Immediate inhibition by oral l-ephedrine of passive cutaneous anaphylaxis of rats: indirect inhibition of anaphylactic chemical mediator release from the mast cell

OBJECTIVE AND DESIGN

We previously reported that oral l-ephedrine showed extraordinarily rapid inhibition of 48-h passive cutaneous anaphylaxis (PCA) in rats. In the present study, in vivo and in vitro experiments were performed to elucidate a possible mechanism for the inhibition.

MATERIALS

Rat antiserum was prepared with dinitrophenylated Ascaris suum extract + Bordetella pertussis.

TREATMENT

Wistar rats were passively skin-sensitised, actively sensitised or non-sensitised. l-Ephedrine immediately before provocations was orally or intravenously administered in in vivo experiments. In in vitro experiments, the drug was added at various time and concentrations before the challenge.

METHODS

The intensity of PCA was assessed by dye leakage method. Histamine and serotonin released in vitro or retained in the skin in vivo by anaphylaxis were assayed fluorometrically.

RESULTS

Oral l-ephedrine rapidly inhibited the PCA by inhibiting the release of histamine and serotonin from the reaction site, whereas anaphylactic histamine and serotonin releases from skin fragments were not affected by the drug. Furthermore, the orally administered drug influenced neither the histamine- nor serotonin-induced cutaneous vascular permeability.

CONCLUSIONS

These results were strongly indicative that the prompt suppression of the PCA by oral l-ephedrine was not exerted following the drug was absorbed from the gastrointestinal tract. Thus, the result may be from an indirect inhibition of chemical mediator release, possibly through an unidentified stimulation of the nervous system, but not from the inhibition of chemical mediator release by the direct interaction of drug to mast cells and not from the decreased vascular permeability.

Hypercalcemia in a patient with renal cell carcinoma producing parathyroid hormone-related protein and interleukin-6

A patient with renal cell carcinoma who developed humoral hypercalcemia of malignancy is reported. A 52-year-old male patient was diagnosed with renal cell carcinoma and multiple lung metastases. A cell line isolated from the surgical specimen exhibited continuous production of parathyroid hormone-related protein (PTHrP) in vitro. The production of PTHrP from the cancer cells was confirmed by RT-PCR and immunoradiometric assay. The serum calcium level was not enhanced, whereas the lung lesion was developing and producing interleukin-6, a possible modulator of osteoclastic resorption. Hypercalcemia was induced when the PTHrP concentration increased up to 3.3 pmol/L.

Simultaneous production of granulocyte colony-stimulating factor and parathyroid hormone-related protein in bladder cancer

A case of bladder cancer with simultaneous production of granulocyte colony-stimulating factor (G-CSF) and parathyroid hormone-related protein (PTHrP) is reported. An 81-year-old male patient was admitted to the Saitama Medical School for treatment of gross hematuria, leukocytosis and hypercalcemia and diagnosed as having advanced bladder cancer. Immediately after a cystectomy was carried out, his white cell count and serum calcium levels returned to normal. However, the tumors recurred locally and the recurrence was accompanied by an increase in the serum G-CSF and PTHrP levels with a recurrent elevation of white cell count and the serum calcium level. The production of G-CSF and PTHrP in the tumor cells was confirmed by immunohistochemistry.

Patch clamp studies on V-type ATPase of vacuolar membrane of haploid Saccharomyces cerevisiae. Preparation and utilization of a giant cell containing a giant vacuole

