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Biomedical subjects

Y J Pan

Publications and source records attributed to Y J Pan.

12 recordsLinked to original sources
PubMed2001

[Studies on chemical structure of polysaccharide from fruit body of Coriolus versicolor].

AIM: To study the structure of polysaccharides from Coriolus versicolor. METHODS: By chromatography a homogeneous polysaccharide B-1-3 was obtained. The structure of B-1-3 was elucidated using the method of total acid hydrolysis, methylation, and 1D and 2D NMR. RESULTS: B-1-3 was found to be mainly composed of Glc by total acid hydrolysis. Its molecular weight was estimated to be 3.16 x 10(5) by HPLC method. Methylation analysis and 1H and 13CNMR indicated the main chain of B-1-3 consisted of beta-D-1,4-Glc and beta-D-1,3-Glc, and branch chains were situated, beta-D-1,3,6-Glc and beta-D-1,4,6-Glc. 1H and 13CNMR also showed that beta-D-Glc-1-->3-beta-D-Glc-beta-D-Glc-1-->4-beta-D-Glc and beta-D-Glc-1-->4-beta-D-Glc-beta-D-Glc-1-->4-beta-D-Glc fragments existed in B-1-3. CONCLUSION: B-1-3 is a glucan which main chain was composed of beta-D-1,4-Glc and beta-D-1,3-Glc beta-D-1,6-Glc.

Glucans↗
PubMed2000

[New triterpenoid saponins from Anemone begoniifolia].

AIM: To study the triterpenoid saponins in the whole plants of Anemone begoniifolia Lévl. et Vant. METHODS: Methanol extraction, normal and reversed phase silica gel column chromatography and various spectral analysis were used to isolate and determine the structures of the triterpenoid saponins. RESULTS: Four triterpenoid saponins were idenetified as: 3-O-beta-D-glucopyranosyl(1-->2)-alpha-L-arabinopyranosyl oleanolic acid 28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranoside (1), 3-O-beta-D-glucopyranosyl (1-->3)-alpha-L-arabinopyranosyl oleanolic acid 28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranoside (2), 23-O-methyl malonyl hederagenin 28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranoside (3) and 3-O-methyl malonyl hederagenin 28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranoside (4). CONCLUSION: Compunds 2, 3 and 4 are new compounds and named as begoniifolides A, B and C, respectively.

Ranunculaceae↗
PubMed1994

Environmental and dietary risk factors for nasopharyngeal carcinoma: a case-control study in Zangwu County, Guangxi, China.

A case-control study was conducted on 88 incident cases of histologically confirmed undifferentiated nasopharyngeal carcinoma (NPC) in Zangwu County, China, and 176 age- sex- and neighbourhood-matched controls. The design of this study was defined after an anthropological survey on living habits in regions of high NPC incidence and the evidence of carcinogenic substances in some commonly consumed preserved foods. Subjects were interviewed regarding living conditions and diet in the year preceding the diagnosis of NPC and, with the help of their families, during childhood and weaning. After adjustment for a living conditions score to eliminate a confounding effect, an increased risk associated with consumption of salted fish during weaning and childhood was confirmed, especially for salted fish in rice porridge. The consumption of leafy vegetables was associated with a reduced risk for NPC, and consumption of melon seeds between 2 and 10 years of age with an increased risk. After multivariate analysis and adjustment according to the living conditions score, the consumption of salted fish in rice porridge before age 2 (OR = 3.8, P = 0.005), exposure to domestic woodfire (OR = 5.4, P = 0.01) and consumption of herbal tea (OR = 4.2, P = 0.02) were found to be independently related to the risk of NPC. The excess risk associated with the use of domestic wood fire increased if there were no windows in the house and with poor ventilation and cooking outside the house in a shack. As well as confirming the importance of the consumption of salted fish in childhood, this study has been the first to provide unequivocal evidence for two other factors implicated in increasing the risk of NPC in China, the adult consumption of traditional medicines (herbal tea) and exposure to domestic wood fumes.

Adult↗
PubMed1993

Diterpenoid Alkaloids from Delphinium caeruleum.

A new minor diterpenoid alkaloid, caeruline, was isolated from DELPHINIUM CAERULEUM Jacq. ex Camb. Its structure was elucidated as 1 on the basis of spectral evidence. Along with this new compound, three known diterpenoid alkaloids were also isolated from this plant and identified as tatsiensine, delcosine, and lycoctonine which had not been found in this herb previously.

