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Biomedical subjects

C Meng

Publications and source records attributed to C Meng.

At least 19 recordsLinked to original sources
PubMed2001

Combined use of power Doppler and gray-scale sonography: a new technique for the assessment of inflammatory myopathy.

OBJECTIVE: Ultrasonography (US) is a utilitarian approach to the assessment of inflammatory myopathy (IM). Power Doppler sonography (PDS), a newer technique, enables detection of muscle vascularity and inflammation. We describe the combined use of PDS and gray-scale US in patients with IM. METHODS: We studied 37 IM subjects and 6 control subjects. Clinical scores of muscle strength and function were obtained. The maximum score, 31, represented normal function and strength. Ultrasonographic gray-scale and vascularity results were scored 0-4. Nine subjects had serial assessments. RESULTS: Subjects ranged from 16 to 83 years of age and were predominantly female. IM subjects had significantly abnormal lower clinical scores than controls, 23.0 +/- 5.8 vs 29.8 +/- 2.0 (p < 0.001). Mean peak gray-scale score was 2.1 +/- 0.96 compared to 0.5 +/- 0.84 for controls (p = 0.001), indicating atrophy in the IM group. Similar results were found for average gray-scale scores. Peak vascularity scores were higher in IM, 2.7 +/- 0.8 vs 2.2 +/- 0.3 (p = 0.007). Disease of longer duration was significantly associated with more abnormal gray-scale scores and lower creatine phosphokinase (CPK) levels. PDS scores were more abnormal in disease of shorter duration. There was a negative association between functional scores and inflammatory scores on serial assessment. CONCLUSION: Sonography is a valuable tool in the assessment of IM. Gray-scale and PDS findings were significantly different between IM and control subjects. Abnormal gray-scale US scores were associated with disease of longer duration and lower CPK levels. In contrast, increased vascularity on PDS detected disease of shorter duration and varied with the clinical course more than did gray-scale findings.

Adolescent↗
PubMed2001

[Observation on the changes in nasopharyngeal carcinoma patients' olfactory before and after radiotherapy].

OBJECTIVE: Detecting nasopharyngeal carcinoma (NPC) patients' olfactory before and after radiotherapy for investigating the infection of radiotherapy on these patients' olfactory. METHOD: 100 NPC patients' olfactory were detected before the start of radiotherapy and after the termination of therapy in 3, 6, 12, 24 and 36 months. RESULT: Patients' smell acuity decreased sharply 3 months after therapy, but varying degrees of recovery were noted in 6 and 12 months. However their smell acuity became worse in the following time. CONCLUSION: NPC patients' smell acuity can be profoundly affected by radiotherapy. And after radiotherapy, their smell acuity will decrease wave-likely and cannot fully recover.

Adult↗
PubMed2001

[Upconversion luminescent dynamics of HoP5O14 noncrystallite excited by DCM dye laser].

The dynamics processes of 370-580 nm upconversion luminescence of HoP5O14 noncrystalline excited by DCM dye laser is reported in this paper. It is found that both mechanisms of energy transfer upconversion among ions and step-wise multiphoton absorption of single ion are involved in the upconversion luminescence, the upconversion dynamics would change greatly when the frequency of pumping laser has a little variation.

Crystallization↗
PubMed2001

[An effect enhancement mechanism of up-conversion luminescence--up-conversion sensitization].

The research of frequency up-conversion has been developed greatly in recent ten years. In order to achieve its applications, it needs to enhance the up-conversion efficiency further greatly, which is the core problem of up-conversion. Because of the specialty of Yb3+ ion energy level, Yb3+ can greatly enhance up-conversion luminescence of co-doped rare earth ion activator through energy transfer. Meanwhile it may not cause the obvious fluorescence quenching. Thus it is very significance to investigate up-conversion sensitization which Yb3+ ion acts as a sensitizer. It is more important that it is quite urgent to combine up-conversion efficiency and material property to develop up-conversion. This paper reviews the proposing and developing process of up-conversion sensitization. The achievement of up-conversion sensitization field especial the originate fruit in indirect up-conversion sensitization obtained by China are introduce emphatically.

Chemical Phenomena↗
PubMed2001

[Optical parameters of Tm3+ in oxyfluoride glass ceramic].

