Effect of limestone solubility on mineral digestibility and bone ash in nursery pigs fed diets containing graded level of inorganic phosphorus or increasing dose of a novel consensus bacterial 6-phytase variant

The effect of a novel consensus bacterial 6-phytase variant (PhyG) on total tract digestibility (ATTD) of minerals and bone ash was evaluated in pigs fed diets containing medium and high solubility limestone (MSL and HSL, 69.6 and 91.7% solubility, respectively, at 5 min, pH 3.0) in a randomized complete block design. For each limestone, 8 diets were formulated: an inorganic phosphate-free negative control (NC) based on wheat, corn, soybean-meal, canola-meal and rice-barn [0.18% standardized total tract digestible (STTD) P and 0.59% Ca]; the NC supplemented with 250, 500, 1,000 or 2,000 FTU/kg of PhyG, and; the NC with added monocalcium phosphate (MCP) and limestone to produce 3 positive controls (0.33, 0.27 and 0.21% STTD P, and 0.75, 0.70 and 0.64% Ca, respectively; PC1, PC2, PC3). In total, 128 pigs (12.8 ± 1.33 kg, 8 pigs/treatment, housed individually) were adapted for 16 d followed by 4 d of fecal collection. Femurs were collected from euthanized pigs on d 21. Data were analyzed by one-way ANOVA with means separation by Tukey’s test, and by factorial analysis (2 x 4: 2 levels of limestone solubility, 4 STTD P levels, and 2 × 5: 2 levels of limestone solubility, 5 PhyG dose levels). Phytase dose-response was analyzed by curve fitting. A consistent negative effect of HSL on ATTD P and Ca was observed in control diets (P < 0.001). Across phytase-supplemented diets, HSL reduced (P < 0.05) ATTD Ca and P (% and g/kg) compared with MSL. Across limestones, increasing phytase dose level increased (P < 0.05) ATTD P exponentially. Limestone solubility had no effect on bone ash, but PhyG linearly increased (P < 0.05) bone ash; 500 FTU/kg or higher maintained bone ash (g/femur) equivalent to PC1. In conclusion, ATTD P and Ca were reduced by a high compared with a medium soluble limestone, but the novel phytase improved ATTD P and Ca independent of limestone solubility.

A novel consensus bacterial 6-phytase variant added to phytate-rich diets totally replaced inorganic phosphate in broilers

The capacity of a novel bacterial 6-phytase variant (PhyG) to totally replace dietary supplemental inorganic phosphate (Pi) in broilers aged one day old was evaluated using a phased dosing strategy and reduction in dietary phytate. A total of 1,248 one-day-old Ross 308 broilers were assigned to 24 pens (52 birds/pen, 12 pens/diet, six each males and females) in a complete randomised block design with a 2×2 factorial arrangement (two diets, two genders). Diets comprised: (1) a positive control (PC) based on maize, wheat and soybean meal, containing Pi from monocalcium phosphate and 2,000 XU/kg xylanase, and; (2) an inorganic phosphate-free (IPF) diet equivalent to PC but with reduced Ca (-2.0 g/kg) and supplemented with PhyG at 3,000, 2,000 and 1000 FTU/kg from d 0 to 11 (3.4 g/kg phytate-P (PP)), d 11 to 22 (3.3 g/kg PP) and d 22 to 42 (2.8 to 2.9 g/kg PP), respectively. A negative control was not included for animal welfare reasons. Tibias were collected on d 11, 22 and 42 from two birds/pen. Treatment IPF maintained or improved average daily gain (ADG), average daily feed intake and feed conversion ratio (FCR) vs PC during all phases; Body weight was higher in the IPF treatment than the PC at d 42 (+3.97%, P<0.01) and ADG during d 0 to 42 (+4.10%, P<0.01). Overall (d 0 to 42), treatment IPF improved FCR in males (-5 points vs PC, P<0.05) but not females. Tibia ash was equivalent in IPF and PC throughout, with no gender differences. In conclusion, when applied as a phased dosing strategy to diets with graded reduction in PP content, PhyG totally replaced supplemental Pi during all growth phases in males and females.

