Abortion after deliberate Arthrotec® addition to food. Mass spectrometric detection of diclofenac, misoprostol acid, and their urinary metabolites.

Arthrotec(®) (AT) is a combination of diclofenac, a nonsteroidal anti-inflammatory drug (NSAID), and misoprostol (MP), a synthetic analogue of prostaglandin E1 (PGE1). MP is a lipophilic methyl ester prodrug. It is readily metabolized to the biologically active misoprostol acid (MPA). During the last few years, medical studies exhibited MP to be an excellent abortive. In this paper, we describe a rare criminal case of MP abortion, initiated by the expectant father. After the abortion, samples of vomit and urine were collected. Systemic exposure to MP is difficult to prove, because both MP and the active metabolite MPA are hardly excreted in urine. Therefore, in addition to routine toxicological analysis, we used slightly modified, well-established liquid and gas chromatographic/tandem mass spectrometric (LC/MS/MS and GC/MS/MS) methods, for the direct and the indirect detection of MPA and its metabolites. In this case, we were able to demonstrate the presence of the major MP metabolites 2,3-dinor-MPA and 2,3,4,5-tetranor-MPA in the urine of the victim. We also detected paracetamol, 3-methoxyparacetamol and diclofenac-glucuronide in the urine. In the vomit of the victim, we detected diclofenac and MPA. These results, combined with the criminal investigations, showed that the accused had mixed MP into the food of his pregnant girlfriend. Finally, these investigations contributed to a confession of the accused.

Lithium reduces aquaporin-2 transcription independent of prostaglandins.

Vasopressin (AVP)-stimulated translocation and transcription of aquaporin-2 (AQP2) water channels in renal principal cells is essential for urine concentration. Twenty percent of patients treated with lithium develop nephrogenic diabetes insipidus (NDI), a disorder in which the kidney is unable to concentrate urine. In vivo and in mouse collecting duct (mpkCCD) cells, lithium treatment coincides with decreased AQP2 abundance and inactivation of glycogen synthase kinase (Gsk) 3ß. This is paralleled in vivo by an increased renal cyclooxygenase 2 (COX-2) expression and urinary prostaglandin PGE(2) excretion. PGE(2) reduces AVP-stimulated water reabsorption, but its precise role in lithium-induced downregulation of AQP2 is unclear. Using mpkCCD cells, we here investigated whether prostaglandins contribute to lithium-induced downregulation of AQP2. In these cells, lithium application reduced AQP2 abundance, which coincided with Gsk3ß inactivation and increased COX-2 expression. Inhibition of COX by indomethacin, leading to reduced PGE(2) and PGF(2α) levels, or dexamethasone-induced downregulation of COX-2 both increased AQP2 abundance, while PGE(2) addition reduced AQP2 abundance. However, lithium did not change the prostaglandin levels, and indomethacin and dexamethasone did not prevent lithium-induced AQP2 downregulation. Further analysis revealed that lithium decreased AQP2 protein abundance, mRNA levels and transcription, while PGE(2) reduced AQP2 abundance by increasing its lysosomal degradation, but not by reducing AQP2 gene transcription. In conclusion, our data reveal that in mpkCCD cells, prostaglandins decrease AQP2 protein stability by increasing its lysosomal degradation, indicating that in vivo paracrine-produced prostaglandins might have a role in lithium-induced NDI via this mechanism. However, lithium affects also AQP2 gene transcription, which is prostaglandin independent.

A randomized comparison of pharmacokinetics of a single vaginal dose of dry misoprostol or misoprostol moistened with normal saline or with acetic acid.

