Increased expression of the G gamma and A gamma globin genes associated with a mutation in the A gamma enhancer

We have previously described a unique type of delta beta-thalassemia in a Chinese family characterized by increased expression of the G gamma and A gamma fetal globin genes in the absence of a large deletion in the beta-globlin gene cluster. Our earlier study of the beta-globin gene on this delta beta-thalassemia chromosome showed a promoter mutation in the TATA box. In this report, we describe the results of our study of the fetal globin domain of this delta beta-thalassemia chromosome. We have cloned a 13-kb DNA fragment that includes the G gamma and the A gamma genes and the 3' A gamma enhancer element of this delta beta-thalassemia chromosome. DNA sequence analysis of the G gamma and A gamma-globin genes including their promoters did not show any mutations, but analysis of the putative enhancer element downstream from the A gamma-globin gene showed a C to T substitution 2,401 nucleotides downstream from the A gamma cap site. We performed DNA linkage analysis to determine if this mutation is unique to this chromosome or represents a common polymorphism. Our linkage analysis showed that this mutation is not a common polymorphism and that it is also not an intrinsic part of the haplotype of the chromosome on which it was found. We also studied the interaction of nuclear proteins from erythroid and nonerythroid cells with the DNA sequences surrounding this mutation. We have shown by in vitro DNase I footprinting that this mutation falls within a region that is occupied by a novel DNA-binding protein that binds to this site in nuclear extracts from erythroid, but not nonerythroid cells. The binding of this nuclear protein to DNA appears to be dependent on GATA-1 binding to an adjacent GATA-1 site. We have also developed a new functional assay to compare the activity of the normal and mutant A gamma enhancer elements in erythroid cells. Analysis of the activity of the mutant enhancer shows that the mutation completely eliminates all enhancer activity in this assay. These findings suggest that this mutation of the A gamma enhancer on a chromosome that carries a partially inactivated beta-globin gene may be responsible for the increased expression of both gamma-globin genes seen in this condition.     

射频消融治疗儿童快速性心律失常100例

探讨射频导管消融（ＲＦＣＡ）在治疗儿童快速性心律失常中的临床价值，采用ＲＦＣＡ治疗儿童室上性心动过速（ＳＶＴ）９３例、特发性室性心动过速（ＩＶＴ）７例。结果：ＳＶＴ消融成功率为９１．４％，右侧旁道消融成功率低于左侧旁道及房室结慢径路消融的成功率（８１．８％ｖｓ９６．８％及９６．６％；Ｐ均＜０．０５）。随访３７．３±２０．７个月，８例复发，其中２例发作次数较术前减少，口服普罗帕酮可预防发作，另６例再次消融成功。ＩＶＴ首次消融均成功，随访１９．５±１０．３个月，２例复发，均再次消融成功。全组无并发症发生。结果提示ＲＦＣＡ治疗儿童快速性心律失常是有效的、安全的。     

Production of genetically stable high-titer retroviral vectors that carry a human gamma-globin gene under the control of the alpha-globin locus control region

The ability to generate stable high-titer vectors that give rise to high levels of expression of transduced globin genes in erythroid cells is a prerequisite for effective retroviral-mediated globin gene therapy. The human beta-globin gene with its immediate flanking sequences does not contain all the regulatory elements necessary for regulated high-level and position-independent expression in erythroid cells. The regulatory element known as the beta-globin locus control region (BetaLCR) can provide a linked Beta-globin gene with these properties. However, addition of BetaLCR sequences to a retrovirus carrying a beta-globin gene increases its genetic instability. We have developed a new generation of retroviral vectors in which a human gamma- globin gene is placed under the control of the alphaLCR, the major regulatory element of the alpha-globin gene cluster. We demonstrate that these retroviruses are genetically stable in producer cell lines and can be produced at high titers that exceed 5 x 10(6) colony-forming units (CFU)/mL. In addition, we show that the transduced gamma-globin gene can be expressed in the adult erythroid environment of mouse erythroleukemia (MEL) cells at a level comparable to that of a single endogenous Betamaj-globin gene. These retroviruses can also transduce primary murine bone marrow progenitor cells as efficiently as retroviruses that carry the neomycin resistance (neor) gene. This new generation of globin retroviral vectors may prove useful for gene therapy of human beta-globin gene disorders such as sickle cell disease and beta-thalassemia.     

