The utility of selective partial neurectomy of the musculocutaneous nerve in children with bilateral spastic elbow.

PURPOSE: This study aims to determine the utility of selective partial neurectomy of the musculocutaneous nerve (MCN) in pediatric patients with bilateral spastic elbow. METHODS: A prospective, cross-sectional, case series study was performed in nine pediatric patients (four females and five males) with bilateral spastic elbow, all with a 11.4-year-old average age, where 18 selective partial neurectomies of the MCN were carried out. They were evaluated with goniometry of both spastic elbows at resting position and active amplitude, and staging spasticity employing the Modified Ashworth Scale (MAS) in the preoperative and postoperative period. The results are reported 1 year after surgery. RESULTS: The etiology of the spasticity was secondary to cerebral palsy in eight patients (88.8%) and in one patient (11.11%) secondary to traumatic brain injury. A clinical improvement was observed in goniometry comparing the preoperative and postoperative resting position, a mean preoperative of 44.38 degrees (SD ± 7.61) versus 98.05 degrees (SD ± 24.44), respectively, and preoperative active amplitude a mean of 86.55 degrees (SD ± 15.97) versus the mean postoperative of 47.33 (SD ± 17.86). A relevant decrease on the MAS after surgical intervention was observed, resulting from an average preoperative state according to MAS of 3.78 (SD ± 0.42) to a postoperative state according to MAS of 1.44 (SD ± 0.51), these changes being statistically significant (p ≤ 0.001). No postoperative complications were observed. CONCLUSIONS: Selective partial neurectomy of the MCN has shown good results in patients with bilateral spastic elbow in whom antispastic drugs and physical therapy have failed, and has prove permanent effects.

The Transcriptomic Landscape of Pediatric Astrocytoma.

Central nervous system tumors are the most common solid neoplasia during childhood and represent one of the leading causes of cancer-related mortality. Tumors arising from astrocytic cells (astrocytomas) are the most frequently diagnosed, and according to their histological and pathological characteristics, they are classified into four categories. However, an additional layer of molecular classification considering the DNA sequence of the tumorigenesis-associated genes IDH1/2 and H3F3A has recently been incorporated into the classification guidelines. Although mutations in H3F3A are found exclusively in a subtype of grade IV pediatric astrocytoma, mutations in IDH1/2 genes are very rare in children under 14 years of age. The transcriptomic profiles of astrocytoma in adults and children have been extensively studied. However, there is scarce information on these profiles in pediatric populations considering the status of tumorigenesis-associated genes. Therefore, here we report the transcriptomic landscape of the four grades of pediatric astrocytoma by RNA sequencing. We found several well-documented biological functions associated with the misregulated genes in the four grades of astrocytoma, as well as additional biological pathways. Among the four grades of astrocytoma, we found shared misregulated genes that could have implications in tumorigenesis. Finally, we identified a transcriptional signature for almost all grades of astrocytoma that could be used as a transcription-based identification method.

Functional outcome after cord detethering in fecally incontinent patients with anorectal malformations.

PURPOSE: Tethered cord (TC) occurs in 36% of patients with anorectal malformations (ARMs), for whom the benefit of detethering surgery remains unclear regarding bowel and/or bladder function. This study aimed to examine whether cord detethering could improve fecal and urinary incontinence in these patients. METHODS: This was a retrospective study of TC patients (>3 years old) with fecal incontinence and ARMs, who underwent detethering surgery between 2016 and 2020 and were followed up for at least 6 months. RESULTS: Of the 27 included patients, 55% had sacral ratios between 0.4 and 0.7, and in 37% it was < 0.4; the remaining 8% was over 0.7; 52% suffered from colonic hypermotility. After detethering surgery, partial fecal continence was achieved in five patients (18%); total fecal continence, in ten patients (37%); 12 (44%) remained fecally incontinent. Partial urinary continence was obtained in four cases (14%), and the number of patients with total urinary continence rose from 7 (25%) to 15 (55%). Lower extremity symptoms were also improved in 72% of the cases. Patients with colonic hypomotility were found to have a better functional outcome than those with colonic hypermotility (69% vs. 43%, respectively). CONCLUSION: Our study demonstrated that detethering surgery led to remarkably improved bowel and bladder control in ARM patients with fecal incontinence, which, surprisingly, was not associated with sacral ratio.

Phrenic nerve neurotization utilizing half of the spinal accessory nerve to the functional restoration of the paralyzed diaphragm in high spinal cord injury secondary to brain tumor resection.

