Antigenic similarity between cells transformed by ultraviolet radiation in vitro and in vivo.

Cells of the 10T 1/2 mouse fibroblast line transformed in vitro by ultraviolet radiation are antigenically similar to those from skin cancers produced in mice by repeated exposure to ultraviolet radiation. Both types of tumor cells grew preferentially in ultraviolet-irradiated syngeneic mice relative to untreated animals, and both were recognized by ultraviolet radiation-induced tumor-specific suppressor lymphocytes. These properties were not shared by 10T 1/2 cells transformed in vitro by x-rays or 3-methylcholanthrene.

[Impact of maternal risky behaviors on the behaviors of children born to adolescent and young mothers].

Objective: To examine the impact of maternal risky behaviors on the behaviors of children born to adolescent and young mothers. Methods: Adolescents and young Chinese mothers were recruited from an integrated young mother supportive program in Hong Kong between January and June 2015. Eligible mothers were asked to complete a questionnaire on their sociodemographic characteristics and history of risky behavior as well as their children's behaviors. Multiple regression analyses were conducted to explore the association between maternal risky behaviors and their children's behaviors. Results: Among 201 respondents, there were 187 (93.0%) ex-drinkers, 136 (67.7%) ex-smokers, and 83 (41.3%) ex-addicts. Compared to the reference group, children of mothers with drug use behaviors were more likely to have abnormal SDQ total difficulties scores (odds ratio 2.60, P=0.01), those of ex-drinking mothers had more behavioral difficulties and more conduct problems (B=3.82 and 1.37, P both=0.01) and those of ex-smoking mothers had more conduct problems (B=0.74, P=0.01) after adjustment for confounders. Children of active drug-taking mothers also had more emotional symptoms (B=1.77, P=0.04) and hyperactivity/inattention problems (B=2.14, P=0.03). Conclusion: The history of mother's risky behavior was significantly associated with the behavioral problems of the children.

Plasma L-[18F]6-fluorodopa input function: a simplified method.

This article describes a simplified method for the determination of the L-[18F]6-fluorodopa (FDOPA) fraction time course that takes advantage of the strong correlation between the radioactivity ratio (metabolites/FDOPA) and time. Serial arterial blood samples are collected for assay of plasma total radioactivities following an intravenous injection of FDOPA into carbidopapretreated subjects. In addition, a single plasma sample, collected late in the study and analyzed for FDOPA fraction, is sufficient to determine accurately the time course of the FDOPA concentration in plasma. The validated straight-line method greatly simplifies blood analysis for routine positron emission tomography FDOPA studies.

Evaluation of dopaminergic presynaptic integrity: 6-[18F]fluoro-L-dopa versus 6-[18F]fluoro-L-m-tyrosine.

The effectiveness of 6-[18F]fluoro-L-m-tyrosine (6FMT) to evaluate dopamine presynaptic integrity was compared to that of 6-[18F]fluoro-L-dopa (6FDOPA) in vivo by positron emission tomography (PET). Six normal and six 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned monkeys received 6FDOPA and 6FMT PET scans on separate occasions with identical scanning protocols. Four measures, the rate of uptake of tracer into striatum using either the arterial input function (Ki) or the activity in the occipital cortex as the input function (Kc), the rate of loss of striatal radioactivity (k(loss)), and an index of "effective turnover" of dopamine (k(loss)/Ki), were obtained for both tracers during extended PET studies. 6-[18F]Fluoro-L-m-tyrosine was as effective as 6FDOPA in separating normals from MPTP-lesioned subjects on the basis of the uptake rate constants Ki and Kc. However, in contrast to 6FDOPA, it was not possible to differentiate the normal from the lesioned animal using k(loss) or k(loss)/Ki for 6FMT. Thus, FMT appears to be a reasonable, highly specific tracer for studying the activity of aromatic dopa decarboxylase enzyme as an index of presynaptic integrity. However, if one is interested in investigating further the metabolic pathway and obtaining an in vivo estimate of the effective turnover of dopamine (after pharmacologic manipulation, for example), 6FDOPA remains the tracer of choice.

