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The article presents a study to assess the exposure-response correlation of lung cancer and crocidolite of Wittenoon crocidolite employees in Australia. It features results of the cohort research on the lung cancer cases of the 6910 crocidolite employees in the country until December 1994. Moreover, it features the predictors of lung cancer among patients.

Objectives: Osteophytes are common anatomical signs of advanced osteoarthritis. It remains unclear whether they develop from physio-molecular, and/or mechanical stimuli. This study examined the effects of mechanical impact on the knee joint periosteum leading to osteophyte formation., Design: Eighteen mature rats received one single impact load of 53 N (30 MPa) to the periosteum of the experimental medial femoral condyles. Contralateral knees were used as controls. Animals were sacrificed at 24 h, 3, 6 and 9 weeks post-impact. Distal femurs were harvested and prepared for histology. Hematoxylin and Eosin, and Masson's trichrome stained slides were examined by light microscopy. Nuclear density was quantified to assess the tissue reaction., Results: 24 h: The synovium membrane, fibrous and cambium periosteum were damaged. Blood infiltration pooled in the impacted medial collateral ligament (MCL) region. Week 3: A cartilaginous tissue spur, chondrophyte, was found in every rat at the impacted site of the MCL. Chondrophytes were composed of fibrocartilage and cartilage matrix, with signs of cartilage mineralization and remodelling activity. Week 6: Chondrophytes presented signs of more advanced mineralisation, recognized as osteophytes. Week 9: Osteophytes appeared to be more mineralized with almost no cartilage tissue., Conclusions: Osteophytes can be induced with a single mechanical impact applied to the periosteum in rat knees. These data indicate that a moderate trauma to the periosteal layer of the joint may play a role in osteophyte development., (Copyright © 2020 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Objective: To investigate the correlation between single nucleotide polymorphisms (SNPs) of SIRT1 gene promoter sequence and senile degenerative heart valvular disease (SDHVD). Methods: A total of 236 SDHVD patients and 285 healthy controls who visited the Affiliated Hospital of Jining Medical University between February 2012 and October 2016 were enrolled. SNPs of SIRT1 gene promoter were detected by Sanger sequencing. Typing and correlation were analyzed by χ(2) test and Logistic regression analysis. Haplotype and linkage disequilibrium were analyzed by Haploview4.2 software and SHEsis online software. The effect of SNPs on the binding of transcription factors to SIRT1 gene promoter was analyzed by electrophoretic mobility shift assay(EMSA). The transcription factors affected by SNPs were predicted by Transfac online software. Results: The frequency distribution of GG genotype of rs3740051 in the SDHVD group was significantly higher than that in the control group (χ(2)=4.855, P= 0.028). There was a correlation between GG genotype of the rs3740051 and SDHVD. After adjusting for age, the risk of SDHVD in the carrier of GG genotype was 3.079 times higher than that of AA genotype( OR= 3.079, 95 %CI : 1.156-8.201, P= 0.024). The five SNPs (rs3740051, rs932658, rs35995735, rs3740053 and rs2394443) showed strong linkage disequilibrium(D'>0.8). The haplotype analysis of the five SNPs (haplotype frequency<0 was ignored in the analysis) showed that 11 haplotypes ( P< 0.05) were formed, and the frequency of *A**C, AA**C, *AG*C, AAG*C, AA*AC, *AGAC and AAGAC in SDHVD group were significantly higher than that in control group ( P< 0.05, OR> 1, 95 %CI does not contains 1). EMSA showed that the color of the binding bands incubated by wild type probe and nucleoprotein was darker than that incubated by DNA sequence variation probe and nucleoprotein. Conclusion: The GG genotype of rs3740051 is associated with SDHVD and may be a risk genotype for SDHVD. The haplotype AC (across rs932658 and rs2394443) may be a dangerous haplotype of SDHVD. rs3740051 may affect the occurrence and development of SDHVD by interfering with the binding of FOXC protein to SIRT1 gene promoter.

