Mid-term function and remodeling potential of tissue engineered tricuspid valve: Histology and biomechanics

ObjectiveTricuspid valve reconstruction using a small intestinal submucosal porcine extracellular matrix (ECM) tube graft is hypothesized to be durable for six months and show signs of recellularization and growth potential. The purpose was to histologically and biomechanically test ECM valves before and after six months of implantation in pigs for comparison with native valves.MethodsTen 60 kg pigs were included, which survived tricuspid valve tube graft insertion. Anterior and septal tricuspid leaflets were explanted from all animals surviving more than one month and examined histologically (n = 9). Endothelialization, collagen content, mineralization, neovascularization, burst strength and tensile strength were determined for native valves (n = 5), ECM before implantation (n = 5), and ECM after six months (n = 5).ResultsCollagen density was significantly larger in ECM at implantation (baseline) compared to native leaflet tissue (0.3 ± 0.02 mg/mm³ vs. 0.1 ± 0.03 mg/mm³, p < .0001), but collagen density decreased and reached native leaflet collagen content, six months after ECM implantation (native vs. ECM valve at six months: 0.1 ± 0.03 mg/mm³ vs. 0.2 ± 0.05 mg/mm³, p = .8).Histologically, ECM valves showed endothelialization, host cell infiltration and structural collagen organization together with elastin generation after six months, indicating tissue remodeling and -engineering together with gradual development of a close-to-native leaflet structure without foreign body response.ConclusionsECM tricuspid tube grafts were stronger than native leaflet tissue. Histologically, the acellular ECM tube grafts showed evidence of constructive tissue remodeling with endothelialization and connective tissue organization. These findings support the concept of tissue engineering and recellularization, which are prerequisites for growth.     

Interactions between gnathiid isopods,cleaner fish and other fishes on Lizard Island,Great Barrier Reef

The rate of emergence of micropredatory gnathiid isopods from the benthos, the proportion of emerging gnathiids potentially eaten by Labroides dimidiatus, and the volume of blood that gnathiids potentially remove from fishes (using gnathiid gut volume) were determined. The abundance (mean ±s.e .) of emerging gnathiids was 41·7 ± 6·9 m^?2 day^?1 and 4552 ± 2632 reef^?1 day^?1 (reefs 91–125 m²). The abundance of emerging gnathiids per fish on the reef was 4·9 ± 0·8 day^?1; but excluding the rarely infested pomacentrid fishes, it was 20·9 ± 3·8 day^?1. The abundance of emerging gnathiids per patch reef was 66 ± 17% of the number of gnathiids that all adult L. dimidiatus per reef eat daily while engaged in cleaning behaviour. If all infesting gnathiids subsequently fed on fish blood, their total gut volume per reef area would be 17·4 ± 5·6 mm³ m^?2 day^?1; and per fish on the reefs, it would be 2·3 ± 0·5 mm^?3 fish^?1 day^?1 and 10·3 ± 3·1 mm³ fish^?1 day^?1 (excluding pomacentrids). The total gut volume of gnathiids infesting caged (137 mm standard length, L_S) and removed from wild (100–150 mm L_S) Hemigymnus melapterus by L. dimidiatus was 26·4 ± 24·6 mm³ day^?1 and 53·0 ± 9·6 mm³ day^?1, respectively. Using H. melapterus (137 mm L_S, 83 g) as a model, gnathiids had the potential to remove, 0·07, 0·32, 0·82 and 1·63% of the total blood volume per day of each fish, excluding pomacentrids, caged H. melapterus and wild H. melapterus, respectively. In contrast, emerging gnathiids had the potential of removing 155% of the total blood volume of Acanthochromis polyacanthus (10·7 mm L_S, 0·038 g) juveniles. That L. dimidiatus eat more gnathiids per reef daily than were sampled with emergence traps suggests that cleaner fishes are an important source of mortality for gnathiids. Although the proportion of the total blood volume of fishes potentially removed by blood‐feeding gnathiids on a daily basis appeared to be low for fishes weighing 83 g, the cumulative effects of repeated infections on the health of such fish remains unknown; attacks on small juvenile fishes, may result in possibly lethal levels of blood loss.     

