Prophylactic Intravenous Acetaminophen in Extremely Premature Infants: Minimum Effective Dose Research by Bayesian Approach

BACKGROUND

Patent ductus arteriosus (PDA) in preterm infants is associated with increased morbidities and mortality. Prophylactic treatment with cyclooxygenase inhibitors, as indomethacin or ibuprofen, failed to demonstrate significant clinical benefits. Acetaminophen may represent an alternative treatment option.

OBJECTIVE

This study evaluated the minimum effective dose of prophylactic acetaminophen to close the ductus and assessed the safety and tolerability profile in extremely preterm infants at 23-26 weeks of gestation.

METHODS

A dose finding trial with Bayesian continual reassessment method was performed in a multicenter study with premature infants hospitalized in neonatal intensive care unit. Infants of 23-26 weeks of gestation and post-natal age ≤ 12 h were enrolled. Four intravenous acetaminophen dose levels were predefined. The primary outcome was the ductus arteriosus closing at two consecutive echocardiographies or at day 7. The main secondary objectives included the safety of acetaminophen on hemodynamics and biological hepatic function.

RESULTS

A total of 29 patients were analyzed sequentially for the primary analysis with 20 infants assigned to the first dose level followed by 9 infants to the second dose level. No further dose level increase was necessary. The posterior probabilities of success, estimated from the Bayesian logistic model, were 46.1% [95% probability interval (PI), 24.9-63.9] and 67.6% (95% PI, 51.5-77.9) for dose level 1 and 2, respectively. A closing or closed pattern was observed among 19 patients at the end of treatment [65.5% (95% confidence interval (CI), 45.7-82.0)]. No change in alanine aminotransferase values was observed during treatment. A significant decrease in aspartate aminotransferase values was observed with postnatal age. No change in systolic and diastolic blood pressures was observed during treatment.

CONCLUSIONS

Minimum effective dose to close the ductus was 25 mg/kg loading dose then 10 mg/kg/6 h for 5 days in extremely preterm infants. Acetaminophen was well tolerated in this study following these doses.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04459117.

Systemic treatment with neuropeptide Y receptor Y1-antagonist enhances atherosclerosis and stimulates IL-12 expression in ApoE deficient mice

AIMS

Neuropeptide Y (NPY) and Y1 receptors are involved in the mechanisms related to the development of atherosclerosis. We investigated the effects of systemically given NPY and its receptor Y1-antagonist on the development of atherosclerosis and associated inflammatory molecules in ApoE(-/-) mice during high-fat diet.

METHODS

Five weeks old ApoE(-/-) were fed atherogenic high cholesterol diet for 8weeks. The mice were injected with two doses of NPY (50 or 100μg/kg) or Y1 receptor antagonist BIBP3226 (100μg/kg) or vehicle intraperitoneally for 8weeks. Atherosclerosis lesion areas in aortic arch and descending aortas were determined, inflammatory molecules and NPY were determined in aortic wall, spleen, liver or in serum.

RESULTS

Neuropeptide Y1 receptor antagonist, BIBP3226 (100μg/kg) increased atherosclerotic lesion areas compared to vehicle in descending aortas in ApoE(-/-) mice (p=0.021). The expression levels of macrophage-derived cytokine, interleukin-12 (IL-12) in spleens and livers were 8-fold increased with BIBP3226 (p=0.006 and p=0.003, respectively) as determined by RT-qPCR. Cholesterol levels in serum correlated positively with VCAM-1 expression (p=0.003) and negatively with NPY expression (p=0.044) in aortic wall in mice treated with BIBP 3226.

CONCLUSIONS

The results indicate that systemic treatment with Y1-antagonist enhances atherosclerosis development in ApoE deficient mice by triggering an overwhelming IL-12 production. The findings are highly valuable for evaluation of the development potential of Y1 ligands for therapeutics to treat or prevent atherosclerosis.

Neuropeptide Y polymorphism increases the risk for asthma in overweight subjects; protection from atherosclerosis in asthmatic subjects--the cardiovascular risk in young Finns study

AIMS

The role of neuropeptide Y (NPY) and its gene polymorphisms in the development of atherosclerosis has become increasingly evident. In asthma, NPY has been shown to be involved as immunomodulator. In this study, we investigated the role of two functional NPY polymorphisms, NPY-Leu7Pro (rs16139) and NPY-399C/T (rs16147) and obesity for the development of asthma as well as atherosclerosis in asthmatic and non-asthmatic subjects. Also, we measured heart rate variability (HRV) and NPY in serum since these might contribute through these polymorphisms to both diseases.

METHODS AND RESULTS

Thousand hundred and seventy six Finnish young adults were genotyped and three groups (G1-G3) were formed based on the observed diplotypes. The NPY-Pro7 allele always co-existed with the NPY-399T allele indicating complete linkage disequilibrium. Here we show that overweight (BMI≥25kg/m2) was associated with 2.5-fold increased risk for asthma in subjects with the NPY-399T allele without NPY-Pro7 allele (G2, n=716). Overweight was also associated with increased atherosclerosis determined by carotid intima media thickness (cIMT), but asthma seemed to be more significant determinant than overweight in determing cIMT having a decreasing effect. NPY concentration in serum was diplotype-driven (G1=792.2(29.5), G2=849.0(18.9), G3=873.9(45.2) pg/ml) and correlated positively with cIMT in the group having NPY-Pro7 allele (G3, n=142). However, the subjects with asthma had a negative NPY-cIMT relationship. Total HRV was increased in asthma and correlated negatively with cIMT irrespective of the NPY genotype.

CONCLUSIONS

Overweight together with the NPY-399T allele without NPY-Pro7 allele was associated with increased risk for asthma. Atherosclerosis was decreased in subjects with asthma depending on the NPY genotype. The results reveal novel insights into the genetics and biology of the relationship of atherosclerosis and asthma.

Inflammatory effects of blood leukocytes: association with vascular function in neuropeptide Y proline 7-genotyped type 2 diabetes patients

OBJECTIVE

We investigated the associations of inflammatory blood cell activation with vascular parameters in patients with type 2 diabetes to elucidate the possible mechanisms of accelerated atherosclerosis observed in subjects with the Leucine 7 to Proline 7 polymorphism (Leu7Pro) in the neuropeptide Y (NPY).

METHODS

Our study included 31 Caucasian patients with type 2 diabetes; 12 of them had the Leu7Pro7 (heterozygous), and 19 had the Leu7Leu7 (wild type) genotype. Vascular parameters were determined by ultrasound methods. Leukocyte analyses were performed from blood samples using flow cytometry. NPY concentrations were determined in plasma.

RESULTS

The amount of platelet-granulocyte complexes was positively correlated with NPY concentration (p=0.008) and carotid intima-media thickness (p=0.035) in the Leu7Pro7 group. Interferon gamma (IFN-γ) expression in monocytes correlated negatively with brachial artery flow-mediated dilatation also in the Leu7Pro7 group (p=0.037). The expression of tissue factor on monocytes correlated negatively with brachial artery diameter in the Leu7Pro7 patients as well (p=0.019).

