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Biomedical subjects

H Yuan

Publications and source records attributed to H Yuan.

At least 145 records · Page 8Linked to original sources
PubMed1997

Promotion of osteogenesis by a piezoelectric biological ceramic.

Hydroxyapatite (HA) ceramic and piezoelectric biological ceramic, hydroxyapatite and barium titanate (HABT), were implanted in the jawbones of dogs. Histological observation showed that, compared with HA ceramics, HABT promoted the growth and repair of the bone significantly, the tissue growth around the HABT ceramic was direction-dependent, the collagen arranged orderly and the bone grew orderly. The order growth of the bone increased the efficiency of osteogenesis on the surface of the implanted HABT ceramics.

Animals↗
PubMed1997

[Medicated stainless steel ring-165, medicated gamma-intrauterine devices and TCu220C: a multicenter comparative study].

OBJECTIVE: A five-year multicenter comparative study was conducted to observe the clinical efficacy, side effects, and menstrual blood loss (MBL) of medicated stainless steel ring 165 (MSSR-165), medicated gamma-Intrauterine devices (gamma-IUD) (both containing indomethacin and copper) and TCu220C for exploring new kinds of IUD to reduce MBL after IUD insertion. METHODS: MSSR-165 and medicated gamma-IUD, with TCu220C as a control, were randomly inserted (one thousand in each group) in women 12 hospitals nation wide in October 1988. Follow-ups were performed at the time of 3, 6, 12, 24, 36, 48 and 60 months after IUD insertion. The efficacy of the IUDs was calculated with life table method. A quantitative comparison of MBL was made before and 3, 6, 12, 24, 36 and 60 months after the IUD insertion in 20 volunteers. RESULTS: At the end of 5 years, the pregnancy rates of MSSR-165, medicated gamma-IUD and TCu220C were 3.2, 2.7 and 3.2. The expulsion rates were 7.7, 2.3 and 2.4, while the removal rates for medical reasons were 5.0, 3.8 and 6.4. The cumulative continuation rates were 79.8, 88.7 and 84.9 per 100 women respectively. The average total bleeding time in the first year of MSSR-165 was 22 days, the shortest one among the three IUDs. The quantitative comparison of MBL showed that the gamma-IUD reduced the MBL and the TCu220C increased the MBL apparently. CONCLUSION: With good clinical efficacy, short menstrual bleeding time, as well as the same appearance and insertion technic as stainless steel ring, the MSSR-165 will be easily accepted at the grass root level. The gamma-IUD had good clinical efficacy and higher continuation rate, whereas the side effect of bleeding was not obvious. Both medicated SSR165 and gamma-IUD could be recommended for promotion.

Adult↗
PubMed1996

Induction of vascular endothelial growth factor by insulin-like growth factor 1 in colorectal carcinoma.

Vascular endothelial growth factor (VEGF) is an angiogenic hormone that is produced by and supports the growth of many types of malignancies. The present study shows that insulin-like growth factor 1 (IGF-I), a mitogen that promotes the propagation of cancers through autocrine and paracrine mechanisms, increases the expression of mRNA for VEGF and production of VEGF protein by COLO 205 colon carcinoma cells. IGF-I also induces expression of VEGF mRNA in SW620, LSLiM6, and HCT15 colon carcinoma cells showing that this is a common response to IGF-I. Whereas IGF-I induced VEGF mRNA in each cell line examined (2.3-12-fold), it induced proliferation only in COLO 205 and LSLiM6 cells. Thus, the proliferative response induced by IGF-I and its ability to induce VEGF occur through distinguishable mechanisms. IGF-I increases the cellular content of VEGF mRNA by increasing the rate of transcription (5-fold after 4 h) and also by increasing the half-life of VEGF mRNA (0.6 +/- 0.07 h in control cells to 2.0 +/- 0.37 h in IGF-I-treated cells). Monoclonal antibody (alphaIR3) directed against the type 1 IGF receptor significantly attenuated the ability of IGF-I to promote expression of VEGF mRNA. Interestingly, by itself alphaIR3 acted as a weak agonist and induced a modest increase in the cellular content of VEGF mRNA. alphaIR3 also promoted tyrosine phosphorylation of the beta subunit of the IGF-I receptor, and the magnitude of this response was comparable with that induced by IGF-I. These observations point to a nonlinear relationship between activation of the IGF-I receptor and induction of VEGF mRNA. Thus, in addition to its direct, growth stimulatory effect on transformed cells, IGF-I induces the expression of VEGF which can promote the progression of cancer by regulating the development of new blood vessels.

