Functional analysis of human mitochondrial receptor Tom20 for protein import into mitochondria

The mitochondrial import receptor translocase of the outer membrane of mitochondria (Tom20) consists of five segments, an N-terminal membrane-anchor segment, a linker segment rich in charged amino acids, a tetratricopeptide repeat motif, a glutamine-rich segment, and a C-terminal segment. To assess the role of each segment, four C-terminally truncated mutants of the human receptor (hTom20) were constructed, and the effect of their overexpression in COS-7 cells was analyzed. Expression of a mutant lacking the tetratricopeptide repeat motif inhibited preornithine transcarbamylase (pOTC) import to the same extent as the wild-type receptor. Thus, overexpression of the membrane-anchor and the linker segments is sufficient for the inhibition of import. Expression of either the wild-type receptor or a mutant lacking the C-terminal end of 20 amino acid residues stimulated import of pOTC-green fluorescent protein (GFP), a fusion protein in which the presequene of pOTC was fused to green fluorescent protein. On the other hand, expression of mutants lacking either the glutamine-rich segment or larger deletions inhibited pOTC-GFP import. In vitro import of pOTC was inhibited by the wild-type hTom20 and the mutant lacking the C-terminal end, but much less strongly by the mutant lacking the glutamine-rich segment. On the other hand, import of pOTC-GFP was little affected by any of the forms of hTom20. In binding assays, pOTC binding to hTom20 was only moderately decreased by the deletion of the glutamine-rich segment, whereas pOTC-GFP binding was completely lost by this deletion. Binding of pOTCN-GFP a construct that contains an additional 58 N-terminal residues of mature OTC, resembled that of pOTC. All of these results indicate that the region 106-125 containing the glutamine-rich segment of hTom20 is essential for binding and import stimulation in vivo of pOTC-GFP and for inhibition of in vitro import of pOTC. The results also indicate that this region is important for mitochondrial aggregation. The different behaviors of pOTC and the pOTC-GFP chimera toward hTom20 mutants is explicable on the basis of the conformation of the precursor proteins.

Activation of 11 beta-hydroxysteroid dehydrogenase by dehydroepiandrosterone sulphate as an anti-hypertensive agent in spontaneously hypertensive rats

The anti-hypertensive properties of dehydroepiandrosterone sulphate (DHEAS) have been investigated by studying its effects on blood pressure, on serum concentrations of corticosterone and dehydrocorticosterone, and on 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) activity in spontaneously hypertensive rats (SHR). SHR were given intraperitoneal injections of DHEAS (10 mg day-1 for 70 days) from six to 16 weeks of age. The blood pressure-time curve was significantly (P < 0.05) suppressed immediately after administration of DHEAS. There was no difference between the heart rates of control and DHEAS groups. Serum concentrations of corticosterone and dehydrocorticosterone in the DHEAS group were significantly (P < 0.05) lower than those of the control group. The dehydrocorticosterone/corticosterone concentration ratio was, however, significantly (P < 0.05) higher in the DHEAS group, suggesting that treatment with DHEAS enhanced the overall interconversion of corticosterone to dehydrocorticosterone. The activity of 11 beta-HSD in specific organs of the DHEAS group was affected, characteristic changes being increases in the kidney (14-58%), decreases in the liver (11-27%) and no change in the testis. Direct addition of DHEAS to 11 beta-HSD preparations from the kidneys of control SHR had the same effect as that observed in the in-vivo experiments. The fall in serum corticosterone in the DHEAS group is considered to be related, at least partly, to increased activity of kidney 11 beta-HSD. The inverse correlation of kidney 11 beta-HSD activity with serum corticosterone and blood pressure (-r = 0.628, P < 0.01, and -r = 0.478, P < 0.05, respectively) suggest that DHEAS delayed the development of hypertension in SHR by selective promotion of kidney 11 beta-HSD activity which in turn resulted in lower serum concentrations of corticosterone and its minimal aldosterone-like activity.