Seasonal variation in steroid hormones and blood parameters in cage-farmed European sea bass (Dicentrarchus labrax L.)

For a period of 1 year, some blood parameters were evaluated on a monthly basis in a population of adult European sea bass (Dicentrarchus labrax L.) intensively reared in floating marine cages (Ionian Sea, Mediterranean). From April (13 months old) to July (16 months old) males (35–50%) and sexually indeterminate individuals were collected. From August to March (24 months old) only males were sampled. During this period the percentage of spermiated males was highest (100%) from November (20 months old) to January (22 months old). Plasma testosterone in males was inversely related to sunlight (h month^?1) and was elevated between October and January, when males first achieved sexual maturity. Testosterone showed the highest value (0.49 ± 0.02 ng ml^?1) in January and the lowest (0.09 ± 0.02 ng ml^?1) in March. Haematocrit, red blood cell counts and haemoglobin concentration were elevated from November to March, being inversely related to sunlight. The two latter parameters were also inversely related to daily food intake. Haematocrit, red blood cell counts and haemoglobin concentration were highest in December [53 ± 1%, (5.36 ± 0.06) × 10⁶ mm^?3, 10.08 ± 0.14 g 100 ml^?1, respectively] and lowest in June [35 ± 1%, (3.33 ± 0.05) × 10⁶ mm^?3, 6.47 ± 0.13 g 100 ml^?1, respectively]. White blood cell counts were not correlated with sea water temperature, sunlight or daily food intake. They were highest in February [(8.45 ± 0.20) × 10⁴ mm^?3] and lowest in April [(6.07 ± 0.14) × 10⁴ mm^?3]. Total plasma protein concentration (4.88 ± 0.11–5.93 ± 0.10 g 100 ml^?1) and mean cell volume (93.3 ± 0.9–105.5 ± 1.8 μm³) showed small fluctuations throughout the year. Sexual maturity appears to be a major factor that significantly affects haemopoiesis of D. labrax. This study contributes to the evaluation of normal levels of some blood parameters in European sea bass, which are helpful for the assessment of physiological status and health of this species.     

The volume and area of the capillaries in the endocrine and exocrine pancreas of the rat

Summary The capillary volumes in the endocrine and exocrine parenchyma of the pancreas were compared with a point-sampling technique. The islets were found to have a capillary volume of approximately 3.5%, while the value for the exocrine pancreas was significantly (P<0.001) lower at 2%. When the capillary wall area was measured, however, both types of parenchyma had a similar value of approximately 20 mm²/mm³ tissue. The reason for the discrepancy between these parameters is probably the lack of lymphatic capillarics, with their relatively small lumen in the islets.     

Intra-arterial administration of tumor-targeting Salmonella typhimurium A1-R regresses a cisplatin-resistant relapsed osteosarcoma in a patient-derived orthotopic xenograft (PDOX) mouse model

Previously, a patient-derived orthotopic xenograft (PDOX) model was established with a lung metastasis from an osteosarcoma patient which developed after adjuvant cisplatinum (CDDP) treatment. In this model, we previously demonstrated the efficacy of trabectedin (TRAB) and temozolomide (TEM) compared with CDDP. In the present report, osteosarcoma tissue was implanted orthotopically in the distal femur of mice which were randomized into the following groups when tumor volume reached approximately 100 mm³; On day 14 after initiation of treatment, all but CDDP significantly inhibited tumor volume growth compared with untreated controls. Control (G1): 793.7 ± 215.0 mm³; CDDP (G2): 588.1 ± 176.9 mm³; Salmonella typhimurium A1-R (S. typhimurium A1-R) intravenous (i.v.) (G3): 269.7 ± 72.7 mm³; S. typhimurium A1-R intra-arterial (i.a.) (G4): 70.2 ± 18.9 mm³ (CDDP: p = 0.056; S. typhimurium A1-R i.v.: p = 0.0001; S. typhimurium A1-R i.a.: p = 0.00003, all vs. untreated controls). i.a. administration of S. typhimurium A1-R was significantly more effective than either CDDP (p = 0.00007), or i.v. administration of S. typhimurium A1-R (p = 0.00007) and significantly regressed the tumor volume compared with day 0 (p = 0.001). The new model of i.a. administration of S. typhimurium A1-R has great promise for the treatment of recalcitrant osteosarcoma.     

