Relationship between Swallowing Pressure and Saliva Residue on Endoscopic Evaluation in Pharyngeal Dysphagia.

OBJECTIVE: In pharyngeal dysphagia, poor pharyngeal contraction and upper esophageal sphincter (UES) dysfunction result in post-swallow saliva residue (SR). This study aimed to clarify the relationship between swallowing pressure and SR in the valleculae and piriform sinuses on flexible endoscopic evaluation of swallowing (FEES). METHODS: Pharyngeal dysphagia patients with Wallenberg syndrome were included. Amounts of post-swallow SR in the valleculae and piriform sinuses were classified into four grades using SR scores based on FEES. The Hyodo score was also calculated to evaluate swallowing function. High-resolution manometric data in the nasopharyngeal, oropharyngeal, hypopharyngeal, oro-hypopharyngeal, and UES zones on swallowing were obtained for comparison with SR and Hyodo scores. RESULTS: Of the 31 recruited, data from 26 patients who successfully underwent FEES and manometry were analyzed. Vallecular SR scores were strongly negatively correlated with a maximum pressure of the oropharynx (r = -0.52, p = 0.006), distal contractile integrals (DCI) of the oropharynx (r = -0.52, p = 0.007), and DCI of the oro-hypopharynx (r = -0.55, p = 0.004). Hyodo scores for parameters 1 and 4 (corresponding to salivary pooling and pharyngeal clearance, respectively) were strongly negatively correlated with a maximum hypopharyngeal pressure (r = -0.57, p = 0.002) and strongly positively correlated with peristaltic velocity (r = 0.53, p = 0.007), respectively. SR scores and Hyodo scores related to SR were not correlated with pressure data of the UES. CONCLUSION: Manometric analysis of our SR scoring method using FEES revealed that a higher amount of SR in the valleculae, but not in the piriform sinuses, is associated with weaker pharyngeal pressure in pharyngeal dysphagia, especially at the oropharyngeal level. LEVEL OF EVIDENCE: 4 Laryngoscope, 2024.

Twin vocal folds as a novel evolutionary adaptation for vocal communications in lemurs.

Primates have varied vocal repertoires to communicate with conspecifics and sometimes other species. The larynx has a central role in vocal source generation, where a pair of vocal folds vibrates to modify the air flow. Here, we show that Madagascan lemurs have a unique additional pair of folds in the vestibular region, parallel to the vocal folds. The additional fold has a rigid body of a vocal muscle branch and it is covered by a stratified squamous epithelium, equal to those of the vocal fold. Such anatomical features support the hypothesis that it also vibrates in a manner like the vibrations that occur in the vocal folds. To examine the acoustic function of the two pairs of folds, we made a silicone compound model to demonstrate that they can simultaneously vibrate to lower the fundamental frequency and increase vocal efficiency. Similar acoustic effects are achieved using different features of the larynx for the other primates, e.g., by vibrating multiple sets of ventricular folds in several species and further by an evolutionary modification of enlarged larynx in howler monkeys. Our multidisciplinary approaches found that these functions were acquired through a unique evolutionary adaptation of the twin vocal folds in Madagascan lemurs.

Pathogenesis of Reinke's Edema of the Vocal Fold.

OBJECTIVES: The most frequent etiologic factor of Reinke's edema (RE) is considered to be smoking. However, the mechanism for the onset and development of the disease remains unclear. Hypoxia-inducible factor-1α (HIF-1α) is an oxygen-dependent transcriptional activator which plays crucial roles in angiogenesis in hypoxic microenvironments. HIF-1α induces the expression of vascular endothelial growth factor (VEGF) which involves angiogenesis and enhances vascular permeability. This study investigated the roles of HIF-1α in the pathogenesis of RE. METHODS: Surgical specimens of RE from patients who underwent endolaryngeal microsurgery were used. Normal vocal folds were used as a control group. Expression of HIF-1α and VEGF was analyzed by immunohistochemistry. Three-dimensional fine structures of the vessels in RE were investigated using correlative light and electron microscopy (CLEM) technique. RESULTS: HIF-1α and VEGF were broadly expressed in the stromal, inflammatory, and endothelial cells in the lamina propria of the vocal fold of RE. The expression of HIF-1α and VEGF of RE were significantly higher than in the lamina propria of the normal vocal fold mucosa. CLEM showed vascularization and telangiectasia and there were many dilated capillaries with thin endothelium not covered with pericytes indicating the vessels were fragile. CONCLUSION: Transcription factor HIF-1α and induced VEGF likely play roles in the pathogenesis of RE. And increased vascular permeability with fragile vessels in angiogenesis is likely to be an etiology of RE. Transcription factor HIF-1α and induced VEGF are potential therapeutic targets for RE. LEVEL OF EVIDENCE: NA Laryngoscope, 134:1785-1791, 2024.

