Neutron halos in O isotopes.
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Journal Article↗
Biomedical subjects
Z Ren
Publications and source records attributed to Z Ren.
Expression of platelet-derived growth factor beta receptor in chondrogenesis of perichondrial transplants.
An experimental study was done in two rabbits to establish whether the early stages of cartilage generation involves stimulation via the platelet-derived growth factor beta receptor (PDGFR-beta). Rib perichondrium was dissected off and transplanted to the knee joint. The perichondrial grafts were removed for microscopic investigation at day 0 and day 6 and kept frozen until analysed by immunohistochemistry and in situ hybridisation for the presence of PDGF beta receptor protein and mRNA, respectively. Samples from day 0 showed sparse cells with a positive immunohistochemical reaction. In samples from day 6 there were signs of perichondrial proliferation and chondroid maturation and a more widespread immunohistochemical staining reaction could be seen mainly on proliferating perichondrial cells, but also on some chondrocytes. In situ hybridisation confirmed the expression of PDGF beta receptor mRNA in the same areas of serial sections. These findings may indicate that PDGF beta receptor activity is part of the early response after autotransplantation of perichondrium.
Animals↗
[Fibrous structure of connective tissue of normal human lamina cribrosa].
Fibrous components and structural morphology of the connective tissue of the lamina cribrosa obtained from 35 normal human autopsy eyes were examined by histochemical staining, transmission electron microscopic and computer-assistant image analytical techniques. Principles of biomechanics were used onto the lamina cribrosa in characterizing its structural and mechanical properties, and in investigating its damage forms, intermediary role between intraocular pressure and optic nerve damage, and intervening factors. We came to the following conclusions: The laminar bundles contain all the three kinds of fibers and behave in such triplex properties as elasticity, plasticity and stiffness. The ellipse shaped transverse section of the lamina cribrosa with the long axis at the vertical meridian, the quadrant variations in the course and density of laminar bundles, and the interindividual variations in the thickness of the lamina cribrosa are responsible for the damage-resistant ability of lamina cribrosa. The intraocular pressure exerts effects upon the lamina cribrosa through two ways, and the damage of the lamina cribrosa is the intermediate link between the insults of the intraocular pressure and the optic nerve damage.
Adult↗
The crystal structure of deshexapeptide (B25-B30) insulin at 0.25 nm resolution.
The determination of deshexapeptide (B25-B30) insulin (DHI) was divided into two steps. At the first step, the rough structure model of DHI molecule was determined by using the molecular replacement method associated with the molecular close-packing method at 0.30 nm resolution based on the reflection data collected on four-cycle diffractometer. At the second step, the DHI model was adjusted and refined at 0.25 nm resolution based on the data collected on Area Detector. 40 water molecules were determined during the refinement, the final R-factor is 0.185 with R.M.S. deviation of 0.002 nm for bond lengths and 1.9 degrees for bond angles. The differences in conformation and function of DHI with other insulin analogues were compared and discussed.
Insulin↗
[Surgical treatment of familial acromegaly].
The annual incidence of the acromegaly is three cases per million, and that of the familial acromegaly is even far rarer. The number of familial acromegaly reported in the medical literature of all the world is fewer than 10 cases per year, and up till now none of such a patient has been reported in China. All the three cases of familial acromegaly reported here were from the same family, and showed typical clinical manifestations. They presented the history of acral enlargement, headache, amenorrhoea, elevated serum GH level, enlargement and erosion of pituitary fossa in X-ray and CT scan, and characteristic immunohistochemical findings of GH-secreting pituitary adenoma. All of them underwent successful transsphynoidal total removal of the pituitary adenoma, and recovered well by clinical, endocrine, and pathological criteria. An extended family tree of 65 members excluded consanguinous marriage and suggested that the mode of inheritance was irregular autosomal dominant.
Acromegaly↗
[Transsphenoidal microsurgical removal of GH-secreting pituitary adenoma in: a report of 200 cases].
