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Biomedical subjects

H Jiang

Publications and source records attributed to H Jiang.

At least 541 records · Page 30Linked to original sources
PubMed1995

A comparison of spinal ligaments--differences between bipeds and quadrupeds.

Following dissection, the spinal ligaments were observed in a selection of bipedal, pseudobipedal and quadrupedal animals during a search for an appropriate animal model for investigating the innervation of these ligaments. Midline spinal ligaments were found in all animals while lateral spinal ligaments could only be observed in bipedal (human) and pseudobipedal (avian) species. The presence of lateral spinal ligaments in these animals and their absence in quadrupeds suggests that the development of the lateral ligaments reflects a mechanical challenge unique to the erect spine and that these lateral spinal ligaments are fundamental to the stability of an erect posture.

Animals↗
PubMed1995

One-stage microneurovascular free abductor hallucis muscle transplantation for reanimation of facial paralysis.

We introduce a new method using abductor hallucis muscle free transplantation for reanimation of the cheek with long-standing facial palsy in six young patients. The muscle is used to reanimate facial palsy because it has many unique advantages: (1) appropriate size and shape of the muscle and adequate bulk, (2) closely parallel alignment and unvaried anatomy of the main vessels and nerve distribution to the muscle, (3) a long neurovascular pedicle, (4) easy surgical isolation of the muscle and its neurovascular pedicle, and (5) no functional deficit after muscle removal. The nerve and muscle grafts can be performed by microneurovascular anastomosis in one surgical procedure. The follow-up period was over 1 year. A satisfactory result was obtained in five of six patients.

Adult↗
PubMed1995

[Dynamics of blood lead level in exposed workers and its effects on fetal constitutional development].

Levels of blood lead (Pb-B) and zinc protoporphyrin (ZPP) in exposed women of a storage battery plant during their early gestation and delivery stage were determined and compared with those in control women. Pb-B in exposed women kept in a consistently high level of 0.98 mumol/L and ZPP of 1.35 mumol/L. Pb-B level in umbilical cord of their neonates reached 0.90 mumol/L and ZPP 1.11 mumol/L, both of which were significantly higher than those in control women (0.26 mumol/L and 0.34 mumol/L of Pb-B and 0.51 mumol/L and 0.78 mumol/L of ZPP in women's blood and umbilical cord blood, respectively). The significance of consistent increase in Pb-B and ZPP and their effects on fetal development were discussed in the paper.

Embryonic and Fetal Development↗
PubMed1995

Modulation of limb bud chondrogenesis by retinoic acid and retinoic acid receptors.

An excess of retinoic acid (RA) in the mouse embryo in utero produces hypochondrogenesis and severe limb bone deformities. Since one of the RA receptors--RAR-beta 2, is specifically induced in the limb bud cells upon treatment of embryos with teratogenic doses of RA, we investigated if this receptor played a role in teratogenesis by regulating the process of chondrogenesis. In micromass cultures of mouse limb bud mesenchymal cells, we found that a downregulation of RAR-beta 2 as well as several other RAR isoforms by supplementation of the culture medium with specific oligodeoxynucleotides stimulated chondrogenesis: cartilage nodule number, sulfated proteoglycans, and synthesis of collagen type IIB were all enhanced in a dose-dependent manner. However, only the antisense RAR-beta 2 probe efficiently prevented the strong inhibitory effects of exogenous RA on chondrogenesis in these cells. The data suggest that the RAR-RA complexes play a role in position-dependent patterning of the limb skeleton in normal development and that, in particular, RAR-beta 2 serves to prevent the mesenchymal cells from expressing their chondrogenic bias. Our results further strengthen the argument that RA-dependent elevation in RAR-beta 2 levels plays a unique role in RA-induced teratogenesis.

Animals↗
PubMed1995

[The mechanism for splenic promoting effects on liver cirrhosis].

