Exploring why young African American women do not change condom-use behavior following participation in an STI/HIV prevention intervention.

Human immunodeficiency virus (HIV) interventions can significantly reduce risky sexual behaviors among vulnerable populations. However, not everyone exposed to an intervention will reduce their sexual risk behavior. This qualitative study sought to identify factors associated with young African American females' lack of increase in condom use post-participation in an HIV prevention intervention. Semi-structured interviews were conducted with 50 young African American women (18-23 years; approximately half were mothers) after participating in a demonstrated effective HIV prevention intervention; 24 did not increase condom use post-intervention. Interviews were thematically coded for barriers to condom-use post-intervention. Although nearly all young women reported partner-associated challenges to using condoms, there were relational differences observed among those who changed their condom use versus those who did not. Many 'non-changers' were engaged in non-stable 'on and off' relationships, with high rates of infidelity, often with the father of their child, in which they were fearful of requesting condom use. 'Non-changers' also reported more substance use, feeling incapable of change and not thinking about condom use. Thus, future HIV prevention efforts may benefit from incorporating strategies on how young mothers can maintain a non-sexual relationship with their child's father, as well as elaborating on the intersection of substance use and risky sexual decision-making.

Aerosol delivery of star polymer-siRNA nanoparticles as a therapeutic strategy to inhibit lung tumor growth.

Lung cancer is a major contributor to cancer-related death worldwide. siRNA nanomedicines are powerful tools for cancer therapeutics. However, there are challenges to overcome to increase siRNA delivery to solid tumors, including penetration of nanoparticles into a complex microenvironment following systemic delivery while avoiding rapid clearance by the reticuloendothelial system, and limited siRNA release from endosomes once inside the cell. Here we characterized cell uptake, intracellular trafficking, and gene silencing activity of miktoarm star polymer (PDMAEMA-POEGMA) nanoparticles (star nanoparticles) complexed to siRNA in lung cancer cells. We investigated the potential of nebulized star-siRNA nanoparticles to accumulate into orthotopic mouse lung tumors to inhibit expression of two genes [ßIII-tubulin, Polo-Like Kinase 1 (PLK1)] which: 1) are upregulated in lung cancer cells; 2) promote tumor growth; and 3) are difficult to inhibit using chemical drugs. Star-siRNA nanoparticles internalized into lung cancer cells and escaped the endo-lysosomal pathway to inhibit target gene expression in lung cancer cells in vitro. Nebulized star-siRNA nanoparticles accumulated into lungs and silenced the expression of ßIII-tubulin and PLK1 in mouse lung tumors, delaying aggressive tumor growth. These results demonstrate a proof-of-concept for aerosol delivery of star-siRNA nanoparticles as a novel therapeutic strategy to inhibit lung tumor growth.

Synthesis and self-assembly of brush-type poly[poly(ethylene glycol)methyl ether methacrylate]-block-poly(pentafluorostyrene) amphiphilic diblock copolymers in aqueous solution.

Well-defined fluorinated brush-like amphiphilic diblock copolymers of poly[poly(ethylene glycol)methyl ether methacrylate] (P(PEGMA)) and poly(pentafluorostyrene) (PPFS) have been successfully synthesized via atom transfer radical polymerization (ATRP). The self-assembly behavior of these polymers in aqueous solutions was studied using (1)H NMR, fluorescence spectrometry, static and dynamic light scattering and transmission electron microscopy techniques. The micellar structure comprised of PPFS as the core and brush-like (hydrophobic main chain and hydrophilic branches) polymers as the coronas. The hydrodynamic radius (R(h)) of the micelles in aqueous solution was in the nanometer range, independent of the polymer concentration, consistent with a closed association model. Diblock copolymers with a longer P(PEGMA) block formed micelles with smaller R(h) and lower aggregation numbers consistent with an improved solubilization of the core. The micelles possessed a thick hydration layer as verified by the ratio of the radius of gyration, R(g) to the hydrodynamic radius, R(h). The aggregation number and ratio of R(g) to R(h) were observed to increase with temperature (20-50 degrees C), while the R(h) of the micelle decreased slightly over the same temperature range. An increase in temperature induced the brush-like PEG segments in the corona to dehydrate and shrink while forming micelles with larger aggregation numbers.

Micelle formation and gelation of (PEG-P(MA-POSS)) amphiphilic block copolymers via associative hydrophobic effects.

