Quantitative measurement of cutaneous sensory response to vibration

This paper presents psychological and physical experiments carried out by using a vibrometer as an acoustical calibration apparatus. This study has shown the relationship between the vibratory sensibility and the electric signal generated in a living body. The threshold curve for square wave vibration is lower by 12.3 dB than that for sine wave vibration near 30 Hz. The stimulus level is taken as the horizontal axis, and potential variation and strengh evaluation are plotted on the vertical axis, the former has a nearly rectiliner relation with the latter.     

Arginine carboxypeptidase (CPR) in human plasma determined with sandwich ELISA.

There are two types of carboxypeptidases present in human blood, carboxypeptidase N (CPN) and arginine carboxypeptidase (CPR). CPR is generated during coagulation from a precursor (proCPR) which can be converted to the active form by trypsin in vitro. Since it is difficult to distinguish the two types of carboxypeptidases in human blood by the measurement of enzyme activity, we established a quantitative sandwich ELISA by which CPR can be quantitated. The amount of CPR in plasma, fresh serum and heated serum were essentially the same. Therefore the ELISA assay does not distinguish proCPR, activated CPR and inactivated CPR. With the ELISA method, CPR was quantitated in plasma from fifty patients with rheumatoid arthritis and eleven patients with severe hepatitis as well as healthy individuals. The amount of CPR in plasma obtained from patients with rheumatoid arthritis was not found to be lower than that of normal subjects. Furthermore, the patients who suffered severe hepatitis and had very low levels of CPR-total were fatal. This suggests that a decrease of CPR level might be a good indication of a patient's prognosis to death by hepatitis.     

Steady-state inhibitory kinetic studies on the ligand binding modes of Aspergillus niger glucoamylase.

Inhibitory activities of 1-deoxynojirimycin and gluconolactone on Aspergillus niger glucoamylase were studied in relation to the subsite structure of the enzyme. Although both of these inhibitors are considered to bind at subsite 1 of the enzyme active site, 1-deoxynojirimycin showed competitive type inhibition but gluconolactone was a mixed type (or noncompetitive type) inhibitor for the hydrolysis of p-nitrophenyl alpha-D-glucoside. The former type of inhibition suggested that the main binding mode of the substrate was productive, but the latter, nonproductive. A possible way of explaining these apparent inconsistent results is to assume that the main binding mode of the substrate is productive and gluconolactone forms a nonproductive ternary complex with the enzyme and the substrate.     

Influence of calcium on proliferation and phenotype alteration of cardiomyocyte in vitro

An accelerated weight gain is noted in the heart of Ca-deficient, hypertensive chick embryos maintained in a shell-less culture in vitro. We previously observed that the Ca handling property of cardiomyocytes isolated from the shell-less embryo is altered, i.e., faster Ca uptake, suggesting a requirement for adequate Ca supply and/or proper Ca handling in embryonic cardiac development. In this study, we have examined the function of Ca on cardiomyocytes by analyzing the effects of (1) various Ca concentration in the culture medium (NCa, 1.8 mmol/L; HCa, 2.8 mmol/L; LCa, 0.9 mmol/L), and (2) various modulators of Ca handling on cell proliferation and phenotype regulation in chick embryonic cardiomyocytes. The analytical parameters included cell number, DNA content, expression of cell cycle–specific and cardiomyocyte-specific proteins, and creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) enzyme activities. Cell number and total DNA were significantly larger (P < 0.01) in LCa cultures compared with those in NCa. The level of LDH was elevated (P < 0.01), but that of CPK was lowered in LCa. Expression of the G1-S–specific protein PCNA was raised, but that of the contractile proteins myosin and tropomyosin was substantially suppressed in LCa; in HCa, the cells did not proliferate as well, whereas the level of contractile proteins was higher. Thapsigargin, a sarcoplasmic reticulum (SR)-specific, Ca-ATPase inhibitor, simulated the effects of LCa by enhancing cell proliferation and lowering the expression of tropomyosin. These results suggest that culturing in low Ca concentration and inhibition of SR Ca pumping enhance myocardial cell proliferation and suppress sarcomeric protein expression, perhaps by inducing cellular de-differentiation. The in vitro effects of medium Ca concentration and Ca handling modulators on cardiomyocytes also suggest that the in vivo cardiomegaly of the SL embryos is a direct result of Ca-deficiency, and that Ca is important in the phenotype regulation of cardiomyocytes. J. Cell. Physiol. 177:289–298, 1998. © 1998 Wiley-Liss, Inc.     

