Use of associating polymers as multifunctional thickeners: studies of Their structure in aqueous solutions via nmr, qels, fluorescence, And rheology measurements

The solution properties of an associating polymer were studied by NMR, quasi‐elastic light scattering (QELS), fluorescence, and rheology measurements. An associative thickening (AT) polymer was designed having a nonionic poly(ethylene oxide) backbone with long alkyl chains at both ends to achieve high viscosity even at relatively high salt concentrations and over a wide pH range. This study focuses on the associative state of the polymer in aqueous solutions at various polymer concentrations. In a fluorescence probe study using pyrene a spectral change in the I₃/I₁ ratio was observed for pyrene at a polymer concentration (C_p) of 3 x 10^‐4%, indicating an apparent critical concentration (cmc) of the amphiphilic polymer. The viscosity, self‐diffusion coefficient (D_sel), and hydrodynamic size (R_h) distribution measurements at various C_p all suggest that there is a second transition at C_p? 0.4%. Although we observed the discontinuity in viscosity, D_sel, and R_h at C_p? 0.4%, no changes in the relaxation times (T₁ and T₂) were recognized for either the alkyl chain or the ethylene oxide moiety of the polymer at C _p= 0.1–1%. These data suggest that there are no structural changes or phase transitions at C_p? 0.4%, but that intermicellar networks are presumably formed by bridging of the end alkyl groups of the polymer, which is driven by hydrophobic forces. Because the polymer forms networks by hydrophobic interaction and the polymer itself is nonionic, the viscosity of the polymer solution was influenced very little by either the addition of salt or a pH change, as would be expected. The dynamic viscoelastic study revealed that the polymer solution exhibits a single mode Maxwell type relaxation behavior with a terminal relaxation time of about 0.61 s, which imparts a unique flow appearance to the polymer solutions. The time course measurements of the dynamic elastic modulus of the stratum corneum revealed that the polymer has excellent potential for skin softening. It was concluded that the associative thickening polymer not only is a useful thickener with a salt and pH tolerance but also has beneficial skincare effects.     

Bile acid metabolism in young-old parabiotic rats

Serum cholesterol, triglyceride and phospholipid levels, liver cholesterol concentration, bile flow, biliary cholesterol, phospholipid and bile acid secretion rates, fecal sterol and bile acid levels and their bile acid compositions were examined in young-old parabiotic rats and compared with those in young and old control rats and young-young parabiotic rats. Bile acid composition was expressed in terms of the cholic acid group/chenodeoxycholic acid group (CA/CDCA) ratio. Body weight (BW) gain decreased after parabiosis especially in old rats, but the liver weight (g/100 g BW), diet-intake, feces dry weight, liver cholesterol concentration and fecal sterol level were almost the same in all the groups. The biliary bile acid secretion rate was higher and the fecal bile acid level was lower in old rats than those in young rats but both the levels became comparable with those in young rats after parabiosis of old rats with young rats. Young rats, however, showed no changes in these levels after parabiosis. The serum cholesterol level and the biliary and fecal CA/CDCA ratios in old rats were higher than those in young rats but decreased after parabiosis with young rats, although they were still higher than those in young rats. The serum cholesterol level in young rats increased after parabiosis with old rats, but not after parabiosis with young rats, and the fecal bile acid level and the CA/CDCA ratio were not changed in either case. It is concluded from these findings that the serum cholesterol level and the CA/CDCA ratio increased with age and that these increases were prevented after parabiosis with young rats, while young rats, although their serum cholesterol level was increased, showed no increase in the CA/CDCA ratio after parabiosis with old rats.     