Optical-absorption spectrum of Tm3+ ions in oxyfluoride glass ceramic was measured, from which the measured oscillator strengths were obtained. The Judd-Ofelt intensity parameters omega t (t = 2, 4, 6) were determined by a best fit of the calculated and measured oscillator strengths, the rms deviation was 3.9 x 10(-7). Some predicted spectroscopic parameters of the excited states, like the spontaneous radiative transition rate, radiative lifetime, branching ratio and integrated emission cross section were given using the intensity parameters. The spectroscopic parameters were comparable with some laser materials, and some of them were better.

Ceramics↗
PubMed2000

Inhibition of IL-2-induced Jak-STAT signaling by glucocorticoids.

Glucocorticoids (GCs) are potent anti-inflammatory agents that block cytokine production. We investigated whether GCs also block cytokine signaling via the Janus kinase (Jak)-signal transducer and activator of transcription (STAT) pathway. Dexamethasone inhibited IL-2-induced DNA binding, tyrosine phosphorylation, and nuclear translocation of Stat5 in primary T cells. Inhibition of Stat5 correlated with inhibition of expression of IL-2-inducible genes and T cell proliferation. The mechanism of inhibition involved suppression of IL-2 receptor and Jak3 expression. Signaling by IL-4, IL-7, and IL-15, which use IL-2 receptor components, also was inhibited, indicating a block in T cell responses similar to that seen in immunodeficient patients lacking the IL-2 receptor gamma chain or Jak3. IL-2 signaling also was blocked in patients after treatment with GCs, suggesting that inhibition of cytokine signaling contributes to the clinical efficacy of these agents. These results identify inhibition of Jak-STAT signaling by IL-2 and related cytokines as a novel mechanism of GC action and suggest that inhibition of both cytokine production and signaling contribute to their therapeutic potency.

Biological Transport↗
PubMed1999

Pregnancy in lupus.

Patients with systemic lupus erythematosus with established disease have poorer pregnancy outcomes than do women with later onset disease. Active renal disease and maternal hypertension are important predictors of fetal loss and premature birth, respectively. Placental pathology in SLE patients is characterized by decidual vasculopathy and infarction, and in APLS patients, infarction can be extensive. Maternal anti-52 kD SSA/Ro by immunoblot continues to be an important risk factor for having a child with heart block. The risk of having a subsequent child with congenital heart block ranges between 12-16%. Childhood morbidity with heart block is high, with 63% eventually requiring pacemakers. In APLS, antiB2GP-I antibodies can have a significant role in the diagnosis, especially when the traditional assays for aCL antibodies and LAC are negative. Some obstetricians have found that IVIG improves the birthrate in aPL positive women who have recurrent spontaneous abortions after IVF.

Female↗
PubMed1998

Spatial and temporal dynamics of DNA replication sites in mammalian cells.

Fluorescence microscopic analysis of newly replicated DNA has revealed discrete granular sites of replication (RS). The average size and number of replication sites from early to mid S-phase suggest that each RS contains numerous replicons clustered together. We are using fluorescence laser scanning confocal microscopy in conjunction with multidimensional image analysis to gain more precise information about RS and their spatial-temporal dynamics. Using a newly improved imaging segmentation program, we report an average of approximately 1,100 RS after a 5-min pulse labeling of 3T3 mouse fibroblast cells in early S-phase. Pulse-chase-pulse double labeling experiments reveal that RS take approximately 45 min to complete replication. Appropriate calculations suggest that each RS contains an average of 1 mbp of DNA or approximately 6 average-sized replicons. Double pulse-double chase experiments demonstrate that the DNA sequences replicated at individual RS are precisely maintained temporally and spatially as the cell progresses through the cell cycle and into subsequent generations. By labeling replicated DNA at the G1/S borders for two consecutive cell generations, we show that the DNA synthesized at early S-phase is replicated at the same time and sites in the next round of replication.

3T3 Cells↗
PubMed1998

Zoledronate prevents the development of absolute osteopenia following ovariectomy in adult rhesus monkeys.

