Recognition of virus-infected cells by natural killer cell clones is controlled by polymorphic target cell elements

Natural killer (NK) cells provide a first line of defense against viral infections. The mechanisms by which NK cells recognize and eliminate infected cells are still largely unknown. To test whether target cell elements contribute to NK cell recognition of virus-infected cells, human NK cells were cloned from two unrelated donors and assayed for their ability to kill normal autologous or allogeneic cells before and after infection by human herpesvirus 6 (HHV-6), a T-lymphotropic herpesvirus. Of 132 NK clones isolated from donor 1, all displayed strong cytolytic activity against the NK-sensitive cell line K562, none killed uninfected autologous T cells, and 65 (49%) killed autologous T cells infected with HHV-6. A panel of representative NK clones from donors 1 and 2 was tested on targets obtained from four donors. A wide heterogeneity was observed in the specificity of lysis of infected target cells among the NK clones. Some clones killed none, some killed only one, and others killed more than one of the different HHV-6-infected target cells. Killing of infected targets was not due to complete absence of class I molecules because class I surface levels were only partially affected by HHV-6 infection. Thus, target cell recognition is not controlled by the effector NK cell alone, but also by polymorphic elements on the target cell that restrict NK cell recognition. Furthermore, NK clones from different donors display a variable range of specificities in their recognition of infected target cells.     

Changes in mood and hormone levels after rapid-rate transcranial magnetic stimulation (rTMS) of the prefrontal cortex

A person's reality and definition of self are socially constructed; ethnicity is integrally involved in this process. Clinical work is successful if the client constructs a self with a sense of positive self-esteem and empowerment. The profession views social workers' use of self as important in successful clinical work, especially with clients ethnically different from themselves. This article provides a framework adapted from a constructivist perspective for the clinician's skillful use of self in therapeutic discourse. The framework consists of five stances the clinician can use in transcending the discomfort he or she may experience in a cross-cultural clinical situation. Use of these stances facilitates clients' ethnic validation, which is essential to positive therapeutic outcomes. This article uses case examples to illustrate the use of the framework.     

A prospective, multicenter study of a pneumonia practice guideline

Two-dimensional 1H detected 13C NMR spectroscopy has been used to study the intracellular metabolism of [3-(13)C]pyruvate in Halobacterium salinarium. The method, resulting in considerable improvement in spectral resolution and signal-to-noise ratio, is well suited for studying transient metabolic intermediates. Pyruvate utilization by the bacterium is a double exponential function with rate constants of 49.13 and 4.67x10(-3) per min. The relative 13C enrichment is the fastest for C-3 glutamate. Glutamate C-4 labeling decreases initially and increases later on during incubation, while glutamine C-3 is high to begin with and exhibits a declining trend. The glutamate labeling indicates a high initial flux through pyruvate carboxylase and extensive randomizing of the label in the tricarboxylic acid cycle.     

Isolated plantar venous thrombosis. Report of a case

We report the case of a patient with isolated plantar thrombophlebitis as a post operative complication of saphenectomy. Risk factors such as prolonged bed rest, perioperative inflammation and surgery of the greater saphenous vein itself should be considered. Moreover multiple episodes of superficial venous thrombosis had already occurred as complication of the superficial venous insufficiency. Literature on this unusual outcome is lacking. Ultrasound imaging revealed this superficial thrombosis. Usual echographic signs (non compressible vein, hypoechogenicity of the vessel lumen) can be found. The main problem is to differentiate veins from adjacent tendinous structures. Slow mobilisation of the toes and comparative analysis on contralateral foot are helpful. Thrombosis of the plantar veins must be considered as a possible diagnosis of unexplained plantar unilateral pains. Development of ultrasonic investigations and knowledge of its occurrence could further improve its diagnosis.     

Over-production of stereoselective nitrile hydratase from Pseudomonas putida 5B in Escherichia coli: activity requires a novel downstream protein

The stereoselective nitrile hydratase (NHase) from Pseudomonas putida 5B has been over-produced in Escherichia coli. Maximal enzyme activity requires the co-expression of a novel downstream gene encoding a protein (P14K) of 127 amino acids, which shows no significant homology to any sequences in the protein database. Nitrile hydratase produced in transformed E. coli showed activity as high as 472 units/mg dry cell (sixfold higher than 5B), and retained the stereoselectivity observed in the native organism. Separated from the end of the beta subunit by only 51 bp, P14K appears to be part of an operon that includes the alpha and beta structural genes of nitrile hydratase, and other potential coding sequences.     

Selection-dependent trends of autogeny and blood feeding in an autogenous strain of Culex tarsalis (Diptera:Culicidae)

The purpose of this report is to examine the outcomes for patients with an underlying diagnosis of malignancy who have had Greenfield vena caval filters placed for protection from pulmonary embolism, and to identify areas requiring further study. This was a retrospective review of data obtained from the Greenfield filter registry and the University of Michigan Tumor Registry for 166 patients treated at the University of Michigan Medical Center between January 1988 and June 1994. The 84 men and 82 women (mean age 57.8 years) had a mean survival time of 10 (range 1-68) months. This differs significantly from patients in the filter registry who do not have malignancy (P<0.0001). Some 51% experienced recurrence of their malignancy at a mean of 20 months; this timing corresponds to development of new or recurrent thrombembolism and filter placement. Distant metastases were present in 72% of patients at the time of filter placement. In conclusion, as anticipated, filter patients with malignancy have a significantly shorter survival time than those with other concurrent diseases. A temporal association between the progression of the malignancy and the occurrence of thromboembolism is observed in this population and requires further study. Future studies regarding the use of vena caval filters in these patients and the role of diagnostic screening for deep venous thrombosis and occult recurrence of malignancy should focus on efficacy, safety, cost and patient quality of life rather than on survival.     

The expression of constitutively active isotypes of protein kinase C to investigate preconditioning

The role of protein kinase C (PKC) in ischemic preconditioning remains controversial because of difficulties with both its measurement and pharmacological manipulation. We investigated preconditioning in isolated neonatal rat cardiocytes by expressing constitutively active isotypes of PKC. Observations at differing durations of simulated ischemia suggested beta-galactosidase (beta-gal) activity reflected viability within transfected myocytes. Preconditioning with 90 min of ischemia significantly increased beta-gal activity and myocyte survival after 6 h of ischemia; an effect abolished by PKC inhibitors. After co-transfection with plasmids encoding beta-gal and either constitutively active mutants of PKC-delta, PKC-alpha, wild type PKC-delta, or empty vector, cardiocytes were subjected to 6 h of ischemia. Only PKC-delta, rendered constitutively active by a limited deletion within the pseudosubstrate domain, consistently increased resistance to simulated ischemia (beta-gal activity was 85.6 +/- 11.9% versus 53.7 +/- 6.5% (p 相似文献