HTLV-I proviral DNA in umbilical cord blood of babies born to carrier mothers

Human T-lymphotropic virus type I (HTLV-I) in cord blood raises the possibility of intrauterine transmission as an alternative pathway to transmission via breast milk. However, none of 7 children with HTLV-I proviral DNA positive cord blood had seroconverted by 24-48 months. Contamination of cord blood by maternal blood was precluded on the basis of viral load and IgA concentration. Thus cord blood proviral DNA is not a hallmark of intrauterine infection. Moreover, none of the cord blood samples of 9 formula-fed children later confirmed to be infected was positive for HTLV-I, indicating that intrauterine infection is not a likely candidate as an alternative pathway.

Expression of human T lymphotropic virus type 1 (HTLV-1) tax/rex gene in fresh bronchoalveolar lavage cells of HTLV-1-infected individuals

Accumulating evidence has suggested the involvement of HTLV-1 in the inflammatory lesions of various organs, including the lung. However, the causal relationship between HTLV-1 and inflammatory responses in the organs remains to be elucidated. In order to evaluate the expression of HTLV-1 and its effects in the lung, we examined the expression of mRNA for the HTLV-1 tax/rex gene in fresh bronchoalveolar lavage cells (BALC) and peripheral blood mononuclear cells (PBMC) of 23 seropositive individuals, including six patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), by use of an improved method of reverse transcription-polymerase chain reaction (RT-PCR). The tax/rex mRNA was more frequently detected in BALC than in PBMC. All the HAM/TSP patients and eight of 17 carriers without neurological symptoms showed the expression of tax/rex mRNA in the BALC. IgM class antibodies to HTLV-1 were preferentially detected in sera of the tax/rex mRNA-positive individuals. The detection of tax/rex mRNA correlated closely with the presence of lymphocytosis accompanied by an elevated proportion of IL-2 receptor-bearing T cells in the BALC. Our findings indicate the crucial role of viral expression in the inflammatory response in the lung in HTLV-1-infected individuals.

Novel growth promoting activity with a wide target cell spectrum is present in extracts of various cell types

Cell extracts from a variety of cell lines, myeloid, T, B, mastocytoma, fibroblast, melanoma and breast carcinoma of human, mouse and guinea pig promoted the growth of a wide variety of cell types, namely human myeloid cells HL-60, human B cells Daudi, human melanoma cells A375-C6, mouse transformed-fibroblast cells L929, human myelomonocytic cells THP-1. Among them, the activities in extracts from U937, A375-C6 and Daudi were characterized because these extracts exhibited much more potent activity. These growth promoting activities were acid-labile, sensitive to 2-mercaptoethanol and to heat treatment at 50C or 70C for 5 min. The activities were also sensitive to proteases indicating the proteinous nature of these active entities. The molecular weight of activities from A375 and Daudi cells were estimated to be 100,000-150,000 daltons by gel filtration high performance liquid chromatography, while that from U937 cells was 60,000-70,000 daltons. The isoelectric point of these activities were 5.5-6.5.

Multiple peripheral pulmonary artery branch stenosis in a young Japanese girl with systemic hypertension

We present a 16-year-old girl with pulmonary hypertension due to multiple pulmonary artery obstructions and stenoses. Juvenile hypertension was complicated by 75 percent stenosis of the left renal artery. Similar pulmonary angiographic findings 1 year later and no sign of inflammation in the following year suggest that this condition is congenital in origin.

