Pharmacokinetics and renal excretion of diphenhydramine and its metabolites, diphenylmethoxyacetic acid and diphenhydramine-N-oxide, in developing lambs

The developmental disposition of diphenhydramine (DPHM) and its metabolites, diphenylmethoxyacetic acid (DPMA) and DPHM-N-oxide (DPHMNO), was investigated in postnatal lambs. Lambs received a DPHM intravenous (iv) bolus 15 days (Group A; n = 5) or 2 months (Group B; n = 6) after birth. Total body clearance of DPHM in postnatal lambs (Group A = 138.7 +/- 80.5 mL/min/kg; Group B = 165.7 +/- 51.3 mL/min/kg) was similar to the nonplacental clearance values (i.e., the component of fetal total body clearance that is not due to elimination via the placenta) estimated for fetal lamb (116.3 +/- 49. 6 mL/min/kg), and significantly greater than estimates in adult sheep (38.5 +/- 12.3 mL/min/kg). In addition, Group A DPHM renal clearance (CL(r), >1.80 +/- 1.24 mL/min/kg) was similar to that of the fetus (2.06 +/- 0.24 mL/min/kg), and significantly greater than that for Group B (0.26 +/- 0.17 mL/min/kg) and the adult (0.012 +/- 0.005 mL/min/kg). In contrast, similar to the fetal situation, postnatal DPMA CL(r) (Group A = 0.02 +/- 0.02 mL/min/kg; Group B = 0.05 +/- 0.01 mL/min/kg) was significantly less than adult values (0. 53 +/- 0.19 mL/min/kg). Because DPMA is not sequentially metabolized in sheep, the lower CL(r) in postnatal lambs results in longer apparent elimination half-lives of this metabolite (Group A = 90.4 +/- 32.2 h; Group B = 13.13 +/- 11.0 h) compared with that in the adult (2.9 +/- 1.6 h). No age-related difference in DPHMNO CL(R) was observed. Alterations in the CL(r) of DPHM and DPMA are likely related to differences in the rate of development of mechanisms (i.e. , tubular secretion and reabsorption and glomerular filtration rate) involved in the urinary drug excretion of organic acids and bases.

Neurokinin-1 receptor expression in inflammatory bowel disease: molecular quantitation and localisation

BACKGROUND

Substantial evidence implicates the neuropeptide substance P (SP) in mucosal immunoinflammatory responses. Autoradiographic studies have suggested a disturbance in SP receptor expression in inflammatory bowel disease (IBD).

AIMS

Because of technical limitations such as poor cellular resolution with autoradiography, we used molecular methods to specifically localise the cellular expression of the neurokinin-1 receptor (NK-1R) in IBD colon, and to quantitate NK-1R mRNA expression levels therein.

METHODS

In situ hybridisation and immunohistochemistry were used to localise NK-1R mRNA and protein, respectively, in normal, ulcerative colitis (UC), and Crohn's disease (CD) colonic resections. NK-1R mRNA expression levels of normal, UC, and CD mucosal biopsies were quantitated by competitive reverse transcription-polymerase chain reaction.

RESULTS

NK-1R expression was localised to lamina propria mononuclear cells, epithelium, submucosal vasculature, smooth muscle, and myenteric plexus of normal and IBD colon. No ectopic NK-1R expression was observed in IBD. However, we found increased numbers of NK-1R expressing lymphoid cells in IBD tissue, aberrant negative epithelial expression of NK-1R in UC, and increased expression of NK-1R in CD myenteric plexus. Quantitation of NK-1R mRNA expression in IBD colonic mucosal biopsies revealed marked upregulation of NK-1R mRNA levels compared with non-inflamed mucosal expression levels (p<0.01).

CONCLUSIONS

This report demonstrates the strategic localisation and upregulation of NK-1R expression in IBD colon, and thereby suggests the involvement of substance P in the pathophysiological symptoms of IBD.

Peripheral PYY inhibits intracisternal TRH-induced gastric acid secretion by acting in the brain

