Thermotolerance and heat shock response during early development of the mammalian embryo.
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Animals↗
Biomedical subjects
K Li
Publications and source records attributed to K Li.
Tyrosine hydroxylase and neuropeptide-Y immunoreactivity in pineal glands developing in situ and in pineal grafts.
Postnatal development of the innervation of the pineal gland in situ as well as the reinnervation of pineal grafts by tyrosine hydroxylase (TH)- and neuropeptide Y (NPY)-immunoreactive nerve fibers were examined using the avidin-biotin-peroxidase immunohistochemical technique. TH-immunoreactive nerve fibers appeared in the pineal gland on the second postnatal day (P2) in both hamsters and gerbils. NPY-immunoreactive nerve fibers first appeared in the pineal gland of gerbils on P2 and in the hamsters on P3. By the seventh postnatal day (P7), the pineal glands of both hamsters and gerbils were richly innervated by TH- and NPY-fibers that appeared as smooth fibers or fibers with sporadic varicosities. By the age of 4 weeks, the innervation of the pineal glands of hamsters and gerbils by TH- and NPY-fibers was fully developed. Abundant TH- and NPY-fibers formed a dense meshwork in the parenchyma of the superficial and deep pineals. The great majority of the fibers bore a large number of varicosities. More NPY-fibers were found in the pineal glands of gerbils than hamsters. NPY fibers were distributed evenly throughout the pineal glands of the gerbil, but they were more often located in the central region of the superficial pineal of the hamster. For the pineal grafts, superficial pineals from neonatal and 4-week-old hamsters were transplanted to different sites in the third cerebral ventricle (infundibular recess, posterior third ventricle) or beneath the renal capsule. The pineal grafts from 4-week-old donors appeared to undergo severe degeneration and eventually disappeared. The pineal grafts from neonatal hamsters, however, successfully survived and became well integrated into their new locations. Abundant TH- and NPY-fibers in the host brain were found surrounding the pineal grafts placed in the third cerebral ventricle, but were only rarely seen entering the parenchyma of the grafts. A few TH-fibers were demonstrated in the renal grafts 4 weeks after transplantation. These studies describe the postnatal development of the innervation of the pineal glands in situ by TH- and NPY-nerve fibers, and demonstrate a lack of reinnervation of cerebroventricular pineal grafts by TH and NPY fibers from adjacent host brain.
Animals↗
A comparison of absorbable suture and argon laser welding for lateral repair of arteries.
Conventional vascular anastomoses between autogenous vessels are performed with nonabsorbable sutures. Recently, use of absorbable sutures and laser-assisted vascular anastomoses has been advocated because of their improved healing characteristics. This study compared arterial repairs with the argon laser, absorbable suture, and nonabsorbable suture for technical characteristics including additional suture and overall success rates, burst strength, and cost. Absorbable and nonabsorbable suture closures were comparable with respect to technique, but laser-assisted vascular anastomosis was technically more demanding and required almost twice as much time for completion. The argon laser successfully closed only 58.6% of the arteriotomies, and 90% of the closures required additional sutures for complete hemostasis. All sutured arteriotomies were successfully completed by use of either absorbable or nonabsorbable suture. Burst strength was similar for all groups, but was uniformly greater than 300 mm Hg for sutured repairs, whereas two of five laser-assisted closures burst below 300 mm Hg. Finally, costs for purchasing ($35,000) and operating ($300/hr.) an argon laser make laser-assisted vascular anastomosis much more expensive than sutured repair. These data suggest argon laser-assisted vascular anastomoses are more technically demanding, less successful, and more expensive than conventional sutured anastomoses when evaluated in large caliber arteries in a canine model. Absorbable suture, however, is comparable to conventional nonabsorbable sutured arterial repairs in expense, handling characteristics, and success rates with the added advantage of eliminating permanent foreign body in the arterial wall when it is absorbed.
