Immature Rabbits Research Articles

Effects of Cocarboxylase in Amikacin-Induced Ototoxicity in Immature Animals.

Possible otoprotective properties of cocarboxylase were studied on the model of amikacin-induced ototoxicity in immature rabbits. Auditory function was evaluated by the short-latency auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) tests. Administration of cocarboxylase after modeling of amikacin-induced ototoxicity resulted in a decrease in the ABR peak I threshold and prevented damage to the outer hair cells.

Effect of neurocentral cartilage destruction on spinal growth in immature rabbits.

ObjectiveThis study was performed to observe the effect of neurocentral cartilage (NCC) destruction on spinal growth in immature rabbits.MethodsThe NCC of the lumbar vertebrae of 24 4-week-old female rabbits was destroyed through posterolateral and anterior approaches, and three-dimensional computed tomography examinations were performed 3 months after the procedure.ResultsScoliosis was successfully induced in all rabbits of both the anterior and posterolateral approach groups. The scoliosis exceeded 10 degrees in three rabbits, which exhibited coronal scoliosis of the spine, unequal length and thickness of the bilateral pedicles, and rotation of the vertebrae. Scoliosis was not observed in the control group.ConclusionsDestruction of the unilateral NCC in immature rabbits can induce structural scoliosis, similar to the pathological features of human scoliosis. The Cobb angles are similar after NCC destruction by a posterolateral approach and under direct vision via the anterior approach.

Hormone-like activities of Kuntai capsule in the uteri of ovariectomized rats and immature rabbits

OBJECTIVETo investigate the hormone-like activities of Kuntai capsule (KTC) in the uteri of ovariectomized rats and immature rabbits. METHODSFollowing bilateral ovariectomy, rats were randomly divided into six groups including sham group, control group, estradiol valerate group, KTC 0.24, 0.6, and 1.5 g/kg groups. The rats were treated with 0.5% CMC-Na, estradiol valerate and KTC (0.24, 0.6, and 1.5 g/kg), respectively for 28 consecutive days. Then the estrous cycle, uterine changes and pathological changes were examined. Serum levels of estradiol (E2), and progesterone (P4) were measured by enzyme-linked immunosorbent assay (ELISA). Protein levels of estradiol receptor (ER), progesterone receptor (PR), vascular endothelial growth factor (VEGF), proliferating cell nuclear antigen (PCNA) and nuclear-associated antigen-67 (Ki-67) in uterine tissues were detected by western blot. Immature rabbits were estrogen-primed prior to intragastric administration with KTC for 6 d consecutively. Then, the uteri underwent hematoxylin-eosin staining to observe endometrial transformation. RESULTSCompared with the control group, 0.6 and 1.5 g/kg KTC markedly decreased the uterine organ coefficient and endometrial thickness (P < 0.05). The serum level of P4 was increased in the KTC 0.6 g/kg group (P < 0.05). There were no significant variations in the serum level of E2 in the KTC groups compared with the control group. ERβ, but not ERα, was markedly upregulated after KTC administration (P < 0.05). Furthermore, 1.5 g/kg KTC significantly decreased the protein level of PRA (P < 0.05) and 0.6 g/kg KTC increased the protein level of PRB in the uteri (P < 0.05). VEGF was highly expressed after treatment with 0.24 and 0.6 g/kg KTC, and Ki-67 was markedly reduced in ovariectomized rats treated with 1.5 g/kg KTC. No difference was found in the expression of PCNA. KTC 0.24 and 0.6 g/kg promoted endometrial transformation in immature rabbit uteri. CONCLUSIONKTC does not demonstrate obvious estrogen-like effect on uteri after ovariectomy, but it does exhibit weak progestogen-like effect, by which mechanism of action is yet to be further investigated.

