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Biomedical subjects

I Karacan

Publications and source records attributed to I Karacan.

At least 19 recordsLinked to original sources
PubMed1992

Nocturnal penile tumescence in cigarette smokers with erectile dysfunction.

We examined the relationship between cigarette smoking and erectile physiology in 314 men with erectile dysfunction. All of the men studied were currently cigarette smokers. Evaluations included interviews, physical examinations, and polysomnographic assessment of sleep-related erections. Penile rigidity during nocturnal erection inversely correlated with the number of cigarettes smoked per day. Smoking was also associated with indices of impairment on autonomic function tests and some measures of penile blood pressure. The group of men who smoked the most (more than 40 cigarettes per day) had the fewest minutes of nocturnal tumescence and detumesced fastest. These data are discussed with respect to the results of studies performed in dogs that demonstrated smoking-related reduction in arterial flow and venous restriction. Our findings suggest that smoking may further compromise penile physiology in men experiencing difficulty in maintaining erections long enough for satisfactory intercourse.

Adult↗
PubMed1992

Polysomnography of adults and elderly: sleep architecture, respiration, and leg movement.

Polysomnographic data recorded from a large sample of normal, healthy, adult volunteer subjects are reported. First and second night summary values are included. Results agree remarkably well with previously published findings and the age-related differences in sleep architecture that we found are described in detail. We also discuss some of the unique methodological problems associated with developing normative sleep values.

Adult↗
PubMed1990

Prevalence of sleep apnea in men with erectile dysfunction.

Sleep studies were performed on 1,025 patients complaining of erectile dysfunction. In addition to standard measures of sleep stage and nocturnal penile tumescence, respiratory activity was evaluated. The number of episodes of sleep apnea per hour (Apnea Index--AI) was calculated for each patient. The overall prevalence of sleep apnea activity in this sample was: 43.8 percent with AI greater than or equal to 5; 27.9 percent with AI greater than or equal to 10; and 19.6 percent with AI greater than or equal to 15. These results confirm that sleep apnea activity is common in men with erectile dysfunction. This high prevalence also indicates that further study is needed to elucidate pathophysiology of erectile failure in men with sleep apnea.

Adult↗
PubMed1990

Comparison of penile duplex ultrasonography with nocturnal penile tumescence monitoring for the evaluation of erectile impotence.

A total of 50 patients with erectile dysfunction underwent comprehensive evaluation, including vascular evaluation with penile duplex ultrasonography and papaverine injection, as well as nocturnal penile tumescence monitoring. The latter was performed in a sleep laboratory setting in all patients. The results of penile duplex ultrasonography with papaverine injection were classified as 18 patients with normal vascular findings, 22 with arterial insufficiency, 3 with the pelvic steal syndrome and 7 with isolated venous leakage. Of the patients 15 had normal ultrasonographic and nocturnal penile tumescence findings, 29 had abnormal ultrasonographic vascular and nocturnal penile tumescence findings, 3 had abnormal ultrasonographic vascular findings and normal nocturnal penile tumescence (including 1 with the pelvic steal syndrome as evidenced by penile brachial index) and 3 had normal ultrasonographic vascular findings and abnormal nocturnal penile tumescence (including 2 with neurogenic erectile dysfunction). Penile duplex ultrasonography with papaverine injection appears to be a useful objective method to evaluate vasculogenic impotence and to correlate favorably with nocturnal penile tumescence monitoring. It also may have a higher yield than nocturnal penile tumescence monitoring in patients with the pelvic steal syndrome. While nocturnal penile tumescence is impaired in patients with neurogenic impotence, penile duplex ultrasonography with papaverine injection reveals, as expected, normal findings in patients with neurogenic impotence and normal vascular systems.

Adult↗
PubMed1990

Diabetes, erectile dysfunction, and sleep-related erections.

