Transmission of megawatt relativistic electron beams through millimeter apertures.

High-power, relativistic electron beams from energy-recovering linacs have great potential to realize new experimental paradigms for pioneering innovation in fundamental and applied research. A major design consideration for this new generation of experimental capabilities is the understanding of the halo associated with these bright, intense beams. In this Letter, we report on measurements performed using the 100 MeV, 430 kW cw electron beam from the energy-recovering linac at the Jefferson Laboratory's Free Electron Laser facility as it traversed a set of small apertures in a 127 mm long aluminum block. Thermal measurements of the block together with neutron measurements near the beam-target interaction point yielded a consistent understanding of the beam losses. These were determined to be 3 ppm through a 2 mm diameter aperture and were maintained during a 7 h continuous run.

The ineffectiveness of reduced glutathione in preventing the development of liver tumours from aflatoxin-induced pre-neoplastic liver lesions.

Oral treatment with reduced glutathione for 10 weeks has no effect on the development of tumours from aflatoxin B1-induced gamma-glutamyl transpeptidase-positive pre-neoplastic focal lesions.

The production of carcinomas in vivo by the intravenous or subcutaneous injection of a hepatocellular tumour cell line.

Suspensions of cells of an aflatoxin-induced hepatocellular carcinoma cell line, which grow rapidly as tumours when injected subcutaneously into nude mice, have been injected subcutaneously and also intravenously via the hepatic portal or tail vein into syngeneic host animals. Efficiency of the injections was checked histologically and histochemically in parallel experimental animals. Subcutaneous injections consistently resulted in the appearance of solid tumours at the site of injection within 1 month. However, despite the apparent importance of the establishment of a blood supply when tumours are grown subcutaneously, only a low incidence of tumours (less than 20%) was detected in animals receiving intravenous injections. These results suggest that the proposed use of injection of liver cell suspensions into the portal tract as a sensitive means of detecting transformation may only be of limited value.

Characteristics of rat hepatocytes sorted by fluorescence-activated flow cytometry. Effects of mixed function oxidase inducers.

Fluorescence-activated flow cytometry has been used to separate rat liver parenchymal cells into five equal computer-generated regions on the basis of their mixed function activities towards diethoxyfluorescein. Enzymic activities in the sorted fractions showed 2.3-2.9-fold enrichment of 3-cyano-7-ethoxycoumarin O-deethylase, lactate dehydrogenase and pyruvate kinase activities in the cells of region 5. Cytochrome P-450 PBla and glutamine synthase activities were enriched 1.8- and 7-fold respectively in region 2 hepatocytes. Pretreatment of rats with phenobarbitone or 3-methylcholanthrene did not change the pattern of enrichment with respect to monooxygenase or lactate dehydrogenase activities. However, cytochrome P-450 PB3a and MC1a respectively were concentrated in the cells from region 5. In contrast, ethoxyquin caused enrichment of cytochrome P-450 in the hepatocytes in region 2. This fraction also contained the highest percentage of gamma-glutamyltranspeptidase positive cells.

Natural killer cell activity is reduced in association with oral contraceptive use.

Oral contraceptive (OC) use has been associated with increased incidence of a number of infections, but the mechanisms behind these changes is unclear. The present study compared OC users and nonusers in natural killer (NK) cell activity, NK phenotype, and illness frequency. Subjects were 55 female medical students (19 OC users, 36 nonusers). Three blood samples were obtained, 1 mo apart. Natural cytotoxicity was tested with a 51Cr assay. Self reports of illness symptoms during the previous week were collected at each blood sampling. NK phenotype number was assessed by flow cytometry. Oral contraceptive users had lower natural cytotoxicity and increased frequency of sneezing, gastrointestinal distress, runny nose, sore throat, coughing, and total illness symptoms, relative to nonusers. No differences were found between OC users and nonusers in NK phenotype number. These findings support the hypothesis that differences between users and nonusers in infection rates might be due to alterations in NK activity.

PIP: Oral contraceptive (OC) use has been associated with increased incidence of a number of infections, but the mechanisms behind such changes are unclear. Comparison of lymphocyte phenotypes between contraceptive users and nonusers found no difference in either the percentage or absolute numbers of any cell types. Other data, however, suggest differences in natural cytotoxic activity in contraceptive users. Natural cytotoxic activity in normal women has been found to vary with menstrual phase and estradiol levels, being lowest mid-cycle, shortly following peak estradiol levels. OC users, however, demonstrate no variation in either natural killer (NK) cell activity or estradiol levels over their cycles. The authors report their findings from a study comparing 19 OC users and 36 nonusers in NK cell activity, NK phenotype, and illness frequency. Three blood samples were obtained one month apart from each of the female medical student participants. Natural cytotoxicity was tested with a Cr assay, while NK phenotype number was assessed by flow cytometry. Relative to nonusers, OC users had lower natural cytotoxicity and increased frequency of sneezing, gastrointestinal distress, runny nose, sore throat, coughing, and total illness symptoms. No differences were found between OC users and nonusers in NK phenotype number. These findings support the hypothesis that differences between users and nonusers in infection rates may be due to alterations in NK activity.

