Sacubitril valsartan in aged patients with heart failure and reduced ejection fraction: a safe and beneficial therapy

Background

Heart failure (HF) constitutes a prevalent diagnosis in aged patients. During the last decades, several therapies have demonstrated clinical benefits among patients with HF and left ventricular systolic disfunction (LVSD), including novel angiotensin receptor-neprylisin inhibitors (ARNI). Nevertheless, these findings remain unclear in the elderly.

Purpose

The objective of this study is the evaluation of ARNI treatment in aged patients with HF and reduced left ventricular ejection fraction (LVEF)..

Methods

Patients were prospectively recruited from January 2016 to December 2020. Subjects LVSD (defined by LVEF below 40%), aged ≥75 years and indication for ARNI were included. Clinical, electrocardiographic and echocardiographic variables were collected.

Results

A total of 616 patients were included in the present study. Median age was 83.3 years old (standard deviation, SD, ± 5.1) and 65.6% were male. 81.2% had hypertension, 35.4% diabetes, and 57.1% dyslipemia. Chronic kidney disease was present in up to 53.6% of the patients; 17.8% suffered from chronic lung disease and 16.2% from cerebrovascular disease. At baseline, the mean LVEF was 29.3% (SD ± 7.7%), being the ischemic disease the most common etiology, with 46.6% of the cases. 60.0% of the patients had sinus rhythm on ECG at inclusion. Nearly 45.0% of the patients had been hospitalized before the recruitment due to heart failure. 77% of the patients had BB in their treatment; 55% had ACEIs / ARBs; 40% had MRA; 4% had iSGLT2. The percentage of patients with ARNI was 14.3%. The median follow-up was 35 months; in this time, 50.2% died; cardiovascular events (dead for any cause or new admission secondary to heart failure) were reported in 62.2% of the patients. A multivariate survival study was performed, using Cox regression. It showed that the use of ARNI in this population represent a powerful protective factor against mortality (HR 0.268; 95% CI 0.162–0.443).

Conclusion

In our study, it has been shown that ARNI improved survival in aged subjects with HF and LVSD. However, this drug is underuse in this population. This may be related to frailty, greater comorbidity and the polypharmacy that lead to lesser accomplishment of clinical guidelines recommendations. However, it would be recommendable to confirm our findings with further studies.

Funding Acknowledgement

Type of funding sources: None.

Outcomes of sodium-glucose co-transporter type 2 inhibitors use in elderly patients with heart failure with reduced ejection fraction

Background

Heart failure is a highly prevalent condition, especially in patients over 75 years. In recent years, new therapeutic lines have emerged for the management of heart failure with reduced ejection fraction (HFrEF), most notably sodium-glucose co-transporter type 2 inhibitors (iSGLT2). However, there are currently low evidence of the benefit in this subgroup.

Methods

A retrospective study was conducted from January 2016 to December 2020 in our hospital. All patients aged ≥75 years, diagnosed with HFrEF (defined by left ventricular ejection fraction <40%), and current guidelines recommendations for iSGLT2 were included. Clinical, electrocardiographic and echocardiographic data were collected.

Results

A total of 616 patients were included, with a mean age at the inclusion of 83.3 years (standard deviation, SD, ± 5); 65.6% of the patients included were male. 81.2% were hypertensive, 35.4% were diabetic. 46.2% had chronic kidney disease (defined as glomerular filtrate <60mL/min/1.73 m2). Chronic lung disease was present in 14.8% of the patients, 16.2% had a history of cerebrovascular events and 12.7% suffered from peripheral vascular disease. The most frequent cause of HFrEF was ischemic, with 53.9%. A total of 86.8% presented a NYHA I-II; in 60.3% of the subjects, the rhythm at inclusion was sinus rhythm. The percentage of patients with BB was 76.9%, with ACEI / ARB 69.8%, 14.3% with ARNI and with anti-aldosterone agents 40.4%. The percentage of patients with SGLT2i was only 4.2%. The median follow-up was 34.5 months, during which 50.4% of the population died and 62.5% had a cardiovascular event (death or hospitalization for heart failure). A survival analysis using Cox regression showed that SGLT2i in this subgroup of patients was a protective factor against mortality (HR 0.124; 95% CI 0.031–0.497) and cardiovascular events (HR 0.428; 95% CI 0.221–0.830)

Conclusion

Despite current recommendations in the guidelines, there is marked underuse in elderly patients of SGLT2i. This could be related to greater intolerance or contraindication, but also to a lesser application of the clinical evidence in this population group. However, the use of SGLT2i has been shown as a significant factor associated with improved survival and comorbidity rate in our study population.

Funding Acknowledgement

Type of funding sources: None.

Clinical factors associated with microvascular obstruction in early presenters of ST-segment elevation myocardial infarction

Background

Microvascular obstruction (MVO) is a phenomenon that occurs frequently even after primary coronary intervention with recanalization of the infarct-related artery (IRA) and it has been shown to increase the risk of adverse cardiovascular events in ST-segment elevation myocardial infarction (STEMI) patients. The most important clinical predictor of MVO is ischemia duration, but there is a lack of information regarding predictor factors in promptly revascularized patients.

Methods

From January 2007 to October 2017, 987 patients with STEMI that underwent urgent coronary angiography were retrospectively enlisted. We included 321 patients that were revascularized in ≤3 hours from symptom onset. Clinical and angiographic data were taken from hospital records. A univariate and multivariate Cox regression analysis was made to assess the relationship between MVO (defined as final TIMI <3 in IRA) and potential predictors.

Results

From the 321 patients included, 76.9% were male and the mean age was 63.6±13.4 years. LVEF at admission was 46.2±12%. The mean time between symptom onset and wire crossing was 2.2±0.6 hours and MVO was found in 43 cases (13.4%). Descriptive data of predictor factors and their association with MVO are shown in Table 1. After the multivariate Cox regression analysis, smoking was a protector factor of MVO (OR 0.39 [0.16–0.96]). Age (OR 1.03 [1.01–1.06]) and Killip class III-IV at admission (OR 5.96 [2.1–16.4]) were directly associated with MVO. No other clinical variables were independently associated with the occurrence of MVO.

Conclusions

In very early presenters of STEMI, age and Killip class III-IV at admission were clinical predictor factors of MVO. Current smoking could carry a protector mechanism for MVO in this population, that is yet to be confirmed with prospective studies.

Funding Acknowledgement

Type of funding source: None

P4614Predictor factors of microvascular obstruction in early presenters of ST-segment elevation myocardial infarction

Background

Microvascular obstruction (MVO) is a phenomenon that occurs frequently even after primary coronary intervention with recanalization of the infarct-related artery (IRA) and it has been shown to increase the risk of adverse cardiovascular events in ST-segment elevation myocardial infarction (STEMI) patients. The most important clinical predictor of MVO is ischemia duration, but there is a lack of information regarding predictor factors in promptly revascularized patients.

Methods

From January 2007 to October 2017, 1022 patients with STEMI that underwent urgent coronary angiography were retrospectively enlisted. We included 760 patients that were revascularized in ≤6 hours from symptom onset. Clinical, echocardiographic and angiographic data were taken from hospital records. A multivariate Cox regression analysis was made to assess the relationship between MVO (defined as final TIMI <3 in IRA) and potential predictors.

