Detection of antibodies to a recombinant gag protein derived from human endogenous retrovirus clone 4-1 in autoimmune diseases

To investigate whether human endogenous retroviruses (HERV) contribute to autoimmune diseases, we prepared a recombinant p30gag protein derived from clone 4-1 of the HERV family, using a baculovirus-vector system. This p30gag protein (CA41B) was approximately 30 kDa, as expected, and reacted with antibodies for p30gag purified from both murine and feline leukemia virus. This result suggested that the antigenic determinant for p30gag was well conserved in CA41B. Analysis of serum antibodies to p30gag in patients with autoimmune diseases was done by Western blotting. CA41B detected anti-p30gag antibodies in 48.3% of systemic lupus erythematosus (SLE) patients, 35.0% of Sjögren's syndrome (SS) patients, and 33.3% of mixed connective tissue disease (MCTD) patients, whereas no anti-p30gag antibodies were found in healthy subjects. This suggested that HERV p30gag or other retroviral p30gag proteins possessing the same antigenic determinant as CA41B may play a role in these diseases. Although detection of antibodies to HERV p30gag in autoimmune diseases is indirect evidence that HERV proteins are involved, this study showed that patients with autoimmune diseases have antibodies to HERV p30gag using a recombinant HERV protein rather than synthetic peptides based on HERV or retroviral proteins of other species.

Endoscopic papillary balloon dilatation may preserve sphincter of Oddi function after common bile duct stone management: evaluation from the viewpoint of endoscopic manometry

BACKGROUND

Endoscopic papillary balloon dilatation (EPBD) has been reported as a safe and effective alternative to endoscopic sphincterotomy in the management of common bile duct (CBD) stones; its effect on papillary function has yet to be elucidated.

AIM

To investigate sphincter of Oddi (SO) motility before and after EPBD to determine its effect on SO function.

PATIENTS AND METHODS

The papillary function of 10 patients with CBD stones was studied using endoscopic manometry before and one week after EPBD. The manometric studies were repeated one month after EPBD in seven patients.

RESULTS

One week after EPBD, CBD pressure, SO peak pressure, SO basal pressure, and SO frequency decreased significantly. One month after EPBD, however, all parameters increased although the increases in SO basal pressure and CBD pressure were not significant. There was no significant difference in values of any parameter before and one month after EPBD. No serious complications occurred.

CONCLUSION

These data suggest at least partial recovery of papillary function one month after the procedure. EPBD seems to preserve papillary function in treatment of CBD stones; a longer term follow up study with SO manometry should be performed to clarify the effect of EPBD on SO function.

Topical antigen provocation increases the number of immunoreactive IL-4-, IL-5- and IL-6-positive cells in the nasal mucosa of patients with perennial allergic rhinitis

To evaluate the role of Th2-type cytokines in the nasal mucosa which has been repeatedly exposed to antigen, an immunohistological study for IL-4, IL-5 and IL-6 was performed in patients with perennial allergic rhinitis and non allergic rhinosinusitis. The numbers of immunoreactive (ir)-IL-4, ir-IL-5 and ir-IL-6-positive cells were significantly higher in allergic mucosa than in nonallergic mucosa. In allergic mucosa, the numbers of these ir-cytokine-positive cells were significantly higher in the antigen-challenged site than in the control site. When the patients were divided into an early group (4-6 h after challenge) and a later group (15-25 h after challenge), only the change of ir-IL-4-positive cells was remarkable in the former group, whereas those of the ir-IL-4, ir-IL-5 and ir-IL-6-positive cells were significant in the latter group. These results suggest that antigen-induced upregulation of IL-4, IL-5 and IL-6 is important in the pathogenesis of perennial allergic rhinitis.

[Sensorineural hearing loss caused by middle ear surgery]

It is well known that sensorineural hearing loss rarely occurs after middle ear surgery. Five cases of postoperative sensorineural hearing loss were reviewed. These operations amounted to 0.9% of all middle ear operations in which the first author was involved. The causes of hearing loss were believed to be labyrinthitis through the fistula in cholesteatoma case 1, and acoustic trauma from the bone-cutting burr in cases 2 and 3. In cases 4 and 5 postoperative sensorineural hearing loss occurred several months after stapes surgery and the causes of hearing loss were unknown. On the basis of the available literature discussion focused on management of labyrinthine fistula, the acoustic effect of the bone-cutting burr and the possibility of sensorineural hearing loss caused by stapes surgery.

