A second genetic polymorphism in methylenetetrahydrofolate reductase (MTHFR) associated with decreased enzyme activity

A common mutation in methylenetetrahydrofolate reductase (MTHFR), C677T, results in a thermolabile variant with reduced activity. Homozygous mutant individuals (approximately 10% of North Americans) are predisposed to mild hyperhomocysteinemia, when their folate status is low. This genetic-nutrient interactive effect is believed to increase the risk for neural tube defects and vascular disease. In this communication, we characterize a second common variant in MTHFR (A1298C), an E to A substitution. Homozygosity was observed in approximately 10% of Canadian individuals. This polymorphism was associated with decreased enzyme activity; homozygotes had approximately 60% of control activity in lymphocytes. Heterozygotes for both the C677T and the A1298C mutation, approximately 15% of individuals, had 50-60% of control activity, a value that was lower than that seen in single heterozygotes for the C677T variant. No individuals were homozygous for both mutations. Additional studies of the A1298C mutation, in the absence and presence of the C677T mutation, are warranted, to adequately address the role of this new genetic variant in complex traits. A silent genetic variant, T1317C, was identified in the same exon. It was relatively infrequent (allele frequency 5%) in our study group, but was quite common in a small sample of African individuals (allele frequency 39%).

Olanzapine versus placebo and haloperidol: acute phase results of the North American double-blind olanzapine trial

Olanzapine is a potential new "atypical" antipsychotic agent. The double-blind acute phase of this study compared three dosage ranges of olanzapine (5 +/- 2.5 mg/day [Olz-L], 10 +/- 2.5 mg/day [Olz-M], 15 +/- 2.5 mg/day [Olz-H]) to a dosage range of haloperidol (15 +/- 5 mg/day [Hal]) and to placebo in the treatment of 335 patients who met the DSM-III-R criteria for schizophrenia. In overall symptomatology improvement (Brief Psychiatric Rating Scale [BPRS]-total), Olz-M, Olz-H, and Hal were significantly superior to placebo. In positive symptom improvement (BPRS-positive), Olz-M, Olz-H, and Hal were comparable and significantly superior to placebo. In negative symptom improvement (Scale for the Assessment of Negative Symptoms [SANS]-composite), Olz-L and Olz-H were significantly superior to placebo and Olz-H was also significantly superior to Hal. The most common treatment-emergent adverse events included somnolence, agitation, asthenia, and nervousness. No acute dystonia was observed with olanzapine. Treatment-emergent parkinsonism occurred with Olz-H at approximately one-third the rate of Hal, and akathisia occurred with Olz-H at approximately one-half the rate of Hal. Prolactin elevations associated with olanzapine were not significantly greater than those observed with placebo and were also significantly less than those seen with haloperidol.

Homodimer formation of retinoid X receptor induced by 9-cis retinoic acid

Retinoid response pathways are mediated by two classes of receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). A central question is whether distinct response pathways are regulated by these two classes of receptors. The observation that the stereoisomer 9-cis-retinoic acid binds with high affinity to RXRs suggested that this retinoid has a distinct role in controlling RXR activity, but it was almost simultaneously discovered that RXRs function as auxiliary receptors for RARs and related receptors, and are essential for DNA binding and function of those receptors. Hence, although RARs seem to operate effectively only as heterodimeric RAR/RXR complexes, RXRs themselves apparently function predominantly, if not exclusively, as auxiliary receptors. Here we report that 9-cis-retinoic acid induces RXR homodimer formation. Our results demonstrate a new mechanism for retinoid action by which a ligand-induced homodimer mediates a distinct retinoid response pathway.

A randomized controlled trial of duloxetine in diabetic peripheral neuropathic pain

BACKGROUND

Serotonin (5-HT) and norepinephrine (NE) are involved in pain modulation via descending inhibitory pathways in the brain and spinal cord.

OBJECTIVE

To assess the efficacy of duloxetine, a dual reuptake inhibitor of 5-HT and NE, on the reduction of pain severity, as well as secondary outcome measures in patients with diabetic peripheral neuropathic pain (DPNP).