Colorectal Neoplasms↗
PubMed1996

Segregation analysis of alcoholism in high density families: a replication.

We have previously reported segregation analysis of alcoholism in 35 multigenerational families, each ascertained through a pair of male alcoholics by using the mixed model implemented by POINTER. This analysis suggested that liability to alcoholism was, in part, controlled by a major effect with or without additional multifactorial effects. The hypothesis that the major effect was explained by a single genetic locus with strictly mendelian transmission was rejected. The purpose of the present analysis was to use the regressive model implemented by the REGD program from the Statistical Analysis for Genetic Epidemiology computer package (S.A.G.E.) to confirm by replication that a major effect was present in these 35 families. Evidence for the major effect found in Pointer was replicated in the present analysis by using S.A.G.E. Also, we found strong evidence for parental effects that were independent of the major locus transmission from ancestral relatives to children. Mendelian transmission of this major effect was rejected when models incorporated parental effects. When the major effect was calculated adjusting for parental phenotypes, the relative risk of affection for children was about twice as high with affected parents vs. unaffected parents.

Adolescent↗
PubMed1996

Sex differences in corticosteroid binding in the rat brain: an in vitro autoradiographic study.

Several previous studies have raised the possibility of sex differences in the distribution of corticosteroid receptors in the brain. The direction and magnitude of these differences have, however, remained controversial. In the present study, we have re-examined the concentrations of mineralocorticoid (MR) and glucocorticoid (GR) receptors in the brains of male and female rats at varying times (1 to 6 days) after combined gonadectomy (GDX) and adrenalectomy (ADX). Cytosol binding assays confirmed the presence of higher MR levels in short-term (3-day) GDX-ADX males. This difference disappeared by 6 days after surgery, as receptor levels in females rose to be equivalent to those in males. Using an improved in vitro autoradiographic method, the distribution of MR and GR was studied in males and females 3 days after GDX-ADX. The distribution of MR and GR in the brains of these rats was similar in the two sexes. MR binding in the male, however, was significantly greater than that in the female throughout the principal cell fields of the hippocampus. Measurements of circulating corticosterone levels at the time of GDX-ADX suggest that this sex difference may reflect a more rapid recovery of the MR system in males than in females following the stress-induced rise in corticosterone secretion occurring at the time of surgery.

Adrenal Cortex Hormones↗
PubMed1996

Osteogenesis in extraskeletally implanted porous calcium phosphate ceramics: variability among different kinds of animals.

Synthetic porous calcium phosphate ceramics (HA/TCP) were implanted intramuscularly and subcutaneously in dogs, pigs, goats, rabbits and rats, designed to make a comparative study of the host tissue responses to porous HA/TCP ceramics in different kinds of animals. Specimens were harvested at 15, 30, 45, 60, 90 and 120 days after implantation. Decalcified and undecalcified sections were made and examined by light microscopy. Obvious bone formation could be detected in some specimens harvested from dogs and pigs after 45 days intramuscular implantation or after 60 days subcutaneous implantation. At days 90 and 120, an extensive amount of bone formed in all specimens implanted in dogs and pigs. However, no histologically detectable bone formation was observed in any specimen implanted intramuscularly and subcutaneously in goats, rabbits and rats until 120 days. It is demonstrated from this finding that the synthetic porous calcium phosphate ceramics are capable of inducing osteogenesis when implanted in non-bony sites, but this ability varies between different kinds of animals. Earlier periods of observation in specimens harvested from dogs showed that bone differentiation in the pore regions of the ceramics follows a complex process involving invasion of the fibrovascular connective tissues at day 15, appearance of polymorphic mesenchymal cells near the invading vasculature and at the interface with the ceramics at day 30, differentiation of osteoblasts and formation of bone matrix in direct contact with the surface of the ceramics at day 45, and finally remodelling of the fibrous connective tissue into an extensive amount of bone at days 60, 90 and 120.

