The MDM2 gene amplification database

The p53 tumor suppressor gene is inactivated in human tumors by several distinct mechanisms. The best characterized inactivation mechanisms are: (i) gene mutation; (ii) p53 protein association with viral proteins; (iii) p53 protein association with the MDM2 cellular oncoprotein. The MDM2 gene has been shown to be abnormally up-regulated in human tumors and tumor cell lines by gene amplification, increased transcript levels and enhanced translation. This communication presents a brief review of the spectrum of MDM2 abnormalities in human tumors and compares the tissue distribution of MDM2 amplification and p53 mutation frequencies. In this study, 3889 samples from tumors or xenografts from 28 tumor types were examined for MDM2 amplification from previously published sources. The overall frequency of MDM2 amplification in these human tumors was 7%. Gene amplification was observed in 19 tumor types, with the highest frequency observed in soft tissue tumors (20%), osteosarcomas (16%) and esophageal carcinomas (13%). Tumors which showed a higher incidence of MDM2 amplification than p53 mutation were soft tissue tumors, testicular germ cell cancers and neuro-blastomas. Data from studies where both MDM2 amplification and p53 mutations were analyzed within the same samples showed that mutations in these two genes do not generally occur within the same tumor. In these studies, 29 out of a total of 33 MDM2 amplification-positive tumors had wild-type p53. We hypothesize that heretofore uncharacterized carcinogens favor MDM2 amplification over p53 mutations in certain tumor types. A database listing the MDM2 gene amplifications is available on the World Wide Web at http://www. infosci.coh.org/mdm2 . Charts of MDM2 amplification frequencies and comparisons with p53 genetic alterations are also available at this Web site.

Defective propagation of signals generated by sympathetic nerve stimulation in the liver of connexin32-deficient mice

The gap junctional protein connexin32 is expressed in hepatocytes, exocrine pancreatic cells, Schwann cells, and other cell types. We have inactivated the connexin32 gene by homologous recombination in the mouse genome and have generated homozygous connexin32-deficient mice that were viable and fertile but weighed on the average approximately 17% less than wild-type controls. Electrical stimulation of sympathetic nerves in connexin32-deficient liver triggered a 78% lower amount of glucose mobilization from glycogen stores, when compared with wild-type liver. Thus, connexin32-containing gap junctions are essential in mouse liver for maximal intercellular propagation of the noradrenaline signal from the periportal (upstream) area, where it is received from sympathetic nerve endings, to perivenous (downstream) hepatocytes. In connexin32-defective liver, the amount of connexin26 protein expressed was found to be lower than in wild-type liver, and the total area of gap junction plaques was approximately 1000-fold smaller than in wild-type liver. In contrast to patients with connexin32 defects suffering from X chromosome-linked Charcot-Marie-Tooth disease (CMTX) due to demyelination in Schwann cells of peripheral nerves, connexin32-deficient mice did not show neurological abnormalities when analyzed at 3 months of age. It is possible, however, that they may develop neurodegenerative symptoms at older age.

Diet, physical activity, and colorectal cancer among Chinese in North America and China

In a population-based case-control study of colorectal cancer among Chinese men and women in western North America and the People's Republic of China, a common protocol was used to assess past life-style characteristics of 905 cases diagnosed during 1981-1986 and 2,488 controls. Risks for cancers of both the colon and rectum increased with increased food energy from fat, protein, carbohydrate, and all energy sources combined, for both sexes and on both continents. Yet, in multivariate analysis, colorectal cancer risk was significantly associated only with saturated fat; no relationships were seen with other dietary sources of energy. Colon cancer risk was elevated among men employed in sedentary occupations. On both continents and in both sexes, risks for cancers of both the colon and rectum increased with increasing time spent sitting. Further, the association between colorectal cancer risk and saturated fat was stronger among the sedentary than among the active. Risk among sedentary Chinese Americans of either sex increased more than fourfold from the lowest to the highest category of saturated fat intake. Among migrants to North America, risk increased with increasing years lived in North America. These observations suggest (a) that colorectal cancer risk increases with duration of exposure to a sedentary life-style and a diet rich in saturated fat; (b) that higher incidence among Chinese-American men relative to women is due to longer duration of these habits among men, who have lived longer in North America; and (c) that higher risk among Chinese Americans of both sexes relative to risk among the general population in China is due to differences in such habits. Attributable risk calculations suggest that, if these associations are causal, saturated fat intakes exceeding 10 g/day, particularly in combination with physical inactivity, could account for 60% of colorectal cancer incidence among Chinese-American men and 40% among Chinese-American women.

