Pulmonary surfactant transport in alveolar type II cells

Abstract:   Pulmonary surfactant (PS) is a mixture of several lipids (mainly phosphatidylcholine; PC) and four apoproteins (A, B, C and D). The classical hypothesis of PS transport suggests that PS is synthesized in the endoplasmic reticulum and transported to the lamellar body (LB) via the Golgi apparatus. However, recent studies have raised questions regarding this single route. This study examined, independently, the intracellular trafficking route of three different components of PS, that is, PC, SP-A and SP-B. Alveolar type II cells were isolated from Sprague–Dawley rats or Japanese white rabbits. The cells were cultured with either [³H]choline or [³⁵S]methionine/cysteine with or without brefeldin A, which disassembles the Golgi apparatus. LB was purified from disintegrated cells with sucrose density gradient centrifugation. [³H]PC was extracted from radiolabeled media, cells, and the LB fraction with Bligh–Dyer's method. [³⁵S]SP-A or [³⁵S]SP-B was immunoprecipitated from each sample with a specific antibody. [³H]PC was transported and stored to the LB via a Golgi-independent pathway. [³⁵S]SP-A was transported to the Golgi apparatus, underwent glycosylation, and was then constitutively secreted. The secreted [³⁵S]SP-A was re-uptaken into the LB. [³⁵S]SP-B was transported and stored to the LB via the Golgi-dependent pathway. These results indicate that, rather than a single route, surfactant components take different pathways to reside in the LB. These different pathways may reflect the different nature and role of each surfactant component such as surface tension-lowering activity and innate host defense.     

Preoperative Characteristics of Auditory Brainstem Response in Acoustic Neuroma with Useful Hearing: Importance as a Preliminary Investigation for Intraoperative Monitoring

We classified the results of preoperative auditory brainstem response (ABR) in 121 patients with useful hearing and considered the utility of preoperative ABR as a preliminary assessment for intraoperative monitoring. Wave V was confirmed in 113 patients and was not confirmed in 8 patients. Intraoperative ABR could not detect wave V in these 8 patients. The 8 patients without wave V were classified into two groups (flat and wave I only), and the reason why wave V could not be detected may have differed between the groups. Because high-frequency hearing was impaired in flat patients, an alternative to click stimulation may be more effective. Monitoring cochlear nerve action potential (CNAP) may be useful because CNAP could be detected in 4 of 5 wave I only patients. Useful hearing was preserved after surgery in 1 patient in the flat group and 2 patients in wave I only group. Among patients with wave V, the mean interaural latency difference of wave V was 0.88 ms in Class A (n = 57) and 1.26 ms in Class B (n = 56). Because the latency of wave V is already prolonged before surgery, to estimate delay in wave V latency during surgery probably underestimates cochlear nerve damage. Recording intraoperative ABR is indispensable to avoid cochlear nerve damage and to provide information for surgical decisions. Confirming the condition of ABR before surgery helps to solve certain problems, such as choosing to monitor the interaural latency difference of wave V, CNAP, or alternative sound-evoked ABR.     

MORPHOLOGICAL AND BIOCHEMICAL EVIDENCE FOR APOPTOSIS IN THE TERMINAL HYPERTROPHIC CHONDROCYTES OF THE GROWTH PLATE

The purpose of this study was to investigate the mechanism of cell death in chondrocytes of the growth plate. In the degenerative chondrocyte zone of the growth plate, apoptotic chondrocytes were defeated by the in situ nick end labelling method, by DNA analysis in agarose gel, and by electron microscopy. The results of the in situ nick end labelling method and the occurrence of a ladder pattern of DNA in agarose gel analysis indicated the activation of endogenous endonucleases, resulting in DNA fragmentation. Electron micrographs showed the early morphological changes associated with apoptosis. This report presents both morphological and biochemical evidence for apoptosis in the terminal hypertrophic chondrocytes of the growth plate. These data suggest that apoptosis of degenerative chondrocytes may play an important role in the control of normal and pathological endochondral ossification.     

Effects of cytokines on human basophil chemotaxis

Basophil chemotactic activity (BCA) of eight recombinant human (rh) cytokines was examined. Highly purified basophils were obtained by Percoll discontinuous gradients, followed by negative selection using flow cytometry. Then BCA was measured by means of modified Boyden chamber method. Both interleukin (IL)-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) had much more potent BCA than complement C5a, leukotriene B4 and platelet activating factor, well known as granulocyte chemotactic factors. Chemotaxis rather than chemokinesis was shown in chequerboard analysis of basophil migration induced by IL-3 and GM-CSF. Relatively high concentrations of IL-5 also induced basophil migration, although predominantly chemokinetic. IL-8 had apparent BCA, which was not so high as that of C5a. In contrast, IL-2, IL-4, interferon(IFN)-gamma and granulocyte colony-stimulating factor (G-CSF) had no significant BCA. These findings suggest that IL-3, IL-5, GM-CSF and, perhaps, IL-8 have an effect on basophil migration as well as modulation of basophil mediator release and may provide some insight into the basophil accumulation observed in late-phase allergic responses.     

