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Biomedical subjects

J Song

Publications and source records attributed to J Song.

At least 361 records · Page 20Linked to original sources
PubMed1993

Motor components of the trigeminal nerve and organization of the mandibular arch muscles in vertebrates. Phylogenetically conservative patterns and their ontogenetic basis.

The peripheral branching pattern of the mandibular ramus of the Vth cranial nerve and the organization of the trigeminal motor column are highly conserved in craniate phylogeny regardless of the vast modifications in attachments and structure of the mandibular arch musculature. Proximal, intermediate and distal series of mandibular nerve branches supply three major muscle groups and are in register with three neuronal populations of the trigeminal motor column. The adult branching pattern is established in response to the differentiation of mandibular muscles and is important in determining the organization of the motor nucleus of V. The innervation of the muscles of the mandibular segment of the head, and the location of motoneurons reflect their segmental origins and are reliable criteria for homologizing mandibular muscles among the craniates.

Anatomy, Comparative↗
PubMed1993

Regulation of hypothalamic preprogrowth hormone-releasing factor messenger ribonucleic acid expression in food-deprived rats: a role for histaminergic neurotransmission.

To determine the component(s) of dietary protein that regulates GH-releasing factor (GRF) synthesis, we measured hypothalamic prepro-GRF mRNA by solution hybridization/nuclease protection analysis in food-deprived rats refed protein-free diets (PF) supplemented with individual amino acids. Adult male Sprague-Dawley rats were allowed free access to food (Fed), food deprived for 72 h (FD), or FD then refed for 72 h with a normal (NF) diet, a protein-free (PF) diet, or PF diets containing tyrosine, tryptophan (Trp), glutamic acid, or histidine (His). Food-deprived rats displayed the expected 80% reduction in hypothalamic prepro-GRF mRNA. Upon refeeding, levels were normalized in rats refed a normal diet, but not in those refed a PF diet alone or with tyrosine, Trp, or glutamic acid. In contrast, prepro-GRF mRNA was restored to 70% of Fed values by a PF diet with His. Supplementing a PF diet with His was sufficient to maintain hypothalamic prepro-GRF mRNA expression, as 3 days of feeding replete rats with PF diet or PF diet with added Trp resulted in a 50% reduction in prepro-GRF mRNA, whereas levels were reduced 25% by feeding animals a PF diet with His. Groups of rats allowed free access to food were treated for 72 h with two daily injections of 100 mg/kg alpha-fluoremethylhistidine, a specific irreversible inhibitor of histidine decarboxylase, to determine if the effect of His on prepro-GRF mRNA depended on neural conversion to histamine. alpha-Fluoremethylhistidine-treated rats showed a 40% reduction in hypothalamic prepro-GRF mRNA, with no concomitant change in preproneuropeptide-Y or preprosomatostatin. These data indicate that decreased hypothalamic prepro-GRF mRNA in FD rats is due in part to the lack of dietary and provide clear evidence for a role of the histaminergic neural system in the regulation of hypothalamic GRF expression.

Animals↗
PubMed1993

Tissue distribution of somatostatin receptor subtype messenger ribonucleic acid in the rat.

The tissue distribution of mRNA encoding five somatostatin receptor subtypes, SSTR1, SSTR2, SSTR3, SSTR4, and SSTR5, was determined in adult rat tissues by solution hybridization/nuclease protection analysis using sequence-specific cRNA probes. In the central nervous system, SSTR1 and SSTR2 mRNA were expressed widely, with highest levels in hippocampus, hypothalamus, cortex, and amygdala and expression of both isoforms in cerebellum and spinal cord. Expression of SSTR3 was also widespread, occurring in all brain regions examined, with the highest level of expression in the cerebellum. SSTR4 mRNA was detected in most brain regions, with highest levels occurring in the hippocampus, cortex, and olfactory bulb. No detectable levels were found in cerebellum. SSTR5 showed a unique pattern of expression in the central nervous system, being found primarily in the hypothalamus and preoptic area. In peripheral tissues, high levels of SSTR1 and SSTR2 mRNA were found in pituitary and spleen. SSTR1 mRNA was also found in the heart and intestine, SSTR2 was detected in pancreas, and both isoforms were expressed in stomach. Expression of SSTR3 was noted in heart, liver, stomach, intestine, kidney, spleen, and pituitary. The patterns of expression were similar for SSTR4 and SSTR3 mRNA; however, SSTR4 was not expressed in liver. SSTR5 was expressed predominantly in the pituitary, but detectible levels were observed in spleen and intestine. Thus, the SSTR subtype mRNA showed both a tissue-specific and overlapping pattern of expression. Taken together with SSTR-specific signal transduction systems, this probably explains the diverse physiological actions of somatostatin.

Animals↗
PubMed1993

Influence of feeding schedule on chronopharmacological aspects of gentamicin in mice.