Modeling improvements in ileal digestible amino acids by a novel consensus bacterial 6-phytase variant in broilers

Data from 13 datasets from 4 trials on the effect of a novel consensus bacterial 6-phytase variant (PhyG) on the apparent ileal digestibility (AID) of amino acids (AA) in broilers were used to model AID AA responses. The datasets were obtained from 3 trial locations (New Zealand, Australia and United States) and collectively incorporated variations in diet composition (feedstuff composition, phytate-P (PP) level, limestone solubility), feed form (mash or pellet), bird genetics (strain), and age at sampling (11-35 d of age). In total, 384 observations were analyzed. First, the relationships between AID of AA (as coefficients) and increasing phytase dose level from 0 to 4,000 FTU/kg were evaluated across all datasets using exponential curve fitting. Second, the percentage unit change in AID of AA at each phytase dose level from baseline (basal diet [BD] without phytase) was calculated separately for each dataset and the data then modeled together using exponential curve fitting. The model-predicted mean coefficient of AID of total AA in basal diets was 0.76 (range 0.56 [Cys] to 0.83 [Glu]), which was increased by PhyG to 0.80 and 0.81 at 2,000 and 4,000 FTU/kg, respectively. Exponential increases in the percentage unit improvement in AID of 18 individual and of total AA with increasing phytase dose level were evident (P < 0.05). Improvements (vs. BD) at 2,000 FTU/kg and 4,000 FTU/kg, respectively, were greatest for Cys (+9.2 and +11.0% units), Met (after deduction of synthetic Met, +8.4 and +9.0% units), and Thr (after deduction of synthetic Thr, +6.2 and +7.3% units). The data demonstrated consistent improvements in the AID of AA by the phytase. The modeling results generated from data gathered from birds sampled at different ages and from different dietary settings with correction of synthetic AA for Lys, Met, Thr, and Trp, enabled a more accurate prediction of the digestible AA contribution from the diet by this novel phytase. This will allow diet-specific AA matrix recommendations to be made in commercial feed formulations.

Effects of a novel consensus bacterial 6-phytase variant on the apparent ileal digestibility of amino acids, total tract phosphorus retention and tibia ash in young broilers

The effect of a novel consensus bacterial 6-phytase variant (PhyG) on apparent ileal digestibility (AID) of amino acids (AA) and phosphorus (P) utilization in young broilers when added to diets with high phytate-P (PP) content without added inorganic phosphate (Pi) and deficient in digestible (dig) AA and metabolizable energy (ME) was investigated. A total of 256 Ross 308 male broilers were assigned to 4 treatments (8 birds/cage, 8 cages/treatment) in a completely randomized design. Treatments comprised a positive control (PC, 2,975 kcal/kg ME, 3.7 g/kg dig P, 2.83 g/kg PP, 8.4 g/kg Ca, 10.6 g/kg dig lysine), a negative control (NC) without added Pi (ME −68 kcal/kg, crude protein −10 g/kg, dig AA −0.1 to −0.4 g/kg, Ca −2.0 g/kg, dig P −2.2 g/kg, Na −0.4 g/kg vs. PC), and NC plus 500 or 1,000 FTU/kg of PhyG. Test diets were corn/soy/rapeseed-meal/rice-bran-based and fed from 5 to 15 d of age. Ileal digesta and tibias were collected on day 15. Excreta was collected during days 12 to 15 to determine P retention. The NC (vs. PC) reduced (P < 0.05) P retention (−10.4% units), tibia ash (−14.3% units), weight gain (−109 g), feed intake (−82 g) and increased FCR (from 1.199 to 1.504), confirming that the NC was extremely deficient in nutrients and energy. Phytase addition to the NC linearly (P < 0.001) improved performance, but did not fully recover it to the level of the PC due to the severe nutrients/energy reduction in NC. Phytase linearly increased P retention (P < 0.001), tibia ash (P < 0.001), AID of dry matter (P < 0.05), nitrogen (P < 0.01), gross energy (P < 0.05), and all 17 individual AA (P < 0.01). At 1,000 FTU/kg, phytase increased (P < 0.05) P retention vs. PC and NC (+14.5 and +24.9% units, respectively) and increased tibia ash vs. NC (+13.8% units), equivalent to PC. The NC decreased AID of Cys, Gly, Thr, and Met vs. PC (P < 0.05). At 1,000 FTU/kg, phytase increased AID of all 17 AA vs. NC (P < 0.01), equivalent to PC. At 1,000 FTU/kg, AID AA responses (above NC) ranged from +4.5% (Met) to +15.0% (Cys), being maximal for essential Thr (+10.4%) and Val (+8.2%) and non-essential Cys (+15.0%) and Gly (+10.4%). The results highlight the efficacy of PhyG at a dose level of 500 to 1,000 FTU/kg in young broilers for improving the ileal digestibility of nitrogen, AA, and energy alongside P retention and tibia ash. The performance data emphasize the need to consider digestible nutrient intake as a response variable in exogenous enzyme studies.

