Setting occupational exposure limits for pharmaceuticals

This work was undertaken to improve conditions for in vitro maturation and activation of porcine oocytes. Experiments were designed to compare: (i) electrical pulse frequency, (ii) methods of oocyte preparation, (iii) maturation conditions, and (iv) electrical poration medium on development. Oocytes were harvested by follicle dissection or aspiration, co-cultured with follicle shells in M199 based medium with or without media changes at 38.5 degrees C in 5% CO2 under non-static conditions for 48 h and electroactivated using single or multiple pulses (current strength 1.0 kV/cm for 50 microseconds in 0.28 M inositol or mannitol based media with 10 mM histidine) at different time intervals. The results showed: (i) neither the pulse frequency nor the pulse interval influenced rates of pronuclear formation but multiple pulse activation (3 pulses at 5 min intervals) induced a higher incidence of development and progression through the 4-cell block in contrast to one pulse activation; (ii) both the rate of nuclear maturation (88.6% vs. 77.6%) and post-activation cleavage (89.8% vs. 67.4%) were higher (P < 0.05) when oocytes were collected by follicle dissection rather than by aspiration; (iii) while changing to a hormone-free medium at 24 h was without effect on maturation (91.9% vs. 91.7%), rate of cleavage (81.6% vs. 72.3%, P < 0.05) at 24 h was enhanced by the medium change; and (iv) oocytes activated with 3 pulses 5 min apart in mannitol based medium at 48-49 h and at 53-54 h formed pronuclei at a comparable rate but subsequent parthenogenetic development was higher in the older eggs. By contrast, inositol-based medium supported development of young and old eggs equally well. Calcium and magnesium ions are, however, necessary in both mannitol and inositol media for activation of porcine oocytes matured in vitro. The present results suggest that optimal parthenogenetic activation and early development of IVM pig oocytes could be obtained if oocytes are harvested by dissection, cultured for 24 h in hormone-containing medium before being placed in hormone free medium and activated at 48 h in inositol based medium using a three pulse activation system.     

Examples of MAK values and carcinogenicity classification for mixtures

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) generally sets MAK values for single pure substances. MAK values for mixtures are only established after specific toxicological evaluation of the particular mixture. In practice, there are a few cases in which a common MAK value for the sum of all components was set, such as for mixtures of isomers (e.g. xylenes) or mixtures of related compounds (e.g. Kathon), in which the components of the mixture show comparable toxicological effects. For mixtures of isomers with different toxicological potentials, different MAK values for the single isomers are usually established. The only exception is for the isomer mixture of alpha- and beta-hexachlorocyclohexane, for which a mathematically calculated MAK value was proposed. A safe threshold cannot be established for mixtures containing substances with a genotoxic and carcinogenic potential. These mixtures are categorized either according to the proven carcinogenicity of the mixture, such as alpha-chlorinated toluenes, or according to the carcinogenic substances included, as for pyrolysis products such as coal tars.     

Secondary pharmaceuticals manufacturing

Drs. Burling and Shah examine the second part of the pharmaceuticals manufacturing process, in which formulations for drug delivery are determined. Several types of formulations and their potentials for occupational exposure are reviewed.     

The carcinogenicity of metals in humans

Epidemiologic evidence on the relation between exposure to metals and cancer is reviewed. Human exposure to metals is common, with wide use in industry and long-term environmental persistence. Historically, the heaviest metal exposures occurred in the workplace or in environmental settings in close proximity to industrial sources. Among the general population, exposure to a number of metals is widespread but generally at substantially lower levels than have been found in industry. The carcinogenicity of arsenic, chromium, and nickel has been established. Occupational and environmental arsenic exposure is linked to increased lung cancer risk in humans, although experimental studies remain inconclusive. Experimental studies clearly demonstrate the malignant potential of hexavalent(VI) chromium compounds, with solubility being an important determining factor. Epidemiologic studies of workers in chromium chemical production and use link exposure to lung and nasal cancer. Experimental and epidemiologic data show that sparingly-soluble nickel compounds and possibly also the soluble compounds are carcinogens linked to lung and nasal cancer in humans. Some experimental and epidemiologic studies suggest that lead may be a human carcinogen, but the evidence is inconclusive. Although epidemiologic data are less extensive for beryllium and cadmium, the findings in humans of excess cancer risk are supported by the clear demonstration of carcinogenicity in experimental studies. Other metals, including antimony and cobalt, may be human carcinogens, but the experimental and epidemiologic data are limited.     

