Physiologically-based pharmacokinetic analysis of grepafloxacin

Grepafloxacin (GPFX) is a synthetic new quinolone antimicrobial agent that possesses an extensive tissue distribution and exhibits a strong antibacterial activity in vivo. In this study, the tissue distribution characteristics of GPFX were examined using tissue concentration-time profiles following intravenous administration to rats. Subsequently, the pharmacokinetics of GPFX were analyzed based on the physiological pharmacokinetic model. The tissue-to-plasma partition coefficients (Kp) of GPFX in rats were high in all tissues except brain. A pharmacokinetic model for rabbits, monkeys and dogs was constructed using the tissue-to-plasma free concentration ratio (Kp,f) of GPFX in rats to simulate the GPFX concentration-time profile in plasma following intravenous administration of GPFX to each animal. The calculation-derived concentrations correlated well with the experimentally-derived data, suggesting that there are no interspecies differences in the high tissue distribution characteristics of GPFX. The clearance rates of GPFX in humans were predicted from the pharmacokinetic parameters of rats, rabbits, monkeys and dogs by an animal scale-up method and a pharmacokinetic model for humans was constructed. The GPFX concentration-time profiles in plasma, following oral administration of GPFX to humans, were predicted within 0.5-1.0 h of mean absorption time and the calculation-derived results were in good agreement with the experimental data. Thus, it is suggested that the concentration-time profile in plasma and all human organs can be predicted from the pharmacokinetic data of animals.

An aldose redutase inhibitor prevents the intimal thickening in coronary arteries of galactose-fed beagle dogs

AIMS/HYPOTHESIS

Although increased polyol pathway activity has been implicated in the pathogenesis of diabetic microangiopathy, the relation with diabetic macroangiopathy remains unclear. Galactose feeding is known to stimulate the polyol pathway and to develop abnormalities similar to those in diabetic microangiopathy. Our study was conducted to investigate whether an activation of polyol pathway by long-term treatment with galactose produced morphological changes in coronary arteries of dogs and the effect of an aldose reductase inhibitor, epalrestat, was also studied.

METHODS

Dogs received either normal chow or chow containing 30% galactose with or without epalrestat given orally (20 or 50 mg x kg(-1)). After 44 months, morphometric analyses of coronary arteries were carried out and the galactitol contents in aortas were measured.

RESULTS

The ratio of areas of the intimal layer to those of the medial layer, an indicator of intimal thickening, was statistically significantly increased in galactose-fed dogs compared with control dogs. Galactose-fed dogs had a remarkable accumulation of galactitol in their aortas. These morphological and biochemical deficits were reduced by treatment with epalrestat.

CONCLUSION/INTERPRETATION

This report morphologically shows diabetes-like macrovascular abnormalities in galactosaemic animals, suggesting that polyol pathway hyperactivity is closely related to the development of diabetic macroangiopathy, which could be prevented by aldose reductase inhibition.

A protein kinase C-beta-selective inhibitor ameliorates neural dysfunction in streptozotocin-induced diabetic rats

Increased protein kinase C (PKC) activity has been implicated in the pathogenesis of diabetic retinopathy and nephropathy. However, the role of PKC in diabetic neuropathy remains unclear. The present study was conducted to compare the effect of PKC inhibition by a PKC-beta-selective inhibitor, LY333531 (LY), on diabetic nerve dysfunction with that of an aldose reductase inhibitor, NZ-314 (NZ). Streptozotocin-induced diabetic rats were treated with or without LY and/or NZ for 4 weeks, and motor nerve conduction velocity (MNCV), coefficient of variation of R-R interval (CVR-R), sciatic nerve blood flow (SNBF), peak latencies of oscillatory potentials on electroretinogram, PKC activities in membranous and cytosolic fractions of sciatic nerves, and polyol contents in the tail nerves were measured. Untreated diabetic rats demonstrated delayed MNCV, decreased CVR-R, reduced SNBF, and prolonged peak latencies of oscillatory potentials. Treatment with LY as well as NZ prevented all these deficits in diabetic rats. There were no significant differences in PKC activities in membranous or cytosolic fractions of sciatic nerves between normal and diabetic rats. Treatment with neither LY nor NZ altered PKC activities. Nerve myo-inositol depletion in diabetic rats was ameliorated not only by NZ, but also by LY. These observations suggest that inhibition of PKC-beta by LY may have a beneficial effect in preventing the development of diabetic nerve dysfunction, and that this effect may be mediated through its action on the endoneurial micro-vasculature.

