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Biomedical subjects

H Ma

Publications and source records attributed to H Ma.

At least 253 records · Page 14Linked to original sources
PubMed1995

[Pathologic studies on preventive and therapeutic effects of the formic mixture on experimental silicosis].

In order to investigate the preventive and therapeutic effects of formic mixture on experimental silicosis, 96 Wistar rats were divided randomly into three groups, 1st group was taken as preventive administration (Two days before exposure to dust), 2nd group-therapeutic administration (one month after exposure to dust) and 3rd control group-model of silicosis. All above-mentioned animals were instilled intratracheally with standard quartz dust. At 1st, 3rd, 6th and 12th month after instillation of dust, rats from each group were sacrificed and pathohistologic studies were performed on their lung tissue. The results showed that the progressive degree of silicotic fibrosis in various groups were greatly different, i. e. 3rd group was severest, 2nd group medium, and 1st group was mildest. Either the differences of grade or quantity of fibrosis in lung tissue was significant between 1st and 3rd group, P < 0.01. The difference of the grade of fibrosis between 2nd and 3rd group was also significant, P < 0.05, but that between 1st and 2nd group was insignificant. The results demonstrated that administration of formic mixture, in particular, preventive administration, could inhibit greatly the process of silicotic fibrosis, and provided a basis for clinical application of this drug.

Animals↗
PubMed1995

Ultrastructural and radioautographic studies on DNA synthesis in Leydig cells on aging mouse testis.

A morphological observation and a radioautographic study were carried out to detect the ultrastructure and aging changes of DNA synthesis of the Leydig cells, whose structure has been observed and the area of the lipid droplets in the cytoplasm calculated. The observation by electron microscopy showed that Leydig cells contained abundant mitochondria and endoplasmic reticulum and that the area of the lipids in the cytoplasm changed with aging. Only little lipid droplets were found in embryonic and early postnatal stages, but they increased from postnatal two weeks onwards and no significant differences were found from 9 months to 21 months. The DNA synthesis in these cells was not vigorous at embryonic day 19, explored by light microscopic radioautography 1 hr. following a single injection of 3H-thymidine. The labeling index increased slightly before six months of age and reached its peak at 9 months. There was no significant difference found in the number of labelled cells from that time on. A relatively high level was maintained at adult and senescent periods. Our results demonstrate that the generation of the Leydig cells contained plentiful lipid droplets was vigorous at adult and senescence.

Aging↗
PubMed1994

Amino-terminal conserved region in proteinase inhibitor domain of calpastatin potentiates its calpain inhibitory activity by interacting with calmodulin-like domain of the proteinase.

Calpastatin is a widely distributed endogenous inhibitor protein specifically acting on calpain (Ca(2+)-dependent proteinase) and is known to interact with the calmodulin-like domain (CaMLD) of the proteinase in a Ca(2+)-dependent fashion. The calpastatin molecule consists of four inhibitory domains (domains 1-4) with mutually homologous sequences in three regions designated as A, B, and C. Acidic amphiphilic alpha-helical motifs are found in both regions A and C. We investigated the correlation between the calpain inhibition potency and the ability of calpastatin to bind to recombinant CaMLD of the mu-calpain large subunit using various mutant proteins of pig calpastatin domain 1 expressed in Escherichia coli. Substitution of conserved Leu-161 with Pro in region A caused a reduction in activity of both calpain inhibition and CaMLD binding. Additional substitution of Leu-236 with Pro in region C further decreased the calpain inhibitory activity and caused a loss of CaMLD binding ability. The effects of mutation in region C alone on the above activities were smaller than those in region A. Although a mutant of deletion in the entire region B had no calpain inhibitory activity, it retained the CaMLD binding ability. On the other hand, although a region B oligopeptide had a moderate inhibitory activity, it had no CaMLD binding ability. These results suggest that region A has a role in potentiating the inhibitory activity of calpastatin by interacting with CaMLD of calpain to form a tighter complex where region B exerts the inhibitory function.