CONCLUSION

The results indicate significant associations between inflammatory cell activation in blood and vascular atherosclerosis in genetically prone subjects, and provide possible mechanistic information about the role of NPY and the Leu7Pro polymorphism in the development of atherosclerosis.

The effect of endogenous preproneuropeptide Y leucine 7 to proline 7 polymorphism on growth and apoptosis in primary cultured HUVECs

Neuropeptide Y (NPY) is a universally expressed neuropeptide involved in the regulation of several physiological functions. The rather common leucine7 to proline7 (L7P) polymorphism in the signal peptide of preproNPY is a functional substitution, which changes the processing and release of NPY in cells. The mutation is associated with altered lipid levels and accelerated atherosclerosis in humans. Based on previous studies, we investigated the effect of the Pro7 allele in endothelial cells, which are known to play a role in the development of atherosclerosis. Cell proliferation and apoptosis were studied in primary cultured, genotyped human umbilical vein endothelial cells (HUVECs). Our results indicate that cells with the [p.L7]+[p.P7] genotype seem to have a tendency to be more sensitive to the growth stimulating effect of NPY and less sensitive to the effect of vascular endothelial growth factor compared to cells with the [p.L7]+[p.L7] genotype. Additionally, cells with the [p.L7]+[p.P7] genotype seem to be more sensitive to apoptosis than [p.L7]+[p.L7] cells. We speculate that the L7P substitution in preproNPY might cause a state of cellular pre-senescence, leading to endothelial dysfunction. This might be one reason for the associations of the L7P polymorphism with atherosclerosis and type II diabetes found in clinical studies.

Impact of the Leu7Pro Polymorphism of preproNPY on Diurnal NPY and Hormone Secretion in Type 2 Diabetes

Neuropeptide Y (NPY) is a sympathetic neurotransmitter that plays a role in e.g. circulation, hormone release and angiogenesis. Earlier studies have shown that the Leucine 7 to Proline 7 (Leu7Pro) polymorphism of preproNPY is associated with increased risk for vascular complications in type 2 diabetes. The mechanism for this maybe altered transmitter and hormone levels or altered cardiovascular functions, which have been observed in healthy subjects having the Leu7Pro polymorphism. The current study was undertaken to explore if the Leu7Pro polymorphism has an impact on these functions in subjects with type 2 diabetes. Diurnal measurements were performed for Finnish Caucasian type 2 diabetes patients of two preproNPY genotypes (matched by sex, age, BMI, duration of diabetes and HbA1c) in resting position to prevent sympathetic stimulation. Standard meals were offered during the 24-hour study period. Nine subjects with the Leu7Pro polymorphism and ten subjects without this polymorphism were studied. Plasma concentrations of NPY, glucose, insulin, cortisol, prolactin and leptin were measured by taking blood samples at 20 time points (from 8 a.m. to 8 a.m.). Heart rate and blood pressure were measured at the same time points. The results show that NPY concentrations were similar in both preproNPY genotypes. Glucose, insulin, cortisol and leptin concentrations as well as heart rate and blood pressure were also similar. However, a significant difference between genotypes was found in the association of NPY concentrations with cortisol concentrations (p for difference=0.002). Also a statistically significant negative association of plasma NPY levels with plasma glucose levels was found in both genotypes. Since no impact of preproNPY genotype on mean NPY or hormone levels were detected in subjects with type 2 diabetes, the mechanisms for the increased risk for diabetic complications in the subjects with the Leu7Pro polymorphism need to be further explored.

Leucine 7−proline 7 polymorphism in the signal peptide of neuropeptide Y is not a risk factor for exudative age-related macular degeneration

PURPOSE

Because of the regulatory role of neuropeptide Y (NPY) in angiogenesis, we set out to determine the presence of the leucine 7-proline 7 (Leu7Pro) polymorphism in exudative age-related macular degeneration (AMD) patients and to analyse its implications.

METHODS

Genotype analysis of the Leu7Pro polymorphism in the signal peptide region of the human prepro-NPY was performed in blood samples from exudative AMD patients (n = 240) and control subjects (n = 79).

RESULTS

In all, 11% of exudative AMD patients and 14% of control subjects exhibited the NPY signal peptide Leu7Pro polymorphism. There were no statistically significant differences in Leu7Pro polymorphism frequency between the exudative AMD and control cases, as analysed by Fisher's exact two-sided test.

CONCLUSIONS

Leu7Pro polymorphism in the signal peptide region of the human prepro-NPY is not a risk factor for exudative AMD.

The Leu7Pro Polymorphism of Neuropeptide Y is Associated with Younger Age of Onset of Type 2 Diabetes Mellitus and Increased Risk for Nephropathy in Subjects with Diabetic Retinopathy

Several studies have shown genetic predisposition for diabetic complications. The leucine7 to proline7 (Leu7Pro) polymorphism of preproNPY has been shown to be a risk factor for diabetic retinopathy in type 1 diabetes. In the current study we examined the contribution of this polymorphism on the progression of retinopathy in Caucasian type 1 and type 2 diabetes patients. Patients with type 2 diabetes and the Leu7Pro polymorphism developed retinopathy at younger age because of markedly earlier disease onset of diabetes (RC- 6.8, 95% CI-12.2 - [- 1.5]), but no association of the Leu7Pro polymorphism with the current severity of retinopathy was detected. A strong association of the polymorphism with proteinuria in type 2 diabetes patients with retinopathy could be detected (OR 3.1, 95% CI 1.1-8.8); 31% of subjects having both retinopathy and proteinuria had the polymorphism compared to only 13% of retinopathy patents without concomitant proteinuria (p = 0.032). Plasma concentrations of NPY were increased in subjects with proteinuria (79.2+/-28.4 and 64.7+/-26.2 pmol/l, p = 0.001). These results suggest that the Leu7Pro polymorphism could be used to predict earlier onset of type 2 diabetes and retinopathy, and increased risk for diabetic nephropathy.

Changes in the soleus muscle architecture after exhausting stretch-shortening cycle exercise in humans

This study focused on the architectural changes in the muscle-tendon complex during the immediate and secondary (delayed) reductions of performance (bimodal recovery) caused by an exhaustive rebound type stretch-shortening cycle (SSC) exercise. The isometric plantar flexor torque during maximum voluntary contraction (MVC) was measured together with recording of electromyography (EMG) and ultrasonography from the soleus muscle before (BEF), after (AFT), 2 h (2H), 2 and 8 days (2D, 8D) after the SSC exercise (n=8). The performance variables (MVC torque and EMG activation) followed the bimodal recovery patterns. This was not the case in the changes of the fascicle length and muscle thickness. The relative torque changes in MVC correlated positively (R=0.78, P=0.02) to the corresponding averaged EMG changes between BEF and 2H (BEF-->2H); the significance disappeared in the comparison between 2H and 2D (2H-->2D), during which period MVC showed a secondary reduction. The relative torque changes in MVC showed no correlation with the changes in muscle thickness between BEF-2H. However, this correlation between 2H-2D was negative (R=-0.85, P<0.01). The fascicle shortening/average EMG ratio in MVC increased at 2H, and then decreased more at 2D than 2H (P<0.05). Thus, the secondary performance decline was not related to the corresponding EMG reduction but to the increased muscle thickness, which peaked at 2D. The results suggest clearly that the secondary decline in MVC could be related to the increase in muscle volume.

