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Biomedical subjects

F Yu

Publications and source records attributed to F Yu.

At least 55 records · Page 3Linked to original sources
PubMed2000

Subclinical infection with the nematode Trichostrongylus colubriformis increases gastrointestinal tract leucine metabolism and reduces availability of leucine for other tissues.

Gastrointestinal (GI) tract leucine metabolism was measured in 6- to 9-mo-old lambs subjected to trickle infection with Trichostrongylus colubriformis larvae and in separate animals that were not infected. Animals prepared with a jejunal catheter and with indwelling catheters into the aorta and the portal- (PDV) and mesenteric- (MDV) drained viscera were infused simultaneously with [1-13C] and [5,5,5-2H3] leucine to determine GI tract sequestration of leucine from arterial and luminal amino acid pools by tracer and tracee arteriovenous concentration differences. Leucine oxidative losses and net fluxes were also determined across the GI tract. Infection had no detectable effect on whole-body leucine flux, but it increased total GI tract leucine sequestration by 24% (P<.05) and GI tract oxidative losses of leucine by 22 to 41% (P<.01). Net PDV fluxes of leucine were decreased by 20 to 32% during the infection. The infection did not alter either the proportion of precursor leucine used by GI tract metabolism that was derived from the arterial leucine pool (.84 to .88) or the proportional sequestration of digesta-derived leucine during "first pass" absorptive metabolism (.12 to .18). These findings help to elucidate the metabolic basis for the reduced growth rates and nitrogen retention observed when animals are subjected to subclinical nematode infection.

Animals↗
PubMed2000

Immobilization of antibodies on ultraflat polystyrene surfaces.

BACKGROUND: Functional antibody surfaces were prepared on ultraflat polystyrene surfaces by physical adsorption, and the uniform distribution of monoclonal antibodies against hepatitis B surface antigen (anti-HBs) on such surfaces and the presence of dense hepatitis B surface antigen (HBsAg) particles captured by immobilized antibodies were identified. METHODS: A model polystyrene film was spin-coated directly onto a silicon wafer surface. Atomic force microscopy was used to directly monitor the immobilization of anti-HBs antibodies and their specific molecular interaction with HBsAg. Enzyme immunoassay was also used to characterize functional antibody surfaces. RESULTS: A mean roughness of 2 A for areas of 25 microm(2) was produced. We found a uniform distribution of anti-HBs antibodies on ultraflat polystyrene surfaces and the presence of dense HBsAg particles bound to such anti-HBs surfaces after incubation with HBsAg. CONCLUSIONS: This study confirmed the potential of preparing dense, homogeneous, highly specific, and highly stable antibody surfaces by immobilizing antibodies on polystyrene surfaces with controlled roughness. It is expected that such biofunctional surfaces could be of interest for the development of new solid-phase immunoassay techniques and biosensor techniques.

Adsorption↗
PubMed2000

[Detection of microbes adherent to particles in a closed environment].

OBJECTIVE: In order to provide reference for controlling and monitoring the environmental contamination in the spacecraft, the species and amount of microbes, which adhere to the suspended particles with different size in a closed environment were detected. METHOD: According to USA EPA IP-10, particles were continuously sampled by an impactor in a closed environment. The particles were divided into three grades by their aerodynamic diameters (AD): 100 micrometers > or = AD > 10 micrometers, 10 micrometers > or = AD>2 micrometers and AD < or = 2 micrometers. Clean outdoor air was collected as control by the same way. The collected particles were precisely weighed. The microbes that adhere to the particles were cultivated, counted and identified. RESULT: By calculating total suspended particles (TSP) and inhalant particles (IP) of the closed environment, counting, clarifying and identifying the microbes, 6 kinds of bacteria, 2 genus of actinomyces and 6 kinds of fungi that adhere to the particles were detected. CONCLUSION: The particles in a closed environment may have some effect on human health and instruments.

Actinomyces↗
PubMed2000

[Long-term results of combined therapy for primary osteosarcoma in extremities].

