Laboratory evaluation metabolic laboratories

Finally, a laboratory evaluation completes the initial evaluation. This includes a battery of blood tests to rule out infection, metabolic abnormality, or hormonal disturbance. It must also include a drug screen. Unfortunately, most drug screens do not detect the designer drugs like Ecstasy that are an ever-increasing cause of acute psychosis. The initial evaluation should always include a CT or MRI brain scan, preferably the latter. 

Species variations that may seriously affect the validity of laboratory animal metabolism studies as predictive models for man are a problem without apparent solution. For proper evaluation of the toxicological significance of pesticides to man, metabolism... 

The clinical presentations of inherited metabolic diseases are often nonspecific, and various laboratory tests provide the information necessary to establish a diagnosis. Often multiple routine and metabolic laboratory studies are needed, and these laboratory studies are complanentary. The astute clinician can use the combination of these laboratory studies to initiate emergency treatment in an acute setting, to make a probable diagnosis, and to evaluate the long-term treatment of patients with an inborn error of metabolism. 

Although many of the simple urine tests listed below are no longer being done in large metabolic centers, they are still of importance for small laboratories and in countries where new more sophisticated techniques are not available. Some are nonspecific, but a positive test may direct one to a more specific test indicating the need for further evaluations. To look at a urine sample and smell it should be a routine for a good metabolic laboratory. 

This is important not only in field investigations. Even in laboratory experiments on the metabolism of xenobiotics, problems of association between the substrate and the microbial cells may occur. If this were not quantitatively evaluated or eliminated, the results and interpretation of such experiments would be seriously compromised. 

The activities of enforcement laboratories should not be focused on irrelevant problems. Therefore, a clear definition of the relevant residue is needed. In the crops and food sector, procedures are well established to derive the two residue definitions, one for risk assessment and one for monitoring, from metabolism studies. As far as environmental samples are concerned, there is much potential for improvement. There are no clear criteria as to which metabolites should be included in monitoring and control programs. Additionally, the development of criteria for nonpriority pesticides, e.g., naturally occurring compounds or low-risk products, which can be excluded from monitoring exercises would be helpful for laboratories and evaluators. 

Bioremediation also has its limitations. Some chemicals are not amenable to biodegradation, for instance, heavy metals, radionuclides, and some chlorinated compounds. In some cases, the microbial metabolism of the contaminants may produce toxic metabolites. Bioremediation is a scientifically intensive procedure that must be tailored to site-specific conditions, and usually requires treatability studies to be conducted on a small scale before the actual cleanup of a site.13 The treatability procedure is important, as it establishes the extent of degradation and evaluates the potential use of a selected microorganism for bioremediation. A precise estimate on vessel size or area involved, speed of reaction, and economics can therefore be determined at the laboratory stage. 

Richard C. Honeycutt, Ph.D., was born in Newport News, VA, in 1945. He attended Anderson University in Anderson, IN, from 1963 to 1967 and earned an A.B. in Chemistry. He received his Ph.D. in Biochemistry from Purdue University in 1971 and served as a Postdoctoral Fellow from 1971 to 1973 at the Smithsonian Institution s Radiation Biology Laboratory. Dr. Honeycutt worked as a Senior Chemist at Rohm and Haas Company from 1973 to 1976 and as a Senior Metabolism Chemist at Ciba Geigy from 1976 to 1989. Currently, he is President of the Hazard Evaluation and Regulatory Affairs Company, Inc., which he founded in 1990, and is an analytical biochemist and field research specialist/consultant engaged in exposure assessment of pesticides to humans and the environment. 

Delirium. Delirium is an abrupt change in mental status often accompanied by agitation and seemingly psychotic symptoms that may resemble mania. Unlike mania, however, delirium is commonly characterized by a fluctuating level of consciousness and disorientation. The chief precipitants of delirium include infections, medications, and metabolic disturbances. Therefore, all patients who present in an acutely agitated state should undergo a comprehensive yet expeditious medical evaluation to rule out potential causes of delirium. This evaluation must include a thorough physical examination and a battery of laboratory tests. 

Much research has been invested to identify a common and validated test method that may be used in all industrial laboratories concerned by phototoxicology. Cultured mammalian cells constitute an essential model for the evaluation of phototoxicity. Such systems include all biological targets (lipids in membranes, proteins, nucleic acids) as well as active pathways likely to modulate the phototoxic impact (apoptotic pathways, cellular defenses, endogenous antioxidants, repair pathways, metabolism). 

Dreibelbis, W.G, Ealy, J.A. Porter, W.E. (1982) Industrial hygiene monitoring for evaluation of employee exposure and control measures in coal conversion program at Oak Ridge National Laboratory. In Cooke, M. Dennis, A.J., eds, Polycyclic Aromatic Hydrocarbons Mechanisms, Methods and Metabolism, Proceedings of the Eight International Symposium, Columbus, OH, Battelle Press, pp. 351-361... 

Laboratory rodents are the animal models most commonly used to identify hazards in reproductive toxicity. Rodents are used because they are small animals, the assay cost is moderate and there is a large database of toxicology information on these species (e.g., dose-response, metabolism, kinetics, etc.). The rat has proven to be a good model for human reproductive hazard evaluation (Francis et al., 1990). 

The Berry spot test provides a rapid qualitative evaluation of urine. GAGs react with toluidine blue, a cationic dye, to yield a pink-colored compound. Alternative spot tests have been published but suffer from the same drawbacks regarding false-negative and false-positive specimens [2, 10, 15, 34]. Nevertheless, this fast procedure may pick up patients who have been referred to a laboratory for other metabolic examinations. For specific, initial MPS testing, the 1,9-dimethylene blue (DMB) assay, described below, is recommended. 

In recent years, biochemical genetics has witnessed enhanced exposure as a laboratory discipline because of the advent of expanded newborn screening around the world. Sample numbers in most biochemical genetics laboratories are growing because of the required evaluation of positive newborn screening results. Accordingly, it is in everyone s interest (physician, patient, metabolic specialist, and other healthcare providers) that biochemical genetics laboratories have the most up-to-date methods available on their test menu. 

---