Vinyl polymerization. 120. Mutual copolymerization of p-substituted styrenes through radical mechanism

The radical mutual copolymerization of p-substituted styrenes, such as p-methoxy-, p-chloro-, p-bromo-, p-cyanostyrene, and styrene was carried out with one another at 30°C. in the dark. As initiator, azobisisobutyronitrile was used. The plots of the copolymerization rates against HAMMETT 's σ values showed no linear relationships and the concave curves were obtained therefrom. The relative reactivities of p-substituted styrenes with a definite p-substituted polystyryl radical, which were shown by the reciprocal of monomer reactivity ratio r₁, were plotted against σ values and concave curves were also obtained. The relative reactivities of p-substituted polystyryl radicals with p-substituted styrene were calculated from the ratios r₂ and the propagation rate constants in homopolymerization. the plots of them against σ values gave straight lines with different ρ values, according to the polarity of substituents. These results suggest that polar structures in transition state affected markedly the copolymerization rates. The effect of substituents on resonance stabilization was also quantitatively estimated.     

Lysosome is a primary organelle in B cell receptor-mediated apoptosis: an indispensable role of Syk in lysosomal function

To investigate the mechanism of B cell receptor (BCR)-mediated apoptosis, we utilized immature B cell lines, DT40 and WEHI-231. In both cell lines, BCR-crosslinking caused the increase in lysosomal pH with early apoptotic changes characterized by chromatin condensation and phosphatidylserine exposure. This increase was detected in c-Abl-deficient DT40 cells but not in Syk-deficient cells, which corresponded to the fact that the former cells but not the latter revealed BCR-induced apoptosis. In contrast, BCR-crosslinking caused no apparent change in mitochondrial transmembrane potential. Therefore, the lysosomal change might be a primary event in BCR-induced apoptosis in DT40 cells. The increased activity of cathepsin B and apoptosis-preventing effect of a cathepsin inhibitor suggested a significant role of lysosomal enzymes in this apoptosis. By microscopic studies, lysosomes of wild-type DT40 cells fused to BCR-carrying endosomes became enlarged and accumulated one another. In contrast, these changes of lysosomal dynamics did not occur in Syk-deficient cells but transfer of wild-type Syk restored the lysosomal changes and apoptosis. These results demonstrated that the lysosomal change accompanied with the activation of lysosomal enzymes is a primary step in BCR-crosslinking-mediated apoptosis and Syk is responsible for this step through the fusion of BCR-carrying endosomes to lysosomes.     

Determination of the depth of 50% of maximum ionization, I50, for electron beams by the divided difference method

A new characterization of depth-ionization parameters for electron beams is empirically deduced from our data analysis based on the divided difference method (the DD method), which employs the numerical differential of an ionization curve. The important feature of the present method is that it does not necessarily require normalized percent depth-ionization (NPDI) data. The depth of 50% of maximum ionization, I50, which is an important parameter for electron beam dosimetry, can be deduced from the analysis of an unnormalized (or partial) depth-ionization (UDI) curve obtained over a short interval of depth. The values of I50 determined by the DD method are in agreement to within 0.1 mm for energies of 4, 6, and 9 MeV, compared with the ones determined by the TG-51 protocol method (or the conventional method), and the difference was 0.9 mm for 12 and 15 MeV. The dose at the reference depth, dref, calculated from I50 by the DD method, is found to be in agreement with TG-51 to within 0.1%. The field size dependence of the DD method using UDI data was studied for three field sizes: 6 x 6, 10 x 10, and 20 x 20 cm2. For all energies, the discrepancies of I50 as determined by both methods were 0.9 mm on average for the 6 x 6 cm2 fields and 0.6 mm for the other two field sizes. This dependence was remarkable for 6 x 6 cm2 fields for 12 and 15 MeV, and the discrepancies shown by the DD method were 1.2 mm for 12 MeV and 1.8 mm for 15 MeV, respectively. Since the reference field size in clinical dosimetry is usually 10 x 10 cm2, this dependence will not affect clinical dosimetry. The DD method could be an alternative option for checking beam quality in dose calibration.     

Lessons learned from lower urinary tract complications of anorectoplasty for imperforate anus with rectourethral/rectovesical fistula: Laparoscopy-assisted versus posterior sagittal approaches

PurposeTo report the sequelae of and preventive strategies for selected lower urinary tract (LUT) complications, i.e., posterior urethral diverticulum (PUD), intraoperative LUT injuries, postoperative dysuria, and fistula recurrence in male imperforate anus (IA) with rectourethral/rectovesical (RU/RV) fistula after laparoscopy-assisted anorectoplasty (LAARP) or posterior sagittal anorectoplasty (PSARP).Methods153 boys with IA and RU/RV fistula treated 1986–2019 by LAARP (n = 56) or PSARP (n = 97) at two unrelated institutes were studied retrospectively.ResultsAfter mean follow-up of 17.0 years (range: 36.5 days-32.0 years), the overall incidences of LUT complications were: LAARP (6/56; 10.7%); PSARP (7/97; 7.2%); p = 0.55, comprising PUD: LAARP (n = 5), PSARP (n = 0); p = 0.006; injuries: LAARP (n = 0), PSARP (n = 5); p = 0.16; dysuria: LAARP (n = 1), PSARP (n = 1); p>0.999; and recurrence: LAARP (n = 0), PSARP (n = 1); p>0.999. Mean onset of PUD was 5.1 years (range: 1.0–15.1 years). Treatment: PUD: surgery (n = 2/5), conservative (n = 3/5); injuries: intraoperative repair (n = 5/5); dysuria: conservative (n = 2/2), and recurrence: redo PSARP (n = 1/1).ConclusionsStrategies devised to improve dissection accuracy resolved the specific technical issues causing LUT complications (remnant RU fistula dissection in LAARP and blind posterior access in PSARP). Currently, the incidence of new cases of PUD and LUT injuries is zero.Level of Evidence: Level III     

