalitis associated with Parry-Romberg syndrome

Parry-Romberg syndrome is a rare disorder associated with unilateral facial atrophy involving skin, subcutaneous tissue, skeletal muscle, and bone. Occasionally, there is CNS involvement with epilepsy being the most common CNS manifestation. The authors report a child with Parry-Romberg syndrome with a course strongly suggestive of Rasmussen encephalitis. The boy underwent hemispherectomy, and pathology showed the typical findings of Rasmussen encephalitis, suggesting that these two conditions may share common etiologic factors.

Suppression of genioglossus muscle tone and activity during reflex hypercapnic stimulation by GABA(A) mechanisms at the hypoglossal motor nucleus in vivo

The genioglossus muscle is involved in the maintenance of an open airway for effective breathing. Inhibitory neurotransmitters may be responsible for the major suppression of hypoglossal motor output to genioglossus muscle that occurs in certain behaviours such as rapid-eye-movement sleep. There is evidence for GABA(A) receptor-mediated inhibition of hypoglossal motoneurons in vitro. However, comparable studies have not been performed in vivo and the interactions of such mechanisms with integrative reflex respiratory control have also not been determined. Urethane-anaesthetised, tracheotomized and vagotomized rats were studied whilst diaphragm and genioglossus muscle activities, blood pressure and the electroencephalogram were recorded. Microdialysis probes were implanted into the hypoglossal motor nucleus, with sites verified by histology. Genioglossus responses to microdialysis perfusion of muscimol (GABA(A) agonist: 0, 0.1, 1 and 10 microM in artificial cerebrospinal fluid) were recorded at inspired CO(2)s of 0, 5 and 7.5% in six rats. Responses to bicuculline (GABA(A) antagonist, 0, 1, 10, 100 and 1000 microM) were also studied in six rats with and without CO(2) stimulation. Genioglossus activity decreased with muscimol (P<0.0001), with major suppression at 1 and 10 microM during air breathing (decreases=70.2% and 92.8%, P<0.005). Genioglossus activity increased with CO(2) (P=0.003), but genioglossus activation with 5 and 7.5% CO(2) were almost abolished with 10-microM muscimol. Responses were specific to genioglossus muscle as there were no changes in diaphragm, respiratory rate or blood pressure with muscimol (P>0.144). Antagonism of GABA(A) receptors increased genioglossus activity (P<0.001). These results show that GABA(A) receptor stimulation at the hypoglossal motor nucleus suppresses both genioglossus muscle tone and activity in the presence of reflex stimulation produced by hypercapnia. Recruitment of such mechanisms may contribute to the major suppression of genioglossus activity observed with and without CO(2) stimulation in behaviours such as rapid-eye-movement sleep.