Stereochemical analysis and biological activity of 3-hydroxy-leukotriene B4: a metabolite from ethanol-treated rat hepatocytes

Leukotriene B4 (LTB4), a biologically active metabolite derived from arachidonic acid by the 5-lipoxygenase cascade, is inactivated by cytochrome P-450-dependent omega-hydroxylation followed by second oxidation into a omega-carboxyl group. In many tissues, this second step is mediated by alcohol dehydrogenase. Isolated rat hepatocytes metabolized LTB4 in the presence of ethanol and ethoxyresorufin into substantial quantities of 3-hydroxy-LTB4 as determined by mass spectrometry. The absolute configuration of this metabolite was found to be greater than 98% 3(S)-hydroxy-LTB4 by comparison to synthetic standards. Investigation of the pharmacologic properties of the 3(S)- and 3(R)-hydroxy-LTB4 revealed that both caused a significant increase in intracellular free calcium in human neutrophils at 1 microM. Both enantiomers also induced thromboxane A2 release from the isolated guinea pig lung in a dose-dependent manner. This activity was fully blocked by a specific LTB4 receptor antagonist, LY223982, with an IC50 of 0.21 microM for LTB4. These results suggested that activation of the LTB4 receptor does not involve significant recognition of the carbon atoms close to the carboxyl moiety of LTB4. The failure of the hepatocyte to metabolically inactivate LTB4 in the presence of ethanol may be of importance to humans, particularly because the bioactive metabolite 3(S)-hydroxy-LTB4 was further metabolized by human neutrophils significantly more slowly than LTB4.

Eosinophil 15-lipoxygenase is a leukotriene A4 synthase

5-Lipoxygenase is the first committed enzyme in the leukotriene biosynthetic pathway and is known to catalyze not only the first oxygenation of arachidonate to form 5(S)-hydroperoxyeicosatetraenoic acid (5(S)-HPETE), but also dehydration of this intermediate into leukotriene A4 (LTA4) by an activity termed leukotriene A4 synthase. Inhibition of cytosolic 5-lipoxygenase prepared from human blood granulocytes with zileuton (100 microM) was virtually complete, but LTA4 synthase activity was only inhibited by 47%. Structural characterization of eicosanoids synthesized in these preparations revealed an abundance of 15-lipoxygenase metabolites including 15-HETE when arachidonate was used as substrate and 5(S),15(S)-dihydroxy-6,8,11,13(E,E,Z,Z)-eicosatetraenoic acid when 5(S)-HPETE was used as substrate. When neutrophils were prepared that contained less than 1% eosinophil contamination, zileuton was found to almost completely inhibit all 5-lipoxygenase, as well as LTA4 synthase products. Immunochemical analysis of the supernatants from purified neutrophils and eosinophils confirmed the previous observation that neutrophils do not express 15-lipoxygenase. Incubation of 5(S)-HPETE with recombinant mammalian 15-lipoxygenase resulted in the formation of 6-trans-LTB4 and 6-trans-12-epi-LTB4 as LTA4 products, as well as the 12-lipoxygenase product 5(S),12(S)-diHPETE. The mechanism of action of 15-lipoxygenase acting as an LTA4 synthase is proposed to involve removing the pro-R hydrogen atom at carbon-10 of 5(S)-HPETE, which is antarafacial to the hydroperoxy group to yield LTA4.

Constitutive expression of B-myb can bypass p53-induced Waf1/Cip1-mediated G1 arrest

Overexpression of wild-type p53 protein has been shown to induce arrest in the G1 stage of the cell cycle and to transactivate expression of the gene that encodes the 21-kDa Waf1/Cip1 protein, a potent inhibitor of cyclin-dependent kinase activity. p53-dependent G1 arrest is accompanied by decreased expression of the B-myb gene, a relative of the c-myb cellular oncogene. In this study we show that B-myb expression is required for cells to progress from G1 into S phase and that high levels of ectopic B-myb expression uncoupled from cell cycle regulation rescues cells from p53-induced G1 arrest even in the presence of Waf1/Cip1 transactivation and inhibition of cyclin E/Cdk2 kinase activity. Cotransfection experiments with p53 expression plasmids and expression plasmids encoding in-frame deletion mutations in B-myb coding sequences indicate that the DNA-binding domain of the B-Myb protein is required for this activity. These results provide evidence of a bypass of p53-induced Waf1/Cip1-mediated cell cycle regulatory pathways by a member of the myb oncogene family.