Journal Article↗
PubMed1987

Role of renal nerves in compensatory adaptation to chronic reductions in sodium intake.

The aim of this study was to investigate the importance of the renal nerves in adaptation to chronic reductions in sodium intake. Conscious dogs with unilateral (n = 7) or bilateral (n = 4) renal denervation were studied. In dogs studied before and after bilateral denervation, there were no differences in urine volume (UO), Na excretion (UNaV), or fractional reabsorption of Li (FR Li, an index of proximal tubular Na reabsorption) between innervated and denervated kidneys on either normal (80 meq/day) or low Na intake (5 meq/day, 15 days). Plasma renin activity (PRA) was attenuated following denervation on both normal (0.39 +/- 0.06 vs. 0.18 +/- 0.01 ng angiotensin I X ml-1 X h-1) and low Na intake (1.00 +/- 0.06 vs. 0.59 +/- 0.01). In unilaterally denervated dogs the left kidney was denervated and the bladder was split, allowing continuous urine collection from separate innervated and denervated kidneys in the same dog. There was no difference in UO between innervated and denervated kidneys on normal (80 meq/day) or low (7 meq/day, 9 days) Na intake. UNaV averaged 33.6 +/- 1.3 and 37.6 +/- 2.1 meq/day in innervated and denervated kidneys, respectively, on normal Na intake and 3.5 +/- 0.5 and 4.0 +/- 0.4 meq/day in innervated and denervated kidneys on low Na intake. FR Li was not different in denervated compared with innervated kidneys during normal or low sodium intake. Norepinephrine content was reduced by 99 +/- 1% in denervated kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1984

The pathogenic role of the kidney.

The discussions of this article suggest that the pressure natriuresis mechanism of the kidneys is the most important of all long-term regulators of arterial pressure. This is especially so because of the infinite-gain feature of this mechanism, a feature that is explained here. However, experiments have shown that it is not the accumulation of sodium per se in the body that causes hypertension. Instead, it is the increase in extracellular fluid volume that usually accompanies sodium accumulation that increases the arterial pressure. If the increase in fluid volume is prevented, hypertension will not occur despite marked sodium retention. Long-term autoregulation in hypertension plays a very important role for two major reasons: (a) it greatly increases the total peripheral resistance when the cardiac output increases only a small amount, and (b) when it promotes arteriolar constriction, capillary pressure is reduced, which in turns allows a very large proportion of the extracellular fluid to remain in the blood rather than to leak into the interstitium. Marked loss of renal mass usually does not cause hypertension because, as long as there is a proper balance between glomerular filtration capability and tubular reabsorption capability, as little as 10% of the normal kidney mass theoretically can excrete the normal daily load of salt without a significant rise in arterial pressure. However, whenever the ratio of glomerular filtration capability to tubular reabsorption capability falls below normal, salt and water are retained until enough hypertension develops to overcome the deficit in glomerular filtration.

Adaptation, Physiological↗
PubMed1984

Interaction between the natriuretic effects of renal perfusion pressure and the antinatriuretic effects of angiotensin and aldosterone in control of sodium excretion.

Aldosterone has been recognized as an important sodium retaining hormone for many years. Recently we have demonstrated that angiotensin II has a much more powerful antinatriuretic effect than that of aldosterone. The importance of angiotensin II in regulation of sodium excretion has been observed in experiments in which angiotensin II has been infused intravenously or into the renal artery in acute and chronic situations, and in studies involving blockade of angiotensin II formation. In other experiments we have studied the effects of changes in renal perfusion pressure on sodium excretion. While earlier work by others indicated that an acute 10 mm Hg increase in perfusion pressure would increase sodium excretion 60%-70% we observed that a chronic 10 mm Hg change in perfusion pressure would result in a 300% change in sodium excretion. In view of evidence suggesting that changes in the ability of the kidney to excrete sodium normally at normal arterial pressure is an important element in hypertension we studied the effects of aldosterone and angiotensin II on arterial pressure regulation in normal dogs. High physiological levels of each hormone were infused intravenously for several weeks. Both produced sustained hypertension. Aldosterone hypertension was a typical volume loading type with sodium retention, increased blood volume and extracellular fluid volume and a slow rise in arterial pressure. Angiotensin hypertension was a typical vasoconstrictor type with high peripheral resistance, normal or decreased blood volume, decreased cardiac output, a rapid rise in arterial pressure and only initial sodium retention.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗
PubMed1977

Control of extracellular sodium concentration by antidiuretic hormone-thirst feedback mechanism.

