Up-regulation of neutral endopeptidase (CALLA) in human neutrophils by granulocyte-macrophage colony-stimulating factor

Neutral endopeptidase 24.11 (NEP/CALLA/CD10), an enzyme expressed on early lymphoid progenitors, neutrophils, and various other cell types, inactivates many biologically active peptides, including the bacterial chemotactic peptide N-formylmethionyl-leucyl-phenylalanine (fMLP). Inhibition of CD10/NEP on the surface of human neutrophils (PMNs) in vitro inhibits migration toward this chemotaxin, suggesting that enzymatic inactivation by NEP regulates the neutrophil response to fMLP. Because PMNs in inflammatory sites are exposed to various cytokines, we evaluated the effects of selected cytokines on CD10/NEP activity in vitro. Of five cytokines tested--interleukin-1 (IL-1), IL-6, and IL-8, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor (GM-CSF)--GM-CSF provided the most consistent increase in surface NEP activity. Low concentrations (10(-9)-10(-7) M) of GM-CSF increased NEP activity in a time- and concentration-dependent manner to more than 225% that of control (phosphate-buffered saline-treated) cells. Cytofluorometry of cells stained with a fluorescent antibody to CD10 indicated that GM-CSF increased expression of surface CD10/NEP antigen in a similar manner. The effect of GM-CSF on NEP activity was enhanced still further by simultaneous exposure to IL-1, suggesting that combinations of cytokines may direct and regulate the neutrophil response within an inflammatory site. Rapid upregulation of CD10/NEP underscores the importance of this enzyme for control of peptide mediators of inflammation.

Mechanisms of fibrin formation and lysis by human lung fibroblasts: influence of TGF-beta and TNF-alpha

Fibrin gels form within the alveolar and interstitial compartments of the injured lung, and fibroblasts invade and facilitate organization of these transitional gels. We studied the effects of transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha) on fibrinolytic and procoagulant activities of human lung fibroblasts (HLF) to determine their capacity to regulate pulmonary fibrin deposition. Fibrinolytic activity of cell lysates and media (n = 6 HLF cultures) were uniformly depressed by TGF-beta or TNF-alpha. In dose and time-course studies, HLF plasminogen activator inhibitor-1 (PAI-1) was increased by TGF-beta, whereas TNF-alpha induced release of PAI-1 into the media. HLF and media urokinase concentrations were depressed by TGF-beta, whereas urokinase was unchanged or increased by TNF-alpha. Tissue plasminogen activator was mainly cell associated and unchanged by TGF-beta or TNF-alpha. HLF antiplasmin activity was not detected. Plasma recalcification times of HLF media were decreased by TNF-alpha but unchanged by TGF-beta. These studies suggest that TGF-beta and TNF-alpha impair the ability of HLF to degrade fibrin by disturbing the balance of HLF plasminogen activators and PAI and that these cytokines concurrently leave unchanged or increase the capacity of HLF to initiate fibrin formation. Cytokines likely to occur in the injured lung induce abnormalities of fibrinolysis in HLF from adults; such abnormalities favor extravascular fibrin deposition, a characteristic feature of alveolitis.

Pathways of fibrin turnover of human pleural mesothelial cells in vitro

The mesothelium contains both procoagulant and fibrinolytic activities. An imbalance between these activities could account for the abnormal fibrin turnover and pleural fibrin deposition that is characteristic of pleural inflammation. Procoagulant activity of human pleural mesothelial cells (HPMC) is in part due to tissue factor, and the prothrombinase complex can also assemble at the HPMC surface. HPMC express tissue plasminogen activator (tPA) but no detectable fibrinolytic activity in a fibrin plate assay. Inhibition of HPMC fibrinolytic activity is due, in part, to elaboration of plasminogen activator inhibitors-1 and -2 (PAI-1 and PAI-2) as well as antiplasmins. Synthesis of PAI-1 and PAI-2 is inhibited by actinomycin D and cyclohexamide. HPMC PAI-1 is increased by transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha), as is tPA release, while PAI-1 mRNA is unchanged and tPA mRNA is increased. PAI-2 release is induced by TNF-alpha and TGF-beta. Because they are a rich source of PAI-1 and PAI-2, HPMC may contribute to the high levels of these inhibitors in pleural exudates. Stimulation of HPMC by TNF-alpha or TGF-beta in vitro did not alter HPMC procoagulant activity nor the balance of elevated PAI and antiplasmins relative to PA, changes that collectively favor formation and persistence of pericellular fibrin.

Interaction of Pseudomonas aeruginosa with human lung fibroblasts: role of bacterial elastase

Colonization of cell surfaces by Pseudomonas aeruginosa is mediated by bacterial adherence, which, in turn, is influenced by both host and microbial factors. Previous studies with this organism suggest that elastase contributes to tissue invasion and necrosis. We studied the effects of Pseudomonas elastase (PE) on the adherence of P. aeruginosa to human lung fibroblast monolayers. Treatment of fibroblasts with PE (1 microgram/ml or 0.06 U/ml) increased adherence of 35S-labeled P. aeruginosa to cells, but heat-inactivated PE did not affect bacterial adhesion. Immunocytochemistry of cultured cells showed that PE (0.06 to 0.63 U/ml) decreased fibronectin (Fn) on the cell surface and extracellular matrix of cultured human lung fibroblasts. Data obtained by cytofluorography indicated that elastase also decreased Fn receptors on fibroblasts. Additional evidence for Fn degradation was provided by SDS-PAGE analysis of soluble Fn and proteins from surface iodinated cell monolayers treated with PE. We conclude that the increased bacterial adherence to fibroblasts may be due, in part, to elastase-induced proteolysis of Fn and its receptors on cell surfaces. Degradation of Fn could thus influence the extent and course of Pseudomonas infection in the lungs.

Is routine endocrine testing of impotent men necessary?

Endocrine screening of impotent men is performed in an effort to identify a treatable cause of impotence. However, the prevalence of endocrinopathy in this patient population is low. We determined whether any historical or physical findings obtained during the initial office visit would identify a subgroup of patients at risk for endocrinopathy to decrease the cost of endocrine screening. The results of routine endocrine screening of 330 consecutive impotent patients formed the basis of this study. A total of 7 patients (2.1%) had endocrinopathy. Testicular atrophy was observed in 5 of these 7 patients and 6 reported decreased libido. All of the patients with endocrinopathy had either decreased libido or bilateral testicular atrophy. Our results indicate that the cost of impotence evaluation can be decreased by screening only those patients with clinical signs of hypogonadism, that is either decreased libido or bilateral testicular atrophy.

Chemical sensitivity in physicians

By the nature of their work environment, physicians may be exposed to potentially toxic substances that can trigger chemical sensitivity. Nineteen physicians with chemical sensitivity were evaluated at the Environmental Health Center - Dallas regarding: type of specialty, history of chemical exposure, symptoms produced, food and water tolerance, immune parameters and double-blind chemical inhalation challenge. Food and chemical sensitivities were demonstrated in these physicians by oral, intradermal and inhalation challenges. After treatment, fifteen of the nineteen physicians were able to resume medical practice. Potential sources of chemical exposure in medical environments are evaluated.

