Mass spectrometry study of a transferrin-based protein drug reveals the key role of protein aggregation for successful oral delivery

A recently designed human growth hormone/transferrin fusion protein (GHT) remains one of the very few examples of a protein capable of eliciting measurable therapeutic response after oral administration. To better understand the underlying factors that resulted in this rare success of nonparenteral protein drug delivery, we analyzed proteolytic stability and receptor binding properties of this protein, the key factors in overcoming the primary barriers to successful oral delivery. Analysis of GHT by a combination of size exclusion chromatography and mass spectrometry revealed that a significant protein population exists in an oligomeric (GHTx) state in addition to the anticipated monomer (GHT1). These states of GHT were evaluated for their survivability in stomach-like conditions, as well as their ability to bind transferrin receptor (TfR). Our results reveal an exceptional stability of GHTx, as well as the preserved ability to bind TfR, a critical first step in crossing the epithelial-intestinal barrier through receptor-mediated transcytosis.     

Minilaparoscopy-assisted transrectal low anterior resection (LAR): a preliminary study

Background

Natural orifice translumenal endoscopic surgery (NOTES) represents the evolution of surgery towards less invasive procedures. The feasibility of NOTES transrectal approach has increased its clinical applicability. This report describes a first series of minilaparoscopy-assisted transrectal low anterior resection with double purse-string end-to-end circular stapler anastomoses.

Methods

Between March and April 2012 three selected patients underwent transrectal minilaparoscopy-assisted natural orifice surgery total mesorectal excision for rectal cancer. All the oncologic principles of open/laparoscopic low anterior resection for rectal cancer were strictly fulfilled. Two patients underwent neoadjuvant treatment. Laparoscopic visualization and assistance was provided through one 10-mm umbilical port and two ports, one of which was used as stoma site (5 mm) and the other as a drain site (2 mm needle port). The specimen was transected transanally followed by the confection of double purse-string lateral/end-to-end anastomoses. There were no intraoperative complications.

Results

Mean operative time was 143 min. Oral intake was initiated on the second postoperative day. Patients were discharged home by day 5. The pathology unit confirmed that distal and circumferential margins were free of tumor invasion, and quality of mesorectum resection was reported satisfactory. One patient had to be readmitted because of severe dehydration due to increased ileostomy output. The patient was discharged at the third day after the readmission without renal failure.

Conclusions

In this preliminary report, transrectal minilaparoscopy-assisted low anterior resection was feasible and safe. Lateral/end-to-end anastomoses can be considered an interesting alternative to the double-stapling technique. However, it is necessary to further study and develop these procedures, along with careful patient selection, before transrectal low anterior resection may be considered for routine clinical use.