An Optimal Inspection and Replacement Policy

An optimal inspection and replacement policy is discussed for a unit which assumes any one of several Markov states. The policy evaluation function is the s-expected cost-per-unit-time over an infinite time span. The problem is formulated as a semi-Markov decision process with a modified policy-improvement routine. Some properties of the optimal policy are discussed, for example, the control limit rule holds and the inspection time interval becomes shorter as degradation progresses.     

About musicogenic epilepsy (author's transl)

A case of musicogenic epilepsy or psychomotor seizures supervening whenever the patient hears a certain tune is presented. Nearly 70 cases of musicogenic epilepsy have been documented so far. The findings in these cases including those encountered by ourselves may be summarized as follows: Musicogenic epilepsy is more common among middle-aged persons. In an unexpectedly large proportion of cases the cause is unknown. Among the organic causes, head injury is of the highest incidence. It is quite unlikely that brain bumor is responsible. There is no dementia or mental retardation as in some forms of reflex epilepsy. The seizure is overwhelmingly of the psychomotor type. The EEG pattern often suggests temporal lobe epilepsy. There seems to be no cerebral dominance. Different kinds of music can be the inducer, ranging from those primarily intended to stimulate the sense to those appealing to affect. The activating mechanism of the condition still remains obscure. In the strict sense of the word, the condition cannot be termed reflex epilepsy.     

Toyota's New Microprocessor-Based Diesel Engine Control System for Passenger Cars

A new microprocessor-based diesel engine control system was introduced into the Japanese market by Toyota Motor Corporation in August, 1982. This system controls fuel quantity, injection timing, idle speed, glow plug current, and intake air flow. Its characteristics are as follows: 1) significantly increased flexibility for system expansion through adoption of a microprocessor; 2) optimization of the governor and injection timing characteristics through table look-up and interpolation methods; 3) high accuracy of various processing procedures through the use of a newly designed microprocessor; 4) high control accuracy and quick response from an analog servo system through the use of a newly developed linear solenoid and noncontact variable inductance sensors; and 5) high safety and serviceability through the addition of various fail-safe and diagnostic functions.     

High-power output over 200 mW of 1.3 µm GaInAsP VIPS lasers

Maximum CW output power was investigated in GaInAsP 1.3μm V-grooved inner stripe on P-substrate (VIPS) lasers considering both cavity length and facet reflectivity. Long-cavity lasers show a strong dependence of maximum output power on front reflectivity. A CW light output over 200 mW was obtained at room temperature using a 700 μm long cavity laser with 5 and 98 percent reflectivity of the front and rear facets, respectively. The fundamental transverse mode operation was confirmed up to 170 mW. A coupled power over 110 mW into a single-mode fiber was achieved with a coupling efficiency of 58 percent. We have verified the high reliability under high power levels, as high as 75 percent of the maximum CW output powers at room temperature.     

Preparation of biologically active Ascaris suum mitochondrial tRNAMet with a TV-replacement loop by ligation of chemically synthesized RNA fragments

Ascaris suum mitochondrial tRNA Met lacking the entire T stem was prepared by enzymatic ligation of two chemically synthesized RNA fragments. The synthetic tRNA could be charged with methionine by A.suum mitochondrial extract, although the charging activity was considerably low compared with that of the native tRNA, probably due to lack of modification. Enzymatic probing of the synthetic tRNA showed a very similar digestion pattern to that of the native tRNA Met, which has already been concluded to take an L-shape-like structure [Watanabe et al. (1994) J. Biol. Chem., 269, 22902-22906]. These results suggest that the synthetic tRNA possesses almost the same conformation as the native one, irrespective of the presence or absence of modified residues. The method of preparing the bizarre tRNA used here will provide a useful tool for elucidating the tertiary structure of such tRNAs, because they can be obtained without too much difficulty in the amounts necessary for physicochemical studies such as NMR spectroscopy.     