OBJECTIVE: To evaluate the survival rates, functional outcome, and complications between the combined and non-combined treatment of primary osteosarcoma of the extremities. METHOD: From 1977 through 1992, 170 patients with high-graded, nonmetastatic osteosarcoma were treated. Their average age at diagnosis was 21 years old (ranging from 6 to 52). Tumors were observed at distal femurs in 80 patients (47%), proximal tibia in 51 (30%), proximal humors in 10 and other locations in 22. Combined therapy (en bloc resection of tumor with preoperative and postoperative neoadjuvant chemotherapy) was given 104 patients and non-combined therapy (tumor resection only) to 66. Ninety-four patients underwent limb salvage surgery. In 76 patients who received amputations or disarticulations 33 received chemotherapy. RESULTS: The 5-and 10-year-survival rates were 61% and 53% in the combined therapy group and 28% and 26% in the non-combined therapy group. Local recurrence rate was 23% in limb salvage surgery group and 5.2% in amputation group. Functional evaluation of 80 patients showed that the patients who underwent salvage surgery had higher functional scores than those who had an amputation according to MSTS scoring system (1993). The average scores reached 71% in the salvage surgery group and 53% in the amputation group. CONCLUSIONS: In this study, long-term that combined therapy raised the survival rate of the patients with osteosarcoma. The ase of en bloc resection of bone tumor and reconstructive technique, has enable limb salvage procedures possible to produce excellent functional outcomes. The patients who well have responses to preoperative chemotherapy may have a higher survival rate.

Adolescent↗
PubMed2000

[Telangiectatic osteosarcoma: report of 10 cases].

OBJECTIVE: To raise the level of early diagnosis of telangiectatic osteosarcoma (TOS). METHODS: Ten patients with TOS were treated from July 1991 to December 1998. The patients included men 6 and 4 women, aged from 4 to 44 years (average 23.7 years). The lesions were located at the proximal femur (1 patient), distal femur metaphysis (2), femur shaft (1), proximal tibia metaphysis (2), distal tibia (1) and humerus shaft (3). Preoperative pathologic examination showed two cases of TOS by open biopsy(negative by needle biopsy); the rest were found negative (2 patients), metastasis (1), and sarcoma (5) by needle biopsy. Eight patients received preoperative chemotherapy. Operations including limb-salvage (3) and amputation (7) were performed in all patients. All patients accepted postoperative chemotherapy. RESULTS: 10 Follow-up for a mean of 28 months (range 6 - 72 months) showed no local recurrences: disease-free in 4 patients and pulmonary metastasis in, 6, of whom 5 died and 1 is still alive with lung metastasis. CONCLUSION: TOS is often misdiagnosed and needs early diagnosis and correct treatment under the cooperation of clinicians, radiologists and pathologists.

Adolescent↗
PubMed2000

[A study on the shape of nose of the Jingpo people in China].

The objective of this survey was to provide data for clinical plastics of nose, medical aesthetics and cosmetology, anthropology, nationality study and medical jurisprudence. We carried out a somatological survey on the nose of 611 Jingpo people living in Yunnan. The survey covered 277 males (aged 15 to 60 years) and 334 females (aged 13 to 55 years). The findings of the features of nose are as follows: the Nasal Root Height is high (average 55.83%); the Nasal Tip Direction is forward (average 81.17%); the Nasal Base is horizontal (average 79.17%); the Alae Nasi is slightly projecting (average 91.83%); the Nasal Profile is straight (average 74.83%). The type of the Nasal Index is middle (70.0-84.9). The average of the Nasal Height (NH) of both male and female is 49.09 mm, the average of the Nasal Length (NL) is 41.99 mm, the average of the Nasal Breadth (NB) is 36.44 mm, the average of the Nasal Index is 74.93, but there is significant difference between male and female. The average of the Nasal Depth (ND) is 14.59 mm, the average of the Nasal Deep Index is 40.19; there is no significant difference between male and female. There is no difference between adults and youths, but there is marked difference between adults and teenagers, suggesting that the development of the nose of the Jingpo people tends to end up in youth.