METHODS

In this double-blind study, patients with DPNP and without comorbid depression were randomly assigned to treatment with duloxetine 60 mg once daily (QD), duloxetine 60 mg twice daily (BID), or placebo for 12 weeks. The primary outcome measure was the weekly mean score of 24-hour average pain severity on the 11-point Likert scale. Secondary measures and health outcome measures were also assessed.

RESULTS

Duloxetine 60 mg QD and 60 mg BID demonstrated improvement in the management of DPNP and showed rapid onset of action, with separation from placebo beginning at week 1 on the 24-hour average pain severity score. For all secondary measures for pain (except allodynia), mean changes showed an advantage of duloxetine over placebo, with no significant difference between 60 mg QD and 60 mg BID. Clinical Global Impression of Severity and Patient's Global Impression of Improvement evaluation demonstrated greater improvement on duloxetine- vs placebo-treated patients. Duloxetine showed no notable interference on diabetic controls, and both doses were safely administered.

CONCLUSIONS

This study confirms previous findings that duloxetine at 60 mg QD and 60 mg BID is effective and safe in the management of diabetic peripheral neuropathic pain.

The structure and properties of methylenetetrahydrofolate reductase from Escherichia coli suggest how folate ameliorates human hyperhomocysteinemia

Elevated plasma homocysteine levels are associated with increased risk for cardiovascular disease and neural tube defects in humans. Folate treatment decreases homocysteine levels and dramatically reduces the incidence of neural tube defects. The flavoprotein methylenetetrahydrofolate reductase (MTHFR) is a likely target for these actions of folate. The most common genetic cause of mildly elevated plasma homocysteine in humans is the MTHFR polymorphism A222V (base change C677-->T). The X-ray analysis of E. coli MTHFR, reported here, provides a model for the catalytic domain that is shared by all MTHFRs. This domain is a beta8alpha8 barrel that binds FAD in a novel fashion. Ala 177, corresponding to Ala 222 in human MTHFR, is near the bottom of the barrel and distant from the FAD. The mutation A177V does not affect Km or k(cat) but instead increases the propensity for bacterial MTHFR to lose its essential flavin cofactor. Folate derivatives protect wild-type and mutant E. coli enzymes against flavin loss, and protect human MTHFR and the A222V mutant against thermal inactivation, suggesting a mechanism by which folate treatment reduces homocysteine levels.

Olanzapine versus placebo: results of a double-blind, fixed-dose olanzapine trial

Olanzapine is a potential new "atypical" antipsychotic agent. This double-blind, acute phase study compared two doses of olanzapine [1 mg/day (Olz1.0); 10 mg/day (Olz10.0)] with placebo in the treatment of 152 patients who met the DSM-III-R criteria for schizophrenia and had a Brief Psychiatric Rating Scale (BPRS)-total score (items scored 0-6) > or = 24. In overall symptomatology improvement [BPRS-total score and Positive and Negative Syndrome Scale (PANSS)-total score], Olz10.0 was statistically significantly superior to placebo. In positive symptom improvement (PANSS-positive score, BPRS-positive score), Olz10.0 was statistically significantly superior to placebo. In negative symptom improvement (PANSS-negative score), Olz10.0 was statistically superior to placebo. Olz 1.0 was clinically comparable to placebo in all efficacy comparisons. The only adverse event to show an overall statistically significant incidence difference was anorexia (reported for 10% of placebo-treated and 0% of Olz10.0-treated patients). The Olz10.0-treated patients improved over baseline with respect to parkinsonian and akathisia symptoms, and these changes were comparable with those observed with placebo. There were no dystonias associated with Olz10.0 treatment. At endpoint, the incidence of patients with elevated prolactin values did not differ statistically significantly between placebo-treated and Olz10.0-treated patients. Olanzapine appears to be not only safe and effective, but a promising atypical antipsychotic candidate.