Confirmation of chemical sensitivity by means of double-blind inhalant challenge of toxic volatile chemicals

Fifty chemically sensitive patients with vascular, asthmatic and arthritic signs, ranging in age from 21 to 61, were exposed to double-blind challenges of ambient doses of inhaled toxic chemicals in a specially designed booth in an Environmental Control Unit (ECU). Primary signs and symptoms were recorded before and after challenge with five chemicals and three placebos. Inhaled challenges included phenol (less than .0025 ppm), petroleum-derived ethyl alcohol (less than .5 ppm), formaldehyde (less than .2 ppm), chlorine (less than .3 ppm), and pesticide (2, 3,-D at less than .0034 ppm). Placebos were water or saline. A set on testing criteria were evaluated for maximizing the likelihood of well-defined, reproducible information from these ambient-dose double-blind challenges. For best results, these testing criteria include: Before testing, the patient must be housed in a chemically less polluted environment. The individual must have been de-adapted to food, air, and water pollutants by means of a water fat for three to four days. At the time of the challenge, the patient must be on food and water previously determined to be safe. An enclosed non-pulluted challenge booth must be used for these chemical exposures. Sign and symptom scores appropriate for that patient must be recorded, before and after challenge. Appropriate doses of the chemical in question (determined by air concentration and length of exposure) are necessary to investigate a particular problem. The conclusion of the study is that in these patients, chemical sensitivity clearly does exist (pulse rate differences between positive responses and placebo - p .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aliphatic hydrocarbon solvents in chemically sensitive patients

The purpose of the present study was to see if chemically sensitive individuals had aliphatic hydrocarbon solvents as part of their total body load. This was done by measuring blood levels from 85 chemically sensitive patients. These were measured by a purging trap method with gas chromatography/mass spectrometry (GCC/MS) by the methods of Laseter. Thirteen patients had blood levels below the detection limit of less than 1 ppb and 72 were above the detection limit. An average of three solvents, out of seven measured, including n-pentane, 2,2-dimethylbutane, cyclopentane, 2-methylpentane, 3-methylpentane, n-hexane, n-heptane, was found in 85% of the patients' blood on the 1 to 299 ppb range. The means were as follows: n-pentane 14.7 ppb, 2,2-dimethylbutane 2.5 ppb, cyclopentane 9.0 ppb, 2-methylpentane 16.7 ppb, 3-methylpentane 28.0 ppb, n-heptane 5.5 ppb. The most frequently found of the above solvents was 2-methylpentane (found in 68.1% of the patients), 3-methylpentane (62.5%), n-hexane (61.1%), and pentane (40.3%).

Clearing of toxic volatile hydrocarbons from humans

In this study, different modes of therapy for the removal of toxic chemicals from the human body have been assessed and compared. This consisted of: 1) thirteen inpatients in an environmentally controlled area in a hospital, 2) fourty-one outpatients with home environmental control and work area change, and 3) fifteen outpatients in a physical therapy/sauna program with a good environmental control. Attention to manipulation of food, food contaminants, water and air pollution as well as nutritional therapy was important in all groups. Each modality seemed efficacious in++ its own right; 100% inpatients, 80% sauna/physical therapy patients, and 70% outpatients improved their signs and symptoms. Inpatient therapy in a finally controlled environment was far superior to the other two modalities in clearing of symptoms, as well as in clearing of organic chemicals. Outpatient and sauna/physical therapy are efficacious for less ill patients.

Differential effects of laminin and merosin on neurite outgrowth by developing retinal ganglion cells

In previous work, we showed that cultured avian embryonic retinal ganglion cells (RGC) extend neurites on EHS-laminin early in development, but lose this ability with maturation, as a result of a sharp decline in laminin receptor numbers. Here we show that EHS-laminin promotes neurite outgrowth also from embryonic mammalian RGC, in contrast to previous reports, and that these exhibit similar age-dependent growth responses on laminin. Antibody blocking studies show that this behaviour is mediated in mouse RGC by alpha 6 beta 1 integrin dimers. The laminin isoform merosin is also effective as a neurite outgrowth-promoting substrate for RGC but differs in its ability to elicit a response at advanced stages of development (up to hatching in the chick). Neurite outgrowth by RGC on merosin is inhibited, at all ages, by the function-blocking, anti-beta 1 integrin antibody, CSAT, suggesting that these neurons use alternative alpha beta 1 dimers in their interactions with EHS-laminin and merosin. Together, these findings emphasise the generality of the responsiveness of vertebrate embryonic RGC to laminin during development, and reveal interesting differences in the effects of laminin variants on CNS axon growth and regeneration.

Blood constituents during the estrous cycle and early pregnancy in dairy cows

The objective of this study was to determine if maternal platelet count, white blood cell count or other blood constituents undergo sustained alterations in concentration following fertilization. Blood samples from 17 Holstein females were collected over an 18-d period starting at estrus. Blood was analyzed for levels of platelets, white blood cells, red blood cells, hemoglobin and hematocrit. Results were analyzed for differences between nonpregnant and pregnant groups. Analysis of variance revealed a day-by-group interaction in the platelet count (P<0.01). White blood cell count showed both a day-by-group interaction and a difference between days (P<0.01). Red blood cell count, hematocrit and hemoglobin levels resulted in no significant difference between the two groups (P>0.05). While statistically significant differences were observed in platelet and white blood cell count, neither of these were sustained over a period longer than 2 d.

The effects of embryonic retinal neurons on neural crest cell differentiation into Schwann cells

Amongst the many cell types that differentiate from migratory neural crest cells are the Schwann cells of the peripheral nervous system. While it has been demonstrated that Schwann cells will not fully differentiate unless in contact with neurons, the factors that cause neural crest cells to enter the differentiative pathway that leads to Schwann cells are unknown. In a previous paper (Development 105: 251, 1989), we have demonstrated that a proportion of morphologically undifferentiated neural crest cells express the Schwann cell markers 217c and NGF receptor, and later, as they acquire the bipolar morphology typical of Schwann cells in culture, express S-100 and laminin. In the present study, we have grown axons from embryonic retina on neural crest cultures to see whether this has an effect on the differentiation of neural crest cells into Schwann cells. After 4 to 6 days of co-culture, many more cells had acquired bipolar morphology and S-100 staining than in controls with no retinal explant, and most of these cells were within 200 microns of an axon, though not necessarily in contact with axons. However, the number of cells expressing the earliest Schwann cell markers 217c and NGF receptor was not affected by the presence of axons. We conclude that axons produce a factor, which is probably diffusible, and which makes immature Schwann cells differentiate. The factor does not, however, influence the entry of neural crest cells into the earliest stages of the Schwann cell differentiative pathway.

Neutral endopeptidase from nuchal ligament of fetal calves

The nuchal ligament of unborn calves contains a neutral endopeptidase that is biochemically and immunologically similar to the neutral endopeptidase (NEP), or enkephalinase, from human kidney. Enzymatic activity was inhibited more than 90% by phosphoramidon (1 microM). The specific activity in membrane fractions, as determined by hydrolysis of the dansylated substrate, DAPGN, was similar in tissue from fetuses of gestational ages ranging from 100 to 280 days. NEP activity in adult ligament tissue, however, was less than 10% of that in fetal tissue. Fibroblasts dissociated from ligament tissue by collagenase displayed less NEP activity than did preparations of intact ligament, and activity was even lower in cultured cells. By contrast, fibroblasts cultured from fetal calf lungs had NEP activity comparable to that in the ligament tissue. When ligament fibroblasts were cultured on subcellular matrices derived from fetal lung fibroblasts the NEP activity increased relative to those cultured on plastic alone. These studies confirm the presence of neutral endopeptidase (NEP) in the nuchal ligament of the fetal calf. The consistent activity through a range of gestational ages and the influence of the subcellular matrix suggest that this enzyme might be involved in growth of the ligament during fetal life.

