Apoptotic and necrotic brain lesions in a fatal case of carbon monoxide poisoning

A 41-year-old man was accidentally exposed to carbon monoxide (CO) gas and found in a state of cardiopulmonary arrest while he took bath. After admission, he was resuscitated and underwent artificial ventilation in a comatose state and died about 19h later. Computed tomography (CT) examination disclosed bilateral low density area in the basal ganglia and the thalamus, a well-known finding in the CO intoxication. Necropsy, histological examination, DNA ladder assay gave the first line of evidence for the presence of apoptosis as well as necrosis in the human case of CO intoxication. TdT-mediated dUTP-biotin nick-end labeling (TUNEL) positive apoptotic cells were more predominant in the CA2 area than in CA1 area. There is general co-relation between the ratio of TUNEL-positive cells and the DNA laddering on the agarose gel. Basal ganglia and thalamus, which showed bilateral low density area in CT, were revealed to be severe edema. The two types of cell death occurred in the cortex, basal ganglia, hippocampus, thalamus, and cerebellum. Hypoxia caused by CO-hemoglobin formation alone cannot explain the phenomena.

Anti-oxidative properties of fluvastatin, an HMG-CoA reductase inhibitor, contribute to prevention of atherosclerosis in cholesterol-fed rabbits

Studies in vitro reveal that fluvastatin, an HMG-CoA reductase inhibitor, has a strong DPPH radical scavenging activity and achieves concentration-dependent inhibition of copper- and cell-induced oxidation of low-density lipoprotein (LDL). To further examine the anti-oxidative activity of fluvastatin in vivo, we elucidated the effects of chronic treatment with fluvastatin at a dose insufficient to reduce plasma cholesterol levels (2 mg/kg per day) on vasomotion and vascular oxidative stress in thoracic aortas of 0.5% cholesterol-fed rabbits. After 12 weeks of dietary treatment, aortic segments from rabbits fed cholesterol alone showed impaired endothelium-dependent relaxation responses to acetylcholine and A23187 compared to normal chow-fed rabbits in association with a significant increase in plasma total cholesterol levels. In contrast, although plasma total cholesterol levels were not different from those in control cholesterol-fed rabbits, aortic segments from fluvastatin-treated rabbits showed normal relaxation. Compared with rabbits fed cholesterol alone, fluvastatin treatment decreased susceptibility of LDL to ex vivo copper-induced oxidation, reduced vascular superoxide generation, and atheromatous plaque formation. In conclusion, the potent anti-oxidative properties of fluvastatin in addition to its cholesterol-lowering activity appear to contribute to its anti-atherosclerotic effect in vivo.

[L-glutamine-induced heme oxygenase-1 protects small intestine from warm ischemia and reperfusion injury in the rat]

Although it is considered that L-Glutamine (L-Gln) supplementation improves gut morphology and survival in animal models such as radiation and drug-induced enterocolitis, the mechanisms underlying are far from being established. Recently, Gln has been reported to give protection against stress in in vitro intestinal epithelial cell lines through the induction of heat shock proteins (HSPs). This study is designed to examine whether L-Gln may induce cytoprotective molecules such as heme oxygenase-1/HSP32 (HO-1) and reduced glutathione (GSH) in in vivo intestinal tissues, and to clarify whether these molecules may play a role in warm ischemia and reperfusion (I/R) injury. We measured the releases of serotonin and tumor necrosis factor-alpha (TNF-alpha), and graft survival as viability assays following reperfusion of warm ischemically injured intestinal grafts. The substantial expression of HO-1 after L-Gln administration was observed in villous epithelial cells, crypts and muscular layers, and peaked at 6 h, while that of the control group pretreated with lactated Ringer (LR) solution was observed throughout tissues to be slightly similar to those of fresh untreated tissues. Tissue GSH contents slightly increased 24 h after administration and were less reduced through the periods of I/R than those of the LR group. Releases of serotonin and TNF-alpha in L-Gln group were attenuated during the brief periods of warm ischemia, compared with those in the LR group. A significant graft survival rate was also observed between both groups (6/6 of L-Gln group vs. 1/6 of LR group; p < 0.05). In conclusion, the protective effects of L-Gln in small intestines against warm I/R injury were considered to be in part mediated by up-regulation of molecules such as HO-1 and GSH via cellular antioxidant activity. Thus, L-Gln pretreatment may represent an innovative approach to the prevention of complex I/R injury.

Alcohol enhances characteristic releases of dopamine and serotonin in the central nucleus of the amygdala

The amygdaloid complex (AMY) is implicated in emotional and motivational aspects of behavior, including the formation of positive reinforcement association. AMY may also associated with brain rewarding circuitry. In the present study, the effect of ethanol (EtOH) on the release of dopamine (DA) and serotonin (5-HT) was studied in the central amygdaloid nucleus (CeAMY), and projecting excitatory afferents to the ventral tegmental area (VTA), of freely moving Wistar rats by brain microdialysis. Within 20 min of i.p. injection of EtOH (2 g/kg), the levels of DA and 5-HT in the CeAMY dialysate increased over the baseline value by 270 and 160% (N = 6-7), respectively. Addition of EtOH (25, 50 and 100 mM) to the microdialysis perfusion medium for 1 h caused a 115-150% dose-related increase in the extracellular level of DA in the CeAMY. 100 mM EtOH-induced CeAMY DA release continued to increase for 1 h after the perfusion medium was returned to normal perfusion medium. In contrast, the CeAMY 5-HT level was increased only by the addition of 100 mM EtOH for 1 h to 130% for 80 min. The stimulation of the CeAMY by EtOH through the microdialysis membrane showed delayed responses of DA and 5-HT compared with the i.p. injection of EtOH. Overall, the present findings are not sufficient to conclude whether EtOH acts directly or indirectly on the major monoamine nerve cells in the CeAMY, but the degree of acute EtOH action affected the differences in time at the peak response on EtOH-induced DA and 5-HT releases in the CeAMY via VTA.

Inhibitory effects of fluvastatin and its metabolites on hydrogen peroxide-induced oxidative destruction of hemin and low-density lipoprotein

Some 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, which are used as hypolipidemic drugs, have been reported to have the potential to reduce the oxidizability of plasma low-density lipoprotein (LDL) when they are administered in vivo. Their in vivo mechanism is believed to be closely related to their hypolipidemic action based on the HMG-CoA reductase inhibitory activity. We hypothesized that some type of HMG-CoA reductase inhibitor has additional mechanism inhibiting LDL oxidation in vivo due not to its hypolipidemic action but to its direct antioxidative effect based on its unique chemical structure. We directly compared in vitro the antioxidative effects of well-known HMG-CoA reductase inhibitors (fluvastatin, pravastatin, simvastatin, cerivastatin and atorvastatin) on the hydrogen peroxide-induced oxidative destruction of hemin and LDL. Fluvastatin but not the others showed the inhibitory effect on this system. Its effect was dose-dependent and almost as strong as the natural antioxidants, alpha-tocopherol and ascorbic acid. Further, M2, which is a hydroxylated metabolite of fluvastatin, showed stronger antioxidative activity than did fluvastatin. We suggest that among these HMG-CoA reductase inhibitors, fluvastatin especially has an ability to retard the LDL oxidation which is based on not only its hypolipidemic action but also its direct antioxidative effect.

