KOWSAR MEDICAL JOURNAL
Year:2007 | Volume:12 | Issue:3 |Papers Count:14

Objective: This study was conducted to characterize the inhibitory effects of Ryanodineon pacemaker activity of the sinoatrial node (SAN) and the atrioventricular node (AVN) in rat. The method of this study was experimental and two separate metal microelectrodes were used for extracellular recording of electrical activity. The effect of ryanodine on electrical activity was studied by measuring cycle length (CL). Paired and unpaired T-student test were used for analyzing data. Inhibition of RyR by 2uM ryanodine increased CL from 283.75±27 to 412.50±82 ms on SAN and from 516.25±195 to 1570±400 mson AVN. This increase in CL is 39.50±12.8% in SAN preparations while 186±57.50% in AVN preparations (p< 0.05). Pacemaker activity was not stopped in none of the preparations.It is possible to conclude that: (i) the ryanodine receptor current exists in SAN & VAN. The peacemaking activity did not stop functioning in cardiac nodes after ryanodine was used, which means that the role of RyR for pacemaker activity is not obligatory.(ii) The effect of ryanodine on AVN was significantly greater than SAN; that is, the role of RyR is not similar in those two nodes.

Introduction: Ischemic preconditioning (IPC) is an endogenous phenomenon that can induce ischemic tolerance (IT) in a variety of organs such as brain. Noxious stimuli applied at close to but below the threshold of cell injury induce adaptive responses that protect the brain against additional stress from the same (tolerance) or other (cross-tolerance) stimuli. In this study, we examined the effect of intermittent and prolonged doses of normobaric hyperoxia (NBHO) on neurologic deficit scores, serum TNF-a level, and gene expression of TNF-a converting enzyme (TACE).Material and Method: The rats were exposed to NBHO in prolonged (24h) and intermittent (every 4 hours for 6 days) groups. Each group subdivided into three subgroups. After 24 hours, the first subgroup underwent MCAO for 60 minutes followed by 24h of reperfusion. Then, IT induced by intermittent and prolonged NBHO were measured by neurologic deficit scores. The second and third subgroups, called sham-operated and intact subgroups respectively, were considered for the assessment of the effect of NBHO on serum TNF-a level and gene expression of TNF-a converting enzyme.Result: Our findings indicated that intermittent and prolonged NBHO were involved in the induction of IT. Pretreatment with prolonged and intermittent NBHO reduced neurologic deficit scores significantly. Prolonged and intermittent NBHO increased serum TNF-a level and gene expression of TNF-a converting enzyme with the effect of prolonged NBHO being significantly stronger. Also, intermittent NBHO with ischemia significantly increased serum TNF-a level and gene expression of TNF-a converting enzyme rather than intermittent NBHO alone. Conclusion: Although further studies are needed to clarify the mechanisms of ischemic tolerance, intermittent and prolonged NBHO seem to partly exert their effects via increasing serum TNF-a levels and up regulation of TNF-a converting enzyme.

Introduction: Previous studies have indicated that glucocorticoids receptors (GRs) are involved in leamirrg and memory processes and probably basolateral amygdala is one of the brain noc1ei that mediates this role. Therefore, this study was aimed to determine the role of basolateral amygdala (BLA) nucleus in corticosterone effects on memory retrieval in rats.Material and Methods: In this experimental study, 110 male Wistar rats (250-300 gr) were used. In experiment l, bilateral cannulae were surgically aimed at BLA and the rats were trained using passive avoidance learning (PAL) task one week later. Retention test was done two days later, during which re-entering into dark chamber (Step-through latency, STL) and time spent in light chamber (TLC) was recorded in a 10 minute test and the results were compared with the control group. 30 minutes before the retrieval test, bilateral intra-BLA injections of corticosterone (0.1, 0.5, 1 and 3 /lg for each side) were made. In experiment 2, one week after BLA of the rats were chemically destroyed by NMDA, they were trained using PAL as mentioned above. Thirty min before the retrieval test which was done 2 days after training; corticosterone (1, 3 mg/kg) was injected subcutaneously and results were compared with the sham group. In the end, the possible effects of BLA destruction on their locomotor activity were studied.Results: Data indicated that injection of corticosterone into BLA impaired memory retrieval in a dose- dependent manner (P<0.01). Also, effects of systemic corticosterone administration were balanced in the presence of destroyed BLA (P<0.01). BLA destruction did not cause locomotor disorders.Conclusion: Findings show that activation of GRs in BLA plays an important role in retrieval memory and BLA has a critical role in mediating the effects of systemic glucocorticoids on retrieval memory.

