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Biomedical subjects

S Z Jiang

Publications and source records attributed to S Z Jiang.

17 recordsLinked to original sources
PubMed2001

Effect of repeated +Gz exposures on energy metabolism and some ion contents in brain tissues of rats.

BACKGROUND: It has been demonstrated that during +Gz exposure cerebral blood flow is significantly reduced, resulting in brain ischemia. In pilots, such conditions could recur several times during centrifuge training and combat maneuvers and could possibly cause reversible change in brain energy metabolism. HYPOTHESIS: In rats there is an association between +10 Gz exposure and the decreased brain metabolism, as indicated by decreased adenosine triphosphate (ATP) and ATPase activity, and increased adenosine diphosphate (ADP) and lactate, etc. The aim of the present study was to examine the time course and recovery of brain energy metabolism, lactate, ATPase activity, Na+, K+, Ca2+ and water contents after three +10 Gz exposures in rats. METHODS: There were 64 male Sprague-Dawley rats that were restrained and placed on an animal centrifuge. They were divided into groups of 16. Control rats were exposed to +1 Gz and experimental rats were exposed to +10 Gz three times each for 3 min at 30-min intervals. After being euthanized, rat brains were removed 0 h, 1 h, or 6 h after the last centrifuge run. Brain samples were analyzed for energy metabolism, lactate, Na+-K+-ATPase activity, water and electrolytes contents. RESULTS: The cortical ATP content, Na+-K+-ATPase and lactate dehydrogenase (LDH) activities decreased significantly, whereas the cortical ADP, adenosine monophosphate (AMP) and lactate contents increased significantly 0 h after three +10 Gz exposures, as compared with those of control. The ATP, ADP, and AMP contents returned to their control levels 1 h after the +10 Gz exposures, however, lactate content, Na+-K+-ATPase and LDH activities delayed recovery 6 h after +10 Gz exposures. The cortical K+ content increased significantly 0 h and 1 h after +10 Gz exposures, and returned to the control level 6 h after +Gz exposures. Na+ and water contents increased significantly 1 h and 6 h after the +10 Gz exposures. There was no significant change in Ca2+ content after +Gz exposures. CONCLUSIONS: Three +10 Gz (3 min each) exposures were associated with transient depression of brain metabolism as indicated by a decrease in ATP, Na+-K+-ATPase activity, and an accumulation of lactate, and disturbance of ion homeostasis. It is suggested that a causal relationship might exist between repeated high +Gz exposures and brain metabolism.

Acceleration↗
PubMed2001

Changes of human cerebral bottom arterial hemodynamics during 21 d head-down tilt (-6 degrees) bed-rest.

OBJECTIVE: To investigate the change of human cerebral bottom arterial hemodynamics during 21 d simulated weightlessness. METHOD: 21 d -6 degrees head-down tilt bed rest (HDT) were used to simulate weightlessness. 6 healthy male, aged 24.8 +/- 6.1 served as subjects. Systolic blood velocity (Vs), diastolic blood velocity (Vd), mean blood velocity (Vm), pulsatility index (PI), resistance index (RI) and other indices of middle cerebral arteries (MCA), anterior cerebral artery (ACA) and posterior cerebral artery (PCA) were measured by transcranial ultrasound Doppler before HDT and on day 0 (D0), 1, 3, 7, 10, 21 of HDT. HUT +75 degrees 20 min orthostatic tolerance tests were done on day -1, 10, and 21 of HDT. RESULT: During HUT +75 degrees 20 min orthostatic tolerance test on day 10 and 21 of HDT, the average standing time were shorter than that of the pre-HDT values (P<0.05). On day 3 and 21 of HDT, Vs of right MCA reduced significantly than pre-HDT (P<0.05 or P<0.01). On day 1, 3, 7, 10 and 21 of HDT, Vs of right MCA were obviously lower than that on D0 (P<0.05 or P<0.01). Left MCA Vs on D0 increased significantly than that of pre-HDT (P<0.05), and both were significantly higher than those of the 3rd day of HDT (P<0.01). Right MCA Vm on the 3rd and 21st day of HDT were significantly lower than those pre-HDT and D0 (P<0.05 or P<0.01). On day 10 of HDT, Vm of right MCA were significantly reduced than that on D0 (P<0.05). Both MCA bilateral velocity difference (right Vm-left Vm) on the 3rd, 10th, 21st day of HDT, and MCA inter-hemispheric asymmetry index on the 10th, 21st day of HDT were significantly lower than that of pre-HDT (P<0.05 or P<0.01). CONCLUSION: 21 d HDT bed-rest decreased orthostatic tolerance, Vs of both side MCA, and Vm of right MCA. Lower Vs of both side MCA and the inter-hemispheric asymmetry of MCA during HDT maybe responsible, in part, for the increased risk of orthostatic intolerance.

