l-Serine-modified polyamidoamine dendrimer as a highly potent renal targeting drug carrier.

Effective delivery of drug carriers selectively to the kidney is challenging because of their uptake by the reticuloendothelial system in the liver and spleen, which limits effective treatment of kidney diseases and results in side effects. To address this issue, we synthesized l-serine (Ser)-modified polyamidoamine dendrimer (PAMAM) as a potent renal targeting drug carrier. Approximately 82% of the dose was accumulated in the kidney at 3 h after i.v. injection of 111In-labeled Ser-PAMAM in mice, while i.v. injection of 111In-labeled unmodified PAMAM, l-threonine modified PAMAM, and l-tyrosine modified PAMAM resulted in kidney accumulations of 28%, 35%, and 31%, respectively. Single-photon emission computed tomography/computed tomography (SPECT/CT) images also indicated that 111In-labeled Ser-PAMAM specifically accumulated in the kidneys. An intrakidney distribution study showed that fluorescein isothiocyanate-labeled Ser-PAMAM accumulated predominantly in renal proximal tubules. Results of a cellular uptake study of Ser-PAMAM in LLC-PK1 cells in the presence of inhibitors [genistein, 5-(N-ethyl-N-isopropyl)amiloride, and lysozyme] revealed that caveolae-mediated endocytosis, micropinocytosis, and megalin were associated with the renal accumulation of Ser-PAMAM. The efficient renal distribution and angiotensin-converting enzyme (ACE) inhibition effect of captopril (CAP), an ACE inhibitor, was observed after i.v. injection of the Ser-PAMAM-CAP conjugate. These findings indicate that Ser-PAMAM is a promising renal targeting drug carrier for the treatment of kidney diseases. Thus, the results of this study demonstrate efficient renal targeting of a drug carrier via Ser modification.

A case of refractory pneumothorax and contralateral atelectasis after thoracoscopic subtotal esophagectomy treated with independent lung ventilation.

BACKGROUND: Independent lung ventilation (ILV) allows separate positive end-expiratory pressures (PEEP) and inspiratory pressures for each lung. However, only a few articles have reported ILV management for lungs affected by different pathologies. CASE PRESENTATION: A 56-year-old man underwent video-assisted thoracic surgery for esophageal cancer. The right lung was injured during surgery, causing a bronchopleural fistula and necessitating chest drainage. On the third day in the intensive care unit, the patient's oxygenation worsened during pressure support with continuous positive airway pressure ventilation. ILV was initiated for right-sided severe pneumothorax and left-sided atelectasis and pneumonia. ILV was continued for 2 days, and the patient's trachea was successfully extubated the following day. CONCLUSION: Applying high-level PEEP to the one lung and minimizing the airway pressure on the other lung could be achieved using ILV, which might contribute to successful tracheal extubation.

S-nitrosylated l-serine-modified dendrimer as a kidney-targeting nitric oxide donor for prevention of renal ischaemia/reperfusion injury.

Nitric oxide (NO) deficiency is known to play a role in renal ischaemia/reperfusion injury; therefore, kidney-targeting NO donor is expected to prevent renal ischaemia/reperfusion injury. We therefore developed an S-nitrosylated L-serine-modified polyamidoamine dendrimer (SNO-Ser-PAMAM), in which multiple S-nitrosothiols (NO donors) were covalently bound to L-serine-modified dendrimer, as a kidney-targeting NO donor. In the pharmacokinetic study, approximately 76% of 111In-SNO-Ser-PAMAM accumulated in the kidney after intravenous injection in mice. Furthermore, single photon emission computed tomography/computed tomography (SPECT/CT) imaging study showed that 111In-SNO-Ser-PAMAM specifically accumulated in the renal cortex after intravenous injection. SNO-Ser-PAMAM gradually released NO over a day in plasma, indicating that SNO-Ser-PAMAM would show sustained release of NO in vivo. In a mouse model of renal ischaemia/reperfusion injury, increased plasma creatinine, a kidney damage marker, and histological changes were effectively inhibited by intravenous administration of SNO-Ser-PAMAM. These results indicate that SNO-Ser-PAMAM is a promising kidney-targeting NO donor for the efficient prevention of renal ischaemia/reperfusion injury.

l-Cysteine and l-Serine Modified Dendrimer with Multiple Reduced Thiols as a Kidney-Targeting Reactive Oxygen Species Scavenger to Prevent Renal Ischemia/Reperfusion Injury.

l-cysteine (Cys)- and l-serine (Ser)-modified, third-generation polyamidoamine (PAMAM) dendrimer with multiple reduced thiols (Ser-PAMAM-Cys) was synthesized as a kidney-targeting reactive oxygen species (ROS) scavenger to help prevent renal ischemia/reperfusion injury. Ser-PAMAM-Cys effectively scavenged 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and ROS (hydrogen peroxide and hydroxyl radical) in phosphate-buffered saline (PBS). In addition, ~64% of 111In-labeled Ser-PAMAM-Cys accumulated in mouse kidney 3 h after intravenous administration. An in vivo imaging system (IVIS) study indicated that near-infrared fluorescence dye (NIR)-labeled Ser-PAMAM-Cys specifically accumulated in the kidney. In a mouse renal ischemia/reperfusion injury model, increases in the kidney damage markers creatinine (Cre) and blood urea nitrogen (BUN) were significantly inhibited by intravenous Ser-PAMAM-Cys administration. In contrast, Cys injection had no statistically significant effect of preventing Cre or BUN elevation relative to the control. Ser-PAMAM-Cys also effectively downregulated the inflammatory factors NGAL, IL-18, ICAM-1, and VCAM-1 in the renal ischemia/reperfusion injury model. These results indicate that Ser-PAMAM-Cys is a promising kidney-targeting ROS scavenger which could prevent ischemia/reperfusion-induced renal failure.