A series of well-defined amphiphilic di- and triblock copolymers have been synthesized, using atom transfer radical polymerization, with poly(ethylene glycol) (PEG) and poly(methacrylisobutyl polyhedral oligomeric silsesquioxane) P(MA-POSS) as the hydrophilic and hydrophobic blocks, respectively. The detailed self-assembly behavior of the amphiphilic macromolecules in aqueous media was studied using both static and dynamic light scattering (SLS and DLS) techniques. The evolution of block copolymer micelle formation in THF/water mixture (20/80 v/v) was monitored as the THF evaporated from the solvent mixture. Initially the block copolymer chains existed as unimers in solution, followed by the formation of smaller aggregates (R(h) < 2 nm) after 30 min, eventually growing in size to reach an equilibrium size when all the THF evaporated within 24 h. The micelles formed by the block copolymers were found to be kinetically unstable (not frozen); i.e., they tended to revert to individual copolymer chains on dilution. The hydrodynamic radii, R(h), of the micelles varied with the degree of polymerization (DP) of the hydrophobic P(MA-POSS); for example, for PEG(5K)-b-P(MA-POSS), an increase from R(h) approximately 13.3 +/- 1.1 nm to R(h) approximately 17.5 +/- 1.4 nm was observed with a nominal change in the DP of P(MA-POSS) from 4 to 6. The micelles formed by the triblock copolymers (P(MA-POSS)-b-PEG(10K)-b-P(MA-POSS)) were comparable in size to the diblock copolymer micelles; e.g., R(h) approximately 14.0 +/- 1.3 nm was found for P(MA-POSS)(4)-b-PEG(10K)-b-P(MA-POSS)(4). The micellar structures created by the triblocks in aqueous media were "flowerlike", where the PEG middle block adopted a loop conformation in the micelle corona. In addition to micelles, larger aggregates formed by P(MA-POSS)-b-PEG(10K)-b-P(MA-POSS) were also detected in solution. The larger aggregates may suggest a contribution from some PEG blocks adopting an extended conformation with one end dangling in solution, causing gelation at higher copolymer concentrations via intermicellar interactions. The P(MA-POSS)(4)-b-PEG(10K)-b- P(MA-POSS)(4) formed a gel in water at approximately 8.8 wt % copolymer concentration. No gel formation by diblock copolymers was observed; however, the addition of a small amount of triblock copolymer to an aqueous solution of diblock copolymer results in gel formation. Finally, rheological behavior of the obtained gels was also investigated.

Stathmin mediates neuroblastoma metastasis in a tubulin-independent manner via RhoA/ROCK signaling and enhanced transendothelial migration.

Neuroblastoma, the most common solid tumor of young children, frequently presents with aggressive metastatic disease and for these children the 5-year survival rates are dismal. Metastasis, the movement of cancer cells from one site to another, involves remodeling of the cytoskeleton including altered microtubule dynamics. The microtubule-destabilizing protein, stathmin, has recently been shown to mediate neuroblastoma metastasis although precise functions remain poorly defined. In this study we investigated stathmin's contribution to the metastatic process and potential mechanism(s) by which it exerts these effects. Stathmin suppression significantly reduced neuroblastoma cell invasion of 3D tumor spheroids into an extracellular matrix. Moreover, inhibiting stathmin expression significantly reduced transendothelial migration in two different neuroblastoma cell lines in vitro. Inhibition of ROCK, a key regulator of cell migration, in neuroblastoma cells highlighted that stathmin regulates transendothelial migration through ROCK signaling. Reduced stathmin expression in neuroblastoma cells significantly increased the activation of the RhoA small GTPase. Notably, re-expression of either wild type or a phospho-mimetic stathmin mutant (4E) made defective in tubulin binding returned cell migration and transendothelial migration back to control levels, indicating that stathmin may influence these processes in neuroblastoma cells independent of tubulin binding. Finally, stathmin suppression in neuroblastoma cells significantly reduced whole body, lung, kidney and liver metastases in an experimental metastases mouse model. In conclusion, stathmin suppression interferes with the metastatic process via RhoA/ROCK signaling in neuroblastoma cells. These findings highlight the importance of stathmin to the metastatic process and its potential as a therapeutic target for the treatment of neuroblastoma.

Molecular physiology and pathophysiology of tight junctions in the blood-brain barrier.