Periosteum and Bone Marrow Effects on Bone Regeneration: Histomorphometric Evaluation of a Lengthening Model in Rabbit

Bone function requires a good repair system. The quantitative role of each healing component, mainly periosteum and bone marrow/endosteum and of their interactions is not clearly known. To evaluate more precisely the role of periosseous tissues in bone formation, we chose a bone lengthening model in rabbits. Nineteen purebred immature male New Zealand white rabbits were fitted with a femoral lateral external fixator and randomly assigned to 4 intervention groups: 1) Periosteum (PS) and bone marrow (BM) preservation; 2) PS preservation and BM destruction; 3) PS destruction and BM preservation; 4) PS and BM destruction. Animals were killed on day 30 and histology showed different bone regeneration modes. The most frequent ossification in the centre of the distraction gap was enchondral ossification. For bone formed between cortices only group 1 showed a difference (p=0.034). Density of the formed bone at the periosteal site showed a positive effect only with PS preservation, with an interaction of BM and PS. Density of group 4 was different from groups 1 (p=0.028), and 2 (p=0.001). No difference was present between groups at the endosteal sites. PS had a positive effect on the thickness of the formed bone at the periosteal site, with an interaction between PS and BM, but not at the endosteal site. A difference in thickness was noted between group 2 and 4 (p=0.018). Periosteum forms more bone and more likely to spread than bone marrow, but for restoration of the cortical wall, preservation of both shows optimal density results. Bone does not seem to form from surrounding tissues when both periosteum and bone marrow are destroyed.

Effects of Simvastatin on myocardial apoptosis and oxidative stress mechanism in immature rabbits with chronic heart failure

Objective To observe the effects of Simvastatin on myocardial apoptosis and oxidative stress mechanism in immature rabbits with chronic heart failure. Methods Thirty-six male New Zealand big-eared immature rabbits were randomly divided into 3 groups: Adriamycin(ADR)+ Simvastatin group(ADR-s group, n=12), in which ADR(1.5 mg/kg) received injection via the auricular vein of rabbits weekly, and the rabbits received oral Sim-vastatin [1.5 mg/(kg·d)] simultaneously for 12 weeks; ADR group(n=12), in which the rabbits received ADR like ADR-S group, and 9 g/L saline instead of Simvastatin; control group (CON group, n=12), which received the same amount of 9 g/L saline.Echocardiography examination was performed in 13th week.Myocardial fibrosis degree was detected by using MASSON staining, and the myocardial apoptosis was detected by using terminal deoxynucleotidyl transferase dUTP nick end labeling.Colorimetric method was used to detect the myocardial concentration superoxide dismutase (SOD) and malondialdehyde (MDA). Enzyme-linked immunosorbent assay was used to detect serum B-type brain natriuretic peptide (BNP) level. Results (1) In CON group, the immature rabbits were all alive.Four rabbits died in ADR group, and the survival rate was 66.7%, while 2 rabbits died in ADR-s group, and the survival rate was 83.3%.(2)Compared with CON group, the left ventricular end diastolic diameter (LVEDd) and left ventricular end systolic diameter (LVESd) in ADR-s group and ADR group increased [(11.90±1.09) mm, (11.34±0.92) mm vs.(10.73±0.48) mm; (9.80±0.88) mm, (8.47±1.23) mm vs.(7.31±0.36) mm]; left ventricular fractional shortening(LVFS) and left ventricular ejection fraction(LVEF) decreased [(17.65±1.70)%, (22.58±2.19)% vs.(31.79±2.58)%; (41.35±3.19)%, (49.17±3.53)% vs.(64.34±3.97)%], and all the differences were significant(all P<0.05); LVEDd and LVESd in ADR-s group were lower than those of ADR group, while LVEF and LVFS in ADR-s group were higher than those of ADR group, and the differences were significant(all P<0.05). (3) MASSON staining: compared with ADR group, there was less myocardial cell hyperplasia of fibrous tissue in ADR-s group.(4)Compared with CON group, the apoptosis index was higher in ADR and ADR-s group[(34.25±11.13)%, (24.00±6.85)% vs.(16.58±5.34)%], but ADR-s group had less than ADR group, and the diffe-rences were significant (all P<0.05). (5) Compared with ADR group, SOD activity of ADR-s group was higher[(13.40±2.68) kU/L vs.(10.66±2.99) kU/L], but MDA content was lower[(5.67±1.36) μmol/mg vs.(7.08±0.98) μmol/mg], and the differences were significant (all P<0.05). (6) Serum BNP level in ADR group and ADR-s group was higher than that of the CON group[(33.28±9.58) μg/L, (26.71±6.72) μg/L vs.(13.56±2.82) μg/L], while was higher in ADR group than that of ADR-s group, and the differences were significant (all P<0.05). Conclusions Simvastatin can protect cardiac function of immature rabbits with chronic heart failure.The possible mechanism may be the up-regulation of myocardial SOD activity, reduction of cell lipid peroxidation and inhibition of myocardial apoptosis. Key words: Simvastatin; Adriamycin; Chronic heart failure; Myocardial apoptosis; Oxidative stress

