[The protective effect of alpha-2 adrenergic agonist on cranial nerve in rats with brain injury].

OBJECTIVE: To investigate the neuroprotective effect of α2 adrenergic agonist, dexmedetomidine on tumor necrosis factor α (TNF-α), interleukin-6 (IL-6) in brain tissue and serum S-100ß protein level in traumatic brain injury rats. METHODS: Seventy-two male Sprague-Dawley rats were randomly divided into sham operation group (group S), traumatic brain injury group (group C), and dexmedetomidine group (group D), 24 rats in each group; each of which was divided into 6, 12, 24 and 48 hours subgroup, 6 rats in each subgroup. Parietal brain contusion was produced by reformed Feeney method. The group S underwent sham operation without blunt force stroke; group D underwent blunt force stroke, then received loading dose of dexmedetomidine, 3 µg/kg with common jugular vein injection and continued infusion with 3 µg·kg(-1)·h(-1) for 2 hours. The total dosage of dexmedetomidine was 9 µg/kg with a volume of 4 ml; group C underwent 0.9% NaCl, 4 ml injection at the same time point with the same method. The S-100 protein activity in arteria cruralis serum was detected at the each time point by ELISA and TNF-α, IL-6 in the brain tissue were detected by ELISA. RESULTS: There were no significant difference of TNF-α activity among time point of 6, 12, 24 and 48 h in group S ((2.07±0.06), (2.01±0.03), (2.11±0.05), and (2.08±0.04) pg/mg, F=1.147, P>0.05), no significant difference of IL-6 activity among the same time point ((4.03±0.06), (4.07±0.09), (4.06±0.04), and (4.55±0.09) pg/mg, F=1.176, P>0.05), and no significant difference of serum S-100ß activity among the same time too ((0.37±0.07), (0.36±0.02), (0.35±0.06), and (0.39±0.11) µg/L, F=1.045, P>0.05). The above indexes in group C were higher than those in group S, and the above indexes in group D were higher than those in group S and lower than those in group C (all P<0.05). CONCLUSION: Alpha-2 adrenergic agonist, dexmedetomidine could dramatically inhibit inflammatory reaction induced by traumatic brain injury in rats and protect brain tissue.

Carbon and nitrogen cycling in the Zhubi coral reef lagoon of the South China Sea as revealed by 210Po and 210Pb.

The radionuclides (210)Po and (210)Pb were examined to trace the cycling of particulate organic carbon (POC) and particulate organic nitrogen (PON) in the Zhubi coral reef lagoon. The net export flux of POC to the open sea is 14 mg Cm(-2) d(-1). However, the net exchange of PON has not yet been observed. On average, the vertical export fluxes in the lagoon of POC and PON, as derived from (210)Po/(210)Pb disequilibria, are 43 mg Cm(-2) d(-1) and 13.8 mg Nm(-2) d(-1), respectively. The deficit of (210)Po relative to (210)Pb in particulate matter provides evidence for the degradation of particulate organic matter. According to the mass balance budgets, 310 mg Cm(-2) d(-1) and 121 mg Nm(-2) d(-1) were recycled into dissolved fractions. Based on a first-order kinetics model, the degradation rate constants of POC and PON are 0.28 and 0.30 m(-1), respectively. Thus, (210)Po and (210)Pb can quantify the cycling of carbon and nitrogen in this coral lagoon.

A large excess of 210Po in the overlying water of the Zhubi Coral Reef flat, in the South China Sea.

The temporal variability of (210)Po and (210)Pb was examined in the overlying water of the Zhubi Coral Reef flat to detect nutrient-like behavior of (210)Po. Different mechanisms influencing their geochemical behaviors were observed. Excess (210)Po relative to (210)Pb revealed an additional input of (210)Po other than in situ production from (210)Pb. The (210)Po input comes from the reef flat sediment through diffusion. The diffusion contributes 62% of the total (210)Po. This diffusion of (210)Po directly highlights its nutrient-like behavior. No input, but the slight removal, of (210)Pb was observed. Fractionation factors indicate that particulate matter prefers to adsorb (210)Po rather than (210)Pb. In combination with particulate composition, (210)Po diffusion was closely related to organic matter. These results reveal that (210)Po might be a potential tracer for quantifying nutrient recycling in the Coral Reef system.

Observations of subchondral plate advancement during osteochondral repair: a histomorphometric and mechanical study in the rabbit femoral condyle.

