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Biomedical subjects

Y Oku

Publications and source records attributed to Y Oku.

At least 55 records · Page 3Linked to original sources
PubMed1998

Monitoring of Echinococcus multilocularis infection in red foxes in Shiretoko, Japan, by coproantigen detection.

The study was conducted to evaluate a mAb-based coproantigen detection assay for monitoring fox prevalence of Echinococcus multilocularis infections in the Shiretoko National Park in Hokkaido, Japan. Eight fox families, each consisting of 2-4 adults and their pups, were selected because their territories have been determined. Faeces of each family (total n = 537) were collected monthly from April to October, 1994. Detection of coproantigen and taeniid eggs was recognized in 58 and 27 faeces, respectively, but mostly restricted in 1 family, in which coproantigen ELISA OD values had dual peaks, one in June and the other in October, whereas taeniid eggs were detected only from April to July. Fox pup faeces (n = 51) collected around the dens used by the positive family were all coproantigen and taeniid egg negative except for 1 faeces. These results suggest that the prevalence and infection pressure in the study area were low and the infected family terminated the infection in the summer and acquired a new one in the early autumn, 1994. This monitoring method for fox infection will be a practical management tool for E. multilocularis infection, especially at the tourist spots in Hokkaido where close contact of fox with humans is frequently observed.

Animals↗
PubMed1998

Deep breathing and awake apnoea in a patient who had recurrent hypoxaemia and hypercapnia without sleep apnoea.

A 21 yr old with deep breathing and awake apnoea, who had recurrent hypoxaemia and hypercapnia without sleep apnoea, was presented. Although the organic abnormality responsible for the breathing disturbance was not found, administration of acetazolamide facilitated several breaths between sighs, and the patient's hypoxaemia with hypercapnia improved. Some patients who have abnormalities in the cortical control of breathing that cannot be detected by present methods of examination may experience some improvement in breathing with the administration of chemical stimulants such as acetazolamide.

Acetazolamide↗
PubMed1998

Coproantigen detection in a survey of Echinococcus multilocularis infection among red foxes, Vulpes vulpes schrencki, in Hokkaido, Japan.

Detection of Echinococcus coproantigen using sandwich enzyme-linked immunosorbent assay (sELISA) was performed on fecal samples of red foxes in Hokkaido, Japan. Fecal samples were collected around fox dens in 1990 and 1992. The antibodies used for sELISA recognize heat-resistant antigens, thus all fecal samples were heated to render it safe for handling before examination. Detection of taeniid egg in fox feces collected was considered as an indication of E. multilocularis infection. In fecal samples collected in 1990 and 1992, coproantigen positive results out of taeniid-egg positive cases were 38/40 (95.0%) and 95/97 (97.9%), respectively. In addition, coproantigen was detected regardless of fecal condition when collected from the field, suggesting that the antigens detected by this method are quite stable. These results suggest that detection of coproantigen is useful for field surveys of foxes naturally infected with E. multilocularis.

Animals↗
PubMed1997

Coproantigen detection in dogs experimentally and naturally infected with Echinococcus granulosus by a monoclonal antibody-based enzyme-linked immunosorbent assay.

A sandwich ELISA for the detection of Echinococcus granulosus coproantigen in formalin and heat-treated faecal supernatants of dogs was developed. The assay used affinity-purified polyclonal antibodies obtained from rabbits hyperimmunised with E. granulosus excretory/secretory antigens and biotinylated monoclonal antibody EmA9 produced against adult E. multilocularis somatic extract. The test was sensitive to 7 ng and 2.3 ng of E. granulosus protein and carbohydrate/ml of faecal supernatant, respectively. Thirteen helminth-free dogs were infected with different amounts of E. granulosus protoscoleces and the presence of coproantigen was monitored during the prepatent period until day 35 post-infection, when they were necropsied. Faecal antigen levels started to rise above the normal range between days 10 and 20 post-infection, and typically peaked at the end of the experiment. All the dogs, bearing from 3 to 67,700 worms, showed positive values in the ELISA during the prepatent period. One dog experimentally infected with Taenia hydatigena metacestode and harbouring three worms, tested positive only after the prepatent period at day 52. The test was applied to 98 stray dogs. The ELISA detected all of four dogs naturally infected with E. granulosus, two dogs with patent infections of T. hydatigena and two dogs with no cestode infections, showing a sensitivity of 100% and a specificity of 96%.