Glycolytic Metabolism of the Tissue Stem Cells in the Maculae Flavae of the Human Vocal Fold.

OBJECTIVES: Metabolic programs in the stem cells are essential for maintaining homeostasis and protecting against stem cell aging. There is growing evidence that the tissue stem cells reside in the anterior and posterior maculae flavae of the human vocal fold mucosa. Our previous studies observed that the glycolysis of the cell in the human maculae flavae seems to rely more on anaerobic glycolysis for energy supply in comparison with oxidative phosphorylation. However, previous studies showed only the metabolic enzymes of glycolysis and functional morphology of the mitochondria, therefore, it has not yet been determined whether anaerobic glycolysis actually took place. The purpose of this study is to investigate the glycolytic metabolites of the cells in the maculae flavae of the human vocal fold in vitro. METHODS: Four normal human vocal folds were used. After extraction of the anterior maculae flavae, cells in the maculae flavae were cultured and proliferated. Glucose transporter-1 was assessed using immunocytochemistry and metabolites of glycolysis (lactate and NADPH) were measured. RESULTS: The cells in the maculae flavae expressed glucose transporter-1 in the cytoplasm and the cell membranes. In addition, the cultured cells produced lactate (metabolites of anaerobic glycolysis) and NADPH (metabolites of the pentose phosphate pathway). CONCLUSIONS: The cells in the maculae flavae of the human vocal folds were found to undergo anaerobic glycolysis via the pentose phosphate pathway. This suggests that the cells in the maculae flavae of the human vocal fold have a metabolism that favors the maintenance of stemness and undifferentiated states.

Comparative Histoanatomy of the Epiglottis and Pre-epiglottic Space of the Chimpanzee Larynx.

OBJECTIVES: Understanding of the evolution of the larynx clarifies the physiology and functional histoanatomy of the present-day human organ. Comparative histoanatomy of the epiglottis and pre-epiglottic space of the chimpanzee larynx (a hominid, phyletic closest relative of humans) was investigated. METHODS: Two normal adult chimpanzee larynges obtained from natural deaths were investigated. The whole organ serial section technique was employed. RESULTS: The histoanatomical structures of the chimpanzees' epiglottis and pre-epiglottic space were considerably similar to those of human adults. The chimpanzees' epiglottic cartilage was relatively thin and composed of elastic cartilage. These histologic findings of epiglottis indicate that the chimpanzee's epiglottis is flexible and plays the role of retroflection. The chimpanzees' larynges had a pre-epiglottic space composed of adipose tissue and loose connective tissue. Epiglottic cartilage was connected to the thyroid cartilage anteroinferiorly with an intervening thyroepiglottic ligament and to the hyoid bone anteriorly with an intervening hyoepiglottic ligament. These histoanatomical structures of the epiglottis and pre-epiglottic space reflect the fact that chimpanzees have a descended larynx and acquire the pharyngeal space of the vocal tract. CONCLUSION: The results of this study are consistent with the hypothesis that, in the process of evolution, the histoanatomical structures of the epiglottis and pre-epiglottic space change and allow the larynx to descend and lengthen the pharyngeal space of the vocal tract which facilitates speech production in humans. Moreover, the distribution of the human pre-epiglottic space likely allows the epiglottis to more effectively play the role of retroflection during swallowing in order to prevent aspiration.

Additional effect of anthracycline in preoperative chemotherapy with a sequential anthracycline­containing regimen preceded by pertuzumab, trastuzumab and docetaxel combination therapy.