Determination of genome size of Pseudomonas aeruginosa by PFGE: analysis of restriction fragments

Genomic DNA size was measured in three strains of Pseudomonas aeruginosa, ATCC 29260 (exotoxin A), ATCC 33467 (type I smooth) and ATCC 33468 (type 2 mucoid) by transverse alternating field electrophoresis of restriction fragments. Because of the high (67%) G + C content of Pseudomonas aeruginosa, restriction enzymes that recognize sequences with at least 4 AT base pairs were expected to be rare cutters. Eight enzymes produced fragments greater than 200 kb in size: Dral (TTT/AAA), Asnl (ATT/AAT), Hpal (GTT/AAC), AfIII (C/TTAAG), Xbal (T/CTAGA), Spel (A/CTAGT), Sspl (AAT/ATT) and Ndel (CA/TATG). All eight enzymes recognized one of three rare tetranucleotide sequences, TTAA, CTAG or ATAT. Pseudomonas aeruginosa strain 29260 has a genomic DNA size of 5573 kb. Strains 33467 and 33468 have identical restriction patterns and a possible deletion with a genomic size of 5407 kb.

[A pupillographical study on the presence of organochlorine pesticides in autonomic nerve disturbance]

It is well known that the effect of organophosphate pesticides on the autonomic nervous system is a cholinergic reaction. However no study has been done assessing the effect of organochlorine pesticides on the autonomic nervous system. We evaluated the autonomic nerve function using open-loop pupillography in 20 patients who had exposure to the organochlorine pesticides. Significant differences were seen in pupil area (p less than .006), velocity of both constriction and dilatation (p less than .001), and dilatation time (p less than .02), when compared with 18 normal subjects. Autonomic nerve disturbances were detected in eighteen of 20 patients (90%) by evaluating the pupillary light reflex in each patient. Sympathetic nerve inhibition i.e. sympatholytic pattern, was recognized in ten of 18 patients (55%). Four patients with sympatholytic pattern had a disturbance not only in the sympathetic nerve, but also parasympathetic nerve involvement suggesting pandysautonomia. The residue blood level of the organochlorine pesticides was examined in each patient. A high frequency of the DDE was recognized (85%). It was concluded that the toxicity of the organochlorine pesticide on the autonomic nerve appear as an inhibitory effect on pupil light reflex.

Effects of Pseudomonas aeruginosa elastase on alveolar epithelial permeability in guinea pigs

Elastase-deficient mutants of Pseudomonas aeruginosa are less virulent than the wild type and are easily cleared from the lungs of guinea pigs. The effect of P. aeruginosa elastase on lung epithelium, however, is not yet understood. We addressed the hypothesis that breach of the epithelial barrier by elastase from P. aeruginosa allows invading organisms and toxic substances to penetrate the interstitium. We measured the clearance of aerosolized technetium-labeled albumin (molecular weight, 69,000) from the lungs of anesthetized guinea pigs with the aid of a gamma camera and a dedicated computer. Aerosols of the elastase (0.1 to 5 micrograms) increased the rate of clearance of labeled albumin from the lungs in proportion to the elastase dose. Electron microscopic studies using horseradish peroxidase as a tracer revealed that elastase interrupts intercellular tight junctions of the epithelial lining, thereby increasing the permeability to macromolecules. The amounts of elastase used in this report did not cause interstitial or alveolar edema, as determined by both postmortem extravascular lung water volume measurement and morphological examination. The data indicate that the elastase is a potentially important virulence factor in acute lung infection.

Detection and analysis of neutral endopeptidase from tissues with substrate gel electrophoresis

Neutral endopeptidase from human or bovine tissues retains enzymatic activity following electrophoresis and immobilization in polyacrylamide gels. Infiltration of the gel with a fluorogenic substrate permits identification of the active enzyme by fluorescence associated with a distinct protein band. This technique both separates and identifies the enzymatically active species from a crude cell membrane fraction or from partially purified extracts that contain contaminating proteins. Enzymatic activity is quantitated by photographing the fluorescent bands and scanning the negatives with a laser densitometer. Because as little as 25 ng of enzyme can be detected by this method, it could be used where the amount of material is limited.

Chronic fatigue syndrome

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Regulation of synthesis of prostacyclin and HETEs in human endothelial cells

Human umbilical endothelial cells in culture synthesize prostacyclin (PGI2), 15-hydroxyeicosatetraenoic acid (15-HETE), and 12-hydroxyeicosatetraenoic acid (12-HETE). The synthesis of these eicosanoids was measured by specific radioimmunoassays after stimulation by arachidonic acid, A23187, bradykinin, melittin, or histamine. Under all conditions, the synthesis of PGI2 paralleled and exceeded the synthesis of 15-HETE and 12-HETE. Indomethacin inhibited arachidonic acid-stimulated PGI2 and 15-HETE synthesis but enhanced 12-HETE synthesis. Meclofenamate gave similar qualitative results. Drugs that act as inhibitors of lipoxygenase in some tissues, such as nordihydroguaiaretic acid (NDGA), caffeic acid, esculin, diethylcarbamazine, quercetin, and 5,8,11,14-eicosatetrayenoic acid (ETYA) were nonspecific in their inhibition of PGI2, 12-HETE, and 15-HETE synthesis. For example, NDGA inhibited arachidonic acid-stimulated release with a 50% inhibitory concentration (IC50) of 0.39 microM for PGI2, 0.25 microM for 15-HETE, and 0.10 microM for 12-HETE. These results show that endothelial cells metabolize both endogenous and exogenous arachidonic acid to PGI2, 15-HETE, and 12-HETE. These data also suggest, based on results with inhibitors, that PGI2 and 15-HETE are products of cyclooxygenase, whereas 12-HETE is produced via a different enzymatic pathway, most likely a lipoxygenase pathway.

The conditioning effect of optic nerve injury upon axonal regrowth from adult rat retinal ganglion cells explanted in vitro

An in vitro assay was used to determine the effects of conditioning nerve lesions on the regeneration of adult rat retinal ganglion cell (RGC) axons from retinal explants. Following the conditioning lesion (CL) of unilateral optic nerve transection, maximal regrowth was seen from RGC explanted from ipsilateral retinae 10 days post-CL. Explants from this group initiated axonal regrowth earlier and a greater percentage regrew axons when compared with explants from normal rats. Axonal regrowth from explants of retinae contralateral to CL was also seen earlier than normal. In further experiments, the effects of both exposure of the optic nerve sheath in the orbit and the incision of the dura without injury to optic nerve axons were studied. The conditioning effect of a dural incision was found to be the same as that of optic nerve transection, whilst exposure of the optic nerve sheath had no conditioning effect on RGC axonal regrowth in vitro.

Histamine stimulation of prostaglandin and HETE synthesis in human endothelial cells

Endothelial cells (EC) cultured from human umbilical artery (UA) and vein (UV) metabolized [14C]arachidonic acid to prostaglandins (PGs), monohydroxyeicosatetraenoic acids (HETEs), and epoxyeicosatrienoic acids (EETs). Major radioactive products were identified as 6-keto-PGF1 alpha, PGE2, PGF2 alpha, 12-hydroxy heptadecatrienoic acid, 15-HETE, and 11-HETE. In addition, extracts from UV ECs contained 12-HETE, 5-HETE, 14,15-EET, and 5,6-EET as minor products, whereas extracts from UA ECs contained only 12-HETE as a minor product. UA ECs also produced metabolites comigrating with 14,15-EET, 11,12-EET, 8,9-EET, and 5,6-EET. Histamine increased the release of [14C]PGs and [14C]HETEs from [14C]arachidonic acid-labeled ECs. Indomethacin, aspirin, and nordihydroguauretic acid completely inhibited synthesis of both [14C]PGs and [14C]HETEs from exogenous [14C]arachidonic acid in these cells. Microsomes metabolized [14C]arachidonic acid to the same [14C]PGs and [14C]HETEs as intact cells. Pretreatment of microsomes with indomethacin completely inhibited formation of these products. These data indicate that UA ECs and UV ECs metabolize endogenous and exogenous arachidonic acid to both PGs and HETEs. Also 15-HETE and 11-HETE appear to be synthesized by a microsomal enzyme with the properties of cyclooxygenase.