Results

From the 760 patients included, 73.7% were male and the mean age was 64.8±14.2 years. LVEF at admission was 46.1±12% and Killip class at admission was III-IV in 12.8% of the cases. The mean time between symptom onset and wire crossing was 3.3±1.3 hours. MVO was found in 130 cases (17.2%). After the multivariate Cox regression analysis, Killip class III-IV at admission was associated with MVO (OR 2.87 [1.31–6.31]). No other clinical variables were independently associated with the occurrence of MVO. The angiographic and interventional variables with a significant association with MVO were: predilatation (OR 1.87 [1.003–3.49]), postdilatation (OR 0.49 [0.27–0.89]), stent length (OR 1.04 [1.001–1.08]), stent diameter (OR 1.89 [1.11–3.23]), thrombus burden of the culprit lesion (OR 2.69 [1.26–5.71]) and distal embolization (OR 5.52 [2.79–10.89]).

Conclusions

In early presenters of STEMI, angiographic and interventional variables were more important as predictors of MVO than clinical variables. Killip class III-IV at admission was a clinical predictor factor for MVO in this population. Prospective studies are needed to confirm these results.

P4617Early electrocardiographic changes as markers of coronary microvascular obstruction in acute myocardial infarction with ST segment elevation

Background

Coronary microvascular obstruction (CMVO), occurs frequently even after a quickly epicardial revascularization of the infarct-related artery (IRA), and has been associated with an increased risk of adverse cardiovascular events and poor prognosis in patients with ST-segment myocardial infarction (STEMI). After primary coronary intervention (PCI), incomplete ST-segment elevation (STE) resolution in the ECG has been related to CMVO and worse clinical outcome. However, there is lack of information regarding other ECG changes. The aim of this study is to describe the initial ECG changes in STEMI and evaluate their association with CMVO.

Methods

From January 2007 to December 2017, all patients with the diagnosis of STEMI that underwent urgent coronary angiography were retrospectively included. Clinical, echocardiographic, and electrocardiographic data were taken from medical records. A univariate and multivariate analysis was performed to evaluate the relationship between initial ECG changes (before PCI) and CMVO defined as final TIMI <3 in the IRA.

Results

1022 patients were included; the mean age was 67.8 years (±14), 73.7% were male and 14.4% had previous coronary artery disease. The most frequent IRA was the anterior descending artery in 43.2% of the cases and CMVO was found in 18.3% of the patients. The mean value of STE sum (defined as the sum of STE in V1-V6, I and aVL in anterior STEMI and the sum of II, III, aVF, V5 and V6 in non-anterior STEMI), maximum STE in one lead and number of leads with STE was 11.36mm (± 8.2), 3.65mm (± 2.3) and 4.14mm (± 1.4), respectively. After a univariate analysis, STE sum, maximum STE in one lead and number of leads with STE were associated with CMVO, while only STE sum remained significantly associated with the presence of CMVO after a multivariate analysis (Table). The resolution of STE in the first 2 hours after PCI was a protector factor for CMVO.

Univariate and Multivariate Analysis Univariate Multivariate Variables OR 95% CI p OR IC 95% p Sum of STE 1.03 1.01–1.04 0.013 1.03 1.01–1.05 0.005 Number of leads with STE 1.13 1.02–1.26 0.021 1.04 0.87–1.23 0.67 Maximum STE 1.09 1.02–1.16 0.016 1.04 0.92–1.17 0.49 Resolution of STE 0.35 0.25–0.49 <0.001 0.36 0.25–1.18 <0.001 STE, ST-segment elevation.

Conclusion

Initial ECG changes such as STE sum, number of leads with STE and maximum STE in one lead can be used as early predictors of CMVO and poor prognosis. STE resolution in the first 2 hour was associated with a lower incidence of CMVO as reported in previous studies.

Acknowledgement/Funding

None

Effects of chronic treatment with corticosterone and imipramine on fos immunoreactivity and adult hippocampal neurogenesis

In a previous study we showed that rats chronically treated with corticosterone (CORT) display anxiogenic behavior, evidenced by facilitation of avoidance responses in the elevated T-maze (ETM) model of anxiety. Treatment with the tricyclic antidepressant imipramine significantly reversed the anxiogenic effects of CORT, while inhibiting ETM escape, a response related to panic disorder. To better understand the neurobiological mechanisms underlying these behavioral effects, analysis of c-fos protein immunoreactivity (fos-ir) was used here to map areas activated by chronic CORT (200 mg pellets, 21-day release) and imipramine (15 mg/kg, IP) administration. We also evaluated the number of cells expressing the neurogenesis marker doublecortin (DCX) in the hippocampus and measured plasma CORT levels on the 21st day of treatment. Results showed that CORT increased fos-ir in the ventrolateral septum, medial amygdala and paraventricular hypothalamic nucleus and decreased fos-ir in the lateral periaqueductal gray. Imipramine, on the other hand, increased fos-ir in the medial amygdala and decreased fos-ir in the anterior hypothalamus. CORT also decreased the number of DCX-positive cells in the ventral and dorsal hippocampus, an effect antagonized by imipramine. CORT levels were significantly higher after treatment. These data suggest that the behavioral effects of CORT and imipramine are mediated through specific, at times overlapping, neuronal circuits, which might be of relevance to a better understanding of the physiopathology of generalized anxiety and panic disorder.

A comparison between cervical dimensions of pregnant and nonpregnant Santa Gertrudis and Bos taurus cows

Cervical measurements were recorded on palpation per rectum for 603 Bos taurus , Santa Gertrudis, and crossbred cattle. Postmortem cervical measurements were recorded for 77 of these cows. Antemortem measurements were positively correlated with those taken at postmortem examination (cervical diameter: r=0.75, P<0.01 and cervical length: r=0.29, P<0.06). Cervical diameters from antemortem and postmortem specimens were greater in Santa Gertrudis cattle than in Bos taurus and crossbred cattle (P<0.05). Cervical shape was different between Santa Gertrudis cattle and Bos taurus or crossbred cattle (P<0.01), with Santa Gertrudis cows having a higher incidence of conical shaped cervices than other breeds. Within Santa Gertrudis cattle, the incidence of conical cervical shape increased with age (P<0.05). Conical cervical shape was associated with a lower pregnancy rate in all breeds (P<0.01). Within Santa Gertrudis cattle, conical cervical shape was associated with a lower pregnancy rate in 1- to 4-year-old cows (P<0.05) but not in cows more than 4 years of age (P>0.05).

