Response of Lipids and Lipoproteins to Regular Aquatic Endurance Exercise: A Meta-Analysis of Randomized Controlled Trials

Aim: No meta-analysis has examined the effect of regular aquatic endurance exercise on lipid and lipoprotein levels. The purpose of the current work was to perform a meta-analysis to evaluate the effects of regular aquatic endurance exercise on lipid and lipoprotein levels.

Methods: The inclusion criteria of the randomized controlled trials were healthy adults in an exercise group performing regular aquatic exercise and a control group not exercising, with a description of the serum high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol, or triglyceride levels provided. The net change in the lipid and lipoprotein levels was calculated from each trial, and the changes in the lipid and lipoprotein levels were pooled using a random effects model.

Results: The meta-analysis examined 10 trials involving aquatic endurance exercise and 327 subjects. The pooled net changes in HDL-C, LDL-C, and total cholesterol improved significantly (HDL-C, 4.6 mg/dL; LDL-C, −10.1 mg/dL; total cholesterol, −8.5 mg/dL). When trials were limited to those involving only women, the pooled net changes in HDL-C, LDL-C, and total cholesterol improved significantly. When trials were limited to those involving subjects with a mean age < 60 years, the pooled net changes in HDL-C, total cholesterol, and triglyceride improved significantly. When trials were limited to those with dyslipidemia, the pooled net changes in HDL-C, LDL-C, total cholesterol, and triglyceride improved significantly.

Conclusions: Aquatic endurance exercise improved the lipid and lipoprotein levels and benefited women, middle-aged subjects, and patients with dyslipidemia in particular.

Wave intensity as a useful modality for assessing ventilation-perfusion imbalance in subclinical patients with hypertension

Wave intensity (WI) is a novel noninvasive index of circulatory dynamics that reflects ventriculo-arterial coupling. It is calculated as the product of the first derivative of blood pressure and that of flow velocity measured by carotid echocardiography. This study aimed to clarify the clinical implications of WI and its relation with carbon dioxide production (VE/VCO₂ slope). Twenty-one healthy volunteers (control group) and 21 patients with hypertension (HT group) underwent cardiopulmonary exercise testing (CPX) and exercise stress echocardiography. WI was assessed in the right carotid artery using an ultrasound system. The first peak of WI (W₁) during the early ejection phase was measured at baseline and mitral annular velocity was assessed by tissue Doppler imaging. Ventilatory kinetics during exercise was assessed using the relation of minute ventilation to VE/VCO₂ slope. VE/VCO₂ slope, W₁, and E/E' were greater in the HT group than in the control group. PeakVO₂ and VO₂ at the anaerobic threshold were lower in the HT group than in the control group. VE/VCO₂ slope was significantly correlated with W₁ (r = 0.58, p < 0.01) and E/E' (r = 0.44, p < 0.01). Stepwise multivariate analysis revealed that W₁ was an independent determinant of VE/VCO₂ slope (β = 0.43, p < 0.01). In conclusion, W₁ might be able to predict the severity of heart failure without the need for CPX. Moreover, WI may be a useful modality in assessing heart failure pathophysiology based on ventriculo-arterial coupling.

The effect of regular aquatic exercise on blood pressure: A meta-analysis of randomized controlled trials

Background

No meta-analysis has examined the effect of regular aquatic exercise on blood pressure. The purpose of this study was to perform a meta-analysis to evaluate the effects of regular aquatic exercise on blood pressure.

Design

A meta-analysis of randomized controlled trials.

Methods

Databases were searched for literature published up to April 2017. The randomized controlled trials analysed involved healthy adults, an intervention group that only performed aquatic exercise and a control group that did not exercise, no other intervention, and trials indicated mean systolic blood pressure or diastolic blood pressure. The net change in blood pressure was calculated from each trial, and the changes in blood pressure were pooled by a random effects model, and the risk of heterogeneity was evaluated. Subgroup analysis of subjects with hypertension, subjects who performed endurance exercise (or not), and subjects who only swam (or not) was performed, and the net changes in blood pressure were pooled.

Results

The meta-analysis examined 14 trials involving 452 subjects. Pooled net changes in blood pressure improved significantly (systolic blood pressure −8.4 mmHg; diastolic blood pressure −3.3 mmHg) and the changes in systolic blood pressure contained significant heterogeneity. When subjects were limited to those with hypertension, those who performed endurance exercise and subjects who did not swim, pooled net changes in systolic and diastolic blood pressure decreased significantly, but the heterogeneity of systolic blood pressure did not improve.