Genetic polymorphisms in methylenetetrahydrofolate reductase and methionine synthase, folate levels in red blood cells, and risk of neural tube defects

Folic acid administration to women in the periconceptional period reduces the occurrence of neural tube defects (NTDs) in their offspring. A polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR), 677C-->T, is the first genetic risk factor for NTDs in man identified at the molecular level. The gene encoding another folate-dependent enzyme, methionine synthase (MTR), has recently been cloned and a common variant, 2756A-->G, has been identified. We assessed genotypes and folate status in 56 patients with spina bifida, 62 mothers of patients, 97 children without NTDs (controls), and 90 mothers of controls, to determine the impact of these factors on NTD risk. Twenty percent of cases and 18% of case mothers were homozygous for the MTHFR polymorphism, compared to 11% of controls and 11% of control mothers, indicating that the mutant genotype conferred an increased risk for NTDs. The risk was further increased if both mother and child had this genotype. The MTR polymorphism was associated with a decreased O.R. (O.R.); none of the cases and only 10% of controls were homozygous for this variant. Red blood cell (RBC) folate was lower in cases and in case mothers, compared to their respective controls. Having a RBC folate in the lowest quartile of the control distribution was associated with an O.R. of 2.56 (95% CI 1.28-5.13) for being a case and of 3.05 (95% CI 1.54-6.03) for being a case mother. The combination of homozygous mutant MTHFR genotype and RBC folate in the lowest quartile conferred an O.R. for being a NTD case of 13.43 (CI 2.49-72.33) and an O.R. for having a child with NTD of 3.28 (CI 0.84-12.85). We propose that the genetic-nutrient interaction--MTHFR polymorphism and low folate status--is associated with a greater risk for NTDs than either variable alone.

Gene structure of human and mouse methylenetetrahydrofolate reductase (MTHFR)

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a co-substrate for homocysteine remethylation to methionine. A human cDNA for MTHFR, 2.2 kb in length, has been expressed and shown to result in a catalytically active enzyme of approximately 70 kDa. Fifteen mutations have been identified in the MTHFR gene: 14 rare mutations associated with severe enzymatic deficiency and 1 common variant associated with a milder deficiency. The common polymorphism has been implicated in three multifactorial diseases: occlusive vascular disease, neural tube defects, and colon cancer. The human gene has been mapped to chromosomal region 1p36.3 while the mouse gene has been localized to distal Chromosome (Chr) 4. Here we report the isolation and characterization of the human and mouse genes for MTHFR. A human genomic clone (17 kb) was found to contain the entire cDNA sequence of 2.2 kb; there were 11 exons ranging in size from 102 bp to 432 bp. Intron sizes ranged from 250 bp to 1.5 kb with one exception of 4.2 kb. The mouse genomic clones (19 kb) start 7 kb 5' exon 1 and extend to the end of the coding sequence. The mouse amino acid sequence is approximately 90% identical to the corresponding human sequence. The exon sizes, locations of intronic boundaries, and intron sizes are also quite similar between the two species. The availability of human genomic clones has been useful in designing primers for exon amplification and mutation detection. The mouse genomic clones will be helpful in designing constructs for gene targeting and generation of mouse models for MTHFR deficiency.

A double-blind, randomized comparison of the efficacy and safety of intramuscular injections of olanzapine, lorazepam, or placebo in treating acutely agitated patients diagnosed with bipolar mania

There are no rapid-acting intramuscular formulations of atypical antipsychotics available for quickly calming an agitated patient with bipolar disorder. In this study, 201 agitated patients with bipolar mania were randomly assigned to receive one to three injections of the atypical antipsychotic olanzapine (10 mg, first two injections; 5 mg, third injection), the benzodiazepine lorazepam (2 mg, first two injections; 1 mg, third injection), or placebo (placebo, first two injections; olanzapine, 10 mg, third injection) within a 24-hour period. Agitation was measured at baseline, every 30 minutes for the first 2 hours, and at 24 hours after the first injection using the Positive and Negative Syndrome Scale-Excited Component subscale and two additional agitation scales. At 2 hours after the first injection, patients treated with olanzapine showed a significantly greater reduction in scores on all agitation scales compared with patients treated with either placebo or lorazepam. At 24 hours after the first injection, olanzapine remained statistically superior to placebo in reducing agitation in patients with acute mania, whereas patients treated with lorazepam were not significantly different from those treated with placebo or olanzapine. Furthermore, no significant differences among the three treatment groups were observed in safety measures, including treatment-emergent extrapyramidal symptoms, the incidence of acute dystonia, or QTc interval changes. These findings suggest that intramuscular olanzapine is a safe and effective treatment for reducing acute agitation in patients with bipolar mania.

