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.     

Differences in the abilities of individual fingers during the performance of fast,repetitive tapping movements

Using 12 healthy male subjects, the dynamic motor ability of individual fingers was investigated under four different finger tapping conditions. These were: maximum speed tapping with one finger (single-finger tapping), alternate movement of two fingers (double-finger tapping), double-finger tapping in an unsupported condition, and submaximum constant speed tapping with one finger in a passive manner. Key-contact forces for all fingers and the movement velocity of the tapping finger were monitored. With the exception of the unsupported condition, non-tapping fingers were maintained in contact with designated keys during the tapping tasks. It was found that the index finger attained the fastest cadence and greatest movement velocity, followed by the middle, little and ring fingers, respectively. Subjective assessment of rank order of "difficulty" of tapping by the subjects was highly correlated with tapping cadence. Thus dynamic motor function, as indicated by rapid, repetitive movement, differs among the individual fingers. Parallel changes were observed in the key-contact force of the neighboring non-tapping fingers during tapping. The range of the non-tapping finger forces was largest during tapping by the ring finger. A similar trend was found for passive tapping, during which the magnitude of key-contact force was less than one-third of that observed during active tapping. The lower cadence achieved by the ring finger may be attributed more to a lack of independence at the level of voluntary neuromuscular control, than to innate mechanical interaction with the other fingers. Tapping cadence of each finger was lower for the double-finger mode than for the single-finger mode. The magnitude of the observed decrease in cadence during double-finger tapping was, on the other hand, strongly dependent on finger-combination. The decrease was smallest for the index-middle finger-combination, and greatest for the ring-little finger-combination. Compatibilities with other fingers can play an essential role in the dynamic motor function of individual fingers. During the unsupported task, in which interactions were diminished by allowing all fingers to move freely, tapping cadence increased markedly. Therefore, the lower cadences observed in specific finger-combinations may be partly attributed to anatomical and neural interdigit interactions.     

Proliferation,apoptosis, and intratumoral vascularity in multiple myeloma: correlation with the clinical stage and cytological grade

AIMS: Abnormalities involving proliferation, apoptosis, and angiogenesis are important in tumorigenesis. The purpose of this study was to examine these three biological processes, and their relation with the clinical stage and cytological grade in multiple myeloma (MM). METHODS: Fifty four newly diagnosed patients with MM were studied by immunohistochemistry using bone marrow clot sections. Proliferation and apoptosis were evaluated for the proportion of MM cells (indicated by morphology and CD138 reactivity) positive for the Ki67 antigen and single stranded DNA (ssDNA), respectively. Angiogenesis was evaluated by measuring the intratumoral microvessel density (IMVD) and by assessing the immunoreactivity of vascular endothelial growth factor (VEGF). RESULTS: There were 30 men and 24 women (median age, 65 years; range, 37-84). At initial presentation, 15 (28%) were in Durie stage I, 15 (28%) in stage II, and 24 (44%) in stage III. Advanced clinical stage correlated with high cytological grade (p < 0.03). The medians for Ki67, ssDNA, and IMVD were 4.4% (range, 0-15%), 0.2% (range, 0-2.8%), and 15.5 (range, 0-63), respectively. Among these three continuous parameters, the only significant correlation was that between Ki67 and IMVD (p < 0.0001). Both Ki67 and IMVD also correlated with the clinical stage, cytological grade, and VEGF positivity (p <0.05). No correlation was found between ssDNA and all of the other parameters. CONCLUSIONS: These data suggest that proliferation is associated with angiogenesis in MM. Furthermore, proliferation and angiogenesis, but not apoptosis, may be important in disease progression. Lastly, increased production of VEGF may be one of the contributing factors to the increase in intratumoral vascularity seen in advanced MM.     

Active and inactive renin after exercise

Summary The effects of graded exercise on plasma concentrations of active and inactive renin were studied in seven healthy men. Exercise was performed on a cycle ergometer at four different exercise intensities (corresponding to 30%, 50%, 80% and 87% of ) for 10 min each. Concentrations of active renin and total renin after activation by trypsin were measured by direct immunoradiometric assay. Non-trypsin-activated renin concentration (inactive) was obtained by subtraction. Active renin concentrations at 30%, 50%, 80% and 87% of were 1.2, 1.9, 3.1 and 4.6 times higher than the control concentration, respectively. Similar increases in plasma renin concentration, determined by conventional enzymatic assay, were observed at every stage. In contrast, changes in inactive renin concentration were not significant at any stage. Significant increases in noradrenaline concentration were found at every exercise stage, but adrenaline, aldosterone and lactate concentrations were significantly elevated only after exercise at 50%, 80% and 87% of . The similarity between the changes in concentration of active renin and noradrenaline would suggest that sympathetic nerve activity may have been responsible either for the release of active renin or for the conversion of inactive renin to its active form in the kidney.     

