Biomedical subjects

H Truong

Publications and source records attributed to H Truong.

18 recordsLinked to original sources

PubMed2003

Identification of dorsal root ganglion neurons that innervate the common bile duct of rats.

Pain originating in the bile duct is common and many patients who have suffered from it report that it is one of the most intense forms of pain that they have experienced. Many uncertainties remain about the mechanisms underlying pain originating in the bile duct. For example, the dorsal root ganglion (DRG) neurons that give rise to the sensory innervation of the common bile duct (CBD) have not been identified and examined in any species. The goal of the present study was to determine the number, distribution, and size of DRG neurons that innervate the CBD in rats. Injections of WGA-HRP or CTB-HRP were restricted to the lumen of the bile duct. Injections of WGA-HRP labeled a mean number of about 500 DRG neurons bilaterally throughout all thoracic and upper lumbar levels. Injections of CTB-HRP labeled smaller numbers of DRG neurons. Application of colchicine onto the surface of the CBD reduced the number of cells labeled following injections of WGA-HRP into the lumen of the CBD by roughly 86%, suggesting that tracer had not spread in large amounts out of the CBD and labeled afferent fibers in other tissues. Approximately 85% of the neurons labeled with WGA-HRP had cell bodies that were classified as small; the remainder were medium in size. Injections of CTB-HRP labeled cell bodies of varying sizes, including a few large diameter cell bodies. These results indicate that a large number of primarily small DRG cells, located bilaterally at many segmental levels, provide a rich innervation of the common bile duct.

Animals↗

PubMed2000

Essential role for the dsRNA-dependent protein kinase PKR in innate immunity to viral infection.

The double-stranded (ds) RNA-dependent protein kinase PKR is considered to play an important role in interferon's (IFN's) response to viral infection. Here, we demonstrate that mice lacking PKR are predisposed to lethal intranasal infection by the usually innocuous vesicular stomatitis virus, and also display increased susceptibility to influenza virus infection. Our data indicate that in normal cells, PKR primarily prevents virus replication by inhibiting the translation of viral mRNAs through phosphorylation of eIF2alpha, while concomitantly assisting in the production of autocrine IFN and the establishment of an antiviral state. These results show that PKR is an essential component of innate immunity that acts early in host defense prior to the onset of IFN counteraction and the acquired immune response.

Animals↗

PubMed1997

Developmental expression of GABA(A) receptor subunit and GAD genes in mouse somatosensory barrel cortex.

In situ hybridization histochemistry with radioactive cRNA probes was used to study patterns of gene expression for alpha1, alpha2, alpha4, alpha5, beta1, beta2, and gamma2 subunit mRNAs of typeAgamma aminobutyric acid (GABA(A)) receptors and for 67-kDa glutamic acid decarboxylase (GAD67) mRNA in mouse barrel cortex during the period (postnatal days 1-12; P1-P12) when thalamocortical innervation of layer IV barrels is occurring. The alpha1, beta2, and gamma2 subunit mRNAs increased substantially with age, especially in layers V and VI, and throughout the period studied, invariably had the same laminar-specific patterns of expression. All three mRNAs were highly expressed in the dense cortical plate at P1. In layer IV after differentiation of barrels, they were expressed in cells of both barrel walls and hollows but especially in the walls. The alpha2, alpha4, alpha5, and beta1 subunit mRNAs were expressed at lower levels and had different laminar patterns of distribution; alpha2 and alpha4 showed switches between layers over time; alpha5 was invariably associated with the subplate or its derivative, beta1 with layer IV. Levels of alpha2 mRNA did not change over time; alpha4 and beta1 mRNAs increased and alpha5 decreased. GAD67 mRNA was highest in layer I at P1 and progressively increased in other layers. These results suggest that postnatal development of GABA(A) receptors is mainly directed at the production of receptors assembled from alpha1, beta2, and gamma2 subunits, with beta1 contributing in layer IV. Other subunits may be associated with receptors involved in trophic actions of GABA during development and may give GABA(A) receptor-mediated responses in the developing cortex their particular physiological profile.

Animals↗

PubMed1997

A rule-based expert system for the automatic classification of DNA "ploidy" histograms measured by the CAS 200 image analysis system.