Identification and characterization of the dystrophin anchoring site on beta-dystroglycan

Dystrophin, the product of the Duchenne muscular dystrophy gene, is tightly associated with the sarcolemmal membrane to a large glycoprotein complex. One function of the dystrophin-glycoprotein complex is to link the cytoskeleton to the extracellular matrix in skeletal muscle. However, the molecular interactions of dystrophin with the membrane components of the dystrophin-glycoprotein complex are still elusive. Here, we demonstrate and characterize a specific interaction between beta-dystroglycan and dystrophin. We show that skeletal muscle and brain dystrophin as well as brain dystrophin isoforms specifically bind to beta-dystroglycan. To localize and characterize the dystrophin and beta-dystroglycan interaction domains, we reconstituted the interaction in vitro using dystrophin fusion proteins and in vitro translated beta-dystroglycan. We demonstrated that the 15 C-terminal amino acids of beta-dystroglycan constituted a unique binding site for the second half of the hinge 4 and the cysteine-rich domain of dystrophin (amino acids 3054-3271). This dystrophin binding site is located in a proline-rich environment of beta-dystroglycan within amino acids 880-895. The identification of the interaction sites in dystrophin and beta-dystroglycan provides further insight into the structure and the molecular organization of the dystrophin-glycoprotein complex at the sarcolemma membrane and will be helpful for studying the pathogenesis of Duchenne muscular dystrophy.

Transplacental uptake of glucose is decreased in embryonic lethal connexin26-deficient mice

Mice that harbor a targeted homozygous defect in the gene coding for the gap junctional protein connexin26 died in utero during the transient phase from early to midgestation. From day 10 post coitum onwards, development of homozygous embryos was retarded, which led to death around day 11 post coitum. Except for growth retardation, no gross morphological alterations were detected between homozygous connexin26-defective embryos and wild-type littermates. At day 9 postcoitum, when chorioallantoic placenta started to function, connexin26 was weakly expressed in the yolk sac epithelium, between syncytiotrophoblasts I and II in the labyrinth region of the placenta, and in the skin of the embryo. At day 10 post coitum, expression of connexin26 in the placenta was much stronger than at the other locations. To analyze involvement of connexin26 in the placental transfer of nutrients, we have measured embryonic uptake of the nonmetabolizable glucose analogue 3-O-[14C]methylglucose, injected into the maternal tail vein. At day 10 post coitum, viable, homozygous connexin26-defective embryos accumulated only approximately 40% of the radioactivity measured in wild-type and heterozygous littermates of the same size. We conclude that the uptake of glucose, and presumably other nutrients as well, from maternal blood into connexin26-deficient mouse embryos was severely impaired and apparently not sufficient to support the rapid organogenesis during midgestation. Our results suggest that connexin26 gap junction channels likely fulfill an essential role in the transfer of maternal nutrients and embryonic waste products between syncytiotrophoblast I and II in the labyrinth layer of the mouse placenta.

