Markov Modelling of Immunological and Virological States in HIV-1 Infected Patients

The purpose of this study was to evaluate the evolution of HIV infected patients and to bring out some significant factors associated with this pathology. The main criteria revealing the State of illness is viral load measurement (VL). However the CD4 lymphocytes also represent an important marker as these reflect the State of the immune reservoir. Many studies have been carried out in this field and different models have been proposed with a view to a better understanding of this disease. Multi State Markov models defined in terms of CD4 counts, or in terms of viral load, have proved to be very useful tools for modelling HIV disease progression. The model we have developed in this study is based on both the CD4 lymphocytes counts and VL. Markov models are characterized by transition intensities. In this paper we explored several structures in succession. First, we used a homogeneous continuous time Markov process with four states defined by crossed values of CD4 and VL in a given patient at a given time. Then, the effect of certain covariates on the infection process was introduced into the model via the transition intensity functions, as with a Cox regression model. Since the hypothesis of homogeneity may be unrealistic in certain cases, we also considered piecewise homogeneous Markov models. Finally, the effects of covariates and time were combined in a piecewise homogeneous model with a covariate. We applied these methods to data from 1313 HIV-infected patients included in the NADIS cohort.

Factors associated with participation in a campaign of mass treatment against lymphatic filariasis, in Leogane, Haiti

In October 2000, to interrupt transmission of Wuchereria bancrofti, an intense health-education campaign followed by a mass drug administration (MDA) with diethylcarbamazine and albendazole was undertaken in Leogane, Haiti. Three months after the MDA, which was the first in the study area, a knowledge-attitude-practice (KAP) survey, with a cluster-sample design and probability sampling, was undertaken, to determine the existing knowledge of the local residents, their attitudes toward the MDA, and the possible reasons for non-compliance. Questionnaire-based interviews were used to explore the KAP of 304 subjects (one randomly chosen resident aged > 14 years from each selected household) in 33 communities. Most (93%) of the interviewees were aware of filariasis and 72% knew at least one clinical sign of the disease. Awareness of the MDA was high (91%). The most frequently mentioned sources of information were other people (56%) and radio announcements (33%). More than 80% of the respondents encouraged other people to take the drugs distributed in the MDA and 63% had been treated. The primary reasons given for failing to take the drugs were absenteeism during the distribution (17%), use of contraceptive drugs (12%) and pregnancy (11%). In a multivariate analysis, being male [odds ratio (OR) = 3.3; 95% confidence interval (CI) = 1.5-7.4], knowing that a mosquito transmits the disease (OR = 2.6; CI = 1.2-5.4), and having learned about the MDA through posters and banners (OR = 2.9; CI = 1.2-7.5) were found to be positively associated with taking the drugs. Information from such post-treatment surveys should be useful in developing better health communication for subsequent MDA.

[Acid base balance in the fetus during labor: pathophysiology and exploration methods]

Although the majority (about 90%) of cerebral palsies are related to antenatal or postnatal causes, search for acute fetal distress during labor remains one of the primary objectives of obstetrical surveillance. Acute fetal distress leads to hypoxemia which induced hypoxia and then asphyxia of most of the organs, including the noble organs such as the brain. Most of the parameters used for fetal monitoring have good sensitivity but low specificity. Furthermore, there is a weak correlation between the different parameters measured and the neonatal status which remains difficult to predict with certainty. The general "philosophy" behind fetal monitoring consists in detecting warning signs and, when warning signs are observed, to measure one or more other parameters to assess the state of hypoxia and its consequences. Fetal heart rate is a warning sign used by all teams. Irrespective of the method used to analyze fetal heart rate when anomalies are detected, metabolic acidosis induced by anoxia is an indispensable element for assessing severity. The development of fetal hypoxia is related to two essential phenomena: anaerobic glycolysis with lactate production and glycogenolysis to meet energy needs. Metabolic acidosis can be measured directly by scalp pH or lactate measurements, or indirectly by measuring its effect on heart conduction as expressed in the ST segment. The underlying physiological mechanisms and the methods used to evaluate acid base balance are described here.

