Regucalcin increases superoxide dismutase activity in the heart cytosol of normal and regucalcin transgenic rats

The effect of regucalcin, a regulatory protein in the intracellular signaling system, on superoxide dismutase (SOD) activity in the heart cytosol of normal rats and regucalcin transgenic (TG) rats was investigated. The addition of regucalcin (10(-10) to 10(-8) M) with a physiologic concentration in the enzyme reaction mixture containing the heart cytosol obtained from normal rats caused a significant increase in SOD activity, indicating that regucalcin directly activates the enzyme. The effect of regucalcin (10(-8) M) in increasing SOD activity was not seen in the presence of dithiothreitol (DTT; 0.1 or 1.0 mM), a protecting reagent for sulfhydryl group, or N-ethylmaleimide (NEM; 0.1 or 1.0 mM), a modifying reagent for sulfhydryl group, in the reaction mixture, indicating that regucalcin does not affect the sulfhydryl group. The addition of zinc sulfate (10(-6) to 10(-4) M) in the reaction mixture did not cause a significant change in SOD activity, while the enzyme activity was markedly decreased in the presence of cupric sulfate (10(-6) to 10(-4) M). The activatory effect of regucalcin (10(-8) M) on SOD was seen in the presence of zinc (10(-4) M), while not observed in the presence of copper (10(-4) M). Moreover, SOD activity was significantly enhanced in the heart cytosol of regucalcin TG rats as compared with that of normal rats. This study demonstrates that regucalcin increases SOD activity in the heart cytosol of rats, and that its effect is not related to the sulfhydryl group of enzymes.     

Hyperlipidemia is induced in regucalcin transgenic rats with increasing age

Regucalcin plays an important role as a regulatory protein in intracellular signaling pathway in many cells. Regucalcin transgenic (TG) rats have been shown to induce a remarkable increase in serum triglyceride and HDL-cholesterol concentrations at the age of 36 weeks (35). Furthermore, this was investigated in regucalcin TG rats with increasing age (14, 25, 36 or 50 weeks). Serum triglyceride or HDL-cholesterol concentration was markedly increased in regucalcin TG male and female rats at 14, 25, 36 or 50 weeks of age. Serum-free fatty acid concentration was significantly elevated in regucalcin TG male and female rats at 25, 36 or 50 weeks. In the TG female rats, a significant increase in serum free fatty acid concentration was also observed at 14 weeks of age, while it was not seen in the TG male rats. Serum-free cholesterol concentration was significantly increased in regucalcin TG female rats at 14, 25, 36 or 50 weeks. Such an increase was not induced in the TG male rats. Moreover, serum calcium concentration was significantly raised in regucalcin TG male and female rats at 50 weeks of age. Also, serum albumin concentration was significantly elevated in regucalcin TG female rats at 25, 36, or 50 weeks of age. Such an increase was not observed in the TG male rats. Serum zinc, glucose or urea nitrogen concentration was not significantly altered in TG male and female rats. This study demonstrates that hyperlipidemia is uniquely induced in regucalcin TG rats with increasing age.     

Optical mapping of pontine chemosensitive regions of neonatal rat

We analyzed the neuronal response to hypercapnic acidosis, using an optical recording technique with a fluorescent voltage-sensitive dye (di-4-ANEPPS), in pontine slice preparations of neonatal rats, containing the locus coeruleus (LC), which has been electrophysiologically demonstrated to be chemosensitive. The dye-stained preparation was continuously superfused with artificial cerebrospinal fluid. Epifluorescence of the slice was detected using a high-sensitivity optical recording system. Changes in the intensity of fluorescence were serially analyzed while switching artificial cerebrospinal fluid from control to hypercapnic acidosis, or vice versa. The optical recording method revealed that the LC, as reported in previous studies, reversibly showed a depolarizing response to hypercapnic acidosis in 56% of the examined preparations. The A5 area (56%) also exhibited a reversible, depolarizing response to hypercapnic acidosis. The response was preserved under conditions in which chemical synaptic transmission was blocked by low Ca(2+)-high Mg(2+) solution. These results suggest that the optical recording method is applicable to identification of potentially chemosensitive areas, which deserve further electrophysiological analysis, and that the A5 area could be chemosensitive.     

