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Biomedical subjects

Y Pan

Publications and source records attributed to Y Pan.

At least 217 records · Page 12Linked to original sources
PubMed1994

Deletion mapping of chromosome 8p in prostate cancer by fluorescence in situ hybridization.

Double-target fluorescence in situ hybridization (FISH) was applied to 42 cases of prostate cancer and seven cases of histologically proven benign prostate hyperplasia for the detection of structural aberrations of chromosome 8. Cosmid probes for two chromosome 8p loci (LPL/8p22 and D8S7/8p23) were used in 34 specimens of malignant tumors obtained by the touch biopsy technique. Deletion was defined as when the number of cosmid signals was lower than the number of centromere signals in more than 35% of all nuclei observed. In total, thirty of the 42 (71%) specimens demonstrated any type of 8p deletion. Out of the 34 cases in which deletion mapping could be evaluated, distal deletion (D8S7) was detected in 17 (50%), of which 10 also showed deletion of LPL. Deletion of LPL was detected in 18 cases (53%), of which 8 (24%) retained the D8S7 (interstitial deletion). When the deletion pattern was graded as (1) no deletion (2) partial deletion (either D8S7 or LPL deleted) and (3) both deletions, the degree of deletion was well correlated with the tumor grade (P = 0.0009) and with stage (P = 0.0072, Fisher's Exact test). These data support the hypothesis that tumor suppressor gene(s) may be located in the chromosomal region 8p22, hence 8p deletions may play a crucial role in the pathogenesis of prostate cancer.

Chromosome Deletion↗
PubMed1993

Prenylation of Rab5 is dependent on guanine nucleotide binding.

Rab5 is a small molecular weight GTP-binding protein that functions in endocytic vesicle traffic. Like other Ras-related proteins, Rab5 is prenylated on C-terminal cysteine residues, although it lacks the typical C-terminal CAAX motif (where A is any aliphatic amino acid and X is any amino acid) to direct this post-translational modification. We have investigated structural requirements for the in vitro geranylgeranylation of Rab5. Rab5N133I, a point mutant that has impaired ability to bind GTP or GDP, undergoes modification to a limited extent and at a severely reduced rate when compared to cognate Rab5. A second point mutant, Rab5Q79L, can be processed to approximately the same extent as wild-type albeit at a reduced rate. Since the latter mutation results in defective GTPase activity, these combined observations indicate that guanine nucleotide binding plays an important role in the geranylgeranylation reaction and suggest that the GDP-bound form of Rab5 is the preferred conformation for interaction with Rab prenyltransferase. This idea is supported by the finding that non-hydrolyzable GTP analogs inhibit Rab5 prenylation, while in vitro processing of both H-ras and the gamma 2 subunit of regulatory G proteins is unaffected at concentrations of guanosine 5'-O-(thiotriphosphate) (GTP gamma S) up to 400 microM. Moreover, a truncation mutant lacking the C-terminal cysteines, Rab5(1-211), serves as an inhibitor of Rab5wt geranylgeranylation when liganded with GDP but not GTP gamma S. Thus, the recognition of Rab5 as a substrate by Rab prenyltransferase involves structural elements exclusive of the C terminus and dependent upon the GDP-binding conformation of the protein.

Animals↗
PubMed1993

Cross-links in cell walls of Bacillus subtilis by rotational-echo double-resonance 15N NMR.

The cross-link index of peptidoglycan of intact cell walls of Bacillus subtilis grown in media containing L-[2-13C,15N]aspartic acid has been determined by rotational-echo double-resonance 15N NMR. A cross-link index of 72% decreased to 47% when the bacteria were exposed to the antibiotic cephalosporin C. The fraction of 15N label routed from aspartic acid in the media to glutamic acid in the peptidoglycan peptide stems more than doubled for the cephalosporin-exposed cells, indicating interference with general cell wall nitrogen metabolism by the antibiotic.

Aspartic Acid↗
PubMed1993

Improved method for release of cell nuclei from paraffin-embedded cell material of squamous cell carcinomas.

An improved method of releasing cell nuclei from paraffin-embedded highly keratinized squamous cell carcinomas by pretreatment with 85% formic acid-0.3% H2O2 followed by enzymatic treatment with subtilisin Carlsberg is described. After DAPI staining the resulting suspensions of cell nuclei were analyzed by DNA flow cytometry, in addition to microscopy. The total yield of released cell nuclei was improved and the proportion of tumor cell nuclei in the suspensions increased from 12% to 53% using this method compared to the conventional preparation technique. Cytoplasmic residue disappeared nearly completely. Thus, the finding of false aneuploid cell populations representing diploid cells with autofluorescent cytoplasm could be avoided. In addition, even small true aneuploid cell populations could be detected due to the increased proportion of released tumor cell nuclei and the lower proportion of background in the > 2C region.

