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Biomedical subjects

S W Zhang

Publications and source records attributed to S W Zhang.

At least 19 recordsLinked to original sources
PubMed1999

Down-regulation of beta1,4-galactosyltransferase gene expression by cell-cycle suppressor gene p16.

Beta1,4-Galactosyltranferase (beta1,4GT, EC 2.4.1.38) is one of the key enzymes controlling the biosynthesis of complex-type oligosaccharides, and is also one of the best-studied glycosyltransferases. To study the molecular mechanisms involved in the regulation of beta1,4GT gene expression, we transfected cell-cycle suppressor gene p16 into A549 cell line (in which p16 is deleted), measured beta1,4GT gene expression by Northern blot hybridization, and evaluated its activity. It was found that p16 could down-regulate beta1,4GT gene expression and its activity. However, p16 decreased cell surface beta1,4GT activity more than total activity. beta1,4GT mRNA stability was also assayed. It was found that p16 could not influence beta1,4GT mRNA stability.

Cell Cycle↗
PubMed1999

Honeybee memory: navigation by associative grouping and recall of visual stimuli.

Studies of navigation in bees and ants are beginning to reveal that foraging insects traveling repeatedly to a food source navigate by using a series of visual images of the environment acquired en route (Collett, 1996; Collett et al., 1993; Judd & Collett, 1998; Wehner et al., 1990, 1996). By comparing the currently viewed scene with the appropriate stored image, the insect is able to ascertain whether or not it is on the correct path and make any necessary corrections. If a bee happens to forage at more than one site, then she needs not only to memorize a separate set of images for each route that she has learned but also to retrieve the set of images that is appropriate to each route. Here we examine the bee's capacity to learn and later retrieve from memory two different sets of visual stimuli. Bees were trained to fly through a compound Y-maze where they were presented alternately with two different sequences of visual stimuli on their route to a food reward. We find that bees can indeed store two different sequences of images simultaneously. Furthermore, the trained bees are able to classify the memorized images into two groups, one pertaining to each three-stimulus set. Exposure to any of the images pertaining to one set triggers recall of all of the other images associated with that set. Associative grouping and recall of visual stimuli, demonstrated here for the first time in honeybees, provide an effective means of retrieving the appropriate navigational information from memory.

Animals↗
PubMed1998

Restoration of the p16 gene is related to increased radiosensitivity of p16-deficient lung adenocarcinoma cell lines.

To assess the role played by p16 gene expression in the radiosensitivity of human lung cancers, we transferred exogenous p16 genes into p16-deficient H460 and A549 lung adenocarcinoma cell lines and compared the cell survival curve in vitro after irradiation. The surviving fraction of the p16-transfected A549p16 and H460p16 cells that expressed exogenous p16 mRNA or protein was lower than those of the parental and negative control cells. The rapid exit of the p16-transfected cells from the G2/M phase in the cell cycle, both before and after irradiation, possibly contributes to the increased radiosensitivity of our experimental p16-transfected lung adenocarcinoma cell lines. We conclude that exogenous p16 gene may be another important factor controlling the intrinsic cellular radiosensitivity of cancer.

Adenocarcinoma↗
PubMed1997

Visual control of honeybee flight.

Recent research has uncovered a number of different visual cues which bees use for controlling and stabilising flight. Bees flying through a tunnel maintain equidistance to the flanking walls by balancing the speeds of the images of the two walls. This strategy enables them to negotiate narrow passages or to fly between obstacles. The speed of flight in the tunnel is controlled by holding constant the average image velocity as seen by the two eyes. This mechanism prevents potential collisions by ensuring that the bee slows down when it flies through a narrow passage. Bees landing on a horizontal surface hold constant the image velocity of the surface as they approach it, thus automatically ensuring that flight speed is close to zero at touchdown. The movement-sensitive mechanisms underlying these various behaviours differ qualitatively as well as quantitatively, from those that mediate the well-investigated optomotor response. Flight thus appears to be co-ordinated by a number of visuomotor systems acting in concert.

