Identification and expression profile of a novel alternative splicing of Pax7 in chick skeletal muscle

Pax7 is essential for skeletal muscle myogenesis. The alternative splicing forms of Pax7 were found in human and mouse. In this study, we identified a new alternative splicing of chick Pax7. We named it Pax7-2 and localized it in the nucleus of chick myoblast. In Pax7-2 mRNA, exon 8 of chick Pax7 gene was spliced out. That led to a 22-amino acid deletion in the COOH terminal of Pax7-2 protein compared with Pax7 protein. Luciferase assays demonstrated that chick Pax7 could act as a transactivator and the deleted 22 amino acids in Pax7-2 may belong to the transactivation domain of Pax7. Pax7-2 lost transactivation ability. We detected the expression levels of Pax7-2 in chick pectoralis muscles at different developmental stages and found that the expression of Pax7-2 was at its peak in d-12 chick embryos. The expression levels of Pax7 and Pax-2 in chick pectoralis muscles at different developmental stages had a similar trend across the period under study, although the changes of their expression levels were different. As chicks grew up, Pax7 and Pax7-2 were expressed at much lower levels.

Ydc1p ceramidase triggers organelle fragmentation, apoptosis and accelerated ageing in yeast

Saccharomyces cerevisiae dihydroceramidase Ydc1p hydrolyzes ceramide, resulting in accumulation of free long-chain bases and their phosphates. Yeast mutants lacking YDC1 are characterized by increased chronological lifespan. Moreover, we found YDC1 up-regulated in a yeast mutant displaying reduced chronological lifespan. These data suggest an important role for Ydc1p in chronological lifespan determination in yeast. Mitochondria are known to play an important role in chronological lifespan and apoptosis. In this study we demonstrated that overexpression of YDC1 results in reduced chronological lifespan and increased apoptotic cell death. We found YDC1 overexpression to result in mitochondrial fragmentation and dysfunction. Interestingly, vacuoles also appeared to be fragmented and dysfunctional upon YDC1 overexpressing. Exogenous addition of ceramide to YDC1-overexpressing cultures increased chronological lifespan and restored organelle function. In conclusion, this study describes a direct link between ceramide metabolism in yeast and mitochondrial and vacuolar fragmentation and function, with consequences for chronological lifespan in yeast.

Development of fetal nicotine and muscarinic receptors in utero

The role of acetylcholine in the central and peripheral nervous systems is well established in adults. Cholinergic modulation of vascular functions and body fluid balance has been extensively studied. In the embryo-fetus, cholinergic receptors are widespread in the peripheral and central systems, including smooth muscle and the epithelial lining of the cardiovascular, digestive, and urinary systems, as well as in the brain. Fetal nicotine and muscarinic receptors develop in a pattern (e.g., amount and distribution) related to gestational periods. Cholinergic mechanisms have been found to be relatively intact and functional in the control of vascular homeostasis during fetal life in utero at least during the last third of gestation. This review focuses on the development of fetal nicotine and muscarinic receptors, and provides information indicating that central cholinergic systems are well developed in the control of fetal blood pressure and body fluid balance before birth. Therefore, the development of cholinergic systems in utero plays an important role in fetal vascular regulation, gastrointestinal motility, and urinary control.

Got pure blood in fetal rats?

Have you felt frustration when fetal blood is needed for your studies in rats, or have you been concerned about fetal rat "blood" collected from decapitation? The traditional approach has been to collect fetal blood from decapitation of fetuses. The new method of collecting fetal blood is from the fetal heart, and makes it possible to obtain pure fetal blood at near-term in rodents for fetal studies. This study also demonstrated a significant difference of fetal blood oxygen levels between the traditional and new methods of blood collection.

Single-dose pharmacokinetics and tolerability of alendronate 35- and 70-milligram tablets in children and adolescents with osteogenesis imperfecta type I

CONTEXT

Alendronate (ALN) is a bisphosphonate compound that can be administered orally and has potential use in pediatric osteoporotic conditions.

OBJECTIVE

The objective was to evaluate the pharmacokinetics and single-dose tolerability of ALN in children with osteogenesis imperfecta.

DESIGN

ALN was administered iv and orally in a two-period, randomized crossover study, with doses separated by a 2-wk washout and follow-up carried out within 2 wk after the last ALN dose.

SETTING

The study was conducted at the pediatric metabolic bone research unit at the Shriners Hospital for Children, Montréal, Canada.

PATIENTS

Twenty-four children (aged 4-16 yr; eight girls) with osteogenesis imperfecta type I participated.

