The relationship between cell size, the activity of DNA polymerase α and proliferative activity in human diploid fibroblast-like cell cultures

In kinetic studies with human diploid fibroblast-like (HDFL) cells carried out in heterokaryons and in monokaryons, we have observed a first-order relationship between the level or concentration of DNA polymerase α and the rate of initiation of new rounds of DNA synthesis. Because cell size is inversely proportional to the concentration of DNA polymerase α and presumably other replication factors, it is inversely related to the initiation of new rounds of DNA synthesis. An inverse relationship between cell size and clonogenic activity was also observed in both unsorted HDFL cells and in HDFL cells sorted on the basis of size. Experimental enlargement of cells by serum deprivation at low density resulted in changes in colony-forming ability that would be predicted by these studies. A causal relationship between the observed increase in cell size with advancing passage level and the loss of proliferative activity is suggested by these studies; in addition, cell size may be a useful biophysical marker for cellular aging.     

多原子体系的计算(Ⅰ)

对具2n个电子的多原子体系,其一阶约化密度矩阵可用n个基求解HFR方程的方式构出。ρ_1也可以把这n个基正交归一化后构出。对一些小分子,如FH,CH_4等从n个修正价键基出发得到了近似程度较高的ρ_1。     

Evidence that platelet buoyant density,but not size,correlates with platelet age in man

Following infusion of ⁵¹Cr-labeled autologous platelets into normal subjects, high-density (HD) and low-density (LD) platelet cohorts were isolated by prolonged centrifugation in isosmotic arabino-galactan (Stractan). Specific radioactivity of LD platelets declined rapidly post-infusion (T_1/2 = 1.5 days), but specific radioactivity of HD platelets remained constant or increased over a 3–4-day period and gradually declined for 6–7 days thereafter. These differences were exaggerated when platelet cohorts enriched in LD or HD cells by slow centrifugation in high-density albumin were labeled and transfused. Mean survival of a platelet cohort enriched with HD cells was significantly (P < 0.02) shorter (7.73 days) than that of a cohort enriched with LD cells (9.33 days). In normal subjects treated with aspirin, capacity for thromboxane synthesis was regained more rapidly (P < 0.05) in LD than in HD platelets. HD and LD platelets differed only slightly in mean volume (HD platelets = 7.57 μ³, LD platelets = 6.87 μ³, 0.05 < P < 0.01). We believe the most logical interpretation of these findings is that under normal conditions in man, newly formed platelets are less dense on the average than total platelets and become more dense as they age in the circulation. Thus, specific radioactivity of LD platelets declines rapidly as these platelets move into a more dense compartment and are replaced by newly formed, un-labelled cells; specific radioactivity of HD platelets remains constant or increases as labelled platelets enter this compartment in numbers equal to or greater than the number leaving it at the end of their life span. The similarity in mean volumes of LD and HD platelets suggests that platelet size is unrelated to platelet age under normal conditions.     

Atrioventricular conduction time - a heritable trait?

Routine electrocardiographic tracings (ECGs) were obtained from 491 male and 236 female Norwegians. The atrioventricular conduction time (P-R interval) was read independently on coded ECGs by two physicians. The frequency distributions are presented: mean ± 2 SD was 0.16 ± 0.04 s and 0.15 ± 0.04 s for males and females, respectively. Intra-individual repeatability over 1 year was high, and the measurement error was small. Within each sex, body size, age, heart rate and non-cardiac disease manifestations had little influence on the P-R interval. The P-R interval may be reliably determined in routine ECG tracinge by trained observers.     

蜂蜡骨架颗粒的粒度及含蜡量对生物利用度的影响

继承和发扬祖国药剂学的成就,蜂蜡骨架颗粒可以作为口服长效剂型的一种形式,释药缓慢且均衡。颗粒的粒度及含蜡量这两种因素,独立地对生物利用度产生影响,而含蜡量起主要作用。蜂蜡来源方便,特别是食用无害而较国外近年来用作骨架材料的合成高分子物质优越。颗粒的生物利用度较原蜡丸提高很多,对一般的非剧毒药也具有实用意义。     

Are right-hemisphere lesions really larger? Lesion size and laterality in meningioma patients

ABSTRACT— Patients with pathologically confirmed diagnoses of meningioma were examined to investigate the hypothesis that left-hemisphere lesions are smaller or declared earlier than right-hemisphere lesions. 77 patients were examined with regard to age at presentation and nature of symptoms. In addition CAT scan films of 47 patients were obtained for measurement of lesion size. There were no differences between right and left lesion groups with regard to size of lesion or age at presentation. Subgroups of patients with lesions in frontal association areas also did not differ. Some relationships were discovered between lesion location and nature of symptoms.     

Influence of surgical techniques on receptor levels and 5α-reductase activity of the human prostate gland

This study examines the effects of removing prostate specimens by different surgical techniques on the androgen receptor levels and 5α-reductase activity of the tissue. Comparison of specimen obtained by transurethral resection (TUR) with those from an open operation revealed that the size of the resected chips was critical in maintaining the hormonal activities of the specimens. Provided that the size (length x thickness) of the resected chips was greater than 1.5 × 0.4 cm there was no effect on either the androgen receptor levels or the testosterone-metabolizing activity of the tissue, and TUR specimens can therefore be reliably used to assess the hormonal activity of the gland.     

Studies on Lymphocytes XIII

A rapid method for measuring volume distributions of human, calf and goat lymphocytes and their nuclei is described along with the type of quantitation these measurements can provide by computer analysis. The size distribution studies indicate the presence of two populations of lymphocytes and their nuclei irrespective of the cell source. It is suggested that proliferative fractions of various cell populations may be estimated by determining the nuclear volume distribution.     

Platelet size distribution in mice following immunothrombopenia and vincristine administration

Summary In the present study platelet size distribution was investigated after induction of immunothrombocytopenia by rabbit-anti-mouse-platelet-serum (RAMPS) and after vincristine-induced thrombocytopenia.The platelet size distribution after a single dose of RAMPS showed a shift to larger volumes at day 1 and 2, and a decrease to slightly smaller volumes than normal at day 8. These differences, however, were not statistically significant.After vincristine administration, a dose-dependent increase of the platelet size distribution was demonstrated, which lasted from day 1–7.It is suggested that in immune-induced thrombocytopenia the young platelets released from bone marrow megakaryocytes are not exclusively large platelets. On the other hand the early appearance of large platelets after vincristine administration points to a toxic or segregating effect of vincristine on circulating platelets. Therefore, in our experiments, the platelet size is not suitable for the differentiation of young and old platelets.This study was supported by the Deutsche Forschungsgemeinschaft. Qu 33/1     

The prognostic significance of different histomorphologic features in chondrosarcoma

Summary Cellularity, mitotic rate and nuclear size were determined objectively in 47 chondrosarcomas. Grading was also performed, according to the systems of O'Neal and Ackerman and of Evans. The survival rate and incidence of metastases 10 years after diagnosis were calculated.The prognostic significance of the objectively determined cytological parameters was investigated. The accuracy of determination of these cytological parameters by grading (Evans) was also analyzed.Nuclear size seemed to be the best prognostic parameter, while cellularity appeared to be the strongest determinant for grading.Gross differences of nuclear size can be assessed visually, while more subtle, although prognostically significant, differences can only be determined by objective means.The results of this study indicate that the mere determination of nuclear size by objective means may give significant prognostic information, which is equal to, or even better than, conventional grading of chondrosarcoma.