Function of neutral endopeptidase on the cell membrane of human neutrophils

Intact human neutrophils hydrolyzed N-formyl-Met-Leu-[3H]Phe (fMLP) and released Leu-[3H]Phe, cleaving 45-50% of the peptide within 20 min at 37 degrees C. The dipeptide after its release was then hydrolyzed to free amino acids by a dipeptidase (EC 3.4.13.11). This activity, present in plasma membrane-enriched fractions of neutrophil lysates, was also inhibited over 90% by phosphoramidon, an inhibitor of neutral endopeptidase (NEP, EC 3.4.24.11). Dithiothreitol and EDTA inhibited the activity to a comparable degree, suggesting the requirement for a heavy metal cofactor. Bestatin and amastatin, inhibitors of aminopeptidases (but not human kidney NEP), did not inhibit the rate of fMLP degradation but prevented the production of free phenylalanine and enhanced the accumulation of Leu-Phe. Of other inhibitors, alpha 1-antitrypsin and alpha 2-macroglobulin slightly enhanced the rate of fMLP hydrolysis by neutrophils, and others tested were ineffective. Rabbit antiserum to homogeneous human kidney NEP reacted specifically with a 100-kDa protein present in sodium dodecyl sulfate-solubilized neutrophils. The Mr of this protein was slightly larger than that of the kidney enzyme in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The antiserum incubated with intact cells specifically inhibited the degradation of fMLP over 70%. First, we confirm that NEP present on the plasma membrane cleaves fMLP at the Met-Leu bond; then the dipeptide Leu-Phe is cleaved by a dipeptidase. Finally, inhibition of NEP completely blocks fMLP-mediated chemotaxis. Thus, the enzyme may play an important role in modulating chemotactic responses.

Effect of platelet activating factor on leukocyte-endothelial cell interactions

The proinflammatory effects of platelet activating factor (PAF) that impact upon tissue inflammation were studied in vitro using the adherence of human neutrophils to endothelium and the increase in macromolecule permeability of endothelial monolayers. PAF produced both a time- and dose-dependent increase in neutrophil-endothelial cell adhesion. The adhesion promoting properties observed were primarily due to an effect of PAF on endothelium and not on neutrophils and was independent of endothelial cell cyclooxygenase products. The PAF receptor antagonist kadsurenone inhibited the adhesion response suggesting endothelial surface PAF receptors are involved in these responses. Whereas PAF alone did not alter endothelial cell barrier properties, leukocyte activation (neutrophil and platelets) with PAF produced significant increases in 125I-albumin clearance across endothelial monolayers. These studies suggest that PAF has potent proinflammatory effects and that it can play a significant role in the endothelial response to injury.

Neither laminin nor prior optic nerve section are essential for the regeneration of adult mammalian retinal ganglion cell axons in vitro

Retinal explants obtained from normal adult rats and from operated animals in which the optic nerve had been sectioned 10 days previously were cultured in either serum-containing or serum-free medium on poly-L-lysine and laminin substrata. Regenerating ganglion cell axons growing from these explants have been identified using monoclonal antibodies against Thy-1.1 cell surface glycoprotein and the 200-kDa subunit neurofilament protein. Irrespective of substratum or medium composition, axons regenerated from 28-49% of normal rat retinal explants. This percentage increased to 60-84% of explants from operated rats. There were no significant differences in percentages of explants from normal or operated rats showing neurite outgrowth when substrata of either poly-L-lysine or laminin were compared in serum-free medium. In serum-containing medium the results were less easily interpreted due to the presence of an outgrowth of non-neuronal (glia and mesenchymal) 'flat cells', which served as a preferred axonal substratum in many cases. Thus we show that adult rat retinal ganglion cell axons will regrow in vitro, and that a 'priming' optic nerve section will increase this response. In neither case is the response laminin-dependent.

Cultured bovine coronary arterial endothelial cells synthesize HETEs and prostacyclin

Arachidonic acid metabolism was examined in endothelial cells cultured from bovine coronary arteries. In culture, these cells exhibit specific characteristics of endothelial cells. They form a contact-inhibited monolayer with a cobblestone appearance, contain immunoreactive von Willebrand's factor antigen, and have angiotensin I converting enzyme activity. Prostacyclin was the major prostaglandin synthesized from exogenous and endogenous arachidonic acid in these cells. In addition, exogenous arachidonic acid was metabolized to small amounts of prostaglandin E2 (PGE2) and several relatively nonpolar metabolites including 12-, 15-, and 11-hydroxyeicosatetraenoic acids (12-, 15-, and 11-HETE). Histamine, bradykinin, and thrombin increased PGI2 synthesis in these bovine coronary endothelial cells. Of these agonists, bradykinin was the most potent, increasing basal PGI2 release by fourfold. More vigorous stimulation of the cells with mechanical disruption of the cell monolayer, melittin, or A23187 resulted in release of both PGI2 and PGE2. Pretreatment of cells with exogenous arachidonic acid (10(-5) M) abolished their responsiveness to subsequent stimulation by arachidonic acid or vasoactive agents, but not PGH2. Furthermore, treatment of cells with 15-HPETE (10(-7)-10(-4) M), but not 15-HETE, specifically inhibited basal as well as A23187-stimulated PGI2 release. PGE2 release was increased slightly after 15-HPETE treatment. These studies indicate that bovine coronary endothelial cells can metabolize arachidonic acid to several biologically active products and that PGI2 synthesis by these cells is specifically related to the type of vasoactive agent employed. Both the qualitative pattern and quantity of eicosanoids synthesized by bovine coronary endothelial cells differ substantially from endothelial cells isolated from noncardiac vascular beds.

Prostaglandin synthesis in bovine coronary endothelial cells: comparison with other commonly studied endothelial cells

Comparison of arachidonic acid metabolism by bovine coronary artery endothelial cells, bovine aortic endothelial cells and human umbilical endothelial cells indicated potentially important differences in relative amounts of the different prostaglandins produced. Bovine coronary endothelial cells converted 14C-arachidonic acid to radioactive 6-keto PGF1 alpha (the stable metabolite of PGI2) and to a lesser extent PGE2. Bovine aortic cells synthesized 6-keto PGF1 alpha and 6,15-diketo PGF1 alpha as the major products. PGE2, 6-keto PGE1, PGF2 alpha and PGD2 were minor metabolites. By comparison, endothelial cells isolated from human umbilical artery or vein formed mainly 6-keto PGF1 alpha and substantial amounts of PGF2 alpha, PGE2 and PGD2. Basal concentrations of 6-keto PGF1 alpha were two-fold higher in bovine coronary cells than in bovine aortic endothelial cells, but seven-fold less than in endothelial cells cultured from human umbilical vessels. Histamine, bradykinin and thrombin stimulated PGI2 synthesis in both coronary endothelial cells and human umbilical cells, but only bradykinin stimulated PGI2 synthesis in bovine aortic cells. This comparative study indicates that endothelial cells vary in the metabolites of arachidonic acid that they produce depending upon the vascular origin of the cells. Also, endothelial cells from different vascular beds respond differently to specific vasoactive agents.

