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Locating peptides generated by limited proteolysis in known protein sequences by means of computer search.

A computational method is presented for locating peptides on known protein sequences using their molecular weights (estimated by SDS polyacrylamide gel electrophoresis) and their composition (obtained by amino acid analysis from eluted gel bands). The technique is easy and rapid, and appears particularly valuable if recoveries of peptides are low, or if they are heterogeneous due to secondary proteolytic degradation. An analysis of limited proteolysis of maltoporin (Schenkman, S. et al. [1984] J. Biol. Chem. 259, 7570-7576) is used to illustrate applicability and reliability of the method, which can also be applied to confirm gene-derived sequences.

Amino Acid Sequence↗

Studying properties of neurotransmitter receptors by non-stationary noise analysis of spontaneous synaptic currents.

The properties of neurotransmitter receptor channels are important for determining synaptic transmission in the nervous system. The presence of quantal variability complicates the use of conventional non-stationary noise analysis for determining the unitary conductance and number of channels involved in synaptic currents. Peak-scaled non-stationary noise analysis has been used to compensate for quantal variability, but there is evidence that the resulting variance versus mean relationships can be transformed from parabolic to skewed. We have used computer modelling based on experimentally derived kinetic schemes to investigate such relationships and demonstrate that their shape is a consequence of the temporal structure of the fluctuations during synaptic responses. Covariance analysis showed that peak-scaling generates a skewed relationship when the covariance function decays rapidly (compared to the average response waveform), corresponding to a low correlation between fluctuations at the peak and in neighbouring regions of the decay phase. A parabolic relationship is obtained when the covariance function decays more slowly, corresponding to a higher correlation. Irrespective of a skewed or parabolic relationship, we demonstrate that the unitary current can be reliably estimated, with a coefficient of variation (CV) as low as 0.05 and bias as low as +/-2% under ideal conditions. While the shape of the variance versus mean curve after peak-scaled non-stationary noise analysis is ultimately a consequence of the kinetic properties of the channels, inadequate alignment of individual waveforms can transform the relationship from parabolic to skewed, and low-pass filtering can transform the relationship from skewed to parabolic. These findings have important implications for analysis of experimental data.

Action Potentials↗

The development of auditory evoked dipole source activity from childhood to adulthood.

OBJECTIVE: Multi-channel recordings show that observed developmental changes of late auditory evoked potentials (LAEP) depend on the location of the scalp electrode. These findings suggest that different LAEP generators have a distinct developmental course. The goal of this study was to investigate the maturational process of cortical LAEP generators. METHODS: Eighty-seven healthy children and adolescents with normal hearing, ages 5-16 years, and 21 adults, ages 20-30 years, participated in the study. Pure tone LAEP were recorded from 21 derivations. Dipole source analysis was performed by means of brain electric source analysis (BESA). Peak latencies and amplitudes of dipole source activity were estimated. RESULTS: While the number, location, and direction of dipole sources were similar in children and adults, the course of their activity differed greatly. The latencies shortened and the amplitudes decreased during development. In adolescence a new component appeared in the activity of the tangential dipole, which reflects the generators in the supra-temporal plane. The variability of parameters was greater in children than in adults. CONCLUSIONS: Since the dipole source activity of LAEP in childhood differs considerably from that in adulthood, dipole source analysis could be a useful tool for studying both normal and disturbed maturation of the auditory perceptual function.

Acoustic Stimulation↗

Future needs and expected trends in peripheral blood cell analysis: erythrocyte histograms.