From July 1979 to April 1992, 212 cases of GH-secreting pituitary adenoma were treated transsphenoidally by microsurgical technique, of whom two hundred cases monitored with their GH levels at preoperative and postoperative periods. The majority of cases totally 132 cases were of macroadenoma, and 68 cases were of microadenoma. 138 cases were operated on after April 1986. The cure and remission rate averaged to 72.5%, rising from 44.4% (before 1986) to 80.5% for microadenoma and from 31.4% to 69.1% for macroadenoma due to improvement of technique and accumulation of experience. One patient died of angiocardiopathy suddenly during operation. Mortality rate was 0.5%. The follow-up observation of postoperative GH levels in 52 cases revealed that the GH levels within 2 weeks after operation were the same as in 3-6 months. It is thought that the early GH levels may represent the surgical results. The surgical technique is described and factors influencing the surgical results, prevention and treatment of operative complications are discussed in this paper.
Adenoma, Acidophil↗
Laue crystallography for studying rapid reactions.
Precise quantitation of static and time-resolved Laue diffraction patterns is undeniably more complex than for monochromatic patterns. Recent advances in integration and scaling algorithms demonstrate that, with suitable care in the conduct of the Laue experiment itself, Laue data sets can be obtained which rival the best monochromatic data sets in accuracy and completeness. These algorithms deal in an integrated fashion with the several main problems of Laue diffraction patterns: the elongated spots which arise from mosaic crystals, the spatial overlaps which occur in crowded diffraction patterns, the energy overlaps which arise from the mapping of a central line in reciprocal space onto a single spot in detector space, and wavelength normalization.
Journal Article↗
Structure-activity relationships among monoterpene inhibitors of protein isoprenylation and cell proliferation.
The monoterpene d-limonene inhibits the post-translational isoprenylation of p21ras and other small G proteins, a mechanism that may contribute to its efficacy in the chemoprevention and therapy of chemically induced rodent cancers. In the present study, the relative abilities of 26 limonene-like monoterpenes to inhibit protein isoprenylation and cell proliferation were determined. Many monoterpenes were found to be more potent than limonene as inhibitors of small G protein isoprenylation and cell proliferation. The relative potency of limonene-derived monoterpenes was found to be: monohydroxyl = ester = aldehyde > thiol > acid = diol = epoxide > triol = unsubstituted. All monoterpenes that inhibited protein isoprenylation did so in a selective manner, such that 21-26 kDa proteins were preferentially affected. Perillyl alcohol, one of the most potent terpenes, reduced 21-26 kDa protein isoprenylation to 50% of the control level at a concentration of 1 mM, but had no effect on the isoprenylation of 67, 47 or 17 kDa proteins. In particular, p21ras farnesylation was inhibited 40% by 1 mM perillyl alcohol. At the same concentration, perillyl alcohol completely inhibited the proliferation of human HT-29 colon carcinoma cells. The structure-activity relationships observed among the monoterpene isoprenylation inhibitors support a role for small G proteins in cell proliferation, and suggest that many limonene-derived monoterpenes warrant further investigation as antitumor agents.
3T3 Cells↗
Inhibition of ubiquinone and cholesterol synthesis by the monoterpene perillyl alcohol.
Monoterpenes such as perillyl alcohol have been shown to cause the complete regression of advanced mammary carcinomas. Given the common origin of plant monoterpenes and many important molecules in mammalian mevalonate metabolism pathway, we investigated the effects of the monoterpene perillyl alcohol on mevalonate metabolism. NIH3T3 cells were labeled with [14C]mevalonolactone and lipids were analyzed. Perillyl alcohol inhibited ubiquinone synthesis and blocked the conversion of lathosterol to cholesterol. These two cellular effects of perillyl alcohol may contribute to the antitumor activity of the monoterpenes.
3T3 Cells↗
Weakly bound states of a three-body system.
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Journal Article↗
Epithelial-stromal interactions in basal cell cancer: the PDGF system.
