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Biomedical subjects

L Gao

Publications and source records attributed to L Gao.

At least 235 records · Page 13Linked to original sources
PubMed1991

Myosin expression in hypertrophied fast twitch and slow tonic muscles of normal and dystrophic chickens.

Disruption of the development program of myosin gene expression has been reported in chicken muscular dystrophy. In the present report, the relationship between muscular dystrophy and the ability of muscle to respond to an increased work load with a transition in the myosin phenotype has been investigated. Hypertrophy of slow tonic anterior latissimus dorsi (ALD) and fast twitch patagialis (PAT) muscles was induced by overloading for 35 days and myosin expression was analyzed by electrophoresis and immunocytochemistry. Normal and dystrophic chicken ALD muscles have nearly identical proportions of SM-1 and SM-2 isomyosins and both exhibit an age-related repression of the SM-1 isomyosin which is enhanced and accelerated by overloading. Immunocytochemistry with anti-myosin heavy chain (MHC) antibodies demonstrates the appearance of nascent myofibers in overloaded ALD muscles from both normal and dystrophic chickens. A minor fast twitch fiber population is also identified which doubles in number with overloading in normal ALD muscles. There are only half as many fast twitch fibers in control dystrophic ALD muscles and this number does not increase with overloading. In contrast to ALD muscles, the isomyosin profile of normal and dystrophic PAT muscles is quite different. There is significantly more FM-3 and significantly less FM-1 isomyosin in the dystrophic PAT muscle. However, both normal and dystrophic PAT muscles exhibit an overload-induced accumulation of the FM-3 isomyosin. Immunocytochemistry reveals that, unlike the normal PAT muscle, the dystrophic PAT muscle contains a population of myofibers which express slow MHCs. As in the ALD muscle, overload-induced hypertrophy is associated with a repression of the SM-1 MHC in these fibers. Nascent myofiber formation does not occur in either normal or dystrophic overloaded PAT muscles.

Animals↗
PubMed1991

The modification of an already-programmed response: a new interpretation of Henry and Harrison (1961).

In an influential study, Henry and Harrison (1961) examined the capability of subjects to inhibit an already-programmed response. Their experiment showed that when a stop signal was presented only 100 ms after the imperative go signal; a subject could not inhibit the movement. The inferences were that rapid ballistic actions are programmed and the program cannot be altered in a limited amount of time (see Schmidt, 1988). In the present note, we describe some forgotten data from the Henry and Harrison paper and, with a trend analysis, demonstrate that the stop signal does have an influence on the movement in a somewhat continuous fashion.

Journal Article↗
PubMed1991

Effect of fathers' age and birth order on occurrence of congenital heart disease.

STUDY OBJECTIVE: The aim was to examine if there is an effect of fathers' age and of birth order on the occurrence of congenital heart disease. DESIGN: This was a hospital based case-referent study including use of birth defects surveillance data. SUBJECTS: Subjects were 497 cases of congenital heart disease aged between 3 months and 5 years, born in Beijing and Hebei Province, China; 6222 children without congenital heart disease serve as reference baseline. MEASUREMENTS AND MAIN RESULTS: With stratified analysis and logistic regression analyses, congenital heart disease was found to be associated with fathers' age less than 25 years (odds ratio 2.63), independent of mothers' age and of birth order. There was also evidence to show a higher birth order effect on the occurrence of congenital heart disease independent of parental ages. CONCLUSION: Higher birth order and fathers aged less than 25 years were both independently associated with some categories of congenital heart disease and with congenital heart disease overall.

Birth Order↗
PubMed1991

Isolation and molecular cloning of insulin-like growth factor-binding protein-6.

