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Biomedical subjects

D S Silverberg

Publications and source records attributed to D S Silverberg.

At least 37 records · Page 2Linked to original sources
PubMed1997

Avoiding the supine position during sleep lowers 24 h blood pressure in obstructive sleep apnea (OSA) patients.

Obstructive sleep apnea (OSA), is a common clinical condition affecting at least 2-4% of the adult population. Hypertension is found in about half of all OSA patients, and about one-third of all patients with essential hypertension have OSA. There is growing evidence that successful treatment of OSA can reduce systemic blood pressure (BP). Body position appears to have an important influence on the incidence and severity of these sleep-related breathing disturbances. We have investigated the effect of avoiding the supine position during sleep for a 1 month period on systemic BP in 13 OSA patients (six hypertensives and seven normotensives) who by polysomnography (PSG) were found to have their sleep-related breathing disturbances mainly in the supine position. BP monitoring was performed by 24-h ambulatory BP measurements before and after a 1 month intervention period. We used a simple, inexpensive method for avoiding the supine posture during sleep, namely the tennis ball technique. Of the 13 patients, all had a reduction in 24-h mean BP (MBP). The mean 24-h systolic/diastolic (SBP/DBP) fell by 6.4/2.9 mm Hg, the mean awake SBP/DBP fell by 6.6/3.3 mm Hg and the mean sleeping SBP/DBP fell by 6.5/2.7 mm Hg, respectively. All these reductions were significant (at least P < 0.05) except for the sleeping DBP. The magnitude of the fall in SBP was significantly greater in the hypertensive than in the normotensive group for the 24 h period and for the awake hours. In addition, a significant reduction in BP variability and load were found. Since the majority of OSA patients have supine-related breathing abnormalities, and since about a third of all hypertensive patients have OSA, avoiding the supine position during sleep, if confirmed by future studies, could become a new non-pharmacological form of treatment for many hypertensive patients.

Adult↗
PubMed1997

Sleep-related breathing disturbances: their pathogenesis and potential interest to the nephrologist.

For about 120 years we have been looking for the 'cause' of essential hypertension. It is possible that we have merely been wandering through its graveyard, looking at the pathogenetic mechanisms but never the actual cause? Here we pass the gravestone of increased sympathetic activity; there the gravestone of low renin activity. Here high endothelin; there low EDRF. Here high thromboxane A2; there low prostacyclin. It is possible that all these and so many other pathogenetic factors are all due to one basic defect? Is it possible that, in the dead of night while patients with EH have been sleeping, the villain has been lurking in their mouths, stuck somewhere at the back of their throats, hidden from view yet choking them hundreds of times a night. But this intermittent strangulation has not occurred silently. On the contrary, it has made its presence felt in the most irritating way, with snores, groans, grunts, gasps and frightening periods of total apnea. But we, their physicians, never asked about these symptoms, or, if we did, we never paid heed to them. This is clear from the fact that, most cases of OSA occur in association with EH yet are not diagnosed. Perhaps the next 'arousal response' should be the arousal of physicians' consciousness so that they can at long last wake up to the existence of the close connection between sleep-related breathing disorders and hypertension and breathe some new life into the treatment of two old diseases-essential hypertension and secondary hypertension. Early diagnosis and treatment of the sleep-related breathing disorders may not only make the patient feel much better, (something our antihypertensive medications do not always do), but may reduce the blood pressure and prevent the progression of renal and cardiovascular damage as well.

Blood Pressure↗
PubMed1997

Positional vs nonpositional obstructive sleep apnea patients: anthropomorphic, nocturnal polysomnographic, and multiple sleep latency test data.

