Biomedical subjects

T Okada

Publications and source records attributed to T Okada.

At least 271 records · Page 15Linked to original sources

PubMed1999

Patient-reported quality of life after radical prostatectomy for prostate cancer.

BACKGROUND: Increasingly, quality of life (QOL) assessments are receiving greater attention in the management of malignancies, including prostate cancer. We evaluated the impact of radical prostatectomy on patient QOL 12 months or longer after surgery. PATIENTS AND METHODS: We evaluated the impact of radical prostatectomy on QOL in 60 patients with prostate cancer. The patients comprised two groups: the first group (n = 32) was evaluated 12 months or longer after radical prostatectomy; the second group (n = 28) was evaluated while awaiting radical prostatectomy. General health-related QOL was measured with the European Organization for Research and Treatment of Cancer Prostate Cancer QOL Questionnaire. Sexual function was assessed with the Sapporo Medical University Sexual Function Questionnaire. A newly developed instrument assessing urinary function was prepared only for the postoperative group. RESULTS: No differences between the two groups were seen in comparisons of general health-related QOL subscales. Men who underwent surgery reported significant deterioration in sexual function (decreased quality of erection, decreased sexual activity and decreased satisfaction with sex life) than those awaiting surgery. Of the 32 postoperative patients, 26 (81%) did not use pads at all, five (16%) used one or fewer pads per day due to occasional spotting and only one patient (3%) used two to four pads per day to deal with urine dripping. Twenty-six postoperative patients (81%) stated that, given the choice, they would undergo radical prostatectomy again. CONCLUSIONS: General health-related QOL does not appear to be compromised following radical prostatectomy. Patients are willing to accept some morbidity for a perceived survival benefit. Although minimal urinary dysfunction was reported, most patients were dissatisfied with postoperative sexual function. In preoperative counselling, greater emphasis should be placed on the risk of postoperative impotence.

Aged↗

PubMed1999

AMPA-preferring receptors with high Ca2+ permeability mediate dendritic plasticity of retinal horizontal cells.

The synaptic complex formed by the cone photoreceptor pedicles and the dendrites of horizontal cells in the teleost retina undergoes structural changes during light adaptation. Numerous spinules are formed by the terminal dendrites, and they are subsequently retracted during dark adaptation. In a retina kept under continuous illumination, the retraction process can be initiated by analogues of the neurotransmitter glutamate acting at AMPA/kainate receptors. On the other hand, the retraction process depends on calcium influx and the subsequent activation of CaMkII. We show here that the retraction of spinules induced by AMPA or kainate is not impaired in the presence of cobalt, making an involvement of voltage-gated calcium channels unlikely. Using calcium imaging techniques with isolated horizontal cells, we demonstrate that AMPA and kainate, but not NMDA, increase [Ca2+]i in the presence of nicardipine, caffeine and thapsigargin. The increase of [Ca2+]i under these conditions depends on [Ca2+]o and on the agonist in a dose-dependent manner, suggesting that the increase of [Ca2+]i is largely due to calcium influx through the agonist-gated channel. Pharmacological studies were performed to determine whether AMPA- and/or kainate-preferring receptors mediate the calcium influx. The AMPA-preferring receptor antagonist LY303070 blocked glutamate- and kainate-evoked increases of [Ca2+]i in a concentration-dependent manner, indicating that kainate-preferring receptors contributed little or nothing to the observed [Ca2+]i increase. This was supported by experiments where cyclothiazide (which blocks the desensitization of AMPA receptors) and concanavalin A (which potentiates responses mediated by kainate receptors) were applied. In all cases, LY303070 blocked the agonist-evoked increase of [Ca2+]i. The presence of AMPA-preferring receptors with high Ca2+ permeability on horizontal cells was also supported by measuring agonist-induced currents using whole-cell recording techniques. Furthermore, LY303070 was able to impair the retraction of spinules during dark adaption in the in vivo situation.

Animals↗

PubMed1999

Li+ and muscarine cooperatively enhance the cationic tail current in rat cortical pyramidal cells.