Effect of Successive Administration of Vancomycin and Amikacin on Auditory Function of Immature Animals.

Effect of successive administration vancomycin and amikacin in therapeutic doses on immature auditory organ was compared to single administration of the same drugs in chronic experiments on immature rabbits by recording of short-latency auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE). Drug administration always increased significantly the ABR peak I threshold. Ototoxic antibiotics did not change DPOAE, but selectively affected activity of outer hair cells. No enhancement of the ototoxic effects was observed after successive administration of the two antibiotics.

Repetitive Stresses Generate Osteochondral Lesions in Skeletally Immature Rabbits

Background: The origin of juvenile osteochondritis dissecans (OCD) is unknown. Existing experimental animal models of OCD most frequently involve surgically created lesions but do not examine repetitive stress as a possible cause of OCD. Hypothesis: Repetitive stresses can cause OCD-like lesions in immature animals. Study Design: Controlled laboratory study. Methods: Six juvenile rabbits were subjected to repetitive loading forces of approximately 160% body weight to the right hindlimb during five 45-minute sessions per week for 5 weeks. The contralateral limb was the unloaded control. After 5 weeks, rabbits were euthanized and examined with radiographs, micro–computed tomography, and gross and histopathologic analysis. Results: All 6 rabbits developed osteochondral lesions in loaded limbs on the medial and lateral femoral condyles, while contralateral unloaded limbs did not demonstrate lesions. Loaded limbs developed relative osteopenia in the femoral epiphysis and tibial metaphysis with associated decreased trabecular density. Loaded limbs also demonstrated increased femoral subchondral bone thickness near the lesions. Lesions did not have grossly apparent extensive articular cartilage damage; however, cartilage thickness increased on histology with reduced ossification. Loaded knees demonstrated abundant chondrocyte cloning, limited cartilage fissuring, and a focal loss of cellularity at the articular surface. Conclusion: Low-grade lesions in human OCD have little gross articular cartilage involvement despite substantial changes to the subchondral bone as shown on magnetic resonance imaging and radiographs. Histopathology findings in this study included cartilage thickening and chondrocyte cloning resembling those of recently published human OCD biopsy studies. Our animal model supports the hypothesis that repetitive stress to immature knees may contribute to the development of human OCD. This model may be useful in understanding the pathophysiology and healing of human OCD. Clinical Relevance: Repetitive physiologic stress generated changes to the subchondral bone in immature animals without causing extensive articular damage. The similarities of these lesions in gross and histologic appearance with human OCD support repetitive stress as the likely the cause for human OCD.

Role of endothelial permeability hotspots and endothelial mitosis in determining age-related patterns of macromolecule uptake by the rabbit aortic wall near branch points