Microbial phytase is widely used in commercial broiler diets to improve digestion of phosphorus (P) and reduce its excretion into the environment. Phytase improves the digestion of phosphorus and other nutrients including amino acids (AA). This study evaluated the effect of a novel consensus bacterial 6-phytase variant (PhyG) added to a nutrient-reduced diet without any added inorganic P on the digestibility of nutrients including P and AA in the ileum of young broilers. Effects on P retention and bone mineralization were also assessed. Compared to an unsupplemented negative control diet, PhyG improved growth performance, P retention, bone mineralization (tibia ash), digestibility of dry matter, nitrogen, gross energy, and all 17 individual AA during 5 to 15 d post-hatch, in a dose-dependent manner (dose range 0 to 1,000 phytase units [FTU] per kilogram of feed). For some AA, the increases in digestibility with PhyG at 1,000 FTU/kg were substantial (cysteine: +15.0%, threonine:+10.4%), and for all AA were equivalent to the responses produced by a nutritionally adequate positive control (unsupplemented) diet. The results demonstrate the efficacy of PhyG to improve AA digestibility alongside growth performance, P retention, and bone mineralization in young broilers.

Effect of increasing dose level of a novel consensus bacterial 6-phytase variant on phytate degradation in broilers fed diets containing varied phytate levels

1. The effect of increasing the dose level of a novel consensus bacterial 6-phytase variant on apparent ileal digestibility (AID) of phosphorus (P), phytic acid (inositol hexa-phosphate, IP₆) and ileal IP₆ degradation profile was studied in diets containing varying phytate-P (PP) levels.2. Ross 308, one-day-old males (n=1,800) were allocated to cages (20 birds/cage, six cages/treatment) in a completely randomised design employing a 3 × 5 factorial arrangement (three PP levels: 2.45 (low) 2.95 (medium) and 3.45 g/kg (high); five dose levels of phytase (PhyG): 0, 500, 1,000, 2,000 and 4,000 FTU/kg). Phased diets were based on wheat, corn, soybean meal, rapeseed meal and rice bran (d 0 to 10; 2.60 g/kg digestible P, 7.6 g/kg calcium (Ca); d 11 to 21; 2.10 g/kg digestible P, 6.4 g/kg Ca). Ileal digesta was collected on d 21 for determination of P, IP₆ and IP-esters content. Data were analysed by factorial ANOVA; means separation was achieved using Tukey's HSD test.3. Increasing PP reduced AID of IP₆ and sum of IP_3-6 (%) (P<0.05) but absolute P-release (g/kg diet) above NC was increased (P<0.05) at high vs. low PP. Increasing phytase dose exponentially increased (P<0.001) AID IP_6, sum of IP_3-6 (%) and digestible IP_3-6-P g/kg diet (P<0.001). AID P was increased but there was an interaction with PP level (P<0.001). Ileal accumulation of IP_5-3-P was universally low with PhyG at ≥1,000 FTU/kg (<0.06 g/100g DM). At 2,000 and 4,000 FTU/kg, AID IP₆ was 97.2, 92.7, 92.6% and 100, 97.2, 97.1%, respectively, at low, medium and high PP. At 2,000 FTU/kg, phytate-P release estimated as the increase (above NC) in ileal digestible sum of IP_3-6-P in the diet was 2.26, 2.59 and 3.10 g/kg in low, medium and high PP, respectively.4. The data demonstrated that the novel phytase was effective in breaking down phytate to low IP-esters in diets with varied PP content but the optimal dose level for maximising P-release may differ in diets with varying PP content.

Nerve-specific extracellular matrix hydrogel promotes functional regeneration following nerve gap injury

Nerve transection requires surgical intervention to restore function. The standard of care involves coaptation when a tension-free repair is achievable, or interposition of a graft or conduit when a gap remains. Despite advances, nerve gap injury is associated with unsatisfactory recovery. This study investigates the use of a decellularized, porcine nerve-derived hydrogel filler (peripheral nerve matrix, PNM) for conduits in an 8 mm rat sciatic nerve gap model. The decellularized tissue maintained multiple nerve-specific matrix components and nerve growth factors. This decellularized tissue was used to formulate hydrogels, which were deployed into conduits for nerve gap repair. Nerve recovery was assessed up to 24 weeks post injury by gait analysis, electrophysiology, and axon counting. Deployment of PNM within conduits was shown to improve electrophysiologic response and axon counts compared with those of empty conduit controls. These results indicate that PNM has potential benefits when used as a filler for conduits in nerve gap injuries.