Absorption↗
Alpha 1-adrenergic stimulation increases the Vmax of isolated myocardial papillary muscles.
alpha-Adrenergic agonists have been shown to increase the tension developed by myocardial muscle. However, their effects on the maximum velocity of unloaded muscle shortening (Vmax) have not been rigorously examined. In this study, the contractile effects of the alpha-adrenergic agonist phenylephrine were examined in the presence of propranolol in papillary muscles of two species, the dog and the rabbit. In rabbit papillary muscles studied at physiological calcium concentrations (1.25 mM), phenylephrine increased all indices of contractility (Vmax, tension, and maximum rate of tension developed (dT/dt)) starting at 10(-8) M. The percent increase in Vmax (121 +/- 8%) was less than that of tension (188 +/- 20%, p less than 0.05) and dT/dt (262 +/- 35%, p less than 0.01). These findings occurred at both 29 and 35 degrees C and were inhibited by adding 10(-5) M prazosin. Increasing extracellular calcium concentration from 1.25 to 15 mM caused changes in twitch configuration that were significantly different from those of phenylephrine. Calcium increased all indices of contractility more than did phenylephrine. This was particularly true for dT/dt (502 +/- 82 vs. 262 +/- 35% for phenylephrine, p less than 0.01). Nonetheless, the ratio of increase in tension to increase in Vmax under both experimental conditions was similar (the increase in Vmax was 64% of that of tension with phenylephrine and 69% with increased calcium). At 1.25 mM calcium, the increase in contractility caused by phenylephrine was much smaller in dog myocardium as compared with rabbit myocardium. Rather, the effects of phenylephrine on dog myocardium studied at 1.25 mM calcium resembled that of rabbit myocardium studied at 15 mM calcium.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Myocardial contractile actions of endothelin-1 in rat and rabbit papillary muscles. Role of endocardial endothelium.
The actions of endothelin on the contractile and twitch configuration characteristics of rat and rabbit papillary muscles were evaluated before and after endocardial endothelium removal. In rabbit papillary muscles, endothelin produced a dose-dependent (10(-11) to 10(-7) M) increase in tension (T) (from 2.7 +/- 0.2 to 8.9 +/- 0.7 g/mm2, p less than 0.01), dT/dt, and Vmax (from 1.14 +/- 0.03 to 3.0 +/- 0.13 Lmax/sec, p less than 0.01), a decrease in time to peak tension (from 251 +/- 9 to 216 +/- 7 msec, p less than 0.05), and an increase in time to half relaxation (from 168 +/- 9 to 293 +/- 14 msec, p less than 0.01). Increasing calcium concentration in the bath from 1.25 to 15 mM greatly attenuated these changes. In the presence of propranolol (10(-5) M), endothelin increased all indexes of contractility but to a lesser extent (T = 2.6 +/- 0.3 to 6.5 +/- 0.2 g/mm2, p less than 0.01; Vmax = 1.16 +/- 0.10 to 2.06 +/- 0.10 Lmax/sec, p less than 0.01). Myocardial catecholamine depletion with reserpine had effects similar to those of propranolol. The myocardial contractile and twitch configuration characteristics of endothelin were similar to those of phenylephrine (10(-4) M), a strong stimulator of the phosphatidylinositol pathway and a moderate beta-adrenergic stimulator. The effects of phenylephrine and endothelin were modified in a similar manner by propranolol (10(-5) M). The presence of nicardipine (3 X 10(-7) M) decreased the absolute increase in contractility caused by endothelin but did not alter the percent change or shift the dose-response curve of endothelin. The actions of endothelin in rat papillary muscles studied at physiological calcium concentrations (Ca2+ = 1.25 mM) were less marked than those of rabbit studied at physiological calcium (Ca2+ = 1.25 mM) but similar to those of rabbit studied at high calcium concentrations (Ca2+ = 15 mM). Removing the endocardial endothelial layer of rabbit papillary muscles did not alter the absolute changes in contractility caused by endothelin but shifted the dose-response curve to the left and markedly altered the effects of endothelin on twitch configuration characteristics. Thus, it would appear that endothelin increases contractility and modifies twitch configuration. It does so more at lower rather than higher extracellular calcium concentrations and in a species, such as rabbit, that responds more to interventions that increase intracellular calcium.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Dysfunction of the beta- and alpha-adrenergic systems in a model of congestive heart failure. The pacing-overdrive dog.
