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Biomedical subjects

H Nguyen

Publications and source records attributed to H Nguyen.

At least 235 records · Page 13Linked to original sources
PubMed1987

Electron microscopic localization of a fucose-binding protein in acrosome reacted boar spermatozoa by the fucosyl-peroxidase-gold method.

In this study we have examined the behaviour and the localization of the fucose-binding protein (FBP) in boar spermatozoa during ionophore induced acrosome reaction (AR) by means of normal TEM and specimen preparation in toto. During early stages of AR the FBP is first localized at the border between equatorial segment and anterior acrosome. With the propagation of the AR the FBP is dramatically expressed and visible over the entire surface of the acrosome and equatorial segment. TEM pictures of this stages show that the FBP is associated with the OAM. At later stages of AR, when acrosomal ghost formation occur, the FBP is associated with the acrosomal ghost, and equatorial segment and to a very low degree also with the IAM. It is concluded from this data that the FBP is responsible for the specific binding of the ghost-sperm unit to the zona pellucida.

Acrosome↗
PubMed1987

Brain cellular and mitochondrial respiration in media of altered pH.

This study was designed to investigate the effects of altered pH on cellular aerobic energy metabolism in the immature and adult rat cerebral cortex. Cerebral cortical slice respiration was measured polarographically in acid and alkaline media. In separate experiments, the extracellular pH was changed by altering the HCO3- concentration or the intracellular pH and extracellular pH were changed by altering the CO2. Respiratory rates and oxidative phosphorylation in adult rat cerebral mitochondria also were measured in media with an altered pH. Increased intracellular pH inhibited respiratory rates in cortical slices from immature rats more than in tissue from adults. Decreasing the pH to 6.7 produced no changes in respiration in mature cortical slices and moderate inhibition of immature tissue respiration. In cerebral mitochondria, altered pH caused inhibition of State 3 respiration, respiratory control ratios, and ADP/O ratios. These changes were greater and occurred with smaller pH changes in the alkaline compared to the acid direction. From the results of these studies, we conclude that brain cellular respiration is not affected by moderate decreases in intracellular pH. With increased pH, there is inhibition of cellular and mitochondrial respiration, which may be the mechanism for the rise in lactic acid previously observed to result from hypocarbia in vivo.

Aging↗
PubMed1987

Anatomical basis of modern thoracotomies: the latissimus dorsi and the "serratus anterior-rhomboid" complex.

The latissimus dorsi and the "serrato-rhomboid" complex are the muscles most often involved in present-day thoracotomies for lung surgery. The present anatomic study emphasizes: the continuity between the serratus anterior and the rhomboid levator scapulae mass as a wide muscular sheet with a deep common fascia, extending the serrato-thoracic space (of Gillis) to the vertebral column as the rhomboserrato-thoracic space (the levator scapulae is situated higher up, above the ordinary thoracotomy); the presence of a "composite fascia" in the posterior angle between the seratus anterior and the rhomboid; the long costal attachment area and the presence of two differently oriented layers for the muscular digitations of the middle and inferior parts of the serratus anterior. With a rich vascular supply from multiple sources, the serratus anterior and latissimus dorsi are two large flat muscles with a single longitudinal nervous pedicle proceeding from the brachial plexus. To avoid esthetic (winged scapula) and functional sequelae, it is imperative to safeguard this single innervation as far as possible : by halting division of the serratus anterior before reaching its neurovascular pedicle in lateral or anterolateral thoracotomy, and by transecting the latissimus dorsi very low down in standard postero-lateral thoracotomy. The other muscles are simply freed and retracted.

Humans↗
PubMed1987

Nucleic acid sequence and oncogenic properties of the HZ2 feline sarcoma virus v-abl insert.

