Effects of a calcium channel blocker, manidipine, on insulin sensitivity in essential hypertensives

This study was designed to investigate the effects of the calcium channel blocker manidipine on insulin-dependent glucose uptake (insulin sensitivity) and insulin action to renal sodium handling and pressor systems in essential hypertensive (EHT). Seven EHT were hospitalized and a 2-h euglycemic hyperinsulinemic glucose clamp was performed in a fasting condition before and after 2 weeks administration of manidipine (20 mg/day). Insulin sensitivity was evaluated as M-value calculated from the infusion rate of glucose. Manidipine administration decreased mean blood pressure and increased M-value significantly in EHT. Before the manidipine treatment, hyperinsulinemia during the clamp induced a decrease of urinary sodium excretion and increases of plasma norepinephrine and plasma renin activity in EHT. After manidipine treatment, however, hyperinsulinemia induced natriuresis and did not augment the pressor systems activity. Thus, the calcium channel blocker improved insulin resistance as assessed by glucose clamp technique in EHT. Suppression of augmented renal sodium reabsorption and pressor system activities of insulin may be connected with the hypotensive mechanisms and the natriuresis caused by calcium channel blockers.

Sequential analysis of recurrent calcium calculi by infrared spectroscopy

BACKGROUND

While the incidence of calcium urolithiasis increases, the precise mechanism of calcium oxalate stone formation is still controversial. Is the composition of a recurrent calcium oxalate stones always the same as previous ones? There are few reports that specifically address the question by study of sequential changes of the composition of recurrent calcium calculi.

METHOD

From our medical records 70 patients with a history of two or more recurrent episodes of calcium oxalate stone disease were selected and the analyses of 190 stones were reviewed. Infrared spectroscopic analysis was done using a Perkin Elmer 1740 spectrophotometer.

RESULTS

Calcium oxalate monohydrate were detected in 63 stones, calcium oxalate dihydrate in 12, calcium oxalate monohydrate mixed with dihydrate in 28, calcium oxalate monohydrate mixed with calcium phosphate in 30, calcium oxalate dihydrate mixed with calcium phosphate in 20, calcium oxalate monohydrate mixed with dihydrate and calcium phosphate in 20, calcium oxalate monohydrate mixed with dihydrate and calcium phosphate in 37. Alterations of stone components during follow-up were found in 43 stones from 40 patients. The shift of a main composition from calcium oxalate monohydrate to calcium oxalate dihydrate was found in 24 stones and vice versa in 19 stones.

CONCLUSIONS

Sequential changes of the compositions of recurrent calcium calculi are highly likely to occur with time in individual recurrent calcium stone formers. Calcium oxalate monohydrate was a most common component of the studied recurrent calcium stones.

Differences in midazolam-induced breathing patterns in healthy volunteers

Sex differences, and the influence of drug dosage and additional upper airway obstruction were studied in midazolam-induced breathing patterns and sedation in 30 healthy volunteers (8 males and 22 females). After administration of 0.1 mg.kg-1 midazolam (8 male and 8 female subjects), the rib cage (RC) motion increased in 6 males and the abdominal wall (ABD) motion and SaO2 decreased in all males. In contrast, the RC and ABD motions and SaO2 decreased in all females. Snoring and loss of consciousness occurred in 7 males and in 2 females. There were significant differences in the RC motion, SaO2, the incidence of snoring and the sedative state between male and female subjects. A bolus dose of 0.5 mg of flumazenil completely antagonized the sedative effect of midazolam and restored the breathing pattern, whereas it did not completely restore SaO2. A higher dose (0.2 mg.kg-1) of midazolam was administered to an additional 8 females. It caused a loss of consciousness in all subjects and increased the RC motion in only one subject. Partial obstruction of the nasal cavity was effected with cotton balls in the remaining 6 females who were sedated with 0.1 mg.kg-1 midazolam. An increase in the RC motion occurred similar to that observed in males. These findings suggest a difference in midazolam-induced sedation and breathing patterns between male and female subjects with midazolam administration on a mg.kg-1 basis.