Disruption of the tight junctions (TJs) of the blood-brain barrier (BBB) is a hallmark of many CNS pathologies, including stroke, HIV encephalitis, Alzheimer's disease, multiple sclerosis and bacterial meningitis. Furthermore, systemic-derived inflammation has recently been shown to cause BBB tight junctional disruption and increased paracellular permeability. The BBB is capable of rapid modulation in response to physiological stimuli at the cytoskeletal level, which enables it to protect the brain parenchyma and maintain a homeostatic environment. By allowing the "loosening" of TJs and an increase in paracellular permeability, the BBB is able to "bend without breaking"; thereby, maintaining structural integrity.

Development of an antibody to actinomycin D and its application for the detection of serum levels by radioimmunoassay.

An antibody specific for actinomycin D (Act D) has been developed and used in a rapid, sensitive radioimmunoassay for detection of this anticancer drug in serum. The 2-amino group of the heterocyclic chromophore of Act D was covalently coupled to available free carboxyl groups of bovine serum albumin with carbodiimide. The resulting complex was then used for the production of a specific antibody to Act D in two male New Zealand rabbits. Antibody production was of sufficient titer in both rabbits to allow the development of a radioimmunoassay for the free drug which is rapid and sensitive enough to accurately measure 0.1 pmol of Act D. The antibody produced was characterized to be immunoglobulin G by virtue of its ability to bind to Protein A:Sepharose columns. With the use of Act-D analog, actinomine, the antibody was characterized to be specific for the pentapeptide portion of the molecule. Pharmacokinetic analysis of serial serum samples obtained from a patient who received the drug i.v. revealed a biphasic response with an alpha-serum half-life of 1.78 and a beta serum half-life of 34 min. An i.v. injection of Act D into a dog and assay of serum concentration revealed a similar biphasic response with an alpha serum half-life of 0.78 min and a beta-serum half-life of 208 min.

Disposition of mitoxantrone in cancer patients.

We have used a highly sensitive high-performance liquid chromatographic assay to evaluate the pharmacokinetics and tissue disposition of mitoxantrone, an investigational anthracene derivative which has shown significant activity during Phase II clinical trials in the treatment of metastatic breast cancer, unfavorable histology non-Hodgkin's lymphoma, and acute leukemia. Mitoxantrone (12 mg/sq m over 30 to 35 min in 250 ml of dextrose 5% in water) and 14C-labeled mitoxantrone (specific activity, 8.85 muCi/mg) were administered to eight patients who had advanced soft tissue cancers. The plasma disappearance of mitoxantrone concentrations measured by high-performance liquid chromatography was best described by a three-compartment model with a mean t alpha of 0.1 h, a t beta of 1.1 h, and a t gamma of 42.6 h. The mean apparent Vc was 12.2 liters/sq m, while the mean Vd was 1875 liters/sq m. The mean plasma clearance was 0.57 liters/min/sq m, and the mean renal clearance was 45 ml/min/sq m. Only 6.5% of the total mitoxantrone dose was excreted in the urine as unchanged drug over 5 days. The mean recovery of 14C-labeled material in feces over 5 days was 18.3% of the administered dose. Thirty-five days after mitoxantrone administration to a patient who died of progressive kidney cancer, approximately 15% of the 14C dose could be accounted for in seven major organs. We conclude that mitoxantrone appears to distribute into a deep tissue compartment from which it is slowly released. These data provide a pharmacological rationale for use of mitoxantrone on an intermittent dosing schedule.

Pharmacokinetics of 13-cis-retinoic acid in patients with advanced cancer.

13-cis-Retinoic acid (13-CRA) is a synthetic analog of vitamin A effective reversing preneoplastic lesions in both humans and animals. To study its physiochemical properties and disposition kinetics, we developed a rapid, sensitive, and precise high-performance liquid chromatography assay for 13-CRA in biological samples. This assay system resulted in a clear separation of 13-CRA from all-trans-retinoic acid and retinol and had a detection limit of 20 ng/ml plasma. Recovery was 89 +/- 6% (S.D.) at equivalent physiological concentrations with a precision of 8%. To study the disposition kinetics in humans, 13 patients received a p.o. bolus of 13-CRA and had blood samples collected at timed intervals. For the 10 patients studied on the first day of 13-CRA administration, the mean time to peak plasma concentration was 222 +/- 102 min. Interpatient peak 13-CRA plasma concentrations were found to be variable, suggesting irregular gastrointestinal absorption. Beta-Phase t 1/2 was approximately 25 hr. The prolonged terminal-phase plasma half-life may represent biliary excretion and enterohepatic circulation.

