A novel histone deacetylase 8 (HDAC8)-specific inhibitor PCI-34051 induces apoptosis in T-cell lymphomas

We have developed a potent, histone deacetylase 8 (HDAC8)-specific inhibitor PCI-34051 with >200-fold selectivity over the other HDAC isoforms. PCI-34051 induces caspase-dependent apoptosis in cell lines derived from T-cell lymphomas or leukemias, but not in other hematopoietic or solid tumor lines. Unlike broad-spectrum HDAC inhibitors, PCI-34051 does not cause detectable histone or tubulin acetylation. Cells defective in T-cell receptor signaling were still sensitive to PCI-34051-induced apoptosis, whereas a phospholipase C-gamma1 (PLCgamma1)-defective line was resistant. Jurkat cells showed a dose-dependent decrease in PCI-34051-induced apoptosis upon treatment with a PLC inhibitor U73122, but not with an inactive analog. We found that rapid intracellular calcium mobilization from endoplasmic reticulum (ER) and later cytochrome c release from mitochondria are essential for the apoptotic mechanism. The rapid Ca(2+) flux was dependent on PCI-34051 concentration, and was blocked by the PLC inhibitor U73122. Further, apoptosis was blocked by Ca(2+) chelators (BAPTA) and enhanced by Ca(2+) effectors (thapsigargin), supporting this model. These studies show that HDAC8-selective inhibitors have a unique mechanism of action involving PLCgamma1 activation and calcium-induced apoptosis, and could offer benefits including a greater therapeutic index for treating T-cell malignancies.

Effect of altitude on oxygen binding by hemoglobin and on organic phosphate levels

The relationship between oxygen dissociation and 2,3-diphosphoglycerate (2,3-DPG) in the red cell has been studied in subjects moving from low to high altitude and vice versa. Within 24 hr following the change in altitude there was a change in hemoglobin affinity for oxygen; this modification therefore represents an important rapid adaptive mechanism to anoxia. A parallel change occurred in the organic phosphate content of the red cell. While this study does not provide direct evidence of a cause-effect relationship, the data strongly suggest that with anoxia, the observed rise in organic phosphate content of the red cell is responsible for increased availability of oxygen to tissues.

Fps1, a yeast member of the MIP family of channel proteins, is a facilitator for glycerol uptake and efflux and is inactive under osmotic stress

The Saccharomyces cerevisiae FPS1 gene, which encodes a channel protein belonging to the MIP family, has been isolated previously as a multicopy suppressor of the growth defect of the fdp1 mutant (allelic to GGS1/TPS1) on fermentable sugars. Here we show that overexpression of FPS1 enhances glycerol production. Enhanced glycerol production caused by overexpression of GPD1 encoding glycerol-3-phosphate dehydrogenase also suppressed the growth defect of ggs1/tps1 delta mutants, suggesting a novel role for glycerol production in the control of glycolysis. The suppression of ggs1/tps1 delta mutants by GPD1 depends on the presence of Fps1. Mutants lacking Fps1 accumulate a greater part of the glycerol intracellularly, indicating that Fps1 is involved in glycerol efflux. Glycerol-uptake experiments showed that the permeability of the yeast plasma membrane for glycerol consists of an Fps1-independent component probably due to simple diffusion and of an Fps1-dependent component representing facilitated diffusion. The Escherichia coli glycerol facilitator expressed in a yeast fps1 delta mutant can restore the characteristics of glycerol uptake, production and distribution fully, but restores only partially growth of a ggs1/tps1 delta fps1 delta double mutant on glucose. Fps1 appears to be closed under hyperosmotic stress when survival depends on intracellular accumulation of glycerol and apparently opens rapidly when osmostress is lifted. The osmostress-induced High Osmolarity Glycerol (HOG) response pathway is not required for inactivation of Fps1. We conclude that Fps1 is a regulated yeast glycerol facilitator controlling glycerol production and cytosolic concentration, and might have additional functions.

