Multiplexed Assays by High-Content Imaging for Assessment of GPCR Activity

G-protein-coupled receptors (GPCR) participate in many disease pathways and represent the largest family of therapeutic targets. Thus, great investments are made to discover drugs modulating GPCR-mediated events. Among functional assays for screening GPCRs, the Transfluor®imaging assay is based on redistribution of cytosolic β-arrestin to an activated GPCR and has become widely used in high-content screening. However, assessing Transfluor®alone has limitations: relying on a single mechanistic step of β-arrestin redistribution during GPCR activation, providing no information on the stimulated GPCR's intracellular fate, and using only a single fluorescent color (green fluorescent protein). Taking full advantage of high-content imaging to screen approximately 2000 compounds, the authors multifplexed the Transfluor®assay with an immunofluorescence-based quantification of GPCR internalization. This approach identified and classified 377 compounds interfering with agonist-induced activation of the Transfluor®assay, receptor internalization, or both. In addition, a subset of compounds was analyzed for their performance across imaging, cell-based calcium release (fluorometric imaging plate reader [FLIPR]), and biochemical receptor binding assays (scintillation proximity assay). This indicated that the imaging assays have even better predictive power for direct inhibition of receptor binding than the FLIPR assay. In conclusion, compounds inducing unique responses can suggest novel mechanisms of action and be used as tools to study GPCR activation and internalization. ( Journal of Biomolecular Screening 2008:449-455)

A clinical and pharmacokinetic trial of six doses of artemether-lumefantrine for multidrug-resistant Plasmodium falciparum malaria in Thailand

The efficacy-safety and pharmacokinetics of the six-dose regimen of artemether-lumefantrine (Coartem/Riamet; Novartis Pharma AG, Basel, Switzerland) were assessed in a randomized trial in 219 patients (> or = 12 years old) with acute, uncomplicated Plasmodium falciparum malaria in Thailand. One hundred and sixty-four patients received artemether-lumefantrine and 55 received the standard treatment combination of mefloquine-artesunate. Both drugs induced rapid clearance of parasites and malaria symptoms. The 28-day cure rates were 95.5% (90% confidence interval [CI] = 91.7, 97.9%) for artemether-lumefantrine and 100% (90% CI = 94.5, 100%) for mefloquine-artesunate. This high-dose regimen of artemether-lumefantrine was very well tolerated, with very good compliance. The most frequent adverse events were headache, dizziness, nausea, abdominal pain, dyspepsia, vomiting, and skin rash. Overall, only 2% of patients in both groups showed QTc prolongations but without any cardiac complication, and no differences were seen between patients with and without measurable baseline plasma levels of quinine or mefloquine. Plasma levels of artemether, dihydroartemisinin, and lumefantrine were consistent with historical data for the same dose regimen, and were higher, particularly for lumefantrine, than those previously observed with the four-dose regimen, explaining the greater efficacy of the six-dose regimen in a drug-resistant setting. These results confirm the excellent safety and efficacy of the six-dose regimen of artemether-lumefantrine in the treatment of multidrug-resistant P. falciparum malaria.

The efficacy and tolerability of triclabendazole in Cuban patients with latent and chronic Fasciola hepatica infection

Current chemotherapy for the treatment of infections caused by the liver fluke Fasciola hepatica is not satisfactory. Therefore, the efficacy and tolerability of triclabendazole (TCZ) was assessed for this indication. Eighty-two patients (51 female, 31 male, age 15-81 yr, mean 42 yr) with chronic or latent F. hepatica infection refractory to previous anti-helminthic chemotherapy were enrolled in a 60-day open, non-comparative trial. Patients received 20 mg/kg TCZ as two doses of 10 mg/kg administered after food 12 hr apart. Efficacy of treatment was assessed by stool microscopy, determination of Fasciola excretory-secretory antigen (FES) in feces, and by ultrasonography (US) which were systematically performed pre-therapy and on Days 1-7, 15, 30, and 60 post-therapy. For continuous safety assessment, patients were hospitalized during the first week after therapy and then monitored at home for the appearance of any adverse events. Clinical chemistry and hematology tests were carried out on Days 1, 3, 7, 15, and 60, and whenever an adverse effect occurred possibly related to therapy. Seventy-one (92.2%) of the 77 patients who completed the 60-day follow-up period became egg-negative. Efficacy of therapy was supported by the disappearance or decrease of FES antigen and of ultrasonography abnormalities. In the 6 remaining patients, parasitological cure was achieved by another single TCZ dose of 10 mg/kg on Day 60. A total of 74 adverse events possibly related to therapy was reported by 54 patients. The most important adverse event was colic-like abdominal pain (40 patients [49%]) consistent with the expulsion of the parasite through the bile ducts as confirmed by US on Days 2-7. Most adverse events (53) were graded as mild, 20 as moderate, and only 1 as severe (a biliary colic responding to spasmolytic therapy within two hours). Triclabendazole 20 mg/kg is an effective therapy for the treatment of F. hepatica infection in patients who have failed to respond to other antihelminthic agents. Biliary colics reflecting the expulsion of dead or damaged parasites usually occur during Day 3-7 and respond well to spasmolytic therapy.