Background and aimsTransport of macromolecules between plasma and the arterial wall plays a key role in atherogenesis. Scattered hotspots of elevated endothelial permeability to macromolecules occur in the aorta; a fraction of them are associated with dividing cells. Hotspots occur particularly frequently downstream of branch points, where lesions develop in young rabbits and children. However, the pattern of lesions varies with age, and can be explained by similar variation in the pattern of macromolecule uptake. We investigated whether patterns of hotspots and mitosis also change with age. MethodsEvans’ Blue dye-labeled albumin was injected intravenously into immature or mature rabbits and its subsequent distribution in the aortic wall around intercostal branch ostia examined by confocal microscopy and automated image analysis. Mitosis was detected by immunofluorescence after adding 5-bromo-2-deoxiuridine to drinking water. ResultsHotspots were most frequent downstream of branches in immature rabbits, but a novel distribution was observed in mature rabbits. Neither pattern was explained by mitosis. Hotspot uptake correlated spatially with the much greater non-hotspot uptake (p < 0.05), and the same pattern was seen when only the largest hotspots were considered. ConclusionsThe pattern of hotspots changes with age. The data are consistent with there being a continuum of local permeabilities rather than two distinct mechanisms. The distribution of the dye, which binds to elastin and collagen, was similar to that of non-binding tracers and to lesions apart from a paucity at the lateral margins of branches that can be explained by lower levels of fibrous proteins in those regions.

CORR Insights®: Periosteal Fiber Transection During Periosteal Procedures Is Crucial to Accelerate Growth in the Rabbit Model.

W e know that excessive compressive forces across a physis can inhibit growth [1, 5], while tensile forces may cause growth stimulation. The role of the periosteum as a potential ‘‘tether’’ to the adjacent growth plate has been speculated in previous studies [8, 11]. Furthermore, clinical investigators have implicated the torn (‘‘untethered’’) periosteum as a contributor to limb overgrowth following a pediatric femoral shaft fracture and asymmetric medial physeal growth leading to genu valgum after certain proximal tibial fractures in young children [2, 3, 9]. Although studies have shown that leglength discrepancy can be addressed by transecting or stripping the periosteum of the shorter limb in young patients [4, 6, 8, 10], I believe that few surgeons currently apply these principles in clinical practice. Perhaps due to the reported unpredictability [10] and the lack of robust basic-science support, this seemingly straightforward method of growth stimulation of the short leg has not gained the popularity enjoyed by surgical alternatives, such as gradual lengthening or a contralateral epiphysiodesis. Additionally, it is currently unknown whether the various purported methods of untethering the periosteum are equally effective in inducing and sustaining growth stimulation of the affected extremity. In this well-designed animal study, Halanski and colleagues have dug deeper and studied the effects of four distinct methods of periosteal release on the growth rates and lengths of tibiae in skeletally immature rabbits. They found that simply stripping the periosteum around the proximal tibial metaphysis without transection of the longitudinal fibers did not enhance growth, while circumferentially transecting the periosteum, (with or without its removal) does stimulate growth at the proximal and distal tibial physes, as noted 2 weeks posto peratively. Although this growth stimulation was not sustained 8 weeks after surgery at the proximal tibial physis in the animals undergoing a one-time release, repeat transection at 4 weeks postoperatively seemed to reignite the physis. This latter group of This CORR Insights is a commentary on the article ‘‘Periosteal Fiber Transection During Periosteal Procedures Is Crucial to Accelerate Growth in the Rabbit Model’’ by Halanski and colleagues available at: DOI: 10.1007/ s11999-015-4646-6. The author certifies that he, or any member of his immediate family, has no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/ licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. The opinions expressed are those of the writers, and do not reflect the opinion or policy of CORR or The Association of Bone and Joint Surgeons. This CORR Insights comment refers to the article available at DOI: 10.1007/s11999015-4646-6. S. Sabharwal MD, MPH (&) Department of Orthopedics, Rutgers New Jersey Medical School, 90 Bergen Street, Suite 7300, Newark, NJ 07103-2499, USA e-mail: sabharsa@njms.rutgers.edu CORR Insights Published online: 4 January 2016 The Association of Bone and Joint Surgeons1 2015

Auditory Function in Immature Animals after Two Consecutive Courses of Ototoxic Antibiotics.

