Respiratory effects in two-dimensional Fourier transform MR imaging

Respiratory and other regular motions during two-dimensional Fourier transform magnetic resonance imaging produce image artifacts consisting of local blurring and more or less regularly spaced "ghost" images propagating along the direction of the phase-encoding magnetic field gradient. The patterns of these ghost artifacts can be understood in terms of the technique of image production and basic properties of the discrete Fourier transform. This understanding permits, without respiratory gating, production of images of improved quality in body regions in which there is significant respiratory motion. In particular, the ghosts can be maximally separated from the primary image by choosing intervals between phase-encoding gradient pulse increments that are equal to one-half the respiratory period; they can be minimally separated by choosing an interval equal to the respiratory period. Increasing the number of signal averages between each phase-encoding increment decreases the intensity of the ghosts.     

Osteopetrosis: MR characteristics at 1.5 T

Four patients with proved osteopetrosis (three with the infantile malignant form and one with the benign form) were examined with magnetic resonance imaging at 1.5 T. All patients were studied in the coronal and sagittal planes using both short and long repetition time/echo time sequences. The infantile malignant form was characterized by a complete lack of signal from the marrow alternating with a signal intensity equivalent to that of the intervertebral disks, resulting in a "stepladder" appearance. In the benign form or after successful marrow transplantation in the infantile malignant form, intermediate or high signal intensity in the vertebrae was noted, suggesting the presence of some marrow elements.     

Pregnancy: The effect of dose of mifepristone and gestation on the efficacy of medical abortion with mifepristone and misoprostol

Although it has been demonstrated that a combination of mifepristoneand a prostaglandin is an effective method of inducing abortionin early pregnancy, the optimum dose of the antigestogen isunknown. Women (n = 220) requesting abortion in early pregnancy(63 days amenorrhoea) were randomized to receive a single doseof either 600 or 200 mg mifepristone followed 48 h later bya single dose of 600 µg misoprostol by mouth. The percentageof women who had a complete abortion (93.6% confidence interval90.4–95.5%) was identical in the two groups. There wasno significant difference in the number of women who passedthe fetus within 4 h of receiving the prostaglandin (64 versus74%), the days of bleeding (14.6 ± 1.1 versus 15.3 ±0.9) nor in the onset of the next period (39.7 ± 1.3versus 36.7 ± 1.3) respectively between the groups receiving200 or 600 mg mifepristone. However, the complete abortion ratewas significantly higher in women 49 days compared to women50–63 days amenorrhoea (97.5 versus 89.1% respectively;P < 0.02). There was no difference in any of the other parametersat different weeks of gestation. We conclude: (i) that the recommendeddose of mifepristone could be reduced from 600 to 200 mg withoutloss of clinical efficacy, (ii) that the combination of mifepristoneand 600 µg misoprostol is a highly effective alternativeto vacuum aspiration for inducing abortion in women < 50days amenorrhoea and (iii) at gestation >56 days, this combinationmay result in too many incomplete abortions to be clinicallyacceptable.     

带有蛋白转导结构域的bcr/abl癌蛋白片段表达及其跨膜转运

0　引言　人类免疫缺陷病毒 (human immunodeficiencyvirus,HIV) - 1编码的反式激活蛋白 TAT具有独特的跨膜运转方式 ,而且有转导速度快 ,效率高的特点 ,被称为蛋白转导结构域 (protein transduction domain,PTD) [1 ,2 ] .本研究用PCR扩增了慢性粒细胞白血病慢粒 bcr/ abl融合蛋白的基因片段 ,在其 5′端融合 PTD结构域的编码区后在大肠杆菌中进行了表达 .表达产物经纯化后 ,加入培养的 HL 6 0细胞 ,表达的蛋白可直接进入细胞内 .这一结果为用外源蛋白负载(L oading)免疫细胞提供了新的途径 .1　材料和方法1.1　 DNA重组　人工合…     

下消化道出血221例分析

0　引言　下消化道出血是消化科的常见病 ,是指十二指肠空肠移行部 ,屈氏韧带以下的小肠和大肠疾病引起的肠道出血 .有人认为一般不包括痔和肛裂出血 [1 ] .临床最常见为慢性出血 ,但有时出血量大危及生命 ,需要做紧急处理 ,现将我院1992 - 0 1/ 1999- 0 8门诊及病房收治的 2 2 1例下消化道出血进行分析 ,报告如下 :1　临床资料　男 12 0例 ,女 10 1例 ,年龄 14～ 72 (平均 42 )岁 ,病程 16 h～ 10 a.患者分别以脓血便、暗红色血便、鲜血便或果酱色血便为主诉前来就诊 ,其中有休克症状的大出血者6例 .血 Hb<110 g·L- 1 40例 ,<80 g·L- 1…     

Hydrogen peroxide inhibits gap junctional intercellular communication in glutathione sufficient but not glutathione deficient cells

Cell to cell communication via gap junctions is essential in the maintenance of the homeostatic balance of multicellular organisms. Aberrant intercellular gap junctional communication (GJIC) has been implicated in tumor promotion, neuropathy and teratogenesis. Oxidative stress has also been implicated in similar pathologies such as cancer. We report a potential link between oxidative stress and GJIC. Hydrogen peroxide, a known tumor promoter, inhibited GJIC in WB-F344 rat liver epithelial cells with an I50 value of 200 microM. Inhibition of GJIC by H2O2 was reversible as indicated by the complete recovery of GJIC with the removal of H2O2 via a change of fresh media. Free radical scavengers, such as t-butyl alcohol, propylgallate, and Trolox, did not prevent the inhibition of GJIC by H2O2, which indicated that the effects of H2O2 on GJIC was probably not a consequence of aqueous free radical damage. The depletion of intracellular GSH reversed the inhibitory effect of H2O2 on GJIC. The treatment of glutathione- sufficient cells with H2O2 resulted in the hyperphosphorylation of connexin43, which is the basic subunit of the hexameric gap junction protein, as determined by Western blot analysis. TPA, a well-known tumor promoter, also inhibits GJIC via hyperphosphorylation of GJIC, which is a result of protein kinase-C activation. However, H2O2 also induced hyperphosphorylation in GSH-deficient cells that had normal rates of GJIC. Therefore, the mechanism of GJIC inhibition must be different from the TPA-pathway and involves GSH.      

Hepatitis C virus genotype 6:Virology,epidemiology,genetic variation and clinical implication

Hepatitis C virus(HCV)is a serious public health problem affecting 170 million carriers worldwide.It is a leading cause of chronic hepatitis,cirrhosis,and liver cancer and is the primary cause for liver transplantation worldwide.HCV genotype 6(HCV-6)is restricted to South China,South-East Asia,and it is also occasionally found in migrant patients from endemic countries.HCV-6 has considerable genetic diversity with23 subtypes(a to w).Although direct sequencing followed by phylogenetic analysis is the gold standard for HCV-6 genotyping and subtyping,there are also now rapid genotyping tests available such as the reverse hybridization line probe assay(INNO-LiPAⅡ;Innogenetics,Zwijnaarde,Belgium).HCV-6 patients present with similar clinical manifestations as patients infected with other genotypes.Based on current evidence,the optimal treatment duration of HCV-6 with pegylated interferon/ribavirin should be 48 wk,although a shortened treatment duration of 24 wk could be sufficient in patients with low pretreatment viral load who achieve rapid virological response.In addition,the development of direct-acting antiviral agents is ongoing,and they give high response rate when combined with standard therapy.Herein,we review the epidemiology,classification,diagnosis and treatment as it pertain to HCV-6.