The functional integrity of the beta- and alpha-adrenergic stimulatory pathways in a rapid ventricular pacing model of congestive heart failure in dogs was investigated; normal dogs served as controls. Total beta-adrenergic receptor density was 35% lower (p less than 0.01) in the pacing-overdrive dogs, and the beta-adrenergic receptor-mediated stimulation of adenylate cyclase (Vmax) was found to be 68% and 72% lower (p less than 0.01) in the left and right ventricles of the paced dogs. In addition, the basal adenylate cyclase activity was found to be 56% and 68% lower (p less than 0.01) in the left and right ventricles of the failing heart. Similarly, the Vmax of 5'-guanylylimidodiphosphate (GppNHp) and forskolin stimulation of adenylate cyclase activity was significantly lower, 70% and 55%, respectively (p less than 0.01), in both ventricles of the paced dogs. However, although the concentration yielding half-maximal velocity for beta-agonist and GppNHp stimulation of adenylate cyclase was similar in both groups, that for forskolin stimulation of the enzyme was significantly increased (p less than 0.01). Pertussis toxin-mediated ADP-ribosylation of membranes from control and failing hearts revealed a significant decrease in the inhibitory guanine nucleotide binding protein content (48 +/- 9%, p less than 0.01) in the hearts of the paced dogs. Moreover, although the pertussis toxin treatment increased the basal and the forskolin-stimulated adenylate cyclase activity in both normal and failing heart membranes, the adenylate cyclase activity remained significantly depressed in the failing heart after pertussis toxin treatment (p less than 0.01). Consistent with the depressed adenylate cyclase activity, mechanical studies on isolated papillary muscles and trabeculae revealed a decrease in baseline total tension (from 7.0 +/- 0.7 to 3.8 +/- 0.4 g/mm2, p less than 0.01) and dT/dt (from 26 +/- 8 to 13 +/- 1 g/mm2/sec, p less than 0.01) in the pacing-overdrive model. Tension generation and dT/dt observed in the paced dogs in response to increasing concentrations of forskolin demonstrated a rightward shift in the dose-response curve and a decrease in maximal forskolin stimulation (p less than 0.01). Similarly, maximal tension and dT/dt in the presence of isoproterenol was significantly lower than in the normal dogs (p less than 0.01). The decrease in beta-adrenergic responsiveness was accompanied by a decrease and rightward shift in alpha 1-adrenergic responsiveness (increase in tension was 1.1 +/- 0.1 g/mm2 in paced dogs versus 2.1 +/- 0.1 g/mm2 in controls, p less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)
Adenylyl Cyclases↗
Histopathological and ultrastructural changes of lichen sclerosus et atrophicus on the vulva.
Studies of 82 skin specimens from 81 cases of lichen sclerosus et atrophicus (LSA) are reported. Typical LSA pathological changes showed atrophy of the epidermis, hydropic degeneration at the basal layer, and homogenization of the collagen fibers in the superficial dermis with inflammatory cell infiltration underneath. Ultrastructural changes showed intercellular spaces enlarged, particularly near basal cells. Some mitochondria were swollen and rough endoplasmic reticula were enlarged. Some basement membranes were thinner, collagen fibers of varying diameters were arranged in irregular shapes and the fine structures had become unclear and had sometimes even disappeared.
Adolescent↗
Pharmacological studies of meisoindigo: absorption and mechanism of action.
Meisoindigo, an indirubin derivative, is a new type of cancer chemotherapeutic agent. It exhibited higher activity against rodent tumors than indirubin itself. Experiments have shown the improved absorption of meisoindigo, compared to indirubin to be one of the major reasons for the enhancement of antitumor activity. Studies on the mechanism of meisoindigo action indicate that it strongly inhibits DNA biosynthesis in tumor cells. Strong inhibition of the drug on assembly of microtubule protein was also obtained. By means of FCM technique the effects of meisoindigo on mouse leukemia L1210 cell cycle were examined. Experimental results showed that under the action of meisoindigo the S phase cells accumulated and the traverse of the cells in G2 + M phase to G1 phase may also be blocked to some extent.