STUDY OBJECTIVES: To compare anthropomorphic, nocturnal polysomnographic (PSG), and multiple sleep latency test (MSLT) data between positional (PP) and nonpositional (NPP) obstructive sleep apnea (OSA) patients. DESIGN: This is a retrospective analysis of anthropomorphic, PSG, and MSLT data of a large group of OSA patients who underwent a complete PSG evaluation in our sleep disorders unit. The patients were divided in two groups: the PP group, those patients who had a supine respiratory disturbance index (RDI) that was at least two times higher than the lateral RDI, and the NPP group, those patients in whom the RDI in the supine position was less than twice that in the lateral position. SUBJECTS: From a group of 666 consecutive OSA patients whose conditions were diagnosed in our unit from September 1990 to February 1995, 574 patients met the following criteria and were included in the study: RDI > 10; age > 20 years, and body mass index (BMI) > 20. RESULTS: Of all 574 patients, 55.9% were found to be positional. No differences in height were observed but weight and BMI were significantly higher in the NPP group, these patients being on the average 6.5 kg heavier than those in the PP group. The PP group was, on average, 2 years younger than the NPP group. Nocturnal sleep quality was better preserved in the PP group. In this group, sleep efficiency and the percentages of deep sleep (stages 3 and 4) were significantly higher while the percentages of light sleep (stages 1 and 2) were significantly lower than in the NPP group. No differences for rapid eye movement (REM) sleep were found. In addition, wakefulness after sleep onset and the number of short arousals (< 15 s) were significantly lower in the PP group. Apnea index and total RDI were significantly higher and the minimal arterial oxygen saturation in REM and non-REM sleep was significantly lower in the NPP. No differences in periodic limb movements data were found between the two groups. The average MSLT was significantly shorter in the NPP group. Univariate and multivariate stepwise logistic regression analysis showed that the most dominant variable that correlates with positional dependency in OSA patients is RDI, followed by BMI which also adds a significant contribution to the prediction of positional dependency. Age, although significant, adds only a minor improvement to the prediction of this positional dependency phenomenon. A severe, obese, and older OSA patient is significantly less likely to be positional than a mild-moderate, thin, and young OSA patient. In four obese OSA patients who lost weight, a much more pronounced reduction was seen in the lateral RDI than in the supine RDI, and three of these cases who were previously NPP became PP. CONCLUSIONS: In a large population of OSA patients, most were found to have at least twice as many apneas/hypopneas in the supine than in the lateral position. These so-called "positional patients" are on the average thinner and younger than "nonpositional patients." They had fewer and less severe breathing abnormalities than the NPP group. Consequently their nocturnal sleep quality was better preserved and, according to MSLT data, they were less sleepy during daytime hours. RDI was the most dominant factor that could predict the positional dependency followed by BMI and age. RDI showed a threshold effect, the prevalence of PP in those with severe RDI (RDI > or = 40) was significantly lower than in those OSA patients with mild-moderate RDI. BMI showed a major significant inverse relationship with positional dependency, while age had only a minor although significant inverse relationship with it. Body position during sleep has a profound effect on the frequency and severity of breathing abnormalities in OSA patients.

Adult↗
PubMed1997

Essential hypertension and abnormal upper airway resistance during sleep.

The epidemiological, clinical, hereditary, biochemical, hematological, and physiological characteristics of essential hypertension (EH) and obstructive sleep apnea (OSA) are reviewed here. This extensive review shows that essential hypertension and sleep-disordered breathing--independently of whether it is OSA syndrome or upper airway resistance syndrome--share strikingly similar characteristics. The accumulated data obtained by many different researchers support the hypothesis that EH is mainly due to increased upper airway resistance during sleep. If this hypothesis is correct, treating disorders that cause increased upper airway resistance, particularly during sleep, would be an important part of the treatment of essential hypertension.

Age Factors↗
PubMed1996

Israeli preschoolers under Scud missile attacks. A developmental perspective on risk-modifying factors.

BACKGROUND: The devastating effects of traumatic events on children are modulated by risk and protective factors. This study examines the differential effects of traumatic displacement of preschool children and their families following Scud missile attacks on Israel during the Persian Gulf War. METHODS: Three groups participated in the study: families displaced after their houses were damaged, undisplaced families from the same neighborhood (without home damage), and families from a distant city that was threatened but not directly attacked. Data concerning the traumatic event, the child (personality, internalizing, externalizing, and stress symptoms), the mother (Symptom Checklist-90-Revised), and the family (Family Adaptability and Cohesion Evaluation Scales) were gathered 6 months after the end of the war. RESULTS: Displaced children and mothers showed higher externalizing and stress symptom levels compared with undisplaced and threatened subjects. Destruction of the house and displacement, but not mere distance from the missile impact, explained symptomatic behavior. Inadequate family cohesion predicted symptomatic reaction for 3- and 4-year-old children but not for older ones. CONCLUSION: Both human and nonhuman factors contribute to the preschool child's adaptive mechanisms that regulate environmental stressful stimuli. These risk-modifying factors become more autonomous of caretakers with increasing age.