The carcinogenicity of environmental tobacco smoke

Male strain A/J mice were exposed for 6 h a day, 5 days a week to environmental tobacco smoke (ETS) generated from Kentucky 1R4F reference cigarettes. Chamber concentrations were 87 mg/m3 of total suspended particulate matter (TSP), 246 p.p.m. of CO and 16 mg/m3 of nicotine. After 5 months, 33% of the ETS exposed and 11% of the control animals had one or several lung tumors; the difference was statistically not significant. A second group of animals exposed for 5 months to ETS was allowed to recover for another 4 months in filtered air. When they were killed, 85% of the ETS animals had lung tumors (average number per lung: 1.4 +/- 0.2), whereas in the control group 38% had lung tumors (average number of lung tumors in all animals 0.5 +/- 0.2). The differences in tumor incidence and multiplicity were statistically significant. More than 80% of all tumors were adenomas, the rest adenocarcinomas. When animals were pretreated with a carcinogen, lung tumor multiplicity was lower in the ETS exposed animals after 5 months compared with controls injected with a carcinogen and kept in air. However, after an additional 4 month recovery period in air, lung tumor multiplicities were the same in ETS plus carcinogen exposed mice as in carcinogen-treated air-exposed controls. Histopathologic and morphometric analysis of the lung tissue failed to reveal any differences between ETS exposed and control animals. However, immediately after ETS exposure, immunohistochemistry revealed increased staining for CYP1A1 in airway epithelia and lung parenchyma; following recovery in air, the staining disappeared again. Analysis of cell kinetics showed an initial burst of increased DNA synthesis in the epithelial cells of the airways and a smaller early positive response in the parenchyma. Feeding of butylated hydroxytoluene during ETS exposure did not modulate lung tumor development. It was concluded that ETS is a pulmonary carcinogen in strain A/J mice.     

New pharmaceuticals from marine organisms

Definitions of 'marine biotechnology' often refer to the vast potential of the oceans to lead to new cures for human and animal disease; the exploitation of natural drugs has always been the most basic form of biotechnology. Although only initiated in the late 1970s, natural drug discovery from the world's oceans has been accelerated by the chemical uniqueness of marine organisms and by the need to develop drugs for contemporary, difficult to cure, diseases. Current research activities, while primarily within the academic laboratories, have generated convincing evidence that marine drug discovery has an exceedingly bright future.     

Prevention of carcinogenicity of anticancer drugs by metallothionein induction

We examined the efficacy of metallothionein induction in the prevention of the carcinogenic action of cis-platinum and melphalan administered repeatedly to mice over a relatively long period. The increased pulmonary metallothionein induced by bismuth or zinc compounds during the period of chemotherapy with cis-platinum or melphalan protected the mice from carcinogenesis of these drugs in the lung. These results suggested the efficacy of metallothionein inducers in suppression of carcinogenicity considered as a secondary effect of anticancer agents in cancer chemotherapy.     

Extraction of pharmaceuticals using pressurised carbon dioxide

This paper reviews the applications of super- and sub-critical carbon dioxide for the extraction of pharmaceuticals from various matrices. The matrices covered are divided into the following types: animal feed, formulations, biological and miscellaneous, with various sub-divisions as appropriate. The polar nature of most pharmaceuticals often precludes the use of carbon dioxide only, so it is common to find the addition of a more polar solvent, as modifier. As the majority of sample types covered are solid, little if any pre-treatment is required, with the exception of grinding, prior to insertion in the sample extraction cell. For liquid-type matrices, sample pre-treatment is the normal. Often this may involve adsorption on an inert support e.g. Celite or diatomaceous earth, or immobilisation on a functionalised silica surface, e.g. C18. The later may take the form of a solid phase extraction cartridge or disk. An attempt has also been made to sample from liquid matrices directly using a modified extraction cell. The variety of sample types, matrices and analyte polarity places stringent requirements on the use of pressurised carbon dioxide. Its potential for effective recovery is examined in this review.     

HPLC-fluorescence determination of unconjugated estrogens in pharmaceuticals

The demonstration of synergistic interaction between differentiation inducing agents and DNA synthesis inhibitors suggests that these two groups act by two different mechanisms. We prospectively studied the response rate, response duration, survival, and toxicity in 10 patients with myelodysplastic syndrome (MDS) treated with all trans retinoic acid (ATRA) and low dose cytosine arabinoside (ara-C). These patients diagnosed between October 1993 and May 1995 were treated with ATRA (45 mg/M2/day) for 90 days followed by 90 mg/M2 on alternate day till Day 275; together with Ara-C (10 mg/m2) subcutaneously twice daily for 21 days for a total of 6 cycles. These patients were analyzed for response after 3 cycles of LD Ara-C and at the time of completion of therapy. Toxicity was recorded at the end of each cycle of Ara-C. There were 6 male and 4 female patients in the age range of 24 to 76 years. The morphological diagnosis was chronic myelomonocytic leukemia in 2, refractory anemia with excess blasts in 4 and refractory anemia with excess blasts in transformation in 4. Only 1 patient achieved a complete remission and 1 patient achieved a partial response. Four patients had progressive disease on treatment. One patient died of neutropenic sepsis and 1 of resistant thrombocytopenia and intracranial hemorrhage while on treatment. One patient refused further treatment after a minor clinical response and in 1 patient treatment was stopped due to toxicity. This data in a pilot study with a limited number of patient suggests that ATRA in combination with Ara-C has little effect in MDS.     

