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Biomedical subjects

K Yan

Publications and source records attributed to K Yan.

At least 19 recordsLinked to original sources
PubMed1995

Hypercalciuria and nephrocalcinosis in patients with idiopathic low-molecular-weight proteinuria in Japan: is the disease identical to Dent's disease in United Kingdom?

Idiopathic low-molecular-weight (LMW) proteinuria is a newly described renal disease in Japan and Italy. We report on 7 patients who manifested bilateral or unilateral nephrocalcinosis, as demonstrated by abdominal computed tomography scans. Renal histology revealed calcinosis of renal tubules in 2 patients. Computed tomography is a reliable method for the detection of nephrocalcinosis in this disorder. Hypercalciuria was also seen in 6 patients. A calcium-loading test performed in 2 patients suggested that hypercalciuria was of renal origin. Although the true pathogenesis is still not known, hypercalciuria and nephrocalcinosis appear to be a common complication in patients with idiopathic LMW proteinuria. These complications and clinical features suggest that idiopathic LMW proteinuria in Japan is likely to be identical to Dent's disease in the United Kingdom.

Adolescent↗
PubMed1994

Differential ultrasonic diagnoses of pulmonary benign and malignant space-occupied lesions of the peripheral type.

87 patients with pulmonary space-occupied lesions of the peripheral type which were either adhesive or close to pleura were examined using ultrasonography. Of them, 64 cases of lung cancers and 23 of benign lesions were then confirmed by histopathology. Five sonographic features, including configuration, echogenicity patterns, bronchial air phase in foci, margin, and pleural involvement, were significantly different between malignant and benign diseases (P < 0.01). The differential ultrasonography used in this series showed a sensitivity of 61% (14/23), a specificity of 95% (61/64), and an accuracy of 86% (75/87). The results of the study demonstrate that the ultrasonography is helpful in differentiating malignant and benign peripheral lung lesions near the plerua.

Adenocarcinoma↗
PubMed1994

Transcutaneous ultrasound of the cervical esophagus in patients with esophageal carcinoma.

Transcutaneous ultrasound of the cervical esophagus was performed in 46 patients with esophageal carcinoma and in 35 controls. The former had 24 upper segmental lesions and 22 lower segmental lesions. The level of the sternoclavicular joint was used to divide the esophagus into the upper segmental (USE) and lower segmental esophagus (LSE). The anterior esophageal wall thickness and luminal dimensions were measured before and immediately after phonation. The mean wall thickness in the controls was 1.8 mm before phonation and 2.1 mm after phonation, with a significant difference (t test, P < 0.05). The mean wall thickness in the USE carcinoma group was 4.3 mm and 4.4 mm before and after phonation respectively. There was a significant difference between the controls and USE carcinoma groups (t test, P < 0.05). The cross sectional area, which was calculated as the product of anterio-posterior and lateral diameters, averaged 28 mm2 before phonation in the controls and increased to 44 mm2 after phonation (t test, P < 0.05). The mean cross sectional area in the USE carcinoma group was significantly smaller before phonation than that in the controls (t test, P < 0.05) and showed little change after phonation. No significant difference was found between LSE carcinoma and control groups. Transcutaneous ultrasound appears to be a promising non-invasive method of investigation for cervical esophageal carcinoma.

Adult↗
PubMed1994

[Manifestation of abdominal segment of esophagus by body surface ultrasonography and determination of normal values].

Scanning over the oblique section of xiphoid-left costal margin by body surface ultrasonography was adopted in the present study. The esophageal hiatus showed triangle-like strong echo which was called by the author "Hom Dill Casoue". Its dorsal aspect could be confirmed as the abdominal segment of the esophagus. In a general survey of 268 cases of high risk crowd in high incidence area, 82% (217 cases) were manifested clearly. The mean wall thickness was 2.58 +/- 0.54mm, and the mean length 23.7 +/- 5.6mm. Among the 9 cases suspicious of increased thickness, 5 were confirmed to have esophageal lesions. Among them there were 2 cases of esophageal carcinoma, and 2 cases of inflammatory ulcer with edema, and one case of hiatal hernia. The accuracy rate of diagnosis for those with clear manifestation by ultrasonography reached as high as 98% (218/222 cases). This method provides a new measure for the general survey of esophageal diseases in the abdominal segment.