Animals↗
PubMed1996

Release of CuPTSM from human serum albumin after addition of fatty acids.

Copper-62 labeled pyruvaldehyde bis (N4-methyl-thiosemicarbazonato) copper(II), CuPTSM, has been used to probe tissue perfusion by means of positron emission tomography. Despite promising results from animals, problems have been encountered in the use of 62CuPTSM to quantitate regional myocardial blood flow in humans. Ultrafiltration and plasma/erythrocyte partitioning studies with radiotracer have previously shown that CuPTSM is bound much more strongly by human serum albumin (HSA) than by dog serum albumin (DSA), limiting its ability to freely diffuse from blood into tissue. In this study, it is confirmed by electron spin resonance (ESR) that CuPTSM strongly binds to HSA with an apparent gparallel value of 2.12 and an apparent Aparallel value of 186 G. It is also shown that both spin-labeled stearic acid (5-SASL) and nonspin-labeled stearate inhibit CuPTSM binding to HSA. CuPTSM is completely released from HSA when the ratio of 5-SASL to HSA is 5:1. When pure sodium stearate is used, the binding of CuPTSM significantly decreased, about 73% of CuPTSM is released with a ratio of 4:1 stearate to HSA. These results highlight a means of liberating CuPTSM from HSA.

Electron Spin Resonance Spectroscopy↗
PubMed1996

Timing of surgical decompression and fixation of acute spinal fractures.

A retrospective evaluation of 138 patients requiring operative decompression, reduction and fixation of spinal injuries between January 1986 and April 1989 was conducted. The variables of timing and method of operative intervention, level and classification of fracture, associated injuries, injury severity score (ISS), associated neurologic deficits, length of intensive care unit and hospital stays, and projected costs were analyzed for correlation with postoperative complications (pulmonary, skin, urinary, other). Four subgroups were identified: group IA patients underwent surgery within 72 h of injury and had an ISS of < 18; group IB patients underwent surgery after 72 h and had an ISS of < 18; group IIA patients underwent surgery within 72 h and had an ISS of > or = 18; and group IIB underwent surgery after 72 h and had an ISS of > or = 18. There was no statistically significant difference in the incidence of medical complications in patients comparing groups IA and IB. Group IIB patients had a statistically significant higher rate of morbidity than did group IIA. A separate group of patients with cervical spine injuries with neurologic deficit was analyzed by the same statistical analysis. Irrespective of associated injuries, all had fewer complications if they underwent surgery within 72 h. Morbidity was higher in patients with a neurological deficit compared with neurologically intact patients. Surgical decompression, reduction, and/or fixation of spinal fractures within the first 72 h is indicated in patients with multiple trauma (ISS > or = 18) and cervical injuries with a neurological deficit.

Adolescent↗
PubMed1996

Autonomic, electroencephalographic, and myogenic activity accompanying startle and its habituation during mid-childhood.

This study investigated (a) possible associations of the large individual variation in startle, with accompanying autonomic, central nervous system, and myogenic activities in a habituation paradigm; and (b) the patterns of habituation of these variables. Startle blinks to 40 noise bursts, heart rate, alpha activity, and orbicularis oculi electromyographic (EMG) activity preceding and following each startle response were measured in 40 normal 7-11-year-old boys. Startle amplitude and its habituation were independent of association with either initial values or successive changes in the autonomic, alpha, and EMG activities; whereas startle habituated, pre- and poststartle myogenic, alpha, and cardiac activities failed to habituate. Tonic cardiac activity was facilitated, suggesting sensitization of state, as proposed in the dual-process theory of habituation.

Autonomic Nervous System↗
PubMed1996

Video-assisted thoracic corpectomy and spinal reconstruction: a biomechanical analysis of open versus endoscopic technique.

