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Biomedical subjects

Atsuko Tanaka

Publications and source records attributed to Atsuko Tanaka.

At least 19 recordsLinked to original sources
PubMed2006

Insulin and nateglinide reduce monocyte adhesion to endothelial cells in Goto-Kakizaki rats exhibiting repetitive blood glucose fluctuation.

Epidemiological studies demonstrated the importance of postprandial hyperglycemia on the progression of atherosclerosis. However, whether treatment of postprandial hyperglycemia by insulin or insulin secretagogues has a beneficial effect on atherosclerosis has not been elucidated. To elucidate the effects of reduction of postprandial rise of blood glucose by insulin and nateglinide on monocyte adhesion to endothelial cells, we used non-obese type 2 diabetic Goto-Kakizaki (GK) rats fed twice daily, as a model of repetitive postprandial hyperglycemia. We investigated the effects of insulin injection and nateglinide administration just before each meal for 12 weeks on monocyte adhesion to endothelial cells. By setting the doses of insulin and nateglinide, both treatment significantly reduced postprandial hyperglycemia without significant reduction of HbA1c. Nateglinide also reduced serum insulin level just after 1 h meal. Both nateglinide and insulin therapy reduced the number of monocytes adherent to the aortic endothelial layer. Nateglinide, but not insulin, reduced intimal thickness of the thoracic aorta. While increased serum insulin level might be regarded as a factor responsible for the progression of atherosclerosis, our data showed that treatment with pre-meal insulin or nateglinide, which reduces postprandial hyperglycemia, reduced monocyte adhesion to endothelial cells.

Animals↗
PubMed2006

Fractional sodium excretion, urinary osmolality and specific gravity in preterm infants fed with fortified donor human milk.

OBJECTIVE: This research was performed with the objective of investigating the renal effects on premature newborn infants of fortifying banked donor human milk. METHODS: Clinical intervention trial, of the before-and-after type, involving 28 premature newborn infants split into two groups by postconceptional age at the start of the study: GI < 34 weeks (n = 14) and GII >or= 34 weeks (n = 14), and assessed at three sample points: S1, on unfortified donor human milk, S2, after 3 days, and S3, after 10-13 days on fortified donor human milk. Nutrient intake, weight gain, fractional sodium excretion, urinary osmolality and specific density were compared with two-way ANOVA for repeated measures. RESULTS: Fluids, energy and sodium intakes were similar for both groups, and weight gain was satisfactory. Among the preterms with < 34 weeks postconceptional age, serum sodium was lower at the end of the study and the fractional sodium excretion was elevated at the start and at the end of the study (S1 = 2.11+/-1.05; S2 = 1.25+/-0.64; S3 = 1.62+/-0.88), with a significant difference in relation to GII (S1 = 1.34+/-0.94; S2 = 0.90+/-0.54; S3 = 0.91+/-0.82). Osmolality and urinary specific density were normal, with no differences between groups or collection dates. CONCLUSIONS: No adverse effects on the renal function of these preterms were detected as a result of being fed fortified donor human milk.

Analysis of Variance↗
PubMed2006

Acarbose, an alpha-glucosidase inhibitor, improves endothelial dysfunction in Goto-Kakizaki rats exhibiting repetitive blood glucose fluctuation.

Several epidemiological studies have revealed that subjects with postprandial hyperglycemia are at increased risk of cardiovascular disease. However, the impact of postprandial hyperglycemia and its treatment on endothelial function has not been clarified yet. In this study, Goto-Kakizaki (GK) rats, a non-obese type 2 diabetes model, fed twice daily were used as a model of repetitive postprandial glucose spikes. We investigated the endothelial function in these rats treated or untreated with acarbose, an alpha-glucosidase inhibitor. Administration of acarbose for 12 weeks markedly improved postprandial hyperglycemia, postprandial insulin level, total cholesterol, triglyceride, and free fatty acid level in GK rats. Furthermore, acarbose efficiently reduced the number of monocytes adherent to aortic endothelial layer, improved acetylcholine-dependent vasodilatation, and reduced intimal thickening of the aorta. While it is generally regarded that repetitive postprandial hyperglycemia is associated with the onset of cardiovascular diseases, our data demonstrated that acarbose treatment efficiently ameliorated endothelial dysfunction and reduced intimal thickening, thus adding support to the protective effect of acarbose against the onset of cardiovascular disease.

Acarbose↗
PubMed2006

[Three cases of corneal disorders associated with an oral anticancer drug S-1].

