The biological half-time of heavy metals

Summary Concentrations of Cd (475 samples), Pb (271), and total Hg (166) were determined in the organs and tissues during autopsies of inhabitants of the Tokyo metropolitan area who had experienced no known exposure to an abnormally high level of heavy metals and had died sudden deaths by accident. The results of this study do not differ greatly from those of other reports. Based on the intraorganic accumulation of the heavy metals according to age when they were not experimentally administered, the biological half-time (BHT) was estimated using a mathematical model with differential equations. It was hypothesized that the input of heavy metals into organs is proportional to the amount of food intake according to age (assuming little or no chronological change of heavy metals concentrations in food over several decades), and that the output is proportional to the intraorganic accumulation. The resulting BHT was very long, 10 to 100 times that computed in a number of studies from observation of the attenuation curve for a relatively short period after the experimental adminstration of heavy metals to humans or animals.The author devised a model consisting of two series compartments in one organ: the superficial, where heavy metals enter directly and are weakly bound with protein, and the profound, where they enter only via the superficial compartment to be strongly bound with the constituents. It was elucidated theoretically that the short BHT obtained by heavy metal administration is associated only with the superficial compartment of the organ, and that the long BHT obtained without experimental administration of heavy metals is due to the detour circuit from the superficial to the profound compartments. The ratio of the short BHT to the long BHT is the proportion of the content of a heavy metal in the superficial compartment to the total content in the whole organ. In order to prove the existence of the two compartments, superficial and profound, and to compute their ratios, further studies should be performed. The attenuation curve of the concentration, or of the amount after a single administration of a heavy metal, consists of the rapid component (first) and the slow component (second). The latter has been generally used for computation of BHTs. The slowest component is frequently present several years after the first two. There is a fair chance that the BHT based on the slowest component agrees with the BHT found in the present study.     

Growth patterns of blood cells in culture in the presence of polyethylene oxide 400 cryprotector

The effect of the cryoprotector polyethylene oxide 400 (PEO-400) on mitotic activity of human peripheral blood leukocytes was studied in cultures stimulated by phytohemagglutinin. The cytological features of growth of the blood cells when PEO)400 was added before the beginning of culture were expressed as continued ability of the cells to undergo transformation and mitotic division despite a sigificant decrease in the mitotic activity of the experimental cultures compared with the controls.Institute of Problems in Cryobiology and Cryomedicine, Academy of Sciences of the USSR, Kharkov. (Presented by Academician of the Academy of Medical Sciences of the USSR V. I. Struchkov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 6, pp. 729–731, June, 1978.     

Étude comparative de l'analyse spectrale de la fréquence cardiaque au cours de l'exercice sur ergocycle et de l'entraînement en judoHeart rate comparative study by spectral analysis between two exercises: ergocycle vs judo randori

Aim – Heart rate comparative study by spectral analysis between a 6 minutes judo randori et a 4 minutes ergocycle exercise at .Materials and methods – By ten male judokas, both time series were analyzed by short term Fourier transform (time/frequency analysis). Each 512 RR time series drawn from ECG was subdivided by Hanning windowing in 13 samples of 128 values (32 RR periods step). For each sample, both exercise types, means of the ten spectrograms have been computed, yielding two mean spectrograms for each sample.Results – 1) Despite a near maximal heart rate (HR) level between the two exercise types, the spectral energy computed from judo randori was significantly more important than ergocycle spectral energy. This phenomenon yields a qualitative effect of the exercise type (judo or ergocycle) on HRV. 2) the normalized spectral powers of low frequency and high frequency bands respectively, were not significantly different between both exercise types.Conclusion – The autonomie nervous control on HR would depend rather on exercise load than on exercise type.     

Contractile protein expression in bladder smooth muscle is a marker of phenotypic modulation after outlet obstruction in the rabbit model

PURPOSE: We determined changes in contractile protein expression before and after the relief of partial bladder outlet obstruction in the rabbit model and assessed their potential role as predictors of recovery. MATERIALS AND METHODS: We examined the ratio of the smooth muscle myosin heavy chain isoforms SM2-to-SM1, caldesmon isoform expression and bladder function in obstructed and unobstructed adult rabbit bladders. Cystometry, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis were done to determine changes in bladder function and contractile protein expression. RESULTS: Overall we observed significant correlation of bladder weight with the SM2-to-SM1 ratio (p <0.05). Regardless of the duration of obstruction (up to 10 weeks) the ratio appeared to stabilize around a value comparable to that in fetal rabbit smooth muscle cells, suggesting a reversal of SM2 and SM1 expression to a level similar to that at the fetal stage. The pattern of h and l-caldesmon isoform expression showed an increase in l-caldesmon expression in obstructed bladders. Except for decreased leak point pressure in the obstructed group we noted no statistically significant urodynamic changes in bladder capacity or compliance. CONCLUSIONS: There is significant correlation of bladder weight, which is the best known marker of obstruction, with the SM2-to-SM1 ratio. The myosin heavy chain isoform expression ratio appears to be an indicator of phenotypic modulation in bladder smooth muscle before and after the relief of bladder outlet obstruction. Thus, it may be useful as a marker of bladder dysfunction and predictor of functional recovery. Regression to a fetal pattern of protein expression may suggest irreversible damage to smooth muscle cells, possibly limiting recovery.     

Proceedings of the Australian Physiological and Pharmacological Society Symposium: New Frontiers in Muscle ResearchHybrid skeletal muscle fibres: a rare or common phenomenon?

