Sustained intra-cartilage delivery of low dose dexamethasone using a cationic carrier for treatment of post traumatic osteoarthritis.

Disease-modifying osteoarthritis drugs (DMOADs) should reach their intra-tissue target sites at optimal doses for clinical efficacy. The dense, negatively charged matrix of cartilage poses a major hindrance to the transport of potential therapeutics. In this work, electrostatic interactions were utilised to overcome this challenge and enable higher uptake, full-thickness penetration and enhanced retention of dexamethasone (Dex) inside rabbit cartilage. This was accomplished by using the positively charged glycoprotein avidin as nanocarrier, conjugated to Dex by releasable linkers. Therapeutic effects of a single intra-articular injection of low dose avidin-Dex (0.5 mg Dex) were evaluated in rabbits 3 weeks after anterior cruciate ligament transection (ACLT). Immunostaining confirmed that avidin penetrated the full cartilage thickness and was retained for at least 3 weeks. Avidin-Dex suppressed injury-induced joint swelling and catabolic gene expression to a greater extent than free Dex. It also significantly improved the histological score of cell infiltration and morphogenesis within the periarticular synovium. Micro-computed tomography confirmed the reduced incidence and volume of osteophytes following avidin-Dex treatment. However, neither treatment restored the loss of cartilage stiffness following ACLT, suggesting the need for a combinational therapy with a pro-anabolic factor for enhancing matrix biosynthesis. The avidin dose used caused significant glycosaminoglycan (GAG) loss, suggesting the use of higher Dex : avidin ratios in future formulations, such that the delivered avidin dose could be much less than that shown to affect GAGs. This charge-based delivery system converted cartilage into a drug depot that could also be employed for delivery to nearby synovium, menisci and ligaments, enabling clinical translation of a variety of DMOADs.

Revascularisation pattern of ruptured flexor tendon grafts in anterior cruciate ligament reconstruction: A histological study. / Patrón de revascularización de injertos de tendones flexores rotos en reconstrucción de ligamento cruzado anterior: un estudio histológico.

INTRODUCTION: For successful anterior cruciate ligament (ACL) reconstruction, revascularisation and histological maturation are necessary, as their failure can cause graft rupture. PURPOSE: The purpose of this study was to describe differences in the histological maturation of early failed plasty (less than 12 months after surgery) and late failed plasty (more than 12 months after surgery) in patients with re-rupture after ACL reconstruction with hamstring tendons. MATERIAL AND METHODS: A descriptive observational study was conducted on a consecutive series of 20 patients whose ACL reconstruction had failed. Graft biopsy samples were obtained during the revision surgery from the proximal, medial, and distal graft remnants. The samples were evaluated by light microscopy, and the vascularity and maturation of the samples were established by histological scoring. RESULTS: The most common aetiology of reconstruction failure (86.6%) was a specific event with non-contact mechanism. The patients with re-rupture of their ACL plasty less than 12 months after surgery had substance vessels that were less deep. The distal segment of the graft in those patients showed a delay in histological maturation with fewer collagen fibres. CONCLUSION: In patients whose ACL grafts failed less than 12 months after surgery, a lower distribution of blood vessels and collagen fibres was found that were less ordered in the distal graft. These results indicate a delay in maturation, which leads to a higher risk of graft failure.

[Treatment of acute full-thickness chondral defects with high molecular weight hyaluronic acid; an experimental model]. / Tratamiento de lesiones condrales agudas de espesor completo con ácido hialurónico de alto peso molecular; un modelo experimental.

PURPOSE: To evaluate the effect of 2 different protocols of intra-articular hyaluronic acid (HA, hylan G-F20) to articular cartilage regeneration in acute full-thickness chondral defects. MATERIALS AND METHODS: Full-thickness chondral defects of 3 x 6 mm were performed into the lateral femoral condyles of New Zealand rabbits, treated with a single or three doses of HA. The animals were sacrified at 12 weeks and the regenerated tissue was evaluated by direct observation and histology with the ICRS scale. Macroscopically, in both groups treated with HA the defects were filled with irregular tissue with areas similar to hyaline cartilage and others in which depressed areas with exposed subchondral bone were observed. Histological analysis showed in both groups treated with HA a hyaline-like cartilage compared to control group. However, the score of the International Cartilage Repair Society (ICRS) scale did not show differences between the groups treated with HA. CONCLUSION: The use of single dose or 3 doses of AH in acute chondral lesions has a limited and similar benefit in articular cartilage regeneration.

