Biomedical subjects

M Sun

Publications and source records attributed to M Sun.

At least 73 records · Page 4Linked to original sources

PubMed1997

Snmp-1, a novel membrane protein of olfactory neurons of the silk moth Antheraea polyphemus with homology to the CD36 family of membrane proteins.

While olfactory neurons of silk moths are well known for their exquisite sensitivity to sex pheromone odorants, molecular mechanisms underlying this sensitivity are poorly understood. In searching for proteins that might support olfactory mechanisms, we characterized the protein profile of olfactory neuron receptor membranes of the wild silk moth Antheraea polyphemus. We have purified and cloned a prominent 67-kDa protein which we have named Snmp-1 (sensory neuron membrane protein-1). Northern blot analysis suggests that Snmp-1 is uniquely expressed in antennal tissue; in situ hybridization and immunocytochemical analyses show that Snmp-1 is expressed in olfactory neurons and that the protein is localized to the cilia, dendrites, and somata but not the axons. Snmp-1 mRNA expression increases significantly 1-2 days before the end of adult development, coincident with the functional maturation of the olfactory system. Sequence analysis suggests Snmp-1 is homologous with the CD36 protein family, a phylogenetically diverse family of receptor-like membrane proteins. CD36 family proteins are characterized as having two transmembrane domains and interacting with proteinaceous ligands; Snmp-1 is the first member of this family identified in nervous tissue. These findings argue that Snmp-1 has an important role in olfaction; possible roles of Snmp-1 in odorant detection are discussed.

Amino Acid Sequence↗

PubMed1997

Altered cleavage site preference of a proteolytic antibody light chain induced by denaturation.

A recombinant antibody light chain (L chain) maintained under non-denaturing conditions displayed preferential cleavage of synthetic peptides conjugated to methylcoumarinamide (MCA) on the C-terminal side of Arg and Lys residues. The same L chain renatured from a denaturing solvent (guanidine hydrochloride) acquired the capability of cleaving Tyr-MCA and Leu-MCA bonds, and its ability to cleave MCA linked to basic residues was decreased. The altered cleavage preference was accompanied by a conformational transition in the protein, evident from the fluorescence emission spectra. These observations suggest the feasibility of redirecting the cleavage specificity via alterations in the conformation of proteolytic antibody combining sites.

Amino Acid Sequence↗

PubMed1997

The conformation of DNA packaged in bacteriophage G.

When packaged in a bacteriophage capsid, double-stranded DNA occupies a cavity whose volume is roughly twice the volume of the DNA double helix. The data thus far have not revealed whether the compactness of packaged bacteriophage DNA is achieved by folding of the DNA, undirectional winding of the DNA, or a combination of both folding and winding. To assist in discriminating among these possibilities, the present study uses electron microscopy, together with ultraviolet light-induced DNA-DNA cross-linking, to obtain the following information about the conformation of DNA packaged in the comparatively large bacteriophage, G: 1) At the periphery of some negatively stained particles of bacteriophage G, electron microscopy reveals standards of DNA that are both parallel to each other and parallel to the polyhedral bacteriophage G capsid. However, these strands are not visible toward the center of the zone of packaged DNA. 2) Within some positively stained particles, electron microscopy reveals DNA-associated stain in relatively high concentration at corners of the polyhedral bacteriophage G capsid. 3) When cross-linked DNA is expelled from its capsid during preparation for electron microscopy, some DNA molecules consist primarily of a compacted central region, surrounded by DNA strands that appear to be unravelling at multiple positions uniformly distributed around the compacted DNA region. The above results are explained by a previously presented model in which DNA is compacted by folding to form 12 icosahedrally arranged pear-shaped rings.

Bacteriophages↗

PubMed1997

ICV beta-hydroxybutyrate: effects on food intake, body composition, and body weight in rats.

This study examined the effect of long-term intracerebroventricular (ICV) infusion of beta-hydroxybutyrate (beta HB) on food intake, diet selection, body weight, and body composition in rats. Female rats were divided into 2 groups and implanted with a 28-day osmotic pump connected to a lateral cerebroventricular cannula. One group was infused with artificial cerebrospinal fluid (aCSF) and the other with beta HB for 28 days. The rats had free access to both a high-fat/low-carbohydrate and a low-fat/high-carbohydrate diet (isocaloric) for the 28-day infusion period. The group infused with beta HB had a significantly lower body weight gain during the infusion period. Cumulative food intake increased in the same manner in both groups. Fat pad weights and carcass lipid content were significantly higher in beta HB rats, despite the equivalent caloric intake in both groups and the decreased body weight. Our observations are in accord with earlier studies indicating that beta HB infused ICV reduces body weight, but not necessarily food intake. Increased adiposity in association with decreased body weight change in beta HB-infused rats strongly suggests that energy is being partitioned to fat deposition at the expense of lean tissue growth when ketone bodies are infused into the cerebroventricles.