Artemether-lumefantrine for the treatment of multidrug-resistant falciparum malaria

The efficacy and safety of the 6-dose regimen of artemether-lumefantrine were assessed in an open randomized trial in children and adults presenting with acute, uncomplicated Plasmodium falciparum malaria in Thailand between November 1997 and March 1998. 200 patients were enrolled in 2 centres: 150 received artemether-lumefantrine (i.e., a median total dose of 9.6 mg/kg [interquartile range 8.7-10.7] and 57.9 mg/kg of lumefantrine [52.4-64.0]) and 50 the standard combination of artesunate (12 mg/kg over 3 d) and mefloquine (25 mg/kg). All patients had rapid initial clinical and parasitological responses. The 28 d cure rates were high: 97.7% (95% confidence interval [95% CI] 93.5-99.5%) for artemether-lumefantrine and 100% (95% CI 92.5-100%) for artesunate-mefloquine. The 6-dose regimen of artemether-lumefantrine was better tolerated than, and as effective as, artesunate-mefloquine, the current standard treatment in this area of multidrug-resistant P. falciparum malaria.

Pharmacokinetics of benflumetol given as a fixed combination artemether-benflumetol (CGP 56697) in Thai patients with uncomplicated falciparum malaria

The pharmacokinetics of benflumetol as a fixed combination, artemether-benflumetol (CGP 56697), following three regimens [regimen A: four tablets at 0, 8, 24 and 48 h (320 mg artemether, 1,920 mg benflumetol); regimen B: two tablets at 0, 8, 24 and 48 h (160 mg artemether, 960 mg benflumetol); regimen C: four tablets at 0, 8 and 24 h (240 mg artemether, 1,440 mg benflumetol)] were investigated in 39 patients with acute uncomplicated falciparum malaria. All patients showed a rapid initial response with a median parasite clearance time of 40, 41 and 39.5 h and a fever clearance time of 27.8, 32 and 24.5 h for regimens A, B and C, respectively. In nine patients (two, four and three patients in regimens A, B and C, respectively), however, parasitemia reappeared in the peripheral blood smear between days 9 and 23. The pharmacokinetics of benflumetol were highly variable, with coefficients of variation in pharmacokinetic parameters ranging from 14.9% to 144%. Absorption and elimination of benflumetol were relatively slow. Median Cmax per dose (first dose) was significantly higher in regimen B (6.29 ng/ml/mg dose) than in regimen A (2.6 ng/ml/mg dose) and regimen C (3.06 ng/ml/mg dose). Mean T1/2z in regimen C (2.65 h) was significantly shorter than in regimen A (4.5 h) and regimen B (3.89 h). In patients on regimens A and B who showed a sensitive response, plasma concentrations of benflumetol were significantly higher than in those with treatment failure.

