Response and level of beta-adrenergic, vasoactive intestinal peptide, and PACAP receptors during the circadian cycle.

PURPOSE: To determine whether a nocturnal increase of ciliary process beta-adrenergic receptor responsiveness can explain the observation that timolol decreased the aqueous flow rate and intraocular pressure (IOP) during the night but not during the day in rabbits. METHODS: Rabbits were housed in alternating 12-hour periods of light and dark. In vitro stimulation of tissue cyclic adenosine monophosphate (cAMP) levels by isoproterenol (ISO), vasoactive intestinal peptide (VIP), pituitary adenylate cyclase activating polypeptide (PACAP), or a soluble derivative of forskolin (sFSK) was measured in ciliary processes harvested at mid-light phase and early and late dark phase. Inhibition of ISO and VIP stimulation of ciliary process cAMP by an alpha 2-adrenergic agonist and maximal binding of [125I]I-pindolol, [125I]I-VIP, and [125I]I-PACAP in ciliary process membranes were measured at the same three times. RESULTS: Although there may have been a nocturnal increase in the sensitivity of ciliary process cAMP levels to stimulation by ISO, this was not observed consistently, VIP, but not PACAP, stimulation increased at night, but there was no change in the response to sFSK. Inhibition by apraclonidine of elevated ciliary process cAMP levels was constant at all three times. Ligand-binding studies showed little change in ciliary process beta-adrenergic, VIP-, or PACAP-receptor levels at the three times. CONCLUSIONS: There is no convincing evidence for a nocturnal increase in beta-adrenergic receptor sensitivity in rabbit ciliary processes that could explain the difference between day and night effects of timolol on aqueous flow and IOP.

Absence of mutagenic action of 5 beta-cholan-24-oic acid derivatives in the bacterial fluctuation and standard Ames tests.

Published data on the mutagenicity of 3 bile acids in the bacterial fluctuation test are conflicting. Eleven 5 beta-cholanoic acids including 2 of the bile acids were assayed for mutagenicity in Salmonella typhimurium TA98 and TA100 in the fluctuation tests. In any of these bile acids at the doses tested, there were no dose-related statistically significant increases in mutagenicity compared with appropriate controls. Similarly, none of these compounds showed positive mutagenicity in both strains in the standard Ames test either with or without hepatic metabolic activation. Our results support the claim that 3 bile acids are not mutagenic, and indicate that the initiation activity of 5 beta-cholanoic acids is not demonstrable with a short-term assay using Salmonella strains.

Circadian change of adenylate cyclase activity in rabbit ciliary processes.

PURPOSE: To characterize in vivo changes of adenylate cyclase activity in rabbit ciliary processes during the circadian cycle. METHODS: After removal of vitreous, lens, retina and choroid from freshly enucleated rabbit eyes, the anterior segment and attached sclera was chilled in cold buffer containing the non-selective phosphodiesterase (PDE) inhibitor, 3-isobutyl-1-methylxanthine (IBMX). Then ciliary processes were excised and homogenized in ice cold trichloro-acetic acid (TCA) 2.5 min after IBMX treatment. Increased cyclic AMP in response to PDE inhibition was measured in ciliary processes at six times during the circadian cycle, after preganglionic section of the cervical sympathetic trunk (decentralization, DX), and after topical instillation of hydroxyamphetamine, timolol, brimonidine, rauwolscine or a soluble derivative of forskolin. RESULTS: The increase of rabbit ciliary process cyclic AMP levels in response to PDE inhibition with IBMX was enhanced at night. Much of the enhanced nocturnal increase persisted in constant dark and was blunted by DX. Topical instillation of hydroxyamphetamine enhanced the increase during the day; whereas, timolol, a beta-adrenergic antagonist, or brimonidine, an alpha2-adrenergic agonist, blunted the IBMX induced increase. Neither instillation of rauwolscine, an alpha2-adrenergic antagonist, nor the soluble forskolin derivative enhanced the increase of cyclic AMP after IBMX. CONCLUSIONS: The technique reported here can be used to estimate ciliary process adenylate cyclase activity in vivo. There is a circadian rhythm of adenylate cyclase activity in rabbit ciliary processes that is driven in part by ocular sympathetic input and stimulation of beta-adrenergic receptors.

