Carbon 13 NMR study of nonenzymatic reactions of pyridoxal 5'-phosphate with selected amino acids and of related reactions.
Carbon 13 nuclear magnetic resonance spectroscopy has been used to monitor the nonenzymatic reactions of pyridoxal 5'-phosphate with glycine, alanine, valine, serine, and with several other model compounds. Isotopically enriched amino acids were employed so that low concentrations could be utilized while still allowing relatively rapid acquisition of spectral data. The results for alanine and serine are particularly noteworthy in that alanine is deaminated to pyruvate and pyruvate is aminated to alanine, but contrary to the enzymatic reactions of various serine dehydratases wherein serine is converted to pyruvate, the nonenzymatic reaction utilizing serine results in hydroxypruvate rather than pyruvate formation. In the reverse reaction, hydroxypyruvate is aminated to serine but very inefficiently relative to the amination of pyruvate to alanine. The experimental results have been formulated into a proposed reaction mechanism for deamination of amino acids by pyridoxal-P. (+info)
Hierarchical cluster analysis applied to workers' exposures in fiberglass insulation manufacturing.
The objectives of this study were to explore the application of cluster analysis to the characterization of multiple exposures in industrial hygiene practice and to compare exposure groupings based on the result from cluster analysis with that based on non-measurement-based approaches commonly used in epidemiology. Cluster analysis was performed for 37 workers simultaneously exposed to three agents (endotoxin, phenolic compounds and formaldehyde) in fiberglass insulation manufacturing. Different clustering algorithms, including complete-linkage (or farthest-neighbor), single-linkage (or nearest-neighbor), group-average and model-based clustering approaches, were used to construct the tree structures from which clusters can be formed. Differences were observed between the exposure clusters constructed by these different clustering algorithms. When contrasting the exposure classification based on tree structures with that based on non-measurement-based information, the results indicate that the exposure clusters identified from the tree structures had little in common with the classification results from either the traditional exposure zone or the work group classification approach. In terms of the defining homogeneous exposure groups or from the standpoint of health risk, some toxicological normalization in the components of the exposure vector appears to be required in order to form meaningful exposure groupings from cluster analysis. Finally, it remains important to see if the lack of correspondence between exposure groups based on epidemiological classification and measurement data is a peculiarity of the data or a more general problem in multivariate exposure analysis. (+info)
A new rapid technique for the fixation of thyroid gland surgical specimens.
One of the main diagnostic problems in thyroid pathology is to distinguish between follicular adenoma and follicular carcinoma. Thorough sampling of the nodule's capsule is recommended in order to identify capsular invasion. However, during the hardening of the tissue, by the usual fixatives the capsule shrinks and rolls downwards and sometimes the capsule separates from the remaining tissue. The present work evaluates the use of "Lymph Node Revealing Solution" (LNRS) for the rapid fixation (2h) of different thyroid lesions as compared to that of formalin. Fifty-one unselected consecutive cases of thyroid nodules, which included various benign and malignant lesions, were examined. Each specimen was cut in two equal parts; one was fixed in LNRS, the other in formalin. Fixation in LNRS for 2 hours gave adequate results in sectioning and staining of the tissue, and excellent immunostains. Its advantage over formalin is the conservation of the natural relationship between the capsule and the rest of the tissue, on the same plane, as well as the short time required for the final diagnosis. (+info)
Characterization of socio-psychological stress-induced antinociception in the formalin test in mice.
The antinociceptive effect induced by exposure to socio-psychological (PSY) stress using a communication box was assessed by the formalin test in mice, compared with those by exposure to footshock (FS) stress and forced swimming (SW) stress. After the termination of stress exposure, whereas exposure to FS- and SW-stress resulted in the attenuation of the formalin-induced biphasic pain response over 15 min, no appreciable antinociceptive effect was found in the case of PSY stress. When exposure to PSY stress was started during the period of early or late phase of pain after the formalin injection, the antinociceptive effect was maintained for 5-15 min; however, further exposure to PSY stress was not effective for producing antinociception. In the tail-pinch test, likewise, exposure to PSY stress longer than 5 min rather decreased the intensity of antinociception. We conclude that PSY stress in this tonic pain paradigm produces antinociception, but further continuous exposure to the emotional stress caused mice to become recuperative even in such a fear-inducing situation. (+info)
Immunofluorescence detection of ezrin/radixin/moesin (ERM) proteins with their carboxyl-terminal threonine phosphorylated in cultured cells and tissues.