Structure-based methods for predicting mutagenicity and carcinogenicity: are we there yet?

There is a great deal of current interest in the use of commercial, automated programs for the prediction of mutagenicity and carcinogenicity based on chemical structure. However, the goal of accurate and reliable toxicity prediction for any chemical, based solely on structural information remains elusive. The toxicity prediction challenge is global in its objective, but limited in its solution, to within local domains of chemicals acting according to similar mechanisms of action in the biological system; to predict, we must be able to generalize based on chemical structure, but the biology fundamentally limits our ability to do so. Available commercial systems for mutagenicity and/or carcinogenicity prediction differ in their specifics, yet most fall in two major categories: (1) automated approaches that rely on the use of statistics for extracting correlations between structure and activity; and (2) knowledge-based expert systems that rely on a set of programmed rules distilled from available knowledge and human expert judgement. These two categories of approaches differ in the ways that they represent, process, and generalize chemical-biological activity information. An application of four commercial systems (TOPKAT, CASE/MULTI-CASE, DEREK, and OncoLogic) to mutagenicity and carcinogenicity prediction for a particular class of chemicals-the haloacetic acids (HAs)-is presented to highlight these differences. Some discussion is devoted to the issue of gauging the relative performance of commercial prediction systems, as well as to the role of prospective prediction exercises in this effort. And finally, an alternative approach that stops short of delivering a prediction to a user, involving structure-searching and data base exploration, is briefly considered.     

Need for dietary control by caloric restriction in rodent toxicology and carcinogenicity studies

The conditions under which laboratory animals are maintained can powerfully influence the results of toxicological studies utilized for risk assessment. Nutrition is of importance in toxicological bioassays and research, because diet composition and the conditions under which it is fed can affect the metabolism and activity of xenobiotic test substances and alter the results and reproducibility of long-term studies. It is known that ad libitum (AL) overfed sedentary laboratory rodents suffer from an early onset of degenerative disease and diet-related tumors that lead to poor survival in chronic bioassays. AL-fed animals are not well-controlled subjects for any experimental studies. Examination of study-to-study variability in food consumption, body weight, and survival in carcinogenicity studies for the same strain or stock of rodents shows tremendous laboratory-to-laboratory variability. However, a significant correlation between average food (calorie) consumption, adult body weight, and survival has been clearly established. The use of moderate dietary restriction (DR) results in a better controlled rodent model with a lower incidence or delayed onset of spontaneous diseases and tumors. Operationally simple, moderate DR significantly improves survival, controls adult body weight and obesity, reduces age-related renal, endocrine, and cardiac diseases, increases exposure time, and increases the statistical sensitivity of these expensive, chronic bioassays to detect a true treatment effect. A moderate DR regimen of 70-75% of the maximum unrestricted AL food intake is recommended as a nutritionally intelligent, well-established method in conducting well-controlled toxicology and carcinogenicity studies.     

Industry's efforts: devices and pharmaceuticals

The pharmaceutical industry has been irreversibly affected by the changes occurring in healthcare. Despite the obvious contributions of pharmaceuticals to human health, our customers are demanding that we help the patient and contribute to value, whether it be in terms of cost, clinical outcomes, or quality of life. We are learning to balance the variables to ensure that cost plus quality equals value in the marketplace in three ways: by focusing on the needs of the customers and demonstrating value through outcomes research, by maintaining an emphasis on innovation, and by taking an active role in the public arena to direct the course of our future. Outcomes research proves the value of what we do. Economic data will have to be correlated with clinical data. In addition to standard clinical and economic parameters, we must also provide quality of life data. Collaboration between the academic and the practicing community produces a win-win situation for both parties. Industry and practitioners are bonded together ineluctably in the service of the patient. Working together we can shape our future and the future of our patients.     

Ethylene thiourea-a study of possible teratogenicity and thyroid carcinogenicity

Clinical and genetic investigations were performed on seven members of a family suffering from multiple hereditary fibromatosis. These studies indicate that the responsible gene appears to be coupled and transmitted with that of the rhesus system, located at chromosome one. The diagnosis, differential diagnosis and therapy, as well as histological alterations are pointed out and the importance of hormonal factors is discussed.