Classical Noonan syndrome is not associated with deletions of 22q11

Deletions of 22qll cause DiGeorge sequence (DGS), velo-cardio-facial syndrome (VCFS), conotruncal anomaly face syndrome, and some isolated conotruncal heart anomalies. Demonstration of a 22qll deletion in a patient with manifestations of DGS and Noonan syndrome (NS) has raised the question of whether NS is another of the chromosome 22 microdeletion syndromes. This prompted us to evaluate a cohort of patients with NS for evidence of 22qll deletions. Five of 6 NS propositi studied in our laboratory with marker N25 (D22S75) did not have a 22qll deletion. A 2-month-old infant with several findings suggestive of NS did have a 22qll deletion, suggesting that a small number of 22qll deletion propositi may present with a NS-like picture. However, most cases of NS must have another cause. © 1995 Wiley-Liss, Inc.     

Progress in the autosomal segmental aneusomy syndromes (SASs): single or multi-locus disorders?

Based on cytogenetic observations, several syndromes have been previously identified as microdeletion-based disorders. In this review, recent progress is presented regarding whether one or multiple genes can be implicated in the pathogenesis of these segmentally aneusomic syndromes. The syndromes discussed include Angelman, Alagille, Williams, Langer-Giedeon, Prader-Willi, Smith-Magenis, Miller-Dieker, and DiGeorge/velocardiofacial or the 22q11 deletion syndromes. For Angelman and Alagille syndromes, single genes have been identified, whereas for Williams and Langer-Giedion syndromes, more than one gene can be implicated. Although there has been significant progress in dissecting the molecular basis for the other disorders, the ultimate answer regarding one versus several genes remains to be determined.      

Clonal aberrations of chromosomes X, Y, 7 and 10 in normal kidney tissue of patients with renal cell tumors.

By means of G-banding techniques, chromosome aberrations were studied in short-term cultures of normal renal parenchymal cells from 45 patients with renal cell carcinoma. Clonal chromosomal aberrations were detected in 29 patients; loss of the Y chromosome as well as trisomy X, 5, 7, 9, 10, 12, and 18 was found. Chromosomes 7 and 10 were involved preferentially. Results of fluorescence in situ hybridization with chromosome 7- and 10-specific DNA probes on non-cultured normal kidney cells suggested that the aberrations developed in vivo.     

Release of a potent polymorphonuclear leukocyte chemoattractant is regulated by white-opaque switching in Candida albicans

Previous studies employing transmembrane assays suggested that Candida albicans and related species, as well as Saccharomyces cerevisiae, release chemoattractants for human polymorphonuclear leukocytes (PMNs). Because transmembrane assays do not definitively distinguish between chemokinesis and chemotaxis, single-cell chemotaxis assays were used to confirm these findings and test whether mating-type or white-opaque switching affects the release of attractant. Our results demonstrate that C. albicans, C. dubliniensis, C. tropicalis, C. parapsilosis, and C. glabrata release bona fide chemoattractants for PMNs. S. cerevisiae, however, releases a chemokinetic factor but not a chemoattractant. Characterization of the C. albicans chemoattractant revealed that it is a peptide of approximately 1 kDa. Whereas the mating type of C. albicans did not affect the release of chemoattractant, switching did. White-phase cells released chemoattractant, but opaque-phase cells did not. Since the opaque phase of C. albicans represents the mating-competent phenotype, it may be that opaque-phase cells selectively suppress the release of chemoattractant to facilitate mating.     

Biochemical assessment and clinical evaluation of a bilirubin adsorbent column (BR-350) in critically ill patients with intractable jaundice.