A randomized, double-blind, parallel-group, comparative safety, and efficacy trial of oral co-artemether versus oral chloroquine in the treatment of acute uncomplicated Plasmodium falciparum malaria in adults in India

In India, treatment of acute, uncomplicated Plasmodium falciparum malaria is becoming increasingly difficult due to resistance to chloroquine, thus there is a need for new antimalarial drugs. CGP 56697 (co-artemether), a new drug, is a combination of artemether and lumefantrine in a single oral formulation (one tablet = 20 mg of artemether plus 120 mg of lumefantrine). In a double-blind study, 179 patients with acute uncomplicated P. falciparum malaria were randomly assigned to receive either CGP (n = 89) given as a short course of 4 x 4 tablets over a 48-hr period or chloroquine (n = 90) given as four tablets (one tablet = 150 mg of chloroquine base) initially, followed by two tablets each at 6-8, 24, and 48 hr. Due to a death in the chloroquine group and a decrease in the chloroquine cure rate to < 50% (based on the blinded overall cure rate at that time), recruitment was terminated prematurely. CGP 56697 showed a superior 28-day cure rate (95.4% versus 19.7%; P < 0.001), time to parasite clearance (median = 36 versus 60 hr; P < 0.001), and resolution of fever (median = 18 versus 27 hr; P = 0.0456). This drug provides a safe, effective, and rapid therapy for the treatment of acute uncomplicated P. falciparum malaria.

Fascioliasis: sonographic abnormalities of the biliary tract and evolution after treatment with triclabendazole

Diagnosis of infection with the liver fluke Fasciola hepatica is usually difficult. Ultrasonography (US) might be a useful diagnostic alternative, and we assessed the value of sequential US in the diagnosis and monitoring of fascioliasis in 76 patients at baseline and for 60 days after treatment with triclabendazole. At baseline, biliary abnormalities were observed in 52 patients. Crescent-shaped parasites were seen in 11 patients; in 2 cases parasites were spontaneously moving and in 4 patients parasites were motionless. Postprandial examination revealed parasites adhering to the gallbladder wall in a further 5 cases. In 3 further cases, gallbladder contents were mobile but did not sediment downwards after patients changed position. Non-specific abnormalities were: impaired gallbladder contractility (n = 23), gallbladder tenderness (n = 19), debris (n = 6), calculi (n = 5), wall thickening (n = 2) and bile duct dilatation (n = 12). During day 1-7, Fasciola-like crescents in the gallbladder or passing through the bile duct were detected in another 15 patients, impaired gallbladder contractility in 16, gallbladder tenderness in 16, and bile duct dilatation in an additional 28 patients. Thirty-two patients with these US abnormalities experienced colic-like abdominal pain accompanied by increased alkaline phosphatase in 25 cases. During day 30-60, abnormalities regressed completely in 45 patients; 2/6 triclabendazole failures were evident by detection of living parasites. Biliary tract abnormalities are frequently observed by US, but the detection-rate of Fasciola hepatica is disappointingly low despite the parasite's relatively large size. US findings must therefore be interpreted together with other clinical measurements. The visualization of parasites being expelled through the dilated common bile duct allowed the causal interpretation of post-therapeutic abdominal pain and increase of liver enzymes. When triclabendazole is given on suspicion, visualization of worm expulsion and bile duct dilatation by US may be used to confirm diagnosis.

Multiple dose pharmacokinetics of artemether in Chinese patients with uncomplicated falciparum malaria

Multiple dose pharmacokinetics of artemether and dihydroartemisinin were investigated in chinese patients treated for malaria. They received over 2 days either 4 x 80 mg artemether orally (n = 48) or 4 x 80-480 mg co-artemether (n = 40), a combination of artemether and lumefantrine (benflumetol). Lag time = 0.48 h (mean), Cmax after first dose = 157 ng/ml, t(max) = 1.73 h and elimination half-life = 1.16 h. The lag and absorption times were 0.5 h longer for co-artemether compared with artemether. Dihydroartemisinin paralleled artemether pharmacokinetics. Artemether Cmax after the last dose was one-third of the Cmax after the first dose while, inversely, dihydroartemisinin Cmax increased over time. We suggest that auto-induction of gut mucosa enzymes and/or liver enzymes causes a time-dependent increase in first-pass metabolisation of artemether.

