Disparities in diabetes and hypertension care for individuals with serious mental illness.

OBJECTIVES: People with serious mental illnesses (SMI), including schizophrenia, bipolar disorder, and major depression, experience early mortality, partly due to comorbid physical health conditions such as diabetes and hypertension. This study examined the quality of diabetes and hypertension care for Medicaid and Medicare enrollees with SMI. STUDY DESIGN: We conducted a retrospective analysis of medical records and claims data from 3 health plans: a Medicaid plan for disabled adults, a Medicaid plan for low-income adults, and a Special Needs Plan for individuals dually enrolled in Medicaid and Medicare. The study population included 258 adults with SMI and diabetes and 241 adults with SMI and hypertension. METHODS: Existing quality measures for diabetes and hypertension from the Healthcare Effectiveness Data and Information Set (HEDIS) were adapted and applied to the SMI population for the 2012 calendar year. The rates of diabetes care and hypertension control for people with SMI were compared with national averages for Medicaid and Medicare managed care plans to examine disparities in care. RESULTS: Adults with SMI receive poor-quality care for diabetes and hypertension. Depending on the health plan, performance on the diabetes care and hypertension control HEDIS measures was 14 to 49 percentage points lower among the SMI population than the general Medicaid and Medicare populations. CONCLUSIONS: Findings highlight disparities in care for individuals with SMI compared with the general Medicaid and Medicare populations. Health plans demonstrated substantial room for improvement on almost all diabetes and hypertension HEDIS measures for the SMI population.

The Current State of Behavioral Health Quality Measures: Where Are the Gaps?

OBJECTIVE: This review examined the extent to which existing behavioral health quality measures address the priority areas of the National Behavioral Health Quality Framework (NBHQF) as well as the extent to which the measures have received National Quality Forum endorsement and are used in major reporting programs. METHODS: This review identified behavioral health quality measures in widely used measure inventories, including the National Quality Measures Clearinghouse, National Quality Forum, and the Center for Quality Assessment in Mental Health. Additional measures were identified through outreach to federal agencies. Measures were categorized by type, condition, target population, data source, reporting unit, endorsement status, and use in reporting programs. RESULTS: The review identified 510 measures. Nearly one-third of these measures address broad mental health or substance use conditions rather than a specific condition or diagnosis. Seventy-two percent are process measures. The most common data source for measures is administrative claims, and very few measures rely on electronic health records or surveys. Fifty-three (10%) measures have received National Quality Forum (NQF) endorsement, and 28 (5%) unique measures are used in major quality reporting programs. Several subdomains of the NBHQF, such as treatment intensification, financial barriers to care, and continuity of care, lack measures that are NQF endorsed. CONCLUSIONS: Despite the wide array of behavioral health quality measures, relatively few have received endorsement or are used in reporting programs. Future efforts should seek to fill gaps in measurement and to identify the most salient and strongest measures in each priority area.

Users of Medicaid home and community-based services are especially vulnerable to costly avoidable hospital admissions.

Although Medicaid's coverage of home and community-based services and the program's capacity to provide such services have increased markedly in recent years, relatively little is known about the population that uses these services. We combined Medicaid and Medicare data to characterize the national Medicaid population of service users by key demographic and health-related attributes. We also assessed one important dimension of their health outcomes: potentially avoidable hospital admissions. We found that in 2005 there were 2.2 million users of Medicaid home and community-based services-almost 4 percent of the total Medicaid population-and that two-thirds of these users were dually eligible for Medicare and Medicaid. Users of home and community-based services were particularly vulnerable to avoidable hospital admissions, compared to the full Medicaid and US populations, and these hospitalizations occur at substantial cost to public payers. For the dual eligibles using home and community-based services, Medicare pays most of the costs of these avoidable hospital stays. Our findings emphasize the need for further research to establish policies and practices that can best meet the needs of users of Medicaid home and community-based services.

Risk factors associated with the occurrence of fractures in U.S. nursing homes: resident and facility characteristics and prescription medications.