The model of liver cirrhosis was induced by CCl4 and alcohol in rats, which were subjected to splenectomy or given Tuftsin. The isolated and purified liver parenchymal, Kupffer and Ito cells were cultured with CCl4 and splenic conditional fluid or Tuftsin. The RNA isolated from the liver tissues of cirrhosis animals were hybridized with five kinds of cDNA probes. In this study we explored the mechanism of spleen's promoting effects on the liver cirrhosis formation at the whole body, cellular and molecular levels. The result showed that in cirrhosis model, the levels of IL1, IL6 and TNF alpha in serum of rats in imitative splenectomy or Tuftsin group were significantly increased compared to those in splenectomy group (P < 0.05). Cell culture showed that if medium contained CCl4 and splenic conditional fluid or Tuftsin, its cells can secrete more fibronectin, laminin and collagen I than those cultured in medium only contained CCl4 (P < 0.05). Slot blot hybridization showed that the RNA isolated from liver of rats in imitative splenectomy or Tuftsin group hybridized with probes of TNF alpha, IL1 beta, TGF beta and Collagen I had a more high density picture of X-ray than that isolated from liver of rats in the splenectomy group. Should be it a complex process for spleen to promote liver cirrhosis formation, in which the TGF beta gene expression enhancement may be the key of splenic effects on liver fibrosis.

Animals↗
PubMed1994

Quantitative morphology of the lateral ligaments of the spine. Assessment of their importance in maintaining lateral stability.

STUDY DESIGN: This study used human cadaveric material to examine the three-dimensional morphology and biomechanics of the superior and lateral costotransverse ligaments and the intertransverse ligament of the spine. OBJECTIVES: To provide descriptive and quantitative data on the morphology of the lateral ligaments of the spine and to assess their importance in maintaining lateral stability, especially regarding the pathogenesis of idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Ligaments have been reported as being able to stabilize the spine by mechanical constraint and by neurologic feed-back. Midline spinal ligaments have been well studied but do not appear to be effective in maintaining lateral stability because of their sites of attachment. Lateral ligaments of the spine have not been adequately documented in the literature. METHODS: The morphology, sites of attachment, and dimensions of the superior costotransverse ligament, lateral costotransverse ligament, and intertransverse ligament from thoracic level 7 to thoracic level 10 were determined on 32 human cadavers. RESULTS: The intertransverse ligament was found not to be a true ligament. The lateral costotransverse ligament was a true ligament but did not have the characteristics appropriate for involvement in lateral stability. The superior costotransverse ligament also was a true ligament and had all of the characteristics appropriate for involvement in the active lateral balancing of the spine. CONCLUSIONS: In contrast to the midline ligaments of the spine, the superior costotransverse ligament perhaps is the most important ligament for active lateral balancing of the spine and warrants further study, particularly regarding the development of idiopathic scoliosis.

Aged↗
PubMed1994

Inhibition of anthralin-caused skin tumor promotion and interleukin-1 alpha production by potent immunosuppressant FK506.

The effect of FK506, a potent immunosuppressive agent, on 7,12-dimethylbenz[alpha]anthracene-initiated and anthralin-promoted skin tumor formation was examined in CD-1 mice. A topical application of 0.1 mumol FK506 to mouse skin 15 min prior to each anthralin treatment markedly inhibited skin tumor formation. Anthralin stimulated IL-1 alpha production in primary cultured mouse epidermal cells, and the peak IL-1 alpha level was observed at 6 h after the stimulation. Anthralin also stimulated IL-1 alpha release into culture medium. Both production and release of Il-1 alpha were markedly inhibited by FK506 (0.1 or 1 microM). FK506 (1 microM) alone neither affected IL-1 alpha production nor its release. It may be possible that the inhibition of IL-1 alpha production by FK506 is related to its anti-tumor-promoting action.

Administration, Topical↗
PubMed1994

Calcium and smooth muscle contraction.

