Inhibitory effect of different UV lamps on the infectivity of taeniid eggs

The expanding distribution of alveolar echinococcosis in Hokkaido, Japan necessitates a search for control measures, particularly for killing Echinococcus eggs; and UV radiation is a potential tool. To determine the effective UV lamp and its optimum duration of exposure to inhibit the infectivity of taeniid eggs, three UV lamps (UVA, UVB and UVC) with peak emissions at different wavelengths were used to irradiate eggs of Taenia taeniaeformis. Irradiation was done in durations of 30, 90, 270, 810, 2,430 and 7,290 s. Infectivity of the irradiated eggs was tested by oral inoculation into rats. The inhibitory effect of the UV lamps at different exposure durations was determined by the reduction in the larval cyst establishment and by the delay of larval development. The UVC lamp (narrow peak at 254 nm) was found to be the most effective lamp at an exposure duration of more than 2,430 s (2,430 mJ/cm2), attaining 100% reduction. Also, shorter exposure durations produced a significant effect on the development of irradiated eggs in a greater percentage of small cysts (> 1 mm) among the metacestodes. Irradiation delayed the development of some cysts, as observed in histopathological sections. UVA and UVB lamps were not able to attain 100% reduction. It is concluded that the UVC lamp can be used as a tool in sterilizing taeniid eggs and is thus a promising method to control echinococcosis, although it may require a higher intensity of exposure.

Seroprevalence of Borna disease virus in domestic animals in Xinjiang, China

To investigate the animals infected with Borna disease virus (BDV) in Xinjiang, China, we examined for BDV antibodies in the sera from groups of 20 horses, sheep and cattle, and from 165 wild rodents (18 species) by ELISA and immunoblot. The serological study disclosed the presence of antibodies to both BDV-p24 and -p40 in the horses (20%) and sheep (25%), whereas no apparent positive reaction was detected either in cattle or rodents. The results suggested that BDV is prevalent in horses and sheep in the district investigated.

First report of Trichinella nativa in red foxes (Vulpes vulpes schrencki) from Otaru City, Hokkaido, Japan

Forty-three red foxes (Vulpes vulpes schrencki) and nine raccoon dogs (Nyctereutes procyonoides viverrinus) were captured in Otaru City, Hokkaido, Japan and examined by muscle digestion for the presence of Trichinella sp. larvae. Of the foxes, five (11.6%) were positive for larvae of Trichinella nativa while none of the raccoon dogs were found to be positive. This finding suggests that the red foxes are important reservoir hosts of sylvatic trichinellosis in Otaru, Hokkaido. This is the first report on Trichinella nativa in wild red foxes of Hokkaido, Japan.

Distorted trachea in patients with chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVES

We evaluated the size and configuration of the trachea in patients with chronic obstructive pulmonary disease (COPD; n = 35) on high-resolution computed tomography (HRCT) images and compared them with those of healthy volunteers (n = 24).

METHODS

Using a newly developed computed method for analyzing the digital data of HRCT, the size and configuration of the trachea were automatically evaluated.

RESULTS

The size of the trachea of the COPD subjects was the same as that of the control subjects; however, the configuration was more distorted in the COPD patients. There was no difference in the tracheal index (TI), which is the ratio of the coronal to the sagittal length, between these two groups; however, the ratio of the short to the long radius (SR/LR) was significantly smaller in the COPD group than in the control group. There was a significant correlation between SR/LR and airflow limitation as assessed by pulmonary function tests in the COPD group.

CONCLUSIONS

The SR/LR is a better index of tracheal deformity than the classical TI. This deformity is not a consequence secondary to hyperinflation or emphysematous change of the lung, because the low attenuation area of the lung was not correlated with SR/LR.

Dose dependency of prednisolone tertiary-butylacetate (PTBA) treatment on the establishment and site predilection of Echinococcus multilocularis in an alternative definitive host model using Mongolian gerbil (Meriones unguiculatus)