Fluvastatin, an HMG-CoA reductase inhibitor, protects LDL from oxidative modification in hypercholesterolemic rabbits

The antioxidative effect of fluvastatin sodium (fluvastatin) on low-density lipoprotein (LDL) was evaluated in vivo and in vitro. Since ex vivo measurement of the LDL oxidizability is reported to reflect the response of the atherosclerotic process, LDL isolated from rabbits fed a high cholesterol diet for 4 weeks with or without fluvastatin, pravastatin or alpha-tocopherol administration was oxidized by copper ions to estimate conjugated diene formation. Fluvastatin but not pravastatin significantly prolonged the lag time of LDL oxidized by copper ions ex vivo without affecting plasma cholesterol levels at a dose of 3 mg/kg after four weeks of treatment. Alpha-tocopherol-treated rabbits showed dramatically elongated LDL oxidation lag time at a dose of 150 mg/kg. In order to assess the mechanism, the content of alpha-tocopherol, a major endogenous antioxidant in LDL was measured, and we found that only LDL isolated from alpha-tocopherol-treated rabbits contained a significantly larger amount of alpha-tocopherol than that from high cholesterol control rabbits. To elucidate the mechanism further, the effect of fluvastatin on conjugated diene formation during copper-induced LDL oxidation in vitro was studied. Fluvastatin not only prolonged lag time, but also suppressed the rate of LDL oxidation, both in a dose dependent manner above 1 microM, while pravastatin showed no effect. These results suggest the direct antioxidative effect of fluvastatin on LDL oxidation in vivo. Since oxidation of LDL is an important step in the initiation and progression of atherosclerosis, fluvastatin may reduce the risk of this condition not only by lowering plasma cholesterol but also by protecting LDL from oxidation.

Obesity-sleep apnea (Pickwickian) syndrome: autopsy findings and a medicolegal review

A 24-year-old obese woman was found dead in her boyfriend's apartment in his absence. She had been admitted to the hospital six times previously because of diminished consciousness, respiratory failure, and pneumonia. A diagnosis of obesity-sleep apnea (Pickwickian) syndrome was made. An autopsy showed that she had an extremely small larynx, intra-alveolar hemorrhage, edema, pulmonary lymphocyte infiltration, and severe focal myocardial fibrosis. No fresh myocardial lesion, coronary arterial lesion, or findings of heart failure were seen. The woman's elder sister had also died of the same disease at the age of 23. The cause of death was diagnosed as respiratory failure and pneumonia with the sleep-apnea syndrome as the underlying cause of death. Although no autopsy reports of the sleep-apnea syndrome have been published in the field of forensic pathology, this syndrome is a predominant cause of sudden death in obese persons and could be a hidden cause of accidental death in such persons.

Changes in dopamine transporter and c-Fos expression in the nucleus accumbens of alcohol-tolerant rats

BACKGROUND

We have shown that neurochemical functions of 5-HT3 receptors in regulating dopamine (DA) release in the nucleus accumbens (ACC) after alcohol exposure compensate for the dysfunction of serotonergic activity to restore the original properties in processing alcohol tolerance, and that the development of alcohol dependence may be mediated by ACC 5-HT3 receptors. In the present study, the effects of chronic alcohol consumption on the functions of the dopamine transporter (DAT) and the expression of c-Fos proteins were investigated using in vivo brain microdialysis and immunocytochemistry.

METHODS

Perfusion of cocaine and 1-(2-Bis-(4-fluorophenyl) methoxy) ethyl)-4-(3-phenylpropyl) piperizine (GBR 12909) through the microdialysis probe membrane increased the extracellular levels of DA in ACC of alcohol-treated rats that had developed alcohol tolerance by drinking 10% EtOH for 30 days.

RESULTS

The magnitudes of DA reuptake or DAT inhibitors, cocaine, and GBR 12909 that induced DA availability in the ACC were significantly higher in alcohol-treated rats than in controls. When compared with control rats, the alcohol-treated rats exhibited higher levels of DA and its metabolite, DOPAC, in the ACC. Increased expression of the c-Fos-like protein was found in the ACC of alcohol-treated rats. These results show that (1) chronic alcohol consumption desensitizes or decreases the DAT of DA terminals in the ACC and that (2) EtOH causes cellular hyperexcitability of ACC dopaminergic neurons with increased Fos expression during alcohol tolerance.

CONCLUSION

The findings suggested that an abnormality of the dopaminergic neurons in the ACC that are involved with DAT dysfunction is associated with the development of alcohol tolerance.

Superoxide anion scavenging properties of fluvastatin and its metabolites

We investigated the in vitro superoxide anion scavenging activities of fluvastatin and its metabolites. Fluvastatin showed dose-dependent superoxide anion scavenging activity in the NADH/phenazine methosulphate (PMS)/nitroblue tetrazolium (NBT) system, and the effect was as potent as the reference antioxidant, trolox, which is a water-soluble alpha-tocopherol derivative. The superoxide anion scavenging activities of the major metabolites of fluvastatin (M2, M3, M4, M7) were also determined in this system. All of these metabolites showed the activity. In particular, M2 and M3, which possess a phenolic hydroxyl group at the 5 or 6-position of the indole moiety, respectively, showed 3 times stronger activities than that of fluvastatin. Further, we also determined the effects of fluvastatin, M2 and M3 on phorbol myristate acetate (PMA)-induced superoxide anion generation in human peripheral blood polymorphonuclear leukocytes (PMN). The compounds tested also showed a depressing effect on the amount of superoxide anion in this system. We suggest that fluvastatin and its metabolites have the potential to protect cells or lipids from oxidative modification mediated by superoxide anion.

In vitro inhibitory effects of the optical isomers and metabolites of fluvastatin on copper ion-induced LDL oxidation

Fluvastatin is a synthetic hypolipidemic drug which inhibits 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. We compared in vitro the antioxidative effects of two enantiomers (3R, 5S and 3S, 5R) of fluvastatin, which is clinically used as a racemic mixture, on copper ion-induced oxidation of human low-density lipoprotein (LDL). Although 3R,5S-enantiomer of fluvastatin has 30-fold stronger inhibitory activity on HMG-CoA reductase than its optical counterpart, the antioxidative effects of these enantiomers on copper ion-induced LDL oxidation were similar. The antioxidative effects of the metabolites of fluvastatin (M2, M3, M4 and M7) on the copper ion-induced LDL oxidation were also investigated. All the metabolites tested showed an inhibitory effect on this system. Among them, the effects of M2 and M3, which have a phenolic hydroxyl group in each indole moiety, were strong and their potencies were 30-50 times greater than that of fluvastatin. We conclude that not only 3R,5S-enantiomer of fluvastatin but also its optical counterpart and the metabolites also have a potential to show the anti-atherosclerotic effect through their antioxidative activities on lipid peroxidation.

