Cervical screening in Luxembourg: 1990–1999

For quality assurance purposes, the results of the 1990's obtained by the National Cervical Cancer Screening Programme (NCCSP) launched in 1962 were reviewed. The positive cytodiagnosis, the histologically verified in situ and invasive cervical cancers and the mortality rates were reported.     

Values of growth fraction and cell loss factor of sixty-five tumours re-examined

It has been shown that the mathematical evaluation of data from many cell kinetic experiments, published up to 1977, was rather inaccurate. The discrepancies between published values of growth fraction (GF) and the cell loss factor phi, and the results of new calculations based on the same values of LI, Td, TC, TG1, TS and TG2, are sometimes surprising. Using a suitable approximation of ex-1, the known formulae for GF and phi are replaced by simpler ones of sufficient accuracy. This may help to avoid computational errors in future cell kinetic studies of tumours.     

Host density and the evolution of parasite virulence

Social and cultural habits of human populations affect the biological evolution of the agents of infectious diseases. Measles and similar diseases have evolved in the Old World and cannot have existed in their present form before the rise of the great river valley civilizations. It is suggested that increased virulence of measles in white and indigenous communities in America 1500-1800 may be due to a rare strain of the virus, which was selected during transfer from Europe. The release of viruses for biological pest control has provided new material for the study of the co-evolution of host-parasite systems, which has upset the dogma "evolution tends to avirulence". It is pointed out that this issue is closely related to the group selection debate among ethologists, i.e. to the problem: how can group selection overcome individual selection? A model is proposed in which differential growth of two strains of a parasite within the host and their transmission to new hosts is considered. It is supposed that transmission stages excreted by infectious hosts enter a common pool where they are mixed before infecting new hosts. Under these conditions, selection of the slower strain is possible only if the mean size of parasite inoculum is very small, i.e. if the density of transmission stages in the environment is low. The impact of this result on host pathology depends on the relation between virulence and transmission efficiency of the parasite.     

Comparative effects of trichothecene mycotoxins on bovine platelet function: Acetyl T-2 toxin,a more potent inhibitor than T-2 toxin

The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10^?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds.     

吐鲁番市胃食管反流病发生相关危险因素分析（附280例报道）

目的：探讨280例胃食管反流病（GERD）的分布特点及危险因素。方法：对临床诊断和胃镜确诊的280例GERD患者进行临床和风险因子相关性分析。结果：不论汉族还是维族,男性患者比例均明显高于女性;汉族患者高发年龄段早于维族患者（z=-2．939,P=0．003,）;汉族和维族患者占反流性食管炎和Barrett食管比例分别为42．4％、81_3％及56．5％、18．8％,其中汉族患者Barrett食管比例较高（X2=14．358,P=0．000）;肥胖、习惯性便秘、重体力活动者、饮食习惯不良在维族患者中的比例较高（P〈0．001）。结论：GERD与性别、年龄密切相关,男性多于女性,汉族患者发病年龄高峰旱于维族患者;汉族患者Barrett食管发生比例高于维族患者;肥胖、习惯性便秘、重体力活动、饮食习惯不良可能是GERD尤其是维族人群GERD的危险因素。     

Successful immunotherapy with matrix metalloproteinase-derived peptides in adjuvant arthritis depends on the timing of peptide administration

We have recently found that matrix metalloproteinases (MMPs) are targets for T-cell and B-cell reactivity in experimental arthritis. In the present article, we investigate whether modulation of MMP-specific T-cell responses could influence the course of adjuvant arthritis (AA). Lewis rats were treated nasally with MMP peptides prior to or after AA induction. Administration of the MMP-10 or the MMP-16 peptide prior to AA induction reduced the arthritic symptoms. In contrast, administration of the MMP-10 peptide after AA induction aggravated the arthritic symptoms. The present study shows the possible usefulness of MMP peptides for immunotherapy. However, a clear understanding of proper timing of peptide administration is crucial for the development of such therapies.     

DUG is a novel homologue of translation initiation factor 4G that binds eIF4A

To elucidate the molecular mechanisms of cell death, we have cloned a new gene, designated death-upregulated gene (DUG), from rat insulinoma cells. DUG is constitutively expressed at very low levels in normal cells but is dramatically upregulated in apoptotic cells following serum/glucose starvation or death receptor ligation by Fas ligand. The DUG mRNA is present in two splicing forms: a long form that encodes a protein of 469 amino acids and a short form that gives rise to a polypeptide of 432 amino acids. The predicted DUG protein sequence contains two putative nuclear localization signals and multiple phosphorylation sites for protein kinases and two conserved MA3 domains. Importantly, DUG is homologous to eukaryotic translation initiation factor (eIF) 4G and binds to eIF4A presumably through MA3 domains. Upon transfection, DUG inhibits both intrinsic and extrinsic pathways of apoptosis. Thus, DUG is a novel homologue of eIF4G that regulates apoptosis.     

Characterization of terminal NeuNAcalpha2-3Galbeta1-4GlcNAc sequence in lipooligosaccharides of Neisseria meningitidis

Group B and C Neisseria meningitidis are the major cause of meningococcal disease in the United States and in Europe. N . meningitidis lipooligosaccharide (LOS), a major surface antigen, can be divided into 12 immunotypes of which L1 through L8 were found among Group B and C organisms. Groups B and C but not Group A may sialylate their LOSs with N-acetylneuraminic acid (NeuNAc) at the nonreducing end because they synthesize CMP-NeuNAc. Using sialic acid-galactose binding lectins as probes in an ELISA format, six of the eight LOS immunotypes (L2, L3, L4, L5, L7, and L8) in Groups B and C bound specifically to Maackia amurensis leukoagglutinin (MAL), which recognizes NeuNAcalpha2- 3Galbeta1-4GlcNAc/Glc sequence, but not to Sambucus nigra agglutinin, which binds NeuNAcalpha2-6Gal sequence. The combination of SDS-PAGE and MAL-blot analyses revealed that these six LOSs contained only the NeuNAcalpha2-3Galbeta1-4GlcNAc trisaccharide sequence in their 4.1 kDa LOS components, which have a common terminal lacto-N-neotetraose (LNnT, Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc) structure when nonsialylated as shown by previous studies. The LOS-lectin binding was abolished when the LOSs were treated with Newcastle disease viral neuraminidase which cleaves alpha2-->3 linked sialic acid. Methylation analysis of a representative LOS (L2) confirmed that NeuNAc is 2-->3 linked to Gal. Thus, these LOSs structurally mimic certain glycolipids, i.e., paragloboside (LNnT-ceramide) and sialylparagloboside and some glycoproteins in having LNnT and N-acetyllactosamine sequences, respectively, with or without alpha2-->3 linked NeuNAc. The molecular mimicry of the LOSs may play a role in the pathogenesis of N.meningitidis by assisting the organism to evade host immune defenses in man.