Effects of sevoflurane on respiratory activities in the phrenic nerve of decerebrate cats

Although the depressive effect of sevoflurane on ventilation has been reported, its potency and mode of action on the neural respiratory activity is still unclear. Therefore, the effects of sevoflurane on the phrenic nerve discharge and the respiratory timing were compared with those of halothane. The efferent activity of the phrenic nerve was recorded from decerebrate, un-anesthetized and artificially ventilated cats, and its power spectrum was calculated. The inspiratory and expiratory periods were measured. Sevoflurane and halothane of the doses of 0.5-1.5 MAC were inhaled for 15 min. With 0.5 MAC, sevoflurane decreased the total power and two dominant spectral components of the high-frequency oscillation and medium-frequency oscillation in the power spectrum. With the same MAC dose, halothane had a greater depressive effect in a normocapnic condition with the vagus nerves being intact. In a state of hypercapnia or after vagotomy, the effect of halothane was considerably attenuated whereas that of sevoflurane remained unaltered. Halothane increased the neural respiratory rate much more than sevoflurane in both normocapnic and hypercapnic states. Vagotomy significantly weakened the effect of halothane to increase the respiratory rate but did not modify the effect of sevoflurane. With 1.0-1.5 MAC, both anesthetics severely decreased the phrenic power spectra and the potency difference became indistinct. The present findings demonstrate that sevoflurane has a weaker depressive effect on the respiratory nerve discharge and a smaller effect on the neural respiratory rate than halothane when the effects of 0.5 MAC were compared.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of restricted feeding on the light-induced body weight change and locomotor activity in the Djungarian hamster

To investigate the role of food intake in seasonal body weight changes in the Djungarian hamster, we divided animals, which had minimum body weights after 18 wk in SD, into ad-lib feeding and restricted feeding groups under a long day (LD) and a short day (SD) photoperiods. In the ad-lib feeding groups, body weight and food intake increased in parallel after 3 wk under LD and after 6-7 wk in SD because of photorefractoriness. In the restricted feeding groups, almost all animals moved around furiously (food-seeking activity) when they came to consume all the food provided at 2-3 wk of the treatment in LD and after several weeks in SD with the initiation of photorefractoriness, and ended up with death. In the restricted feeding groups, body weight increase was not observed. The furious food-seeking activity in the restricted groups and the increase of body weight specific food intake (food intake/body weight) in the ad-lib feeding groups might reflect the increased requirement for food. This increase of requirement for food seems to be one of the critical factors regulating the seasonal body weight change.

Changing patterns of vitellin-related peptides during development of the cattle tick Boophilus microplus

The major components of protein extracts from the cattle tick Boophilus microplus eggs and larvae of various ages were characterized by molecular sieving chromatography, ion exchange chromatography and SDS-PAGE. The fractions analysed showed a changing chromatographic pattern development. A serum raised against the components of a fraction showing characteristics of vitellin strongly reacted in Western blots with the major peptides of extracts from eggs, larvae, gut and ovary. Comparison of patterns obtained by electrophoresis in non-denaturing PAGE, stained with Coomassie blue or with benzidine/hydrogen peroxide, revealed that the major proteins of these extracts are haemoproteins, possibly in different aggregation states or heterogeneous in composition.

[A transient sinus arrest after right stellate ganglion block--assessment of autonomic function by heart rate spectral analysis]

We experienced a case of sinus arrest probably induced by right stellate ganglion block (SGB). A healthy medical student volunteered in our study of the cardiac autonomic nervous system and received the SGB. After the Holter ECG had been attached, the SGB was performed with mepivacaine 8 ml. Horner's sign was observed after about 3 minutes. A transient (15 s) sinus arrest occurred suddenly after about 6 minutes of the tilt test probably due to a vasovagal reflex, and the subject lost consciousness. From spectral analysis of the Holter ECG recording, the right SGB may be closely involved in the induction of the sinus arrest. Our present case suggests that sinus arrest may occur if a patient stands up after right SGB.