In chronic experiments on immature rabbits receiving therapeutic courses of vancomycin, gentamicin, and consecutive administration of vancomicin and gentamicin by the scheme used in neonatology, hearing function was evaluated by the methods of auditory evoked potentials (auditory brainstem response, ABR) and distortion product otoacoustic emission (DPOAE). Comparison with the control group revealed ototoxic effects of all studied antibiotics that manifested in increased sound tolerance and more rapid shortening of latencies in 30-100 dB range. Higher thresholds were found only after gentamicin administration. Vancomycin administration significantly reduced the responses at 4 kHz. Subsequent gentamicin course did not potentiate this effect.

Mass transport properties of the rabbit aortic wall.

Uptake of circulating macromolecules by the arterial wall may be a critical step in atherogenesis. Here we investigate the age-related changes in patterns of uptake that occur in the rabbit. In immature aortas, uptake was elevated in a triangle downstream of branch ostia, a region prone to disease in immature rabbits and children. By 16-22 months, uptake was high lateral to ostia, as is lesion prevalence in mature rabbits and young adults. In older rabbits there was a more upstream pattern, similar to the disease distribution in older people. These variations were predominantly caused by the branches themselves, rather than reflecting larger patterns within which the branches happened to be situated (as may occur with patterns of haemodynamic wall shear stress). The narrow streaks of high uptake reported in some previous studies were shown to be post mortem artefacts. Finally, heparin (which interferes with the NO pathway) had no effect on the difference in uptake between regions upstream and downstream of branches in immature rabbits but reversed the difference in older rabbits, as does inhibiting NO synthesis directly. Nevertheless, examination of uptake all around the branch showed that changes occurred at both ages and that they were quite subtle, potentially explaining why inhibiting NO has only minor effects on lesion patterns in mature rabbits and contradicting the earlier conclusion that mechanotransduction pathways change with age. We suggest that recently-established changes in the patterns of haemodynamic forces themselves are more likely to account for the age-dependence of uptake patterns.

Further Studies on Glucophylline

Abstract Laboratory studies on dogs and rabbits treated with methylglucamine and glucophylline revealed: 1.1. Growth of immature rabbits is not disturbed. These animals made increases in size and weight commensurate with normal controls. 2.2. The dogs, treated and controls, all lost weight—a condition due probably to food and housing restraint. 3.3. Histologic study of brain, heart, lung, spleen, kidney, and liver of both dogs and rabbits showed no harmful effects that might be attributed to the drug. 4.4. Significant figures setting forth results are appropriately tabulated.

Demineralized Bone Matrix Injection in Consolidation Phase Enhances Bone Regeneration in Distraction Osteogenesis via Endochondral Bone Formation.

BackgroundDistraction osteogenesis (DO) is a promising tool for bone and tissue regeneration. However, prolonged healing time remains a major problem. Various materials including cells, cytokines, and growth factors have been used in an attempt to enhance bone formation. We examined the effect of percutaneous injection of demineralized bone matrix (DBM) during the consolidation phase on bone regeneration after distraction.MethodsThe immature rabbit tibial DO model (20 mm length-gain) was used. Twenty-eight animals received DBM 100 mg percutaneously at the end of distraction. Another 22 animals were left without further procedure (control). Plain radiographs were taken every week. Postmortem bone dual-energy X-ray absorptiometry and micro-computed tomography (micro-CT) studies were performed at the third and sixth weeks of the consolidation period and histological analysis was performed.ResultsThe regenerate bone mineral density was higher in the DBM group when compared with that in the saline injection control group at the third week postdistraction. Quantitative analysis using micro-CT revealed larger trabecular bone volume, higher trabecular number, and less trabecular separation in the DBM group than in the saline injection control group. Cross-sectional area and cortical thickness at the sixth week postdistraction, assessed using micro-CT, were greater in the regenerates of the DBM group compared with the control group. Histological evaluation revealed higher trabecular bone volume and trabecular number in the regenerate of the DBM group. New bone formation was apparently enhanced, via endochondral ossification, at the site and in the vicinity of the injected DBM. DBM was absorbed slowly, but it remained until the sixth postoperative week after injection.ConclusionsDBM administration into the distraction gap at the end of the distraction period resulted in a significantly greater regenerate bone area, trabecular number, and cortical thickness in the rabbit tibial DO model. These data suggest that percutaneous DBM administration at the end of the distraction period or in the early consolidation period may stimulate regenerate bone formation and consolidation in a clinical situation with delayed bone healing during DO.