Mongolian gerbils (Meriones unguiculatus) were orally inoculated with 10,000 protoscoleces of Echinococcus multilocularis per head after being divided into five groups (A E). Each group was dosed with prednisolone tertiary-butylacetate (PTBA) as follows: A, 0 mg; B, 0.5 mg; C, 2 mg; D, 5 mg; and E, 10 mg/head. All animals were injected subcutaneously with control solvent or PTBA every other day from 6 days pre- to 6 days post-infection. Autopsy was performed at 7 days post-infection. Doses of PTBA and the number of worms recovered showed a positive correlation (r = 0.929, P < 0.0001). In groups A, B and C, the predilection site of the worms in the small intestine could not be determined, while in group D the worms were found more in the anterior part. In group E, the predilection site was the anterior part, followed by the middle and the posterior parts of the small intestine (Fisher's test: P < 0.01). The number of worms recovered from the anterior and the middle part of the small intestine also correlated positively with PTBA dose (anterior part: r = 0.930, P < 0.0001, middle part: r = 0.917, P < 0.0001). All groups of the PTBA-treated animals showed significant loss of weight compared to the nontreated animals (P < 0.01).

Development and sexual maturation of Echinococcus vogeli in an alternative definitive host, Mongolian gerbil (Meriones unguiculatus)

An alternative definitive host model for Echinococcus vogeli was developed using Mongolian gerbils. The animals treated with prednisolone tert-butylacetate were orally inoculated with protoscoleces of E. vogeli and the development of worms in the small intestine was observed until 50 days post infection (DPI). The parasites were recovered most frequently from the anterior part of the small intestine. The band formation (the sign of proglottisation) of the worm was observed at 7 DPI, the second proglottid and tests formation at 14 DPI, spermatozoa in seminal receptacle and cleavage of ova in uterus at 21 DPI, the hook formation of oncospheres at 28 DPI and the embryophore formation at 34 DPI. Eggs in the feces were first detected at 35 DPI. The coproantigen detection method developed for E. multilocularis could detect the E. vogeli coproantigen early in the infection, at 7 DPI during the prepatent period. Therefore, this technique could be used for the diagnosis of E. vogeli, replacing ordinary fecal egg examination.

Preliminary study of the role of red foxes in Echinococcus multilocularis transmission in the urban area of Sapporo, Japan

In order to assess the infection risk of alveolar echinococcosis among urban residents of Sapporo, the capital of Hokkaido, Japan, a survey was conducted on fox distribution in the urban area and on the prevalence of Echinococcus multilocularis among the foxes. The fox distribution, evaluated from fox footprints left on the snow in parks and woodlands, and from locations of fox carcasses recorded by the Sapporo municipality, was concentrated along the border of the urban area and in the southwestern part of the city, facing the mountain. Fox faeces were collected around active fox dens, and analysed by a coproantigen detection assay and parasite egg examination for the Echinococcus infection. Thirty-three out of 155 faeces were coproantigen positive. Coproantigen-positive faeces were collected from 11 den sites (57.9% of total den sites), and all except 1 were located in the urban fringe. A high intensity of taeniid eggs (> 100 eggs per 0.5 g) containing faeces were also collected in the 3 sites of them. Although Echinococcus infection in rodents was not observed from the necropsy of 23 rodents captured around active fox dens, arvicolid rodents, a suitable intermediate host for E. multilocularis, were captured in the urban fringe. Therefore, the urban fringe offers suitable conditions in which the life-cycle of E. multilocularis could be maintained. Prompt measures to control echinococcus infection should be taken, even in urban areas.

Metabolic coupling between glia and neurons is necessary for maintaining respiratory activity in transverse medullary slices of neonatal mouse

The respiratory rhythm is generated and regulated by a neuronal network within the lower brainstem. While the neuronal mechanisms of rhythm generation have been extensively investigated, the contribution of glial cells remains to be determined. Here we report the effect of specific blockade of the glial Krebs cycle and glutamine synthetase on the neuronal activity of the respiratory network. Application of 5 mM fluoroacetate, which selectively blocks the glial Krebs cycle, suppressed rhythmic respiratory burst activity. Substitution of either the Krebs cycle substrate isocitrate (3 mM) or glutamine (3 mM) restored rhythmic network activity. Blockade of glutamine synthetase by methionine sulfoximine (0.5 mM) suppressed rhythmic burst activity as well. Resubstitution of glutamine (3 mM) was able to restore rhythmic activity in the presence of methionine sulfoximine. This data demonstrates that the glutamate-glutamine cycle in astrocytes and their supply of glutamine to neuronal glutamatergic terminals is essential for the rhythm generation in the respiratory centre.

