Immunohistochemistry of thyroid hormones as a functional parameter in thyroid pathology

The authors study by means of immunoperoxidase method the pattern of thyroglobulin, triiodothyronine and thyroxine distribution in 58 cases of thyroid disorders: 15 euthyroid goiters, 10 Graves' disease, 7 Hashimoto's thyroiditis, 11 folliculo-papillary carcinomas (6 primary tumors and 5 lymph node metastases), 8 follicular carcinomas, 4 anaplastic carcinomas and 3 medullary carcinomas. Thyroglobulin, triiodothyronine and thyroxine were present in most of the thyroid disorders, excepting anaplastic and medullary carcinomas. Thyroglobulin and thyroxine were localized both in the follicular epithelium and in the colloid, whereas triiodothyronine was present especially in the follicular cells. The thyroid hormones distribution in benign lesions is rather similar. In carcinomas, the pattern of thyroglobulin, triiodothyronine and thyroxine is more heterogeneous, but generally the triiodothyronine distribution is similar to that of thyroglobulin. In some carcinomas, triiodothyronine and thyroxine showed a weak or negative immunostaining. The immunoperoxidase method is a valuable tool in the study of functional disturbances in the thyroid pathology and in the diagnosis of thyroid carcinoma metastases as well. Positive thyroid hormones staining clearly indicates the thyroid origin of metastases.     

Turnover of plant lineages shapes herbivore phylogenetic beta diversity along ecological gradients

Understanding drivers of biodiversity patterns is of prime importance in this era of severe environmental crisis. More diverse plant communities have been postulated to represent a larger functional trait‐space, more likely to sustain a diverse assembly of herbivore species. Here, we expand this hypothesis to integrate environmental, functional and phylogenetic variation of plant communities as factors explaining the diversity of lepidopteran assemblages along elevation gradients in the Swiss Western Alps. According to expectations, we found that the association between butterflies and their host plants is highly phylogenetically structured. Multiple regression analyses showed the combined effect of climate, functional traits and phylogenetic diversity in structuring butterfly communities. Furthermore, we provide the first evidence that plant phylogenetic beta diversity is the major driver explaining butterfly phylogenetic beta diversity. Along ecological gradients, the bottom up control of herbivore diversity is thus driven by phylogenetically structured turnover of plant traits as well as environmental variables.     

Autoradiographic localization of high affinity uptake sites for 3H-D-aspartate in the rat olfactory bulb

In order to reveal excitatory amino acid-ergic neuronal connections in the rat olfactory bulb, uptake sites for the tritiated D-aspartic acid were analyzed by high resolution autoradiography. Light microscopy revealed both cellular and terminal-like uptake. Based on electron microscopy, overwhelming majority of the cellular uptake was assigned to glial cells. A fairly high number of labelled terminals appeared in the surroundings of the mitral cell somata, within the deepest portion of the external plexiform layer, in the internal plexiform layer and in the outer half of the granule cell layer. Labelled terminals synapsed onto likely granule cell dendrites or spines, at asymmetric membrane thickenings. These results suggest that, although the output neurons may not utilize glutamic or aspartic acid as their transmitters, these amino acids may, however, contribute to the bulbar neurotransmission, as mediator substances of a subgroup of centrifugal fibers to the olfactory bulb.     

The plasma membrane of yeast protoplasts exposed to hypotonicity becomes porous but does not disintegrate in the presence of protons or polyvalent cations

Protoplasts of Saccharomyces cerevisiae swelled, lysed and disintegrated when exposed to hypotonic solutions at neutral pH. At pH 4.5 or lower the hypotonically treated protoplasts did not disintegrate and they retained their intracellular proteins, nucleic acids and nucleotides. However, they became leaky for K+ and Ca2+, indicating that pores had been created in the surface membrane, relaxing the osmotic stress. Upon readjustment of pH to neutral, the hypotonically treated protoplasts released the intracellular content and disintegrated. Also, at low pH, protoplasts did not swell in isotonic ammonium acetate and were refractory to the permeabilizing effect of nystatin and to lysis with low concentrations of detergents. Protoplasts were similarly protected against lysis and disintegration by hypotonic treatment or by detergents, even at neutral pH, if the incubation media contained polyvalent cations, especially Zn2+, La3+, spermine, and Ca2+ chelated with EDTA. The protoplasts exposed to hypotonic stress at low pH did not respire and could not regenerate into viable cells. Effects of H+ and polyvalent cations on intramembrane forces acting between molecules of membrane phospholipids are considered along with possible changes in interactions between membrane proteins.     

Model-based relationship between physicochemical properties and inhibitory potency of alkylating 2-furylethylenes on yeast glycolysis

Inhibitory effects of 35 2-furylethylenes, non-specific alkylating agents, on glycolysis in a respiratory mutant of Saccharomyces cerevisiae were correlated with their 1-octanol/water partition coefficients and the rate constants for reaction with 2-mercaptoacetic acid using physiologically based models. The simplest model explaining the data satisfactorily consists of two-step drug-receptor interaction involving reversible formation of a structurally non-specific non-covalent complex stabilized later covalently. The concentration of the free drug in the receptor surroundings was related to its initial concentration in external medium via a simple form of a disposition function constructed on the basis of time hierarchy of passive membrane transport, non-covalent binding to cell constituents and metabolic inactivation of the drug.     

Cultured fetal rat pituitaries kept in synthetic medium are able to initiate synthesis of trophic hormones

Summary An immunohistochemical study was performed to determine the capacity of early fetal pituitaries to differentiate into specific hormone-synthesizing tissue in the absence of any influence from the central nervous system. Rathke's pouches from rats were removed from their juxtadiencephalic position on day 11 and 12 of gestation and maintained for 2–7 days in a chemically defined culture medium (M 199) without antibiotics and serum supplementation. The immunocytochemical observations provided evidence for the differentiation of ACTH-, TSH-gb-, LH-gb-, FSH-gb-, GH- and PRL-synthesizing cells in the isolated organ cultured from 11 to 12-day-old pituitary primordia. The appearance of specific hormone-synthesizing cells in vitro displayed a delay of 1.5–2 days compared to the day of appearance in vivo, however, the sequential order of developmental events occurred as observed in vivo. The present results suggest that endocrine or neuroendocrine signals are not required for the expression of specific secretory functions of fetal pituitaries, at least at an age of 11–12 days.     

Competition in the gradostat: the role of the communication rate

In this paper we study a mathematical model of competition between two species of microorganisms for a single limiting nutrient in a laboratory device called a gradostat. A gradostat consists of several (we consider only two) chemostats (CSTR's) connected together so that material can flow between the vessels in such a way that a nutrient gradient is established. Our model is a slightly modified version of one considered recently by Jäger et al. [3], in that the rate of exchange of material between the two vessels (the communication rate) is allowed to differ from the dilution rate. The outcome of competition turns out to be surprisingly sensitive to variation of the communication rate. We identify several coexistence regimes in parameter space and describe a method for obtaining operating diagrams for given pairs of competing microorganisms.Research supported in part by NSF Grant DMS 8521605