The site of action of peripheral peptide YY (PYY)-induced inhibition of vagally stimulated gastric acid secretion was studied using immunoneutralization with PYY antibody in urethan-anesthetized rats. Gastric acid secretion (59+/-7 micromol/90 min) stimulated by intracisternal injection of the stable thyrotropin-releasing hormone (TRH) analog RX-77368 (14 pmol/rat) was dose-dependently inhibited by 52%, 69%, and 83% by intravenous infusion of 0.25, 0.5, and 1.0 nmol. kg(-1) x h(-1) PYY, respectively. PYY or PYY(3-36) (2.4 pmol/rat) injected intracisternally also inhibited the acid response to intracisternal RX-77368 by 73% and 80%, respectively. Intravenous pretreatment with PYY antibody (4.5 mg/rat), which shows a 35% cross-reaction with PYY(3-36) by RIA, completely prevented the inhibitory effect of intravenously infused PYY (1 nmol x kg(-1) x h(-1)). When injected intracisternally, the PYY antibody (280 microg/rat) reversed intracisternal PYY (2.4 pmol)- and intravenous PYY (1 nmol x kg(-1) x h(-1))-induced inhibition of acid response to intracisternal RX-77368 by 64% and 93.5%, respectively. These results provide supporting evidence that peripheral PYY inhibits central vagal stimulation of gastric acid secretion through an action in the brain.

The effect of decreasing digital image resolution on teledermatology diagnosis

OBJECTIVE

To determine the effect of degraded digital image resolution (as viewed on a monitor) on the accuracy and confidence of dermatologic interpretation.

MATERIALS AND METHODS

Eight dermatologists interpreted 180 clinical cases divided into three Logical Competitor Sets (LCS) (pigmented lesions, non-pigmented lesions, and inflammatory dermatoses). Each case was digitized at three different resolutions. The images were randomized and divided into (9) 60-image sessions. The physicians were completely blinded concerning the image resolution. After 60 seconds per image, the viewer recorded a diagnosis and level of confidence. The resultant ROC curves compared the effect of LCS, level of clinical difficulty, and resolution of the digital image. One-way analysis of variance (ANOVA) compared the curves.

RESULTS

The areas beneath the ROC curves did not demonstrate any consistently significant difference between the digital image resolutions for all LCS and levels of difficulty. The only significant effect observed was amongst pigmented lesions (LCS-A) where the ROC curve area was significantly smaller in the easy images at high resolution compared to low and medium resolutions. For all other ROC curve comparisons within LCS-A, at all other levels of difficulty, as well as within the other LCS at all levels of difficulty, none of the differences was significant.

CONCLUSION

A 720 x 500 pixel image can be considered equivalent to a 1490 x 1000 pixel image for most store-and-forward teledermatology consultations.

Ontogeny of valproic acid disposition and metabolism: a developmental study in postnatal lambs and adult sheep

The ontogeny of valproic acid (VPA) disposition and metabolism was investigated in developing lambs and adult sheep (Dorset or Suffolk breed). Specifically, we wished to investigate the role of glucuronidation and beta-oxidation on VPA elimination during development. Catheters were implanted in a carotid artery, a jugular vein, and the urinary bladder in 10-day-old (10 d; n = 8), 1-month-old (1 M; n = 4), and 2-month-old lambs (2 M; n = 5). In adult sheep (n = 5), catheters were implanted in a femoral artery and vein. After the administration of a 10 mg/kg VPA i.v. bolus, serial blood samples and cumulative urine samples were collected for 36 h in the adult ewes and for 72 h in the lambs. Due to saturable protein binding, age-related differences in VPA clearance were more obvious when examining the total body clearance of unbound drug (Cl(u)tb). Mean Cl(u)tb increased significantly with age up to 2 months (10 d = 2.65 +/- 1.16 ml/min/kg; 1 M = 5.11 +/- 2.49 ml/min/kg; 2 M = 12.84 +/- 3.88 ml/min/kg) before decreasing to adult levels (7.73 +/- 2.64 ml/min/kg). Similarly, the urinary recovery of the major metabolite, VPA-glucuronide, was significantly less in 10 d lambs (29.2 +/- 16.0% of the dose) when compared with the adult and 2 M groups (both approximately 74% of the dose). No differences with age were observed in the portion of the dose excreted as the beta-oxidation metabolite, 2-n-propyl-3-oxopentanoic acid. The results suggest that alterations in Cl(u)tb with age may be attributable to postnatal development of enzymes involved in VPA glucuronidation.

Disposition of valproic acid in maternal, fetal, and newborn sheep. II: metabolism and renal elimination

