Evaluation of the genotoxic activity of dicamba and atrazine herbicides in several Mexican and South American varieties of sweetcorn (Zea mays L.)

Corn is a major crop and various herbicides are used to maximize its production, which include a dicamba-atrazine mixture. This has great advantages, but can also induce DNA damage. Genotoxic activity was assessed by comet assay following application of two concentrations of dicamba-atrazine: 1000-2000 and 2000-4000 ppm. Apical meristem leaf nuclei from 119 varieties of sweetcorn plants from Mexico and South America, and from five commercial sweetcorn hybrids were used. Each accession comprised two individuals per concentration and two controls. Significant genotoxic activity (P < 0.001) was observed following treatment with 1000-2000 and 2000-4000 ppm compared to the negative control. There was no difference in the genotoxic activity induced by both 1000-2000 and 2000-4000 ppm concentrations in plants from Mexico and South America (P > 0.05) except (P < 0.05) in the 2000-4000 ppm treated plants from Mexico and the 1000-2000 ppm treated plants from South America. Sweetcorn hybrids showed significant genetic damage (P < 0.01) at all concentrations compared to the negative controls. Thus, the dicamba-atrazine mixture caused genetic damage to corn plants, and it suggested that Mexican sweetcorn is more sensitive to dicamba-atrazine than the maize varieties from South America. Neither hybrid status nor the origin avoids DNA damage caused by Marvel. Thus, maize can be useful as a biomonitor of genetic damage induced by chemicals and to identify possible phenotypes based upon the amount of genetic damage induced by herbicides and selection of resistant genotypes.

Assessing the genotoxicities of sparteine and compounds isolated from Lupinus mexicanus and L. montanus seeds by using comet assay

The genus Lupinus is widely distributed. Its seeds are used for animal and human food, and Lupinus possesses pharmacological potential because of its high content of quinolizidine alkaloids and flavonoids; however, there is little available information about its genotoxicity. We used the comet assay and staminal nuclei of Tradescantia (clone 4430) to evaluate the in vitro genotoxicity of 4 concentrations (0.01, 0.1, 0.5, and 1.0 mM) of alkaloid extracts of Lupinus mexicanus and Lupinus montanus, flavonoids of L. mexicanus, and commercial sparteine; nitrosodiethylamine was used as a positive control and untreated nuclei were used as a negative control. All concentrations of L. mexicanus and L. montanus showed significant genotoxic activity (P ≤ 0.05). A similar behavior was observed for flavonoid extracts of L. montanus except the 1.0 mM concentration. Sparteine showed genotoxic activity only at 0.5 mM. The order of genotoxicity of the compounds studied was as follows: L. mexicanus > L. montanus > flavonoids of L. montanus > sparteine. There is evident genotoxic activity in the compounds that were studied, particularly at lower concentrations (0.01 and 0.1 mM). Given the limited information about the genotoxicity of the compounds of L. mexicanus and L. montanus, further studies are necessary.

Comminuted simultaneous bilateral tibial tubercle avulsion fractures: a case report

A 16-year-old male had simultaneous bilateral tibial tubercle avulsion fractures after making a sudden stop while running at full speed. The left knee injury (type V) was minimally displaced, was treated conservatively with closed reduction, and the patient recovered uneventfully. The right tibial tubercle injury was unusual. The tuberosity and anterior aspect of the proximal epiphysis remained as one, but there was severe intra-articular comminution posterior to the displaced tubercle fragment. The right knee injury (type III) required open reduction and internal fixation to reduce the apophyseal fragment and 2 intra-articular displaced fragments. The patient's recovery was complicated by a severe, persistent flexion deformity on the right side. Eventually, the patient required manipulation under anaesthesia, extensive continuous passive mobilisation and a turnbuckle extension splint. A residual 5-degree flexion deformity remained at 16 months post-injury. This case highlights the importance of identifying any intra-articular fragments, their careful anatomical reduction, and aggressive mobilisation when treating tibial tubercle avulsion fractures.

Intragraft cytokine expression in heart transplants with mild or no histological rejection

The study of pro-inflammatory cytokines produced in situ in heart allografts may help to understand the mechanisms of rejection and open new possibilities to control graft rejection.

