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Biomedical subjects

M Sun

Publications and source records attributed to M Sun.

At least 217 records · Page 12Linked to original sources
PubMed1995

Leptomeningeal tumor in primary central nervous system lymphoma: recognition, significance, and implications.

The true incidence of leptomeningeal tumor in primary central nervous system lymphoma is unknown. We studied prospectively the cerebrospinal fluid profile of 96 patients without acquired immunodeficiency syndrome but with primary central nervous system lymphoma at diagnosis, at completion of treatment, and at recurrence. Magnetic resonance images and pathology slides were examined for evidence of leptomeningeal tumor. Leptomeningeal tumor was diagnosed by (1) positive findings on cerebrospinal fluid cytology, (2) leptomeningeal or subependymal enhancement on magnetic resonance imaging, or (3) pathological evidence of leptomeningeal tumor. We recorded whether treatment directed against the leptomeninges was given. Cerebrospinal fluid was examined in 86 of 96 patients at diagnosis and 29 of 42 at recurrence. The incidence of leptomeningeal tumor was 42% at diagnosis and 41% at recurrence. Only elevated levels of protein and lactate dehydrogenase isoenzyme-5 were significantly associated with leptomeningeal tumor (p = 0.012, p = 0.016, respectively). Treatment against the leptomeninges was significantly associated with the probability of achieving a complete response and a longer freedom from relapse. Patients older than 50 years had a worse disease-specific survival but a similar probability of responding to therapy as younger patients. Our data show that leptomeningeal tumor in primary central nervous system lymphoma is more prevalent than originally thought, and indicate the need for therapy inclusive of the leptomeninges in all patients.

Arachnoid↗
PubMed1995

Action of organophosphate anticholinesterases on the three conformational states of nicotinic receptor.

Organophosphate and other ligands were examined for binding on the membrane-bond nicotinic receptor at three conformational states. Soman (pinacolyl methylphosphonofluoridate), sarin (isopropyl methylphosphonofluoridate, tabun (ethyl N-dimethylphosphoramidocyanidate) and phencyclidine did not show any effect on the binding of [25I]alpha-cobrotoxin to the nicotinic receptor. However, VX, O-ethyl-S-(2-diisopropylaminoethyl) methylphosphonothiolate, at concentrations higher than 10 umol/L exhibited profound inhibition on the equilibrium binding rates in a concentration-dependent manner. Agonist nicotine and antagonist d-tubocurarine also showed significant inhibitions.

Animals↗
PubMed1995

The change of carnitine content in seminal plasma after reversible injection occlusion of vas deferens.

The change in carnitine content in seminal plasma after reversible injection occlusion of vas deferens (RIOVD) was observed. RIOVD is a safe, effective and simple method of male fertility control. Carnitine was determined by microenzymatic method. The incidence of sperm disappearance increased with the duration of RIOVD and reached 90% at the end of 12 months after operation. Before RIOVD, the mean value of carnitine in seminal plasma was 336.9 +/- 78.1 nmol/ml (X +/- SD, n = 58); after RIOVD, the mean value of seminal plasma carnitine was 112.7 +/- 50.7 nmol/ml (n = 172) in the group with sperm disappearance, and 172.5 +/- 71.7 nmol/ml (n = 51) in the group without sperm disappearance. There was a significant difference in carnitine content between pre-operation and postoperation (p < 0.01). After RIOVD, the carnitine concentration in seminal plasma of the group with sperm disappearance was lower than that of the group without sperm disappearance (p < 0.01). The results suggest that carnitine content in seminal plasma following RIOVD may be a reference index for judging the success or failure of the operation.

Carnitine↗
PubMed1995

Trichomonas vaginalis and cervical cancer. A prospective study in China.

The relationship between Trichomonas vaginalis infection and cervical cancer was investigated prospectively in a cohort of 16,797 women aged 25 years or more who were followed from 1974 to 1985 within the framework of a cervical screening program in Jingan, China. Personal interviews were conducted by trained interviewers when the women first entered the screening program. At initial screening, 421 (2.51%) women had a positive cytologic diagnosis of T. vaginalis infection. Ninety-nine incident cases of pathologically confirmed squamous cell carcinoma were identified from the cohort, with a total of 140,018 person-years of observation. T. vaginalis infection was found to contribute to the risk of cervical cancer, as determined by crude estimates and after adjustment for potential confounding effects. In a multiple proportional hazards model, the relative risk for cervical cancer was 3.3 (95% confidence interval: 1.5 to 7.4) among women with T. vaginalis infection. Furthermore, in the multivariate analysis, increased risk of cervical cancer was associated with the following factors: number of extramarital sexual partners of both the subjects and their spouses, cigarette smoking, and irregular menstruation. Having a large number of negative Pap smears was associated with lower risk. This study suggests that there might be an association between T. vaginalis infection and the risk of cervical cancer, but only 4 to 5% of cervical cancer in Chinese women may be attributable to T. vaginalis infection.

