Escherichia coli Heat-Labile Enterotoxin Binds to Glycosylated Proteins with Lactose by Amino Carbonyl Reaction

The binding of Escherichia coli heat-labile enterotoxin (LT) type I to glycosylated proteins with lactose (Galβ1-4Glc) by amino carbonyl reaction was studied by the Western blot assay and by the microtiter well binding assay. LT bound to a lactose-α-lactalbumin amino carbonyl product (Lac-LA), whereas cholera toxin did not. The binding ability of Lac-LA was abolished by β-galactosidase treatment, indicating that the terminal galactose is essential for the binding of LT. The binding of LT to Lac-LA was inhibited by galactose and lactose, and most effectively inhibited by lactulose (Galβ1-4Fru), which is a structural analog of the Amadori rearrangement product of the amino carbonyl reaction between lactose and an ε-amino group of a lysine residue (lactuloselysine). The results suggest that LT recognizes the portion of lactuloselysine in Lac-LA. LT also bound to a melibiose (Galα1-6Glc)-α-lactalbumin amino carbonyl product (Mel-LA), but the binding ability of Mel-LA was weaker than that of Lac-LA, suggesting that the β1-4 linked terminal galactose is dispensable but preferable for the binding. Furthermore, LT bound to the amino carbonyl products of lactose with β-lactoglobulin, caseins, bovine serum albumin, and ovalbumin. These results indicate that LT binds to the amino carbonyl products between proteins and sugars containing the terminal galactose, such as lactose.     

Retroviral Oligonucleotide Distributions Correlate with Biased Nucleotide Compositions of Retrovirus Sequences,Suggesting a Duplicative Stepwise Molecular Evolution

A computer-assisted analysis was made of 24 complete nucleotide sequences selected from the vertebrate retroviruses to represent the ten viral groups. The conclusions of this analysis extend and strengthen the previously made hypothesis on the Moloney murine leukemia virus: The evolution of the nucleotide sequence appears to have occurred mainly through at least three overlapping levels of duplication: (1) The distributions of overrepresented (3–6)-mers are consistent with the universal rule of a trend toward TG/CT excess and with the persistence of a certain degree of symmetry between the two strands of DNA. This suggests one or several original tandemly repeated sequences and some inverted duplications. (2) The existence of two general core consensuses at the level of these (3–6)-mers supports the hypothesis of a common evolutionary origin of vertebrate retroviruses. Consensuses more specific to certain sequences are compatible with phylogenetic trees established independently. The consensuses could correspond to intermediary evolutionary stages. (3) Most of the (3–6)-mers with a significantly higher than average frequency appear to be internally repeated (with monomeric or oligomeric internal iterations) and seem to be at least partly the cause of the bias observed by other researchers at the level of retroviral nucleotide composition. They suggest a third evolutionary stage by slippage-like stepwise local duplications. Received: 3 January 1996 / Accepted: 27 March 1996     

Effects of forskolin and cholera toxin on cyclic AMP release in a neurotensin-secreting rat C-cell line

The effects of forskolin and cholera toxin on the regulation of cAMP release were studied in a neurotensin-secreting rat C-cell line. The interaction of these agents with norepinephrine, a potent neurotensin secretagogue, was also investigated. Forskolin stimulated cAMP release 10(2)-10(3) fold while it increased neurotensin release 2-3 fold. Cholera toxin caused a 10(2)-10(3) fold increase in cAMP release and had no effect on neurotensin release. We conclude that the 44-2 C-cells provide a new model for studying the regulation of the concomitant (via forskolin) or independent (via cholera toxin) secretion of cyclic AMP and/or neurotensin.     

Proteolytic fragmentation of myosin: location of SH-1 and SH-2 thiols.