The fact that smooth muscle exists in almost every hollow organ and is involved in a large number of disease states has led to a vast increase in smooth muscle research, covering areas from testing response to antagonists and agonists to measuring the molecular force generated by a single actin filament. Yet, the exact mechanisms regulating contractile response of smooth muscle remain unsolved. Calcium has been a central player in mediating smooth muscle contraction through binding with calmodulin, although there is evidence showing that under special circumstances smooth muscle can contract without change in intracellular Ca2+. In addition to the major regulatory pathway of Ca(2+)-calmodulin-myosin light chain kinase, there are other thin filament linked regulatory mechanisms in which Ca(2+)-calmodulin dependent phosphorylation of calponin and caldesmon may be involved. Ca2+ sensitivity of smooth muscle contraction may vary under different situations and this has recently been recognized as an important regulatory mechanism. Examples are protein kinase C (PKC) dependent phosphorylation of myosin light chain kinase which results in partial inhibition of contraction, and activation of myosin light chain phosphatase. There is new evidence showing that not only does Ca2+ regulate contraction by regulating the interaction of contractile proteins in smooth muscle, but also that shortening of smooth muscle itself reduces intracellular Ca2+ concentration, via a negative feedback.

Actins↗
PubMed1994

beta-Amyloid activates complement by binding to a specific region of the collagen-like domain of the C1q A chain.

beta-amyloid peptides that accumulate within the brain of individuals with Alzheimer's disease bind to C1q and activate the classical C pathway via a specific interaction with a site within the collagen-like domain of C1q (C1q-CLF). Synthetic analogues of beta-amyloid peptides, beta 1-42 and beta 1-40, bound to C1q and were strong activators of C as assessed by both total C consumption and C4 consumption. beta 1-42 was significantly more effective than beta 1-40 in binding to C1q and triggering C activation, whereas beta 1-28 demonstrated little or no binding or C activation. This C-activating capacity seems to be largely correlated with the assembly of the beta 1-42 into low speed sedimentable aggregates and/or macromolecular fibrils. Radiolabeled C1q and C1q-CLF bind specifically to these aggregates or amyloid fibrils. In addition, using synthetic C1q peptides in a solid phase binding assay, the major binding site of beta 1-42 to C1q was localized to the C1q A chain collagen-like residues 14-26, a region previously described as a novel interaction site for Ab-independent activators of C1. C1q A chain peptide 14-26 blocked the ability of beta-amyloid peptides to activate the classical C pathway, providing evidence that this relatively unrecognized mechanism of C activation (via binding to the C1q-CLF) may have crucial physiologic consequences. Finally, these observations provide further support for the hypothesis that C activation and inflammation may be a component in the pathogenesis of AD and suggest possibilities for modulating the progression of AD.

Alzheimer Disease↗
PubMed1994

Activation of phospholipase C beta 4 by heterotrimeric GTP-binding proteins.

Transient transfection assays were used to determine how the activity of phospholipase C beta 4, which is preferentially expressed in retina, was regulated. An expression vector carrying the full-length cDNA corresponding to phospholipase C beta 4 was constructed and co-transfected into COS-7 cells together with cDNA encoding the alpha subunits of the Gq class and various beta and gamma subunits corresponding to the heterotrimeric GTP-binding proteins. We found that all the alpha subunits of the Gq class, including G alpha q, G alpha 11, G alpha 14, G alpha 15, and G alpha 16 could activate PLC beta 4 and that none of the G beta gamma subunits that we tested including G beta 1 gamma 1, G beta 1 gamma 2, G beta 1 gamma 3, or G beta 2 gamma 2 activated phospholipase C beta 4. In control experiments, cotransfection with cDNA encoding the alpha subunit of transducin or Gi2 gave no activation of PLC beta 4. These results indicate that phospholipase C beta 4 is activated by G alpha subunits that are members of the Gq class, and, like the phospholipase C beta 1 isoform, it is refractory to activation in the transfection assay by many of the combinations of beta and gamma subunits found in the heterotrimeric G-proteins.

Amino Acid Sequence↗
PubMed1994

Mutually exclusive exon use and reactive center diversity in insect serpins.

We have isolated 38 cDNA clones for serpins from a lepidopteran insect, Manduca sexta, and have found that they are identical in sequence, except for a region encoding the carboxyl-terminal 40-45 residues, which includes the reactive center. Among these clones, there are 11 variants of the reactive center region, each encoded by a different version of the ninth exon in the serpin gene. Thus, evolution of this insect serpin gene has resulted from duplication and sequence divergence of only the exon encoding the reactive site. Alternative pre-mRNA splicing then generates inhibitor diversity and the potential to regulate a variety of proteinases, using the same protein framework joined to different reactive site region cassettes.

