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Biomedical subjects

X Zhao

Publications and source records attributed to X Zhao.

At least 379 records · Page 21Linked to original sources
PubMed1998

Taurine content in Chinese food and daily intake of Chinese men.

The taurine content in Chinese food, including seafood, fresh water fish, meats and some plants, was examined in this study. Seafood was freshly collected from 4 coastal areas in China. Meat and plant food samples were obtained from food markets. The highest concentration of taurine was found in crustaceans and molluses (300-800 mg per 100 g edible portion). The amount of taurine in fish was variable. Beef, pork and lamb contained taurine in concentrations ranging from 30-160 mg per 100 g. No taurine was detected in hen eggs and plants. The daily taurine intake of representative Chinese men (18-45 years old, 60 kg body weight, light physical activity) was also studied in 1990 as a part of the Total Diet Study. Representative food samples were collected from 12 provinces in 4 areas of China. Samples were then combined and cooked according to food categories (meat, seafood, vegetables, etc) The combined meat and seafood samples were analyzed for taurine. The daily taurine intake of a standard man in the 4 areas was calculated based on the amount of food intake obtained from the dietary survey and the taurine concentration in the analyzed food samples. The result showed that the daily taurine intake of a standard Chinese man in the 4 different test areas ranged from 34 to 80 mg per day.

Adolescent↗
PubMed1998

Preventive effect of different dosage of recombinant human erythropoietin on anemia of premature infants.

To assess the efficacy and the optimum dose of recombinant human erythropoietin (rhEpo) on the anemia of premature, 45 preterm infants with a gestational age of less than 35 weeks and birth weight of less 1,800 g were randomly assigned to treatment group 1 (n = 15, receiving subcutaneous rhEpo 150 U/kg.time), treatment group 2 (n = 15, receiving 250 U/kg.time), three times a week for 6 weeks, and control group (n = 15, no treatment was given). All preterm infants received supplements of vitamin E (20 IU) and iron (20 mg) each day. Our results showed that postnatal decline of hemoglobin (Hb) and hematocrit (Hct) were lessened in the treatment groups, particularly in the group 2 and the differences were very significant (P < 0.0001 for all). Treated infants had significantly higher reticulocyte counts (Ret) (P < 0.0001 for all), but there was no significant difference between the two treatment groups (P > 0.05). Serum iron dropped significantly in the treatment groups as compared with control group (P < 0.01 for all), but no dose-dependent relationship was observed in treated infants (P > 0.05). After treatment, serum levels of erythropoietin was higher in group 2 than those in group 1 and control group (P < 0.0001, P < 0.01 and P < 0.05, respectively). There was no significant difference between group 1 and control group (P > 0.05). No side effects related to rhEpo therapy were observed. Our study suggested that rhEpo therapy stimulates endogenous erythropoiesis and enhances Ret, Hct and level of Hb in a dose-dependent manner in premature infants. The therapy is more efficient when given in higher dosages.

Anemia, Iron-Deficiency↗
PubMed1998

Regulation of hypothalamic arginine vasopressin messenger ribonucleic acid and pituitary arginine vasopressin content in fetal sheep: effects of acute tonicity alterations and fetal maturation.