Adolescent↗
PubMed1999

Transcriptional induction of p69 2'-5'-oligoadenylate synthetase by interferon-alpha is stimulated by 12-O-tetradecanoyl phorbol-13-acetate through IRF/ISRE binding motifs.

Protein kinase C (PKC) is required for transcriptional induction of 2'-5'-oligoadenylate (2-5A) synthetases by interferon (IFN)-alpha. Regulatory elements located in the 5'-flanking region of the p69 2-5A synthetase gene have been identified which are required for transcriptional stimulation by PKC. The region from -366 to -117 bp, relative to the translational start site, contains three sequence motifs that resemble interferon stimulated response elements/interferon regulatory factor elements (ISRE/IRF-E), which are required for stimulation of the IFN-alpha-response by the PKC activator, 12-O-tetradecanoyl phorbol-13-acetate (TPA). Constructs which have a deletion of the region containing IRF-Es located at -361 bp to -280 and at -246 to -172 bp do not respond to TPA treatment. Likewise, introduction of point mutations into either of these IRF-Es decreases stimulation of IFN-alpha induction by TPA and constructs containing point mutations in both upstream IRF-Es are nonresponsive to TPA. Binding of the inducible factor to the ISRE is abrogated in cells depleted of PKC by prolonged treatment with TPA. PKC appears to function as a signaling component in an IFN-independent pathway that increases the activity of IFN-alpha-regulated transcription factors in the nucleus.

2',5'-Oligoadenylate Synthetase↗
PubMed1999

Restriction landmark genome scanning for aberrant methylation in primary refractory and relapsed acute myeloid leukemia; involvement of the WIT-1 gene.

There is substantial evidence to suggest that aberrant DNA methylation in the regulatory regions of expressed genes may play a role in hematologic malignancy. In the current report, the Restriction Landmark Genomic Scanning (RLGS) method was used to detect aberrant DNA methylation (M) in acute myeloid leukemia (AML). RLGS-M profiles were initially performed using DNA from diagnostic, remission, and relapse samples from a patient with AML. Rp18, one of the eight spots found that was absent in the relapse sample, was cloned. Sequence analysis showed that the spot represented a portion of the WIT-1 gene on human chromosome 11p13. Rp18 was missing in the relapse sample due to a distinct DNA methylation pattern of the WIT-1 gene. Twenty-seven AML patients that entered CR after therapy (i.e., chemosensitive) were studied and only 10 (37%) of the diagnostic bone marrow (BM) samples showed methylation of WIT-1. However, seven of eight (87.5%) diagnostic BM samples from primary refractory AML (chemosensitive) showed methylation of WIT-1. The incidence of WIT-1 methylation in primary refractory AML was significantly higher than that noted in chemosensitive AML (P=0.018). Together, these results indicate that RLGS-M can be used to find novel epigenetic alterations in human cancer that are undetectable by standard methods. In addition, these results underline the potential importance of WIT-1 methylation in chemoresistant AML.

Acute Disease↗
PubMed1999

Prospective study of the value of serum chromogranin A or serum gastrin levels in the assessment of the presence, extent, or growth of gastrinomas.