3-Hydroxybutyric Acid↗

PubMed1997

Prognostic significance of detection of prostate-specific antigen transcripts in the peripheral blood of patients with metastatic androgen-independent prostatic carcinoma.

OBJECTIVES: To evaluate the prognostic significance of reverse transcriptase polymerase chain reaction (RT PCR) detection of prostate-specific antigen (PSA) mRNA in relation to survival in patients with metastatic androgen-independent prostatic carcinoma (AIPC). METHODS: Peripheral blood from 122 men (64 from Memorial Sloan-Kettering Cancer Center [MSKCC] and 58 from the Dana Farber Cancer Institute [DFCI]) with metastatic (Stage D2) AIPC was analyzed for PSA mRNA using RT PCR. Forty-one controls without prostatic carcinoma were also evaluated. RESULTS: RT PCR positivity for PSA mRNA was present in 24 of the 64 (38%) patients seen at MSKCC and in 26 of the 58 (45%) patients followed at DFCI. All control individuals were PSA PCR negative. There was a significant correlation between RT PCR positivity and decreased survival in each of the Memorial and Dana Farber population (P = 0.028 and 0.039, respectively). Serum PSA (at time of blood collection for PCR) was not predictive of survival as a continuous variable in the MSKCC [P = 0.31] and the DFCI (P = 0.09) groups. RT PCR for PSA mRNA was found to be independent from and superior to serum PSA in predicting survival in both the MSKCC and DFCI populations (P = 0.048 and P = 0.027, respectively). CONCLUSIONS: The detection of PSA mRNA in the peripheral blood by RT PCR is a predictor of survival in patients with metastatic AIPC, and PCR is superior to a single serum PSA measurement. Further studies are needed to test the value of this factor in comparison to and coupled with other prognostic parameters.

Adult↗

PubMed1997

Cocaine and inhibition of nitric oxide synthesis produce opioid-mediated antinociception.

Cocaine and nitric oxide are known to influence the perception of pain. The present study sought to determine if the endogenous opioid peptide system participates in cocaine-induced antinociception and antinociception produced by antagonism of nitric oxide. Pain perception was measured using the hot plate test. Administration of cocaine (25 mg/kg) to male rats resulted in a significant increase in reaction time in the hot plate test, which was reversed by treatment with 3, 10, and 30 mg/kg of the opiate antagonist, naloxone. In rats that were not treated with cocaine, doses of 30 and 60 mg/kg of naloxone significantly reduced hot plate reaction Time. Treatment of animals with the nitric oxide synthase inhibitor, N omega nitro-L-arginine, produced a significant increase in response time to the hot plate, which was reversed by administration of naloxone. These data indicate that antinociception produced in the rat by cocaine appears to have a supraspinal component and to involve activation of endogenous opioid peptide activity in the brain. The results also suggest a tonic inhibition of endogenous opioid peptide activity by nitric oxide, which when antagonized, results in diminished response to pain.

Animals↗

PubMed1997

Adenocarcinomas of the esophagus and gastric cardia: the role of diet.

The incidence of adenocarcinomas of the esophagus and gastric cardia (ACEGC) has been increasing for the past 10-15 years in the United States. The reason for this increase is unknown. This hospital-based case-control study was conducted to assess the effects of dietary and nutritional factors on the risk of ACECG. A total of 95 incident cases with pathological diagnosis and 132 cancer-free controls were included in the study. Patients were recruited at Memorial Sloan-Kettering Cancer Center from 1 November 1992 to 1 November 1994. Epidemiologic data were collected by a modified National Cancer Institute Health Habits History Questionnaire. Nutritional and dietary factors were analyzed using a logistic regression model. Increased risk of ACEGC was significantly related to higher intake of dietary calories and fat after controlling for several potential confounding factors. Decreased risk of ACEGC was significantly associated with high ingestion of dietary fiber, lutein, niacin, vitamin B6, iron, and zinc. Higher intakes of vitamin A, beta-carotene, vitamin E, folate, phosphorus, and potassium were associated with a decreased risk of the disease, but these were not statistically significant. The study suggests that ACEGC can be preventable through dietary interventions.

