Immortalization of human urothelial cells by human papillomavirus type 16 E6 and E7 genes in a defined serum-free system.

UNLABELLED: Normal human epithelial cell cultures exhibit a limited (although different between tissues) lifespan in vitro. In previous studies, urothelial cell cultures were immortalized using retroviral transformation with human papillomavirus type 16 E6 and E7 genes, in undefined culture systems containing serum or bovine pituitary extract. OBJECTIVE: Due to the variability of results in such systems, we instead developed a procedure for the immortalization of urothelial cells using a defined, serum-free culture system. METHOD AND RESULTS: Immortalization through retroviral transformation with human papillomavirus type 16 E6 and E7 was successful, and transformation of urothelial cells conferred an extended over normal lifespan and restored telomerase activity. Transformed cells retained typical morphology and exhibited a similar growth rate, cytokeratin immunoreactivity pattern, and response to growth factors as observed in untransformed cells. Karyotype analysis revealed a gradual accumulation of genetic mutations that are consistent with previously reported mutations in epithelial cells transformed with human papillomavirus type 16 E6 and E7. CONCLUSION: The ability to extend the in vitro lifespan of cells holds the potential to reduce the continuous need for tissue samples and to enable complete investigations with one cell line.

Pharmacokinetics of oral zidovudine (azidothymidine) in patients with AIDS when administered with and without a high-fat meal.

Zidovudine is the only drug currently approved for the treatment of HIV infection. The present recommended doses found to be efficacious in patients with AIDS (200 mg every 4 h) achieve serum zidovudine concentrations greater than 0.267 micrograms/ml (1 mumol/l). Since patients often take zidovudine with food, we have investigated the effect of a liquid high-fat meal on the rate of absorption of zidovudine and on the peak serum concentration achieved. Eight patients received their usual dose of zidovudine (100 mg or 250 mg), with and without a liquid high-fat meal, on two separate study days, in a randomized crossover fashion. Blood and urine samples were collected over a 4-h period. In the absence of food, zidovudine is rapidly absorbed; the time to reach maximal serum concentration (Tmax) was 0.68 (+/- 0.25) h and the mean peak serum concentration (Cmax) achieved was 0.49 (+/- 0.3) micrograms/ml (dose normalized to 100 mg dose). In the presence of a high-fat meal, Tmax was significantly prolonged [1.95 (+/- 0.69) h; P less than 0.05] and the Cmax reduced [0.245 (+/- 0.12) micrograms/ml; P less than 0.05]. This demonstrates that to achieve maximal zidovudine serum concentrations, patients should take this medication on an empty stomach.

Verapamil inhibits ethanol elimination and prolongs the perception of intoxication.

Ten young healthy men received verapamil (80 mg every 8 hours for 6 days) or placebo in a blinded, randomized, crossover design. On the sixth day, ethanol was administered as a single oral dose (0.8 gm/kg), and blood samples were collected over the following 12 hours for determination of verapamil, norverapamil, and ethanol concentrations. Compared with placebo, verapamil increased the peak blood ethanol concentration (106.45 +/- 21.40 to 124.24 +/- 24.74 mg/dl, p less than 0.05) and area under the ethanol concentration versus time curve (365.67 +/- 93.52 to 475.07 +/- 97.24 mg.hr/dl, p less than 0.005). Verapamil areas under the concentration versus time curves (AUC) were positively correlated (r = 0.71, p less than 0.05) to increased ethanol blood AUC values. Each subject's perception of ethanol intoxication was measured by use of a simple visual analog scale. Compared with placebo, verapamil significantly increased area under the effect versus time curve (10.19 +/- 7.6 to 13.83 +/- 7.81 cm.hr, p less than 0.002) but did not change the peak effect or time to peak effect. Ethanol effect versus concentration plots were not significantly different between verapamil and placebo treatment phases when increased ethanol concentrations during verapamil therapy were taken into account. The findings of our study suggest that verapamil significantly inhibits ethanol elimination, resulting in elevated blood ethanol concentrations that prolong the intoxicating effects of alcohol.