Adaptation, Psychological↗
PubMed1996

Intravenous iron supplementation for the treatment of the anemia of moderate to severe chronic renal failure patients not receiving dialysis.

Iron deficiency may develop in hemodialysis patients, especially when erythropoietin is given. The role of iron deficiency in the anemia of predialysis chronic renal failure (CRF), however, is much less clear. We have intravenously (IV) administered iron as ferric saccharate in a total dose of 200 mg elemental iron monthly for 5 months to 33 CRF patients who remained anemic despite oral iron supplementation and who had no laboratory signs of iron overload. None was receiving erythropoietin therapy. In 22 of the patients there was an increase in the hematocrit values by the end of the study. These patients were considered responders to intravenous iron (IV Fe) therapy. In 11 patients the iron administration was not associated with improvement of the anemia (nonresponders). Before onset of the IV Fe therapy there were no differences between the responders and nonresponders with regard to degree of anemia, serum ferritin, iron saturation, renal function, or blood pressure. One additional patient was excluded from the study because of a mild reaction during an IV test dose before the study. No worsening of kidney function and no other side effects were noted. In four patients (three responders and one nonresponder) the control of blood pressure necessitated antihypertensive drug therapy adjustment. In conclusion, IV Fe supplementation in two thirds of anemic CRF patients not receiving dialysis resulted in a significant improvement of the anemia, thus avoiding the necessity of erythropoietin or blood administration. This could be achieved by increasing the plasma ferritin levels to 200 to 400 microns/L and/or increasing the iron saturation to 25% to 35%. Intravenous ferric saccharate appears to be a safe and effective method of administering iron for the correction of anemia in CRF patients not receiving dialysis.

Administration, Oral↗
PubMed1996

Nitric oxide in streptozotocin-induced diabetes mellitus in rats.

1. The present study was performed to determine the relationship between diabetic glomerular hyperfiltration and nitric oxide as modulated by the chronic administration of L-arginine and/or N-omega-nitro-L-arginine, a known nitric oxide synthase inhibitor in streptozotocin-induced diabetic rats. 2. Normal rats and rats drinking hypertonic glucose (10%) were used as time-controlled groups. Six weeks after administration of streptozotocin the diabetic rats had significantly higher creatinine clearance (667 +/- 53 microliters min-1 100 g-1 body weight) than before and streptozotocin (456 +/- 38 microliters min-1 100 g-1 body weight, P < 0.005) and very high plasma (37.8 +/- 10.9 mumol/l) and urinary (3.492 +/- 0.179 nmol min-1 100 g-1 body weight) nitrite+nitrate (stable metabolites of nitric oxide) values compared with before streptozotocin administration [19.3 +/- 2.8 mumol/l (P < 0.001) and 0.420 +/- 0.051 nmol min-1 100 g-1 body weight (P < 0.001) respectively]. The 6-week diabetic rats had higher systolic blood pressure (124.2 +/- 2.9 mmHg, P < 0.05) than before streptozotocin (108 +/- 8 mmHg), but had a value similar to that of the hypertonic-glucose-drinking rats. 3. The diabetic rats supplemented with L-arginine did not show an increase in creatinine clearance and had a lower urinary excretion of nitrite+nitrate (0.999 +/- 0.27 nmol min-1 100 g-1 body weight, P < 0.005) than the respective untreated streptozotocin-induced diabetic rats. Creatinine clearance increased in the normal and glucose-drinking rats that received L-arginine. The administration of L-arginine resulted in significant reduction in blood pressure in all groups studied. The chronic nitric oxide synthase inhibitor resulted in high blood pressure, and in a significant decrease in creatinine clearance and urinary nitrite+nitrate excretion in all groups studied. In both diabetic and glucose-drinking rats, the L-arginine therapy resulted in significantly lower plasma and urinary glucose levels than in their respective untreated control groups. 4. The nitric oxide synthase inhibitor increased the plasma and urinary glucose concentration in both diabetic and glucose-drinking rats. 5. Our results indicate that diabetic rats are characterized by high plasma concentrations and elevated urinary excretion of nitrite+nitrate, suggesting a state of high nitric oxide production. The vascular response to nitric oxide in diabetic rats may be different at the glomerular and peripheral vascular bed.

