The metabolism of hyaluronan in cultured rabbit growth plate chondrocytes during differentiation

Hyaluronan (HA) is one of the major extracellular matrix components in cartilage. In addition to the biomechanical functions, HA has various important roles in the differentiation of chondrocytes. The purpose of this study was to clarify the nature of HA synthesis during chondrocyte differentiation. Growth plate chondrocytes were isolated from rabbit ribs and cultured in chondrocyte differentiation medium. The amount of HA and HA synthase (HAS) mRNA levels were analyzed for each stage of chondrocyte differentiation by means of high-performance liquid chromatography (HPLC) and real-time PCR, respectively. The distribution of HA in cultured chondrocytes was observed by histochemical staining. The amount of HA, ranging widely in size, was increased substantially during the hypertrophic stage. The expression levels of HAS2 and HAS3 mRNAs were low during the matrix-forming stage. HAS2 mRNA level was substantially enhanced at the pre-hypertrophic stage, whereas HAS3 mRNA level exhibited a slight increase. HAS1 mRNA was not detected. The intensity of HA staining was high around the hypertrophic chondrocytes. These results suggest that HA metabolism in chondrocyte differentiation is regulated by the selective expression of HASs, and HAS2 and the related large size-HA may have a certain association with the hypertrophic changes of chondrocytes.

[New technique to determine graft length using the proximal anastomotic system during off-pump coronary artery bypass grafting]

For determining the graft length for an aortic connector, grafts to the circumflex (Cx) and the posterior descending (PD) regions often present problems. Difficulties in determining the appropriate distance between the aorta and coronary artery have been reported to be due to changes in the morphology of the heart following the evolution of Cx and PD. We set an intermediate point (IMP) in advance and then determine graft distance in 2 steps. When using the IMP method, determination of the graft length in the Cx region is not difficult. However, attention should be paid to determine the distance between the IMP and anastomosed site without deforming the heart, as the graft length becomes shorter if the heart as a whole is pulled up by traction of the diaphragm during evolution to the PD region.

[A constrictive pericarditis on oral steroid and immunosuppressant treated with bilateral anterolateral thoracotomy; report of a case]

A successful case of pericardiectomy without median sternotomy for an immunosuppressive 59-year-old man with constrictive pericarditis (CP) was reported. He had a history of invasive thymoma, myasthenia gravis and pure red cell aplasia, and he was on oral steroid and immunosuppressant. Pericardiectomy was performed by the approach of bilateral anterolateral thoracotomy to avoid troubles due to median sternotomy under immunosuppression, and there was no postoperative infection such as mediastinitis. Bilateral anterolateral thoracotomy was considered to be useful for immunosuppressive cases.

[Beating heart coronary artery bypass grafting for acute myocardial infarction]

We consider that off-pump coronary artery bypass grafting (CABG) [OPCAB], which results in local myocardial ischemia, is more effective for patients with acute myocardial infarction (AMI) than conventional CABG under cardiac arrest with global myocardial ischemia. Twenty-one patients (15 males, 6 females) received OPCAB for AMI, among whom surgery was performed following percutaneous coronary intervention (PCI) failure in 4 and PCI was performed prior to OPCAB in 2, while PCI was not performed in the remaining 15. Preoperatively, 16 patients had intraaortic balloon pumping (IABP), and 4 had IABP and percutaneous cardiopulmonary support (PCPS). The mean interval from onset to surgery was 11.7 (range 3 to 40) hours. In 20 cases, a complete revascularization was performed. The mean number of bypasses was 2.3 and OPCAB was carried out in 14 patients. In 2 cases, OPCAB was converted to on-pump beating CABG for complete revascularization. Fourteen patients (67%), each maintained with preoperative left ventricular ejection fraction (EF), were discharged with an elective bypass. Four patients died after on-pump beating CABG, in whom EF was lower than 10%. In addition, 3 died of low cardiac output syndrome (LOS) under PCPS and 1 of ventricular fibrillation. Based on our results, we considered that complete revascularization using OPCAB was effective for cases of AMI with PCI difficulty. However, in shock cases requiring PCPS, cardiac function was not improved even after revascularization. Therefore, it is necessary to study new procedures for shock cases during the period from onset to surgery.

Neural substrates of the performance of an auditory verbal memory: between-subjects analysis by fMRI

We studied the neural correlates for the performance of auditory verbal memory using fMRI in 28 normal right-handed volunteers who had to encode and retrieve 50 related word-pair associates. Since the effectiveness of encoding and retrieval processes contribute to memory performance, we combined them in one analysis in addition to examining each condition. Between-subjects analyses were performed by a two-sample t-test in which brain activation in the good-performance group was compared with that of the poor-performance group. Regression analysis was also carried out to find the regions whose activations were linearly correlated to the number of correct recalls by all subjects. In addition to the positive correlates of memory performance, the areas whose activations have a negative effect were also examined. The results indicate that the brain networks of positive correlates including the parahippocampal gyrus and negative correlates including the right prefrontal cortex constitute neural substrates for the performance of auditory verbal memory.

