Safety evaluation of genetically modified foods.

The concept of substantial equivalence has been accepted as the cornerstone of the health hazard assessment of genetically modified (GM) foods (OECD 1993). Substantial equivalence is the most practical approach to address the safety of foods or food components derived from GM crops and is based on comparison of the phenotypic and compositional characteristics of the parent crop and the GM crop. Basically, three categories of GM crops can be considered (FAO/WHO 1996; EU 1997): (a) GM crops which have the same composition as the parent crop, (b) GM crops which have the same composition as the parent crop with the exception of a well-defined trait, and (c) GM crops which are different from the parent crop. For the safety assessment of the first category of GM foods only a molecular characterisation of the genetic insert is sufficient, whereas for the second category a safety assessment of the expressed protein(s) is also required. For the last category an extensive evaluation including bioavailability and wholesomeness studies are required, beside the molecular characterisation and safety assessment of the expressed protein(s) and their products. By molecular characterisation is meant the position, nature, stability and number of copies of the inserted DNA. Substantial equivalence is established by the determination of the phenotypic characteristics (e.g. resistance against diseases, agronomic properties) and the complete chemical composition of the plant including nutrients, toxicants, antinutrients, and allergens. The toxicity of the expressed protein(s) is assessed by their homology with known protein toxins, degradation in the gastro-intestinal tract, stability to food processing and acute toxicity in rodents. The possible allergenicity of the expressed proteins is evaluated by comparison of their amino acid sequence with that of known allergens and determination of their stability to digestion and food processing. If the source of the genetic insert is allergenic then the use of solid-state immunoassays, skin prick tests and even food challenge tests can be considered.

Human ocular effects from self-reported exposures to Roundup herbicides.

We evaluated ocular effects from reported human exposures to Roundup herbicides based on 1513 calls to an American Association of Poison Control Centers (AAPCC) certified regional poison center during the years 1993 through 1997. The preponderance of reported exposures were judged by poison center specialists to result in either no injury (21%) or transient minor symptoms (70%). There was some temporary injury in 2% of cases; one injury took more than 2 weeks to resolve. In no instance did exposure result in permanent change to the structure or function of the eye. Since the representativeness of calls to poison control centers is unknown, several interpretations of these findings are possible. The most conservative interpretation is that there were no serious ocular effects from exposure to Roundup herbicides during a 5 year period among callers to a single regional poison center. A less conservative interpretation would be that severe ocular effects from Roundup exposures are rare among users of these products.

An evaluation of the carcinogenic potential of the herbicide alachlor to man.

Chronic bioassays have revealed that alachlor caused nasal, thyroid, and stomach tumours in rats but was not carcinogenic in mice. Significant increases in thyroid and stomach tumours were observed only at doses that exceeded the maximum tolerated dose (MTD). While nasal tumours were found at doses below the MTD, they were small and benign in nature. This publication describes the work undertaken by Monsanto to understand the carcinogenic mode of action of alachlor in the rat and to investigate the relevance to humans. The genetic toxicity of alachlor has been investigated in an extensive battery of in vitro and in vivo test systems. In addition, target-specific mutagenicity tests, such as the COMET assay and DNA binding in nasal tissue, were carried out to investigate any possible in-situ genotoxic action. The weight-of-evidence analysis of all available data clearly demonstrates that alachlor exerts its carcinogenicity in the rat by non-genotoxic mechanisms. In the rat, alachlor is initially metabolised primarily in the liver through the P-450 pathway and by glutathione conjugation. The glutathione conjugates and their metabolites undergo enterohepatic circulation with further metabolism in the gastrointestinal tract, liver, and then nasal tissue where they can be converted to a diethyliminoquinone metabolite (DEIQ). This electrophilic species binds to the cysteine moiety of proteins leading to cell damage and increased cell turnover. When comparisons of in vitro nasal metabolic capability were made, the rat's capacity to form DEIQ from precursor metabolites was 38 times greater than for the mouse, 30-fold higher than monkey, and 751 times greater than that of humans. This data is consistent with the results of studies showing in vivo formation of DEIQ-protein adducts in the nasal tissue of rats but not mice or monkeys. The lack of DEIQ nasal adducts in mice is consistent with the lack of nasal tumours in that species. When the differences between rat and humans in the capacity for initial glutathione conjugation by the liver and nasal tissue are also taken into account, the rat is found to be even more susceptible to DEIQ formation than man. Based on this, it is clear that the potential for DEIQ formation and nasal tumour development in humans is negligible. The mechanism of stomach tumour formation has been studied in the rat. The results demonstrated that the mechanism is threshold-sensitive and involves a combination of regenerative cell proliferation and a gastrin-induced tropic effect on enterochromaffin-like (ECL) cells and stem cells of the mucosal epithelium. The absence of a carcinogenic effect in mice and of any preneoplastic effect in monkeys treated with very high doses is indicative ofthe species-specific aspect of this mechanism of action. The results of studies on thyroid tumour production indicate that alachlor is acting indirectly through the pituitary-thyroid axis by increasing the excretion of T4 by enhanced glucuronidation and subsequent biliary excretion. The increased excretion reduces plasma T4 levels and a feedback mechanism leads to increased synthesis of TSH by the pituitary. Chronic stimulation of the follicular epithelium of the thyroid by TSH produces hyperplasia and ultimately tumour formation. This non-genotoxic, threshold-based mechanism is well established and widely considered to be not relevant to humans. In this work, the modes of action for the three types of tumours elicited in the rat by alachlor were investigated. All are based on non-genotoxic, threshold-sensitive processes. From all the data presented it can be concluded that the tumours detected in the rat are not relevant to man and that alachlor presents no significant cancer risk to humans. This conclusion is supported by the lack of mortality and tumours in an epidemiology study of alachlor manufacturing workers.