Fps1p controls the accumulation and release of the compatible solute glycerol in yeast osmoregulation

The accumulation of compatible solutes, such as glycerol, in the yeast Saccharomyces cerevisiae, is a ubiquitous mechanism in cellular osmoregulation. Here, we demonstrate that yeast cells control glycerol accumulation in part via a regulated, Fps1p-mediated export of glycerol. Fps1p is a member of the MIP family of channel proteins most closely related to the bacterial glycerol facilitators. The protein is localized in the plasma membrane. The physiological role of Fps1p appears to be glycerol export rather than uptake. Fps1 delta mutants are sensitive to hypo-osmotic shock, demonstrating that osmolyte export is required for recovery from a sudden drop in external osmolarity. In wild-type cells, the glycerol transport rate is decreased by hyperosmotic shock and increased by hypo-osmotic shock on a subminute time scale. This regulation seems to be independent of the known yeast osmosensing HOG and PKC signalling pathways. Mutants lacking the unique hydrophilic N-terminal domain of Fps1p, or certain parts thereof, fail to reduce the glycerol transport rate after a hyperosmotic shock. Yeast cells carrying these constructs constitutively release glycerol and show a dominant hyperosmosensitivity, but compensate for glycerol loss after prolonged incubation by glycerol overproduction. Fps1p may be an example of a more widespread class of regulators of osmoadaptation, which control the cellular content and release of compatible solutes.

Dual system for potassium transport in Saccharomyces cerevisiae

In a newly formulated growth medium lacking Na+ and NH4+, Saccharomyces cerevisiae grew maximally at 5 microM K+. Cells grown under these conditions transported K+ with an apparent Km of 24 microM, whereas cells grown in customary high-K+ medium had a significantly higher Km (2 mM K+). The two types of transport also differed in carbonyl cyanide-m-chlorophenyl hydrazone sensitivity, response to ATP depletion, and temperature dependence. The results can be accounted for either by two transport systems or by one system operating in two different ways.

Comparative genomics and functional analysis of niche-specific adaptation in Pseudomonas putida

Pseudomonas putida is a gram-negative rod-shaped gammaproteobacterium that is found throughout various environments. Members of the species P. putida show a diverse spectrum of metabolic activities, which is indicative of their adaptation to various niches, which includes the ability to live in soils and sediments contaminated with high concentrations of heavy metals and organic contaminants. Pseudomonas putida strains are also found as plant growth-promoting rhizospheric and endophytic bacteria. The genome sequences of several P. putida species have become available and provide a unique tool to study the specific niche adaptation of the various P. putida strains. In this review, we compare the genomes of four P. putida strains: the rhizospheric strain KT2440, the endophytic strain W619, the aromatic hydrocarbon-degrading strain F1 and the manganese-oxidizing strain GB-1. Comparative genomics provided a powerful tool to gain new insights into the adaptation of P. putida to specific lifestyles and environmental niches, and clearly demonstrated that horizontal gene transfer played a key role in this adaptation process, as many of the niche-specific functions were found to be encoded on clearly defined genomic islands.

Distribution of polybrominated diphenyl ethers in human umbilical cord serum, paternal serum, maternal serum, placentas, and breast milk from Madrid population, Spain

Median concentration of total PBDEs in maternal serum, paternal serum, umbilical cord serum, and breast milk samples were 12, 12, 17, and 6.1 ng/g lipid weight (lw) in Vallecas and 9.7, 12, 15, and 5.5 ng/g lw in Getafe. The median value found in placentas was 1.9 ng/g lw (in Vallecas). BDE 47 was the predominant congener in serum samples (maternal, paternal, and umbilical cord), while BDE 209 was predominant in placenta and breast milk samples. BDEs 196 and 197 were detected in most of the placenta and breast milk samples. The results show that PBDEs, like other POPs, can cross the placenta barrier, although the speed of the process seems to differ for each PBDE congeners. The total PBDE concentrations found in this study are consistent with research reported elsewhere. They are in the same range as those recently reported by other European and Asian studies and lower than those conducted in the U.S.A. No significant differences were found (p > 0.05) between regions, sexes, and ages, while statistically significant differences (p < 0.05) were found between maternal serum, umbilical cord serum, and breast milk samples. The presence of PBDEs in cord blood and placenta samples indicates that there is prenatal exposure of PBDEs, which could continue after birth via breast milk.

