Isolation and characterization of cDNA clones corresponding to the genes expressed preferentially in floral organs of Arabidopsis thaliana

Seventeen cDNA clones of genes corresponding to mRNAs expressed preferentially in floral organs of Arabidopsis thaliana were obtained by differential screening of a flower bud cDNA library, and classified into five groups (1A, 17A, 1B, 4B and 5B) by cross-hybridization and restriction analysis. Sequence analysis revealed that the 1A-1 and 17A-1 clones encode vegetative storage proteins (VSPs). The VSP mRNAs were detected in a small amount in leaves and increased to a limited level by wounding. Both 1B-1 and 5B-1 clones were homologous to transmembrane protein cDNAs. The protein encoded by 4B-1 clone contained a proline-rich region, but no homologous proteins were found in databases.

Standard RUS skeletal maturation of Tokyo children

A total of 704 girls and 753 boys, all healthy, from 3 to 18 years of age, from Tokyo and its suburbs, were radiographed on the left hand and wrist in 1986. Their RUS (TW2) skeletal maturity was estimated, the 50th-centile skeletal maturity scores were obtained, and the smoothed RUS maturity curves were determined applying the cubic spline function to the 50th-centile scores. On this maturity curve the score at each 0.1 year of chronological age was obtained and allocated as a given RUS skeletal age. This set of scores and ages we termed the TW2-J RUS, i.e. the Japanese TW2 RUS maturity standard. Comparing this RUS standard with the British standard, the Belgian, the southern Chinese, and the northern Indian, it became clear that Japanese children's RUS skeletal maturity progresses rapidly during puberty (after ages 9 in girls and 11 in boys), and that the maximum score difference between neighbouring age groups was observed at ages 12.5 in girls and 14.5 in boys on the spline-smoothed curve. Japanese children attain the adult stage 1 or 2 years earlier than other groups of children (at ages 15 in girls and 16 in boys).

[Comparative study of bone marrow transplantation from unrelated donors and identical sibling donors in a single institute]

This retrospective study analyzes the result of bone marrow transplantation in 28 patients with unrelated donors compared with 75 patients transplanted from identical HLA sibling donors at a single institute during the same time period. One unrelated donor patient with severe aplastic anemia died without evidence of engraftment. The incidence of grade III-IV acute graft-versus-host disease (GVHD) in unrelated donor patients (19%) was higher than sibling donors (0%) and the probability of survival more than 30 years was lower compared with sibling donors. However, the probability of survival without grade III-IV acute GVHD was similar in the two groups, 62% (n = 21) vs. 65% (n = 75), and there was no significant difference in relapse-free survival, good prognostic factors; 76% (n = 11) vs. 66% (n = 37), higher risk factors; 30% (n = 11) vs. 31% (n = 21). Death due to viral infection were significantly higher among unrelated donor patients. We conclude that bone marrow transplantation for patients younger than 30 years old from unrelated donors should be considered equally to sibling donors with great care to engraftment for severe aplastic anemia, grade III-IV acute GVHD and viral infection.

Serum thrombopoietin level after allogeneic bone marrow transplantation: possible correlations with platelet recovery, acute graft-versus-host disease and hepatic veno-occlusive disease. Nagoya Bone Marrow Transplantation Group

Thrombopoietin (TPO) is a growth and differentiation factor for megakaryocytes and platelets. An ELISA was developed for measuring TPO concentrations in human sera. The mean +/- S.D. of TPO level obtained in 29 control subjects was 0.87 +/- 0.35 fmol/ml. We measured the TPO level in 36 patients after allogeneic bone marrow transplantation (BMT) and determined the relationship between blood levels of TPO and changes in the circulating platelet mass. In general, a reciprocal relationship was observed between TPO and platelet count (r = -0.609, P < 0.0001; n = 165). With the decrease in the platelet mass after myeloablative therapy, the TPO level increased proportionally and peaked during the platelet nadir. The peak concentration of TPO ranged from 20-50 fmol/ml. The TPO level decreased with the normalization of the platelet mass. In contrast, the TPO level decreased during acute graft-versus-host disease (GVHD) in several patients. Furthermore, the TPO level was significantly lower in the patients with hepatic veno-occlusive disease (VOD) than in the patients after BMT without GVHD and VOD in the samples of less than 50000/microliters platelets (P < 0.005). These findings suggest that in the patients given allogeneic BMT, TPO has an important role in the physiologic regulation of platelet production and that liver damage due to acute GVHD and VOD may decrease the TPO level.