Sleep-related erections were assessed in conjunction with polysomnography in 100 diabetic and 400 nondiabetic men with complaints of erectile problems. We also measured bulbocavernosus reflex latency, heart rate response to deep breathing, postural-related blood pressure changes, penile arterial sufficiency, and brachial blood pressures. To investigate the relationship between diabetes and erectile capacity, the results obtained from men with and without diabetes were compared. Men with diabetes had fewer sleep-related erections, less tumescence time, diminished penile circumference increase, and lower penile rigidity than nondiabetic men. These diabetes-related differences were found regardless of the maximum penile rigidity observed. The diabetic group had less heart rate response to deep breathing and lower penile blood pressures than the nondiabetic group, but only among men with maximum penile rigidity less than 500 g. These data indicate that both neurological and vascular mechanisms are involved to a greater degree in organic diabetic impotence than in the organic erectile dysfunction that occurs in nondiabetic men. Finally, the pattern of lower values for measures of nocturnal tumescence among diabetic men, compared to nondiabetic men, occurred in all age groups, except the oldest. Among impotent men, age 65 years or older, no difference was found between men with and without diabetes. This suggests that diabetes may foreshadow some of the age-related pathophysiological processes associated with erectile dysfunction.

Adult↗
PubMed1990

Testosterone replacement therapy and sleep-related erections in hypogonadal men.

Hypogonadal men usually have diminished libido and erectile dysfunction, and testosterone replacement therapy in these men increases sexual activity, erotic thoughts, and self-reported nocturnal erections. The polygraphic assessment of nocturnal penile tumescence (NPT) provides an objective index of erectile capability and is useful for differentiating psychogenic from organic erectile dysfunction. In this study we evaluated NPT in six hypogonadal adult men during and after termination of androgen therapy. Multinight sleep studies were conducted within 1 week and 7-8 weeks after each man received 20 mg testosterone cypionate, im. The mean serum testosterone level 4-7 days after testosterone injection was 35.9 +/- 3.4 (+/- SE) nmol/L, and it fell to 2.3 +/- 0.9 nmol/L after 7-8 weeks. Significant declines (P less than 0.05) in the number of NPT episodes (3.7 to 2.0), maximum penile circumference increase (24 to 13 mm), and total tumescence time (107 to 55 min) accompanied the fall in the serum testosterone level. No androgen-related changes in the amount or integrity of rapid eye movement sleep were found. Finally, the mean penile rigidity (buckling pressure) decreased from 770 +/- 98 to 590 +/- 81 g (P less than 0.05). Comparison of these results to those in normal men revealed that none of these men met all diagnostic criteria for organic impotence, even 7-8 weeks after discontinuation of testosterone administration. While men with androgen deficiency may have normal NPT, sleep-related erections increase in response to testosterone administration.

Adult↗
PubMed1989

Erectile dysfunction in hypertensive men: sleep-related erections, penile blood flow and musculovascular events.

To explore how hypertension affects penile erection, we studied erectile hemodynamics during nocturnal penile tumescence in 3 groups of middle-aged men: hypertensive patients with and without erectile dysfunction, and normotensive controls without erectile problems. The hypertensive patients were not taking antihypertensive medication. Evaluations included standard monitoring of penile circumference change as well as noninvasive monitoring of penile segmental pulsatile blood flow and activity in the bulbocavernosus-ischiocavernosus muscles. Variables differed in how they discriminated among groups. Median amplitude of penile blood flow during rapid eye movement sleep differed significantly among all 3 study groups: controls had the highest amplitudes, patients without erectile problems had lower values and patients with erectile complaints had the lowest values. By contrast, standard measures of nocturnal penile tumescence (that is based on penile circumference change during sleep) only distinguished the patients with erectile problems from the 2 other groups. Density of musculovascular event clusters during rapid eye movement sleep (nearly simultaneous muscle activity burst, blood flow burst and circumference pulsation) distinguished the 2 groups of hypertensive men from controls. The sensitivity of the blood flow measure to changes in the hypertensive men without erectile complaints may indicate that the measure can reveal subclinical signs of developing vasculogenic erectile dysfunction.