Ectopic potassium uptake in trk1 trk2 mutants of Saccharomyces cerevisiae correlates with a highly hyperpolarized membrane potential

Null trk1 trk2 mutants of Saccharomyces cerevisiae exhibit a low-affinity uptake of K+ and Rb+. We show that this low-affinity Rb+ uptake is mediated by several independent transporters, and that trk1Delta cells and especially trk1Delta trk2Delta cells are highly hyperpolarized. Differences in the membrane potentials were assessed for sensitivity to hygromycin B and by flow cytometric analyses of cellular DiOC6(3) fluorescence. On the basis of the latter analyses, it is proposed that Trk1p and Trk2p are involved in the control of the membrane potential, preventing excessive hyperpolarizations. K+ starvation and nitrogen starvation hyperpolarize both TRK1 TRK2 and trk1Delta trk2Delta cells, thus suggesting that other proteins, in addition to Trk1p and Trk2p, participate in the control of the membrane potential. The HAK1 K+ transporter from Schwanniomyces occidentalis suppresses the K+-defective transport of trk1Delta trk2Delta cells but not the high hyperpolarization, and the HKT1 K+ transporter from wheat suppresses both defects, in the presence of Na+. We discuss the mechanism involved in the control of the membrane potential by Trk1p and Trk2p and the causal relationship between the high membrane potential (negative inside) of trk1Delta trk2Delta cells and its ectopic transport of alkali cations.

Urinary BPA measurements in children and mothers from six European member states: Overall results and determinants of exposure

For the first time in Europe, both European-wide and country-specific levels of urinary Bisphenol A (BPA) were obtained through a harmonized protocol for participant recruitment, sampling and quality controlled biomarker analysis in the frame of the twin projects COPHES and DEMOCOPHES. 674 child-mother pairs were recruited through schools or population registers from six European member states (Belgium, Denmark, Luxembourg, Slovenia, Spain and Sweden). Children (5-12 y) and mothers donated a urine sample. Information on socio-demographic characteristics, life style, dietary habits, and educational level of the parents was provided by mothers. After exclusion of urine samples with creatinine values below 300 mg/L or above 3000 mg/L, 653 children and 639 mothers remained for which BPA was measured. The geometric mean (with 95% confidence intervals) and 90th percentile were calculated for BPA separately in children and in mothers and were named "European reference values". After adjustment for confounders (age and creatinine), average exposure values in each country were compared with the mean of the "European reference values" by means of a weighted analysis of variance. Overall geometric means of all countries (95% CI) adjusted for urinary creatinine, age and gender were 2.04 (1.87-2.24) µg/L and 1.88 (1.71-2.07) µg/L for children (n=653) and mothers (n=639), respectively. Multiple regression analysis was used to identify significant environmental, geographical, personal or life style related determinants. Consumption of canned food and social class (represented by the highest educational level of the family) were the most important predictors for the urinary levels of BPA in mothers and children. The individual BPA levels in children were significantly correlated with the levels in their mothers (r=0.265, p<0.001), which may suggest a possible common environmental/dietary factor that influences the biomarker level in each pair. Exposure of the general European population was well below the current health-based guidance values and no participant had BPA values higher than the health-based guidance values.

The growth and signalling defects of the ggs1 (fdp1/byp1) deletion mutant on glucose are suppressed by a deletion of the gene encoding hexokinase PII

