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Biomedical subjects

K Zhang

Publications and source records attributed to K Zhang.

At least 127 records · Page 7Linked to original sources

Clinical spectrum of chromosome 6-linked autosomal dominant drusen and macular degeneration.

PURPOSE: To describe the clinical phenotype and the intrafamilial variation in retinal findings in a North American family with an autosomal dominant drusen disorder that maps to chromosome 6q14. METHODS: Ophthalmic examinations were carried out on participating family members. Fundus photographs were obtained whenever possible. Electroretinography was performed on the proband and her father. Blood was drawn for DNA analysis. RESULTS: Twelve family members had drusen and/or atrophic macular degeneration. The disease in asymptomatic young adults is characterized by fine drusen that are most conspicuous in the macula. The proband presented at 3 years of age with atrophic maculopathy and drusen. Her cousin was found to have atrophic macular lesions and drusen in the first year of life. Two older affected individuals have reduced vision from cicatricial and atrophic macular changes. The gene for the disease was mapped to chromosome 6q14 and appears to be adjacent to but distinct from the locus for North Carolina macular dystrophy. CONCLUSIONS: There is extreme variability in the clinical expression of this dominant form of drusen and macular degeneration. Most young adults have fine macular drusen and good vision. Affected infants and children may have congenital atrophic maculopathy and drusen. There is historical evidence of progression of the disease in late adulthood with moderate visual loss.

Adolescent↗

A new locus for dominant drusen and macular degeneration maps to chromosome 6q14.

PURPOSE: To report the localization of a gene causing drusen and macular degeneration in a previously undescribed North American family. METHODS: Genetic mapping studies were performed using linkage analysis in a single family with drusen and atrophic macular degeneration. RESULTS: The clinical manifestations in this family ranged from fine macular drusen in asymptomatic middle-aged individuals to atrophic macular lesions in two children and two elderly patients. We mapped the gene to chromosome 6q14 between markers D6S2258 and D6S1644. CONCLUSIONS: In a family with autosomal dominant drusen and atrophic macular degeneration, the gene maps to a 3.2-cM region on chromosome 6q14. This locus appears to be distinct from, but adjacent to, the loci for cone-rod dystrophy 7 (CORD7) and North Carolina macular dystrophy (MCDR1). Future identification of the gene responsible for the disease in this family will provide a better understanding of macular degeneration.

Adolescent↗

Heme structure and orientation in single monolayers of cytochrome c on polar and nonpolar soft surfaces.

Polarized x-ray absorption fine structure (XAFS) spectroscopy has been performed in fluorescence mode under total external reflection conditions on frozen hydrated single monolayers of yeast cytochrome c (YCC). The protein molecules were vectorially oriented within the monolayer by tethering their naturally occurring and unique surface cysteine residues to the sulfhydryl-endgroups at the surface of a mixed organic self-assembled monolayer, itself covalently attached to an ultrapure silicon wafer. The sulfhydryl-endgroups were isolated by dilution with either methyl- or hydroxyl-endgroups, producing macroscopically nonpolar or uncharged-polar soft surfaces, respectively. Independent information on the heme-plane orientation relative to the monolayer plane was obtained experimentally via optical linear dichroism. The polarized XAFS data have been analyzed both qualitatively and by a global mapping approach limited to systematically altering the various iron-ligand distances within a model for the local atomic environment of the heme prosthetic group, and comparing the theoretically generated XAFS spectra with those obtained experimentally. A similar analysis of unpolarized XAFS data from a frozen solution of YCC was performed using either the heme environment from the NMR solution or the x-ray crystallographic data for YCC as the model structure. All resulting iron-ligand distances were then used in molecular dynamics (MD) computer simulations of YCC in these three systems to investigate the possible effects of anisotropic ligand motions on the fits of the calculated to the experimental XAFS spectra.

Absorptiometry, Photon↗

The novel human IgE epsilon heavy chain, epsilon tailpiece, is present in plasma as part of a covalent complex.