Metabolism and renal excretion of valproic acid (VPA) were examined in maternal, fetal, and newborn sheep to identify the underlying reasons for the previously observed reduced VPA clearance in newborn lambs. Plasma and urine from VPA infusion studies in maternal, fetal, and newborn sheep were analyzed for VPA and its metabolites [VPA-glucuronide; beta-oxidation products: (E)-2-ene, (E)-3-ene, and 3-keto VPA; hydroxylated metabolites: 3-hydroxy, 4-hydroxy, and 5-hydroxy VPA (5-OH VPA); and 4-ene VPA, 4-keto VPA, 2-propylglutaric acid, and 2-propylsuccinic acid] using gas chromatography-mass spectrometry. All measured metabolites were detectable in maternal and fetal plasma, with 3-keto and 5-OH VPA being at higher concentrations in the fetus. Plasma concentrations of (E)-2-ene, (E)-3-ene, 3-keto, and 5-OH VPA were higher in the newborn compared with the mother, whereas those of the other metabolites were similar. A smaller percentage of the dose was excreted as VPA-glucuronide in newborn lamb urine (28.3 +/- 12.0%) compared with the mother (77.0 +/- 7.8%). Similarly, a lower fraction of the dose was excreted unchanged in newborn urine (11.0 +/- 5.8%) relative to the urine of the mother (19.3 +/- 5.8%); however, significantly larger percentages were excreted as (E)-2-ene (0.11 +/- 0.04 versus 0.02 +/- 0.01%), 3-keto (11.6 +/- 3.5 versus 1. 6 +/- 0.8%), 4-hydroxy (6.1 +/- 3.2 versus 2.3 +/- 1.3%), and 5-OH VPA (2.2 +/- 0.6 versus. 0.8 +/- 0.6%). The major reason for the reduced VPA elimination in newborn lambs appears to be impaired renal excretion and glucuronidation capacity. As a result, a larger fraction of the dose is channeled to beta-oxidation and hydroxylation pathways. The beta-oxidation activities are high at birth; this may explain the high plasma concentrations of (E)-2-ene and 3-keto VPA observed in newborn lambs and human newborns exposed to VPA.

Disposition of valproic acid in maternal, fetal, and newborn sheep. I: placental transfer, plasma protein binding, and clearance

Separate 24-h maternal and fetal infusions of valproic acid (VPA) were administered to five pregnant sheep at 125 to 138 days gestation (term approximately 145 days) to determine maternal-fetal disposition. The pharmacokinetics of VPA were also investigated in five newborn 1-day-old lambs after a 6-h drug infusion. Plasma, urine, and amniotic and fetal tracheal fluid samples were analyzed for VPA using gas chromatography-mass spectrometry. During maternal drug infusion, the average steady-state fetal/maternal unbound VPA plasma concentration ratio was 0.81 +/- 0.09. Unbound maternal-to-fetal VPA placental clearance (69.0 +/- 20.2 ml/min/kg) was similar to that in the other direction (61.9 +/- 24.2 ml/min/kg); this indicates passive placental diffusion and intermediate placental permeability of VPA in sheep. Newborn unbound VPA clearance (0.66 +/- 0.28 ml/min/kg) was much lower than in the mother (5.4 +/- 2.7 ml/min/kg) or the fetus (62.1 +/- 22.4 ml/min/kg), and exhibited pronounced Michaelis-Menten characteristics. The elimination half-life of the drug was much longer in the newborn (18.6 +/- 2.6 h) relative to the mother (5.6 +/- 1.4 h) and the fetus (4.6 +/- 1.9 h). Thus, VPA elimination in newborn lambs is much slower as compared with adult sheep, a situation similar to that in humans. Plasma protein binding of VPA was saturable, with similar VPA binding capacities and affinities in maternal and fetal plasma. VPA was extensively displaced from binding sites in the newborn lamb during the first 1 to 2 days of life, possibly because of increased plasma free fatty acid concentrations at birth. Thereafter, newborn plasma appeared to have a similar VPA binding capacity but lower affinity compared with the mother and the fetus.

Pancreatic CCK(B) receptors: their potential roles in somatostatin release and delta-cell proliferation

In rodents, cholecystokinin (CCK) induces pancreatic enzyme secretion and pancreas growth through its CCK(A) receptors. It is unknown whether occupation of the CCK(B) receptors present in pig and human pancreas can cause the same effects. This study evaluates CCK(B) receptor expression in rat, mouse, pig, and fetal human pancreata using Northern blot, Western blot, and immunofluorescence techniques. The reported 2.7-kb CCK(B) receptor mRNA transcript in the rat brain and gastric fundus is absent in pancreas; the message was, however, detected by RT-PCR and by a CCK(B) receptor antibody as an 80-kDa protein present uniquely in islet delta-cells. Proteins of 50 and 80 kDa appear in mouse pancreas, and proteins of 50 and 115 kDa appear in pig and human pancreas, respectively, all localized in islet delta-cells. Gastrin mRNAs are strongly present in fetal rat pancreas, and the hormone is localized in islets; both are repressed 10 days after birth. In conclusion, the CCK(B) receptors are present in pancreas of four species with exclusive location in islet delta-cells. In such a location, they could be indirectly involved in the control of enzyme secretion.

