Mechanomyography of the human quadriceps muscle during incremental cycle ergometry

The mechanical activity of the human quadriceps muscle during maximal incremental cycle ergometry was investigated by mechanomyography (MMG). MMG and surface electromyography (EMG) recordings of vastus lateralis muscle activity were obtained from nine males. Cycle ergometry was performed at 60?rev/min and work load was incremented step wise by 20?W (3.2?Nm) every minute until volitional fatigue. The mean amplitudes of MMG (mMMG) and EMG (mEMG) during the contraction phase were calculated from the last six contractions in each load. The duration, load and work rate of exercise at exhaustion were 13.3 (1.6)?min, 44.1 (5.5)?Nm, 276.7 (34.7)?W, respectively. A linear relationship between mMMG and load was evident in each subject (r?=?0.868–0.995), while mEMG seemed to dissociate as the load became greater. In the grouped mean data, mMMG was linearly related to load whether aligned to the absolute (r?=?0.995) or maximal (r?=?0.995) load. Involvement of the noise component was further investigated by studying passive cycling by four subjects. Pedals were rotated passively for the first half of each stage (PAS) and the subject then pushed the pedals for the second half (ACT). In the lighter load region, the mMMG of ACT was as small as that of PAS. However, the change in the mMMG of PAS was very small compared with that of ACT. In conclusion, this study demonstrates a linear relationship between the mMMG of the quadriceps muscle and work load during maximal incremental cycle ergometry. The effect of movement noise was thought to be small and stable.     

Dilute solution properties of imogolite

Imogolite, a natural product in the clay fraction of Japanese soil, was characterized through its dilute solution properties. Various methods were employed for this characterization, including viscosity, sedimentation, static/dynamic light scattering, and small angle X-ray scattering. All these measurements have revealed consistently that imogolite is represented by a rigid thin rod within the accuracy of available theories, where its repeat unit is composed of twelve gibbsite units. Since the evaluation of the chain length from the observed quantities depends on the molecular weight distribution, its effect was also considered where M_w/M_n ≈ 1,2 was estimated from the sedimentation profile.     

Lyotropic mesophase of imogolite, 1. Effect of polydispersity on phase diagram

The acidic aqueous solution of imogolite is proposed to be an ideal lyotropic system. No temperature dependence was marked on the two phase boundary concentrations (A and B points) of imogolite solutions as predicted by the theories of Flory and Onsager. A satisfactory quantitative agreement was observed with Onsager's theory. The polydispersity of rod lengths was found to shift the A point towards lower concentrations than expected from theory.     

Cytoplasmic inclusions and virus-like particles in blast cells in acute lymphoblastic leukemia

Cytoplasmic inclusions and virus-like particles are described in blast cells of peripheral blood from a 16-year-old female with acute lymphoblastic leukemia. Three kinds of inclusions were identified on electron microscopy. The first type of inclusion was single membrane-bounded vacuoles, some of which contained virus-like particles, the second was lysosome-like structures, and the third appeared to be of mitochondrial origin. Virus-like particles were round in shape and had a diameter of 26 to 58 nm. They consisted of an electron-dense outer membrane and an electron-lucent core. At the present time the exact nature and significance of these virus-like particles still remain unclear.     

Scanning and transmission electron microscopic observations of the acute morphological response of the mouse urinary bladder to 4-ethylsulfonylnaphthalene-1-sulfonamide

A total of 75 BALB/cStCrlfC3H/Nctr male weanling mice were administered either 0 or 250 ppm of 4 ethylsulfonylnaphthalene-1-sulfonamide (ENS) in the diet for periods up to 14 days to evaluate the early morphological changes of the transitional epithelium of the urinary bladder with scanning (SEM) and transmission (TEM) electron microscopy. Primary TEM changes included hyperplasia of the epithelium, loosening of the intercellular junctions, autophagic vacuoles and electron dense granules in the mitochondria. Primary SEM changes included sloughing of epithelial cells, irregularity in the size and shape of the transitional epithelial cells and the presence of microvilli. Although pleomorphic microvilli were present after only three days of treatment with ENS, it appears that they are a transient observation in a series of morphological changes. The reversibility or transient nature of the pleomorphic microvilli may indicate that they are an acute toxic response and may not necessarily indicate a preneoplastic change.     

Effects of gap junction blocker on vasopressin and vasoactive intestinal polypeptide rhythms in the rat suprachiasmatic nucleus in vitro

We examined effects of gap junction blockers, octanol and halothane, on circadian rhythms in the release of arginine-vasopressin (AVP) and vasoactive intestinal polypeptide (VIP) in suprachiasmatic nucleus (SCN) slice cultures of the rat. Circadian rhythms in AVP and VIP release maintained when the SCN culture was treated with octanol for 42 h. However, the release of AVP and VIP showed no circadian rhythms after 7 days incubation with octanol or halothane. Circadian rhythmicity in the two peptide rhythms appeared after the removal of the drug from the culture medium. These findings suggested that the gap junction communication may be involved in intercellular coupling within each subpopulation of AVP or VIP neurons in the SCN.     