Upregulation of nerve growth factor expression by human airway smooth muscle cells in inflammatory conditions

Recent studies have suggested that nerve growth factor (NGF) may play a role in inflammation and bronchial hyperresponsiveness in asthma. Neither the types of cells that produce NGF in the human airways nor the effect of inflammation on NGF expression are clear. The two-fold aim of the present study was to determine whether airway smooth muscle produces NGF in vitro, and, if so, whether the pro-inflammatory cytokine interleukin-1beta (IL-1beta) affects this expression. Human airway smooth muscle cells in culture were incubated in the presence or absence of IL-1beta. NGF production was measured by enzyme-linked immunosorbent assay. NGF messenger ribonucleic acid (mRNA) was measured using a specific real-time fluorescent polymerase chain reaction technique, and expressed in relation to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA levels. Human airway smooth muscle cells in vitro expressed NGF constitutively (21.4+/-7.8 pg x mL(-1); 14.6+/-5.4 pg NGF complementary deoxyribonucleic acid (cDNA) x pg GAPDH cDNA(-1) (mean+/-SEM)). Stimulation with IL-1beta (0.1-30 U x mL(-1)) for 24 h induced a dose-dependent increase in NGF production (22.1 pg x mL(-1) at 10 U x mL(-1); p<0.05). The IL-1beta (10 U x mL(-1))-induced increase in NGF expression was time-dependent. It was highest for NGF protein at 10 h (1.6-fold increase over control; p<0.001) and for NGF mRNA at 2.5 h (2.4-fold increase over control; p<0.05). In conclusion, the present study clearly shows that the human airway smooth muscle cell is a source of nerve growth factor, the expression of which is upregulated in inflammatory conditions, mimicked in vitro by the addition of interleukin-1beta.

[Breast cancer and pregnancy: review of the literature]

The association of breast cancer with pregnancy is rare. It is defined as the occurrence of breast cancer during pregnancy or during the year following delivery. Patient management must be ensured by a multidisciplinary team including gynecologists, obstetricians and clinical oncologists.

[Comparison of predictive values of inhibins A and B, and plasma estradiol in IVF patients treated with GnRH agonists and recombinant FSH]

The objectives of this study were to determine the mean plasma inhibin A and B kinetics in normoovulatory patients treated by GnRH agonist and rec-FSH and to compare their predictive value with that of plasma estradiol on retrieved oocytes number and pregnancy rate. The study was carried out retrospectively in 36 normoovulatory IVF patients stimulated by GnRH agonist from D21 and rec-FSH from D2 of the following cycle. Two groups of 18 patients (having obtained or not a pregnancy) were paired for age and cause of infertility. Estradiol was measured by direct immunoassay. Inhibin A and B were measured by ELISA (Serotec Limited, Oxford, UK). Inhibin A was correlated with estradiol until P-2 (P0: day of follicles aspiration). Inhibin B rose earlier, its concentration reached its maximum at P-5. Plasma estradiol and inhibin A kinetics were not different among pregnant and nonpregnant women. There was a trend for a broader plasma Inhibin B surface under the curve in pregnant than in nonpregnant women. Estradiol and Inhibin A were correlated to the oocytes number at the end of stimulation (P-2 and D10). Inhibin B was correlated earlier than estradiol and inhibin A, at P-8 and D7. Plasma inhibin A did not demonstrate a better predictive value than estradiol neither of the oocytes number nor the chance of pregnancy. Inhibin B could be useful for early decision of cycle cancellation or stimulation adjustment.

Body composition, fasting leptin, and sex steroid administration determine GH sensitivity in peripubertal short children

Serum IGF-I levels in GH-treated subjects demonstrate a wide range of responsiveness to GH. However, the factors influencing GH sensitivity are not well known. The aim of this work was 1) to test whether body composition (determined by dual energy x-ray absorptiometry) or factors related to body composition (fasting blood glucose, FFA, C-peptide, leptin, and insulin sensitivity determined by an insulin tolerance test) influence GH sensitivity; and 2) to study the effect of sex steroid priming on GH sensitivity. We measured serum IGF-I at baseline and 24 h after a single administration of GH (2 mg/m(2)) in 60 healthy prepubertal and early pubertal children (height, -2.1 +/- 1.0 SD score). GH sensitivity, as estimated by the increase in serum IGF-I after GH administration (difference between stimulated and baseline serum IGF-I = delta IGF-I), was also determined after a short-term administration of oral ethinyl E2 in girls and im T in boys. The serum IGF-I concentration was 297 +/- 114 microg/liter at baseline and increased to 429 +/- 160 microg/liter, corresponding to a 46 +/- 29% increase over the baseline value (P < 0.0001, stimulated vs. baseline serum IGF-I). delta IGF-I was not different between gender or pubertal stage. There were positive correlations (P < 0.001) between delta IGF-I and adiposity (total body fat, r = 0.62; trunk fat, r = 0.62), fasting leptin (r = 0.64), and C-peptide (r = 0.54), and a negative correlation with fasting FFA (r = -0.33; P < 0.05) even after adjustment for age, gender, and pubertal stage. These factors remained significant independent predictors of the absolute as well as the percent increase in serum IGF-I in multiple regression analyses. Priming with T and ethinyl E2 had a similar stimulating effect on the serum GH peak in response to the insulin tolerance test. In boys, serum baseline IGF-I increased by 60%, and delta IGF-I was similar after vs. before T administration. By contrast, in girls, serum baseline IGF-I was similar, and delta IGF-I was 60% less after vs. before ethinyl E2 administration. This study indicates that 1) GH sensitivity is determined by fat mass, serum fasting leptin, C-peptide, and FFA; and 2) oral ethinyl E2 and im T have divergent effects on the IGF-I response to a single administration of GH.