Li+ is known to facilitate the onset of status epilepticus induced by cholinergic stimulation, although the underlying mechanisms are not clear. Under whole-cell current clamp conditions with a CsCl-based internal solution, cortical pyramidal cells display a single plateau-spike followed by a slow depolarizing afterpotential (DAP) in response to injection of a short current pulse. However, the same current pulse generated a burst of plateau-spikes after application of Li+ (2 mM) and muscarine (10 microM). As similar bursts of plateau-spikes were generated through an enhancement of the slow DAP when [K+]o was raised (Kang et al. 1998), we have investigated the effects of Li+ and muscarine on the Ca2+-dependent cationic current underlying the slow DAP, measured as the slow tail current evoked after the offset of depolarizing voltage pulses. Muscarine enhanced the amplitudes of both early and late components of the slow tail current. This effect of muscarine was markedly potentiated by Li+, while Li+ by itself affected the slow tail current only slightly. Intracellular application of heparin (0.5-1 mg/mL) suppressed the effect of muscarine in the presence of Li+. These results suggest that inositol-trisphosphate-induced Ca2+ release is involved in the cooperative enhancement of the slow tail current, and this cooperation may be one of the mechanisms underlying facilitation of the onset of epilepsy induced by these agents.

Animals↗

PubMed1999

Low-density lipoprotein apheresis retards the progression of hyperlipidemic overt diabetic nephropathy.

BACKGROUND: Hyperlipidemia has recently received attention as being involved in the progression of diabetic nephropathy (DN). Low-density lipoprotein apheresis (LDL-A) can remove a large amount of plasma lipid directly from the patients in a short time. METHODS: Fifteen type 2 diabetic patients with overt nephropathy received LDL-A in two different manners: short-term intensive therapy (SIT) for nine patients and long-term intermittent therapy (LIT) for six patients. RESULTS: The changes in the monthly decline rates of reciprocal serum creatinine (1/Cr) were -0.035 +/- 0.020 in the three-month period before SIT, 0.047 +/- 0.041 during and until two weeks after SIT, and -0.035 +/- 0.015 after a period of two weeks from the therapy. The mean duration of LIT in six patients was 8.2 +/- 7.4 months, and the mean monthly decline rates of 1/Cr significantly decreased during the period of LIT as compared with the six-month period before the treatment. CONCLUSION: LDL-A can retard the progression of overt DN, especially when it is performed repeatedly for a long period at two-week intervals.

Aged↗

PubMed1999

Vestibular perception of angular velocity in normal subjects and in patients with congenital nystagmus.

A technique is described for the assessment of vestibular sensation. The two main goals of the study were (i) to compare the perception of angular velocity with the eye velocity output of the vestibulo-ocular reflex and (ii) to study vestibular function in patients with congenital nystagmus; this was needed since most previous studies, based on eye movement recordings, have been inconclusive. Subjects indicated their perceived angular velocity by turning by hand a wheel connected to a tachometer. The vestibular stimuli used consisted of sudden deceleration from rotation at a constant horizontal velocity of 90 degrees /s ('stopping' responses). Eye movements were recorded simultaneously with electro-oculography. In normal subjects the perceived angular velocity decayed from the moment of deceleration in an exponential fashion. The mean time constant of sensation decay was approximately 16 s. Eye movement velocity decayed with a similar exponential trajectory (time constant 16 s). Congenital nystagmus patients showed markedly shortened vestibular sensation (mean time constant 7 s). The following conclusions can be drawn: (i) the similarity of the eye velocity and perceptual responses suggests that these two systems receive a vestibular signal which has been similarly processed; (ii) the time constant of the responses indicates that this vestibular signal probably originates in the same brainstem 'velocity storage' integrator; (iii) the technique described is useful for clinical assessment of vestibular function, particularly in patients with ocular motility disorders; (iv) patients with congenital nystagmus have short vestibular time constants, which is probably due to changes induced in velocity storage processing by the persistent retinal image motion present in these patients.

Adult↗

PubMed1999

Dietary prevention of azoxymethane-induced colon carcinogenesis with rice-germ in F344 rats.