The comparative efficacy and tolerability of CGP 56697 (artemether + lumefantrine) versus halofantrine in the treatment of uncomplicated falciparum malaria in travellers returning from the Tropics to The Netherlands and France

CGP 56697 (Riamet) is a new oral anti-malarial drug composed of artemether and lumefantrine (benflumetol) which combines the fast, short-acting artemether for rapid parasite clearance with the prolonged action of lumefantrine for intended radical cure. In this double-blind, comparative trial, the efficacy and tolerability of CGP 56697, given as a course of 4 x 4 tablets over 48 h, was compared to halofantrine, given as 3 x 2 tablets over 12 h with a second course 1 week later. Patients (mostly non-immune) with acute, uncomplicated Plasmodium falciparum infection were randomly assigned to either CGP 56697 (n = 51) or halofantrine (n = 52). CGP 56697 proved superior with respect to parasite clearance time (median 32 vs. 48 h, P < 0.001) and parasite reduction at 24 h (median 99.7 vs. 89.6%, P < 0.001) with a non-significant difference in resolution of fever (median 24 vs. 32 h, P = 0.835). However, a 28-day cure rate of 82% was observed for CGP 56697 and 100% for halofantrine. Significant QTc prolongations (> 30 ms) were seen 6-12 h after halofantrine intake but not after CGP 56697 intake. CGP 56697 is an effective, well-tolerated treatment for uncomplicated falciparum malaria but for this dosing regimen the recrudescence rate is unacceptablyhigh (18%). For travellers contracting malaria abroad, we propose a six-dose regimen of CGP 56697 over 3 days.

Positioning, labelling, and medical information control of co-artemether tablets (CPG 56697): a fixed novel combination of artemether and benflumetol. Novartis Co-Artemether International Development Team

Coartemether is a fixed 1:6 ratio of artemether and lumefantrine (benflumetol), a joint development between Novartis Pharma and the Academy of Military Medical Sciences (Beijing, China). It is well tolerated and has a high efficacy against uncomplicated and drug resistant falciparum malaria by oral administration. The preclinical profile of coartemether revealed no prohibitive toxicological, teratogenic or mutagenic findings. No evidence of neurotoxicity was seen in oral preclinical studies. It shows a negative response to the induction of resistance and prevents recrudescence. Clinically, coartemether shows a rapid onset of antiparasitic action, resolution of symptoms, no clinical neurotoxicity and excellent parasite clearance.

Population pharmacokinetics and therapeutic response of CGP 56697 (artemether + benflumetol) in malaria patients

AIMS

To investigate the pharmacokinetic and pharmacodynamic properties of artemether and benflumetol in a fixed combination tablet (CGP 56697) and to offer an explanation for the lower than expected cure rate in a Thai clinical trial.

METHODS

Two hundred and sixty patients were enrolled into a randomized, double-blind, parallel group, dose-finding trial. CGP 56697 was given orally, either as: A, 4 x 4 tablets over 48 h; B, 4 x 2 tablets over 48 h or C, 3 x 4 tablets over 24 h. Each tablet contained artemether 20 mg amd benflumetol 120 mg. The pharmacokinetics were determined using a population-based approach combining full profiles (42 patients) and sparse data (218 patients). Parasite clearance time and 28 day cure rate were correlated with the derived pharmacokinetic parameters.

RESULTS

The median absorption half-life of benflumetol was 5.3 h, with a tmax of 10 h and terminal elimination half-life of 4.5 days. For artemether (and its metabolite, dihydroartemisinin), the corresponding values were 1.9 (1.9) h, 1.8 (1.2) h, and 0.84 (0.43) h. The variability in bioavailability of artemether and dihydroartemisinin was large both between doses and between patients, but was less pronounced for benflumetol. Compared with the first dose, benflumetol bioavailability was estimated to increase three-fold by the third and fourth doses. Higher artemether or dihydroartemisinin AUC was found to decrease parasite clearance time. Higher benflumetol AUC was found to significantly increase the chance of cure.

CONCLUSIONS

Using a population-based approach it was confirmed that the pharmacokinetic and pharmacodynamic properties of benflumetol and artemether differ markedly. Benflumetol AUC is associated with cure and the effect of benflumetol when coadministered with artemether is to prevent recrudescence. The mode of action of benflumetol is consistent with its longer elimination half-life. A short course of low-dose artemether, which is rapidly absorbed and has a short elimination half-life, produced effective parasite clearance. The complementary pharmacokinetic and pharmacodynamic properties of benflumetol and artemether was the main rationale for developing a fixed-dose combination. While the 4 x 4 dose regimen is very effective in most endemic areas, the poorer absorption (2.5 fold lower than in China) and the more resistant parasites in Thailand require higher doses of this drug.

Distinction of recrudescences from new infections by PCR-RFLP analysis in a comparative trial of CGP 56 697 and chloroquine in Tanzanian children

OBJECTIVE

To test the efficacy of a new compound drug (CGP 56697) against acute, uncomplicated falciparum malaria.

