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Biomedical subjects

C Ling

Publications and source records attributed to C Ling.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Effect of Sisheng Decoction on repairing function of DNA in mice splenic lymphocytes].

OBJECTIVE: To explore the mechanism of alleviating the side effects of irradiation by Sisheng Decoction (SSD). METHODS: The mice splenic lymphocytes were treated by hydroxylurea to stop the DNA replication in S stage, irradiated by ultraviolet ray (UV) and the 3H TdR was added into the cultural medium. After the lymphocytes were cultured in 37 degrees C for 4 h, the capacity for 3H-TdR in the lymphocytes were tested. The effect of SSD in different content on the cut and patch repair(CPR) of DNA can be inferred by observing the lymphocyte uptake index (LUI) of 3H-TdR. RESULTS: LUI of mice spleen lymphocytes could be increased by pretreating the lymphocytes with SSD for 4 h and then irradiated by UV, but it could not be increased if the lymphocytes were treated by SSD and UV at the same time. CONCLUSION: SSD can alleviate the side effect of irradiation by enhancing the function of CPR-DNA, which need pretreating the lymphocytes with SSD.

Animals↗
PubMed1997

Target- as well as source-derived factors direct the morphogenesis of anomalous retino-thalamic projections.

Neonatal tectal lesions in hamsters result in the elimination of a major central target of retinal axons, massively denervate the lateral posterior nucleus of the thalamus (LP), and lead to a marked increase of the retino-LP projection. In such animals, retino-LP axons show all of the normally-occurring terminal types. In addition, large clusters of varicosities, whose tubular configuration resembles the major type of tecto-LP terminals observed in normal animals, are also noted if the tectal lesion is made on the day after birth (P1). If, however, the neonatal lesion occurs on P5 rather than on P1, terminals resembling normal tecto-LP endings are rarely observed; rather, the distribution and morphology of retino-LP terminals bear a greater resemblance to those seen in normal hamsters, but the size and complexity of the terminals, particularly those that form string-like arrangements, is significantly increased. Our findings suggest that the altered morphology of some abnormally induced retino-LP terminals may be orchestrated by target-associated signals. However, there are age-related limitations on the degree to which afferent systems can vary their terminal morphology; these restrictions may derive from the target, or may be a function of intrinsic changes within the cells of origin of the afferent fibers.

Animals↗
PubMed1997

Afferents from the colliculus, cortex, and retina have distinct terminal morphologies in the lateral posterior thalamic nucleus.

We have examined the morphology of afferent endings that originate in three distinct cell groups and terminate in the lateral posterior nucleus of the thalamus (LP). Retino-LP projections were sparse, occurred throughout the nucleus, and could be classified into 1) simple en passant varicosities and terminal swellings found on poorly branched fibers in all LP subdivisions, 2) string-like configurations of varicosities detected largely in the medial subdivision of the LP, and 3) terminals resembling retinogeniculate endings occurring mainly in the rostral part of the superficial subdivision of the LP adjacent to the dorsal nucleus of the lateral geniculate body. Cortico-LP terminals fell into three classes: 1) single varicosities decorating the tips of short appendages on fine preterminal and terminal axons; 2) tiny, round varicosities studding the axon shaft; and 3) boutons of variable shape visible on medium-caliber corticothalamic fibers. Tecto-LP terminals exhibited a large variation in morphology and density. Those found most commonly could be classified into two groups: 1) individual swellings and 2) terminal clusters arranged in a tubular configuration that enclosed a central channel, most likely occupied by the dendrite of a postsynaptic neuron. An unusual tecto-LP terminal consisted of an ovoid swelling (up to 20 microns in the long axis) from which emerged several long, thin extensions and was seen at the tips of large-diameter axons. These results show that, despite having overlapping projection zones, each set of afferents that projects to the LP elaborates terminal specializations that are structurally distinct from others projecting to the same target area.

