Serum Levels of Calcitonin Gene-Related Peptide and Substance P are Decreased in Patients with Diabetes Mellitus and Coronary Artery Disease

OBJECTIVE: This study evaluated serum levels of the neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP) in coronary artery disease (CAD) patients with and without a history of diabetes mellitus (DM). METHODS: Patients undergoing coronary angiography for suspected myocardial ischaemia were divided into four groups depending on their clinical status: control group (no CAD or DM; n = 44), DM group (DM without CAD; n = 46), CAD group (stable CAD without DM; n = 44) and DM + CAD group (stable CAD with DM; n = 50). Serum levels of CGRP and SP were determined using radioimmunoassays. RESULTS: CGRP and SP levels in the DM and CAD groups were significantly lower than in the control group. The lowest levels of CGRP and SP were observed in the DM + CAD group. There were no significant differences in CGRP and SP levels between the DM group and the CAD group. CONCLUSION: CGRP and SP may have a role in the pathogenesis of CAD in patients with diabetes.

Algorithm for automatic detection of pentylenetetrazole-induced seizures in rats

Epilepsy affects approximately one percent of the world population. Antiepileptic drugs are ineffective in approximately 30% of patients and have side effects. We are developing a noninvasive, or minimally invasive, transcranial focal electrical stimulation (TFS) system through our novel concentric ring electrodes to control seizures. Here we report on the development of a seizure detecting algorithm to be used for automatic application of TFS. A cumulative sum (CUSUM) algorithm was evaluated that detected the electrographic seizure activity in all experiments well in advance of the behavioral seizure activity.

Isolation, sequence analysis, and characterization of androgen receptor in Southern catfish, Silurus meridionalis

Androgen receptor (AR), the mediator of androgen, plays important roles in the androgen signal pathway. In the present study, we isolated and analyzed the cDNA sequence and tissue distribution of androgen receptor in Southern catfish (scAR). The full-length cDNA of scAR contains 3,116 bp with an open reading frame (ORF) of 2,415 bp, encoding a protein of 804 amino acids (aa). Tissue distribution analysis of scAR revealed that it was expressed in all tissues examined, with no sexual dimorphism in the ovary and testis. Phylogenetic analysis and multiple amino acids sequence alignment indicated the close relationship and high similarity of scAR with ARs from cypriniform species. In addition, partial sequences of ARs from 7 other siluriform species were also isolated. Comparison of catfish ARs with those from other vertebrates revealed that an extra C-terminal tail of about 20aa exists in all the ARs from siluriform fishes investigated, but not in other ARs. The extra sequence was resulted from a 4-bp insertion before the stop codon of other vertebrate ARs, and it was identical in ARs from siluriform species of the same genus but different among ARs from species of different genera. We report here for the first time that the ARs from siluriform species are longer in C-terminal than those from other vertebrates and it might be useful in reconstruction of the phylogenetic relationship among siluriform fishes. The significance of the extra C-terminal tail for AR function remains elusive.

Tendon fascicle gliding in wild type, heterozygous, and lubricin knockout mice

The objective of this study was to investigate the role of lubricin in the lubrication of tendon fascicles. Lubricin, a glycoprotein, lubricates cartilage and tendon surfaces, but the function of lubricin within the tendon fascicle is unclear. We developed a novel method to assess the gliding resistance of a single fascicle in a mouse tail model and used it to test the hypothesis that gliding resistance would be increased in lubricin knockout mice. Thirty-six mouse tails were used from 12 wild type, 12 heterozygous, and 12 lubricin knockout mice. A 15 mm long fascicle segment was pulled proximally after being divided distally. The peak resistance during fascicle pullout and the fascicle perimeter were measured. Lubricin expression was evaluated by immunohistochemistry. The peak gliding resistance in the lubricin knockout mice was significantly higher than in the wild type (p < 0.05). Fascicles from heterozygous mice were intermediate in value, but not significantly different from either wild type or lubricin knockout fascicles in peak gliding resistance. No significant difference was found in fascicle perimeter among the three groups. No correlation was observed between fascicle perimeter and gliding resistance. While lubricin was detected by immunostaining on the fascicle surface in wild type and heterozygous mice, lubricin was not detectable in the tendons of knockout mice. We conclude that the absence of lubricin is associated with increased interfascicular friction and that lubricin may play an important role in interfascicular lubrication.

Application of carbodiimide derivatized synovial fluid to enhance extrasynovial tendon gliding ability

PURPOSE

To investigate the effects of surface modification of extrasynovial tendon with a carbodiimide derivatized synovial fluid (SF) on the gliding ability of extrasynovial tendon for a possible tendon graft application.