Circulating microparticles from patients with myocardial infarction cause endothelial dysfunction

BACKGROUND

Shed membrane microparticles circulate in the peripheral blood of nonischemic (NI) patients and patients with myocardial infarction (MI). We investigated whether or not these microparticles would affect endothelium-dependent responses.

METHODS AND RESULTS

Rat aortic rings with endothelium were exposed for 24 hours to circulating microparticles isolated from 7 patients with NI syndromes and 19 patients with acute MI. Endothelium-dependent relaxations to acetylcholine were not affected by high concentrations of microparticles from NI patients (P=0.80). However, significant impairment was observed in preparations exposed to microparticles from patients with MI at low and high concentrations, corresponding to 0.7-fold and 2-fold circulating plasma levels (P=0.05 and 0.001, respectively). Impairment was not affected by diclofenac (P=0.47), nor by the cell-permeable superoxide dismutase mimetic Mn(III)tetra(4-benzoic acid) porphyrin chloride (P=0.33), but it was abolished by endothelium removal or by N(omega)monomethyl-L-arginine. Relaxations to the calcium ionophore ionomycin were decreased in rings exposed to microparticles from MI patients (P=0.05 and 0.009 for low and high concentrations, respectively), but microparticles from NI patients had no effect (P=0.81). Finally, high concentrations of microparticles from MI patients affected neither endothelium-independent relaxation to sodium nitroprusside (P=0.59) nor expression of the endothelial nitric oxide synthase (P=0.43).

CONCLUSIONS

Circulating microparticles from patients with MI selectively impair the endothelial nitric oxide transduction pathway and, therefore, could contribute to the general vasomotor dysfunction observed after MI, even in angiographically normal arteries.

Nerve growth factor secretion by human lung epithelial A549 cells in pro- and anti-inflammatory conditions

Nerve growth factor (NGF) has recently been presented as a possible effector of inflammation and bronchial hyperresponsiveness. However, the production of NGF in human airways as well as the regulation of its expression by inflammatory cytokines and glucocorticoids have received little attention. A549 epithelial cells were cultured in Dulbecco's modified Eagle's medium supplemented with 10% foetal bovine serum, and starved for 24 h. The effect of the pro-inflammatory cytokine interleukin-1beta (1-30 U/ml), and of the glucocorticoid dexamethasone (1 microM) on NGF secretion was studied and quantified by enzyme-linked immunosorbent assay (ELISA). In addition, NGF production within the cells was visualized by immunocytochemistry. Under basal conditions, A549 cells produced and secreted NGF (12.6+/-2.0 pg/ml). Stimulation by interleukin-1beta for 24 h induced a dose-dependent increase in NGF production (maximal at 10 U/ml with 59.6+/-3.5% increase, P<0.05). Dexamethasone (1 microM) markedly reduced the constitute NGF secretion by 44.9% (7.0+/-2.1 pg/ml, P<0.001). In addition, the interleukin-1beta-stimulated NGF secretion was inhibited to approximately the same low level (8.5+/-2.5 pg/ml, P<0.001). In conclusion, we here report that human airway A549 epithelial cells are capable of producing NGF. This production is positively regulated by the pro-inflammatory interleukin-1beta, and negatively regulated by dexamethasone.