Introduction: In this study, the relationship between glucose-6-phosphate dehydrogenase inhibition in macrophages treated with dehydroepiandrosterone and the amount of nitric oxide (NO) production and leishmania major amastigotes replication in infected macrophages were investigated.Materials and Methods: Peritoneal macrophages of BALB/c mice were isolated and treated with different concentrations (50, 100, 150,200 mm) of dehydroepiandrosterone (DHEA). After incubation for 24 hours, the viability of treated macrophages was measured by MTT assay at 570 nm. G6PD activity was measured in the cell extracts after 24 hours of incubation. Also, macrophages were infected with leishmanial promastigotes and after 18 hours, NO production was determined using Griess-reagent. 100 mm concentration of DHEA was used to study the inhibition of macrophage leishmanicidal activity and the increase in the number of leishmanial amastigotes in these cells from day 1 to 7.Results: Results showed that different concentrations of DHEA significantly increased cell cytotoxicity and decreased G6PD activity and NO production in macrophages. Also, the number of amastigotes in macrophages increased significantly (P£0.001).Conclusion: In this study dehydroepiandrosterone decreased G6PD activity which correlated with the decrease in production of NO and an increase in the cytotoxicity of BALB/c mice peritoneal macrophages. Accordingly, any decrease in G6PD activity lowers NO production and increases cell death. NO has a critical role in leishmanicidal activity of macrophages, so inhibition of G6PD activity decreased leishmanicidat activity of mouse peritoneal macrophages.

Introduction: The aim of this study was to examine whether the stimulatory effect of lowintensity pulsed ultrasound results in increased bone trabeculae and/or cell proliferation. Materials and Methods: Twenty adult male Dutch rabbits were divided into one control (sham) and two ultrasound stimulation groups. Under anesthesia, a standardized mid-tibial osteotomy was created in the right tibial bone. Bilateral external fixator was applied to both aspects of the leg. Three days after the surgery, the rabbits in the ultrasound groups received ultrasound pulses with the intensity of 50 and 100 mw/cm2 for 15 min/day. Ultrasound was also utilized in the control group but the intensity was zero mw/cm2.The rabbits were killed at week 7 post surgeries by inhalation of chlorophorm. For histological evaluation, the callus fracture tissues were processed. The samples were fixed in 10% formaldehyde, decalcified in 5% nitric acid, processed in the tissue processor and embedded in paraffin wax. The paraffin blocks were sectioned longitudinally at 5 microns and were then stained with hematoxylin - eosin (H&E) and massons trichrome.Result: The slides were studied for histomorphometric evaluation of trabecula and connective vascular tissue in the callus area. Slides were used for cell counting of osteoblast in the callus region in all groups. In addition, some slides were used for immunohistochemical study using ki67 marker to study the cell proliferation of osteoblasts in the callus region in all groups. Data was then compared in all groups. Histomorphometric evaluation demonstrated that the mean of trabeculae in the fracture area was 64.4±4.06 in the control group while it was 56/57±3/81 in 50 mw/cm2 ultrasound group and 84.04±5.74 in 100 mw/cm ultrasound group. There were no significant differences between ultrasound and control groups (p<0.05).The mean osteoblast number in the fracture area was 23.26±1.08 in the control group while it was 17.58±0.95 in the first ultrasound group (50 mw/cm2) and 26.80±1.65 in the second ultrasound group (100 mw/cm2).There were no significant differences between ultrasound and control groups (p<0.05). Conclusion: These results showed that fractured callus tissue is not sensitive to this level of ultrasound application and it had no effect on fracture repair and callus formation in rabbits tibiae.