OBJECTIVE: The subchondral plate and its reconstitution has been an under-researched aspect of articular cartilage repair. The extent to which the subchondral plate is restored by natural healing remains controversial. This study aimed to quantify advancement of subchondral bone during repair of an osteochondral defect, and to examine the effect of subchondral bone height on the quality of articular surface repair. DESIGN: Osteochondral defects, 3mm diameter by 3mm deep, were made by controlled drilling through the articular surface into the subchondral bone in femoral condyles of 33 rabbits. The repair response was examined at 8, 16 and 32 weeks (n=14, 12 and 7, respectively) post surgery. The specimens were subjected to mechanical testing, radiography, histology and histomorphometrology using an image analysis system. RESULTS: At 8 weeks, the level of reparative subchondral bone was 0.79+/-0.36 mm below the native tidemark. By 16 weeks, reformed subchondral plate was irregular, showing that 76.5% of the plate had extended beyond the native tidemark (0.13+/-0.05 mm) whilst 16.9% of the plate remained below (0.19+/-0.15 mm). The repaired surface non-osseous layer became thinner than the adjacent cartilage (0.23+/-0.08 vs 0.38+/-0.11 mm, P<0.05). This persisted up to 32 weeks. The repaired surface layers showed disappearance of safranin-O staining, increased separation splits at the boundary, and eventual degradation. General histological scores were similar across 8, 16 and 32 weeks although the scores of defect filling and restoration of osteochondral junction were decreased from 8 to 16 weeks. Mechanically, repaired defects had lower contact pressure and greater indentation than the normal controls at all time (P<0.05). Indentations of the cartilage adjacent to the defects were also greater than the normal at 8 and 32 weeks (P<0.05). CONCLUSION: The reparative subchondral bone advanced beyond the level of the native subchondral plate by 16 weeks in osteochondral defects of the rabbit femoral condyles. The presence of an advanced and irregular subchondral plate was associated with degradation of repaired articular surface. Abnormal subchondral plate is likely one of the major factors in influencing the long-term outcome of articular cartilage repair.

Evaluation of Gateshead carbon fibre rod as an implant material for repair of osteochondral defects: a morphological and mechanical study in the rabbit knee.

Use of the Gateshead carbon fibre rod system remains controversial. Although it has been shown to enhance the repair of lesions in load bearing areas of convex articular surfaces, there is a lack of evidence to support the claim that it provides an inert scaffold for ingrowth of organised fibrous tissue. and thereby increasing the rate and quality of articular surface regeneration. This study examined osteochondral repair following implantation of a Gateshead rod in the femoral condyles of 25 rabbits for up to 32 weeks. using radiology, histology, scanning electron microscopy and mechanical testing. The repaired fibrocartilaginous surface layer was found to be persistently softer than the normal control and some repaired surfaces were worn, exposing the rod at 32 weeks. Whilst fibrous tissue grew into the outer braided sheath of the rod, the core remained impervious. The rod appeared to act as a space occupier, initially providing better subsurface support than found in natural healing. In the long term, however, it prevented subchondral bone restoration and re-establishment of the normal osteochondral junction, resulting in a quality of repair which did not differ from that found in naturally healing defects.

Exacerbations of Bronchitis: bronchial eosinophilia and gene expression for interleukin-4, interleukin-5, and eosinophil chemoattractants.

Eosinophilia has been reported during exacerbations of bronchitis, but the mechanisms of tissue recruitment of eosinophils are unclear. We quantified eosinophils and the concurrent expression of cytokines and chemokines probably responsible for the tissue eosinophilia in bronchial biopsies obtained from three groups of nonatopic subjects: (1) healthy nonsmokers (n = 7; FEV1 % predicted = 108 +/- 4 [mean +/- SEM]); (2) nonasthmatic smokers with chronic bronchitis (CB) in a stable phase of their disease (n = 11; FEV1 % predicted: 75 +/- 5); and (3) nonasthmatic subjects with CB who sought medical advice for an exacerbation of their condition (n = 9; FEV(1) % predicted: 61 +/- 8). We applied anti-EG2 antibody and immunostaining to detect and count eosinophils. We performed in situ hybridization to visualize and enumerate cells expressing the genes for interleukin (IL)-4 and IL-5 and the eosinophil chemokines eotaxin, monocyte chemoattractant protein (MCP)-4, or regulated on activation, normal T-cell expressed and secreted (RANTES). We confirmed an increase in EG2-positive eosinophils in patients with CB in exacerbation. We found messenger RNA (mRNA) positivity for IL-4 and IL-5 in CB, but the between-group differences were not statistically significant. However, the numbers of lymphomononuclear cells expressing eotaxin mRNA were significantly greater in the smokers with CB than in the healthy nonsmokers without CB (p < 0.01). Following an exacerbation, RANTES expression was upregulated and this chemokine was strongly expressed in both the surface epithelium and in subepithelial lymphomononuclear cells: only RANTES showed a significant positive correlation with the increasing number of EG2-positive cells (r = 0.51; p < 0.03). In conclusion, an allergic profile of inflammation can also occur in CB: the marked upregulation of RANTES in the epithelium and subepithelium most likely accounts for the increased eosinophilia associated with an exacerbation of bronchitis.