The proper use of anthracycline-containing regimens in combination with anti-HER2-targeted therapy in a neoadjuvant setting for patients with HER2-positive breast cancer has not been resolved. Regimens preceded by anthracyclines have become the standard of care, and although the order has no significant impact on HER2-negative breast cancer, it is inconclusive as to whether a taxane-first sequence would have a similar effect on HER2-positive breast cancer. The present study aimed to investigate the benefit of a taxane-first sequence and of adriamycin and cyclophosphamide (AC) in patients with non-clinical complete response (non-cCR) to pertuzumab, trastuzumab and docetaxel (PTD). The present single-center prospective observational study was performed to investigate PTD followed by AC, and aimed to clarify the cCR rate after PTD alone and the pathological clinical response (pCR) rate after subsequent AC in patients without cCR after PTD alone. A total 24 patients were analyzed; of these, 14 achieved pCR (pCR rate, 58.3%). While four of 14 patients (28.6%) in the intention-to-treat population achieved pCR, nine of 14 patients (64.3%) achieved pCR with AC but not cCR after PTD. The median tumor reduction rate after four cycles of PTD was 58.9% (range, 20.8-100%) in all 24 patients, whereas the reduction rate after PTD-AC was 76.9% (range, 31.1-100%). Cardiac serious adverse events occurred in three patients (12.5%). In conclusion, a high pCR rate was observed for the taxane-first sequence. Patients were highly responsive to PTD, but some cases achieved additional antitumor effects after AC, which resulted in pCR without cCR after PTD alone. Since cardiotoxicity remains a significant problem, a higher risk-benefit treatment strategy is required to aim for AC omission. Trial registration number: UMIN000046338, name of registry: UMIN-CTR, date of registration: December 10, 2021.

Vascularity in the macula flava of human vocal fold as a stem cell niche.

OBJECTIVES: There is growing evidence that the maculae flavae of the human vocal fold are a stem cell niche, which is a microenvironment nurturing tissue stem cells. This study investigated the microenvironment, especially vascularity, in the maculae flavae of the human vocal fold. METHODS: Three normal human adult, three normal newborn vocal folds obtained from autopsy cases and three surgical specimens of glottic carcinoma were investigated using light and electron microscopy. For scanning electron microscopy, a chemical digestion method (modified sodium hydroxide maceration method) was used to observe the inner 3-dimensional structure of the macula flava. RESULTS: Capillaries ran around the anterior and posterior maculae flavae in adults and newborns. However, there was no vascularity in the maculae flavae of the vocal fold. The inner 3-dimensional electron microscopic structure of the macula flava showed there were no blood vessels in the maculae flavae of the vocal fold. Glottic carcinoma (squamous cell carcinoma) surrounded and was in contact with the macula flava, however, the carcinoma did not invade the macula flava indicating there was no vascular supply into the macula flava from the surrounding tissue. CONCLUSIONS: There was no vascularity in the anterior and posterior maculae flavae in the human adult and newborn vocal folds. The present study is consistent with the hypothesis that the hypoxic microenvironment in the maculae flavae of the adult and newborn vocal fold as a stem cell niche is likely favorable to maintaining the stemness and undifferentiated states of the tissue stem cells in the stem cell system.

Distribution of Label-Retaining Cells and their Properties in the Newborn Vocal Fold Mucosa.

OBJECTIVES: There is growing evidence that the cells in the maculae flavae (MFe) are candidates for tissue stem cells of the vocal fold mucosa and the MFe are a stem cell niche. Distribution of label-retaining cells and their properties in the postnatal vocal fold mucosa were investigated. METHODS: Oral administration of bromodeoxyuridine (BrdU) was given to pregnant Sprague-Dawley rats and the label-retaining cells in the postnatal vocal fold mucosa were observed by immunohistochemistry. Immunoreactivity to antibodies directed to Ki-67 was studied to investigate the cell cycle. RESULTS: At day 1 after birth, BrdU positive cells were identified in the MFe (60.1 ± 1.7%), epithelium (58.7 ± 10.6%) and lamina propria (52.4 ± 7.8%) of the vocal fold mucosa. At day 56 after birth, the number of BrdU positive cells in the epithelium (4.8 ± 2.2%) and lamina propria (32.3 ± 16.5%) were significantly lower compared to day 1 after birth (P < 0.05). However, the number of BrdU positive cells remaining in the MFe was still high (56.2 ± 2.5%). The label-retaining cells were distributed throughout the MFe. Few Ki-67 positive cells were identified in the MFe indicating they were resting cells. CONCLUSIONS: The results of this study are consistent with the hypothesis that the cells in the postnatal MFe are candidates for tissue stem cells. At birth, these cells are already present in the MFe of the newborn vocal fold and they are likely ready to start the growth and development of the vocal fold mucosa.