Premature regression of the leg apical ectodermal ridge in the Japanese chick wingless mutant

The autosomal dominant Japanese wingless mutant has varying degrees of wing and leg truncations. The wing defects range from complete loss to negligible defects, whereas leg abnormalities are usually restricted to loss of the phalanges. Further analyses of the mutant focusing on the leg, which has been relatively uncharacterized, were performed. The expression pattern of Fgf8, a marker gene for the apical ectodermal ridge (AER) that controls outgrowth of the limbs, revealed premature regression at stage 28. Electron microscopy study showed abnormalities in the basement membrane all through the AER in the same stage. In the mutant, cell death was observed in the mesenchyme underlying AER between stages 31 and 32, although in the wild-type leg, AER regression and cell death occurred almost simultaneously at stages 33–34. To know if the cell death and cessation of the outgrowth are common mechanisms of wild-type and the mutant, we removed the AER in wild-type embryos at stage 28 and followed the fate of the limb. This also resulted in premature cell death 48 h after AER removal (equivalent to stage 32) and limb truncations similar to those observed in mutant limbs. To confirm whether either AER or underlying mesenchyme is responsible for the truncation, transplantation of the AER between the wild-type and the mutant was performed. This revealed that AER is the defective tissue in this mutant.     

Relationship between cochlear implant outcome and the diameter of the cochlear nerve depicted on MRI

This study aimed to evaluate the relationship between the diameters of the auditory and eighth cranial nerves and improvements in post-implant performance. Twenty prelingually deafened children (aged from 2.0 to 6.0 years) who received the Nucleus 24 cochlear implant participated in this study. All subjects had used their implant for at least 1 year after device connection. The diameters of cochlear and eighth cranial nerves were retrospectively measured on preoperative T2-weighted axial magnetic resonance image (MRI). In 17 of 20 subjects, the cochlear and eighth cranial nerves could be identified on MRI. The mean diameter of the cochlear and eighth cranial nerves were 0.9 +/- 0.2 mm and 1.2 +/- 0.3 mm, respectively. In the remaining three subjects, the cochlear and eighth cranial nerves could not be identified on MRI. These three subjects had significantly lower scores in the Infant-Toddler-Meaningful Auditory Integration Scale (IT-MAIS) than the other 17 subjects at 12 months post-implant. There was no significant correlation among the maximal diameters of the nerves and age, ECAP thresholds and IT-MAIS scores. A sufficient outcome from cochlear implantation can be expected when cochlear and eighth cranial nerves are depicted on MRI, regardless of the nerve diameters.     

Rapidly prototyped temporal bone model for otological education

The anatomy of the temporal bone is extremely complicated. If a three-dimensional model could be simulated, it would greatly contribute to the stereoscopic understanding of anatomy and surgery. A simulated three-dimensional model of a human temporal bone was prototyped using the selective laser sintering method. The model could be shaved using a surgical drill in the same way as in real surgery. A magnified model was particularly useful for the instruction of anatomy and surgery. When a translucent area was selected, a bony labyrinth could be created together with an internal auditory meatus and facial nerve, which also contributed to the easy understanding of the inner ear structure. The three-dimensional prototyped model using selective laser sintering serves as a good educational material for middle ear anatomy and surgery.     

Imaging of acute pancreatitis--the role of US, CT and MRI

Imaging of the pancreas with US and CT plays a major role in the diagnosis and evaluations of patients with acute pancreatitis. In severe acute pancreatitis, dynamic CT is essential to assess the severity of the disease and evaluate the complications. MRI is comparable to CT in its capacity to provide precise information about the severity of acute pancreatitis. MRI has some advantages over CT in being free from ionizing radiation and lower toxity of gadolinium which is used for contrast medium intravenously. The disadvantages of MRI, however, include cost, longer exam duration, limited availability and the practical difficulties of scanning a patient with ICU equipment.