Effect of gentamicin on the auditory analyzer in sexually immature animals.

Auditory function of immature rabbits was evaluated using two electrophysiological methods, brainstem auditory evoked response (BAER) and distortion product otoacoustic emission (DPOAE), in chronic experiments following administration of therapeutic doses of gentamicin. Impairment of auditory function manifested in increased thresholds and decreased amplitude of the 1st BAER peak was established. DPOAE parameters were not significantly changed. It was suggested that gentamicin decreased activity of spiral ganglion neurocytes in animals with immature auditory analyzer.

Effects of varying doses of simvastatin on protein kinase A in immature rabbits with chronic heart failure

Objective To investigate the effects of varying doses of simvastatin (SIM) on protein kinase A(PKA), ventricular remodeling and heart function in immature rabbits with chronic heart failure (CHF), to explore the possible mechanisms for simvastatin on CHF. Methods Sixty male immature rabbits were randomly divided into 5 groups: control (CON) group, CHF model group, small-dose simvastatin (SD-SIM) group[SIM concentration was 0.3 mg/(kg·d)], medium-dose simvastatin (MD-SIM)group[SIM concentration was 1.5 mg/(kg·d)], and the high-dose simvastatin (HD-SIM)group[SIM concentration was 3.0 mg/(kg·d)]. The general condition of immature rabbits in the experiment group was evaluated.Color doppler ultrasonography was used to detect the left ventricular structure and the function.The left ventricular myocardium was taken and fixed in paraformaldehyde (40 g/L). The expression of PKA was evaluated by immunohistochemical assay. Results In CON group, the rabbits were all alive; in the other groups, most immature rabbits were unhairing, with diet reduction, weight lose and sluggish with hyperkeratosis.Overall survival rate was 82%(49/60 cases). The mortality rate in CHF model group was significantly higher than that in the MD-SIM group(41.7% vs 8.3%, P<0.05). Compared with the CON group, left ventricular ejection fraction(LVEF) in the SD-SIM group, HD-SIM group and CHF model group all dropped sharply (all P<0.01), while the left ventricular end diastolic diameter (LVEDd) and left ventricular end systolic diameter (LVESd) increased markedly (all P<0.01). Compared with CHF model group, LVEDd and LVESd decreased and LVEF increased significantly in SD-SIM group, HD-SIM group and MD-SIM group(all P<0.05), the effects of MD-SIM group was the best(P<0.05). LVEF in MD-SIM group increased significantly compared with SD-SIM group, HD-SIM group and CHF model group (all P<0.05). PKA expression in SD-SIM group, MD-SIM group and HD-SIM group increased significantly compared to the CHF model group and CON group (all P<0.01). Compared with the SD-SIM group and HD-SIM group, the expression of MD-SIM group significantly increased (P<0.05). Conclusions Simvastatin can reverse the left ventricular remodeling and improve the heart function of immature rabbits with CHF.The effect of MD-SIM was the best.The mechanism of simvastatin may be correlated to up-regulating the expression of PKA. Key words: Simvastatin; Adriamycin; Chronic heart failure; Protein kinase A

Effects of different doses of simvastatin on connective tissue growth factor and osteoprotegerin of immature rabbits with chronic heart failure