DNA "ploidy" histogram interpretation is one of the most important sources of variation in DNA image cytometry and is influenced by multiple technical factors such as scaling, selection of peaks, and variable classification criteria. A rule-based expert system was developed to automate and eliminate subjectivity from this interpretative process. Ninety-eight Feulgen stained histologic sections from patients with breast, colon, and lung cancer were measured with the CAS 200 image analysis system (Becton Dickinson, Santa Clara, CA); they included diploid (n = 42), aneuploid (n = 46), tetraploid (n = 7), and multiploid (n = 3) examples. The data was converted from listmode format into ASCII with the aid of CELLSHEET software (JVC Imaging, Elmhurst, IL). Individual microphotometric nuclear measurements were sorted to one of 64 bins based on DNA index. The 64 bins were then divided into 5 semi-arbitrarily defined ranges: hypodiploid, diploid, aneuploid, tetraploid, and hypertetraploid. The nuclear percentages in each range were calculated with EXCEL 4.0 (Microsoft, Redmond, WA). The histograms were divided into 2 equal sets: training and testing. The data from the training set were used to develop 16 IF-THEN rules to classify the histograms into diploid, aneuploid, or tetraploid. A macro was programmed in EXCEL to automate all these operations. The rule-based expert system classified correctly 45/50 histograms of the training set. Two tetraploid histograms were classified as aneuploid. Three multiploid histograms were classified as tetraploid. All histograms in the testing set were correctly classified by the expert system. The potential role of rule-based expert system technology for the objective classification of DNA "ploidy" histograms measured by image cytometry is discussed.

Automation↗

PubMed1997

Effect of various acute 60 Hz magnetic field exposures on the nocturnal melatonin rise in the adult Djungarian hamster.

Acute exposure to a 1 Gauss 60 Hz magnetic field for 15 min beginning 2 hr before darkness delays and blunts the nighttime melatonin rhythm in some but not all studies. To determine whether other exposure parameters (dose, mode, or time) influence the nocturnal melatonin rise, adult Djungarian hamsters reared in long days (16L:8D, lights off at 1000-1800 hr) were acutely exposed to a 60 Hz continuous magnetic field (15 min of 1 or 0.1 Gauss) beginning 4 hr before or 4 hr after lights off. Other hamsters were exposed to a 60 Hz intermittent magnetic field (15 or 60 min of a 1 Gauss field, 1 min on then 1 min off) between 1 and 2 hr before lights off. In sham-exposed controls, i.e., hamsters simultaneously placed in an adjacent coil system but without current, pineal and serum melatonin concentrations increased from a low baseline (1 hr after lights off) to concentrations that were typical of the nighttime peak by 3 hr after darkness. Acute exposure to the 0.1 or 1 Gauss continuous magnetic field for 15 min at either 4 hr before or 4 hr after lights off did not disrupt the nocturnal rise in pineal or serum melatonin. Similarly, onset of the melatonin rhythm was not suppressed by intermittent magnetic field exposures compared to that in sham controls. Thus, several magnetic field exposure paradigms failed to alter the rising phase of the melatonin rhythm in pineal gland content or in circulation. These findings indicate that the biological clock mechanism that mediates photoperiodic time measurement in this seasonally breeding rodent is resistant to a variety of acute continuous or intermittent magnetic field exposures.

Animals↗

PubMed1996

Photoperiod control of the melatonin rhythm and reproductive maturation in the juvenile Djungarian hamster: 60-Hz magnetic field exposure effects.

Photoperiodic regulation of the melatonin rhythm was studied in juvenile Djungarian hamsters to test the hypothesis that magnetic field (MF) exposures disrupt sexual maturation. Juveniles in long or short days postweaning were exposed each day to a 1-gauss 60-Hz MF (15 min, 2 h before lights-off). At age 25 days, nighttime duration of the melatonin rise in the pineal gland and circulation of sham-treated controls (adjacent coil system but without current) was < 8 h in long-day juveniles and nearly 13 h in short-day hamsters. This is the first study in juveniles to demonstrate that the melatonin rhythm duration is regulated by photoperiod and that reproductive development was not disrupted by daily or acute MF exposures; puberty was initiated in long days but arrested by short days, irrespective of MF treatment. In a replicate study, MF exposures had no effect on the duration of increased melatonin. In the initial and the replicate study, amplitude differences in the nighttime pineal or serum melatonin rise possibly reflected inherent variability in repetitive melatonin rhythms. In addition, effects of daily melatonin injections to arrest puberty were not blocked by daily MF exposures. The findings support the conclusion that MF exposures fail to disrupt photoperiodic time measurement or the neuroendocrine mechanism regulating reproductive maturation in the juvenile Djungarian hamster.

Animals↗

PubMed1995

Mechanism of colonic permeation of inulin: is rat colon more permeable than small intestine?