The authors present a case of functional improvement of diaphragmatic paralysis in high spinal cord injury, performing a neurotization of the phrenic nerve with accessory spinal nerve hemisection. A C1-C2 injury of the spinal cord was diagnosed in a 12-year-old male, secondary to resection of a brainstem glioma. The patient did not have diaphragmatic motility at the moment that the mechanical ventilation was removed; however, he presented apnea. The patient underwent neurotization of the right phrenic nerve with the right spinal accessory nerve, 5 months after the injury and 6 months after nerve transfer; he had complete mobilization of the right hemidiaphragm, nevertheless persisted with paralysis of the left hemidiaphragm. This achievement reduced the use of mechanical ventilation during the day.

Brain Connectivity in Ateles geoffroyi: Resting-State Functional Magnetic Resonance Imaging of Working Memory and Executive Control.

The objective of this research was to describe the organization and connectivity of the working memory (WM) and executive control (EC) networks in Ateles geoffroyi in resting-state conditions. Recent studies have shown that resting-state activity may underlie rudimentary brain functioning, showing that several brain regions can be tonically active at rest, maximizing the efficiency of information transfer while preserving a low physical connection cost. Whole-brain resting-state images were acquired from three healthy adult Ateles monkeys (2 females, 1 male; mean age 10.5 ± SD 2.5 years). Data were analyzed with independent component analysis, and results were grouped together using the GIFT software. The present study compared the EC and WM networks obtained with human data and with results found in the literature in other primate species. Nine resting-state networks were found, which were similar to resting networks found in healthy human adults in the prefrontal basal portion and frontopolar area. Additionally, components of the WM network were found to be extending into the hypothalamus and the olfactory areas. A key finding was the discovery of connections in the WM and EC networks to the hypothalamus, the motor cortex, and the entorhinal cortex, suggesting that information is integrated from larger brain areas. The correlated areas suggest that many elements of WM and EC may be conserved across primate species. Characterization of these networks in resting-state conditions in nonhuman primate brains is a fundamental prerequisite for understanding of the neural bases underlying the evolution and function of this cognitive system.

Endoscopic ventriculo-cisterno-ventricular approach in the treatment of bilateral trapped temporal horn related to fungal infection in a child: case report and review of the literature.

INTRODUCTION: Focal hydrocephalus including trapped temporal horn (TTH), isolated lateral and fourth ventricles, is caused by obstruction and/or adhesion related to various etiologies. With the advent of the neuroendoscope, endoscopic procedures have become an alternative in selected cases. CASE REPORT: A 2-year-old male from a rural town in México was referred to our institution because of multiple supra- and infra-tentorial abscesses and hydrocephalus. The patient had progressive deterioration and developed bilateral trapped temporal horn related to multi-septated hydrocephalus, so we performed an endoscopic ventricular-cistern-ventriculostomy through a single right temporal burr hole. POSTOPERATIVE COURSE: Bilateral TTH and multi-septated hydrocephalus were effectively treated with a single external ventricular drainage (EVD) catheter, from the right temporal horn to the left temporal horn through the interpeduncular cistern; after clamping the EVD for 3 days with no evidence of hydrocephalus, the EVD was removed. The size of the ventricles remained stable afterwards, and no clinical or radiological evidence of hydrocephalus was observed after 3 months of follow-up. DISCUSSION: Endoscopic ventriculocisternostomy is effective in selected cases of TTH. We know that dilatation of the temporal horn widens the window between the anterior choroidal artery and optic tract superiorly, and the posterior communicating and CN III inferiorly, making the described procedure feasible, even in the approach to the contralateral side. Even though this is a rare condition, we believe it is a safe and effective option to eliminate multiple shunts and/or to reduce the number of catheters needed to treat bilateral THH related to multi-septated hydrocephalus.

[A front-of-pack labelling system for food and beverages for Mexico: a strategy of healthy decision-making.] / Sistema de etiquetado frontal de alimentos y bebidas para México: una estrategia para la toma de decisiones saludables.

The Mexican Ministry of Health requested the National Institute of Public Health to constitute a group of independent, free of conflict-of-interest academic experts on front-of-pack labelling (FOP). This group was instructed to created a positioning paper to contribute to the development of a FOP system for industrialized products that offers useful information for purchase decision making. This position paper uses the best available scientific evidence, and recommendations from experts of international organizations. The FOP proposal focuses on the contents of energy, nutrients, ingredients and components that if consumed in excess on the diet, can be harmful to people's health, such as added sugars, sodium, total fat, saturated fat and energy. The academic expert group recommends the implementation of a FOP that provides an easy way to quickly assess the quality of a product. It is essential that this FOP provides direct, simple, visible and easily understandable information.

