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Biomedical subjects

M Sun

Publications and source records attributed to M Sun.

At least 37 records · Page 2Linked to original sources
PubMed1994

Cardiorespiratory behavior during sleep in full-term and preterm neonates at comparable postconceptional term ages.

Cardiorespiratory behavior during sleep has been investigated by comparing visually analyzed minutes of EEG sleep with the digitized values of these two physiologic variables for each corresponding minute. Continuous 3-h nighttime sleep studies on 37 full-term and preterm neonates at comparable postconceptional term ages were acquired under controlled conditions, using a 24-channel computerized monitoring system and an automated event-marker program. Five thousand, two hundred ninety-four minutes were assigned an EEG state by traditional criteria. Eighteen preterm infants were compared with 19 full-term infants with respect to six cardiac and six respiratory measures: two nonspectral calculations (i.e. average per minute and variance of the means) and four spectral calculations of the cardiorespiratory signal (i.e. bandwidth, spectral edge, mean frequency, and ratio of harmonics). The relative capabilities of these measures to predict a sleep state change were investigated using discriminant analysis. A stepwise selection algorithm in discriminant analysis was used to identify the order of significance for the remaining variables. Eight cardiorespiratory measures were then submitted to multivariate analysis of variance to assess sleep state or preterm-full-term differences: mean frequency, bandwidth, average per minute, and ratio of harmonics for cardiac signals; and spectral edge, mean frequency, logarithm of variance, and ratio of harmonics for respiratory signals. Differences among the sleep states and between neonatal groups were highly significant (p < 0.0001). Interaction between sleep state and neonatal group was also significant (p < 0.034). Two variables differentiated preterm from full-term respiratory behavior: ratio (p < or = 0.001) and mean frequency (p < or = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular Physiological Phenomena↗
PubMed1994

Screening anti-HIV Chinese materia medica with HIV and equine infectious anemic virus reverse transcriptase.

The inhibitory activities of human immunodeficiency virus reverse transcriptase (HIV-RT) inhibitors PFA and Suramin against HIV-RT and equine infectious anemic virus reverse transcriptase (EIAV-RT) were studied in this paper. The 50% inhibitory concentration (IC50) of HIV-RT and EIAV-RT treated by PFA and Suramin were 0.2 mumol, 9.8 mumol and 17 mumol, 19.9 mumol, respectively. More than thirty Chinese medicines, including recipes, herbs, extracts of traditional materia medica and isolated compounds were tested using HIV-RT and EIAV-RT as target enzymes. It was found that 5 crude extracts such as Rhizoma Polygoni Cuspidati, and Radix Notoginseng, 7 isolated compounds like Flavone of Ramulus Visci, Flavone of Ajuga Decumbens Thumb, and Aristolochic acid, as well as the extract of the complex prescription Xiao Chai Hu Tang have shown various inhibitory actions on these two enzymes. The activities of the two enzymes were comparable, but HIV-RT was more sensitive, suggesting that HIV-RT can be used as index for the screening of anti-aids drugs.

Animals↗
PubMed1993

Effect of immune RNA on NK activity of infants born to mothers with cytomegalovirus infection.

The effect of specific immune RNA (i-RNA) on the activity of natural killer (NK) cells in the peripheral blood of 27 newborn infants was studied by lactic dehydrogenase (LDH) release assay. Peripheral blood mononuclear cells (PBMC) were used as effector cells with K-562 tumour cells as target cells. The results showed that in the therapeutic group (n = 17) the average activity of NK cells after therapy (24.13 +/- 4.62%) was 13.67 +/- 5.79% higher than before therapy (10.47 +/- 3.57%). In the control group (n = 10) these were only 10.78 +/- 3.94% and 11.58 +/- 3.37%, the difference was not statistically significant (P > 0.05). However, NK activity in the therapeutic group and control group was markedly different (P < 0.01). The data indicate that specific i-RNA can enhance the activity of NK cells in the peripheral blood of newborn infants. Therefore, we believe that specific i-RNA may play an important role in defence against CMV infection. The mechanism of i-RNA augmenting NK cellular activity is also discussed.

Cytomegalovirus↗
PubMed1992

Peptidolytic monoclonal antibody elicited by a neuropeptide.

