Nitric oxide and vasodilation in human limbs

Joyner, Michael J., and Niki M. Dietz.Nitric oxide and vasodilation in human limbs. J. Appl. Physiol. 83(6): 1785-1796, 1997.Both theskeletal muscle and skin of humans possess remarkable abilities tovasodilate. Marked vasodilation can be seen in these vascular beds inresponse to a variety of common physiological stimuli. These stimuliinclude reactive hyperemia (skin and muscle), exercise hyperemia(muscle), mental stress (muscle), and whole body heating (skin). Thephysiological mechanisms that cause vasodilation in response to thesestimuli are poorly understood, and the substance(s) responsible for itremain unclear. In this context, recent attention has been focused onthe possible contribution of nitric oxide (NO) to the regulation ofhyperemic responses in human skin and skeletal muscle. The emergingpicture is that NO is not an essential component of the dilatorresponse seen during reactive hyperemia. However, it does appear thatNO may play a modest role in exercise hyperemia. NO appears to play amajor role in the skeletal muscle vasodilation seen in response tomental stress in humans. Preliminary evidence also indicates that NO isnot essential for the normal dilator responses observed in thecutaneous circulation during body heating in humans, but this issueneeds further study. There are a number of possible mechanisms thatmight mediate NO release in humans, and the role of these mechanisms inthe various hyperemic responses is also poorly understood. The role ofaltered NO-mediated vasodilation in some disease states is alsodiscussed. Whereas NO is a potent vasodilating substance, the actionsof NO alone do not explain a variety of poorly understood vasodilatormechanisms in conscious humans. Much work remains for those interestedin the role of NO in the regulation of blood flow to the skin and skeletal muscle of humans.

     

Vibrio trachuri Sp. Nov., a New Species Isolated from Diseased Japanese Horse Mackerel

A new species, Vibrio trachuri sp. nov., was isolated from the cultured Japanese horse mackerel (Trachurus japonicus). These Vibrio were Gram negative, motile rods and formed yellow colonies on BTB teepol and TCBS plate, turned TSI medium to yellow and was sensitive to 150 μM O/129 (2,4-diamino-6,7-diisopropyl pteridine phosphate) like Listonella anguillarum which has been described as Vibrio anguillarum. However, the results of VP test and decarboxylation of lysine or dihydrolation of arginine suggested that these Vibrio are rather closely related to V. parahaemolyticus. DNA similarity determined by the microplate hybridization technique revealed that these Vibrio are genetically quite distant from Listonella anguillarum or V. parahaemolyticus and rather close to V. harveyi, although there was no Vibrio species which had more than 70% similarity value. From these results we propose to nominate Vibrio trachuri sp. nov. for this new Vibrio species.     

The lateral diffusion coefficient of lecithin molecules in single bilayer vesicles studied by 14N NMR

The ¹⁴N nuclear relaxation times T₁ and T₂ in egg yolk phosphatidylcholine have been observed in single bilayer vesicles dispersed in the media of different viscosities, ¹H₂O and ²H₂O. The lateral diffusion coefficient of lipid molecule D has been calculated according to the method reported earlier: D = 2.2 × 10^?8cm²s^?1 in ¹H₂O and 2.1 × 10^?8cm²s^?1 in ²H₂O at 20°C. They are in excellent agreement. This result gives a strong basis of usefulness of ¹⁴N NMR method in the evaluation of D without introducing any system perturbation.     

Chloride attachment negative-ion mass spectra of sugars by combined liquid chromatography and atmospheric pressure chemical ionization mass spectrometry

A method has been developed for the rapid determination of sugars, including molecular weight measurements, using high-performance liquid chromatography coupled with negative-ion, atmospheric-pressure chemical-ionization mass spectrometry. The chromatography was carried out on a 250 × 4 mm I.D. column packed with 7 μm NH₂-silica. The mobile phase consisted of a high percentage of methanol or acetonitrile with a small amount of chloroform. During the mass spectrometry, a strong base is formed from the polar solvent molecules by corona discharge, followed by ion—molecule reactions in the chemical ionization ion source (e.g. the methoxy anion is formed from methanol). This strong base reacts with the chloroform, generating chloride ions, which in turn react with the neutral sugar molecules as they elute from the chromatograph. The chloride ion and sugar interactions yield chloride-attachment ions, which are further stabilized by successive collisions. In this method, authentic monosaccharides and some oligosaccharides show dominant quasi-molecular ions, [M + Cl]⁻, with little fragmentation, and it is particularly useful for the molecular weight determination of sugars.     