An aldose reductase inhibitor prevents the glucose-induced increase in PDGF-beta receptor in cultured rat aortic smooth muscle cells

To examine the role of platelet-derived growth factor (PDGF) and the polyol pathway in the growth activity of smooth muscle cells (SMCs), [(3)H]-thymidine incorporation, [(125)I]-PDGF-BB binding and expression of PDGF-beta receptor protein were measured in rat aortic SMCs cultured with 5.5 or 20 mM glucose with or without anti-PDGF antibody or an aldose reductase inhibitor, epalrestat. SMCs cultured with 20 mM glucose demonstrated an accelerated thymidine incorporation compared with SMCs cultured with 5.5 mM glucose, which was prevented by anti-PDGF antibody. This acceleration of growth activity by 20 mM glucose was accompanied by an increase in PDGF-BB binding, which was due to the increased number of PDGF-beta receptors and the overexpression of PDGF-beta receptor protein. Epalrestat prevented all these abnormalities. These observations suggest that polyol pathway hyperactivity plays an important role in the proliferation of SMCs which may be mediated through the accelerated expression of PDGF-beta receptor protein.

Effect of vitamin E and allylamine on the proliferation of cultured aortic smooth muscle cells from streptozotocin-induced diabetic rats

To investigate the effect of vitamin E on the proliferation activity of vascular smooth muscle cells (SMCs) in diabetes mellitus, [3H]-thymidine incorporation was measured in cultured SMCs isolated from normal and streptozotocin-induced diabetic rats treated with or without vitamin E and/or allylamine. Untreated diabetic rats demonstrated significantly elevated concentrations of serum total cholesterol, triglycerides and malondialdehyde (MDA). Allylamine caused a further increase in serum MDA. Treatment with vitamin E decreased the serum concentrations of triglycerides and MDA in both allylamine-treated and -untreated diabetic rats. [3H]-Thymidine incorporation in cultured SMCs from diabetic rats was significantly increased compared with that from normal rats. SMCs from allylamine-treated diabetic rats showed an enhanced increase in thymidine incorporation compared with that from untreated diabetic rats. The increase in thymidine incorporation in SMCs from untreated and allylamine-treated diabetic rats was significantly reduced by the treatment with vitamin E. These observations suggest that vitamin E has a preventive effect on the proliferation of vascular SMCs in diabetes, and that this effect may be mediated through an enhancement of free radical scavenging.

Polyol pathway hyperactivity is closely related to carnitine deficiency in the pathogenesis of diabetic neuropathy of streptozotocin-diabetic rats

To investigate the relationship between polyol pathway hyperactivity and altered carnitine metabolism in the pathogenesis of diabetic neuropathy, the effects of an aldose reductase inhibitor, [5-(3-thienyl) tetrazol-1-yl]acetic acid (TAT), and a carnitine analog, acetyl-L-carnitine (ALC), on neural functions and biochemistry and hemodynamic factors were compared in streptozotocin-diabetic rats. Significantly delayed motor nerve conduction velocity, decreased R-R interval variation, reduced sciatic nerve blood flow and decreased erythrocyte 2, 3-diphosphoglycerate concentrations in diabetic rats were all ameliorated by treatment with TAT (administered with rat chow containing 0.05% TAT, approximately 50 mg/kg/day) or ALC (by gavage, 300 mg/kg/day) for 4 weeks. Platelet hyperaggregation activity in diabetic rats was diminished by TAT but not by ALC. TAT decreased sorbitol accumulation and prevented not only myo-inositol depletion but also free-carnitine deficiency in diabetic nerves. On the other hand, ALC also increased the myo-inositol as well as the free-carnitine content without affecting the sorbitol content. These observations suggest that there is a close relationship between increased polyol pathway activity and carnitine deficiency in the development of diabetic neuropathy and that an aldose reductase inhibitor, TAT, and a carnitine analog, ALC, have therapeutic potential for the treatment of diabetic neuropathy.