Theophylline metabolism: variation and genetics.

Variation of theophylline metabolism in 54 healthy, nonmedicated adults (13 monozygotic [MZ] twin pairs, 11 dizygotic [DZ] twin pairs, and 6 single individuals) was assessed by kinetic study. Elimination rate constant, clearance (Cl), t1/2, and apparent volume of distribution, as well as urine excretion of unchanged theophylline and of the three major metabolites (1-methyluric acid, 3-methyl-xanthine, and 1,3-dimethyluric acid) were studied. Smokers and men had increased theophylline elimination rates compared to nonsmokers and women. Identical (MZ) twins resembled each other more closely than nonidentical (DZ) twins in the various kinetic parameters, but mean intrapair differences between MZ and DZ twins for all but one of the serum and urinary parameters examined (including t1/2) were not statistically significant. Correspondingly, estimates of heritability and of intrapair correlation coefficients showed a smaller contribution of genetic factors to variation in theophylline metabolism than had been reported for other drugs investigated by twin studies. Nevertheless, in the family of the individual with the longest theophylline t1/2, the operation of a rare major gene retarding theophylline metabolism could not be excluded. A father and two out of four children had very slow Cls. This finding would be consistent with, but does not prove, monogenic inheritance.

Changes in antipyrine and indocyanine green kinetics during nifedipine, verapamil, and diltiazem therapy.

Ten healthy subjects received oral antipyrine and intravenous indocyanine green (ICG) alone and after 5 days of oral nifedipine, diltiazem, and verapamil. Antipyrine clearance decreased during verapamil (range 4% to 26%) and diltiazem (6% to 24%) therapy (P less than 0.001) but did not change during nifedipine treatment. Antipyrine t1/2 also increased during verapamil and diltiazem treatment (P less than 0.001). ICG clearance did not change during diltiazem therapy but increased during dosing with nifedipine and verapamil (P less than 0.05). Estimated liver blood flow (derived from ICG clearance and hematocrit) also increased during verapamil (mean 33%) and nifedipine (mean 27%) treatment (P less than 0.05). Drug interactions with other liver-metabolized drugs may occur during therapy with these calcium antagonists. Nifedipine appears to increase liver blood flow whereas diltiazem inhibits oxidative drug metabolism. Drug interactions with verapamil could involve both mechanisms.

Single and multiple doses of oral cimetidine do not change liver blood flow in humans.

Liver blood flow was measured in 10 healthy men for 6 hours after single (300 mg) and multiple (300 mg every 6 hours for 5 days) oral doses of cimetidine. Blood flow measurements were determined in the superior mesenteric and hepatic arteries and in the intrahepatic branches of the portal and hepatic veins by use of a duplex Doppler ultrasound technique. Compared with baseline measurements obtained before drug administration, cimetidine treatment did not change blood flow in any of the four blood vessels. Cimetidine serum concentrations and pharmacokinetic parameters were similar to those reported in other studies conducted in healthy adults. The findings of this study indicate that single and multiple 300 mg doses of oral cimetidine do not change liver blood flow.

Acquired immunodeficiency syndrome. Cerebrospinal fluid findings in patients before and during long-term oral zidovudine therapy.

Fifty-two patients with acquired immunodeficiency syndrome were enrolled in this study to evaluate the relationship between cerebrospinal fluid (CSF) zidovudine concentrations and neurologic and human immunodeficiency virus (HIV) culture findings. Paired HIV-CSF culture and neurologic measurements were available in 30 and 45 patients, respectively. Twenty-nine patients were assessable for zidovudine CSF concentrations. Patients underwent lumbar puncture and neurologic testing before and after 8 weeks or more of oral zidovudine therapy (600 to 1500 mg/d). After 8 weeks of therapy, the frequency of HIV isolation from CSF cultures was unchanged. Significant neurologic improvement by examination was noted in 61.5% (32/52) of the patients. The median CSF zidovudine concentration among 29 patients was 0.047 mg/L (range, 0.015 to 0.198 mg/L). No correlation between CSF zidovudine concentration, cumulative dose, or HIV isolation from CSF and persistence or resolution of neurologic symptoms or signs was observed. The mechanisms by which zidovudine improves neurologic function are unclear and appear unrelated to direct clearance of virus from CSF.

