Evidence for cometabolic transformation of weathered toxaphene under aerobic conditions using camphor as a co-substrate.

AIMS: Toxaphene is a persistent organic pollutant, composed of approximately 1000 highly chlorinated bicyclic terpenes. The purpose of this study was to evaluate if camphor, a structural analogue of toxaphene, could stimulate aerobic biotransformation of weathered toxaphene. METHODS AND RESULTS: Two enrichment cultures that degrade camphor as the sole carbon source were established from contaminated soil and biosolids. These cultures were used to evaluate aerobic transformation of weathered toxaphene. Only the biosolids culture could transform compounds of technical toxaphene (CTTs) in the presence of camphor, while no transformation was observed in the presence of glucose or with toxaphene as a sole carbon source. The transformed toxaphene had lower concentration of CTTs with longer retention times, and higher concentration of compounds with lower retention times. Gas chromatography with electron capture negative ion mass spectrometry (GC/ECNI-MS) showed that aerobic biotransformation mainly occurred with Cl8 - and Cl9 -CTTs compounds. The patterns of Cl6 - and Cl7 -CTTs were also simplified albeit to a much lesser extent. Seven camphor-degrading bacteria were isolated from the enrichment culture but none of them could degrade toxaphene. CONCLUSION: Camphor degrading culture can aerobically transform CCTs via reductive pathway probably by co-metabolism using camphor as a co-substrate. SIGNIFICANCE AND IMPACT OF THE STUDY: Since camphor is naturally produced by different plants, this study suggests that stimulation of aerobic transformation of toxaphene may occur in nature. Moreover plants, which produce camphor or similar compounds, might be used in bioremediation of contaminated soils.

Halogenated Natural Products in Dolphins: Brain-Blubber Distribution and Comparison with Halogenated Flame Retardants.

Halogenated natural products (MHC-1, TriBHD, TetraBHD, MeO-PBDEs, Q1, and related PMBPs) and halogenated flame retardants (PBDEs, HBB, Dec 602, Dec 603, and DP) in blubber and brain are reported from five Alboran Sea delphinids (Spain). Both HNPs and HFRs were detected in brain, implying that they are able to surpass the blood-brain barrier and reach the brain, which represents a new finding for some compounds, such as Q1 and PMBPs, MHC-1, TriBHD, TetraBHD, or Dec 603. Moreover, some compounds (TetraBHD, BDE-153, or HBB) presented higher levels in brain than in blubber. This study evidence the high concentrations of HNPs in the marine environment, especially in top predators. It shows the importance of further monitoring these natural compounds and evaluating their potential toxicity, when most studies focus on anthropogenic compounds only. While no bioaccumulation was found for ∑HNPs, ∑HFRs increased significantly with body size for both common and striped dolphins. Studies evaluating BBB permeation mechanisms of these compounds together with their potential neurotoxic effects in dolphins are recommended.

Chlorinated paraffins (CPs) in salmon sold in southern Germany: Concentrations, homologue patterns and relation to other persistent organic pollutants.

Chlorinated paraffins (CPs) are complex mixtures of persistent contaminants present throughout the aquatic food web. In this study 122 farmed and 11 wild salmon samples were collected over the course of four years (2014-2017). The ratio of short-chain CP and medium-chain CP and the corresponding homologue patterns were determined by means of gas chromatography (GC) with high resolution, accurate mass Orbitrap mass spectrometry (MS) technology. Characteristic patterns were observed, enabling differentiation between European and non-European (Chilean) samples. Concentration ranges of short-chain CPs (0.97-170 ng/g ww) and medium-chain CPs (1.1-79 ng/g ww) were similarly widespread over three orders of magnitude. Yet, both the mean and median concentrations of MCCPs were usually higher than those of the SCCP. CP levels were generally higher than those of marker polychlorinated biphenyls (PCBs) and hexabromocyclododecanes (HBCDDs). An age- and gender-dependent estimated intake range of 4.6-35 ng/kg bw/week for short and medium-chain CPs via the consumption of salmon was calculated for adults in Germany.

Persistent organohalogen contaminant burdens in Antarctic krill (Euphausia superba) from the eastern Antarctic sector: a baseline study.