Steroid 5 alpha-reductase activity in endothelial cells from human umbilical cord vessels

The metabolism of radiolabeled progesterone and androstenedione was evaluated in endothelial cells from human umbilical cord vein and arteries maintained in culture. The predominant metabolite of progesterone was 5 alpha-pregnane-3,20-dione and that of androstenedione was 5 alpha-androstane-3,17-dione. Thus, the major pathway of progesterone and androstenedione metabolism within these cells is via steroid 5 alpha-reductase. The rate of formation of 5 alpha-pregnane-3,20-dione from progesterone by venous endothelial cells was linear with incubation time up to 4 h and with cell number up to 1.6 X 10(6) cells/ml. The apparent Km of 5 alpha-reductase for progesterone was 0.4 microM; and, the Vmax was 55 pmol 5 alpha-pregnane-3,20-dione formed/mg protein X h. The rate of 5 alpha-androstane-3,17-dione formation from androstenedione also was linear with incubation time up to 4 h. In addition to 5 alpha-androstane-3,17-dione, the metabolism of androstenedione by either venous or arterial cells resulted in the formation of various minor metabolites, including testosterone and 5 alpha-reduced steroids, viz. 5 alpha-dihydrotestosterone, androsterone, isoandrosterone, 5 alpha-androstane-3 alpha, 17 beta-diol, and 5 alpha-androstane-3 beta, 17 beta-diol. Estrogens (i.e. estradiol-17 beta and estrone) were not detected as products of androstenedione metabolism. The formation of these metabolites are indicative that the steroid-metabolizing enzymes present in endothelial cells are: 5 alpha-reductase, 17 beta-hydroxysteroid oxidoreductase, 3 alpha-hydroxysteroid oxidoreductase, and 3 beta-hydroxysteroid oxidoreductase.

Tailgut cyst: diagnosis with CT and sonography

Tailgut cyst is a rare congenital lesion that presents as a presacral mass, found in infancy or persisting undetected into adulthood, and characterized by multiple cysts lined with a gastrointestinal type of epithelium. In a retrospective review of five patients whose ages ranged from 1 month to 42 years--three cases with CT and two with sonograms--tailgut cyst appeared as a complex mass on both procedures, representing its composition of multiple small cysts filled with keratinous material and other debris. Other CT and sonographic features include well-defined borders, and, in one case, presentation as a mass lateral to the midline. CT also shows preservation of adjacent fat planes. Tailgut cyst should be included in the differential diagnosis of a retrorectal mass at any age.

Inhibition of prostaglandin synthesis by glucocorticoids in human endothelial cells

The vasodilator prostaglandins (PGs), prostacyclin (PGI2) and PGE2, may contribute to the inflammatory response. Because glucocorticosteroids reduce inflammation, possibly through inhibition of arachidonic acid release, we examined the influence of dexamethasone on PG formation in cultures of human endothelial cells. Binding of [3H]dexamethasone by intact cells was competed by unlabeled steroids and was half-maximal at 1.2 X 10(-8) M. A cytosolic fraction complexed with [3H]dexamethasone and migrated on sucrose density gradient centrifugation with a sedimentation coefficient of 8S. 3H-steroid binding was diminished by unlabeled steroid. Histamine, bradykinin, and the ionophore, A23187, stimulated release of PGI2 and PGE2 to as much as 25 times basal release. Dexamethasone (10(-11) to 10(-7) M) reduced PG formation in cells that were stimulated by histamine, bradykinin, calcium ionophore, or mechanical agitation. The inhibitory effect required at least 4 h to develop, was maximal at 24 h, and persisted after the steroid was removed. Hydrocortisone and triamcinolone had similar effects but were less potent than dexamethasone. Testosterone and progesterone did not affect PG generation. Both arachidonic acid and PGH2 augmented formation of PGs but were not inhibited by dexamethasone. Cortisol-21-mesylate, an antagonist of glucocorticoid receptors, blocked the effects of dexamethasone on PG formation, as did treatment of the cells with cycloheximide. We conclude that glucocorticoids inhibit PG production in endothelial cells by interaction with specific steroid receptors. The steroid-mediated inhibitory effect occurs at the level of arachidonic acid release and depends upon protein synthesis.

Androstenedione metabolism in human lung fibroblasts

Human lung fibroblasts in culture metabolized [3H]androstenedione to a number of different compounds, including testosterone, 5 alpha-androstanedione, androsterone, 5 alpha-dihydrotestosterone, isoandrosterone, and 5 alpha-androstane-3 alpha,-17 beta-diol. The major products were 5 alpha-androstanedione and testosterone. Estrone, estradiol-17 beta and 5 beta-reduced steroids were not formed. The production rates of testosterone and 5 alpha-androstanedione from [3H]androstenedione by lung fibroblasts were studied both as a function of incubation time and substrate concentration. The rates of formation of testosterone and 5 alpha-androstanedione remained linear with time up to 4 h. The apparent Km of human lung fibroblast 5 alpha-reductase was 1 microM, and that of 17 beta-hydroxysteroid oxidoreductase was 11 microM. The findings of this study suggest that mesenchyma may contribute to the metabolism of androstenedione in human lung tissue.

Specific incorporation of 5-hydroxy-6,8,11,14-eicosatetraenoic acid into phosphatidylcholine in human endothelial cells

The incorporation of hydroxyeicosatetraenoic acids (HETEs) into cellular lipids was studied in cultures of human umbilical vein endothelial cells. 5-[3H]HETE was incorporated into the phospholipids (8%) and neutral lipids (15.5%). The uptake was at half maximum after 15 min and reached a plateau after 1 h. The incorporation occurred mainly into phosphatidylcholine (6.3%) with minimal uptake into phosphatidylserine and phosphatidylinositol (0.6%) or phosphatidylethanolamine (1.2%). There was no uptake of 12-[3H]HETE, 15-[3H]HETE or [3H]leukotriene B4 into phospholipids. Treatment of the phosphatidylcholine fraction with phospholipase A2 released 64% of the 5-[3H]HETE with 26% remaining in the lysophosphatidylcholine fraction. This indicates that the majority of the 5-HETE was in the sn-2 position. Unlabeled 5-HETE and arachidonic acid inhibited the uptake of 5-[3H]HETE into phosphatidylcholine with an ID50 of 2.5 and 1.25 microM, respectively. Stearic acid and 15-HETE were not effective inhibitors. Histamine, which activates phospholipases, increased the uptake of 5-[3H]HETE into phosphatidylcholine by 3-fold. Both 5-[3H]HETE and 12-[3H]HETE were incorporated into the neutral lipids of the cells. Analysis of the neutral lipid fraction revealed that 5-[3H]HETE was incorporated into mono-, di- and triacylglycerols but not cholesterol esters. Incorporation of 5-HETE into cellular lipids reduced histamine- and arachidonic acid-stimulated synthesis of 6-ketoprostaglandin F1 alpha and prostaglandin E2 in a concentration-related manner. Angiotensin I converting enzyme activity was not changed. Thus, 5-HETE is incorporated specifically into phosphatidylcholine and glycerol esters of human endothelial cells and this incorporation inhibits prostaglandin synthesis in these cells.

Adrenal masses differentiated by MR

Magnetic resonance imaging was performed in 30 patients with adrenal masses. The abnormalities included adrenal adenomas (n = 10), carcinomas (n = 2), pheochromocytomas (n = 12), and adrenal metastases (n = 6). By the ratio of the signal intensity of the adrenal mass to that of the liver, adenomas could be distinguished from adrenal metastases, adrenal carcinomas, and pheochromocytomas. Metastases and pheochromocytomas could generally be differentiated.