BACKGROUND: Serum chromogranin A levels (CgA) are reported by some authors to be of clinical utility for assessing the presence or absence of a pancreatic endocrine tumor and tumor extent or growth. The aim of the current study was to assess this finding and compare the results with those from serum gastrin determinations (FSG) in a large cohort of patients with gastrinomas. METHODS: In 112 consecutive patients with the Zollinger-Ellison syndrome serum CgA and FSG levels were measured and correlated with disease activity, extent of disease, and the presence of multiple endocrine neoplasia type-1 (MEN-1) or gastric carcinoid tumors. RESULTS: Serum CgA levels drawn on 2 consecutive days correlated closely (P < 0.00001) as did serum gastrin levels. Serum CgA levels correlated significantly with FSG levels (P < 0.00001). Serum CgA and FSG levels were significantly higher in patients with active disease than in disease free patients (P < 0.00001). The sensitivity for the presence of disease was higher for CgA compared with FSG (92% vs. 80%; P = 0.021). However, the specificity of CgA was 67%. Serum CgA levels were not significantly different in the four disease categories (stable extrahepatic disease, increasing extrahepatic disease, stable liver metastases, and increasing liver metastases). FSG levels were significantly lower in patients with stable extrahepatic disease compared with those with increasing extrahepatic disease. However, both tumor markers decreased significantly with a gastrinoma resection in five patients. The presence of MEN-1 or a gastric carcinoid tumor did not influence the results. CONCLUSIONS: The results of the current study showed that serum CgA and FSG levels both are sensitive tumor markers for the detection of a gastrinoma; however, CgA levels have a relatively low specificity. Neither the magnitude of the serum CgA nor gastrin level correlated with tumor growth or tumor extent and therefore cannot be used to determine these variables. However, in contrast to some other studies, the results of the current study show that changes in serum CgA or gastrin in a given patient with time are related to the tumor extent and not to gastric mucosal changes due to hypergastrinemia.

Adult↗
PubMed1999

Protein synthesis-dependent and -independent induction of p69 2'-5'-oligoadenylate synthetase by interferon-alpha.

The 2'-5'-oligoadenylate (2-5A) synthetases are a family of interferon-alpha (IFN-alpha) inducible enzymes that block viral replication by activating a latent endonuclease during viral infections. In Ramos cells, induction of mRNAs for the intermediate isoform of 2-5A synthetase (p69) requires five-fold higher IFN-alpha than is required for induction of the small isoform (p40). The p40 and p69 isoforms are similarly induced between 1 and 24 h with maximal induction at 8 h. At 48 h, however, p69 is more strongly induced than p40. Induction of p69 and p40 between 1 and 24 h is protein synthesis independent whereas at 48 h, p69 induction becomes dependent on protein synthesis. Initial induction of both isoforms requires tyrosine kinase activation and is enhanced by activation of a separate signalling pathway by the tumour promoter, 12-0-tetradecanoyl phorbol-13-acetate (TPA). These data suggest that induction of the p40 is predominantly protein synthesis independent, whereas p69 induction occurs in two phases, an initial protein synthesis independent phase and a delayed protein synthesis dependent phase.

2',5'-Oligoadenylate Synthetase↗
PubMed1999

Follow-up of the original cohort with the Ahmed glaucoma valve implant.

PURPOSE: To study the long-term results of the Ahmed glaucoma valve implant in patients with complicated glaucoma in whom short-term results have been reported. METHODS: In this multicenter study, we analyzed the long-term outcome of a cohort of 60 eyes from 60 patients in whom the Ahmed glaucoma valve was implanted. Failure was characterized by at least one of the following: intraocular pressure greater than 21 mm Hg at both of the last two visits less than 6 mm Hg at both of the last two visits, loss of light perception, additional glaucoma surgery, devastating complications, and removal or replacement of the Ahmed glaucoma valve implant. Devastating complications included chronic hypotony, retinal detachment, malignant glaucoma, endophthalmitis, and phthisis bulbi; we also report results that add corneal complications (corneal decompensation or edema, corneal graft failure) as defining a devastating complication. RESULTS: The mean follow-up time for the 60 eyes was 30.5 months (range, 2.1 to 63.5). When corneal complications were included in the definition of failure, 26 eyes (43%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 76%, 68%, 54%, and 45%, respectively. When corneal complications were excluded from the definition of failure, 13 eyes (21.5%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 87%, 82%, 76%, and 76%, respectively. Most of the failures after 12 months of postoperative follow-up were because of corneal complications. CONCLUSIONS: The long-term performance of the Ahmed glaucoma valve implant is comparable to other drainage devices. More than 12 months after the implantation of the Ahmed glaucoma valve implant, the most frequent adverse outcome was corneal decompensation or corneal graft failure. These corneal problems may be secondary to the type of eyes that have drainage devices or to the drainage device itself. Further investigation is needed to identify the reasons that corneal problems follow drainage device implantation.