The effectiveness of the antidiuretic hormone (ADH)-thirst feedback mechanism to control extracellular sodium concentration was studied in dogs. The design consisted of increasing daily sodium intake from 10 to 200 meq in a group of dogs, first in the normal condition and second with a continuous 24 h/day infusion of an amount of ADH sufficient to maintain urine osmolarity at a maximal level and with fixed water intake. We were therefore able to compare the effectiveness of sodium concentration control in the same dogs with and without feedback control of the ADH-thirst mechanism, the difference in effectiveness being a quantitative measure of the control capability of the system. In the normal condition the increase in sodium intake resulted in a steady-state 2.3% elevation in sodium concentration. With the feedback control of ADH secretion and water intake blocked, the same sodium forcing produced an 11.9% increase in extracellular sodium concentration. The minimum feedback gain for the system calculated from the data is -4.2. We conclude that control of sodium concentration in the intact state is accomplished mainly by the ADH-thirst feedback mechanism.

Animals↗
PubMed1976

The natriuretic and hypotensive effects of potassium.

The chronic effects of potassium loading on sodium balance and related variables were studied in two groups of dogs. The first group was intact except for the presence of indwelling arterial and venous cannulas. On the 1st day, increasing daily potassium intake from a normal level (30 mEq/day) to 200 mEq/day produced a 0.47-mEq increase in plasma potassium with a 56% increase (P greater than 0.01) in sodium excretion in spite of a 58% increase in plasma aldosterone concentration. After 6 days of potassium loading the cumulative negative sodium balance averaged 44 mEq while 22Na space decreased 6.7% (P less than 0.025). In this group arterial pressure did not change measurably. The same experimental protocol was repeated in a second group of dogs that were chronically adrenalectomized and maintained on fixed levels of aldosterone (50 mug/day) and hydrocortisone (1 mg/day). With aldosterone levels held constant the same increase in potassium intake produced a 1st day increase in potassium concentration of 1.20 mEq/liter and 217% (P less than 0.001) increase in sodium excretion. After 5 days of high potassium intake, the cumulative negative sodium balance totaled 84 mEq. Sodium space decreased 7.5% (P less than .005) during the course of the 5-day high potassium intake period. Potassium loading caused a fall in mean arterial pressure in this group; pressure fell from the control level of 110 +/- mm Hg to 87 +/- 4 mm Hg (P less than .001) after 3 days of high intake. By the 5th day of the experiment, pressure stabilized at 96 +/- 3 mm Hg, 13% less than (P less than 0.01) the control level. The results suggest that changes in plasma potassium concentration within physiological limits may have long term effects on sodium balance.

Adrenalectomy↗
PubMedDate not supplied

Experimental aldosterone hypertension in the dog.

Sequential changes in arterial pressure, renal function, body fluid, and electrolyte balance, and several hemodynamic variables were examined during chronic intravenous infusion of aldosterone (14 micrograms/kg/day) in eight conscious dogs maintained on 250 mEq/day sodium and 140 mEq/day potassium intake. Arterial pressure gradually increased and stabilized at 132% +/- 3% (p less than 0.05) of the control value on the 16th day of aldosterone infusion, and cardiac output remained within the normal range. Coinciding with the rise in arterial pressure on the first 2 days of infusion was a marked retention of water and sodium and a rise in extracellular fluid volume and blood volume. Blood volume increased from a baseline value of 64.0 +/- 0.3 ml/kg to 70.7 +/- 1.9 ml/kg (p less than 0.05) on Day 4 and extracellular fluid volume increased from 318 +/- 5 ml/kg to 352 +/- 11 ml/kg (p less than 0.05) on Day 3 of infusion. Both blood volume and extracellular fluid volume remained elevated during infusion. Mean circulatory filling pressure increased from the baseline volume of 9.7 +/- 0.4 mm Hg to an average of 11.7 +/- 0.3 mm Hg (p less than 0.05) during the experimental period. The elevation of mean circulatory filling pressure suggested that this increase may be an essential component in the onset and maintenance of hypertension.

Aldosterone↗