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Biomedical subjects

G Yang

Publications and source records attributed to G Yang.

At least 127 records · Page 7Linked to original sources
PubMed2000

Reduced infiltration of tumor-associated macrophages in human prostate cancer: association with cancer progression.

Tumor-associated macrophages (TAMs) are highly active immune effector cells that may either positively or negatively regulate the growth of various malignant cells, depending on the biological context. However, the role of TAMs in human prostate cancer progression is unclear. TAMs were immunohistochemically labeled using a monoclonal (CD68) antibody in radical prostatectomy specimens derived from 81 prostate cancer patients. CD68-positive cells were counted with the aid of a microscope and expressed as macrophage index (MphiI), including TAMs/mm2 total tumor tissue (MphiItotal), TAMs/mm2 tumor stroma (MphiIstroma), and TAMs/mm2 cancer cell area (MphiIcancer). MphiIs were analyzed in association with patients' clinical and pathological stage, recurrence status, and histological grade of the cancer. There were significant inverse relationships between MphiItotal and MphiIstroma and clinical stage (P = 0.016 and P = 0.006, respectively). Reduced MphiItotal was also associated with the presence of positive lymph nodes (P = 0.010). Interestingly, although all of the MphiIs differed between Gleason score groups, only MphiIcancer was positively associated with Gleason score. Univariate analysis of MphiItotal and multivariate analysis of MphiItotal with specific pathological markers revealed that MphiItotal was an independent predictor for disease-free survival after surgery (Cox proportional hazard model, P = 0.044 and P = 0.007, respectively). For patients with high MphiItotal (> or = 185.8, the mean MphiItotal value), the disease-free probability 5 years after surgery was 0.75, which was significantly higher than for those with low MphiItotal (0.31, P = 0.0008). Additional immunohistochemical studies that evaluated cytotoxicity-related biomarkers in stroma-associated mononuclear cells suggested reduced functional activities in highly aggressive prostate cancer compared with less aggressive disease. Our results indicate that reduced MphiItotal is a novel prognostic marker for prostate cancer.

Aged↗
PubMed2000

Trends in colorectal cancer rates in urban shanghai, 1972-1996, in relation to dietary changes.

PURPOSE: In urban Shanghai, the largest industrial and commercial city in China, the age-adjusted (world standard) incidence rates for colorectal cancer increased from 14.5 to 23.3 per 10(5) men and from 12.1 to 20.3 per 10(5) women between 1972 and 1996. This change was even more pronounced for colon cancer, whose incidence rates doubled from 5.95 to 13.7 per 10(5) men and from 5.77 to 12.5 per 10(5) women. The reasons for the rapid increases in cancer rates are not fully understood, but may involve dietary exposures that have changed substantially over the past two decades.METHODS: We calculated Pearson correlation coefficients (r) between colorectal cancer rates and the dietary factors of grain, vegetable oil, pork, poultry and vegetable consumption over the period of 1972 through 1996 in urban Shanghai.RESULTS: Statistically significant positive associations were observed between colon cancer rates and per capita consumption of vegetable oil (r = 0.91 for men, r = 0.94 for women), poultry (r = 0.90 for men, r = 0.90 for women), and pork (r = 0.78 for men, r = 0.81 for women). The correlation coefficients were not statistically significant between colon cancer and per capita consumption of grain (r = 0.38 for men, r = 0.37 for women) or vegetables (r = 0.16 for men, r = 0.14 for women). Similar weaker associations were observed between rectal cancer rates and vegetable oil, pork and poultry consumption.CONCLUSIONS: The findings in our study suggest that increases in dietary fat, poultry and pork intake may play a role in the rising colorectal cancer rates in Shanghai.

Journal Article↗
PubMed2000

Stellate neurons mediate functional hyperemia in the cerebellar molecular layer.

