Untreated Rabbits Research Articles

Comparison of Riboflavin/Ultraviolet-A Cross-Linking in Porcine, Rabbit, and Human Sclera

Purpose. To compare the biomechanical properties of porcine, rabbit, and human sclera before and after riboflavin/ultraviolet-A (UVA) collagen cross-linking (CXL). Methods. Eight rabbits, 8 porcine eyeballs, and 8 human eyeballs were included. One rabbit eye and half of each bisected human and porcine eyeball were treated with riboflavin/UVA CXL. Untreated fellow rabbit eyes and eyeball halves served as controls. A 10 mm × 20 mm scleral band was harvested from each specimen. From this band, two 3.5 mm × 15.0 mm strips were prepared for biomechanical testing. The biomechanical parameters were ultimate stress, stress and Young's modulus. Results. Values of stress, and Young's modulus showed that human sclera was 4 times stiffer than porcine sclera and 3 times stiffer than rabbit sclera. In rabbit sclera, both the stress and Young's modulus were significantly increased by CXL (P < 0.05). In porcine sclera, only the ultimate stress was significantly increased by CXL (P < 0.05). The biomechanical properties of human sclera were not statistically affected by CXL (P > 0.05). Conclusions. Human sclera has higher biomechanical stiffness than porcine and rabbit sclera. With the same irradiation dose, riboflavin/UVA CXL increases the biomechanical stiffness of rabbit sclera but not porcine or human sclera.

Biochemical response of rabbits following experimental &lt;i&gt;trypanosoma brucei brucei&lt;/i&gt; infection, treatment and re-infection

The biochemical response of rabbits experimentally infected with Trypanosoma brucei brucei was studied following infection, treatment and re-infection. Twenty five cross bred New zealand and Chinchila White rabbits were divided into 5 groups (A, B, C, D &amp; E) of 5 rabbits each. All the rabbits were infected with Trypanosoma brucei brucei (5x106 organism/ml). All the infected rabbits developed parasitemia between days 4 and 5 pi. The control group (group A) was allowed to run a chronic trypanosoma infection while groups B and D were treated with diminazene aceturate and C and E with isometamidium chloride, 7 days post infection (pi). Groups B and C were re-infected 14 days post treatment (pt) while groups D and E were re-infected 28 days pt. Elevation of serum ALP (Alkaline phosphatase), total protein and urea and decrease in albumin concentration was observed. Serum creatinine concentration declined slightly. Chemotherapy was confirmed effective by the clearance of the parasite in the blood of the treated animals either with diminazene aceturate or isometamidium chloride. Parasitemia was detected six days post re-infection (pri) when the treated animals were re-infected either at 2 weeks or 4 weeks pt. All the untreated rabbits died between days 28 and 49 of the infection while those re-infected after treatment and cure died between days 42 and 56 (post re-infection) pri. Though the two trypanocides used in this work were therapeutically effective, treatment need to be repeated not later than four weeks after the last treatment for effective control of trypanosomosis.Keywords: Biochemical responses, Diminazene aceturate, Isometamidium chloride, Rabbits, Trypanosomosis.

Bilateral acute pyogenic conjunctivitis with iritis induced by unilateral topical application of bacterial peptidoglycan muramyl dipeptide in adult rabbits