Several splice variants of the secreted human epsilon heavy chain have previously been identified by reverse transcription-PCR. The heavy chain of one isoform, IgE tailpiece, differs from the originally identified IgE, IgE classic, by the replacement of the 2 carboxy-terminal amino acids by 8 novel amino acids including a carboxy-terminal cysteine residue. Recombinant human epsilon tailpiece and epsilon classic heavy chains were expressed and secreted as H2L2 monomers in Sp2/0 murine myeloma cells. We have investigated the in vitro function and in vivo occurrence of epsilon tailpiece heavy chains using receptor binding assays, granule release assays, flow cytometry, half-life studies, immunoprecipitation, SDS-PAGE, two-dimensional SDS-PAGE, and Western blotting. IgE tailpiece and IgE classic exhibited similar in vivo half-lives in BALB/c mice, bound the human high- and low-affinity IgE receptors with similar affinities and triggered equivalent levels of high affinity IgE receptor induced degranulation. In humans, IgE classic is present as a 190 kD circulating protein in vivo. In contrast, we found that in plasma epsilon tailpiece was primarily present as part of covalent complexes of approximately 300 and 338 kD. Dissociation of the complexes revealed that two species of epsilon tailpiece heavy chains were present therein and surprisingly, these in vivo derived epsilon tailpiece heavy chains were approximately 5 and 10 kD smaller than the recombinant expressed epsilon tailpiece or epsilon classic heavy chains. These results show that epsilon tailpiece is present in novel covalent complexes in humans.

Animals↗

Dopamine D(4) receptors in rat forebrain: unchanged with amphetamine-induced behavioral sensitization.

Dopamine D(2) receptors are implicated in stimulant-induced behavioral sensitization.(7,10) Studies using selective receptor antagonists also implicate the D(4) receptor, a member of the dopamine D(2)-like receptor family.(3) Accordingly, dopamine D(4) and D(2)-like receptor levels in rat forebrain were examined by computed autoradiography after repeated (+)-amphetamine treatment that induced behavioral sensitization. Receptor binding was quantified in critical brain regions including caudate-putamen, nucleus accumbens septi, medial prefrontal cortex and hippocampus. No significant differences in D(4) or D(2)-like receptor levels were detected among rats sensitized to amphetamine, those exposed to amphetamine but killed before behavioral sensitization emerged or vehicle-treated controls. The findings indicate that expression of amphetamine-induced behavioral sensitization is not associated with altered D(4) (or D(2)) receptor density in rat forebrain.

Amphetamine↗

GABA(B) receptors: altered coupling to G-proteins in rats sensitized to amphetamine.

Modified dopamine and glutamate neurotransmission in discrete brain regions is implicated in stimulant-induced behavioral sensitization. Release of both neurotransmitters is influenced by GABA(B) metabotropic receptors for the principal inhibitory neurotransmitter GABA. Accordingly, GABA(B) receptors were examined in rats sensitized to amphetamine by measuring receptor density and coupling to G-proteins indicated as [(3)H]baclofen binding and baclofen-mediated [(35)S]GTP gamma S binding. Repeated treatment with (+)-amphetamine (5mg/kg per day, i.p., for five days) sensitized the rats to amphetamine challenge (1mg/kg) at 14 days, but not one day, later. GABA(B) receptor density was not altered at either time. Baclofen-mediated [(35)S]GTP gamma S binding, however, was selectively augmented in the prefrontal cortex and attenuated in the nucleus accumbens at 14 days, but not one day, after amphetamine treatment. Changes in GABA(B) receptor coupling to G-proteins in rats sensitized to amphetamine, but not in similarly treated but unsensitized rats, lead us to suggest that altered GABA(B) receptor functioning may contribute to the expression of amphetamine-induced behavioral sensitization.

Amphetamine↗

Eicosapentaenoic acid suppresses PDGF-induced DNA synthesis in rat mesangial cells: involvement of thromboxane A2.