The modifying effect of dietary administration of defatted rice-germ and gamma-aminobutyric acid (GABA)-enriched defatted rice-germ on azoxymethane (AOM)-induced colon carcinogenesis was investigated in two experiments with male F344 rats. In the first experiment (the pilot study), the effects of the defatted rice-germ, the GABA-enriched defatted rice-germ and rice-germ on AOM-induced (15 mg/kg body wt once a week for 3 weeks) formation of aberrant crypt foci (ACF) were examined. The latter two preparations (2.5% in the diet) significantly inhibited ACF formation (P < 0.005). In the second experiment, a long-term study of the effects of rice-germ was done. One group was treated with AOM alone, four groups received the carcinogen and were fed the diets containing 2.5% rice-germ or 2.5% GABA-enriched defatted rice-germ for 5 (initiation phase) or 30 weeks (post-initiation phase), two groups were treated with rice-germ or GABA-enriched defatted rice-germ alone and one group was kept on the basal diet. At the termination of the study, dietary exposure to rice-germ during the initiation phase significantly reduced the incidence of colonic adenocarcinoma (71 versus 29%, P < 0.01). GABA-enriched defatted rice-germ or rice-germ during the post-initiation phase also decreased the frequency of colonic adenocarcinoma (71 versus 20%, GABA-enriched defatted rice-germ feeding, P < 0.01; 27%, rice-germ feeding, P < 0.01). These data suggest that constituents of rice-germ are possible dietary preventatives for human colon cancers.

Animals↗

PubMed1999

Localization of the Ca(2+)-binding protein, Bra r 1, in anthers and pollen tubes.

Calcium plays an essential role during pollen development and pollen tube growth, and several Ca(2+)-binding proteins are expressed in anthers. We have previously reported that Brassica pollen allergens encoded by Bra r 1 and Bra r 2 show sequence similarities to Ca(2+)-binding proteins [Toriyama et al. (1995) Plant Mol. Biol. 29: 1157]. Herein, we report that both genes are expressed in the diploid tapetum and haploid microspores, as detected by in situ RNA hybridization. Immunoblot analysis revealed that Bra r 1 and Bra r 2 were accumulated in anthers during pollen development. When pollen grains were suspended in an aqueous solution, both proteins were mainly detected in the pollen extracellular fraction, indicating that Bra r 1 and Bra r 2 are released from the pollen upon hydration. Localization of Bra r 1 was further investigated in sections of anthers and pollen tubes. Bra r 1 was detected in the tapetum, microspores and pollen grains. In longitudinal sections of cross-pollinated pistils. Bra r 1 was detected throughout pollen tubes elongating in transmitting-tissue. These findings suggest that Bra r 1 may be involved in pollen-pistil interaction and pollen tube growth.

Allergens↗

PubMed1999

Specific lipid-protein interactions in a novel honeycomb lattice structure of bacteriorhodopsin.

In the purple membrane of Halobacterium salinarium, bacteriorhodopsin trimers are arranged in a hexagonal lattice. When purple membrane sheets are incubated at high temperature with neutral detergent, membrane vesicularization takes place, yielding inside-out vesicles with a diameter of 50 nm. The vesicular structure becomes unstable at low temperature, where successive fusion of the vesicles yields a crystal which is composed of stacked planar membranes. X-ray crystallographic analysis reveals that the bacteriorhodopsin trimers are arranged in a honeycomb lattice in each membrane layer and that neighbouring membranes orient in opposite directions. The native structure of the trimeric unit is preserved in the honeycomb lattice, irrespective of alterations in the in-plane orientation of the trimer. One phospholipid tightly bound to a crevice between monomers in the trimeric unit is suggested to act as a glue in the formation of the trimer.

Bacteriorhodopsins↗

PubMed1999

[A new exanthematous disease in newborn infants caused by exotoxins producing Staphylococcus aureus; exotoxins production of the isolates and serum levels of antitoxin antibody in the patients and umbilical cord blood].

