Human arylhydrocarbon receptor: functional expression and chromosomal assignment to 7p21

We isolated the human arylhydrocarbon receptor (AhR) cDNA from a human lung cDNA library, by using mouse AhR cDNA as a labeled probe. The nucleotide sequence of cloned human AhR cDNA is identical to the previously reported human AhR sequence [Dolwick et al. (1993), Mol. Pharmacol. 44, 911-917] from cell line HepG2. The overall amino acid identity with mouse AhR from cell line Hepa-1 is 72.5%. The human AhR expressed either in COS-7 cells or in a reticulocyte lysate in vitro translation system showed specific dioxin-binding activity and Arnt-dependent DNA-binding activity. Chromosomal localization of the AhR gene was determined to be chromosome 7p21 by fluorescent in situ hybridization and DNA blot hybridization using 23 human x mouse or Chinese hamster hybrid cell DNAs.

Increased plasma osmolality stimulates peripheral and central vasopressin release in male and female rats

It has been demonstrated that the neurohypophysial hormones can be released intrahypothalamically by the paraventricular (PVN) and supraoptic nuclei. The present experiments were undertaken to determine whether a physiological stimulus for vasopressin release, increased plasma osmolality, will stimulate the release of vasopressin by the PVN into the surrounding interstitial fluid, and whether the responses are affected by gender. Intravenous infusion of 2.5 M NaCl for 60 min (0.1 ml.kg-1.min-1) in conscious rats resulted in an increased vasopressin concentration in the dialysate from a microdialysis probe adjacent to the PVN. This response was greater in nonestrous females than in males. On the other hand, the rise in the plasma vasopressin concentration was greater in males than in nonestrous females. Mean arterial blood pressure increased and heart rate decreased, but these responses were not affected by gender. The role of centrally released vasopressin in the control of the peripheral release of vasopressin is conjectural, but both responses may be modulated by the gonadal steroid hormones.

Hemorrhage-induced vasopressin release in the paraventricular nucleus measured by in vivo microdialysis

Experiments were carried out, using the technique of in vivo microdialysis in conscious rats, to determine whether hemorrhage, a potent stimulus for the release of vasopressin from the posterior pituitary into the circulation, would also result in a local release of vasopressin from the paraventricular nucleus (PVN), and whether this release is affected by gender. Male and non-estrous female rats were prepared with a microdialysis probe adjacent to the PVN and femoral arterial and venous catheters the day before the experiment. On the day of the experiment, rats was bled either 20% or 30% of blood volume. The concentration of vasopressin in the dialysate increased significantly in the males following both hemorrhages and in the females following the 30% hemorrhage. There were no statistically significant differences in the post-hemorrhage dialysate vasopressin concentration with respect to either gender or magnitude of the hemorrhage. The plasma vasopressin concentration increased markedly in response to the hemorrhage and this response was greater in females following the 30% hemorrhage. There were no gender differences in the reduction in arterial pressure following either hemorrhage. It is concluded that physiological stimuli for the release of vasopressin into the circulation also result in intrahypothalamic release of this hormone.

Dimerization characteristics of the DNA- and steroid-binding domains of the androgen receptor

The DNA-binding domain (DBD) of the androgen, mineralocorticoid, and glucocorticoid receptors and the steroid-binding domain (SBD) of the androgen receptor (AR) were expressed separately as fusion proteins with glutathione-S-transferase (GST) in Escherichia coli. Native polyacrylamide gel electrophoresis and gel exclusion HPLC demonstrated that the GST-ARDBD fusion protein was present as a dimer. On the other hand, the GST-ARSBD fusion protein formed a high-molecular weight oligomer, which seemed to be formed by two separate interactions, i.e. GST-GST and ARSBD-ARSBD between the fusion molecules. These findings strongly suggest that ARSBD has a potent ability to form a homodimer and that ARDBD does not. GST-ARDBD specifically interacted with the glucocorticoid response elements of the mouse mammary tumor virus long terminal repeat (GREMMTV). Cleavage of the fusion protein by thrombin abolished the binding, while the nonspecific DNA-cellulose binding ability was retained. Therefore, the dimeric configuration of GST-ARDBD, even if accomplished through the interaction with the GST moiety, is needed for high-affinity binding to the response element. The binding of GST-ARDBD to GREMMTV was strongly competed by the glucocorticoid response element of rat tyrosine aminotransferase gene, followed by the androgen response element of the rat probasin gene. A palindromic thyroid response element showed no competition. Unexpectedly, no apparent different in the binding affinity to these response elements was observed among the DBDs of androgen, mineralocorticoid and glucocorticoid receptors.

