Increased apical targeting of renal epithelial sodium channel subunits and decreased expression of type 2 11beta-hydroxysteroid dehydrogenase in rats with CCl4-induced decompensated liver cirrhosis

It was hypothesized that dysregulation of renal epithelial sodium channel (ENaC) subunits and/or 11beta-hydroxysteroid dehydrogenase (11betaHSD2) may play a role in the increased sodium retention in liver cirrhosis (LC). Experimental LC was induced in rats by CCl(4) (1 ml/kg, intraperitoneally, twice a week) for 12 wk (protocol 1) or for 11 wk (protocol 2). In both protocols, one group of rats with cirrhosis showed significantly decreased urinary sodium excretion and urinary Na/K ratio (group A), whereas a second group exhibited normal urinary sodium excretion (group B) compared with controls, even though extensive ascites was seen in both groups of rats with cirrhosis. In group A, protein abundance of alpha-ENaC was unchanged, whereas beta-ENaC abundance was decreased in the cortex/outer stripe of outer medulla compared with controls. The gamma-ENaC underwent a complex change associated with increased abundance of the 70-kD band with a concomitant decrease in the main 85-kD band, corresponding to an aldosterone effect. In contrast, no changes in the abundance of ENaC subunit were observed in group B. Immunoperoxidase microscopy revealed an increased apical targeting of alpha-, beta-, and gamma-ENaC subunits in distal convoluted tubule (DCT2), connecting tubule (CNT), and cortical and medullary collecting duct segments in group A but not in group B. Immunolabeling intensity of 11betaHSD2 in the DCT2, CNT, and cortical collecting duct was significantly reduced in group A but not in group B, and this was confirmed by immunoblotting. In conclusion, increased apical targeting of ENaC subunits combined with diminished abundance of 11betaHSD2 in the DCT2, CNT, and cortical collecting duct is likely to play a role in the sodium retaining stage of liver cirrhosis.     

Long-lasting neurological sequelae after lithium intoxication

A combined literature study and correspondence follow-up provided information about the development and further course of long-lasting neurological sequelae after lithium intoxication in 40 patients (28 women and 12 men). The circumstances surrounding the acute intoxications were examined. Possible precipitating circumstances included somatic illness with fever (11 cases), concurrent treatment with low-salt diet and diuretics, major surgery, low food intake, recent start with large lithium doses, acute overdose with suicidal intent, overdose due to pharmacy, laboratory or patient mistakes, and concurrent treatment with large doses of haloperidol in the presence of fever. In five cases no likely precipitant could be found, and in three cases there was no information about the circumstances of the acute intoxication. The neurological sequelae developed following abatement of the acute intoxication and typically showed cerebellar affection with ataxia and scanning speech. Other brain regions could be affected, and peripheral neuropathy occurred. Improvement was in some cases seen during the first 6-12 months, supported psychologically and perhaps also functionally by physiotherapy, speech therapy, and general rehabilitation. The paper ends with a discussion of measures and guidelines to prevent the development of intoxications and permanent neurological sequelae. An Appendix provides warnings and precautions.     

Influence of indomethacin on the distribution of cortisol in man

Summary Simultaneous determinations of free and protein bound plasma cortisol and of the concentrations of cortisol in skin biopsies were performed after treatment with indomethacin. Neither after a single dose nor in patients on continuous treatment, were any consistent changes found in the protein binding of plasma cortisol. However, in patients treated for more than 3 weeks a significantly greater number of skin biopsies were observed with very low concentrations of cortisol. No relation between the free fraction of plasma cortisol and the tissue cortisol could be demonstrated.In vitro experiments showed no alteration of the protein binding of cortisol after the addition of indomethacin to plasma. It is concluded that indomethacin does not have antirheumatic activity because of displacement of the protein bound plasma cortisol as proposed by other workers. However, long term treatment with indomethacin does seem to influence the tissue distribution of cortisol. The possible relationship of this observation is discussed in view of reported fatalities after long continued indomethacin treatment.     

Arylcyanoguanidines as activators of Kir6.2/SUR1K ATP channels and inhibitors of insulin release

Phenylcyanoguanidines substituted with lipophilic electron-withdrawing functional groups, e.g. N-cyano-N'-[3,5-bis-(trifluoromethyl)phenyl]-N' '-(cyclopentyl)guanidine (10) and N-cyano-N'-(3,5-dichlorophenyl)-N' '-(3-methylbutyl)guanidine (12) were synthesized and investigated for their ability to inhibit insulin release from beta cells, to repolarize beta cell membrane potential, and to relax precontracted rat aorta rings. Structural modifications gave compounds, which selectively inhibit insulin release from betaTC6 cells (e.g. compound 10: IC(50) = 5.45 +/- 1.9 microM) and which repolarize betaTC3 beta cells (10: IC(50) = 4.7 +/- 0.5 microM) without relaxation of precontracted aorta rings (10: IC(50) > 300 microM). Inhibition of insulin release from rat islets was observed in the same concentration level as for betaTC6 cells (10: IC(50) = 1.24 +/- 0.1 microM, 12: IC(50) = 3.8 +/- 0.4 microM). Compound 10 (10 microM) inhibits calcium outflow and insulin release from perifused rat pancreatic islets. The mechanisms of action of 10 and 12 were further investigated. The compounds depolarize mitochondrial membrane from smooth muscle cells and beta cell and stimulate glucose utilization and mitochondrial respiration in isolated liver cells. Furthermore, 10 was studied in a patch clamp experiment and was found to activate Kir6.2/SUR1 and inhibit Kir6.2/SUR2B type of K(ATP) channels. These studies indicate that the observed effects of the compounds on beta cells result from activation of K(ATP) channels of the cell membrane in combination with a depolarization of mitochondrial membranes. It also highlights that small structural changes can dramatically shift the efficacy of the cyanoguanidine type of selective activators of Kir6.2/SUR2 potassium channels.     