[Partial nuclear oculomotor nerve palsy, MLF syndrome, hallucinose pédonculaire due to midbrain infarction--a case report]

The authors report on a 62-year-old woman who suffered from partial nuclear oculomotor nerve palsy and the medial longitudinal fasciculus (MLF) syndrome caused by midbrain infarction. The lesion was confirmed to be in the mesencephalic tegmentum by axial sections acquired by magnetic resonance imaging (MRI). The lesion was located in the caudal region of the mesencephalic tegmentum by the sagittal MRI sections, and showed low signal intensity in T1-weighted images and high signal intensity in T2-weighted images. The patient exhibited bilateral ptosis due to the disturbance of caudal central nucleus and the supra-oculomotor area on both sides innervating the levator muscles of the upper eyelid. She also showed bilateral limitation of ocular adduction and supraduction; mild infraduction of the left eyeball; left monocular nystagmus; and disturbance of convergence, indicating partial involvement of the lateral somatic cell column innervating the muscles of the eyeball, the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) and the MLF. Furthermore, transient visual hallucinations similar to hallucinose pédonculaire were confirmed. We are not aware of any reports describing simultaneous occurrence of bilateral ptosis, MLF syndrome, and transient visual hallucinations similar to hallucinose pédonculaire in the same patient.

Intervention of maternal transmission of HTLV-1 in Nagasaki, Japan

Seroepidemiological and laboratory virological evidences strongly suggested that endemicity of HTLV-1 in Nagasaki Japan depends on maternal infant infections via breast milk. The most obvious way to prove this concept was an intervention study with refraining from breast-feeding by carrier mothers. Most infected babies seroconverted by the age of 12 months, which made it possible to diagnose the infection at the age of 12 months for the statistical purpose. Serology and PCR on both adults and children were consistent each other, suggesting the absence of seronegative carriers. The intervention study revealed that approximately 80% of maternal infection was prevented by refraining from breast feeding by carrier mothers. The remaining fraction of infections in formula-fed babies suggested an alternative infection pathway. Although intrauterine infections has been suggested by others to explain the PCR-positive cord blood samples. However, groups of cord blood-positive children and seroconverted children were distinct each other. Therefore, the presence of HTLV-1 provirus in the cord blood can not be a marker of intrauterine infection. Mothers who infected a child has approximately 10 times higher risk of another infection for the next baby than those who did not.

Two thyroid hormone response elements are present in the promoter of human thyroid hormone receptor beta 1

Autoregulation of the human thyroid hormone receptor beta 1 (hTR beta 1) promoter was assessed by chloramphenicol acetyltransferase and luciferase reporter assays of transient transfections into COS1 and GH3 cells, DNase I footprinting, and gel shift assays. A 5'-deletional analysis of the promoter showed that the region between -906 and -839 and the sequence from -438 to -130 were positively regulated by T3 in COS1 cells cotransfected with an hTR beta 1 expression vector. We also transfected deletion constructs into GH3 cells and showed similar effects of T3 on the trans-activation of the reporters. DNase I footprinting showed a protected inverted palindromic thyroid response element (TRE) at position -890 to -866 in the distal fragment and a direct repeat at position -190 to -166 in the proximal fragment, which were protected by TRs. Mutation of each TRE significantly decreased the trans-activation of the promoter by T3. Gel mobility shift assays showed both proximal and distal TREs formed a retarded band with hTR alpha 1 or hTR beta 1 expressed in COS1 cells and reticulocyte lysates. The bands formed on the distal TRE and the proximal TRE appear to be preferentially formed by a TR homodimer and a heterodimer, respectively. Furthermore, the band formed on the distal TRE disappeared after adding T3 but that on the proximal TRE did not. These results indicate that hTR beta 1 expression is directly regulated by hTR alpha 1, beta 1, and their ligand through two TREs. The different structure of the TREs in this promoter suggests their physiological role in transcriptional regulation may be different.

Enhanced high-resolution sagittal MRI of normal pineal glands

OBJECTIVE

Our goal was to determine the appearance and enhancement pattern of human pineal glands on MRI.

MATERIALS AND METHODS

High-resolution sagittal MR images (3 mm section thickness with an 18 cm field of view) obtained in 60 patients were retrospectively analyzed to determine the size and enhancement patterns of normal pineal glands following the intravenous injection of contrast medium.

RESULTS

Pineal glands were either solid (40%) or cystic (60%) with various enhancement patterns: diffuse (15%) and partially enhanced (25%) in solid and ring-like (20%) and peripherally partial (40%) in cystic. Their diameter exceeded 10 mm but was < 20 mm in five cases and resembled cystic pineal neoplasms. Two such cases were found to be histologically normal.