A baseline for persistent organohalogen compound (POC) accumulation in the Antarctic keystone species, Antarctic krill (Euphausia superba) has been established for a 50 degrees longitudinal range of the eastern Antarctic sector. Samples of adult krill, caught from 12 sites distributed between 30 degrees and 80 degrees E (60-70 degrees S), were analysed for >100 organohalogen compounds including chlorinated pesticides, polychlorinated biphenyls (PCBs), polybrominated organic compounds and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs). Organochlorine pesticides dominated measured krill contaminant burdens with hexachlorobenzene (HCB) as the single most abundant compound quantified. Krill HCB concentrations were comparable to those detected at this trophic level in both the Arctic and temperate northwest Atlantic, lending support for the hypothesis that HCB will approach global equilibrium at a faster rate than other POCs. Para, para'-dichlorodiphenylethene (p,p'-DDE) was detected at notable concentrations. Measurements of DDT and its degradation products provide an important baseline for monitoring the temporal and geographical influence of renewed, DDT usage for malaria-control in affected southern hemisphere countries. In contrast to the Arctic, PCBs did not feature prominently in contaminant burdens of Antarctic krill. The major commercial polybrominated diphenyl ether (PBDE) congeners -99 and -47 were quantified at low background levels with clear concentration spikes observed at around 70 degrees E , in the vicinity of modern, active research stations. The likelihood that local anthropogenic activities are supplementing low PBDE levels, delivered otherwise primarily via long range environmental transport, is discussed. The suspected naturally occurring brominated organic compound, 2,4,6-tribromoanisole (TBA), was a ubiquitous contaminant in all samples whereas the only PCDD/Fs quantifiable were trace levels of octachlorodibenzo-p-dioxin (OCDD) and 1,2,3,4,7,8/1,2,3,4,7,9-hexachlorodibenzofuran (HxCDF). With the aims of; i) Generating a robust and broadly applicable POC auditing platform for the scarcely studied eastern Antarctic sector; ii) Determining the compounds accumulating in Antarctic krill for further toxicity evaluation studies and iii) Establishing a baseline for Antarctic predator exposure to POCs, this study represents one of the most comprehensive reports of POC contamination of the Antarctic food web to date.

Occurrence of halogenated natural products in highly consumed fish from polluted and unpolluted tropical bays in SE Brazil.

Natural compounds from the metabolism of marine organisms have been detected at high concentrations in environmental samples which are not the producers of these compounds. These natural substances are known as halogenated natural products (HNPs). HNPs are possibly toxic halogenated compounds analogous to POPs that may bioaccumulate and biomagnify along the food web and pose a further risk to human and environmental health. The present study analyzed the occurrence of HNPs in the edible muscle of the three most consumed commercial fish species in the state of Rio de Janeiro: sardine (Sardinella brasiliensis), whitemouth croaker (Micropogonias furnieri) and mullet (Mugil liza) from the highly polluted Guanabara Bay (GB) and the less polluted Ilha Grande Bay (IGB). The analytical steps included Soxhlet extraction, clean-up step and injection in a gas chromatography system coupled to a mass spectrometer operated in the electron-capture negative ion mode (GC/ECNI-MS). The compounds 2,4,6-TBP, 2,4,6-TBA, MHC-1, Q1, 6-MeO-BDE 47 and 2'-MeO-BDE 68 were found in the analyzed fish from both studied areas. Q1, 6-MeO-BDE 47 and 2'-MeO-BDE 68 showed the highest concentrations in samples. Q1 concentrations in the sardines from IGB were higher than the sardines from GB (p < 0.05) and higher than the other IGB species (p < 0.05). The differences found among the species may be related to their characteristic habitat and diet. It is noteworthy that most of these compounds do not have any toxicological reference value. Moreover, the HNPs are being detected in species of low trophic level and since this study has worked only with commercial species, these fish may be considered as a source for human exposure to these natural compounds.

Interactions between 8-L-arginine vasopressin and prostaglandin E2 in human mononuclear phagocytes.