Mice lacking cyclin D2 have a profound reduction in the number of stellate neurons in the cerebellar molecular layer. We used cyclin D2-null mice to study the contribution of stellate neurons in the increase of cerebellar blood flow (BFcrb) produced by neural activation. Crus II, a region of the cerebellar cortex that receives trigeminal sensory afferents, was activated by stimulation of the upper lip (5-30 V; 10 Hz), and BFcrb was recorded at the activated site by the use of a laser-Doppler flow probe. In wild-type mice, upper lip stimulation increased BFcrb in crus II by 32 +/- 2%. The rise in BFcrb was attenuated by 19% in heterozygous mice and by 69% in homozygous mice. In contrast to the cerebellum, the increases in somatosensory cortex blood flow produced by upper lip stimulation was not attenuated in D2-null mice. The field potentials evoked in crus II by upper lip stimulation did not differ between wild-type and D2-null mice. Stellate neurons are a major source of nitric oxide (NO) in the cerebellar molecular layer. The neuronal NO synthase inhibitor 7-nitroindazole attenuated the vascular response to crus II activation in wild-type mice but not in D2-null mice, suggesting that stellate neurons are the major source of NO mediating the vascular response. The data provide evidence that stellate neurons are a critical link between neural activity and blood flow in the activated cerebellum and that NO is the principal effector of their vascular actions.

Animals↗
PubMed2000

Regional difference of neuronal vulnerability in the murine hippocampus after transient forebrain ischemia.

We have investigated the regional difference of neuronal vulnerability within the hippocampus in the C57BL/6 strain mice after forebrain ischemia. Both common carotid arteries of fifty mice were occluded for 12 min and the mouse brain was examined with cresyl violet staining. The CA4 sector was found to be the most vulnerable within the hippocampus. The CA2 and the medial CA1 sector was the 2nd and 3rd most vulnerable regions. However, The lateral part of the CA1 sector, CA3 sector and the dentate gyrus were resistant to ischemic insult.

Animals↗
PubMed2000

Mouse prostate reconstitution model system: A series of in vivo and in vitro models for benign and malignant prostatic disease.

BACKGROUND: An elucidation of the complex, morphological and molecular changes that underlie benign and malignant prostatic disease will likely lead to improved methods of diagnosis and therapy for those disorders. To identify and understand the interrelation of the phenotypic and genetic changes inherent in these important diseases requires the development and use of in vivo and in vitro models that closely mimic specific aspects of the disease process. Once the suspected molecular underpinnings of prostatic disease are uncovered, in vivo and in vitro models will be required for further testing of the functional significance of specific genetic alterations as they are identified. In addition models of prostatic disease are necessary to evaluate novel therapeutic approaches. METHODS: The mouse prostate reconstitution (MPR) model system was developed more than a decade ago with these specific needs in mind. Over the years, specific modifications of the MPR model have demonstrated its versatility and applicability for the study of benign and malignant prostatic disease, including metastatic progression. RESULTS: We discuss various modifications of the MPR model system made for its application to specific aspects of prostatic disease; the clinically relevant information that has been gleaned thus far from the use of this model system; and advances on the horizon for the expansion of its role in prostate research. CONCLUSIONS: The MPR model system has contributed substantially to the understanding and treatment of benign and malignant prostatic diseases. Additional modifications in this series of in vivo and in vitro models will likely lead to further advances.

Animals↗
PubMed2000

Joys and pitfalls of fermi surface mapping in Bi(2)Sr(2)CaCu(2)O(8+delta) using angle resolved photoemission

On the basis of angle-scanned photoemission data recorded using unpolarized radiation, with high (E,k) resolution, and an extremely dense sampling of k space, we resolve the current controversy regarding the normal state Fermi surface (FS) in Bi(2)Sr(2)CaCu(2)O(8+delta). The true picture is simple, self-consistent, and robust: the FS is holelike, with the form of rounded tubes centered on the corners of the Brillouin zone. Two further types of features are also clearly observed: shadow FSs, which are most likely to be due to short range antiferromagnetic spin correlations, and diffraction replicas of the main FS caused by passage of the photoelectrons through the modulated Bi-O planes.

Journal Article↗
PubMed2000

Induction of human Cdc37 in prostate cancer correlates with the ability of targeted Cdc37 expression to promote prostatic hyperplasia.