Site-specific water relations and stomatal response of Quercus ilex in a Mediterranean watershed

Intraspecific variations in the water relations and stomatal response of Quercus ilex L. were analyzed under field conditions by comparing trees at two locations within a Mediterranean watershed (l'Avic, Catalonia, NE Spain). Distinct environmental gradients exist between the two sites (referred to as ridge top at 975 m and valley bottom at 700 m) with greater soil depth for water storage, reduced radiation, reduced wind and higher water vapor pressure deficits at the valley bottom than at the ridge top. Osmotic adjustment and changes in tissue elasticiity did not significantly increase drought resistance in the trees studied. The leaf-to-air vapor pressure difference (Deltaw) threshold for inducing stomatal closure was higher at the ridge top (15.6 kPa MPa(-1) +/- 0.5 SE) than at the valley bottom (9.8 kPa MPa(-1) +/- 1.0 SE). However, increases in Deltaw beyond the threshold were followed by greater reductions in leaf conductance of trees at the ridge top than at the valley bottom. At both sites, maximum leaf conductance was related to predawn shoot water potential which, in turn, was related to watershed stream flow. The effects of water deficits during the dry summer of 1989 were more severe in trees at the valley bottom than at the ridge top. During periods of high evaporative demand, site-specific differences in the control of water loss led to more conservative water use by trees at the ridge top and, thus, to even greater drought avoidance (higher predawn water potentials) in late summer.

Prostacyclin production by different human grafts employed in coronary operations

Segments of human saphenous vein, internal mammary artery, right gastroepiploic artery, and inferior epigastric artery were incubated in vitro in Krebs-Henseleit solution and compared in terms of their capacity to generate and release into the medium 6-keto-prostaglandin F1 alpha (PGF1 alpha), the stable metabolite of prostacyclin. The four vascular conduits were also challenged with endothelin-1 (40 ng/mL), and accumulation of the lipidic material in the bathing fluid was also studied. The results obtained show clearly that under both normal and endothelin-1-stimulated conditions, the four vascular segments generate a substantial amount of 6-keto-PGF1 alpha. Multiple-comparisons analysis of the results indicates that the rank order in producing 6-keto-PGF1 alpha is as follows: inferior epigastric artery > internal mammary artery > right gastroepiploic artery > saphenous vein (p < 0.01). A similar order of potency was obtained in vascular conduits stimulated with endothelin-1. The rate of formation of immunoreactive 6-keto-PGF1 alpha under both normal and stimulated conditions by the inferior epigastric artery (normal, 301 +/- 8 pg/mg of tissue; stimulated, 519 +/- 15 pg/mg of tissue) was at 10 minutes more than 2 times (p < 0.01) that of the saphenous vein and about 1.5 times (p < 0.01) that of the right gastroepiploic artery.(ABSTRACT TRUNCATED AT 250 WORDS)

[The "arrhythmic pattern": a new method with prognostic significance in myocardial infarct]

OBJECTIVES

To establish a score or arrhythmic pattern for the prediction of long-term cardiac deaths on patients who have survived to the first acute myocardial infarction.

PATIENTS AND METHODS

We studied prospectively 200 patients that survived at a first myocardial infarction and in whom ambulatory ECG monitoring during 24 hours between days 7th and 18th (mean 12th) from the infarction was performed. The mean follow-up time was 51 +/- 18 months. The number and type of ventricular arrhythmias were analyzed and a score was measured, accordingly with Castellanos and Lown's classifications. An "arrhythmic pattern" or "total punctuation" was defined and compared among two groups: group 1 > 65 points and group 2 < 65 points.

RESULTS

The differential characteristics of both groups were: age (60 +/- 9 versus 56 +/- 10 years old; p = 0.004); hypertension (63% versus 29%; p < 0.001); clinic stage II-III (23% versus 11%; p = 0.02); echocardiographic ejection fraction (45 +/- 11% versus 50 +/- 10%; p = 0.04); positive exercise testing (73% versus 56%; p = 0.01); arrhythmias on the exercise test (15% versus 25%; p = 0.006). The long-term cardiac mortality was 25% versus 6% (p = 0.01), with an incidence of sudden death of 11% versus 3% (p < 0.05). Specificity, sensibility, positive predictive value and negative predictive value (reference cut point of 100) were 94, 65, 71 and 91%, respectively.

CONCLUSIONS

The use of a score of arrhythmic pattern may identify 2 groups of patients with different clinic profiles that probably justify a different long-term prognosis after a first acute myocardial infarction.

Reoperative cardiac valve surgery: a multivariable analysis of risk factors

From December 1983 to March 1992, of 1650 patients who underwent a cardiac valve procedure 41 (2.5%) underwent reoperation on prosthetic heart valves. The indications for reoperation were: structural degeneration (13 patients, 32%), non-structural dysfunction (nine patients, 22%), prosthetic valve endocarditis (seven patients, 17%), valve thrombosis (four patients, 10%), native valve pathology (three patients, 7%), aortic ascending pathology (five patients, 12%). The hospital mortality rate for mitral valve reoperation was 12% (two of 17) and for reoperation on the aortic prosthesis 26% (five of 19). No deaths occurred for associated mitral and aortic replacement (zero of five). The mortality rate for associated procedures was 24% (four of 17) versus 12% (three of 24) for isolated procedures. Preoperative and operative variables were analysed to determine risk factors for hospital mortality. New York Heart Association functional class, ascites, endocarditis and surgical timing had a univariate influence on operative mortality. The pulmonary capillary wedge pressure and preoperative creatinine level were also higher in non-survivors. Elective reoperation had a mortality rate of 7%, while that for emergency procedures was 38%. Multivariable analysis indicated a longer extracorporeal circulation time and the urgent-emergency status as predictors of mortality. Reoperation before severe haemodynamic impairment occurs is recommended.

