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Biomedical subjects

L Ling

Publications and source records attributed to L Ling.

At least 19 recordsLinked to original sources
PubMed1992

Emergency medicine.

Explore the source record for details and available documents.

Cardiopulmonary Resuscitation↗
PubMed1992

Effects of intravenous bicuculline and strychnine on inspiratory inhibitory responses in the cat.

Single shock stimulation of the superior laryngeal nerve (SLN), intercostal nerve (ICN), phrenic nerve (PN) or within the medullary respiratory groups (DRG-VRG) produces a transient, short-latency attenuation of inspiratory motor activity. Trains of stimuli delivered to SLN and ICN cause premature termination of inspiration. This study examined involvement of glycine and GABAA receptors in these reflex inhibitions. Experiments were conducted in decerebrate, vagotomized, and paralyzed cats. Control responses of left PN activity to threshold single shock stimulation of SLN, PN, ICN and the DRG-VRG were recorded and the thresholds for SLN- and ICN-evoked inspiratory termination were determined. Five min after intravenous injection of bicuculline (1 mg/kg) or strychnine (50 micrograms/kg), the responses to stimulation were again recorded. This procedure was reiterated until the cumulative dose elicited marked convulsions. Neither drug affected the inspiratory terminating reflexes. Systemic bicuculline had no effect on transient inspiratory inhibition. However strychnine prolonged the onset latency and the duration of all four inhibitory responses. Since the degree of transient inhibition was not lessened (only delayed), it appears that these inspiratory inhibitory reflexes do not rely exclusively on actions of glycine or GABAA receptors.

Animals↗
PubMed1992

Discharge patterns of levator palpebrae superioris motoneurons during vertical lid and eye movements in the monkey.

1. We recorded single-unit activity in the caudal central nucleus (CCN) of the oculomotor complex in monkeys trained to make vertical saccadic, smooth-pursuit, and fixation eye movements. We confirmed that our recordings were from motoneurons innervating the upper lid, because small lesions placed at the sites of responsive units were recovered among neurons labeled by horseradish peroxidase (HRP) injections into the levator palpebrae superioris muscle. 2. For fixations above a threshold lid position, levator motoneurons discharged at a steady rate, which increased linearly with upward lid position. The average position sensitivity during fixation was 2.9 spikes/s per deg, and the average lid motoneuron was recruited into steady firing when the eye was looking 10 degrees down. 3. During upward saccades, levator motoneurons discharged a burst of spikes that began, on average, 7.3 ms before the lid movement if the saccade started from a straight-ahead position; the lead time decreased considerably as the initial eye and lid positions shifted downward. The firing rate usually reached its peak (130-280 spikes/s) at the very onset of the burst and declined gradually during the course of the saccade. The steady rate associated with the new fixation position was reached about halfway during the saccade. All units exhibited a pause in firing during the initial half of large downward saccades; during small saccades, the pause was inconspicuous or absent. 4. During vertical sinusoidal smooth pursuit, levator motoneurons exhibited a sinusoidal modulation in firing rate, which led eye position by an average of 23 degrees at 0.3 Hz. The average velocity sensitivity calculated from such data was 0.63 spikes/s per deg/s. 5. Although they exhibit a number of qualitative similarities, the discharge patterns of levator motoneurons and superior rectus motoneurons differ in several respects. First, during a blink, when the lid undergoes a large depression but the eye exhibits only a brief transient displacement, levator motoneurons cease firing completely, whereas superior rectus motoneurons continue to discharge. Second, for all types of coordinated lid and eye movements, levator motoneurons discharge at lower firing rates than do superior rectus motoneurons. Third, during saccades, levator motoneurons have less conspicuous and shorter-lasting bursts and pauses than do motoneurons involved in rotating the eye. 6. During upward gaze, the qualitative similarity of their burst-tonic discharge patterns suggests that levator and superior rectus motoneurons receive input signals that originate from a common source, but that the signals are processed differently to deal with the different loads facing these muscles.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1992

Endogenous nitric oxide required for an integrative respiratory function in the cat brain.