Effect of a novel consensus bacterial 6-phytase variant in grower pigs fed corn-soybean meal-based diets formulated with a full nutrient matrix and no added inorganic phosphorus

The capacity of a novel consensus bacterial 6-phytase variant (PhyG) to entirely replace dietary inorganic phosphorus (Pi) source in grower pigs fed diets with reduction of calcium (Ca), net energy (NE), and digestible amino acids (AA) was evaluated, using growth performance and apparent total tract digestibility (ATTD) of nutrients as outcome measures. A total of 352 mixed-sex pigs (initial BW 23.4 kg) were randomized to 4 treatments, 8 pigs/pen, and 11 pens/treatment. Diets were corn-soybean meal-based and formulated by phase (grower 1, 25 to 50 and grower 2, 50 to 75 kg BW). The positive control diet (PC) provided adequate nutrients and a negative control diet (NC) was formulated without Pi (1.2 g/kg ATTD P) and reduced in Ca (-0.12 to -0.13 percentage points), NE (-32 kcal/kg), and digestible essential AA (-0.004 to -0.026 percentage points) vs. PC. Two further treatments comprised the NC plus 500 or 1,000 FTU/kg of PhyG. Data were analyzed by ANOVA, mean contrasts and orthogonal polynomial regression. Nutrient reductions in the NC reduced (P < 0.05) average daily gain (ADG) during grower 1 and overall (73 to 136 d of age), increased (P < 0.05) feed conversion ratio (FCR) during grower 1 and overall and tended to reduce (P < 0.1) average daily feed intake (ADFI) during grower 2 and overall, vs. PC. Phytase supplementation improved (P < 0.05) FCR during grower 1, ADG during grower 2 and overall, ATTD of DM and P, and tended to improve DE (P = 0.053) in a linear dose-dependent manner. PhyG at 1,000 FTU/kg resulted in growth performance (all measures, all phases) equivalent to PC. The findings demonstrate that PhyG at 1,000 FTU/kg totally replaced Pi in complex grower pig diets containing industrial co-products, compensated a full nutrient matrix reduction and maintained performance.

A novel consensus bacterial 6-phytase variant completely replaced inorganic phosphate in broiler diets, maintaining growth performance and bone quality: data from two independent trials

Total replacement of dietary inorganic phosphate (Pi) by a novel consensus bacterial 6-phytase variant (PhyG) in phytate-rich diets (>0.3% phytate-P) was investigated in 2 trials using growth performance and bone quality as outcome measures. Both trials utilized a completely randomized design with 5 dietary treatments across 4 phases: starter (0-10 d), grower (10-21 d), finisher 1 (21-35 d), and finisher 2 (35-42 d). Treatments comprised a nutritionally adequate positive control (PC) diet containing monocalcium phosphate and 4 experimental diets (IPF1, IPF2, IPF3, and IPF4), all containing no added Pi and reduced in Ca by 0.2 to 0.3% units vs. PC. IPF1contained PhyG at 1,000 FTU/kg (all phases); IPF2 contained PhyG at 1,000 FTU/kg (all phases) and was additionally reduced in digestible AA, ME, and sodium (-0.2 to -0.4% points, -74 kcal/kg, -0.04% points, respectively, vs. PC); IPF3 contained PhyG at 3,000 FTU/kg in starter, 2,000 FTU/kg in grower, and 1,000 FTU/kg in finisher phases; and IPF4 contained xylanase (2,000 U/kg) and PhyG (2,000 FTU/kg in starter, 1,500 FTU/kg in grower, and 1,000 FTU/kg in finisher phases) and was additionally reduced in ME (-71 kcal/kg vs. PC). Ross 308 broilers were used (trial 1: n = 1,200 mixed sex; 24 birds per pen × 10 replicates; trial 2: n = 1,300 males; 26 birds × 10 replicates). During all phases in both trials, all IPF treatments maintained or improved BW, ADG, ADFI, FCR and BW-corrected FCRc and bone quality parameters vs. PC. vs. PC, treatment IPF3 increased ADG during starter phase (+10.8%) and reduced overall FCRc (-12 points, P < 0.05) in Trial 1, and increased overall ADG (+4.4%), day 35 and day 42 BW (+3.5%, +4.9%), and reduced overall FCRc (-11 points) in Trial 2 (P < 0.05). IPF4 produced equivalent performance to IPF3 (both trials). These are the first data to demonstrate total replacement of Pi by microbial phytase during an entire growth cycle in broiler diets.

