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Biomedical subjects

D Zhou

Publications and source records attributed to D Zhou.

At least 343 records · Page 19Linked to original sources
PubMed1990

[c-myc and c-Ha-ras proto-oncogenes in cervical cancer: prognostic value].

The biological behaviour of invasive carcinoma of the uterine cervix is not always predictable. It is therefore important to establish new biological markers which could be useful in determining a more reliable prognosis. We have analyzed the c-Ha-ras and c-myc proto-oncogenes in a large series (154 cases) of cervical cancers at various clinical stages. Alterations of c-Ha-ras (deletion, mutation) and c-myc (amplification) were frequently observed in cervical cancers and were shown to be associated with tumor progression. Furthermore, c-myc overexpression, when detected in early cervical cancers, provides a means of identifying patients at high risk of early recurrence.

Biomarkers, Tumor↗
PubMed1989

Tissue-specific expression of c-Ha-ras in premalignant gastrointestinal mucosae.

The molecular mechanisms underlying premalignant gastrointestinal diseases, such as ulcerative colitis and Barrett's esophagus, remain unknown. For this reason, the expression of the protooncogene c-Ha-ras was studied in ulcerative colitis and Barrett's esophagus. Total cellular RNA was extracted from different regions of the gastrointestinal tract in these two diseases. Expression of c-Ha-ras was greater in proximal than in distal colon and undetectable in Barrett's esophagus. These regional differences in expression were not seen with the control gene beta-actin or with the protooncogenes c-myc and p53. In order to evaluate structural factors contributing to expression, amplification and methylation of c-Ha-ras DNA were studied in these tissues by Southern and slot blotting. No amplification of c-Ha-ras or six other protooncogenes was detected. These data suggest tissue-specific regulation of c-Ha-ras expression in the gastrointestinal tract in certain premalignant disease states.

Adenomatous Polyposis Coli↗
PubMed1989

Activities of pulmonary stretch receptors during ventilatory cycles without lung inflation.

When lung inflation is temporarily withheld in paralyzed, ventilated cats with intact vagi, the activities of inspiratory motor nerves are greater during the second cycle without inflation than during the first. This response is not easily attributable to increasing drive from chemoreceptors as it is abolished by vagotomy. We examined the hypothesis that the increasing inspiratory activity is the result of decreasing inhibitory feedback from pulmonary stretch receptors (PSRs). Decerebrate, paralyzed cats were ventilated by a servo-respirator in accordance with their own phrenic nerve activity. Afferent activities from individual PSRs were recorded from a few cut fibers of one vagus nerve; the vagi were otherwise intact. When lung inflation was withheld, phrenic and hypoglossal nerve activities and the durations of inspiration and expiration all increased and were significantly greater during the second cycle without inflation than during the first. The frequency of PSR discharge was also greater during the second cycle and thus did not account for the responses recorded from the motor nerves. We conclude that the latter responses probably reflect neural processes within the brain stem, involving a persistent inhibitory influence from lung inflation, which outlasts the inflation itself.

Animals↗
PubMed1989

Functions of the retrofacial nucleus in chemosensitivity and ventilatory neurogenesis.

The hypothesis was evaluated that neurons within the retrofacial nucleus of medulla integrate afferent stimuli from the central chemoreceptors. In decerebrate, vagotomized, paralyzed and ventilated cats, activity of the phrenic nerve was monitored. Peak integrated phrenic activity increased in hypercapnia; the frequency of phrenic bursts typically declined slightly. The retrofacial nucleus was ablated by radio-frequency lesions or neurons within this nucleus were destroyed by microinjections of kainic acid. Results were similar following lesions or injections. Following unilateral ablations, peak phrenic activity was greatly reduced at normocapnia and hypercapnia; the frequency of phrenic bursts typically rose. Both frequency and peak phrenic activity fell further after the contralateral destruction with a cessation of all phasic phrenic discharge being observed in most animals. Injections of kainic acid in regions rostral, caudal or medial to the retrofacial nucleus produced no consistent changes in phrenic activity. We conclude that neuronal activities in the region of the retrofacial nucleus are important both in the integration of stimuli from the central chemoreceptors and in defining the discharge patterns of respiratory neurons.

Animals↗
PubMed1989

Differing control of neural activities during various portions of expiration in the cat.