The factors responsible for the conjunctivitis and iritis associated with acute ocular infection and post enteric inflammatory disease are not fully known. The pro-inflammatory activity of unilateral topical application of muramyl dipeptide (MDP; the smallest bio-active Gram-positive and Gram-negative bacterial cell wall component) was investigated in adult rabbits. The resultant bilateral conjunctivitis/iritis and pyogenic responses were characterized. Bilateral symptoms were graded by slit lamp examinations; tear fluid, Schirmer tests (tear production), blood and aqueous humor (AH) samples were obtained from MDP-treated and untreated rabbits. MDP concentration, gamma-glutamyltranspeptidase activity (GGT; key enzyme in glutathione recapture, xenobiotic detoxification, eicosanoid synthesis and neutrophil function), protein concentration, and tear cell density, cytology, and immunofluorescent antibody reactivity to GGT and calreticulin (CRT; MDP-binding protein) were determined. MDP was cleared from ipsilateral tears and serum by 6 h, but was undetected in mock-treated contralateral tears. Bilateral signs of acute transient pyogenic conjunctivitis, characterized by tearing, lid edema, conjunctival hyperemia, chemosis and leukocytic infiltrate with iritis (erythema and aqueous flare) were detected. Milder symptoms occurred in the mock-treated contralateral eyes. Bilateral symptoms, tear production, tear protein, GGT activity, and mucopurulent discharge (containing up to 2.5–5.0 × 106 cells/mL) were elevated 4–8 h post MDP and resolved to near pre-treatment levels by 24 h. Tear GGT activity and protein levels were higher in MDP-treated and mock-treated contralateral eyes than in eyes of untreated adult rabbits (p's < 0.001). Elevated tear GGT activity was associated with histopathology and increased vascular and epithelial permeability to serum protein, GGT-positive epithelia cells, macrophages and heterophils. Repeat MDP applications induced recurrent induction and resolution patterns of bilateral conjunctivitis/iritis and tear GGT activity, but ipsilateral GGT responses were lower. The results suggest unilateral topical MDP application to adult rabbit eyes induces a bilateral acute pyogenic conjunctivitis/iritis (PCI) characterized by increased vascular and epithelial permeability similar to acute bacterial conjunctivitis in man. The detection of CRT/GGT positive heterophils in tears suggests efferocytosis (phagocytosis of dead/dying cells). Tear GGT activity may be a useful means to quantify MDP-induced toxicity and extraocular inflammation.

Role of the JNK pathway on the expression of inflammatory factors in alveolar macrophages under mechanical ventilation

The aim of this study was to investigate the regulatory role of the c-JUN N-terminal kinase (JNK) pathway on interleukin (IL)-8 and tumor necrosis factor (TNF)-α expression in alveolar macrophages (AMs) of injured lung. Lung injury was induced in the New Zealand white rabbit by applying continuous mechanical ventilation with or without inhibitor of JNK (SP600125), p38 (SB203580), or ERK (PD98059). Non-ventilated rabbits (controls) were compared with the different ventilation-days groups, and untreated rabbits ventilated for 3 days (controls) were compared with the different inhibitor groups. We found that mechanical ventilation caused significant decreases in partial pressures of carbon dioxide (pCO2) and oxygen (pO2) of untreated rabbits (all times, P<0.05), but the inhibitor-treated groups showed no change in either blood-gas indicator (all times, P>0.05). Mechanical ventilation caused time-dependent increases in mRNA and protein levels of TNF-α and IL-8 in AMs and in serum of untreated rabbits, with the peak levels occurring at day 3 of ventilation. The SP600125-treated group showed significantly decreased TNF-α expression, but no significant change in IL-8 expression. Neither the SB203580- nor PD98059-treated groups showed any significant change in TNF-α or IL-8 expression. MAPKs' inhibitors could reduce mechanical ventilation-induced inflammation, and SP600125 produced the most robust decrease in inflammation. Mechanical ventilation-induced lung injury stimulates IL-8 and TNF-α expression in rabbit AMs in a time-dependent manner. The JNK pathway plays an important role in mechanical ventilation-stimulated TNF-α expression in AMs, but the injury-stimulated IL-8 expression may be regulated by other signaling pathways.

Inflammatory Effect of Monopolar Radiofrequency Treatment on Collagen Fibrils in Rabbit Skins

This study quantitatively examined the effects of monopolar radiofrequency (RF) treatment on the progressive nanostructural changes in the inflammatory effect of in vivo rabbit dermal collagen fibrils during postoperative 7 days. Conventional histologic analysis and atomic force microscopy (AFM) were employed to assess the nanostructural dermal response in 6 RF groups that underwent 2 passes of RF treatments (10 and 20 W), and 1 untreated control rabbit. After monopolar RF treatment, the rabbit skin clearly showed changes in the collagen network structure. The RF-treated group showed regular parallel arrangement of collagen fibrils whereas normal group showed tangled nanostructures. This phenomenon was remarkable at postoperative 7 days. Therefore, monopolar RF treatment leads to underlying collagen contracture and promotes new collagen formation. A multi-pass treatment of low-energy RF led to the highest contraction of collagen fibrils at the nanostructural level, compared to a single pass of high-energy RF.