Recently, in Japan newly neonatal exanthematous disease was elucidated to be caused by staphyloccocal supcrantigcnic exotoxins, mainly TSST-1. We studied exotoxins producibility of 43 strains of S. aureus isolated from neonates with exanthematous disease and examined antibody titers to staphylococcal enterotoxin A, B, C (SEA, SEB, SEC) and toxic shock syndrome toxin 1 (TSST-1) of the patients and control (umbilical cord blood from term infants). The results were as follows 1.34 of 43 strains (79%) isolated from the patients were SEC and TSST-1 producing MRSA, 5 strains (12%) were SEB, SEC, and TSST-1 producing MRSA, 1 strain (2%) was SEB and TSST-1 producing MRSA, 2 strains (12%) were SEB producing MSSA and did not produce TSST-1. The 1 strain (2%) was MSSA which produced SEC and TSST-1. 2. 16 neonates with exanthematous disease, who showed typical clinical signs and laboratry findings of thrombocytopenia, with SEC and TSST-1 producing MRSA isolates had significantly low anti-TSST-1 antibody titers at onset (p < 0.05), compared with the control (umbilical cord blood from term infants): TSST-1 appeared to the causative agent for the disease. In two neonates with exanthematous disease, with SEB- and non- TSST-1-producing MSSA isolates, anti-SEB antibody titers were low at onset, so SEB appeared to the causative agent for the disease. 3. In Japan, low anti-TSST-1 antibody titers were found in the umbilical blood samples from about 70% of term infants; and low anti-SEB or anti-SEC antibody titers were found in samples from only about 10% of them, that is, a number of term infants had anti-SEB and anti-SEC antibodies. The majority of S. aureus isolated from neonates with exanthematous disease were enterotoxin- and TSST-1-producing MRSAs. The results of our study by measuring antitoxin antibody titers suggested that SEB and SEC might not be pathogenically responsible, but TSST-1 was considered to be responsible for the majority of exanthematous disease. Prevalence of TSST-1-producing MRSA in the neonatal and premature baby ward is the main cause for the high incidence of this disease in Japan, whereas the low antibody titer to TSST-1 in the mother, in comparison with the anti-enterotoxin antibody titers, may also be a predisposing factor.

Antibodies, Bacterial↗

PubMed1999

The strength of interaction at the Raf cysteine-rich domain is a critical determinant of response of Raf to Ras family small GTPases.

To be fully activated at the plasma membrane, Raf-1 must establish two distinct modes of interactions with Ras, one through its Ras-binding domain and the other through its cysteine-rich domain (CRD). The Ras homologue Rap1A is incapable of activating Raf-1 and even antagonizes Ras-dependent activation of Raf-1. We proposed previously that this property of Rap1A may be attributable to its greatly enhanced interaction with Raf-1 CRD compared to Ras. On the other hand, B-Raf, another Raf family member, is activatable by both Ras and Rap1A. When interactions with Ras and Rap1A were measured, B-Raf CRD did not exhibit the enhanced interaction with Rap1A, suggesting that the strength of interaction at CRDs may account for the differential action of Rap1A on Raf-1 and B-Raf. The importance of the interaction at the CRD is further supported by a domain-shuffling experiment between Raf-1 and B-Raf, which clearly indicated that the nature of CRD determines the specificity of response to Rap1A: Raf-1, whose CRD is replaced by B-Raf CRD, became activatable by Rap1A, whereas B-Raf, whose CRD is replaced by Raf-1 CRD, lost its response to Rap1A. Finally, a B-Raf CRD mutant whose interaction with Rap1A is selectively enhanced was isolated and found to possess the double mutation K252E/M278T. B-Raf carrying this mutation was not activated by Rap1A but retained its response to Ras. These results indicate that the strength of interaction with Ras and Rap1A at its CRD may be a critical determinant of regulation of the Raf kinase activity by the Ras family small GTPases.

Animals↗

PubMed1999

[Receptor-activated Ca2+ influx: capacitative Ca2+ entry and TRP proteins].

Receptor-activated Ca2+ channels (RACC) are triggered in response to activation of G protein-coupled receptors or tyrosine kinase-coupled receptors. RACCs, together with voltage-dependent Ca2+ channels, form physiologically the most important Ca2+ influx pathways, being highly diverged in activation mechanisms and Ca2+ permeability. Characterization of mammalian homologues of Drosophila TRP proteins has been an important clue for understanding molecular mechanisms underlying receptor-activated Ca2+ influx in vertebrate cells. Recent issues have been whether any members of the TRP family form capacitative Ca2+ entry (CCE) channels activated by release of Ca2+ from internal stores and their depletion. We have isolated cDNAs that encode seven mouse TRP homologues, TRP1-7. TRP homologues are distributed differently among tissues, although they are all abundant in the brain. Functional characterization of TRP proteins recombinantly expressed in HEK cells indicate that TRP5 is highly permeable to Ca2+, while TRP3 and 7 are non-selective cation channels. The results demonstrate that TRP3,5,7 are capable of generating Ca2+ currents after desensitization of the stimulated G-protein-coupled receptors and replenishment of stores, suggesting that store depletion is not necessary to maintain activity of the TRP homologues. Ca2+ positively regulates TRP channels through Ca(2+)-calmodulin pathways, but via different Ca(2+)-calmodulin-dependent enzymes. Thus, activation of TRP channels is not tightly coupled with store depletion as CCE, suggesting that CCE (or CRAC) channels are molecular entities separate from TRP.