An improved assay for urinary LTE4

An improved method for the measurement of urinary LTE4 is described, based on the combined use of solid phase extraction (SPE)-HPLC-enzyme-immunoassay (EIA). This allows the use of homologous radioactive tracer in easily measurable amount for HPLC retention time evaluation and recovery estimation. Recovery linearly correlated with the total amount of LTE4 present in the extracted sample, indicating the existence of a carrier effect. Identification of immunoreactivity in HPLC fractions as LTE4 was based on parallel dilution assay and confirmed by the observable isotopic separation between tritium labeled LTE4 and immunoreactive LTE4. Critical selection of urine sample size, on the basis of creatinine content, together with efficient purification by SPE, resulted in total absence of aspecific immunoreactivity in fractions surrounding those associated with LTE4. Urinary LTE4 was measured in normal subjects and in cirrhotic patients, where an increased LTE4 excretion has been reported. The method described fulfils the criteria of specificity, sensitivity and accuracy necessary for a potential successful use in the study of sulfidopeptide leukotrienes formation in normal and pathological conditions.

Correlation between E2F-1 requirement in the S phase and E2F-1 transactivation of cell cycle-related genes in human cells

The mammalian nuclear protein E2F-1 has recently been cloned based on its ability to bind the retinoblastoma protein. To determine whether E2F-1 plays a role in the control of the cell proliferation, we introduced an inducible construct expressing an E2F-1 antisense RNA into the human glioblastoma T98G cell line and assessed DNA synthesis during the cell cycle. Expression of the antisense transcripts during the G1-S transition resulted in a marked delay in the completion of DNA synthesis. Band-shift analysis of bacterially produced E2F-1 showed that this protein bound to the promoters of human DNA polymerase-alpha, cyclin D1, and c-myb but not to the cdc2 gene promoter. E2F-1 also transactivated the bound promoters in transient transfection assays. These results suggest a major role for E2F-1 in the control of cell cycle progression via transcriptional regulation of proliferation-associated genes.

Effects of nedocromil sodium on bronchospasm and HS-NCA release induced by allergen inhalation in asthmatic patients

The aim of this study was to assess the ability of nedocromil sodium (NS) to prevent the immediate asthmatic reaction and the increase in the serum level of heat stable neutrophil chemotactic activity (HS-NCA) induced by antigen inhalation. In a double-blind, cross-over study, 13 atopic subjects affected with seasonal asthma underwent a bronchial provocation test with a preselected dose of grass pollen allergen (enough to cause a decrease of > or = 20% in FEV1:FEV1 PD20) after pre-treatment with 4 mg NS or placebo. Serum samples were withdrawn from 11 subjects for HS-NCA determination. After NS administration the decrease in FEV1 was significantly less than after placebo administration at all time points after challenge (2 min P = 0.0004; 7 min, P = 0.0005; 17 min P = 0.0002 and 27 min P = 0.0005). The percentage increase in HS-NCA was significantly higher after placebo than after NS inhalation, both 10 (P = 0.0048) and 20 (P = 0.0068) min after challenge. Our study confirms previous investigations, showing that NS inhibits the immediate asthmatic response to allergen inhalation in atopic, asthmatic subjects and moreover it shows that this drug prevents in vivo the increase of the serum HS-NCA. This last finding has not been previously reported.

Effects of loratadine on cytosolic Ca2+ levels and leukotriene release: novel mechanisms of action independent of the anti-histamine activity

Loratadine, a non-sedating anti-histamine drug, displays in vitro potential anti-allergic properties not related to its interaction with the histamine H1 receptor. In a search for the mechanisms of these actions, we have found that loratadine induces an elevation of cytosolic calcium ion, [Ca2+]i, in rat peritoneal macrophages or human platelets. The mechanism of this elevation resides in the ability of loratadine to discharge intracellular Ca2+ stores, similarly to thapsigargin. This in turn brings about the inhibition of [Ca2+]i rise induced by physiological activators (platelet activating factor and ADP), as well as by thapsigargin. One of the active metabolites of loratadine, descarbo-ethoxy-loratadine, and another anti-histamine, namely terfenadine, exhibit the same effects. In addition, loratadine partially inhibits antigen-induced leukotriene release from human bronchi, but is unable to inhibit the concomitant contraction. We conclude that loratadine can interfere with the mechanisms controlling Ca2+ release, thus inhibiting the cell activation elicited by various agonists through [Ca2+]i elevation. This might be the mechanism underlying its anti-allergic actions in vitro. Furthermore, loratadine might represent an interesting tool in the study of Ca2+ homeostasis.