Adenocarcinoma↗

PubMed1997

Genetic susceptibility to head and neck cancer: interaction between nutrition and mutagen sensitivity.

The development of head and neck cancer may depend not only on exposure to environmental carcinogens but also on a genetically based susceptibility to carcinogen-induced damage. This thesis presents a case-control study that demonstrates the significance of mutagen sensitivity, a measure of an individual's intrinsic DNA repair capacity against free radical damage, as a risk factor for the disease. As part of the case-control analysis, 167 previously untreated patients and 177 age- and sex-matched healthy controls were assessed for various lifestyle factors including tobacco and alcohol habits, occupational exposures, and diet. Mutagen sensitivity expressed by each individual was determined by quantifying bleomycin-induced chromosomal breaks within peripheral blood lymphocytes in vitro. Consistent with our initial observations and those of others, mutagen hypersensitivity was strongly associated with increased risk of head and neck cancer (odds ratio, 4.95; 95% confidence interval, 2.67 to 9.17) after adjusting for age, sex, and race. Low intake of vitamins C and E was also associated with an increased risk of disease and was interactive with mutagen sensitivity in risk estimates. Individuals with both a low intake of various antioxidants and increased chromosomal sensitivity to oxidant-induced DNA damage were at greatest risk. This study supports the concept that the risk of head and neck cancer is determined by a balance of factors that either enhance or protect against free radical oxygen damage, including innate capacities for DNA repair.

Adult↗

PubMed1997

An efficient algorithm for computing multishell spherical volume conductor models in EEG dipole source localization.

Computationally localizing electrical current sources of the electroencephalographic signal requires a volume conductor model which relates theoretical scalp potentials to the dipolar source located within the modeled brain. The commonly used multishell spherical model provides this source-potential relationship using a sum of infinite series whose computation is difficult. This paper provides a closed-form approximation to this sum based on an optimal fitting to the weights of the Legendre polynomials. The second-order (third-order) approximation algorithm, implemented by a provided C-routine, requires only 100 (140) floating point operations to compute a single scalp potential in response to an arbitrary current dipole located within a four-shell spherical volume conductor model. This cost of computation represents only 6.3% (8.9%) of that required by the direct method. The relative mean square error, measured by using 20,000 random dipoles distributed within the modeled brain, in only 0.29% (0.066%).

Algorithms↗

PubMed1997

Efficacy of prophylactic aerosol amphotericin B lipid complex in a rat model of pulmonary aspergillosis.

Invasive pulmonary aspergillosis remains an important cause of morbidity and mortality among transplant recipients and patients receiving cancer chemotherapy. The lipid-associated formulation of amphotericin B (AmB), AmB lipid complex (ABLC), was evaluated for its prophylactic efficacy when it was administered as an aerosol in a rat model of pulmonary aspergillosis. Aerosol ABLC (aero-ABLC), in doses from 0.4 to 1.6 mg/kg of body weight given 2 days before infection, significantly delayed mortality compared to the mortality of rats given placebo (P < 0.001). At day 10 postinfection, 50% of rats in the 0.4-mg/kg group and 75% of rats in the 1.6-mg/kg group were alive, while all control animals had died. In a second trial aero-ABLC was more effective than an equivalent dose of aerosol AmB (aero-AmB) in prolonging survival, with 100% survival at day 14 postinfection in the ABLC group, compared to 62.5% survival in the AmB group. Mean concentrations of AmB in lungs were 3.7 times higher at day 1 (P < 0.002) and almost six times higher at day 7 (P < 0.001) after treatment with aero-ABLC than after treatment with a similar dose of aero-AmB. We conclude that aero-ABLC provided higher and more prolonged levels of the parent compound in the lungs than aero-AmB and was more effective in delaying mortality from aspergillosis in this model.

Aerosols↗

PubMed1997

Improving energy expenditure estimation by using a triaxial accelerometer.

