Telecommunication and international health research

Telecommunication will revolutionize how international medical research is completed. It is faster, more accurate, less expensive, and potentially more accessible than all other existing modes of communication. It is time for medical scientists to come into the age of electronic communication.

Long-lasting hypotensive and antihypertensive effects of a new 1,5-benzothiazepine calcium antagonist in hypertensive rats and renal hypertensive dogs

The hypotensive effect of a new 1,5-benzothiazepine derivative, TA-3090 ((+) (2S,3S)-3-acetoxy-8-chloro-5-(2-(dimethylamino)ethyl)-2, 3-dihydro-2-(4-methoxyphenyl)-1,5-benzothiazepin-4-(5H)-one maleate), was studied in various models of experimental hypertension. In conscious spontaneously hypertensive rats (SHR), TA-3090 at a dose of 3 mg/kg p.o. or more caused significant hypotension. The effect was long-lasting, being observed for more than 8 h and 24 h at doses of 30 and 100 mg/kg p.o., respectively. Heart rate was not increased with doses up to 30 mg/kg p.o. TA-3090 like diltiazem, showed more potent hypotensive effect in SHR than in Wistar Kyoto rats (WKY). The enhancement of the hypotensive effect in SHR was more evident with TA-3090 and diltiazem than with 1,4-dihydropyridine calcium antagonists (1,4-DHPs). The enhanced hypotensive effect of TA-3090 was also observed in deoxycorticosterone acetate (DOCA)-salt hypertensive rats in which the minimum hypotensive dose of TA-3090 was 1 mg/kg p.o. In SHR, reflex tachycardia induced by TA-3090 was smaller than those induced by 1,4-DHPs, while diltiazem decreased the heart rate. In WKY, all calcium antagonists except diltiazem at a low dose (30 mg/kg p.o.) increased the heart rate. Development of hypertension in young SHR was significantly suppressed by chronic treatment with TA-3090 at a daily dose of 10 mg/kg p.o. or more. The antihypertensive effect of TA-3090 was also observed by administration in the diet in matured SHR. In addition, TA-3090 exhibited a dose-related natriuretic but not kaliuretic effect in SHR at doses slightly higher than the hypotensive ones.(ABSTRACT TRUNCATED AT 250 WORDS)

Ampicillin concentrations in human dental granuloma after a single oral administration of talampicillin

Ampicillin concentrations in human serum and dental granulomas of 31 patients were determined after a single oral dose of talampicillin (equivalent to 500 mg of ampicillin) was administered to each. The specimens were taken at 1.5, 2.0, 2.5, 3.0, and 3.5 h after the administration of talampicillin. The mean peak ampicillin concentrations in serum and dental granulomas occurred at identical times, 2.5 h, and were 8.29 micrograms/ml (range, 1.81 to 13.20 micrograms/ml) and 2.94 micrograms/g (range, 1.14 to 7.16 micrograms/g), respectively. The mean dental granuloma/serum ampicillin concentration ratio at the peak time (2.5 h) was 0.42 (range, 0.29 to 0.56). Ampicillin concentrations in dental granulomas exceeded most of the MICs for the bacteria commonly isolated from odontogenic infection.

Ampicillin concentrations in human serum and periodontal membrane following a single oral administration of talampicillin

1. Ampicillin concentrations in human serum and periodontal membrane after a single oral administration of talampicillin (500 mg) were assayed by the agar diffusion (paper disc) method. 2. The peak times of serum and periodontal membrane were identical, being 150 min after administration. 3. The peak concentrations of serum and periodontal membrane were 7.81 micrograms/ml and 4.11 micrograms/g, respectively. 4. The mean ratio of periodontal membrane to serum concentration at the peak time was 0.53.

Extraneuronal accumulation of isoproterenol in atria and ventricle of perfused rat heart

Extraneuronal accumulation of isoproterenol in atria and ventricle of perfused rat heart was investigated. Rat hearts were perfused with various concentrations of 3H-isoproterenol for 30 min in the absence and the presence of catechol-O-methyltransferase (COMT) inhibitor (tropolone). When COMT was intact, the accumulation of 3H-isoproterenol in both atria and ventricle after perfusion with low concentration of 3H-isoproterenol (0.01 to 1 mumol/l) was less than that of perfusing concentration; the tissue/medium ratio (T/M) of isoproterenol for artia was lower than that for ventricle. The T/M of isoproterenol after perfusion with 10 and 20 mumol/l of 3H-isoproterenol were 0.94 and 1.76 for atria and 3.25 and 2.95 for ventricle, respectively. When COMT was inhibited by tropolone, the T/M increased 6.3-9.0 folds for atria and 5.1-6.7 folds for ventricle after perfusion with 3H-isoproterenol (0.01 to 1 mumol/l). From these results, it was concluded that both atria and ventricle of the rat heart have an extraneuronal O-methylating system as reported in rat whole heart, and was suggested that there might be different capacities of extraneuronal uptake and COMT between them.