Effects of catechol-O-methyltransferase inhibition on the rates of uptake and reversibility of 6-fluoro-L-Dopa trapping in MPTP-induced parkinsonism in monkeys.

The uptake rate constant and the loss rate constant that expresses the reversibility of the uptake process of 6-[18F]fluoro-L-Dopa (FDOPA) were measured by positron emission tomography in the striatum of normal rhesus monkeys and in monkeys with unilateral lesions of the dopaminergic nigro-striatal pathway, induced by intracarotid injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Each animal was studied twice: with and without pretreatment of the catechol-O-methyltransferase (COMT) inhibitor Ro 40-7592, tolcapone. After pretreatment with tolcapone, there was a very significant increase in plasma FDOPA throughout the course of the study, accompanied by a significant decrease in its main metabolite, 3-O-methylfluorodopa. Tolcapone did not induce a significant change in the uptake rate constant in either the normal or the MPTP-treated striatum. However, after tolcapone pretreatment, there was a significant decrease in the loss rate constant in the MPTP-treated striatum (25%) and a smaller, non-significant decrease in the normal striatum (13%). It is concluded that the COMT inhibitor tolcapone exhibits clear peripheral and central activity. As compared to peripheral COMT inhibitors, this central effect may help preserve and stabilize the synaptic levels of DA and, thus, further improve the effects of L-DOPA therapy in parkinsonian patients.

Quantitative comparison of three- and two-dimensional PET with human brain studies.

UNLABELLED: The aim of this study was to test the quantitation accuracy of three-dimensional PET in brain scanning. METHODS: Three-dimensional data from 11 human subjects were tested using 11C-dihydrotetrabenazine, 11C-Schering 23390 and 18F-FDG as tracers. Two-dimensional scans were performed on the same subjects and the distribution volume, distribution volume ratio and local metabolic rate of glucose (LMRGlu) values obtained from these were used as reference. Three-dimensional data were processed as follows: iterative convolution subtraction scatter correction, detector normalization including radial and axial geometric factors, attenuation correction extracted from a two-dimensional transmission scan, Kinahan-Rogers reconstruction and region-of-interest-based sensitivity calibration. RESULTS: No major systematic differences between the two methods were found. The agreement between the two-dimensional and three-dimensional data was within 5%. Although statistical analysis generally did not show this difference to be significant, reliability analysis indicated that comparing two-dimensional and three-dimensional data might introduce some inaccuracies. CONCLUSION: Three-dimensional PET yields quantitatively valid results for brain scanning.

Graphical analysis of 6-fluoro-L-dopa trapping: effect of inhibition of catechol-O-methyltransferase.

UNLABELLED: Graphical methods to analyze tracer time-course data allow reliable quantitation of the rate of incorporation of tracer from plasma into a "trapped" kinetic component, even when the details of the kinetic model are unknown. Applications of the method over long time periods often expose the slow reversibility of the trapping process. In the extended graphical method, both trapping rate and a presumed first-order loss rate constant are estimated simultaneously from the time-course data. METHODS: We applied the extended graphical method to 6-fluoro-L-dopa (6-FD), simultaneously estimating the rate of uptake (Ki) and the rate constant for loss from the trapped component (K(loss)) in a single fitting procedure. We applied this approach to study the effects of two catechol-O-methyl-transferase inhibitors on the kinetics of 6-FD in cynomolgus monkeys. RESULTS: Inhibition of peripheral O-methylation with either inhibitor, confirmed by high-performance liquid chromatography analysis of labeled compounds in arterial plasma, had no significant effect on Ki, in agreement with previously reported studies. In contrast, tolcapone, a catechol-O-methyl-transferase inhibitor, having central effects in addition to peripheral effects at the dosage used, decreased K(loss) by 40% from control values (p < 0.002), whereas nitecapone, which has no known central activity, had no significant effect. CONCLUSION: This method provides insight into the neurochemical basis for the kinetic behavior of 6-FD in both health and disease and may be used to define the action of centrally active drugs that influence the metabolism of dopamine.

Reproducibility studies with 11C-DTBZ, a monoamine vesicular transporter inhibitor in healthy human subjects.

