Exogenous nitric oxide regulates activity and synthesis of vascular endothelial nitric oxide synthase

BACKGROUND

Nitric oxide (NO) - a major signalling molecule of the vascular system - is constitutively produced in endothelial cells (EC) by the endothelial NO synthase (eNOS). Since a reduced NO synthesis is an early sign of endothelial dysfunction and NO delivering drugs are used to substitute the impaired endothelial NO production, we addressed the effect of exogenous NO on eNOS in human umbilical venous endothelial cell cultures.

MATERIALS AND METHODS

The synthetic NO donor DETA/NO (trade name, but in the following we refer to detNO), that releases NO in a strictly first order reaction with a half life of 20 h, was used in our experiments.

RESULTS

Short-term (20-30 min) detNO treatment of EC increases the Ser(1177) phosphorylation of the constitutively expressed endothelial NOS and the production of endogenous NO generated by eNOS from [(3)H]arginine. The phosphorylation of eNOS is Akt-dependent and completely reverted by the phosphatidylinositol-3 kinase (PI-3K) inhibitor LY294002. A prolonged continuous exposure of EC to detNO 150 micromol L(-1) over a period of 24-48 h causes a reversible cell cycle arrest at G(1)-phase associated with a larger cell volume and increased cell protein content (hypertrophic phenotype of EC). The eNOS protein and mRNA of the hypertrophic cells and the generation of endogenous NO are reduced but eNOS phosphorylation could still be elevated by stimulation with vascular endothelial growth factor.

CONCLUSIONS

Our data explain clinical studies describing a short-term but not a long-term benefit of NO treatment for patients with cardiovascular risk factors. The results could be a rational approach to develop a generation of NO donors accomplishing a retarded release from NO donors that mimic the low continuous pulsatile stress-induced release of endogenous NO.

Uric acid and renal function in multiple sclerosis

OBJECTIVE

The purpose of this study was to examine the circadian distribution of creatinine and uric acid clearances in subjects with Multiple Sclerosis.

MATERIALS AND METHODS

Eleven subjects with MS, 6 women (48+/-7y) and 5 men (58+/-5y) volunteered for this circadian study. Thirteen healthy females (39+/-11y) served as controls. Data of seven healthy male controls (64+/-8 y) were extracted from a similar circadian study conducted previously. Each MS patient, and each male control had blood samples drawn around the clock, at 3h intervals (8/24h), and each collected urines over 3h periods (8/24h). Each female control contributed only one blood sample and one complete 24h urine collection. Blood and urine samples were analyzed for a number of relevant analytes: ELAM, IL-6, NO, insulin, ACTH, aldosterone, cortisol, electrolytes, lymphocytes, monocytes including creatinine and uric acid clearances. Those were standardized to an average body surface area of 1.73 m2.

RESULTS

The relevant analytes demonstrated increased synthesis of insulin, IL-6, ELAM, monocytes, and reduced concentrations of serum NO. The creatinine clearances were significantly lower in MS females than in female controls, 63+/-22 vs.108+/-18 ml/min. They were also lower than those of MS males and male controls, 107.8+/-17, 97.5+/-8.2 ml/min. Uric acid clearances in MS females were also lower 6.9+/-2.4 vs. 10.5+/-4.4 ml/min. The uric acid clearance in MS males was higher than in male controls, 7.0+/-4.5 vs. 4.0+/-1.0 ml/min.

CONCLUSIONS

The alterations in selected relevant analytes and the reduced creatinine and uric acid clearances in females but not in males, suggest a renal dysfunction in MS females. These observations may contribute to understanding better the mechanism of renal dysfunction in female patients and perhaps this may be an additional factor contributing to greater frequency of MS in females than in male subjects.

Prevention of perioperative thromboembolism in patients with atrial fibrillation

BACKGROUND

The aim of this retrospective study was to review the safety and efficacy of two regimens for the prophylaxis of perioperative thromboembolism in patients with atrial fibrillation.