First-line nivolumab plus ipilimumab with two cycles of chemotherapy versus chemotherapy alone (four cycles) in advanced non-small-cell lung cancer: CheckMate 9LA 2-year update

BACKGROUND

To further characterize survival benefit with first-line nivolumab plus ipilimumab with two cycles of chemotherapy versus chemotherapy alone, we report updated data from the phase III CheckMate 9LA trial with a 2-year minimum follow-up.

PATIENTS AND METHODS

Adult patients were treatment naïve, with stage IV/recurrent non-small-cell lung cancer, no known sensitizing EGFR/ALK alterations, and an Eastern Cooperative Oncology Group performance status ≤1. Patients were randomized 1 : 1 to nivolumab 360 mg every 3 weeks plus ipilimumab 1 mg/kg every 6 weeks with two cycles of chemotherapy, or four cycles of chemotherapy. Updated efficacy and safety outcomes are reported, along with progression-free survival (PFS) after next line of treatment (PFS2), treatment-related adverse events (TRAEs) by treatment cycle, and efficacy outcomes in patients who discontinued all treatment components in the experimental arm due to TRAEs.

RESULTS

With a median follow-up of 30.7 months, nivolumab plus ipilimumab with chemotherapy continued to prolong overall survival (OS) versus chemotherapy. Median OS was 15.8 versus 11.0 months [hazard ratio 0.72 (95% confidence interval 0.61-0.86)]; 2-year OS rate was 38% versus 26%. Two-year PFS rate was 20% versus 8%. ORR was 38% versus 25%, respectively; 34% versus 12% of all responses were ongoing at 2 years. Median PFS2 was 13.9 versus 8.7 months. Improved efficacy outcomes in the experimental versus control arm were observed across most subgroups, including by programmed death-ligand 1 and histology. No new safety signals were observed; onset of grade 3/4 TRAEs was mostly observed during the first two treatment cycles in the experimental arm. In patients who discontinued all components of nivolumab plus ipilimumab with chemotherapy treatment due to TRAEs (n = 61) median OS was 27.5 months; 56% of responders had an ongoing response ≥1 year after discontinuation.

CONCLUSIONS

With a 2-year minimum follow-up, nivolumab plus ipilimumab with two cycles of chemotherapy provided durable efficacy benefits over chemotherapy with a manageable safety profile and remains an efficacious first-line treatment of advanced non-small-cell lung cancer.

Charge transport along the lambda-DNA double helix

We have measured the conductivity sigma along the lambda phage DNA (lambda-DNA) double helix at microwave frequencies using lyophilized DNA in and also without a buffer. The conductivity is strongly temperature dependent around room temperature with a crossover to a weakly temperature dependent conductivity at low temperatures. Removal of the water mantle around the double helix leads to reduced conductivity.

Genomic cloning of methylthioadenosine phosphorylase: a purine metabolic enzyme deficient in multiple different cancers

5'-Deoxy-5'-methylthioadenosine phosphorylase (methylthioadeno-sine: ortho-phosphate methylthioribosyltransferase, EC 24.2.28; MTAP) plays a role in purine and polyamine metabolism and in the regulation of transmethylation reactions. MTAP is abundant in normal cells but is deficient in many cancers. Recently, the genes for the cyclin-dependent kinase inhibitors p16 and p15 have been localized to the short arm of human chromosome 9 at band p21, where MTAP and interferon alpha genes (IFNA) also map. Homozygous deletions of p16 and p15 are frequent malignant cell lines. However, the order of the MTAP, p16, p15, and IFNA genes on chromosome 9p is uncertain, and the molecular basis for MTAP deficiency in cancer is unknown. We have cloned the MTAP gene, and have constructed a topologic map of the 9p21 region using yeast artificial chromosome clones, pulse-field gel electrophoresis, and sequence-tagged-site PCR. The MTAP gene consists of eight exons and seven introns. Of 23 malignant cell lines deficient in MTAP protein, all but one had complete or partial deletions. Partial or total deletions of the MTAP gene were found in primary T-cell acute lymphoblastic leukemias (T-ALL). A deletion breakpoint of partial deletions found in cell lines and primary T-ALL was in intron 4. Starting from the centromeric end, the gene order on chromosome 9p2l is p15, p16, MTAP, IFNA, and interferon beta gene (IFNB). These results indicate that MTAP deficiency in cancer is primarily due to codeletion of the MTAP and p16 genes.

