[Tin compounds in pharmacy and nutrition]

The occurrence of tin in plants, animals and humans is discussed, in relation to its abundance in the lithosphere and hydrosphere and the range of the different tin(II) and tin(IV) complexes formed. A reasoned consideration of its essentiality for living species is provided. It is concluded that tin is beneficial, even if not yet proved to be an essential element. After reference to the chemistry of tin compounds, there is a detailed discussion of their toxicity in animals and humans. Feasible routes for tin intake and uptake into humans are described. The past and current use of tin pharmaceuticals is reviewed and the areas for which they are currently permitted for use in humans as dentifrices and mouth washes, as radio-pharmaceuticals and for the treatment of jaundiced newborns are described. A detailed review of tin-containing antitumour agents as representative tin pharmaceuticals is also given. Finally, a list of tin-containing drugs and drug candidates is also shown.

Scanning electrochemical microscopy: a new way of making electrochemical experiments

A short review is given on scanning electrochemical microscopy (SECM). The historic background of the technique is briefly summarized and the basic principles outlined. The three different directions of its use: chemical microscopic imaging, the measuring of physicochemical constants and coefficients, and use as a micromachining tool are briefly discussed. The general built-up of the SECM apparatus is described. Preparation and use of several different measuring tips are introduced. A few examples are given of the application of SECM measurement in different studies.

Mechanism of corepressor binding and release from nuclear hormone receptors

The association of transcription corepressors SMRT and N-CoR with retinoid and thyroid receptors results in suppression of basal transcriptional activity. A key event in nuclear receptor signaling is the hormone-dependent release of corepressor and the recruitment of coactivator. Biochemical and structural studies have identified a universal motif in coactivator proteins that mediates association with receptor LBDs. We report here the identity of complementary acting signature motifs in SMRT and N-CoR that are sufficient for receptor binding and ligand-induced release. Interestingly, the motif contains a hydrophobic core (PhixxPhiPhi) similar to that found in NR coactivators. Surprisingly, mutations in the amino acids that directly participate in coactivator binding disrupt the corepressor association. These results indicate a direct mechanistic link between activation and repression via competition for a common or at least partially overlapping binding site.

Regulation of macrophage gene expression by peroxisome-proliferator-activated receptor gamma: implications for cardiovascular disease

The peroxisome-proliferator-activated receptor gamma is a member of the nuclear receptor superfamily that functions as a key transcriptional regulator of cell differentiation and lipid metabolism. In addition, peroxisome-proliferator-activated receptor gamma is now recognized to be the biological receptor for the thiazolidinedione class of antidiabetic drugs, which includes troglitazone and rosiglitazone. Recent evidence indicates that peroxisome-proliferator-activated receptor gamma is expressed at high levels in macrophages, including the foam cells of atherosclerotic lesions. Oxidized low-density lipoprotein, which plays a central role in lesion development, can activate peroxisome-proliferator-activated receptor gamma by providing the cell with oxidized fatty acid ligands of the receptor. The elucidation of a peroxisome-proliferator-activated receptor gamma signalling pathway in macrophages provides a mechanism by which oxidized lipids may directly regulate gene expression in the context of the atherosclerotic lesions. A number of potential target genes for peroxisome-proliferator-activated receptor gamma in these cells have been identified. Some, such as the type B scavenger receptor CD36 are induced by peroxisome-proliferator-activated receptor gamma ligands, whereas others, such as scavenger receptor type A, inducible nitric oxide synthetase and certain cytokines, are repressed. Given the widespread clinical use of thiazolidinediones, it is important to consider the influence of these drugs on the risk of atherosclerosis. The net effect of peroxisome-proliferator-activated receptor gamma ligands on the atherogenic process is likely to reflect a balance between local effects in the artery wall and systemic effects on lipid metabolism.