[Inhibitory effects of portal venous injection of type II collagen in collagen-induced arthritis]

Collagen-induced arthritis (CIA) is useful animal model for human rheumatoid arthritis. We investigated the inhibitory effects of portal venous (p.v.) injection of type II collagen (CII) in CIA. The arthritis was suppressed by p.v. injection of CII before immunization for CIA induction. The p.v. route was more effective than intravenous or intragastric routes in the induction of tolerance in CIA. The dose of CII necessary for CIA suppression was 10 micrograms/20 g body weight in p.v. injection. Both anti-CII IgG and anti-CII IgG 2 a levels in serum were reduced in mice injected CII before induction of CIA. However, anti-CII IgG 1 levels did not differ between mice injected with CII and mice injected with buffer alone. Thus, the specific reduction in anti-CII IgG 2 a levels in mice treated by p.v. injection before immunization suggests that the suppression of CIA could be responsible for hypofunction of Th 1 cells. Reduction of anti-CII IgG and suppression of arthritis were observed when CII was injected through portal vein after immunization for CIA as well.

[Systemic lupus erythematosus (SLE) and retrovirus]

Retrovirus have repeatedly been suggested as a possible trigger mechanism for animal and human autoimmune disease. Recent reports indicate that not only exogenous, but also endogenous, retrovirus could play an important role to induce autoimmunity. Here we described the relationship between retrovirus and systemic lupus erythematosus.

Chemohormonal therapy for malignant melanomas of the nasal and paranasal mucosa

We present three cases of primary malignant melanoma of the nasal or paranasal mucosa that were successfully treated by chemohormonal therapy using tamoxifen (TAM), an anti-estrogen agent. All of the patients showed good responses. TAM is widely known to be an anti-estrogen chemotherapeutic agent in the treatment of breast cancer and is thought to exert its anti-neoplastic effect in breast cancer tissues by competing with estrogen for estrogen receptors. The mechanism of the effect of TAM in malignant melanoma is not yet known. Although its anti-neoplastic mechanism requires further exploration, we believe that chemohormonal therapy may become important in multidisciplinary treatment of malignant melanoma of the nasal and paranasal mucosa.

[Familial astrocytoma associated with von Recklinghausen's disease: report of two cases]

Two cases of astrocytoma associated with von Recklinghausen's disease (neurofibromatosis type; NF-1) were reported. The first case wes a 60-year-old man who had been diagnosed as von Recklinghausen's disease on the basis of skin findings. Magnetic resonance imaging (MRI) showed a tumor in the left temporal lobe. Partial removal was performed with neuronavigator, and because of the existence of Rosenthal fiber the histological diagnosis was pilocytic astrocytoma. Radiation therapy was performed. The second case was a 6-year-old boy suffering from headache and left hemiparesis including his face. MRI showed a tumor with a cyst in the right thalamus and obstructive hydrocephalus. Initially CT-guided stereotactic biopsy was performed, and the histological diagnosis, on the basis of increased cellularity, pleomorphism and nuclear atypia without necrosis or vascular proliferation, was anaplastic astrocytoma. Radiation and chemo-immuno therapy were carried out after V-P shunt. It is well known that von Recklinghausen's disease (NF-1) is often associated with optic glioma (5-36%). In the literature, the glioma seldom occurs in other parts of the brain, supratentorial glioma especially is rare. Only two familial cases of supratentorial glioma associated with von Recklinghausen's disease have been reported. The prognosis of supratentorial glioma associated with NF-1 was poor in these reports. In this paper, the diagnostic and therapeutic problems are discussed.

[A case of simultaneous bilateral carotid occlusion]

Cases of bilateral cartoid occlusion have often been reported in the literature, but most of them were not examples of simultaneous bilateral carotid occlusion. Simultaneous bilateral cartoid occlusion appears to be rare, so we report one such case in this paper. A 68-year-old woman suddenly became unconscious, and was delivered to our hospital by ambulance. On arrival, she was comatose and showed decerebrate rigidity upon pain stimulation. Results of CT scan were normal, but cerebral angiography showed bilateral internal carotid artery occlusion at the carotid bifurcation. The patient was treated with urokinase and osmotic diuretics, but these were not effective and she died on the eleventh day after admission. Autopsy revealed that the bilateral internal carotid artery was occluded by fresh thrombi at the carotid bifurcation. The mitral valve was thickened by fibrous adhesion, and this was thought to indicate mitral stenosis. MRI before onset had shown flow void sign in the bilateral internal carotid artery. From the clinical course, and radiological and autopsy findings, we consider this case to be one of simultaneous bilateral carotid occlusion due to cardiogenic thrombi. Previous cases of bilateral carotid occlusion are reviewed and discussed.