The effect of 8-L-arginine vasopressin (AVP) on biosynthesis of prostaglandins in human mononuclear phagocytes was examined. AVP, oxytocin, and deamino-(8-D-arginine) vasopressin (dDAVP) affected prostaglandin biosynthesis in a rank order that parallels their pressor but not antidiuretic activity (AVP greater than oxytocin greater than dDAVP). Radioimmunoassay, incorporation studies using [14C]arachidonic acid and radiometric thin-layer chromatography, revealed prostaglandin E2 (PGE2) to be the only prostaglandin synthesized by the mononuclear phagocytes. While high concentrations of PGE2 elevated cytoplasmic levels of cyclic AMP by five- to sevenfold above basal values, low concentrations of PGE2 that are released by the cells in the presence of AVP failed to increase cyclic AMP content in the cells. However, PGE2 at concentrations that do not alter cyclic AMP levels markedly interferes with the activity of AVP. This effect is, however, very time dependent. Addition of PGE2 to the cells 30 min before AVP, was followed by a period of unresponsiveness to the hormone that lasts at least 30 min. Pretreatment of the cells with indomethacin enhanced the AVP-mediated accumulation of intracellular cyclic AMP level. PGE2 did not modify [3H]AVP binding, indicating that its inhibitory effect on the activity of the peptide is not due to downregulation of vasopressin receptors.

125I-8-L-arginine vasopressin binding to human mononuclear phagocytes.

The binding of vasopressin to human circulating blood cells was examined. Direct binding studies with preparations of single cell types indicated that the mononuclear phagocyte system is almost entirely responsible for binding of the hormone. Binding of 125I-8-L-arginine vasopressin (AVP) (40 pM) in the presence of excess unlabeled hormone was saturable (2.8 +/- 0.4 fmol/2 x 10(6) cells per ml), was linear with cell number, was dependent upon the concentration of the radioligand used, and was reversible. Binding equilibrium was achieved in 30--40 min at 22 degrees C. Scatchard analysis of binding at this time showed an apparent dissociation constant of 25 +/- 0.21 pM, providing an estimate of 640 +/- 80 sites/cell. Pretreatment of the cells with cytochalasin B, an agent that can block phagocytosis, did not modify radioligand binding, which indicates that 125I-AVP uptake by the cells is due to binding and not to endocytosis. Specificity of vasopressin-sensitive sites on mononuclear phagocytes was demonstrated with a series of vasopressin analogues with various degrees of antidiuretic potency, and with peptide hormones that bind to specific receptors on circulating blood cells but that lack antidiuretic activity. AVP (40 pM) elevated the intracellular level of cyclic AMP from 137 +/- 8.6 to 350 +/- 20.5 pmol/mg cell protein. The binding affinities of the various analogues were correlated with their ability to stimulate intracellular cyclic AMP synthesis (Lys8-vasopressin less than deamino(8-D-Arg)-vasopressin less than oxytocin).

TNF-alpha -308G>A polymorphism modulates cytokine serum concentrations and macrovascular complications in diabetic patients on aspirin.

BACKGROUND: Tumor necrosis factor (TNF)-alpha has pleiotropic effects in cytokine-mediated inflammation underlying atherogenesis. Activation of this inflammatory process is assumed to be different in diabetic and non-diabetic individuals. Previous studies in non-diabetic subjects showed no association between TNF-alpha -308G>A polymorphism and coronary artery disease. METHODS: Vascular complications and cytokine serum concentrations were assessed as a function of the TNF-alpha -308G>A polymorphism in 76 diabetic patients on low-dose aspirin. RESULTS: Of 76 adult diabetic patients, 18 (24%) carried the TNF-alpha -308A allele (17 AG, 1 AA) and 58 (76%) carried wild-type alleles (GG). Prevalence of macrovascular complications was 33% in TNF-alpha -308A allele carriers (AG+AA) and 78% in wild-type allele carriers (GG) (p<0.001). In contrast, prevalence of microvascular complications was 78% and 84%, respectively, and did not significantly differ between the study groups. TNF-alpha -308A allele carriers (AG+AA) compared to wild-type allele carriers (GG) had significantly lower median serum concentrations of hs-C-reactive protein (1.5 vs 2.9 mg/L, p=0.030), interleukin 1-beta (0.9 vs 1.2 ng/L, p=0.046), and interleukin-6 (3.6 vs 4.9 ng/L, p=0.023). In multiple regression analysis, the prevalence of macrovascular diabetic complications was significantly associated with TNF-alpha -308G>A polymorphism (p<0.001) and serum concentrations of HDL-cholesterol (p=0.007) while confounding effects of further variables were excluded. CONCLUSION: TNF-alpha -308G>A polymorphism modulates cytokine serum concentrations and macrovascular complications in diabetic patients on aspirin. Diabetic carriers of the TNF-alpha -308A allele might benefit more from a prophylaxis with low dose aspirin than non-carriers.

