Transglutaminase 1 gene mutations in Italian patients with autosomal recessive lamellar ichthyosis

We analyzed the transglutaminase 1 gene locus in patients from six unrelated Italian families affected by autosomal recessive lamellar ichthyosis. In two families we identified a novel mutation (E520G) in the gene coding region, a previously reported splicing mutation (A3447G), and the mis-sense mutations S272P and V518M. The latter mutation, hitherto considered disease causing, was found to be a simple polymorphism. Linkage to transglutaminase 1 gene was excluded in two of the other four families examined. Single strand conformational polymorphism analysis of the transglutaminase 1 gene in the remaining two families did not reveal any alteration in the coding region. This finding confirms the genetic heterogeneity of the disease.

Effects of balloon injury on neointimal hyperplasia in streptozotocin-induced diabetes and in hyperinsulinemic nondiabetic pancreatic islet-transplanted rats

BACKGROUND

The mechanisms of increased neointimal hyperplasia after coronary interventions in diabetic patients are still unknown.

METHODS AND RESULTS

Glucose and insulin effects on in vitro vascular smooth muscle cell (VSMC) proliferation and migration were assessed. The effect of balloon injury on neointimal hyperplasia was studied in streptozotocin-induced diabetic rats with or without adjunct insulin therapy. To study the effect of balloon injury in nondiabetic rats with hyperinsulinemia, pancreatic islets were transplanted under the kidney capsule in normal rats. Glucose did not increase VSMC proliferation and migration in vitro. In contrast, insulin induced a significant increase in VSMC proliferation and migration in cell cultures. Furthermore, in VSMC culture, insulin increased MAPK activation. A reduction in neointimal hyperplasia was consistently documented after vascular injury in hyperglycemic streptozotocin-induced diabetic rats. Insulin therapy significantly increased neointimal hyperplasia in these rats. This effect of hyperinsulinemia was totally abolished by transfection on the arterial wall of the N17H-ras-negative mutant gene. Finally, after experimental balloon angioplasty in hyperinsulinemic nondiabetic islet-transplanted rats, a significant increase in neointimal hyperplasia was observed.

CONCLUSIONS

In rats with streptozotocin-induced diabetes, balloon injury was not associated with an increase in neointimal formation. Exogenous insulin administration in diabetic rats and islet transplantation in nondiabetic rats increased both blood insulin levels and neointimal hyperplasia after balloon injury. Hyperinsulinemia through activation of the ras/MAPK pathway, rather than hyperglycemia per se, seems to be of crucial importance in determining the exaggerated neointimal hyperplasia after balloon angioplasty in diabetic animals.

Results and complications of laparoscopic surgery for pediatric varicocele

BACKGROUND

The aim of this study was to evaluate the results and complications of laparoscopic varicocelectomy in children.

METHODS

Over a 36-month period, 211 children underwent laparoscopic treatment of varicocele. Their ages ranged between 6 and 17 years; the varicocele was located on the left side in 209 cases (99.1%) and was bilateral in 2 (0.9%). In 195 patients the laparoscopic transperitoneal approach was used and in 16 retroperitoneoscopy was used. Thirty children (14.2%) underwent ligation of the veins alone, and 181 (85.8%) underwent ligation of testicular veins and artery. In 15 (7.1%) cases an additional procedure was applied during the same operation.

RESULTS

Average operating time was 30 minutes and hospitalization about 24 hours. At an average follow-up of 26 months, there were 19 (9%) postoperative complications: 14 children had a left hydrocele, 3 children a scrotal emphysema, and 2 an umbilical granuloma. There were 5 recurrences of varicocele in our series: 2 (2 of 30, 6.6%) after the Ivanissevitch procedure, and 3 (3 of 181, 1.6%) after Palomo's. Testicular atrophy did not occur in any patient of this series.

CONCLUSIONS

This preliminary experience shows that the results of the laparoscopic approach are comparable to those of the open approach. The ligation of testicular veins and artery is preferable to the ligation of the testicular veins alone. Hydrocele seems to be the most frequent postoperative complication and a potential problem, especially in children operated on with the Palomo procedure.

