Radiological evaluation of bone status in the jaw and in the vertebral column in a group of women

Vertebral bone mineral content was determined in a group of 56 women, ages 30–62. These measurements were compared with the status of supporting bone in the jaws (alveolar, molar and bicuspid) and with gingival health. There was a significant decline in vertebral bone mineral content from the pre- to post-menopausal group. Molar and bicuspid measurements were highly correlated. There was some association between lumbar bone mineral content and molar bone status for postmenopausal women. For postmenopausal women, the cases of greatest percent bone loss in alveolar crest were associated with lower lumbar bone mineral content. Gingival health did not confound the bone status measurements. The 56 subjects did not exhibit the degree of reduction in bone density that is observed in the general population. Further investigation using these radiographic techniques may reveal a link between substantial bone loss in the jaw and moderate to severe bone loss in the lumbar vertebrae.     

Cloning and characterization of the Methylobacterium extorquens polyhydroxyalkanoic-acid-synthase structural gene

A cosmid gene bank of partially EcoRI-digested genomic DNA from Methylobacterium extorquens IBT no. 6 was screened for DNA fragments restoring polyhydroxyalkanoic-acid (PHA) accumulation in the PHA-negative mutant Alkaligenes eutrophus H16 PHB^–4. The M. extorquens PHA-synthase structural gene phaC _Mex was mapped on a 23-kbp EcoRI fragment by complementation studies, by hybridization experiments with heterologous DNA probes from A. eutrophus H16 encoding for phaA, phaB and phaC and by nucleic acid sequence analysis. Evidence for the presence of genes for a -ketothiolase or an acetoacetyl-coenzyme A reductase on this fragment was not obtained. The nucleotide sequence of a 3.7-kbp region was obtained. It contained the entire 1.815-kbp phaC _Mex plus approximately each 900-bp upstream and downstream of phaC _Mex. PhaC _Mex encoded a protein of 605 amino acods with a relative molecular mass (M_r) of 66742, which exhibited 38.1% amino acid identity with the A. eutrophus PHA synthase. Determination of the N-terminal amino acid sequence of an M_r 65 000 protein, which was enriched concomitantly with the purification of PHA granules in sucrose gradients, revealed a sequence that was identical with the amino acid sequence deduced from the most probable translation start codon except for a valine, which was obviously removed post-translationally. Enzyme analysis, which was done with the native gene and a phaC _Mex -lacZ fusion gene, gave no evidence for expression of phaC _Mex in Escherichia coli.     

The amylase-secreting cells of the stomach of the scallop, Pecten maximus: ultrastructural, immunohistochemical and immunocytochemical characterizations

(1) alpha-amylase was extracted and purified from the stomach/digestive gland complex of the scallop Pecten maximus and an anti-serum was induced against the purified amylase by rabbit immunization. (2) The anti scallop amylase was used to localize the amylase-secreting cells in the stomach of Pecten maximus by immunofluorescence and immunogold labelling. The amylase-secreting cells are glandular cells particularly numerous in the main sorting area of the stomach. Their secretory granules were found strongly positive for anti-amylase. Three types of glandular cells were observed, actually corresponding to the three stages of the glandular-cell activity, synthesis, secretion and excretion. (3) The synthesizing cell shows the characteristic features of a protein-synthesizing cell: a conspicuous nucleolus and abundant granular endoplasmic reticulum. In the secretory cell, the secretory granules are formed by the Golgi apparatus and accumulate in the apical part of the cell. The secretory cell is filled with two types of secretory granules which are released in the stomach lumen by apocrine excretion. (4) The present study brings the first demonstration of the synthesis and extracellular release of amylase by glandular cells of the stomach epithelium of a bivalve.     

Concerning the mechanism of increased thermogenesis in rats treated with dehydroepiandrosterone

Dehydroepiandrosterone (DHEA) treatment of rats decreases gain of body weight without affecting food intake; simultaneously, the activities of liver malic enzyme and cytosolic glycerol-3-P dehydrogenase are increased. In the present study experiments were conducted to test the possibility that DHEA enhances thermogenesis and decreases metabolic efficiency via trans-hydrogenation of cytosolic NADPH into mitochondrial FADH₂ with a consequent loss of energy as heat. The following results provide evidence which supports the proposed hypothesis: (a) the activities of cytosolic enzymes involved in NADPH production (malic enzyme, cytosolic isocitrate dehydrogenase, and aconitase) are increased after DHEA treatment; (b) cytosolic glycerol-3-P dehydrogenase may use both NAD⁺ and NADP⁺ as coenzymes; (c) activities of both cytosolic and mitochondrial forms of glycerol-3-P dehydrogenase are increased by DHEA treatment; (d) cytosol obtained from DHEA-treated rats synthesizes more glycerol-3-P during incubation with fructose-1,6-P₂ (used as source of dihydroxyacetone phosphate) and NADP⁺; the addition of citratein vitro further increases this difference; (e) mitochondria prepared from DHEA-treated rats more rapidly consume glycerol-3-P added exogenously or formed endogenously in the cytosol in the presence of fructose-1,6-P₂ and NADP⁺.     

