Extracellular vesicles from the infarcted and failing heart drive tumor growth

Aims

Heart disease might be an independent risk factor for cancer (reverse cardio-oncology). The co-occurrence of these diseases worsens patients' prognoses and limits therapeutic options. However, the cellular and molecular mechanisms that link heart disease to cancer remain elusive. Therefore, we hypothesized that cardiac extracellular vesicles (cEVs) secreted by diseased hearts carry and disseminate factors that promote tumor growth.

Methods and results

We subjected female mice to myocardial infarction (MI) or sham-MI and 28 days of follow-up. Left ventricular remodeling and dysfunction were assessed by echocardiography. To determine the role of cEVs in tumor growth, we focused on cardiac mesenchymal stromal cells (cMSCs), which play a central role in cardiac repair, remodeling, and fibrosis. We isolated cMSCs from mice hearts 10 or 28 days after MI or sham MI and purified cMSC-EVs from the conditioned medium using size exclusion chromatography. cEVs were characterized by nanoparticle tracking analysis (NTA), the classical EV markers: CD81 and Tumor susceptibility gene 101, and electron microscopy. cMSCs after MI secreted more small EVs than cMSCs from sham-MI (Fig. 1A, p<0.0001). Proteomic and biological process analysis revealed a distinctive profile of cEVs after MI with more EV-encapsulated proteins related to inflammation, angiogenesis, and cell cycle (Fig. 1B). Purified cMSC-EVs were labeled with PKH26 dye and found to target both breast and lung cancer cells in vitro. Colorimetric proliferation assay showed that MI-cEVs facilitated cancer cells proliferation compared with sham-MI cEVs (n=7 in each group, p<0.0001). Furthermore, by scratch assay, MI-cEVs facilitated cancer cell migration two times faster than sham-MI cEVs (Fig. 1C, p=0.0002). Finally, we established 2 models of heart disease with cancer. Lung or breast cancer cells (750x103 or 250x103) were inoculated into the hind limb or mammary pad 10 days before or after MI. Serial ultrasound examinations monitored tumor growth. While MI significantly stimulated lung cancer growth, EV inhibition by GW4869 markedly attenuated the tumorigenic effect of MI and left ventricular (LV) dysfunction (Fig. 1D, p for GW4869 <0.0001). Moreover, we found an inverse correlation between LV ejection fraction (LVEF) and the volume of breast cancer tumors. cEV inhibition by GW4869 attenuated this inverse correlation (for vehicle group: n=14, r=−0.54 and p=0.04. for GW4869 group: n=13, r=−0.43, and p=0.14).

Conclusions

Our results suggest, for the first time, that cMSCs from the infarcted and failing heart secret EVs that target tumor cells and accelerate tumor growth. We propose cEVs as potential mediators and therapeutic targets in patients with concomitant heart disease and cancer.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Seymour Fefer Grant

Automated processing of thermal imaging to detect COVID-19 and microvascular dysfunction

Background

Coronavirus disease 2019 (COVID-19) is associated with microvascular dysfunction. Non-invasive thermal imaging can hypothetically detect changes in perfusion, inflammation and vascular injury. We sought to develop a new point-of-care, non-contact thermal imaging tool to detect COVID-19 by microvascular dysfunction, based on image processing algorithms and machine learning analysis.

Materials and methods

We captured thermal images of the back of 101 individuals, with (n=62) and without (n=39) COVID-19, using a portable thermal camera that connects directly to smartphones. We developed new image processing algorithms that automatically extract multiple texture and shape features of the thermal images (Figure 1A). We then evaluated the ability of our thermal features to detect COVID-19 and systemic changes of heat distribution associated with microvascular disease. We also assessed correlations between thermal imaging to conventional biomarkers and chest X-ray (CXR).

Results

Our novel image processing algorithms achieved up to 92% sensitivity in detecting COVID-19 with an area under the curve of 0.85 (95% CI: 0.78, 0.93; p<0.01). Systemic alterations in blood flow associated with vascular disease were observed across the entire back. Thermal imaging scores were inversely correlated with clinical variables associated with COVID-19 disease progression, including blood oxygen saturation, C- reactive protein, and D-dimer. The thermal imaging findings were not correlated with the results of CXR.

Conclusions

We show, for the first time, that a hand-held thermal imaging device can be used to detect COVID-19. Non-invasive thermal imaging could be used to screen for COVID-19 in out-of-hospital settings, especially in low-income regions with limited imaging resources. Moreover, thermal imaging might detect micro-angiopathies and endothelial dysfunction in patients with COVID-19 and could possibly improve risk stratification of infected individuals (Figure 1B).

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): 1. The Israel Innovation Authority2. The Nicholas and Elizabeth Slezak Super Center for Cardiac Research and Biomedical Engineering at Tel Aviv University Figure 1. A. Representative steps of our thermal image processing algorithms. B. A schematic illustration of the research design and potential impact.

Diabetes prevention program in a Mediterranean environment: individual or group therapy? An effectiveness evaluation

INTRODUCTION

Diabetes as a multifactorial disorder requires prevention measures based upon the modification of several risk factors simultaneously; otherwise, there is insufficient potential for prevention. Following the success of the American Diabetes Prevention Program (DPP), we implemented an intervention program in a large Israeli healthcare organization with an emphasize on Mediterranean Diet (MedDiet) and physical activity. The objective was to evaluate the effectiveness of two types of intervention, individual and group therapies, in reducing risk factors and in preventing or delaying the development of type 2 diabetes.

METHODS

Out of 180 primary care physicians, 85 who agreed to participate, were randomly assigned, between the years 2005 and 2006, into two groups: those who would refer pre-diabetes adult patients for individual therapy and those who would refer for group therapy. The two groups of patients consisted of 111 and 112 in each group. The intervention lasted for 6 months and discussed: the benefits of MedDiet, planning nutritional behavior and mindful eating, and the importance of physical activity. All patients were invited to participate in walking groups. Follow up lasted for 24 months and logistic, mixed models, and Cox regressions were employed.

RESULTS

No statistically significant differences were detected between the two intervention groups in age; gender and clinical measurements at recruitment. Thirty nine percent of both groups developed diabetes (entered the DR by 2012), including 38.7% from the individual therapy and 39.3% from the group therapy (P=0.933). The mean time from 2005 until entry to the Diabetes Registry (DR) was 2.9 and 2.5 years for the individual and group therapy respectively (P=0.542).

