Polymerization of ethylene with Cr[OC(CH3)3]4/Al(C2H5)2Cl as catalyst modified with some metal chlorides

Polymerization of ethylene was carried out in toluene using the homogeneous catalytic system Cr[OC(CH₃)₃]₄/Al(C₂H₅)₂Cl, combined with various metal chlorides (MtCl_x). The polymerization activity was found to be strongly dependent upon the MtCl_x used. A clear correlation was found between the activity and the elctronegativity X(Mt^x+) of the metal ion in MtCl_x. MtCl_x containing metal ions with X(Mt^x+) < 8,5 (electronegativity of the active Cr²⁺) show a markedly increased activity, whereas those with X(Mt^x+) > 8,5 have a rather decreased activity. Thus, for example, the catalyst combined with MgCl₂ shows very high activity to give a linear polyethylene with a remarkably high molecular weight and narrow molecular weight distribution. A plausible mechanism for the enhancement of the activity by suitable MtCl_x is proposed on the basis of these results.     

Effect of monomer diffusion in the polymerization of olefins over Ziegler-Natta catalysts

By using an extremely high stereospecific catalyst, three kinds of copolymerizations were carried out with combinations of monomers which differ in the crystallinity of the homopolymers. Addition of a small quantity of comonomer to the homopolymerization systems producing very high crystalline polymers was found to cause a remarkable increase in the apparent polymerization rate as well as a marked decrease in the polymer crystallinity. Such an irregular increase in the polymerization activity was, however, not observed when a small amount of comonomer was added to the homopolymerization systems producing low-crystalline or amorphous polymers. These observations have led to the conclusion that resistance of monomer diffusion through the polymer film should be one of the significant parameters for the apparent polymerization rate when very high crystalline polymers, like high density polyethylene, isotactic polypropylene etc., are produced.     

The efferent blood flow of early hepatocellular carcinoma and borderline lesions: Demonstration by color Doppler imaging

We performed waveform analysis of the efferent signal detected within early hepatocellular carcinomas and borderline lesions, in which portal flow was demonstrated. Continuity of this flow with the surrounding vessels was also analyzed. Nine nodules in 7 patients with early hepatocellular carcinomas and borderline lesions were included in this study. Tumor diameter ranged from 1.2 to 3.5 cm; average, 2.1 cm. Waveform of the efferent flow signal from within these nodules was continuous in 5 nodules and biphasic venous in 4 nodules. Outside the nodules, the waveform of the efferent flow signal was that of a biphasic venous wave. All efferent signals were confirmed to continue in the hepatic vein. These findings thus suggest that the draining vessel in early hepatocellular carcinomas and their borderline lesions is the hepatic vein.     

Expression of sphingosine kinase 2 in synovial fibroblasts of rheumatoid arthritis contributing to apoptosis by a sphingosine analogue, FTY720

Gene expression profiles in synovial tissues from rheumatoid arthritis (RA) patients have yielded useful information on the pathogenetic process of the synovitis. In one group of them, sphingosine kinase 2 (SPHK2), a nuclear protein regulating cell proliferation, seemed to be highly expressed, undergoing a different pathogenetic process of synovitis. In the present study it was clarified that SPHK2 was expressed in the synovial fibroblasts of the synovial tissues obtained from the knee joints of the RA patients. In the cultured synovial fibroblasts from these patients, SPHK2 was more highly expressed than that in the human macrophage cell line, THP-1 and human dermal fibroblasts. SPHK2 was expressed in and around the nucleus and transferred to the cytoplasm and cell surface by the administration of epidermal growth factor, associated with the increased expression of sphingosine-1-phosphate. A sphingosine analogue, FTY720, which is activated by phosphorylation specifically by SPHK2, mediated apoptotic signaling of the cultured synovial fibroblasts. These findings suggest that SPHK2 may regulate the autonomous proliferation of synovial fibroblasts as one of the predisposing genes to RA and could be a target for a novel therapeutic strategy for RA.     

Mitral annuloplasty as a ventricular restoration method for the failing left ventricle: a pilot study

BACKGROUND AND AIM OF THE STUDY: Undersized mitral annuloplasty (MAP) is effective in patients with dilated cardiomyopathy and functional mitral regurgitation (MR) since, as well as addressing the MR, the MAP may also reshape the dilated left ventricular (LV) base. However, the direct benefits of this possible reshaping on LV function in the absence of underlying MR remain incompletely understood. The study aim was to identify these benefits in a canine model of acute heart failure. METHODS: Six dogs underwent MAP with a prosthetic band on the posterior mitral annulus, using four mattress sutures. The sutures were passed individually through four tourniquets and exteriorized untied via the left atriotomy. Sonomicrometry crystals were implanted around the mitral annulus and left ventricle to measure geometry and regional function. Acute heart failure was induced by propranolol and volume loading after weaning from cardiopulmonary bypass; an absence of MR was confirmed by echocardiography. MAP was accomplished by cinching the tourniquets. Data were acquired at baseline, after induction of acute heart failure, and after MAP. RESULTS: MAP decreased mitral annular dimensions in both commissure-commissure and septal-lateral directions. Concomitantly, the diastolic diameter of the LV base and LV sphericity decreased (i.e., improved) from 37.4 +/- 9.3 to 35.9 +/- 10 mm (p = 0.063), and from 67.9 +/- 18.6% to 65.3 +/- 18.9% (p = 0.016), respectively. Decreases were evident in both LV end-diastolic pressure (from 17 +/- 7 to 15 +/- 6 mmHg, p = 0.0480 and Tau (from 48 +/- 8 to 45 +/- 8 ms, p <0.01), while fractional shortening at the LV base increased from 7.7 +/- 4.5% to 9.4 +/- 4.5% (p = 0.045). After MAP, increases were identified in both cardiac output (from 1.54 +/- 0.57 to 1.65 +/- 0.57 1/min) and Emax (from 1.86 +/- 0.9 to 2.41 +/- 1.31 mmHg/ml). CONCLUSION: The data acquired suggest that isolated MAP may have certain benefits on LV dimension/function in acute heart failure, even in the absence of MR. However, further investigations are warranted in a model of chronic heart failure.     

