Morphometrics of the human thumb metacarpal bone: interest for developing an osseointegrated prosthesis.

INTRODUCTION: Amputation of the thumb presents a serious insult to the hand and diminished quality of life for a patient physically, vocationally, and possibly psychologically. The aim of this study was to define the geometry of the thumb metacarpal in order to help create a standardized set of transcutaneous osseointegrated prostheses to treat patients who have suffered amputation of the thumb at the level of the metacarpophalangeal joint. MATERIALS AND METHODS: A total of 80 metacarpals from 46 cadavers were studied. All soft tissues were removed and the thumb metacarpals were imaged using computed tomography. Three-dimensional models were constructed using images from the coronal, sagittal, and axial planes. Using HyperMesh™ CAD software, the bones were analyzed for overall length, radius of curvature, medullary canal diameter, cortical thickness, and distance to the isthmus, defined as the narrowest portion of the intramedullary canal. RESULTS: The average length of the first metacarpal was 47.6 mm (±3.3 mm, 39.2-56.9 mm). The average radius of curvature was 55.5 mm (±10.7 mm, 33-78.9 mm). Inner bone diameter, measured in two axes, was 10.5 mm (±1.3 mm, 5.4-18.7 mm) for the major axis and 7.7 mm (±0.9 mm, 4.3-17.8 mm) for the minor axis. The average cortical thickness was 1.4 mm (±0.3 mm, 0.7-3.1 mm). The distance to the center of the isthmus from the distal end had an average length of 21.3 mm (±1.9 mm, 17-25 mm). CONCLUSIONS: Using these findings a standardized set of intramedullary stems can be developed as a base for a transcutaneous osseointegrated prosthesis, helping to create a reliable method for treating patients with amputated thumbs.

Venlafaxine's therapeutic reference range in the treatment of depression revised: a systematic review and meta-analysis.

INTRODUCTION: The selective serotonin and norepinephrine reuptake inhibitor venlafaxine is among the most prescribed antidepressant drugs worldwide and, according to guidelines, its dose titration should be guided by drug-level monitoring of its active moiety (AM) which consists of venlafaxine (VEN) plus active metabolite O-desmethylvenlafaxine (ODV). This indication of therapeutic drug monitoring (TDM), however, assumes a clear concentration/effect relationship for a drug, which for VEN has not been systematically explored yet. OBJECTIVES: We performed a systematic review and meta-analysis to investigate the relationship between blood levels, efficacy, and adverse reactions in order to suggest an optimal target concentration range for VEN oral formulations for the treatment of depression. METHODS: Four databases (MEDLINE (PubMed), PsycINFO, Web of Science Core Collection, and Cochrane Library) were systematically searched in March 2022 for relevant articles according to a previously published protocol. Reviewers independently screened references and performed data extraction and critical appraisal. RESULTS: High-quality randomized controlled trials investigating concentration/efficacy relationships and studies using a placebo lead-in phase were not found. Sixty-eight articles, consisting mostly of naturalistic TDM studies or small noncontrolled studies, met the eligibility criteria. Of them, five cohort studies reported a positive correlation between blood levels and antidepressant effects after VEN treatment. Our meta-analyses showed (i) higher AM and (ii) higher ODV concentrations in patients responding to VEN treatment when compared to non-responders (n = 360, k = 5). AM concentration-dependent occurrence of tremor was reported in one study. We found a linear relationship between daily dose and AM concentration within guideline recommended doses (75-225 mg/day). The population-based concentration ranges (25-75% interquartile) among 11 studies (n = 3200) using flexible dosing were (i) 225-450 ng/ml for the AM and (ii) 144-302 ng/ml for ODV. One PET study reported an occupancy of 80% serotonin transporters for ODV serum levels above 85 ng/ml. Based on our findings, we propose a therapeutic reference range for AM of 140-600 ng/ml. CONCLUSION: VEN TDM within a range of 140 to 600 ng/ml (AM) will increase the probability of response in nonresponders. A titration within the proposed reference range is recommended in case of non-response at lower drug concentrations as a consequence of VEN's dual mechanism of action via combined serotonin and norepinephrine reuptake inhibition. Drug titration towards higher concentrations will, however, increase the risk for ADRs, in particular with supratherapeutic drug concentrations.

