Analysis of the murine All-1 gene reveals conserved domains with human ALL-1 and identifies a motif shared with DNA methyltransferases

A series of translocation break points found in a subset of human acute leukemias have one of the breaks on human chromosome 11q23. This region has recently been cloned and a large gene, ALL-1, with homology to the Drosophila trithorax gene has been identified. This paper describes the cloning, sequencing, and mapping of the mouse homolog of ALL-1. We have found a motif present in All-1 that shows homology to the zinc-binding domain of DNA (cytosine-5) methyltransferases (EC 2.1.1.63). Sequence analysis of the murine All-1 gene has identified distinct regions of homology with the human ALL-1 gene; these highly conserved domains may define regions of functional significance in mammals. In addition, we have identified alternatively spliced forms of All-1 within one of the zinc-finger domains, suggesting that there may be different targets and/or functions for All-1 proteins. Finally, we report that All-1 resides in the proximal portion of mouse chromosome 9 and is a candidate for a mutation that results in skeletal transformations during embryonic development.

[Fermentation of engineered strain producing cholera toxin B subunit]

Studies indicate that the cholera B subunit could be synthesized efficiently in corn steep liquor by engineered E. coli strain MM2. We have also determined the optical density, pH and the yield of B subunit kinetically during fermentation. Corn steep liquor medium has advantages in low cost, simplicity in technological process and high yield of B subunit which can reaches 40 micrograms/ml in 50L fermentative tank.

[Hurler syndrome (a case report)]

A case of Hurler syndrome diagnosed by clinical and laboratory examination is reported. The patient's roentgenograms showed the dystrophies of bones, lace-shaped ribs, boat-shaped cranium, fishhook-shaped forefront protrusion of silla trucica. Corneal opacities and high ocular pressure were found in both eyes. VEP measurement suggested the defects of optic nerve. The authors emphasized that visual electric physiological examinations should be used to estimate the visual functions when the patient's refractive medium is opqaue. The differential diagnosis was also briefly discussed.

Effects of phenethyl isothiocyanate, a carcinogenesis inhibitor, on xenobiotic-metabolizing enzymes and nitrosamine metabolism in rats

Phenethyl isothiocyanate (PEITC), a constituent of cruciferous vegetables, has been shown to inhibit chemical carcinogenesis, possibly due to its ability to block the activation or to enhance the detoxification of chemical carcinogens. The present study was conducted to elucidate the biochemical mechanisms involved by characterizing the effects of PEITC on phase I and phase II xenobiotic-metabolizing enzymes. A single dose of PEITC to F344 rats (1 mmol/kg) decreased the liver N-nitrosodimethylamine demethylase (NDMAd) activity (mainly due to P450 2E1) by 80% at 2 h and the activity of NDMAd remained decreased by 40% at 48 h after treatment. The liver pentoxyresorufin O-dealkylase (PROD) activity and P450 2B1 protein level were elevated 10- and 7-fold at 24 h after treatment respectively. The liver microsomal ethoxyresorufin O-dealkylase (EROD) (mainly due to P450 1A) and erythromycin N-demethylase (mainly due to P450 3A) activities were decreased at 2-12 h after treatment and recovered afterwards. The lung microsomal PROD and EROD activities were not significantly affected; whereas, the nasal microsomal PROD and EROD activities were decreased by 40-50%. After a treatment with PEITC, the rates of oxidative metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were decreased in liver microsomes by 40-60% at 2 h and recovered gradually; the rates in lung microsomes were markedly decreased by 60-70% at 2 h and remained at the decreased level at 24 h; and the rates in nasal mucosa microsomes were decreased gradually with the lowest activities observed at 18 h (50%) followed by a gradual recovery. Furthermore, the treatment with PEITC resulted in a maximal 5-fold increase of NAD(P)H:quinone oxidoreductase and 1.5-fold increase of glutathione S-transferase activities in the liver, but the activities of these two enzymes were not significantly affected in the lung and nasal mucosa. The sulfotransferase activity in the liver was decreased by 32-48% at 24-48 h after treatment; the nasal activity was increased by 1.8- to 2.5-fold, but the lung activity was not significantly changed. The hepatic UDP glucuronosyltransferase activity was slightly decreased at 2 h but slightly increased at 48 h after treatment, but no changes were observed for the lung and nasal activities. The study demonstrates that PEITC selectively affects xenobiotic-metabolizing enzymes in the liver, lung and nasal mucosa and it is especially effective in inhibiting the P450-dependent oxidation of NNK in the lung and of NDMA in the liver.