Mitochondrial targeting signal in human neuropeptide Y gene

Neuropeptide Y (NPY) is universally expressed in many different neuronal and non-neuronal cells. Human NPY gene has two in-frame kozak sequences and thus, has potentially two translation initiation sites producing two NPY peptides with different molecular weights. In the present study, the intracellular location of NPY was studied in endothelial cells endogenously expressing NPY, and in neuronal (SK-N-BE) and non-neuronal (CHO-K1) cells transfected with NPY-GFP-constructs. By mutating kozak sequences we discovered that kozak-1 directs the NPY peptide to secretory vesicles, and kozak-2 is a prerequisite for mitochondrial targeting. If both kozak sequences are present, non-neuronal cells seem to benefit leaky scanning to initiate translation at both initiation sites, in contrast to neuronal cells, which prefer the kozak-1. This finding suggests that both the kozak sequences of NPY mRNA can be used in the translation depending on the cell type. The size and the function of the novel NPY fragment routed to mitochondria remains to be determined.

The Leu7Pro polymorphism of preproNPY is associated with decreased insulin secretion, delayed ghrelin suppression, and increased cardiovascular responsiveness to norepinephrine during oral glucose tolerance test

CONTEXT

Neuropeptide Y (NPY) plays a role in angiogenesis, cardiovascular regulation, and hormone secretion. The leucine7 to proline7 (Leu7Pro) polymorphism of preproNPY is associated with vascular diseases and has an impact on hormone levels in healthy subjects.

OBJECTIVE

The current study investigated the role of the Leu7Pro polymorphism in metabolic and cardiovascular autonomic regulation.

DESIGN AND SUBJECTS

A 5-h oral glucose tolerance test was performed on 27 healthy volunteers representing two preproNPY genotypes (Leu7/Pro7 and Leu7/Leu7) matched for age, sex, body mass index and physical activity.

MAIN OUTCOME MEASURES

Simultaneously we performed cardiovascular autonomic function tests and plasma measurements of sympathetic transmitters, glucose, insulin, and ghrelin.

RESULTS

The subjects with Leu7/Pro7 genotype had decreased plasma NPY, norepinephrine (NE), and insulin concentrations and insulin to glucose ratios. The suppression of ghrelin concentrations after glucose ingestion was delayed in these subjects. They also had increased heart rate variability indices and baroreflex sensitivity. However, they displayed significant negative association of NE concentration with variability of low-frequency R-R-intervals and with baroreflex sensitivity.

CONCLUSIONS

The Leu7Pro polymorphism of preproNPY is related to decreased level of basal sympathetic activity, decreased insulin secretion, and delayed ghrelin suppression during oral glucose tolerance test. The increased responsiveness of autonomic functions to NE associated with the polymorphism may be connected to increased cardiovascular vulnerability.

Ligand-induced α2-adrenoceptor endocytosis: relationship to Gi protein activation

Most G protein-coupled receptors are desensitized by a uniform two-step mechanism: phosphorylation followed by arrestin binding and internalization. In this study we explored the time-, ligand-, and concentration dependence of alpha2-adrenoceptor internalization in human embryonal kidney (HEK-293) cells expressing alpha2A- and alpha2B-adrenoceptors. We also explored the relationship between ligand-induced receptor internalization and agonist efficacy, determined with a [35S]GTPgammaS binding assay. The results showed rapid dose-dependent internalization of both alpha2A- and alpha2B-receptors; the extent of internalization was directly proportional to agonist efficacy. The agonist UK 14,304 had a subtype-specific high efficacy at alpha2A-AR and dexmedetomidine at alpha2B-AR. Agonist-induced [35S]GTPgammaS binding was totally blocked by pretreatment with pertussis toxin (PTX) for both receptor subtypes, while only about 50% of the internalization was blocked by PTX. The results indicate that the extent of internalization of alpha2A-AR and alpha2B-AR is proportional to agonist efficacy, but only partly dependent on Gi protein coupling.

The effects of muscle history on short latency stretch reflex response of soleus muscle

The purpose of the present study was to investigate the combined effects of muscle history, activation and stretching velocity on short latency stretch response (SLR). Stretches (70, 120 and 200 deg s-1) were elicited to both passive and active (10-25% MVC) triceps surae muscle with constant (ISO), lengthened (LEN) or shortened (SHO) muscle length. Under the passive SHO pre-condition both SLR amplitude and reflex torque (RT) decreased where as latency increased compared with the passive ISO pre-condition. Such observations were absent in active trials. Stretches applied to a lengthening passive muscle (LEN) resulted in smaller SLR amplitude and RT compared with passive ISO. In active muscle the stretch response increased with stretching velocity in ISO and SHO. However, in LEN there was large interindividual variability and no velocity dependent increase in SLR amplitude was observed. Smaller amplitude and longer latency of passive SLR in SHO could result from increased slack in the intrafusal fibres, which may be compensated by fusimotor activation during the active condition. The mechanism behind the smaller amplitude in passive LEN and the lack of velocity dependence in active LEN may be related to changes in motoneuron pool excitability or changes in the spindle sensitivity to stretch.

Leucine 7 to proline 7 polymorphism in the preproneuropeptide Y is associated with proteinuria, coronary heart disease, and glycemic control in type 1 diabetic patients

OBJECTIVE

Neuropeptide Y is a potent vasoconstrictor thought to enhance the development of atherosclerosis. The leucine 7 to proline 7 (Leu7Pro) polymorphism, located in the signal peptide part of the human preproneuropeptide Y, has been associated with serum lipid levels, intima-media thickness of the common carotid arteries, and diabetic retinopathy in type 2 diabetic patients. Therefore, we investigated the impact of the Leu7Pro polymorphism on diabetic nephropathy, cardiovascular risk factors, and cardiovascular disease in type 1 diabetic patients.

RESEARCH DESIGN AND METHODS

A total of 996 patients from the Finnish Diabetic Nephropathy study were studied in a case-control, cross-sectional study. The carrier frequency of the Pro7 substitution was 13% in the entire study population.

RESULTS

The Pro7 substitution was more common in patients with proteinuria than in those with a normal albumin excretion rate (16 vs. 11%, P < 0.05). Patients with the Pro7 allele had worse glycemic control (HbA(1c) 8.8 vs. 8.5%, P < 0.005), more coronary heart disease (CHD) (14 vs. 8%, P < 0.05), and higher serum triglycerides (1.65 vs. 1.35 mmol/l, P < 0.005) than patients with the wild-type genotype. There were no differences in the plasma neuropeptide Y levels between the patients with Pro7 compared with those with the wild-type genotype. The Leu7Pro polymorphism was independently associated with HbA(1c) (P < 0.001), proteinuria (P < 0.01), and CHD (P < 0.01) in multiple regression analyses.

CONCLUSIONS

We conclude that the Leu7Pro polymorphism may contribute to the genetic susceptibility to diabetic nephropathy and CHD in type 1 diabetic patients, possibly by influencing glycemic control and triglycerides.

