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Biomedical subjects

L Ma

Publications and source records attributed to L Ma.

At least 109 records · Page 6Linked to original sources
PubMed2001

Extracellular calmodulin stimulates light-independent RbcS-GUS expression in suspension-cultured cells of transgenic tobacco.

The RbcS genes encode the small subunits of rubisco; the expression of these genes is controlled in a light-dependent and independent manner. It has been reported that intracellular calmodulin (CaM) is involved in light-dependent RbcS expression. In this report, the role of extracellular CaM in regulating expression of RbcS in darkness was examined. The time course of expression of RbcS-GUS and that of the secretion of CaM in the suspended transgenic tobacco cells in darkness were very similar. Both showed initial increase followed by decline with maximum CaM secretion preceding maximum GUS expression by 24 h. The concentration of CaM in the culture medium is regulated light independently. Purified CaM alone added to the media enhanced RbcS-GUS expression in darkness. The addition of membrane-impermeable CaM inhibitors, such as anti-CaM antiserum or W7-agarose, repressed the expression of RbcS-GUS in darkness, but this inhibitory effect was completely reversed by adding exogenous purified CaM. These results provide the first evidence that extracellular CaM is involved in the regulation of light-independent RbcS gene expression.

Calmodulin↗
PubMed2001

Organization of junctional proteins in proliferating cat corneal endothelium during wound healing.

PURPOSE: To evaluate for the first time cell junctional protein organization in proliferating corneal endothelial cells during in vivo wound healing. METHODS: A total of 16 cats (32 eyes) were used in this study. A single 3-mm diameter (n = 24) or 1- to 2-mm diameter (n = 8) scrape injury was created in the central corneal endothelium of each eye. Twenty-four, 48, 72 hours or 5 days after scrape injury, eyes were collected for in situ double- or triple-labeling with phalloidin, anti-ZO-1, alpha-catenin, beta-catenin, and MIB-1 (monoclonal antibody to Ki67, a marker for actively cycling cells) and were imaged using confocal laser microscopy. RESULTS: In 3-mm diameter injuries, endothelial cells completely resurfaced the wound 48 to 72 hours after scrape injury; smaller wounds resurfaced by 48 hours. Ki67 staining was negative 24 hours after scrape injury in all cases. Ki67-positive cells were observed in the central region of the wounds after 48 and 72 hours, and mitotic figures and pairs of postmitotic cells were observed. On day 5, Ki67-positive cells were rarely detected, and no mitotic figures were observed. In the wound area, a significant increase in cell area and a reduction in hexagonality were observed in cycling cells after 48 and 72 hours. Normal apical, pericellular staining of f-actin, ZO-1, alpha-catenin, and beta-catenin was partially maintained at all times during wound healing of small and large wounds. Double-labeling confirmed that these proteins were also present along the apical cell border in Ki67-positive cells. CONCLUSIONS: After in vivo scrape injury, proliferation is limited temporally and spatially to spreading endothelial cells within the wound. Cell junctional connections appear to be maintained in actively cycling cells during healing.

Actins↗
PubMed2001

Light control of Arabidopsis development entails coordinated regulation of genome expression and cellular pathways.

An expressed sequence tag-based microarray was used to profile genome expression underlying light control of Arabidopsis development. Qualitatively similar gene expression profiles were observed among seedlings grown in different light qualities, including far-red, red, and blue light, which are mediated primarily by phytochrome A, phytochrome B, and the cryptochromes, respectively. Furthermore, light/dark transitions also triggered similar differential genome expression profiles. Most light treatments also resulted in distinct expression profiles in small fractions of the expressed sequence tags examined. The similarly regulated genes in all light conditions were estimated to account for approximately one-third of the genome, with three-fifths upregulated and two-fifths downregulated by light. Analysis of those light-regulated genes revealed more than 26 cellular pathways that are regulated coordinately by light. Thus, light controls Arabidopsis development through coordinately regulating metabolic and regulatory pathways.

Arabidopsis↗
PubMed2001

A case of Kaposi's sarcoma associated with pemphigoid nodularis.

Pemphigoid nodularis is a rare variant of bullous pemphigoid. Bullous pemphigoid complicated by internal malignancy has been well documented. There have been only a few reported cases of bullous pemphigoid associated with Kaposi's sarcoma. We described a case of pemphigoid nodularis who later developed Kaposi's sarcoma that might be related to immunosupressive therapy, a situation that has not been reported previously.