Identification of a glycine-rich sequence as an NAD(P)H-binding site and tyrosine 128 as a dicumarol-binding site in rat liver NAD(P)H:quinone oxidoreductase by site-directed mutagenesis

Site-directed mutagenesis was utilized to identify binding sites for NAD(P)H and dicumarol in rat liver NAD(P)H:quinone oxidoreductase (NQOR, EC 1.6.99.2). The mutant cDNA clones were generated by a procedure based on the polymerase chain reaction and were expressed in Escherichia coli. The mutant enzymes were purified to apparent homogeneity as judged by SDS-polyacrylamide gel electrophoresis and were found to contain 2 FADs/enzyme molecule identical with that of the wild-type NQOR. Purified mutant enzymes Y128D, G150F, G150V, S151F, and Y155D showed dramatic decreases in activities in the reduction of dichlorophenolindophenol in comparison with the activities of the wild-type enzyme, whereas the activities of F124L, T127V, T127E, Y128V, Y128F, S151A, and Y155V were similar to those of NQOR. Enzyme kinetic analysis revealed that the Km values of T127E, Y128D, G150F, G150V, S151F, and Y155D were, respectively, 4-, 2-, 13-, 5-, 26-, and 19-fold higher than the Km of NQOR for NADPH, and were, respectively, 2-, 3-, 7-, 3-, 20-, and 11-fold higher than that of NQOR for NADH. The kcat values of Y128D, G150F, and G150V were also much lower than those of NQOR, but the kcat values of other mutants were similar to those of the wild-type enzyme. The Km values of the mutants for dichlorophenolindophenol were the same or slightly higher than that of NQOR. The apparent inhibition constants (Ki) for dicumarol on Y128V and F124L were elevated 12 and 8 times, respectively. Similar, but smaller, changes on Ki for 4-hydroxycoumarin were also observed. This study demonstrated that residues Gly150, Ser151, and Tyr155 in the glycine-rich region of NQOR are essential for NADPH and NADH binding and Tyr128 is important for dicumarol binding. Based on the results of the study, it is proposed that the glycine-rich region of the enzyme, along with other residues around the region, forms a beta sheet-turn-alpha helix structure important for the binding of the pyrophosphate group of NADPH and NADH.

Retinoma and phthisis bulbi of retinoblastoma. 1. Clinical and genetic analysis

Retinoma and phthisis bulbi of retinoblastoma are rare entities found in retinoblastoma patients and their relatives. Eleven cases of phthisis bulbi of retinoblastoma and 9 cases of retinoma were identified from 1966 to 1991 in our center. The clinic data show that retinoma and phthisis bulbi are closely related to the retinoblastoma gene. Enucleation should be carried out as soon as possible without hesitation for the phthisis of eyes with retinoblastoma. Genetic counseling and frequent observation should be paid attention to retinoma patients and their offspring. The mechanism of retinoma developed is discussed. We propose that the diversity of second mutation might be the cause of retinoma.

