Chediak-Higashi gene in humans. I. Impairment of natural - killer function

Natural-killer (NK)-cell function was profoundly depressed in donors homozygous for the Chediak-Steinbrinck-Higashi syndrome (C-HS) gene when compared with age- and sex-matched normals. This apparent defect was not simply a result of a delayed response because little cytolysis was evident in kinetics experiments even after 24 h of incubation. NK cells from C-HS donors failed to lyse adherent (MDA, CEM, and Alab) or nonadherent (K562 and Molt-4) tumor cell lines or nontransformed human fetal fibroblasts. Therefore, the apparent C-HS defect was not a result of a shift in target selectivities. In addition, the depressed reactivity did not appear to be a result of suppressor cells or factors because: (a) enriched NK populations (nonadherent lymphocytes bearing receptors for the Fc portion of IgG) from C-HS donors were low in NK-cell function, (b) C-HS mononuclear cells did not inhibit the cytotoxicity of normal cells in coculture experiments, and (c) cells from the C-HS donors remained poorly reactive even after culture for up to 7 d. The nature of the defective NK activity in C-HS patients is not clear but may lie within the lytic mechanism rather than at the level of the recognition structure or population size because the frequency of target-binding cells was normal. In vitro NK activity could be partially restored by interferon treatment. Combined with the results presented in the following paper (4), these observations suggest that the C-HS gene causes a selective immunodeficiency disorder, mainly involving NK cells. This finding, in conjunction with the high incidence of spontaneous possibly malignant, lymphoproliferative disorders in these patients, may have important implications regarding the theory of immune surveillance mediated by NK cells.     

BNP/NT-proBNP: what is the best choice in an emergency laboratory?

BNP and NT-proBNP are both well established as diagnostic and prognostic markers for congestive heart failure (CHF). However it remains for the biologist to choose between these two biomarkers depending on his equipment availability. The aim of this study was to compare results obtained with the Biosite Triage BNP assay and the Dade Behring NT-proBNP assay with regards to the clinical status. One hundred twelve patients (average age 76 +/- 13 years) with acute dyspnea were including and stratified by diagnosis at presentation into 3 groups: patients without acute CHF (group I, n=50), patients with non-cardiac dyspnea and CHF history (group II, n=22) and patients with acute CHF (group III, n=40). Levels of both BNP and NT-proBNP were higher among patients with cardiac dyspnea (group III) than among patients with a non-cardiac dyspnea (BNP=740 pg/mL versus 84 pg/mL; p<0.001 / NT-proBNP=7.502 pg/mL versus 499 pg/mL; p<0.001). ROC analysis for BNP or NT-proBNP were not statistically different in patients with acute CHF (group III) compared with patients with a non-cardiac dyspnea (group I + II) (AUC=0.927 versus AUC=0.930, p=0.90). Neither there was a difference between ROC analysis for BNP or NT-proBNP in patients with cardiac dyspnea (group III) compared to patients with a non cardiac dyspnea (group I) (AUC=0.981 versus AUC=0.975, p=0.76).Measurement of BNP or NT-proBNP is of identical interest for the diagnosis of acute CHF in acute dyspnea. The BNP Biosite assay was faster because analysis is performed on whole blood. With regards to analytical performance, the NT-proBNP Dade Behring assay had a higher accuracy and is highly recommended for the follow-up of CHF treatment.     

Hydrophobically Modified Poly(acrylic acid) Using 3‐Pentadecylcyclohexylamine: Synthesis and Rheology

Summary: Hydrophobically modified poly(acrylic acid) was synthesized using 3‐pentadecylcyclohexylamine (3‐PDCA), which was in turn synthesized from 3‐pentadecylphenol, one of the components of cashew‐nut shell liquid (CNSL), a renewable resource material. ¹H NMR spectra confirmed the incorporation of 3‐PDCA onto PAA and a series of HMPs with three different molar concentrations, viz ? 3, 5 and 7 mol‐% of 3‐PDCA, were synthesized. An increase in viscosity with increasing hydrophobic content was observed by rheological measurements. The critical association concentrations were determined using an Ubbelohde viscometer and a controlled stress rheometer. The stability of HMPs towards temperature and shear was studied. Rheological measurements showed that there was a steady increase in viscosity with increase in hydrophobe content due to the formation of reversible networks. These polymers exhibited gel‐like behavior at low concentrations (≥2 wt.‐%) with an apparent yield stress (ca. 10 Pa) and showed shear thinning properties (non‐Newtonian). However, below a critical concentration, c [η], they showed Newtonian behavior.

