Negative Pressure Application via a Multi-Pressure Dial to Lower IOP in Patients with Suspected Glaucoma or Open Angle Glaucoma

PRCIS

The multi-pressure dial applies localized periocular negative pressure to safely and effectively lower IOP and represents the first non-invasive, non-pharmacologic device for IOP reduction.

OBJECTIVE

To evaluate the safety and effectiveness of the Multi-Pressure Dial (MPD) system, a device that applies periocular negative pressure to lower intraocular pressure (IOP).

SETTING

6 investigational sites, United States.

DESIGN

Prospective, assessor-masked, randomized controlled trial.

METHODS

Subjects with suspected glaucoma, ocular hypertension (OHTN), and open angle glaucoma (OAG) with baseline IOP ≥13 mmHg and ≤32 mmHg were enrolled. One eye of each subject was randomized to receive negative pressure application; the fellow eye served as a control. The study eye negative pressure setting was programmed for 60% of the baseline IOP. The primary effectiveness endpoint was the proportion of study eyes versus control eyes achieving an IOP reduction ≥20% at Day 90. Secondary endpoints included the proportion of eyes achieving an IOP reduction ≥25% at Day 90 as well as the proportion of eyes achieving an IOP reduction ≥20% at Days 30 and 60.

RESULTS

116 eyes of 58 subjects completed the study. At the Day 90 visit, 89.7% ( n =52) of study eyes versus 3.4% ( n =2) of control eyes achieved an IOP reduction ≥20% ( P <0.001). At Day 90, 77.6% ( n =45) of study eyes achieved a ≥25% IOP reduction compared to 1.7% ( n =1) of control eyes ( P <0.001). The most commonly reported adverse events were lid (17.2% study eye, 7.8% control eye) and periorbital edema (14.1% study eye, 10.9% control eye).

CONCLUSIONS

This trial demonstrates that the MPD safely and effectively lowers IOP in a group of patients that included glaucoma suspects, OHTN, and patients with OAG.

Microfluidic viscometer by acoustic streaming transducers

Measurement of fluid viscosity represents a huge need for many biomedical and materials processing applications. Sample fluids containing DNA, antibodies, protein-based drugs, and even cells have become important therapeutic options. The physical properties, including viscosity, of these biologics are critical factors in the optimization of the biomanufacturing processes and delivery of therapeutics to patients. Here we demonstrate an acoustic microstreaming platform termed as microfluidic viscometer by acoustic streaming transducers (μVAST) that induces fluid transport from second-order microstreaming to measure viscosity. Validation of our platform is achieved with different glycerol content mixtures to reflect different viscosities and shows that viscosity can be estimated based on the maximum speed of the second-order acoustic microstreaming. The μVAST platform requires only a small volume of fluid sample (∼1.2 μL), which is 16-30 times smaller than that of commercial viscometers. In addition, μVAST can be scaled up for ultra-high throughput measurements of viscosity. Here we demonstrate 16 samples within 3 seconds, which is an attractive feature for automating the process flows in drug development and materials manufacturing and production.

School Discipline and Racial Disparities in Early Adulthood

Despite interest in the contributions of school discipline to the creation of racial inequality, previous research has been unable to identify how students who receive suspensions in school differ from unsuspended classmates on key young adult outcomes. We utilize novel data to document the links between high school discipline and important young adult outcomes related to criminal justice contact, social safety net program participation, post-secondary education, and the labor market. We show that the link between school discipline and young adult outcomes tends to be stronger for Black students than for White students, and that approximately 30 percent of the Black-White disparities in young adult criminal justice outcomes, SNAP receipt, and college completion can be traced back to inequalities in exposure to school discipline.

Intraocular Pressure Measurement with Pneumatonometry and a Tonometer Tip Cover During Negative Pressure Application

Purpose

This is a 2-part study to investigate the agreement between pneumatonometry and direct pressure transducer intraocular pressure (IOP) measurements in a perfusion organ culture (POC) model where (1) the perfusion fluid column is open to atmospheric pressure, holding IOP constant to permit evaluation of the impact of negative pressure (NP) on IOP measurements, and (2) the perfusion fluid column is a closed system, allowing IOP to vary with NP application.

