Search PubMed⌕ Search

Biomedical subjects

D C Lee

Publications and source records attributed to D C Lee.

At least 163 records · Page 9Linked to original sources
PubMed1981

Effect of ether, ethanol and aqueous extracts of ginseng on cardiovascular function in dogs.

Ether, ethanol and aqueous extracts of ginseng were serially prepared from Korean ginseng plants. Each extract in the dose of 40 mg/kg was administered intravenously to ten dogs under light halothane anesthesia while 11 cardiovascular variables were compared during the ensuing two hours. The variable included cardiac output, stroke volume, heart rate, mean arterial pressure, pulse pressure, central venous pressure, total peripheral resistance, pH, PaCO2, PaO2 and base deficit. Following the administration of the ether extract (40 mg/kg) the heart rate and the central venous pressure decreased significantly. The administration of ethanol extract (40 mg/kg) caused a significant decrease in the heart rate and the mean arterial pressure. After the administration of the aqueous extract (40 mg/kg) the cardiac output, stroke volume and central venous pressure were significantly decreased, while the total peripheral resistance was significantly increased.

Animals↗
PubMed1980

Regulation of gene transcription by estrogen and progesterone. Lack of hormonal effects on transcription by Escherichia coli RNA polymerase.

Estrogen and progesterone markedly stimulate transcription of ovalbumin and conalbumin (transferrin) genes in chick oviduct as measured by hybridization of labeled RNA synthesized in isolated nuclei to immobilized plasmid DNA containing these gene sequences. Using this direct assay for specific gene transcription, we explored the basis of previous reports indicating that steroid hormones also cause changes in oviduct chromatin structure that can be detected by Escherichia coli RNA polymerase. We observed no effect of these hormones on the ability of E. coli RNA polymerase to transcribe specifically the conalbumin and ovalbumin genes 8 1/2 h after hormone administration when transcription of these genes by endogenous RNA polymerase was elevated 5- and 30-fold, respectively. Furthermore, we were unable to detect any significant effect of either of these hormones on the total number of E. coli RNA polymerase binding sites in oviduct nuclei or chromatin. In contrast, after several days of hormone administration, we detected an apparent preferential ovalbumin RNA synthesis by E. coli RNA polymerase and this effect could be transferred to unstimulated nuclei by a 0.35 M salt extract of active nuclei. However, further experiments revealed that this preferential ovalbumin RNA synthesis is an artifact produced by transcription from contaminating ovalbumin mRNA. We conclude that E. coli RNA polymerase does not recognize steroid hormone-induced changes in oviduct chromatin.

Amanitins↗
PubMed1980

The chicken transferrin gene. Restriction endonuclease analysis of gene sequences in liver and oviduct DNA.

The organization of the chicken transferrin gene and its surrounding sequences was determined by a comparison of the restriction map of the cloned structural gene (double-stranded cDNA) with the map of the transferrin gene in genomic DNA. This analysis reveals a complex arrangement of the transferrin gene in which structural sequences are interrupted by a minimum of 6 intervening sequences, and span at least 10 kilobases in genomic DNA. Furthermore, comparison of the DNA from individual chickens of the same breed indicates considerable allelic diversity in the restriction sites for Eco RI, HindIII, and Bam HI. Quantitation of the number of transferrin genes by saturation hybridization confirms that both liver and oviduct DNAs contain only 1 transferrin gene/haploid complement, and, in addition, comparison of the restriction patterns obtained with DNA from these two tissues, as well as erythrocyte DNA, does not reveal any difference in the structural organization of the gene. We conclude that the distinct tissue-specific transcriptional regulation of this gene by steroids and iron levels in the oviduct and liver cannot be explained either by a multiplicity of genes or by somatic reorganization of the gene.

Animals↗
PubMed1980

Transferrin gene expression. Effects of nutritional iron deficiency.