Ezrin/radixin/moesin (ERM) proteins are thought to play an important role in organizing cortical actin-based cytoskeletons through cross-linkage of actin filaments with integral membrane proteins. Recent in vitro biochemical studies have revealed that ERM proteins phosphorylated on their COOH-terminal threonine residue (CPERMs) are active in their cross-linking activity, but this has not yet been evaluated in vivo. To immunofluorescently visualize CPERMs in cultured cells as well as tissues using a mAb specific for CPERMs, we developed a new fixation protocol using trichloroacetic acid (TCA) as a fixative. Immunoblotting analyses in combination with immunofluorescence microscopy showed that TCA effectively inactivated soluble phosphatases, which maintained the phosphorylation level of CPERMs during sample processing for immunofluorescence staining. Immunofluorescence microscopy with TCA-fixed samples revealed that CPERMs were exclusively associated with plasma membranes in a variety of cells and tissues, whereas total ERM proteins were distributed in both the cytoplasm and plasma membranes. Furthermore, the amounts of CPERMs were shown to be regulated in a cell and tissue type-dependent manner. These findings favored the notion that phosphorylation of the COOH-terminal threonine plays a key role in the regulation of the cross-linking activity of ERM proteins in vivo. (+info)
Antinociceptive properties of the new alkaloid, cis-8, 10-di-N-propyllobelidiol hydrochloride dihydrate isolated from Siphocampylus verticillatus: evidence for the mechanism of action.
The antinociceptive action of the alkaloid cis-8, 10-di-n-propyllobelidiol hydrochloride dehydrate (DPHD), isolated from Siphocampylus verticillatus, given i.p., p.o., i.t., or i.c.v., was assessed in chemical and thermal models of nociception in mice, such as acetic acid-induced abdominal constriction, formalin- and capsaicin-induced licking, and hot-plate and tail-flick tests. DPHD given by i.p., p.o., i.t., or i.c.v. elicited significant and dose-related antinociception. At the ID50 level, DPHD was about 2- to 39-fold more potent than aspirin and dipyrone, but it was about 14- to 119-fold less potent than morphine. Its analgesic action was reversed by treatment of animals with p-chlorophenylalanine, naloxone, cyprodime, naltrindole, nor-binaltrorphimine, L-arginine, or pertussis toxin. Its action was also modulated by adrenal-gland hormones but was not affected by gamma-aminobutyric acid type A or type B antagonist, bicuculine, or phaclofen, nor was it affected by glibenclamide. DPHD, given daily for up to 7 days, did not develop tolerance to itself nor did it induce cross-tolerance to morphine. However, animals rendered tolerant to morphine presented cross-tolerance to DPHD. The antinociception of DPHD was not secondary to its anti-inflammatory effect, nor was it associated with nonspecific effects such as muscle relaxation or sedation. DPHD, in contrast to morphine, did not decrease charcoal meal transit in mice, nor did it inhibit electrical field stimulation of the guinea pig ileum or mouse vas deferens in vitro. Thus, DPHD produces dose-dependent and pronounced systemic, spinal, and supraspinal antinociception in mice, including against the neurogenic nociception induced by formalin and capsaicin. Its antinociceptive effect involves multiple mechanisms of action, namely interaction with mu, delta, or kappa opioid systems, L-arginine-nitric oxide and serotonin pathways, activation of Gi protein sensitive to pertussis toxin, and modulation by endogenous glucocorticoids. (+info)
Vaccination with experimental feline immunodeficiency virus vaccines, based on autologous infected cells, elicits enhancement of homologous challenge infection.
Cats were vaccinated with fixed autologous feline immunodeficiency virus (FIV)-infected cells in order to present viral proteins to the immune system of individual cats in an MHC-matched fashion. Upon vaccination, a humoral response against Gag was induced. Furthermore, virus-neutralizing antibodies were detected in a Crandell feline kidney cell-based neutralization assay, but not in a neutralization assay based on primary peripheral blood mononuclear cells. Despite the induction of these FIV-specific responses, vaccinated cats were not protected. Instead, accelerated virus replication was found, an observation similar to what previous experiments using other vaccine candidates have shown. Here, the results of the present study are discussed in the light of enhancement of lentivirus infections as a complicating factor in lentivirus vaccine development. (+info)
Halothane effect on formalin-induced paw edema and flinching in rat.
The formalin test is a model of injury-produced inflammatory pain. Anesthetics, in clinically relevant concentrations, affect neutrophils and immune suppression. This study was to determine whether halothane reliably inhibits inflammatory reaction and formalin induced pain behavior or does not. Rats were exposed to 100% oxygen (control) or halothane, respectively for 30 min and then 24 hr later five percent formalin test was assessed. The base values of the paw's diameter were obtained earlier, and then formalin induced edema was assessed by measuring diameters of the injected paws at 5 min, 1 hr, 4 hr and 24 hr after the injection. Nociceptive behavior was quantified by counting the number of times with the paw flinched at 5 min intervals for 60 min. The diameters of edema in the halothane group lessened more than those in the oxygen group at 1 and 24 hr in each following of the injection (p<0.05). The rats pre-administered with oxygen or halothane were similar appearances in nociceptive behaviors. It suggests that halothane anesthesia might inhibit slightly the inflammatory reaction with the formalin-induced edema but might not inhibit the formalin-induced pain behavior in the event of pre-administration halothane 24 hr earlier before the formalin test of rat. (+info)