Human gamma interferon increases the binding of T lymphocytes to endothelial cells

Binding of lymphocytes to human umbilical vein endothelial cells (EC) was quantitated by measuring adhesion of 51Cr labelled lymphocytes to endothelial cell monolayers and rosette formation between lymphocytes and EC in suspension. Mitogen stimulated human peripheral blood mononuclear cell culture supernatants and mixed lymphocyte reaction supernatants enhanced the binding of T lymphocytes to EC monolayers or suspensions preincubated with such supernatants. The active component of these supernatants appeared to be gamma interferon (IFN-gamma) since culture supernatants lost activity after heating at 56 degrees C for 60 min, exposure to pH 2.0 or treatment with anti-IFN-gamma. In addition, purified IFN-gamma increased the binding of T lymphocytes to EC (T-EC). This occurred in a concentration dependent manner when IFN-gamma was preincubated with EC but not with lymphocytes. While the optimum concentration of IFN-gamma was 250 u/ml, a significant enhancement was seen with as little as 10 u/ml. These findings suggest that IFN-gamma may play a part in the emigration of lymphocytes to perivascular chronic inflammatory sites by augmenting the adhesion of lymphocytes to the endothelium of small blood vessels.

Neutral endopeptidase 24.11 in human neutrophils: cleavage of chemotactic peptide

Membrane metallo-endopeptidase (NEP; neutral endopeptidase, kidney-brush-border neutral proteinase, enkephalinase, EC 3.4.24.11) cleaves peptides at the amino side of hydrophobic amino acids. While the enzyme is known to be in organs such as kidney and brain, we found it in human neutrophils. These cells cleaved the NEP substrate glutaryl (Glut)-Ala-Ala-Phe-(4-methoxynaphthylamine) (Glut-Ala-Ala-Phe-MNA) at a rate of 9.5 nmol X hr-1 per 10(6) cells, and phosphoramidon (1 microM) inhibited the hydrolysis by 90%. Intact neutrophils from donors who smoked had NEP activities about twice that of nonsmokers. Subcellular fractionation and sucrose density gradient centrifugation of lysed neutrophils showed that most of the NEP activity was membrane bound. A washed membrane fraction from human neutrophils rapidly cleaved 0.5 mM Glut-Ala-Ala-Phe-MNA (96 nmol X min-1 X mg-1) and the hydrolysis was inhibited by phosphoramidon and by specific antiserum to human renal NEP. The washed membrane fraction also rapidly cleaved 0.1 mM bradykinin (34 nmol X min-1 mg-1) and 0.1 mM fMet-Leu-Phe (49 nmol X min-1 X mg-1). The membrane-bound enzyme cleaved the peptide substrates at the same site as the homogeneous human renal NEP, and phosphoramidon and thiorphan inhibited the hydrolysis. Kinetic studies with pure human renal NEP showed that the chemotactic peptide fMet-Leu-Phe was one of the best biologically active substrates (Km, 59 X 10(-6) M; kcat, 3654 min-1). Immunocytochemistry at the light microscopic level revealed a high concentration of NEP on the cell membrane of neutrophils. This was confirmed with electron microscopy using the immunogold technique on ultrathin cryosections. These studies indicate that NEP in neutrophils may have important functions in inflammation and chemotaxis.

Synthesis of dihomoprostaglandins from adrenic acid (7,10,13,16-docosatetraenoic acid) by human endothelial cells

Human umbilical vein endothelial cells were found to contain adrenic acid (22:4) in their cellular lipids. Since this fatty acid may be metabolized by cyclooxygenase in the kidney, the metabolism of adrenic acid was studied in endothelial cell cultures. [14C]Adrenic acid was metabolized to several more polar metabolites. Two of these metabolites co-migrated on HPLC with 1 alpha,1 beta-dihomo-8-ketoprostaglandin F1 alpha (the metabolite of 1 alpha, 1 beta-dihomoprostaglandin I2) and 1 alpha,1 beta-dihomoprostaglandin E2. Indomethacin (10(-5) M) inhibited the synthesis of these metabolites. When cells were treated with adrenic acid (3 X 10(-5) M), a peak that co-migrated with dihomo-8-ketoprostaglandin F1 alpha was detected by radioimmunoassay using an antiserum directed against 6-ketoprostaglandin F1 alpha. The presence of dihomo-8-ketoprostaglandin F1 alpha was confirmed by gas chromatography-mass spectrometry. Immunoreactive peaks that co-migrated with dihomoprostaglandins E2 and F2 alpha were identified with antisera against prostaglandin E2 and prostaglandin F2 alpha, respectively. [14C]Arachidonic acid was metabolized to [14C]prostaglandin F2 alpha, 6-keto[14C]prostaglandin F1 alpha, and [14C]prostaglandin E2. Similar results were found with unlabelled arachidonic acid using specific antisera. When the two fatty acids were combined, adrenic acid reduced the metabolism of arachidonic acid. The culture media from endothelial cells inhibited thrombin-induced platelet aggregation, an effect blocked by aspirin. The inhibitory activity of the media was enhanced when arachidonic acid was added to the cells, but it was reduced by adrenic acid. Both prostaglandin I2 and dihomoprostaglandin I2 inhibited platelet aggregation, but prostaglandin I2 was 100-times more potent. We conclude that adrenic acid is metabolized in human endothelial cells to 1 alpha, 1 beta-dihomoprostaglandins and can compete with endogenous arachidonic acid for conversion by cyclooxygenase. These findings suggest that adrenic acid may reduce the formation of prostaglandin I2 by the blood vessel.

Distinction between adrenal adenomas and metastases using MR imaging

Magnetic resonance imaging was performed on 12 patients with known neoplastic disease and adrenal masses shown by CT. Three patients with metastases had high signal intensity in the adrenals on T2 weighted spin echo scans (SE 2,500/80) and nine patients with nonfunctioning adenomas had low signal intensity on T2 weighted images. The ability to distinguish metastases from nonhyperfunctioning adrenal adenomas may be of use in the pre-operative evaluation in patients with known carcinoma and incidental adrenal masses.

Neutral metalloendopeptidase in human lung tissue and cultured cells

The distribution of a neutral metalloendopeptidase (NEP), or "enkephalinase," in human lung tissue and cultured cells was compared with that of angiotensin I converting enzyme (ACE). The specific activities of NEP and ACE were measured in homogenates of fetal lung tissue and in isolated airways and pulmonary vessels. NEP activity was highest in airway tissue, and ACE activity was highest in isolated vessels. Human endothelial cells from either umbilical veins or pulmonary arteries had high ACE activity (80 to 90 nmol/h/10(6) cells) but only a trace of NEP activity (0.5 to 0.6 nmol/h/10(6) cells). Fibroblasts cultured from human lungs were low in ACE but richer in NEP than cultured endothelial cells. Fibroblasts from human foreskins or caesarean section skin were the richest source of NEP activity (60 to 80 nmol/h/10(6) cells). Immunohistochemical studies confirmed the biochemical assays. As expected, ACE was localized on the luminal surface of blood vessels, with a distribution similar to that of factor VIII antigen, an endothelial marker. In contrast, NEP was localized within the alveolar septa. Cultured endothelial cells stained only weakly for NEP in contrast to cultured fibroblasts. The location of these 2 enzymes in different cells and the differences in peptide substrate specificity suggests that they act sequentially on circulating peptides or those released within microvascular beds.