Clinical features of patients with anorexia nervosa: assessment of factors influencing the duration of in-patient treatment

We investigated that factors affecting the duration of in-patient treatment of patients with anorexia nervosa by comparing pretreatment clinical features with the length of hospitalization in 55 patients. Only patients who had completed the entire course of treatment were included in our analysis. Longer hospitalization was correlated with: poor social adaptation; anxiety and/or personality disorders before onset; older age at onset; older age at admission to our hospital; lower minimum body weight after onset; lower body weight at admission; longer duration of illness; frequent previous hospital treatment and/or history of in-patient treatment for anorexia nervosa or other somatic disorders after onset; habitual stimulant (alcohol, coffee and/or cigarettes) abuse; and a history of stealing after onset. Step-wise regression analysis revealed that minimum body weight after onset and age at admission explained 47% of the variance in the duration of in-patient treatment. We also describe the nature of in patient treatment typically offered to patients with anorexia nervosa in Japan.

Circadian rhythms of corneal mitotic rate, retinal melatonin and immunoreactive visual pigments, and the effects of melatonin on the rhythms in the Japanese quail

We investigated circadian ocular rhythms in the Japanese quail, Coturnix coturnix japonica. The birds were placed under light-dark cycles (LD 12:12), constant light (LL) and constant darkness (DD), and the retinas were dissected out at four-hour intervals throughout 24 h. Following measurements were performed. (1) Melatonin content in the retina was measured by radioimmunoassay. It was low in light and several folds higher in darkness under LD 12:12. The rhythm continued in DD, but disappeared in LL. (2) Mitotic figures in the corneal epithelium were counted. Similar rhythms to the melatonin content were observed in the corneal mitotic rate with a slight phase delay. (3) The retinas were fixed at 4-h intervals and immunostained with anti-bovine rhodopsin serum and anti-chicken iodopsin monoclonal antibodies. The outer segments of photoreceptor cells were stained intensively throughout 24 h in LD 12:12, LL and DD. In contrast, the stainability of the locus close to the outer limiting membrane where the Golgi apparatus exists changed diurnally. Scores showing the ratio of cells with positive staining indicated high values from 4 h after the onset of light to the beginning of dark phase under LD 12:12. The values were high throughout 24 h in LL and intermediate or low in DD. (4) To investigate the effect of melatonin on the corneal mitotic rate and visual pigments at the Golgi region, melatonin was injected into one eye and saline into the contralateral eye. Melatonin induced a phase advance in the corneal mitotic rate under LD 12:12, but did not induce a rhythm under LL.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of angiotensin receptor antagonist and angiotensin converting enzyme inhibitor on insulin sensitivity in fructose-fed hypertensive rats and essential hypertensives

This study was designed to investigate the effects of angiotensin II (AII) receptor antagonist and angiotensin converting enzyme (ACE) inhibitor on insulin resistance, and the mechanism by which ACE inhibitor improves insulin-dependent glucose uptake (insulin sensitivity) in an insulin-resistant hypertensive rat model (fructose-fed rats, FFR) and in essential hypertensives (EHT). Male Sprague-Dawley rats were fed on fructose-rich or standard chow for 4 weeks and treated either with 10 mg/kg/day of delapril (n = 8), 1 mg/kg/day of TCV-116 (AII receptor antagonist; n = 13), or vehicle (n = 9) for the latter 2 weeks. Steady-state plasma glucose (SSPG) was measured with the subjects in the conscious state; simultaneously, we infused insulin (2.5 mU/kg/min) and glucose (8 mg/kg/min) to determine insulin sensitivity in each group. Thirteen EHT were hospitalized and the 2-h euglycemic hyperinsulinemic glucose clamp (GC) method was performed in a fasting condition before and after 2 weeks' administration of TCV-116 (8 mg/day) in 7 EHT and of delapril (120 mg/day) in 6 EHT. Insulin sensitivity was evaluated as M-value calculated from the infusion rate of glucose. Mean blood pressure (MBP) was higher in FFR (137.7 +/- 73.8 mm Hg, P < .05) compared to controls (120.8 +/- 2.7 mm Hg), and was lower in both the delapril (108.1 +/- 6.3 mm Hg, P < .05) and TCV-116 (112.8 +/- 4.3 mm Hg, P < .05) groups than in FFR.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of bupivacaine on Na+ and Ca2+ currents in single canine ventricular cells]