Animals↗

PubMed1999

Cell death of uterine natural killer cells in murine placenta during placentation and preterm periods.

In the murine uterus granulated metrial gland (GMG) cells appear only during normal pregnancy. GMG cells belong to a member of natural killer (NK) cells and play an important role in fetus survival and placental growth. Our previous study revealed that mouse GMG/uterine NK (uNK) cells in the late pregnancy rapidly disappear from the uterus, due to the degenerative change classified as necrosis. But there are few reports regarding appearance and morphology of uNK cells during late pregnancy. We examined histologically and histochemically how and when uNK cells undergo cell death. The uNK cells in the metrial gland increased in number and reached maximum until day 12 of pregnancy. Sudden disappearance, however, occurred after day 15 and the granules reduced in both number and size. In situ DNA fragmentation detection revealed that DNA fragmented uNK cells increased in number during days 13 to 15 and reached 70.2% at day 15 of pregnancy. From days 13 to 17, uNK cells were positive against anti-perforin antibody. Ultrastructurally, uNK cells at day 15 showed poor organelles and unusual granules in structure. In uNK cells at day 17, condensation of nucleus chromatin, reduction in size and phagocytosis into other uNK cells were observed. These results suggested that uNK cells undergo at least two types of cell death, classified as necrosis and apoptosis, at the different stages of pregnancy, and that perforin is not a mediator for cell death.

Animals↗

PubMed1999

Quantitative changes of lung tissue components during perinatal period in rats.

Quantitative changes of lung tissue components (air spaces lined by PAS-positive and PAS-negative epithelium, blood vessels and interstitium) were investigated in developing rats from fetal day 18 through neonatal day 1. The volume of the left lung increased significantly from fetal day 18 through neonatal day 1. The percentage and volume of the air spaces increased strikingly between fetal days 20 and 21. However, the percentage of the air spaces lined by PAS-positive epithelium decreased significantly from fetal days 20 to 21, and that of the spaces lined by PAS-negative epithelium increased between the two days. The proliferating cell nuclear antigen (PCNA)-positive cells were rich in the interstitium and epithelium of the air spaces on fetal days 18 and 19. The percentage of the interstitium decreased significantly from fetal day 18 through neonatal day 1, showing remarkable decrease between fetal days 20 and 21. From fetal day 20 onward, the PCNA-positive cells decreased in number and located in the epithelium of the conducting air ways and interstitium. Based upon these findings, the present study suggests that the period from fetal days 20 to 21 is a critical time for the development of fetal lung: the period before fetal day 20 is that for proliferation and the period after fetal day 21, functional differentiation of the lung.

Animals↗

PubMed1999

Uterine NK cells produce epidermal growth factor in the murine pregnant uterus.

Uterine natural killer (uNK) cells belong to the large granular lymphocytes in the murine pregnant uterus and play essential roles in pregnancy success. We defined whether uNK cells can produce epidermal growth factor (EGF) important for implantation and embryo growth. The uNK cells were immunohistochemically positive for anti-EGF antibody especially during days 6 to 9 and at day 15 of pregnancy. Immunoreaction for EGF receptor was observed on the stromal cells in the metrial gland and trophoblasts in the placental labyrinth. EGF secretion (72.1 +/- 2.25 ng/10(40 cells) was noted in cultured uNK cells isolated from the metrial gland at day 15 of pregnancy. Treatment of anti-asialo-GM I antibody raised the level of EGF (129 +/- 21.5 ng/10(4) cells). These results suggest uNK cell can produce and release EGF for placental development.

Animals↗

PubMed1999

[A case of myelodysplastic syndrome associated with IgA nephropathy].