Site-directed mutagenesis of rat liver NAD(P)H: quinone oxidoreductase: roles of lysine 76 and cysteine 179

We previously reported the expression of a full-length cDNA complementary to a rat liver NAD(P)H:quinone oxidoreductase (EC 1.6.99.2) mRNA in Escherichia coli (Q. Ma, R. Wang, C. S. Yang, and A. Y. H. Lu, 1990, Arch. Biochem. Biophys. 283, 311-317). Since cysteine residues have been suggested to be important for the catalysis of flavoproteins and a lysine residue at position 76 in NAD(P)H:quinone oxidoreductase has been proposed to be involved in electron transfer of the enzyme, we investigated the roles of lysine 76 and cysteine 179 of this enzyme in catalysis by site-directed mutagenesis. Mutant cDNA clones replacing lysine 76 with valine (K76V) and cysteine 179 with alanine (C179A) were generated by a procedure based on the polymerase chain reaction. The mutant enzymes were expressed in E. coli. The cytosolic activities of the K76V and C179A mutants were 50 and 25% of that of the wild type (DTD), due to lower levels of the mutant proteins as shown by immunoblot analysis. The mutant proteins were purified to apparent homogeneity. The purified K76V and C179A mutant enzymes maintained full activities of 2,6-dichlorophenolindophenol (DCIP) reduction compared with that of the wild type. The mutant enzymes exhibited kinetic parameters for DCIP, NADH, and NADPH similar to those of DTD except that, with K76V, the Km for NADPH was doubled. Both mutant proteins contained two molecules of FAD per enzyme molecule. Dicumarol inhibited K76V and C179A mutant activities to greater than 90% at a concentration of 10(-7) M. Heat stability studies showed that C179A was much more sensitive to inactivation at 37 degrees C than both the wild-type and K76V enzymes. It is concluded from this study that lysine 76 and cysteine 179 are not essential in catalysis and in the binding of FAD, DCIP, and dicumarol. However, lysine residue 76 appears to play a role in NADPH binding and cysteine residue 179 is important in maintaining the stability of the enzyme.

The study of G6PD in erythrocyte and lens in senile and presenile cataract

The G6PD activity of erythrocytes in 113 male patients with senile and presenile cataract and 86 controls, and G6PD activity of lens in 30 patients with senile cataract and 42 controls were reported. The cataractous group had higher frequency of G6PD deficiency and lower average G6PD level in erythrocytes and lenses, but without statistical significance. The frequency of G6PD deficiency of erythrocytes in presenile cataractous group was higher than that of senile cataractous group but with no statistical significance too. However, the average G6PD level of erythrocytes in presenile cataractous group was lower than that of senile cataractous group and with statistical significance (P < 0.05). The G6PD activity of lenses only presenile in the cortex and have a positive correlation with that of erythrocytes. There was a case with deficiency of G6PD both of erythrocytes and cataractous lenses in both eyes. The results indicate that the deficiency of G6PD might be one of the cataractous pathogenetic factor for presenile cataract. Measurement of G6PD activity of erythrocytes among population might be of significance in finding the risk factor for cataract.

Detection of gene alteration for color vision defects by polymerase chain reaction

According to the fact that the abnormalities of visual pigment genes were always involved in the changing of the exon 5, two oligonucleotide primers were designed to amplify the exon 5 of red pigment gene and green pigment gene. After electrophoresis of the PCR products digested with Rsal or Sau3A, the DNA fragments from the exon 5 of red pigment gene (RPG) and green pigment gene (GPG) were separated since there are different restriction endonuclease sites. On the other hand, we analyzed the exon 5 related fragment by Southern blot hybridization with probe out of the 3' end of the fourth intron of green pigment gene. The results of PCR are consistent with nucleic acid hybridization. PCR technique will be of value in prenatal evaluation and genetic counselling.