η_sp of unmodified and modified PAA‐Na at various polymer concentrations.     

Social recognition memory requires protein synthesis after reactivation

Recent evidence indicates that reactivation of consolidated memories returns them to a protein-synthesis-dependent state called reconsolidation. The hypothesis that memories reconsolidate has never been assessed in social memory. The authors tested whether sheep (Ovis aries) mothers' memory of their lambs undergoes reconsolidation upon reactivation. After 7 days of mother-young contact, ewes were separated from their lambs for 8 hr, after which the lambs were reintroduced to their mothers for a 10-min reactivation session. Before reactivation, mothers received a subcutaneous injection of either the protein-synthesis inhibitor cycloheximide (CY, 1 mg/kg) or vehicle. Mothers' lamb memory was tested 1 hr (short-term memory [STM]) or 16 hr (long-term memory [LTM]) after reactivation. Mothers treated with CY exhibited intact STM but deficient LTM. CY injection without reactivation or before presentation of an alien lamb induced no deficit in LTM. CY-induced LTM deficit was alleviated by (a) introducing a reminder just before the LTM test, (b) extending mother-young contact, and (c) preventing suckling by the familiar lamb during reactivation. Thus, reconsolidation can be shown to exist in social memory, and some of its boundary conditions are discussed.     

Detection of the Klebsiella pneumoniae carbapenemase type 2 Carbapenem-hydrolyzing enzyme in clinical isolates of Citrobacter freundii and K. oxytoca carrying a common plasmid

The Klebsiella pneumoniae carbapenemase (KPC) was detected in carbapenem-resistant isolates of Citrobacter freundii and Klebsiella oxytoca recovered from different patients in a Michigan hospital. Restriction analysis and hybridization with a KPC-specific probe showed the bla(KPC-2) genes of these two genera of the family Enterobacteriaceae are carried on a common plasmid.     

Human renal cell carcinoma xenografts in SCID mice: tumorigenicity correlates with a poor clinical prognosis.

To establish human renal cell carcinoma (RCC) xenografts for preclinical studies, 55 renal tumors (33 primary and 22 metastatic lesions) were transplanted subcutaneously into severe combined immunodeficient mice. Twenty of 49 evaluable tumors (40.8%) grew with a median latency period of 89 days (36 to 209 days) from the day of engraftment. Tumor growth was stabilized after the fifth passage with a median time between passages of 38 days (19 to 80 days). Tumorigenicity was correlated with the metastatic phenotype of the tumor (54% success rate, p = 0.007) and with reduced survival of patients. Despite a possible evolution of histological features and tumor grading, established RCC xenografts were comparable to parental tumors, as assessed by karyotype and DNA-ploidy analyses. Molecular cytogenetic analysis also revealed specific genetic alterations characterizing distinct RCC types that were constant in parental and corresponding xenografts. In addition, this xenograft model has permitted the selection of minor tumor subclones with a proliferative advantage and minimal overexpressed chromosomal regions. We conclude that severe combined immunodeficient mice are useful recipients for the establishment of long-term RCC xenografts that can be used as valuable tools to evaluate the activity of new therapeutic approaches and to study biological parameters determining in vivo aggressiveness of human RCC.     

In vitro evidence for both the nucleus and cytoplasm as subcellular sites of pathogenesis in Huntington's disease

A unifying feature of the CAG expansion diseases is the formation of intracellular aggregates composed of the mutant polyglutamine-expanded protein. Despite the presence of aggregates in affected patients, the precise relationship between aggregates and disease pathogenesis is unresolved. Results from in vivo and in vitro studies of mutant huntingtin have lead to the hypothesis that nuclear localization of aggregates is critical for the pathology of Huntington's disease (HD). We tested this hypothesis using a 293T cell culture model system that compared the frequency and toxicity of cytoplasmic and nuclear huntingtin aggregates. We first assessed the mode of nuclear transport of N-terminal fragments of huntingtin, and show that the predicted endogenous NLS is not functional, providing data in support of passive nuclear transport. This result suggests that proteolysis is a necessary step for nuclear entry of huntingtin. Additionally, insertion of nuclear import or export sequences into huntingtin fragments containing 548 or 151 amino acids was used to reverse the normal localization of these proteins. Changing the subcellular localization of the fragments did not influence their total aggregate frequency. There were also no significant differences in toxicity associated with the presence of nuclear compared with cytoplasmic aggregates. The findings of nuclear and cytoplasmic aggregates in affected brains, together with these in vitro data, support the nucleus and cytosol as subcellular sites for pathogenesis in HD.