The effect of L-arginine on intraocular pressure in the human eye.

PURPOSE: L-Arginine, a non-toxic amino acid, is converted to nitric oxide (NO) by NO synthase. Recent findings have demonstrated that NO serves as an ocular hypotensive agent. The objectives of the present study were to clarify the effect of L-arginine on intraocular pressure (IOP), pupil size, refraction and accommodative amplitude in human eyes, and to examine whether L-arginine is converted to NO in vivo. METHODS: Fourteen volunteers received an intravenous drip-infusion of 100 ml of L-arginine (10.0 g) solution. IOP levels were measured before, during and after infusion using Goldmann applanation tonometry. Pupillary diameter, refraction and accommodative amplitude were also measured in human subjects. In rabbits, the nitrite levels in the aqueous humor were measured during L- or D-arginine infusion. RESULTS: The mean IOP of the L-arginine group was significantly decreased during infusion, but recovered rapidly after infusion. The mean IOP of the control group increased during infusion. The changes in pupillary diameter, refraction, and accommodative amplitude before and after infusion of L-arginine were not significant. L-Arginine significantly elevated the level of nitrite in the aqueous humor compared with the controls. CONCLUSIONS: These findings demonstrated that L-arginine lowers IOP mainly through the formation of NO.

Different responsiveness to nitric oxide-cyclic guanosine monophosphate pathway in cholinergic and tachykinergic contractions of the rabbit iris sphincter muscle.

PURPOSE: In the rabbit iris sphincter muscle, sodium nitroprusside (SNP), a nitric oxide (NO) donor, inhibits cholinergic contraction but does not affect tachykinergic contraction in vitro. The objectives of the current study were to clarify the mechanism for the different responsiveness to NO in cholinergic and tachykinergic muscular contractions, and to examine whether the mechanism for NO-induced inhibition of cholinergic muscular contraction is operative in vivo. METHODS: Iris sphincter muscle was dissected from the rabbit eye pretreated with or without endotoxin (lipopolysaccharide, LPS) in vivo. Cyclic guanosine monophosphate (cGMP) content in the iris sphincter muscle was determined by radioimmunoassay. The motor activity of the ring-shaped iris sphincter muscle was measured isometrically. Sodium nitroprusside, carboxy-2-phenyl-4,4,5,5,-tetramethyl-imidazoline-1-oxyl-3-oxide (C-PTIO, a scavenger of NO radicals), and 8-bromo cGMP (a permeable cGMP analogue) were administered between the first and second administrations of carbachol and neurokinin A, both of which had caused sustained contraction in the iris sphincter muscle. RESULTS: Sodium nitroprusside inhibited the contraction of the iris sphincter muscle caused by carbachol but had no effect on the contraction caused by neurokinin A. Application of C-PTIO significantly reduced SNP-induced cGMP accumulation in the muscle, as well as the SNP-induced inhibition of muscular contraction caused by carbachol. Neither carbachol nor neurokinin A influenced SNP-induced cGMP accumulation in the muscle. Induction of 8-bromo-cGMP significantly diminished the muscular contraction caused by carbachol but not that caused by neurokinin A. In vivo pretreatment of the eye with LPS increased, in a time-dependent manner, the cGMP accumulation in the iris sphincter muscle, which was significantly inhibited by pretreatment of NG-nitro-L-arginine methyl ester (an inhibitor of NO synthesis) in vivo. CONCLUSIONS: These results demonstrate that in rabbits the increase in cGMP accumulation induced by NO in the iris sphincter muscle is involved in the cholinergic contraction but not in the tachykinergic contraction, suggesting that different sensitivities to cGMP are essential for the different responsiveness to NO. Furthermore, the results of this study showed that the NO-cGMP pathway is operative in vivo and regulates iris sphincter muscle tone, at least when the eyes are infected with bacteria.

Nitric oxide-sensitive and -insensitive contractions of the isolated rabbit iris sphincter muscle.