CONCLUSION

Information on the appearance and enhancement patterns of normal pineal glands on MR images can improve the accuracy of diagnosing space-occupying lesions in the pineal region and perhaps help to prevent unnecessary surgery.

Large left-to-right shunt through a small atrial septal defect produced by progressive aortic stenosis in the elderly--a case report

We present a 74-year-old female who showed a large left-to-right shunt through a small atrial septal defect presumably due to diastolic dysfunction of the left ventricle caused by the progression of aortic stenosis. Accordingly, elderly patients with even small atrial septal defect should be followed carefully, since diastolic dysfunction of the acquired left ventricular disorder could increase the left-to-right shunt.

[Special cloth futon-cover (Miroguard) as a protection against house dust mite exposure]

We studied the efficacy of a special cloth encasing (Microguard) in protecting against house dust mite exposure. We vaccumed dust from right or left half surface of a shiki-futon (Japanese style mattress). Then we encased the shiki-futon by a new special encasing, vaccumed dust from the other part of the shiki-futon and got a pair of dust samples. We had done the same of the same shiki-futon by a used special encasing (used for one and half years) for about 2 weeks later. We prepared 7 shiki-futons and collected 14 pair dust samples. We weighed the dust and measured the mite allergens with a monoclonal antibody to Dermatophagoides pteronissynius and Dermatophagoides farinae. The dust level was 1.0% of the control (no encasing) in the new encasing group and 2.0% of the control in the used encasing group. The Der I concentration was 2.5 micrograms/(g dust) in the new encasing group and 3.2 micrograms/(g dust) in the used encasing group. The Der II concentration was 1.6 micrograms/(g dust). The total amount of Der I was 0.1% of the control in the new encasing group and 0.5% of the control in the used encasing group. The total amount of Der II was 0.2% of the control in the new encasing group and 0.7% of the control in the used encasing group. We compared Der p and Der f levels in the dust samples which we assayed and found no significant differences either in Der I or in Der II allergen. We concluded that Microguard was a useful tool to avoid mite allergen exposure by reducing not only the concentration of mite allergens but also the amount of dust.

Bioassay for interleukin-1, interleukin-6, and tumor necrosis factor-like activities in canine sera

To measure interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-like activities in canine serum, bioassays were conducted using human melanoma A375S1, IL-6 dependent murine hybridoma MH60.BSF2, and WEHI 164 murine sarcoma subclone 28-4. Clinically normal adult beagles were experimentally induced endotoxic shock by an intravenous injection of lipopolysaccharide or local inflammation by an intramuscular injection of turpentine oil. IL-1-like activity was detected in sera from dogs with endotoxic shock. IL-6 and TNF-like activities were detected in sera from both dogs with endotoxic shock and local inflammation. IL-1-like activity in sera from the dogs with endotoxic shock declined after dilution with either medium or serum obtained before treatment (pre-serum), but the IL-1-like activity was maintained to a greater extent in samples diluted with pre-serum compared to those diluted with medium. TNF-like activity declined equally after dilution with either medium or pre-serum. On the other hand, IL-6-like activity was inhibited at low dilution. It was, therefore, necessary to dilute the serum samples to 1:180 from dogs with endotoxic shock or 1:60 from dogs with local inflammation, in order to minimize the effect of inhibitory factors on IL-6-like activity. IL-6-like activity was neutralized by monoclonal antibody against murine IL-6 receptors. TNF-like activity was neutralized by anti-mouse TNF alpha rabbit serum. However IL-1-like activity was not neutralized by either anti-mouse or anti-human IL-1 rabbit serum.