METHODS

We used 63 peroneus longus tendons from canine hind legs. We immediately assessed 3 tendons morphologically using a scanning electron microscope (SEM); these served as the normal tendon group. The other 60 tendons were randomly assigned to each of 6 experimental groups treated with (1) control (saline); (2) 1% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) plus 1% N-hydroxysuccinimide (NHS) (cd only); (3) 1% EDC/NHS plus 10% gelatin (cd-G); (4) SF plus 1% EDC/NHS plus 10% gelatin (cd-SF-G); (5) SF only; or (6) SF plus 1% EDC/NHS (cd-SF). We measured the gliding resistance for 1,000 cycles of simulated flexion-extension motion. We also observed the tendon surface smoothness by SEM.

RESULTS

Compared with the first cycle in each group, the gliding resistance after 1,000 cycles of tendon motion was significantly increased in the control, cd only, cd-gelatin, SF only, and cd-SF groups (p<.05). In contrast, we found no significant difference in gliding resistance between the first cycle and 1,000 cycles for the cd-SF-G-treated group. In addition, the gliding resistance in the cd-SF, cd-G, and cd-SF-G groups was significantly lower than the control group after 1,000 cycles of tendon motion (p<.05) and the gliding resistance of the cd-SF-G group was significantly lower than both the cd-G and cd-SF groups (p<.05). On SEM, the surface treated with cd-SF-G was smooth after 1,000 cycles, whereas the other surfaces were rough.

CONCLUSIONS

Surface modification of extrasynovial tendon with cd-SF-G improves tendon gliding ability. This treatment may be useful clinically in improving the outcomes of tendon autografts.

Improvement of flexor tendon reconstruction with carbodiimide-derivatized hyaluronic acid and gelatin-modified intrasynovial allografts: study of a primary repair failure model

BACKGROUND

Tendon grafts play an important role in flexor tendon reconstruction. This study was an investigation of the effects of surface modification of allograft intrasynovial tendons with carbodiimide-derivatized hyaluronic acid and gelatin in an in vivo canine model. To mimic the actual clinical situation, a novel and clinically relevant model of a failed primary flexor tendon repair was used to evaluate the flexor tendon grafts.

METHODS

Twenty-eight flexor digitorum profundus tendons from the second and fifth digits of fourteen dogs were lacerated and repaired in zone II in a first-surgery phase. The dogs were allowed free active motion postoperatively. In a second phase, six weeks later, the tendons were reconstructed with use of a flexor digitorum profundus allograft. In each dog, one graft was treated with carbodiimide-derivatized hyaluronic acid and gelatin (the CHG group) and the other was treated with saline solution, as a control. The dogs were restricted from free active motion, but daily therapy was performed beginning on postoperative day 5 and continued until six weeks after the operation, when the animals were killed. The outcomes were evaluated on the basis of digit work of flexion, gliding resistance, healing at the distal attachment, graft cell viability, histological findings, and findings on scanning electron microscopy.

RESULTS

In the first phase, all twenty-eight repaired tendons ruptured, with scar and adhesion formation in the repair site. Six weeks after allograft reconstruction, the mean work of flexion was 0.37 and 0.94 N-mm/degree in the CHG group and the saline-solution control group, respectively; these values were significantly different (p < 0.05). The gliding resistance in the CHG group was also significantly less than that in the saline-solution control group (0.18 versus 0.28 N) (p < 0.05), but no difference between groups was observed with regard to the distal tendon-bone pullout strength. Histological analysis showed that tenocytes in the host tendon proliferated and migrated toward the acellular allograft.

CONCLUSIONS

This primary repair failure model was reproducible and reliable, with a uniform failure pattern, and provides an appropriate and clinically relevant animal model with which to study flexor tendon reconstruction. The surface modification of allografts with carbodiimide-derivatized hyaluronic acid and gelatin improved digital function and tendon gliding ability.