1. The involvement of nitric oxide (NO) in the respiratory function of the pons was examined by microinjecting NO synthase-related drugs into discrete regions of the pontine respiratory group (PRG) in decerebrate and decerebellate cats. 2. Microinjection of N omega-nitro-L-arginine (L-NNA, inhibitor of NO synthase), but not D-NNA (the inactive enantiomer), significantly prolonged the duration of inspiration in all 10 cats when lung inflation was withheld. 3. The prolongation of inspiration produced by L-NNA was partially reversed in three cats by microinjections of L-arginine (NO synthase substrate) at the same sites. 4. We conclude that endogenous production of NO from L-arginine in the PRG region is involved in the normal function of the pontine pneumotaxic mechanism. These findings provide the first conclusive evidence that endogenous NO formation is involved in the mechanisms associated with respiratory rhythm generation.

Animals↗
PubMed1992

Beta 2-adrenergic receptor mRNA is overexpressed in neoplastic human thyroid tissues.

The expression of beta 2-adrenergic receptor (AR) mRNA was investigated in normal and neoplastic human thyroid tissues. A combination of techniques for reverse transcribing mRNA into cDNA and the incorporation of 32P-gamma ATP into the polymerase chain reaction (PCR)-generated fragments allowed us to detect beta 2-AR mRNA in surgically excised thyroid specimens. The levels of beta 2-AR cDNA generated by PCR in thyroid adenomas and cancers were 3.3 and 6.9 times, respectively, as high as that of normal thyroid tissues. These findings suggest that the level of beta 2-AR mRNA is correlated with the extent of differentiation in neoplastic tissues. The present study provides new insights into the relationships between the AR-adenylate cyclase system and the regulation of the growth and differentiation in neoplastic human thyroid tissues.

Base Sequence↗
PubMed1992

Rat liver nodules induced by 2-acetylaminofluorene lose an ability to take up indocyanine green in the process of hepatocarcinogenesis.

Indocyanine green (ICG) was injected into rat liver nodules induced by 2-acetylaminofluorene (2-AAF) via portal vein. The relationship between ICG staining and cell atypism of liver nodules was examined by means of histology and DNA flow cytometry. After 2-AAF administration, many small nodules appeared on the liver surface. All hyperplastic nodules were ICG stained until 10 weeks after the administration, but some nodules were not stained after 14 weeks. ICG-stained nodules histologically consisted of benign tissues and borderline lesions, and many of them showed "diploidy" in DNA cytometry. ICG-unstained nodules consisted of hepatocellular carcinoma (HCCs) and borderline lesions, and many of them showed "aneuploidy". In this way, it has been suggested that HCC could derive from hyperplastic nodules and that they might lose an ability to take up ICG in the process of hepatocarcinogenesis. Immunohistochemical staining for glutathione-S-transferase alpha (GST-alpha), a carrier protein of ICG in hepatocytes, was well correlated with ICG staining in the nodules, suggesting that the loss of ICG uptake in HCC was partly due to the decrease of GST-alpha. Moreover, the appearance of ICG unstained and aneuploid nodules was significantly inhibited in rats which were fed on diet containing Syosaiko-to after the administration of 2-AAF. Chemopreventive effect of Syo-saiko-to on hepatocarcinogenesis was identified.

2-Acetylaminofluorene↗
PubMed1992

Maximum anal sphincter strength measured by the solid sphere test and anal pressure profiles.

OBJECTIVE: To evaluate two methods of quantifying external anal sphincter function. DESIGN: Open study. SETTING: Helsingborg Hospital, Sweden. SUBJECTS: 73 patients (63 women and 10 men), of whom 25 were incontinent of gas and liquid or solid stool. INTERVENTIONS: Anal pressure profiles and the "solid sphere" test. OUTCOME MEASURE: Correlation between results of tests and presence of incontinence. RESULTS: Continent patients were younger than incontinent ones. The correlation between the maximum force the patient could retain and the maximum anal squeeze pressure was good (r = 0.67, p < 0.001). Younger continent patients (n = 48) and significantly higher pressures than incontinent patients (n = 25), but the range and overlap were wide. The reproducibility of both methods was good. CONCLUSIONS: Although the solid sphere test is easier and quicker to do, anal pressure profiles yield more information that is important in the evaluation of incontinence.