Yeast cells defective in the GGS1 (FDP1/BYP1) gene are unable to adapt to fermentative metabolism. When glucose is added to derepressed ggs1 cells, growth is arrested due to an overloading of glycolysis with sugar phosphates which eventually leads to a depletion of phosphate in the cytosol. Ggs1 mutants lack all glucose-induced regulatory effects investigated so far. We reduced hexokinase activity in ggs1 strains by deleting the gene HXK2 encoding hexokinase PII. The double mutant ggs1 delta, hxk2 delta grew on glucose. This is in agreement with the idea that an inability of the ggs1 mutants to regulate the initiation of glycolysis causes the growth deficiency. However, the ggs1 delta, hxk2 delta double mutant still displayed a high level of glucose-6-phosphate as well as the rapid appearance of free intracellular glucose. This is consistent with our previous model suggesting an involvement of GGS1 in transport-associated sugar phosphorylation. Glucose induction of pyruvate decarboxylase, glucose-induced cAMP-signalling, glucose-induced inactivation of fructose-1,6-bisphosphatase, and glucose-induced activation of the potassium transport system, all deficient in ggs1 mutants, were restored by the deletion of HXK2. However, both the ggs1 delta and the ggs1 delta, hk2 delta mutant lack detectable trehalose and trehalose-6-phosphate synthase activity. Trehalose is undetectable even in ggs1 delta strains with strongly reduced activity of protein kinase A which normally causes a very high trehalose content. These data fit with the recent cloning of GGS1 as a subunit of the trehalose-6-phosphate synthase/phosphatase complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Degradation of Aux/IAA proteins is essential for normal auxin signalling

The growth substance auxin mediates many cellular processes, including division, elongation and differentiation. PSIAA6 is a member of the Aux/IAA family of short-lived putative transcriptional regulators that share four conserved domains and whose mRNAs are rapidly induced in the presence of auxin. Here PSIAA6 was shown to serve as a dominant transferable degradation signal when present as a translational fusion with firefly luciferase (LUC), with an in vivo half-life of 13.5 min in transgenic Arabidopsis seedlings. In a transient assay system in tobacco protoplasts using steady-state differences as an indirect measure of protein half-life, LUC fusions with full-length PSIAA6 and IAA1, an Aux/IAA protein from Arabidopsis, resulted in protein accumulations that were 3.5 and 1. 0%, respectively, of that with LUC alone. An N-terminal region spanning conserved domain II of PSIAA6 containing amino acids 18-73 was shown to contain the necessary cis-acting element to confer low protein accumulation onto LUC, while a fusion protein with PSIAA6 amino acids 71-179 had only a slight effect. Single amino acid substitutions of PSIAA6 in conserved domain II, equivalent to those found in two alleles of axr3, a gene that encodes Aux/IAA protein IAA17, resulted in a greater than 50-fold increase in protein accumulation. Thus, the same mutations resulting in an altered auxin response phenotype increase Aux/IAA protein accumulation, providing a direct link between these two processes. In support of this model, transgenic plants engineered to over-express IAA17 have an axr3-like phenotype. Together, these data suggest that rapid degradation of Aux/IAA proteins is necessary for a normal auxin response.

Physiological basis for the high salt tolerance of Debaryomyces hansenii

The effects of KCl, NaCl, and LiCl on the growth of Debaryomyces hansenii, usually considered a halotolerant yeast, and Saccharomyces cerevisiae were compared. KCl and NaCl had similar effects on D. hansenii, indicating that NaCl created only osmotic stress, while LiCl had a specific inhibitory effect, although relatively weaker than in S. cerevisiae. In media with low K+, Na+ was able to substitute for K+, restoring the specific growth rate and the final biomass of the culture. The intracellular concentration of Na+ reached values up to 800 mM, suggesting that metabolism is not affected by rather high concentrations of salt. The ability of D. hansenii to extrude Na+ and Li+ was similar to that described for S. cerevisiae, suggesting that this mechanism is not responsible for the increased halotolerance. Also, the kinetic parameters of Rb+ uptake in D. hansenii (Vmax, 4.2 nmol mg [dry weight]-1 min-1; K(m), 7.4 mM) indicate that the transport system was not more efficient than in S. cerevisiae. Sodium (50 mM) activated the transport of Rb+ by increasing the affinity for the substrate in D. hansenii, while the effect was opposite in S. cerevisiae. Lithium inhibited Rb+ uptake in D. hansenii. We propose that the metabolism of D. hansenii is less sensitive to intracellular Na+ than is that of S. cerevisiae, that Na+ substitutes for K+ when K+ is scarce, and that the transport of K+ is favored by the presence of Na+. In low K+ environments, D. hansenii behaved as a halophilic yeast.