Conclusion

Like exercise on land, aquatic exercise should have a beneficial effect by lowering blood pressure. In addition, aquatic exercise should lower the blood pressure of subjects with hypertension, and other forms of aquatic exercise besides swimming should also lower blood pressure.

The influence of central arterial compliance on cerebrovascular hemodynamics: insights from endurance training intervention

Normally, central elastic arteries (e.g., aorta and common carotid artery) effectively buffer cardiac pulsation-induced flow/pressure fluctuations. With advancing age, arterial stiffening deteriorates this function and produces the greater cerebral hemodynamic pulsatility that impacts vulnerable brain tissue. It is well known that the buffering function of the central artery is improved by regular aerobic exercise, but the influence of endurance training on the pulsatile component of cerebral hemodynamics remains poorly understood. To characterize the functional role of the central artery at the heart-brain hemodynamic connection comprehensively, we assessed relations among the endurance training-induced changes in the left ventricle (LV), carotid arterial compliance, and cerebral hemodynamics. Thirteen collegiate tennis players (20 ± 1 yr) underwent a 16-wk endurance training intervention designed for improving cardiovascular function. Expectedly, maximal oxygen uptake (V̇o2peak), LV ejection velocity (via Doppler ultrasound), and the maximal rate of pressure increase of estimated aortic pressure waveform (via general transfer function) improved after the training intervention, whereas middle cerebral arterial (MCA) hemodynamics (via transcranial Doppler), such as mean and pulsatile flow velocities, remained unchanged. Carotid arterial compliance (via ultrasound and applanation tonometry) increased after the training intervention, and a larger increase in carotid arterial compliance was significantly associated with the greater attenuations of pulsatile MCA velocity ( r = −0.621) normalized by mean MCA velocity. These results suggest that the training-induced improvement of carotid artery Windkessel function might offset the expected increase in the pulsatile component of cerebral perfusion induced by the enhanced LV systolic function.

Abnormal early diastolic intraventricular flow 'kinetic energy index' assessed by vector flow mapping in patients with elevated filling pressure

AIMS

Recently developed vector flow mapping (VFM) enables evaluation of local flow dynamics without angle dependency. This study used VFM to evaluate quantitatively the index of intraventricular haemodynamic kinetic energy in patients with left ventricular (LV) diastolic dysfunction and to compare those with normal subjects.

METHODS AND RESULTS

We studied 25 patients with estimated high left atrial (LA) pressure (pseudonormal: PN group) and 36 normal subjects (control group). Left ventricle was divided into basal, mid, and apical segments. Intraventricular haemodynamic energy was evaluated in the dimension of speed, and it was defined as the kinetic energy index. We calculated this index and created time-energy index curves. The time interval from electrocardiogram (ECG) R wave to peak index was measured, and time differences of the peak index between basal and other segments were defined as ΔT-mid and ΔT-apex. In both groups, early diastolic peak kinetic energy index in mid and apical segments was significantly lower than that in the basal segment. Time to peak index did not differ in apex, mid, and basal segments in the control group but was significantly longer in the apex than that in the basal segment in the PN group. ΔT-mid and ΔT-apex were significantly larger in the PN group than the control group. Multiple regression analysis showed sphericity index, E/E' to be significant independent variables determining ΔT apex.

CONCLUSION

Retarded apical kinetic energy fluid dynamics were detected using VFM and were closely associated with LV spherical remodelling in patients with high LA pressure.

Experimental evaluation of photocrosslinkable chitosan hydrogel as injection solution for endoscopic resection

BACKGROUND AND STUDY AIMS

Saline as an injection solution for endoscopic resection techniques has several disadvantages such as a short-lasting effect leading to a potentially higher risk of bleeding and perforation. The new substance of photocrosslinkable chitosan hydrogel in a DMEM/F12 medium (PCH) can be converted into an insoluble hydrogel by ultraviolet irradiation for 30 s, and was evaluated in two sets of animal experiments.

METHODS

18 pigs were used in the two parts of the study. First, mucosal resections were done with either PCH or hypertonic saline; the effects of both agents on wound healing were examined endoscopically and histologically. Second, in vivo degradation of PCH was examined using six pig stomachs.