Infection of human alveolar macrophages by human coronavirus strain 229E.

Human coronavirus strain 229E (HCoV-229E) commonly causes upper respiratory tract infections. However, lower respiratory tract infections can occur in some individuals, indicating that cells in the distal lung are susceptible to HCoV-229E. This study determined the virus susceptibility of primary cultures of human alveolar epithelial cells and alveolar macrophages (AMs). Fluorescent antibody staining indicated that HCoV-229E could readily infect AMs, but no evidence was found for infection in differentiated alveolar epithelial type II cells and only a very low level of infection in type II cells transitioning to the type I-like cell phenotype. However, a human bronchial epithelial cell line (16HBE) was readily infected. The innate immune response of AMs to HCoV-229E infection was evaluated for cytokine production and interferon (IFN) gene expression. AMs secreted significant amounts of tumour necrosis factor alpha (TNF-α), regulated on activation normal T-cell expressed and secreted (RANTES/CCL5) and macrophage inflammatory protein 1ß (MIP-1ß/CCL4) in response to HCoV-229E infection, but these cells exhibited no detectable increase in IFN-ß or interleukin-29 in mRNA levels. AMs from smokers had reduced secretion of TNF-α compared with non-smokers in response to HCoV-229E infection. Surfactant protein A (SP-A) and SP-D are part of the innate immune system in the distal lung. Both surfactant proteins bound to HCoV-229E, and pre-treatment of HCoV-229E with SP-A or SP-D inhibited infection of 16HBE cells. In contrast, there was a modest reduction in infection in AMs by SP-A, but not by SP-D. In summary, AMs are an important target for HCoV-229E, and they can mount a pro-inflammatory innate immune response to infection.

Differential requirement for the activation of the inflammasome for processing and release of IL-1beta in monocytes and macrophages.

The processing of pro-interleukin-1beta depends on activation of caspase-1. Controversy has arisen whether Toll-like receptor (TLR) ligands alone can activate caspase-1 for release of interleukin-1beta (IL-1beta). Here we demonstrate that human blood monocytes release processed IL-1beta after a one-time stimulation with either TLR2 or TLR4 ligands, resulting from constitutively activated caspase-1 and release of endogenous adenosine triphosphate. The constitutive activation of caspase-1 depends on the inflammasome components, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and NALP3, but in monocytes caspase-1 activation is uncoupled from pathogen-associated molecular pattern recognition. In contrast, macrophages are unable to process and release IL-1beta solely by TLR ligands and require a second adenosine triphosphate stimulation. We conclude that IL-1beta production is differentially regulated in monocytes and macrophages, and this reflects their separate functions in host defense and inflammation.

Differentiated human alveolar type II cells secrete antiviral IL-29 (IFN-lambda 1) in response to influenza A infection.

Alveolar type II epithelial cells (ATIIs) are one of the primary targets for influenza A pneumonia. The lack of a culture system for maintaining differentiated ATIIs hinders our understanding of pulmonary innate immunity during viral infection. We studied influenza A virus (IAV)-induced innate immune responses in differentiated primary human ATIIs and alveolar macrophages (AMs). Our results indicate that ATIIs, but not AMs, support productive IAV infection. Viral infection elicited strong inflammatory chemokine and cytokine responses in ATIIs, including secretion of IL-8, IL-6, MCP-1, RANTES, and MIP-1beta, but not TNF-alpha, whereas AMs secreted TNF-alpha as well as other cytokines in response to infection. Wild-type virus A/PR/8/34 induced a greater cytokine response than reassortant PR/8 virus, A/Phil/82, despite similar levels of replication. IAV infection increased mRNA expression of IFN genes IFN-beta, IL-29 (IFN-lambda1), and IL-28A (IFN-lambda2). The major IFN protein secreted by type II cells was IL-29 and ATIIs appear to be a major resource for production of IL-29. Administration of IL-29 and IFN-beta before infection significantly reduced the release of infectious viral particles and CXC and CC chemokines. IL-29 treatment of type II cells induced mRNA expression of antiviral genes MX1, OAS, and ISG56 but not IFN-beta. IL-29 induced a dose-dependent decrease of viral nucleoprotein and an increase of antiviral genes but not IFN-beta. These results suggest that IL-29 exerts IFN-beta-independent protection in type II cells through direct activation of antiviral genes during IAV infection.