Aged↗
PubMed2001

Direct and differential interaction of beta-arrestins with the intracellular domains of different opioid receptors.

beta-arrestins have been shown to play important roles in regulation of signaling and desensitization of opioid receptors in many in vivo studies. The current study was carried out to measure the direct interaction of beta-arrestins with two functional intracellular domains, the third intracellular loop (I3L) and the carboxyl terminus (CT), of delta-, mu-, and kappa-opioid receptors (DOR, MOR, and KOR, respectively). Results from the pull-down assay using glutathione S-transferase fusion proteins demonstrated that beta-arrestins (1 and 2) were able to bind to the I3L of DOR and to the CT of DOR and KOR. Surface plasmon resonance measurement gave similar results with typical dissociation equilibrium constant (K(D)) values in the micromolar range. The site-directed mutagenesis experiment further revealed that certain specific serine/threonine residues in these receptor domains play a critical role in their interaction with beta-arrestins. Taken together, our data clearly indicated that beta-arrestins interact differentially with the functional domains of different opioid receptors; this may provide a possible molecular basis for differential regulation of opioid receptors by beta-arrestins.

Amino Acid Sequence↗
PubMed2001

Genetic analysis of multiple loci suggests that mutations in the Pneumocystis carinii f. sp. hominis dihydropteroate synthase gene arose independently in multiple strains.

To determine if mutations in the dihydropteroate synthase (DHPS) gene of Pneumocystis carinii f. sp. hominis arose in a single strain that was subsequently widely disseminated, we examined four genomic regions of 22 P. carinii clinical isolates selected based on the absence or presence of mutations in the DHPS gene. By single-strand conformation polymorphism and DNA sequencing, we found varying genotypes for each of the four regions in isolates with DHPS mutations, suggesting that these mutations occurred independently in multiple strains of P. carinii. This suggests that exposure to sulfa will select for these mutations in diverse strains.

Alleles↗
PubMed2001

Rapid detection of mutations in the human-derived Pneumocystis carinii dihydropteroate synthase gene associated with sulfa resistance.

Recent studies have shown that point mutations in the dihydropteroate synthase (DHPS) gene of human-derived Pneumocystis carinii are related to exposure to sulfa drugs and possibly represent the emergence of sulfa resistance. We developed a simple single-strand conformation polymorphism (SSCP) method to permit rapid detection of these mutations. With plasmid constructs, SSCP was able to detect as little as 10% of a minority population. The SSCP assay was compared to direct sequencing for typing the DHPS gene by examining 37 clinical isolates with known DHPS sequences and 41 clinical isolates with unknown DHPS sequences. The typing results were consistent between these two methods for all isolates except 11 in which mutations were detected by SSCP but not by direct sequencing. Sequencing of individual clones after subcloning confirmed the presence of mutations in a minority population as determined by SSCP. SSCP is a very simple and sensitive method for rapid identification of P. camii DHPS mutations.

Alleles↗
PubMed2001

Cariogenic actinomyces identified with a beta-glucosidase-dependent green color reaction to Gardenia jasminoides extract.

The oral bacteria Actinomyces naeslundii and Actinomyces viscosus are known to contribute to the initiation and progression of human dental caries, especially root caries. We report that both A. naeslundii and A. viscosus react with a component in the Gardenia jasminoides extract to produce a distinct green product. This green color reaction was found to be dependent on the bacterial beta-glucosidase. The reaction is specific for cariogenic actinomyces, and it can detect as few as 10(4) cells of A. naeslundii and A. viscosus per ml.

Actinomyces↗
PubMed2001

Inflammatory mediators in gastrointestinal defense and injury.

Inflammation of the mucosal layer of the gastrointestinal (GI) tract is not only a feature almost always associated with ulceration of those tissues, but it also plays an important role in both the production and healing of the lesions. The mediators that coordinate inflammatory responses also have the capability to alter the resistance of the mucosa to injury induced by noxious substances, while others render the mucosa more susceptible to injury. In this article, we provide a review of the inflammatory mediators that modulate GI mucosal defense. Among the mediators discussed are nitric oxide, the eicosanoids (prostaglandins, leukotrienes, and thromboxanes), neuropeptides, cytokines, and proteinases. Many of these mediators are considered potential therapeutic targets for the treatment of ulcerative diseases of the digestive tract.