Female↗
PubMed1999

Longitudinal changes in optic disc topography of adult patients after trabeculectomy.

OBJECTIVE: To study longitudinal changes in optic disc topography after trabeculectomy in adult patients. DESIGN: Prospective case series. PARTICIPANTS: Twenty-five eyes of 25 patients undergoing trabeculectomy were enrolled. INTERVENTION: Images of the optic disc were obtained preoperatively and approximately 2 weeks, 4 months, and 8 months after surgery by use of a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). MAIN OUTCOME MEASURES: The topographic optic disc parameters (cup volume, cup area, rim volume, rim area, cup-disc area ratio, mean cup depth, maximum depth, cup shape, and height variation contour) were measured automatically for each image with the Heidelberg Retina Tomograph Software (version 1.11). RESULTS: Approximately 2 weeks after surgery, the mean preoperative intraocular pressure (IOP) of 19.3 mmHg (SD, 6.4 mmHg) decreased to 6.0 mmHg (SD, 3.6 mmHg), cup volume and mean cup depth decreased, height variation contour increased, and the cup shape parameter became more negative. Approximately 4 months after surgery, mean IOP was 9.7 mmHg (SD, 4.2 mmHg), and the only statistically significant change from preoperative values of optic disc parameters was in the cup shape measure. Approximately 8 months after surgery, there was no statistically significant change in any of the optic disc parameters compared with preoperative values, although IOP was 10.4 mmHg (SD, 5.9 mmHg). CONCLUSIONS: Changes in the optic disc that may be present 2 weeks after a trabeculectomy do not appear to persist 4 and 8 months later in eyes with advanced glaucomatous optic nerve damage, except for cup shape, which was different from preoperative values at 4 months but not at 8 months.

Aged↗
PubMed1999

Conopeptides from Conus striatus and Conus textile by cDNA cloning.

Conopeptide content in Conus textile and Conus striatus venoms were examined by polymerase chain reaction amplification of alpha-conopeptide cDNA and rapid amplification of 3' cDNA ends of O-superfamily conopeptide cDNA. Two new alpha-conopeptide sequences and six new O-superfamily conopeptide sequences from C. textile, four new O-superfamily conopeptide sequences, and four previously biochemically characterized conopeptide sequences from C. striatus were identified. The results suggest that this cDNA method is rapid and requires less material for the study of conopeptides.

Amino Acid Sequence↗
PubMed1999

Effect of microgravity on the cell cycle in the lentil root.

Characteristics of the cell cycle in cortical regions (0-0.6 mm from the root-cap junction) of the primary root of lentil (Lens culinaris L.) during germination in the vertical position on earth were determined by iododeoxyuridine labelling and image analysis. All cells were in the G1 phase at the beginning of germination and the duration of the first cell cycle was about 25 h. At 29 h, around 14% of the cortical nuclei were still in the G2 or M phases of the first cell cycle, whereas 53 and 33% of the nuclei were respectively in the G1 or S phase of the second cell cycle. In parallel, the cell cycle was analysed in root tips of lentil seedlings grown in space during the IML 2 mission (1994), (1) on the 1-g centrifuge for 29 h, (2) on the l-g centrifuge for 25 h and placed in microgravity for 4 h, (3) in microgravity for 29 h, (4) in microgravity for 25 h and placed on the 1-g centrifuge for 4 h. The densitometric analysis of nuclear DNA content showed that in microgravity there were less cells in DNA synthesis and more cells in G1 than in the controls on the 1-g centrifuge (flight and ground). The comparison of the sample grown continuously on the 1-g centrifuge in space and of the sample grown first in l-g and then in microgravity indicated that 4 h of microgravity modified cell cycle, increasing the percentage of cells in the G1 phase. On the contrary, the transfer from microgravity to the 1-g centrifuge (for 4 h) did not provoke any significant change in the distribution of the nuclear DNA content. Thus the effect of microgravity could not be reversed by a 4 h centrifugation. As the duration of the first cell cycle in the lentil root meristem is about 25 h, the results obtained are in agreement with the hypothesis that the first cell cycle and/or the second G1 phase was lengthened in absence of gravity. The difference observed in the distribution of the nuclear DNA content in the two controls could he due to the fact that the 1g control on board was subjected to a period of 15 min of microgravity for photography 25 h after the hydration of the seeds, which indicated an effect of short exposure to weightlessness. The mitotic index of cortical cells was greater on the 1-g centrifuge in space than in any other sample (flight and ground) which could show an effect of the centrifugation on the mitosis.