Buttiauxella phytase maintains growth performance in broilers fed diets with reduced nutrients under a commercial setting

The effect of down specifying nutrients in diets supplemented with Buttiauxella spp. phytase was studied in a commercial trial. Three treatments were tested with five replicate groups, each containing 700, one-day-old straight run Ross 308 broilers. Birds were fed pelleted diets from days 0-42 in four phases: starter (days 0-10); grower (days 11-21); finisher 1 (days 22-35) and finisher 2 (days 36-42). A nutritionally adequate, unsupplemented, positive control (PC) diet based on wheat, corn and soybean meal was compared against two down specified, negative control (NC) diets containing Buttiauxella phytase supplemented at 500 or 1000 FTU/kg. The reduction level was 0.134 and 0.159% unit for digestible phosphorus, 0.164 and 0.189% unit for calcium, 0.03 and 0.04% unit for sodium, 0.283 and 0.309 MJ/kg for nitrogen corrected apparent metabolizable energy in all phases and variable digestible amino acids in different phases, respectively for the diets containing the phytase at 500 and 1000 FTU/kg. An unsupplemented NC diet was not included, as it would have caused welfare and health issues. Weight gain and mortality-corrected feed conversion ratio for birds receiving phytase at either inclusion levels were equivalent to the PC group. Feed intake was increased by 500 FTU/kg phytase (P<0.05) during 0-21 d vs PC. Including 1000 FTU/kg phytase reduced water intake vs PC at 0-42 d and water-to-feed intake ratios, after the starter phase (P<0.05). Carcass yield in birds supplemented with either phytase level was not different from PC. Tibia ash was unaffected by treatment. Estimated feed costs (inclusive of phytase) were lower in supplemented than un-supplemented (PC) diets, by 10.0 to 13.7 €/ton diet. The trial demonstrated that reducing nutrient specifications of diets supplemented with Buttiauxella phytase maintained growth performance, lowered feed costs, with production benefits maximised at inclusion levels of 1000 FTU/kg.

Screening of freshwater and seawater microalgae strains in fully controlled photobioreactors for biodiesel production

Strain selection is one of the primary hurdles facing cost-effective microalgal biodiesel production. Indeed, the strain used affects both upstream and downstream biodiesel production processes. This study presents a screening procedure that considers the most significant criteria in microalgal biodiesel production including TAG production and wet extraction and recovery of TAGs. Fourteen freshwater and seawater strains were investigated. Large variation was observed between the strains in all the screening criteria. The overall screening procedure ultimately led to the identification of Parachlorella kessleri UTEX2229 and Nannochloropsis gaditana CCMP527 as the best freshwater and seawater strains, respectively. They featured the largest areal TAG productivity equal to 2.7×10(-3) and 2.3×10(-3)kgm(-2)d(-1), respectively. These two strains also displayed encouraging cell fragility in a high pressure bead milling process with 69% and 98% cell disruption at 1750bar making them remarkable strains for TAG extraction in wet environment.

Optimization of bead milling parameters for the cell disruption of microalgae: process modeling and application to Porphyridium cruentum and Nannochloropsis oculata

A study of cell disruption by bead milling for two microalgae, Nannochloropsis oculata and Porphyridium cruentum, was performed. Strains robustness was quantified by high-pressure disruption assays. The hydrodynamics in the bead mill grinding chamber was studied by Residence Time Distribution modeling. Operating parameters effects were analyzed and modeled in terms of stress intensities and stress number. RTD corresponded to a 2 CSTR in series model. First order kinetics cell disruption was modeled in consequence. Continuous bead milling was efficient for both strains disruption. SI-SN modeling was successfully adapted to microalgae. As predicted by high pressure assays, N. oculata was more resistant than P. cruentum. The critical stress intensity was twice more important for N. oculata than for P. cruentum. SI-SN modeling allows the determination of operating parameters minimizing energy consumption and gives a scalable approach to develop and optimize microalgal disruption by bead milling.

Selective extraction from microalgae Nannochloropsis sp. using different methods of cell disruption

This work studies the extraction of intracellular components from microalgae Nannochloropsis sp. with application of different cell disruption techniques, including pulsed electric field (PEF) (20kV/cm, 1-4ms, 13.3-53.1kJ/kg), high voltage electrical discharge (HVED) (40kV/cm, 1-4ms, 13.3-53.1kJ/kg), ultrasonication (USN) (200W, 1-8min, 12-96kJ/kg), and high pressure homogenization (HPH) (150MPa, 1-10 passes, 150-1500kJ/kg). The data evidence that electrically based disruption techniques (PEF and HVED) allowed selective extraction of water soluble ionic components and microelements, small molecular weight organic compounds and water soluble proteins. Microscopic and sedimentation stability analyses have shown that microalgae cells in HVED-treated suspension were noticeably agglomerated and could be easily settled in centrifuge. The electrically based disruption techniques were ineffective for delivery of pigments (e.g., chlorophylls or carotenoids) and their extraction required subsequent application of more potent disruption techniques. The obtained data have shown that HPH disruption technique was the most effective; however, this mode required the highest power consumption.