Dose dependency of prednisolone on the establishment of Echinococcus multilocularis infection in an alternative definitive host, Mongolian gerbil

This study revealed the dose dependency of prednisolone tertiary-butylacetate (PTBA) treatment on the establishment of Echinococcus multilocularis in the small intestine of Mongolian gerbil (Meriones unguiculatus) and that some of the physiological parameters of host were correlated with the doses of PTBA and establishment of the worm. Twenty Mongolian gerbils were divided into 5 groups, according to the doses of PTBA; 0 mg, 0.5 mg, 2 mg, 5 mg and 10 mg per head. All animals were injected intraperitoneally with PTBA every other day from 6 days before to 6 days after infection. Doses of PTBA and the number of worms recovered at 7 days post-infection showed a positive correlation (r = 0.929, P < 0.0001). The increase of total protein (TP) and the decrease of the percentage of lymphocytes in the peripheral leukocytes were dependent on doses of PTBA (TP: r = 0.811, P < 0.0001, percentage of lymphocyte: r = -0.92, P < 0.0001). The TP and the percentage of lymphocyte also correlated with the number of worms recovered (TP: r = 0.617, P = 0.0049; percentage of lymphocyte: r = -0.800, P < 0.0001).

Metabotropic glutamate receptors and blockade of glial Krebs cycle depress glycinergic synaptic currents of mouse hypoglossal motoneurons

Metabotropic glutamate receptors are known to depress synaptic transmission by inhibiting transmitter release from presynaptic nerve terminals. This study reports the effects of presynaptic metabotropic glutamate receptor activation on inhibitory synaptic transmission in hypoglossal motoneurons in brainstem slice preparations of neonatal mice. Whole-cell patch-clamp recordings were performed on hypoglossal motoneurons of 2-6-day-old mice. Monosynaptic glycinergic currents were elicited by electrical stimulation of the nucleus of Roller. Application of the specific metabotropic glutamate receptor agonists (+/-)-1-aminocyclopentane-trans-1,3,dicarboxylic acid (t-ACPD), (2S, 2'R,3'R)-2-(2',3'-dicarboxylcyclopropyl)-glycine (DCG-IV) or L-2-amino-4-phosphonobutyric acid (L-AP4) depressed stimulus-evoked glycinergic inhibitory postsynaptic currents (IPSCs) by an average of 39.5, 59.4 and 39.2%, respectively. In the presence of t-ACPD, glycinergic miniature IPSCs were reduced in frequency but not in amplitude, which is indicative of a presynaptic mechanism. A similar reduction of IPSC amplitude was observed in the presence of elevated extracellular glutamate or during application of D, L-threo-hydroxyaspartate (THA), a blocker of glutamate transport, respectively. The data suggest that uptake of glutamate, which is predominately carried out by glial cells, can prevent spill-over of glutamate and activation of metabotropic glutamate receptors. A reduction of IPSCs was also observed following application of monofluoroacetic acid, a substance acting specifically on glial cells. Our results suggest that glial regulation of extracellular glutamate uptake can prevent spill-over of glutamate, and glutamatergic depression of glycinergic inhibition in hypoglossal motoneurons.

Modulation of glycinergic synaptic current kinetics by octanol in mouse hypoglossal motoneurons

Octanol-induced changes in the kinetics of glycinergic inhibitory postsynaptic currents (IPSCs) were investigated by whole-cell recording from hypoglossal motoneurons in mouse brainstem slices. Octanol (1 mM) prolonged the decay time constants (tau(decay)) of stimulus-evoked IPSCs (e-IPSCs) by 202+/-67% (SE). The depression of e-IPSC amplitudes was dose-dependent with an EC50 of 475 microM. Octanol also reduced the amplitude and prolonged the decay time constant of glycinergic currents evoked by local pressure ejection of glycine (I(gly)). Replacement of extracellular Na+ by choline and application of the specific glycine transporter GLYT1 inhibitor, sarcosine, lengthened tau(decay) of I(gly), but did not change the decay time constants of e-IPSCs. Intracellular acidification by the weak organic acid salt sodium propionate (30 mM) reduced the e-IPSC amplitude by 22+/-9% and prolonged tau by 18+/-6%. Sodium propionate also prolonged the decay time constants of I(gly) by 28+/-11%. The observed effects on decay kinetics were much smaller than those caused by octanol. The data show that octanol prolongs the decay time course of glycinergic synaptic currents by mechanisms independent of glycine uptake or intracellular acidification. We conclude that the effects were most probably due to direct action on postsynaptic glycine receptors.