Temporal response of canine flexor tendon to limb suspension

Tendon disuse, or stress deprivation, frequently accompanies clinical disorders and treatments, yet the metabolism of tendons subject to stress deprivation has rarely been investigated systematically. The effects of stress deprivation on canine flexor tendon were investigated in this study. One adult canine forepaw was suspended for 21 or 42 days. Control forepaws were collected from dogs that had no intervention on their limbs and paws. The expression of collagen I and III was not significantly altered in the tendons disused for 21 days but was significantly decreased at 42 days (P < 0.03). The expression of collagen II, aggrecan, decorin, and fibronectin was significantly decreased in the tendons in the suspended limbs at 21 days (P < 0.002) and further reduced at 42 days. With stress deprivation, the expression of matrix metalloproteinase 2 (MMP2) was significantly increased (P < 0.004) at 21 and 42 days. The expression of MMP3 was significantly decreased at 21 and 42 days (P < 0.03). The expression of MMP13 was not altered with stress deprivation at 21 and 42 days. The expression of MMP14 was significantly increased at 21 days (P = 0.0015) and returned to the control level at 42 days. Tissue inhibitor of metalloproteinase 1 (TIMP1) expression was decreased after the limbs were suspended for 42 days (P = 0.0043), but not 21 days. However, TIMP2 expression was not significantly different from control at 21 or 42 days. Furthermore, the cross-sectional area of the stress-deprived tendons at 42 days was decreased compared with the control group (P < 0.01). The intervention method in this study did not result in any alteration of stiffness of the tendon. Our study demonstrated that stress deprivation decreases the anabolic process and increases the catabolic process of extracellular matrix in flexor tendon.

Effects of a lubricin-containing compound on the results of flexor tendon repair in a canine model in vivo

BACKGROUND

Tendon surface modification with a synthetic biopolymer, carbodiimide-derivatized hyaluronic acid and gelatin with the addition of lubricin (CHL), has been shown to reduce gliding resistance after tendon repair in an in vitro model. The purpose of the study was to investigate whether CHL would reduce adhesion formation and improve digital function after flexor tendon repair in a canine model in vivo.

METHODS

Sixty dogs were randomly assigned to either a biopolymer-treated group (n = 30) or an untreated control group (n = 30). The second and fifth flexor digitorum profundus tendons from each dog were lacerated fully at the zone-II area and then repaired. Passive synergistic motion therapy was started on the fifth postoperative day and continued until the dogs were killed on day 10, day 21, or day 42. The repaired tendons were evaluated for adhesions, normalized work of flexion, gliding resistance, repair strength, stiffness, and histological characteristics.

RESULTS

The normalized work of flexion of the repaired tendons treated with CHL was significantly lower than that of the non-CHL-treated repaired tendons at all time points (p < 0.05), and the prevalence of severe adhesions was also significantly decreased in the CHL-treated tendons at day 42 (p < 0.05). However, the repair failure strength and stiffness of the CHL-treated group were also significantly reduced compared with those of the control group at days 21 and 42 (p < 0.05) and the rate of tendon rupture was significantly higher in the treated group than in the control group at day 42 (p < 0.05).

CONCLUSIONS

Treatment with the lubricin-containing gel CHL appears to be an effective means of decreasing postoperative flexor tendon adhesions, but it is also associated with some impairment of tendon healing. Future studies will be necessary to determine if the positive effects of CHL on adhesion formation can be maintained while reducing its adverse effect on the structural integrity of the repaired tendon.

Enhancement of dopamine sensing by layer-by-layer assembly of PVI-dmeOs and Nafion on carbon nanotubes

In this study, carbon nanotubes (CNTs) were modified to further improve their performance in electrochemical sensing of dopamine (DA) levels. After a redox polymer, poly(vinylimidazole) complexed with Os(4, 4'-dimethyl- 2, 2-bipyridine)(2)Cl (termed PVI-dmeOs) was electrodeposited on multi-wall CNTs (MWCNTs), Nafion and PVI-dmeOs films were successfully layer-by-layer (LBL) assembled on the hydrophilic surface of the as-prepared PVI-dmeOs/CNTs nanocomposites through electrostatic interactions. The LBL assembly was proved by scanning electron microscopy (SEM), electrochemistry and UV-vis spectroscopy measurements. LBL assembly of Nafion/PVI-dmeOs films on CNTs significantly enhanced their linear sweep voltammetry (LSV) response sensitivity to DA, with a maximum enhancement for three Nafion/PVI-dmeOs film-modified MWCNTs. The LSV peak current density of (Nafion/PV I-dmeOs)(3)/CNT electrodes in response to 10 and 50 microM DA solutions was about 7.3 and 3.9 times those for bare CNTs. At the (Nafion/PV I-dmeOs)(3)/CNT electrodes, the limit of detection (LOD) (signal-to-noise ratio: 3) was 0.05 microM DA, the linear range was 0.1-10 microM DA (with a linear regression coefficient of 0.97) and the DA-sensing sensitivity was 8.15 microA cm( - 2) microM( - 1). The newly fabricated (Nafion/PV I-dmeOs)(3)/CNT electrodes may be developed as an ideal biosensor for direct and in situ measurement of DA levels.