Contact dermatitis due to rubber boots worn by Japanese farmers, with special attention to 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (ETMDQ) sensitivity

An investigation was conducted as follows in 9 farmers with contact allergy due to rubber boots: (i) patch tests with 19 rubber additives; (ii) chemical analysis of additives in 6 pairs of rubber boots; (iii) use tests on a hypoallergenic trial product in 5 patients. The following results were obtained: (i) in the patch tests, all 9 patients showed positive reactions to 1 or more of the nitrogen(N)-containing antioxidants (IPPD, DMBPPD, ETMDQ); (ii) ETMDQ was detected in 1 pair of rubber boots, and IPPD and DMBPPD in another pair; (iii) no patient using hypoallergenic boots during rice-planting had recurrent dermatitis. N-containing antioxidants, such as IPPD, DMBPPD and ETMDQ, were thus considered as the main causative agents and the trial product was found useful for managing contact dermatitis. Contact allergy due to ETMDQ in rubber is reported here for the 1st time.

[Intra-arterial infusion chemotherapy for breast cancer]

In order to reduce toxic effects while attaining maximal therapeutic effects, epirubicin 10 mg/day, cyclophosphamide 100 mg/day and prednisolone 10 mg/day were administered through in indwelling catheter inserted into the internal mammary artery and/or subclavian artery for 3-4 weeks, employing the implantable port system for the treatment of unresectable breast cancer and recurrent cancer. Ten out of 11 patients (91%) with unresectable breast cancer showed a response (CR 3, PR 7, NC 1) to this modality of intra-arterial infusion chemotherapy. Seven out of 11 patients (64%) with recurrent cancer of the breast showed a response (CR 1, PR 6, NC 4). Intraarterial infusion chemotherapy for the unresectable advanced breast cancer and recurrent breast cancer proved to be an effective modality of treatment.

[An autopsy case of late-onset chorea]

Senile chorea has been an ill-defined clinical entity because of the difficulty of differentiating it from Huntington's disease (HD) of late-onset type. The gene specific for HD has recently been found to contain an abnormal (CAG)n trinucleotide repeat which allows it to be differentiated from the other conditions. Our case of late-onset chorea was differentiated from HD by PCR. An 80-year-old man had experienced gradually increasing chorea of his tongue, arms and legs for 4 years, but had not exhibited character changes, mental symptoms or dementia. He died of pneumonia at 84 years. The pathological findings in this case were different from those of HD. The brain weighted 1220 g, and did not show striatal atrophy or neuronal loss. The most remarkable findings were numerous foamy spheroids scattered in the caudate and putamen and proliferation of fibrous astrocytes within the thin myelinated fiber bundles and in the neuropil. Similar findings were reported by Freidman et al. (1990). Although it is debatable whether this finding was responsible for the development of the chorea, this case should contribute to our understanding of senile chorea as a clinicopathological entity.