Alternative Splicing↗
PubMed1994

Teratogenesis by retinoic acid analogs positively correlates with elevation of retinoic acid receptor-beta 2 mRNA levels in treated embryos.

Retinoic acid (RA) plays an important role during normal embryogenesis, however high doses of RA are teratogenic. Retinoic acid receptor-beta 2 (RAR-beta 2) mRNA and protein levels were previously demonstrated to undergo rapid elevation in susceptible tissues after treatment with teratogenic doses of RA. In this report we compared the effects of a number of retinoids, which represent a wide variety of chemical structures and which differ in their teratogenic potencies, on RAR-beta 2 mRNA levels in mouse embryos 6 hr after treatment. Retinoid treatments which result in a high incidence of limb defects elevated RAR-beta 2 mRNA levels similarly (10-14 fold in the limb buds, 4-8 fold in the head, and 2-4 fold in the remainder of the body). On the other hand, retinoid treatments which cause a low or no incidence of limb defects resulted in minor changes in RAR-beta 2 mRNA levels in each embryonic region. Therefore, a strong positive correlation was found between the elevation of RAR-beta 2 mRNA levels and the retinoids which produce limb defects. This provides further evidence that an elevation of RAR-beta 2 mRNA levels, and subsequently protein levels, is an important event involved in mediating the effects of RA during dysmorphogenesis.

Abnormalities, Drug-Induced↗
PubMed1994

Differences in nigral neuron number and sensitivity to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in C57/bl and CD-1 mice.

The present study demonstrates that the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes significantly greater reductions in striatal dopamine levels in C57/bl mice than in CD-1 mice, thus confirming a greater sensitivity of the C57/bl mice to MPTP. To determine the possible reasons for this difference in MPTP sensitivity between these two mouse strains, we have compared both the organization and the number of substantia nigra (SN) neurons, the primary target of MPTP, in C57/bl and in CD-1 mice using immunostaining for tyrosine hydroxylase (TH) and calbindin-D28k (calbindin). In saline-injected animals, there is a significantly lower number of SN TH-positive and calbindin-positive neurons in C57/bl than CD-1 mice; no significant differences in the numbers of these neurons are found in the ventral tegmental area between the two strains. In MPTP-injected animals, the reductions in SN TH-positive neurons are significantly greater in C57/bl than in CD-1 mice. In contrast, MPTP does not cause any significant changes in the numbers of SN calbindin-positive neurons in either strain. The present study shows that C57/bl mice which have fewer SN TH-positive neurons are more sensitive to MPTP-induced toxicity than CD-1 mice. This observation suggests a possible inverse relationship between SN TH-positive neuron number and MPTP sensitivity. If correct, this hypothesis may be of major importance for Parkinson's disease since it is suggested that individuals at risk of developing this neurodegenerative disorder may have lower numbers of SN TH-positive neurons to start with. The present study also shows that SN calbindin-positive neurons are spared following MPTP administration. However, the observed difference in SN calbindin-positive neuron numbers does not account for the differential sensitivity to MPTP between these two mouse strains.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

Simultaneous and interleaved multinuclear chemical-shift imaging, a method for concurrent, localized spectroscopy.

A method is proposed for carrying out chemical-shift imaging simultaneously on several nuclei (1H and 31P in this example), using a commercial clinical NMR imager fitted with a second RF channel and a dual-tuned birdcage coil to fit the human head. Nuclei of different gamma are examined at the same field of view by exciting each nucleus successively at times proportional to gamma during the same phase-encoding gradient waveform. Thus, each higher-gamma nucleus is exposed to a smaller area of the gradient. Additionally, since in vivo protons typically have a shorter T1 and roughly an order of magnitude higher sensitivity than phosphorus, it is possible to interleave 1H-only acquisitions between the simultaneous 1H, 31P observations while the lower-gamma nucleus relaxes. Consequently, additional information is obtained with either higher spatial resolution or greater sensitivity (more signal averaging) without lengthening the duration of the examination.

Computer Simulation↗