Detection of skeletal muscle fatigue using an accelerometer in dynamic cardiomyoplasty

 An animal experiment was done using six mongrel dogs that weighed 28 ± 3 kg to show that an accelerometer could detect skeletal muscle fatigue in dynamic cardiomyoplasty. Through left-side thoracotomy, the heart was exposed and an electrode to sense the heartbeat was positioned on the left ventricle. A left latissimus dorsi muscle flap (LDMF) was inserted into the left chest cavity and rolled around the heart. An accelerometer was put on the rolled LDMF to sense the ventricular acceleration by contraction of the LDMF and the heart. The LDMF was stimulated under these settings: pulse width, 210 μs; stimulation output, 6 V; burst frequency, 30 Hz; burst duration, 200 ms; synchronous ratio, 1 : 4; and synchronous delay, 66 ms. Output voltage from the accelerometer was recorded 1, 3, 5, 10, and 15 min after the beginning of stimulation. Percentages of the amplitude in all dogs after 3, 5, 10, and 15 min were 81 ± 10%, 63 ± 12%, 48 ± 11%, and 45 ± 14% of the values after 1 min, respectively. Significant differences were found between the values after 1 min and those after 3 min, between the values after 3 min and those after 5 min, and between the values after 5 min and those after 10 min. This study suggests that muscle fatigue is detectable with an accelerometer in actual dynamic cardiomyoplasty. Received: May 11, 2001 / Accepted: September 10, 2002 Acknowledgments This work was financially supported in a part by a Grant in Aid for Scientific Research (05671113) from the Ministry of Education, Science, and Culture of Japan. Correspondence to:H. Kuroda     

Loss of Hrs in the Central Nervous System Causes Accumulation of Ubiquitinated Proteins and Neurodegeneration

The endosomal sorting complex required for transport (ESCRT) proteins form multimolecular complexes that control multivesicular body formation, endosomal sorting, and transport ubiquitinated membrane proteins (including cell-surface receptors) to the endosomes for degradation. There is accumulating evidence that endosomal dysfunction is linked to neural cell degeneration in vitro, but little is known about the relationship between neural disorders and ESCRT proteins in vivo. Here we specifically deleted the hrs gene, ESCRT-0, in the neurons of mice by crossing loxP-flanked hrs mice with transgenic mice expressing the synapsin-I Cre protein (SynI-cre). Histological analyses revealed that both apoptosis and a loss of hippocampal CA3 pyramidal neurons occurred in the hrs^flox/flox;SynI-cre mice. Notably, the hrs^flox/flox;SynI-cre mice accumulated ubiquitinated proteins, such as glutamate receptors and an autophagy-regulating protein, p62. These molecules are particularly prominent in the hippocampal CA3 neurons and cerebral cortex with advancing age. Accordingly, we found that both locomotor activity and learning ability were severely reduced in the hrs^flox/flox;SynI-cre mice. These data suggest that Hrs plays an important role in neural cell survival in vivo and provide an animal model for neurodegenerative diseases that are known to be commonly affected by the generation of proteinaceous aggregates.     

Expression of cyclin D1, retinoblastoma gene protein, and p16 MTS1 protein in atypical adenomatous hyperplasia and adenocarcinoma of the lung

 To clarify the events leading to the disruption of cell growth control that occurs during the development of pulmonary adenocarcinoma (AC), we used immunohistochemistry to evaluate the expression of G1 cycle regulators, cyclin D1, Rb protein (pRb), and p16 MTS1 protein and the tumour proliferation marker, Ki 67, both in AC of the lung and in its precursor lesion, atypical adenomatous hyperplasia (AAH). The frequency of lesions with cyclin D1 overexpression was relatively high in AAH (47–89%), but was decreased in early AC (28%) and overt AC (35%). The loss of pRb expression was rare in both AAH (0–18%) and early AC (0%), and was infrequent even in overt AC (13%). The loss of p16 expression was also relatively infrequent in both the premalignant and the malignant lesions (11–25%). Our results suggest that overexpression of cyclin D1 is an early event and plays an important part in tumorigenesis in the case of lung AC. However, cyclin D1 overexpression is not required for the development and maintenance of a malignant phenotype. It is likely that some cyclin D1-independent pathways other than Rb and p16 abnormalities have an important role in the malignant transformation from AAH to early AC. Received: 8 July 1997 / 26 September 1997     

In vitro and ex vivo blood compatibility study of 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer-coated hemodialysis hollow fibers

To identify the advantages of 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer-coated polysulfone (PSf) hollow fibers for hemodialyzer and hemofilter minimodules with hollow fibers were made and blood compatibility was evaluated in vitro and ex vivo. Three types of hollow fibers, i.e., pure PSf (no additives), PSf alloyed with poly(1-vinyl-2-pyrrolidone) (PVPy), and PSf coated with the MPC copolymer, were processed in wet conditions. Commercially available hollow fibers (APS) were used as a control sample. The PSf hollow fibers have a condensed structure. A porous structure was observed when the PVPy was alloyed before wet processing, and no effect of the innercoated MPC copolymer on the porous structure was observed. One-tenth-sized minimodules of the conventional hemodialyzer were fabricated with 200 fibers each. The solute permeability of the hollow fibers was evaluated using 10% bovine serum in a buffer solution containing cytochrome C, which is a model protein of ₂-microglobulin. After circulation for 2.5h, the solute permeability of APS and PVPy-alloyed PSf hollow fibers decreased to 50% compared with their initial values. In contrast, the value for the hollow fibers innercoated with the MPC copolymer maintained its initial level. The inner surface of the dialysis membranes was observed with a transmission electron microscope and a layer of adsorbed protein on the PSf, APS, and PVPy-alloyed PSf hollow fibers was observed, but not on the MPC copolymer-coated fibers. Blood cell adhesion was then evaluated by circulation of whole rabbit blood without any anticoagulant ex vivo. Many adherent cells were observed on the PVPy-alloyed PSf hollow fibers; however, blood cells did not adhere or aggregate on the MPC copolymer-coated hollow fibers. From these results, we concluded that the in-situ coating of MPC copolymer on PSf hollow fibers is effective in preventing blood coagulation and maintaining the solute permeability of the fibers.