Three-dimensional fine structures of the maculae flavae of the human vocal fold using correlative light and electron microscopy.

Objectives: To analyze various aspects of complex tissue, there is increasing demand to study each sample at different length scales in biology. Correlative light and electron microscopy (CLEM) is the latest technique to correlate two different types of information on the exact same histological area of interest: histology (from light microscopy) and ultrastructure (from electron microscopy). The three-dimensional fine structures of the maculae flavae (MFe) of the human vocal fold were investigated using CLEM. Methods: Five normal human adult vocal folds as specimens embedded in paraffin, sectioned, and mounted on glass slides with/without a chemical digestion method (modified sodium hydroxide maceration method) were investigated. Observations using CLEM were performed. Results: The fine structures of cells and extracellular matrices in the MFe and their peripheral regions were able to be observed on the exact same histological area of interest with the light microscope and field emission-scanning electron microscope. Cobblestone-like polygonal cells, vocal fold stellate cell-like cells, and fibroblast-like spindle cells were intermingled in the MFe of the human vocal fold. The extracellular matrices surrounding each three types of cell in the MFe differed, suggesting the cells were different in functional property. Conclusion: CLEM is a useful technique to observe the three-dimensional fine structures of the human vocal fold mucosa. The results of the present study are consistent with the hypothesis that the cells in the MFe of the human vocal fold have heterogeneity and each three types of cell have different properties.

Comparative Histoanatomy of the Epiglottis and Preepiglottic Space of the Lemur Larynx.

OBJECTIVES: An adequate understanding of the evolution of the larynx presumably clarify the physiology and functional histoanatomy of the present-day human organ. This study investigated the comparative histoanatomy of the epiglottis and preepiglottic space of the lemur larynx (a non-human primate without vocal tract). METHODS: Two normal adult ring-tailed lemur larynges obtained from natural death were investigated. The whole organ serial section technique was employed. RESULTS: The histologic structures of the lemur epiglottis and preepiglottic space differed considerably from that of human adults. The lemur epiglottis was proportionally thick and vertical. It was connected to the thyroid cartilage anteroinferiorly without an intervening thyroepiglottic ligament and to the hyoid bone anteriorly with intervening large bundles of collagen fibers, indicating that the lemur epiglottis does not play the role of retroflection. The lemur larynges did not have a preepiglottic space. These findings also reflect the fact that lemurs do not have a descended larynx and do not acquire the pharyngeal space of the vocal tract. The lemur epiglottis was composed of fibrocartilage, adipose tissue and a small amount of elastic cartilage covered with mucosa (lamina propria and pseudostratified ciliated columnar epithelium). The histologic findings also indicate that the lemur epiglottis is not flexible and does not play the role of retroflection. CONCLUSIONS: The results of this study are consistent with the hypothesis that, in the process of evolution, the histologic structures of epiglottis and preepiglottic space likely change to make the larynx descend and lengthen the pharyngeal space of the vocal tract for speech production in humans. Moreover, the distribution of the human preepiglottic space likely allows the epiglottis to more effectively play the role of retroflection during swallowing in order to prevent aspiration.

Long-Term Effects of Fat Injection Laryngoplasty in Relation to the Injected Fat Volume in Patients With Unilateral Vocal Fold Paralysis.