Mixture risk assessment: a case study of Monsanto experiences.

Monsanto employs several pragmatic approaches for evaluating the toxicity of mixtures. These approaches are similar to those recommended by many national and international agencies. When conducting hazard and risk assessments, priority is always given to using data collected directly on the mixture of concern. To provide an example of the first tier of evaluation, actual data on acute respiratory irritation studies on mixtures were evaluated to determine whether the principle of additivity was applicable to the mixture evaluated. If actual data on the mixture are unavailable, extrapolation across similar mixtures is considered. Because many formulations are quite similar in composition, the toxicity data from one mixture can be extended to a closely related mixture in a scientifically justifiable manner. An example of a family of products where such extrapolations have been made is presented to exemplify this second approach. Lastly, if data on similar mixtures are unavailable, data on component fractions are used to predict the toxicity of the mixture. In this third approach, process knowledge and scientific judgement are used to determine how the known toxicological properties of the individual fractions affect toxicity of the mixture. Three examples of plant effluents where toxicological data on fractions were used to predict the toxicity of the mixture are discussed. The results of the analysis are used to discuss the predictive value of each of the above mentioned toxicological approaches for evaluating chemical mixtures.

Acute and recurrent effort-related compartment syndrome in sports.

An effort-related compartmental syndrome is a condition in which increased pressure in a muscle compartment impedes blood flow and compromises metabolic demands of the tissues within that space. One can clinically distinguish acute irreversible and chronic reversible types. The aetiology relates in most instances to a limiting noncompliant fascia surrounding the affected muscle compartment. Sports activity leads to increased muscle volume and if there is a noncompliant fascia this will result in an excessive intracompartmental pressure which interferes with muscle blood flow. As a consequence of a reduced intracompartmental blood flow a reversible (recurrent) or irreversible (acute) exercise ischaemia, a so-called 'compartmental syndrome' occurs. A compartment syndrome is typically encountered in the lower leg, but it can be also observed in the upper leg and even in the forearm. Clinical history plays a key role in the diagnosis. Pain, muscle tightness and cramp-like feeling are the most common complaints. Weakness, paralysis and numbness are seen, especially in the acute syndrome. Symptoms appear at a certain intensity of activity and disappear at rest in the chronic compartment syndrome, but in the acute type pain will persist and will be severe. It is clearly an effort-related pain syndrome. Physical examination is not always useful in diagnosing a recurrent syndrome, but in the acute syndrome one will find high sensitivity to pressure and tenseness over the involved muscle compartment. Decreased or loss of active motion and sensation in the involved compartment are frequently seen. Tissue pressure monitoring can confirm the diagnosis for both types.(ABSTRACT TRUNCATED AT 250 WORDS)

An objective method for the evaluation of eye irritation in vivo.

