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Biomedical subjects

X X Gao

Publications and source records attributed to X X Gao.

11 recordsLinked to original sources
PubMed1997

Regional differences of dura osteoinduction: squamous dura induces osteogenesis, sutural dura induces chondrogenesis and osteogenesis.

Dura plays an important role in calvarial morphogenesis. However, precisely what that role is remains unclear. We present here in vivo evidence that dura without other central nervous system components induces both chondrogenesis and osteogenesis. The mechanism is, at least in part, by proximate tissue interaction. The objectives of this experiment were to answer the following: (1) Can dura actually induce osteogenesis without the influence of the underlying brain? (2) What are the requirements of this dura-induced heterotopic osteogenesis? (3) What are the differences between dura underlying sutures and dura underlying the squamous portions of the cranial bones? Dura underlying the metopic, sagittal, and lambdoidal sutures and dura underlying the flat portions of frontal and parietal bones were obtained from neonatal Lewis rats and transplanted into the posterior thoraces of adult Lewis recipients. In group I, dura underlying the metopic, sagittal, and lambdoidal sutures (n = 20) and dura underlying the flat portions of frontal and parietal bones (n = 20) were transplanted individually into separate epitheliomesenchymal pockets. Group II animals had dura underlying the metopic, sagittal, and lambdoidal sutures (n = 10) and dura underlying the flat portions of frontal and parietal bones (n = 10) transplanted individually into surgically created mesenchymal pockets by placing the dura grafts between panniculus carnosus and latissimus dorsi muscles. The animals were sacrificed at 2-week intervals. Light microscopy, special histochemical analysis, immunohistochemistry, and electron microscopy were performed. Bone formation was seen in 15 of the 18 animals (83 percent) in group I. No bone or cartilage formation was seen in group II. Chondrogenesis was seen in 4 animals receiving dura underlying the metopic, sagittal, and lambdoidal sutures in group I. Cellular hyperproliferation was seen at 2 weeks when dura was transplanted close to the hair follicles. These cells had a high nucleus-to-cytoplasm ratio and were positive for transforming growth factor beta. This hyperproliferation was followed by production and accumulation of Alcian blue-positive extracellular matrix that resisted digestion by hyaluronidase. Cellularly active cartilage was seen at 6 weeks. There was no chondrogenesis in animals receiving dura underlying the flat portions of frontal and parietal bones in group I. Electron microscopy demonstrated the presence of proteoglycan-like ground substance and type II collagen in the inner layer of sutural dura and the predominance of dense type I collagen in the squamous dura and the external layer of the sutural dura. The important findings of this experiment are that (1) heterotopically transplanted neonatal dura can induce osteogenesis, (2) this heterotopic osteoinduction by dura requires epitheliomesenchymal interaction, and (3) separating dura into sutural dura and squamous dura, chondrogenesis occasionally occurred in addition to osteogenesis with the former, while only membranous ossification occurred with the latter, indicating intrinsic differences within the dura mater. This dural heterogeneity is supported by direct ultrastructural data.

Animals↗
PubMed1996

Daily spinal cord stimulation suppresses autotomy behavior in rats following peripheral deafferentation.

Autotomy in experimental animals following peripheral nerve section has been interpreted as a sign of pain corresponding to the chronic pain observed in patients with extensive nerve lesions. Such pain may be alleviated by spinal cord stimulation. In the present study, the effect of such stimulation, via chronically implanted electrodes, on autotomy behavior following sciatic nerve section was assessed in the rat. The stimulation was applied for 30 min daily during a 10-day period. There were four groups of animals, 16 in each, half of them females. Stimulating electrodes were implanted in all and one group served as control, receiving sham stimulation. In one group, the stimulation was started when autotomy was observed, one received stimulation from the day of nerve section, and in one it was begun three days before section. The onset of autotomy was significantly delayed in the latter two groups. When stimulation was applied as "treatment", autotomy ceased but reappeared after the 10-day stimulation period. The incidence and severity of autotomy was markedly delayed and reduced when the stimulation had been applied just after the nerve section or before. In the latter groups, the diminished degree of autotomy persisted for the entire observation period, lasting 60 days after the stimulation was stopped. It seems that spinal cord stimulation, albeit applied only once daily and during a limited time period, can protect the spinal cord from developing the state of hyperexcitability believed to be the major cause of autotomy behavior. Peripheral mechanisms may also play a role by the antidromic activity evoked by the stimulation in the sectioned peripheral nerve. This study shows that spinal cord stimulation, which is a commonly employed method for treating chronic neurogenic pain, may have long-lasting effects on plasticity changes in the spinal cord following peripheral nerve injury, even when the stimulation is applied for short periods of time.

Animals↗
PubMed1996

The effects of octreotide on healing of small bowel anastomosis.