METHODS

From a database of 14 801 procedures, atrial fibrillation occurred in 1.9 per cent of patients. Those not on oral anticoagulation (n = 146) received low molecular weight heparin (LMWH) before and after surgery (nadroparine 40 units per kg). Patients on oral anticoagulation before surgery (n = 136) received intravenous unfractionated heparin (UFH) after surgery at a dose adequate to maintain the thrombin time at a therapeutic level.

RESULTS

The incidence of perioperative arterial or venous thromboembolism was independent of pre-existing risk factors and occurred in 4.6 per cent of patients, without significant difference between the two regimens (P = 0.780). Logistic regression revealed that thromboembolism was significantly associated with increased perioperative mortality (odds ratio 9.5, (95 per cent confidence interval 2.5 to 35.8); P = 0.001). The rate of postoperative bleeding was 4.8 per cent in patients who had LMWH and 17.6 per cent in those who had UFH (P < 0.001).

CONCLUSION

Postoperative anticoagulation with therapeutic UFH in patients with atrial fibrillation was associated with an increased rate of bleeding without reducing the risk of thromboembolism.

Towards biosensing of arteriosclerotic nanoplaque formation using femtosecond spectroscopy

The ultrafast dynamics of proteoheparan sulfate (HS-PG) in Krebs blood substitute solution was measured using femtosecond transient absorption spectroscopy after UV excitation. Interacting with blood lipoproteins and Ca(2+) ions, the proteoglycan HS-PG is the key component of the so-called nanoplaque, the earliest stage in atherogenesis. Since tryptophan (Trp) residues are the main optically active parts of HS-PG, analogous measurements were performed on bare Trp in Krebs solution. The comparison reveals distinct differences to main characteristics of the HS-PG broadband absorption spectra. Analyzing the Trp spectra, we show that the results from transient absorption spectroscopy resemble the time constants of the chromophore ultrafast solvation dynamics that have been found by another group using fluorescence up-conversion techniques. Yet, the broadband transient absorption provides more details about the molecular dynamics, including stimulated emission, excited state absorption and resonant energy transfer. Furthermore, the absorption long time dynamics upon adding Ca(2+) to the HS-PG probe were investigated by transient absorption spectroscopy and by surface force and ellipsometry investigations. Notably, a Ca(2+)-induced conformational change responsible for arteriosclerotic nanoplaque formation was detected. Slight differences, which are only visible as broad spectral features in the sub-picosecond time scale, provide a first insight into the molecular formation of nanoplaques in blood vessels, which may yield a better understanding of the genesis of arteriosclerosis.

Reduction of atherosclerotic nanoplaque formation and size by Ginkgo biloba (EGb 761) in cardiovascular high-risk patients

Coating a silica surface with the isolated lipoprotein receptor proteoheparan sulfate (HS-PG) from arterial endothelium and vascular matrices and adding both the atherogenic VLDL/IDL/LDL lipid fraction in its native composition and Ca(2+) ions, we could observe in vitro the earliest stages of atherosclerotic plaque development by ellipsometric techniques (patent EP 0 946 876). This so-called nanoplaque formation is represented by the ternary aggregational complex of the HS-PG receptor, lipoprotein particles and calcium ions. The model was validated in several clinical studies on statins in cardiovascular high-risk patients. In eight patients who had undergone an aortocoronary bypass operation, the reduction of atherosclerotic nanoplaque formation amounted to 11.9+/-2.5% (p<0.0078) and of nanoplaque size to 24.4+/-8.1% (p<0.0234), respectively, after a 2-month therapy with Ginkgo biloba extract (2x 120 mg daily, EGb 761). Additionally, superoxide dismutase (SOD) activity was upregulated by 15.7+/-7.0% (p<0.0391), the quotient oxLDL/LDL lowered by 17.0+/-5.5% (p<0.0234) and lipoprotein(a) concentration decreased by 23.4+/-7.9% (p<0.0234) in the patients' blood. The concentration of the vasodilating substances cAMP and cGMP was augmented by 37.5+/-9.1% (p<0.0078) and 27.7+/-8.3% (p<0.0156), respectively. A multiple regression analysis between the patients' VLDL/IDL/LDL lipoprotein fraction applied in the ellipsometry measurements as well as the further risk factors oxLDL/LDL and Lp(a) on the one hand and changes in nanoplaque formation on the other hand reveals a basis for a mechanistic explanation of nanoplaque reduction under ginkgo treatment. The atherosclerosis inhibiting effect is possibly due to an upregulation in the body's own radical scavenging enzymes and an attenuation of the risk factors oxLDL/LDL and Lp(a).