Animals↗
PubMed1997

The effects of combined treatments with low hyperthermia and bleomycin on survivals of murine L cells.

Modification effects of low hyperthermia (40 degrees C) on cellular chemosensitivity to bleomycin (BLM), and of BLM on thermosensitivity (40 degrees C) were investigated in cultured murine L cells with simultaneous or sequential treatments of these two agents. The heating of L cells at 40 degrees C up to 6 hours resulted in no remarkable lethal damage. Treatment with low hyperthermia followed by BLM for 4 hours showed no more than additive effect. However, a significant chemical (BLM) enhancement effect on the cellular thermosensitivity was observed by the treatment with BLM for 4 hours prior to the low hyperthermia at 40 degrees C. No appreciable thermal enhancement effect on the cellular chemosensitivity to BLM was shown by preheating at 40 degrees C for 3 hours, while post-heating at 40 degrees C showed a significant thermal enhancement effect as well as in the simultaneous treatments. The cell phase response to BLM was levelled in the clinical range of the doses. It is possible that the repair of sublethal damage (SLDR) from treatment with BLM was inhibited by 40 degrees C post-heating and this SLDR was completed at 3 hours of the interval at 37 degrees C between BLM and 40 degrees C heating.

Animals↗
PubMed1996

Maze learning by honeybees.

This study examines whether honeybees can learn to fly through complex mazes, in the presence or the absence of specific visual cues. The results are summarized as follows: 1. Bees can learn to fly through a complex maze by following a trail of colored marks. 2. Bees, initially trained to follow color marks through an initial part of the maze, are immediately able to use the same sign-tracking cue to find their way through the rest of the maze, which is unfamiliar to them. 3. Bees trained to follow color marks through a particular maze can use the same cue to negotiate a novel maze. 4. Bees trained to use a particular color to negotiate a maze can immediately use a novel color to negotiate the same maze or even a novel maze. 5. After learning to negotiate a maze by following colored marks, bees can find their way through the maze even when the marks are removed, albeit at reduced levels of accuracy. Thus, the trained bees do not rely solely on sign-tracking to find their way through the maze: they also acquire a spatial memory of the maze or at least a sequence of motor commands describing the correct path through it. 6. Bees can learn to use color as a signal even when it indicates the path through the maze in a symbolic way, for example, blue indicating a turn to the right and green a turn to the left. 7. Bees can learn an unmarked maze. Performance under these conditions is poorer than when marks are provided, but is still significantly better than chance level. 8. Control experiments rule out the use of external landmarks in all of these situations.

Animals↗
PubMed1995

[Study on treatment of infectious shock with recipe of liqi huoxue and kaibi gutuo].

Based on the pathogenesis of infectious shock which were stagnation of Qi, blood stasis, impairment of body resistance and trends to collapse, a series of new preparations of traditional Chinese Medicine was developed, Injection Kangjue Tongmai, Injection Yiqi Jiuyin and Injection Yiqi Huiyang, which could Liqi Huoxue and Kaibi Gutuo (regulate the flow of Qi, promote blood circulation, strengthen the body resistance and remit collapse), the result of 183 cases of infectious shock treated with them showed that the mortality was 4.37%, significantly lower than that of control group (23.0%). All three injections could rapidly elevate blood pressure and stabilize it for prolonged time, increase renal blood flow and lower blood viscosity. In animal experiment, the injections reduced lipid peroxide of vital organs, stabilized bio-membrane, protected the cell structure and maintained their normal functions.

Adult↗
PubMed1994

[The effect of hydrocortisone or dexamethasone on human erythrocyte membrane insulin receptor].

It is shown that the maximum specific binding rate (B/T) of erythrocyte membrane receptor to insulin was significantly decreased, the concentration of plasma insulin was significantly increased and the level of plasma glucose was not obviously changed after taking hydrocortisone (1.25mg/kg) or dexamethasone (37.5 micrograms/kg) orally. Scatchard analysis showed that decreased B/T was not mainly due to the change of the affinity or number of foci of insulin receptors, as no significant influence on insulin binding was found in vitro. The data suggested that the effect of both drugs on insulin receptor was multifactorial, including the secretion of insulin as well as the combination of insulin to its receptors.