Insulin-like growth factors (IGFs) together with their binding proteins (BPs) are potential regulators of folliculogenesis in mammalian ovary. To identify the various species of IGFBPs present in the ovary, we have undertaken a comprehensive purification scheme using gel filtration, ligand-affinity chromatography, and several steps of reverse phase HPLC to isolate all of the BPs in pig ovarian follicular fluid. Our effort yielded five distinct IGFBPs, and upon analysis, they were found to correspond to the previously identified human and rat IGFBP-2, -3, -4, -5, and -6. IGFBP-1 was not found in the pig ovarian follicular fluid under our experimental procedure. Of the six known classes of IGFBPs, the complete primary structures of the first five have been determined, but not IGFBP-6. Using amino acid sequence information from a tryptic fragment of pig IGFBP-6 to prepare a probe, cDNA clones encoding rat and human IGFBP-6 have been isolated and characterized. The deduced amino acid sequence revealed that rat IGFBP-6 contains 201 amino acids with a calculated mol wt of 21,461, while the human homolog contains 216 amino acids with a calculated mol wt of 22,847. In addition, a distinctive feature of human and rat IGFBP-6 is that they lack, respectively, two and four of the 18 homologous cysteines that are present in all other five IGFBPs. The missing cysteines in IGFBP-6 resulted in the absence of the invariant Gly-Cys-Gly-Cys-Cys sequence in the amino-terminal region of the molecule. Human IGFBP-6 possesses a single Asn-linked glycosylation site near the carboxyl-terminal, whereas no potential Asn-linked glycosylation sites are present in the rat sequence. A single 1.3-kilobase IGFBP-6 mRNA was detected by Northern analysis in all rat tissues examined, including testis, intestine, adrenal, kidney, stomach, spleen, heart, lung, brain, and liver, indicating that this BP is a ubiquitous protein. The chromosome location of the IGFBP-6 gene in human has been determined using polymerase chain reaction on somatic cell hybrid DNAs of human and hamster, and the results showed that it is located on chromosome 12.

Amino Acid Sequence↗
PubMed1991

[Study on the adequate dosage of vitamin A in the prevention and treatment of postburn visceral injury].

In this study, we observed the influence of various doses of vitamin A on the serum and liver vitamin A levels and the effect of prevention and treatment on the injured thymus, spleen, liver and mucosa of the small intestine after 20% BSA III degree burn in the rat. The results showed that not only the serum and liver vitamin A contents were lower in the rats (burned group I) receiving vitamin A 6 micrograms/100 gb. w./d. as compared to the uninjured control, but also the thymus was significantly atrophic, especially with decrease of T-cell. The spleen was swollen, and the corpuscles and karyokinesis of the cell decreased. The nucleoli margination and double-nucleus in hepatocytes were also decreased significantly. The small intestine villi were atrophic and the mucosa became thinner. In the postburn rats receiving vitamin A 25 micrograms/100 gb. w./d. (burned group II), the above-mentioned changes were not different as compared with the uninjured controls. In those receiving vitamin A 50 or 100 micrograms/100 gb. w./d. (burned group II and IV), the effect of prevention and treatment of postburn lesions was not superior to those of group II. So it can be seen that the adequate dosage of supplementation of vitamin A in the postburn rats was about 25 micrograms/100 gb. w./d., i.e. 4 times the normal requirement of the rat.

Animals↗
PubMed1988

Defective cell mediated immunity in sarcoidosis: effect of interleukin-2.

Interleukin-2 has been reported to enhance the immune response in diseases characterised by defective cell mediated immunity. The effect of exogenous recombinant interleukin-2 was studied on the proliferative and cytotoxic responses of peripheral blood mononuclear cells from 39 patients with sarcoidosis and 14 healthy control subjects. The proliferative response to purified protein derivative was smaller in patients than in control subjects (p less than 0.001) whereas the response to 80 U interleukin-2 alone and to purified protein derivative and interleukin-2 did not differ significantly between the two groups. In addition, in eight patients but no control subjects tritiated thymidine incorporation induced by the combination of purified protein derivative and interleukin-2 was more than twice the sum of that induced by purified protein derivative and interleukin separately. Cytotoxic activity occurring spontaneously and induced by purified protein derivative and interleukin-2 in blood mononuclear cells was significantly less for patients with sarcoidosis than for control subjects (p less than 0.05 spontaneous, less than 0.001 purified protein derivative induced, less than 0.02 interleukin induced). Synergism between antigen and interleukin did not occur with respect to the cytotoxic response in either patients or controls. Defective interleukin-2 production may contribute to, but does not entirely explain, the functional abnormalities of peripheral blood lymphocytes from patients with sarcoidosis.

Adult↗