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Biomedical subjects

X M Cheng

Publications and source records attributed to X M Cheng.

At least 37 records · Page 2Linked to original sources
PubMed1995

Azaphilones with endothelin receptor binding activity produced by Penicillium sclerotiorum: taxonomy, fermentation, isolation, structure elucidation and biological activity.

A series of azaphilones produced by Penicillium sclerotiorum (Xenova culture collection number X11853) active in assays for the detection of antagonists of the endothelin-A (ETA) and endothelin-B (ETB) receptors has been identified. The series includes two novel sclerotiorin analogues, (8S,8 alpha-R)-7-deacetyl-1,O8,8,8a-tetrahydro-7-epi-sclerotiorin, 1, and its 5-dechloro analogue, 2. It also includes 5-chloroisorotiorin, 6, previously unreported as a natural product, in addition to the major product of these fermentations, (+)-sclerotiorin, 5. Data for the inhibition of endothelin-1 (ET-1) and endothelin-3 (ET-3) binding in the ETA and ETB receptor assays respectively are reported for this series. Compounds 1 and 2 were more selective for the rabbit ETA receptor than for the rat ETB receptor. The IC50 values for 1 and 2 were 9 and 28 microM respectively in an assay based on binding of ET-1 to rabbit ETA receptors. In an assay based on the binding of ET-3 to the rat ETB receptor compounds 1 and 2 exhibited IC50's of 77 and 172 microM. Members of this series of compounds demonstrated antagonist behavior in a secondary assay based on blockade of ET-1 stimulated arachidonic acid release from rabbit renal artery smooth muscle cells, when present at concentrations of > or = 30 microM.

Animals↗
PubMed1993

In vitro and in vivo studies with a series of hexapeptide endothelin antagonists.

The effects of different amino acids incorporated into the 16 and 17 positions of the C-terminal hexapeptide of ET-1 were examined. Structure-activity relationships (SAR) of the ET receptor antagonists PD 142893 [Ac-(D-Dip16-L-Leu17-L-Asp-L-Ile-L-Ile-L-Trp) (D-Dip = 3,3-D-diphenylalanine)] and PD 145065 [Ac-(D-Bhg16-L-Leu17-L-Asp-L-Ile-L-Ile-L-Trp) (D-Bhg = 5H-dibenzyl[a,d]cycloheptene-10,11-dihydro-glycine)] uncovered certain requirements for high potency. The disodium salt of PD 145065 has 4.0 and 15 nM binding affinity (IC50 values) for the ETA (rabbit renal artery vascular smooth-muscle cells) and ETB receptor (rat cerebellum), respectively. The compound is also an antagonist of ET-1- and SRTX-6c-stimulated vasoconstrictor activity, with pA2 values of 6.9 (rabbit femoral artery, ETA assay) and 7.1 (rabbit pulmonary artery, ETB assay). The tripeptidic ETA antagonist FR 139317 was found to be less active in the rabbit femoral artery, with a pA2 value of 6.0, and inactive in the rabbit pulmonary artery. Substitution of acidic and basic residues at position 17 in PD 142893 and PD 145065 indicates differences in selectivity. Incorporation of bulky non-natural amino acids at position 16 has led to potent nonselective analogues, including Ac-D-Bheg16-L-Leu-L-Asp-L-Ile-L-Ile-L-Trp [D-Bheg (5H-dibenzo[a,d]cycloheptene glycine)]. The in vivo effects of single-bolus doses of selected ET antagonists on depressor and pressor responses to ET-1 in anesthetized ganglion-blocked rats were evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

A case-control study on the environmental risk factors of Parkinson's disease in Tianjin, China.

Using a case-control method, we studied the role of environmental risk factors and viral infection in the development of Parkinson's disease (PD) in China. Ninety-three PD patients and 186 controls were investigated with a questionnaire and from most of them, blood was taken to test the antibody levels of four virus (measles, rubella, HSV-1, CMV) IgG. The study result showed that positive family history, living near rubber plants, drinking river-water were associated with an increased risk of developing PD. In contrast, living in small cities, drinking well-water, drinking hard-liquor frequently, were associated with a decreased risk for PD. PD cases and controls did not differ with respect to other factors investigated including smoking and viral infection. These findings suggest that some environmental factors may be related to the development of PD, but further standardized studies will be required to confirm our results.