[Process assessment in the care for patients with chronic degenerative disease in a basic health unit]

The efficacy of health actions, related to arterial hypertension and used as a strategy to decrease morbimortality due to cardiovascular diseases, in accordance with the "risk approach" and carried out in a Primary Health Care Clinic is assessed. These actions are based on the detection of arterial hypertension in the adult population attended at the Clinic and on the control of blood pressure levels in hypertensive individuals in which other known risk factors continue to be controlled, as well as on further treatment of eventual complications. Data relating to the 3,793 patients who were attended at least once by doctors of the adult sector of a training health-center located in S. Paulo county (Brazil) during the period from June 1990 to May 1991, inclusive, were evaluated. This evaluation was made according to each diagnosis undertaken as well as to the concentration of each type of consultation whether occasional, or follow-up. Of these 3,793 patients analysed, 839 presented arterial hypertension and/or diabetes, and were grouped into four categories: the exclusively hypertensive, the hypertensive with other associated chronic diseases (except diabetes), the diabetic and the diabetic with arterial hypertension. The results of this study brought the following aspects to light: 1) The low coverage of hypertensive individuals and diabetics being attended by the health service when only the population attended by the health service is taken into consideration. 2) The incidence of patients diagnosed as hypertensive in occasional consultations who did not return to the health service for medical follow-up indicates the difficulties involved in attracting such individuals permanently.(ABSTRACT TRUNCATED AT 250 WORDS)

Formation of sulphidopeptide-leukotrienes by cell-cell interaction causes coronary vasoconstriction in isolated, cell-perfused heart of rabbit

1. We have studied the transcellular biosynthesis of bioactive leukotrienes (LTs), generated upon blood cell-vascular wall interactions and their functional consequences, in the spontaneously beating, cell-perfused, heart of the rabbit. Rabbit isolated hearts were perfused under recirculating conditions (50 ml) with 5 x 10(6) cells of unpurified (buffy coat) or purified human neutrophils (PMNL), and challenged with 0.5 microM A23187 for 30 min. Coronary perfusion pressure (CPP), heart rate (HR), left ventricular end-diastolic pressure (LVEDP) and left ventricular pressure (LVP) were monitored continuously. Leukotriene formation was measured by specific enzyme-immunoassay and confirmed by reversed phase h.p.l.c. and u.v. spectral analysis. 2. Basal CPP values averaged 44 +/- 1.4 mmHg; A23187 triggered a marked increase in CPP both in the presence of buffy coat cells (+100% above basal) and PMNL (+270% above basal); the latter change in CPP was accompanied by a rise in LVEDP (+138% above basal). 3. The increase in CPP was preceded by a statistically significant rise in iLTC4-D4 concentration in the circulating buffer. Pretreatment with two structurally unrelated LTD4 receptor antagonists, LY171883 and SKF104353 (10 microM), fully prevented the increase in CPP and LVEDP. A similar protection was also observed when the rabbit heart was perfused with PMNL that had been pretreated with MK886 (1 microM), a potent inhibitor of leukotriene biosynthesis. 4. The increased coronary tone was accompanied by a marked release of lactate dehydrogenase (LDH), a marker of ischaemic damage; pretreatment of the heart with the LTD4 receptor antagonists as well as of the PMNL with MK886 resulted in a complete suppression of LDH activity release. 5. Positive identification of LTC4-D4 in the perfusates was obtained and a significant correlation observed between the CPP values and iLTC4-D4 concentrations.6. This study suggests that challenge of PMNL present within the coronary vasculature, causes a LTD4-dependent coronary vasoconstriction, favoured by an efficient uptake of PMNL-derived LTA4 by endothelial cells. The activation of the 5-lipoxygenase pathway in the context of tight interactions between blood cells and coronary vasculature, is suggested to have an important outcome in the alterations of coronary flow and cardiac contractility.

Intracardiac ectopic thyroid: conservative surgical treatment

The case of a patient with an intracardiac ectopic thyroid is reported. A cardiac tumor was found in a 66-year-old woman and was diagnosed by two-dimensional echocardiography. An intraoperative biopsy was performed, and the mass was recognized as an ectopic thyroid and treated with a conservative surgical approach because of the size, location, and relationship to adjacent structures. The 60-month follow-up shows normal echocardiographic images and the good clinical status of the patient.