Structural studies of condensation products of biogenic amines as inhibitors of tryptophan hydroxylase

The effects of condensation products of dopamine and indoleamines on the activity of tryptophan hydroxylase (TPH) were evaluated to determine the structures associated with modulation of this enzyme activity. The compounds having a catechol structure, such as 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, markedly inhibited the activity of the enzyme prepared from the rat brain. The inhibition was non-competitive in terms of both the biopterin cofactor and the substrate L-tryptophan. Substitution on the one or two positions of catechol isoquinolines did not affect the inhibitory activity towards TPH. Among these compounds, a charged substance, 1,2[N]-dimethyl-6,7-dihydroxy-isoquinolinium ion, was an extremely potent inhibitor; the Ki values were 0.88 +/- 0.17 and 0.64 +/- 0.08 microM (mean +/- S.D.) in terms of the substrate and cofactor, respectively. By contrast, the condensation products of tryptophan and tryptamine with acetaldehyde scarcely affected TPH activities. 1-Methyl-1,2,3,4-tetrahydroisoquinoline, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium ion (MPP+) were almost inactive. These results indicated that the catechol structure recognized and combined with TPH at a binding site different from that of the substrate or cofactor and the positive charge on the dopamine-derived substance enhanced the affinity to TPH. The selective inhibition of TPH by dopamine-derived catechol isoquinolines was discussed in relationship to the interactions between catecholamines, indoleamines and their metabolites in the brain under physiological and pathological conditions.

Inhibition of tryptophan hydroxylase by dopamine and the precursor amino acids

Effects of dopamine and its precursor amino acids on the activity of tryptophan hydroxylase were examined. They inhibited the enzyme activity prepared from mastocytoma cells in terms of the biopterin cofactor and the substrate L-tryptophan. In relation to the biopterin, tryptophan hydroxylase was found to have two different kinetics, and dopamine inhibited the activity in a non-competitive way to both the components. Dopamine had the highest affinity to the enzyme, followed by L-DOPA and L-tyrosine, while D-tyrosine did not inhibit the activity. In terms of L-tryptophan, L-tyrosine, L-DOPA and dopamine inhibited the enzyme non-competitively and their affinity to the enzyme was in this order. These results indicate that the indoleamine metabolism may be regulated by catecholamines and their related amino acids in the brain.

Co-expression of epidermal growth factor-receptor and c-erb B-2 proto-oncogene product in human salivary-gland adenocarcinoma cell line HSG and the implications for HSG cell autocrine growth

The autonomous proliferation of HSG cells is mediated by an autocrine growth factor, a 46K epidermal growth factor (EGF)-like molecule. The receptor for this molecule was investigated. Immunoprecipitation and immunoblotting revealed the expression of two possible receptor molecules, EGF-R and p185erbB-2, in HSG cells. Northern blotting also revealed the co-expression of 5.6-kb EGF-R mRNA and 4.6-kb c-erb B-2 mRNA. When the purified EGF-like molecule was added to the cultures, EGF-R but not p185erbB-2 was autophosphorylated. These results suggest that, although both EGF-R and p185erbB-2 are co-expressed in HSG cells, the EGF-R is the genuine receptor for the EGF-like molecule. However, there is a possibility that p185erB-2 is involved in the signal transduction system. This possibility was examined by using specific antibodies to human EGF-R (hEGF-R), p185erbB-2, and EGF to inhibit the functions of these molecules. Addition of these three antibodies to the cultures inhibited the growth of HSG cells. The antibodies to EGF-R and p185erbB-2 also caused morphological changes such as disturbances of the plasma membrane, and some cell death. Surprisingly, the effect of the anti-p185erbB-2 antibody on growth inhibition and morphology was stronger than that of the anti-hEGF-R antibody. Thus, p185erB-2 expressed in HSG cells has an important function in the signal transduction of HSG cell growth.

