Biomedical subjects

M Y Liu

Publications and source records attributed to M Y Liu.

At least 55 records · Page 3Linked to original sources

PubMed1999

Morphological changes of spermatozoa in proximal vas deferens after vasectomy.

AIM: To investigate the morphological changes of spermatozoa in the proximal vas deferens after vasectomy. METHODS: Proximal vas deferens fluids were collected from 79 fertile men (group A) and 64 vasectomized men (group B) during the operations of vasectomy or vasovasostomy. Sperm morphology in the proximal vas deferens was analyzed after staining with the modified Papanicolaou method. RESULTS: The percentage of spermatozoa with a normal oval head from group B (50. 7% +/- 21.7%) was significantly lower than that of group A (75.2% +/- 11.1%). The data in group A was similar to those of normal semen and therefore represents the physiological condition of the proximal vas deferens sperm of fertile men. There were no significant differences in the percentages of normal oval heads in group B with the time since vasectomy. CONCLUSION: After vasectomy, the spermatozoa in the proximal vas deferens and epididymis were continuously degenerating and being replenished by spermatozoa coming from testis. The obvious morphological degeneration occurred in the sperm tail and spermatozoa with a small oval head and amorphous heads were increased.

Adult↗

PubMed1998

Defective LPS signaling in C3H/HeJ and C57BL/10ScCr mice: mutations in Tlr4 gene.

Mutations of the gene Lps selectively impede lipopolysaccharide (LPS) signal transduction in C3H/HeJ and C57BL/10ScCr mice, rendering them resistant to endotoxin yet highly susceptible to Gram-negative infection. The codominant Lpsd allele of C3H/HeJ mice was shown to correspond to a missense mutation in the third exon of the Toll-like receptor-4 gene (Tlr4), predicted to replace proline with histidine at position 712 of the polypeptide chain. C57BL/10ScCr mice are homozygous for a null mutation of Tlr4. Thus, the mammalian Tlr4 protein has been adapted primarily to subserve the recognition of LPS and presumably transduces the LPS signal across the plasma membrane. Destructive mutations of Tlr4 predispose to the development of Gram-negative sepsis, leaving most aspects of immune function intact.

Amino Acid Sequence↗

PubMed1998

The C-terminal segment is essential for maintaining the quaternary structure and enzyme activity of the nitric oxide forming nitrite reductase from Achromobacter cycloclastes.

We have constructed and expressed a series of mutated nitrite reductase (NIR) mutants based on the sequence of NIR from Achromobacter cycloclastes. Deleting a pentapeptide, an undecapeptide, or a heptadecapeptide from the C-terminus of NIR resulted in a series of C-terminal deletion mutated proteins designated as NIR-5, NIR-11, and NIR-17, respectively. A C-terminally extended mutated protein, NIR+8, was also produced, which contains an extra octapeptide attached to the C-terminus of the wild-type NIR. An SDS-PAGE system using tris-tricine buffer could retain the native NIR in its trimeric form, thus offering a convenient method to check the quaternary structure of NIR analogs. By using this system it was found that NIR-5 was maintained as trimer and retained 72% of wild-type enzyme activity. However, both NIR-11 and NIR-17 behaved as monomers in the SDS-PAGE and lost all their enzyme activity. Although NIR+8 maintained its trimeric structure it was enzymatically inactive. These results clearly indicate that the C-terminal undecapeptide is essential for maintaining the quaternary structure as well as the full enzymatic activity, as expected from the X-ray crystallography studies.

Alcaligenes↗

PubMed1998

Lead-induced changes in spermatozoa function and metabolism.