Hyperplastic foci in chronic liver disease: Their proliferative activity assessed by nucleolar organizing region

In the cirrhotic and precirrhotic liver, there may be small foci with increased cellularity and amphophilic cytoplasm. These are microscopic lesions that do not form macroscopically detectable nodules, which differ from the macroscopically apparent nodules of dysplastic nodules. In the present study, we assessed the proliferating activity of 12 hyperplastic foci in 11 patients with cirrhosis or chronic hepatitis, by staining for agyrophilic nucleolar organizing regions (AgNOR). The mean AgNOR count per nucleus in the hyperplastic foci ranged from 0.96 to 1.36 (mean, 1.13; SD 0.12), and from 0.81 to 1.06 (mean, 0.94; SD 0.08) in the controls. The AgNOR count In the hyperplastic foci was significantly higher than that In the controls (P> 30.01). Small hyperplastic foci show Increased proliferative activity. Further study on these foci is required to clarify their relation to hepatocarcinogenesis.     

No evidence of PEG1/MEST gene mutations in Silver‐Russell syndrome patients

Silver‐Russell syndrome (SRS) is characterized by prenatal and postnatal growth retardation with morphologic anomalies. Maternal uniparental disomy 7 has been reported in some SRS patients. PEG1/MEST is an imprinted gene on chromosome 7q32 that is expressed only from the paternal allele and is a candidate gene for SRS. To clarify its biological function and role in SRS, we screened PEG1/MEST abnormalities in 15 SRS patients from various standpoints. In the lymphocytes of SRS patients, no aberrant expression patterns of two splice variants (α and β) of PEG1/MEST were detected when they were compared with normal samples. Direct sequence analysis failed to detect any mutations in the PEG1/MEST α coding region, and there were no significant mutations in the 5′‐flanking upstream region containing the predicted promoter and the highly conserved human/mouse genomic region. Differential methylation patterns of the CpG island for PEG1/MEST α were normally maintained and resulted in the same pattern as in the normal control, suggesting that there was no loss of imprinting. These findings suggest that PEG1/MEST can be excluded as a major determinant of SRS. © 2001 Wiley‐Liss, Inc.     

Suitable image parameters and analytical method for quantitatively measuring cerebral blood flow volume with phase-contrast magnetic resonance imaging

The aim of this study was to determine suitable image parameters and an analytical method for phase-contrast magnetic resonance imaging (PC-MRI) as a means of measuring cerebral blood flow volume. This was done by constructing an experimental model and applying the results to a clinical application. The experimental model was constructed from the aorta of a bull and circulating isotonic saline. The image parameters of PC-MRI (repetition time, flip angle, matrix, velocity rate encoding, and the use of square pixels) were studied with percent flow volume (the ratio of actual flow volume to measured flow volume). The most suitable image parameters for accurate blood flow measurement were as follows: repetition time, 50 msec; flip angle, 20 degrees; and a 512 x 256 matrix without square pixels. Furthermore, velocity rate encoding should be set ranging from the maximum flow velocity in the vessel to five times this value. The correction in measuring blood flow was done with the intensity of the region of interest established in the background. With these parameters for PC-MRI, percent flow volume was greater than 90%. Using the image parameters for PC-MRI and the analytical method described above, we evaluated cerebral blood flow volume in 12 patients with occlusive disease of the major cervical arteries. The results were compared with conventional xenon computed tomography. The values found with both methods showed good correlation. Thus, we concluded that PC-MRI was a noninvasive method for evaluating cerebral blood flow in patients with occlusive disease of the major cervical arteries.     

A comparison of prehension force control in young and elderly individuals

Age-related changes were investigated in the control of precision grip force during the lifting and holding of objects with slippery (silk) and nonslippery (sandpaper) surface textures. Two groups of active elderly adults comprising individuals aged 69–79 years (n = 10), and 80–93 years (n = 10) together with a group of young adults aged 18–32 years (n = 10) participated in the study. Each subject lifted a free weight (3N) during which time gripping and lifting forces were monitored. The elderly subjects, especially the individuals in the 81–93 year group, had a larger number of fluctuations in the grip force rate curve and longer force application time than the younger subjects during lifting. The effect of prior experience with one surface on the following different surface was more pronounced in the younger subjects than the elderly subjects. These results suggest a decline in programmed force production capacity with increased age. The fingers of the elderly subjects were more slippery and they exhibited a greater safety margin of the grip force while holding the object than the younger adults. The overall results demonstrated that precision grip force control capacity declines with advancing age. It is suggested that this decline is due mainly to age-related changes in skin properties, and cutaneous sensibility functions, and in part to central nervous system function.