Animals↗
PubMed1997

The effect of the level of ventilatory assist on the level of respiratory drive in decerebrate cats.

The present study was undertaken to investigate whether, independent of changes in PaCO2, ventilatory assist influences not only the pattern but also the level of the respiratory drive. The experiments were performed on decerebrate and paralyzed cats ventilated by a phrenic-driven servo respirator at three different FICO2 levels (0, 0.30, 0.05). The level of ventilatory assist was altered within the range where PaCO2 did not exceed 80 Torr. A higher FICO2 accompanied a higher level of ventilatory assist. The relationship between the minute phrenic activity and log10 PaCO2 at a given FICO2 was linear. No significant difference was found in the regression lines at different levels of FICO2. We conclude that ventilatory assist has little effect on the respiratory drive at a constant level of chemical feedback during hypercapnia.

Animals↗
PubMed1997

Role of host immune response in the occurrence of gastropathy in rats infected with larval Taenia taeniaeformis.

Decrease of spleen weight from peak to control levels together with a corresponding decline of serum IgG level at the onset of gastric hyperplasia in Taenia taeniaeformis-infected euthymic rats, may indicate that a form of down regulation of host immune response during the course of larval T. taeniaeformis infection could facilitate the occurrence of gastropathy in rats. Gastric hyperplasia developed in T. taeniaeformis-infected athymic nude rats, indicating that occurrence of gastropathy associated with larval T. taeniaeformis infection in the rat is T cell independent. Apparently, gastric hyperplasia appeared early in nude rats which suggests that absence of T cell-mediated response could have facilitated its early occurrence.

Animals↗
PubMed1997

Hypoxic ventilatory response and breathlessness following hypocapnic and isocapnic hyperventilation.

STUDY OBJECTIVES: To investigate the etiology of posthyperventilation (post-HV) hypoxemia following voluntary hyperventilation (VHV), we examined the effects of hypocapnic (hypo-CO2) and isocapnic (iso-CO2) VHV on the hypoxic ventilatory response (O2-response) and on the sensation of breathlessness during the O2-response. METHODS: O2-responses and visual analog scale (VAS) scores for estimating breathlessness in 10 normal subjects during the O2-response under iso-CO2 conditions and under hypo-CO2 conditions immediately following voluntary maximal HV of 3 min duration were examined. RESULTS: Although there was no significant difference in the post-HV ventilation levels following hypo-CO2 vs iso-CO2 VHV, the VAS scores at the start of the O2-response following hypo-CO2 VHV (30.2+/-24.2 mm) were significantly higher (p<0.05) than the VAS scores at the start of the O2-response following iso-CO2 VHV (13.7+/-8.4 mm). However, VHV did not have a significant effect on the O2-response at 2 min after the VHV when the arterial O2 saturation (SaO2) was below 90%. The nonsteady-state hypo-CO2 induced by VHV greatly attenuated the O2-response below 90% SaO2 and VAS scores at 70% SaO2. CONCLUSIONS: Elevated VAS scores immediately following the hypo-CO2 VHV, which might be independent of actual breathing levels, and the attenuation of the O2-response following the hypo-CO2 VHV were not due to input from lung and chest wall mechanoreceptors induced by the hyperpnea itself, but rather to the hypo-CO2 induced by hyperpnea.

Adult↗
PubMed1997

Ventilatory responses and subjective sensations during arm exercise and hypercapnia in patients with lower-cervical and upper-thoracic spinal cord injuries.

We measured the ventilatory responses and subjective sensations during arm exercise in patients with lower cervical and upper thoracic spinal cord injuries in order to evaluate the effects of chest wall deafferentation on these responses. Visual analog scales with verbal descriptors were used to quantify respiratory sensations of different affectional qualities. Patients as well as normal subjects reported stronger respiratory sensations upon CO2 rebreathing as compared to during arm exercise with an equivalent minute ventilation (p<0.05). There were no qualitative nor quantitative differences in the respiratory sensations during CO2 rebreathing between the patients and normal subjects. However, patients with spinal cord injuries showed a higher minute ventilation and a lower end-tidal PCO2 during incremental arm exercises (p<0.01), and thus tended to hyperventilate. We conclude that chest wall afferent denervation does not contribute significantly to the perception of breathlessness in patients with spinal cord injuries.