The relationships between sperm reactive oxygen species (ROS) generation, the capacitation process and acrosome reaction, and the spermoocyte penetration rate (SOPR) were investigated to understand the effect of lead toxicity on sperm functions and the mechanisms of these effects. Male Sprague-Dawley rats received weekly intraperitoneal injections of 20 mg or 50 mg lead acetate/kg or 20 mg or 50 mg sodium acetate/kg (control) for 6 wk. Serum testosterone was measured by radioimmunoassay. In cauda epididymal spermatozoa, the chemiluminescence was measured to evaluate the sperm ROS generation. Chlortetracycline fluorescence assay was used to study the status of capacitation and acrosome reaction on fresh cauda epididymal spermatozoa and after 2, 4, or 24 h of incubation with 5 mg/ml bovine serum albumin. In lead-exposed rats, the serum testosterone levels were reduced, and the percentage of capacitation and the chemiluminescence were significantly increased in fresh cauda epididymal spermatozoa. The serum testosterone levels were negatively associated with the percentage of acrosome-reacted spermatozoa. Sperm chemiluminescence was positively correlated with the percentage of both capacitated and acrosome-reacted spermatozoa. The SOPR was negatively associated with the percentage of both capacitated and acrosome-reacted spermatozoa. In summary, this study showed that male rats exposed to lead had decreased serum testosterone levels and that this metal produced early onset of capacitation by one of the pathways of ROS generation. These effects might consequently result in premature acrosome reaction and reduced zona-intact oocyte-penetrating capability.

Acrosome↗

PubMed1998

Effects of vitamin E and/or C on reactive oxygen species-related lead toxicity in the rat sperm.

This study was undertaken to investigate whether treatment with vitamin E (VE) and/or vitamin C (VC) protects rat sperm by inhibiting reactive oxygen species generation induced by lead (Pb) exposure. Male Sprague-Dawley rats were assigned to the following five groups: vitamin-unsupplemented; 150 mg VE/kg chow supplemented; 300 mg VE/kg chow supplemented; 500 mg VC/l drinking water supplemented and 150 mg VE/kg chow + 500 mg VC/l drinking water supplemented group. Rats in each group were divided into Pb-unexposed and Pb-exposed subgroups, received weekly intraperitoneal injection of 10 mg sodium acetate or 10 mg Pb acetate/kg for 6 weeks, respectively. The blood and sperm Pb levels were analyzed by graphite furnace atomic absorption spectrophotometer. Chemiluminescence was measured to evaluate the generation of sperm reactive oxygen species (ROS). Motility and sperm-oocyte penetration rate (SOPR) were measured. In Pb-unexposed rats, epididymal sperm counts, motility, ROS, and SOPR were not different in the five supplemented groups. Lead exposure might decrease the defense capacity of sperm to the oxidative stress and therefore elevate the ROS generation, reduce sperm motility, and reduce SOPR. Supplementation with VE and/or VC reduced ROS generation, prevented loss of motility and capacity of oocyte penetration in Pb-exposed rats. This study suggests that supplementation with VE and/or VC inhibits Pb-related ROS generation, protects spermatozoa from loss of motility and oocyte penetration capability.

Animals↗

PubMed1998

Characterisation of a new rubredoxin isolated from Desulfovibrio desulfuricans 27774: definition of a new family of rubredoxins.

A new rubredoxin from the sulphate-reducing bacterium Desulfovibrio desulfuricans ATCC 27774, grown with nitrate as terminal electron acceptor, was isolated and characterised. The protein is an 8.5 kDa monomer containing one iron atom per molecule, with a reduction potential of 25 +/- 5 mV at pH 7.6. Like the recombinant Rdl protein from D. vulgaris, expressed in Escherichia coli [Lumpio, H.L., Shenvi, N.V., Garg, R.P., Summers, A.O. and Kurtz, D.M., J. Bacteriol. 179 (1997) 4607-4615], it contains an unusual spacing of four amino acids between the first two of the iron coordinating cysteinyl residues. This difference is reflected in the structure of the iron centre, as observed by visible and EPR spectroscopies. All together, these features make these proteins the first members of a new family of rubredoxins.