Amino Acid Sequence↗
PubMed1994

Isolation of cDNAs encoding guanine nucleotide-binding protein beta-subunit homologues from maize (ZGB1) and Arabidopsis (AGB1).

We have isolated cDNAs from maize (ZGB1) and Arabidopsis (AGB1) encoding proteins homologous to beta subunits of guanine nucleotide-binding protein (G protein). The predicted ZGB1 and AGB1 gene products are 76% identical to each other and 41% or more identical to animal G protein beta subunits. Both predicted proteins contain seven repeats of the so-called "WD-40" motif, where WD is Trp-Asp. RNA blot analysis indicates that ZGB1 mRNA is present in the root, leaf, and tassel and that AGB1 mRNA is expressed in the root, leaf, and flower. DNA blot hybridizations indicate that maize and Arabidopsis genomes contain no other genes that are highly similar to ZGB1 and AGB1, respectively, suggesting that the newly isolated G protein beta-subunit homologues are likely to have unique functions. Furthermore, these G protein beta-subunit homologues are conserved among other plant species and may play important role(s) in plant signaling.

Amino Acid Sequence↗
PubMed1994

Analysis of calcium-dependent interaction between amino-terminal conserved region of calpastatin functional domain and calmodulin-like domain of mu-calpain large subunit.

Calpain requires Ca2+ both for proteolysis of its substrates and for interaction with its endogenous inhibitor, calpastatin. Although calmodulin-like domains (CaMLDs) of large and small subunits of calpain have been suggested to be the sites for Ca(2+)-dependent interaction with calpastatin, specificity and molecular basis of the interaction have remained unclear. We investigated the interaction between the CaMLD of human mu-calpain large subunit expressed in Escherichia coli and a 19-residue synthetic oligopeptide corresponding to the region A (the amino-terminal conserved acidic region) of one of the four repetitive functional domains of calpastatin. The recombinant CaMLD bound to the oligopeptide immobilized on Sepharose beads in a Ca(2+)-dependent manner. The CaMLD failed in binding to a mutant oligopeptide with one amino acid substitution. Enhancement of fluorescence intensity of a hydrophobic probe, 2-(p-toluidino)naphthalene-6-sulfonate, was observed upon incubating with the CaMLD and further increased by Ca2+. The Ca(2+)-dependent enhancement of fluorescence intensity was strongly suppressed by the wild type oligopeptide, but not by the mutant one. Kinetic experiments were performed with BIAcore where binding of the CaMLD to the oligopeptide immobilized on a biosensor chip was detected as real time signals of surface plasmon resonance. The determined dissociation constant (KD) was 3.1 x 10(-9) M. These results suggest that the region A of calpastatin binds to the CaMLD in a specific manner similar to interactions between calmodulin-binding peptides and calmodulin where hydrophobic properties are known to be important.

Amino Acid Sequence↗
PubMed1994

Spatially and temporally regulated expression of the MADS-box gene AGL2 in wild-type and mutant arabidopsis flowers.

AGL2 is one of several Arabidopsis floral MADS-box genes that were isolated based on sequence similarity to the homeotic gene AGAMOUS. To investigate its possible role in flower development, we have characterized in detail the expression pattern of AGL2 in both wild-type and mutant flowers using RNA in situ hybridization. We find that AGL2 is floral-specific; it is not expressed in the inflorescence meristem. Within the floral meristem, AGL2 is first expressed very early in development, after the floral meristem has emerged from the inflorescence meristem but before any of the organ primordia emerge. The AGL2 transcript is very abundant and uniform throughout the floral meristem and in the primordia of all four floral organs: sepals, petals, stamens and carpels. Thus, AGL2 represents a new class of MADS-box genes which is expressed in all four whorls of the flower. The AGL2 transcript remains abundant in each organ during morphological differentiation, but diminishes as each organ undergoes the final maturation phase of development. AGL2 expression is high in developing ovules and, after fertilization, in developing embryos and seed coats, abating as seeds mature. In the floral organ identity mutants ag-1, ap3-3 and ap2-2, the AGL2 expression pattern is organ- and stage-dependent. These results indicate that AGL2 may play a fundamental role in the development of all floral organs, and of seeds and embryos, and that AGL2 ultimately depends upon the organ identity genes for proper expression.