Afferent Pathways↗
PubMed1997

A dominant negative mutation in Saccharomyces cerevisiae methionine aminopeptidase-1 affects catalysis and interferes with the function of methionine aminopeptidase-2.

Methionine aminopeptidase (MetAP) enzymes require the metal ion cobalt, but little is known about the role of cobalt in the structural stability or catalysis of these enzymes. In Escherichia coli MetAP, for which a crystal structure is available, the five amino acid residues liganding the two cobalt ions are Asp97, Asp108, His171, Glu204, and Glu235. These five amino acids are conserved in all MetAPs sequenced to date. The C-terminal domain of the yeast Saccharomyces cerevisiae MetAP1 is 41% identical to E. coli MetAP and contains these cobalt coordinating residues. Using site-directed mutagenesis on the gene coding for yeast MetAP1, we replaced Asp219 (corresponding to Asp97 in E. coli MetAP) with Asn. The yeast D219N mutant enzyme has 10(3)-fold lower catalytic activity and a different substrate specificity when compared to wild-type yeast MetAP1. These results indicate that the side-chain of Asp219 is important for catalysis. Expression of D219N-MetAP1 in yeast causes a slow-growth phenotype and interferes with wild-type MetAP1 in a dominant manner. Expression of D219N-MetAP1 also affects the function of S. cerevisiae MetAP2.

Aminopeptidases↗
PubMed1997

Neurogenesis in juvenile and adult ring doves.

Studies in songbirds suggest that neurogenesis during the first few years of life is related to song learning. In this study, we examined whether postnatal neurogenesis occurs in a nonsongbird, the ring dove (Streptoplia risoria), and whether it persists to old age. Twenty-four hours after a single intramuscular injection of [3H]thymidine, labeled cells were present in the brains, particularly in the lateral wall of the lateral ventricle of juvenile (3-month and 8-month) and adult (1-year to 8-year) doves. Two months after multiple [3H]thymidine injections, there were fewer labeled cells in the ventricular zone (VZ), but many labeled cells with neuronal morphology in the parenchyma of the forebrain; labeled cells were confirmed as neurons by using neuron-specific markers, microtubule-associated protein-2 (MAP-2) and anti-neuronal nucleus (NeuN). In general, new neurons were distributed in the forebrain without clustering in any particular nucleus. During the first year of life, however, neostriatum caudale and hyperstriatum, the regions known to be essential for proper integration of sensory cues and reproductive behavior, contained more new neurons than any other brain regions. These neuronal additions showed an age-related decline; the first reduction coincided with the dove's attainment of adult physical size (about 3 months old) and the second occurred when the dove would normally attain reproductive fitness (about 1 year old). A low level of forebrain neurogenesis persisted up to 8 years of age (the oldest animals studied). These observations suggest that neurogenesis in adulthood is widespread among birds but that the biological significance of adult neurogenesis in the ring dove remains to be determined.

Aging↗
PubMed1997

Currycombs for the vaginal paravaginal defect repair.

BACKGROUND: The paravaginal defect, present in more than three-quarters of patients with cystoceles, can be repaired by both the abdominal and vaginal approaches. The technical challenges of the vaginal paravaginal repair have militated against its widespread adoption by gynecologic surgeons. INSTRUMENT: Currycombs can be used to facilitate suture management during vaginal paravaginal repair. EXPERIENCE: The vaginal paravaginal repair using currycombs was performed as part of pelvic repair surgery on 27 patients. Perioperative complications were minimal. A cystocele cure rate of 80% was achieved after a mean follow-up of 8 months. CONCLUSION: The use of currycombs during performance of the vaginal paravaginal repair facilitates suture management. The addition of this technique should help gynecologic surgeons to perform this somewhat daunting surgical procedure.

Female↗
PubMed1997

Assessment of Physics Quality Assurance in United States Radiotherapy Facilities and Comparison With American College of Radiology Standard for Radiation Oncology Physics for External Beam Therapy.

