Platelet-activating factor acetylhydrolase in term and preterm human milk: a preliminary report

Human milk may protect against necrotizing enterocolitis (NEC). Since platelet-activating factor (PAF) may participate in the pathophysiology of NEC, we measured PAF acetylhydrolase (PAF-AH), which metabolizes PAF, in term and preterm human milk. The activity of PAF-AH in term milk collected 2-4 days after delivery (n = 17) was 2.7 +/- 1.2 nmol x min-1 x ml-1. A higher activity was found in milk collected at similar times from mothers who delivered between 33 and 36 weeks of gestation (n = 6, 5.6 +/- 2.1 nmol x min-1 x ml-1, p < 0.01). However, milk from mothers who delivered between 26 and 32 weeks of gestation had a PAF-AH activity similar to that of term milk (n = 6, 3.0 +/- 0.7 nmol x min-1 x ml-1). With advancing lactational age, PAF-AH activity in term milk decreased, whereas the activity of this enzyme in preterm milk remained unchanged. In milk samples collected beyond 14 days after delivery from women who gave birth between 33 and 36 weeks or 26 and 32 weeks of gestation, PAF-AH activity was fivefold higher than that found in milk for women delivering at term (3.7 +/- 1.3 and 3.6 +/- 3.6 nmol x min-1 x ml-1 serum 0.7 +/- 0.4 nmol x min-1 x ml-1, respectively, p < 0.05). We speculate that the presence of PAF-AH in human milk may protect against NEC in preterm newborns.

Functional morphological alterations of human blood platelets induced by oxidized low density lipoprotein

The effect of oxidized low density lipoprotein (LDL) on the functional morphology of human platelets in vitro was studied by means of transmission electron microscopy. The washed platelets, stimulated by oxidized LDL (50-300 micrograms protein/ml), showed disc-sphere transformation, centralization of granules and complete degranulation in a dose- and time-dependent manner. A cytodamage in platelet membrane was induced by oxidized LDL leading to a lower electron density of cytoplasm compared to control. The morphological observations were supported by an analysis of the platelet shape-change parameter. Since the shape change, induced by oxidized LDL (50 micrograms/ml), was inhibited by a preincubation of platelets with staurosporine (10 nM), the protein kinase C was probably involved in the platelet activation initiated by oxidized LDL. The present results suggest that oxidized LDL could contribute to pathological thrombosis and atherogenesis by activating platelets.

Platelet activating factor-acetylhydrolase activity following chorionic villus sampling and amniocentesis

OBJECTIVE

Platelet activating factor (PAF) is essential for embryonic development and is a potent vasodilator. It increases vascular permeability and stimulates prostaglandin E2 (PGE2) production. Platelet activating factor-acetylhydrolase (PAF-AH), the enzyme that degrades PAF, is synthesized by decidual macrophages. The aim of this study was to test the hypothesis that chorionic villus sampling (CVS) and/or amniocentesis might cause an increase in maternal PAF-AH activity.

METHODS

Maternal plasma PAF-AH activity was evaluated before and after genetic amniocentesis (N = 13) and transcervical CVS (N = 29). A control group (N = 9) was evaluated to study the effects of venipuncture.

RESULTS

Chorionic villus sampling caused a significant elevation in PAF-AH activity (P < .0005). No changes were noted in PAF-AH activity in the amniocentesis or the control group.

CONCLUSIONS

Chorionic villus sampling causes subclinical release of PAF-AH, possibly from the decidual macrophages. Increased PAF-AH activity might result in decreased PAF levels, which might lead to vasoconstriction in the placental circulation due to lack of the vasodilator effects of PAF and possibly PGE2. This mechanism might explain the increased risk for fetal limb reduction noted with CVS performed at very early gestational ages.