In our study of 125 subjects (53 men and 72 women) for two 24-h periods, we validated energy expenditure (EE), estimated by a triaxial accelerometer (Tritrac-R3D), by using a whole-room indirect calorimeter under close-to-normal living conditions. The estimated EE was correlated with the measured total EE for the 2 days (r = 0. 925 and r = 0.855; P < 0.001) and in minute-by-minute EE (P < 0.01). Resting EE formulated by the Tritrac was found to be similar to the measured values [standard errors of estimation (SEE) = 0.112 W/kg; P = 0.822]. The Tritrac significantly underestimated total EE, EE for physical activities, EE of sedentary and light-intensity activities, and EE for exercise such as stepping (all P < 0.001). We developed a linear and a nonlinear model to predict EE by using the acceleration components from the Tritrac. Predicted EE was significantly improved with both models in estimating total EE, total EE for physical activities, EE in low-intensity activities, minute-by-minute averaged relative difference, and minute-by-minute SEE (all P < 0. 05). Furthermore, with our generalized models and by using subjects' physical characteristics and body acceleration, EE can be estimated with higher accuracy (averaged SEE = 0.418 W/kg) than with the Tritrac model.

Acceleration↗

PubMed1997

Spatial patterns of olfactory neurons expressing specific odor receptor genes in 48-hour-old embryos of zebrafish Danio rerio.

Olfactory neurons have a complex phenotype characterized by their expression of a specific odor receptor (OR) gene and their targeting of an equally specific locus in the olfactory bulb. In the adult fish, olfactory neurons expressing specific ORs are broadly distributed in the epithelium, intermingling with neurons expressing other OR phenotypes. This distributed adult pattern has led to the suggestion that olfactory neuron phenotype is determined by a stochastic process, independent of external positional cues. However, when the fish olfactory system is established during embryogenesis it is simple in its organization, with few olfactory neurons and an olfactory epithelium that has not yet folded into the adult morphology. It is possible that positional cues might act in the embryo to establish an initial population and pattern of olfactory neuron phenotypes and that subsequent morphogenesis and neuronal addition lead to the randomized distribution of neurons. To test this possibility, we examined the spatial patterns of olfactory neurons expressing specific OR genes in 48 h embryos, a time of relative simplicity in the developing olfactory epithelium. Three-dimensional plots of neuron distributions were made, and comparison of OR expression patterns were made between right and left epithelia, between individual animals and between different OR genes. The patterns of OR gene expression were not conserved in these comparison. Mathematical analysis of 21 epithelia for the degree of order in the distribution of olfactory neurons argued strongly that the neurons expressing given ORs are randomly distributed in the 48 h embryos. These results are consistent with those observed from adult tissue and support models suggesting that extrinsic positional cues do not have a major role in specifying olfactory neuron phenotypes.

Animals↗

PubMed1997

[Study of the mechanism of regression of left ventricular hypertrophy in hypertension treated with slow-release verapamil].

Thirty-three hypertensive patients with left ventricular hypertrophy were treated with slow-release verapamil for 1 year. The left ventricula mass index (LVMI) and the concentration of intracellular calcium ion ([Ca2+]i) of lymphocytes were studied respectively at the beginning, the third, the sixth and the twelveth month of treatment. The results revealed that: 1 the LVMI was positively correlated with [Ca2+]i and mean arterial pressure (MAP); 2 the LVMI, [Ca2+]i and MAP were significantly decreased, after treatment; 3 the degree of reduction of LVMI (delta LVMI) was positively correlated with the degree of lowering of [Ca2+]i (delta [Ca2+]i) and MAP (delta MAP); 4 the LVMI and [Ca2+]i showed no significant change at the third month but significant decrease at the sixth and twelveth month of treatment. It suggests that besides the decrease of MAP the decrease of [Ca2+]i is a significant factor for mechanism of regression of LVH.

Adult↗

PubMed1997

[Prevention and treatment of stroke after hypertension for ten years in Hunan Province].

In this single blind, randomized multiple center clinical trial, the patients care period was divided into two stages. In the first stage (1985, 1-1989, 12), 984 cases were observed for 5 years whereas in the second stage (1990, 1-1994, 12), 2080 cases were observed and were subdivided into two groups, treat group and control, both were followed up for 5 years. The results showed that the prevalence of hypertension increased gradually. In the second stage, the average of blood pressure of the treatment group, using nitrendipine, was lower than that of the control group. There was significant difference between the two groups (P < 0.05). In the treatment group, the stroke and death rates were also decreased significantly as compared with the control group and the first stage group (P < 0.01).

Antihypertensive Agents↗

PubMed1997

[The study of mutation in exon 17 of insulin receptor gene in essential hypertensive pedigrees].