OBJECTIVES: To determine whether resident and facility characteristics and prescription medications influence the occurrence of fractures in nursing homes (NHs). DESIGN: Panel study with 1-year follow-up. SETTING: A nationally representative sample of NHs from the Medical Expenditure Panel Survey (MEPS). PARTICIPANTS: Residents aged 65 and older who were in sample NHs on January 1, 1996. MEASUREMENTS: Health status measures were collected from facility records and abstracted using a computer-assisted personal interview instrument. Fracture and drug data were updated every 4 months to provide a full year of information. Drug data were obtained from monthly medication administration records. The occurrences of fractures were obtained from medical records. Administered medications were classified using the Department of Veterans Affairs medication classification system. Facility characteristics were based on MEPS survey data collected from NH sources. RESULTS: In 1996, 6% of residents in a NH at the beginning of the year experienced a fracture during their NH stay(s). Resident risk factors included aged 85 and older, admitted from the community, exhibited agitated behaviors, and used both wheelchair and cane or walker. Use of anticonvulsants, antidepressants, opioid analgesics, iron supplements, bisphosphonates, thiazides, and laxatives were associated with fractures. A high certified nurse aide ratio was negatively associated with fractures. CONCLUSION: The findings indicate that fractures are associated with resident and facility characteristics and prescribing practices. It reaffirms the importance of medication review with special attention on opioid analgesics, antidepressants, and anticonvulsants to reduce the risk of fractures.

Hospitalization and death associated with potentially inappropriate medication prescriptions among elderly nursing home residents.

BACKGROUND: This study examines the association of potentially inappropriate medication prescribing (PIRx) with hospitalization and death among elderly long-stay nursing home residents. METHODS: We defined PIRx using the combined version of the Beers criteria. Data were from the 1996 Medical Expenditure Panel Survey Nursing Home Component. The study sample included 3372 residents, 65 years and older, who had nursing home stays of 3 consecutive months or longer in 1996. We performed multivariate logistic regression analyses of longitudinal data using generalized estimating equations. RESULTS: Residents who received any PIRx had greater odds (odds ratio [OR], 1.27; P = .002) of being hospitalized in the following month than those receiving no PIRx. Residents with PIRx exposure for 2 consecutive months were at increased risk (OR, 1.27; P = .004) of hospitalization, as were those receiving PIRx in the second month only (OR, 1.80; P = .001), compared with those receiving no PIRx. Residents who received PIRx were at greater risk of death (OR, 1.28; P = .01) that month or the next. Residents with intermittent PIRx exposures were at greater odds of death (OR, 1.89; P<.001), compared with those with no PIRx exposure. CONCLUSIONS: The association of PIRx with subsequent adverse outcomes (hospitalization and death) provides new evidence of the importance of improving prescribing practices in the nursing home setting.

Potentially inappropriate medication prescriptions among elderly nursing home residents: their scope and associated resident and facility characteristics.

OBJECTIVE: To estimate the scope of potentially inappropriate medication prescriptions (PIRx) among elderly residents in U.S. nursing homes (NHs), and to examine associated resident and facility characteristics. DATA SOURCES: The 1996 Medical Expenditure Panel Survey Nursing Home Component (MEPS NHC), a survey of a nationally representative sample of NHs and residents. STUDY DESIGN: The PIRx, defined by Beers's consensus criteria (1991, 1997), was identified using up to a year's worth of NH prescribed medicine data for each resident. The study sample represented 1.6 million NH residents (n=3,372). RESULTS: At a minimum, 50 percent of all residents aged 65 or older, with an NH stay of three months or longer received at least one PIRx in 1996. The most common PIRx involved propoxyphene, diphenhydramine, hydroxyzine, oxybutynin, amitriptyline, cyproheptadine, iron supplements, and ranitidine. Resident factors associated with greater odds of PIRx were Medicaid coverage, no high school diploma, and nondementia mental disorders. Facility factors were more beds and lower RN-to-resident ratio. Factors associated with lower odds of PIRx were fewer medications, residents with communication problems, and being in an accredited NH. Onsite availability of pharmacists or mental health providers was not related. IMPLICATIONS: With quality of care and patient safety as major public health concerns, effective policies are needed to avoid PIRx occurrences and improve the quality of prescribing among elderly residents in NHs. Additional studies are needed to determine the impact of PIRx on this NH population.