The recent development of genetic mouse models presenting life-long alterations in expression of the genes for atrial natriuretic peptide (ANP) or its receptors (NPR-A, NPR-C) has uncovered a physiological role of this hormone in chronic blood pressure homeostasis. Transgenic mice overexpressing a transthyretin-ANP fusion gene are hypotensive relative to the nontransgenic littermates, whereas mice harboring functional disruptions of the ANP or NPR-A genes are hypertensive compared with their respective wild-type counterparts. The chronic hypotensive action of ANP is determined by vasodilation of the resistance vasculature, which is probably mediated by attenuation of vascular sympathetic tone at one or several prejunctional sites. Under conditions of normal dietary salt consumption, the hypotensive action of ANP is dissociated from the natriuretic activity of the hormone. However, during elevated dietary salt intake, ANP-mediated antagonism of the renin-angiotensin system is essential for maintenance of blood pressure constancy, inasmuch as the ANP gene "knockout" mice (ANP -/-) develop a salt-sensitive component of hypertension in association with failure to adequately downregulate plasma renin activity. These findings imply that genetic deficiencies in ANP or natriuretic receptor activity may be underlying causative factors in the etiology of salt-sensitive variants of hypertensive disease and other sodium-retaining disorders, such as congestive heart failure and cirrhosis.

Background: The atrial natriuretic peptide (ANP) family is a complex system consisting of at least three polypeptides and at least three types of receptor. Each peptide interacts with different types of receptor at varying degrees of affinity. To determine if natriuretic peptide levels influence natriuretic peptide receptor expression and regulation, we examined the expression of guanylyl cyclase linked GC-A, GC-B and C-receptor in the lungs of mice with a mutation that inactivates the ANP gene (Nppa)., Methods: The mRNA level of GC-A, GC-B and C-receptor in the lung were studied by ribonuclease protection assays (RPA)., Results: Results of RPA showed that although the mRNA level of GC-A and GC-B of heterozygous ANP+/- was not different from wild type ANP+/+ mice, they were significantly higher in the homozygous mutant ANP-/- mice. In addition, C-receptor mRNA level in ANP+/- and ANP-/- was significantly lower than ANP+/+ mice. The C-receptor results were confirmed by receptor binding assays and affinity cross-linking studies., Conclusions: Taken together these data suggest that permanent removal of ANP from the natriuretic peptide system results in an up-regulation of GC-A and GC-B, and a corresponding down-regulation of C-receptor in the lung of proANP gene disrupted mice. We postulated that changes in the natriuretic peptide receptor population may result in chronic hypertension and cardiac hypertrophy in the ANP-/- mice.

Objective: Atrial natriuretic peptide (ANP) lowers arterial blood pressure (ABP) chronically, in association with vasodilation of the resistance vasculature. The mechanism mediating the chronic relaxant effect of ANP is likely indirectly mediated by interactions with tonic vasoeffector mechanisms, inasmuch as the resistance vasculature is relatively insensitive to direct cGMP-mediated relaxation by ANP. On the basis of evidence that ANP has widespread sympatholytic activity, the current study investigated whether the chronic hypotensive effect of ANP is mediated by attenuation of tonic cardiovascular sympathetic tone., Methods: Total plasma catecholamine concentration and changes in basal ABP and heart rate (HR) following autonomic ganglionic blockade were measured as indices of underlying sympathetic nerve activity in hypotensive ANP-overexpressing transgenic mice (TTR-ANP), hypertensive ANP knockout mice (-/-) and the genetically-matched wild type (NT and +/+, respectively) control mice. Pressor and chronotropic responses to norepinephrine infusion were measured in ganglion-blocked mice of all genotypes, and norepinephrine receptor binding was assessed in representative tissues of -/- and +/+ mice, in order to determine whether peripheral adrenergic receptor responsiveness is altered by ANP-genotype., Results: Basal ABP was significantly lower in TTR-ANP and higher in -/- compared to their wild-type controls. Basal HR did not differ significantly between mutant and control mice. Autonomic ganglionic blockade reduced ABP and HR in all genotypes, however, the relative decrease in ABP was significantly smaller in TTR-ANP and greater in -/- mice than in their respective controls. Total plasma catecholamine was significantly higher in -/- than in +/+ mice but did not differ significantly between TTR-ANP and NT mice. Norepinephrine infusion during ganglionic blockade elicited quantitatively similar pressor and chronotropic responses in mutant and control mice. Tissue norepinephrine binding did not differ significantly between -/- and +/+ mice., Conclusions: The present study shows that differences in endogenous ANP activity in mice, resulting in chronic alterations in ABP are accompanied by directional changes in underlying cardiovascular sympathetic tone, and suggests that the chronic vasodilator effect of ANP is, at least partially, dependent on attenuation of vascular sympathetic tone, possibly at a prejunctional site(s).