METHOD

Reappearing parasites were analysed by PCR-RFLP within a randomized controlled trial. 130 patients received chloroquine and 130 patients were treated with CGP 56697. Samples from 96 patients with parasitological failure were tested by PCR-RFLP for MSP2 of Plasmodium falciparum. Seven days after treatment 32 patients of the chloroquine control group with reappearing parasites were tested by PCR and one infection was unequivocally determined as a new infection. After 7 days, in the CGP 56697 group, 6 samples were tested in which one new infection was identified. Similar observations were made one and three weeks later in both groups.

RESULTS

Although a high multiplicity of infections on admission was observed, there was no significant correlation between multiplicity and either recrudescence or new infection. Patients in both treatment groups with subsequent recrudescent parasites had higher initial mean parasite densities than patients who cleared. Those of the patients with recrudescent parasites who were treated with CGP 56697 had higher initial parasite densities than those treated with chloroquine. The rate of re-infection increased with time as expected in holoendemic areas and appeared to be higher in chloroquine patients. Generally, CGP 56697 showed a superior clearance rate, successfully cleared higher parasite densities and suppressed new infections over a longer period of time.

CONCLUSION

The PCR analysis confirmed that reinfections beyond day 7 are significant in areas highly endemic for malaria and showed the necessity of excluding these when estimating 14 day clearance rates. Provided new infections are excluded, the 28-day clearance rate can also be used to determine the efficacy of antimalarial drugs in highly endemic areas, and adds to our knowledge of drug resistance and dynamics of infections in people living in such areas.

Effect of food on the bioavailability of triclabendazole in patients with fascioliasis

AIMS

Preliminary results indicate higher absorption of triclabendazole (TCBZ) administered postprandially. Therefore, the influence of food on the pharmacokinetics of TCBZ and its active sulphoxide (TCBZ-SO) and sulphone (TCBZ-SO2) metabolites was investigated.

METHODS

Two single doses (10 mg kg(-1)) of TCBZ were administered to 20 patients with fascioliasis. Ten patients were first given the drug after a high energy breakfast and then, 48 h later, after an overnight fast. The other 10 patients first received the drug in fasting state and then, 48 h later, after breakfast. A low energy breakfast was served 2 h after drug administration for fasting state.

RESULTS

Compared with the fasting state, an increased AUC and Cmax after food intake (significant, P < 0.0001) was shown from the values of TCBZ, TCBZ-SO and TCBZ-SO2. The mean AUC for TCBZ (fasting: 1.55, fed: 5.72 micromol l(-1) h), TCBZ-SO (fasting: 177, fed: 386 micromol l(-1) h) and TCBZ-SO2 (fasting: 13.9, fed: 30.5 micromol l(-1) h) indicated a large availability increase with food and the strong systemic predominance of the active sulphoxide metabolite over the unchanged drug. (All patients were cured at the end of the trial except one who required a second course of two postprandial doses of triclabendazole (10 mg kg(-1) each). Tolerability to the treatment among the patients was good.

CONCLUSIONS

The administration of triclabendazole with food is recommended for improved systemic availability in patients with fascioliasis or paragonimiasis.

Efficacy and safety of CGP 56697 (artemether and benflumetol) compared with chloroquine to treat acute falciparum malaria in Tanzanian children aged 1-5 years

A randomized, open trial involving 260 Tanzanian children, aged 1-5 years, with acute Plasmodium falciparum malaria was conducted to evaluate the efficacy of the combination antimalarial CGP 56697 (artemether and benflumetol), and to compare it with chloroquine, the standard drug used for malaria treatment in the Kilombero area. Children who had received rescue medication within the first 48 h or had a negative slide at the same time were excluded. Seven-day parasitological cure rates were 94% (95% CI 88-97.5) for CGP 56697 and 35.4% (95% CI 25.9-45.8) for chloroquine. Using the same definition, the 14-day parasitological cure rates were 86.4% (95% CI 78.5-92.2) for CGP 56697 and 10.3% (95% CI 5.1-18.1) for chloroquine. Gametocytes were more effectively suppressed by CGP 56697 than by chloroquine. There were no major adverse events with either drug. CGP 56697 is highly efficacious against P. falciparum in this area of Tanzania. The study contributes to the discussion on treatment strategies, particularly whether chloroquine may still fulfil its role as first-line drug in an area of high malaria transmission and very high levels of chloroquine resistance.