Enhancement of the antiaggregatory activity of prostacyclin by propranolol in human platelets

The beta-adrenergic antagonist propranolol has been found to inhibit platelet aggregation. We investigated the possibility that propranolol exerts this action by stimulating the synthesis or enhancing the antiaggregatory activity of prostaglandin (PG) I2. The media from cultures of human endothelial cells inhibited thrombin-induced platelet aggregation, an effect attributed to PGI2 production by the cells. When endothelial cells were incubated with dl- or d-propranolol, the media had two to three times the inhibitory activity of control media. However, this increased activity was not due to increased synthesis of PGI2 because control and propranolol-treated cultures synthesized similar amounts of the PGI2 metabolite, 6-keto-PGF1 alpha. Instead, propranolol enhanced the antiaggregatory activity of PGI2. Propranolol (1 microM) and PGI2 (0.05 nM), when tested separately, inhibited aggregation by 19% and 13%, respectively, whereas the combination inhibited aggregation by 51%. PGI2 inhibited platelet aggregation and thromboxane (Tx) B2 production but stimulated cyclic AMP formation. The adenyl cyclase inhibitor 2',5'-dideoxyadenosine (DDA) had no effect of its own on these parameters, but blocked the actions of PGI2. Propranolol inhibited aggregation and TxB2 synthesis without changing cyclic AMP levels. Unlike PGI2, propranolol's effects were not altered by DDA. While the combination of propranolol and PGI2 inhibited aggregation to a greater extent than either agent alone, this enhanced effect with the combination did not extend to TxB2 or cyclic AMP production. Propranolol, PGI2, and the combination inhibited TxB2 synthesis to a similar extent, and PGI2 produced a similar increase in cyclic AMP in the presence and absence of propranolol. These findings indicate that propranolol and PGI2 inhibit platelet aggregation through cyclic AMP-independent and dependent mechanisms, respectively. While propranolol does not alter the synthesis of PGI2, it enhances the inhibition of aggregation by PGI2, and this may contribute to its antiplatelet effect.

Effect of aging and cold temperature storage of hamster ova as assessed in the sperm penetration assay

The penetration of zona pellucida-free hamster ova by human spermatozoa has been used to quantitate sperm penetration potential. However, since mammalian eggs in vitro have limited viability, the effect of in vitro aging on the ability of hamster ova to be penetrated by human spermatozoa was examined. Zona-free ova maintained at room temperature (25 degrees C) lost their ability to be subsequently penetrated with a half-life of 50.1 +/- 8.8 minutes. This was partly the result of removing the zona pellucida by trypsin digestion, since zona-free oocytes in the presence of trypsin inhibitor or zona pellucida-intact oocytes had half-lives of 99.1 +/- 15.2 and 120.5 +/- 17.4 minutes, respectively. Reduction in penetration rates associated with ovum aging did not appear to be due to loss of viability and could be completely prevented by maintaining the ova on ice (4 degrees C). In the presence of TEST-yolk buffer at 4 degrees C, ova retained (100%) their ability to be penetrated for up to 24 hours and were morphologically indistinguishable from fresh ova. These observations show that ovum aging in vitro at 25 degrees C is much greater than previously anticipated. This may result in artifactually low and variable scores in the penetration bioassay.

Metabolism of androsterone and 5 alpha-androstane-3 alpha,17 beta-diol in human lung tissue and in pulmonary endothelial cells in culture

The metabolism of [3H]androsterone and [3H] 5 alpha-androstane-3 alpha,17 beta-diol ( [3H] 3 alpha-diol) was studied in slices of human lung tissue and cultures of human pulmonary artery endothelial cells. Lung tissue metabolized [3H]androsterone (0.25 microM) to 5 alpha-androstane-3,17-dione (30.3 pmol 100 mg-1 tissue h-1), isoandrosterone (0.7 pmol 100 mg-1 tissue h-1), 5 alpha-dihydrotestosterone (5 alpha-DHT; 0.1 pmol 100 mg-1 tissue h-1), 3 alpha-diol (0.1 pmol 100 mg-1 tissue h-1), and two polar metabolites. Pulmonary arterial endothelial cells produced the same metabolites of [3H]androsterone (0.083 microM), with the exception of the polar compounds [5 alpha-androstane-3,17-dione (1.3 pmol mg-1 protein h-1), isoandrosterone (0.1 pmol mg-1 protein h-1), 5 alpha-DHT (0.2 pmol mg-1 protein h-1), and 3 alpha-diol (0.2 pmol mg-1 protein h-1)]. Thus, the principal metabolite of [3H]androsterone in both lung tissue and endothelial cells was 5 alpha-androstane-3,17-dione. Human lung tissue metabolized [3H]3 alpha-diol (0.28 microM) to 5 alpha-DHT (8.8 pmol 100 mg-1 tissue h-1), androsterone (2.2 pmol 100 mg-1 tissue h-1), 5 alpha-androstane-3,17-dione (0.8 pmol 100 mg-1 tissue h-1), isoandrosterone (0.1 pmol 100 mg-1 tissue h-1), and four polar metabolites (0.2 pmol 100 mg-1 tissue h-1). 5 alpha-DHT was the principal metabolite of [3H]3 alpha-diol within the first hour of incubation, but the concentration of this androgen declined thereafter to 3.6 pmol 100 mg-1 tissue after 4 h of incubation. This decline was correlated with increased 5 alpha-androstane-3,17-dione synthesis (6.7 pmol 100 mg-1 tissue 4 h-1). Androsterone formation from [3H]3 alpha-diol, however, was linear with time of incubation for 4 h (8.9 pmol 100 mg-1 tissue 4 h-1). The formation of these products demonstrates that the principal 5 alpha-reduced-C19-steroid-metabolizing enzymes in human lung are 3 alpha-hydroxysteroid oxidoreductase.

Rapid method for quantitation of androgen binding protein in Sertoli cell cultures and its use for measurement of binding kinetics

The accurate measurement of the kinetics of binding of 5 alpha-dihydrotestosterone to the Sertoli cell specific protein, androgen binding protein (ABP), has been frustrated by the extremely rapid rate of dissociation of the ABP-dihydrotestosterone complex. We describe a rapid and highly sensitive assay suitable for ABP quantitation which utilizes DEAE Bio-Gel and [3H]dihydrotestosterone. The assay has been used to accurately measure the rate of dissociation (8.25 X 10(-4) s-1, t1/2 14 min) and the rate of association (2.04 X 10(5) M s-1) of the binding of [3H]dihydrotestosterone to rat ABP. The ratio of these rate constants is in perfect agreement with the equilibrium dissociation constant determined by Scatchard analysis (4.0 nM). This multipoint assay is extremely rapid such that binding can be measured at equilibrium, it has high precision (coefficient of variation 3%), and is particularly useful at low protein concentrations (50 ng/ml); furthermore, the assay background of nonspecific 3H-binding is extremely low (0.2%). Since at such low protein concentrations a 10 point Scatchard analysis can be performed on 1 ml culture medium containing as little as 3 fmol ABP, the assay is suitable for monitoring changes in ABP secretion resulting from manipulations of cells in culture. The assay which utilizes DEAE Bio-Gel A is compared to five alternative methods: the standard method of steady state gel electrophoresis, Dextran-coated charcoal assay, hydroxylapatite assay, DEAE filter assay, and radioimmunoassay. The DEAE Bio-Gel assay has advantages over all of these alternative methods. In summary, this new assay is particularly useful for monitoring temporal changes in the secretion of ABP, and the method is equally effective in quantitating ABP in rat, rabbit and hamster Sertoli cell cultures.