Altered mitochondrial gene expression in a maternal distorted leaf mutant of Arabidopsis induced by chloroplast mutator

Chloroplast mutator (chm) of Arabidopsis is a recessive nuclear mutation that causes green and white variegation in leaves and is inherited in a non-Mendelian fashion. In this study, we have identified and characterized a mutant observed in F1 and backcrossed BC1 populations from a cross between chm1-3 and ecotype Columbia. This mutant, maternal distorted leaf (MDL), grows very poorly and is distinguished by distorted rough leaves and aborted flowering organs. Electron microscopic observation showed that in MDL plants, a significant portion of mitochondria are abnormal and appear to be nonfunctional. DNA gel blot and sequence analysis of the MDL mitochondrial DNA (mtDNA) revealed rearrangements in two mtDNA fragments associated with rps3-rpl16 genes (encoding ribosomal proteins S3 and L16, respectively). One rearrangement resulted in the insertion of the rps3-rpl16 operon downstream of atp9. An independent deletion in this region had eliminated the majority of rps3. In contrast, another rearrangement deleted part of rpl16, whereas rps3 remained intact. RNA gel blot analysis indicated that expression of these genes is also altered as a consequence of the mtDNA rearrangements. Thus, a mutation at the CHM locus affects mitochondrial gene expression, and impaired mitochondrial function may result in the distorted phenotype.

Transcriptional activation of RACTK1 K+ channel gene by apical alkalization in renal cortical collecting duct cells

We have previously demonstrated that RACTK1 cDNA encodes a pH sensitive K+ channel expressed in the apical side of renal collecting tubule cells. To determine whether extracellular pH induces the RACTK1 gene expression in the renal cortical collecting duct (CCD) cells, we measured mRNA of the RACTK1 using cultured rabbit CCD cells. Alkalization of incubation medium activated the transcription of the RACKTK1 gene in a time- and dose-dependent manner after 1 h, and reached a maximal level after 12 h. To examine whether the stimulation of mRNA by alkalization of body fluid occurs also in vivo, mRNA levels were measured in mice loaded with acid or alkali. The RACTK1 mRNA was increased in association with the rise in urinary pH. To examine side face of the effect of pH on stimulation of mRNA, we observed the effect of pH in the apical or the basolateral side in the preparation where CCD cells were cultured on filter membrane supports. Alkalization of the apical side but not of the basolateral side, was shown to be a determinant in inducting the RACTK1 mRNA. These findings suggest that, in addition to rapid direct regulation of RACTK1 K+ channel conductance by intracellular pH, this channel is also regulated by the changes in luminal pH through synthesis of channel protein by transcriptional activation.

The high content of monoene fatty acids in the lipids of some midwater fishes: family Myctophidae

The total lipids of eleven species of Myctophids caught at depths between 20 and 700 m in the northern Pacific Ocean were analyzed using silicic acid column chromatography (lipid classes) and capillary gas chromatography (fatty acid and fatty alcohol composition). The major components in the lipid classes were triacylglycerols or wax esters; triacylglycerols were the dominant acyl neutral lipids (68.1-96.1%) in eight species, and wax esters were found as the dominant lipid (85.5-87.9%) in three species. The major fatty acids and alcohols contained in the wax esters of the three fishes were 18:1n-9, 20:1n-9, 20:1n-11, and 22:1n-11 for fatty acids, and 16:0, 18:1, 20:1 and 22:1 for fatty alcohols. Fatty acids in the triacylglycerols ranging from C14 to C22 were predominantly of even chain length. The major components were 16:0, 16:1n-7, 18:1n-9, 20:1n-11, 22:1n-11, 20:5n-3 (icosapentaenoic acid), and 22:6n-3 (docosahexaenoic acid). In both the triacylglycerols and the wax esters, the major fatty components were monoenoic acids and alcohols. It is suggested from the lipid chemistry of the Myctophids that they may prey on the same organisms as the certain pelagic fishes such as saury and herring, because the large quantities of monoenoic fatty acids are similar to those of saury, herring, and sprats whose lipids originate from their prey organisms such as zooplanktons which are rich in monoenoic wax esters.