A method for obtaining giant protoplasts of Escherichia coli (the spheroplast incubation (SI) method: Kuroda et al. (Kuroda, T., Okuda, N., Saitoh, N., Hiyama, T., Terasaki, Y., Anazawa, H., Hirata, A., Mogi, T., Kusaka, I., Tsuchiya, T., and Yabe, I. (1998) J. Biol. Chem. 273, 16897-16904) was adapted to haploid cells of Saccharomyces cerevisiae. The yeast cell grew to become as large as 20 micrometer in diameter and to contain an oversized vacuole inside. A patch clamp technique in the whole cell/vacuole recording mode was applied for the vacuole isolated by osmotic shock. At zero membrane potential, ATP induced a strong current (as high as 100 pA; specific activity, 0.1 pA/micrometer(2)) toward the inside of the vacuole. Bafilomycin A(1,) a specific inhibitor of the V-type ATPase, strongly inhibited the activity (K(i) = 10 nM). Complete inhibition at higher concentrations indicated that any other ATP-driven transport systems were not expressed under the present incubation conditions. This current was not observed in the vacuoles prepared from a mutant that disrupted a catalytic subunit of the V-type ATPase (RH105(Deltavma1::TRP)). The K(m) value for the ATP dose response of the current was 159 microM and the H(+)/ATP ratio estimated from the reversible potential of the V-I curve was 3.5 +/- 0.3. These values agreed well with those previously estimated by measuring the V-type ATPase activity biochemically. This method can potentially be applied to any type of ion channel, ion pump, and ion transporter in S. cerevisiae, and can also be used to investigate gene functions in various organisms by using yeast cells as hosts for homologous and heterogeneous expression systems.

Suppression of default apoptosis in androgen-dependent cells by testosterone-mediated bcl-2 expression

BACKGROUND

The significance of apoptosis with regard to the development and progression of androgen-dependent cells has not been clearly understood. In the present study we investigated the expression of the bcl-2 proto-oncogene after androgen deprivation and its role in cell growth in an androgen-dependent cell line.

METHODS

We used SC2G, an androgen-dependent mouse mammary carcinoma cell line cloned from Shionogi carcinoma 115 (SC115). The expression of bcl-2 mRNA and protein in SC2G cells was measured by reverse transcription-polymerase chain reaction and western blotting, respectively. We also investigated the effects of antisense oligodeoxynucleotides (ODN) complementary to strategic sites in the mouse bcl-2 gene in SC2G cells.

RESULTS

When SC2G cells were cultured in serum-free medium, the number of viable cells was significantly larger among cells with testosterone than those without testosterone after 3 days. Apoptosis was demonstrated in approximately 30% of positive-staining nuclei in SC2G cells cultured in testosterone-free medium. The levels of bcl-2 mRNA and protein in SC2G cells started to decrease after testosterone withdrawal. The cell density of SC2G cells decreased after 4 days culture with antisense ODN when compared with cells cultured in the presence of sense control.

CONCLUSIONS

These data indicate that bcl-2 proto-oncogene inhibits the self-programmed apoptosis of androgen-dependent cells, suggesting the possibility of an antisense therapy for hormone-refractory prostate cancer, which is reported to express high levels of Bcl-2 protein.

TAP polymorphism is not associated with ankylosing spondylitis and complications with acute anterior uveitis in HLA-B27-positive Japanese

HLA-B27 is associated with the etiology of ankylosing spondylitis (AS) and acute anterior uveitis (AAU). Transporter associated with antigen processing (TAP) 1 and TAP2 polymorphism influences the range of peptide presented by HLA class I molecules. In this report, contribution of TAP polymorphism to the susceptibility to AS and AAU was studied in HLA-B27-positive Japanese individuals. Patients were classified into three groups: 16 AS patients, 14 AAU patients and 22 patients with both AS and AAU. Twelve HLA-B27-positive healthy individuals were included as a control. TAP polymorphism was detected by PCR-RFLP methods. Significant differences in frequencies of TAP1 alleles were not found between patient groups. None of the TAP2 frequencies showed increased or decreased frequencies compared with HLA-B27-positive healthy controls. In comparison with a random Japanese control, TAP2D allele frequency was significantly increased in the AAU group, but failed to reach a significant level in a group consisting of the AAU-only patients and the patients with both AS and AAU. All of the patient groups were noted to have a significantly increased prevalence of the TAP2H allele as compared to random controls; however, the higher frequency of this allele was detected in HLA-B27 healthy controls as well. These observations suggest a linkage disequilibrium between TAP2D, TAP2H and HLA-B27 in Japanese.