Patient education in asthma: a survey of physicians' knowledge of the principles and implementation of self management in practice.

BACKGROUND: Therapeutic patient education, particularly when including written instructions in self-management, improves outcomes in asthma. The education of patients in self-management requires specific knowledge and skills, which are not generally taught in under- or postgraduate training programmes. PURPOSE: To investigate physicians' knowledge of the principles and implementation of self-management in asthma care. METHOD: A 14-item questionnaire was developed, piloted and subsequently sent to 1039 general physicians (general practitioners and internists) and pulmonologists registered as members of the Medical Society of Zurich. RESULTS: 368 (35%) of the physicians returned the questionnaire. 352 (96%) stated that they care for patients with asthma, 312 (87%) provided asthma education, 264 (75%) gave information about the mechanisms of illness, 272 (77%) provided instructions on how to use inhalers although only 212 (60%) checked inhaler technique. 170 (48%) instructed patients in home measurement of peak flow recordings (PEFR). 21% of general physicians and 52% of pulmonologists provided written action plans outlining what actions to take if PEFR or symptoms deteriorated. The majority of physicians were aware of positive benefits of patient education and over 80% stated that all asthmatic patients should be offered education. Only 32% felt that they should personally be educating the patients whilst two-thirds expressed a preference for the education to be provided by a specialist centre. 66% of the physicians expressed a desire to undertake further training in effective patient education. CONCLUSION: Whilst most physicians in this study state to be aware of the benefits of patient education in asthma, only 24% actually provide their patients with asthma self-management plans. With a low response rate, our study is likely to be biased towards those physicians with a greater interest in asthma; hence actual use of self-management plans is likely be lower than in our sample.

Fish oil affects phosphoinositide turnover and thromboxane A metabolism in cultured vascular muscle cells.

Fish oil has been reported as having beneficial effects on cardiovascular diseases. Elevated serum lipoproteins, prostaglandins and intracellular free calcium concentrations [( Ca2+]i) of the vasculature and thus the phosphoinositide (PI) turnover may be involved in the pathogenesis of these disorders. Therefore, the effect of fish oil on the potency of both low-density lipoprotein (LDL) and angiotensin II (AII) to stimulate the PI turnover in cultured rat vascular smooth muscle cells (VSMC) has been studied. Furthermore, a possible link between PI turnover activity and thromboxane A2 (TXA2) metabolism in these cells has been investigated. In VSMC cultured for up to 7 weeks with either fish oil or n-3 eicosapentaenoic acid (EPA) a decrease to 5-48% of the LDL-induced inositol trisphosphate (IP3) formation (= 100%) was found. A similar range of decreased IP3 synthesis was observed, when AII was used instead of LDL. Both LDL- and AII-stimulated TXA2 synthesis was suppressed concomitantly within the range 34-60%. Blockade of VSMC TXA2 biosynthesis with either indomethacin or TXA2 synthetase blocker (SQ-80338) inhibited LDL-induced formation of IP3 in a dose-dependent manner. Similar results were obtained, when TXA2 receptor coupling antagonists (SQ-27427 or BM-13177) were used. However, blockers of TXA2 synthesis and of TXA2 receptor binding failed to affect AII-induced formation of IP3.

Brominated flame retardants and other organobromines in Norwegian predatory bird eggs.

A set of 62 unhatched eggs was collected from six different predatory bird species throughout Norway after incubation period was completed. They were analysed for PBDE, PBB, TBBP A and naturally occurring halogenated compounds. BDE 47, 99 and 153 were the dominating congeners, with species dependent PBDE patterns. BDE 153 was observed as the most abundant congener in eggs of peregrine falcon, golden eagle and merlin. The highest PBDE level (sum of nine congeners) was found in eggs of white-tailed sea eagle with up to 800ng/gww (median sumPBDE: 184ng/gww), followed by eggs of peregrine falcon and osprey (median sumPBDE: 155 and 105ng/gww, respectively). Golden eagle eggs showed the lowest concentration of all species (median sumPBDE: 3ng/gww). The levels in the peregrine falcon are similar to those found earlier in the Baltic region [Lindberg, P., Sellstrom, U., Haggberg, L., de Wit, C.A., 2004. Higher brominated diphenyl ethers and hexabromocyclododecane found in eggs of peregrine falcons (Falco peregrinus) breeding in Sweden. Environmental Science & Technology. 38 (1), 93-96]. The differences between species are not fully explainable, due to lack of data from the major food species. BB 101 and 153 were found in eggs of all investigated bird species. Especially in samples of white-tailed sea eagle, peregrine falcon and goshawk additional unknown penta- and hexabrominated biphenyls were detected. TBBP A was detected in all of eight eggs analysed sampled from four different bird of prey species. The naturally occurring halogenated compounds Q1, the dibromotrichloro monoterpene MHC-1, and 2,4,6-tribromoanisole (TBA) were detected in all of seven analysed samples except for one peregrine falcon egg.