Salt-sensitive hypertension and reduced fertility in mice lacking the prostaglandin EP2 receptor.

Prostaglandins (PGs) are ubiquitous lipid mediators derived from cyclooxygenase metabolism of arachidonic acid that exert a broad range of physiologic activities, including modulation of inflammation, ovulation and arterial blood pressure. PGE2, a chief cyclooxygenase product, modulates blood pressure and fertility, although the specific G protein-coupled receptors mediating these effects remain poorly defined. To evaluate the physiologic role of the PGE2 EP2 receptor subtype, we created mice with targeted disruption of this gene (EP2-/-). EP2-/- mice develop normally but produce small litters and have slightly elevated baseline systolic blood pressure. In EP2-/- mice, the characteristic hypotensive effect of intravenous PGE2 infusion was absent; PGE2 infusion instead produced hypertension. When fed a diet high in salt, the EP2-/- mice developed profound systolic hypertension, whereas wild-type mice showed no change in systolic blood pressure. Analysis of wild-type and EP2-/- mice on day 5 of pregnancy indicated that the reduced litter size of EP2-/- mice is due to a pre-implantation defect. This reduction of implanted embryos could be accounted for by impaired ovulation and dramatic reductions in fertilization observed on day 2 of pregnancy. These data demonstrate that the EP2 receptor mediates arterial dilatation, salt-sensitive hypertension, and also plays an essential part in female fertility.

Instances of avian osteoarthritis from the Unalaska Sea Ice Project, Unalaska Island, Alaska.

OBJECTIVE: This project is designed to examine the prevalence of skeletal pathology in two archaeological avian bone assemblages. MATERIALS: Archaeological avian bone assemblages with Number of Identified Specimens of 14,909 (UNL-055) and 36,866 (UNL-048). METHODS: Visual examination of humeri, coracoids, tarsometatarsi, and cranial elements for pathology during taxonomic identification. RESULTS: 83 instances of skeletal pathology were observed in these assemblages and were most prevalent in the UNL-048 assemblage. Marginal osteophytes around the articular surfaces of the coracoid were the primary bone pathology in the UNL-048 avian assemblage. CONCLUSIONS: The prevalence of osteoarthritis in surface diving birds at the UNL-048 site could be due to changing climate. SIGNIFICANCE: Considering the environmental factors that contribute to instances of animal pathology allows for a more contextual interpretation of the cultural processes that occurred at archaeological sites. LIMITATIONS: Time and budgetary constraints did not allow for examination of the entire avian assemblage. SUGGESTIONS FOR FUTURE RESEARCH: Further intensive review of archaeological avian assemblages alongside consideration of environmental and cultural processes occurring during the site occupation is advised.

The impact of tinnitus distress on cognition.

Tinnitus is the chronic perception of a phantom sound with different levels of related distress. Past research has elucidated interactions of tinnitus distress with audiological, affective and further clinical variables. The influence of tinnitus distress on cognition is underinvestigated. Our study aims at investigating specific influences of tinnitus distress and further associated predictors on cognition in a cohort of n = 146 out-ward clinical tinnitus patients. Age, educational level, hearing loss, Tinnitus Questionnaire (TQ) score, tinnitus duration, speech in noise (SIN), stress, anxiety and depression, and psychological well-being were included as predictors of a machine learning regression approach (elastic net) in three models with scores of a multiple choice vocabulary test (MWT-B), or two trail-making tests (TMT-A and TMT-B), as dependent variables. TQ scores predicted lower MWT-B scores and higher TMT-B test completion time. Stress, emotional, and psychological variables were not found to be relevant predictors in all models with the exception of small positive influences of SIN and depression on TMT-B. Effect sizes were small to medium for all models and predictors. Results are indicative of specific influence of tinnitus distress on cognitive performance, especially on general or crystallized intelligence and executive functions. More research is needed at the delicate intersection of tinnitus distress and cognitive skills needed in daily functioning.