BACKGROUND: The administration of eicosapentaenoic acid (EPA) derived from marine oils has been shown to suppress vascular myocyte, lymphocyte, keratinocyte, and mesangial cell proliferation in vitro, although the effects are variable and most reports provide fragmented insight into the mechanism(s) responsible for altering cell growth, particularly the relationship of membrane lipid remodeling to changes in cell proliferation. Thus, these studies were designed to elucidate the effects of mesangial cell membrane fatty acid remodeling (induced by EPA) on cell growth, and to define the relevance of changes in the synthesis of growth-modulating eicosanoids. METHODS: Mesangial cells were grown in RPMI and 17% fetal calf serum, and were subcultured and grown for 48 hours in 17% delipidated serum or delipidated serum supplemented with 0 to 50 micrograms/mL of EPA. Quiescent EPA-loaded and control mesangial cells were subjected to stimulation with 20 ng/mL of platelet-derived growth factor (PDGF) followed by measurement of 3H-thymidine incorporation and cell number. RESULTS: Mesangial cells remodeled with EPA exhibited a significant decrease in PDGF-stimulated 3H-thymidine incorporation and cell number associated with a reduction in thromboxane A2 (TXA2) in the media. Importantly, the phospholipid fatty acid composition of mesangial cells grown in media enriched with EPA revealed an increase in EPA (0.5 +/- 0.02% to 17.02 +/- 0.52%) coupled with a reciprocal decrease in the precursor for TXA2, arachidonic acid (18.9 +/- 3.17% to 3.55 +/- 0.30%). Blockade of TXA2 synthesis in mesangial cells treated with indomethacin (0.1 to 100 mumol/L) or the specific TXA2 synthase inhibitor, U-63557A (0.1 to 100 mumol/L), evoked a similar reduction in PDGF-stimulated proliferation and TXA2 synthesis. Coincubation of PDGF with the TXA2 mimetic, U-46619 (1 mumol/L), reversed the growth suppression induced by cell membrane remodeling. CONCLUSIONS: These studies suggest that changes in membrane fatty acid composition induced by EPA modulates PDGF-stimulated proliferation by engendering a change in PDGF-stimulated TXA2 synthesis. Furthermore, we conclude that TXA2 functions as a comitogen for PDGF-stimulated mesangial cell growth.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

Genetic and molecular mechanisms of age regulation (homeostasis) of blood coagulation.

Blood coagulation plays a critical role not only in hemostasis but also in many physiological and pathological conditions. Epidemiological studies have shown that blood coagulation capacity in humans increases with age. Towards understanding the underlying mechanisms, the age regulation of factor IX, a key blood coagulation factor, was extensively studied. A series of human factor IX minigenes, consisting of various components of the human factor IX gene, were constructed and subjected to systematic analyses with HepG2 cells in culture and over the entire life span of transgenic mice. These studies identified critical gene structures that are essential for the unique age-dependent expression patterns of the human factor IX gene--one acting by stabilizing gene transcription and another increasing the amount of mRNA present, presumably by augmenting mRNA stability. These studies have set the stage for analyzing the overall age-based regulatory mechanisms of blood coagulation.

Age Factors↗

Norepinephrine turnover in peripheral tissues of rats with heart failure.

Experiments were performed to determine if there is regional heterogeneity in sympathetic neural activation of peripheral tissues in rats with chronic heart failure (HF; 6-8 wk after coronary artery ligation). Norepinephrine (NE) turnover, an index of sympathetic activation, was determined on the basis of the decline in tissue NE levels that occurs during the 8-h after tyrosine hydroxylase inhibition (alpha-methyl-DL-p-tyrosine, 300 mg/kg ip at 4-h intervals). Compared with sham-operated rats, NE turnover was increased in the cardiac left ventricle, skeletal muscle, duodenum, and kidney of rats with HF, but was unaltered in liver and spleen. The increased renal NE turnover in HF was largely a reflection of increased turnover in the cortex, with no change evident in the medulla. Blockade of sympathetic ganglionic traffic (hexamethonium, 2 mg/kg sc at 2-h intervals) eliminated the tissue-specific effects of HF on tissue NE levels measured 8-h after tyrosine hydroxylase inhibition. These data support the contention that chronic HF evokes a central nervous system-mediated increase in basal sympathetic tone that exhibits regional heterogeneity (both between and within organs), a phenomenon that likely contributes to the functional consequences of this pathophysiological state.

Animals↗

[Bacterial genetic diversity in soils and their correlation with vegetation].

Soil is an important epicenter of biodiversity. Human activity has threatened such biodiversity through vegetation shift. As the major type of microbes, bacteria have played key roles in material cycling. Since simple morphological characters and the failure of the major portion of bacteria in surviving artificial cultivation have hindered bacterial diversity from analyses using traditional taxonomic approaches, bacterial diversity and its correlation with vegetation is less understood. In order to detour cultivation, tag serial sequencing strategy was developed in this study, in which a 26 base pair highly variable region has been chosen from 16S ribosomal RNA gene as variant-representing tags, ligated into serials and sequenced. Molecular bacterial diversity in soils has been determined using tag types, tag frequencies and diversity index as parameters. The correlation of bacterial diversity with vegetation has been explored as well. Bacterial diversity and differentiation correlate highly with contents of organic matter and nitrogen of soils and further vegetation.

Bacteria↗

[Study of differential expressed genes in vascular endothelial cell line ECV304 induced by low density lipoprotein].