COUP orphan receptors are negative regulators of retinoic acid response pathways

The vitamin hormone retinoic acid (RA) regulates many complex biological programs. The hormonal signals are mediated at the level of transcription by multiple nuclear receptors. These receptors belong to the steroid/thyroid hormone receptor superfamily that also includes a large number of orphan receptors whose biological roles have not yet been determined. Although much has been learned in recent years about RA receptor (RAR) functions, little is known about how specific RA response programs are restricted to certain tissues and cell types during development and in the adult. It has been recently shown that RAR activities are regulated by retinoid X receptors (RXR) through heterodimer formation. In an effort to isolate and further characterize nuclear receptors that modulate RAR and/or RXR activities, we have screened cDNA libraries by using a RXR alpha cDNA probe. Two clones, COUP alpha and COUP beta, identical and closely related to the orphan receptor COUP-TF, were obtained. We show that COUP proteins dramatically inhibit retinoid receptor activities on certain response elements that are activated by RAR/RXR heterodimers or RXR homodimers. COUP alpha and -beta bind strongly to these response elements, including a palindromic thyroid hormone response element and a direct repeat RA response element as well as an RXR-specific response element. In addition, we found that the previously identified COUP-TF binding site in the ovalbumin gene functions in vitro as an RA response element that is repressed in the presence of COUP. Our data suggest that the COUP receptors are a novel class of RAR and RXR regulators that can restrict RA signaling to certain elements. The COUP orphan receptors may thus play an important role in cell- or tissue-specific repression of subsets of RA-sensitive programs during development and in the adult.

How electrolyte shielding influences the electrical potential in transmembrane ion channels

The electrical potential due to fixed charge distributions is strongly altered in the vicinity of a membrane and notably dependent on aqueous electrolyte concentration. We present an efficient way to solve the nonlinear Poisson-Boltzmann equation applicable to general cylindrically symmetric dielectric geometries. It generalizes Gouy-Chapman theory to systems containing transmembrane channels. The method is applied to three channel systems: gramicidin, gap junction, and porin. We find that for a long, narrow channel such as gramicidin concentration variation has little influence on the electrical image barrier to ion permeation. However, electrolyte shielding reduces the image induced contribution to the energy required for multiple occupancy. In addition, the presence of electrolyte significantly affects the voltage profile due to an applied potential, substantially compressing the electric field to the immediate vicinity of the pore itself. In the large diameter channels, where bulk electrolyte may be assumed to enter the pore, the electrolyte greatly reduces the image barrier to ion permeation. At physiological ionic strengths this barrier is negligible and the channel may be readily multiply occupied. At all ionic strengths considered (l greater than 0.005 M) the image barrier saturates rapidly and is essentially constant more than one channel radius from the entrance to the pore. At lower ionic strengths (l less than 0.016 M) there are noticeable (greater than 20 mV) energy penalties associated with multiple occupancy.

Polarized light microscopy and digital image processing identify a multilaminar structure of the hamster zona pellucida

The zona pellucida (zona) is a glycoprotein coat that envelopes the oocyte and embryo, binds sperm during fertilization and facilitates transfer of the embryo through the Fallopian tube. Before implantation can occur, the blastocyst must hatch from the zona. Several lines of evidence suggest that the zona is multilaminar. We hypothesized that the multilaminar structure of the zona filaments could be imaged non-destructively with the polarized light microscope. A recent modification of the polarized light microscope (pol-scope), which combines innovations in polarization optics with novel image processing software, allows measurement of birefringence at all points of the image. Hamster metaphase II oocytes were placed on glass coverslips which replaced the bottom of culture dishes, imaged under differential interference contrast (DIC) and pol-scope optics, then digitized and processed to measure birefringence magnitude and orientation. The pol-scope revealed the zona to be divided into outer and inner layers separated by a zone of low retardance. This finding is consistent with filaments in the outer layer oriented tangentially and in the inner layer oriented radially. The multilaminar structure of the mammalian zona suggested by differential lectin binding and by scanning electron microscopy could be imaged non-destructively with the pol-scope. Because the pol-scope provides a non-destructive method to identify macro-molecular organization of the zona, it may prove useful in developmental studies of hatching and to direct resection of the zona.