Why predict climate hazards if we need to understand impacts? Putting humans back into the drought equation.

Virtually all climate monitoring and forecasting efforts concentrate on hazards rather than on impacts, while the latter are a priority for planning emergency activities and for the evaluation of mitigation strategies. Effective disaster risk management strategies need to consider the prevailing "human terrain" to predict who is at risk and how communities will be affected. There has been little effort to align the spatiotemporal granularity of socioeconomic assessments with the granularity of weather or climate monitoring. The lack of a high-resolution socioeconomic baseline leaves methodical approaches like machine learning virtually untapped for pattern recognition of extreme climate impacts on livelihood conditions. While the request for "better" socioeconomic data is not new, we highlight the need to collect and analyze environmental and socioeconomic data together and discuss novel strategies for coordinated data collection via mobile technologies from a drought risk management perspective. A better temporal, spatial, and contextual understanding of socioeconomic impacts of extreme climate conditions will help to establish complex causal pathways and quantitative proof about climate-attributable livelihood impacts. Such considerations are particularly important in the context of the latest big data-driven initiatives, such as the World Bank's Famine Action Mechanism (FAM).

Rat respiratory coronavirus infection: replication in airway and alveolar epithelial cells and the innate immune response.

The rat coronavirus sialodacryoadenitis virus (SDAV) causes respiratory infection and provides a system for investigating respiratory coronaviruses in a natural host. A viral suspension in the form of a microspray aerosol was delivered by intratracheal instillation into the distal lung of 6-8-week-old Fischer 344 rats. SDAV inoculation produced a 7 % body weight loss over a 5 day period that was followed by recovery over the next 7 days. SDAV caused focal lesions in the lung, which were most severe on day 4 post-inoculation (p.i.). Immunofluorescent staining showed that four cell types supported SDAV virus replication in the lower respiratory tract, namely Clara cells, ciliated cells in the bronchial airway and alveolar type I and type II cells in the lung parenchyma. In bronchial alveolar lavage fluid (BALF) a neutrophil influx increased the population of neutrophils to 45 % compared with 6 % of the cells in control samples on day 2 after mock inoculation. Virus infection induced an increase in surfactant protein SP-D levels in BALF of infected rats on days 4 and 8 p.i. that subsided by day 12. The concentrations of chemokines MCP-1, LIX and CINC-1 in BALF increased on day 4 p.i., but returned to control levels by day 8. Intratracheal instillation of rats with SDAV coronavirus caused an acute, self-limited infection that is a useful model for studying the early events of the innate immune response to respiratory coronavirus infections in lungs of the natural virus host.

Prostaglandins and leukotrienes: advances in eicosanoid biology.

Prostaglandins and leukotrienes are potent eicosanoid lipid mediators derived from phospholipase-released arachidonic acid that are involved in numerous homeostatic biological functions and inflammation. They are generated by cyclooxygenase isozymes and 5-lipoxygenase, respectively, and their biosynthesis and actions are blocked by clinically relevant nonsteroidal anti-inflammatory drugs, the newer generation coxibs (selective inhibitors of cyclooxygenase-2), and leukotriene modifiers. The prime mode of prostaglandin and leukotriene action is through specific G protein-coupled receptors, many of which have been cloned recently, thus enabling specific receptor agonist and antagonist development. Important insights into the mechanisms of inflammatory responses, pain, and fever have been gleaned from our current understanding of eicosanoid biology.

Resistance to type 1 diabetes induction in 12-lipoxygenase knockout mice.