Distribution and muscle-sparing effects of clenbuterol in hindlimb-suspended rats.

Based on their anabolic properties in skeletal muscles, beta-adrenergic agonists are of interest as potential countermeasures to microgravity-induced skeletal muscle atrophy. The levels of clenbuterol (Cb), a beta(2)-adrenergic agonist, in both plasma and skeletal muscle were higher in hindlimb-suspended rats than in their nonsuspended Cb-treated controls. Cb treatment was shown to help maintain the body weight in suspended rats, while reducing the amount of mesenteric fat. However, hindlimb suspension attenuated Cb's lipolytic effects. In skeletal muscle, the magnitude of response to unloading and Cb treatment followed a general regional pattern and was muscle and type specific. The highest magnitude of response to unloading was in predominantly slow-twitch muscles, and the least responsive were the predominately fast-twitch muscles.

Central imidazoline (I(1)) receptors modulate aqueous hydrodynamics.

The purpose of this work is to determine the relative contributions of central imidazoline (I(1)) receptors to the ocular hydrodynamic action of moxonidine. Moxonidine (MOX), an alpha(2) and I(1) receptor agonist, and efaroxan (EFA), a relatively selective I(1) antagonist, were utilized to study alterations in intraocular pressure (IOP) and aqueous flow in New Zealand white rabbits subjected to intracerebroventricular (i.c.v.) cannulation and sympathectomy. Intracerebroventricular administration of MOX (0.033, 0.33 and 3.33 microg) to normal rabbits produced dose-dependent, bilateral IOP decreases of 3, 6, and 8 mmHg, respectively. The ocular hypotensive response to MOX was immediate (10 min. post drug), lasted for one hour, and was inhibited by prior administration of efaroxan (3.33 microg i.c.v.). In unilaterally sympathectomized (SX) rabbits, the ocular hypotensive response induced by i.c.v MOX in the denervated eye was attenuated approximately 50%, but the duration of ocular hypotension in the surgically altered eye was longer than that of the normal eye. MOX (0.33 microg i.c.v.), caused a statistically significant decrease (2.24 to 1.59 ml/min.) in aqueous flow in normal eyes. In SX eyes, there was no change in aqueous flow by MOX, suggesting that IOP effect in i.c.v. MOX observed in the SX eye might be mediated by changes in outflow resistance. Sedation was observed in all the rabbits treated with MOX (i.c.v.) and was dose-dependent. These in vivo data support the suggestion that centrally located I(1) receptors modulate the early contralateral response to topically administered MOX and are involved in lowering of IOP and aqueous flow in rabbit. In addition, expression of the full ocular hypotensive effect of centrally applied MOX depends on intact sympathetic innervation. Ocular hypotension induced by MOX in the SX eye may involve an effect on uveoscleral outflow.

Biphasic alterations of cAMP levels and inhibition of norepinephrine release in iris-ciliary body by bremazocine.

Kappa-opioid receptor agonists have been shown to reduce intraocular pressure in rabbits and monkeys. This study was designed to investigate mechanisms in the iris-ciliary body (ICB) that may be involved in bremazocine (BRE)-induced ocular hypotension in New Zealand White rabbits. Using ICBs, BRE and norbinaltorphimine (nor-BNI), relatively selective kappa-opioid receptor agonist and antagonist, respectively, along with pertussis toxin (PTX), were used to evaluate the effect of 1) kappa-opioid receptors on [(3)H]norepinephrine (NE) release from postganglionic sympathetic neurons, and 2) cAMP accumulation. BRE caused dose-related (0.1, 1, and 10 microM) inhibition of electrically stimulated [(3)H]NE release from ICBs to 77, 57, and 36% of the control, respectively. Nor-BNI antagonized the inhibition of [(3)H]NE release by BRE, while PTX pretreatment limited the suppressive effect of BRE (1 and 10 microM). When used alone, BRE (0.01, 0.1, 1, and 10 microM) caused stimulation of cAMP levels in ICBs, however, similar concentrations caused inhibition of isoproterenol (ISO)-stimulated cAMP production. Pretreatment of ICBs with nor-BNI (10 microM) or PTX (150 ng/ml) antagonized BRE-induced suppression of ISO-stimulated cAMP. These data demonstrate that BRE acts at multiple [prejunctional (neuronal) and postjunctional] sites in the ICB. BRE had a biphasic effect on ISO-stimulated adenylyl cyclase activity; enhancing cAMP levels at low concentrations and inhibiting cAMP production at high concentrations. Based on the modifications induced by PTX pretreatment, the kappa-opioid receptors involved in some of the ocular actions of BRE are linked to a G(i/o) protein.