The purpose of this study is to evaluate the technique of video-assisted thoracic surgery (VATS) to perform corpectomy and spinal reconstruction with the Harrington rod and polymethylmethacrylate construct, and to compare the biomechanical stability of the constructs created with both open thoracotomy and VATS technique. Fourteen farm-raised pigs were divided into two groups. Group I underwent thoracic corpectomy using a VATS approach and group II had the same procedure performed through a traditional thoracotomy. The stiffness (newtons per millimeter) for the non-destructive tests for each loading mode are flexion-compression (open 124.4 +/- 124.9; VAT 75.8 + 29.9); extension-compression (open 165.8 + 41.8: VATS 96.5 + 31.2); pure compression (open 231.4 + 126.4; VATS 264.6 + 184.3). The difference between group I (VATS) and group II (open) in extension compression is statistically significant. Although not statistically significant, the results also show the group II (open) specimens to be stiffer in flexion-compression and the group I (VATS) specimens to be stiffer in pure compression. Although corpectomy and spinal reconstruction can be performed with the VATS technique, the constructs obtained endoscopically may not have the same strength as those constructs obtained via an open procedure.

Animals↗
PubMed1996

An investigation into the possible use of hydrocyclones for the removal of yeast from beer.

This investigation has focused on the importance of hydrocyclone design and running conditions for the removal of yeast from suspensions. Experiments have been carried out using both a model system of yeast grown in suspension cultures and rough beer. It appeared that the most important factor was the design of the hydrocyclone with a positive correlation between higher residence times and acceleration with the efficiency of separation. The other factor that affected the separation efficiency was the concentration of the yeast suspension and a new phenomenon of a lower efficiency of hydrocyclones at very low feed concentrations has been observed. The separation efficiency was also affected by temperature with lower temperatures giving poorer separations.

Beer↗
PubMed1996

The effect of a combined approach to schistosomiasis control on the transmission of Schistosoma japonicum in Xingzi of Poyang Lake area, China.

The impact of a combined approach to schistosomiasis control from 1987 to 1989 and mass chemotherapy from 1992 to 1994 was studied in a rural community in Xingzi county in the northwest corner of Poyang Lake in Jiangxi Province, China. Humans, cattle, buffalo and pigs were known potential reservoirs of Schistosoma japonicum. Transmission occurs during water contact on and around seasonally flooded marshes that are used for grazing, the harvesting of grass and fishing. Humans and livestock underwent yearly selective mass chemotherapy, and snails were eliminated through ploughing and compacting of the marshland in the spring of 1988. Transmission was monitored through the determination of annual re-infection rates in samples of the human population, the annual examination of piles of feces from animals and humans in the marshland, the annual collection and examination of intermediate snail hosts, and the exposure to potentially polluted water and subsequent examination of sentinel mice. Schistosomiasis prevalence among humans and animals declined sharply as soon as mass chemotherapy was implemented. Snail density decreased even before mollusc control was started, possibly indicating a high variability of this indicator. The infection rates of snails and sentinel mice reached zero after a single application of mollusc control. The results underline the importance of single infected water buffalo for the transmission of schistosomiasis. Since the impact stopped for two years (1990-1991), the schistosomiasis prevalence rose quickly. Mass chemotherapy was an effective means to curb the prevalence of schistosomiasis in this area, but the effects were only maintained for one or two years in the marsh zone.

Animals↗
PubMed1996

[Negative binomial distribution of eggs of Schistosoma japonicum in stool].

To understand the nature of distribution of schistosoma japonicum (S. japonicum) eggs in stool of the infected individuals, it is assumed that if regression coefficient b approaches two in the equation lg (v) = a + blg(m), with a larger mean of egg counts (m), they can be considered compatible with negative binomial distribution. Results of this study showed egg counts of S. japonicum in stool of the same infected individual on different days and in male and female population can be described by negative binomial distribution, with 95 percent confidence intervals of coefficient of regression 1.3006-2.2956, 1.6109-1.9703, 1.7060-2.1589, and 1.5507-2.2359, respectively. Goodness of fit tests for the observed data indicated that fitting for negative binomial distribution was good. It suggests that the method of moments (coefficient of regression) can be used to determine whether the observed distribution of frequencies is compatible with a negative binomial one.

Animals↗
PubMed1995

Developmental-specific activity of the FGF-4 enhancer requires the synergistic action of Sox2 and Oct-3.

