Apparatus for simultaneous dynamic light scattering-small angle neutron scattering investigations of dynamics and structure in soft matter.

Dynamic Light Scattering (DLS) and Small-Angle Neutron Scattering (SANS) are two key tools to probe the dynamic and static structure factors, respectively, in soft matter. Usually, DLS and SANS measurements are performed separately, in different laboratories, on different samples, and at different times. However, this methodology has particular disadvantages for a large variety of soft materials, which exhibit a high sensitivity to small changes in fundamental parameters, such as waiting times, concentration, pH, and ionic strength. Here, we report on a new portable DLS-SANS apparatus that allows one to simultaneously measure both the microscopic dynamics (through DLS) and the static structure (through SANS) on the same sample. The apparatus has been constructed as a collaboration between two laboratories, each an expert in one of the scattering methods, and was commissioned on the LOQ and ZOOM SANS instruments at the ISIS Pulsed Neutron and Muon Source, U.K.

Volume fraction determination of microgel composed of interpenetrating polymer networks of PNIPAM and polyacrylic acid.

Interpenetrated polymer network microgels, composed of crosslinked networks of poly(N-isopropylacrylamide) and polyacrylic acid (PAAc), have been investigated through rheological measurements at four different amounts of PAAc. Both PAAc content and crosslinking degree modify particle dimensions, mass and softness, thereby strongly affecting the volume fraction and the system viscosity. Here the volume fraction is derived from the flow curves at low concentrations by fitting the zero-shear viscosity with the Einstein-Batchelor equation which provides a parameterkto shift weight concentration to volume fraction. We find that particles with higher PAAc content and crosslinker are characterized by a greater value ofkand therefore by larger volume fractions when compared to softer particles. The packing fractions obtained from rheological measurements are compared with those from static light scattering for two PAAc contents revealing a good agreement. Moreover, the behaviour of the viscosity as a function of packing fraction, at room temperature, has highlighted an Arrhenius dependence for microgels synthesized with low PAAc content and a Vogel-Fulcher-Tammann dependence for the highest investigated PAAc concentration. A comparison with the hard spheres behaviour indicates a steepest increase of the viscosity with decreasing particles softness. Finally, the volume fraction dependence of the viscosity at a fixed PAAc and at two different temperatures, below and above the volume phase transition, shows a quantitative agreement with the structural relaxation time measured through dynamic light scattering indicating that interpenetrated polymer network microgels softness can be tuned with PAAc and temperature and that, depending on particle softness, two different routes are followed.

Neutron diffraction study of aqueous Laponite suspensions at the NIMROD diffractometer.

The process of dynamical arrest, leading to formation of different arrested states such as glasses and gels, along with the closely related process of aging, is central for both basic research and technology. Here we report on a study of the time-dependent structural evolution of two aqueous Laponite clay suspensions at different weight concentrations. Neutron diffraction experiments have been performed with the near and intermediate range order diffractometer (NIMROD) that allows studies of the structure of liquids and disordered materials over a continuous length scale ranging from 1 to 300 Å, i.e., from the atomistic to the mesoscopic scales. NIMROD is presently a unique diffractometer, bridging the length scales traditionally investigated by small angle neutron scattering or small angle x-ray scattering with that accessible by traditional diffractometers for liquids. Interestingly, we have unveiled a signature of aging of both suspensions in the length scale region of NIMROD. This phenomenon, ascribed to sporadic contacts between Laponite platelets at long times, has been observed with the sample arrested as gel or as repulsive glass. Moreover, water molecules within the layers closest to Laponite platelets surface show orientational and translational order, which maps into the crystalline structure of Laponite.

Competing interactions in arrested States of colloidal clays.

Using experiments, theory and simulations, we show that the arrested state observed in a colloidal clay at high concentrations is stabilized by screened Coulomb repulsion (Wigner glass). Dilution experiments allow us to distinguish this disconnected state, which melts upon addition of water, from a low-concentration gel state, which does not melt. Theoretical modeling and simulations at high concentrations reproduce the measured small angle x-ray scattering static structure factors and confirm the long-range electrostatic nature of the arrested structure. These findings are attributed to the different time scales controlling the competing attractive and repulsive interactions.