Bias reduction in skewed binary classification with Bayesian neural networks

The Bayesian evidence framework has become a standard of good practice for neural network estimation of class conditional probabilities. In this approach the conditional probability is marginalised over the distribution of network weights, which is usually approximated by an analytical expression that moderates the network output towards the midrange. In this paper, it is shown that the network calibration is considerably improved by marginalising to the prior distribution. Moreover, marginalisation to the midrange can seriously bias the estimates of the conditional probabilities calculated from the evidence framework. This is especially the case in the modelling of censored data.

Effects of allergic inflammation of the nasal mucosa on the severity of rhinovirus 16 cold

BACKGROUND

Despite the strong association of asthma exacerbations with rhinovirus (RV) infection, inoculation of asthmatic subjects with RV only causes small changes in lower airway function, suggesting that RV infection is not itself sufficient to provoke asthma exacerbations.

OBJECTIVE

Our purpose was to test whether allergic inflammation increases the airway response to RV infection.

METHODS

We compared the severity of RV type 16-induced colds in 2 groups of 10 subjects with allergic rhinitis. One group received 3 nasal challenges with allergen and the other received challenges with placebo over the week before nasal inoculation with RV type 16 (4000 tissue culture infective dose 50% per subject). Subjects kept symptom diaries and were assessed with spirometry, methacholine challenge, nasal lavage, and sputum induction on days 2, 4, 7, 10, 15, and 30 after inoculation.

RESULTS

The 2 groups developed equal rates of infection (90%), similar cold symptoms (Jackson score median [interquartile range], 11 [6-33] vs 20.5 [6-42] for allergen and placebo groups respectively, P =.54), and similar changes in cellular profile and in IL-6 and IL-8 concentrations in nasal lavage fluid and induced sputum after RV inoculation. The incubation period was significantly longer in the allergen group (2.5 [1-5.5] vs 1 [1-1] day, P =.03) and the duration of cold symptoms was shorter (5 [4-7] vs 8.5 [6-10] days, P =.008). We also found an inverse correlation between the percent of eosinophils in nasal lavage fluid before inoculation and the severity of cold symptoms (r = -0.58, P =. 008).

CONCLUSION

In subjects with allergic rhinitis, augmented nasal allergic inflammation before inoculation with RV type 16 does not worsen the severity of cold symptoms but delays their onset and shortens their duration.

Cellular expression of the neurokinin 1 receptor in the human antrum

The localization of the neurokinin 1 receptor in rat and guinea pig gastrointestinal tract has been extensively studied but not in human tissues. The present study used antibodies to characterize the cellular expression of neurokinin 1 receptors in human antrum. Cryostat sections (40-80 microm) were immunostained for the neurokinin 1 receptor double labeled with substance P, von Willebrand's factor, c-kit, fibronectin, S-100, serotonin, gastrin and somatostatin. Neurokinin 1 receptor-immunoreactivity was observed on neurons within the myenteric and submucosal plexuses surrounded by substance P-immunoreactive fibers and on von Willebrand's factor-immunoreactive endothelial cells lining blood vessels throughout the antral wall. c-Kit-immunoreactive interstitial cells of Cajal and gastrin cells were co-stained by the monoclonal neurokinin 1 receptor antibody. Finally, there was no evidence for the presence of the neurokinin 1 receptor on fibroblasts, Schwann, somatostatin, serotonin or smooth muscle cells. This study clearly demonstrates an expanded cellular expression of the neurokinin 1 receptor in the human antrum.

Glycation impairs high-density lipoprotein function

AIMS/HYPOTHESIS

To examine the effects of incubation of high-density lipoprotein (HDL) under hyperglycaemic conditions on several functions of HDL in vitro.

METHODS

Human HDL (5 mg protein) was incubated for 1 week at 37 degrees C in the presence or absence of 25 mmol/l glucose. Additional samples of human HDL were incubated in butylated hydroxytoluene to control for oxidation.

RESULTS

High-density lipoprotein incubated for 1 week in 25 mmol/l glucose had significant increases in the glycation product, fructoselysine and in the advanced glycation end product, N epsilon-(carboxymethyl)-lysine. High-density lipoprotein apolipoprotein AI and AII concentrations were not altered but glycated HDL had a 65% reduction in paraoxonase enzymatic activity. Glycated HDL did not inhibit monocyte adhesion to human aortic endothelial cells in response to oxidised low-density lipoprotein in vitro (43 +/- 4 monocytes bound vs 21 +/- 2 monocytes for control HDL, p < 0.0001). Hepatic lipase-mediated non-esterified fatty acid release from HDL lipids was enhanced in glycated HDL compared with control HDL (25 +/- 1 vs 16 +/- 1 nmol non-esterified fatty acid hydrolysed/min, respectively, p < 0.0001). Direct glycation of purified paraoxonase protein by incubation in 25 mmol/l glucose caused a 40% reduction in enzymatic activity. This glycated paraoxonase did not inhibit monocyte adhesion to human aortic endothelial cells in vitro (68 +/- 3 monocytes vs 49 +/- 2 monocytes bound for control paraoxonase, respectively, p < 0.001). We also measured a 40% reduction in paraoxonase activity in patients with Type II (non-insulin-dependent) diabetes mellitus and documented coronary artery disease compared with non-diabetic subjects, p < 0.0001.