Effects of nitrogen and phosphorus fertilization in a lowland evergreen rainforest

A nutrient addition experiment was set up in August 1993 in a species-rich primary lowland dipterocarp forest in Barito Ulu, Central Kalimantan, Indonesia. The following treatments were applied: control, +N, +P and +NP. There were five blocks of four 50 m x 50 m plots with a separate treatment for each plot. Fine litterfall was measured on all the plots from 1 May 1994 for 12 months. Litterfall mass and phosphorus concentrations were significantly higher in all the fertilizer treatments compared with the controls. All trees (> or = 10 cm dbh) were measured in August 1993 and in August 1998, and there was no significant girth increment response to fertilization in dipterocarps or non-dipterocarps. Dipterocarps of the red meranti group showed a doubling of girth increment in the +NP treatment, however, the difference from the control fell short of significance.

In vitro and in vivo effects of formamidines in locust (Locusta migratoria migratorioides)

In vivo and in vitro experiments were used to study the effects of formamidines in the locust, Locusta migratoria migratorioides. In vivo the lethal and the antifeeding effects, in vitro the inhibition of the binding of a selective 3H-ligand to the receptors of octopamine, tyramine, dopamine, serotonin and gamma-amino butiric acid were studied. We have demonstrated that demethylchlordimeform is specific agonist to octopamine receptor, having high affinity to octopamine receptor, a moderate affinitiy to tyramine receptor and a low affinity to dopamine, serotonin and to gamma-amino butiric acid receptors. The demethylated chlordimeform analogoues, demethylchlordimeform and didemethylchlordimeform have higher affinity to the octopamine receptor than the parent compound. The formamidines had a toxic and an antifeeding effects when injected into the locust. The half lethal doses (LD50) and the feeding inhibition were correlated with the affinity of the compounds (Ki). The ring substitutions of the mulecule have alterated the both affinity and in vivo effect of the compounds. The most effective ring substitution pattern is 2,4-disubstitution with a combination of methyl groups or halogens. Our results suggest that the lethal effect of formamidines is mediated through the octopamine receptor.

Effect of transfusion on the endothelium dependent dilatation of brachial artery in patients with chronic anemia

The effect of changes in the main determinants of whole blood viscosity after red blood cell transfusion on endothelium dependent dilatation of brachial artery was studied in patients treated with symptoms of chronic anemia. 10 patients were involved in the study, 8 males, 2 females, mean age 52.7+/-18.7 years. Following blood tests performed at hospital admission: hemoglobin (Hgb), red blood cell count (RBC), hematocrit (Hct), white blood cell count, platelet count, plasma total protein, fibrinogen, plasma viscosity, BUN, creatinine, cholesterol, triglycerides. Flow mediated dilatation of brachial artery (FMD) was determined by Doppler method. Blood tests and FMD study were repeated after transfusion. The main determinants of whole blood viscosity increased after transfusion. The increases of Hgb, RBC, Htc were highly significant. The central flow velocity in brachial artery decreased at rest and during hyperemia as well. FMD of brachial artery was not changed significantly after transfusion. The change in factors determining whole blood viscosity did not cause a significant change in FMD. The probable explanation for this is that the increase of whole blood viscosity is associated with a decrease of central flow velocity. These two counteracting changes can equal each other.

Risk factors for psychological stress among international business travellers

OBJECTIVES

This study investigated sources of self reported psychological stress among international business travellers at the World Bank, following up on a previous study showing that travellers submitted more insurance claims for psychological disorders. Hypotheses were that work, personal, family, and health concerns, as well as time zone travel, contribute to travel stress.

METHODS

A travel survey was developed from focus groups and consisted of questions about these potential sources of travel stress. Surveys were sent to a random sample of staff, stratified by number of travel missions, age range, and sex. Canonical correlation analyses estimated the association between key survey items on sources of stress and two measures of travel stress.

RESULTS

498 staff completed the survey. More than a third reported high to very high travel stress. Correlations between predictors and travel stress showed that social and emotional concerns (such as impact of travel on family and sense of isolation) contributed the most to such stress, followed by health concerns, and workload upon return from travel. Surprisingly, time zone travel did not contribute to the self reported stress of these travellers. There were few modifiers of stress, although respondents suggested that a day of rest after travel and reduced workloads would help.