Circadian distribution of serum cytokines in multiple sclerosis

AIMS

The purpose of this study was to examine circadian distribution of selected cytokine levels (IL-2, IL-10, GM-CSF, TNF-alpha, and IFN-gamma) in serum of subjects with active Multiple Sclerosis (MS) and non-MS subjects.

MATERIALS AND METHODS

Six females (36-56y) and five males (52-68y) with active MS volunteered and consented for the study conducted at Special Diagnostic Ward of this hospital. All subjects gave their medical history and were given complete physical examination. Low purine meals were served at 16:30, 07:30 and 13:00 h. Lights were "OFF' at 22:30 hr and "ON" at 06:30h. Blood collections were made at 3h intervals over a 24h period of time. Six healthy male subjects (53-76y) subjects' data were obtained from a study conducted 3 years previously using the same procedural protocol. Cytokine assays were assessed using commercial enzyme-linked immuno-absorbent procedure. Time series of average data and the range of change between the highest and lowest concentrations are presented for MS subjects along with data from non-MS subjects.

RESULTS

IL-2, IL-10, and GM-CSF levels were significantly reduced in females with MS when compared with levels of healthy subjects while their IL-6 levels were increased. The IL-6, GM-CSF and TNF-alpha levels in males with MS were below detection limits. The TNF-alpha levels were essentially similar in MS females and healthy subjects.

CONCLUSIONS

These preliminary studies, although with very small number of patients and healthy male controls appear to suggest that the circadian analysis of cytokines and other markers of immunity may have utility in understanding the pathogenesis of diseases like MS.

Simulation of cerebral hemodynamics for preoperative risk assessment

BACKGROUND

An important part of the medical treatment of many cerebrovascular diseases is the occlusion of brain supplying arteries. Until now, the risk of this intervention can only be estimated by invasive diagnostics including the risk of cerebrovascular accidents.

METHODS AND RESULTS

As a supporting tool, a computer model of the circle of Willis was designed. The model is based upon linear differential equations describing electrotechnical circuits extended non-linearly. By these means, time continuous simulations of different states and the online observation of all calculated state variables such as blood pressure and blood flow in every modeled vessel became feasible. For individual simulations, model parameters were determined by MR-angiography and boundary values by simultaneous Duplex-measurements in both carotid and vertebral arteries. State variables generated by the model behaved physiologically and the reaction of individual cerebrovascular systems in critical situations could be investigated by special scenarios. Inaccuracies concerning the determination of model parameters and boundary values of the used differential equations are likely to be resolved in the near future through a more careful and technically improved determination of these values.

CONCLUSIONS

Computer models of subjects were created taking in account the individual anatomical and non-linear physical properties of real vascular systems supplying the brain. Thereby information could be obtained concerning the hemodynamic effects of an iatrogenic vascular occlusion.

Stable expression of the vesicular GABA transporter following photothrombotic infarct in rat brain

Before exocytotic release of the inhibitory neurotransmitter GABA, this amino acid has to be stored in synaptic vesicles. Accumulation of GABA in vesicles is achieved by a specific membrane-integrated transporter termed vesicular GABA transporter. This vesicular protein is mainly located at presynaptic terminals of GABAergic interneurons. In the present study we investigated the effects of focal ischemia on the expression of the vesicular GABA transporter. Vesicular GABA transporter mRNA and protein expression was examined after photothrombosis in different cortical and hippocampal brain regions of Wistar rats. In situ hybridization and quantitative real-time RT-PCR were performed to analyze vesicular GABA transporter mRNA. Both vesicular GABA transporter mRNA-stained perikarya and mRNA expression levels remained unaffected. Vesicular GABA transporter protein-containing synaptic terminals and somata were visualized by immunohistochemistry. The pattern of vesicular GABA transporter immunoreactivity as well as the protein expression level revealed by semiquantitative image analysis and by Western blot remained stable after stroke. The steady expression of vesicular GABA transporter mRNA and protein after photothrombosis indicates that the exocytotic release mechanism of GABA is not affected by ischemia.