The heavy chain fragmentation pattern of native myosin when digested by proteolytic enzymes is influenced by such conditions as the nature of the proteolytic agent, ionic strength and presence or absence of divalent cations. HMM and S-1 produced by digestion of 14CNEM-labelled myosin under various conditions were analyzed by sodium dodecyl-sulfate polyacrylamide gel electrophoresis. Purified samples of these species were digested under controlled conditions by chymotrypsin and trypsin and a comparison of the observed heavy chain fragmentation patterns led to a sequential arrangement of the proteolytic fragments. The main features of this arrangement are the following: a 21K molecular weight tryptic peptide is found at the N-terminal side of myosin heavy chain. Adjacent to it is a 48K peptide, then a 19.5K peptide containing the two SH-1 and SH-2 thiols. These three peptides constitute the heavy chain of S-1. Adjacent to this S-1 heavy chain is a tryptic (and also chymotryptic) 40K peptide. The rest of the HMM heavy chain on the C-terminus is a sequence susceptible to both chymotrypsin and trypsin attack yielding an undefined number of small peptides.     

Atmin modulates Pkhd1 expression and may mediate Autosomal Recessive Polycystic Kidney Disease (ARPKD) through altered non-canonical Wnt/Planar Cell Polarity (PCP) signalling

Autosomal Recessive Polycystic Kidney Disease (ARPKD) is a genetic disorder with an incidence of ~1:20,000 that manifests in a wide range of renal and liver disease severity in human patients and can lead to perinatal mortality. ARPKD is caused by mutations in PKHD1, which encodes the large membrane protein, Fibrocystin, required for normal branching morphogenesis of the ureteric bud during embryonic renal development. The variation in ARPKD phenotype suggests that in addition to PKHD1 mutations, other genes may play a role, acting as modifiers of disease severity. One such pathway involves non-canonical Wnt/Planar Cell Polarity (PCP) signalling that has been associated with other cystic kidney diseases, but has not been investigated in ARPKD. Analysis of the Atmin^Gpg6 mouse showed kidney, liver and lung abnormalities, suggesting it as a novel mouse tool for the study of ARPKD. Further, modulation of Atmin affected Pkhd1 mRNA levels, altered non-canonical Wnt/PCP signalling and impacted cellular proliferation and adhesion, although Atmin does not bind directly to the C-terminus of Fibrocystin. Differences in ATMIN and VANGL2 expression were observed between normal human paediatric kidneys and age-matched ARPKD kidneys. Significant increases in ATMIN, WNT5A, VANGL2 and SCRIBBLE were seen in human ARPKD versus normal kidneys; no substantial differences were seen in DAAM2 or NPHP2. A striking increase in E-cadherin was also detected in ARPKD kidneys. This work indicates a novel role for non-canonical Wnt/PCP signalling in ARPKD and suggests ATMIN as a modulator of PKHD1.     

两种碘浓度对比剂对肾脏CT增强扫描的对比研究

目的：对比300 mgI.ml-1对比剂与400 mgI.ml-1对比剂对肾脏多层面CT（multislice CT,MSCT）多期增强扫描的强化作用及不良反应。材料与方法：68例腹部CT受检者随机分成两组各34例,分别给予肾脏平扫和典比乐300（300 mgI.ml-1）与碘迈伦400（400 mgI.ml-1）的多期增强MSCT扫描（在对比剂开始注射后18s、30 s、80 s、3 min~5 min）,测量各期增强扫描腹主动脉、双肾动脉、双肾静脉、双肾皮质、双肾髓质、双肾盂的CT强化值。观察对比剂的不良反应。结果：使用400 mgI.ml-1对比剂在18s与30s采集,所检测的血管与肾各结构强化均值有意义高于300 mgI.ml-1对比剂（p〈0.01）,80 s采集,肾动脉、肾静脉、肾髓质强化均值有意义高于300 mgI.ml-1对比剂（p〈0.01）,3 min~5 min采集,肾静脉与肾盂强化均值有意义高于300 mgI.ml-1对比剂（p〈0.01）。结论：高碘浓度对比剂对肾脏各解剖结构的显示优于标准碘浓度对比剂,并可降低对比剂用量,而不良反应并无增加。     