The effects of bupivacaine on Na+ and Ca2+ currents in single canine isolated left ventricular cells were examined using whole-cell voltage clamp technique to reveal the mechanism of its negative inotropism. The cells were isolated by enzymatic dispersion and superfused in an oxygenated Tyrode's solution. Bupivacaine 10(-6) M decreased the amplitude of INa and delayed the peak time. These effects were dose and frequency dependent. At a concentration of 10(-3) M, bupivacaine abolished INa. Meanwhile, bupivacaine did not modify ICa at a concentration of 10(-6) M. At 10(-5) M bupivacaine, the amplitude of ICa was depressed by 22% and the depression was dose dependent. These results suggest that low concentration (10(-6) M) of bupivacaine depresses contraction, by reducing intracellular Ca2+ secondary to reduction in intracellular Na+ activity and the Na+-Ca2+ exchange mechanism. At higher concentrations, the reduction in contraction caused by bupivacaine may result partly from a reduced influx of Ca2+.

Testosterone regulation of platelet and vascular thromboxane A2 receptors

Testosterone has been implicated as a risk factor for cardiovascular diseases and thromboxane A2 (TXA2) plays a role in these diseases. We tested the notion that testosterone regulates the expression of TXA2 receptors in platelets and vascular smooth muscle. Testosterone significantly increased the density of TXA2 receptors in cultured rat aortic smooth muscle and human erythroleukemia cells, a megakaryocyte-like cell. Treatment of rats with testosterone resulted in a significant increase in platelet and aortic TXA2 receptor density and increased responsiveness to TXA2 mimetics. We conclude that testosterone regulates the expression of TXA2 receptors.

Auditory brainstem response (ABR) peak amplitude variability reflects individual differences in cochlear response times

Previously, it was shown [Don et al., J. Acoust. Soc. Am. 94, 2135-2148 (1993)] that cochlear response times are gender specific and about 13% shorter in females than in males. It is also suggested that one of the possible reasons click-evoked auditory brainstem response (ABR) waveforms recorded from females are better defined and have larger amplitudes than those of males is due to a sex difference in cochlear response times leading to better synchronization of the cochlear output across the frequency regions. Variability in cochlear response times would also lead to variability in click evoked ABR amplitudes. The high-pass noise masking derived ABR technique was used to investigate the effect of normalizing the individual temporal variability at the neural and cochlear levels. This involved adjusting for differences in neural conduction time (I-V delay) by a compression or expansion of the derived ABR waveforms and by adjusting for differences in cochlear response times by a shift of the derived ABR waveforms. A summation of the compressed and shifted ABRs results in a normalized unmasked ABR waveform that can then be compared for amplitude variability with the unprocessed unmasked ABRs. Compensation for the neutral I-V variability had little effect while compensation for cochlear response times, particularly the delay between the 5.7- and 2.8-kHz regions, greatly affected the amplitude of wave V of the compounded ABR. This work provides a better understanding of the significant relationship between cochlear response times and variability of the ABR peak amplitudes.

Restoration of microfilament bundle organization in v-raf-transformed NRK cells after transduction with tropomyosin 2 cDNA

The syntheses of tropomyosin (TM) isoforms, especially those of TM1 and TM2, were suppressed in v-raf-transformed NRK cells. To test whether restoration of one of the suppressed TM expressions affects cellular phenotypes of v-raf-transformed NRK cells, the cells were transduced with mouse fibroblast TM2 cDNA by retrovirally mediated DNA transfer method. Clones expressing the inserted TM2 cDNA and accordingly higher amounts of TM2 than the parental and control clones displayed a flatter morphology which was accompanied by partial restoration of microfilament organization, indicating that restoration of one of the diminished TM isoforms results in reorganization of microfilament bundles. However, no significant decrease in cell growth rate and the ability to grow in soft agar was observed in the TM2 cDNA-transduced cells.

Psychobehavioral and immunological characteristics of adult people with chronic fatigue and patients with chronic fatigue syndrome

The psychobehavioral responses and cellular immune function were investigated in healthy people (control, N = 21), adult people with chronic fatigue (fatigue-non-CFS group, N = 24), and patients with chronic fatigue syndrome (CFS, N = 10). Based on psychobehavioral responses, the fatigue-non-CFS group had low general activity levels (p < .05) and slightly depressive tendencies (p < .01) compared with the control. They had many life event stresses (p < .05) and sleep disturbances (p < .01), and they could not cope appropriately with stresses. The fatigue-non-CFS group also showed significantly lower natural killer (NK) cell activity (p < .01) and decreased numbers of CD16+ and CD56+ cells (p < .05). Compared with the fatigue-non-CFS group, patients with CFS had higher degrees of physical fatigue (p < .01) and more life event stresses (p < .05). They had lower general activity levels and social introversion. They were also in a depressive state. NK cell activity and the numbers of CD16+ and CD56+ cells were significantly reduced in patients with CFS (p < .01). These findings suggest that adult people with chronic fatigue may be in an intermediate state between the healthy control and patients with CFS in terms of psychobehavioral responses and low NK cell activity. We observed three cases in such an intermediate state in whom CFS subsequently developed.