A retrospective study to assess the role of chest radiography (CR) in the control of tuberculosis (TB) in Western Australia (WA) was carried out by reviewing the annual reports from 1948 to 1983 and analysing the records at the Perth Chest Clinic (PCC) for a 12-month period in 1992-93. Mass miniature radiography in WA was introduced in 1948 and was selective up to 1951, yielding 3.3 cases of active TB per 10(3) films and accounting for 18.3% of the total notifications. It became a compulsory statewide screening procedure from 1952 to 1972. During this period the average yield was 0.7 cases/10(3) films and they accounted for 19.6% of the notifications. Thereafter the examination was again selective, detecting 0.2 cases/10(3) films and accounting for 2.7% of the notifications for 1977-79. From 1 July 1992 to 30 June 1993, a total of 2456 asymptomatic persons had chest X-ray records at the PCC relating to contact tracing (456), positive Mantoux reaction (330), pre-employment clearance as child-care workers (616) and application for permanent residence (1054). Overall, their X-rays were reported as normal in 95.4%, abnormal and of clinical significance in 2.7% and abnormal but of no significance in 1.9%. Active TB was detected in 0.2%, giving a yield of 2.4 cases/10(3) films and accounting for 10% of the notifications for the 12-month period. This study shows that mass CR, when judiciously applied, can contribute significantly to TB case-finding even in low-prevalence countries where the goal is the elimination of the disease.

Recent studies suggest that carbon monoxide (CO) derived from heme oxygenase (HO)-catalyzed metabolism of heme plays a role in the regulation of cell function and communication. In blood vessels, CO may regulate vascular smooth-muscle tone through the activation of soluble guanylyl cyclase, in a manner similar to that of nitric oxide. The objective of this study was to determine the relation between HO enzymatic activity and localization of HO protein in bovine pulmonary blood vessels. HO enzymatic activity was determined by quantitating the rate of CO formation in the microsomal fraction of homogenates of bovine pulmonary artery (BPA) and vein (BPV). HO protein was localized by immunohistochemical analysis of paraformaldehyde-fixed tissue by using polyclonal antibodies to inducible HO (HO-1) and noninducible HO (HO-2). HO enzymatic activity was measured in BPA and BPV, which correlated with the presence of HO protein. In BPA, HO enzymatic activity was found in the adventitia and medial layer; HO protein was localized in the nerves and vasa vasorum of the adventitia and was found throughout the smooth-muscle cells in the medial layer. The data clearly demonstrate the presence of HO enzymatic activity for the formation of CO in blood vessels that contain HO protein.

Atrial natriuretic peptide (ANP) is a vasoactive molecule with a potential role in modulating uteroplacental blood flow. We examined the expression of ANP in the third-trimester fetomaternal interface by immunohistochemistry performed on sections of placental tissue as well as by reverse transcriptase-polymerase chain reaction (RT-PCR) and RIA performed on isolated, purified term trophoblasts. Results from immunohistochemical studies on ten normal term placental samples revealed labeling of extravillous interstitial and cytotrophoblastic shell trophoblasts. The trophoblastic identity of the cells was determined by labeling of adjacent serial sections with anti-cytokeratin antibody. Labeling of decidual tissue was also observed in some samples (3 of 10 samples), whereas villous trophoblastic tissue showed no labeling. RT-PCR analysis of RNA extracted from isolated third-trimester trophoblasts revealed the presence of a 0.45-kb and band corresponding to ANP mRNA. Sequencing of the amplified cDNA confirmed its identity. RIA on lysates of isolated trophoblasts revealed the presence of ANP at a level of 41 pg +/- 8 pg/10(7) cells (n = 4; range = 16.8-50.4 pg/10(7) cells). These results indicate that placental cytotrophoblastic tissue is a source of ANP. This molecule might play a role in the regulation of uteroplacental and/or fetoplacental blood flow.

To determine if defects in the atrial natriuretic peptide (ANP) system can cause hypertension, mice were generated with a disruption of the proANP gene. Homozygous mutants had no circulating or atrial ANP, and their blood pressures were elevated by 8 to 23 millimeters of mercury when they were fed standard (0.5 percent sodium chloride) and intermediate (2 percent sodium chloride) salt diets. On standard salt diets, heterozygotes had normal amounts of circulating ANP and normal blood pressures. However, on high (8 percent sodium chloride) salt diets they were hypertensive, with blood pressures elevated by 27 millimeters of mercury. These results demonstrate that genetically reduced production of ANP can lead to salt-sensitive hypertension.