Circadian variation in multiple sclerosis of oxidative stress marker of DNA damage. A potential cancer marker?

OBJECTIVE

To investigate circadian rhythm (CR) of urinary creatinine and 8-hydroxy-2-deoxyguanosine (8-OHdG) in patients with Multiple Sclerosis (MS) and to present concentrations of this DNA damage marker, 5 years prior to mastectomy, in one MS study subject, and 2 years prior to biopsy confirmed a carcinoma (CA) of the prostate in one non-MS subject.

MATERIALS AND METHODS

Eleven subjects with MS (6 women 36-52 years of age and 5 men 51-68 years) volunteered for this study, carried out at Edward Hines Jr., Medical Center. Subjects were offered a general hospital diet (2400 cal in total/24h) at 16:30h, 07:30h and 13:00h. The dark (sleep) phase of the light-dark cycle extended from 22:30h to 06:30h with brief awakening for sampling at 01:00h, and 04:00h. Urine samples were collected for consecutive 3h spans beginning at 16:00-19:00h and were analyzed for creatinine and 8-OHdG. Twelve men (including 3 with type 2 diabetes) provided 21 profiles according to the same protocol used for comparison. In addition, 10 healthy women provided 24h urine samples. Statistical analysis of data was performed using the Single-Cosinor and Population-Mean Cosinor.

RESULTS

A CR was detected for creatinine in healthy men (p < 0.001) but not for MS patients. Urinary creatinine concentrations were lower in MS women than in healthy women (p = 0.015) and were lower in MS women than in men healthy or with MS (p < 0.001): Women; MS 655 +/- 76; H 1381 +/- 316; Men, MS 1830 +/- 285; H 1532 +/- 265 mg/24h vol. A CR was evident in 8-OHdG in MS (p = 0.007) and in non-MS subjects (p < 0.001) with highest values occurring at about 16:45h. The average concentrations of 8-OHdG in MS patients were similar to those in healthy subjects: Women, MS 589 +/- 125; H 794 +/- 318; Men, MS 504 +/- 156; H 591 +/- 134 picomoles/kg bw/24h vol. The 8-OHdG concentrations of a MS patient, later diagnosed with breast cancer, were found to exceed the upper 95% prediction limit in health. An increased 8-OHdG level was also noted in a non-MS subject who 2 years later received a biopsy-confirmed diagnosis of prostate CA.

CONCLUSIONS

Despite the small number of subjects in this study, a statistically significant CR was documented for 8-OHdG in urine of subjects with MS. Interestingly, the increased concentrations of DNA damage marker, the 8-OHdG, 5 years prior to mastectomy and the 2 years prior to affirmative diagnosis of prostate CA, could be the most significant clinical observations of this study. Follow-up studies of a larger population of subjects would, thus, be required to ascertain the predictive validity of such challenging observation.

