生长抑素及其受体与肝癌

生长抑素(somatostatin,SS)是一种环状多肽类激素,在体内有两种形式,即SS-14和SS-28,均具有显著的生物学活性[1,2],它们对生长激素(GH)、胰岛素、促胃液素等多种内、外分泌激素具有强大的抑制作用,并参与调节大脑运动和识别功能[3].近年研究显示,SS具有抑制肿瘤细胞增殖、诱导肿瘤细胞凋亡功能,其生物学效应是通过靶细胞上特异性的生长抑素受体(human somatostatin receptor,hSSR)介导的[4,5].     

More to ADHD than meets the eye: Observable abnormalities in search behaviour do not account for performance deficits on a discrimination task

Children with Attention Deficit/Hyperactivity Disorder (ADHD) often perform poorly on tasks requiring sustained and systematic attention to stimuli for extended periods of time. The current paper tested the hypothesis that such deficits are the result of observable abnormalities in search behaviour (e.g., attention-onset, -duration and -sequencing), and therefore can be explained without reference to deficits in non-observable (i.e., cognitive) processes. Forty boys (20 ADHD and 20 controls) performed a computer-based complex discrimination task adapted from the Matching Familiar Figures Task with four different fixed search interval lengths (5-, 10-, 15- and 20-s). Children with ADHD identified fewer targets than controls (p < 0.001), initiated searches later, spent less time attending to stimuli, and searched in a less intensive and less systematic way (p's < 0.05). There were significant univariate associations between ADHD, task performance and search behaviour. However, there was no support for the hypothesis that abnormalities in search carried the effect of ADHD on performance. The pattern of results in fact suggested that abnormal attending during testing is a statistical marker, rather than a mediator, of ADHD performance deficits. The results confirm the importance of examining covert processes, as well as behavioural abnormalities when trying to understand the psychopathophyiology of ADHD.     

Follow up of infection of chacma baboons with inoculum containing A and non-A genotypes of hepatitis B virus

AIM: To determine whether one genotype (A or non-A genotypes of HBV) predominated over the other during the course of HBV infection. METHODS: Four baboons were inoculated with HBV. DNA was extracted from serum obtained at monthly intervals post-inoculation for 52 weeks and HBV DNA was amplified using primers specific for the core region containing an insert characteristic of genotype A (nt 2 354-2 359, numbering from the EcoRI site). The amplicons were cloned into PCR-Script(TM) and a minimum of 15 clones per time point were sequenced in both directions. RESULTS: Both genotypes persisted for the entire follow-up period of 52 weeks. Genotype non-A predominated in two baboons and genotype A in one baboon. Neither genotype predominated in the fourth baboon, as shown at a 5 % level of testing. CONCLUSION: No conclusions concerning the dominance of either genotype or the natural progression or replication rates of HBV could be drawn because the pattern of the genotypes found may have been caused by sampling fluctuations at the time of DNA extraction and cloning as a result of the very low viral loads in the baboon sera.     

Bilateral calcaneal fractures: operative versus nonoperative treatment

BACKGROUND: There is poor information in the literature regarding patients who suffer from bilateral calcaneal fractures. The objective of this study was to analyze demographic characteristics and objective clinical features of patients with bilateral calcaneal fractures as well as subjective outcomes following either operative or conservative management. It was a prospective randomized trial. It was performed at four level 1 trauma centers. METHODS: Forty-seven patients sustaining bilateral calcaneal fractures were randomized to either operative (open reduction and internal fixation) or conservative treatment groups. Demographic features and fracture patterns were compared between those sustaining unilateral fractures (large calcaneal database) and those sustaining bilateral fractures. Following treatment, comparison of both objective outcome measures (Bohler's angle and subtalar range of motion) and subjective outcomes, as measured by the previously validated visual analogue scale (VAS) and SF-36 scores, was performed. Outcomes were also compared (with existing data from trauma database) for those treated for unilateral calcaneal fracture. RESULTS: No difference in demographic features was found between individuals suffering unilateral and bilateral calcaneal fractures. Among bilaterally injured patients, initial Bohler's angle was slightly, but significantly, more depressed relative to that in the unilateral comparison data (p <.05). Post-treatment range of motion was significantly better when injury was confined to one side regardless of treatment modality (p <.01). Surgical intervention did not significantly affect subjective patient outcome as measured by either SF-36 or the VAS. This remained true following stratification by Worker's Compensation Board (WCB) status. However, those who were treated nonoperatively were significantly more likely to require late subtalar arthrodesis (p <.05). In general, patients whose injury was not associated with a WCB claim demonstrated significantly better subjective outcomes (p <.01 for SF-36 and VAS). CONCLUSIONS: Other than demonstrating a slightly more depressed Bohler's angle, patients sustaining bilateral calcaneal fractures are very similar to those in whom the injury is confined to one side. The evidence presented here does not definitively support primary operative intervention for bilateral calcaneal fractures. Neither objective nor subjective functional outcomes are significantly improved following such intervention. However, careful operative patient selection will minimize complications and lessen the need for late subtalar arthrodesis.     