1. Activities of the phrenic nerve, intercostal nerve and nerves innervating the thyroarytenoid (TA) muscle of the larynx and triangularis sterni (TS) muscle of the chest wall were recorded in decerebrate, vagotomized, paralysed and ventilated cats. 2. Neural inspiration was defined by the phase of phrenic activity. Neural expiration was divided into two phases with phase I corresponding to the duration of TA activity and phase II to TS activity: intercostal nerves discharged across both phases. 3. Phrenic activity was terminated prematurely by electrical stimulation of the superior laryngeal nerve or of the dorsolateral region of the rostral pons. Following stimulation, neural activities during phase I of expiration rose and those during phase II fell in most animals. 4. Stimulation of the superior laryngeal nerve during phase I caused augmentations of both TA and TS activity. At the termination of stimulation, a phase of TA discharge was recorded followed by a phase of TS activity. The durations of these post-stimulation phases of TA and TS activities approximated those of cycles without stimulation. 5. Stimulation of the superior laryngeal nerve during phase II caused a resetting of neural expiration. Following stimulation, phases of TA and TS activity were recorded which had durations approximating those of cycles without stimulation. 6. The current required to induce a premature onset of phrenic activity by stimulation of the dorsolateral region of the rostral pons fell dramatically with the change from phase I to phase II of expiration. 7. We conclude that the control of neural activities differs markedly between phase I and phase II of expiration. The data support the hypothesis that post-inspiratory medullary respiratory neurones play a fundamental role in the definition of the ventilatory cycle.

Animals↗
PubMed1989

Biosynthesis of caldariellaquinone in Sulfolobus spp.

The biosynthesis of caldariellaquionone (CQ) was studied in species of Sulfolobus by measuring the incorporation of stable isotopically labeled tyrosines into CQ. By feeding a series of tyrosines labeled with deuterium or 13C and then measuring the extent and position at which label was incorporated into CQ by mass spectrometry, it was shown that more than 95% of the label was incorporated into the benzo[b]thiophen-4,7-quinone moiety of CQ. From the labeling experiments, it is concluded that the benzo[b]thiophen-4,7-quinone is derived as an intact unit from all of the carbons of tyrosine except C-1.

Carbon Isotopes↗
PubMed1989

Expiratory neural activities in gasping.

The purpose was to characterize expiratory-related neural activities in eupnea and gasping. In decerebrate and vagotomized cats, activities were recorded from the phrenic nerve, spinal intercostal and abdominal nerves, and recurrent laryngeal nerve and its branches. Neural inspiration was defined by phrenic discharge. The spinal and laryngeal nerves discharged in inspiration, expiration, or during both phases. Gasping was induced by freezing the brain stem at the pontomedullary junction, exposure to asphyxia or anoxia, or ligation of the basilar artery and its branches. In gasping, peak phrenic activity typically increased as did inspiratory-related activities of laryngeal and spinal nerves. Expiratory activities were greatly reduced in gasping, with some activities being completely eliminated. Reductions of expiratory activity were more prominent for spinal than laryngeal nerves. Similar results were obtained in cats having intact vagi that were ventilated with a servo-respirator so that lung inflation paralleled phrenic activity. The concept that gasping differs fundamentally form other ventilatory patterns is discussed.

Animals↗
PubMed1989

Respiratory activities of intralaryngeal branches of the recurrent laryngeal nerve.

To distinguish experimentally between motor nerve activity destined for vocal cord abductor muscles and that bound for muscles that adduct the cords, we recorded efferent activities of intralaryngeal branches of the recurrent laryngeal nerve (RLN) in decerebrate, vagotomized, paralyzed, ventilated cats. Activities of the whole RLN and phrenic nerve were also recorded. Nerve activities were assessed at several steady-state end-tidal O2 and CO2 concentrations. The nerve to the thyroarytenoid (TA) muscle, a vocal cord adductor, was only slightly active under base-line (normocapnic, hyperoxic) conditions but in most cats developed strong activity during expiration in hypocapnia or hypoxia. In severe hypocapnia, phasic expiratory TA activity persisted even during phrenic apnea, indicating continuing activity of the respiratory rhythm generator. The nerve to the posterior cricoarytenoid (PCA) muscle, the vocal cord abductor, was always active in inspiration but often showed expiratory activity as well. This expiratory activity was usually enhanced by hypercapnia and often inhibited by hypoxia. The results are consistent with previous electromyographic findings and emphasize the importance of distinguishing abductor from adductor activity in studies of laryngeal control.

Animals↗
PubMed1989

Influence of lung volume on activities of branches of the recurrent laryngeal nerve.

To investigate the influence of inspiratory lung inflation on the respiratory activities of laryngeal motor nerves, vagally intact decerebrate paralyzed cats were ventilated by a servorespirator in accordance with their own phrenic nerve activity. Records were made of the activities of the phrenic nerve, the superior laryngeal nerve (SLN), the recurrent laryngeal nerve (RLN), and the intralaryngeal branches of the RLN serving the thyroarytenoid (TA) and posterior cricoarytenoid (PCA) muscles. Neural activities were assessed in the steady state at different end-tidal O2 and CO2 concentrations. Transient responses to withholding inspiratory lung inflation and to preventing expiratory lung emptying were also studied. Hypercapnia and hypoxia increased the inspiratory activities of the phrenic nerve, SLN, RLN, and its PCA branch. TA inspiratory activity was not changed. Expiratory activities of RLN, PCA, and TA were all increased in hypoxia. When lung inflation was withheld, neural inspiratory duration and the inspiratory activities of all nerves increased. The subsequent period of neural expiration was marked by an exaggerated burst of activity by the TA branch of the RLN. TA expiratory activity was also sharply increased after inspiratory efforts that were reflexly delayed by the prevention of lung emptying. TA activity in expiration was enhanced after vagotomy and was usually more prominent than when lung inflation was withheld before vagal section. The results demonstrate the importance and complexity of the influence of vagal afferents on laryngeal motor activity.

