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Biomedical subjects

C H Zou

Publications and source records attributed to C H Zou.

10 recordsLinked to original sources
PubMed1999

Molecular cloning and characterization of a locus responsible for O acetylation of the O polysaccharide of Legionella pneumophila serogroup 1 lipopolysaccharide.

Complementation experiments, Tn5 mutagenesis, and DNA sequencing were used to identify a locus (lag-1) that participates in acetylation of Legionella pneumophila serogroup 1 lipopolysaccharide. Nuclear magnetic resonance analyses of lipopolysaccharides from mutant and complemented strains suggest that lag-1 is responsible for O acetylation of serogroup 1 O polysaccharide.

Acetylation↗
PubMed1997

Epilepsy and mental retardation limited to females: an X-linked dominant disorder with male sparing.

Several X-linked disorders affect females disproportionately or exclusively. These including focal dermal hypoplasia, oral-facial-digital syndrome type I (ref. 3) and epilepsy with bilateral periventricular heterotopias. X-linked dominant inheritance with male lethality is probably responsible for sex-limited expression of these disorders, as affected women have frequent spontaneous abortions and the sex ratio of their live offspring is often skewed. The same inheritance pattern has been proposed for Rett syndrome, Aicardi syndrome and microphthalmia with linear skin defects, but in these sporadic conditions, evidence of male lethality is lacking. We investigated an unusual family with epilepsy and mental retardation limited to females (EFMR, #121250 in ref. 9); this disorder is transmitted both by females and by completely unaffected carrier males. Assignment of the EFMR disease locus (EFMR) to the X chromosome indicates that selective involvement of females in X-linked disease may in some instances result from male sparing rather than male lethality.

Cerebral Cortex↗
PubMed1995

[Correlation between kidney deficiency syndrome and bone density].

In order to study the relationship between Kidney Deficiency Syndrome (KDS)and bone density (BD), the BD of 2068 subjects (40-69 years old)was measured with SPA-IIC type monophoton BD scanning device made in China. The subjects including 1144 cases of KDS (320 males and 824 females); 608 cases without KDS (306 males and 302 females); 164 cases of Lung Deficiency (80 males and 84 females); 152 cases of Spleen Deficiency (76 males and 76 females). Through comparison with the same sex and age group, it was found that BD in KDS patients was significantly lower than that in the normal subjects and those without KDS, also lower than that in the Lung and Spleen Deficiency patients. It indicated that KDS had the corresponding BD changes, which confirmed the TCM classical theory "The Kidney governs the bone". Based on the measuring data, the authors took the lower limit of BD normal value minus two folds of SD as the critical value for KDS diagnosis in 40-49 years age group, i. e., male BD < 0.6 g/cm2, female BD < 0.5 g/cm2. The clinical feedback showed that the male and female related coincident rates were 76% and 80% respectively. Therefore, the critical value could be taken as an objective index for KDS diagnosis after excluding other affecting factors.

Adult↗
PubMed1993

Schrodinger equation, Maxwell-Bolzmann distribution and a single channel current.

The dual nature, wave and particle, of ions in the biological system was considered. A theoretical model, based on the steady state Schrodinger equation and Maxwell-Bolzmann distribution of energy, is proposed to describe passive transport of ions through a biological membrane channel in a time independent field. Constant height (V2) and length(L) of the potential energy barrier and effective mass of ions are used in the model. This model shows that an ion may go through or be reflected from a channel whether its energy is lower or higher than the barrier. This is a departure from classical theory. Based on a published I-Vm (channel current-transmembrane voltage) curve from an activated K+ channel in a human erythrocyte membrane [Palle Christophersen, 1991], calculations with our model show that more than 99% of the channel current is contributed by ions with higher energy than the potential barrier. The current can be amplified 10,000 times while V2 is reduced from 0.45 eV (channel closed) to 0.20 eV (channel opened) at Vm = 0.07 V. In contrast, the current changes only 1.5% while L is narrowed from 90 A to 30 A at Vm = 0.07 V, V2 = 0.20 eV. The energy barrier: V2 = 0.16 + 0.43 Vm (eV), at r = 0.99, for 0.02 V < or = Vm < or = 0.12 V.