Erythrocyte histograms should be analysed in accordance with the ICSH recommended protocol to determine: How many red cell populations are present and the proportion of the total red cells which are included in each population. The central tendency (mode, median & mean) and dispersion (size ratio, geometric standard deviation & coefficient of variation) for each population. The proportion of microcytic or macrocytic cells in each population. Examples are given to show how the patient's diagnosis is assisted by careful analysis of the histograms and the effect of treatment monitored by sequential testing. Histograms can be generated from blood films or from aperture-impedance and light-scatter volume measurements. Volume measurements on these systems are influenced by the red cell shape and internal refractive index. Mean cell hemoglobin concentration affects both shape in the aperture-impedance orifice and internal refractive index in light-scatter systems. There is poor agreement between volume histograms obtained on the two measuring systems and the histograms available on current automated instruments provide no more useful information than can be obtained from the blood film. Automated instruments need to produce histograms with fewer artefacts and the histograms should then be examined in accordance with the ICSH protocol. This approach should maximise the diagnostic value of the complete blood count.

Automation↗

Influence of membrane oxygenators on the pulsatile flow in extracorporeal circuits: an experimental analysis.

An experimental analysis was carried out to evaluate the effects induced by two typical extracorporeal circuits on the pressure and flow generated by a roller pump with a pulsatile module. The hydraulic behaviour of the patient was simulated by means of a mechanical mock-up system consisting of a few lumped parameters reproducing the physiologic vascular impedance. Pressure and flow tracings were acquired at different locations along the circuit using an automatic data acquisition system. Nine lest conditions with different pulse frequency and systolic time values were examined using a mean volumetric flow rate of approximately 4 l/min. A complete analysis of the results obtained in terms of pressure drops and inflow-outflow differences across the components of the arterial line, as well as the calculation of the hydraulic pulsatile power along the circuit, allowed us to assess the influence of the various components upon the pulsatility. The results indicated that the membrane oxygenators tested slightly affect the pulsatility of the flow and the pressure; on the contrary the arterial pipe line is responsible for large damping and head losses. To optimize the use of pulsatile flow for cardiopulmonary bypass it is necessary to reduce the length of the arterial pipe lines thus integrating the circuit as much as possible.

Cardiopulmonary Bypass↗

Digital analysis of the pharmacological effects of in vitro ischemia on rabbit corpus cavernosum.

PURPOSE: Regulation of corporal smooth muscle tone is essential for the initiation of penile erection. In recent years, in vitro isometric tension studies using isolated corpus cavernosal tissue have been used extensively to investigate the mechanisms regulating corporal smooth muscle tone and tension. In the present study, we utilized digital analysis of contractile data generated from investigation of contractile and relaxation responses of isolated rabbit corpus cavenosum to various forms of stimulation. Digital analysis of the contractile and relaxation data allows quantitation of both maximal and mean rates of tension change, and time elapsed to maximal response. Rates of tension changes may provide additional important information regarding cellular events that mediate corporal tone and tension changes. METHODS: Sexually mature male New Zealand White rabbits were used. Each corpus cavernosum was dissected sharply from the removed penis, then two longitudinal strips were prepared for isometric tension studies and placed in individual baths. Tension was monitored continually using an 8-channel Grass Polygraph. The Grass PolyVIEW system simultaneously converted analog signals to digital information and stored data using a 486 PC computer. Each corporal strip was prestimulated with 300 mumol/l phenylephrine to produce a maximal contraction, then field stimulation (FS), carbachol and nitroprusside were applied consecutively to determine relaxation effects. This procedure was repeated after strips were deprived of glucose and oxygen (in vitro ischemia) for 1 h. The following parameters were quantitated for all responses: maximal tension change; maximal and mean rates of tension change, and time to maximal response. RESULTS: Effects of 1-hour in vitro ischemia on rabbit corporal tissue were as follows: (1) an 85% decrease in contractile response to phenylephrine, and (2) a marked increase in rate of contractile response to phenylephrine. Phenylephrine precontracted strips exhibited: (3) no change in relaxant response to FS; (4) increased relaxant responses to carbachol and nitroprusside; (5) no change in rates of relaxation in response to FS; (6) increased rates of relaxation in response to carbachol and nitroprusside, (7) no change in elapsed time to maximal relaxation in response to FS, and (8) decreased elapsed time to maximal relaxation in response to carbachol and nitroprusside. CONCLUSION: Digital analysis of the data generated facilitates recording, reviewing and analyzing of in vitro isometric tension studies on rabbit corpus cavernosum. Digital analysis allows quantification of additional parameters that have important implications for determination of mechanisms by which specific pathological processes occur.