Methods

The first part incorporated a fluid column open to atmospheric pressure, maintaining IOP constant to permit evaluation of the effect of applied NP on IOP measurement accuracy. In the second part, the POC column was closed, allowing IOP to vary with NP application and permit evaluation of agreement between pneumatonometry and pressure transducer measurements. In each part, four perfused tissues were used in thirteen paired pre-set IOP (10, 20, 25, 30 mmHg) and NP (0, 5, 10, 15, 20 mmHg) combinations, resulting in a total of 1040 paired measurements (520 per study). The difference in IOP measurements (Δ IOP = Excursion tonometry – pressure transducer) was calculated at each paired configuration.

Results

During the first part, the mean Δ IOP was −0.7 ± 1.6 mmHg across all measurements. During the second part, the mean Δ IOP across all measurements was +0.7 ± 1.4 mmHg. At NP settings of −5, −10, −15, and −20 mmHg, across all pre-set IOPs, the mean IOP reduction via Excursion tonometry was 3.1 ± 0.3, 5.6 ± 1.3, 8.5 ± 1.7 and 11.2 ± 1.8 mmHg, respectively.

Conclusion

Measurement of IOP via Excursion tonometry yields results within the accuracy range of the pneumatonometry device (per manufacturer) and is minimally impacted by NP application. The IOP-lowering results are consistent with previous studies and further support the effectiveness of the Multi-Pressure Dial in lowering IOP relative to atmospheric pressure.

The Effect of Periocular Negative Pressure Application on Intraocular and Retrobulbar Pressure in Human Cadaver Eyes

Introduction

To investigate the effect of applying negative pressure (vacuum) to the periocular space on intraocular pressure (IOP) and retrobulbar pressure (RBP) by use of the Multi-Pressure Dial (MPD) system (Equinox Ophthalmic, Inc.).

Methods

Two eyes of two full body cadavers were studied. In each subject, the retrobulbar space, posterior segment and intra-goggle space were cannulated to provide direct IOP, RBP and intra-goggle pressure measurements via a pressure transducer data acquisition system. The goggles of the MPD system were placed over the eyes of each subject, and multiple test runs were performed, with negative pressure settings programmed to 5, 10 and 20 mmHg. IOP and RBP measurements were continuously obtained during each run and plotted against time for analysis.

Results

For both subjects, the mean reduction (± standard deviation) in IOP was 1.6 ± 0.9 (10%), 3.5 ± 1.8 (23%) and 5.6 ± 2.0 (37%) mmHg at programmed negative pressure levels of − 5, − 10 and − 20 mmHg, respectively. The overall mean change in RBP (mmHg) during negative pressure application was 0.02 ± 0.14 at − 5 mmHg, 0.03 ± 0.19 at − 10 mmHg and − 0.01 ± 0.18 at − 20 mmHg. In both subjects, the magnitude of RBP change during application of negative pressure fell below the uncertainty of the measurement system.

Conclusions

The application of negative pressure to the periocular space with the MPD decreases IOP but does not affect RBP.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-021-00442-2.

Personizing the prediction of future susceptibility to a specific disease

A traceable biomarker is a member of a disease's molecular pathway. A disease may be associated with several molecular pathways. Each different combination of these molecular pathways, to which detected traceable biomarkers belong, may serve as an indicative of the elicitation of the disease at a different time frame in the future. Based on this notion, we introduce a novel methodology for personalizing an individual's degree of future susceptibility to a specific disease. We implemented the methodology in a working system called Susceptibility Degree to a Disease Predictor (SDDP). For a specific disease d, let S be the set of molecular pathways, to which traceable biomarkers detected from most patients of d belong. For the same disease d, let S' be the set of molecular pathways, to which traceable biomarkers detected from a certain individual belong. SDDP is able to infer the subset S'' ⊆{S-S'} of undetected molecular pathways for the individual. Thus, SDDP can infer undetected molecular pathways of a disease for an individual based on few molecular pathways detected from the individual. SDDP can also help in inferring the combination of molecular pathways in the set {S'+S''}, whose traceable biomarkers collectively is an indicative of the disease. SDDP is composed of the following four components: information extractor, interrelationship between molecular pathways modeler, logic inferencer, and risk indicator. The information extractor takes advantage of the exponential increase of biomedical literature to automatically extract the common traceable biomarkers for a specific disease. The interrelationship between molecular pathways modeler models the hierarchical interrelationships between the molecular pathways of the traceable biomarkers. The logic inferencer transforms the hierarchical interrelationships between the molecular pathways into rule-based specifications. It employs the specification rules and the inference rules for predicate logic to infer as many as possible undetected molecular pathways of a disease for an individual. The risk indicator outputs a risk indicator value that reflects the individual's degree of future susceptibility to the disease. We evaluated SDDP by comparing it experimentally with other methods. Results revealed marked improvement.