Relationship between disc displacement and morphologic features of skeletal Class III malocclusion

The present study assessed the relationship between disc displacement and facial morphologic features in 48 patients with skeletal Class III malocclusion. Clinical examination, standardized lateral oblique temporomandibular joint radiographs, and cephalographs were used to investigate this relationship. Disc displacement was evaluated by the presence of joint sounds (clicking and crepitation) or restricted condylar translation at maximal mouth opening. Thirty-two patients with signs of disc displacement were compared with 16 patients without signs of disc displacement. Results showed that patients with signs of disc displacement had a significantly larger gonial angle and/or SN-MP of the mandible. Thus, morphologic features of patients with skeletal Class III malocclusion may represent a risk factor for the development of disc displacement.

Differential upregulation of rat Na-K-Cl cotransporter, rBSC1, mRNA in the thick ascending limb of Henle in different pathological conditions

BACKGROUND

Na-Cl cotransport across the apical membrane of epithelial cells in the thick ascending limb of the loop of Henle (TAL) plays a major role in salt accumulation for hypertonic medullary interstitium. The electroneutral, rat bumetanide-sensitive sodium transporter, rBSC1, is involved in this process. We studied the level of rBSC1 mRNA in dehydration and cardiac failure, since sodium transport in TAL may be enhanced in both conditions in spite of the difference in extracellular fluid accumulation.

METHODS

Male Sprague-Dawley rats were deprived of water for 24 hours and myocardial infarction of about 40% of left ventricular circumference was induced in another group of rats that later developed congestive heart failure (CHF). Digoxigenin-labeled cRNA probe for rBSC1 was constructed using polymerase chain reaction (PCR), and Northern blot analysis was performed using RNAs from renal outer medulla. By inducing a point mutation at the middle of PCR product, we compared the amount of rBSC1 transcripts in the renal cortex using competitive PCR, since TAL represents a small fraction of the total cortical tissue.

RESULTS

Northern analysis showed a significant increase in rBSC1 mRNA in the renal outer medulla of both dehydrated and CHF rats. In the renal cortex, however, the increase was noted only in CHF by competitive PCR. In situ hybridization using the riboprobe for northern analysis demonstrated that the transcript signal in dehydrated rats was intensified segmentally in TAL located in the inner stripe of outer medulla. Western analysis and immunohistochemistry using a specific antibody against rBSC1 confirmed the distinct segmental enhancement of apical protein expression in dehydration and diffuse enhanced expression in CHF.

CONCLUSIONS

rBSC1 is differentially upregulated in different pathological conditions.

Inhibitory effects of prostaglandin D2 against the proliferation of human colon cancer cell lines and hepatic metastasis from colorectal cancer

The inhibitory action of prostaglandin D2 (PGD2) and its effect on the cell cycle were examined in cell lines SW480 and LS174T of human colon cancer. The growth of the cell lines were assessed 24 h and 48 h after the addition of 1.0 microgram/ml and 10.0 micrograms/ml PGD2. The growth of SW480 cells was inhibited 48 h, but not 24 h, after the addition of 1.0 microgram/ml, and 24 h and 48 h after the addition of 10.0 micrograms/ml, while that of LS174T was inhibited by both doses after 24 h and 48 h. S-Phase DNA synthesis in the SW480 cells was significantly blocked 24 h after the addition of 10.0 micrograms/ml PGD2. The cell cycle of LS174T cells was arrested at the G0 + G1 phase 24 h after the addition of 1.0 microgram/ml and 10.0 micrograms/ml PGD2. The correlation between hepatic metastasis and PGD2 concentration in human cancer tissue was examined. The mean value of PGD2 concentrations in the primary cancer tissue was significantly lower in the hepatic metastasis group than that in the group without hepatic metastasis. These findings suggest that measuring the PGD2 in cancer tissue may be useful for detecting and predicting the hepatic metastasis from human colorectal cancer.