[Clinical study of prulifloxacin on infectious enteritis. Japan Research Committee of Prulifloxacin, Research Group on Infectious Enteritis]

Prulifloxacin (PUFX), a new quinolone antimicrobial agent, was administered to a total of 122 patients and carriers to investigate its clinical efficacy, safety and usefulness in infectious enteritis (bacillary dysentery, enteritis caused by Salmonella spp. and enteropathogenic E. coli, cholera and so on). In addition, the minimum inhibitory concentration (MIC) of UFX (active compound) was determined against each clinical isolate, and compared with that of ciprofloxacin (CPFX), ofloxacin (OFLX), tosufloxacin (TFLX) and nalidixic acid (NA). The correlation between the concentration of UFX in feces and the change of the fecal microflora were also investigated when PUFX was administered to the patients with acute infectious enteritis. A daily dose of 400 mg of PUFX was administered orally in two divided doses (morning and evening) for 5 days, with the exception of 7 days administration against salmonella enteritis and 3 days administration against cholera. 84 cases were adapted for evaluating the usefulness. The clinical efficacy was 100% in all the enteritis except salmonella enteritis, in which it was 88.9% (8/9 cases). On the bacteriological efficacy, the elimination rate was 100% in all isolates except Salmonella spp., in which it was 75.0% (12/16 cases). As for the adverse effect, uriticaria in moderate degree was observed in 1 (0.9%) of 109 cases. Abnormal changes in laboratory findings were seen in 3 (3.0%) of 100 cases, consisting of 1 with eosinophilia and 2 with elevated S-GPT, although they were all slight in degree. The usefulness rate was 65.5% (55/84 cases) for "very useful" and 95.2% (80/84 cases) for "very useful" and "useful". MIC90 of UFX against Shigella spp., Salmonella spp., E. coli and V. cholerae, was 0.025, 0.05, 0.025 and 0.05 microgram/ml, respectively. These values were the same as those of CPFX and TFLX, and superior to OFLX and NA. UFX concentrations in feces followed by administration of PUFX in 3 cases with acute infectious enteritis were higher than that of MIC90 of UFX against Shigella spp., Salmonella spp., E. coli and V. cholerae. The changes of the fecal microflora, which influence the efficacy and safety of PUFX, were not observed.

[An evaluation of the incidence of hyperparathyroidism after 131I treatment for Basedow disease (Part I)]

It is known that external radiation can act as a developing factor in hyperparathyroidism (HPT). To clarify whether or not 131I acts as a factor of developing HPT or not, levels of calcium and parathyroid hormone in the blood were studied in 2,954 cases of patients treated with 131I (RI group) and 530 cases treated with antithyroid drugs (ATD group). The calcium level was measured in all cases treated with 131I and/or antithyroid drugs. PTH-M (parathyroid hormone) was measured in 262 cases of the RI group and 29 cases of the ATD group which showed levels over 10 mg/dl of calcium. Fifty-eight cases (2.50%) in the RI group and three cases (1.19%) in the ATD group showed over 560 pg/ml PTH-M, which is the highest normal value. The increase in incidence of cases with over 560 pg/ml PTH-M in the RI group versus that of the ATD group is statistically significant. However, there is no statistically significant difference in the annual incidence when the follow-up period is taken into account, because the follow-up period differed between the two groups. The incidence of cases with 560 pg/ml of PTH-M was higher in the older patients than in the younger patients. These results suggest that 131I treatment for Basedow disease affects increase in the development of HPT after treatment and that the age factor is also important in the above fact.

[An evaluation of the incidence of hyperparathyroidism after 131I treatment for Basedow disease (Part II)]