Flow cytometry measurements of subsets of T, B and NK cells in peripheral blood lymphocytes of atomic bomb survivors

Previous studies of blood cells from atomic bomb survivors have shown that frequencies of chromosome aberrations and somatic mutations are elevated in heavily exposed survivors and that T-cell functions and the number of mature T cells are decreased in the survivors who were exposed to radiation as adults. Current progress in flow cytometry allows a sophisticated analysis of various subsets of T, B and NK cells. In the present study, proportions of such subsets in peripheral blood lymphocytes from atomic bomb survivors (159 survivors estimated to be exposed to > or =1.5 Gy) and 252 controls were measured using multiple combinations of monoclonal antibodies to lymphocyte differentiation antigens to investigate whether the previous radiation exposure had altered the composition of the subsets. Among T-cell subsets, the proportion of CD4+ T-cell subsets was decreased significantly in the heavily exposed survivors; this tendency was apparent for the CD4+CD45RA+ naive T-cell subset. However, there were no significant differences in the proportions of CD8+ T-cell subsets between the exposed survivors and controls. As for the B-cell subsets, the proportion of both CD5+ and CD5 B cells as well as CD23+ and CD23- B cells increased in the heavily exposed survivors. Further, no effect of radiation was found in the proportion of NK-cell subsets. These results strongly suggest that previous radiation exposure altered the composition of T and B cells in the peripheral blood of atomic bomb survivors, and they raise the possibility that atomic bomb radiation may have affected the developmental processes of T and B cells.

Uptake of basic drugs into rat lung granule fraction in vitro

Although basic drugs are distributed widely in various tissues, they are characteristically concentrated in the lung granule fraction. We examined the uptake of seven lipophilic basic drugs into rat lung granule fraction (P2) in vitro and investigated the contributions of drug lipophilicity and lysosomal trapping to the characteristic lung P2 distribution. The uptake of each drug into P2 was examined at various pH values. The drug concentration in P2 was determined by gas chromatography. Biperiden (BP) was rapidly taken up into P2, reaching a maximal concentration within 1 min at pH 7.4 at both 4 degrees C and 37 degrees C. Both BP and chlorpromazine uptake into P2 was biphasic. Though the uptake rates of the seven drugs into P2 increased with rising pH, the rate of increase varied for each drug. There was a good correlation between the octanol-water partition coefficient of the non-ionized form (P(oct)) of each drug and the uptake into P2 in the presence or absence of NH4Cl, which inhibits lysosomal trapping. However, uptake into P2 in the presence of NH4Cl showed a stronger P(oct)-dependency. We conclude that the distribution of basic drugs into lung P2 is dependent on both drug lipophilicity and lysosomal uptake.

Human T-lymphotropic virus type-I infection, antibody titers and cause-specific mortality among atomic-bomb survivors

There have been few longitudinal studies on the long-term health effects of human T-lymphotropic virus type-I (HTLV-I) infection. The authors performed a cohort study of HTLV-I infection and cause-specific mortality in 3,090 atomic-bomb survivors in Nagasaki, Japan, who were followed from 1985-1987 to 1995. The prevalence of HTLV-I seropositivity in men and women was 99/1,196 (8.3%) and 171/1,894 (9.0%), respectively. During a median follow-up of 8.9 years, 448 deaths occurred. There was one nonfatal case of adult T-cell leukemia/lymphoma (incidence rate = 0.46 cases/1,000 person-years; 95% confidence interval [CI] 0.01-2.6). After adjustment for sex, age and other potential confounders, significantly increased risk among HTLV-I carriers was observed for deaths from all causes (rate ratio [RR] = 1.41), all cancers (RR = 1.64), liver cancer (RR = 3.04), and heart diseases (RR = 2.22). The association of anti-HTLV-I seropositivity with mortality from all non-neoplastic diseases (RR = 1.40) and chronic liver diseases (RR = 5.03) was of borderline significance. Possible confounding by blood transfusions and hepatitis C/B (HCV/HBV) viral infections could not be precluded in this study. However, even after liver cancer and chronic liver diseases were excluded, mortality rate was still increased among HTLV-I carriers (RR = 1.32, 95% CI 0.99-1.78), especially among those with high antibody titers (RR = 1.56, 95% CI 0.99-2.46, P for trend = 0.04). These findings may support the idea that HTLV-I infection exerts adverse effects on mortality from causes other than adult T-cell leukemia/lymphoma. Further studies on confounding by HCV/HBV infections and the interaction between HCV/HBV and HTLV-I may be required to analyze the increased mortality from liver cancer and chronic liver diseases.