Adaptation, Physiological↗
PubMed2001

[Changes of cardiac function during 21 d head-down tilt bed rest and the effect of lower body negative pressure in the last week].

OBJECTIVE: To investigate the change of cardiac function during 21 d head-down tilt (HDT) bed rest and the effect of lower body negative pressure (LBNP) in the last week in human. METHOD: 12 healthy male served as subjects which were randomly divided into control and LBNP groups, with 6 in each group. All of them were exposed to -6 degrees HDT for 21 d. The LBNP group received -4.0 kPa LBNP training 1 h/d in the last week of the test. The cardiac pump function and cardiac systole function were measured before, during and after HDT. RESULT: Cardiac output, cardiac index and stroke volume decreased significantly, whereas total peripheral resistance, pre-ejection period (PEP), isovolumetric contraction time/left ventricular ejection time (LVET) and PEP/LVET increased significantly during HDT in both control and LBNP groups, compared to pre-HDT values, and they returned to normal level on day 2 post HDT. PEP and PEP/LVET in LBNP group were significantly higher than those in control group on day 21 of HDT and day 2 post HDT. CONCLUSION: The reduction of cardiac pump function and cardiac systole function induced by 21 d HDT could not be prevented by LBNP training in the last week of 21 d HDT.

Adolescent↗
PubMed2001

[Human dynamic response to landing impact in selected body orientations].

Objective. To study changes of human dynamic response to landing impact in selected body orientations. Method. Five healthy young men were exposed to 10 G, 50 ms half-sine acceleration pulses. The angle included between human head-ilium axis and impact force direction was 30 degrees-70 degrees. The acceleration responses at head, shoulder, chest and ilium of the subjects were recorded along head-ilium and chest-back directions. Result. Within limits of the experiments, the minimum peak response at the head along head-ilium direction was 10.36 +/- 2.44 G at 50 degrees, and the maximum was 18.07 +/- 3.29 G at 70 degrees. The minimum peak response at the chest along head-ilium direction was 10.39 +/- 3.97 G at 70 degrees, and the maximum was 15.42 +/- 3.61 G at 60 degrees. The minimum peak response at the head along chest-back direction was 7.58 +/- 1.18 G at 30 degrees, and the maximum was 18.89 +/- 1.85 G at 70 degrees. The minimum peak response at the chest along chest-back direction was 7.21 +/- 1.99 G at 30 degrees, and the maximum was 17.67 +/- 2.16 G at 70 degrees. Conclusion. It was inferred that the best body orientation angle for landing impact might be 50 degrees.

Acceleration↗
PubMed2001

[Changes of cerebral blood flow during 21 d head-down tilt bed rest and the effect of lower body negative pressure during the last week].