We have assessed radiation therapy physics quality assurance (QA) elements in the United States and compared the results with the Patterns of Care Study (PCS) Consensus Guidelines for Treatment Planning and the American College of Radiology (ACR) Standard for Radiation Oncology Physics for External Beam Therapy. Data were obtained during PCS site visits to 73 facilities randomly selected from the 1,321 radiation therapy facilities in the United States: 21 academic, 26 hospital, and 26 freestanding. The following is a representative sample of results. The estimated national averages for facilities having QA programs for treatment planning systems, simulators, accelerators, film processors, and blocking systems are 44%, 79%, 94%, 62%, and 55%, respectively. Only 63% of facilities obtain an independent check of their accelerator calibrations from a source outside the facilities obtain an independent check of their accelerator calibrations from a source outside the facility. Twenty-six percent of facilities surveyed did not have in vivo dosimetry capability. These results and others in the study were compared with PCS consensus guidelines and ACR standards, This is the first such study performed in the United States, and the results establish a baseline for future studies. A recommendation for a comprehensive national physics QA study is based on deficiencies found in this study and the implementation of new technologies in radiation therapy.

Journal Article↗
PubMed1995

Treatment planning structure and process in the United States: a "Patterns of Care" study.

PURPOSE: To conduct a study of the structure and process of treatment planning in the United States. METHODS AND MATERIALS: A Patterns of Care treatment planning consensus committee developed a survey form that was used to gather data for 106 items relating to the structure and process of treatment planning. These questions were general in nature and not specific to any particular disease site. Seventy-three facilities were randomly selected for site visits from the 1321 radiation therapy facilities in the United States: 21 academic, 26 hospital, and 26 free-standing. During the site visit the facility physicist, assisted by the site-visit physicist, completed the form. RESULTS: Twenty-nine percent of facilities have cobalt-60 machines; 25% have 4 MV linacs; 75% have photon energies in the range of 5-8 MV; and less than 10% have energies greater than 20 MV. Academic facilities led hospital and free-standing facilities by about 30 percentage points in the availability of all electron energies (88 vs. 58%, approximately, in the range 4-13 MeV and scaling downward to about 60 vs. 30% at the highest energies). The national averages for the availability of Cs-137, Ir-192, and I-125 were 87, 73, and 44%, respectively. Computerized tomography (CT) scanning is not available or not used in 15% of hospital and free-standing facilities. Ninety-six percent of facilities have treatment planning computers; at 10% of facilities physicians do not participate in treatment planning. The estimated national averages of facilities having formal quality assurance (QA) programs for treatment planning systems, simulators, film processors, and blocking systems are 44, 79, 62, and 55%, respectively. Sixty-three percent of facilities obtain independent machine calibrations. CONCLUSION: This is the first patterns of treatment planning study carried out in the United States and the results reported here will establish a baseline for future studies. The present study has identified some elements that were unexpected, such as the percentage of facilities lacking formal QA programs for treatment planning systems; however, it has not established any impact of such findings. It is recommended that future studies include the availability of new technologies such as multileaf collimation, dynamic wedges, digital portal imaging, and CT simulation. With the increasing nationwide concern with the cost of health care, we must continue to monitor the implementation, use, and impact on treatment outcome of new and expensive technologies.

Brachytherapy↗
PubMed1995

Evidence that two zinc fingers in the methionine aminopeptidase from Saccharomyces cerevisiae are important for normal growth.