Fibroblast growth factor 4 (FGF-4) has been shown to be a signaling molecule whose expression is essential for postimplantation mouse development and, at later embryonic stages, for limb patterning and growth. The FGF-4 gene is expressed in the blastocyst inner cell mass and later in distinct embryonic tissues but is transcriptionally silent in the adult. In tissue culture FGF-4 expression is restricted to undifferentiated embryonic stem (ES) cells and embryonal carcinoma (EC) cell lines. Previously, we determined that EC cell-specific transcriptional activation of the FGF-4 gene depends on a synergistic interaction between octamer-binding proteins and an EC-specific factor, Fx, that bind adjacent sites on the FGF-4 enhancer. Through the cloning and characterization of an F9 cell cDNA we now show that the latter activity is Sox2, a member of the Sry-related Sox factors family. Sox2 can form a ternary complex with either the ubiquitous Oct-1 or the embryonic-specific Oct-3 protein on FGF-4 enhancer DNA sequences. However, only the Sox2/Oct-3 complex is able to promote transcriptional activation. These findings identify FGF-4 as the first known embryonic target gene for Oct-3 and for any of the Sox factors, and offer insights into the mechanisms of selective gene activation by Sox and octamer-binding proteins during embryogenesis.

Amino Acid Sequence↗
PubMed1995

Molecular and functional characterization of a partial cDNA encoding a novel chicken brain melatonin receptor.

An approach based on homology probing was used to clone a partial cDNA encoding a novel melatonin (ML) receptor (MLR) from chicken (Gallus domesticus) brain. Based on available deduced amino-acid sequence, the chicken MLR (cMLR) displayed greater sequence homology to the frog (Xenopus) MLR than cloned human/mammalian receptors, with overall identities of 73% and 66%, respectively. In order to gain functional expression, a chimeric frog/chicken (flc)MLR was constructed in which the 5' end of the cMLR, including the N-terminus, TM1 and part of the first intracellular loop was substituted by fMLR sequence. [125I]Iodo-ML bound with high affinity (Kd of approximately 35 pM) to COS-7 cells transiently expressing the flcMLR in a saturable and guanine nucleotide-sensitive manner with the following rank order of potency: 2-iodo-ML > ML > 6-Cl-ML > S20750 > 6-OH-ML > S20642 > S20753 > N-acetyl-5HT >> 5-HT. Estimated Ki values for these compounds at the flcMLR correlated well to those obtained in native chicken brain membranes. In line with the observed structural similarity to the fMLR, the flcMLR exhibited affinities for ML, 6-Cl-ML and 6-OH-ML approximately 10-fold lower than mammalian receptors. Functionally, opposing interactions between ML and dopamine receptor signal transduction pathways were observed with ML potently inhibiting dopamine D1A-receptor-mediated cAMP accumulation in cells (HEK-293) transiently co-expressing these receptors. cMLR mRNAs were found expressed in chicken brain and kidney with trace levels observed in the lung. The availability of cloned vertebrate MLRs distinct at both the amino acid and pharmacological level from their mammalian counterparts may now allow for the identification of those amino-acid residues and structural motifs that regulate ML-binding specificity and affinity.

Adenylyl Cyclase Inhibitors↗
PubMed1995

Comparison of [125I]iodomelatonin binding sites in infant cerebellum of sudden infant death syndrome and non-sudden infant death syndrome.

[125I]Iodomelatonin bindings sites in human infant cerebellum were studied by radioligand receptor binding assay and in vitro quantitative autoradiography. The binding sites characterized in membrane preparations revealed saturable, reversible and highly specific binding sites with a Kd value of 21.2 +/- 8.33 pM and a Bmax value of 2.02 +/- 0.52 fmol/mg protein. 10 microM of GTP gamma S significantly reduced the binding capacity, suggesting the possible G-protein coupling of the binding sites. Autoradiographic study showed that the labelling was mainly located in the cerebellar cortex. On comparison of the binding parameters from cerebellum of sudden infant death syndrome (SIDS) and non-SIDS infants, no significant change in binding capacity and binding affinity was detected. These findings suggest that the binding sites in cerebellum may not be related to the etiology of SIDS.

Analysis of Variance↗