Influence of ammonium chloride on the tissue distribution of anticholinergic drugs in rats

Ammonium chloride (NH4Cl) increases lysosomal pH and thereby abolishes intralysosomal accumulation of drugs. Its effect on the tissue distribution of biperiden and trihexyphenidyl in rats has been investigated. The tissue-plasma concentration ratios (Kp) of these drugs in various tissues were determined by infusion studies at steady-state in the presence or absence of NH4Cl. Treatment with NH4Cl reduced the Kp values for both drugs, causing the largest reduction in Kp in the lung (52.1 to 11.8 for biperiden and 59.5 to 18.9 for trihexyphenidyl; ratios of decrease 0.77 and 0.68, respectively), followed by the heart and kidneys, with relatively small reductions in the brain, gut, muscle and fat. Subcellular fractionation studies in the lung indicated that the subcellular fraction-plasma concentration ratio of each drug at the steady state (K(p,sf)) was reduced by treatment with NH4Cl, with the largest decrease in the post-nuclear fraction (ratio of decrease 0.82 for biperiden and 0.74 for trihexyphenidyl), followed by the nucleus, microsomes and supernatant, in that order. A strong correlation was found between the ratio of decrease in K(p,sf) after NH4Cl treatment and the specific activity of acid phosphatases, a marker of lysosomes, in each fraction (biperiden, r = 0.948; trihexyphenidyl, r = 0.945). These results suggest that acidic organelles contribute significantly to the distribution kinetics of anticholinergic drugs.

Synergistic antitumor interaction of human monocyte chemotactant protein-1 gene transfer and modulator for tumor-infiltrating macrophages

PURPOSE

In order to evaluate the possibility of synergistic antitumor gene therapy by the gene delivery of monocyte chemotactant protein-1 (MCP-1/MCAF/IE), the effect of a biological response modulater for macrophages on tumor progression of gene transfected tumor cells was studied.

METHODS

Cachexia-inducing adenocarcinoma cells (cell line colon 26, clone 20) were transfected with either a control plasmid or MCP-1 cDNA.

RESULTS

The production of MCP-1 reached 70-80 ng/ml in vitro when transfectant cells were cultured at a cell density of 1 x 10(5) cells/ml for 3 days. Transfection of MCP-1 cDNA did not affect the growth rate in vitro. Also, MCP-1-transfectants formed tumors after intra-footpad inoculation similar in size to the parental cells. The number of infiltrating macrophages in the primary tumor of the transfectant rapidly increased from the 3rd to 5th day after inoculation as revealed by immunohistochemical staining using an antibody against mouse macrophages. An earlier, greater, but no longer-lasting increase in tumor-infiltrating macrophages was induced in tumors by MCP-1 transfection was compared to that induced by the parent cells. On the 10th day after the inoculation, the tumor-infiltrating macrophages in mice inoculated MCP-1 transfectants were decreased to a level similar to that of the parent cells. Groups of mice were treated intraperitoneally with LPS at different times after the inoculation. Tumor cells producing high levels of MCP-1 were significantly lysed by macrophages treated with LPS, whereas parental or control transfected cells were not. Conclusions. Combination immunotherapy can provide a rationale for the application of MCP-1 treatment to increase immunological responses to cancer.

Intestinal absorption of ursodeoxycholic acid in children and adolescents with inflammatory bowel disease

BACKGROUND

Ursodeoxycholic acid absorption in the proximal intestine may be impaired in patients with inflammatory bowel disease.

METHODS

We examined the intestinal absorption of ursodeoxycholic acid by the oral ursodeoxycholic acid tolerance test in 19 children and adolescents with inflammatory bowel disease at various stages, including 8 patients with unoperated Crohn's disease, 3 patients with ileal-resected Crohn's disease, 8 with ulcerative colitis, and 8 healthy control subjects.

RESULTS

Ursodeoxycholic acid malabsorption was present in all patients with unoperated Crohn's disease in the first diagnosed active stage, in 3 of 5 patients in a relapsing active stage, and in 2 of 8 patients in remission. Ursodeoxycholic acid absorption was significantly lower in patients in the first diagnosed active stage than in the healthy controls (p < 0.01) or in patients in remission (p < 0.01). There was no significant difference between healthy controls and the patients in a relapsing active stage or in remission. Ursodeoxycholic acid absorption was abnormal during the first postoperative month in patients with ileal-resected Crohn's disease, but normalized over time. Malabsorption of ursodeoxycholic acid was not observed in any patients with ulcerative colitis.