Carcinoma, Squamous Cell↗
PubMed1993

Cholinergic-opioid interactions at brainstem respiratory chemosensitive areas in cats.

Central respiratory chemosensitivity has been ascribed to CO2-sensitive neurons located on the ventral brainstem surface. The effects of cholinergic mechanisms on CO2-sensitive neuronal activity recorded extracellularly at the brainstem respiratory chemosensitive area at the caudal ventral medullary surface (cVMS) were investigated in cats (n = 14) anesthetized with chloralose-urethane. The neurons increased their firing rate from 10.4 +/- 1.6 Hz to 33.9 +/- 5.2 Hz when the mock cerebrospinal fluid (mCSF) superfusing buffer solution was changed from pH 7.4 (control) to pH 7.0 (acidic). Atropine (ATR) applied topically to the cVMS depressed the H(+)-ion-induced increase in neuronal frequency from 32.8 +/- 4.8 Hz to 13.4 +/- 2.2 Hz. ATR also depressed the inspired-CO2-induced increase in neuronal activity from 33.2 +/- 8.3 Hz to 18.9 +/- 4.9 Hz, suggesting the possibility of a muscarinic cholinergic involvement in cVMS neuronal responses to changes in PCO2 and mCSF-pH. Acetylcholine (ACh) increased the activity of cVMS CO2-sensitive neurons by 237.5% +/- 34.9%, and naloxone applied topically to the cVMS augmented the ACh responsiveness to 338.6% +/- 52.7%. Physostigmine (PHY) increased neuronal activity by 254.3% +/- 42.9%, and this increase was augmented to 435.4% +/- 61.2% by naloxone. Although responses of the CO2-sensitive neurons to PHY were biphasic, the depressant phase failed to appear whenever the cVMS was pretreated with naloxone. Naloxone also augmented the responsiveness of cVMS neurons to increased H+ ion superfusion. These findings suggest that the endogenous opiates may be involved in the central regulation of respiration by interaction with CO2-sensitive cholinergic structures at the cVMS.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1993

Effects of argipressin injected into medial amygdaloid body on blood pressure and heart rate in rats.

Graded injections of argipressin (Arg, 150, 300, and 600 ng/1.5 microliters CSF, 2 min) into the medial amygdaloid body in anesthetized rats produced a dose-related increase in the mean arterial pressure and heart rate (Maximal delta MAP = 2.9 +/- 1.5 kPa, Maximal delta HR = 67 +/- 38 bpm), which lasting > 40 min at 600 ng dosage. Naloxone (15 micrograms/15 microliters CSF) injected into the lateral ventricle blocked the cardiovascular responses to Arg. These results suggest that Arg exerts a central action on the cardiovascular system via the opioid in the lateral ventricle.

Amygdala↗
PubMed1993

Treatment of twin-twin transfusion syndrome.

OBJECTIVE: To determine whether therapeutic amniocentesis may improve outcomes in patients with twin-twin transfusion syndrome. METHODS: Thirteen patients with possible twin-twin transfusion syndrome were evaluated for treatment. Therapeutic amniocenteses were performed on nine, and four patients were managed conservatively depending on the clinical severity of the twin-twin transfusion syndrome. RESULTS: Therapeutic amniocenteses resolved the syndrome in three of nine cases, with an overall neonatal survival rate of 83.3% (15 of 18) and neonatal morbidity of 53.3% (eight of 15) among the survivors. The survival rate in patients with expectant management was 75% (six of eight), with a neonatal morbidity of 33.3% (two of six). An association between amniotic fluid status and fetal outcomes was observed. Patients with normalization of polyhydramniosoligohydramnios had the best outcomes. CONCLUSION: Early, aggressive amniocentesis may be an effective therapy for twin-twin transfusion syndrome. Therapeutic amniocentesis may have the capability to alter inter-fetal blood flow, possibly as a result of changes in intravascular pressure, which are related to changes in intra-amniotic pressure.

Adult↗
PubMed1993

Cartilage warping: an experimental model.

Cadaveric cartilage was cut into blocks with a newly devised cartilage cutter. Over one-hundred pieces of cartilage were used to define a kinetics curve of cartilage warping. Kinetics curves were developed for a control group of cartilage blocks placed in saline-soaked gauze (n = 46). In addition, kinetics curves were developed for cartilage placed in hypotonic saline (n = 14), hypertonic saline (n = 14), and cyanoacrylate glue (n = 6). Photographs of all groups were taken at timed intervals in order to plot the cartilage warping. It was found that pieces of cartilage which were cut peripherally (n = 6) warped twice as much as those cut centrally (n = 40). This was significant to p = 0.001. Within 15 minutes, centrally cut pieces of cartilage warped to approximately 90 percent of their end warpage; on the other hand, peripherally cut pieces of cartilage required 30 minutes to warp 90 percent of their destined warpage. The variables used did not significantly alter the kinetics curves as compared with control.