Inhibition by epidermal growth factor of glucocorticoid-induced epidermal alpha-type keratinization of chick embryonic skin cultured in the presence of delipidized fetal calf serum

When a 13-day-old chick embryonic tarsometatarsal skin was cultured for 4 days in medium containing hydrocortisone (20 nM) and 5% delipidized fetal calf serum (FCS), epidermal growth factor (EGF, 100 ng/ml) decreased epidermal DNA content 42% and inhibited epidermal DNA synthesis 87%. Tonofilament bundles within the basal and intermediate cells of the EGF-treated epidermis were not as conspicuous as those in the glucocorticoid-induced keratinized epidermis, and the upper region of the EGF-treated epidermis did not form either the filament bundles or the electron-dense amorphous masses seen in the cytoplasm of the glucocorticoid-induced keratinized layer. EGF stimulated degradation of glucocorticoid-induced alpha-keratin. Furthermore, EGF caused a twofold increase in glucocorticoid-induced epidermal transglutaminase activity and in the amount of epidermal glucocorticoid receptor. In the absence of FCS, however, EGF did not inhibit steroid-induced alpha-type keratinization and did not affect either steroid-induced epidermal transglutaminase activity or amount of epidermal glucocorticoid receptor. Hence, the effect of EGF on glucocorticoid-induced epidermal transglutaminase activity was observed only in the presence of delipidized FCS and might be supported by an increase in the amount of glucocorticoid receptor.

Nitroglycerin-sensitive and -resistant contractions mediated by receptor-operated calcium channels in rabbit ear artery

In isolated rabbit ear arteries incubated in a Ca2+-free medium with EGTA and nifedipine in the presence of norepinephrine, serotonin or histamine, an addition of Ca2+ induced a tonic contraction which is due to Ca2+ entry through receptor-operated Ca2+ channels (ROCs). Nitroglycerin (10(-4) M) significantly inhibited the ROCs-dependent contractions produced by serotonin or histamine, but failed to inhibit the ROCs-dependent contraction by norepinephrine. These results suggest the possible existence of two types of receptor-operated Ca2+ channels in rabbit ear artery.

Effects of NC-1300 and its degradation products on gastric secretion and HCl.ethanol-induced gastric lesions in rats

The proton pump inhibitor NC-1300 has antisecretory and cytoprotective activities in rats. The compound is labile at an acidic pH and degrades into various products. We attempted to identify these products after treatment at different pHs in vitro using HPLC. We also examined whether (A) NC-1300 treated at acidic pHs loses its efficacy on gastric secretion and gastric lesions and (B) whether the degradation products of NC-1300 have pharmacological effects in rats. The acidic degradation products proved to be mainly NC-1300-sulfide and partly o-dimethylaminobenzylalcohol (o-DMABA) and benzimidazole (BI). NC-1300, pretreated at pH 1.0, 1.25 or 1.5 for 30 min and given p.o. at 30 mg/kg, significantly inhibited gastric acid secretion in pylorus ligated rats and prevented development of HCl X ethanol-induced gastric mucosal lesions. The degree of antisecretory and cytoprotective activities by NC-1300 treated at pH 1.5 was almost the same as that obtained by NC-1300 treated at pH 7.0. NC-1300-sulfide or mixtures of degradation products, with or without unchanged NC-1300, also significantly inhibited the gastric acid secretion and lesion formation. We conclude that while NC-1300 degrades at low pHs, the compound treated at such a low pH exerts pharmacological effects presumably by the unchanged form of NC-1300 and/or its degradation products.

Effects of antiarrhythmic drugs on the extraneuronal accumulation of isoprenaline in perfused rat hearts

The effects of class I, II, III and IV antiarrhythmic drugs (as classified by Vaughan Williams 1974), tetrodotoxin and beta 2-adrenoceptor antagonists on the extraneuronal accumulation of isoprenaline were examined in isolated rat hearts perfused with 3H-isoprenaline (1 mumol/l) and tropolone (100 mumol/l) for 30 min at a constant flow rate (6.5 ml/min) at 40 degrees C. Quinidine (class I), verapamil (IV), diltiazem (IV), dilazep (IV), nifedipine (IV), tetrodotoxin and butoxamine, at a concentration of 10 mumol/l, significantly decreased the extraneuronal accumulation of isoprenaline. The present study demonstrated that quinidine (class I) and all of the calcium channel blockers (class IV) had potent inhibitory effects on the extraneuronal accumulation of isoprenaline. The concentrations of these drugs needed for this decrease were nearly comparable to those needed to suppress isoprenaline-tropolone-induced ventricular fibrillation (Sono et al. 1985a). The antiarrhythmic effects of quinidine and calcium channel blockers in this experimental model may be partly due to a decrease in the extraneuronal accumulation of isoprenaline.