BACKGROUND: The pharmacokinetics of vaginal misoprostol as a dry tablet or as a tablet moistened with normal saline or with acetic acid were studied. METHODS: For this study, 42 women requesting termination of pregnancy at gestational age of <12 weeks were recruited and received 400 µg vaginal misoprostol tablets. They were randomized into three groups: (i) dry tablets, (ii) tablets moistened with 3 ml of normal saline and (iii) tablets moistened with 3 ml of 5% acetic acid. Venous blood samples were taken at 0, 15, 30, 45, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330 and 360 min after misoprostol administration. Misoprostol acid (MPA) was determined in serum samples using gas chromatography/tandem mass spectrometry. RESULTS: The serum peak MPA concentration (C(max)) was significantly higher and the time-to-peak concentration (T(max)) was significantly shorter in the normal saline and acetic acid groups, when compared with the dry tablet group. Both areas under the curve at 240 and 360 min (AUC(240) and AUC(360)) of the normal saline and acetic acid groups were also significantly greater than that of the dry tablet group. The coefficients of variation in C(max) and T(max) were highest in the normal saline group, while that of AUC(240) and AUC(360) were highest in the dry tablet group. The C(max) was significantly higher in subjects in the dry tablet group with vaginal pH < 5 than in those with pH 5. There were no significant differences in other pharmacokinetic parameters between subjects with vaginal pH < 5 and those with vaginal pH 5 in all three groups. CONCLUSIONS: Vaginal misoprostol tablets moistened with normal saline or 5% acetic acid achieved better absorption than the dry tablet. The use of vaginal misoprostol tablets moistened with normal saline or 5% acetic acid would potentially improve the clinical efficacy of misoprostol. HKClinicalTrials.com registration: HKCTR-821.

A Vasopressin-Induced Change in Prostaglandin Receptor Subtype Expression Explains the Differential Effect of PGE2 on AQP2 Expression.

Arginine vasopressin (AVP) stimulates the concentration of renal urine by increasing the principal cell expression of aquaporin-2 (AQP2) water channels. Prostaglandin E2 (PGE2) and prostaglandin2α (PGF2α) increase the water absorption of the principal cell without AVP, but PGE2 decreases it in the presence of AVP. The underlying mechanism of this paradoxical response was investigated here. Mouse cortical collecting duct (mkpCCDc14) cells mimic principal cells as they endogenously express AQP2 in response to AVP. PGE2 increased AQP2 abundance without desmopressin (dDAVP), while in the presence of dDAVP, PGE2, and PGF2α reduced AQP2 abundance. dDAVP increased the cellular PGD2 and PGE2 release and decreased the PGF2α release. MpkCCD cells expressed mRNAs for the receptors of PGE2 (EP1/EP4), PGF2 (FP), and TxB2 (TP). Incubation with dDAVP increased the expression of EP1 and FP but decreased the expression of EP4. In the absence of dDAVP, incubation of mpkCCD cells with an EP4, but not EP1/3, agonist increased AQP2 abundance, and the PGE2-induced increase in AQP2 was blocked with an EP4 antagonist. Moreover, in the presence of dDAVP, an EP1/3, but not EP4, agonist decreased the AQP2 abundance, and the addition of EP1 antagonists prevented the PGE2-mediated downregulation of AQP2. Our study shows that in mpkCCDc14 cells, reduced EP4 receptor and increased EP1/FP receptor expression by dDAVP explains the differential effects of PGE2 and PGF2α on AQP2 abundance with or without dDAVP. As the V2R and EP4 receptor, but not the EP1 and FP receptor, can couple to Gs and stimulate the cyclic adenosine monophosphate (cAMP) pathway, our data support a view that cells can desensitize themselves for receptors activating the same pathway and sensitize themselves for receptors of alternative pathways.

Acyl chain-dependent effect of lysophosphatidylcholine on endothelial prostacyclin production.

Previously we identified palmitoyl-lysophosphatidylcholine (16:0 LPC), linoleoyl-LPC (18:2 LPC), arachidonoyl-LPC (20:4 LPC), and oleoyl-LPC (18:1 LPC) as the most prominent LPC species generated by the action of endothelial lipase (EL) on high-density lipoprotein. In the present study, the impact of those LPC on prostacyclin (PGI(2)) production was examined in vitro in primary human aortic endothelial cells (HAEC) and in vivo in mice. Although 18:2 LPC was inactive, 16:0, 18:1, and 20:4 LPC induced PGI(2) production in HAEC by 1.4-, 3-, and 8.3-fold, respectively. LPC-elicited 6-keto PGF1α formation depended on both cyclooxygenase (COX)-1 and COX-2 and on the activity of cytosolic phospholipase type IVA (cPLA2). The LPC-induced, cPLA2-dependent (14)C-arachidonic acid (AA) release was increased 4.5-fold with 16:0, 2-fold with 18:1, and 2.7-fold with 20:4 LPC, respectively, and related to the ability of LPC to increase cytosolic Ca(2+) concentration. In vivo, LPC increased 6-keto PGF(1α) concentration in mouse plasma with a similar order of potency as found in HAEC. Our results indicate that the tested LPC species are capable of eliciting production of PGI(2), whereby the efficacy and the relative contribution of underlying mechanisms are strongly related to acyl-chain length and degree of saturation.

