Structure and activity of insect cytokine GBP which stimulates the EGF receptor

Growth-blocking peptide (GBP) is an insect cytokine that possesses diverse biological activities such as larval growth regulation, cell proliferation, and stimulation of immune cells. GBP is a 25-amino acid peptide with one disulfide bond. It has been revealed that the tertiary structure of GBP consists of an N- and C-terminal disordered region and a well-structured core. Although there is only a slight similarity between the primary structures of GBP and EGF and the molecular weight of GBP is about half that of EGF, GBP directly binds and activates the EGF receptor of human keratinocyte cells. Furthermore, the tertiary structure of the well-defined region of GBP is similar to that of the C-terminal domain of EGF. This review will focus on the tertiary structure of GBP and its activities, as compared with those of EGF.     

Morphological studies on the bathyal ascidian,Megalodicopia hians Oka 1918 (Octacnemidae,Phlebobranchia), with remarks on feeding and tunic morphology

Megalodicopia hians Oka is a solitary ascidian belonging to the family Octacnemidae inhabiting the bathyal /abyssal zone as well as other octacnemid ascidians. The phylogenetic relationship of octacnemids is open to argument because of its extraordinary morphological features due to habitat adaptation, e.g., a pharynx lacking ciliated stigmata. Aggregations of M. hians were discovered by the manned submersible Shinkai 2000 in the bathyal seafloor of Toyama Bay, Japan Sea, in 2000; this was the first in situ observation of M. hians in the Japanese coastal waters. In 2001, a total of 36 M. hians specimens were collected from the bay (592 to approximately 978 m deep). In situ observation indicated that M. hians usually opens its large oral apertures to engulf the drifting food particles in the water current. Microscopical observation of the gut contents also showed that M. hians is a non selective macrophagous feeding on small crustaceans, diatoms, detritus, and so on. Along with the position of the intestinal loop and gonad, the morphological characteristics of the tunic (integument of ascidians) suggest that M. hians is closely related to Cionidae and/or Corellidae. Some symbiotic/parasitic organisms were occasionally found in the tunic, including rod-shaped bacteria, fungi-like multicellular structure, and spawns of unknown animals.     

Class VI myosin moves processively along actin filaments backward with large steps.

Among a superfamily of myosin, class VI myosin moves actin filaments backwards. Here we show that myosin VI moves processively on actin filaments backwards with large ( approximately 36 nm) steps, nevertheless it has an extremely short neck domain. Myosin V also moves processively with large ( approximately 36 nm) steps and it is believed that myosin V strides along the actin helical repeat with its elongated neck domain that is critical for its processive movement with large steps. Myosin VI having a short neck cannot take this scenario. We found by electron microscopy that myosin VI cooperatively binds to an actin filament at approximately 36 nm intervals in the presence of ATP, raising a hypothesis that the binding of myosin VI evokes "hot spots" on actin filaments that attract myosin heads. Myosin VI may step on these "hot spots" on actin filaments in every helical pitch, thus producing processive movement with 36 nm steps.     

Structural analysis of an insect lysozyme exhibiting catalytic efficiency at low temperatures

Bombyx mori lysozyme (BmLZ), from the silkworm, is an insect lysozyme. BmLZ has considerable activity at low temperatures and low activation energies compared with those of hen egg white lysozyme (HEWLZ), according to measurements of the temperature dependencies of relative activity (lytic and glycol chitin) and the estimation of activation energies using the Arrhenius equation. Being so active at low temperatures and low activation energies is characteristic of psychrophilic (cold-adapted) enzymes. The three-dimensional structure of BmLZ has been determined by X-ray crystallography at 2.5 A resolution. The core structure of BmLZ is similar to that of c-type lysozymes. However, BmLZ shows some distinct differences in the two exposed loops and the C-terminal region. A detailed comparison of BmLZ and HEWLZ suggests structural rationalizations for the differences in the catalytic efficiency, stability, and mode of activity between these two lysozymes.     

Association between dental health behaviours, mental/physical function and self-feeding ability among the elderly: a cross-sectional survey

Objectives : The aim of this study was to determine the association between dental health behaviour, mental/physical function and self‐feeding ability among the elderly. Subjects : A total of 414 elderly dental patients aged 65 years and older participated in this study. Methods : A survey was carried out for three years and seven months starting in January 1998 at the Chubu National Hospital. The patients or their carers were examined/interviewed about the severity of senile dementia, dental health behaviour, ability to rinse their mouths, ability to manage dentures, and ability to sit at a table during meals. To assess the association with self‐feeding ability among the elderly, cut‐offs were given for these variables, and then the odds ratios were calculated. Results : The strongest association to self‐feeding ability was marked by inability to rinse their own mouth, followed by inability to manage dentures, inability to sit at a table during meals, severe senile dementia and less frequency of toothbrushing. Conclusion : Elderly who have lost the feeding ability often could not maintain their dental health by themselves. Carers must provide not only a feeding service with acknowledgement of aspiration but oral care to prevent dental disease and fatal pneumonia in the elderly.     

Significance of venous anastomosis in fingertip replantation

Adequate venous outflow is the most important factor for successful fingertip replantation. The authors have attempted venous anastomosis in all cases of fingertip replantation to overcome postoperative congestion. In this article, the significance of venous repair for fingertip replantation is described from the authors' results of 64 complete fingertip amputations in 55 consecutive patients, which were replanted from January of 1996 to June of 2001. The overall survival rate was 86 percent. Of the 44 replantations in zone I, 37 survived, and the success rate was 84 percent. Of the 20 replantations in zone II, 18 survived, and the success rate was 90 percent. Venous anastomosis was attempted in all cases, but it was possible in 39 zone I and in all zone II replantations. For arterial repair, vein grafts were necessary in 17 of the 44 zone I and in one of the 20 zone II replantations; for venous repair, they were necessary in six zone I replantations and one zone II replantation. Postoperative vascular complications occurred in 15 replantations. There were five cases of arterial thrombosis and 10 cases of venous congestion. Venous congestion occurred in nine zone I and one zone II replantations. In five of these 10 replantations, venous anastomosis was not possible. In another five replantations, venous outflow was established at the time of surgery, but occlusion occurred subsequently. Except for the five failures resulting from arterial thrombosis, successful venous repair was possible in 49 of 59 replantations (83 percent). Despite the demand for skillful microsurgical technique and longer operation time, the authors' results using venous anastomosis in successful fingertip replantations are encouraging. By performing venous anastomosis, external bleeding can be avoided and a higher survival rate can be achieved. Venous anastomosis for fingertip replantation is a reliable and worthwhile procedure.