Adult↗
PubMed1994

[Effect of jiutuo II injection on shock model of superior mesenteric artery occlusion in rabbit].

Tang's SMAO method was adopted to produce shock model to observe the efficacy of the Jiutuo II(JTII) intravenously given. It was found that JTII could normalize the BP rapidly, which were superior to that of Dopamine and NS groups (P < 0.05, P < 0.01). At the same time, it could decrease mortality rate, comparing with Dopamine and NS the difference was significant (P < 0.05, P < 0.01); and it could also inhibit the formation of lipid peroxides (LPO). The contents of LPO in heart, liver, kidney of shock rabbit were obviously lower than that of Dopamine and NS groups (P < 0.05, P < 0.01). The electron microscopy indicated that the drug could relieve the injury of mitochondria and lysosome in the tissues of heart, liver and kidney and protect the cellular ultrastructure of cardinal viscera. This study suggests that the JTII had good efficacy in treating the shock rabbit caused by SMAO method.

Animals↗
PubMed1994

[Immunologic suppressor factors in sera of patients with ovarian cancer].

The suppressive activity of immunologic suppressor factors (ISF) in the sera of 34 patients with ovarian cancer was investigated by using the lymphocyte proliferation and inhibition test. It was found that the sera of the preoperative patients could significantly suppress PHA-induced lymphocyte response, and that the suppression was dose-dependent. When the sera were diluted to 1 : 4,000, the suppressive activity could still be demonstrated. We also observed the suppressive activities in the sera of patients with cervical cancer, endometrial cancer, gastric cancer and lung cancer, and compared them with ovarian cancer patients. The observation showed that the suppressive activity in the sera of preoperative ovarian cancer patients was higher than that in the sera of gastric cancer or lung cancer patients. These results suggested that ISF played an important role in the development of ovarian cancer.

Adult↗
PubMed1993

[Biological basis of thermochemotherapy].

Interactive effects of combined treatment with hyperthermia and chemotherapeutic agents or chemical substances were interpreted in the experimental aspects of medical sciences. It was also interpreted how a physiological circumferential conditions in vivo influenced on thermosensitivities of cells, tissues or individuals. Among the physiological conditions, hypoxia and insufficient nutrition apparently enhance thermosensitivity while reduce radiosensitivity. Interactive effects in combined treatments with hyperthermia and alkylating agents varies among the alkylating agent adopted. DNA strand scission by alkylating agent is increased and repair of the DNA damage is suppressed in combination with hyperthermia. Almost all the antimetabolites and botanic alkaloids are reported to show no appreciable interactive effect in combination with hyperthermia. However, a sort of derivatives of mitotic toxins interacts with hyperthermia (unpublished data). Effects of anticancer antibiotics vary due to the variety of the mechanism of action of the antibiotics. Therefore, interactive effects of these antibiotics with hyperthermia also vary among the antibiotics. Most marked interaction with hyperthermia was shown in Mitomycin C, while the cell killing effect of Actinomycin D itself was reduced reportedly by the combined hyperthermia. Further development in thermophysiology may perform an extent of elevation in human whole body temperature. It has been considered internal heating may be more efficient than external heating for the hyperthermia alone. In the other hand, local heating can chemosensitize within the localized heated area where the blood concentration of anticancer drug is even, although variety of intervention could be devised to localize anticancer drug distribution. Variety of heating modalities and the apparatus would be developed which contribute for further interdisciplinary oncotherapy in near future.

Antineoplastic Agents↗
PubMed1991

Range perception through apparent image speed in freely flying honeybees.