PURPOSE: S-1 is a new oral anticancer drug containing tegafur, which is a prodrug of 5-fluorouracil. In this report, we describe the clinical features of three patients who suffered corneal disorders that seemed to be caused by S-1 administration. CASES: One female and two male patients, whose ages ranged from 57 to 69 years, were entered in this study. Between 3 to 14 months after they started oral S-1 therapy, they experienced sudden visual reduction. They all had corneal disorders, which occurred in the inferior and the superior areas, and progressed toward the center. As the corneal disorders invaded the pupil area, the patients noticed visual disturbance. They recovered their vision and their corneal disorders diminished when the drug was discontinued. However, after the drug intake was resumed, the corneal disorders occurred again in some cases. All patients also had lacrimal obstructions. CONCLUSION: S-1 treated patients should be followed carefully for ophthalmic complications because corneal disorders are likely to appear.

Administration, Oral↗
PubMed2005

Laryngeal reflex before and after placement of airway interventions: endotracheal tube and laryngeal mask airway.

BACKGROUND: Previous reports indicate that detrimental laryngeal function persists over several hours after tracheal extubation even in patients who have regained full consciousness from anesthesia. The authors hypothesize that even after minor surgery, the presence of an endotracheal tube (ETT) impairs the receptors at the vocal cord and diminishes the defensive laryngeal function. The hypothesis was tested by comparing types of experimentally induced laryngeal airway reflexes before and after surgery in anesthetized patients with use of either an ETT or a Laryngeal Mask Airway. METHODS: Twenty adult patients undergoing elective minor surgeries were randomly allocated into two groups, the ETT and Laryngeal Mask Airway groups, depending on the airway management method used during surgery. While maintaining sevoflurane at 1 minimum alveolar concentration, laryngeal and respiratory responses were elicited by instillation of distilled water on the vocal cords immediately before and after surgery. Furthermore, the vocal cord angles were endoscopically measured under complete paralysis. RESULTS: Some laryngeal reflex responses of both groups, particularly the cough reflex, were significantly attenuated after minor surgery. Significant narrowing of the glottic aperture was evident in patients with ETT placement but not in patients with Laryngeal Mask Airway placement. CONCLUSIONS: With either airway intervention, laryngeal defensive reflexes are depressed immediately after surgery even without visible laryngeal swelling. The sensory impairment attributable to the presence of an ETT cannot be the solo factor responsible for the modification of the defensive airway reflexes elicited from the larynx.

Adult↗
PubMed2005

Sniffing position improves pharyngeal airway patency in anesthetized patients with obstructive sleep apnea.

BACKGROUND: Appropriate bag-and-mask ventilation with patent airway is mandatory during induction of general anesthesia. Although the sniffing neck position is a traditionally recommended head and neck position during this critical period, knowledge of the influences of this position on the pharyngeal airway patency is still inadequate. METHODS: Total muscle paralysis was induced with general anesthesia in 12 patients with obstructive sleep apnea, eliminating neuromuscular factors contributing to pharyngeal patency. The cross-sectional area of the pharynx was measured endoscopically at different static airway pressures. Comparison of static pressure-area plot between the neutral and sniffing neck positions allowed assessment of the influence of the neck position change on the mechanical properties of the pharynx. RESULTS: The static pressure-area curves of the sniffing position were above those of neutral neck position, with increasing maximum cross-sectional area and decreasing the closing pressure at both retropalatal and retroglossal airways. The beneficial effects of the sniffing position were greater in obstructive sleep apnea patients with higher closing pressure and smaller body mass index. CONCLUSIONS: Sniffing position structurally improves maintenance of the passive pharyngeal airway in patients with obstructive sleep apnea and may be beneficial for both mask ventilation and tracheal intubation during anesthesia induction.

Adult↗
PubMed2005

Airway protective reflexes evoked by laryngeal instillation of distilled water under sevoflurane general anesthesia in children.