Carbodiimide-derivatized hyaluronic acid surface modification of lyophilized flexor tendon: a biomechanical study in a canine in vitro model

BACKGROUND

Intrasynovial grafts are the ideal solution to replace defects in intrasynovial flexor tendons, but autologous graft sources are rarely available. The purpose of the present study was to test the hypotheses that an intrasynovial tendon prepared with repetitive freeze-thaw cycles and lyophilization (as a means of reducing immunogenicity) has increased frictional force (gliding resistance) in comparison with fresh intrasynovial tendons and that a lyophilized intrasynovial flexor tendon that is modified with carbodiimide-derivatized hyaluronic acid and gelatin has decreased frictional force in comparison with untreated lyophilized tendons.

METHODS

Thirty-six flexor digitorum profundus tendons from the second and fifth digits of canine hind paws were randomly assigned to three groups. Twelve tendons were immediately assessed both mechanically and morphologically and served as the normal tendon group. The other twenty-four tendons were prepared with repetitive freeze-thaw cycles and lyophilization and were randomly assigned to two groups, including one group in which the tendons were treated with carbodiimide-derivatized hyaluronic acid and gelatin and one group in which the tendons were not treated. The frictional force was measured during 1000 cycles of simulated flexion-extension motion in all tendons, and the mean frictional forces were compared. The tendons were then observed with use of transmitted light microscopy for residual hyaluronic acid on the tendon surface, and the smoothness of the surface was evaluated with use of scanning electron microscopy.

RESULTS

The frictional force after lyophilization was significantly increased by 104.9% after the first cycle and by 99.5% after 1000 cycles in comparison with the normal tendon (p < 0.05). The frictional force of the lyophilized tendons after treatment with carbodiimide-derivatized hyaluronic acid and gelatin was not significantly different from that of normal tendons. The untreated lyophilized tendon surfaces were observed on scanning electron microscopy to be rough in appearance, whereas the normal surface and the surface treated with carbodiimide-derivatized hyaluronic acid and gelatin were smooth, with residual hyaluronic acid present on the gliding surface.

CONCLUSIONS

Lyophilization alters tendon surface morphology and increases tendon frictional force. Surface modification with carbodiimide-derivatized hyaluronic acid and gelatin can mitigate this adverse effect.

CLINICAL RELEVANCE

Tendon surface modification with carbodiimide-derivatized hyaluronic acid and gelatin can improve the gliding ability of lyophilized flexor tendons and therefore may improve the utility of lyophilized tendon allografts as a tendon graft substitute.

Surface treatment with 5-fluorouracil after flexor tendon repair in a canine in vivo model

BACKGROUND

Topical 5-fluorouracil has been reported to reduce adhesions in animal models of tenolysis. The purpose of this study was to investigate the effects of topical 5-fluorouracil on adhesion formation after tendon repairs were subjected to immediate postoperative rehabilitation in a canine model in vivo.

METHODS

Sixty dogs were randomly assigned to either a 5-fluorouracil treatment (thirty dogs) or a control group (thirty dogs). Each treatment group was then divided into three survival time points: ten days, twenty-one days, and forty-two days. The second and fifth flexor digitorum profundus tendons from each dog were fully lacerated at the zone-II area and then were repaired. Passive motion therapy started at day 5 postoperatively and continued until the dogs were killed. The repaired tendons were evaluated for normalized work of flexion, gliding resistance, repair strength, gene expression for type-I and type-III collagen and transforming growth factor-beta1, and histological appearance.

RESULTS

The normalized work of flexion of the repaired tendons treated with 5-fluorouracil was significantly lower than that of the repaired tendons without 5-fluorouracil treatment at ten days. However, there was no significant difference between treated and untreated tendons at twenty-one and forty-two days. There was also no significant difference in gliding resistance, repair failure strength, or stiffness between treated and untreated tendons at any time point, or in the gross or histological appearance of adhesions at the time of killing. The expression of types-I and III collagen and transforming growth factor-beta1 of the repaired tendon with 5-fluorouracil treatment was significantly lower than that of the tendons without treatment at ten days postoperatively, but not at twenty-one or forty-two days.

CONCLUSIONS

Although 5-fluorouracil treatment can reduce adhesions in in vivo models of tenolysis, this treatment had only a transient effect in an in vivo model of tendon repair that included passive motion.

The effects of bone marrow stromal cell transplants on tendon healing in vitro

The purpose of this study was to investigate the effect of bone marrow stromal cells (BMSCs) on tendon healing in a canine ex vivo model. Bone marrow was harvested and BMSCs were isolated and cultured according to established protocols. Cells were seeded into 0.5mg/ml collagen gels and cultured for 24h to allow gel contraction, and then implanted between the lacerated ends of repaired flexor digitorum profundus tendons. Tendons repaired with a gel patch alone and without a gel patch served as control groups. After 2 and 4 weeks in culture, the repaired tendons were evaluated for breaking strength and stiffness. Cell viability was assessed by labeling the cells with PKH26 red fluorescent cell linker. The maximal strength and stiffness of repaired tendons with the BMSC-seeded patch were significantly higher than the repaired tendons without a patch or with a patch without cells, at both 2 and 4 weeks (p<0.05). Viable BMSC were present between the cut tendon ends at both 2 and 4 weeks. We conclude that BMSC-seeded gel patch transplantation has the potential to enhance flexor tendon healing, and we plan to investigate this effect in vivo.