Neuropeptide Y and Y2-receptor are involved in development of diabetic retinopathy and retinal neovascularization

BACKGROUND

Neuropeptide Y is a sympathetic neurotransmitter, a potent endothelium-derived angiogenic factor and a vascular mitogen. We have studied the role of the functional leucine7 to proline7 polymorphism of the signal peptide region of preproneuropeptide Y (prepro-NPY) as a genetic susceptibility factor for diabetic retinopathy. In addition, we investigated the role of the NPY Y2-receptor as a putative mediator of angiogenic NPY signaling in the retina.

METHODS

Frequencies of proline7 (Pro7) carriers in the prepro-NPY were determined in type 1 and type 2 diabetes patients having retinopathy, in type 2 diabetes patients without retinopathy and in healthy control subjects. The role of Y2-receptor in hyperoxemia-induced retinal neovascularization was investigated in Y2-receptor knockout mice (Y2-/-) and in rats administered Y2-receptor mRNA antisense oligonucleotide.

RESULTS

The carriers having Pro7 in the preproNPY are markedly over-represented among type 2 diabetes patients with retinopathy compared to type 2 diabetes patients without retinopathy and to the population control. Neonatal exposure to hyperoxia resulted in development of retinal neovascularization that was prevented in Y2(-1-) -mice, and significantly inhibited in rats treated with the Y2-receptor antisense oligonucleotide.

CONCLUSIONS

NPY and Y2-receptor play important roles in diabetic retinopathy and retinal neovascularization and are thus potential new targets for drug molecules for treatment of retinopathy.

alpha 2B-Adrenoceptor levels govern agonist and inverse agonist responses in PC12 cells

Receptor density is an important determinant of cellular effector responses to receptor activation. We analysed cytosolic Ca(2+) responses to alpha(2)-adrenergic agents in PC12 cells expressing human alpha(2B)-adrenergic receptors (AR) at two densities (3.8 and 1.3 pmol/mg protein). The efficacy (E(max)) of agonists was greater in cells with higher receptor expression; while the potency (EC(50)) of norepinephrine and oxymetazoline was independent of alpha(2B)-AR levels. Several classical alpha(2)-AR antagonists behaved as either partial or inverse agonists in a receptor density-dependent fashion. No apparent structural similarities were found among the inverse agonists, precluding simple predictions of inverse agonist activity. Transfected PC12 cells expressing alpha(2B)-AR at relatively high density would be a useful approach to screen inverse agonists for this class of receptors. Our results further indicate that receptor density significantly influences the properties of ligands, not only of partial agonists as predicted by classical receptor theory, but also of antagonists and full agonists.

Constitutive precoupling to G(i) and increased agonist potency in the alpha(2B)-adrenoceptor

The human alpha(2B)-adrenoceptor (alpha(2B)-AR) was mutated by substituting the D(3.49) aspartate in position 109 with an alanine (alpha(2B)-D109A) in the conserved DRY sequence at the cytoplasmic face of TM3. We studied the effects of the mutation on agonist binding and on receptor activation in CHO cells, including possible inverse agonism monitored by measuring intracellular Ca(2+) concentrations ([Ca(2+)](i)). The mutated receptor had increased binding affinity for agonists, especially dexmedetomidine (3.8-fold). The increased affinity was abolished by pretreatment of the cells with pertussis toxin. The mutation produced constitutive receptor activity evidenced as increased basal [Ca(2+)](i) and increased potency and efficacy of agonists to elicit Ca(2+) responses. The imidazoline derivative RX821002 functioned as an inverse agonist only through the alpha(2B)-D109A, reducing [Ca(2+)](i). The results thus indicate that this mutation causes constitutive receptor-G(i)-protein precoupling, and that the D(3.49) aspartate residue of the DRY motif is involved in controlling coupled and uncoupled conformations of alpha(2B)-AR.

Changes in diurnal sympathoadrenal balance and pituitary hormone secretion in subjects with Leu7Pro polymorphism in the prepro-neuropeptide Y

Neuropeptide Y (NPY) is an important neurotransmitter in the central and peripheral nervous systems. It has a regulatory role in cardiovascular and metabolic functions and control of hormone release. The leucine 7 to proline 7 (Leu7Pro) polymorphism in the signal peptide of prepro-NPY is associated with increased blood lipid levels, accelerated atherosclerosis, and diabetic retinopathy. This study elucidated the role of this polymorphism in diurnal cardiovascular, metabolic, and hormonal functions of healthy subjects during rest. The two study groups comprised individuals with different genotype, but they were matched for age and body mass index. Subjects with the Leu7Pro polymorphism had significantly lower plasma NPY and norepinephrine concentrations, lower insulin concentrations, higher glucose concentrations, and lower insulin-glucose ratio in plasma than the controls. Heart rate was significantly higher during daytime in the subjects with Leu7Pro polymorphism. Furthermore, these subjects had significantly lower prolactin concentrations in plasma. Systolic and diastolic blood pressure, serum free fatty acid and plasma leptin, ACTH, cortisol, LH, FSH, TSH, free thyroxin, and melatonin concentrations were similar during the 24-h period, compared with controls. These results show that genetically determined changes in NPY levels lead to widespread consequences in the control of sympathoadrenal, metabolic, and hormonal balance in healthy subjects.

The Leu7Pro polymorphism of the neuropeptide Y gene regulates free fatty acid metabolism

The Leu7Pro polymorphism in the signal peptide of the preproneuropeptide Y (NPY) has been associated with dyslipidemias and free fatty acid (FFA) levels during exercise. The association of this polymorphism with insulin sensitivity has not been studied. In this study, the Leu7Pro polymorphism was determined in 2 groups of nondiabetic middle-aged subjects (n = 266 and n = 295). Insulin sensitivity was measured with the hyperinsulinemic euglycemic clamp (n = 266) or with an intravenous glucose tolerance test (IVGTT, n = 295). First-phase insulin secretion was determined as insulin area under the curve (AUC) during the first 10 minutes of the IVGTT. FFAs were measured both in the fasting state and during the hyperinsulinemic clamp. The Leu7Pro polymorphism of the NPY gene was not associated with the rates of whole body glucose uptake, insulin sensitivity index, insulin secretion during the IVGTT, or insulin AUC during the oral glucose tolerance test. However, the Pro7 allele was associated with low FFA levels both in the fasting state (P =.043) and during the hyperinsulinemic clamp (P =.003). In conclusion, the Leu7Pro polymorphism of the NPY gene associates with alterations in FFA metabolism but does not have an impact on insulin sensitivity, insulin secretion, or glucose metabolism.