Alloxan↗
PubMed1996

Intravenous ferric saccharate as an iron supplement in dialysis patients.

In the present prospective study we examined the long-term effect of intravenous supplementation with ferric saccharate (IV Fe) in the treatment of the anemia of chronic dialysis patients. All patients, 64 on chronic hemodialysis (HD) and 9 on chronic ambulatory peritoneal dialysis (CAPD), were treated intravenously with this preparation in a dose of 100 mg elemental iron twice monthly. There were five groups. Group 1: 41 HD patients who were receiving erythropoietin (EPO) for at least 6 months prior to the addition of IV Fe. In this group, when IV Fe was given over 6 months, the hematocrit (Hct) increased from a mean of 28.7 to 33.7%. Over the next 6 months, the EPO dose was gradually reduced by a mean of 61.1%, but the mean Hct remained unchanged. Group 2: 11 HD patients who started IV EPO simultaneously with the IV Fe. In this group, over 6 months, the mean Hct increased from 28.1 to 34.1. Over the next 6 months, the EPO dose was gradually reduced by 75.7%, but the mean Hct remained unchanged. Group 3: 12 HD patients who received IV Fe alone for 12 months. The mean Hct increased from 30.5 to 37.9%. Group 4: 4 CAPD patients who had been receiving subcutaneous EPO for at least 6 months prior to IV Fe therapy. Over the subsequent 6 months of IV Fe, the mean Hct increased from 28.4 to 33.3%. Group 5: 5 CAPD patients not on EPO who received IV Fe for 6 months. The mean Hct increased from 27.7 to 35.6%. No adverse effects were seen in any patients throughout the study. In conclusion, adequate Fe supplementation may allow the target Hct of about 33% to be reached without, or with only very low doses of EPO. IV Fe as ferric saccharate is a new and safe form of parenteral iron therapy of the anemia of chronic dialysis patients.

Adult↗
PubMed1996

Essential and secondary hypertension and sleep-disordered breathing: a unifying hypothesis.

Obstructive sleep apnea (OSA) is a disorder in which there is repetitive collapse and closing of the pharynx during sleep. There is growing evidence to suggest that this disorder is a major cause of essential hypertension (EH) and that successful treatment of OSA can reduce the blood pressure (BP) significantly. In addition many other patients with EH have milder forms of sleep related breathing disorders (SRBD) like snoring, and upper airway resistance syndrome (UARS) which, while not as severe as OSA, may be severe enough to also cause systemic hypertension. We therefore propose a unifying hypothesis-that many patients with EH may have sleep related breathing disturbances (SRBD) and treatment of these disorders may improve the BP. SRBD could also explain many of the epidemiological, clinical, hereditary, biochemical, hematological and physiological characteristics seen in EH. In addition, many types of secondary hypertension (those caused by excessive alcohol intake, chronic renal failure, diabetes, hypothyroidism or acromegaly) have a higher than normal prevalence of OSA and OSA may contribute to the hypertension and organ damage found in these conditions as well. Thus SRBD may play an important role in the production of many cases of essential and secondary hypertension, and their early detection and treatment could reduce the hypertension and organ damage seen in these conditions.

Female↗
PubMed1996

Prescribing pattern of antihypertensive drugs in the community.