Ophthalmic diseases in bedridden patients with severe dementia.

Ophthalmologic examinations were performed on the 176 eyes of 88 bedridden patients with severe dementia. There were some pathologic changes in the external and anterior segments of 93 eyes. We observed infectious external and anterior segment eye diseases in 80 of these 93 eyes (86.0%). Fundus diseases were found in 34 eyes, but treatment was not necessary. Infectious eye diseases appeared to be the most prevalent ocular problem in these patients. Cultures of conjunctival swabs commonly demonstrated Staphylococcus aureus. No differences were noted in tear secretion rate or lysozyme concentrations in tears between eyes with and without infection. The blinking frequency was significantly reduced in infected eyes compared to normal eyes. Failure of the lacrimal drainage system was observed more often in infected eyes than in normal eyes. This study demonstrated that bedridden patients with severe dementia develop infectious eye diseases easily, to which stasis of tear flow seems to predispose. In caring for bedridden patients with severe dementia, ophthalmologists must be concerned with controlling infectious eye diseases.

Ca2+/calmodulin effects on cAMP response in cultured chick ciliary epithelial cells.

The authors investigated the influence of the elevation of intracellular Ca2+ concentration on the production of cyclic adenosine 3',5'-monophosphate (cAMP) using cultured chick embryo ciliary epithelium (CE). We examined the effects of calcium ionophore (A23187) on cAMP production after incubation with vasoactive intestinal peptide (VIP), isoproterenol (ISO), sodium fluoride (NaF) or forskolin (FSK). A23187 had no effect on the basal cAMP level, or the NaF- and FSK-stimulated responses for cAMP level; but A23187 potentiated VIP- and ISO-stimulated cAMP responses. Calmodulin antagonist (W-7) was very effective in inhibiting the potentiating effects of A23187 on VIP and ISO-stimulated production of cAMP. Our present findings suggested that Ca2+/calmodulin may potentiate the receptor-mediated cAMP pathway through Ca2+/calmodulin-dependent protein kinase in the CE.

[Calcium ion effects on cAMP system in cultured chick ciliary epithelial cells].

I investigated stimulation of cyclic adenosine 3': 5'-monophosphate (cAMP) production by vasoactive intestinal peptide (VIP), isoproterenol (ISO), sodium fluoride (NaF), and forskolin (FSK) in cultured chick embryo ciliary epithelium (CE). In order to clarify the influence of intracellular calcium ions on cAMP production when CE was activated by cAMP activating agents, I also studied the effects of calcium ionophore (A23187) on VIP, ISO NaF, and FSK stimulated cAMP production. After stimulation with VIP, ISO, NaF, and FSK, a concentration dependent increase in cAMP level was observed. Addition of A23187 activated VIP and ISO stimulated cAMP production. However, A23187 had no effect on the cAMP level when CE was stimulated by NaF and FSK. The activating effect of A23187 was inhibited by calcium/calmodulin-dependent protein kinase inhibitor (W-7). I speculate that calcium ions have different effects on receptor-mediated cAMP pathway and non-receptor-mediated cAMP pathway, and that calcium ions modulate the cAMP pathway through the calcium/calmodulin-dependent protein kinase.

Clinical outcomes of the placement of a drug-eluting stent with the use of Rotablator™ in dialytic patients: in comparison with non-dialytic patients.

Much remains unknown about the clinical outcomes of drug-eluting stent (DES) implantations following ablation by the Rotablator™ in dialytic patients. The purpose of this study was to examine these outcomes. Of the 43 patients who underwent elective DES implantation following ablation with the Rotablator™-17 lesions on 12 dialytic patients were designated to Group H and 54 lesions on 31 non-dialytic patients were designated to Group N. QCA data, the rate of restenosis and the avoidance rate of cardiac events at the chronic phase (920 ± 446 days) were studied. The age of patients in Group N was significantly older (60 ± 8 years old in Group H vs. 73 ± 7 in Group N, p < 0.05). The rate of DM complication was significantly higher in Group H (75.0% in Group H vs. 32.0% in Group N, p < 0.05). The late loss was 1.18 ± 0.97 mm in Group H and 0.38 ± 0.53 mm in Group N, or significantly greater in Group H (p < 0.05). The restenosis rate was also higher in group H. (42.9% in Group H and 6.0% in Group N). The avoidance rate of cardiac events at the chronic phase was significantly lower in Group H. The study suggested that in patients who received DES with the use of the Rotablator™, clinical outcomes were poorer in dialytic patients than in non-dialytic patients.