Purification of human blood basophils using negative selection by flow cytometry

Basophils were purified from peripheral blood of normal donors using Percoll discontinuous gradients and negative selection by flow cytometry. The mean purity of basophils obtained was 84.7 +/- 4.1 (s.d.)% (range 77.3-90.0%, n = 13). The overall yield of these procedures was 16.0 +/- 2.6% (range 11.0-19.9%, n = 13), and cell viability of purified basophils exceeded 90%. Properties of highly purified basophils obtained by flow cytometry did not differ from those of partially enriched basophil preparations from Percoll discontinuous gradients in respect of: (i) intracellular histamine content; (ii) percentage of spontaneous histamine release in buffer; and (iii) percentage of histamine release triggered by ionophore A 23187 or anti-IgE. Moreover, purified basophils responded chemotactically to complement C5a in a dose-dependent manner. These findings suggest that our procedure for purification of human basophils does not affect the functions of basophils and may be useful for in vitro studies on the role of basophils in hypersensitivity reactions such as bronchial asthma.     

Catheter Ablation of Atrial Fibrillation in Patients With Valvular Heart Disease: Long‐Term Follow‐Up Results

AF Ablation in Patients With Valvular Heart Disease . Background: The purpose of this study is to evaluate the efficacy of atrial fibrillation (AF) ablation in patients with moderate valvular heart disease (VHD). Methods: In total, 534 consecutive patients who underwent AF ablation were enrolled. Patients with a history of valve surgery or other structural heart disease were excluded. Patients with clinically moderate VHD (group‐1, n = 45) were compared with those without VHD (control group‐2, n = 436). Ipsilateral pulmonary vein antrum isolation (PVAI) was performed with a double Lasso technique in all the patients. Left atrial (LA) linear ablation was undertaken in persistent AF patients, if AF was inducible after PVAI. Results: Patients in group‐1 were significantly older and had a larger LA. PVAI was successfully achieved in all the patients. Patients in group‐1 received LA linear ablation more frequently during the index procedure. After a median of 26 months from the index procedure, the freedom from AF was significantly lower in group‐1 than group‐2 off antiarrhythmic drugs (AADs) (47% vs 69%, P = 0.002). Although there were more number of total procedures in group‐1 than group‐2, the freedom from AF was lower at median 24 months after the last procedure (78% vs 87%, P = 0.038). There was no significant difference in the freedom from AF on AADs (91% vs 95%, P = 0.356) or complication rate between the 2 groups. Atrial tachycardia following the index procedure was observed more frequently in group‐1 (P = 0.001). Conclusion: The patients with VHD undergoing AF ablation are less likely to remain in sinus rhythm at long term without AADs than those without VHD. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1193‐1198, November 2010)     

Usefulness of Craniograms in Discriminating Coiled Intracranial Aneurysms Requiring Retreatment

While endovascular coil embolization has become one of the major therapeutic modalities for intracranial aneurysms, long-term imaging follow-up is required because of the higher rate of retreatment compared with surgical clipping. The purpose of this study was to show the usefulness of craniograms to discriminate coiled intracranial aneurysms that required retreatment. Under the study protocol approved by institutional review board, a retrospective review of the medical record was done regarding coil embolization for intracranial aneurysms performed between January 2014 and December 2018. Coil embolization performed as the initial treatment and followed up for more than 1 year without additional treatment, and those performed as retreatment after the initial coil embolization performed at our institution were recruited. Craniograms obtained just after the initial treatment were compared with those obtained just before the additional treatment in the retreated cases and compared with the latest ones in the non-recurrence cases. Correlation between the morphological changes in the coil mass on the craniograms and retreatments was evaluated. During the study period, 288 coil embolization procedures for intracranial aneurysms were performed. From these, 191 treatments that were followed up for more than 1 year without any additional treatments and 30 retreatments were included. Morphological change of the coil mass was observed in 4 of the 191 non-recurrence treatments and 26 of the 30 retreatments, which was significantly correlated with retreatments (p <0.001). Craniogram was a useful modality in following up the coiled intracranial aneurysms to detect those required retreatments.