[A clinical study and analysis of congenital lenticular dislocation (35 cases)]

Thirty-five cases of congenital lenticular dislocation seen in our Center since 1985 have been studied and analyzed clinically. By the survey of pedigrees and examination of these patients, including ocular, systemic, skeletal X-ray, psychocardiogram, and urinary sodium-nitroprusside test, 21 cases were diagnosed as Marfan's syndrome, 6 cases as simple ectopia lentis, 3 cases as Weill-Marchesani's syndrome, 4 cases as aniridia and 1 case as homecys tinuria. We found that the most significant ocular manifestation of congenital lenticular dislocation was reduction in visual acuity. The severity of visual disturbance varied with the types of dislocation and the visual deficiency was closely related to the intermediate-grade (II) dislocation of the lens. Examination of ERG showed normal function in most of the patients. From this, we believe that the major cause of visual reduction in congenital lenticular dislocation is lenticular myopia and astigmatism. There fore, early diagnosis and effective correction of vision should be emphasized to prevent the occurrence of amblyopia.

[Waardenburg syndrome]

We report a patient with Waardenburg syndrome. He suffers from congenital deafness and presents high broad nasal root, synophrys, iris heterochromia and fundus hypopigment. The dystopia canthus is absence. In his family pedigree analysis, we found that his second cousin has oculocutaneous albinism.

Abnormalities of ERG in congenital aniridia

Congenital aniridia is generally associated with nystagmus, corneal pannus, cataract, ectopia lentis, glaucoma, macular hypoplasia, optic nerve hypoplasia and compromised visual function. Many theories have been proposed, including a failure in the development of the neural ectoderm and/or an aberrant development of mesoderm. We observed the ERG from 19 patients with congenital aniridia. Fourteen patients had abnormal ERG, including the reduced a wave trough under dark adapted red stimuli with dark adaptation; abnormal a or/and b waves in dark or/and light adapted ERG or abnormal oscillatory potentials. The ERG abnormalities reflected the disturbances either in the outer retina such as photoreceptors or in the structures of inner retina. The preserved visual function and several ocular abnormalities show that the aniridia may be a consequence of several pathogenetic mechanisms. This fact supported the opinion that congenital aniridia would be a concurrent failure of both ectoderm and mesoderm in embryonate development.

A corrected sequence for the predicted protein from the mitogen-inducible TIS11 primary response gene

We previously reported the sequence of a cDNA, TIS11, cloned from TPA-treated Swiss 3T3 cells. Two laboratories have reported sequences for cDNAs that have a region of identity with the TIS11 cDNA, but differ in their 5' and 3' flanking regions. We now report that the original TIS11 cDNA is likely to be a chimeric molecule, and find that the TIS11 gene encodes a protein identical to the TTP and Nup475 genes.

[Galactose-1-phosphate uridyl transferase and congenital cataract]

The activity of red blood cells galactose-1-p-uridyl transferase (GPUT) was determined by the spectrophotofluorometric method. The average GPUT activity in 102 control subjects was 13. 34 +/- 2. 03u. There were no differences in the sexes and ages. The average GPUT activity in 108 patients with congenital cataract was 11.58 +/- 4. 03u and was lower than that of the controls (P < 0.01). The GPUT activity in 14 of the 108(12.96%)patients was all-3SD below the mean value of the controls (< 7.24u) and the range was from 4.02u to 7.13u with the mean value of 5. 93u being about 44.45% of the normal. The difference between the two groups was statistically significant (P < 0.001). The results indicated that some of the patients with congenital cataract were due to decrease in the GPUT activity. The patients with decrease GPUT activity were mainly suffering from cataracts and their systemic disease were mild.

[Molecular cloning of lipopolysaccharide genes of the Vibrio cholerae in E. coli HB101]

A genomic library of the V. cholerae 178 (Eltor biotype, Ogawa serotype) was constructed by using cosmid pHC 79 as a cloning vector. We screened the library with immune agglutination test and colonies solid phase ELISA. 13 positive recombinants which could express the O antigen of the V. cholerae lipopolysaccharide (LPS) were acquired. The LPS was then extracted from a positive recombinant PMM-VO 38 by using hot phenol-water method. It was found that purified LPS specifically reacted to antisomatic serum against the V. cholerae. The restriction endonucleases analysis showed that the molecular weight of the recombination cosmid PMM-VO 38 was about 46 kb.