Fabrication of Mo/Al multilayer films for a wavelength of 18.5 nm.

This paper reports the fabrication and evaluation of Mo/Al and Mo/Si multilayer films (MLs) for a wavelength of 18.5 nm. Calculated reflectivities of Mo/Al MLs at an incident angle of 10 degrees were about 7% higher than those of Mo/Si MLs. MLs were fabricated using an RF-magnetron sputtering deposition system. The measured reflectivity of Mo/Al MLs was 33.5%. The cause of the decreasing reflectivity was supposed to be the surface and interfacial roughness. In the surface observation utilizing atomic force microscopy, the surface roughness of Mo/Al MLs was dominated by the Al layer. Therefore, the conditions for fabricating Al films were optimized.

Vitamin B-6-supplemented diets compared with a low vitamin B-6 diet suppress azoxymethane-induced colon tumorigenesis in mice by reducing cell proliferation.

Male ICR mice were examined for the effect of vitamin B-6 [pyridoxine (PN) HCl] on azoxymethane-induced colon tumorigenesis. Mice were fed the diets containing 1, 7, 14 or 35 mg PN HCl/kg for 22 wk, and given a weekly injection of azoxymethane (5 mg/kg body) for the initial 10 wk. Compared with the 1 mg PN HCl/kg diet, 7, 14 and 35 mg PN HCl/kg diets significantly suppressed the incidence and number of colon tumors, colon cell proliferation and expressions of c-myc and c-fos proteins. For some variables, 14 and 35 mg PN HCl/kg diets were more effective than the 7 mg/kg diet. Supplemental vitamin B-6 had no influence on the number of colon apoptotic cells. The results suggest that elevating dietary vitamin B-6 suppresses colon tumorigenesis by reducing cell proliferation.

Effects of lidocaine and quinidine on post-repolarization refractoriness after the basic and premature action potentials: consideration of aim of antiarrhythmic drug therapy.

Antiarrhythmic drugs are often more effective in suppressing ventricular tachycardias than are background premature extrasystoles. The mechanism of action of these agents was examined by studies on the effects of lidocaine and quinidine on post-repolarization refractoriness of both basic and premature action potentials. In the absence of antiarrhythmic drugs, the excitability threshold was relatively constant after the end of repolarization of both basic and premature action potentials. In the presence of lidocaine or quinidine, the strength-interval curves were shifted to the right and superiorly, and the two drugs had different effects on the course of the strength-interval curve and Vmax recovery, presumably due to use-dependent V max block. Moreover, depressions of Vmax and excitability were more marked after the premature action potential than after the basic action potential. These results suggest that lidocaine and quinidine cause more depression of the excitability of second premature contractions than of first premature contractions, and also indicate that for protection against sustained ventricular tachycardias, it may not be necessary to suppress chronic premature ventricular contractions.

Carcinogenic activity of endogenously synthesized N-nitrosobis(2-hydroxypropyl)amine in rats.

The carcinogenic activity of endogenously synthesized N-nitroso-bis(2-hydroxy-propyl)amine (NDHPA) was investigated in male Wistar rats administered bis(2-hydroxypropyl)amine (DHPA), mixed into a powdered diet at a concentration of 1%, and NaNO2 dissolved in distilled water at concentrations of 0.15% and 0.3%, for 94 weeks. Urinary excretion of NDHPA clearly demonstrated its endogenous synthesis in rats given 1% DHPA and 0.3% NaNO2, but not in the groups receiving either of these precursors alone. Tumours of the nasal cavity, lung, oesophagus, liver and urinary bladder were found in rats treated with 1% DHPA and 0.15% or 0.3% NaNO2. The incidences of nasal cavity and lung tumours reached 74% and 58% respectively, in rats given 1% DHPA and 0.3% NaNO2. The tumour distribution was almost the same as that seen in rats given NDHPA. These results indicate that endogenously synthesized NDHPA has similar carcinogenic activity to exogenously administered NDHPA in rats.