低剂量与常规剂量扫描在CT引导下经皮穿刺肺活检术中的临床应用价值对比研究

摘要 目的：比较低剂量与常规剂量扫描在CT引导下经皮穿刺肺活检术中的临床应用价值。方法：选择2018年1月至2019年12月我院行CT引导下经皮穿刺肺活检术的患者96例,采用随机数字表法分为低剂量组和常规剂量组,每组48例,两组分别在低剂量扫描、常规剂扫描下行CT引导下经皮穿刺肺活检术,比较两组扫描范围、X射线剂量、图像质量、穿刺成功率及并发症发生情况。结果：低剂量组CT吸收剂量加权指数（CTDIw）、平均剂量长度乘积（DLP）显著低于常规剂量组（P<0.05）,两组扫描范围比较无统计学差异（P>0.05）。低剂量组图像质量1级1例、2级1例、3级46例;常规剂量组1级0例、2级1例、3级47例,两组图像质量比较无统计学差异（P>0.05）。低剂量组穿刺成功率87.50%,常规剂量组穿刺成功率89.58%,两组穿刺成功率比较无统计学差异（P>0.05）。低剂量组并发症发生率为12.50%,常规剂量组并发症发生率为10.42%,两组并发症发生率比较差异无统计学意义（P>0.05）。结论：与常规剂量扫描相比,在CT引导下经皮穿刺肺活检术中应用低剂量扫描可以有效降低辐射剂量,但不影响图像质量和穿刺成功率,患者并发症发生率也未增加,具有较好的临床价值。     

A novel homozygous 10 nucleotide deletion in BBS10 causes Bardet–Biedl syndrome in a Pakistani family

Bardet–Biedl Syndrome is a multisystem autosomal recessive disorder characterized by central obesity, polydactyly, hypogonadism, learning difficulties, rod-cone dystrophy and renal dysplasia. Bardet–Biedl Syndrome has a prevalence rate ranging from 1 in 100,000 to 1 in 160,000 births although there are communities where Bardet–Biedl Syndrome is found at a higher frequency due to consanguinity. We report here a Pakistani consanguineous family with two affected sons with typical clinical features of Bardet–Biedl Syndrome, in addition to abnormal liver functioning and bilateral basal ganglia calcification, the latter feature being typical of Fahr's disease. Homozygous regions obtained from SNP array depicted three known genes BBS10, BBS14 and BBS2. Bidirectional sequencing of all coding exons by traditional sequencing of all these three genes showed a homozygous deletion of 10 nucleotides (c.1958_1967del), in BBS10 in both affected brothers. The segregation analysis revealed that the parents, paternal grandfather, maternal grandmother and an unaffected sister were heterozygous for the deletion. Such a large deletion in BBS10 has not been reported previously in any population and is likely to be contributing to the phenotype of Bardet–Biedl Syndrome in this family.     

CT诊断用于胰腺癌侵犯胰周动静脉的临床价值分析

目的：探究CT诊断对于胰腺癌侵犯胰周动静脉的临床价值。方法：随机选取在我院就诊的64例胰腺癌患者,在他们进行手术前全在距离肿瘤边缘1cm内的血管进行分期和诊断进而进行螺旋CT检查。结果：经组织学术后病理切片染色发现胰周动脉29条,静脉48条。运用外科手术探查方法发现86条胰周动脉,89条胰周静脉。在这些血管中,有23条动脉、47条静脉经外科手术证实的确是肿瘤侵犯,并且经过CT诊断,我们最终断定为有25条动脉、46条静脉处于1～4级。结论：胰周动、静脉受到侵犯时,具有不同的CT表现特征,因此在利用CT方法判断胰周动、静脉遭受侵犯时应当根据不同情况不同对待。