Alleles↗
PubMed1994

GTP-binding proteins in plants: new members of an old family.

Regulatory guanine nucleotide-binding proteins (G proteins) have been studied extensively in animal and microbial organisms, and they are divided into the heterotrimeric and the small (monomeric) classes. Heterotrimeric G proteins are known to mediate signal responses in a variety of pathways in animals and simple eukaryotes, while small G proteins perform diverse functions including signal transduction, secretion, and regulation of cytoskeleton. In recent years, biochemical analyses have produced a large amount of information on the presence and possible functions of G proteins in plants. Further, molecular cloning has clearly demonstrated that plants have both heterotrimeric and small G proteins. Although the functions of the plant heterotrimeric G proteins are yet to be determined, expression analysis of an Arabidopsis G alpha protein suggests that it may be involved in the regulation of cell division and differentiation. In contrast to the very few genes cloned thus far that encode heterotrimeric G proteins in plants, a large number of small G proteins have been identified by molecular cloning from various plants. In addition, several plant small G proteins have been shown to be functional homologues of their counterparts in animals and yeasts. Future studies using a number of approaches are likely to yield insights into the role plant G proteins play.

Animals↗
PubMed1994

Identification of a homeobox-containing gene with enhanced expression during soybean (Glycine max L.) somatic embryo development.

Homeotic gene are key 'switches' that control developmental processes. Homeotic genes containing the consensus 'homeobox' domain have been identified from a number of organisms including Drosophila melanogaster, Caenorhabditis elegans, Homo sapiens, and Zea mays. Although homeotic genes have been demonstrated to be important in embryo development of some insects, amphibians, and mammals, there are no reports of their involvement in plant embryogenesis. Here, we report the isolation and characterization of a cDNA clone for a homeobox-containing gene expressed in somatic embryos of soybean. The cDNA (Sbh1 for soybean homeobox-containing gene) was isolated using maize Knotted-1 (Kn1) cDNA as a heterologous probe. The Sbh1 cDNA clone is 1515 bp long which is the approximate size of its transcript. Within the homeodomain, the amino acid sequence of a helix-turn-helix structure, and invariant and conserved residues were identified. The deduced SBH1 protein shares a high amino acid identity with KN1 protein (47.0% overall and 87.5% for the homeodomain). Southern hybridization analysis indicated that Sbh1 is a member of a small gene family. The expression of Sbh1 is development- and tissue-specific. The transcript of Sbh1 was present in early-stage somatic embryos, increased prior to cotyledon formation and decreased thereafter. Sbh1 was weakly expressed in soybean stems and hypocotyl but was not detected in other plant tissues and nonembryogenic materials. The enhanced expression during embryogenesis, the homology with maize Kn1 gene, and the regulatory nature of homeodomain proteins suggest that the SBH1 protein plays an important role in plant embryo development.

Amino Acid Sequence↗
PubMed1994

Adenosine receptor-mediated inhibition of cardiac adenylyl cyclase activity may involve multiple receptor subtypes.