Exacerbation of NMDA, AMPA, and l-Glutamate Excitotoxicity by the Succinate Dehydrogenase Inhibitor Malonate

Abstract: We report that a subtoxic dose of the succinate dehydrogenase (SDH) inhibitor malonate greatly enhances the neurotoxicity of three different excitatory amino acid agonists: N-methyl-d -aspartate (NMDA), S-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (S-AMPA), and l -glutamate. In male Sprague-Dawley rats, intrastriatal stereotaxic injection of malonate alone (0.6 µmol), NMDA alone (15 nmol), S-AMPA alone (1 nmol), or glutamate alone (0.6 µmol) produced negligible toxicity as assessed by measurement of lesion volume. Coinjection of subtoxic malonate with NMDA produced a large lesion (15.2 ± 1.4 mm³), as did coinjection of malonate with S-AMPA (11.0 ± 1.0 mm³) or glutamate (12.8 ± 0.7 mm³). Administration of the noncompetitive NMDA antagonist MK-801 (5 mg/kg i.p.) completely blocked the toxicity of malonate plus NMDA (0.5 ± 0.3 mm³). This dose of MK-801 had little effect on the lesion produced by malonate plus S-AMPA (9.0 ± 0.7 mm³), but it attenuated the toxicity of malonate plus glutamate by ～40% (7.5 ± 0.9 mm³). Coinjection of the AMPA antagonist 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo(f)-quinoxaline (NBQX; 2 nmol) had no effect on malonate plus NMDA or malonate plus glutamate toxicity (12.3 ± 1.8 and 14.0 ± 0.9 mm³, respectively) but greatly attenuated malonate plus S-AMPA toxicity (1.5 ± 0.9 mm³). Combination of the two antagonists conferred no additional neuroprotection in any paradigm. These results indicate that metabolic inhibition exacerbates both NMDA receptor- and non-NMDA receptor-mediated excitotoxicity. They also suggest that the NMDA receptor may play a major role in situations of metabolic compromise in vivo, where glutamate is the endogenous agonist. Furthermore, glutamate toxicity under conditions of metabolic compromise may not be mediated entirely by ionotropic glutamate receptors.     

Muscle capillary supply in hind limb and diaphragm of the common shrew (Sorex araneus)

Shrew species of the subfamily Soricinae have unusually high metabolic rates when compared to Crocidurinae shrews and other similar-sized mammals. The aim of this study was to clarify whether the high basal metabolic rate of Soricinae shrews is reflected in a high capillary density in their muscles. To this end, the capillary supply of four limb muscles and diaphragm of the common shrew (Sorex araneus) was quantified from cross-sectioned muscles. The capillary densities of the limb muscles were 2575 ± 329, 3111 ± 299, 2812 ± 197 and 2752 ± 173 capillaries mm⁻² fibre area in gastrocnemius lateralis, g. medialis, plantaris and soleus, respectively. Capillary density of the shrew diaphragm (6691 ± 1057) was double that of the limb muscles. This value is among the highest ever measured in mammals. In general, the capillary supply in the hind limb of the common shrew is about 3–4 times higher than commonly found in the leg muscles of the laboratory rat or other bigger mammals, but similar to those in Crocidurinae shrews and some small rodents. Thus the high resting metabolism of the common shrew is not associated with an extraordinarily high capillary density. The apparent disparity between basal metabolic rate and muscle capillary supply in S. araneus is probably due to the small aerobic scope of shrews in the subfamily Soricinae. Accepted: 22 January 1998     

