Comparison of hen egg lysozyme immunoassays based on different labels

To check the concentrations of hen egg lysozyme in foodstuffs, added as a bacteriostatic agent, immunoassays based on different labels have been developed. The following detection limits (defined as non‐specific binding increased by three standard deviations) were achieved using antibody labelled with either peroxidase ¹²⁵ I or a biotin‐streptavidin system: 0–8; 0–75 and 0–13 ng/ml, respectively. Only the most sensitive lysozyme immunoassay was likely to be suitable for application to analysis of cheese because matrix interference effects mean that sample extracts need to be diluted prior to assay.     

In vitro activation of cyclo-oxygenase in the rabbit carotid body: effect of its blockade on [3H]catecholamine release.

The release of prostaglandin E2 (PGE2) from rabbit carotid bodies (CBs) incubated in basal conditions (PO2 approximately 132 mmHg; PCO2 approximately 33 mmHg; pH = 7.42) amounts to 94.4 +/- 10.1 pg (mg protein)-1 (10 min)-1 (mean +/- S.E.M.). Incubation of the CB in a hypoxic solution (PO2 approximately 46 mmHg) produced a significant 40% increase (P < 0.05) in the release of PGE2. Indomethacin (2 microM) prevented the hypoxia-induced release of PGE2. Sensory plus sympathetic denervation of the CB 4 days prior to the experiments did not modify either basal or low PO2-induced PGE2 release, indicating that intraglomic nerve endings are not significant sources for the PGE2 released. Incubation of the CB in an acidic-hypercapnic solution (PO2 approximately 132 mmHg; PCO2 approximately 132 mmHg; pH = 6.60) or in a high K(+)-containing solution (35 mM) was also effective in promoting an increase in the outflow of PGE2 from the organs. The release of [3H]catecholamines ([3H]CA) from the CB elicited by incubating the organs in low PO2 solutions (PO2 ranged between 66 and 13 mmHg) was potentiated by two inhibitors of cyclo-oxygenase, acetylsalicylic acid (ASA, 100 microM) and indomethacin (2 microM). The effect persisted after chronic denervation of the organ. The secretory response elicited by acidic stimuli was also augmented by cyclo-oxygenase inhibitors. Thus, [3H]CA release elicited by incubating the CBs in the acidic-hypercapnic solution increased by 300% in the presence of indomethacin (2 microM), and ASA (100 microM) more than doubled the release induced by dinitrophenol (100 microM), a protonophore that mimics an acidic stimulus. Indomethacin, but not ASA, moderately increased the high K(+)-evoked [3H]CA release. The effect of indomethacin on the release of [3H]CA elicited by acidic and hypoxic stimuli was reversed by PGE2 in a dose-dependent manner (0.3-300 nM). These results show that low PO2 and high PCO2-low pH, the natural stimuli to the CB, as well as high extracellular [K+], activate the cyclo-oxygenase pathway in the CB, promoting an increase in the outflow of PGE2. The data also show that the blockade of this pathway activates the stimulus-induced [3H]CA release from the CB, indicating that naturally released prostanoids exert an inhibitory control on chemoreceptor cells. The data lend support to the notion that the hyper-reactivity of the ventilatory response to hypoxia in subjects under anti-inflammatory drug treatment results from CB cycloxygenase inhibition.     

Spleen abscess caused byEikenella corrodens

A case is reported of splenic abscess due toEikenella corrodens, a gram-negative rod which is found as part of normal flora in human mucous surfaces. A 64-year-old man presented with fever, chills, anorexia and abdominal pain. Abdominal ultrasound examination showed a perisplenic fluid collection which was considered to be either blood or a subcapsular spleen abscess. The presence of a splenic abscess was later confirmed during surgery and a splenectomy was performed. Splenic purulent material and blood cultures yieldedEikenella corrodens. The patient received cefotaxime for 19 days and was discharged asymptomatic.     

Mobility and symmetry in the Fc and pFc' fragments as probed by 1H NMR

The 270 MHz ¹H NMR spectra of rabbit Fc and pFc′ fragments appear well resolved when compared to the spectra of other proteins of similar molecular weight. This is interpreted as evidence for substantial segmental flexibility in these fragments. This mobility can be monitored using two special NMR pulse sequences which exploit either the multiplet structure (spin coupling) or the differential linewidths of resonances. Several aromatic residues with mobility independent of the rest of the protein could be detected by these techniques.The titration behaviour of the histidine residues of pFc′ indicates that this fragment possesses a longitudinal C-2 symmetry axis. Of the three pairs of histidines in pFc′, two titrate with pK_a values of 6.8 and 7.3, while the remaining pair remains protonated over the pH range 5.2–8.2 suggesting that these residues are not readily accessible to the solvent. The observation of five pairs of histidine C-2 proton resonances in the Fc indicates that the symmetry axis is retained in this larger fragment.Cleavage of the inter-heavy chain disulphide bond in the Fc fragment has little effect on its NMR spectrum. We find from this that the reduction in complement binding efficiency associated with this cleavage is not a direct consequence of a concomitant large structural change in the Fc fragment.     