CONCLUSIONS

The current study confirms clinical impressions about several correlates of travel stress. Similar research with travellers in other organisations could help to determine whether the findings from this study are valid and what measures can be taken to reduce the psychological health risks to travellers.

Essential roles of retinoic acid signaling in interdigital apoptosis and control of BMP-7 expression in mouse autopods

We previously reported that mice lacking the RARgamma gene and one or both alleles of the RARbeta gene (i.e., RARbeta+/-/RARgamma-/- and RARbeta-/-/RARgamma-/- mutants) display a severe and fully penetrant interdigital webbing (soft tissue syndactyly), caused by the persistence of the fetal interdigital mesenchyme (Ghyselinck et al., 1997, Int. J. Dev. Biol. 41, 425-447). In the present study, these compound mutants were used to investigate the cellular and molecular mechanisms involved in retinoic acid (RA)-dependent formation of the interdigital necrotic zones (INZs). The mutant INZs show a marked decrease in the number of apoptotic cells accompanied by an increase of cell proliferation. This marked decrease was not paralleled by a reduction of the number of macrophages, indicating that the chemotactic cues which normally attract these cells into the INZs were not affected. The expression of a number of genes known to be involved in the establishment of the INZs, the patterning of the autopod, and/or the initiation of apoptosis was also unaffected. These genes included BMP-2, BMP-4, Msx-1, Msx-2, 5' members of Hox complexes, Bcl2, Bax, and p53. In contrast, the mutant INZs displayed a specific, graded, down-regulation of tissue transglutaminase (tTG) promoter activity and of stromelysin-3 expression upon the removal of one or both alleles of the RARbeta gene from the RARgamma null genetic background. As retinoic acid response elements are present in the promoter regions of both tTG and stromelysin-3 genes, we propose that RA might increase the amount of cell death in the INZs through a direct modulation of tTG expression and that it also contributes to the process of tissue remodeling, which accompanies cell death, through an up-regulation of stromelysin-3 expression in the INZs. Approximately 10% of the RARbeta-/- /RARgamma-/- mutants displayed a supernumerary preaxial digit on hindfeet, which is also a feature of the BMP-7 null phenotype (Dudley et al., 1995, Genes Dev. 9, 2795-2807; Luo et al., 1995, Genes Dev. 9, 2808-2820). BMP-7 was globally down-regulated at an early stage in the autopods of these RAR double null mutants, prior to the appearance of the digital rays. Therefore, RA may exert some of its effects on anteroposterior autopod patterning through controlling BMP-7 expression.

Acquired C1 inhibitor deficiency associated with systemic lupus erythematosus, secondary antiphospholipid syndrome and IgM monoclonal paraproteinaemia

In this case report, a woman is described who developed systemic lupus erythematosus at the age of 36 years affecting the central nervous system and kidneys, showing the serological evidence of an acquired C1 inhibitor deficiency, but also developing an antiphospholipid syndrome and IgM lambda type paraproteinemia. During the 25 years follow-up she did not show any signs of angioedema. Although the immunological abnormalities are still constantly present, the disease has been quiescent since the past three years. The possible pathophysiology of clinical and laboratory features are discussed.

No association between D2 dopamine receptor (DRD2) "A" system alleles, or DRD2 haplotypes, and posttraumatic stress disorder

BACKGROUND

Association studies between marker alleles at the D2 dopamine receptor gene (DRD2) and various psychiatric illnesses have produced conflicting results. Reports of allelic associations were originally made with alcoholism, but were then extended to other psychiatric disorders, including posttraumatic stress disorder (PTSD).

METHODS

We studied allele frequency of the DRD2 TaqI "A," "B," and "D" system markers in 52 European-American subjects with diagnoses of PTSD (based on structured interviews).

RESULTS

Frequency of the A1 allele in this sample was .15, not significantly different from the .19 allele frequency seen in 87 control subjects. We were thus unable to replicate the previous reports of allelic association between the DRD2 TaqI "A1" allele and PTSD. There were also no significant differences in allele frequency for the "B" or "D" systems. We then computed three marker (TaqI "A," "B," and "D" system) haplotypes for the sample; DRD2 haplotype frequencies also did not differ between control subjects and subjects with PTSD.