RESULT

PCH injection led to a longer-lasting elevation with clearer margins, compared with hypertonic saline, thus enabling precise endoscopic submucosal dissection (ESD) along the margins of the elevated mucosa. The endoscopic appearance after ESD was similar in both groups. PCH biodegradation was completed within 8 weeks according to endoscopic and histologic analyses.

CONCLUSION

PCH is a promising agent for submucosal injection prior to various techniques of endoresection. It should be evaluated in clinical trials after biocompatibility testing for PCH is completed.

Postmarketing surveillance of the safety profile of infliximab in 5000 Japanese patients with rheumatoid arthritis

OBJECTIVES

A large-scale postmarketing surveillance (PMS) study was carried out to determine the safety profile of infliximab in Japanese patients with rheumatoid arthritis (RA).

METHODS

The PMS study was performed for all patients with RA who were treated with infliximab. They were consecutively registered in the PMS study at the initiation of infliximab treatment and were prospectively monitored with all adverse events noted for a period of 6 months. All case reports, which include safety-related events, were collected monthly.

RESULTS

Adverse drug reactions (ADRs) were assessed for 6 months in 5000 patients who were consecutively enrolled in the PMS study. The incidence rates of total and serious ADRs were 28.0% and 6.2%, respectively. "Infections" or "respiratory disorders" were most commonly observed among serious ADRs. Bacterial pneumonia developed in 2.2%, tuberculosis in 0.3%, suspected Pneumocystis jiroveci pneumonia (PCP) in 0.4% and interstitial pneumonitis in 0.5%. Bacterial pneumonia (for which individuals of male gender, of older age and those with advanced rheumatoid arthritis and comorbid respiratory disease were most at risk) began to develop immediately after the start of treatment, while tuberculosis, PCP and interstitial pneumonitis developed about 1 month later. Serious infusion reactions were observed in 0.5% and were more likely to occur in patients who had participated in previous clinical trials of infliximab.

CONCLUSION

This postmarketing surveillance study of patients treated with infliximab showed that infliximab in combination with low-dose MTX was well tolerated in Japanese patients with active RA.

Submucosal injection, for endoscopic mucosal resection, of photocrosslinkable chitosan hydrogel in DMEM/F12 medium

BACKGROUND AND STUDY AIMS

We studied the ability of a photocrosslinkable chitosan in DMEM/F12 medium to maintain submucosal thickness and to reduce bleeding after mucosal resection. We also investigated the behavior of chitosan hydrogels with regard to wound healing.

METHODS

The gastric submucosal layer of heparinized rats was injected with the photocrosslinkable chitosan in medium (which was then irradiated with ultraviolet light to form a hydrogel), or with sodium hyaluronate, or hypertonic saline, and three investigations were done, using three different sets of rats. The first and second were measurement of the thickness of the layer, and of the amount of bleeding induced by mucosal resection, respectively. Thirdly, the effects of the chitosan hydrogel on wound healing were examined histologically.

RESULTS

Gastric submucosal layers of chitosan hydrogel-treated animals remained significantly thicker than those of other groups for at least 6 h after injection. The total amount of bleeding 20 min after mechanical mucosal resection was 170.0 +/- 20.0 mg, 678.3 +/- 226.3 mg, and 1020.0 +/- 104.1 mg in the chitosan hydrogel, sodium hyaluronate, and hypertonic saline groups, respectively. Histological study revealed that the focus of bleeding was surrounded by chitosan hydrogel and that almost all the hydrogel was biodegraded within 4 weeks. Furthermore, a discernible, but not statistically significant effect of the chitosan hydrogel on wound healing was observed.

CONCLUSIONS

The chitosan hydrogel produced mucosal elevation after submucosal injection with ultraviolet irradiation, and it significantly reduced bleeding after mucosal resection. Our newly developed chitosan hydrogel in medium might be a promising submucosal agent for endoscopic mucosal resection.

Effect of antiarrhythmic agents on heart rate variability indices after myocardial infarction: comparative experimental study of aprindine and procainamide