UNLABELLED: The reproducibility of (+/-)-alpha-[11C] dihydrotetrabenazine (DTBZ) measures in PET was studied in 10 healthy human subjects, aged 22-76 y. METHODS: The scan-to-scan variation of several measures used in PET data analysis was determined, including the radioactivity ratio (target-to-reference), plasma-input Logan total distribution volume (DV), plasma-input Logan Bmax/Kd and tissue-input Logan Bmax/Kd values. RESULTS: The radioactivity ratios, plasma-input Bmax/Kd and tissue-input Bmax/Kd all have higher reliability than plasma-input total DV values. In addition, measures using the occipital cortex as the reference region have higher reliability than the same measures using the cerebellum as the reference region. CONCLUSION: Our results show that DTBZ is a reliable PET tracer that provides reproducible in vivo measurement of striatal vesicular monoamine transporter density. In the selection of reference regions for DTBZ PET data analysis, caution must be exercised in circumstances when DTBZ binding in the occipital cortex or the cerebellum may be altered.

Reproducibility of the distribution of carbon-11-SCH 23390, a dopamine D1 receptor tracer, in normal subjects.

UNLABELLED: The reproducibility of [11C]SCH 23390 in PET was studied in 10 normal human subjects. METHODS: The scan-to-scan variation of several measures used in PET data analysis, including the radioactivity ratio, plasma-input Logan total distribution volume (DV), plasma-input Logan DV ratio (DVR) and tissue-input Logan Bmax/Kd values, was determined. RESULTS: There were significant correlations among the radioactivity ratio, plasma-input DVR and tissue-input Bmax/Kd. With the cerebellum as the reference region, these three measures also had high reliability (86%-95%), high between-subject s.d. (7.7%-11.3%) and small within-subject s.d. (2.3%-3.6%), indicating that they are comparable and useful measures for the assessment of dopamine D1 receptor binding. CONCLUSION: The radioactivity ratio and the tissue-input Bmax/Kd may be preferred methods for the evaluation of dopamine D1 receptor binding because these two methods do not require arterial blood sampling and metabolite analysis. Our results show that cerebellum is a reliable reference region for SCH 23390. When the Logan plasma-input function method is used in data analysis for SCH 23390, DVRs rather than total DV values should be used because of the poor reliability of the DV values and their lack of correlation with other measures. Carbon-11-SCH 23390 is thus a reliable and reproducible ligand for the study of dopamine D1 receptor binding by PET.

Azathioprine metabolism: pharmacokinetics of 6-mercaptopurine, 6-thiouric acid and 6-thioguanine nucleotides in renal transplant patients.

Despite extensive clinical experience with azathioprine (AZA), the disposition of various AZA metabolites remains obscure. We therefore evaluated the pharmacokinetics of three AZA metabolites: 6-mercaptopurine (6-MP), the immediate metabolite; 6-thiouric acid (6-TU), the final end product; and 6-thioguanine nucleotides (TGN), the active moiety; in eight renal transplant patients after oral administration of AZA. The low peak plasma 6-MP level of 73.7 +/- 23.7 ng/mL (mean +/- SD) and the short half-life (t1/2) of 1.9 +/- 0.6 hours suggest rapid conversion of 6-MP to other metabolites. A peak plasma 6-TU concentration of 1210 +/- 785 ng/mL was observed at 3.5 +/- 0.6 hours after the AZA dose. The strong correlation between 6-TU t1/2 and serum creatinine (r = 0.98, P = .0008) supported our previous work showing that 6-TU is primarily excreted by the kidneys. The total TGN levels in red blood cells (RBCs) in each patient remained largely unchanged over 24 hours with the intraindividual coefficient of variation ranging from 4.4% to 29.8%. In comparison, the mean TGN level varied considerably between patients, and ranged from undetectable to 413 pmol per 8 X 10(8) RBCs. However, there was no apparent correlation between white cell counts on day 0 (P greater than .5), day 7 (P greater than .5), or day 14 (P greater than .5) and RBC TGN level. The persistence of TGN in body tissues thus provides a pharmacokinetic rationale for the conventional once or twice daily AZA regimen.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of monoamine oxidase and catechol-O-methyltransferase inhibition on dopamine turnover: a PET study with 6-[18F]L-DOPA.

