Extension of Einstein's viscosity equation to that for concentrated dispersions of solutes and particles.

A viscosity equation for concentrated solutions or suspensions is derived as an extension of Einstein's hydrodynamic viscosity theory for dilute dispersions of spherical particles. The derivation of the equation is based on the calculation of dissipation of mechanical energy into heat in the dispersion, subtracting the energy dissipation in the portion of solutes or particles. The viscosity equation derived thus was well fitted to the viscosity-concentration relationship of the concentrated aqueous solutions of glucose and sucrose. For the suspensions of bakers' yeast, the concentration dependency of viscosity was expressed well with some modification for the flow pattern around suspended particles. It is suggested that these viscosity equations can be widely applied to both diluted and concentrated dispersions of various solutes and particles.

Finasteride in the treatment of Japanese men with male pattern hair loss.

Finasteride is a type 2 5 alpha-reductase inhibitor that inhibits conversion of testosterone to dihydrotestosterone, a key mediator of male pattern hair loss (androgenetic alopecia). The objective of this study was to identify the optimal dosage of finasteride and to evaluate its efficacy and safety in the treatment of Japanese men with male pattern hair loss. In this double- blind randomized study, 414 Japanese men with male pattern hair loss received finasteride 1 mg (n = 139), finasteride 0.2 mg (n = 137), or placebo (n = 38) once daily for 48 weeks. Efficacy was evaluated by global photographic assessment, patient self-assessment, and investigator assessment. All efficacy endpoints showed significant improvement with finasteride therapy by 12 weeks (p < 0.05 versus placebo). At 48 weeks, 58%, 54%, and 6% of men in the finasteride 1 mg, finasteride 0.2 mg, and placebo groups, respectively, had improved based on assessments of global photographs. All efficacy endpoints were numerically superior for the 1 mg dose over the 0.2 mg dose at 48 weeks. Finasteride treatment was generally well tolerated. Finasteride 1 mg\day slows hair loss and improves hair growth in Japanese men with male pattern hair loss.

Theoretical correlation between viscosities at dynamic and steady flow states in Aureobasidium pullulans culture fluids.

For the culture fluid and exopolysaccharide solution of the fungus Aureobasidium pullulans in a previous study, the angular frequency dependence of dynamic viscosity is well superimposed on the shear rate dependence of steady flow viscosity. For various polymeric fluids, the superimposition of the dependencies of steady flow viscosity and dynamic viscosity has also been realized. In this study, it is derived that, by assuming the sinusoidal oscillating flow of a viscoelastic fluid, complex viscosity is equivalent to viscosity in a steady flow measurement. A similar relation may also hold for the dynamic viscosity of an ideal viscous fluid. Generally, the measurement of the steady flow viscosity deprives a viscoelastic fluid of its elastic nature due to the disruption of the network structure causing the viscoelasticity. For the culture fluid and exopolysaccharide solution of A. pullulans, the correlation between the dynamic viscosity and the network structure was low. The dynamic viscosity in this case is consistent with the steady flow viscosity in the superimposing correlation.

Characteristic behavior of viscosity and viscoelasticity of Aureobasidium pullulans culture fluid.

Measurements of dynamic viscoelasticity and steady flow viscosity were made for culture fluids obtained by cultivation of Aureobasidium pullulans IAM 5060 with initial pHs of 6 and 7 and for exopolysaccharide (EPS) solutions obtained by removal of microbial cells. The molecular weight of EPS of the pH 6 culture is about 850,000, and that of the pH 7 culture is much larger. In the present study, the complex viscosity shifted to a considerably larger value than that of the steady flow viscosity. This differs from the Cox-Merz experience law which claims that there is a similarity between the angular frequency dependence of complex viscosity and the shear rate dependence of steady flow viscosity. On the other hand, the dynamic viscosity at small strain amplitude practically corresponded to the steady flow viscosity. The storage modulus of the pH 7 samples decreased markedly with a strain amplitude of more than 0.2, indicating that a dense network structure was formed. The linear region of the plot of viscoelasticity against strain amplitude was wider for the pH 6 culture, reflecting the stability of the network structure in this sample. The viscoelastic level of the EPS solution was a little greater than that of the culture fluid. This suggests that the viscoelasticity of the culture fluid is mainly caused by network structure forming among dissolved polysaccharides.

A modified model for non-newtonian viscosity behavior of Aureobasidium pullulans culture fluid.

The culture fluid of the fungus Aureobasidium pullulans and the exopolysaccharide solution obtained by removal of the microbial cells exhibit a marked shear dependence of viscosity. The viscosity in a high shear rate region was a little higher than that predicted by a non-Newtonian viscosity equation derived previously on the basis of the concept of traveling force. In a sample exhibiting such high shear rate dependence, a hydrodynamic effect based on the fluid structure of the binding of contacting polymers and suspended microbial cells on viscosity becomes comparatively significant. A model for the shear rate dependence of the viscosity is needed to elucidate the mechanism of the viscosity behavior. A term concerning the increase in viscosity caused by the binding of polymers and the microbial cells suspended in a medium was added to the previous viscosity equation. The experimental shear dependence of the viscosity was well simulated by the modified viscosity equation.

Accumulation of S-2-hydroxyethyl derivatives of L-cysteine and L-homocysteine by a methionine auxotroph of Escherichia coli with the addition of 2-mercaptoethanol to the culture.