Twenty-four-hour secretory pattern of cortisol in the bull: evidence of episodic secretion and circadian rhythm.

A single antibody RIA method for measurement of plasma cortisol concentrations in the bull is described. Antisera were obtained from rabbits immunized against cortisol-3-oxime-bovine serum albumin. By this technique, peripheral cortisol levels were determined in seven adult bulls (one blind) during 24- and 48-h periods, with blood collections every 30 min. Statistical evaluation of the 24-h profiles using time series analysis revealed that cortisol is secreted episodically throughout the day-night cycle (range, 0.4-9.7 ng/ml). Despite individual variability in both frequency and amplitude of secretory episodes, a distinct circadian secretion pattern was recognized. After dividing the 24 h into three 8-h time periods (I, 0900-1700 h; II, 1700-0100 h; III, 0100-0900 h), a depressed secretory activity with small episodic bursts not exceeding 3.5 ng/ml plasma consistently occurred during time period II. Increased cortisol secretion with high fluctuating levels was evident during time periods I and III. Maximum cortisol concentrations greater than 8 ng/ml were noticed in the morning at the onset of daylight, whereas lowest values were recorded in the evening when darkness began. Results from this study indicate that there is a temporal correlation between the rhythm of cortisol secretion and the light-dark cycle in the bovine species.

Novel cellular activities for low density lipoprotein in vascular smooth muscle cells.

Hyperlipidemia and hypertension play important roles in the pathogenesis of atherosclerosis. To investigate the underlying intracellular mechanisms, we studied the effect of various concentrations of low density lipoprotein from normolipidemic subjects on concentrations of free intracellular calcium, intracellular pH, DNA synthesis, and vascular tone in vascular smooth muscle cells and rings from rat aortas. Low density lipoprotein in the range of 1-15 micrograms/ml induced a dose-dependent increase of concentration of free intracellular calcium and a biphasic change of the intracellular pH. Similar concentrations of low density lipoprotein led to an enhanced DNA synthesis. Furthermore, cumulative addition of 1-15 micrograms/ml low density lipoprotein produced a dose-dependent increase in contractile tension of thoracic aortic rings from rats. The maximal low density lipoprotein-induced contractile response was approximately 70% of that induced by 40 mM KCl. These findings indicate that low concentrations of low density lipoprotein occurring, for example, in the extravascular fluid might contribute to the pathogenesis of cardiovascular diseases by enhancing cell proliferation and vasoconstriction by changing intracellular calcium and intracellular pH.

The platelet-derived growth factor isomers, PDGF-AA, PDGF-AB and PDGF-BB, induce contraction of vascular smooth muscle cells by different intracellular mechanisms.

The effect of human recombinant platelet-derived growth factor (PDGF) isoforms, (r)PDGF-AA, PDGF-AB and PDGF-BB, on contractility of rat aortic rings as well as on intracellular free Ca2+ ([Ca2+]i), intracellular pHi (pHi) and thromboxane A2 (TXA2) formation in cultured vascular smooth muscle cells (VSMC) was examined. PDGF-BB behaved similar to PDGF-AB and both have features characteristic of conventional vasoconstrictor-agonists that directly increase [Ca2+]i, activate the Na+/H+ exchanger, stimulate the TXA2 formation, and induced contraction in VSMC whereas PDGF-AA induced contraction without increasing of [Ca2+]i, pHi, and TXA2 formation.

Ethanol suppresses smooth muscle cell proliferation in the postprandial state: a new antiatherosclerotic mechanism of ethanol?

