Effects of external calcium, magnesium, and temperature on spontaneous contractions of pregnant human myometrium

Spontaneous isometric contractions of small isolated segments from the isthmic region of pregnant human myometrium were recorded to clarify the characteristics of and influences of experimental conditions on contractions. There is a spontaneous periodicity in membrane activity of human myometrium, and contractions evoked with a sustained electric stimulus were affected by spontaneous rhythmic contractions. The frequency of contractions increased markedly, but their duration decreased when temperature of the bathing fluid was increased from 26 degrees C to 39 degrees C. Both excess (7 mM) and low (0.5 mM) calcium levels suppressed the generation of spontaneous contraction. Frequency and half-duration gradually decreased when external magnesium was increased from 0 mM to 3.6 mM. These results indicate that the pattern of contraction depends on the frequency of and intervals between each action potential, and that spontaneous contractility-particularly its frequency-is extremely sensitive to external temperature and ionic conditions.     

Edible oil degradation by using yeast coculture of <Emphasis Type="Italic">Rhodotorula pacifica</Emphasis> ST3411 and <Emphasis Type="Italic">Cryptococcus laurentii</Emphasis> ST3412

To develop a microbial treatment of edible oil-contaminated wastewater, microorganisms capable of rapidly degrading edible oil were screened. The screening study yielded a yeast coculture comprising Rhodotorula pacifica strain ST3411 and Cryptococcus laurentii strain ST3412. The coculture was able to degrade efficiently even at low contents of nitrogen ([NH₄–N] = 240 mg/L) and phosphorus sources ([PO₄–P] = 90 mg/L). The 24-h degradation rate of 3,000 ppm mixed oils (salad oil/lard/beef tallow, 1:1 w/w) at 20°C was 39.8% ± 9.9% (means ± standard deviations of eight replicates). The highest degradation rate was observed at 20°C and pH 8. In a scaled-up experiment, the salad oil was rapidly degraded by the coculture from 671 ± 52.0 to 143 ± 96.7 ppm in 24 h, and the degradation rate was 79.4% ± 13.8% (means ± standard deviations of three replicates). In addition, a repetitive degradation was observed with the cell growth by only pH adjustment without addition of the cells.     

Characteristics of β-adrenergic receptors in longitudinal muscle membranes of rat uterus: Changes in kinetic properties of the receptor during gestation

Binding characteristics of β-adrenergic receptors of longitudinal muscle membranes isolated from different stages of pregnant rat myometrium were investigated using [³H]dihydroalprenolol. Between Days 15 and 21 of gestation, the ratio of β₁- and β₂-adrenergic receptors of longitudinal membranes was constant. The membranes were found to be predominant in β₂-adrenergic receptors. The concentration of longitudinal muscle β-adrenergic receptors increased significantly during the last 7 days of gestation. Kinetic binding studies implied that the affinity of the membrane β-adrenergic receptors decreased through a slight decrease in the association rate and a large increase in the dissociation rate with progression of pregnancy. A Scatchard plot indicated that longitudinal muscle in β-adrenergic receptors on Days 15 and 18 constitute a single class of independent sites. By contrast, the dissociation kinetics, the convex downward curvature in a Scatchard plot and a Hill coefficient (h) of less than 1.00 of [³H] DHA binding to β-receptors of muscle on Day 21 suggested the existence of negatively cooperative multiple binding sites for β-adrenergic ligand. These results suggest that changes in the dynamics of uterus β-adrenergic receptors play an important role in the onset of labor.     

Age-Related Ischemia in the Brain Following Bilateral Carotid Artery Occlusion—Collateral Blood Flow and Brain Metabolism

Cerebral blood flow (CBF) and cerebellar blood flow (CeBF) were measured and correlated with brain lactate, pyruvate and adenosine triphosphate concentrations from groups representing 3-week old suckling (n = 10), 18–22-week old adult (n = 9) and 70-week old aged (n = 7) Sprague-Dawley rats before and during bilateral carotid occlusion (BCO). The steal ratio, calculated as the ratio of %control CBF to %control CeBF, was 1.02 ± 0.06 (mean ± SEM) at 60 minutes of BCO in adult rats that exhibited normal levels of brain metabolites. By contrast, the ratios significantly decreased to 0.74 ± 0.06 in suckling rats and 0.69 ± 0.06 in aged rats with simultaneous increases by 2.4 to 2.9-fold of tissue lactate. Pyruvate and lactate/pyruvate ratio also increased by 1.4 to 1.8 times control in both suckling and aged rats. We conclude that there is age-related steal phenomenon occurring with blood flow during BCO. Ischemic derangement of the brain metabolism is in part related to poor blood supply from the posterior circulation in suckling and aged rats.     

