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Biomedical subjects

Y Han

Publications and source records attributed to Y Han.

At least 19 recordsLinked to original sources
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↗
PubMed1991

Nutritional evaluation of soybeans varying in trypsin inhibitor content.

A series of experiments was conducted to assess, by various methods, the nutritional value of a raw, Kunitz inhibitor-free, low trypsin-inhibitor soybean variant (LTS) in comparison with raw conventional soybeans (RCS) and heated dehulled soybean meal (HDS). The gross energy, protein, and amino acid concentrations of LTS were similar to those of RCS. The protein quality of the soybeans was compared in two trials in which young chicks were fed 9% or 16% CP diets containing one of the soybeans as the sole source of dietary protein. The protein quality of LTS was superior to that of RCS but inferior to that of HDS. True digestibilities of amino acids and TMEn were determined with a precision-fed cockerel assay using conventional and cecectomized birds. No significant effect of bird type on digestibility was found. The mean digestibility of 16 amino acids in RCS, LTS, and HDS was found to be approximately 68, 83, and 92%, respectively. The TMEn of LTS was greater than that of RCS. Chick growth assays indicated that amino acid bioavailability values of lysine and TSAA for LTS were greater than those for RCS but slightly lower than those for HDS. In an additional chick assay with a corn and HDS diet (22% CP), the dietary HDS protein was replaced with LTS or RCS protein at 25, 50, 75, or 100%. Performance of chicks fed LTS was better than that of chicks fed RCS at all replacement levels, but the difference was not significant at the 25% replacement level. Feed efficiencies of chicks fed 25 or 50% of the dietary soybean protein as LTS were not significantly different from that of chicks fed the corn and HDS control diet. The results of the present study indicated that the nutritive value of LTS is substantially greater than that of RCS but somewhat lower than that of HDS.

Amino Acids↗
PubMed1991

Research note: effect of excess lysine, methionine, threonine, or tryptophan on production performance of laying hens.

An experiment was conducted with laying hens to determine effects of feeding excesses of several individual amino acids in a practical layer diet. Single Comb White Leghorn hens, which were in peak production (31 wk of age), were assigned to one of five dietary treatments: a 16% CP corn and soybean meal positive control diet, or this diet fortified with 1% additional L-Lys, 1% additional DL-Met, 1% additional L-Thr, or 1% additional L-Trp. The diets were fed for ad libitum intake for 4 consecutive wk of production. For the entire production period, hen-day egg production, egg yield, and feed intake were not significantly different among any of the treatments. The study indicated that considerable tolerance exists in high-producing laying hens for individual excesses of the amino acids commonly used as supplements in poultry diets.

Analysis of Variance↗
PubMed1991

Subungual exostosis.

From 1980 through 1990, twenty-two patients with subungual exostosis were treated in PUMC Hospital and the Sixth Hospital of Beijing. The incidence of subungual exostosis was 4.6% among all bone tumors. Post-adolescents and young adults were most commonly affected, and the female to male ratio was 1.75 to 1. The great toe was the most often involved site. Radiological findings were found to be diagnostic, and local tumor excision is the treatment of choice.

Adolescent↗
PubMed1991

[Comparative study of the measured values of different periodontal probes].

A 0.25 N hinged constant force probe (Borodontic) and two inflexible probes (WHO, PCP-11) were used for probing. The mean probing depth differences between WHO and Borodontic as well as between Borodontic and PCP-11 were significant. Deepest probing levels were found with WHO and shallowest levels with Borodontic. Also, the pockets in patients with higher sulcus bleeding index presented shallower probing levels with Borodontic than the other probes.

Adult↗
PubMed1991

Characteristics of HIV-infected adults in acute care hospitals in New York State, 1984-1986.

The New York State acute care, hospital discharge database was used to create a longitudinal case history file for all adult inpatients infected with the human immunodeficiency virus (HIV). From 1984 through 1986, 12,958 individuals with HIV-related diseases were treated in acute care hospitals throughout the state. Approximately 80% of those people resided in New York City, and nearly half of them were between ages 30 and 39 years. Over the three-year period, the proportion of females increased from 11.8% to 16.6%. The per diem charge increased slightly, although the total length of stay for the first year of HIV illness declined sufficiently to decrease the total charge for the year. Examination of the pattern of inpatient stays and intercurrent days shows the first and last hospital stays to be longer than those in between, although the days between stays decreased as the number of admissions increased. The hospital stay in which a patient died was typically of longer duration than earlier stays. The average charge for HIV-related hospital care among inpatients during their first year of illness was approximately $20,000.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Assessment of intestinal amino acid availability in cattle by use of the precision-fed cecectomized rooster assay.

The digestibilities of amino acids in duodenal digesta of steers were measured using a precision-fed cecectomized rooster assay. Freeze-dried duodenal digesta from steers fed five different diets were utilized. Amino acids present in digesta of steers fed diets supplemented with corn gluten meal were more digestible than those from digesta of steers fed diets supplemented with soybean meal, blood meal, fish meal, or no true protein source. Measurements of amino acid digestibility in the cecectomized rooster were similar to those obtained previously when measured with reference to chromic oxide in steers fitted with duodenal and ileal cannulae, suggesting that the precision-fed cecectomized rooster assay is an appropriate technique for estimating small intestinal digestibility of amino acids in cattle.

Amino Acids↗