We previously reported that the adenosine receptor agonist N6-phenylisopropyladenosine (R-PIA) inhibits adenylyl cyclase in detergent-permeabilized embryonic chick ventricular myocytes in the presence of the adrenergic receptor agonist, isoproterenol (Ma and Green 1992). The slope of the dose response curve of this inhibition is very shallow (nH 0.3-0.4). The present studies on detergent-permeabilized chick myocytes evaluate the mechanisms underlying this shallow inhibition curve. We find that in contrast to R-PIA, two additional adenosine receptor agonists, N6-cyclopentyladenosine (CPA) and 2-chloro-N6-cyclopentyladenosine (CCPA), inhibit cardiac adenylyl cyclase activity in a monophasic, dose-dependent manner (nH approximately 1). Two A1 adenosine receptor antagonists, 8-cyclopentyl-1,3,-dipropylxanthine (CPX) and 3-(4-amino)phenethyl-1-propyl-8-cyclopentylxanthine (BW-A884U) affect the R-PIA responses differently. BW-A884U shifts the R-PIA dose response curve to the right in a parallel fashion while CPX both shifts the R-PIA response curve and increases its steepness. Cardiac A1 adenosine receptors were further characterized using one antagonist ([3H]CPX) and two agonist ([3H]R-PIA and [3H]CCPA) radioligands. [3H]CPX binds to the adenosine receptors in detergent-permeabilized ventricular myocytes with a Kd value of 3.3 +/- 0.2 nM and a BMAX value of 30.1 +/- 2.4 fmol/mg protein (means +/- SEM; N = 4). [3H]R-PIA detects more sites than [3H]CCPA (22.8 +/- 4.0 and 8.3 +/- 1.3 fmol/mg protein, respectively; GTP-free conditions). CPA and CCPA inhibit [3H]R-PIA binding in a shallow, dose-dependent manner (nH approximately 0.4), while R-PIA and CPA inhibit [3H]CCPA binding with a nH approximately 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclase Inhibitors↗
PubMed1994

Equity and the utilization of health services: report of an eight-province survey in China.

This paper investigates equity with respect to one component of welfare in China--the provision and use of health services. Based upon a large-scale survey of almost 16,000 individuals in eight provinces in China, we examine a sub-sample of working-age adults who have identified themselves as injured or ill during the four weeks prior to being interviewed. We found that, beyond the level of severity of the reported condition, very few individual-level factors are related to the use of services when ill or injured. Only gender (female) and employment in state-run enterprises are associated with higher patterns of use. These results suggest that China has achieved a very wide distribution of clinics and other services at the local level, and that they are widely used by those who identify need for them. It is rare to be over half an hour away by bike from some form of care and the majority of care appears to be reasonably inexpensive. This broad availability of services contrasts with recent reports from China stressing declining accessibility, and paints a picture of relatively equal access to health care.

Adult↗
PubMed1994

Cloning and analysis of a gene cluster from Streptomyces coelicolor that causes accelerated aerial mycelium formation in Streptomyces lividans.

We describe the cloning and analysis of two overlapping DNA fragments from Streptomyces coelicolor that cause aerial mycelium to appear more rapidly than usual when introduced into Streptomyces lividans on a low-copy-number plasmid vector. Colonies of S. lividans TK64 harboring either clone produce visible aerial mycelia after only 48 h of growth, rather than the usual 72 to 96 h. From deletion and sequence analysis, this rapid aerial mycelium (Ram) phenotype appears to be due to a cluster of three genes that we have designated ramA, ramB, and ramR. Both ramA and ramB potentially encode 65-kDa proteins with homology to ATP-dependent membrane-translocating proteins. A chromosomal ramB disruption mutant of S. lividans was found to be severely defective in aerial mycelium formation. ramR could encode a 21-kDa protein with significant homology to the UhpA subset of bacterial two-component response regulator proteins. The overall organization and potential proteins encoded by the cloned DNA suggest that this is the S. coelicolor homolog of the amf gene cluster that has been shown to be important for aerial mycelium formation in Streptomyces griseus. However, despite the fact that the two regions probably have identical functions, there is relatively poor homology between the two gene clusters at the DNA sequence level.

ATP-Binding Cassette Transporters↗
PubMed1994

The body mass index of Chinese adults in the 1980s.