Ablation dynamics in laser sclerostomy Ab externo by means of pulsed lasers in the mid-infrared spectral range.

BACKGROUND AND OBJECTIVE: Sclerostomy ab externo with pulsed laser systems is currently in phase II clinical trials. The authors investigated the ablation dynamics of tissue treated with pulsed laser systems in the mid-infrared range to estimate the extent of thermo-mechanical damage to the sclera and the anterior chamber. MATERIALS AND METHODS: Freshly harvested porcine eyes were used. A bare 400-micron fiber in direct contact with tissue was used for fistulization. Polarization light microscopy, fast-flash photography, as well as optical and acoustic transients were performed for analysis. RESULTS: Substantial mechanical tissue deformation and dissections were found during pulsed laser ablation. The mechanical damage range within tissue far exceeds the pure thermal damage zone. Aspheric cavitation bubbles of up to 3 mm in length penetrate the anterior chamber after perforation. The cavitation demonstrates a significantly larger time constant in tissue than in water. CONCLUSIONS: Early fistula occlusions due to iris adherences may be attributed to iris trauma caused by cavitation. In response to the findings of this study, the authors propose an automatic feedback system to control the ablation process and minimize secondary ocular tissue effects. With respect to the overall damage zones, a new continuous-wave, mid-infrared diode laser system seems to be superior to pulsed laser systems.

Renal hemodynamics in essential hypertensives treated with losartan.

ACE-inhibitors are known to have special renal effects, i.e. they increase ERPF, decrease the filtration fraction and lower proteinuria. These effects can be due to a decrease in angiotensin II (AII) levels as well as an increase in bradykinin. New and more specific AII-receptor antagonists may help to distinguish between effects exerted by angiotensin II and those exerted by bradykinin. We investigated the effects of losartan in 9 patients with essential hypertension (sitting mean diastolic blood pressure 95-120 mmHg). Renal hemodynamics were measured by continuous inulin-and PAH-clearance (GFR and RPF) after stopping antihypertensive therapy for 1 week, followed by a 2-week placebo period and after a 4-week treatment phase with losartan (50 mg/die) followed by a therapy with an ACE-inhibitor (ramipril 5mg/die). Additionally, urine albumin excretion (UAE) was measured. Treatment of patients with essential hypertension with losartan resulted in a significant decrease of MAP after three weeks of treatment (121 +/- 8 mmHg under placebo and 114 +/- 10 mmHg under losartan; * = p < 0.05). MAP after four weeks of losartan treatment was 115 +/- 11 mmHg. Regarding changes in renal hemodynamics we could not demonstrate a significant change for neither losartan nor the ACE-inhibitor. Urine albumin excretion was reduced by both treatment regimens in correlation to the magnitude of blood pressure reduction. Our data indicate that losartan induced a significant reduction in MAP in patients with essential arterial hypertension with only moderate effects on renal hemodynamics.

Laser sclerostomy ab interno using continuous wave and pulsed lasers in a rabbit model.

PURPOSE: This experimental study was designed to find an optimal combination of parameters for a gonioscopic ab interno approach to laser sclerostomy. METHODS: Laser sclerostomy ab interno was performed delivering the laser energy via a slit lamp and a gonioscopic contact lens to the iridocorneal angle. The laser energy is required to be well transmitted by the cornea and at the same time to be maximally absorbed by the sclera at the iridocorneal angle. For local enhancement of absorption the sclera was stained with the biocompatible dyes Fluorescein (absorption maximum at 480 nm) and Methylene blue (absorption maximum at 668 nm) applied by iontophoresis. A continuous-wave (cw)-Argon laser and a cw-dye laser produced relatively long pulses (200 ms) at wavelengths matching with these respective maxima. Additionally a pulsed dye laser emitting shorter pulses (2 microseconds) was successively adapted to the wavelengths of the two maxima. In some cases a Q-switched Nd: YAG laser had to be used for perforation of Descemet's membrane. A total of 44 rabbit eyes was treated to compare the results for these four different laser/dye combinations. RESULTS: While no successfull perforation of the sclera could be achieved using the cw-dye laser with scleral staining by Methylene blue, the intraoperative success rate ranged between 59% and 75% for the other three laser/dye combinations. Histological examinations of the eyes on the first postoperative day showed smaller thermal necrosis zones, but more often fibrin reactions when using the shorter pulse length. Although we often found iris adherences to the internal fistula ostium, no major complications were observed. CONCLUSION: Further improvement of intraoperative success rates is needed, before clinical application of the approach can be considered.