Vitamin D supplementation to healthy children does not affect serum osteocalcin or markers of type I collagen turnover

AIM: New serum markers have recently been introduced in the assessment of bone turnover. Such measures are osteocalcin, the C-terminal propeptide of type I procollagen (PICP), the N-terminal propeptide of type I procollagen (PINP) and the C-terminal pyridinoline cross-linked telopeptide of type I collagen (ICTP). This study aimed to determine whether supplementation with vitamin D3 to healthy children during the winter affects bone turnover in healthy children measured by serum osteocalcin, PICP, PINP or ICTP. METHODS: 12 girls and 8 boys aged 6.2-13.7 (mean 9.8) y, all proven healthy by medical examination and history, were enrolled in a double-blind, randomized, placebo-controlled, cross-over study with two 4 wk treatment periods and 2 wk washout. Vitamin D3 600 IU was given in one tablet of ABCDin daily. On the last day of the 4 wk periods blood was sampled for assessment of serum osteocalcin, PICP, PINP, ICTP, 25-OH-vitamin D, 1,25-diOH-vitamin D and parathyroid hormone (PTH). RESULTS: During supplementation and placebo periods serum osteocalcin (mean +/- SEM) was 53.9 +/- 5.7 and 54.4 +/- 3.8 microg l(-1) (p = 0.70), PICP was 437+/- 44 and 429 +/- 41 microg l(-1) (p = 0.73), PINP was 579 +/- 56 and 619 +/- 64 microg l(-1) (p = 0.33) and ICTP was 13.4 +/- 0.9 and 13.6 +/- 0.7 microg l(-1) (p = 0.52), respectively. Mean +/- SEM serum 25-OH-vitamin D was 47.0 +/- 2.3 and 33.0 +/- 3.0 nmol l(-1) during vitamin D3 supplementation and placebo (p < 0.001, t = 8.10, 95% CI = 10.3 to 17.6 nmol l(-1)), 1,25-diOH-vitamin D and PTH were 87.5 +/- 4.3 and 92.0 +/- 5.3 pmol l(-1) (p = 0.38), and 3.97 +/- 0.5 and 4.21 +/- 0.4 micromol l(-1) (p = 0.37), respectively. CONCLUSION: Supplementation with 600 IU vitamin D3 to healthy children in the winter does not affect bone turnover as measured by serum osteocalcin, PICP, PINP or ICTP. Vitamin D supplementation to healthy children may not be recommended on the ground of concern for bone turnover.     

The International Union of Toxicology (IUTOX): history and its role in information on toxicology

The International Union of Toxicology (IUTOX) was founded in 1980 in Brussels. The initiative was started by the Society of Toxicology (SOT), USA, and the European Society of Toxicology in 1975 (EST), and the foundation prepared by an Inter Society Liason Committee. Eight National Societies of Toxicology were founding members of IUTOX besides SOT and EST. It now comprises 43 national/regional Societies from all over the world, representing over 20,000 toxicologists. Information has always been a key element in toxicology. Information exchange in IUTOX has evolved from letters and phone calls to fax, e-mail and the use of the Internet. Initially, newsletters were created which were mailed and later displayed on the Web. The website has been developed as a major information tool with many useful links, thereby providing information for the scientific community, the media and the lay public.     

The correlation between negative middle ear pressure and the corresponding conductive hearing loss in children. A 12-month study of 352 unselected 7-year-old children

An epidemiological study of negative middle ear pressure in children made it possible to test its relationship to conductive hearing loss. About 350 children were subjected to a screening procedure recording audiogram and middle ear pressure five times during a 12-month period. Those children who failed to perceive just one tone or who had a middle ear pressure equal to or worse than -150 mmH2O in one or both ears were referred to the Hearing Clinic for conventional audiometry and middle ear pressure measurement each month. By computing the weighted average of the regressions for each child, a straight linear relationship was found between negative pressure and conductive hearing loss. In addition, a frequency dependence was found, the hearing loss being maximal at about 500 Hz. In general, the study shows that tympanometry is of limited value in predicting hearing loss in a child. The threshold for pathology of about -150 mmH2O, being a predisposing factor in secretory otitis media, corresponds to the upper confidence limit of the normal range of hearing loss found in this series. There is no distinct value of negative pressure that clearly distinguishes between normal and pathological condition, but it is concluded that a middle ear pressure worse than -150 mmH2O should be considered a probable hearing handicap.