Animals↗

Cost utility and budget impact of third-generation aromatase inhibitors for advanced breast cancer: a literature-based model analysis of costs in the Italian National Health Service.

BACKGROUND: Third-generation aromatase inhibitors are effective alternatives to tamoxifen in patients with advanced breast cancer. However, their acquisition costs might burden fixed-budget health care systems. OBJECTIVE: This study is a decision analysis of the clinical and economic consequences of alternative first-line hormone therapies for postmenopausal women with estrogen receptor-positive metastatic breast cancer in a real-life Italian health care setting. METHODS: A Markov model was developed to describe disease evolution according to data from previously published, randomized clinical trials. The costs incurred by a local community hospital in the Italian National Health Service were considered (year-2003 values). Clinical data were taken from previously published trials. A 3% discount rate was applied to both resources and life-years gained. RESULTS: Based on model estimates, mean survival times with the third-generation aromatase inhibitors anastrozole and letrozole were 30.72 and 30.64 months, respectively, as opposed to 27.28 months with tamoxifen. Mean survival times after adjustment for quality of life were 18.84 and 18.78 months with anastrozole and letrozole, respectively, and 16.14 months with tamoxifen. Baseline analysis produced incremental cost-effectiveness ratios per quality-adjusted life-year gained of 10,795 Euro (95% CI, 7737 Euro-12,899 Euro) and 16,886 Euro (95% CI, 9117 Euro-15,465 Euro) for anastrozole and letrozole, respectively, compared with tamoxifen. The observed difference between the 2 cost-utility ratios may have been mainly due to the higher acquisition costs of letrozole compared with anastrozole. Despite similar incremental cost-effectiveness ratios, anastrozole and letrozole might increase the budget for advanced breast cancer care by 12% and 18%, respectively, based on the year-2003 Italian market prices of the 2 drugs. CONCLUSIONS: In this cost-effectiveness analysis using previously published clinical data and year-2003 cost data from a community hospital in the Italian National Health Service, anastrozole and letrozole were both cost-effective alternatives to tamoxifen for first-line therapy of postmenopausal women with advanced estrogen receptor-positive breast cancer.

Anastrozole↗

[Microsatellite analysis of genetic diversity and phylogenetic relationship of eight sheep breeds in Xinjiang].

To reveal the genetic diversity and syseighttemic relationship of main sheep breeds in north Xingjiang, the genetic polymorphisms of 10 microsatellites in 8 sheep breeds and one first filial generation (F1) in north Xinjiang were studied by means of PCR, polyacrylamide gel electrophoresis and silver staining. Number of alleles, average effective number of alleles (E) and average rates of homozygote of each breeds were counted. According to allele frequencies of ten microsatellites, polymorphism information content (PIC), mean heterozygosity (h) and genetic distances were calculated for each breeds. By using the Neighbor-joining method of Molecular Evolutionary Genetics Analysis software, a dendrogram was obtained based on genetic distances. Another dendrogram was obtained by Maximum Likelihood method in PHYLIP (3.6) software. The bootstrap values were evaluated for each crunode of the dendrogram by means of bootstrap test. The systemic relationship was analyzed as well. The results showed that 8 of 10 microsatellite loci were highly polymorphic, but BM1824 and MAF65 were low and medium polymorphic respectively, so the 8 microsatellite loci were effective markers for analysis of genetic relationship among sheep breeds. The average PIC (0.5631), h (0.5721) and E(2.9) of the whole population was all lower than those of other sheep breeds reported in the documents, which showed the gene polymorphisms and genetic diversity in these sheep breeds are relative rare. The genetic distances of native Aletai, Kazak and Bashibai sheeps in Xingjiang from foreign sheep breeds and cultivated breeds bearing foreign bloodline are relatively large. Consequently, they clustered in two groups. The phylogenetic relationship between different sheep breeds was in accordance with their resource, breeding history, differentiation and localities.

