A route toward fabrication of 3D printed bone scaffolds based on poly(vinyl alcohol)-chitosan/bioactive glass by sol-gel chemistry

Among different methods for the fabrication of bone scaffolds, 3D printing has created great advances in tissue engineering and regenerative medicine owing to its ability to make objects mimicking native tissues. Thanks to its abundant availability, structural features, and favorable biological properties, chitosan (CS) hydrogel was selected to be used for preparation of the bone scaffolds. However, the 3D printing of CS-based hydrogels is still under early exploration. Knowing the fact that natural polymers are not so competent at holding large amounts of water, poly(vinyl alcohol) as the second polymer was employed. The novelty of the present research lies in the concept of employing sol-gel chemistry in order to attain proper viscosity and rheological behavior to give self-standing filaments of the polymer blends. Employing sol-gel reaction in the preparation of the hybrid hydrogels had the advantage of endowing shape fidelity to the polymer blend without any solidifying in the needle. The obtained organic-inorganic hybrids were directly printed and subsequently cross-linked. The best performance in terms of mechanical strength, cell viability, and bio-mineralization was observed for the 50:50 ratio. The in vitro cell culture and the bioactivity results showed that the printed scaffolds with this method have great potential in bone tissue engineering. Further, this method could be expandable to print other hydrogels with diverse applications such as implantable devices, soft robotics, etc.

A case of fatal strongyloidiasis in a patient with chronic lymphocytic leukemia and molecular characterization of the isolate

Strongyloides stercoralis is a human intestinal parasite which may lead to complicated strongyloidiasis in immunocompromised. Here, a case of complicated strongyloidiasis in a patient with chronic lymphocytic leukemia is reported. Presence of numerous S. stercoralis larvae in feces and sputum confirmed the diagnosis of hyperinfection syndrome in this patient. Following recovery of filariform larvae from agar plate culture of the stool, the isolate was characterized for the ITS1 region of ribosomal DNA gene by nested-PCR and sequencing. Albendazole therapy did not have cure effects; and just at the beginning of taking ivermectin, the patient died. The most important clue to prevent such fatal consequences is early diagnosis and proper treatment.

Transverse keratotomy followed by LASIK for the treatment of naturally occurring astigmatism

PURPOSE

To evaluate the efficacy of transverse keratotomy followed by LASIK for patients with high amounts of naturally occurring astigmatism.

METHODS

Thirteen eyes with naturally occurring astigmatism ranging from -3.75 to -6.50 diopters (D) underwent sequential transverse keratotomy (60 degrees at 6 mm) and LASIK procedures. The effect of these two procedures on the amount of astigmatism was studied.

RESULTS

Transverse keratotomy led to a 46% reduction in refractive cylinder from -5.50 +/- 0.80 D to -3.00 +/- 1.00 D. After LASIK, the initial refractive astigmatism was reduced by 90% to -0.50 +/- 0.50 D with a minimum follow-up of 6 months.

CONCLUSIONS

The combined technique of transverse keratotomy followed by LASIK is an effective and accurate way to treat high amounts of naturally occurring astigmatism, allowing the size of the optical zone of the excimer laser ablation to be maximized.