Hunger in legal immigrants in California, Texas, and Illinois

OBJECTIVES

This study determined the prevalence of food insecurity and hunger in low-income legal immigrants.

METHODS

We conducted a cross-sectional survey of Latino and Asian legal immigrants attending urban clinics and community centers in California, Texas, and Illinois with a food security questionnaire.

RESULTS

Among 630 respondents, 40% of the households were food insecure without hunger and 41% were food insecure with hunger. Independent predictors of hunger were income below federal poverty level (odds ratio [OR] = 2.72, 95% confidence interval [CI] = 1.72, 4.30), receipt of food stamps (OR = 2.53, 95% CI = 1.57, 4.09), Latino ethnicity (OR = 2.39, 95% CI = 1.49, 3.82), and poor English (OR = 1.76, 95% CI = 1.10, 2.82).

CONCLUSIONS

The prevalence of hunger among low-income legal immigrants is unacceptably high. Access to food assistance programs is important for the health and well-being of this population.

Synovasure 'quick test' is not as accurate as the laboratory-based α-defensin immunoassay: a systematic review and meta-analysis

AIMS

α-defensin is a biomarker which has been described as having a high degree of accuracy in the diagnosis of periprosthetic joint infection (PJI). Current meta-analyses are based on the α-defensin laboratory-based immunoassay rather than the quick on-table lateral flow test kit. This study is the first meta-analysis to compare the accuracy of the α-defensin laboratory-based immunoassay and the lateral flow test kit for the diagnosis of PJI.

MATERIALS AND METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Inclusion criteria were all clinical studies where the diagnosis of PJI was uncertain. All studies selected used the Musculoskeletal Infection Society (MSIS) or modified MSIS criteria. Two independent reviewers reviewed the studies and extracted data. A meta-analysis of results was carried out: pooled sensitivity, specificity, positive and negative likelihood ratio, heterogeneity and areas under curves are reported.

RESULTS

Ten studies (759 patients) were included. Of these, seven studies (640 patients) evaluated the laboratory-based α-defensin immunoassay and three (119 patients) the lateral flow test. The pooled sensitivity and specificity of the qualitative α-defensin laboratory immunoassay was 0.953 (95% confidence interval (CI) 0.87 to 0.984) and 0.965 (95% CI 0.943 to 0.979) respectively. The pooled positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 34.86 (95% CI 19.34 to 62.85) and 0.02 (95% CI 0.00 to 0.11). The pooled sensitivity and specificity of the lateral flow test were 0.774 (95% CI 0.637 to 0.870) and 0.913 (95% CI 0.828 to 0.958), respectively. The pooled PLR and NLR were 8.675 (95% CI 4.229 to 17.794) and 0.248 (95% CI 0.147 to 0.418), respectively.

CONCLUSION

The pooled sensitivity and specificity of the lateral flow test were lower than those of the α-defensin laboratory-based immunoassay test. Hence, care must be taken with interpretation of the lateral flow test when relying on its results for the intra-operative diagnosis of PJI. Cite this article: Bone Joint J 2018;100-B:66-72.

Age-associated NF-κB signaling in myofibers alters the satellite cell niche and re-strains muscle stem cell function

Skeletal muscle is a highly regenerative tissue, but muscle repair potential is increasingly compromised with advancing age. In this study, we demonstrate that increased NF-κB activity in aged muscle fibers contributes to diminished myogenic potential of their associated satellite cells. We further examine the impact of genetic modulation of NF-κB signaling in muscle satellite cells or myofibers on recovery after damage. These studies reveal that NF-κB activity in differentiated myofibers is sufficient to drive dysfunction of muscle regenerative cells via cell-non-autonomous mechanisms. Inhibition of NF-κB, or its downstream target Phospholipase A2, in myofibers rescued muscle regenerative potential in aged muscle. Moreover, systemic administration of sodium salicylate, an FDA-approved NF-κB inhibitor, decreased inflammatory gene expression and improved repair in aged muscle. Together, these studies identify a unique NF-κB regulated, non-cell autonomous mechanism by which stem cell function is linked to lipid signaling and homeostasis, and provide important new targets to stimulate muscle repair in aged individuals.