Protein content and volume of early porcine blastocysts

Mean protein and volume of 222 blastocysts collected on 6 to 9 days of pregnancy were measured. Embryo protein differed (P < 0.05) for each day of development studied. Protein content of embryos doubled between days 6 and 7 and days 7 and 8 (1.2 ± 0.04, 2.0 ± 0.14, and 3.7 ± 0.2 μg, respectively). A dramatic increase from 3.7 ± 0.2 to 56.0 ± 3.4 μg was observed between days 8 and 9. Blastocyst volume increased (P < 0.05) from 0.56 ± 0.03 × 10^?2mm³ to 1.11 ± 0.04 × 10^?2mm³ between days 6 and 7, and then increased 10-fold on day 8 and five-fold on day 9. Blastocyst volume was not correlated with protein for days of development and females studied. Approximately 20% of all blastocysts within a single female contained less protein than the average protein content of all embryos from the same uterus. The results indicate that day 6 of development marks the onset of an exponential increase in embryo protein. Also, blastocyst volume is not correlated with blastocyst protein, suggesting that embryo viability is difficult to estimate by size alone. Further, approximately 20% of the blastocysts collected from a single female may exhibit reduced viability, based on reduced protein content, as early as day 6 of development.     

Characterizing Photothrombotic Distal Middle Cerebral Artery Occlusion and YAG Laser-Induced Reperfusion Model in the Izumo Strain of Spontaneously Hypertensive Rats

No study has systematically studied the relevance of original Izumo strain of spontaneously hypertensive rats (SHR/Izm) as a stroke model. Furthermore, both SHR/Izm and stroke-prone SHR/Izm (SHRSP/Izm) are commercially available, and recent progress in genetic studies allowed us to use several congenic strains of rats constructed with SHR/Izm and SHRSP/Izm as the genetic background strains. A total of 166 male SHR/Izm and 17 male SHRSP/Izm were subjected to photothrombotic middle cerebral artery (MCA) occlusion with or without YAG laser-induced reperfusion. The pattern of distal MCA was recorded. Infarct volumes were determined with 2,3,5-triphenyltetrazolium chloride. At 24 or 48 h after MCA occlusion, infarct volumes in the permanent occlusion and 2-h occlusion groups (88 ± 22 [SD] and 87 ± 25 mm³, respectively) were significantly larger than that in the 1-h occlusion group (45 ± 14 mm³), indicating the presence of sizeable zone of penumbra. Infarct size in SHRSP/Izm determined at 24 h after MCA occlusion was fairly large (124.0 ± 34.8 mm³, n = 10). Infarct volume in SHR/Izm with simple distal MCA was 76 ± 19 mm³, which was significantly smaller than 95 ± 22 mm³ in the other SHR/Izm with more branching MCA. These data suggest that this stroke model in SHR/Izm is useful in the preclinical testing of stroke therapies and elucidating the pathophysiology of cerebral ischemia/reperfusion.     

Irradiation to the immature brain attenuates neurogenesis and exacerbates subsequent hypoxic‐ischemic brain injury in the adult

Cranial radiotherapy is common in pediatric oncology. Our purpose was to investigate if irradiation (IR) to the immature brain would increase the susceptibility to hypoxic‐ischemic injury in adulthood. The left hemisphere of postnatal day 10 (P10) mice was irradiated with 8 Gy and subjected to hypoxia‐ischemia (HI) on P60. Brain injury, neurogenesis and inflammation were evaluated 30 days after HI. IR alone caused significant hemispheric tissue loss, or lack of growth (2.8 ± 0.42 mm³, p < 0.001). Tissue loss after HI (18.2 ± 5.8 mm³, p < 0.05) was synergistically increased if preceded by IR (32.0 ± 3.5 mm³, p < 0.05). Infarct volume (5.1 ± 1.6 mm³) nearly doubled if HI was preceded by IR (9.8 ± 1.2 mm³, p < 0.05). Pathological scoring revealed that IR aggravated hippocampal, cortical and striatal, but not thalamic, injury. Hippocampal neurogenesis decreased > 50% after IR but was unchanged by HI alone. The number of newly formed microglia was three times higher after IR + HI than after HI alone. In summary, IR to the immature brain produced long‐lasting changes, including decreased hippocampal neurogenesis, subsequently rendering the adult brain more susceptible to HI, resulting in larger infarcts, increased hemispheric tissue loss and more inflammation than in non‐irradiated brains.     