Purification and properties of N-acetylneuraminate lyase from Escherichia coli

N-Acetylneuraminate lyase [N-acetylneuraminic acid aldolase EC 4.1.3.3] from Escherichia coli was purified by protamine sulfate treatment, fractionation with ammonium sulfate, column chromatography on DEAE-Sephacel, gel filtration on Ultrogel AcA 44, and preparative polyacrylamide gel electrophoresis. The purified enzyme preparation was homogeneous on analytical polyacrylamide gel electrophoresis, and was free from contaminating enzymes including NADH oxidase and NADH dehydrogenase. The enzyme catalyzed the cleavage of N-acetylneuraminic acid to N-acetylmannosamine and pyruvate in a reversible reaction. Both cleavage and synthesis of N-acetylneuraminic acid had the same pH optimum around 7.7. The enzyme was stable between pH 6.0 to 9.0, and was thermostable up to 60 degrees C. The thermal stability increased up to 75 degrees C in the presence of pyruvate. No metal ion was required for the enzyme activity, but heavy metal ions such as Ag+ and Hg2+ were potent inhibitors. Oxidizing agents such as N-bromosuccinimide, iodine, and hydrogen peroxide, and SH-inhibitors such as p-chloromercuribenzoic acid and mercuric chloride were also potent inhibitors. The Km values for N-acetylneuraminic acid and N-glycolylneuraminic acid were 3.6 mM and 4.3 mM, respectively. Pyruvate inhibited the cleavage reaction competitively; Ki was calculated to be 1.0 mM. In the condensation reaction, N-acetylglucosamine, N-acetylgalactosamine, glucosamine, and galactosamine could not replace N-acetylmannosamine as substrate, and phosphoenolpyruvate, lactate, beta-hydroxypyruvate, and other pyruvate derivatives could not replace pyruvate as substrate. The molecular weight of the native enzyme was estimated to be 98,000 by gel filtration methods. After denaturation in sodium dodecyl sulfate or in 6 M guanidine-HCl, the molecular weight was reduced to 33,000, indicating the existence of 3 identical subunits. The enzyme could be used for the enzymatic determination of sialic acid; reaction conditions were devised for determining the bound form of sialic acid by coupling neuraminidase from Arthrobacter ureafaciens, lactate dehydrogenase, and NADH.     

Expansion of effector memory regulatory T cells represents a novel prognostic factor in lower risk myelodysplastic syndrome

Myelodysplastic syndromes are premalignant diseases characterized by cytopenias, myeloid dysplasia, immune dysregulation with association to autoimmunity, and variable risk for acute myeloid leukemia transformation. Studies of FOXP3(+) regulatory T cells (Tregs) indicate that the number and/or activation state may influence cancer progression in these patients. Focusing on patients with a lower risk for leukemia transformation, 18 (34.6%) of 52 patients studied displayed an altered Treg compartment compared with age-matched controls. Delineation of unique Treg subsets revealed that an increase in the absolute number of CD4(+)FOXP3(+)CD25(+)CD127(low)CD45RA(-)CD27(-) Tregs (effector memory Tregs [Treg(EM)]) was significantly associated with anemia (p = 0.046), reduced hemoglobin (p = 0.038), and blast counts ≥5% (p = 0.006). In healthy donors, this Treg(EM) population constitutes only 2% of all Tregs (one to six Tregs per microliter) in peripheral blood but, when isolated, exhibit greater suppressive activity in vitro. With a median follow-up of 3.1 y (range 2.7-4.9 y) from sample acquisition, increased numbers of Treg(EM) cells proved to have independent prognostic importance in survival estimates, suggesting that enumeration of this Treg subset may be a more reliable indicator of immunological escape than FOXP3(+) T cells as a whole. Based on multivariate analyses, Treg(EM) impacted survival independently from myeloblast characteristics, cytopenias, karyotype, and comorbidities. Based on these findings, Treg(EM) cell expansion may be synonymous with human Treg activation and indicate microenvironmental changes conducive to transformation in myelodysplastic syndromes.