CONCLUSION

Both interventions were equally effective in achieving the desired outcomes and time until entry to the DR. For large health organizations with a high number of pre-diabetes patients and scarce resources, group therapy, where 12 people are reached out by one team member are preferable and more costly effective, than a one on one therapy.

Capsule endoscopy in acute upper gastrointestinal hemorrhage: a prospective cohort study

BACKGROUND AND STUDY AIMS

Capsule endoscopy may play a role in the evaluation of patients presenting with acute upper gastrointestinal hemorrhage in the emergency department.

PATIENTS AND METHODS

We evaluated adults with acute upper gastrointestinal hemorrhage presenting to the emergency departments of two academic centers. Patients ingested a wireless video capsule, which was followed immediately by a nasogastric tube aspiration and later by esophagogastroduodenoscopy (EGD). We compared capsule endoscopy with nasogastric tube aspiration for determination of the presence of blood, and with EGD for discrimination of the source of bleeding, identification of peptic/inflammatory lesions, safety, and patient satisfaction.

RESULTS

The study enrolled 49 patients (32 men, 17 women; mean age 58.3 ± 19 years), but three patients did not complete the capsule endoscopy and five were intolerant of the nasogastric tube. Blood was detected in the upper gastrointestinal tract significantly more often by capsule endoscopy (15 /18 [83.3 %]) than by nasogastric tube aspiration (6 /18 [33.3 %]; P = 0.035). There was no significant difference in the identification of peptic/inflammatory lesions between capsule endoscopy (27 /40 [67.5 %]) and EGD (35 /40 [87.5 %]; P = 0.10, OR 0.39 95 %CI 0.11 - 1.15). Capsule endoscopy reached the duodenum in 45 /46 patients (98 %). One patient (2.2 %) had self-limited shortness of breath and one (2.2 %) had coughing on capsule ingestion.

CONCLUSIONS

In an emergency department setting, capsule endoscopy appears feasible and safe in people presenting with acute upper gastrointestinal hemorrhage. Capsule endoscopy identifies gross blood in the upper gastrointestinal tract, including the duodenum, significantly more often than nasogastric tube aspiration and identifies inflammatory lesions, as well as EGD. Capsule endoscopy may facilitate patient triage and earlier endoscopy, but should not be considered a substitute for EGD.

The use of Pillcam Colon in assessing mucosal inflammation in ulcerative colitis: a multicenter study

BACKGROUND AND STUDY AIM

Treatment of ulcerative colitis should be tailored to the severity of colonic inflammation, which in the past has been gauged mainly by clinical features and biochemical parameters. Recently, mucosal healing has been proposed as a standard to guide therapy. The aim of this multicenter study was to test whether mucosal appearance, as reported by colon capsule endoscopy (CCE), can be used to differentiate active from inactive ulcerative colitis.

PATIENTS AND METHODS

Adult patients from Hong Kong, Singapore, and Taiwan who were suspected or known to have ulcerative colitis were included in this prospective study. CCE and conventional optical colonoscopy were offered to these patients on the same day after receiving standard bowel preparation. The primary endpoint was the accuracy of CCE in assessing colonic inflammation (defined as the presence of ulcers, erythema, erosions, edema, exudates in mucosa), using optical colonoscopy as the gold standard.

RESULTS

At total of 100 patients (42 females; median age 50 years; range 22 - 68 years) were enrolled. Four cases were excluded from the analysis due to technical failure or slow transit of the capsule. In nine patients, the capsule was not excreted within 8.5 hours and required retrieval during colonoscopy. The sensitivity of CCE to detect active colonic inflammation was 89 % (95 % confidence interval [CI] 80 - 95) and specificity was 75 % (95 %CI 51 - 90). The positive and negative predictive values of CCE for colonic inflammation were 93 % (95 %CI 84 - 97) and 65 % (95 %CI 43 - 83), respectively. No serious adverse event related to the CCE procedure or preparation was reported.

CONCLUSION

CCE is a safe procedure to monitor mucosal healing in ulcerative colitis. However, at this stage, CCE cannot be recommended to replace conventional colonoscopy in the management of this condition.

Fine particles and meteorological conditions are associated with lung function in children with asthma living near two power plants

Fine particles are thought to pose a risk to health, especially for vulnerable groups such as children with asthma. These children are also known to be affected by meteorological and seasonal changes. We assessed the association between air pollution and lung function via peak expiratory flow (PEF), controlling for seasonal changes, meteorological conditions and personal physiological, clinical and sociodemographic measurements, in a panel of schoolchildren with asthma living near two power plants in Israel. Two hundred and eighty-five children with confirmed asthma performed PEF tests and completed a respiratory symptoms diary twice a day. Particulate matter <10 microm in diameter (PM10), particulate matter <2.5 microm in diameter (PM2.5) and meteorological conditions were measured at six fixed stations. Data were analysed using time series analysis-generalized linear model and generalized estimating equations. The models were built under the assumption that any health outcome belongs to a multivariate hierarchical system and depends on meteorological, geophysical and sociocultural variables and pollution factors. No significant differences were found in the demographic (age, gender, mean parental education level, parental smoking habits, place of birth and housing density), physiological (body mass index) and clinical factors (illness severity) between the communities participating in the study. A significant direct effect of PM2.5 on the PEF was found in Ashdod (P=0.000). In Sderot, this effect was through an interaction between PM10 and the sequential day of the year (P=0.000). The main conclusion of this study is that children with asthma are at risk from air pollution and geophysical conditions. Policy makers should take these results into consideration when setting thresholds for environmental protection.

The significance of the degree of myometrial invasion in patients with stage IB endometrial cancer

OBJECTIVE

To study the validity of the FIGO staging classification of endometrial cancer Stage IB by correlating degree of myometrial invasion depth with outcome measures.

STUDY DESIGN

Fifty patients with endometrial adenocarcinoma FIGO Stage IB who underwent hysterectomy between 1989 and 2001 were divided into two groups according to depth of myometrial invasion. The first group comprised of 31 patients with myometrial invasion of less than or equal to one-third. The second group included 19 patients with invasion greater than one-third but less than one-half. The two groups were compared with regard to prognostic factors and outcome measures.