CONCLUSIONS

These findings suggest that absorption of ursodeoxycholic acid in the proximal intestine is impaired in patients with Crohn's disease and that the oral ursodeoxycholic acid tolerance test is a convenient and useful means of evaluating the absorption of bile acid in the proximal intestine in pediatric patients with ileal or ileocolic Crohn's disease.

Urinary 7alpha-hydroxy-3-oxochol-4-en-24-oic and 3-oxochola-4,6-dien-24-oic acids in infants with cholestasis

BACKGROUND/AIMS

Urinary 3-oxo-delta4 bile acids have been detected in infants who ultimately died of liver disease. We used qualitative and quantitative methods to compare urinary 3-oxo-delta4 bile acids in liver disease, determining their composition and evaluating the prognostic implication in patients of various ages with various liver diseases.

METHODS

Gas chromatography-mass spectrometry was used to measure 3-oxo-delta4 bile acids in the urine of patients and healthy controls.

RESULTS

Patients with a deficiency of 3-oxo-delta4-steroid 5beta-reductase and acute hepatic failure exhibited a significantly higher percentage of 3-oxo-delta4 bile acids in total bile acids in urine than the healthy controls or other patient groups, including those with neonatal cholestasis or biliary atresia (p<0.0001). The urinary 3-oxo-delta4 bile acids in patients with 3-oxo-delta4-steroid 5beta-reductase deficiency who had a poor prognosis were mainly 7alpha-hydroxy-3-oxochol-4-en-24-oic acid and 3-oxochola-4,6-dien-24-oic acid.

CONCLUSIONS

Our results indicate that an increase in the 7alpha-hydroxy-3-oxochol-4-en-24-oic acid and 3-oxochola-4,6-dien-24-oic acid in the urine of patients with hepatobiliary disease indicates a poor prognosis.

Effect of sequence of administration on the pharmacokinetic interaction between the anticholinergic drug biperiden and [3H]quinuclidinyl benzylate or [3H]N-methylscopolamine in rats

In rats the pharmacokinetic interactions between the anticholinergic drug biperiden and [3H]quinuclidinyl benzylate ([3H]QNB) or [3H]N-methylscopolamine ([3H]NMS) is affected by the sequence in which the drugs are administered. Drug concentrations in various tissues were determined after intravenous administration of [3H]QNB or [3H]NMS (325 ng kg(-1)). Biperiden (6.4 mg kg(-1)) was administered either 5 min before, concomitantly with or 20 min after injection of [3H]QNB or [3H]NMS. When biperiden was administered concomitantly with or before [3H]QNB, distribution of [3H]QNB among the regions of the brain and other tissues was reduced; at 4 h the ratio of the distribution of [3H]QNB for experimental animals to that for control animals ranged from 0.15 to 0.9. When biperiden was administered after [3H]QNB, the distribution of [3H]QNB in the brain and other tissues was significantly higher than for the other two treatments (P < 0.01). However, for [3H]NMS the sequence of administration had no effect on the distribution of the drug in the brain and other tissues except for the kidney. In-vitro, in crude synaptosomal membranes, the amount of [3H]QNB at 2 h relative to the control concentration at equilibrium was 87% when biperiden was added before [3H]QNB and 56% when biperiden was added after [3H]QNB. In both instances the concentration of [3H]NMS reached equilibrium within 30 min. These findings suggest that the difference between the rate constant of association and dissociation at the possible site of action gives rise to the effect of the sequence of administration on the pharmacokinetic interaction.

Characteristic subcellular distribution, in brain, heart and lung, of biperiden, trihexyphenidyl, and (-)-quinuclidinyl benzylate in rats

The subcellular distribution of biperiden (BP), trihexyphenidyl (TP) and (-)-quinuclidinyl benzylate (QNB) in brain, heart and lung following high dose (3.2 mg/kg) i.v. administration was investigated in rats. The subcellular distribution of BP or TP used clinically conformed with that of QNB, a typical potent central muscarinic antagonist. The concentration-time courses of the brain subcellular fractions for these drugs were of two types which decreased slowly and in parallel to the plasma concentration. The subcellular distribution in the brain and heart was dependent on the protein amount of each fraction. The percent post-nuclear fraction (P2) of the total concentration in the lung was characteristically about 3-5 times larger than that in the heart. It was elucidated that the distribution in the lung differs from that in the brain and heart, with high affinity which is not dependent on the protein amount in the P2 fraction containing lysosomes. On the other hand, at a low dose (650 ng/kg) of 3H-QNB, each fraction as a percentage of the total concentration in the brain increased in synaptic membrane and synaptic vesicles and decreased in nuclei and cytosol as compared with the high dose. These results show that although the tissue concentration-time courses of anticholinergic drugs appear to decrease simply in parallel to plasma concentration, the subcellular distribution exhibits a variety of patterns among various tissues.