Pressure-independent enhancement of cardiac hypertrophy in natriuretic peptide receptor A-deficient mice

Mice lacking natriuretic peptide receptor A (NPRA) have marked cardiac hypertrophy and chamber dilatation disproportionate to their increased blood pressure (BP), suggesting, in support of previous in vitro data, that the NPRA system moderates the cardiac response to hypertrophic stimuli. Here, we have followed the changes in cardiac function in response to altered mechanical load on the heart of NPRA-null mice (Npr1-/-). Chronic treatment with either enalapril, furosemide, hydralazine, or losartan were all effective in reducing and maintaining BP at normal levels without affecting heart weight/body weight. In the reverse direction, we used transverse aortic constriction (TAC) to induce pressure overload. In the Npr1-/- mice, TAC resulted in a 15-fold increase in atrial natriuretic peptide (ANP) expression, a 55% increase in left ventricular weight/body weight (LV/BW), dilatation of the LV, and significant decline in cardiac function. In contrast, banded Npr1+/+ mice showed only a threefold increase in ANP expression, an 11% increase in LV/BW, a 0.2 mm decrease in LV end diastolic dimension, and no change in fractional shortening. The activation of mitogen-activated protein kinases that occurs in response to TAC did not differ in the Npr1+/+ and Npr1-/- mice. Taken together, these results suggest that the NPRA system has direct antihypertrophic actions in the heart, independent of its role in BP control.

Persistence of delayed adrenarche in boys with thalassemia

5 years after a previous study, we followed up a group of thalassemic patients, determining DHEA-S levels in peripubertal age, with the aim of evaluating whether adrenarche maturation occurred in boys and advanced in girls. Furthermore, we evaluated the degree of bone mineral density (BMD SDS(BA)) and analyzed growth parameters calculating standard deviation score with respect to bone age (BA) of height (Ht SDS(BA)), sitting height (SH SDSBA), and subischial leg length (SLL SDSBA), body mass index (BMI) and the difference between the values of the previous and the present study (deltaBMI), thyroid function and serum markers of bone metabolism. Our results showed persistent lack of adrenarche (DHEA-S 25+/-9.5 microg/dl) in all 6 boys and the absence of pubertal signs at chronological age (CA) of 12.4+/-1.4 yr and BA of 11.1+/-1.1 yr. Only one boy, 6 months later, showed a testicular volume of 4 ml (Tanner stage G2) with an increase of DHEA-S value (181 microg/dl) at BA 12.8 yr. Body disproportion and severe degree of osteopenia (BMD SDSBA -2.41+/-0.5) were observed in all boys, even though Ht SDSBA (0.14+/-0.8) and markers of bone metabolism were within the normal range. No change in nutritional status was observed (deltaBMI 0.09+/-0.4 kg/m2). In contrast, all the thalassemic girls had DHEA-S values (172.7+/-97.7 microg/dl) within the normal range at BA 12.7 +/-0.6 yr that was similar to CA. Furthermore, the appearance of Tanner stage B2 occurred in each of them at BA, near to CA, of 10.4+/-0.9 yr, and menarche was observed in three of them at mean BA, near to CA, of 11.4+/-0.9 yr. Ht SDSBA was below normal range (-1.11+/-0.8), but SLL SDSBA and SH SDS(BA) values were reduced homogeneously, so that proportional body growth was observed. A significant change in nutritional status was observed (deltaBMI 2.69+/-0.9 kg/m2). Bone density value (BMD SDS(BA) -0.25+/-0.4) was in the normal range. There were no statistically significant differences between boys and girls for ferritin serum levels, blood consumption and desferrioxamine dosage. In conclusion, lack of change in nutritional status, measurable in the form of deltaBMI, but not BMI alone, considered an important physiological regulator of adrenarche, regardless of individual adrenal androgen secretion, could have a key role in the lack of adrenarche persisting in thalassemic boys during peripubertal age. Further follow up is necessary, in particular when boys reach puberty, because delayed adrenarche represents the most intriguing aspect in these patients.

Cardiac overexpression of a G(q) inhibitor blocks induction of extracellular signal-regulated kinase and c-Jun NH(2)-terminal kinase activity in in vivo pressure overload

BACKGROUND

Understanding the cellular signals that initiate cardiac hypertrophy is of critical importance in identifying the pathways that mediate heart failure. The family of mitogen-activated protein kinases (MAPKs), including the extracellular signal-regulated kinases (ERKs), c-Jun NH(2)-terminal kinase (JNK), and p38 MAPKs, may play specific roles in myocardial growth and function.