The selection of the most appropriate therapy for hypertension remains a controversial issue. Little information is available regarding the prescribing patterns of antihypertensives in the primary care setting in Israel. The use of antihypertensives in 200 patients of the Maccabi Health Fund was, therefore, examined from April to June 1994. Sixty-four per cent of patients received monotherapy and 36% combination therapy. The most commonly prescribed medication for monotherapy were angiotensin-converting enzyme (ACE) inhibitors (33.6%), followed by beta-blockers (28.1%) and calcium channel antagonists (26.6%). Diuretics were prescribed to 7.0% of the patients. Analysis of overall drug utilization showed that diuretics were used in 21.5% of patients, beta-blockers in 39.5%, calcium channel blockers in 46% and ACE inhibitors in 40% of patients. Despite the growing evidence of the benefits of diuretics and beta-blockers, our results show a low utilization of these agents in comparison to other countries. It may be speculated that the lack of national guidelines, the absence of utilization reviews by third party providers as well as differences in patient population and climate conditions may all contribute to the current prescribing habits of physicians in the Israeli community.

Adrenergic beta-Antagonists↗
PubMed1995

Postprandial intestinal-derived chylomicron and chylomicron remnants in essential hypertensive patients before and after prolonged captopril therapy.

The metabolism of the postprandial intestinal-derived lipoproteins, chylomicron and chylomicron remnants, is not known in patients with essential hypertension. After a fat meal, using the vitamin A test as a marker, retinyl palmitate was measured in the total plasma, chylomicron, and chylomicron remnant fractions in 14 untreated nondiabetic essential hypertensive patients with normal fasting lipids and lipoproteins. The vitamin A fat loading test was repeated in eight hypertensive patients after 3 months of captopril therapy. Fifteen matched normotensive subjects were used as controls. The untreated essential hypertensive patients had significantly higher chylomicron fraction concentration curves (AUC 17,469 +/- 2553 micrograms/L/h) P < .001 compared with the control group (AUC 13,208 +/- 1245 micrograms/L/h), by two-way analysis of variance with repeated measurements. After 3 months of captopril therapy, the chylomicron fraction (AUC 9701 +/- 1566 micrograms/L/h), and chylomicron remnants fraction (AUC 3487 +/- 580 micrograms/L/h) were much lower (P < .001) than before captopril therapy. Oral glucose tolerance tests were borderline in five of the eight hypertensives before captopril treatment but returned to normal after 3 months of therapy. In summary, postprandial intestinal-derived lipoprotein metabolism is altered in essential hypertensive patients. Captopril therapy caused significant improvement in the postprandial chylomicron metabolism.

Captopril↗
PubMed1995

Is obstructive sleep apnea a common cause of essential hypertension?

Obstructive sleep apnea (OSA) occurs in about 10% of the middle-aged population but in about 30% of the hypertensive population of the same age. About 20% of the middle-aged population has hypertension but about 50% of patients with OSA have hypertension. Despite this close relationship between these two entities, previous attempts to determine whether the respiratory abnormalities in OSA were responsible for the hypertension were inconclusive, particularly because of the confounding effect of obesity which is common to both conditions. Data from recent observational and intervention studies, however, have succeeded in avoiding many of the pitfalls of earlier studies and it is now becoming evident that OSA may be a major cause of hypertension--responsible for about 30% of all cases. Successful treatment of OSA by any means has been shown in most studies to cause significant reductions in blood pressure throughout the 24 h period, while at the same time alleviating the vast array of symptoms and clinical abnormalities associated with this common and serious condition. Despite the encouraging results of these recent data, more studies are urgently required which should include larger numbers of patients and controls in order to clarify further the relationship between OSA and hypertension.

Airway Obstruction↗
PubMed1994

A cost-benefit analysis of legislation for bicycle safety helmets in Israel.

Legislation requiring bicyclists to wear helmets in Israel will, over a helmet's 5-year duration (assuming 85% compliancy, 83.2% helmet efficiency for morbidity, and 70% helmet efficiency for mortality), save approximately 57 lives and result in approximately 2544 fewer hospitalizations; 13,355 and 26,634 fewer emergency room and ambulatory visits, respectively; and 832 and 115 fewer short-term and long-term rehabilitation cases, respectively. Total benefits ($60.7 million) from reductions in health service use ($44.2 million), work absences ($7.5 million), and mortality ($8.9 million) would exceed program costs ($20.1 million), resulting in a benefit-cost ratio of 3.01:1.