[The laser-assisted balloon angioplasty of insufficient hemodialysis-access fistulae]. / Lasergestützte Ballonangioplastie insuffizienter Hämodialysefisteln.

Patients with end-stage renal failure frequently develop venous stenoses or occlusions in their haemodialysis access fistulas caused by intimal fibrosis. A complete dilation with high pressure balloons up to 20 atm may be unsuccessful in such cases. We investigated two pulsed dye laser devices for the ablation of obstructions, which were not adequately treatable with a previous balloon angioplasty. From 11/90 to 4/92 a total amount of 154 PTAs of haemodialysis access fistulas were performed. In 23 of them additive laser angioplasty was necessary. 20 patients with Cimino fistulas presented 28 stenoses and two occlusions, whereas all the three patients with Goretex loops presented with occlusions. Two pulsed dye laser devices emitted at the wavelengths 504 nm (green) and 595 nm (red). Technical success was achieved in 22/23 cases, but clinical success was obtained in only 20/23 patients, due to two early reocclusions caused by thrombosis. 5 restenoses occurred two, three, 10, and twice 14 months after angioplasty with a mean follow-up period of 13.5 (5-18) months. Pulsed dye laser ablation in haemodialysis access fistula lesions due to intimal fibrosis greatly enriches radiological recanalisation techniques and is a valuable alternative to surgery if stand-alone balloon PTA fails.

[Experimental laser sclerostomy ab externo with erbium:YAG laser]. / Experimentelle Lasersklerostomie ab externo mit dem Erbium:YAG-Laser.

A fistula from the anterior chamber of the eye into the subconjunctival space can be created by external laser application (laser sclerostomy). A pulsed (200 microseconds) Erbium-YAG laser was used because of the high scleral absorption. The laser energy was applied via a special fiber, which was inserted into a special application cannula to guide it into the subconjunctival space. A total of 24 rabbit eyes were treated and examined histologically after various postoperative periods. In all cases a functioning fistula and a marked reduction of the IOP (mean value 13 mmHg to 2 mmHg) were detected. On average, 60 mJ was required. The zone of thermal damage was limited to 40 microns. Cornea and lens showed no evidence of damage after 1 day or after 4 weeks. In the rabbit model, the fistulas were closed within 2 weeks, and long-term persistence of the fistula must therefore be verified in a clinical study. The method presented is minimally invasive, requires only a short operation time, causes minimal trauma to the conjunctiva, and may become an alternative to traditional fistulization operations.

Laser sclerostomy ab externo using mid infrared lasers.

An ab externo fistulizing procedure (sclerostomy) was performed in vivo in 48 rabbit eyes using a pulsed (20 microseconds and 200 microseconds) Holmium:YAG (Ho:YAG) laser (2120 nm) and a pulsed (200 microseconds) Erbium:YAG (Er:YAG) laser (2940 nm). The laser energy was delivered via an infrared transmitting fiber in contact with the sclera, with the fiber inserted into a specially sharpened retractable cannula in order to guide it into the subconjunctival space. An additional optical fiber-fiber coupling system was required for the Er-YAG laser. A patent fistula (200-micrometers diameter) with formation of a filtering bleb and marked intraocular pressure reduction was achieved in nearly all cases. Significant intraoperative or postoperative complications occurred only with the 20-microsecond Ho:YAG laser. Trauma to the conjunctiva was as minimal as in a subconjunctival injection. The Er:YAG laser created a smaller thermal damage zone at the fistula walls and required significantly less laser energy than the Ho-YAG laser.