SH3 domain-mediated interaction of dystroglycan and Grb2

Dystroglycan is a novel laminin receptor that links the extracellular matrix and sarcolemma in skeletal muscle. The dystroglycan complex containing alpha- and beta-dystroglycan also serves as an agrin receptor in muscle, where it may regulate agrin-induced acetylcholine receptor clustering at the neuromuscular junction. beta-Dystroglycan has now been expressed in vitro and shown to directly interact with Grb2, an adapter protein involved in signal transduction and cytoskeletal organization. Protein binding assays with two Grb2 mutants, Grb2/P49L and Grb2/G203R, which correspond to the loss-of-function mutants in the Caenorhabditis elegans sem-5, demonstrated that the dystroglycan-Grb2 association is through beta-dystroglycan C-terminal proline-rich domains and Grb2 Src homology 3 domains. Affinity chromatography has also shown endogenous skeletal muscle Grb2 interacts with beta-dystroglycan. Immunoprecipitation experiments have demonstrated that Grb2 associates with alpha/beta-dystroglycan in vivo in both skeletal muscle and brain. The specific dystroglycan-Grb2 interaction may play an important role in extracellular matrix-mediated signal transduction and/or cytoskeleton organization in skeletal muscle that may be essential for muscle cell viability.

Elimination of polychlorinated dibenzo-p-dioxins and dibenzofurans in occupationally exposed persons

The elimination of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) was investigated in a group of n = 43 exposed workers with 2 blood measurements and n = 5 workers with 3 measurements. Under the assumption of a one-compartment, first-order kinetic model the median half-life for 2,3,7,8-TCDD was 7.2 yr, while for the other dioxins the estimates were between 3.7 yr for 1,2,3,4,6,7,8-HpCDD (hepta-chlorinated) and 15.7 yr for 1,2,3,7,8-PCDD (penta-chlorinated). For the furans median half-lives between 3.0 yr for 1,2,3,4,6,7,8-HpCDF and 19.6 yr for 2,3,4,7,8-PCDF were observed. There was no indication for a deviation from a first-order kinetic. Increasing age and percent body fat were associated with increasing half-life for most of the congeners. Smokers in general had a faster decay than non- and ex-smokers. In summary, the higher chlorinated PCDD/F like TCDD appear to be highly persistent in humans with half-lives ranging between 4 and 12 yr.

Size Matters More Than Chemistry for Cloud-Nucleating Ability of Aerosol Particles

Size-resolved cloud condensation nuclei (CCN) spectra measured for various aerosol types at a non-urban site in Germany showed that CCN concentrations are mainly determined by the aerosol number size distribution. Distinct variations of CCN activation with particle chemical composition were observed but played a secondary role. When the temporal variation of chemical effects on CCN activation is neglected, variation in the size distribution alone explains 84 to 96% of the variation in CCN concentrations. Understanding that particles' ability to act as CCN is largely controlled by aerosol size rather than composition greatly facilitates the treatment of aerosol effects on cloud physics in regional and global models.

Human ileal bile acid transporter gene ASBT (SLC10A2) is transactivated by the glucocorticoid receptor

BACKGROUND

Patients with Crohn's disease suffer from intestinal bile acid malabsorption. Intestinal bile acid absorption is mediated by the apical sodium dependent bile acid transporter ASBT/IBAT (SLC10A2). In rats, ASBT is induced by glucocorticoids.

AIMS

To study whether human ASBT is activated by glucocorticoids and to elucidate the mechanism of regulation.

PATIENTS AND METHODS

ASBT expression in ileal biopsies from patients with Crohn's disease and from healthy subjects was quantified by western blot. ASBT promoter function was studied in luciferase assays and by electrophoretic mobility shift assay.

RESULTS

In 16 patients with Crohn's disease, ASBT expression was reduced to 69 (7.5)% compared with healthy controls (mean (SEM); p = 0.01). In 10 healthy male volunteers, ASBT protein expression was increased 1.34 (0.11)-fold (mean (SEM); p<0.05) after 21 days' intake of budesonide (9 mg/day) whereas expression of the peptide transporter 1 was unaffected. Reporter constructs of the human ASBT promoter were activated 15-20-fold by coexpression of the glucocorticoid receptor (GR) and exposure to the GR ligands dexamethasone or budesonide. Two glucocorticoid response elements in the ASBT promoter, arranged as inverted hexanucleotide repeats (IR3 elements), conferred inducibility by GR and dexamethasone in a heterologous promoter context and were shown to bind GR in mobility shift assays.

CONCLUSIONS

Human ASBT is induced by glucocorticoids in vitro and in vivo. Induction of ASBT by glucocorticoids could be beneficial in patients with Crohn's disease who exhibit reduced ASBT expression. This study identifies ASBT as a novel target of glucocorticoid controlled gene regulation in the human intestine.

