PTP1B inhibitors: synthesis and evaluation of difluoro-methylenephosphonate bioisosteres on a sulfonamide scaffold

We have synthesized and evaluated a series of triaryl sulfonamide-based PTP1B inhibitors in which a difluoro-methylenephosphonate group of a potent lead has been replaced by potential bioisosteric replacements. Several mono- or di-charged compounds (8a, 8b, and 15a) were shown exhibit inhibitory activity in the low micromolar range, demonstrating the feasibility of using this approach in identifying non-phosphonate pTyr mimetics in a small molecular scaffold. These results also provide a useful indication of the relative effectiveness of these pTyr mimetics.     

Stimulation of the Streptococcus pneumoniae RecA protein-promoted three-strand exchange reaction by the competence-specific SsbB protein

The effect of the transformational competence-specific Streptococcus pneumoniae single-stranded DNA binding protein, SpSsbB, on the ATP-dependent three-strand exchange activity of the SpRecA protein was investigated. Although SpRecA exhibited only a trace level of strand exchange activity in the absence of SpSsbB, an extensive strand exchange reaction was observed when SpSsbB was added to the reaction solution after SpRecA. A more limited strand exchange reaction was observed, however, when SpSsbB was added to the reaction solution before SpRecA. This dependence on the order of addition, together with additional DNA-dependent ATP hydrolysis experiments, indicated that the mechanism of stimulation may involve the postsynaptic binding of SpSsbB to the displaced linear single-stranded DNA reaction product. When dATP was provided in place of ATP as the nucleotide cofactor (to suppress a potentially inhibitory effect of SpSsbB on the interaction of SpRecA with the circular ssDNA reaction substrate), the stimulatory effect of SpSsbB on the strand exchange reaction was apparent regardless of the order in which it was added to the reaction solution. These findings suggest that SpSsbB may be able to facilitate SpRecA-promoted DNA recombination reactions during natural transformation in S. pneumoniae.     

Metal Binding at the Deinococcus radiodurans Dps-1 N-Terminal Metal Site Controls Dodecameric Assembly and DNA Binding

The prokaryotic DNA protection during starvation (Dps) proteins typically protect macromolecules against damaging agents via physical association with DNA and by oxidizing and sequestering iron. However, Deinococcus radiodurans Dps-1, which binds DNA with high affinity, fails to protect DNA against hydroxyl radicals due to iron leakage from the core, raising the question of how (?)OH-mediated damage to Dps-1-bound DNA is avoided. As shown here, Mn(II) inhibits ferroxidase activity, suggesting that ferroxidation may be prevented in vivo as D. radiodurans accumulates a high ratio of Mn:Fe. Dps-1 has an N-terminal extension with a unique metal-binding site, an extension that has been proposed to be important for DNA binding and dodecameric assembly. Electrophoretic mobility shift assays show that Mn(II) restores DNA binding to bipyridyl-treated Dps-1, whereas Fe(II) fails to do so in the presence of H(2)O(2), thus preventing DNA binding under conditions of ongoing ferroxidase activity. We also show that disruption of the N-terminal metal site leads to a significant reduction in DNA binding and to compromised oligomeric assembly, with the mutant protein assembling into a hexamer in the presence of divalent metal. We propose that securing the N-terminal loop by metal binding is required to initiate dodecameric assembly by contacting the neighboring dimer and that the absence of such optimal contacts results in formation of a hexameric assembly intermediate in which three dimers associate about one of the 3-fold axes. Once dodecameric Dps-1 is assembled, metal binding no longer affects oligomeric state; instead, differential metal binding controls DNA interaction under conditions of oxidative stress.     

