Otto anni di laboratorio didattico nella chimica

pp.142-15

Studien zur kristallographischen Phasierung von Proteinen: Substruktur-Validierung und MAD-phasierte Elektronendichtekarten bei atomarer Auflösung

Die Röntgen-Kristallographie ist eine der wichtigsten Methoden der Strukturbiologie.Die Verfügbarkeit Schweratom-derivatisierter Proteine ermöglicht die Anwendung des kristallographischen MAD-Strukturlösungsverfahrens. Das Vorhandensein atomar aufgelöster Strukturdaten erlaubt hierbei detaillierte Aussagen über Reaktionsmechanismen von Enzymen. Aldose Reductase gehört zu einer Klasse von Enzymen, die Glucose zu Sorbitol reduzieren. Die Inhibierung des Enzyms ist relevant fuer die Behandlung von Diabetes-Folgesymptomen.In der vorliegenden Dissertation wurde die Struktur von Aldose Reductase mittels der MAD-Methode bestimmt und eine Strukturfeinerung bei 0.9 Angström Auflösung wurde mittels der experimentell (MAD-) phasierten Elektronendichtekarte bestätigt. Dabei konnten vor allem strukturelle Fehlordnungen und Wasser-Netzwerke detailliert analysiert werden.Weiterhin behandelt die vorliegende Dissertation die Entwicklung und Anwendung des Computerprogramms SitCom, welches Schweratom-Substrukturen von Proteinen, die wichtige Zwischenergebnisse der MAD- (und anderer) Methoden darstellen, systematisch vergleicht und somit einen nicht unerheblichen Beitrag zur Verbesserung der makromolekularen Strukturlösung darstellt. Die Anwendung des Programms lieferte nützliche Aussagen über empfohlene Strategien beim Gebrauch der MAD-Methode.X-ray crystallography is one of the most important methods in structural biology. The availability of heavy atom derivatives of proteins facilitates the application of the crystallographic MAD structure solution technique. Structural data of atomic resolution allow detailed statements about reaction mechanisms of enzymes. Aldose reductase belongs to a class of enzymes reducing Glucose to Sorbitol. The inhibition of this enzyme is relevant for the treatment of symptoms resulting from diabetes mellitus.In the present thesis, the structure of Aldose Reductase was determined by means of the MAD method. A structure refinement result at 0.9 Angstrom was confirmed with the experimental (MAD) electron density map. Thereby, multiple amino acid conformations and water networks were analyzed in detail.Furthermore, the thesis is concerned with the development and application of the software SitCom, which compares different heavy atom substructures of proteins systematically. The substructures are very important intermediate results of the MAD (and other) methods. Thus, SitCom contributes to the improvement of macromolecular structure solution. The application of the program yielded useful statements about recommended strategies when using the MAD technique

REVISION OF THE OSTRACODE SUBGENUS PALEOBLITACYTHEREIS BENSON, 1977

The genus Oblitacythereis, type species Oblitacythereis (Oblitacythereis) mediterranea Benson, 1977, and the subgenera Oblitacythereis and Paleoblitacythereis are well defined by Benson (1977), who designated Carinocythereis ruggierii Russo, 1966 as type species of Paleoblitacythereis. The specimens figured and described as Carinocythereis ruggierii by Benson (1977), however, clearly differ from Russo's species, and coincide well with Oblitacythereis sp. 3 Russo & Bossio, 1976, as stated by Bonaduce & Russo (1985). As a consequence of this misidentification the subgenus Paleoblitacythereis is subject to uncertainty and potential instability. The type species designated by Benson should be considered as a new nominal species and Carinocythereis ruggierii Russo, which actually belongs to Paleoblitacythereis, should be revised. The study of well-preserved specimens from some Miocene formations in southern Italy prompts the author to propose herein a systematic revision of the Italian representatives of the subgenus Paleoblitacythereis. Three species are discussed. These are: Oblitacythereis (Paleoblitacythereis) ruggierii (Russo, 1966), Oblitacythereis (Paleoblitacythereis) bossioi n. sp. ( = Oblitacythereis sp. 3 Russo & Bossio, 1976), here proposed as the new nominal type species of Paleoblitacythereis and, finally, Oblitacythereis (Paleoblitacythereis) apula n. sp., described as new. The systematic notes of each species are given with the bio-chronostratigraphical distribution resulting from the present study together with some palaeoecological remarks.&nbsp