INTERVENTIONS

All patients received iv ALN at a dose of 125 mug. In addition, patients weighing less than 40 kg received an oral dose of ALN 35 mg, whereas those weighing 40 kg or more received ALN 70 mg orally.

MAIN OUTCOME MEASURES

Total urinary excretion and oral bioavailability of ALN, blood and urine safety parameters, and adverse events were the main outcome measures.

RESULTS

The total urinary excretion of ALN after the iv dose was similar for both weight groups. The mean oral bioavailability (95% confidence interval) was 0.43% (0.28, 0.64%) for patients weighing less than 40 kg and 0.56% (0.36, 0.87%) for patients weighing 40 kg or more. Eighteen patients reported a total of 44 clinical adverse experiences, none of which were serious. The most common adverse experiences were mild to moderate headache (n = 7), nausea (n = 7), fever (n = 5), and abdominal pain (n = 6). Eighty percent of the adverse experiences (35 of 44) occurred within 48 h of medication administration, 91% (40 of 44) lasted less than 24 h, and 84% (37 of 44) were reported after oral dosing. Laboratory safety monitoring revealed a marginal decrease in absolute lymphocyte count and serum alkaline phosphatase after the study compared with baseline for both weight categories.

CONCLUSIONS

The mean oral bioavailability of 35- and 70-mg ALN tablets was less than 0.6%, comparable to adult studies. Adverse experiences from single-dose ALN were minor, and the drug was generally well-tolerated.

Lipase-mediated stereoselective hydrolysis of stampidine and other phosphoramidate derivatives of stavudine

Enzymatic hydrolysis of stampidine and other aryl phosphate derivatives of stavudine were investigated using the Candida Antarctica Type B lipase. Modeling studies and comparison of the hydrolysis rate constants revealed a chiral preference of the lipase active site for the putative S-stereoisomer. The in vitro anti-HIV activity of these compounds correlated with their susceptibility to lipase- (but not esterase-) mediated hydrolysis. We propose that stampidine undergoes rapid enzymatic hydrolysis in the presence of lipase according to the following biochemical pathway: During the first step, hydrolysis of the ester group results in the formation of carboxylic acid. Subsequent step involves an intramolecular cyclization at the phosphorous center with simultaneous elimination of the phenoxy group to form a cyclic intermediate. In the presence of water, this intermediate is converted into the active metabolite Ala-d4T-MP. We postulate that the lipase hydrolyzes the methyl ester group of the l-alanine side chain to form the cyclic intermediate in a stereoselective fashion. This hypothesis was supported by experimental data showing that chloroethyl substituted derivatives of stampidine, which possess a chloroethyl linker unit instead of a methyl ester side chain, were resistant to lipase-mediated hydrolysis, which excludes the possibility of a direct hydrolysis of stampidine at the phosphorous center. Thus, our model implies that the lipase-mediated formation of the cyclic intermediate is a key step in metabolism of stampidine and relies on the initial configuration of the stereoisomers.

Analysis of transcripts that are differentially expressed in three sectors of the rice root system under water deficit

Short periods of water deprivation can stimulate the growth of seminal and lateral roots in rice, and inhibit the emergence of adventitious roots. Identification of genes in the different tissues that respond to a water deficit may help us to understand the mechanism underlying root growth under conditions when water is scarce. cDNA-amplified fragment length polymorphism (AFLP) analysis was used to profile gene expression upon imposition of water deficit in three types of root tissue from the upland rice variety Azucena: seminal root tips, lateral root zones and adventitious root primordial zones. In all, 121 unique transcript-derived fragments (TDFs) were cloned, and Northern analysis was carried out for 30 TDFs to confirm their expression patterns. Sixty-six TDFs were differentially expressed in all three root samples. Four (AC2, D6, L22 and T23) were up-regulated by water deficit in seminal root tips and lateral root zones, and down-regulated in adventitious root primordial zones, an expression pattern which reflects the phenotypic changes observed in the different root sectors. In contrast, T17 and T37 showed the opposite expression pattern in Azucena: up-regulation in adventitious roots and repression in the other two zones. Functions could be assigned to five of these six TDFs on the basis of homology: they encode an expansin (T37), a fruit-ripening protein similar to ASR (T23), submergence-induced protein 2A (T17), a dehydrin (D6) and a 9- cis -epoxycarotenoid dioxygenase1 (L22), respectively. AC2 did not show a significant match to any known gene. Northern analysis showed that these six clones exhibited expression patterns that differed between the two cultivars tested (Azucena and the lowland variety IR1552) with respect to regulation by water limitation. Furthermore, T17, T37, D6 and T23 mapped within intervals known to contain QTLs (quantitative trait loci) for root growth in rice under water deficit. These genes may regulate or co-regulate the growth and development of the three root zones in a tissue-specific manner, and may play a role in the processes that underlie the early changes in root architecture under conditions of water deprivation.

