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Platelet alpha 2- and leucocyte beta 2-adrenoceptors in phaeochromocytoma: effect of tumour removal.

Platelet alpha 2- and leucocyte beta 2-adrenoceptors (as well as noradrenaline and adrenaline plasma levels) were studied in five patients with confirmed phaeochromocytoma using tritiated yohimbine and iodated cyanopindolol, respectively, before and after tumour removal. Patients with phaeochromocytoma had a lower leucocyte iodated cyanopindolol binding than control subjects, but no change in platelet tritiated yohimbine binding. Plasma catecholamine levels were higher than controls. Tumour removal induced a return to normal values of leucocyte iodated cyanopindolol binding and a decrease in plasma catecholamine levels. These results underline the potential interest of leucocyte beta-adrenoceptor quantification in the diagnosis and the follow-up of phaeochromocytoma. Pharmacologically, they show that down-regulation occurs in vivo for leucocyte beta 2-adrenoceptors but not for platelet alpha 2-adrenoceptors.

Adrenal Gland Neoplasms↗

Iodine fortification is related to increased weight-for-age and birthweight in children in Asia.

Severe iodine deficiency causes stunting and mental retardation in utero, but the relation between mild deficiency and child growth is not well known. The use of iodated salt in relation to anthropometric data was examined from recent survey data. After potential confounding factors had been controlled for, significant associations were seen in Bangladesh, India, Nepal, and Sri Lanka. The use of iodated salt was related to increased weight-for-age and mid-upper-arm circumference, most strongly in the second year of life, mainly affecting soft tissue (thinness). The relation with weight-for-age was greater among children of mothers with lower body mass index. The use of iodated salt was related to birthweight in Sri Lanka and in the Philippines, where iodized oil capsules given during pregnancy had a negative effect when used with high levels of iodine in salt. The associations generally were concentrated in large geographic areas, possibly because of interactions with other environmental factors (e.g., selenium and arsenic). The apparent growth response to iodine may reflect functional effects of mild deficiency, which is widespread, possibly including effects on brain development.

Aging↗

[The relationship between the level of hypophyseal adrenocorticotropic activity and the character of the tissue distribution of exogenously labeled ACTH].

Experiments were conducted on rats--intact, adrenalectomized and dexamethasone-treated; a study was made of the dynamics of incorporation into the kidneys, liver, adrenal glands, the thyroid gland and elmination from the blood plasma of iodated corticotropine of the hypophysis (Hum-ACTHid-28, Richter). It was revealed that the character of incorporation and elimination of the exogenous labeled ACTH depended on the state of the adrenocorticotropic activity of the hypophysis of the recipient rats. The period of semielimination of the iodated corticotropin of the hypophysis from the blood plasma of intact rats constituted 11.2 minutes. The hormone was not included into the parenchyma of the adrenal cortex. The rate of excretion through the kidney and catabolism in the liver of labeled ACTH increased with elevation of the level of endogenous ACTH in the blood. The period of semiexcretion of ACTH-I131 from the blood plasma of adrenalectomized animals constuted 6.4 min. With decrease of the level of endogenous ACTH in the blood due to the block of the hypophyseal secretion with decamethasone elimination of exogenous labeled hormone from the circulation was markedly retarded T1/2 = 17 min). Under these conditions ACTH-I131 was incorporated into the tissue of the adrenal cortex for 9 min. A conclusions was drawn that the period of semielimination of the exogenous iodated ACTH could be used as a criterion for the assessment of the adrenocorticotropic activity of the hypophysis of the animals-recipients.

Adrenal Cortex↗

[Aqueous iodine solutions as disinfectants: composition, stability, comparison with chlorine and bromine solution (author's transl)].

The equilibrium concentrations of aqueous iodine solutions in dependence of the total concentration and the pH-value have been calculated with and without regard of the iodate formation. The values obtained by the latter methode enabled by application of the known rate law to calculate the initial rate of the iodate formation and to draw from this conclusions concerning the stability of iodine solutions. On the grounds of these calculations to aqueous iodine solutions in the concentration and pH-range which is relevant for disinfection (greater than 10(-5) M/l, pH 6--9) one can attribute a stability sufficient for the use in practice and - unlike chlorine and bromine solutions - a content of bactericidal "free halogene" which is higher and independent of the pH-value. The disinfecting action of the iodine cation (H2O+J) which is supposed to be very powerful can be neglected because of its low concentration (10(-3)--10(-6%) of the total concentration). Hypoiodic acid which has already been converted into iodate by disproportionation is as good as lost for the disinfection because of the extremely slow reverse reaction.

