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Kunio Kawamura

Publications and source records attributed to Kunio Kawamura.

10 recordsLinked to original sources
PubMed2006

Civilization as a biosystem examined by the comparative analysis of biosystems.

Darwinian evolutionary theory has played a central role in the life sciences. However, this principle is rarely applied to exceptional life-like systems such as human societies and the life-like chemical systems associated with the origin of life. For a description of the nature of these exceptional life-like biosystems, the development of alternative approaches is necessary. The existence of analogies among biosystems at different hierarchical levels has frequently been discussed. The present paper, however, focuses on the analogies of the structures and functions of different biosystems, based on the following perspectives. The roles of an individual biosystem and its building blocks in relation to the environment are evaluated from the standpoint of the hierarchies of organisms, whereby the principle of which hierarchy is regarded as an "individual" biosystem is proposed. In addition, the definition and characteristics of civilization are discussed on the basis of this principle. The analogies between cell-type systems, civilizations, ecosystems, and other biosystems are qualitatively evaluated. It is reasonable to regard all biosystems as possessing clear or ambiguous boundaries. Biosystems at higher levels than prokaryotes comprise both living and non-living building blocks, while prokaryotes comprise only non-living building blocks. The similarities concerning the interactions among the building blocks in relation to their environment are also discussed. Furthermore, the analogy between different biosystems concerning metabolism, self-reproduction, mutation, the relationship between genotype and phenotype (information and function), individuality, and stability are evaluated. The proposed analytical approach not only provides an insight into the characteristics of civilizations as biosystems, but also the characteristics of biosystems at different hierarchical levels.

Biological Evolution↗
PubMed2005

Consecutive elongation of alanine oligopeptides at the second time range under hydrothermal conditions using a microflow reactor system.

During the course of the study of the hydrothermal stability of alanine oligopeptides, a small amount of oligopeptides longer than the starting oligopeptides was found in the reaction products. On the basis of this unexpected finding and the investigation of the reaction mechanism, the elongation of oligopeptides using (Ala)3, (Ala)4, and (Ala)5 was attempted in aqueous solution at 275-310 degrees C within the second time range using a microflow reactor system. The elongation of (Ala)4 and (Ala)5 succeeded in the presence of an excess amount of Ala monomer. This is probably due to the fact that the elongation rate is competitive or somewhat faster than the degradation of peptide bonding. On the contrary, the elongation of (Ala)3 was not possible since it was immediately converted to diketopiperazine.

Alanine↗
PubMed2003

Kinetics and activation parameter analyses of hydrolysis and interconversion of 2',5'- and 3',5'-linked dinucleoside monophosphate at extremely high temperatures.

Kinetic analysis of hydrolytic stability of 2',5'- and 3',5'-linked dinucleoside monophosphate (N(2)'pN and N(3)'pN) was successfully performed in aqueous solution at 175-240 degrees C using a new real-time monitoring method for rapid hydrothermal reactions. The half-lives of NpN were in the range 2-8 s at 240 degrees C and apparent activation energy decreases in the order U(2)'pU>A(2)'pA>G(2)'pG>U(3)pU approximately C(3)'pC>A(3)pA. The stability of phosphodiester bond was dependent on the types of base moiety and phosphodiester linkages, but no systematic correlation was found between the structure and stability. The interconversion of 2',5'-adenylyladenosine monophosphate (A(2)'pA) and 3',5'-adenylyladenosine monophosphate (A(3)'pA) was enhanced in the presence of D- or L-histidine. The rate constants of degradation of NpN were dissected into the rate constants of hydrolysis and interconversion between N(2)'pN and N(3)'pN using a computer program SIMFIT. Kinetic analysis supports the mechanism that imidazolium ion and imidazole catalyze interconversion and hydrolysis even under hydrothermal environments. The activation parameters for the hydrolysis and interconversion of NpN were systematically determined for the first time from the temperature dependence of the rate constants, where both DeltaH(app)( not equal ) and DeltaS(app)( not equal ) for 2',5'-linked NpN are larger than those for 3',5'-linked NpN. These parameters support the pseudorotation mechanism through pentacoordinate intermediate from 2',5'- and 3',5'-linked NpN, where the average value of DeltaH( not equal ) (pseudorotation) was estimated to be 30+/-18 kJ mol(-1) at 175-240 degrees C.

Dinucleoside Phosphates↗
PubMed2003

In situ UV-VIS detection of the association of water-soluble anionic porphyrin and aromatic bases in aqueous solution at high tempeatures using a capillary flow hydrothermal reactor system.

