The role of PLK1-phosphorylated SVIL in myosin II activation and cytokinetic furrowing

Polo-like kinase 1 (PLK1) is a widely conserved serine/threonine kinase that regulates progression of multiple stages of mitosis. Although extensive studies about PLK1 functions during cell division have been performed, it is still not known how PLK1 regulates myosin II activation at the equatorial cortex and ingression of the cleavage furrow. In this report, we show that an actin/myosin-II-binding protein, supervillin (SVIL), is a substrate of PLK1. PLK1 phosphorylates Ser238 of SVIL, which can promote the localization of SVIL to the central spindle and association with PRC1. Expression of a PLK1 phosphorylation site mutant, S238A-SVIL, inhibited myosin II activation at the equatorial cortex and induced aberrant furrowing. SVIL has both actin- and myosin-II-binding regions in the N-terminus. Expression of ΔMyo-SVIL (deleted of the myosin-II-binding region), but not of ΔAct-SVIL (deleted of actin-binding region), reduced myosin II activation and caused defects in furrowing. Our study indicates a possible role of phosphorylated SVIL as a molecular link between the central spindle and the contractile ring to coordinate the activation of myosin II for the ingression of the cleavage furrow.

Increase in tumour permeability following TGF-beta type I receptor-inhibitor treatment observed by dynamic contrast-enhanced MRI

Background:

To enhance the success rate of nanocarrier-mediated chemotherapy combined with an anti-angiogenic agent, it is crucial to identify parameters for tumour vasculature that can predict a response to the treatment of the anti-angiogenic agent.

Methods:

To apply transforming growth factor (TGF)-β type I receptor (TβR-I) inhibitor, A-83-01, to combined therapy, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was carried out in mice bearing colon 26 cells using gadolinium (Gd)-DTPA and for its liposomal formulation to evaluate changes in tumour microvasculature following A-83-01. Tumour vascular parameters from DCE-MRI were compared with histological assessment and apparent diffusion coefficient of water in tumour generated by diffusion-weighted MRI.

Results:

Contrary to evaluations reported for anti-angiogenic agents, A-83-01 treatment increased the initial area under the Gd concentration–time curve (IAUGC₆₀), volume transfer constant (K^trans) and fractional plasma volume (v_p) significantly within 24 h, that was positively related to α-smooth muscle actin-positive pericyte coverage and tumour cell proliferation, and was correlated inversely with the apparent diffusion coefficient. The vascular function of the tumour improved by A-83-01 treatment was well assessed on post-liposomal Gd-DTPA-enhanced MR images, which predicted delivery of a liposomal drug to the tumour.

Conclusion:

These findings suggest that DCE-MRI and, in particular, K^trans and v_p quantitation, provide important additional information about tumour vasculature by A-83-01 treatment.

Effects of AZD2171 and vandetanib (ZD6474, Zactima) on haemodynamic variables in an SW620 human colon tumour model: an investigation using dynamic contrast-enhanced MRI and the rapid clearance blood pool contrast agent, P792 (gadomelitol)

The effect of two novel therapeutic agents on tumour haemodynamics was investigated using a fast dynamic contrast-enhanced (DCE)-MRI protocol (0.5 s/image) sensitive to signal changes in both the vascular input function and tumour during the administration of the macromolecular rapid clearance blood pool agent (MM-RCBPA), gadomelitol (P792, Vistarem). This enabled simultaneous measurement of the tumour blood flow per unit volume of tissue (F/V(T), mL/s/mL), the fractional plasma volume (V(p), %), and the permeability surface area product per unit volume of tissue (PSrho, s(-1)) in subcutaneous SW620 human colorectal tumour xenografts grown in nude rats before and after (at 0 and 22 h; imaging at 24 h) acute treatment with AZD2171 (3 mg/kg) and vandetanib (ZD6474, Zactima; 50 mg/kg), which have inhibitory activity against vascular endothelial growth factor receptor-2 (VEGFR-2) tyrosine kinase. MRI was performed at 4.7 T using a single-slice, modified, T(1)-weighted, spoiled gradient-echo technique. Both compounds reduced gadomelitol uptake into the tumour. AZD2171 and vandetanib, respectively, (a) greatly reduced PSrho to 19.7 +/- 9.5% and 28.9 +/- 14.1% of baseline (P = 0.007 and P = 0.02), (b) markedly reduced V(p) to 31.2 +/- 19.1% and 54.8 +/- 21.2% of baseline (P = 0.015 and P = 0.09), and (c) had no significant effect on F/V(T). There was no significant difference between groups treated with AZD2171 and vandetanib when each variable was compared. The reductions in PSrho and V(p) are consistent with inhibition of VEGF signalling. AZD2171 (3 mg/kg) and vandetanib (50 mg/kg) were also found to produce a comparable chronic inhibition of SW620 tumour growth (89% for both). This study shows that DCE-MRI using an MM-RCPBA can be used to distinguish tumour vascular flow, volume, and permeability surface area product in a tumour model, and enables the acute effects of VEGF signalling inhibition to be examined in detail.

Some aspects of rat femorotibial joint microanatomy as demonstrated by high-resolution magnetic resonance imaging

High-resolution magnetic resonance images (MRI) of the right femorotibial joint of normal Han:Wistar rats were acquired using a 4.7 Tesla magnet and a single-turn solenoid radio frequency coil (built in-house). Some anatomical findings of the rat femorotibial joint, which have not been reported previously using MRI, are described. The separation of patellar ligament and crural fascia was feasible on MRI. This separation would not be seen on images of lower resolution and its presence on high-resolution images could be mistaken for artefact due to the magic angle effect. Band-like fibrous structures exist in the infra-patellar fat pad, which might be mistaken as ligaments within the femorotibial joint. On sagittal MRI a vessel was seen inserted on the central part of the caudal surface of the patellar ligament. Subcutaneous fascia/cutaneous muscles (panniculus carnosus) could also be demonstrated with MRI in the femorotibial joint area.

