Chromosomal studies of leukemic and preleukemic Fanconi's anemia patients

Summary Cytogenetic studies of three Fanconi's anemia patients are reported, one of the patients having erythroleukemia, the other two preleukemia. Clonal abnormalities were present in all three cases. Partial chromosomal duplication uncommon in other leukemias was observed. Partial duplication of the long arm of chromosome 3 has been observed in the present case of erythroleukemia examined as well as in a previously reported one.     

Evidence That a Precursor Glycoprotein Is Cleaved to Yield the Major Glycoprotein of Avian Tumor Virus

A glycoprotein designated pr90, which is recognized by anti-gp85 serum, is present in lysates of pulse-labeled transformed cells. Under chase conditions, a reduction in the level of labeled pr90 is observed concomitant with the appearance of labeled, cell-associated viral glycoprotein.     

Empirical risk of oligophrenia in siblings of proband-oligophrenics in populations with high levels of inbreeding]

An investigation is carried out on 214 patients with oligophreny with regard to the secondary risk of the same disease for their four sibs. All patients were divided into 4 groups according to etiological symptoms, and it was found that maximal risk of the secondary disease with oligophreny was for the sibs of probably genetic group, and minimal one--for the sibs of the exogenic group. Maximal resemblance in the degree of the defect in the pair of proband-sibs was found both in probably-genetic and presumably-genetic groups. The risk of secondary oligophreny was significantly higher in sibs-probands with relatively lower degree of weak-mindedness than in those with severe mental defects. The frequency of the secondary oligophreny amond sibs of the inbred origin (18.9%) was more than twice as high (P less than 0.001) as in those of outbred origin (8.3%).     

Biomedical implications from a morphoelastic continuum model for the simulation of contracture formation in skin grafts that cover excised burns

A continuum hypothesis-based model is developed for the simulation of the (long term) contraction of skin grafts that cover excised burns in order to obtain suggestions regarding the ideal length of splinting therapy and when to start with this therapy such that the therapy is effective optimally. Tissue is modeled as an isotropic, heterogeneous, morphoelastic solid. With respect to the constituents of the tissue, we selected the following constituents as primary model components: fibroblasts, myofibroblasts, collagen molecules, and a generic signaling molecule. Good agreement is demonstrated with respect to the evolution over time of the surface area of unmeshed skin grafts that cover excised burns between outcomes of computer simulations obtained in this study and scar assessment data gathered previously in a clinical study. Based on the simulation results, we suggest that the optimal point in time to start with splinting therapy is directly after placement of the skin graft on its recipient bed. Furthermore, we suggest that it is desirable to continue with splinting therapy until the concentration of the signaling molecules in the grafted area has become negligible such that the formation of contractures can be prevented. We conclude this study with a presentation of some alternative ideas on how to diminish the degree of contracture formation that are not based on a mechanical intervention, and a discussion about how the presented model can be adjusted.     

A biomechanical mathematical model for the collagen bundle distribution-dependent contraction and subsequent retraction of healing dermal wounds

A continuum hypothesis-based, biomechanical model is presented for the simulation of the collagen bundle distribution-dependent contraction and subsequent retraction of healing dermal wounds that cover a large surface area. Since wound contraction mainly takes place in the dermal layer of the skin, solely a portion of this layer is included explicitly into the model. This portion of dermal layer is modeled as a heterogeneous, orthotropic continuous solid with bulk mechanical properties that are locally dependent on both the local concentration and the local geometrical arrangement of the collagen bundles. With respect to the dynamic regulation of the geometrical arrangement of the collagen bundles, it is assumed that a portion of the collagen molecules are deposited and reoriented in the direction of movement of (myo)fibroblasts. The remainder of the newly secreted collagen molecules are deposited by ratio in the direction of the present collagen bundles. Simulation results show that the distribution of the collagen bundles influences the evolution over time of both the shape of the wounded area and the degree of overall contraction of the wounded area. Interestingly, these effects are solely a consequence of alterations in the initial overall distribution of the collagen bundles, and not a consequence of alterations in the evolution over time of the different cell densities and concentrations of the modeled constituents. In accordance with experimental observations, simulation results show furthermore that ultimately the majority of the collagen molecules ends up permanently oriented toward the center of the wound and in the plane that runs parallel to the surface of the skin.

     

Salt stress induced biometric and physiological changes in Solanum tuberosum L. cv. Bintje grown in vitro

Potato plants grown in vitro were subjected to different salt stresses by providing the salts NaCl, Na₂SO₄, MgCl₂ and MgSO₄ in different concentrations up to 300 mM. Salinity greatly affected the survival and the rooting of the plants. Shoot and root growth decreased with increasing salt concentrations. Under mild stress conditions, i.e. in conditions where the plant is able to adapt to the stress, the observed decrease was dependent upon the salt used. Under severe stress conditions, however, the decrease of the shoot and root growth was independent of the nature of the ions.     

Diel methane emission patterns from Scirpus lacustris and Phragmites australis

In mature Phragmites australis and Scirpus lacustris vegetated sediment methane was emitted almost exclusively by plant-mediated transport, whereas in unvegetated, but otherwise identical sediment, methane was emitted almost exclusively by ebullition. Diel variations in methane emission, with highest emission rates at daytime and emission peaks following sunrise, were demonstrated for Phragmites and Scirpus. The diel difference and magnitude of the emission peaks were much smaller for Scirpus than for Phragmites. In contrast to Phragmites, methane concentrations within Scirpus stems did not change significantly over the diel period. These patterns are consistent with a two-way transport mechanism for Phragmites (convective at daytime and diffusive at night-time) and an all day diffusive mechanism for Scirpus. The patterns could not be accounted for by diel variation in air and sediment temperature, plant transpiration, or photosynthetically coupled methane production. Comparison of the experimentally derived ratio of methane emission in helium and nitrogen under light and dark conditions with the theoretical derived ratio (calculated according to the kinetic theory of gases) confirmed the exploitation of the different transport mechanism for Phragmites and Scirpus. Methane emission from Phragmites correlated significantly with incident light, which probably drove the pressure differential associated with thermally induced convection. Decrease of the radial resistance of Scirpus stems for methane transport under light compared to dark conditions, in combination with morphological characteristics of the plant species, suggested that stomatal aperture, regulated by light, controls methane emission from Scirpus. Diel variation in bubble emission from the non-vegetated sediment coincided with sediment temperature changes. The results have important implications for sampling and scaling strategies for estimating methane emission from wetlands.