PubMed Health⌕ Search

Biomedical subjects

F Qi

Publications and source records attributed to F Qi.

At least 37 records · Page 2Linked to original sources
PubMed2001

The group I strain of Streptococcus mutans, UA140, produces both the lantibiotic mutacin I and a nonlantibiotic bacteriocin, mutacin IV.

Strains of Streptococcus mutans produce at least three mutacins, I, II, and III. Mutacin II is a member of subgroup AII in the lantibiotic family of bacteriocins, and mutacins I and III belong to subgroup AI in the lantibiotic family. In this report, we characterize two mutacins produced by UA140, a group I strain of S. mutans. One is identical to the lantibiotic mutacin I produced by strain CH43 (F. Qi et al., Appl. Environ. Microbiol. 66:3221-3229, 2000); the other is a nonlantibiotic bacteriocin, which we named mutacin IV. Mutacin IV belongs to the two-peptide, nonlantibiotic family of bacteriocins produced by gram-positive bacteria. Peptide A, encoded by gene nlmA, is 44 amino acids (aa) in size and has a molecular mass of 4,169 Da; peptide B, encoded by nlmB, is 49 aa in size and has a molecular mass of 4,826 Da. Both peptides derive from prepeptides with glycines at positions -2 and -1 relative to the processing site. Production of mutacins I and IV by UA140 appears to be regulated by different mechanisms under different physiological conditions. The significance of producing two mutacins by one strain under different conditions and the implication of this property in terms of the ecology of S. mutans in the oral cavity are discussed.

Actinomycetales↗
PubMed2001

[Breast reconstruction with a TRAM flap].

OBJECTIVE: Breast reconstruction with a transverse rectus abdominis myocutaneous (TRAM) flap was performed to enhance the mental and physical well-being of patients. METHODS: The experience with TRAM breast reconstruction in 42 patients was reviewed. The patient selection, flap design and our operative technique were introduced in detail. RESULTS: TRAM breast reconstruction was performed as immediate reconstruction in 25 patients, as delayed reconstruction in 17 cases. 2 cases had partial skin necrosis in the abdominal donor site. 2 had partial necrosis of the TRAM flap. One patient had abdominal hernia. CONCLUSIONS: The additional vascular anastomosis or double-pedicle TRAM flap with intramuscular dissection was the key points to reduce complications. Due to the difficulty of TRAM flap reconstruction, thorough understanding of the technique and surgical accuracy are necessary for both flap safety and aesthetic pleasing results.

Adult↗
PubMed2000

[Extracorporeal shock wave lithotripsy for renal calculi].

OBJECTIVE: The aim of the study was to determine the effectiveness of extracorporeal shock wave lithotripsy(ESWL) therapy for renal calculi. METHODS: 126 patients were treated with Shanghai HX-902 lithotriptor on an inpatient basis. The stone size varied from 0.5 to 2.5 cm. Some patients had a double-J stent inserted prior to treatment. RESULTS: The overall stone-free rate in 2 months was 45.6%, whereas it was 53.3%, 40.8% and 18.1% according to the stone size, < or = 0.8, 0.9-1.9 and > or = 2 cm, respectively. Complications were rare, including 1 subcapsular hematoma formation, 15 renal colics and 5 stone streets, which were managed by conservative treatment or ureteral stenting or additional ESWL and resulted in complete stone clearance. CONCLUSION: ESWL therapy is a reasonable and effective method for renal stone, percutaneous nephrolithotripsy(PCNL) or open surgery should be considered for stones larger than 2 cm.

Adult↗
PubMed2000

Effect of earth's orbital chirality on elementary particles and unification of chiral asymmetries in life on different levels.

Life is chirally asymmetric at all scales from microscopic elementary particles to molecular and macroscopic levels. How these chiral asymmetries in life on different levels are unified remains unanswered. It has been demonstrated that both the biomolecular homochirality and biological rhythms can be caused by the right-handed helical force-field of the Earth's orbital chirality (EOC). Similar to the helical biomolecules (1), it is here suggested that the right-handed EOC force-field could make the right-handed elementary particles more stable than their left-handed enantiomers to result in the symmetry violation of elementary particles, and the EOC could also cause the macroscopic predominant selection of right-handed asymmetries of living objects (e.g. the helical seashells and plants). Our studies indicated that the weak force in weak interaction may only be a form of the EOC force-field at the microscopic particle level, and the chiral asymmetries in life on various levels could be unified by the natural right-handed EOC force-field. Moreover, the chiral and quantum effects, time, mass, rhythms and relativity could also be unified by the interaction of the EOC force-field with chiral motions and structures under certain conditions.