PURPOSE: The rabbit iris sphincter muscle is innervated by cholinergic and tachykinergic nerves that regulate its tone. To clarify the involvement of nitric oxide (NO) in the postsynaptic regulation of the rabbit iris sphincter muscle tone, the authors examined the effects of NO-related agents on the cholinergic contraction induced by carbamylcholine (carbachol) and the tachykinergic contraction induced by neurokinin A. METHODS: The motor activity of the ring-shaped rabbit iris sphincter muscle was measured isometrically. Sodium nitroprusside (SNP, a NO donor) was administered between the first and second administrations of carbachol and neurokinin A, each of which induced sustained contraction. The effects of carboxy-2-phenyl-4,4,5,5,-tetramethyl-imidazoline-l-oxyl-3-oxide (carboxy-PTIO, a scavenger of NO radicals), NG-monomethyl-L-arginine (L-NAME, an inhibitor of NO formation from L-arginine), and methylene blue (an inhibitor of soluble guanylate cyclase) on contractions induced by carbachol and neurokinin A also were studied. Cyclic guanosine monophosphate (GMP) content in the muscle was determined by radioimmunoassay. RESULTS: Sodium nitroprusside inhibited carbachol-induced contractions of the iris sphincter muscle in a concentration-dependent manner but had no effect on neurokinin A-induced muscle contractions. Carboxy-PTIO and methylene blue significantly diminished the inhibitory effect of SNP on carbachol-induced contractions. L-NAME had no effect on contractions induced by either carbachol or neurokinin A. Sodium nitroprusside alone increased cyclic GMP accumulation in a concentration-dependent manner. CONCLUSIONS: This study showed that SNP inhibited cholinergic contractions mainly through a cyclic GMP-dependent mechanism but did not affect the tachykinergic contractions, indicating that cholinergic contraction is NO sensitive, whereas tachykinergic contraction is NO insensitive. These findings suggest that in rabbits, the cholinergic and tachykinergic responses have distinct features for the fine adjustment of the iris sphincter muscle tone.

Retinal complications during interferon therapy for chronic hepatitis C.

OBJECTIVES: Various side effects of interferon (IFN) therapy have been reported. In this study, we examined retinal change during IFN therapy. METHODS: We performed ophthalmological examinations before, during, and after therapy on 63 patients with chronic hepatitis C who were receiving either natural IFA-alpha or recombinant IFN-alpha 2a or 2b. RESULTS: No retinal lesion was detected before IFN therapy, but, during therapy, retinal abnormality or retinopathy developed in 36 (57.1%) of 63 patients, including retinal hemorrhage in 25 patients and cotton-wool spots in 28 patients. They were noted early in the course of IFN therapy, within the first 4 wk in 67% (24/36) and within 8 wk in 86% (31/36). The incidence was not influenced by the type of IFN but was higher among diabetic (11/12, 92%, p < 0.05) or hypertensive patients (4/5, 80%, not significant) than among patients without either diabetes or hypertension (24/49, 49%). There was no relation between the incidence of retinopathy and the level of ALT activity or white blood cell or platelet counts. However, retinopathy occurred in most patients receiving IFN therapy after white blood cell count and platelet count reached a nadir. The levels of LDL-cholesterol and the atherosclerotic index in patients with retinopathy were slightly higher than those in the patients without retinopathy. CONCLUSIONS: These results suggest that retinopathy often occurs in patients with chronic hepatitis C who are receiving IFN and that we should closely monitor patients for retinal complications during IFN therapy.

[Interferon-induced retinal changes].

Fifty patients treated with interferon for chronic type C hepatitis, chronic type B hepatitis and renal cell carcinoma were examined for retinal complications. Retinal hemorrhages or cotton wool spots were observed in 23 (46%) of the patients. Retinal hemorrhages without cotton wool spots were found in 14 patients, cotton wool spots without retinal hemorrhages in 5 patients, and both hemorrhages and cotton wool spots in four patients. These findings were potentially reversible. There was one case of branch retinal artery occlusion and one case with microaneurysm. Red blood cell count decreased significantly in the patients with retinopathy compared with those without retinopathy (p < 0.05%). Patients with diabetes, hypertension, retinal arterial sclerosis, and anemia were at risk for retinopathy.

A structural study of calcium-binding equine lysozyme by two-dimensional 1H-NMR.