Nested amplification of COL2A1 3' variable region in skeletal remains

We identified skeletal remains of a highly decomposed body by amplifying the COL2A1 3' variable region. We extracted degraded and contaminated DNA from teeth and bone fragments and amplified the hyper variable regions of COL2A1 by nested PCR. This method is 2,000 times more sensitive than the 27 cycle standard PCR. The sensitivity and specificity of the amplification was extremely improved using nested primer pairs. Using 47 cycles of total amplification by nested PCR, we were able to effectively amplify the target fragment. A total 47 cycles of dual PCR using one pair of primers was not as sensitive as nested PCR, which enabled us to amplify and detect the fragment from 5 pg of template DNA by agarose gel electrophoresis with ethidium bromide staining. We found that the hypersensitive nested PCR was suitable for the forensic identification of old, unidentifiable skeletal remains.

Association of HLA-DPB1*0501 with early-onset Graves' disease in Japanese

To investigate the association between HLA antigens and Graves' disease among Japanese, serologic typing and DPB1 genotyping using the PCR-RFLP method have been performed. HLA alleles of 106 patients with Graves' disease were determined, and the frequency of HLA-B46 was found to be significantly increased. Furthermore, the frequencies of HLA antigens were compared between two age groups: early-onset and late-onset patients (under and over 20 years, respectively). It was found that the frequency of DPB1*0501 (88.9%) was significantly increased (pc < 0.004) in the early-onset group as compared with the healthy controls (55.0%) but not in the late-onset group (60.7%). On the other hand, a significant increase of HLA-B46 was observed in the late-onset patients (pc < 0.0004). These results suggest that the genetic background of Japanese patients with early-onset Graves' disease is different from late-onset patients. Namely, the HLA-DP allele (DPB1*0501) and the HLA-B allele (B46) are primarily involved in the pathogenesis of early-onset and late-onset Graves' disease in Japanese, respectively.

[Effect of recombinant atrial natriuretic peptide (r-ANP) on ischemic and cyclosporine-induced kidney damage in rats]

Cyclosporine A (CYA) a new immunosuppressive drug, has greatly improved the outcome of solid graft transplantation. The nephrotoxicity of CYA, however, is a serious problem, and constitutes the major obstacle limiting the use of CYA as an immunosuppressive agent for renal transplantation. On the other hand, the newly described atrial natriuretic peptide (ANP) hormonal system in both humans and animals appears to play an important role in sodium and water excretion. The present study examined the nephrotoxicity of CYA and the effect of recombinant-ANP (r-ANP) on the damaged kidneys in three groups. Group 1 consisted of rats with 45 minutes warm ischemic left kidney and right nephrectomy [WI rats]; Group 2 consisted of WI rats with oral administration of CYA (100mg/kg/day) for 2 weeks [WI+CYA rats]; Group 3 consisted of WI+CYA rats with intraperitoneal administration of r-ANP (10ng/kg/day) for 2 weeks. Group 2 had lower glomerular filtration rates (GFR) and renal plasma flow (RPF) than Group 1, but Group 3 had significantly higher GFR and RPF than Group 2. Additionally, in order to demonstrate the change in renal viability among the three groups, the adenosine triphosphoric acid level (ATP) and adenylate energy charge ratio (EC) of renal parenchymal tissue were measured by high performance liquid chromatography (HPLC). Group 2 had lower ATP and EC than Group 1, and Group 3 had higher ATP and EC than Group 2. The results of this study suggest that r-ANP is efficacious on rat kidney damage induced by CYA and WIT.

