Il docenti dell’Università di Groningen (Paesi bassi) Bauke Dijkstra e Lubbert Dijkhuizen hanno decifrato la struttura e il meccanismo funzionale dell’enzima glucansucrase, responsabile della placca dentale che attacca i denti. Questa scoperta stimola l’identificazione delle sostanze che inibiscono l’enzima. Basta infatti aggiungere tale sostanza al dentifricio, o anche ai dolci, e la carie sarà un problema del passato. I risultati della ricerca sono stati pubblicati questa settimana sulla rivista Proceedings of National Academy of Sciences (PNAS).
I ricercatori dell’Università di Groningen hanno analizzato il glucansucrase dal batterio acido lattico Lactobacillus reuteri, che è presente nella bocca dell’uomo e nel tratto digestivo. I batteri usano l’enzima glucansucrase per convertire lo zucchero del cibo in lunghe catene di zuccheri appiccicosi. Usano questa specie di “colla” per attaccarsi allo smalto dei denti, diventando così la causa principale della carie dentaria, in concomitanza con il batterio Streptococcus mutans, che lo utilizza. Una volta attaccati allo smalto dei denti, questi batteri fermentano gli zuccheri liberando gli acidi che dissolvono il calcio nei denti. In questo modo si sviluppa la carie.
L’utilizzo della cristallografia delle proteine, ha permesso ai ricercatori di chiarire le tre dimensioni (3D) della struttura dell’enzima. Essa ha così rivelato che il meccanismo di ripiegamento delle proteine è unico. I vari domini dell’enzima non sono formati da una singola catena lineare di amminoacidi, ma da due parti che si assemblano attraverso una struttura a forma di U della catena.
Il disfacimento della struttura 3D ha fornito ai ricercatori un quadro dettagliato sul meccanismo funzionale dell’enzima. Esso scinde il saccarosio in fruttosio e glucosio e quindi aggiunge la molecola di glucosio ad una catena di zucchero in crescita. Finora la comunità scientifica ipotizzava che entrambi i processi fossero eseguiti da diverse parti dell’enzima. Tuttavia, il modello creato dai ricercatori di Groningen ha rivelato che entrambe le attività si svolgono nello stesso sito attivo dell’enzima.
Dijkhuizen si aspetta che gli inibitori specifici per l’enzima glucansucrase possano aiutare a prevenire la fissazione dei batteri allo smalto dei denti, ma ulteriori ricerche sul meccanismo funzionale della struttura e sull’enzima sono essenziali per lo sviluppo di tali inibitori. Finora la ricerca non ha avuto successo, ma se in futuro gli inibitori del glucansucrase potranno essere aggiunti al dentifricio e collutorio, o persino nei dolci, le carie potrebbero essere definitivamente sconfitte. L’uso dello spazzolino, in ogni caso, resterà sempre necessario per garantire che il meccanismo funzioni a dovere.
[Fonte: Sciencedaily]
Manufacturing Steps
PRODUCTION CAPABILITIES
Ajram Industries is an employee owned company of Craftsmen and has got a good reputation for quality and reliability. Our significant manufacturing steps are being described here-under briefly:
1- MATERIAL USED: Always a best quality stainless steel material is purchased from steel manufacturers. Two kinds of series i.e. 300, 410 and 420 of stainless steel is used for production of Dental Instruments.
2- MATERIAL TESTING: The purchased raw material is thoroughly tested under PQA. authority. A rigid quality control policy is being adopted before releasing to production. This test is taken to check the standard of steel as per desired specifications and is considered the most important factor of our business.
3- FORGING & HAMMERING: After testing, the stainless steel strips/bars are divided into different sizes as per our requirements and our highly experienced craftsmen are specialized in forging (Hot/Cold Drop) to perform all standard press operations in forming and deep drawing of all type of instruments. We anneal the forging and prepare for the milling process.
4- MACHINE & TOOL WORK: Our highly skilled technicians have a great knowledge about machine milling process. We form accurately male/female portion of box-joint forceps, as well as, serrations/ retches in uniformity. We are equipped to mill, drill, bore turn and grind all type of metals. We have in house facility of custom tool and die production, maintenance and repair.
5- FILLING: We are specialized in hand–made fabrication. First, we assemble male/female portion after setting/adjusting of Extracting Forceps and Scissors, tips, serrations, ratches in uniformity and file precisely to make it semi-finish under strictly quality control specifications. We are now moving from basic hand manufacturing techniques to mechanization to production run.
6- HEAT TREATMENT: All instruments are being tempered maintaining “Rock-Well Hardness” for Extracting Forceps & Retractor 45º to 50º degree and Scalar, Gauges and Scalpel 50° to 55º degree. A test is taken to check the hardness after tempering of each lot to maintain the uniformity and, before proceeding further, we clean all instruments by various chemicals. In addition, we will buy specialized Q/C equipment in near future to meet special customer Q/C. specifications.
7- RIVETING & WELDING: We perform a wide variety of assembly operations from prototype quantities to production run. We rivet precisely each instrument such as, Extracting Forceps & Retractor, etc. But, for some kind of instruments, we use spot welding.
8- GRINDING & POLISHING: For precise grinding and excellent finish, we specialize in applying polishing wheels to belts to improve the overall finish in high uniformity utilizing best of polishing luster. We use electro-plating plants to polish serrations/ratches and joints of stainless steel instruments. For satin/matt finish instruments, we use glass heads to achieve uniformity. All instruments are being polished under rigid quality control specifications.
9- PASSIVATION: This method actually provides the instruments with its corrosion resistance properties. Passivation, which follows the final polishing step, is a chemical bath, which creates an oxidized layer on the surface of instruments. We are now equipped with most modern process.
10- ULTRASONIC CLEANING: We are full equipped with most modern ultrasonic cleaning plants imported from “Branson Cleaning Equipment Co. USA”, and all instruments are being cleaned properly utilizing various chemicals such as, Tri-Chloroethlyine etc.
11- INSPECTION & STAMPING: We inspect all instruments under rigid Q/C. specifications and give the assurance to our relative clients that all instruments shall be free from all defects such as, burrs, sharp edges, cracks, pitting, scratches, grease / excessive oil and foreign matters etc. We also guarantee for its workmanship. For stamping, we use both process i.e. die sunk and electrolytic marking and are being marked under customer’s specifications.
12- PACKING & LABELING: We pack all instruments under strictly Q/C. specifications as per customer’s demand. Normally, we pack individually in poly bag and further 12 pieces in one box mentioning outside with Part Number, Description and Lot Number. All instruments are packed in polybags with adequate desiccant in each poly bag to absorb moisture. Mostly, we are packaging and labeling as per customer demand.