Effects of Linezolid on Suppressing In Vivo Production of Staphylococcal Toxins and Improving Survival Outcomes in a Rabbit Model of Methicillin-Resistant Staphylococcus aureus Necrotizing Pneumonia

Linezolid is recommended for treatment of pneumonia and other invasive infections caused by methicillin-resistant Staphylococcus aureus (MRSA). The premise underlying this recommendation is that linezolid inhibits in vivo production of potent staphylococcal exotoxins, including Panton-Valentine leukocidin (PVL) and α-hemolysin (Hla), although supporting evidence is lacking. A rabbit model of necrotizing pneumonia using MRSA clone USA300 was used to compare therapeutic effects of linezolid (50 mg/kg 3 times/day) and vancomycin (30 mg/kg 2 times/day) administered 1.5, 4, and 9 hours after infection on host survival outcomes and in vivo bacterial toxin production. Mortality rates were 100% for untreated rabbits and 83%-100% for vancomycin-treated rabbits. In contrast, mortality rates were 25%, 50%, and 100% for rabbits treated with linezolid 1.5, 4, and 9 hours after infection, respectively. Compared with untreated and vancomycin-treated rabbits, improved survival of rabbits treated 1.5 hours after infection with linezolid was associated with a significant decrease in bacterial counts, suppressed bacterial production of PVL and Hla, and reduced production of the neutrophil-chemoattractant interleukin 8 in the lungs. Across the study interval, only early treatment with linezolid resulted in significant suppression of exotoxin synthesis and improved survival outcomes in a rabbit model of MRSA necrotizing pneumonia.

Bacillus anthracis Protective Antigen Kinetics in Inhalation Spore-Challenged Untreated or Levofloxacin/ Raxibacumab-Treated New Zealand White Rabbits

Inhaled Bacillus anthracis spores germinate and the subsequent vegetative growth results in bacteremia and toxin production. Anthrax toxin is tripartite: the lethal factor and edema factor are enzymatic moieties, while the protective antigen (PA) binds to cell receptors and the enzymatic moieties. Antibiotics can control B. anthracis bacteremia, whereas raxibacumab binds PA and blocks lethal toxin effects. This study assessed plasma PA kinetics in rabbits following an inhaled B. anthracis spore challenge. Additionally, at 84 h post-challenge, 42% of challenged rabbits that had survived were treated with either levofloxacin/placebo or levofloxacin/raxibacumab. The profiles were modeled using a modified Gompertz/second exponential growth phase model in untreated rabbits, with added monoexponential PA elimination in treated rabbits. Shorter survival times were related to a higher plateau and a faster increase in PA levels. PA elimination half-lives were 10 and 19 h for the levofloxacin/placebo and levofloxacin/raxibacumab groups, respectively, with the difference attributable to persistent circulating PA-raxibacumab complex. PA kinetics were similar between untreated and treated rabbits, with one exception: treated rabbits had a plateau phase nearly twice as long as that for untreated rabbits. Treated rabbits that succumbed to disease had higher plateau PA levels and shorter plateau duration than surviving treated rabbits.

Red Cell-Derived Microparticles (RMP) As Hemostatic Agent: Evaluation in a Rabbit Ear Bleeding Model.

Abstract 2238 Introduction:We are developing RMP for use as an infusible hemostatic agent to treat bleeding conditions. Preliminary evaluations in vitro, such as by thromboelesatography (TEG), were very promising, and were supported by in vivo studies in a small animal (rat) [Haemophilia 2011; 17: 44]. It was shown that RMP not only accelerate coagulation and correct hemostatic aberration of factor-deficient plasma but also enhance platelet aggregation and adhesion, suggesting its efficacy in both primary and secondary hemostasis [Blood 2011; 118:3263]. Here we report results of initial studies in a large animal, the rabbit ear bleeding model. Methods:RMP were produced by high-pressure extrusion of human RBC, converting >99% of RBC to RMP. Hemostatic efficacy was evaluated in a rabbit ear bleeding model. New Zealand male white rabbits of 2.5–3.5 kg were used. After sedation, the ear was prepared by chlorhexidime scrub, then a standard incision 6 mm wide was made to penetrate the ear (#11 scalpel blade), in a region of the ear devoid of macroscopic (visible) vessels. The ear was maintained at 37°C with a heating pad. Bleeding time (BT) was defined as the time required for the disappearance of blood stains on a filter paper blot. To reliably measure reduction of BT by the RMP product, bleeding was prolonged by administration of busulfan (20 mg/kg SC) twice each at days 1 and 3, to suppress bone marrow, resulting in thrombocytopenia after 7–12 days. BT was significantly prolonged in animals when platelet counts fell to <60,000/μL. This regimen allowed all animals to survive, but higher doses of busulfan was toxic and caused severe pancytopenia, unacceptable for experimentation. Results:In normal (untreated) rabbits, the BT was 90 ±20 seconds (n = 12). Injection of RMP (3×109/kg, IV) in untreated rabbits resulted in no significant changes in BT, and no major adverse events were seen (n = 6). In thrombocytopenic rabbits, the BT was prolonged to 620 ±130 sec., and prolongation of BT correlated with decrease in platelet counts, 30,000 – 60,000/μL (n = 12). In this range of platelet counts, injection of RMP (at either 1 × 109 or 3 × 109/kg, IV) induced significant shortening of BT, to 440 ±90 sec (n = 8) at the lower dose (p<0.01), and to 280 ±65 sec (n = 8), at the higher dose (p < 0.001). When platelet counts dropped below 10,000/μL and BT >15 min, RMP had no significant effect. The hemostatic effects disappeared if >30 min elapsed between RMP infusion and making the incision, indicating a short half-life of RMP in circulation. Conclusions:These data confirm efficacy of RMP in thrombocytopenic rabbits. Hemostatic efficacy of RMP was evident in moderate thrombocytopenia, and was dose-dependent. However, efficacy fell off if platelets <10,000/μL, indicating that RMP augment platelet activity but do not replace platelets. In both thrombocytopenic and non-thrombocytopenic rabbits, no major adverse reactions were observed with infusion of RMP. Disclosures:No relevant conflicts of interest to declare.