To investigate how sevoflurane modifies airway protective reflexes in anesthetized children, we recruited patients younger than 12-yr-old for our study. Anesthesia was induced with inhaled sevoflurane in oxygen. The airway was managed with a laryngeal mask airway and the patient breathing spontaneously. Depending on the depth of anesthesia, the subjects were divided into two groups: Group 1 and Group 2 (1% and 2% of end-tidal sevoflurane concentration, respectively). Behaviors of the larynx were assessed mainly by the fiberscopic images of the larynx as well as respiratory flow and esophageal pressure. A small dose, 0.02 mL/kg of distilled water (minimum 0.2 mL) was instilled to the larynx through a channel of the scope to evoke an airway protective reflex from the larynx. The responses were categorized into passive (laryngeal closure, laryngospasm, and apnea) and active (cough, expiration reflex, and swallowing reflex) responses. Ten subjects were included in each group. In both groups, the primary responses were passive; however, in Group 1, active reflexes were also observed in 8 of 10 subjects; no subjects in Group 2 had active reflexes (P < 0.01). We concluded that, in children, the depth of general anesthesia with sevoflurane modified airway protective reflexes.

Anesthesia, General↗
PubMed2004

Influences of head positions and bite opening on collapsibility of the passive pharynx.

A collapsible tube surrounded by soft material within a rigid box was proposed as a two-dimensional mechanical model for the pharyngeal airway. This model predicts that changes in the box size (pharyngeal bony enclosure size anatomically defined as cross-sectional area bounded by the inside edge of bony structures such as the mandible, maxilla, and spine, and being perpendicular to the airway) influence patency of the tube. We examined whether changes in the bony enclosure size either with head positioning or bite opening influence collapsibility of the pharyngeal airway. Static mechanical properties of the passive pharynx were evaluated in anesthetized, paralyzed patients with sleep-disordered breathing before and during neck extension with bite closure (n = 11), neck flexion with bite closure (n = 9), and neutral neck position with bite opening (n = 11). Neck extension significantly increased maximum oropharyngeal airway size and decreased closing pressures of the velopharynx and oropharynx. Notably, neck extension significantly decreased compliance of the oropharyngeal airway wall. Neck flexion and bite opening decreased maximum oropharyngeal airway size and increased closing pressure of the velopharynx and oropharynx. Our results indicate the importance of neck and mandibular position for determining patency and collapsibility of the passive pharynx.

Adult↗
PubMed2004

Inspiratory activation of the vocal cord adductor, part I: human study in patients with restricted abduction of the vocal cords.

OBJECTIVES/HYPOTHESIS: In patients with restricted abduction of the vocal cords, it has generally been accepted that glottis narrowing with laryngeal stridor during inspiration is attributed to static and passive obstruction of the glottis. However, active glottis narrowing can also be contributory. We tested the hypothesis that the vocal cord adductor is activated during inspiration in patients with restricted abduction of the vocal cords. STUDY DESIGN: Electromyographic evaluation of vocal cord adductor activity in patients with restricted abduction of the vocal cords. METHODS: Five patients with restricted abduction of the vocal cords who had stridor with mild to severe dyspnea during wakefulness were anesthetized with propofol. We recorded the adductor muscle electromyogram during breathing through a laryngeal mask airway while observing the vocal cord movement endoscopically. In three patients who had undergone tracheostomy, we also recorded adductor firing patterns not only while closing but also while opening the tracheostoma. RESULTS: The adductor was activated during inspiration, and the glottis was narrowed in accordance with inspiratory stridor. This adductor inspiratory activity was abolished by opening the tracheostoma in the tracheostomized patients. CONCLUSION: Not only static or passive glottis narrowing but also active narrowing may contribute to inspiratory flow limitation in patients with restricted abduction of the vocal cords. This active glottis narrowing is probably induced by an airway reflex.

Adolescent↗
PubMed2004

[Experience using an improved bronchial blocker (Phycon TCB bronchial blocker)].

We recently had opportunities to use an improved bronchial blocker (Phycon TCB bronchial blocker) in surgical patients who needed separation of the lungs and/or one-lung ventilation. This blocker provides a high torque control and can be easily manipulated into the desired site of the lungs. Our clinical experience shows that this blocker is useful particularly when the quick and sure separation of the lungs is crucial or when the insertion of a double-lumen tube is very difficult.

Bronchi↗
PubMed2003

Dynamic interaction between the tongue and soft palate during obstructive apnea in anesthetized patients with sleep-disordered breathing.