[Anti-proliferative effects of heating on the human prostatic carcinoma cells in culture]

Prostatic cancers are well-known to be sensitive to heat stress. However, the mechanism by which the cancer cells are killed by high temperature remains poorly understood. The present study was undertaken to determine the anti-proliferative effects of heat stress on the prostatic cancer cells in culture. Heat shock at 43 degrees C inhibited the cell growth of three different prostatic cell lines. Flow cytometrical analysis using BrdU and PI showed a decrease in the proportion of cells in an S phase, accompanied by cell accumulation in G1 and G2, in both JCA-1 and PC-3 but not in LNcap. Both JCA-1 and PC-3 presented a strong expression of hsp70 at 37 degrees C. The heat shock caused apparent enhancement of the expression of hsp70 through the cell cycle. A treatment at 43 degrees C for 8 hours resulted in not only an apparent increment of positive hsp70 cells, but cells with subdiploid DNA content in LNcap. Flow cytometrical analysis by FITC-labeled Annexin V showed increment of apoptotic cells at 43 degrees C for 8 hours in LNcap cells. The results suggest that apoptosis is an important pathway of heat-induced killing of these cells. In conclusion, the cell growth of prostatic cancers may be affected by the temperature through relationship of the cell cycle and hsp70.

Sensitive high-performance liquid chromatographic method with fluorometric detection for the determination of heparin and heparan sulfate in biological samples: application to human urinary heparan sulfate

A sensitive high-performance liquid chromatographic method for the determination of unsaturated disaccharides produced from heparin and heparan sulfate is described. Heparan sulfate was depolymerized using a combination of heparin lyase I (EC 4.2.2.7), heparin lyase II and heparin lyase III (EC 4.2.2.8). Seven unsaturated disaccharides were separated under isocratic conditions within 25 min using acetonitrile-H2O-0.2 M sodium phosphate buffer (pH 7.0)-3.0 M ammonium chloride (32:10:1:1) and were monitored by fluorescence detection using 2-cyanoacetamide as a post-column derivatizing reagent. As little as 2 pmol of a disaccharide could be detected with excitation at 346 nm and emission at 410 nm. This method was applied to the analysis of normal human urine. It was revealed that the concentration of normal human urinary heparan sulfate is 1.53+/-0.36 mg/mg creatinine (n=4).

A novel interferon-inducible gene expressed during myeloid differentiation

The acute promyelocytic leukemia cell line, NB4, can be induced to differentiate to mature granulocytes by retinoic acid treatment. A novel retinoic acid-inducible cDNA clone, designated RI58, was isolated from a cDNA library constructed from retinoic acid-treated NB4 cells by differential hybridization. RI58 cDNA encodes a protein of 58kDa which has a similarity in its amino acids sequence to interferon (IFN)-inducible proteins. In addition, RI58 was induced by recombinant human IFN-alpha (rhIFN-alpha) in NB4 cells. RI58 was detectable within 4 hours post-stimulation with rhIFN-alpha, while it took as long as 1day after retinoic acid stimulation. Culture supernatant from retinoic acid-treated NB4 cells also induced RI58 expression similarly as rhIFN-alpha. This activity in culture supernatant was inhibited by anti-leukocyte IFN antiserum which showed specific reactivity to rhIFN-alpha. These results indicate that RI58 is induced by retinoic acid stimulation through autocrinally secreted IFN-alpha from NB4 cells. In the retinoic acid-treated NB4 cells, the expression of RI58 was increased along the process of differentiation. On the other hand, it was expressed constitutively in untreated non-hematopoietic cell lines and mature hematopoietic cell lines.

[Activation of skin cells by inorganic compounds]

It has been known that the stimulation of skin cells by physiologically active substances is accompanied by the quantitative and qualitative alterations of the glycosaminoglycans (GAGs) in skin. This phenomenon make it possible to evaluate the activity of test substances for the stimulation of skin cells. The purpose of our study is to elucidate the effectiveness of inorganic compounds for the stimulation of skin cells. (1) The cultured skin cells including keratinocytes and fibroblasts, (2) the cultured model skin constituted of collagen gel, fibroblasts and keratinocytes, and (3) the mouse damaged skin were used in the present study. The results obtained from these studies demonstrate that inorganic substances commonly have a possibility to activate cyclic AMP-dependent protein kinase (A-kinase), and the A-kinase activation results in an increase in GAGs. These findings brought the scientific basis for the effectiveness of the Japanese traditional balneotherapy for damaged skin.