Free radical damage to proteins: the influence of the relative localization of radical generation, antioxidants, and target proteins

Free radicals were generated at known rates in the aqueous phase (by means of 2,2'-azobis (2-amidinopropane) dihydrochloride [AAPH]) and in a membranous (lipid) phase (by means of 2,2'-azobis (2,4-dimethylvaleronitrile [AMVN]). A soluble protein (bovine serum albumin: BSA), and membranes of lysed mitochondria containing radioactively labeled monoamine oxidase (MAO), were exposed to the resultant radical fluxes. Antioxidants were added to the system, either in the aqueous phase (Trolox) or in a liposomal membrane phase (alpha-tocopherol). Protein damage was assessed as tryptophan oxidation and conformational changes in tryptophan fluorescence of the soluble protein, BSA, and as fragmentation of both BSA and monoamine oxidase. Radicals generated in the aqueous phase, by AAPH, were effective in damaging BSA and MAO. Radicals generated within the liposome membrane phase (by AMVN) were less effective against BSA than those deriving from AAPH. Liposomal AMVN radicals could damage MAO, present in a separate membranous phase, though again, less effectively than could AAPH-derived radicals. BSA could be protected by Trolox, the aqueous soluble antioxidant, but hardly by tocopherol itself. Damage to MAO was limited by Trolox, and also by the hydrophobic antioxidant, tocopherol. Damaging reactions due to radicals generated in a membrane phase were significantly accelerated when the membrane was peroxidizable (soybean phosphatidylcholine) rather than nonperoxidizable (saturated dimyristoyl phosphatidylcholine). Thus lipid radicals also played some role in protein damage in these systems. BSA was attacked similarly in the presence or absence of liposomes by AAPH. Correspondingly, BSA could inhibit the peroxidation of liposomes induced by AAPH and less efficiently that induced by AMVN.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reductive cleavage and regeneration of the disulfide bonds inStreptomyces subtilisin inhibitor (SSI) as studied by the carbonyl13C NMR resonances of cysteinyl residues

Summary Four enhanced carbonyl carbon resonances were observed whenStreptomyces subtilisin inhibitor (SSI) was labeled by incorporating specifically labeled [1-¹³C]Cys. The¹³C signals were assigned by the¹⁵N,¹³C double-labeling method along with site-specific mutagenesis. Changes in the spectrum of the labeled protein ([C]SSI) were induced by reducing the disulfide bonds with various amounts of dithiothreitol (DTT). The results indicate that, in the absence of denaturant, the Cys⁷¹-Cys¹⁰¹ disulfide bond of each SSI subunit can be reduced selectively. This disulfide bond, which is in the vicinity of the reactive site scissile bond Met⁷³-Val⁷⁴, is more accessible to solvent than the other disulfide bond. Cys³⁵-Cys⁵⁰, which is embedded in the interior of SSI. This half-reduced SSI had 65% of the inhibitory activity of native SSI and maintained a conformation similar to that of the fully oxidized SSI. Reoxidation of the half reduced-folded SSI by air regenerates fully active SSI which is indistinguishable with intact SSI by NMR. In the presence of 3 M guanidine hydrochloride (GuHCl), however, both disulfide bonds of each SSI subunit were readily reduced by DTT. The fully reduced-unfolded SSI spontaneously refolded into a native-like structure (fully reduced-folded state), as evidenced by the Cys carbonyl carbon chemical shifts, upon removing GuHCl and DTT from the reaction mixture. The time course of disulfide bond regeneration from this state by air oxidation was monitored by following the NMR spectral changes and the results indicated that the disulfide bond between Cys⁷¹ and Cys¹⁰¹ regenerates at a much faster rate than that between Cys³⁵ and Cys⁵⁰.Nomenclature of the various states of SSI that are observed in the present study Fully oxidized-folded native or intact (without GuHCl or DTT) - half reduced-folded (Cys⁷¹-Cys¹⁰¹ reduced; DTT without GuHCl) - inversely half reduced-folded (Cys³⁵-Cys⁵⁰ reduced; a reoxidation intermediate from fully reduced-folded state) - fully reduced-unfolded (reduced by DTT in the presence of GuHCl) - fully reduced-folded (an intermediate state obtained by removing DTT and GuHCl from the fully reduced-unfolded SSI reaction mixture)     