A method for separate quantitative determination of 2-keto-3-deoxy-octonate and 3,6-dideoxyhexoses in mixtures.

A method for analysing ³²P in small aqueous samples by measuring the ?erenkov radiation is described. Centering problems with small sample volumes are eliminated by placing the sample in a polystyrene tube in the scintillation vial. The detection efficiency is high, 54.5 ± 0.6% (2 SD) at a sample volume of 25 μl. The reproducibility is good and independent of the sample volume. The detection efficiency of ³²P in polyacrylamide gel is shown to be as good as in water.     

THE CELL PROLIFERATION KINETICS OF THE EMT6/M/AC MOUSE TUMOUR AT FOUR VOLUMES DURING UNPERTURBED GROWTH IN VIVO

The cell proliferation kinetics of the EMT6/M/AC mouse tumour were determined at four different volumes between 1–5 mm³ and 175 mm³. The decrease in the growth rate between these volumes was mainly due to a decrease in the rate constant for cell production. A small increase in the rate constant for cell loss occurred, but this was thought to be insignificant. The cell loss factor increased from 40% at 1–5 mm³ to over 70% in the 175 mm³ tumours. An increase in the median cell cycle time, from 14-1 hr to 18-5 hr was also found between these same volumes. Results obtained for the NCTC fibrosarcoma and the R-l rhabdomyosarcoma indicate that there may be a threshold volume in these sarcomas below which little or no cell loss takes place. This was not found in the EMT6/ M/AC tumour.     

Spatiotemporal Optoacoustic Mapping of Tumor Hemodynamics in a Clinically Relevant Orthotopic Rabbit Model of Head and Neck Cancer

The purpose of this study was to investigate the usefulness of photoacoustic imaging (PAI) for spatiotemporal mapping of tumor hemodynamics in a rabbit model of head and neck carcinoma. Shope cottontail rabbit papilloma virus associated VX2 carcinomas were established in adult male New Zealand White rabbits (n = 9) by surgical transplantation of tumor tissue in the neck. Noninvasive PAI with co-registered ultrasound (US) was performed to longitudinally monitor tumor growth, oxygen saturation (%sO₂), and hemoglobin concentration (HbT). PAI findings were validated with Doppler sonography measures of percent vascularity (PV). Differences in tumor volumes, %sO₂, HbT, and PV values over time were analyzed using repeated-measures analysis of variance with multiple comparisons. Two-tailed Spearman correlation analysis was performed to determine the correlation coefficient (r) for comparisons between %sO₂, HbT, and tumor volume. US revealed a significant (P < .0001) increase in tumor volume over the 3-week period from 549 ± 260 mm³ on day 7 to 5055 ± 438 mm³ at 21 days postimplantation. Consistent with this aggressive tumor growth, PAI revealed a significant (P < .05) and progressive reduction in %sO₂ from day 7 (37.6 ± 7.4%) to day 21 (9.5 ± 2.1%). Corresponding Doppler images also showed a decrease in PV over time. PAI revealed considerable intratumoral spatial heterogeneity with the tumor rim showing two- to three-fold higher %sO₂ values compared to the core. Noninvasive PAI based on endogenous contrast provides a label-free method for longitudinal monitoring of temporal changes and spatial heterogeneity in thick head and neck tumors.     