[Analysis of the circulating immune complexes in experimental lens-induced uveitis]

The authors isolated the circulating immune complexes in experimental lens-induced uveitis by PEG-6000 precipitation and molecular filtration in two peaks. ELISA showed that Peak I was a fraction of antigens comprising four components of soluble lens crystallin, of which gamma-crystallin was the most abundant, but no soluble antigens of the retina; Peak II was the antibodies corresponding to Peak I. SDS electrophoresis demonstrated the presence of over 10 antigen-antibody complexes. The results proved that the toxic complexes of experimental lens-induced uveitis was the lens crystallin immune complexes, and further suggested that gamma-crystallin immune complexes induced experimental uveitis as well as the alpha- and beta-crystallin immune complexes.

[Visual pigment genes for color vision defects]

Applying recombinant DNA techniques, the structures of red pigment gene (RPG) and green pigment gene (GPG) were analyzed for 43 patients with protan or deutan (including 3 females), 4 normal relatives and 3 carriers out of 3 families, as well as 11 normal controls. Abnormality of RPG was detected in all 19 protan and that of GPG was found in 14 out of 24 deutan. In about 80% (32/40) of protan and deutan the changing of exon 5 for RPG or GPG was discovered. In protan the normal RPG was replaced by a 5' red -3' green hybrid gene. Some of the deutan had no GPG, some had 5' green -3' red hybrid gene with or without GPG. Furthermore, the exon 5 of RPG and GPG was amplified by polymerase chain reaction (PCR) and further analyzed by Rsa I digestion. The results for PCR are identical to that of Southern blot hybridization.

Expression of mammalian DT-diaphorase in Escherichia coli: purification and characterization of the expressed protein

A full-length cDNA clone, pKK-DTD4, complementary to rat liver cytosolic DT-diaphorase [NAD(P)H:quinone oxidoreductase (EC 1.6.99.2)] mRNA was expressed in Escherichia coli. The pKK-DTD4 cDNA was obtained by extending the 5'-end sequence of a rat liver DT-diaphorase cDNA clone, pDTD55, to include an ATG initiation codon and the NH2-terminal codons using polymerase chain reaction (PCR). Restriction sites for EcoRI and HindIII were incorporated at the 5'- and 3'-ends of the cDNA, respectively, by the PCR reaction. The resulting full-length cDNA was inserted into an expression vector, pKK2.7, at the EcoRI and HindIII restriction sites. E. coli strain AB1899 was transformed with the constructed expression plasmid, and DT-diaphorase was expressed under the control of the tac promotor. The expressed DT-diaphorase exhibited high activity of menadione reduction and was inhibited by dicumarol at a concentration of 10(-5)M. After purification by Cibacron Blue affinity chromatography, the expressed enzyme migrated as a single band on 12.5% sodium dodecyl sulfate-polyacrylamide gel with a molecular weight equivalent to that of the purified rat liver cytosolic DT-diaphorase. The purified expressed protein was recognized by polyclonal antibodies against rat liver DT-diaphorase on immunoblot analysis. It utilized either NADPH or NADH as electron donor at equal efficiency and displayed high activities in reduction of menadione, 1,4-benzoquinone, and 2,6-dichlorophenolindophenol which are typical substrates for DT-diaphorase. The expressed DT-diaphorase exhibited a typical flavoprotein spectrum with absorption peaks at 380 and 452 nm. Flavin content determination showed that it contained 2 mol of FAD per mole of the enzyme. Edman protein sequencing of the first 20 amino acid residues at the NH2 terminus of the expressed protein indicated that the expressed DT-diaphorase is not blocked at the NH2 terminus and has an alanine as the first amino acid. The remaining 19 amino acid residues at the NH2 terminus were identical with those of the DT-diaphorase purified from rat liver cytosol.