The consequences of monoamine oxidase and catechol-O-methyltransferase inhibition on the effective turnover of dopamine were investigated using 6-[18F]L-3-4-dihydroxyphenylalanine (6-[18F]L-DOPA) and positron emission tomography. The effective dopamine turnover was expressed as the ratio between the rate of reversibility of 6-[18F]L-DOPA trapping (k[loss]) and the rate of uptake of 6-[81F]L-DOPA (Ki) in the striatum of normal cynomolgus monkeys. The monkeys received 6-[18F]L-DOPA scans, untreated or after pretreatment with either the peripheral catechol-O-methyltransferase inhibitor nitecapone; the peripheral and central catechol-O-methyltransferase inhibitor tolcapone; the monoamine oxidase inhibitors deprenyl or pargyline; a combination of tolcapone and the monoamine oxidase inhibitors. Tolcapone alone or combined with the monoamine oxidase inhibitors produced a significant decrease in the dopamine turnover (55 to 65%). Neither nitecapone nor monoamine oxidase inhibition alone produced significant changes. These results may have implications for the use of central catechol-O-methyltransferase inhibitors added to routine levodopa therapy in parkinsonian patients.

The therapeutic use of azathioprine in renal transplantation.

This review discusses the pharmacokinetics, mechanism of action, clinical use, toxicities, drug interactions, and possible approaches for therapeutic monitoring of azathioprine (AZA). The drug has been used extensively in posttransplant immunosuppressive protocols. Its therapeutic use is hampered by the development of toxicities, however, especially leukopenia, which is a common criterion for dosage adjustment. Azathioprine is rapidly converted in the liver and erythrocytes to 6-mercaptopurine (6MP), which is eventually metabolized to inactive 6-thiouric acid (6TU). The terminal half-lives of AZA and 6MP are 50 and 74 minutes, respectively. While renal dysfunction does not alter the disposition of AZA, hepatic insufficiency attenuates the pharmacologic activity. Immunosuppression depends on the formation of active intracellular thiopurine ribonucleotides, although AZA itself may block antigen recognition. Individualization of AZA regimens by determining tissue concentrations of thioguanine nucleotides, and plasma concentrations of AZA, 6MP, or 6TU may improve the risk:benefit ratio.

The pharmacoeconomics of renal transplantation: increased drug costs with decreased hospitalization costs.

We evaluated the economic and clinical effects of two immunosuppressive drug regimens used to treat recipients of human leukocyte antigen (HLA)-identical sibling donor renal transplants during the first posttransplant year. We compared consecutive patients in two groups of 30 who were given either antilymphoblast globulin (ALG), azathioprine, plus prednisone or cyclosporine, azathioprine, and prednisone for immunosuppression. We standardized all dollar values, costs and charges, to the 1986 level using our hospital's health care charge inflation rate. There were no significant differences between the two treatment groups for actual patient (100% vs 93%; p = 0.51) and graft survival rates (100% vs 93%; p = 0.51), average serum creatinine level (1.0 +/- 0.3 vs 1.0 +/- 0.2 mg%; p = 0.46), and most recent creatinine level (1.4 +/- 0.3 vs 1.4 +/- 0.7 mg%; p = 0.45). The average cyclosporine-azathioprine-prednisone costs were $3987/patient more for the first year of therapy than for ALG-azathioprine-prednisone. However, the former regimen produced an average of $9543/patient less in total hospitalization charges. This was due to both a shorter initial hospital stay and a decreased rate of rehospitalization, with a lower frequency of acute rejection episodes (p = 0.001) and infectious complications (p = 0.05). We conclude that, although this cyclosporine-containing protocol was associated with increased drug costs, it is justified by decreased hospitalization charges that resulted from improved efficacy and safety.

Routes of administration and effect of carbidopa pretreatment on 6-[18F]fluoro-L-dopa/PET scans in non-human primates.