Adult↗
PubMed1992

Seventh cervical nerve root transfer from the contralateral healthy side for treatment of brachial plexus root avulsion.

Cervical root nerve transfer from the contralateral side has been used for the treatment of brachial plexus root avulsion in 49 patients. Resection of C7 root from the healthy side has produced no long-term symptoms or signs. Nine patients with ten recipient nerves have been followed up for more than two years and seven have obtained a functional recovery. This operation offers a new approach for the treatment of brachial plexus root avulsion.

Adolescent↗
PubMed1992

[Zero-crossing derivative spectrophotometry for the determination of three components in paracetamol compound tablets].

The zero-order derivative absorption spectra of aspirin, paracetamol and caffeine are closely overlapping. In this paper, a zero-crossing derivative spectrophotometry combined with simultaneous equations is proposed for the determination of the three components in a mixture without the need of prior separation. Satisfactory results were obtained. The method is reproducible, accurate and rapid. Calculation is not complicated. This method could be applied to biological fluid analysis.

Acetaminophen↗
PubMed1991

Cervical nerve root transfer from contralateral normal side for treatment of brachial plexus root avulsions.

The authors had designed cervical root nerve transfer from the contralateral normal side for the treatment of brachial plexus root avulsions in August 1986. Since then, the operation was performed in 50 cases. Follow-up studies showed that resection of C-7 root from the healthy side produced no long-term ill effect except numbness and pain of the fingers and weakness of gripping strength shortly after the procedure. In 10 recipient nerves of 9 cases with follow-ups of more than 2 years, satisfactory results were seen in 7. This is a new approach for the treatment of persistent cases of brachial plexus avulsion.

Adolescent↗
PubMed1990

Risk factors for stroke in rural areas of the People's Republic of China: results of a case-control study.

A case-control study on stroke was carried out in 1985 in conjunction with a prevalence survey on neurologic disorders in 22 rural communities of the People's Republic of China. 585 cases of stroke, detected from the survey, together with an equal number of matched controls were investigated. The statistically significant factors associated with stroke in this study were: hypertension (history, findings at examination); high salt intake; family member(s) with cerebrovascular disease and/or hypertension; heart disease (history, abnormal findings at examination); history of transient ischemic attacks, and arteriosclerotic funduscopic findings. These factors were analyzed separately for hemorrhagic and ischemic strokes.

Case-Control Studies↗
PubMed1990

[Determination of two major metabolites of A-OT-Fu in mice serum by 4th order derivative UV spectrophotometry].

A 4th order derivative UV spectrophotometric method was developed for the determination of two major metabolites (TFu and 5-Fu) of A-OT-Fu in mice serum following per os of 290 mg/kg of the drug. TFu and 5-Fu were extracted from mice serum by ethyl acetate. The amplitudes of 252 and 289 nm for axle are linear with concentration of TFu and 5-Fu within the range of 5-50 micrograms/ml. Under the given experimental condition the recovery of TFu and 5-Fu were over 95%. The maximum concentration of TFu and 5-Fu appeared at 1 h and 2 h respectively after administration.

Animals↗
PubMed1990

Phrenic nerve transfer for treatment of root avulsion of the brachial plexus.

Phrenic nerve transfer was performed in 164 patients with root avulsion of the brachial plexus. The methods of operation consisted of phrenic nerve transfer to and anastomosis with the musculocutaneous nerve, the phrenic nerve bridging to the musculocutaneous nerve, phrenic nerve anastomosis with or bridging to the median nerve, and phrenic nerve anastomosis with other nerves. Follow-up of 65 patients for more than 2 years showed an effective rate of 84.6%. The result indicated that this operation has no deleterious effects on respiration, and the surgical effects are related to severity of injury, duration, mode of operation and patient's age.

Adolescent↗
PubMed1990

Root avulsion of brachial plexus in infants and children.