Histopathologic changes in growth-plate cartilage following ischemic necrosis of the capital femoral epiphysis. An experimental investigation in immature pigs.

BACKGROUND: The developing capital femoral epiphysis consists of a secondary center of ossification surrounded by epiphyseal cartilage. Between the epiphyseal cartilage and the secondary center of ossification is a growth plate, which contributes to the circumferential increase in size of the secondary center of ossification during development. The main objective of this study was to describe the histopathologic changes that occur in the growth plate surrounding the secondary center of ossification during the early and reparative phases following the induction of ischemic necrosis of the capital femoral epiphysis in immature pigs. METHODS: Ischemic necrosis of the capital femoral epiphysis was induced in eighteen piglets by placing a nonabsorbable suture ligature around the femoral neck following a capsulotomy and transection of the ligamentum teres. The animals were killed three days to eight weeks following the induction of ischemia, and visual, radiographic, and histologic assessments were performed. RESULTS: Two to four weeks after the induction of ischemic necrosis, the growth plate surrounding the secondary center of ossification became necrotic. The observed histopathologic changes included chondrocyte death, loss of safranin-O staining of the matrix of the necrotic growth-plate cartilage, an absence of vascular invasion of terminal hypertrophic chondrocytes, and a decrease in the amount of primary spongiosa, indicating cessation of endochondral ossification. In the reparative phase, at four to eight weeks postoperatively, chondrocyte clusters and intense safranin-O staining were observed in the epiphyseal cartilage around the necrotic growth-plate cartilage. In the peripheral region of the femoral head, necrotic growth-plate cartilage surrounding the secondary center of ossification was resorbed by a fibrovascular tissue from the marrow space. By six weeks, new accessory centers of ossification with restored endochondral ossification were observed in the peripheral epiphyseal cartilage. New ossification centers contributed to the fragmented radiographic appearance of the secondary center of ossification. The physis appeared essentially normal in most animals, although five of the eighteen piglets showed mild or moderate histopathologic changes. CONCLUSIONS: In this model, ischemic necrosis of the capital femoral epiphysis resulted in necrosis of the growth plate surrounding the secondary center of ossification. Small new ectopic centers of ossification appeared in the epiphyseal cartilage, explaining in part the fragmented radiographic appearance of the secondary center of ossification.

Biocompatibility of NDGA-polymerized collagen fibers. II. Attachment, proliferation, and migration of tendon fibroblasts in vitro.

The material properties of collagen fibers polymerized with nordihydroguaiaretic acid (NDGA) are equivalent to native tendon, suggesting that NDGA crosslinking may provide a viable approach to stabilizing collagenous materials for use in repairing ruptured, lacerated, or surgically transected fibrous tissues, such as tendons and ligaments (Koob & Hernandez, Biomaterials, in press). The present study evaluated the biocompatibility of these fibers with cultured bovine tendon fibroblasts. Fibroblast attachment, migration, and proliferation on NDGA-crosslinked materials were compared to those on prepolymerized type I tendon collagen constructs as well as on tissue-culture-treated plastic. Fibroblast attachment on NDGA-crosslinked collagen fibrils was equivalent to attachment on plates coated with collagen alone. Over a period of 8 days in culture, attached fibroblasts proliferated on NDGA-crosslinked collagen at a rate identical to that of fibroblasts attached to native collagen. In order for the biomaterial effectively to bridge gaps in fibrous tissues, fibroblasts must be able to migrate and replicate on the bridging fiber. Control and crosslinked fibers were inserted in calf tendon explants, with a portion of the fiber extending out of the sectioned end of the tendon. Explants were cultured for 9 weeks, and the number of cells was measured at weekly intervals. Cells appeared on the fibers after 1 week of culture. By 2 weeks, cells had colonized the entire fiber. The number of cells continued to increase throughout the 9 weeks in culture, forming a layer several cells thick. Histologic analysis indicated that the fibroblasts populating the fibers appeared to originate in the epitenon. There was no difference in the rate of fibroblast migration and replication, nor in the ultimate number of colonizing cells, between control collagen fibers and NDGA-crosslinked fibers. NDGA-crosslinked fibers may provide a means of bridging gaps in ruptured, lacerated, or surgically transected tendons by providing a mechanically competent scaffold on which tendon fibroblasts can migrate, attach, and proliferate.

