紫外辐射低温消化反应器在测定羊水微量元素(锌、铜)中的应用

测定妊娠期妇女羊水中微量元素锌、铜(Zn、Cu)的含量变化,对预测胎儿的发育情况,具有一定的参考价值。本文介绍一种利用紫外辐射消化技术,对羊水进行预处理后,再用阳极溶出伏安(ASV)方法测定。讨论了辐射条件,并通过重复性、回收率及线性关系来证实方法的可靠性和准确性。与传统的湿式消化法相比,紫外辐射法有取样量少、温度低)、不易挥发、操作简便及较低的试剂空白值等优点。     

The hospital as an enterprise: management strategies

After introducing the context in which health systems exist in developing as well as in industrialized countries, the author describes the role that hospitals are expected to play as 'enterprises'. The rationale behind such a role is explored and the experience so far available discussed. Evidence from several developing countries suggests caution and tends to discourage radical and indiscriminate introduction of market‐oriented reforms, which international donors seem to be spearheading in Africa's health systems. It is likely, however, that a limited, gradual introduction of selected elements of these reforms (such as some aspects of contracting out, managerial decentralization, the split between purchasing and providing functions) may find its place and eventually have a positive impact on the performance of the health systems. But the 'mystique of markets' must not be allowed to deprive public hospitals of the sense of social utility and of the caring ethos which are essential requisites of a meaningful and effective public health system.     

Differential titin isoform expression in human skeletal muscle

Mammalian skeletal muscle expresses at least two isoforms of the cytoskeletal protein titin (connectin; MW ≈ 3000 kDa). These isoforms are associated with different passive force curves, and thus may affect physical performance. To study the distribution of titin and its possible influence on performance in humans, muscle biopsies were obtained from 15 males (X ± SE; age = 25.4 ± 2.9 years, height = 177.7 ± 1.8 cm, weight = 76.5 ± 2.2 kg). Two biopsies were obtained on separate occasions from both the right and left vastus lateralis, and one biopsy each from the lateral head of the right gastrocnemius and the right soleus, with all biopsies handled identically. Fibre type analyses were performed via mATPase histochemistry. Expression of titin and myosin heavy chain isoforms were determined by SDS-PAGE. Titin bands in the resulting gels were highly repeatable and were verified by migration patterns, as well as Western blot analysis. Two groups of subjects were identified: group 1 (n=10) expressed only one titin isoform (titin-1) in all biopsies, and group 2 (n=5) expressed two titin isoforms (titin-1 and titin-2) in all biopsies. No significant differences (P> 0.05) between groups were observed for percentage fibre types, percentage fibre type areas, fibre type cross-sectional areas, and percentage myosin heavy chain expression when comparing individual muscles, sampling times or bilateral comparisons. This is the first report of differential titin isoform expression in healthy, mature human skeletal muscle, but it is not clear why this occurs or what influence this may have on performance.     

Local thermal sensation and finger vasoconstriction in the locally heated hand

Summary The effects of local heating on finger blood flow (BF) and local thermal sensation (Sens _w ) were studied. Finger BFs in both hands were measured simultaneously; one hand was immersed in water the temperature (T _w ) of which was raised from 35° C to 43°C by steps of 2° C every 10 min, while the other hand was kept atT _w 35°C. FingerBF in the locally heated hand decreased atT _w 37 to 41°C, while fingerBF in the control hand did not alter. Sens_w, in the heated hand showed a dynamic response, initially increasing concomitantly with an increase inT _w , then gradually returning and adapting to a new level of Sens_w. The dynamic response of Sens_w, was not perceived during mental calculation even whenT _w was raised to 40°C, and the reduction in finger blood flow was not observed. These results suggest that finger vasoconstriction caused by local heating closely relates to the dynamic response characteristic of local thermal sensation atT _w above core temperature, and that the perception of local thermal sensation in the central nervous system is involved in the mechanism of this vasoconstrictor response.     

Induction of specific anti-actin antibodies and their measurement by ELISA technique.

Using the ELISA technique we have been able to quantify antibodies directed against actin and to follow the kinetics of antibody production. Specific anti-actin antisera have been raised in rabbits by immunization with chemically modified white muscle rabbit actin. Two or three dinitrophenyl groups linked per actin molecule were sufficient to break natural tolerance, while linkage of three phosphorylcholine groups to actin was not.     

Favourable associations between the myosin heavy-chain and light-chain isoforms in human skeletal muscle

Histochemical and biochemical analyses were performed in order to examine the relationship between myosin light-chain (LC) isoforms and fibre-type distributions in whole human skeletal muscle. Muscle biopsies were obtained from the vastus lateralis muscle in six healthy men, and analysed for the relative area occupied by each fibre type (percentage of fibre type area) and the molar ratio of each LC isoform. The percentage of type I fibre area was positively correlated with the molar ratio of slow LC (LC1s and LC2s) to total LC. The regression line was located below the line of unity. Also, the ratio of percentage of type II fibre area to that of type II fibre area was positively correlated with the molar ratio of the fast alkali LC LC1f to fast alkali LCs LC1f and LC3f. These results support previous study, having shown that in human skeletal muscle some type I fibres express various amounts of fast LC in addition to slow LC and suggest that fast myosin heavy-chain HCII a is favourably associated with LC1f, whereas HCIIb is favourably associated with LC3f.     