Circadian Rhythm↗
PubMed2000

Periodicity of Earth's orbital chirality and possible mechanism of biological rhythms.

Biological rhythms are ubiquitous in living systems from prokaryote to eukaryote on the Earth. So far, the origin of biological rhythms is still a problem. It is suggested here that the periodicity of the Earth's orbital chirality (EOC) could give rise to the periodicity of the chiral helical biomolecular stability and activity, and then generate the biological rhythms in terrestrial living systems. Our experimental results strongly support the theory that the periodic chiral helical EOC force-field should be the power behind the origin of biological rhythms.

Earth, Planet↗
PubMed2000

Purification and biochemical characterization of mutacin I from the group I strain of Streptococcus mutans, CH43, and genetic analysis of mutacin I biosynthesis genes.

Previously, we reported isolation and characterization of mutacin III and genetic analysis of mutacin III biosynthesis genes from the group III strain of Streptococcus mutans, UA787 (F. Qi, P. Chen, and P. W. Caufield, Appl. Environ. Microbiol. 65:3880-3887, 1999). During the same process of isolating the mutacin III structural gene, we also cloned the structural gene for mutacin I. In this report, we present purification and biochemical characterization of mutacin I from the group I strain CH43 and compare mutacin I and mutacin III biosynthesis genes. The mutacin I biosynthesis gene locus consists of 14 genes in the order mutR, -A, -A', -B, -C, -D, -P, -T, -F, -E, -G, orfX, orfY, orfZ. mutA is the structural gene for mutacin I, while mutA' is not required for mutacin I activity. DNA and protein sequence analysis revealed that mutacins I and III are homologous to each other, possibly arising from a common ancestor. The mature mutacin I is 24 amino acids in size and has a molecular mass of 2, 364 Da. Ethanethiol modification and peptide sequencing of mutacin I revealed that it contains six dehydrated serines, four of which are probably involved with thioether bridge formation. Comparison of the primary sequence of mutacin I with that of mutacin III and epidermin suggests that mutacin I likely has the same bridging pattern as epidermin.

Amino Acid Sequence↗
PubMed2000

Expression of functional delta opioid receptors in vascular smooth muscle.

We evaluated smooth muscle from human internal mammary artery and rat aorta for the presence of delta opioid receptors. Radioligand receptor competition studies using the delta-receptor selective agonist, [3H]-[D-Ala2, Met5] enkephalinamide (DAMA) suggested the expression of a high affinity binding site in rat and human blood vessels that was consistent with the delta-2 opioid receptor subtype. Using RT-PCR with primers to the cloned delta opioid receptor (DOR), a cDNA fragment identical to the known DOR sequence was obtained from the smooth muscle cell line, A-10. Stimulation of A-10 cells with DAMA resulted in a significant mobilization of intracellular calcium and membrane depolarization. Exposure of aortic rings denuded of endothelium to DAMA induced a naltrindole-senstive increase in contractile tone. These data demonstrate the presence of a functional DOR in vascular smooth muscle and a direct impact of opioids on vascular contractile tone.

Animals↗
PubMed2000

Flow cytometric DNA analyses of epithelial dysplasia of the esophagus.

OBJECTIVE: To investigate, with flow cytometry, DNA aneuploidy as a marker of early carcinogenesis in dysplastic esophageal lesions. STUDY DESIGN: DNA content of exfoliated cells from 789 cases of esophageal dysplasia (including mild dysplasia, 195 cases; moderate dysplasia, 383 cases; and severe dysplasia, 211 cases) was determined with a FACS 420 flow cytometer. RESULTS: Cellular DNA content was closely related to the severity of dysplasia. The carcinogenesis rate in patients with dysplasia showed that DNA aneuploidy was significantly higher than in patients showing DNA diploidy. CONCLUSION: DNA aneuploidy in dysplastic lesions is a very important early signal of carcinogenesis. Patients with dysplastic lesions showing DNA aneuploidy should be treated and closely followed.

Aneuploidy↗
PubMed2000

[An epidemiology study on limb injuries in infants aged 0 - 14 years old in Tengzhou area during 1994 - 1998].

OBJECTIVE: To find out epidemiological features on limb injuries in infants. METHODS: Stratified random sampling was carried out to investigate limb injuries in children aged 0 - 14 years old in four villages and townships, Tengzhou city Shandong province from 1994 to 1998. RESULTS: Results showed that the total rate of limb injuried was 2.96% with a ratio of male/female 3.20:1. The injury on arms was higher than on legs. The first three leading rates of injuries were falling, hurt by sharp stuff and traffic accidents. The highest rate of injury took place from May to October during the year. The rate of limb injuried seemed to be increasing with a disabled rate of 115.97/100,000. CONCLUSION: Measures should be taken to reduce the rate of injuries, according to the epidemiological findings.

