De novo 13q partial duplication identified by cytogenetic, biochemical and molecular approaches

A 3.5-month-old female infant manifesting dysmorphic facies, developmental delay and failure to thrive was referred for cytogenetic evaluation. Peripheral lymphocytes revealed three chromosomally distinct cell lines: 46,XX/46,XX,10p+/47,XX,10p+,+mar. Dermal fibroblasts revealed only the 46,XX,10p+cell line. High resolution G-, R-, and Q-banding suggested that the extra chromosomal material (10p+) represented a duplication of the segment 13q14----13qter. Parental karyotypes were normal. As absolute identification of de novo chromosomal abnormalities, based solely on cytogenetic studies, is sometimes difficult, both biochemical and molecular approaches were undertaken to elucidate this abnormality in more detail. Dosage effects were examined using esterase D (localized to 13q14.1) and the DNA probes p1E8 and p9A7 (localized to 13q22 and 13q31/32, respectively). These studies suggested the presence of only 2 copies of esterase D, but 3 copies of both DNA probes, allowing identification of the breakpoint at 13q14.2.     

Age-related changes in gene expression patterns of matrix metalloproteinases and their collagenous substrates in mandibular condylar cartilage in rats

Matrix metalloproteinases (MMPs) have been implicated in physiological cartilage matrix remodelling as well as in pathological and invasive extracellular matrix remodelling of tissue. Age-related changes in the gene expression patterns of MMPs in mandibular condylar cartilages (MCCs) were analysed. We examined the gene expression patterns of Mmp-8 and -13 and their substrates, Col1a1, Col2a1 and Col10a1, in MCC of growing and ageing rats. Temporomandibular joints of male Wistar rats aged 4, 8, 16 and 32 weeks were subjected to in situ hybridization analysis. Histologically, MMCs showed characteristics of growth plate cartilage at ages 4 and 8 weeks, and more closely resembled articular cartilage thereafter. Mmp-8 was expressed in the cells in all cartilaginous cell layers at ages 4 and 8 weeks, and then was localized only in the mature cells at ages 16 and 32 weeks. Whereas Mmp-13 expression was limited to the lowermost hypertrophic chondrocytes in the growth stage, mature chondrocytes instead of hypertrophic chondrocytes expressed Mmp-13 in adult non-hypertrophic MCC. Because Mmp-8 and -13 expression overlapped with Col2a1 and Col10a1, chondrocytes could play a pivotal role in degradation as well as production of the cartilaginous matrix in MCC.     

PMX2B,a new candidate gene for Hirschsprung's disease

Hirschsprung's (HSCR) disease is a congenital intestinal malformation of the enteric nervous system. It is a multigenic malformation and until now, eight genes have been involved in the etiology of this disease: genes encoding proteins of the RET signaling pathway (RET, GDNF and NTN), genes participating in the endothelin (EDN) type B receptor pathway (EDNRB, EDN3 and ECE-1), the SOX10 gene and the SIP1 gene that is mutated in syndromic forms of HSCR. Mutations of these genes are found in not more than 50-60% of affected individuals. Here, we report on the results of a molecular cytogenetic study performed in a girl who presented with a syndromic short segment HSCR associated with a de novo t(4;8)(p13;p22) translocation. A comparative genomic hybridization (CGH) study found a 4p12p13 deletion. A molecular characterization of this rearrangement showed that the 4p13 deletion was 5 Mb in length and included the paired mesoderm homeobox gene (PMX2B) (MIM 603851), a gene expressed in the human embryonic gut and essential for the development of autonomic neural crest derivatives. The present observation suggests that PMX2B haploinsuffciency might predispose to HSCR.     

Different spinal effects of opioid agonists on spinal and spino-bulbo-spinal reflexes in rats

Summary The effects of morphine-HCl (MOR), methionine-enkephalin (ME) and dynorphin_1–13 (DYN) on spinal and spino-bulbo-spinal (SBS) reflexes were studied. Although spinal intrathecal administration of MOR (15g) did not produce any apparent effect on these reflexes, systemically administered MOR (3mg/kg i.v.) reduced the electrical toe stimulation-induced SBS reflex. Furthermore, MOR (3mg/kg i.v.) increased the polysynaptic reflex induced by electrical stimulation of low-threshold dorsal root afferents in intact (non-spinal) rats, but not in spinal rats. Intrathecally administred DYN (0.5 and 5 g) reduced both the electrical toe stimulation-induced spinal and SBS reflexes, while ME (15g) only reduced the SBS reflex. These results indicate the physiological multiplicity of spinal opioid receptors. MOR may affect supraspinal nuclei but not the spinal pathway which possesses MOR-sensitive opioid receptors, whereas ME and DYN affect spinal opioid peptide receptors and modulate the reflex activities in which they participate.     