OBJECTIVE: To evaluate the improvements in vocal function and glottal form before and after autologous fat injection laryngoplasty in relation to the injected total fat volume in patients with unilateral vocal fold paralysis. DESIGN: Clinical study. METHODS: Seventy-three patients with unilateral vocal fold paralysis received fat injection laryngoplasty and were divided into low-volume injection (<3 mL; average, 2.0 mL) and high-volume injection (≥3 mL; average, 4.3 mL) groups. Voice function before and after fat injection laryngoplasty were examined by aerodynamics evaluations, pitch and intensity measurements, and acoustic analyses. The glottal form before and after fat injection laryngoplasty was determined by measuring the ratio of vocal fold bowing (bowing ratio) and the ratio of lengths between bilateral vocal process (width ratio) at an easy phonation under laryngeal endoscopic examination. The postoperative parameters were evaluated for a median period of four years after fat injection laryngoplasty. The differences between pre- and postoperative parameters were examined separately for each group by the paired t-test. For each variable, a comparison of the effects of surgery was conducted using an analysis of covariance model with the change between the pre- and postoperative values as a dependent variable and the preoperative value as a covariate. RESULTS: In both groups, all parameters of voice function and glottal form after surgery significantly improved in comparison to those before surgery. Maximum phonation time, amplitude perturbation quotient, and normalized noise energy for 0 to 4 kHz in the high-volume group improved more significantly in comparison to those in the low-volume group. CONCLUSIONS: As a rough guide for males, injection of more than 3 mL of autologous fat to the vocal muscle layer is recommended for reliable improvement of voice function in patients with unilateral vocal fold paralysis.

Glycolysis of Tissue Stem Cells in the Macula Flava of Newborn Vocal Fold.

OBJECTIVES: There is growing evidence that the cells in the maculae flavae are tissue stem cells and the maculae flavae are a stem cell niche of the human vocal fold mucosa. This study investigated the metabolic activity, especially glycolysis, of the tissue stem cells in the maculae flavae of the human newborn vocal fold. METHODS: Three normal human newborn vocal folds obtained from autopsy cases were investigated using immunohistochemistry. RESULTS: Among the three phenotypes of cells (cobblestone-like polygonal cells, vocal fold stellate cell-like cells and fibroblast-like spindle cells) in the newborn maculae flavae, a small number of cobblestone-like polygonal cells strongly expressed glucose transporter-1. All three phenotypes of cells in the newborn maculae flavae expressed glycolytic enzymes (hexokinase II, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase A). The cells did not express phosphofructokinase-1 (rate-limiting enzyme of regular glucose metabolism pathway) but sparsely express glucose-6-phosphate dehydrogenase (rate-limiting enzyme) indicating the cells relied more on the pentose phosphate pathway. The cells' expression of lactate dehydrogenase A suggests the maculae flavae of the newborn vocal fold is likely to be an anaerobic microenvironment where cells perform anaerobic glycolysis. CONCLUSIONS: The present study is consistent with the hypothesis that the tissue stem cells in the maculae flavae of the newborn vocal fold seem to rely more on anaerobic glycolysis, especially by the pentose phosphate pathway, for energy supply. Already at birth, the metabolism of the tissue stem cells in the maculae flavae of the newborn vocal fold is likely to prevent the formation of toxic reactive oxygen species and is likely favorable to maintaining the stemness and undifferentiated states of the tissue stem cells in the stem cell system.

Dysphagia Precipitated by Cervical Lordosis in the Aged.

A lordotic curve of the cervical spine in the aged is a physiological curvature of the cervical spine. The swallowing disorder precipitated by lordosis of the cervical spine in the aged, the swallowing function and intervention were reported on. An 86-year-old woman complained of swallowing difficulty for a few months. A lordotic curve (physiological curvature) of the cervical spine was observed. In the neutral neck position, the cervical lordotic angle was 29° using the Cobb C2-C7 method. When the lordotic curve of the cervical spine was intentionally straightened, the lordotic angle became 0°, the laryngeal elevation changed from 0.5 times the height of a cervical vertebra to 1.75 times, the laryngeal elevation delay time changed from 0.5 seconds to 0.23, the percent laryngeal elevation changed from 50% to 72% and pharyngeal transit time changed from 0.83 seconds to 0.75. Lordosis of the cervical spine inhibited laryngeal elevation and influenced the swallowing function. In cases in which lordotic curvature of the cervical spine adversely influences the swallowing function in the aged, rehabilitation to manage the lordosis of the cervical spine is useful. For the purpose of effective intervention, not only diagnostic but also therapeutic videofluorographic examination of swallowing is very important.