An in vitro study of the hydroxyl radical scavenging property of fluvastatin, and HMG-CoA reductase inhibitor

We investigated the in vitro hydroxyl radical scavenging activity of fluvastatin, a 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitor. Fluvastatin showed hydroxyl radical scavenging activity as potent as that of dimethylthiourea and alpha-tocopherol, which are well-known respectively, as a hydroxyl radical scavenger and a natural antioxidant. Since this effect was not observed in other HMG-CoA reductase inhibitors, such as pravastatin and simvastatin, the scavenging effect of fluvastatin on hydroxyl radicals would not be a common property of HMG-CoA reductase inhibitors, but is derived from the unique chemical structure of fluvastatin. The hydroxyl radical scavenging activities of human metabolites of fluvastatin were also determined. All the tested metabolites possessing the fluorophenyl indole moiety showed activity. Among them, the metabolites which possess a phenolic hydroxyl group on the indole moiety showed stronger effects than that of fluvastatin. We suggest that the fluorophenyl indole moiety of fluvastatin is important for manifestation of the activity and that the phenolic hydroxyl group enhances the potency.

Pharmacokinetics and pharmacological effect of recombinant human granulocyte colony-stimulating factor conjugated to poly(styrene-co-maleic acid) in rats

A new derivative of recombinant human granulocyte colony-stimulating factor (rhG-CSF) has been synthesized by conjugating rhG-CSF to poly(styrene-co-maleic acid) (poly(styrene-co-maleic acid)-rhG-CSF) to try to avoid glomerular filtration and thus potentiate the neutrophil-proliferating activity of rhG-CSF. Poly(styrene-co-maleic acid)-rhG-CSF was highly bound to bovine serum albumin (BSA) and the molecular weight of the poly(styrene-co-maleic acid)-rhG-CSF-BSA complex was estimated to be about 90000 by gel filtration. Intravenous administration of poly(styrene-co-maleic acid)-rhG-CSF to normal rats resulted in a dose-dependent increase in neutrophil count. The neutrophil-proliferating activity of poly(styrene-co-maleic acid)-rhG-CSF was about 10 times greater than that of rhG-CSF. After intravenous injection at a dose of 5 microg protein kg(-1) the total clearance of rhG-CSF fell from 71.0 to 32.1 mLh(-1) kg(-1) following poly(styrene-co-maleic acid) modification. An isolated perfusion study in rat kidney showed that the filtered fraction of rhG-CSF was reduced by conjugation with poly(styrene-co-maleic acid). These results suggest that poly(styrene-co-maleic acid)-conjugation can potentiate the neutrophil-proliferating activity of rhG-CSF by reducing, at least in part, its renal clearance.

Treating neonatal rats with 6-hydroxydopamine induced an increase in voluntary alcohol consumption

Brain dopamine (DA) and serotonin (5-HT) neurotransmission have been implicated in the mediation of alcohol-seeking behavior. We examined the effects of treatment of neonatal rats (3 days after birth) with the neurotoxin 6-hydroxydopamine (6-OHDA; 100 microg/10 microl, intracerebroventricularly) on the relationship between the levels of neurotransmitters and alcohol drinking behavior at the age of 14 weeks. 6-OHDA treatment reduced the levels of DA and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens (ACC), frontal cortex, striatum (STR), tegmentum/substantia nigra, and dorsal raphe nucleus. 5-HT levels in the ACC and STR were increased in the 6-OHDA-treated rats. 6-OHDA-treated rats showed increased alcohol consumption. There was a significant change in the ratio of [5-hydroxyindoleacetic acid]/[5-HT] in the ACC and STR of the treated rats, but no difference in the ratio of [DOPAC]/[DA] between the sham-operated controls and treated rats. 6-OHDA-treated rats had dopaminergic dysfunction in the five brain regions related to the reward system, in part, and a decrease in 5-HT turnover, including the accumulation of 5-HT in the ACC and STR. Furthermore, basal extracellular releases of DA and 5-HT of the ACC were significantly lower in the 6-OHDA-treated rats, compared with the controls. It was suggested that alcohol seeking behavior is associated with the alterations of dopaminergic neurons and the release of 5-HT in the mesocorticolimbic system.

Protective effect of fluvastatin sodium (XU-62-320), a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on oxidative modification of human low-density lipoprotein in vitro

We investigated the protective effect of fluvastatin sodium on the oxidation of low-density lipoprotein (LDL) induced in vitro by copper ions. The extent of lipid peroxidation was assessed by monitoring the increase of UV absorbance at 234 nm, which is the peak absorbance of a conjugated diene. Fluvastatin sodium (1-30 microM) not only prolonged the lag time of oxidation in the initiation step, but also decreased the rate of oxidation in the propagation step, both concentration dependently. Fluvastatin sodium and alpha-tocopherol showed an additive effect when both compounds were added before oxidation. However, when the lag time was prolonged initially by alpha-tocopherol, and fluvastatin sodium and alpha-tocopherol, were further added into the reaction mixture at the end point of the lag phase, fluvastatin sodium still showed an antioxidative effect, whereas alpha-tocopherol showed a pro-oxidative effect. Therefore, the antioxidative property of fluvastatin sodium differs from that of alpha-tocopherol. In this experiment, as neither the double bond-reduced derivative of fluvastatin sodium nor pravastatin sodium showed any protective effect, we concluded that the antioxidative effect of fluvastatin sodium is not a common property of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, but may be derived from its unique chemical structure. Since the oxidative modification of LDL plays an important role in the genesis of atherosclerosis, fluvastatin sodium may help reduce the risk of atherosclerosis, not only by reducing plasma LDL levels but also by protecting LDL from oxidative modification.

Effect of acute renal failure on the disposition of cefoperazone

The effect of acute renal failure on the disposition of cefoperazone was investigated. Rats, 3 days after uranyl nitrate treatment, were used to model acute renal failure. Although plasma-protein binding of cefoperazone decreased significantly in acute renal failure compared with control rats, the plasma clearance of total (bound plus unbound) drug after intravenous administration (50 mg kg(-1)) did not differ significantly between the two groups (5.61+/-2.37 mL min(-1) for control and 4.75+/-2.82 mL min(-1) for acute renal failure). Consequently the plasma clearance of the unbound drug in acute renal failure (6.14+/-1.16 mL min(-1)) was significantly lower than in control rats (15.6+/-3.7 mL min(-1), P < 0.025). Plasma clearance of the drug (both total and unbound) was also dependent on bile flow, and clearance of the unbound drug in acute renal failure rats was lower than in control rats with identical bile flow rates. To examine the mechanism of reduced unbound cefoperazone clearance, an in-vitro experiment using a simultaneous perfusion system of rat liver and kidney was performed. By changing perfusate plasma protein from bovine serum albumin to human serum albumin, the plasma clearance of the total cefoperazone changed to one-sixth in proportion to the unbound cefoperazone in the perfusate plasma. On the other hand, the plasma clearance of the total and unbound drug in acute renal failure rats decreased significantly compared with controls. These results demonstrate that the plasma clearance of unbound cefoperazone, which is mainly eliminated by the liver, decreased in acute renal failure in rats, probably due to changes in hepatic transport.

