The transcription factor 7-like 2 (TCF7L2) polymorphism may be associated with focal arteriolar narrowing in Caucasians with hypertension or without diabetes: the ARIC Study

Background

To investigate disease progression the first 12 months after diagnosis in children with type 1 diabetes negative (AAB negative) for pancreatic autoantibodies [islet cell autoantibodies(ICA), glutamic acid decarboxylase antibodies (GADA) and insulinoma-associated antigen-2 antibodies (IA-2A)]. Furthermore the study aimed at determining whether mutations in KCNJ11, ABCC8, HNF1A, HNF4A or INS are common in AAB negative diabetes.

Materials and methods

In 261 newly diagnosed children with type 1 diabetes, we measured residual β-cell function, ICA, GADA, and IA-2A at 1, 6 and 12 months after diagnosis. The genes KCNJ11, ABCC8, HNF1A, HNF4A and INS were sequenced in subjects AAB negative at diagnosis. We expressed recombinant K-ATP channels in Xenopus oocytes to analyse the functional effects of an ABCC8 mutation.

Results

Twenty-four patients (9.1%) tested AAB negative after one month. Patients, who were AAB-negative throughout the 12-month period, had higher residual β-cell function (P = 0.002), lower blood glucose (P = 0.004), received less insulin (P = 0.05) and had lower HbA_1c (P = 0.02) 12 months after diagnosis. One patient had a heterozygous mutation leading to the substitution of arginine at residue 1530 of SUR1 (ABCC8) by cysteine. Functional analyses of recombinant K-ATP channels showed that R1530C markedly reduced the sensitivity of the K-ATP channel to inhibition by MgATP. Morover, the channel was highly sensitive to sulphonylureas. However, there was no effect of sulfonylurea treatment after four weeks on 1.0-1.2 mg/kg/24 h glibenclamide.

Conclusion

GAD, IA-2A, and ICA negative children with new onset type 1 diabetes have slower disease progression as assessed by residual beta-cell function and improved glycemic control 12 months after diagnosis. One out of 24 had a mutation in ABCC8, suggesting that screening of ABCC8 should be considered in patients with AAB negative type 1 diabetes.     

Investigation into the Dissolution Rate Increase on Storage of Wellbutrin SR<Superscript>®</Superscript> 100 mg Tablets

The Food and Drug Administration (FDA) approved the New Drug Application for Wellbutrin sustained release (SR) 100 mg tablets on October 4, 1996. However, by 1998, the FDA expressed concern about the stability of this drug product based on an increase in the dissolution profile on storage. Data submitted in the annual report showed that this drug product could not meet the expiry of 18 months at the International Committee on Harmonization storage condition of 25°C/60% relative humidity. The FDA mandated a 12-month expiry and GlaxoWellcome tightened this further by instituting an expiry of 9 months. The FDA also requested a long-term solution to the stability of Wellbutrin SR 100 mg tablets. Investigations via colloidal solutions revealed that the dissolution rate increase on storage occurred due to acid hydrolysis of the release controlling polymer. This drug product was successfully reformulated by slowing the initial dissolution rate and having an increased ratio of release controlling polymer to acid stabilizer. The reformulation used the same ingredients and manufacturing unit processes as the original formulation. The reformulated drug product was approved by the FDA on October 11, 2000 with an 18-month shelf-life. The shelf-life was extended to 36 months in an annual update to the FDA on December 1, 2005.     

Reducing the Risk of Contamination of Sterile Parenteral Products via Ready-to-Use Closure Components

The preparation of sterile parenteral products requires careful control of all ingredients, materials, and processes to ensure the final product has the identity and strength, and meets the quality and purity characteristics that it purports to possess. Contamination affecting these critical properties of parenteral products can occur in many ways and from many sources. The use of closures supplied by manufacturers in a ready-to-use state can be an effective method for reducing the risk of contamination and improving the quality of the drug product. This article will address contamination attributable to elastomeric container closure components and the regulatory requirements associated with container closure systems. Possible contaminants, including microorganisms, endotoxins, and chemicals, along with the methods by which these contaminants can enter the product will be reviewed. Such methods include inappropriate material selection, improper closure preparation processes, compromised container closure integrity, degradation of closures, and leaching of compounds from the closures.     