Ectoenzymes as sites of peptide regulation.

The ectoenzyme-mediated metabolism of neuropeptides may be an important regulatory site of peptide-mediated activity. These membrane-bound, extracellularly oriented peptidases are not only responsible for inactivating peptide substrates, but also lead to the formation of metabolic fragments. Peptide fragments formed after enzymatic proteolysis have been shown to display novel bioactivity as a consequence of a shift in receptor selectivity. This example of nervous system plasticity through peptide biotransformation can have multiple consequences. Centrally acting drugs have been shown to have profound effects on peptide-mediated systems throughout the brain and spinal cord including a differential alteration in ectoenzyme activity and ectoenzyme-mediated metabolism of neuropeptides. In this review, Tom Davis and Chris Konkoy suggest that the modulation of ectoenzyme-mediated peptide metabolism represents an additional level at which the concentration of extracellular neuropeptides, and thus peptide-mediated transmission, can be regulated.

Cholesterol embolization: clinical findings and implications.

The clinical characteristics of 13 patients with cholesterol embolization are described. Embolization occurred spontaneously in 2 patients and after a vascular procedure in 11. Acute but vague symptoms were reported by 11 of the 13 patients; skin findings of purple toes or livedo reticularis and renal dysfunction were present in 12 patients, 5 of whom required dialysis. Blood pressure elevation occurred in all 13 patients, eosinophilia in 9 of 10 and elevated sediment rate in 5 of 6. Death occurred within 6 months in three patients. Two distinct patterns were observed: mild (five patients) and severe (eight patients). Compared with the severe pattern, patients with mild cholesterol embolization had early symptoms less frequently (two of five versus eight of eight), less severe renal insufficiency (serum creatinine 1.7 versus 7.4 mg/100 ml), less of an increase in blood pressure (22 versus 34 mm Hg) and later development of skin lesions (14 versus 6 weeks). Baseline blood pressure and development of eosinophilia were comparable in both groups. The presentation of cholesterol embolization is often subtle and may go unrecognized, particularly in its mild form. As vascular interventions increase in elderly atherosclerotic and hypertensive patients, so too will the incidence of this disorder.

Time-dependent sensitization of plasma beta-endorphin in community elderly with self-reported environmental chemical odor intolerance.

This study examined plasma beta-endorphin as a marker of the physiological stress response in community elderly who were either high (n = 15) or low (n = 15) in self-rated frequency of illness from environmental chemical odors. Individuals who report nonatopic multiple sensitivities to or intolerances for low levels of environmental chemicals also claim high rates of comorbid food sensitivities or intolerances. Subjects gave 9 AM blood samples for plasma beta-endorphin 90 min after ingesting either 1% fat cow's milk or a soy-based nondairy drink, on six different mornings in the laboratory after all-night sleep recordings. The six sessions-were divided into three sets of two successive days each, with each set [involving baseline (ad lib milk), nondairy (soy-based), and dairy diets] separated from the next by 3 weeks. In the chemically tolerant subjects, stably lower beta-endorphin levels suggested that milk may have been a physiologically less stressful beverage than was the soy drink. In contrast, the chemical odor intolerant group exhibited a) increased levels of plasma beta-endorphin averaged over the 6 days (p = .02); and b) marked fluctuations in endorphin from one laboratory day to the next (Group x Diet x Day interaction, p = .005). The findings were consistent with time-dependent, context-dependent sensitization of beta-endorphin in the chemical odor intolerant individuals.

Antihypertensive effects of parenteral nicardipine alone and in combination with captopril.

We studied the safety and efficacy of intravenous nicardipine alone and in combination with oral captopril. Sixteen patients with essential hypertension received a single oral dose of captopril, 50 mg, to be certain that excessive hypotension would not occur. Nicardipine was given intravenously as a 2 mg bolus, followed by an infusion at a rate designed to lower the supine diastolic blood pressure at least 10 mm Hg; then oral captopril, 50 mg, or placebo was given. The next week, nicardipine was again infused, but the alternate oral treatment was given. Intravenous nicardipine reduced blood pressure from 156 +/- 15/101 +/- 5 mm Hg (mean arterial blood pressure 120 +/- 6 mm Hg) to 140 +/- 11/88 +/- 4 mm Hg (mean arterial blood pressure 105 +/- 5 mm Hg). When captopril was added to nicardipine, the mean arterial blood pressure fell an additional 8 mm Hg but the heart rate did not increase. The combination of angiotensin-converting enzyme inhibition and calcium channel blockage produces additive antihypertensive effects without additional reflex tachycardia.

