Hemodynamic effects of oleic acid in newborn lambs: role of arachidonic acid metabolites.

Oleic acid injection produces acute lung injury and pulmonary hypertension in adult animals. In other types of acute lung injury, such as that caused by E. coli endotoxin, metabolites of arachidonic acid are important mediators of pulmonary hypertension. In order to understand the hemodynamic response of newborn animals to oleic acid injection and the contribution of arachidonic acid metabolites to that response, we injected oleic acid into awake, chronically instrumented newborn lambs. The hemodynamic response of lambs to injections of oleic acid alone was compared to their response after pretreatment with either FPL57231, a putative leukotriene receptor antagonist, or indomethacin, a cyclooxygenase synthesis inhibitor. Oleic acid caused acute pulmonary hypertension associated with an increase in protein-rich lung lymph fluid. Systemic hemodynamic effects were variable. FPL57231 completely blocked the oleic acid-induced pulmonary hypertension while indomethacin significantly attenuated the response. Therefore, metabolites of arachidonic acid metabolism appear to be important mediators of oleic acid-induced pulmonary hypertension in newborn lambs.     

Cytokine modulation of immune activation associated suppression of macrophage cyclooxygenase activity in vivo.

Intraperitoneal infection with Listeria monocytogenes (LM) results in activation of the peritoneal macrophage population which displays increased surface expression of major histocompatibility (MHC) Class II (Ia) antigen and markedly suppressed prostaglandin (PG) synthesis. We demonstrate here that this decrease in PG production is also seen after treatment by mitogen (Con A) and endotoxin (LPS), and can be explained by reduced cyclooxygenase activity in these cell populations. We show that, whereas Ia expression was augmented at all doses of LM and Con A tested, it displayed a biphasic response to LPS in vivo: increase at the lowest dose and inhibition at higher doses. In order to identify possible endogenous mediators of these responses, we used highly purified preparations of recombinant murine (rMu) cytokines and neutralizing cytokine specific monoclonal antibodies (MAbs) to examine whether interferon-gamma (IFN-gamma) and/or tumor necrosis factor (TNF) down-regulate macrophage cyclooxygenase activity in vivo. We found that IFN-gamma induced Ia expression but had no effect on PG secretion. In contrast, TNF-alpha suppressed PG synthesis and inhibited Ia surface expression. Similarly, in our model of Con A-induced peritoneal macrophage activation, pretreatment of animals with a neutralizing MAb to rMuIFN-gamma completely blocked the induction of Ia positive macrophages by Con A but did not affect Con A-dependent suppression of PG synthesis. Pretreatment with MAb to TNF had no effect on Con A-induced Ia levels, but significantly inhibited suppressed PG synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of fine needle aspiration as a screening test for occult prostatic carcinoma

As part of an ongoing study of objective parameters of prognostic value in prostatic carcinoma, a routine procedure was developed to aspirate all prostates prior to surgery. These targets were different from those of other workers in the field of prostatic fine needle aspiration (FNA), who generally advocate that FNA be confined to suspicious nodules. The aspirations were performed by a large group of practicing urologists who had no special training in prostatic FNA except for guidelines provided by their peers and information available in the literature. This approach permitted an assessment of the performance of FNA as a screening test rather than as a diagnostic procedure. During the period from January 1983 to February 1987, 1,683 patients had prostatic FNAs performed (plus subsequent histologic study). The following diagnoses were rendered: "inadequate/scanty specimen" in 625 cases (37%), "negative/atypical" in 844 cases (50%) and "suspicious/positive" in 214 cases (13%). Histologic examination showed stage A1 prostatic adenocarcinoma in 18 patients. The cytologic diagnoses on these 18 patients were inadequate/scanty in 3 (17%), negative/atypical in 13 (72%) and suspicious/positive in 2 (11%). Of the 214 patients with a positive/suspicious diagnosis by FNA, the diagnosis of prostatic carcinoma was confirmed by tissue evidence in 200; the other 14 patients had either no evidence of prostatic carcinoma on surgical biopsy (needle biopsy/transurethral resection/suprapubic prostatectomy) or had no surgical biopsy. Eight of the 14 patients developed clinical evidence of carcinoma, 1 died of urinary bladder carcinoma and 1 was lost to follow-up. In the remaining four patients, there is still no evidence of prostatic carcinoma after about one-and-one-half years of follow-up. These results indicate that (1) specialized training is required in order to obtain adequate smears by prostatic FNA; (2) prostatic FNA is not a good screening technique for detecting stage A1 prostatic carcinoma; and (3) a positive diagnosis by prostatic FNA, even when not confirmed by tissue biopsy, is still an indication of disease.     