Telavancin in Therapy of Experimental Aortic Valve Endocarditis in Rabbits Due to Daptomycin-Nonsusceptible Methicillin-Resistant Staphylococcus aureus

A number of cases of both methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains that have developed daptomycin resistance (DAP-R) have been reported. Telavancin (TLV) is a lipoglycopeptide agent with a dual mechanism of activity (cell wall synthesis inhibition plus depolarization of the bacterial cell membrane). Five recent daptomycin-susceptible (DAP-S)/DAP-R MRSA isogenic strain pairs were evaluated for in vitro TLV susceptibility. All five DAP-R strains (DAP MICs ranging from 2 to 4 μg/ml) were susceptible to TLV (MICs of ≤0.38 μg/ml). In vitro time-kill analyses also revealed that several TLV concentrations (1-, 2-, and 4-fold MICs) caused rapid killing against the DAP-R strains. Moreover, for 3 of 5 DAP-R strains (REF2145, A215, and B(2.0)), supra-MICs of TLV were effective at preventing regrowth at 24 h of incubation. Further, the combination of TLV plus oxacillin (at 0.25× or 0.50× MIC for each agent) increased killing of DAP-R MRSA strains REF2145 and A215 at 24 h (∼2-log and 5-log reductions versus TLV and oxacillin alone, respectively). Finally, using a rabbit model of aortic valve endocarditis caused by DAP-R strain REF2145, TLV therapy produced a mean reduction of >4.5 log(10) CFU/g in vegetations, kidneys, and spleen compared to untreated or DAP-treated rabbits. Moreover, TLV-treated rabbits had a significantly higher percentage of sterile tissue cultures (87% in vegetations and 100% in kidney and spleen) than all other treatment groups (P < 0.0001). Together, these results demonstrate that TLV has potent bactericidal activity in vitro and in vivo against DAP-R MRSA isolates.

Corneal Biomechanical Properties from Two-Dimensional Corneal Flap Extensiometry: Application to UV-Riboflavin Cross-Linking

Corneal biomechanical properties are usually measured by strip extensiometry or inflation methods. We developed a two-dimensional (2D) flap extensiometry technique, combining the advantages of both methods, and applied it to measure the effect of UV-Riboflavin cross-linking (CXL). Corneal flaps (13 pig/8 rabbit) from the de-epithelialized anterior stroma (96 μm) were mounted on a custom chamber, consisting of a BK7 lens, a reflective retina, and two reservoirs (filled with Riboflavin and silicone oil). Stretching the corneal flap during five pressure increase/decrease cycles (0-30 mm Hg) changed the refractive power of the system, whose Zernike aberrations were monitored with a ray-tracing aberrometer. Porcine flaps were used to test the system. Rabbits were treated with CXL unilaterally in vivo following standard clinical procedures. Flaps were measured 1 month postoperatively. An analytical model allowed estimating Young's modulus from the change in surface (strain) and pressure (stress). Confocal microscopy examination was performed before, and at different times after CXL. Flap curvature changed with increased function of IOP in pig flaps (23.4 × 10⁻³ D/mm Hg). In rabbit flaps curvature changed significantly less in 1 month post CXL (P = 0.026) than in untreated corneas [17.0 vs. 6.36 millidiopter (mD)/mm Hg]. Young's modulus was 2.29 megapascals (MPa) in porcine corneas, 1.98 MPa in untreated rabbit corneas, and 4.83 MPa in 1 month post CXL rabbit corneas. At the same time, highly reflective structures were observed in the rabbit midstroma after treatment. 2D flap extensiometry allows estimating corneal elasticity in vitro. The measurements are spatially resolved in depth, minimize the effects of corneal hydration, and preserve the integrity of the cornea. The method proved the efficacy of CXL in increasing corneal rigidity after 1 month in rabbits.