Discomfort caused by bonded lingual orthodontic appliances in adult patients as examined by retrospective questionnaire

A retrospective questionnaire survey of 111 retention-period adult patients was performed to examine discomfort that may be caused by bonded lingual orthodontic appliances. Despite instructions to avoid or relieve the discomfort, 57% to 76% of patients complained of tongue soreness, difficulty in chewing fibrous food, difficulty in pronouncing the s and t sounds, and difficulty in tooth brushing after the bonding of lingual appliances; the levels were significantly higher than those undergoing edgewise labial treatment. Twenty percent to 44% of patients experienced high levels of the aforementioned discomfort. Although this discomfort decreased gradually with time, 20% to 46% of patients felt discomfort until after the removal of the lingual appliances. The ratio of tongue soreness and speech difficulty caused by upper lingual bracket application to lower lingual bracket application was almost equal. Rank correlation analyses revealed two things: the deeper the bite, the greater the level of tongue soreness, teeth pain and difficulty in chewing tough food; and the larger the overjet, the greater the level of tongue soreness.

Population pharmacokinetics of vancomycin in Japanese pediatric patients

The population pharmacokinetic profile of vancomycin (VCM) in Japanese pediatric patients infected with methicillin-resistant Staphylococcus aureus was analyzed using 181 samples of serum concentration data from 49 patients obtained in routine drug monitoring. The one-compartment linear model was adopted, where the VCM clearance (CL) and the distribution volume (Vd) were correlated with covariates such as postnatal age (AGE) and body weight (BWT). The population pharmacokinetic analysis program NONMEM with the first-order conditional estimation method was used. The results showed that the population mean clearance normalized by BWT increases with AGE up to 1 year of age [CL(L/hour per kg) = 0.1 19 + 0.0619 x (AGE - 1)] and decreases with age over 1 year old [CL(L/hour per kg) = 0.119 + 0.00508 x (1 - AGE)]. The population mean of the distribution volume normalized by BWT was independent of AGE (Vd (L/kg) = 0.522). The interindividual variability of CL was 39.6%, and that of Vd was 18.8%. The intraindividual, residual variability was 34.6%. These results were compared with those in other articles, and a guideline for dosage adjustment in VCM therapy is discussed.

Cryofiltration apheresis for major ABO-incompatible kidney transplantation

The barrier of ABO-incompatible kidney transplantation is the presence of anti-A and anti-B antibodies in the recipient's circulating blood. Double filtration plasmapheresis (DFPP) is usually used to eliminate those antibodies. We tried cryofiltration apheresis (CRYO) in 2 recipients. Patient 1 was a 45-year-old male with B, Rh(+). The titers of IgM anti-A antibody were only reduced from x64 to x32 by the end of 3 sessions of standard CRYO. Renal allografting was not performed. Case 2 was a 29-year-old male with B, Rh(+). CRYO was introduced for 3 sessions. The initial IgM and IgG titers were x128 and negative, respectively. The standard CRYO system was modified by temperature, treated volume, and filter pore size. The IgM anti-A antibody titer was markedly reduced to x2 after the final session of CRYO. The donor was a 56-year-old father with A, Rh(+). Tacrolimus, azathioprine, methylprednisolone, and antilymphocyte globulin were used as the introductory immunosuppression therapy.

Effects of age and ethanol on dopamine and serotonin release in the rat nucleus accumbens

Neural functions in the nucleus accumbens (ACC) play an important role in alcohol drinking behavior. In the present study, we observed the effects of age and ethanol (EtOH) on dopamine (DA) and serotonin (5-HT) release in the ACC of freely moving 4-, 10-, and 16-month-old rats using brain microdialysis techniques. After co-perfusion with 200 mM ethanol, ACC DA, and 5-HT release were decreased significantly in 16-month-old rats compared to those at 4 months old. ACC DA and 5-HT neurons of aged rats were less sensitive to ethanol. On the other hand, both basal extracellular DA and 5-HT release in the ACC were significantly higher in 16-month-old than in 4-month-old rats. Therefore, aging results in opposite changes in basal and alcohol-induced DA and 5-HT release in the ACC.

Quantitative structure-activity analyses of novel hydroxyphenylurea derivatives as antioxidants

A series of substituted hydroxyphenylureas was synthesized, the chemical structure of which was designed based on structures of natural antioxidants, vitamin E (alpha-tocopherol) and uric acid. They exhibited high inhibitory activity against lipid peroxidation. In order to gain an insight into the mechanism of the inhibition reaction, we analyzed their structure-activity relationships quantitatively. Electronic and steric effects of substituents on the phenolic hydroxyl group were shown to be of importance in governing the inhibitory potency. An increase in the electron donating property of substituents toward the phenolic hydroxyl group enhanced the antioxidative activity by the stabilization of an electron-deficient radical-type transition state. The steric shielding by ortho-substituents stabilized the phenoxy radicals formed following the transition state. Derivatives having the carboxyl group were only weakly active presumably because of an intermolecular ion-dipole interaction of the phenolic hydroxyl group with the carboxylate anion which could retard the formation of the transition state.

Population pharmacokinetics of vancomycin in Japanese adult patients

Population pharmacokinetic parameters of vancomycin (VCM) in Japanese adult patients infected with methicillin-resistant Staphylococcus aureus (MRSA) were estimated using 1253 items of serum concentration data from 190 patients obtained in routine drug monitoring. The two-compartment linear model was adopted, and VCM clearance (CL) was correlated with the creatinine clearance (CLcr), which was observed or estimated by the Cockcroft-Gault equation. The population pharmacokinetic analysis program NONMEM with first-order conditional estimation method was used. The results showed VCM clearance to be linearly correlated with CLcr (CL [ml/min] = 0.797 x CLcr) when the estimated CLcr was <85 ml/min, but no linear relationship at higher than this level because of the lack of accuracy in the CLcr estimates. The interindividual variability of CL was 38.5%; K12 and K21 were 0.525 hr(-1) and 0.213 hr(-1), respectively. The distribution volume at steady state (V[SS]) was 60.71, with no significant dependence on the actual body weight. The interindividual variability of Vss was 25.4%. The calculated half-life (t1/2,beta) in a typical patient with CLcr of 85 ml/minute was 12.8 hours. Residual variability was 23.7%. These results were compared to those of healthy volunteers, and guidelines for dosage adjustment in VCM therapy are discussed.

Catecholamine neurons alteration in the brainstem of sudden infant death syndrome victims

BACKGROUND

Sudden infant death syndrome (SIDS) is a leading cause of postneonatal infant death. The pathogenesis of sudden death is still unknown, but an abnormality in the central nervous regulation of breathing during sleep has been suggested.

OBJECTIVE

The aim of study is to confirm the brainstem disorder of SIDS victims. In order to do this, it is necessary to investigate the alterations of brain neurotransmitter systems thought to be involved in respiratory control.

DESIGN

Neuropathologic study performed on the brainstem of SIDS victims.

SUBJECT/METHODS

The disorders of catecholaminergic systems in 22 SIDS victims were examined on the substantia nigra in the midbrain, locus coeruleus in the pons, vagal nuclei, and area reticularis superficialis ventrolateralis with the immunohistochemical method. Immunoperoxidase staining was performed with the antityrosine hydroxylase (TH) and the glial fibrillary acidic protein antibodies. Immunoreactivity was compared with 13 age-matched control infants. For statistical analysis, the chi 2 test and the Student's t test were performed.

