Increase in Intraoperative Intraocular Pressure in the Prone Position.

Introduction: This study aimed to measure the intraocular pressure (IOP) of patients undergoing open surgery in the supine position (control group) and spine surgery in the prone position (spine group) to clarify IOP range and change by posture, determine the risk factors for increased IOP in the prone position, and reduce visual complications after surgery in the prone position. Methods: A prospective cohort study was conducted in healthy adults (34-83 years of age) with an American Society of Anesthesiologists classification I/II. The spine group was examined for IOP, anterior chamber angle (ACA), and fundus findings the day prior to surgery. On the day of surgery, IOP measurements were taken at fixed time points: immediately after intubation; at 0.5, 1, and 2 h after intubation; at suture closure; and at the end of surgery in the control group. In the spine group, they were taken immediately after intubation; at 0.5, 1, and 2 h after prone position; at suture closure; and immediately and 5 min after returning to the supine position. The risk factors for increased IOP in the prone position were examined. Results: The control group showed no significant changes in IOP within the normal range (<20 mmHg) during surgery. In the spine group, IOP was higher at each time point than immediately after intubation. IOP increased sharply above the normal range within 1 h after changing from the supine to the prone position and continued to gradually increase until suture closure. IOP decreased 5 min after the patient returned to the supine position. ACA, body mass index, blood loss, time in the prone position, and operative time were not risk factors for increased IOP in the prone position. Conclusions: Patients were constantly exposed to above-normal IOP during prone spinal surgery. However, neither group reported visual impairment. No risk factors were identified for increased IOP in the prone position.

Characteristics of weak base-induced vacuoles formed around individual acidic organelles.

We have previously found that the weak base 4-aminopyridine induces Brownian motion of acidic organelles around which vacuoles are formed, causing organelle traffic disorder in neurons. Our present study investigated the characteristics of vacuoles induced by weak bases (NH(4)Cl, aminopyridines, and chloroquine) using mouse cells. Individual vacuoles included acidic organelles identified by fluorescent protein expression. Mitochondria and actin filaments were extruded outside the vacuoles, composing the vacuole rim. Staining with amine-reactive fluorescence showed no protein/amino acid content in vacuoles. Thus, serous vacuolar contents are probably partitioned by viscous cytosol, other organelles, and cytoskeletons, but not membrane. The weak base (chloroquine) was immunochemically detected in intravacuolar organelles, but not in vacuoles. Early vacuolization was reversible, but long-term vacuolization caused cell death. The vacuolization and cell death were blocked by the vacuolar H(+)-ATPase inhibitor and Cl--free medium. Staining with LysoTracker or LysoSensor indicated that intravacuolar organelles were strongly acidic and vacuoles were slightly acidic. This suggests that vacuolization is caused by accumulation of weak base and H(+) in acidic organelles, driven by vacuolar H(+)-ATPase associated with Cl(-) entering, and probably by subsequent extrusion of H(+) and water from organelles to the surrounding cytoplasm.

Vesicle disruption, plasma membrane bleb formation, and acute cell death caused by illumination with blue light in acridine orange-loaded malignant melanoma cells.

Acridine orange (AO), a weakly basic fluorescent dye, is permeable to plasma and vesicle membranes and preferentially remains in intracellular acidic regions. Using fluorescence microscopy, we observed dynamic changes in AO-loaded cultured malignant melanoma cells during illumination with blue light. Immediately after the start of the illumination, the successive disruption of vesicles was observed as a flash of fluorescence, and shortly after that, blebs were formed on the plasma membrane. These cells died within 5 min. Vesicle disruption was completely inhibited when cells were treated with the vacuolar H(+)-ATPase inhibitor bafilomycin A1 followed by loading with AO, but not when bafilomycin A1 was treated after AO loading. Thus, the filling of AO in the vesicle, which is driven by vacuolar H(+)-ATPase, is initially required for vesicle disruption. In contrast, bafilomycin A1 did not prevent plasma membrane blebbing, indicating that the blebs are formed independently of the vesicle disruption. Acute cell death was inhibited by treatment with bafilomycin A1 before but not after AO loading. Thus, AO- and blue light-induced acute cell death is associated with vesicle disruption rather than bleb formation. Both the vesicle disruption and the formation of plasma membrane blebs were inhibited by removal of oxygen from the cell environment and by singlet oxygen scavengers, sodium azide, ascorbic acid, and L-histidine, but not inhibited by the hydroxyl radical scavenger dimethyl thiourea. Acute cell death was also prevented by singlet oxygen scavengers but not by dimethyl thiourea. Thus, these phenomena are likely caused at least in part by the generation of singlet oxygen. The photosensitive features of plasma and vesicle membranes observed in the present study may be based on the use of the photodynamic effect, such as cancer therapy.

Nitric oxide generated by iNOS reduces deformability of Lewis lung carcinoma cells.

Previous studies have indicated that NO plays a crucial role in the metastasis of tumor cells and that tumor cells produce nitric oxide (NO) via inducible nitric oxide synthase (iNOS). Since the deformability of tumor cells is an important factor governing their metastatic potential, in this study we investigated the regulation of tumor cell deformability by NO. Lewis lung tumor cells (3LL cells) were also incubated with a cytokine mixture (IL-1 beta, IFN gamma, and TNF alpha). The nitrite/nitrate content of the supernatant was then measured by the Griess method, and iNOS expression was evaluated by RT-PCR in vitro. Nitrite/nitrate was produced in response to administration of the cytokine mixture, and iNOS mRNA was expressed in the cytokine-treated cells. The deformability of the 3LL cells was evaluated by measuring the peak pressure generated during their passage through a microfilter at a constant flow rate. Both the cytokine mixture and NO donor (NOC 18) significantly increased the filtration pressure, and the staining of the cells with rhodamine-phalloidin revealed assembly of F-actin in the cell membrane. In conclusion, NO plays a role in the decreased deformability of tumor cells, suggesting that NO is one of the factors that regulates metastasis.

Expression of neurotrophins and their receptors in peripheral lung cells of mice.

Neurotrophins play an essential role in nerve systems. Recent reports indicated that neurotrophins [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5)] have numerous effects on non-neural cells, especially on immune cells. However, whether lung cells express neurotrophins and/or their receptors (TrkA for NGF, TrkB for BDNF and NT-4/5, and TrkC for NT-3) has never been systematically investigated. We investigated constitutive expression of neurotrophin family and their Trk receptor family in alveolar macrophages and other peripheral lung cells of mice. New findings were: (1) RT-PCR for neurotrophins and their receptors detected NT-3 and NT-4/5 in alveolar macrophages, BDNF, NT-4/5, trkA, the truncated form of trkB, and trkC in lung homogenate, but no trks in alveolar macrophages, (2) immunohistochemistry for neurotrophin receptors detected TrkA in capillary cells, the truncated form of TrkB, and TrkC in interstitial macrophages, (3) immunoelectron microscopy for TrkC revealed expression of TrkC on the surface of interstitial macrophages, and (4) in situ hybridization for neurotrophins detected BDNF in interstitial macrophages and alveolar type I cells, NT-3 in alveolar macrophages, and NT-4/5 in alveolar and interstitial macrophages. These findings indicate that a previously unknown signal trafficking occurs through neurotrophins in peripheral lung.