RESULTS

The overall 5-year recurrence-free survival, disease specific survival and overall survival rates were 87%, 94% and 77%, respectively. These outcome measures did not vary significantly between the two groups. There were no statistically significant differences between the two groups with regard to the following parameters: duration of follow-up, age, proportion of patients who underwent complete surgical staging and postoperative adjuvant radiotherapy. Histologic parameters of the two groups, such as histological type, grade and proportion of patients with capillary space-like involvement and lower uterine segment involvement were not significantly different.

CONCLUSIONS

In patients with Stage IB endometrial cancer the amount of myometrial invasion defined as less than one third compared with invasion greater than one third does not appear to correlate with their outcome, thus validating the FIGO staging system.

Colour Doppler ultrasonography for detecting perineural invasion (PNI) and the value of PNI in predicting final pathological stage: a prospective study of men with clinically localized prostate cancer

OBJECTIVES

To assess the ability of colour Doppler transrectal ultrasonography (CD-TRUS) to improve the accuracy of detecting perineural invasion (PNI, reported to be an independent predictor of extraprostatic extension) and in predicting the pathological stage of the cancer, comparing it with the results of grey-scale TRUS-guided biopsies.

PATIENTS AND METHODS

This prospective study included 47 men with clinically localized disease; all underwent 10-core TRUS-guided biopsy and two bilateral CD-TRUS-guided biopsies, targeted on the area adjacent to the neurovascular bundle. The rates and accuracy of PNI detection on 10-core and CD-TRUS-targeted biopsies were compared with the pathological outcome. Various patient, clinical and pathological factors were compared, and multivariate analysis used to assess the value of the technique in predicting PNI and pathological outcome.

RESULTS

CD-TRUS-guided biopsies predicted the presence of PNI in the radical prostatectomy specimens with a sensitivity of 89%, and specificity and positive predictive values of 100%. Seven of 24 (29%) patients with PNI on the needle biopsies had pT3 disease. Conversely, the absence of PNI on guided biopsy accurately predicted pathologically localized disease in 96% (negative predictive value) of patients. However, the results of multivariate analysis showed that serum prostate-specific antigen was the only strong predictor of pT3.

CONCLUSION

CD-TRUS is a useful tool for detecting PNI and predicting pathological localized cancer; it can be used in candidates for nerve-sparing radical prostatectomy.

Clinical and polysomnographic characteristics of 34 patients with Kleine-Levin syndrome

There is only scant information on sleep characteristics and long-term follow-up in patients with Kleine-Levin syndrome (KLS). This study describes the clinical course, results of polysomnography and long-term follow-up in a relatively large group of patients with KLS. During the years 1982-97, we encountered 34 patients (26 males and eight females) with KLS. We were able to obtain the original polysomnographs from 28 males and four females. In 25 patients, data regarding their present state of health were obtained. Fourteen agreed to be present at a detailed interview and examination while 11 gave the information by phone. The mean age at onset was 15.8 +/- 2.8 years and the mean diagnostic delay, 3.8 +/- 4.2 years. The mean duration of a single hypersomnolent attack was 11.5 +/- 6.6 days. The main abnormal findings extracted out of 35 polysomnographs obtained from 32 patients during and/or in-between attacks included: decreased sleep efficiency, and frequent awakenings from sleep stage 2. All 25 patients reported present perfect health, with no evidence of behavioral or endocrine dysfunction. In adolescents with periodic hypersomnia, the diagnosis of KLS should be explored. Sleep recordings during a hypersomnolent period will often show frequent awakenings from sleep stage 2. The long-term prognosis is excellent.

The effects of maternal and fetal parameters on the quality of nuchal translucency measurement

OBJECTIVE

To evaluate the influence of maternal and fetal parameters on the quality of fetal nuchal translucency measurement.

DESIGN

This was a prospective study in 227 consecutive pregnant women undergoing nuchal translucency screening by transabdominal sonography. The same well-qualified sonographer performed all the scans and in each case the best-quality image was selected and scored according to an image scoring system (total maximum score, 9). The quality of the image was examined in relation to maternal age, weight, abdominal wall thickness, amniotic sac diameter, posterior uterine wall depth (distance between abdominal wall surface and posterior uterine wall surface), placental location, fetal crown-rump length and nuchal translucency thickness. Correlation coefficients were calculated and stepwise linear regression was used to adjust for confounders and to define the predictors for image score.

RESULTS

The only two parameters that provided a significant independent contribution to the prediction of the image score were posterior uterine wall depth and fetal crown-rump length. Intravariable analysis of these two parameters demonstrated that the cut-off associated with a significant change in the image quality was 80 mm for posterior uterine wall depth (score difference, 1.06; P < 0.001) and 70 mm for crown-rump length (score difference, 0.77; P = 0.001). In the group of women with two values above these cut-off points, an average score decrease of 1.90 (P < 0.001) was observed.

CONCLUSIONS

The quality of fetal nuchal translucency measurement is poorer when the fetal crown-rump length is > 70 mm and the posterior uterine wall depth is > 80 mm.

The prescription pattern of oral nitrates in coronary artery disease. Appropriateness and cost considerations

OBJECTIVES

To evaluate the prescription patterns of oral nitrates in terms of appropriateness and cost in a community setting.

METHODS

A period prevalence, descriptive, applied study. Data including age, gender, type of medication, dosage and cost were extracted from the database of the largest health maintenance organisation (HMO) in Israel. The study population included enrollees over 35 years of age who received oral nitrates at least once during the 12-month study period.

RESULTS

Oral nitrates were prescribed for 8007 patients (mean age 72.85+/-9.59 years, male:female ratio 1:1). A total of 52,694 prescriptions were issued for 56,553 medications, of these 88.1% for mononitrates, which constituted 95% of the annual cost for patients and the HMO. The mean prescribed daily dose for the various drugs ranged from 30% less than to 50% more than the recommended dose. Combination therapy with at least two nitrates, which is not the recommended treatment, was given to 5% of the patients. The recommended alternative treatment will alleviate the financial burden for providers and patients.

CONCLUSIONS

Improved prescription habits can provide enhanced quality as well as cost savings for patients and providers.