[Retinoic acid-induced cell growth inhibition and differentiation in testicular carcinoma cells in culture]

Testicular germ tumor cells could be differentiated spontaneously or by some chemotherapeutic compounds. However, the mechanism by which the cells are differentiating from the stem cell remains unclear. The KU-MT cells, which were newly established from lung metastasis of testicular carcinoma, have been continuously producing alpha fetoprotein (AFP). Retinoic acids are well-known to induce cellular differentiation in culture and have already been applied for a clinical usage against leukemia. In the present study, all-trans-retionic acid (ATRA) elevated the level of AFP and inhibited the growth of KU-MT cells in vitro. ATRA also arrested the cell cycle in G1 and reduced the percentage of the S phase cell in terms of wild type p53, leading to apoptosis in part. Retinoids, especially retinoic acid receptor (RAR)-alpha specific agonists induced laminin production, a marker of endodermal differentiation; whereas arotinoid, a retinoid not bound to RAR-alpha, did not affect laminin expression. In summary, retinoic acids could mediate cell growth and differentiation of testicular tumor through RAR-alpha.

VMA11 and VMA16 encode second and third proteolipid subunits of the Saccharomyces cerevisiae vacuolar membrane H+-ATPase

The vacuolar membrane H+-ATPase (V-ATPase) of the yeast Saccharomyces cerevisiae is composed of peripheral catalytic (V1) and integral membrane (V0) domains. The 17-kDa proteolipid subunit (VMA3 gene product; Vma3p) is predicted to constitute at least part of the proton translocating pore of V0. Recently, two VMA3 homologues, VMA11 and VMA16 (PPA1), have been identified in yeast, and VMA11 has been shown to be required for the V-ATPase activity. Cells disrupted for the VMA16 gene displayed the same phenotypes as those lacking either Vma3p or Vma11p; the mutant cells lost V-ATPase activity and failed to assemble V-ATPase subunits onto the vacuolar membrane. Epitope-tagged Vma11p and Vma16p were detected on the vacuolar membrane by immunofluorescence microscopy. Density gradient fractionation of the solubilized vacuolar proteins demonstrated that the tagged proteins copurified with the V-ATPase complex. We conclude that Vma11p and Vma16p are essential subunits of the V-ATPase. Vma3p contains a conserved glutamic acid residue (Glu137) whose carboxyl side chain is predicted to be important for proton transport activity. Mutational analysis of Vma11p and Vma16p revealed that both proteins contain a glutamic acid residue (Vma11p Glu145 and Vma16p Glu108) functionally similar to Vma3p Glu137. These residues could only be functionally substituted by an aspartic acid residue, because other mutations we examined inactivated the enzyme activity. Assembly and vacuolar targeting of the enzyme complex was not inhibited by these mutations. These results suggest that the three proteolipid subunits have similar but not redundant functions, each of which is most likely involved in proton transport activity of the enzyme complex. Yeast cells contain V0 and V1 subcomplexes in the vacuolar membrane and in the cytosol, respectively, that can be assembled into the active V0V1 complex in vivo. Surprisingly, loss-of-function mutations of either Vma11p Glu145 or Vma16p Glu108 resulted in a higher degree of assembly of the V1 subunits onto the V0 subcomplex in the vacuolar membrane.

Reducing activity level of alliin

Alliin has been reported to have antioxidative activity. We tried to reexamine the antioxidative activity of alliin with a purified alliin preparation, and found that it has no antioxidative activity in a linoleic acid oxidation system. The reducing activity of alliin tested by the ECD method was also weak in showing antioxidative activity.