The presence of high numbers of peroxidase-positive PML in ejaculated semen significantly reduced sperm HA, an important step leading to sperm capacitation. Sperm membranes at both the head and tail regions, as assessed by the hypo-osmotic viability parameter and the hypo-osmotic sperm swelling test, respectively, were not affected by peroxidase-containing leukocytes. Sperm motility was not affected, but sperm curvilinear and straight line velocity parameters were reduced in the presence of high concentrations of leukocytes in the ejaculate. The results suggested that the effect of leukocytes on sperm was through a reduction in sperm hyperactive motility but not through alterations in the sperm head and tail membranes.

Objective: To determine the effects of in vitro incubation with pentoxifylline on sperm motion characteristics of spermatozoa from normozoospermic, normokinetic specimens., Design: Prospective, controlled experiment., Setting: Andrology laboratory, university-based fertility center., Participants: Healthy, untreated male partners of couples attending the fertility center., Intervention: Each specimen was washed, pelleted by centrifugation, then resuspended in human tubal fluid medium (HTF). Two portions were incubated at 37 degrees C, one with pentoxifylline (final concentration = 1 mg/mL = 3.6 mM) and the other without pentoxifylline (control). After 1 hour, the pentoxifylline-treated portion was divided: one half was washed to remove pentoxifylline, then further incubated in HTF; the other half remained incubated in HTF with pentoxifylline., Main Outcome Measures: Motility, hyperactivation, amplitude of lateral head displacement (ALH), curvilinear velocity (VCL), straight line velocity (VSL), linearity (LIN), beat-cross frequency., Results: Incubation with pentoxifylline did not increase motility, VSL, LIN, or beat-cross frequency but did significantly increase HA, VCL, and ALH at 1, 2, and 4 hours, compared with control. Incubation in control medium without pentoxifylline did not significantly increase any of the parameters measured. After 24 hours of incubation with or without pentoxifylline, all parameters measured were significantly decreased, with the exception of LIN., Conclusions: Pentoxifylline does not increase percentage motility of washed spermatozoa in capacitation medium. Enhancement of sperm HA by pentoxifylline in capacitation medium occurs with normozoospermic, normokinetic semen specimens. This effect persists for up to 4 hours when pentoxifylline is removed from the medium after 1 hour of incubation.

Previous reports (2, 3) have suggested that pentoxifylline increases sperm motility. In this preliminary report based on five asthenozoospermic and five normal motility semen samples, we were unable to demonstrate any statistically significant effect of pentoxifylline on percent motility of human spermatozoa. However, in vitro exposure to capacitation medium with pentoxifylline may lead to an increase in total hyperactivated motility in asthenozoospermic samples, an effect not evident in the normal motility samples in this study.

Intracellular delivery of nonpermeant molecules to cultured cells in situ can be problematic. This work is a comparison between two methods of accomplishing this delivery; liposome-mediated delivery and electroporation. The final goal was to examine the effects of the glutathione S-transferase (GST) inhibitor Basilen Blue (BB) on glyceryl trinitrate biotransformation in porcine kidney epithelial (PK1) cells after intracellular delivery. Initial evaluation used the fluorescent markers carboxyfluorescein and lucifer yellow (LY). This was followed by biochemical analysis of glyceryl trinitrate biotransformation. Liposome-mediated delivery proved ineffective in spite of variations in the lipid composition of the liposomes and the use of an agglutinin and a fusogen. In contrast, electroporation was a very effective method for intracellular delivery of both lucifer yellow and basilen blue to the PK1 cells. The results show that in cells where Basilen Blue was introduced, there was a decrease in both the glyceryl trinitrate (GTN) biotransformation and ratio of glyceryl-1,2-dinitrate (1,2-GDN) to glyceryl-1,3-dinitrate (1,3-GDN) formed. The technique of in situ electroporation shows great promise for the assessment of a variety of nonpermeant molecules of pharmacological interest.