CONCLUSIONS/INTERPRETATION

Alterations in function of HDL caused by exposure to hyperglycaemic conditions could contribute to the accelerated atherosclerosis observed in Type II diabetes.

Somatostatin receptor subtype 2A expression in the rat retina

Somatostatin is mainly expressed by sparsely occurring amacrine and interplexiform cells in the retina. In this study, we characterized the expression and cellular localization of one of the somatostatin subtype (sst) receptors, sst2A, in the rat retina. The presence of sst2A receptor messenger RNA in retinal extracts was demonstrated by reverse transcription-polymerase chain reaction using specific primers to detect the sst2 receptor and its isoforms, sst2A and sst2B. Specific sst2A receptor immunoreactivity was mainly localized to the plasma membrane of several neuronal cell types. In the outer retina, immunoreactivity was localized to cone photoreceptors, horizontal cells, and rod and cone bipolar cells. Double-label experiments showed the co-localization of sst2A receptor and protein kinase C (alpha and beta), a rod bipolar cell marker, and of sst2A receptor and Calbindin-D28k, a horizontal cell marker. In the inner retina, sst2A receptor immunoreactivity occurred in tyrosine hydroxylase-positive amacrine cells; most were of medium to large size. These findings indicate that somatostatin may act at a distance, in a paracrine manner, on several cell types that express the sst2A receptor, and therefore exert a broad modulatory influence on both scotopic and photopic visual pathways.

Hypothermia decreases excitatory neurotransmitter release in bacterial meningitis in rabbits

The excitatory neurotransmitters glutamate (GLU) and aspartate (ASP) are involved in the pathogenesis of neuronal injury in meningitis. Based on past findings that the induction of moderate hypothermia (32-34 degrees C) attenuates the release of GLU in ischemic brain injury, this study was designed to detect if the application of moderate hypothermia decreases the release of excitatory amino acids (EAA) from brain tissue of animals with bacterial meningitis. Also examined was whether meningitis induces the expression of 72-kDa heat shock protein (HSP 70) in the cerebellum and how hypothermia affects it, for induction of HSP 70 has been used as a sensitive marker of neuronal stress in other forms of brain injury. Meningitis was induced by injecting Group B Streptococcus (GBS) into the cisterna magnae of rabbits. Antibiotic treatment began 16 h later. At this time the animals were anesthetized, instrumented, and randomized to normothermic (Nor) or hypothermic (Hy) conditions. Temperatures were strictly regimented for the following 10 h while maintaining stable cardiorespiratory parameters. Cerebrospinal fluid (CSF) samples were then withdrawn to measure concentrations of bacteria, protein, and amino acids. Meningitis causes CSF contents of GLU and ASP to increase significantly. Hypothermia treated animals demonstrated a 40-50% reduction in CSF GLU and ASP. Meningitis induced the expression of HSP 70 in the cerebellum while hypothermic animals experienced a significant decrease HSP 70 induction. These data demonstrate that hypothermia produces an attenuation of the release of excitatory neurotransmitters in meningitis and suggest that this treatment may attenuate neuronal stress.

Expression of cholecystokinin A receptors in neurons innervating the rat stomach and intestine

BACKGROUND & AIMS

Two distinct receptors, cholecystokinin (CCK)-A and CCK-B, mediate CCK effects in the digestive system. The aim of this study was to elucidate the cellular sites of expression of CCK-A receptor in the rat stomach and small intestine.

METHODS

We developed and characterized an antibody to the N-terminal region (LDQPQPSKEWQSA) of rat CCK-A receptor and used it for localization studies with immunohistochemistry.