[HLA and uveitis in leprosy]

In order to investigate the role of immunogenetic factors in the pathogenesis of uveitis in leprosy, human leukocyte antigens (HLA) were analyzed among leprotics with and without uveitis. The subjects were 85 Japanese leprosy patients, 44 with uveitis and 41 without uveitis. Controls were 138 healthy subjects. A modified two-stage complement dependent microcytotoxicity test was used for typing HLA-A, -B, -C, -DR and -DQ antigens. The occurrence of HLA-DR2 antigen was significantly increased in patients as a whole (69.4%), and in the patients with uveitis (79.5%) as compared with the control subjects (35.5%). The association with DR2 was even stronger in the patients with uveitis (odds ratio = 7.1, Pc < 0.000005) than in the patients as a whole (odds ratio = 4.1, Pc < 0.0001). On the other hand, HLA-DR53 antigen was significantly decreased in the patients as a whole (43.5%) and in the patients with uveitis (36.4%) as compared with the control subjects (69.6%). No significant difference in the distribution of HLA antigens was observed in the patients without uveitis. Our results suggest that HLA-DR2 contributes to the susceptibility to uveitis in Japanese leprosy patients.

Isolation of Porphyromonas gingivalis strain from tubal-ovarian abscess

An unusual case of involvement of Porphyromonas gingivalis is described. Two anaerobic isolates, identified as Fusobacterium nucleatum and P. gingivalis, were recovered from the pus of a tubal-ovarian abscess in a 35-year-old woman. Identification of the P. gingivalis isolate was confirmed by randomly amplified polymorphic DNA fingerprinting.

Patients with hepatitis A with negative IgM-HA antibody at early stages

Two patients with acute liver dysfunction who were negative for serum IgM-HA antibody on presentation became positive a week later. At early stages of hepatitis A, serum IgM-HA antibody may be negative. Another assay approximately 2 wk apart is recommended.

[HLA-DR2 alleles and uveitis in leprosy]

In order to investigate the role of immunogenetic factors in the pathogenesis of uveitis in leprosy, HLA antigens were analyzed between the leprotics with and without uveitis. Sixty-five Japanese leprosy patients comprised 32 with uveitis and 33 without uveitis. Controls consisted of 138 healthy subjects. A lymphocyte cytotoxicity test was used for typing HLA-A, -B, -C, -DR and -DQ antigens. HLA-DR2 genotyping was performed by the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and PCR-restriction fragment length polymorphism (RFLP) methods. The frequency of HLA-DR2 antigen was significantly increased in the patients with uveitis as compared with the control subjects (Pc < 0.0005), whereas HLA-DR53 antigen was significantly decreased (Pc < 0.05). At the genomic level the frequency of HLA-DRB1*1501 was significantly increased in the patients with uveitis and without uveitis as compared with that in the controls. The association with DRB1*1501 was even stronger in patients with uveitis (odds ratio = 7.1, Pc < 0.000005) than in the patients without uveitis (odds ratio = 4.1, Pc < 0.005). Our results suggest that HLA-DRB1*1501 contribute to the susceptibility to uveitis in the Japanese with leprosy.

Administration of phosphatidylcholine increases brain acetylcholine concentration and improves memory in mice with dementia

Studies on the effect of phosphatidylcholine administration on memory are limited. We administered egg phosphatidylcholine to mice with dementia and to normal mice and compared the differences in memory and serum choline concentration, and choline and acetylcholine concentrations and choline acetyltransferase activities of three forebrain regions (cortex, hippocampus and the remaining forebrain). Mice with dementia were produced by mating sibling mice who had impaired memory for > 20 generations. These mice had poor memory and low brain acetylcholine concentration. We administered 100 mg of egg phosphatidylcholine (phosphatidylcholine group) or water (control group) by gavage to each mouse daily for about 45 d. Control mice with dementia had poorer memory in passive avoidance performance and lower brain choline (cortex and hippocampus) and acetylcholine (hippocampus and forebrain excluding cortex and hippocampus) concentrations and lower cortex choline acetyltransferase activity than the control normal mice (P < 0.05). The administration of phosphatidylcholine to mice with dementia improved memory and generally increased brain choline and acetylcholine concentrations to or above the levels of the control normal mice. In normal mice, phosphatidylcholine treatment did not affect memory or acetylcholine concentrations in spite of the great increase in choline concentrations in the three brain regions. Serum choline concentration in mice treated with phosphatidylcholine increased to a similar level in both strains of mice, indicating that the absorption of phosphatidylcholine was not impaired in mice with dementia. The results suggest that administration of egg phosphatidylcholine to mice with dementia increases brain acetylcholine concentration and improves memory.