The effect of surface treatment using hyaluronic acid and lubricin on the gliding resistance of human extrasynovial tendons in vitro

PURPOSE

To investigate the effects of tendon surface treatment using hyaluronic acid (HA) and lubricin on the gliding resistance of human extrasynovial palmaris longus (PL) tendon in vitro.

METHODS

Thirty-two fresh-frozen cadaver human fingers and 16 ipsilateral PL tendons were used. Each PL tendon was divided into 2 pieces, which were randomly assigned into 4 experimental groups. After the gliding resistance of the normal PL tendon segments were measured, the tendons were treated with either saline, carbodiimide derivatized (cd) gelatin and HA (cd-HA gelatin), cd gelatin with lubricin added (cd gelatin plus lubricin), or cd-HA gelatin plus lubricin. After treatment, tendon gliding resistance was measured during up to 1000 cycles of simulated flexion and extension motion.

RESULTS

The gliding resistance of the PL tendons in the cd-HA gelatin, cd gelatin plus lubricin, and cd-HA gelatin plus lubricin groups was significantly lower than that of the saline-treated control after 1000 cycles. The gliding resistance in these treatment groups decreased within the first 50 cycles and then increased at a much more gradual rate over the 1000 cycles, with the cd-HA gelatin plus lubricin group being most stable.

CONCLUSIONS

The results suggest that tendon surface treatment using HA and lubricin can improve the gliding of human PL tendon in vitro. If validated in vivo, tendon surface treatment has the potential to improve the gliding ability of tendon grafts clinically.

Lubricin surface modification improves tendon gliding after tendon repair in a canine model in vitro

This study investigated the effects of lubricin on the gliding of repaired flexor digitorum profundus (FDP) tendons in vitro. Canine FDP tendons were completely lacerated, repaired with a modified Pennington technique, and treated with one of the following solutions: saline, carbodiimide derivatized gelatin/hyaluronic acid (cd-HA-gelatin), carbodiimide derivatized gelatin to which lubricin was added in a second step (cd-gelatin + lubricin), or carbodiimide derivatized gelatin/HA + lubricin (cd-HA-gelatin + lubricin). After treatment, gliding resistance was measured up to 1,000 cycles of simulated flexion/extension motion. The increase in average and peak gliding resistance in cd-HA-gelatin, cd-gelatin + lubricin, and cd-HA-gelatin + lubricin tendons was less than the control tendons after 1,000 cycles (p < 0.05). The increase in average gliding resistance of cd-HA-gelatin + lubricin treated tendons was also less than that of the cd-HA-gelatin treated tendons (p < 0.05). The surfaces of the repaired tendons and associated pulleys were assessed qualitatively with scanning electron microscopy and appeared smooth after 1,000 cycles of tendon motion for the cd-HA-gelatin, cd-gelatin + lubricin, and cd-HA-gelatin + lubricin treated tendons, while that of the saline control appeared roughened. These results suggest that tendon surface modification can improve tendon gliding ability, with a trend suggesting that lubricin fixed on the repaired tendon may provide additional improvement over that provided by HA and gelatin alone.

Substrate adhesion affects contraction and mechanical properties of fibroblast populated collagen lattices

Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure. The purpose of this study was to evaluate the effect of substrate adhesion on the contraction and mechanical properties of fibroblast populated collagen lattices. Bacteriological grade polystyrene (BGPS) plates and tissue culture polystyrene (TCPS) plates were used as substrates for incubation of fibroblast populated collagen lattices. Hydrophobicity of the polystyrene surfaces was measured by the static sessile contact angle method. Collagen lattice contraction was recorded for 2 weeks, after which the lattices were mechanically tested. The BGPS culture plate had a significantly larger contact angle and was more hydrophobic than the TCPS culture plate. Both hydrophobicity and peripheral detachment of the collagen gel significantly decreased the time lag before initiation of gel contraction and increased the strength of the fibroblast populated collagen lattices. Substrate adhesion affects the contractility and strength of cell seeded collagen gels. This information may be useful in developing tissue engineered tendons and ligaments.