Cyclooxygenase 2 inhibition exacerbates AQP2 and pAQP2 downregulation independently of V2 receptor abundance in the postobstructed kidney.

Previously we demonstrated that ANG II receptor (AT1R) blockade attenuates V2 receptor (V2R), AQP2, and pS256-AQP2 downregulation in the postobstructed kidney and partially reverses obstruction-induced inhibition of cAMP generation and cyclooxygenase 2 (COX-2) induction. Therefore, we speculated whether the effects of AT1R blockade on V2R and the vasopressin-regulated pathway are attributable to attenuated COX-2 induction. To examine this, rats were subjected to 24-h bilateral ureteral obstruction (BUO) followed by 48-h release and treated with the COX-2 inhibitor parecoxib or saline. Control rats were sham-operated. Parecoxib treatment significantly reduced urine output 24 h after release of BUO whereas urine osmolality and solute-free water reabsorption was comparable between saline- and parecoxib-treated BUO rats. Immunoblotting revealed a significant decrease in AQP2 and pS256-AQP2 abundance to 20 and 23% of sham levels in parecoxib-treated BUO rats compared with 40 and 55% of sham levels in saline-treated BUO rats. Immunohistochemistry confirmed the exacerbated AQP2 and pS256-AQP2 downregulation in parecoxib-treated BUO rats. Finally, parecoxib treatment had no effect on V2R downregulation and the inhibited, vasopressin-stimulated cAMP generation in inner medullary membrane fractions from the postobstructed kidney. In conclusion, COX-2 inhibition exacerbates AQP2 and pS256-AQP2 downregulation 48 h after release of 24-h BUO independently of V2R abundance and vasopressin-stimulated cAMP generation. The results indicate that COX-2 inhibition does not mimic AT1R blockade-mediated effects and that AT1R-mediated AQP2 regulation in the postobstructed kidney collecting duct is independent of COX-2 induction.

Urinary tract obstruction induces transient accumulation of COX-2-derived prostanoids in kidney tissue.

Inhibitors of cyclooxygenase (COX)-2 prevent suppression of aquaporin-2 and reduce polyuria in the acute phase after release of bilateral ureteral obstruction (BUO). We hypothesized that BUO leads to COX-2-mediated local accumulation of prostanoids in inner medulla (IM) tissue. To test this, rats were subjected to BUO and treated with selective COX-1 or COX-2 inhibitors. Tissue was examined at 2, 6, 12, and 24 h after BUO. COX-2 protein abundance increased in IM 12 and 24 h after onset of BUO but did not change in cortex. COX-1 did not change at any time points in any region. A full profile of all five primary prostanoids was obtained by mass spectrometric determination of PGE(2), PGF(2alpha), 6-keto-PGF(1alpha), PGD(2), and thromboxane (Tx) B(2) concentrations in kidney cortex/outer medulla and IM fractions. IM concentration of PGE(2), 6-keto-PGF(1alpha), and PGF(2alpha) was increased at 6 h BUO, and PGE(2) and PGF(2alpha) increased further at 12 h BUO. TxB(2) increased after 12 h BUO. 6-keto-PGF(1alpha) remained significantly increased after 24 h BUO. The COX-2 inhibitor parecoxib lowered IM PGE(2,) TxB(2), 6-keto-PGF(1alpha), and PGF(2alpha) below vehicle-treated BUO and sham rats at 6, 12 and, 24 h BUO. The COX-1 inhibitor SC-560 lowered PGE(2), PGF(2alpha), and PGD(2) in IM compared with untreated 12 h BUO, but levels remained significantly above sham. In cortex tissue, PGE(2) and 6-keto-PGF(1alpha) concentrations were elevated at 6 h only. In conclusion, COX-2 activity contributes to the transient increase in prostacyclin metabolite 6-keto-PGF(1alpha) and TxB(2) concentration in the kidney IM, and COX-2 is the predominant isoform that is responsible for accumulation of PGE(2) and PGF(2alpha) with minor, but significant, contributions from COX-1. PGD(2) synthesis is mediated exclusively by COX-1. In BUO, therapeutic interventions aimed at the COX-prostanoid pathway should target primarily COX-2.

