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Biomedical subjects

W Yu

Publications and source records attributed to W Yu.

At least 325 records · Page 18Linked to original sources
PubMed1994

The connexin43 gene is responsive to oestrogen.

Connexin43 is the major protein of gap junctions in heart and smooth muscle including the myometrium. Molecular cloning of the connexin43 gene reveals a similar organization to that exhibited by other connexin genes: the 5' untranslated region is interrupted by an 8.5 kilobase intron. The promoter region preceding the first exon contains a TATA box and AP-1 and AP-2 sites. In addition, a series of half-palindromic oestrogen response elements is present in this region. When this promoter is linked to the reporter gene luciferase, it drives the expression of luciferase constitutively in HeLa cells transfected with this luciferase-connexin43 promoter fusion construct. When the same cells are cotransfected with oestrogen receptor cDNA, an upregulation of luciferase expression by oestrogen occurs in a cell-specific manner.

Animals↗
PubMed1994

Expression of growth factors in early wound healing in rat skin.

Growth factors are a group of hormone-like polypeptides that have been shown to play a central role in different phases of wound healing. The expression of these growth factors in early wound healing has not been quantified, and the pattern and distribution of these growth factors in early wound healing has not been described completely. Furthermore the quantity and pattern of distribution of these growth factors have not been investigated in early wounds produced by various methods of surgical incision. Comparison of the rate of healing between the CO2 laser wound and the scalpel wound has produced conflicting results. The present immunohistochemical study uses polyclonal antibodies specific for epidermal growth factor (EGF), platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-beta), and basic fibroblast growth factor (bFGF) to observe the pattern and distribution of these growth factors in rat skin wound and elucidate whether there are differences in the expression of these growth factors which might account for the delayed healing of the CO2 laser wounds compared to the scalpel as has been observed by some authors. Our results indicate that EGF, TGF-beta, PDGF, and bFGF are expressed and distributed in same areas of the early skin wound. The area of expression of these growth factors was associated with presence of wound inflammatory cells and wound fibroblasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute-Phase Reaction↗
PubMed1994

Adaptation of enteroendocrine cells in response to jejunal-ileal transposition in the rat.

BACKGROUND/AIMS: Enteroendocrine cell subpopulations are uniquely distributed along the crypt-villus and cephalocaudal axes of the small intestine. These regional differences in enteroendocrine cell expression, which are maintained in spite of rapid turnover of the epithelium, serve as descriptive markers of physiological differences along the length of the bowel. This study aimed to determine the influence of luminal contents on the maintenance of regional differentiation patterns of enteroendocrine and enterocytic phenotypes. METHODS: Sections of jejunum and ileum were surgically transposed in rats, leaving the innervation and blood supply to the transposed segments intact. The animals were killed 1, 4, and 8 weeks after surgery. Enteroendocrine cell subpopulations and enterocytic cell markers were studied immunohistochemically. RESULTS: No change in regional expression patterns was seen in response to the altered luminal environment by any of the enterocytic markers and four of the five enteroendocrine cell subpopulation markers. Eight weeks after surgery, the number of gastrin-expressing enteroendocrine cells increased in ileal segments transplanted proximally. CONCLUSIONS: Although luminal signals can affect intestinal stem cells to alter their proliferation rates, the luminal environment has only limited effects on the regional-specific expression of enteroendocrine or enterocytic products.

Adaptation, Physiological↗
PubMed1994

Stereodynamic properties of the cooperative homodimeric Scapharca inaequivalvis hemoglobin studied through optical absorption spectroscopy and ligand rebinding kinetics.

The study of the thermal evolution of the Soret band in heme proteins has proved to be a useful tool to understand their stereodynamic properties; moreover, it enables one to relate protein matrix fluctuations and functional behavior when carried out in combination with kinetic experiments on carbon monoxide rebinding after flash photolysis. In this work, we report the thermal evolution of the Soret band of deoxy, carbonmonoxy, and nitric oxide derivatives of the cooperative homodimeric Scapharca inaequivalvis hemoglobin in the temperature range 10-300 K and the carbon monoxide rebinding kinetics after flash photolysis in the temperature range 60-200 K. The two sets of results indicate that Scapharca hemoglobin has a very rigid protein structure compared with other hemeproteins. This feature is brought out i) by the absence of nonharmonic contributions to the soft modes coupled to the Soret band in the liganded derivatives, and ii) by the almost "in plane" position of the iron atom in the photoproduct obtained approximately 10(-8) s after dissociating the bound carbon monoxide molecule at 15 K.