Measuring health state preferences in women with breast hypertrophy

The purpose of this article is to introduce the measurement of utilities, or patient preferences, to the plastic surgery community. Specifically, the study demonstrated the development and validation of a utility measure for estimating the health-related quality of life in women with breast hypertrophy. Two self-administered instruments were developed, a Wheel and a Table. All subjects completed the utility assessments for their "current health" and again for "breast-related symptoms." The reliability of the instruments was assessed in repeat (test-retest) interviews of 47 women within 10 to 18 days. Utilities obtained with the new instruments were also compared with the performance of other validated utility assessment instruments, including a visual analogue scale, a computer-based instrument (U-Titer), and a preference classification system (EuroQol). Of the 47 women in the test-retest reliability study, 21 had experienced breast hypertrophy (13 had not had reduction surgery and 8 had undergone reduction mammaplasty). Mean utility values for breast-related symptoms among women with breast hypertrophy (n = 13) were: Table, 0.85; Wheel, 0.90; and U-Titer, 0.66. Current health utility scores were significantly lower for women with breast hypertrophy (n = 13), as measured by all instruments except the Wheel. The Table had good reliability and distinguished women with breast hypertrophy from those without. Although the Table provided higher utility values for the same health state compared with the computer-based interview (U-Titer), it is much less costly to implement. The Table is recommended as a reasonable alternative for use in multicenter studies of women with breast hypertrophy. The reported utility value for breast hypertrophy of 0.86 is much lower than predicted. It is comparable with the reported burden of living with other health conditions, such as moderate angina (0.90) and a kidney transplant (0.84).     

Effect on prostatic growth of 2-difluoromethylornithine, an effective inhibitor of ornithine decarboxylase.

2-Difluoromethylornithine (DFMO), an enzyme-activated irreversible inhibitor of ornithine decarboxylase, causes marked changes in the polyamine metabolism of ventral prostate when given to adult rats in drinking water (20 g/l) for 3 consecutive days. A 90% inhibition of ornithine decarboxylase activity is accompanied by approx. 80% decreases of the concentrations of putrescine and spermidine and by a 36% decrease in spermine. Concomitantly, S-adenosylmethionine decarboxylase activity increases 7-fold and the concentration of decarboxylated S-adenosylmethionine 450-fold. When DFMO is given to immature rats for 12 consecutive days the above described changes are accompanied by a marked reduction in the age-dependent increases of the wet weight and RNA and DNA contents of the ventral prostate. In adult rats DFMO decreases the weight and RNA content of the ventral prostate within 4 days by 32% and 24% respectively and maintains them constant for the next 19 days. After 23 days of treatment, the prostatic weight is 46% of that of control animals of the same age, whereas the weights of other organs are only slightly decreased. Cytological studies carried out at this time show that DFMO reduces the size of both prostatic acini and the epithelial cells lining the acini.     

New materials from proteins and peptides

In this review we highlight recent accomplishments in the design of materials from proteins and peptides. Examples include hydrogels made from aggregating designed β-hairpin peptides, whose physical properties respond to small changes in the amino acid composition of the peptide; materials that combine different segments of natural elastomeric proteins - such as elastin, resilin, silk fibroin whose bulk properties are dictated in unanticipated ways by their composition; and hydrogels formed by strings or arrays of protein modules, which are cross-linked by multivalent versions of their peptide ligands, and which may exhibit exquisite stimuli-responsive behavior. The suitability of the unique properties of such new materials for practical applications is also considered.     

(-)-Epigallocatechin-3-gallate Inhibits Pancreatic Lipase and Reduces Body Weight Gain in High Fat-Fed Obese Mice

Tea (Camellia sinensis, Theaceae) has been shown to have obesity preventive effects in laboratory studies. We hypothesized that dietary epigallocatechin‐3‐gallate (EGCG) could reverse metabolic syndrome in high fat‐fed obese C57bl/6J mice, and that these effects were related to inhibition of pancreatic lipase (PL). Following treatment with 0.32% EGCG for 6 weeks, a 44% decrease in body weight (BW) gain in high fat‐fed, obese mice (P < 0.01) was observed compared to controls. EGCG treatment increased fecal lipid content by 29.4% (P < 0.05) compared to high fat‐fed control, whereas in vitro, EGCG dose‐dependently inhibited PL (IC₅₀ = 7.5 µmol/l) in a noncompetitive manner with respect to substrate concentration. (?)?Epicatechin‐3‐gallate exhibited similar inhibitory activity, whereas the nonester‐containing (?)?epigallocatechin did not. In conclusion, EGCG supplementation reduced final BW and BW gain in obese mice, and some of these effects may be due to inhibition of PL by EGCG.