Good publication practice guidelines for medical communications agencies: a MedComm perspective.

BACKGROUND: Physicians and other health care personnel rely on the peer-reviewed biomedical literature as a key source for making clinical decisions. Thus, ensuring that the nonclinical and clinical findings published in biomedical journals are reported accurately and clearly, without undue influence from commercial interests, is essential. Accordingly, beginning in the mid-1990s and continuing to the present, various organizations, including the International Committee of Medical Journal Editors, the American Medical Association, the Council of Science Editors, the American Medical Writers Association, and the International Society for Medical Publication Professionals, have published guidelines to strengthen and uphold ethical standards in biomedical communications. SCOPE: A task force of staff members from the AXIS group of companies reviewed these and other guidelines to assess the need for a good publication practices (GPP) document specific to medical communications agencies. As this review demonstrated an unmet need, the task force was charged with developing GPP guidelines for the AXIS group of agencies in the United States. FINDINGS: Although such guidelines have been previously published on behalf of medical journal editors and publishers, medical writers, academic centers, and pharmaceutical companies, there has been no prior publication in the peer-reviewed literature of good publication practices for medical communications agencies, which face unique challenges in negotiating a balance among authors, sponsoring companies, and biomedical publishers. CONCLUSION: This article presents and discusses these GPP guidelines. To our knowledge, this is the first publication of guidelines developed from the perspective of a medical communications agency.

Arrested state of clay-water suspensions: gel or glass?

The aging of a charged colloidal system has been studied by small-angle x-ray scattering, in the exchanged momentum range Q=0.03-5 nm(-1) , and by dynamic light scattering, at different clay concentrations (C(w)=0.6-2.8%) . The static structure factor S(Q) has been determined as a function of both aging time and concentration. This is the direct experimental evidence of the existence and evolution with aging time of two different arrested states in a single system simply obtained only by changing its volume fraction: an inhomogeneous state is reached at low concentrations, while a homogeneous one is found at high concentrations.

More on the phase diagram of Laponite.

The phase diagram of a charged colloidal system (Laponite) has been investigated by dynamic light scattering in a previously unexplored range of salt and clay concentrations. Specifically, the clay weight and salt molar concentrations have been varied in the ranges C(w) = 0.004 divided by 0.025 and C(s) = (1 x 10(-3) divided by 5 x 10(-3)) M, respectively. As in the case of free salt water samples (C(s) approximately = 1 x 10(-4) M), an aging dynamics toward two different arrested phases is found in the whole examined C(w) and C(s) range. Moreover a transition between these two different regimes is found. It is clear from these measurements that a revision of the phase diagram is necessary and a new "transition" line between two different arrested states is drawn.

Routes to gelation in a clay suspension.

The gelation of water suspension of a synthetic clay (Laponite) has been studied by dynamic light scattering in a wide range of clay weight concentration (C(w)=0.003-0.031). At variance with previous determination, indicating a stable liquid phase for C(w)

Charge dynamics of 2H- TaSe2 along the less-conducting c-axis.

We present an optical study of 2H-TaSe2 along the less conducting c-axis. This dichalcogenide compound belongs to a large class of conductors called "bad metals" (with a mean free path smaller than the lattice constant along the c-axis), which also includes the superconducting cuprates. The optical response shows the progressive development of a pseudogaplike feature with decreasing temperature. The spectral weight lost by the opening of such a pseudogap goes into the narrow Drude component, developing at low frequency and temperature. There is no violation of the sum rule in 2H-TaSe2 contrary to the cuprates.

Aprotinin decreases exposure to allogeneic blood during primary unilateral total hip replacement.

