Cro mutants of phage 434.

Phage 434 cro⁴³⁴ mutants have been isolated and characterized as plaque formers on groN bacteria, which block wild-type 434 and λ development at the level of action of the N gene product (Georgopoulos, 1971). Like the corresponding λ cro^λ mutants, they map within the immunity region and to the right of the cI gene, they overproduce the exonuclease gene product, they are unable to propagate on wild-type bacteria (especially at 42°), and in mixed infections they suppress the growth of heteroimmune but not homoimmune cro⁺ phage.     

催产素对妊娠末期大鼠蜕膜细胞内游离钙的刺激作用

妊娠末期催产素刺激子宫蜕膜细胞产生与分娩有关的前列腺素,但其作用方式仍未知。本实验分离妊娠19d大鼠蜕膜细胞,测定了催产素作用后蜕膜细胞内游离钙的变化,结果加入0.001～1μmol·L^-1催产素后,蜕膜细胞内[Ca²⁺]i出现瞬息增加,其峰值与催产素浓度呈剂量依赖关系,且此作用有自身钝化现象。说明催产素可能激活妊娠末期大鼠蜕膜细胞内的肌醇磷酯蛋白激酶C系统。给妊娠末期大鼠ip硫酸去氢表雄酮钠盐后分离的蜕膜细胞,催产素作用引起[Ca²⁺]i瞬息增加峰值较对照升高。     

Recovery of T cell subsets after autologous bone marrow transplantation is mainly due to proliferation of mature T cells in the graft

In 22 patients with malignancies, treated with high-dose chemoradiotherapy and autologous bone marrow transplantation (BMT), peripheral blood T cell subsets and functions were studied. In ten cytomegalovirus (CMV)-negative patients, CD4+ and CD8+ T cells (representing T cells of the helper/inducer phenotype and T cells of the suppressor/cytotoxic phenotype, respectively), recovered slowly and simultaneously. In 12 CMV-positive patients, however, CD8+ T cells recovered more rapidly than CD4+ T cells and rose to increased counts. No T cells with an immature phenotype (CD1+, OKT6+) were observed. Lymphocyte stimulation by herpes simplex virus infected fibroblasts (and by CMV-infected fibroblasts in CMV-positive patients) in contrast remained high and even increased after BMT in both groups. These data indicate that T cell recovery after autologous BMT is mainly due to proliferation of mature T cells present in the BM graft and not to generation of new T cells from T cell precursors.     

Chlorambucil therapy in hairy cell leukemia: effects on lipid composition and lymphocyte subpopulations

Two patients with progressive hairy cell leukemia following splenectomy were treated with low-dose daily chlorambucil. Both had an objective hematologic response as determined by a return to normal hematocrit and platelet count. This was also reflected in the mononuclear cell fraction by the normalization of cholesterol content, cholesterol/phospholipid ratio, and the lymphocyte subpopulations. This article confirms previous reports on the efficacy of chlorambucil in this setting and describes some morphological, and biochemical concomitant events.     

MR imaging of facial nerve enhancement in Bell palsy or after temporal bone surgery

The authors evaluated magnetic resonance (MR) images obtained with intravenously administered gadolinium in ten patients who had facial paralysis and no facial nerve tumor. In patients with either Bell palsy (four patients) or facial paralysis after temporal bone surgery (six patients), intratemporal facial nerve enhancement was seen. Facial nerve enhancement on MR images proved to be a nonspecific finding.     

High-dose chemotherapy in adult soft tissue sarcoma

Soft tissue sarcomas represent a rare and heterogeneous disease. Only few drugs have been identified to be active, with doxorubicin, epirubicin and ifosfamide being the only agents with response rates above 20%. Combination chemotherapy results in higher response rates, however, superiority against single agent chemotherapy in terms of survival has not been established yet. Since a dose-response relationship is suggested for the anthracyclines and especially ifosfamide, high-dose or dose-intensive chemotherapy with bone marrow or stem cell support has been evaluated by several investigators. The studies are usually small, and included a very heterogeneous group of patients. Randomized trials have not been done, so that definite conclusions cannot be drawn to date. High-dose chemotherapy in soft tissue sarcoma has to be considered highly investigational and should not be performed outside clinical trials. Future studies should be focused on the development of active regimens, resulting in complete remission rates, that can be expected to translate into longer survival. Finally, well designed and appropriately powered randomized trials, using established prognostic and predictive factors, should be carried out, preferably in younger patients and in the context of a potentially curative multimodality approach.     

