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Biomedical subjects

Y Han

Publications and source records attributed to Y Han.

At least 307 records · Page 17Linked to original sources
PubMed1993

Effects of sex, heat stress, body weight, and genetic strain on the dietary lysine requirement of broiler chicks.

Experiments were carried out to investigate the effects of sex, heat stress (37 C), body weight (heavy and light within strain), and strain of chicks on the dietary lysine requirement of chicks during 8 to 22 days posthatching. A lysine-deficient basal diet (.64% total lysine, 23% CP, 3,200 kcal ME(n)/kg) containing corn, feather meal, and soybean meal was supplemented with graded levels of L-lysine.HCl to produce growth response curves. The lysine-deficient diet contained .52% true digestible lysine as determined with a precision-fed cecectomized adult cockerel assay (Experiment 1). Hubbard x Hubbard chicks were used in Experiment 2 and New Hampshire x Columbian crossbred chicks were used in Experiments 3 and 4. Experiment 2 compared lysine requirements of male and female chicks. Weight gains between sexes were similar when diets were deficient in lysine, but males grew faster than females when lysine-adequate diets were fed. Male chicks required a higher level of dietary lysine than females for both maximal weight gain and feed efficiency. Also, regardless of sex, the lysine requirement (percentage of diet) for maximal feed efficiency was higher than that for maximal weight gain. In Experiment 3, heat stress reduced weight gain and feed intake of both males and females by about 22%, and it increased the lysine requirement of female but not male chicks. In Experiment 4, light and heavy chicks were selected from male and female populations. Heavy and light chicks exhibited the same dietary lysine requirement for maximal growth. However, the lysine requirement for maximal feed efficiency was higher for heavy birds than for light birds.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1993

Effects of excess methionine or lysine for broilers fed a corn-soybean meal diet.

Three experiments were conducted to examine the consequences of over-supplementing DL-Met or L-Lys (as L-Lys.HCl) in diets for chicks fed a corn-soybean meal diet (23% CP, 3,200 kcal MEn/kg, .2% supplemental Met) during 1 to 3 wk posthatching. New Hampshire x Columbian male chicks were used in Experiments 1 and 2 and Hubbard x Hubbard males were employed in Experiment 3. The basal diet was supplemented with .5, 1.0, 2.0, or 4.0% DL-Met, or .4, .8, 1.6, or 3.2% L-Lys in Experiment 1. Weight gain, feed intake, and feed efficiency decreased linearly at supplemental levels of DL-Met between 1.0 and 4.0%. Weight gain of chicks fed diets with supplemental L-Lys levels greater than 1.6% was less than that of chicks fed the basal diet, but feed efficiency was not significantly affected. Adding K2CO3 to the diets containing 1.6 or 3.2% added L-Lys did not improve performance. Experiment 2 evaluated the effect of 1) adding 1.0% Gly or 1.0% L-Thr to the diet supplemented with 2.0% DL-Met; and 2) adding NaHCO3 to the high-Lys diets in order to buffer the excess chloride provided by L-Lys.HCl. Addition of these amino acids or buffer ameliorated but did not totally correct the negative effects of excess Met or Lys. Experiment 3 examined the tolerance of commercial broilers to supplemental DL-Met or L-Lys levels of .5 or 1.0%. Weight gain and feed efficiency were not affected by these excesses, but feed intake was reduced at the 1.0% level of inclusion of either amino acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1993

[An experimental study of compound implants made of vein and nerve for repairing peripheral nerve gaps].

The effect of peripheral nerve regeneration in bridging short gaps of peripheral nerve with non-neural material is reliable, but rather disappointed in long gaps. In this study, we bridged a 3.0 cm long peroneal nerve defect in rabbits only with an autogenous vein. no nerve regeneration was found 22 weeks after operation. In the experimental group, we divided the vein into two parts, and a 0.3 cm long free nerve segment was sutured between them, which was then used to bridge a peroneal nerve gap with the same length as above definite nerve regeneration was demonstrated by electrophysiological, histological examination and HRP tracing. Therefore, the effect was improved significantly with the addition of a nerve segment to the vein implant. Possible reasons for the positive effects of isolated nerve segment in bridging nerve gaps are discussed.