Bromine↗

[On the usability of N-iodo compounds as disinfectants (author's transl)].

The usability of N-iodo compounds for disinfecting purposes has been investigated with the help of the equilibrium concentrations in aqueous solution, which have been calculated both with and without regard of the iodate formation, and the rate of iodate formation, which has been deduced from the latter. The following conclusions can be drawn: Fresh and diluted aqueous solutions of N-iodo compounds exhibit HOJ-concentrations corresponding with the sum HOJ + J2 ( = "free halogene") in pure iodine solutions, which let expect a similar bactericidal behaviour of this class of compounds. Compared with iodine solutions, however, a higher rate of iodate formation and therefore a less stability of these solutions can be established, which is caused by the throughout higher HOJ-concentration. Observing certain conditions (pH less than 7; C less than 10(-5) M/l) and unless a not to long interacting time is required the stability should be sufficient for disinfecting purposes. Of particular interest is the possibility to investigate, virtually in absence of molecular iodine, the bactericidal action of the HOJ. A common use in practice will depend on the costs, which, as far as the purchasable N-iodo-succinimide is concerned, are very high, hence it should not come at present into consideration as an alternative of the much more inexpensive elemental iodine.

Disinfectants↗

Behaviour of chemically modified sodium channels in frog nerve supports a three-state model of inactivation.

Voltage clamp experiments were done on single myelinated nerve fibres of the frog, Rana esculenta, with 10 mM TEA+ in the external solutions to block potassium channels. Sodium current inactivation was measured in TEA-Ringer solution and after treatment with Anemonia sulcata toxin II (5 microM), internal iodate (20/40 mM), glutaraldehyde (10 mM), chloramine-T (0.6 mM), and 2,4,6-trinitrophenol (1 mM). The diphasic inactivation time course, observed in untreated membranes, is slowed by all these agents in a very similar way. Both time constants are increased and the proportion of inactivation components is changed favouring the slowly inactivating one. Trinitrophenol only slows inactivation, whereas in Anemonia toxin II, internal iodate, glutaraldehyde and chloramine-T inactivation becomes incomplete, so that a persistent current is flowing during depolarizations. None of these agents even at high concentrations however, totally removes inactivation. These modifications of inactivation time course are interpreted as changes of rate constants in a three-state inactivation model with one open and two closed states (o-c-c). After chemical treatment the access to the closed states is impeded and the transitions into the open state are accelerated. If the membrane is depolarized during drug application chloramine-T fails to modify inactivation. The curve relating the steady state inactivation parameter, h infinity, to the conditioning potential, V pp becomes non-monotonic in chloramine-T, i.e. dh infinity/dV pp greater than 0 for V pp greater than 60 mV. Trinitrophenol, which per se fails to produce a persistent current component, increases the persistent current in a fibre pretreated with chloramine-T.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Neural retinal contribution to the slow negative potential of the canine electroretinogram.

To establish the normal waveform of the electrical responses from canine eyes, electroretinograms and the light peak were recorded in hybrid and beagle dogs under general anesthesia and artificial ventilation. The neural retinal and retinal pigment epithelial components were pharmacologically isolated by intravitreal glutamate injection and systemic sodium iodate administration, respectively. The a- and b-waves elicited by either flash or rectangular stimuli, the oscillatory potentials elicited by flash stimuli and the light peak elicited either by a single maintained illumination or by repetitive stimuli were almost identical with those of other vertebrates thus far studied. In contrast, in response to rectangular (several-second duration) stimuli, the c-wave was usually absent and was replaced by a slow cornea-negative potential that had a time course similar to that of the c-wave in other species. This slow negative potential was elicited at such low stimulus intensities that the a-wave was absent, was deepened by an intravenous administration of sodium iodate, was not affected by an intravitreal injection of sodium glutamate and was shallowed during the light peak. These results suggest that the slow negative potential that replaces the c-wave consists of large slow PIII, small retinal pigment epithelial c-wave and negligible contribution from the late photoreceptor potential and the dc component of the PII.

Action Potentials↗

Determination of the diol content of chromatographic supports by capillary electrophoresis.