Objective: To study the long-term biological and metabolical effects of estradiol (E2) administered by transdermal therapeutic systems with and without the addition of medroxyprogesterone acetate (MPA)., Design: Open, randomized, comparative trial., Setting: The reproductive endocrine unit of a tertiary care university-affiliated hospital., Patients: Fifty-seven postmenopausal women were given E2 transdermally, whereas 28 were randomized to take MPA by mouth. Fifteen premenopausal women were studied for comparison., Interventions: Estradiol, 0.1 mg, was administered by a transdermal therapeutic system for 24.5 of 28 days and was cycled for 96 weeks. Medroxyprogesterone acetate, 10 mg, was given for days 13 to 25 of each 28-day cycle (E+P group), whereas the remainder received E2 only., Main Outcome Measures: Serum E2, estrone (E1), luteinizing hormone, follicle-stimulating hormone, low-density, high-density, very low-density, and total cholesterol, triglycerides, blood pressure, renin substrate, plasma renin activity, and serum aldosterone levels were measured in all subjects at baseline and in the postmenopausal women every 24 weeks until the end of study., Results: Mean +/- SE levels of E2 rose significantly from baseline at 24 weeks to 426 and 355 pmol/L for the E only and E+P groups, respectively. Smaller increases of estrone (E1) were observed to 263 and 244 pmol/L for the same respective groups. As expected, baseline levels of both gonadotropins were elevated, fell significantly with E2 administration, but remained increased in comparison with values observed in younger women. Decreases of total and low-density lipoprotein (LDL) cholesterol were observed in both groups that reached statistical significance at 48 weeks or later with the exception of LDL cholesterol in the E only group. No significant change of high-density lipoprotein or very low-density lipoprotein cholesterol or triglycerides was observed. There were reductions of mean systolic and diastolic blood pressures in both groups that reached significance at 72 weeks. Mean baseline plasma renin substrate, plasma renin activity, and serum aldosterone levels were within the ranges observed in younger, healthy women and did not change significantly with E2 administration in either group., Conclusion: These data support the long-term efficacy and safety of this form of replacement therapy, particularly in combination with MPA, in women with a uterus.

In summary, the hypoosmotic viability parameter was significantly correlated with the outcome of the thawed sperm motility. The prefreeze supravital staining for sperm viability and the hypoosmotic sperm swelling test were not predictive of the thawed sperm total motility. The hypoosmotic viability parameter was not correlated to the postwarmed sperm motility after refrigeration. The results indicated that the integrity of the sperm membranes at the head were more important than the tail membrane.

Objectives: To determine pregnancy and livebirth rates for women age 40 and older undergoing ovulation induction and to assess the impact of basal follicle-stimulating hormone (FSH) on outcome in these patients., Design: Prospective, observational., Setting: Fertility service of university medical center., Patients: Infertile couples in whom the female partner was age 40 or older referred for ovulation induction therapy., Intervention: Assessment of basal hormonal status; ovulation induction., Main Outcome Measures: Clinical pregnancy rate (PR), livebirth rate., Results: Analysis of 402 cycles in 85 women age 40 and older demonstrated a clinical PR of 3.5% per cycle (95% confidence interval [CI] 1.7% to 5.3%). The livebirth rate was 1.2% per cycle (95% CI 0.1% to 2.3%). Women with a basal FSH < 25 IU/L and age < 44 years had a clinical PR of 5.2% per cycle (95% CI 2.5% to 7.9%) compared with 0.0% per cycle (95% CI 0.0% to 2.1%) in cases in which either basal FSH was > or = 25 IU/L or age was > or = 44 (P < 0.005). The prognostic importance of basal FSH and chronological age was confirmed by multivariate logistic regression analysis. The predictive value of the resulting regression equation was high (R2 = 0.94; P < 0.01)., Conclusions: Pregnancy and livebirth rates are generally low during ovulation induction in women age 40 and older. In combination, basal FSH and chronological age are accurate predictors of PR, in these couples and can define a subset of patients with a more favorable prognosis. The spontaneous abortion rate in women who do conceive is high, substantially lowering the livebirth rate.

The relationship between the arterial blood pressure and the composition of the tunica media in spontaneously hypertensive, Wistar-America and Wistar-Kyoto rats was examined. The systolic blood pressure of the spontaneously hypertensive rat, measured through an intra-arterial cannula, was significantly higher than that of the controls from 5 weeks and became hypertensive by 18 weeks of age. However, the content of the tunica media of the abdominal aortal and renal artery of the spontaneously hypertensive rats, as revealed by EM stereological analysis, and measurements of the thickness of the wall and diameter of the lumen, were not significantly different from the controls, at least up to the age of 18 weeks. The result of the present investigation suggests that the elevation of arterial blood pressure in the spontaneously hypertensive rat during the first 18 weeks of postnatal development is not a result of stereologically detectable changes in the composition of the tunica media of the abdominal aorta and renal artery.