Animals↗
[The significance of internal electronic monitoring of fetal heart rate. Report of 144 cases].
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Apgar Score↗
OXBOX, a positive transcriptional element of the heart-skeletal muscle ADP/ATP translocator gene.
Three positive transcriptional control regions have been identified in the promoter of the human heart-skeletal muscle adenine nucleotide translocator gene (ANT1). By transfecting promoter-chloramphenicol acetyltransferase fusion constructs into C2C12 myogenic cells, each positive region was found to increase transcription 2-3-fold. The first region spans from -123 to -674 base pairs (bp), the second from -2.6 to -3.1 kilobases, and the third from -3.1 to -8.8 kilobases. Linker-scanning mutants generated using the polymerase chain reaction and modified oligonucleotides have identified the OXBOX (5'-GGCTCTAAAGAGG) as the positive element within the -123 to -674-bp region. This element enhances transcription in muscle cells but not in HeLa cells, suggesting that it is muscle-specific. Gel retardation experiments have revealed a factor from C2C12 cells which specifically binds to a 40-bp piece of the ANT1 promoter containing the OXBOX. Since the OXBOX is also found in the promoter of the human ATP synthase beta subunit gene, it is the first tissue-specific element identified which could coordinately regulate mitochondrial oxidative phosphorylation genes.
Animals↗
Simple and rapid thin-layer chromatographic method for quantitative measurement of free cholesterol in serum.
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Adult↗
Benextramine: a long-lasting neuropeptide Y receptor antagonist.
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Adrenergic alpha-Antagonists↗
Determination of lipoperoxide in animal tissue by ion-pair reversed phase high performance liquid chromatography.
An ion-pair reversed phase high performance liquid chromatographic method was developed for the quantitative determination of lipoperoxide (as malondialdehyde, MDA) in animal tissue using a ODS column and a mobile phase of methanol + phosphate buffer (53:47 v/v, pH 6.5). Tetrabutylammonium bromide was used as an ion-pair reagent and the detection wavelength was set at 532 nm. The method was sensitive, accurate and simple. A linear relationship was obtained between the peak height and the amount of MDA from 50 nmol/L to 1200 nmol/L and the lower limit of detection of MDA was 15 nmol/L (signal-to-noise ratio greater than 2), and the coefficient of variation at the 200 nmol/L level was 3.7% (n = 7). The results correlated well with those from the 2-thiobarbituric acid colorimetric method. The method has been used in the pathogenic studies of cerebral ischemia and acute renal failure for the determination of trace lipoperoxide.
Acute Kidney Injury↗
Effects of pulsed ultrasound and temperature on the development of rat embryos in culture.
Rat embryos in culture were exposed to pulsed ultrasound at SPTA intensity of 1.2 W/cm2 for 5, 15, and 30 min on day 9.5 of development. The whole embryo culture system allowed precise temperature control for directly examining the effects of ultrasound on the developing neural plate. After exposure, embryos were maintained in culture for a further 48 hr. No major morphological abnormalities were observed but a reduction in somite number occurred in the group insonated for 30 min, which was equivalent to a 2 hr delay in embryonic development. Similar delay in growth and "blistering" in the prosencephalon region of some embryos were observed after insonation for 15 min at 40.0 degrees C, an elevation of 1.5 degrees C over the temperature used for controls. Exposure to ultrasound for 15 min at 40 degrees C caused significant reduction in the growth of the head compared with that of control embryos. Heat shock genes for hsps 71/73 and 88 kD were induced after insonation for 30 min at 38.5 degrees C. Insonation did not cause any temperature changes in the culture medium. However, when the temperature of the culture medium was increased during insonation, defective development occurred. The results of these in vitro experiments suggest that ultrasound if resulting in significant hyperthermia could affect the development during early organogenesis of the neural plate and in particular they suggest that the embryo is at greater risk of damage during hyperthermic conditions. These results should provoke discussion of the concept that ultrasound in the febrile patient may present an increased embryonic risk which should be considered when deliberating on the use of diagnostic ultrasound procedures in the pregnant patient.