A proposed progenitor cell for basal cell carcinoma is a stem cell located in the bulge of the hair follicle. Previous investigations have shown that basal cell carcinoma has a specific stroma requirement for its growth. Likewise the development of a normal hair follicle requires the inductive force of a specialized structure with condensed mesenchyme that eventually forms the dermal hair papilla. Investigations in mouse embryos also strongly indicate that induction/growth of skin structures is dependent on platelet-derived growth factor (PDGF) alpha-receptor expression in the mesenchyme. We therefore investigated the expression of PDGF A and B chain and PDGF alpha and beta receptors in basal cell carcinoma and in normal skin by immunohistochemistry and in situ hybridization. alpha and beta receptors were found in the specific stroma components of basal cell carcinoma, dermal hair papilla, and sweat glands, but not in the epithelial structures. The A and B chains, on the other hand, were mainly found in basal cell carcinoma cells, in hair matrix, and in sweat gland epithelium. This "appositional" expression of PDGF/PDGF receptor closely resembles that found in epithelial/mesenchymal structures during normal development. The findings also suggest that PDGF receptor expression is one of the characteristics of the specific stroma that is necessary for basal cell carcinoma growth.
Capillaries↗
Monoclonal antibody to the aminotelopeptide of type II collagen: loss of the epitope after stromelysin digestion.
A monoclonal antibody was prepared to the aminotelopeptide of type II collagen after immunization of DBA/1 mice with lathyritic type II collagen and subsequent screening for antibodies that recognize lathyritic but not pepsin-digested type II collagen. One antibody (called 5B2) was identified that recognized a short peptide sequence in the aminotelopeptide of chicken type II collagen but did not recognize other collagen types. Further characterization of the epitope was achieved using a Multipin system and the epitope was localized to a short linear sequence of six amino acids. The antibody recognized type II collagen from a variety of species including man and mouse. The epitope for 5B2 was found to be susceptible to cleavage with recombinant stromelysin without cleavage of the major collagen triple helix. Comparison was made between MAb 5B2 and two other antibodies (called MAb 2B1 and MAb 6B3) that recognize separate epitopes located along the triple helix of the type II collagen molecule.
Amino Acid Sequence↗
[Management of vessel defect in digit replantation].
Many severed digits are complicated with vessel defects and make replantation more difficult. Based on experimental study, we have repaired vessel defect in 207 cases (261 digits) by 12 methods. 240 digits (92%) survived. Experimental and clinical procedure, treatment of choice and related problems are described.
Adolescent↗
[Molecular cloning of the adherence gene cluster from uropathogenic Escherichia coli and preparation of its antisera].
A genomic library of the uropathogenic E. coli J96 was constructed by using cosmid pHC79 as cloning vector. Two positive recombination cosmids which could express the adherence characters were acquired. From both cosmids a EcoRI fragment was subcloned into the vector pACYC184 by shot-gun method. Three colonies were found which exhibited MRHA and production of P Pili. One of them, pCT10/E. coli K-12 P678-54, was about 14.6 kb and was used to prepare the antisera. After absorption with pACYC184/E. coli K-12 P678-54 for three times, the antisera were revealed specific against the adherence gene cluster of uropathogenic E. coli by the SDS-PAGE and Western blotting of the P pilus crude extracts and the hemagglutination inhibition test.
Adhesins, Bacterial↗
Sequence-based analysis of the human p53 gene based on microdissection of tumor biopsy samples.
A procedure for direct sequencing of the human p53 gene based on micro-dissection of frozen tumor tissue stained with methylene blue without prior fixation is described. The approach, which is suitable for large-scale analysis, is based on solid-phase DNA sequencing of amplified genomic DNA and does not involve preparative electrophoresis, precipitations, extractions or centrifugations. Here we show that basal cell carcinoma tissue isolated from human skin can be analyzed in a semiautomated fashion using a robotic workstation and a laser fluorescent electrophoresis unit. The results of analyses of patient material displaying various immunohistochemical staining patterns using a p53-specific antibody are presented.
Base Sequence↗
Mechanisms of brain injury with deep hypothermic circulatory arrest and protective effects of coenzyme Q10.
