Biomedical subjects

X S Zhou

Publications and source records attributed to X S Zhou.

16 recordsLinked to original sources

PubMed2004

Treatment with leuprolide acetate decreases the threshold of the ventilatory response to carbon dioxide in healthy males.

This investigation was designed to determine if suppression of testosterone alters the ventilatory response to carbon dioxide in the presence of high and low levels of oxygen. Eleven healthy male subjects completed a series of rebreathing trials during wakefulness, before and after treatment with a long-acting gonadotropin-releasing hormone agonist. Five subjects also completed studies during non-rapid eye movement (NREM) sleep. During wakefulness, subjects initially hyperventilated to reduce the partial pressure of carbon dioxide (P(ET,CO2)) below 25 Torr. Subjects then rebreathed from a bag containing a normocapnic (42 Torr), low (50 Torr) or high oxygen (140 Torr) gas mixture. During each trial P(ET,CO2) increased while oxygen was maintained at a constant level. The threshold of the ventilatory response to carbon dioxide was considered to be the point at which minute ventilation began to rise in a linear fashion as P(ET,CO2) increased. The slope of the ventilatory response above the threshold was used as a measure of sensitivity to carbon dioxide. During NREM sleep, hypocapnia was induced via nasal mechanical ventilation. Several trials were completed until the cessation of mechanical ventilation resulted in a central apnoea which demarcated the threshold of the ventilatory response to carbon dioxide. In response to treatment with leuprolide acetate, the threshold measured in wakefulness decreased during carbon dioxide rebreathing in the presence of low (41.05 +/- 0.77 versus 39.40 +/- 0.83 Torr; P = 0.01) and high (46.32 +/- 0.56 versus 44.78 +/- 0.83 Torr; P = 0.01) oxygen levels. An increase in sensitivity (4.82 +/- 0.61 versus 7.17 +/- 1.20 l min(-1) Torr(-1); P = 0.02) was also observed during rebreathing in the presence of high but not low oxygen levels. The increase in sensitivity was accompanied by an increase in carbon dioxide production. The findings observed during NREM sleep were similar to those observed during wakefulness, since the P(ET,CO2) that demarcated the threshold was decreased after leuprolide treatment (42.1 +/- 0.6 versus 39.6 +/- 0.6 Torr; P = 0.002). Additionally, the decrease in P(ET,CO2) required to induce an apnoea was greater after treatment with leuprolide (2.56 +/- 0.25 versus 4.06 +/- 0.29 Torr; P = 0.004). We conclude that suppression of testosterone decreases the threshold of the ventilatory response to carbon dioxide during both wakefulness and sleep.

Adult↗

PubMed2002

Effect of testosterone on the apneic threshold in women during NREM sleep.

The hypocapnic apneic threshold (AT) is lower in women relative to men. To test the hypothesis that the gender difference in AT was due to testosterone, we determined the AT during non-rapid eye movement sleep in eight healthy, nonsnoring, premenopausal women before and after 10-12 days of transdermal testosterone. Hypocapnia was induced via nasal mechanical ventilation (MV) for 3 min with tidal volumes ranging from 175 to 215% above eupneic tidal volume and respiratory frequency matched to eupneic frequency. Cessation of MV resulted in hypocapnic central apnea or hypopnea depending on the magnitude of hypocapnia. Nadir minute ventilation as a percentage of control (%Ve) was plotted against the change in end-tidal CO(2) (Pet(CO(2))); %Ve was given a value of zero during central apnea. The AT was defined as the Pet(CO(2)) at which the apnea closest to the last hypopnea occurred; hypocapnic ventilatory response (HPVR) was defined as the slope of the linear regression Ve vs. Pet(CO(2)). Both the AT (39.5 +/- 2.9 vs. 42.1 +/- 3.0 Torr; P = 0.002) and HPVR (0.20 +/- 0.05 vs. 0.33 +/- 0.11%Ve/Torr; P = 0.016) increased with testosterone administration. We conclude that testosterone administration increases AT in premenopausal women, suggesting that the increased breathing instability during sleep in men is related to the presence of testosterone.

Administration, Cutaneous↗

PubMed2001

[Decolorization and isolation of recombinant hirudin expressed in the methylotrophic yeast Pichia pastoris].

Schemes for decolorization of broth and isolation of recombinant hirudin from the fermentation supernatants of recombinant yeast Pichia pastoris were developed to remove a great deal of non-desired proteins and coloring matters. Based on the stability of hirudin, heating is desirable to pre-treat the fermentation broth. Several different column chromatographies, including anion-exchange, cation-exchange, hydrokyapatite adsorption, hydrophobic interaction, gel filtration and their combination were investigated on the efficiencies of decolorization and isolation. Among these methods, the combination of cation-exchange and anion-exchange was found to be a success in both decolorization and isolation of hirudin.

Chromatography, Gel↗

PubMed2000

Regenerative growth of respiratory bronchioles in dogs.

Loss of lung units due to pneumonectomy stimulates growth of the remaining lung. It is generally believed that regenerative lung growth involves only alveoli but not airways, a dissociated response termed "dysanaptic growth." We examined the structural response of respiratory bronchioles in immature dogs raised to maturity after right pneumonectomy. In another group of adult dogs, we also examined the effect of preventing mediastinal shift after right pneumonectomy on the response of respiratory bronchioles. In immature dogs after pneumonectomy, the volume of the remaining lung increased twofold, with no change in volume density, numerical density, or mean diameter of respiratory bronchiole, compared with that in the control lung. The number of respiratory bronchiole segments and branch points increased proportionally with lung volume. In adult dogs after pneumonectomy, prevention of mediastinal shift reduced lung strain at a given airway pressure, but lung expansion and regenerative growth of respiratory bronchiole were not eliminated. We conclude that postpneumonectomy lung growth is associated with proliferation of intra-acinar airways. The proportional growth of acinar airways and alveoli should optimize gas exchange of the regenerated lung by enhancing gas conductance and mixing efficiency within the acinus.