OBJECTIVE: Fetal arginine vasopressin contributes to fetal and amniotic fluid homeostasis by increasing water resorption in the kidney and, at higher plasma levels, circulatory homeostasis by vasopressor effects. In utero and neonatal exposure of rat pups to prolonged alterations in plasma osmolality may permanently alter (imprint) pituitary arginine vasopressin content and adult responses to osmotic challenges. Our objective was to investigate fetal developmental changes and the impact of maternal dehydration and maternal hyponatremia on fetal pituitary arginine vasopressin content and hypothalamic arginine vasopressin messenger ribonucleic acid expression. STUDY DESIGN: Ten pregnant ewes with singleton fetuses (135 +/- 1 day) were chronically prepared with maternal vascular catheters. Ewes were assigned to receive water deprivation (n = 4) [desamino, D-Arg8]-arginine vasopressin-induced plasma hyponatremia (n = 3), or 4 days of observation (n = 3). Three additional pregnant ewes with preterm (110 +/- 1 day) singleton fetuses were also included for a study of maturational effects. Daily maternal blood samples were analyzed for determination of plasma arginine vasopressin, electrolytes, and osmolality. After the study protocol, fetuses were operatively delivered, umbilical blood samples obtained, and fetuses put to death for pituitary and hypothalamic tissues. Pituitary arginine vasopressin content was determined by radioimmunoassay, and hypothalamus arginine vasopressin messenger ribonucleic acid expression was detected by Northern blotting. RESULTS: Dehydration significantly (P < .05) increased, and hyponatremia significantly decreased maternal plasma sodium concentration compared with controls. Fetal plasma sodium concentration significantly changed in parallel with maternal values (dehydration: 139 +/- 1 to 150 +/- 1 mEq/L; hyponatremia: 138 +/- 1 to 128 +/- 5 mEq/L). Fetal hypothalamic arginine vasopressin messenger ribonucleic acid expression and pituitary content did not change in relation to these relatively acute alterations in plasma tonicity. However, among all animals, arginine vasopressin messenger ribonucleic acid expression was significantly negatively correlated with pituitary arginine vasopressin content (r2 = 0.563; P = .02). Arginine vasopressin messenger ribonucleic acid expression was significantly lower in both preterm and near-term fetuses (P < .05) than that in the maternal ewe, although pituitary arginine vasopressin content (in micrograms per milligram of protein) was significantly greater in preterm fetuses (P < .01, vs maternal; P < .05, vs near term). CONCLUSIONS: The significant inverse relation between arginine vasopressin content and arginine vasopressin messenger ribonucleic acid suggests a dynamic arginine vasopressin synthesis-content feedback relationship is functional in the near-term fetus. Although relatively acute periods of maternal hypertonicity or hypotonicity do not alter fetal pituitary arginine vasopressin content or hypothalamic arginine vasopressin messenger ribonucleic acid expression, longer-term plasma tonicity alterations may potentially have an impact on the fetal arginine vasopressin hypothalamic-pituitary axis.

Animals↗
PubMed1998

Role of PKC and tyrosine kinase in ethanol-mediated inhibition of LPS-inducible nitric oxide synthase.

Ethanol increases human and animal susceptibility to opportunistic lung infections in part by suppression of endotoxin (LPS) and bacteria-mediated upregulation of inducible nitric oxide synthase (iNOS) in alveolar macrophages (AM). LPS and cytokine-induced NOS mRNA are dependent on NF-kappaB/Rel (NFkappaB) and Activator Protein-1 (AP-1), which are regulated in turn by protein kinase C and tyrosine kinase-dependent phosphorylation. ETOH does not directly inhibit NFkappaB or AP-1, in vivo, but rather inhibits LPS-induced activation of the MEKK/MAP kinase system and inhibition of inhibitory protein IkappaBalpha required for formation of AP-1 and NFkappaB, respectively. in AM. Both transcription factors are involved iNOS mRNA transcription. LPS-induced upregulation of MEKK/MAP tyrosine kinase upregulates NADPH oxidase activity and oxygen free radical formation required for activation of NFkappaB and AP-1 and phosphorylation of IkappaBalpha. LPS downregulates endogenous calcium-sensitive PKC isozymes (PKCdelta), which repress iNOS mRNA expression. ETOH inhibits LPS-induced upregulation of iNOS mRNA by preventing its ability to decrease PKCdelta and upregulate tyrosine kinase-mediated phosphorylation. This effect of ETOH is prevented by inhibitors of PKC and tyrosine kinase. The data support the hypothesis that ETOH inhibits LPS-induced upregulation of iNOS mRNA by interfering with the phosphorylation processes involved in activation of the nuclear transcription factors NFkappaB and AP-1.

Animals↗
PubMed1998

A suppressor of two essential checkpoint genes identifies a novel protein that negatively affects dNTP pools.

In Saccharomyces cerevisiae, MEC1 and RAD53 are essential for cell growth and checkpoint function. Their essential role in growth can be bypassed by deletion of a novel gene, SML1, which functions after several genes whose overexpression also suppresses mec1 inviability. In addition, sml1 affects various cellular processes analogous to overproducing the large subunit of ribonucleotide reductase, RNR1. These include effects on mitochondrial biogenesis, on the DNA damage response, and on cell growth. Consistent with these observations, the levels of dNTP pools in sml1 delta strains are increased compared to wild-type. This effect is not due to an increase in RNR transcription. Finally, both in vivo and in vitro experiments show that Sml1 binds to Rnr1. We propose that Sml1 inhibits dNTP synthesis posttranslationally by binding directly to Rnr1 and that Mec1 and Rad53 are required to relieve this inhibition.