Acute restraint differently alters defensive responses and fos immunoreactivity in the rat brain

Results from a previous study show that rats exposed to acute restraint display anxiogenic-like behavior, evidenced by facilitation of avoidance responses in the elevated T-maze (ETM) model of anxiety. In contrast, escape responses were unaltered by stress exposure. Since ETM avoidance and escape tasks seem to activate distinct sets of brain structures, it is possible that the differences observed with acute restraint are due to particularities in the neurobiological mechanisms which modulate these responses. In the present study, analysis of fos protein immunoreactivity (fos-ir) was used to map areas activated by exposure of male Wistar rats to restraint stress (30 min) previously (30 min) to the ETM. Corticosterone levels were also measured in stressed and non-stressed animals. Confirming previous observations restraint facilitated avoidance performance, an anxiogenic result, while leaving escape unaltered. Performance of the avoidance task increased fos-ir in the frontal cortex, intermediate lateral septum, basolateral amygdala, basomedial amygdala, lateral amygdala, anterior hypothalamus and dorsal raphe nucleus. In contrast, performance of escape increased fos-ir in the ventromedial hypothalamus, dorsolateral periaqueductal gray and locus ceruleus. Both behavioral tasks also increased fos-ir in the dorsomedial hypothalamus. Restraint significantly raised corticosterone levels. Additionally after restraint, fos-ir was predominantly seen in the basolateral amygdala and dorsal raphe of animals submitted to the avoidance task. This data confirms that different sets of brain structures are activated by ETM avoidance and escape tasks and suggests that acute restraint differently alters ETM behavior and the pattern of fos activation in the brain.

Salivary cortisol, stress, and health in primary caregivers (mothers) of children with cerebral palsy

This study evaluated level of salivary cortisol and perceived burden, stress and health of mothers and primary caregivers of children (4-11 years of age) with cerebral palsy (purpose group, n=37) and those for mothers of children of the same age without developmental problems (control group, n=38). Anthropometric and socioeconomic data were collected from the participants, who also completed the perceived stress questionnaire, the Burden Interview and the 36-Item Short Form Health Survey (SF-36). Cortisol level was assayed in saliva samples collected at various times in a single day and the area under the cortisol curve was then determined. Both groups presented low socioeconomic level and high, although equivalent, perceived stress index. However, the purpose group showed lower cortisol levels, as well as lower scores for many of the SF-36 domains related to physical well-being (physical functioning, role-physical, vitality, and general health) and social functioning. Nevertheless, bodily pain was also reported to be lower. For the control group, the area under the cortisol curve correlated negatively with mental health and social functioning. For the purpose group, where the burden is greater, no such correlation was found. It was concluded that mothers of healthy children leaving in unfavorable socioeconomic conditions face high levels of stress with the hypothalamus-pituitary-adrenal cortex axis function preserved. However, to the mothers of children with cerebral palsy, who live in even worse socioeconomic conditions and also have the burden of caring for a disabled child, the level of stress was overwhelming, to an extent that it impaired the hypothalamus-pituitary-adrenal cortex axis function, as well as reflecting negatively on certain aspects of their physical and psychological well-being. This must receive consideration during the treatment of the child, an approach which is in line with present day tendencies towards family-centered models of assistance to disabled children.

Enhanced solid-liquid separation of dairy manure with natural flocculants

The aim of this study was to determine the effectiveness of natural flocculants to reduce solids and nutrient loads in dairy cow wastewater using solid-liquid separation; chitosan was used as a model. Its use efficiency and optimum application rate were determined using flushed dairy cow manure of varied strengths - 0.4%, 0.8%, 1.6%, and 3.2% total solids (TS) content. Treatments consisted of nine rates of chitosan. The flocculated manure was dewatered using 1-mm and 0.25-mm screens. Separation by screening alone was not effective; average efficiencies were about 60% for total suspended solids (TSS), 22% for total Kjeldahl nitrogen (TKN), and 26% for total phosphorus (TP). Mixing with chitosan before screening substantially increased separation. At optimum chitosan rate (0.5g/L for the highest strength effluent), separation efficiencies were >95% for TSS, >73% for TKN, and >54% for TP. The results of this study indicate that natural flocculants such as chitosan are useful for the solid-liquid separation treatment of livestock wastewater.

Salivary cortisol concentrations, stress and quality of life in women with endometriosis and chronic pelvic pain

The objective of this study was to evaluate the perceived stress index, quality of life, and hypothalamus-pituitary-adrenal axis activity in women with endometriosis and chronic pelvic pain. For the study, 93 women with endometriosis and 82 healthy women volunteered. The visual analogue scale (VAS) (0=no pain; 10=severe pain) was used to determine pain intensity; the perceived stress questionnaire (PSQ) defined stress index, and the health-related quality-of-life (HRQOL)-SF-36 questionnaire was used to evaluate quality of life. Salivary cortisol was measured at 0800, 1600, and 2000 h and the awakening cortisol response was assessed to evaluate the hypothalamus-pituitary-adrenal axis activity. The results show that women with endometriosis and chronic pelvic pain of moderate intensity (4.1+/-0.58, mean+/-SEM) have higher levels of perceived stress (0.55+/-0.01 versus 0.42+/-0.01, p<0.05), a poorer quality of life expressed as lower scores for all items of the inventory and hypocortisolism. Lower levels of salivary cortisol were observed in all three samples collected, as well as in the awakening cortisol response, for women with endometriosis (0.19+/-0.09 microg/dl) when compared with controls (0.78+/-0.08 microg/dl, p<0.05 l), and it was independent of pain intensity and Mental health (MH) scores in SF-36. We concluded that women with endometriosis and chronic pelvic pain show low concentrations of salivary cortisol and a high level of perceived stress, associated with a poor quality of life. Whether the hypocortisolism was an adaptive response to the aversive symptoms of the disorder or a feature related to the etiology of endometriosis remains to be elucidated.

Monolithic supports for the characterization of commercial maize products based on their chromatographic profile. Application of experimental design and classification techniques

Modern analytical techniques based on the use of RP-HPLC with monolithic stationary phases and the application of experimental design and classification tools have been applied to the analysis of maize proteins. Solubilization conditions of maize proteins and separation conditions (temperature, detection wavelength, type and concentration of ion-pairing agent, and gradient) were optimized. The elution gradient was optimized by the application of experimental design techniques. The optimized method consisted of a linear binary gradient of water/acetonitrile/0.1% trifluoroacetic acid in three steps at a flow rate of 3 mL/min with a column temperature of 35 degrees C and UV detection at 280 nm. The developed method enabled the separation of maize proteins in an analysis time close to 8 min. Moreover, this is the first time that commercial maize products have been characterized by the use of multivariate classification techniques.

Development of a perfusion reversed-phase high performance liquid chromatography method for the characterisation of maize products using multivariate analysis

A perfusion reversed-phase high performance liquid chromatography (RP-HPLC) method has been designed to allow rapid (3.4 min) separations of maize proteins with high resolution. Several factors, such as extraction conditions, temperature, detection wavelength and type and concentration of ion-pairing agent were optimised. A fine optimisation of the gradient elution was also performed by applying experimental design. Commercial maize products for human consumption (flours, precocked flours, fried snacks and extruded snacks) were characterised for the first time by perfusion RP-HPLC and their chromatographic profiles allowed a differentiation among products relating the different technological process used for their preparation. Furthermore, applying discriminant analysis makes it possible to group the samples according with the technological process suffered by maize products, obtaining a good prediction in 92% of the samples.