Does insulin resistance participate in an impaired glucose tolerance in primary aldosteronism?

It has been reported that glucose intolerance is occasionally found in primary aldosteronism. In this study, we measured insulin sensitivity by the euglycaemic hyperinsulinaemic glucose clamp technique and ability to release insulin by 75 g oral glucose tolerance test (OGTT) in primary aldosteronism. Seven patients with primary aldosteronism (PA) (53.7 +/- 3.4 years; mean +/- SEM) and eight normotensive subjects (NS) (57.5 +/- 2.6 years) were employed in this study. The two-hour euglycemic hyperinsulinaemic glucose clamp technique was performed in seven PA before adrenalectomy, six PA after adrenalectomy and eight NS. The 75 g OGTT was also done in five PA before and after adrenalectomy and eight NS. The mean rate of glucose infusion to maintain euglycemia for the last 30 minutes of the clamp technique was used as an indicator of insulin sensitivity (M-value). The total blood glucose levels during 75 g OGTT (area under the curves) (sigma blood glucose) were significantly higher in PA than those in NS, and the total insulin levels during 75 g OGTT (area under the curves) (sigma IRI) were significantly lower in PA than those in NS. After adrenalectomy in PA, blood glucose levels were significantly decreased and IRI were significantly increased compared with the normal range. There was a significant positive correlation (P < 0.05, r = 0.71) between serum potassium levels and IRI in PA which were determined before and after adrenalectomy. In PA, M-values (240.7 +/- 14.6 mg/m2/min) were significantly higher than those in NS (199.0 +/- 12.3 mg/m2/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of tetanic stimulation on subsequent train-of-four responses at various levels of vecuronium-induced neuromuscular block

Tetanic stimulation influences subsequent neuromuscular responses. In addition, the tetanus-induced changes in neuromuscular responses differ according to the level of neuromuscular block at which tetanic stimulation is delivered. We studied the tetanus-induced effect on subsequent train-of-four (TOF) responses at various levels of vecuronium-induced neuromuscular block in 45 anaesthetized patients. Tetanic stimulation was applied when a twitch height of T1 returned to 25%, 50% and 75% of its control twitch height (T0) (groups 1, 2 and 3, respectively) after administration of vecuronium 0.1 mg kg-1. Maximum post-tetanic percentage increases in TOF responses in groups 1, 2 and 3 were 257 (SD 119)%, 107 (75)% and 68 (54)% for T1/T0 (P < 0.001 for group 1 vs 2; P < 0.001 for group 1 vs 3) and 535 (259)%, 421 (213)% and 292 (171)% for T4/T1 (P < 0.01 for group 1 vs 3), respectively. Durations of post-tetanic increases in TOF responses in groups 1, 2, and 3 were 52 (19) s, 37 (14) s and 32 (13) s for T1/T0 (P < 0.05 for group 1 vs 2; P < 0.01 for group 1 vs 3) and 53 (17) s, 46 (15) s and 35 (12) s for T4/T1 (P < 0.05 for group 1 vs 3), respectively. These data suggest that the tetanus-induced effect on subsequent TOF is more apparent and lasts longer at greater degrees than at lesser degrees of neuromuscular block.

[Osteoporosis after menopause and oophorectomy]

Characteristics of osteoporosis occurring after menopause and oophorectomy are described. Changes in hormone dynamics induced by menopause or oophorectomy lead to high metabolic turnover of bone, characterized by increased bone formation and resorption. The increase in bone resorption surpasses that of bone formation, resulting in decreased bone mineral density (BMD). Even before the onset of menopause, a transient decrease in estrogen concentrations can produce decreases in BMD that are comparable to those occurring after menopause or oophorectomy. Long-term observation of women undergoing premature menopause indicates that BMD progressively continues to decline in association with high bone metabolic turnover. There was no significant difference between BMD, 3 years after menopause, compared with that 3 years after oophorectomy, a time when the effect on BMD are fully evident. These findings indicate that osteoporosis, associated with either menopause or oophorectomy, can be managed in the same manner in a clinical setting.