Localization of the succinate receptor in the distal nephron and its signaling in polarized MDCK cells.

When the succinate receptor (SUCNR1) is activated in the afferent arterioles of the glomerulus it increases renin release and induces hypertension. To study its location in other nephron segments and its role in kidney function, we performed immunohistochemical analysis and found that SUCNR1 is located in the luminal membrane of macula densa cells of the juxtaglomerular apparatus in close proximity to renin-producing granular cells, the cortical thick ascending limb, and cortical and inner medullary collecting duct cells. In order to study its signaling, SUCNR1 was stably expressed in Madin-Darby Canine Kidney (MDCK) cells, where it localized to the apical membrane. Activation of the cells by succinate caused Gq and Gi-mediated intracellular calcium mobilization, transient phosphorylation of extracellular regulated kinase (ERK)1/2 and the release of arachidonic acid along with prostaglandins E2 and I2. Signaling was desensitized without receptor internalization but rapidly resensitized upon succinate removal. Immunohistochemical evidence of phosphorylated ERK1/2 was found in cortical collecting duct cells of wild type but not SUCNR1 knockout streptozotocin-induced diabetic mice, indicating in vivo relevance. Since urinary succinate concentrations in health and disease are in the activation range of the SUCNR1, this receptor can sense succinate in the luminal fluid. Our study suggests that changes in the luminal succinate concentration may regulate several aspects of renal function.

Pharmacokinetics of repeated doses of misoprostol.

BACKGROUND: Misoprostol is widely used in obstetrics and gynaecology for medical abortion, cervical priming and induction of labour. To aid the design of effective and safe regimens, we have investigated the pharmacokinetic parameters after the vaginal or sublingual administration of repeated doses of 400 microg of misoprostol. METHODS: Women undergoing termination of pregnancy by suction evacuation were randomized to receive 400 microg of sublingual or vaginal misoprostol every 3 h for five doses. Venous blood was taken at 180, 200, 240, 360, 380, 420, 540, 560, 600, 720, 740, 780 and 900 min after the first dose of misoprostol for determination of the plasma level of misoprostol acid (MPA). RESULTS: The peak plasma levels of MPA decreased with successive doses of vaginal misoprostol, whereas the peak plasma levels were similar with successive doses of sublingual misoprostol. After the third dose, the peak plasma levels of MPA after sublingual misoprostol were significantly higher than those after vaginal administration. After the final dose, the area under the MPA concentration-time curve after sublingual administration was significantly higher than that after vaginal misoprostol (P < 0.031). However, subgroup analysis in the vaginal administration group showed that the progressive decline in the peak plasma levels of MPA occurred only in women with significant vaginal bleeding. CONCLUSIONS: The peak plasma level of MPA after each dose of misoprostol is higher and the bioavailability is also greater after sublingual administration, compared with that after vaginal administration, of repeated doses of misoprostol. The difference was probably due to the reduction in absorption of vaginal misoprostol in the presence of significant vaginal bleeding.

Parecoxib does not suppress thromboxane synthesis in newborn piglets with group B streptococcal sepsis.

Group B streptococci (GBS) cause fatal sepsis in newborns. Strong activation of thromboxane synthesis is assumed to correlate with severe pulmonary hypertension. In this study we compared the impact of indomethacin versus parecoxib on hemodynamics and outcome and investigated the pharmacological effects on thromboxane synthesis and EP-3 receptor gene expression. Whereas both parecoxib and indometacin reduced expression of thromboxane synthase and EP-3 receptor in infected lung tissue, parecoxib did not suppress urine levels of thromboxane like indometacin. We presume that COX-2 inhibition in GBS sepsis is associated with enhanced thrombogenicity.