Cardiac transplant donor heart allocation based on prospective tissue matching

The present priority scheme for the allocation of donor hearts based on patient acuity and waiting time contributes to the escalating costs of heart transplantation, ignores the potential outcome advantages of prospective tissue matching, and is vulnerable to manipulation. Costs have trebled in recent years, as recipients frequently spend weeks before transplantation as inpatients in intensive care units and become more susceptible to nosocomial complications. The findings from an international cooperative study suggest that patient survival is correlated with the level of histocompatibility (ie, human lymphocyte antigen [HLA]) matching. We observed a similar inverse association between retrospective fortuitous HLA matching and the risk of rejection in 39 patients undergoing heart transplantation over a 29-month period (p = 0.03 by nonparametric analysis). These observations prompted us to consider the feasibility of donor heart allocation based on the degree of HLA matching and waiting time alone. Current methods permit the accurate determination of HLA type in a matter of hours using donor peripheral blood alone. Human lymphocyte antigen typing, therefore, could be performed locally before organ harvesting, making issues of donor heart preservation irrelevant. We evaluated the extent of HLA matching that might be achieved practically. Forty-seven patients on our waiting list during calendar year 1991 were tested retrospectively for HLA matching with all geographically accessible 1991 heart donors identified by the United Network for Organ Sharing for all donors from hospitals east of the Mississippi River.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis of posttransplantation lymphoproliferative disorder by endomyocardial biopsy in a cardiac allograft recipient

Posttransplantation lymphoproliferative disorder is a serious complication of organ transplantation. This disorder has been linked to Epstein-Barr virus infections and can involve the transplanted organ. In the past the diagnosis of posttransplantation lymphoproliferative disorder in heart transplant recipients involving the transplanted organ was made primarily at autopsy. A case of a patient with posttransplantation lymphoproliferative disorder in whom the diagnosis was made initially by endomyocardial biopsy with confirmation by application of molecular techniques on mediastinal lymph node tissue and who was subsequently treated successfully is reported.

Effects of interleukin-3 after chemotherapy for advanced ovarian cancer

To define the maximum tolerated dose and to study whether recombinant human interleukin-3 (rhIL-3) reduced chemotherapy-induced neutropenia and thrombocytopenia, 20 chemotherapy-naive patients with advanced ovarian cancer eligible for treatment with 6 cycles of carboplatin-cyclophosphamide every 4 weeks (day 1) were entered in a phase I/II open, single-center trial. Cohorts of five patients received during 7 days 1, 5, 10, or 15 micrograms/kg/d rhIL-3 (days 5 through 11) in cycles 1, 3, and 5 by continuous intravenous (IV) infusion or once daily subcutaneous (SC) administration. In control cycles 2, 4, and 6, no rhIL-3 was administered. rhIL-3 significantly increased the recovery of leukocyte, neutrophil, and platelet counts, especially at 5, 10, and 15 micrograms/kg rhIL-3. rhIL-3 also increased basophil, eosinophil, monocyte, and lymphocyte counts at this dose steps. Effects on reticulocytes were limited. No difference in efficacy between SC and IV rhIL-3 treatment was found. Chemotherapy postponement for insufficient bone marrow recovery was necessary in 22 of 45 control cycles versus 2 of 49 rhIL-3 cycles (P less than .001). Platelet transfusions were required in 7 of 45 control cycles versus 3 of 50 rhIL-3 cycles (P less than .5). rhIL-3 up to 10 micrograms/kg/d could be administered without severe side effects. At 15 micrograms/kg/d, rhIL-3 headache was dose-limiting. Other side effects were fever, flu-like symptoms, nausea, skin rash, flushing, facial erythema, and urticaria. Liver toxicity occurred in rhIL-3 and control cycles. rhIL-3 slightly increased tumor necrosis factor alpha, C-reactive protein, and serum amyloid A plasma levels, whereas no effect on IL-6 plasma levels was observed. rhIL-3 administered SC appears to be an interesting hematopoietic growth factor for reduction of chemotherapy-induced myelotoxicity.