We report evidence that a monoclonal antibody raised by immunization with a vasoactive intestinal peptide (VIP)-carrier protein conjugate selectively hydrolyzes VIP and a fluorescence quenched decapeptide (FQ14-22D), representing the region of VIP most susceptible to autoantibody-mediated cleavage (residues 14-22). A high affinity of the antibody for VIP and a lower affinity for FQ14-22D were revealed by kinetic studies and further substantiated by potent inhibition of FQ14-22D cleaving activity by full-length VIP. Sequencing of FQ14-22D hydrolysis products indicated selective cleavage at one peptide bond. These observations suggest that antibodies induced against naturally occurring polypeptide antigens can express peptidolytic activity targeted for specific sequences in the recognition epitope.

Amino Acid Sequence↗
PubMed1992

Chemical investigation of the metabolites from the Canadian tuckahoe, Polyporus tuberaster.

The metabolites of the Canadian tuckahoe, the sclerotium of Polyporus tuberaster, have been investigated. The ten-membered lactone tuckolide [1] was isolated, and its structure was determined by spectroscopic methods and confirmed by X-ray crystallography. Ergosterol, ergosterol peroxide, and several unidentified ergosterol derivatives were also obtained, along with an unidentified disaccharide.

Animals↗
PubMed1992

Nutrient balance and energy expenditure during ad libitum feeding of high-fat and high-carbohydrate diets in humans.

To study the influence of diet composition on regulation of body weight, we fed 21 weight-stable subjects (11 lean, 10 obese) high-carbohydrate (HC) and high-fat (HF) diets for 1 wk each. Although diet composition was fixed, total energy intake was unrestricted. Subjects had a higher energy intake on the HF (11,039 +/- 2700 kJ/d) than on the HC (10,672 +/- 2617 kJ/d) diet (P less than 0.05), but energy expenditure was not different between diets. On day 7 of the HC diet, carbohydrate (CHO) oxidation was significantly related to CHO intake with the slope of the regression line 0.99, suggesting that overall CHO balance was near zero. However, the slope of the regression line was greater for obese than for lean subjects. On day 7 of the HF diet, fat oxidation was significantly related to fat intake but the slope of the line was 0.50, suggesting that overall fat balance was positive. However, this relationship was due entirely to lean subjects, with obese subjects showing no relationship between fat intake and oxidation.

Adult↗
PubMed1992

Short-term effects of dietary-fat ingestion on energy expenditure and nutrient balance.

Joule for joule, dietary fat may promote obesity more than protein or carbohydrate. In this study we determined whether the addition of 50 g dietary fat to a standard breakfast would increase energy expenditure or fat oxidation during the immediate 6-h postprandial period or over the ensuing 18 h. We also determined whether subjects with a high level of aerobic physical fitness would show a greater increase in fat oxidation after the ingestion of the extra fat than would less fit subjects. Adding fat did not increase fat oxidation or energy expenditure either during the immediate 6-h postprandial period or over the following 18 h. This was true regardless of the subject's fitness level. Acutely, dietary fat ingested in excess of its usual rate of oxidation appears to be stored in the body. Being physically fit does not appear to provide an advantage in avoiding short-term storage of excess dietary fat.

Adult↗
PubMed1992

Relationship between aerobic fitness level and daily energy expenditure in weight-stable humans.

The relationship between exercise and energy expenditure is unclear, with some suggestions that exercise leads to increased energy expenditure over and beyond the increase due to the exercise itself. In this cross-sectional study, we examined the relationships among aerobic fitness level, body composition, and total daily energy expenditure in 78 subjects. Daily energy expenditure (determined in a whole room calorimeter) was significantly correlated with both fat-free mass (FFM) and aerobic fitness (estimated from maximum aerobic capacity or VO2max). However, multiple-regression analysis demonstrated that, after accounting for FFM, VO2max did not explain a significant amount of the remaining variation in energy expenditure. In addition, the relationship between resting metabolic rate and both FFM and VO2max was evaluated using data from 214 weight-stable subjects analyzed retrospectively. The results were identical with the results obtained from the 78 subjects in that VO2max did not have effects independent of FFM on energy expenditure. We conclude that aerobic fitness does not have a direct effect on energy expenditure. However, it may have effects that are mediated through body composition, since in both populations studied here, VO2max was positively correlated with FFM and negatively correlated with adiposity.

