Non-dipping pattern of nocturnal blood pressure in obstructive sleep apnea syndrome: possible role of oxidative stress and endothelin-1 precursor

There is growing evidence suggesting that obstructive sleep apnea OSA is linked to the occurrence of cardiovascular disorders. Lack of normal nocturnal dipping of blood pressure has also been considered a risk factor for the occurrence of cardiovascular disorders. Non-dipping has been described in patients with OSA and is attributed to autonomic dysfunction. However, the search for a causal link between OSA and cardiovascular disease is still underway. To evaluate the occurrence of non-dipping pattern of nocturnal blood pressure, and the possible role of oxidative stress and ET-1 precursor in patients with OSA. Thirty eight patients with OSA and fourteen normal control subjects were enrolled in this study and were subjected to history taking, clinical examination, early morning blood samplings for the measurement of serum malondialdehyde [MDA] and endothelin 1 precursor [ET-1 precursor]. All patients with OSA were subjected to full polysomnographic study and monitoring of nocturnal blood pressure changes. Nocturnal blood pressure measurement of all patients revealed that thirty six patients [94.7%] were non-dippers, 15 patients [39.5%] suffered from ischemic heart disease. Serum endothelin-1 precursor and serum malondialdehyde levels were significantly higher in patients with OSA than in the control group. The systolic blood pressure measured before sleep was also significantly higher in patients than in the control group. The Epworth sleepiness scale and the clinical apnea score were significantly higher in patients than in the control group. The high incidence of non-dipping pattern of nocturnal blood pressure in both normotensive and hypertensive patients with OSA may be considered a warning sign for the occurrence of cardiovascular complications in these patients. Both increased oxidative stress and ET-1 precursor may be among the causative factors responsible for the high prevalence of the non-dipping pattern through increasing sympathetic nervous system activity

Effect of intrahippocampal insulin injection on memory performance in normal and diabetic rats

This work was designed to demonstrate the effect of diabetes on memory performance in rats and to evaluate the effect of intrahippocampal administration of insulin on memory retention consolidation] in normal non diabetic and diabetic adult male rats. The study consisted of 48 adult Wistar male rats with weights ranging from [185-200] gm. Rats were divided into 2 groups: group A consisted of 24 normal non diabetic rats and group B consisted of 24 diabetic rats. The study was divided into 2 experiments: Experiment 1 aimed to compare between the performance of normal non diabetic and diabetic rats during water maze training. It was performed on 16 rats: 8 normal rats from group A and 8 diabetic rats from group B. All rats were trained in the water maze for 5 consecutive days to reach a hidden platform in the pool. Each day consisted of 8 training sections. The time required and distance traveled to reach the hidden platform was measured and the time spent in the target quadrant of the pool was calculated [expressed as a percent of the total time spent in the pool] each day. Experiment 2 aimed to test effect of post training intrahippocampal insulin injection on memory retention [consolidation] in normal and diabetic rats. This experiment was performed on 32 rats: 16 normal rats from group A, and 16 diabetic rats from group B. The normal rats were divided into an intrahippocampal saline injected group [n=8] and an intrahippocampal insulin injected group [n=8]. Similarly the diabetic rats were divided into intrahippocampal saline injected group [n=8] and an intrahippocampal insulin injected group [n=8]. Rats were trained for one day on the water maze; the training session consisted of 8 trials 60 seconds each. Retention testing, used to test consolidation, consisted or 60 seconds of a free swimming period without the platform. The percent of the time spent and the percent of the distance swum in the target quadrant were calculated and the number of escape trials from the edge of the pool was measured. Experiment 1 showed that the performance of diabetic rats was significantly impaired when compared with the control group. Diabetic rats took a significantly longer time, and swam a significantly longer distance to reach the hidden platform when compared with control rats in each of the 5 days of training. Furthermore, the percent of time spent in the target quadrant of the pool was significantly lower when compared with the control rats. Experiment 2 showed that Intrahippocampal insulin injection enhanced memory consolidation in insulin injected normal rats when compared with saline injected normal rats as evidenced by a significantly higher percent of time spent and distance swum in the target quadrant of the pool in the insulin injected normal rats during retention testing. Furthermore, the number of escape trials from the edge of the pool was significantly lower in insulin injected normal rats when compared with saline injected normal rats. Similarly, intrahippocampal insulin injection in diabetic rats enhanced memory consolidation. However, when comparing diabetic insulin injected rats with normal saline injected rats their performance was impaired indicating a partial improving effect of intrahippocampal insulin on memory consolidation in diabetic rats. The present work demonstrated that intrahippocampal administration of insulin has an enhancing effect on memory consolidation in normal rats and resulted in a partial improvement of memory consolidation in diabetic rats. Implications of this research point to a potential therapeutic role of central insulin administration through the intranasal route for enhancement of memory consolidation

Effect of centrally and peripherally administered obestatin on food and water intake in rats