It is generally agreed that intra- and interlaboratory variations in the evaluation of eye irritants are mainly due to the subjective judgement of eye lesions. The scoring of the palpebral conjunctivae is a typical example. To eliminate these difficulties in assessing eye irritants the relationship between corneal swelling, which can be determined using an objective technique, and the reading of other symptoms was investigated. The in vivo eye irritation assay was carried out on 34 substances according to the protocol laid down in Annex V, part B of Directive 79/831/EEC of the European Community on the classification, labelling and packaging of dangerous substances. Results were obtained for erythema, oedema, corneal opacity and corneal swelling. Erythema, oedema and opacity were evaluated according to the interpretation rules laid down in Annex VI, part IID of the EEC Directive 83/467/EEC. Corneal swelling was determined by the ultrasonic pachometer technique. Good correlations were found between the mean percentage corneal swelling after 24, 48 and 72 hr and the mean corneal opacity (r = 0.94) and erythema scores (r = 0.93) after the same observation times. The corneal swelling scores measured after 24 hr using the ultrasonic pachometer are comparable with those reported in the literature, which were obtained by optical pachometry. The good correlation with the other effects scored and the good repeatability of the results opens the possibility of introducing an objective and sensitive method into the ocular irritation assay and so reducing intra- and interlaboratory variations.

The enucleated eye test: A comparison of the use of ultrasonic and optic pachometers.

The ultrasonic pachometer has been introduced recently into our laboratory for use in the eye-irritation test using enucleated rabbit eyes. We have compared the performance of this kind of pachometer with that of the optical pachometer. The results for corneal swelling, reported by Burton et al. (1981) and obtained using an optic pachometer, were compared with those obtained using an ultrasonic pachometer to test the same 11 substances. The mean corneal swelling 240 min after application of the test substances to four eyes resulted in a very good correlation (r = 0.984) between the optic and ultrasonic pachometer data. A good Spearman rank correlation (r = 0.906; P < 0.0005) was also found between corneal swelling and opacity. The use of the ultrasonic pachometer requires the contact of the ultrasonic probe tip with the corneal epithelium. Although epithelial damage was observed due to probe contact, we were not able to demonstrate that this would influence corneal swelling. The ultrasonic technique is a considerable improvement over the optic technique because:

Adductor tendinitis and musculus rectus abdominis tendopathy.

Groin injuries are becoming more common today in soccer. Conservative treatment consisting of rest, physiotherapy, and medication yields favorable results in only 38% of the long-standing lesions. Operative treatment is indicated in selected cases. Better knowledge of the underlying pathology and a more accurate initial conservative treatment directed to the ethiopathogenesis could solve many of the problems. However, in our experience a simple subcutaneous adductor tenotomy and/or a rectus abdominis tenotomy in combination with a fasciaplasty was done successfully in 75 of 81 patients. There was no loss of power in this group of patients as measured and compared with a control group.

Recurrent dislocation of the peroneal tendons. Results of rerouting the tendons under the calcaneofibular ligament.

Nine patients (11 cases) with recurrent dislocation of the peroneal tendons who were treated by surgically rerouting the tendons under the calcaneofibular ligament were reviewed. Mean follow-up time was 30.5 months. An excellent or good result was obtained in all cases. This operative technique was previously described in 1975, by Sarmiento and Wolf, in a case report.

Partial arthroscopic meniscectomy versus total open meniscectomy.

One hundred sixteen patients who had undergone partial arthroscopic meniscectomy were reviewed in a short-term follow-up study (mean follow-up: 16 months). Their results were compared with those of a group of 402 patients who had been treated previously by conventional open meniscectomy in the same hospital. Average age in the arthroscopic group was 40 years, in the open group 34. Average sick leave was 4 weeks in the arthroscopic group, 10 weeks in the arthrotomy group. In the endoscopic group, there was virtually no sick leave for self-employed people, but 7 weeks if the lesion was sustained at work. Top-class sportsmen resumed competition 5 weeks after arthroscopy, 8 weeks after conventional meniscectomy. Still, most of them complained of prolonged synovial reaction resulting in a period of poor physical condition and performance. Of the patients treated by arthroscopy, 7.5% presented minor problems related to the approach (anteromedial-transpatellar), while 21.5% had similar problems after routine anteromedial incision in the open meniscectomy group. The overall results after arthroscopy were excellent in 49 cases (41.5%), good in 51 (43%), fair in 14 (12%), and poor in four (3.5%). These short-term results are comparable to those of the open meniscectomy group. The short-term results in the older patients confirm our belief that (partial) meniscectomy is useful for the older patient with a history of mechanical meniscal problems, with or without cartilage degeneration, provided one is not dealing with frank osteoarthrosis and secondary varus or valgus deformity.(ABSTRACT TRUNCATED AT 250 WORDS)

Secondary reconstruction of the lateral ligaments of the ankle by the Chrisman-Snook technique.

