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Biomedical subjects

B Y Zhou

Publications and source records attributed to B Y Zhou.

12 recordsLinked to original sources
PubMed1998

Specific antibodies to the external vestibule of voltage-gated potassium channels block current.

Using delayed-rectifier potassium channels as examples, we have designed two specific blockers by generating specific antipeptide antibodies to epitopes in the external vestibules of two channel proteins, Kv1.2 and Kv3.1. These antibodies reduced whole-cell Kv1.2 or Kv3.1 currents in transfected cells and the effect was blocked by the corresponding peptide antigen, but not by control peptides. A control antibody had little effect on Kv1.2 currents and the Kv1.2 blocker antibody had limited effect on other related potassium currents. Furthermore, the Kv1.2 blocking antibody inhibited dendrotoxin binding to Kv1.2 channel proteins in transfected cells. Moreover, using the Kv1.2 blocker antibody, we determined the presence and relative contribution of endogenous Kv1.2 to the overall endogenous K+ currents in NG108 neuronal cells. This guided design of specific channel blockers will facilitate future physiological studies on ion channel functions.

Amino Acid Sequence↗
PubMed1997

Machado-Joseph disease in four Chinese pedigrees: molecular analysis of 15 patients including two juvenile cases and clinical correlations.

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder associated with the expansion of a (CAG)n array in the MJD1 gene. We analyzed the sizes of the (CAG)n array using DNA samples from 61 members of four Chinese MJD families and 18 Chinese normal control subjects and confirmed that the (CAG)n array in 15 MJD chromosomes was expanded to 72-86 repeat units. There were no subjects with (CAG)n array sizes intermediate between those of normal and MJD affected groups. Meanwhile, we found a significant negative correlation between the age of onset of symptoms and (CAG)n array size. The largest (CAG)n array of 86 repeat units was in the youngest patient, whose age of onset was 5 years. The intergenerational increase in number of CAG repeat units was associated with the clinical phenomenon of anticipation.

Adolescent↗
PubMed1994

Effects of gadolinium on length-dependent force in guinea-pig papillary muscle.

The degree to which stretch-activated channels operate during physiological length changes in multicellular heart preparations, or how much the channels could contribute to length-dependent activation, is not known. We studied the relationship between muscle length and contractile force in guinea-pig papillary muscles superfused with gadolinium chloride (10 microM), a stretch-activated channel blocker, and compared the effects to those with nifedipine (0.25 microM), a calcium channel blocker. Gadolinium reduced contractile force statistically significantly more at the longer muscle lengths than at the short muscle lengths. This did not apply with nifedipine, although a marginally greater effect at longer lengths was perceptible. The results can only partly be explained by gadolinium having a non-specific action via the calcium channel, or Na(+)-Ca2+ exchange, and are consistent with the possibility that stretch-activated channels contribute to length-dependent activation in cardiac muscle, and thus to 'Starling's Law of the Heart'.

Animals↗
PubMed1991

Studies on properties of thermostable beta-amylase from Thermoactinomyces sp.V4.

A thermostable beta-amylase from Thermoactinomyces sp. V4 isolated from soil is reported. The enzyme has optimum activity at 70 degrees C and pH6. It is stable at 50 degrees C (4h) and retains 92% of activity at 55 degrees C (2h). The extent of hydrolysis soluble starch is about 77% and the product is identified as beta-maltose by paper chromatography and rotatory examination. Sulfhydryl reagent has no effect on the beta-amylase activity.

Bacteria, Aerobic↗
PubMed1991

[The prognostic significance and correlation of ventricular late potentials with programmed electrical stimulation in patients after myocardial infarction].

Seventeen patients (pts) after myocardial infarction (MI) were studied with signal-averaged electrocardiograph and cardiac programmed electrical stimulation (PES). In 7 pts with late potentials (LPs), sustained ventricular tachycardia (SVT) was induced in 6 cases (6/7, 85.7%); while it was induced only in 3 cases the 10 pts without LPs (3/10, 30%). Both have significant difference (P less than 0.01). During following observation, pts with LPs and SVT induced 5 of the 6 appeared clinical SVT or ventricular fibrillation (VF) repetitiously, and 1 died from sudden cardiac death. They also have significant difference (P less than 0.001) with pts without LPs and SVT not induced. These results suggests that LPs is a significant index for predicting future events and its combination with PES is helpful to screen high-risk pts after MI.

Adult↗
PubMed1989

[An investigation of medicinal concha ostreae of Xinghua City, Jiangsu Province].

The investigation shows that this concha ostreae is actually the remains of the geomorphological evolution of the Jiangsu plain, or the fossil of ancient concha ostreae shells, and therefore differs considerably from the medicinal concha ostreae specified in current Chinese Pharmaconeia. The safe and effective use of concha ostreae remains to be studied further.

Animals↗
PubMed1989

[Analysis of Ostrea gigas Thunberg from Xinhua, Jiangsu].

This paper compares the ultramicrostructure, infrared spectrum and Meigen reaction of the ancient Ostrea gigas shell from Xinhua County, Jiangsu Province, with those of fresh Ostrea gigas shell from Fujian Province. It was shown that the histomorphology of the ancient Ostrea gigas shell is the same as that of the fresh one and both shells are composed of calcite.

Animals↗