Brain abscess due to Pasteurella multocida

The patient was a 26-year-old man who complained of headache and vomiting. On examination, there was nothing abnormal, but the edge of the right optic papilla was not clear. His temperature was 38.5 degrees C, pulse 96/min, blood pressure 120/80 mmHg. A space-occupying lesion in his fronto-dextra cupular part was found by CT scanning. He had a 12-year history of chronic purulent otitis. The diagnosis was a brain abscess in the fronto-dextra cupular part. The brain abscess was extracted and Pasteurella multocida was isolated from the dark brown pus draining from the abscess. The patient recovered through proper antibiotic therapy based on a sensitivity test. Reports of infections caused by this organism in foreign countries very widely from local infections due to bites and scratches by cats, dogs etc. to general infections such as infections of the respiratory tract, sepsis and meningitis. However, Pasteurella multocida brain abscesses are rare. Pasteurella multocida is a Gram-negative short rod which is best known as part of the mouth flora and as a pathogen causing septicemia in many domestic animals, such as cats, dogs etc.. Infection in man results mainly from animal bites or scratches. It has been reported that Pasteurella multodida can cause human septicemia, meningitis, respiratory tract infection, conjunctivitis and other infections. We isolated a strain of Pasteurella multocida from the pus of a brain abscess following chronic purulent otitis on August 6, 1990.

[Clinical study of the treatment of fallopian tube obstruction with catheter recanalization and blood stasis removing drugs]

50 patients with fallopian tube obstruction were initially treated by catheter recanalization, and then randomly divided into two groups. Chinese medicine group (CMG) treated with Tongjingbao and Angelicae Complex Injection and Western medicine (Gentamycin, Dexamethasone, Chymotrypsin) group (WMG) as a control. The course of treatment was three months. Before and after treatment, the hemorheology change was analysed. After treatment, all patients except subsequent pregnancy were repeatedly performing hysterosalpingography. The results showed effective rate of recanalization was 94%; corrected pregnancy rate was 100% in CMG and 50% in WMG; the reocclusion rate of fallopian tube was 9% in CMG and 25% in WMG (P < 0.05). The difference of hemorheology change between two groups was significant (P < 0.01) and it was also different before and after treatment in CMG (P < 0.01). This study showed that catheter recanalization was effective in recanalizing the mechanical occluded fallopian tube. The Chinese medicine would inhibit the reocclusion and re-adhesion of tube.

Some humoral factors and their interaction on acute hypoxic pulmonary pressor response

To determine the effect of humoral factors and their interaction on the development of acute hypoxic pulmonary pressor response (HPPR), we performed studies in 16 mongrel dogs. We measured plasma levels of noradrenaline (NE), angiotensin II (AII), prostaglandin F2 alpha (PGF2 alpha), 6-keto-prostaglandin F1 alpha (6KPGF1 alpha), thromboxane B2 (TXB2), leukotriene B4 (LTB4) and 5-hydroxytryptamine (5-HT) before, during and after HPPR. Multiple regression analysis showed that the changes of pulmonary arterial systolic pressure (PASP) and pulmonary arterial diastolic pressure (PADP) correlated well with those of plasma concentration of NE, PGF2 alpha and 6KPGF1 alpha, respectively (r were equal to 0.633 and 0.668, respectively, P < 0.01). The results of orthogonal experiment analysis with an injection of exogenous NE, PGF2 alpha and PGI alpha into main pulmonary artery of dogs showed that NE and the interaction of PGF2 alpha and PGI2 alpha increased PASP (P < 0.05) and PGI2 attenuated PASP (P < 0.01). The interaction of PGF2 alpha and PGI2 and of PGF2 alpha and NE increased PADP(P < 0.01) and PGI2 attenuated PADP (P < 0.01).

In vivo EPR studies of the metabolic fate of nitrosobenzene in the mouse

We report the first demonstration of EPR spectroscopy to study free radical reactions in live mice and excised muscle tissue resulting from the metabolism of nitrosobenzene. A broad three-line EPR spectrum (aN = 11.6 G) appeared in the buttocks region of a mouse place in an L-band loop gap resonator after intramuscular or intraperitoneal injection of 0.2 mmol/kg nitrosobenzene. The signal intensity reached a maximum at 20 to 30 min and remained constant well beyond 2 h. If muscle tissue was dosed with nitrosobenzene and excised within 5 min, a similar three-line X-band EPR spectrum was obtained which was preceded by the rapid growth and subsequent decay of an EPR spectrum identical with that of the phenylhydronitroxide radical, which was presumably generated from reactions between nitrosobenzene and reducing agents in the blood or tissue such as NADH or ascorbic acid. A model system containing nitrosobenzene and unsaturated fatty acids (olive oil or animal fat) yielded an identical three-line spectrum resulting from radical adducts of nitrosobenzene across the double bond. Overall, these results suggest that the most probable mechanism in vivo was nitrosobenzene covalently adding ("binding") to polyunsaturated fatty acid clusters in fat or membranes.