Value of peak exercise oxygen consumption for optimal timing of cardiac transplantation in ambulatory patients with heart failure

BACKGROUND

Optimal timing of cardiac transplantation in ambulatory patients with severe left ventricular dysfunction is often difficult. To determine whether measurement of peak oxygen consumption (VO2) during maximal exercise testing can be used to identify patients in whom transplantation can be safely deferred, we prospectively performed exercise testing on all ambulatory patients referred for transplant between October 1986 and December 1989.

METHODS AND RESULTS

Patients were assigned into one of three groups on the basis of exercise data: Group 1 (n = 35) comprised patients accepted for transplant (VO2 less than or equal to 14 ml/kg/min); group 2 (n = 52) comprised patients considered too well for transplant (VO2 greater than 14 ml/kg/min); and group 3 (n = 27) comprised patients with low VO2 rejected for transplant due to noncardiac problems. All three groups were comparable in New York Heart Association functional class, ejection fraction, and cardiac index (p = NS). Pulmonary capillary wedge pressure was significantly lower in group 2 than in either group 1 or 3 (p less than 0.05), although there was wide overlap. Patients with preserved exercise capacity (group 2) had cumulative 1- and 2-year survival rates of 94% and 84%, which are equal to survival levels after transplantation. In contrast, patients rejected for transplant (group 3) had survival rates of only 47% at 1 year and 32% at 2 years, whereas patients awaiting transplantation (group 1) had a survival rate of 70% at 1 year (both p less than 0.005 versus patients with VO2 greater than 14 ml/kg/min). All deaths in group 2 were sudden. By univariate and multivariate analyses, peak VO2 was the best predictor of survival, with only pulmonary capillary wedge pressure providing additional prognostic information.

CONCLUSIONS

These data suggest that cardiac transplantation can be safely deferred in ambulatory patients with severe left ventricular dysfunction and peak exercise VO2 of more than 14 ml/min/kg.

Recombinant tumour necrosis factor alpha administered subcutaneously or intramuscularly for treatment of advanced malignant disease: a phase I trial

The pharmacokinetics, toxicity and biological effects of subcutaneous and intramuscular treatment of cancer patients with recombinant tumour necrosis factor alpha (rTNF-alpha) was investigated. 17 patients suffering from refractory malignant disease were treated with either 1.0 micrograms/m2, 10 micrograms/m2 or 100 micrograms/m2 rTNF-alpha. Vital signs, peripheral blood cell counts, TNF and interferon (IFN) gamma serum levels, neopterin, beta 2-microglobulin, C reactive protein (CRP) and cortisol levels were measured immediately before and 2, 12, 24, 48 and 168 h after the first administration of rTNF-alpha. Tumour response was evaluated after 4 and 12 weeks of treatment. The pharmacokinetics followed the same characteristics as those reported for other cytokines. Major toxicities were dose dependent and comprised fever, constitutional symptoms and hypotension. TNF dependent changes were observed in serum levels of IFN-alpha, CRP, neopterin, beta 2-microglobulin, cortisol and white blood cell counts. No objective tumour response was observed. This study indicated that rTNF-alpha administered subcutaneously or intramuscularly results in measurable TNF serum levels, significant toxicity and biological response in absence of clinical efficacy in patients with advanced cancer.

[The intraperitoneal installation of gamma interferon for the treatment of refractory ovarian carcinoma]

Patients with refractory ovarian cancer were treated intra-peritoneally with interferon-gamma. The maximum tolerated dose was achieved at 2 mg/m2. The substance was administered 3 times per week every second week. Interferon-gamma treatment activated locally the macrophages and induced a rise in neopterin urine, serum, and ascites levels. The tumor marker CA-125 showed marked fluctuations of more than 100% during interferon treatment and this was not correlated with neopterin. A flu-like syndrome and especially fatigue were the dose limiting side effects. Two of 3 evaluable patients died on tumor progression whereas one is now 18 months clinically free of disease.

