Effect of antihypertensive treatment on kidney function in diabetic nephropathy.

The effect of long term, aggressive antihypertensive treatment on kidney function in diabetic nephropathy was studied prospectively in 11 insulin dependent diabetics (mean age 30). During the mean pretreatment period of 32 (range 23-66) months the glomerular filtration rate decreased significantly and albuminuria and the arterial blood pressure increased significantly. During the 72 (range 32-91) month period of antihypertensive treatment the average arterial blood pressure fell from 143/96 mm Hg to 129/84 mm Hg and albuminuria decreased from 1038 micrograms/min to 504 micrograms/min. The rate of decline in the glomerular filtration rate decreased from 0.89 (range 0.44-1.46) ml/min/month before treatment to 0.22 (range 0.01-0.40) ml/min/month during treatment. The rate of decline in the glomerular filtration rate was significantly smaller during the second three years compared with the first three years in patients who received long term antihypertensive treatment (greater than or equal to 6 years). One patient died from acute myocardial infarction (glomerular filtration rate 46 ml/min/1.74 m2). Effective antihypertensive treatment postpones renal insufficiency in diabetic nephropathy.     

Decrease in intestinal permeability to polyethylene glycol 1000 during development in the pig

Changes in intestinal permeability during postnatal development in the pig were investigated by using different-sized polyethylene glycols in the Mr 766-1338 range (polyethylene glycol 1000) as permeability probes. Pigs of varying age, newborn (Oh), 36-45 h old and 22-28 days old, were gavage fed polyethylene glycol 1000 together with the macromolecular markers bovine serum albumin, ovalbumin or FITC-labelled dextran 70,000. The 4-h blood serum concentrations of the different markers were determined and taken as an estimate of their intestinal transmission. In the newborn pigs, high serum levels of polyethylene glycols were obtained, concomitant with high serum levels of bovine serum albumin and FITC-dextran. After intestinal macromolecular closure in the 36-45 h-old pigs, lower serum polyethylene glycol levels were found, especially of those with a Mr greater than 1100 Da. In the 22-28 days-old pigs, polyethylene glycol levels were reduced to one-tenth or less of those in the 36-45 h-old pigs, with the levels decreasing markedly with increasing molecular size. These results show that there is a correlation between the intestinal permeability of polyethylene glycols, especially those larger than 1100, and macromolecules in the newborn pig around intestinal closure, suggesting that such polyethylene glycols traverse the gut by the macromolecular route. During later development, further intestinal maturation results in a markedly reduced permeability to polyethylene glycol 1000.     

A Computational Methodology to Screen Activities of Enzyme Variants

We present a fast computational method to efficiently screen enzyme activity. In the presented method, the effect of mutations on the barrier height of an enzyme-catalysed reaction can be computed within 24 hours on roughly 10 processors. The methodology is based on the PM6 and MOZYME methods as implemented in MOPAC2009, and is tested on the first step of the amide hydrolysis reaction catalyzed by the Candida Antarctica lipase B (CalB) enzyme. The barrier heights are estimated using adiabatic mapping and shown to give barrier heights to within 3 kcal/mol of B3LYP/6-31G(d)//RHF/3-21G results for a small model system. Relatively strict convergence criteria (0.5 kcal/(molÅ)), long NDDO cutoff distances within the MOZYME method (15 Å) and single point evaluations using conventional PM6 are needed for reliable results. The generation of mutant structures and subsequent setup of the semiempirical calculations are automated so that the effect on barrier heights can be estimated for hundreds of mutants in a matter of weeks using high performance computing.     

Lipases fromRhizomucor miehei andHumicola lanuginosa: Modification of the lid covering the active site alters enantioselectivity

The homologous lipases fromRhizomucor miehei andHumicola lanuginosa showed approximately the same enantioselectivity when 2-methyldecanoic acid esters were used as substrates. Both lipases preferentially hydrolyzed theS-enantiomer of 1-heptyl 2-methyldecanoate (R. miehei:E _S =8.5;H. lanuginosa:E _S =10.5), but theR-enantiomer of phenyl 2-methyldecanoate (E _R =2.9). Chemical arginine specific modification of theR. miehei lipase with 1,2-cyclohexanedione resulted in a decreased enantioselectivity (E _R =2.0), only when the phenyl ester was used as a substrate. In contrast, treatment with phenylglyoxal showed a decreased enantioselectivity (E _S =2.5) only when the heptyl ester was used as a substrate. The presence of guanidine, an arginine side chain analog, decreased the enantioselectivity with the heptyl ester (E _S =1.9) and increased the enantioselectivity with the aromatic ester (E _R =4.4) as substrates. The mutation, Glu 87 Ala, in the lid of theH. lanuginosa lipase, which might decrease the electrostatic stabilization of the open-lid conformation of the lipase, resulted in 47% activity compared to the native lipase, in a tributyrin assay. The Glu 87 Ala mutant showed an increased enantioselectivity with the heptyl ester (E _S =17.4) and a decreased enantioselectivity with the phenyl ester (E _R =2.5) as substrates, compared to native lipase. The enantioselectivities of both lipases in the esterification of 2-methyldecanoic acid with 1-heptanol were unaffected by the lid modifications.     

Does trans-lesion synthesis explain the UV-radiation resistance of DNA synthesis in C. elegans embryos?

Over 10-fold larger fluences were required to inhibit both DNA synthesis and cell division in wild-type C. elegans embryos as compared with other model systems or C. elegans rad mutants. In addition, unlike in other organisms, the molecular weight of daughter DNA strands was reduced only after large, superlethal fluences. The molecular weight of nascent DNA fragments exceeded the interdimer distance by up to 19-fold, indicating that C. elegans embryos can replicate through non-instructional lesions. This putative trans-lesion synthetic capability may explain the refractory nature of UV radiation on embryonic DNA synthesis and nuclear division in C. elegans.     

Some characteristics of intimal folds in the rabbit aorta

A stereomicroscopic study of fresh rabbit aorta has shown that the intimal folds form a special pattern which reappears when the aorta is relaxed after stretching. The pattern of intimal folds seems to be adapted to and may be the result of continuously repeated movements of the vessel wall. This supports the view hat intimal folds are present in vivo.     

A synchrotron radiation X-ray diffraction study of the crystallinity of tendon fibres

The equatorial diffraction pattern of tendon collagen fibres was measured during short successive exposures at different lengths using a double focusing X-ray synchrotron radiation camera with film and with an area detector. Similarly, patterns from thin fibres from premature rats were recorded. The patterns unambiguously illustrate the relationship between fibre crystallinity and the age of the animal. Further, the results indicate that in the initial part of the linear region of the stiffness-versus-length curve, the collagen fibres are characterized by a quasihexagonal arrangement of collagen molecules, whereas at the end of this region, the molecular arrangement becomes hexagonal.     

Anthraquinones as phytoalexins in cell and tissue cultures of Cinchona spec.

The addition of autoclaved mycelia of Aspergillus niger and the known phytopathogenic fungus Phytophtora cinnamomi to cultured cells of Cinchona ledgeriana Moens. caused a marked increase in the anthraquinone content of the plant cells. This finding in combination with the antimicrobial activity of the anthraquinones isolated from calli of Cinchona pubescens Vahl. led to the conclusion that anthraquinones are phytoalexins.Abbreviations 2,4-D 2,4-dichlorophenoyacetic acid - TLC thin-layer chromatography - AQ anthraquinone - DW dry weight