Biomedical subjects

H Pan

Publications and source records attributed to H Pan.

134 records · Page 8Linked to original sources

PubMed1990

Physiological role of vitamin A in growth cartilage cells: low concentrations of retinoic acid strongly promote the proliferation of rabbit costal growth cartilage cells in culture.

We have demonstrated that high concentrations of retinoic acid (RA) inhibit expression of the differentiated phenotypes of rabbit costal chondrocytes in culture [M. Takigawa et al. (1980) Proc. Natl. Acad. Sci. U.S. 77, 1481-1485]. In this study we examined the effects of low concentrations of RA on rabbit costal chondrocytes cultured in medium containing vitamin A-deficient serum. In vitamin A-deficient medium, chondrocytes isolated from growth cartilage (GC) proliferated only very slowly, and RA strongly stimulated their proliferation. This stimulatory effect was observable at a concentration of 10(-10) M RA and maximal at a concentration of 10(-8) M. RA at 10(-8) M did not change GC cells from a typical polygonal shape to fibroblast-like cells or inhibit their synthesis of type II collagen. Moreover, RA-treated cells did not synthesize type I collagen. RA inhibited glycosaminoglycan (GAG) synthesis by the cells dose-dependently, but did not change the distribution profile of proteoglycan monomers as determined by glycerol gradient centrifugation. The inhibitory action of RA on GAG synthesis was reversible: after removal of RA from the culture, the rate of GAG synthesis increased within 2 days. In contrast, resting cartilage (RC) cells proliferated well in vitamin A-deficient medium without addition of RA, and RA (10(-8) M) stimulated their proliferation only slightly. Furthermore, the inhibitory effect of RA on GAG synthesis in RC cells was much weaker than that in GC cells. These observations suggest a physiological role of RA in cartilage in stimulating the proliferation of GC cells without causing drastic change in their differentiated phenotypes.

Animals↗

PubMed1990

[Frequency- and voltage-dependent effects of changrolin on maximal upstroke velocity of action potentials in guinea pig papillary muscles].

Changrolin (CRL) is a new antiarrhythmic drug originated in China in 1970s. The effects of CRL on maximal upstroke velocity (Vmax) of action potentials were studied with standard microelectrode and computer in guinea pig papillary muscles. CRL depressed the Vmax. This effect was dependent on the rate of stimulations. The onset of use-dependent depression was monoexponential and dependent on drug concentration and rate of stimulations. The rate of recovery from use-dependent depression also followed a single exponential time course. CRL shifted the curve relating normalized Vmax to membrane potential in the hyperpolarizing direction. The onset rate was 0.156 +/- 0.025 AP-1 (RDB 50%), and offset rate (tau r) was 4.7 +/- 0.9 s. These suggest that CRL belongs to class Ia antiarrhythmic drugs.

Action Potentials↗

PubMed1986

[Radiotherapy of olfactory neuroblastoma--report of 5 patients].

Olfactory neuroblastoma is a rare tumor arising from the olfactory mucosal epithelium. 5 patients with this tumor were treated in our hospital from 1978 to 1982. The youngest patient was 3 years old and the eldest was 66. The clinical symptoms were nasal stuffiness, rhinorrhea, epistaxis and vascular polypoid mass in the nasal cavity. According to the staging system proposed by Kadish et al, the five patients in this series were 3 stage A and 2 stage C patients. Treatment consisted of radiotherapy, surgery or combination of radiotherapy and surgery. Our data indicate that the olfactory neuroblastoma is a radiosensitive tumor with the prognosis favorable in the stages A and B patients as treated by these three modalities. Two stage A patients are alive for more than 5 years. One of them was treated by radiotherapy alone, the other by combination of surgery and radiation. The third stage A patient as treated by radiotherapy alone has survived more than 3 years. One stage C patient, treated by combination of radiation and surgery, is still alive for more than 3 years. The other stage C patient, treated by radiotherapy alone, had survived for only 7 months after the treatment. The radiation dose varies with the extent of invasion. In stages A and B lesions, a dose of 4,500-5,500 rad in 5 weeks may be reasonable but in stage C, a dose of 6,000-6,500 rad in 7 weeks should be given. The authors agree to the prognostic equation proposed by Homzie et al. It may be possible to predict the tumor control or recurrence after a period of 3 years which gives an accuracy rate of 87%.