Persistent anti-Dra in two pregnancies

The Drori (Dr(a)) antigen is one of the ten high-prevalence antigens of the Cromer blood system, which are carried on decayaccelerating factor (DAF, CD55). The Dr(a-) phenotype was first described in a 48-year-old Jewish woman from Bukhara. Her serum contained an antibody to a high-prevalence antigen named anti-Dra. Most known individuals with the Dr(a-) phenotype are Jews from the geographic area of Bukhara, but individuals from Japan have also been described. Antibodies in the Cromer blood group system, including anti-Dra,have never been reported to cause HDN. In most of the cases with anti-Dra examined in Israel, the antibodies have been subtyped as IgG2 and IgG4. This report is of a woman with Dr(a-) phenotype and an anti-Dr(a) titer of 256 to 512 in her serum, observed during two successive pregnancies. At birth, the RBCs of the first- and second-born child were negative and positive in the DAT, respectively, and neither manifested clinical signs of HDN. The disappearance of Cromer system antibodies, including anti-Dra in midpregnancy, has been described in a previous study. In that study, it was theorized that the antibodies in the serum of the women were adsorbed onto placental DAF. The finding of a high anti-Dra titer in two successive pregnancies in this patient, with a positive DAT for the RBCs of one of the two babies at term, differs from published reports, suggesting that a different mechanism might be involved.

[Carcinomas of the esophago-gastric junction: surgical strategies]

There is increasing incidence of adenocarcinoma of the esophagastric junction (EGJ) especially in young white men (+35% in 30 years). The reasons for this are not yet well known, however one of the main causes is gastro-esophageal-reflux disease (GERD). The differentiation of a EGT carcinoma in three subtypes is important for therapy: adenocarcinoma of the distal esophagus (type I), cardia carcinoma (type II) and subcardial gastric carcinoma (type III). The most important risk-factor for type I-cancers is "barrett's metaplasia" resulting from GERD over years. The risks for the type II- and type III-carcinomas may be obesity and high caloric and fat intake. The role of Helicobacter pylori infection and adenocarcinoma of the subcardia is unproven. Preoperative tumor staging is difficult and tumor-stage is most often underestimated (esp. in the case of a high-grade dysplasia where in 43% carcinomas one already established). Therapy for all three types of EGJ tumors is surgical. Transhiatal (rarely transthoracic) esophagectomy with lymphadenectomy and proximal gastrectomy is performed for type-I-tumors, type-II and III-tumors are treated like a gastric cancer with total gastrectomy, lymphadenectomy and distal esophagectomy. Lymph-node metastases and advanced tumor-stage are bad prognostic factors, complete tumor resection (R0 resection) with extended lymphadenectomy will improve prognosis. The results of a preoperative combined-modality therapy are encouraging, but have not yet shown a definitive benefit. In case of distant metastases, radio-chemotherapy combined with gastroenterologic treatments (e.g. esophageal prostheses, PEG, etc.) will be used as a palliative treatment option.

The effect of garlic on arteriosclerotic nanoplaque formation and size

OBJECTIVE

In an in vitro biosensor model (PCT/EP 97/05212), the interplay between different lipoproteins in arteriosclerotic nanoplaque formation, as well as aqueous garlic extract (0.2-5.0 g/l from LI 111 powder) as a possible candidate drug against arterio/atherosclerosis were tested within the frame of a high throughput screening.

METHODS

The processes described below were studied by ellipsometric techniques quantifying the adsorbed amount (nanoplaque formation) and layer thickness (nanoplaque size). A thorough description of the experimental setup has been given previously.

RESULTS

Proteoheparan sulfate (HS-PG) adsorption to hydrophobic silica was monoexponential and after approximately 30 min constant. The addition of 2.52 mmol/l Ca2+ led to a further increase in HS-PG adsorption because Ca2+ was bound to the polyanionic glycosaminoglycan (GAG) chains thus screening their negative fixed charges and turning the whole molecule more hydrophobic. Incubation with 0.2 g/l aqueous garlic extract (GE) for 30 min did not change the adsorption of HS-PG. However, the following addition of Ca2+ ions reduced the increase in adsorption by 50.8% within 40 min. The adsorption of a second Ca2+ step to 10.08 mmol/l was reduced by even 82.1% within the next 40 min. Having detected this inhibition of receptor calcification, it could be expected that the build-up of the ternary nanoplaque complex is also affected by garlic. The LDL plasma fraction (100 mg/dl) from a healthy probationer showed beginning arteriosclerotic nanoplaque formation already at a normal blood Ca2+ concentration, with a strong increase at higher Ca2+ concentrations. GE, preferably in a concentration of 1 g/l, applied acutely in the experiment, markedly slowed down this process of ternary aggregational nanoplaque complexation at all Ca2+ concentrations used. In a normal blood Ca2+ concentration of 2.52 mmol/l, the garlic induced reduction of nanoplaque formation and molecular size amounted to 14.8% and 3.9%, respectively, as compared to the controls. Furthermore, after ternary complex build-up, GE similar to HDL, was able to reduce nanoplaque formation and size. The incubation time for HDL and garlic was only 30 min each in these experiments. Nevertheless, after this short time the deposition of the ternary complex decreased by 6.2% resp. 16.5%, i.e. the complex aggregates were basically resolvable.