This study assessed effects of the bisphosphonate zoledronate (ZLN) on bone density and biochemical markers of bone turnover in ovariectomized (OVX) adult female rhesus monkeys. Forty monkeys were randomly assigned to one control or four OVX groups. The control and one OVX group received saline, and the other three OVX groups received ZLN (0.5, 2.5, or 12.5 microg/kg) by a single weekly subcutaneous injection for 69 weeks. Bone mass of the total body (TB), lumbar spine (LS), distal and central radius (dual-energy X-ray absorptiometry), and skeletal turnover markers were measured at baseline and at 13, 26, 39, 52, and 69 weeks of treatment. Increased skeletal turnover and decreased bone mass (LS and TB) were demonstrable by 13 weeks post-OVX. Maximal bone loss (7-8%) at these sites occurred by 39 weeks after OVX and persisted for the study duration. Long-term ZLN treatment was well tolerated and prevented increased skeletal turnover and bone loss in a dose-dependent fashion. Progressive turnover suppression was not observed with any ZLN dose. In conclusion, after OVX, adult rhesus monkeys develop persistent increased bone turnover and absolute osteopenia of the LS and TB, making them an outstanding model of skeletal behavior in perimenopausal women. These OVX-related skeletal changes are dose-dependently blocked by ZLN.

Absorptiometry, Photon↗
PubMed1998

[A longitudinal study on deterioration of physical function in people aged over 55 in Beijing].

The objective of this study is to explore the index of physical performance test in detecting physical functional status among elderly people. Physical performance test, recommended by Yale University in EPESE was used in the study. A total number of 1,986 people aged 55 and over in urban and rural area of Beijing was studied in a three-year longitutinal observation. Among 1,986 cases studied in 1992, 168 died between 1992-1994. The mortality rate increased along with the degree of functional disablement, lowest in non-disabled (3.4%), followed by mild ones (5.2%), moderate (10.5%) and highest in severely disabled (18.4%). It is shown that performance test can be used as a tool in observing and detecting risk groups in the progress of functional disability It's an important index describing the decline of health status.

Aged↗
PubMed1998

[Alteration of peritoneal lymphocyte transformation and its interleukin-2 release in patients with infertility and endometriosis].

OBJECTIVE: To study the relationship between alteration of peritoneal lymphocyte transformation activity, its interleukin-2 (IL-2) release and infertility associated with endometriosis. METHODS: Peritoneal fluid was collected from 15 infertile patients with endometriosis (endometriosis group) and 13 normal fertile women (control group). Lymphocyte transformation activity were determined in peritoneal fluid by morphometry. IL-2 contents were determined in peritoneal fluid and supernatants of cultured pelvic lymphocytes by biological method. RESULTS: Lymphocyte transformation activity reinforced (P < 0.001) and IL-2 contents increased in peritoneal fluid and supernatant of cultured pelvic lymphocyte in the endometriosis group than those in the control group (P < 0.01, P < 0.001 respectively). There is significant positive correlation between lymphocyte transformation rate and IL-2 activity of cultured supernatant in endometriosis group (P < 0.001). CONCLUSION: The increase of IL-2 content in the samples of endometriosis may play an important role in infertility with endometriosis.

Adult↗
PubMed1997

Nephropathy in human immunodeficiency virus-1 transgenic mice is due to renal transgene expression.

HIV-associated nephropathy (HIVAN) is a progressive glomerular and tubular disease that is increasingly common in AIDS patients and one of the leading causes of end stage renal disease in African Americans. A major unresolved issue in the pathogenesis of HIVAN is whether the kidney disease is due to renal cell infection or a "bystander" phenomenon mediated by systemically dysregulated cytokines. To address this issue, we have used two different experimental approaches and an HIV-1 transgenic mouse line that develops a progressive renal disease histologically similar to HIVAN in humans. In the murine model, kidney tissue expresses the transgene and in heterozygous adults, renal disease develops shortly thereafter. We demonstrate by terminal deoxynucleotide transferase-mediated dUTP-biotin nick-end labeling assay that similar to the disease in humans, apoptosis of renal tubular epithelial cells is a component of the molecular pathogenesis. To determine whether apoptosis is due to transgene expression or environmental factors, we treated fetal kidney explants (normal and transgenic) with UV light to induce transgene expression. Apoptosis occurred in transgenic but not normal littermates after stimulation of transgene expression. To confirm a direct effect of HIV expression on the production of HIVAN, we transplanted kidneys between normal and transgenic mice. HIVAN developed in transgenic kidneys transplanted into nontransgenic littermates. Normal kidneys remained disease free when transplanted into transgenic littermates. Thus, the renal disease in the murine model is intrinsic to the kidney. Using two different experimental approaches, we demonstrate a direct effect of transgene expression on the development of HIVAN in the mouse. These studies suggest that in humans, a direct effect of HIV-1 expression is likely the essential cause of HIVAN, rather than an indirect effect of cytokine dysregulation.