Regulation of CCK mRNA in the human neuroepithelioma cell line SK-N-MCIXC in response to second messenger activators.

Regulation of cholecystokinin (CCK) expression was studied in the human neuroepithelioma cell line SK-N-MCIXC. The cells were treated with the phosphodiesterase inhibitor isobutyl-methylxanthine and the tumor promoting phorbol ester, phorbol-12-myristate 13-acetate; activators of the cyclic AMP (cAMP) and protein kinase C (PKC) second messenger pathways, respectively. Levels of CCK mRNA were determined after 6, 12 and 24 hour drug treatments, with Northern blot analysis using human CCK cDNA hybridization probes. Activation of both cAMP and PKC second messenger pathways increased CCK mRNA levels in SK-N-MCIXC cells. These results indicate that the levels of CCK mRNA in SK-N-MCIXC cells are regulated by cAMP and PKC dependent mechanisms.

Prohormone convertase and autocrine growth factor mRNAs are coexpressed in small cell lung carcinoma.

A hallmark of small cell lung carcinoma (SCLC) is the expression of autocrine growth factors such as neurotensin and gastrin-releasing peptide, which bind to cellular receptors and stimulate cell division. The biological activity of autocrine growth factors requires the concurrent expression of prohormone convertases that cleave the growth factors to their active form, suggesting the expression of these genes is linked in SCLCs. RNase protection assays were used to detect the expression of autocrine growth factor and prohormone convertase mRNAs in a panel of lung cancer cell lines. These mRNAs are coexpressed in SCLC and lung carcinoid cell lines, but not in normal lung epithelium or in non-small cell lung cancers. These findings, together with earlier results from our laboratory, suggest the expression of prohormone convertases has an important role in the development and maintenance of the SCLC phenotype and that autocrine growth factor and prohormone convertase genes respond to a common transcriptional activator in SCLC.

[L-Ala3]DPDPE: a new enkephalin analog with a unique opioid receptor activity profile. Further evidence of delta-opioid receptor multiplicity.

To investigate delta-opioid receptor topography near the 3-position of [D-Pen2,D-Pen5]enkephalin (DPDPE), a series of small-group 3-position analogs of DPDPE have been synthesized and assayed for binding potencies and in vitro biological activities. L-Amino acid substitutions at this position are highly favored over D-amino acid substitutions, with the smallest, [L-Ala3]DPDPE (DPADPE), being the most favored in the series investigated. [L-Ala3]DPDPE is nearly as delta-potent and more delta-selective in both rat brain binding (18 nM vs [3H] [p-ClPhe4]DPDPE and mu/delta = 610) and peripheral bioassays (12 nM in the MVD and GPI/MVD = 4500) when compared to DPDPE (8.5 nM, mu/delta = 73 and 4.1 nM, GPI/MVD = 1800, respectively). Whereas DPDPE is a potent analgesic when given icv, [L-Ala3]DPDPE is only a weak analgesic. However, [L-Ala3]DPDPE has been found to antagonize DPDPE, but not Deltorphin II, in a moderately potent (pA2 = 5.7) and selective fashion in vivo. Thus, [L-Ala3]DPDPE is a fairly potent agonist at peripheral delta receptors and is a moderately potent (mixed) antagonist of delta 1 receptors in the brain. It appears that [L-Ala3]DPDPE does not interact in any significant manner with delta 2 or mu receptors in the brain.

Enkephalin glycopeptide analogues produce analgesia with reduced dependence liability.

Endogenous peptides (e.g. enkephalins) control many aspects of brain function, cognition, and perception. The use of these neuroactive peptides in diverse studies has led to an increased understanding of brain function. Unfortunately, the use of brain-derived peptides as pharmaceutical agents to alter brain chemistry in vivo has lagged because peptides do not readily penetrate the blood-brain barrier. Attachment of simple sugars to enkephalins increases their penetration of the blood-brain barrier and allows the resulting glycopeptide analogues to function effectively as drugs. The delta-selective glycosylated Leu-enkephalin amide 2, H(2)N-Tyr-D-Thr-Gly-Phe-Leu-Ser(beta-D-Glc)-CONH(2), produces analgesic effects similar to morphine, even when administered peripherally, yet possesses reduced dependence liability as indicated by naloxone-precipitated withdrawal studies. Similar glycopeptide-based pharmaceuticals hold forth the promise of pain relief with improved side-effect profiles over currently available opioid analgesics.