Adult↗
PubMed1997

Effects of resistive load on the phase difference between chest and mouth flow in patients with chronic obstructive pulmonary disease.

The influence of the resistive load on the phase difference (PD) between chest wall and mouth flow in patients with chronic obstructive pulmonary disease (COPD) was investigated, and the factors that induce an enlargement of the PD were assessed. After a resistance tube (R = 2.8 hPa/l/s) was applied to the mouth of the subjects, the PDs increased significantly both in normal (pre: 2.20 +/- 0.89, post: 5.60 +/- 2.04, P < 0.01) and in COPD (pre: 10.86 +/- 3.81; post: 13.12 +/- 3.64, P < 0.01). A significant correlation between the airway resistance and PD was noted (r = 0.730, P < 0.001). These results suggest that airway resistance is an important determinant for the PD. The predicted phase difference (PD') was then calculated by the Runge-Kutta method, using the measured chest flow, the time domain functions of airway resistance and the thoracic gas volume during a respiratory cycle, assuming that the respiratory system was a single compartment. The PD/PD' at pre-resistive load was significantly larger in COPD than in normal subjects (normal: 1.03 +/- 0.11; COPD, 1.45 +/- 0.19, P < 0.01), whereas the PD/PD' at a post-resistive load was significantly smaller than at the pre-resistive load in COPD patients. These results agree well with the two parallel or serial compartment model with inhomogeneous airway resistance, where the mechanical property of the partitioning tissue between the two compartments was taken into account. The pattern of the increase in the work energy consumed within the airway lumen calculated from this model was almost the same as for PD. Thus, we conclude that the PD may be a good index of the overload of the respiratory movement and available to predict muscle fatigue in COPD patients.

Adult↗
PubMed1997

Quantitative assessment of the spatial distribution of low attenuation areas on X-ray CT using texture analysis in patients with chronic pulmonary emphysema.

An automated and quantitative assessment of the spatial distribution of low attenuation areas (LAA) on X-ray CT was performed using texture analysis in chronic pulmonary emphysema (CPE) patients. LAA was defined as those areas having a density less than the mean minus one SD of the control (-960 HU). The probability of change from non-LAA to LAA between a given pair of pixels with horizontal intervals of i pixels (RNi) was evaluated, because this reflects the interaction between LAA and non-LAA regions with different resolutions. The relationship between the percentage area of the LAA over the total area of the entire lung field (LAA%) was subsequently estimated. The RNi increased sharply as the i value increased from 1 to 5, but then almost became a plateau for i values larger than 5. This suggests that the fundamental structures in the LAA areas ranged from 1 x 1 to 5 x 5 pixels in size. RN1-LAA% and RN5-LAA% plots produced curves which were convex, with peak values at approximately 50 LAA% of 0.09 and 0.18, respectively. In the RN5/RN1-LAA% plot, the RN5/RN1 ratio remained constant at 2.0 regardless of the LAA%. A random process simulation was performed to determine the patterns of LAA proliferation if the spatial distribution of the LAA units was random. When the unit size was kept constant, the results of the simulation did not fit the empirical relationship between the LAA% and the three parameters (RN1, RN5 and RN5/RN1). The simulation provided the best-fitting curves when the unit size of the LAA increased in proportion with the LAA%, starting from a 1 x 1 pixel size increasing at a ratio 1 x 1/(5 LAA%). This suggested that the LAA units do not proliferate randomly in spatial orientation at a fixed unit size, but rather spread throughout the whole lung field in a congregated form whilst increasing their unit size. Thus, it may be concluded that healthy lung tissues near emphysematous lesions have a high probability of suffering from emphysema in the future. This may be due to a direct effect of the neighboring emphysematous lesion or due to a pathologic change in the larger bronchii which dominate both the healthy tissues and the emphysematous lesions.

Aged↗
PubMed1997

Standardization of low attenuation area versus total lung area in chest X-ray CT as an indicator of chronic pulmonary emphysema.

