Dose-dependent pharmacokinetics and metabolism of valproic acid in newborn lambs and adult sheep

Dose-dependent pharmacokinetics and metabolism of valproic acid (VPA) were studied in newborn and adult sheep to assess age-related differences in plasma protein binding and metabolic elimination. Newborn lambs received either a 10- (n = 8), 50- (n = 5), 100- (n = 4), or 250-mg/kg (n = 4) VPA i.v. bolus. Individual adult sheep (n = 5) received all four doses in a random order with an appropriate washout period between experiments. Unbound or metabolic clearance of VPA was significantly higher in adult sheep at the two lower doses when compared with lambs, and similar to the lambs at the two higher doses. Plasma protein binding was nonlinear at all doses. Estimates of binding capacity (B(max1)) at the saturable site were higher in adults (91.8 microg/ml) when compared with lambs (44.9 microg/ml), whereas the opposite trend was observed for binding affinity [K(d1) = 9.6 microg/ml (adult) versus 3.2 microg/ml (lambs)]. Characterization of developmental differences in overall VPA metabolic elimination involved fitting of unbound VPA plasma concentration data to a two-compartment model with Michaelis-Menten elimination. This resulted in similar in vivo estimates of apparent V(max) [445.0 microg/min/kg (adult) versus 429.9 microg/min/kg (lambs)]. However, apparent K(m) estimates appeared to be higher in lambs [30.0 microg/ml (adult) versus 69.6 microg/ml (lambs)]. Similar findings were obtained from in vivo estimates of V(max) and K(m) for VPA glucuronidation obtained from VPA-glucuronide metabolite urinary excretion data. Thus, it appears that age-related differences in metabolic clearance may be related to differences in the apparent in vivo K(m) as opposed to V(max) of VPA glucuronidation.

In vivo interactions of apoA-II, apoA-I, and hepatic lipase contributing to HDL structure and antiatherogenic functions

Studies with mice have revealed that increased expression of apolipoprotein A-II (apoA-II) results in elevations in high density lipoprotein (HDL), the formation of larger HDL, and the development of early atherosclerosis. We now show that the increased size of HDL results in part from an inhibition of the ability of hepatic lipase (HL) to hydrolyze phospholipids and triglycerides in the HDL and that the ratio of apoA-I to apoA-II determines HDL functional and antiatherogenic properties. HDL from apoA-II transgenic mice was relatively resistant to the action of HL in vitro. To test whether HL and apoA-II influence HDL size independently, combined apoA-II transgenic/HL knockout (HLko) mice were examined. These mice had HDL similar in size to apoA-II transgenic mice and HLko mice, suggesting that they do not increase HDL side by independent mechanisms. Overexpression of apoA-I from a transgene reversed many of the effects of apoA-II overexpression, including the ability of HDL to serve as a substrate for HL. Combined apoA-I/apoA-II transgenic mice exhibited significantly less atherosclerotic lesion formation than did apoA-II transgenic mice. These results were paralleled by the effects of the transgenes on the ability of HDL to protect against the proinflammatory effects of oxidized low density lipoprotein (LDL). Whereas nontransgenic HDL protected against oxidized LDL induction of adhesion molecules in endothelial cells, HDL from apoA-II transgenic mice was proinflammatory. HDL from combined apoA-I/apoA-II transgenic mice was equally as protective as HDL from nontransgenic mice. Our data suggest that as the ratio of apoA-II to apoA-I is increased, the HDL become larger because of inhibition of HL, and lose their antiatherogenic properties.

[Protective effects of organic acids on human vascular endothelial cells]

OBJECTIVES

In order to examine if organic acids (OA), a kind of natural food components, will prevent from atherosclerosis formation, the effects of four OA, namely chlorogenic acid (CHA), ascorbic acid (AA), citric acid (CA), and malic acid (MA) on human vascular endothelial cells were studied.

METHODS

Primary human umbilical vein endothelial cells (EC) were cultured, and the changes of cell morphology, cell growth, lactate dehydrogenase (LDH) released from cells were measured when EC was incubated with oxidized low density lipoprotein (oxLDL) in the presence or not of four OA added at three different conditions, i.e. before 4 hours oxLDL added, at the same time as oxLDL added, and after 3 hours oxLDL added, as well as at the indicated doses (10, 20 or 40 mg/L).

RESULTS

The EC survival rate of the oxLDL control group was lower (P < 0.01) and LDH release rate was higher (P < 0.01) than those of normal control group. CHA, AA, CA and MA protected EC from damage caused by oxLDL when they were added before and/or at the same time of oxLDL, but the same beneficial effects of these four OA added after oxLDL were not observed. The EC survival rates of CHA + oxLDL and AA + oxLDL groups in three doses were higher (P < 0.05) and the LDH release rates were lower (P < 0.05) in a dose-effect manner when compared with those of oxLDL control group, respectively. Similar results were found in the CA + oxLDL and MA + oxLDL of the high dose groups.