[A case of a surgically treated extracranial internal carotid artery saccular aneurysm]

Extracranial internal carotid artery aneurysm is rare. Most cases are due to spontaneous or traumatic dissection of the cervical internal carotid artery. Here we report a case of surgically treated extracranial internal carotid artery (ICA) aneurysm. A 74-year-old man noticed a pulsatile mass just below the left mandibular angle. Intravenous digital subtraction angiography revealed multiple aneurysms in the systemic arteries, including the aortic arch, abdominal aorta and left extracranial ICA. It was decided to treat the aneurysms of the aortic arch and of the abdominal aorta conservatively. Cerebral angiography, however, showed a saccular aneurysm which projected latero-posteriorly at the C2 level of the left extracranial ICA. Although the patient had no previous ischemic event, we decided to treat this aneurysm surgically in view of the risk of cerebral ischemia caused by intraaneurysmal thrombus formation or rupture of the aneurysm by neck injury. The operation was performed under mild hypothermal general anesthesia. Electroencephalography was carried out during the operation. A skin incison was made from the anterior border of the sternocleidomastoid muscle to the pretragal region to expose the parotid gland. This skin incision, elevation of the parotid gland and division of the digastric muscle were useful for exposing the distal portion of the extracranial ICA. After trapping of the aneurysm, it was punctured and collapsed by aspiration and the dome was excised at its neck. The ICA was then reconstructed by suturing the cut neck of the aneurysm. Patency of the ICA was confirmed by postoperative angiography. The postoperative course was smooth except for hoarseness, which was caused by damage to a minor branch of the vagus nerve during exposure of the aneurysmal dome.

Effect of timolol and UF-021 (a prostaglandin-related compound) on pulsatile ocular blood flow in normal volunteers

The effects of topically applied timolol (a nonselective beta-blocker) and UF-021 (a prostaglandin-related compound) on pulsatile ocular blood flow (POBF) were investigated in 9 healthy volunteers. One drop of either UF-021 or timolol was instilled in one randomly selected eye and the fellow eye received physiologic saline. Before and 90 min after drop instillation, we measured intraocular pressure (IOP), POBF, heart rate (HR) and blood pressure (BP). After a washout interval of at least 1 week, the other drug was instilled in the previously treated eye. IOP, POBF, HR, and PB were measured following the same protocol. After timolol administration, IOP and POBF decreased significantly in the treated eye (26%, p = 0.01, and 13%, p = 0.02, respectively) and in the fellow eye (11%, p = 0.01, and 11%, p = 0.03, respectively). HR also decreased (10%, p = 0.03), but BP did not change significantly. After UF-021 administration, no significant changes were found in IOP, POBF, HR, or BP. Our results suggest that in normal subjects timolol decreases POBF in both the treated and the untreated eyes, whereas UF-021 has no action on either IOP or POBF.

Improvement by eicosanoids in cancer cachexia induced by LLC-IL6 transplantation

Cachexia frequently occurs in the late stages of cancer, and is difficult to manage. We previously reported that interleukin-6 (IL-6) cDNA transfection into Lewis lung carcinoma (LLC-IL6) induced cachexia-like symptoms in C57BL/6 mice. This was thought to be a useful experimental model of cancer cachexia. We have examined the effects of two eicosanoids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), in order to evaluate whether they could relieve cachexia. LLC-IL6-bearing animals were divided into three treatment groups receiving DHA, EPA or water as the control; 80-microliter samples of these compounds (purity > 95%) were administered orally by catheter daily starting 7 days after tumor transplantation. Tumor growth curves were similar in the three groups. There were no differences in water or food intake in the three groups. However, body weight, a marker of cachexia, was significantly higher in treated mice than in the control group. Sixteen days after tumor transplantation, the mean body weight was 17.45 g (P < 0.05), 17.2 g and 16.41 g in the groups receiving DHA, EPA and water respectively. The eicosanoids did not affect serum levels of IL-6. Ubiquitination of muscle protein, a marker of proteolysis coupled to cachexia, was compared in LLC-IL6- and LLC-transplanted mice. The eicosanoids prevented the ubiquitination of approximately 180 kDa protein. These results suggest that eicosanoids may prevent the cachexia mediated by IL-6.

