Up-regulation of VGLUT2 expression in hypothalamic-neurohypophysial neurons of the rat following osmotic challenge

A second vesicular glutamate transporter (VGLUT2) has been reported to be expressed in neurosecretory neurons of the hypothalamic-neurohypophysial system. To study its role in the neurosecretory neurons, we evaluated the expression of the VGLUT2 gene in the paraventricular (PVN) and supraoptic (SON) nuclei as well as the immunoreactivity in the neurohypophysis under euhydrated and chronic hyperosmotic conditions with in situ hybridization and immunohistochemistry. The intensity of hybridization signals in the PVN, SON and thalamus of rats subjected to water deprivation for 7 days, or drinking 2% NaCl for 4 or 7 days, was compared with that of euhydrated rats (control). The overall intensity in the entire PVN or SON, but not the thalamus, was higher in osmotically stimulated rats than in controls. Within the PVN, a significantly higher intensity of signals than that of controls was found only in the dorsolateral posterior magnocellular region in 4-day salt-loaded rats and in all subregions in water-deprived or 7-day salt-loaded rats. The intensity in the SON was higher in the stimulated rats than in controls, regardless of subregions. In the neurohypophysis, VGLUT2 staining was frequently localized in vasopressin terminals of control rats and was apparently reduced in stimulated rats. These results indicate that VGLUT2 is principally expressed in magnocellular vasopressin neurons, suggesting some local effect of intrinsic glutamate on neurohypophysial hormone secretion.     

Non-gated fetal MRI of umbilical blood flow in an acardiac twin

Currently, the standard method of diagnosis of twin reversed arterial perfusion (TRAP) sequence is ultrasound imaging. The use of MRI for flow visualization may be a useful adjunct to US imaging for assessing the presence of retrograde blood flow in the acardiac fetus and/or umbilical artery. The technical challenge in fetal MRI flow imaging, however, is that fetal electrocardiogram (ECG) monitoring required for flow imaging is currently unavailable in the MRI scanner. A non-gated MRI flow imaging technique that requires no ECG monitoring was developed using the t-test to detect blood flow in 20 slices of phase-contrast MRI images randomly scanned at the same location over multiple cardiac cycles. A feasibility study was performed in a 24-week acardiac twin that showed no umbilical flow sonographically. Non-gated MRI flow images clearly indicated the presence of blood flow in the umbilical artery to the acardiac twin; however, there was no blood flow beyond the abdomen. This study leads us to conjecture that non-gated MRI flow imaging is sensitive in detecting low-range blood flow velocity and can be an adjunct to Doppler US imaging.     

Role of Ser50 phosphorylation in SCG10 regulation of microtubule depolymerization

Members of the stathmin-like protein family depolymerize microtubules (MTs), probably due to the ability of each stathmin monomer to bind two tubulin heterodimers in a complex (T(2)S complex). SCG10, a member of this family, is localized in the growth cone of neurons. It has four identified sites of serine phosphorylation (S50, S63, S73, and S97). Of these, S50 and S97 are phosphorylated by cAMP-dependent protein kinase, an enzyme involved in growth cone guidance. When the equivalent sites in stathmins are phosphorylated, they lose their ability to depolymerize MTs. We investigated the specific role of the two cAMP-dependent protein kinase (PKA) phosphorylation sites in SCG10. A mutant of SCG10 phosphorylated only on S50 retained the ability to depolymerize MTs, but SCG10 phosphorylated on S97 or on both S50 and S97 lost MT-depolymerizing activity. Surface plasmon resonance studies revealed that the phosphorylation of SCG10 at these sites reduced the tubulin heterodimer binding, mainly due to a reduced rate of association. In particular, compared to the two other phosphorylated forms, SCG10 phosphorylated at S50 had a significantly smaller dissociation constant for the binding of the first tubulin heterodimer and larger association and dissociation rate constants for the binding of the second heterodimer. This indicates that the phosphorylation of S50 compensates for the effect of phosphorylation at other sites by modulating T2S complex formation. Furthermore, these results suggest that S50-P maintains MT-depolymerizing activity, which indicates that the biological functions of phosphorylation at S50 and S97 are different.     

Adrenocorticotropic hormone is produced in the ventricle of patients with essential hypertension

OBJECTIVE: Aldosterone is produced in the ventricle of patients with hypertension. The present study was designed to examine whether adrenocorticotropic hormone (ACTH) and cortisol are also produced from the heart in patients with essential hypertension. METHODS: The study population consisted of 57 patients with essential hypertension and 28 control subjects. Plasma levels of ACTH, aldosterone, and cortisol were measured in the aortic root, the anterior interventricular vein and the coronary sinus during cardiac catheterization. RESULTS: The plasma levels of ACTH were significantly higher at the anterior interventricular vein and coronary sinus than at the aortic root (12.7 +/- 1.0 versus 10.7 +/- 0.9 pmol/l, P < 0.001; and 12.3 +/- 1.0 versus 10.7 +/- 0.9 pmol/l, P < 0.001, respectively) in the hypertension group, whereas there were no significant differences in the levels among these sites in the control group. The plasma levels of aldosterone were significantly higher at the anterior interventricular vein and the coronary sinus than at the aortic root (261.7 +/- 16.4 versus 239.1 +/- 15.1 pmol/l, P < 0.001; and 258.8 +/- 17.0 versus 239.1 +/- 15.1 pmol/l, P < 0.01, respectively) in the hypertension group, whereas there were no significant differences in the levels among these sites in the control group. CONCLUSIONS: ACTH as well as aldosterone is produced, but cortisol is not produced, from the ventricle of patients with essential hypertension.     