Antimicrobial resistance among clinical isolates of Haemophilus influenzae in northern Italy. Collaborative Study on Pediatric Infectious Diseases

Only scanty data are available on the susceptibility of Haemophilus influenzae in Italy. The in vitro activity of ampicillin, ampicillin-sulbactam, cefaclor, cefuroxime, cefotaxime, chloramphenicol, erythromycin and trimethoprim-sulfamethoxazole against 327 strains of Haemophilus influenzae (55 encapsulated, 272 non-typeable) isolated from adults and children in northern Italy, between January 1984 and December 1989, was compared. Patients were affected by meningitis or other invasive infections, conjunctivitis, otitis, sinusitis, pneumonia or bronchitis. Minimal inhibiting concentrations were determined by a microdilution technique in Mueller Hinton broth supplemented with 10 microliters/ml NAD and 2-5% lysed horse blood. A concentration of 1 x 10(5) to 5 x 10(5) CFU/ml was used as the inoculum. The antibiotics were tested at concentrations ranging from 0.03 to 64 microliters/ml with the exception of trimethoprim-sulfamethoxazole, for which the range of concentrations examined were 0.01/0.25 to 32/512 microliters/ml. All the strains tested were susceptible to ampicillin-sulbactam, cefuroxime and cefotaxime, and more than 95% were susceptible to ampicillin, cefaclor and chloramphenicol. Only 4% were susceptible to erythromycin but most minimal inhibiting concentrations fell into the intermediate category. Strains isolated from adults were more susceptible to trimethoprim-sulfamethoxazole than strains isolated from children (85% vs 66%; p = 0.011).

Regulation of BALB/c 3T3 fibroblast proliferation by B-myb is accompanied by selective activation of cdc2 and cyclin D1 expression

The B-myb gene is expressed in many cell types at the G1/S transition of the cell cycle. Inhibition of B-myb expression in BALB/c 3T3 fibroblasts by introduction of a B-myb antisense construct greatly diminished cell proliferation, whereas constitutive expression of a human B-myb cDNA in these cells reduced their growth factor requirements and induced a transformed phenotype. Constitutive expression of B-myb cDNA was accompanied by activation of cyclin D1 and cdc2 expression but not of cyclin A and cyclin B. Transfection of BALB/B-myb cells (a cell line expressing high levels of exogenous human B-myb) with a cyclin D1 antisense construct drastically reduced cloning efficiency of these cells. These results suggest that the B-myb-encoded product regulates fibroblast proliferation by activating cdc2 and cyclin D1 gene expression and that abnormal expression of cyclin D1 might be a step in the process of transformation.

Inhibition of Friend leukemia cell visceral metastases by a new monoclonal antibody and role of the immune system of the host in its action

We developed a syngeneic mouse IgG2a monoclonal antibody (MAb) A9D41 directed against the Friend leukemia virus envelope gp70 antigen present on the cell surface membranes of virus producer 3C18 Friend leukemia cells (FLC). A9D41 showed a marked antitumor activity in DBA/2 mice given injections of gp70 positive 3C18 FLC, but it was ineffective in mice given injections of gp70 negative 745 FLC or unrelated tumor cells. A9D41 was particularly effective in inhibiting the development of 3C18 FLC liver and spleen metastases. MAb was also effective as adjuvant therapy in inhibiting visceral metastases after excision of an established s.c. FLC tumor, and combined therapy of A9D41 with mouse interferon alpha/beta was more effective than MAb or interferon alpha/beta alone. The immune system of the host played a decisive role in the antimetastatic action of A9D41. Thus, although MAb was cytotoxic for 3C18 FLC in vitro in the presence of rabbit complement, the F(ab')2 fragment was ineffective in vivo, and the antitumor effect of MAb was abolished in mice treated with an antibody to CD4 and diminished in natural killer cell-deficient beige and athymic nude mice. MAb-treated mice surviving injection of FLC developed an immune response to 3C18 FLC.

[The use of the inferior epigastric artery as alternative conduit for myocardial revascularization: our experience]

When complete revascularization can not be obtained with the internal mammary artery and saphenous veins, the inferior epigastric artery may be an excellent alternative conduit. We describe our experience with this conduit, review the anatomy of this artery, and present the evolution of our harvesting technique through a pararettal approach. Proximal anastomoses were made first with the aid of an oval cuff of the common femoral artery (5 cases, Group A). Two patients (40%) of this group studied postoperatively revealed a graft occlusion. In the last 13 cases (Group B) we tailored the proximal anastomoses directly to the aorta. All patients studied postoperatively showed patent inferior epigastric artery grafts. There were no hernias and no deaths. Inferior epigastric artery can be considered a good alternative conduit in myocardial revascularization.

Intraduodenal absorption in the rabbit of a novel heparin salt

The intraduodenal absorption of a new low-molecular-weight heparin (LMWH) diamine salt (ITF 1331) was compared with the parent compound ITF 1060 and with sodium LMWH, in anaesthetized rabbits. The administration of either salt, but not of sodium LMWH, resulted in a dose-related increase in plasma anti-Xa activity. In this respect ITF 1331 was slightly superior to ITF 1060, and in acute-toxicity studies the counterion itself (ITF 258) was less toxic than that in ITF 1060 (counterion No. 4). These data confirm that a tertiary diamine within the counterion is an important structural requirement for the bioavailability of heparin by the intraduodenal route, and suggest that ITF 1331 may represent an important advance in the search for an oral heparin.