CONCLUSIONS

We conclude that DRD2 alleles are not associated with PTSD in this sample, and that genetic variation at the DRD2 locus is not likely to be an important contributor to risk for this disorder.

[Unusual coordination behavior of D-fructose towards dimethyltin(IV)2+: metal-promoted deprotonation of alcoholic hydroxyl groups in aqueous solutions at low pH]

To study the effect of the conformation of sugar hydroxy groups on metal complexation processes, complex formation of eight saccharides (D-fructose, L-sorbose, L-arabinose, D-arabinose, D-glucose, D-sorbitol, 2-deoxy-D-glucose and D-saccharose) with dimethyltin(IV)2+ cations was investigated in aqueous solution by potentiometric equilibrium measurements, 13C NMR, polarimetric and Mössbauer spectroscopic methods. The experimental results proved that deprotonation of D-fructose and L-sorbose is caused by the coordination of dimethyltin(IV)2+ in the unusual low pH interval 4-6 in contrast to the other saccharides deprotonated in analogous way at pH > 8. Increasing the pH of the solution resulted in the formation of further complexes. Stability and composition of the species was determined by potentiometric studies. 13C NMR measurements led to the assignment of the sugar OH groups participating in the processes. Mössbauer investigations in the quick-frozen solutions permitted the determination of the stereochemistry of tin(IV) in the complexes.

[Comparative pharmacokinetics of 800 mg of acyclovir-containing Telviran and Zovirax tablets in healthy volunteers]

The authors performed a detailed comparative clinical and pharmacokinetic study with two 800 mg acyclovir containing tablets, namely the Telviran (EGIS Pharmaceuticals Ltd.) and the Zovirax (Wellcome Foundation Ltd.). The determination of the detailed pharmacokinetic parameters and the relative bioavailability was carried out on 24 healthy male volunteers in a two way, open, randomised, cross-over design study after single dose administration. The plasma concentration of acyclovir was determined by a newly developed and validated highly sensitive (LLOQ = 10 ng/ml) HPLC-UV bioanalytical method after sample preparation with RP-18 solid phase extraction method (SPE). The individual pharmacokinetic parameters calculated from the time-plasma concentration curve (tmax, Cmax, AUC0-infinity, AUC0-16, AUC0-t, AUC0-z, AUCRest, t beta 1/2, MRT, Cmax/AUC0-infinity) were compared with statistical methods (ANOVA, ANOVAlog, Confidence interval, Schuirmann, Wilcoxon tests). On the basis of the results of the statistical evaluation and the clinical study, there was no significant difference found between the two acyclovir containing preparations. The comparative pharmacokinetic study demonstrated, that the relative bioavailability of the 800 mg Telviran and Zovirax tablets are equivalent and the two products are bioequivalent.

[Effect of chronic anemia on the endothelium-dependent dilatation of the brachial artery]

The effect of changes in main determinants of whole blood viscosity after red blood cell transfusion on endethel dependent dilatation of brachial artery was studied in patients treated with transfusion because of symptoms of chronic anaemia.

PATIENTS AND METHODS

10 patients were involved, 8 females 2 males, mean age 50.9 +/- 16.6 years. Following blood tests were performed at hospital admission: hemoglobin, red blood cell count, heamatocrit, white blood cell count, platelet count, plasma total protein, fibrinogen, plasma viscosity, blood urea nitrogen, creatinine, cholesterol, triglicerides. Flow mediated dilatation of brachial artery was determined, too. Blood tests and flow mediated dilatation study were repeated after transfusion.

RESULTS

The main determinants of whole blood viscosity increased after transfusion. The increase of hemoglobin, red blood cell count, hematocrit were highly significant. The central flow velocity in brachial artery decreased at rest and during hyperemia as well. The flow mediated dilatation of brachial artery wasn't significantly changed by transfusion.