Identification of matrix metalloproteinases (MMPs) in synovial fluid from patients with temporomandibular disorder

Proteolytic enzymes with gelatinolytic activity in the synovial fluid (SF) of temporomandibular joint (TMJ) arthropathies were assayed by gelatin-impregnated gel enzymography. SF samples were collected from 10 TMJs in patients with closed lock (CL) condition and 5 TMJs from asymptomatic healthy volunteers. Two proteinases with gelatinolytic activities at 92 kDa and 72 kDa were detected in both the normal and the diseased TMJs. Also detected were weak bands at molecular weights of 83 kDa and 66 kDa. All of these proteinase activities were inhibited by EDTA and tissue inhibitor of metalloproteinases (TIMP), required Ca2+ for activation, and were detected with gelatin but not casein as substrate, suggesting that these enzymes were matrix metalloproteinases (MMPs). The 72 kDa and 66 kDa bands further reacted with anti-MMP-2 antibody by Western blot analysis, and the proteinases in the TMJ-SF could cleave type IV collagen in vitro without any activation. These four activities identified by enzymography were, therefore, identified as 92 kDa-gelatinase (proMMP-9), 83 kDa-gelatinase (active MMP-9), 72 kDa-gelatinase (proMMP-2) and 66 kDa-gelatinase (active MMP-2). Densitometric analyses of these bands revealed higher levels of the active form of MMP-9 in the CL patients compared to controls. These findings suggest that MMP-2 and -9 could be dominant proteinases in the TMJ-SF and possibly reflect TMJ pathology.     

Normal B lymphocyte development but impaired T cell maturation in CD45-exon6 protein tyrosine phosphatase-deficient mice

The transmembrane tyrosine phosphatase CD45 is expressed in multiple isoforms on all nucleated hematopoietic cells, resulting from alternative splicing of variable exons. We generated mice with a mutation in the variable CD45 exon 6, using homologous recombination. In mice homozygous for the CD45-exon6 mutation, B cells and most T cells did not express CD45. Development of B cells appeared normal, although Ig mu-induced proliferation was completely abrogated. Thymocyte maturation was blocked at the transitional stage from immature CD4+CD8+ to mature CD4+ or CD8+ cells, and only a few T cells could be detected in peripheral lymphoid organs. Clonal deletion of superantigen-reactive T cells still occurred. Cytotoxic T cell responses to lymphocytic choriomeningitis virus were absent in CD45-exon6-/- mice. These data imply that CD45 is differentially required for the development and function of B and T lymphocytes.     

Effect of chronic tryptophan depletion on the circadian rhythm of wheel-running activity in rats

The effect of chronic treatment with a tryptophan (TRP)-free diet on the free-running circadian wheel-running rhythm and the central serotonergic system was investigated in blinded male rats. The long-term TRP-free diet did not change periods of activity, but disordered their patterns. This seemed to be due to masking, entrainment, enhancement of the morning activity, and obscuring of the activity onset as well as appearance of some periodic activities within the subjective night. A long-term TRP-fre diet decreased the concentration of TRP, 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in all brain regions tested: frontal cortex, hippocampus, thalamus, hypothalamus, midbrain, and pons. Density of 5-HT1A receptor binding was significantly decreased in the frontal cortex and hypothalamus, whereas no significant change was observed in the density of 5-HT2 receptor binding in all regions. These results suggest that the period of primary circadian pacemaker is not affected, but its oscillation, as well as the coupling strength between the primary and secondary pacemakers, is weakened by the dysfunction of the serotonergic system caused by chronic TRP depletion.     

Enhancement of rat urinary bladder tumorigenesis by lipopolysaccharide-induced inflammation

Chronic inflammation of the urinary tract is a significant risk factor for the development of urinary bladder cancer in humans. We previously demonstrated that weekly treatment with killed Escherichia coli enhanced rat urinary bladder tumorigenesis initiated by the carcinogen N-methyl-N-nitrosourea. We conducted the present study to determine whether lipopolysaccharide (LPS), a major cell wall component of E. coli, had a tumor-enhancing effect. LPS was instilled twice a week at three doses (100, 1.0, and 0.01 microgram/ml) into heterotopically transplanted rat urinary bladders which were treated with a single low dose (0.25 mg) of N-methyl-N-nitrosourea or vehicle. Rats treated with 100 micrograms/ml of LPS showed a significant increase in the incidence and number of tumors in the bladders pretreated with N-methyl-N-nitrosourea. Treatment with LPS alone did not induce tumors. The enhancing effects were associated with a marked increase in the numbers of polymorphonuclear leukocytes and an increase in the H2O2 concentration in the bladder lumen. Oxidative stress by reactive oxygen intermediates and a proliferative response of the carcinogen-exposed urothelium to the inflammatory stimulation appeared to play a significant role in tumor enhancement by LPS.