Algorithms↗

Patterns of dietary intake and serum lipids interact with proteinuria as risk factors for progression of chronic renal failure.

UNLABELLED: This prospective study assessed the interactions between patterns of nutrient intake and serum lipids with other risk factors for progression of chronic renal failure. The study cohort consisted of 52 individuals with documented chronic renal failure, 18 women and 34 men, with a mean age of 65 +/- 11 years at the time of recruitment. The dependent variable was the rate of progression of chronic renal failure, which was determined by the slope of the curve generated from five or more values of the reciprocal of serum creatinine (SCr-1) and divided by time (in months of follow-up) for each patient, and recorded in dung/month. The independent variables included dietary factors (phosphorus, protein); serum lipids (total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides); proteinuria; serum phosphorus; serum albumin; serum glucose; and blood pressure. Serum creatinine was drawn in a fasting state and determined using the picric acid technique on five or more occasions for each patient. The mean monthly rate of decline in dL/mg/month was calculated for each patient. The cohort was followed for 1.5 years. Descriptive statistics were determined for all variables. Analysis of principal components was used to generate variables representing patterns of nutrient intake and serum lipids. The outcome variable was modeled using stepwise linear regression which included principal components representing dietary and serum lipid patterns. The Student's t test and the F test were used for hypothesis testing. All tests were significant at p < 0.05. RESULTS AND CONCLUSIONS: Multicolinearity prevented the inclusion of more than one individual dietary or serum lipid variable into the multiple linear regression model of rate of decline in kidney function. Principal components representing patterns of dietary intake and serum lipids, contributed to the prediction of rate of decline in renal function together with proteinuria.

Adolescent↗

Three-dimensional finite element stress analysis of a cantilever fixed partial denture.

A three-dimensional mathematical model was generated, representing a three-unit cantilever fixed partial denture and its supporting mandibular structures. First and second premolars were used as abutments with one posterior cantilever pontic. A 5 lb vertical load was applied to the pontic. Vertical and horizontal stresses were analyzed by means of a three-dimensional finite element stress analysis technique. The results showed that a cantilever pontic creates considerable compressive stress on the abutment nearest to the pontic and produces tensile stress on the abutment farthest from the pontic.

Alveolar Process↗

Vaccination in murine schistosomiasis with adult worm-derived antigens: variables influencing protection in outbred mice.

Previous studies have shown that both permissive (mouse) and partially permissive (rabbit) hosts develop high levels of resistance against Schistosoma mansoni infection after vaccination with a multiple antigen extract (SE) obtained by incubation of living adult worms in saline, plus bacterial adjuvant. To investigate variables influencing SE-induced protection in murine schistosomiasis, a series of distinct vaccination protocols were performed focussing on the immunization dose, carrier systems, route, site and amplitude of challenge infection, and time between immunization and challenge. In addition, a new approach was adopted to evaluate SE protective activity, by means of population analysis of worm burden frequency distributions in a large scale study of vaccination in outbred Swiss mice. Distinct curves of frequency and a drastic difference in worm burden distribution of frequencies from SE-vaccinated x non-vaccinated mice were found. It was shown that SE could generate 75% mean protection in outbred mice even in the absence of adjuvant. In addition SE immunization was also able to induce full protection against lethal infection. SE-induced protection could be modulated by such parameters as dose of SE immunization/challenge interval, and route of cercariae injection. These data show that SE yields very high protective activity in outbred mice, and may provide a further insight for rational design of a vaccine in experimental schistosomiasis.