[Studies on aspoxicillin for its transfer to the skin]

To evaluate the usefulness of aspoxicillin (ASPC) in the field of plastic and reconstructive surgery, we examined its transfer to the skin. 1. After intravenous drip infusion of ASPC for 1 hour at a dose of 2 g in 13 adults and at 1 g in 2 children, the mean serum ASPC concentration 1 hour after termination of the infusion was 70.46 +/- 28.05 micrograms/ml. The mean concentration in the skin tissue 1 hour after infusion in 15 patients was 32.45 +/- 18.47 micrograms/g. The rate of transfer to the skin 1 hour after infusion in the 15 patients was 52.9 +/- 29.7%. 2. The ASPC concentrations in skin tissues and the rates of its transfer to the skin did not differ significantly between 5 patients with facial surgery and 10 with surgery in the trunk or limbs. 3. To prevent postoperative infections, ASPC was intravenously drip infused twice daily for 2 approximately 3 days after operation at a dose of 2 g in adults and 1 g in children. No postoperative infection occurred in any patient, suggesting the effectiveness of this drug. In addition, no side effects or abnormalities in clinical examination values were observed.

[Two cases of MERRF (myoclonus epilepsy associated with ragged red fibers) showing different clinical features in the same family]

A 73-year-old woman (patient 1) developed progressive mental deterioration at age 63, and seizures at age 70. On examination, she showed severe dementia, tonic clonic convulsion, hypotonia and muscular wasting. There was neither myoclonus nor cerebellar ataxia. Brain CT revealed a low density area in the right occipital lobe. A 44-year-old man (son of the patient 1) developed unsteady gait at age 15, muscle twitching at age 18 and then noticed speech disturbance at age 35. He had no history of convulsive seizure. Neurological examination showed cerebellar ataxia, myoclonus in the extremities and mild muscular weakness. His intelligence was normal. Brain CT showed moderate atrophy of the pons and the cerebellum. Both cases showed the same mitochondrial DNA mutation as reported previously in patients with MERRF. However, the clinical features, the age of onset and the brain CT findings were totally different between these 2 cases. In the progress of mitochondrial genetic analysis, atypical forms in MERRF like the patient 1 would increase in number, and the wide variation of clinical symptoms should be considered.

Role of vasopressin, the renin-angiotensin system and sex in Dahl salt-sensitive hypertension

OBJECTIVE

To determine the roles of vasopressin, the renin-angiotensin system and sex in the pathogenesis of salt-sensitive hypertension in the Dahl rat.

DESIGN

The effects of 12 days' treatment with a non-peptide, orally effective V1 antagonist (OPC-21,268) and captopril, individually or together, were compared in male and female Dahl salt-sensitive rats after 10 days on a high-salt diet.

METHODS

OPC-21,268 was given in the food, and captopril was administered with osmotic pumps implanted subcutaneously.

RESULTS

Systolic blood pressure (SBP) reached a higher level in untreated males than in untreated females. V1 blockade in males prevented any further increase in SBP during the first week of treatment, but SBP rose thereafter towards the levels found in the untreated males. In females OPC-21,268 had no effect. In males captopril prevented any further increase in SBP. There was no effect of captopril in females during the first week of treatment, but SBP fell to pretreatment levels during the second week. Combined treatment with OPC-21,268 and captopril in males had a smaller antihypertensive effect than either drug alone. In females combined treatment prevented any further increase in SBP.

CONCLUSIONS

These findings suggest that both vasopressin and the renin-angiotensin system contribute to the pathogenesis of Dahl salt-sensitive hypertension, but that other factors, possibly including the sympathetic nervous system, are also involved. Sex also affects the severity of this form of hypertension and influences the relative roles of vasopressin and the renin-angiotensin system. It is likely that the gonadal steroid hormones modulate the activity of the pathogenetic factors in this form of hypertension at a central or peripheral level.

[Effect of palonidipine hydrochloride (TC-81), a new dihydropyridine derivative, on various myocardial ischemic models]