La Secretaría de Salud solicitó al Instituto Nacional de Salud Pública la conformación de un grupo de expertos académicos en etiquetado de alimentos y bebidas, independientes y libres de conflictos de interés, que tuvieran la encomienda de emitir una postura para contribuir al desarrollo de un sistema de etiquetado frontal para productos industrializados que proporcione información útil para facilitar la decisión de compra. La postura utiliza la mejor evidencia científica disponible y recomendaciones de expertos convocados por organismos internacionales. Así, la propuesta de etiquetado frontal se centra en el contenido de energía, nutrimentos, ingredientes y componentes cuyo exceso en la dieta puede ser perjudicial para la salud, como azúcares añadidos, sodio, grasas totales, grasas saturadas y energía. El grupo recomienda implementar un etiquetado frontal que, de forma sencilla, permita evaluar de manera rápida la calidad de un producto al momento de realizar una compra; por ello, es indispensable que éste proporcione información directa, sencilla, visible y fácil de entender.

Expression of microRNAs in tumors of the central nervous system in pediatric patients in México.

PURPOSE: MicroRNAs were identified as molecules that participate in gene regulation; alterations in their expression characterize central nervous system (CNS). Information in pediatrics is scarce, so the objective of this work was to determine and then compare the patterns of expression of microRNAs in astrocytomas, ependymomas, and medulloblastomas, as well as in non-neoplastic brain. METHODS: Low-density arrays were utilized to evaluate 756 microRNAs in three samples of each type of tumor and non-neoplastic brain. The relative expression was calculated in order to identify the three microRNAs whose expression was modified notably. This was verified using RT-qPCR in more number of tumor samples. RESULTS: The microRNAs selected for testing were miR-100-5p, miR-195-5p, and miR-770-5p. A higher expression of miR-100-5p was observed in the astrocytomas and ependymomas compared to the medulloblastomas: on average 3.8 times (p < 0.05). MiR-770-5p was expressed less in medulloblastomas compared to astrocytomas four times (p = 0.0162). MiR-195-5p had a low expression in medulloblastomas compared to non-neoplastic cerebellum (p = 0.049). In all three tumor types, expression of miR-770-5p was lower than in non-neoplastic brain (p < 0.001). CONCLUSIONS: These microRNAs may represent potential markers in these tumors.

Brachmann-Cornelia de Lange syndrome with a papilloma of the choroid plexus: analyses of molecular genetic characteristics of the patient and the tumor. A single-case study.

PURPOSE: A 10-month-old girl with a Brachmann-Cornelia de Lange syndrome and a choroid plexus papilloma of the brain was studied at the Hospital Infantil de México Federico Gómez (HIMFG) in Mexico City. METHODS AND RESULTS: Presumptive papilloma of the third ventricle was evidenced on CT and MR images and removed. Pathological analysis confirmed its origin. A posterior radiosurgery was required due to a tumor relapse. Karyotypes (GTG bands) of the patient and her parents undertaken at HIMFG were normal. Array comparative genomic hybridization (array CGH) analyses of blood DNA of the patient and her parents carried out at BlueGnome's Laboratory in Cambridge, UK, set in evidence amplification of genes SPNS2, GGT6, SMTNL2, PELP1, MYBBP1A, and ALOX15 in chromosome 17p of the patient. Since MYBBP1A is a proto-oncogene and ALOX15 participates in the development of cancer and metastases of tumors, further fluorescent in situ hybridization (FISH) analyses of these two genes were implemented at HIMFG. Amplification of the two genes was found in the tumor of the case under study but not in an unrelated papilloma of the choroid plexus. DISCUSSION: Further analyses of the association of choroid plexus papillomas with disorders of psycho-neural development and its relationship to molecular genetic modifications at chromosome 17p are now under way at HIMFG.

The cytotoxic effect of 2-acylated-1,4-naphthohydroquinones on leukemia/lymphoma cells.