Agonist-dependent trafficking of alpha2-adrenoceptor subtypes: dependence on receptor subtype and employed agonist

Many G protein-coupled receptors (GPCRs) are internalized from the plasma membrane after agonist exposure. Previously, marked agonist-induced internalization of human alpha2A- and alpha2B-adrenergic receptors (AR) was observed in transfected neuronal rat pheochromocytoma (PC12) cells; alpha2A- and alpha2B-AR were internalized into partly distinct intracellular vesicles (Olli-Lähdesmäki et al., J. Neurosci. 19, 9281-9288, 1999). In this paper, the extent of alpha2-AR internalization was quantitated in human embryonic kidney (HEK-293) and PC12 cells by combined application of cell surface biotinylation and ELISA methods, which allow measurement of protein trafficking in intact, differentiated and undifferentiated cells. Significant subtype-specific (but not cell type-dependent) trafficking of human alpha2-AR was observed by quantitation and immunocytochemistry. Agonist-induced sequestration of alpha2B-AR was markedly reduced after blocking the formation of clathrin-coated vesicles by hyperosmotic sucrose pretreatment. The sequestration of alpha2A-AR was partly inhibited after sucrose pretreatment but could be further reduced after inhibiting the formation of both clathrin-coated and caveolin vesicles by combined pretreatment with hyperosmotic sucrose and filipin. Differences were also observed in the recycling of alpha2A- and alpha2B-AR. The extent of maximal agonist-induced sequestration in PC12 cells was not directly dependent on relative agonist efficacy.

cDNA cloning, expression studies and chromosome mapping of human type I serine/threonine kinase receptor ALK7 (ACVR1C)

Transforming growth factor-beta (TGF-beta) superfamily related growth factors signal by binding to transmembrane type I and type II receptor serine/threonine kinases (RSTK), which phosphorylate intracellular Smad transcription factors in response to ligand binding. Here we describe the cloning of the human type I RSTK activin receptor-like kinase 7 (ALK7), an orthologue of the previously identified rat ALK7. Nodal, a TGF-beta member expressed during embryonic development and implicated in developmental events like mesoderm formation and left-right axis specification, was recently shown to signal through ALK7. We found ALK7 mRNA to be most abundantly expressed in human brain, pancreas and colon. A cDNA encoding the open reading frame of ALK7 was obtained from a human brain cDNA library. Furthermore, a P1 artificial chromosome (PAC) clone containing the human ALK7 gene was isolated and fluorescent in situ hybridization (FISH) on metaphase chromosomes identified the gene locus as chromosome 2q24.1-->q3. To test the functionality of the ALK7 signaling, we generated recombinant adenoviruses containing a constitutively active form of ALK7 (Ad-caALK7), which is capable of activating downstream targets in a ligand independent manner. Infection with Ad-caALK7 of MIN6 insulinoma cells, in which ALK7 has previously been shown to be endogenously expressed, led to a marked increase in the phosphorylation of Smad2, a signaling molecule also used by TGF-betas and activins.

Subtype-specific neuronal differentiation of PC12 cells transfected with alpha2-adrenergic receptors

Cells of the PC12 rat pheochromocytoma cell line acquire characteristics of sympathetic neurons under appropriate treatment. Stably transfected PC12 cells expressing individual alpha2-adrenergic receptor (alpha2-AR) subtypes were used to assess the role of alpha2-ARs in neuronal differentiation and to characterise the signalling pathways activated by the alpha2-AR agonist epinephrine in these cells. The effects of alpha2-AR activation were compared with the differentiating action and the signalling mechanisms of nerve growth factor (NGF). Epinephrine induced neuronal differentiation of PC12alpha2 cells through alpha2-AR activation in a subtype-dependent manner, internalization of all human alpha2-AR subtypes, and activation of mitogen-activated protein kinase (MAPK) and the serine-threonine protein kinase Akt. Epinephrine and NGF showed synergism in their differentiating effects. The MAPK kinase (MEK-1) inhibitor PD 98059 abolished the differentiating effect of epinephrine indicating that the differentiation is dependent on MAPK activation. Activating protein-1 (AP-1) DNA-binding activity was increased after epinephrine treatment in all three PC12alpha2 subtype clones. Evaluation of the potential physiological consequences of these findings requires further studies on endogenously expressed alpha2-ARs in neuronal cells.

The dilemma of suspicious urine cytology in patients being followed for bladder cancer

BACKGROUND AND AIMS

Urine cytology is gold standard for clinical tests used in the diagnosis and follow-up of bladder cancer. Cytology, however, exhibits variable sensitivity depending on tumour grade and interpretation of urine specimens is highly dependent on the skill of the examiner. Furthermore, a "suspicious" cytology report (class III) makes clinicians uncomfortable. In these cases, a more objective test, such as the BTA stat Test, may be useful in providing clarification. The aim of this study was to evaluate the dilemma of suspicious routine urine cytology and to determine whether the BTA stat Test provides diagnostic aid in this rare but controversial category.

MATERIAL AND METHODS

506 consecutive patients who were being followed for bladder cancer were included in the study. A voided urine sample was obtained prior to routine follow-up cystoscopy and split for culture and testing with the BTA stat Test. Clinical status of the disease was evaluated in patients with suspicious urine cytology, and the diagnostic aid of the BTA stat Test in these patients was determined.

RESULTS

A total of 57 patients (11.3%) had urine cytology classified as suspicious. The BTA stat Test was positive in 29 (50.9%) and negative in 28 (49.1%) patients. Nineteen (33.3%) patients had recurrence at routine cystoscopy. Of the remaining 38 patients, 10 were further investigated due to a positive BTA stat Test. Two additional recurrences were detected bringing the total number of recurrences to 21 (36.8%), 48.3% (14/29) of the patients with positive and 25.0% (7/28) of the patients with negative BTA stat Test had recurrence (p = 0.069). Overall, 65.5% (19/29) of the patients with a positive BTA stat Test were found to have recurrence either at routine cystoscopy, at further investigations, or at the next cystoscopy compared to that of 35.7% (19/28) in those with negative testing (p = 0.024). The overall sensitivity of the BTA stat Test was 66.7%, and the specificity was 58.3%.

CONCLUSIONS

At least a third of the patients under follow-up for bladder cancer with suspicious cytology had a recurrence, indicating that these patients are a risk group for recurrence. More importantly, a BTA stat Test result seems to provide some help in distinguishing those patients with very high risk for recurrence, for whom invasive further investigations should be conducted and a close follow-up policy maintained.

Enhancing biological phosphorus removal from municipal wastewater with partial simultaneous precipitation

Pilot-scale tests to enhance phosphorus removal with ferrous sulphate in a biological phosphorus and nitrogen removal process (modified UCT) for treating municipal wastewater were performed. The results indicated that Fe(II) competes with the BioP organisms and will inhibit the biological phosphorus removal process completely at doses exceeding 9 g m(-3) of Fe(II). The goal of an effluent P level of 0.5 mg l(-1) can be attained with 5 g m(-3) of Fe(II). A consistent effluent concentration of 0.3 mg l(-1) could not be achieved with this method. A centrifugation method to evaluate the dewatering properties of sludge was developed. Comparison of the settling and dewatering properties between activated sludge from the pilot plant and a full-scale simultaneous precipitation process indicated no consistent differences between them. The poor settling properties are due to the long sludge retention time needed by nitrification and not to the biological phosphorus removal process.