METHODS AND RESULTS

To determine the mechanism of activation of MAPK pathways during the development of cardiac hypertrophy, we evaluated the induction of MAPK activity after aortic constriction in wild-type and in 2 types of cardiac gene-targeted mice: one overexpressing a carboxyl-terminal peptide of Galpha(q) that inhibits G(q)-mediated signaling (TG GqI mouse) and another overexpressing a carboxyl-terminal peptide of beta-adrenergic receptor kinase-1 that inhibits Gbetagamma signaling (TG betaARKct mouse). Wild-type mice with pressure overload showed an acute induction of JNK, followed by the induction of p38/p38beta at 3 days and ERK at 7 days. Both JNK and p38 activity remained elevated at 7 days after banding. In TG GqI mice, hypertrophy was significantly attenuated, and induction of ERK and JNK activity was abolished, whereas the induction of p38 and p38beta was robust, but delayed. By contrast, all 3 MAPK pathways were activated by aortic constriction in the TG betaARKct hearts, suggesting a role for Galpha(q), but not Gbetagamma.

CONCLUSIONS

Taken together, these data show that the induction of ERK and JNK activity in in vivo pressure-overload hypertrophy is mediated through the stimulation of G(q)-coupled receptors and that non-G(q)-mediated pathways are recruited to activate p38 and p38beta.

DNA fragmentation in mammalian cells exposed to various light ions

Elucidation of how effects of densely ionizing radiation at cellular level are linked to DNA damage is fundamental for a better understanding of the mechanisms leading to genomic damage (especially chromosome aberrations) and developing biophysical models to predict space radiation effects. We have investigated the DNA fragmentation patterns induced in Chinese hamster V79 cells by 31 keV/micrometer protons, 123 keV/micrometer helium-4 ions and gamma rays in the size range 0.023-5.7 Mbp, using calibrated Pulsed Field Gel Electrophoresis (PFGE). The frequency distributions of fragments induced by the charged particles were shifted towards smaller sizes with respect to that induced by comparable doses of gamma rays. The DSB yields, evaluated from the fragments induced in the size range studied, were higher for protons and helium ions than for gamma rays by a factor of about 1.9 and 1.2, respectively. However, these ratios do not adequately reflect the RBE observed on the same cells for inactivation and mutation induced by these beams. This is a further indication for the lack of correlation between the effects exerted at cellular level and the initial yield of DSB. The dependence on radiation quality of the fragmentation pattern suggests that it may have a role in damage repairability. We have analyzed these patterns with a "random breakage" model generalized in order to consider the initial non-random distribution of the DNA molecules. Our results suggest that a random breakage mechanism can describe with a reasonable approximation the DNA fragmentation induced by gamma rays, while the approximation is not so good for light ions, likely due to the interplay between ion tracks and chromatin organization at the loop level.

Amyloid fibrils derived from the apolipoprotein A1 Leu174Ser variant contain elements of ordered helical structure

We recently described a new apolipoprotein A1 variant presenting a Leu174Ser replacement mutation that is associated with a familial form of systemic amyloidosis displaying predominant heart involvement. We have now identified a second unrelated patient with very similar clinical presentation and carrying the identical apolipoprotein A1 mutation. In this new patient the main protein constituent of the amyloid fibrils is the polypeptide derived from the first 93 residues of the protein, the identical fragment to that found in the patient previously described to carry this mutation. The X-ray fiber diffraction pattern obtained from preparations of partially aligned fibrils displays the cross-beta reflections characteristic of all amyloid fibrils. In addition to these cross-beta reflections, other reflections suggest the presence of well-defined coiled-coil helical structure arranged with a defined orientation within the fibrils. In both cases the fibrils contain a trace amount of full-length apolipoprotein A1 with an apparent prevalence of the wild-type species over the variant protein. We have found a ratio of full-length wild-type to mutant protein in plasma HDL of three to one. The polypeptide 1--93 purified from natural fibrils can be solubilized in aqueous solutions containing denaturants, and after removal of denaturants it acquires a monomeric state that, based on CD and NMR studies, has a predominantly random coil structure. The addition of phospholipids to the monomeric form induces the formation of some helical structure, thought most likely to occur at the C-terminal end of the polypeptide.