HLA-DR8 and acute anterior uveitis in ankylosing spondylitis

OBJECTIVE

To identify possible factors in the development of acute anterior uveitis (AUU) in patients with ankylosing spondylitis (AS).

METHODS

We investigated HLA antigens serologically, and HLA-DRB1*08 alleles by polymerase chain reaction-restriction fragment length polymorphism, in 42 Japanese AS patients with and without AAU.

RESULTS

Thirty-six of the AS patients (85.7%) had HLA-B27. Thirteen (65%) of the 20 patients with AAU had HLA-DR8, whereas only 1 (4.5%) of the 22 patients without AAU had DR8. The difference was statistically significant (Pcorr < 0.001).

CONCLUSION

Our data suggest that HLA-B27 is strongly associated with AS in Japanese patients and that HLA-DR8 is important for the development of AAU in Japanese patients with AS.

HLA class II genes in Vogt-Koyanagi-Harada disease

PURPOSE

Vogt-Koyanagi-Harada disease (VKH) is an autoimmune disorder causing a bilateral diffuse granulomatous uveitis, often with several associated extraocular manifestations. Strong association of human leukocyte antigens (HLA) antigens with the disease has been documented. The details of all HLA class II genotypes were investigated in Japanese patients with VKH to demonstrate the immunogenetic background of the disease.

METHODS

Human leukocyte antigen tissue typing was performed in 57 Japanese patients with VKH by the modified two-stage complement-dependent microcytotoxicity method. DNA analyses were done by polymerase chain reaction (PCR)-single-strand conformation polymorphism and PCR-restriction fragment-length polymorphism methods.

RESULTS

The frequencies of HLA-DR4 and HLA-DQ4 were 93% and 83% among the patients with VKH, compared with 43% and 32% among the controls, respectively (relative risks, 17.4 and 9.9; Pc < 1.0 x 10(-10)). At the genomic level, all patients had the HLA-DQA1*0301 genotype, which was present in only 67% of the normal controls (relative risk, 56.5; Pc < 1.0 x 10(-5)). With allelic combinations, -DQA1*0301/-DR4 showed the greatest relative risk ratio. Conversely, DQB1*0604 genotype was not detected among the patients.

CONCLUSION

It can be postulated that VKH is a disease of combined allelic predisposition in which DQA1*0301 acts as the primary and HLA-DR4 acts as an additive factor in the development of the disease. Based on the negative association of DQB1*0604, we propose that DQB1*0604 provides considerable protection, possibly by altering other factors in the pathogenesis of VKH in the Japanese.

Protozyme: emerging evidence in nature

The VMA1 locus in Saccharomyces cerevisiae contains a nested genetic element, the VDE gene, and expresses two functional proteins. A single VMA1 translational product seems to catalyze a self protein splicing in which an internal domain is excised out to produce a site-specific DNA endonuclease and the N- and C-domains are ligated by a transpeptidation reaction to yield a catalytic subunit of the vacuolar ATPase. Accumulating evidence in the past few years suggests that the VMA1 locus encodes a protozyme (for protos en zyme) which has dual roles in life as a protean catalyst for self protein splicing and for self gene homing. Four protozymes that share a common mechanism in protein splicing have been found in four organisms covering three major phylogenic trees.