Accident Prevention↗
PubMed2000

Arm elevation enhances muscle sympathetic nerve activity during static exercise.

The purpose of the present study was to evaluate the effect of hypoperfusion to the static-exercised-muscle induced by arm elevation on muscle sympathetic nerve activity (MSNA) recorded from the right tibial nerve (n= 10) by microneurography. Subjects performed static handgrip exercises (SHG) at 30% of maximal voluntary contraction (MVC) for 2 min, followed by 2 min of posthandgrip muscle ischemia (PHGMI) at the heart level (control) and with the arm elevated (50 cm above heart level). Basal heart rate, mean blood pressure and MSNA responses expressed as burst rate (bursts/min) and total MSNA (%) were unaffected by the arm-position. Heart rate response during SHG was not influenced by the arm elevation, while mean blood pressure and MSNA responses were increased by it (P<0.05). MSNA responses were increased during the second minute of the SHG period (P<0.05) and the PHGMI period (P<0.05) in the elevated arm position. In conclusion, arm elevation increased MSNA responses to SHG and PHGMI, suggesting an increased magnitude of muscle metaboreflex.

Adrenergic Fibers↗
PubMed1999

Preferential impairment of nitric oxide-mediated endothelium-dependent relaxation in human cervical arteries after irradiation.

BACKGROUND: Vascular abnormalities are a major cause of postoperative complications in irradiated tissues. Endothelial cell dysfunction characterized by diminished endothelium-dependent relaxation may be involved. We examined the endothelium-dependent relaxation and morphology of the endothelium in irradiated human cervical arteries. METHODS AND RESULTS: Irradiated arteries were taken from the neck region of patients who had radiation therapy. Arteries from patients who did not receive radiation therapy were used as controls. Endothelium-dependent relaxation to acetylcholine and A23187 was impaired in irradiated arteries. Norepinephrine-induced contraction and sodium nitroprusside-induced relaxation were unchanged. In control arteries, N(omega)-nitro-L-arginine and indomethacin each caused a partial inhibition of endothelium-dependent relaxation. In irradiated arteries, the impaired endothelium-dependent relaxation was unaffected by these agents, but it was abolished by high K(+). Acetylcholine produced similar degrees of hyperpolarization in control and irradiated arteries. Immunohistochemical examination for endothelial nitric oxide synthase indicated no expression in the endothelium of irradiated arteries. Electron scanning microscopy showed morphologically intact endothelial cells in irradiated arteries. CONCLUSIONS: In irradiated human cervical arteries, the nitric oxide- and prostacyclin-mediated endothelium-dependent relaxation, but not endothelium-derived hyperpolarizing factor-mediated relaxation, are specifically impaired, without significant morphological damage of the endothelium. The impaired nitric oxide-mediated relaxation was associated with a lack of endothelial nitric oxide synthase expression. Our results suggest the importance of impaired endothelial function in irradiated human blood vessels, which may partly explain the development of vascular stenosis and poor surgical wound healing in irradiated tissues.

Acetylcholine↗
PubMed1999

Functional analyses of the promoters in the lantibiotic mutacin II biosynthetic locus in Streptococcus mutans.

The lantibiotic bacteriocin mutacin II is produced by the group II Streptococcus mutans. The mutacin II biosynthetic locus consists of seven genes, mutR, -A, -M, -T, -F, -E, and -G, organized as two operons. The mutAMTFEG operon is transcribed from the mutA promoter 55 bp upstream of the translation start codon for MutA, while the mutR promoter is 76 bp upstream of the mutR structural gene. Expression of the mutA promoter is regulated by the components of the growth medium, while the mutR promoter activity does not seem to be affected by these conditions. Inactivation of mutR abolishes transcription of the mutA operon but does not affect its own promoter activity. The expressions of both mutA and mutR promoters are independent of the growth stage, while the production of mutacin II is only elevated at the early stationary phase. Taken together, these results suggest that expression of the mutacin operon is regulated by a complex system involving transcriptional and posttranscriptional or posttranslational controls.

Bacteriocins↗
PubMed1999

The specific genes for lantibiotic mutacin II biosynthesis in Streptococcus mutans T8 are clustered and can be transferred en bloc.

Mutacin II is a ribosomally synthesized peptide lantibiotic produced by group II Streptococcus mutans. DNA sequencing has revealed that the mutacin II biosynthetic gene cluster consists of seven specific open reading frames: a regulator (mutR), the prepromutacin structural gene (mutA), a modifying protein (mutM), an ABC transporter (mutT), and an immunity cluster (mutFEG). Transformations of a non-mutacin-producing strain, S. mutans UA159, and a mutacin I-producing strain, S. mutans UA140, with chromosomal DNA from S. mutans T8 with an aphIII marker inserted upstream of the mutacin II structural gene yielded transformants producing mutacin II and mutacins I and II, respectively.