BACKGROUND: Aprotinin, a hemostatic agent, regulates fibrinolysis, modulates the intrinsic coagulation pathway, stabilizes platelet function, and exhibits anti-inflammatory properties through inhibition of serine proteases, such as trypsin, plasmin, and kallikrein. Aprotinin has been used successfully for many years in cardiac operations, and there have been preliminary investigations of its use in hip replacement operations. The objectives of this multicenter, randomized, placebo-controlled, double-blind trial were to evaluate the efficacy and safety of aprotinin as a blood-sparing agent in patients undergoing an elective primary unilateral total hip replacement and to examine its effect on the prevalence of deep-vein thrombosis in this population. METHODS: Seventy-three patients received a placebo; seventy-six patients, a low dose of aprotinin (a load of 500,000 kallikrein inhibitor units [KIU]); seventy-five, a medium dose of aprotinin (a load of 1,000,000 KIU, with infusion of 250,000 KIU per hour); and seventy-seven patients, a high dose of aprotinin (a load of 2,000,000 KIU, with infusion of 500,000 KIU per hour). The end points for the determination of efficacy were transfusion requirements and blood loss. Patients received standard prophylaxis against deep-vein thrombosis and underwent compression ultrasonography with color Doppler imaging of the proximal and distal venous systems of both legs to evaluate for the presence of deep-vein thrombosis. RESULTS: Aprotinin reduced the percentages of patients who required any form of blood transfusion (47 percent of the patients managed with a placebo needed a transfusion compared with 28 percent of those managed with low-dose aprotinin [p = 0.02],27 percent of those managed with high-dose aprotinin [p = 0.008], and 40 percent of those managed with medium-dose aprotinin [p = 0.5]). Only 6 percent (twelve) of the 212 patients treated with aprotinin required allogeneic blood compared with 15 percent (ten) of the sixty-eight patients treated with the placebo (p = 0.03). Aprotinin decreased the estimated intraoperative blood loss (p = 0.02 for the low-dose group, p = 0.04 for the medium-dose group, and p = 0.1 for the high-dose group), the measured postoperative drainage volume (p = 0.4 for the low-dose group, p = 0.006 for the medium-dose group, and p = 0.000 for the high-dose group), and the mean reduction in the hemoglobin level on the second postoperative day (thirty-four grams per liter for the placebo group, twenty-eight grams per liter for the low-dose group [p = 0.000], twenty-six grams per liter for the medium-dose group [p = 0.000], and twenty-three grams per liter for the high-dose group [p = 0.0001). The rate of deep-vein thrombosis was similar for all groups. CONCLUSIONS: We concluded that aprotinin is safe and effective for use as a hemostatic agent in primary unilateral total hip replacements. In patients who are at high risk of receiving allogeneic blood, use of aprotinin may be of particular clinical and economic benefit.

Incline and length of guiding elements in untreated naturally grown dentition.

The incline and length of guiding elements, i.e. marginal ridges and lingual surfaces of front teeth, marginal ridges and internal cusp slopes of premolars and molars, play an important role in dentistry. Since the so far reported values differ considerably, it was the purpose of the present investigation to replicate the measurements, including all the occlusal landmarks proposed and defined by previous investigators. The measurements were performed on 34 pairs of mounted casts from a selected group of untreated, naturally grown dentitions from adolescents of mean age 14 years. The upper casts were mounted with a face bow, the kinematic hinge axis and the left incisura infraorbitalis representing the posterior and anterior reference points. The lower pinned casts were mounted joint related. All measurements were carried out with a computer-aided, three-dimensional digitizer. The inclines were expressed as angles related to the axis-orbital-plane. Taking the proposed occlusal landmarks as a basis, the inclines of guiding elements were found to be in agreement with previously reported values, despite ethnic and racial differences of the various study-populations. The values, however, differed markedly when measurements based on individual, functional relevant landmarks were compared to measurements based on anatomical, easy identifiable or mathematically constructed landmarks. The successive decrease of the inclines of the guiding elements from the central incisors to the second molars could be confirmed, the molars displaying very flat inclines. Interestingly, 9% of the first molars and 21% of the second molars showed negative values, pointing to a functional arrangement characterized by a buccally oriented occlusal surface of those teeth. Combined with the finding that the length of the guiding elements of the anterior teeth was almost twice as long as that of the posterior teeth, the results corroborate the occlusal concept of an anterior-posterior sequence of the guiding elements, or a so-called sequential guidance with front-canine-dominance.