Complexity of terminal airspace geometry assessed by lung computed tomography in normal subjects and patients with chronic obstructive pulmonary disease

Increases in the low attenuation areas (LAA) of chest x-ray computed tomography images in patients with chronic obstructive pulmonary disease (COPD) have been reported to reflect the development of pathological emphysema. We examined the statistical properties of LAA clusters in COPD patients and in healthy subjects. In COPD patients, the percentage of the lung field occupied by LAAs (LAA%) ranged from 2.6 to 67.6. In contrast, LAA% was always <30% in healthy subjects. The cumulative size distribution of the LAA clusters followed a power law characterized by an exponent D. We show that D is a measure of the complexity of the terminal airspace geometry. The COPD patients with normal LAA% had significantly smaller D values than the healthy subjects, and the D values did not correlate with pulmonary function tests except for the diffusing capacity of the lung. We interpret these results by using a large elastic spring network model and find that the neighboring smaller LAA clusters tend to coalesce and form larger clusters as the weak elastic fibers separating them break under tension. This process leaves LAA% unchanged whereas it decreases the number of small clusters and increases the number of large clusters, which results in a reduction in D similar to that observed in early emphysema patients. These findings suggest that D is a sensitive and powerful parameter for the detection of the terminal airspace enlargement that occurs in early emphysema.

Coproantigen survey for Echinococcus multilocularis prevalence of red foxes in Hokkaido, Japan

An epidemiological survey was conducted on the seasonal variation of Echinococcus multilocularis prevalence in red foxes from 1997 to 1998, using a monoclonal antibody-based detection of the tapeworm coproantigen. Thirty-six breeding dens of reproductive fox families were identified in the endemic area of Koshimizu, eastern Hokkaido, Japan. Fecal samples from each site were examined by coproantigen detection assay and fecal egg examination. Whereas the prevalence of coproantigen positive feces showed no seasonal fluctuation (51.6-66.7%), variation was found in the prevalence of egg positive feces in which a higher prevalence was observed in the summer and winter (31.1 and 38.7%) than spring and autumn (13.3 and 13.5%). Significant differences were observed between juveniles and adult foxes in both examinations. Samples from juvenile foxes gave higher coproantigen positive results and taeniid egg intensity. Those results suggest more juveniles infected with the cestode than adults in the same period. The practical use of coproantigen assay as a survey tool and factors which affect the prevalence and host age-related difference are discussed.

Rapid infusion of high-dose methotrexate resulting in enhanced penetration into cerebrospinal fluid and intensified tumor response in primary central nervous system lymphomas

OBJECT

Twenty-nine nonimmunocompromised patients with primary central nervous system (CNS) lymphoma were treated with high-dose methotrexate (MTX) therapy followed by irradiation. The authors investigated the correlation of infusion schedules with MTX penetration into cerebrospinal fluid (CSF), tumor response, and survival to develop a regimen that would lead to better clinical results.

METHODS

In this study, 100 mg/kg MTX was administered on either a rapid (3-hour) or regular (6-hour) infusion schedule for two or three cycles. Of 28 assessable patients, a complete or partial response was achieved in 15 (93.8%) of 16 who received rapid and in seven (58.3%) of 12 who received regular infusion therapy (p = 0.034). Rapid infusion significantly increased levels of MTX in the CSF (p < 0.001) and resulted in significant tumor volume reduction (p < 0.001). The mean tumor volume after the first, second, and third cycle of rapid infusion therapy was reduced to 34%, 14%, and 9%, respectively, of the initial volume, whereas the corresponding values were 54%, 42%, and 37% for regular infusion. The reduction between the second and third cycle was small and not significant for either schedule. Despite the longer median survival time in patients who underwent rapid MTX infusion and irradiation (> 60 compared with 20 months), the difference in survival was not significant (p = 0.147) because of the small number of patients enrolled. The median survival time was 39.3 months for all assessable patients who received high-dose MTX and radiation therapy, and the median relapse-free survival time was 35.2 months.

CONCLUSIONS

Rapid infusion enhanced both MTX penetration into the CSF and tumor response and may improve patient survival. Administration of three or more cycles of therapy should be carefully weighed in terms of cytoreductive benefits.