Kappa opioid agonist-induced changes in IOP: correlation with 3H-NE release and cAMP accumulation.

Opioid receptors have been demonstrated to modulate various functions in the eye. This research project was designed to determine and compare the effects of kappa opioid agonists on selected parameters that influence ocular hydrodynamics. Experiments determined the effects of two relatively selective kappa opioid receptor agonists, ICI 204 448 (ICI), which has limited ability to penetrate the blood-brain barrier, and spiradoline mesylate on: (1) in vivo parameters, intraocular pressure (IOP) and pupil diameter (PD); and (2) in vitro parameters, neurotransmitter release and cAMP accumulation, in the ciliary body. Dark-adapted, reverse light cycle New Zealand white (NZW) male rabbits were used in all experiments. In in vivo experiments, intraocular pressures and pupil diameters were measured by a pneumatonometer and an optistick, respectively, before and after drug administration. Baseline readings were taken at 0.5 and 0 hr prior to agonist administration. Postdrug IOP and PD measurements were made at 0.5, 1, 2, 3, 4 and 5 hr after agonist application. In some experiments, the relatively selective kappa antagonist, norbinaltorphimine was applied 30 min prior to agonist application. In in vitro experiments, the release of tritiated norepinephrine (3H-NE) was measured from perfused electrically stimulated iris ciliary bodies and expressed as the percent change of the control. Basal and isoproterenol-stimulated cyclic AMP concentrations in iris ciliary bodies were quantified by radioimmunoassay techniques in the presence and absence of ICI and spiradoline. ICI and spiradoline decreased IOP in a dose-dependent manner in normal rabbits, but only spiradoline produced significant changes in PD. The kappa opioid receptor antagonist, norbinaltorphimine, antagonized the hypotensive effects of spiradoline and ICI in IOP experiments. Both kappa agonists inhibited the release of norepinephrine from perfused iris ciliary bodies. Isoproterenol- stimulated cAMP levels in iris ciliary bodies were suppressed by both kappa receptor agonists. The antagonism by norbinaltorphimine suggests that ICI and spiradoline lower IOP by activating kappa opioid receptors in the eye. The bilateral effects of unilaterally applied spiradoline on PD indicate that this kappa agonist activates receptors in the iris and/or the brain. The inhibition of norepinephrine release and cAMP accumulation in the iris ciliary body by ICI and spiradoline suggests that there are both pre- and postjunctional sites of action for kappa agonists.

Naphazoline-induced suppression of aqueous humor pressure and flow: involvement of central and peripheral alpha(2)/I(1) receptors.