The effects of metrifonate on the cognitive, behavioral, and functional performance of Alzheimer's disease patients. Metrifonate Study Group.

BACKGROUND: The objective of this study was to evaluate the efficacy and safety of metrifonate, a long-acting acetylcholinesterase inhibitor, in patients clinically diagnosed with probable Alzheimer's disease of mild-to-moderate severity. METHOD: This was a prospective, multicenter, 26-week, double-blind, parallel group study. The 264 randomized patients met diagnostic criteria of the National Institute of Neurological and Communicative Diseases and Stroke and the Alzheimer's Disease and Related Disorders Association for probable Alzheimer's disease. Patients had Mini-Mental State Examination (MMSE) scores of 10-26 and ischemic scores (Rosen modification) of <4. Metrifonate-treated patients received a single 50-mg dose once daily. The efficacy of metrifonate was investigated with respect to 3 symptom domains. Cognitive performance was analyzed using the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) and the MMSE. Psychiatric and behavioral disturbances were analyzed using the Neuropsychiatric Inventory (NPI) and the ADAS-Noncognitive subscale (ADAS-Noncog). The ability to perform instrumental and basic activities of daily living was evaluated using the Disability Assessment for Dementia (DAD) scale. Additionally, global state was assessed using the Clinician Interview-Based Impression of Change with Caregiver Input (CIBIC-Plus) scale. RESULTS: After 26 weeks of metrifonate therapy, a statistically significant benefit of metrifonate was observed in the cognitive performance of Alzheimer's disease patients (ADAS-Cog, t = 2.55, df = 237, p = .012; MMSE, t = 4.60, df = 237, p = .0001). Metrifonate also significantly attenuated the deterioration in activities of daily living of the patients (DAD total score, t = -2.11, df = 233, p = .036) and relieved patients' psychiatric and behavioral disturbances (NPI total score, t = 2.51, df = 233, p = .013). In addition, metrifonate significantly improved the scores for the global state of the patients (CIBIC-Plus, t = 2.07, df = 232, p = .039). Metrifonate was well tolerated; adverse events were predominantly mild in intensity, and no hepatotoxicity was observed. CONCLUSION: In this study, metrifonate was safe and well tolerated. It benefited the cognitive decline, psychiatric and behavioral disturbances, impaired ability to perform instrumental and basic activities of daily living, and global state of patients diagnosed with mild-to-moderate Alzheimer's disease.

Metrifonate benefits cognitive, behavioral, and global function in patients with Alzheimer's disease.