Metabolic Roles of Colony-Forming Tissue Stem Cells in the Maculae Flavae of Newborn Vocal Fold In Vivo.

OBJECTIVES: Tissue stem cells in the maculae flavae (a stem cell niche) of the human vocal fold form colonies in vivo like stem cells in vitro. However, the roles of colony-forming aggregated cells in the maculae flavae in vivo have not yet been determined. This study investigated the glycolysis, of the colony-forming aggregated cells in the maculae flavae of the human newborn vocal fold in vivo. METHODS: Three normal newborn vocal folds were investigated under light microscopy with immunohistochemistry and transmission electron microscopy. RESULTS: Colony-forming aggregated cells in the newborn maculae flavae strongly expressed glucose transporter-1 and glycolytic enzymes (hexokinase II, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase A). The colony-forming aggregated cells did not express phosphofructokinase-1 (rate-limiting enzyme of regular glucose metabolism pathway) but expressed glucose-6-phosphate dehydrogenase (rate-limiting enzyme) indicating the cells relied more on the pentose phosphate pathway. The colony-forming aggregated cells' strong expression of lactate dehydrogenase A indicated that they rely more on anaerobic glycolysis in an anaerobic microenvironment. Mitochondrial cristae of the colony-forming aggregated cells in the newborn maculae flavae were sparse. Consequently, the microstructural features of the mitochondria suggested that their metabolic activity and oxidative phosphorylation were low. CONCLUSIONS: The colony-forming aggregated cells in the maculae flavae of the newborn vocal fold seemed to rely more on anaerobic glycolysis using the pentose phosphate pathway for energy supply in vivo. Microstructural features of the mitochondria and the glycolytic enzyme expression of the colony-forming aggregated cells suggested that the oxidative phosphorylation activity was low. Already at birth, in the anaerobic microenvironment of the macular flavae in vivo, there is likely a complex cross-talk regarding metabolism between the colony-forming aggregated cells along the adhesion machinery and chemical signaling pathways which reduces toxic oxygen species and is favorable to maintaining the stemness and undifferentiated states of the tissue stem cells.

Laryngeal spaces in the newborn larynx.

OBJECTIVES: Distributions of laryngeal spaces are important in understanding their functional significance. However, laryngeal spaces in the newborn larynx are enigmatic. METHODS: Five normal human newborn larynges were investigated using whole organ serial section technique. RESULTS: The chief newborn laryngeal spaces were the preepiglottic space, the paraglottic space and the cricoid area. They consisted of an areolar tissue area composed of brown adipose tissue (immature adipose tissue) and loose elastic and collagen fibers. The newborn preepiglottic space was immature and occupied a small area anterior to the epiglottis. The epiglottis lied on a somewhat horizontal axis and was partially obscured behind the hyoid bone. The hyoid bone overlapped the thyroid cartilage, partially obscuring the superior thyroid notch. The thyroid cartilage was present close to the hyoid bone and the thyrohyoid membrane ran between the superior surface of the thyroid lamina, and not the anteroinferior, but the posteroinferior surface of the hyoid bone. The preepiglottic space was located anterior, lateral and posterolateral to the thyroepiglottic ligament. However, the preepiglottic space was located anterior to the epiglottic cartilage. As seen in adults, the paraglottic space existed medial to the lamina of each bilateral thyroid cartilage. Each bilateral cricoid area was located along not only the superomedial but also the medial portion of the cricoid arch on both sides. CONCLUSIONS: As the child grows, the preepiglottic space, occupying a small area anterior to the epiglottis, likely grows as the larynx descends and acquires the human adult vocal tract. From the functional histoanatomical point of view, the newborn laryngeal spaces appear to be favored for respiration and maintenance of a protective sphincter for the lower airway over phonation.

Improvement of the far-infrared optical property for glasses by plasma-assisted dispersion of fluorocarbon species into the shallow surface.