Animals↗

PubMed2000

Effect of gender on the development of hypocapnic apnea/hypopnea during NREM sleep.

We hypothesized that a decreased susceptibility to the development of hypocapnic central apnea during non-rapid eye movement (NREM) sleep in women compared with men could be an explanation for the gender difference in the sleep apnea/hypopnea syndrome. We studied eight men (age 25-35 yr) and eight women in the midluteal phase of the menstrual cycle (age 21-43 yr); we repeated studies in six women during the midfollicular phase. Hypocapnia was induced via nasal mechanical ventilation for 3 min, with respiratory frequency matched to eupneic frequency. Tidal volume (VT) was increased between 110 and 200% of eupneic control. Cessation of mechanical ventilation resulted in hypocapnic central apnea or hypopnea, depending on the magnitude of hypocapnia. Nadir minute ventilation in the recovery period was plotted against the change in end-tidal PCO(2) (PET(CO(2))) per trial; minute ventilation was given a value of 0 during central apnea. The apneic threshold was defined as the x-intercept of the linear regression line. In women, induction of a central apnea required an increase in VT to 155 +/- 29% (mean +/- SD) and a reduction of PET(CO(2)) by -4.72 +/- 0.57 Torr. In men, induction of a central apnea required an increase in VT to 142 +/- 13% and a reduction of PET(CO(2)) by -3.54 +/- 0.31 Torr (P = 0.002). There was no difference in the apneic threshold between the follicular and the luteal phase in women. Premenopausal women are less susceptible to hypocapnic disfacilitation during NREM sleep than men. This effect was not explained by progesterone. Preservation of ventilatory motor output during hypocapnia may explain the gender difference in sleep apnea.

Adult↗

PubMed1993

Computed tomography in predicting the efficacy of oral cholelitholysis with bile acids.

The efficacy of oral cholelitholytic therapy with chenodeoxycholic acid (CDCA) and ursodeoxycholic acid (UDCA) in 137 patients with gallstones was studied in relation to their CT patterns. The best dissolving results were obtained in patients with the stones in isodensity and faint category (< 50 Hu) on CT. The stones with high density or heterogeneous calcification on CT were insoluble, and therefore, were contraindicated for oral cholelitholytic therapy. The attenuation value of stones was classified as complete dissolution ranged from -2 to 35 Hu (14 +/- 12 Hu, n = 13), and their upper limit of 95 percentiles was 33.4 Hu. CT analysis improved the predictability of dissolving gallstones in comparison with plain abdominal radiography or oral cholecystography (OCG). The complete dissolving rate increased from 9.49% (13/137) in patients selected by classic X-ray to 40.7% (11/27) in isodensity category on CT. Besides, radiolucent gallstones, which showed no obvious filling defect on OCG but distinct echo and shadow on B-type ultrasonography, were also insoluble.

Adult↗

PubMed1991

Plasma shock wave lithotripsy of gallstones in vitro. Animal experiments and clinical application.

It is sometimes very difficult to extract a huge impacted stone through the T-tube fistulous tract by conventional techniques with choledochoscope. To simplify the procedure, a lithotriptor PSW-G type using plasma shock wave to disintegrate the stone was designed. The efficacy to fragmentate stone was investigated both in vitro and in vivo. Stones can be shattered into pieces less than 3 mm in diameter in about 30 times of spark with lower energy ranging from 1.7-3.4 kV and 1-3 J. Animal experiments were carried out to prove the safety of the lithotriptor. There was neither interference with the cardiovascular and respiratory systems nor obvious damage to the adjacent tissue where plasma shock wave applied to break stones. Six patients with retained calculi impacted both in extra- and intra-hepatic duct were successfully treated by plasma shock wave lithotripsy. It appears very useful in dealing with a huge impacted stone in the biliary tract.

Animals↗

PubMed1990

A retrospective study on diagnosis and treatment of severe acute pancreatitis.

Severe acute pancreatitis is highly controversial on its diagnostic criteria, the optimum time for surgery, the selection of surgical procedures, and the prevention and treatment of complications. We treated 40 patients with severe acute pancreatitis from July 1983 to July 1988. The comparison of clinical and laboratory data of severe acute pancreatitis and mild acute pancreatitis showed that in some patients neither Ranson's nor Bank's criteria are reliable in classifying or predicting the severity of the disease. The coexistence of acute peritonitis and bloody ascites with elevated amylase level is very helpful to identify the local conditions of pancreatic necrosis and hemorrhage. We suggest early operation (within 48 hours) be applied in severe acute pancreatitis. In our series, five types of surgical procedures were used. We consider that proper treatment of acute respiratory distress syndrome (ARDS) is most important in the management of severe pancreatitis.

Abscess↗

PubMed1989

[Value of endometrial aspiration cytology in assessing endometrial status].

Cytologic findings of endometrial aspiration from 135 women was correlated with pathologic diagnosis of endometrium. The results indicate that different endometrial changes, such as hyperplasia, carcinoma and other malignant endometrial lesions, different phases of normal menstrual cycle and senile atrophy can be distinguished by endometrial cytology. The author suggests that aspiration cytology may serve as a supplement to the biopsy or curettage in the assessment of the status of the endometrium.

Adult↗

PubMed1987