Surface modification using photocrosslinkable chitosan for improving hemocompatibility

Immobilization of the anticoagulative or antithrombogenic biomolecule has been considered as one of the important methods to improve the blood compatibility of artificial biomaterials. In this study, a novel immobilization reaction scheme was utilized to incorporate O-butyrylchitosan (OBCS) onto the activated glass surface with an aim to develop an anticoagulative substrate. Activation of the glass surface was carried out by silanization and then OBCS was grafted to the silanized surface via a radiation grafting technique. The OBCS-grafted glass surfaces were characterized by electron spectroscopy for chemical analysis (ESCA) and atomic force microscopy (AFM). The blood compatibility of the OBCS-grafted glass was evaluated by platelet rich plasma (PRP) contacting experiments and protein adsorption experiments in vitro. These results have demonstrated that the surface with immobilized OBCS shows much less platelet adhesive and fibrinogen adsorption compared to the control surface. Therefore, the novel reaction scheme proposed here is very promising for future development of an anticoagulative glass substrate.

Effect of stereochemistry on the anti-HIV activity of chiral thiourea compounds

Chiral derivatives of several substituted halopyridyl and thiazolyl PETT compounds were synthesized as non-nucleoside inhibitors of the reverse transcriptase (RT) enzyme (NNRTI) of the human immunodeficiency virus (HIV-1). Molecular modeling studies indicated that because of the asymmetric geometry of the NNRTI binding pocket, the R stereoisomers would fit the NNRTI binding pocket of the HIV-1 RT much better than the corresponding S stereoisomers, as reflected by their 10(4)-fold lower K1 values. The R stereoisomers of several PETT derivatives inhibited recombinant RT in vitro with lower IC(50) values than their enantiomers. The active compounds were further evaluated for their ability to inhibit HIV-1 replication in human peripheral blood mononuclear cells (PBMC). All the R isomers once again showed potent anti-HIV activity and inhibited the replication of the HIV-1 strain HTLVIIIB in peripheral blood mononuclear cells (PBMC) at nanomolar concentrations whereas their enantiomers were substantially less potent. The lead compounds in the respective groups were further tested against the NNRTI-resistant HIV strains, A17 (Y181C mutant), and A17Var (Y181C+K103N mutant) and RT MDR (V106N). The results showed that the lead compounds were several logs more potent than the standard NNRTI nevirapine. Structure-activity relationship studies also revealed a preference for the pyridyl unit with halo substitutions primarily at 5-position demonstrating the importance of regiochemistry. Our data provides experimental evidence that the stereochemistry as well as regiochemistry of NNRTI can profoundly affect their anti-HIV activity.

Microvascular autologous submandibular gland transfer in severe cases of keratoconjunctivitis sicca

The objective is to evaluate the technique of microvascular autologous submandibular gland transfer for the treatment of severe keratoconjunctivitis sicca. From August 1999 to April 2002, 38 patients with severe keratoconjunctivitis sicca were treated by autologous submandibular gland transfer to the temporal region of the skull. The related vessels were anastomosed to the superficial temporal artery and vein. When the vein was too small, venous bridging was applied. Prior to cutting off the gland, the facial artery was preserved and infused with heparin in normal saline after the gland had been freed to allow inspection of the blood oozing from the three veins. This would be helpful in the selection of a relevant vein for anastomosis. Wharton's duct was transplanted to the upper lateral conjunctiva fornix, and the gland was left denervated. Postoperative scintigraphy with Tc99m pertechnetate, follow-up studies, and management of complications were performed. The transplantations were successful in 33 cases, their symptoms of xerophthalmia disappeared. The discomfort resulting from bright light and wind was also relieved. These patients could stop applying artificial tears. In five patients the transplanted glands did not survive. Epiphora occurred in eight cases. They were successfully treated by reducing the size of the graft. Obliteration of Wharton's duct took place in two cases and was treated by the reconstruction of the duct or duct orifice. Microvascular autologous submandibular gland transfer is a lasting and effective solution for severe cases of keratoconjunctivitis sicca.