Detection of reticuloendotheliosis virus in live virus vaccines of poultry

In vitro and in vivo assays have been used for the detection of reticuloendotheliosis virus (REV) in live virus vaccines of poultry. The presence of REV is confirmed by the demonstration of viral antigen or provirus in chicken embryo fibroblasts (CEFs) or in specific-pathogen-free chickens inoculated with vaccine. Using REV polyclonal or monoclonal antibodies, CEFs inoculated with vaccines can be examined for REV by immunofluorescence or immunoperoxidase staining methods. Cell lysates from such inoculated CEFs can also be used for detection of REV major group-specific antigen (p30) by an enzyme-linked immunoassay. Detection of proviral DNA by polymerase chain reaction (PCR) assays that amplifies the 291 base pairs product of REV LTR has been shown to be a sensitive and specific method for detection of various strains of REV in infected CEFs and in the blood of SPF chickens inoculated with contaminated fowlpox virus (FPV) vaccines. Recently, using PCR tests that amplify REV envelope and REV 3' LTR sequences provided a more accurate assessment of the insertion of REV provirus in FPV than PCR assays that amplify the REV 5' LTR. This paper reviews the most common methods used for testing live virus vaccines of poultry for contamination with REV.

Isolation of Salmonella sp. in sludge from septage treatment plant

Waste stabilization ponds (WSP) are an often-used option to treat faecal sludges collected from on-site sanitation systems. Since agricultural use is one of the most attractive options for sludge disposal, specific guidelines on the hygienic sludge quality must be fulfilled, such as for viable helminth eggs and Salmonella sp. Although Salmonella isolation methods are well known for other types of samples, they are not suitable for faecal sludge. The reason can be attributed to the co-existence of a native bacterial sludge flora masking Salmonella development, especially if this bacteria is present at low concentrations. In order to select the best methodology for Salmonella recovery from septage sludge, different culture media were assayed at different incubation periods and temperatures. The proposed methodology for Salmonella recovery from sludge can be summarised as follows: (1) enrichment in Rappaport-Vassiliadis broth at 43 degrees C, 48 hours, and (2) isolation in XLD agar at 40 degrees C, 24 hours. Identification of suspected colonies by biochemical tests: TSI, LIA, urease and serological confirmation with Group O Antigen.

The beneficial effect of motorised ankle dorsiflexion on the healing of diabetic foot ulcers

Many people with diabetes develop foot ulcers which, in extreme cases, lead to digit amputation. A small trial of a new device that induces ankle dorsiflexion improved peripheral circulation and resulted in the complete healing of all ulcers.

Epidermal growth factor regulation of female-dependent CYP2A1 and CYP2C12 in primary rat hepatocyte culture

In the present study, we describe the effects of medium composition in primary cultures of rat hepatocytes on the expression of two major constituent female-dependent CYP isoforms, CYP2C12 and CYP2A1. When female rat hepatocytes were cultured with the serum-free medium HepatoZYME, currently used to attain long-term maintenance of hepatocyte phenotypic expression, CYP2C12 mRNA and protein levels were markedly suppressed, despite the constant presence of growth hormone, the essential regulator of liver CYP2C12. Conversely, rat hepatocytes cultured in the serum-free medium Dulbecco's modified Eagle's medium-F12K, also supplemented with growth hormone, sustained near normal expression levels of CYP2C12 mRNA and protein for the 7 days of observations. Although media composition had no significant effect on mRNA expression of CYP2A1, protein content decreased dramatically in hepatocytes cultured with HepatoZYME medium. We were able to demonstrate the plasticity of the cells by restoring/suppressing the expression of CYP2C12 and CYP2A1 mRNA by reverting the culture conditions. Addition of the mitogen epidermal growth factor present in the HepatoZYME formulation to the Dulbecco's modified Eagle's medium-F12K culture media appreciably decreased expression of both CYP2C12 and CYP2A1 in female hepatocytes, while briefly sustaining levels of the cyclin inhibitor p21. Lastly, reduced CYP protein content observed in hepatocytes cultured with epidermal growth factor was not the result of an absence or reduction in the CCAAT/enhancer-binding protein alpha, a requisite transcription factor for CYP2C12 expression.

Unique epitopes in RNA helicase II/Gu protein recognized by serum from a watermelon stomach patient

RNA helicase II/Gu (RH II/Gu) is a nucleolar antigen originally identified using an autoimmune serum from a patient with watermelon stomach. A later report showed that anti-RH II/Gu autoantibodies were also present at low frequency in connective tissue disease (CTD) patients who did not show any symptoms suggestive of a watermelon stomach lesion. In an attempt to understand the relationship between watermelon stomach, also called gastric antral vascular ectasia (GAVE), and autoimmune disorder, we identified the antigenic sites recognized by these autoantibodies. Serum Gu uniquely recognized epitopes at amino acids 646-748 of RH II/Gu and all four CTD patient sera recognized antigenic sites within amino acids 1-173. Anti-RH II/Gu serum produced by immunizing rabbit with recombinant human RH II/Gu protein bound to the same antigenic sites recognized by the CTD patient sera, but it did not recognize the serum Gu epitopes. Results are also presented showing the use of these anti-RH II/Gu antibodies in the analysis of the evolutionary conservation of RH II/Gu in human, monkey and mouse.

Muscle and motor-skill dysfunction in a K+ channel-deficient mouse are not due to altered muscle excitability or fiber type but depend on the genetic background

The voltage-gated K+ channel Kv3.1 is expressed in skeletal muscle and in GABAergic interneurons in the central nervous system. Hence, the absence of Kv3.1 K+ channels may lead to a phenotype of myogenic or neurogenic origin, or both. Kv3.1-deficient (Kv3.1-/-) 129/Sv mice display altered contractile properties of their skeletal muscles and show poor performance on a rotating rod. In contrast, Kv3.1-/- mice on the (129/Sv x C57BL/6)F1 background display normal muscle properties and perform like wild-type mice. The correlation of poor performance on the rotating rod with altered muscle properties supports the notion that the skeletal muscle dysfunction in Kv3.1-/- 129/Sv mice may be responsible for the impaired motor skills on the rotating rod. Surprisingly, we did not find major differences between wild-type and Kv3.1-/- 129/Sv skeletal muscles in either the resting or action potential, the delayed-rectifier potassium conductance (gK) or the distribution of fast and slow muscle fibers. These findings suggest that the Kv3.1 K+ channel may not play a major role in the intrinsic excitability of skeletal muscle fibers although its absence leads to slower contraction and relaxation and to smaller forces in muscles of 129/Sv Kv3.1-/- mice.

Cytochrome c oxidase, Cu,Zn-superoxide dismutase, and ceruloplasmin activities in copper-deficient bovines

The activity of several cuproenzymes in relation to the immune system was examined in serum and blood cells from bovines with molybdenum-induced copper deficiency. Five female cattle were given molybdenum (30 ppm) and sulfate (225 ppm) to induce experimental secondary copper deficiency. Ceruloplasmin activity was determined in serum. The Cu,Zn-superoxide dismutase and cytochrome c oxidase activities were measured in peripheral blood lymphocytes, neutrophils, and monocyte-derived macrophages. Copper deficiency was confirmed from decreased serum copper levels and the animals with values less than 5.6 micromol/L were considered deficient. The content of intracellular copper decreased between 40% and 70% in deficient cells compared with the controls. In copper-deficient animals, the serum ceruloplasmin activity decreased to half of the control value. Both of them, the Cu,Zn-superoxide dismutase and the cytochrome c oxidase activities, undergo a significant reduction in leukocytes, showing differences among diverse cell populations. We concluded that the copper deficiency alters the activity of several enzymes, which mediate antioxidant defenses and ATP formation. These effects may impair the cell immune functionality, affecting the bactericidal capacity and making the animals more susceptible to infection.