Animals↗
PubMed2001

mKlf7, a potential transcriptional regulator of TrkA nerve growth factor receptor expression in sensory and sympathetic neurons.

Development of the nervous system relies on stringent regulation of genes that are crucial to this process. TrkA, the receptor for nerve growth factor (NGF), is tightly regulated during embryonic development and is essential for the survival and differentiation of neural crest-derived sensory and sympathetic neurons. We have previously identified a mouse TrkA enhancer and have characterized several cis regulatory elements that are important for appropriate TrkA expression in vivo. We now report the cloning of a novel gene encoding a Kruppel-like factor from a mouse dorsal root ganglion expression library. This Kruppel-like factor, named mKlf7, binds specifically to an Ikaros core binding element that is crucial for in vivo TrkA enhancer function. Using in situ hybridization, we demonstrate that mKlf7 is coexpressed with TrkA in sensory and sympathetic neurons during embryogenesis and in adulthood. These data are consistent with the idea that mKlf7 may directly regulate TrkA gene expression in the peripheral nervous system.

Amino Acid Sequence↗
PubMed2001

Radiation necrosis following gamma knife surgery: a case-controlled comparison of treatment parameters and long-term clinical follow up.

OBJECT: Radiation necrosis is the only significant complication of gamma knife surgery (GKS). The authors studied treatment plan parameters in patients who had radiation necrosis to determine if risk factors for necrosis could be identified. METHODS: Between September 1994 and December 1998, 286 patients were treated with GKS by the senior author. Of the 243 patients who were suitable for analysis, 17 developed radiation necrosis and were prospectively followed. Concurrently, 17 patients without necrosis were randomly selected as case controls on the basis of histological findings in their lesions. Integral dose-volume histograms (DVHs) were calculated and dose-volume treatment parameters were determined. A comparison was made with both the established Kjellberg and Flickinger isonecrosis risk lines. Clinical outcome was assessed according to time to resolution of symptoms and return to normal radiographic appearance. CONCLUSIONS: Treatment plan variables associated with the risk of necrosis were increased tumor volume (TV) integral dose, increased TV, and increased 10-Gy volume. Other risk factors included repeated radiosurgery to the same lesion and glioma histological findings. The Kjellberg 1% risk line predicted a 5% risk of radiation necrosis and the Flickinger 3% risk line predicted a 3% risk. The median time to development of necrosis was 4 months, and symptomatic and radiographic recovery times were 7.5 and 10.5 months, respectively. The median survival time in patients with necrosis was 30 months. The authors recommend prospective TV determination and DVH calculation for all radiosurgical treatments and the avoidance of repeated radiosurgical treatments to the same lesion when possible.

Adolescent↗
PubMed2001

The clinical features and surgical results of malignant eyelid tumors.

BACKGROUND: To determine the clinical characteristics and surgical results of patients with malignant eyelid tumors. METHODS: A retrospective study was used to review patients who had malignant eyelid tumors and underwent surgery at our hospital from 1984 to 1999. The therapies for these tumors were surgical excision with immediate peripheral tissue examination of frozen section and Mohs' micrographic surgery. RESULTS: We reviewed 77 patients with malignant eyelid tumors. Their ages ranged from 17 to 98 years with mean age of 63.4 years. The three most common tumors, in order of frequency, were basal cell carcinoma (45 cases, 58.4%), sebaceous adenocarcinoma (14 cases, 18.2%), and squamous cell carcinoma (13 cases, 16.9%). Tumor developed most commonly on the lower eyelid. Six (7.8%) patients had local recurrence after an average period of 3 years and 9 months. Meanwhile, regional metastases were found in 7 patients (9.1%) and distant metastases were found in 4 patients (5.2%). CONCLUSION: In our study, wide excision with frozen section control for malignant eyelid tumor was a relatively useful method. Cosmetically and functionally acceptable results can be achieved after eyelid reconstructive surgery.

Adenocarcinoma↗
PubMed2001

[The quantitative analysis of voice disease based on fractal method].

The fractal method is employed to check the voice diseases. The severity of pathological changes of human voice can be analyzed objectively and quantitatively with different fractal dimensions. With this method we can end up the history of judging the voice with subjective hearing and it is of great importance to the development of laryngology.

Fractals↗
PubMed2001

Cholecystectomy prevents expansion of the bile acid pool and inhibition of cholesterol 7alpha-hydroxylase in rabbits fed cholesterol.