The authors reported in a previous paper that 131I treatment for Basedow disease tends to increase in development of hyperparathyroidism (HPT) after therapy, from results showing that the measurement of levels of parathyroid hormone and calcium in the blood showed higher levels in the 131I-treated (RI) group than in the anti-thyroid drugs (ATD) group after therapy for Basedow disease. In the present work, the incidence of HPT was studied in patients with HPT that developed after treatment with 131I and/or ATD for Basedow disease at Ito Hospital. Fifteen of nineteen HPT patients had been treated with 131I and the other four had been treated with ATD. Basedow patients of the same age and sex with HPT and treated in the same year at Ito Hospital were selected as the control population for this study. The populations were 223 cases treated with 131I and 199 cases with ATD. The incidence of HPT in the RI and ATD groups was 6.7 percent and 2.0 percent, respectively. The incidence in the RI group was apparently higher than that in the ATD group. The average latent periods in the RI group and in the ATD group were 13.5 years and 4.1 years respectively. In the RI group 11 cases underwent follow-up periods of more than 10 years and 4 cases were followed up for less than 10 years. For the ATD group 3 of 4 HPT cases were followed up for less than 3 years. In the population the average follow-up periods for the RI group and the ATD group were 5.9 years and 5.3 years respectively. A relationship between radiation dose and development of HPT was demonstrated in these 15 cases of HPT. These findings suggest that 131I treatments for Basedow disease may result in development of hyperparathyroidism but the length of the follow-up period may also be an important factor in the incidence.

Schistosoma mansoni infestation: an imported case of a Japanese patient

A 25-year-old male Japanese who had resided in Ethiopia, presented to our department with eosinophilia, which had been present for about 1 year. Stool examination revealed eggs of Schistosoma mansoni containing miracidia with flame cell activity, and he was diagnosed as having an infestation with this organism. He was treated with praziquantel, and a good parasitological therapeutic result was obtained. Although schistosomiasis mansoni is unfamiliar to Japanese doctors because the infecting organisms are not indigenous to Japan, doctors should be aware of this disease when they encounter patients with eosinophilia who have visited or resided in tropical developing countries.

Significance of the therapeutic range of serum theophylline concentration in the treatment of an attack of bronchial asthma

The purpose of this study was to evaluate the accuracy of the recommended theophylline therapeutic range in the treatment of acute airway obstruction. Twenty seven patients (20 to 64 years) with acute asthma attack were given aminophylline intravenously to obtain a theophylline concentration between 10 and 20 micrograms/ml. Peak expiratory flow rates (PEFR) and serum theophylline concentrations were measured before and after aminophylline injection. When a marked improvement was not seen after aminophylline injection, the treatment was followed by inhalation of a beta-agonist and intravenously administered hydrocortisone. In order to clarify the relationship between theophylline efficacy at a therapeutic level and PEFR, as measured before aminophylline administration, the patients were classified into four groups. Group A (n = 7): asthma attack persisted regardless of treatment with aminophylline, beta-agonist and hydrocortisone, group B (n = 7): asthma attack improved by aminophylline, beta-agonist and hydrocortisone, group C (n = 6): asthma attack improved by both aminophylline and beta-agonist, group D (n = 7): asthma attack improved by intravenous aminophylline alone. The means (+/- S.E.) PEFR before aminophylline administration were 94.3 +/- 11.31/min in group A, 114.3 +/- 10.01/min in group B, 196.7 +/- 22.21/min in group C, and 220.0 +/- 12.51/min in group D, respectively. There were significant differences in PEFR between the A and C, A and D, B and C, and B and D groups. These findings suggest that theophylline efficacy is not expected in patients with low PEFR (less than 2001/min) at the time of treatment of an attack, even if a therapeutic theophylline concentration was obtained.

Preparation and characterization of monoclonal antibodies specific for lauroylated isoform of bovine transducin alpha-subunit: immunohistochemical analysis of bovine retinas