Adult↗
PubMed1994

[Ultrasonography in differential diagnosis of peripheral pulmonary diseases].

In 87 patients with peripheral pulmonary diseases either adhesive or close to the pleura, who were examined, ultrasonographically 64 had lung cancer and 23 benign lesions were confirmed histopathologically. Five sonographic features including configuration, echogenicity patterns, bronchial air phase in foci, margin, and pleural involvement were significantly different between malignant and benign diseases (P < 0.01). The differential ultrasonography used in this series showed a sensitivity of 61% (14/23), a specificity of 95% (61/64), and an accuracy of 86% (75/87). The results demonstrate that ultrasound is helpful in differentiating the malignant lesion from the benign one in the peripheral lung near the pleura.

Adenocarcinoma↗
PubMed1992

Effect of gold compounds on the activity of adenylyl cyclase in human lymphocyte membranes.

OBJECTIVE: To determine the effects of aurothioglucose, aurothiomalate, and auranofin on basal and forskolin-activated adenylyl cyclase activity in human total lymphocyte membranes, and in membranes of T and B lymphocyte subsets. METHODS: Membranes were isolated from human total lymphocytes and T and B cell subsets. The effects of gold compounds on basal and forskolin-stimulated activity of adenylyl cyclase were measured by radioassay. RESULTS: The gold compounds inhibited adenylyl cyclase activity. This inhibitory effect required the presence of both the sulfhydryl ligands and aurous cation. CONCLUSION: Regulation of lymphocyte adenylyl cyclase by gold compounds represents a potential mode of action of these drugs in rheumatic diseases.

Adenylyl Cyclases↗
PubMed1992

Flavonol glycoside production in callus cultures of Epimedium diphyllum.

Callus cultures of Epimedium diphyllum produced a large amount of epimedoside A in addition to a small amount of diphylloside B, ikarisoside C, epimedoside E, diglycosides of des-O-methylanhydroicaritin (8-gamma, gamma-dimethylallylkaempfero). Icariin, epimedins A-C, which are glycosides of anhydroicaritin, were also produced in the callus cultures. Contents of the flavonol glycosides in callus tissue were higher than those of mother plants, but the composition of each flavonol glycoside mixture in the callus cultures was different from that of the original plants. The time-course experiments showed that an inverse relationship existed between cell growth and flavonol glycoside production. Effects of hormonal factors on cell growth and flavonol glycoside production indicated that 2,4-dichlorophenoxyacetic acid was needed for the production of flavonol glycosides.

Carbohydrate Sequence↗
PubMed1992

Blockers of potassium channels reduce the outward dark current in rod photoreceptor inner segments.

The dark current of single isolated toad rods was monitored by drawing either the inner segment or the outer segment into a suction electrode. The potassium-channel blockers tetraethylammonium (TEA) and 3,4-diaminopyridine (DAP) reduced the amplitude of the dark current when applied to the inner segment. Both drugs were less effective when applied to the outer segment, suggesting that they act at the inner segment to block part of the outward path for the dark current. In addition, DAP affected the kinetics of the light response, possibly by affecting internal pH.

4-Aminopyridine↗
PubMed1991

[Determination of cholesterol in natural bezoar by gas chromatography].

A gas chromatographic method for the determination of free and total cholesterol in natural bezoar has been established in this report. The method is simple, specific and accurate. The free and total cholesterol contents in three kinds of bezoar are between 0.072% to 0.214% and 0.546% to 0.608% respectively.

Animals↗
PubMed1990

Tubulin binds specifically to the signal-transducing proteins, Gs alpha and Gi alpha 1.