Nomograms predicting extra- and early intrahepatic recurrence after hepatic resection of hepatocellular carcinoma

BackgroundExtrahepatic recurrence and early intrahepatic recurrence of hepatocellular carcinoma after hepatic resection are indicative of poor prognoses. We aimed to develop nomograms to predict extrahepatic recurrence and early intrahepatic recurrence after hepatic resection.MethodsThe participants of this study were 1,206 patients who underwent initial and curative hepatic resection for hepatocellular carcinoma. Multivariate logistic regression analyses using the Akaike information criterion were used to construct nomograms to predict extrahepatic recurrence and early intrahepatic recurrence (within 1 year of surgery) at the first recurrence sites after hepatic resection. Performance of each nomogram was evaluated by calibration plots with bootstrapping.ResultsExtrahepatic recurrence was identified in 95 patients (7.9%) and early intrahepatic recurrence in 296 patients (24.5%). Three predictive factors, α-fetoprotein >200 ng/mL, tumor size (3–5 cm or >5 cm vs ≤3 cm), and image-diagnosed venous invasion by computed tomography, were adopted in the final model of the extrahepatic recurrence nomogram with a concordance index of 0.75. Tumor size and 2 additional predictors (ie, multiple tumors and image-diagnosed portal invasion) were adopted in the final model of the early intrahepatic recurrence nomogram with a concordance index of 0.67. The calibration plots showed good agreement between the nomogram predictions of extrahepatic recurrence and early intrahepatic recurrence and the actual observations of extrahepatic recurrence and early intrahepatic recurrence, respectively.ConclusionWe have developed reliable nomograms to predict extrahepatic recurrence and early intrahepatic recurrence of hepatocellular carcinoma after hepatic resection. These are useful for the diagnostic prediction of extrahepatic recurrence and early intrahepatic recurrence and could guide the surgeon’s selection of treatment strategies for hepatocellular carcinoma patients.     

A digest of the Evidence-Based Clinical Practice Guideline for Nephrotic Syndrome 2020

Clinical and Experimental Nephrology -     

Prevention of postischemic reperfusion injury: The improvement of myocardial tissue blood flow after ischemia by terminal Nicorandil-Mg cardioplegia

We evaluated the preventive effect of postischemic reperfusion injury by Nicorandil-Mg cardioplegia given just prior to reperfusion as terminal cardioplegia. Twenty seven dogs were placed on cardiopulmonary bypass and the aorta was cross-clamped for 90 min under hypothermic (17–19°C) cardioplegic arrest. The canine hearts were divided into three groups: in group A (n=10) the hearts were reperfused without any treatment; in group B (n=9) the hearts received coronary perfusion with Nicorandil-Mg solution (Nic, 8 mg/l; Mg, 20 mEq/l; glucose, 50 g/l) for 2 min just prior to reperfusion; and in group C (n=8) the hearts received coronary perfusion with Nicorandil-Mg free solution (glucose, 50g/l). During and after ischemia, the myocardial tissue PCO₂ (t-PCO₂) was continuously monitored by an ion-sensitive field effective transistor (ISFET) sensor. In addition, the myocardial tissue blood flow (TBF), oxygen consumption, and lactate flux were then calculated at 5, 10, 20, and 40 min of reperfusion. In the initial reperfusion period, Group B showed an improved TBF compared to group A and C (at 5 min, group B was 42.7±11.9; group A was 29.4±11.2, P<0.025; and group C was 33.9±9.2% of the preischemic control level, P<0.05). T-PCO₂ in group B was significantly decreased at 5 min of reperfusion (group B, 127.5±22.5 42.5±9.7; group A, 117.5±23.0 85.2±17.4, P<0.001; group C, 122.3 mmHg 68.2±18.7 mmHg, P<0.01), and group B had a better metabolic recovery. These results suggest that terminal Nicorandil-Mg cardioplegia might reduce the rate of postischemic reperfusion injury.     

Risk factors for hepatocellular carcinoma at baseline and 1 year after initiation of nucleos(t)ide analog therapy for chronic hepatitis B

Nucleos(t)ide analogs (NAs) cannot completely suppress the risk of hepatocellular carcinoma (HCC) in patients with chronic hepatitis B (CHB). This study aimed to identify the risk factors for HCC development in naïve CHB patients treated with current NA. Patients receiving NA (n = 905) were recruited retrospectively from the 17 hospitals of the Japanese Red Cross Liver Study Group. All treatment-naïve patients had been receiving current NA continuously for more than 1 year until the end of the follow-up. We analyzed the accuracy of predictive risk score using the area under receiver operating characteristic curve. The albumin–bilirubin (ALBI) score was significantly improved by NA therapy (−0.171 ± 0.396; p < 0.001 at Week 48). A total of 72 (8.0%) patients developed HCC over a median follow-up of 6.2 (1.03–15.7) years. An independent predictive factor of HCC development was older age, cirrhosis, lower platelet counts at baseline and ALBI score, and alpha-fetoprotein (AFP) at 1 year after NA therapy according to multivariate analysis. The accuracy was assessed using the PAGE-B, mPAGE-B, aMAP, APA-B, and REAL-B scores that included these factors. Discrimination was generally acceptable for these models. aMAP and REAL-B demonstrated high discrimination with 0.866/0.862 and 0.833/0.859 for 3- and 5-year prediction from the status of 1 year after NA therapy, respectively. Baseline age and platelet count, as well as ALBI and AFP one year after NA, were useful for stratifying carcinogenesis risk. The aMAP and REAL-B scores were validated with high accuracy in Japanese CHB patients.