RESULTS

Specificity of the antiserum was demonstrated by (1) detection of a broad band at 85-95 kilodaltons in Western blots of membranes from CCK-A receptor CHO-transfected cells; (2) cell surface staining of CCK-A receptor-transfected cells, (3) translocation of CCK-A receptor immunostaining in CCK-A receptor-transfected cells after exposure to CCK; and (4) abolition of tissue immunostaining by preadsorbtion of the antibody with the peptide used for immunization. CCK-A receptor immunoreactivity was localized to myenteric neurons and to fibers in the muscle and mucosa. In the stomach, myenteric neurons and mucosal fibers were abundant. Many CCK-A receptor myenteric neurons contained the inhibitory transmitter vasoactive intestinal polypeptide, and some were immunoreactive for the excitatory transmitter substance P. Subdiaphragmatic vagotomy reduced the density of CCK-A receptor fibers in the gastric mucosa by approximately 50%, whereas celiac/superior mesenteric ganglionectomy had no detectable effect on fiber density.

CONCLUSIONS

CCK-A receptor is expressed in functionally distinct neurons of the gastrointestinal tract. CCK-A receptor may mediate reflexes stimulated by CCK through the release of other transmitters from neurons bearing the receptor.

Differential inhibition of insulin and islet amyloid polypeptide secretion by intraislet somatostatin in the isolated perfused human pancreas

Islet amyloid polypeptide (IAPP) and insulin are co-stored and generally secreted in parallel; however, studies have demonstrated that the IAPP/insulin molar secretory ratio may be altered in response to certain stimuli. Because we previously demonstrated that intraislet somatostatin is an inhibitory regulator of basal insulin secretion in the isolated perfused human pancreas, this study was designed to determine the relative influence on the regulation of IAPP versus insulin secretion. Single-pass perfusion was performed in pancreata obtained from cadaveric organ donors with continuous perfusion of a modified Krebs media with the glucose level maintained at constant 3.9 mM. Intraislet somatostatin was immunoneutralized by the infusion of either a highly sensitive monoclonal somatostatin antibody (SAb) or its FAb fragment (SFAb). Sequential test periods separated by basal periods were performed by infusion of either of the following: glucose, SAb, SFAb, or appropriate controls. IAPP/insulin molar secretory ratio decreased by 33% in response to infusion of either SAb or the SFAb, respectively (p < 0.01), and decreased by 67% in response to glucose infusion (p < 0.01). An alteration of the IAPP/insulin secretory ratio is seen in response to infusion of exogenous glucose or in response to the neutralization of intraislet somatostatin.

Market factors and the availability of community pharmacies

The purpose of this study was to examine the relationships between the availability of community pharmacies and 4 types of market factors. A composite data set was created that linked, at the county level, data on: (1) type and number of pharmacies; (2) population characteristics; (3) payer variables; (4) health care system factors; and (5) competitive factors. In this exploratory study, secondary data were used to assess the association between the availability of community pharmacies and the influence of market factors. To assess the market influences on availability of community pharmacies, 2 regressions were performed. In 1 model, the number of community pharmacies per 10,000 population was the dependent variable, whereas the dependent variable in the other regression was the proportion of independently owned community pharmacies. The independent variables in each regression were the market factors--population characteristics, payer variables, health care system factors, and competitive variables. Squared terms were included for 8 of 15 market factors to account for nonlinearities in the relationships. Multiple market factors were correlated with both the number of community pharmacies and the proportion of independently owned pharmacies in an area. Several of the relationships were not linear and changed direction within the range of data. Counties with either a low or a high percentage of elderly people had fewer pharmacies and a lower proportion of independently owned pharmacies compared with counties with a moderate percentage of elderly people. Counties that were scarcely or highly rural had fewer community pharmacies but a higher proportion of independently owned pharmacies than counties that were moderately rural. Areas with a greater percentage of the population earning less than the poverty level had more pharmacies, especially independently owned ones. Fewer community pharmacies were found in areas with higher health maintenance organization penetration rates. The number of hospital admissions was positively associated with the number of pharmacies but negatively associated with the proportion of independently owned pharmacies. The availability of community pharmacies varies across the country. In light of the trend toward fewer independently owned pharmacies, potential problems in accessing pharmacy services could develop in certain areas, including those that are highly rural and those with a high percentage of people earning less than the poverty level. Future research and policy issues are identified.

