El ingreso a Biología: una propuesta para abordar la distancia entre la suposición y lo posible

El presente trabajo tiene por objetivo presentar para su análisis y discusión, la propuesta del área de Biología, del Curso Introductorio a la Facultad de Ciencias Naturales y Museo (UNLP). La sistematización del diagnóstico de los alumnos, representa el eje de la adecuación continua de la propuesta. Se desarrolló a lo largo de seis años (2004-2009) comparativos, para lo cual se diseñaron instrumentos de evaluación cuyos resultados fueran cuantificables y sistematizables. Dada la magnitud de las dificultades observadas, su sostenimiento y su progresivo incremento sabemos que el proceso de adaptación a la vida Universitaria en el contexto explicitado, representa un proceso que excede los tiempos de un trayecto de ingreso. En el grupo de alumnos ingresantes encontramos gran diversidad de intereses y de formación. Las dificultades estructurales que deben superar para abordar los contenidos de primer año son importantes y se refieren a todos los aspectos comprometidos en el proceso de enseñanza-aprendizaje. Se presentan la formulación de las clases desde una postura sistémica, que permite adecuarla continuamente a los cambios, que se suceden cada vez más rápido y a las variables emergentes de la propia institución universitaria. Los resultados obtenidos nos permiten definir Ingreso como un trayecto necesario de ser revisado para su adecuación continua en función de las problemáticas complejas inherentes a los alumnos.Trabajos del área Ciencias NaturalesDepartamento de Ciencias Exactas y Naturale

Prevalence of Proteinuria in Owned Dogs from Italy : a Multicentric Study

Even though proteinuria is related to different causes, when it is persistent and associated with inactive urinary sediment, it is primarily due to kidney disease. Early detection of proteinuria allows us to identify several pathological conditions. The aim of the study was screening a canine population not known as being proteinuric, by the urinary dipstick. The study was carried out in seven Italian veterinary clinics during a period of six weeks. Dogs were enrolled with no restriction of sex or age. Females in estrus, dogs with signs of genitourinary diseases, or those previously diagnosed with proteinuric nephropathy were excluded. Dogs were considered \u201cnonproteinuric\u201d (NP) in case of negative dipstick test or \u201csuspected proteinuric\u201d (SP), if positive at the dipstick. When possible, proteinuria was confirmed by UPC ratio. A total of 1156 dogs were evaluated: 414 were from northern Italy and 742 from southern Italy. Based on dipstick test, 655 (56.6%) dogs were NP, while 501 (43.3%) were SP. Among the NP dogs 225 out of 414 (54.3%) were in northern Italy and 430 of 742 (57.9%) in southern Italy. One hundred eighty-nine of 414 (45.7%) SP dogs were identified in northern Italy and 312 of 742 (42.1%) in southern Italy. No statistical difference was found between the North and the South of Italy. UPC was available in 412 out of 501 SP samples: proteinuria was confirmed in 263 (63.86%) samples. Results from our study showed a high percentage of suspected proteinuric dogs, apparently not affected by renal diseases, together with the absence of statistically significant differences based on geographical area

Evaluation and outcome of the delorme procedure in the treatment of rectal outlet obstruction.

PURPOSE: This study was designed to assess the results of the Delorme procedure in the treatment of patients with rectal outlet obstruction. METHODS: A descriptive retrospective study from October 1989 to October 1997 was undertaken. Thirty-four patients with an abnormal defecography documenting rectal outlet obstruction caused by internal rectal prolapse or a combination of internal rectal prolapse and rectocele were included in the study. RESULTS: Thirty-four patients (33 females) ages 35 to 82 (mean, 61.4) years were followed up for the duration of the study (mean follow-up, 43 months). Twenty-six patients (76.4 percent) reported a good to excellent overall result after the Delorme procedure. Eight patients (23.6 percent) reported fair to poor results. Symptomatic improvement was observed in 89.7 percent for patients who had incomplete evacuation, and in 88.5 percent of patients who had constipation. There was improvement in 78.6 percent of patients with bleeding per rectum, in 92.9 percent of patients with straining, and in 82.4 percent of patients with the need to manually assist in defecation by pushing in the perineum or vagina. Discontinuation of laxative use after the procedure was reported by 66.7 percent of patients. Improvement in the patients with some degree of incontinence was seen in 33.3 percent. Twelve patients (35.3 percent) experienced one or more complications. The procedure was performed in an outpatient setting in 71 percent of the patients. CONCLUSIONS: The Delorme procedure for the treatment of rectal outlet obstruction can be done with minimal morbidity, short hospital stay often in an outpatient setting, with good functional results, and with an overall patient satisfaction above 75 percent

Enteritis cystica profunda in Peutz-Jeghers syndrome. Report of a case and review of the literature.

The hereditary condition known as Peutz-Jeghers syndrome is characterized by mucosal pigmentation and gastrointestinal polyps. The polyps, usually pedunculated hamartomas, are significant only for the symptoms they cause. Intramural lesions also have been described with gross microscopic features that are often interpreted as malignant. Careful evaluation may show most of these lesions to be enteritis cystica profunda. These rarely diagnosed but benign tumors have very different implications for treatment and prognosis

Lipase-mediated production of defensive toxins in the marine mollusc Oxynoe olivacea