Activity of MMP‐9 after repair of abdominal wall defects with acellular and crosslinked bovine pericardium in rabbit

This study was undertaken for the identification of matrix metalloproteinases (MMPs) in extracts obtained from native, acellular and crosslinked bovine pericardium (in vitro), as well as in the plasma after implantation of these biomaterials in rabbits (in vivo). Native pericardium (NP) expressed a 72 kDa (MMP-2) band; whereas, in acellular pericardium (AP) two bands (10 kDa and 92 kDa) of MMPs were observed of which, 92 kDa band was very faint. AP crosslinked with glutaraldehyde did not show any gelatinase activity and thus reflects the creation of new additional chemical bonds between the collagen molecules which has been effectively removed. Gelatin zymography showed only one major band of 92 kDa in all the implanted and untreated rabbit plasma, but the relative amount of 92 kDa was 1-2 times higher in acellular bovine pericardium implanted rabbits as compared to crosslinked and native groups. In NP group, the 92 kDa band was the dullest among the three groups. This indicated that the level of MMP-9 corresponds to the degree of collagen degradation.

Gelam Honey Has a Protective Effect against Lipopolysaccharide (LPS)-Induced Organ Failure

Gelam honey exerts anti-inflammatory and antioxidant activities and is thought to have potent effects in reducing infections and healing wounds. The aim of this study was to investigate the effects of intravenously-injected Gelam honey in protecting organs from lethal doses of lipopolysaccharide (LPS). Six groups of rabbits (N = 6) were used in this study. Two groups acted as controls and received only saline and no LPS injections. For the test groups, 1 mL honey (500 mg/kg in saline) was intravenously injected into two groups (treated), while saline (1 mL) was injected into the other two groups (untreated); after 1 h, all four test groups were intravenously-injected with LPS (0.5 mg/kg). Eight hours after the LPS injection, blood and organs were collected from three groups (one from each treatment stream) and blood parameters were measured and biochemical tests, histopathology, and myeloperoxidase assessment were performed. For survival rate tests, rabbits from the remaining three groups were monitored over a 2-week period. Treatment with honey showed protective effects on organs through the improvement of organ blood parameters, reduced infiltration of neutrophils, and decreased myeloperoxidase activity. Honey-treated rabbits also showed reduced mortality after LPS injection compared with untreated rabbits. Honey may have a therapeutic effect in protecting organs during inflammatory diseases.

Efficacy of Gemifloxacin for the Treatment of Experimental Staphylococcus aureus Keratitis

The objective of the present study was to evaluate the effectiveness of topically applied gemifloxacin for the treatment of experimental Staphylococcus aureus keratitis in a rabbit model. Rabbit corneas were intrastromally injected with ~100 colony-forming units (CFU) of S. aureus ATCC25923. Eight hours (early treatment) or 16 h (late treatment) after the injection, 1 topical drop of balanced salt solution (BSS), gemifloxacin ophthalmic solution (0.5%), levofloxacin ophthalmic solution (0.5%), or gatifloxacin eye gel (0.3%) was applied to each eye every 15 min for 5 doses and then, every 30 min for 14 doses. The eyes were examined both before and after treatment. The corneas were harvested from treated and untreated rabbits for the quantitation of bacteria and histological observation. In the early-treatment groups, all 3 fluoroquinolones significantly lowered the clinical severity of infection and the median erosion area of the cornea compared with the BSS control (P=0.000). In the late-treatment groups, gemifloxacin and levofloxacin did not cause a significant reduction in clinical scores compared with the BSS control (P=0.107 and 0.531, respectively), but the gatifloxacin caused a significant reduction in clinical scores compared with the BSS control (P=0.011). The median erosion area significantly decreased with treatment with gemifloxacin, gatifloxacin, and levofloxacin in both early- and late-treatment groups, when compared with the control group (P≤0.022). In the early-treatment groups, the gemifloxacin, gatifloxacin, and levofloxacin groups had significantly lower CFU recovered from the corneas compared with the control group (P<0.01), while in the late-treatment groups, levofloxacin failed to reduce the CFU recovered from the corneas compared with the control group (P=0.695). The minimal inhibitory concentrations for gemifloxacin, gatifloxacin, and levofloxacin against S. aureus ATCC25923 were 0.0625, 0.0625, and 0.125 mg/L, respectively. Gemifloxacin, similar to gatifloxacin and levofloxacin, can significantly lower the clinical severity and CFU per cornea observed in S. aureus keratitis when early treatment is implemented. Significantly, gemifloxacin showed a significant efficacy improvement in reducing the bacterial load recovered from the corneas in the late-treatment experiment.