Comprehensive screening reveals strong and broadly directed human immunodeficiency virus type 1-specific CD8 responses in perinatally infected children

Advances in antiviral therapy have dramatically shifted the demographics of pediatric human immunodeficiency virus type 1 (HIV-1) infection in the developed world, and a growing proportion of perinatally HIV-1-infected children are now entering their second or even third decade of life. Although cellular immune responses to HIV are known to be weak in early infancy, the magnitude, breadth, and specificity of responses later in childhood have not been characterized in detail. We performed a comprehensive characterization of HIV-1-specific CD8 responses in 18 perinatally infected children (age range, 6 to 17 years), most of whom were on antiviral therapy, using both previously defined HIV-1 epitopes and overlapping peptides spanning all HIV-1 proteins. Multispecific responses were detected in all subjects and accounted for a median of 0.25 to 0.3% of all peripheral blood mononuclear cells that was similar to the magnitude seen in HIV-infected adults. CD8 responses were broadly directed at an average of 11 epitopes (range, 2 to 27 epitopes) and targeted nearly all HIV-1 proteins, with the highest proportion in Gag. Responses were readily detected even in those children with suppressed viremia on highly active antiretroviral therapy, although the breadth (P = 0.037) and the magnitude (P = 0.021) were significantly lower in these subjects. Each child recognized only a small minority of the HIV-1 optimal epitopes defined for his or her class I HLA alleles. Together, these data indicate that perinatally infected children who survive infancy mount a robust HIV-1-specific CD8 response that is much stronger than previously thought and is comparable in magnitude and breadth to that of adults. Moreover, this response has the potential to be broadened to target more epitopes, making these children attractive candidates for immunotherapeutic interventions.

Autoimmune thyroid disease susceptibility loci in a large Chinese family

OBJECTIVES

The autoimmune thyroid diseases (AITDs) comprising Graves' disease (GD) and Hashimoto's thyroiditis (HT) are complex genetic diseases, which result from an interaction between predisposing genes and environmental triggers. The aim of our study was to dissect the genetic predisposition to GD and HT in one large Chinese family with multiple members affected with AITD.

PATIENTS

We completed a whole genome screen of a large multiplex Chinese-American family. We enrolled 27 family members from three generations. Eight members were affected with AITD, six had GD and two had HT.

DESIGN

We determined the information limits of the family. Power calculations indicated that the maximum attainable LOD scores were 5.1 assuming dominant inheritance, and 3.4 assuming recessive inheritance. These estimates both assumed 100% penetrance and one gene. Whole genome screening was performed using 400 highly polymorphic and densely spaced microsatellite markers spanning the entire human genome (intermarker distance < 10 cM). Linkage analysis was performed using two-point and multipoint parametric and nonparametric methods.

RESULTS

Initial whole genome screening performed with 400 microsatellite markers identified two markers that showed evidence for linkage to AITD in this family, D11S4191 and D9S175, with two-point LOD scores of 2.31 and 2.05, respectively. Multipoint linkage analysis focusing on the regions containing these markers revealed a maximum multipoint LOD score (MLS) of 2.13 and a nonparametric linkage score (NPL) of 6.1 for D11S4191 and an MLS of 2.01 and NPL of 7.5 for D9S175.

CONCLUSIONS

These results showed that this Chinese family harboured susceptibility loci for AITD which were distinct from those previously found in the Caucasian population. This suggests that different susceptibility loci exist between different ethnic groups. Furthermore, even within a single family from a genetically homogenous population, more than one gene was involved in the genetic susceptibility to AITD, supporting the notion that AITDs are caused by multiple genes of varying influences.

Crystal structure of Bruton's tyrosine kinase domain suggests a novel pathway for activation and provides insights into the molecular basis of X-linked agammaglobulinemia

Bruton's tyrosine kinase is intimately involved in signal transduction pathways regulating survival, activation, proliferation, and differentiation of B lineage lymphoid cells. Mutations in the human btk gene are the cause of X-linked agammaglobulinemia, a male immune deficiency disorder characterized by a lack of mature, immunoglobulin-producing B lymphocytes. We have determined the x-ray crystal structure of the Bruton's tyrosine kinase kinase domain in its unphosphorylated state to a 2.1 A resolution. A comparison with the structures of other tyrosine kinases and a possible mechanism of activation unique to Bruton's tyrosine kinase are provided.

[The effectiveness of prolene patch in hernia prevention following harvesting rectus abdominis myocutaneous flap]

OBJECTIVE

To investigate the effectiveness of polypropylene path (Prolene) in hernia prevention following harvesting of rectus abdominis is myocutaneous flap.

METHODS

From November 1999 to October 2000, Prolene patches were applied in 26 cases to repair the anterior rectus sheath following harvesting free rectus abdominis myocutaneous flap. Data concerning each case included size of rectus flap, defect of rectus sheath, size of patch used, wound healing and complications.