MMP2 promoter polymorphism (C-1306T) and risk of recurrence in patients with hepatocellular carcinoma after transplantation

Genetic variants in matrix metalloproteinase (MMP) gene may influence the biological function of these enzymes and change their role in carcinogenesis and progression. The effect of MMP2 C-1306T and MMP9 C-1562T polymorphisms on genetic susceptibility has been investigated in various kinds of cancer. However, the relationship between these polymorphisms and risk of recurrence of hepatocellular carcinoma (HCC) after liver transplantation (LT) has not been reported. The present study was designed to investigate the association of these two loci with the risk of HCC recurrence in 93 HCC patients treated with LT. Genotyping was performed using direct DNA sequencing. For MMP2 C-1306T variant, patients with CT heterozygous conferred a 58% reduction in recurrence risk (risk ratio: 0.419; 95% confidence interval: 0.177-0.994). The mean recurrence-free survival for CT genotype was significantly longer than that for homozygous CC patients (30.4 vs 19.3 months, p = 0.019). However, no association was found between MMP9 C-1562T polymorphisms and recurrence of HCC (p = 0.259). These findings suggest that MMP2 promoter polymorphisms may provide some predictive value for HCC recurrence after LT.

Lubricin surface modification improves extrasynovial tendon gliding in a canine model in vitro

BACKGROUND

Lubricin is the principal lubricant in synovial fluid. Although lubricin has been identified in tendons, especially on the surface of intrasynovial tendons such as the flexor digitorum profundus tendon, its ability to improve tendon gliding is unknown. The purpose of this study was to investigate the effects of exogenously applied lubricin on the gliding of extrasynovial tendons in a canine model in vitro.

METHODS

Forty peroneus longus tendons, along with the proximal pulley in the ipsilateral hind paw, were harvested from adult mongrel dogs. After the gliding resistance of the normal tendons was measured, the tendons were treated with one of the following solutions: saline solution, lubricin, carbodiimide derivatized gelatin (cd-gelatin), carbodiimide derivatized gelatin with hyaluronic acid (cd-HA-gelatin), or carbodiimide derivatized gelatin to which lubricin had been added in a second step (cd-gelatin plus lubricin). Tendon gliding resistance was measured for 1000 cycles of simulated flexion-extension motion of the tendon. Transverse sections of the tendons were examined qualitatively at 100x magnification to estimate surface smoothness after 1000 cycles.

RESULTS

There was no significant difference in the gliding resistance between the tendons treated with saline solution and those treated with lubricin alone, or between the tendons treated with cd-HA-gelatin and those treated with cd-gelatin plus lubricin; however, the gliding resistance of the tendons treated with cd-gelatin plus lubricin was significantly lower than that of the tendons treated with saline solution, lubricin alone, or cd-gelatin alone (p < 0.05). After 1000 cycles of tendon motion, the gliding resistance of the tendons treated with cd-gelatin plus lubricin decreased 18.7% compared with the resistance before treatment, whereas the gliding resistance of the saline-solution-treated controls increased >400%. The tendon surfaces treated with cd-gelatin plus lubricin or with cd-HA-gelatin appeared smooth even after 1000 cycles of tendon motion, whereas the other surfaces appeared roughened.

CONCLUSIONS

While the addition of lubricin alone did not affect friction in this tendon gliding model, the results indicate that lubricin may preferentially adhere to a tendon surface pretreated with cd-gelatin and, when so fixed in place, lubricin does have an important effect on tendon lubrication.

The effect of carbodiimide-derivatized hyaluronic acid and gelatin surface modification on peroneus longus tendon graft in a short-term canine model in vivo

PURPOSE

We have recently reported that application of carbodiimide-derivatized hyaluronic acid and gelatin (cd-HA gelatin) to a peroneus longus tendon graft increased tendon graft gliding ability and decreased work of flexion compared with untreated grafts in a canine model in vivo. In this study, we investigated the effect of this modification on adhesions, stiffness, strength of the distal attachment, and fibroblast count.

METHODS

A total of 24 dogs were used for this study. The peroneus longus tendons of each hind leg were grafted into the 2nd and 5th digits of one forepaw in each dog. One peroneus longus tendon was treated with cd-HA gelatin prior to grafting, and the other one was immersed in 0.9% saline solution as a control. Animals were killed 1, 3, or 6 weeks postoperatively.

RESULTS

The adhesion score of cd-HA gelatin-treated tendons was significantly less than that in the saline-treated tendons at all time points. There was no significant difference in the indentation stiffness between HA- and saline-treated grafts at any time point. For the ultimate force at the distal attachment, there was a significant difference among the time points, with a steady increase over time, but no significant difference between treated and control tendons at any time point. There was no significant difference in fibroblast count between treated and control tendons at any time point.