CONCLUSION

Four tested OA could effectively prevent EC from damage induced by oxLDL. CHA and AA had the strongest effects, the next was CA, followed by MA.

Do conventional risk factors predict subclinical coronary artery disease? Results from the Prospective Army Coronary Calcium Project

BACKGROUND

Recent guidelines recommend against the routine use of coronary artery calcification (CAC) detection because the additive value over clinical prediction tools is uncertain. We compared CAC, with use of electron-beam computed tomography (EBCT), with clinical and serologic coronary risk factors for the identification of patients with increased coronary heart disease risk.

METHODS AND RESULTS

We studied 630 active-duty US Army personnel (39-45 years old) without known coronary artery disease (CAD) who were undergoing a routine physical examination as required by regulations. Each participant underwent clinical and serologic risk factor screening and EBCT. The cohort (mean age 42 +/- 2 years, 82% male) had a low predicted risk of coronary events (mean 5-year Framingham risk index [FRI] 1.6% +/- 1.2%). The prevalence of coronary calcification was 17.6% (male 20.6%, female 4.3%). Significant univariate correlates of CAC were total and low-density lipoprotein [LDL] cholesterol, triglycerides, systolic blood pressure, and body mass index. However, only LDL cholesterol was independently associated with CAC. There was a significant but weak relationship between CAC and the Framingham risk index (FRI) (receiver-operator characteristic [ROC] curve area 0.62 +/- 0.03, P <.001), which was not different from the relationship between CAC and LDL cholesterol alone (ROC curve area 0.61 +/- 0.03, P <.001). The prevalence of any CAC in men increased slightly across increasing quartiles of FRI: 17.0%, 20.8%, 33.0%, and 29.2% (P =.033). Other risk factors (family history, homocysteine, insulin, lipoprotein[a], and fibrinogen) were not related to CAC.

CONCLUSIONS

In this age-homogeneous, low-risk screening cohort, conventional coronary risk factors significantly underestimated the presence of premature, subclinical calcified coronary atherosclerosis. These data support the potential of CAC detection as an anatomic, plaque-burden diagnostic test to identify patients who may require more intensive risk-reduction therapies, independent of predicted clinical risk.

High rates of loss of heterozygosity on chromosome 19p13 in human breast cancer

We have recently discovered that the nuclear matrix protein SAFB is an oestrogen receptor corepressor. Since it has become clear that many steroid receptor cofactors play important roles in breast tumorigenesis, we investigated whether SAFB could also be involved in breast cancer. To address this question, the gene locus was examined for structural alterations in breast cancer tissue. Laser capture microdissection was used for isolating DNA from paired primary breast tumour and normal tissue specimens, and the loss of heterozygosity (LOH) at chromosome 19p13.2-3 was determined by use of microsatellite markers. LOH was detected at the marker D19S216, which colocalizes with the SAFB locus, in specimens from 29 (78.4%) of 37 informative patients. The peak LOH rate occurred at D19S216 near the SAFB locus, with LOH frequencies ranging from 21.6% to 47.2% at other markers. The finding of a very high LOH rate at the marker D19S216 strongly indicates the presence of a breast tumour-suppressor gene locus. While preliminary findings of mutations in SAFB suggest that this indeed may be a promising candidate, other potential candidate genes are located at this locus.

Dopa-responsive dystonia simulating spastic paraplegia due to tyrosine hydroxylase (TH) gene mutations

Spastic paraplegia is not widely recognized to occur in dopa-responsive dystonia (DRD). The authors found a compound heterozygote for novel mutations of the human tyrosine hydroxylase (TH) gene (TH). The patient was initially diagnosed as having spastic paraplegia, but responded completely to levodopa therapy. Exercise-induced stiffness in the patient's father, who had a TH deletion, also responded to levodopa. The data expand the clinical spectrum of TH deficiency and suggest that TH mutations may account for some patients with DRD simulating spastic paraplegia.

Transient prenatal expression of NPY-Y1 receptor in trigeminal axons innervating the mystacial vibrissae

Using immunohistochemistry in combination with confocal laser scanning microscopy, we studied the ontogeny of neuropeptide Y-Y1 receptor (Y1-R) expression in the trigeminal system of the rat. The study was limited to the nerve fibers innervating the mystacial pad and the trigeminal ganglia. In the trigeminal ganglia, Y1-R-immunoreactive (IR) neurons were first observed at E16.5. At this same stage some nerve fibers in the trigeminal ganglia also exhibited Y1-R-like immunoreactivity (LI). Strongly Y1-R-IR nerve fibers innervating the follicles of the mystacial vibrissae were first observed at E18. After double labeling, the Y1-R-LI was found to be colocalized with the neuronal marker protein gene product 9.5. At P1 only weak labeling for the Y1-R was found around the vibrissae follicles, whereas the neurons in the trigeminal ganglia were intensely labeled. The same was true for the adult rat, but at this stage no Y1-R labeling at all was observed in nerve fibers around the vibrissal follicles. These results strongly support an axonal localization of the Y1-R at this developmental stage. The transient expression of the Y1-R during prenatal mystacial pad development suggests a role for the Y1-R in the functional development of the vibrissae.