Quality assurance of nurse triage: consistency of results over three years

The study objective was to evaluate the capability and the consistency of the triage nurse to categorize correctly emergency patients and its impact on the waiting time for physician examination over a period of 3 years. The study was performed at the emergency department of the Barzilai Medical Center, Ashkelon, Israel. A retrospective review of the medical records was performed. All patients who were examined by a triage nurse during 2 randomly chosen consecutive weeks during the years 1995 and 1998 participated. All the medical records were reviewed by the authors and the following information was extracted from the medical records: nurse triage category, time of initial evaluation by a triage nurse, duration of employment of the nurse in the ED, and her experience as a triage nurse, time of initial examination by a physician, the total length of stay in the ED, the history taken by the triage nurse and the physician, and the physician's urgency category. Patient in urgency category 1 is a patient whose condition may deteriorate if not examined within 1 hour; patient in category 2 is a patient whose condition may deteriorate if not examined within 2 hours; category 3 is all the rest. Any deterioration and or delay of treatment of the patients were also recorded. Data concerning patients with an initial complaint of chest pain were extracted separately. The data were analyzed using the SPSS software and the results were tested by the student t test and chi square test. Interobserver agreement was measured using the kappa value. A total of 2,886 completely full medical records were reviewed by the authors: 1,310 records from period I (1995) and 1576 from period II (1998). Of the patients 92% and 88.2% were classified by the triage nurse as category 3 in periods I and II respectively, 7% and 9.8% as category 2, and 1% and 2% as category 1 respectively. Full agreement of triage category between nurse and physician was found in 90.5% of the cases in period I and 93% in period II (kappa = 0.90 and kappa = 0.93 respectively). In period I, 70% of the patients in category 1 were examined by a physician in 1 hour versus 100% in period II. Almost all the patients in category 2 were examined within 2 hours (98%, 97%), and 98% of those in category 3 were examined within 3 hours. The average waiting time for physician examination in category 1 patients dropped from 43.1 minutes in period I to 18.2 minutes in period II. The average waiting time for the triage nurse was 9 minutes in period I, and 7.42 minutes in period II. The average length of stay in the ED in period I was 1 hour and 24 minutes and 1 hour and 30 minutes in period II. Of the anamneses taken by the triage nurse 91.8% were fully identical with the physicians' anamneses, but in period II this percentage jumped to 98%. Patients with chest pain were categorized correctly by the triage nurse in 76.8% of the cases in period I and 72.4% in period II, with an overtriage of 18.6% and 20.7% respectively (kappa = 0.75, kappa = 0.70 respectively). In our study, nurse triage was safe and effective in classifying patients to urgency categories. The results are consistent and even improved over a 3-year period. The rates of incorrect classification, deterioration, and delay of treatment of patients because of incorrect triage are very low. Most of the patients were examined by the physician within the expected time. Triage nurse predicted correctly the urgency category of patients with chest in most of the cases and the rate of missing acute coronary events was very low.

Increased incidence of diabetes mellitus in the patients with transitional cell carcinoma of urinary bladder

The progression of bladder cancer to invasive disease is highly dependent on its ability to penetrate basement membrane of urothelium. Studies on diabetic nephropathy have shown a reduction in proteoglycan content of the glomerular basement membrane. Based on the well-known fact that proteoglycans are one of the main components of basement membrane and extracellular matrix we assessed the relationship between diabetes mellitus, bladder cancer incidence and its behavior. These studies include 252 patients with microscopically confirmed transitional cell carcinoma of bladder, and 549 patients with other urological disorders who served as controls. The prevalence of diabetes mellitus in each group was assessed. The group of patients suffering from transitional cell carcinoma was divided according to etiological risk factors such as cigarette smoking, diabetes and patients that were non-smokers and did not suffer from diabetes mellitus. We assessed the features of bladder cancer behavior in each group. Logistic regression model estimation for statistical analysis was used, with transitional cell carcinoma as a dependent binary variable and age, sexes smoking and diabetes as independent variables. Statistical significance was considered at two levels: p <or=0.001 and p <or=0.05. Odds ratio (OR) adjusted to age, sex, cigarette smoking, diabetes mellitus and 95% Confidence Interval (CI) were calculated for TCC. In the TCC group 22.2% of the patients suffered from diabetes mellitus. In the control group 10.38% suffered from diabetes mellitus. Logistic regression analysis, OR and 95% CI showed a statistically significant relationship between diabetes and TCC. These data are comparable only with smoking (OR 2.3; 95% CI 1.6 3.5 and OR 1.58; 95% CI 1.08 2.4 correspondingly). Based on these data we suggest that diabetes mellitus may be considered an etiological risk factor for bladder cancer development.

Differences in lung function among school children in communities in Israel

Differences in lung functions of school-age children who lived near two electrical power plants in the Ashkelon district of Israel were studied. Lung-function tests were performed, and the American Thoracic Society questionnaire was administered in three study periods during the following years: (1) 1990, (2) 1994, and (3) 1997. Measurements of air pollutants (i.e., sulfur dioxide, nitric oxides, ozone) were also taken during the aforementioned study periods. Statistical analysis included an estimation of a series of fixed-effects regression models. A total of 2,455, 1,613, and 4,346 observations were included in the analyses for study years 1990, 1994, and 1997, respectively. The authors controlled for age, sex, height, weight, parents' education and smoking status, and being born out of Israel, and, consequently, substantial differences in lung function across the different communities and study periods were demonstrated in the study area. No robust association with air pollution was demonstrated. The cause of these differences in the respiratory health of children remains unknown.

Kleine Levin syndrome (KLS) in young females

During the years 1982-1998, we encountered 7 adolescents and one young woman suffering from KLS. In 4 patients, hypersomnolence was accompanied by hyperphagia and hypersexuality, while in the remaining 4, recurrent hypersomnia was the only symptom. Mean age at onset of hypersomnolent attacks was 15.1+/-3.5 yrs. The mean duration of a hypersomnolent attack was 9.9+/-5.4 days, and the number of attacks per patient was 6.2+/-3.4. Polysomnographic recordings from 3 patients inbetween attacks, and from one patient during an attack, showed relatively normal sleep structure with decreased sleep efficiency due to numerous awakenings from sleep stage 2. Besides the recurrent hypersomnia, all patients enjoyed good health, with no evidence of behavioral or endocrine dysfunction. Similarly aged males with KLS from our clinic and previously reported females, had similar clinical features.