Adaptation of the hypothalamic blood flow to chronic nitric oxide deficiency is independent of vasodilator prostanoids.

The aim of our study was to investigate the adaptation of the hypothalamic circulation to chronic nitric oxide (NO) deficiency in rats. Hypothalamic blood flow (HBF) remained unaltered during chronic oral administration of the NO synthase (NOS) inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME, 1 mg/ml drinking water) although acute NOS blockade by intravenous l-NAME injection (50 mg/kg) induced a dramatic HBF decrease. In chronically NOS blocked animals, however, acute l-NAME administration failed to influence the HBF. Reversal of chronic NOS blockade by intravenous l-arginine infusion evoked significant hypothalamic hyperemia suggesting the appearance of a compensatory vasodilator mechanism in the absence of NO. In order to clarify the potential involvement of vasodilator prostanoids in this adaptation, cyclooxygenase (COX) mRNA and protein levels were determined in the hypothalamus, but none of the known isoenzymes (COX-1, COX-2, COX-3) showed upregulation after chronic NOS blockade. Furthermore, levels of vasodilator prostanoid (PGI(2), PGE(2) and PGD(2)) metabolites were also not elevated. Interestingly, however, hypothalamic levels of vasoconstrictor prostanoids (TXA(2) and PGF(2alpha)) decreased after chronic NOS blockade. COX inhibition by indomethacin but not by diclofenac decreased the HBF in control animals. However, neither indomethacin nor diclofenac induced an altered HBF-response after chronic l-NAME treatment. Although urinary excretion of PGI(2) and PGE(2) metabolites markedly increased during chronic NOS blockade, indicating COX activation in the systemic circulation, we conclude that the adaptation of the hypothalamic circulation to the reduction of NO synthesis is independent of vasodilator prostanoids. Reduced release of vasoconstrictor prostanoids, however, may contribute to the normalization of HBF after chronic loss of NO.

Specific components of prostanoid-signaling pathways are present in non-small cell lung cancer cells.

In the present study, we measured prostanoid synthesis and the expression of genes associated with prostanoid signaling in human non-small cell lung carcinoma (NSCLC) cell lines and in primary human tumors. Consistent with the proposed growth promoting role of PGE2, we found that NSCLC cell lines frequently co-expressed the genes encoding cyclooxygenase-2 and the prostaglandin E2 (PGE2) receptors EP1, 2 and 4 concomitant with the synthesis of PGE2. In contrast, NSCLC cells did not synthesize appreciable amounts of prostaglandin I2 (PGI2, prostacyclin), lacked PGI2 synthase (PGIS) and did not express the gene coding for the PGI2 receptor IP at detectable levels. In agreement with this finding, PGIS mRNA levels were dramatically diminished in primary human tumor samples as compared to matched normal lung tissue. Finally, thromboxane A2 (TxA2) was synthesized in NSCLC cell lines, but transcription of the gene coding for the TxA2 receptor TP was not observed in these cells. In marked contrast, lung fibroblasts synthesized all three prostanoids and their receptors at high levels. While the observed expression patterns were consistent with the existence of autocrine/paracrine PGE2 signaling loops in NSCLC cells, PGI2- and TxA2-mediated signals may play a role in tumor stroma cells.

Induction of PPARbeta and prostacyclin (PGI2) synthesis by Raf signaling: failure of PGI2 to activate PPARbeta.