Requirement of cortical actin organization for bombesin, endothelin, and EGF receptor internalization

The role of actin organization in occupancy-induced receptor internalization remains poorly defined. Here we report that treatment of mouse Swiss 3T3 cells with latrunculin A, a potent inhibitor of actin polymerization (including cortical actin), inhibited the internalization of the endogenous bombesin/gastrin-releasing peptide (GRP) receptor, as judged by uptake of (125)I-labeled GRP or fluorescent Cy3-labeled bombesin. In contrast, cells pretreated with cytochalasin D showed minimal inhibition of bombesin/GRP receptor internalization. Similarly, pretreatment of Swiss 3T3 cells with the potent Rho-kinase inhibitor HA-1077, at concentrations (10-20 microM) that abrogated bombesin-mediated stress fiber formation, did not significantly alter receptor-mediated internalization of (125)I-GRP. These results indicate that bombesin/GRP receptor internalization depends on latrunculin A-sensitive cortical actin rather than on rapidly turning over actin stress fibers that are disrupted by either cytochalasin D or HA-1077. The rates and total levels of internalization of the endogenously expressed endothelin A receptor and epidermal growth factor receptor were also markedly reduced by latrunculin A in Swiss 3T3 cells. The potency of latrunculin A for inhibiting G protein-coupled receptor endocytosis was comparable to that for reducing internalization of the epidermal growth factor tyrosine kinase receptor. We conclude that cortical actin structures, disrupted by latrunculin A, are necessary for occupancy-induced receptor internalization in animal cells.

fbpABC gene cluster in Neisseria meningitidis is transcribed as an operon

The neisserial fbpABC locus has been proposed to constitute a single transcriptional unit. To confirm this operonic arrangement, transcription assays using reverse transcriptase PCR amplification were conducted with Neisseria meningitidis. The presence of fbpAB and fbpBC transcripts obtained by priming cDNA synthesis with an fbpC-sequence-specific oligonucleotide indicates that fbpABC is organized as a single expression unit. The ratio of fbpA to fbpABC mRNA was approximately between 10- to 20-fold, as determined by real-time quantitative PCR.

Lipoprotein lipase- and hepatic triglyceride lipase- promoted very low density lipoprotein degradation proceeds via an apolipoprotein E-dependent mechanism

Apolipoprotein E (apoE) is the primary recognition signal on triglyceride-rich lipoproteins responsible for interacting with low density lipoprotein (LDL) receptors and LDL receptor-related protein (LRP). It has been shown that lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) promote receptor-mediated uptake and degradation of very low density lipoproteins (VLDL) and remnant particles, possibly by directly binding to lipoprotein receptors. In this study we have investigated the requirement for apoE in lipase-stimulated VLDL degradation. We compared binding and degradation of normal and apoE-depleted human VLDL and apoE knockout mouse VLDL in human foreskin fibroblasts. Surface binding at 37 degrees C of apoE knockout VLDL was greater than that of normal VLDL by 3- and 40-fold, respectively, in the presence of LPL and HTGL. In spite of the greater stimulation of surface binding, lipase-stimulated degradation of apoE knockout mouse VLDL was significantly lower than that of normal VLDL (30, 30, and 80%, respectively, for control, LPL, and HTGL treatments). In the presence of LPL and HTGL, surface binding of apoE-depleted human VLDL was, respectively, 40 and 200% of normal VLDL whereas degradation was, respectively, 25 and 50% of normal VLDL. LPL and HTGL stimulated degradation of normal VLDL in a dose-dependent manner and by a LDL receptor-mediated pathway. Maximum stimulation (4-fold) was seen in the presence LPL (1 microgram/ml) or HTGL (3 microgram/ml) in lovastatin-treated cells. On the other hand, degradation of apoE-depleted VLDL was not significantly increased by the presence of lipases even in lovastatin-treated cells. Surface binding of apoE-depleted VLDL to metabolically inactive cells at 4 degrees C was higher in control and HTGL-treated cells, but unchanged in the presence of LPL. Degradation of prebound apoE-depleted VLDL was only 35% as efficient as that of normal VLDL. Surface binding of apoE knockout or apoE-depleted VLDL was to heparin sulfate proteoglycans because it was completely abolished by heparinase treatment. However, apoE appears to be a primary determinant for receptor-mediated VLDL degradation. Our studies suggest that overexpression of LPL or HTGL may not protect against lipoprotein accumulation seen in apoE deficiency.

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.