Introduction: There are a lot of surgical methods for the treatment of morbidly obese patients. Biliointestinal Bypass (BIB), a Bariatric surgery, produces significant long term weight reduction by malabsorption in the intestine. This operation is a modification of Jejunoileal bypass (JIB) with anastomosis of the proximal end of jejunum to the fundus of the gall bladder.In this study, we evaluated the efficacy and complications of JIB in the treatment of morbid obesity.Materials and Methods: The indication for the surgery was BMI > 40 or BMI =35-40 with comorbid illness. In this prospective study that was conducted between Sep 2004 and March 2006, 23 patients (16 female and 7 male), with median weight of 125±18 and (mean???) body mass index of 44±5, underwent BIB surgery in khatam and Baqiyatallah(a.s) hospitals. At least 83% of the patients complained of one of the co-morbid illnesses due to excess weight such as musculoskeletal problems, diabetes, cardio-pulmonary diseases, etc. After surgery, the patients were evaluated for weight reduction and other surgical and metabolic complications for averagely 16months (11-24 mo).Results: During follow up, there were no significant adverse metabolic complications. None of the patients had DVT or PE and the mortality rate was zero. The average weight reduction after 6, 12, 18 and 24 months were 22.1, 34.5, 39.6 and 42.5 Kg, respectively. The average BMI after 6, 12, 18 and 24 months were 37.5, 33, 32 and 33, respectively. Diarrhea was the most frequent complication which was observed in 21% of the patients Two (8.6%) incisional hernias were observed because of postoperative wound infection. This study showed that the amount of weight loss was significantly better in men.Conclusion: BIB is a simple and reversible method for the morbidly obese patients.Anastomosis of the proximal end of jejunum to the gall bladder eliminates the blind loop in JIB and maintains entrohepatic circulation of bile and prevents bacterial overgrowth, renal calculi formation and hepatic failure and in comparison with the original technique, reduces the risk of metabolic side effects.

Introduction: Coronary artery disease (CAD) is the most common cause of death in most countries. Its prevalence is associated with factors such as age, sex, loss of physical activity and positive family history. Several other risk factors including smoking, hypertension, diabetes and hyperlipidemia may contribute to its development. This study aimed to determine the frequency of some major risk factors of CAD in military patients in comparison with non-military patients.Materials & Methods: This cross-sectional study was performed on 5442 patients who presented with complaints suspicious of having originated from CAD and candidated for coronary angiography in Jamaran and Baqiyatallah hospitals. Data was collected and analyzed with SPSS 11.5 for Windows package using Chi-square, t-test and ANOVA statistical methods. P-values <0.05 was statistically significant.Results: Mean age was 48.6±9.4, 55.05±10 and 59.1±9.9 years of age in Revolutionary Guards (Pasdar) patients, Army (Artesh) patients and in non-military patients, respectively (p=0.001).The frequency of risk factors in the Pasdar group was as follows: smoking 37.5%, hyperlipidemia 31.3%, hypertension 21.1% and diabetes 19.8% while it was the following in the army group: smoking 38.9%, hyperlipidemia 38.4%, hypertension 31.1% and diabetes 15.8%. In non-military patients smoking was observed in 25.4% of cases, hyperlipidemia in 34.6%, hypertension in 47.1% and diabetes in 24.5% of cases.Discussion: Age distribution and pattern of risk factors were significantly different in military and non-military patients. Smoking was the most frequent risk factor in military cases but it was hypertension in non-military cases.