Oxidative stress in rats fed a high-fat high-sucrose diet and preventive effect of polyphenols: Involvement of mitochondrial and NAD(P)H oxidase systems

Mitochondrial and NADPH oxidase systems and oxidative stress were investigated in 12 week high-fat high-sucrose (HFHS) diet-fed rats. A protective effect of wine polyphenol (PP) extract was also examined. In liver, maximal activities of CII and CII+III mitochondrial complexes were decreased but NADPH oxidase expression (p22(phox) and p47(phox)) and NADPH oxidase-dependent superoxide anion production were not modified, whereas oxidative stress (lipid and protein oxidation products and antioxidant systems) was increased with HFHS diet. In muscle, anion superoxide production was slightly increased while mitochondrial complex activities and lipid and protein oxidation products were not modified with HFHS diet. In heart, NADPH oxidase expression and superoxide anion production were increased, and maximal activity of mitochondrial respiratory chain complexes or oxidative stress parameters were not modified. Wine polyphenol extract had an inhibiting effect on liver oxidative stress and on heart NADPH oxidase expression and superoxide anion production, and on induction of hepatic steatosis with HFHS diet. Induction of mitochondrial dysfunction could be a primary event in the development of oxidative stress in liver, while in skeletal muscle and in heart the NADPH oxidase system seems to be mainly involved in oxidative stress. Wine polyphenol extract was shown to partially prevent oxidative stress in liver and heart tissues and to nearly completely prevent steatosis development in liver.

Molecular cloning of a gene involved in glucose sensing in the yeast Saccharomyces cerevisiae

Cells of the yeast Saccharomyces cerevisiae display a wide range of glucose-induced regulatory phenomena, including glucose-induced activation of the RAS-adenylate cyclase pathway and phosphatidylinositol turnover, rapid post-translational effects on the activity of different enzymes as well as long-term effects at the transcriptional level. A gene called GGS1 (for General Glucose Sensor) that is apparently required for the glucose-induced regulatory effects and several ggs1 alleles (fdp1, byp1 and cif1) has been cloned and characterized. A GGS1 homologue is present in Methanobacterium thermoautotrophicum. Yeast ggs1 mutants are unable to grow on glucose or related readily fermentable sugars, apparently owing to unrestricted influx of sugar into glycolysis, resulting in its rapid deregulation. Levels of intracellular free glucose and metabolites measured over a period of a few minutes after addition of glucose to cells of a ggs1 delta strain are consistent with our previous suggestion of a functional interaction between a sugar transporter, a sugar kinase and the GGS1 gene product. Such a glucose-sensing system might both restrict the influx of glucose and activate several signal transduction pathways, leading to the wide range of glucose-induced regulatory phenomena. Deregulation of these pathways in ggs1 mutants might explain phenotypic defects observed in the absence of glucose, e.g. the inability of ggs1 diploids to sporulate.

PENTA guidelines for the use of antiretroviral therapy, 2004

There have been few major advances in paediatric HIV management over the last 2 years. Decisions about starting antiretroviral therapy can now be based on a recent large meta-analysis of the predictive value of CD4 and HIV RNA viral load (VL) in nearly 4000 untreated children, which is discussed in these updated guidelines. Risk estimates for progression to AIDS and death using surrogate markers can now be broken down by age, allowing more accurate discussion with families. In addition, there is increasing recognition of the problems of long-term adherence, drug resistance and cumulative toxicity in adults and children. The controversy over whether to treat asymptomatic infants continues. For older children more data on the efficacy of ritonavir boosted protease inhibitor (PI) regimens suggests that these may be the PI option of first choice. There is still no adult or paediatric trial evidence on which to base decisions about whether to start with PI- or non-nucleoside reverse transcriptase inhibitor (NNRTI)- based regimens, but the PENPACT 1 trial, which is addressing this question, is ongoing. There are increasing moves to provide simpler antiretroviral therapy (ART) regimens, including once daily dosing, but these lag behind adult regimens because of the paucity of pharmacokinetic data. Resistance assays should now be performed in all HIV-infected infants exposed to ART in pregnancy. Therapeutic drug monitoring may be very important in children because of high between- and within-child variability in drug absorption and metabolism. A trial to evaluate this should start shortly in Europe (PENTA 14 trial). The value of resistance tests for choice of second-line and subsequent choices of ART regimens remain unproven (the PERA trial will report late in 2004), but resistance assays are increasingly being used. The issue of when to switch therapy also remains unanswered and is being addressed within the PENPACT 1 trial. Regular formal assessment of adherence is now the standard of care, and routine monitoring in the clinic for lipodystrophy syndrome (LDS) and other ART toxicities is increasingly important. These guidelines will be updated again in 2006.