OBJECTIVE: To evaluate the efficacy and safety of metrifonate, an acetylcholinesterase inhibitor, in patients clinically diagnosed with probable Alzheimer's disease (AD) of mild to moderate severity. METHODS: A prospective, 36-week, multicenter, double-blind, randomized, parallel group study of metrifonate in probable AD patients, including a 2-week screening period, a 26-week double-blind treatment period, and a follow-up visit at 8 weeks post-treatment. A total of 24 ambulatory clinics in the United States in a variety of settings, including contract research organizations, public health facilities, and universities. Patients met diagnostic criteria for probable AD as defined by the work group of the National Institute for Neurological and Communicative Diseases and Stroke and the Alzheimer's Disease and Related Disorders Association. Patients had Mini-Mental State Examination (MMSE) scores of 10 to 26 and Ischemic Scores (Rosen Modification) of <4. A total of 408 patients were enrolled. Percentages of patients completing double-blind treatment were 88% and 79% in the placebo and metrifonate groups, respectively. Rates of discontinuation due to adverse events were 4% in the placebo group and 12% in the metrifonate group. Placebo or metrifonate was administered once daily. Metrifonate-treated patients received a loading dose of 100 to 180 mg based on weight (2.0 mg/kg) for 2 weeks, followed by a maintenance dose of 30 to 60 mg based on weight (0.65 mg/kg) for 24 weeks. Primary efficacy variables were the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) and the Clinician's Interview-Based Impression of Change with Caregiver Input (CIBIC-plus). Secondary efficacy variables included the Neuropsychiatric Inventory (NPI), the Disability Assessment in Dementia, the Global Deterioration Scale (GDS), the ADAS-Noncognitive subscale (ADAS-Noncog), the MMSE, and the Clinician's Interview-Based Impression of Severity with Caregiver Input (CIBIS-plus). Outcome measures reflected changes from baseline at week 26 for all variables. Safety was assessed with incidences of premature termination, treatment-emergent events and mortality, and routine safety evaluations. RESULTS: After 26 weeks of metrifonate therapy, a 2.86-point treatment difference (p = 0.0001) was observed in the ADAS-Cog scores of the intent-to-treat AD patients. The treatment difference in the mean CIBIC-plus score at this time was 0.28 points (p = 0.0071). At week 26, treatment differences also were observed in the mean NPI total score (p = 0.0161). Analysis of the remaining secondary efficacy variables showed treatment differences that favored metrifonate but did not reach statistical significance. Metrifonate adverse events were predominantly mild in intensity. No hepatotoxicity was observed. CONCLUSIONS: Metrifonate was safe and well-tolerated. It enhanced not only the cognitive and global function, but also the behavioral function of patients diagnosed with mild to moderate AD. Therefore, metrifonate appears to be useful in the symptomatic treatment of AD.

Pharmacokinetics, pharmacodynamics, and safety of metrifonate in patients with Alzheimer's disease.

Metrifonate is converted nonenzymatically to 2.2, dimethyl dichlorovinyl phosphate (DDVP), an inhibitor of acetylcholinesterase (AChE). This 21-day, randomized, double-blind, placebo-controlled trial of metrifonate in patients with Alzheimer's disease (n = 27) evaluated four doses, each administered orally once daily. All patients received a loading dose (LD) for 6 days followed by a maintenance dose (MD) for 15 days. The treatment groups were: panel 1, LD = 1.5 mg/kg (75-135 mg), MD = 0.25 mg/kg (12.5-25 mg); panel 2, LD = 2.5 mg/kg (125-225 mg), MD = 0.40 mg/kg (20-35 mg); panel 3, LD = 4.0 mg/kg (200-335 mg), MD = 0.65 mg/kg (30-60 mg); and panel 4, LD = 4.0 mg/kg (200-335 mg), MD = 1.0 mg/kg (50-90 mg). All metrifonate doses were well tolerated. Most adverse events were mild to moderate in intensity, gastrointestinal in nature, and transient. Mean area under the concentration-time curve (AUC) and maximum concentration (Cmax) for both metrifonate and DDVP increased in relation to dose. Metrifonate and DDVP had similar, largely dose-independent mean values for time to Cmax (tmax) and half-life (t1/2). There was little or no accumulation of either metrifonate or DDVP with long-term administration. After 21 days of treatment, mean percent erythrocyte AChE inhibition was 14%, 35%, 66%, 77%, and 82% for placebo and panels 1 through 4, respectively. Cognitive improvement was observed with the two highest metrifonate doses. These results reflect favorable safety and pharmacokinetic profiles for the use of metrifonate in the treatment of Alzheimer's disease.

The interleukin-1beta-mediated regulation of proenkephalin and opioid receptor messenger RNA in primary astrocyte-enriched cultures.