Animals↗
PubMed1993

Insect tolerance of transgenic Populus nigra plants transformed with Bacillus thuringiensis toxin gene.

Leaves and stem segments of Populus nigra were transformed with A. tumefaciens LBA4404 harboring a binary vector containing chimeric genes of NPT and 35S-omega-B.t. toxin-Nos. Nineteen regenerated kanamycin resistant plants were analyzed by DNA hybridization, out of which 10 were shown to be the candidates of transgenic plants. Insect tolerance tests showed that the transgenic plants were toxic to two lepidopteran pests, Lymantria dispar L. and Apocheimia cinerarius Erschoff. Based on the results of Southern blot of PCR products and the cluster analysis of their growth and insect resistance, three independent transgenic plants were selected, which were then propagated in the nursery field. This field test is currently in progress.

Agrobacterium tumefaciens↗
PubMed1992

Expression of sarcomeric myosin in the presumptive myocardium of chicken embryos occurs within six hours of myocyte commitment.

The distribution of sarcomeric myosin heavy chain (MyHC) has been examined immunocytochemically in the presumptive myocardial cells of chicken embryos (stages 6-10) prior to the onset of the heart beat. Embryos were stained with monoclonal antibody MF20, a reagent which recognizes all chicken sarcomeric MyHCs (Bader et al., 1982), and then examined both in whole mount by immunofluorescence and in semithin, plastic-embedded sections following immunoperoxidase labeling. We observed that myosin could be detected as early as stage 7 (0-2 pairs of somites) in 29% of the 31 embryos examined, and by stage 8 (4 pairs of somites) more than 80% of the embryos were MF20+. Every embryo with 5 pairs of somites (stage 8+) labeled strongly with MF20. Labeling was first detected at stage 7 to 7+ as a diffuse fluorescent signal within pleomorphic cells of the splanchnic mesoderm located in two crescent-shaped regions bordering each side of the anterior intestinal portal (AIP). With progressive development, the two crescent-shaped regions merged at the apex of the AIP, and as the two heart tubes began fusion at stage 9, the MyHC+ regions extended cranially and medially. By somite stages 9-10, the myosin-positive cells completely encircled the heart tube. From stages 7 to 9 the myosin signal had no sarcomeric distribution; i.e., there were no MyHC striations nor periodic repeats evident in the presumptive myocytes until late stage 9 and stage 10. Semithin sections revealed that myosin was first distributed in apical regions of the myocytes, adjacent to the pericardial coelom. The implications of these findings for myocyte determination, differentiation and morphogenesis are discussed.

Animals↗
PubMed1992

Dynamic response of coronary regulation to heart rate and perfusion changes in dogs.

The rate of change of coronary adjustment in the anesthetized dog to a step change in heart rate (HR) and in perfusion was analyzed. The left main coronary artery was perfused either at constant pressure (CP) or at constant flow (CF). Coronary arterial pressure and flow were continuously measured and averaged per beat, after which their ratio, being an index of coronary resistance in steady state, was calculated. The rate of change of pressure-to-flow ratio was quantified by t50, the time required to establish half of the completed response. The t50 values for the dilating responses at CP were 5.5 +/- 0.4 (SE) s for an increase in HR and 5.5 +/- 0.1 s for a decrease in perfusion. At CF these values were 9.3 +/- 0.9 and 9.7 +/- 1.6 s, respectively. The t50 values for the constricting responses with CP were 6.6 +/- 0.5 s for a decrease in HR and 6.2 +/- 0.2 s for an increase in perfusion. At CF these values were 12.2 +/- 1.5 and 10.8 +/- 2.2 s. The responses in the dog are faster than in the goat. Furthermore, the directional sensitivity in responses with perfusion changes, observed earlier in goats, is normally absent in dogs.

Animals↗
PubMed1992

Retrograde coronary flow is limited by time-varying elastance.