Sixteen dogs, divided randomly into a control group and coenzyme Q10 group (10mg/kg, intraperitoneally before the operation), underwent deep hypothermic circulatory arrest with cardiopulmonary bypass, as is done clinically. At four time points cerebral cortex and cerebrospinal fluid specimens were collected to study free radical formation, energy metabolism, and ultrastructure. During cardiopulmonary bypass cerebral electron spin resonance spectra and malondialdehyde contents were progressively higher than before bypass, especially at the 60 minutes of circulatory arrest and 30 minutes of reperfusion (p1 < 0.01, p2 < 0.05). In the coenzyme Q10 group at the latter two time points, they had increased less than in the control group at same time points (p1 < 0.02, p2 < 0.005). Adenosine triphosphate content in the cortex during bypass decreased gradually from the prebypass level (p1 < 0.02, p2 = p3 < 0.001), while lactate in cerebrospinal fluid increased (p1 < 0.05, p2 = p3 < 0.001). In the coenzyme Q10 group, adenosine triphosphate at the latter two time points was greater than that in the control group (p1 = p2 < 0.05), while the lactate changes were not significantly different from control at each time point (all p > 0.05). Ultrastructure of the cortex was normal before bypass and almost normal during bypass, but it was obviously abnormal at 60 minutes of circulatory arrest and more seriously abnormal at 30 minutes of reperfusion. In the coenzyme Q10 group the abnormality was obviously reduced. The results suggest that oxygen-derived free radicals and abnormal energy metabolism might play critical roles in brain ischemia/reperfusion injury. Coenzyme Q10 could protect the brain by improving cerebral metabolism.
Adenosine Triphosphate↗
Atomic structure of a cytochrome c' with an unusual ligand-controlled dimer dissociation at 1.8 A resolution.
The crystallographic structure of cytochrome c' from the purple phototrophic bacterium Chromatium vinosum (CVCP) has been determined at 1.8 A resolution using multiple isomorphous replacement. The molecule is a dimer, with each 131-residue chain folding as a four-helical bundle incorporating a covalently bound heme group at the core. This structure is the third of the ubiquitous cytochromes c' to be solved and is similar to the known structures of cytochrome c' from R. molischianum (RMCP) and R. rubrum (RRCP). CVCP is unique in exhibiting ligand-controlled dimer dissociation while RMCP and RRCP do not. The Tyr16 side-chain, which replaced Met16 in RMCP and Leu14 in RRCP, is parallel to the heme plane and located directly above the sixth ligand site of the heme Fe. Any ligand binding to this site, such as CO or CN-, must move the Tyr16 side-chain, which would be expected to cause other conformational changes of helix A, which contributes to the dimer interface, and consequently disrupting the dimer. Thus, the crystallographic structure of CVCP suggests a mechanism for dimer dissociation upon ligand binding. The dimer interface specificity is due to a lock and key shape complementarity of hydrophobic residues and not to any charge complementarity or cross-interface hydrogen bonds as is common in other protein-protein interfaces. The co-ordinates have been deposited in the Brookhaven Data Bank (entry P1BBH).
Amino Acid Sequence↗
Molecular close-packing method and its application to crystal structure determination of deshexapeptide (B25-B30) insulin.
Based on the molecule-packing theory, we defined a molecule-packing function expressing the compatibility of packing among the symmetry-related molecules in a unit cell. A computer program imitating the close-packing of molecules in the objective crystal lattice and giving the function value of each rotation and translation of the molecule in the unit cell was performed, and it therefore made the close-packing of molecules express quantitatively. This method not only could judge a correct solution from several peaks of the rotation or translation function but it may also independently, quantitatively and quickly solve some specific problems of rotation and translation. Using known structure of despentapeptide (B26-B30) insulin as an example, the effectiveness of this method and its program was inspected, and this method was successfully applied to solving the translation problem of the unknown structure of deshexapeptide (B25-B30) insulin. The molecular close-packing method proved by the results of R-search and electron density maps is relatively independent of the molecular replacement method, though an effective complement of it.
Computers↗