Animals↗
PubMed1994

Treatment of complex abdominal aortic aneurysms by a combination of endoluminal and extraluminal aortofemoral grafts.

PURPOSE: The purpose of this study was to test the hypothesis that abdominal aortic aneurysms (AAA) whose morphology makes them unsuited for repair with an endoluminal tube graft can be treated by a combination of a transluminally placed aortofemoral graft and a femorofemoral crossover graft. In addition the technique involves either ligation or balloon occlusion of the contralateral common iliac and internal iliac arteries in such a manner that excludes the AAA from the circulation. METHODS: We report the use of this technique in three male patients with 6.4 to 7.0 cm diameter AAA. Two had renal impairment and cardiac function too poor to permit open repair, and the third had an unfavorable abdomen caused by previous surgery and the presence of a permanent colostomy. Each patient had an individually tailored Dacron tube graft constructed on the basis of preoperative arteriograms and computed tomography scans. The grafts were delivered transluminally into the aorta through a sheath in the iliac arteries and anchored proximally with a stainless steel stent under radiographic control. The grafts were then anastomosed distally to the femoral artery. RESULTS: Recovery was complicated by a midgraft stenosis corrected by percutaneous balloon dilation in one patient, an episode of pulmonary edema in the second and an unexplained pyrexia in the third. Follow-up with duplex scanning confirmed normal flow through the grafts and the presence of thrombus between the prosthetic graft and the aneurysmal sac. CONCLUSIONS: We conclude that transluminal placement of an aortofemoral graft combined with a femorofemoral crossover graft is feasible in patients who are unsuited to repair with an endoluminal tube graft. The outcome with this technique is not known and requires further careful evaluation.

Aged↗
PubMed1994

The effect of laser irradiation on the release of bFGF from 3T3 fibroblasts.

Studies have shown that low-level laser irradiation increases the proliferation of fibroblasts in cell culture. The mechanism of action is unknown. Basic fibroblast growth factor (bFGF) is a multifunctional polypeptide that has been detected in most tissues and which supports cell proliferation and differentiation. The purpose of this study was to determine whether laser irradiation (660 nm) can stimulate production of bFGF from fibroblast cells in cell culture. Our study showed that fibroblasts irradiated with laser energy at 2.16 J/cm2 demonstrated increased cell proliferation and enhanced production of bFGF, whereas fibroblasts irradiated with laser energy at 3.24 J/cm2 neither demonstrated increased cell proliferation or an enhanced release of bFGF as compared to the control group. These results provide direct evidence that the proliferation of fibroblasts as a result of stimulation by low level laser irradiation may be associated with the autocrine production of bFGF from fibroblasts.

3T3 Cells↗
PubMed1994

Comparison of PCR with culture for detection of Ureaplasma urealyticum in clinical samples from patients with urogenital infections.

PCR was compared with culture for the detection of Ureaplasma urealyticum in 50 specimens, including sperm, urine, and prostate secretions, from hospital patients with urogenital infections. Five positive and a further four doubtful diagnoses were made by culture, whereas PCR detected U. urealyticum in 12 samples. PCR also was faster than culturing. The increased sensitivity and shorter time requirement of PCR support its further development for the diagnosis of U. urealyticum infection.

Adult↗
PubMed1994

A new nonstented balloon-expandable graft for straight or bifurcated endoluminal bypass.