A new nematode, Ansiruptodera scapteromi sp.nov. (Nematoda: Aspidoderidae), recovered from the Argentinean water rat Scapteromys tumidis (Waterhouse, 1837) in Uruguay

This report describes a new species of aspidoderid nematode, Ansiruptodera scapteromi sp. nov., the second species to be reported in the genus Ansiruptodera Skrjabin and Shikhobalova, 1947. The A. scapteromi sp. nov. is the first species of the genus to be recorded from a rodent host. The new species is clearly different from the only other species, A. ansiruipta (Proença, 1937) Skrjabin and Shikhobalova, 1947, in that it possesses short lateral alae that terminate before the midbody; a smaller cephalic extremity; a shorter esophagus, pharynx, tail, and tail appendage; a smaller sucker; and longer spicules. The two species also differ in the numbers and arrangements of caudal papillae. A. scapteromi appears to be a parasite of capture and the water rats seem to have been infected from Edentata in Uruguay.

Respiratory impedance during positive expiratory airway pressure in patients with chronic obstructive pulmonary disease

The effect of positive airway pressure (5.0 hPa) on airway impedance (Za) and tissue impedance (Zt) during the expiratory phase in chronic obstructive pulmonary disease (COPD) patients was evaluated using random noise oscillation and a body box method. The results were then compared with those obtained from normal subjects. In normal subjects, there was no significant difference between non-expiratory positive pressure (NPEP) and positive expiratory pressure (PEP) for the Zar (real part) and Zai (imaginary part) at 10 Hz (Zar NPEP: 2.14 +/- 0.76, PEP: 1.96 +/- 0.79; Zai NPEP: 1.42 +/- 0.66, PEP: 1.40 +/- 0.70 hPa l-1 s). However, in COPD patients, Zar decreased significantly and the Zai increased significantly during PEP as compared to the values during NPEP (Zar NPEP: 7.10 +/- 1.88, PEP: 5.97 +/- 1.67, P < 0.05; Zai NPEP: -4.10 +/- 2.27, PEP: -2.99 +/- 2.62 hPa l-1 s, P < 0.05). These results suggested that both central and peripheral airway resistance decreased during PEP in COPD patients. Tissue compliance (Ct) calculated from the Zt increased significantly during PEP as compared to during NPEP, in both normal subjects and in COPD patients (normal NPEP: 0.024 +/- 0.004, PEP: 0.021 +/- 0.003, P < 0.05; COPD NPEP: 0.024 +/- 0.004, PEP: 0.014 +/- 0.004 l hPa-1, P < 0.001). This may have been indicative of the stiffened chest wall during PEP.

Hyperplasia of gastric mucosa in donor rats orally infected with Taenia taeniaeformis eggs and in recipient rats surgically implanted with the larvae in the abdominal cavity

Rats heavily infected with Taenia taeniaeformis larvae in the liver show a remarkable increase in their stomach weight, hyperplasia, and hypergastrinemia. However, it is unknown what causes these phenomena. Hence, as a preliminary study to investigate the importance of larval parasitism in the liver, two experiments were done. In the first experiment, 14 donor rats were orally inoculated with 3,000 T. taeniaeformis eggs. In the second experiment, 136-300 of the larvae obtained from the rats were surgically implanted into the abdominal cavity of 7 recipient rats. Gastrin levels and histopathological changes in the gastric mucosa were investigated. In all, 11 donor rats showed hypergastrinemia and hyperplasia, 5 recipient rats showed gastric mucosal hyperplasia accompanied by excessive mucous cell proliferation, and 2 recipient rats showed hypergastrinemia. These results suggest that parasitism of the liver by the larvae is not essential for the development of hyperplasia and that factors from the larvae might cause these phenomena.

Comparison of low attenuation areas on computed tomographic scans between inner and outer segments of the lung in patients with chronic obstructive pulmonary disease: incidence and contribution to lung function

BACKGROUND

The low attenuation areas on computed tomographic (CT) scans have been reported to represent emphysematous changes of the lung. However, the regional distribution of emphysema between the inner and outer segments of the lung has not been adequately studied. In this study the regional distribution of low attenuation areas has been compared by quantitative CT analysis and the contribution of the regional distribution to pulmonary function tests evaluated in patients with chronic obstructive pulmonary disease (COPD).

METHODS

Chest CT images and the results of pulmonary function tests were obtained from 73 patients with COPD. The lung images were divided into inner and outer segments in the upper (cranial), middle, and lower (caudal) sections. The percentage ratio of low attenuation area to corresponding lung area (LAA%) was then calculated. The LAA% of each segment was also compared with the results of pulmonary function tests.