CONCLUSIONS

Although gross adhesion formation was less, there was no significant difference in strength at the distal tendon-bone interface, cellularity, or tendon graft stiffness when comparing saline-treated and cd-HA gelatin-treated tendon grafts in vivo.

Enhancing the strength of the tendon-suture interface using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and cyanoacrylate

PURPOSE

Preventing gap or rupture is important to achieving a successful outcome after tendon repair. Weak sutures break; strong sutures fail by pull-out at the tendon-suture interface. In this study, we investigated the use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and cyanoacrylate to enhance the strength of the tendon-suture interface.

METHODS

Twenty-four canine flexor digitorum profundus tendons were used to test EDC and cyanoacrylate reinforcement methods, with 12 tendons in each group. A single-loop suture technique was used to test the tendon-suture interface strength.

RESULTS

The mean ultimate strengths of the EDC group and the cyanoacrylate group were significantly higher than those of their respective control groups. The stiffness of the group with cyanoacrylate-augmented loops was significantly higher than that of its respective control group. There was no significant difference in stiffness between the 2 reinforcement methods.

CONCLUSIONS

Our results suggest that tendon-suture interface reinforcement may improve the pull-out failure strength of a suture construct and thereby increase the effectiveness of stronger suture materials. Future studies might address the effects of different kinds and methods of reinforcement with various suture materials and constructs and in different tissues.

Effect of curing time and concentration for a chemical treatment that improves surface gliding for extrasynovial tendon grafts in vitro

The purpose of this study was to evaluate whether treatment time and concentration of these reagents have an effect on the resulting gliding resistance. Forty peroneus longus (PL) tendons were used, from 20 adult mongrel dogs, along with the A2 pulley obtained from the ipsilateral hind paw. After the baseline gliding resistance was measured, the PL tendons were treated with one of three concentrations of hyaluronic acid (HA) and 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) or N-hydroxysuccinimide (NHS) mixed with 10% gelatin for various times (5, 30, and 60 min). Tendon friction was measured over 1000 cycles of simulated flexion/extension motion. Gliding resistance of the untreated PL tendons had no significant difference among the groups. After surface treatment with low concentration of HA and EDC/NHS for 5-min cure, the gliding resistance was similar to that of the untreated PL tendon and significantly higher than its 30- and 60-min treatment. For the rest of high concentration of HA and EDC/NHS groups, the gliding resistance was lower than that of untreated PL tendon. However, there was no significant difference among the timing points. It is possible to optimize the effect of surface treatment on friction and durability by regulating cure time and concentration of reagents in a canine extrasynovial tendon in vitro.

Establishment and characterization of a spontaneously immortalized porcine mammary epithelial cell line

We have established a spontaneously immortalized porcine mammary epithelial cell line (SI-PMEC) from the mammary gland of a lactating sow and maintained it long-term in culture by continuous subculturing. SI-PMEC cells were maintained for more than 8 months (70 passages) in DMEM/F12 medium supplemented with 10% fetal calf serum, insulin, and hydrocortisone without obvious signs of senescence. When grown at low density on a plastic substratum, SI-PMEC cells formed islands, and when grown to confluency, the cells formed a monolayer and aggregated with the characteristic cobblestone morphology of epithelial cells. The subcultured SI-PMEC cells appeared to proliferate without changes in morphology or growth pattern, with an estimated population doubling time of 20-22 h. With increasing density, SI-PMEC cells organized into lumen-like structures with elongated cells at the margins. SI-PMEC cells from stocks frozen at Passage 30 were subcultured up to 20 times without changes in cell viability, proliferation rate, or morphology. Furthermore, SI-PMEC cells remained immunopositive to an antibody against cytokeratin AE3 and immunonegative to an antibody against a human fibroblast antigen. The SI-PMEC cells could form functional structures resembling ducts, lateral-buds, and alveoli in a Matrigel matrix-dependent manner in vitro. When grown on the Matrigel and stimulated by prolactin, the cells differentiated and formed mammary gland structures and strongly expressed transcripts encoding the milk proteins alpha-lactalbumin, beta-casein, and beta-lactoglobulin. Our results indicate that the SI-PMEC cell line can be subpassaged many times and still form functional differentiated secretory structures. To our knowledge, this is the first report of an immortalized mammary epithelial cell line from pig.

Surface treatment of flexor tendon autografts with carbodiimide-derivatized hyaluronic Acid. An in vivo canine model

BACKGROUND

Clinical and experimental studies have demonstrated that restrictive adhesions and poor digital motion are common complications after extrasynovial tendon grafting in an intrasynovial environment. The purpose of this study was to test the hypothesis that surface modification of an extrasynovial tendon with use of a carbodiimide-derivatized hyaluronic acid-gelatin polymer (cd-HA) improves gliding ability and digital function after tendon grafting in a canine model in vivo.