RESULTS

The main finding was diminished TH immunoreactivity in the vagal nuclei and area reticularis superficialis ventrolateralis of SIDS victims, suggesting that adrenaline and noradrenaline neurons are altered in SIDS. In addition, this decrease in TH was closely correlated with brainstem gliosis.

CONCLUSION

These catecholaminergic changes may be caused by chronic hypoxia or ischemia, and also may underlie alterations in respiratory and cardiovascular control in sleep.

Cardiovascular effects of 1,5-benzothiazepine derivatives having a l-cis and d-cis configuration in anesthetized dogs

TA-993, a new 1,5-benzothiazepine derivative having a l-cis configuration, has a selective increasing action on limb blood flow, in addition to an antiplatelet aggregating action. The cardiovascular action of TA-993 is quite different from diltiazem, which is a well-known 1,5-benzothiazepine derivative having a d-cis configuration. Therefore, we compared the cardiovascular actions of d-cis and l-cis isomers of TA-993 with those of diltiazem. l-cis-Diltiazem, as well as TA-993, progressively increased femoral, brachial and common carotid blood flow with little change in arterial pressure or vertebral blood flow. However, the peak response to l-cis-diltiazem (20 min after the administration) was observed earlier than that to TA-993 (60 min after the administration). On the other hand, d-cis-TA-993, as well as diltiazem, caused transient hypotension, tachycardia and increases in vertebral, brachial, femoral and common carotid blood flow. Furthermore, their peak effects were observed immediately after the administration. Potency ratios of the vasorelaxing effects of TA-993, l-cis-diltiazem and d-cis-TA-993 to diltiazem in the isolated and K+-contracted canine femoral artery were 0.096, 0.032 and 1.209, respectively. pA2 values for TA-993 and diltiazem against Ca2+-induced contractions in the isolated and K+-depolarized canine saphenous artery were 5.50+/-0.11 and 7.12+/-0.18, respectively. These results indicate that TA-993 shares a common profile with l-cis-diltiazem, and suggest that 1,5-benzothiazepine derivatives of a l-cis configuration are a different class of drug from that of the d-cis configuration.

Inhibitory effect of a new ureidophenol derivative T-2591 on LDL oxidation and ACAT activity

We investigated the effects of T-2591, a new ureidophenol derivative, on low density lipoprotein (LDL) oxidation, acyl CoA: cholesterol acyltransferase (ACAT) and foam cell formation of macrophages in vitro. T-2591 inhibited both copper ion--and endothelial cell--induced LDL oxidation with higher potencies than probucol did. It inhibited ACAT from rabbit intestine, liver and aorta, the respective IC50 values being 0.26, 4.6 and 4.1 microM. It also inhibited ACAT from the mouse macrophage cell line J774 A.1, and its IC50 value (0.067 microM) was much lower than that of CI-976 (4.1 microM). This probably accounts for the inhibition of foam cell formation measured as cholesteryl ester formation in both mouse peritoneal macrophages and J774 A.1 cells at low concentrations (IC50; 0.06 and 0.44 microM, respectively). These observations suggest that T-2591 should be evaluated as a potential tool to retard atherosclerosis in animal models.

Hair analysis for drug abuse. XIV. Identification of substances causing acute poisoning using hair root. I. Methamphetamine

A hair root was evaluated as a specimen for proving acute methamphetamine (MA) poisonings using an animal model and fatal cases of MA intoxicaton. First of all, male pigmented hairy rats (n = 5) were administered with acute poisonous doses (20, 40 and 60 mg/kg) of MA and the hair roots were plucked out with a hair nipper 5 min and 0.5, 1, 2, 6 and 24 h after i.p. injection. The hair root samples were, directly or after washing with detergent, extracted with methanol/5 N HCl (20:1) under vortex mixing at room temperature for 14 h. After evaporation, the residue was derivatized with pentafluoropropionic anhydride and analyzed with GC/MS. From all samples including a 5-min sample, MA was detected at high concentrations (approximately 150 ng/mg) with a small amount of amphetamine (AP). Many animals died within 120 min of administration, but the concentrations in the hair roots increased up to 120 min and then slowly decreased until 24 h. Although MA was definitely detected anytime in the hair roots, almost no MA was found in 24-h plasma. In comparison of the drug levels in hair roots between the washed group and the unwashed group, the levels of the washed group were as a whole 4-5-fold higher than those of the unwashed group. These differences show that most of the drug incorporated into hair root is still not immobilized in the early stage. The ratios of the MA remainder in the washed samples increased with the elapse of time in all cases. However, the slope of the curves definitely dropped after the death of rats, probably due to the stopping of the hair growth and the incorporation of drug into the hair shaft. The ratios of AP/MA after death became a plateau probably due to the stoppage of the activity of metabolism after death, while those before death had increased over time. We analyzed the specimens of hair root of four men who died mainly due to acute poisonings with MA. Consequently, MA in the hair roots was detected at high concentrations, 30.5-134.6 ng/mg, and its metabolic, AP, at the concentrations of 1.2-9.0 ng/mg. Our results suggested that hair root is a good specimen for probing acute MA poisoning.

In-vivo clearance study of vancomycin in rats

The renal handling of vancomycin in rats and the effects of various drugs (probenecid, cimetidine and quinidine) on urinary excretion of the antibiotic were investigated by in-vivo clearance. The vancomycin-to-inulin excretion ratio (ER) was greater than unity at various infusion rates of vancomycin. Quinidine, co-administered with vancomycin, significantly decreased the total, renal and net secretory clearance of the antibiotic. Cimetidine also decreased, though not significantly, the secretory clearance of vancomycin by about 20%, but probenecid did not. These results suggested that vancomycin is secreted in renal tubules in rats, and that quinidine decreases the total clearance of vancomycin partly by inhibiting its tubular secretion in the kidney.

Regulation of p-aminohippurate transport by protein kinase C in OK kidney epithelial cells

We studied the effect of phorbol 12-myristate 13-acetate (PMA), a phorbol ester which activates protein kinase C, on p-aminohippurate (PAH) transport in OK cells. PMA (10(-7) M) almost completely inhibited the transcellular transport of PAH across OK cell monolayers from the basal to the apical side, as well as the accumulation of PAH in the cells. The uptake of PAH across the basolateral membrane of OK cells was inhibited by PMA in a time-and dose-dependent fashion. Exposing the cells with other protein kinase C activators such as active phorbol esters and diacylglycerols also resulted in a significant inhibition of basolateral PAH uptake, but the inactive phorbol ester, 4 alpha-phorbol 12,13-didecanoate, had no effect. The inhibition of basolateral PAH uptake by PMA was blocked by staurosporine, an inhibitor of protein kinase C. Cycloheximide, actinomycin D, colchicine, and cytochalasin D did not affect the inhibitory effect of PMA on basolateral PAH uptake. These results suggested that the PAH transport system in OK cells is under the regulatory control of protein kinase C.

Modulation of organic cation transport and lipid fluidity by benzyl alcohol in rat renal brush-border membranes

PURPOSE

Organic cations are actively transported in renal brush-border membranes (BBM) by the H+/organic cation antiport system. In the present study, we investigated the relationship between membrane fluidity and organic cation transport in the BBM.