Dengue virus in the brain of a fatal case of hemorrhagic dengue fever

Neurologic complications associated with dengue fever are in general unusual. However, recent reports evidence more frequent neurologic alterations. In Mexico, neurologic involvement has not been reported in dengue cases. This report demonstrates the detection of dengue virus in the brain of a fatal case of dengue hemorrhagic fever. Serotype 4 was detected by immunohistochemistry and by RT-PCR in the inferior olivary nucleus of medulla and in the granular layer of cerebellum. Immunoreactivity was observed in neurons, astrocytes, microglia and endothelial cells. Our results emphasize the importance of neurologic manifestations in patients with dengue fever.

Functional study of the Saccharomyces cerevisiae Nha1p C-terminus

Saccharomyces cerevisiae cells possess an alkali metal cation antiporter encoded by the NHA1 gene. Nha1p is unique in the family of yeast Na+/H+ antiporters on account of its broad substrate specificity (Na+, Li+, K+) and its long C-terminus (56% of the whole protein). In order to study the role of the C-terminus in Nha1p function, we constructed a series of 13 truncated NHA1 versions ranging from the complete one (2958 nucleotides, 985 amino acids) down to the shortest version (1416 nucleotides, 472 amino acids), with only 41 amino acid residues after the last putative transmembrane domain. Truncated NHA1 versions were expressed in an S. cerevisiae alkali metal cation-sensitive strain (B31; ena1-4Delta nha1Delta). We found that the entire Nha1p C-terminus domain is not necessary for either the proper localization of the antiporter in the plasma membrane or the transport of all four substrates (we identified rubidium as the fourth Nha1p substrate). Partial truncation of the C-terminus of about 70 terminal amino acids improves the tolerance of cells to Na+, Li+ and Rb+ compared with cells expressing the complete Nha1p. The presence of the neighbouring part of the C-terminus (amino acids 883-928), rich in aspartate and glutamate residues, is necessary for the maintenance of maximum Nha1p activity towards sodium and lithium. In the case of potassium, the participation of the long C-terminus in the regulation of intracellular potassium content is demonstrated. We also present evidence that the Nha1p C-terminus is involved in the cell response to sudden changes in environmental osmolarity.

TRK2 is not a low-affinity potassium transporter in Saccharomyces cerevisiae

TRK1 and TRK2 encode proteins involved in K+ uptake in Saccharomyces cerevisiae. A kinetic study of Rb+ influx in trk1 TRK2, trk1 TRK2D, and trk1 trk2 mutants reveals that TRK2 shows moderate affinity for Rb+. K(+)-starved trk1 delta TRK2 cells show a low-affinity component accounting for almost the total Vmax of the influx and a moderate-affinity component exhibiting a very low Vmax. Overexpression of TRK2 in trk1 delta TRK2D cells increases the Vmax of the moderate-affinity component, and this component disappears in trk1 delta trk2 delta cells. In contrast, the low-affinity component of Rb+ influx in trk1 delta TRK2 cells is not affected by mutations in TRK2. Consistent with the different levels of activity of the moderate-affinity Rb+ influx, trk1 delta TRK2 cells grow slowly in micromolar K+, trk1 delta TRK2D cells grow rapidly, and trk1 delta trk2 delta cells fail to grow. The existence of a unique K+ uptake system composed of several proteins is also discussed.