The Cdc37 gene encodes a 50 kDa protein which targets intrinsically unstable oncoprotein kinases such as Cdk4, Raf-1, and src to the molecular chaperone Hsp90. This activity is thought to play an important role in the establishment of signaling pathways controlling cell proliferation. The budding yeast Cdc37 homolog is required for cell division and mammalian Cdc37 is expressed in proliferative zones during embryonic development and in adult tissues, consistent with a positive role in proliferation. Here we report that human prostatic tumors, neoplasias and certain pre-malignant lesions display increased Cdc37 expression, suggesting an important and early role for Cdc37 in prostatic transformation. To test the consequences of increased Cdc37 levels, transgenic mice expressing Cdc37 in the prostate were generated. These mice displayed a wide range of growth-related abnormalities including prostatic epithelial cell hyperplasia and dysplasia. These data suggest that the expression of Cdc37 may promote inappropriate proliferation and may be an important early step in the development of human prostate cancer.

Animals↗
PubMed2000

Signals from trunk paraxial mesoderm induce pronephros formation in chick intermediate mesoderm.

We used Pax-2 mRNA expression and Lim 1/2 antibody staining as markers for the conversion of chick intermediate mesoderm (IM) to pronephric tissue and Lmx-1 mRNA expression as a marker for mesonephros. Pronephric markers were strongly expressed caudal to the fifth somite by stage 9. To determine whether the pronephros was induced by adjacent tissues and, if so, to identify the inducing tissues and the timing of induction, we microsurgically dissected one side of chick embryos developing in culture and then incubated them for up to 3 days. The undisturbed contralateral side served as a control. Most embryos cut parallel to the rostrocaudal axis between the trunk paraxial mesoderm and IM before stage 8 developed a pronephros on the control side only. Embryos manipulated after stage 9 developed pronephric structures on both sides, but the caudal pronephric extension was attenuated on the cut side. These results suggest that a medial signal is required for pronephric development and show that the signal is propagated in a rostral to caudal sequence. In manipulated embryos cultured for 3 days in ovo, the mesonephros as well as the pronephros failed to develop on the experimental side. In contrast, embryos cut between the notochord and the trunk paraxial mesoderm formed pronephric structures on both sides, regardless of the stage at which the operation was performed, indicating that the signal arises from the paraxial mesoderm (PM) and not from axial mesoderm. This cut also served as a control for cuts between the PM and the IM and showed that signaling itself was blocked in the former experiments, not the migration of pronephric or mesonephric precursor cells from the primitive streak. Additional control experiments ruled out the need for signals from lateral plate mesoderm, ectoderm, or endoderm. To determine whether the trunk paraxial mesoderm caudal to the fifth somite maintains its inductive capacity in the absence of contact with more rostral tissue, embryos were transected. Those transected below the prospective level of the fifth somite expressed Pax-2 in both the rostral and the caudal isolates, whereas embryos transected rostral to this level expressed Pax-2 in the caudal isolate only. Thus, a rostral signal is not required to establish the normal pattern of Pax-2 expression and pronephros formation. To determine whether paraxial mesoderm is sufficient for pronephros induction, stage 7 or earlier chick lateral plate mesoderm was cocultured with caudal stage 8 or 9 quail somites in collagen gels. Pax-2 was expressed in chick tissues in 21 of 25 embryos. Isochronic transplantation of stage 4 or 5 quail node into caudal chick primitive streak resulted in the generation of ectopic somites. These somites induced ectopic pronephroi in lateral plate mesoderm, and the IM that received signals from both native and ectopic somites formed enlarged pronephroi with increased Pax-2 expression. We conclude that signals from a localized region of the trunk paraxial mesoderm are both required and sufficient for the induction of the pronephros from the chick IM. Studies to identify the molecular nature of the induction are in progress.

Animals↗
PubMed2000

The action of soybean lipoxygenase-1 on 12-iodo-cis-9-octadecenoic acid: the importance of C11-H bond breaking.