Influence of primary sedimentation on pre-denitrification system performances

The effects of suppressing primary sedimentation on nitrogen removal efficiency of a pre-denitrification system have been evaluated for a large municipal wastewater treatment plant. Simulations have been carried out using the STOAT model. For both the process schemes with and without primary sedimentation, nitrification efficiencies are calculated for increasing influent loads of COD, total N and suspended solids. The sensitivity analysis shows that for the usual carbon to nitrogen ratios in the raw influent both the process schemes allow the requested removal efficiencies, whereas for significantly high C/N ratios the scheme with primary sedimentation is preferable.

Cellular and functional defects in a mouse model of heart failure

Heart failure and dilated cardiomyopathy develop in mice that lack the muscle LIM protein (MLP) gene (MLP(-/-)). The character and extent of the heart failure that occurs in MLP(-/-) mice were investigated using echocardiography and in vivo pressure-volume (P-V) loop measurements. P-V loop data were obtained with a new method for mice (sonomicrometry) using two pairs of orthogonal piezoelectric crystals implanted in the endocardial wall. Sonomicrometry revealed right-shifted P-V loops in MLP(-/-) mice, depressed systolic contractility, and additional evidence of heart failure. Cellular changes in MLP(-/-) mice were examined in isolated single cells using patch-clamp and confocal Ca(2+) concentration ([Ca(2+)]) imaging techniques. This cellular investigation revealed unchanged Ca(2+) currents and Ca(2+) spark characteristics but decreased intracellular [Ca(2+)] transients and contractile responses and a defect in excitation-contraction coupling. Normal cellular and whole heart function was restored in MLP(-/-) mice that express a cardiac-targeted transgene, which blocks the function of beta-adrenergic receptor (beta-AR) kinase-1 (betaARK1). These data suggest that, despite the persistent stimulus to develop heart failure in MLP(-/-) mice (i.e., loss of the structural protein MLP), downregulation and desensitization of the beta-ARs may play a pivotal role in the pathogenesis. Furthermore, this work suggests that the inhibition of betaARK1 action may prove an effective therapy for heart failure.

Glutathione deficiency potentiates manganese-induced increases in compounds associated with high-energy phosphate degradation in discrete brain areas of young and aged rats

Aging is a factor known to increase neuronal vulnerability to oxidative stress, which is widely accepted as a mechanism of manganese-induced neuronal damage. We previously showed that subchronic exposure to manganese induced greater energy impairment (as revealed by increases in hypoxanthine, xanthine and uric acid levels) in the striatum and brainstem of aged rats vs young rats. This study shows that inhibition of glutathione (GSH) synthesis, by means of buthionine (SR) sulfoximine, decreased GSH levels and increased the ascorbic acid oxidation status in the striatum and limbic forebrain of both young and aged rats. In addition, inhibition of GSH synthesis greatly potentiated the manganese-induced increase in inosine, hypoxanthine, xanthine and uric acid levels in both regions of aged rats; moreover, inhibition of GSH synthesis significantly increased inosine, hypoxanthine, xanthine and uric acid levels in both regions of young rats, compared with the manganese-treated group. These results suggest that an impairment in the neuronal antioxidant system renders young rats susceptible to manganese-induced energetic impairment, and further support the hypothesis that an impairment in this system plays a permissive role in the increase of neuronal vulnerability that occurs with aging.

A comparison of rCBF patterns during letter and semantic fluency

To evaluate the functional neuroanatomies underlying letter and category fluency, 18 normal controls were studied with oxygen-15 water regional cerebral blood flow positron emission tomography. Three counterbalanced conditions each consisted of 6 trials (45 s each): letter fluency (generating words when cued with a particular letter), semantic fluency (generating words when cued with a particular category), and a control condition (generating days of the week and months of the year). Relative to the control, participants activated similar brain regions during both fluency tasks, including the anterior cingulate, left prefrontal regions, thalamus, and cerebellum; reductions were found in parietal and temporal regions. In a direct comparison of the 2 fluency tasks, inferior frontal cortex and temporoparietal cortex (hypothesized to participate in a phonologic loop for accessing word pronunciation) were activated more during letter than semantic fluency, whereas left temporal cortex (associated with access to semantic storage) was activated more during semantic than letter fluency. This study identifies subtle differences in the neural networks underlying letter and semantic fluency that may underlie the dissociation of these abilities in patients.

