THE RESPONSE OF MALE GAMETES OF ALLOMYCES TO THE SEXUAL HORMONE SIRENIN

Attraction of male gametes of Allomyces to sirenin concentrations as low as 10^−-10 m has been demonstrated. Increasingly strong responses are observed to concentrations up to 10^−-6 m. The response is slightly weaker at 10^−-5 m and very weak at 10^−-4 m. Microscopic studies suggest that the attraction comes into the category of tropotaxis, a direct approach to a sirenin source occurring. Male gametes have been shown to inactivate sirenin. The possibility that this inactivation is an adaptation process enabling the gametes to maintain sirenin sensitivity over a 100,000-fold concentration range is discussed.     

Myasthenia Gravis: Anesthetic and Surgical Management of the Patient Undergoing Thymectomy

Experience in the anesthetic and surgical management of 25 patients with myasthenia gravis is recorded. These are subdivided into two groups: those operated on during the period 1950-1958 and those operated on during the period 1959-1964. The purpose of this paper is to indicate improvement in mortality and morbidity due to three major advances: (1) use of the decamethonium diagnostic test in a myasthenia gravis clinic; (2) improvements in assessment and management of respiratory insufficiency; and (3) avoidance of anticholinesterase treatment in the immediate and early postoperative recovery period.Fourteen patients with myasthenia gravis, including five with thymoma and two who were refractory to medication, were in the second (1959-1964) group. There were no deaths and no myasthenic or cholinergic crises. Three prophylactic tracheostomies were performed. No emergency bronchoscopies or tracheostomies were required.     

Biomechanical interactions of cancer cells with the microvasculature during metastasis

Metastasis is a major, life-threatening complication of cancer. The bloodstream is the most important disseminative route for cancer cells liberated from their parent tumors. Single circulating cancer cells are arrested in the microvasculature, where the vast majority are killed by rapid or slow processes, and the relatively few survivors grow into micrometastases. We review the underlying causes of one type of rapid cancer cell death in the microcirculation, namely, that caused by biomechanical interactions of cancer cells with microvessel walls, which may result in cell surface membrane expansion and lethal rupture. These lethal interactions appear to be important rate-regulators in hematogenous metastasis, and to dictate some aspects of metastatic patterns. Although these are not the only interactions involving cancer cells, in contrast to others involving cellular and humoral defense mechanisms, they have received comparatively little attention.     

Secretion by human fibroblasts of monocyte chemoattractant protein-1, the product of gene JE

We recently purified human monocyte chemoattractant protein-1 (MCP-1) from culture fluids of either human glioma cell lines or mitogen-stimulated human peripheral blood mononuclear leukocytes. It has now been shown that MCP-1 is the product of the gene JE, which was first recognized by its expression in fibroblasts stimulated with platelet-derived growth factor (PDGF). We therefore studied secretion of MCP-1 by three human fibroblast cell lines. Monocyte chemotactic activity was found in culture fluids of all three lines after growth to confluence in DMEM-10% FCS, and the amounts secreted per cell were comparable for the three lines. The MRC-5 line was chosen for further study. Monocyte chemotactic activity secretion by confluent MRC-5 cultures continued after a switch to serum-free medium and was not inhibited by anti-PDGF antibody, indicating that secretion may not have been caused by autocrine release of PDGF. When concentrated serum-free MRC-5 culture fluid was injected into an HPLC gel filtration column, only one chemotactic activity peak was observed, which was in the same location as glioma-derived MCP-1. The activity was completely absorbed out by an anti-MCP-1 affinity column, which indicates that all the chemotactic activity in MRC-5 culture fluid was accounted for by MCP-1. PDGF caused a marked increase in chemotactic activity over that found in serum-free culture fluid of MRC-5 or 501T cells. Immunoprecipitation by anti-human MCP-1 showed two bands, corresponding to the two forms of MCP-1 previously described (MCP-1 alpha and beta); and the amounts increased in response to PDGF stimulation. Thus, the reported increase in human fibroblast JE mRNA in response to PDGF-containing serum stimulation is reflected in increased secretion of the MCP-1 gene product.     