Previous work has demonstrated that the ferric form of soybean lipoxygenase-1 will catalyze an elimination reaction on 12-iodo-cis-9-octadecenoic acid (12-IODE) to produce 9, 11-octadecadienoic acid and iodide ion. Elimination is accompanied by irreversible inactivation of the enzyme on 1 out of 10 turnovers. In the present work, 11,11-dideuterio-12-IODE (D(2)-12-IODE) was synthesized and used to demonstrate that both the elimination reaction and inactivation of the enzyme exhibit very large kinetic isotope effects. The rates with the deuterated compound are so low that the isotope effects are difficult to quantify, but they appear to be comparable to the isotope effects previously observed for the normal reaction catalyzed by lipoxygenase and much larger than can be explained by zero-point energy considerations. ESR spectroscopy was used to demonstrate that 12-IODE can reduce ferric lipoxygenase to the ferrous form, and a large isotope effect on this process was observed with D(2)-12-IODE. It is proposed that the pathway leading to reduction and inactivation by 12-IODE is initiated by homolytic cleavage of the C(11)-H bond. Elimination could be initiated either by homolytic or by heterolytic cleavage of this bond. The results suggest that very large isotope effects may be a general feature of C-H bond cleavages catalyzed by this enzyme.

Deuterium↗
PubMed2000

knot is required for the hypopharyngeal lobe and its derivatives in the Drosophila embryo.

The genetic control of segmentation in the Drosophila larval head has been only partially elucidated. We report that the knot (kn) gene of Drosophila is required for the formation of the hypopharyngeal lobe in the germ-band stage embryo and the ventral arms and lateralgräte of the larval head skeleton. Rearrangement mutations of knot disrupt the previously characterized gene, collier, which encodes a COE-family transcription factor. kn is required for the activation of cnc (cap'n'collar, a bZIP homeotic selector gene) in the progenitors of hypopharyngeal lobe. kn is also required for the activation of an EST marker for the cephalic mesoderm, CK01299. Based on the relative expression of kn and the posterior compartment-specific gene hedgehog, we provide additional evidence that in Drosophila, unlike many other insects, the hypopharyngeal lobe arises from part of the mandibular segment.

Animals↗
PubMed2000

[Weights in Horvitz-Thompson statistic for complex samples].

The problem of using ordinary statistical methods basically for simple random samples in analyzing data from complex surveys for non-simple random samples was discussed. Horvitz-Thompson statistic and the poststratification weights were introduced. Illustrative examples were given to show the validity and superiority of Horvitz-Thompson statistic in comparison with statistic used for simple random samples.

Bias↗
PubMed2000

Solid-state synthesis and mechanical unfolding of polymers of T4 lysozyme.

Recent advances in single molecule manipulation methods offer a novel approach to investigating the protein folding problem. These studies usually are done on molecules that are naturally organized as linear arrays of globular domains. To extend these techniques to study proteins that normally exist as monomers, we have developed a method of synthesizing polymers of protein molecules in the solid state. By introducing cysteines at locations where bacteriophage T4 lysozyme molecules contact each other in a crystal and taking advantage of the alignment provided by the lattice, we have obtained polymers of defined polarity up to 25 molecules long that retain enzymatic activity. These polymers then were manipulated mechanically by using a modified scanning force microscope to characterize the force-induced reversible unfolding of the individual lysozyme molecules. This approach should be general and adaptable to many other proteins with known crystal structures. For T4 lysozyme, the force required to unfold the monomers was 64 +/- 16 pN at the pulling speed used. Refolding occurred within 1 sec of relaxation with an efficiency close to 100%. Analysis of the force versus extension curves suggests that the mechanical unfolding transition follows a two-state model. The unfolding forces determined in 1 M guanidine hydrochloride indicate that in these conditions the activation barrier for unfolding is reduced by 2 kcal/mol.

Bacteriophage T4↗
PubMed2000

Regulation of apoptosis in prostatic disease.