Interest of second harmonic generation imaging for diagnosis in thick and opaque tissue

In articular hyaline cartilage, chondrocytes are surrounded by an extracellular matrix which is mainly composed by collagen and proteoglycanes. Pathological specimens show a partial or complete degradation of this matrix. Therefore, it could be interesting to know how mechanical or biochemical constraints applied to cartilage specimens induce modifications of the cartilage network. Multiphoton technology combined to Second Harmonic Generation (SHG) enables to image cartilage specimens in a non-invasive mode with high resolution at deep penetration. By placing a band pass filter in front of the transmitted light detector, SHG signal with frequency doubled can be isolated for a new contrast imaging. SHG (second harmonic generation) is a diffusion process generated from organized structures and does not need any fluorescent staining. Due to their non-centrosymetric structure, collagen fibrilles present a high second-order non-linear susceptibility and thus give rise to a strong SHG signal when exposed to high enough electric fields produced by a focal point of a femtosecond pulsed laser (multiphoton microscopy). As the extracellular matrix of cartilage is in part constituted by collagen fibers, it can be imaged with this contrast tool. The intensity of SHG signals strongly depends on the organization of collagen fibers. Thus a modification of the extracellular matrix in terms of 3D-organization of collagen induced by mechanical stress can be shown with this contrast tool.

Influences of construct properties on the proliferation and matrix synthesis of dedifferentiated chondrocytes cultured in alginate gel

To investigate whether the chondrocytes-alginate construct properties, such as cell seeding density and alginate concentration might affect the redifferentiation, dedifferentiated rat articular chondrocytes were encapsulated at low density (LD: 3 x 10(6) cells/ml) or high density (HD: 10 x 10(6) cells/ml) in two different concentrations of alginate gel (1.2% or 2%, w/v) to induce redifferentiation. Cell viability and cell proliferation of LD culture was higher than those of HD culture. The increase in alginate gel concentration did not make an obvious difference in cell viability, but reduced cell proliferation rate accompanied with the decrease of cell population in S phase and G2/M phase. Scan electron microscopy observation revealed that chondrocytes maintained round in shape and several direct cell-cell contacts were noted in HD culture. In addition, more extracellular matrix was observed in the pericellular region of chondrocytes in 2% alginate culture than those in 1.2% alginate culture. The same tendency was found for the synthesis of collagen type II. No noticeable expression of collagen type I was detected in all constructs at the end of 28-day cultures. These results suggested that construct properties play an important role in the process of chondrocytes' redifferentiation and should be considered for creating of an appropriate engineered articular cartilage.

Multiphoton microscopy for blood vessel imaging: new non-invasive tools (Spectral, SHG, FLIM)

Imaging thick and opaque tissue, like blood vessel, in a noninvasive mode with high resolution, is nowadays possible with multiphoton technology. A near-infrared excitation presents the advantage to be compatible with living specimens and allows a deep penetration into tissues. The nonlinear excitation process is followed by several deactivation ways, among which fluorescence emission can be represented with Spectral or Lifetime imaging. Applied to ex vivo blood vessel imaging, these techniques enabled us to discriminate cell structures (nucleus, cytoskeleton) by fluorescent labelling (Hoechst, QDots). Another method, based on 2-photon excitation and which doesn't need any exogenous dye has also been experimented on arteries: SHG (Second Harmonic Generation) is a diffusion process generated from organized structures. Collagen molecules give rise to a strong SHG signal, enabling us to image the arterial wall (3-dimensional extracellular matrix).