CONCLUSIONS

These experiments clearly proved that garlic extract strongly inhibits Ca2+ binding to HS-PG. In consequence, the formation of the ternary HS-PG/LDL/Ca2+ complex, initially responsible for the 'nanoplaque' composition and ultimately for the arteriosclerotic plaque generation, is decisively blunted.

Reduction of arteriosclerotic nanoplaque formation and size by fluvastatin in a receptor-based biosensor model

Proteoheparan sulfate can be adsorbed onto a methylated silica surface in a monomolecular layer via its transmembrane hydrophobic protein core domain. Due to electrostatic repulsion, its anionic glycosaminoglycan side chains are stretched out into the blood substitute solution, thereby representing a receptor site for specific lipoprotein binding through basic amino acid-rich residues within their apolipoproteins. The binding process was studied by ellipsometric techniques suggesting that HDL has a high binding affinity and a protective effect on interfacial heparan sulfate proteoglycan layers with respect to LDL and Ca(2+) complexation. LDL was found to be deposited strongly at the proteoheparan sulfate-coated surface, particularly in the presence of Ca(2+), apparently through complex formation 'proteoglycan-low density lipoprotein-calcium'. This ternary complex build-up may be interpreted as arteriosclerotic nanoplaque formation on the molecular level responsible for the arteriosclerotic primary lesion. In a receptor-based biosensor application, this system was tested on its reliability to unveil possible acute pleiotropic effects of the lipid lowering drug fluvastatin. The VLDL/IDL/LDL and VLDL/IDL/LDL/HDL plasma fractions from a high risk patient with dyslipoproteinaemia and type 2 diabetes mellitus showed the start of arteriosclerotic nanoplaque formation at a normal blood Ca(2+) concentration, with a strong increase at higher Ca(2+) concentrations. Nanoplaque formation and size of the HDL-containing lipid fraction remained well below that of the LDL-containing lipid fraction. Fluvastatin, whether applied acutely to the patient (one single 80 mg slow release matrix tablet) or in a 2-month medication regimen, markedly slowed down this process of ternary aggregational nanoplaque build-up and substantially inhibited nanoplaque size development at all Ca(2+) concentrations used. The acute action gave no significant change in lipid concentrations of the patient. Furthermore, after nanoplaque generation, fluvastatin, similar to HDL, was able to reduce nanoplaque formation and size. These immediate effects of fluvastatin have to be taken into consideration when interpreting the clinical outcome of long-term studies.

The effect of an HMG-CoA reductase inhibitor on arteriosclerotic nanoplaque formation and size in a biosensor model