RESULTS

Prolene patch showed good biocompatibility with abdominal tissue. No foreign-body rejection occurred after operation. Seroma developed in 1 case, and was drained bedside without complication. All prolene patches healed well in the body during follow-up. Hernia formation and abdominal bulge were not observed.

CONCLUSION

Prolene patch is a satisfactory material for repair of the anterior rectus sheath after harvesting free rectus abdominis myocutaneous flap.

Phytosphingosine as a specific inhibitor of growth and nutrient import in Saccharomyces cerevisiae

In the yeast Saccharomyces cerevisiae, we have demonstrated a necessary role for sphingolipids in the heat stress response through inhibition of nutrient import (Chung, N., Jenkins, G. M., Hannun, Y. A., Heitman, J., and Obeid, L. M. (2000) J. Biol. Chem. 275, 17229-17232). In this study, we used a combination of pharmacological and genetic approaches to determine which endogenous sphingolipid is the likely mediator of growth inhibition. When cells were treated with exogenous phytosphingosine (PHS, 20 microm) or structurally similar or metabolically related molecules, including 3-ketodihydrosphingosine, dihydrosphingosine, C(2)-phytoceramide (PHC), and stearylamine, only PHS inhibited growth. Also, PHS was shown to inhibit uptake of uracil, tryptophan, leucine, and histidine. Again this effect was specific to PHS. Because of the dynamic nature of sphingolipid metabolism, however, it was difficult to conclude that growth inhibition was caused by PHS itself. By using mutant yeast strains defective in various steps in sphingolipid metabolism, we further determined the specificity of PHS. The elo2Delta strain, which is defective in the conversion of PHS to PHC, was shown to have slower biosynthesis of ceramides and to be hypersensitive to PHS (5 microm), suggesting that PHS does not need to be converted to PHC. The lcb4Delta lcb5Delta strain is defective in the conversion of PHS to PHS 1-phosphate, and it was as sensitive to PHS as the wild-type strain. The syr2Delta mutant strain was defective in the conversion of DHS to PHS. Interestingly, this strain was resistant to high concentrations of DHS (40 microm) that inhibited the growth of an isogenic wild-type strain, demonstrating that DHS needs to be converted to PHS to inhibit growth. Together, these data demonstrate that the active sphingolipid species that inhibits yeast growth is PHS or a closely related and yet unidentified metabolite.

Cystic fibrosis transmembrane regulator regulates uptake of sphingoid base phosphates and lysophosphatidic acid: modulation of cellular activity of sphingosine 1-phosphate

Sphingolipids have been implicated in the regulation of cell growth, differentiation, and programmed cell death. Sphingosine 1-phosphate (SPP) has recently emerged as an important lipid messenger and a ligand for the endothelial differentiation gene receptor family of proteins through which it mediates its biologic effects. Recent studies in Saccharomyces cerevisiae in our laboratory implicated the yeast oligomycin resistance gene (YOR1), a member of the ATP binding cassette family of proteins, in the transport of SPP. The cystic fibrosis transmembrane regulator is a unique member of the ATP binding cassette transporter family and has high homology with YOR1. We therefore set out to investigate if this member of the family can regulate SPP transport. We demonstrate that C127/cystic fibrosis transmembrane regulator (CFTR) cells, expressing wild type CFTR, exhibited significantly higher uptake of sphingosine 1-phosphate than either cells expressing a mutant CFTR C127/DeltaF508 or C127/mock-transfected cells. This effect was specific, dose-dependent, and competed off by dihydrosphingosine 1-phosphate and lysophosphatidic acid. There was no difference in uptake of sphingosine, C(16)-ceramide, sphingomyelin, lysophingomyelin, phosphatidylcholine, lysophosphatidylcholine, or phosphatidic acid among the different cell lines. Pretreatment with forskolin or isobutylmethylxanthine to stimulate cAMP did not affect the uptake in any of the cell lines. Moreover, we found that mitogen-activated protein kinase activation by SPP was less responsive in C127/CFTR as compared with C127/mock-transfected cells, suggesting that uptake of SPP by CFTR may divert it from interacting with its cell surface receptors and attenuate signaling functions. Taken together, these data implicate CFTR in uptake of SPP and the related phosphorylated lipids dihydrosphingosine 1-phosphate and lysophosphatidic acid. This uptake influences the availability of SPP to modulate biologic activity via endothelial differentiation gene receptors. These studies may have important implications to cystic fibrosis.