Electroretinogram in sucrose-fed diabetic rats treated with an aldose reductase inhibitor or an anticoagulant

To investigate the role of increased polyol pathway activity and hemodynamic deficits in the pathogenesis of diabetic retinopathy in non-insulin-dependent diabetes mellitus (NIDDM), Otsuka Long-Evans Tokushima fatty (OLETF) rats, an animal model of human NIDDM, were given water with or without 30% sucrose and some of them were fed laboratory chow containing 0.03% cilostazol, an anticoagulant, or 0.05% [5-(3-thienyl)tetrazol-1-yl] acetic acid monohydrate (TAT), an aldose reductase inhibitor, for 8 wk. Long-Evans Tokushima Otsuka (LETO) rats were used as nondiabetic controls. The peak latencies of oscillatory potentials of the electroretinogram in sucrose-fed OLETF rats were significantly prolonged compared with those in OLETF rats without sucrose feeding and LETO rats. There was a marked increase in platelet aggregability and a significant decrease in erythrocyte 2,3-diphosphoglycerate in sucrose-fed OLETF rats. Cilostazol significantly improved these parameters without changes in retinal levels of sorbitol and fructose. TAT, however, ameliorated all of these parameters. These findings confirm that the sucrose-fed OLETF rat is a useful animal model of retinopathy in human NIDDM and suggest that cilostazol improved diabetic retinopathy by modifying vascular factors, not by altering polyol pathway activity.

Pathology of chronic hepatitis C in children. Child Liver Study Group of Japan

Limited information is available regarding the histology of hepatitis C virus infection in children. The aim of this study was to determine the histological pattern of chronic hepatitis C (CHC) in children, and liver biopsy specimens from 109 pediatric patients with CHC were examined. Each biopsy specimen was evaluated based on a numerical scoring system for the stage of fibrosis (1-4), the grade of portal/periportal necroinflammation (0-4), the grade of lobular necroinflammation (0-4), and their sum (final grade). The histological lesions considered to be characteristic of chronic hepatitis were also evaluated. None of the children had liver cirrhosis, and 105 cases (97%) were stage 1 or 2. Only 4 children were stage 3. Two of these 4 cases showed hemosiderosis. A significant correlation was observed between the staging score and the final grade in the pediatric patients (r = .59; P < .0001). The histological characteristics of adult CHC, such as lymphoid aggregate, bile duct injury, and fatty changes, were also observed in the children. In conclusion, the majority of children with CHC presented with mild fibrosis, but a few showed CHC with lobular distortion and hemosiderosis. Frequent blood transfusion may aggravate hepatic lesions in pediatric CHC.

Effects of glycemic control on plasma 3-deoxyglucosone levels in NIDDM patients

OBJECTIVE

To clarify the effects of glycemic control on the level of 3-deoxyglucosone (3-DG), a reactive dicarbonyl compound, in plasma from diabetic patients.

RESEARCH DESIGN AND METHODS

Fasting plasma samples were collected from 15 healthy volunteers and 27 patients with NIDDM. Samples were collected from six poorly controlled patients before and after improved glycemic control for at least 2 months. Plasma 3-DG was determined by high-performance liquid chromatography (HPLC) as a 2,3-diaminonaphthalene derivative. We observed the relationship of 3-DG levels with plasma glucose or HbA1c levels and examined changes in 3-DG levels after glycemic control in the six patients.

RESULTS

Plasma 3-DG was significantly more increased in diabetic patients than in nondiabetic control subjects (31.8 +/- 11.3 vs. 12.8 +/- 5.2 ng/ml, means +/- SD, P < 0.001), but there was an approximately threefold difference in 3-DG levels among diabetic patients. 3-DG levels were well correlated with plasma glucose (r = 0.56, P < 0.005) and HbA1c levels (r = 0.74, P < 0.001) in diabetic patients. The improvement of hyperglycemia in six patients resulted in a significant decrease in 3-DG (35.2 +/- 13.2 vs. 21.3 +/- 3.4 ng/ml, P < 0.05).

