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Biomedical subjects

C Huynh

Publications and source records attributed to C Huynh.

At least 19 recordsLinked to original sources
PubMed2001

Comparative effects of red blood cell transfusion and increasing blood flow on tissue oxygenation in oxygen supply-dependent conditions.

Red blood cell (RBC) transfusion is usually administered to improve oxygen delivery (DO(2)) in order to sustain tissue oxygen demand. However, this practice is not supported by firm clinical or experimental data. Using a randomized two-period crossover design, this study compared the efficacy of "fresh" RBC transfusion and increased blood flow to restore tissue oxygenation in oxygen supply-dependent conditions. In 12 ketamine-anesthetized mongrel dogs submitted to nonpulsatile normothermic cardiopulmonary bypass, DO(2) was reduced by a progressive decrease in pump flow. DO(2) dependency was defined as an O(2) uptake (V O(2)) decrease by more than 15% from baseline value. Then, intervention consisted of a 40% increase in DO(2) obtained either by transfusion of "fresh" dog's RBC (stored < 3 d) or by increase in pump flow. Animals received both interventions sequentially in a random order, while O(2) saturation was maintained constant. In O(2) supply-dependent conditions, rising pump flow from 1.6 +/- 0.4 to 2.7 +/- 0.7 L/ min increased DO(2) from 5.4 +/- 1.1 to 9.0 +/- 1.3 ml/kg/min (p < 0.01) and V O(2) from 3.5 +/- 0.4 to 4.1 +/- 0.5 ml/kg/min (p = 0.02). "Fresh" RBC transfusion, which increased the hemoglobin concentration from 6.4 +/- 0.9 to 11.1 +/- 1.3 g/dl, increased DO(2) from 5.4 +/- 1.2 to 9.0 +/- 1.4 ml/kg/min (p < 0.01) and V O(2) from 3.6 +/- 0.4 to 4.1 +/- 0.5 ml/kg/min (p = 0.02). There was no difference in V O(2) resulting from both interventions. In oxygen supply-dependent conditions, "fresh" RBC transfusion and increased blood flow are equally effective in restoring tissue oxygenation.

Animals↗
PubMed2000

Identification and characterization of a 315-base pair enhancer, located more than 55 kilobases 5' of the apolipoprotein B gene, that confers expression in the intestine.

We recently reported that an 8-kilobase (kb) region, spanning from -54 to -62 kb 5' of the human apolipoprotein B (apoB) gene, contains intestine-specific regulatory elements that control apoB expression in the intestines of transgenic mice. In this study, we further localized the apoB intestinal control region to a 3-kb segment (-54 to -57 kb). DNaseI hypersensitivity studies uncovered a prominent DNaseI hypersensitivity site, located within a 315-base pair (bp) fragment at the 5'-end of the 3-kb segment, in transcriptionally active CaCo-2 cells but not in transcriptionally inactive HeLa cells. Transient transfection experiments with CaCo-2 and HepG2 cells indicated that the 315-bp fragment contained an intestine-specific enhancer, and analysis of the DNA sequence revealed putative binding sites for the tissue-specific transcription factors hepatocyte nuclear factor 3beta, hepatocyte nuclear factor 4, and CAAT enhancer-binding protein beta. Binding of these factors to the 315-bp enhancer was demonstrated in gel retardation experiments. Transfection of deletion mutants of the 315-bp enhancer revealed the relative contributions of these transcription factors in the activity of the apoB intestinal enhancer. The corresponding segment of the mouse apoB gene (located -40 to -83 kb 5' of the structural gene) exhibited a high degree of sequence conservation in the binding sites for the key transcriptional activators and also exhibited enhancer activity in transient transfection assays with CaCo-2 cells. In transgenic mouse expression studies, the 315-bp enhancer conferred intestinal expression to human apoB transgenes.

Animals↗
PubMed1999

Expression of the human cholesterol 7alpha-hydroxylase gene in transgenic mice.

