Familial DiGeorge syndrome and associated partial monosomy of chromosome 22

Summary Partial monosomy of 22q due to an unbalanced 4;22 translocation was seen in a 2-month-old male with Type I truncus arterious, dysmorphic features, and T-cell abnormalities. The family history revealed a previous sib with Type I truncus arteriosus, thymic aplasia, and parathyroid hypoplasia noted on postmortem examination, consistent with DiGeorge syndrome. Evaluation of the asymptomatic mother of these two patients revealed partial T-cell deficiency and the same unbalanced translocation with deletion of proximal 22qll. These findings provide further evidence that some cases of complete or partial DiGeorge syndrome are associated with monosomy of the proximal long arm of chromosome 22, and they may explain many, if not all, familial cases of the syndrome.Supported in part by National Foundation-March of Dimes Grant No. 2-161/C-331. Funds from the Texas Department of Health through PL94-278 National Genetic Diseases Act, from the Robert J. Kleberg, Jr. Center for Human Genetics, and USPHS Grant No. RR-05425.     

Pituitary receptors for gonadotropin-releasing hormone in relation to changes in pituitary and plasma luteinizing hormone in ovariectomized-hypothalamo pituitary disconnected ewes. I. Effect of changing frequency of gonadotropin-releasing hormone pulses

Studies were undertaken to determine if changes in the amplitude of luteinizing hormone (LH) pulses that occur in response to changes in the frequency of gonadotropin-releasing hormone (GnRH) pulses are due to an alteration in the number of GnRH receptors. Ewes were ovariectomized (OVX) and the hypothalamus was disconnected from the pituitary (HPD). Ewes were then given pulses of GnRH at a frequency of 1/h or 1/3 h. Two control groups were included: OVX ewes not subjected to HPD, and HPD ewes that were not OVX. At the end of one week of treatment, blood samples were collected to determine the amplitude of LH pulses. The treated ewes were killed just before the next scheduled pulse of GnRH, and the content of LH and number of GnRH receptors were measured in each pituitary. The amplitude of LH pulses was highly correlated with the amount of LH in the pituitary gland (r = 0.71, p less than 0.01), and both LH content and pulse amplitude (mean + SEM) were higher in ewes receiving GnRH once per 3 h (189.7 +/- 39.3 microgram/pituitary, 10.3 +/- 1.1 ng/ml, respectively) than in ewes receiving GnRH once per h (77.8 +/- 11.4 microgram/pituitary, 5.2 +/- 1.3 ng/ml). The pituitary content of LH was highest in the OVX ewes (260.2 +/- 57.4 micrograms/pituitary) and lowest in the nonpulsed HPD ewes (61.7 +/- 51.2 micrograms/pituitary). The number of GnRH receptors was similar in all groups, and was not correlated with any other variable.(ABSTRACT TRUNCATED AT 250 WORDS)     

Potentiation by Kainate of Excitatory Amino Acid Release in Striatum: Complementary In Vivo and In Vitro Experiments

The effect of kainate on extracellular levels of amino acids in corpus striatum was investigated in vitro and in vivo, to elucidate the mechanism underlying its neurotoxicity. Kainate increased extracellular glutamate and aspartate in both striatal slices in vitro and intact striatum in vivo, as previously reported. Both in vitro and in vivo, DL-threo-3-hydroxyaspartate increased extracellular glutamate and aspartate levels (to between 150 and 200% of basal), and also enhanced their kainate-evoked release. The action of kainate in vivo was reduced by prior frontal decortication, whereas in vitro the kainate-evoked responses were only slightly reduced by tetrodotoxin, and remained above control values. These results confirm that kainate increases extracellular glutamate and aspartate, and provide evidence that this is due to synaptic release evoked by an action on receptors on glutamatergic neurone terminals. These findings may be relevant to the understanding of epilepsy.     

Isolation and characterization of a large,neurite-associated glycoconjugate from neuroblastoma cells

A high molecular weight glycoconjugate has been isolated from neurite-producing neuronal tumor cells in culture and has been designated as I(0) based on its elution characteristics in gel filtration chromatography. This molecule cannot be found in a variety of nonneuronal cells. I(0) is found in the substratum-attached material or cell fraction of neurite-producing neuroblastoma cells, depending upon culture conditions. It is found in the substratum-bound fraction of B104 rat neuroblastoma cells during serum starvation and in the EGTA-detached cell fraction of B104 cells grown in chemically defined N2 medium. It occurs only in the cell fraction of the human neuroblastoma line Platt. Examination of behavioral variants of the B104 rat line further strengthens the association of I(0) with neurite production; the constitutive neurite-producing E(R)B9 variant contains I(0) while the non-neurite-producing E(R)A11 variant does not. I(0) is large, eluting in the void volume of sepharose-CL2B columns. Radioiodination of intact cells with lactoperoxidase shows I(0) to be a cell surface component. Metabolic radiolabeling studies show that it contains a high proportion of polysaccharide to protein, does not contain mannose, and is unsulfated. Alkaline borohydride reduction release two size classes of large polysaccharide chain. The alkaline reduction results, along with the mannose incorporation studies, show the presence of O-glycosidic linkages and few, if any, N-linkages. Resistance to nitrous acid deamination, insensitivity to glycosaminoglycan lyases, and the absence of sulfation, indicate that I(0) does not contain the glycosaminoglycans hyaluronic acid, chondroitin-, dermatan-, or heparin- sulfates. Affinity column chromatography reveals high binding affinity of I(0) to polyornithine and no binding to gelatin (collagen) or the glycosaminoglycans hyaluronate and heparin. These studies describe a unique high molecular weight glycoconjugate on the surface of neurite-producing neuroblastoma cell lines from two species.     