Long-term supplementation with a cystine-based antioxidant delays loss of muscle mass in aging

Oxidative stress increases with age and is postulated to be a major causal factor for sarcopenia in aging. Here, we examined whether the administration of a cystine-based antioxidant (F1) can alleviate/delay age-specific changes in skeletal muscles. C57BL6 male mice aged 17 months (middle aged) were fed with normal diet with or without supplementation of F1 (3 mg/kg food) for 6 months. Compared with young (5 months old) mice old mice exhibited increased markers of oxidative stress, inflammation, and muscle cell apoptosis and decreased muscle weight. These age-related changes were further associated with inactivation of adenosine-5'-monophosphate-activated protein kinase (AMPK), increased lipogenesis, activation of c-Jun NH2-terminal kinase, and decreased expression of Delta 1, phospho-Akt, and proliferating cell nuclear antigen in aged skeletal muscle. Such alterations were significantly prevented by F1. These results demonstrate the beneficial effects of F1 to attenuate loss of muscle mass associated with aging.

Standard olanzapine versus placebo and ineffective-dose olanzapine in the maintenance treatment of schizophrenia

OBJECTIVE

Two studies compared the efficacy of standard-dose oral olanzapine (5 to 15 mg a day) with placebo and with ineffective-dose olanzapine (1 mg a day) in maintenance therapy of schizophrenia.

METHODS

The studies were 46-week double-blind extensions of multicenter studies that assessed the efficacy of olanzapine in the acute treatment of schizophrenia. Subjects were 120 adults who met DSM-III-R criteria for schizophrenia with an acute exacerbation and who had a minimum score of 24 on the Brief Psychiatric Rating Scale, who had responded to acute therapy (defined as at least a 40 percent reduction in the BPRS score from baseline or a score of 18 or less during up to six weeks of treatment), and who were outpatients at their last acute-phase visit. Relapse was defined as hospitalization for psychopathology. Relapse risk was analyzed using Kaplan-Meier survival analysis and life table analysis. Patients who relapsed were discontinued from the studies.

RESULTS

In the first study (N = 58), patients in the standard-dose olanzapine group experienced a significantly lower relapse risk (p = .002) over one year than patients treated with placebo. The estimated one-year risk of relapse with olanzapine was 28.6 percent, compared with 69.9 percent with placebo. Results were similar in the second study (N = 62); patients treated with standard-dose olanzapine had a significantly reduced risk of relapse (p = .018) over one year compared with patients treated with ineffective-dose olanzapine. The estimated one-year risks of relapse were 19.6 percent for standard-dose olanzapine and 45.5 percent for ineffective-dose olanzapine.

CONCLUSIONS

Olanzapine is superior to placebo and ineffective-dose olanzapine in the maintenance therapy of schizophrenia.

Trained nurses can provide safe and effective sedation for MRI in pediatric patients

PURPOSE

To determine the success rate, safety and complications using a standard protocol and trained nurses to provide sedation for MRI under the supervision of a radiologist.

MATERIALS AND METHODS

Nurses were trained to provide sedation via a standard protocol for pediatric patients undergoing diagnostic MRI. Oral chloral hydrate (80-100 mg x kg(-1)) was used for children less than 18 mo of age. Older children received either 1-6 mg x kg(-1) pentobarbital i.v., with or without 1-2 microg x kg x hr(-1) fentanyl, or 25 mg x kg(-1) thiopental pr. Sedation was defined as successful if it allowed completion of the MRI without image distorting patient movement. The records of 572 MRIs performed on 488 pediatric patients (mean age 5+/-4 yr; age 2 mo-14 yr) from 1991 to July 1995 were reviewed to determine the success rate and complications using the sedation program.

RESULTS

Most, 91.8% (525/572), of the MRIs were successfully completed in 445 patients. The reasons for failure were inadequate sedation (45, 95.7%) and coughing (2, 4.2%). The failure rate was much higher before 1994 (38/272, 14%) than after (9/300, 3%; P<0.0001). Failure was more common if rectal thiopental was used (23/172, 14%) than intravenous pentobarbital (19/256, 7.4%; P<0.05). The failure rate was also high in patients with a history of a behavioural disorder (10/59, 17%). There were no deaths or unexpected admissions as a result of the sedation program.