Three-dimensional structure of a simian immunodeficiency virus protease/inhibitor complex. Implications for the design of human immunodeficiency virus type 1 and 2 protease inhibitors

Simian immunodeficiency virus (SIV) proteins have considerable amino acid sequence homology to those from human immunodeficiency virus (HIV); thus monkeys are considered useful models for the preclinical evaluation of acquired immune deficiency syndrome (AIDS) therapeutics. We have crystallized and determined the three-dimensional structure of SIV protease bound to the hydroxyethylene isostere inhibitor SKF107457. Crystals of the complex were grown from 25-32% saturated sodium chloride, by the hanging drop method of vapor diffusion. They belong to the orthorhombic space group I222, with a = 46.3 A, b = 101.5 A, and c = 118.8 A. The structure has been determined at 2.5-A resolution by molecular replacement and refined to a crystallographic discrepancy factor, R (= sigma parallel Fo magnitude of - magnitude of Fc parallel/sigma magnitude of Fo magnitude of), of 0.189. The overall structure of the complex is very similar to previously reported structures of HIV-1 protease bound to inhibitors. The inhibitor is bound in a conformation that is almost identical to that found for the same inhibitor bound to HIV-1 protease, except for an overall translation of the inhibitor, varying along the backbone atoms from about 1.0 A at the termini to about 0.5 A around the scissile bond surrogate. The structures of the SIV and HIV-1 proteins vary significantly only in three surface loops composed of amino acids 15-20, 34-45, and 65-70. Superposition of the 1188 protein backbone atoms from the two structures gives an rms deviation of 1.0 A; this number is reduced to 0.6 A when atoms from the three surface loops are eliminated from the rms calculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of low density lipoproteins on cytosolic free Ca2+ concentration and dense tubular system in human platelets

The cytosolic free Ca2+ concentration [Ca2+]i and dense tubular system (DTS) of washed human platelets were affected by low density lipoproteins (LDL) of 25 micrograms/ml at 37 degrees C for 10 minutes. After the incubation with LDL, the [Ca2+]i increased from 115 +/- 29 nM to 141 +/- 24 nM. LDL promoted the increase of [Ca2+]i (471 +/- 31 nM) induced by thrombin (0.03 U/ml) as compared to that which thrombin did alone (240 +/- 11 nM) (p < 0.05). The increased Ca2+ influx from the extracellular space is thought to be the reason of the increase in [Ca2+]i, since the effect of LDL was abolished by removal of external Ca2+ by EGTA. The DTS changed primarily from thin elongated forms to rounded vesicles. No evidence was noticed that LDL caused a mobilization of Ca2+ from the DTS.

[Study on the induction of active immunity in human by injecting human anti-HBs antibodies]

One hundred and three health volunteers were injected with various doses of human anti-HBs (Ab1). The anti-idotypic antibodies (Ab2) and anti-antiidiotypic antibodies (Ab)3 in sera were tested at intervals of 30 days with ELISA. We found that the dynamic changes between Ab2 and Ab3 of immune sera were cyclical by way of their interaction and the Ag-specific Ab3 were the same as Ab1 in specificity. The results reconfirmed that exogenous human anti-HBs could induce active immunity by activation of idiotypic network and regulation in human body suggesting that injection of Ig into body could bring about not only passive immunity but also active immunity.

Inhibition of human immunodeficiency virus-1 protease by a C2-symmetric phosphinate. Synthesis and crystallographic analysis

The human immunodeficiency virus type 1 (HIV-1) protease is a potential target of acquired immune deficiency syndrome (AIDS) therapy. A highly potent, perfectly symmetrical phosphinate inhibitor of this enzyme, SB204144, has been synthesized. It is a competitive inhibitor of HIV-1 protease, with an apparent inhibition constant of 2.8 nM at pH 6.0. The three-dimensional structure of SB204144 bound to the enzyme has been determined at 2.3-A resolution by X-ray diffraction techniques and refined to a crystallographic discrepancy factor, R (= sigma parallel F(o) magnitude to - Fc parallel/sigma magnitude of F(o)), of 0.178. The inhibitor is held in the enzyme active site by a set of hydrophobic and hydrophilic interactions, including an interaction between Arg8 and the center of the terminal benzene rings of the inhibitor. The phosphinate establishes a novel interaction with the two catalytic aspartates; each oxygen of the central phosphinic acid moiety interacts with a single oxygen of one aspartic acid, establishing a very short (2.2-2.4 A) oxygen-oxygen contact. As with the structures of penicillopepsin bound to phosphinate and phosphonate inhibitors [Fraser, M. E., Strynadka, N. C., Bartlett, P. A., Hanson, J. E., & James, M. N. (1992) Biochemistry 31, 5201-14], we interpret this short distance and the stereochemical environment of each pair of oxygens in terms of a hydrogen bond that has a symmetric single-well potential energy curve with the proton located midway between the two atoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet-activating factor in surfactant preparations