Hardy-Zuckerman 2 feline sarcoma virus (HZ2-FeSV), isolated from a multicentric feline fibrosarcoma is a replication-defective acute transforming feline retrovirus which originated by transduction of feline c-abl sequences with feline leukemia virus (FeLV) and is known to encode a 110-kilodalton gag-abl fusion protein with tyrosine-specific protein kinase activity (P. Besmer, W. D. Hardy, E. E. Zuckerman, P. J. Bergold, L. Lederman, and H. W. Snyder, Nature (London) 303:825-828, 1983). The nucleotide sequence of the abl segment in the HZ2-FeSV genome was determined and compared with the murine and human v-abl and c-abl sequences. The predicted transforming protein consists of 344 amino acids (aa) of FeLV gag origin, 439 aa of abl origin, and at least 200 aa of FeLV pol origin (p110gag-abl-pol). The 1,317-base-pair HZ2-FeSV v-abl segment (fv-abl) corresponds to 5' abl sequences which include the region known to specify the protein kinase domain. The 5' 189 base pairs of fv-abl correspond to 5' c-abl sequences not contained in Abelson murine leukemia virus (MuLV) v-abl. The mouse c-abl exon which contains these segments was identified, and its nucleotide sequence was determined. Comparison of the predicted amino acid sequence of fv-abl with those of Abelson MuLV v-abl and c-abl revealed five aa differences. The 5' junction between FeLV and abl was found to involve a preferred region in FeLV gag p30 (P. Besmer, J. E. Murphy, P. C. George, F. H. Qiu, P. J. Bergold, L. Lederman, H. W. Snyder, D. Brodeur, E. E. Zuckerman, and W. D. Hardy, Nature (London) 320:415-421, 1986). A six-base homology exists at the recombination site between the parental FeLV and the c-abl sequences. The 3' junction between fv-abl and FeLV pol predicts an in-frame fusion of fv-abl and FeLV pol. A transformed cell line containing a truncated gag-abl-pol protein, p85, that lacks most of the FeLV pol sequences was obtained by transfection of NIH 3T3 mouse cells. This result implies that the pol sequences of the p110gag-abl-pol protein are dispensable for fibroblast transformation. To assess whether the fv-abl segment specifies the unique biological properties of HZ2-FeSV, we constructed a Moloney MuLV-based version of HZ2-FeSV, Mo-MuLV(fv-abl), in which the fv-abl sequences were contained in a genetic context similar to that in HZ2-FeSV.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1987

[Absorbable synthetic clips and pulmonary excision. Our clinical experience].

Analysis of the first 50 clinical cases confirmed conclusions of experimental studies in large animals with respect to the use of absorbable synthetic clips formed of lactomer and polydioxanone. The advantages of clips when compared with ligatures include rapidity and simplicity of use and ease of insertion, even in regions difficult to approach surgically with the fingers. The advantages of clips of the absorbable synthetic type over conventional metallic material are: safety and reliability due to their locking system and the conservation of sufficient residual resistance, improved behavior in biologic media, radio-transparency and total inertia in magnetic fields compatible with postoperative radiation and modern medical imaging procedures (CT scan, IRM), and finally progressive resorption predictable by simple hydrolysis and then total disappearance after 6 to 7 months. With staplers of the TA and GIA type these clips make sutures and ligatures during lung resection surgery entirely automatic.

Absorption↗
PubMed1986

[The 2 key muscles in thoracotomy for excision of the lung. The latissimus dorsi and the levator scapulae muscles].

Anatomical data related to the thoracotomies performed most frequently in lung surgery are described in some detail: continuity between serratus anterior and levator scapulae as a vide muscular sheet possessing a common deep aponeurosis (thoracolumbar fascia) extending Gilis' space to the vertebral column as the levator scapulae-thoraci space; presence of a "composite aponeurosis" in the posterior angle between serratus anterior and levator scapulae, covering the 8th rib triangle or triangle of auscultation; long costal insertion area and presence of two differently orientated muscle layers for the digitations, particularly of apical bundle. Supplied by a rich vascularization of multiple sources, the serratus anterior and latissimus dorsi are two muscles with single longitudinal nerve pedicles derived from brachial plexus. It is certainly the denervation which is responsible for the distal atrophy of these muscles "sectioned on the right of the selected ribs" following conventional thoracotomy. To avoid esthetic and functional sequelae this innervation must be preserved as far as possible by: interrupting division of serratus anterior anterior to long thoracic nerve and avoiding inclusion of axillary border of latissimus dorsi during lateral thoracotomy; sectioning the latissimus dorsi as low as possible--the other muscles being simply freed and inclined--during lateral thoracotomy.

Arteries↗
PubMed1985

Secretion of the organic anion harmol sulfate from liver into blood. Evidence for a carrier-mediated mechanism.