Cell Cycle↗
PubMed1999

The influence of thyroid hormone on myosin isoform composition and shortening velocity of single skeletal muscle fibres with special reference to ageing and gender.

This review summarizes the effects of altered thyroid hormone levels on the expression of myosin isoforms and contractility in single muscle fibres from fast- and slow-twitch muscles from young and old male and female rats. The differences between male and female hyperthyroid soleus muscles are suggested to be related to an interaction of thyroid hormones and sex hormones in the regulation of myosin gene expression. Additionally, the mismatch between the protein and mRNA levels of MyHCs between male and female hyperthyroid extensor digitorum longus (EDL) muscles raises the possibility of a gender-related difference in post-transcriptional, translational or post-translational regulation of MyHC isoforms by T3.

Aging↗
PubMed1999

Gender- and thyroid hormone-related transitions of essential myosin light chain isoform expression in rat soleus muscle during ageing.

In this brief review, the modulatory influence of essential myosin light chain (MLC) isoforms on muscle cell contractility is discussed. Specific interest is focused on the expression of the MLC1Sa and MLC1Sb isoforms in the slow-twitch soleus muscle in male and female rats, during ageing and after thyroid hormone treatment. According to two-dimensional gel electrophoresis analysis, the MLC1Sa/MLC1SB ratio increased during ageing in both males and females in parallel with the age-related decrease in shortening velocity reported in muscle fibres expressing the slow (type 1) myosin heavy chain (MHC) isoform. However, the MLC1Sa and MLC1Sb isoform expression responded to thyroid hormone treatment in a complex manner which did not parallel the age-related changes in shortening velocity reported in hyperthyroid animals. Thus, if MLC1Sa and MLC1Sb isoforms modulate shortening velocity in type 1 fibres, then other modulators of shortening velocity are not regulated by thyroid hormone in co-ordination with these essential MLCs.

Aging↗
PubMed1999

Long-term drusen study.

PURPOSE: To determine the yearly incidence of visual loss in the fellow eyes of patients with unilateral neovascular age-related macular degeneration (ARMD) and to assess the drusen characteristics portending the greatest risk for this outcome. METHODS: A total of 101 patients with unilateral exudative ARMD and drusen only in the fellow eye were entered into the study and prospectively followed up to 9 years. Visual acuity, color fundus photography, fluorescein angiography, and grading of drusen characteristics were obtained for each patient on entry into the study. Patients were followed at annual intervals with color fundus photography. The study endpoint was the development of choroidal neovascularization (CNV) or geographic atrophy (GA) in the fellow eye. RESULTS: Yearly incidence rates for the development of an endpoint lesion were between 5 and 14%. The risk of CNV peaked at 4 years and dissipated thereafter. Longer follow-up was associated with a slightly increased incidence of GA. Greater drusen number was most highly associated with the development of an endpoint lesion. Drusen size and confluence were also significant. CONCLUSIONS: The risk of CNV in patients with ARMD is heralded by an increase in the number, size, and confluence of drusen. This risk eventually declines and is followed by later increased risk of GA.

Aged↗