The photoreceptor G protein transducin [alpha- and beta gamma-subunits (T alpha/T beta gamma)] plays a central role in the visual transduction process. The amino-terminus of bovine T alpha is modified by one of four distinct fatty acids-laurate (C12:0), myristate (C14:0), C14:1 (5-cis), and C14:2 (5-cis, 8-cis)-but the biological significance and the localization of the four isoforms of T alpha are poorly understood. To investigate the cellular distribution of each isoform, we prepared monoclonal antibodies against a synthetic C12:0-, C14:0-, C14:1-, or C14:2-nonapeptide corresponding to the N-terminal region of T alpha. Among several types of antibodies isolated, only one type, represented by LA4, reacted specifically with the C12:0-peptide as well as purified T alpha but not with the other proteins in bovine retinal homogenate, including recoverin, indicating that the epitope comprises both C12:0 and the N-terminal amino acids of T alpha. Immunohistochemical analyses of bovine retinal sections by LA4 showed the uniform distribution of C12:0-T alpha in almost all the rod outer segments. Hence, it seemed unlikely that each isoform of T alpha was localized in specific cells. This observation, together with evidence for a possible functional diversity among the isoforms, suggests that the four isoforms of T alpha in a single rod cell may contribute simultaneously to a fine tuning of the photon-signal transduction process.

Cyclic AMP augments cytokine-stimulated nitric oxide synthesis in rat cardiac myocytes

We investigated the effect of adenosine 3', 5'-cyclic monophosphate (cAMP) on inducible nitric oxide synthase (iNOS) expression in cultured neonatal rat cardiac myocytes. Incubation of cardiac myocytes for 24 h with interleukin-1 beta (IL-1 beta) caused a significant increase in the production of nitrite, a stable metabolite of nitric oxide. Dibutyl cAMP (db-cAMP) significantly augmented nitrite production by IL-1 beta-stimulated, but not by unstimulated cells, in a dose-dependent manner. db-cAMP also dose dependently increased nitrite production by tumor necrosis factor-alpha(TNF-alpha)-stimulated cells. Simultaneous incubation with NG-monomethyl-L-arginine completely inhibited the effect of db-cAMP on nitrite production. cAMP-induced nitrite production by cytokine-stimulated cells was accompanied by increased iNOS mRNA accumulation. The synergistic effect of cAMP on IL-1 beta-induced nitrite accumulation was mimicked by cAMP-generating agonists forskolin and isoproterenol. These results indicate that cAMP upregulates cytokine-induced iNOS expression in cardiac myocytes.

Establishment and characterization of transgenic mice expressing human platelet glycoprotein Ib alpha

The platelet glycoprotein (GP) Ib/IX/V is a hetero-oligomeric receptor complex for von Willebrand factor (vWF) and mediates platelet adhesion and aggregation under high shear stress conditions. It is composed of alpha and beta chain of GP Ib, GP IX, AND and GP V. To establish transgenic mice carrying human GP Ib alpha, we injected into mouse zygotes a 6 kb DNA fragment containing human GP Ib alpha gene that included entire coding sequence and putative promoter region. One hundred and thirteen offsprings were screened, and only one was found to express human GP Ib alpha protein and has passed the human GP Ib alpha gene as well as the expression of the gene to next generation. The expression of human GP Ib alpha in transgenic mice was limited to platelets and megakaryocytes. Glycocalicin, a proteolytic fragment of human GP Ib alpha found in normal human plasma, was not detected in transgenic mouse plasma. Human vWF in the presence of ristocetin supported agglutination of transgenic mouse platelets, but not of control mouse platelets.

Hemodynamic forces modulate the effects of cytokines on fibrinolytic activity of endothelial cells