Pharmacological properties of the CO2/H+-sensitive area in the ventral medullary surface assessed by the effects of chemical stimulation on respiration

We recently discovered that CO2/H+-sensitive neurons in the ventral medullary surface (VMS) are immunoreactive to glutamate, glutamic acid decarboxylase (GAD), calcineurin and cAMP. We then tested the hypothesis that glutamate, GABA, calcineurin and cAMP affect the activity of CO2/H+-sensitive neurons in the VMS. Using male Wistar rats anesthetized with urethane and pentobarbital, we checked for changes in relative tidal volume (VT) and respiratory frequency (f) in response to injecting the VMS with a variety of test agents dissolved in mock CSF. Respiratory changes occurred immediately and were dose-dependent. (1) 200-1600 pmol Glutamate increased VT but decreased f. The glutamate effect was never abolished by concomitant injection of AP5, a NMDA receptor antagonist, but was abolished by CNQX, an AMPA receptor antagonist, indicating predominance of AMPA receptors in the CO2/H+-sensitive neurons in the VMS. (2) 200-1600 pmol GABA decreased both VT and f. The GABA effect was never abolished by concomitant injection of saclofen, a GABA(B) receptor antagonist, but was abolished by bicuculline, a GABA(A) receptor antagonist, indicating predominance of GABA(A) receptors in the CO2/H+-sensitive neurons in the VMS. (3) 4-32 microg Calcineurin, a Ca2+/calmodulin-dependent protein phosphatase 2B, and 200-1600 pmol FK506, selective inhibitor of calcineurin, had no effect on respiration when they were applied extracellularly, but 400-3200 pmol BAPTA-AM, an intracellular Ca2+-chelating agent, decreased both VT and f, indicating involvement of intracellular Ca2+ in the excitatory mechanisms of respiration. (4) 100-800 pmol IBMX, an enhancer of intracellular cAMP, decreased both VT and f, indicating involvement of cAMP in the inhibitory mechanisms of respiration. These results indicate that the CO2/H+-sensitive neurons in the VMS contain glutamate and/or GABA in cytoplasma, possess AMPA and/or GABA(A) receptors on surface of plasma membrane, and compose the internal circuit, and that their activities are regulated by Ca2+ and cAMP.

Expression analysis of two mutant human ornithine transcarbamylases in COS-7 cells

Ornithine transcarbamylase (OTC) is located in the mitochondrial matrix of the liver and small intestine and catalyzes the second step of the urea cycle. OTC deficiency (OTCD) is an X-linked inborn error of metabolism and causes hyperammonemia. We reported in 1992 the A152V and G195R mutations in patients with OTCD. These mutant OTC cDNAs were prepared by site-directed mutagenesis using the polymerase chain reaction (PCR). The wild-type and mutant cDNAs were transiently expressed in COS-7 cells. The wild-type cDNA gave an OTC activity of 1180 +/- 47 nmol/min per mg protein. The OTC activities of the A152V and the G195R mutants were 3.7% and 2.5% of that of wild-type, respectively. Immunoblot analysis showed that the quantities of OTC proteins in the A152V and G195R mutants were 29% and 12% of that of wild-type, respectively. In pulse-labeling and pulse-chase experiments, the precursor form of OTC was synthesized and processed to the mature form. The A152V mutant OTC was processed to the mature form as rapidly as the wild-type precursor. However, the processed, mature form of the mutant OTC was rapidly degraded, presumably in the mitochondrial matrix. These results indicate that OTCD with the A152V mutation is due both to rapid degradation of the processed, mature form, and to a lower specific activity of the remaining protein.