Amino Acid Sequence↗
PubMed1998

Novel degradable poly(ethylene glycol) hydrogels for controlled release of protein.

Hydrogels have become increasingly important in the biomedical field. This paper describes synthesis and characterization of two types of novel degradable poly(ethylene glycol) (PEG) hydrogels with potential utility as delivery carriers for bioactive drugs. The simplest gel is prepared by one-step polycondensation of difunctional PEG acid and branched PEG "polyol". The second type of the novel degradable PEG hydrogel was prepared in a two-step process, in which an ester-containing, amine-reactive PEG derivative was synthesized and then reacted with a branched PEG amine to form the gel. The two-step gels are formed in very mild conditions, and therefore fragile drugs such as proteins can be loaded during gel formation. Because most proteins have free amino groups in the sequence, these proteins can be covalently linked to the hydrogel network. This covalent attachment provides a new way to achieve long-term controlled release of proteins. These hydrogels have a wide range of degradation rates. Upon hydrolysis, these PEG hydrogels will degrade into low molecular weight PEG derivatives, which can be easily cleared by the body.

Coloring Agents↗
PubMed1998

Macromolecular organization and genetic mapping of a rapidly evolving chromosome-specific tandem repeat family (B77) in cotton (Gossypium).

Isolation and characterization of the most prominent repetitive element families in the genome of tetraploid cotton (Gossypium barbadense L; [39]) revealed a small subset of families that showed very different properties in tetraploids than in their diploid progenitors, separated by 1-2 million years. One element, B77, was characterized in detail, and compared to the well-conserved 5S and 45S rRNA genes. The 572 bp B77 repeat was found to be concentrated in several discontinuous tandem arrays confined to a single 550 kb SalI fragment in tetraploid cotton. Genetic mapping based on the absence of the pentameric 'rung' in the G. barbadense 'ladder' showed that B77 maps to a D-subgenome chromosome. In situ hybridization supports the contention that the array is confined largely to a single chromosomal site in the D-subgenome. The B77 repeat has undergone a substantial increase in copy number since formation of tetraploid cotton from its diploid relatives. RFLPs observed among tetraploid cotton species suggest that amplification and/or rearrangement of the repeat may have continued after divergence of the five tetraploid cotton species. B77 contains many short direct repeats and shares significant DNA sequence homology with a Nicotiana alata retrotransposon Tna1-2 integrase motif. The recent amplification of B77 on linkage group D04 suggests that the D-subgenome of tetraploid cotton may be subject to different evolutionary constraints than the D-genome diploid chromosomes, which exhibit few genome-specific elements. Further, the abundance of B77 in G. gossypioides supports independent evidence that it may be the closest extant relative of the D-genome ancestor of cotton.

Base Sequence↗
PubMed1998

Immunoblot analyses of the relative contributions of cysteine and aspartic proteases to neurofilament breakdown products following experimental brain injury in rats.

Analyses using either one or two-dimensional gel electrophoresis were performed to identify the contribution of several proteases to lower molecular weight (MW) neurofilament 68 (NF68) break down products (BDPs) detected in cortical homogenates following unilateral cortical impact injury in rats. One dimensional immunoblot of BDPs obtained from in vitro cleavage of enriched neurofilaments (NF) by purified micro-calpain, m-calpain, cathepsin, B, cathepsin D, and CPP32 (caspase-3) were compared to in vivo samples from rats following traumatic brain injury (TBI). Comparison of these blots provided information on the relative contribution of different cysteine or aspartic proteases to NF loss following brain injury. As early as 3 hrs post-injury, cortical impact resulted in the presence of several lower MW NF68 immunopositive bands having patterns similar to those previously reported to be produced by calpain mediated proteolysis of neurofilaments. Only micro-calpain and m-calpain in vitro digestion of enriched neurofilaments contributed to the presence of the low MW 57 kD NF68 break down product (BDP) detected in post-TBI samples. Cathepsin B, cathepsin D, and caspase-3 failed to produce either the 53 kD or 57 kD NF BDPs. Further, 1 and 2 dimensional peptide maps containing a 1:1 ratio of in vivo and in vitro tissue samples showed complete comigration of lower MW immunopositive spots produced by TBI or in vitro incubation with m-calpain, thus providing additional evidence for the potential role of calpain activation to the production of NF68 BDPs following TBI. More importantly, 2-dimensional gel electrophoresis detected that immunopositive NF68 spots shifted to the basic pole (+) suggesting that dephosphorylation of the NF68 subunit pool may be associated with NF protein loss following TBI, an observation not previously noted in any model of experimental brain injury.