Zidovudine disposition during hemodialysis in a patient with acquired immunodeficiency syndrome.

Zidovudine (azidothymidine, AZT) disposition was examined during a hemodialysis session in an HIV-infected male with mesangial proliferative glomerulonephritis. Serum concentrations of zidovudine and its glucuronidated inactive metabolite (G-ZDV) were measured by HPLC. Zidovudine pharmacokinetics were similar to previous reports in patients with normal renal function, however, G-ZDV concentrations were significantly elevated (23-440 times zidovudine concentration). Hemodialysis did not appreciably reduce zidovudine or G-ZDV levels. Significance of chronically elevated G-ZDV levels is unknown.

Balanced reciprocal translocation mosaicism: how frequent?

We describe 2 cases of balanced reciprocal translocation (BRT) mosaicism. The frequency of this aberration in the population referred to our laboratory was determined and compared to those frequencies reported in the literature by other clinical cytogenetics laboratories. The extent of BRT mosaicism was also examined in surveys of parental populations, which are less likely to have a bias due to ascertainment on the basis of abnormal phenotype. the frequencies in the postnatal and prenatal populations examined in this study were calculated to be 5.7 x 10(-5) (95% confidence interval is 3.2-8.2 x 10(-5)) and 4.1 x 10(-5) (95% confidence interval is 2.0-6.2 x 10(-5)). However, in view of the extent of variation reported in the various studies, these estimates should be considered first approximations of the true frequency.

Familial cryptic (20;21) translocation identified by in situ hybridization technologies.

We report on a familial cryptic (20;21) translocation [(t20;21)] that was initially suspected with the observation of a single chromosome 21 specific signal in an interphase nuclei by in situ hybridization (FISH) study performed on a 34-week gestation amniotic fluid specimen. The genetic amniocentesis was prompted by the presence of fetal anomalies detected by ultrasound. In addition, there was a family history of a maternal uncle with mental retardation and multiple malformations and an apparently normal karyotype. No obvious aberration could be detected in the G-banded karyotype prepared from the amniotic fluid specimen. A FISH study using a chromosome 21 specific long arm probe and chromosome 20 whole chromosome paint, however, showed an unbalanced rearrangement in the fetus [46,XY, der(21)t(20;21)(q13.2;q22.13 or 22.2) mat]. The mother and maternal grandmother were demonstrated to be balanced translocation carriers. These results were confirmed by multicolor karyotyping. This familial aberration was discovered by chance in the interphase FISH analysis. Our experience with this case, however, serves to emphasize the importance of the reevaluation of patients with mental retardation and congenital malformations of unknown cause and prudent use of multicolor karyotyping in the detection of cryptic cytogenetic rearrangements.

Is C-reactive protein useful in the management of children with suspected bacterial meningitis?

C-reactive protein (CRP) was evaluated in both serum and cerebrospinal fluid in 119 patients to determine if either or both measurements were of clinical value in the diagnosis of bacterial meningitis. CSF C-reactive protein is too insensitive (sensitivity = 66%) to be useful, while serum CRP is too nonspecific for routine application. Serum CRP may have a role if used selectively in those patients with a low-grade CSF pleocytosis and a negative Gram's stain.

Lack of interaction between glipizide and co-trimoxazole.