Lymphadenopathy-associated virus antibodies and T cells in hemophiliacs treated with cryoprecipitate or concentrate

Evidence for exposure to lymphadenopathy-associated virus (LAV) was investigated in 48 patients with hemophilia, 15 of whom had been treated exclusively with single-donor cryoprecipitate. The prevalence of antibodies to LAV in all patients was 53% in 1983 and 63% in 1984, while in patients treated only with cryoprecipitate, the prevalence was 31% in 1983 and 40% in 1984. Patients treated with any concentrate had a seroprevalence of 65% in 1983 and 77% in 1984. Seropositive patients were more likely to have a significant reduction in the ratio of helper to suppressor T cells, absolute numbers of helper T cells, and T cell function in vitro. Seven of 18 patients who were seronegative in 1983 had seroconverted by 1984. The relative risk of seroconversion for patients using any concentrate since 1981 compared with those using cryoprecipitate only was 3.9 (P = .04). Nevertheless, the rate of conversion in the latter group was 18% per year.     

Interactions in the aetiology,presentation and management of synchronous and metachronous adenocarcinoma of the prostate and rectum

Adenocarcinoma of the prostate and rectum are common male pelvic cancers and may present synchronously or metachronously and, due to their anatomic proximity. The treatment of rectal or prostate cancer (in particular surgery and/or radiotherapy) may alter the presentation, incidence and management should a metachronous tumour develop. This review focuses on the interaction between prostatic and rectal cancer diagnosis and management. We have restricted the scope of this large topic to general considerations, management of rectal cancer after prostate cancer treatment and vice versa, management of synchronous disease and cancer follow-up issues.     

The competition of (−)-[3H]nicotine binding by the enantiomers of nicotine,nornicotine and anatoxin-a in membranes and solubilized preparations of different brain regions of rat

Summary In order to characterize the properties of nicotinic acetylcholine receptor (nAChR) subtypes in the CNS, the enantiomers of nicotine, nornicotine and anatoxin-a were studied for their ability to displace (–)-[³H]nicotine binding to membranes and solubilized preparations of different brain regions of rats. In hippocampal membranes, (–)-[³H]nicotine binding was stereo-selectively displaced from two sites by (+)- and (–)-nicotine, as well as by (+)- and (–)-anatoxin-a. (–)-Nicotine displayed a larger proportion of high affinity binding sites than did (+)-nicotine, while the proportions of high and low affinity binding sites for (+)-anatoxin-a was the same as that for (–)-anatoxin-a. In cerebellar membranes, the (–)-[³H]nicotine binding was stereoselectively displaced from a single binding site by nicotine and anatoxin-a with Ki values that did not correspond with their K_H and K_L values observed in hippocampus. The (–)-[³H]-nicotine binding was displaced from a single site by both (+)- and (–)-nornicotine with similar K_i values in both hippocampal and cerebellar membranes. In Triton X-100 solubilized preparations, the (–)-[³H]nicotine binding was displaced from a single site by all of the drugs tested and the Ki values for each individual drug were similar in the cortex, hippocampus and cerebellum. These results provided further evidence for pharmacological heterogeneity of membrane bound nAChRs and clearly indicated that detergent solubilization changed the binding properties of nAChRs in rat brain.Correspondence to X. Zhang at the above address     

Biphasic effect of tacrine on acetylcholine release in rat brain via M1 and M2 receptors

Rat cortical synaptosomes preloaded with [³H]choline were superfused and stimulated with K⁺ in order to investigate the effect of the cholinesterase inhibitor tacrine on the in vitro release of acetylcholine (ACh). Tacrine was found to biphasically both increase (10⁻⁶ and 5 × 10⁻⁶ M) and decrease (10⁻⁵−10-⁻⁴ M) the release of ACh in a concentration-dependent manner. The facilitatory effect of tacrine was prevented by atropine and the M₁ antagonist pirenzepine, whereas the inhibitory effect induced by tacrine was blocked by atropine and the M₂ antagonist AF-DX 116. These results indicate that tacrine causes a biphasic effect on K⁺ stimulated ACh release in the brain via M₁ and M₂ muscarinic receptors. The tacrine induced enhancement of the ACh release occurs at clinical relevant tacrine concentrations and might therefore be of importance for the treatment outcome of Alzheimer's disease.     

紫外分光光度法测定复方酮康唑软膏中酮康唑和氧氟沙星的含量

目的：建立复方酮康唑软膏的含量测定方法。方法：用双波长分光光度法测定酮康唑的含量，用单波长法测定氧氟沙星的含量。结果：两被测组分的平均回收率和相对标准偏差分别为酮康唑１００．３３％和０．３２％；氧氟沙星１００．８５％和０．２７％。结论：方法简便、准确，可用于复方酮康唑软膏的质量控制。