CONCLUSIONS

The results indicate that the plasma glucose level is a predominant determinant of the plasma 3-DG level in diabetic patients and good glycemic control would be important to reduce this reactive metabolite.

Relationships between the hepatic intrinsic clearance or blood cell-plasma partition coefficient in the rabbit and the lipophilicity of basic drugs

The relationships between drug lipophilicity and hepatic intrinsic clearance (CLint,h) or red blood cell-plasma partition coefficients (D) have been elucidated for ten highly lipophilic basic drugs with apparent octanol-water partition coefficients at pH 7.4 (Papp,oct) or 150 or above. The true octanol-water partition coefficients of the non-ionized drugs (Poct) were used to determine CLint,h and D for the unbound drugs (CLint,h,f and Df, respectively), and CLint,h,f and Df for the non-ionized and unbound drugs (CLint,h fu and Dfu, respectively). The total clearance values were determined at steady state by infusion studies of individual drugs in rabbits. There was better correlation between log Poct and log CLint,h,fu (r = 0.974) than between log Poct and log CLint,h,f (r = 0.864). The D values were calculated from the blood-plasma concentration ratio. There was a better correlation between log Poct and log Dfu (r = 0.944) than between log Poct and log Df (r = 0.612). The regression equations obtained were CLint,h,fu = 0.0875 x Poct1.338 and Dfu = 0.0108 x Poct0.970, respectively. These results show that the CLint,h and D of highly lipophilic basic drugs can be predicted from Poct by taking fu into consideration. By applying these parameters to a physiologically based pharmacokinetic model it might be possible to predict the pharmacokinetics of unknown basic drugs.

Prediction of changes in the clinical pharmacokinetics of basic drugs on the basis of octanol-water partition coefficients

A physiologically based pharmacokinetic model for basic drugs has been established on the basis of octanol-water partition coefficients of the non-ionized, unbound drugs (Poct). The parameters for the physiological model in man were estimated from a regression equation obtained for the relationships between the Poct and the tissue-plasma partition coefficient, the hepatic intrinsic clearance (CLint,h) and the blood-to-plasma concentration ratio in rabbits. The plasma concentrations observed after intravenous administration of ten basic drugs (3.2 mg kg-1) to rabbits agreed with the levels predicted using the physiological model (r = 0.710-0.980). In man, the predicted plasma concentrations of basic drugs were in good agreement with reported values (r = 0.729-0.973), except for diazepam and pentazocine. Variations in plasma and brain-concentration profiles of clomipramine and nitrazepam in various disease states were simulated using the model. We assumed that the changes in unbound fraction of drug in serum (fp), CLint,h and the hepatic blood flow rate were from 0.25- to 4-fold that of the control and that fat volume changed by 0.2- to 5-fold. With regard to changes in fp, we predicted that the brain-plasma concentration ratio of clomipramine was 1.5- to 25-fold that of the control 24 h after intravenous administration, although the variations in the plasma concentration-time profiles were less marked. Plasma concentrations predicted for several basic drugs were in good agreement with reported values and this physiological model could be useful for predicting drug-disposition kinetics in man.

Hepatitis C virus RNA present in saliva but absent in breast-milk of the hepatitis C carrier mother

In order to examine whether saliva and breast-milk are mediators of the vertical transmission of hepatitis C virus (HCV) from an HCV carrier mother, serum, saliva, and breast-milk samples from 11 HCV carrier mothers were collected at the time of delivery, and at approximately 1- to 3-months intervals for as long as 30 months postpartum. Serum was also sampled from their children. All samples were analysed for the presence of HCV RNA, using the nested polymerase chain reaction method. No HCV RNA was detected in any breast-milk samples. In saliva, HCV RNA was detected in four of the 11 mothers (36%). These four mothers also had liver function abnormalities. Hepatitis C virus RNA was not detected in any serum samples of the children, and all children had normal liver function. The children were monitored for periods from 2 to 44 months. During this period, there was no evidence of virus transmission. Breast-milk is not likely to be a source of mother-to-child transmission of HCV. Maternal saliva may harbour HCV, but it may not result in infant infection.