In the liver, drugs with phenolic groups can be converted to sulfate or glucuronide conjugates and are then transported into bile or back into the bloodstream. The mechanism for transport of drugs and drug conjugates from the hepatocytes into the blood at the sinusoidal side of the cell are not well defined. In the case of carrier-mediated transport of these strongly polar conjugates, saturability of transport and mutual competition between structurally related compounds would be anticipated. This competitive aspect was investigated by using two organic anions, dibromosulfophthalein (DBSP) and harmol sulfate. The latter compound was generated by the hepatocytes from harmol, which was continuously infused into the rat in vivo and in isolated perfused rat livers. In addition we loaded the perfused rat livers with preformed harmol sulfate and studied its efflux rate to the perfusate as influenced by DBSP. In steady state, about 80% of harmol was sulfated and 20% was glucuronidated. Harmol sulfate was mainly excreted in the urine, the glucuronide was equally excreted in urine and bile. DBSP lowered the urinary excretion of harmol sulfate by about 30% which was due to a decrease in plasma concentration. However, renal clearance of harmol sulfate (3.2 +/- 0.2 ml/min) was unchanged. At the same time DBSP doubled the biliary clearance of harmol sulfate (1.0 +/- 0.1 and 2.2 +/- 0.2 ml/min in controls and DBSP studies respectively). DBSP decreased glucuronide excretion both in urine and bile. The increase in biliary output and decrease in urinary excretion of harmol sulfate is explained by competitive interaction between the organic anion DBSP and harmol sulfate at the sinusoidal level. Efflux experiments in single pass perfused isolated livers showed a clear decrease of harmol sulfate transport from liver into plasma by DBSP and provided evidence for such an inhibitory phenomenon (t 1/2 of efflux was 3.58 +/- 0.21 compared with 2.46 +/- 0.07 min for controls). These results indicate that organic anion transport from the hepatocyte into the blood stream is very likely carrier-mediated. A decrease in renal output of drug conjugates therefore may not only be due to a decrease in the conjugation process but also to a lower liver to blood transport rate which at the same time may produce a higher biliary output.

Alkaloids↗
PubMed1985

Shape and elasticity effects on erythrocyte electrostatic repulsion.

It is shown that the double-layer interaction between two symmetrically parallel red blood cells depends largely on their shape and elasticity. Various shapes are examined, including the realistic shape of a biconcave discocyte with an elastic membrane. It is found that changes in the shape and the elasticity of the erythrocyte may result in orders of magnitude differences in the forces and energies of pair interaction.

Elasticity↗
PubMed1985

Evidence for a fucose-binding protein in boar spermatozoa.

A fucose binding protein was detected in boar spermatozoa by means of a specifically developed modified enzyme-linked-lectin-assay using glycosylated peroxidase derivatives. The distribution of the fucose binding protein was assessed by means of fluorescence microscopy with fluoresceinyl-glycosylated peroxidase. Fucose binding was particularly prominent at the apical region of the sperm head. In order to gain more insight into the precise localization of the carbohydrate binding protein electron microscopical studies were performed using fucosyl peroxidase coupled to colloidal gold. In ultrathin sections as well as in specimens prepared in toto for TEM an intensive binding of fucosylperoxidase-colloidal gold was predominantly found at the apical part of the acrosome appearing as a crescent-like area. In some cases this binding pattern was replaced by a triangle-like intensive labelling at the equatorial segment as revealed clearly by specimens prepared in toto. By SDS-PAGE of the SDS-extractable sperm-proteins, followed by transblotting to nitrocellulose and visualization with the fucosylperoxidase by enzymatic amplification with 4-chloro-1-naphthol mainly one protein with the reduced molecular weight of approximately 53 kdal and some small proteins with apparent molecular weights less than 20 kdal was found to be responsible for the fucose-binding ability of porcine spermatozoa.

Acrosome↗
PubMed1985

Avoidance of GABA-containing diets by olfactory bulbectomized rats.

In order to test the importance of olfaction in the avoidance of GABA-containing diets by intact rats, olfactory bulbectomized and sham-operated control rats were allowed to choose between a low protein control diet and this diet supplemented with 2.5% GABA; the specificity of the response was examined by also testing for responses to other amino acids. Both groups of rats markedly avoided the GABA diet initially; the bulbectomized rats later tended to increase their intake of this diet. The bulbectomized rats chose similar amounts from the control diet and one supplemented with alanine whereas the control rats ultimately strongly preferred the latter diet. Both groups only moderately avoided a threonine-supplemented diet. The results suggest that (1) the odor of GABA is not critical in the avoidance of diets containing this amino acid; and (2) patterns of food selection from diets containing GABA differ from choices from diets containing other small neutral amino acids such as alanine or threonine.

Alanine↗