The cardiac arrhythmic suppression trial (CAST) reported that antiarrhythmic treatments in post-myocardial infarction (MI) patients resulted in poor outcome and decreased in heart rate variability indices (HRV). The goal of the present study was to determine whether aprindine and procainamide, antiarrhythmic agents that increase HRV, result in beneficial effects in post-MI rabbits. Four weeks before experiment, MI was induced in four rabbits by ligating the major branch of left coronary artery. A total of eight rabbits (four post-MI and four normal rabbits) were randomly assigned to treatment with either intravenous aprindine (1 mg/kg) or intravenous procainamide (15 mg/kg). Frequency domain HRV (low frequency spectra, LF, 0.04-0.15 Hz; high frequency spectra, HF, 0.15-0.40 Hz) were assessed by MemCalc software. Aprindine significantly increased HF and LF in both MI and normal rabbits, whereas procainamide tended to decrease HF and LF in MI and normal rabbits (in total rabbits; aprindine, LF, from 6.3 +/- 7.9 to 16.5 +/- 15.0 ms(2)/Hz, P < 0.05; HF, from 8.0 +/- 11.7 to 17.5 +/- 15.0 ms(2)/Hz, P < 0.05; procainamide, LF, from 4.9 +/- 7.4 to 4.8 +/- 8.5 ms(2)/Hz, NS; HF, from 11.1 +/- 23.0 to 5.1 +/- 10.6 ms(2)/Hz, NS). Under pharmacological denervation with propranolol (0.1 mg/kg) and atropine (0.04 mg/kg), aprindine increased LF and HF (LF, from 0.2 +/- 0.2 to 0.8 +/- 0.7 ms(2)/Hz, P < 0.05; HF, from 0.1 +/- 0.0 to 0.2 +/- 0.0 ms(2)/Hz, P < 0.05). These data suggest that aprindine can increase HRV in post-MI rabbits. Further experiments in human subjects would be of benefit.

An organic thyristor

Thyristors are a class of nonlinear electronic device that exhibit bistable resistance--that is, they can be switched between two different conductance states. Thyristors are widely used as inverters (direct to alternating current converters) and for the smooth control of power in a variety of applications such as motors and refrigerators. Materials and structures that exhibit nonlinear resistance of this sort are not only useful for practical applications: they also provide systems for exploring fundamental aspects of solid-state and statistical physics. Here we report the discovery of a giant nonlinear resistance effect in the conducting organic salt theta-(BEDT-TTF)2CsCo(SCN)4, the voltage-current characteristics of which are essentially the same as those of a conventional thyristor. This intrinsic organic thyristor works as an inverter, generating an alternating current when a static direct-current voltage is applied. Whereas conventional thyristors consist of a series of diodes (their nonlinearity comes from interface effects at the p-n junctions), the present salt exhibits giant nonlinear resistance as a bulk phenomenon. We attribute the origin of this effect to the current-induced melting of insulating charge-order domains, an intrinsically non-equilibrium phenomenon in the sense that ordered domains are melted by a steady flow.

Structure and lipophilicity profile of 2,3-anhydro-alpha-cyclomannin and its ethanol inclusion complex

Readily available from alpha-cyclodextrin in three steps, 2,3-anhydro-alpha-cyclomannin composed of six alpha-(1-->4)-linked 2,3-anhydro-D-mannopyranose residues, crystallizes well when precipitated from aqueous ethanol. An X-ray structure reveals the macrocycle to contain ethanol in its cavity, thus representing the first inclusion complex of a non-glucose cyclooligosaccharide. The wider rim of the torus-shaped macrocycle holds the six epoxide rings whose oxygens point away from the cavity, thereby sculpturing the unique over-all shape of a six-pointed star.

The dependence of catalytic activities of secondary functional beta-cyclodextrins on cavity structures

Secondary imidazole-appended beta-cyclodextrin 5 with a nondistorted cavity synthesized from a novel intermediate 3-amino-3-deoxy-beta-cyclodextrin exhibits much greater catalytic activity in the ester hydrolysis than its isomer 6 with a distorted cavity, indicating that the catalytic activities of secondary functional cyclodextrins are dependent on cavity structures.

Eating disorders in Japan: a review of the literature

Although a form of eating disorders had been described by Kampo (Chinese traditional medicine) physicians during the last quarter of the 18th century, the modern study on eating disorders in Japan dates from the end of the 1950s. With the rapid increase in the number of cases, research activities have become very active recently. Both the past and present status of eating disorders and of research activities relating to them in Japan are not well known in other countries. This study concentrates on a review of the literature, with a focus on prevalence, etiology, and symptoms.