Long-term evolution of fibrosis from chronic hepatitis to cirrhosis in patients with hepatitis C: morphometric analysis of repeated biopsies

To clarify the characteristics of fibrosis developed in the process from chronic hepatitis C to cirrhosis, a morphometric analysis of liver biopsy samples was conducted on 25 chronic hepatitis C patients and 20 chronic hepatitis B patients (controls). Hepatitis C patients were followed up for 3 to 23 years. The mean number of liver biopsies performed on these patients was 3.8. Each biopsy was evaluated for the degree of fibrosis by using two methods: a semiquantitative method with a staging scoring system, and morphometry using a computed image analysis system. A significant correlation was observed between the Stage and the area of fibrosis (AF = the ratio of the area of fibrosis to that of the entire tissue specimen). The AF in cirrhosis was significantly higher in hepatitis C patients than in hepatitis B patients. The ratio of AF in the last biopsy sample to AF in the initial biopsy sample was significantly higher in hepatitis C patients than in hepatitis B patients. Evolution from chronic hepatitis C to cirrhosis occurred more frequently in patients aged > or = 50 years, and this time period was 1.8 times shorter than that in patients aged < 50 years. AF in the initial biopsy related significantly to the period of evolution from chronic hepatitis C to cirrhosis. AF in the initial biopsy might be a predictive factor for prognosis.

Increased alanine uptake and lipid synthesis from alanine in isolated hepatocytes of Wistar-Kyoto fatty rats: an inhibitory effect of biguanides

To examine the pathophysiological characteristics of non-insulin-dependent diabetes mellitus, alanine metabolism in isolated hepatocytes of male Wistar-Kyoto (WKY) fatty rats (genetically obese and hyperglycemic) and their lean littermates was investigated. The effects of glucagon and the biguanides, metformin and buformin, on alanine metabolism were also studied by measuring alanine uptake and lipid synthesis from alanine. WKY fatty rats showed higher plasma insulin and lipid concentrations than lean rats at 5 as well as at 12 weeks of age. Alanine uptake into hepatocytes was increased in fatty rats only at 12 weeks of age compared with lean rats. Lipid synthesis from alanine in hepatocytes was increased in fatty rats at 5 and 12 weeks of age compared with lean rats. Glucagon increased alanine uptake into hepatocytes but did not affect lipid synthesis from alanine in both fatty and lean rats. Low concentrations (0.1 mM) of biguanides decreased lipid synthesis from alanine only in fatty rats without inhibiting alanine uptake into hepatocytes. These observations suggest that lipid synthesis from alanine in hepatocytes of WKY fatty rats is accelerated prior to the onset of diabetes mellitus, which might be associated with the development of diabetes, and that an inhibitory effect on increased lipid synthesis is one of the pharmacodynamic actions of biguanides.

Molecular cloning of a gene encoding a new type of metalloproteinase-disintegrin family protein with thrombospondin motifs as an inflammation associated gene

A cellular disintegrin and metalloproteinase (ADAM) is a new family of genes with structural homology to the snake venom metalloproteinases and disintegrins. We screened genes which were selectively expressed in the cachexigenic colon 26 adenocarcinoma subline in vivo. It was found that one novel cDNA clone, identified as a cachexigenic tumor selective gene, encodes a cysteine-rich protein which shows a sequence similarity to that of both the snake venom metalloproteinases and thrombospondins. We named this cDNA clone A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS-1). ADAMTS1 consists of six domains, 1) a pro- and 2) a metalloproteinase, 3) a disintegrin-like, 4) a thrombospondin (TSP) homologous domain containing TSP type I motif, 5) a spacer region, and 6) COOH-terminal TSP submotifs. Unlike other ADAMs, ADAMTS-1 does not possess a transmembrane domain and is a putative secretory protein. Therefore, ADAMTS-1 is a new type of ADAM family protein with TSP type I motifs. We demonstrated that the TSP homologous domain containing the TSP type I motif of ADAMTS-1 is functional for binding to heparin. ADAMTS-1 mRNA could be induced by stimulating colon 26 cells with an inflammatory cytokine, interleukin-1, in vitro. Moreover, intravenous administration of lipopolysaccharide in mice selectively induced ADAMTS-1 mRNA in kidney and heart. These data suggest that ADAM-TS-1 may be a gene whose expression is associated with various inflammatory processes as well as development of cancer cachexia.