Activation of a cation conductance by acetic acid in taste cells isolated from the bullfrog

The ionic mechanism of the conductance activated by acetic acid was analyzed in isolated bullfrog taste cells under whole-cell voltage-clamp. Bath-application of acetic acid (pH 3.9-4.7) induced an inward current in about 80% of the taste cells. The current occurred in external 80 mmol l-1 Ba2+ and internal 100 mmol l-1 Cs+, which completely blocked the delayed outward K+ current. The concentration-response relationship for the acid-activated current was consistent with that of the gustatory neural response. Prolonged adaptation of the surface of the tongue to HCl prior to taste cell isolation decreased the acid-induced current to about 20% of the control value without decreasing NaCl-induced neural responses and voltage-activated Na+ currents. The results suggest that the transduction mechanism of the acid response might be different from that of the response to salt. The I-V relationship of the acid-induced response was nearly linear at membrane potentials between -80 and 80 mV. The acid-induced conductance was permeable to alkali metal and alkali earth metal ions. The permeability ratios were PCa:PBa:PSr:PNa:PCs = 1.87:1.17:0.73:0.99:1.00. The present study suggests that the acid-induced receptor current in bullfrog taste cells is generated by an increase in a cation conductance in the apical taste membrane.

Contents of lecithin and choline in crude drugs

The determination of lecithin and choline in crude drugs was established by a combination of high performance liquid chromatography (HPLC) with electrochemical detector (ECD) and enzyme reaction. Lecithin in crude drugs extracted with a mixture of chloroform-methanol (2:1) at room temperature was hydrolyzed by phospholipase D. The hydrolyzate was injected to HPLC, and choline was separated from impurities by reverse phase column. The choline was converted to betaine and hydrogen peroxide by passing through column packed with immobilized choline oxidase. This hydrogen peroxide was detected by ECD. The peak area of hydrogen peroxide derived from lecithin was proportional to the concentration of lecithin from 0.10 to 1.52 microgram/ml. Choline in crude drugs was extracted with ethanol under reflux and determined under the same HPLC conditions as lecithin. The peak area of hydrogen peroxide derived from choline was proportional to the concentration of choline from 0.01 to 0.45 microgram/ml. The contents of lecithin and choline in 31 kinds of crude drugs were determined by these established methods. The results showed that Cervi Parvum Cornu, Kokurozin, Foenigraeci Semen and Psoraleae Semen contained more lecithin than other crude drugs, while Angelicae Radix, Foenigraeci Semen, Psoraleae Semen, and especially Hippocampus were found to contain more choline than other crude drugs.

Changes in magnetic resonance images in human skeletal muscle after eccentric exercise

To investigate the time-course of changes in transverse relaxation time (T2) and cross-sectional area (CSA) of the quadriceps muscle after a single session of eccentric exercise, magnetic resonance imaging was performed on six healthy male volunteers before and at 0, 7, 15, 20, 30 and 60 min and 12, 24, 36, 48, 72 and 168 h after exercise. Although there was almost no muscle soreness immediately after exercise, it started to increase 1 day after, peaking 1-2 days after the exercise (P < 0.01). Immediately after exercise, T2 increased significantly in the rectus femoris, vastus lateralis and intermedius muscles (P < 0.05) and decreased quickly continuing until 60 min after exercise. At and after the 12th h, a significant increase was perceived again in the T2 values of the vastus lateralis and intermedius muscles (P < 0.01) [maximum 9.3 (SEM 2.8)% and 10.9 (SEM 2.2)%, respectively]. The maximal values were exhibited at 24-36 h after exercise. In contrast, the rectus femoris muscle showed no delayed-stage increase. Also, in CSA, an increase after 12 h was observed in addition to the one immediately after exercise in the vastus lateralis, intermedius and medialis and quadriceps muscles as a whole (P < 0.01), reaching the maximal values at 12-24 h after exercise. The plasma creatine kinase activity remained unchanged up to 24 h after and then increased significantly 48 h after exercise (P < 0.05). Beginning 12 h after exercise, the subjects whose T2 and CSA increased less than the others displayed a faster decrease in muscle soreness.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of long-term endurance training on left ventricular dimensions and function in female distance runners]