Adult↗
PubMed1995

[Two autopsy cases of malignant mixed müllerian tumor of the uterus with metastasis to alimentary tract and liver].

Two autopsy cases (69 and 87-year-old women) of malignant mixed müllerian tumor (MMMT) following radiation therapy for uterine cervical cancer sixteen and twenty years ago respectively were reported. They were admitted due to abdominal pain and diagnosed as ileus. In the first case, CT examination revealed a tumor measuring about 8 x 10 cm in size in the uterine posterior wall. Recurrence of the uterine cancer was suspected and hysterooophorectomy combined with sigmoidectomy was performed. In the second case, artificial anus formation was performed because of sigmoid stricture by the invasion of the tumor. Histologically, tumors in both cases were composed of carcinomatous and sarcomatous components including heterologous elements such as cartilage. The patients died of extensive spreads and metastasis in the liver and alimentary tract.

Aged↗
PubMed1995

[Detection of mutation in insulin receptor gene in patients with essential hypertension].

We have analyzed single-stranded conformational polymorphism (SSCP) to screen for mutation in exon 17 of insulin receptor gene in 46 patients with hypertension and 49 normotensive controls. Three different SSCP patterns were detected in both patients and controls and the frequency of pattern I was 54.3% and 32.7% (chi 2 = 3.71, P = 0.05) in patients and controls respectively; The frequency of pattern II was 61.3% and 26.1% (chi 2 = 10.49, P = 0.001) in controls and patients respectively; the frequency of pattern III did not differ between controls and patients. Based on direct sequencing, the differences between pattern II and pattern I were explained by a mutation substituting at position 1040, GAG1040-->GAA1040, which suggests that codon GAA1040 may be a genetic marker for susceptibility to essential hypertension in Chinese.

Adult↗
PubMed1995

[Vasoactive intestinal polypeptide prevents injury of pulmonary vascular permeability due to xanthine with xanthine oxidase].

Hyperpermeability is the crux of pathogenesis of sudden lung edema in many pulmonary disorders, especially in acute lung injury and acute respiratory distress syndrome (ARDS). Using our modified method for assessment of pulmonary vascular permeability, we observed the effects of xanthine with xanthine oxidase (X-XO) perfused in rat pulmonary artery and the protection of vasoactive intestinal polypeptide (VIP) against the injury of pulmonary vascular permeability. After addition of xanthine oxidase in the perfusate reservoir containing xanthine, 125I-albumin leak index (125I-ALI) was remarkably increased while peak airway pressure (Paw) showed no significant increase, and perfusion pressure of pulmonary artery (Ppa) and lung wet/dry weight ratio (W/D) were only slightly increased. Xanthine plus xanthine oxidase also increased thromboxane B2 (TX B2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in the perfusate. Treatment with VIP obviously reduced or totally prevented all signs of injury. Simultaneously, VIP also diminished or abolished the associated generation of arachidonate products. The results indicated that VIP has potent protective activity against injury of pulmonary vascular permeability and may be a physiological modulator of inflammatory damage to vascular endothelium associated with toxic oxygen metabolites.

6-Ketoprostaglandin F1 alpha↗
PubMed1995

[Multiple gene alterations involved in the processor of human gastric carcinogenesis].

The investigation of molecular evidence of gastric carcinoma will be contributable to the prevention, gene diagnosis and therapy of human gastric neoplasms. To determine the specific genetic change in human gastric cancer (HGC) and precancerous lesions, we analysized FISH, PCR/SSCP, IHC and DNA sequencing by using multiple probes to detect the gene abnormalities (mutation, deletion, amplification or overexpression of genes) of 67 fresh tumors, 63 endoscopic biopsies including 30 dysplasia (DYS) and 33 intestinal metaplasia (IM, and 4 tumor cell lines from HGC patients. Multiple genetic abnormalities including hypomethylation of H-ras gene, amplification and overexpression of met and erbB2, deletion of APC, mts1/p16, p53 and nm23 gene and point mutation of p53 gene were noted in HGC and precancerous lesion of human gastric mucosa. Among these changes, p53 gene was the highest frequence genetic alteration in 39/67 (54-58%) of gastric carcinoma. These results indicate that overexpression of met and H-ras occurs at early stage in progression of neoplasia, amplification of met, erbB2 and akt2 gene occurs at progressing stage of tumorigenesis, deletion of p53, APC, mts1/p16 and nm23 occurs at advanced stage in the progression of cancer. The abnormalities should be associated with malignant phenotypes: poor differentiation, vascular invasion, lymph nodes metastasis, and low survival time. We detected p53 gene mutation in both cancer and precancerous lesions of IM and DYS. These results suggest that p53 may be a susceptible gene and alteration of p53 gene plays an important role in the development of HGC.