Prior antihypertensive treatment and admission blood pressure correlated with clinical outcome and early morning presentation in hypertensive ischaemic stroke patients

Blood pressure (BP) reduction of 5-6 mm Hg reduces the relative risk of stroke by 30-40%. This effect does not appear to depend on the antihypertensive agent used to bring about the required reduction in BP. Patients with acute ischaemic stroke often exhibit an elevated BP. These patients, who previously suffered from hypertension, have significantly higher levels of BP readings on admission with increased incidence of stroke immediately after arising. The aim of this study was to compare antihypertensive agents, especially short and long acting drugs with the measurement of BP on admission, the time of the ischaemic stroke and its clinical severity. This was studied retrospectively in 109 patients (55 females and 54 males). The mean age was 69.7 +/- 10.4 years. All the patients admitted between 1 July 1996 and 30 June 1997 for ischaemic stroke as established by brain CT scan, were studied. Of the stroke subjects not treated or treated with short acting calcium blockers, 40.8% and 44.4% of them respectively appeared to have an ischaemic stroke in the early morning hours in contrast to 20% of those treated with long acting calcium blockers (P < 0.05). The last group of patients also experienced less clinical severity. These results emphasise the need for proper 24-h control of BP and by comparison to other antihypertensive agents, the long acting calcium blockers with these subjects may prevent a sudden early morning rise in BP, which is instrumental in stroke prevention.

[Violence in the emergency department]

There is an international epidemic of violence in the emergency department (ED) which threatens medical staff daily. The problem is underestimated in Israel and there are as yet no regulations of the Ministry of Health and the Bureau of Security and Safety that deal with the problem. At the beginning of 1997 we conducted a retrospective survey to estimate the extent of this problem and to define its causes and the various options for management. An anonymous questionnaire was given to all permanent workers of our ED: physicians, nurses and reception clerks, as well as physicians who worked in the ED during evening and night shifts at least twice a week. 74% of (questionnaire) responders experienced violent events, most of them 5 or more times during the previous 2 years. Violence was experienced by 90% of nurses, 70% of physicians and 64% of clerks. The main reason for violence was prolonged waiting in the ED. Other causes were dissatisfaction with treatment, refusal to leave the ED, and language that displeased the patient. Most violent patients were middle-aged men, of whom alcohol and drug users were only a small proportion. Most victims of physical violence called hospital security personnel, but only a third of the victims of verbal violence pressed charges. Half of the staff who were physically attacked called the police and most pressed charges. Only 2 attackers were convicted; charges were dropped against 3 because of "lack of public concern." We were unable to ascertain the results of the other charges. Most victims of violence didn't press charges because of fear resulting from threats of the patient and/or family. The violent patient was usually characterized by responders as a middle-aged man, sober, of low socioeconomic level, impatient, with a bad previous hospital experience, dissatisfied with treatment and who insisted on being admitted to hospital. Suggestions for violence management by questionnaire-responders included 24-hour police protection and a training program in violence management for hospital security and medical staff.

[Recording nocturnal erections following injuries and insurance claims: cost-effectiveness]

Road accidents, work accidents, or other trauma can cause impotence and are frequently followed by insurance claims. During 1990-97 we examined 230 males with such a complaint. All underwent full polysomnographic recordings in the sleep laboratory for 2 nights, during the course of which NPT (nocturnal penile tumescence) was examined with special equipment. It was assessed by an experienced technician following planned awakenings from REM sleep. In 75 of the 230 subjects (33%), satisfactory erections were observed. In 100 (43%), who experienced at least 3 periods of REM sleep, no erections occurred. These patients were categorized as suffering from organic impotence. In the remaining 55 (24%), the results were inconclusive, with only partial erections or not enough REM sleep periods. Since a man recognized as suffering from impotence may be awarded large monthly payments for life, these examinations, in our opinion, are an important tool to prevent unjustified claims, and can save the state unnecessary expenses.

[Investigating chest pain--is there a gender bias?]

Ischemic heart disease (IHD) is women is characterized by a higher morbidity and mortality in the peri-infarction and coronary bypass peri-operative periods. These epidemiological data strengthen our impression that the health system unintentionally "ignores" the high proportion of females with IHD. The process of investigating chest pain, diagnosing IHD, and the subsequent treatment and rehabilitation, seem to differ between the genders. Time elapsed from beginning of chest pain to diagnosis of IHD seems to be longer in women than in men. Personal, educational and social factors are contributory. Although time elapsed between diagnosis and rehabilitation is usually similar in the genders, peri-operative morbidity and mortality are higher in women. It may be that the higher rates in women are caused by delay in diagnosis and treatment, which allows worsening of the disease in women before treatment. This delay can occur during the time needed for evaluation of chest pain, from the door of the physician to diagnosis and treatment. In our retrospective study we determined the difference in referral of men and women with chest pain to the emergency department (ED) and the attitude of physicians in the ED and medical department to chest pain in men and in women, including final diagnosis on discharge. 615 patients over 18 years referred to the ED for chest pain during 3 randomly chosen, consecutive months were studied. We found that women constituted only 39.5% of the referred patients, but the proportion hospitalized was similar to that in men. Hospitalized women were older (57.7 +/- 18.4 versus 49.7 +/- 17.8 years in men), and had more risk factors (4 versus 2 in men). Proportions of specific diagnoses on discharge from hospital were equal in the genders. To bridge the differences and to implement education in prevention, investigation and treatment of IHD in women, we established the "Female Heart" clinic. The objective of this clinic is to reduce differences in the first step, in the process of evaluating chest pain in women, by educating and encouraging them to present early to their physicians, and by changing physicians' attitudes in the investigation of chest pain in women. We plan to determine in a prospective study if these goals are reached.

[Has the health profile and pregnant Ethiopian immigrants changed in the Ashkelon region in the past years?]

There are about 6500 births yearly in the Ashkelon District. 6% of the mothers are Ethiopians, most of whom immigrated to Israel since the early 90's. Our data are from 3 sources: birth certificates, infant death certificates, and the national population register. Birth rates in single mothers and rates of low-birth-weight births have declined over the years. Infant mortality and still-birth rates have also shown remarkable and consistent declines between 1990-1995. We conclude that improvement in life conditions of Ethiopian immigrants and better use of health services have had a great impact on birth outcomes and pregnancy patterns. The gap between Ethiopian immigrants and other Jewish communities in Israel is closing fast.