Forced expression of dystrophin deletion constructs reveals structure-function correlations

Dystrophin plays an important role in skeletal muscle by linking the cytoskeleton and the extracellular matrix. The amino terminus of dystrophin binds to actin and possibly other components of the subsarcolemmal cytoskeleton, while the carboxy terminus associates with a group of integral and peripheral membrane proteins and glycoproteins that are collectively known as the dystrophin-associated protein (DAP) complex. We have generated transgenic/mdx mice expressing "full-length" dystrophin constructs, but with consecutive deletions within the COOH-terminal domains. These mice have enabled analysis of the interaction between dystrophin and members of the DAP complex and the effects that perturbing these associations have on the dystrophic process. Deletions within the cysteine-rich region disrupt the interaction between dystrophin and the DAP complex, leading to a severe dystrophic pathology. These deletions remove the beta-dystroglycan-binding site, which leads to a parallel loss of both beta-dystroglycan and the sarcoglycan complex from the sarcolemma. In contrast, deletion of the alternatively spliced domain and the extreme COOH terminus has no apparent effect on the function of dystrophin when expressed at normal levels. The proteins resulting from these latter two deletions supported formation of a completely normal DAP complex, and their expression was associated with normal muscle morphology in mdx mice. These data indicate that the cysteine-rich domain is critical for functional activity, presumably by mediating a direct interaction with beta-dystroglycan. However, the remainder of the COOH terminus is not required for assembly of the DAP complex.

Interaction of human Ku70 with TRF2

Ku, a heterodimer of 70- and 80-kDa subunits, plays a general role in the metabolism of DNA ends in eukaryotic cells, including double-strand DNA break repair, V(D)J recombination, and maintenance of telomeres. We have utilized the yeast two-hybrid system to identify Ku70-interacting proteins other than Ku80. Two reactive clones were found to encode the dimerization domain of TRF2, a mammalian telomeric protein that binds to duplex TTAGGG repeats at chromosome ends. This interaction was confirmed using bacterial fusion proteins and co-immunoprecipitations from eukaryotic cells overexpressing TRF2. The transfected TFR2 colocalized with Ku70.

Characterization of the human OATP-C (SLC21A6) gene promoter and regulation of liver-specific OATP genes by hepatocyte nuclear factor 1 alpha

OATP-C (SLC21A6) is the predominant Na(+)-independent uptake system for bile salts and bilirubin of human liver and is expressed exclusively at the basolateral (sinusoidal) hepatocyte membrane. To investigate the basis of liver-specific expression of OATP-C, we studied promoter function in the two hepatocyte-derived cell lines HepG2 and Huh7 and in nonhepatic HeLa cells. OATP-C promoter constructs containing from 66 to 950 nucleotides of 5'-regulatory sequence were active in HepG2 and Huh7 but not HeLa cells, indicating that determinants of hepatocyte-specific expression reside within the minimal promoter. Deoxyribonuclease I footprint analysis revealed a single region that was protected by HepG2 and Huh7 but not HeLa cell nuclear extracts. The liver-enriched transcription factor hepatocyte nuclear factor 1 alpha (HNF1 alpha) was shown by mobility shift assays to bind within this footprint. Coexpression of HNF1 alpha stimulated OATP-C promoter activity 30-fold in HepG2 and 49-fold in HeLa cells. Mutation of the HNF1 site abolished promoter function, indicating that HNF1 alpha is critical for hepatocyte-specific OATP-C gene expression. The human OATP8 (SLC21A8) and mouse Oatp4 (Slc21a6) promoters were also responsive to HNF1 alpha coexpression in HepG2 cells. These data support a role for HNF1 alpha as a global regulator of liver-specific bile salt and organic anion transporter genes.