Introduction: Bronchiolar abnormalities play an important role in the pathogenesis of chronic lung complications in mustard gas exposed patients. Also, the outcome of inhaler maintenance therapy in these patients is not clear. We examined the role of two regimens of combination inhaler therapy on the reversibility of the symptoms in these patients.Materials and Methods: In a phase Ill, prospective randomized clinical trial, group 1 (n=36) received Seretide, a combination of Fluticasone propionate (125 mg) and Salmetrol (25 mg) 2 puffs daily and group 2 (n=30) received Beclomethasone (250 mg) and Salbutamol inhaler (200 mg) 4 puffs daily for 12 weeks. Respiratory symptoms (including dyspnea, night awakening due to dyspnea and cough) were assessed using three multiple choice questions before and after medical intervention. Furthermore, dyspnea status was assessed by Visualized Analogue Scale (VAS) at weeks 0, 4, 8, 12 and 14. PFT was performed for all patients in each visit.Results: Both medication regimes increased post-treatment FEV1, FVC, FEVIIFVC% and PEF by the end of the 12th week. It seems that these improvements are more constant in group 1 than group 2. Reversibility, which is defined as 10% increase in FEVI in the 2nd month, was seen in 27% of the patients in group 1 and 7% in group 2. VAS scores decreased in two groups during treatment period (p= 0.003) but remained sustained only in group 1 after follow up period. Discussion: Inhaled corticosteroids and long-acting b2-agonistsare effective in the treatment of patients with chronic bronchiolitis following exposure to sulfur mustard. Airway obstruction is to some extent reversible in chemical injured victims. Seretide, a newer generation of inhaled corticosteroid (ICS) with half dose, has the same effect on the airways reversibility in comparison with previous high dose ones such as Beclomethasone.

Introduction: The ability to respond quickly and effectively to a cardiac arrest situation rests on nurses being competent in the emergency life-saving procedure of cardiopulmonary resuscitation (CPR). The aim of this study was to investigate the extent to which nurses' acquire and retain CPR cognitive knowledge and psychomotor skills following CPR training.Materials and Methods: A quasi-experimental time series design was used. CPR knowledge was assessed by a multiple-choice assessment and psychomotor skills were assessed by observing CPR performance on a Resusci manikin in 3 steps (pre-test, , post-test, and re-test).Results: The findings showed an acquisition in nurses' CPR knowledge and psychomotor performance following a 4 h CPR training programmed [mean (STD) of knowledge and psychomotor skills: 17.96(1.74), 24.41(2.17)]. A deterioration in both CPR knowledge and skills was found 10 weeks following CPR training [mean (STD) of knowledge and psychomotor skills: 16.12(2.51), 21.46(4.12)]. However, nurses' knowledge and skills were improved over their pertaining scores [mean (STD) of knowledge and psychomotor skills: 10.95(2.97), 4.86(4.74)], which clearly indicated a positive retention in CPR cognitive knowledge and psychomotor skills (P value=0.000).Conclusions: The study findings present strong evidence to support the critical role of CPR training in ensuring that nurses progress to competent and confident responders in BLS especially in the event of a cardiac related emergency.

Introduction: It is very important to consider that increased intra-abdominal pressure above the terminal capillary blood pressure causes progressive tissue hypoperfusion, ischemia of the intestines and kidneys as well as other peritoneal and retroperitoneal structures.Materials and Methods: Eleven patients out of 3415 admitted patients in Alzahra and Issabne Maryam (SA) Hospitals were diagnosed to have abdominal compartment syndrome (ACS) between 1999 and 2006. Cases with intra-abdominal pressure of 26 to 35 CmH20 and clinical signs of ACS, anuria, hypoxia and tachycardia were decompressed. Patients with intraabdominal pressure of 36cm H2O or higher were decompressed urgently.Results: Eleven patients (7 males, 4 females) were studied with the youngest being 18 and the oldest being 86. Mortality rate was 64%. One of the important causes of increased mortality was prolonged ACS duration and abdominal decompression delay. The most probable causes of ACS were severe abdominal trauma, sepsis and aggressive resuscitation.Conclusion: High index of suspicion for ACS has an important role in its diagnosis and further life saving.