Surfactant administration is used for treatment of neonatal respiratory distress syndrome. We studied whether currently used surfactant preparations contain platelet-activating factor (PAF), a potent lipid mediator produced by fetal lungs. Three surfactant preparations from animal sources contained between 36 and 218 pmol of PAF per mL, whereas PAF was undetectable in an artificial surfactant. Based on current recommendations, about 144-654 pmol PAF would be administered per dose of natural surfactant, sufficient to exert possible physiological effects on the lung. The action of PAF may be exacerbated by low activity of PAF-acetylhydrolase, which inactivates PAF, in tracheal fluid from infants with respiratory distress syndrome.

RRR-alpha-tocopheryl succinate inhibits proliferation and enhances secretion of transforming growth factor-beta (TGF-beta) by human breast cancer cells

The RRR-alpha-tocopheryl succinate form of vitamin E inhibits the proliferation of estrogen receptor-positive and estrogen receptor-negative human breast cancer cell lines in a dose-dependent manner in vitro. Analyses of cell-conditioned medium from RRR-alpha-tocopheryl succinate growth-inhibited cells revealed the presence of a potent antiproliferative activity. Characterization of the antiproliferative activity as transforming growth factor-beta (TGF-beta) was established by 1) growth inhibition of the TGF-beta-responsive Mv1Lu-CCL-64 mink lung and murine CTLL-2 cell lines, 2) combination of physical characteristics including heat stability, acid stability, and Bio-Gel P-60 column chromatography elution profile, and 3) neutralization of the antiproliferative activity in the conditioned media by antibodies specific for TGF-beta.

Cytokinetic studies on the aortic endothelium and limb bud vascularization in avian embryos

Cytokinetic studies on the aortic endothelium using the BrdU/anti-BrdU-method were carried out on 2.5- to 6-day chick and quail embryos. The mitotic activity of the aortic endothelium is related temporally to the age of the avian embryo and spatially to the embryonic region where the aorta originates. The mitotic activity of the aortic endothelium decreases with increasing age of the embryos. In the limb buds, however, the mitotic rate of the aortic endothelial cells increases independently of the age of the embryo. This increase in the mitotic activity of the aortic endothelium at the appropriate levels coincides with the vascularization of the outgrowing limb buds. We concluded therefore that the aortic endothelium probably supplies endothelial cells for the formation of limb vessels at this stage. Thus our results suggest that angiogenesis (sprouting of capillaries from pre-existing vessels) takes place during limb vascularization in avian embryos. On the other hand, immunohistochemical studies with QH-1 or MB-1 antibody show, beside a capillary network in the central core of the wing bud, individual immunolabelled cells of mesenchymal character within the primarily avascular subectodermal region from the onset of vascularization onwards. We suggest that these cells have partly to be regarded as endothelial precursor cells, which have differentiated in situ from the local limb mesenchyme, and which will contribute to the developing vascular plexus. This means that not only angiogenesis, but also vasculogenesis (in situ from mesenchymal precursors differentiated endothelial cells) appears to be involved in limb vessel formation.

Ultrastructure of the spermatid and spermatozoon of Macracanthorhynchus hirudinaceus

The ultrastructure of the spermatid and spermatozoon of Macracanthorhynchus hirudinaceus (Archiacanthocephala) was studied by means of transmission electron microscopy. The flagellum and nucleus in the spermatid gradually expanded simultaneously. The karyoplasma of the spermatid transformed into dense inclusions and a multibarrel structure, which were also found in the spermatozoan body. The multibarrel structure was located close to the flagellum and consisted of many irregular microtubes. The flagellum of the developing spermatozoon was observed in a concavity of the spermatid nucleus. The microtubule arrangement of the flagellum was "9 + 2". No mitochondria or acrosome were observed in spermatozoa.