We investigated the effects of hemodynamic force on fibrinolytic activity of cultured human umbilical vein endothelial cells stimulated by cytokines, using a modified cone-plate viscometer in which well-controlled and -defined shear forces were generated. Treatment of the cells with interleukin (IL)-beta or tumor necrosis factor alpha (TNFalpha) under static conditions had no effect on tissue plasminogen activator (t-PA) secretion, while release of plasminogen activator inhibitor 1 (PAI-1) increased. When cells were exposed to increasing shear stress up to 24 dynes/cm2, levels of t-PA and t-PA/PAI-1 complex significantly increased relative to shear stress, while total PAI-1 and active PAI-1 secretion decreased gradually. In the presence of IL-1beta or TNFalpha, the increase in production of t-PA and the t-PA/PAI-1 complex was further augmented. Dot blot hybridization analysis of cultured cells in similar experimental conditions using t-PA and PAI-1 cDNA probes revealed no t-PA mRNA in 3 microg total RNA from static endothelial cells under resting or cytokine-stimulated conditions, but abundant t-PA mRNA was detected in cells subjected to a shear force of 18 dynes/cm2, and the increase was further augmented by addition of cytokines. In contrast, PAI-1 mRNA was detected in resting and cytokine-stimulated, nonsheared endothelial cells, but levels decreased after exposure to shear stress, even in the presence of cytokines. These results indicate a role for hemodynamic forces in regulating fibrinolytic activity with or without cytokine stimulation.

Stimulation of the activities of hepatic fatty acid oxidation enzymes by dietary fat rich in alpha-linolenic acid in rats

The activities of hepatic fatty acid oxidation enzymes in rats fed perilla oil rich in alpha-linolenic acid (alpha-18:3) were compared with those fed saturated fats or safflower oil (the mixture of safflower oil and olive oil, 94:8, w/w) containing the same amount of polyunsaturated fatty acids with perilla oil exclusively as linoleic acid (18:2). When the rats were fed the diets containing 15% coconut, safflower, and perilla oils for 1 week, the rate of mitochondrial and peroxisomal oxidation of palmitoyl-CoA (16:0-CoA) in the liver homogenates was the highest in rats fed perilla oil. Among the rats fed the diets containing 15% palm, safflower, and perilla oils for 2 weeks, the rates of mitochondrial and peroxisomal oxidations of 16:0-, 18:2-, and alpha-18:3-CoAs were the highest in rats fed perilla oil, and the rate of oxidation of alpha-18:3-CoA by both pathways was higher than those of other acyl-CoAs in all groups. Dietary perilla oil relative to palm and safflower oils significantly increased the activities of carnitine palmitoyltransferase, acyl-CoA dehydrogenase, acyl-CoA oxidase, and 2,4-dienoyl-CoA reductase. The substrate specificity of carnitine palmitoyltransferase appeared to be responsible for differential rates of the mitochondrial oxidation of acyl-CoAs. The substrate specificity of acyl-CoA oxidase did not account for the preferential peroxisomal oxidation of alpha-18:3 relative to 18:2. The preferential mitochondrial and peroxisomal beta-oxidation of alpha-18:3-CoA relative to 16:0- and 18:2-CoAs was also confirmed in rats fed laboratory chow irrespective of the substrate/albumin ratios in the assay mixture. It was suggested that both substrate specificities and alterations in the activities of the enzymes in beta-oxidation pathway play a significant role in the regulation of the serum lipid concentrations in rats fed a diet rich in alpha-18:3.

Electrophysiological characterization of RACTK1 K+ channel in stable cell line

RACTK1 is a pH-sensitive K+ channel cloned from rabbit renal collecting tubule cells. To characterize the function of this K+ channel in more detail, RACTK1 was transfected to an established cell line and the patch-clamp study was performed. cDNA of RACTK1 was inserted in the pMAM vector and transfected to Chinese hamster ovary cells. In one of 36 cell lines, the channel protein as expressed by the dexamethasone-induced mRNA and was detected by the specific antibody. The RACTK1 K+ channel with 80 pS was consistently observed. In inside-out patch, Ca2+ at concentrations higher than 500 nM activated the channel. Open probability was decreased by protein kinase A (from 45 to 4.2%, n+6) but not by protein kinase C. Whole cell currents of the transformed cells represented K+ conductance that was not blocked by an addition of charybdotoxin but by apamin. RACTK1 K+ channel has similar, though not identical, characteristics to the Ca2+ -activated K+ channel. RACTK1 might therefore encode a subunit of the intermediate conductance Ca2+ -activated K+ channel observed in the apical membrane of the rabbit renal collecting duct.