Afferent Pathways↗
PubMed1989

Characterization of expiratory intercostal activity to triangularis sterni in cats.

Our purpose was to characterize activity of the intercostal nerve branch innervating the triangularis sterni muscle and the motoneuronal activities comprising this nerve discharge. In decerebrate, vagotomized, paralyzed, and ventilated cats, phasic triangularis sterni neural activity was evident in normocapnia. In most cats, activity did not commence until midexpiration. Activity then rose progressively to terminate at end expiration. Peak neural activities increased in parallel with phrenic activity in hypercapnia and fell in hypocapnia. The progressive increase in triangularis sterni neural activity within each respiratory cycle resulted from recruitment of motoneuronal activities throughout expiration. Once recruited, many motoneurons had a decrementing or constant discharge frequency. In hypercapnia, motoneuronal discharge frequencies increased, and additional activities were recruited. The number of active motoneurons and their discharge frequencies fell in hypocapnia. A similar pattern of motoneuronal activities and responses to stimuli was observed in cats with intact vagi. Factors are considered that may underlie the recruitment pattern of triangularis sterni motoneuronal activities and the inhibition of these in early expiration.

Animals↗
PubMed1989

[Immunologic changes in serum CuZn-containing superoxide dismutase in patients with lung cancer].

Serum immunologic changed CuZn-containing superoxide dismutase (CuZn-SOD) level was determined in 45 patients with lung cancer and the results were compared with those in 22 normal persons and 19 cases with benign pulmonary diseases. The results were as follows: x +/- Sx of CuZn-SOD in the lung cancer group was 16.11 +/- 0.78 ng/ml, that in the benign pulmonary disease group was 9.51 +/- 0.61 ng/ml and that in the normal adults group was 7.22 +/- 0.79 ng/ml. The mean of the activity of serum immunologic changed CuZn-SOD in patients with lung cancer was significantly high than that in the other two groups. (P less than 0.001). If a serum immunologic changed CuZn-SOD level of 11.98 ng/ml and over is considered as Positive, the positive rate will be 80%, 11%, and 4.5% in the three groups respectively. In the light of the above findings, we suggest that determination of the activity of serum immunologic changed CuZn-SOD is helpful in the diagnosis of lung cancer.

Adenocarcinoma↗
PubMed1989

[Research on thixotropic parameters of whole blood from Chinese adult subjects].

This study measured the thixotropic parameters of whole blood from 314 healthy subjects (154 women, 160 men) with our modified method by Low Shear-30 Rheometer according to Huang's equation. We suggested the range of normal values of thixotropic parameters from man and woman group. The results demonstrated that no significant differences existed in the plasma viscosity (eta p) and fibrinogen between man and woman group. Man group had significantly higher values than those in woman group in hematocrit (HCT), yield stress (tau 0), Newtonian contribution of viscosity (mu), non-Newtonion contribution of viscosity (eta s-mu), apparent viscosity at 2.37s-1 (eta s), the equilibrium value of the structural parameter (A) and apparent kinetic rate constant of rouleaux breakdown (ARC). The man and woman groups could be separately divided into five subgroups on the basis of age. All parameters were compared with one another and treated statistically. We found that the levels of fibrinogen and eta p had an increasing trend with aging. In the old subgroup (greater than or equal to 60 years) of man and woman, HCT, tau 0, mu, eta s, (eta s-mu) and A had significantly lower values than those in young and middle age subgroups. However, it was very interesting that there were differences of ARC versus age between the man and woman groups, i.e., ARC in the man subgroup 3, 4 had lower values and in the woman subgroup 2, 3, 4 had higher values than their respective older subgroups did.

Adolescent↗
PubMed1989

Direct sequencing analysis of exon 1 of the c-K-ras gene shows a low frequency of mutations in human pancreatic adenocarcinomas.

We have applied direct dideoxy sequencing of DNA fragments amplified in vitro by the polymerase chain reaction to the detection of mutations in exon 1 of the c-K-ras gene in human pancreatic adenocarcinomas. Four fresh frozen primary tumors, one metastatic tumor, and twelve formalin-fixed paraffin embedded tumors were analysed. Only three cases showed a possible mutation in codon 12 in a small population of cells, in contrast to the high frequency reported for this alteration with the RNAase A protection assay and allele-specific oligoxynucleotide hybridization. No major difference in sensitivity was found between DNA sequence analysis, and the latter method. Our results suggest that if c-K-ras mutations are indeed present in pancreatic adenocarcinomas at the high frequency reported by others, they must be confined to a small fraction of the cell population to escape detection by direct sequencing. Such a phenomenon would have implications for c-K-ras mutations in the pathogenesis of pancreatic adenocarcinomas.

Adenocarcinoma↗