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Biomedical subjects

D Zhou

Publications and source records attributed to D Zhou.

At least 325 records · Page 18Linked to original sources
PubMed1992

[Effect of poly-saccharide sulphate on thixotropic properties of whole blood in patients with cerebral thrombosis].

Using Low shear 30 rheometer, we measured the thixotropic parameters of blood from 30 patients suffering from cerebral thrombosis. The result showed that the yield stress (tau 0), non-Newtonian contribution of viscosity (eta s-mu) and viscosity of plasma (eta p) were significantly higher than those in the control group. Those patients were randomly divided into two groups. Each group included 15 patients. The patients in group 1 and group 2 were treated with poly-saccharide sulphate (PSS) and DX40 respectively by intravenous drip for 14 days. The results showed that tau 0, A, (eta s-mu) were significant decreased in group 1 after treatment, but no significantly change in the thixotropic parameters was found in group 2 after treatment. The total curative rate in group 1 was higher than that in group 2. These results suggest that the patients with cerebral thrombosis had evidently increased degree of RBC aggregation. PSS could decrease the aggregation of RBC more significantly than DX40 did. It was probably one of the reasons why the therapeutic effect of PSS on cerebral thrombosis was better than that of DX40.

Aged↗
PubMed1991

Early steps of isoprenoid biosynthesis in Escherichia coli.

The incorporation of 2H- and 13C-labelled precursors into ubiquinone-8 (Uq-8) by strains of Escherichia coli was measured in order to define the pathway for the early steps in the biosynthesis of isoprenoids in these eubacteria. Cells grown with DL-[methyl-2H6]valine were found to label both the alpha-oxoisovaleric ('alpha-ketoisovaleric') acid alpha-oxoisohexanoic ('alpha-ketoisocaproic') acid, but not the Uq-8. Since these acids are required for the biosynthesis of isoprenoids by the acetolactate pathway, the operation of this pathway in the biosynthesis of Uq-8 is excluded. Cells grown with [1,2-13C2]acetate and non-labelled glucose readily incorporated 13C2 units into fatty acids, but failed to incorporate any label into the Uq-8. Cells grown with [U-13C6]glucose and non-labelled acetate, however, were found to label both the fatty acids and the Uq-8. Oxidative cleavage with periodate/permanganate of the Uq-8 isolated from cells grown with U-13C6-labelled glucose produced laevulinic acid, which was shown to be derived from two C2 units and one C1 unit of the labelled glucose by mass-spectral analysis of the 4,5-dihydro-6-methyl-2-phenylpyridazin-3(2H)-one derivative. The results of this work indicate that the C-2 and C-3 carbon unit of pyruvate, not acetyl-CoA, is the precursor to isopentenyl pyrophosphate (IPP) in these cells; however, the labelling pattern observed is consistent with the established acetoacetate pathway of isoprenoid biosynthesis. These data, coupled with the observed lack of inhibition of the growth of E. coli by mevinolin, a specific inhibitor of 3-hydroxy-3-methylglutaryl-CoA, can be best rationalized by the biosynthesis of IPP occurring in E. coli through a series of bound intermediates.

Acetates↗
PubMed1991

Expression of anionic glutathione S transferase (GST pi) gene in carcinomas of the uterine cervix and in normal cervices.

The aim of the present study was to analyse in invasive carcinomas of the uterine cervix, the anionic glutathione S transferase (GST pi) gene, possibly implicated in the drug resistance of human cancers. Total RNA preparations obtained from invasive cervical cancers (106 specimens), carcinomas in situ (CIS) (three specimens) and normal cervical epitheliums (24 specimens) were analysed by Northern and slot blot hybridisation. A 0.7 kb GST pi transcript band was detected in all the cervical specimens. GST pi mRNA levels were lower in normal cervix (mean: 0.7 +/- 0.1 arbitrary units) than in invasive carcinomas (mean: 2.5 +/- 1.5 units) (Student test P less than 10(-4)). However no significant difference was observed between invasive cancers of advanced stages (III and IV) and those of early stages (I and II). The presence of human papillomavirus in cancers and in normal cervices did not influence significantly the GST pi mRNA level. Neither amplification nor gross rearrangement of GST pi gene could be observed after Southern blot analysis of genomic DNA. In conclusion, our data indicate that the presence of high levels of GST pi transcripts in invasive cancers may be a consequence of the multiple biochemical changes which accompany cervical carcinogenesis.