This work was designed to study the effects of acute obestatin administration on food and water intake, as well as on body weight in rats. In addition, the effect of blocking the efferent cholinergic vagal fibers on food intake was also tested in search for a possible mechanism of action. The study was carried out on 48 adult male rats with weight ranging from [185-200] grams and was divided into 3 sections. Section A intracerebroventricular [ICV] injection: consisted of 24 rats that were divided into 4 groups [6 / group]. Rats in group 1 served as control and were injected with ICV saline. Rats in groups 2, 3, 4 were injected ICV obestatin in doses 15, 25, 50 nM/kg, respectively. Section B intraperitoneal injection: Which included 24 rats divided into 4 groups [6 / group]. Rats in group 1 were injected with IP saline [control group]. Obestatin was injected by IP route in the other groups: 2, 3, 4 in doses of 50, 100, 1000 nM/ kg, respectively. Cumulative water and food intake were monitored at 1, 3, 6 and 24 hours after both ICV and IP obestatin injection and were expressed per rat. Plasma osmolality was measured at 3 and 6 hours after ICV and IP obestatin injection. The differences in body weight of rats were recorded at the end of 24 hours. Section C: rats in the 2 groups injected with the highest doses of obestatin [50 nM/kg ICV and 1000 nM/kg IP] were selected the following day and pretreated with atropine sulphate IP in a dose of 500 ug/kg.15 minutes before they were reinjected with obestatin in the same doses used in the previous day. Food and water intake were assessed after 3 hours of injection. ICV and IF injection of obestatin revealed a significantly lower water intake versus the control that appeared at 3 hours after ICV [15 nM/kg obestatin] and also at 3 hours after IP [100 nM/kg obestatin]. With higher doses of obestatin injection [ICV 25 and 50 nM/kg and IP 1000 nM/kg] the inhibition of water intake showed a significant dose dependant effect at 1 and 3 hours. Plasma osmolality showed no significant difference when compared between the studied groups after both ICV and IP obestatin injections at 3 and 6 hours. The inhibition of food intake occurred only at 3 hours with the highest doses of obestatin injected [ICV 50 nM/kg and P 1000 nM/kg] compared with the control group. No significant differences were detected in water and food intakes and also in body weight differences after 24 hours compared with the control after obestatin injection by either ICV or P routes. As regards testing the possible involvement of vagal efferent cholinergic mechanism in obestatin's action, the groups injected with the highest doses of obestatin [50 nM/kg ICV and 1000 nM/kg IP] 15 minutes after atropine premedication as well as the non pretreated groups showed a significant decrease of water and food intake at 3 hours compared with the control group. Furthermore, there were no statistically significant differences between atropine pretreated and non pretreated groups injected by the highest obestatin doses as regards food and water intake. Obestatin primarily has an effect to inhibit thirst after acute administration probably by an effect on one of the circumventricular organs. It has a weaker effect on food intake. may be because it has to diffuse to food regulating centers in the brain or because the food intake is regulated by several peptides that may antagonize each other. The vagus efferent cholinergic mechanism has no role in the inhibitory effect of obestatin on food intake. Obestatin should gain more attention as a peptide regulating water balance rather than food intake and its effect on angiotensin II and vasopressin should be investigated

Value of wave III as an early warning sign in intraoperative brainstem auditory evoked potential monitoring

The use of Intraoperative brainstem auditory evoked potential monitoring [auditory brainstem response, ABR] has been shown to reduce the risk of hearing impairment during cerebello-pontine angle [CPA] surgeries that place the cochlear nerve at risk. Despite its wide use however, studies defining the changes in intraoperative ABR that correlates to hearing impairment are inconsistent. Loss of ABR wave V although a specific sign of postoeprative hearing impairment is not helpful for hearing preservation because its occurrence is a late indication of compromise of hearing. For increasing the efficacy of hearing preservation its would be more practical to rely on earlier warning criteria. To evaluate the value of wave III as an early warning sign for ABR changes and in predicting postoperative hearing outcome during surgery for microvascular decompression [MVD] procedures and vestibular neurectomies. The study was conducted on a total of 30 patients who underwent surgery for MVD procedures and vestibular neurectomies. All patients underwent pure-tone audiometery and speech discrimination immediately before and 10-12 days following surgery. Hearing was classified into four classes based on pure tone average [PTA] and speech discrimination scores. Hearing preservation was attempted in all surgeries using ABR. During the operation ABR was recorded continuously and the latencies and amplitudes of waves I, III and V were compared with those of the baseline recordings. The amplitude of the wave was measured between its peak and the following trough, the ratio of that amplitude value to that of the baseline recording was expressed as a percentage. Out of 30 patients, 21 [70%] had preserved postoperative hearing and 9 [30%] had reduced hearing postoperatively. ABR changes [latency and/or amplitude] in wave III and V occurred in 25 [83.3%] of cases. Of those 25 cases, wave III changes preceded wave V changes in 14 cases [56%]. Delay of latencies of both waves III and V could significantly predict postoperative outcome [cutoff values: 0.6 and 0.62msec respectively]. Comparison between areas under the ROC curve [receiver operated characteristic curve] of latency delay of wave III and wave V in relation to postoperative hearing outcome revealed that although delay of latency of wave V had higher value of area under the curve [0.852] than delay of wave III latency [0.733], there was no statistical significant difference between both variables [p=0.240]. In addition, percent decrease of amplitude of both waves III and V could significantly predict hearing outcome [cutoff values 40% and 42.8% respectively]. Comparison between areas under the ROC curve of percent decrease of amplitude of waves III and wave V in relation to postoperative hearing outcome revealed that the area under the ROC curve of percent decrease of amplitude of wave III [0.929] was significantly higher than that of wave V [0.725] [p=0.028]. Further more, the study revealed that 0.4 msec delay of wave III amplitude was an early alert to more significant changes. Changes in wave III latency and amplitude can predict postoperative hearing outcome as efficient as wave V changes. Furthermore, a more gradual line of ABR changes should be adopted as warning criteria starting with 0.4 msec delay of wave III. A second level of warning at which the surgeon must be alerted includes any of the following single or in combination: a 0.6 msec delay or more of latency of either waves III or V, and more than 40% decrease amplitude of waves III and or V