Hydrolysis of opioid hexapeptides by carboxypeptidase N. Presence of carboxypeptidase in cell membranes

Carboxypeptidase N, purified to homogeneity from human plasma, rapidly hydrolyzed Lys6- or Arg6-enkephalins when measured by high pressure liquid chromatography. Comparison of the kinetics of hydrolysis of the enkephalin hexapeptides and bradykinin by carboxypeptidase N revealed the following values for the Km and kcat: Arg6-Met5-enkephalin, 49 microM, 1024 min-1; Arg6-Leu5-enkephalin, 57 microM, 375 min-1; Lys6-Met5-enkephalin, 216 microM, 6204 min-1; bradykinin, 19 microM, 58 min-1. Thus, while bradykinin had the lowest Km, the specificity constants (kcat/Km) for all the enkephalin hexapeptides were higher than that of bradykinin due to their high turnover numbers. Preincubation of the enzyme with 0.1 mM CoCl2 increased both the kcat and Km of bradykinin and Arg6-Met5-enkephalin. Similar results were obtained when the above experiments were conducted with the active 48,000 dalton subunit of carboxypeptidase N. Basic carboxypeptidase activity was found in the amniotic fluid, in membrane fractions of various human and bovine tissues, and in cultured cells in the following order of decreasing specific activity: human placental microvilli, human kidney, human amniotic fluid, human lung, bovine lung, bovine pulmonary artery, human foreskin fibroblasts, human pulmonary arterial endothelial cells, and human lung fibroblasts. The membrane-bound carboxypeptidase activity had a neutral pH optimum and behaved similarly to plasma carboxypeptidase N in the presence of various inhibitors and activators. It was different from the carboxypeptidase activity in bovine adrenal chromaffin granules which had an acid pH optimum and was inhibited by sulfhydryl reagents. These studies show that human carboxypeptidase N, an enzyme found in high concentration in blood, readily hydrolyzes Arg6- or Lys6-enkephalins. It could thus control the levels of these peptides if they are released into the circulation from the adrenal gland. In addition, a membrane-bound carboxypeptidase N-like enzyme in various tissues may regulate the local levels of biologically active peptides containing C-terminal basic amino acids such as hexapeptide enkephalins, kinins, anaphylatoxins or fibrinopeptides.

Studies on human spermatozoa with round head syndrome

The ability of spermatozoa with round head syndrome to penetrate zona pellucida-free hamster ova and to undergo nuclear decondensation was studied in three infertile patients. Whereas spermatozoa from pregnancy-proven donors bound to hamster ova and achieved a penetration rate of 100%, those with round heads did not bind to or penetrate any ova. While spermatozoa nuclear decondensation occurs after ovum penetration and indicates a positive result, it has now been demonstrated that this phenomenon can also be induced by incubating spermatozoa with crushed hamster ova. In addition, nuclei from normal and round-headed spermatozoa decondense in the presence of these ova to a similar degree. These observations suggest that infertility related to round head sperm morphology is associated with an inability to interact with and penetrate the oolemma, rathern than dysfunctional spermatozoan changes following penetration.

Genetic Adaptation to Elevated Carbon Dioxide Atmospheres by Pseudomonas -Like Bacteria Isolated from Rock Cod ( Sebastes spp.)

The microorganisms on rock cod fillets stored in a modified atmosphere (MA; 80% CO 2 -20% air) at 4°C for 21 days were isolated. Only Lactobacillus sp. (71 to 87%) and tan-colored Pseudomonas sp.-like isolates (TAN isolates) were found. The TAN isolates grew more slowly in MA than in air at 8°C. When TAN isolates were grown in air at 8°C and then transferred to MA at 8°C, there was an initial decline in viable counts for 10 to 30 h followed by exponential growth. During this exponential growth phase in MA, the growth rates of the TAN isolates from MA-stored fish were significantly greater than those of the TAN isolates from fresh fish. When a TAN isolate from fresh fish was grown under MA for 21 days, it then grew as rapidly under MA as isolates from MA-stored fish. These results suggest that the TAN isolates genetically adapt to high levels of CO 2 .

Sinusoidal endothelial cells from normal guinea pig liver: isolation, culture and characterization

Guinea pig nonparenchymal hepatic cells were isolated by enzymatic digestion and subsequent separation on a 17.5% metrizamide gradient. Endothelial cell and Kupffer cell-enriched fractions were separated by centrifugal elutriation. Viability of both cell fractions was approximately 80%. Endothelial cells were cultured on a substratum of guinea pig liver collagen and 1% gelatin (1:1). Freshly isolated and cultured sinusoidal endothelial cells contained Factor VIII R:antigen, angiotensin I converting enzyme activity, and they synthesized prostaglandins characteristic of other endothelial cells. Sieve plates were identified in both freshly isolated and cultured cells. Fresh endothelial cells and Kupffer cells formed Fc receptor-mediated rosettes with IgG-opsonized sheep red blood cells, but cultured endothelial cells did not. Only Kupffer cells demonstrated Fc and C3 receptor-mediated phagocytosis. These methods for isolating and culturing sinusoidal endothelial cells should permit further functional assessment of endothelial cells and their interrelationship with other sinusoidal lining cells.

Enzymes in placental microvilli: angiotensin I converting enzyme, angiotensinase A, carboxypeptidase, and neutral endopeptidase ("enkephalinase")

Microvilli from human placental syncytiotrophoblast are rich in angiotensin I converting enzyme (ACE), aminopeptidase A, a carboxypeptidase N-like enzyme, and a neutral endopeptidase (NEP). The specific activities of these enzymes were enhanced in microvillus-enriched fractions obtained by differential centrifugation: Purified microvilli were isolated in a discontinuous sucrose gradient. The placental microvilli hydrolyzed angiotensin II, vasopressin and oxytocin as shown by high pressure liquid chromatography. The inhibitors, bestatin, phosphoramidon, and o-phenanthroline, established the specificity of the enzymes. Aminopeptidase A (angiotensinase A) cleaved angiotensin II to angiotensin III and Asp1. NEP from placenta and from human kidney hydrolyzed oxytocin at the Pro7-Leu8 bond to yield oxytocin 1-7 and leucyl-glycine amide, but did not hydrolyze vasopressin. Vasopressin was cleaved by aminopeptidases in the placental membranes. On electroblotting placental NEP appeared as a double band with a molecular weight slightly higher than the 90,000 of the purified kidney enzyme. Neuraminidase treatment reduced the molecular weight of the placental enzyme to approximately 90,000, indicating that it contains a large amount of sialic acid. The microvilli of human placenta are thus rich in enzymes that may regulate passage of peptides at the maternal-fetal interface.

Hydrolysis of substance p and neurotensin by converting enzyme and neutral endopeptidase

Angiotensin I converting enzyme (ACE) and neutral endopeptidase ("enkephalinase"; NEP), were purified to homogeneity from human kidney. NEP cleaved substance P (SP) at Gln6-Phe7,-Phe8, and Gly9-Leu10 and neurotensin (NT) at Pro10-Tyr11 and Tyr11-Ile12. NEP hydrolyzed 0.1 mM SP, NT and their C-terminal fragments at the following rates (mumol/min/mg): SP1-11 = 7.8, SP4-11 = 11.7, SP5-11 = 15.4, SP6-11 = 15.6, SP8-11 = 6.7, NT1-13 = 2.9, and NT8-13 = 4.0. Purified ACE rapidly inactivated SP as measured in bioassay. HPLC analysis showed that ACE cleaved SP at Phe8-Gly9 and Gly9-Leu10 to release C-terminal tri- and dipeptide (ratio = 4:1). The hydrolysis was Cl- dependent and inhibited by captopril. ACE released mainly C-terminal tripeptide from SP methyl ester, but only dipeptide from SP free acid. Modification of arginine residues in ACE with cyclohexanedione or butanedione similarly inhibited hydrolysis of SP, bradykinin and Bz-Gly-Phe-Arg (80-93%) indicating an active site arginine is required for hydrolysis of SP. ACE hydrolyzed NT at Tyr11-Ile12 to release Ile12-Leu13. SP, NT and their derivatives (0.1 mM) were cleaved by ACE at the following rates (mumol/min/mg): SP1-11 = 1.2, SP methyl ester = 0.7, SP free acid = 8.5, SP4-11 = 2.4, SP5-11 = 0.9, SP6-11 = 1.4, SP8-11 = 0, NT1-13 = 0.2, and NT8-13 = 1.3. Peptide substrates were used as inhibitors of ACE (substrate = FA-Phe-Gly-Gly) and NEP (substrate = Leu5-enkephalin).(ABSTRACT TRUNCATED AT 250 WORDS)