A prospective study on hepatocellular carcinoma in liver cirrhosis: respective roles of alcohol and hepatitis C virus infection

To assess the interaction of alcohol and HCV infection in hepatocarcinogenesis, we prospectively studied 447 patients with liver cirrhosis (LC) who presented to our out-patient clinics in a month; 163 patients with habitual drinking (AL-LC) who had taken more than 72 g alcohol per day (HCV positive 79 cases: HCV+AL; HCV negative 84 cases: AL); 176 with HCV infection but without alcohol intake; 39 with HB infection; and 82 with liver disease from other etiologies such as primary biliary cirrhosis (PBC). In the HCV group, HCC developed in 15 patients in the first year and 10 in the second year; the cumulative appearance rate was 11% and 16%, respectively. There was no difference in the HCC appearance rate between the two groups. In the AL group, the cumulative HCC occurrence rate was only 2% in the first year, and 2% in the second year. The appearance rate was significantly lower in the AL group compared with the HCV and the HCV+AL groups. One-hundred and fourteen patients (94 with HCV, 20 with HCV+AL) who had a history of blood transfusion more than 10 years ago were selected. A year-adjusted disease occurrence rate calculated by the Kaplan-Meier method showed that the HCV+AL group had a significantly higher disease occurrence rate than the HCV group. Theses results suggest that although alcohol alone does not become an independent risk factor for HCC from LC, it may accelerate the development of HCC caused by HCV, at least in the group with a history of blood transfusion.

Unique associations between HLA-B and HLA-DRB1*04 gene variants in Japanese

HLA-DRB1*04 gene variants were determined in apparently healthy Japanese with PCR-SSCP and PCR-RFLP, and HLA-B-DRB1*04 haplotype frequencies were estimated statistically. DRB1*0405, which consisted of 60% of the Japanese DRB1*04 gene pool, was associated strongly with HLA-B54. This association was observed only for DRB1*0405, and not for any other DR4 variants. DRB1*0403 and DRB1*0406, which share the same peptide sequence except for amino acid 37, were both associated with B35 and B62. DRB1*0407 was associated exclusively with B35. DRB1*0410 was associated with B60 and B61. B60 and B61, on the other hand, were associated only with DRB1*0410 and DRB1*0405. B35 was associated with all DR4 microvariants. With this possible exception, our calculation suggests that unique B-DR associations were present even for DR4 microvariants. The knowledge of HLA-B and DRB1*04 associations would be useful in clinical settings.

VMA13 encodes a 54-kDa vacuolar H(+)-ATPase subunit required for activity but not assembly of the enzyme complex in Saccharomyces cerevisiae

Previous purifications and characterizations of the Saccharomyces cerevisiae vacuolar proton-translocating ATPase (V-ATPase) have indicated that this enzyme is a multisubunit complex composed of at least eight subunits of 100-, 69-, 60-, 42-, 36-, 32-, 27-, and 17-kDa (Kane, P. M., Yamashiro, C. T., and Stevens, T. H. (1989) J. Biol. Chem. 264, 19236-19244). We report the cloning and characterization of an additional V-ATPase subunit, the 54-kDa subunit, which is encoded by the VMA13 gene. VMA13 was isolated by complementation of the growth phenotypes associated with the vma13 mutation, which was originally described as cls11 (Ohya, Y., Umemoto, N., Tanida, I., Ohta, A., Iida, H., and Anraku, Y. (1991) J. Biol. Chem. 266, 13971-13977). The nucleotide sequence of the VMA13 gene predicted a hydrophilic polypeptide with a calculated molecular mass of 54,415 daltons. The VMA13 54-kDa gene product resides on the vacuolar membrane and co-purified with the active V-ATPase complex. Characterization of a null vma13 mutant (delta vma13) revealed that the Vma13 polypeptide is essential for V-ATPase activity. However, the Vma13 polypeptide is not required for targeting of the other V-ATPase subunits (100-, 69-, 60-, 42-, 27-, or 17-kDa subunits) to the vacuolar membrane as shown by the association of these subunits with vacuolar membranes isolated from delta vma13 cells. The nature of the V-ATPase "complex" in delta vma13 mutant is, nevertheless, fundamentally different from the wild-type enzyme. This is evidenced by the fact that the inactive V-ATPase complex from delta vma13 cells is less stable than the wild-type enzyme. Taken together, these results indicate that VMA13 encodes the 54-kDa subunit of the V-ATPase and that this subunit is essential for activity, but not assembly, of the enzyme complex.