Decellularized umbilical artery treated with thin polyelectrolyte multilayer films: potential use in vascular engineering

Decellularized allograft tissues have been identified as a potential extracellular matrix scaffold for tissue-engineered vascular substitutes. In order to improve the thromboresistance, it is necessary to pre-coat the intra-luminal vessel surface. Recently a new surface modification technique appeared, based on the alternate adsorption of positive and negative charged polyelectrolytes. Our objective was to develop an alternative vascular scaffold made of decellularized human umbilical arteries treated with a PAH/PSS polyelectrolyte multilayered film. The vessels luminal surfaces covered with the multilayer film were observed by electronic scanning microscopy. Our observations showed that the luminal surface is completely devoid of ECs following treatment with trypsin. A top view of the coated artery indicated that the multilayer uniformly covered internal surface of the vessels. The successful of the multilayer correct deposition and retention on the arterial wall were controlled by confocal microscopy using a fluorescent polyelectrolyte (rhodamine-PAH). The data suggest that decellularized cryopreserved arteries represent a potential scaffold for further vascular tissue engineering efforts. Moreover, the multilayer films can be used to coat biological surfaces and following the terminated layer (PAH or PSS), favour the cell adhesion or cell resistance.

The risk of post-operative complications associated with infliximab therapy for Crohn's disease: a controlled cohort study

BACKGROUND

By temporarily suppressing the immune response, the anti-tumour necrosis factor agent, infliximab, may increase the risk of peri-operative complications.

AIM

To test this hypothesis for intestinal resection in a cohort of 313 Crohn's disease patients treated with infliximab. Forty received one or more infusions prior to intestinal resection (31/40 within 12 weeks).

METHODS

The post-operative events of these patients were compared with those of a control group (infliximab naive) of 39 patients adjusted for age, gender and surgical procedure. Early (10 days) and late (3 months) major or minor complications were identified.

RESULTS

The incidence of early minor (15.0% vs. 12.8%) and major (12.5% vs. 7.7%) and late minor (2.5% vs. 5.1%) and major (17.5% vs. 12.8%) complications and the mean hospital stay after surgery (10.3 +/- 4.0 days vs. 9.9 +/- 5.5 days) were similar in both groups. A trend towards an increased early infection rate was found in infliximab pre-treated patients (6 vs. 1; P = 0.10), but more patients in this group received corticosteroids and/or immunosuppressives (29 vs. 16 patients; P < 0.05).

CONCLUSION

The use of infliximab before intestinal resection does not prolong the hospital stay and does not increase the rate of post-operative complications.

Nerve anastomosis with glue: comparative histologic study of fibrin and cyanoacrylate glue

The authors report the results of a comparative experimental nerve study, using a biologic tissue glue (fibrin) and a synthetic glue (2-cyanoacrylate) in a rat model. A tension-free repair is necessary with the use of fibrin glue, or gapping may occur, thus limiting the use of the agent in promoting re-neurotization. In addition, the human origin of fibrin and thrombin allow for the possibility of viral transmission. The aim of the study was to verify if the synthetic glue is a viable alternative, or whether it causes cellular and tissue lesions. Their main finding was that the cyanoacrylate causes a foreign-body inflammatory reaction and retractile fibrosis, often reducing the nerve diameter up to two-thirds. Cyanoacrylate glue is thus not recommended for peripheral nerve repair.

Bactericidal properties of the chloroform fraction from rhizomes of Aristolochia paucinervis Pomel

The deffated chloroform fraction (APRC) obtained from the rhizomes of Aristolochia paucinervis Pomel (Aristolochiaceae) has a high bacteriostatic activity against bacterial strains like Clostridium perfringens ATCC 13124 and Enterococcus faecalis ATCC 29212. Here, we report the bactericidal activity of APRC against both strains which was evaluated by using time-to kill assays. The results showed that APRC produced an intense time-dependent bactericidal effect against C. perfringens, achieving over a 24 h-period a 5log10-unit decrease in CFU/ml at a concentration > or =1.25 x MIC. In contrast, when tested against E. faecalis, APRC exhibited a concentration-dependent killing activity at concentrations of 1.25 x MIC and 2.5 x MIC, yielding to a decrease of 1.5 and 2.5log10-unit in CFU/ml at 4 h, respectively. However, substantial regrowth of E. faecalis occurred within 24 h. Ultrastructural alterations were observed for both exposed microorganisms by scanning and transmission electron microscopy.

Evaluation of low-pressure arterial and venous clamps: electron microscopic study and possible clinical applications

These authors report on validating their choice of disposable clamps in arterial and venous microsurgery in a comparative and experimental study using the scanning electron microscope. This appears to be the first evaluation of venous endothelial clamping lesions. Early intimal clamping lesions were studied using three different clamps and two protocols in 18 femoral arteries and veins in rabbits. Results were evaluated using a new classification that can be applied to both arterial and venous lesions: Grade I: cellular disorientation and disorganization; endothelial lamination; and absent or very few platelet deposits; Grade II: alterations of the cytoplasmic membranes in fusiform cells; presence of at least one breach of endothelial continuity; and moderate number of platelet deposits; Grade III: presence of endothelial detachment; and large numbers of platelet deposits. They showed that in arteries, all the clamps tested caused only low-grade lesions. In contrast, in veins, they demonstrated both the very fragile nature of the endothelium, and also the comparative safety of the low-pressure venous clamp. Their choice of specific clamps for venous anastomoses was validated.