The effects of the time of day of drug administration on the subchronic toxicity and pharmacokinetics of gentamicin, as well as the role of feeding schedule on circadian rhythms, were investigated in mice. ICR male mice were housed in a light-dark (LD) cycle (12:12) with food and water ad libitum (ALF) or under a time-restricted feeding (TRF) schedule (feeding time: 8 h during the light phase) for 1 day or 14 days before drug administration. The animals were given a single subcutaneous dose of gentamicin 180 mg/kg for the kinetic studies and subcutaneous doses of gentamicin 180 mg/kg/day for 14 days or 220 mg/kg/day for 18 days for the subchronic toxicity studies. A significant dosing-time dependency was shown for mortality and body weight loss, with higher values at midlight and lower ones at the middark (p < 0.05). A significant circadian rhythm was also found for gentamicin kinetics in ALF mice, with the highest clearance at middark and the lowest one at midlight (p < 0.01). The kinetic rhythm of gentamicin coincided well with the toxicity rhythm of the drug. The TRF schedule had a marked influence on the rhythms of gentamicin kinetics and toxicity, showing lowest clearance and higher toxicity at middark. The rhythm of subchronic toxicity of gentamicin seems to be due, at least in part, to the rhythm in kinetics and is strongly influenced by the feeding schedule. Thus, the timing of dosing is an important factor in the kinetics and the subchronic toxicity of gentamicin administration in mice, and the manipulation of feeding schedule can modify the rhythm of the toxicity by changing the rhythm of gentamicin kinetics.

Animals↗
PubMed1993

A domestic cell bioreactor and its application in virus culture.

A cell culture bioreactor (CellCul-20) and its application in cell and virus culture are described in this paper. It has been evaluated with strict aseptic tests and one-year's operation shown that CellCul-20 bioreactor can keep its aseptic condition after being autoclaved. It can meet the requirement for the control of the main parameters for cell and virus culture and the finely adjustment of the main parameters to meet the changing conditions of the cultivation. A high cell density and a high level of virus titre were reached respectively for Vero cells and Japanese encephalitis virus (JEV) while they were cultured in this bioreactor. It is the first report on large-scale culture of JEV-infected Vero cells to prepare primary JEV vaccine. Some suggestions are made for the improvement of CellCul-20.

Animals↗
PubMed1992

Molecular cloning and functional expression of a brain-specific somatostatin receptor.

The PCR and conventional library screening were used to clone the brain-specific somatostatin receptor rSSTR-4 from a rat genomic library. The deduced amino acid sequence encodes a protein of 384 amino acids and displays structural and sequence homologies with members of the G protein-receptor superfamily. The amino acid sequence of rSSTR-4 is 60% and 48% identical to that of somatostatin receptors SSTR-1 and SSTR-2, respectively, two recently cloned subtypes. Competition curve analysis of the binding properties of the receptor transiently expressed in COS-1 cells revealed a higher apparent affinity for somatostatin 14 than for somatostatin 28. In contrast, the somatostatin analogs SMS 201-995, IM 4-28, and MK-678 failed to displace specific binding in transfected cells. These characteristics resemble the pharmacological binding properties of the previously described brain-specific somatostatin-receptor subtype. Examination of the tissue distribution of mRNA for rSSTR-4 revealed expression limited to various brain regions with highest levels in the cortex and hippocampus. Thus, based on the pharmacology and tissue localization of this receptor, we conclude that rSSTR-4 represents a brain-specific somatostatin receptor.

Amino Acid Sequence↗
PubMed1992

Refinement of dendritic arbors along the tonotopic axis of the gerbil lateral superior olive.

We have investigated the development of dendritic arbors in a central auditory nucleus in the Mongolian gerbil, the lateral superior olive (LSO). The morphology of these arbors has been shown to vary with tonotopic position in adults, with high frequency neurons having a more restricted field. In the present study, qualitative observations were made on horseradish peroxidase-filled neurons from animals 1-11 days postnatal, and quantitative results were obtained from Golgi-impregnated material from animals 10 days postnatal and older. The tonotopic position of each cell was computed as a percent of the total distance along the LSO. The dendritic arbors of high frequency neurons became spatially constrained along the frequency axis during the 3rd postnatal week, while those in the low frequency region retained a broader arborization into adulthood. This refinement was correlated with a decrease in total dendritic length and the number of branch points per neuron, particularly in the high frequency projection region. The distribution of octave bandwidths to which single LSO neurons responded in 13-16 day animals showed a similar course of maturation across the tonotopic axis: high frequency neurons responded to a larger number of octaves, and with greater variability, than those in adults. These data suggest that a specific alteration in dendrite morphology, which occurs after the onset of response to airborne sound, may contribute to adult frequency selectivity.

