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.
ηsp of unmodified and modified PAA‐Na at various polymer concentrations. 相似文献
Sam68 has been initially described as a substrate of src kinases during mitosis in fibroblasts. Recent evidence suggests that in T lymphocytes Sam68 may act as an adaptor protein and participate in the early biochemical cascade triggered after CD3 stimulation. A direct interaction between Sam68 and the two src kinases involved in T cell activation, p59fyn and p56lck, as well as a partnership of Sam68 with various key downstream signaling molecules, like phospholipase Cγ-1 and Grb2, has been shown. In this study we analyze the contribution of p56lck, as well as the role of ZAP-70, the second class of protein tyrosine kinase involved in T cell activation, in Sam68 tyrosine phosphorylation in the human Jurkat T cell line. Using the src inhibitor PP1 [4-amino-5-(4-methylphenyl)7-(t-butyl) pyrazolo [3,4-d] pyrymidine] and cell variants with defective expression of p56lck or expressing a dominant negative form of ZAP-70, we demonstrate that, while both p56lck and ZAP-70 are dispensable for the low constitutive phosphorylation of Sam68 observed in Jurkat cells, a cooperation between the two kinases is required to increase its rapid phosphorylation observed in vivo after CD3 stimulation. We also show that recombinant forms of both p56lck and ZAP-70 phosphorylate Sam68 in vitro. However, using CD2 stimulated cells, we observe that p56lck activation by itself does not induce Sam68 tyrosine phosphorylation. We conclude that p59lck and p56lck differently participate in regulating the phosphorylation state of Sam68 in T cells and that ZAP-70 may contribute to Sam68 tyrosine phosphorylation and to the specific recruitment of this molecule after CD3 stimulation. 相似文献
Pontine omnipause neurons (OPNs) have so far been considered as forming a homogeneous group of neurons whose tonic firing
stops during the duration of saccades, when the head is immobilized. In cats, they pause for the total duration of gaze shifts,
when the head is free to move. In the present study, carried out on alert cats with fixed heads, we present observations made
during self-initiated saccades and during tracking of a moving target which show that the OPN population is not homogeneous.
Of the 76 OPNs we identified, 39 were found to have characteristics similar to those of previously described neurons, ”saccade”
(S-) OPNs: (1) the durations of their pauses were significantly correlated with the durations of saccades; (2) the discharge
ceased shortly before saccade onset and resumed before saccade end; (3) visual responses to target motion were excitatory;
and (4) during tracking, S-OPNs interrupted the discharge for the duration of saccades and resumed firing during perisaccadic
”drifts”. However, the characteristics of 37 neurons (”complex” (C-) OPNs) were different: (1) the pause duration was not
correlated with the duration of self-initiated saccades; (2) time lead of pause onsets relative to saccades was, on average,
longer than in the group of S-OPNs, and firing resumed after the saccade end; (3) visual target motion suppressed tonic discharges;
and (4) during tracking, firing was interrupted for the total duration of gaze shifts, including not only saccades but also
perisaccadic ”drifts”. We conclude that cat OPNs can be subdivided into two main groups. The first comprises neurons whose
firing patterns are compatible with gating individual saccades (”saccade” OPNs). The second group consists of ”complex” OPNs
whose firing characteristics are appropriate to gate total gaze displacements rather than individual saccades. The function
of these neurons may be to disinhibit pontobulbar circuits participating in the generation of saccade sequences and associated
perisaccadic drifts.