BACKGROUND/AIMS: Colonic epithelium is considered to be relatively tight. The colonic "pore" diameter is 6 A; therefore, colonic epithelium has generally been considered to be impermeable to hydrophilic probes with a cross-sectional diameter of > 6 A. This study examined whether rat colon is permeable to inulin, a large hydrophilic macromolecule having a molecular weight of 5000 g/mol and a cross-sectional diameter of 15 A (hydration diameter, 20 A). METHODS: The colonic permeation of inulin (10 mumol/L) in vivo was investigated by perfusion of rat colonic segments. RESULTS: There was significant colonic permeation of inulin, but tissue retention of inulin was low. The net colonic flux of inulin was strongly dependent on net water flux, showing a strong solvent drag effect. Addition of 16,16-dimethyl prostaglandin E2 decreased water flux with a corresponding decrease in inulin flux; this process seemed to be mediated by 5'-cyclic adenosine monophosphate because both the phosphodiesterase inhibitor aminophylline and dibutyryl adenosine 5'-cyclic adenosine monophosphate decreased water and inulin flux in a parallel manner. Chenodeoxycholic and taurocholic acids decreased net mucosal-to-serosal water flux but increased inulin flux. The net colonic permeation rate of inulin was higher than the small intestinal permeation rate. CONCLUSIONS: Rat colon is permeable to inulin. The higher net colonic permeability may be caused by differences in mucosal surface, permselectivity, solvent drag effect, and differences in net water fluxes of the colon and small intestine.

16,16-Dimethylprostaglandin E2↗

PubMed1995

Neural networks as an aid in the diagnosis of lymphocyte-rich effusions.

Neural network (NN) technology was applied to digital image analysis data for 112 Papanicolaou-fixed and -stained smears of lymphocyte-rich effusions (LREs). The smears were analyzed with an inexpensive image analysis system assembled in our laboratory. Several models were developed using backpropagation NN development software in an effort to optimize classification of the LREs as reactive lymphocytosis or malignant lymphoma and to analyze the effects of various parameters on classification rates. The greatest specificity and sensitivity of LRE classification were achieved with NN models that consisted of 7 input neurons, including 5 morphometric and 2 densitometric variables, 10 hidden-layer neurons and 1 output neuron. This NN architecture with a sigmoidal transfer function provided a true cross-validation rate of 89.3% of testing data, with a sensitivity of 76.9%, specificity of 93.0% and shrinkage of 10.7%. The same NN architecture with a step transfer function provided a true cross-validation rate of 95.3%, sensitivity of 85.7%, specificity of 97.6% and shrinkage of 0%. The effects of various parameters, such as network size, shrinkage and ratio of sample size to input layer size, on NN accuracy are discussed.

Ascitic Fluid↗

PubMed1991

Is the small intestinal epithelium truly "tight" to inulin permeation?

In this study, we evaluated the "leakiness" of intestinal epithelium through examination of small intestinal absorption of inulin in vivo by perfusing rat jejunum with 10 microM inulin. In physiological conditions, we found significant absorption of inulin at a rate of 44.6 nmol.100 cm-1.h-1 or absorption of 14.7%.100 cm-1.h-1 of the amount perfused. Increasing water flux by changing the luminal osmolarity resulted in linear (y = 31.1 + 2.4x, r = 0.97) increase in absorption of inulin, indicating a significant convective component of inulin absorption. There was large permeation of inulin at net water secretion and at zero net water fluxes (31.1 nmol.100 cm-1.h-1), indicating significant absorption of inulin by diffusive movement as well. The small intestinal tissue retention of inulin occurred rapidly within the first 15 min of perfusion, and the total tissue retention remained unchanged thereafter at approximately 10.8 nmol/100 cm. 16,16-Dimethylprostaglandin E2 decreased water flux, whereas cyclooxygenase inhibitors, indomethacin and acetylsalicylate, increased water flux. Inulin absorption closely paralleled changes in water flux induced by these agents. Taurocholate also caused parallel decrease in water and inulin absorption. Varying the resistance of unstirred water layer with changing luminal flow rate, the addition of mucolytic agent acetylcysteine, or alterations of luminal pH did not affect water or inulin absorption. We conclude that inulin permeates the small intestinal epithelium in significant amounts under normal physiological conditions, presumably through the paracellular pathways utilizing aqueous channels.

16,16-Dimethylprostaglandin E2↗

PubMed1975

[Standardization of "exchange" techniques to measure estradiol receptors in extracts exposed to biospecific adsorbants].

The measurement of the binding of steroid hormone receptors to biospecific adsorbants requires the development of "exchange" techniques. Two types of techniques based on the principle of differential dissociation were standardized: solid phase exchange with hydroxylapatite and liquid phase exchange with adsorption of the ligand to charcoal dextran. In both cases, binding of oestradiol to its receptor was measured in calf uterine cytosol extracts. Results obtained by both techniques were comparable. The half-times of the oestradiol-receptor complex dissociation determined from exchange kinetics are on the same order as those obtained by direct methods used in previous studies.

Animals↗

PubMed1974