PURPOSE: The aim of this study was to determine the feasibility of endoluminal grafting of aneurysms using a new design of nonstented endograft. METHODS: Initial studies were undertaken in bench models and by implantation of endografts into animal vessels. Between May 1992 and June 1994, endoluminal repair of aneurysms was undertaken in 47 patients (44 male, 3 female). A new balloon-expandable endoluminal graft was developed and has now been studied in 25 of these 47 cases. This graft does not require adjunctive use of a vascular stent because of its unique construction, which incorporates metallic implants (graft attachment device or "GAD") into the graft material. The design is applicable to endovascular grafting of occlusive arterial disease, as well as aneurysms. All patients were investigated by duplex scan, calibrated angiogram, and angio-CT scan and then allocated into groups that we defined according to the following criteria: group I, considered suitable for transfemoral implantation of a straight tube graft (n = 12); group II, unsuitable for transfemoral tube graft because of short neck of aneurysm, absent distal neck, or diseased iliac arteries (n = 10); and group III, peripheral aneurysms (n = 3). All patients were followed by clinical examination, duplex scan, and CT scan, with selective use of angiography. RESULTS: Intraluminal deployment of the graft was achieved in all 25 patients; however, 3 patients from group II subsequently required conversion to open procedures because of the following complications: (1) partial graft thrombosis resulting from inadvertent omission of systemic anticoagulation during deployment (n = 1); and (2) unsuccessful deployment of the contralateral limb of a bifurcated graft in the iliac artery (n = 2). Successful endoluminal repair was achieved in 100% of patients in groups I and III, compared to 70% in group II. CONCLUSIONS: These preliminary results (in a series of high-risk patients) have demonstrated that endoluminal abdominal aortic aneurysms repair with this graft can be achieved reliably and with low morbidity in patients who fulfill the selection criteria (group I) and in peripheral aneurysms (group III) but the results were less satisfactory in aneurysms that do not have a good proximal or distal neck or in patients with diseased iliac arteries (group II). Further modification of the bifurcated version in this graft design, together with improvements in access techniques and graft materials, is required for successful endoluminal grafting in a wider range of patients.

Aneurysm↗
PubMed1994

Endoluminal grafting of abdominal aortic aneurysms: causes of failure and their prevention.

PURPOSE: The aim of this study was to analyze the causes of failure of endoluminal grafting for abdominal aortic aneurysms (AAA) and to put forward proposals for preventing these failures. METHODS: Since May 1992, endoluminal repair of aneurysms was undertaken in 47 patients. Forty-three of these patients had AAAs and are the basis of this study. All procedures were nonurgent and were performed in the operating room with the patient draped for an open repair in the event of failed endoluminal repair. Radiographic guidance was used to pass the endografts into the aorta via a delivery sheath introduced through the femoral or iliac arteries. The configuration of the endografts was tubular (n = 28), tapered aortoiliac/aortofemoral (n = 11), and bifurcated (n = 4). RESULTS: Successful endoluminal repair was achieved in 34 of 43 (79%) patients. The remaining nine were terminated in favor of an open repair. The causes of failure were problems with access (2), balloon malfunction (1), stent dislodgment (3), graft thrombosis (1), and inability to deploy the contralateral limb of a bifurcated graft (2). All failed endoluminal repairs proceeded to successful open repair. There was no perioperative mortality in patients undergoing endoluminal repair or in those whose endoluminal repair was converted to open operation. CONCLUSIONS: The failures of endoluminal grafting have been analyzed. Methods of avoiding access problems, balloon malfunction, and stent dislodgment have been defined and recommendations made.

Aged↗
PubMed1994

The presence of a human chorionic gonadotropin-like protein and its binding site in Saccharomyces cerevisiae.

In this study, we characterize from Saccharomyces cerevisiae: 1) a protein that has immunological similarities to human chorionic gonadotropin (hCG), and 2) a binding site for this hCG-like protein which also binds hCG and human luteinizing hormone (hLH). Saccharomyces cerevisiae chorionic gonadotropin-like protein (ScCGLP) was purified in several steps. This protein when analyzed by SDS-PAGE, under nondenaturing conditions, produced two bands, one at 110-kDa, and another at 57.5-kDa. Under denaturing conditions, only the 57.5-kDa band appeared. This 57.5-kDa band also reacted in a Western blot, using a polyclonal antibody directed against hCG. Purified ScCGLP reacted in the following hCG immunoassays: 1) polyclonal rabbit anti-hCG equilibrium assay, 2) carboxyl-tail hCG equilibrium assay, 3) two equilibrium assays using monoclonal antibodies, and 4) free alpha-chain subunit equilibrium assay using a monoclonal antibody. Characterization of hCG/hLH binding sites in Saccharomyces cerevisiae was performed, and the ability of the ScCGLP to displace I125-hCG was also shown. Human CG and hLH were able to compete for I125-hCG binding to Saccharomyces cerevisiae blastospores (Kds of approximately 10(-8) M), while ScCGLP competed with higher affinity (Kd = 9.41 x 10(-10) M). The hCG-like immunoactivity was also present in Saccharomyces growth media, as well as in all brands of commercial beer studied.