Owing to global warming together with the demands for thermal energy storage in diverse fields, there is demand for transparent glasses achieving reflection of the short-wave far-infrared (IR) light from solar radiation while also absorbing the longer wavelength part. Here, we performed the plasma-assisted ion implantation using a desktop-type low-pressure fluorocarbon plasma generator system to improve the optical properties of transparent soda-lime glasses. Investigations using positron annihilation techniques for the plasma-treated glass demonstrated that the fluorocarbon species occupy the sub-nanoscale interstitial sites available in the glass network of the soda-lime glass as the intrinsic open spaces, forming an implantation layer in the shallow-surface region around a depth of 50 nm. As revealed by optical spectroscopy, the subsurface layer, due to the implanted fluorocarbon species, significantly cuts off the short-wave far-IR light around a wavelength of ∼3 µm and also acts as the absorber of the longer wavelength region from 7 to 12 µm. Plasma treatment could be a promising tool to improve the optical properties in the IR light region for various materials.

An Optimal Timing for Removing a Drain After Breast Surgery: A Systematic Review and Meta-Analysis.

BACKGROUND: In clinical practice, drains had been routinely used for reducing seroma formation after breast surgery. However, an optimal timing to remove drains does not identify yet. METHODS: This study aimed to compare the clinical outcome, such as seroma formation, surgical site infection (SSI), and a length of hospital stay between early removal and late removal. A systematic review was performed using PubMed, MEDLINE, and the Cochrane Library. Breast cancer patients who received surgery using drains were eligible. Those parameters were compared between early vs late removal. RESULTS: Eleven studies included in this meta-analysis. Seroma formation in the early removal group was significantly higher than the one in the late removal group (RR = 1.58: 95%CI [1.25-2.01], P = 0.0001), meanwhile no significant difference was found among the groups for SSI (RR = 0.82: 95%CI [0.51-1.31], P= 0.40). A length of hospital stay in the early removal group was also significantly shorter than late removal (RR -3.31: 95%CI [-5.13-1.49], P = 0.0004). CONCLUSIONS: Seroma formation was significantly higher in patients who had early drain removal. Conversely, SSI incidence was low, and early removal did not increase SSI incidence. In conclusion, early drain removal has no proved clinical benefit in these settings besides reduction of hospital stays.

Role of colony-forming tissue stem cells in the macula flava of the human vocal fold in vivo.

OBJECTIVES: Our previous investigations showed that tissue stem cells in the maculae flavae (a stem cell niche) form colonies in vivo like stem cells in vitro. However, the roles of colony-forming cells in the maculae flavae in vivo have not yet been determined.This study investigated the metabolism of the colony-forming tissue stem cells in the maculae flavae of the human adult vocal fold. STUDY DESIGN: Histologic analysis of the human vocal folds. METHODS: Three normal human adult vocal folds were investigated under transmission electron microscopy and light microscopy including immunohistochemistry. RESULTS: Mitochondrial cristae of the colony-forming cells in the maculae flavae were sparse. Hence, the microstructural features of the mitochondria suggested that their metabolic activity and oxidative phosphorylation were low. Colony-forming cells strongly expressed glucose transporter-1 and glycolytic enzymes (hexokinase II, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase A). The colony-forming cells did not express phosphofructokinase-1 but did express glucose-6-phosphate dehydrogenase indicating the cells relied more on the pentose phosphate pathway. Since the colony-forming cells expressed lactate dehydrogenase A, cells seemed to rely more on anaerobic glycolysis in an anaerobic microenvironment. CONCLUSIONS: The present study is consistent with the hypothesis that the colony-forming tissue stem cells in the maculae flavae of the human adult vocal fold seemed to rely more on anaerobic glycolysis using the pentose phosphate pathway for energy supply in vivo. Microstructural features of the mitochondria and expressed glycolytic enzymes of the colony-forming cells in the maculae flavae suggested that the oxidative phosphorylation activity was low.In an anaerobic microenvironment in vivo, there is likely a complex cross-talk regarding the metabolism between the colony-forming aggregated cells along the adhesion machinery and chemical signaling pathways, which reduces toxic oxygen species and is favorable to maintaining the stemness and undifferentiated states of the tissue stem cells. LEVEL OF EVIDENCE: NA.