Cervix Uteri↗
PubMed1991

Pathologic concentrations of interleukin 6 inhibit T cell responses via induction of activation of TGF-beta.

Interleukin 6 levels are increased in a variety of clinical conditions including bacterial and viral infections, HIV infection, autoimmune diseases, certain neoplasias, and traumatic injury. In general, all these conditions are characterized by suppression of one or more manifestations of the immune response. Concentrations of IL 6 comparable to those found in the sera of immunosuppressed, thermally injured patients selectively inhibit T cell proliferative responses. This suppression is independent of IL 2-mediated responses, is dependent on macrophage activity, and is reversed by antisera specific for transforming growth factor-beta (TGF-beta).

Animals↗
PubMed1991

Vestibular and cerebellar modulation of expiratory motor activities in the cat.

1. The purpose of our investigation was to evaluate the hypothesis that components of the vestibular and cerebellar systems regulate efferent respiratory-modulated activities of cranial and spinal nerves. The hypothesis was based upon the observation that spinal neural activities during expiration are greatly altered subsequent to a change in posture. 2. In decerebrate and paralysed cats, efferent activities were recorded from the central cut ends of the phrenic nerve, intercostal nerve, branch of the intercostal nerve innervating the triangularis sterni, cranial iliohypogastric (abdominal) nerve and recurrent laryngeal nerve. 3. Animals were artificially ventilated. Those with intact vagi were ventilated by a servo-respirator which produced changes in lung volume in parallel with alterations in integrated activity of the phrenic nerve. Animals with bilateral vagotomy were ventilated with a standard respirator. 4. Aspiration of the entire cerebellar cortex did not produce alterations in levels of neural activities; the respiratory frequency was increased modestly. Following ablation of the ventrolateral portion of corpus medullare and cerebellar peduncles, expiratory activities of spinal nerves were completely eliminated whereas inspiratory activities were not greatly altered. Results were similar in animals having either intact or sectioned vagi. 5. Electrical stimulation or chemical stimulation by glutamate of regions of the ventrolateral cerebellum produced little change in respiratory neural activities except when these stimulations were within the infracerebellar nucleus. Stimulations in this nucleus caused pronounced increases in expiratory activities of spinal nerves. Neither inspiratory activities of spinal nerves nor inspiratory or expiratory activities of the recurrent laryngeal nerve were altered. Studies in animals having intact or sectioned vagi yielded similar results. 6. Bilateral lesions of neurons in the infracerebellar nucleus by injections of kainic acid in animals having intact or sectioned vagi caused an irreversible loss of expiratory activities of spinal nerves with neither inspiratory spinal activities nor inspiratory and expiratory laryngeal activities being altered. Similar findings were obtained following unilateral ablation of the infracerebellar nucleus in vagotomized cats. However, in cats with intact vagi, unilateral ablation of the infracerebellar nucleus produced only transient changes in either inspiratory or expiratory neural activities.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1991

Transsulfuration in archaebacteria.

The transfer of sulfur from methionine to cysteine in the archaebacteria Sulfolobus acidocaldarius and Halobacterium marismortui was studied by feeding 34S-labeled methionine to cells and measuring the incorporation of 34S into protein-bound cellular cysteine and methionine by mass spectrometry. It was found that, as are eucaryotes, both of these archaebacteria were able to convert the sulfur of methionine to cysteine.

Archaea↗
PubMed1991

Differing activities of medullary respiratory neurons in eupnea and gasping.