Hemodynamics↗
PubMed1989

Hypertension, erectile dysfunction, and occult sleep apnea.

Sleep-related respiratory pattern was evaluated in 175 hypertensive and 110 normotensive men, none of whom reported difficulties in initiating or maintaining sleep. Patients were grouped according to sexual status (complaint of erectile problems), hypertension treatment status (treated or untreated), and blood pressure (diastolic less than 90 or greater than or equal to 90). The prevalence of sleep apnea, apnea index, duration of the longest episode of apnea, and penile rigidity were tabulated. The group with elevated blood pressure, persistent even with antihypertensive drug therapy, had the most sleep apnea. The treated hypertensive men with controlled blood pressure had significantly less apnea than those whose blood pressure remained high. Untreated hypertensive groups, however, did not differ from normotensive groups with respect to apnea. Evidence of abnormal sleep-related respiratory activity was found in both hypertensive and normotensive groups with erectile problems. Interestingly, penile rigidity was significantly lower for hypertensive men with erectile complaints than for normotensive men with erectile complaints. There was also a small, but significant, negative correlation between apnea index and penile rigidity among men with erectile complaints. These results indicate that sexual status is an important consideration in the diagnosis of hypertension and sleep apnea. Moreover, these data suggest an interrelationship among hypertension, erectile dysfunction, and sleep apnea.

Antihypertensive Agents↗
PubMed1986

Cerebral responses evoked by stimulation of the vesico-urethral junction in normal subjects.

Following bipolar stimulation of the vesico-urethral junction (VUJ), evoked potentials (EPs) with a late and prominent negativity (mean latency 91.4 +/- 11.0 msec) were recorded from scalp in 22 male subjects. Although remarkable intersubject variations occurred, no peak variation could be seen in any given subject. Maximum amplitude of the EPs was recorded from Cz and CzP points. Stimuli with various frequencies did not lead to any differences in shape and latency of EPs. The differences between the EPs by bipolar stimulation of the VUJ and the responses elicited by distal urethral and pudendal nerve stimulation suggest that, during bipolar stimulation of VUJ, the somatic afferents were not excited. Therefore, these responses were most likely due to the excitement of the visceral afferents arising from the VUJ separately. This method may be a useful technique for evaluating the physiological condition of the afferent nerves arising from VUJ.

Adult↗
PubMed1986

Cerebral responses evoked by stimulation of vesico-urethral junction in man: methodological evaluation of monopolar stimulation.

Cerebral responses after bipolar stimulation (BpS) and monopolar stimulation (MpS) of the vesico-urethral junction (VUJ), as well as skin surface stimulation of various hip and pelvic structures, were recorded in 13 normal control subjects. BpS of VUJ produced cerebral evoked potentials (CEPs) with a negative peak (mean latency 88.69 +/- 13.73 msec) following a smaller positive deflection, while MpS of the same sites with indifferent electrodes placed on various pelvic or hip structures resulted in different response latencies that were all significantly shorter than those of BpS. Shape and latency of responses after MpS of VUJ were similar to those elicited by skin surface stimulation of the abdominal wall and the iliac crest; those elicited by pudendal nerve stimulation at the glans were also similar in shape but significantly greater in latency. Results strongly indicate that during MpS of VUJ the somatic or muscle afferents located in the hip and pelvic region are stimulated; consequently, BpS technique should be considered the preferred technique for investigating the physiological condition of visceral afferents arising from VUJ.

Adult↗
PubMed1979

Erectile impotence treated with an implantable, inflatable prosthesis. Five years of clinical experience.