Amino Acid Sequence↗

PubMed1998

Systemic chemotherapy alone for patients with non-acquired immunodeficiency syndrome-related central nervous system lymphoma: a pilot study of the BOMES protocol.

BACKGROUND: Anecdotal reports have suggested that systemic chemotherapy with agents that better cross the blood-brain barrier may result in long term disease remission in some patients with central nervous system (CNS) lymphoma. This treatment strategy has the advantage of sparing patients the late neurologic complications from brain irradiation. METHODS: Eligible patients were required to 1) have tissue-proven and measurable non-acquired immunodeficiency syndrome (AIDS)- related primary or metastatic CNS lymphoma; 2) have normal hemogram, renal function, and hepatic function; 3) be age < or = 75 years; and 4) have provided informed consent. Patients with lymphoblastic lymphoma or patients who previously had been exposed to nitrosoureas, etoposide, or high dose methotrexate were not eligible. The systemic chemotherapy (BOMES regimen) included carmustine, 65 mg/m2/day, intravenously (i.v.) on Days 1-2; vincristine, 2 mg/day, i.v. on Days 1 and 8; methotrexate, 1.5 g/m2, i.v. on day 15 followed by leucovorin rescue; etoposide, 50 mg/m2/day, i.v. on Days 1-5; and methylprednisolone, 200 mg/day, i.v. on Days 1-7; repeated every 4 weeks (BOMES regimen). Four doses of intrathecal methotrexate were given to patients who had involvement in the cerebrospinal fluid. RESULTS: Between March 1991 and March 1997 a total of 19 patients were enrolled on the study. There were 13 men and 6 women, with a median age of 57 years. Fourteen patients had primary CNS lymphoma and 5 patients had concurrent extra-CNS lymphoma. Nine patients previously had been treated by radiotherapy (four patients), chemotherapy (three patients), or both (two patients). There were 11 complete remissions (CR) (57.9%) and 5 partial remissions (26.3%), with a total remission rate of 84.2%. One patient had had progressive brain lymphoma during systemic chemotherapy with the conventional cyclophosphamide, doxorubicin, vincristine, and prednisolone regimen, but achieved CR soon after the regimen was changed to BOMES. The median time to progression of the responders was 6 months. At last follow-up, 4 patients were alive without lymphoma at 10, 47, 64, and 66 months, respectively. There were two treatment-related deaths due to sepsis. Another two patients died of fulminant hepatitis that most likely was chemotherapy-related reactivation of chronic B viral hepatitis. CONCLUSIONS: The authors believe systemic chemotherapy alone may result in long term disease remission in some select patients with non-AIDS-related CNS lymphoma. Further investigation for better protocols is mandatory.

Adult↗

PubMed1998

Distinct regions of EBV DNase are required for nuclease and DNA binding activities.

Epstein-Barr virus (EBV) DNase possesses both endonuclease and exonuclease activities and accepts both double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) as substrates. To map regions of EBV DNase responsible for nuclease and DNA binding activities, a series of mutant DNase polypeptides was expressed using a bacterial system for the nuclease assay and in an in vitro transcription/translation system to assay binding activity to dsDNA or ssDNA cellulose. The results indicated that the C-terminus of EBV DNase, residues 450-460, is essential for nuclease activity but dispensable for DNA binding. However, deletion of residues 441-470 resulted in the loss of both nuclease and DNA binding activities. Substitution of Phe452 and Val458 led to inactive enzymes. In the N-terminus, deletion of residues 23-28 and residues 7-61 resulted in the loss of nuclease activity but the DNA binding activities of the deleted enzymes were intermediate and low, respectively. Mutation of Leu23 to Gly showed drastically reduced nuclease activity but its DNA binding ability was not affected. Based on the amino acid sequence alignment of various herpesvirus DNases, we chose four highly conserved and two less well conserved regions as controls for mutagenesis studies. These six internal deletion (ID) mutants were prepared using a recombinant PCR method. Each of the polypeptides was expressed in a bacterial system for the nuclease assay and using an in vitro transcription/translation system for the DNA binding assay. DNA binding and nuclease activities of all six internal deletion mutants were abolished, except that mutant ID2, with deletion of residues 138-152, retained an intermediate ability to bind DNA. These data indicate that since mutations at distinct regions within EBV DNase resulted in the loss of nuclease and/or DNA binding activities, it is suggested that these distinct regions are required for maintenance of an intact and highly ordered structure(s) for both activities.