Remote cardioprotection by direct peripheral nerve stimulation and topical capsaicin is mediated by circulating humoral factors

We have previously shown that remote ischemic preconditioning by limb ischemia (rIPC) or intra-arterial adenosine releases a dialyzable cardioprotective circulating factor(s), the release of which requires an intact neural connection to the limb and is blocked by pretreatment with S-nitroso-N-acetylpenicillamine (SNAP). Remote cardioprotection can be induced by other forms of peripheral stimulation including topical capsaicin, but the mechanisms of their signal transduction are incompletely understood. Rabbits were anesthetized by intravenous pentobarbital, intubated and ventilated, then randomized (4-7 animals in each group) to receive sham procedure, rIPC (4cycles of 5min lower limb ischemia, 5min reperfusion), direct femoral nerve stimulation, topical capsaicin, pretreatment with intra-arterial SNAP+capsaicin, pretreatment with topical DMSO (a sensory nerve blocker)+topical capsaicin, or pretreatment with intra-arterial SNAP+femoral nerve stimulation, topical DMSO alone, or intra-arterial SNAP alone. Blood was then rapidly drawn from the carotid artery to produce the plasma dialysate which was used to perfuse a naïve heart from an untreated donor rabbit. The infarct size and recovery of LV-developed pressure and end-diastolic pressure were measured after 30min of global ischemia and 120min of reperfusion. Compared to sham, dialysate from rIPC, femoral nerve stimulation, and topical capsaicin groups all produced significant cardioprotection with significantly reduced infarct size, and improved the post-ischemic cardiac performance. Cardioprotection was not seen in the topical DMSO-capsaicin, SNAP+capsaicin, and SNAP+FNS groups. These results confirm the central role of peripheral nerves in the local signal transduction of remote cardioprotection. Direct electrical or peripheral neural stimulation evokes the release of cardioprotective substances into the bloodstream, with comparable effects to that of rIPC induced by limb ischemia.

The Laser Use in Generating New Species of Medicines with Antitumor and Antibacterial Properties: New Processes in Drug Discovery

-5 M in natural saline which are exposed to coherent or noncoherent light beams. The model simulates the tumor and the tests have shown that conjunctive and neovascularisations disappear after 1-2 treatments. 5-FU is a pyrimidine analog that belongs to the family of antimetabolites. It is weakly fluorescent, but it emits intense fluorescence after exposure to UV-VIS light. The UV-VIS absorption spectra of 5-FU did not show any structural modification after exposure to UV laser beams, but the FTIR spectra showed that the molecular geometry of 5-FU was changed after irradiation. The exposure to UV laser radiation transformed the 5-FU molecule into a tautomeric form. The increase of the fluorescence is attributed to a higher conversion to the keto-enol (lactim form) fluorescing tautomer due to monochromatic and high intensity laser radiation, which allows an effective and selective excitation. The radicals formed by the deprotonation of 5-FU could initiate the tumoricidal effect. The spectroscopic studies were coupled with preliminary tests on 5-FU photosensitizing properties measured on rabbit eyes conjunctive tissues [2]. Comparative data were obtained about the evolution of neovascularisations in the conjunctive tissue between untreated rabbit eyes and eyes impregnated with 5-FU 10 -4 M in natural saline and exposed to a UV-light beam emitted by a nitrogen pulsed laser. These experiments showed that the eye conjunctive inflammation and neovascularisation disappear faster after the treatment, as well. The development of bacteria resistance to antibiotic treatment is of interest. Out of the reports about cytostatics modified by exposure to laser radiation in order to be applied efficiently on tumor tissues in MDR cases we selected two widely utilized chemotherapeutic substances: Methotrexate (MTX) and 5 - Fluorouracil (5 - FU). Methotrexate (MTX) is an antifolate used in the chemotherapy of cancer, as well as in the treatment of psoriasis and rheumatoid arthritis. MTX stops DNA synthesis by inhibiting the action of the dihydrofolate reductase and thus reducing the tetrahydrofolate level in the cell. Studies on the photochemistry of folic acid showed the photodissociation effects of the light on the absorption and fluorescence characteristics of folic acid function of the exposure time [5,6]. MTX belongs to the pterine group, together with folic acid and aminopterine, which form under UV-VIS exposure 6-formylpterine derivates and p-aminobenzylglutamic acid [7].