Enhanced exercise-induced GH secretion in subjects with Pro7 substitution in the prepro-NPY

The leucine 7 to proline 7 (Leu7Pro) polymorphism in the signal peptide of NPY is associated with high blood lipid concentrations and accelerated rate of atherosclerosis as well as diabetic retinopathy. Also, healthy subjects with this polymorphism have increased NPY secretion during sympathetic stimulation. Because NPY may regulate GH release and ghrelin may regulate NPY formation, we studied the effects of the Leu7/Pro7 genotype on GH, ghrelin, and IGF-I secretion during standardized cycle-ergometer exercise. Furthermore, we studied the effect of the Leu7/Pro7 genotype on diurnal GH secretion in rest in a separate study. The subjects with Leu7/Pro7 genotype had 54% higher maximal increases in the plasma GH concentrations than the controls during exercise. There were no significant differences in the ghrelin or IGF-I concentrations during exercise among the groups. Furthermore, there were no differences in diurnal GH secretion between the genotypes. The results indicate that the prepro-NPY genotype has an influence on GH response during exercise in humans. The clinical significance of this finding is not known, and further studies are needed to evaluate whether the observed change in GH secretion during exercise could play a role in promoting diseases.

The mismatch negativity as an index of temporal processing in audition

OBJECTIVES

The relation of the mismatch negativity (MMN) elicitation with behavioral stimulus discrimination as well as the replicability of the MMN was evaluated for intervals between paired tones.

METHODS

The MMN, obtained in a passive oddball paradigm in two sessions separated by 4-21 days and behavioral responses (button presses to target stimuli) in a separate session were recorded from 10 adult healthy subjects. The standard stimulus (P=0.79) was a tone pair separated by a 120 ms silent inter-stimulus interval (ISI) and the deviant stimuli were tone pairs with an ISI of 100, 60, and 20 ms (P=0.07 for each).

RESULTS

The 20 and 60 ms ISI deviant tone pairs elicited a significant MMN during both recording sessions and they were also behaviorally discriminated, whereas neither did the 100 ms ISI deviant pair elicit significant MMN nor was it behaviorally discriminated. Furthermore, there was a significant correlation between the MMN and reaction times to the 20 and 60 ms ISI deviant pairs. The 20 ms ISI deviant stimulus elicited highly replicable MMNs (r=0.75), whereas the less well discriminated 60 ms ISI deviant pair did not (r=0.60).

CONCLUSIONS

The MMN reflects discrimination accuracy of temporal sound intervals. Furthermore, when the physical difference between the standard and deviant tone pair in the temporal domain is large, it is elicited with high reliability.

Antenatal and early postnatal dexamethasone treatment decreases cortisol secretion in preterm infants

Glucocorticoids are used antenatally to accelerate the maturation of fetal respiratory and cardiovascular systems when a threat of preterm delivery exists. Postnatally, they are used to prevent and treat respiratory distress syndrome. This study investigates the effects of antenatal (ACT) and early postnatal corticosteroid treatment (PCT) on serum cortisol and plasma catecholamine and adenosine 3',5'-cyclic monophosphate (cAMP) concentrations in preterm neonates. The infants in the ACT group had a significantly lower cortisol concentration than the infants in the non-ACT group on the first day of life. After birth, the infants were further divided into non-PCT and PCT groups. PCT suppressed cortisol levels significantly after 2 days, and the cortisol levels were still lower 2 days after discontinuation of PCT. No effect of PCT on plasma cAMP or catecholamine concentrations was observed. The results indicate that both ACT and a short PCT can significantly suppress basal cortisol levels in preterm infants.

Adrenocorticotropin and corticotropin-releasing hormone tests in preterm infants

The short ACTH test is used in evaluating the hypothalamo-pituitary-adrenal axis (HPA-axis) in preterm neonates after dexamethasone treatment. This test mainly examines primary adrenal suppression but is also used as a method to test secondary adrenal insufficiency because long-term deprivation of ACTH causes atrophy of the adrenal cortex. The CRH test, on the other hand, directly examines the function of the pituitary. We tested 18 infants in the neonatal intensive care unit with both the ACTH test and the CRH test to determine which of these two tests more reliably demonstrates HPA-axis suppression. One patient had normal responses both in the ACTH test and in the CRH test when the limit of 360 nmol/L was used as a sign of proper cortisol secretion. In four cases the patients' cortisol secretion would have been regarded as normal by the low-dose ACTH test, whereas the CRH test did not show an adequate cortisol response. In conclusion, the ACTH test did not reliably indicate HPA-axis suppression after a short (<2 weeks) course of dexamethasone therapy in this study. Therefore, whether the infant is or will be under acute stress after short glucocorticoid treatment, ensuring adequate cortisol secretion with the CRH test should be considered.

Weekly mitomycin C followed by monthly bacillus Calmette-Guerin or alternating monthly interferon-alpha2B and bacillus Calmette-Guerin for prophylaxis of recurrent papillary superficial bladder carcinoma

PURPOSE

We evaluated alternatives to bacillus Calmette-Guerin (BCG) monotherapy using a new combination of chemotherapy and immunotherapy for recurrent superficial bladder carcinoma.

MATERIALS AND METHODS

A total of 236 patients with frequently recurrent stage Ta or T1 bladder tumors were enrolled in our prospective, randomized, multicenter Finnbladder IV study. The initial mitomycin C instillation was instilled in all patients perioperatively after transurethral resection, followed by 4 weekly instillations of mitomycin C. Thereafter patients were randomized to receive monthly for up to 1 year BCG only or interferon-alpha2b and BCG alternating monthly. Primary end points were time to initial recurrence, recurrence rate (number of recurrences per patient-year) and recurrence index (number of recurrent tumors per patient-year).

RESULTS

Of the 236 randomized patients 205 were eligible for study with a median overall followup of 30.7 months. Monthly BCG was superior to alternating monthly interferon-alpha and/or BCG with respect to time to initial recurrence (log rank test p <0.00001) as well as recurrence rate (0.4 versus 0.9, p <0.00001) and index (0.9 versus 3.0, p <0.00001). Side effects were limited.

CONCLUSIONS

Monthly BCG given for up to 1 year preceded by perioperative and an additional 4 weekly mitomycin C instillations is a well tolerated mode of instillation therapy, providing excellent tumor control comparable to that of the best reported instillation regimens. No benefit was obtained by alternating interferon-alpha2b with BCG.

Influence of hydroxychloroquine on the bioavailability of oral metoprolol

AIMS

Hydroxychloroquine (HCQ) is used widely in the treatment of chronic inflammatory diseases such as rheumatoid arthritis. Since there is great interindividual variability in the pharmacokinetics of HCQ and chloroquine is a potent inhibitor of CYP2D6-catalysed pathways in vitro, we wished to study the interaction of HCQ with CYP2D6-mediated metabolism of other drugs in vivo.

METHODS

Metoprolol and dextromethorphan (DM) were selected as probe drugs because they are well-studied and widely used test substrates of CYP2D6. In this randomized, double-blind crossover study, seven healthy volunteers with extensive metabolizer phenotype for CYP2D6 ingested either 400 mg hydroxychloroquine or placebo daily for 8 days after which single oral dose pharmacokinetics of metoprolol were investigated. Dextromethorphan metabolic ratio (DM-MR) was also determined at baseline and after the ingestion of HCQ or placebo.