Received: 20 January 1998 / Accepted: 22 October 1998 相似文献
The new VITEK 2 system (bioMérieux) was evaluated at two independent sites with the identification card for gram-negative bacilli (ID-GNB card). Of the 845 strains tested, which represented 70 different taxa belonging to either the family Enterobacteriaceae or the nonenteric bacilli, 716 (84.7%) were correctly identified at the species level. Thirty-two (3.8%) additional strains were identified to the species level after the performance of simple, rapid manual tests (oxidase, hemolysis, indole reaction, motility, and pigmentation). For 80 (9.5%) strains, these additional tests did not lead to an identification at the species level but the correct species identification was given among the organisms listed. Only 7 (0.8%) strains were misidentified, and 10 (1.2%) were not identified. Mistakes were randomly distributed over different taxa. Due to the new, more sensitive fluorescence-based technology of the VITEK 2 system, final results were available after 3 h. Since our evaluation was mainly a stress test, it is predicted that the VITEK 2 system in conjunction with the ID-GNB card would perform well under conditions of a routine clinical laboratory in identifying members of the family Enterobacteriaceae and selected species of nonenteric bacteria. This system is a promising, highly automated new tool for the rapid identification of gram-negative bacilli from human clinical specimens. 相似文献
The OPA1 gene, encoding a dynamin-related GTPase that plays a role in mitochondrial biogenesis, is implicated in most cases of autosomal dominant optic atrophy (ADOA). Sixty-nine pathogenic OPA1 mutations have been reported so far. Most of these are truncating mutations located in the GTPase domain coding region (exons 8-16) and at the 3'-end (exons 27-28). We screened 44 patients with typical ADOA using PCR-sequencing. We also tested 20 sporadic cases of bilateral optic atrophy compatible with ADOA. Of the 18 OPA1 mutations found, 14 have never been previously reported. The novel mutations include one nonsense mutation, 3 missense mutations, 6 deletions, one insertion and 3 exon-skipping mutations. Two of these are de novo mutations, which were found in 2 patients with sporadic optic atrophy. The recurrent c.2708_2711delTTAG mutation was found in 2 patients with a severe congenital presentation of the disease. These results suggest that screening for OPA1 gene mutations may be useful for patients with optic atrophy who have no affected relatives, or when the presentation of the disease is atypical as in the case of early onset optic atrophy. 相似文献
Summary The relationship between the concentrations of 5-hydroxyindoleacetic acid (5-HIAA) in the CSF and in the striatum has been evaluated in the rat by measuring the levels of this metabolite in ventricular CSF (by liquid chromatography coupled with electrochemical detection) and in the striatal extracellular fluid (byin vivo voltammetry) after administration of inhibitors of serotonin synthesis or degradation. Pargyline, NSD 1015 and-propyldopacetamide all caused an exponential decline of 5-HIAA in both CSF and striatum. For a given drug, the rate constants for 5-HIAA disappearance were identical in the CSF and in the striatal extracellular fluid. These results confirm the view that CSF 5-HIAA may serve as a good index of brain serotonin turnover. 相似文献
The effect of 3 anthracene derivatives, mitoxantrone, ametantrone, bisantrene, on 4 normal human bone marrows, was studied using the myeloid stem cell assay developed by Pike and Robinson, in order to define to what extent this test could be used to predict the relative clinical hematologic toxicity of new anticancer agents. For the 3 drugs, an exponential relationship between colony survival and drug concentration was found, but was much steeper for mitoxantrone (slope = -195.2 ± 8.8/g/ml) than for ametantrone (slope = 5.1 ± 1.0/g/ml, p0.001) and bisantrene (slope = 7.1 ± 0.3/g/ml, p0.001). The difference of slope between ametantrone and bisantrene was of borderline significance (p0.05). The ratios of concentrations inducing a 50% growth inhibition for mitoxantrone versus bisantrene and for ametantrone versus bisantrene were close to the corresponding ratios of concentrations inducing a 90% growth inhibition. The relative in vitro toxicities reproduce very well the relative myelosuppression observed in clinical trials with mitoxantrone versus bisantrene but the results were less satisfactory for the comparison of these 2 agents with ametantrone. In addition, our data suggest that, for these 3 compounds, intrinsic myeloid progenitor sensitivity is a major determinant of leukopenia. 相似文献
Maternal and Child Health Journal - Data are scarce regarding the prevalence and predictors of perinatal mood and anxiety disorders (PMADs) among Black women. The purpose of this study was to... 相似文献