Adult↗

PubMed1983

Purification and characterization of two forms of a low-affinity Ca2+-ATPase from erythrocyte membranes.

A low-affinity Ca2+-ATPase from erythrocyte membranes has been purified by agarose suspension electrophoresis and polyacrylamide gel electrophoresis in the absence of detergents. For maximal activity a calcium concentration above 10 mM is required. The activity is independent of magnesium. The Km value for ATP is about 60 microM. The enzyme appears in two forms (A and B) with similar amino acid composition. The specific activity of A is higher than that of B. Gel electrophoresis in SDS of A gives a pattern consisting of two bands. B gives the same pattern; the only difference between the patterns is the ratio of the amounts of protein in the bands. The apparent molecular weight of the proteins in the two SDS bands has been estimated at 23000 and 21000, respectively. The results obtained can be explained by assuming that the two proteins corresponding to the two bands obtained in SDS electrophoresis have a similar structure and can associate to complexes A and B. We have also shown that electrophoretic and chromatographic supporting media can induce aggregation of (membrane) proteins. Artificial complexes can thus be formed and cause misinterpretation of the data obtained. This may be the reason why some authors have speculated that Ca2+-ATPase is active only in complex with other proteins such as spectrin and actin.

Adenosine Triphosphate↗

PubMedDate not supplied

A new method of deriving velocity and acceleration curves for height from the kernel estimation of distance.

Further development of the optimal kernel (OK) method of growth curve analysis of Gasser et al. (1984b) is presented with the aim of eliminating the necessity of repeated changes in bandwidth to suit different characteristics of the velocity and acceleration curves at varying ages. After using the OK method to obtain a distance curve for height, we introduce a new method (VADK) to derive velocity and acceleration curves from the fitted distance curve. The results from growth data on 16 boys and 15 girls from the Edinburgh Longitudinal Study are presented in a preliminary test of this method in comparison with the OK estimation.

Age Factors↗

PubMedDate not supplied

Growth during puberty in the XYY boy.

The availability of a cohort of eight unselected XYY boys identified by newborn cytogenetic screening has enabled their growth to be studied longitudinally in comparison with controls from the same population. While no difference had been found in dimensions at birth, increased height velocity in childhood resulted in the XYY boys being 7.6 cm taller at the onset of their pubertal growth spurt. Increased intensity of growth at puberty with a peak height velocity of 10.6 cm/year contributed to their adult height of 188.1 cm. XYY boys showed twice the male-female difference in height implying that genes on the Y chromosome exert a quantitative effect on the sexual dimorphism of growth.

Body Height↗

PubMedDate not supplied

The growth of XXX females: population-based studies.

Longitudinal measurements of height, sitting height and leg length are compared between 11 XXX girls identified by cytogenetic screening, and 16 chromosomally normal controls from the same population using a nonparametric method. While height velocity did not differ between the two groups either during the pubertal or the mid-childhood spurts, leg length velocity was significantly increased during the mid-childhood spurt, between 4 and 9 years of age. A further contribution to the increased leg length came from the slower decline in leg length velocity at the end of the pubertal spurt. The possible mechanisms involved in these changes are discussed.

Adolescent↗

PubMedDate not supplied

Epidemiological and genetic studies of myotonic dystrophy type 1 in Taiwan.

To investigate the prevalence and genetic characteristics of myotonic dystrophy type 1 (DM1) in Taiwan, DM-suspected patients and their families identified during the period of 1990-2001 had their clinical records reevaluated and the CTG repeat sizes at the DM1 locus examined. A total of 96 subjects belonging to 26 families were identified as DM1 patients, which gave a minimal disease prevalence of 0.46/100,000 inhabitants. Clinical anticipation was frequently observed in affected families, even in some parent-child pairs with transmission contraction of the CTG repeat size. The inverse correlation between age at onset and CTG repeat length was significant only in patients with small expansions. In addition, a DM1 carrier with a childhood-onset son was found to have CTG length heterogeneity in the range of 40-50, indicating that premutation alleles could be unstable during gametogenesis as well as in somatic tissues. Our data demonstrated that DM1 is a rare disease in Taiwan and showed that transmission contraction of repeat size is more likely to occur in alleles with large repeats.

Adolescent↗