In 6-[18F]fluoro-L-dopa (Fdopa)/positron emission tomography (PET) studies, carbidopa pretreatment increases the Fdopa bioavailability to the brain and enhances the intensity of striatal PET images. Different PET research teams have used various carbidopa doses and routes of administration in non-human primate studies. The purpose of this study was to examine the plasma profiles of carbidopa and the effect of the route of administration of carbidopa on a Fdopa/PET scan. Cynomolgus monkeys were given carbidopa either orally (5 mg/kg), intraperitoneally (2.5 and 5 mg/kg) or intravenously (5 mg/kg) 60-90 min prior to the Fdopa injection. Carbidopa-treated monkeys were compared to monkeys without carbidopa treatment. No carbidopa was detected in the plasma samples when it was given orally, possibly due to poor absorption in the gastrointestinal tract. In addition, the striatal and cortical activities were not statistically different from those of the untreated monkeys, indicating that little or no inhibition of the peripheral decarboxylation of Fdopa by carbidopa had taken place. When carbidopa was given intraperitoneally at a dose of 2.5 and 5 mg/kg and intravenously at 5 mg/kg, plasma carbidopa concentrations at the time of Fdopa injection were 0.95 +/- 0.26, 2.22 +/- 0.23 and 2.79 +/- 0.26 micrograms/ml, respectively. Because of inhibition of peripheral decarboxylation of Fdopa by carbidopa, more Fdopa was available for transport into the brain and as a result, both the striatal and cortical activities were significantly higher than those of the untreated monkeys. Carbidopa administration had no effect on either the striatal-to-cortical activity ratio or the striatum uptake value.

Routine determination of [18F]-L-6-fluorodopa and its metabolites in blood plasma is essential for accurate positron emission tomography studies.

A batch-contact alumina-extraction method has been used to separate [18F]-L-6-fluorodopa (FD) from its principal metabolite, 3-O-methyl-[18F]-6-fluorodopa (3-OMe-FD), in arterial blood plasma samples collected from subjects pretreated with carbidopa during positron emission tomography (PET) scans. The time course of the metabolite-corrected blood plasma activity is then used as an input function for kinetic analysis of striatal FD uptake. Results obtained from using the batch-contact alumina-extraction method were compared with those from high performance liquid chromatography, and also with those from a chromatographic alumina cartridge technique developed in this laboratory. In 60 human subjects including normal healthy volunteers and patients diagnosed as having a movement disorder, arterial blood plasma samples were collected after FD injection during a two-hour PET scan and analyzed by the batch-contact alumina-extraction method. The activity ratio (metabolites/FD) increased linearly with time for all subjects. However, there was a wide variation in the slope of the plot of the activity ratio (metabolites/FD) versus time among the subjects. No significant linear or curved relationship was observed between the slope and the age of the subject. Separation of FD from its metabolites is therefore necessary for each PET-FD study conducted.

Complex interactions of caffeine and its structural analogs with ultraviolet light in cell killing.

We measured the clonogenic survival response of cultured mouse 10T1/2 cells exposed to UV light and caffeine post-treatment. When 0.5 and 1 mM caffeine were present for 24 h immediately following UV, the D0 values of the biphasic survival curves suggest that one subpopulation was sensitized and one subpopulation was protected from killing by UV light. A cloned survivor from the radioprotected subpopulation responded to UV plus caffeine in identical manner as the parent cells. When the caffeine exposure was prolonged to 48 h, only the radiosensitizing effect was observed. Two demethylated analogs of caffeine were also tested. The response of 10T1/2 cells to 1 mM theophylline present for 24 h after UV irradiation was approximately the same as that for the same treatment with 1 mM caffeine. However, prolonging the theophylline exposure to 48 h failed to produce the same kind of potentiation of cell killing as that observed for caffeine. Xanthine by itself was as toxic to 10T1/2 cells as caffeine, but had no synergistic effect as caffeine when given to UV-irradiated cells for 24 or 48 h. It is therefore unlikely that all the effects of caffeine on UV-irradiated cells are mediated by its demethylated metabolites.

Resistance of plateau-phase human normal and xeroderma pigmentosum fibroblasts to the cytotoxic effect of ultraviolet light.