Biocombustibili da oli alimentari

La nuova tendenza nell’apprendimento delle scienze integrate prevede che il laboratorio diventi il luogo in cui gli studenti possano acquisire abilità nell’organizzarsi autonomamente per assimilare nuove conoscenze. Ciò comporta un’efficace pianificazione interdisciplinare, ad es. tra insegnanti di biologia, chimica e fisica, che dia maggior libertà ai discenti, fatti salvi qualità e rigore. Le attività hanno come tema i biocombustibili, in particolare il biodiesel. Partendo dalla sua produzione in laboratorio, il modulo continua con l’analisi di alcune proprietà del prodotto rispetto a quelle del biodiesel standard. Si propongono letture e discussioni al fine di sviluppare la consapevolezza sia dei vantaggi dell’uso dei biocombustibili, che dei fattori che maggiormente contrastano l’espansione delle bioenergie.can achieve the skill to organise their activities and assimilate new knowledge. This is possible if a good interdisciplinary planning, i.e. between teachers of biology, chemistry and physics, are carefully organised to give learners free hand while maintaining quality and rigour. Activities concern biofuels, particularly biodiesel. Starting from the production of biodiesel in the chemistry lab, the module develops by comparing some properties of product with those of standard biodiesel. Reading passages and debates are proposed in order to make students aware of the advantages derived from the use of biofuels and the factors which mainly oppose the expansion of bioenergy

I grassi in casa. Dagli oli da frittura al sapone di Marsiglia

I grassi, che appartengono alla classe dei “lipidi”, sono presenti in natura e costituiscono uno dei macronutrienti del corpo umano, si trovano dunque nei cibi in gran quantità. Essi costituiscono la maggior riserva energetica per gli esseri viventi, ma presentano altre caratteristiche, tanto che oltre ad essere presenti in cucina, si utilizzano anche in particolari tipi di industria (ad es. saponi). Le autrici, partendo dagli usi alimentari dei grassi, ne descrivono prima alcune caratteristiche e ne studiano successivamente il comportamento chimico che ne consente altri usi. Completano l’articolo alcune esperienze didattiche laboratoriali effettuate in classi di scuola secondaria di 1° e 2° grado.Fats, which belong to the subgroup of lipids, are found in nature and they constitute one of the macronutrients indispensable to the human body in addition to carbohydrates and proteins. They are are present in great amount in food. Fats are the main store of energy for living organisms, but they also have other characteristics that allow their use in industry (i.e. soaps factory). This article, which starts to describe the typical uses of fats as nutrients, shows a series of chemical characteristics and behaviours to explain the importance of this molecules also in other contexts. Finally, it provides examples of teaching lab activities which have been conducted by authors in classes of learners aged between thirteen and sixteen years old

La chimica in cucina: emulsioni, sospensioni, gel

La cucina è il primo laboratorio di chimica e non è un caso che spesso i chimici siano ottimi cuochi. Una schiuma soffice, una gelatina, la giusta scelta della temperatura o del recipiente di cottura si basano su fenomeni chimico-fisici che, se osservati con consapevolezza, rendono migliori i cibi e “scientificamente competente” chi li cucina. Partendo da attività tipicamente culinarie, le autrici suggeriscono degli spunti da sviluppare in unità di apprendimento di chimica per lo studio degli stati dispersi: emulsioni, schiume, transizioni sol/gel, ecc. Data la vastità degli argomenti, esse hanno scelto di focalizzare le attività soprattutto su applicazioni nei glucidi e dei protidi. Una parte finale riguarda esempi di “chimica in un uovo” e di “cucina molecolare”.The kitchen is the first chemistry laboratory: actually, a lot of chemists are good cooks. A soft foam, a jelly, the right baking temperature or the choice of the right pots are examples of experiences based on chemical-physical phenomena. Their careful analysis leads us to be better cooks as well as better “scientific experts”. Starting from typical cooking activities, an input for chemistry learning centered on units is given, specifically on disperse phases as emulsions, foams, sol/gel transitions and so on. Considering the huge amount of topics, the focus is on activities concerning carbohydrates and proteins. The article finally provides examples of “chemistry into an egg” and “molecular cooking”.Fondazione CRTriest