CONCLUSIONS

Change of determinants of whole blood viscosity caused by transfusion didn't change the flow mediated dilatation of brachial artery. The probable reason for this that the increase of whole blood viscosity in associated with the decrease of central flow velocity. These two counteracting changes probably equal each other.

[Instability of the distal radio-ulnar joint]

Instability of the distal radioulnar joint is caused either by bone deformity, fracture or by ligament deficiency. The logical treatment will consist either in osteotomy, osteosynthesis, or in reconstruction of the ligamentous support. The refixation of the TFCC or the ulnar styloid has been demonstrated to be effective in correcting instability biomechanically and clinically. Near-anatomical TFCC reconstruction should always be striven for, rather than resorting to non-anatomical reconstructive procedures. Nevertheless, great efforts will be necessary in the future in order to better understand biomechanics, epidemiology, diagnosis, and treatment of distal radioulnar joint instability.

Arrhythmic effects of intermittent dobutamine therapy in chronic heart disease failure. The Working Group of Cardiology of the Academic Committee of Veszprém, Hungary

It is known that intermittent dobutamine therapy improves the symptoms and physical condition of patients with chronic heart failure, but its arrhythmogenic effect is insufficiently described. The aim of this study was to assess ventricular arrhythmias and the condition of patients before, during, and after intermittent dobutamine therapy. The 23 patients participating in the study were in New York Heart Association functional classes III and IV despite therapy with digitalis, diuretics, and angiotensin-converting enzyme inhibitors. Starting dosage of dobutamine was 2 microg/kg/min, which was raised gradually up to 12 microg/kg/min, or until the appearance of complaints or symptoms. In group I (7 patients), for 24 hours before dobutamine infusion, Holter monitoring had been performed. In the subsequent 24 hours, during the infusion, patients were monitored in the critical care unit, but the second Holter test was performed only after the infusion, i.e., in the third 24 hours. In group II (16 patients), the Holter monitoring was started 4 hours before dobutamine infusion and was continued for an additional 20 hours, during the drug administration. In the 24 hours after dobutamine treatment, another Holter monitoring was performed. There was no increase in frequency of ventricular arrhythmias after the dobutamine infusion compared with the preinfusion period, but during dobutamine administration, ventricular arrhythmias occurred more frequently than in the preinfusion and postinfusion periods. No ventricular fibrillation was observed in the 23 patients. In conclusion, ventricular arrhythmias are frequent in congestive heart failure, and dobutamine infusion increases their incidence. The arrhythmogenic effect of dobutamine subsides on the day after the dobutamine infusion. Because of the arrhythmogenic effect of dobutamine, admission to the critical care unit is suggested during the infusion, but monitoring is not necessary after the end of the infusion.

Tyrosine phosphatase inhibitors, vanadate and pervanadate, stimulate glucose transport and GLUT translocation in muscle cells by a mechanism independent of phosphatidylinositol 3-kinase and protein kinase C

Vanadate and pervanadate (pV) are protein tyrosine phosphatase (PTP) inhibitors that mimic insulin to stimulate glucose transport. To determine whether phosphatidylinositol (PI) 3-kinase is required for vanadate and pV, as it is for insulin, cultured L6 myotubes were treated with vanadate and pV. The two compounds stimulated glucose transport to levels similar to those stimulated by insulin; however, while PI 3-kinase activity and the increase in the lipid products PI 3,4-bisphosphate and PI 3,4,5-trisphosphate were inhibited by wortmannin after stimulation by all three agents--insulin, vanadate, and pV--wortmannin blocked glucose transport stimulated by insulin but not vanadate or pV. Vanadate and pV stimulated the translocation of GLUTs from an intracellular compartment to the plasma membrane; this stimulation was not blocked by wortmannin, but insulin-induced GLUT translocation was inhibited. Similar results were obtained in cultured H9c2 cardiac muscle cells in which wortmannin did not inhibit glucose transport or the vanadate-induced translocation of GLUT4 in c-myc-GLUT4 transfected cells. The ser/thr kinase PKB (Akt/PKB/RAC-PK) is activated by insulin, lies downstream of PI 3-kinase, and has been implicated in signaling of glucose transport. Insulin and pV stimulated PKB activity, and both were inhibited by wortmannin. In contrast, vanadate, at concentrations that maximally stimulated glucose transport, did not significantly increase PKB activity. To determine the potential role of protein kinase C (PKC), L6 cells were incubated chronically with phorbol myristate acetate (PMA) or acutely with the PKC inhibitors calphostin C and bisindolylmaleimide. There was no inhibition of glucose transport stimulation by insulin, vanadate, or pV, and a combination of wortmannin and PKC inhibitors also failed to block the effect of vanadate and pV. In contrast, disassembly of the actin network with cytochalasin D blocked the stimulation of glucose transport by all three agents. In conclusion, vanadate and pV are able to stimulate glucose transport and GLUT translocation by a mechanism independent of PI 3-kinase and PKC. Similar to that by insulin, glucose transport stimulation by vanadate and pV requires the presence of an intact actin network.