Basaloid-squamous cell carcinoma of the oral mucosa: report of two cases and study of the proliferative activity

Two cases of basaloid-squamous cell carcinoma (BSC) of the oral mucosa are described. The first case occurred at the floor of the mouth in a 58-year-old man, and the second case occurred at the mandibular gingiva in a 79-year-old woman. The laboratory data of the first case showed a positive response to hepatitis C virus antibody. In the first case, the tumor mass measured 4 x 4 cm in size, and was located at the lingual side of the median mandible beside the sublingual gland. In the second case, the tumor mass measured 25 x 15 mm in size, and was located in the alveolar mucosa of the right mandible. Histologically, both tumors showed a neoplastic epithelium arranged in a solid pattern with evidence of peripheral palisading, central necrosis, and some squamous differentiation. The proliferative activities of the BSC were compared with conventional squamous cell carcinomas (SCC) in the oral floor and gingiva, respectively, by employing a sensitive argyrophilic nuclear organizer region (AgNOR) staining method. The number of AgNOR per nucleus of the BSC was higher than that of any other SCC cases. The results support the opinion that BSC of the oral mucosa has a worse prognosis than conventional SCC.

A case of rapidly progressing small cell lung cancer incidentally found during the course of renal failure

A 65-year-old man with rapidly progressing small cell lung cancer found in the course of renal failure is reported. The patient had a medical history of hypertension, diabetes mellitus, and cardiovascular disease. Hemodialysis was introduced following renal failure, but pneumonia resulted in a transient exacerbation and his complaint of general fatigue did not improve. Examination for the fatigue revealed no apparent abnormalities. Three months later, he died of small cell lung cancer.

[Pulmonary emphysematous changes associated with Pneumocystis carinii pneumonia in an AIDS patient]

A 60-year-old man was admitted to our hospital complaining of non-productive cough. He had worked in Africa and received a blood transfusion after a traffic accident in 1985. On admission, the patient had remarkable hypoxemia and a decreased CD4+ lymphocyte count. A serological test for human immuno-deficiency virus (HIV)-1 was positive. His chest radiographs showed diffuse reticular and linear opacities, and broncoalveolar lavage findings established a diagnosis of Pneumocystis carinii pneumonia (PCP). A high-resolution CT of the chest revealed peripheral infiltrates and low attenuation areas (LAA) consistent with severe emphysematous alterations. We administered high-dose methylprednisolone and trimethoprim-sulphamethoxazole (TMP-SMX). Because of marked eosinophilia, TMP-SMX was discontinued, and the patient was given inhaled pentamidine isothiocyanate. Although there was a striking clinical improvement, the emphysema-like lesion on chest CT remained unaltered. LAA on CT had been modest in 1994, but had markedly enlarged during the three years thereafter, leading us to speculate that most of the LAA lesions recognized on admission might have developed in association with PCP. Pulmonary function tests showed an obstructive ventilatory defect and impaired diffusing capacity. Although PCP classically presents with diffuse ground-glass or fine granular opacities, thin-walled cavities or other atypical findings have recently been reported, especially in AIDS patients. There have been several reports about emphysema-like lesions associated with PCP. It was suggested that these lesions might be due to lung parenchyma destruction induced by HIV itself or increased elastase release from HIV-infected macrophages. This is the first report of PCP with pulmonary emphysematous lesions in Japan.

[Acute exacerbation of subacute interstitial pneumonia after thoracoscopic lung biopsy]

A 55-year-old woman was admitted to our hospital with progressive dyspnea that had begun one month before. Chest rentogenogram revealed groundglass appearance and reticular shadows bilaterally. Pulmonary function tests showed both decreased vital capacity and diffusing capacity. Bronchoalveolar lavage fluid had a high lymphocyte fraction with a low CD4+/CD8+ ratio. Thoracoscopic lung biopsy revealed thick, fibro-edematous interstitium and diffuse infiltration of lymphocytes. We also observed an intra-alveolar exudate with infiltration of histiocytes and lymphocytes. The clinical features and pathological findings were consistent with subacute interstitial pneumonia, which was the entity proposed by Kawabata and colleagues. The patient developed acute respiratory failure four days after lung biopsy and died despite steroid pulse therapy. Although subacute interstitial pneumonia has been reported to respond to steroid therapy, and to have a good prognosis, we believe that subacute interstitial pneumonia could fatally worsen when associated with lung biopsy, infection, or some other stimulus.