We have generated transgenic mice expressing human CYP7A1 transgenes. Only 1.5 kilobases (kb) of 5' upstream sequence and 6.5 kb of 3' sequence were sufficient for hepatic transcription of the transgenes. However, the 5' end segment alone was not sufficient to direct liver expression, suggesting that additional hepatic regulatory elements reside in the 3' extension or within introns. The level of expression of these transgenes was low in comparison to the levels of the endogenous mouse CYP7A1 mRNA. To generate mice expressing higher levels of CYP7A1 mRNA, we injected a large human genomic PAC clone, extending up to -105 kb 5' of the structural gene and about 50 kb 3' of the gene. These transgenic mice expressed CYP7A1 mRNA at higher levels, suggesting that additional hepatic regulatory elements are found either 5' of -1520 or beyond 6.5 kb 3' of the gene.

Animals↗
PubMed1999

Peripheral neuropathy in systemic lupus erythematosus.

The prevalence of clinically apparent peripheral neuropathy in systemic lupus erythematosus is reported to be between 2% to 18%. The purpose of this prospective case-control study was to determine the prevalence of peripheral neuropathy (PN) using electrodiagnostic criteria. Subgroup analysis was performed to determine whether PN correlated with disease activity, renal involvement, or serum immune markers. Fifty-four systemic lupus erythematosus patients and 30 controls were recruited in the study. The right median, ulnar, peroneal, tibial, and sural sensory and motor nerve conduction studies were obtained. PN in our study was defined as any abnormal values in motor and sensory distal latency, sensory action potential, motor action potential, or conduction velocity affecting 2 or more nerves. Of the 54 patients studied, PN was present in 15 patients (27.8%) of which 4 were symptomatic. There was a significant correlation between PN and anti-SM antibody, and there was a trend showing decreased motor and sensory action potential amplitudes in our systemic lupus erythematosus group compared to the controls. This observation was also seen in an active disease group when compared to those with inactive disease. The amplitude of the action potential was more often affected than the distal latency, and sensory nerves were more susceptible than motor nerves. The sural sensory action potential amplitude appears to be the most sensitive indicator of PN which may be used as an index to monitor disease activity.

Adolescent↗
PubMed1997

Active and alpha-1 proteinase inhibitor complexed leukocyte elastase levels in crevicular fluid from patients with periodontal diseases.

Human leukocyte elastase is present in large amounts in the crevicular fluid of patients with periodontal disease and was considered as a putative biological marker of the evolution of such diseases. The aim of this work was to measure spectrophotometrically amounts of active elastase (AE) and elastase complexed to alpha 1 proteinase inhibitor (E-alpha 1-PI) in gingival crevicular fluid obtained, from patients suffering from rapidly progressive periodontitis (RPP group) or adult periodontitis (AP group) with different probing depths (3 to 5 mm and > 6 mm). AE and E-alpha 1-PI concentrations were negligible in healthy individuals. AE, but not E-alpha 1-PI, concentration appears to vary significantly with the probing depth in patients suffering either from rapidly progressive or adult periodontitis. No correlations were found between levels of AE and E-alpha 1-PI in the different groups of patients. AE concentration seems to be a marker of periodontal diseases in relation with probing depth.

Adult↗
PubMed1994

An animal model for the assessment of gingival lesions.

A model of gingival inflammation was performed in Sprague-Dawley rats weighing 180-200 g. Mechanical bamboo stick-induced injury was inflammatory when bacteria contaminated the sticks. Bacteria were first obtained from gingival fluid collected from a patient with adult periodontitis. Another strain from Institut Pasteur (IP 6444) induced similar inflammation. Inflammation was then quantified 10 days later by means of elastase assays performed in gingival extracts. In parallel, elastic structures were observed and elastic fibers were quantified by automated image analysis. This technique of "impaction" was able to induce a gingival inflammatory reaction characterized by a significant increase of gingival elastase content, infiltration of gingival tissues by elicited cells, and gingival elastic fiber breakdown. These parameters were correlated, and measurement of one of them might be useful for pharmacological studies applied to the treatment of periodontal lesions. An example of results obtained from animals treated by heparine was shown.