Cytochemical effects of in vitro dopamine treatment on the Na-KATPase activity in strial marginal cells

Dopamine is often used clinically for the treatment of patients with shock. In a previous study, the Na-KATPase (K-NPPase) activity of strial marginal cells was inhibited after the repeated in vivo administration of dopamine hydrochloride. In the present study, the K-NPPase activity of strial marginal cells was determined using a cerium-based cytochemistry after an in vitro incubation with dopamine. The enzyme reaction product was found in untreated normal strial marginal cells, but it was almost completely undetectable after an in vitro treatment with 10 mM dopamine. This finding suggested that dopamine directly inhibited the Na-KATPase activity of strial marginal cells, and that these cells might have a dopamine receptor.

[The new laser Doppler velocimetry for the measurement of retinal circulation and its clinical application]

We developed a new laser Doppler instrument to measure retinal blood flow. This instrument is equipped with an eye tracking system, which maintains the laser beam on the retinal vessel, thus enabling the measurement of patients with poor visual acuity and poor fixation. In diabetic patients even those without retinopathy, the retinal blood flow decreased compared to the control subjects. This was mainly the result of decreased retinal blood speed and no significant change in the arterial diameter. In diabetic patients requiring panretinal photocoagulation, we studied the regional changes in retinal blood flow following superior or inferior half fundus argon laser treatment, which produced a significant retinal blood flow decrease only in the treated area. We also studied the retinal circulatory changes in retinal branch vessel occlusion. In retinal branch view occlusion, the blood flow in arteries supplying the affected lesion showed 80-90% decrease compared to the arteries supplying the unaffected region. In retinal branch artery occlusion, the retinal blood flow in occluded arteries showed 40-50% decrease compared to the non-occluded arteries. In one patient with retinal branch vein occlusion in whom we measured the retinal blood flow over 18 months, the blood flow increased with the development of collateral vessels. The results showed that retinal circulatory abnormalities can be also evaluated quantitatively during the course of retinal vascular occlusive disease by our newly developed laser Doppler instrument, which proved that this instrument is a clinically very useful tool.

Induction of IL-6 production by bone marrow stromal cells on the adhesion of IL-6-dependent hematopoietic cells

Cellular interactions between hematopoietic cells and stromal cells play crucial roles in the proliferation and differentiation of the hematopoietic cells. Interleukin-6 (IL-6)-dependent 7TD1 cells markedly proliferated without IL-6 when they were co-cultured with hematopoietic-supportive bone marrow stromal cells, HESS-5 cells and HESS-1 CL.3 cells, which can support long-term hematopoiesis in vitro with but not without direct cell contact, cell contact being prevented with a microporous membrane. The production of IL-6 and the amount of IL-6 mRNA in hematopoietic-supportive stromal cells but not 7TD1 cells significantly increased only when the stromal cells were co-cultured in direct contact with 7TD1 cells. Furthermore, the amount of IL-6 mRNA increased according to the number of 7TD1 cells co-cultured. These inductions were not observed on co-culture with a murine myeloid cell line, M1 cells, or on the addition of the co-culture supernatant. These results suggest that 7TD1 cells transmit the signal to stromal cells that enhances IL-6 production by stromal cells via direct cell contact. A certain specific molecule for transduction of the signals may exist on the surface membrane of stromal cells and hematopoietic cells.

Hypersensitivity of NIH3T3 cells transformed by H-ras gene to DNA-topoisomerase-I inhibitors

We examined the effects of the introduction of H-ras oncogene into murine cell line NIH3T3 on growth inhibition by topoisomerase-I (topo-I) inhibitors. The H-ras-transformed cells (pT22-3) showed approximately 12-fold increased sensitivity to a novel topo-I inhibitor, NB-506 [6-N-formylamino-12,13-dihydro-1,11-dihydroxy-13-(beta-D-glucopyranosyl) -5H-indolo(2,3-a)pyrrolo(3,4-c) carbazole-5,7(6H)-dione], compared with the parental NIH3T3 cells. pT22-3 also showed increased sensitivity to other topo-I inhibitors such as camptothecin (approx. 3.0-fold) and CPT-11 (irinotecan, approx. 3.0-fold). Transformation of NIH3T3 by another oncogene (erbB2) did not affect their sensitivity to these topo-I inhibitors. pT22-3 had approximately 32-fold higher topo-I activity than NIH3T3, but the same topo-I content. In a cell-free system, topo-I activity was increased 2-fold by addition of the H-ras protein precipitated from pT22-3 cells. Topo I in the nuclear extract of pT22-3 was eluted easily by low concentrations of NaCl compared with that of NIH3T3, suggesting a qualitative change in pT22-3 topo 1. Increased phosphorylation of topo I was observed in pT22-3. Furthermore, NB-506 decreased the amount of the GTP-bound form of the H-ras product in pT22-3 cells. These results suggest that the high growth-inhibitory effect of a topo-I inhibitor, NB-506, on H-ras-transformed NIH3T3 cells is due to the H-ras-mediated signal-transduction pathway.