Animals↗

ELISA (Embedding-Linked Interactive Single-cell Agent): an interpretable hybrid generative Artificial Intelligence agent for expression-grounded discovery in single-cell genomics.

Translating single-cell RNA sequencing (scRNA-seq) data into mechanistic biological hypotheses remains a critical bottleneck, as agentic AI systems lack direct access to transcriptomic representations while expression foundation models remain opaque to natural language. Here, we introduce ELISA (Embedding-Linked Interactive Single-cell Agent), an interpretable framework that unifies single-cell generative pretrained transformer expression embeddings with biomedical bidirectional encoder representations from transformers-based semantic retrieval and large-language model (LLM)-mediated interpretation for interactive single-cell discovery. An automatic query classifier routes inputs to gene marker scoring, semantic matching, or reciprocal rank fusion pipelines depending on whether the query is a gene signature, natural language concept, or mixture of both. Integrated analytical modules perform pathway activity scoring across 60+ gene sets, ligand-receptor interaction prediction using 280+ curated pairs, condition-aware comparative analysis, and cell-type proportion estimation, all operating directly on embedded data without access to the original count matrix. Benchmarked across six diverse scRNA-seq datasets spanning inflammatory lung disease, pediatric and adult cancers, organoid models, healthy tissue, and neurodevelopment, ELISA significantly outperforms CellWhisperer, a classical lexical retriever (BM25), and a random baseline in cell type retrieval (combined permutation test, $p < 2\times 10^{-5}$ for each), with particularly large gains on gene-signature queries (Cohen's $d = 5.98$ for mean reciprocal rank). ELISA replicates published biological findings (mean composite score 0.88), and generates candidate hypotheses through grounded LLM reasoning, bridging the gap between transcriptomic data exploration and biological discovery.

Generative Artificial Intelligence↗

Computerized analysis of the image quality of the human eye with optical aids.

Spot diagrams are computer generated by skew ray tracing for a model of the human eye which is corrected by means of a contact lens and spectacle lens. An examination of the images of a point source of light at 0 degrees and 20 degrees off the optical axis of the eye-lens system are shown. For the correction of aphakia, the performance of the contact lens is shown to be superior in off-axis optical performance.

Cataract Extraction↗

Temperature-programmed capillary electrophoresis for the analysis of high-melting point mutants in thalassemias.

The behavior of different sieving polymers for unambiguous determination of point mutations in genomic DNA, based on electrophoresis in thin capillaries, is evaluated. High melters from thalassemia patients are separated by exploiting the principle of denaturing gradient gel electrophoresis, in fact, of its variant utilizing temperature gradients (TGGE), along the migration path, encompassing the melting points of both homo- and heteroduplex, polymerase chain reaction (PCR)-amplified DNA fragments. Unlike TGGE, where the temperature gradient exists along the separation space, the denaturing temperature gradient in the fused-silica capillaries is time-programmed, so as to reach the Tm's of all species under analysis prior to electrophoretic transport past the detector window. The DNA fragments are injected in a capillary maintained (by combined chemical and thermal means) just below the expected Tm values. The deltaT applied is rather minute (1-1.5 degrees C) and the temperature gradient quite shallow (e.g., 0.05 degrees C/min). The denaturing thermal gradient is generated internally, via Joule heat produced by voltage ramps. This method is applied to the analysis of the most common point mutations in thalassemias, characterized by being high melters (in the temperature range of 60-62 degrees C) in presence of 6 M urea. Point mutants are fully resolved into a spectrum of four bands only when poly(N-acryloylaminopropanol) and hydroxyethylcellulose are used. However, the former offers the best separation capability at such high temperatures.

DNA↗

Effects of exogenous nitric oxide on neutrophil oxidative function and viability.