Comparative plasma and tissue pharmacokinetics and drug residue profiles of different chemotherapeutants in fowls and rabbits.

Blood and tissue pharmacokinetics and drug residue profiles of six chemotherapeutants were studied. Ceftriaxone (CEF), intravenously at 50 mg/kg, sulfamonomethoxine (SMM) and sulfaquinoxaline (SQ), orally at 200 mg/kg, and olaquindox (OLA), orally at 50 mg/kg, were administered to young broilers. Penicillin (PEN), intramuscularly at 200,000 U/kg, and albendazole (ALB), orally at 20 mg/kg, were given to rabbits. For each drug, 13-18 groups (n = 5-10 individuals/group) of the dosed animals were killed at different post-dosing times. Drug and/or metabolite concentrations in plasma, liver, kidney, heart, lung, and muscle tissues were analysed by HPLC procedures. Multi-exponential kinetic models were fitted to the observed tissue concentration-time data by applying a non-linear least-squares regression computer program. Tissue half-life, peak tissue concentration, and time of peak tissue concentration were determined. Half-life of CEF, SMM, SQ, OLA, PEN, ALB, and two metabolites of ALB (sulfoxide and sulfone) in various tissues ranged 0.6-1.4, 4.7-9.0, 4.5-18.9, 1.8-3.1, 0.9-3.0, 3.4-9.6, 5.0-16.1 and 7.4-12.2 h. The times required for CEF, SMM, SQ, OLA, PEN, and ALB residue concentrations to decline to 0.1 microgram/g in various tissues ranged from 5.0-11.6, 70.0-110.5, 114.0-179.8, 21.3-30.3, 4.1-24.8 and 47.8-84.4 h. Drug kinetic characteristics in tissues differed significantly from those in plasma, and also varied from tissue to tissue. It is necessary, therefore, to evaluate tissue kinetics when designing dosage regimens in tissue infection chemotherapy with these drugs. Knowledge of tissue kinetics is also important in predicting and controlling drug residues in edible tissues of food-producing animals.

Evidence for two distinct locomotory phenotypes of Treponema denticola ATCC 35405.

Using a two-layer system, a bottom layer containing treponema cells suspended in NOS (New Oral Spirochete)-Noble agar medium or NOS-Bacto agar medium and overlaid with cell-free NOS-agarose medium resulted in the spirochete cells migrating into the top layer. However, if the positions of the medium layers were reversed with the cells inoculated into the bottom layer containing NOS-agarose, there was no migration into the upper layer. This suggests migration of the spirochetes away from Bacto and Noble agars. Using a 3-layer system in which cells were inoculated into a middle layer consisting of NOS-agarose medium and sandwiched between cell-free NOS-agarose medium layers, cells remained within the middle layer. If the cells were inoculated into a middle layer consisting of NOS-Bacto agar medium while the upper and lower layers remained unchanged, cells migrated into both upper and lower layers. If cells that had migrated into the upper layer were transferred into a middle layer, they virtually all migrated into the upper layer repeatedly. Cells that had migrated into the lower layer and transferred to the middle layer migrated repeatedly into the lower layer. These results suggest the possible existence of two distinct locomotory phenotypes within this strain of treponeme.

Enumeration of viable oral spirochetes from periodontal pockets.

We recently developed a successful method for quantifying oral anaerobic spirochetes in pure culture by a viable count. New oral spirochete medium was used with low temperature-gelling agarose in polystyrene tissue-culture flasks. We have extended the use of this method to determine the viable count of spirochetes from periodontal pockets. Sixteen subgingival plaque samples were obtained by insertion of sterile paper points into deep periodontal pockets. The points were placed into reduced transport medium at chairside, vortexed in the microbiology laboratory and aliquots of the medium inoculated into molten new oral spirochete-agarose medium (37 degrees C) containing rifampin (20 micrograms/ml) in a flask. Subsequent dilutions were made from this initial flask to other flasks containing selective medium in sequence. All flasks were incubated anaerobically. Most other subgingival bacteria were selectively inhibited by rifampin. Spirochete colonies were typically spherical and were either dense or cottony. Their identities were checked by darkfield examination. Counts of colony-forming units of cultivable spirochetes ranged from 12.5% to 28.2% of the total cultivable anaerobic flora by the method described.

Self-pumped phase conjugation induced by an incoherent beam.

An incoherent beam was used to induce the self-pumped phase-conjugate output in a (BaSr) TiO(3) crystal. It was found that, in terms of the alteration of the signal-beam parameters, the induced self-pumped phase-conjugate output could be eliminated or maintained after the incoherent beam was removed. The observed effects were attributed to the local modification of the fanning geometry of the signal beam.