Evaluation of negative pressure transfer through tissue in a benchtop cornea and eyelid model

PURPOSE

A new glaucoma treatment device, known as the multi-pressure dial (MPD), has been introduced, which offers a novel approach to IOP reduction by delivering negative pressure to the periocular region. Clinical studies have demonstrated the IOP-lowering effect of the MPD via direct measurements using pneumatonometry. It remains unclear whether the eyelids, when closed, affect the transmission of negative pressure and subsequently affect IOP reduction. This study aimed to evaluate whether the transfer of negative pressure and subsequent decrease in IOP are altered by the presence of synthetic eyelid tissue.

METHODS

A model with 13 different configurations controlling for eyelid material type, presence of slit/opening, and eyelid-cornea contact was employed. The slit modification was employed to mimic the physiologic separation that exists between the eyelids. Baseline IOP within an eye model was set at various levels ranging from 10 to 30 mmHg with applied negative pressure settings of 10, 15, and 20 mmHg utilized at each baseline IOP. The percentage of vacuum transfer was calculated by comparing baseline IOP to resultant IOP measurements following application of vacuum to the system.

RESULTS

In the open configuration (without eyelid tissue), the mean % vacuum transfer was 98.7%. The sealed, full-contact configurations exhibited values of 97.4%, 98.8%, and 97.2%. The slit configurations, which closely mimic the physiologic eyelid, demonstrated a mean % vacuum transfer of 98.7% across all settings.

CONCLUSIONS

The impact of eyelid tissue on transfer of negative pressure can be isolated and evaluated. The presence of eyelid tissue has an insignificant impact on the transfer of negative pressure, and the IOP reduction achievable with the MPD would not be altered with the eyelids closed.

Towards AR-assisted visualisation and guidance for imaging of dental decay

Untreated dental decay is the most prevalent dental problem in the world, affecting up to 2.4 billion people and leading to a significant economic and social burden. Early detection can greatly mitigate irreversible effects of dental decay, avoiding the need for expensive restorative treatment that forever disrupts the enamel protective layer of teeth. However, two key challenges exist that make early decay management difficult: unreliable detection and lack of quantitative monitoring during treatment. New optically based imaging through the enamel provides the dentist a safe means to detect, locate, and monitor the healing process. This work explores the use of an augmented reality (AR) headset to improve the workflow of early decay therapy and monitoring. The proposed workflow includes two novel AR-enabled features: (i) in situ visualisation of pre-operative optically based dental images and (ii) augmented guidance for repetitive imaging during therapy monitoring. The workflow is designed to minimise distraction, mitigate hand-eye coordination problems, and help guide monitoring of early decay during therapy in both clinical and mobile environments. The results from quantitative evaluations as well as a formative qualitative user study uncover the potentials of the proposed system and indicate that AR can serve as a promising tool in tooth decay management.

Use it or lose it? Lessons learned from the developing brains of children who are deaf and use cochlear implants to hear

In the present paper, we review what is currently known about the effects of deafness on the developing human auditory system and ask: Without use, does the immature auditory system lose the ability to normally function and mature? Any change to the structure or function of the auditory pathways resulting from a lack of activity will have important implications for future use through an auditory prosthesis such as a cochlear implant. Data to date show that deafness in children arrests and disrupts normal auditory development. Multiple changes to the auditory pathways occur during the period of deafness with the extent and type of change being dependent upon the age and stage of auditory development at onset of deafness, the cause or type of deafness, and the length of time the immature auditory pathways are left without significant input. Structural changes to the auditory nerve, brainstem, and cortex have been described in animal models of deafness as well in humans who are deaf. Functional changes in deaf auditory pathways have been evaluated by using a cochlear implant to stimulate the auditory nerve with electrical pulses. Studies of electrically evoked activity in the immature deaf auditory system have demonstrated that auditory brainstem development is arrested and that thalamo-cortical areas are vulnerable to being taken over by other competitive inputs (cross-modal plasticity). Indeed, enhanced peripheral sight and detection of visual movement in congenitally deaf cats and adults have been linked to activity in specific areas of what would normally be auditory cortex. Cochlear implants can stimulate developmental plasticity in the auditory brainstem even after many years of deafness in childhood but changes in the auditory cortex are limited, at least in part, by the degree of reorganization which occurred during the period of deafness. Consequently, we must identify hearing loss rapidly (i.e., at birth for congenital deficits) and provide cochlear implants to appropriate candidates as soon as possible. Doing so has facilitated auditory development in the thalamo-cortex and allowed children who are deaf to perceive and use spoken language.