Amino Acid Sequence↗

PubMed1998

Antibody against the Epstein-Barr virus BHRF1 protein, a homologue of Bcl-2, in patients with nasopharyngeal carcinoma.

The Epstein-Barr virus (EBV) open reading frame BHRF1, a homologue of the oncogene bcl-2, was cloned from a patient with nasopharyngeal carcinoma (NPC) and overexpressed in Escherichia coli. The resulting recombinant BHRF1 fusion protein, with an apparent molecular weight of 35 KD, was used as antigen in an immunoblotting assay for IgG antibody in human sera. Anti-BHRF1 antibody was detected in 57 (61.3%) of 93 patients with NPC, 5 (5.7%) of 87 patients with nonmalignant diseases of the nasopharynx, and in 1 (1.3%) of 78 healthy blood donors. The positivity rate in these nonmalignant patients was 4.4 times that of the normal controls. Negative results were observed in four patients with infectious mononucleosis and patients with other cancers, including 4 with esophageal cancer, 11 with lung cancer, 10 with lymphoma, 13 with gastric carcinoma, 10 with cervical carcinoma, and 10 with other head and neck cancers. Antibody neutralizing EBV DNase and IgA antibody to viral capsid antigen (VCA) were assayed in parallel. The results showed that 7.5% of the NPC patients were negative for anti-DNase and anti-VCA antibodies and EBV infection could be detected by the anti-BHRF1 antibody alone. The demonstration of anti-BHRF1 antibody in most NPC sera strongly supports the hypothesis that the EBV BHRF1 protein is expressed in most NPC patients and its specific antibody can be a useful marker for the diagnosis of NPC.

Antibodies, Viral↗

PubMed1998

Effects of exposure to cypermethrin on saxitoxin binding in susceptible and pyrethroid-resistant houseflies.

Saxitoxin (STX) binding was measured in susceptible (SBO) and pyrethroid-resistant (KDR) female houseflies having only target site insensitivity as a resistance mechanism. In KDR flies, there was a quantitative decrease in STX binding capacity (Bmax) relative to SBO flies coupled with an increase in binding affinity (Kd). Treatment of SBO flies with sublethal doses of cypermethrin resulted in a large decrease in the number of STX binding sites and an increase in STX binding affinity. In KDR flies, identical treatments had the opposite effects. Treatment of both strains with higher doses of cypermethrin resulted in smaller decreases in Bmax values coupled with decreases in binding affinities. The results show that physiological changes in STX binding occur upon exposure to extremely low doses of cypermethrin. The data suggest that the kdr resistant gene may be expressed as changes in STX binding kinetics and that measurements of STX binding in pyrethroid-treated insects may be a useful approach for studying pyrethroid's mode of action and resistance.

Animals↗

PubMed1998

Genetic and physical mapping of the Lps locus: identification of the toll-4 receptor as a candidate gene in the critical region.