Proteoheparan sulfate can be adsorbed to a methylated silica surface in a monomolecular layer via its transmembrane hydrophobic protein core domain. Due to electrostatic repulsion, its anionic glycosaminoglycan side chains are stretched out into the blood substitute solution, thereby representing a receptor site for specific lipoprotein binding through basic amino acid-rich residues within their apolipoproteins. The binding process was studied by ellipsometric techniques. Low-density lipoprotein (LDL) was found to deposit strongly at the proteoheparan sulfate-coated surface, particularly in the presence of Ca(2+), apparently through complex formation 'proteoglycan-LDL-calcium'. This ternary complex build-up may be interpreted as arteriosclerotic nanoplaque formation on the molecular level responsible for the arteriosclerotic primary lesion. HDL bound to heparan sulfate proteoglycan protected against LDL deposition and completely suppressed calcification of the proteoglycan-lipoprotein complex. In addition, HDL was able to decelerate the ternary complex deposition and to disrupt newly formed nanoplaques. Therefore, HDL attached to its proteoglycan receptor sites is thought to raise a multidomain barrier, selection and control motif for transmembrane and paracellular lipoprotein uptake into the arterial wall. The molecular arteriosclerosis model was tested on its reliability in a biosensor application in order to unveil possible acute pleiotropic effects of the lipid lowering drug fluvastatin. The very low-density lipoprotein (VLDL)/intermediate-density lipoprotein (IDL)/LDL and VLDL/IDL/LDL/HDL plasma fractions from a high-risk patient with dyslipoproteinemia and type 2 diabetes mellitus showed beginning arteriosclerotic nanoplaque formation already at a normal blood Ca(2+) concentration, with a strong increase at higher Ca(2+) concentrations. Nanoplaque formation and size of the HDL-containing lipid fraction remained well below that of the LDL-containing lipid fraction. Fluvastatin, whether applied acutely to the patient (one single 80 mg slow release matrix tablet) or in a 2-months medication regimen, markedly slowed down this process of ternary aggregational nanoplaque build-up and substantially inhibited nanoplaque size development at all Ca(2+) concentrations used. The acute action resulted without any significant change in lipid concentrations of the patient. Furthermore, after nanoplaque generation, fluvastatin, similar to HDL, was able to reduce nanoplaque formation and size. These immediate effects of fluvastatin have to be taken into consideration while interpreting the clinical outcome of long-term studies.

Biosensing of arteriosclerotic nanoplaque formation and interaction with an HMG-CoA reductase inhibitor

Proteoheparan sulphate can be adsorbed to a methylated silica surface in a monomolecular layer via its transmembrane hydrophobic protein core domain. As a result of electrostatic repulsion, its anionic glycosaminoglycan side chains are stretched out into the blood substitute solution, thereby representing one receptor site for specific lipoprotein binding through basic amino acid-rich residues within their apolipoproteins. The binding process was studied by ellipsometric techniques suggesting that high-density lipoprotein (HDL) has a high binding affinity and a protective effect on interfacial heparan sulphate proteoglycan layers with respect to low-density lipoprotein (LDL) and Ca2+ complexation. Low-density lipoprotein was found to deposit strongly at the proteoheparan sulphate-coated surface, particularly in the presence of Ca2+, apparently through complex formation 'proteoglycan-LDL-calcium'. This ternary complex build-up may be interpreted as arteriosclerotic nanoplaque formation on the molecular level responsible for the arteriosclerotic primary lesion. On the other hand, HDL bound to heparan sulphate proteoglycan protected against LDL deposition and completely suppressed calcification of the proteoglycan-lipoprotein complex. In addition, HDL was able to decelerate the ternary complex deposition. Therefore, HDL attached to its proteoglycan receptor sites is thought to raise a multidomain barrier, selection and control motif for transmembrane and paracellular lipoprotein uptake into the arterial wall. Although much remains unclear regarding the mechanism of lipoprotein depositions at proteoglycan-coated surfaces, it seems clear that the use of such systems offers possibilities for investigating lipoprotein deposition at a 'nanoscopic' level under close to physiological conditions. In particular, Ca2+-promoted LDL deposition and the protective effect of HDL even at high Ca2+ and LDL concentrations agree well with previous clinical observations regarding risk and beneficial factors for early stages of atherosclerosis. Considering this, the system was tested on its reliability in a biosensor application in order to unveil possible acute pleiotropic effects of the lipid lowering drug fluvastatin. The very low-density lipoprotein (VLDL)/intermediate-density lipoprotein (IDL)/LDL plasma fraction from a high risk patient with dyslipoproteinaemia and type 2 diabetes mellitus showed beginning arteriosclerotic nanoplaque formation already at a normal blood Ca2+ concentration, with a strong increase at higher Ca2+ concentrations. Fluvastatin, whether applied to the patient (one single 80 mg slow release matrix tablet) or acutely in the experiment (2.2 micromol L-1), markedly slowed down this process of ternary aggregational nanoplaque complexation at all Ca2+ concentrations used. This action resulted without any significant change in lipid concentrations of the patient. Furthermore, after ternary complex build-up, fluvastatin, similar to HDL, was able to reduce nanoplaque adsorption and size. These immediate effects of fluvastatin have to be taken into consideration while interpreting the clinical outcome of long-term studies.