Epidemiology of childhood tuberculosis in the Ashkelon region in Israel, 1958-1994

The incidence rates of tuberculosis (TB) in Israel decreased steadily up to 1984, but rose again between 1985 and 1991, mainly due to immigration waves from Ethiopia. The epidemiology of TB in children was surveyed in the Ashkelon region. The regional TB register of Barzilai Medical Centre, kept since 1958, was used as the source for our data. Two hundred and fifty TB cases in children were reported between 1958 and 1994, constituting 9.7% of the total 2565 cases reported in the whole population of Israel's southern Mediterranean coast. While in the late 1950s and early 1960s the majority of reported cases occurred in children of North African origin, reflecting the large wave of immigration from North Africa at that time, in 1985-94 at the time of the Ethiopian immigration wave, Ethiopian children constituted the majority of the patients. They were diagnosed up to 9 years after arrival. None of the reported cases was HIV-positive.

Surgical treatment of sleep apnea syndrome

Several surgical procedures have been developed for the treatment of sleep apnea syndrome. These include nasal, uvulopalatopharyngeal, and head and neck surgery, weight reduction surgery, and tracheostomy. Despite over 15 years of experience with some of these operations, there is still a lack of consensus regarding the indications, success rate, complications, and long-term prognosis associated with these procedures. The current status of these surgical procedures is reviewed.

Reversible surface aggregation in pore formation by pardaxin

The mechanism of leakage induced by surface active peptides is not yet fully understood. To gain insight into the molecular events underlying this process, the leakage induced by the peptide pardaxin from phosphatidylcholine/ phosphatidylserine/cholesterol large unilamellar vesicles was studied by monitoring the rate and extent of dye release and by theoretical modeling. The leakage occurred by an all-or-none mechanism: vesicles either leaked or retained all of their contents. We further developed a mathematical model that includes the assumption that certain peptides become incorporated into the vesicle bilayer and aggregate to form a pore. The current experimental results can be explained by the model only if the surface aggregation of the peptide is reversible. Considering this reversibility, the model can explain the final extents of calcein leakage for lipid/peptide ratios of > 2000:1 to 25:1 by assuming that only a fraction of the bound peptide forms pores consisting of M = 6 +/- 3 peptides. Interestingly, less leakage occurred at 43 degrees C, than at 30 degrees C, although peptide partitioning into the bilayer was enhanced upon elevation of the temperature. We deduced that the increased leakage at 30 degrees C was due to an increase in the extent of reversible surface aggregation at the lower temperature. Experiments employing fluorescein-labeled pardaxin demonstrated reversible aggregation of the peptide in suspension and within the membrane, and exchange of the peptide between liposomes. In summary, our experimental and theoretical results support reversible surface aggregation as the mechanism of pore formation by pardaxin.

HLA class II analysis in Jewish Israeli narcoleptic patients

HLA class II was investigated in eight Jewish narcoleptic patients, representing the total of such patients known in Israel at present, and in three patients suffering from sleep disturbances other than narcolepsy. All (11 out of 11) patients carried the serologic specificities DR2, DQ6 (DQ1). At the DNA level, all narcoleptics were found to be DRB1*1501, DQA1*0102, DQB1*0602 which indicates that the susceptibility gene may be located within the HLA class II region, DR, and/or DQ. As for the nonnarcoleptic patients with idiopathic hypersomnia, they carried different alleles of DR2 and DQ6, namely DRB1*1502, DQA1*0103, DQB1*0601. This study confirms that the incidence of narcolepsy in Israel is extremely low and that HLA class II genes or a gene(s) tightly linked to them are involved in the disease.

[Treatment of obstructive sleep apnea with anterior mandibular positioning device]

The efficacy of the anterior mandibular positioning (AMP) device in obstructive sleep apnea syndrome was assessed. This device advances the mandible anteriorly by approximately 5-7 mm. 29 patients were examined and questioned about temporomandibular (TM) and facial pain before and after treatment with the device. Polysomnographic sleep studies were performed on all before, and 2 weeks after continuous use of the AMP device. 10 of the patients also underwent polysomnographic follow-up after 1 year. The mean apnea index (AI) before treatment was 40.1, which decreased to 24.3 (p < 0.0001) after 14.3 days of treatment with the AMP device. O2 saturation also increased, from 84.2% before, to 89.2% after treatment (p < 0.002). In 10 patients the mean AI after 1 year was 24.9, not different from that after only 2 weeks of treatment, but significantly different from their mean AI before treatment (39.8). Use of the AMP device did not change blood saturation levels; neither did it affect dental status, action of the masticatory muscles, nor did it cause TM joint dysfunction. 21 patients (72.4%) have now been fitted with an AMP device, and the mean follow-up is 13.4 months (range 2-22); 3 have been using the AMP only intermittently for TM joint pain or discomfort. We conclude that the AMP device helps the majority of patients and is an alternative, nonsurgical method for treating obstructive sleep apnea syndrome.

Mortality in sleep apnea patients: a multivariate analysis of risk factors

During 1976-1988 we diagnosed sleep apnea syndrome (SAS) in 1,620 adult men and women monitored in the Technion sleep laboratories. Their age at the time of diagnosis ranged between 21 and 79 years. Fifty-seven patients (53 men and 4 women) had died by 1990, 53% due to respiratory-cardiovascular causes. The observed/expected (O/E) mortality rates, calculated for men only, revealed excess mortality of patients under 70 years old. Excess mortality was significant in the fourth and fifth decades (3.33, p < 0.002; 3.23, p < 0.0002, respectively). In patients older than 70 O/E was 0.33 (p < 0.0007). Hierarchical multivariate analysis with four fixed variables [age, body mass index (BMI), hypertension and apnea index] and four additional variables added manually one at a time (heart disease, lung disease, diabetes, apnea duration) was used to determine the predictors of death from all causes, cardiopulmonary causes and from myocardial infarction (MI). All four major variables were found to be significant predictors of mortality from all causes, in addition to lung disease and heart disease. Only age and BMI were significant predictors of cardiopulmonary deaths in addition to lung disease. Age, BMI and hypertension predicted MI deaths in addition to lung disease. These results were interpreted to suggest that SAS affects death indirectly, most probably by being a risk factor for hypertension.

Melatonin improves evening napping

Twelve young adults were treated with either melatonin, 3 mg or 6 mg, or placebo, at two different times before an early evening nap (18.00-20.00 h) according to a balanced double-blind Latin square design. Polysomnographic monitoring revealed that both dosages of melatonin significantly shortened sleep latency and increased total sleep time in comparison to placebo, irrespective of the time of administration. Subjects also tended to assess their sleep as 'deeper' after melatonin treatment. Based on previous data and the present results, it was concluded that exogenous melatonin exerts hypnotic effects only when circulating levels of endogenous melatonin are low.