In a digital camera the position of a scintillation event is computed following analog-to-digital conversion of photomultiplier pulse charges. Digital position analysis is essentially a mathematical inversion procedure based upon calibrated responses of the photomultipliers to scintillations from a narrow-beamed source that maps a detector's field of view. Operationally, a camera's image characteristics are optimized by means of computer-generated inversion reference tables, individually tailored to the specific response characteristics of each detector. Design considerations indicate that cameras of varied configurations, e.g., linear, disc-shaped, rectangular, or cylindrical, can be analyzed by this method. Also, for any given electro-optical system, energy resolution, spatial characteristics, and event-rate performance can be made superior to analog systems. The measured performances of a one-dimensional test camera, although limited in its optical and electronic design, support this conclusion.

Early elevation of the serum myoglobin level in acute myocardial infarction (AMI) has been noted for years. In this study, 39 patients admitted to the Coronary Care Unit with acute chest pain within 72 hours (mean 12 +/- 15 hours) or electrocardiographic changes suspected of acute myocardial infarction had a serum myoglobin latex agglutination test to evaluate its diagnostic accuracy in acute myocardial infarction. Of these 39 patients, 24 had documented acute myocardial infarction as their final diagnosis. By the time of admission, 18 of the 24 cases with infarction had positive myoglobin tests (sensitivity 75%). Of those 15 cases without myocardial infarction, 13 had negative myoglobin tests (specificity 87%). If only those 17 cases admitted within 5 hours of the onset of chest pain were analyzed, the serum myoglobin test became positive in 8 of 10 cases with documented AMI but the 2 cases with negative results turned positive 2 hours later (sensitivity 80% to 100%). Due to the fact that myoglobin tests were negative in all other 7 cases without infarction, the specificity was 7/7 (100%). In contrast, the creatine phosphokinase isoenzyme study was positive only in 3 of these 10 patients with documented AMI in the first blood sample taken during admission. In conclusion, the serum myoglobin latex agglutination test is a quick and reliable method that helps in the early diagnosis of acute myocardial infarction.

We have demonstrated previously that atrial natriuretic factor (ANF) augments urinary, plasma and kidney cGMP levels but has no significant effect upon cAMP. Using cGMP as a marker, we searched for specific target sites involved in the action of ANF in the dog kidney, and observed no change of cGMP in the proximal tubules, a 2-fold increase over basal levels in the thick loop of Henle and a 3-fold elevation in the collecting duct. The most striking action on cGMP occurred in the glomeruli with a rise of up to 50-fold being evident at 1-2 min. after the addition of ANF. The results obtained in the absence or presence of a phosphodiesterase inhibitor support the notion that the effects of ANF were exerted at the level of guanylate cyclase stimulation rather than cGMP phosphodiesterase inhibition. The action of sodium nitroprusside (SNP), a direct stimulator of soluble guanylate cyclase, differed from that of ANF. The ability of the factor to enhance cGMP levels was correlated with the distribution of particulate guanylate cyclase. This study identifies the glomeruli and the distal part of the nephron as specific targets of ANF and implicates particulate guanylate cyclase as the enzyme targetted for the expression of its action.

Particulate guanylate cyclase from bovine adrenal cortex can be stimulated by ANF. A 2-fold stimulation of the enzyme was obtained with 100 nM ANF and a half-maximal stimulation, with a 5 nM dose. The stimulation by ANF persisted for at least 30 min. Various detergents, such as Triton X-100, Lubrol PX, cholate, CHAPS, digitonin and zwittergent, stimulated several-fold the activity of particulate guanylate cyclase. However, only Triton X-100 dispersed particulate guanylate cyclase without affecting its response to ANF. The dose-response curve of ANF stimulation of the particulate and the Triton X-100 dispersed enzyme was similar. The dispersion of a fully responsive guanylate cyclase to ANF will help us to uncover the type of interactions between guanylate cyclase and ANF. It will also be used as a first step for the purification of an ANF-sensitive particulate guanylate cyclase.