The objective of this study was to examine the ocular hydrodynamic effects of topically and centrally administered naphazoline, alone and following pretreatment with pertussis toxin (PTX) and alpha(2)/I(1)receptor antagonists. Topically and intracisternally administered naphazoline was examined for its ability to alter intraocular pressure (IOP) of rabbits in the absence and presence of receptor antagonists (rauwolscine, efaroxan) and a G(i/o)ribosylating agent PTX. In addition, the topical effects of naphazoline on pupil diameter and aqueous humor flow rate were evaluated. Topical unilateral application of naphazoline (7.5, 25 and 75 micro g; 25 micro l) elicited an ipsilateral dose-dependent mydriasis (2, 4 and 5.5 mm) that peaked at 2 hr with a duration of up to 5 hr. The IOP decreases induced by naphazoline were bilateral and dose-dependent (3, 6 and 10 mmHg); the response peaked at 1 hr and lasted for up to 5 hr. Pretreatment with efaroxan (250 micro g) elicited significantly greater antagonism of the ocular hypotensive response to naphazoline than did rauwolscine (250 micro g) suggesting an involvement of imidazoline (I(1)) receptors. Intracisternal application of naphazoline (3.3 micro g) also produced bilateral reductions (6 mmHg) of IOP that were immediate (10 min post drug) and lasted for approximately 2 hr. In PTX-pretreated (2.5 micro g kg(-1), i.a.) rabbits, the ocular hypotensive effects of naphazoline by both routes (topically and centrally) were attenuated by 50--65%. In addition to producing ocular hypotension, topical application of naphazoline (75 micro g; 25 micro l) caused significant reduction, from 2.8 to 1.5 micro l min(-1), in aqueous humor flow. These in vivo data indicate that, regardless of route of administration, alteration of aqueous humor flow by naphazoline was induced by the activation of alpha(2)and I(1)receptors. The ocular hypotensive effects produced by central administration did not result in sedation, therefore, there is the suggestion that central alpha(2)adrenergic receptors were stimulated minimally by naphazoline. Thus, these data suggest that ocular hypotensive effects and suppression of aqueous humor flow rate by naphazoline are mediated, in part, by alpha(2)and/or central I(1)at both central (brain) and peripheral (eye) sites. Moreover, these data indicate that the receptors are linked to PTX-sensitive G((i/o))proteins.

Elevation of atrial natriuretic peptide levels in aqueous humor of the rabbit by kappa opioid receptor agonists.

Following the topical administration of three kappa agonists (bremazocine, spiradoline and ICI 204448) to rabbit eyes, aqueous humor samples were analyzed for levels of atrial natriuretic peptide (ANP). Bremazocine (BRE) and spiradoline (SPR) elevated aqueous ANP levels in a dose-dependent manner. In contrast, ICI had no significant effect on ANP levels in aqueous humor. Nor-binaltorphimine (nor-BNI), a selective kappa opioid receptor antagonist, was used to assess kappa opioid receptor involvement and glibenclamide, an ATP-sensitive K+ channel blocker, was used to test for the role of ATP-sensitive potassium channels in ANP release. Pretreatment with nor-BNI antagonized the increases in ANP levels observed with both BRE and SPR. Likewise, glibenclamide suppressed the stimulation of ANP secretion by bremazocine. In summary, BRE and SPR increased ANP levels in aqueous humor of rabbits, in part, via activation of K+(ATP) channels that are assumed to be associated with kappa opioid receptors.

Functional identification of phosphodiesterase activity in human trabecular meshwork cells.

The phosphodiesterases (PDE) activity in human trabecular meshwork cells (HTM-3) was investigated in this study in order to better understand the signal transduction pathways in the conventional outflow tract of the eye. Agonists (isoproterenol or nitroprusside) were used to stimulate adenylyl cyclase and guanylyl cyclase, respectively, in the absence and presence of nonselective IBMX or PDE5 specific inhibitors E4021 (1). The subcellular distribution of cAMP and cGMP PDEs was determined directly by PDE enzyme assays using HTM-3 cells. Levels of cyclic nucleotides were measured in the same cells by radioimmunoassay (RIA). Isoproterenol alone elevated cAMP levels, and this response was enhanced by IBMX. Nitroprusside alone caused no increase in basal cGMP levels but, in the presence of E4021, nitroprusside produced significant, dose-related elevation of cGMP levels. Subcellular distribution experiments indicated that the greatest activity for PDEs resided in the supernatant fraction. In conclusion, HTM-3 cells contain PDEs that degrade both cyclic nucleotides. The PDE activities reside predominantly in the supernatant, but the PDE activity for degrading cGMP is more pronounced. Moreover, results with E4021 suggest that PDE5 activity could play a critical role in modulating cGMP-related activity in the trabecular meshwork.