Contraction history affects the in vivo quadriceps torque-velocity relationship in humans

We hypothesized that the history of contraction would affect the in vivo quadriceps torque-velocity relationship. We examined the quadriceps torque-velocity relationship of the human knee extensors at the descending and ascending limb of the torque-position relationship by initiating the knee extension at a knee angle position of 1.39 rad (80°) or 0.87 rad (50°) over a 0.52 rad (30°) range of motion under conditions of constant or linearly increasing velocity. Maximal voluntary isometric knee extension torque (M₀) was measured at 1.87 rad, 0.87 rad, and 0.35 rad, and concentric torque was measured. The subjects carried out ten maximal knee extensions at ten distinct velocities, each velocity ranging between 0.52 rad·s^–1 to 5.24 rad·s^–1 in steps of 0.52 rad·s^–1. Peak concentric torque was measured and mean torque calculated from the respective torque-time curves. Peak or mean torque, computed from the individual torque-time curves, and velocity data were fitted to the Hill equation under the four experimental conditions and the curve parameters computed. The M₀ was similar at 0.87 rad and 1.39 rad, but it was significantly lower at 0.35 rad. In the low-velocity domain of the torque-velocity curve where a plateau normally occurs, peak torque was always lower than M₀. Peak and mean torque were significantly greater under linearly increasing velocity conditions and the 1.39 rad starting knee position. Mean torque but not peak torque data could be well fitted to the Hill equation and the two computations resulted in significantly different Hill curve parameters including the concavity ratio, peak power, and maximal angular velocity. We concluded that the history of contraction significantly modifies the in vivo torque-velocity relationship of the human quadriceps muscle. Muscle mechanics and not neural factors may have accounted for the inconsistencies in the human torque-velocity relationships reported previously. Electronic Publication     

Beta-alanine potentiation of [3H]flunitrazepam binding to rat spinal cord homogenates

The effect of beta-alanine, gamma-aminobutyric acid (GABA), and other functionally related amino acids on [3H]flunitrazepam binding to rat spinal cord homogenates was studied. beta-Alanine potentiated [3H]flunitrazepam binding by 40% and GABA by 88%. Taurine increased the binding by 19%. Hypotaurine produced an 11% increase. No significant effect was seen in glycine, alanine, serine, valine or the dipeptide carnosine. The beta-alanine increase in [3H]flunitrazepam binding was completely inhibited by 10 microM strychnine, whereas the GABA increase required 0.1 mM strychnine to be fully suppressed. Results suggest that beta-alanine specifically potentiates binding of [3H]flunitrazepam in rat spinal cord homogenates.     

Lactosamine type asialooligosaccharide recognition in NK cytotoxicity

Inhibition of pig NK cell activity by asialooligosaccharides (aOS) isolated from human serum glycoproteins was investigated. Train-tennary aOS (aOSIII) of ceruloplasmin was found to be the most potent inhibitor up to the concentration 0.1 micrograms/ml, which is in agreement with its highly specific binding to NK-activity-enriched pig lymphocytes (with a morphology similar to human large granular lymphocytes (LGL]. Only lectins with the specificity to Gal(beta 1----4)GlcNAc or Gal(beta 1----3)GalNAc structures exhibited inhibition of NK cytotoxicity. F(ab)2 fragments of rabbit antibodies against pig spleen membrane lectin cross-reacting with the pig liver membrane lectin completely inhibited NK activity when preincubated with the effectors or present in the incubation mixture during the assay. These data suggest that lectin receptors on cells of pig NK-activity-enriched fraction specific for aOSIII and antigenically related to membrane lectins isolated from pig spleen and liver, are involved in the NK recognition of several xenogeneic targets.     

Preparation trauma in stomatology

In this paper authors deal with the causes of preparation trauma in stomatology. They have studied effects of high temperature on human cells cultured in vitro. Based both on literature data and on their own experience they summarize basic principles of preparation which prevent preparation trauma. They summarize how to eliminate as much as possible factors that damage hard dental tissues and pulp.     

Interruption of pregnancy by cervical rivanol predilatation

Experience obtained in 1361 cases of first trimester pregnancy interruption with cervical Rivanol predilatation is reported. Rivanol-induced predilatation of the cervical canal prior to interruption was found to be an efficient procedure. The dilating effect of Rivanol could not be enhanced by i.m. administration of 5 IU oxytocin. After the interruption of more advanced pregnancies a higher degree of dilatation of the cervix was observed. The necessity of further dilatation prior to vacuum aspiration is, in the majority of cases, not higher than 2-2.5 H, which is insignificant on the softened cervix. The immediate complications of medical induction and interruption were infrequent and not severe. Thus, cervical predilatation with Rivanol prior to vacuum aspiration is a recommendable method of pregnancy interruption, worthy of widespread application.     

Antigenic homogeneity among the adenovirus hexon types of subgenus C

Summary Antigenic relationships of hexons of human adenovirus (Ad h) types 1, 2, 5 and 6 of subgenus C were studied with 61 monoclonal antibodies (MAbs) raised against human Ad h1, Ad h35 and bovine adenovirus 2. The reactivity pattern (RP) and the titers of the MAbs were determined in indirect ELISA. In previous experiments with hexons of different subgenera 49 MAbs displayed numerous different intertype specificities besides genus specific and type specific ones. With the four hexon types of subgenus C all MAbs gave identical RPs except the type specific ones. Data reveal the existence of a remarkable homogeneity in the antigenic structure among the hexon types of subgenus C defined by the presence of identical or closely related intertype specific epitopes on the surface of the hexons. The possible significance of the results in the experimental gene therapy is discussed.