MIDDLE MIOCENE OSTRACODS FROM THE SALENTINE PENINSULA

The ostracod faunas of the S. Caterina and S. Maria al Bagno sections (Salentine Peninsula, Apulia) were studied. These sections comprise the lower and middle levels of the Pietra Leccese formationand range collectively from the uppermost Burdigalian or the lower Langhian to the middle Serravallian. Forty-one species, belonging to twenty-seven genera were identified. Nineteen species known previously are illustrated and discussed; six (Carinocythereis messapica n. sp., Celtia multicostata n. sp., Cytherella obesa n. sp., Cytherella polygonalis n. sp., Cytherella salentinensis n. sp. and Cytherelloidea ? rectangularisn. sp.) are described as new, and two are left in open nomenclature. The stratigraphic distribution of a remarkable number ofshelf ostracod species,known previously from the Upper Miocene upwards, includes also part of the Middle Miocene.&nbsp

Auto-aplicação de insulina em crianças portadoras de diabetes mellitus tipo 1

The present descriptive study had the goals of characterizing type 1 diabetic children, according to socio-demographic variables and identifying the difficulties related to insulin self-management and home control. 34 type 1 diabetic children were interviewed at a big hospital. Results showed that 82.4% of children were white, 61.8% were female and 54.1% were from nine to eleven years of age, 67.7% were catholic, and 64% had the illness for 3 years. 35.3% of them learned insulin management with their mothers and 32.3% follow a schedule regarding insulin self-administration. Difficulties to perform home control are related to the available resources and lack of information. Results show the need for a planned work integrated by a multiprofessional team and directed to the children whose characteristics meet the mentioned aspects, considering their interdependence and aiming at achieving a successful careb.Estudio de naturaleza descriptiva que tiene por objetivos caracterizar el niño diabético tipo 1, de acuerdo con las variables demográficas e identificar las dificultades relacionadas a la auto-aplicación de insulina y su control domiciliario. Fueron entrevistados 34 niños diabéticos tipo 1, en un hospital de gran porte. Los resultados obtenidos muestran que son niños blancos (82,4%), mujeres (61,8%), edad entre nueve Y once años (54,1%), católicos (67,7%), son portadores de la enfermedad por tres años (64,3%). Aprendieron a administrarse la insulina con las madres (35,3%), realizan rotación para auto-aplicación (32,3%). Las dificultades para realizar el control domiciliario están relacionadas con los recursos disponibles y con la falta de información. Los resultados indican la necesidad de un trabajo planeado e integrado por el equipo multiprofesional que atienda cada aspecto abordado, observando su independencia para el éxito del cuidado al niño diabético tipo 1.Estudo de natureza descritiva que tem por objetivos caracterizar a criança diabética tipo 1, segundo as variáveis sócio-demográficas e identificar as dificuldades relacionadas a auto-aplicação de insulina e controle domiciliar. Foram entrevistadas 34 crianças diabéticas tipo 1, em um hospital de grande porte. Os resultados obtidos apontam que as crianças são brancas (82,4%), feminina (61,8%), idade entre nove e onze anos (54,1%) católicas (67,7%), são portadoras da doença há três anos (64,3%). Aprenderam a administrar a insulina com as mães (35,3%), realizam rodízio para auto-aplicação (32,3%). As dificuldades para realizar o controle domiciliar estão relacionadas aos recursos disponíveis e a falta de informação. Os resultados indicam a necessidade de um trabalho planejado e integrado da equipe multiprofissional a criança que atenda a cada aspecto abordado, observando a sua independência para o êxito do cuidado à criança diabética tipo 1

Erythromycin for prokinesis: imprudent prescribing?

Problems with antibiotic resistant bacteria are increasing in the hospital and particularly in the intensive care unit. Methicillin-resistant Staphylococcus aureus, Acinetobacter baumanii and extended spectrum beta-lactamase producing Gram-negative bacilli constitute a therapeutic and infection control challenge. Early enteral feeding improves survival in patients in the intensive care unit. Prokinetic agents are routinely used in patients with inappropriate gastrointestinal motility. The use of erythromycin at sub-therapeutic doses as a prokinetic agent is a cause of concern for the following reasons: it can increase the emergence and spread of antibiotic resistance and the likelihood of Clostridium difficile disease. The use of an antibiotic as a prokinetic agent does not constitute prudent antimicrobial prescribing and should be avoided. Alternative agents, whenever possible, should be used