Application of (19)F chemical shift imaging in studies of mice with orally administered 5-fluorouracil

In vivo quantitative metabolic mapping is an ideal tool for pharmacokinetic studies. Oral 5-fluorouracil (5-FU) and its metabolites in mice were imaged simultaneously by the (19)F fast spin echo (FSE) sequence using interleaved frequency selection at 9.4T. However, 5-FU images in the small intestine have never been obtained regardless of concentration. The reason for the discrepancy between image intensity and concentration was T(2). At a pH above 6, a dramatic decrease in T(2) of a (19)F 5-FU signal in an aqueous solution was found; T(2) was shorter in the small intestine (14 ms) than in the stomach (52 ms). The (19)F CSI sequence in FID sampling mode was employed for detecting short T(2) signals. With a 13-min resolution time, the detection of the 5-FU signals in the region of the small intestine (0.6 mmol/kg) was successful with a 5 x 5 mm(2) in-plane resolution. Furthermore, two signals separated by 2 ppm were clearly distinguishable, but failed to be separately detectable with the (19)F FSE sequence. For quantitative simultaneous monitoring of 5-FU and its metabolites of varying T(2), the (19)F CSI sequence in FID sampling mode was found to be superior to the (19)F FSE sequence.

Construction of two-stranded alpha-helix peptides based on influenza virus M1 protein selectively bound to RNA

Various 2alpha-helix peptides were designed and synthesized based on the RNA-binding region of matrix protein M1 in influenza virus. The binding properties of the peptides to model ssRNA, ssDNA, dsDNA, and virus RNA were examined by the fluorescence studies of a dansyl group incorporated into the peptides. The peptide containing the hydrophilic residues of M1 RNA-binding region bound RNAs selectively.

[A case of advanced breast cancer receiving combination therapy with 5'-DFUR and MPA with remarkable results]

A 75-year-old woman was admitted to our hospital with advanced breast cancer (T4bN3M0, Stage IIIb). She received chemoendocrine therapy of 5'-DFUR 800 mg/day and MPA 800 mg/ day for 2 months. The main tumor and metastatic lymph nodes were remarkably reduced and became resectable. Histological examination revealed necrotic change of the tumor tissues. This combination therapy proved very useful for advanced breast cancer.

Effect of albendazole on recurrent and residual alveolar echinococcosis of the liver after surgery

Patients with alveolar echinococcosis of the liver (AEL) can be cured by complete excision of the lesions; however, it is not always completely resectable in advanced cases. Recently, benzimidazole-type drugs have been reported to be effective in nonresectable AEL. One hundred fifty-two patients with AEL have been surgically treated in our institution since 1937. Our clinical trial with albendazole, one of the benzimidazole carbamates, has included 26 cases of AE since September 1988, each of whom had undergone an operation. Complete resection was performed in only six cases. Evaluation of response to the treatment was possible in 20 cases. A favorable response to albendazole, such as decreases in the size of the lesions, changes in cyst morphology, and amelioration in clinical symptoms or signs, was achieved in 11 (55%) cases. These favorable responses were also seen in cases of noncurative resection and palliative operation. The cumulative survival rate of the patients was 87%, 15 years after the operation. A complete response was achieved in one case; the residual lesion in the liver completely disappeared on the computed tomography image 3.5 years after noncurative surgery. Palliative or mass reduction surgery combined with albendazole therapy may be a strategy for advanced disease, especially when complete resection might result in significant morbidity or mortality.

Naloxone attenuates hypoxic depression of ganglionic transmission

The effect of the opioid antagonist naloxone on hypoxia-induced blockade of synaptic transmission in the superior cervical ganglion (SCG) of the rat was studied in vitro. Naloxone (6 X 10(-6) M or more) attenuated the hypoxia-induced blockade of synaptic transmission in the SCG. In addition, in the concentrations studied, naloxone itself had a blocking effect on ganglionic transmission that involved terminal sites of the preganglionic axons. These data suggest that the protective effect of higher doses of naloxone on the hemodynamic responses to hypoxemia or ischemia may originate at least in part from the attenuating effect of naloxone on the hypoxia-induced blockade of ganglionic transmission.

Dorsal column stimulation in man: facilitation of primary afferent depolarization

The effects of cervical epidural dorsal column stimulation on the negative and slow positive waves of the spinal cord potentials recorded from the posterior epidural space at the lumbar enlargement, in response to intense stimulation of the tibial nerve in five neurologically normal subjects during neuroleptanesthesia were studied. Single pulses applied to the cervical dorsal cord near the midline produced slow positive potentials preceded by negative waves in the dorsal spinal cord at the level of the lumbar enlargement. The negative wave, believed to represent synchronized activities of interneurons, was inhibited up to 100 to 120 msec by conditioning dorsal column stimulation. The slow positive wave, though to represent primary afferent depolarization, was facilitated for more than 100 msec with transient inhibitor for 10 to 40 msec. The results suggest that the pain-alleviating effect of dorsal column stimulation in man may be at least partly due to orthodromic and/or antidromic activation of descending inhibitory pathways which inhibit the responsible cells and facilitate primary afferent depolarization.

Interaction between human evoked electrospinograms elicited by segmental and descending volleys

Interaction between the slow negative-positive waves of human evoked electrospinograms produced by descending and segmental volleys was tested under general anaesthesia. A partial occlusion was demonstrated in these slow waves.