Neural interfacing with the peripheral nervous system

Although electrical stimulation has proven to be capable of restoring neuronal function in the damaged or injured nervous system, there are several limitations to this technique. The availability of electrodes capable of selective fascicle recruitment and physiological fiber diameter recruitment (from small to large) is crucial for the development of successful prostheses. Nerve cuff electrodes have several advantages over other methods since they can provide activation of multiple muscles groups from a single site. Current cuff electrodes are reshaping the nerve into round shapes and making it difficult to recruit selectively fibers in the center of the nerve. Yet two major problems have not yet found satisfactory solutions: 1) fascicle selectivity and fiber diameter selectivity. We present here a new design that reshapes the nerve into a flat configuration, the flat interface nerve electrode (FINE). This design can improve the ability of the electrode to selectively activate the various fascicles of the nerve. Experiments to measure this selectivity were carried out on the hypoglossal nerve and its three main branches. The ability to recruit various fascicles was estimated using a selectivity index (SI). The overall performance of the FINE, as defined by the selectivity index (SI), showed a high degree of selectivity at both the fascicular and muscular levels: 0.91 +/- 0.05 (n = 5) and 0.85 +/- 0.03 (n = 4), respectively. This flat interface design minimizes the maximum distance between each contact and the fibers. Computer simulation have shown that it is possible to reverse the recruitment order by using electrode arrays placed along the nerve. This model prediction was tested in the lateral gastrocnemius/soleus branch of the sciatic nerve in cats since these muscles are innervated by fibers with different diameters. A stimulus electrode was placed around LG nerve. Tendons of LG and soleus muscles were separated and attached to two independent force transducers. The recruitment curves generated by tripolar and array electrodes were compared. Tripolar stimulation recruited LG before soleus muscles as expected, whereas the electrode array fully activated soleus while activating only 50% of LG muscles. These results show that the electrode - array is capable of reversing the recruitment order by manipulating the extracellular voltage along the nerve.

Blind source separation of nerve cuff recordings

Electrical stimulation of peripheral nerves can be used to restore partial motor function to individuals with neurological impairment. Previous work from our lab has shown that the flat interface nerve electrode (FINE) can be used to selectively stimulate fiber populations within a nerve trunk. We expect that selective recording of spatially segregated axon populations may also be possible with the FINE. The purpose of this modeling study was to assess the feasibility of using blind source separation (BSS) of the neurograms recorded with the FINE to distinguish signals from independent fascicles. We show that BSS is useful for identifying independent fascicular signals. Further, we introduce a simple post-BSS processing method that resolves the inherent permutation ambiguity of BSS, and allows the BSS-estimated signals to be deterministically related to the appropriate corresponding fascicles.

Neural prosthesis for obstructive sleep apnea

Electrical stimulation of the hypoglossal (XII) nerve has been demonstrated as an effective approach to treating obstructive sleep apnea (OSA). The physiological effects of conventional modes of stimulation (i.e., genioglossus activation or whole XII nerve stimulation), however, have yielded inconsistent and only partial alleviations of hypoapneic or apneic events. While selective stimulation of the multi-fasciculated XII nerve offers many stimulus options, it is not clear how they will functionally affect the upper airway (UAW). To study these effects, animal experiments in four beagles were performed to investigate changes in critical pressure (Pcrit), during inspiration. For simulated inspiration, only whole XII nerve stimulation (-0.9 &#177; 0.4 cmH2O) and co-activation of the GG + HG/SG muscles (-1.18 &#177; 0.6 cmH2O) produced significant (p &lt; 0.05) improvements in UAW stability (i.e., lowered Pcrit), compared to baseline (-0.52 &#177; 0.32 cmH2O). The results of this study suggest that a multi-contact nerve electrode can achieve both UAW dilation and patency, comparable to that obtained with non-selective stimulation by selectively activating the various branches of the XII nerve.