CONCLUSION

A high success rate can be achieved as experience is gained using a standard protocol and trained nurses to sedate children for MRI.

Retinoic acid receptors and retinoid X receptor-alpha down-regulate the transforming growth factor-beta 1 promoter by antagonizing AP-1 activity

Overexpression of the multifunctional growth factor transforming growth factor-beta 1 (TGF beta 1) has been connected to numerous diseases in human. TGF beta 1 expression is largely governed by three AP-1 binding sites located in two different promoters of this gene. We have examined the ability of retinoid receptors to inhibit the activity of the two promoters (especially the promoter 1) by cotransfection assays in the hepatocellular carcinoma cell line HepG2. When the TGF beta 1 promoter activity is induced by 12-O-tetradecanoyl phorbol13-acetate (an activator of AP-1-controlled gene transcription), this activity can be strongly repressed by retinoic acid receptor-alpha (RAR alpha), RAR beta, or retinoid X receptor-alpha (RXR alpha) as well as other members of the nuclear receptor family. Repression was hormone dependent and a function of receptor concentration. Heterodimerization of RAR alpha or RAR beta with RXR alpha did not modify the inhibition activities of these receptors, indicating that heterodimer formation is not required for antagonizing of AP-1 activity. On further examining the anti-AP-1 activity of RXR alpha we observed that three different AP-1-controlled promoters (TGF beta 1, collagenase, and cFos) can be inhibited. Using gel shift assays, we demonstrated that RXR alpha inhibits Jun and Fos DNA binding and that 9-cis RA enhances this inhibition, suggesting that a mechanism involving direct protein-protein interaction between RXR and AP-1 components mediates the inhibitory effect observed in vivo. Transfection analyses with RXR alpha point mutations revealed that residues L422, C432, and, to a lesser extent, residues L418 and L430, are involved in ligand-induced anti-AP1 activity of RXR alpha in vivo. Thus both types of retinoid receptors can inhibit AP-1-activated promoters, including the TGF beta 1 gene promoter, via a mechanism that involves protein-protein interaction.

Retinoic acid receptors and retinoid X receptor-alpha down-regulate the transforming growth factor-beta 1 promoter by antagonizing AP-1 activity

Overexpression of the multifunctional growth factor transforming growth factor-beta 1 (TGF beta 1) has been connected to numerous diseases in human. TGF beta 1 expression is largely governed by three AP-1 binding sites located in two different promoters of this gene. We have examined the ability of retinoid receptors to inhibit the activity of the two promoters (especially the promoter 1) by cotransfection assays in the hepatocellular carcinoma cell line HepG2. When the TGF beta 1 promoter activity is induced by 12-O-tetradecanoyl phorbol13-acetate (an activator of AP-1-controlled gene transcription), this activity can be strongly repressed by retinoic acid receptor-alpha (RAR alpha), RAR beta, or retinoid X receptor-alpha (RXR alpha) as well as other members of the nuclear receptor family. Repression was hormone dependent and a function of receptor concentration. Heterodimerization of RAR alpha or RAR beta with RXR alpha did not modify the inhibition activities of these receptors, indicating that heterodimer formation is not required for antagonizing of AP-1 activity. On further examining the anti-AP-1 activity of RXR alpha we observed that three different AP-1-controlled promoters (TGF beta 1, collagenase, and cFos) can be inhibited. Using gel shift assays, we demonstrated that RXR alpha inhibits Jun and Fos DNA binding and that 9-cis RA enhances this inhibition, suggesting that a mechanism involving direct protein-protein interaction between RXR and AP-1 components mediates the inhibitory effect observed in vivo. Transfection analyses with RXR alpha point mutations revealed that residues L422, C432, and, to a lesser extent, residues L418 and L430, are involved in ligand-induced anti-AP1 activity of RXR alpha in vivo. Thus both types of retinoid receptors can inhibit AP-1-activated promoters, including the TGF beta 1 gene promoter, via a mechanism that involves protein-protein interaction.