Here, we tested seven 2-acylated-1,4-hydronaphthoquinones for their cytotoxic effects on a panel of cancer lymphoma/leukemia cells and compared to a non-cancer origin cell line. Several naphthohydroquinones exhibited selective cytotoxic effects on lymphoma/leukemia cells with lowest activity on non-cancer cells. The mode of cell death induced by an acylated naphthohydroquinone, which has a long alkyl chain, was found to be via apoptosis. Furthermore, the naphthohydroquinone provoked mitochondria depolarization and activation of its downstream effector, caspase-3, thus implicating the intrinsic apoptotic pathway as its mechanism to exert cell death.

Epigenetic modifications in cell lines of human astrocytoma differentially regulate expression of apoptotic genes.

OBJECTS: Epigenetic alterations, known as epimutations, act by deregulating gene expression. These epimutations are reversible through the action of chromatin modifiers such as DNA methylation (DNA-met) and histone deacetylases (HDAC) inhibitors. The present study evaluated the effect of 5-azacitidine (5-aza) and sodium butyrate (NaBu) as inhibitors of DNA-met and HDAC, respectively, in the expression of genes involved in apoptosis. METHODS: D54-MG, U373-MG, and T98G cell lines were exposed to 8 mM of NaBu and 12 µM of 5-aza, as well as a combination of both, for 24 h. The expression of the Bcl-2, Bak-1, Bax, Caspase-3, and Caspase-9 genes was assessed by RT-PCR. RESULTS: They show that the Bcl-2, Caspase-3, and Caspase-9 genes were not expressed by the U373-MG and T98G lines, and that the D54-MG line did not express Bak-1. After treatment, however, these cell lines expressed all of the genes due to the effect of 5-aza on Bak-1 in D54-MG and Caspase-9 in T98G, which suggests repression by DNA-met. Meanwhile, Bcl-2, Caspase-3, and Caspase-9 were in the U373-MG and T98G lines expressed after NaBu treatment. The effect of 5-aza induced an increase in the expression of Bax and Bcl-2, while NaBu produced a similar effect on the Bak-1 and Bax genes. CONCLUSIONS: Results reveal that histone deacetylation is the principle mechanism for repressing these genes and that their basal expression is regulated primarily by this form of histone modification.

Reductions in the expression of miR-124-3p, miR-128-1, and miR-221-3p in pediatric astrocytomas are related to high-grade supratentorial, and recurrent tumors in Mexican children.

PURPOSE: Astrocytomas are the most frequent type of tumor of the central nervous system in children. Hence, it is important to describe markers that may improve our understanding of their behavior. Mature microRNAs (miRNAs) may be such biological markers. They are small molecules of RNA that regulate gene expression post-transcriptionally. Due to their importance in cancer, the objective of the present study was to determine the profile of expression of precursor and mature forms of miR-124-3p, miR-128-1, and miR-221-3p using RT-qPCR in pediatric samples. METHODS: A total of 57 astrocytomas embedded in paraffin were selected. As controls, the study included 13 samples of normal brain tissue. RESULTS: Three of eight miRNAs were selected after a preliminary screening. All the miRNAs showed higher levels of expression in normal brain tissue. The expression of miR-124-3p and miR-128-1 decreased in astrocytomas than in normal brain tissue in all grades (p < 0.05 in both cases), and this reduction was most evident in GIV (407- and 1,469-fold, respectively); however, the expression of the precursor forms pre-miR-128-1 and pre-miR-221 was higher in GIV (3.5-fold) than in GI. The levels of miR-128-1 were higher in infratentorial tumors than in supratentorial cases (p = 0.006). Finally, the expression of miR-221-3p was higher in non-recurrent tumors and live patients (p = 0.0185 and p = 0.0004, respectively). CONCLUSIONS: The low expression of these miRNAs may constitute a potential marker of astrocytomas that correlates with localization, possibly due to alterations in the maturation processes of these miRNAs that produced low mature forms in patients with recurrent pediatric astrocytomas.

Image Guided Interpedicular Screw Placement Simulation System for Training and Skill Evaluation. Proof of Concept.