Ultrasoundcardiogram (UCG) was measured to evaluate the effects of 2 years of endurance training on left ventricular dimensions and function in 3 female collegiate runners (mean age 19.7 years). All subjects had had an experience in endurance training as athletes and underwent the endurance training at the college for two years. Training consisted mainly of about 2 hours of running, 3 to 4 days a week. Training effects were found as measured by a 5000m-run pretraining (mean 19: 40.3 min) and post-training (mean 18: 49.3 min). The average increase in maximal oxygen uptake (VO2max/kg) after training was 9.4% (P < 0.05). UCG's dimensional variables such as LVDd, LVPWT and IVST in the post-training period did not reveal any increase. However, LVDs as a cardiac dimension showed a tendency to decrease, and functional variables such as SV, EF, FS showed a tendency to increase. This functional improvement appeared to be due to a decrease in LVDs. From these results, it is likely that the endurance training prior to this study might have helped an effective adaptation in their cardiac dimensions. Thus, we suggest that prior to this study cardiac dimensions had extended and enlarged to a certain extent, and then cardiac function might be improved as the subsequent physiological phenomenon.

Evaluation of the ontogeny of thyroid hormone receptor isotypes in rat brain and liver using an immunohistochemical technique

We performed an immunohistochemical study on rat brain and liver during fetal and neonatal life using rabbit antipeptide polyclonal antibodies able to recognize each thyroid hormone receptor (TR) isoform. The expression of TR alpha-1, alpha-2 and beta-1 proteins from 14 days of gestation to 21 days after birth was evaluated. Frozen tissues from 14 (F14), 17 (F17) and 21 (F21)-day-old fetuses and from 5 (N5), 16 (N16) and 21 (N21)-day old newborn rats were stained with anti-TR antibodies using an avidin-biotin-peroxidase system. The antipeptide antibodies utilized in the present study were characterized previously: alpha-144 antibody recognizes both TR alpha-1 and alpha-2; alpha-2-431 antibody is specific for TR variant alpha-2, and beta-62 antibody specifically reacts with the TR beta-1 isoform. The expression of TR alpha-1 was deduced by comparing the staining obtained with alpha-144 and alpha-2-431 antibodies. We demonstrated that each TR isoform is expressed in rat brain from 14 days of gestation and that the alpha isoform was predominant in the early stage. The three TR isoforms were expressed in both neural cell nuclei and in glial cell nuclei. As far as the liver is concerned, at F14 the expression of TR isoforms was weaker in hepatocytes when, on the contrary, TR alpha was clearly detected in hematopoietic cells. The expression of TRs in hepatocytes becomes evident later. The data that we obtained, although not quantitative, emphasize the presence of each TR isoform in brain and liver from 14 days of fetal rat life.

Apatite coated on organic polymers by biomimetic process: improvement in its adhesion to substrate by NaOH treatment

A dense, uniform and highly biologically active bone-like apatite layer can be formed in arbitrary thickness on any kind and shape of solid substrate surface by the following biomimetic method at ordinary temperature and pressure. First, a substrate is set in contact with particles of bioactive CaO SiO2 based glass soaked in a simulated body fluid (SBF) with inorganic ion concentrations nearly equal to those of human blood plasma. Second, the substrate is soaked in another solution with ion concentrations 1.5 times those of SBF (1.5 SBF). In the present study, organic polymer substrates treated with 5 M NaOH solution were subjected to the above mentioned biomimetic process. The induction periods for the apatite nucleation on polyethyleneterephthalate (PET), polymethylmethacrylate (PMMA), polyamide 6 (PA6), and polyethersulfone (PESF) substrates were reduced from 24 to 12 h with the NaOH treatment. The adhesive strength of the formed apatite layer were increased from 3.5 to 8.6 MPa, from 1.1 to 3.4 MPa, and from 0.6 to 5.3 MPa with the NaOH treatment, for PET, PMMA, and PA 6, respectively. It was assumed that highly polar groups, such as carboxyl and sulfinyl ones formed by the hydrolysis of an ester group on PET and PMMA and of an amide group on PA 6, or of a sulfonyl group on PESF with the NaOH treatment, attached a large number of hydrated silica dissolved from the glass particles, to accelerate the apatite nucleation, and also to form a strong bond with the apatite. The apatite-organic polymer composites thus obtained are expected to be useful as bone-repairing as well as soft tissue-repairing materials.