Embryonic stroke volume and cardiac output in the chick

Cine recordings of the hearts of chick embryos of 3 days and 2 hr to 4 days and 21 hr incubation were projected and measured. The measurements were converted to volumes. Stroke volume was determined from the difference in end diastolic and end systolic volume and multiplied by heart rate to yield cardiac output. Mean stroke volume was 0.0058 (±0.00036 SEM) mm³ per mg body wt; mean cardiac output was 0.956 (± 0.061 SEM) mm³/min per mg body wt. Stroke volume and cardiac output rose above their control values after intravascular injection of Ringer's solution, and even more so after the injection of dextran solution. The increases in stroke volume were due to increases in end diastolic volume, in the case of dextran injected embryos they occurred in spite of a simultaneous increase in end systolic volume. It is concluded that the rise in cardiac output with growth of the embryo is in large part due to an increase in stroke volume, and that the increase in stroke volume depends in part on the known increase in embryonic blood volume. The experiments further suggest that a rapid hydrostatic and osmotic equilibrium exists between embryonic blood plasma and an extra vascular compartment.     

Leaf and green stem anatomy of the drought deciduous Mediterranean shrub Calicotome villosa (Poiret) Link. (Leguminosae)

Light and scanning electron microscopy were used to study leaf and stem fine structure of the drought deciduous green-stemmed Mediterranean shrub Calicotome villosa (Poiret) Link. (Leguminosae). Each leaf consists of three small obovate leaflets with abundant but small (16 μm length) anomocytic stomata on both surfaces. Adaxial surface exhibits more than double stomatal density (440±8 mm⁻²) than the abaxial one (185±4 mm⁻²). T-shaped trichomes (36±3 mm⁻²) are present only on the abaxial leaf surface. Leaves are unifacial, furnished with palisade parenchyma on both sides. The stem is characterized by raised ridges and grooves. Beneath the one-cell-layered epidermis sclerenchyma is found on ridges, whereas stomata and palisade chlorenchyma are found in grooves. Hairs are abundant, especially in grooves. Stem and leaf palisade chlorenchymas are structurally similar. According to these data, photosynthesis could be efficiently supported by the stem.     

MC4R Variant Is Associated With BMI but Not Response to Resistance Training in Young Females

Recently, a genome‐wide association study (GWAS) that identified eight single‐nucleotide polymorphisms (SNPs) associated with BMI highlighted a possible neuronal influence on the development of obesity. We hypothesized these SNPs would govern the response of BMI and subcutaneous fat to resistance training in young individuals (age = 24 years). We genotyped the eight GWAS‐identified SNPs in the article by Willer et al. in a cohort (n = 796) that undertook a 12‐week resistance‐training program. Females with a copy of the rare allele (C) for rs17782313 (MC4R) had significantly higher BMIs (CC/CT: n = 174; 24.70 ± 0.33 kg/m², TT: n = 278; 23.41 ± 0.26 kg/m², P = 0.002), and the SNP explained 1.9% of overall variation in BMI. Males with a copy of the rare allele (T) for rs6548238 (TMEM18) had lower amounts of subcutaneous fat pretraining (CT/TT: n = 65; 156,534 ± 7,415 mm³, CC: n = 136; 177,825 ± 5,139 mm³, P = 0.019) and males with a copy of the rare allele (A) for rs9939609 (FTO) lost a significant amount of subcutaneous fat with exercise (AT/AA: n = 83; ?798.35 ± 2,624.30 mm³, TT: n = 47; 9,435.23 ± 3,494.44 mm³, P = 0.021). Females with a copy of the G allele for a missense variant in the SH2B1 (rs7498665) was associated with less change of subcutaneous fat volume with exercise (AG/GG: n = 191; 9,813 ± 2,250 mm³ vs. AA: n = 126; 770 ± 2,772 mm³; P = 0.011). These data support the original finding that there is an association between measures of obesity and a variant near the MC4R gene and extends these results to a younger population and implicates FTO, TMEM18, and SH2B1 polymorphisms in subcutaneous fat regulation.     