Bacteriocins↗
PubMed1999

Purification of mutacin III from group III Streptococcus mutans UA787 and genetic analyses of mutacin III biosynthesis genes.

Previously, members of our group reported the isolation and characterization of mutacin II from Streptococcus mutans T8 and the genetic analyses of the mutacin II biosynthesis genes (J. Novak, P. W. Caufield, and E. J. Miller, J. Bacteriol. 176:4316-4320, 1994; F. Qi, P. Chen, and P. W. Caufield, Appl. Environ. Microbiol. 65:652-658, 1999; P. Chen, F. Qi, J. Novak, and P. W. Caufield, Appl. Environ. Microbiol. 65:1356-1360, 1999). In this study, we cloned and sequenced the mutacin III biosynthesis gene locus from a group III strain of S. mutans, UA787. DNA sequence analysis revealed eight open reading frames, which we designated mutR, -A, -A', -B, -C, -D, -P, and -T. MutR bears strong homology with MutR of mutacin II, while MutA, -B, -C, -D, -P, and -T are counterparts of proteins in the lantibiotic epidermin group. MutA' has 60% amino acid identity with MutA and therefore appears to be a duplicate of MutA. Insertional inactivation demonstrated that mutA is an essential gene for mutacin III production, while mutA' is not required. Mutacin III was purified to homogeneity by using reverse-phase high-pressure liquid chromatography. N-terminal peptide sequencing of the purified mutacin III determined mutA to be the structural gene for prepromutacin III. The molecular mass of the purified peptide was measured by laser disorption mass spectrophotometry and found to be 2,266.43 Da, consistent with our supposition that mutacin III has posttranslational modifications similar to those of the lantibiotic epidermin.

Amino Acid Sequence↗
PubMed1999

[Cisplatin-induced apoptosis in laryngeal squamous cell carcinoma strain and the influence on cell cycle].

OBJECTIVE: To find more effective chemotherapeutic agents and treatment regimens, we studied the cytotoxicity of cisplatin to human laryngeal squamous cell carcinoma strain Hep2. METHODS: Using flow cytometry, fluorescence microscopy, and DNA agarose gel electrophoresis technique, we investigated in vitro Hep2 cells in different conditions. RESULTS: Hep2 was adherent cells in normal survival condition. Cisplatin affected Hep2 cell growth apparently. Under fluorescence microscope, necrotic cells were red, apoptotic cells were blue with condensed and fragmented nuclei, and normal cells were evenly blue. Adherent cells were 86%-96% viable. But nonadherent cells were 6%-13% viable. Death cells increased with the increase of drug concentration and time elapsing. Death cells were mainly apoptotic cells. The latter appeared to be time- and dose-dependent. DNA "ladder" was observed for nonadherent cells in agarose gel electrophoresis, but adherent cells were not. "Sub-G1" phase peak occurred in flow cytometry. After cisplatin treatment, the volume of adherent cells increased with dose- and time dependence. Cisplatin could cause Hep2 cell cycle to change. At first, G1 phase cell percentage reduced, while S phase increased. With time elapsing, G2/M phase increased. Cells experienced a slow-down in S-phase followed by a G2 block. CONCLUSION: Apoptosis is a major way of Hep2 cell death after cisplatin treatment and appeared to be time- and dose-dependent. In clinical chemotherapy, cisplatin should be used in high concentration. Inducing apoptosis is one of the characteristics of chemotherapeutic agents. Cisplatin should be taken a combination regimen with cell cycle-special agents.

Antineoplastic Agents↗
PubMed1999

[Nontransitional cell tumor of the bladder].

OBJECTIVE: To study the experience in the treatment and diagnosis of the nontransitional cell tumor of the bladder, and to improve the overall survival rate. METHODS: The records were reviewed that 18 patients with nontransitional cell tumor of the bladder treated from Jan. 1990 to Dec. 1997 (5.1% of the 352 bladder tumors in the same period). 16.7% of the patients had benign tumor, 83.3% malignant. Of the latter 73.3% were invasive. The overall rate of palliative treatment, partial or total cystectomy was compared retrospectively. RESULTS: Three patients with benign tumor are alive. The overall survival rate of 14 patients with malignant tumor at 1, 3 and 5 years was 85.7%, 66.7%, and 57.1%. CONCLUSIONS: Most of the patients had haematuria and irritable bladder symptoms. The proper treatment was partial or total cystectomy. The prognosis was apparently related to the tumor stage and therapy method.

Adolescent↗