RESULTS

The mean (SD) LAA% of the inner segment was 39.1 (18.5) compared with 28.1 (13.2) for the outer segment (p<0.0001). Linear and multiple regression analyses revealed that airflow limitation is closely correlated with the inner segment LAA% of the lower lung. In contrast, the carbon monoxide transfer factor is closely correlated with the inner segment LAA% of the upper lung.

CONCLUSION

Low attenuation areas on CT scans are more often found in the inner segment of the lung than in the outer segment, and the contribution of the inner segment to pulmonary function tests may be greater than the outer segment.

Histopathology and physiopathology of gastric mucous hyperplasia in rats heavily infected with Taenia taeniaeformis

Rats heavily infected with larval Taenia taeniaeformis show hyperplasia of the gastric mucosa accompanied by mucous cell proliferation, increase in the level of intragastric pH and hypergastrinemia. Sixty one rats were divided into 2 groups designed as infected (36 rats) and control (25 rats) group. These rats were examined with time course of the infection histopathologically and physiopathologically, during 14-112 days postinfection (DPI). In the infected rats, gastric mucosal hyperplasia began to be observed at 56 DPI, and the structural disturbance of zymogenic units in the corpus and mucous units in the antrum had increased with time. However, the degree of these changes in the antrum was weaker than those in the corpus. Alcianblue and/or PAS-positive cells increased in their numbers with time, and 4 types of cells other than typical surface mucous cell and mucous neck cell were observed by electron-microscopy. However, zymogenic and parietal cells decreased in their number after 56 DPI. Further, the infected rats showed changes in the serum concentration of alanine aminotransferase, aspartate aminotransferase, blood urea nitrogen, glucose and total protein. Some similarities with Menetrier's disease were discussed.

A second record of adult Ascarops strongylina (Rudolphi, 1819) (Nematoda: Spirocercidae) in a rodent host

Mature adults of Ascarops strongylina (Nematoda: Spirocercidae) were collected from a Manchurian zokor, Myospalax psilurus (Rodentia: Cricetidae), in Mongolia. This is the second record of adult A. strongylina from wild rodents and the first for M. psilurus as a definitive host of this nematode. Remnants of ground crustaceans (Porcellio sp.) and a dung beetle (Onthophagus sp.) were also found in the stomach of the zokor.

Evaluation of coproantigen diagnosis for natural Echinococcus multilocularis infection in red foxes

The validity of a coproantigen ELISA for Echinococcus multilocularis was evaluated by comparison of three diagnostic methods; autopsy, egg examination and the ELISA. Of 71 foxes, 39 were found to be infected with the cestode at autopsy. The overall mean of worm burdens was 3,451, but the number varied (1-34,522). The ELISA could detect 94.9% (37/39) of the worm positives and there were no false-positives. Two false-negatives were infected with 1 and 4 cestodes, whereas 3 cases with similar worm burdens (2, 4 and 6 worms) were diagnosed as positives. This indicates the detection limit of the assay may be equivalent to less than 10 (in the worm burden). On the other hand, egg examination showed low sensitivity (43.6%, 17/39). These results suggest the ELISA has a potential to replace for the conventional methods.

Acute response of the lung mechanics of the rabbit to hypoxia

We measured the change in total lung resistance (RL) and that in total lung elastance (EL) induced by hypoxia (n = 7) and compared the results with those by intravenous histamine bolus (n = 5) at three different positive end-expiratory pressure (PEEP) levels (2, 5, and 8 hPa) in open-chest and vagotomized rabbits. The percent increase ratio of RL (PIRR) and EL (PIRE) was defined as the change in RL and EL, respectively, induced by hypoxia compared with that in the normoxic condition, expressed as a percentage. PIR values for the change in RL and EL induced by bolus injection of histamine were also calculated. The PIRR and PIRE induced by hypoxia and by histamine were positive by a statistically significant amount at every PEEP level, except for the PIRE value at 8-hPa PEEP in the hypoxic challenge. The PIRE-to-PIRR ratio values in the hypoxic challenge at 2-hPa PEEP were significantly larger than those in the histamine challenge (hypoxia: 0.91 +/- 0.23%; histamine: 0.37 +/- 0. 065%, P < 0.05). The increase in EL induced by histamine in the acute phase has been reported to be mainly derived from tissue distortion secondary to bronchial constriction. Thus our results suggest that a part of the increase in EL by hypoxia was originated in different parenchymal responses from histamine and imply that this hypoxic response of lung parenchyma is sensitive to the increase in parenchymal tethering at high PEEP levels.

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.