Epidemiologic study of physiological effects in usual and volunteer citrus workers from organophosphate pesticide residues at reentry

Biological parameters associated with organophosphate (OP) pesticide exposure were evaluated in a study of citrus harvesters. Changes in these parameters related to environmental residues of cholinesterase (ChE) inhibiting pesticides were studied. Further, it was determined whether usual and volunteer workers differed in their biochemical parameters after exposure to pesticide residues during field operations. Urine metabolite findings for usual farm workers showed that some exposure to OP pesticides had occurred. Too few workers were available during the reentry stage of the field study to evaluate the effect of this exposure on blood ChE. Baseline (nonexposure) acetylcholinesterase (AChE) and plasma cholinesterase (PChE) activities were significantly higher in usual (Mexican American) workers than in volunteer workers (student volunteers). Student volunteers in the test citrus grove showed statistically significant declines in PChE during the exposure period, yet changes in AChE activity, urine metabolites, and residue levels were very small. The implications of these findings are discussed in light of current reentry standards as well as future epidemiologic studies on reentry research.

Monitoring of grape harvesters for evidence of cholinesterase inhibition

This report describes the results of a long-term monitoring study of 36 grape harvesters who were occupationally exposed to organophosphate pesticide residues following reentry into vineyards during September and October 1976. The study was designed to evaluate biochemical parameters associated with organophosphate pesticide residues. Insignificant changes in blood cholinesterase activity were found. Some workers had very low levels of organophosphate metabolites in the urine during the entire 6 wk of study. Ethion dioxon was the only pesticide residue detected on the grape leaves. The harvesting of wine grapes involves numerous work crews of four to six people each, requiring a highly mobile monitoring staff. A single stationary location for collecting blood and urine samples will result in massive losses to follow-up since the workers cannot be relied on to report on their own. It is recommended that, to maximize worker cooperation, future monitoring studies rely more on analyses of urine specimens and less on venipuncture for evidence of pesticide exposure.

A controlled field trial of physiological responses to organophosphate residues in farm workers

Blood acetylcholinesterase (ACHE) and pseudocholinesterase (PCHE) activity and urinary dialkyl phosphate (DAP) excretion were measured in a group of 15 male agriculture field workers during a five-day thinning operation in a Northern California peach orchard. Eight men were randomly assigned to work in a Guthion-treated plot, and seven men to work in an adjoining plot free from organophosphate residues. Foliage samples were taken to measure dislodgeable and total Guthion residues. The daily mean percent change in the ACHE and in the PCHE activity was less than -10.0 percent of baseline values for each group of men. Mean ACHE activity of workers in the Guthion treated plot was different from that of workers in the control plot on the fifth exposure day. The mean PCHE activity of workers in the Guthion treated plot was not different from that of workers in the control plot. Daily group-mean urinary metabolite excretion levels for workers exposed to Guthion residues were highly correlated with their daily group-mean percent change in ACHE activity. No urinary metabolites were detected in workers in the control plot. Decay in Guthion residues was markedly slower in this trial than in a comparable study conducted one year previously, emphasizing the difficulty in setting re-entry intervals based on time elapsed from pesticide application. Suggestions were made to extend the time interval of future studies on the human health effects of organophosphate residue exposure, and to further refine urinary metabolite surveillance methods toward the goal of establishing a threshold level of metabolites which would correspond to meaningful exposure to these pesticides residues.

A comparative study on the influence of cysteamine and metyrapone on mixed-function oxygenase activities in variously pretreated liver microsomes from rats and mice

It has been found that metyrapone can inhibit both type I and type II mixed-function oxygenase reactions, while cysteamine inhibits only type I activity in this mammalian system. Following pretreatment with phenobarbital and 3-methylcholanthrene the half-maximal inhibiting concentrations for the O-demethylation of paranitranisol are increased for cysteamine and decreased for metyrapone. Both cysteamine and metyrapone give type II binding spectra with oxidized cytochrome P-450. The negative and positive peaks are at 393 and 426 nm respectively for metyrapone, and 410 and 434 nm for cysteamine. Cysteamine showed no binding comparable to that of metyrapone for reduced cytochrome P-450. Metyrapone showed little or no inhibition of the NADH cytochrome-c reductase (EC 1.6.1.1) or NADPH (EC 1.6.2.3) cytochrome-c reductase while cysteamine had a more or less strong inhibiting effect depending on the pretreatment of animals. Neither the binding to P-450 heme nor the inhibition of NADH and NADPH cytochrome-c reductase correlates well with cysteamine inhibition of total activity. It is therefore suggested that cysteamine reacts with an intermediate electron carrier of non-heme iron or glycoprotein character thus inhibiting mixed-function oxygenase activity.