Final height and body disproportion in thalassaemic boys and girls with spontaneous or induced puberty

The aim of the study was to evaluate whether sex hormone replacement therapy adversely affected final height and body disproportion in thalassaemic boys and girls. Thirty-six patients with spontaneous (SP) or induced puberty (IP) were studied in order to define the pattern of height growth through three observations: the first (A) at the age of 7-9; the second (B) at onset of spontaneous or induced puberty; and the third (C) when final height was reached. We examined 14 females with SP (f-SP) and 8 with IP (f-IP); 7 males with SP (m-SP) and 7 with IP (m-IP). Girls with IP reached the same final height of girls with SP (f-IP 153.8 (4.3) versus f-SP 154.4 (5.5) cm); p > 0.05) close to target height (f-IP 155.9 (5.2) cm versus f-SP 155.5 (3.6) cm). Girls with IP reached the final height at older chronological age (CA) (17.0 (0.6) y) than girls with SP (CA of 15.3 (0.7) y), but at the same bone age (BA) (f-IP 15.1 (0.9) y versus f-SP 14.8 (0.6) y). There was no difference between the two groups for pubertal growth (f-SP 16.2 (7.7) cm versus f-IP 12.2 (7.4) cm (p > 0.05)) that was negatively correlated with both prepubertal growth and BA at onset of puberty in both groups. Values of sitting height (sds) with respect to BA (SHsdsBA) were not significantly different between the two groups, and showed a worsening from the first observation to final height, reaching values around -2 SD, in both groups. Values of subischial leg length (sds) with respect to BA (SLLsdsBA) were in the normal range at both observations in all girls. High serum ferritin levels were observed in both groups (f-SP 3189 (2296) ng/ml and f-IP 3998 (2545) ng/ml; p > 0.05). Also boys with induced puberty reached the same final height of those with spontaneous one (m-IP 160.9 (5.5) cm versus m-SP 161.8 (2.4) cm; p > 0.05), but it was lower than target height in both groups (m-IP 168.1 (4.1) cm versus m-SP 169.6 (3.2) cm). Boys with IP reached final height at CA of 18.6 (1.1) y slightly older than boys with SP (CA 17.2 (0.9) y), but at the same BA (m-IP 15.9 (1.5) y versus m-SP 16.3 (0.8) y). Pubertal growth values were significantly different between boys with SP 18.9 (5.3) cm and those with IP 13.8 (4.9) cm (p < 0.05), but they were negatively correlated with prepubertal growth values in both groups (m-SP r = -0.91; p < 0.002 and m-IP r = -0.51; p < 0.05). SHsdsBA showed a worsening from the first observation to final height, reaching values around -3 SD in both groups, while SLLsdsBA were always in the normal range in all patients. Serum ferritin levels were higher in boys with IP (3400 (1179) ng/ml) than in those with SP (2020 (496) ng/ml).

CONCLUSIONS

Our data showed that: (a) patients of both sexes with induced puberty reached the same final height of patients with spontaneous puberty; (b) all patients showed a body disproportion with truncal shortening and normal leg length that was more severe in boys of both groups at final height; (c) body disproportion was independent of pubertal or prepubertal period of greater height gain, suggesting that sexual steroids replacement therapy did not adversely affect either final height or body disproportion. Further studies, focused on the pathogenesis of the truncal shortening, are necessary in order to acquire more insight into the causes of this impairment.

Novel bioactive sulfated alkene and alkanes from the mediterranean ascidian Halocynthia papillosa

Three sulfated alkene and alkanes-(R)-2,6-dimethylheptyl sulfate (1), 6-methylheptyl sulfate (2a), and (E)-5-octenyl sulfate (3a)-with cytotoxic activity in vitro, have been isolated from the Mediterranean ascidian Halocynthia papillosa. The structures of the new compounds 2a and 3a have been elucidated by spectroscopic analysis.