Single Nucleotide Differences (SNDs) Continue to Contaminate the dbSNP Database With Consequences for Human Genomics and Health

It has been established that up to 8.3% of the biallelic coding SNPs present in dbSNP are actually artefactual polymorphism‐like errors, previously termed single nucleotide differences, or SNDs. In this study, a previous analysis of SNPs in dbSNP was extended and updated to examine how the incidence of SNDs has changed over an intervening five year period. The incidence of SNDs was found to be lower than in the previous analysis at 2.2% of all biallelic SNPs. There was only a modest reduction in the percentage of SNDs in the original set of biallelic coding SNPs tested. This suggests that the overall reduction in the incidence of SNDs over the intervening 5‐year period is related to an improvement in SNP detection methods and more rigorous curation, rather than efforts to ameliorate the presence of SNDs. We note that SNDs contaminating the dbSNP may lead to erroneous conclusions on human conditions.     

Neurite outgrowth on muscle cell surfaces involves extracellular matrix receptors as well as Ca2+-dependent and -independent cell adhesion molecules.

To identify the molecules on the neuronal surface that mediate axonal growth on myotubes, we have examined neurite formation by ciliary neurons grown on myotubes in the absence or presence of specific antibodies. Dramatic inhibition of neurite outgrowth was seen only when antibodies blocked simultaneously the functions of two cell adhesion molecules--neural cell adhesion molecule (N-CAM) and neural Ca2+-dependent CAM (N-Cal-CAM)--and the neuronal receptors for several extracellular matrix (ECM) proteins. Although the antibody used to block ECM receptors (JG22) has been shown to eliminate almost all neurite growth on ECMs, it had only small effects on neurite growth on myotubes, reducing somewhat the length of neurites. Similarly, antibodies to the two CAMs, when used alone, had no detectable effects on neurite length and, when used together, had only small inhibitory effects on neurite growth. Combination of anti-ECM receptor (JG22) with antibodies to either CAM, however, greatly shortened the length of neurites. These results imply that ECM receptors and the CAMs N-CAM and N-Cal-CAM are major macromolecules used by neuronal growth cones for interactions with myotubes. Each provides a distinct mechanism for regulating growth cone motility.     

Leukocytopenia, Thrombocytopenia and Fever Related to Piperacillin/Tazobactam Treatment – A Retrospective Analysis in 38 Children with Cytic Fibrosis

Summary Bone marrow suppression is an important adverse reaction to most betalactam antibiotics. Recently it was suggested that piperacillin/tazobactam (PT) also may cause bone marrow toxicity. We retrospectively analyzed 100 IV antibiotic treatment courses (mean duration 12.5 days) in 38 patients (median age 14 years) with cystic fibrosis (CF) who were treated in our hospital. Of the patients receiving PT (84%), 6 patients (18.75% of PT-treated patients, 10.3% of PT treatment courses) developed fever, malaise and headache during treatment without signs of acute infection. In one patient definite thrombocytopenia and neutropenia, in two others a milder decrease in leukocyte and thrombocyte counts was observed after the onset of fever. The events were time- and dose-dependent occurring between day 11 and 15 of treatment. Treatment courses lasted longer (14.2 vs 11.3 days; p < 0.05) and patients had received a higher cumulative dose of PT (4919 ± 1975 mg/kg b.w. vs 3161 ± 1635 mg/kg; p < 0.02, Student's t-test) in the affected group than in the unaffected group. After discontinuation of PT, fever subsided within 24 h and blood cell counts normalized. We hypothesize that these fever episodes and changes of blood parameters are related to PT therapy. Received: February 8, 1999 · Accepted: September 17, 1999