Previous studies have suggested that nitric oxide (NO) can modulate neutrophil function. Exposure to inhaled NO for pulmonary vasodilation could thus potentially affect neutrophil involvement in lung inflammation and infection. We evaluated the effect of exogenous NO gas exposure at clinically relevant concentrations in vitro on the oxidative function of human neutrophils. Isolated neutrophils were exposed for 2 h to either room air (RA), 80% oxygen (O2), or NO at 20 or 5 ppm blended with room air (NO20/RA, NO5/RA) or blended with 80% oxygen (NO20/O2) (NO5/O2). Neutrophils were then evaluated for superoxide anion generation with the cytochrome c reduction assay, for oxygen consumption with the Clark oxygen electrode technique, and for myeloperoxidase (MPO) release by enzyme-linked immunosorbent assay (ELISA). Neutrophil viability was determined by both trypan blue dye exclusion and fluorescence viability/cytotoxicity assay. Neutrophils exposed to NO at 20 ppm demonstrated a significant decrease in superoxide anion generation in both NO20/RA (97 +/- 46 nmol/10(6) neutrophils) and NO20/O2 (102 +/- 54 nmol/10(6) neutrophils) groups as compared with RA (190 +/- 41 nmol/10(6) neutrophils) (mean +/- SEM, P < 0.005 by analysis of variance [ANOVA] and the Student-Newman-Keuls test). No significant difference was seen at 5 ppm NO exposure. Neutrophil oxygen consumption was decreased with NO20/O2 (6.5 +/- 1.2 nmol O2/ml/min/10(7) neutrophils) as compared with RA (13.7 +/- 3.9 nmol O2/ml/min/10(6) neutrophils) or O2 alone (11.6 +/- 3.1 nmol O2/ml/min/10(7) neutrophils) (P < 0.002). MPO levels were significantly decreased with NO20/O2 (2.3 +/- 0.4 microg/ml) as compared with RA (4.0 +/- 0.4 microg/ml, P < 0.005), and also with NO5/O2. Cell viability as reflected by trypan blue dye exclusion was decreased with O2 (70 +/- 2.3%), NO20/RA (61 +/- 4%), and NO20/O2 (58 +/- 2.5%) exposure as compared with RA control (84.4 +/- 0.9%) (P < 0.0001). Decreased neutrophil viability was confirmed by live/dead assay for O2 (80.8 +/- 2.8%), NO20/RA (62.8 +/- 6.1%), and NO20/O2 (31.7 +/- 5.6%) groups as compared with RA control (95.8 +/- 1.4%, P < 0.0001). Adjusting neutrophil superoxide anion generation, oxygen consumption, and MPO values for cell viability abolished differences between exposure groups. We conclude that exogenous NO exposure at clinically relevant concentrations decreases neutrophil oxidative function, primarily as a result of reduced cell viability. Further studies are necessary to determine if these effects serve an in vivo immunoregulatory or immunosuppressive role in neutrophil response to lung injury and infection.

Adult↗

Compliance with medication in the Helsinki Heart Study.

Compliance with medication has a decisive influence on the findings in clinical intervention studies, so the reliable estimation of compliance is vital to the success of such research. This report describes the main findings about compliance in the Helsinki Heart Study, a five-year, double-blind, primary prevention trial of gemfibrozil as a lipid-lowering agent compared with placebo, in 4,081 dyslipidaemic middle-aged men. Three estimation methods were employed: capsule counting at every three-month follow-up visit, urine gemfibrozil analysis at six-month intervals, and, a novel technique, a digoxin marker added to both gemfibrozil and placebo capsules at the end of the third and fifth study years. The estimates of compliance for the study population as a whole generated by these three methods are discussed here. The mean daily capsule count showed that 36% of patients on gemfibrozil men and 39% of those on placebo took more than 90% of their capsules, while only 5% of both groups consumed half or less of the prescribed treatment. According to urinary gemfibrozil analysis, 30% of gemfibrozil subjects had more than 90% positive results and 28% had half or fewer positive. Among study completers, there were 42% gemfibrozil subjects and 50% placebo subjects who on both occasions had the good result in the digoxin marker analysis, while 14% of the gemfibrozil men and 12% of the placebo men scored 'poor' in both marker analyses. Capsule counting revealed a slight deterioration in compliance over the trial period, which was confirmed by the other two methods; for example, the proportion of positive results in the semiannual urine gemfibrozil analyses decreased from 76% to 65%. Medication compliance was slightly better in the placebo group according to capsule counting and digoxin marker methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Capsules↗