Nutritional iron deficiency was produced experimentally by raising newly hatched chicks on an iron-deficient diet for several weeks. During this time, hematocrit and hemoglobin values declined, iron stores were depleted, and the circulating level of transferrin increased 2- to 4-fold. The increase in serum transferrin was related to a similar increase in the rate of transferrin synthesis in liver. In addition, the level of transferrin mRNA sequences, as determined by hybridization to a specific cDNA, increased 2- to 3-fold, and more than 80% of the transferrin mRNA was associated with polyribosomes in both control and iron-deficient liver. These results demonstrate that the induction of transferrin synthesis in iron-deficient chicks is regulated directly by an increase in transferrin mRNA. The iron-mediated effects on transferrin also appear to be gene-specific since the rate of synthesis of serum albumin, the major secretory product of liver, was unaffected by any of the experimental conditions. Furthermore, when iron stores were rapidly replenished by the administration of iron-saturated ferritin, both the rate of transferrin synthesis and the level of transferrin mRNA returned to control values with 2 to 3 days.

Animals↗
PubMed1980

Comparison of sodium salicylate, morphine sulfate, and acupuncture at Jen-Chung (Go-26) on the cardiovascular system of dogs.

The cardiovascular effects of the administration of sodium salicylate (100 mg/kg), the administration of morphine sulfate (0.5 mg/kg) and acupuncture by electrocautery at Jen-Chung (Go-26) were compared in groups of dogs under 0.75% halothane anesthesia. Cardiac output (CO), stroke volume (SV), heart rate (HR), mean arterial pressure (MAP), pulse pressure (PP), central venous pressure (CVP), total peripheral resistance (TPR), pH, PaCO2, PaO2 and base deficit were measured over a two hour period. A significant increase in CO, SV, PP, and CVP in addition to a significant decrease in TPR were observed following the administration of sodium salicylate. Morphine sulfate decreased the CO, HR, and MAP significantly while the SV and PP were significantly increased. Acupuncture by electrocautery at Jen-Chung (Go-26) produced a significant increase in CO, SV, HR, MAP, and PP and a significant decrease in TPR. This model was satisfactory in comparing cardiovascular changes evoked by a mild analgesic, sodium salicylate, a potent opiate, morphine sulfate, and acupuncture by electrocautery at Jen-Chung (Go-26).

Acupuncture Therapy↗
PubMed1979

Cloning of an almost full-length chicken conalbumin double-stranded cDNA.

Chicken conalbumin double-stranded cDNA (con-dscDNA) was synthesized from a laying hen oviduct mRNA preparation enriched for conalbumin mRNA (con-mRNA). The dscDNA was inserted by blunt-end ligation into the Sal I site of plasmid pBR322 which had been repaired with DNA polymerase I to create Taq I sites on each side of the inserted fragment. After bacterial transformation, one hybrid recombinant, pBR322-con1, which contains the largest inserted dscDNA (about 2350 bp) was shown to hybridize specifically to the RNA which is translated into conalbumin. Electron microscopic examination of hybrid molecules between con-mRNA and pBR322-con1 DNA indicate that the inserted con-dscDNA is an almost full-length double-stranded transcript of conalbumin mRNA.

Animals↗
PubMed1979

Can naloxone inhibit the cardiovascular effect of acupuncture?

Forty dogs were studied during MAC-1 halothane anesthesia with a chronically implanted electromagnetic flow probe on the ascending aorta. Cardiac output, stroke volume, heart rate, mean arterial pressure, pulse pressure, central venous pressure and total peripheral resistance were determined in addition to Pao2, pH, Paco2 and base deficit. Acupuncture moxibustion with electrocautery at Jen Chung (Go-26) produced a significant (five per cent level) increase in the cardiac output, stroke volume, heart rate, mean arterial pressure and pulse pressure and a significant decrease in total peripheral resistance during a 120-minute period of observation in dogs under halothane anaesthesia. Acupuncture moxibustion at Go-26 following pretreatment with the narcotic antagonist naloxone (1 mg.kg-1) produced a significant increase in cardiac output, heart rate, mean arterial pressure. It is concluded that naloxone, which inhibits the analgesic effects of acupuncture, does not inhibit the symphathomimetic effect of acupuncture or moxibustion at Jen Chung (Go-26) in dogs under light MAC-1 halothane anaesthesia.

Acupuncture Therapy↗
PubMed1979

Effects of the second (ethanol) extract of ginseng on the cardiovascular dynamics of dogs during halothane anesthesia.

An electromagnetic flowmeter probe was chronically implanted around the ascending aorta in a group of dogs. Subsequently, ten dogs were lightly anesthetized with halothane (0.75%), and a second (ethanol) extract of ginseng (40 mg/kg) was administered intravenously. Five dogs were anesthetized without the administration of ginseng. Eleven cardiovascular variables including cardiac output, stroke volume, heart rate, mean arterial pressure, pulse pressure, central venous pressure, total peripheral resistance, pH, PaCO2, PaO2, and base deficit were compared for two hours. The heart rate and mean arterial pressure were significantly decreased following ginseng. There were no other meaningful changes in either group.