To identify the effects of co-trimoxazole on the elimination and disposition kinetics of glipizide, eight healthy male volunteers were studied in an unblinded, randomized, cross-over trial with two phases (no treatment or co-trimoxazole 160/800 mg twice a day). During each phase, subjects were treated at home for 7 days with one of the treatment regimens, followed by a 24-hour hospitalization for a single-dose challenge with 10-mg oral glipizide and detailed blood studies. A 7-day washout period was interspersed between the phases. Pharmacokinetic and pharmacodynamic parameters were determined and compared using the Student's t-test for paired observations. Glipizide area under the curve (AUC), clearance, and half life for treatment and control phases were 5758 +/- 1874 versus 5176 +/- 1505 micrograms/L/hour (P = .21), 0.41 +/- 0.15 versus 0.45 +/- 0.14 mL/min/kg (P = .27), and 5.13 +/- 2.10 versus 3.95 +/- 1.37 hours (P = .04), respectively. Twenty-four-hour glucose AUCs for treatment and control phases were 112.24 +/- 8.76 versus 114.86 +/- 11.98 mmol/L/hour (P = .55), respectively. The only parameter reaching statistical significance was glipizide half life, but the difference is of doubtful clinical significance because of difficulty in identifying a clear elimination phase in several subjects. It is concluded that co-trimoxazole administration did not significantly alter glipizide disposition and elimination kinetics in this study population.

Glipizide pharmacokinetics: effects of age, diabetes, and multiple dosing.

Aging and disease may contribute to alterations in drug pharmacokinetics. The purpose of this study was to determine the effects of aging, the presence of NIDDM, and multiple dosing on the pharmacokinetics of glipizide, an oral hypoglycemic drug. Ten healthy young men (under age 25), ten healthy older men (over age 65) and 15 older diabetic men ingested a single 5 mg tablet of glipizide after an overnight fast. Blood samples for measurement of serum glipizide were obtained over the next 24 hours. The study was repeated in the diabetics after 2 weeks of daily therapy. The mean values for Tmax (range 2.0-2.5 hours), Cmax (385-465 micrograms/l), and t1/2 (4.0-4.2 hours) were not significantly different in the three populations after single doses of glipizide. Several subjects in each population had slow absorption, with peak concentrations delayed for up to 12 hours. Only one elderly diabetic subject had evidence of drug accumulation at steady state. AUC, Cl, Vss and V area were not significantly different in the three populations or at steady state, but there was a trend for AUC to be smaller and each of the other parameters to be increased in the older diabetics. The young subjects had a significantly higher fp (0.83%) than either of the two elderly groups (0.55-0.64%), but Cl int did not differ between groups. Age, diabetes, and multiple dosing appear to have little effect on the pharmacokinetics of glipizide and should have little influence on the clinical response to this drug.

Chromosomal changes in a dedifferentiated chondrosarcoma: a case report and review of the literature.

The chromosome abnormalities observed in a dedifferentiated chondrosarcoma are reported. A new molecular cytogenetic technique, spectral karyotyping, was used to identify and confirm structural rearrangements in this case. A review of the literature revealed that nine cases have been reported, in eight of which a complete description of the cytogenetic abnormalities was described. Structural aberrations were most frequently reported in chromosomes 1 and 9, and chromosomes 7 and 19 were most frequently observed to be involved in numerical aberrations (trisomy and tetrasomy). In chondrosarcomas, structural aberrations in chromosomes 1 and 9 and trisomy or tetrasomy of chromosome 7 are among the more frequently observed aberrations.

Pharmacokinetics and pharmacodynamics of glipizide after once-daily and divided doses.

STUDY OBJECTIVE: To determine the pharmacokinetics and pharmacodynamics of glipizide given as a single, oral, 20-mg dose, versus three different divided-dose regimens totaling 20 mg each. DESIGN: Randomized (in order of dosing regimens), open-label, crossover study. SETTING: University medical center clinical research center. PATIENTS: Six subjects with noninsulin-dependent diabetes mellitus. INTERVENTIONS: Patients were studied on four separate occasions separated by at least 3 days. The divided-dose regimens were designed to simulate delayed absorption of the drug over 2, 4, and 8 hours. Blood samples for measuring glipizide, glucose, and C-peptide were obtained over 24 hours. MEASUREMENTS AND MAIN RESULTS: Glipizide peak concentrations and time to peak differed significantly with the dosage schedule; when smaller doses were administered more often, peak concentrations were lower and more delayed. The mean values for area under the curve from time zero to infinity (range 7240.7-10,001.8 micrograms.L-1.hr-1; 16,226-22,414 nmol.L-1.hr-1), clearance (0.44-0.64 ml.min-1.kg-1; 0.07-0.11 ml.sec-1.kg-1), post-distribution phase volume (0.17-0.25 L.kg-1), and half-life (4.2-5.4 hrs) were not significantly different among regimens. Neither morning fasting glucose nor maximum and minimum times and concentrations of glucose and C-peptide over 24 hours were statistically different among regimens. Similarly, no significant differences were found in area under the concentration-time curve for glucose and C-peptide measured over 2.5 hours after each meal and from time zero to 24 hours. CONCLUSIONS: The timing of a glipizide dose in relation to a meal and simulated delayed or prolonged absorption appear to have little influence on the drug's pharmacodynamic effects.