Inferring species phylogenies from multiple genes: concatenated sequence tree versus consensus gene tree.

Phylogenetic trees from multiple genes can be obtained in two fundamentally different ways. In one, gene sequences are concatenated into a super-gene alignment, which is then analyzed to generate the species tree. In the other, phylogenies are inferred separately from each gene, and a consensus of these gene phylogenies is used to represent the species tree. Here, we have compared these two approaches by means of computer simulation, using 448 parameter sets, including evolutionary rate, sequence length, base composition, and transition/transversion rate bias. In these simulations, we emphasized a worst-case scenario analysis in which 100 replicate datasets for each evolutionary parameter set (gene) were generated, and the replicate dataset that produced a tree topology showing the largest number of phylogenetic errors was selected to represent that parameter set. Both randomly selected and worst-case replicates were utilized to compare the consensus and concatenation approaches primarily using the neighbor-joining (NJ) method. We find that the concatenation approach yields more accurate trees, even when the sequences concatenated have evolved with very different substitution patterns and no attempts are made to accommodate these differences while inferring phylogenies. These results appear to hold true for parsimony and likelihood methods as well. The concatenation approach shows >95% accuracy with only 10 genes. However, this gain in accuracy is sometimes accompanied by reinforcement of certain systematic biases, resulting in spuriously high bootstrap support for incorrect partitions, whether we employ site, gene, or a combined bootstrap resampling approach. Therefore, it will be prudent to report the number of individual genes supporting an inferred clade in the concatenated sequence tree, in addition to the bootstrap support.

Animals↗

Decidual renin secretion is modulated by endothelial cells.

Because decidual renin may regulate uterine blood flow and decidual-endothelial cell proximity exists, we examined the modulation of decidual renin secretion by endothelial cells. Primary human decidual cell cultures were established. The effect of endothelial cells was studied by decidual-endothelial cocultures. Human umbilical endothelial cells were plated in half of the wells containing decidual cells and were then incubated for 24 h in serum-free media. The effect of endothelial cells was also studied by examining cAMP-mediated renin secretion using 10(-5) M forskolin under standardized conditions. We also examined the role of cell-to-cell contact by coculturing endothelial cells directly on decidual cultures and on cell inserts placed in decidual culture wells. The media were assayed for renin by radioimmunoassay (RIA) for angiotensin I (AI) after AI generation under standardized conditions. Statistical differences were analyzed by two-way analysis of variance (ANOVA) with randomized complete block design. Basal renin secretion, expressed as mean +/- SEM was 10.3 +/- 1.0 ng AI/ml/h. cAMP stimulation increased this to 15.5 +/- 1.3 ng AI/ml/h, P < 0.02. Coculture with vascular endothelium increased renin secretion to 24.3 +/- 2.4 ng AI/ml/h, P < 0.001. cAMP stimulation in cocultures increased renin secretion to 38.0 +/- 4.4 ng AI/ml/h, P < 0.002. There was no effect on cell growth as examined by total protein concentrations by coculturing or by cAMP. There was no increase in renin secretion when endothelial cells were cocultured using cell well inserts. Our data suggest that decidual renin secretion is increased by the presence of endothelial cells in direct contact with decidual cells. This supports a concept that in vivo-decidual-endothelial interaction may modulate decidual renin secretion and thereby influence regulation of uterine blood flow.

Analysis of Variance↗