The solution structure of the C-terminal segment of tau protein

Pathological changes in the microtubule associated protein tau, leading to tau-containing filamentous lesions, are a major hallmark common to many types of human neurodegenerative diseases, including Alzheimer's disease (AD). No structural data are available which could rationalize the extensive conformational changes that occur when tau protein is converted to Alzheimer's paired helical filaments (PHF). The C-terminal portion of tau plays a crucial role in the aggregation of tau into PHF and in the truncation process that generates cytotoxic segments of tau. Therefore, we investigated the solution structure of the hydrophobic C-terminal segment 423-441 of tau protein (PQLATLADEVSASLAKQGL) by 1H 2D NMR spectroscopy. The peptide displays the typical NMR evidence consistent with a alpha-helix geometry with a stabilizing C-capping motif. The reported data represent the first piece of structural information on an important portion of the molecule and can have implications towards the understanding of its pathophysiology.

Disruption of the Rev3l-encoded catalytic subunit of polymerase zeta in mice results in early embryonic lethality

Polymerase zeta (Pol zeta) is an error-prone DNA polymerase [1], which in yeast is involved in trans-lesion synthesis (TLS) and is responsible for most of the ultraviolet (UV) radiation-induced and spontaneous mutagenesis [2-4]. Pol zeta consists of three subunits: REV1, a deoxycytidyl-transferase [5]; REV7, of unclear function [6]; and REV3, the catalytic subunit. REV3 alone is sufficient to carry out TLS, but association with REV1 and REV7 enhances its activity [5, 7]. Experiments using human cells treated with UV radiation indicate also that mammalian Pol zeta is involved in TLS [7]. The peculiar mutagenic activity of Pol zeta [4,7,8] suggests a possible role in somatic hypermutation of immunoglobulin (Ig) genes [9]. Here, we report that, unlike in yeast where the REV3 gene is not essential for life [4], disruption of the mouse homologue (Rev3l) resulted in early embryonic lethality. In Rev3l(-/-) embryos, no haematopoietic cells other than erythrocytes could be identified in the yolk sac. Rev3l(-/-) haematopoietic precursors were unable to expand in vitro and no haematopoietic cells could be derived from the intraembryonic haematogenic compartment (splanchnopleura). Fibroblasts could not be derived from the Rev3l(-/-) embryos, and Rev3l(-/-) embryonic stem (ES) cells could not be obtained. This is the first evidence that an enzyme involved in TLS is critical for mammalian development.

Glutamate and catabolites of high-energy phosphates in the striatum and brainstem of young and aged rats subchronically exposed to manganese

The degradation of high-energy phosphates was recently shown to precede manganese-induced cellular death. We evaluated hypoxanthine, xanthine, uric acid and glutamate levels in the striatum and brainstem of 3- and 20-month-old rats after subchronic oral exposure to manganese (MnCl2, 200 mg/kg/day in young rats, and 50-100 or 200 mg/kg/day in aged rats). Aged rats had higher basal levels of hypoxanthine, xanthine, and glutamate both in the striatum and brainstem than young rats; conversely, basal uric acid levels were lower in the striatum, but higher in the brainstem. Manganese induced a significantly greater increase in hypoxanthine, xanthine, uric acid and glutamate levels in aged rats than in young rats in both brain regions. These findings depict a greater manganese-induced energetic impairment (increases in hypoxanthine and xanthine levels), xanthine oxidase-induced free radical generation (increases in xanthine and uric acid levels), and excitotoxic status (increases in glutamate levels) in aged rats than in young rats. In addition, these findings may also account for a greater manganese toxicity to the nigro-striatal dopaminergic system in aged than in young rats, as shown in a previous work.