Size-selective sampling of oil mist in air and subjective symptoms among machine workers

Oil mists at an automobile factory were measured size-selectively. Furthermore, subjective symptoms were surveyed through the distribution of a questionnaire. The measured levels of respirable-size, 2-10 micrometer oil mists at 3 selected workshops ranged 0.04-0.09 mg/m3 for the lower exposed group (17 men), 0.10-0.18 mg/m3 for the higher exposed group (16 men) to water-insoluble oil, and 0.08-0.29 mg/m3 for the higher exposed group (19 men) to water-soluble oil. The higher the level of exposure to respirable-size particulates, the more workers complained of dissatisfaction with air quality. As to the subjective symptoms, the "yes" rate for "irritated nose" and "sneezing" showed significant differences among the unexposed, lower exposed, and higher exposed groups. Workers using water-soluble oil complained of "uncomfortable smell" more than those who used water-insoluble oil. The results of this study suggested that it is necessary to measure the levels of oil mists size-selectively.

[Left ventricular pseudoaneurysm at the apex--a case report of successful resection of the enlarging pseudoaneurysm following mitral valve replacement, which was caused by closed mitral commissurotomy 23 years ago]

A 47-year-old male with pseudoaneurysm of the left ventricle secondary to mitral valve replacement was herein reported because of its unique etiology. The pseudoaneurysm was presumably resulted from the mitral valve dilator wound at the apex of the left ventricle, which was produced by closed mitral commissurotomy 23 years ago. To our knowledge, it seems to be a rare reported case with pseudoaneurysm of the left ventricle caused by closed transventricular mitral commissurotomy.

Treatment of a giant coronary artery aneurysm in an adult with a history of Kawasaki disease by resection and bypass grafting: report of a case

We report herein the case of a 22-year-old man with a history of Kawasaki disease who developed a giant calcified aneurysm of the left main coronary artery. The aneurysm was successfully resected and coronary bypass surgery was performed using the bilateral internal thoracic arteries. The resected aneurysm, the maximal diameter of which was 27 mm, showed heavy calcification of the inner layer and extended into the adjacent coronary arteries, producing a significant narrowing of the lumen of both the left main trunk (50%) and the anterior descending branch (50%). Extensive intimal calcification presumably prevented normal luminal development and produced a significant narrowing as the patient grew into adulthood. A cause for stenotic lesions developing in the coronary artery adjacent to a coronary aneurysm in adults with a history of Kawasaki disease is suggested here by the resected aneurysm seen in this patient. Thus, adult patients with giant coronary artery aneurysms and significant stenotic lesions of the coronary artery associated with Kawasaki disease may require aneurysmectomy in addition to bypass surgery.

[Exertional hypoxemia evaluated by pulse oximetry in patients with interstitial lung diseases]

The pattern of change in arterial oxyhemoglobin saturation (SpO2) measured by pulse oximetry (PO) during exercise, including daily activities, was studied in 23 patients with interstitial lung disease (ILD), 19 of whom had idiopathic pulmonary fibrosis, 3 collagen vascular disease, and 1 BOOP. Hypoxemia, as detected by PO appeared without dyspnea at the beginning of exertion or at a mild workload. Exercise usually induced significant changes in the same fashion first in heart rate, then in SpO2, and then in dyspnea, but stair climbing had a different pattern. Workload at the lactate threshold (LT) and symptom-limited maximal exercise (SL) in a bicyclergometer incremental exercise test correlated well with distance walked in a 10-minute walking test (10-eMD) (p < 0.01). Similarly, the degree in desaturation in each exercise test was closely correlated (p < 0.01). Exertional hypoxemia was more prominent in patients with ILD than in those with chronic pulmonary emphysema. Nevertheless, dyspne changed less per change in SpO2 in ILD patients. We conclude that prolonged monitoring of SpO2 by PO will disclose the presence of exertional desaturation in ILD patients.

Evaluation of urinary enzymes in dogs with early renal disorder

We investigated urinary N-acetyl-beta-D-glucosaminidase NAG (EC 3.2.1.30), gamma-glutamyl transpeptidase gamma-GTP (EC 2.3.2.2) and glycyl-prolyl dipeptidyl aminopeptidase GP-DAP (EC 3.4.14.5) in dogs with heartworm disease and renal failure. In the renal failure dogs, the NAG, gamma-GTP and GP-DAP index were significantly higher than those in the healthy dogs. In the heartworm disease dogs with normal chest X-rays (HW I), none of the enzyme values was significantly different from those of the healthy controls. In the dogs with heartworm disease showing abnormal heart shadows on their chest X-rays (HW II), enzyme values were significantly higher than those in the healthy dogs (P < 0.01) and the HW I dogs (P < 0.01). Thus, these urinary enzymes tests are available for the early detection of renal disorders.