Objective. To investigate the changes of cerebral blood flow (CBF) during 21 d head-down tilt (HDT) bed rest and the effect of lower body negative pressure (LBNP) in the last week. Method. Twelve healthy male subjects were randomly divided into control and LBNP groups, with 6 in each group. All of them were exposed to -6 degrees HDT for 21 d. The LBNP group received -4.0 kPa LBNP training 1 h/d in the last week of HDT while the control group did not. CBF and cerebral vascular resistance were measured by rheoencephalogram in pre-HDT, day 3, 10 and 21 of HDT. Result. In control group, left cerebral I quadrant area and inrush velocity decreased significantly during HDT, and left cerebral delta Gy wave crest height decreased significantly, whereas left cerebral resistance index increased significantly on day 3 and 21 of HDT as compared to those of pre-HDT. In LBNP group, left cerebral I quadrant area decreased significantly, and left cerebral delta Gy wave crest height and inrush velocity tended to decrease on day 3 and 21 of HDT, whereas left cerebral resistance index increased significantly during HDT as compared to those of pre-HDT. There were no significant differences between above indexes in control group and LBNP group. Conclusion. It is suggested that 21 d HDT may increase cerebral vascular resistance and decrease CBF, which can not be prevented by LBNP training in the last week of 21 d HDT.

Adult↗
PubMed1999

[Variation of several volume regulating hormones during 21 d - 6 degrees head-down bed rest].

UNLABELLED: Objective To investigate variations of plasma renin activity, a prostaglandin I2 (PGI2) during 21 d -6 degrees head-down tilt (HDT) with and without lower body negative pressure (LBNP). METHOD: -6 degrees head-down tilt for 21 d were used to simulate weightlessness. 12 healthy male, aged 23.7 +/- 5.0, were equally and randomly divided into control group (CON) and LBNP group. The latter subjected to LBNP (-30 mm Hg, 1 h/d) in the last week of HDT. Samples of plasma were taken before HDT and on the 2nd, 4th, 11th and 22nd day during HDT. RESULT: Compare to control levels, Ald declined significantly on the 2nd (CON -30%, P < 0. 05; V. S. LBNP -38%, P < 0.01), and increased significantly on the 11th day (CON +30%, P < 0.05; LBNP +48%, P < 0.01). PRA reached peak value on the 4th day (P < 0.05), and declined to below the control level on the 22nd day. PGI2 increased constantly during HDT, and increased significantly on the 22nd day (CON P < 0.01), 11th, 22nd (LBNP P < 0.05). No apparent difference was found between groups after LBNP concerning PRA and Ald; and PGI2 didn't increase further in LBNP group. Conclusion HDT induced a timely increasing in PRA and Ald, constant increasing in PGI2.

Adaptation, Physiological↗
PubMed1999

[Effect of extremity cuffs as a countermeasure against the cardiovascular deconditioning during 21 d head-down bedrest].

OBJECTIVE: To affirm the protective effect of inflated cuffs. METHOD: The protective effect against the cardiovascular deconditioning of inflated cuffs on the upper parts of thighs and arms during the 1st through 10th days of 21 d bedrest has been reported previously. The effect of the cuffs during the rest of the 21 d bedrest were studied in this paper. Five subjects in cuffs group whose orthostatic tolerance were well maintained continued bed rest for 7 d without inflated cuffs. For the last 4 days of this period, inflated cuffs were again applied. Orthostatic tolerance of subjects in cuffs group with and without cuffs were measured. RESULT: Two of the five subjects suffered orthostatic intolerance on the 17th day. No sign of orthostatic intolerance were observed by the end of bedrest. CONCLUSION: (1) the cardiovascular deconditioning developed when inflated cuffs were not used, and (2) the use of inflated cuffs for 4 d improves the orthostatic tolerance.

Adolescent↗
PubMed1999

[Countermeasuring effect of lower body negative pressure against orthostatic intolerance induced by 21 d -6 degrees head down tilt in humans].