Participation of cytoskeletal elements in regulation of hormonal response and responsiveness has been suggested by several laboratories. Addition of dimeric tubulin to rat cerebral cortex synaptic membranes causes stable inhibition of adenylyl cyclase, and the molecular basis for this effect appears to require a direct interaction between tubulin and G proteins. To test whether such tubulin-G protein interaction occurred, several purified G proteins were bound to nitrocellulose, and 125I-tubulin overlay studies were performed. 125I-Tubulin bound to the alpha subunits of Gs and Gil with high specificity and an apparent Kd of approximately 130 nM. Other G protein alpha subunits (alpha i2, alpha i3, alpha 0, and transducin) displayed a much lower affinity for tubulin, despite the much closer relationship of those proteins to alpha il than to alpha s. Association of beta gamma subunits with alpha il or alpha s did not alter the binding of tubulin to these G protein heterotrimers, and the binding of a hydrolysis-resistant GTP analog to the alpha subunits was similarly without effect. These results suggest that tubulin forms complexes with specific G proteins and these complexes might provide a locus for the interaction of cytoskeletal components and signal transduction cascades. These results also provide evidence of a functional distinction among the closely related alpha i subtypes.

Animals↗
PubMed1990

[HPTLC densitometric determination of free bile acids in bezoar].

Cholic acid (CA), chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA) which are extracted with CH3OH from Bezoar can be separated on HPTLC silica gel plate (made in China) with isooctane-n-butyl acetate-acetic acid (4:2:1), and the three bile acids were determined by TLC densitometry.

Animals↗
PubMed1990

[Mosquito-net spraying with deltamethrin for malaria control].

Mosquito-nets were sprayed with 9.6mg deltamethrin per square meter for control of malaria vectors in Yibin County, Sichuan Province in 1986. In the study area, the relative population indices of Anopheles anthropophagus and An. sinensis in 35 mosquito-nets were 0.6 and 1.4 respectively; the man biting rates of these two vectors dropped by 97.8 and 90.8% respectively. The residual toxic effect of sprayed mosquito-nets, up to 104 days after spray, caused a mortality of 93.1-100% of An. anthropophagus and 87.1-100% of An. sinensis. The multiparous mosquito rate dropped by 48.4 and 51.3%. Indoor-intruding An. anthropophagus and An. sinensis were reduced by 76% and 78.3% respectively. The incidence of malaria decreased by 94.4%, the positive rate in school children declined by 77.5%. Both entomological and epidemiological indices indicated that mosquito-nets sprayed with deltamethrin could effectively control the malaria prevalence. This measure is economical and practical for control of malaria.

Animals↗
PubMed1988

Effect of therapy on bronchial hyperresponsiveness in the long-term management of asthma.

The aim of this study was to determine if prophylactic therapy leads to a reduction in the severity of bronchial hyperresponsiveness (BHR) in subjects with severe asthma. Measurements of bronchial responsiveness to histamine were made in two groups of subjects for periods up to 2 years. Thirteen subjects in the study group took regular medication and used a home monitor of airway function to determine the medication requirements needed to maintain optimal airway function. A control group of eleven subjects was managed with the same drugs but without daily monitoring and without any attempt to keep daily lung function at optimal levels. Subjects in the study group had a 10- to 100-fold decrease in the severity of BHR, which was independent of the improvement in baseline lung function. All but one subject in the study group became symptom free and six were able to maintain the improvement in BHR and symptoms on reduced medication. There was no change in the severity of BHR or in the baseline lung function in the control group. It is concluded that it is possible to reduce the severity of BHR in subjects with severe asthma by the use of pharmacological agents. This reduction in severity appears to require the long-term use of medications, including aerosol corticosteroids, with daily home monitoring to allow adjustment of the amount of treatment required.

Adult↗
PubMed1987

Prevalence of bronchial hyperresponsiveness and asthma in a rural adult population.