Leukocyte 12-lipoxygenase (12-LO) gene expression in pancreatic beta cells is upregulated by cytotoxic cytokines like IL-1beta. Recent studies have demonstrated that 12-LO inhibitors can prevent glutamate-induced neuronal cell death when intracellular glutathione stores are depleted. Therefore, 12-LO pathway inhibition may prevent beta-cell cytotoxicity. To evaluate the role of 12-LO gene expression in immune-mediated islet destruction, we used 12-LO knockout (12-LO KO) mice. Male homozygous 12-LO KO mice and control C57BL/6 mice received 5 consecutive daily injections of low-dose streptozotocin to induce immune-mediated diabetes. Fasting serum glucose and insulin levels were measured at 7-day intervals, and the mice were followed up for 28 days. 12-LO KO mice were highly resistant to diabetes development compared with control mice and had higher serum insulin levels on day 28. Isolated pancreatic islets were treated with IL-1beta, TNF-alpha, and IFN-gamma for 18 hours. Glucose-stimulated insulin secretion in cytokine-treated islets from C57/BL6 mice decreased 54% from that of untreated islets. In marked contrast, the same cytokine mix led to only a 26% decrease in islets from 12-LO KO mice. Furthermore, cytokine-induced 12-hydroxyeicosatetraenoic acid (12-HETE) production was absent in 12-LO KO islets but present in C57/BL6 islets. Isolated peritoneal macrophages were stimulated for 48 hours with IFN-gamma + LPS and compared for nitrate/nitrite generation. 12-LO KO macrophages generated 50% less nitrate/nitrite when compared with C57BL/6 macrophages. In summary, elimination of leukocyte 12-LO in mice ameliorates low dose streptozotocin-induced diabetes by increasing islet resistance to cytokines and decreasing macrophage production of nitric oxide.

Disruption of the 12/15-lipoxygenase gene diminishes atherosclerosis in apo E-deficient mice.

Atherosclerosis may be viewed as an inflammatory disease process that includes early oxidative modification of LDLs, leading to foam cell formation. This "oxidation hypothesis" has gained general acceptance in recent years, and evidence for the role of lipoxygenases in initiation of, or participation in, the oxidative process is accumulating. However, the relative contribution of macrophage-expressed lipoxygenases to atherogenesis in vivo remains unknown. Here, we provide in vivo evidence for the role of 12/15-lipoxygenase in atherogenesis and demonstrate diminished plasma IgG autoantibodies to oxidized LDL epitopes in 12/15-lipoxygenase knockout mice crossbred with atherosclerosis-prone apo E-deficient mice (apo E-/-/L-12LO-/-). In chow-fed 15-week-old apo E-/-/L-12LO-/- mice, the extent of lesions in whole-aorta en face preparations (198 +/- 60 microm2) was strongly reduced (P < 0.001, n = 12) when compared with 12/15-lipoxygenase-expressing controls (apo E-/-/L-12LO+/+), which showed areas of lipid deposition (15,700 +/- 2,688 microm2) in the lesser curvature of the aortic arch, branch points, and in the abdominal aorta. These results were observed despite cholesterol, triglyceride, and lipoprotein levels that were similar to those in apo E-deficient mice. Evidence for reduced lesion development was observed even at 1 year of age in apo E-/-/L-12LO-/- mice. The combined data indicate a role for 12/15-lipoxygenase in the pathogenesis of atherosclerosis and suggest that inhibition of this enzyme may decrease disease progression.

Role of wireless motility capsule in the assessment and management of gastrointestinal dysmotility in patients with diabetes mellitus.