Negative ion tandem mass spectrometry of leukotriene E4, and LTE 4, metabolites: Identification of LTE 4, in human urine

The sulfidopeptide leukotrienes, leukotriene E4, (LTE4,) and its N-acetyl derivative and several ω- and β-oxidized metabolites of LTE4, have been analyzed by tandem mass spectrometry. [M-H](-) ions were produced by continuous flow fast atom bombardment, and collision-induced dissociation of these ions was studied by using a triple quadrupole instrument. The product ion spectra obtained were characteristic of the structure of LTE4, and mechanisms of ion formation were investigated by using deuterated compounds. β-Elimination of the peptide portion of LTE4, by loss of CO2, and ethylene amine leaves the C-l carboxyl group ionized in the most abundant fragment ion for LTE4, and all metabolites. Tandem mass spectrometry of fast atom bombardment-generated anions from ω- and β-oxidized metabolites of LTE4, produced similar ions with only a minor influence of the third carboxyl group at the omega terminus evident. Tandem mass spectrometry was used to identify unequivocally the presence of unmodified LTE4, in a high performance liquid chromatography-purified fraction of urine from a normal healthy volunteer after infusion with LTE4.

Structural identification of cytochrome P450-dependent arachidonate metabolites formed by rabbit medullary thick ascending limb cells

The medullary thick ascending limb of Henle's loop (mTALH) contributes importantly to the regulation of extracellular fluid volume and composition and metabolizes arachidonic acid (AA) chiefly by a cytochrome P450 monooxygenase pathway. Rabbit mTALH cells, when incubated with radiolabeled [14C]AA, form products that segregate into two peaks designated P1 and P2 based on their reverse-phase high pressure liquid chromatography retention times. We have now definitively identified their chemical structures. mTALH cells, isolated from the rabbit outer medulla, were homogenized and incubated with [14C]AA in the presence of NADPH. The AA metabolites in P1 and P2 were identified by gas chromatographic-mass spectrometric methods, including fast atom bombardment, negative ion electron capture, and electron ionization. All mass spectrometric data, the lack of UV chromophores, and comparisons with authentic standards were consistent with P1 containing two principal components: 19-hydroxy-5,8,11,14 eicosatetraenoic acid (19-HETE) and 20 - hydroxy - 5,8,11,14 - eicosatetraenoic acid (20-HETE), P2 contained primarily 1,20-eicosa-5,8,11,14-tetraenedioic acid (20-COOH-AA). The biological properties of P1 and P2 were compared with those of the authentic standards of 19- and 20-HETE and 20-COOH-AA. P1 dose dependently relaxed precontracted mesenteric arterial rings, as did authentic (19S)- and (19R)-HETE, whereas 20-HETE relaxed at lower and contracted at higher concentrations. As P1 contained a mixture of 19- and 20-HETE, each of these AA metabolites presumably contributed to the vascular relaxation produced by P1. Neither P2 nor 20-COOH-AA exhibited vasoactivity, but each demonstrated a similar potency in inhibiting rabbit medullary Na(+)-K(+)-ATPase activity. As previously reported, P2 was a more potent inhibitor of Na(+)-K(+)-ATPase than P1. The lesser inhibitory activity of P1 presumably reflects the presence of similar amounts of 19-HETE, the least active metabolite, and 20-HETE, which resembles 20-COOH-AA in its capacity to inhibit Na(+)-K(+)-ATPase. Thus, the biological activity of the less polar peak, P1, can be accounted for by 19- and 20-HETE, and that of P2, by 20-COOH-AA.

Direct airway injury results in elevated levels of sulfidopeptide leukotrienes, detectable in airway secretions

Sulfidopeptide leukotrienes (LTC4/D4/E4) are suspected to be important lipid mediators in inflammatory responses in the lung. Previous investigations have provided evidence to support enhanced synthesis and secretion of these eicosanoids into bronchoalveolar lavage fluid in patients with Adult Respiratory Distress Syndrome (ARDS). We have prospectively examined the relationship between sulfidopeptide leukotriene levels in tracheal aspirates of 14 intubated and mechanically ventilated patients. When compared with the aspirate from one patient who required ventilation because of respiratory muscle weakness, the tracheal aspirates from eight ARDS patients had elevated leukotriene levels (range 2020-2052 pg/aspirate). However, the aspirates from four of the five patients with direct airway injury [inhalational burn (n = 3) and massive aspiration of gastric contents (n = 2)] contained significantly higher amounts of sulfidopeptide leukotrienes (range 10309-52244 pg/aspirate). Three of the five patients with direct airway injury did not develop ARDS. We conclude that simple aspiration of tracheal secretions can be used to monitor airway leukotriene biosynthesis in patients with lung injury and that elevated airway leukotriene levels may reflect airway epithelial damage, but may not predict the development of ARDS.

