The effect of vitamin A on limb regeneration in Rana temporaria

Previous experiments in which vitamin A has been administered to developing or regenerating limbs have shown that different limb axes are affected. In regenerating axolotl limbs, serial reduplications in the proximodistal axis are produced. In the developing chick limb bud, mirror-imaged reduplications in the anteroposterior axis are produced. Results reported here on Rana temporaria limb buds reveal that vitamin A causes both effects to occur. That is, limbs are both serially reduplicated in the proximodistal axis and mirror imaged in the anteroposterior axis. Time and concentration effects are explored and the significance of these results for our current understanding of axial organisation in limbs is discussed.     

Behavior of lactating rats in a dual-chambered maternity cage

Videotape sampling of behavior in a dual-chambered apparatus indicates that the continuous monitoring of the amount of time a mother spends in the cage with its litter can be taken as a valid reflection of maternal behavior. Nursing is the principal behavior of lactating females while in the compartment with their litters; lying still, consummatory behavior, and activity occur with greater frequency in the cage away from the litter. Both the time that mothers spend with their litters and nursing behavior displayed a 24-hr rhythm with crest values occurring during the period of light.     

Isolation of ouabain-resistant human diploid fibroblasts

Seventeen clones resistant to the cytotoxic action of ouabain were isolated in culture by direct selection from 5 independent strains of diploid human fibroblasts. Resistant clones were recovered at frequencies on the order of 10^?7 per wild type cell selected from populations treated with the mutagen EMS, but no resistant cells were detected among 10⁸ unmutagenized cells. Most selected clones remained ouabain-resistant following further propagation in the absence of drug. The growth of wild type cells was inhibited by 50% at ouabain concentrations of 2–5 × 10^?8 M, while resistant clones required 15–180 fold higher drug concentrations to cause equivalent inhibition. Ouabain-resistant clones showed increased resistance of K+ transport function to ouabain inhibition that paralleled their increased resistance to growth inhibition. Initial experiments suggest that under selective conditions the resistant diploid fibroblasts differ significantly from wild type in binding of ³H-ouabain per unit surface area. The ouabain-resistant cells were similar to wild type in transport properties unrelated to ouabain inhibition. Resistant cells had normal karyotypes and senesced with a lifespan similar to control clones. The ouabain-resistant phenotypes of these diploid human fibroblast isolates apparently reflect point mutations that specifically affect the Na+/K+ transport ATPase with respect to ouabain-binding and/or response to bound ouabain.     

Immunologic and clinical improvement of progressive coccidioidomycosis following administration of transfer factor

Three patients with progressive coccidioidomycosis were given preparations of transfer factor (TF). Adverse reactions to TF were minimal. Following TF administration two of these patients had prolonged clinical remissions in their coccidioidal disease. Cellular immune responses were sequentially evaluated by coccidioidininduced delayed-type skin tests, lymphocyte blast transformation and macrophage inhibition factor production (MIF). These three patients each exhibited different cellular immune patterns before and after TF administration. Two patients converted their coccidioidin skin tests, and one converted lymphocyte transformation response to coccidioidin. Also, TF apparently favorably affected the MIF response in all three patients.     

严重缺碘对体质及遗传性状影响的研究

对严重缺碘地区一个容貌特殊,身材较矮,智力低下的人群进行了体质特征及遗传性状的研究,并与国内有关本地区的调查资料进行了对照,提出人类体质特征和遗传性状除与人种、地理环境异同直接相关外,人体不可缺少的微量元素的摄入水平在一定程度上对其也产生影响。并且认为同一人种、民族居住同一地理位置所产生的体质差异应从水文、地质、生活方式、生活水平的不同进行综合分析。     

Determination of mercury in human serum and packed blood cells by neutron activation analysis

A method is described for the determination of mercury in human blood serum and packed blood cells employing neutron activation analysis. Great attention was devoted to the collection and manipulation of the samples. The accuracy and precision of the method were tested by analyzing biological reference materials and by comparing the concentrations measured in a number of serum samples to those obtained by another, independent technique (cold vapor atomic absorption spectrometry) in the same samples. The article reports the levels measured in blood serum and packed blood cells samples from 15 adult volunteers, as well as the figures determined in a “second-generation” biological reference material (freeze-dried human serum), prepared and conditioned at the University of Ghent.     

In situ response to vinka alkaloids by microtubules in cultured post-implanted mouse embryos

The response of microtubules to treatment with vinca alkaloids was investigated in vivo and in situ in the embryonic nervous system of mice. For this purpose we used rotatory cultures of post-implanted embryos in a serum medium containing the alkaloid combined with immunofluorescence using a tubulin-specific polyclonal antibody on high molecular weight polyethylene glycol embedded semithin sections. In mitotic cells, kinetochore microtubules were seen to be more resistant to the action of vinca alkaloids than interpolar microtubules. Increasing drug concentrations induced an increasing rate of mitosis together with an increasing rate of disassembly of the cytoplasmic microtubule complex, suggesting a probable relation between these events. In bipolar neuroepithelial cells at interphase, a small pool of microtubules was resistant to the vinca alkaloids. These microtubules were located near the centriolar apparatus associated with the primary cilium; they were short, curly and bent. Disruption of the cytoplasmic microtubule complex did not alter the shape of the bipolar neuroepithelial cells. In the axonal profiles, a drug-stable pool of microtubules were not disrupted by the alkaloids and were also short. They seem to act as microtubule organizing centres. These observations suggest vinca alkaloids seem to act in vivo much more by inducing, at a given concentration, the disruption of a particular group of microtubules without altering the others. The fact that these drugs affect the number, but not the length, of the microtubules raises the hypothesis that these drugs act on microtubules by a mechanism similar to that described as "dynamic instability".