METHODS

The effects of benzyl alcohol, a membrane fluidizing agent, on the organic cation tetraethylammonium (TEA) uptake were studied using renal BBM vesicles isolated from rat kidney. BBM fluidity was assessed by fluorescence polarization technique.

RESULTS

H+ gradient-dependent uptake of TEA in BBM vesicles was inhibited by benzyl alcohol in a dose-dependent manner, with an apparent half inhibitory concentration of 18mM. The decrease in fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene in BBM, which represents the increase in membrane fluidity, was correlated with the decrease in TEA transport activity. The dissipation rate of H+ gradient, a driving force for organic cation transport in BBM, was increased by benzyl alcohol. In addition, H+ gradient-independent TEA-TEA exchange was also inhibited by benzyl alcohol. These findings indicate that benzyl alcohol inhibits the uptake of TEA by affecting the intrinsic activity of the organic cation transporter and the H+ gradient dissipation rate.

CONCLUSIONS

The membrane fluidity should be an important determinant for organic cation transport in renal BBM.

Effect of cyclosporin analogues and FK506 on transcellular transport of daunorubicin and vinblastine via P-glycoprotein

PURPOSE

P-glycoprotein-mediated transcellular transport of anticancer agents and the inhibitory effect of cyclosporin analogs and FK506 were investigated.

METHODS

The transcellular transport of daunorubicin and vinblastine by monolayers of LLC-GA5-COL150 cells which overexpressed P-glycoprotein was measured in the presence and absence of cyclosporins or FK506.

RESULTS

Cyclosporins and FK506 inhibited P-glycoprotein-mediated transport of daunorubicin and vinblastine in the order of cyclosporin D, dihydrocyclosporin D > cyclosporin A > FK506 > cyclosporin C, dihydrocyclosporin C. The intracellular accumulation of the anticancer agents was highly associated with the transporting function of P-glycoprotein. The inhibitory effect of cyclosporin D was concentration-dependent. The inhibitory effect of the modulators on P-glycoprotein was not correlated with the immunosuppressive activity, but was correlated with their lipophilicity.

CONCLUSIONS

In the transcellular transport system, lipophilicity may be one of the determinants for the inhibitory effect of various multidrug resistance modulators on the P-glycoprotein-mediated transport.

[Efficacy of intra-arterial chemotherapy with reservoir for patients with unresectable hepatocellular carcinoma]

Long-term results of intra-arterial chemotherapy using a reservoir (IA) for patients with unresectable hepatocellular carcinoma (HCC) were investigated. Ninety-nine patients with unresectable HCC who were treated in our department during the past 7 years were enrolled in this study. Thirty-four out of the 99 patients were treated by IA with a conventional reservoir (SR group), and 21 by IA with a double-lumen reservoir (DR group) by which IA with occlusion of hepatic arterial flow would be possible. The other 44 patients were treated by transcatheter arterial embolization (TAE group). Cumulative 1-and 2-year survival rates were 54.2 and 21.7% in DR group, respectively, and 50.8 and 35.2% in TAE group, respectively. The results of these two groups were statistically equivalent, and were more favorable than those of the SR group. Cumulative patency rate of reservoirs was maintained at 93.7% after one year and at 61.8% after two years. No difference was recognized in this rate according to the type of reservoir. We concluded that IA with a double-lumen reservoir should be taken into consideration as one of the strategies for treatment of unresectable HCC. However, maintenance of catheter-patency would be necessary for satisfactory outcome.

Transport of levofloxacin in a kidney epithelial cell line, LLC-PK1: interaction with organic cation transporters in apical and basolateral membranes

The interactions of levofloxacin, a pyridonecarboxylic acid antibacterial drug, with the organic cation transport systems expressed in a pig kidney epithelial cell line, LLC-PK1, were examined. The transcellular transport of tetraethylammonium was remarkably inhibited by levofloxacin, accompanied by a marked increase in the cellular accumulation of tetraethylammonium in the LLC-PK1, monolayers grown on collagen-coated membrane filters. The results obtained by efflux and uptake of tetraethylammonium revealed that levofloxacin drastically inhibited the apical transport activity rather than the basolateral uptake of tetraethylammonium. Under conditions in which the apical efflux of tetraethylammonium was blocked by pretreatment with p-chloromercuribenzene sulfonate, levofloxacin showed a moderate inhibitory effect against the basolateral uptake of tetraethylammonium. Transepithelial flux of levofloxacin from the basolateral side to the apical side was much greater than the flux in the opposite direction. The flux of levofloxacin was influenced by the apical side pH, resulting in a decreased cellular accumulation by lowering pH. The basal-to-apical transport and cellular accumulation of levofloxacin were not inhibited by either tetraethylammonium or cimetidine. These results suggested that levofloxacin interacts with the apical H+/organic cation antiport system to a greater extent than with the basolateral system. However, transcellular transport of levofloxacin would be mediated by the transport systems which are distinct from the systems for tetraethylammonium in LLC-PK1 cells.

Population pharmacokinetics of phenytoin in Japanese patients with epilepsy: analysis with a dose-dependent clearance model

The population pharmacokinetic parameters of phenytoin were estimated using routine therapeutic drug monitoring data from 116 epileptic patients. The 531 serum concentration values at steady-state after repetitive oral administration were analyzed using a nonlinear mixed effects model (NONMEM) program designed for estimation of population pharmacokinetic parameters. A one-compartment model with dose-dependent clearance was used for the pharmacokinetic analysis of phenytoin. The volume of distribution (V) was estimated to be 1.231/kg in a typical 42-kg patient, assuming that the bioavailability of orally administered phenytoin is 100%. The maximal elimination rate (V(max)) and the Michaelis-Menten constant (K(m)) were 9.80 mg/d/kg and 9.19 micrograms/ml, respectively. The parameter of power function of weight to adjust V and V(max) was estimated to be 0.463. In addition, K(m) for phenytoin appeared to be 16% increased in patients receiving zonisamide concurrently. The population pharmacokinetic parameters of phenytoin will be useful for designing dosage regimens in epileptic patients.

Cepharanthin, a multidrug resistant modifier, is a substrate for P-glycoprotein

P-glycoprotein modulators are respected to be multidrug resistance reversing agents in cancer chemotherapy. Some calcium channel blockers, calmodulin inhibitors or immunosuppressive agents have been used in clinical studies, although the dose of these drugs required to test in vitro experimental data might cause potent pharmacological effects which are not desirable in patients. By using LLC-GA5-COL150 cells that express P-glycoprotein specifically on the apical membranes, we examined the transport of anticancer drugs mediated by P-glycoprotein. Cepharanthin, a biscoclaurine alkaloid, potently inhibits the transport of vinblastine and daunorubicin, both commonly used anticancer agents. The 50% inhibitory concentration of cepharanthin on daunorubicin transport was 2.06 microM. Combined inhibitory effects on daunorubicin transport were observed when cepharanthin was used together with cyclosporin A, a potent immunosuppressive agent and P-glycoprotein modulator. Cepharanthin itself was transported by P-glycoprotein. Transcellular transport of cepharanthin across LLC-GA5-COL150 cell monolayers was saturable when its concentration was under 5 microM, and the transport was inhibited by P-glycoprotein modulators. These results indicate that cepharanthin can reverse multidrug resistance, and proper combination with other P-glycoprotein modulators could potentiate its inhibitory effect on expelling the anticancer drugs out of the cell via P-glycoprotein.