BACKGROUND: Gastrointestinal (GI) dysmotility is common in diabetic patients. Wireless Motility Capsule (WMC) provides the transit profile of the entire GI tract in a single study. Factors affecting GI dysmotility and utility of WMC study are not clearly established in diabetic patients. Our aims were to study the pattern of GI dysmotility using WMC and evaluate the effect of glycemic control and presence of diabetic microvascular complications on motility impairment in diabetic patients. We also assessed the impact of WMC findings on clinical management. METHODS: Retrospective chart review of all diabetic patients who underwent WMC testing at our institution from 2010 to 2015 was performed. Demographics, hemoglobinA1c levels, microvascular complications, and WMC findings were obtained. Impact of WMC on clinical management was assessed. KEY RESULTS: A total of 100 patients were included. Mean age was 45±19 years and 76% were female. Seventy-two percentage had abnormal WMC testing, of which 29 (40%) had multiregional dysmotility. There were no significant differences in demographics, diabetic microvascular complications or hemoglobinA1c levels among patients with normal and abnormal WMC testing or among patients with isolated vs multiregional dysmotility. Information about subsequent clinical management was available for 47 patients. WMC testing was abnormal in 33 (70%) patients and treatment changes based on WMC results were made in 24 patients (73%). CONCLUSIONS & INFERENCES: There was no association between hemoglobinA1c levels, microvascular complications and pattern of GI dysmotility in diabetic patients undergoing WMC. WMC testing lead to management changes in approximately 75% of diabetic patients with GI dysmotility.

Inhibition of human melanoma growth by prostaglandin A, D, and J analogues.

The relative inhibitory potency of prostaglandin A (PGA) and prostaglandin J2 (PGJ2) analogues compared to prostaglandin A1 (PGA1) was determined in a clonogenic assay system. Three human melanoma cell strains (C8146A, C8146C, and C8161), a human melanoma cell line (M1RW5) and a human neuroblastoma cell line (IMR-32) were used. Prostaglandin analogues were screened in the clonogenic assay system and the dose effect curves were analyzed by linear regression utilizing the median effect relationship. The computer-generated 50% and 95% inhibitory doses showed that 15-deoxy-16-hydroxyl-16-vinyl-prostaglandin A2 (DHV-PGA2) was from two- to three-fold more active than PGA1 in inhibiting the clonogenic growth of human melanoma cells. Based on the 50% inhibitory dose, PGJ2 and its analogues were from two to five times more potent than PGA1. The delta 12- and delta 12,14-PGJ2 were the most potent of the prostaglandins tested. However, the 95% inhibitory dose for prostaglandin D2 (PGD2), PGJ2 and its analogues against neuroblastoma did not show any enhancement in activity in comparison to PGA1, suggesting that some tumor specificity in the activity of these analogues may be signified by the neuroblastoma data. Prostaglandins which contained a fluoride substitution at position 11 were also tested for activity. As we previously observed with other analogues which did not contain an alpha, beta-unsaturated carbonyl group in the cyclopentane ring, 9 beta, 15 alpha-dihydroxy-11 beta-fluoroprosta-5-cis-13-trans-dienoic acid and 9 alpha, 15 alpha-dihydroxy-11 beta-fluoroprosta-5-cis-13-trans-dienoic acid did not inhibit the clonogenic growth of human melanoma cells. Administration s.c. to established human melanoma tumors growing in athymic nude mice caused a significant growth inhibition. The treatment schedules ranged from 1 to 8 days. Injection s.c. of PGA1 at a dose of 40 mg/kg/day resulted in a 20% suppression in tumor growth. Higher doses (100 and 200 mg/kg/day) effected an 80% reduction in tumor growth. The higher doses were associated with reversible toxicities, diarrhea and skin inflammation. Administration of DHV-PGA2 at a dose of 20 mg/kg/day resulted in 40% reduction in tumor growth. The increased in vivo potency of DHV-PGA2 corresponds to the results obtained in the clonogenic assay system.

The Complete Genome Sequence of Plodia Interpunctella Granulovirus: Evidence for Horizontal Gene Transfer and Discovery of an Unusual Inhibitor-of-Apoptosis Gene.