Octreotide (OCT) is a somatostatin analog used for its inhibitory action on multiple GI functions. Although octreotide has numerous clinical benefits, it has also been shown to inhibit postresectional hyperplasia of small bowel and hepatic regeneration. Because octreotide inhibits both trophic and anabolic hormones, we hypothesize that the use of octreotide may be detrimental in patients with a recent bowel anastomosis. To test this hypothesis, 60 male rats were randomized to four equal groups following small bowel anastomosis. Group I = control; Group II = 10 mg/day of hydrocortisone succinate; Group III = 2.5 micrograms/kg/day octreotide (equivalent of a clinical dose); Group IV = 25 micrograms/kg/day octreotide. Hydrocortisone was used as a negative control because it is known to have inhibitory effects on small bowel anastomotic healing. On postoperative Day 7, bursting pressures were measured. Serum T-kininogen levels, as a marker for systemic inflammation, and hydroxyproline content from the anastomotic segments were obtained. These results indicate that in the rat small bowel model, octreotide did not have any deleterious effect on anastomotic strength, systemic inflammation, and collagen content, even at high doses. Hydrocortisone, as expected, showed significant detrimental effects on bursting strength, as well as decreasing systemic inflammation. These findings have significant clinical implications, as octreotide could be used without jeopardizing the intestinal anastomosis.

Anastomosis, Surgical↗
PubMed1992

T-kininogen, processing and functions.

Studies are presented which indicate that T-kininogen, the acute phase kininogen of the rat, could be a healing protein because of its properties as a cysteine protease inhibitor. Evidence is also presented that mRNA of T-kininogen synthesis may be a function of interleukin 6 production. A regulatory mechanism is postulated by which SH cofactors could determine if T-kinin is released or whether the T-kininogen molecule would remain intact. Evidence is also presented that T-kinin acts through kinin B2 receptors. No specific binding of bradykinin or T-kinin could be detected in rat heart preparations.

Acute-Phase Proteins↗
PubMed1991

[Relation between the clinical manifestations and electromyographic findings in motor neurone disease].

343 cases of motor neurone disease (MND) were examined with electromyography. The result showed EMG examination was of much vale in helping to ascertain an accurate diagnosis which clinically could be made in only about 1/4 of the series of cases. The ages of onset ranged from 4 months to 10 years with an average of 36.8 years. 56.8% under 40 years. There was a higher male preponderance, the male/female ratio being 3.2:1. It was 1.6:1 in a report from a western country. 123 cases showed only one limb involvement clinically while the EMG findings were also abnormal in the other three limbs. Fibrillation potentials were found to be at more than two sites in one muscle in 84.5% in this series, where as they occurred in 95-100% of the infantile and juvenile cases. Abundant fibrillation potentials were found in 37.1% of the cases within 3 years after the onset and in 13.6% in those with a longer duration. The increment of the mean duration of motor unit potential was 94.5% and that of the mean amplitude 91%. It seemed not necessary to emphasize giant potentials. The motor nerve conduction velocities (NCV) were normal in 95% while the sensory NCV were almost always normal (98%). All of the 3 cases tested with single fiber EMG showed an increment of jitter of 95-100% and a muscle fiber density of 2.95-3.65.

Amyotrophic Lateral Sclerosis↗
PubMed1991

[Amyotrophic lateral sclerosis: an analysis of 167 cases].

167 cases of amyotrophic lateral sclerosis treated in Peking Union Medical College Hospital were analyzed. There was a significant difference between some of the clinical features of amyotrophic lateral sclerosis in China and western countries. The age of onset in China was 10 to 20 years earlier than and the male to female ratio (4.6:1) was 2 times higher than those in the west. Average age of death was 47 years, being earlier than that in the west. Some specific clinical features for early clinical diagnosis were also discussed.

Adolescent↗
PubMed1987

Isolation of a thiol-activated T-kininogenase from the rat submandibular gland.

T-kininogenase (T-kgnase) activity has been investigated in tissues of the rat and submandibular glands of the rat, mouse and guinea pig. Both rat and mouse submandibular homogenates showed high T-kgnase activity. The enzyme has been purified 360-fold from rat submandibular gland homogenate supernatant fluid. The enzyme has an apparent molecular mass of 28 kDa and a pH optimum of 8.0 toward T-kininogen. It cleaved T-kininogen in catalytic quantities to release T-kinin (Ile-Ser-bradykinin) and small quantities of bradykinin and an unknown kinin. The activity of the enzyme was increased 10-fold in the presence of thiol groups (dithiothreitol) and inhibited by leupeptin (90%) and to a lesser extent by aprotinin (49%), TLCK (46%) and soybean trypsin inhibitor (27%). Pepstatin and PMSF did not inhibit the enzyme. Studies on substrate specificity, pH optimum and agents which inhibit T-kgnase activity demonstrate that this enzyme is different from plasma and tissue kallikreins, cathepsin D, esterase A and esterase B (other known kininogenases). It is the first thiol-activated kininogenase to be reported.

Animals↗