Binding Sites↗
PubMed1994

[Clinical application of cluster analysis in repairing prosthesis ears]

Along with developments and progresses of microsurgery,plastic surgery became very often used method to reconstruct orofacial defects,but for missing ears the prosthesis methods are still a better way comparing surgery The main merits are :no wound,short treatment time,100% success rate,easily figure established.For simplified steps and saving time in the procedure of making prosthesis ears.300 different types ears from recording cases models are analysed and special different type wax-up ears and special models are made to provide different patients as needing for selection.

Journal Article↗
PubMed1994

[Study of cytochemical properties in the nucleus paragigantocellularis lateralis of rats].

The distribution of cell bodies containing serotonin (5-HT)-, substance-P (SP)-, L-enkephalin (L-ENK)- and neuropeptide Y (NPY)-like immunoreactivity (IR) in the nucleus paragigantocellularis lateralis (PGCL) of the rat was studied immunocytochemically. Perikarya containing 5-HT-, SP- or L-ENK-IR were found throughout the rostro-caudal extent of the PGCL. Large, well-staining 5-HT cells densely clustered rather near the ventrolateral surface of the medulla. SP- and L-ENK-IR were distributed more extensively and located more lateraly. A few of perikary on containing NPY-IR were found primarily in the area from the medium to caudal region. The results provided morphological basis for further study of the neurochemical properties of PGCL neurons involved in the regulation of cardiovascular, respiratory and other functions in the rat.

Animals↗
PubMed1994

Bone mass, rates of osteoporotic fractures, and prevention of fractures: are there differences between China and Western countries?

Fractures are one of the most common causes of disability in older women. The quantity and density of bone decreases with age. Most types of fractures increase as bone density declines. But most of the knowledge about causes and prevention of fractures comes from studies performed in Western countries. Asian women appear to have similar or slightly lower bone density that may be a result of their smaller size. They appear to have a lower risk of hip fracture than Whites, which may be a result of their shorter hip axis. The risks of other types of fractures in Chinese women is less well defined and reasons for differences in the rates of osteoporotic fractures between China and Western countries remain to be explored. A study is underway in Beijing to describe the risks and potential causes of fractures among older women in urban China. Randomized trials in Western countries have demonstrated that calcium and vitamin D, estrogen, calcitonin, or bisphosphonates can reduce the rate of fractures. increased intake of calcium and vitamin D may be the most effective approach to preventing fractures in China, but this should be tested in a randomized trial.

Asian People↗
PubMed1994

Microtubule fragmentation and partitioning in the axon during collateral branch formation.

Axons within the brain branch principally by the formation of collaterals rather than by bifurcation of the terminal growth cone (O'Leary and Terashima, 1988). This same behavior is recapitulated in cultures of embryonic hippocampal neurons (Dotti et al., 1988), rendering them ideal for studies on the cell biological mechanisms underlying collateral branch formation. In the present study, we focused on changes in the microtubule (MT) array that occur as these axons branch. In particular, we explored the mechanism by which MT number is locally increased to accommodate the need for more MTs during collateral branch formation. Serial reconstruction analyses indicate that MT number increases by severalfold and that MT length decreases correspondingly within the parent axon in the discrete region giving rise to the branch. These observations strongly suggest that MTs within the parent axon undergo a local fragmentation in this region, and hence raise the possibility that a portion of these new MTs might be destined for transport into the branch. To address this latter issue, we used quantitative immunofluorescence to compare the proportion of newly assembled to total MT polymer in different regions of the axon. As previously reported (Brown et al., 1992), the region of the axon contiguous with the terminal growth cone is particularly rich in newly assembled polymer. In contrast, there was no distinguishable difference in the proportion of newly assembled polymer in the newly formed collateral branches compared to the shaft region of the parent axon. These results indicate that the MTs within the newly formed collateral branches are on average assembled at the same time as those within the parent axon, and thus strongly suggest that the MTs in the collateral branch were assembled in the parent axon and then translocated into the branch. We conclude on the basis of these observations that collateral branch formation requires a local fragmentation of MTs within the parent axon, followed by the partitioning of a portion of the MT fragments into the branch. These short MTs presumably then resume their movement and elongation down the collateral branch as well as down the parent axon for the steady and orderly increase of both MT arrays.