[Allergic characteristics of bronchial asthma in the elderly]

Allergic characteristics were investigated in asthma patients older than 60 years of age. Among these asthmatic patients: 1. About 37% showed negative immediate skin response to all antigen extracts tested. 2. The frequency of positive immediate skin response to house dust, house dust mite, Japanese cedar and Alternaria decreased with aging. 3. There was no difference in the frequency of positive immediate skin response to Candida antigen among patients in different age groups. Candida was the antigen that most frequently produced positive immediate skin response among the patients over 50 years old. 4. There was no difference between skin-positive elderly asthmatics and young asthmatics in the frequency of positive IgE antibody titer, bronchial response, conjunctival response and histamine release from peripheral leukocytes by specific antigens. These findings show that atopic asthmatics are less frequently found in elderly asthmatic patients than in young patients. Nevertheless, there is no difference in the characteristics of atopy, except in the response to Candida antigen.

Fast-neutron radiotherapy of nonsmall cell-carcinoma of the lung

To determine the efficacy of fast neutron (FN) for the treatment of non-small cell lung cancer, 112 patients with histologically proven adenocarcinoma or squamous cell carcinoma at a limited stage were studied to evaluate local control and survival, after treatment with either FNs or photons alone. The local control rate of adenocarcinoma in FN-treated patients attained 50%, which was significantly higher than that (<10%) of squamous cell carcinoma in FN-treated patients or that of both histological types of carcinoma in patients treated with photons alone. In accordance with this, the 5-year survival rate for the FN-treated patients with adenocarcinoma was significantly higher than that for FN-treated patients with squamous cell carcinoma or that for photon-treated patients with both histological types of disease. The present study clearly suggests the usefulness of FN in the treatment of adenocarcinoma of the lung, though it was a non-randomized trial.

Inhibition of salt-induced gustatory responses in the frog (Rana catesbeiana) by 5'-GMP

Millimolar concentration of sodium 5'-guanylate (5'-GMP), a 'umami' substance, inhibited salt-induced gustatory neural responses, particularly tonic components, of the bullfrog when the tongue was adapted to a low salt (5 mM NaCl) solution but not when adapted to normal saline that contained 115 mM NaCl. The result suggests that 5'-GMP is a modulator of adaptation process in salt response in the bullfrog taste system.

Amplification and detection of a single molecule of human immunodeficiency virus RNA

Detection of plasma viremia in human immunodeficiency virus type 1 (HIV-1)-infected people is indispensable for the diagnosis of seronegative infection as well as for the evaluation of virus activities in vivo. The direct detection of HIV-1 RNA in circulation has been performed by means of reverse transcription followed by polymerase chain reaction (RT-PCR). As an attempt to establish a highly sensitive assay, we evaluated the effects of two-step amplification with nested primers and double priming of reverse transcription on the sensitivity of RT-PCR. The sensitivity of two-step amplification was 100 times higher than that of one-step amplification. The double priming of reverse transcription further increased the sensitivity of the following two-step amplification 100 times, which appeared to be enough to detect HIV-1 RNA from as little as a 2.2 x 10(-4) TCID50 unit equivalent of culture supernatant of HIV-1-infected cells and a single molecule of HIV-1 gag complementary RNA synthesized by in vitro transcription. By use of this most sensitive assay, we successfully detected HIV-1 RNA in serum or plasma from all 22 patients with acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC) and 13 out of 14 untreated asymptomatic carriers. Of 43 asymptomatic carriers under the treatment with interferon-alpha or azidothymidine, 17 cases showed negative results, indicating that the virus activity was suppressed by the therapeutics. We also noted the inhibitory effect of heparin on RT-PCR.