A role for the nuclear receptor peroxisome proliferator-activated receptor-beta (PPARbeta) in oncogenesis has been suggested by a number of observations but its precise role remains elusive. Prostaglandin I2 (PGI2, prostacyclin), a major arachidonic acid (AA) derived cyclooxygenase (Cox) product, has been proposed as a PPARbeta agonist. Here, we show that the 4-hydroxytamoxifen (4-OHT) mediated activation of a C-Raf-estrogen receptor fusion protein leads to the induction of both the PPARbeta and Cox-2 genes, concomitant with a dramatic increase in PGI2 synthesis. Surprisingly, however, 4-OHT failed to activate PPARbeta transcriptional activity, indicating that PGI2 is insufficient for PPARbeta activation. In agreement with this conclusion, the overexpression of ectopic Cox-2 and PGI2 synthase (PGIS) resulted in massive PGI2 synthesis but did not activate the transcriptional activity of PPARbeta. Conversely, inhibition of PGIS blocked PGI2 synthesis but did not affect the AA mediated activation of PPARbeta. Our data obtained with four different cell types and different experimental strategies do not support the prevailing opinion that PGI2 plays a significant role in the regulation of PPARbeta.

Delayed in vivo catabolism of intermediate-density lipoprotein and low-density lipoprotein in hemodialysis patients as potential cause of premature atherosclerosis.

OBJECTIVE: Premature cardiovascular disease is the leading cause of death in patients with end-stage renal disease treated by hemodialysis (HD). Low-density lipoprotein (LDL) levels are not generally increased in HD patients, but their LDL metabolism is still poorly understood. We therefore investigated the in vivo metabolism of apoB-containing lipoproteins in two different ethnic populations of HD patients and controls. METHODS AND RESULTS: We performed stable isotope kinetic studies using a primed constant infusion of deuterated leucine in 12 HD patients and 13 healthy controls. Tracer/tracee ratio of apoB was determined by means of gas chromatography/mass spectrometry, and the modeling program SAAMII was used to estimate the fractional catabolic rate (FCR) of apoB. Mean LDL-apoB plasma concentrations were almost identical in both groups (HD: 95+/-30 mg/dL, controls: 91+/-40 mg/dL), whereas LDL-apoB FCR was 50% lower in HD patients as compared with controls (0.22+/-0.12 days(-1) versus 0.46+/-0.20 days(-1), P=0.001) with concomitantly decreased production rates of LDL. Compared with controls, intermediate-density lipoprotein (IDL)-apoB FCR was 65% lower (2.87+/-1.02 days(-1) versus 8.89+/-4.94 days(-1), P=0.014), accompanied by 1.5-fold higher IDL-apoB levels in HD. Very low-density lipoprotein metabolism was similar in both study groups. CONCLUSIONS: In vivo catabolism of LDL and IDL is severely impaired in HD patients but misleadingly masked by normal plasma cholesterol levels. The resulting markedly prolonged residence times of both IDL and LDL particles might thus significantly contribute to the well-documented high risk for premature cardiovascular disease in HD patients.

Effects of celecoxib and diclofenac on blood pressure, renal function, and vasoactive prostanoids in young and elderly subjects.

Cyclooxygenase (COX) inhibitors are among the most widely used drugs, especially in the elderly. It has been claimed that the new COX-2 inhibitors offer advantages in terms of drug safety. To test this hypothesis, the authors compared in a double-blind, randomized trial the effects of celecoxib (200 mg bid) and diclofenac (75 mg bid) on blood pressure and renal function in two groups (each n = 12) of young (mean age = 32 years) and elderly (mean age = 68 years) normotensive subjects. Changes from baseline in the 24-hour blood pressure profiles, parameters of the renin-angiotensin-aldosterone system, inulin clearance, urinary marker proteins, and eicosanoid excretion were monitored during the treatment period of 2 weeks. Comparison between celecoxib and diclofenac showed no significant difference in minor alterations of blood pressure. During daytime, there was a trend to elevation of mean arterial blood pressure (mmHg) by celecoxib in the elderly of 2.8 (95 % confidence interval [CI) = -2.5 to 8.2) in comparison with the young subjects of -1.3 (95% CI= -3.7 to 1.0); there was also a trend to elevation of mean arterial blood pressure by diclofenac in the elderly of 4.1 (95% CI= -1.2 to 9.4) in comparison with the young subjects of 0.4 (95% CI= -2.4 to 3.2). In both populations, the authors found no significant drug effects on the parameters of the renin-angiotensin-aldosterone system, inulin clearance, and urinary marker proteins. As expected, diclofenac reduced excretion of allprostanoids, whereas celecoxib did not affect production of TxB2 and its metabolites. Neither in young nor in elderly normotensive subjects were blood pressure and renal function significantly affected by a short-term treatment with standard doses of celecoxib and diclofenac. Therefore, normal aging appears not to represent a special risk factor in therapy with these two agents.