Cadaver↗
PubMed1993

Ultrastructural study of moniliformin induced lesions of myocardium in rats and mice.

Effects of moniliformin on the ultrastructure of the myocardium of mice and rats were studied. Mice were given moniliformin orally at a dose of 29.46 mg.kg-1 the LD50. One h after dosing, lesions of the mitochondria of the myocardial cells were found which became more severe in 2 and 3 h. Ultrastructural lesions were also observed in the myofibrils and sarcolemma. Rats were given moniliformin orally at the dosage of 6 mg.kg-1 once daily for 56 d. Lesions of mitochondria and myofibrils were relatively mild. In the myocardiac specimens taken from the 21d post-toxin administration, lesions of the sarcolemma became more obvious. These moniliformin-induced lesions were similar to the ultrastructural changes in the myocardium of patients with Keshan disease. Our findings indicate that there may be a close and important relationship between moniliformin intoxication and Keshan disease.

Animals↗
PubMed1992

Hydrogen exchange in native and alcohol forms of ubiquitin.

Ubiquitin adopts a non-native folded structure in 60% methanol solution at low pH. Two-dimensional nuclear magnetic resonance (2D NMR) was used to measure the hydrogen-exchange rates of backbone amide protons of ubiquitin in both native and methanol forms, and to characterize the structure of ubiquitin in the methanol state. Protection factors (the ratios of experimentally determined exchange rates to the rates calculated for an unfolded polypeptide) for protons in the native form of ubiquitin range from less than 10 to greater than 10(5). Most of the protons that are protected from exchange are located in regions of hydrogen-bonded secondary structure. The most strongly protected backbone amide protons are those of residues comprising the hydrophobic core. Hydrogen exchange from ubiquitin in methanol solution was too rapid to measure directly by 2D NMR, so a labeling scheme was employed, in which exchange with solvent occurred while the protein was in methanol solution. Exchange was quenched by dilution with aqueous buffer after the desired labeling time, and proton occupancies were measured by 1H NMR of the native form of the protein. Protection factors for protons in the methanol form of ubiquitin range from 2.6 to 42, with all protected protons located in hydrogen-bonded structure in the native form. Again, the most strongly protected protons are those of residues in the hydrophobic core. Comparison of the patterns of the hydrogen-exchange rates in the native and methanol forms indicates that almost all of the native secondary structure persists in the methanol form, but that it is almost uniformly destabilized by 4-6 kcal/mol.(ABSTRACT TRUNCATED AT 250 WORDS)

Hydrogen↗
PubMed1992

cDNA sequence of a second fibrinogen alpha chain in lamprey: an archetypal version alignable with full-length beta and gamma chains.

The message for a second fibrinogen alpha chain has been cloned from a lamprey liver cDNA library. The sequence is unique in that the amino-terminal half is homologous to all other known alpha chains, including another from lamprey, but its carboxyl-terminal half is homologous to the carboxyl-terminal portions of beta and gamma chains, segments that compose the distal globular regions of fibrinogen. The structural pattern of this newly discovered alpha chain suggests that it could be a direct descendant of the archetypal chain that existed prior to the gene duplications that led to unique beta and gamma chains and before the dislocating events that gave rise to contemporary alpha chains.

Amino Acid Sequence↗
PubMed1992

Antioxidant activity of two dibenzocyclooctene lignans on the aged and ischemic brain in rats.

The effects of two dibenzocyclooctene lignans on peroxidative damage of aging and ischemic rat brain were studied. Incubation of eight-month-old rat brain mitochondria and membrane suspension with Fe(2+)-cysteine resulted in the formation of malondialdehyde (MDA) and decrease of ATPase activity. Schisanhenol (Sal) (10(-4) M) completely inhibited the peroxidative damages of brain mitochondria and membrane of rats. The swelling and disintegration of brain mitochondria, as well as the reduction of brain membrane fluidity induced by Fe(2+)-cysteine were also prevented by Sal. The results of imitative experiment of ischemia and reperfusion of brain mitochondria and membrane in vitro indicated that Sal significantly impeded production of MDA and loss of ATPase activity induced by reoxygenation following anoxia. Oral administration of Sal induced increase of cytosol glutathione-peroxidase of brain in mice under the condition of reoxygenation following anoxia. The other compound schizandrin (Sin B) also has similar activity. But its potency is weaker than that of Sal. All these results indicate that Sal and Sin B have protective action against oxidative stress.