Animals↗
PubMed1998

Identification of a homophilic binding site in immunoglobulin-like domain 2 of the cell adhesion molecule L1.

The cell adhesion molecule L1 plays an important role in neural development, and mutations in human L1 have been implicated in X-linked hydrocephalus and related neurological diseases. We have previously demonstrated that recombinant proteins containing the second immunoglobulin-like domain (Ig2) of L1 contain both homophilic binding and neuritogenic activities. In this report, the involvement of L1 Ig2 in cell-cell adhesion and neuritogenesis was further evaluated in cell transfection studies. Transfectants expressing intact L1 were capable of undergoing L1-dependent self-aggregation and promoting neurite outgrowth from neural retinal cells. However, both activities were abolished in transfectants expressing L1delta2, a mutant L1 with Ig2 deleted. In competition experiments, the wild-type Ig2 fusion protein inhibited L1-dependent cell aggregation, whereas an Ig2 fusion protein containing the hydrocephalus mutation R184Q did not. Oligopeptides flanking Arg184 were therefore synthesized and assayed for their effects on L1-mediated cell-cell binding and neuritogenesis. The peptide L1-A, spanning the residues His178 and Gly191, inhibited both L1- and Ig2 fusion protein-mediated homophilic binding. When neural retinal cells were cultured on substrate-coated Ig2 fusion protein, peptide L1-A also abolished L1-dependent neurite outgrowth. Substitutions of several charged residues and hydrophobic residues with alanine in peptide analogues led to the loss of inhibitory effects, suggesting that multiple amino acids might be involved in L1-L1 binding. Taken together, these results identify an L1 homophilic binding site within the sequence HIKQDERVTMGQNG of Ig2 and demonstrate the requirement of L1 homophilic binding in the promotion of neurite outgrowth.

Animals↗
PubMed1998

EGF stimulates transcription of CaN19 (S100A2) in HaCaT keratinocytes.

CaN19 (S100A2), a member of the S100 family of calcium-binding proteins, was originally isolated in a screen for tumor suppressor genes. Recent work from our laboratory suggests that CaN19 is likely to be an effector of the regenerative hyperplasia pathway of epidermal differentiation. As other work from our laboratory in a human skin organ culture model suggests that this response is mediated by activation of the epidermal growth factor (EGF) receptor and/or related receptors of the ErbB family, we asked whether CaN19 expression could be increased by organ culture and by EGF treatment of human keratinocytes. CaN19 was strongly induced after 24 h of organ culture, and its induction could be blocked by PD153035, a specific inhibitor of EGF receptor tyrosine kinase activity. EGF treatment of immortalized human keratinocytes (HaCaT cells) increased CaN19 mRNA levels by 4.5-fold within 8 h, and a corresponding increase in CaN19 protein was observed by western blotting. EGF treatment had no effect on the expression of five other members of the S100A gene cluster. As assessed by nuclear run-off assay, CaN19 transcription increased rapidly in response to EGF, reaching a maximum induction of 16-fold after 2 h. In contrast, EGF treatment had no detectable effects on the decay of CaN19 transcripts, which were long lived (t1/2 > 6 h) in the presence or absence of EGF. PD153035 also blocked CaN19 transcription and the accumulation of CaN19 mRNA and protein in HaCaT cells. These results demonstrate that EGF receptor activation selectively stimulates CaN19 gene expression at the transcriptional level in human keratinocytes, and support the hypothesis that CaN19 is an important mediator of regenerative epidermal hyperplasia.

Calcium-Binding Proteins↗
PubMed1998

Risk factors for glioma in adults: a case-control study in northeast China.

A case-control study of risk factors for glioma in adults was carried out in Heilongjiang province in northeast China. Between September 1989 and May 1995, 218 histologically confirmed cases of glioma requiring surgery for tumor removal (139 astrocytoma glioma and 79 other glioma) and 436 controls with non-neoplastic and non-neurological disease were recruited and personally interviewed in the wards of six major hospitals. Controls were matched by sex, age, and area of residence. Occupational, lifestyle, and medical information was obtained through a standardized questionnaire. Use of liquor was associated with cancer risk. Compared with males who never drank liquor, males with total lifetime liquor consumption of less than 1000 liters had an adjusted odds ratio (OR) of 1.60 (95% CI: 0.89-2.88) and for more than 1000 liters, 2.73 (95% CI: 1.06-7.08). Statistically significant associations were also found for diseases related to the brain (OR: 5.75; 95% CI: 1.08-30.47) and trauma to the head requiring medical attention (OR: 4.09; 95% CI: 2.51-10.31). Increased consumption of vegetables and of fruit were each associated with decreased glioma risk. Compared with lowest quartile intake, adjusted risks associated with highest quartile intake were 0.51 (95% CI: 0.29-0.89) for total vegetables and 0.28 (95% CI: 0.16-0.51) for total fruit.