Animals↗
PubMed1992

A survey of expressed genes in Caenorhabditis elegans.

As an adjunct to the genomic sequencing of Caenorhabditis elegans, we have investigated a representative cDNA library of 1,517 clones. A single sequence read has been obtained from the 5' end of each clone, allowing its characterization with respect to the public databases, and the clones are being localized on the genome map. The result is the identification of about 1,200 of the estimated 15,000 genes of C. elegans. More than 30% of the inferred protein sequences have significant similarity to existing sequences in the databases, providing a route towards in vivo analysis of known genes in the nematode. These clones also provide material for assessing the accuracy of predicted exons and splicing patterns and will lead to a more accurate estimate of the total number of genes in the organism than has hitherto been available.

Animals↗
PubMed1992

A genetic mapping system in Caenorhabditis elegans based on polymorphic sequence-tagged sites.

We devised an efficient genetic mapping system in the nematode Caenorhabditis elegans which is based upon the differences in number and location of the transposable element Tc1 between the Bristol and Bergerac strains. Using the nearly completed physical map of the C. elegans genome, we selected 40 widely distributed sites which contain a Tc1 element in the Bergerac strain, but not in the Bristol strain. For each site a polymerase chain reaction assay was designed that can distinguish between the Bergerac Tc1-containing site and the Bristol "empty" site. By combining appropriate assays in a single reaction, one can score multiple sites within single worms. This permits a mutation to be rapidly mapped, first to a linkage group and then to a chromosomal subregion, through analysis of only a small number of progeny from a single interstrain cross.

Animals↗
PubMed1992

Gingival crevicular fluid of patients with gingivitis or periodontal disease: evaluation of elastase-alpha 1 proteinase inhibitor complex.

Elastase-alpha 1 proteinase inhibitor (E alpha 1PI) concentrations were assessed in gingival crevicular fluids and evaluated in relation to the clinical signs of periodontal disease. 7 gingivitis patients (group G), 38 patients with adult periodontitis and clinically stable lesions (group AP), 21 patients with rapidly progressive periodontitis and clinically stable lesions (group RPP) and 11 patients with either adult periodontitis or rapidly progressive periodontitis and clinically progressive lesions (group Pr) were studied. 6 healthy subjects served as the control group (group H). Significantly differences were observed in the E alpha 1PI concentration between the healthy, gingivitis, clinically stable periodontitis and clinically progressive periodontitis group. In the control group, no E alpha 1PI was detected. Groups G, AP and RPP showed mean E alpha 1PI concentrations of 10.95 +/- 4.96 micrograms/ml, 35.55 +/- 18.64 micrograms/ml and 38.56 +/- 20.89 micrograms/ml, respectively. In these groups, high enzyme levels were correlated with clinical signs of inflammation. The highest E alpha 1PI levels were observed in the clinically progressive lesions. However, they were not necessarily associated with bleeding on probing or clinical evidence of inflammation. These data suggest that a significant increase in crevicular E alpha 1PI levels may be an early manifestation of a progressive or potentially progressive periodontal lesion.

Adult↗
PubMed1991

[Bacterial contamination, familial occurrence and periodontal disease].

The pathogenesis of the various periodontal diseases cannot only be explained on the basis of the relationship of specific bacteria to the clinical features of the disease. The microbiologic examination of various members of the same family, either by culturing or by the use of the DNA probe often showed similarities among several individuals in the same family. This could be accounted for on the basis of bacterial transmission or by contamination. These observations suggest the incidence of familial and genetic factors in the etiology of some forms of periodontitis.

Adult↗
PubMed1990

[Periodontal diseases and antibacterial drug treatment].

Recent data concerning the bacteriology of periodontal diseases justify the use of antibacterial drugs. In advanced or resistant forms of the disease, the standard treatments are in fact insufficient. The antibacterial agents advocated include systemic antibiotics and local antiseptics. These products may be used separately or in combination. But, this antibacterial treatment remains a complementary option and cannot replace conventional treatments.

Adult↗