When negotiating a narrow gap, honeybees tend to fly through the middle of the gap, balancing the distances to the boundary on either side. To investigate the basis of this "centering response," bees were trained to fly through a tunnel on their way to a feeding site and back, while their flight trajectories were filmed from above. The wall on either side carried a visual pattern. When the patterns were stationary vertical gratings, bees tended to fly through the middle of the tunnel, i.e. along its longitudinal axis. However, when one of the gratings was in motion, bees flying in the same direction as the moving grating tended to fly closer to it, while bees flying in the opposite direction tended to fly closer to the stationary grating. This demonstrates, directly and unequivocally, that flying bees estimate the distances of surfaces in terms of the apparent motion of their images. A series of further experiments revealed that the distance to the gratings is gauged in terms of their apparent angular speeds, and that the visual system of the bee is capable of measuring angular speed largely independently of the spatial period, intensity profile, or contrast of the grating. Thus, the motion-sensitive mechanisms mediating range perception appear to be qualitatively different from those that mediate the well-known optomotor response in insects, or those involved in motion detection and ocular tracking in man.

Animals↗
PubMed1991

[Selenium concentrations in serum, hair and tumor tissue from patients with ovarian tumors].

Selenium (Se) concentration was determined in 150 samples of serum, 135 samples of hair and 96 samples of ovarian tissue from patients with malignant or benign ovarian tumors and normal subjects. The serum Se level in patients with malignant ovarian tumors was significantly lower than that in patients with benign ovarian tumors and normal subjects. No difference of Se concentrations of hair among different groups was observed. Se level in malignant ovarian tumor tissue was significantly higher than that in benign ovarian tumor tissue and normal ovarian tissue. The low serum Se level in patients with malignant ovarian tumors was probably the result of protective migration of Se from blood to the cancer tissue.

Adult↗
PubMed1990

Visual tracking of moving targets by freely flying honeybees.

The ability of freely-flying honeybees to track moving targets was examined by training them to collect a reward on a target, and then videotaping their approach to the target while it was in motion. Training experiments were carried out with several groups of bees, using various colors for the target and the background. Computer-aided frame-by-frame analysis of video recordings was used to plot the instantaneous positions of the target, as well as the position and orientation of the approaching bee in three dimensions. The results show that bees are perfectly capable of tracking moving targets and landing on them. When the distance of the target is greater than 15 cm, approaching bees correct for angular deviations of the target from the midline, both in the horizontal and in the vertical plane. In either plane, the input variables that are important to the tracking system seem to be (1) the angular bearing of the target with respect to the midline, and (2) the angular velocity of the target with respect to the eye. The tracking control system tends to orient the bee such that the target is located frontally, at an angle of ca. 35 deg below the bee's long axis. The chromatic properties of tracking behavior were investigated by employing combinations of colors for the target and background such that the boundary between the target and the background presented a contrast that was visible either only to the green-sensitive receptors of the bee's eye, or only to the blue-sensitive receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Role of pulmonary innervation in canine in situ lung-perfusion preparation: a new model of neurogenic pulmonary oedema.

1. In situ canine lungs were perfused in the presence or absence of the nerves which coursed to the heart and lungs (the cardiopulmonary nerves, CPN). 2. A right heart-bypassed preparation was made first, so that the respiratory and circulatory conditions could be controlled beforehand. It was then switched to a lung-perfusion preparation, in which the lungs receive all influences of sudden cessation of the brain and systemic circulations solely via the CPN. Hydrostatic mechanisms causing pulmonary oedema were excluded by adjusting the pulmonary arterial pressure under 300 mmH2O (less than 24 mmHg). 3. Accumulation of extravascular lung water and the rate of reservoir blood loss were significantly lower in the CPN-severed group than in the CPN-intact group. 4. After perfusion of 90 min, total loss of reservoir blood was correlated significantly with extravascular water content in lungs. The former was larger than the latter. 5. Elevation of left atrial pressure caused an increase in the rate of reservoir blood loss. When the CPN was severed, the relation between these two parameters was shifted to the right. 6. These findings indicate a CPN-mediated genesis of permeability pulmonary oedema.

Animals↗