Adult↗
PubMed1998

The Arg-Gly-Asp motif in the cell adhesion molecule L1 promotes neurite outgrowth via interaction with the alphavbeta3 integrin.

The cell adhesion molecule L1 is a potent inducer of neurite outgrowth and it has been implicated in X-linked hydrocephalus and related neurological disorders. To investigate the mechanisms of neurite outgrowth stimulated by L1, attempts were made to identify the neuritogenic sites in L1. Fusion proteins containing different segments of the extracellular region of L1 were prepared and different neuronal cells were assayed on substrate-coated fusion proteins. Interestingly, both immunoglobulin (Ig)-like domains 2 and 6 (Ig2, Ig6) promoted neurite outgrowth from dorsal root ganglion cells, whereas neural retinal cells responded only to Ig2. L1 Ig2 contains a previously identified homophilic binding site, whereas L1 Ig6 contains an Arg-Gly-Asp (RGD) sequence. The neuritogenic activity of Ig6 was abrogated by mutations in the RGD site. The addition of RGD-containing peptides also inhibited the promotion of neurite outgrowth from dorsal root ganglion cells by glutathione S-transferase-Ig6, implicating the involvement of an integrin. The monoclonal antibody LM609 against alphavbeta3 integrin, but not an anti-beta1 antibody, inhibited the neuritogenic effects of Ig6. These data thus provide the first evidence that the RGD motif in L1 Ig6 is capable of promoting neurite outgrowth via interaction with the alphavbeta3 integrin on neuronal cells.

Amino Acid Sequence↗
PubMed1998

The potential mechanism of induction of inducible nitric oxide synthase mRNA in alveolar macrophages by lipopolysaccharide and its suppression by ethanol, in vivo.

This study reviews the putative mechanism of ethanol (ETOH)-mediated downregulation of inducible nitric oxide synthase (iNOS) messenger RNA (mRNA) and protein and upregulation of constitutive NOS activity (ecNOS) in immunocompetent cells and endothelium, in vivo. Current evidence supports the hypothesis that ETOH inhibits the phospholipase D-tyrosine kinase pathway involved in the phosphorylation and activation of NADPH oxidase and myeloperoxidase, which upregulates the formation of reactive oxygen intermediates and mitogen-activated protein kinase cascade, including the extracellular receptor-linked kinase 1 and 2 (erk1 and erk2). This decreases reactive oxygen intermediate formation, tyrosine kinase-induced phosphorylation, and activation of transcription factors that, in turn, decreases the expression of iNOS mRNA. Also, ETOH-mediated attenuation of endotoxin-induced downregulation of nuclear protein kinase C activity appears to decrease the stability of expressed iNOS mRNA. ETOH-mediated inhibition of tyrosine kinase activity may also explain the ability of ETOH to upregulate ecNOS enzymatic activity, because tyrosine kinase activity suppresses ecNOS enzymatic activity.

Animals↗
PubMed1998

Subcellular localization and duration of mu-calpain and m-calpain activity after traumatic brain injury in the rat: a casein zymography study.