We previously reported [J. Biosci. Bioeng., 94, 178-181 (2002)] that an Escherichia coli MetC-deficient mutant can accumulate L-cystathionine. When 2-mercaptoethanol was added to the culture medium during fermentation, the accumulation of L-cystathionine decreased and S-(2-hydroxyethyl)-L-cysteine and S-(2-hydroxyethyl)-L-homocysteine were accumulated.

Accumulation of L-cystathionine by an Escherichia coli mutant deficient in cystathionine beta-lyase.

An Escherichia coli mutant deficient in cystathionine beta-lyase was found to accumulate a substance detectable by ninhydrin reaction and chloride platinic acid reaction in its cells (rarely in the culture supernatant) when cultured with a limited amount (50-200 microg/ml) of L-methionine to support the growth. The product was released by freezing treatment and isolated by ion-exchange chromatography (cation exchange resin: Daiaion SK1B). It was identified as L-cystathionine by liquid chromatography-mass spectrometry, 13C- and 1H-nuclear magnetic resonance analyses and high-performance liquid chromatography (as its 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate derivative).

Theoretical and methodological studies of continuous microbial bioreactors.

This article reviews most of the author's studies on process development and reactor design for continuous microbial reactions. (1) Enzyme reactions of growing and non-growing microbial cells immobilized in agar gel beads were analyzed pertaining to the effects of external and internal diffusion of substrate on reaction kinetics. (2) Experimental correlations of production rates of beta-fructosidase and acid phosphatase with dilution rate of continuous culture were simulated based on an operon model for enzyme regulation. (3) Population dynamics of an amylase-producing bacteria and their mutant were discussed in relation to enzyme productivity in a continuous culture of spore-forming bacteria. (4) Plasmid mobilization in a mixed population of donor, recipient, and helper cells was investigated in a continuous culture as a model study of accidental release of a genetically modified plasmid into a natural environment. (5) A production rate increase of up to 100-fold was achieved by cell-recycle culturing of continuous acetic acid fermentation using a filter module with a hollow fiber membrane. (6) The feasibility of a continuous surface culture for the biooxidation of organic substances was ascribed to an enhanced oxygen absorption rate in the presence of a microbial film on a liquid surface. (7) Simultaneous separation of inhibitory products using an electrodialysis module during some organic acid fermentations was effective for increasing production in a continuous culture.

English version of the interim report published in 1998 by the members of the Advisory Committee on Atopic Dermatitis Severity Classification Criteria of the Japanese Dermatological Association.

The Japanese Dermatological Association established an advisory committee in 1995 to set up severity scoring systems for atopic dermatitis (AD). Its interim report was published in Japanese in the Japanese Journal of Dermatology (108: 1491-1496, 1998) by Chairman Hikotaro Yoshida. Because of the strong demand for an English version, we have decided to publish the report in English. This prospective study was designed to evaluate the status of 259 AD patients using Method 1, which involves a simple global evaluation of disease severity; Method 2, which involves global evaluation by summing severity scores obtained from five body regions (i.e. the head and neck, anterior and posterior trunks, and upper and lower limbs); Method 3, which consists of both assessment of the extent of involved areas at each of the five body regions and that of the severity scores of each eruption component observed in the most severely affected body region; and Method 4, which consists of the evaluation of only subjective components (daytime pruritus and sleep disturbance). Employing the results obtained with Method 1 as a tentative benchmark, we analyzed its correlation with those of Methods 2, 3 and 4 to statistically assess the validity and reliability of these methods. Method 2, Method 3 and the portion of Method 4 involving evaluation of only the subjective symptom of daytime pruritus but not the sleep disturbance were considered useful in evaluating AD severity.

English version of the concluding report published in 2001 by the Advisory Committee on Atopic Dermatitis Severity Classification Criteria of the Japanese Dermatological Association.

The Japanese Dermatological Association established an advisory committee in 1995 to develop a severity scoring system for atopic dermatitis (AD). Its interim and concluding reports were published in Japanese in the Japanese Journal of Dermatology (108: 1491-1496, 1998 and 111: 2023-2033, 2001). Because of the strong demand for an English version, we have decided to publish the reports in English. This manuscript is the English version of the concluding report. The interim report suggested that eruption components such as erythema, papule, erosion, crust, excoriation and lichenification with extent of involved areas in five body regions, including the head and neck, anterior and posterior trunks, and upper and lower limbs, were important items for assessing AD severity. Additionally, it was recommended that streamlining of eruption components was mandatory for improving the statistical validity and reliability. The committee members subsequently concentrated their efforts on this task, and finally proposed an Atopic Dermatitis Severity Classification Criteria of the Japanese Dermatological Association.

Improvement of foam breaking and oxygen-transfer performance in a stirred-tank fermenter.

This study examined a stirred-tank fermenter (STF) containing low-viscosity foaming liquids with an agitation impeller and foam-breaking impeller mounted on the same shaft. Results showed that the performance of the foam-breaking impeller can be improved by changing a conventional six-blade turbine impeller into a rod impeller as the agitation impeller. The volumetric oxygen-transfer coefficient, kLa, in the mechanical foam-control method (MFM) using a six-blade vaned disk as the foam-breaking impeller in the STF with the rod impeller was approximately five times greater than that of the chemical foam-control method (CFM) adding an anti-foaming agent in the STF with the six-blade turbine impeller. Application of the present method to the cultivation of Saccharomyces cerevisiae K-7 demonstrated that the cultivation time up to the maximum cell concentration was remarkably shorter than that achieved using a conventional CFM.