Economic outcomes with antidepressant pharmacotherapy: a retrospective intent-to-treat analysis.

Herein we describe a retrospective intent-to-treat evaluation designed to compare the natural course of antidepressant utilization and direct health service expenditures for the treatment of a single episode of major depression among patients enrolled in a multistate network-model health maintenance organization and initially prescribed either a tricyclic antidepressant (amitriptyline or nortriptyline) or the serotonin selective reuptake inhibitor (SSRI) fluoxetine. Patient-level paid-claims data for the period July 1, 1988, through December 31, 1991, were abstracted. During the above time frame, fluoxetine was the only SSRI available in the United States. Patients prescribed amitriptyline were more than three times as likely to require a change in antidepressant pharmacotherapy (OR = 3.27, 95% CI = 2.31 to 5.49), while patients prescribed nortriptyline were nearly four times more likely to change medication (OR = 3.82, 95% CI = 2.74 to 6.83) relative to patients initially prescribed fluoxetine. Consistent with our intent-to-treat design, all accrued health service expenditures were assigned to the pharmacotherapeutic option initially prescribed. Multivariate analyses revealed that initiation of antidepressant pharmacotherapy with amitriptyline resulted in a 25.7% increase in per capita depression-related health service expenditures per year, while initiation of antidepressant pharmacotherapy with nortriptyline resulted in a 28.1% increase in per capita depression-related health service expenditures per year relative to patients initially prescribed fluoxetine. A financial break-even point was achieved at the conclusion of Month 5, at which time all three intent-to-treat cohorts had comparable health service expenditures in total. From a financial perspective, results stemming from this inquiry suggest that the initiation of antidepressant pharmacotherapy with an SSRI is warranted.

Ipratropium bromide in the management of chronic obstructive pulmonary disease: effect on health service expenditures.

Chronic obstructive pulmonary disease (COPD), which is estimated to affect 32 million Americans, is the fifth leading cause of death in the United States. This retrospective study was designed to discern the economic utility of initial pharmacotherapy with various individual drugs in the management of COPD, as well as subsequent costs incurred as disease progression necessitated combination therapy. Data for this analysis were derived from the computer archive of a network-model health maintenance organization. During the first 6 months post-diagnosis for COPD, results indicated a significant (P < or = 0.05) increase in expenditures for physicians, hospital care, and total health service utilization for patients prescribed theophylline, a corticosteroid (triamcinolone or beclomethasone) delivered via a metered-dose inhaler, or albuterol delivered via a metered-dose inhaler as initial monotherapy compared with patients prescribed ipratropium bromide (IB) delivered via a metered-dose inhaler. Patients receiving initial pharmacotherapy with ipratropium bromide and subsequently adding albuterol used significantly less health care services (P < or = 0.05) during the first 15 months post-diagnosis for COPD than did patients prescribed all other combination therapies we evaluated.

Antidepressant pharmacotherapy: economic outcomes in a health maintenance organization.