BACKGROUND: Recent studies suggest that aberrant regulation of apoptosis, including acquired apoptosis resistance, contributes to perturbations in cell growth that, in part, underlie the development of benign prostatic hyperplasia (BPH) and prostate cancer. Importantly, apoptosis resistance can enhance the malignant properties of prostate cancer cells, contributing to their widespread metastatic activities. Since apoptosis resistance likely contributes to benign and malignant prostate disease, the promotion of apoptosis represents a reasonable therapeutic objective. METHODS: This brief review focuses on the role of apoptosis in prostatic disease and discusses potential intervention points for novel therapeutics. CONCLUSIONS: Novel therapies for prostatic disease, including gene therapy and biological therapy that involve apoptosis as a mechanism of action, are being developed and tested. Ultimately, the identification of proapoptotic and antiapoptotic genes and the pathways through which they operate will serve to provide more rational approaches for further development of more efficacious therapeutic strategies for benign and malignant prostatic disease.

Apoptosis↗
PubMed2000

Effects of prostaglandins and leukotrienes on hypoxic pulmonary vasoconstriction in rats.

To investigate the effects of prostaglandins (PGs) and leukotrienes (LTs) on hypoxic pulmonary vasoconstriction (HPV), in vivo rats experiment and in vitro perfused lung experiment were conducted. The effect of hypoxia on hemodynamics, concentrations of TXB2 and 6-keto-PGF1 alpha in serum and lung tissue during hypoxia and effects of PGs and LTs on HPV were observed. The results showed that pulmonary arterial pressure (Ppa) and pulmonary vascular resistance were increased during hypoxia, but cardiac output and systemic arterial pressure were decreased. There were increases of the concentrations of TXB2 and 6-keto-PGF1 alpha and their ratio in serum and lung tissue during hypoxia. After use of cyclooxygenase inhibitor (indomethacin) in vivo and in vitro, HPV was augmented respectively, but after use of lipoxygenase inhibitor (diethylcorbamazine) or leukotriene receptor blocker (LY-171883), HPV was attenuated. It was suggested that LTs mediated pulmonary vasoconstriction, PGs inhibited pulmonary vasoconstriction and they played a modulating role during hypoxia.

6-Ketoprostaglandin F1 alpha↗
PubMed2000

Expression of p53 and p21 protein in transitional mucosa adjacent to rectal carcinoma and its clinical implication.

To study the biopathological characteristics of the transitional mucosa adjacent to rectal carcinoma, 34 cases were subjected to mucin histochemical and immunohistochemical study to observe the expression of p53 and p21 protein in distal mucosa adjacent to rectal carcinoma and its relationship to the mucin change. The expression of p53 protein was found in 29.4% (10/34) of distal transitional mucosa in the cytoplasm of goblet cells, and its positive staining was within 4 cm from carcinoma margin. All p53 positive mucosa was transitional mucosa. Overexpression of p21 protein was found in 26.5% (9/34) of distal transitional mucosa in cytoplasm of crypt cells, and its positive staining was within 2 cm from carcinoma margin. There was no relationship between the expression of p53 and p21 protein in carcinoma and that in transitional mucosa (P > 0.05). These findings indicated that there was aberrant alteration of p53 and p21 genes in transitional mucosa adjacent to colorectal carcinoma, which provided further evidence that transitional mucosa was an unstable pre-cancerous change. The aberrant mucin change and genetic alteration in distal mucosa of rectal cancer is within 4 cm.

Adenocarcinoma↗
PubMed2000

Effects of L-tetrahydropalmatine on neuron apoptosis during acute cerebral ischemia-reperfusion of rats.

To investigate the effects of L-Tetrahydropalmatine (L-THP) on neuron apoptosis during acute cerebral ischemia-reperfusion of rats and explore the effects of heat shock protein (HSP) on neuron apoptosis, Wistar rats were randomly divided into 3 groups: normal group, ischemia-reperfusion group and treatment group. The condition of neuron apoptosis, the survival state of neuron, pathological changes under an electron microscope and the number of HSP70 positive cells were measured in all groups. Results showed that the apoptosis neuron number was increased obviously at the 24th h during reperfusion and was further increased at the 48th h, the 72th h. While the number of survival neurons was decreased gradually with the prolongation of reperfusion time. Treatment with L-THP could decrease the apoptosis neuron number but increase the survival neuron number and the HSP70 positive cell number. Our study suggested that L-THP could decrease apoptosis and necrosis of neuron, up-regulate the expression of HSP70 and protect the cerebral ischemic injury.

Animals↗