Topology and immunohistochemistry of proton-sensitive neurons in the ventral medullary surface of rats

We aimed to clarify the topology and immunohistochemistry of CO2/H+-sensitive neurons in the ventral medullary surface (VMS), the central chemoreceptor area in rats. Inhalation of 3 and 7% CO2 in air significantly decreased pH in arterial blood and increased paCO2, which caused hyperpneic and tachypneic responses. Following inhalation of 3 and 7% CO2 in air for 5 min, the density of c-Fos-immunoreactive (IR) neurons increased stepwise not only in the 3rd-5th divisions of the VMS (between the caudal end of the nucleus corporis trapezoidei and the caudal end of the area postrema), but also in the rostroventromedial medulla (RVMM). Following inhalation of 7% CO2 in air for 5 min, glutamate-, glutamic acid decarboxylase (GAD)-, calcineurin- and cAMP-IR neurons were found not only in the VMS, but also in the RVMM. The topology of these neurons was similar to that of the c-Fos-IR neurons. No immunoreactivity was found for serotonin, substance P, somatostatin, cholecystokinin-octapeptide, methionine-enkephalin, choline acetyltransferase, tyrosine hydroxylase, phenylethanolamine N-methyltransferase, NO-synthase, S-100, calbindin-D, calmodulin, or parvalbumin. The densities of c-Fos-, glutamate-, GAD-, calcineurin- and cAMP-IR neurons were almost zero in the 1st division of the VMS, but became higher along the 2nd-4th divisions of the VMS. Regression lines of the density against the 1st-4th divisions of the VMS were significantly linear. These results indicate that H+-sensitive neurons are common in the 4th-5th divisions of the VMS, and that they are glutamatergic, GABAergic, and containing calcineurin and cAMP.

New successful treatment with disinfectant for atopic dermatitis

For the treatment of atopic dermatitis, a variety of therapies are used including folk medicine. At present, there is no single treatment which is effective to cure the symptoms of atopic dermatitis completely in all patients. We are drawing attention to the high isolation rate of Staphylococcus aureus when starting disinfectant treatment combined with topical steroid therapies for the purpose of killing S. aureus. As a result, we examined many patients in whom almost a complete remission was obtained even after short periods of therapy, though it had been difficult to obtain improvement by conventional treatments. In many patients, IgE values and reagin antibody titer decrease dramatically soon after starting treatment. As a disinfectant, 10% povidone-iodine solution was used. We investigated also the effect of iodine contained in the povidone-iodine solution on the thyroid gland.

Circadian blood pressure rhythm in patients with higher and lower spinal cord injury: simultaneous evaluation of autonomic nervous activity and physical activity

OBJECTIVE

To examine the relationships among the circadian rhythms of blood pressure, autonomic nervous function, and physical activity of patients with varying levels of spinal cord injury.

DESIGN AND METHODS

We studied 19 patients with spinal cord injury [10 tetraplegic patients with cervical cord injury (C4-C7), and nine paraplegic patients with thoracic cord injury (Th6-Th12)] compared with 16 control subjects. A new multibiomedical recorder was used to measure blood pressure (every 30 min), cardiac vagal activity (hourly frequency of R-R50), and physical activity (integrated acceleration/min) for 24 h under hospital conditions. Systemic sympathetic nervous activity and sympathoadrenal functioning were assessed by examination of hormone levels in the blood.

RESULTS

Daytime and night-time values were compared; the variations in systolic and diastolic blood pressures and heart rate were slight in members of the tetraplegia group, but almost normal differences were observed in members of the paraplegia group. The circadian profile of cardiac vagal activity was normal for both patient groups, suggesting that an alteration in the sympathetic nervous rhythm had occurred in the tetraplegic patients. The plasma norepinephrine level was lower in members of the tetraplegia group than it was in members of the control group (P< 0.001), but was normal in members of the paraplegia group. The plasma level of epinephrine was lower in members of the tetraplegia (P< 0.05) and the paraplegia (P < 0.1) groups than it was in members of the control group. Daytime physical activity of members of both groups of patients was lower than that of subjects in the control group (P< 0.001 for both).