D3 receptor knockdown through antisense oligonucleotide administration supports its inhibitory role in locomotion

To study the specific contribution of the D3 dopamine receptor in the generation of locomotor activity, total or partially dopamine-depleted rats were pretreated with an antisense oligodeoxynucleotide for the D3 receptor (D3R-as) and locomotor activity induced by apomorphine was measured. A 35.7% increase in locomotor activity was seen in the totally dopamine-depleted rats pretreated with the D3R-as, whereas the same antisense, caused a significantly greater increase in the locomotor response (95%) in the partially dopamine-depleted rats compared with control groups (pretreated with a control oligodeoxynucleotide or vehicle). In situ autoradiography for D3 receptors showed a 27% fall in the density of D3 receptors in the islands of Calleja compared with control animals. Our results seem to confirm that D3 receptors exert an inhibitory effect on locomotor activity, through the stimulation of both pre- and postsynaptic components.

The effect of copper deficiency on the peripheral blood cells of cattle

Six female cattle were given molybdenum (30 ppm) and sulphate (225 ppm) to induce experimental secondary copper deficiency. The total and differential leukocyte numbers and lymphocyte subpopulations were counted and the neutrophil activity was assessed by means of nitroblue tetrazolium reduction and phagocytosis of sheep erythrocytes. The serum caeruloplasmin activity and concentration were also determined. Copper deficiency was confirmed from decreased serum copper levels, the animals with values less than 5.9 mumol/L being considered deficient. Total leukocyte numbers were not affected by the copper deficiency. However, differential counts showed a marked increase in monocyte subpopulations, a significant decrease in B lymphocytes and reduced neutrophil activity. The serum caeruloplasmin activity was decreased about 50%, but the total serum protein concentration was less altered. We concluded that the effect of these changes on the animals' immune competence may contribute to a greater incidence of infectious diseases in copper-deficient cattle.

Effect of docosahexaenoic acid on the synthesis of phosphatidylserine in rat brain in microsomes and C6 glioma cells

Docosahexaenoic acid (22:6n-3) is the major polyunsaturated fatty acid (PUFA) in the CNS and accumulates particularly in phosphatidylserine (PS). We have investigated the effect of the 22:6n-3 compositional status on the synthesis of PS. The fatty acid composition of brain microsomes from offspring of rats artificially reared on an n-3-deficient diet showed a dramatic reduction of 22:6n-3 content (1.7 +/- 0.1%) when compared with control animals (15.0 +/- 0.2%). The decrease was accompanied by an increase in docosapentaenoic acid (22:5n-6) content, which replaced the 22:6n-3 phospholipids with 22:5n-6 molecular species, as demonstrated using HPLC/electrospray mass spectrometry. The n-3 deficiency did not affect the total amount of polyunsaturated phospholipids in brain microsomes; however, it was associated with a decrease in the total polyunsaturated PS content and with increased levels of 1-stearoyl-2-docosapentanoyl (18:0/22:5n-6) species, particularly in phosphatidylcholine. Incorporation of [3H]serine into PS in rat brain microsomes from n-3-deficient animals was slightly but significantly less than that of the control animals. Similarly, C6 glioma cells cultured for 24 h in 22:6n-3-supplemented media (10-40 microM) showed a significant increase in the synthesis of [3H]PS when compared with unsupplemented cells. Our data show that neuronal and glial PS synthesis is sensitive to changes in the docosahexaenoate levels of phospholipids and suggest that 22:6n-3 may be a modulator of PS synthesis.

Effects of chronic ethanol on the mobilization of arachidonate and docosahexaenoate stimulated by the type 2A serotonin receptor agonist (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride in C6 glioma cells

We studied the effects of chronic ethanol exposure on the mobilization of polyunsaturated fatty acids stimulated by activation of the type 2A serotonin receptor in C6 glioma cells. In our in vitro model, we prelabeled cells with [3H]arachidonate and [14C]docosahexaenonate and subsequently stimulated with the type 2A serotonin receptor agonist (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride. In as early as 10 days of exposure to 20 or 50 mM ethanol, the (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride-simulated mobilization of [3H]arachidonic acid [[3H]AA) and [14C]docosahexaenoic acid ([14C]DHA) was significantly inhibited, and this inhibition was accompanied by decreased mobilization of intracellular [Ca2+]i. Exposure to ethanol did not alter significantly the release of [3H]AA and [14C]DHA stimulated by the calcium ionophore A23187 nor the incorporation of [3H]AA and [14C]DHA into cellular lipids. Decreased mobilization of polyunsaturated fatty acids and calcium in astroglia may contribute to neurotoxicity caused by chronic ethanol exposure.

Mobilization of arachidonate and docosahexaenoate by stimulation of the 5-HT2A receptor in rat C6 glioma cells

In this study, we demonstrate that astroglial 5-HT2A receptors are linked to the mobilization of polyunsaturated fatty acids (PUFA). Stimulation of C6 glioma cells, prelabeled with [3H]arachidonate (AA, 20:4n6) and [14C]docosahexaenoate (DHA, 22:6n3), with serotonin and the 5-HT(2A/2C) receptor agonist (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) resulted in the mobilization of both [3H] and [14C] into the supernatant of the cell monolayers. The increased radioactivity in the supernatant was mainly associated with free fatty acids. Experiments using inhibitors of phosphoinositide-specific phospholipase C and PLA2, inhibited the DOI-stimulated mobilization of AA and DHA, suggesting the involvement of both phospholipases. Ketanserin (1 microM), a 5-HT(2A/2C) receptor antagonist, and MDL 100,907 (R(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-pi peridine-methanol) (1 microM), a highly selective antagonist for 5-HT2A receptors, significantly decreased the DOI-stimulated release of AA and DHA. These results indicate that the 5-HT2A receptor is coupled to the mobilization of PUFA. The release of AA and DHA in response to serotonin may represent a mechanism through which astroglia provide these polyunsaturated fatty acids to neurons.

A 7Li and 19F NMR relaxation study of LiCF3SO3 in plasticised solid polyether electrolytes

7Li and 19F NMR relaxation time (T1, T2, T1 rho) measurements have been used to probe the dynamics of LiCF3SO3 dissolved in an amorphous co-polymer poly(ethylene oxide-co-propylene oxide), and in particular the influence of the plasticising agents propylene carbonate and dimethyl formamide. The changes in relaxation behaviour of 19F and 7Li with increasing plasticiser concentration are very different, as is the effect of each plasticiser. These differences can be explained qualitatively in terms of the interaction between the plasticiser and the ions. Preliminary 7Li T1 rho measurements reveal two components at low temperatures.