Structure of scorpion toxin variant-3 at 1.2 A resolution

The crystal structure of the variant-3 protein neurotoxin from the scorpion Centruroides sculpturatus Ewing has been refined at 1.2 A resolution using restrained least-squares. The final model includes 492 non-hydrogen protein atoms, 453 protein hydrogen atoms, eight 2-methyl-2,4-pentanediol (MPD) solvent atoms, and 125 water oxygen atoms. The variant-3 protein model geometry deviates from ideal bond lengths by 0.024 A and from ideal angles by 3.6 degrees. The crystallographic R-factor for structure factors calculated from the final model is 0.192 for 17,706 unique reflections between 10.0 to 1.2 A. A comparison between the models of the initial 1.8 A and the 1.2 A refinement shows a new arrangement of the previously poorly defined residues 31 to 34. Multiple conformations are observed for four cysteine residues and an MPD oxygen atom. The electron density indicates that disulfide bonds between Cys12 and Cys65 and between Cys29 and Cys48 have two distinct side-chain conformations. A molecule of MPD bridges neighboring protein molecules in the crystal lattice, and both MPD enantiomers are present in the crystal. A total of 125 water molecules per molecule of protein are included in the final model with B-values ranging from 11 to 52 A2 and occupancies from unity down to 0.4. Comparisons between the 1.2 A and 1.8 A models, including the bound water structure and crystal packing contacts, are emphasized.

Prevention of the spread of HIV-1 infection with nonnucleoside reverse transcriptase inhibitors

Certain bisheteroarylpiperazines (BHAPs) directly inhibit the replication of human immunodeficiency virus type 1 (HIV-1) and block the spread of infection to susceptible populations of cells. At a 1 microM concentration three analogs, U-87201, U-88204, and U-89674, inhibited the replication of HIV-1 in MT-2 cells by 83, 100, and 93%, respectively. At the same concentration, U-88204 completely inhibited replication of primary HIV-1 isolates in peripheral blood mononuclear cells. Replication of 3'-azido-2',3'-dideoxythymidine (AZT)-resistant strains of HIV-1 was also inhibited by U-88204. When MT-2 cells that were lytically infected with HIV-1 were mixed with uninfected MT-2 cells, U-88204 provided complete protection to the uninfected cells. Integrated proviral DNA sequences were not detected by the polymerase chain reaction technique in this culture after 15 days in the presence of drug. The resultant healthy cell culture was subsequently maintained without drug with no evidence of latent proviral DNA. Serial passage of a laboratory strain and a primary isolate of HIV-1 in cell culture in the presence of increasing concentrations of U-88204 yielded virus populations which were at least 100-fold resistant to the drug. These resistant viruses also showed cross-resistance to the pyridinone class of nonnucleoside inhibitors but were sensitive to AZT. Analysis of the nucleotide sequence of resistant viruses revealed mutations at conserved regions of the reverse transcriptase (RT) gene. The results presented here suggest the therapeutic potential of U-88204 in the combination therapy for HIV-1 infection.

Electron spin resonance determination and superoxide dismutase activity in polymorphonuclear leukocytes in congestive heart failure

Electron spin resonance spin trapping technique was used to measure the generation of active oxygen free radicals during the respiratory burst of phorbol myristate acetate-stimulated leukocytes, and the superoxide dismutase activity in healthy subjects and in patients with congestive heart failure. The authors also measured the concentration of peroxidation products (primarily malondialdehyde) by the thiobarbituric acid method. Experimental results showed that the electron spin resonance spectra obtained during the respiratory burst of polymorphonuclear leukocytes stimulated with phorbol myristate acetate primarily were those of the spin adduct of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) with the superoxide anion and to a lesser extent those of DMPO with hydroxyl radical. Compared with healthy subjects, the release of oxygen free radicals in the respiratory burst of polymorphonuclear leukocytes stimulated with phorbol myristate acetate and the concentration of thiobarbituric acid reactive product in plasma were significantly increased in patients with congestive heart failure while the activity of superoxide dismutase was markedly lower. The increased production of oxygen free radicals by polymorphonuclear leukocytes and the decreased capability of antioxidative defences might play an important role in the generation and development of cardiac failure.

The human gene for apurinic/apyrimidinic endonuclease (HAP1): sequence and localization to chromosome 14 band q12

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