The Indianmeal moth, Plodia interpunctella (Lepidoptera: Pyralidae), is a common pest of stored goods with a worldwide distribution. The complete genome sequence for a larval pathogen of this moth, the baculovirus Plodia interpunctella granulovirus (PiGV), was determined by next-generation sequencing. The PiGV genome was found to be 112, 536 bp in length with a 44.2% G+C nucleotide distribution. A total of 123 open reading frames (ORFs) and seven homologous regions (hrs) were identified and annotated. Phylogenetic inference using concatenated alignments of 36 baculovirus core genes placed PiGV in the "b" clade of viruses from genus Betabaculovirus with a branch length suggesting that PiGV represents a distinct betabaculovirus species. In addition to the baculovirus core genes and orthologues of other genes found in other betabaculovirus genomes, the PiGV genome sequence contained orthologues of the bidensovirus NS3 gene, as well as ORFs that occur in alphabaculoviruses but not betabaculoviruses. While PiGV contained an orthologue of inhibitor of apoptosis-5 (iap-5), an orthologue of inhibitor of apoptosis-3 (iap-3) was not present. Instead, the PiGV sequence contained an ORF (PiGV ORF81) encoding an IAP homologue with sequence similarity to insect cellular IAPs, but not to viral IAPs. Phylogenetic analysis of baculovirus and insect IAP amino acid sequences suggested that the baculovirus IAP-3 genes and the PiGV ORF81 IAP homologue represent different lineages arising from more than one acquisition event. The presence of genes from other sources in the PiGV genome highlights the extent to which baculovirus gene content is shaped by horizontal gene transfer.

Metabolism of linoleic acid by prostaglandin endoperoxide synthase from adult and fetal blood vessels.

Linoleic acid (18:2) is converted by prostaglandin endoperoxide synthase in particulate fractions and homogenates of fetal calf aorta to its 9- and 13-hydroperoxy metabolites. These intermediates are then either dehydrated to the corresponding oxo compounds or reduced to monohydroxy products. Alternatively, the hydroperoxyoctadecadienoic acids can be converted to epoxyhydroxyoctadecenoic acids, which are hydrolyzed to trihydroxy metabolites by epoxide hydrolases present in both particulate and cytosolic fractions from aorta. Linoleic acid (Km, 442 microM) is a much poorer substrate for prostaglandin endoperoxide synthase than is arachidonic acid (20:4) (Km, 48 microM). However, the oxygenation of 18:2 by particulate fractions from aorta is linear with time for at least 5 min, whereas the oxygenation of 20:4 is linear for only 15 s. Arachidonic acid strongly inhibits the conversion of 18:2 to monohydroxy (ID50, 10 microM) and trihydroxy (ID50, 140 microM) products. Linoleic acid has a similar, but much weaker effect on the formation of 6-oxoprostaglandin F1 alpha from 20:4. Substantial amounts of both the monohydroxy (9-hydroxy-10, 12-octadecadienoic acid and 13-hydroxy-9,11-octadecadienoic acid) and trihydroxy (9,10,11-trihydroxy-12-octadecenoic acid, 9,10,13-trihydroxy-11-octadecenoic acid and 9,12,13-trihydroxy-10-octadecenoic acid) metabolites of 18:2 were shown by gas chromatography-mass spectrometry to be formed from endogenous substrate during incubation of slices of fetal calf aorta in physiological medium. This raises the possibility that some of these products or their hydroperoxy precursors may have some biological significance.

Effects of selenium-deficient diets on the production of prostaglandins and other oxygenated metabolites of arachidonic acid and linoleic acid by rat and rabbit aortae.