CONCLUSION

The central sympathoexcitatory pathway to the upper thoracic cord plays a critical role in the maintenance of normal circadian blood pressure rhythm in humans. Motor nerve functioning and sympathoadrenal secretion are not essential to this regulation.

[A case of interstitial pneumonia induced by intravesical administration of bacillus Calmette-Guerin (BCG)]

A 61-year-old man with superficial bladder cancer, which was detected after he complained of hematuria, was treated three times with intravesical BCG administration. Since liver dysfunction was detected thereafter, he was admitted to our hospital. Three days after admission, he complained of dyspnea on exertion associated with severe hypoxemia, as well as abnormal findings on chest X-ray, i.e. extensive bilateral lung densities. We performed bronchoscopic examination and obtained bronchoalveolar lavage fluid (BALF) and lung biopsy specimens (TBLB). In the BALF, a marked increase in the total cell number, particularly lymphocytes with a high CD4/CD8 ratio was noted. TBLB specimens revealed the lesions to be numerous non-caseating granulomas. We failed to obtain definite evidence of BCG in the sputum, urine, blood, and BALF. Instead, we found that a lymphocyte stimulation test for BCG (DLST) was strongly positive. Based on these findings, severe interstitial pneumonia probably induced by hypersensitivity against BCG, was diagnosed. Anti-tuberculous agents, and steroid-pulse therapy followed by oral administration of relatively low dose of steroid ameliorated the abnormal conditions, including chest X-ray film findings and hypoxemia. The population of lymphocytes and CD4/CD8 ratio in the BALF were reduced as well. Serious interstitial pneumonia was induced by the intravesical administration of BCG, which resulted in transitional changes in the BALF cell component.

Alterations of insulin and glucagon secretion from the perfused pancreas before, at the onset and after the development of diabetes in male Otsuka Long-Evans Tokushima Fatty (OLETF) rats

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an obese non-insulin dependent diabetes mellitus (NIDDM) model of an inbred strain. In this study, basal (2.8 mM glucose) insulin and glucagon and their responses to glucose (16.7 mM) were examined at the age of 9 weeks (n = 3) before the onset of diabetes, at 23 weeks (n = 6) at the onset of diabetes, and at 48 weeks (n = 5) after the development of diabetes by pancreatic perfusion. In Long-Evans Tokushima Otsuka (LETO, control) rats, insulin responses to glucose showed a biphasic pattern at all three ages, while in OLETF rats, basal insulin concentrations were significantly increased compared to those in controls at the age of 9 and 48 weeks. Insulin responses to glucose showed no difference from controls at 9 and 23 weeks, however, at 48 weeks the response was significantly decreased. In controls, high basal glucagon concentrations showed significant decrease in response to glucose at all ages. In OLETF rats, basal glucagon concentrations showed significant decrease compared to those in control rats at 23 and 48 weeks. Glucagon response to glucose significantly decreased at 9 and 23 weeks, but at 48 weeks there was no change in concentration in response to glucose. Pancreatic insulin content was lower at 48 weeks in OLETF rats than in LETO rats, although no differences were observed at other ages. There were no significant differences in pancreatic glucagon content between the two groups at any age. Morphologically, in OLETF rats the number of pancreatic B cells were decreased and A cells migrated into the center of islets at 48 weeks. The results suggested that one of the causes of diabetes in OLETF rats is impaired insulin response to glucose.