Casein zymographic assays were performed to identify changes in mu-calpain and m-calpain activity in naive, sham-injured, and injured rat cortex at 15 minutes, 3 hours, 6 hours, and 24 hours after unilateral cortical impact brain injury. Cortical samples ipsilateral and contralateral to the site of injury were separated into cytosolic and total membrane fractions. Marked increases in mu-calpain activity in cytosolic fractions in the ipsilateral cortex occurred as early as 15 minutes, became maximal at 6 hours, and decreased at 24 hours to levels observed at 15 minutes after injury. A similar temporal profile of cytosolic mu-calpain activity in the contralateral cortex was observed, although the increases in the contralateral cortex were substantially lower than those in the ipsilateral cortex. Differences were also noted between cytosolic and total membrane fractions. The detection of a shift in mu-calpain activity to the total membrane fraction first occurred at 3 hours after traumatic brain injury and became maximal at 24 hours after traumatic brain injury. This shift in mu-calpain activity between the two fractions could be due to the redistribution of mu-calpain from the cytosol to the membrane. m-Calpain activity was detected only in cytosolic fractions. m-Calpain activity in cytosolic fractions did not differ significantly between ipsilateral and contralateral cortices, and increased in both cortices from 15 minutes to 6 hours after injury. Relative magnitudes of m-calpain versus mu-calpain activity in cytosolic fractions differed at different time points after injury. These studies suggest that traumatic brain injury can activate both calpain isoforms and that calpain activity is not restricted to sites of focal contusion and cell death at the site of impact injury but may represent a more global response to injury.

Animals↗
PubMed1998

Clinical research on the therapeutic effect of the electro-acupuncture treatment in patients with depression.

Electroacupuncture (EA) stimulation has been found to influence the brain (norepinephrine metabolism in experimental animals). Preliminary clinical research has shown that EA treatment is as effective as amitriptyline for patients with depression. In this study, two consecutive clinical studies on the treatment of depression with EA are conducted. The first study was double blind placebo controlled, in which 29 depressed inpatients were recruited. Patients were randomly divided into three groups: EA + placebo; amitriptyline; and EA + amitriptyline. They received EA and/or amitriptyline treatment for 6 weeks. The Hamilton Rating Scale for Depression, Clinical Global Impression and ASBERG scales for the side effect of antidepressants were used to evaluate the therapeutic efficacy and side effects. Based on the results and research protocol of the first study, a multi-centered collaborative study was conducted, in which 241 inpatients with depression were recruited. Patients were randomly divided into two treatment groups: the EA + placebo and the amitriptyline groups. The results from both studies showed that the therapeutic efficacy of EA was equal to that of amitriptyline for depressive disorders (P > 0.05). Electro-acupuncture had a better therapeutic effect for anxiety somatization and cognitive process disturbance of depressed patients than amitriptyline (P < 0.05). Moreover, the side effects of EA were much less than that of amitriptyline (P < 0.001). The article suggested that EA treatment was an effective therapeutic method for depressive disorders. Particularly, it was a treatment of choice for depressed patients who were unable to comply with the classic tricyclic antidepressants because of their anticholinergic side effects. The possible mechanism of EA treatment is discussed.

Adult↗
PubMed1998

Fluoroquinolone action against mycobacteria: effects of C-8 substituents on growth, survival, and resistance.

Fluoroquinolones trap gyrase on DNA as bacteriostatic complexes from which lethal DNA breaks are released. Substituents at the C-8 position increase activities of N-1-cyclopropyl fluoroquinolones against several bacterial species. In the present study, a C-8-methoxyl group improved bacteriostatic action against gyrA (gyrase-resistant) strains of Mycobacterium tuberculosis and M. bovis BCG. It also enhanced lethal action against gyrase mutants of M. bovis BCG. When cultures of M. smegmatis, M. bovis BCG, and M. tuberculosis were challenged with a C-8-methoxyl fluoroquinolone, no resistant mutant was recovered under conditions in which more than 1, 000 mutants were obtained with a C-8-H control. A C-8-bromo substituent also increased bacteriostatic and lethal activities against a gyrA mutant of M. bovis BCG. When lethal activity was normalized to bacteriostatic activity, the C-8-methoxyl compound was more bactericidal than its C-8-H control, while the C-8-bromo fluoroquinolone was not. The C-8-methoxyl compound was also found to be more effective than the C-8-bromo fluoroquinolone at reducing selection of resistant mutants when each was compared to a C-8-H control over a broad concentration range. These data indicate that a C-8-methoxyl substituent, which facilitates attack of first-step gyrase mutants, may help make fluoroquinolones effective antituberculosis agents.

Anti-Infective Agents↗
PubMed1998

Killing of Staphylococcus aureus by C-8-methoxy fluoroquinolones.

C-8-methoxy fluoroquinolones were more lethal than C-8-bromine, C-8-ethoxy, and C-8-H derivatives for Staphylococcus aureus, especially when topoisomerase IV was resistant. The methoxy group also increased lethality against wild-type cells when protein synthesis was inhibited. These properties encourage refinement of C-8-methoxy fluoroquinolones to kill staphylococci.

Anti-Bacterial Agents↗