Recent pharmacotherapeutic advances in the treatment of depression have included the development of selective serotonin re-uptake inhibitors (SSRIs). The present study was designed to contrast direct health service expenditures for the treatment of depression among patients enrolled in a health maintenance organization (HMO) and prescribed either the SSRI fluoxetine or one of three tricyclic antidepressants (TCAs) (amitriptyline, nortriptyline, or desipramine). Information regarding health service utilization was derived from the computer archive of a network-model HMO system serving 400,000 beneficiaries. A total of 701 HMO beneficiaries were found to satisfy the study selection criteria. Multivariate regression analysis was used to discern the incremental influence of selected demographic, clinical, financial, and provider characteristics on 1 year post-period expenditures (PPE) for health care. Analysis-of-variance procedures with Duncan's multiple-range test, or chi-square analyses, revealed no significant difference across antidepressant pharmacotherapy for age, sex, 6-month prior-period expenditures for physician visits, psychiatric visits, laboratory tests, hospitalizations, or psychiatric hospital services related to the treatment of depression, or number of prescribed therapeutic agents for disease state processes other than depression. Receipt of fluoxetine was associated with a significantly (P < or = 0.05) higher rate of initial prescribing by psychiatrists, an increase in the number of prescriptions for antidepressant pharmacotherapy obtained (30-day supplies), and a reduction in the number of monthly intervals during which time antidepressant pharmacotherapy was not procured. Receipt of fluoxetine as antidepressant pharmacotherapy was associated with a significantly (P < or = 0.05) higher mean medication possession ratio (MPR) relative to amitriptyline, nortriptyline, or desipramine. Multivariate findings for patient-level data reflecting a definitive diagnosis of depression (n = 555) indicate that receipt of a TCA resulted in a significant (P < or = 0.05) increase in the use of physician visits ($36.07), psychiatric visits ($41.38), laboratory tests ($1.71), hospitalizations ($208.77), and psychiatric hospital services ($187.27), and a significant (P < or = 0.05) reduction in expenditures for antidepressant pharmacotherapy (-$162.21), for a total increase in health service utilization of $312.99 (P < or = 0.05) 1 year post-initiation of antidepressant pharmacotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Antimitotic activity of dehydroretronecine, a pyrrolizidine alkaloid metabolite, and some analogous compounds, in a rat liver parenchymal cell line.

The actions of 13 pyrrolic alcohols with similar chemical properties have been tested on cultured liver cells. Two, dehydroretronecine and dehydrosupinidine, were putative metabolites of hepatotoxic pyrrolizidine alkaloids; the remainder were synthetic. All were either mono- or bi-functional alkylating agents. Groups of cells were exposed to the compounds and were later stimulated to divide by changing the medium, then fixed, stained, and the proportions of cells in mitosis counted and compared with those in similarly treated control cells. Eleven compounds partially or completely inhibited cell division at concentrations of 10(-4) M or less. Bifunctional compounds, including dehydroretronecine and 2,3-bis-hydroxymethyl-1-methylpyrrole, had the highest antimitotic activity coupled with lowest cytotoxicity. The least chemically reactive compound, 3-hydroxymethyl-1-methylpyrrole, was neither antimitotic nor cytotoxic, whereas the monofunctional alkylating agents with highest reactivity, such as 3-hydroxymethyl-1,2-dimethylpyrrole, were the most toxic to the cells. The mitotic block occurred at a post-synthetic stage of the cell cycle, and affected cells could grow to a giant size.

Trapping of short-lived electrophilic metabolites of pyrrolizidine alkaloids escaping from perfused rat liver.

It has been shown that a short-lived pyrrolic metabolite in fluid flowing out of isolated rat liver perfused with the pyrrolizidine alkaloid, monocrotaline, could be trapped by covalent reaction with a bed of immobilized thiol (thiol-sepharose). Larger amounts of other pyrrolic metabolites, also in the fluid, were not trapped. This provided the first direct support for the widely held hypothesis that reactive pyrrolizidine alkaloid metabolites (dehydro-alkaloids) escape from the liver to damage the lungs of rats in vivo. The relatively smaller proportion of pyrrolic metabolite from retrorsine which could be trapped in this way was consistent with the known lack of pneumotoxicity of this alkaloid. The procedure described should be suitable for trapping other types of electrophilic metabolites.

Cost-effectiveness of sumatriptan in a managed care population.

We conducted an open-labeled study to determine whether sumatriptan is more cost-effective than other therapies used to treat migraine headache. We contacted by phone 220 sumatriptan users enrolled in QualMed, a health maintenance organization (HMO) in Spokane, Washington. Of these, 203 met the inclusion criteria and 164 (81%) completed our telephone survey. The main outcome measures were healthcare costs to the HMO and number of days free of migraine-related disability before and after sumatriptan treatment. Before sumatriptan treatment, 89% of patients reported severe migraine, compared with 63% after sumatriptan treatment. The number of monthly migraine disability days decreased from 6.5 days per month before sumatriptan to 3.9 days per month after sumatriptan. Healthcare utilization rates (ie, number of hospitalizations, emergency department visits) and costs were lower after the patients began taking sumatriptan. The number of different over-the-counter medicines and prescription medications (other than sumatriptan) taken for migraine disabilities decreased. Although total drug expenditures per month increased, the total migraine healthcare expenditure was 41% lower after sumatriptan was initiated. The cost-effectiveness ratio was 47% more favorable after patients started taking sumatriptan. Overall, patients reported fewer migraine-related disabilities, had lower migraine severity scores, and used fewer healthcare resources when taking sumatriptan. These changes resulted in a better cost-effectiveness ratio for migraine treatment.