METHODS

A total of 23 endomyocardial biopsies obtained from 16 transplanted patients treated with triple-drug therapy (azathioprine, prednisone, and cyclosporine) were studied. mRNA expression for tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-6, IL-10, IL-12, IL-15, transforming growth factor (TGF)-beta, and beta-actin was determined by reverse transcription polymerase chain reaction (RT-PCR) and Southern blotting. Semiquantitative analysis was done by establishing the ratio between densitometric integrated value of each cytokine with the beta-actin and correlated with the histopathologic findings.

RESULTS

Three groups of biopsies were determined according to the International Society for Heart and Lung Transplantation criteria: grade 0 (control group, n=12), grade 1A (sub-clinical rejection, n=6) and 'quilty effect' (n=5). An increased expression of mRNA for TNF-alpha and IL-6 (p=0.0091 and 0.0075, respectively) was found associated with rejection grade 1A episodes, mRNA for IL-1 beta was nonspecifically expressed in all the study groups, while IL-10 mRNA was not detected in any of the biopsies studied. mRNA for IL-12 and IL-15 was not associated with rejection. Interestingly, TGF-beta was not detected in any of the biopsies with the 'quilty pattern'.

CONCLUSION

The association of TNF-alpha and IL-6 mRNA in situ expression with mild histologically probed rejection episodes may be used in the monitoring of heart transplants.

Effect of ethanol on insulin-stimulated glucose uptake in the isolated rat diaphragm

Insulin-stimulated (0.16 and 2.56 nM) glucose uptake (GU) was studied in isolated rat diaphragms in the presence of ethanol (EtOH) 21, 42 and 84 mM as well as in diaphragms removed from rats orally treated with the drug (1.5 or 4.5 g/kg/day) for 10 or 30 days. In spite of inhibiting the base-line GU, the addition of EtOH to the incubation medium gave rise to a potentiation of the insulin effect. In the orally intoxicated series, the low-dose EtOH increased the response to 0.16 nM insulin after 10 or 30 days, no changes being observed in that induced by 2.56 nM insulin. On the other hand, the high-dose EtOH caused an increase of the base-line GU which remained practically unmodified in the presence of insulin. The precise molecular basis for these phenomena is unknown.

Development of the esophageal muscles in embryos of the sea urchin Strongylocentrotus purpuratus

Development of the esophageal muscles in embryonic sea urchins is described using light- and electron microscopy. The muscles develop from processes of about 14 cells of the coelomic epithelium that become immunoreactive to anti-actin at about 60 h (12-14 degrees C). Initially, each myoblast extends a single process with numerous fine filopodia around the esophagus. By 72 h the processes have reached the midline and fused with those from cells of the contralateral coelomic sac. Myoblasts begin to migrate out of the coelomic epithelium between 72 and 84 h. By 72 h the processes stain with the F-actin specific probe NBD-phallacidin. The contractile apparatus is not evident in transmission electron-microscopic preparations of embryos at 70 h, but by 84 h the contractile apparatus is present and the muscle cells are capable of contraction. Because the myoblasts migrate free of the coelomic epithelium and are situated on the blastocoelar side of the basal lamina, it is suggested that that they should be considered as a class of mesenchymal cells.

Mandibular advancement combined with horizontal advancement genioplasty for the treatment of obstructive sleep apnea in an edentulous patient. A case report

Orthognathic surgical procedures have been used in the past for the treatment of obstructive sleep apnea. The treatment becomes more complicated when the patient has edentulous upper and lower arches. A treatment plan that provided a good surgical result and resolution of all symptoms was devised for such a patient.

An ecdysteroid-induced alteration in the cell cycle of cultured Drosophila cells

The addition of physiological concentrations of the arthropod molting hormone 20-hydroxyecdysone results in the cessation of cell division in the Kc cell line of Drosophila melanogaster. Fluorometric mononitoring of the cell cycle reveals that treatment of the cells with hormone for 12 hr causes a G2 arrest. The dose-response curves are in agreement with those obtained for other hormonal effects in both the Kc line and the intact animal. In the continual presence of hormone, cells remain G2-arrested for approximately 100 hr, resuming division by 120 hr. Cells which have responded once to ecdysteroids and subsequently reentered the cell cycle are insensitive to hormonal restimulation. This lack of response has been correlated with, and is probably due to, the loss of ecdysteroid receptors in stimulated cells.