Hydrothermal synthesis and magnetic behavior of a novel layered coordination polymer generated from manganese(II) adipate

A novel, two-dimensional organic/inorganic coordinate polymers, Mn2(H2O)[O2C(CH2)4CO2]2, was synthesized as single crystals by the hydrothermal reaction of MnCl2 with adipic acid in the presence of base and characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermal analysis, and SQUID magnetic measurement. It crystallized in the monoclinic space group C2/c(No. 15), with a = 21.671(2) A, b = 7.6023(7) A, c = 9.1452(9) A, beta = 108.849(7) A, Z = 4. The title compound presents a structure constituted by the stacking along [100] of MnO6 layers interleaved with adipate ions. The novel feature of the anionic layer is that it contains close-packed trans alkyl chains residing in an extended framework. Magnetization measurement shows this compound is antiferromagnetic below 15 K.

Single-dose pharmacokinetics of valganciclovir in HIV- and CMV-seropositive subjects

As a result of the low oral bioavailability of ganciclovir, a prodrug was developed to improve the bioavailability of ganciclovir. This study was designed to investigate the fasting, single-dose pharmacokinetics as well as the absolute and relative bioavailability of a valine ester prodrug of ganciclovir, valganciclovir, as compared to oral and intravenous ganciclovir in asymptomatic HIV+ and CMV+ subjects. In this open-label, randomized, three-period crossover study, 18 subjects received, in random order, single oral doses of valganciclovir 360 mg and ganciclovir 1000 mg and an intravenous infusion of ganciclovir 5 mg/kg over 1 hour. Valganciclovir was rapidly and extensively hydrolyzed to ganciclovir, resulting in significantly greater bioavailability compared to 1000 mg oral ganciclovir (60.9% vs. 5.6%, respectively). Higher peak serum concentrations were reached earlier following valganciclovir (ganciclovir [2.98 +/- 0.77 micrograms/mL at 1.0 +/- 0.3 h]) than following oral ganciclovir (0.47 +/- 0.17 microgram/mL and 2.2 +/- 1.0 h). Mean total ganciclovir AUCs following oral ganciclovir (1000 mg) and 360 mg valganciclovir (3.8 +/- 1.2 and 10.8 +/- 1.9 micrograms-h/mL) were less than that following a standard 5 mg/kg intravenous infusion of ganciclovir (25.1 +/- 3.8 micrograms-h/mL). In summary, valganciclovir is a prodrug with a favorable safety profile with enhanced bioavailability and significantly higher serum concentrations of ganciclovir than following oral administration of ganciclovir itself.

Radiation-pressure acceleration of ion beams driven by circularly polarized laser pulses

We present experimental studies on ion acceleration from ultrathin diamondlike carbon foils irradiated by ultrahigh contrast laser pulses of energy 0.7 J focused to peak intensities of 5x10(19) W/cm2. A reduction in electron heating is observed when the laser polarization is changed from linear to circular, leading to a pronounced peak in the fully ionized carbon spectrum at the optimum foil thickness of 5.3 nm. Two-dimensional particle-in-cell simulations reveal that those C6+ ions are for the first time dominantly accelerated in a phase-stable way by the laser radiation pressure.

Identification of alpha-syntrophin binding to syntrophin triplet, dystrophin, and utrophin

Syntrophin represents three cytoplasmic components of the dystrophin-glycoprotein complex that links the cytoskeleton to the extracellular matrix in skeletal muscle. alpha-Syntrophin has now been translated in vitro and shown to associate directly with all three components of the syntrophin triplet and with dystrophin. The in vitro translated 71-kDa non-muscle dystrophin isoform, containing the cystein-rich/C-terminal domain, can also interact with the syntrophin triplet. The syntrophin binding motif in dystrophin was localized to exons 73 and 74 including amino acids 3447-3481 by comparing the interactions of alpha-syntrophin and seven overlapping human dystrophin fusion proteins. More than one syntrophin interaction site in this binding motif was suggested. alpha-Syntrophin also interacts directly with a C-terminal utrophin fusion protein. alpha-Syntrophin is localized to the muscle sarcolemma as well as to the neuromuscular junction in control mouse muscle. However, similar to utrophin, alpha-syntrophin is only present at the neuromuscular junction in mdx mouse muscle in which dystrophin is absent. Our data suggest that alpha-syntrophin binds all syntrophin isoforms, and syntrophin directly interacts with dystrophin through more than one binding site in dystrophin exons 73 and 74 including amino acids 3447-3481.