Twenty-one patients, under 6 years of age, with root avulsion of the brachial plexus were treated from 1975 to 1987. Among them, 9 had root avulsion of the upper trunk, 2 root avulsion of the lower trunk with middle trunk broken, and 10 root avulsion of the whole brachial plexus. Follow-up of 16 patients showed excellent results in 2 patients, good in 11, fair in 1 and poor in 2. It is suggested that good results can be obtained if multi-paired nerve transfer is adopted in treatment. We conclude that owing to anatomical and physiological characteristics of the respiratory system in children, it is harmful to perform phrenic nerve transfer concomitantly with intercostal nerve transfer. Advisably, two-stage operation is required, otherwise dyspnea and pneumonia are liable to occur. In addition, the time of the operation could be extended to 4-5 years after injury in children, but best results are obtained if the operation is performed within 1 year.

Accidents, Traffic↗
PubMed1989

Phrenic nerve transfer for brachial plexus motor neurotization.

We report a series of 164 patients who underwent phrenic neurotization to elements of the brachial plexus with root avulsion injuries. Recipient nerves included musculocutaneous nerve in 125 patients (78 direct neurotizations and 48 with intervening autograft), median nerve in 10 patients, and a variety of other nerves in 28 patients. Sixty-five patients presented a follow-up period of 2 or more years. Of this group, 55 patients (84.6%) achieved a recovery of M-3 or better. We observed no long-term deleterious effects on respiratory function.

Adolescent↗
PubMed1989

Serum cholesterol, its lipoprotein fractions among survivors of cerebrovascular disease. A case-control study.

A case-control study was conducted in 1983 on 210 cerebrovascular disease (CVD) patients identified from a retrospective cross-sectional door-to-door survey of four cities in the People's Republic of China. One hundred and eleven male (mean age 63.8 +/- 8.9 years) and 99 female (mean age 63.5 +/- 11.1 years) CVD survivors and controls matched for sex, age, race and area were selected. Total serum cholesterol, high-density lipoprotein and low-density lipoprotein cholesterol were measured to see if there were differences between lipids in survivors of CVD and their matched controls. There was a higher level of total cholesterol in cerebral thrombotic patients (n = 114) and a lower level of total cholesterol and high-density lipoprotein cholesterol in cerebral hemorrhagic patients (n = 35) than in controls, although the results were not statistically significant. The only higher level of total serum cholesterol that might be important was in the group of male thrombotic patients of age greater than 70 years (n = 22; nominal p value less than 0.05). The implication of this finding needs further clarification.

Adult↗
PubMed1989

Arterialized free flap. Report of four cases.

In 1985, we applied an arterialized vein stem free flap in 4 cases with success in 3. In making this flap the superficial vein with the covered skin of the limb was used. In operation the flap was inverted and the 2 ends of the vein stem were anastomosed with the artery of the recipient area. Rapid arterial blood flow not only provided blood supply to the flap, but through the "venous network shunt" and "tidal pressure difference of artery" maintained blood circulation of the flap. The details of technique and the changes of blood circulation after flap transfer are described, as are indications advantages and mechanism of blood circulation of the flap, and factors affecting the circulation.

Adolescent↗
PubMed1989

Microsurgical treatment of brachial plexus irreversible avulsion.

A new combined measure of nerve transfer, including antebrachial medial cutaneous nerve, and free musculocutaneous flap transfer was applied to the treatment of irreversible avulsion of the brachial plexus. 12 patients underwent this operation for restoring elbow and finger flexion. Good result was obtained in 71% for elbow and 60% for finger flexion restoration. The definition of irreversible avulsion and the methods, key points and value of the operation are described and discussed in detail.

Brachial Plexus↗
PubMed1986

Brain injury due to head trauma. Epidemiology in urban areas of the People's Republic of China.

A door-to-door survey was carried out in six cities of the People's Republic of China during 1983 in a well-defined population of 63,195 to determine the prevalence of frequently occurring neurologic disorders, including brain injury. In the survey, trained health workers conducted a complete census and administered a questionnaire that had been pretested to assure a high level of sensitivity in identifying individuals suffering from brain injury due to head trauma. All those with responses suggesting brain injury were examined by senior neurosurgeons who used uniform diagnostic criteria and reviewed available medical records to establish a diagnosis. There was 100% cooperation with the screening and diagnostic phases of the survey. Based on this investigation, the age-adjusted (to the 1960 US population) prevalence ratio for brain injury due to head trauma is seven per 1,000, and the incidence rate is 56 per 100,000 per year. The ratios and rates are higher in male than female subjects. The main cause of brain injury due to head trauma in the People's Republic of China is bicycle accidents.

Adolescent↗