Specificity of p-aminohippurate transport system in the OK kidney epithelial cell line

Substrate specificity of the p-aminohippurate (PAH) transport system was investigated in the OK kidney epithelial cells. PAH uptake by OK cells from the basal side was inhibited by beta-lactam antibiotics such as benzylpenicillin (PCG) and cefazolin. The inhibition of PAH uptake by PCG was competitive and the Ki value was calculated as 108.8 microM. Transcellular transport of PCG across OK cell monolayers occurred unidirectionally from the basal to apical side, and transcellular transport and basolateral uptake were inhibited by PAH, probenecid and beta-lactam antibiotics. The basolateral uptake of cefazolin and cefotiam was also inhibited by PAH and probenecid. The basolateral uptake of PAH and PCG were not affected by aliphatic dicarboxylates with 3 or 4 carbon atoms, but were strongly inhibited by those with 5 or 6 carbon atoms. The inhibitory effect became weaker for a longer dicarboxylate with 7 carbon atoms, then increased again with increasing number of carbon atoms. Such a pattern of inhibition by dicarboxylates is essentially the same with that observed in rat renal proximal tubules in situ. These findings suggest that the PAH transport system in OK cells has a substrate specificity similar to that in rat renal proximal tubules, which is involved in the active secretion of various organic anions including drugs.

Simulation for population analysis of Michaelis-Menten elimination kinetics

A simulation study was conducted to compare the cost and performance of various models for population analysis of the steady state pharmacokinetic data arising from a one-compartment model with Michaelis-Menten elimination. The usual Michaelis-Menten model (MM) and its variants provide no estimate of the volume of distribution, and generally give poor estimates of the maximal elimination rate and the Michaelis-Menten constant. The exact solution to the Michaelis-Menten differential equation (TRUE) requires a precise analysis method designed for estimation of population pharmacokinetic parameters (the first-order conditional estimation method) and also considerable computational time to estimate population mean parameters accurately. The one-compartment model with dose-dependent clearance (DDCL), in conjunction with the first-order conditional estimation or Laplacian method, ran approximately 20-fold faster than TRUE and gave accurate population mean parameters for a drug having a long biological half-life relative to the dosing interval. These findings suggest that the well-known MM and its variants should be used carefully for the analysis of blood concentrations of a drug with Michaelis-Menten elimination kinetics, and that TRUE, in conjunction with a precise analysis method, should be considered for estimating population pharmacokinetic parameters. In addition, DDCL is a promising alternative to TRUE with respect to computation time, when the dosing interval is short relative to the biological half-life of a drug.

Transport of oral cephalosporins by the H+/dipeptide cotransporter and distribution of the transport activity in isolated rabbit intestinal epithelial cells

Transport of cephalosporins was studied using isolated rabbit intestinal epithelial cells. Cephradine uptake by the cells was concentrative and was inhibited by the addition of glycylsarcosine. The accumulated cephradine was effluxed from the cells by the addition of a protonophore, carbonyl cyanide 4-trifluoromethoxyphenylhydrazone (FCCP). Amiloride, an inhibitor of the Na+/H+ exchanger, reduced the steady-state uptake of cephradine, suggesting that the exchanger contributes to the maintenance of an inward H+ gradient as a driving force. Cephradine uptake by ATP-depleted intestinal cells was actively driven by the inward H+ gradient and was inhibited by FCCP and glycylsarcosine. The distribution of cephradine transport activity along the small intestine and villus-crypt axis was also examined in the isolated cells, and the transport activity was higher in the upper parts of the intestinal segments and in villus cells. These results indicate that the uptake of oral cephalosporins by intestinal epithelial cells in concentrative and reversible and that the H+/dipeptide cotransporter and the Na+/H+ exchanger play an important role for the active uptake of these drugs. The activity of the H+/dipeptide cotransporter should be higher in upper segments and in villus cells of the small intestine.

Natriuretic peptide-potentiating actions of neutral endopeptidase inhibition in rats with experimental heart failure

We developed a rat model of heart failure induced by myocardial infarction (MI) which preserves responsiveness to exogenously administered natriuretic peptide, and investigated the potentiating action of neutral endopeptidase (NEP) inhibition on the renal response to endogenous natriuretic peptide in MI rats, comparing with that in the established cardiac-failing model with arterio-venous fistula (AVF). The endogenous plasma concentration of alpha-rat atrial natriuretic peptide (alpha-rANP) in the MI rat was 6.4-fold higher than that in the normal rat, and intravenous infusion of phosphoramidon (165 nmol/min/kg), an NEP inhibitor, induced larger increases in circulating alpha-rANP levels and natriuresis in MI rats than in normal controls. The maximal natriuretic effect of phosphoramidon (165 nmol/min/kg) was equal to that of exogenously administered alpha-rANP (100 pmol/min/kg) in MI rats, whereas plasma alpha-rANP concentration under NEP inhibition was much lower than that after administration of alpha-rANP. The endogenous alpha-rANP levels in AVF rats were as high as those in MI rats. However, the natriuretic effect of phosphoramidon was less in AVF rats than in MI rats, which was consistent with the decreased natriuretic activity observed with administration of exogenous to alpha-rANP in the AVF rat. These results indicate that the natriuretic effect of NEP inhibition is dependent on elevated endogenous alpha-rANP levels in cardiac-failing rats, but cannot be accounted for simply in terms of the increase in circulating alpha-rANP levels. Endogenous natriuretic peptide-mediated natriuresis under NEP inhibition also appears to correlate with the responsiveness to the exogenously administered peptide.

Functional evidence for an apical ANP receptor in LLC-PK1 kidney epithelial cells

The localization of natriuretic peptide receptors was studied in LLC-PK1 cell monolayers grown on a micro-porous membrane filter. The addition of alpha-human atrial natriuretic peptide (alpha-hANP) to the apical side of the cells produced a concentration-dependent increase in cyclic GMP (cGMP) formation, the extent of which was similar to that produced by the addition to the basolateral side. More cGMP was formed with alpha-hANP (1 and 100 nM) than with the C-type natriuretic peptide (100 nM). These findings indicate that the biologically active receptors with high efficacy for alpha-hANP are expressed in both the apical and basolateral membranes in LLC-PK1 cells.