Beta-agonist-induced alterations in organ weights and protein content: comparison of racemic clenbuterol and its enantiomers.

Clenbuterol is a relatively selective beta2-adrenergic partial agonist that has bronchodilator activity. This drug has been investigated as a potential countermeasure to microgravity- or disuse-induced skeletal muscle atrophy because of presumed anabolic effects. The purpose of this study was to: 1) analyze the anabolic effect of clenbuterol's (-)-R and (+)-S enantiomers (0.2 mg/kg) on muscles (cardiac and skeletal) and other organs; and 2) compare responses of enantiomers to the racemate (0.4 mg/kg and 1.0 mg/kg). Male Sprague Dawley rats were treated with: a) racemic clenbuterol (rac-clenbuterol, 0.4 or 1.0 mg/kg); b) enantiomers [clenbuterol (-)-R or (+)-S]; or c) vehicle (1.0 mL/kg buffered saline). Anabolic activity was determined by measuring tissue mass and protein content. HPLC teicoplanin chiral stationary phase was used to directly resolve racemic clenbuterol to its individual enantiomers. In skeletal muscle, both enantiomers had equal anabolic activity, and the effects were muscle- and anatomic region-specific in magnitude. Although the enantiomers did not affect the ventricular mass to body weight ratio, clenbuterol (+)-S induced a small but significant increase in ventricular mass. Both clenbuterol enantiomers produced significant increases in skeletal muscle mass, while being less active in producing cardiac ventricular muscle hypertrophy than the racemic mixture.

Mechanisms and sites of ocular action of 7-hydroxy-2-dipropylaminotetralin: a dopamine(3) receptor agonist.

The purpose of this study was to investigate mechanism(s) and site(s) of action involved in 7-hydroxy-2-dipropylaminotetralin (7-OH-DPAT)-induced ocular hypotension. As measured by pneumatonometry, the topical, unilateral application of 7-OH-DPAT (75 microg), a dopamine D(3)-preferring receptor agonist, decreased the intraocular pressure (IOP) bilaterally. The ocular hypotensive activity of 7-OH-DPAT was diminished in sympathetically denervated rabbits. Pretreatment with raclopride, a D(2)/D(3) receptor antagonist; UH232, a D(3) receptor antagonist; or U-99194A, a D(3) receptor antagonist antagonized 7-OH-DPAT-induced ocular hypotension. However, pretreatment with spiperone, a D(2) receptor antagonist, did not affect the 7-OH-DPAT-induced ocular hypotension. In addition, topically applied 7-OH-DPAT caused a reduction of aqueous humor flow rate. To examine sites of action, immunohistochemistry of D(3) dopamine receptors was performed. Dopamine D(3) receptors were found to be present on postganglionic sympathetic nerves in the ciliary body of normal rabbits but were virtually undetectable in the same tissue of sympathectomized rabbits. In summary, the IOP-lowering effect caused by 7-OH-DPAT was due, in part, to the suppression of aqueous humor flow. Immunohistochemical identification of D(3) receptors in the ciliary body, associated with the diminution of IOP-lowering effects by D(3) receptor agonist 7-OH-DPAT in sympathetically denervated rabbits provided evidence of neuronal site of action of 7-OH-DPAT. Suppression of 7-OH-DPAT-induced ocular hypotension by D(3) receptor antagonists (U-99194A and UH232) and sympathectomy, coupled with the immunohistochemical data, suggested that the primary site of D(3) receptor-mediated action of 7-OH-DPAT is located on postganglionic sympathetic nerve endings in the ciliary body of rabbit.

Modulation of ocular hydrodynamics and iris function by bremazocine, a kappa opioid receptor agonist.