Limited proteolysis of intact yeast methionine aminopeptidase (MAP1) with trypsin releases a 34 kDa fragment whose NH2-terminal sequence begins at Asp70, immediately following Lys69. These results suggest that yeast MAP may have a two-domain structure consisting of an NH2-terminal zinc finger domain and a C-terminal catalytic domain. To test this, a mutant MAP lacking residues 2-69 was generated, overexpressed, purified and analyzed. Metal ion analyses indicate that 1 mol of wild-type yeast MAP contains 2 mol of zinc ions and at least 1 mol of cobalt ion, whereas 1 mol of the truncated MAP lacking the putative zinc fingers contains only a trace amount of zinc ions but still contains one mole of cobalt ion. These results suggest that the two zinc ions observed in the native yeast MAP are located at the Cys/His rich region and the cobalt ion is located in the catalytic domain. The kcat and Km values of the purified truncated MAP are similar to those of the wild-type MAP when measured with peptide substrates in vitro and it appears to be as active as the wild-type MAP in vivo. However, the truncated MAP is significantly less effective in rescuing the slow growth phenotype of map mutant than the wild-type MAP. These findings suggest that the zinc fingers are essential for normal MAP function in vivo, even though the in vitro enzyme assays indicate that they are not involved in catalysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Fragmentation of therapeutic human immunoglobulin preparations.

Some commercial batches of human therapeutic immunoglobulins (Ig) have been found to show evidence of molecular fragmentation when examined by molecular sizing methodologies including sodium dodecyl sulphate polyacrylamide gel electrophoresis [SDS-PAGE] and size exclusion high performance liquid chromatography (SE-HPLC). These batches all demonstrated impaired immunobiological activity (efficacy) as assessed by Fc function measured using a rubella haemolytic assay and as such are likely to be subpotent for therapeutic use. Fragmented Igs were characterized by the presence of at least three protein bands and peaks additional to monomeric IgG. Incubation of Igs with blood enzymes (plasmin and kallikrein) reproduced the fragmentation patterns observed for intrinsically degraded batches, suggesting that fragmentation occurred by contamination with these proteases from the source material (human blood) during manufacture. Intravenous Igs (IVIG) were found to be more susceptible to proteolysis than intramuscular Igs, probably as a consequence of the post-fractionation processing that some IVIGs receive which may induce molecular alterations, allowing enzyme access and fragmentation. Two of the products examined were found to be relatively resistant to proteolysis and both were formulated by processes that limit enzyme activity. These processes were inclusion of an enzyme inhibitor, alpha 2-macroglobulin, and formulation at acidic pH. Enzyme carry-over into the final product is a likely cause of Ig fragmentation, and reduction in levels of such contamination should lead to improvements in product stability and efficacy.

Chemical Phenomena↗
PubMed1995

[The prospective study of trial labor following previous cesarean section].

OBJECTIVE: To investigate the trial of labor following previous cesarean section. METHODS: Three hundred and sixty one cases of pregnant women with history of previous low segment transverse cesarean section were prospectively studied on mode of delivery. 158 cases delivered by elective repeat cesarean section. 203 cases were allowed a trial of labor. RESULTS: 183 out of 203 patients had successful vaginal deliveries. One patient with uterine scar partly ruptured was noted on uterine exploration after delivery. There was no maternal death. The rate of spontaneous vaginal delivery was 79.2%. The rate of vacuum extractor and low forceps deliveries was 20.8%. The 1 minute Apgar score of 170 newborns was > or = 8. Neonatal asphyxia was found in 13 newborns and there was one neonatal death due to congenital abnormality. CONCLUSIONS: Carefully selecting the indication of trial labor and monitoring the labor course are very important for increasing successful vaginal delivery rate and reducing repeat cesarean section.

Adult↗
PubMed1994

A comparative trial between diclofenac-gentamicin and betamethasone-neomycin drops in patients undergoing cataract extraction.

Eighty patients were randomised in a single-masked parallel-group study to receive topically either the test drug, a diclofenac and gentamicin combination, or a betamethasone and neomycin combination after routine cataract extraction and intraocular lens implantation. Each group was assessed over a 6 week period for post-operative inflammation. The two drug combinations were equally effective in suppressing inflammation in the early post-operative stages and the diclofenac-gentamicin combination was slightly more effective in the later stages. The test drug was well tolerated and showed no adverse effects. We feel it is an effective and relatively safe drug which has a role as an anti-inflammatory agent after cataract extraction and has potential advantages in certain circumstances.

Aged↗
PubMed1994

Comparison of dietary habits, physical activity and body size among Chinese in North America and China.