Cutaneous iontophoretic application of condensed lidocaine

The purpose of this study was to determine whether iontophoretic application of high concentrations of lidocaine, with the same current, would produce cutaneous local anaesthesia rapidly enough for clinical practice. Twenty healthy volunteers, 17 male and three female, were selected for study. After five-minute or ten-minute iontophoresis using lidocaine 4, 10, 20, 30, 50%, we assessed the response to pin prick with a 27-gauge sterile needle inserted to the depth of 2 mm at five random locations in the iontophoretically-stimulated area. Also, plasma lidocaine concentrations were measured in the venous blood samples which had been taken from three male subjects, at 3, 10, and 30 min after iontophoresis with lidocaine 50%. The pain score after five-minute iontophoresis was higher than that after ten-minute iontophoresis, using each concentration of lidocaine (P < 0.001), whereas the pain scores had no correlation with lidocaine concentration within five-minute and ten-minute iontophoresis groups, respectively (P: NS). On the other hand, plasma lidocaine concentration was < 1.0 micrograms.ml-1 in all samples. No side effects other than erythema were observed after iontophoresis using high concentrations of lidocaine up to 50%. These results showed that by increasing the lidocaine concentration of the applied solution up to 50%, the application time of iontophoresis cannot be reduced from ten to five minutes without losing analgesic effect, although iontophoresis itself can be performed with safety.

[Flumazenil antagonism of midazolam-induced respiratory depression]

Flumazenil, a benzodiazepine antagonist, reliably reverses midazolam-induced sedation, but its effect on respiratory depression has not been clarified completely. Ten healthy male volunteers received midazolam 0.1 mg.kg-1. Then they received flumazenil 0.5 mg (n = 9) and 1.0 mg (n = 1), intravenously. Rib-cage (RC) and abdominal wall (ABD) movement was measured by mercury-in-silastic strain gauge. Nasal air flow (FLOW), genioglossal electromyogram (EMG) and oxygen saturation (SaO2) were recorded simultaneously. Midazolam caused significant increases of RC movement and respiratory rate, and decreases of ABD movement, FLOW, EMG and SaO2. After administration of flumazenil, although respiratory rate returned to the pre-midazolam values, RC movement decreased on the contrary. ABD movement, FLOW, EMG, SaO2 did not recover to the pre-midazolam values. These data suggest that flumazenil 0.5 mg reverses midazolam-induced sedation completely, but is partially effective for some parameters related to respiratory depression.

Morphometrical analysis of cystadenolymphoma (Warthin's tumor). Subclassification and characterization of the lymphoid stroma in comparison with gastric lymphoid follicles

Morphometrical analysis was applied to cystadenolymphoma (Warthin's tumor, adenolymphoma: CAL). By quantitative analysis of tissue sections, the examined cases were divided into three subtypes according to the ratio of the lymphoid stroma (LS) to the whole tissue: type I "stroma-rich type", the LS of this type was more than 57% of the whole tissue; type II "typical type", the LS of this type was 37% to 56% of the whole tissue; and type III "stroma-poor type", the LS of this type was less than 36% of the whole tissue. The average age of the patients in subtypes I, II and III was 57.7, 68.0, and 62.4 years, respectively. The age of the patients with type I CAL was significantly lower than that of those with type II CAL. In many type II cases, a reticular distribution of IgE in the germinal centers was frequently observed. From an analysis of the sections immunohistochemically stained with monoclonal antibodies to B and T cells, there appeared to be a trend that the greater the percentage of the LS to the whole tissue, the lower the ratio of B cell region to the LS. In contrast to CAL, an analysis of the change of the ratio of B cell region to the lymphoid follicles (LF) seen in the gastric mucosa of patients with chronic gastritis showed that the larger the volume of LF, the higher the ratio of the B cell region to the entire LF.(ABSTRACT TRUNCATED AT 250 WORDS)