This study was designed to determine the activity of bremazocine (BRE), a relatively selective kappa opioid receptor agonist, on intraocular pressure (IOP), aqueous humor formation and pupil diameter (PD) in conscious, normal, dark-adapted New Zealand white (NZW) rabbits. IOP was measured in normal and unilaterally sympathectomized rabbits using a calibrated pneumatonometer and the aqueous flow rate was determined by the use of a Fluorotron Master. A masked-design study was conducted in which the rabbits' eyes were treated with BRE topically and unilaterally; the fellow eyes received vehicle. IOP and PD measurements were taken at 0.5 hr and 0 time before BRE and 0.5, 1, 2, 3, 4 and 5 hr post-treatment. Fluorophotometry recordings were taken at 1 hr before and 0.5, 1.5, 2.5 and 3.5 hr after topical application of the drug or vehicle. The effect of the relatively selective kappa opioid receptor antagonist, nor-binaltorphimine (nor-BNI), on bremazocine-induced changes in IOP, PD and aqueous flow was also determined. BRE (10 and 100 micrograms 25 microliters-1 vehicle) produced dose-related, bilateral reductions in IOP, PD and aqueous humor flow. A large increase in IOP (14 mmHg) was observed when BRE (100 micrograms) was applied to sympathectomized eyes. This ocular hypertensive effect was antagonized when the sympathectomized eyes were pretreated with naloxone (200 micrograms), a non-selective opioid receptor antagonist. BRE (10 and 100 micrograms) decreased the aqueous humor flow rate bilaterally by approximately 48 and 60%, respectively, at 0.5 hr after administration to the ipsilateral eye. Nor-BNI (100 micrograms) antagonized the effect of BRE (10 micrograms) on IOP and aqueous flow rates more effectively than on PD. These data indicate that bremazocine causes reductions in IOP by suppressing aqueous flow, but the ocular hypotensive effects are dependent on the presence of intact sympathetic nerves. Antagonism of BRE's effects on aqueous humor dynamics by nor-BNI suggests that the mechanism of IOP and aqueous flow reduction may involve, in part, an action on kappa receptors. Further experiments are necessary to fully define the opioid receptor populations in the ciliary body.

Comparative analytical quantitation of clenbuterol in biological matrices using GC-MS and EIA.

A simple and sensitive procedure utilizing GC-MS for the identification and quantitation of clenbuterol in biofluids and tissues is described. This improved method utilizes trimethylboroxine for the derivatization of clenbuterol, requires only 1 mL/g of biological sample, and most importantly does not require an extra cleaning step for urine specimens prior to extraction. Linear quantitative response curves have been generated for derivatized clenbuterol over a concentration range of 5-200 ng/mL. The extraction efficiency at four representative points of the standard curve exceeded 90% in both specimen types (plasma and urine). Linear regression analyses of the standard curve in both specimen types exhibited correlation coefficients ranging from 0.997 to 1.000. The Limit of detection (LOD) and Limit of quantitation (LOQ) values for plasma specimens were determined to be 0.5 and 1.5 ng/mL respectively. For urine specimens, LOD and LOQ values were 0.2 and 0.7 ng/microL respectively. Percentage recoveries ranged from 91 to 95% for urine and 89 to 101% for plasma. Precision and accuracy (within-run and between-run) studies reflected a high level of reliability and reproducibility of the method. In addition to its reliability, sensitivity and simplicity, this modified procedure is more efficient and cost effective, requiring less time, only 1 mL of sample, and minimal amounts of extraction solvents. The applicability of the method for the detection and quantitation of clenbuterol in biological tissues of rats treated with the drug was demonstrated successfully. For comparative analysis of clenbuterol in plasma and liver samples, both GC-MS and enzyme immunoassay (EIA) methods are found to be suitable. Due to potential antibody-cross reactivity with EIA, the GC-MS method is the method of choice for most samples because of its specificity. However, the EIA method is considered the method of choice for analysis of clenbuterol found in concentrations below the limits of quantitation by GC-MS due to its sensitivity.

8OH-DPAT-Induced ocular hypotension: sites and mechanisms of action.