Gastric Mucosa↗
PubMed1995

[Conservative surgery and radiation therapy in the treatment of operable breast cancer].

Forty-five patients with breast cancer were treated in our hospital by conservative surgery and radiation therapy from 1985 to 1994. There were 22 patients in stage I and 23 in stage II. All the patients were received breast-preserved operation including segmental resection and axillary node dissection. Routine postoperative irradiation was given to the patients with or without regional lymphatic melastasis. The indications of chemotherapy and endocrinotherapy were as same as those of Halsted's radical mastectomy. The duration of following-up was 3-5 years. The 5-year local recurrence was 8.8%. The 5-year OS was 94.1%, and DFS 94.1%.

Adenocarcinoma↗
PubMed1994

Molecular cloning of a proteolytic antibody light chain.

The cDNA for an antibody light chain raised by immunization against vasoactive intestinal peptide (VIP) was cloned in a bacterial expression vector, and the recombinant light chain was purified to electrophoretic homogeneity. The light chain catalyzed the hydrolysis of VIP efficiently owing to its comparatively high affinity for the substrate. In control experiments, the catalytic activity was preserved at a constant level after further chromatography of the light chain on anion-exchange and gel-filtration fast protein liquid chromatography columns, and it was removed by immunoadsorption with immobilized anti-mouse light chain antibody. The amide bond linking methylcoumarinamide (MCA) and arginine in a tripeptide unrelated in sequence to VIP was cleaved by the light chain with lower affinity and kinetic efficiency (kcat/Km). Hydrolysis of the peptidyl-MCA conjugate was inhibited competitively by the alternate substrate, VIP. The Ki and Km values for VIP were in the same range, indicating that peptide-MCA and VIP hydrolysis occurs at a common catalytic site in the light chain. Molecular modeling suggested the presence of a serine protease-like site in the light chain. This was supported by inhibition of the hydrolytic activity by serine protease inhibitors, but not by inhibitors of other classes of proteases. These observations suggest a poorly discriminatory catalytic site, with specificity for VIP arising chiefly by means of the antigen recognition function of the light chain combining site.

Amino Acid Sequence↗
PubMed1994

Proteolytic activity of an antibody light chain.

The light chain (L chain) of a mAb raised against unactivated vasoactive intestinal peptide (VIP) hydrolyzed this peptide, whereas the heavy chain (H chain) and an irrelevant L chain were without activity. The reaction kinetics were consistent with efficient substrate recognition by the anti-VIP L chain compared with conventional proteases. The L chain cleaved four peptide bonds clustered between residues 16 and 21 in VIP. Mixtures of the L chain with its H chain partner displayed reduced hydrolytic activity compared with the free L chain, suggesting that the H chain is a modulator of the catalytic activity. These observations suggest: 1) the immune system can generate catalytic sites in the L chain subunit of Abs found in response to polypeptide Ags, and 2) free L chains found in vivo could display an Ag-specific catalytic function.

Amino Acid Sequence↗
PubMed1994

Antigen recognition by an antibody light chain.

A monoclonal antibody to vasoactive intestinal polypeptide (VIP) was reduced and alkylated and its light and heavy chains were purified by denaturing gel filtration. Following renaturation, the light chain displayed sequence-specific binding of VIP. The specific VIP binding activity of several fractions spanning the light chain peak recovered from the gel filtration column was constant, the light chain was electrophoretically homogeneous, the VIP binding activity was precipitated by anti-light chain antibody but not anti-heavy chain antibody and the activity remained associated with a light chain fraction recovered by resolutive chromatography on a hydroxylapatite column. N-terminal amino acid sequencing of the light and heavy chain fractions confirmed the purity of these proteins and suggested that the VL and VH regions belonged to kappa-family II and gamma-family III, respectively. The VIP-binding affinity of the light chain was only 5-fold lower than that of the parent antibody and the light chain did not bind unrelated peptides. These observations suggest that light chains display structural characteristics necessary for high affinity antigen binding.

Amino Acid Sequence↗
PubMed1994

Rectal temperature changes during sleep state transitions in term and preterm neonates at postconceptional term ages.