We examined the methods for measuring the LAA% (100 x low attenuation area/total lung area) on thoracic X-ray CT scans in order to develop a useful indicator of chronic pulmonary emphysema (CPE). First, we modified the method for calculating the LAA% to be applicable by the programming tool installed in a commercially available CT machine in order to minimize manual procedures. This new method proved to be applicable in all CT machines produced after 1987. Second, we examined the difference in the Hounsfield Unit (HU) between different CT machines using two kinds of phantoms. One phantom was composed of Styrofoam, which has a density similar to the low attenuation areas. The other phantom was composed of Styrofoam and water, which has a density similar to the lung. We proved that the difference of LAA% with the correct value was 5% at maximum among four different CT machines. Thus, the phantom developed in the present study may play an important role in the standardization of HU. Finally, the possibility of decreasing the X-ray levels was examined. Twenty-five percent of the standard electrical current provided the same LAA% in cases where the subject was an established CPE patient, whereas the LAA% was overestimated in subjects with a normal LAA% value. However, a correction using a linear regression equation may be possible in the latter cases. It may be concluded that LAA% analysis can easily be performed in many city hospital, without much investment of manual procedures or any corrections to the HU levels between different CT machines. This method may be useful as a routine follow up for CPE patients because of the smaller irradiated dose given when using a CT machine.

Algorithms↗
PubMed1997

Effect of ultraviolet radiation on the infectivity of Taenia taeniaeformis eggs.

The effect of ultraviolet (UV) radiation on the infectivity of Taenia taeniaeformis eggs was observed. The eggs were exposed to various UV doses and orally inoculated to rats. The number of cysts and lesions decreased dose-dependently, and neither cyst nor lesion was observed from rats infected with eggs exposed to a total dose of 2,880 mJ/cm2 or more. For evaluation of protective role of embryophore against UV radiation, the onchospheres with/without embryophore were exposed to UV radiation. Remarkably lower numbers of cyst and lesions were observed in rats inoculated with eggs which were exposed to a total dose of 30 mJ/cm2 or more after removal of embryophore. These results suggested an importance of the protective function of the embryophore in the protection against UV radiation.

Animals↗
PubMed1996

Effects of changes in ventilation on respiratory discomfort during isocapnic exercise.

We studied the effects of changes in the level of ventilation on respiratory discomfort during isocapnic exercise. Six subjects exercised at 60 W on a cycle ergometer. They initially breathed 2.5% CO2 in oxygen for 75 breaths. Ventilatory parameters of the last 10 breaths were used as controls. In 7 subsequent test sessions each lasting 2 min alternating with 2 min free breathing periods, subjects tried to achieve a target ventilation ranging from 0.7 to 1.3 times the control with a visual feedback system. End-tidal CO2 was regulated automatically at the control level by changing the inspired CO2. Breathing discomfort was measured at the end of each session using a visual analog scale. Isocapnic constraining of ventilation (0.7 times the control) during exercise significantly increased respiratory discomfort (p < 0.05). Increases in ventilation had no significant effect. These results indicate that respiratory discomfort during exercise is exaggerated when the level of ventilation falls below that spontaneously adopted even when chemical drives are held constant.

Adult↗
PubMed1996

Time course of coproantigen excretion in Echinococcus multilocularis infections in foxes and an alternative definitive host, golden hamsters.

Coproantigen excretion during experimental infections of Echinococcus multilocularis in foxes and an alternative definitive host, golden hamsters, was evaluated by a sandwich ELISA using a monoclonal antibody. A sigmoidal increase of antigen excretion from the developing parasites was observed in in vitro incubation of the parasites collected on different days during the first 21 days post-infection (DPI). In hamsters, the ELISA O.D. value of faeces became positive at 4 DPI. Thereafter, the O.D. value increased in semi-sigmoidal fashion in the first 42 DPI, probably reflecting the development of the parasites. In foxes, the O.D. value became positive at 6 DPI. However, contrary to that in hamsters, after the initial steep rise, the O.D. value suddenly decreased to 1/2 the level during 15-17 DPI, indicating that a large number of worms might have been expelled. The parasite eggs were detected by the sugar centrifugal-flotation technique (Ito, Yagi & Ishige, 1989) from 29 to 84 DPI but not thereafter to 125 DPI, although mature parasites were detected at 125 DPI. In contrast, positive O.D. values were obtained almost constantly until 125 DPI, indicating that the coproantigen detection assay was more sensitive than the egg detection assay. The detection limit of the coproantigen assay was roughly estimated to be around 100 worms. These observations, along with the fact that the assay was designed to detect a heat-resistant coproantigen in heat-sterilized fecal samples, indicate that the coproantigen detection assay is a safe and useful method, not only for diagnosis in the definitive host of E. multilocularis, but also for monitoring parasite development and change in parasite burden during an experimental infection.