Synthesis and in vitro antibacterial properties of 2-(3-bromo-5-isoxazolylideneamino-oxy)acetamido-beta-lactam derivatives

The synthesis of new 2-(3-bromo-5-isoxazolylideneamino-oxy)acetic acids and their condensation derivatives with suitable beta-lactam nuclei is reported. Their antibacterial properties have been tested in vitro. An interesting activity against Gram-positive bacteria including beta-lactamase-producing microorganisms was found among the cephalosporanic acid derivatives.

Host humoral and cellular immune mechanisms in the continued suppression of Friend erythroleukemia metastases after interferon alpha/beta treatment in mice

DBA/2 mice were injected intravenously with 2 x 10(6) 3C18 Friend erythroleukemia cells (FLC), a cell line resistant to interferon alpha/beta (IFN-alpha/beta). Although daily administration of mouse IFN-alpha/beta markedly increased the mean survival time, most IFN-treated mice continued to harbor FLC in different organs. To investigate the mechanisms responsible for this persistent suppression of FLC growth in IFN-treated mice, we undertook a series of adoptive transfer experiments with sera and spleen cells. Sera from FLC-injected, IFN-treated mice were very effective in conferring protection on DBA/2 mice even when injected systemically (intravenously) 18-24 h before intravenous challenge with FLC. These sera also exhibited antitumor activity when injected subcutaneously or intraperitoneally together with FLC. The protective factor in serum was shown to be an immunoglobulin. FLC-injected, IFN-treated mice developed antibodies to FLC demonstrable by radioimmunoassay and complement-dependent cytotoxicity. Sera from these mice recognized a specific 65-kD FLC membrane antigen(s) not detectable on membrane extracts from RBL-5 or ESb tumor cells, or on normal spleen cells. FLC-injected, IFN-treated mice also developed a specific cellular response demonstrable by transfer of protection with spleen cells injected intravenously or subcutaneously. Analysis of the responsible spleen cell populations indicated that the effector cells were neither T nor B cells. These results demonstrating the importance of host humoral and cellular immune mechanisms in the persistent suppression of FLC in IFN-treated mice may be relevant to the use of IFN-alpha/beta in patients in whom tumors may regress and tumor cells may then remain latent for extended periods of time.

Systemic to pulmonary bronchial blood flow in mitral stenosis

We measured systemic to pulmonary bronchial blood flow [Qbr(s-p)] during total cardiopulmonary bypass in 15 patients with mitral stenosis and elevated pulmonary venous pressure (group A, mean pulmonary wedge pressure = 22.2 +/- 5.4 mm Hg, mean +/- SD) and in 15 patients with coronary artery diseases and normal pulmonary venous pressure (group B). Qbr(s-p) is the volume of blood accumulating in the left side of the heart in the absence of pulmonary and coronary flows. This blood was vented through a cannula introduced into the left atrium and measured. Qbr(s-p) was 76.3 +/- 13.9 ml/min (2.18 +/- 0.37 percent of extracorporeal circulation pump flow) and 22.3 +/- 2.1 (0.63 +/- 0.15) in group A and B, respectively (p less than 0.01). During total cardiopulmonary bypass, pulmonary venous pressure is approximately atmospheric pressure, and no differences in systemic blood pressure, extracorporeal circulation pump flow, and airways pressure were observed between group A and B. Therefore, vascular resistance through the bronchial vessels draining into the pulmonary circulation is reduced in patients with mitral stenosis and elevated pulmonary venous pressure.

Synthesis and antifungal properties of 3-bromo-4,5,6,7-tetrahydro-1,2-benzoisoxazole derivatives

The synthesis of 3-bromo-4,5,6,7-tetrahydro-1,2-benzoisoxazole derivatives and their activity against human pathogen fungi are reported. In particular, compound 3,5-dibromo-6,7-dihydro-1,2-benzoisoxazol-4-(5H)-one showed a broad antifungal spectrum and good fungicidal activity against Trichophyton mentagrophytes.

In-vitro susceptibility of Haemophilus influenzae to loracarbef (LY 163892) and other oral antibiotics. Collaborative Study Group on Pediatric Infectious Disease in Lombardy

Data on susceptibility of Haemophilus influenzae are scanty in Italy. We compared the activity of loracarbef (Ly 163892), a new carbacephem, with that of 4 other agents against 265 strains of H. influenzae (46 type b, 219 nontypable) isolated from adults and children at Istituti Clinici di Perfezionamento of Milano, between 1/1/84 and 1/1/89, and also from 7 children at pediatric departments in Lombardy during 1988. In adults 72 strains were all isolated from sputum of patients with pneumonia or chronic bronchitis; in children 199 strains were isolated from conjunctiva (53% of the patients had also a concomitant respiratory infection), 24 from middle ear, 18 from sputum and 32 from blood or cerebrospinal fluid. Minimal inhibiting concentrations (MIC) were determined by the broth microdilution technique. The incidence of resistance of H. influenzae to ampicillin was 3.8%; the lowest percentage of resistance was found for loracarbef (0%) and the highest for erythromycin (94% for strains isolated from children and 97% for strains isolated from adults).