The association between anionic water-soluble porphyrin and aromatic heterocyclic bases has been investigated to demonstrate the usefulness of a new in situ UV-VIS monitoring method of hydrothermal reactions. Spectral and absorbance changes in the presence of bases were possible to be detected by the new method at temperatures up to 150 degrees C. The association constants (K(ass,1)) were determined from the absorbance-base concentration curves. The logarithmic values of K(ass,1) were proportional to the number of rings of the bases, but this relationship became ambiguous beyond 100 degrees C. This fact indicates that stacking between porphyrin and bases does indeed become weak at high temperatures.

Journal Article↗
PubMed2002

A new approach for the cooperative chemical evolution of nucleic acids and proteins under the primitive earth environment.

In order to evaluate cooperative chemical evolution of nucleic acids and proteins, we have examined possible activity of thermal copolymers of amino acids (TCAA) for prebiotic formation and degradation of RNA. Several types of TCAA involving aromatic amino acids were prepared and the influence on the template-directed formation of oligoguanylate and prebiotic ribonuclease activity were kinetically studied.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Consideration of media fill tests for evaluation and control of aseptic processes: a statistical approach to quality criteria.

The concept of upper and lower statistical confidence limits has been introduced to the current media fill tests used for the assurance of aseptic operation. Results of media fill tests can be evaluated with rationale and interpreted more clearly by introducing the upper and lower limits for the number of observed positive units. Quality criteria derived by the misuse of statistics should be reconsidered. Media fill tests are one of the most useful methods for the evaluation of aseptic filling processes, and acceptance criteria have been issued in various official compendia. In some official compendia, various combinations of the number of media fills and the number of detected allowable contaminated units have been indicated based on the misuse of statistics. This study has statistically revealed that the larger number of fills allows for the worse average accepted quality. This study has shown that media fill tests can be used for the evaluation of aseptic operation with fully scientific and statistical rationale by evaluating the statistical lower limit for the number of positive units observed. This study proposed that the new criteria should be simply expressed as the process should be in a controlled state and can manufacture product whose sterility can be statistically assured with 95% confidence level.

Asepsis↗
PubMedDate not supplied

Role of the wireless thermologger system in the management of the autoclave unequipped with sensor ports.

Recently, the wireless thermologger system was developed. It consists of a wireless logger and the attached computer system. The wireless logger has a wireless structure and can be placed anywhere in the sterilizer chamber for thermometry. In the present study, thermal evaluations were performed twice using the wireless thermologger system in the sterilizer chamber of the prevacuum autoclave unequipped with sensor ports when it failed to pass the Bowie-Dick test and underwent mechanical repairs. Thermometry was performed when the Bowie-Dick test cycle was operated. The heat up time was measured in the range of 120.0-134.0 degrees C. The F0 value was calculated with the reference temperature at 121.0 degrees C and Z value at 10 degrees C when the sterilization temperature was over 120.0 degrees C. The first thermal evaluation was performed after three air-leaking points were repaired along with the replacement of the vacuum pump and the thermosensor. It revealed that the heat-up time was 4 min and 42 s and the F0 value was 137.5. After the temperature control systems were adjusted using the process calibrator in the prevacuum autoclave, the second thermal evaluation revealed that the heat up time was 2 mins 1 s and the F0 value was 102.7. The present study suggests that the wireless thermologger system is useful in the management of the autoclave unequipped with sensor ports when it undergoes mechanical repairs.

Electric Wiring↗
PubMedDate not supplied

A novel approach to the statistical evaluation of media fill tests by the difference from no contamination data.

It is obvious that, in the media fill test and process simulation test, positive numbers in total fills should not have any significant difference from zero or asepsis. There are many reports concerning the definition of "sterility" or "asepsis." However, any scientific and practical methods to demonstrate "no significant difference from zero" have not been reported up to now. The existing criteria, such as "less than 0.1%," "less than 0.05%," and "less than two positives" are not appropriate to assure the integrity of processes, and sometimes lead to erroneous results. The purpose of this report is to demonstrate novel, reasonable and practical methods and criteria based on scientific and statistical consideration. According to the ISO 13408-1 Aseptic Processing of Health Care Products, Part 1 (1998), General Requirement for Aseptic Processing, the action level for the number of positive units in media fill tests is specified as 0.1%, and the alert level is 0.05%. In this paper it is shown that the existing ISO standard and other official methods are inappropriate in that zero contaminated units (sterile product) is outside the confidence range of probable distribution of contaminated units, even though the contaminated units are less than 0.1% in larger numbers of fills, and even less than 0.05%. This indicates that the limit of 0.1% or 0.05% is inappropriate in cases of larger numbers of fills. For sterile products, the number of contaminated units other than "zero" at the statistical confidence range must be judged to be contaminated units in process and as non-sterile. In order to harmonize this criteria-"no significant difference from zero"-with the existing criteria, the new criteria may be combined with only the existing criteria of 0.05% in smaller number of fills.

Drug Contamination↗