BACKGROUND: Chinese in North America have higher rates of many chronic diseases than do Chinese in Asia. However, there is a lack of data among comparisons of the environmental and lifestyle factors for Chinese in China and Chinese residing in North America. METHODS: We examined self-reported dietary nutrient intakes, physical activity patterns and body mass index of 2488 healthy Chinese men and women residing in North America (US and Canada) and in the People's Republic of China. RESULTS: On average, Chinese in China consumed more calories (males 2904 kcal in China, versus 2201 kcal in North America; females 2317 Kcal in China, versus 1795 Kcal in North America and more carbohydrate, but less fat (males 72.2 g in China versus 84.5 g in North America, females 56.6 g in China versus 70.8 g in North America), protein, vitamin A, beta-carotene and vitamin C than did Chinese in North America. Per cent calories from fat was 35% for Chinese in North America and 22% for Chinese in China. In contrast, the per cent of calories from carbohydrates was 62-68% in China and 48% in North America. Chinese in China reported spending more time in vigorous activity, sleeping and walking but less hours in sitting than Chinese in North America. Chinese in China weighted less and were leaner than North American Chinese. CONCLUSIONS: These differences in nutrient intakes, physical activity and body size of Chinese living on two different continents suggest possible explanations for observed differences in chronic disease rates in the two populations.

Asian People↗
PubMed1993

Interlocking Crawford triangles in frontalis suspension.

In Crawford's pattern of frontalis suspension, two bands are passed, one nasally and the other temporally, forming two base-down triangles with their apexes attached at the brow incisions. Over time, opposing vector forces in the center of the eyelid can cause "cheese-wiring" of the bands with resultant shortening of the inferior bases of both triangles and loosening of the suspensory loops. We modified the standard pattern by interlocking the bands centrally in the lid. A mathematical model was developed that demonstrates neutralization of these opposing forces, resulting in a symmetrical and flexible redistribution of the lifting forces. In support of this mathematical model, a retrospective analysis of 42 consecutive cases using this technique revealed good aesthetic results in terms of lid height, contour, and symmetry, with no important complications from this modification.

Adolescent↗
PubMed1992

Restriction of serum antibody reactivity to the V3 neutralizing domain of HIV gp120 with progression to AIDS.

OBJECTIVE: To identify epitopes on HIV-1 gp120 that correlate with disease resistance and/or prognostic indication. DESIGN: The identification of epitopes on HIV-1 gp120 was determined by testing the reactivity by immunoblotting of anti-HIV-positive human sera against partially cleaved Chinese hamster ovary (CHO) cell-derived recombinant gp120. Cleavage of recombinant gp120 occurs in the V3 loop region resulting in 70 and 50K cleavage bands if the protein is subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. Antibodies reactive with the 120 Mr band alone on immunoblotting indicate that binding is restricted to this cleavage site. Reactivity to either of the cleavage products is independent of gp120 cleavage and indicates that binding occurs in sites other than the V3 cleavage region. METHODS: A panel of anti-HIV-positive human sera was tested for virus neutralizing activity and reactivity by immunoblotting against CHO cell-derived gp120. RESULTS: All sera reacted with the uncleaved from of gp120 but reacted either weakly or did not react with its cleavage products. There was a statistically significant correlation between serum reactivity to cleavage products and clinical stage of disease [Centers for Disease Control (CDC) criteria]. Sera of asymptomatic individuals (CDC stage II/III) were more likely to recognize either one or both of the cleavage products compared with sera from patients presenting with symptoms of disease (CDC stage IV). Furthermore, sera reacting with either one or both of the cleavage products were more likely to have higher neutralizing antibody titres than those that were unreactive. CONCLUSIONS: There is a restriction of serum antibody reactivity (when tested by immunoblotting) to the V3 loop with progression to disease. Raised neutralizing antibody titres may be dependent on regions outside the V3 cleavage site.

Acquired Immunodeficiency Syndrome↗