1,721,171 research outputs found
Etiopatogenesi, gradazione e frequenza dell’artropatia acromio-clavicolare.
No full textDell’artrosi AC sappiamo che ha inizio già a partire dalla seconda decade di vita; che è presente in oltre il 50% dei pazienti ultrasessantenni e che in 2/5 degli anziani l'AC è dolente alla pressione. E noto, inoltre, che l'artrosi è più frequente nei lavoratori manuali e ciò depone per un'origine meccanica della patologia. Un recente nostro studio ha anche rilevato una percentuale elevata di artrosi AC in soggetti con articolazione coraco-clavicolare. Nonostante il riscontro frequente, non esiste una classificazione radiografica universalmente riconosciuta che permetta una stadiazione dell'artrosi AC. Pertanto si ricorre a classificazioni modificate impiegate per l'artrosi gleno-omerale. Noi abbiamo condotto uno studio sull'artrosi AC in soggetti asintomatici ed analizzato la correlazione tra artrosi, sesso, morfologia dell'acromion ed ampiezza dello spazio acromio-omerale (AO). Lo studio è stato condotto su 222 volontari asintomatici. L'artropatia è stata considerata di grado lieve moderato e marcato secondo la classificazione di Samilson e Prieto modificata. Lo spazio AO è stato misurato sui radiogrammi nella proiezione vera AP con il metodo di Petersson. Gli acromion sono stati classificati secondo il metodo di Edelson. La significatività statistica è stata valutata mediante il test del y} ed il t-Test (livello di significatività& p 0.05) e tra le femmine artrosiche (8.0 mm) e non artrosiche (8.6 mm) (p >0.05). Gli acromion di forma squadrata (con faccetta articolare per l'articolazione AC posta all'apice dell'acromion) sono stati osservati in proporzione più elevata nei soggetti con artrosi (57%) che in quelli senza (48%) (p <0.05). CONCLUSiONi. La prevalenza dell'artrosi AC nei soggetti asintomatici & del 28.8% ed 6 superiore nei maschi. L'età media dei maschi artrosici 6 inferiore a quella delle femmine. Tali dati suggeriscono che l'artrosi può essere correlata al maggiore impegno funzionale della spalla dei maschi. La percentuale di artrosi asintomatica di grado marcato e di poco superiore all’ 1%. L ampiezza dello spazio AO non influenza la condizione dell'articolazione AC. La disposizione spaziale dell’articolazione AC può influire sulla genesi dell'artrosi. Infatti, la prevalenza degli acromion di tipo squadrato nei soggetti artrosici è risultata superiore a quella rilevata nei non artrosici
Geometrical, Conformational, and Topological Restraints in Nucleosome Compaction along Chromatin Fibers
No full textCompaction of nucleosomes in chromatin is directed by their positioning along DNA. The statistical analysis of the nucleosome repeat length in chromatin fibers reveals the presence of a ten-fold periodicity suggesting the existence of orientation constraints of the nucleosome units that provide the geometrical conditions of helical conformations. We investigated the architectures of the chromatin fiber by integrating the experimental results with geometrical, conformational and topological restraints, under the hypothesis of the minimum distortion of the nucleosome and linker DNA structures. The periodical repeats of nucleosomes can be investigated assuming the principle of conformational equivalence of the repeating units. The problem of selecting the compact architectures of the chromatin fiber for different linker lengths can be factorized in one in which only orientational parameters are taken into account and the other in which the lengths of DNA linkers are considered. The best packing of nucleosomes requires the uniformity of orientational parameters and “quasi-conformational equivalence” of the repeating units, even though linker lengths are not strictly equal. We showed that the path of the linkers in compact nucleosome packing is severely constrained by steric hindrances and topological conditions and that the excluded volume at linker crossing and the torsional energy limit the possible close packing of the nucleosomes in the chromatin fiber. In particular, the torsional energy of the chromatin fiber appears crucial in determining the kind of nucleosome packing for short nucleosome repeat lengths as in telomeres and yeast chromatin
Results of surgery afetr failed attempt at repair of irreparable rotator cuff tears
No full textAims
Numerous studies have analyzed the outcomes of surgery in massive cuff tears, but very little
is known on the results of open surgery aimed at repairing a rupture which, at surgery, is
found to be truly irreparable.
Methods
Twelve patients who had surgery to repair a rotator cuff tear which could not be repaired
because the residual tendon tissue was of poor quality or insufficient or both, were followed
for a mean of 33 months. At surgery, the deltoid was detached from the acromion for 4 to 6
cm and an acromioplasty was done. Preoperatively, all patients except for one, had mild to
severe pain and the mean active forward flexion, abduction and external rotation were 75°,
61° and 22°, respectively.
Results
After surgery, of the 11 patients who had shoulder pain preoperatively, 10 reported partial
relief of pain and one was painfree. However, shoulder function deteriorated in 11 patients
and remained unchanged in one who had a pseudoparalytic shoulder before and after surgery.
The mean postoperative values of forward flexion, abduction and external rotation were 49°,
43° and 16°, respectively. Only one patient was satisfied with the result of surgery because of
pain relief. Two patients had repeat surgery (total shoulder replacement or latissimus dorsi
transfer) 6 and 4 months after the index surgery because of an unsatisfactory functional
result.
Conclusions
Attempts at open repair of an irreparable cuff tear should be avoided because functional
results generally are poor. When there is a risk that an irreparable tear will be found, no open
surgery should be done or alternative procedures should be planned before surgery
Peptides with regular enantiomeric sequences as self-assembling nanotubes for nanotechnology.