Ampicillin concentrations in human serum, gingiva, mandibular bone, dental follicle, and dental pulp following a single oral administration of bacampicillin

Ninety-six patients who underwent the extraction of impacted mandibular third molars in a nonfasting state were given a single oral dose of bacampicillin preoperatively. Specimens of serum from venous blood (n = 107), gingiva (n = 57), mandibular bone (n = 68), dental follicle (n = 56), and dental pulp (n = 43) were obtained during the operation and assayed for ampicillin content. The mean peak concentrations in serum, gingiva, mandibular bone, dental follicle, and dental pulp all occurred approximately 90 minutes after administration. The concentration ratios of the tissues to the corresponding serum at the peak time were 0.50, 0.20, 0.34, and 0.61, respectively. Bacampicillin showed good absorption by the intestine, and sufficient concentrations of the resulting metabolite, ampicillin, were found in the oral tissues.

Ampicillin concentrations in human serum and periodontal membrane following a single oral administration of bacampicillin

Ampicillin concentrations in human serum and periodontal membrane after a single oral administration of bacampicillin (500 mg) were assayed by the agar diffusion (paper disc) method. The peak times of serum and periodontal membrane were nearly identical, being approx. 90 min after administration. The peak concentrations of serum and periodontal membrane were 12.81 micrograms/ml and 6.97 micrograms/g, respectively. The concentration ratio of periodontal membrane to serum at the peak time was 0.56.

Experimental neurogenic bladder in rats and effect of Robaveron, a biological prepared from swine prostate, on it

An experimental neurogenic bladder was induced in rats by an intraspinal injection of 10% phenol-glycerin solution. The functional and biochemical changes in the bladder were studied in vivo and ex vivo, and the effect of Robaveron, a biological prepared from swine prostate, on these changes were examined. The forced voiding pressure in the control rats which had been caused by the neurogenic bladder was reduced to 1/4-1/5 that of the intact animals. Robaveron recovered a decrease in the pressure, and the effect of 150-250 mg/kg, p.o., corresponded nearly to that of 40 mg/kg, i.m. In the ex vivo study with the strips of isolated neurogenic bladder muscle, the time required to cause 50% of the maximum contraction by transmural electric stimulation prolonged to about four times that of the intact one. Such a prolongation was recovered by Robaveron in a dose-dependent fashion, and the effect of Robaveron given p.o. corresponded to about 1/6 that of the drug given i.m. No change in Ca2+-influx, was found, although Ca2+-efflux was inhibited in the strip of neurogenic bladder muscle. Such an inhibition was significantly relieved in that of animals treated with Robaveron. In the neurogenic bladder rat, the ratio of bladder weight to body weight increased, and the activities of total ChE and AChE in the bladder muscle decreased, on which Robaveron did not show any influence. Phasic and tonic contractions in the strips of intact rat bladder and guinea pig ileum were inhibited by La3+, particularly phasic response in both the strips. Robaveron recovered the inhibition in a dose-dependent fashion. The present study suggests that the urinary dysfunction in neurogenic bladder may be caused not only by nervous disorders but also by changes in the bladder muscle itself. Robaveron was found to be effective for most of such changes. These findings may support the clinical efficacy of Robaveron for improving the attenuated bladder function.

A new model of ventricular fibrillation induced by isoprenaline and catechol-O-methyl transferase inhibitor at a high perfusion temperature in isolated rat hearts

Isolated rat hearts were perfused with various concentrations of isoprenaline (0.01-10 mumol/liter) for 30 min at a constant flow rate (6.5 ml/min) at 37-44 degrees C. The occurrence of ventricular fibrillations was isoprenaline concentration dependent and also perfusion temperature dependent in the combined treatment with various concentrations of isoprenaline and high perfusion temperatures. When the hearts were perfused with isoprenaline (1 mumol/liter) in the presence of tropolone (100 mumol/liter) at 40-41 degrees C, the duration of ventricular fibrillations was significantly prolonged, but the incidence of ventricular fibrillations was similar to that produced with isoprenaline (1 mumol/liter) alone. The antiarrhythmic drugs such as quinidine sulfate, lidocaine hydrochloride, dl-propranolol hydrochloride, carteolol hydrochloride, atenolol, dl-verapamil hydrochloride, and diltiazem hydrochloride, given at a concentration of 10 mumol/liter, significantly suppressed the incidence and duration of such ventricular fibrillations. Bretylium tosylate (10 mumol/liter) significantly suppressed the duration of the ventricular fibrillations but not their incidence. These results indicate that ventricular fibrillation induced by combined treatment with a high concentration of isoprenaline and tropolone at a high perfusion temperature in isolated rat hearts is a more useful experimental model of arrhythmia than conventional models.

Dual-wavelength He-Ne laser running at 7.70 and 3.39 microm

Two mid-infrared laser transitions in a He-Ne discharge have been investigated. They form part of a cascade transition and therefore have a power dependence, which has been examined and shown to satisfy the relationship P(7.70) = 410 + 0.63 x P(3.39), where P(7.70) and P(3.39) are the powers of the 7.70- and 3.3 9-microm lines, respectively, in micro-watts.