Influence of nasal resistance on initial acceptance of continuous positive airway pressure in treatment for obstructive sleep apnea syndrome

BACKGROUND: Continuous positive airway pressure (CPAP) is considered as the standard therapy for obstructive sleep apnea syndrome (OSAS), but some patients with OSAS are unable to accept CPAP due to nasal obstruction and poor nasal airflow. OBJECTIVES: We assessed the influence of nasal resistance before beginning CPAP treatment on the initial acceptance of CPAP in OSAS patients. METHODS: The study subjects comprised 77 patients (74 males, 3 females) with primary OSAS, all of whom received CPAP treatment with nasal masks. Before trials, all subjects underwent overnight polysomnography, and nasal resistance was measured with active anterior rhinomanometry in the seated position on the first day of CPAP trial. RESULTS: The CPAP treatment was accepted by 56 patients after the initial trials with overnight polysomnography. Body mass index, the number of apnea/hypopnea episodes per hour (apnea/hypopnea index; AHI), and the number of episodes per hour with an oxygen desaturation of >3% (oxygen desaturation index) were significantly higher (p<0.01) and nasal resistance was lower (p=0.003) in patients who accepted CPAP than in those who did not. Logistic regression analysis, with patient age, body mass index, Epworth sleepiness scale score, AHI, oxygen desaturation index, and nasal resistance before CPAP treatment as explanatory variables, showed that nasal resistance (OR+0.1 Pa/cm3/s: 1.48; p=0.002) and AHI (OR+1 event/h: 0.93; p=0.003) were significant factors for CPAP non-acceptance. CONCLUSIONS: Nasal resistance before the beginning of CPAP treatment has a significant effect on the acceptance of CPAP in OSAS patients, and hence, could be a predictive parameter for the initial acceptance of CPAP.     

How to make sure a balloon-type gastrostomy replacement was made right by ultrasound

With the spread of gastric fistula, there have been increased reports of catheter aberrant and fistula damage during the time of catheter exchange procedures. Therefore, it has been recommended that a diagnostic imaging or endoscopic gastrostomy should be employed to make sure a catheter exchange was properly done. However, it is difficult to enforce an inspection using an X-ray or endoscopy in the home care environment. Here we examined the usefulness and problems associated with ultrasound catheter-validation for home care environment. Of 33 patients who received gastrostomy, we focused on 6 patients who had gastrostomy exchanged at home. Four out of 6 patients with a balloon-type gastrostomy exchanged clearly confirmed a good result by ultra sound. However, a patient with bumper-type was unclear. The reason being unclear was due to the material and shape of the appearance by the echo. Left costal arch operations approach is to scan the probe along the left side of the abdomen below the costal arch, so that a replaced gastrostomy catheter could be confirmed by following the low echoic area of the spleen, stomach vault and into the stomach cavity. It is considered that ultrasound examination of the exchanged balloon-type gastrostomy was useful under a consideration of patient's health conditions.     

Assessment of health-related quality of life after radiofrequency ablation or laparoscopic surgery for small renal cell carcinoma: a prospective study with medical outcomes Study 36-Item Health Survey (SF-36)

OBJECTIVE: The purpose of this study was to assess the changes in health-related quality of life (HRQoL) during follow-up period in patients treated with percutaneous radiofrequency ablation (RFA) or laparoscopic surgery for small renal cell carcinoma. METHODS: From December 2004 through September 2006, for 37 consecutive patients, who were diagnosed with renal cell carcinoma and underwent percutaneous RFA (n = 20) or laparoscopic radical nephrectomy (n = 17) at our institution. HRQoL was evaluated prospectively using SF-36 Health survey pre- and post-operatively (1, 4, 12 and 24 weeks after surgery). RESULTS: Four of the eight scale scores of SF-36 were significantly lower pre-operatively in the RFA group than in the laparoscopic surgery group. The QoL scores in physical functioning, role-physical functioning and role-emotional functioning were significantly reduced one week after laparoscopic surgery. However, there was no reduction of the SF-36 QoL scores one week after operation in the RFA group. Furthermore, HRQoL scores in the RFA group showed a tendency to improve during follow-up periods. CONCLUSIONS: This is the first study to evaluate HRQoL changes (up to 24 weeks) in patients who have undergone RFA or laparoscopic radical nephrectomy for small renal cell carcinoma. No reduction, but rather an improvement, in HRQoL was seen in the RFA group during follow-up periods. From the point of view of QoL, RFA could be a viable alternative treatment for selected patients with small renal cell carcinoma. RFA could be a viable alternative treatment for the selected patients with small renal cell carcinoma.