Cyclic RGD peptide inhibits alpha 4 beta 1 interaction with connecting segment 1 and vascular cell adhesion molecule

The integrin supergene family includes receptors for a variety of extracellular matrix as well as cell surface proteins. Integrin alpha 4 has been shown to play an important role in leukocyte adhesion and extravasation during immune and inflammatory reactions. One recognition sequence known to interact with alpha 4 is the Leu-Asp-Val (LDV) site contained in the connecting segment 1 region of fibronectin. Here we present evidence that shows that a conformationally restricted RGD-containing peptide is a potent inhibitor of cell adhesion mediated by alpha 4 beta 1, a receptor not convincingly documented to interact with RGD peptides. This peptide, 1-adamantaneacetyl-Cys-Gly-Arg-Gly-Asp-Ser-Pro-Cys (disulfide bridge between residues 1-8), blocks Jurkat cell adhesion to connecting segment 1-containing peptides as well as cell adhesion to cytokine-activated endothelial cells. Adhesion of Jurkat cells to either vascular cell adhesion molecule-expressing cells or recombinant vascular cell adhesion molecule-coated plates was likewise inhibited by this peptide. Furthermore, alpha 4 beta 1 can bind directly to a cyclic RGD peptide immobilized to Sepharose. Integrins, alpha 5 beta 1, alpha v beta 3, alpha IIb/beta IIIa, alpha 2 beta 1, alpha v beta 1, alpha v beta 5, alpha v beta 6, and alpha 3 beta 1, have been shown to recognize the Arg-Gly-Asp (RGD) sequence present in a variety of extracellular matrix proteins, and our data support the addition of alpha 4 beta 1 to this group. Further studies using molecular modeling of such cyclic RGD peptides could help in the design of more potent peptides or nonpeptide mimetics that could effectively block alpha 4-mediated activity and have potential application in a number of inflammatory diseases.

Differential sensitivity of organic anion transporters in rat renal brush-border membrane to diethyl pyrocarbonate

The effect of various chemical modifiers on p-aminohippurate (PAH) uptake by a potential-sensitive system and by an anion exchanger was studied in rat renal brush-border membrane vesicles. Among various chemical modifiers, diethyl pyrocarbonate (DEPC) selectively inhibited potential-sensitive PAH uptake but not the uptake by the anion exchanger. The inhibitory effect of DEPC on potential-sensitive PAH uptake was not due to the facilitated dissipation of membrane potential, which was evidenced by the studies with a potential-sensitive fluorescence dye diS-C3(5). The potential-sensitive PAH uptake was inhibited by DEPC in a concentration-dependent manner, and kinetic analysis showed that the decreased uptake of PAH in DEPC-treated vesicles was due to the decrease of Vmax. The inhibition of the PAH uptake was protected by the presence of organic anions during the DEPC treatment. These findings indicate that PAH transport by the potential-sensitive system and by the anion exchanger is mediated by structurally distinct transporters. Amino acid residue(s) modified by DEPC, most likely a histidine residue, should play an important role in the potential-sensitive transport of PAH in rat renal brush-border membrane.

Metastatic epithelioid sarcoma with an N-ras oncogene mutation

At age 25 a Japanese woman noticed an elastic-hard nodule 2 cm in diameter on the anterior side of her right leg. The nodule had developed an ulcer in its center. Simple resection was performed several times. However, the lesion recurred repeatedly. The patient underwent amputation of the right leg at the age of 34, because the diagnosis of epithelioid sarcoma was established histologically. No recurrence was observed for 9 years. Recently, the patient noticed multiple painful, ulcerative nodules about 1 cm in diameter on her scalp, trunk, and extremities. She refused extensive resection for a religious reason and died of massive hematemesis. Autopsy revealed metastatic epithelioid sarcoma in the skin, lungs, kidneys, pancreas, transverse colon, thyroid, and sternum. Chromosomal analysis of the tumor revealed various aberrations and an N-ras oncogene mutation.

Cellular toxicity of aminoglycoside antibiotics in G418-sensitive and -resistant LLC-PK1 cells

The effects of gentamicin and G418 on the cellular function of LLC-PK1 epithelial pig kidney cells were investigated. Exposing the cells for 2 days to these aminoglycoside antibiotics inhibited the increase in cell-associated apical membrane enzyme activity (alkaline phosphatase, aminopeptidase, and gamma-glutamyltransferase). Kinetic analysis revealed that the maximal activity of alkaline phosphatase was reduced by these aminoglycosides. Both aminoglycosides inhibited [3H]leucine incorporation into microsomes prepared from LLC-PK1 cells. The LLC-PK1 cells transfected with DNA encoding aminoglycoside 3'-phosphotransferase II, designated T2000B, were resistant to G418 as assessed by colony formation assay and the number of floating dead cells and by assay of apical enzyme activity. After a 4-hr exposure to G418, [3H]leucine incorporation in the host LLC-PK1 cells was inhibited, whereas that in T2000B cells was relatively unaffected. Gentamicin inhibited [3H]leucine incorporation similarly in both cells. The inhibition of protein synthesis by aminoglycosides occurred earlier than that of apical enzyme activity. These findings suggest that the inhibition of protein synthesis by aminoglycoside antibiotics is a possible cause of the reduction in cell viability as well as the apical enzymes in LLC-PK1 cells.

Simulation for the analysis of distorted pharmacodynamic data

A simulation study was conducted to compare the performance of alternative approaches for analyzing the distorted pharmacodynamic data. The pharmacodynamic data were assumed to be obtained from the natriurertic peptide-type drug, where the diuretic effect arises from the hyperbolic (Emax) dose-response model and is biased by the dose-dependent hypotensive effect. The nonlinear mixed effect model (NONMEM) method enabled assessment of the effects of hemodynamics on the diuretic effects and also quantification of intrinsic diuretic activities, but the standard two-stage (STS) and naive pooled data (NPD) methods did not give accurate estimates. Both the STS and the NONMEM methods performed well for unbiased data arising from a one-compartment model with saturable (Michaelis-Menten) elimination, whereas the NPD method resulted in inaccurate estimates. The findings suggest that nonlinearity and/or bias problems result in poor estimation by NPD and STS analyses and that the NONMEM method is useful for analyzing such nonlinear and distorted pharmacodynamic data.

Bestatin transport in rabbit intestinal brush-border membrane vesicles

The effect of papain treatment on bestatin uptake by rabbit intestinal brush-border membrane vesicles (BBMVs) was studied. Papain treatment of BBMVs effectively diminished aminopeptidase activity but not bestatin uptake by a H+/dipeptide cotransporter. Bestatin uptake by BBMVs was composed of two saturable components, and after papain treatment the high-affinity component disappeared while the low-affinity component was retained. These findings suggest that high- and low-affinity components represent bestatin binding to aminopeptidase and the true uptake by the H+/dipeptide cotransporter, respectively.

Predictive performance of the Bayesian analysis: effects of blood sampling time, population parameters, and pharmacostatistical model

The present paper reports theoretical equations for the predictive performance of the Bayesian forecasting method. The precision of parameter estimates and predicted concentrations for an individual was described by general equations with the aid of a variance-covariance matrix of parameter estimates that involved the Bayes theorem. The equations were applied to assess the predictive performance of the one-point Bayesian method in association with blood sampling time, the population parameters, and the pharmacostatistical model. The simulation study showed that the prediction error in parameter estimates essentially depended upon the sampling time but the magnitude of dependency was affected by the size of inter- and intraindividual variances. With a smaller value of interindividual variance, the dependency on sampling time was less apparent. Effects of sampling time were further examined using clinical data obtained from 20 patients taking theophylline, and the results were in good agreement with the theoretical consideration. The present general equations are useful to investigate the sampling strategy as well as structural and variance modeling on the predictive performance of the Bayesian method.