Early expression of a malignant phenotype of familial hypertrophic cardiomyopathy associated with a Gly716Arg myosin heavy chain mutation in a Korean family

The clinical course and prognosis of familial hypertrophic cardiomyopathy (HCM) are different according to the type of mutation in the genes for sarcomere proteins. It has been disputed that a mutation, which occurs at a functionally important region in the sarcomere proteins, may increase the penetrance and expressivity of the disease. We searched for a causative mutation in an HCM family, which is characterized by early expression of clinical phenotype, high incidence of sudden death at young ages, and progressive heart failure in adults. Among the 32 family members in 4 generations, 13 were affected; 4 died suddenly before age 16, 2 children have already had full expression of the cardiac hypertrophy, and other adults have either progressive heart failure or poor left ventricular systolic functions. PCR-SSCP (polymerase chain reaction-single strand confirmation polymorphism) analysis of genomic DNAs isolated from peripheral blood leukocytes of the family members identified a Gly716Arg mutation in the cardiac beta-myosin heavy chain gene, which was cosegregated with the clinical phenotype. The mutation is localized near a functionally important site of the myosin heavy chain, the 2 active thiols, which contribute to the adenosine triphosphatase activity of myosin S1. This family provides further evidence that the mutation, which occurs at a functionally important site of the myosin heavy chain, is associated with the high penetrance and early expression of HCM.     

Production of reactive oxygen species and release of L-glutamate during superoxide anion-induced cell death of cerebellar granule neurons

This study focuses on the different efficiencies of secretion of two fungal cutinases by Saccharomyces cerevisiae, a wild-type cutinase (CY000) and a hydrophobic mutant cutinase (CY028). Both cutinases are placed under control of the GAL7 promoter, by which the expression levels can be regulated. Wild-type cutinase was secreted at up to 25 mg per g (dry weight), while CY028 was secreted at a level of 2 mg per g (dry weight); this difference is nearly independent of the expression level. Pulse-chase experiments revealed that whereas CY000 cutinase is secreted, CY028 is irreversibly retained in the cell. Immunogold labelling followed by electron microscopy revealed colocalization of CY028 with immunoglobulin heavy-chain binding protein (BiP) in the endoplasmic reticulum (ER). The increase of wild-type cutinase expression did not result in higher levels of the molecular chaperone BiP, but BiP levels are raised by increased induction of the hydrophobic mutant cutinase. Immunoprecipitation studies showed that in contrast to the wild-type cutinase, the hydrophobic mutant cutinase interacts with BiP. These results indicate that the introduction of two exposed hydrophobic patches in cutinase results in a higher affinity for BiP which might cause the retention of this mutant cutinase in the ER.     

A 50-mW/ch 2.5-Gb/s/ch data recovery circuit for the SFI-5 interface with digital eye-tracking

This paper describes a 2.5-Gb/s/ch digital data recovery (DR) circuit for the SFI-5 interface. Although minimizing the circuit area has become critical in multibit interfaces such as the SFI-5, few studies have proposed a practical method of reducing the area of data recovery circuits. We introduce a digital-PLL-type DR circuit design with eye-tracking, which we developed to minimize the circuit area and power consumption without degrading tolerance against jitter. This novel method of data recovery enabled us to simplify the circuit design against process, voltage, and temperature variations. Design considerations on how to eliminate high-frequency jitter and how to track long-term wander are described. The design for 2.5-GHz clock distribution is also discussed. The area of the DR circuit, fabricated with 0.18-/spl mu/m SiGe BiCMOS technology, is 0.02 mm/sup 2//ch, and its power consumption is 50 mW/ch at 1.8 V. The measured tolerance against jitter at 2.5 Gb/s is 0.7 UI peak-to-peak, which satisfies the jitter specifications for the SFI-5.     

Trochlear nerve enhancement on three-dimensional magnetic resonance imaging in Fisher syndrome

PURPOSE: To examine the lesion associated with external ophthalmoplegia in Fisher syndrome using three-dimensional magnetic resonance imaging (3-D MRI). METHOD: Case report. A 65-year-old woman with Fisher syndrome was investigated by gadolinium-enhanced 3-D MRI. RESULT: The extramedullary portion of the left trochlear nerve was enhanced. CONCLUSION: Contrast-enhanced 3-D MRI revealed that the lesion responsible for the external ophthalmoplegia in Fisher syndrome is located in the extramedullary portion of the trochlear nerve.     