Anesthesia, Inhalation↗
PubMed1979

Effects of the third (aqueous) extract of ginseng on the cardiovascular dynamics of dogs during halothane anesthesia.

An electromagnetic flowmeter probe was chronically implanted around the ascending aorta in a group of dogs. Subsequently, ten dogs were lightly anesthetized with halothane (0.75%) and the third (aqueous) extract of ginseng (40 mg/kg) was administered intravenously. Five dogs were anesthetized without the administration of ginseng. Eleven cardiovascular variables including cardiac output, stroke volume, heart rate, mean arterial pressure, pulse pressure, central venous pressure, total peripheral resistance, pH, PaCO2, PaO2, and base deficit were compared. The cardiac output, stroke volume, and central venous pressure were decreased significantly, while total peripheral resistance was increased significantly following ginseng.

Anesthesia, Inhalation↗
PubMed1979

Can an extract of deer antlers alter cardiovascular dynamics?

Ten (10) dogs were maintained under 0.75% halothane anesthesia while 11 cardiovascular parameters were studied before and following intravenous administration of an extract prepared from deer antlers. The eleven variables including cardiac output, stroke volume, heart rate, mean arterial pressure, pulse pressure, central venous pressure, total peripheral resistance, pH, PaCO2, PaO2 and base line deficit were studied. Stroke volume was consistently elevated during the period of observation and significantly elevated at two time intervals. Other values were not altered significantly. Extract from deer antlers does not appear to have a great acute effect on the cardiovascular system of this animal model.

Animals↗
PubMed1979

Modification by propranolol of cardiovascular response to hypercapnia during halothane anaesthesia.

The purpose of this study is to determine the effect of propranolol on the cardiovascular response to carbon dioxide (0-20%) during anaesthesia with 1% halothane in oxygen (blood level 16.3 mg/100 ml S.D. +/- 5) in dogs each with a chronically implanted electromagnetic flow probe on the ascending aorta. Cardiac output, stroke volume; heart rate, mean arterial pressure (MAP) and total peripheral resistance (TPR) were obtained and paired with arterial blood gas determination after each step of increased concentration of carbon dioxide with or without propranolol. Propranolol (0.06-0.9 mg/kg) prevented the response to elevation of inspired carbon dioxide of increased heart rate, stroke volume, and cardiac output, TPR and MAP were reduced by CO2 and only slightly changed in the propranolol series.

Anesthesia↗
PubMed1978

Identical precursors for serum transferrin and egg white conalbumin.

The NH2-terminal sequences of egg white conalbumin and chicken serum transferrin were examined and found to be identical. Conalbumin, when synthesized in a rabbit reticulocyte cell-free translation system, was found to contain an NH2-terminal extension of 19 amino acid residues. Sequential Edman degradation of this precursor (pre-conalbumin) labeled with radioactive amino acids revealed the following sequence: formula see text: The vertical line indicates the site at which pre-conalbumin is cleaved to yield authentic conalbumin. The sequence represents the primary translation product since the NH2-terminal methionine was shown to be derived from initiator Met-tRNAfMet. A partial NH2-terminal sequence of transferrin synthesized in vitro was also determined (underlined residues) and it is identical with that of pre-conalbumin.

Amino Acid Sequence↗
PubMed1978

Effects of the first (ether) extract of ginseng on the cardiovascular dynamics of dogs during halothane anesthesia.

An electromagnetic flowmeter probe was chronically implanted around the ascending aorta in ten dogs. Subsequently, these animals were maintained under halothane (0.75%) anesthesia during the intravenous administration of an ether extract (40 mg/kg) of ginseng. Five other dogs were anesthetized without injecting ginseng. Eleven cardiovascular variables including cardiac output, stroke volume, heart rate, mean arterial pressure, pulse pressure, central venous pressure, total peripheral resistance, pH, PaCO2, PaO2 and base deficit were compared during the ensuing 120 minutes. The heart rate was significantly decreased and central venous pressure increased significantly following ginseng. There were no other meaningful changes in either group.

Anesthesia↗