Relationships between placental GH concentration and maternal smoking, newborn gender, and maternal leptin: possible implications for birth weight

The control of fetal growth depends on multiple hormones, including both IGF-I and placental GH (PGH) in the mother, and IGF-I rather than pituitary GH (pitGH) in the fetus. Leptin, which is produced by adipocytes and syncitiotrophoblast cells, has also been thought to influence fetal growth by an as yet unknown mechanism. This study assessed the relationships between the GH-IGF-I axis in mothers and newborns, and maternal smoking, neonate gender, and maternal and fetal leptin. We collected blood in 87 mothers at the onset of labor and cord blood immediately after birth in their 87 healthy full-term newborns. GH concentrations were log(10) transformed, and data were expressed as the geometric mean (-1, +1 tolerance factor). PGH was lower in the 30 smoking mothers, as compared with the 57 nonsmoking mothers [18.2 (11.5; 28.6) vs. 27.0 (15.1; 48.2) microg/liter, P < 0.01]. Cord blood IGF-I was lower in neonates from smoking mothers (90 +/- 44 vs. 135 +/- 65 microg/liter, mean +/- SD, P < 0.01), consistent with their lower birth weight percentile (P < 0.01). A gender effect was observed for PGH, which was higher when the newborn was female, and for newborn pitGH and newborn leptin, which were, respectively, lower and higher in females, even after adjustment for birth weight and maternal smoking category (P < 0.05 for all comparisons). Multiple regression analyses identified maternal leptin as a negative predictor of PGH (P < 0.05) and newborn leptin as a positive predictor of newborn IGF-I (P < 0.05). Maternal smoking is associated to decreased maternal PGH and cord blood IGF-I concentrations. A sexual dimorphism for PGH, newborn pitGH, and newborn leptin exists at the time of birth, but its physiological significance remains to be studied. The relationships between maternal leptin and PGH and between cord blood leptin and IGF-I are consistent with the hypothesis that leptin could contribute to the control of fetal growth.

Osteoporosis in men: a potential role for the sex hormone binding globulin

The exact mechanism of bone loss remains unknown in primary male osteoporosis. It has been suggested that estrogen and sex hormone binding globulin (SHBG) play a role in regulating bone turnover and bone mass in healthy men > 65 years of age. In the present study, 80 men (mean age 49.7 years) with bone mineral density >2.5 SD below the young adult value and 40 age-matched controls were recruited to evaluate the relationships between sex hormone levels, bone biochemical markers levels, and bone mineral density. Fasting serum samples were assayed for total and free testosterone total estradiol, and SHBG. The free androgen index, was calculated as: [total testosterone/SHBG * 100]. Bone remodeling was evaluated by measurement of urinary levels of the C-telopeptide of type I collagen (CTx) and free deoxypyridinoline (D-Pyr), serum osteocalcin, and bone-specific alkaline phosphatase (bSAP). There was no significant difference between controls and osteoporotic men according to age, body mass index (BMI), total testosterone, and estradiol. In contrast, serum SHBG level was significantly higher (+42.2%), whereas free androgen index was lower (-24.8%) in patients with primary or secondary osteoporosis. Testosterone and estradiol levels did not correlate with any bone resorption or bone formation markers. In contrast, stepwise linear regression analysis showed that SHBG was significantly correlated with D-Pyr (r = 0.45, p < 0.05) and CTx (r = 0.34, p < 0.05) in primary osteoporosis. In secondary osteoporosis, SHBG was correlated with D-Pyr (r = 0.48, p < 0.05) and bSAP (r = 0.55, p < 0.01). After adjustment for age and BMI, hip bone mineral density (BMD) was not associated with testosterone or estradiol but only with serum SHBG (r = -0.33, p < 0.01) in primary osteoporosis. The same relationship was observed in men with secondary osteoporosis (r = -0.34, p < 0.01). Among osteoporotic patients, spinal radiography showed at least one vertebral crush fracture in 36 men and none in 44. Serum SHBG concentration was significantly associated with the presence of vertebral fracture: the odds ratio was 2.0 (95% confidence interval [CI] 1.2-3.5) for an increase of one standard deviation of SHBG. In conclusion, the present study showed that serum SHBG concentration is increased in middle-aged men with primary or secondary osteoporosis and is correlated with bone remodeling markers, hip bone mineral density, and vertebral fracture risk.