Clonogenic survival response to 254-nm ultraviolet light was measured in 2 strains of repair-proficient normal human fibroblasts and 4 strains of xeroderma pigmentosum (XP) fibroblasts belonging to complementation groups A, C, D and variant. In all strains except XPA, cells irradiated in plateau phase and subcultured immediately were much more resistant to the lethal effect of UV than cells irradiated in the exponential phase of growth. Typically, 10-20% of plateau-phase cells were extremely resistant. When the cultures were held in plateau phase for 24 h after irradiation and before subculture, there was a further enhance of survival. By use of a UV-specific endonuclease assay, no difference was found in the number of DNA lesions induced in exponentially growing and plateau cultures by the same dose of UV light. Thus plateau-phase cells appear to be more efficient in their DNA-repair capability than cells in exponential growth. XP group A cells were uniquely found to be deficient in the processes which lead to plateau-phase resistance. Since plateau-phase repair was not lacking in XP groups C, D and variant, it may be related to a DNA-repair process different from that which is responsible for the overall UV sensitivity of these cells.

Anaemia and menstrual blood loss studies in women using multiload Cu250 and progestasert IUDs.

Two to 9 months following insertion of the ML Cu250 (n = 54) and Alza T (n = 30) IUDs, mean menstrual blood losses (MBL) were 46.3 ml and 32.7 ml, respectively (p less than 0.005). Significantly more of the Alza T users had losses below 40 ml and they also perceived their menses to be lighter. Based on a haemoglobin level of 12gm/dL, the upper normal limit of MBL was about 40 ml. These findings are consistent with earlier observations that during the first year, ferritin levels fall in ML Cu250 users whereas they are unaltered in Alza T users.

PIP: 2-9 months following insertion of the Multiload Cu250 (ML Cu250; n=54) and Alza T (n=30) IUDs, mean menstrual blood loss (MBL) was 46.3 ml and 32.7 ml, respectively (p0.005). Significantly more of the Alza T users had losses below 40 ml and they also perceived their menses to be lighter. Based on a hemgloboin level of 12 gm/dL, the upper normal limit of MBL was about 40 ml. These findings are consistent with earlier observations that during the 1st year, ferritin levels fall in ML Cu250 users whereas they remain unchangeed in Alza T users.

Principles of immunosuppression.

One-year graft survival rates of 80% to 90% can now be achieved routinely for primary cadaveric transplants with a variety of CSA-containing regimens. Further improvement of these excellent results may be difficult because large numbers of patients must be evaluated to provide meaningful conclusions. On the other hand, long-term follow-up of CSA-treated patients has revealed a trend of undaunted allograft attrition with time. Future efforts therefore should be directed at improving long-term allograft results at 5 to 10 years. Further improvement of transplant outcome may be sought through better use of the currently available immunosuppressants or from newer agents. The long-term impact of CSA administration requires further evaluation. Although potent combination protocols provide effective protection against rejection, the potential development of neoplasms must be studied in long-term follow-up. On the other hand, unwarranted fear of progressive nephrotoxicity may result in underdosing of CSA and a high incidence of late rejections. The advent of mAbs has spawned an exciting era of specific immunosuppression. These newer agents may eventually help curtail the complications associated with the current regimens.

Megaloblastic anaemia--a review from University Hospital, Kuala Lumpur.

During a 5 year period, 28 adult patients with megaloblastic anaemia (MA) were treated in University Hospital. 71% of the patients were Indians. Symptoms of anaemia was the main presenting complaint in 18 (64%) of patients while in 2 patients peripheral neuropathy was the main problem. Pancytopenia was a common finding (present in 18 (64%) patients) while 6 (21%) patients had severe thrombocytopenia (less than 20 x 10(9)/L). The peripheral blood morphology provided important diagnostic clues i.e. macrocytes and/or hypersegmented neutrophils seen in most patients. Concurrent iron deficiency 'dampened' the megaloblastic picture. Though most patients suffered from MA of nutritional origin, 3 patients were diagnosed to have pernicious anaemia and 2 patients had myelodysplastic syndrome. Important practice points were detection of concurrent infection and hypokalemia which necessitated appropriate treatment. The controversy of blood transfusion in treatment of MA and the importance of reassessing patients after treatment were highlighted.