RESULTS

Concomitant administration of HCQ increased the bioavailability of metoprolol, as indicated by significant increases in the area under the plasma concentration-time curve (65 +/- 4.6%) and maximal plasma concentrations (72 +/- 6.9%) of metoprolol. While the DM-MR values were not significantly changed, the phenotypic classification of one individual, who was heterozygous for a mutant CYP2D6 allele, was converted to a poor metabolizer by HCQ administration.

CONCLUSIONS

HCQ inhibits metoprolol metabolism most probably by inhibiting its biotransformation by CYP2D6. The inhibitory effect of HCQ on dextromethorphan metabolism was not apparent when DM-MR was used as an indicator, except in an individual with limited CYP2D6 capacity.

Basic auditory dysfunction in dyslexia as demonstrated by brain activity measurements

Although the generality of dyslexia and its devastating effects on the individual's life are widely acknowledged, its precursors and associated neural mechanisms are poorly understood. One of the two major competing views maintains that dyslexia is based primarily on a deficit in linguistic processing, whereas the other view suggests a more general processing deficit, one involving the perception of temporal information. Here we present evidence in favor of the latter view by showing that the neural discrimination of temporal information within complex tone patterns fails in dyslexic adults. This failure can be traced to early cortical mechanisms that process auditory information independently of attention.

Receptor subtype-induced targeting and subtype-specific internalization of human alpha(2)-adrenoceptors in PC12 cells

The three alpha(2)-adrenergic receptor subtypes have distinct tissue distributions, desensitization properties, and, in some cell types, subtype-specific subcellular localization and trafficking properties. The subtypes also differ in their neuronal physiology. Therefore, we have investigated the localization and targeting of human alpha(2)-adrenoceptors (alpha(2)-AR) in PC12 cells, which were transfected to express the alpha(2)-AR subtypes A, B, and C. Inspection of the receptors by indirect immunofluorescence and confocal microscopy showed that alpha(2A)-AR were mainly targeted to the tips of the neurites, alpha(2B)-AR were evenly distributed in the plasma membrane, and alpha(2C)-AR were mostly located in an intracellular perinuclear compartment. After agonist treatment, alpha(2A)- and alpha(2B)-AR were internalized into partly overlapping populations of intracellular vesicles. Receptor subtype-specific changes in PC12 cell morphology were also discovered: expression of alpha(2A)-AR, but not of alpha(2B)- or alpha(2C)-AR, induced differentiation-like changes in cells not treated with NGF. Also alpha(2B)-AR were targeted to the tips of neurites when they were coexpressed in the same cells with alpha(2A)-AR, indicating that the targeting of receptors to the tips of neurites is a consequence of a change in PC12 cell membrane protein trafficking that the alpha(2A)-subtype induces. The marked agonist-induced internalization of alpha(2A)-AR observed in both nondifferentiated and differentiated PC12 cells contrasts with earlier results from non-neuronal cells and points out the importance of the cellular environment for receptor endocytosis and trafficking. The targeting of alpha(2A)-AR to nerve terminals in PC12 cells is in line with the putative physiological role of this receptor subtype as a presynaptic autoreceptor.

Chloroethylclonidine and 2-aminoethyl methanethiosulfonate recognize two different conformations of the human alpha(2A)-adrenergic receptor

The substituted cysteine-accessibility method and two sulfhydryl-specific reagents, the methane-thiosulfonate derivative 2-aminoethyl methanethiosulfonate (MTSEA) and the alpha(2)-adrenergic receptor (alpha(2)-AR) agonist chloroethylclonidine (CEC), were used to determine the relative accessibility of engineered cysteines in the fifth transmembrane domain of the human alpha(2A)-AR (Halpha2A). The second-order rate constants for the reaction of the receptor with MTSEA and CEC were determined with the wild type Halpha2A (cysteine at position 201) and receptor mutants containing accessible cysteines at other positions within the binding-site crevice (positions 197, 200, and 204). The rate of reaction of CEC was similar to that of MTSEA at residues Cys-197, Cys-201, and Cys-204. The rate of reaction of CEC with Cys-200, however, was more than 5 times that of MTSEA, suggesting that these compounds may interact with two different receptor conformations. MTSEA, having no recognition specificity for the receptor, likely reacts with the predominant inactive receptor conformation (R), whereas the agonist CEC may stabilize and react preferentially with the active receptor conformation (R*). This hypothesis was consistent with three-dimensional receptor-ligand models, which further suggest that alpha(2A)-AR activation may involve the clockwise rotation of transmembrane domain 5.

Timing of peak serum cortisol values in preterm infants in low-dose and the standard ACTH tests

The low-dose ACTH test seems to reveal mild cases of adrenal insufficiency and is beginning to be preferred over the standard ACTH test in the evaluation of adrenal suppression both in infants and in adults. The concentration-time profile of plasma cortisol in infants after a low ACTH dose is obscure. In this crossover study, we compared timing of the peak values in the low-dose and the standard ACTH stimulation tests in preterm and full-term infants. We performed the standard ACTH tests (250 microg/1.73 m2) and the low-dose ACTH tests (1 microg/1.73 m2) on 10 infants (26-40 wk gestational age) and measured serum cortisol concentration at 0, 30, 40, 60, and 120 min by RIA. Nine of the infants had received postnatal glucocorticoid treatment, and most of them had also been treated with dexamethasone antenatally. In the low-dose test, the peak values occurred at 30 or 40 min in 9/10 patients. In the standard-dose test, the peak values occurred at 60 or 120 min in 8/10 patients. These results are comparable with those from adults. According to this study, blood samples for the low-dose ACTH test in infants should be taken before dosing and between 30 and 40 min after dosing.

Antenatal dexamethasone treatment decreases plasma catecholamine levels in preterm infants

Antenatal corticosteroid therapy (ACT) has many beneficial effects on preterm infants. The cellular mechanisms of action of ACT include beta-adrenergic receptor-mediated cAMP generation. This study investigated the effects of ACT on sympathoadrenal mechanisms during immediate postnatal adaptation of preterm infants. Plasma epinephrine, norepinephrine, 3,4-dihydroxyphenylglycol, and cAMP were measured within 12 h after birth in 103 preterm infants (gestational age 24-36 wk), who were divided into two groups (non-ACT and ACT group) according to whether the mother had received dexamethasone treatment. Infants in the ACT group had significantly lower concentrations of plasma catecholamines than infants in the non-ACT group; plasma epinephrine was 38% lower, and plasma norepinephrine was 20-40% lower in the ACT group, depending on gestational age (r = -0.37 in the non-ACT group and r = -0.28 in the ACT group, p < 0.05). Plasma cAMP concentrations were similar in the two groups. Antihypertensive treatment of the mother was associated with low plasma cAMP (p < 0.001), whereas tocolytic treatment was associated with high plasma cAMP (p = 0.001) of the infant. The results indicate that ACT attenuates the birth-related increase in plasma catecholamines. Still, plasma cAMP levels remain high, which suggests enhanced beta-adrenoceptor signaling after ACT.