Objective. To investigate whether LBNP during 21 d -6 degrees head-down tilt (HDT) would modify orthostatic tolerance. Method. 12 healthy males, age 23.7 +/- 5.0, were exposed to -6 degrees HDT for 21 d. 6 of them received -4.0 kPa LBNP sessions for 1 h/d from 15th day to 21st day of HDT. The other 6 served as control. HUT + 75 degrees, 20 min orthostatic tolerance test were done before, on day 10 and on day 21 of HDT. Result. During HUT + 75 degrees, 20 min orthostatic tolerance test on day 10 of HDT, 5 subjects of the control group and 4 of the LBNP group presented presyncopal or syncopal signs and symptoms, the average standing time of both groups were shorter than those of the pre-HDT (p<0.05). During HUT + 75 degrees, 20 min orthostatic tolerance test on day 21 of HDT, 5 subjects of the control group and one subject of the LBNP group presented presyncopal or syncopal signs and symptoms, the average standing time of control group reduced significantly as compared with those of pre-HDT(P<0.05), also significantly shorter than those of LBNP group (P<0.05). Conclusion. The present study clearly shows that the use of LBNP could alleviate the bed rest-induced orthostatic intolerance.

Adult↗
PubMed1992

Identification and characterization of a 30K glycoprotein of herpes simplex virus type 2.

A herpes simplex virus type 2 (HSV-2) type-specific monoclonal antibody (MAb), CH-A9, precipitated a glycoprotein with an M(r) of approximately 30,000 (g30K) from extracts of HSV-2-infected BHK cells labelled with [3H]leucine, [14C]fructose or [3H]glucosamine. The M(r) of this glycoprotein is lower than those of other HSV glycoproteins. Immunoassays of BHK cells infected with HSV-1-HSV-2 intertypic recombinants localized the gene encoding the target antigen of MAb CH-A9 to the unique long (UL) region at map units 0.490 to 0.564. Tunicamycin effectively inhibits N-linked glycosylation of g30K, which suggests that g30K may be modified by addition of N-linked oligosaccharides and that the amino acid sequence may contain Asn-X-Ser or Asn-X-Thr. The g30K was also purified on an immunoadsorbent column consisting of MAb CH-A9 linked to Sepharose 4B and was shown to be an HSV-2 type-specific antigen by indirect ELISA. The glycoprotein could induce HSV-2 type-specific neutralizing antibody in BALB/c mice. This evidence suggests that g30K may be a novel glycoprotein of HSV-2.

Animals↗
PubMed1992

Preparation and characterization of the monoclonal antibodies against Japanese encephalitis virus.

Six mouse monoclonal antibodies (MoAbs) against Japanese encephalitis virus (JEV) were prepared and analyzed with indirect immunofluorescence assay (IFA), enzyme linked immunosorbent assay (ELISA), haemagglutination inhibition test (HI), neutralization test (NT), antibody dependent cell mediated cytotoxicity (ADCC) assay, antigenic site specific analysis and relative affinity measurement. These MoAbs could be divided into three classes by indirect immunofluorescence cross reactivity among four flaviviruses, 2H4, 2F2, and nG2 were type specific; 2D2 and mC3 were subgroup specific; and mG9 was family specific. 2H4 and 2F2 had higher neutralization activity, 2D2 and mC3 had the function of inducing ADCC effect, mG9 had higher titer in HI. The six MoAbs recognized five antigenic sites on JEV envelope glycoprotein, 2H4 and 2F2 recognized the same or very similar antigenic site and their relative affinity was ranked as: nG2 > 2H4 > 2D2 > mG9 > 2F2 > mC3.

Animals↗
PubMed1991

Effects of hyperthermia and/or hyperglycemia on pH and pO2 in well oxygenated xenotransplanted human sarcoma.

The heat-induced interdependent changes of tumor blood flow, pO2, and pH decisively influence the therapeutic effect of hyperthermia (HT). This fact has induced us to determine simultaneously the frequency distribution of local pO2 values and the intratumoral pH in a xenotransplanted human sarcoma cell line at a normal blood glucose level and under hyperglycemic conditions before, during, and after HT. Two groups, one of 10 and one of 9 congenitally athymic nude rats with a subcutaneously implanted S117 human sarcoma into the right hind paw (mean tumor volume 5.3 cm3) were treated with local waterbath HT (tumor temperature 43 degrees C, 1 hr) alone or in combination with i.p. glucose injections (6 g/kg, 2 hr before the onset of HT). Tumor oxygenation remained improved throughout HT. Tumor pH did not decrease during HT. Hyperglycemia alone elicited a decrease of intratumoral pH and pO2, probably mainly due to hemoconcentration. The additional warming of the tumors (43 degrees C) during hyperglycaemia did not further decrease pO2 and pH. Silver stained sections of the tumors showed only a few very small necrotic areas, even in tumors of volumes up to 8 cm3. Our results indicate a well oxygenated tumor. In contrast to most tumors studied so far, hyperthermia in this tumor induces not only an initial increase of oxygenation but a lasting elevation of mean tumor pO2 for the duration of HT (up to 60 min).