Functional and molecular modelling studies of two hereditary fructose intolerance-causing mutations at arginine 303 in human liver aldolase

We have identified a novel hereditary fructose intolerance mutation in the aldolase B gene (i.e. liver aldolase) that causes an arginine-to-glutamine substitution at residue 303 (Arg(303)-->Gln). We previously described another mutation (Arg(303)-->Trp) at the same residue. We have expressed the wild-type protein and the two mutated proteins and characterized their kinetic properties. The catalytic efficiency of protein Gln(303) is approx. 1/100 that of the wild-type for substrates fructose 1,6-bisphosphate and fructose 1-phosphate. The Trp(303) enzyme has a catalytic efficiency approx. 1/4800 that of the wild-type for fructose 1,6-bisphosphate; no activity was detected with fructose 1-phosphate. The mutation Arg(303)-->Trp thus substitution impairs enzyme activity more than Arg(303)-->Gln. Three-dimensional models of wild-type, Trp(303) and Gln(303) aldolase B generated by homology-modelling techniques suggest that, because of its larger size, tryptophan exerts a greater deranging effect than glutamine on the enzyme's three-dimensional structure. Our results show that the Arg(303)-->Gln substitution is a novel mutation causing hereditary fructose intolerance and provide a functional demonstration that Arg(303), a conserved residue in all vertebrate aldolases, has a dominant role in substrate binding during enzyme catalysis.

H(2)(15)O PET validation of steady-state arterial spin tagging cerebral blood flow measurements in humans

Steady-state arterial spin tagging approaches can provide quantitative images of CBF, but have not been validated in humans. The work presented here compared CBF values measured using steady-state arterial spin tagging with CBF values measured in the same group of human subjects using the H(2)(15)O IV bolus PET method. Blood flow values determined by H(2)(15)O PET were corrected for the known effects of incomplete extraction of water across the blood brain barrier. For a cortical strip ROI, blood flow values determined using arterial spin tagging (64+/-12 cc/100 g/min) were not statistically different from corrected blood flow values determined using H(2)(15)O PET (67+/-13 cc/100 g/min). However, for a central white matter ROI, blood flow values determined using arterial spin tagging were significantly underestimated compared to corrected blood flow values determined using H(2)(15)O PET. This underestimation could be caused by an underestimation of the arterial transit time for white matter regions.

Pivagabine decreases stress-related hormone secretion in women with hypothalamic amenorrhea

Stress-induced neuroendocrine activities influence the regulation of endocrine glands and axes. Weight loss-related hypothalamic amenorrhea is a typical stress-induced physiopathological condition. It is characterized by increased adrenal cortex activation and by reduced GH, LH, FSH and gonadal steroid hormone levels. The aim of the present study was to investigate the effects of pivagabine, a neurotropic drug (1800 mg/day for 7 days) or placebo administration on ACTH, cortisol, GH, LH, FSH and PRL plasma levels in patients with hypothalamic amenorrhea related to weight loss. Hormonal parameters and the pulsatile release of cortisol (6-hour pulsatility, sampling every 10 minutes) were evaluated before and after 7 days of treatment. Pivagabine administration significantly reduced mean plasma ACTH (from 21.7+/-1.7 to 15.4+/-1.2 pg/ml, p<0.05) and cortisol levels (from 12.2+/-0.7 to 9.7+/-0.7 ng/ml, p<0.05) and increased GH levels (from 1.4+/-0.5 to 3.0+/-0.9 ng/ml, p<0.05). A significant reduction of cortisol pulse amplitude was observed (p<0.01) while no change in pulse frequency occurred. No changes were observed in placebo-treated subjects. LH, FSH and PRL levels were not modified by placebo or pivagabine administration. In conclusion, in patients with hypothalamic amenorrhea related to weight loss pivagabine induced a significant decrease of cortisol secretion and an increase of GH release by pivagabine administration, suggesting that this drug exerts a specific neuroendocrine modulatory role.

Effect of hypertrophic cardiomyopathy mutations in human cardiac muscle alpha -tropomyosin (Asp175Asn and Glu180Gly) on the regulatory properties of human cardiac troponin determined by in vitro motility assay