On the basis of 2093 meioses analyzed in two separate intraspecific backcrosses, the location of the mouse Lpsd mutation was circumscribed to a genetic interval 0.9 cM in size. A total of 19 genetic markers that lie in close proximity to the mutation were examined in mapping. Most of these were previously unpublished polymorphic microsatellites, identified by fragmentation of YAC and BAC clones spanning the region of interest. Lpsd was found to be inseparable from the microsatellite marker D4MIT178, and from three novel polymorphic microsatellites identified near D4MIT178. The mutation was confined between two novel microsatellite markers, herein designated "B" and "83.3." B lies centromeric to the mutation, and was separated by four crossovers in a panel of 1600 mice; 83.3 lies distal to the mutation and was separated by three crossovers in a panel of 493 mice. 66 BAC clones and one YAC clone were assembled to cover > 95% of the critical region. Estimates based on pulsed field gel electrophoresis and fluorescence in situ hybridization indicate that the The B-->83.3 interval is about 3.2 Mb in length. A minimal area of zero recombinational distance from Lpsd was also assigned, and found to occupy approximately 1.2 Mb of physical size. To identify gene candidates, nearly 40,000 sequencing runs were performed across the critical region. Selective hybridization and exon trapping were also employed to identify genes throughout the "zero" region. Only a single intact gene was identified within the entire critical region. This gene encodes the Toll-4 receptor, a member of the IL-1 receptor family.

Animals↗

PubMed1998

Belladonna alkaloids-induced behavioral changes and amnesia on open-field and step-through in 18-, 28-, and 38-day-old mice.

AIM: To study the age-related changes of atropine (Atr), scopolamine (Sco), anisodine (AT3), and anisodamine (Ani) on behaviors and memories. METHODS: The behaviors and memories were measured with open-field test and step-through task. M-cholinergic receptors were determined by [3H] quinuclidinyl benzilate ([3H] QNB). RESULTS: During acquisition session (d 1) the 18-, 28-, and 38-d-old mice pretreated with Atr, Sco, and AT3 (0.02, 0.2, 2, or 20 mg.kg-1, i.p.) in open-field test showed increase in walking counts by 26%-42%, but decrease in rearing, grooming, and defecating counts for 50%-92%, 67%-100%, and 75%-100%, respectively. On recall session (d 2) the walking and rearing behaviors in the 18- and 28-d-old mice receiving Atr, Sco, and AT3 on d 1 were higher than those in the mice receiving saline. But a lower grooming behavior on d 2 was found in the mice receiving the drugs on d 1. On d 1 Ani 20 mg.kg-1 reduced the rearing behavior by 50% in 18-d-old mice and defecation by 33%-36% in 18- and 28-d-old mice. All the 4 belladonna alkaloids increased the number of avoidance-response errors and decreased the retention latencies in step-through task. Bmax of [3H] QNB binding sites in frontal cortex and hippocampus regions in the 38-d-old mice increased 7% and 23% vs in the mice of 18 d of age, respectively. CONCLUSION: 1) The effects of the belladonna alkaloids on behaviors and memories in adult mice were weaker than those in young mice. 2) The belladonna alkaloids-induced amnesia on passive avoidance-response in step-through was more sensitive than behavioral changes and amnesia on open-field. 3) According to the lowest effective doses which insulted the behaviors or memories in young mice, Sco was about 10, 100, and 1000 times more potent than Atr, AT3, and Ani, respectively.

Age Factors↗

PubMed1997

Lead exposure causes generation of reactive oxygen species and functional impairment in rat sperm.