Extracellular heparin inhibits Ca2+ transients and contraction in mammalian cardiac myocytes

The effect of heparin on Ca2+ transients and cell shortening was studied in isolated cardiac myocytes from rat and guinea-pig ventricles. Ca2+ signals were measured with the fluorescent indicator fura-2. Heparin reversibly decreased Ca2+ transients and cell shortening in a dose-dependent manner. Half and complete blockade were obtained with 50microg/ml and 200microg/ml heparin, respectively. The dihydropyridine agonist BAY K 8644 (50nM) antagonized the effects of heparin. However, Ca2+ release elicited by caffeine (10mM) was not affected by heparin. The actions of heparin were also studied in multicellular preparations. In papillary muscle, heparin (5mg/ml) reversibly reduced the amplitude of the plateau of the action potential and the associated peak tension. BAY K 8644 (500nM) also antagonized these effects. It is proposed that heparin interacts with dihydropyridine-sensitive Ca2+ channels to cause a decrease of Ca2+ transients and contractility in heart.

[Reorganization of the graduate course in pediatric nursing at the nursing school at the Federal University at Minas Gerais. Evaluation of the process]

In this paper, the faculty from the Pediatric Nursing Subject (Undergraduate Course) at the Nursing School of Universidade Federal de Minas Gerais evaluate a teaching project. Its main purpose was to reorganize the Subject based on ABATT; MCMAHON's approach to the teaching-learning process. The authours evaluate the results and highlight the positive aspects occurred due to the reorganization and confirm the need to continue the process.

Transrectal fine needle aspiration biopsy of the prostate combining cytomorphologic, DNA ploidy status and cell cycle distribution studies

Fine needle aspiration (FNA) cytology of the prostate is becoming a common diagnostic procedure, and DNA flow cytometry (FCM) data have been shown to correlate with the pattern of evolution of prostatic carcinoma, thus emphasizing the importance of assessing both parameters together. The aim of the present paper is to analyze the presence of DNA aneuploidy, cell cycle distribution and their relationship with the cytologic grade in transrectal fine needle aspiration prostate biopsies from 78 consecutive patients. Herein we studied the DNA ploidy status, the cell cycle distribution and their relationship with cytologic grade in transrectal FNA biopsies of the prostate from 78 consecutive patients -47 benign hyperplasias and 31 carcinomas- as analyzed by a reproducible FCM method for single cell suspension preparations, data acquisition and analysis. The presence of DNA aneuploidy was detected in 39% of the carcinomas and it was found to be a specific marker for prostatic carcinoma since all benign hyperplasia cases were diploid. Moreover, the incidence of DNA aneuploidy increased progressively from well-differentiated to moderately-differentiated and poorly-differentiated carcinomas (p = 0.005). Regarding cell cycle distribution, carcinomas displayed a higher proportion of both S-phase (p = 0.0003) and G2/M-phase (p = 0.0006) cells with respect to benign hyperplasias. Aneuploid cases also showed a greater proliferation rate as compared to the diploid carcinomas, regardless of their cytopathologic grade (p = 0.00001). Despite the fore-mentioned results, these correlations were far from being absolute, suggesting that combined assessment of these parameters should give additional information for the clinical management of prostatic disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of immunological stimulation on the production of platelet-activating factor by rat peritoneal cells: its relevance to anaphylactic reactions

The production of platelet-activating factor (PAF) by rat peritoneal cells was studied using as stimuli either monoclonal IgE, IgG1 or IgG2b anti-DNP (2,4-dinitrophenyl), and DNP-BSA. Peritoneal cells sensitized in vitro with any of these antibodies at concentrations higher than 10 nM and challenged with 1 microM DNP-BSA produced PAF. PAF production was also elicited by preformed IgE/ and IgG2b/DNP-BSA immune complexes, preferentially at a large antigen/antibody ratio. The production of PAF was unrelated to the activation of mast cells, since it occurred in populations depleted of mast cells by adherence to plastic dishes. Moreover, the release of [3H]serotonin from IgE-sensitized mast cells showed a time-course more rapid than PAF production and occurred in cells sensitized with IgE at concentrations lower than those required for PAF formation. In contrast, peritoneal cells sensitized with IgG1 and IgG2b failed to release [3H]serotonin. Rat peritoneal cells showed a significant ability to catabolize PAF by intracellular PAF-acetylhydrolase in view of both the amounts of enzyme activity assayed in cellular homogenates, and the 15-fold increase on controls of PAF quantities detected in peritoneal cells treated with phenylmethylsulfonyl fluoride (PMSF), a known inhibitor of PAF-acetylhydrolase. The PAF activity produced upon PMSF addition showed a retention time on reverse-phase HPLC which suggests structural identity to PAF produced by either immunological challenge or ionophore A23187. These data suggest that PAF formed during rat passive anaphylaxis reactions depends on the activation of mononuclear phagocytes. This production may be triggered by two types of low affinity receptors: Fc epsilon RII/CD23 and Fc gamma R. The ability of peritoneal cells to catabolize PAF by intracellular acetylhydrolase seems unaffected by immunological stimulation.

Patterns of alcohol consumption among the general population of Castile and Leon (Spain)

A total of 2500 individuals, aged 14-70, who live in Castile and Leon (Spain), were surveyed in the spring of 1989 with regard to their alcohol consumption and its patterns. Among those surveyed 26.2% were 'daily' drinkers and 66.0% 'weekly' drinkers. Differences of alcohol use (frequency) and intake were reviewed with regard to sociodemographic factors such as gender, age, and marital status. Beer (52.6%) was the favourite drink, with wine (20.6%) the second most commonly consumed alcohol beverage. Most of those surveyed (54.6%) were 'light' drinkers (1-39 g/day of pure alcohol), while 3.0% had an intake of over 80 g/day ('heavy' drinkers). The average age at which they started drinking was 16.2 years. The results allow a better understanding of the pattern of alcohol consumption in Spain.

Assessment of iron status by erythrocyte ferritin in uremic patients with or without recombinant human erythropoietin therapy

Erythrocyte ferritin may be a better estimator of iron bioavailability than the conventional markers of iron stores (serum ferritin and transferrin saturation). To investigate the accuracy of these conventional markers in uremic patients compared with erythrocyte ferritin, we studied 29 chronic hemodialysis patients on erythropoietin (EPO) therapy, 18 without EPO therapy, and 22 healthy control subjects. Apart from the red blood cell indices, serum ferritin, transferrin saturation, and erythrocyte ferritin, the analytical study included red blood cell protoporphyrin and plasma aluminum levels. The control group showed erythrocyte ferritin concentrations between 8.3 and 12.5 attograms/cell (95% confidence interval). In the EPO group, red blood cell protoporphyrin correlated negatively with erythrocyte ferritin, but not with serum ferritin or transferrin saturation. In the non-EPO group, serum ferritin, erythrocyte ferritin, and transferrin saturation did not correlate with red blood cell protoporphyrin. Even though erythrocyte ferritin correlated well with serum ferritin in the EPO group (r = 0.61, P = 0.0003), the sensitivity of normal serum ferritin levels (30 to 300 ng/mL) to discard a low erythrocyte ferritin concentration (erythrocyte ferritin less than 7 ag/cell) was 0.53, while the sensitivity of serum ferritin at levels less than 30 ng/mL to indicate an absolute iron deficiency expressed as a low erythrocyte ferritin concentration was 0.28. Only values of serum ferritin and transferrin saturation greater than 300 ng/mL and 35%, respectively, could rule out a relative iron deficiency expressed as a low erythrocyte ferritin and high red blood cell protoporphyrin concentration. Plasma aluminum levels did not correlate with red blood cell protoporphyrin or erythrocyte ferritin levels in either uremic group.(ABSTRACT TRUNCATED AT 250 WORDS)