CYTOKINETICS OF TUMOUR AND ENDOTHELIAL CELLS AND VASCULARIZATION OF LUNG METASTASES IN C3H/HE MICE

A model of lung metastases was developed using intravenous injection of tumour cell aggregates of spontaneous C3H/He mammary tumours in syngeneic mice. the growth rate of lung tumours decreased with increasing tumour volume, with mean host survival of 46 days. the cytokinetics of individual tumours ranging between 0.004 and 4.2 mm³ in volume were studied. the labelling index (LI) ranged between 12 and 17%, the DNA synthesis time (T_s) being 9–10 hr. the growth fraction (GF) ranged between 26 and 38%. the cell cycle time (T_c) was found to be 18–19 hr. the LI and the GF decreased with increasing tumour volume doubling time (T_d). No correlation was found between the tumour volume and T_c. the LI of endothelial cells within these tumours, ranging between 0.004 and 4.2 mm³ in volume was 14–15% and endothelial cell proliferation was not affected by tumour growth. Vascular parameters were also determined for these tumours as a function of tumour volume. Vascular volume increased with increasing tumour size while the percentage of capillary vessels decreased. the cellular volume to capillary volume ratio increased with increasing tumour volume. Necrosis was observed in 0.27 mm³ tumours and increased with increasing tumour size. The results from these studies suggested that the age-dependent decrease in proliferative activity of tumour cells growing in the lung is related to change in effective vascularity.     

新型可降解锌合金内固定系统用于犬下颌骨骨折固定的研究

目的:探讨新型可降解锌合金内固定系统用于犬下颌骨骨折固定的可行性。方法:选择比格犬12只,并将其随机分为两组,其中6只为锌合金实验组,6只为钛合金对照组。每只比格犬的下颌作左右两个骨折内固定模型,每侧骨折模型使用一套小型四孔直连内固定产品。分别于术后即刻、术后4周、12周拍X片。于术前、术后4周、12周、24周抽血检测微量元素锌。于术后12周、24周分批次将动物安乐死,取下颌骨块行Micro-CT检测,取动物重要脏器和内固定周围软组织做病理切片。结果:全程动物无脱落,实验组与对照组骨折均临床愈合。X线图像及Micro-CT显示实验组与对照组的内固定效果比较差异无统计学意义(P0.05)。锌合金表面有明显的降解产物,Micro-CT测量锌合金的板钉初始体积为155.8±1.536 mm~3,12周体积为147.1±0.9893 mm~3,24周体积为137±5.365 mm~3,降解率12.07%,随着植入后时间的延长显著下降(P0.05),而钛合金板钉体积无显著变化。实验组及对照组心、肝、肾及植入物板周软组织均未见异常。血清锌离子浓度在正常范围内略有上升,各时间节点比较差异无统计学意义(P0.05)。结论:可降解锌合金内固定系统可以对犬下颌骨骨折提供稳固的固定,可降解锌合金在下颌骨部位具有一定的降解性能,血液中锌离子未见明显异常升高,对心、肝、肾及植入物周围软组织无毒性作用。     

Renal vasculature and uriniferous tubules in the common iguana

The pattern of vascular supply and the histology of uriniferous tubules of the kidney in the common iguana were studied by light microscopy of semithin sections and by scanning electron microscopy of microcorrosion casts. The corrosion casts showed a strongly developed renal portal system that forms an extensive capillary network throughout the kidney. Glomeruli are numerous and have a capillary pattern consisting of three to six loose coils of capillaries intercalated between afferent and efferent arterioles. Glomeruli are ovoid in shape and relatively small (mean diameter of the casts: 67 ± 19 μm in short axis and 79 ± 18 μm in long axis). Each glomerulus has a single afferent arteriole and efferent arteriole. The length and volume of the glomerular capillaries per unit volume of renal corpuscle are 0.0029 ± 0.0008 μm/μm³ and 0.321 ± 0.077, respectively. A short neck segment consisting of low epithelial cells is interposed between Bowman's capsule and the proximal tubule. A close association between the distal tubule and the glomerular hilus can be interpreted as a juxtaglomerular apparatus. © 1996 Wiley-Liss, Inc.