Animals↗
PubMed1992

Local and nonlocal curvature elasticity in bilayer membranes by tether formation from lecithin vesicles.

Bilayer membranes exhibit an elastic resistance to changes in curvature. This resistance depends both on the intrinsic stiffness of the constituent monolayers and on the curvature-induced expansion or compression of the monolayers relative to each other. The monolayers are constrained by hydrophobic forces to remain in contact, but they are capable of independent lateral redistribution to minimize the relative expansion or compression of each leaflet. Therefore, the magnitude of the expansion and compression of the monolayers relative to each other depends on the integral of the curvature over the entire membrane capsule. The coefficient characterizing the membrane stiffness resulting from relative expansion is the nonlocal bending modulus kr. Both the intrinsic (local) bending modulus (kc) and the nonlocal bending modulus (kr) can be measured by the formation of thin cylindrical membrane strands (tethers) from giant phospholipid vesicles. Previously, we reported measurements of kc based on measurements of tether radius as a function of force (Song and Waugh, 1991, J. Biomech. Engr. 112:233). Further analysis has revealed that the contribution from the nonlocal bending stiffness can be detected by measuring the change in the aspiration pressure required to establish equilibrium with increasing tether length. Using this approach, we obtain a mean value for the nonlocal bending modulus kr of approximately 4.1 x 10(-19)J. The range of values is broad (1.1-10.1 x 10(-19)J) and could reflect contributions other than simple mechanical equilibrium. Inclusion of the nonlocal bending stiffness in the calculation of kc results in a value for that modulus of approximately 1.20 +/- 0.17 x 10(-19)J, in close agreement with values obtained by other methods.

Biophysical Phenomena↗
PubMed1992

Nuclear deoxyribonucleic acid content measured by static cytometry: important prognostic association for patients with clinically localized prostate carcinoma treated by external beam radiotherapy.

To determine if relative nuclear deoxyribonucleic acid (DNA) content is an important prognostic parameter for patients with clinically localized prostate carcinoma treated by external beam radiotherapy, we performed static DNA cytometry on archival paraffin embedded prostate needle biopsy specimens obtained before treatment. DNA content was measured with the Zeiss IBAS 2000 Image Analyzer and the Feulgen staining method. Tumor samples from 65 patients with clinically localized carcinoma of the prostate treated with at least 6,000 cGy. from 1974 to 1980 were studied. Patients and tumors were divided into 2 groups: group 1 - 31 patients with relative DNA content less than 1.5 times normal and group 2 - 34 patients with relative DNA content greater than 1.5 times normal. The prostate cancer nonprogression rate at 10 years was 64% for group 1 and 11% for group 2. Prostate cancer cause specific survival at 10 years was 73% for group 1 and 20% for group 2. These differences are highly significant (p less than 0.0001). By contrast, stratification and analysis according to tumor clinical stage, Mayo histological nuclear grade or Gleason score proved not to be as significant. Cox multivariate analysis also identified DNA content as the most important independent variable for cancer specific survival and progression. Nuclear DNA content measured by static cytometry appears useful in identifying those patients with clinically localized prostate carcinoma who may have a favorable probability of long-term disease control by external beam radiotherapy.

Aged↗
PubMed1992

A comparison of various loading configurations of the proximal femur for the evaluation of reconstructive surgical procedures.

The study was designed to evaluate the effect of different loading configurations on stem and bone stresses in simulated total hip arthroplasty. The traditional experiment design of loading the model through the head of the prosthesis by the resultant joint force was compared with a more realistic model which included an abductor strap to simulate the abductor muscle force. In addition, an alternative experiment design was evaluated in which a loading arm was clamped directly on to the head of the prosthesis. The results show that loading the model by the resultant joint force not only changes the magnitude of the stresses but also the stress distribution compared to the abductor muscle model. The new experiment design closely approximates stresses seen in the abductor muscle model below the lesser trochanter. In the proximal region, the stresses are increased on the medial side and decreased on the lateral side. The advantages of the proposed loading model are: (a) easy and reproducible set-up and alignment is facilitated, (b) different positions of the femur (flexion, extension) can be simulated and (c) a more realistic stress distribution and magnitude is achieved.

Biomechanical Phenomena↗
PubMed1992

[An epidemiological analysis on the geographic factors of esophageal cancer].

The author collects the data of esophageal cancer mortality (1971-1973) of 78 counties in Hubei Province and the data of topography, climate, soil, rock formation and geochemical elements, including 40 suspected factors. The method of linear correlation and multiple stepwise regression are used for the comprehensive analysis of relation between the geographical factors and esophageal cancer. The result is that four factors metamorphic rock, zinc, copper, chromium are suspected factors. It suggests that the four factors will need future study.

China↗
PubMed1992

[Susceptibility of thirty-one species of mosquitoes to Romanomermis yunanensis].