To study the effect of cholecystectomy on the regulation of classic and alternative bile acid syntheses, gallbladder-intact (n = 20) and cholecystectomized (n = 20) New Zealand White rabbits were fed either chow or chow with 2% cholesterol (3 g/day). After 10 days, bile fistulas were constructed in half of each rabbit group to recover and measure the bile acid pool and biliary bile acid flux. After cholesterol feeding, the bile acid pool size increased from 268 +/- 55 to 444 +/- 77 mg (P < 0.01) with a 2-fold rise in the biliary bile acid flux in intact rabbits but did not expand the bile acid pool (270 +/- 77 vs. 276 +/- 62 mg), nor did the biliary bile acid flux increase in cholecystectomized rabbits. Ileal apical sodium-dependent bile acid transporter protein increased 46% from 93 +/- 6 to 136 +/- 23 units/mg (P < 0.01) in the intact rabbits but did not change in cholecystectomized rabbits (104 +/- 14 vs. 99 +/- 19 units/mg) after cholesterol feeding. Cholesterol 7alpha-hydroxylase activity was inhibited 59% (P < 0.001) while cholesterol 27-hydroxylase activity rose 83% (P < 0.05) after cholesterol feeding in the intact rabbits but neither enzyme activity changed significantly in cholesterol-fed cholecystectomized rabbits. Fecal bile acid outputs reflecting bile acid synthesis increased significantly in the intact but not in the cholecystectomized rabbits fed cholesterol. Removal of the gallbladder prevented expansion of the bile acid pool after cholesterol feeding as seen in intact rabbits because ileal bile acid transport did not increase. As a result, cholesterol 7alpha-hydroxylase was not inhibited.

Animals↗
PubMed2001

[Influence of fluid shear stress on the expression of monocyte chemotactic protein-1 by vascular endothelial cells].

OBJECTIVE: To study the effect of fluid shear stress on the expression of monocyte chemotactic protein-1(MCP-1) by vascular endothelial cells and its role in the early stages of atherogenesis(AS). METHODS: Parallel plate flow chamber was used to expose vascular endothelial cells to different shear stress. Sandwich ELISA (enzyme-linked immunosorbent assay) and RT-PCR (reverse transcription polymerase chain reaction) were applied to detect MCP-1 protein and mRNA respectively. RESULTS: Under 0.72 Pa shear stress, MCP-1 mRNA expression in endothelial cells reached a high level in 5 hours, but decreased to below the control level (P < 0.001) after 12 hours. The expression of MCP-1 mRNA showed a time dependent increase, which became slower 5 hours later. When different shear stress (0.30, 0.72, 2.40 Pa) was loaded for the same period of time (5 h), MCP-1 increased to above twice the control level, while its mRNA expression increased threefold as compared to the static control. CONCLUSIONS: The expression of MCP-1 reacts strongly to fluid shear stress. The steady laminar flow down regulates the gene expression of MCP-1. These results may help to explain why AS lesions tends to occur at the site of turbulent blood flow.

Cells, Cultured↗
PubMed2001

[Study of pefloxacin concentration in blood and sputum in the aged pneumonia patients with impairment of renal function].

OBJECTIVE: To study the drug concentration in blood and sputum, clinical effect and drug toxicity of pefloxacin in the aged pneumonia patients with different degree of impairment of renal function. METHODS: The patients were divided into four groups according to the impairment of renal functions pefloxacin 400 mg/12 h venous inflow, period of treatment is 10 days. Clinical manifestation and experimental index were registered; the drug concentration in blood and sputum was measured with biochemical technique, then compared and analyzed. RESULTS: The drug concentration in blood and sputum in four groups differed from the degree of the impairment of renal function. The concentration of drug in blood and sputum of the normal renal function was close to that in the low-grade impairment of renal function. Their clinical effective ratios were 83%, 80%, bacterium cleanup ratio was 86%. The difference of drug concentration in blood and sputum in the severe impairment of renal function was greater than that in the moderate renal function group, their clinical effective ratios were 66%, 53%, bacterial cleanup ratios were 57%, 36%, adverse reaction was growing along with degree of impairment of renal function. This drug has renal toxicity for moderate and severe impairment of renal function. CONCLUSION: In case of moderate impairment of renal function, prolongation of dose interval should be considered; pefloxacin should be avoided in severe impairment of renal function.

Aged↗