Cost benefit of sumatriptan to an employer.

Benefit and occupational health managers need information on whether new treatments, such as sumatriptan, for migraine headache improve organizational or individual performance. A work productivity outcomes assessment was conducted among sumatriptan-using employees of an Independent Practice Association-health maintenance organization population. Of the 164 sumatriptan users, 101 full-time employees were surveyed by telephone once in an open-label, before-after design. The results revealed that lost labor costs, a function of days missed from work and reduced productivity at work as a result of migraine, were decreased after sumatriptan treatment initiation. Incremental benefit of this reduction in lost productivity is valued at $435/month per employee. The sumatriptan cost associated with this benefit is $43.78/month. The benefit-to-cost ratio is 10:1. Other costs and benefits were excluded. In conclusion, the availability of sumatriptan for migraine headache treatments in this IPA-HMO resulted in improved work productivity and had a net benefit for the employer.

Antidepressant pharmacotherapy: economic evaluation of fluoxetine, paroxetine and sertraline in a health maintenance organization.

The present study was designed to compare direct health service expenditures, for the treatment of depression, among patients enrolled in a health maintenance organization, and prescribed one of three selective serotonin reuptake inhibitors, fluoxetine, paroxetine or sertraline. Information regarding depression-related health service use was derived from the computer archive of a network-model health maintenance organization system serving 700,000 beneficiaries. A total of 744 health maintenance organization beneficiaries were found to satisfy the study selection criteria. Multivariate regression analysis was used to determine the incremental influence of selected demographic, clinical, financial and provider characteristics on health service expenditures related to the treatment of depression (ICD-9-CM, or DSM-IV code 296.2) 1 year after the start of antidepressant pharmacotherapy. Multivariate findings indicate that treatment with paroxetine increases average expenditures for physician visits ($31.93; P < or = 0.05), psychiatric visits ($19.33; NS), laboratory tests ($2.35; P < or = 0.05), hospitalizations ($85.33; P < or = 0.05), psychiatric hospitalizations ($82.01; P < or = 0.05), and antidepressant pharmacotherapy ($63.72; P < or = 0.05), for a total per capita increase in health service use of $284.68 (P < or = 0.05), compared with treatment with fluoxetine. Sertraline treatment increases average expenditures for physician visits ($21.74; P < or = 0.05), psychiatric visits ($56.79; P < or = 0.05), laboratory tests ($1.21; P < or = 0.05), hospitalizations ($70.59; P < or = 0.05), psychiatric hospitalizations ($95.75; P < or = 0.05), and antidepressant pharmacotherapy ($69.85; P < or = 0.05), for a total per capita increase in health service use of $315.96 (P < or = 0.05), compared with treatment with fluoxetine. Economic comparisons between paroxetine and sertraline did not demonstrate any significant differences in expenditures for the health services examined.

Mouse strain differences in resident peritoneal cells: a flow cytometric analysis.

A flow-cytometric study of resident peritoneal cells among 8 mouse strains showed a more than twofold variation in the ratio of macrophages to macrophages plus lymphocytes, ranging from 27% in A/J to 62% in C57B/L10, with significant strain differences in a number of other cellular parameters. There was a particular deficiency of lymphocytes in strain CBA/N, which carries the xid mutation. Studies of the phagocytosis of fluorescent beads also revealed large differences in the number of beads taken up, ranging from 0.99 per cell in MFI to 1.64 per cell in BALB/c mice in a 20-min period. The total number of peritoneal cells collected also varied between strains, ranging from 2.75 x 10(6) in CBA/Ca to 5.85 x 10(6) in MF1. The total yield of macrophages per mouse ranged from 0.93 x 10(6) in A/J to 3.16 x 10(6) in C57BL/10. These differences should be taken into account when designing experiments which use resident peritoneal cells.

Fluorescence-activated sorting of rat hepatocytes based on their mixed function oxidase activities towards diethoxyfluorescein.

The formation of ethoxyfluorescein and fluorescein from diethoxyfluorescein by isolated rat hepatocytes has been used as a basis for separating such cells dependent on their mixed function oxidase activities by fluorescence-activated flow cytometry. Five equal fractions defined by computer-generated regions were isolated. Non-viable cells with low fluorescence (region 1) represented 10-15% of the population, while the remainder with higher mixed function oxidase activities (regions 2-5), were greater than 95% viable by Trypan Blue exclusion. In region 1, 30% of the viable cells were binucleate, 67% diploid while in region 5, 13% were binucleate and 69% tetraploid. At 3 h after sorting, following attachment to glass coverslips, exposure of cells to methyl methanesulphonate, retrorsine or norethindrone resulted in unscheduled DNA synthesis which was 2-fold higher in the tetraploid-rich region 5, while aflatoxin B1, benzo[a]pyrene or 2-acetylaminofluorene caused a 5-fold increase in unscheduled DNA synthesis in these cells, relative to the diploid-rich hepatocytes in region 2.