A new species of Mermithidae was found parasitizing the larvae of Culex tritaeniorhynchus and Culex fatigans in Henan, China and then named Romanomermis yunanensis. Thirty-one species of Mosquitoes involving six genera have been tested for susceptibility to R. yunanensis and Culicinae mosquito have consistently been highly susceptible. At a 1:5 ratio of mosquito larvae to nematode juveniles, the parasitisms of Aedes aegypti, Ae. albopictus, Culex fatigans, Culex tritaeniorhynchus, Anopheles sinensts, Psorophora columbiae and Culesta inornata were 98.2%, 98.5%, 98.6%, 97.1%, 0%, 98.8%, and 99.0% respectively. R. yunanensis presented a phenomenon of retarted development in Anopheles maculatus, which remained at the parasitic stage both in the larvae and pupa of An. maculatus. The parasitism of An. dirus was 89.7%, but most (88.8%) parasitizing mermithids underwent melanization and died. The comparative susceptibility of some North American mosquitoes to R. yunanesis and R. culicivorax at a 1:5 infective ratio showed that both percentage infection and intensity of infection statistically supported the generalization that, under laboratory conditions, R. yunanesis is a more vigorous and aggressive parasite of Culicinae.

Aedes↗
PubMed1991

Structural analysis of the conformational domains involved in neutralization of bovine coronavirus using deletion mutants of the spike glycoprotein S1 subunit expressed by recombinant baculoviruses.

Two conformation-dependent neutralizing epitopes, A and B, have been mapped to the S1 subunit of the S spike glycoprotein of bovine coronavirus (BCV). In order to characterize the structure of these antigenic sites, we constructed a series of cDNA clones encoding deleted or truncated S1 derivatives and expressed the modified genes in insect cells using recombinant baculoviruses. Monoclonal antibodies directed against epitopes A and B recognized only the mutant S1 polypeptides containing amino acids 324-720, as demonstrated by immunoprecipitation and Western blot analysis in the absence of beta-mercaptoethanol. In addition, two domains within this region were identified and only mutants containing both domains were immunoreactive, indicating that both were critical in the formation of the antigenic determinants. One domain was localized between residues 324 and 403 and the other at residues 517-720. Deletion of either domain inhibited extracellular secretion of the mutant proteins whereas mutants containing both or none of the domains were secreted efficiently. This observation suggests a vital function of the native conformation of the S1 protein in both antigenic structure and intracellular transport. Antigenic determinants A and B were not distinguished, but these determinants appeared to require both domains for epitope formation. Our results suggest that the antigenic determinants formed by two domains are likely associated with the probable polymorphic region of the BCV S1 subunit.

Animals↗
PubMed1991

Electron microscopic studies of the endoplasmic reticulum in whole-mount cultured cells fixed with potassium permanganate.

A method for visualizing the endoplasmic reticulum and other membrane organelles in whole-mount cells with a standard, 60-kV transmission electron microscope has been developed. By use of a new formulation of potassium permanganate as a fixative, intracellular membranes were preserved and stained, while cytosolic proteins were digested, giving a pattern of membranous organelles against a clear background, suitable for transmission EM of whole-mount cells at 60 kV. Mitochondria, lysosomes, and ER were clearly visible in whole-mount cells fixed by this method. We have employed this technique to examine the organization of the ER in a variety of different cell lines. This method also allowed visualization of the three-dimensional organization, relationships, and fine structure of mitochondria. With prolonged permanganate fixation, mitochondrial cristae were clearly visible in whole-mount cells. This method was also useful for fixation and staining of thin sections, and allowed examination of thicker sections than previously possible, thus giving improved imaging of organelle relationships and fine structure. Using this method, we have examined the ER, mitochondria, and Golgi in thin section.

3T3 Cells↗
PubMed1991

Effects of dietary selenium and fish oil (MaxEPA) on arachidonic acid metabolism and hemostatic function in rats.

This study investigated whether hemostatic function can be modified by both the consumption of fish oil and the level of dietary selenium. Male Sprague-Dawley rats were fed for 8 wk semipurified diets containing 7% corn oil (by wt) or 5.5% fish oil (MaxEPA) plus 1.5% corn oil with or without selenium supplementation. Consumption of the four diets caused no difference in weight gain, food intake or plasma malondialdehyde content. The selenium-supplemented rats had significantly higher levels of selenium and glutathione peroxidase activity in plasma. Fish oil feeding decreased ADP-induced platelet aggregation and increased bleeding time. The level of dietary selenium and type of oil interacted to influence the production of 6-keto-prostaglandin F1 alpha: more was produced when corn oil was fed in the selenium-deficient diets. These data suggest that the effect of dietary selenium on hemostatic function and the production of eicosanoids is minor.

Administration, Oral↗