The human DnaJ homologue dj2 facilitates mitochondrial protein import and luciferase refolding

DnaJ homologues function in cooperation with hsp70 family members in various cellular processes including intracellular protein trafficking and folding. Three human DnaJ homologues present in the cytosol have been identified: dj1 (hsp40/hdj-1), dj2 (HSDJ/hdj-2), and neuronal tissue-specific hsj1. dj1 is thought to be engaged in folding of nascent polypeptides, whereas functions of the other DnaJ homologues remain to be elucidated. To investigate roles of dj2 and dj1, we developed a system of chaperone depletion from and readdition to rabbit reticulocyte lysates. Using this system, we found that heat shock cognate 70 protein (hsc70) and dj2, but not dj1, are involved in mitochondrial import of preornithine transcarbamylase. Bacterial DnaJ could replace mammalian dj2 in mitochondrial protein import. We also tested the effects of these DnaJ homologues on folding of guanidine-denatured firefly luciferase. Unexpectedly, dj2, but not dj1, together with hsc70 refolded the protein efficiently. We propose that dj2 is the functional partner DnaJ homologue of hsc70 in the mammalian cytosol. Bacterial DnaJ protein could replace mammalian dj2 in the refolding of luciferase. Thus, the cytosolic chaperone system for mitochondrial protein import and for protein folding is highly conserved, involving DnaK and DnaJ in bacteria, Ssa1-4p and Ydj1p in yeast, and hsc70 and dj2 in mammals.

[Gastroesophageal reflux and airway disease]

Gastroesophageal reflux may cause a variety of airway diseases such as asthma, aspiration pneumonia, chronic bronchitis, posterior laryngitis, and ulceration or polyp formation on the vocal cords. Among these asthma seems most common and important clinically. Reflux not only may trigger and aggravate an episode of airway obstruction but also may contribute to nocturnal symptoms. Both clinical and experimental observations suggest that the pathogenetic mechanism may be a vagal reflux following stimulation of lower esophageal receptors and/or microaspiration of gastric acid into the trachea. Diagnosis is usually based on clinical history of asthma and symptoms of gastroesophageal reflux, but in some cases, diagnostic tests such as 24-hour esophageal pH monitoring may be necessary. General measures to avoid reflux and an H2-receptor antagonist together with supportive gastric medications may be the standard treatment. If symptoms persist, proton pump inhibitor may be helpful. Antireflux surgery may provide long-term improvements. Although surgical treatment is indicated only in patients with intractable esophagitis at present, it may be used more commonly through a laparoscopic approach in the near future.

Visualization of mitochondria with green fluorescent protein in cultured fibroblasts from patients with mitochondrial diseases

cDNAs for green fluorescent protein (GFP) and for a GFP fusion protein containing the presequence of human ornithine transcarbamylase (pOTC-GFP) were transfected into cultured human fibroblasts. GFP cDNA gave diffuse fluorescence throughout the cytoplasm and the nucleus, whereas pOTC-GFP cDNA gave mitochondria-associated fluorescence. Fluorescent mitochondrial structures could be classified into five patterns: thread-like mitochondria, fine thread-like ones, rod-like ones, granular ones, and granular ones with weak cytosolic fluorescence. pOTC-GFP mutants resulted in a loss of mitochondrial fluorescence and an appearance of weak fluorescence throughout the cytoplasm. pOTC-GFP cDNA was transfected into fibroblasts from patients with various mitochondrial diseases. Higher ratios of fibroblasts with granular mitochondria and those with fine thread-like ones were observed in a patient with Reye's syndrome and a patient with Kearns-Sayre syndrome. Weak cytosolic fluorescence was sometimes observed in fibroblasts from these patients. This method will be useful to analyze mitochondrial structural alterations and disorders of mitochondrial protein import.