Patterns and trends in the body composition of Chinese adults are studied with data from the 1982 China Nationwide Nutrition Survey (CNS-82) and the 1989 China Health and Nutrition Survey (CHNS-89). The CNS-82 showed rural inhabitants were approximately 3 kg lighter than urban residents and approximately 2.2 cm shorter. Males were heavier (55.2 +/- 7.4 vs 50.7 +/- 8.0 kg) and taller (165.3 +/- 7.3 and 153.5 +/- 6.3 cm). Using a cut-off for underweight of a body mass index (BMI: kg/m2) < 18.5 and for obesity of > 25, 11.6% and 12.9% of the urban and rural sample were underweight and 9.8% and 6.9% respectively were overweight. The CHNS-89 surveyed 5138 adults aged 20-45 in eight selected provinces. The proportion of underweight in both urban and rural samples declined slightly (approximately 1.3%) but the proportion of obesity increased considerably (4.8% for the urban sample and 2% for the rural one). Increased income was significantly associated with reduced low body mass index (BMI: kg/m2) in the urban sample while, for the rural and overall samples, the opposite was found for obesity. Provincial patterns in energy intake were not associated with the distribution of BMI while occupation was. In particular, government officials and housewives were much more likely to be obese as also were subpopulation groups consuming greater proportions of energy from animal sources. Over 80% of the population fell in the normal BMI range (18.5-25). This may relate to the relatively even distribution of food in China during the past several decades.

Adult↗
PubMed1994

[Long-term effect of the modified type-III tympanoplasty].

Tympanoplasty using reconstructed ossicular chain from auto and foreign rib cartilages were performed on 264 ears with missing malleus. The postoperative follow-ups have been made in 102 ears with auto cartilage for 5-6 years and in 162 ears with foreign cartilage more than 4 years. The hearing level of 79 ears in the former (77.4%) and 124 ears in the latter (76.5%) have been enhanced by 15 dB or to applied hearing level. Long-term hearing improvement was satisfactory. The characteristics of the surgical methods was discussed.

Adolescent↗
PubMed1994

Radioautographic study of benidipine hydrochloride. Localization in the mesenteric artery of spontaneously hypertensive rat.

Microradioautographic study of [3H]-benidipine hydrochloride (KW-3049, CAS 91599-74-5) and nitrendipine (CAS 39562-70-4) localization was performed in the supramesenteric arteries of the spontaneously hypertensive rats (SHR) at 10 and 30 min after intravenous administration or in vitro incubation. The distribution of silver grains was observed by light and electron microscopy and the number of grains was counted in the tunicae intima, media and adventitia of the arteries. Areas of the correlated part of the artery were measured and the grain count per area was calculated. The grain count of [3H]-benidipine hydrochloride showed almost uniform distribution in the tunicae intima and media, which was compared at 10 and 30 min after the administration both in the in vivo and in the in vitro studies. The grain density of [3H]-nitrendipine to the tunicae intima and media increased time-dependently. Electron microscopic observation revealed that the fine distribution of [3H]-benidipine hydrochloride was mainly localized on the plasma membrane and on the cytoplasm of the cellular components of the mesenteric artery. The result suggested that the distribution of [3H]-benidipine hydrochloride was related to its pharmacologically active site, i.e. plasma membrane of the tunica intima and the smooth muscle cells of the tunica media.

Animals↗
PubMed1993

Isolation and characterization of the binding sequences for the product of the Arabidopsis floral homeotic gene AGAMOUS.

The Arabidopsis floral homeotic gene AGAMOUS (AG) is required for normal flower development. The deduced AG protein contains a region which shares substantial sequence similarity with the DNA-binding domains of known transcription factors, SRF (human) and MCM1 (yeast). Therefore, it is likely that AG is also a DNA-binding protein regulating transcription of floral genes. We describe here several experiments to characterize AG-DNA binding in vitro. We show that AG indeed binds a DNA sequence matching the consensus of SRF targets. Further, we have selected the AG-binding sequences from a pool of random oligonucleotides, and deduced an AG-binding consensus sequence of TT(A/T)CC(A/T)(A/t)2(T/A)NNGG(-G)(A/t)2. We have demonstrated that AG binds to the consensus region of three of the oligonucleotides by footprinting analysis. Finally, we have examined AG's relative binding affinity for different sequences, as compared to SRF, by gel mobility shift analysis. Our results indicate that AG is a sequence-specific DNA-binding protein, and that the AG-binding consensus sequence is similar to those of MCM1 and SRF.

AGAMOUS Protein, Arabidopsis↗