[Tympanoplasty on only hearing ears]

Tympanoplasty on only hearing ears was performed on 11 patients in Osaka University Hospital and Osaka Rosai Hospital during 1986 1994; this was 0.68% of all cases of middle ear surgery. The patients consisted of 5 with cholesteatoma, 5 with chronic otitis media and 1 with cholesterin granuloma. The mean age was 47.6 years (13-68 years) and the mean follow-up period was 2 years and 7 months (6 months-4 years). Postoperative hearing results was obtained in 9 patients (81.8%) according to the criteria of Otology Japan (1987), and all ears were dry at the final examination. Compared with the preoperative hearing level, postoperative hearing level showed improvement in 3 cases, not in 7 cases (within difference of 5 dB) and deterioration by 10-15 dB in 1 case. Although indications for surgery on only hearing ears are still controversial, we suggest the following: 1) patients with cholesteatoma should be operated on in the ordinary way; 2) patients with chronic otitis media should be operated on only by myringoplasty; 3) all patients must be operated on very carefully by skillful surgeons.

[Chemohormonal therapy for malignant melanomas]

The management of malignant melanoma of the head and neck is controversial in view of the poor prognosis. Although radical surgery has been proposed as the best therapy for mucosal malignant melanoma, it has seldom been performed because of the extent of tumors and anatomical difficulties. In spite of testing various methods such as chemotherapy, radiotherapy and immunotherapy, that have been suggested for treatment of this malignant disease, there are still no well established effective therapies. We attempted chemohormonal therapy including TAM (Tamoxifen), an anti-estrogen agent, in six patients with primary malignant melanoma from 1993 to 1996. Three patients had a complete response, two had a partial response, and one showed no change. The toxicity in this protocol was found to be low. Generally, the patients showed good responses to chemohormonal therapy. TAM has been previously best known as a therapeutic agent for mammary cancer. Its anti-cancer effect is thought to be due to the anti-estrogen activity revealed by binding to the estrogen receptor competitively with estrogen in the tumor tissue. However, the mechanism of the action of TAM against malignant melanoma has not been clarified yet. Although its anti-cancer mechanism should be further explored, it is suggested that this chemohormonal therapy could occupy a very important position in the multidisciplinary therapy of malignant melanoma of the head and neck.

[A case of chronic tuberculous pyothorax associated malignant lymphoma]

The patient was 69-year-old male. He has a history of treatment for tuberculosis by artificial pneumothorax about 47 years ago. He was admitted an another hospital under the diagnosis of tuberculous pyothorax. He was transferred to our hospital because of chest pain and fever. Laboratory findings on the admission were as follows: ESR was 120 mm/hr, CRP was 20.22 mg/dl and other data were almost within normal limits. Chest X-ray showed a massive shadow in the right lower lung field, adjacent to the chest wall. Computed tomography (CT) showed tumor shadow with low density and invasions into the adjacent chest wall. Histological examination of surgically excised tumor biopsy revealed malignant lymphoma. The patient's condition improved and the size of tumor decreased temporarily by chemotherapy. Then, he began to complain of chest pain and high fever, and tumor in the chest wall invaded into the whole chest wall. He died of disseminated intravascular coagulation despite continuing chemotherapy. Postmortem examination revealed the following findings : the tumor existed mainly in the parietal pleura or the chest wall, adjacent to the lesion of pyothorax, and immunohistochemical examination showed that tumor was malignant lymphoma, diffuse, large B-cell type. Recent studies have shown a close association between EBV infection and pyothorax-associated lymphoma. We have to keep in mind the possible development of malignant lymphoma following tuberculous pyothorax, when we see patients complaining of fever or chest pain with tuberculous pyothorax.

