Physiology of the ECL cells.

The enterochromaffin-like (ECL) cells of the oxyntic mucosa (fundus) of the stomach produce, store and secrete histamine, chromogranin A-derived peptides such as pancreastatin, and an unanticipated but as yet unidentified peptide hormone. The cells are stimulated by gastrin and pituitary adenylate cyclase activating peptide and suppressed by somatostatin and galanin. Choline esters and histamine seem to be without effect on ECL cell secretion. The existence of a gastrin-ECL cell axis not only explains how gastrin stimulates acid secretion but also may help to explore the functional significance of the ECL cells with respect to the nature and bioactivity of its peptide hormone. From the results of studies of gastrectomized/fundectomized and gastrin-treated rats, it has been speculated that the anticipated ECL-cell peptide hormone acts on bone metabolism.     

Marfan syndrome: exclusion of genetic linkage to five genes coding for connective tissue components in the long arm of chromosome 2

Summary Marfan syndrome represents a heterogeneous connective tissue disease, the symptoms arising in several tissues and organs. The defective gene(s) behind this autosomal dominant condition has not been found despite considerable research. The main targets of the research have been the genes coding for connective tissue components. Several of the candidate genes suspected to be defective in Marfan syndrome are located on the long arm of chromosome 2. These genes include a cluster of two genes coding for fibrillar collagens COL3A1 and COL5A2, and a third member of the collagen gene family: COL6A3. Furthermore, genes for elastin (ELN) and fibronectin (FN) are also located in this area of chromosome 2. We studied this chromosomal area using restriction fragment length polymorphism (RFLP) linkage analysis in five Finnish Marfan families with affected members in three generations. In two point linkage analyses, Lod scores of –3.192 ( = 0.1) to COL3A1, –1.683 ( = 0) to COL6A3 and –2.664 ( = 0.01) to FN were obtained, whereas the linkage analysis between elastin and the disease was non-informative (Lod score 0.444, = 0). With the multipoint linkage analysis that permits simultaneous examination of several loci and more efficient use of family data, we obtained an exclusion of all these loci as the site of the mutation leading to Marfan syndrome in these families.     

Glycosphingolipid expression in spontaneously aborted fetuses and placenta from blood group p women. Evidence for placenta being the primary target for anti-Tja-antibodies

A 12-week-old fetus and one 17-week-old fetus + placenta were obtained after spontaneous abortions from two women of blood group p. The 17-week-old fetus was dissected into intestine, liver, brain and residual tissue. Nonacid glycosphingolipid fractions were prepared from the tissues. Glycolipid characterization was carried out using thin layer chromatography immunostained with monoclonal antibodies and bacteria and by¹H NMR spectroscopy and mass spectrometry. In the placental fraction substantial amounts of globotetraosylceramide (P-antigen) and globotriaosylceramide (P^k-antigen) were identified. In contrast, the fetuses contained only trace amounts of these structures, as revealed by immunostaining. These results indicate that the primary target for the antibodies of the anti-Tj^a serum is the placenta tissue, resulting in termination of the pregnancy.     

Selenium as a growth factor for plankton algae in laboratory experiments and in some Swedish lakes

The growth requirements of inorganic and organic selenium (Se) for the dinoflagellate Peridinium cinctum fa. westii and the diatom Stephanodiscus hantzschii var. pusillus and eight species of green algae are demonstrated. A new mineral culture medium for P. cinctum is presented. Using P. cinctum as a test alga, bioassays were carried out on waters from a calciferous lake and from some acidified, fertilized, lime-enriched or humic lakes for determination of their contents of bioavailable forms of Se (bioactive Se). Some of the results were related to Tot-Se and selenite-Se, measured chemically, to pH and the occurrence of ambient phytoplankton. In calcium-rich Lake Erken (pH ～ 8) blooms and decline of algae coincided with decreases (from >70 to ～20 ng Se · l^?1) and increases (up to >80 ng · l^?1) of bioactive Se, indicating uptake and release of inorganic or organic forms of Se. Acidified lakes (pH < 5) generally demonstrated much lower concentrations of bioactive Se (<20 ng · l^?1) than neutral, fertilized, lime-enriched, slightly acidic or humic lakes (>20 ng · l^?1). The correlation between pH and bioactive Se was positive (r ～ 0.92; n = 7). The ecological importance of Se is suggested for some common species of phytoplankton.     

Microdensitometer system for microradiography

Summary A microdensitometer system for point measurements in areas down to a few square micrometers is described. The detector system is connected to an integrating digital voltmeter, constituting a very sensitive system. The digital output signals and a digital identification are registered on a recorder and on a tape punch, thus facilitating computer analysis.The precision of the equipment varied from 1.1 per cent, for low signal levels, to 0.3 percent for the highest signal levels. Stray light, the only important source of systematic errors, was found to influence the output signal level. Concerning determinations of the densities, however, a variation of the order of 1 per cent was only obtained for small areas with densities differing from that of the background.     

Microradiographic determination of lead in mineralized tissues

Summary A dichromatic contact microradiographic method is presented for quantitative microanalysis of lead in mineralized tissues utilizing the L absorption edges of lead. Sections of mineralized tissue with a thickness of about 100 are exposed to filtered molybdenum K and copper K radiation. Quantitative localization of lead is possible within small areas of the order of 50 ² with an accuracy of 25 · 10^–12g lead. The method has been applied to studies of long term accumulation of lead in bone tissue.     

Secretion of a heat-stable fungalβ-glucanase from transgenic,suspension-cultured barley cells

Transgenic plant cell cultures have a potential for production and secretion of important proteins and peptides. To assess the possibilities of using a stable barley suspension culture for secretion of heterologous proteins in active form, we expressed the cDNA of the thermostable-glucanase (EGI) ofTrichoderma reesei in barley suspension cells. The cDNA coding for EGI and its signal sequence was placed under the control of the CaMV 35S promoter and the construction was transferred to the cells by particle bombardment. Stably transformed lines were obtained by selecting for a cotransformed antibiotic resistance marker. The expression of EGI cDNA led to accumulation of EGI in the culture medium, as shown by analysis with EGI-specific antibodies. Enzymatic assays confirmed that the EGI secreted by the suspension cells retained its activity and thermostable character. Furthermore, it was shown that the enzyme produced by the transgenic suspension culture could be used for degradation of soluble-glucans during mashing.     

GenomEUtwin: a strategy to identify genetic influences on health and disease.

In this issue of Twin Research, we describe different facets of a European Community funded effort, GenomEUtwin, which capitalises on eight of the world's largest and best characterised twin registers and a multi-national population cohort, MORGAM. This international study, reaching beyond the geographical borders of Europe, is based on linkage and association strategies designed to identify genetic contributors to health and disease using integrated expertise of participating groups in genetics, epidemiology and biostatistics. By merging information from numerous epidemiological and genetic databases, GenomEUtwin will create an intellectual and technical infrastructure for future genetic epidemiological studies aiming to define genetic and life style risks for common human diseases.