Molecular cloning and functional expression of a water-soluble chlorophyll protein, a putative carrier of chlorophyll molecules in cauliflower

A cDNA for a water-soluble chlorophyll (Chl) protein (WSCP) from cauliflower (Brassica oleracea L. var botrys) was cloned and sequenced. The cDNA contained an open reading frame encoding 19 residues for a signal peptide and 199 residues for the mature form of WSCP. The sequence showed extensive homology to drought-stress-related, 22-kDa proteins in some Brassicaceae plants. Functional WSCP was expressed in Escherichia coli as a fusion protein with a maltose-binding protein (MBP). When the recombinant MBP-WSCP was incubated with thylakoid membranes, the MBP-WSCP removed Chls from these membranes. During this process, the monomer of the apo-MBP-WSCP successfully bound Chls and was converted into tetrameric holo-MBP-WSCP. The reconstituted MBP-WSCP exhibited absorption and fluorescent spectra identical to those of the native WSCP purified from cauliflower leaves. The Chl a/b ratio in native WSCP indicates a high content of Chl a, which was mainly due to the higher affinity of MBP-WSCP for Chl a. WSCP is the first example of a hydrophilic protein that can transfer Chls from thylakoid hydrophobic proteins. Possible functions of WSCP are discussed.     

A case of infiltration of scar of sarcoidosis after blepharoplasty

Plasma viscosity is mainly determined by large non-spherical proteins. In Type 1 diabetes mellitus, plasma viscosity increases with deterioration of diabetic control. Since protein glycation and formation of advanced glycosylation end products (AGEs) alter the structural and functional properties of proteins, AGEs might influence the rheological properties of plasma proteins. Therefore, we investigated the influence of plasma-AGEs on plasma viscosity in 34 normoalbuminuric diabetic patients (17 Type 1, 17 Type 2) with normal renal and liver function. In an additional experiment, 6 ml plasma of 9 healthy volunteers were incubated under sterile conditions for 14 days at 37.5 degrees C in the presence of 5.2 and 32.9 mmol l(-1) glucose. In diabetic patients, plasma-AGE levels were not correlated with plasma viscosity. Plasma-AGE levels in healthy controls (246 +/- 37 U ml[-1], mean +/- SD) were raised significantly (p<0.001) after the incubation at 37.5 degrees C (392 +/- 57 U ml[-1] and 552 +/- 58 U ml[-1], respectively). However, no difference was found in plasma viscosity pre- and post-incubation (pre-incubation: 1.25 +/- 0.04 mPas, post-incubation: 1.23 +/- 0.03 and 1.24 +/- 0.03, respectively). We conclude that there is no influence of plasma-AGEs on plasma viscosity.     

A mutation in plasma platelet-activating factor acetylhydrolase (Val279-->Phe) is a genetic risk factor for stroke

BACKGROUND AND PURPOSE: Platelet-activating factor (PAF) is a phospholipid with multiple actions that include thrombosis and inflammation. It is inactivated by a plasma enzyme, PAF acetylhydrolase. Deficiency of this enzyme in plasma is caused by a missense mutation in the gene (Val279-->Phe). We have studied a possible association of this mutation with the risk of stroke. SUBJECTS AND METHODS: We studied 120 consecutive patients with cerebral thrombosis. The control group consisted of 134 patients matched for age and sex with minor complaints but without stroke. Genomic DNA was analyzed for the mutant allele by a specific polymerase-chain reaction. Plasma PAF acetylhydrolase activity was determined by the method of Stafforini et al. RESULTS: The prevalence of the mutant gene was 43.4% in stroke patients (39.2% heterozygotes and 4.2% homozygotes), which was significantly higher than the 25.4% in control subjects (22.4% heterozygotes and 3.0% homozygotes) (chi 2 = 9.22, P < .01). The prevalence was slightly higher in stroke patients without hypertension than those with hypertension, but the difference was not significant. The patients with family histories of stroke had a slightly higher but not a significant prevalence of the mutant gene as compared with those without family histories of stroke. Plasma PAF acetylhydrolase activity was higher in patients than in control subjects, in normal subjects, or patients with a heterozygous genotype. CONCLUSIONS: These results suggest that plasma PAF acetylhydrolase deficiency may be a risk factor for stroke. This may explain the relatively high prevalence of stroke in Japan, as the mutation is more common among Japanese than Caucasians.