OBJECTIVE: To isolate and clone the differential expressed genes induced by atherogenic factors on vascular endothelium and to understand the molecular mechanism of atherosclerosis. METHODS: The differential display reverse transcription PCR method (DDRT-PCR) was used to analyze the differential expressed cDNA in ECV304 induced by low density lipoprotein (LDL). After sequencing and homology research, the differential expressed cDNA fragments were confirmed by northern blot analysis. RESULTS: Up-regulated and down-regulated cDNAs fragments were isolated in ECV304. It was found that some cDNAs fragments were highly homologous to the known human genes, while others were fragments of novel genes. The known up-regulated genes included human 10 kD protein, FGFR1 oncogene partner, intercellular adhesion molecular-1, FK506 binding protein and rTS beta genes. The known down-regulated genes included human fb19, Apobec1-binding protein 1 and RBP2. The expression levels of different genes varied by 70%-200%. CONCLUSION: By DDRT-PCR method, our results showed that LDL could change the expression of many genes in endothelial cells. The high expression level of ICAM-1 in the endothelial cells stimulated by LDL suggested that ICAM-1 is an important adhesion molecular in atherogenesis. The down-regulated expression of Apobec 1-binding protein 1 may affect the cellular synthesis of apolipoprotein. The high expression level of FGFR1 oncogene partner is likely related to the differentiation of ECV304. The function of other differential expressed genes remains to be elucidated.

Cells, Cultured↗

[Applied anatomy of arterial supply for the soft palate].

OBJECTIVE: The correct design of a myomucosal or mucosal flap of the soft palate in the surgical procedure for cleft palate and velopharyngeal incompetence should be made with a thorough knowledge of the arterial supply for the soft palate, which is an important premise for functional rehabilitation of the soft palate postoperatively. METHODS: Anatomical dissection was undertaken in 14 cadavers (10 normal adults, 2 normal newborns and 2 newborns with cleft lip & palate). The arteriography and histological studies have been used in 10 newborn and 6 aborted fetuses. RESULTS: The results showed that the arterial supply of the soft palate is multi-original and the principal artery is the ascending palatal artery. Its anterior and posterior branches are myomucosal perforators. The other vessels to supply the soft palate are direct mucosal branches, which include the lesser palatine artery, the palatal branch of the ascending pharyngeal artery and the tonsillar artery. All above arteries anastomose under the mucosal, muscular and fascial layers in the soft palate. In cleft cases, all arteries in the soft palate are displaced anterior-laterally because of the deformities of the palatal muscles and bone structure. CONCLUSIONS: This study supports the facts that the major blood supply of the soft palate comes from ascending palatine artery and the generous arterial anastomosis of the velum allows it to tolerate the proper dissection during palatoplasty. We believe that decreasing the damage of the intrapalatal vascular supply by carefully dissection around the hamulus is very important to prevent wound break down, muscular fibrosis, flap failure, and also is the basis of design for surgical procedure and postoperative functional recovery in cleft palate patients.

Adult↗

[Horizontal thermal characteristics at forest edge in calm tropical region of China].

The temperature measurement at southwest-facing edge of a rubber forest was conducted in a calm tropical region of Xishuangbanna, Yunnan, China in January 1998, and the daytime thermal characteristics and their time-space variations nearby the edge of the rubber forest were discussed. There was an obviously thermal effect at forest edge. The depth of edge influence on soil surface temperature was up to 13 m from the edge into the forest. Soil surface temperature reached its highest at 4.5 m outside the forest. The highest air temperature occurred at 0 m of the edge. The heat transfer nearby the edge was quite different in number and in direction. Outside the forest, the heat was transferred from ground to air on almost daytime, while at interior of forest, was opposite after the noon. The heat was transferred from the rubber canopy to the ground. At the forest edge, such variation was complex, depended mainly on location and time.

China↗

Asymmetry of brain functional activation: fMRI study under language and music stimulation.

OBJECTIVE: To determine the asymmetry of the human brain functional activation. METHODS: With the help of GE Signa Horizon MRI system, 14 cases of right-handed volunteers were examined and the blood oxygenation level dependent method was used. The T1-weighted images were obtained with spin echo pulse sequence and the functional imaging (T2*-weighted) was performed using a single shot echo planar imaging pulse sequence. Data analysis was done with Sun Sparc Workstation and by the method of student t test or correlation analysis. RESULTS: Most of activation areas were in the left hemisphere under language stimulation, while they were in the right side under music stimulation. Besides, a few brain areas in the contralateral cerebral cortex were also activated under both stimulations. CONCLUSION: The present study supported the hypothesis of the asymmetry of brain functional activation and many brain areas of the cerebral cortex as well as both hemispheres worked in coordination. In addition, it also proved that fMRI is a feasible method in the study of human brain in vivo.