BACKGROUND: The SpineST-01 system is an image-guided vertebrae cannulation training system. During task execution, the computer calculates performance-based metrics displaying different visual perspectives (lateral view, axial view, anteroposterior view) with the position of the instrument inside the vertebra. Finally, a report with the metrics is generated as performance feedback. METHODS: A training box holds a 3D printed spine section. The computer works with 2 orthogonally disposed cameras, tracking passive markers placed on the instrument. Eight metrics were proposed to evaluate the execution of the surgical task. A preliminary study with 25 participants divided into 3 groups (12 novices, 10 intermediates, and 3 expert) was conducted to determine the feasibility of the system and to evaluate and assess the performance differences of each group using Kruskal-Wallis analysis and Mann-Whitney U analysis. In both analyses, a P value ≤ 0.05 was considered statistically significant. RESULTS: When comparing experts versus novices and all 3 groups, statistical analysis showed significant differences in 6 of the 8 metrics: axial angle error (°), lateral angle error (°), average speed (mm/second), progress between shots (mm), Time (seconds), and shots. The metrics that did not show any statistically significant difference were time between shots (seconds), and speed between shots (mm/second). Also, the average result comparison placed the experts as the best performance group. CONCLUSIONS: Initial testing of the SpineST-01 demonstrated potential for the system to practice image-guided cannulation tasks on lumbar vertebrae. Results showed objective differences between experts, intermediates, and novices in the proposed metrics, making this system a feasible option for developing basic navigation system skills without the risk of radiation exposure and objectively evaluating task performance.

Expression of histone acetylases p300 and PCAF in pediatric astrocytomas.

OBJECTS: The protein 300 (p300) and p300/CBP-binding protein-associated factor (PCAF) are enzymes with histone acetyltransferase (HAT) activity, a function that can become deregulated in different tumors and affect biological responses. METHODS: Due to the lack of information on the deregulation of these HATs in pediatric tumors, this study evaluated the expression of both the mRNA and proteins of p300 and PCAF in 54 samples of pediatric astrocytomas embedded in paraffin. RESULTS: PCAF was not expressed in normal brain tissue. In grade I tumors, the expression of p300 (1.1 ± 0.1) and PCAF (1.2 ± 0.11) was greater than those observed in grade III tumors: 0.72 ± 0.15 for p300 and 0.55 ± 0.11 for PCAF, and grade IV tumors: 0.74 ± 0.13 for p300 and 0.55 ± 0.13 for PCAF (p < 0.05). Immunohistochemical staining revealed the same tendency towards a decrease in the expression of the protein as the degree of clinical severity increased. Patients with recurrent grades I, III, and IV tumors had the highest levels of PCAF, compared to those who showed no recurrence (p < 0.05). CONCLUSIONS: This work describes and confirms that these HATs play important roles in regulating genes and in the biological behavior of pediatric astrocytomas.

Targeting an essential Plasmodium cold shock protein to block growth and transmission of malaria parasite.

Cold shock proteins are characterized by the presence of one or more cold shock domains that bestow them with nucleic acid binding ability. Although cold shock proteins are well characterized in bacteria, plants and humans, there is no information on their existence and role in malaria parasite. Here, we have identified and delineated the function of a cold shock protein of Plasmodium falciparum (Pf) 'PfCoSP'. We demonstrate that PfCoSP exhibits nucleic acid binding properties and regulates gene expression. PfCoSP promotes microtubule assembly by interacting with Pf α/ß tubulin. We identified a human cold shock protein LIN28A inhibitor 'LI71' as a binding partner of PfCoSP which inhibited PfCoSP-DNA and α/ß tubulin interactions and, also inhibited the development of asexual blood stages and gametocyte stage of malaria parasite. Because PfCoSP is essential for parasite survival, characterization of its interacting partners may form the basis for development of future anti-malarials.

Single sagittal craniosynostosis surgical treatment with the "Peau d́ours" technique. Single-center experience in Mexico.

Scaphocephaly (SC) is defined as an elongation of the anteroposterior axis of the skull resulting from the abnormal fusion of the sagittal suture. This study describes the "Peau d'ours" technique and results for correcting SC. We conducted a consecutive and retrospective analysis of patients treated from 2011 to 2016. We evaluated the gender, age, and surgical outcomes. A total of 53 patients were enrolled with a mean age of 19 months old. The advantages of this technique are healthy coronal and lambdoid suture preservation and symmetrical parietal bone flap opening. This technique is safe and simple to reproduce, allowing good surgical outcomes with a low incidence of secondary craniosynostosis. This technique is ideal for patients older than six months old.

Integration of Comprehensive Metrics into the PsT1 Neuroendoscopic Training System.