Drug-specific Fab therapy in drug overdose.

The use of digoxin-specific fragments, antigen-binding (Fab) for antidotal therapy of severe digitalis intoxication is rapidly becoming a treatment of choice. Furthermore, studies with this mode of drug-specific therapy using Fab specific for desipramine and for phencyclidine suggest that this treatment may be applicable to a variety of other drugs or drug classes. As Fab technology has advanced, so have laboratory methods for monitoring the efficacy of treatment.

Caffeine and its dimethylxanthine metabolites in two cases of caffeine overdose: a cause of falsely elevated theophylline concentrations in serum.

Two children ingested over-the-counter medications containing caffeine, resulting in significant caffeine overdose. Measured concentrations of caffeine were as high as 176 and 128 mg/L. We have described the elimination of caffeine and its dimethylxanthine metabolites, paraxanthine, theophylline, and theobromine in these cases. The apparent theophylline concentrations determined after caffeine ingestion were dependent upon the method of measurement. Use of one published reversed-phase HPLC method, which does not separate theophylline from paraxanthine, resulted in overestimation of theophylline by 225 to 513%. Use of an enzyme immunoassay procedure resulted in a lesser degree of overestimation (142-383%), which was due, in part, to cross-reactivity with extremely high concentrations of caffeine and paraxanthine. The measurement of caffeine concentrations in the management of caffeine overdose is of limited clinical usefulness; likewise, measurement of theophylline concentrations is generally not indicated, and may be misleading unless a highly specific assay is used.

Analysis of digoxin concentrations in serum by fluorescence polarization immunoassay: an evaluation.

The Abbott TDx fluorescence polarization immunoassay was evaluated for the determination of serum digoxin concentrations. Within-assay precision was less than 4% coefficient of variation (CV) for concentrations ranging from 0.64 to 3.75 ng/mL. Between-assay precision was 14.5% CV at 0.75 ng/mL, 5.7% CV at 1.50 ng/mL, and 4.9% CV at 3.48 ng/mL. Sensitivity to 0.2 ng/mL digoxin was confirmed. Correlation of 86 patient specimens assayed by radioimmunoassay (RIA) with the TDx showed the following: correlation coefficient r = 0.94, slope = 0.93, intercept = 0.11, and Sy/x = 0.19. Recovery from serum at concentrations of 0.97 ng/mL and 4.50 ng/mL averaged 98%. No significant interference from lipemia, icteria, or hemolysis was observed. Spironolactone showed no cross-reactivity with the antibody, while digitoxin exhibited significant cross-reactivity. Compared to the RIA procedure, the TDx assay was more rapid, reliable and, in this clinical situation, more cost effective.

Simplified high performance liquid chromatographic quantitation of antipyrine.

Antipyrine is used as an index of hepatic drug metabolism. The authors devise a simple and rapid high performance liquid chromatography method to quantitate antipyrine in serum with small volume (50 microliters). Minimal sample preparation is needed and the assay is sensitive to concentrations of 0.2 micrograms/ml. Mobile phase consists of 35% methanol in 67 mM phosphate buffer pH 3.5 with antipyrine detected by monitoring the eluate at 225 and 254 nm. Within-run and run-to-run coefficients of variation are less than or equal to 2.8 and 4.6%, respectively. Recoveries from serum average 100.8%. It is concluded that this technique for antipyrine is simple, rapid, and well characterized.