Animals↗
PubMed1989

Passive protection of mice, goats, and monkeys against Japanese encephalitis with monoclonal antibodies.

Six monoclonal antibodies (McAbs) against Japanese encephalitis virus (JEV) were tested for passive protection in JEV-infected mice, goats, and rhesus monkeys. mG9 and nG2 had no protective effect; mG3 and 2D2 had some protective effect, but not sufficient to be of therapeutic significance; and 2H4 and 2F2 had excellent protective efficacy in mice even 120 hr after infection when most of the mice in the virus control group were sick. The mixture of 2H4, 2F2, mC3 (M-McAb), and their F(ab')2 fragments showed excellent protection in mice, goats, and monkeys and was safe. The protective effects of McAbs correlated with their neutralization titers, but cytotoxicity-mediated activities also played a role in protection.

Animals↗
PubMed1988

Effects of combined resistive loading on the respiratory pattern and the subject's perception.

The physiological and psychophysical effects of combined flow resistive loads were studied systematically by using the Multistage Evaluation Scale (MES), determining the number of Just Noticeable Difference (JND) steps, and constructing equivalent resistive-load-sensation contours. During combined resistive loading, the relative changes of inspiratory and expiratory peak flow rate (VImax/VEmax) were related to both the JND step number and the inspiratory versus expiratory resistance ratio (IR/ER). However, the ratio VImax/VEmax was related to the IR'/ER' ratio only. The subject's perception of combined loads differing both in intensity and IR/ER ratio could be well depicted by the equivalent resistive-load-sensation contours. Hence we could define a model for predicting the physiological and psychophysical effects of various resistive loading conditions.

Humans↗
PubMed1988

Multistage evaluation scale, differential threshold steps and equivalent sensation contours of respiratory flow-resistive load sensation.

This paper presents and discusses the methodology and results of studies on respiratory sensation by using a fuzzy set category judgement model and applying the concept of just noticeable difference (JND) step and equivalent sensation. A new kind of category scale, the multistage evaluation scale (MES), based on a fuzzy set category judgement model for quantifying respiratory sensory magnitude has been put forward and verified in 37 subjects. The perceived magnitude of added resistance estimated using MES could reflect properly the difference in sensory perception caused by added loads with equal intensity but applied to different phases of the breathing cycle. In addition, the psychophysical function obtained conforms to the Stevens' power law. On the contrary, the classical category scale does not possess some of these attributes. In 9 subjects, we determined that the sensory continuum corresponding to either inspiratory or expiratory added resistive load, ranging 10-500 mm H2O.1(-1).s, consisted of 6 or 7 JND steps. The sensory magnitude corresponding to each step was estimated by the MES. Relating the results of JND step measurements with that of magnitude estimation using MES, we could elucidate systematically the relationship between perceived magnitude and discrimination for respiratory sensation. In 13 subjects, the equivalent respiratory resistive load sensation contours of 2, 3 and 4 JND step above basal level, respectively, were obtained through experimentation and by quadratic polynomial approximation of experimental data. The results suggest that as regards the human tolerance to various added resistive loads the combined resistive load is the most tolerable among the three; the expiratory, the least. The equivalent sensation contour can be used to predict the changes in respiratory sensation determined by both the intensity of the total added load and the ratio of inspiratory versus expiratory load. In brief, we have proposed a new way to elucidate the physiological and psychophysical effects of various added resistive loads.

Humans↗