1H NMR studies on ferricytochromec 3 fromDesulfovibrio vulgaris Miyazaki F and its interaction with ferredoxin I

Summary The¹H NMR signals of the heme methyl, propionate and related chemical groups of cytochromec ₃ fromDesulfovibrio vulgaris Miyazaki F (D.v. MF) were site-specifically assigned by means of ID NOE, 2D DQFCOSY and 2D TOCSY spectra. They were consistent with the site-specific assignments of the hemes with the highest and second-lowest redox potentials reported by Fan et al. (Biochemistry,29 (1990) 2257–2263). The site-specific heme assignments were also supported by NOE between the methyl groups of these hemes and the side chain of Val¹⁸. All the results contradicted the heme assignments forD.v. MF cytochromec ₃ made on the basis of electron spin resonance (Gayda et al. (1987)FEBS Lett.,217 57–61). Based on these assignments, the interaction of cytochromec ₃ withD.v. MF ferredoxin I was investigated by NMR. The major interaction site of cytochromec ₃ was identified as the heme with the highest redox potential, which is surrounded by the highest density of positive charges. The stoichiometry and association constant were two cytochromec ₃ molecules per monomer of ferredoxin I and 10⁸ M^–2 (at 53 mM ionic strength and 25°C), respectively.     

C-cell follicles of canine thyroid glands studied by PAS reaction and electron microscopy

Summary Small follicles composed solely of C cells were occasionally observed in large C cell groups of dog thyroid glands. The lumina of C-cell follicles were filled with, or contained peripheral depositions of PAS-positive amorphous material, which was similar in ultrastructural features to thyroglobulin-containing colloid in typical thyroid follicles. This indicates that C cells, in addition to secreting calcitonin, produce a glycoprotein that can be stored in the lumina of the follicles.     

α-Guanidinoglutaric Acid in Cobalt-Induced Epileptogenic Cerebral Cortex of Cats

: Guanidino compounds in the cobalt-induced epileptogenic cerebral cortex of cats were fluorometrically analysed by a JASCO G-520 guanidino compounds analyser, and an unknown high peak was observed in the chromatogram that was identical to the peak of authentic α-guanidinoglutaric acid. In another experiment, the substance was extracted from the cobalt focus tissue, converted into dimethylpyrimidyl derivative-butylester, and analysed by a GC/MS technique. The mass spectrum of the substance was identical to the dimethylpyrimidyl derivative of α-guanidinoglutaric acid butylester (M⁺= 365).     

Early development of the cerebral vesicles in man.

Two human embryos which were immediately before and soon after the appearance of the cerebral vesicle were cut into complete serial sections in almost the same direction and studied comparatively. The findings on these two sets of serial sections indicate that the rostral continuations of subthalamus and ventral thalamus along the ventral thalamic sulcus continuing from the sulcus limitans of the midbrain are destined to give rise to the formation of the cerebral vesicle. The rostral continuation of the subthalamus becomes the floor of the interventricular foramen, and that of the ventral thalamus the pallium. The rostral end of the continuation of the subthalamic matrix is not only the site of the beginning of evagination of the cerebral vesicle, but also the site of elevation of the ganglionic hill or striatum. As the evagination of the cerebral vesicle proceeds exceedingly dorsocaudolaterally from the rostral end of the continuation of the ventral thalamus, the elevation of the striatum occurs also in the same direction, getting in touch with the folding of the hemispheric stalk of Kuhlenbeck to enclose the interventricular foramen. Tt is noticed that, at the beginning of evagination, the grade of depression of the nasal pit was always parallel with that of evagniation of the cerebral vesicle.