The study examined the influence of left ventricular pressure (PLV) on coronary arterial flow and pressure. In eight anesthetized open-thorax goats with cannulated and artificially perfused left main coronary artery, the PLV was disturbed by aortic occlusions. In the constant pressure perfusion (CPP) protocol the response of systolic arterial inflow on a change in PLV was studied with fixed perfusion pressure and at several perfusion pressure levels. Similarly, in the constant flow perfusion (CFP) protocol the response of systolic perfusion pressure was examined with fixed levels of perfusion flow and repeated for several flow levels. The results show an early systolic response determined by PLV for both protocols. Midsystolic responses were almost absent in the CPP protocol but present in the CFP protocol. At CPP, the effect of a change of PLV on arterial flow in mid systole was only 20% of that on early systolic flow with intact coronary tone and 33% with adenosine-induced vasodilation. At CFP the pulsations in perfusion pressure were 30% of PLV pulsations, both with intact tone and vasodilation; in contrast with the CPP results, no difference for this value was found in different stages of systole. We suggest that stiffness of cardiac muscle determines the influence of PLV on coronary flow. The difference in mid systolic relations between the CPP and CFP protocols is explained by the difference in time constants induced by the perfusion system. The results are best explained by a synthesis between the intramyocardial pump model and the elastance concept.

Animals↗
PubMed1992

Amino acid fortification of a low-protein corn and soybean meal diet for chicks.

Seven experiments were conducted to investigate whether a 19% CP corn and soybean meal (CS) diet could be fortified properly with amino acids (AA) to produce performance in 1- to 3-wk-old chicks equal to that obtained with a 23% CP, CS diet supplemented with Met. In one experiment, the assay was carried out to 6 wk of age. During 4- to 6-wk posthatching, the positive control was a 20% CP, CS diet with added Met and the low-protein diet was a 16% CP, CS diet fortified with limiting AA. The two most limiting AA in the low-protein diet (19% CP) were found to be Met and Lys. Arginine, Val, and Thr were observed to be limiting as well. Weight gain and feed efficiency were substantially increased and body fat content decreased when the low-protein diet was supplemented with the five limiting AA and amino nitrogen in the form of Glu. Addition of potassium had no effect on performance of chicks fed the AA-fortified, low-protein diet. With all trials considered together, chicks fed the low-protein diet fortified with the five limiting AA and Glu gained at the same rate with similar feed efficiency and had estimated body fat levels comparable to birds fed the 23% CP, positive control diet. From 3 to 6 wk of age, chicks fed the AA-fortified, 16% CP diet had growth performance similar to chicks fed the 20% CP, positive control diet.

Adipose Tissue↗
PubMed1992

[Electrophysiological observation on the role of the hypothalamic paraventricular nucleus in acupuncture analgesia].

In this experiment, the role of PVN in acupuncture analgesia was further investigated with electrophysiological technique. In wistar rats the unit discharge was recorded extracellularly, Noxious stimulation was applied to sciatic nerve, and the electroacupuncture was performed on acupoints "Zusanli" and "Sanyinjiao". Totally eighty-two units were recorded successfully from PVN. 49 units of them reacted to electroacupuncture with excitatory (14), inhibitory (23) or on significant effect (12). Various types of reactions including excitation (12), inhibition (6), excito-inhibition (4) or inhibito-excitation (3) were observed on 43 units during noxious stimulation of sciatic nerve. The remainder 18 units had no significant reaction. After electroacupuncture those units reacting with excitatory effect on noxious stimulation decreased their firing rate, and those with inhibitory effect increased their firing rate. The duration of nociceptive reaction was shortened after electroacupuncture in both types of units. It was suggested that electroacupuncture could influence the activities and decrease the nociceptive reactions of PVN neurons, which might be considered as electrophysiological evidence of the involvement of PVN in acupuncture analgesia.

Acupuncture Analgesia↗
PubMed1992

Protective effects of berberine and phentolamine on myocardial reoxygenation damage.