1. The main aim of the present review is to raise awareness of the molecular complexity of single skeletal muscle fibres from "normal" and "transforming" muscles, in recognition of the many types of hybrids that have been observed in vertebrate skeletal muscle. The data used to illustrate various points made in the review were taken from studies on mammalian (mostly rat) and amphibian muscles. 2. The review provides a brief overview of the pattern and extent of molecular heterogeneity in hybrid muscle fibres and of the methodological problems encountered when attempting to identify and characterize such fibres. Particular attention is given to four types of skeletal muscle hybrids: (i) myosin heavy chain (MHC) hybrids; (ii) mismatched MHC-myosin light chains (MLC) hybrids; (iii) mismatched MHC-regulatory protein hybrids; and (iv) hybrids containing mismatched MHC-sarcoplasmic reticulum protein isoforms. 3. Some of the current ideas regarding the functional significance, origin and cognitive value of hybrid fibres are examined critically.     

Synaptic plasticity in the medial vestibular nuclei: role of glutamate receptors and retrograde messengers in rat brainstem slices

The analysis of cellular-molecular events mediating synaptic plasticity within vestibular nuclei is an attempt to explain the mechanisms underlying vestibular plasticity phenomena. The present review is meant to illustrate the main results, obtained in vitro, on the mechanisms underlying long-term changes in synaptic strength within the medial vestibular nuclei. The synaptic plasticity phenomena taking place at the level of vestibular nuclei could be useful for adapting and consolidating the efficacy of vestibular neuron responsiveness to environmental requirements, as during visuo-vestibular recalibration and vestibular compensation. Following a general introduction on the most salient features of vestibular compensation and visuo-vestibular adaptation, which are two plastic events involving neuronal circuitry within the medial vestibular nuclei, the second and third sections describe the results from rat brainstem slice studies, demonstrating the possibility to induce long-term potentiation and depression in the medial vestibular nuclei, following high frequency stimulation of the primary vestibular afferents. In particular the mechanisms sustaining the induction and expression of vestibular long-term potentiation and depression, such as the role of various glutamate receptors and retrograde messengers have been described. The relevant role of the interaction between the platelet-activating factor, acting as a retrograde messenger, and the presynaptic metabotropic glutamate receptors, in determining the full expression of vestibular long-term potentiation is also underlined. In addition, the mechanisms involved in vestibular long-term potentiation have been compared with those leading to long-term potentiation in the hippocampus to emphasize the most significant differences emerging from vestibular studies. The fourth part, describes recent results demonstrating the essential role of nitric oxide, another retrograde messenger, in the induction of vestibular potentiation. Finally the fifth part suggests the possible functional significance of different action times of the two retrograde messengers and metabotropic glutamate receptors, which are involved in mediating the presynaptic mechanism sustaining vestibular long-term potentiation.     

早期气管切开对老年重型颅脑损伤术后防止肺部感染的影响

目的研究老年重型颅脑损伤术后早期气管切开对防止肺部感染的影响。方法选择急诊开颅手术后老年重型颅脑损伤患者120例随机分为两组，A组为早期气管切开（即切开时间在术后24h以内）60例。B组为未行早期气管切开（即切开时间在术后24h以后）60例；所有患者术后均用头孢三代、半合成青霉素静滴预防感染，出现肺部感染者均行痰培养药敏试验，选择敏感药物进行治疗。结果75例患者出现肺部感染。其中A组21例，有16例感染控制，感染控制时间4～10d，平均6．5d；B组54例，有16例感染控制，感染控制时间为10～20d，平均17．2d；A组肺部感染率和控制感染平均时间均显著低于B组（P〈0．01），同时A组感染控制率亦显著高于B组（P〈0．05）。结论早期气管切开能有效防止老年重型颅脑损伤术后并发的肺部感染。     

当药片重金属及砷盐的含量测定

目的:检测当药片的重金属及砷盐的含量。方法:中国药典2000版一部附录重金属及砷盐检查法。结果:15批当药片中重金属含量<20.0 mg/g;砷盐含量<2.0 mg/g。结论:当药片中的重金属和砷盐符合标准。     

石蜡包埋B细胞淋巴瘤组织克隆性IgH基因重排的检测

目的：探讨克隆性免疫球蛋白重链第三互补决定簇区（IgHCD43）基因重排在B细胞非霍奇金淋巴瘤（B－NHL）诊断方面的价值。方法：采用半巢式PCR、聚丙烯酰胺凝胶电泳（PAGE）及银染技术,检测38例B－NHL、4例T－NHL及10例慢性扁桃腺炎,经福尔马林固定、石蜡包埋病理组织的克隆性IgHCDR3重排。结果：29例B－NHL及1例免疫组化未能明确细胞来源的NHL克隆性IgHCDR3重排阳性;4例T－NHL及10例慢性扁桃腺炎克隆性IgHCDR3重排阴性。结论：克隆性IgHCDR3重排可作为B－NHL与反应性增生鉴别的特生标志,大部分情况下可作为系分化标志。     

The manganese and iron superoxide dismutases protect Escherichia coli from heavy metal toxicity

Superoxide dismutases (SODs) are vital components that defend against oxidative stress through decomposition of superoxide radical. Escherichia coli contains two highly homologous SODs, a manganese- and an iron-containing enzyme (Mn-SOD and Fe-SOD, respectively). In contrast, a single Mn-SOD is present in Bacillus subtilis. In E. coli, the absence of SODs was found to be associated with an increased sensitivity to cadmium, nickel and cobalt ions. Mutants lacking either sodA or sodB exhibited metal resistance to levels comparable to that of the wild-type strain. Although sod-deficient mutant cells were more resistant to zinc than their wild-type counterpart, no differences between the strains were observed in the presence of copper. In B. subtilis, the sodA mutation had no effect on cadmium and copper resistance. These results suggest that intracellular generation of superoxide by cadmium, nickel and cobalt is toxic in E. coli. They support the participation of sod genes in its protection against metal stress.