Since 1H-NMR spectra of the calcium bound form (holo) and the calcium free form (apo) of equine lysozyme have an overall similarity, the folded structure of apo equine lysozyme seems to be similar to the holo structure at 25 degrees C and pH 7.0, even at low ionic strengths except for subtle conformational change. However, calcium titration experiments showed that a number of resonances change by a slow exchange process. The changes saturated at one calcium ion per one lysozyme molecule, and no more change was observed by further addition of calcium ions. This shows that just one calcium ion binds to equine lysozyme. To make assignments for these changed proton resonances, two-dimensional 1H-NMR studies, correlated spectroscopy (COSY), two-dimensional homonuclear Hartmann-Hahn spectroscopy (HOHAHA) and nuclear Overhauser effect spectroscopy (NOESY) were carried out. A structural model of equine lysozyme based on the crystal structure of human lysozyme was estimated and used to assign some resonances in the aromatic and beta-sheet regions. It was possible to use some proton signals as a probe to determine the specific conformational change induced by calcium ions. The calcium binding constant KCa was estimated from calcium titration experiments in which changes in the proton signal were monitored. The log KCa value was found to be on the order of 6-7, which is in agreement with the calcium binding constant determined by fluorescence probes. This means that the protons are affected by specific calcium binding.

Behavioral and electroantennogram responses of periplanone analogs.

The biological activities of synthetic periplanone analogs, including four candidates of periplanone-A (P-A), were evaluated by behavioral and electroantennogram (EAG) assays. Among 16 periplanone analogs, six compounds evoked pheromonal activity from the male American cockroaches. The threshold dosages of these biological active analogs were 10-10(5) times lower than that of the known periplanone mimic, germacrene-D. The conformation required for eliciting the pheromonal activity is discussed in terms of the structure-activity relationship of these analogs. Hauptmann's P-A elicited the strongest pheromonal activity among four candidates of P-A in our bioassay, suggesting that Hauptmann's P-A is a natural P-A produced from female cockroaches.

Conformational analyses of periplanone analogs by molecular mechanics calculations.

Conformational parameters of pheromonally active analogs (1 and 2) of periplanones, the sex pheromones of the American cockroach, were investigated by molecular mechanics calculations. They existed in several conformers with small energy differences. These results were supported by NMR analysis. The structural features of the conformers of the analogs were compared with X-ray structures of periplanones.

Conformational analysis of serricornin: Application of molecular mechanics calculations to stereochemical assignment of serricornin, sex pheromone of cigarette beetle (Lasioderma serricorne F.).

Conformational analysis using molecular mechanics (MM) was performed for a determination of the stereochemistry of serricornin, the sex pheromone of the cigarette beetle (Lasioderma serricorne F.). An exhaustive conformational analysis using MM2 calculations with algorithms for covering torsional energy surfaces of flexible molecules furnishes coordinates and steric energies of all local energy minimum conformers of serricornin, both acyclic and the corresponding cyclic forms. These coordinates gave angles required for the calculation of vicinal H/H coupling constants ((3) J HHs) of each energy minima by Altona's modified Karplus equation. The Boltzmann distributions of all local energy minima were calculated from their steric energies to furnish populations of each energy minimum conformer. Populationweighted averaged(3) J HHs of four enantiomeric pairs, (S (*),S (*),S (*))-, (S (*),S (*),R (*))-, (S (*),R (*),S (*))-, and (R (*),S (*),S (*))-serricornins were calculated from the data above. The observed(3) J HHs of the naturally occurring serricornin, both acyclic and cyclic forms, are fitted best to calcd.(3) J HHs of (4S (*), 6S (*), 7S (*))-acyclic and (3S (*), 5S (*), 6S (*))-cyclic serricornin, respectively, among those of four enantiomeric pairs of serricornin.

Female-produced oviposition deterrents of the cigarette beetle,Lasioderma serricorne (F.) (Coleoptera: Anobiidae).

Oviposition deterrents of the cigarette beetle,Lasioderma serricorne, were isolated from its adult body extract and found to be identical to (2S,3R,1'S)-2,3-dihydro-3,5-dimethyl-2-ethyl-6-(l'-methyl-2'-oxobutyl)-4H-pyran-4-one (α-serricorone) and its l'R-epimer (ß-serricorone) by spectroscopic evidence. Serricorone was previously found as one of the minor sex pheromone components of the same insect, and hence indicating bi-functional nature. The presence of two isomers in the body was proved by careful treatment. Each of them exhibited the same level of oviposition deterring activity, which was less potent than the crude body extract at an increased concentration.

Behavioral responses of malePeriplaneta americana L. to female sex pheromone components, periplanone-A and periplanone-B.

Bioassays were performed on malePeriplaneta americana L. using synthetic (-)-periplanone-B (P-B) and Hauptmann's (-)-periplanone-A (P-A), and their mixtures at various ratios to estimate the roles of both periplanones for the sexual communication of the species. Both P-A and P-B elicited qualitatively the same responses, such as antennal movement, rapid locomotion, wing raising, and homosexual behavior of male cockroaches, but the threshold of the pheromone activities for P-B was two orders of magnitude lower than that of P-A. Neither synergistic nor inhibitory but only a simple integrated effect on the responses was observed when mixtures of P-A and P-B were applied.