Pharmacokinetics of ketorolac tromethamine in humans after intravenous, intramuscular and oral administration

The pharmacokinetics of ketorolac tromethamine, a potent non-narcotic analgesic agent used for relief of moderate to severe pain, has been studied in 15 healthy volunteers who received single 10 mg doses intravenously (i.v.), intramuscularly (i.m.) and orally (p.o.) in a three-way cross-over design. The kinetics of i.v. ketorolac were characterized by a terminal half-life of 5.09 h, a small plasma clearance (CL = 0.35 ml.min-1.kg-1) and a small tissue distribution (Vss = 0.11 l.kg-1, V beta = 0.17 l.kg-1; mean (SD). Following i.m. and p.o. administration, peak levels of approximately 0.8 microgram/ml were rapidly attained (tmax = 0.8 and 0.9 h, respectively) and the systemic bioavailability was essentially complete.

A systematic review of risk factors associated with near-fatal and fatal asthma

BACKGROUND

Asthma mortality and morbidity continue to be a serious global problem. Systematic reviews provide an opportunity to review risk factors in detail.

OBJECTIVE

To review all of the literature for risk factors associated with near-fatal asthma (NFA) and fatal asthma (FA).

METHODS

A literature search from 1960 to January 2004 in MEDLINE and EMBASE was conducted. Studies were included based on the following criteria: NFA was defined as an asthma exacerbation resulting in respiratory arrest requiring mechanical ventilation or a partial pressure of CO2 of at least 45 mmHg or asthma resulting in death (FA); the study reported the number of cases (NFA and/or FA) and asthmatic controls; there was explicit reporting of risk factors; cases that were adult and pediatric in nature; and all study types. Studies that included patients with chronic obstructive pulmonary disease were excluded.

RESULTS

Four hundred and three articles were identified, of which 27 met the inclusion criteria. Increased use of medications such as beta-agonists via metered dose inhalers (OR=1.67, 95% CI 0.99 to 2.84, P=0.057) and nebulizers (OR=2.45, 95% CI 1.52 to 3.93, P=0.0002), oral steroids (OR=2.71, 95% CI 1.34 to 5.51, P=0.006) and oral theophylline (OR=2.02, 95% CI 1.03 to 3.98, P=0.04) and a history of hospital (OR=2.62, 95% CI 1.04 to 6.58, P=0.04) and/or intensive care unit (OR=5.14, 95% CI 1.91 to 13.86, P=0.001) admissions and mechanical ventilation (OR=6.69, 95% CI 2.80 to 15.97, P=0.0001) due to asthma were predictors of NFA and FA. Prior emergency department assessment did not confer a greater risk of NFA and FA (OR=1.13, 95% CI 0.43 to 2.92, P=0.810). The use of inhaled corticosteroids (ICS) measured in a dose-independent fashion (did the patient take ICS previously; yes or no) inferred equivocal risk of NFA and FA (OR=1.31, 95% CI 0.83 to 2.05, P=0.25). However, two studies measured the use of ICS in a dose-dependent fashion (ie, measured the number of prescriptions filled within the previous six to 12 months). Both studies showed a trend toward a protective effect against FA. One study showed that the premature cessation of ICS can hasten death.

CONCLUSIONS

In the present study, risk factors of NFA and FA have been more accurately defined. Clinicians should identify patients with these characteristics to reduce their risk of NFA and FA. Further research should focus on quantifying the impact of risk factors on asthma deaths.