[Oral sildenafil citrate as an effective alternate in the treatment of postoperative pulmonary hypertensive crisis after congenital heart surgery]

A five-month-old girl of Down syndrome underwent a corrective surgery for complete atrioventricular septal defect. Her postoperative course was complicated with pulmonary hypertensive (PH) crises despite nitroglycerin (NTG) infusion and inhaled nitric oxide (NO). Sildenafil citrate, a phosphodiesterase 5 inhibitor, was administered through a nasogastric tube at a starting dose of 0.3 mg/kg by stepwise increment to the maximum dose of 2 mg/kg 4 hourly. Sildenafil citrate dramatically lowered pulmonary arterial pressure and the patient was weaned from NTG and NO without PH crisis. There was no side effect after sildenafil citrate administration. Oral sildenafil citrate is a safe and potent adjunct to the existing therapies for postoperative PH in infants after open heart surgery.

Effects of TGF-beta on hyaluronan anabolism in fibroblasts derived from the synovial membrane of the rabbit temporomandibular joint

Hyaluronan (HA) synthesis in the synovial membrane is affected by various chemical mediators. It is hypothesized that transforming growth factor-beta 1 (TGF-beta 1) would be a mediator to modulate HA synthesis in cultured synovial membrane fibroblasts of the temporomandibular joint (TMJ). Fibroblasts were extracted from the TMJ synovial membrane of four-week-old Japanese white rabbits. The amount of HA and expression levels of HA synthase (HAS) mRNAs induced by TGF-beta 1 treatment were analyzed by means of high-performance liquid chromatography and real-time polymerase chain-reaction, respectively. Both medium and large amounts of HA were enhanced by the stimulation of TGF-beta 1. HAS2 mRNA expression was enhanced 13-fold after six-hour stimulation with TGF-beta 1 (10 ng/mL), whereas HAS3 mRNA expression was not changed significantly. These results suggest that TGF-beta 1 enhances the expression of HAS2 mRNA in the TMJ synovial membrane fibroblasts and may contribute to the production of high-molecular-weight HA in the joint fluid.

Decrease in cortical benzodiazepine receptors in symptomatic patients with leukoaraiosis: a positron emission tomography study

BACKGROUND AND PURPOSE

[11C]flumazenil (FMZ), a ligand that selectively binds to the central benzodiazepine receptor in the neuronal membrane, is useful for evaluating neuronal viability in a positron emission tomography (PET) scan. Using this ligand, we investigated whether there was a correlation between neuronal integrity in various brain structures and dementia in patients with leukoaraiosis.

METHODS

Twelve patients with extensive leukoaraiosis on magnetic resonance imaging were divided into groups of patients with or without dementia. Based on a 2-compartment, 2-parameter model that included metabolite-corrected arterial input and PET-measured cerebral radioactivity, the distribution volume of FMZ (FMZ-V(d)) was calculated in various regions of interest by nonlinear curve fitting. Additionally, tracer kinetic analysis was applied for voxel-by-voxel quantification of FMZ-V(d), and data analysis was performed by statistical parametric mapping.

RESULTS

The presence of dementia was associated with a reduced FMZ-V(d) in widespread areas of the cerebral cortex, including the bilateral frontopolar and frontal/insular areas, the left temporo-occipital border areas, and the left marginal cortical areas.

CONCLUSIONS

Differences in neuronal integrity in the cerebral cortex might determine whether patients with leukoaraiosis become symptomatic or not.

Granular cell tumor occurring in the sigmoid colon treated by endoscopic mucosal resection using a transparent cap (EMR-C)

A case of granular cell tumor occurring in the sigmoid colon is reported. The patient, a 56-year-old man, visited our hospital for further evaluation of occult blood in his stool. Endoscopic examination revealed a yellowish, hemispheric submucosal tumor (SMT) with redness, about 6 mm in diameter, in the sigmoid colon. Endoscopic mucosal resection using a transparent cap (EMR-C) was performed, and histological examination revealed that the tumor consisted of a nested growth of large tumor cells with ample granular cytoplasm and small round nuclei. The tumor cells expressed S-100 protein and were stained with neuron-specific enolase (NSE) and periodic acid-Schiff, but were negative for desmin, vimentin, and cytokeratin. The resected tumor was diagnosed as a granular cell tumor. This may be the first report of a colorectal granular cell tumor successfully treated with EMR-C.

Efficacy and safety profile of S-1 in patients with metastatic gastric cancer in clinical practice: results from a post-marketing survey

BACKGROUND

S-1(TS-1), a novel oral fluoropyrimidine, has been commercially available for gastric cancer in Japan. A nationwide post-marketing survey for safety was carried out after its approval. The aim of this analysis was to evaluate the efficacy and safety profile of this agent in clinical practice for patients with advanced gastric cancer registered in the postmarketing survey from our institution.

METHODS

Between April 1999 and April 2000, a total of 51 chemo-naive patients were registered in the survey from the National Cancer Center Hospital East. S-1 was administered at 80 mg/m2/day for 4 weeks, followed by a 2-week rest, repeated every 6 weeks until disease progression, unacceptable toxicity, or the patient's refusal.