Effects of cyclic flexion of coronary arteries on progression of atherosclerosis.

The purpose of this investigation was to test the hypothesis that cyclic flexion of the coronary arteries contributes to the progression of atherosclerotic plaques. Coronary arteriograms were evaluated in 33 unselected patients who underwent 2 studies over a period of 25 +/- 16 months (mean +/- SD). Among the 33 patients, 103 plaques were identified. Plaques that showed progression were compared with plaques that showed no progression. The angle of flexion that occurred during systole at the site of the plaque was measured on the first arteriogram. In comparing progression versus no progression, the interval between arteriograms was 29 +/- 18 versus 23 +/- 14 months (p = NS) and percent stenosis at the first arteriogram was 42 +/- 28 versus 45 +/- 19% (p = NS). Percent stenosis at the time of the second arteriogram among plaques that progressed was 78 +/- 21%, and by definition, it remained 45 +/- 19% among those that did not progress. Among arteries with plaques that showed a progression of stenosis, the angle of flexion during systole was 19 +/- 13 degrees versus 9 +/- 15 degrees among arteries with plaques that did not progress (p < 0.01). Linear regression showed that the correlation of the angle of flexion with percent change of stenosis was relatively low (r = 0.32) but statistically significant (p < 0.005). Mathematic modeling of flexible and stiff plaques showed stresses approximately 1.5 to 1.9 times greater with 20 degrees than with 10 degrees flexion. Stresses due to flexion were usually greatest proximal and distal to the plaque along the subendothelial layer of the inner wall of the curved vessel. Data show that the angle of cyclic flexion, and consequently the stresses due to cyclic flexion of the artery were greatest in the region of plaques that progressed over the period of observation. Such stresses may have contributed to tissue damage of fatigue resulting in a more rapid progression of the atheromatous plaques.

Peptidases in the CNS: formation of biologically active, receptor-specific peptide fragments.

Peptides function as chemical signals between cells of multicellular organisms, or different organisms, via specific receptors on target cells. Many hormones, neuromodulators, and growth factors are peptides. Because there is no known reuptake system for peptides at the nerve terminal, the biological activity of peptides in the extracellular space is regulated by enzymatic degradation and extracellular metabolism. For example, angiotensin I is processed extracellularly in the lung by angiotensin-converting enzyme (ACE; E.C. 3.4.15.1), a peptidyl dipeptidase, to form the potent vasoconstrictor hormone angiotensin II. When neuropeptides are released from neurons into the extracellular space, specific peptidases also can modulate the peptidergic signal by generating smaller, biologically active fragments via products with similar or dissimilar characteristics of the parent peptide. Therefore, receptor-binding selectivity of a released peptide hormone can be regulated by peptidases. Because peptidases may play a key role in the extracellular regulation of peptidergic signaling, alterations in peptidase activities by drugs or disease states may lead to disruptions in biological homeostasis. The subject of this article is the role of peptidases in the central nervous system in the formation of biologically active, receptor-specific peptides from peptide E, beta-endorphin, neurotensin, and cholecystokinin.

Neuroleptic drug treatment alters in vitro central neurotensin metabolism.

Neurotensin (NT) has been shown to possess pharmacological properties associated with neuroleptic drugs. To determine if chronic haloperidol (HL; 3.5 mg/kg/day) or chlorpromazine (CPZ; 4.2 mg/kg/day) treatment affects central NT metabolism, HL and CPZ were perfused via Alzet minipumps into male Sprague-Dawley rats for 8 days. Purified synaptosomal plasma membrane (pSPM) were isolated and time-course incubated with NT (100 microM; 30-120 min). All samples were analyzed by high resolution, reversed-phase high performance liquid chromatography. HL and CPZ caused an increase in NT metabolism at the pSPM. Although an increase in NT metabolism would result in a loss of biological activity, it does lead to a significant accumulation of the biologically active NT fragment NT-(9-13), which has been shown to bind to the NT receptor. Therefore, neuroleptic drug treatment alters NT metabolism at the pSPM, leading to the formation of a fragment with antinociceptive activity.