Pharmacokinetic, safety, and antiviral profiles of oral ganciclovir in persons infected with human immunodeficiency virus: a phase I/II study. AIDS Clinical Trials Group, and Cytomegalovirus Cooperative Study Group

A phase I/II study evaluated the pharmacokinetics, tolerability, and antiviral activity of oral ganciclovir in persons infected with human immunodeficiency virus (HIV). Oral bioavailability ranged from 2.6% to 7.3%. The mean maximum serum concentration achieved at 1000 mg every 8 h was 1.11 micrograms/mL, and mean trough level was 0.54 microgram/mL. The time to maximum serum drug concentration was 1.0-2.9 h, with a serum half-life of 3.0-7.3 h, suggesting prolonged oral absorption. Serious adverse events were uncommon. Decreased cytomegalovirus (CMV) shedding was observed from all sites. The median days (by dosage) to retinitis progression assessed by retinal examination after initiation of oral ganciclovir were 62 (1000 mg every 8 h), 148 (500 mg every 3 h), 75 (750 mg every 3 h), 148 (1000 mg every 3 h), and 139 (2000 mg every 8 h). Thus, oral ganciclovir has pharmacokinetic, toxicity, and antiviral profiles that may prove beneficial for both maintenance therapy of CMV retinitis and prevention of CMV disease in HIV-infected persons.

Characterization of delta-sarcoglycan, a novel component of the oligomeric sarcoglycan complex involved in limb-girdle muscular dystrophy

The sarcoglycan complex is known to be involved in limb-girdle muscular dystrophy (LGMD) and is composed of at least three proteins: alpha-, beta-, and gamma-sarcoglycan. delta-Sarcoglycan has now been identified as a second 35-kDa sarcolemmal transmembrane glycoprotein that shares high homology with gamma-sarcoglycan and is expressed mainly in skeletal and cardiac muscle. Biochemical analysis has demonstrated that gamma- and delta-sarcoglycan are separate entities within the sarcoglycan complex and that all four sarcoglycans exist in the complex on a stoichiometrically equal basis. Immunohistochemical analysis of skeletal muscle biopsies from patients with LGMD2C, LGMD2D, and LGMD2E demonstrated a reduction of the entire sarcoglycan complex in these muscular dystrophies. Furthermore, we have mapped the human delta-sarcoglycan gene to chromosome 5q33-q34 in a region overlapping the recently linked autosomal recessive LGMD2F locus.

Treatment of human immunodeficiency virus 1-infected infants and children with the protease inhibitor nelfinavir mesylate

An open-label study was conducted of nelfinavir mesylate, given with reverse transcriptase inhibitors to human immunodeficiency virus 1 (HIV-1)-infected infants and children 3 months to 13 years of age. Doses of nelfinavir mesylate of 20-30 mg/kg yielded drug exposures comparable to those seen in adults. The drug was well tolerated; mild diarrhea was the primary toxic effect observed. Seventy-one percent (39) of the 55 evaluable subjects had an initial decrease in plasma HIV-1 RNA, of at least 0.7 log10 copies/mL; suppression of plasma HIV-1 RNA levels to < 400 copies/mL was observed in 15. Children who began taking at least one new reverse transcriptase inhibitor near the time when nelfinavir mesylate was started, and those with a > or = 24% proportion of CD4 lymphocytes, had a greater chance of achieving and maintaining a decline in plasma HIV-1 RNA to < 400 copies/mL. Suppression of viremia was achieved in children as young as 3 months of age.

A biochemical, genetic, and clinical survey of autosomal recessive limb girdle muscular dystrophies in Turkey

Autosomal recessive limb girdle muscular dystrophy (LGMD2) is a clinically and genetically heterogenous group of diseases involving at least six different loci. Five genes have already been identified: calpain-3 at LGMD2A (15q15), and four members of the sarcoglycan (SG) complex, alpha-SG at LGMD2D (17q21), beta-SG at LGMD2E (4q12), gamma-SG at LGMD2C (13q12), and delta-SG at LGMD2F (5q33-q34). The gene product at LGMD2B (2p13-p16) is still unknown and at least one other gene is still unmapped. We investigated 20 Turkish families (18 consanguineous) diagnosed as having LGMD2. Most of our patients had onset of symptoms before age 10. The phenotypes varied from severe to benign. We analyzed the SG complex by immunofluorescence and/or western blot. Genotyping was performed using markers defining the six known loci and the suspected genes were screened for mutations. Six of 17 index cases showed deficiency of the SG complex, by immunofluorescence and/or western blot. Seven cases involved one of the known genes of the SG complex (alpha, 2; beta, 1; and gamma, 4 cases), and five mutations were documented in the alpha- and gamma-SG genes. After linkage analysis, 10 families were characterized as having LGMD2A (calpain-3 deficiency), and all mutations were eventually identified. One family was classified as having LGMD2B and 1 family that has normal SGs was linked to the chromosome 5q33-q34 locus (LGMD2F). In 1 family there was no linkage to any of the known LGMD2 loci. It appears that in Turkey, there is a broad spectrum of genes and defects involved in LGMD2. It may be possible to correlate genotype to phenotype in LGMD2. All severe cases belonged to the gamma-SG-deficiency group. Nine calpain-3-deficient cases had intermediate and 1 had moderate clinical courses. The LGMD2B patient had a moderate clinical expression, whereas the LGMD2F case was truly benign.