Initial clinical experience with a new pulsed dye laser device in angioplasty of limb ischemia and shunt fistula obstructions.

Selective plaque ablation with laser radiation at 405-530 nm in vitro has been reported. We investigated the possibilities of a new pulsed dye laser device for in vivo recanalization of arteries in ischemic lower limbs and stenoses/occlusions of arterio-venous hemodialysis shunt fistulae. A specially designed 9F or 7F multifiber catheter was used for treatment of 10 patients with lower limb artery obliterations and 11 patients with malfunctioning hemodialysis access fistulae (HAF). The recanalization technical success was 5/5 in the iliac arteries (IA), 4/5 in the superficial femoral arteries (SFA), and 11/11 in the HAF. Early re-occlusions occurred in one SFA and one IA, respectively, caused by very bad run-off. There was one clinically insignificant SFA perforation. Additional balloon angioplasty was considered necessary in 10/16 lesions. Mean ankle-arm index increased from 0.68 to 0.97. With two exceptions all HAF patients were re-integrated in the dialysis program. Pulsed dye laser angioplasty promises to be an effective and fast method for plaque ablation/debulking. The first clinical experience confirms previous in vitro results. In particular laser recanalization may become the method of choice for treatment of rigid HAF obstructions and it seems to be superior to vascular surgery or balloon angioplasty alone.

A new concept for a realtime feedback system in angioplasty with a flashlamp pumped dye laser.

The feasibility of using a pulsed dye laser in angioplasty for detection and disintegration of calcified plaques was studied in vitro. A flashlamp-pumped dye laser (495 nm, 2 microseconds) was used as the exciting source for laser-induced-fluorescence (LIF) signals. Spectral data in the 520 nm to 800 nm region of normal intima, calcified plaque and fibro-fatty plaques were analyzed with an optical multichannel analyzer, using the same fiber for energy delivery and fluorescence diagnostic. Good signal to noise ratio and different spectra for different specimens were obtained within only 2 microseconds. The spectral difference is caused by selective reabsorption of oxyhemoglobin in the vessel wall. Time resolved LIF-spectroscopy shows that the fluorescence intensity reaches its maximum value before the maximum laser intensity is delivered. Fluorescence analysis can be performed in less than 300 ns and therefore the laser can be controlled before plasma threshold is reached. The described in vitro results can lead to a clinical useful feedbacksystem for energy control of microseconds lasers in angioplasty if the blood interference effects can be minimized by changing the laser excitation wavelength or staining the tissue.

Kinetics of delayed-type hypersensitivity (DTH) reactions and Ig levels in FCA-induced dysgammaglobulinemic B 12 chickens.

Kinetic studies on delayed-type hypersensitivity (DTH) to Freund's complete adjuvant (FCA) have been done in spontaneous dysgammaglobulinemic chickens, which have drastically reduced serum IgG levels and highly elevated IgM and IgA levels - in comparison to chickens with normal immunoglobulin (Ig) levels. For a period of five weeks, serum Ig levels, leukocyte migration inhibition (LMIT), and wattle reaction were examined once a week. In normal chickens, FCA treatment resulted in stimulation of IgG, but did not affect IgM synthesis, whereas in spontaneous dysgammaglobulinemic chickens, FCA stimulated only IgM synthesis. Spontaneous dysgammaglobulinemic chickens could produce LMIT and wattle reactions as well as normal birds. Whereas in normal birds, both types of DTH reactions declined continuously about the third or fourth week, in immunodeficient chickens, further increments of LMIT and wattle reactions up to the fifth week persisted as evidenced by LMIT and wattle reactions even 15 weeks after sensitization. In contrast, only minimal signs of reactivity were seen in normal birds. Spontaneous dysgammaglobulinemic chickens, nearly unable to synthesize IgG even after FCA stimulation in vivo, lack suppressive mechanisms regulating the course of DTH reaction to FCA. The possible B-cell nature of the regulatory cell population is discussed.