Left ventricular hypertrophy is prevalent in Sprague-Dawley rats

Unrecognized cardiovascular abnormalities may confound the interpretation of research data collected using rats. However, although SPF rat colonies are screened for microbes and kept under standardized environmental conditions, their cardiovascular status is largely unknown. We recently performed surgery on anesthetized 80-d-old Sprague-Dawley rats and observed a high mortality that could not be attributed to the procedures or preceding treatments. Upon necropsy, cardiomyopathy was readily apparent in a substantial proportion of these rats. To further evaluate the nature of this condition, we evaluated the histology and morphology of hearts from both Sprague-Dawley and Lewis rats. Compared with Lewis rats, Sprague-Dawley rats had greater left ventricular wall thickness and larger cardiomyocyte cell size. Severe left ventricle hypertrophy was present in 38% of young adult Sprague-Dawley rats. These findings may have implications for research models that use Sprague-Dawley rats.     

HIV-1 Populations in Semen Arise through Multiple Mechanisms

HIV-1 is present in anatomical compartments and bodily fluids. Most transmissions occur through sexual acts, making virus in semen the proximal source in male donors. We find three distinct relationships in comparing viral RNA populations between blood and semen in men with chronic HIV-1 infection, and we propose that the viral populations in semen arise by multiple mechanisms including: direct import of virus, oligoclonal amplification within the seminal tract, or compartmentalization. In addition, we find significant enrichment of six out of nineteen cytokines and chemokines in semen of both HIV-infected and uninfected men, and another seven further enriched in infected individuals. The enrichment of cytokines involved in innate immunity in the seminal tract, complemented with chemokines in infected men, creates an environment conducive to T cell activation and viral replication. These studies define different relationships between virus in blood and semen that can significantly alter the composition of the viral population at the source that is most proximal to the transmitted virus.     

Inhibitors of RNA synthesis and passage of chick embryo fibroblasts through the G1 period

Events that are essential for progression through the G1 period begin immediately or shortly after resting chick embryo cells are given fresh medium with serum. The following observations support the contention that the critical events include the production of non-ribosomal RNAs: (1) Addition to the “shift-up” medium of either of two inhibitors of RNA formation, comptothecin or 5, 6-dichloro?1-β-D-ribofuranosylbenzimidazole, delays the onset of DNA replication by about the length of time the cells are exposed to the drugs. (2) Although entry into the S phase is delayed by the inhibitors, the slopes of the DNA response curves are identical to that of control cultures. (3) Neither drug reduces significantly the rate of overall protein synthesis. Observations (2) and (3) are taken to mean that expansion of the G1 period is not due to cell damage. (4) A third inhibitor of RNA synthesis, cordycepin, also delays passage of stimulated cells throgh the G1 phase, but, in this case, the length of the delay period is greater than that of the exposure period. (5) A low dose of actinomycin D does not impede movement towards the S phase, even though the synthesis of preribosomal RNA is considerably reduced. The possibility is considered that the essential G1 molecules are mRNAs.     

Naphthoquinone-lactones and extended quinones from Ventilago calyculata

New quinones have been isolated from the root bark of Ventilago calyculata. Ventilatones A and B are benzisochromanquinones, related to the ventiloquinones, which have an additional fused lactone ring while ventileins A and B are benzisochroman dimers having a dihydroxy-peri-xanthenoxanthenequinone chromophore.     

Benzisochromanquinones in ventilago species

From the acetone extract of the root bark of Ventilago maderaspatana eight new benzisochromanquinones; ventiloquinones A, B, C, D, E, F, G and H, have been isolated. Ventiloquinones I, J and K are three more new benzisochromanquinones isolated from the root bark of V. calyculata. The majority are 3,4,5,10-tetrahydro-cis-1,3-dimethyl-1H-naphtho[2,3-c]pyran-5,10-quinones related to eleutherin, but F, H, I, J and K are 6,9-quinones related to ventilagone.     

Force-induced bidirectional stepping of cytoplasmic dynein

Cytoplasmic dynein is a minus-end-directed microtubule motor whose mechanism of movement remains poorly understood. Here, we use optical tweezers to examine the force-dependent stepping behavior of yeast cytoplasmic dynein. We find that dynein primarily advances in 8 nm increments but takes other sized steps (4-24 nm) as well. An opposing force induces more frequent backward stepping by dynein, and the motor walks backward toward the microtubule plus end at loads above its stall force of 7 pN. Remarkably, in the absence of ATP, dynein steps processively along microtubules under an external load, with less force required for minus-end- than for plus-end-directed movement. This nucleotide-independent walking reveals that force alone can drive repetitive microtubule detachment-attachment cycles of dynein's motor domains. These results suggest a model for how dynein's two motor domains coordinate their activities during normal processive motility and provide new clues for understanding dynein-based motility in living cells.