[Visual pigment genes for color vision defects]

Applying recombinant DNA techniques, the structures of red pigment gene (RPG) and green pigment gene (GPG) were analyzed for 43 patients with protan or deutan (including 3 females), 4 normal relatives and 3 carriers out of 3 families, as well as 11 normal controls. Abnormality of RPG was detected in all 19 protan and that of GPG was found in 14 out of 24 deutan. In about 80% (32/40) of protan and deutan the changing of exon 5 for RPG or GPG was discovered. In protan the normal RPG was replaced by a 5' red -3' green hybrid gene. Some of the deutan had no GPG, some had 5' green -3' red hybrid gene with or without GPG. Furthermore, the exon 5 of RPG and GPG was amplified by polymerase chain reaction (PCR) and further analyzed by Rsa I digestion. The results for PCR are identical to that of Southern blot hybridization.

[Primary study of iontophoresis of zinc ion in treatment of retinitis pigmentosa]

We report here the preliminary effects of zinc iontophoresis in treatment of 26 Rp patients who had decreased zinc serum level or abnormal ratio of serum copper to zinc. Through more than 20 to 30 times of therapy, the vision of 15.38% eyes increased more than "3 lines", 4% eyes increased more than 5 degrees in the visual field, 13.46% eyes improved in dark adaptation threshold (greater than 1.0), the visual functions of the rest eyes were slightly improved or unimproved. The fundus didn't change before & after treatment. There were no changes of ERG in 8 eyes of 4 cases. In addition, the advantages and disadvantages between Zn iontophoresis and Zn compound taken orally, the improvement of vision by direct electric current therapy, the relationship between the metabolism of Zn element and Vit A and influence of Zn over the mechanism of dark adaptation were also briefly discussed.

Similarities and differences in the regulation of hepatic cytochrome P-450 enzymes by diabetes and fasting in male rats

The effects of streptozotocin-induced diabetes and fasting on hepatic cytochrome P-450 enzymes in sexually mature male rats were studied by immunochemical techniques and enzyme assays. The level of cytochrome P-450ac (an acetone/ethanol inducible form), 65 pmol/mg microsomal protein in control rats, increased 4- to 5-fold in diabetic rats and 3- and 5-fold in fasting rats. In contrast, P-450 UT-A (a male specific form) decreased drastically from 295 pmol/mg in the control group to about 10% of this value in diabetic rats and to 50% in fasting rats. P-450 PCN-E (a 16 alpha-cyanopregnenolone/dexamethasone inducible form), on the other hand, decreased from 151 pmol/mg to 38% in diabetic rats and increased 2-fold in fasting rats. These changes were also reflected in catalytic activities using N-nitrosodimethylamine, benzphetamine, and erythromycin as substrates. Slight changes in cytochromes P-450 UT-F, P-450 UT-I and P-450 PB-C were also observed under these conditions, but the biological significance is not known. These results suggest that different mechanisms exist for the regulation of the expression of cytochrome P-450 enzymes in diabetic and fasting rats.

[One stage resection of esophageal cancer and pulmonary bulla--a report of three patients]

Since 1982, three patients with esophageal cancer complicated with pulmonary bullae have been treated by operation on the esophagus and lung in one performance: In all the patients, the bullae were on the same side of the operation. The esophageal or cardiac cancer was resected first, then the bulla was treated. The site of esophago-gastric anastomosis was reinforced by the greater omentum. For mid-upper esophageal cancer, cervical anastomosis was done in order to avoid infection or leakage. In the third patient, pyopneumothorax occurred after wedge resection of a large bulla in the right upper lung and the surrounding tissues. The patient survived after timely drainage and medical management. The extent of resection for pulmonary bulla (bulla, segment or lobe) depends on the location, shape, size and number of the bullae and the pathological change in the surrounding tissues. We suggest that the indications: Cardio-pulmonary functions of the patient be stage II or better, even with mild emphysema so as they can tolerate anesthesia and surgery. Pulmonary function can be compensated after the lesion is removed, otherwise it is taken as a contraindication. The one stage removal of two foci makes it possible to avoid postoperative complications.