Arginases I and II: do their functions overlap?

Arginase, often perceived solely as the last of the now six enzymes of the urea cycle, exists in two forms and has a broad tissue distribution. A cytosolic form, AI, is highly expressed in the liver and is thought to be primarily involved in ureagenesis. A mitochondrial form, AII, has been thought to be more widely expressed and to be involved in the biosynthesis of polyamines, the amino acids ornithine, proline, and glutamate and in the inflammatory process, among others. This paper will address recent experiments that cast some doubt on the validity of these distinctions. Studies have now suggested that macrophages may express AI or AII in different experimental conditions, both in vivo and in vitro. In contrast, most studies, at least in cell culture, suggest that AII may be most highly expressed in cancers of a number of different types. Inhibition of arginase activity in vivo and in vitro has implicated this activity in maintaining ornithine levels for polyamine synthesis. In situ and "quantitative" PCR studies in mouse have demonstrated that AI and not AII is the predominant isoform expressed during development and in the majority of organs. Mouse knockout models for both AI and AII have been produced and are available to address their functions. Surprisingly, the AII knockout animal has no apparent phenotype except for some diminished fertility in homozygous males, consistent with the belief that AII, highly expressed in prostate, is important for sperm function in semen. The AI knockout animal has a more dramatic phenotype and dies at 10-12 days of life of hyperammonemia. The reason for the prolonged survival, as compared to other urea cycle knockout animals, may be due to the later occurrence of hypo-ornithinemia, a contention not yet proven. Transgenic manipulation of the AI knockout animal and breeding the AI and AII knockouts into single animals may address the ability of AII to rescue animals from some of the metabolic consequences of AI deficiency, as appears to happen in man. Newborn screening has given particular hope to patients affected by arginase (AI) deficiency. Increased arginine appears to be detectable by newborn screening with tandem mass spectrometry and the past years continue to demonstrate the therapeutic effectiveness of dietary management of the disorder, with patients treated from birth remaining normal and those treated late, ceasing to deteriorate and even improving in cognitive and physical functioning. Finally, prenatal diagnosis appears to be possible as was predicted, but never proven, some years ago.

Mechanism of the beneficial effects of pentoxifylline during sepsis: maintenance of adrenomedullin responsiveness and downregulation of proinflammatory cytokines

BACKGROUND

Although it is known that pentoxifylline (PTX) produces various beneficial effects during sepsis, it remains unknown whether this agent has any salutary effects on the depressed vascular responsiveness to adrenomedullin (ADM), a novel potent vasodilatory peptide, under such conditions.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP). One hour after CLP, PTX (50 mg/kg body wt) or vehicle (normal saline) was infused intravenously over 90 min. Twenty hours after CLP (i.e., the late, hypodynamic stage of sepsis), the thoracic aorta and small intestine were isolated and preconstricted by norepinephrine. Rat ADM (10(-7) M) was applied, and the percentage of ADM-induced relaxation in the aortic rings and resistance vessels in the small intestine was determined. In addition, plasma ADM was determined by radioimmunoassay and tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 levels were measured by enzyme-linked immunosorbent assay.

RESULTS

The percentage of ADM-induced vascular relaxation in the aortic rings and resistance vessels of the isolated gut was significantly reduced 20 h after CLP. Administration of PTX early after the onset of sepsis, however, prevented the decrease in vascular ADM responsiveness at the macro- and microcirculatory levels. Plasma ADM levels increased after CLP, irrespective of PTX infusion, indicating that the effect of PTX was not mediated by altering ADM release. The upregulated TNF-alpha, IL-1beta, and IL-6 during late sepsis were, however, attenuated by PTX administration, suggesting that maintenance of ADM responsiveness by this agent appears to be due to downregulation of these cytokines.

CONCLUSIONS

Since early administration of PTX maintains vascular ADM responsiveness even during the late stage of sepsis, this agent appears to be a useful adjunct in preventing the deterioration in hemodynamics and cardiovascular function during the progression of polymicrobial sepsis.