Objective To observe the effects of different doses of simvastatin on immature rabbit models of chronic heart failure(CHF) and to explore the mechanism of simvastatin in the rabbits with CHF. Methods Sixty male immature rabbits were randomly divided into 5 groups: control(CON) group, CHF group, small-dose simvastatin(SD-SIM) group, medium-dose simvastatin(MD-SIM) group, and the high-dose simvastatin(HD-SIM) group, 12 cases in each group.The models of CHF were established by injecting adriamycin(ADR) via the auricular vein of rabbits.In the first injection of ADR, simvastatin tablets [concentration of 0.3, 1.5, 3.0 mg/(kg·d), respectively] were given to the rabbits by intragastric administration for SD-SIM, MD-SIM, and HD-SIM models.The general conditions of immature rabbits in experiment group were evaluated.Hemodynamic data were detected.HE staining was used to observe structure of myocardial cells.The plasma level of osteoprotegerin(OPG) was measured by enzyme-linked immunosorbent assay (ELISA). The expression of connective tissue growth factor(CTGF) was evaluated by immunohistochemical assay. Results 1.In CON group, the rabbits were all alive; in CHF, SD-SIM, MD-SIM and HD-SIM groups, most immature rabbits had skinchapped, unhaired and sluggish with hyperkeratosis, diet reduction, and losing weight.Overall survival rate was 76.7%.2.Hemodynamic data indicated that the + dp/dtmax, -dp/dtmax and the left ventricular systolic pressure (LVSP) in the SD-SIM, HD-SIM and CHF groups dropped significantly compared with the CON group (all P<0.05). There was a remarkable increase in the SD-SIM, HD-SIM and MD-SIM groups compared with CHF group (all P<0.01); and there was a remarkable drop in the cardiac function of the SD-SIM and HD-SIM groups compared with MD-SIM group (P<0.05).3.Compared with the CON group, CTGF and OPG expression in the SD-SIM, MD-SIM, HD-SIM and CHF groups increased significantly (P<0.01), while the expression in the SD-SIM, MD-SIM and HD-SIM groups decreased significantly compared with that of the CHF group (P< 0.05). Compared with the MD-SIM group, the expression of CTGF and OPG in the SD-SIM and HD-SIM groups increased significantly (P<0.05). Conclusions Simvastatin can improve cardiac function of rabbits with CHF significantly, and the effect on MD-SIM group is the best.The mechanism of simvastatin may depress the expressions of CTGF and OPG.CTGF and OPG can predict CHF. Key words: Simvastatin; Chronic heart failure; Connective tissue growth factor; Osteoprotegerin

GLYCOSAMINOGLYCAN CHANGES IN REGENERATIVE MENISCI OF THE IMMATURE RABBITS — HISTOLOGICAL AND SPECTROPHOTOMETRIC QUANTITATION

Purpose: This study was conducted primarily to compare the contents and distribution of Glycosaminoglycan (GAG) in the normal and regenerated menisci, and partly to elucidate the role of GAG in the meniscus to fulfill its function. Method: A total of 60 immature rabbits, weighing 300–400 gm and aged 4 weeks, were used for the study. Total medial meniscectomy in the right knee joint was performed in all rabbits. The medial menisci of the left knee joints were used as control. After 16, 20, 24 and 28 weeks postoperatively, the amount of GAG in normal and regenerated menisci were measured. For the measurement of quantity and distribution of GAG contents, photon absorptiometry and Safranin O staining method were used. Results: (1) In 48 of the 60 medial meniscectomized knees, menisci were regenerated in various sizes with degenerative changes of joints, especially on tibial side. (2) In normal menisci, GAG was distributed at inner and middle 1/3, while GAG in regenerated menisci was diffusely found in the entire width. (3) The concentration of GAG per 1 mg of regenerated menisci were 4.36 ± 1.68, 4.58 ± 1.14, 4.65 ± 2.21, 4.60 ± 2.06 μg in each 16, 20, 24, and 28 week groups, while those of normal menisci were 9.10 ± 2.09, 9.75 ± 3.97, 11.80 ± 8.44 and 14.51 ± 8.91 μg. (4) In normal menisci, the amount of GAG was gradually increased as rabbit got older. However, there was no statistical differences of quantitative amount of GAG of regenerated menisci among the 16, 20, 24, and 28 weeks groups during the observation periods (p &gt; 0.05). (5) There was a distinctive difference in Safranin O stainability by every 4 μg increase of GAG in both 1 mg of normal and regenerated menisci. Conclusion: This study showed the quantitative change of GAG between normal and regenerated menisci, and comparative analysis of GAG contents in the menisci by biochemical method and histological method were found to be useful tools.