Study of the usefulness of large intestine screening inspections using multi-slice CT (MSCT)

CT-colonography (CT-C), a new diagnostic imaging technique for cancer of the large intestine--which is increasing rapidly owing to westernized eating habits--has advanced from the developmental stage to the stage of practical application, thanks to progress in MSCT and workstation development. Therefore, based on the results of CT-C application using 16 lines of MSCT to a screening test, we reviewed the usefulness of CT-C in our clinic. We supplemented defective depiction, and found that change of position was effective for virtual image exclusion. We consider that CT-C can support diagnosis if the target of screening tests is a polypoid lesion of more than 6 mm. In addition, it is expected that the number of examinations performed during office visits will increase because of the decreased invasiveness of the procedure, its lack of pain, and its ability to provide early lesion detection.     

Studies on protocadherin-2 expression in the human fetal central nervous system

Protocadherin (Pcad) is a group of molecules obtained by polymerase chain reaction (PCR) utilizing the sequence that is well preserved in the extracellular domain of cadherin. Sano et al. analyzed Pcad (PC42,43) that had been cloned from rats, and found that it basically had homology to cadherin, but contained more than six cadherin repeats with a completely different intracellular domains (Sano et al. 1993). In the present study, of the Pcad (Pcad-1,2) cloned from a human cDNA library, as-yet-unspecified Pcad-2 was analyzed for expression in the human fetal central nervous system (CNS). Northern blot analysis of adult human tissue showed that Pcad-2 was expressed in the brain and the placenta, and that Pcad-2 mRNA was expressed in actively dividing neural tumor cell lines. Monoclonal antibodies against Pcad-2 were then made, and the CNS of fetuses were immunohistochemically stained. The expression was hardly visible at the 6th week of pregnancy, and began to become visible along the nerve fiber in the brain stem at the 8th week, and spread over the entire brain at the 11th week. At the 18th week, however, expression in the nerve fascicles, which had been visible by that time, was no longer visible or had decreased. These results suggest that Pcad-2 appears relatively early in the critical stage of development of the fetal CNS, and is involved in the induction, fasciculation, and extension of axons.     

Laparoscopic distal pancreatectomy as the total biopsy of the pancreas: tool of minimally invasive surgery

Because of recent progress in imaging modalities, the opportunities to detect pancreatic cystic neoplasms are increasing. However, serous cystadenoma is still uncommon. We report a case of serous cystadenoma treated by laparoscopic distal pancreatectomy. A 52-year-old woman presented with mild upper abdominal pain. Dynamic computed tomography (CT) revealed a solitary cystic lesion 3cm in diameter in the pancreatic tail. Endoscopic ultrasound showed a honeycomb pattern, indicative of serous cystadenoma. To obtain the final diagnosis of the tumor, we performed laparoscopic distal pancreatectomy. A histopathological study showed microcystadenoma with no evidence of malignancy.     

Antiaggregatory activity in human platelets of potent antagonists of the P2Y 1 receptor

Activation of the P2Y(1) nucleotide receptor in platelets by ADP causes changes in shape and aggregation, mediated by activation of phospholipase C (PLC). Recently, MRS2500(2-iodo-N(6)-methyl-(N)-methanocarba-2'-deoxyadenosine-3',5'-bisphosphate) was introduced as a highly potent and selective antagonist for this receptor. We have studied the actions of MRS2500 in human platelets and compared these effects with the effects of two acyclic nucleotide analogues, a bisphosphate MRS2298 and a bisphosphonate derivative MRS2496, which act as P2Y(1) receptor antagonists, although less potently than MRS2500. Improved synthetic methods for MRS2500 and MRS2496 were devised. The bisphosphonate is predicted to be more stable in general in biological systems than phosphate antagonists due to the non-hydrolyzable CP bond. MRS2500 inhibited the ADP-induced aggregation of human platelets with an IC(50) value of 0.95 nM. MRS2298 and MRS2496 also both inhibited the ADP-induced aggregation of human platelets with IC(50) values of 62.8 nM and 1.5 microM, respectively. A similar order of potency was observed for the three antagonists in binding to the recombinant human P2Y(1) receptor and in inhibition of ADP-induced shape change and ADP-induced rise in intracellular Ca(2+). No substantial antagonism of the pathway linked to the inhibition of cyclic AMP was observed for the nucleotide derivatives, indicating no interaction of these three P2Y(1) receptor antagonists with the proaggregatory P2Y(12) receptor, which is also activated by ADP. Thus, all three of the bisphosphate derivatives are highly selective antagonists of the platelet P2Y(1) receptor, and MRS2500 is the most potent such antagonist yet reported.