Opioids have been found to modulate the function of the immune system by regulating the biochemical and proliferative properties of its cellular components. The interaction of opioid and immune systems, however, is not unidirectional, but rather, bidirectional in nature. In the CNS, one cellular target of immune system activation is the astrocytes, glial cells known to synthesize proenkephalin. We have recently shown that these cells also express the messenger RNA transcripts for the opioid receptors mu, delta and kappa, raising the question of the functional significance of this opioid peptide and the related receptors in the astrocytes. That is, why do astrocytes express proenkephalin and opioid receptors, and are these molecules responsive to a factor to which the astrocytes could be exposed in vivo? Furthermore, do these molecules respond to this factor in a region-specific fashion? In the present study, in order to characterize the astrocytic opioid response to an immune factor, we examined the concomitant regulation of mu, delta, kappa and proenkephalin messenger RNAs by interleukin-1beta (1 ng/ml=60 pM, 24 h) in primary astrocyte-enriched cultures derived from the rat (post-natal day 1-2) cortex, striatum, cerebellum, hippocampus and hypothalamus. Interleukin-1beta treatment was found to increase by 55-75% the level of mu receptor messenger RNA in striatal, cerebellar and hippocampal cultures, but not in cultures derived from the cortex or hypothalamus. However, the cytokine had no effect on the level of delta receptor messenger RNA in any of the five cultures examined. In marked contrast to its stimulatory effects on mu receptor messenger RNA levels and its lack of an effect on 6 receptor messenger RNA expression, interleukin-1beta reduced to 10-30% of control levels the kappa receptor messenger RNA levels in all cultures. Interleukin-1beta had no effect on the level of proenkephalin messenger RNA in cortical, striatal, cerebellar and hypothalamic cultures, but did significantly decrease the expression of proenkephalin messenger RNA in hippocampal cultures to 40% of the control level. Therefore, interleukin-1beta differentially regulated opioid receptor messenger RNA in astrocyte-enriched cultures in a manner dependent upon both the receptor type and the brain region from which the culture was derived. The cytokine also differentially regulated proenkephalin messenger RNA in a region-dependent fashion. These findings suggest a capacity for astrocytes to differentially regulate opioid peptide and receptor messenger RNAs in response to an immune factor, supporting the potential existence of a novel immune-opioid system interaction in the CNS.

Interleukin-1 beta-mediated regulation of mu-opioid receptor mRNA in primary astrocyte-enriched cultures.

Opioids have been found to modulate the immune system by regulating the function of immunocompetent cells. Several studies suggest that the interaction between immune and opioid systems is not unidirectional, but rather reciprocal, in nature. In the CNS, one cellular target of immune system activation is the astrocytes. These glial cells have been shown to produce the opioid peptide, proenkephalin, to express the mu-, delta-, and kappa-opioid receptors, and to respond to the immune factor interleukin-1 beta (IL1 beta) with an increased proenkephalin synthesis. To characterize more completely the astrocytic opioid response to immune factor stimulation, we examined the effect of IL1 beta (1 ng/ml) on the mu-receptor mRNA expression in primary astrocyte-enriched cultures derived from rat (postnatal day 1-2) cortex, striatum, cerebellum, hippocampus, and hypothalamus. A 24-h treatment with IL1 beta produced a 70-80% increase in the mu-receptor mRNA expression in the striatal, cerebellar, and hippocampal cultures but had no effect on this expression in the cortical and hypothalamic cultures. This observation represents one of the few demonstrated increases in levels of the mu-receptor mRNA in vitro or in vivo, since the cloning of the receptor. The enhanced mu-receptor mRNA expression, together with the previous observation that IL1 beta stimulates proenkephalin synthesis in astrocytes, supports the IL1 beta-mediated regulation of an astroglial opioid peptide and receptor in vitro, a phenomenon that may be significant in the modulation of the gliotic response to neuronal damage. Therefore, the astroglial opioid "system" may be important in the IL1 beta-initiated, coordinated response to CNS infection, trauma, or injury.

Primary astroglial cultures derived from several rat brain regions differentially express mu, delta and kappa opioid receptor mRNA.