Transurethral prostatectomy in patients with preoperative bacteriuria: double-blind study with oral fleroxacin and cefalexin

We compared oral fleroxacin and cefalexin in the prevention of postoperative infectious complications after transurethral prostatectomy (TURP) in patients with preoperative bacteriuria. 95 patients underwent TURP due to benign prostatic hyperplasia with preoperative bacteriuria. The therapy consisted of 7 days of oral fleroxacin 400 mg once a day or cefalexin 500 mg three times daily. After 2 weeks, 62% of the urine samples were sterile in the fleroxacin groups but only 37% in the cefalexin group (p = 0.047). Patients in the cefalexin group had also statistically significantly more symptoms of urinary tract infections. After 6 weeks, the bacterial eradication rate was 53% in the fleroxacin group and 37% in the cefalexin group. There were no septicemias. TURP can be performed with reasonable safety with this oral antibiotic therapy.

Subtype-specific intracellular trafficking of alpha2-adrenergic receptors

The three alpha2-adrenergic receptor subtypes (alpha2a, alpha2b, and alpha2c) are highly homologous G protein-coupled receptors. These receptors all couple to pertussis toxin-sensitive G proteins and have relatively similar pharmacological properties. To further explore functional differences between these receptors, we used immunocytochemical techniques to compare the ability of the three alpha2-receptor subtypes to undergo agonist-mediated internalization. The alpha2a-receptor does not internalize after agonist treatment. In contrast, we observed that the alpha2b-receptor is able to undergo agonist-induced internalization and seems to follow the same endosomal pathway used by the beta2-adrenergic receptor. Attempts to examine internalization of the alpha2c-receptor were complicated by the fact that the majority of the alpha2c receptor resides in the endoplasmic reticulum and cis/media Golgi and there is relatively little cell surface localization. Nevertheless, we were able to detect some internalization of the alpha2c-receptor after prolonged agonist treatment. However, we observed no significant movement of alpha2c-receptor from the intracellular pool to the plasma membrane during a 4-hr treatment of cells with cycloheximide, suggesting that these cells are unable to process alpha2c-receptors in the same way they process the alpha2a or alpha2b subtypes.

Subtype specific recognition of human alpha2C2 adrenergic receptor using monoclonal antibodies against the third intracellular loop

Monoclonal antibodies (Mabs) against human alpha2C2-adrenergic receptor (alpha2C2-AR) were raised in mice and characterized. Bacterially expressed fusion protein consisting a sequence from the putative third intracellular loop (amino acids 213-343) of human alpha2C2 and glutathione-S-transferase (GST) was used as antigen. Results from mass spectrometry of purified thrombin cleaved alpha2C2 polypeptide suggested that the epitope region would lie near the aminoterminal end of the 3rd intracellular loop of human alpha2C2-AR. Elevation of Mabs was detected with Western blotting from mouse blood samples. Three alpha2C2 specific cell clones were expanded to in vitro production in hollow fiber systems. The specificity of the Mabs was further determined by immunoprecipitation and immunocytochemistry. Scatchard analysis of thrombin digested, purified, Europium-labelled antigen (amino acids 213-343 of alpha2C2) revealed binding affinity constants of 0.4 x 10(9), 0.7 x 10(9) and 1.6 x 10(9) M(-1) and Kds of 2.6, 1.4 and 0.6 nM for the three Mabs 2B1, 3G3 and 7G1, respectively.

Specific hybridization probes for mouse alpha 2(IX) and alpha 1(X) collagen mRNAs

We have used polymerase chain reaction (PCR) technology and available cross-species sequence information to construct cDNA probes for mouse alpha 2(IX) and alpha 1(X) collagen transcripts. Sequencing confirmed the identification of the clones. Northern analysis proved sufficient divergence of the cloned sequences from other collagen transcripts: specific detection of the mouse 2.9 kb alpha 2(IX) and 3.3 kb alpha 1(X) collagen mRNAs was seen under normal hybridization and washing conditions.

Debrisoquine oxidation in Parkinson's disease

Variations in the activities of xenobiotic metabolizing liver enzymes may be involved in the pathophysiology of diseases, including Parkinson's disease. We therefore studied the activity of the debrisoquine metabolizing enzyme in 97 patients with newly diagnosed Parkinson's disease. The urine debrisoquine metabolic ratios (MR) of the patients were compared with a group of 176 healthy subjects. There were 4 poor metabolizers (4.1%) among the parkinsonians. This proportion did not differ from that found in the group of healthy subjects (51%). In contrast to earlier finding, the parkinsonian poor metabolizers (PM) had the onset of the disease later than the parkinsonian extensive metabolizers (EM). In the parkinsonian patients, it was observed that the excretion of debrisoquine and 4-OH-debrisoquine into urine correlated inversely with the actual age and age at disease onset. Our results indicate that in patients with Parkinson's disease, debrisoquine hydroxylation is comparable with healthy subjects.

Debrisoquine hydroxylation polymorphism in diabetic patients

Debrisoquine hydroxylation was assessed in 54 type I and in 42 type II diabetic patients. The distribution of metabolic ratio debrisoquine/4-hydroxydebrisoquine (MR) in urine of the patients was compared with a MR-distribution of 176 healthy subjects, and the correlation of glucose balance parameters with the MR was investigated. One poor metabolizer of debrisoquine was found among type I diabetics but no poor metabolizers were found among type II diabetics. Despite the low frequency of the poor metabolizers, the prevalences of debrisoquine hydroxylation phenotypes did not differ from that in healthy volunteers in either diabetic group. No correlation was found between MR and fasting blood glucose or blood glycosylated hemoglobin A1c, whereas a negative correlation was evident between age and the excretion of 4-hydroxydebrisoquine in urine. In summary, debrisoquine hydroxylation is essentially unaltered in type I and type II diabetes mellitus, and no relationship exists between debrisoquine hydroxylation and glucose balance.

The effects of beta-adrenoceptor antagonists and levomepromazine on the metabolic ratio of debrisoquine

The in vivo inhibitory effect of five beta-adrenoceptor antagonists and levomepromazine on debrisoquine metabolism was assessed in 37 subjects. The debrisoquine phenotyping test was performed before and after 7 days' treatment with oxprenolol (40 mg three times daily), propranolol (20 mg three times daily), timolol (10 mg twice daily), pindolol (5 mg twice daily), metoprolol (50 mg twice daily) or levomepromazine (10 mg daily), each of which was given to six-seven subjects. No clear change in the urinary metabolic ratio of debrisoquine/4-OH-debrisoquine (MR) was seen with any of the single beta-adrenoceptor antagonist treatments, but the MR value increased significantly when all beta-adrenoceptor blocker treatments were considered together. Debrisoquine metabolism was clearly impaired after levomepromazine 10 mg daily for 7 days; the mean MR increased from 1.24 +/- 1.6 to 4.70 +/- 5.23 (P = 0.018) and the excretion of 4-hydroxydebrisoquine decreased from 0.92 +/- 0.46 mg to 0.31 +/- 0.19 mg (P = 0.043). Thus, levomepromazine changes MRs towards those characteristic of phenotypically poor metabolizers, but beta-adrenoceptor antagonists at the doses examined have only a marginal effect.