Adolescent↗
PubMed1990

Non-pharmacological treatment of hypertension.

Weight reduction, alcohol restriction, mild salt restriction, eating a vegetarian diet and increasing aerobic exercise will generally lower the blood pressure in patients with essential hypertension. Eating a diet rich in potassium and reducing caffeine intake may also be helpful in reducing the pressure, but increasing the fiber or calcium intake will generally be ineffective. Reducing fat intake from the usual 40% of total calories to 25-30% may reduce hypertension directly or by weight reduction. Smoking, when combined with excessive caffeine or alcohol intake may have an additive effect on blood pressure. Monotherapy with such behavioral techniques as self-monitoring of blood pressure, biofeedback, meditation, yoga, progressive muscular relaxation or cognitive therapy may reduce the blood pressure to a variable degree, and combinations of these treatments may be even more successful.

Behavior Therapy↗
PubMed1990

Comparison of hypertension treatment on and off the worksite.

A survey was carried out in two plants in Haifa, Israel on the prevalence of treated and controlled hypertension. In both plants hypertension treatment was being carried out by family physicians at regular family clinics. In factory A, after screening, a programme of follow-up and treatment by the plant doctor and nurse was introduced. In factory B all hypertensives continued to be referred to their family physician for treatment and follow-up. One year later all previously detected hypertensives were reassessed. The percentage of treated hypertensives had increased from 70.9% to 100% in factory A, and from 55.0% to 62.1% in factory B. The percentage of controlled hypertensives among those treated had increased from 52.7% to 83.7% in factory A, and from 28.0% to 38.9% in factory B. Thus, the percentage of all hypertensives who were controlled increased from 37.3% to 83.7% in Factory A and from 15.4% to 24.1% in Factory B. The introduction of on-site treatment and follow-up of hypertension by a doctor-nurse team was associated with marked improvement of all aspects of hypertensive care.

Family Practice↗
PubMed1990

Group discussions with the health care team--a method of improving care of hypertension in general practice.

A management-by-objective approach was used by the health care administration of the Kupat Holim Sick Fund to improve care of hypertension in 20 family practices in the city of Ashdod in central Israel. The doctor-nurse teams in these clinics met jointly on a regular basis with a physician-instructor, reviewed the results of their care of hypertension and discussed ways of improving it. Over a seven-year period, until 1988, the percentage of the population treated increased from 4.0% to 9.2% and percentage of treated patients who had diastolic pressure of 100 mmHg or more fell from 29.6% to 13.4%. Dropout rate ranged from 2.3% to 3.1% per year over the whole period. In 20 other practices in the Ashdod area in 1988 used for comparison, only 5.9% of the population was treated and the per cent treated was less than Ashdod for all age groups above 30. Dropout rate was higher, averaging 9.8% per year, and the percentage of patients with diastolic pressures of 100 mmHg or more was higher (18.1%). Thus the use of regular discussions with feedback to the health care team was associated with better detection, treatment and follow-up of hypertension.

Adult↗
PubMed1987

Hypertension in European immigrants to Israel--the possible effect of the holocaust.

To examine the effect of stressful life events and chronic emotional distress in the development of hypertension, we compared the blood pressure of 1,150 Israelis (aged 50 to 80) who immigrated from Europe before 1939 with that of 2,159 European-born Israelis who immigrated to Israel after World War II. Most of the subjects were examined as part of a periodical health examination offered by their employers. There were only minor differences in age, height, country of origin and level of education between the two groups. There was no difference in the prevalence of hypertension between the two immigration groups, and a similar percentage of both groups were receiving treatment. Hypertension was defined as any one or more of the following: supine systolic greater than or equal to 160 mm Hg, diastolic greater than or equal to 95 mm Hg, or treatment with antihypertensive medications. Analysis of variance showed that age, sex and degree of obesity were the main factors contributing to the blood pressure. Although the degree of emotional stress was greater in the Holocaust survivors, there was no correlation between level of emotional distress, satisfaction with life or number of psychosomatic complaints and level of blood pressure or prevalence of hypertension.

Aged↗