Biological Transport↗
PubMed1992

Isolation and characterization of a lipopolysaccharide mutant of Legionella pneumophila.

A mutant unable to bind a monoclonal antibody (mAb 1E6) directed against serogroup 1 lipopolysaccharide (LPS) was isolated from L. pneumophila strain Philadelphia-1. SDS-PAGE analysis of isolated LPS from the mutant and wild type revealed that there were no obvious structural differences between the two LPS. The results from Western-blot experiments showed that the mutant LPS was unable to bind mAb 1E6 but retained the ability to bind polyclonal serogroup 1 antibodies. Loss of the LPS epitope recognized by mAb 1E6 did not alter the ability of the mutant to multiply in human monocyte-like U937 cells. Also, the mutant, like wild type, was resistant to killing by normal human serum. These results show that a minor change in the antigenic composition of serogroup 1 LPS has no effect on the virulence properties of strain Philadelphia-1. Additionally, this mutant may be useful for molecular genetic analysis of serogroup 1 LPS biosynthesis and assembly.

Blood Bactericidal Activity↗
PubMed1992

Isolation and characterization of a conjugative plasmid from Legionella pneumophila.

The conjugative properties of an indigenous 85 MDa plasmid (designated pCH1) from Legionella pneumophila were studied. To determine if pCH1 was transmissible by conjugation, mating experiments were performed between legionellae that harboured pCH1 and several plasmid-less recipients. Plasmid transfer was monitored by colony hybridization, using a cloned 21.0 kb SalI restriction fragment from pCH1 as a probe. The results from these experiments showed that pCH1 could be conjugatively transferred into several strains of L. pneumophila serogroup 1 but not into strain Bloomington-2 (serogroup 3) or Escherichia coli. Southern hybridization experiments in which pCH1 DNA was used as a probe showed that pCH1 does not share homology with other indigenous L. pneumophila plasmids. There was no detectable DNA homology between pCH1 and L. pneumophila chromosomal DNA. Additional mating experiments revealed that pCH1 was unable to mobilize the L. pneumophila chromosome. The conjugative transfer of pCH1 into plasmid-less avirulent or virulent serogroup 1 strains did not alter the intracellular growth characteristics of these strains in U937 cells, a human-monocyte-like cell line, or in the amoeba Hartmannella vermiformis. These results suggest that pCH1 does not contribute to the ability of L. pneumophila to enter or grow within eukaryotic cells.

Cloning, Molecular↗
PubMed1992

Chromosome mobilization of Legionella pneumophila with RK2::Mu and Tn5-Mob.

RK2::Mu plasmids and transposon Tn5-Mob were used to mobilize the Legionella pneumophila chromosome. Plate matings between L. pneumophila donors that contained RK2::Mu plasmids and auxotrophic recipients yielded recombinants at frequencies ranging from 10(-6) to 10(-7) per recipient for the markers tested. The presence of a Mu insertion in the chromosome of donors that harbored RK2::Mu plasmids increased the frequency of chromosome transfer of certain selected markers as compared with strains that contained RK2::Mu alone. Cotransfer experiments with Mu-containing donors and a thymidine and tryptophan auxotroph failed to reveal any linkage between the thy and trp loci in L. pneumophila. A strain that contained a chromosomal Tn5-Mob insertion and helper plasmid pRK24.4 transferred chromosomal markers at frequencies of 10(-7) per recipient. These findings suggest that RK2::Mu plasmids and Tn5-Mob may be useful for genetic mapping experiments with L. pneumophila.

Blotting, Southern↗
PubMed1986

Etiologic and serologic investigations of the 1980 epidemic of dengue fever on Hainan Island, China.

Virologic and seroepidemiologic studies were carried out during an epidemic of dengue fever on Hainan Island in 1980. Dengue 3 virus was isolated from 46 of 77 acute phase sera and from 1 of 10 pools of adult Aedes aegypti. Dengue 1 virus virus was isolated from a single acute phase serum. Seroepidemiologic investigations showed that 74% of healthy individuals in the epidemic area had antibody to dengue virus compared to 54% in an area where epidemic dengue had occurred in 1978, and less than or equal to 8% in nonepidemic areas. There were no significant differences in antibody prevalence for different sex and age groups.

Aedes↗