The initial phase of oxidative stress in a steroid-induced osteonecrosis rabbit model

Using a rabbit model, we examined N epsilon-(hexanoyl) lysine (HEL) levels in bone and urine to detect when peroxidative reaction first occurs after steroid administration. Japanese white rabbits weighing about 3.5 kg each were injected with a single intramuscular dose of methylprednisolone 40 mg/kg and divided into groups consisting of 10 rabbits each, which were killed after 1, 3, 5 and 14 days (groups A, B, C and D respectively). As a control, 10 untreated rabbits (group N) were also studied. The proximal femurs were examined histopathologically and immunohistochemically using monoclonal antibody HEL, which is a highly specific antibody against N epsilon-(hexanoyl) lysine, an early peroxidation marker. In addition, urinary levels of HEL were measured by enzyme-linked immunosorbent assay in group N, A, B and C. Osteonecrosis was detected only in group D (90%). Increase of positive reaction of HEL in the bone was observed in group A and D. HEL expression in group D was judged to be a secondary reaction resulting from the development of osteonecrosis. Urinary level of HEL showed a significant increase in only group A (P < 0.001). The present findings suggest that peroxidation in bone occurred within 24 hours after steroid administration in a rabbit model and that it is possible to noninvasively grasp the timing of this peroxidative reaction by measuring the urinary level of HEL.

Anidulafungin for Neonatal Hematogenous Candida Meningoencephalitis: Identification of Candidate Regimens for Humans Using a Translational Pharmacological Approach

Hematogenous Candida meningoencephalitis (HCME) is a serious infection in premature neonates. Anidulafungin is an echinocandin antifungal agent with potent activity against Candida spp., but its efficacy and optimal regimens for human neonates with HCME are not known. A well-validated rabbit model of HCME was used to define pharmacokinetic-pharmacodynamic (PK-PD) relationships of anidulafungin. A mathematical model was fitted to the entire data set. The experimental data were bridged to humans. A population PK model was fitted to the data from human neonates receiving anidulafungin receiving a loading dose of 3 mg/kg, followed by 1.5 mg/kg/day. Monte Carlo simulations were performed to identify candidate anidulafungin regimens for humans. All untreated rabbits succumbed by ≤96 h postinoculation. The PK of anidulafungin was linear with dose-dependent penetration into the cerebrum. Anidulafungin exerted a rapid antifungal effect that was apparent in the first dosing interval. Near-maximal antifungal activity was observed with dosages of 10 to 20 mg/kg/day. The bridging studies suggested that the current regimen of first 3 mg/kg, followed by 1.5 mg/kg/day, is suboptimal. Higher dosages were associated with progressively greater antifungal effect. Anidulafungin is effective for the treatment of experimental HCME. Higher dosages than those currently used for clinical care are required for maximal antifungal effect.

Abstract 9197: In Situ Stem Cell Therapy Using Human Adipose Tissue-Derived Multi-lineage Progenitor Cells Combined with HMG-CoA Reductase Inhibitor Synergistically Reduce Serum Cholesterol Level in Hyperlipidemic Watanabe Rabbits