A capillary electrophoresis (CE) method was developed for determining the diol content of supports used in high-performance affinity or size exclusion chromatography. This method involved oxidizing the diol-bonded support with periodate, followed by the use of CE to separate and quantitate the iodate produced by this reaction. Both the oxidation and separation conditions were considered in optimizing this assay. The final method was performed by reacting a known amount of support with a 20-fold excess of periodate in pH 4.0, 0.5 M acetate buffer, with pyromellitic acid being used as an internal standard. After allowing 5-10 min for oxidation, the mixture was filtered and the filtrate was injected onto a 57 cm x 50 microns I.D. fused-silica capillary operated at 25 kV and containing pH 4.0, 0.5 M acetate as the running buffer. The total separation time was 5 min per run and gave a detection limit of 0.1 mM iodate (or 0.1 mumol diol groups) for a 6-nl injection of a 1-ml reaction mixture. By varying the amount the support that was assayed, this method could be used with either porous or non-porous supports. This technique showed good correlation with an iodometric titration but required much less sample and time to perform.

Benzoates↗

Determination of iodide by derivatization to 4-iodo-N,N-dimethylaniline and gas chromatography-mass spectrometry.

A real-time determination of iodide is proposed which involves the oxidation of iodide with 2-iodosobenzoate in the presence of N,N-dimethylaniline. The reaction is completed within 1 min to yield 4-iodo-N,N-dimethylaniline, which is extracted in cyclohexane and determined by GC-MS. It was also possible to determine iodine by derivatization in the absence of 2-iodosobenzoate, and iodate by its reduction with ascorbic acid to iodide and subsequent derivatization. A rectilinear calibration graph was obtained for 0.02-50 micrograms l-1 iodide with a correlation coefficient of 0.9998. The limit of detection was 8 ng l-1 iodide. The method was applied to the determination of iodate in iodized table salt and free iodide and total iodine in sea-water, and to spiked samples when the recovery was in the range 96.8-104.3% (RSD 1.9-3.6%). A sample clean-up by solid-phase extraction with a LiChrolut EN cartridge is proposed.

Gas Chromatography-Mass Spectrometry↗

Quantitative evaluation for blood-retinal barrier breakdown in experimental retinal vein occlusion produced by photodynamic thrombosis using a new photosensitizer.

Purpose. To establish a rat model of retinal vein occlusion (RVO), we applied photodynamic thrombosis using a new photosensitizer. By measuring the breakdown of the blood-retinal barrier (BRB), we evaluated the model quantitatively. We also investigated how hypertension and retinal pigment epithelium (RPE) influence the breakdown of BRB after RVO. Methods. We modified a slit lamp biomicroscope for photodynamic thrombosis. The light source was changed from white light to argon laser, which made it possible to perform fluorescein angiography (FAG) simultaneously during photodynamic thrombosis. We irradiated with a continuous diode laser to occlude three retinal veins in a rat after PAD-S31 injection. The breakdown of BRB was quantitated by measuring extravasated Evans blue dye in albino and pigmented rats. We compared hypertensive rats (SHR) to normotensive rats (WKY) and sodium iodate-treated rats to normal rats. Results. High photosensitivity of PAD-S31 made it possible to occlude any retinal veins within 120 seconds at a low dose of 10 mg/kg without retinal thermal burn at the occlusion site. Simultaneous FAG enabled us to observe the formation of thrombus during diode laser irradiation. Our measured value of intraretinal Evans blue correlated with the range of serous retinal detachment. Both albino and pigmented rats demonstrated stable and constant values of Evans blue. SHR recovered from the breakdown of BRB after venous occlusion more slowly than WKY. Sodium iodate-treated rats had smaller breakdowns of BRB and recovered earlier than normal rats. Conclusions. In this study, we established the stable and constant rat model of RVO efficiently by using a new photosensitizer. Our simultaneous FAG method was considered to have an advantage of several potential clinical applications. Our rat model of RVO allows us to study factors associated with the recovery from damage by RVO.

Animals↗

Dynamics of environmental supplementation of iodine: four years' experience of iodination of irrigation water in Hotien, Xinjiang, China.

Hotien prefecture, Xinjiang Province, China, in the Taklamakan Desert, is an area of severe iodine deficiency. Because usual methods of iodine supplementation failed here, we began supplementation in 1992 with potassium iodate, which was added to irrigation water (Lancet 1994; 334:107-110). We report 4 y experience with this method in 3 townships that contained a total treated population of 37,000. Potassium iodate was dripped into irrigation water (to a concentration 10-80 microg/l) during a 2- to 4-wk period. During the 3 y that followed, no further supplementation was made, and iodine concentrations increased several fold in crops and plants, sheep and chicken thyroid glands, and meat and in urine of children 2-6 y of age and of women who were of childbearing age. Infant mortality decreased 50%, and sheep production increased 43%. Iodine repletion of soil through irrigation water is an effective and cost-efficient way of providing iodine in appropriate situations.