Polymorphism of the serotonin-2A receptor gene (HTR2A) associated with childhood attention deficit hyperactivity disorder (ADHD) in adult women with seasonal affective disorder

INTRODUCTION

Several lines of research point to a possible overlap between seasonal affective disorder (SAD) and attention deficit hyperactivity disorder (ADHD), particularly in females. There is also emerging evidence that variation of the 5-HT2A receptor gene (HTR2A) contributes to both SAD and ADHD. The current study investigated whether variation in HTR2A was associated with symptoms of childhood ADHD in adult women with SAD.

METHOD

Sixty-six women with SAD were administered the Wender-Utah Rating Scale (WURS), which retrospectively assesses childhood ADHD, as part of an ongoing genetic study of SAD. WURS scores were compared across the three genotypic groups defined by the T102C polymorphism of HT2RA.

RESULTS

Analysis of variance indicated a significant difference in mean 25-item WURS scores across the three genotypic groups (p = 0.035). Post-hoc tests revealed that the C/C genotypic group had a significantly higher mean score than both the T/T group and T/C group. Based on previously established WURS criteria, 38% of subjects with the C/C genotype, and none with the T/T genotype, had scores consistent with childhood ADHD.

LIMITATIONS

The current sample size is small, and childhood ADHD diagnoses were based on retrospective recall.

CONCLUSION

These preliminary results suggest a possible association between variation in HTR2A, childhood ADHD, and the later development of SAD in women.

A receptor-based biosensor for lipoprotein docking at the endothelial surface and vascular matrix

Proteoheparan sulfate can be adsorbed to a methylated silica surface in a monomolecular layer via its transmembrane hydrophobic protein core domain. Due to electrostatic repulsion, its anionic glycosaminoglycan side chains are stretched out into the blood substitute solution, representing a receptor site for specific lipoprotein binding through basic amino acid-rich residues within their apolipoproteins. The binding process was studied by ellipsometric techniques showing that HDL has a high binding affinity to the receptor and a protective effect on interfacial heparan sulfate proteoglycan layers, with respect to LDL and Ca(2+) complexation. LDL was found to deposit strongly at the proteoheparan sulfate, particularly in the presence of Ca(2+), thus creating the complex formation "proteoglycan-low density lipoprotein-calcium". This ternary complex build-up may be interpreted as arteriosclerotic nanoplaque formation on the molecular level responsible for the arteriosclerotic primary lesion. On the other hand, HDL bound to heparan sulfate proteoglycan protected against LDL docking and completely suppressed calcification of the proteoglycan-lipoprotein complex. In addition, HDL and aqueous garlic extract were able to reduce the ternary complex deposition and to disintegrate HS-PG/LDL/Ca(2+) aggregates. Although much remains unclear regarding the mechanism of lipoprotein depositions at proteoglycan-coated surfaces, it seems clear that the use of such systems offers possibilities for investigating lipoprotein deposition at a "nanoscopic" level under close to physiological conditions. In particular, Ca(2+)-promoted LDL deposition and the protective effect of HDL, even at high Ca(2+) and LDL concentrations, agree well with previous clinical observations regarding risk and beneficial factors for early stages of atherosclerosis. Therefore, we believe that the system can be of some use in investigations, e.g. of the interplay between different lipoproteins in arteriosclerotic plaque formation, as well as in high throughput screening of candidate drugs to atherosclerosis in a biosensor application.