Functional coupling of adenosine A2a receptor to inhibition of the mitogen-activated protein kinase cascade in Chinese hamster ovary cells

Activation of Gs-coupled receptors enhances the increase in cyclic AMP mediated by adenylate cyclases. As it has been shown that cyclic AMP inhibits the epidermal growth factor-activated mitogen-activated protein kinase (MAPK) signalling pathway, stimulation of Gs-coupled receptors may lead to the inhibition of MAPK activation. To investigate the effect of a Gs-coupled receptor on the MAPK cascade, we cloned the adenosine (Ado) A2a receptor from a guinea-pig leucocyte cDNA library, and established Chinese hamster ovary (CHO) cells stably expressing the receptor (CHOAdoA2R). The [3H]5'-N-ethylcarbamoyladenosine (NECA) binding characteristics (Kd = 91.0 +/- 5.4 nM, Bmax = 707 +/- 11 fmol/mg of protein, n = 3) and NECA-induced cyclic AMP production indicate that the cloned Ado A2a receptor was functionally expressed in the cells. In CHO cells, thrombin induced intracellular Ca2+ increase and MAPK activation through the intrinsic G-coupled receptor. In CHOAdoA2R cells, NECA partially inhibited thrombin-elicited MAPK activation. When combining NECA-treatment with 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid acetoxymethyl ester (BAPTA-AM) loading, a nearly complete inhibition of the MAPK activation occurred. Forskolin also partially inhibited the MAPK activation and synergized with BAPTA-AM, suggesting that partial inhibition of MAPK activation by NECA results from cyclic AMP production via Ado A2a receptor activation. The same synergism of MAPK inhibition between wortmannin and BAPTA-AM was observed, but not between wortmannin and NECA. These results suggest that cyclic AMP production through Ado A2a receptor inhibits thrombin-elicited MAPK activation by a Ca(2+)-independent/wortmannin-sensitive pathway in CHO cells.

Characterization of murine stromal cell clones established from bone marrow and spleen

Stromal cell lines were established by irradiating adherent layers of bone marrow and spleen cells in Dexter-type long-term culture with X-rays. Some of these cell lines support myelopoiesis and/or B lymphopoiesis in vitro. Furthermore, the characteristics of these stromal cell lines were studied. Cytokine activity was detected in the conditioned media from all hematopoietic-supportive and non-supportive stromal cells. Quantitative reverse transcriptase-polymerase chain reaction analysis revealed that the mRNAs of macrophage colony-stimulating factor and stem cell factor, but not that of Interleukin-3, were detectable in all the hematopoietic-supportive and non-supportive stromal cell lines. The transcripts of granulocyte colony-stimulating factor, interleukin-6, interleukin-7, and leukemia inhibitory factor were expressed in a wide variety of cell lines. Most stromal cell lines synthesized mRNA of c-mpl, the ligand of which stimulates megakaryopoiesis and thrombopoiesis. These observations indicate that the pattern of mRNA expression of cytokines is not correlated with the hematopoietic-supportive ability of stromal cell lines. There was a significant difference in the efficiency of adhesion of lineage marker-negative bone marrow cells to fibroblasts and stromal cell lines. This appears to be correlated with the hematopoietic-supportive ability of the stromal cell lines.

[Distribution of ventilation-perfusion ratios in paraquat-induced interstitial pneumonia in dogs]

To clarify the mechanism of hypoxemia observed in interstitial lungs diseases we investigated the V(A)/Q distribution in the paraquat-induced pneumonitis of the dogs. Sixteen mongrel dogs were given 20mg/kg of paraquat per os repeatedly with the dose and times of administration modified according to the general status of the dogs. Ventilation-perfusion relationships were measured using multiple inert gas elimination techniques, and these parameters were compared to arterial blood gases. The same procedures were also done in 11 normal dogs. Arterial oxygen tension (Pao2) was significantly lower and alveolar-arterial oxygen gradient )A-aDo2) was significantly larger in paraquat dogs than normal dogs. In V(A)/Q measurement of paraquat dogs, mean shunt was 5.3% (range 0-28.8%), and there was a mean of 10.0% of blood flow to very low V(A)/Q units (V(A)/Q < 0.1, range 0-43.4%). These values were larger than those of normal dogs (p<0.05, respectively) but dogs with large shunt or blood flow to low V(A)/Q units were not many in paraquat group. In the paraquat dogs, PaO2 significantly correlated with a shunt (r=-0.69, p < 0.01) and blood flow to low V(A)/Q (<0.1) units (r=-0.77, p<0.01) and it also correlated with dispersion of blood flow (log SD(Q), r=-0.66, p,0.01). Pathological study of paraquat lung showed large variety of interstitial pneumonia and fibrosis, and morphometical analyses did not demonstrate structure-function correlation in paraquat dogs. From these results, we concluded that V(A)/Q mismatch including increased very low V(A)/Q units is important as a cause of arterial hypoxemia in interstitial lung diseases.