Comparison of progesterone concentration determination by 12 non-isotopic immunoassays and gas chromatography/mass spectrometry in 99 human serum samples

A single serum progesterone determination may be highly predictive for early pregnancy and in vitro fertilisation and embryo-transfer outcomes. We therefore compared 12 direct non-isotopic progesterone immunoassays with gas-chromatography/mass spectrometry (GC/MS). For each assay, data from the analysis of 99 individual sera were compared with data obtained by GC/MS, using regression and bias plot analyses and the ratio method. We observed a larger difference in concentration between high and low values and a broader distribution of results for immunoassays than for GC/MS. All immunoassays displayed bias in the calibration process and a lack of specificity and/or sensitivity, to various degrees. We tried to identify the parameters of the assay procedure that might contribute to these discrepancies. None of the criteria investigated (antibodies, control and preparation of calibrators, blocking agents and choice of tracer) had a significant effect when studied alone.

Decreased flow-dependent dilation in carotid arteries of tissue kallikrein-knockout mice

- Flow-dependent dilation is a fundamental mechanism by which large arteries ensure appropriate blood supply to tissues. We investigated whether or not the vascular kallikrein-kinin system, especially tissue kallikrein (TK), contributes to flow-dependent dilation by comparing wild-type and TK-knockout mice in which the presence or absence of TK expression was verified. We examined in vitro changes in the outer diameter of perfused carotid arteries from TK(+/+) and TK(-/-) mice. In both groups, exogenous bradykinin caused a similar dilation that was abolished by the B(2) receptor antagonist HOE-140, as well as by the NO synthase inhibitor N:(omega)-nitro-L-arginine methyl ester. However, purified kininogen dilated only TK(+/+) arteries, demonstrating the essential role of TK in the vascular formation of kinins. In TK(+/+) arteries, increasing intraluminal flow caused a larger endothelium-dependent dilation than that seen in TK(-/-). In both strains the flow response was mediated by NO and by endothelium-derived hyperpolarizing factor, whereas in TK(-/-) vasoconstrictor prostanoids participated as well. HOE-140 impaired flow-dependent dilation in TK(+/+) arteries while showing no effect in TK(-/-). This compound reduced the flow response in TK(+/+) arteries to a level similar to that in TK(-/-). After NO synthase inhibition, HOE-140 no longer affected the response of TK(+/+). Impaired flow-dependent dilation was also observed in arteries from knockout mice lacking bradykinin B(2) receptors as compared with wild-type animals. This study demonstrates the active contribution of the vascular kallikrein-kinin system to one-third of the flow-dependent dilation response via activation of B(2) receptors coupled to endothelial NO release.

[Silent ischemic cardiopathy: which diabetics to examine?]

Non-Invasive coronary investigations are positive in 12 to 52% (average 22%) of type II diabetics, and 11 to 30% (average 17%) of type i diabetics. These statistics vary according to bias of recruitment. Haemodynamic lesions are found at coronary angiography in 35 to 80% of patients who have at least one positive non-invasive investigation. Nine to 12% of diabetics have silent myocardial ischaemia (SMI) confirmed by coronary angiography, compared with 1.3 to 5.3% of non-diabetic controls paired for age and sex. The higher frequency of SMI in diabetics seems to be mostly due to the increased frequency of ischaemic heart disease in diabetics. The importance of cardiac autonomic neuropathy (CAN) in SMI is controversial. The risk factors associated with SMI are those usually associated with coronary artery disease: age, masculine gender, hypercholesterolaemia, hypertriglyceridaemia, hypertension, smoking, a family history of cardiovascular disease, insulin therapy (for type II diabetes), proteinuria, retinopathy, peripheral occlusive arterial disease.... The French recommendations for investigating SMI seem to be contradictory. A single risk score in a given patient could help codify the investigation of SMI in diabetics, but this type of score has not yet been validated.

[Laparoscopic treatment of symptomatic uterine retroversion]

STUDY AIM

The aim of this retrospective study was to demonstrate the feasibility of laparoscopic Jamain-Letessier procedure and to report its results.

PATIENTS AND METHODS

Between August 1993 and September 1997, 19 patients (mean age: 29.7 years, range: 20-39 years) with painful uterine retroversion were operated on according to a laparoscopic Jamain-Letessier procedure. A preoperative pessary test was performed in 15 patients. The procedure included suture of the uterosacral ligaments to the midline and resection of the pouch of Douglas, followed by peritoneal suture.

RESULTS

The pessary test was positive in 14 of the 15 patients. Mean operating time was 2 hours. There was no conversion to laparotomy. Postoperative urinary tract infection was observed in 3 cases. Mean postoperative hospital stay was 2.5 days. With a mean 3-year follow-up, 15 patients were completely pain-free and 2 patients were partially pain-free. The 14 patients with a positive pessary test obtained a good result.