Rhinovirus-16 colds in healthy and in asthmatic subjects: similar changes in upper and lower airways

Rhinovirus (RV) infections appear to precipitate most asthma exacerbations. To investigate whether RV-16 induces different inflammatory changes in upper and lower airways of asthmatic and healthy subjects, we inoculated 10 nonatopic healthy and 11 atopic asthmatic adults with 2,000 TCID50 RV-16. Subjects recorded symptoms and peak flow daily; and they underwent spirometry, methacholine challenge (PC20), nasal lavage, and sputum induction at baseline and on Days 2, 4, 15, and 29 d after inoculation. One asthmatic subject developed an exacerbation requiring prednisone treatment 5 d after inoculation. The cold symptom severity (Jackson score) did not differ between groups. During the cold, asthma symptoms increased slightly from baseline in the asthmatic group; and PC20 decreased in the healthy group. However, peak flow, bronchodilator use, and spirometry did not change in either group. At baseline, asthmatics had higher neutrophils, eosinophils, and interleukin (IL)-6 in nasal lavage. After inoculation, both groups developed significant increases in nasal neutrophils, IL-6 and IL-8, and modest increases in sputum neutrophils and IL-6, but not IL-8. However, these changes did not differ between groups. IL-5, interferon-gamma, and RANTES were detected only in nasal lavages from two asthmatic subjects, who had the most severe colds. IL-11 was not detected in any sample. We conclude that inflammatory responses of upper and lower airways during RV-16 colds are similar in asthmatic and healthy subjects, and that RV-16 infection is not by itself sufficient to provoke clinical worsening of asthma.

Hepatic triglyceride lipase promotes low density lipoprotein receptor-mediated catabolism of very low density lipoproteins in vitro

We demonstrate here that hepatic triglyceride lipase (HTGL) enhances VLDL degradation in cultured cells by a LDL receptor-mediated mechanism. VLDL binding at 4 degrees C and degradation at 37 degrees C by normal fibroblasts was stimulated by HTGL in a dose-dependent manner. A maximum increase of up to 7-fold was seen at 10 microg/ml HTGL. Both VLDL binding and degradation were significantly increased (4-fold) when LDL receptors were up-regulated by treatment with lovastatin. HTGL also stimulated VLDL degradation by LDL receptor-deficient FH fibroblasts but the level of maximal degradation was 40-fold lower than in lovastatin-treated normal fibroblasts. A prominent role for LDL receptors was confirmed by demonstration of similar HTGL-promoted VLDL degradation by normal and LRP-deficient murine embryonic fibroblasts. HTGL enhanced binding and internalization of apoprotein-free triglyceride emulsions, however, this was LDL receptor-independent. HTGL-stimulated binding and internalization of apoprotein-free emulsions was totally abolished by heparinase indicating that it was mediated by HSPG. In a cell-free assay HTGL competitively inhibited the binding of VLDL to immobilized LDL receptors at 4 degrees C suggesting that it may directly bind to LDL receptors but may not bind VLDL particles at the same time. We conclude that the ability of HTGL to enhance VLDL degradation is due to its ability to concentrate lipoprotein particles on HSPG sites on the cell surface leading to LDL receptor-mediated endocytosis and degradation.

Trafficking of proteinase-activated receptor-2 and beta-arrestin-1 tagged with green fluorescent protein. beta-Arrestin-dependent endocytosis of a proteinase receptor

Proteases cleave proteinase-activated receptors (PARs) to expose N-terminal tethered ligands that bind and activate the cleaved receptors. The tethered ligand, once exposed, is always available to interact with its binding site. Thus, efficient mechanisms must prevent continuous activation, including receptor phosphorylation and uncoupling from G-proteins, receptor endocytosis, and lysosomal degradation. beta-Arrestins mediate uncoupling and endocytosis of certain neurotransmitter receptors, which are activated in a reversible manner. However, the role of beta-arrestins in trafficking of PARs, which are irreversibly activated, and the effects of proteases on the subcellular distribution of beta-arrestins have not been examined. We studied trafficking of PAR2 and beta-arrestin1 coupled to green fluorescent protein. Trypsin induced the following: (a) redistribution of beta-arrestin1 from the cytosol to the plasma membrane, where it co-localized with PAR2; (b) internalization of beta-arrestin1 and PAR2 into the same early endosomes; (c) redistribution of beta-arrestin1 to the cytosol concurrent with PAR2 translocation to lysosomes; and (d) mobilization of PAR2 from the Golgi apparatus to the plasma membrane. Overexpression of a C-terminal fragment of beta-arrestin-319-418, which interacts constitutively with clathrin but does not bind receptors, inhibited agonist-induced endocytosis of PAR2. Our results show that beta-arrestins mediate endocytosis of PAR2 and support a role for beta-arrestins in uncoupling of PARs.

