An unusual case of foreskin phimosis after radiotherapy for rectal carcinoma.

Phimosis of the foreskin after radiotherapy for rectal carcinoma is extremely rare and has previously been described only once (2006) in the English-language literature. Combination chemo/radiotherapy is currently the treatment of choice and widely used in the management of various pelvic malignancies. In this report, we describe a rare complication on male genitalia following the radiotherapy for lower rectal cancers. Few days following the completion of radiotherapy, patient developed phimosis of the foreskin, which was successfully treated medically without the need for circumcision. Radiotherapy can bring a great risk of injury to anorectum and its adjacent structures. Risk of phimosis should be considered under the current radiation guidelines and we support the concept of using penile shielding for all radiotherapy procedures in colorectal carcinoma patients.

Non-surgical treatment of anterior open bite and its assessment using the Dawjee analysis: a case report.

Anterior open bite (AOB) is a dentofacial problem occurring more commonly in race groups of African origin. Although multi-factorial, the aetiology exerts its influence in tandem with craniofacial development. Diagnosis is confirmed by a cephalometric assessment and points either to a skeletal origin, a dental source, or both. Depending on the time of diagnosis and severity of the condition, treatment can vary from interceptive procedures, orthodontics only, or a combination of orthodontic treatment and orthognathic surgery. A case study is presented of an adult female with AOB who was treated nonsurgically. The diagnosis, treatment technique and outcome are described, as well as a pre- and post-treatment evaluation of the cephalograms using the Dawjee analysis. Comparison of pre- and post-treatment cephalometric values show a definite dentofacial improvement, and identifies specific morphologic areas that have changed as a result of treatment. Transformations in anteroposterior maxillary and mandibular positions and orientation are readily detectable, as well as a repositioning of the alveolar processes. While pre and post treatment cephalometric values presented for this patient compare well, these values are case specific and cannot be implemented widely unless the analysis is applied to a larger and more representative population sample and standardised measurements have been established.

Giant vesicles as models to study the interactions between membranes and proteins.

The interaction between polypeptides and membranes is a fundamental aspect of cell biochemistry. Liposomes have been used in this context as in vitro systems to study such interactions. We present here the case of giant vesicles (GVs), which, due to their size (radius larger than 10 microns), mimic more closely the situation observed in cell membranes and furthermore permit to study protein-membrane interactions by direct optical monitoring. It is shown that GVs formed from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine by electroformation are permeable to certain low molecular weight molecules such as the nucleic acid dye YO-PRO-1 and fluorescein diphosphate whereas conventional liposomes (large or small unilamellar liposomes) are not. In addition, it is shown that non-membrane proteins, such as DNases or RNases, added to the selected GVs from the outside, are able to convert their substrate, which is strictly localized on the internal side of the membrane. This effect is only seen in GVs (also when they are removed from the original electroformation environment) and is absent in conventional liposomes. The fact that these effects are only present in GVs obtained by electroformation and not in conventional small liposomes is taken as an indication that certain physico-chemical properties of the bilayer are affected by the membrane curvature, although the mechanism underlying such differences could not be established as yet.

Protein expression in liposomes.

Compartmentalization is one of the key steps in the evolution of cellular structures and, so far, only few attempts have been made to model this kind of "compartmentalized chemistry" using liposomes. The present work shows that even such complex reactions as the ribosomal synthesis of polypeptides can be carried out in liposomes. A method is described for incorporating into 1-palmitoyl-2-oleoyl-sn-3-phosphocholine (POPC) liposomes the ribosomal complex together with the other components necessary for protein expression. Synthesis of poly(Phe) in the liposomes is monitored by trichloroacetic acid of the (14)C-labelled products. Control experiments carried out in the absence of one of the ribosomal subunits show by contrast no significant polypeptide expression. This methodology opens up the possibility of using liposomes as minimal cell bioreactors with growing degree of synthetic complexity, which may be relevant for the field of origin of life as well as for biotechnological applications.

Entrapment of nucleic acids in liposomes.

The entrapment efficiency of three main methods used in the literature for the encapsulation of nucleic acids in liposomes were studied using 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes. In particular the reverse phase method, the dehydration/rehydration method, and the freeze/thawing method were compared to each other under standardised conditions, i.e. using in every case the same concentration of guest molecules (DNA, tRNA and ATP as low molecular weight analogue) and equally extruded liposomes. The percentage of entrapment strictly referred to the material localized inside the liposomes, i.e. particular care was devoted to ruling out the contribution of the nucleic acid material bound to the outer surface of the liposomes: this was eliminated by extensive enzymatic digestion prior to column chromatography. Depending on the conditions used, the percentage of the entrapped material varied between 10 and 54% of the initial amount. Further, the encapsulation efficiency was markedly affected by the salt concentration, by the size of liposomes, but to a lower degree by the molecular weight of the guest molecules. In general, we observed that the freeze/thawing encapsulation procedure was the most efficient one. In a second part of the work the freeze/thawing method was applied to encapsulate DNA (369 bp and 3368 bp, respectively) using liposomes obtained from POPC mixed with 1-10% charged cosurfactant, i.e. phosphatidylserine (PS) or didodecyldimethylammonium bromide (DDAB), respectively. Whereas PS had no significant effect, the entrapment efficiency went up to 60% in POPC/DDAB (97.5:2.5) liposomes. The large entrapment efficiency of DNA permits spectroscopic investigations of the DNA encapsulated in the water pool of the liposomes. UV absorption and circular dichroism spectra were practically the same as in water, indicating no appreciable perturbation of the electronic transitions or of the conformation of the entrapped biopolymer. This was in contrast to the DNA bound externally to the POPC/DDAB liposomes which showed significant spectral changes with respect to DNA dissolved in water.