Chromosome 11q13 markers and D-type cyclins in breast cancer

Summary One in six primary human breast cancers has DNA amplification centered on the cyclin D1 gene (CCND1) on chromosome 11q13. This genetic abnormality is preferentially associated with estrogen-receptor positive tumors and may define a sub-class of patients with an adverse prognosis. AlthoughCCND1 has the credentials of a cellular oncogene, being a target for chromosomal translocation and retroviral integration, the 11q13 amplicon encompasses several other markers andCCND1 is not the only candidate for the key gene on the amplified DNA. To assess their relative importance, we have constructed a physical map of the amplified DNA and compared the extent and frequency of amplification across the region. Since it is likely that the gene providing the selective force for amplification will be expressed at elevated levels, we have also examined expression of both RNA and protein. By these criteria, cyclin D1 remains the strongest candidate for the key oncogene on the amplicon and we are currently investigating the functional consequences of its over-expression.Presented by Gordon Peters at the 16th Annual San Antonio Breast Cancer Symposium, San Antonio TX, USA, November 4, 1993; Minisymposium on Molecular Genetics in Breast Cancer.     

Haemodynamic response to graded exercise during chronic beta-adrenergic blockade with bunitrolol,an agent with intrinsic sympathomimetic activity

Summary The effect of chronic beta blockade on the haemodynamic response to graded exercise was studied in 18 hypertensive patients treated with bunitrolol, which has partial agonist activity. The patients first received a placebo for 5 to 12 days, then bunitrolol 30 mg daily for one week and subsequently the dose was doubled weekly as necessary upto 240 mg daily. At rest haemodynamic changes after beta blockade were only minor; heart rate decreased by 8% and no significant change was observed in stroke index, cardiac index, (a-v)O₂ difference and VO₂. The hypotensive effect was not significant and no significant change in mean pulmonary arterial and wedge pressure was observed. Maximal exercise capacity remained unchanged, because of haemodynamic responses. The maximal exercise heart rate was reduced by 25% during beta blockade, which was compensated by a 34% elevation in stroke index, whereas maximal cardiac index and (a-v)O₂ difference remained unchanged. There was no consistent change in mean pulmonary artery pressure during maximal exercise, but the mean brachial artery pressure fell by 12%.     

维甲酸诱导后CK13基因在鼻咽癌中的表达研究

目的探讨维甲酸(retinoic acids,RA)对鼻咽癌细胞株HNE1生长及表型的作用,同时观察维甲酸诱导鼻咽癌细胞株HNE1后细胞角蛋白基因13(cytokeratin 13,CK13)表达情况。方法应用细胞培养的方法观察维甲酸诱导鼻咽癌细胞株HNE1细胞的生长状况,利用Northern杂交技术分析维甲酸诱导鼻咽癌细胞株HNE1后CK13基因的表达。结果维甲酸能显著抑制鼻咽癌细胞的生长,抑制的强度取决于维甲酸的浓度和诱导持续时间,当维甲酸的浓度为1×10-4 M/L时,前4天下降约50％,第5天开始细胞停止增殖,细胞数逐渐减少,细胞逐渐老化死亡。维甲酸处理后的鼻咽癌细胞从典型的多边形变成扁平、细长,类似纤维细胞的形态。维甲酸诱导后的鼻咽癌细胞中CK13基因的表达明显上调,且与维甲酸的浓度有关。结论维甲酸能促进鼻咽癌细胞的分化,可能是通过上调CK13基因的表达而实现的。     

Synthesis and physico‐chemical properties of peptides in soil humic substances

Abstract: Soil humic substances (HS) are heterologous, polydispersive, and multi‐functional organometallic macromolecules ubiquitous in soils and sediments. They are key players in the maintenance of the belowground ecosystems and in the bioavailability of both organic and inorganic contaminants. It is widely assumed that the peptidic substructures of HS are readily degraded and therefore do not contribute significantly to interactions with contaminants such as toxic metals. To investigate the turnover of humified peptides, laboratory soil aging experiments were conducted with ¹³C‐glucose or ¹⁵N‐nitrate for 8.5 months. Evidence for random‐coil peptidic structures in the labeled HS was obtained from 2‐D nuclear magnetic resonance (NMR), pyrolysis gas chromatography‐mass spectrometry (pyro‐GC‐MS), and circular dichroism data. Interaction of metals with the peptidic carbonyls of labeled HS was rationalized from the solid‐state NMR data. Detailed ¹³C and ¹⁵N labeling patterns of amino acid residues in the acid hydrolysates of HS acquired from NMR and GC‐MS revealed two pools of peptides, i.e. one extant (unlabeled) and the other, newly humified with little isotopic scrambling (fully labeled). The persistence of pre‐existing peptidic structures indicates their resistance to degradation while the presence of fully labeled peptidic amino acids suggests wholesale incorporation of newly synthesized peptides into HS. These findings are contrary to the general notion that humified peptides are readily degraded.