Substance P-induced trafficking of beta-arrestins. The role of beta-arrestins in endocytosis of the neurokinin-1 receptor

Agonist-induced redistribution of G-protein-coupled receptors (GPCRs) and beta-arrestins determines the subsequent cellular responsiveness to agonists and is important for signal transduction. We examined substance P (SP)-induced trafficking of beta-arrestin1 and the neurokinin-1 receptor (NK1R) in KNRK cells in real time using green fluorescent protein. Green fluorescent protein did not alter function or localization of the NK1R or beta-arrestin1. SP induced (a) striking and rapid (<1 min) translocation of beta-arrestin1 from the cytosol to the plasma membrane, which preceded NK1R endocytosis; (b) redistribution of the NK1R and beta-arrestin1 into the same endosomes containing SP and the transferrin receptor (2-10 min); (c) prolonged colocalization of the NK1R and beta-arrestin1 in endosomes (>60 min); (d) gradual resumption of the steady state distribution of the NK1R at the plasma membrane and beta-arrestin1 in the cytosol (4-6 h). SP stimulated a similar redistribution of immunoreactive beta-arrestin1 and beta-arrestin2. In contrast, SP did not affect Galphaq/11 distribution, which remained at the plasma membrane. Expression of the dominant negative beta-arrestin319-418 inhibited SP-induced endocytosis of the NK1R. Thus, SP induces rapid translocation of beta-arrestins to the plasma membrane, where they participate in NK1R endocytosis. beta-Arrestins colocalize with the NK1R in endosomes until the NK1R recycles and beta-arrestins return to the cytosol.

An immunohistochemical marker for Wallerian degeneration of fibers in the central and peripheral nervous system

This work was prompted by the accidental observation that a newly developed, affinity purified polyclonal antibody against the C-terminus of the neuropeptide tyrosine (NPY) Y1-receptor protein decorates degenerating fibers in the central nervous system (CNS). This staining did not appear in control animals in which the antibody marked perikarya and dendrites at previously described locations [X. Zhang, L. Bao, Z.-Q. Xu, J. Kopp, U. Arvidsson, R. Elde, T. Hökfelt, Localization of neuropeptide Y Y1-receptors in the rat nervous system with special reference to somatic receptors on small dorsal root ganglion neurons, Proc. Natl. Acad. Sci. USA 91 (1994) 11738-11742]. Three models of experimental lesions were studied: sciatic nerve transection, spinal cord transection and parietal cortex thermocoagulation. In each model, animals were divided in groups (n=2) and processed for indirect immunofluorescence at different time intervals up to 28 days post-lesion (PL) (see below). All three experimental lesions produced a very intense immunolabeling of fibers in the projection pathways of the lesioned structures, strongly reminding of Wallerian degeneration (WD). In the sciatic nerve, the staining first appeared on day 1 PL, was strongly increased on day 3 PL, then declined after 7 days and had almost completely disappeared after 14 days. In the CNS, the staining appeared later and was first observed on day 3 PL and remained for a longer period, thus showing different time courses in the brain and spinal cord as compared to the sciatic nerve. The labeling was completely abolished, both in the CNS and in the sciatic nerve, by pre-incubation of the Y1-R antibody with the immunogenic peptide at a dilution of 10-6 M. The appearance of the staining and its time course strongly suggest that the process was related to degenerating axons. Although the protein actually detected remains to be determined, it is suggested that the staining ability of this antibody could be used as a positive marker of axonal degeneration following experimental or naturally occurring lesions of the nervous system.

Gelatinase-A (MMP-2), gelatinase-B (MMP-9) and membrane type matrix metalloproteinase-1 (MT1-MMP) are involved in different aspects of the pathophysiology of malignant gliomas

Matrix metalloproteinases (MMPs) have been implicated as important factors in gliomas since they may both facilitate invasion into the surrounding brain and participate in neovascularization. We have tested the hypothesis that deregulated expression of gelatinase-A or B, or an activator of gelatinase-A, MT1-MMP, may contribute directly to human gliomas by quantifying the expression of these MMPs in 46 brain tumour specimens and seven control tissues. Quantitative RT-PCR and gelatin zymography showed that gelatinase-A in glioma specimens was higher than in normal tissue; these were significantly elevated in low grade gliomas and remained elevated in GBMs. Gelatinase-B transcript and activity levels were also higher than in normal brain and more strongly correlated with tumour grade. We did not see a close relationship between the levels of expression of MT1-MMP mRNA and amounts of activated gelatinase-A. In situ hybridization localized gelatinase-A and MT1-MMP transcripts to normal neuronal and glia, malignant glioma cells and blood vessels. In contrast, gelatinase-B showed a more restricted pattern of expression; it was strongly expressed in blood vessels at proliferating margins, as well as tumour cells in some cases. These data suggest that gelatinase-A, -B and MT1-MMP are important in the pathophysiology of human gliomas. The primary role of gelatinase-B may lie in remodelling associated with neovascularization, whereas gelatinase-A and MT1-MMP may be involved in both glial invasion and angiogenesis. © 1999 Cancer Research Campaign