The protective effects of berberine and phentolamine against anoxia and reoxygenation damage in isolated rat hearts have been investigated. Incorporation of berberine (24.5 mumol/L) in both anoxic and aerobic perfusion media resulted in a significant reduction of CPK release during the reoxygenation period, and the ultrastructural damage was reduced as compared with the control group; the myocytes in the berberine-treated group displayed mild intracellular edema, well-registered myofibrils without contracted bands, and swollen mitochondria with partially broken cristae but without dense bodies. Berberine did not inhibit calcium and sodium accumulation or magnesium and potassium loss. Treatment with phentolamine (6.6 mumol/L), an alpha-adrenoceptor antagonist, had similar effects, though the CPK release profile was shifted to the right and downwards. These results suggest that although berberine and phentolamine have some beneficial effects on myocardial reoxygenation injury, they may not abolish the injury. Therefore alpha-adrenoceptor stimulation may not be the major mechanism behind the injury.

Adrenergic alpha-Antagonists↗
PubMed1992

[Studies of Rehmannia glutinosa Libosch. f. hueichingensis as a blood tonic].

We have studied the function of dried and prepared Rehmannia glutinosa f. hueichingensis in treating hemorrhagic anemic mice and in fostering bone marrow hematopoietic cells CFU-S, CFU-E. The results show that Rehmannia glutinosa f. hueichingensis can promote the recovery of blood deficient animals, RBC. Hb expedite the multiplication and differentiation of CFU-S, CFU-E, and thus proves markedly helpful to the generation of blood.

Anemia↗
PubMed1992

Assessment of cholinergic influences on a primary humoral immune response.

Cholinergic ligands can affect some lymphocyte functions, and binding of labelled cholinergic ligands to lymphocytes has been reported. However, the role of endogenous cholinergic stimulation in immunomodulation in vivo is unclear. It has been suggested that suppression of primary humoral immune responses in vivo by administration of organophosphorus compounds is caused by excessive cholinergic stimulation. If this is correct, it would demonstrate cholinergic immunomodulation in vivo and might serve as a useful model for the characterization of this phenomenon. In the present study, the organophosphorus insecticide parathion and its major metabolite, paraoxon, suppressed the primary IgM response to sheep red blood cells (SRBC) in vitro in Mishell-Dutton cultures at concentrations similar to those probably reached in vivo. In contrast, cholinergic agonists did not suppress the in vitro response, but tended to enhance it. However, antagonists also tended to enhance the response and the effects of agonists were not blocked by antagonists. Binding studies with a radiolabelled cholinergic antagonist ([3H-]QNB) did not indicate the presence of specific, saturable cholinergic receptors on lymphocytes. A membrane preparation from brain was used as a positive control, and specific, saturable binding was observed. These results suggest that suppression of primary immune responses in vivo by parathion is mediated at least in part by direct action of parathion and/or its major metabolite, paraoxon, on the immune system. The data provide no evidence that direct interaction of cholinergic ligands with the immune system contributes to parathion-induced immunosuppression. In fact, the absence of expected agonist-antagonist relationships in Mishell-Dutton cultures, the absence of saturable [3H]QNB binding, and puzzling inconsistencies in the literature on this subject cast doubt on the conclusion that lymphocytes express specific cholinergic receptors.

Acetylcholine↗
PubMed1991

Modulation of Na,K-ATPase expression during early development of Xenopus laevis.

In amphibian and mammalian systems, regulation of Na+ transport via the Na,K-ATPase plays an important role in distinct developmental processes such as blastocoele formation and neurulation. In this study, we have followed the Na,K-ATPase activity, the biosynthesis, and the cellular accumulation of catalytic alpha-subunits after fertilization of Xenopus laevis eggs up to neurula formation. Our data show that Na,K-ATPase activity increases significantly between stages 4 and 6 and again between stages 13 and 24. The four-fold rise in Na,K-ATPase activity during blastocoele formation is not mediated by an increased cellular pool of alpha-subunits. On the other hand, a five-fold increase of the biosynthesis rate around midblastula precedes a progressive accumulation up to neurula stage mainly of alpha 1-subunits and to a lesser extent of a second alpha-immunoreactive species. In contrast, newly synthesized glycoproteinic beta 1-subunits of Na,K-ATPase cannot be detected up to late neurula. These data indicate that (1) upregulation of Na,K-ATPase activity during blastocoele and neurula formation are mediated by different regulation mechanisms and (2) alpha- and possibly beta-isoforms are expressed in a developmentally regulated fashion during early Xenopus development.

Animals↗