Adenosine Triphosphatases↗
PubMed1992

Mutations in the V2 vasopressin receptor gene are associated with X-linked nephrogenic diabetes insipidus.

X-linked nephrogenic diabetes insipidus (NDI) is a rare disorder in which the kidney is insensitive to the antidiuretic hormone, vasopressin. It has been proposed that the kidney-specific V2 vasopressin receptor, a G protein-coupled receptor, is defective in this disorder as both the disease and the receptor map to Xq28. We report six unique mutations in the V2 receptor gene of five unrelated NDI patients, with one patient having two mutations. The most severely affected patient has a nonsense mutation which would terminate the protein in transmembrane domain III. Other mutations include three missense mutations, a frameshift and one small in-frame deletion. These results represent one of the first examples of recessive mutations affecting a G protein-coupled receptor.

Amino Acid Sequence↗
PubMed1992

[A population-based study on incidence of idiopathic cardiomyopathy in Nanjing, 1985-1989].

The epidemiology of idiopathic cardiomyopathy (ICM) is largely unknown among Chinese population. The purpose of this study was to document the incidence of ICM in the entire residents aged less than 60 years in Nanjing city during the five year period from 1985 to 1989. Using the case registered method it was identified that 275 new cases of ICM collecting from all of the clinically diagnosed outpatients and inpatients in the 14 related hospitals within the city among 2,098,175 residents for years 1985-1989. Over all incidence rate was 2.6 per 100,000 person-years, the age-and sex-adjusted average annual rate being 2.1 per 100,000 directly according to the standardized population of China in 1964 (95% confidence interval 1.9-2.2). This incidence rate was increased from 1.7 per 100,000 in 1985 to 3.3 per 100,000 in 1989 and progressively increasing with aging especially in the groups over 20 years old. Among these 275 patients with ICM, 134 were classified to idiopathic dilated cardiomyopathy (IDCM) and 132 to idiopathic hypertrophic cardiomyopathy (IHCM). Both the average annual incidence rates of IDCM and IHCM were 1.3 per 100,000 and the age-and sex-adjusted rates were 1.1 per 100,000 (95% CI 0.9-1.2) in IDCN and 0.9 per 100,000 (95% CI 0.8-1.0) in IHCM, respectively. The incidence rate of ICM in male was 3.0 significantly higher than 2.2 per 100,000 in female especially in IHCM. The result of this survey is first provided with incidence data of ICM on a broad general population-based study in our country and may be of value in further studying its epidemiology and etiology.

Adolescent↗
PubMed1992

Protective effect of schisanhenol against oxygen radical induced mitochondrial toxicity on rat heart and liver.

Schisanhenol (SAL) had been shown to have potent antioxidant activities. The protective effects of SAL against oxygen radical induced mitochondrial injuries of rat heart and liver were investigated in the present study. The ferrous-cysteine induced mitochondrial lipid peroxidation was significantly inhibited by SAL, while the loss of ATPase activity induced by the lipid peroxidation was prevented. The rigidification of mitochondrial membrane, as well as swelling, lysis and disintegration of the mitochondria induced by ferrous-cysteine were all significantly inhibited by SAL. These results further confirm that SAL possesses antioxidant activity.

Animals↗
PubMed1991

Characterization of cross-linking of cell walls of Bacillus subtilis by a combination of magic-angle spinning NMR and gas chromatography-mass spectrometry of both intact and hydrolyzed 13C- and 15N-labeled cell-wall peptidoglycan.

Cross-polarization magic-angle spinning 13C and 15N NMR, rotational-echo double resonance 13C NMR, and delays alternating with nutation for tailored excitation-difference 13C NMR spectra have been obtained from lyophilized cell walls of Bacillus subtilis grown on a synthetic medium containing D,L-[2-13C, 15N]aspartate and D-[1-13C]alanine. Label from aspartate is incorporated into D-glutamic acid and m-diaminopimelic acid of cell-wall peptidoglycan, while label from alanine appears in the C-1 positions of both D- and L-alanyl residues. The cross-link index (the fraction of peptide stems joined by an isopeptide covalent bond) is obtained directly from analysis of the results of the 13C NMR experiments. However, specific isotopic enrichments of cell-wall components cannot be obtained from NMR data alone. The latter are determined either from a gas chromatographic-mass spectrometric analysis of the amino acids derived from hydrolysis of cell-wall peptidoglycan, or from a combination of NMR and gas chromatographic-mass spectrometric results. The combined analysis is overdetermined and so involves the least error for evaluations of both the cross-link index and the isotopic enrichments. The cross-link index is 0.33 +/- 0.03 for cell walls of B. subtilis grown in the presence of the antibiotic, cephalothin.

Amino Acids↗