Adolescent↗

Effect of sodium hypochlorite and five intracanal medications on Candida albicans in root canals.

The aim of this study was to evaluate the effect of 1% sodium hypochlorite and five intracanals medications on Candida albicans harvested inside root canals. The contaminated canals were irrigated with sterile saline solution and then treated as follows: (i) filled with Calen paste (calcium hydroxide/ glycol polyethylene paste); (ii) filled with camphorated paramonochloro phenol (CPMC); (iii) filled with 2% iodine-iodate solution; (iv) filled with tricresol formalin; (v) filled with Calen and CPMC pastes; (vi) irrigation with 1% sodium hypochlorite and filled with no intracanal medication; and (vii) no intracanal medication was used. Canal access and the apical foramen were then sealed with Cavit and the roots were stored in a humid chamber at 37 +/- 1 degree C for 14 days. The canals were reinstrumented and irrigated with sterile saline solution. Sterile paper points were used to transfer the root canal contents to test tubes containing sterile saline solution. Part of the suspension was harvested in Sabouraud dextrose agar with chloramphenicol and incubated at 37 +/- 1 degree C for 48 h. CPMC was effective in 100% of the samples followed in decreasing order of effectiveness by calcium hydroxide with CPMC (70% effective), 1% sodium hypochlorite (70% effective) (p < 0.05), tricresol formalin (60% effective), 2% iodine-iodate solution (50% effective), calcium hydroxide paste (30% effective), and saline + no intracanal medication.

Anti-Infective Agents, Local↗

Pericyte response during choriocapillaris atrophy in the rabbit.

The rabbit and rat choriocapillaris atrophies in response to experimental destruction of the retinal pigment epithelium by intravenous injection of sodium iodate. This provides a convenient model of capillary atrophy. We have observed that pericytes are spared during this process; the atrophy is due to loss of endothelium only. Extensive examination of thin sections obtained 1 day to 11 weeks after administration of iodate showed that pericytes retained their normal relationship to the remnant capillary basement membrane left behind as the endothelial tube atrophied. This was most conspicuously manifested in their retention of processes longitudinally disposed along the sleeves of remnant basement membrane. The processes retained bundles of actin filaments that had dense regions along them and inserted into subplasmalemmal densities at basement membrane attachment sites, i.e. they had the characteristics of stress fibers. The pericytes did not phagocytose the debris of endothelial necrosis, in spite of their known phagocytic abilities. Necrotic endothelial cells were eliminated by sloughing into the capillary lumen. The observations support the idea that the function of pericytes in the choriocapillaris, the major source of nutrition for the retinal photoreceptors, resides in their contractility, and that pericytes do not remove necrotic endothelium during capillary atrophy.

Actins↗

Diffuse reflection infrared Fourier transform (DRIFT) spectra and high-temperature DRIFT spectra of beta-Ni(IO3)2.4H2O, Ni(IO3)2.2H2O, Mg(OH)2, and Zn(OH)F: novel embedding materials.

Diffuse reflection infrared Fourier transform (DRIFT) spectra of the hydroxides Mg(OH)2 and Zn(OH)F and the iodate hydrates beta-Ni(IO3)2.4H2O and Ni(IO3)2.2H2O have been recorded at ambient and high temperature. Spectra without shifts of the band maxima compared to those of conventional infrared transmission spectra and without inversion of the bands were obtained by dilution of the compounds to about 2-10% with an appropriate embedding material. alpha-Al2O3, TiO2, ZrO2, PbF2, MgO, BaO, ZnO, Na2SiO3, SiO2 (aerosil), and powdered copper, aluminum, and magnesium were tested as diluents for hydrates and hydroxides, especially at elevated temperatures, as alternatives for the commonly used KBr. Thus, alpha-Al2O3, PbF2, and powdered copper were established as the most favorable diluents. Using these novel embedding materials, high-temperature DRIFT spectra are obtainable at temperatures not accessible with KBr discs. Dehydration and decomposition of the iodate hydrates under study were shown by change or disappearance of the respective water bands.

Fluorine Compounds↗

Studies on the stability of iodine compounds in iodized salt.