Determination of misoprostol free acid in human breast milk and serum by gas chromatography/negative ion chemical ionization tandem mass spectrometry.

To study an expected transition of misoprostol from human blood into breast milk, a novel method for the determination of its active metabolite misoprostol acid (MPA) was developed. MPA was determined in serum and breast milk samples by an isotope dilution assay using gas chromatography/negative ion chemical ionization tandem mass spectrometry (GC/NICI-MS/MS). After addition of (15S)-15-methylprostaglandin E(2) (15-methyl-PGE(2)) as an internal standard, MPA was extracted from both matrices using a reversed-phase cartridge. The prostanoids were derivatized with O-2,3,4,5,6-pentafluorobenzylhydroxylamine hydrochloride (PFBHA) and 2,3,4,5,6-pentafluorobenzyl bromide (PFBB) to the pentafluorobenzyl oxime (PFBO)-pentafluorobenzyl ester (PFB) derivatives. The sample was subjected to thin-layer chromatography with ethyl acetate-hexane (1 : 1 (v/v)) as the developing solvent. The corresponding zone was extracted. After derivatization to the trimethylsilyl ether, MPA was determined by GC/NICI-MS/MS using the [molecule (M) - pentafluorobenzyl (PFB)](-) ([P](-)) ions as precursor in the negative ion chemical ionization mode. The product ions used for quantification were [P - 2TMSOH - C(6)F(5)CH(2)OH](-) (MPA) and [P - 2TMSOH - C(6)F(5)CH(2)OH - CO(2)](-)(15-methyl-PGE(2)), respectively. The limit of quantification for MPA was approximately 1 pg ml(-1) in breast milk and serum samples. The correlation coefficients of the calibration curves for MPA were r > 0.997 in the 0.5-2000 pg ml(-1) range for both tested matrices.

Analysis of the labial gland secretions of the male bumblebee Bombus griseocollis (Hymenoptera: Apidae).

The labial gland secretions from males of the bumblebee Bombus (Separatobombus) griseocollis De Geer, a bumblebee exhibiting perching behaviour, were analysed by gas chromatography/mass spectrometry (GC/MS) in the electron impact and positive ion chemical ionization mode. The major compound of the complex mixture of alkenols, acetates, hydrocarbons, wax type esters and steroids is tetradecyl acetate, considerable amounts of hexadecyl, geranyllinaloyl, geranylgeranyl, docosyl, tetracosenyl and hexacosenyl acetate were also found. 1,3-Tetradecanediol diacetate, detected as a minor component, has not yet been identified in male bumblebee labial gland secretions. Besides small amounts of primary alcohols (tetradecanol and hexadecanol) the tertiary alcohol geranyllinalool (3,7,11,15-tetramethyl-hexadeca-1,6,10,14-tetraene-3-ol) was also present. The primary alcohols were also present as esters of butanoic, dodecanoic, tetradecanoic, and hexadecanoic acid. Besides the usual mixture of un- and mono-unsaturated straight chain hydrocarbons, the labial gland contains the isoprenoid hydrocarbons beta-springene [(6E, 10E)-7,11,15-trimethyl-3-methylene-hexadeca-1,6,10,14-tetraene] and two isomers of a-springene [(3Z,6E,10E)- and (3E,6E,10E)-3,7,11,15-tetramethyl-hexadeca-1,3,6,10,14-pentaene]. The close relationship in chemical composition in male bumblebees with perching and flight pass behaviour is discussed.

Analysis of the labial gland secretions of the male bumble bee Bombus perplexus Cresson (Hymenoptera: Apidae) from North America.