RESULTS

Of the 51 patients, 41 (80%) fulfilled the criteria of the guidelines determined by the company as appropriate patients for the drug administration. The median number of treatment courses was five. Toxicities were generally mild: grade 3 or 4 toxicities were seen in 10% or fewer patients, and no treatment-related deaths occurred. In the 47 patients with evaluable lesions, there were 2 complete responses and 18 partial responses, with a response rate of 43%. With a minimum follow-up of 2 years, median survival time and 2-year survival were 11.1 months and 33%, respectively. The majority of the 17 2-year survivors had diffuse-type histology and peritoneal metastasis and achieved an objective response.

CONCLUSION

S-1 appears to be safe and highly active, with favorable longterm survival in patients with metastatic gastric cancer, particularly in those with diffuse-type histology and peritoneal metastasis.

Mechanical stimuli enhances the expression of RGD-CAP/betaig-h3 in the periodontal ligament

RGD-CAP, a member of the fasciclin family, is expressed in the periodontal ligament (PDL). Since the PDL is continually subjected to mechanical forces from such orofacial functions as mastication, biting, speech and swallowing, the mechanical stimuli is thought to be associated with the expression of RGD-CAP. Furthermore, the adhesive functions of RGD-CAP may contribute to the maintenance or regeneration of PDL architecture. The objective of this study was to examine whether mechanical stimuli modulate the expression of RGD-CAP in the human PDL, and to examine the effects of recombinant RGD-CAP on the adhesion of PDL cells. During experimental tooth movement, the expression of RGD-CAP was significantly enhanced in the PDL. In vitro experiments with cultured PDL cells showed that the expression of RGD-CAP mRNA was significantly enhanced by mechanical tensile force of 15.4kPa for 48h. The induction of RGD-CAP mRNA, meanwhile, was completely inhibited by cycloheximide which is an inhibitor of protein synthesis. Furthermore, neutralising antibody against TGF-beta also suppressed the mechanical induction of RGD-CAP. The adhesion of cultured PDL cells onto plates coated with recombinant RGD-CAP increased significantly compared with the controls. These findings suggest that RGD-CAP, induced by TGF-beta expressed in response to mechanical stimuli, plays an important role in modulating the homeostasis of PDL.

EMR as salvage treatment for patients with locoregional failure of definitive chemoradiotherapy for esophageal cancer

BACKGROUND

Definitive chemoradiotherapy is recognized as a standard treatment for esophageal cancer. Although most failures of this combined modality are locoregional, without distant metastasis, there are few curative treatment options available in such cases except salvage esophagectomy.

METHODS

Experience with 16 patients with squamous cell carcinoma of the esophagus who underwent EMR as a salvage treatment after locoregional failure of definitive chemoradiotherapy was reviewed retrospectively. EMR was performed by using the mucosal strip technique. Eight patients had local recurrence at the primary site after a complete response to chemoradiotherapy, 5 had metachronous multiple cancers, and 3 had residual tumor after completing chemoradiotherapy.

RESULTS

In all patients, the EMR-treated tumors were histopathologic stage T1 and were clinical stage N0M0 as defined by EUS and CT. No serious complication was observed in any patient. At a median follow-up of 33 months (range 11-73 months) from the initiation of chemoradiotherapy, 3 patients (38%) with local recurrence at the primary site, 3 (40%) with metachronous multiple cancers, and two (67%) with residual cancer were still alive and disease-free after salvage EMR, for periods of 30 to 63 months. The 3-year survival rate from the initiation of salvage EMR for all patients was 56%.

CONCLUSIONS

Long-term survival can be achieved with salvage EMR for locoregional failure after definitive chemoradiotherapy for esophageal cancer without serious complications. EMR may be a salvage treatment option when a recurrent or residual tumor is superficial or local.

Strong static magnetic field and the induction of mutations through elevated production of reactive oxygen species in Escherichia coli soxR

PURPOSE

Although strong static magnetic fields (SMF) are supposed to have the potential to affect biological systems, the effects have not been evaluated sufficiently. Experiments should be performed with a powerful SMF-generating apparatus to evaluate the biological effects of SMF.

MATERIALS AND METHODS

An Escherichia coli mutation assay was used to assess the mutagenic effects of strong SMF. Various mutant strains of E. coli were exposed to up to 9 Tesla (T) for 24 h and the frequencies of rifampicin-resistant mutations were then determined. The expression of the soxS::lacZ fusion gene was assessed by measurement of beta-galactosidase activity.

RESULTS

The results for survival or mutation were obtained with wild-type E. coli strain GC4468 and its derivatives defective in DNA repair enzymes or redox-regulating enzymes were all negative. On the other hand, the mutation frequency was significantly increased by the SMF exposure in soxR and sodAsodB mutants, which are defective in defence mechanisms against oxidative stress. Furthermore, the expression of superoxide-inducible soxS::lacZ fusion gene was stimulated 1.4- and 1.8-fold in E. coli when exposed to 5 and 9 T, respectively.

CONCLUSIONS

These results indicate that strong SMF induce mutations through elevated production of intracellular superoxide radicals in E. coli.