Animals↗
PubMed1994

[Kaschin-Beck's disease in children's wrists: radiographic findings].

Based on the analysis of hand radiographs in 208 children with Kaschin-Beck's disease, the author's chief conclusions are as follow: The more severe Kaschin-Beck's is, the more opportunity the carpals have to be involved. Generally speaking, the capitatum and hamatum are frequently involved if the disease involves the carpals.

Adolescent↗
PubMed1994

Changes in microtubule number and length during axon differentiation.

Hippocampal neurons in culture initially extend several minor processes that are approximately 20 microns in length. The first minor process to grow approximately 10 microns longer than the others will continue to grow rapidly and become the axon (Goslin and Banker, 1989). We sought to define changes in the microtubule (MT) array that occur during axon differentiation. In theory, axon differentiation could involve an increase in MT number, MT length, or some combination of both. To address this issue, we first serially reconstructed the entire MT array of a minor process from a cell whose axon had not yet differentiated. This minor process contained 182 MTs that ranged in length from 0.14 to 20.09 microns. The average MT length was 3.87 +/- 3.83 microns, and the total MT length was 704 microns. We then reconstructed the MT arrays of a minor process and the 56 microns axon from a cell that had undergone axon differentiation. The minor process contained 157 MTs that ranged in length from 0.24 to 17.95 microns. The average MT length was 3.91 +/- 4.84 microns, and the total MT length was 600 microns. The axon contained 1430 MTs that ranged in length from 0.05 to 40.14 microns. The average MT length was 4.02 +/- 5.28 microns, and the total MT length was 5750 microns. These data indicate that a shift occurs toward shorter as well as longer MTs, but that virtually no change in average MT length occurs during axon differentiation. Thus, elongation of existing MTs cannot account for the major expansion of the MT array that occurs as a minor process becomes an axon. In contrast, the number of MTs increases by approximately 10-fold as a minor process differentiates and grows into an axon of the length we analyzed. Based on these data, we conclude that the MT array of a minor process is substantially expanded as it differentiates into an axon, and that the principal mechanism by which this expansion occurs is the copious addition of new MTs.

Animals↗
PubMed1994

An in vitro model for the effects of estrogen on neurons employing estrogen receptor-transfected PC12 cells.

Estrogen alters neurite outgrowth, neuritic spine development, and synaptogenesis in estrogen-responsive areas of the rat brain. However, examination of the specific effects of estrogen on neurons in vivo has been difficult. An in vitro model for the effects of estrogen on neurons was developed, using the PC12 rat pheochromocytoma cell line. Wild-type cells (PC12-WT) were stably transfected either with an expression vector coding for the full-length cDNA for the human estrogen receptor (hER), or with a control vector. Resultant clones were isolated, screened for incorporation of vector and expression of ER mRNA and protein, and analyzed for morphologic responses to estrogen. PC12-WT, NEO9 (ER-negative), and SER8 (ER-positive) cells exposed to 100 ng/ml NGF exhibited dose-responsive neurite outgrowth within 2 d by light microscopy (LM). Coadministration of 10(-10) to 10(-9) M estradiol (E2) had minimal effects on neurite outgrowth, neuritic spine development, or interneuritic connections in NEO9 or PC12-WT cells, but in SER8 cells E2 led to additive and dose-dependent increases in neurite outgrowth, spine development, and interneuritic connectivity. Coincubation of SER8 cells with E2 and the antiestrogen ICI 164,384 negated estrogenic effects on spine development and interneuritic connectivity. At the electron microscopic (EM) level, intercellular abutments of NEO9 or PC12-WT cells contained few and rudimentary gap junctions, with no increase by E2. However, SER8 cells exhibited augmented basal frequencies of gap junctions that increased with E2 incubation. Microinjection of Lucifer yellow into PC12-WT and NEO9 cells demonstrated low frequencies of dye coupling and no change with E2, but SER8 cells demonstrated increased dye-coupling frequency with E2 coincubation. The results suggest that SER8 cells recapitulate estrogen effects on neurons in vivo. Estrogen appears to induce an inherent neural morphologic program in estrogen receptor (ER)-containing cells. These three cell lines provide a unique in vitro system for studying mechanisms of estrogen-neuron interactions.

Animals↗