Aerobiosis↗
PubMed1992

[Effects of ANF and ACTH on aldosterone secretion in cultured human adrenal tissue].

We studied the effects of various concentrations of ANF and ACTH on aldosterone secretion in human normal adrenal tissue over different response times in vitro. We found that ANF 10(-8) mol/L at first stimulated but 24 h later inhibited basal aldosterone secretion. ANF 10(-8) mol/L also inhibited the ACTH-stimulated secretion of aldosterone. ACTH 10(-8) mol/L did not stimulate aldosterone secretion, while ACTH concentrations of 3 x 10(-8) and 5 x 10(-8) mol/L did. When ACTH and ANF were added simultaneously, the ANF-induced inhibition of ACTH-stimulated aldosterone secretion could be overcome by increasing the concentration of ACTH. Our results show that ANF caused a dose-dependent and time-dependent inhibition of basal and ACTH-stimulated increases in aldosterone secretion.

Adrenal Glands↗
PubMed1991

Effect of prior immunity on the shedding of virulent revertant virus in feces after oral immunization with live attenuated poliovirus vaccines.

Groups of infants were immunized with one or two doses of orally inoculated live attenuated Sabin poliovirus vaccine (OPV group) or with one or two doses of enhanced-potency inactivated poliovirus vaccine (EIPV) administered parenterally followed by one or two doses of OPV (EIPV-OPV group). The fecal specimens from both groups were tested for poliovirus shedding 1-2 months after OPV. The virus isolates were examined for nucleic acid sequences in the 5' noncoding regions (bases 480, 481, and 472 for serotypes 1, 2, and 3, respectively) to determine whether the viruses shed represented nonattenuated revertants, attenuated parent vaccine strains (nonrevertants), or both. In the OPV group, 4 of the 6 virus isolates recovered 30-60 days after the first immunization dose and 1 of the 3 isolates obtained after the second dose were found to be nonrevertants (parent vaccine strain). In contrast, 11 of the 12 isolates in the EIPV-OPV group were of the nonvaccine revertant virus types. The frequency for reversion appeared to differ for different poliovirus serotypes. However, all revertant type 3 isolates were recovered from subjects previously immunized with EIPV.

Antibodies, Viral↗
PubMed1991

[Effects of noxious stimuli on the discharges of pain-excitation neurons and pain-inhibition neurons in the nucleus ventralis posterolalis of thalamus in the rat and a modulating action of electroacupuncture on its electric activities].

The somatic and visceral noxious stimuli could simultaneously induce the increase of discharges of pain-excitation neurons (PEN) and the decrease of discharges of pain-inhibition neurons (PIN) in the Nucleus Ventralis posterolalis (VPL) of thalamus in the rat, and the electric activities of the two kinds of neurons cooperated each other. By the injection of morphine (5 mg/kg) and the electroacupuncture of "zusanli", the discharges of PEN were reduced and the discharges of PIN were enhanced. The results suggested that VPL of thalamus in the rat be involved in the modulating action on pain sensation and the analgesic effects of morphine and electroacupuncture by the simultaneous electric activities of PEN and PIN in VPL.

Animals↗
PubMed1990

Computer analyses of EEG-sleep in the neonate: methodological considerations.

Neonatal EEG interpretation can aid in the estimation of central nervous system maturation, as well as provide diagnostic and prognostic information of the high-risk infant. However, one cannot easily visualize the complex interrelationships coupling EEG and polysomnographic components of the EEG-sleep rhythm. This is particularly relevant for the preterm neonate, in whom a rudimentary sleep cycle has not yet been clearly delineated. Computer analysis can augment the information derived from the visual interpretation of scalp-generated EEG activity. Automated techniques for EEG-sleep analysis have only recently been applied to a neonatal population. Such studies have been limited to full-term rather than preterm infants and rely on conventional methods that assume stationarity of neurophysiologic signals. We describe a computer system that simultaneously compares behavioral and electrographic components of EEG-sleep in a manner that preserves the integrity of the signals over time, while investigating the time- and frequency-dependent relationships among signals. Strategies for on-line and off-line editing, data storage, and off-line signal processing are described. Computational algorithms regarding analyses of EEG power, motility, and cardiorespiratory data are being used to study the ontogeny of EEG-sleep in asymptomatic preterm and full-term neonates. Computer strategies are based on both principles of stationarity and nonstationarity of physiologic signals and are applied depending on the temporal resolution required for specific signal processing needs.