Epidemiologic studies suggest that moderate amounts of ethanol may reduce cardiovascular risk. The mechanisms of the alcohol-associated risk reduction are not known exactly. Vascular smooth muscle cell proliferation represents an important phenomenon in the pathogenesis of atherosclerosis. Recently, it was suggested that metabolic changes during the postprandial phase may be important in the pathogenesis of atherosclerosis. Therefore, we evaluated the effect of postprandial plasma with and without ethanol on the proliferation of rat vascular smooth muscle cells. Identical meals containing 1 g fat/kg body wt were given with and without ethanol (38 +/- 0.5 g) to eight healthy young men. Blood was drawn hourly during an 8-h postprandial period; the plasma was separated and added to the cell cultures (0.3%, by vol). The proliferative response (DNA synthesis) of these cells was assessed by measuring the incorporation of [methyl-3H]thymidine. The maximal blood ethanol concentration of 11.5 +/- 0.6 mmol/L (mean +/- SEM) was attained within the first hour. The ingestion of the meal with ethanol led to a 20% reduction in the capacity of postprandial plasma to induce thymidine incorporation into smooth muscle cells compared with the meal without ethanol (P < 0.05). These results suggest that ethanol may reduce cardiovascular risk by modulating vascular muscle cell growth during the postprandial period. Considering the amount of time humans spend in the postprandial state during their lifetimes, these findings may be of great importance in the pathogenesis of atherosclerosis.

Renin and aldosterone secretion in pheochromocytoma. Effect of chronic alpha-adrenergic receptor blockade.

Patients suffering from pheochromocytoma characterized by an exclusive or almost exclusive excess of norepinephrine showed no (one patient) or only a moderate increase (two patients) in renin and aldosterone secretion. In those three patients with concomitant distinct hypersecretion of epinephrine, renin release (and aldosterone secretion except in one patient) was markedly enhanced. Similar results were obtained in a patient with excess norepinephrine and dopamine secretion. Renin release was markedly reduced in all patients during preoperative long-term alpha-adrenergic receptor blockade. With the exception of one patient, increased renin and aldosterone secretion was abolished. The results indicate that augmentation in renin release depends on the ratio of the different catecholamines secreted by the pheochromocytoma and their different effe-tiveness in stimulating beta-adrenergic receptors. Even in the presence of excess catecholamine secretion, there is evidence that renin secretion is predominantly mediated by beta receptors rather than by renal vascular alpha-adrenergic receptors. Normalization of catecholamine-induced enhanced renin release in patients with pheochromocytoma during chronic alpha-adrenergic receptor blockade supports the assumption that (alpha-) adrenergic blocking agents inhibit renin secretion distal to their blockade of specific adrenergic receptors. However, contrary to beta-adrenergic blockade, circadian rhythm of renin release seems to remain intact during alpha-adrenergic blockade.

Long-term experience in percutaneous transluminal dilatation of renal artery stenosis.

Percutaneous transluminal dilatation was attempted in 65 patients with renovascular hypertension. In five cases (8 percent), percutaneous transluminal dilatation could not be performed for technical reasons. In the remaining 60 patients (35 with atherosclerotic stenosis and 25 with fibromuscular dysplasia), both mean systolic and diastolic pressure fell immediately after percutaneous transluminal dilatation and remained significantly lower for a period of up to five years. Cure rates after a mean control period of 21.6 months were higher in patients with fibromuscular dysplasia (50 percent) than in those with atherosclerotic stenosis (29 percent). Improvement of blood pressure was observed in 32 percent of patients with fibromuscular dysplasia and in 48 percent of patients with atherosclerotic stenosis. Follow-up angiography in 33 cases showed occlusion of the dilated artery in two patients and recurrence of slight renal artery stenosis in nine patients. Successful redilatation could be performed in five of these cases. Furthermore, renal vein renin determinations were only of limited diagnostic or prognostic value. These results document the good long-term effect of percutaneous transluminal dilatation in patients with renal artery stenosis. Percutaneous transluminal dilatation should, therefore, be the favored procedure in patients with renovascular hypertension.

Single pericytes and pericytes in suspension are stimulated in a similar way by low-density lipoprotein.