Bright laser-driven neutron source based on the relativistic transparency of solids

Neutrons are unique particles to probe samples in many fields of research ranging from biology to material sciences to engineering and security applications. Access to bright, pulsed sources is currently limited to large accelerator facilities and there has been a growing need for compact sources over the recent years. Short pulse laser driven neutron sources could be a compact and relatively cheap way to produce neutrons with energies in excess of 10 MeV. For more than a decade experiments have tried to obtain neutron numbers sufficient for applications. Our recent experiments demonstrated an ion acceleration mechanism based on the concept of relativistic transparency. Using this new mechanism, we produced an intense beam of high energy (up to 170 MeV) deuterons directed into a Be converter to produce a forward peaked neutron flux with a record yield, on the order of 10(10)  n/sr. We present results comparing the two acceleration mechanisms and the first short pulse laser generated neutron radiograph.

Ganciclovir absolute bioavailability and steady-state pharmacokinetics after oral administration of two 3000-mg/d dosing regimens in human immunodeficiency virus- and cytomegalovirus-seropositive patients

Oral ganciclovir has recently been approved for use in long-term maintenance therapy in the treatment of cytomegalovirus (CMV) retinitis in immunocompromised patients. Although oral ganciclovir at a dose of 3,000 mg/d is moderately less effective than intravenous (i.v.) ganciclovir maintenance therapy (5 mg/kg as a 1-hour i.v. infusion every 24 hours), convenience and practicality make oral maintenance therapy desirable. Two dosing regimens--1,000 mg three times daily (TID) and 500 mg every 3 hours (six times daily)--have been shown to be efficacious. Eighteen human immunodeficiency virus- and CMV-seropositive patients participated in a three-way, open-label, crossover study to evaluate the steady-state pharmacokinetics and absolute bioavailability of the two oral regimens compared with the i.v. regimen. Sixteen patients completed the study and received ganciclovir as a single 5-mg/kg i.v. infusion over 1 hour, 500 mg orally every 3 hours while awake (six times daily) for 3 days, and 1,000 mg TID orally for 3 days. Blood samples were obtained over a 24-hour period after the single i.v. dose and on day 3 of the oral dosing regimens. Mean peak serum concentrations were 8.27, 1.02, and 1.18 micrograms/mL for the i.v. and oral regimens, respectively. Twenty-four-hour area under the curve (AUC) for the oral regimens--500 mg every 3 hours and 1,000 mg TID--were 15.9 and 15.4 micrograms.h/mL, respectively, as compared with a total AUC of 22.1 micrograms.h/mL for the single i.v. dose. The absolute bioavailabilities for the two oral regimens were 8.84% and 8.53%, respectively. The extent of ganciclovir absorption, peak concentrations, and average concentration at steady state were not statistically different between the two oral regimens. The peak-to-trough concentration ratio (Cmax:Cmin) was greater for the 1,000-mg TID regimen than for the regimen of 500 mg every 3 hours (5.35 vs 3.81 [P < 0.01]). Both oral regimens resulted in concentrations in the range of the concentration that inhibits 50% of most human CMV isolates. Because both oral regimens provide equivalent absorption, the 1,000-mg TID regimen may be preferred for the convenience and potentially greater compliance associated with fewer daily doses.