We investigated the efficacy of an anion-exchange adsorbent column (ASAHI BR-350, DIAMED) for removal of bilirubin and bile acids in five patients with intractable jaundice of various origin. Four litres of plasma were separated by membrane plasma separation (Plasmaflow OP-05) at a rate of 22.5 ml/min. The plasma was then perfused through an anion exchange adsorbent and returned to the venous blood line of the plasma separation. In some of the patients this procedure was combined with regular hemodialysis treatment. The concentration of total bilirubin was cut by 31 to 60%; total bile acids were reduced by 20 to 74%. Three patients recovered and had a favourable outcome. Two patients died despite the bilirubin adsorption treatment. The effects of the adsorbent column on specific blood parameters, including the coagulation system, were measured. Our data suggest that bilirubin adsorption should be examined further as a treatment for critically ill patients with intractable jaundice.     

Group‐specific component (GC) in curiaú and pacoval,two african‐derived brazilian populations

The group‐specific component (GC) system is of interest in anthropological genetic studies because the distribution of its subtypes distinguishes among major ethnic groups. The GC system was analyzed in Curiaú and Pacoval, two remnant Quilombo populations (African‐derived populations) from the Brazilian Amazon. There was no significant statistical difference in allelic frequencies between the two populations or between them and three other African‐derived Brazilian populations (Mimbó, Sítio Velho, and Gaucinha in Northeastern Brazil). These populations share similarities among themselves and with African populations (high frequencies of GC*1F and lower frequencies of GC*1S), which may reflect the influence of a high level of African contribution to their formation, but there is a clear difference between them and Europeans and South American Indians. It is suggested that the GC system is a useful marker for studying relationships between single populations and major ethnic groups, but does not discriminate between populations which share the same parental stock. Am. J. Hum. Biol. 13:718–720, 2001. © 2001 Wiley‐Liss, Inc.     

Lysogeny and lysosensitivity inShigella dysenteriae Group of bacteria

Shigella dysenteriae 7 (D7) strain was extracted by using the Westphal water/phenol method and the extract obtained (Aq/Ph 68?C) was found to have the receptor activity against both T2 and T4 phages. It was shown by the receptor neutralization test that the examined substance had receptor sites distinctive for T2 and T4 phages. The receptor sites for phage T2 had common antigen specificity with receptor sites of this phage localized inE. coli B in the lipoprotein fraction; the receptor sites of phage T4 had common antigen specificity with receptor sites to phage T4, localized inE. coli B in Aq/Ph 68? C extract. It is suggested that in spite of the different localization, the receptors for the same phage in the different bacterial species examined have common serological specificity.     

Presynaptic short-term depression is maintained during regulation of transmitter release at a GABAergic synapse in rat hippocampus

To examine possible interactions between fast depression and modulation of inhibitory synaptic transmission in the hippocampus, we recorded from pairs of synaptically connected basket cells (BCs) and granule cells (GCs) in the dentate gyrus of rat brain slices at 34 °C. Multiple-pulse depression (MPD) was examined in trains of 5 or 10 inhibitory postsynaptic currents (IPSCs) evoked at frequencies of 10–00 Hz under several conditions that inhibit transmitter release: block of voltage-dependent Ca²⁺ channels by Cd²⁺ (10 μ m ), activation of γ-amino-butyric acid type B receptors (GABA_BRs) by baclofen (10 μ m ) and activation of muscarinic acetylcholine receptors (mAchRs) by carbachol (2 μ m ). All manipulations led to a substantial inhibition of synaptic transmission, reducing the amplitude of the first IPSC in the train (IPSC₁) by 72 %, 61 % and 29 %, respectively. However, MPD was largely preserved under these conditions (0.34 in control versus 0.31, 0.50 and 0.47 in the respective conditions at 50 Hz). Similarly, a theta burst stimulation (TBS) protocol reduced IPSC₁ by 54 %, but left MPD unchanged (0.40 in control and 0.39 during TBS). Analysis of both fractions of transmission failures and coefficients of variation (CV) of IPSC peak amplitudes suggested that MPD had a presynaptic expression site, independent of release probability. In conclusion, different types of presynaptic modulation of inhibitory synaptic transmission converge on a reduction of synaptic strength, while short-term dynamics are largely unchanged.