Metabolites related to caulerpenyne (1), a toxic sesquiterpene featured by two enol-acetate residues, play a major role in the chemical defence of both algae of the genus Caulerpa and a few molluscs of the order Sacoglossa. Here we report the direct evidence that cell-free preparations of Oxynoe olivacea, a Mediterranean sacoglossan, transform efficiently the algal metabolite 1 to oxytoxin-2 (3), the main defensive metabolite of the mollusc. The process implies two distinct hydrolytic activities, here named LIP-1 and LIP-2, able to operate either hydrolysis of the acetyl residue at C-1 or concerted elimination of the acetyl groups at C-4 and C-13. Incubation experiments with tissue homogenates of O. olivacea or with commercially available lipases suggest a two-step mechanism that involves, in vitro, an unstable metabolite characterized as preoxytoxin-2 (4). The course of the entire process can be easily monitored by reverse phase HPLC/ESI-MS, as well as by NMR measurements, which provides direct evidence of the enzymatic mechanism leading to the formation of this last compound (4). In agreement with the literature, both fresh and frozen tissues of Mediterranean Caulerpa prolifera also have the capability to transform 1 into aldehydic derivatives, namely oxytoxin-1 (2) and oxytoxin-2 (3), through hydrolysis of the acetyl groups. However, differently from experiments with mollusc homogenates, the conversion is not complete and caulerpenyne (1) can be detected in the algal suspension for a few hours. HPLC/ESI-MS monitoring of this transformation suggests that the hydrolytic route involves different activities in the mollusc and seaweed

First biosynthetic evidence on the phenyl-containing polyketides of the marine mollusc Scaphander lignarius

The biosynthesis of lignarenones 1 and 2, the major polyketides of the Mediterranean mollusc Scaphander lignarius is described. The process is primed by benzoic acid and requires acetate and propionate as extender units. The labeling pattern suggests PKS-like synthesis of an unusual E,Z,E-triene chain and origin of the benzoate unit from phenylalanine. 13C-13C NMR COSY has been used to establish the labeling positions due to incorporation of 13C2-acetate

The Lobos pond and its tributary: descriptive limnology with special reference to the plankton

Temporal and spatial variations of transparency, temperature, pH, conductivity, and plankton are described for the subtropical oligohaline Lobos pond (Buenos Aires province, Argentina) and its main tributary during a complete annual cycle. Morphometric and pluviometric data, as well as a brief revision of previous studies of pampasic ponds are given. Our results show that salts in the pond derived from its tributary, and that rainfall is the key factor in modifying the ecological conditions in the pond. 181 planktonic species, including several ticoplanctonic ones, were recorded; many of these are halophilous organisms. Discrimination was made between the species that dwell in the pond only, and those which have lotic origins. Numerically the phytoplankton is dominated by blue-green algae, while the green algae and diatoms are the most diversified groups. Copepods and rotifers are the most abundant zooplankters; while highest numbers of species were yielded by the latter and the ciliates.Se describe la variación espacial y temporal de la transparencia, la temperatura, el pH, la conductividad y el plancton en la laguna subtropical oligohalina Lobos (provincia de Buenos Aires, Argentina) y su afluente principal a lo largo de un ciclo anual. Se presentan datos morfométricos, de precipitaciones y una corta revisión de los estudios sobre lagunas pampásicas. Se determina que las sales son aportadas a la laguna por su afluente, que la amplitud de la variación de su concentración salina es mayor que la registrada previamente y que las lluvias son el principal factor de alteración de las condiciones ecológicas de la laguna. Dentro del plancton, incluyendo al ticoplancton, se registran 181 especies, muchas de las cuales son halófilas. Se discriminan las especies que son autóctonas de la laguna de aquellas que pueden tener origen lótico. El fitoplancton se encuentra dominado por las cianofitas en cantidad y por las clorofitas y dlatomeas en variedad, y el zooplancton por la abundancia de copépodos y rotíferos y la variedad de rotíferos y ciliados.Contribución científica Nº 443 del Instituto de Limnología "Raúl A. Ringuelet" (ILPLA).Instituto de Limnología "Raúl A. Ringuelet

New C16 fatty-acid-based oxylipin pathway in the marine diatom Thalassiosira rotula

An unprecedented series of C16 oxylipins (1–8) has been characterized from the marine diatom Thalassiosira rotula. Absolute stereochemistry of the major alcohols 2 and 3 was determined to be 9S by spectroscopic and chemical methods. All the described products are formally derived by unprecedented enzymatic oxidation of C16 fatty acids. Conversion of hexadeca-6,9,12-trienoic acid (C16:3 x-4) into 3 unequivocally established the occurrence of (at least) a specific 9S-oxygenase activity. To the best of our knowledge, the present data reveal for the first time the existence of an organic network of oxygenase-mediated transformations that require C16 fatty acids as substrates in living cells

Chemistry of oxylipin pathways in marine diatoms

Oxylipins are important signal transduction molecules widely distributed in animals and plants where they regulate a variety of events associated with physiological and pathological processes. The family embraces several different metabolites that share a common origin from the oxygenase-catalyzed oxidation of polyunsaturated fatty acids. The biological role of these compounds has been especially studied in mammalians and higher plants, although a varied and very high concentration of these products has also been reported from marine macroalgae. This article gives a summary of our results concerning the oxylipin chemistry of marine diatoms, a major class of planktonic microalgae that discourage predation from their natural grazers, zooplanktonic copepods, using chemical warfare. These apparently harmless microscopic cells produce a plethora of oxylipins, including short-chain unsaturated aldehydes, hydroxyl-, keto-, and epoxyhydroxy fatty acid derivatives, that induce reproductive failure in copepods through abortions, congenital malformations, and reduced larval growth. The biochemical process involved in the production of these compounds shows a simple regulation based on decompartmentation and mixing of preexisting enzymes and requires hydrolysis of chloroplast-derived glycolipids to feed the downstream activities of C16 and C20 lipoxygenases