The prevalence of bronchial hyperresponsiveness in adult populations is not known. To document its prevalence and distribution and to determine the factors associated with it, a random sample of the adult population of Busselton, Western Australia, was studied. Spirometric function, bronchial responsiveness to histamine, and atopic responses to skin prick tests were measured. Respiratory symptoms were determined by questionnaire. Data were obtained from 916 subjects. Of these, 876 underwent a histamine inhalation test and bronchial hyperresponsiveness to histamine (defined as a dose of histamine provoking a 20% fall in FEV1 equal to or less than 3.9 mumol) was found in 10.5%. Another 40 subjects with poor lung function were tested with a bronchodilator and 12 were found to have bronchial hyperresponsiveness (defined as a greater than 15% increase in FEV1), making the total prevalence of bronchial hyperresponsiveness 11.4%. The prevalence of current asthma, defined as bronchial hyperresponsiveness plus symptoms consistent with asthma in the last 12 months, was 5.9%. The distribution of bronchial hyperresponsiveness in the studied population was continuous. There was a significant association between it and respiratory symptoms, atopy, smoking, and abnormal lung function (p less than 0.001 for all associations). There was no association with age, sex, or recent respiratory tract infection.

Adult↗
PubMed1986

Visual responses of neurons in the avian nucleus isthmi.

Electrophysiological responses of neurons to visual and auditory stimulation are extracellularly recorded from the pigeon isthmic area. Cobalt sulfide markings show that only visual units are localized within the nucleus isthmi pars parvocellularis (Ipc) and pars magnocellularis (Imc), while visual-auditory bimodal units are localized outside. Visual units respond to black or white targets moving through their receptive fields (RFs). The RF centers are mainly distributed in the contralaterally lower visual field. The rostral Ipc and Imc receive information from the nasal visual field, and the caudal part of the Ipc and Imc corresponds to the temporal field. Therefore, both Ipc and Imc are visual centers instead of auditory centers as described before.

Acoustic Stimulation↗
PubMed1985

The effect of acetylcholine on neurones of the amphibian nucleus isthmi.

In the bird, histochemical and biochemical data suggest that the tectal input into nucleus isthmi is of a cholinergic nature. In the present study the response of toad (Bufo bufo gargarizans) isthmic neurones to acetylcholine was investigated using conventional extracellular recording techniques and ionophoresis. The results show isthmic cells to be strongly excited by acetylcholine (ACh), whereas neurones in the neighbouring areas show minimal sensitivity. Atropine sulphate completely blocked the response to acetylcholine and greatly decreased activity induced by visual stimulus. The present data show that acetylcholine mimics one of the physiological transmitters in the nucleus isthmi.

Acetylcholine↗
PubMed1985

Prevalence and nature of bronchial hyperresponsiveness in subjects with chronic obstructive pulmonary disease.

The prevalence, nature, and severity of bronchial hyperresponsiveness in subjects with chronic obstructive pulmonary disease (COPD) is not known. To determine these factors, a 1 in 4 random sample of adults attending the Busselton population survey was studied. Subjects answered a modified Medical Research Council questionnaire and had spirometric function tested. They were defined as having COPD or asthma from the questionnaire. Bronchial responsiveness to histamine was measured using the rapid method, and results in the subjects with COPD were compared with those in asthmatic subjects with abnormal lung function. Fifty-nine subjects with COPD had a histamine inhalation test, and of these, 27 had bronchial hyperresponsiveness (BHR) (PD20FEV1 less than 3.9 mumol). The position of the dose response curves of the subjects with COPD overlapped considerably with those obtained from the 17 asthmatics. The geometric mean values for PD20FEV1 for these 2 groups were significantly different (p less than 0.001). There was a good correlation between FEV1/FVC and PD20FEV1 values in the subjects with COPD but not in the asthmatic subjects. Pretreatment with 600 micrograms of aerosolized fenoterol significantly improved the PD20FEV1 values in 11 subjects with COPD (1.26 to 6.16 mumol; p less than 0.001). The results suggest that approximately half the subjects with COPD in a general population have BHR but this BHR has different characteristics from that occurring in asthmatic subjects.

Adult↗