[A case of transient vertical gaze palsy following right thalamic and midbrain infarction]

The authors report a 71-year-old male who suffered from vertical gaze palsy due to infarction localized on MRI in the right midbrain. Vertical gaze palsy was observed 1 hour after the onset of his stroke. Upgaze palsy was noted the following day. Four days later, the disturbances of ocular movement disappeared. T2 weighted MR imaging showed a high signal intensity lesion, which was localized in the right side of the thalamo-mesencephalic portion. However, since the vertical gaze palsy appeared only transiently for a short time in the initial stage and since the level of consciousness decreased during that time, it was suggested that there was a bilateral functional disorder caused by mild edema, etc., in the hyperacute stage, which was not demonstrated on MRI. This disorder had been overlooked either because the duration of the vertical gaze palsy due to the unilateral lesion was very short, i.e. improvement was seen 4 days after onset, or the lesion was not clearly delineated in a CT scan of the head. It appeared possible that this sign might not be very rare if careful observations are performed in the hyperacute stage of midbrain infarction.

Mast cells are essential for the full development of silica-induced pulmonary inflammation: a study with mast cell-deficient mice

Silicosis provides a good model for chronic interstitial pulmonary inflammation. In order to clarify the role of mast cells in the development of interstitial lung diseases, silica suspension was transnasally administered to mast cell-deficient mice (WBB6F1-W/Wv) and their mast cell-intact littermates (WBB6F1(-)+/+) as well as to normal mice (C57BL/6). Histologic examinations and analyses of bronchoalveolar lavage fluid (BALF) components indicated that silica instillation induces less severe lung lesions in mast cell-deficient mice than in mast cell-intact mice. BALF neutrophilia was prominent in mast cell-intact mice, but mast cell-deficient mice developed significantly milder BALF neutrophilia. An increase in the number of lung mast cells was observed in mast cell-intact mice. To further prove the involvement of mast cells, bone marrow-derived cultured mast cells from +/+ mice were adoptively transferred to mast cell-deficient mice. These mast cell-reconstituted mice developed more severe pulmonary lesions than did the mast cell-deficient mice; the severity of the lesions was similar to that in mast cell-intact mice. In addition, BALF neutrophilia was elicited by mast cell reconstitution. A significant number of mast cells was found in the lungs of mast cell-reconstituted mice when silica was administered. These results suggest the involvement of mast cells in the development of silicosis and implicate interactions between mast cells and neutrophils in the pathogenesis of this disorder.

Non-selective cation channel in bullfrog taste cell membrane

Using single channel recordings of the patch clamp method, we found first that cation channels were present in the bullfrog taste cell membranes. These channels were widely distributed over the taste cell membrane. The conductance examined with inside-out patches was 30.7 +/- 5.7 pS (mean +/- S.D., n = 13). The permeability ratio of the cation channel to monovalent cations was PK:PCS:PNa = 1.18:1.00:0.70, indicating that the channels are non-selective.

Kinetics of infectivity are dissociated from PrP accumulation in salivary glands of Creutzfeldt-Jakob disease agent-inoculated mice

The protease-resistant isoform of prion protein (PrP) has been implicated in the pathogenesis and transmission of Creutzfeldt-Jakob disease (CJD), scrapie and other related diseases, but the relationship between the infectious agent and PrP awaits elucidation. In the present study, we have examined levels of infectivity together with accumulation of the protease-resistant form of PrP (PrPCJD) in various tissues of CJD agent-inoculated mice. Accumulation of PrPCJD occurred only in tissues, including brain, salivary gland and spleen, in which infectivity was readily detectable throughout the course of the experiment. The brain showed the highest levels of both infectivity and PrPCJD accumulation, with well correlated kinetics. On the other hand, the high titres of infectivity detected in salivary gland and spleen early after inoculation of the agent were obviously distinguishable from PrPCJD. Furthermore, in the salivary gland, the kinetics of infectivity and the accumulation of PrPCJD reversed; infectivity declined as PrPCJD accumulated in the tissue. Our findings indicate that PrPCJD accumulation is associated with replication of the agent; however, PrPCJD is unlikely to be the agent itself.