Mean rectal temperatures in neonates were investigated during sleep state transitions as assessed by visually analyzed electroencephalographic-polygraphic recordings. Continuous 3-hour studies were obtained on 3 term and 5 preterm infants at postconceptional term ages using a 24-channel computerized monitoring system. In the study, 1,461 min were assigned an EEG state by traditional criteria. Mean rectal temperature measurements were tabulated for each minute of sleep. Data were analyzed both as 1,461 consecutive minutes of sleep, and as 28 complete ultradian neonatal sleep cycles. Exploratory analyses were performed using t tests, Mann-Whitney U tests, and one-way analysis of variance. Decreases in mean rectal temperatures followed a transition from active to quiet sleep for only the term group. The preterm group had higher temperatures at sleep onset than the term group and demonstrated no changes during state transitions. Higher temperatures were maintained in the preterm group during both active and quiet sleep (i.e., 36.7 degrees C versus 36.4 degrees C, P = .02) when 28 complete cycles of sleep were compared and during the transition when 658 min of active sleep were compared to 617 min of quiet sleep. These findings are preliminary; however, the phenomenon of state-dependent changes in mean rectal temperature in neonates based on electroencephalographic sleep is unreported. Higher mean rectal temperatures during active sleep and altered temperature responses during transition to quiet sleep in the preterm infant suggest altered brain function because of the preterm infant's adaptation to the extrauterine experience.

Autonomic Nervous System↗
PubMed1994

Comparisons of EEG spectral and correlation measures between healthy term and preterm infants.

Continuous 12-hour electroencephalography (EEG)-sleep studies were acquired by a computerized monitoring system under environmentally controlled conditions for 2 groups of neonates. Eighteen health preterm infants at a postconceptional term age were matched to 18 term infants. These 2 groups were also matched for gender, race, and socioeconomic class. For the entire 12-hour recording, relative spectral power values (i.e., ratio of specific EEG power in specific frequency band compared to total EEG power) were significantly reduced in the preterm group for theta (P < or = .007), alpha (P < or = .001), and beta (P < or = .018) frequency bands, while delta remained unchanged. Correlations between 91 pairs of EEG channels were also calculated and the preterm infants had significantly higher correlation values in 27 of the 91 pairs of channels (P < .05); 14 interhemispheric, 8 intrahemispheric, and 5 sagittal combinations, while 3 intrahemispheric combinations were higher in the term group. Fewer functional neuronal aggregates generate less oscillatory potential (i.e., lower spectral power) in the theta through beta frequency ranges in the preterm infant, while greater cortical connectivity (i.e., higher correlations) exists in many brain regions by postconceptional term ages in this group. These findings suggest a functional alteration in brain development of the preterm infant as a result of prolonged extrauterine experience and/or prematurity.

Action Potentials↗
PubMed1994

Seroprevalence of human T-lymphotropic virus, hepatitis C virus, and human immunodeficiency virus in Asian American potential bone marrow donors.

BACKGROUND: Asian Americans are generally underrepresented both as volunteer blood and bone marrow donors. STUDY DESIGN AND METHODS: To investigate the risk of transfusion transmission of viruses that is associated with increasing participation by Asian American donors, antibodies to human T-lymphotropic virus (HTLV), hepatitis C, and human immunodeficiency virus in Asian American volunteers recruited as potential bone marrow donors were measured. A total of 1354 Asian Americans were enrolled in the study, of whom 54 percent were Chinese, 26 percent Japanese, 9 percent Filipino, 4 percent Korean, 3 percent Indian, and 5 percent of other Asian or mixed Asian and other ethnicity. The majority of the study population was aged 20 through 49 and of high socioeconomic status, as indicated by education and income. Viral antibodies were measured with both screening enzyme-linked immunosorbent assays and supplemental testing, and polymerase chain reaction was used to resolve discrepant HTLV results. RESULTS: Confirmed seroprevalence rates for HTLV were 0.15 percent with one manufacturer's Western blot and 0.3 percent with the other; however, no sample was positive for HTLV types I or II in polymerase chain reaction. Confirmed seroprevalence to hepatitis C virus was 0.5 percent. No subject was seropositive for human immunodeficiency virus. CONCLUSION: On the basis of the moderate size and high education level of this study population, it is concluded that Asian American volunteer bone marrow donors do not pose a greater risk for transmission of HTLV type I or II, human immunodeficiency virus, or hepatitis C virus than does the average American blood donor.

Adolescent↗
PubMed1994

Respiratory syncytial virus-specific cell-mediated immune responses after vaccination with a purified fusion protein subunit vaccine.

Vaccination with a respiratory syncytial virus (RSV) fusion protein subunit vaccine (PFP-2) was done to determine if this vaccine induced evidence of cell-mediated immunity to RSV and if cell-mediated immunity prevented RSV reinfection. Healthy children 12-18 months old received 50 micrograms of PFP-2 or a saline control. Lymphocyte transformation (LTF) responses were determined before and 1 and 6 months after vaccination. PFP-2 induced positive LTF responses in 5 (83%) of 6 subjects whose prevaccination samples lacked evidence of cell-mediated immunity. Positive LTF responses in prevaccination samples were not boosted but were more persistent in vaccinees than in controls. Positive LTF responses were not associated with protection against subsequent infection. Immunization with PFP-2 induces correlates of cell-mediated immunity, but this immunity does not appear to be a critical component of protection.

Double-Blind Method↗