Our purpose was to compare further eupneic ventilatory activity with that of gasping. Decerebrate, paralyzed, and ventilated cats were used; the vagi were sectioned within the thorax caudal to the laryngeal branches. Activities of the phrenic nerve and medullary respiratory neurons were recorded. Antidromic invasion was used to define bulbospinal, laryngeal, or not antidromically activated units. The ventilatory pattern was reversibly altered to gasping by exposure to 1% carbon monoxide in air. In eupnea, activities of inspiratory neurons commenced at various times during inspiration, and for most the discharge frequency gradually increased. In gasping, the peak discharge frequency of inspiratory neurons was unaltered. However, all commenced activities at the start of the phrenic burst and reached peak discharge almost immediately. The discharge frequencies of all groups of expiratory neurons fell in gasping, with many neurons ceasing activity entirely. These data are consistent with the hypothesis that brain stem mechanisms controlling eupnea and gasping differ fundamentally.

Animals↗
PubMed1991

Rostral pontile mechanisms regulate durations of expiratory phases.

Neural expiration can be divided into two phases. Phase I corresponds to the period of laryngeal adduction, whereas many spinal nerves reach peak discharge in phase II. The present studies evaluated the hypothesis that rostral pontile mechanisms contribute to determining the time of onset of spinal motoneuronal activities in phase II. In decerebrate and paralyzed cats, efferent activities were recorded from the phrenic nerve and from single fibers of the branch of the intercostal nerve innervating the triangularis sterni muscle. These activities were recorded in eupnea and apneusis; the latter was produced by cooling the rostral pons by a fork thermode. In eupnea, there was a delay between the rapid decline of phrenic discharge from peak levels and the commencement of activities of motoneurons of the triangularis sterni. This delay was significantly reduced in apneusis. Peak discharge frequencies of triangularis sterni motoneurons were the same in eupnea and apneusis. We conclude that rostral pontile mechanisms contribute significantly to defining the phases of neural expiration.

Animals↗
PubMed1991

[Comparison of the effects of 4 psychiatric treatments on rat brain beta 5HT2 receptors].

Four psychiatric treatments, such as electro-convulsive treatment (ECT), insulin coma, electroacupuncture (EA) and antidepressants were given to rats chronically, and the brain cortex beta and serotonin2 receptors were measured. Comparing with their control groups we found that chronic ECT, insulin coma and EA have similar effect to down-regulate the specific coma and EA have receptor, but almost no effect on serotonin2 receptor. Antidepressants have various effects on brain monoamine receptors. The major effects of desipramine and imipramine were down-regulate B receptor, while of amitriptyline was down-regulate 5HT2 receptor. Our data suggested that different psychiatric treatment might effort their therapeutic effects mediated by different monoamine function in CNS.

Acupuncture Therapy↗
PubMed1991

[Research on thixotropic properties of whole blood in patients with ischemic stroke and its high risk].

So far, few papers on alteration of thixotropic properties of blood from patients with cerebrovascular disease have been found. We measured the thixotropic parameters of blood from 92 patients suffering from cerebrovascular diseases. These patients were divided into five groups. Group I consisted of 14 male patients with cerebral arteriosclerosis (CA) (aged 61.7 +/- 8.2 years) and Group II, 12 male patients with transient cerebral ischemic attack (TIA) (64.4 +/- 7.8 years). All of patients in groups III (22 male old patients, 66.6 +/- 5.1 years), IV (24 male middle-aged patients 53.7 +/- 2.8 years), and V (20 female patients 58.4 +/- 13.8 years) were suffering from cerebral thrombosis. These 92 patients and 92 selected healthy subjects were pair matched in sex and age. Using paired t-test, we compared their thixotropic parameters. The results showed that the yield stress (tau 0), the equilibrium value of the structural parameter (A), the apparent viscosity at 2.37 s-1 (eta s), and non-Newtonian contribution of viscosity (eta s-mu) in groups I, II and III were significantly higher than those in the corresponding control groups. The values of tau 0, A, eta s, (eta s-mu) and eta p of blood in group V were higher than those in the control group; only the values of tau 0, eta p, (eta s-mu) of blood in group IV were higher than those in the control group. No significant difference in the thixotropic parameters was noted among groups I, II and III. The results suggest that the patients with cerebrovascular diseases had evidently increased number and degree of RBC aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

[Study on ursodeoxycholic acid biotransformation by three strains of clostridia].