The existence of opioid receptors within glial cell membranes has been proposed by several laboratories based on biochemical and radioligand binding data. The recent cloning of the mu, delta and kappa receptors has enabled us to directly examine the issue of opioid receptor expression in rat brain astroglia by using solution hybridization/ribonuclease protection assays to analyze the total RNA obtained from primary cultures of cortical, striatal, cerebellar, hippocampal and hypothalamic astrocytes. The results indicate that all five glial cultures expressed mu, delta and kappa receptor mRNA. The rank order of receptor mRNA abundance, expressed collectively across all five cultures, was determined to be delta > or = kappa >> mu. An analysis of the glial distribution profile for each receptor type revealed that mu receptor mRNA levels were the most abundantly expressed in cortical cultures, while the greatest levels of delta receptor mRNA were found in the cortical and hypothalamic cultures, and significant kappa receptor mRNA levels were produced by the cortical, hypothalamic and cerebellar cultures. Furthermore, the five glial cultures each expressed different levels of total opioid receptor (mu + delta + kappa) mRNA. The rank order of total opioid receptor mRNA expression across different astroglial cultures was found to be cortex > hypothalamus > cerebellum = hippocampus > striatum. An analysis of the relative expression profiles for mu, delta and kappa receptor mRNA within each culture revealed that all cultures manifested relatively high levels of delta and kappa receptor mRNA, but relatively low levels of mu receptor mRNA. Generally, cortical, hippocampal and hypothalamic cultures were characterized by comparable levels of delta and kappa receptor mRNA, and little, if any, mu receptor mRNA. However, striatal cultures were characterized by a high level of delta receptor mRNA which was approximately twice and four times that of the kappa and mu receptor mRNA, respectively. In contrast, cerebellar cultures expressed predominantly kappa receptor mRNA at a level which was almost twice that of the delta receptor mRNA, and expressed very little mu receptor mRNA. These data show that primary astroglial cultures not only express mu, delta and kappa receptor mRNAs, but they do so in a manner dependent upon receptor type and brain region. This suggests a regional heterogeneity of astrocytes with respect to opioid receptor expression, a characteristic previously described only for neurons. Furthermore, it suggests the existence of an additional anatomical component in CNS opioid systems.

Differential cellular regulation of pro-opiomelanocortin by interleukin-1-beta and corticotropin-releasing hormone.

Considerable evidence supports the existence of a bidirectional communication between the immune system and the hypothalamo-pituitary-adrenal (HPA) axis. In the present study, we examined the interleukin-1 beta (IL1 beta)-mediated regulation of pro-opiomelanocortin (POMC) at a cellular level, from secretion to gene expression, using murine anterior pituitary corticotroph tumor (AtT20) cells as a model system. The regulatory effects of IL1 beta were compared to those of the classical POMC regulator, corticotropin-releasing hormone (CRH). IL1 beta was found to evoke an early, preferential release of beta-lipotropin (beta LPH) which was accompanied by elevations in POMC heteronuclear (hn)RNA and c-fos and c-jun mRNAs. IL1 beta also elicited a late, preferential release of beta LPH which was associated with only an enhanced expression of POMC hnRNA. Additionally, IL1 beta stimulated an intermediate, preferential release of beta-endorphin (beta E) which was not accompanied by any changes in gene expression. In marked contrast to IL1 beta, CRH evoked an early, preferential beta E secretory response which was associated with elevations in POMC hnRNA and c-fos mRNA. CRH also elicited a late, preferential beta E release which was associated with only an enhanced POMC hnRNA expression. These findings show that although both IL1 beta and CRH activate the corticotrophs, they elicit dramatically different patterns in the regulation of the biochemical dynamics of POMC. Such distinct patterns of corticotroph activation in response to IL1 beta or CRH exposure in vivo would allow the pituitary not only to indicate that it has been activated, but also how it has been activated. This characteristic may be critically important in the function of the HPA axis and in the interaction of the HPA axis with the immune system.