Little is known about the mechanisms of persistence of obstructive apnea. Structurally, the dorsum of the tongue locates anterior to the soft palate. On the basis of the observation of posterior displacement of the tongue during obstructive apnea, we hypothesized that the dorsum of the tongue pushes the anterior wall of the soft palate posteriorly during inspiratory efforts, maintaining closure at the retropalatal airway. To test this hypothesis, we measured the pressure between dorsum of the tongue and anterior wall of the soft palate (PT&P) during experimentally induced obstructive apneas in anesthetized patients with sleep-disordered breathing. P(T&P) changes during the obstruction significantly depended on collapsibility of the retroglossal airway. Progressive increase in the P(T&P) during obstructive apnea was observed only in patients with highly collapsible retroglossal airways. Significant increase in the P(T&P) during inspiratory effort in accordance with positive deflection pattern of P(T&P) tracing was evident in the patients with highly collapsible retroglossal airways. The results indicate significant dynamic interaction between the tongue and soft palate during both obstructive apnea and each inspiratory effort, possibly maintaining closure at the retropalatal airway.

Adult↗
PubMed2003

Laryngeal resistance before and after minor surgery: endotracheal tube versus Laryngeal Mask Airway.

BACKGROUND: The placement of an endotracheal tube (ETT) may promote laryngeal swelling, which is an important cause of upper airway obstruction after extubation. The authors hypothesized that laryngeal swelling after ETT placement increases laryngeal resistance and tested that hypothesis by comparing postoperative laryngeal patency between patients with ETT placement and those with a Laryngeal Mask Airway trade mark (LMA). METHODS: Fourteen adult patients who underwent elective minor surgeries were randomly allocated to two groups whose airway would be managed through ETTs (the ETT group) or LMAs (the LMA group) during the surgery. While maintaining at sevoflurane 1 minimum alveolar concentration, the authors measured laryngeal resistance before and after surgery, during both spontaneous breathing and mechanical ventilation under complete paralysis. In addition, they endoscopically measured the vocal cord angle under complete paralysis. RESULTS: In association with marked swelling of the vocal cords, the vocal cord angle significantly decreased after surgery in the ETT group, whereas the angle did not change in the LMA group. Laryngeal resistance during mechanical ventilation significantly increased only in the ETT group. Laryngeal resistance during spontaneous breathing significantly increased after surgeries in both groups. CONCLUSIONS: Postoperative laryngeal resistance increases at least in part because of laryngeal swelling in patients with ETT placement, whereas alteration of laryngeal neural control mechanisms has been also indicated. The use of the LMA trade mark has an advantage over ETT placement in order to avoid postoperative laryngeal swelling.

Adult↗
PubMed2003

Effects of uvulopalatopharyngoplasty on collapsibility of the retropalatal airway in patients with obstructive sleep apnea.

OBJECTIVES/HYPOTHESIS: Uvulopalatopharyngoplasty improves sleep-disordered breathing, particularly in patients with sleep-disordered breathing with abnormally high collapsible airway exclusively at the retropalatal airway, as was previously reported. The present study examined the direct and long-term effects of uvulopalatopharyngoplasty on retropalatal airway collapsibility. STUDY DESIGN: Prospective longitudinal study of 18 patients with abnormally high collapsible airway exclusively at the retropalatal airway. METHODS: Closing pressure of the retropalatal airway was estimated by endoscopically obtaining static pressure/area relationship of the passive pharynx in completely paralyzed and anesthetized patients with sleep-disordered breathing (n = 18) before and 3 months after uvulopalatopharyngoplasty. The measurements were repeated 1 year after uvulopalatopharyngoplasty in eight of these patients. RESULTS: Uvulopalatopharyngoplasty decreased retropalatal airway closing pressure by 3.5 cm H2O; furthermore, a direct correlation between the severity of sleep-disordered breathing (as determined by nocturnal oximetry) and retropalatal airway closing pressure was revealed. Uvulopalatopharyngoplasty failures revealed retropalatal airway closing pressure greater than atmospheric pressure. Reduced retropalatal airway collapsibility was maintained up to 1 year after uvulopalatopharyngoplasty. Two patients developed marked stenosis of the retropalatal airway with aggravation of sleep-disordered breathing after initial improvement of sleep-disordered breathing and retropalatal airway collapsibility. CONCLUSIONS: Uvulopalatopharyngoplasty decreases the retropalatal airway collapsibility. The effect is maintained for at least 1 year after uvulopalatopharyngoplasty, whereas a few patients develop retropalatal airway stenosis leading to recurrence of sleep-disordered breathing.

Adult↗
PubMed2002

Prone position increases collapsibility of the passive pharynx in infants and small children.