Recurrence of sleep apnea without concomitant weight increase 7.5 years after weight reduction surgery

In this study we report on a long-term follow-up of 14 morbidly obese sleep apneic patients, 11 of whom were male and 3 female. The mean age was 46 +/- 8.5 years. These patients had undergone weight reduction surgery. Before surgery, body mass index (BMI) and apnea index (AI) were 45 +/- 7.2 kg/m2 and 40 +/- 28.8 (SD) h-1, respectively. Four and a half months after surgery (range, 2 to 7 months), both BMI and AI significantly decreased to 33 +/- 7.5 kg/m2 and 11 +/- 16.4 h-1, respectively. Seven and half years after surgery (range, 5 to 10 years), BMI increased only slightly to 35 +/- 6.0 kg/m2 (p > 0.2), while AI increased significantly to 24 +/- 23 h-1 (p < 0.05). There were poor and insignificant correlations between changes in BMI and AI prior to 4.5 months after operation (r = 0.23; p > 0.4). and 4.5 months to 7.5 years after operation (r = 0.41; p > 0.1). We conclude that morbid obesity is not the only causative factor in the sleep apnea syndrome for these patients. Weight reduction surgery alone does not "cure" their sleep apnea, and they are still at risk.

[Ambulatory blood pressure in obstructive sleep apnea syndrome]

38 patients with obstructive sleep apnea syndrome underwent automated ambulatory 24-hour blood pressure monitoring. Systolic, diastolic and mean pressure values were significantly correlated with the apnea index (AI) during sleep, as well as during wakefulness. A significant negative correlation was found between minimal arterial O2 saturation in sleep and diastolic blood pressure values during waking hours. The contribution of the AI to blood pressure during sleep and wakefulness was significant, while the contribution of body mass index (BMI) was negligible. These results support the causal relationship between the severity of sleep apnea syndrome and systemic hypertension, independent of BMI.

The relationship between the severity of sleep apnea syndrome and 24-h blood pressure values in patients with obstructive sleep apnea

Automated ambulatory 24-h BP monitoring was made in 38 patients with obstructive sleep apnea syndrome. Stepwise multiple regression analysis revealed that diastolic, systolic, and mean BP values during sleep as well as during wakefulness were significantly related to apnea/hypopnea index and age. Minimal arterial O2 saturation and total sleep time also significantly contributed to diastolic and mean BP values during sleep. Body mass index did not significantly contribute to any of the BP values. These results support a causal relationship between the severity of sleep apnea syndrome and systemic hypertension.

Bariatric surgery in morbidly obese sleep-apnea patients: short- and long-term follow-up

Forty-seven obese sleep-apnea patients were investigated in the sleep laboratory before and after a massive weight reduction achieved by bariatric surgery. The first postoperative sleep investigations were performed approximately 1 y after surgery and revealed a highly significant decrease in the number of apneic episodes per hour of sleep and a significant improvement in all sleep-quality-related measures. A second postoperative sleep study was performed approximately 7 y postoperatively and revealed that regaining of weight was associated with the reappearance of sleep apnea syndrome, although the great majority of the patients still felt, subjectively, that they were well and did not suffer from recurrence of the sleep apnea syndrome.

The value of sleep recording in evaluating somnambulism in young adults

Somnambulism (SOM) is a benign childhood sleep disorder which may persist until young adulthood. The diagnosis relies heavily on the history, and no polysomnographic (PSG) criteria have yet been defined. The present study attempts to evaluate the role of whole-night polysomnographic recording in the investigation of SOM. The PSG records of 24 sleepwalkers, 18-25 years old, and 12 age-matched controls, were analysed. Sleepwalkers had remarkably more epochs containing hypersynchronous delta waves (HSD) (59.6 +/- 60.1 vs. 1.7 +/- 3.2; P less than 0.0001), a higher proportion of HSD/total time spent in stage 3-4 (24.9 +/- 21.1% vs. 1.1 +/- 2.0%, P less than 0.0002), and more stage 3-4 sleep interruptions (8.4 +/- 5.7 vs. 3.7 +/- 1.7, P less than 0.004). They also tended to have a larger proportion of their sleep time in stage 3-4 (30.6 +/- 11.7% vs. 22.6 +/- 6.8%; P less than 0.07). Although their sensitivity and specificity have yet to be more fully investigated, these seem to be quantitative, easy-to-use variables which may characterize adult SOM and may aid in its proper diagnosis.

[Obstructive sleep apnea treated with uvulopalato-pharyngoplasty]

38 patients with sleep apnea syndrome treated with uvulopalato-pharyngoplasty were interviewed 23 +/- 10.8 months after the operation (mean age 48.0 +/- 8.6 years, range 28-65). 22 were also studied in the sleep laboratory 10 +/- 10.7 months after operation. 3 months after operation 94% reported improvement in snoring and 77% improvement in excessive daytime sleepiness. 1 and 2 years after the operation snoring had decreased to 74% and 65%, respectively, and excessive sleepiness to 65%, for both periods. There was a decrease of at least 50% in the number of apneic periods per hour of sleep in 68%. Side-effects consisted of nasal regurgitation and vocal changes. Only age was of predictive value: the younger the patient the better the response.

Sleep paralysis: a study in family practice

Over a period of two years, five patients with sleep paralysis referred themselves to four family practices in Israel serving a population of 6800. None of the patients suffered from daytime sleep attacks or cataplexy and all were from the oriental (sephardi) community. The two who were tissue typed had HLA haplotypes different from those which are exclusively associated with narcolepsy and one of them who also underwent polysomnography had a normal tracing. There was considerable delay in consulting a physician despite the physical and mental anguish caused by the disorder and some improvement was noted once the diagnosis was explained. The serious nature of the components of the differential diagnosis - myocardial infarction, seizure disorder, cardiac arrest, anaesthetic accident - makes it important that sleep paralysis be more widely recognized.