Identification of female-produced sex pheromone from banded cucumber beetle,Diabrotica balteata leconte (Coleoptera: Chrysomelidae).

A sex pheromone produced by female banded cucumber beetle adults,Diabrotica balteata LeConte, was isolated from volatiles trapped on Porapak Q and identified as 6,12-dimethylpentadecan-2-one. The structure was elucidated by spectroscopic analyses and confirmed by synthesis. The synthesized racemic compound was equal to the purified natural pheromone in eliciting responses by banded cucumber beetle males to field traps. A doseresponse characteristic was demonstrated for the racemic material formulated on filter paper or rubber septa and placed in field traps. The absolute configuration at the C-6 and C-12 positions was not established.

Isolation, identification, and synthesis of male-produced sex pheromone of papaya fruit fly,Toxotrypana curvicauda Gerstaecker (Diptera: Tephritidae).

A male-produced sex pheromone of the papaya fruit fly,Toxotrypana curvicauda Gerstaecker, was isolated from volatiles collected from air passed over calling males and was identified as 2-methyl-6-vinylpyrazine by comparative gas-liquid chromatographic and spectroscopic evidence. Synthetic 2-methyl-6-vinylpyrazine elicited typical pheromonal responses from unmated mature female flies such as walking, running, and flying in an arena bioassay; flying upwind with a zigzag flight pattern; and hovering in the pheromone plume in a wind-tunnel bioassay. These responses were similar quantitatively and qualitatively to responses to naturally occurring pheromone from calling male papaya fruit flies.

Inhibitory action of (4S,6S,7R)-isomer to pheromonal activity of serricornin, (4S,6S,7S)-7-Hydroxy-4,6-dimethyl-3-nonanone.

By adding the effects of a series of the stereoisomers to the pheromonal activity of serricornin, (4S,6S,7S)-7-hydroxy-4,6-dimethyl-3-nonanone, the sex pheromone of the cigarette beetleLasioderma serricorne (F.) was investigated. The experiments using synthetic enantiomeric mixtures and optically active stereoisomers showed that the (4S,6S,7R)-isomer inhibited significantly the pheromonal activity of serricornin.

Reinvestigation of anhydroserricornin, (2S,3S)-2,6-diethyl-3,5-dimethyl-3,4-dihydro-2H-pyran, as a sex pheromone component for male cigarette beetle.

Reinvestigation of the pheromonal activity of anhydroserricornin, (2S,3S)-2,6-diethyl-3,5-dimethyl-3,4-dihydro-2H-pyran, showed that the magnitude of its activity was less than 1/10(3) of that of serricornin, 7-hydroxy-4,6-dimethyl-3-nonanone, the sex pheromone of the cigarette beetleLasioderma serricorne (F.). Neither a synergistic nor an inhibitory effect of anhydroserricornin addition on the action of serricornin was observed.

Lasioderma chemistry sex pheromone of cigarette beetle (Lasioderma serricorne F.).

A chemical study of the sex pheromone of the cigarette beetle was carried out. Seven components were isolated from active fractions of column chromatography of the female extract, and their structures were elucidated by spectroscopic evidence and confirmed by synthesis to be (4S,6S,7S)-4,6-di-methyl-7-hydroxynonan-3-one (serricornin) (I), 2,6-diethyl-3,5-dimethyl-3,4-dihydro-2H-pyran (anhydroserricornin) (II), 4,6-dimethylnonan-3,7-dione (III), 4,6-dimethylnonan-3,7-diol (IV), 4,6-dimethyl-7-hydroxy-4-nonen-3-one (V), (2S,3R)-2,3-dihydro-3,5-dimethyl-2-ethyl-6-(l-methyl-2-oxobutyl)-4H-pyran-4-one (serricorone) (VI) and (2S,3R)-2,3-dihydro-3,5-dimethyl-2-ethyl-6-(1-methyl-2-hydroxybutyl)-4H-pyran-4-one (serricorole) (VII).These structural features suggested that the occurrence of these components might be related to the polyketide biosynthesis. The behavioral bioassay and BAG experiments revealed the biological role of each component in the copulatory behavior of this insect.