Sulfhydryl alkylating agents induce calcium current in skeletal muscle fibers of a crustacean (Atya lanipes)

Voltage-clamp experiments using the three-microelectrode voltage clamp technique were performed on ventroabdominal flexor muscles of the crustacean Atya lanipes. Potassium and chloride currents were found to underlie the normal, passive response of the muscle. Blocking potassium currents with tetraethylammonium and replacing chloride ions with methanesulfonate did not unmask an inward current. By treating the muscle with the sulfhydryl-alkylating agent 4-cyclopentene-1,3-dione an inward current was detected. The current induced by the agent is carried by Ca2+, since it is abolished in Ca(2+)-free solutions. The induced Ca2+ current is detected at about -40 mV and reaches a mean maximum value of -78 microA/cm2 at ca. -10 mV. At this potential the time to peak is close to 15 msec. The induced Ca2+ current inactivated with 1-sec prepulses which did not elicit detectable Ca2+ current; the fitted hx curve had a midpoint of -38 mV and a steepness of 5.0 mV. Measurements of isometric tension were performed in small bundles of fibers, and the effects of the sulfhydryl-alkylating agents 4-cyclopentene-1,3-dione and N-ethylmaleimide were investigated. Tetanic tension was enhanced in a strictly Ca(2+)-dependent manner by 4-cyclopentene-1,3-dione. The amplitude of K+ contractures increased after treatment with N-ethylmaleimide. It is concluded that Ca2+ channels are made functional by the sulfhydryl-specific reagents and that the increase in tension is probably mediated by an increase in Ca2+ influx through the chemically induced Ca2+ channels.

Patterns of drug use in Castille and Leon (Spain)

A total of 2500 individuals, aged 14-70 years and living in Castille and Leon (Spain), were surveyed in the spring of 1989 with regard to their drug consumption and patterns of use. 'Lifetime' drug users' rates were 30.0% for cannabis, 5.4% for cocaine, 5.2% for amphetamines, 2.4% for psychedelic drugs, 1.5% for opiates, 1.1% for tranquillizers, and 0.4% for inhalants. 'Regular' drug users were more common among cannabis--2.8% of the surveyed--and less frequent among cocaine, opiates and amphetamine users--0.3% of everyone of the substances mentioned above. 'Lifetime' drug users were more common among males than among females, among singles than among married, in those younger (18-29 years of age) and with work problems. The starting age of drug consumption ranged between the average of 15.6 years of age for those who consumed inhalants and 19.5 for those who consumed cocaine. The results allow a better understanding of the pattern of drug use in Castille and Leon (Spain), as well as the 'high' prevalence of drug use in our region.

Effect of sodium deprivation on contraction and charge movement in frog skeletal muscle fibres

Measurements of isometric tension were performed in single twitch skeletal muscle fibres and the effect of extracellular Na+ removal on contraction was investigated. Na+ withdrawal brought about an increase in the amplitude of K+ contractures and their time course became faster. The potentiation of K+ contractures depended strongly on extracellular Ca2+ and developed slowly following an exponential time course with a time constant of approximately 8 min. Removal of extracellular Na+ greatly increased the amplitude of caffeine contractures and lowered its threshold: caffeine (0.5 mM) had no effect on resting tension in Ringer's but produced contractures in Na(+)-free solutions. Intramembrane charge movement (charge 1) was monitored in contracting voltage-clamped segments of frog skeletal muscle fibres using the triple-Vaseline-gap technique. Movement of charge 1 did not depend on the presence of extracellular Na+. However, the mechanical threshold decreased by approximately 10 mV at several pulse durations and the charge which produced just detectable contractions decreased by approximately 5 nC microF-1 in the absence of extracellular Na+. Intracellular heparin (40 mg ml-1) increased the mechanical threshold by approximately 20 mV without affecting the movement of charge 1. The effect of Na(+)-free solutions on the mechanical threshold was additive to that of heparin. It is concluded that the effects of Na(+)-withdrawal on contraction take place at a location beyond the voltage sensor of excitation-contraction coupling.

Differential activation of myofibrils during fatigue in phasic skeletal muscle cells

In fatigued muscles the T-system is swollen; thus the action potential may fail to travel along the T-system or the T-tubule terminal cisternae signal may fail to bring about TC Ca2+ release. This would lead to a decrease in the number of myofibrils activated and in force development, but if fatigue is the result of a generalized process, all the myofibrils would be affected equally leading to a lower activation of all of them. We have investigated this possibility in isolated twitch muscle fibres by giving them repetitive tetanic stimulations until fatigue developed. The behaviour of myofibrils was followed with cinemicrophotography. Before fatigue, no lack of shortening of myofibrils could be found. During fatigue groups of myofibrils became wavy. When exposed to caffeine, the wavy myofibrils disappeared and tension similar to the control developed. The tension-caffeine concentration relationship was shifted to the left after development of fatigue. In low Na+ solution fatigue developed faster and after reintroducing normal Ringer, tension recovered substantially. K-contractures were smaller during fatigue. These results indicate that in this type of fatigue, a step in the EC coupling chain of events is involved in its development.

Retroconversion and delta 4 desaturation of docosatetraenoate (22:4(n-6)) and docosapentaenoate (22:5(n-3)) by human cells in culture

This study has investigated the metabolic modification of [3-14C]docosatetraenoate (22:4(n-6)) and [3-14C]docosapentaenoate (22:5(n-3)) by human cells in culture. Fetal skin fibroblasts converted as much as 20% of the incorporated [14C]22:4(n-6) to [14C]20:4(n-6) within 6 h and 41% within 48 h. Retroconversion of incorporated [14C]22:5(n-3) was less than 13% at all time points. Chain shortening of [14C]22:4(n-6) was also 2-6-fold greater than that of [14C]22:5(n-3) in retinoblastoma and vascular endothelial cells. Fibroblasts, vascular endothelial cells and retinoblastoma cells all elongated substantially more [14C]eicosapentaenoate than [14C]arachidonate to the respective C22 fatty acids. Within 3-4 days, fibroblasts incubated with either [14C]20:5(n-3) or [14C]22:5(n-3) had the same ratio of radiolabeled C22:C20 fatty acids in cellular glycerolipids. By contrast, the cells incubated with [14C]22:4(n-6) or [14C]20:4(n-6) did not reach a common C22/C20 equilibrium by 5 days. Although fibroblasts were found to desaturate [14C]22:5(n-3), a substantial lag time was observed; [14C]22:6(n-3) was 2% at 48 h and 20% at 96 h. By contrast, synthesis of [14C]22:6(n-3) by retinoblastoma cells was 51% within 6 h and greater than 90% at 96 h. Desaturation of [14C]22:4(n-6) was observed in retinoblastoma cells, but not in fibroblasts. These results thus suggest that the ratio of C22C20 polyunsaturated fatty acids in cells is regulated by the relative rates of retroconversion and chain elongation, with the net effect of the two processes favoring C20 for n-6 and C22 for the n-3 fatty acids. Furthermore, although fibroblasts desaturate [14C]22:5(n-3), the process appears to be qualitatively different from that of retinoblastoma cells.