Acoustic Stimulation↗

[Field epidemiological and experimental study on relationship between genetic factor and nonresponse or hyporesponse to hepatitis B vaccine].

OBJECTIVE: To evaluate the role of genetic factor in the development of nonresponder or hyporesponder to hepatitis B vaccine in Chinese people from field epidemiology and experimental study. METHODS: Six hundred and thirty-four susceptible healthy students were vaccinated with three doses of plasma-derived hepatitis B vaccine. Twenty-nine non- or hypo-responders (subjects) and 30 hyperresponders (controls) as well as their 80 and 79 first degree relatives were determined and recruited in the study. The first degree relatives of subjects and controls were then immunized with hepatitis B vaccine and followed up. On the basis of the above results, alleles of HLA-A, B, C, DR and DQ locus were further detected in the two groups. RESULTS: The non- and hypo-response rate in immunized students was 4.6% (29/634). After administered with hepatitis B vaccine, the first degree relatives of the subjects displayed a 17.9% frequency of nonresponsiveness, higher than in the controls. The phenotype frequency of HLA-DR7 and B54 was 52.2% and 21.7% in subjects, 9.1% and 0.0% higher than in controls, respectively. The extended haplotype B54-DR7 was more frequent in the former (17.0%) than in the latter (0.0%) (P < 0.01). CONCLUSION: These results demonstrated that the genetic factor was likely associated with the non- and hypo-response to hepatitis B vaccine in Chinese people.

Adolescent↗

[Pleural effusion of gout].

OBJECTIVE: To investigate the lung complication of patients with gout. METHODS: Laboratory, radiation and pathology examining were exerted to 11 patients with gout and lung injury. RESULTS: Uric acid crystal was found in four patients pleural effusion and stones in two patients' spittle which were consist of monosodium urate (MSU). Uric acid salt crystal was found sputum in five patients as well as fibrosis was found in the patients' lung by radiation and pathology examination. CONCLUSIONS: The diagnoses of lung complications in eleven patients with gout were reliable.

Adult↗

[The relationship among proinsulin and true insulin to coronary artery disease].

OBJECTIVE: Whether proinsulin (PI) and true insulin (TI) are independently related to coronary artery disease (CAD). METHODS: 54 patients with CAD diagnosed by coronary angiography and/or intravascular ultrasound, 37 patients without CAD by coronary angiography and/or intravascular ultrasound and 23 healthy volunteers. All subjects had oral glucose tolerance test after an overnight 14 h fast. PI and TI concentrations were detected at different phases by BA-ELISA in which PI cross -reactivity is less than 0.1%. RESULTS: Fasting and post-glucose loading PI and TI levels in both CAD and non-CAD groups significantly increased when compared with the control group (P < 0.05), after adjustment for age, body mass index and waist hip ratio, all statistically significant associations weakened or disappeared among three groups; but there was no significant difference of all the above variables between CAD group and non-CAD group (P > 0.05). CONCLUSION: PI and TI, whether fasting or post-glucose loading, may not be independently related to CAD.

Adult↗

[Clinical value of fetal monitoring in intrahepatic cholestasis of pregnancy].

OBJECTIVE: To study the clinical value of fetal monitoring in intrahepatic cholestasis of pregnancy (ICP). METHODS: Two hundred and six cases of ICP, delivering in our hospital from Dec. 1993 to Sept. 1998 were investigated. In these cases, 206 cases were examined by the fetal monitoring and vibratory acoustic stimulation test (VAS-T), 157 cases by ultrasonic umbilical artery flow analysis, and 127 cases by fetal electrocardiograph (FECG). RESULTS: There is a significant difference between normal and abnormal groups of the poor perinatal prognosis in contraction stress test (CST) and oxytocin challenge test (OCT) and ultrasonic umbilical artery flow analysis (P < 0.005, P < 0.05). There is no difference between normal and abnormal groups of the poor perinatal prognosis in NST, VAS-T and FECG. CONCLUSION: CST, OCT and ultrasonic umbilical artery flow analysis have the higher clinical value to detect the poor placental function and to foretell the perinatal prognosis in ICP.

Adult↗