The antianginal effects of palonidipine, a novel 1,4-dihydropyridine derivative, and nifedipine on various myocardial ischemic models were compared. (1) Palonidipine at 0.5 mg/kg, p.o. significantly inhibited vasopressin-induced ST depression of ECG in Donryu rats. This activity was about 5 times more potent than that of nifedipine and was long-lasting. (2) Palonidipine at 1 mg/kg, i.d. significantly inhibited ST depression induced by isoproterenol in Wistar rats. This activity of TC-81 was more potent than that of nifedipine. (3) Palonidipine at 3 micrograms/kg, i.v. produced an increase in regional myocardial tissue blood flow in the ischemic region of chronic coronary artery occluded dogs. (4) In isolated dog coronary artery, palonidipine at a concentration of 10(-10) M or greater inhibited the amplitude of 3,4-DAP-induced cyclic contractions in a concentration-dependent manner. This activity was 10-30 times more potent than that of nifedipine. (5) An intracoronary injection of endothelin (30 pmol/kg) reduced the coronary blood flow, subepicardial tissue blood flow, and subepicardial pH in anesthetized dogs. The ST elevation of ECG over 0.1 mV also occurred in 8 of 10 cases. In all the cases, ventricular extrasystoles were noted, and 9 out of 10 animals died. Pretreatment with palonidipine (3 micrograms/kg, i.v.) inhibited endothelin-induced ischemic changes, with a potency greater than that of nifedipine. These results suggest that palonidipine may be useful for the therapy of angina-pectoris.

Cell-mediated immune-pancytopenia complicating primary Sjögren's syndrome

A 64-year-old woman with mild bilateral parotid gland swelling and bilateral lower extremity purpura was admitted for evaluation of xerostomia and pancytopenia. The patient had an increased erythrocyte sedimentation rate, pancytopenia, and positive tests for antibodies to nuclear antigen, SS-A, and SS-B. Impaired cell-mediated immunity was also present. Bone marrow aspiration showed a hypoplastic marrow with an increased percentage of lymphocytes. A positive Schirmer's test and keratoconjunctivitis were also noted. A diagnosis of primary Sjögren's syndrome was made by sialography and histological salivary gland findings. Therapy with prednisolone improved the pancytopenia. Addition of the patient's peripheral blood mononuclear cells to cultures of bone marrow mononuclear cells derived from a healthy volunteer dose dependently inhibited colony formation, including mixed hemopoietic colonies. On the other hand, addition of the patient's serum failed to inhibit colony formation by normal bone marrow mononuclear cells. These results suggested that one of the causes of pancytopenia in primary Sjögren's syndrome might be mediated by the inhibition of mononuclear cells to the hemopoietic progenitors.

Systematic assessment of bone resorption, collagen synthesis, and calcification in chick embryonic calvaria in vitro: effects of prostaglandin E2

A systematic method has been developed to assess bone resorption, matrix formation, and calcification in a single calvarial culture from 20-day-old chick embryos. The bones were prelabeled with 45Ca by an injection into the egg white before culture. In the last 2 h of incubation, the bones were further labeled with both 3H-proline and 3H-tetracycline. Bone resorption was assessed as 45Ca release into the medium. Collagen synthesis was measured by the incorporation of 3H-proline into collagenase-digestible protein (CDP). Since tetracycline has been commonly used as an in vivo marker for osteoid calcification, we assessed in vitro calcification as the uptake of 3H-tetracycline into bone. By using this method, we studied the effects of prostaglandin E2 (PGE2) and indomethacin, which inhibits biosynthesis of PGE2, on bone resorption and formation. The cultured bone synthesized approximately 300 ng of PGE2 during every 24 h of incubation, and indomethacin (10(-6) M) completely inhibited the synthesis. In indomethacin-treated cultures, % 45Ca release and the labeling of CDP were significantly reduced. These reductions were not seen when exogenous PGE2 (10(-9) M) comparable to its endogenous level was added along with the indomethacin. Furthermore, 10(-8) to 10(-5) M PGE2 increased % 45Ca release and the CDP labeling. In addition, the uptake of 3H-tetracycline into the cultured bone was also enhanced by PGE2. In devitalized calvaria, PGE2 had no effect on 3H-tetracycline uptake, suggesting that the stimulative effect on PGE2 was cell-mediated.(ABSTRACT TRUNCATED AT 250 WORDS)

Dual roles of 90-kDa heat shock protein in the function of the mineralocorticoid receptor