Retention behaviours and separation of carboxylic acids by ion-exchange chromatography

The use of high-performance suppressed ion chromatography for the separation of aliphatic carboxylic acids has become an attractive and viable method during the past years. This paper summarises and critically concludes that some new results have been achieved in separation and detection of low-molecular-mass organic anions. Theoretical and practical considerations of ion-exchange selectivity to control retention behaviour are presented. The major factors that determine the separation ability of ion-exchange chromatography (pKa values, the aliphatic nature and valency of solutes, eluent pH and the chemical composition of stationary phases) are discussed. The question of isocratic vs. gradient elution and different separation modes are examined briefly. The potentials and limitations of the developed methods and their specific application areas are outlined.

[Is panarthrodesis the gold standard in wrist joint surgery?]

In order to determine the value of panarthrodesis, 109 cases have been reviewed. Relevant complications occurred in 36%, whereof 20 were serious entailing reoperations. The procedure was most rewarding in patients with inflammatory arthritis which were mostly painfree and regained full strength, whereas in cases following trauma and avascular necrosis of the lunate, only 56% were painfree, and only 6% achieved contralateral strength. In comparison with 52 cases which had undergone procedures preserving wrist motion, the results were not different with regard to pain relief and strength, whereas in the patients treated accordingly, a functional amount of wrist motion could be preserved.

Insect (Locusta migratoria migratorioides) test monitoring the toxicity of cyanobacteria

An insect test was developed to investigate the toxicity of cyanobacteria. The African locust, Locusta migratoria migratorioides R.F. was used as a test animal instead of mouse. The cyanobacteria tested were Aphanizomenon flos-aque, Anabaena aphanizomenoides, Cylindrospermopsis raciborskii, Microcystis aeruginosa. The toxicity of authentic microcystin-LR was also tested. Cyanobacteria producing toxins killed the animals when the homogenized cell suspension was injected into the animals. The locust test proved to be more sensitive than the mouse test. The LD50 values of the different cyanobacteria for locusts and for mice, respectively were the following: 90 microg/animal (60 mg/kg) and 8000 microg/animal (320 mg/kg), for Aphanizomenon flos-aquae; 255 microg/animal (170.2 mg/kg) and 3750 microg/animal (150 mg/kg), for Anabaena aphanizomenoides; 195 microg/animal (131.4 mg/kg) and 5750 microg/animal (230 mg/kg), for Cylindrospermopsis raciborskii; 22.5 microg/animal (15 mg/kg) and 6000 microg/ animal (240 mg/kg), for Microcystis aeruginosa. In locusts the LD50 value for authentic microcystin-LR was 0.2 microg/animal (130 mg/kg). Since the weight of the mice is 15 to 20 times larger than that of the locusts, hence less toxic cells are needed to kill the locusts. The locust test is cheaper than the mouse test, large number of animals can be used in the experiments and the LD50 values can be estimated more precisely. The toxicity of C. raciborskii was significantly lower when the lyophilized cells were extracted in methanol (LD50 = 767 mg/kg), instead of NaCl solution (LD50 = 131.4 mg/kg).