Cortical and trabecular bone mineral content in women with endometriosis: effect of gonadotropin-releasing hormone agonist and danazol

Cortical bone (distal radius and ulna) and trabecular bone mineral content of the thoracolumbar vertebrae (T-12 to L-4) were measured with single-photon absorptiometry and quantitative computed tomography, respectively, in 55 women with laparoscopically staged endometriosis before, during, and after treatment with a gonadotropin-releasing hormone agonist (GnRH-a) or danazol. Mean pretreatment potassium phosphate mineral contents of T-12 to L-4 were 174 to 201 mg/ml in stage I to IV endometriosis and were within the 100 to 115th percentile of normal women. Similarly, cortical bone mineral contents were normal and were not significantly affected by either medication. Trabecular bone decreased significantly to 92.6 +/- 1.7% (n = 11, P less than 0.001) and 92.3 +/- 2.5% (n = 7, P less than 0.01) of baseline year after 6 months and 9 months of GnRH-a treatment and remained significantly depressed at 95.8 +/- 1.9% (P less than 0.0025) and 94.8 +/- 2.5% (P less than 0.005) 6 months after stopping treatment. Thus, cortical and trabecular bone mineral contents of women with endometriosis are normal, but treatment with GnRH-a induced significant loss of trabecular bone.

Worsening of hepatic dysfunction as a consequence of repeated hydroxyethylstarch infusions

BACKGROUND/AIMS

Due to its apparent safety and low cost, hydroxyethylstarch (HES) is increasingly used as a volume expander. The aim of this retrospective study was to highlight the risk of hepatic dysfunction after iterative HES infusions.

METHODS

Between April 1996 and April 1998, nine patients were referred for worsening of their clinical condition after repeated HES infusions. Six patients had previous chronic liver disease, cirrhosis in four cases. All patients underwent a liver biopsy.

RESULTS

All post-HES liver biopsies showed diffuse microvacuolization of Kupffer cells, which was associated with focal hepatocyte vacuolization in seven cases. The vacuoles contained periodic acid Schiff positive material at their margins and were lysosomal by electron microscopy. The clinical symptoms of hepatic disease, although difficult to interpret in cirrhotic patients, worsened after HES infusions. Portal hypertension was noted in three non-cirrhotic patients. Serum alkaline phosphatase and gammaglutamyl transferase activities were increased when compared with previous values. Eight patients died, six of them within 1-4 weeks of hepatic failure or septic shock. In the only living patient, symptoms improved after HES withdrawal.

CONCLUSIONS

Repeated administration of HES could favour severe portal hypertension, liver failure and sepsis, particularly in the setting of chronic liver disease. The basis of these adverse effects is the lysosomal storage of HES in Kupffer cells and hepatocytes.

Prevalence and characteristics of Escherichia coli serotype O157:H7 and other verotoxin-producing E. coli in healthy cattle

From February to July of 1994, 328 faecal samples from 32 herds were collected and verotoxin-producing Escherichia coli (VTEC) found on 84% of the farms. The proportion of animals infected varied from 0-63%. VTEC were recovered from 52 (20%) of 257 cows and from 16 (23%) of 71 calves. Although the VTEC belonged to 25 different serogroups, 7 (O8, O20, O22, O77, O113, O126 and O162) accounted for 46% of strains. Nearly 45% of the strains. Nearly 45% of the 83 bovine VTEC strains belonged to serogroups associated with haemorrhagic colitis and haemolytic uraemic syndrome in humans. However, only 2 (2%) of 83 VTEC strains isolated from cattle belonged to enterohaemorrhagic E. coli (EHEC) serotypes (O26:H11 and O157:H7), and only 8 (10%) were positive for the attaching and effacing E. coli (eae) gene sequence. Polymerase chain reaction (PCR) showed that 17 (20%) of VTEC strains carried VT1 genes, 43 (52%) possessed VT2 genes, and 23 (28%) carried both VT1 and VT2 genes. Characterization of VTEC isolates revelated a heterogeneous population in terms of serogroup and toxin type in the positive herds. This study confirms that healthy cattle are a reservoir of VTEC, but, the absence of eae genes in most bovine VTEC strains suggests that they may be less virulent for humans than eae-positive EHEC.