Glycolytic activity of the tissue stem cells in the macula flava of the human vocal fold.

OBJECTIVES: In our previous studies, the features of the mitochondria of tissue stem cells in the maculae flavae of the human vocal fold suggested that their metabolic activity and oxidative phosphorylation was low. This study investigated the metabolic activity, especially glycolysis of the tissue stem cells in the maculae flavae of the human adult vocal fold. STUDY DESIGN: Histologic analysis of the human vocal folds. METHODS: Three normal human adult vocal folds obtained from autopsy cases were investigated using immunohistochemistry. RESULTS: Among the three phenotypes of cells in the human adult maculae flavae, the vocal fold stellate cell-like cells strongly expressed glucose transporter-1. Three phenotypes of cells in the human adult maculae flavae expressed glycolytic enzymes (hexokinase II, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase A) indicating the tissue stem cells in the maculae flavae relied more on glycolysis. The cells did not express phosphofructokinase-1 but did express glucose-6-phosphate dehydrogenase indicating the cells relied more on the pentose phosphate pathway. The cells expressed lactate dehydrogenase A indicating the maculae flavae of the human adult vocal fold was likely to be an anaerobic microenvironment. CONCLUSIONS: The present study is consistent with the hypothesis that the tissue stem cells in the maculae flavae of the human vocal fold seem to rely more on anaerobic glycolysis, especially by the pentose phosphate pathway, for energy supply. The metabolism of the tissue stem cells in the maculae flavae of the human adult vocal fold is likely to prevent toxic reaction oxygen species and be favorable to maintaining the stemness and undifferentiated states of the tissue stem cells in the stem cells system. LEVEL OF EVIDENCE: NA.

Pathophysiology of current odontogenic maxillary sinusitis and endoscopic sinus surgery preceding dental treatment.

OBJECTIVE: The successful management of odontogenic maxillary sinusitis (OMS) involves a combination of medical treatment with dental surgery and/or endoscopic sinus surgery (ESS). However, there is no consensus for the optimal timing of ESS. Although several studies have emphasized dental surgery as the primary treatment modality for OMS, there is recent evidence to suggest that ESS alone may be an effective treatment approach. The purpose of this study is to retrospectively investigate the pathophysiology of the current intractable OMS and the role ESS, especially ESS preceding dental treatment, plays in its pathophysiology. METHODS: Ninety-seven adults (60 males and 37 females, 48 ± 12 years) who underwent ESS for intractable OMS were retrospectively examined. RESULTS: In a great deal of the cases (85 cases, 87.6%), causative teeth of OMS were periapical lesions after root canal treatment (endodontics). The root canal procedures were not sufficient; hence, the root-canal-treated teeth had periapical lesions causing OMS. In postoperative nasal endoscopy and cone-beam CT scans for all patients, the natural ostiums and the membranous portions of the maxillary sinuses were enlarged and the ostiomeatal complexes remained widely open. The ventilation and drainage of all patients' maxillary sinuses seemed to be successfully restored. Temporary acute sinusitis recurrence after primary ESS for OMS was observed in 10 cases (11.8%) when the patients caught a cold. However, since the natural ostium and the membranous portion of the maxillary sinuses and the ostiomeatal complexes remained widely open, antibiotic administration alone without dental treatment cured the temporary acute sinusitis. Regarding the causative teeth (endodontic treated teeth), in 83 out of 85 cases (97.6%), causative teeth were able to be preserved with only antibiotic treatment and without dental retreatment. In two cases, extraction of the teeth was necessary because the teeth became mobile. Regarding the causative teeth after dental restoration, in 2 out of 2 cases (100%), causative teeth were able to be preserved with antibiotic treatment alone. CONCLUSION: ESS is highly indicated for OMS requiring surgery. The treatment results of intractable OMS are exceptionally good once the ventilation and drainage of the maxillary sinus is successfully restored after surgery. Consequently, ESS can be considered the first-line therapy for intractable OMS caused by root canal treatment (endodontics) and dental restoration, followed by close dental follow-up and dental treatment when necessary.