Background : Familial hypercholesterolemia (FH) is an autosomal co-dominant disease characterized by high concentrations of pro-atherogenic lipoproteins and premature atherosclerosis. We examined the response to the combination of in situ stem cell therapy using human adipose tissue-derived multi-lineage progenitor stem cells (hADMPC) and HMG-CoA reductase inhibitor in the Watanabe heritable hyperlipidemic (WHHL) rabbit, an animal model of homozygous FH. Methods : WHHL rabbits received hADMPC via the portal vein, followed by a course of immunosuppressive therapy to avoid xenogenic rejection. In situ reprogramming of the hADMPC into hepatocytes was examined by immunohistochemistry and QT-PCR analysis. Lipid profiles were examined before-transplantation, after-transplantation and/or after transplantation followed by 4 weeks of treatment with HMG-CoA reductase inhibitor, pravastatin. LDL clearance was examined at the end of the study by125I-LDL turnover studies. Results : The hADMPC were integrated into the hepatic parenchyma after transplantation, and expressed human hepatocyte markers such as albumin, indicating that these cells were reprogrammed into hepatocytes-like cells in situ . hADMPC-transplantation reduced serum cholesterol levels and improved LDL turnover. Transplantation followed by 4-week treatment with pravastatin further reduced serum cholesterol levels compared with untreated rabbits. LDL clearance was significantly augmented in the pravastatin-treated rabbits. Conclusion : Transplantation of hADMPC corrected the metabolic defects and the effects were augmented by statins in WHHL rabbits, in which no significant effects were observed by statins. In situ stem cell therapy combined with other drugs is a potentially useful strategy for FH.

Efficacy of CG3R6TAT Nanoparticles Self-Assembled from a Novel Antimicrobial Peptide for the Treatment of Candida albicans Meningitis in Rabbits

Background: Candidal meningitis is a common clinical manifestation of invasive candidiasis in neonates. The aim of this study was to evaluate the in vivo antifungal efficacy of CG₃R₆TAT nanoparticles, novel core-shell structures self-assembled from cationic antimicrobial peptides, in a rabbit model of candidal meningitis. Methods: In vitro activity of CG₃R₆TAT nanoparticles against Candida albicans was assessed by determining the minimum inhibitory concentration and kill-time curves. In vivo, intravenous treatment with CG₃R₆TAT nanoparticles (n = 6; 0.25 mg/kg/day) or fluconazole (n = 6; 100 mg/kg/day) began 3 days after infection and continued for 11 consecutive days; the efficacy was assessed following 11 days of treatment by yeast counting in cerebrospinal fluid (CSF), the leukocyte concentrations in CSF and the histopathology of brain parenchyma. Results: At a concentration three times higher than the minimum inhibitory concentration (8.1 µmol/l), the nanoparticles complete- ly sterilized C. albicans after 5 h of incubation. In addition, there was a significant reduction in fungal counts and leukocyte concentrations in the CSF from rabbits treated with CG₃R₆TAT nanoparticles or fluconazole versus those from untreated control rabbits (p < 0.05, ANCOVA). The median number of days of treatment required to sterilize CSF cultures was 8.5 days for CG₃R₆TAT nanoparticle therapy (p = 0.022, vs. control) and 9.7 days for fluconazole therapy (p > 0.05, vs. control). The histopathologic severity of rabbits was significantly attenuated after CG₃R₆TAT treatment (p = 0.001, vs. control). Conclusion: This study suggests that CG₃R₆TAT nanoparticles may be a promising therapeutic agent for candidal meningitis.

Damage caused by low-density exotic herbivore populations: the impact of introduced European rabbits on marsupial herbivores and Allocasuarina and Bursaria seedling survival in Australian coastal shrubland

The impact of over-abundant exotic herbivores is well recognised, but their impact at low population densities is poorly understood. This study examined interactions between European rabbits and native herbivores, and their impact on seedling recruitment in coastal South Australia, 2 years after rabbit haemorrhagic disease (RHD) had reduced rabbit density to 4.48 rabbits ha−1. Rabbit density was further reduced to 0.44 rabbits ha−1 in replicated experimental treatments. Rabbit control reduced total grazing pressure by 39% despite compensatory grazing increases of >100% for both western grey kangaroos and common wombats. Rabbit control slowed the rate of grazing and mortality for planted drooping sheoak and sweet bursaria seedlings, but few survived for 12 months: 0 and 3% of sheoak, in untreated areas and rabbit control treatments, respectively, and 3 and 11% of bursaria, respectively. Planted sheoaks survived well if protected by rabbit-proof netting (60%). Within treatments, seedling grazing and survival rates were negatively correlated with rabbit density but kangaroo and wombat density had no measurable effect. We conclude that RHD may briefly have reduced rabbit densities enough to allow recruitment of bursaria but that sheoak require much lower rabbit densities than those provided by existing biological control agents. If left unaddressed, rabbit grazing could ultimately lead to the loss of sheoaks throughout most of their current range, irrespective of other attempts to conserve them. More generally, these data show how species-specific damage caused by low-density exotic herbivore populations may occur in the presence of more abundant but less-damaging native herbivores.