CONCLUSION

The pessary test is necessary for selection of patients. The Jalmain-Letessier procedure is easily performed laparoscopically and is associated with a low morbidity. With a mean 3-year follow-up, good results were obtained in 17 out of 19 patients (89%) and all patients with a positive pessary test obtained a good result.

Systemic adverse effect of antithyroid drugs

Antithyroid drugs adverse effects are varied and rare. Autoimmune disorders (vasculitis, lupus erythematosus, polyarthritis...) are unusual and serious complications of antithyroid drugs. Since 1945, fewer than 100 cases of systemic manifestations related to antithyroid drugs have been reported in the literature, most frequently with propylthiouracil. The outcome is usually good after drug discontinuation, but some fatal cases have been reported. Because possible cross-sensitivity with other antithyroid drugs, the appropriate treatment for hyperthyroidism relapse if a patient has had an antithyroid drug adverse reaction, should be 131I-Iodine or surgery. We report four new cases of systemic manifestations during propylthiouracil therapy.

[Cranial pachymeningitis]

INTRODUCTION

Pachymeningitis is a fibrous inflammatory process with non-specific symptoms, involving the dura mater. Due to MRI development, diagnosis is both easier and earlier.

CURRENT KNOWLEDGE AND KEY POINTS

We report seven cases and review current literature. Clinical features are headaches and cranial nerve palsies. CSF shows inflammatory changes, while MRI evidences thickening of the dura mater. Disease etiologies in the present study were tuberculosis in two cases, sarcoidosis, Lyme disease, lymphoma and dural puncture; in one case only the disease was of unknown origin. The condition of six patients improved with specific treatment.

FUTURE PROSPECTS AND PROJECTS

Further MRI development should allow detection of new forms of pachymeningitis and standardization of patients' management through the study of more important series.

[Validity of immunochemical methods for bloody progesterone: a study performed in 1998]

The aim of this study was to compare, with manufacturer's agreement, twelve direct and non-isotopic commercial assays of progesterone. We have evaluated the analytical performances: low limit detection, imprecision, accuracy (recovery and dilution tests) and we have tested some patient samples. Results were compared to a reference method using isotope dilution Gas Chromatography and Mass Spectrometry combination (GC-MS). For each assay, analytical qualities and defaults are established. Large differences are found between progesterone concentration measured on the same sample with the different methods essentially for the low concentrations. Comparison with GC-MS raised questions about the accuracy of the different assays. This work will be aid laboratories to their choice and/or validation.

Lymph node tuberculosis in the suburbs of Paris: 59 cases in adults not infected by the human immunodeficiency virus

We report 59 cases of lymph node tuberculosis in adults not infected by the human immunodeficiency virus (HIV), observed over a period of 5 years in the North Eastern suburbs of Paris. There were 31 women and 28 men; 84.7% were aged under 44 years; 69.5% were not French, and 78% had exclusive lymph node tuberculosis. A superficial distribution was found in 52 cases and a deep pattern in 17 cases. Cervical and supraclavicular lymphadenopathies were the most common (64.4%). General symptoms were present in 63% of cases. The diagnosis was established by fine needle aspiration in 10 cases and by biopsy in 36 cases. Three cases of primary resistance to anti-tuberculosis therapy were described. Lymph node tuberculosis is still present in the Paris region, independently of HIV infection, probably due to poor social conditions.

The hemoregulatory peptide N-acetyl-ser-asp-lys-pro impairs angiotensin I-induced contractions in rat aorta

The hemoregulatory peptide N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is degraded by ACE. This study was designed to examine the effect of Ac-SDKP on the contractions to angiotensin I. Experiments were performed on rat aortic rings with endothelium exposed to nitro-L-arginine. Ac-SDKP (10 and 100 microM) significantly augmented angiotensin I ED20 (from 2.0+/-0.4 to 4.2+/-1.0 and 5.0+/-0.9 nM) and ED50 (from 4.3+/-0.7 to 8.6+/-1.0 and 10.7+/-1.3 nM, respectively), but did not alter its maximal response. The contractions to angiotensin II were not affected by Ac-SDKP. No degradation of exogenous Ac-SDKP nor detectable release of endogenous Ac-SDKP were observed in the incubation medium. These results suggest that Ac-SDKP impairs angiotensin I response by inhibiting ACE and subsequent angiotensin II formation.