Pathological changes in epidemic porcine Pneumocystis carinii pneumonia

An outbreak of epidemic porcine Pneumocystis carinii pneumonia on a "farrow-to-finish" pig farm was examined. The clinical disease was observed in weanling piglets, mostly in the seventh to eleventh weeks of life. Lesions of P. carinii pneumonia were detected histologically in the pigs at 36 to 75 days of age. These included pulmonary septal thickening, with mononuclear cell infiltration, swelling of the alveolar lining, an intra-alveolar exudate and the presence of P. carinii organisms. Focal pneumonia was seen at 36-43 days of age and diffuse pneumonia at 46-75 days. This outbreak resembled the infantile epidemic form of P. carinii pneumonia in man, in being age-related and in causing a non-suppurative intense inflammatory response in the lungs.

Chronological changes of MRI findings on striatal damage after acute cyanide intoxication: pathogenesis of the damage and its selectivity, and prevention for neurological sequelae: a case report

A 31-year-old male technician in an electroplating factory, who had been suffering from the temporal lobe epilepsy for 24 years and from hypertension for 2 years, took an unknown amount of potassium cyanide apparently over the lethal dose, in an attempt to commit suicide. He was treated successfully and survived without any neurological sequelae. The electroencephalograms and the nature of the seizures were not different before and after the poisoning. The T2-weighted magnetic resonance images at 9 and 51 days after the poisoning showed bilateral elevation of signals in the caudate nuclei and the putamina. At the 143th and 286th days. T2-weighted high-resonance areas were restricted to the lateral portion of the putamina. The T1-weighted images at the 51st day showed abnormal signal elevations in both putamina, while those of 9th, 143th and 286th days were mainly normal. Selective vulnerability of the putamen and the caudate nucleus may be due to their specific structural properties of high oxygen and glucose utilization, and enzyme distribution. Both chronological changes of striatal damage and the absence of neurological sequelae in this patient suggest the possibility that anti-epileptics and a calcium antagonist played a neuroprotective role in the acute cyanide intoxication.

[Maintenance chemotherapy using UFT and FT for gynecological malignant tumors. The Gunma Prefectural Society for Study of Chemotherapy for Gynecological Cancer]

The Gunma Prefectural Society for Study of Chemotherapy for Gynecological Cancer made a comparative study on postoperative supplementary chemotherapy including UFT and FT-E for gynecological malignant tumors. The number of cases registered totaled 182, which was broken down into ovarian cancer 53 cases, uterine cervical cancer 89 cases and endometrial cancer 30 cases. Complete cases among them consisted of ovarian cancer 53 cases, uterine cervical cancer 86 cases and endometrial cancer 27 cases for a total of 166 cases. Ovarian cancer was stratified into the completely and incompletely removed cases, uterine cervical cancer into postoperative non-irradiated and irradiated cases and endometrial cancer into the positive metastasis (+) group and negative metastasis (-) group. Then the UFT administration group and FT-E administration group were compared for postoperative survival. There were control groups for both ovarian and endometrial cancer. UFT administration showed a significant improvement in the survival rate (P < 0.05) compared to the FT-E administration group in the cases of ovarian cancer completely removed and the cases of endometrial cancer irradiated after operation. No significant difference was observed between other groups compared. The incidence of side effects was 20.6% (20/97) in the UFT administration group and 3.6% (2/55) in the FT-E group. Neither group showed any serious side effects.

Residual effects of repeated administration of triazolam and nitrazepam in healthy volunteers

The residual effects of hypnotics were investigated with a long-acting (nitrazepam) and a short-acting (triazolam) benzodiazepine hypnotic in 8 male volunteers. Subjects received placebo, nitrazepam 5 mg, or triazolam 0.25 mg for 7 consecutive nights in a random-order, double-blind crossover design. Daytime sleepiness, psychomotor performance, EEG activity and standing steadiness were assessed in the morning after 1, 4, and 7 days of drug treatment. Plasma concentrations of nitrazepam and triazolam were also assayed. The concentration of nitrazepam increased gradually during the course of treatment and was associated with residual sedative effects on days 4 and 7. Nitrazepam produced no apparent psychomotor impairments in these studies. On the other hand, there was no evidence of drug accumulation after triazolam administration and triazolam showed no residual sedative effects or residual impairment of psychomotor performance during the experiment. Thus, short-acting hypnotics may have an advantage over long-acting hypnotics in terms of producing less residual sedative effects during chronic treatment.