Propofol protects the immature rabbit heart against ischemia and reperfusion injury: impact on functional recovery and histopathological changes.

The general anesthetic propofol protects the adult heart against ischemia and reperfusion injury; however, its efficacy has not been investigated in the immature heart. This work, for the first time, investigates the cardioprotective efficacy of propofol at clinically relevant concentrations in the immature heart. Langendorff perfused rabbit hearts (7–12 days old) were exposed to 30 minutes' global normothermic ischemia followed by 40 minutes' reperfusion. Left ventricular developed pressure (LVDP) and coronary flow were monitored throughout. Lactate release into coronary effluent was measured during reperfusion. Microscopic examinations of the myocardium were monitored at the end of reperfusion. Hearts were perfused with different propofol concentrations (1, 2, 4, and 10 μg/mL) or with cyclosporine A, prior to ischemic arrest and for 20 minutes during reperfusion. Propofol at 4 and 10 μg/mL caused a significant depression in LVDP prior to ischemia. Propofol at 2 μg/mL conferred significant and maximal protection with no protection at 10 μg/mL. This protection was associated with improved recovery in coronary flow, reduced lactate release, and preservation of cardiomyocyte ultrastructure. The efficacy of propofol at 2 μg/mL was similar to the effect of cyclosporine A. In conclusion, propofol at a clinically relevant concentration is cardioprotective in the immature heart.

Xanthine oxidase does not contribute to apoptosis after brain hypoxia-ischemia in immature rabbits.

Background. The mechanisms involving the initiation of apoptosis after brain hypoxia-ischemia through caspase activation are not fully defined. Oxygen free radicals may be an important mediator of caspase initiation with reactive oxygen species generated by xanthine oxidase (XO) being one potential source. The purpose of this study was to examine the role of XO in apoptosis after global cerebral injury. Methods. Immature rabbits were subjected to 8 minutes hypoxia and 8 minutes ischemia and then 4 hours of reperfusion. In one group (n = 5), the XO substrate xanthine was infused to generate more oxygen free radicals to promote apoptosis while in another (n = 5), the XO inhibitor allopurinol was given to reduce apoptosis by preventing free radical production (n = 5). Control animals (n = 4) received the vehicles. Caspase 3, 8, and 9 enzyme activities were measured in the cerebral cortex, hippocampus, cerebellum, thalamus, and caudate. Results. Administration of xanthine increased (P < 0.05) caspase 3 activity but only in the hippocampus, and pretreatment with allopurinol did not reduce it. No differences (P > 0.05) were found in any other region nor were there any changes in caspases 8 or 9 activities. Conclusion. We conclude that XO is not a major factor in inducing apoptosis after hypoxic-ischemic brain injury.

Modulation of C16:0‐ceramide in hypertrophied immature hearts by losartan

The angiotensin type 2 receptor plays a unique role in growth inhibition in adult myocardium via modulation of ceramide synthesis. Angiotensin type 1 (AT1 )-receptor blockade results in increased angiotensin type 2 receptor activation by angiotensin II, and AT1 -receptor blockers are sometimes prescribed to children for the treatment of cardiac hypertrophy or heart failure. We investigated the changes of ceramide lipid components in hypertrophied immature rabbit hearts after chronic administration of the AT1 -receptor blocker, losartan. One-week-old Japanese white rabbits were randomly divided into three groups: sham-operated control rabbits (Group S), rabbits given distilled water orally for 21 days after aortic constriction (Group H), and rabbits given losartan orally for 21 days after aortic constriction (Group H + L). Compared with Group S, the hypertrophy index and left ventricular posterior wall thickness were significantly increased in Group H, but were not different in Group H + L. Total myocardial ceramide levels in Group H and Group H + L were suppressed compared with Group S. The relative fatty acid components of myocardial ceramide in Group H were the same as those in Group S, but Group H + L showed a significant increase in the C16 :0 component. The total cardiac ceramide levels are depressed by pressure overload of immature rabbit hearts. Losartan reduced the hypertrophy with selective increase of the relative amount of C16:0 -ceramide.