Animals↗
A survey of cigarette smoking among middle school students in 1988.
A survey of the prevalence of smoking in middle school students aged 13-21 years in Harbin city, China, was undertaken in the Spring of 1988. A random sample of 4712 students was selected using proportional stratified clustering. A self-administered confidential questionnaire relating to smoking habits and certain family and school factors was administered. The results showed that 1.29% of the students (2.21% boys and 0.38% girls) smoked regularly, 5.62% (10.52% boys and 0.76% girls) were light smokers and 13.77% (24.29% boys and 2.92% girls) smoked only occasionally. Smoking habits were related to the type of school and to age, there being a higher proportion of smoking in senior grade students. Students were significantly more likely to smoke if they were male and if their siblings smoked. Prevalence of regular smoking was not related to parental occupation or family income. It is suggested that anti-smoking education in the school curriculum should be directed towards students in middle school.
Adolescent↗
Characterization of gentamicin-resistant respiratory-deficient (res-) variant strains of Staphylococcus aureus.
Exposure of sensitive cells of Staphylococcus aureus to concentrations of gentamicin higher than the minimal inhibitory concentration, results in the recovery of low level resistant strains with a greatly altered phenotype (variants). Because the phenotypic alteration in these strains is so great the expected diagnostic characterization of these variants as S. aureus is obscured. Starting with a genetically-marked parent strain, a comprehensive cytological, physiological, morphological, genetic and biochemical analysis of the variants isolated from it was carried out. The genetic lineage of the variants to the parent was also established by DNA/DNA hybridization. Variants result from mutations in the hemin biosynthesis locus, the effect of which is to disrupt the synthesis of components of the electron transport system, lipid synthesis and selected nucleotide synthesis. Thus the strains are defective in aerobic and anaerobic respiration, (res-), in active transport of aminoglycosides (which confers low level resistance), export of characteristic exo-enzymes, and in cell wall composition and structure.
Bacteriophages↗
Some effects of tripotassium dicitrato bismuthate on gastric secretion and the mucus barrier.
The effect of tripotassium dicitrato bismuthate (De-Nol) on the breakdown of the gastric mucus barrier was investigated by measuring the output of mucus glycoprotein in pentagastrin-stimulated secretion from 13 patients before and after treatment for peptic ulcer, and by examining the accumulation of dialysable peptides and amino acids (DPAA) in stimulated secretion from ten of these patients. The accumulation of DPAA was significantly reduced after De-Nol (by 54%) and to a greater extent than was the output of mucus glycoprotein (by 27%). These observations are consistent with a decrease in the rate of breakdown of the mucus barrier as a result of De-Nol treatment. De-Nol significantly reduced pepsin output (by 32%) in the same group of patients. Comparison of the change in pepsin output with the change in accumulation of DPAA in stimulated juice indicated that De-Nol increases the resistance of the mucus barrier to acid-pepsin proteolysis and/or inhibits the secretion of amino acids and peptides from gastric mucosa.
Adult↗
[The role of hemorheologic changes in the pathogenesis of acute hemorrhagic necrotizing pancreatitis].
The hemorheologic alterations were studied in experimental acute hemorrhagic necrotizing pancreatitis (AHNP) which was induced by injection of 5% sodium taurocholate into the main pancreatic duct. The results showed that during the early stage of AHNP, all of hemorheologic parameters were significantly elevated, and continually increased at the rest intervals. The authors suggested that the blood viscosity and hematocrit increase, red blood cells tend to aggregate, and erythrocyte deformation decrease are the causation of pancreatic microcirculatory disturbances and promoting pancreatic progressive necrosis. After using low molecular dextran and Salvia miltiorrhizae, the hemorheologic alterations in AHNP were recovered, and the histologic observation improved. Our data indicate the hemorheologic disturbances is one of the key factors in the pathogenesis of AHNP.
Acute Disease↗