Effect of Schistosoma mansoni infection on physiological gastrointestinal transit and contractility

Schistosoma mansoni [S. mansoni] is a major health problem; a large proportion of infected individuals suffer from motility-related gastrointestinal disturbances. However, the exact relationship between the gastrointestinal motility changes, the enteric nervous system neuronal excitability, and the complexity of the resulting symptoms, in both the acute and chronic phases of inflammation are still not clear. The work was designed to investigate the effect of two different intensities of S. mansoni infection on gastrointestinal transit and contractility of the colonic muscles, in both acute and chronic phases of inflammation of experimentally infected mice; and to asses the relation between gastrointestinal transit, contractility, and serum antigen and antibody levels. The study was conducted on 60 mice divided into 2 groups a control group consisting of 12 mice, and S. mansoni infected group consisting of 48 mice. The infected group was further subdivided into two subgroups, each infected by a different intensity of cercaria [50 and 200 cercaria/mouse]. Gatrointesintal transit and contractility were recorded from the colon of each group and were analyzed at the acute [8[th] week] and chronic phase [12[th] week] of inflammation. In addition, the immunological changes of the host were assessed in both infected subgroups of mice, at the same studied durations. At 8weeks postinfection, in both infected subgroups, gastrointestinal transit was significantly decreased, in concurrent with significant increase in the colonic muscle contractility, compared to the control group. At that time, the serum antigen was absent, while the serum antibody was detectable at low titre. However, at twelve weeks postinfection, there was a further statistically significant decrease in gastrointestinal transit, and increase in the colonic muscle contractility. These alterations were coinciding with absence of serum antigen and increase in the antibody titre. All changes were more pronounced in the second infected subgroup [200 cercaria/mouse] than the first infected one [50 cercaria/mouse], Indicating that the increased host immunity at the 12[th] week postinfection did not improve the motility disorder of the colon. We conclude that intestinal schistosomiasis is associated with disturbances in gastrointestinal transit and contractility, which are related to the time course and the intensity of the infection, and may be involved in the pathogenesis of the motility disorder associated with the disease. The hypercontractility in the acute phase can be explained by functional changes in the excitability of enteric nervous system neurons due to the release of mediators, and in the chronic phase due to granuloma formation leading to structural changes in the enteric nervous system. Elucidation of the mechanism whereby inflammation alters enteric nervous control of gastrointestinal function may lead to novel treatments of motility disorders of the disease

possible role of visceral adiposity in development of pro-atherogenic lipid profile in normal overweight young Egyptian female adults [a possible involvement of adiponectin and leptin]

The metabolic abnormalities that often co-exist with overweight and obesity appear to be mediated largely by visceral fat accumulation. Visceral fat is very different from the subcutaneous fat, and may be responsible for pro-atherogenic lipid profile in apparently healthy people. to examine the influence of visceral fat and "not obesity" on the lipid profile. In addition, to test the relation between adipocytokines [leptin and adiponectin] and lipid profile in overweight young healthy Egyptian adult females. Forty healthy young overweight females participated in this prospective cohort study, their age ranged from 19-23 Y, and their body mass index [BMI] ranged from 25-30 Kg/rn2. All the participants were completely healthy with no history of thyroid dysfunction; diabetes; or cardiovascular, renal, or liver dysfunction. No participant had taken medication for at least 3 months before the study, and none were dieting or smoking. The anthropometric measurements were made be the same observer in the physiology laboratory, Alexandria University, they induced: height, weight, body mass index [BMI], waist, hip circumference and waist hip ratio [WHR]. Fasting venous blood was collected to measure adipocytokines [leptin and adiponectin] and lipid profile [total cholesterol [TC], total triglycerides [TG], high-density hpoprotein cholesterol HDL-C, low-density lip oprotein cholesterol [LDL-C] and the LDL-C/HDL-C ratio was calculated as the atherogenic index. Then the examined subjects were divided into two groups based on their Waist/hip ratio [WHR]. Group 1 [n 25 with WHR>0.8], and group2 [n=15 with WHR