No full textOrganic trans-annular assemblies constitute an expanding class of structures with promising applications
for the design of nanotechnological devices. Among the strategies developed for the engineering
of organic nanotubes, those characterized by regular alternating enantiomeric amino acid
sequences have been proven particularly useful. In fact, cyclic peptides with an even number of
regularly alternating D- and L-amino acids have the tendency to adopt local -conformation that
are capable of forming trans-annular self-assembling architectures, hydrogen bond directed. The
formation of such structures is the result of the conformational equivalence of the monomer units,
a general principle that associates stereo-chemical to chemical equivalence in a polymer chain.
For configurationally alternating sequences the conformational equivalence produces cyclic structures,
where a monomer unit is related to the adjacent along the chain by a roto-reflection axis,
Sn. A slight relaxation of the conformational equivalence can formally transform a cyclic structure
into a conformationally quasi-equivalent helical structures characterized by the presence of polar
inner channels, which allow the transient binding for an activated flow of specific ions. To prove our
early predictions, we synthesized different alternating polypeptide and the corresponding linear and
cyclic oligopeptides and investigated their conformations by NMR and CD spectroscopy as well as
the formation of self-assembling structures by increasing the concentration in solution. Moreover,
their predicted ability to behave as an ion-channel across bilayer membranes are investigated and
experimental evidence of single molecule conducting events are reported. Finally, the possibility
is suggested to obtain self-assembled trans-annular structures by chemically bridging the amino
acid side chains stabilized using different strategies. A complex construct with good perspective for
nano-technological applications is proposed in which cyclic DL-lysine side chains are bridged by
the formation of pyridoxalaldimmine metal chelates
Inquinamento atmosferico, mobilità e salute pubblica in Italia
No full textlo scritto intende evidenziare la multifattorialità legata all'inquinamento atmosferico, tra aumento della mobilità ed esigenza di salut
"DNA adsorption on inorganic surfaces and nanostructure growth".
No full textThe preparation of DNA-based nanostructures is usually accomplished in solution, by the controlled-temperature assembly of a number of oligonucleotides into complex, often multi-modular structures. Several techniques are then used to lay the nanostructures on solid surfaces, either to make them amenable to further studies with surface techniques (such as the atomic force microscope) or to integrate them on microfabricated devices.
The adsorption of nucleic acids on inorganic surfaces can take place with orientational preference as a function of the DNA base sequence. Evidence was obtained of the capability of the mica surface of recognising the two faces of a strongly curved DNA fragment.[1] The differential free energy involved in that recognition mechanism was estimated, and the modulation, by the same recognition process, of the conformational space accessible to a DNA molecule upon its deposition on mica was evidenced. On the basis of these data a tentative model based on sequence-dependent unbalances of the charge distribution along the chain is proposed. This model suggests that the crystal surface can recognise such unbalances of charge, and that the recognition process does not necessarily require curved tracts: it could act also in straights DNAs.[2]
A fine control of surface adsorption properties could also prove beneficial for the control and tailoring of DNA-based nanostructure growth, as this can be accomplished directly on surfaces. We have evidence that growing DNA nanostructures based on the stable Holliday junction could take place through only some of the possible pathways when performed on the surface, if compared to solution growth. We collected experimental data on a system based on the DNA parallelogram motif introduced by Prof. Seeman [3] where the assembly could be made more efficient to the point that kinetically-trapped unwanted structures could be avoided by forcing the growth to take place while all the components are adsorbed on a surface. As a fringe benefit, the reduction of dimensionality inherent in the surface adsorption enables the assembly to take place at strongly reduced oligonucleotide concentrations if compared to solution assembly.
[1] Sampaolese, B., Bergia, A., Scipioni, A., Zuccheri, G., Savino, M., Samorì, B., and De Santis, P. Recognition of the DNA sequence by an inorganic crystal surface. Proc Natl Acad Sci U S A, 2002. 99(21): p. 13566-70.
[2] Scipioni, A., Pisano, S., Bergia, A., Savino M., Samorì, B., and De Santis, P. Sequence-dependent DNA recognition by an inorganic crystal surface in the nanoscale (in pubbl.)
[3] Mao, C., W. Sun, and N.C. Seeman, Designed Two-Dimensional DNA Holliday Junction Arrays Visualized by Atomic Force Microscopy. J. Am. Chem. Soc., 1999. 121: p. 5437-544'
RELATIONSHIP BETWEEN OS ACROMIALE AND ACROMIOCLAVICOLAR JOINT ANATOMIC POSITION
Full text linkMost of the orthopaedic literature on os acromiale is focused on the clinical
implications, such as impingement and rotator cuff tears; although os acromiale
is present in 8% of subjects, scarce information is reported on the causes that
may predispose patients to it. Our aim is to investigate whether the origin of os
acromiale is related to the position of the acromioclavicular (AC) joint. The
acromions of 211 volunteers (control group) and 33 subjects without or with os
acromiale were radiographically (axillary view) classified by the Edelson and
Taitz method. The method distinguishes the acromion into three types on the basis
of the distance between the anterior aspect of the acromion and the AC joint. Of
33 subjects with os acromiale, 11 were without pain. We have compared the
frequency of the three types of acromion observed in the two investigated
cohorts. Half of the acromions of the control group (52.1%) had the articular
facet of the AC joint on the acromion tip, whereas in 45.4% the facet tip was
located distally. On the other hand, of 33 subjects with os acromiale, 18.1% and
81.1%, respectively, had the AC joint lying on or distal to the acromion tip. Our
data suggest that the greater the distance of the AC joint from the anterior edge
of the acromion, the higher the likelihood of an os acromiale
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