Repression of c-myc gene expression by the thiol and disulfide forms of the cytoprotector amifostine

The clinically approved cytoprotector amifostine, designated WR-2721, [S-2-(3-aminopropylamino)ethylphosphorothioic acid], protects against both radiation and drug-induced mutagenesis in animal systems. These effects extend over a wide concentration range making amifostine a strong candidate for evaluation as a possible cancer chemopreventive agent. To better identify and develop potential intermediate biomarkers for chemoprevention at the molecular level we applied the technique of differential display RT-PCR to assess the effects of both the thiol (SH), i.e. WR1065 and the disulfide (SS), i.e. WR-33278, metabolites of amifostine on gene expression in CHO-AA8 cells. Cells were exposed to either 40 microM or 4 mM of each agent for 30 min, and subsequent changes in gene expression were identified and contrasted to that found in corresponding untreated control cells. One band that showed a differential response was sequenced and was found to have 78% homology with a segment of the human pHL-1 cDNA clone contained in GenBank. This clone contains a COX III mitochondrial DNA insert and two exons of human c-myc. Northern blot analyses were performed by using the cloned human c-myc exon 1 probe to confirm whether c-myc gene expression was affected. Repression of c-myc expression was observed under all of the conditions evaluated. An exposure of cells to 40 microM of the disulfide form of amifostine was the most effective in repressing c- myc, i.e. 27% of control level. A concentration of 4 mM of the disulfide form reduced gene expression to 45% of the control level, while the thiol form was less effective, with 4 mM and 40 microM concentrations reducing c-myc gene expression to 65% and 46% of control levels, respectively.      

Biomechanical analysis of pedicle screw instrumentation systems in a corpectomy model

Five different spinal implants, all using pedicle screw attachment to vertebrae, were examined in a one above/one below corpectomy model, to determine 1) the relative stiffness of each construct, 2) the stresses generated in the implant during loading, and 3) the relative fatigue susceptibility of each implant. Results indicated that the relative axial and torsional stiffnesses were similar for all the implants tested (DKS/Zielke, VSP/Steffee, AO Fixator Interne, Luque plate, AO Notched plate). Hence, each of the devices impart approximately the same stability to the spine in this highly unstable model. Stresses measured at the root of the pedicle screws were found to exceed the endurance limit of stainless steel in those systems in which the pedicle screws were attached rigidly to the plates (VSP/Steffee, AO Fixator Interne). Good agreement was found between the measured stresses and stresses derived from static calculations. Comparisons between the stresses from each implant gave a relative measure of fatigue susceptibility that was validated by in vitro cyclic testing. Implants with stresses exceeding the endurance limit failed during the cyclic test.     

蜜环菌菌丝体化学成分的研究——Ⅵ.蜜环菌癸素(armillaripin)的分离与结构

从人工发酵培养的蜜环菌[Armillaria mellea(Vahl.ex Fr.)Quel.属白蘑科(Tricholometaceae)真菌]菌丝体的石油醚提取物中,经硅胶层析分离得到一新的倍半萜醇芳香酸酯类化合物,命名为蜜环菌癸素(armillaripin)。根据光谱(UV,IR,¹HNMR,¹³CNMR和MS)分析推测其化学结构,并进一步用X-线衍射晶体解析法确证其结构和其相对构型。     

Pterygium treatment with triethylene thiophosphoramide

In this study 146 pterygia were excised from 116 patients. The eyes were treated with Thiotepa eyedrops over four weeks to discourage regrowth. All treatment was carried out by the one surgeon on consecutive patients. The relationship between pinguecula and pterygium is explored, and the pathogenesis of pterygium growth discussed.     

Erosive arthritis in systemic lupus erythematosus: analysis of a distinct clinical and serological subset

Erosive arthritis (EA) in systemic lupus erythematosus (SLE) can be debilitating and deforming with uncertain factors for risk, although antibodies to the A2 hnRNP core protein, known as anti-RA33, have been associated with EA. Two hundred patients under long-term follow-up for SLE were evaluated for EA and associated clinical and serological abnormalities. In addition, sera were tested in a masked fashion for anti-RA33 antibodies in a total of 60 patients: 10 with EA and 50 age-, sex- and ethnically matched controls. Ten of 200 (5%) patients with SLE, mainly non-white women, had EA. There were trends for increased renal involvement (P = 0.06), Sjogren's syndrome (P = 0.07) and Raynaud's phenomenon (P = 0.03) in patients with EA compared to those without EA. Rheumatoid factor (RF) was increased in patients with EA (P < 0.02), as were antibodies to double-stranded DNA (P < 0.05), Sm (P < 0.01) and La/SS-B (P < 0.001). Anti-RA33 antibodies were present in 70% with EA compared to 28% without EA (P < 0.05). RF correlated with anti- RA33 antibodies in patients with EA, but not with the presence of anti- RA33 alone. Thus, anti-RA33 antibodies may identify those patients with SLE who are at risk for EA, and an association with RF suggests a common immune response or pathological mechanism in autoimmune erosive joint disease.