Observations and comments on the reliability of muscle reconstruction in fossil vertebrates

In Canis and Ursus the largest proportion of attachments of muscles of the shoulder and brachium on the scapula and humerus is direct; fewer attachments are aponeurotic or tendinous. In both genera most attachments can be associated with superficial osteological features (scars or delimitable surfaces); attachments that lack such features are direct. Most aponeurotic attachments are associated with rugose scarring whereas tendinous attachments are often associated with smooth surfaces. Although most attachments can be associated with osteological features the areal extent of attachment is often not inferrable from the bone. The inference of muscle size or functional significance from osteological features is problematic. The amount of myological information that can be deciphered from the osteology in Canis and Ursus is greater than that reported for particular members of other vertebrate groups which suggests that there may be differences in the degree to which muscles can be reconstructed from superficial osteology alone. Nonetheless, even in mammals such as the Carnivora, detailed muscular reconstructions in extinct taxa cannot be achieved without reference to the musculature of extant relatives. Such reconstructions rely on assumptions, that often have not been adequately tested, regarding the similarity of musculature in closely related taxa. This testing and well corroborated hypotheses of phylogenetic relationship are essential for the evaluation of the accuracy of reconstructions of the musculature in fossil vertebrates.     

The role of active forms of oxygen in platelet aggregation and deaggregation

The effect of hydrogen peroxide on ADP-induced platelet aggregation in the presence of active oxygen species scavengers was studied. It was shown that the superoxide radical and singlet oxygen, alongside with hydrogen peroxide, may play a role in platelet interactions.     

The secreted form of the epidermal growth factor receptor. Characterization and crystallization of the receptor-ligand complex

A protein composed of the external domain of the epidermal growth factor (EGF) receptor is secreted by A431 human tumor cells. The soluble receptor protein was isolated in bulk quantities from cell culture supernatants. It has an intact ligand binding site, exists in a 93-kDa monomeric form, and does not undergo oligomerization upon ligand binding; thus the receptor dimerization reported for the EGF holoreceptor appears not to be a function of its external domain. The unique system of a physiological soluble receptor was utilized for a crystallization study. Crystals were obtained but only in the presence of the ligand. They contained (in equimolar amounts) receptor as well as EGF. The crystals belong to the tetragonal space group P4(3)2(1)2 or P4(1)2(1)2 with unit cell dimensions a = b = 118 A, c = 202 A. The packing density parameter was 3.55 A3/dalton, indicating the asymmetric unit to consist of one receptor-ligand complex.     

Effects of 4-methyluracil and carnosine on healing of skin wounds in rats

In experiments in vivo and in vitro the authors studied antioxidative properties of 4-methyluracil and carnosine, their capacity to inhibit sex and accelerate healing of skin wounds. 4-methyluracil and carnosine discover almost the same capacity to decrease in the tissues of the wound and the blood serum in the formation of various intermediate products of free radical oxidation. Data are given on the study of the dynamics of wound healing after a 5-day treatment with equimolar quantities.     

A histochemical analysis of the oxidative-reductive enzymes in the cardiomyocytes of mature and old rats following low-dose external gamma irradiation

The effect of gamma rays in low dose (0.5 Gy) on enzymes activity of glycolysis, tricarboxylic acid cycle, diaphorases in cardiomyocytes of adult and old albino rats at 3-, 10- and 30-day after irradiation was studied. It was established that the diaphorases activity decreased, the lactate dehydrogenase activity increased whereas that of other tricarboxylic acid cycle enzymes underwent phase changes. In result discoordination of redox enzymes in cardiomyocytes of rats hypoxic state develops. The question of the age sensitivity of heart to irradiation in low dose is discussed.     

Fine mapping of the MLK-3 gene within 11q13 and its exclusion as the MEN1 susceptibility gene

MLK-3 kinase is a widely expressed serine/ threonine kinase that bears multiple protein interaction domains and regulates signals mediated by the stress-responsive pathway. Thus, MLK-3 signaling affects numerous cellular processes, raising the possibility that MLK-3 might play a role in oncogenesis. In this report, we describe the fine mapping of the MLK-3 gene within the 11q13.1 chromosomal region. By integrating data from somatic cell hybrids and double color fluorescence in situ hybridization on metaphase chromosomes and DNA fibers, MLK-3 has been assigned approximately 1 Mb telomeric of PYGM, close to the D11S546 locus. Since the MEN1 susceptibility locus is also located within the 11q13.1 region, we have carried out Southern and Northern blot analyses, as well as protein truncation assays to establish whether abnormalities in MLK-3 lead to the development of this familial cancer syndrome. Our observations exclude MLK-3 as the MEN1 gene. Received: 25 September 1996 / Revised: 16 December 1996     

Incorporation of monoclonal antibodies into cells by osmotic permeabilization. Effect on cellular metabolism

Incorporation of asparagine synthetase-specific monoclonal antibodies into L5178Y D10/R (L-asparaginase-resistant) murine lymphoma cells by osmotic lysis of pinocytic vesicles was used to evaluate the potential of the technique for macromolecular incorporation for metabolic studies. Nonspecific effects of the incorporation procedure included temporary inhibition of protein and DNA synthesis by 80-85% and a transitory loss of membrane integrity. Cells incorporated with an antibody inhibitory to tumor cell asparagine synthetase showed increased dependence upon an exogenous source of asparagine in the culture medium, while cells incorporated with a control antibody were not affected. These studies demonstrated that incorporation of inhibitory monoclonal antibodies into cells can be used to study the short term metabolic role of specific enzymes; however, the metabolic effects induced by the specific macromolecule must be evaluated within the context of the nonspecific effects caused by the osmotic treatment required for incorporation.