The role of lymphocyte production and migration in the lymphopenia caused by 2-acetyl-4-tetrahydroxybutyl imidazole.

2-Acetyl-4-tetrahydroxybutyl imidazole (THI), a component of the food colouring ammonia caramel, has been shown to produce a profound and rapid lymphopenia in peripheral blood in the rat. In order to investigate whether the cause of the lymphopenia was due to the reduced production and influx in the circulation, redistribution of lymphocytes into other lymphoid compartments or an increased cell death, THI (1 mg/kg/day) was given in the drinking water for up to 14 days to F344 rats. A profound depletion of lymphocytes after already 1 day was only found in the blood compartment, whereas no such marked and rapid changes were found in the cellularity of other lymphoid compartments. The proportion and absolute number of DNA-synthesizing cells in each lymphoid organ was quantified using an antibody directed against incorporated 5-bromo-2'-deoxyuridine (BrdU), 1 h after a single BrdU injection. Additionally, enumeration and localization of BrdU+ cells was determined at later time points after a single BrdU injection by flow cytometry and immunocytochemistry, in order to examine the distribution and localization of recently formed (BrdU+) lymphocytes. THI treatment had no effect on the proliferation rate and the distribution of newly formed (BrdU+) cells in the lymphoid organs. However, migration studies revealed that THI treatment resulted in an increased percentage of fluorescein-labelled peripheral blood lymphocytes found in the spleen and bone marrow and a decreased percentage in the cervical and mesenteric lymph nodes, 24 h after injection. Collectively these results indicate that the lymphopenia in the peripheral blood compartment after THI treatment, is caused by a rapid sequestration of lymphocytes into the spleen and bone marrow rather than by a reduced lymphocyte production and release into the periphery. The fact that THI also caused lymphopenia in splenectomized rats, indicates that the spleen does not play an active part in the change in migrational behaviour of lymphocytes after THI treatment. Finally, as there was no increase in the absolute number of lymphocytes found in the spleen or bone marrow it seems they are rapidly degraded.

Specific G1-S phase cell cycle block by beryllium as demonstrated by cytofluorometric analysis.

Inhibition of cell division by beryllium (Be2+) has been examined in synchronized cultures of a liver-derived cell line (BL9L cells) using cytofluorometric cell cycle analysis. Results show that a selective dose-related block of the G1-pre-S transition is produced, with other periods of the cell cycle appearing relatively insensitive.

Relationship between the ability of nicotinamide to maintain nicotinamide-adenine dinucleotide in rat liver cell culture and its effect on cytochrome P-450.

Rat hepatocytes cultured for 24 h lose 60% of their NAD content. Treatment with nicotinamide prevents the loss of NAD as well as the previously reported loss of cytochrome P-450, suggesting a possible causal relationship. However, isonicotinamide also prevents the loss of cytochrome P-450, but does not increase the concentration of NAD, demonstrating that the ability of nicotinamide to maintain cytochrome P-450 is not apparently related to its effect on the NAD content of cultured hepatocytes.

Sensitivity of the cell cycle to TGF beta 1 does not correlate with transformation of a rat liver epithelial cell line.

The effects of TGF beta 1 on cell cycle events in a rat liver derived epithelial cell line (BL9) and in two in vitro transformants of this line were studied by flow cytometry. Using either ethidium bromide staining or the incorporation of bromodeoxyuridine to evaluate DNA synthesis it was shown that TGF beta 1 prevented the entry of G0/G1 phase BL9 cells into S phase. TGF beta 1 did not exert its inhibitory effect(s) on DNA synthesis by the modulation of early events in the cell cycle. The tumorigenic transformed BL9 cell lines gave contrasting responses to the effects of TGF beta 1. DNA synthesis in a BL9 cell line derived by transfection with an active N-ras oncogene was unaffected by TFG beta 1 and thus appeared refractory to its growth controlling effects. On the other hand cells from a BL9 cell line derived by in vitro transformation with activated aflatoxin B1 retained their sensitivity to the effects of TGF beta 1. Thus the loss of the inhibitory effect of TGF beta 1 on DNA synthesis is not obligatory for the malignant transformation of rat liver epithelial cells.