C20 polyunsaturated fatty acids and phorbol myristate acetate enhance agonist-stimulated synthesis of 1-radyl-2-acetyl-sn-glycero-3-phosphocholine in vascular endothelial cells

This study has investigated the effect of supplementation of vascular endothelial cells with arachidonate and other polyunsaturated fatty acids on the agonist-stimulated synthesis of platelet activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine; 1-alkyl-2-acetyl-GPC). Incubation of calf pulmonary artery endothelial cells for 48 h in medium containing 40 microM arachidonate resulted in a 2-3-fold enhancement of [3H]acetate incorporation into 1-radyl-2[3H]acetyl-GPC in response to either bradykinin or calcium ionophore A23187. The effects of arachidonate supplementation were both dose- and time-dependent, requiring a minimum exogenous arachidonate concentration of 2.5 microM and an incubation time of 4-6 h. Eicosapentaenoate and docosahexaenoate also enhanced the synthesis of 1-radyl-2-[3H]acetyl-GPC, but were less potent than arachidonate; alpha-linolenate, linoleate and oleate were without effect. Although not effective as an agonist, phorbol myristate acetate potentiated A23187- and bradykinin-stimulated synthesis of 1-radyl-2-[3H]acetyl-GPC. The effects of arachidonate supplementation were synergistic with potentiation by phorbol myristate acetate. Sphingosine inhibited agonist-stimulated incorporation of [3H]acetate into 1-radyl-2-[3H]acetyl-GPC both in the presence and absence of PMA. Characterization of the radiolabeled material indicated that the primary product was the acyl analogue of PAF (1-acyl-2-acetyl-GPC) rather than PAF. The results from this study suggest that agonist-stimulated synthesis of 1-radyl-2-acetyl-GPC in vascular endothelial cells is modulated both by cellular fatty acyl composition and activation of protein kinase C. Enrichment of vascular endothelial cells with fatty acids, which are mobilized by agonist-stimulated phospholipase A2, may enhance subsequent deacylation of choline phospholipids and, thus, increase synthesis of both 1-acyl-2-acetyl-GPC and PAF.

Metabolism of platelet-activating factor in human haematopoietic cell lines. Differences between myeloid and lymphoid cells

The binding and metabolism of platelet-activating factor (PAF) was studied in human cell lines resembling myeloid cells (HL60 and U937) and B and T lymphocytes (Daudi and Jurkat). All of the cell lines were found to bind and catabolize exogenous [3H]PAF in a time- and temperature-dependent manner. PAF binding could also be demonstrated in isolated membrane fractions, which provides further evidence of the existence of true membrane receptors. Myeloid cell lines contained numbers of receptors at least 10-fold higher than in lymphoid cell lines. Biosynthesis of PAF upon challenge by ionophore A23187 could be demonstrated in HL60 and U937 cells. In contrast, lymphoid cell lines were unable to produce PAF. Incubation with [14C]acetate showed incorporation of the label into three main fractions: neutral lipids, phosphatidylcholine and PAF, but the distribution of the label varied depending on the cell line. Significant incorporation into phosphatidylcholine was observed in uninduced myeloid cell lines. A phospholipase A2 acting on 1-O-hexadecyl-2-arachidonoyl-sn-glycero-3-phosphocholine and an acetyl-CoA:lyso-PAF acetyltransferase were expressed in the HL60 cell line and showed variations in specific activity with granulocytic differentiation. In contrast, these enzyme activities were not expressed in Daudi and Jurkat cell lines. These data indicate (1) the occurrence of PAF binding and catabolism in both myeloid and lymphoid cell lines; (2) the restriction of PAF biosynthesis to myeloid cell lines, especially HL60 cells; (3) the occurrence of differentiation-elicited changes in the specific activities of the enzymes involved in PAF biosynthesis by the remodelling pathway; and (4) the central role played by the disposal of lyso-PAF, a product of the phospholipase A2 reaction, in PAF biosynthesis.

Influence of the lamp windows in end-on measurements of the refractivity in a pulsed plasma

During measurement of the refractivity of a pulsed plasma, we have detected, with the help of a Jaminlike interferometer, the optical path variation caused by lamp windows. We attribute this variation to two causes: mechanical vibration and the slow cooling that follows the sharp heating. We conclude that neither has any influence on the measurement of plasma refractivity.

Biosynthesis of platelet-activating factor (PAF) in human polymorphonuclear leucocytes. The role of lyso-PAF disposal and free arachidonic acid

Theophylline and 1-methyl-3-isobutylxanthine (MIX), compounds that block eicosanoid formation and modulate phospholipase A2 activity, inhibited in a dose-dependent manner the formation of both leukotriene B4 (LTB4) and platelet-activating factor (PAF) by human polymorphonuclear leucocytes (PMN) in response to ionophore A23187. Theophylline and MIX lacked any inhibitory effect on acetyl-CoA: lyso-PAF acetyltransferase activity, which is the rate-limiting step for PAF biosynthesis in PMN. The effect of theophylline and MIX on PAF formation could be reversed by incubating the cells in the presence of 1-10 microM exogenous lyso-PAF. Incubation of PMN homogenates in the presence of unsaturated non-esterified fatty acids resulted in dose-dependent inhibition of the acetyltransferase. This effect was linked to the presence of a free carboxyl group, since both arachidonic acid methyl ester and palmitoyl-arachidonoyl phosphatidylcholine lacked inhibitory activity. This inhibitory effect was also dependent on the number of double bonds, since arachidonic acid (C20:4) and eicosapentaenoic acid (C20:5) displayed maximal effect. Kinetic analysis showed that the effect of arachidonic acid was consistent with competitive inhibition, with a Ki value of about 19 microM. Oxidative metabolites of arachidonic acid showed a lesser inhibitory effect with the following order of potency: arachidonic acid greater than 15-HETE (15-hydroxy-6,8,11,14-eicosatetraenoic acid) greater than LTB4 greater than 5-HETE (5-hydroxy-6,8,11,14-eicosatetraenoic acid) greater than lipoxin A4. Examination of enzymes involved in CoA-dependent acylation revealed a low activity of both arachidonoyl-CoA synthetase and arachidonoyl-CoA: lyso-PAF arachidonoyltransferase. These data indicate a strong influence on PAF biosynthesis of the products of the phospholipase A2 reaction, with lyso-PAF disposal being a critical event for PAF formation, and unsaturated fatty acids acting as feed-back inhibitors. The conversion of arachidonic acid via oxidative metabolism into less active inhibitors of acetyl-CoA:lyso-PAF acetyltransferase seems to be an additional mechanism of modulation of this enzyme activity, linked to the function of lipoxygenases. Finally, the enzyme activities involved in arachidonoyl-CoA-dependent acylation of lyso-PAF show a low efficiency in capturing arachidonic acid.