The properties of mutant contractile proteins that cause hypertrophic cardiomyopathy (HCM) have been investigated in expression studies and in mouse models. There is growing evidence that the precise isoforms of both the mutated protein and its interacting partners can qualitatively influence the effects of the mutation. We therefore investigated the functional effects of two HCM mutations in alpha -tropomyosin, Asp175Asn and Glu180Gly, in the in vitro motility assay using recombinant human alpha -tropomyosin, expressed with an N-terminal alanine-serine extension (AStm) to mimic acetylation in vivo, and purified native human cardiac troponin. The expected switching off of reconstituted filament movement at pCa9, and switching on at pCa5, was observed with no difference in fraction of filaments motile or filament velocity, between wild-type and mutant filaments. However, we observed increased Ca(2+)sensitivity of fraction of filaments motile using the mutant tropomyosin compared to wild-type (DeltaEC(50)+0.082+/-0. 019 pCa units for Asp175Asn and +0.115+/-0.021 for Glu180Gly). Indirect measurements using immobilized alpha -actinin to retard filament movement showed that filaments reconstituted with mutant AStm produced the same force as wild-type filaments. The results using human cardiac regulatory proteins reveal different effects of the HCM mutations in tropomyosin compared to studies using heterologous systems. By performing parallel experiments using either human cardiac or rabbit skeletal troponin we show that the cardiac-specific phenotype of HCM mutations in alpha -tropomyosin is not the result of more marked functional changes when interacting with cardiac troponin.

Simulation of electrostatic effects in Fab-antigen complex formation

A model based on the Poisson-Boltzmann equation has been used to model electrostatics in Anti-p24 (HIV-1) Fab-antigen association. The ionization state at different pH values has been simulated and the results have been used to estimate the stability at different pH values and to generate electrostatic potential maps at physiological ionic strength. The analysis of the electrostatic potential at the solvent-accessible surface shows that residues involved in binding are mostly found in the highest, but also in lowest potential regions. Brownian dynamics simulations have been used to estimate the enhancement of the association rate due to electrostatics which appears limited (approximately 2 at 150 mM ionic strength and approximately 3 at 15 mM ionic strength). A much more pronounced effect is observed upon increase of the charge of the diffusing particle. These results compare well with results obtained previously in similar studies on different systems and may serve to estimate the expected order of magnitude of electrostatic effects on association rates in antibody-antigen systems.

A comparison of rCBF patterns during letter and semantic fluency

To evaluate the functional neuroanatomies underlying letter and category fluency, 18 normal controls were studied with oxygen-15 water regional cerebral blood flow positron emission tomography. Three counterbalanced conditions each consisted of 6 trials (45 s each): letter fluency (generating words when cued with a particular letter), semantic fluency (generating words when cued with a particular category), and a control condition (generating days of the week and months of the year). Relative to the control, participants activated similar brain regions during both fluency tasks, including the anterior cingulate, left prefrontal regions, thalamus, and cerebellum; reductions were found in parietal and temporal regions. In a direct comparison of the 2 fluency tasks, inferior frontal cortex and temporoparietal cortex (hypothesized to participate in a phonologic loop for accessing word pronunciation) were activated more during letter than semantic fluency, whereas left temporal cortex (associated with access to semantic storage) was activated more during semantic than letter fluency. This study identifies subtle differences in the neural networks underlying letter and semantic fluency that may underlie the dissociation of these abilities in patients.

A new rat model of small vessel stenting

OBJECTIVES

Restenosis is the major complication of coronary angioplasty and stenting. In addition, the small vessel diameter represents a major limitation to the wide use of the technology. The aim of this study was to assess the feasibility and the vascular response of stent deployment in rat small vessels.

METHODS

In 40 Wistar rats (500-550 g) a Nir stent crimped on a 1.5 mm Comet angioplasty balloon catheter was deployed at high pressure in the common carotid artery. Neointimal area, neointima/media ratio and the arterial dimension were assessed immediately and at 7, 14, 21, and 28 days after stenting.

RESULTS

After stent deployment, the neointimal area and the neointima/media ratio increased progressively and peaked at 14 days (p < 0.05 vs 0 and 7 days). Alpha-actin-positive cells were found circumferentially organized on the lumen surface. At 21 and 28 days after stenting, the neointima and the neointima/media ratio were not statistically different compared with the results obtained fourteen days after stent deployment. No significant differences in the area of external elastic lamina were observed during the study period. In contrast, the internal lumen area was reduced significantly at 14, 21, and 28 days after the stent deployment. Subacute thrombosis rate after stent implantation was 26.5 %.

CONCLUSIONS

The results of this study demonstrated that the balloon expandable stents can be safely placed into rat arteries and the reduction of the internal arterial lumen observed after stent deployment was only due to the neointima formation whereas remodeling did not occur.