Contributions made by five groups of investigators to the knowledge of the stability of different iodine compounds in salt, and of the extent of the losses of iodine which may occur when iodized salt is exposed to different conditions of storage and use, are discussed by the author.STABILITY OF THE IODINE COMPONENT IN IODIZED SALT IS DETERMINED BY: (1) moisture content of the salt and humidity of the atmosphere; (2) light, heat, and other meteorological factors; (3) impurities in the salt; (4) acidity or alkalinity of the mixture; and (5) the form in which iodine is present.When potassium iodide or sodium iodide is used as the iodizing agent, the iodide content of the salt will remain constant and its distribution will remain uniform for many months if the salt is packed dry in a container with an impervious lining and kept dry, preferably in a cool place and away from strong light. When these conditions cannot be met, it is desirable to iodize salt with potassium iodate. Under adverse conditions of moisture, heat, and sunlight, the iodine content of salt iodized with potassium iodate remains relatively constant.

Hot Temperature↗

PRELIMINARY REPORT OF AN EXPERIMENT IN THE KANGRA VALLEY FOR THE PREVENTION OF HIMALAYAN ENDEMIC GOITRE WITH IODIZED SALT.

This report incorporates the results of an investigation designed to test the effectiveness of potassium iodide and potassium iodate in the control of Himalayan endemic goitre when these compounds are added in small physiological doses to the domestic salt habitually consumed by the people in the endemic belt. In a prospective study lasting five years, a striking reduction in the prevalence of goitre was observed in areas receiving salt fortified with either potassium iodide or potassium iodate. During the same period, goitre prevalence remained unchanged in the control zone, which received plain, unfortified salt. The study has an important bearing on the problem of goitre control in developing countries that use moist, coarsely crystalline salt.

Biomedical Research↗

Effect of drugs in vitro on lysosomal enzyme activities in bovine retinal pigment epithelial cells.

We examined in vitro the effect of several drugs on the activities of lysosomal enzymes in the crude extract of bovine retinal pigment epithelial cells. Acid phosphatase, beta-D-glucuronidase, N-acetyl-beta-D-glucosaminidase, alpha-L-fucosidase, and alpha-D-mannosidase were used as lysosomal enzymes. Sodium iodate at 10(-6), 10(-5) and 10(-4) M, and potassium iodate at 10(-5) and 10(-4) M inhibited acid phosphatase activity. Ferrous chloride at 10(-5) and 10(-4) M suppressed beta-D-glucuronidase activity. Ferric chloride, indomethacin, chloroquine, chlorpromazine, 5-fluorouracil, tobramycin, daunomycin, oxalate and epinephrine had no or only minimal inhibitory effects on the lysosomal enzyme activities examined.

Animals↗

Analysis of immune deviation elicited by antigens injected into the subretinal space.

PURPOSE: To determine whether the subretinal space supports the induction of deviant immune responses to cell-associated and soluble antigens and to elucidate factors influencing the immunologic properties of the subretinal space. METHODS: P815 mastocytoma cells were used as cell-associated antigens and were inoculated into the anterior chamber (AC), the vitreous cavity (VC), the subretinal space, and subconjunctivally in H2-compatible, but minor H-incompatible, BALB/c mice. Ovalbumin, as a soluble antigen, was similarly injected into eyes, after which recipient animals were immunized with ovalbumin and complete Freund's adjuvant. Delayed-type hypersensitivity (DTH) was assessed by ear challenge. To alter the conditions in the subretinal space, the outer blood-retinal barrier was disrupted by compromising retinal pigment epithelial (RPE) cells with a systemic injection of sodium iodate. Immune privilege in the AC was abolished by mild corneal cauterization. RESULTS: Antigen-specific DTH did not develop in mice in which alloantigenic tumor cells or ovalbumin was injected into the AC, the VC, or the subretinal space, and the mice's spleens contained lymphocytes capable of suppressing DTH when adoptively transferred into naive mice. When RPE cells were compromised with sodium iodate, tumor cells or ovalbumin injected into the subretinal space or the VC did not induce immune deviation, although the AC of these eyes still promoted AC-associated immune deviation. By contrast, when immune privilege in the AC was abolished by corneal cauterization, neither tumor cells nor ovalbumin injected into the subretinal space or the VC of eyes elicited immune deviation. CONCLUSIONS: The subretinal space supports immune deviation for histoincompatible tumor cells and soluble protein antigens by actively suppressing antigen-specific DTH. Acute loss of immune privilege in the subretinal space and the VC does not cause loss of privilege in the AC, but abolition of immune privilege in the AC eliminates the capacity of the subretinal space and the VC to support immune deviation to antigens injected locally.

Adoptive Transfer↗