The expression of transthyretin mRNA in the developing rat brain

Specific cDNA and oligonucleotide probes were used to study the appearance of transthyretin mRNA in developing rat brain using Northern gel analysis, cytoplasmic dot hybridization, and in situ hybridization. Transthyretin mRNA in embryonic rat brain was found to be confined to the epithelial layer of the choroid plexus primordia appearing first in the fourth ventricle, followed by appearance in the lateral ventricles, and subsequently in the third ventricle. Transthyretin mRNA was localized in these cells from early stages of neuroepithelium differentiation, showing that it is a sensitive marker for the differentiation of the choroid plexus within the fetal brain.     

The oxidation of arachidonic acid by the cyclooxygenase activity of purified prostaglandin H synthase: spin trapping of a carbon-centered free radical intermediate

The ESR spin trapping technique was used to study the first detectable radical intermediate in the oxidation of arachidonic acid by purified prostaglandin H synthase. The holoenzyme and the apoenzyme, reconstituted with either hematin or Mn2+ protoporphyrin IX, were investigated. Depending on the different types of enzyme activity present, arachidonic acid was oxidized to at least two free radicals. One of these radicals is thought to be the first ESR detectable radical intermediate in the conversion of arachidonic acid to prostaglandin G2 and was detected previously in incubations of ram seminal vesicle microsomes, which are rich in prostaglandin H synthase. The ESR findings correlated with oxygen incorporation into arachidonic acid and prostaglandin formation, where the spin trap inhibits oxygen incorporation and prostaglandin formation by apparently competing with oxygen for the carbon-centered radical. Substitution of arachidonic acid by octadeuterated (5, 6, 8, 9, 11, 12, 14, 15)-arachidonic acid confirmed that the radical adduct contained arachidonic acid that is bound to the spin trap at one of these eight positions. An attempt was made to explain the apparent time lag between the metabolic activity observed in the oxygraph measurements and the appearance of the trapped radical signals.     

Effect of high-density lipoproteins with varying ratios of apolipoprotein A-I to apolipoprotein A-II on steroidogenesis by cultured rat ovary granulosa cells

Plasma high-density lipoproteins (HDL) can provide rat ovary steroidogenic tissue with cholesterol for steroid hormone production, but the mechanism of cholesterol transfer is unknown. To test the importance of apolipoprotein A-I (the major HDL apolipoprotein) in HDL-cell interactions, we examined the ability of canine-human HDL hybrids containing various proportions of canine apolipoprotein A-I and human apolipoprotein A-II to stimulate steroidogenesis by cultured rat ovary granulosa cells. We observed that as the apolipoprotein A-II to apolipoprotein A-II ratio decreased, the ability of the hybrid particles to stimulate granulosa cell progestin (progesterone and 20 alpha-dihydroprogesterone) production diminished. However, granulosa cell progestin (progesterone and 20 alpha-dihydroprogesterone) production diminished. However, apolipoprotein A-I was not necessary for cholesterol transfer, since hybrids with less than 5% of their total apolipoprotein mass as apolipoprotein A-I stimulated progestin production 30% as effectively as canine HDL, which contained essentially only apolipoprotein A-I. These data indicate that the delivery of cholesterol from HDL into the rat ovary cell for steroidogenesis is not strictly dependent on the presence of a specific HDL apolipoprotein.