Nineteen patients suffering from chronic post-traumatic instability at the ankle were treated surgically by the Chrisman-Snook technique. Mean follow-up time was 38 months. Each patient reported an initial major inversion trauma, followed by repetitive sprains resulting in apprehension, giving way, pain, and swelling at the ankle. Before surgery all patients engaged in sports were obliged to modify or even stop their activities for reasons related to their ankle problem. After reconstruction instability was abolished in all cases and an excellent or good result was obtained in 18. The three top sportsmen included in our series were all able to return to their pre-injury level of sport without any restrictions. A careful dissection of the branches of the sural nerve is considered to be essential, since postoperative paresthesia or numbness over the sural nerve region was found in six cases. This study confirms the efficacy of the Chrisman-Snook technique in the treatment of ankle instability, even in cases of gross ankle laxity or with patients engaged in very demanding sports.

Impact of dilution on the pharmacokinetic behavior of acetaminophen in rabbits after oral administration.

Seven rabbits received two different acetaminophen solutions by gavage in a randomized crossover fashion. In one administration the dose was given in a concentrated small volume of an ethanol-glycerol-water mixture (preparation I). In another administration an identical dose was given in a 10-fold water-diluted volume of the same mixture (preparation II). Three rabbits also received the same dose in a 10-fold original mixture volume (preparation III). The acetaminophen concentrations were measured by HPLC in plasma samples collected for 3.5 h after gavage. The lag times ranged from 2.5 to 23 min for preparation I and from 2.2 to 29 min for preparation II. The mean peak plasma concentrations (12.38 micrograms/mL for preparation I and 9.14 micrograms/mL for preparation II) and the mean time-to-peak concentrations (26.57 min for preparation I and 36.57 min for preparation II) were significantly different. The total area under the plasma concentration curve and the absorption and elimination half-lives did not, however, differ significantly. For the three rabbits receiving the acetaminophen doses in the 10-fold ethanol-glycerol-water mixture volumes (preparation III), the total area under the plasma concentration curve obviously was increased.

Chronic leg pain in athletes due to a recurrent compartment syndrome.

A series of 29 patients, all engaged in sports activity on a regular basis, suffering from recurrent compartmental syndrome, is reported. The syndrome is not restricted only to long distance runners but to athletes involved in a variety of sports activities (soccer, volleyball, cycle racing, gymnastics, judo, physical education, and long distance running). Although most patients presented activity-related leg pain, some patients mainly complained of ankle weakness and recurrent ankle distortions at fatigue. The wick catheter technique proved to be most useful to determine which compartments were involved. The severity of clinical symptoms correlated highly with the anomalies of the tissue pressure measurements. The predominance of deep posterior compartment and multiple compartment involvement are in contrast with most previous reports. Conservative treatment was unsuccessful in every patient, whereas surgical decompression of the involved compartments yielded favorable results in those cases where all the involved compartments were released.

Anterior subluxation of the lateral tibial plateau. A new clinical test and the morbidity of this type of knee instability.

A new clinical test is presented for the diagnosis of anterolateral knee instability. The advantages of the test are obviation of apprehension- and muscle spasm avoiding false negative results and also the recognition by the patient of his sensation of "collapsing at the knee". This allows for differentiation between "giving away" due to a torn meniscus alone and concomitant anterolateral knee instability. It implies important consequences for prognosis and treatment of the knee problem of the athlete. Underlying pathology consists of a torn anterior cruciate ligament and primary or secondary stretching of the soft tissues at the lateral and posterolateral capsule. These lesions and a positive test for anterolateral knee instability does not inevitably result in a disability for sports activity. The dynamic muscular control protects the knee in many instances from collapsing at cross over cutting.

Extraction and GLC analysis of pyrithyldione in highly putrified human postmortem samples.

Pyrithyldione was isolated from highly putrified human brain and small intestine samples by ether extraction followed by alumina column cleanup. The total yield was 90+/- 5%. No derivatization was necessary prior to GLC analysis.