AIDS-Associated Nephropathy↗
PubMed1997

Engineering factors affecting the granulation of sludge in the UASB reactor.

The influence of inoculum sludge involving different microbial populations, different modes of stream flow and different flow rates in a bioreactor on the granulation of sludge was studied. In the granulation process there were four periods: formation of microbial floccus, formation of subcore, growth of subcore, and maturity of granules. The production of microfloccus could be attributed to acid-forming bacteria. The hydrodynamic momentum transfer caused by moving phases and the hydraulic shear effect are the crucial factors affecting the formation of the subcore. For this a new concept-the lowest limited flow rate-is proposed, i.e., the lowest flow rate to form an expanded sludge bed. A sufficient feed rate (higher than the lowest flow rate), an appropriate sludge load, and an equal distribution of feed, as well as a suitable alkalinity in the medium are the essential factors for the scaling-up and process-control of the UASB reactor.

Anaerobiosis↗
PubMed1995

A localized elevation of cytosolic free calcium is associated with cytokinesis in the zebrafish embryo.

Cytokinesis, a key step in cell division, is known to be precisely regulated both in its timing and location. At present, the regulatory mechanism of cytokinesis is not well understood, although it has been suggested that calcium signaling may play an important role in this process. To test this notion, we introduced a sensitive fluorescent Ca2+ indicator into the zebrafish embryo and used confocal microscopy to measure the spatiotemporal variation of intracellular free Ca2+ concentration ([Ca2+]i) during cell cleavage. It was evident that a localized elevation of [Ca2+]i is closely associated with cytokinesis. First, we found that during cytokinesis, the level of free Ca2+ was elevated locally precisely at the cleavage site. Second, the rise of free Ca2+ was very rapid and occurred just preceding the initiation of furrow contraction. These observations strongly suggest that cytokinesis may be triggered by a calcium signal. In addition, we found that this cytokinesis-associated calcium signal arose mainly from internal stores of Ca2+ rather than from external free Ca2+; it could be blocked by the antagonist of inositol trisphosphate (InsP3) receptors. These findings suggest that the localized elevation of [Ca2+]i is caused by the release of free Ca2+ from the endoplasmic reticulum through the InsP3-regulated calcium channels.

Animals↗
PubMed1994

Analysis of human growth hormone gene 5' sequences in isolated growth hormone deficiency patients.

Human growth hormone (hGH) gene deletion (6.7 to 7.6 kb) is one of the causes of isolated growth hormone deficiency (IGHD), named IGHD IA. IGHD IA, however, only accounts for about 10% of the total IGHD patients. Most IGHD is caused by unknown mechanisms. Here, hGH gene 5' sequences in three IGHD patients without hGH gene deletion were analysed to see if there was any mutation hindering the expression of the hGH gene.

Base Sequence↗
PubMed1994

[A study on the relation between cerebral lesion and cognitive defect in multi-infarct patients].

240 cases of multi-infarct patients with more than two cerebral infarct lesions in CT findings were collected successively from 1991 to 1992. 42.92% of them were shown to have cognitive defect with a series of neuropsychological tests. Correlation of the occurrence of cognitive defect with the CT findings such as the location and extent of focal lesions as well as the presence of cerebral atrophy or subcortical degeneration were carried out. According to the results by multiple regression and factor analysis, the location and extent of the focal infarct lesions were not the primary determining factor for the occurrence of cognitive defect. It is, therefore, suggested that the term of ischemic or vascular dementia be used clinically instead of the so-called multi-infarct dementia.

Adult↗