Electron paramagnetic resonance studies on the high-salt form of bovine spleen purple acid phosphatase.

The EPR spectra of the high-salt form of reduced bovine spleen purple acid phosphatase (BSPAPr) and its complexes with inhibitory tetrahedral oxyanions, AMP, and fluorine have been examined in the 4-30 K temperature range. The EPR spectrum of the high-salt form of BAPAPr is identical to that previously reported for the low-salt form (Averill et al. (1987) J. Am. Chem. Soc. 109, 3760-3767), indicating that the substantial differences in conformation of the two forms result in undetectable alterations in the electronic structure of the binuclear iron center. Phosphate, AMP, and arsenate all result in broadened, highly anisotropic EPR spectra with decreased values of the antiferromagnetic coupling constant, -2J, while molybdate and tungstate produce a sharp axial or slightly rhombic spectrum, respectively, and fluoride produces an anomalous spectrum with an inverted g-tensor. These results are consistent with binding of the two classes of oxyanions (and AMP) to distinct sites at or near the binuclear iron center, while fluoride binds in yet a third mode. EPR spectra of the BSPAPr complex with molybdate show altered relaxation behavior in the presence of phosphate, consistent with a 50% decrease in the magnitude of -2J, suggesting that phosphate binds to the molybdate complex to produce a ternary complex analogous to that proposed for molybdate inhibition on the basis of kinetics studies.     

Deep-level diagnostic value of the rDNA-ITS region

The similarity of certain reported angiosperm rDNA internal transcribed spacer (ITS) region sequences to those of green algae prompted our analysis of the deep-level phylogenetic signal in the highly conserved but short 5.8S and hypervariable ITS2 sequences. We found that 5.8S sequences yield phylogenetic trees similar to but less well supported than those generated by a ca. 10-fold longer alignment from rDNA-18S sequences, as well as independent evidence. We attribute this result to our finding that, compared to 18S, the 5.8S has a higher proportion of sites subject to vary and greater among-site substitution rate homogeneity. We also determined that our phylogenetic results are not likely affected by intramolecular compensatory mutation to maintain RNA secondary structure nor by evident systematic biases in base composition. Despite historical homology, there appears to be no ITS2 primary sequence similarity shared sufficient similarity to cluster correctly on the basis of alignability. Our results indicate that groups, however, share sufficient similarity to cluster correctly on the basis of alignability. Our results indicate that ITS region sequences can diagnose organismal origins and phylogenetic relationships at many phylogenetic levels and provide a useful paradigm for molecular evolutionary study.      

Production of Serine Proteases by the Oyster Pathogen Perkinsus marinus (Apicomplexa) In Vitro

ABSTRACT. Analysis of the cell-free supernatants of Perkinsus marinus cultures by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining revealed the presence of as many as 17 bands ranging in molecular weight from 239 to 32 kDa. These bands were not present in un-inoculated medium. Moreover, P. marinus produces extracellular proteins that possess proteolytic activities; the cell-free supernatants of P. marinus cultures could digest a variety of proteins including gelatin, casein, fibronectin and laminin. Oyster plasma was also digested by cell-free culture supernatants. The proteolytic activity in cell-free culture supernatants was detected 24 h post-inoculation, while no proteolytic activity could be detected in cell lysates. The proteolytic activities were characterized using substrate-impregnated sodium dodecylsulfate-polyacrylamide gels and had approximate molecular weights ranging from 55 to 35 kDa. The proteolytic activity of cell-free culture supernatants was inhibited by the serine protease inhibitors phenylmethylsulphonyl fluoride, 3,4-dichloroisocoumarin and soybean trypsin inhibitor. In contrast, inhibitors (i.e. trans-epoxysuccinyll-leucylamido(4-guanidino)-butane, 1, 10-phenanthroline, captopril, ethylenediaminetetracetic acid, pepstatin A or diazoacetyl-DL-norleucine methyl ester) from the other three classes of proteases had no effect. It was concluded that the P. marinus proteases in cell-free culture supernatants are serine proteases.