Association of the 90-kDa heat shock protein (HSP90) is required for the high-affinity ligand-binding of the glucocorticoid receptor (GR), but not for that of the androgen receptor [Ohara-Nemoto, Y., Nemoto, T., & Ota, M. (1991) J. Biochem. 109, 113-119]. In the present study, we investigated the ligand- and HSP90-binding characteristics of the mineralocorticoid receptor (MR), which shares to some degree the ligand-binding specificity of the GR. A truncated human MR (designated MR351) starting from Gly-351 was translated in vitro with rabbit reticulocyte lysate. Scatchard analysis revealed the presence of a single class of high-affinity binding sites for [3H]aldosterone (Kd = 0.35 +/- 0.2 nM), comparable to those of the native receptor in target tissues. Glycerol gradient centrifugation and immunoadsorption analyses showed that MR351 associated with rabbit HSP90. Exposure to 0.4 M NaCl induced the dissociation of HSP90 from MR351 and simultaneously enhanced binding of MR351 to DNA-cellulose. Moreover, when measured at 10 nM, HSP90-free MR351 showed only 9% of the [3H]aldosterone-binding found in the presence of HSP90. On the other hand, when MR351 was expressed in Escherichia coli as a protein tagged with a histidine hexamer at the N-terminus (designated H6MR351), specific binding of [3H]aldosterone was detected. The binding affinity (Kd = 338 +/- 45 nM) was, however, 1,000-fold lower than that of MR351 translated in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

cAMP-dependent phosphorylation of nuclear proteins in mouse submandibular gland following testosterone administration

The effect of androgen on protein kinase activities was studied in chromosomal proteins from female mouse submandibular gland. The protein kinase activities in the nuclei were stimulated 3 h after testosterone administration. The in vitro addition of cAMP in the nuclei resulted in the enhancement of the androgen-sensitive protein kinase activities. SDS-PAGE analysis revealed that nonhistone proteins having molecular weights of 20-30 kDa and around 43 kDa were phosphorylated after androgen treatment. The addition of cAMP stimulated phosphorylation of nonhistone proteins having molecular weights with 15-25 kDa, 30 kDa and 35 kDa and the intensity of phosphorylation of these nonhistone proteins was enhanced after androgen treatment. These results suggest that androgen-sensitive protein kinases including cAMP-dependent protein kinase were present and that phosphorylation of nonhistone proteins by these protein kinases may be involved in mediating androgen-induced gene activation.

Evidence that nitric oxide can act centrally to stimulate vasopressin release

Nitric oxide (NO) is the endothelium-derived relaxing factor, which causes relaxation of vascular smooth muscle. NO synthetase, the enzyme for the synthesis of NO from its precursor L-arginine, is also widely distributed in neurons in the brain, and it has been suggested that NO may serve as an important neuromodulator. Because NO synthetase is present in the hypothalamus in relatively high concentration, we have determined whether NO can affect the release of vasopressin in conscious, chronically prepared rats. The intracerebroventricular (i.c.v.) injection of S-nitroso-N-acetylpenicillamine (12.5 and 25 micrograms; SNAP), that spontaneously breaks down to form NO, caused transient dose-related increases in the plasma vasopressin concentration of 1 and 2 microU/ml (p < 0.01), respectively. In control experiments in which N-acetylpenicillamine (25 micrograms), the precursor for the preparation of SNAP, was injected i.c.v. there was a small, 0.4 microU/ml, increase (p < 0.01) in the plasma vasopressin level. The i.c.v. injection of L-arginine (0.5 and 1 mg), also the precursor for the biosynthesis of NO, resulted in dose-dependent increases in the plasma vasopressin concentration similar in magnitude to those caused by SNAP. When D-arginine (1 mg), which cannot serve as a substrate for NO synthetase, was injected i.c.v., there was only a slight delayed increase in the plasma vasopressin concentration. Thus, NO can act centrally to stimulate vasopressin release and may serve as a neuromodulator in the control of vasopressin release.

Transfusion-associated graft-versus-host disease in an immunocompetent patient following accidental injury

We report a case of transfusion-associated graft-vs.-host disease (TA-GVHD) in a previously healthy, 58 year old Japanese man following an accidental injury. Despite intensive treatment, the patient died 22 days after the transfusion. Although many cases of fatal TA-GVHD have been reported in immunocompetent patients, only two are known to have developed this disorder unrelated to a surgical procedure. This is the first such case to be confirmed by HLA typing. Our report suggests that TA-GVHD can occur even in a healthy, immunocompetent recipient. Thus, it seems necessary to establish guidelines for the irradiation of cellular blood products before transfusion.