Solubilization and reconstitution of the mitochondrial peptide-sensitive channel

In addition to the voltage-dependent anion channel (VDAC), mitochondrial outer membranes contain a cationic channel of large conductance, which is blocked by a mitochondrial addressing peptide (peptide-sensitive channel, PSC). Bovine adrenal cortex mitochondria were solubilized in 1.5% octyl -glucoside, and membrane vesicles were reconstituted by slow dilution with a low ionic strength buffer. The reconstituted vesicles contained a functional channel possessing the electrical characteristics of the cationic channel, including its sensitivity to the mitochondrial addressing peptide. Important features of the described protocol are the nature of the detergent, its concentration, and the addition of glycerol during the whole procedure. No solubilization could be observed in the presence of cholate.     

Characterization of a strain of cerebral endothelial cells derived from goat brain which retain their differentiated traits after long-term passage

Summary A strain of cerebral endothelial cells was established from isolated cortical microvessels of caprine brain. These cells, which are referred to as ECl cells, can be routinely subcultured to 32 passages without the loss of differentiated morphologic and immunologic traits. The ability to routinely subculture ECl cells is an important asset, given that isolated cerebral endothelial cells in mammals generally lose their differentiated traits after only 2 to 3 passages. ECl cells were shown to contain Factor VIII-related antigen, which is a specific marker for cells of endothelial origin. ECl cells morphologically demonstrated a scarcity of pinocytotic vesicles on their apical surfaces, a lack of trans-cytoplasmic vesicles, and the ability to form in culture confluent monolayers with tight junctional complexes. Therefore, ECl cells possess specific antigenic and ultrastructural features which classify them as being small vessel endothelial cells of the blood-brain barrier type. Cytogenetic evaluation of ECl cells demonstrated a normal female goat 60,XX karyotype and confirmed the apparent non-transformed nature of ECl cells due to the lack of chromosome abnormalities or rearrangements. Using scanning electron microscopy, ECl cells were also shown to form confluent monolayers on mixed nitrocellulose filters, a feature that will enable the development of an in vitro system to study trans-endothelial transport. Given that ECl cells are readily subcultured and grow well on nitrocellulose filters, and that they resemble cerebral endothelium in vivo, it seems evident that ECl cells can be used as a versatile model for the study of blood-brain barrier function, regulation, and pathology.     

A dominant sulfhydryl-containing protein in the outer membrane of Neisseria gonorrhoeae.

By using a method that labels sulfhydryl-containing proteins in situ, we have detected a major outer membrane protein of Neisseria gonorrhoeae at 41 kDa. A protein of this molecular mass has not previously been shown to be a major outer membrane protein in gonococci. In addition, a minor protein rich in cysteinyl residues was detected at 31.5 kDa.     

Regulation of taurine transport in Ehrlich ascites tumor cells

Summary Taurine influx is inhibited and taurine efflux accelerated when the cell membrane of Ehrlich ascites tumor cells is depolarized. Taurine influx is inhibited at acid pH partly due to the concomitant depolarization of the cell membrane partly due to a reduced availability of negatively charged free carrier. These results are in agreement with a 2Na, 1Cl, 1taurine cotransport system which is sensitive to the membrane potential due to a negatively charged empty carrier. Taurine efflux from Ehrlich cells is stimulated by addition of LTD4 and by swelling in hypotonic medium. Cell swelling in hypotonic medium is known to result in stimulation of the leukotriene synthesis and depolarization of the cell membrane. The taurine efflux, activated by cell swelling, is dramatically reduced when the phospholipase A₂ is inhibited indirectly by addition of the anti-calmodulin drug pimozide, or directly by addition of RO 31-4639. The inhibition is in both cases lifted by addition of LTD₄. The swelling-induced taurine efflux is also inhibited by addition of the 5-lipoxygenase inhibitors ETH 615-139 and NDGA. It is concluded that the swelling-induced activation of the taurine leak pathway involves a release of arachidonic acid from the membrane phospholipids and an increased oxidation of arachidonic acid into leukotrienes via the 5-lipoxygenase pathway. LTD₄ seems to act as a second messenger for the swelling induced activation of the taurine leak pathway either directly or indirectly via its activation of the Cl^– channels, i.e., via a depolarization of the cell membrane.     

Detection of a molecular deletion at the DXS732 locus in a patient with X-linked hypohidrotic ectodermal dysplasia (EDA), with the identification of a unique junctional fragment.

X-linked hypohidrotic ectodermal dysplasia (EDA) has been localized to the Xq12-q13.1 region. A panel of genomic DNA samples from 80 unrelated males with EDA has been screened for deletions at seven genetic loci within the Xq12-13 region. A single individual was identified with a deletion at the DXS732 locus by hybridization with the mouse genomic probe pcos169E/4. This highly conserved DNA probe is from locus DXCrc169, which is tightly linked to the Ta locus, the putative mouse homologue of EDA. The proband had the classical phenotype of EDA, with no other phenotypic abnormalities, and a normal cytogenetic analysis. A human genomic DNA clone, homologous to pcos169E/4, was isolated from a human X-chromosome cosmid library. On hybridization with the cosmid, the proband was found to be only partially deleted at the DXS732 locus, with a unique junctional fragment identified in the proband and in three of his maternal relatives. This is the first determination of carrier status for EDA in females, by direct mutation analysis. Failure to detect deletion of the other loci tested in the proband suggests that the DXS732 locus is the closest known locus to the EDA gene. Since the DXS732 locus contains a highly conserved sequence, it must be considered to be a candidate locus for the EDA gene itself.