A non-MHC locus essential for autoimmune type I diabetes in the Komeda Diabetes-Prone rat

The Long-Evans Tokushima Lean (LETL) rat, characterized by rapid onset of insulin-dependent (type I) diabetes mellitus (IDDM), no sex difference in the incidence of IDDM, autoimmune destruction of pancreatic beta cells, and no significant T cell lymphopenia, is a desirable animal model for human IDDM. We have established a diabetes-prone substrain of the LETL rat, named Komeda Diabetes-Prone (KDP) rat, showing a 100% development of moderate to severe insulitis within 220 d of age. The cumulative frequency of IDDM was 70% at 120 d of age, and reached 82% within 220 d of age. Here, we performed the first genome-wide scan for non-MHC IDDM susceptibility genes in this strain. The analysis of three crosses has led to the revelation of a major IDDM susceptibility gene, termed Iddm/kdp1, on rat chromosome (Chr) 11. Homozygosity for the KDP allele at this locus is shown to be essential for the development of moderate to severe insulitis and the onset of IDDM. Comparative mapping suggests that the homologues of Iddm/ kdp1 are located on human Chr 3 and mouse Chr 16 and would therefore be different from previously reported IDDM susceptibility genes.

[Thoracoscopic unilateral fold plication method in lung volume reduction surgery for diffuse pulmonary emphysema]

We have devised a 'Fold Plication Method', which helps ensure safe and simple lung volume reduction surgery (LVRS) for pulmonary emphysema and prevent air leakage from pulmonary stumps, which is most crucial problem, in addition to postoperative interstitial pneumonia that is occasionally caused by the use of the bovine pericardium. We performed LVRS on seven patients with the disease, using this method and the thoracoscopic surgery, which is based on the 'Two Windows Method' we had previously developed. The operation was performed without observable bleeding within approximately one hour for all patients, who then recovered favorably.

Displacement of gold marker in immunoelectron microscopy of human respiratory cilia

Preembedding immunogold electron microscopy was performed to evaluate the position of outer arm dynein heavy chains in normal human respiratory cilia. Anti-dynein antibody (AD2), which is specific for sea urchin sperm flagellar dynein heavy chains, was used as primary antibody. Direct cross-sections of cilia were selected, and the distance between the center of a cilium and the center of a colloidal gold particle attached to the cilium (X) was measured. The distance between the center of a cilium and the farthest edge of an outer dynein arm of the cilium was measured by ordinary electron microscopy (Yo) and by immunoelectron microscopy (Yi). X was significantly longer than Yo and Yi. If it is assumed that the structure of respiratory cilia is dense and that antibodies are located at the outer side of the actual position of the heavy chains, then the average distance difference of approximately 90-120 A may represent the length of two conjugated antibodies. This length should be kept in mind when performing immunoelectron microscopy. The data suggest that AD2 recognizes the outer arm dynein heavy chains of normal human respiratory cilia.

Downmodulation of IL-8 receptors, type A and type B, on human lung neutrophils in vivo

We examined the expression of interleukin (IL)-8 receptors (Rs), type A (IL-8-RA) and type B (IL-8-RB), on peripheral blood and bronchoalveolar lavage (BAL) fluid neutrophils; we also examined IL-8 and other chemoattractants in the epithelial lining fluid (ELF) of patients with chronic lower respiratory tract infection (CLI) to elucidate the in vivo regulation of IL-8Rs. Neutrophils were stained with monoclonal antibodies specific for IL-8-RA and IL-8-RB. We detected higher levels of IL-8 (81.6 +/- 25.4 ng/ml, mean +/- SE), leukotriene (LT) B4, and IL-1 beta in the ELF of the CLI patients than in their serum (P < 0.05). The expression of IL-8Rs on BAL neutrophils was significantly lower than that on peripheral blood neutrophils (P < 0.01 for both). In vitro analysis showed that low-level IL-8 (50 ng/ml) alone did not affect IL-8R expression but that it was downregulated by high-level IL-8 (500 ng/ml) alone and by low-level IL-8 in combination with LTB4 or IL-1 beta. Staurosporine reduced the downmodulation by low-level IL-8 plus LTB4 or IL-1 beta but not by high-level IL-8 alone. We speculate that pulmonary IL-8-RA and IL-8-RB may have been downmodulated by the combined effect of local chemoattractants through, in part, a protein kinase C-dependent mechanism.