Erectile impotence can now be treated with a device that mimics a natural erection. Between 1973 and 1977, we implanted an inflatable prosthesis in 245 men (235 with organic impotence and ten with psychogenic impotence). Of these, 234 are able to use the device to their satisfaction; no failures have occurred in the 152 cases treated in 1976 and 1977. The success of this treatment rests in part on the careful selection of patients by a team--a urologist, a sleep researcher, a psychologist, and a psychiatrist--each evaluating the patient independently. Our experience suggest that erectile impotence may be more common than generally believed and that impotence from organic causes may account for a greater percentage of cases than formerly thought.

Adult↗
PubMed1979

Narcolepsy: regional cerebral blood flow during sleep and wakefulness.

Serial measurements of regional cerebral blood flow were made by the 135Xe inhalation method during the early stages of sleep and wakefulness in eight normal volunteers and 12 patients with narcolepsy. Electroencephalogram, electro-oculogram, and submental electromyogram were recorded simultaneously. In normals, mean hemispheric gray matter blood flow (Fg) during stages I and II sleep was significantly less (-9.2 percent) than waking values (84.3 +/- 13 ml per 100 gm brain per minute). Maximum regional blood flow decreases during sleep occurred in the brainstem-cerebellar (-25.1 percent), right inferior temporal (-23.1 percent) and bilateral frontal (-18.9 percent) regions (p less than 0.05). In patients with narcolepsy, mean hemispheric Fg while awake was 80.5 +/- 13 ml per 100 gm brain per minute. During REM sleep (n = 2), mean hemispheric Fg increased by 9.8 percent concurrently with large increases (+34.6 percent) in brainstem-cerebellar region flow. During stages I and II sleep without REM (n = 6), there were significant increases in mean hemispheric Fg of +/-20.2 percent (p less than 0.01) and brainstem-cerebellar Fg of 38.0 percent (p less than 0.01), just the opposite of changes in normals. In narcolepsy, there appears to be a reversal of normal cerebral deactivation patterns, particularly involving the brainstem, during stages I and II sleep.

Adult↗
PubMed1979

Automated measurement of alpha, beta, sigma, and theta burst characteristics.

An automatic system was used for the selection and analysis of alpha, beta, and theta waveforms occurring in the awake and REM sleep states and sleep spindles occurring in stage 2 sleep. Two nights of sleep were analyzed for each of five normal subjects in each of five age groups: 3--5; 13; 25--34; 43--53; and 67--79 years of age. The waveform frequencies, length, and rate of occurrence were measured. No age-related changes were found in the alpha frequency (except for the younger group). No significant age differences were found in the beta and theta frequencies in the awake state. During REM sleep, the average beta and theta frequencies of the two youngest groups were significantly different from those of the three older groups. The average frequency of stage 2 sleep spindles of the two youngest groups was less than that in the middle group; the average spindle frequency of this group was significantly less than that of the two older groups. The number of spindles per minute was significantly less for the younger group and significantly more for the 25- to 34-year-olds.

Adolescent↗
PubMed1978

Impotence and blood pressure in the flaccid penis: relationship to nocturnal penile tumescence.

Evaluations of nocturnal penile tumescence (NPT) and penile blood pressure were performed on (1) a group of nondiabetics with normal NPT, (2) a group of nondiabetics with abnormally diminished NPT, and (3) a group of diabetics with abnormally diminished NPT. The 12 subjects in each group complained of impotence. Analysis of blood pressure data taken before the NPT evaluation suggests the possibility of selective low arterial blood pressure in impotent patients who show no obvious signs of other vascular disorders.

Blood Pressure↗
PubMed1978

Nocturnal penile tumescence and diagnosis in diabetic impotence.

The authors conducted a study of nocturnal penile tumescence (NPT) in 35 diabetic men, aged 33 to 70, who complained of impotence and in 35 age-matched control subjects. EEGs and other measurements showed that the diabetic men as a group exhibited significant reductions in the total amount of NPT and in the amount and frequency of full erection, thus suggesting that impotence in this cohort was organogenic. Although NPT monitoring represents an advance over the less precise traditional procedures for the differential diagnosis of impotence, the authors stress the need for more research in this area.

Adult↗