Reduction in vascular responsiveness to adrenomedullin during sepsis

BACKGROUND

Although sepsis is characterized by an early, hyperdynamic phase followed by a late, hypodynamic phase, the mechanism responsible for the transition from the hyperdynamic to the hypodynamic state remains unknown. Since recent studies have shown that adrenomedullin (ADM), a novel potent vasodilatory peptide, is upregulated during sepsis, the aim of this study was to determine whether the reduced vascular responsiveness to ADM is associated with the transition from the hyperdynamic phase to the hypodynamic phase of sepsis.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 and 10 h (i.e., the hyperdynamic phase of sepsis) or 20 h (the hypodynamic phase) after CLP, the thoracic aorta or small intestine was harvested and preconstricted with norepinephrine. Adrenomedullin (10(-7) M) was applied and the percentage of ADM-induced vascular relaxation in the aortic ring and isolated small intestine was determined.

RESULTS

The responsiveness to ADM in the thoracic aorta was not altered at 5-10 h, but decreased significantly at 20 h after CLP. Although ADM-induced relaxation in resistance blood vessels of the small intestine did not change at 5 h, it decreased markedly at 10 and 20 h after the onset of sepsis.

CONCLUSIONS

Since the transition from hyperdynamic to hypodynamic sepsis takes place between 10 and 20 h after CLP, it is likely that reduced vascular responsiveness to ADM may be responsible for such an event during the course of polymicrobial sepsis. In view of this, maintenance of vascular ADM responsiveness by pharmacologic agents appears to be a novel approach for preventing or delaying the occurrence of hypodynamic sepsis and septic shock.

Upregulation of Kupffer cell beta-adrenoceptors and cAMP levels during the late stage of sepsis

Although a burst of immunoresponsiveness may occur during the early stage of sepsis, late sepsis is characterized by severe immunodepression. In addition, although studies have shown that stimulation of macrophage beta-adrenoceptors results in an increase in cAMP and an associated reduction in macrophage phagocytic activity, it remains unknown whether Kupffer cell beta-adrenoceptor characteristics and cAMP levels are altered during polymicrobial sepsis. To study this, Sprague-Dawley rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 h (i.e., the early stage of sepsis) or 20 h (late sepsis) after CLP or sham operation, the liver was perfused with collagenase solution and Kupffer cells were isolated. beta-Adrenoceptor characteristics of the isolated Kupffer cells were determined using [125I]iodopindolol, and basal levels of cAMP were measured by radioimmunoassay. The results indicate that while maximum binding capacity (Bmax) of Kupffer cell beta-adrenoceptors was not altered at 5 h, it increased significantly at 20 h after CLP. Similarly, basal levels of cAMP in Kupffer cells did not change at 5 h but increased markedly at 20 h after the onset of sepsis. In contrast, the dissociation constant (Kd, 1/affinity) of Kupffer cell beta-adrenoceptors was not significantly affected by sepsis at both 5 h and 20 h after CLP. Thus, upregulation of beta-adrenoceptors and increase in cAMP levels in Kupffer cells occur during the late stage of polymicrobial sepsis, and this may contribute to the depression of macrophage phagocytic function under such conditions.

Stimulation of adenylate cyclase in isolated rat glomeruli by prostaglandins

The effect of prostaglandins and various agents on cyclic adenosine 3',5'-monophosphate generation was studied in isolated rat glomeruli. Specific activity of adenylate cyclase in the glomeruli showed a 12-fold increase over the crude homogenate and a fivefold increase over a tubular preparation. Prostacyclin (PGI2) preferentially stimulated adenylate cyclase of isolated glomeruli at a concentration as low as 10(-9) M. Prostaglandins (PGE1, PGE2, and PGA2) and parathyroid hormone (1-34 synthetic PTH fragment) increased adenylate cyclase in glomeruli with maximal stimulation at 2 X 10(-5) M and 2-4 microgram/ml, respectively. No inhibition of PGE2 on PTH stimulation was observed. Isoproterenol (2 X 10(-4) M) caused a small stimulation, while PGF2alpha, arginine vasopressin, and angiotensin II were ineffective. The presence of guanosine triphosphate in the adenylate cyclase assay enhanced basal and PGE2- and PTH-stimulated activity, but had no effect on NaF stimulation. These findings show an effect of prostaglandins and PTH on the glomerular cAMP system and raise the possibility of a physiological action of these agents on the glomerulus.