机械总院研发立式冷摆动辗压机填补国内空白

机械科学研究总院北京机电研究所承担“2000KN立式冷摆动辗压机开发研究”项目通过验收,研发的2000kN矿式冷摆动辗压机具有自主知识产权,填补了国内空白,达到国际先进水平,人选“2013度中关村科技园区首台（套）重大技术装备试验、示范项目。     

Prevalence and incidence of hand dermatitis in hairdressing apprentices: results of the POSH study. Prevention of occupational skin disease in hairdressers

OBJECTIVE: Occupational skin changes in hairdressers are very common. Morbidity, however, has not yet been quantified precisely. METHODS: A cohort of 2,352 hairdressing apprentices (of the 2,570 invited to participate, i.e., 91.5% response) was prospectively followed for the duration of their vocational training (3 years) by three examinations. Three waves (years) were recruited in 1992, 1993, and 1994 from 15 vocational training schools in northwestern Germany. RESULTS: The point prevalence of (mostly slight) irritant skin changes of the hands increased from 35.4% in the initial examination to 47.5% in the intermediate examination and to 55.1% in the final examination. Given a more conservative definition of a case of "hand dermatitis," these estimates were 12.9%, 23.5%, and 23.9%, respectively. Altogether, 34.3 and 15.2 cases of "skin changes (any degree)" and "hand dermatitis," respectively, in 100 person-years were observed during the study period. The incidence rate, i.e., the number of newly diseased study participants in relation to the person-time at risk contributed, decreased in the course of the study. The proportion of dropouts until final follow-up was 51.8%. CONCLUSION: The present results appear to lie in a range with those found in other, much smaller cohort studies. However, comparison of the results is hampered either by the lack of a clear definition or by a different definition of "person-time at risk" or "a case of hand dermatitis." As compared with an external control group of office apprentices, the incidence was several times higher in hairdressing apprentices, which points to the high risk for skin damage in this occupation.     

Double contrast examination of the stomach. Definition, technic and indications

Double contrast examination constitutes an important element in radiological gastric examination. The author examines the history of the term "double contrast" and defines the designation of "double contrast examination". The exclusive use of the double contrast method reduces the diagnostic value of gastric X-ray examinations. Thus a method is suggested that will avoid the disadvantages of exclusive double contrast examination while adequately including double contrast in the gastric examination. This is done by using various methods - according to the problem posed - in order to achieve the double contrast.     

Investigation of the loss of bone mineral in patients with spinal cord injury

1. Blood pressure, blood volume and renal blood flow were determined in 101 men; forty-three were normal subjects and fifty-eight were untreated permanent essential hypertensive patients with normal renal function and equilibrated sodium balance. 2. A significant negative pressure-volume relationship was observed overall. The relationship could be expressed as a hyperbola whose slope expressed the reduction in blood volume per unit rise in pressure: the higher the blood pressure, the lower the slope. Thus essential hypertensive subjects have a smaller decrement in blood volume per unit rise in pressure than normal subjects. 3. The relation between change in blood volume and change in pressure was confirmed in each individual by defining for each a ration deltaV/deltaP, statistically identical with the hyperbolic slope dV/dP. The deltaV/deltaP ratio was found to be well correlated with the renal blood flow and the creatinine clearance. No correlation existed between the total blood volume and these two renal parameters. 4. It is concluded that the present study demonstrates a blood volume regulation disturbance in essential hypertension and provides evidence from human studies that a renal defect accompanies high blood pressure.     

Interactions between arginine-rich histones and deoxyribonucleic acids. II. Circular dichroism

Circular dichroism (CD) was used to investigate the conformations of arginine-rich histones, H3 (III or f3) and H4 (IV or f2a1), and DNA in the complexes prepared by four different methods: (A) NaCl gradient dialysis with urea; (B) NaCl gradient dialysis without urea; (C) direct mixing in 2.5 x 10(-4) M EDTA, pH 8.0; and (D) direct mixing in 0.01 M sodium phosphate, pH 7.0. Using the CD spectrum of native chromatin as a criterion to judge the closeness of a complex to its native state, it was observed that a complex made by direct mixing at low ionic strength (methods C and D) is better than the ones made by NaCl gradient dialysis with or without urea (methods A and B). It is explained as a result of lack of ordered secondary structures in histones due to the presence of urea in method A or due to nonspecific aggregation in NaCl without urea (method B). Compared with all the earlier reports in literature on the CD of histone-DNA complexes, the CD spectra of arginine-rich histone-DNA complexes prepared by methods C and D are closest to that of native chromatin both in shape and in amplitude. These results imply (a) that arginine-rich histones play an important role in maintaining the conformation of chromatin and (b) that the binding of these two histones to DNA prepared by methods C and D are close to that in native chromatin. Noticeable variation in conformation of free and bound histone and histone-bound DNA has also been observed in histone H3 with one or two cysteine residues, and in reduced or oxidized state even when the complexes were prepared and examined in the same condition. CD spectra of arginine-rich histones in 0.01 M phosphates, pH 7.0, indicate the presence of alpha-helix which could be responsible for a favorable binding of the less basic regions of these histones to DNA under this condition as demonstrated by thermal denaturation (Yu, S. .S, Li H. J., and Shih, T. Y. (1976), Bio-chemistry, the preceding paper in this issue). To preserve or generate alpha-helical structures in histones seems to be a critical step in reconstituting good histone-DNA complexes.     

Malignant hyperthermia: attempt at an early diagnosis by means of determination of creatine phosphokinase (CPK) and its isoenzymes

Creatinphosphokinase (CPK) was elevated in sera of patients with malignant hyperthermia and in sera of some of their relatives. Only the MM-isoenzyme (but not the MB- or the BB-isoenzyme) could be detected by paperchromatographic analysis. In some of the patients elevation of muscle aldolase was also observed. Thus, the appearance of the BB-isoenzyme in sera of patients with malignant hyperthermia, as described by another group of investigators, was not confirmed. No specific screening method exists as yet to detect patients with a high risk of developing this often lethal reaction to anesthesia. However, in patients without muscle disease or trauma and without prior i.m. injections, myocardial infarction or major physical strain, elevation of CPK in serum should be interpreted as meaning that malignant hyperthermia may develop during anesthesia. The pathophysiology of malignant hyperthermia is discussed.     

The effect of high sugar intake on the esterification of dihydroxyacetone phosphate by rat liver microsomes

Rat liver microsomes were used as an enzyme source to study dietary-induced changes in the rate of dihydroxyacetone phosphate esterification. Rats were fed (1) 75% glucose or fructose diets for various time intervals, or (2) fed a fractose diet for six days and then a chow diet. Both the glucose and fructose diets produced a 2--3-fold increase in total and neutral glycerolipid formation from dihydroxyacetone phosphate measured in the presence of ATP, palmitate, CoA, and NADH. The increased rate of dihydroxyacetone phosphate esterification and a simultaneous rise in serum triglyceride level in rats fed fructose was rapidly reversed when chow was substituted for the fructose. The results indicate that an increased rate of dihyroxyacetone phosphate esterification may contribute to the acceleration of endogenous glycerolipid biosynthesis noted under these dietary conditions.