Regulation of potassium fluxes in Saccharomyces cerevisiae

To investigate the regulation of K+ fluxes in Saccharomyces cerevisiae the dependence of K+ efflux and Rb+ influx on [K+]i, pHi, [Na+]i, membrane potential, cell volume, and turgor pressure were studied in cells with different K+ contents. By decreasing the cell volume with osmotic shocks and the cellular pH with butyric acid the following was found. (1) The K+ efflux induced by uncouplers decreases simultaneously with the decrease of the K+ content of the cell, but the process was insensitive to [K+]i, pHi, cell volume and turgor pressure. The internal presence of Na+ inhibited this K+ efflux. (2) The increase of the Vmax of Rb+ influx observed in low-K+ cells is due to the decrease of the pHi and probably mediated by the increase of the activity of the plasma membrane ATPase. The Vmax is independent of [K+]i, [Na+]i, cell volume and turgor pressure. (3) The decrease in the Km of Bt+ influx observed in low-K+ cells does not depend directly on [K+]i, pHi, cell volume or turgor pressure. If Na+ is present, [Na+]i might be directly involved in the regulation of the Km.

Molecular mobility and fragility in indomethacin: a thermally stimulated depolarization current study

PURPOSE

To show that thermally stimulated depolarization currents (TSDC), which is a dielectric experimental technique relatively unknown in the pharmaceutical scientists community, is a powerful technique to study molecular mobility in pharmaceutical solids, below their glass transition temperature (Tg). Indomethacin (Tg = 42 degrees C) is used as a model compound.

METHODS

TSDC is used to isolate the individual modes of motion present in indomethacin, in the temperature range between -165 degrees C and +60 degrees C. From the experimental output of the TSDC experiments, the kinetic parameters associated with the different relaxational modes of motion were obtained, which allowed a detailed characterization of the distribution of relaxation times of the complex relaxations observed in indomethacin.

RESULTS

Two different relaxational processes were detected and characterized: the glass transition relaxation, or alpha-process, and a sub-Tg relaxation, or secondary process. The lower temperature secondary process presents a very low intensity, a very low activation energy, and a very low degree of cooperativity. The fragility index (Angell's scale) of indomethacin obtained from TSDC data is m = 64, which can be compared with other values reported in the literature and obtained from other experimental techniques.

CONCLUSIONS

TSDC data indicate that indomethacin is a relatively strong glass former (fragility similar to glycerol but lower than sorbitol, trehalose, and sucrose). The high-resolution power of the TSDC technique is illustrated by the fact that it detected and characterized the secondary relaxation in indomethacin, which was not possible by other techniques.

High-grade carcinoma component in epithelial-myoepithelial carcinoma of salivary glands clinicopathological, immunohistochemical and flow-cytometric study of three cases

Three cases of epithelial-myoepithelial carcinoma (EMC) with coexisting areas of high grade carcinoma are reported. In two of the cases there was a previous recurrence, and in all three patients there had been a sudden increase in size before final surgery. The typical ductal and myoepithelial components of EMC showed the usual biphasic pattern and the expected immunophenotypes, with expression of wide spectrum cytokeratins, Cam 5.2 and EMA in the ductal part, and muscle-specific actin, smooth muscle actin, S-100 protein, vimentin and cytokeratins in the myoepithelial component. These areas also had a low mitotic count and low proliferation rate as measured by immunohistochemistry and by flow cytometry. Conversely, areas of high-grade tumour had the features of a large cell carcinoma, with focal mucin secretion in two cases. This high-grade component showed an epithelial immunophenotype in two cases, and was negative for all tested markers in the third one. The mitotic counts and the proliferation rates were much higher in these anaplastic areas. One of the patients died 3 months after treatment; another developed lymph node metastases 1 year later and was alive after 6 years of follow-up. The third patient was alive without evidence of disease 7 months after wide surgical resection of the tumour. The possibility of anaplastic transformation in EMC makes thorough sampling mandatory in this type of neoplasm.