Adult↗
PubMed1991

Estrogen receptors in the external anal sphincter.

Inasmuch as anal competence in women is reduced after the age of 50 years, it may be dependent on effects of estrogens. In this study, samples of the external anal sphincter were analyzed for the presence of estrogen receptors and were found to be present at a median concentration of 5.0 fmol per milligram of protein (range, 1.9 to 13) in women (n = 7), and 1.1 fmol per milligram of protein (range, 0 to 3.2) in men (n = 7). These findings are of interest with regard to the treatment of idiopathic anal incontinence.

Adult↗
PubMed1991

Anal sphincter competence in healthy women: clinical implications of age and other factors.

Normal variation in anal sphincter competence was examined with anal pressure profilometry, using a low compliant recording system and a perfused catheter, in 49 healthy women with a mean age of 51 years (range 20-79). Maximum resting anal pressure and maximum squeeze pressure declined with age (r = -0.61; P less than .001 for both), more rapidly so after menopause. Rectal pressure increased with body mass index (r = 0.60, P less than .001). Closing pressure (ie, the difference between maximum resting anal pressure and rectal pressure), an important determinant of anal continence, was more markedly reduced with age (r = -0.69, P less than .001) than was maximum resting anal pressure. Age-related changes were found for the length of the anal canal (r = -0.36, P less than .05). Parity and anal pressures were unrelated. Women are more frequently affected by anal incontinence than are men. Anal pressure profilometry is a useful diagnostic aid, though age-related changes must be taken into consideration when evaluating the results. The more rapid decline of anal pressures after menopause might imply that anal sphincter tissue is a target for estrogen.

Adult↗
PubMed1990

[Constituents of the seed coat of Arachis hypogaea L].

From the seed coat of Arachis hypogaea two compounds were isolated. They were identified as the dimer of proanthocyanidin-A type(I) and D-(+)-catechin (II) on the basis of UV, IR, MS, CD, 1H-NMR, 13C-NMR and chemical evidences. It has been found that II is the effective constituent of this plant and I has some active effects as well.

Anthocyanins↗
PubMed1989

[Cytosol estrogen, progestin receptors and secretory endometrium in infertile women].

The serum levels of estradiol (E2), progesterone (P), FSH, PRL and cytosol estrogen and progestin receptors (EcR, PcR) contents in the endometrial tissues were analyzed in patients with inadequate secretory endometrium. The result shows that EcR and PcR are significantly lower (EcR: P less than 0.01; PcR: P less than 0.05) in these patients than those of control group. The inadequate secretory changes of endometrium correlated with insufficient EcR and PcR contents rather than with decreased levels of serum E2, P, FSH and PRL. The authors suggest that during treatment of such patients both the hormonal levels in the peripheral blood and the EcR, PcR contents in the tissue should be considered at the same time.

Adult↗
PubMed1988

Expression of Ia and monocyte-macrophage lineage antigens in giant cell tumor of bone and related lesions.

An immunohistochemical study of six giant cell tumors of bone and eight related lesions (aneurysmal bone cyst, fibrous histiocytoma, and giant cell tumor of tendon sheath) was performed using a panel of monoclonal antibodies directed to the Ia and monocyte-macrophage lineage antigens. In all types of lesion, osteoclastlike multinucleate giant cells were negative for both types of antigen, but a proportion of mononuclear cells gave positive reactions. While the possibility that these cells are reactive cannot be excluded, in giant cell tumor and malignant fibrous histiocytoma, their frequency and their morphologic similarity to the rest of the tissue suggest that they may be an intrinsic part of the neoplasm. This finding is consistent with the presumed fibrohistiocytic nature of these tumors.

Acid Phosphatase↗