The relationships between blood lead, sperm lead, sperm reactive oxygen species (ROS) level, and sperm fertile capability were investigated to understand the effects of lead exposure on sperm function and the mechanism of these effects. Male Sprague-Dawley rats, 7 weeks old, were randomly divided into control group and lead-treated group. The controls and lead-treated animals received intraperitoneal injection of 10 mg sodium acetate and 10 mg lead acetate/kg body weight, respectively, weekly for 6 or 9 weeks. The blood lead and epididymal sperm lead were analyzed by graphite furnace atomic absorption spectrophotometer. Chemiluminescence was measured to evaluate the generation of sperm ROS. Sperm-oocyte penetration rate (SOPR) was measured to evaluate sperm function. After 6 weeks of lead exposure, the rats had average blood lead levels of 32 microg/dl, sperm lead levels of 0.67 +/- 0.11 microg/10(9) sperm, unchanged epididymal sperm counts, percent of motile sperms, and motile epididymal sperm counts compared with control animals. However, after 9 weeks of lead exposure, the rats had average blood lead levels of 48.0 +/- 4.3 microg/dl, sperm lead levels of 0.88 +/- 0.16 microg/10(9) sperm, statistically lower epididymal sperm counts, and lower motile epididymal sperm counts. There was a good correlation between the blood lead and sperm lead(r2 = 0.946, P < 0.001). The sperms of lead-exposed rats produced significantly higher counts ofchemiluminescence than did those from the control rats (P < 0.001). The chemiluminescence counts were positively associated with sperm lead level (r2 = 0.613, P < 0.001). Epididymal sperm counts, motility and motile epididymal sperm counts were negatively associated with sperm chemiluminescence (r2 = 0.255, 0.152, and 0.299; P < 0.01, 0.05, and 0.01, respectively). The SOPR were positively associated with epididymal sperm counts, motility and motile epididymal sperm counts (r2 = 0.136, 0.285, and 0.264; P < 0.05, 0.01, and 0.001, respectively). The sperm chemiluminescence was negatively associated with SOPR (r2 = 0.519, P < 0.001). It is concluded that lead exposure probably affected the sperm function by activating one of the pathways of ROS generation.

Animals↗

PubMed1997

Studies on the redox centers of the terminal oxidase from Desulfovibrio gigas and evidence for its interaction with rubredoxin.

Rubredoxin-oxygen oxidoreductase (ROO) is the final component of a soluble electron transfer chain that couples NADH oxidation to oxygen consumption in the anaerobic sulfate reducer Desulfovibrio gigas. It is an 86-kDa homodimeric flavohemeprotein containing two FAD molecules, one mesoheme IX, and one Fe-uroporphyrin I per monomer, capable of fully reducing oxygen to water. EPR studies on the native enzyme reveal two components with g values at approximately 2.46, 2.29, and 1.89, which are assigned to low spin hemes and are similar to the EPR features of P-450 hemes, suggesting that ROO hemes have a cysteinyl axial ligation. At pH 7.6, the flavin redox transitions occur at 0 +/- 15 mV for the quinone/semiquinone couple and at -130 +/- 15 mV for the semiquinone/hydroquinone couple; the hemes reduction potential is -350 +/- 15 mV. Spectroscopic studies provided unequivocal evidence that the flavins are the electron acceptor centers from rubredoxin, and that their reduction proceed through an anionic semiquinone radical. The reaction with oxygen occurs in the flavin moiety. These data are strongly corroborated by the finding that rubredoxin and ROO are located in the same polycistronic unit of D. gigas genome. For the first time, a clear role for a rubredoxin in a sulfate-reducing bacterium is presented.

Amino Acid Sequence↗

PubMed1997

Multiheme cytochromes from the sulfur-reducing bacterium Desulfuromonas acetoxidans.

Two new multiheme cytochromes were isolated from the anaerobic sulfur reducing bacterium Desulfuromonas acetoxidans. They have monomeric molecular masses of 50 and 65 kDa and contain six and eight hemes, respectively. Visible and EPR spectroscopies, in the as-isolated (oxidised) cytochromes, show the presence of only low-spin hemes in the 50-kDa cytochrome, and of high-spin and low-spin hemes in the 65-kDa cytochrome. The EPR spectra of the native 65-kDa cytochrome indicate multiple heme-heme interactions, including integer-spin systems as judged by parallel-mode EPR. The 50-kDa cytochrome has a complex redox pattern, as shown by EPR redox titrations, and contains one heme with unusual characteristics. Both cytochromes cover an extremely wide range of reduction potentials, which go from +100 mV to -375 mV for the 50-kDa cytochrome, and +185 mV to -235 mV for the 65-kDa cytochrome. The two cytochromes were tested for hydroxylamine oxidoreductase activity and polysulfide reductase activity, but neither displayed any activity. In contrast, it was found for the first time that the previously characterised cytochrome c551.5, from the same bacterium is very active in the reduction of polysulfide, which suggests that it acts as a terminal reductase in D. acetoxidans.