On the basis of two observations that avoiding prone sleeping decreased incidence of sudden infant death syndrome and that obstructive sleep apnea is closely linked with the syndrome, we hypothesized that the prone position may increase upper airway collapsibility in infants and small children. Passive pharyngeal collapsibility of 19 infants and small children (10-101 weeks old) was examined in three postures: supine with face straight up, supine with neck rotated, and prone with neck rotated. The collapsibility was evaluated with the maximal distension of the most collapsible region, pharyngeal stiffness, and pharyngeal closing pressure, estimated from static pressure-area relationship of the passive pharynx. No significant changes in pharyngeal stiffness were detected; however, maximal distension was reduced in the prone position (mean +/- SD, 0.56 +/- 0.26 versus 0.44 +/- 0.20 cm(2); supine with face straight up versus prone position, p < 0.05). Pharyngeal closing pressure increased at neck rotation in the supine position (-4.5 +/- 2.4 versus -2.8 +/- 2.3 cm H(2)O; supine with face straight up versus supine with neck rotated, p < 0.05), and a further increase was observed in the prone position (-0.3 +/- 2.9 cm H(2)O, p < 0.05 versus supine with neck rotation). Pharyngeal closing pressure in the prone position was above atmospheric pressure in half of our subjects, whereas all subjects had negative pharyngeal pressure in the supine position. We conclude that the prone position increases upper airway collapsibility, although the mechanism is yet unclear.

Airway Resistance↗
PubMed2002

Contribution of body habitus and craniofacial characteristics to segmental closing pressures of the passive pharynx in patients with sleep-disordered breathing.

Obesity and craniofacial abnormalities may contribute to the pathogenesis of obstructive sleep apnea. The purpose of this study was to evaluate the influence of body habitus and craniofacial characteristics on types of pharyngeal closure. The types of pharyngeal closure were determined by endoscopic evaluations of closing pressures of the passive pharynx in 54 paralyzed and anesthetized patients with sleep-disordered breathing (SDB). Assessment of craniofacial characteristics of the SDB patients and 24 normal subjects were made by lateral cephalometry. As compared with normal subjects, SDB patients demonstrated receded mandibles and long lower faces with downward mandible development. SDB patients with positive closing pressures at both the velopharynx and oropharynx (VP + OP group) demonstrated smaller maxillas and mandibles than those with positive closing pressures at the velopharynx only (VP-only group). Obesity was more prominent in the VP-only group than in the VP + OP group. Our results suggest that obesity and craniofacial abnormalities contribute synergistically to increases in collapsibility of the passive pharyngeal airway in patients with SDB. Furthermore, the relative contribution of obesity and craniofacial anomaly appears to determine the type of pharyngeal closure in SDB.

Adult↗
PubMed2002

Gene expression of TrkC (NTRK3) in human soft tissue tumours.

TrkC is a member of the Trk family of tyrosine kinase receptors and plays an important role in the development and maintenance of neural tissues. Although a variety of non-neuronal tissues have also been shown to express TrkC, the status of TrkC in soft tissue tumours has been poorly investigated, except for a small fraction of tumours including congenital/infantile fibrosarcoma characterized by an ETV6-NTRK3 (also known as Tel-TrkC) fusion gene. To broaden knowledge about the TrkC status in human neoplasms, the expression of TrkC transcripts was assessed in 51 soft tissue tumours of variable lines of differentiation by reverse transcription-polymerase chain reaction (RT-PCR), using primer sets flanking their extracellular domain, the tyrosine kinase domain, and the intracellular domain of a truncated variant (Trunc 1) described previously. In 44 of the 51 tumours, TrkC transcripts, including alternatively spliced isoforms, were detected. The truncated transcripts (Trunc 1) were co-expressed in 40 of the 44 tumours and were expressed in one tumour without native TrkC gene expression. In two of the remaining six tumours, part of the sequence coding the tyrosine kinase domain of TrkC appeared to be truncated. Using a 3' rapid amplification of cDNA ends (3'RACE) method, another truncated isoform (Trunc 2) was isolated from one of the tumours, in which the TrkC transcript was terminated with a novel 160-base pair sequence. This truncated isoform was identified in nine of the 51 tumours examined by RT-PCR using primers for Trunc 2. There was no clear correlation between the types of TrkC isoforms detected and histological types or grades of the tumours. These results suggest that human soft tissue tumours widely express TrkC, irrespective of their cellular lineage, morphology, and biological behaviour. Dysregulated TrkC expression may enhance overgrowth or transformation of various mesenchymal cells.

Amino Acid Sequence↗