A 72-year-old man was admitted for examination of dyspnea and pitting edema of the lower legs in July, 1996. His hemoglobin level was 6.9 g/dl, and myelodysplastic syndrome (MDS) was revealed by bone marrow aspiration, and frequent transfusions were needed. His renal function rapidly deteriorated in the middle of August (BUN 45 mg/dl, Cr 4.8 mg/dl) and IgA nephropathy (IgAN) with marked intestinal nephritis was disclosed by renal biopsy. In November, joint manifestations of warmth and pain, which suggested arthritis, appeared at the bilateral wrist and ankle joints. Soon after receiving prednisolone (20 mg/day), the arthritis was relieved. Renal function also improved (BUN 41 mg/dl, Cr 21 mg/dl) and frequent transfusions were no longer necessary. This is a case with various clinical manifestations of MDS, IgAN, and arthritis, and appears to be the first MDS case complicated with IgAN. A number of case reports have identified immune abnormalities in patients with MDS. Immune and bone marrow abnormalities have been reported to be involved in the pathogenesis of IgAN. Thus, MDS could be complicated by IgAN. Their pathogenetic association is discussed in this paper.

Aged↗

PubMed1999

[Clinical retrospective study on outpatients at clinic for oral implant].

A retrospective study was made on 1,000 outpatients visiting the Clinic for Oral Implant, University Hospital, Faculty of Dentistry, Tokyo Medical and Dental University between April 1995 and June 1998. The following findings were obtained according to sex, age group, reason for visit, classification of edentulous area, indication and contraindication for implant therapy, and pre-implant surgical treatment. Forty percent of the outpatients were male and 60% were female. The largest number was in the 50-59-year-old group. The reason for visit of 822 patients was request for implant therapy. 123 patients with uncomfortable implants done at other clinics, 12 patients undergoing maintenance of implants at other clinics and 43 other patients. There were 505 upper jaw cases and 529 lower jaw cases. Most anterior edentulous cases were in the upper jaw group. Most of the posterior edentulous cases were unilateral cases and many of them were free-end saddle cases. Indication patients were 447 of the 822 outpatients. The main contraindication was insufficient volume of bone. Two hundred twenty-one of the 477 indication patients did not need the pretreatment which consisted of extraction, bone graft, free gingival graft, provisional prosthetics, sinus lift, and so on.

Adult↗

PubMed1999

[Pulmonary metastatic malignant phyllodes tumor showing multiple thin walled cavities].

A 52-year-old woman who had undergone a partial mastectomy 1 year earlier because of benign phyllodes tumor was admitted because of dry cough and abnormal chest radiograph findings. Chest computed tomograms demonstrated multiple thin-walled cavities and nodules. Clinical examinations and transbronchial biopsy specimens failed to provide a conclusive diagnosis. However, the pulmonary thin-walled cavities enlarged, and a nodular shadow revealed cavitary formation. An open lung biopsy was performed to diagnose the pulmonary lesions. Although biopsy specimens disclosed the infiltration of poorly differentiated adenocarcinoma cells in pleura and pulmonary parenchyma, no primary site was detected. The patient did not respond to systemic chemotherapy (CDDP and VP-16), and died of respiratory failure due to advanced pulmonary metastasis. Autopsy demonstrated marked tumor invasion of the lungs, myocardium, and bone. We analyzed malignant cells in lung tissues at autopsy by immunohistochemistry, and found identical malignant cells in surgical samples obtained during the patients earlier mastectomy. A diagnosis of pulmonary metastasis from malignant phyllodes tumor of the breast was made. Thin walled cavitary lesions from malignant phyllodes tumor are rare; however, pulmonary metastasis of malignant phyllodes tumor should be considered one disease that exhibits thin-walled cavities as a radiographic manifestation.

Adenocarcinoma↗

PubMed1999

[Two cases of hearing disorder following general anesthesia].

Hearing impairment is not often considered as a potential complication of general anesthesia, despite several reports of post-operative sensorineural hearing loss. These disorders have occurred after otological as well as cardiobypass surgery. We experienced two patients both of whom had undergone orthopedic surgery. In both cases the patients experienced bilateral reversible hearing impairment after general anesthesia with nitrous oxide. It is likely that a change in the middle ear pressure as a result of Eustachian tube dysfunction may have caused transient conductive hearing loss added to sensorineural hearing disorder. After these cases we interviewed a series of 115 patients who had undergone general anesthesia to assess the extent of this problem. Contrary to our expectation, 7 patients complained of ear fullness or autophony after inhalation of nitrous oxide, although these symptons diminished within 24 hours. It is important to be aware of the possibility of hearing impairment when nitrous oxide is used especially if the patient has a history of a previous middle ear disease.

Aged↗