Using the improved TLC procedure, we measured the conversion rates of ursodeoxycholic acid(UDCA) from chenodeoxycholic acid (CDCA) by 3 strains of clostridia--C. perfringens HS-10, C. butyricum DL-20 and LQ-29 isolated. The orthogonal test was used to determine the optical conditions of biotransformation for HS-10. It was found that the conversion rate of UDCA by HS-10 was over 80% during 6-48 h in RCM medium containing 0.2 mmol/L CDCA. The UDCA conversion rates were still over 70% when the CDCA concentrations were as high as 0.8-1.0 mmol/L. In addition, the WW-BCP (Waste water from bean curd production) without any supplemental nutrients was preliminarily proved to be a potential inexpensive conversion medium.

Biotransformation↗
PubMed1991

[Long-term pathological findings of cerebral arteriovenous malformation after embolization].

Cerebral arteriovenous malformation was resected after embolization with Aron alpha and ZT plastic in 2 cases. Pathological examination in one patient revealed intravascular residual foreign-body giant-cell reaction and slight chronic inflammation in the adjacent parenchyma of the brain tissue 1.5 years after embolization. The other 1 patient was treated with embolization 4.5 years ago. No pathological changes were found either in the vessels or in the brain tissue. It is indicated that chronic inflammation after embolization with cyanoacrylate disapproved several years later.

Adult↗
PubMed1990

Expression of multidrug-resistance (MDR1) gene in normal epithelia and in invasive carcinomas of the uterine cervix.

Total RNA from 92 invasive cervical cancers was analyzed for the presence of multidrug-resistance (MDR1) gene (also known as PGY1) transcripts. A 4.5-kilobase MDR1 transcript band was detected in 40 (43%) of 92 invasive cervical carcinomas and in 15 (68%) of 22 normal cervices. MDR1 levels were low [mean, 2.5 arbitrary units (U)] except in one liver metastasis (50 U) treated with a drug regimen including vincristine. Of eight carcinomas treated by radiotherapy and/or chemotherapy, seven (88%) exhibited MDR1 transcripts as compared with 24 (35%) of 69 untreated carcinomas (Fisher's exact test; P = .01). In conclusion, our data suggest that the MDR1 gene plays a role in drug resistance of certain cervical cancers, but also that other mechanisms may be involved.

Adenocarcinoma↗
PubMed1990

Discharge of vagal pulmonary receptors differentially alters neural activities during various stages of expiration in the cat.

1. The purpose was to evaluate the hypothesis that neural expiration is composed of two phases: I, a post inspiratory period; and II, the period at which expiratory activities of spinal nerves reach peak values. We hypothesized that the discharge of pulmonary stretch receptors might differentially alter neural activities during these two phases. 2. Activities of the phrenic nerve, intercostal nerve and nerves innervating the thyroarytenoid muscle of the larynx and triangularis sterni muscle of the chest wall were recorded in decerebrate and paralysed cats. 3. The experimental animals were ventilated with a servo-respirator which produced changes in tracheal pressure, and lung volume, in parallel with alterations in integrated activity of the phrenic nerve. 4. In order to assess the influence of the discharge of slowly adapting pulmonary stretch receptors upon neural activities during expiration, lung volume was held at end-expiratory or end-inspiratory levels for individual respiratory cycles. 5. When pulmonary inflation was prevented, phrenic activity increased, as did activity of the thyroarytenoid nerve during early expiration. In contrast, activities of the triangularis sterni and intercostal nerves during mid- to late expiration declined. 6. Holding the lungs at end-inspiratory levels caused a reduction of thyroarytenoid activity and increases in peak triangularis sterni and intercostal activities. Neural expiration typically continued as long as the lungs were maintained at the end-inspiratory level. 7. Responses were qualitatively similar in hypocapnia, normocapnia and hypercapnia, but the magnitude of changes in neural activities was typically augmented with elevations in end-tidal fractional concentrations of CO2. 8. We conclude that the discharge of slowly adapting pulmonary stretch receptors inhibits neural activities during early expiration and augments activities during mid-to late expiration. Hence, our data support the concept that neural expiration is composed of two stages in which neural activities may be differentially controlled.

Animals↗