OBJECTIVE: Metric-based surgical training can be used to quantify the level and progression of neurosurgical performance to optimize and monitor training progress. Here we applied innovative metrics to a physical neurosurgery trainer to explore whether these metrics differentiate between different levels of experience across different tasks. METHODS: Twenty-four participants (9 experts, 15 novices) performed 4 tasks (dissection, spatial adaptation, depth adaptation, and the A-B-A task) using the PsT1 training system. Four performance metrics (collision, precision, dissected area, and time) and 6 kinematic metrics (dispersion, path length, depth perception, velocity, acceleration, and motion smoothness) were collected. RESULTS: For all tasks, the execution time (t) of the experts was significantly lower than that of novices (P < 0.05). The experts performed significantly better in all but 2 of the other metrics, dispersion and sectional area, corresponding to the A-B-A task and dissection task, respectively, for which they showed a nonsignificant trend towards better performance (P = 0.052 and P = 0.076, respectively). CONCLUSIONS: It is possible to differentiate between the skill levels of novices and experts according to parameters derived from the PsT1 platform, paving the way for the quantitative assessment of training progress using this system. During the current coronavirus disease 2019 pandemic, neurosurgical simulators that gather surgical performance metrics offer a solution to the educational needs of residents.

Hydrocephalus in Mexican children with Coccidioidal Meningitis: Clinical, serological, and neuroimaging findings.

BACKGROUND: Coccidioidal meningitis (CM) is a fungal infectious disease that rarely affects children. Even in endemic areas, coccidiomycosis rarely affects the pediatric population. However, 40% of affected children develop hydrocephalus. Here, we describe the clinical, serological, and neuroimaging findings in a series of Mexican children admitted to our neurosurgical service with hydrocephalus and subsequently diagnosed with CM. METHODS: We report a prospective series of pediatric patients with hydrocephalus secondary to CM in an endemic area at the north of Mexico. Our report includes children with CM who were hospitalized from 2015 to 2019 in a regional hospital in Torreón, Coahuila. Clinical evolution was monitored for 1 year after hospital discharge. RESULTS: Our series include five children with CM (2-17-years-old, three female), who were hospitalized for hydrocephalus and developed intracranial hypertension. The most frequent neuroimaging findings were leptomeningeal enhancement (5/5) and basal arachnoiditis (4/5), followed by asymmetric hydrocephalus (3/5), abnormalities in fourth ventricle morphology (3/5), and cerebral vasculitis (2/5). CM was diagnosed by positive serology or pathology studies. All children were initially managed with fluconazole and a shunt was placed for management of hydrocephalus. Four patients recovered without permanent neurological deficits and one subject developed persistent vegetative state. One year after hospital discharge, none of the subjects died. CONCLUSION: This series contributes to the limited number of pediatric CM cases reported in the literature, and describes neuroimaging findings in the pediatric population. The cases here presented show that the identification of Coccidioides as causal agent in pediatric meningitis is crucial for targeted treatment and can affect dramatically neurological prognosis. Furthermore, our report stresses that even in endemic areas pediatric coccidiomycosis represents a diagnostic challenge, which is further exacerbated by the limited availability of resources in these regions. Therefore, a positive immunoglobulin G by enzyme immunoassay is enough for diagnosis of CM in endemic areas without access to CF.

Effect of lixiviated sediments affected with treated water on Selenastrum capricornutum, Printz and Origanum vulgare L.

Xochimilco is an area of Mexico City fulfilling important ecological functions. However, the water of the canal network in the lacustrine zone of Xochimilco is supplied by the water treatment plants of the city, implying a risk of accumulated contaminants in the sediments. This study reports the effect of lixiviates obtained from sediments collected in the canals of Xochimilco on the growth of the alga Selenastrum capricornutum and the angiosperm Origanum vulgare. Three factors were tested: (a) water source in terms of the effluent from the two water treatment plants (urban waste-water, located at Cerro de la Estrella (CE) and urban-rural waters at San Luis Tlaxialtemalco (SLT); (b) sampling season (January, dry season; May and September, rainy season; and (c) distances from the water discharge point in the Xochimilco's main canal (5200 and 1000 m for CE, and 0, 200 m for SLT). The chemical water properties analyzed were: pH, electrical conductivity, N-NO(3), N-NH(3), N(Total), P-PO(4) and P(Total). The alga was more sensitive to the contaminants than O. vulgare, showing growth inhibition of 93-100%. The effect of sampling season on the inhibition of algal growth was ordered as follows: September > May > January. Lixiviates obtained from sediment samples 200 and 1000 m from the main point of water discharge caused a higher algal growth inhibition than the samples obtained at the source point. Lixiviate promoted the growth of seedlings of O. vulgare.