Growth rate correlates negatively with protein turnover in Arabidopsis accessions

Previous studies with Arabidopsis accessions revealed that biomass correlates negatively to dusk starch content and total protein, and positively to the maximum activities of enzymes in photosynthesis. We hypothesized that large accessions have lower ribosome abundance and lower rates of protein synthesis, and that this is compensated by lower rates of protein degradation. This would increase growth efficiency and allow more investment in photosynthetic machinery. We analysed ribosome abundance and polysome loading in 19 accessions, modelled the rates of protein synthesis and compared them with the observed rate of growth. Large accessions contained less ribosomes than small accessions, due mainly to cytosolic ribosome abundance falling at night in large accessions. The modelled rates of protein synthesis resembled those required for growth in large accessions, but were up to 30% in excess in small accessions. We then employed ¹³CO₂ pulse‐chase labelling to measure the rates of protein synthesis and degradation in 13 accessions. Small accessions had a slightly higher rate of protein synthesis and much higher rates of protein degradation than large accessions. Protein turnover was negligible in large accessions but equivalent to up to 30% of synthesised protein day^?1 in small accessions. We discuss to what extent the decrease in growth in small accessions can be quantitatively explained by known costs of protein turnover and what factors may lead to the altered diurnal dynamics and increase of ribosome abundance in small accessions, and propose that there is a trade‐off between protein turnover and maximisation of growth rate.     

Establishment of germline-competent embryonic stem cell lines from the MSM/Ms strain

MSM/Ms is an inbred mouse strain established from the Japanese wild mouse, Mus musculus molossinus, which has been phylogenetically distinct from common laboratory mouse strains for about 1 million years. The nucleotide substitution rate between MSM/Ms and C57BL/6 is estimated to be 0.96%. MSM/Ms mice display unique characteristics not observed in the commonly used laboratory strains, including an extremely low incidence of tumor development, high locomotor activity, and resistance to high-fat-diet-induced diabetes. Thus, functional genomic analyses using MSM/Ms should provide a powerful tool for the identification of novel phenotypes and gene functions. We report here the derivation of germline-competent embryonic stem (ES) cell lines from MSM/Ms blastocysts, allowing genetic manipulation of the M. m. molossinus genome. Fifteen blastocysts were cultured in ES cell medium and three ES lines, Mol/MSM-1, -2, and -3, were established. They were tested for germline competency by aggregation with ICR morulae and germline chimeras were obtained from all three lines. We also injected Mol/MSM-1 ES cells into blastocysts of ICR or C57BL/6 × BDF1 mice and found that blastocyst injection resulted in a higher production rate of chimeric mice than did aggregation. Furthermore, Mol/MSM-1 subclones electroporated with a gene trap vector were also highly efficient at producing germline chimeras using C57BL/6 × BDF1 blastocyst injection. This Mol/MSM-1 ES line should provide an excellent new tool allowing the genetic manipulation of the MSM/Ms genome.     

Basophil-derived mouse mast cell protease 11 induces microvascular leakage and tissue edema in a mast cell-independent manner

Mouse mast cell protease 11 (mMCP-11) is the most recently identified member of the mouse mast cell tryptase family. This tryptase is preferentially produced by basophils in contrast to other members that are expressed by mast cells but not basophils. Although blood-circulating basophils have long been considered as minor and redundant relatives of tissue-resident mast cells, recent studies illustrated that basophils and mast cells play distinct roles in vivo. To explore the in vivo role of basophil-derived mMCP-11, here we prepared recombinant mMCP-11 and its protease-dead mutant. Subcutaneous injection of the wild-type mMCP-11 but not the mutant induced edematous skin swelling with increased microvascular permeability in a dose-dependent manner. No apparent infiltration of proinflammatory cells including neutrophils and eosinophils was detected in the skin lesions. The cutaneous swelling was abolished by the pretreatment of mice with indomethacin, a cyclooxygenase inhibitor, suggesting the major contribution of prostaglandins to the microvascular leakage. Of note, the cutaneous swelling was elicited even in mast cell-deficient mice, indicating that mast cells are dispensable for the mMCP-11-induced cutaneous swelling. Thus, basophil-derived mMCP-11 can induce microvascular leakage via prostaglandins in a mast cell-independent manner, and may contribute to the development of basophil-mediated inflammatory responses.