The purpose of this study was to define the ocular actions of 8-OH-DPAT(DPAT), a 5-HT(1A)receptor agonist. The intraocular pressure responses to topically applied DPAT were dose related (25, 125, 250 microgram) and bilateral in normal rabbits but of relatively short duration. Ocular hypotension induced by topical, unilateral DPAT (125 microgram) in normal eyes did not occur in sympathetically denervated eyes. DPAT-induced ocular hypotension was inhibited by pretreatment with spiroxatrine, a 5-HT(1A)and alpha(2C)receptor antagonist, but not spiperone, a 5-HT(2A)receptor antagonist. In contrast, the hypotensive effect produced by unilaterally applied DPAT in the contralateral eye was abolished following pretreatment with rauwolscine, an alpha(2)-receptor antagonist, but the DPAT-induced ocular hypotension was not antagonized in the treated (ipsilateral) eye. Following central administration of DPAT (3 microgram) into the lateral ventricle, intraocular pressure was lowered bilaterally at 10 min and the effect lasted for 2 hr. In in vitro experiments, DPAT (0.1, 1, 10 micrometer) failed to alter norepinephrine release in rabbit iris-ciliary bodies. However, DPAT depressed basal cAMP levels in rabbit iris-ciliary bodies and also caused a dose-related (1, 10, 100 micrometer) inhibition of isoproterenol (1 micrometer)-stimulated cAMP accumulation by 26%, 58% and 82%, respectively. These findings indicate that: (1) based upon bilateral activity by the topical route, DPAT-induced ocular hypotension could result, in part, through activation of 5-HT(1A)receptors in the eye and 5-HT(1A)receptors and/or alpha(2C)adrenoreceptors in the central nervous system, (2) the activity of DPAT on 5-HT(1A)and/or alpha(2C)receptors was confirmed by antagonism of the ocular hypotensive response by spiroxatrine, (3) although there is no apparent prejunctional effect of DPAT on sympathetic nerves of iris-ciliary bodies, the accumulation of basal and isoproterenol-stimulated cAMP levels were depressed by DPAT, and (4) as a result of inhibition by rauwolscine, the ocular hypotensive effect of DPAT in the contralateral eye could involve an action on alpha(2)adrenoreceptors in the central nervous system.

Multiple cyclic nucleotide phosphodiesterases in human trabecular meshwork cells.

PURPOSE: To characterize cyclic nucleotide phosphodiesterase isozyme activities in human trabecular meshwork cells and primary cultures of porcine trabecular meshwork cells. METHODS: Radioimmunoassay of acetylated acid extracts was used to determine changes in cyclic adenosine monophosphate (cAMP) and cyclic quanosine monophosphate (cGMP) in human trabecular meshwork cells treated with phosphodiesterase isoform selective inhibitors. Cyclic nucleotide phosphodiesterase activities were measured using the two-step radioisotope procedure (Thompson). Enzyme activities in the supernatant of human cells were fractionated using anion-exchange chromatography. Additionally, human and porcine trabecular meshwork cell transcripts of phosphodiesterase family-specific isoforms were studied by reverse transcription-polymerase chain reaction and nucleotide sequencing. RESULTS: In intact human cells, selective inhibitors for phosphodiesterase 4 (rolipram) and 5 (E4021) gene families were effective in augmenting cyclic nucleotide accumulation in response to isoproterenol or sodium nitroprusside, respectively. cAMP and cGMP hydrolytic activities, resolved using Trisacryl M anion-exchange chromatography, showed a cAMP phosphodiesterase peak that was minimally sensitivity to cGMP but modestly inhibited by rolipram and a cGMP phosphodiesterase peak that was sensitive to inhibition by E4021. Further evaluation of the cGMP phosphodiesterase demonstrated Michaelis-Menten kinetics and competitive inhibition by E4021. Messenger RNA transcripts for phosphodiesterase 4, 5, and 7 isozymes were isolated in human trabecular meshwork cells. However, in porcine trabecular meshwork cells only isozymes for phosphodiesterase 4 and 5 isozymes were detected. CONCLUSIONS: Human trabecular meshwork cells express phosphodiesterase 4, 5, and 7 gene family isoforms and enzyme activities, suggesting that selective isoform inhibitors could be used to augment the actions of antiglaucoma drugs that use cyclic nucleotides as second messengers.