Amino Acid Sequence↗

PubMed1997

The RNA molecule CsrB binds to the global regulatory protein CsrA and antagonizes its activity in Escherichia coli.

The RNA-binding protein CsrA (carbon storage regulator) is a new kind of global regulator, which facilitates specific mRNA decay. A recombinant CsrA protein containing a metal-binding affinity tag (CsrA-H6) was purified to homogeneity and authenticated by N-terminal sequencing, matrix-assisted laser desorption/ionization time of flight mass spectrometry, and other studies. This protein was entirely contained within a globular complex of approximately 18 CsrA-H6 subunits and a single approximately 350-nucleotide RNA, CsrB. cDNA cloning and nucleotide sequencing revealed that the csrB gene is located downstream from syd in the 64-min region of the Escherichia coli K-12 genome and contains no open reading frames. The purified CsrA-CsrB ribonucleoprotein complex was active in regulating glg (glycogen biosynthesis) gene expression in vitro, as was the RNA-free form of the CsrA protein. Overexpression of csrB enhanced glycogen accumulation in E. coli, a stationary phase process that is repressed by CsrA. Thus, CsrB RNA is a second component of the Csr system, which binds to CsrA and antagonizes its effects on gene expression. A model for regulatory interactions in Csr is presented, which also explains previous observations on the homologous system in Erwinia carotovora. A highly repeated nucleotide sequence located within predicted stem-loops and other single-stranded regions of CsrB, CAGGA(U/A/C)G, is a plausible CsrA-binding element.

Bacterial Proteins↗

PubMed1997

Further evidence of no association between Ser9Gly polymorphism of dopamine D3 receptor gene and schizophrenia.

Dopamine D3 receptor (DRD3) was demonstrated to have important implications in schizophrenia, because it binds antipsychotic drugs and is abundant in the limbic system of the brain. Several groups attempted to find an association between a serine-to-glycine polymorphism at codon 9 of the DRD3 gene (Ser9Gly) and schizophrenia; however, the results were inconsistent. We conducted a case-control association study in Han Chinese schizophrenic patients from Taiwan, to examine the relationship of this serine-to-glycine polymorphism and schizophrenia. We noted no significant differences of genotype distribution, allele frequencies, or homozygosity proportion of this polymorphism between schizophrenic patients (N = 178) and controls (N = 100). When patients were divided according to sex, or presence or absence of family history, the differences were still not significant. Our study does not support the contention that the Ser9Gly polymorphism of the DRD3 gene plays a major role in schizophrenia.

Alleles↗

PubMed1997

Microbial and plant metabolism of NO.

During microbial denitrification, NO is produced by reduction of nitrite by either the reduced high spin d1 hemes in a unique reductase (NIR) or at the expense of a blue copper protein that transfers electrons that move first to a type I copper and then to a type II copper in a unique trimeric NIR. This latter type of NIR is also produced by several denitrifying filamentous fungi. Reduction of NO is then carried out by either a specific cytochrome be complex NOR in denitrifying bacteria or a unique cytochrome P-450 in denitrifying filamentous fungi. NO is also produced by an anomalous reaction of a molybdoprotein, nitrate reductase (NAR), acting on an odd substrate, NO2-. NO is also reduced by a multiheme NIR that serves physiologically for reduction of NO2- to NH3. This type NIR reduces NO to either N2O, if only partially reduced, or NH3, if fully reduced, when it encounters NO. This multiheme NIR is very sensitive to cyanide. Transcription of the genes for NIR and NOR production in a denitrifier is activated by NO, a process that also requires the presence of the gene product, a transcriptional activator, NnrR.

Bacteria↗