Allergic conversion of protective mucosal immunity against nasal bacteria in patients with chronic rhinosinusitis with nasal polyposis

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Heavy-ion-induced mutations in the gpt delta transgenic mouse: comparison of mutation spectra induced by heavy-ion,X-ray,and gamma-ray radiation

Heavy-ion radiation accounts for the major component of absorbed cosmic radiation and is thus regarded as a significant risk during long-term manned space missions. To evaluate the genetic damage induced by heavy particle radiation, gpt delta transgenic mice were exposed to carbon particle irradiation and the induced mutations were compared with those induced by reference radiations, i.e., X-rays and gamma-rays. In the transgenic mouse model, deletions and point mutations were individually identified as Spi(-) and gpt mutations, respectively. Two days after 10 Gy of whole-body irradiation, the mutant frequencies (MFs) of Spi(-) and gpt were determined. Carbon particle irradiation significantly increased Spi(-) MF in the liver, spleen, and kidney but not in the testis, suggesting an organ-specific induction of mutations by heavy-ion irradiation. In the liver, the potency of inducing Spi(-) mutation was highest for carbon particles (3.3-fold increase) followed by X-rays (2.1-fold increase) and gamma-rays (1.3-fold increase), while the potency of inducing gpt mutations was highest for gamma-rays (3.3-fold increase) followed by X-rays (2.1-fold increase) and carbon particles (1.6-fold increase). DNA sequence analysis revealed that carbon particles induced deletions that were mainly more than 1,000 base pairs in size, whereas gamma-rays induced deletions of less than 100 base pairs and base substitutions. X-rays induced various-sized deletions and base substitutions. These results suggest that heavy-ion beam irradiation is effective at inducing deletions via DNA double-strand breaks but less effective than X-ray and gamma-ray irradiation at producing oxidative DNA damage by free radicals.     

Ca2+ and Sr2+ activation: Comparison of cardiac and skeletal muscle contraction models

The mechanism of contraction in rabbit fast-twitch, and bovine and rabbit cardiac muscle was examined using functionally skinned fibers, ATPase activity of myofibrils, and cardiac or skeletal troponintropomyosin regulated actin heavy meromyosin. The Ca²⁺ and Sr²⁺ activation properties for the different measures of contraction were evaluated. (1) Tension in rabbit and bovine cardiac skinned fibers and rabbit cardiac myofibrillar ATPase were activated equally well by either Ca²⁺ or Sr²⁺. By contrast, rabbit adductor magnus (fast-twitch) skinned fibers required substantially higher [Sr²⁺] than [Ca²⁺] for activation, as did rabbit myofibrils from back muscle (fast-twitch). (2) Substantially more Sr²⁺ than Ca²⁺ was also required for activation of skeletal muscle actin heavy meromyosin ATPase, controlled by either the skeletal or cardiac troponin-tropomyosin complex, similar to the activation of fast-twitch muscle. (3) The absence of correlation between the divalent cation selectivity properties of actin heavy meromyosin ATPase controlled by cardiac troponin-tropomyosin and cardiac muscle tension or myofibrillar ATPase activation by Ca²⁺ and Sr²⁺ suggests that troponin, if primarily responsible for the activation of cardiac muscle, has very different in vivo and in vitro binding properties. (4) The close correlation between percentage of maximal Ca²⁺- and Sr²⁺-activated myofibrillar ATPase and tension in skinned fibers strongly justifies the use of myofibrillar ATPase, in contrast to a reconstituted troponin-tropomyosin actin heavy meromyosin ATPase system, as a biochemical measure of contraction.     

Correlation between percentage fiber type area and myosin heavy chain content in human skeletal muscle

Histochemical methods are routinely used to delineate skeletal muscle fiber types. In the present investigation, this qualitative determination of fiber type composition was compared to the electrophoretically determined myosin heavy chain (MHC) content from a large number of human muscle biopsy samples. Biopsies were taken from the vastus lateralis muscle at the beginning and every 2 weeks during 8 weeks of highi-ntensity resistance training from men (n = 13) and woman (n = 8). Muscle was also extracted from nontraining men (n = 7) and women (n = 5) at the same periods. Six muscle fiber types (I, IC, IIAC, IIA, IIAB, and IIB) were determined using basic myofibrillar adenosine triphosphatase histochemistry. Cross-sectional areas were determined for the three major fiber types (I, IIA, and IIB) and used to calculate the percentage area of these types. Electrophoretic techniques were used to separate and quantify the percentage MHC content in these same biopsy samples, and these data were then used to compare with the percentage fiber type area. Correlation analyses suggest a relationship between the histochemically assessed percentage fiber type area and the electrophoretically assessed MHC content in human limb musculature. However, because of possible histochemical misclassification of some fibers (especially in trained muscle) both techniques may be essential in yielding important information about fiber type composition and possible fiber type transformations.