METHODS

The peroneus longus tendons from both hindpaws of twenty-four dogs were harvested and transplanted to replace the flexor digitorum profundus tendons in the second and fifth digits of one forepaw. Prior to grafting, one of the peroneus longus tendons was coated with cd-HA, which consists of 1% hyaluronic acid, 10% gelatin, 0.25% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), and 0.25% N-hydroxysuccinimide (NHS), while the other was immersed in saline solution only. Eight dogs were killed at one, three, and six weeks. Digital normalized work of flexion, tendon gliding resistance, and hyaluronic acid quantification (with the hyaluronic acid-binding-protein staining technique) were the outcome measures.

RESULTS

The normalized work of flexion of the tendons treated with cd-HA was significantly lower than that of the saline-solution-treated controls at each time-point (p < 0.05). The gliding resistance of the cd-HA group was significantly lower than that of the saline-solution group at three and six weeks (p < 0.05). The ratio between the intensity of staining of the cd-HA-treated tendons with that of the saline-solution-treated controls was significantly greater at time-0 than at three or six weeks (p < 0.05), but there was no significant difference between time-0 and one-week values.

CONCLUSIONS

Treating the surface of an extrasynovial tendon autograft with a carbodiimide-derivatized hyaluronic acid-gelatin polymer decreases digital work of flexion and tendon gliding resistance in this flexor tendon graft model in vivo.

CLINICAL RELEVANCE

cd-HA gelatin may provide surgeons with a new and useful method to improve the quality of tendon graft surgery.

Gene transfection and expression in a primary culture of mammary epithelial cells isolated from lactating sows

Porcine mammary epithelial cells (PMECs) were isolated from lactating sow mammary glands and cultured on a matrix gel. Primary culture cells expressed significant amounts of the specific marker cytokeratin as determined by immunohistochemistry, and exhibited mammary-specific functions, such as transcription of alpha-lactalbumin, beta-casein and beta-lactoglobulin genes. They also formed mammospheres when the medium was supplemented with lactogenic hormones. The PMECs were used to study gene transfer and expression in vitro. A gene encoding enhanced green fluorescent protein (EGFP) was used as a reporter and two constructs were investigated, pEGFP-N1 (a vector constructed with a CMV promoter followed by the EGFP gene) and pGB562/GFP (a mammary gland-specific expression vector with regulatory sequences from the goat beta-casein gene linked to EGFP). The efficiency of DNA transfer into the cultured PMECs was about 20-30%. GFP expression in the pGB562/GFP-transfected PMECs was markedly stimulated by prolactin supplements in the medium. The established PMECs maintained optimal gene expression from 1 to 20 passages and appeared to provide an efficient and convenient system for assessing the expression of transgenes containing mammary gland-specific promoters.

Optimization of surface modifications of extrasynovial tendon to improve its gliding ability in a canine model in vitro

Previous studies have shown that the carboxyl groups in hyaluronic acid (HA) could be activated by 1-ethy 1-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) to form intermediate O-acylisoureas, which can chemically bind to exposed amino groups on the tendon surface, leading to improved gliding ability. However, the optimal ratio and concentrations of the components in this chemical mixture were not investigated. The purpose of this study was to optimize the constituents of this tissue engineering approach to tendon surface modification, to reduce friction and improve durability. Peroneus longus (PL) tendons (n=40) were harvested from adult mongrel dogs along with the A2 pulley obtained from the ipsilateral hind paw. After the gliding resistance of the normal PL tendon was measured, the tendons were treated under varying concentrations of HA (0.5, 1, and 2%) and EDC/NHS (0.05, 0.25, and 1%) mixed with a 10% gelatin. Tendon friction was measured for 1000 cycles of simulated flexion/extension motion. Following testing, the residual HA on the tendon surface was evaluated by immunohistochemisty. The gliding resistance of the untreated PL tendons had a mean value of 0.087+/-0.021 N. After surface treatment, there was no significant difference in friction due to HA concentration alone, but the concentration of EDC/NHS and the interaction between HA concentration and EDC/NHS concentration had a significant effect on friction. Regardless of HA concentration, the friction after 1000 cycles was significantly decreased in preparations which included a 1% concentration of EDC/NHS. The tendons with lower gliding resistance presented a smoother surface on light microscopy and maintained more residual HA on the tendon surface. By varying the relative concentrations of HA, EDC, and NHS it is possible to optimize the effect of surface treatment on friction and durability in a canine extrasynovial tendon in vitro.