Computer Systems↗
PubMed1990

Acoustic recordings from experimental saccular aneurysms in dogs.

In an effort to isolate and characterize the emission of acoustic signals from saccular aneurysms, we made a series of invasive microphone recordings from experimental aneurysms created on the common carotid arteries of dogs using the vein pouch technique. Using a modified probe microphone, we compared recordings from the common carotid artery before creation of the aneurysm to recordings from the aneurysmal surface, both before and after clip occlusion. We then performed spectral analysis, band-pass filtering, and spectrographic analysis to compare the dominant frequency and width of the frequency range of both the aneurysmal and carotid recorded signals. The aneurysmal signals had a significantly higher dominant frequency (p less than or equal to 0.05) and a significantly wider frequency range (p less than or equal to 0.05) than the carotid signals. Aneurysmal signals recorded under conditions of systemic hypotension had a significantly lower frequency (p less than or equal to 0.05) than aneurysmal signals recorded under conditions of hypertension. Our results support the assumptions that acoustic signals from experimental saccular aneurysms are distinct from those of the parent vessel and that the aneurysmal signal can be characterized using passive microphone recordings.

Animals↗
PubMed1990

[Modified radical mastectomy in the treatment of stage III breast carcinoma].

From 1972 to 1982, 237 patients with stage III breast carcinoma were admitted into our institute. One hundred and eleven cases underwent Auchincloss and Madden modified radical mastectomy (MRM), and the remaining 126 cases received Halsted radical mastectomy (RM). The 5 and 10 years survival rates were 59.17% (61/111), and 36.92% (24/65) in MRM group. The 5 and 10 years survival rates were 53.17% (67/126) and 29.31% (17/58) in RM group. There were no statistically significant differences in the long-term survival rates between the two groups (P greater than 0.05). The authors believe that MRM causing less trauma should be considered in the treatment of stage III breast carcinoma unless in cases with major pectorial muscle involvement or large metastatic axillary nodes.

Adult↗
PubMed1990

[Effects of alpha-human ANF and angiotensin II on aldosterone secretion in vitro from cultured human adrenal tissues and APA tissues].

The effects of the alpha-human ANF and angiotension II on aldosterone secretion in vitro from cultured human adrenal tissues and the aldosterone-producing adenoma (APA) tissues were studied. The fresh human normal adrenal and APA tissues were obtained surgically from five patients. The tissues were mined 1.0 mm3 with scissors, put in DMEM containing 0.25% trypsin, and digested at 37 degrees C for 10 min. Then the tissues were washed with DMEM. The tissues were incubated in 4 ml DMEM containing 10% fetal calf serum at 37 degrees C under 5% CO2 in air for seven days and the aldosterone levels of the culture medium were determined by radioimmunoassay (RIA). The experiments were started on the tenth to fiftieth day of culture. The results show that the effect of alpha-human ANF (10(-8) mol/L final concentration) on aldosterone secretion from normal adrenal tissues was increased at 30 min following a decrement, but do not inhibit the aldosterone secretion in APA tissues. The aldosterone of short duration was inhibit by alpha-human ANF (3 x 10(-8) mol/L or 5 x 10(-8) mol/L) and the aldosterone secretion in a dose-dependent manner in the adenoma tissues. The aldosterone responses were not stimulated by angiotensin II (10(-9) mol/L) in normal adrenal and adenoma tissues, but angiotensin II (5 x 10(-9) mol/L) can stimulate APA tissues. Our results indicate the lack of effect of alpha-human ANF and angiotensin II on APA tissues could be due to the absence of receptors or a variance of the receptors, and/or the enzymes of steroidogenesis were abnormal. These tissues had a marked aldosterone response to ANF and angiotensin II during culturing in one month.

Adenoma↗