Using the molecular scanning technique of single-stranded conformational polymorphism, we examined the exon 17 of the insulin receptor (INSR) gene in 44 subjects of 6 essential hypertensive pedigrees and 2 normotensive pedigrees. In addition the serum levels of glucose and insulin during an oral glucose tolerance test (OGTT); blood lipid, and plasma angiotension II and angiotensinogen were done on these pedigrees. Upon direct sequence analysis, 5 individuals were found a single nucleotide substitution at the codon 1058 (CAC-->CAT), which didn't change the amino acid sequence. Among the five individuals 4 of them were from the families with history of hypertension, only one was from normotensive pedigree. Compared with those without the mutation, the individuals with the mutation had a lower ratio of fasting blood glucose to fasting serum insulin level (P < 0.01) and an elevated plasma Ang II concentration. (There was no significant difference, P > 0.05, probably due to the mutant cases which we studied were small). Thus, we conjectured that the mutation in codon 1,058 of the INSR gene might be related with the insulin resistance in hypertensive patients and subjects with the positive hypertensive history.

Adolescent↗

PubMed1997

[VP4 protein of simian rotavirus strain SA11 expressed by a baculovirus recombinant].

The complementary DNA copies of the gene 4 were prepared by reverse transcription and polymerase chain reaction (RT-PCR) from genomic RNA of simian rotavirus strain SA11. A complete VP4 gene was been inserted into a baculovirus intermediate vector pVL-1393 which was under control of the polyhedrin promoter. The outer capsid protein VP4 which was a major neutralization antigen of rotavirus, was expressed in high yield in Spodoptera frugiperda cell line. The VP4 protein expressed was recognized with a hyperimmunized serum directed against the rotavitus by immunoblot assay. Expressed VP4 protein own about 10 percent of the total proteins. The baculovirus recombinant expressed full-length VP4 protein was used to immunize animals. A high level of neutralizing antibody directed against parentalstrain SA11 virus was developed in the animals. The anti-vp4 antibody could block visible cytopathic effect (CPE) forming of SA11 virus in MA104 cells. Immunofluorescence test and Western blot also confirmed that the antibody could recognize specific antigen of rotavirus in infectious MA104 cells. The results suggest that VP4 protein expressed in a recombinant baculovirus has antigenicity and immunogenicity as well. It may be an important component in developing rotavirus recombinant and subunit vaccine.

Animals↗

PubMed1997

[Exogenous mtsl/p16 gene suppresses tumorigenicity of human gastric cancer cell line].

OBJECTIVE: To determine the effect on cell growth and tumorigenicity of mstl/p16 gene in human gastric cancer cell line. METHODS: mtsl/p16 gene vector was constructed and transfected into PAMC82 cells which retains down-regulated mtsl/p16 gene expression. Integration and expression of exogenous mtsl/p16 gene were confirmed by PCR, Northern blot, mRNA in situ hybridization and Western blot techniques. Cell morphology was observed in regular culture medium and tumorigenicity in nude mice. RESULTS: The growth of the cells transferred with mtsl/p16 gene (named as PAMCp16) was dramatically inhibited in nude mice as compared to that of the parental PAMC82 cells. Histologically, the tumor grown from PAMCp16 cells was much better differentiated than that from the parental ones. CONCLUSION: Tumorigenicity of a human gastric cancer cell line in nude mice can be inhibited by transduced exogenous mtsl/p16 gene. mtsl/p16 gene may have potential value in gene diagnosis and gene therapy.

Animals↗

PubMed1997

[Ten-case report on primary cervical lymphoma].

OBJECTIVE AND METHODS: Clinical feature, treatment and prognosis of primary cervical lymphoma: are retrospectively analysied. RESULTS: The disease is rare, comprising about 0.9% of all primary cervical malignancies. The average age was 43.6 years. Seven cases had history of familial carcinoma. The complaints: abnormal vaginal bleeding and/or vaginal discharge. The usual pattern of growth was endophytic or polypoid. By FIGO cervical cancer, staging system, there were 8/10 stage I b, 1/10 stage II b and 1/10 stage IV. Histologically all were NHL, B cell lesions(7/10) were the diffuse, cleaved or cleaved-noncleaved cell type. Combination of surgery and chemotherapy were used for 9 of these 10 patients. The follow-up period was 3-66 months. Only one patient had relapse 41 months after the treatment while, others (9/10) survived with no evidence of the disease. CONCLUSION: The prognosis is favorable if cervical lymphoma is discovered early and treated properly.

Adult↗