Leukotriene E4 elimination and metabolism in normal human subjects

Radiolabeled leukotriene (LT) E4 was infused into three healthy subjects in order to assess the production and elimination of sulfidopeptide leukotriene metabolites in urine. Three different radiolabeled tracers were employed, [14,15-3H]LTE4, [35S]LTE4, and [14C] LTE4 in five separate infusion studies. There was a rapid disappearance of radioactivity from the vascular compartment in an apparent two-phase process. The first elimination phase had an apparent half-life of approximately 7 min. Radioactivity quickly appeared in the urine with 10-16% eliminated during the first 2 h following intravenous infusion; 7%, 2-5 h; 4%, 5-8 h; 4%, 8-15 h; and 1.5%, 15-24 h from the [14C] LTE4 experiments. Unmetabolized LTE4 was the major radioactive component in the first urine collection, but at later times two more polar compounds predominated. After extensive purification by normal phase-solid phase extraction and reverse-phase high performance liquid chromatography, these compounds were characterized by UV spectroscopy, co-elution with synthetic standards, negative ion electron capture gas chromatography/mass spectrometry, and tandem mass spectrometry. The two major urinary metabolites were structurally determined to be 14-carboxy-hexanor-LTE3 and the conjugated tetraene, 16-carboxy-delta 13-tetranor-LTE4. Three other minor metabolites were detectable in the first urine collection only and were characterized by co-elution with synthetic standards as 16-carboxy-tetranor-LTE3, 18-carboxy-dinor-LTE4, and 20-carboxy-LTE4. omega-Oxidation and subsequent beta-oxidation from the methyl terminus appeared to be the major metabolic fate for sulfidopeptide leukotrienes in man. The accumulation of the 14-COOH-LTE3 and 16-COOH-delta 13-LTE4 may reflect a rate-limiting step in further oxidation of these compounds which places a conjugated triene or conjugated tetraene, respectively, two carbons removed from the CoA ester moiety. Also in the first urine collection there was another minor metabolite identified as N-acetyl-LTE4, however, no subsequent beta-oxidation of this metabolite was observed. The major metabolites of LTE4 might be useful in assessing in vivo production of sulfidopeptide leukotrienes in humans.

Prostaglandins and gastric mucosal protection by esaprazole in rats

Esaprazole, N-cyclohexyl-1-piperazineacetamide monohydrochloride, was studied for its activity to prevent gastric mucosal damage induced by several necrotizing agents in the rat. Its effects on acid gastric secretion and the role of gastric mucosal prostaglandin generation were also investigated. Esaprazole, given orally, dose dependently prevented the formation of mucosal damage induced by absolute ethanol, 0.2 N NaOH or 0.6 N HCl. This activity occurred at doses lower than the antisecretory doses. Esaprazole was also found to increase the gastric mucosal prostaglandin content but at doses that exceeded the cytoprotective doses. The failure of indomethacin to impair the gastric mucosal protection provided by esaprazole suggests that mechanisms other than mobilization of endogenous prostaglandins may be involved.

Mediator release after endobronchial antigen challenge in patients with respiratory allergy

The aim of the present study was to evaluate the release of some potential mediators of allergic reactions, such as histamine, peptide leukotrienes (LTs), LTB4 and prostaglandin D2 (PGD2), in bronchoalveolar lavage (BAL) fluids from 11 patients with respiratory allergy (eight with bronchial asthma and three with allergic rhinitis), who underwent specific endobronchial challenge. Histamine, peptide LT, and PGD2 levels in BAL fluids increased significantly after antigen stimulation both in patients with asthma and in patients with rhinitis. By contrast, LTB4 concentration was always below the limits of detection of the radioimmunoassay. In patients with asthma, histamine concentration increased from 5.3 +/- 0.6 ng/ml in lavages obtained before provocation to 20.2 +/- 5.8 ng/ml (mean +/- SEM; p less than 0.04) 5 minutes after bronchoprovocation. Peptide LTs increased from 0.32 +/- 0.08 to 0.82 +/- 0.21 ng/ml (p less than 0.02) and PGD2 from 0.06 +/- 0.01 ng/ml to 0.36 +/- 0.09 ng/ml (p less than 0.02). Elevated histamine, peptide LT, and PGD2 concentrations were also found in the 15-minute postchallenge BAL fluids. Similar results were obtained in patients with rhinitis. Histamine concentration was 3.4 +/- 0.6 ng/ml in prechallenge bronchial lavages and 11.3 +/- 1.7 ng/ml in postchallenge lavages; peptide LTs increased from 0.13 +/- 0.008 ng/ml to 0.73 +/- 0.21 ng/ml, and PGD2 from 0.05 +/- 0.01 ng/ml to 0.26 +/- 0.06 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)