BACKGROUND: Pericytes are regarded as the microvascular counterpart of smooth muscle cells and implicated in the regulation of blood pressure at the microvascular level. Ca2+ plays an important role in biochemical processes involved in blood pressure regulation and can be activated by low-density lipoprotein (LDL) cholesterol. OBJECTIVE: To determine whether stimulation either of single cells or of cells in suspension by LDL would produce any difference in the increase in cytosolic free calcium levels ([Ca2+]i). DESIGN AND METHODS: Single pericytes were loaded with 2 micromol/l of the Ca2+-sensitive dye Indo-1/AM. The Indo-1 fluorescence was recorded at 405 nm (Ca2+-bound) and 485 nm (Ca2+-free) after stimulation with LDL. Pericytes in suspension were loaded with 2 micromol/l of the Ca2+-sensitive dye FURA-2/AM. The FURA-2 fluorescence kinetics were recorded at 340-380 nm. Ratios of fluorescence at the two wavelengths were transformed to [Ca2+]i. RESULTS: Basal [Ca2+] levels appeared to be higher in single cells (148+/-13 nmol/l, n = 20) than they were in cells in suspension (128+/-8 nmol/l, n = 25; P= 0.0078). After stimulation with LDL the increase in [Ca2+]i in both systems was about 220% above baseline. A clear dose dependency was seen for both systems. CONCLUSIONS: Single pericytes and pericytes in suspension increase their [Ca2+]i after stimulation with LDL dose-dependently. Even though single-cell measurements revealed some technical limitations, their responses were comparable to those obtained in a cell suspension. In analogy to aortic smooth muscle cells, our results indicate that LDL might also play a blood-pressure-regulatory role in the microvasculature.

Is an increased waist : hip ratio the cause of alcohol-induced hypertension? The AIR94 study.

OBJECTIVE: The mechanisms of alcohol-associated hypertension are not known. We tested the hypothesis that the alcohol-associated increase in blood pressure may be caused in part by an alcohol-induced accumulation of abdominal fat. SUBJECTS AND METHODS: A total of 842 non-smoking men (mean +/- SD age 52 +/- 16 years) attending the air-show AIR94 in Bouchs, Switzerland, volunteered to participate in a cross-sectional study. Four alcohol consumption frequency categories were self-reported, together with weight changes since the age of 20 and during the last 2 years. Blood pressure, body weight, height and the waist : hip ratio were measured. RESULTS: The results showed that 83% of the subjects were alcohol-consumers. Systolic (analysis of variance, P = 0.002) and diastolic (P = 0.009) blood pressure and the waist : hip ratio (P>0.0001) increased with increasing alcohol consumption. The self-judged dietary fat intake increased significantly with increasing alcohol consumption. Weight changes over time were positively associated with alcohol consumption. In a regression model alcohol consumption was the fourth most important contributor to systolic and diastolic blood pressure as well as to an increased abdominal fat mass. CONCLUSION: The alcohol-associated increase in blood pressure may be caused in part by an alcohol-induced accumulation of abdominal fat. Alcohol consumption favours the development of a positive energy balance and thus the abdominal deposition of fat, which is associated with an increased blood pressure. To reduce the risk of a positive energy balance and the abdominal deposition of fat, the intake of alcohol should be minimized and physical activity increased whenever possible.

The use of self-measured blood pressure determinations in assessing dynamics of drug compliance in a study with amlodipine once a day, morning versus evening.

OBJECTIVE: To test whether the time of administration influences the therapeutic response to a calcium antagonist taken once a day. Also, the dynamics of drug compliance and its impact on blood pressure control were investigated. DESIGN: Twenty outpatients with mild-to-moderate hypertension were included in a randomized, placebo-controlled open study. In a crossover design, all of the patients received 5 mg amlodipine, either in the morning or in the evening, during two consecutive 4-week treatment periods. METHODS: Blood pressure was taken by casual measurement, ambulatory 24-h monitoring (SpaceLabs 90202) and self-measurement at home, performed with a semi-automatic oscillometric device during the whole study period. Compliance was assessed using the Medication-Event-Monitoring System (MEMS). RESULTS: Neither casual nor ambulatory day- or night-time readings detected a significant difference between morning and evening administration. However, self-measurement documented significantly greater blood pressure reductions for morning than for evening administration. The MEMS showed different compliance on the days of ambulatory monitoring (100% with both drug regimens) compared with the whole treatment period. The number of days with missed medication was thus significantly higher for the evening dosing regimen. The difference in self-measured blood pressure between the two regimens was lost if the days with missed medication were removed from the statistical analysis. CONCLUSIONS: Time of once-a-day amlodipine administration does not influence its efficacy for 24-h blood pressure control. Furthermore, the use of self-measurement and the MEMS may provide useful additional information on the pharmacodynamic impact of different dosing patterns in hypertensive patients.