Isomagnetic maps in right ventricular overloading.

Isomagnetic maps were recorded in normal subjects and in patients with systolic overloading of the right ventricle. The isomagnetic maps examined in this study indicated the instantaneous current source of the heart by applying the "corkscrew rule." The magnetic field recorded by a second derivative gradiometer detected clearly the cardiac current source from the right ventricle, which is located close to the anterior chest wall, and improved diagnostic sensitivity. Moreover, the isomagnetic map showed multiple dipoles, which are difficult to detect in the electrocardiogram or isopotential map. These results suggest that the magnetocardiogram provides useful information on current sources to supplement information obtained by the conventional electrocardiogram.

Experimental studies on death by fire in automobiles and exhaust gas poisoning.

Studies were made on the acid-base balance, blood gases, and carbon monoxide (CO), cyanide, and sulfur dioxide concentrations in the blood of albino rabbits that died from automobile exhaust gas poisoning (group I) or fires in cars (complete combustion, group II; incomplete combustion, group III). In group I, the temperature and CO concentration increased gradually to 35 degrees C and 5.2% in 70 min. The animals died after 9 min, when the values were 20 degrees C and 5.2%, respectively. In group II the animals died after 9 min, when the values were 55 degrees C and 1.95%, respectively. In group III, the temperature was very high (870 degrees C), but the CO concentration was not (0.6-1.3%) after 4 min. The animals died after 5 min. In all experimental groups, marked acidosis and hypoxemia were seen, but the CO2 tension (PCO2) was high, in contrast to previous studies on pure CO poisoning. In group I, the level of carboxyhemoglobin (CO-Hb) was significantly higher (91.2 +/- 3.4% in arterial blood, 87.5 +/- 8.1% in venous blood; p less than 0.01) than in groups II and III. Although the O2 tensions of venous and arterial blood (PvO2, PaO2) were very low, that of arterial blood was higher, suggesting that O2 was still being utilized in the tissues at the time of death. In group II, CO-Hb was high (57.7 +/- 16.0% in arterial blood, 61.2 +/- 20.6% in venous blood) and the acid-base balance indicated marked acidosis. In group III, the CO-Hb, PCO2 and cyanide levels in the blood were very high.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinogenic activity of endogenously synthesized N-nitrosobis(2-hydroxypropyl)amine in rats administered bis(2-hydroxypropyl)amine and sodium nitrite.

The carcinogenic activity of endogenously synthesized N-nitrosobis(2-hydroxypropyl)amine (BHP) was investigated in male Wistar rats administered bis(2-hydroxypropyl)amine (BHPA) mixed in powder diet at a concentration of 1%, and sodium nitrite (SN) dissolved in distilled water at concentrations of 0.15 and 0.3%, for 94 weeks. Urinary excretion of BHP was detected in rats given 1% BHPA and 0.3% SN but not in the groups receiving either of these precursors alone. Nasal cavity, lung, esophagus, liver and urinary bladder tumors were found in animals treated with combinations of 1% BHPA and 0.15 or 0.3% SN, suggesting that the target organs of the endogenously synthesized BHP are similar to those affected when the carcinogen is administered exogenously. The incidences of nasal cavity and lung tumors reached 74 and 58% in rats given 1% BHPA and 0.3% SN, respectively. Tumors at sites other than target organs were only found at levels similar to those previously reported for spontaneous tumors in male Wistars. The present results clearly indicated the tumor inducibility of a nitrosatable amine, BHA, through an endogenous nitrosation by feeding to rats in conjunction with nitrite, and provide further suggestive evidence that endogenous nitrosations of environmental nitrosatable amines can be a potential risk factor in human cancer development.