Animals↗
PubMed1996

High prevalence of Ancylostoma spp. infection in dogs, associated with endemic focus of human cutaneous larva migrans, in Tacuarembo, Uruguay.

A helminthological survey of the intestinal parasites in stray dogs was conducted in urban and suburban area of Tacuarembó, Uruguay, during winter time. Eighty stray dogs captured in the city were necropsied. Seventy nine dogs (98.8%) were positive for helminth infection. Seventy seven (96.3%) were parasitized by hookworms. Two species of hookworms were found: Ancylostoma caninum 96.3% and A. braziliense 49.4%. This is the first report of the prevalence of A. braziliense in Uruguay. Considering that incidences of human cutaneous larva migrans caused by the migration of hookworms larvae were restricted mainly to the northern part of Uruguay and that only A. caninum were reported to be prevalent in the southern part, it is supposed that A. braziliense is the primary causative agent of human cutaneous larva migrans in Uruguay.

Ancylostoma↗
PubMed1996

Typing of verotoxins by DNA colony hybridization with poly- and oligonucleotide probes, a bead-enzyme-linked immunosorbent assay, and polymerase chain reaction.

To identify the type of Verotoxins (VT) produced by Verocytotoxin-producing Escherichia coli (VTEC), a sensitive bead-enzyme-linked immunosorbent assay and polymerase chain reaction with common and specific primers to various VTs (VT1, VT2, VT2vha, VT2vhb, and VT2vp1) were developed. Together with colony hybridization tests with oligo- and polynucleotide probes, these methods were applied to VTEC isolates to type the VT produced. The toxin types of 26 of 37 strains were identified, but the reaction profiles in assays of the remaining 11 strains suggested the existence of new VT2 variants. The application of these identification procedures may be useful as a tool for clinical and epidemiological studies of VTEC infection.

Animals↗
PubMed1996

Effects of willful ventilatory control on respiratory sensation during hypercapnia.

Remarkable augmentation of breathing discomfort has been noted when ventilation is constrained to the steady state level during progressive hypercapnia. However, the effect of willful enhancement of ventilation on breathing discomfort remains to be evaluated. The present study examined the effects of moderate willful increases or decreases in ventilation during progressive hypercapnia on breathing discomfort in 12 subjects. There were a total of 5 rebreathing trials. In the first (F1) and the fifth trials the subjects rebreathed freely. In the other trials subjects breathed by tracking a target to achieve hypercapnic ventilatory responses that were the same (HCVR-S), 25% higher (HCVR-H) and 25% lower (HCVR-L) than in the F1 trial. Breathing discomfort was assessed every 30 s by a 150-mm visual analog scale (VAS). The sensational response (dVAS/dPCO2) during HCVR-S [3.8 +/- (SE) 0.8 mm/Torr] was significantly smaller (p < 0.01) than that during the F1 (6.3 +/- 0.8 mm/Torr) trial. HCVR-H resulted in a further decrease in dVAS/dPCO2 to 3.1 +/- 0.7 mm/Torr as compared to HCVR-S (p < 0.05). HCVR-L significantly increased dVAS/dPCO2 to 4.9 +/- 0.7 mm/Torr compared to HCVR-S (p < 0.05). The final free rebreathing ventilatory response was significantly larger than the initial free rebreathing response (2.7 +/- 0.5 as compared to 2.1 +/- 0.4 liters/min/Torr, p < 0.01). However, the sensational response did not change (6.3 +/- 0.8 vs. 5.8 +/- 0.7 mm/Torr). These rebreathing studies indicate that willful control of respiration decreases respiratory sensation even at comparable levels of ventilation. In particular, moderate willful increases in ventilation produce an ameliorating effect on the sensation of breathing discomfort.

Adult↗