Identification of high affinity receptors for human monocyte chemoattractant protein-1 on human monocytes

The binding of human monocyte chemoattractant protein-1 (MCP-1) to human monocytes was studied. MCP-1 was radioiodinated with Iodo-beads (Pierce Chemical Co., Rockford, IL) without significant loss of biologic activity. 125I-MCP-1 binding to PBMC occurred within 5 min at 0 degrees C and the binding was inhibited by unlabeled MCP-1 dose dependently but not by neutrophil attractant/activation protein-1 or FMLP. 125I-MCP-1 bound to monocytes; no significant binding to either neutrophils or lymphocytes was observed. Scatchard plot analysis indicated that monocytes had a minimum of 1700 +/- 600 binding sites per cell with a Kd of 1.9 +/- 0.2 x 10(-9) M. For analysis of binding by flow cytometry, MCP-1 was biotinylated. In contrast to radioiodination, biotinylation resulted in loss of activity; potency was 10-fold less, but the efficacy was retained. Detection by flow cytometry of bound biotinylated MCP-1 with avidin-FITC confirmed results obtained with 125I-MCP-1. Biotinylated MCP-1 bound to monocytes but not to lymphocytes; and the binding was inhibited by a 100-fold excess of unlabeled MCP-1.     

Leukocyte specificity and binding of human neutrophil attractant/activation protein-1

Neutrophil attractant/activation protein-1 (NAP-1) was previously shown to attract human neutrophils, but not monocytes. The purpose of this study was to determine if NAP-1 interacted with other types of blood leukocytes. In addition to its chemotactic activity for neutrophils, NAP-1 induced chemotactic responses by T lymphocytes and basophils. Chemotactic potency (10(-8) M for an optimal response) was the same for all three cell types. However, NAP-1 caused a chemotactic response in excess of random migration of 7% or 16% of basophils (depending on the medium used) and only 9% of T lymphocytes, in contrast to 30% of neutrophils. This agonist was not chemotactic for partially purified normal human eosinophils. The symmetrical histogram obtained by flow cytometry of neutrophils equilibrated at 0 degree C with fluoresceinated NAP-1 indicates that all neutrophils bound the ligand. A dose-response curve plateau, and inhibition of binding of NAP-1-FITC by unlabeled ligand are evidence for saturable binding to receptors, estimated to be 7000 per cell. Our results suggest that, for induction of an acute inflammatory response, the quantitatively significant action of NAP-1 is on neutrophils.     

Influence of pH on the conformation and stability of mismatch base-pairs in DNA

A series of self-complementary dodecanucleotide duplexes containing two symmetrically disposed mismatches have been studied by pH-dependent, ultraviolet light melting techniques. The results indicate that A.C, and C.C mismatches are strongly stabilized by protonation and that the degree of stabilization of the A.C mismatch depends greatly on the flanking bases. In one case, a duplex containing two A.C mismatches is more stable than the native sequence below pH 5.5. The G.A mismatch displays conformational flexibility, with a protonated G(syn).A(anti) base-pair occurring in certain base stacking environments but not in others. The A.A and T.C mismatches are not stabilized at low pH. These solution studies correlate well with predictions based on X-ray crystallographic data.     

Brain and Plasma Quinolinic Acid in Profound Insulin-Induced Hypoglycemia

Profound insulin-induced hypoglycemia is associated with early-onset neuronal damage that resembles excitotoxic lesions and is attenuated in severity by antagonists of N-methyl-D-aspartate receptors. Hypoglycemia increases L-tryptophan concentrations in brain and could increase the concentration of the L-tryptophan metabolite quinolinic acid (QUIN), an agonist of N-methyl-D-aspartate receptors and an excitotoxin in brain. Therefore, we investigated the effects of 40 min of profound hypoglycemia (isoelectric EEG) and 1-2 h of normoglycemic recovery on the concentrations of QUIN in brain tissue, brain extracellular fluid, and plasma in male Wistar rats. Plasma QUIN increased 6.5-fold by the time of isoelectricity (2 h after insulin administration). Regional brain QUIN concentrations increased two- to threefold during hypoglycemia and increased a further two- to threefold during recovery. However, no change in extracellular fluid QUIN concentrations in hippocampus occurred during hypoglycemia or recovery as measured using in vivo microdialysis. Therefore, the increases in brain tissue QUIN concentrations may reflect elevations of QUIN in the intracellular space or be secondary to the increases in QUIN in the vascular compartment in brain per se. L-Tryptophan concentrations increased more than twofold during recovery only. Serotonin decreased greater than 50% throughout the brain during hypoglycemia, while 5-hydroxyindoleacetic acid concentrations increased more than twofold during hypoglycemia and recovery. In striatum, dopamine was decreased 75% during hypoglycemia but returned to control values during recovery, while striatal 3,4-dihydroxyphenylacetic acid and homovanillic acid were increased more than twofold during both hypoglycemia and recovery.(ABSTRACT TRUNCATED AT 250 WORDS)