The labial gland secretions from males of the bumble bee Bombus (Pyrobombus) perplexus Cresson were analysed by gas chromatography/mass spectrometry (GC/MS) in the electron impact and positive ion chemical ionization mode. The major compound of the complex mixture of alkenols, alkenals, fatty acids, hydrocarbons, wax type esters and steroids is 3,7,11,15-tetramethyl-2,6,10-hexadecatrien-1-ol (geranylcitronellol), considerable amounts of hexadecan-1-ol and Z-9-hexadecen-1-ol were also found. All alcohols were present as esters of the detected acids. In older samples both the acids and the alcohols sometimes could not be detected in the GC; therefore, the possibility to check the detected acid-alcohol pattern by interpreting the wax type ester peaks is very instructive. Moreover, the labial gland contains a rich mixture of mono- and di-unsaturated straight chain hydrocarbons. The similarity in composition of the labial glands of the North American B. (Pyrobombus) perplexus with the Eurasian species B. (Pyrobombus) hypnorum corroborates the assumption that the two species are conspecific. The likely supposition that the hydrocarbons could play an essential role in the chemical communication in bumble bees is discussed.

In vivo stable-isotope kinetic study suggests intracellular assembly of lipoprotein(a).

OBJECTIVE: Lipoprotein(a) [Lp(a)] consists of apolipoprotein B-100 (apoB-100) as part of an LDL-like particle and the covalently linked glycoprotein apolipoprotein(a) [apo(a)]. Detailed mechanisms of its biosynthesis, assembly, secretion and catabolism are still poorly understood. To address the Lp(a) assembly mechanism, we studied the in vivo kinetics of apo(a) and apoB-100 from Lp(a) and LDL apoB-100 in nine healthy probands using stable-isotope methodology. METHODS: The level of isotope enrichment was used to calculate the fractional synthesis rate (FSR), production rate (PR) and retention time (RT) using SAAMII software and multicompartmental modeling. RESULTS: We observed a similar mean PR for apo(a) (1.15 nmol/kg/d) and apoB-100 (1.31 nmol/kg/d) from Lp(a), which differed significantly from the PR for apoB-100 from LDL (32.6 nmol/kg/d). Accordingly, mean FSR and RT values for Lp(a)-apo(a) were similar to those of Lp(a)-apoB and different from those for LDL-apoB. CONCLUSION: Two different kinetic apoB pools within Lp(a) and LDL suggest intracellular Lp(a) assembly from apo(a) and newly synthesized LDL.

Genetics and kinetics of familial hypercholesterolemia, with the special focus on FH-(Marburg) p.W556R.

OBJECTIVE: Familial hypercholesterolemia (FH) is an autosomal dominant inherited disorder, caused by mutations in the low density lipoprotein receptor (LDLR) gene. FH is characterized by elevated plasma LDL cholesterol, premature atherosclerosis and high risk of premature myocardial infarction. Extended work has been done to understand both, the primary genetic defect as well as the in vivo kinetic consequences of this disease. Both approaches, genetics and kinetics, are challenging but also fruitful approaches for a better understanding of this devastating disease. For this we reviewed the recent literature and used our in vitro and in vivo data on one of the most frequently occurring types of FH, the FH(Marburg) p.W556R. METHODS: To identify the primary genetic defect of the FH(Marburg) we used denaturing gradient gel electrophoresis (DGGE) mutation analysis. In vivo kinetic studies were performed in a heterozygote FH(Marburg) subject and in 5 healthy control subjects utilizing a stable isotope tracer kinetic approach with 3D-leucine. RESULTS: DGGE screening of the LDLR gene identified a tryptophan (W) to arginine (R) substitution at residue 556 (p.W556R) in the fifth conserved YWTD repeat of the LDLR-beta-propeller in FH(Marburg). In vivo kinetic studies in a heterozygote FH subject for FH(Marburg) and in 5 healthy control subjects demonstrated a severe decrease in LDL FCR and a mild increase of LDL PR in FH compared to healthy controls. CONCLUSIONS: The LDLR mutation p.W556R is a frequent and severe defect for FH. This defect has a major influence on the in vivo lipoprotein kinetics and lipid levels. In a heterozygote FH patient we found a dual defect for the increase in LDL cholesterol, namely a decrease in the fractional catabolic rate (FCR) of LDL but also an increase in LDL production rate (PR). By this a well defined, single genetic defect may have a series of different in vivo metabolic consequences which could be used for potential therapeutic approaches to this disease.