Narcolepsy-cataplexy in Israeli Jews is associated exclusively with the HLA DR2 haplotype. A study at the serological and genomic level

Narcolepsy is a very rare disease among Israeli Jews with a frequency of 7/3 X 10(6). An investigation of the association of narcolepsy with the human leukocyte antigen system was conducted in Israeli Jews at the serologic and genomic levels. The human leukocyte antigen class I and class II antigen typing of 7 clinically diagnosed narcoleptics, 3 individuals suffering from sleep disorders other than narcolepsy, and 11 healthy matched controls revealed that all narcoleptic patients (100%) investigated in the present study carried the HLA-DR2 haplotype, whereas patients with other sleep disorders did not. The HLA-B7 and DR2 occurred jointly in 57% (4/7) of the narcoleptic patients, as compared to 2% in randomly selected Israeli healthy controls. Restriction fragment length polymorphism analysis was performed with several restriction enzymes and three cDNA probes for DQ alpha, DQ beta, and DR beta genes on genomic DNAs obtained from narcoleptics and patients with other sleep disorders, matched controls, and 3 homozygous typing cells representing the DR2 subtypes Dw2, Dw12, and DwAZH. The restriction fragment length polymorphism analysis showed that all narcoleptics (7 of 7) shared virtually identical restriction fragment length polymorphisms with one of the homozygous typing cells (GSO), which defines DR2,Dw2. The frequency of the DR2,Dw2 haplotype in the healthy Israeli population is 3.2%. Other non-narcoleptic patients did not share these restriction fragment length polymorphisms. These findings indicate that narcolepsy is associated worldwide with the HLA-DR2,Dw2 haplotype.

Double-blind evaluation of clonazepam on periodic leg movements in sleep

Treatment with clonazepam was studied in a group of 20 patients suffering from periodic movements in sleep, in a double-blind parallel group design. Eleven complained of excessive daytime sleepiness, and nine complained of insomnia. Ten patients received clonazepam, and 10 received placebo, over a period of 1 month. Clonazepam (0.5-2 mg per night) proved to be an effective treatment of periodic movements in sleep. Polysomnographic recordings demonstrated a significant decrease in the number of leg movements and a significant improvement in sleep parameters in the clonazepam group as compared with placebo. Subjective responses to treatment corroborated the sleep laboratory findings.

Agonist-like effects of the benzodiazepine receptor antagonist RO 15-1788

The present study investigated the effects of the benzodiazepine receptor antagonist RO 15-1788 on the ability to resist sleep after 1 night of sleep deprivation. Repeated administrations of RO 15-1788 to 6 subjects significantly decreased their ability to resist sleep in comparison with repeated administration of 100 mg of vitamin C, and with a nontreatment condition. Most of the hypnotic effect occurred 80-100 min after drug ingestion. RO 15-1788 also significantly enhanced sleep stage 2 spindles activity. These results demonstrate that at certain dosages RO 15-1788 has agonist-like effects.

Time domain analysis of VEPs. Detection of waveform abnormalities in multiple sclerosis

Visual evoked potentials (VEPs) are a useful tool in the diagnosis of multiple sclerosis. To improve their diagnostic power in the early stages of the disease, the VEP shape, as well as its latency, were considered. The Karhunen-Loeve expansion (KLE) was used because it affords an unique advantage in classifying the VEPs by their shape, and gives a well-defined criterion based on similarity to the normative prototype. Using this criterion, it was possible to quantitatively define normative limits of waveform. We were also able to detect early changes in VEPs recorded from suspected multiple sclerosis patients. KLE promises to enable classification of waveforms in early stages of the pathology, when peak-latency comparisons are the least effective.

Paroxysmal awakenings from sleep associated with excessive daytime somnolence: a form of nocturnal epilepsy

We describe 14 hypersomniac patients whose polysomnographic recordings revealed abnormal EEG patterns consisting of paroxysmal epileptic discharges during stages 2 and 3 of NREM sleep, associated with arousals, fragmentation of sleep, and reduction in sleep efficiency, particularly REM sleep. Three patients who received anticonvulsants showed clinical and polysomnographic documented improvement in sleep patterns. These patients probably had a unique form of nocturnal epilepsy-related sleep disorder, manifested by paroxysmal wakenings from sleep.

Preliminary clinical experience with imipramine HCl in the treatment of sleep apnea syndrome

In the last 2 years we have systematically treated 31 sleep apnea patients with 25-50 mg imipramine HCl given 30 min before bedtime. Imipramine treatment was attempted for nonoverweight patients with negative ear, nose and throat (ENT) findings and for patients who had not responded to weight reduction or ENT surgery (in all patients the apneas were not considered life threatening). Thirteen of the 31 (41.9%) patients, of whom 9 had central apnea, reported subjective improvement in diurnal and nocturnal symptoms within 10-15 days from the initiation of treatment. Sleep laboratory recordings conducted 1-5 months after the beginning of treatment revealed a significant decrease in the total number of apneas from 242 +/- 156 to 142.8 +/- 120.1 (p less than 0.01) in these patients. We concluded that treatment with imipramine may benefit selected sleep apnea patients particularly of the central type.

Periodic leg movements in sleep: effect of clonazepam treatment

Periodic leg movements in sleep were diagnosed in 8 patients with insomnia and in 12 patients with hypersomnia. Polysomnography did not reveal any difference in the number of leg movements in these groups, the mean duration of a leg movement, or the number of activity epochs. Those with insomnia, however, had a shorter intermovement interval than those with hypersomnia, with more leg movements in each activity epoch. Treatment with 0.5 to 2 mg clonazepam improved subjective complaints and decreased the number of leg movements without affecting the intermovement interval or movement duration.

A hypernychthemeral sleep-wake syndrome: a treatment attempt

The wake and sleep-onset times of a patient with a sleep-wake cycle longer than 24 hr were recorded by the patient for 4 years. During this time, the patient found himself unable to maintain a 24-hr sleep-wake schedule. When treated with 1-2 mg clonazepam, taken nightly, he was able to become entrained to a 24-hr day. Despite entrainment of his sleep-wake cycle, the patient reported depression, lack of motivation and fatigue and chose not to continue taking the drug.

Auditory middle latency-evoked potentials during sleep apnea

Auditory middle-latency evoked potentials (AMEP) were recorded in 10 subjects with predominantly central sleep apnea. AMEP were recorded during: waking; non-rapid eye movement (non-REM) sleep between apneic episodes; first half of apneas; and second half of apneas. Latencies of vertex positive peaks Po and Pa were determined, and the effect of the apnea phase on these latencies was evaluated. The latencies measured did not reveal chronic or acute functional abnormality of central auditory structures, which may result from or cause apneic episodes during non-REM sleep. The normalcy and stability of AMEP during apneic sleep may indicate effective compensatory mechanisms in central auditory structures. Alternatively, the lack of changes may result from the variability of AMEP, which may obscure small functional changes.