Selenium is an essential component of glutathione peroxidase, which reduces free and esterified hydroperoxides of polyunsaturated fatty acids. Adequate glutathione peroxidase activity could be important for the maintenance of prostacyclin synthesis by blood vessels, since hydroperoxides can inhibit the formation of this substance. We have investigated the effects of dietary selenium deficiency on glutathione peroxidase activity and the synthesis of 6-oxoprostaglandin F1 alpha and monohydroxy and trihydroxy metabolites of polyunsaturated fatty acids by aorta. The latter products can be formed either by the actions of cyclooxygenase or lipoxygenase or by lipid peroxidation. Aortic glutathione peroxidase activity was reduced by over 80% by feeding rats a selenium-deficient diet for 4 weeks, and to undetectable levels after 6 weeks. There were no appreciable differences in the levels of free and esterified oxygenated metabolites of linoleic acid or arachidonic acid between the control and treated groups after 4 weeks. However, after 6 weeks, there were modest, but statistically significant reductions in the formation of 6-oxoprostaglandin F1 alpha and monohydroxy products formed by cyclooxygenase. On the other hand, the amounts of esterified 18:2 metabolites appeared to be higher in aortae from animals on the selenium-deficient diet, although only the increase in esterified 9-hydroxy-10,12-octadecadienoic acid was statistically significant. These results suggest that selenium deficiency can affect the formation of prostacyclin and other oxygenated metabolites of polyunsaturated fatty acids by aorta, possibly by increasing lipid peroxidation. However, the differences between control and selenium-deficient rats after 6 weeks were not very dramatic, in spite of the fact that glutathione peroxidase activity was undetectable. It would therefore appear that additional mechanisms are also involved in controlling the levels of lipid hydroperoxides in aorta.

Binding of prostaglandin E2 to cultured bovine adrenal chromaffin cells and its effect on catecholamine secretion.

We have previously shown that plasma membranes from adrenal medulla possess specific high-affinity binding sites for prostaglandins (PGs) E1 and E2. We have now investigated the binding of PGE2 to intact bovine adrenal chromaffin cells and the effects of prostaglandins on the release of catecholamines from these cells. Adrenal chromaffin cells specifically bound PGE2 with a dissociation constant of 2 nM and a concentration of about 40,000 binding sites per cell. Low concentrations of PGE2 inhibited the nicotine-stimulated release of catecholamines from these cells. The effect of PGE2 was biphasic, the maximal inhibitory effect being observed at a concentration of between 1 and 10 nM. Higher concentrations (1 microM) of PGE2 had minimal inhibitory effects on nicotine-evoked noradrenaline release, but instead had a direct stimulatory effect in the absence of cholinergic agonists. Although the stimulatory effects of high concentrations of PGE2 were reproducibly observed in all cell preparations, only about one-half of the cultures tested responded to the inhibitory effects of this prostaglandin. It is possible that PGE2 plays a modulatory role in the regulation of catecholamine secretion from the adrenal medulla.

Lipoxin generation by human megakaryocyte-induced 12-lipoxygenase.

Eicosanoid biosynthesis was examined with a human megakaryocytic cell line (Dami). Megakaryocytes incubated with [1-14C]arachidonic acid and either ionophore A23187 or thrombin generated both thromboxane and 12-hydroxyheptadecatrienoic acid (HHTrE). Exposure to phorbol myristate acetate (PMA) for 1 through 9 days induced differentiation and revealed an increase in the conversion of [1-14C]arachidonate to cyclooxygenase- and lipoxygenase (LO)-derived products. The LO-derived product was identified as 12S-HETE by its physical characteristics including GC/MS and chiral column SP-HPLC. PMA-treated Dami cells did not generate 5-HETE, leukotrienes or lipoxins from exogenous arachidonic acid while they did convert leukotriene A4 (LTA4) to lipoxin A4, lipoxin B4 and their respective all-trans isomers. In addition, COS-M6 cells transfected with a human 12-lipoxygenase cDNA and incubated with either arachidonic acid or LTA4 generated 12-HETE and lipoxins, respectively. The lipoxin profile generated by transfected COS-M6 cells incubated with LTA4 was similar to that generated by the PMA-treated Dami cells. Results indicate that human megakaryocytes can transform arachidonate and LTA4 to bioactive eicosanoids and that the 12-lipoxygenase appears upon further differentiation of these cells. In addition, they indicate that the 12-LO of human megakaryocytes and the 12-LO expressed by transfected COS cells can generate both lipoxins A4 and B4. Together they suggest that the human 12-LO can serve as a model of LX-synthetase activity with LTA4.