Influence of flow patterns on chromatographic efficiency in centrifugal partition chromatography

Visualization of flow patterns in centrifugal partition chromatography (CPC) was performed with an asynchronous camera and a stroboscope triggered by the CPC rotor, allowing a channel to be selected and observed regardless of rotational speed. Three main types of flow states were noted as a function of rotational speed and flow-rate: jets stuck along channel walls, broken jets and atomization. Our observations emphasize the importance of Coriolis force on flow shape. Chromatographic efficiency was related to the dispersion of the mobile phase in the stationary phase.

Histologic changes in the sinus membrane after maxillary sinus augmentation in goats

PURPOSE

Previous studies have reported on the morphologic aspects of bone regeneration after maxillary sinus grafting. However, no previous studies have examinated the morphology of the maxillary sinus mucosa after grafting. The purpose of this study was to evaluate the histologic changes in the lining membrane after sinus augmentation.

MATERIALS AND METHODS

A unilateral osteotomy of the lateral maxillary wall, medial displacement of the bony segments, and elevation of the sinus mucosa were performed in 12 goats. An autogenous bone graft combined with coralline particles was placed on the floor of the sinus in three animals, and coralline particles alone were placed in three other goats. Six goats were not grafted and were used as controls. Samples were harvested at 2.5, 4.5, and 6.5 months. The maxillary sinus mucosa was examined using light microscopy and scanning and transmission electronic microscopy.

RESULTS

The coralline particles were surrounded by fibrous connective tissue when used alone. The addition of iliac crest bone to the coralline particles stimulated bone formation. After the sinus augmentation, the mucosal lining showed a lack of glands in the lamina propria, and the epithelium showed an increase in goblet cells.

CONCLUSION

It was concluded that the sinus mucosa undergoes physiologic adaptations and remains healthy and free of chronic sinusitis after maxillary sinus grafting.

Fertility after radical surgery for tubal pregnancy

OBJECTIVE

To evaluate fertility after salpingectomy performed for ectopic pregnancies (EPs).

DESIGN

Retrospective cohort study.

SETTING

Tertiary care university hospital.

PATIENT(S)

Three hundred forty patients (213 with surgery by laparoscopy and 127 by laparotomy) between January 1985 and July 1994, with a mean follow-up period of 73 months (36-162 months).

INTERVENTION(S)

Salpingectomy performed either by laparotomy or by laparoscopy as indicated.

MAIN OUTCOME MEASURE(S)

Rate of intrauterine pregnancy (IUP), live births, and recurrent EP.

RESULT(S)

Forty-seven (13.8%) patients were lost to follow-up, and 68 (20%) did not want to become pregnant. The overall rate of spontaneous conception was 70.4% in the laparoscopy group and 53.2% in the laparotomy group. The rate of live births was 50% and 37%, respectively; the mean time until conception was 11 and 17.2 months; and the rate of recurrent EP, 10.6% and 9.6%. The multivariate analysis showed a rate of IUP of 82.1% among women younger than 30 years of age with a normal contralateral tube, laparoscopic surgery, and no history of infertility.

CONCLUSIONS

In this study of fertility after salpingectomy for EP, laparoscopic treatment was superior to laparotomic treatment. Fertility was equivalent to that after conservative treatment in a subgroup of young patients treated with laparoscopy and with no history of tubal pathology.

The effects of aluminum, iron, chromium, and yttrium on rat intestinal smooth muscle in vitro

The modification of peristaltic activity in the presence of several metal ions has been investigated in the rat intestine by the isolated organ technique. The metals tested modify the intestinal movements: aluminum, chromium, and yttrium cause a decrease of amplitude, while iron showed no effect. By use of microscopic techniques, the presence of yttrium hydroxide was observed in the intestinal tissues. Iron also appears as a precipitate outside of the intestinal serosal, which may explain why iron did not modify the peristaltism. Chromium and aluminum were not apparent to microscope, despite being detected and quantified in the tissues by means of atomic emission spectrometer. We conclude that the trivalent ions of these elements may operate differently on the mechanisms of intestinal contractions: yttrium precipitates in intercellular spaces, iron precipitates outside the intestines, and chromium and aluminum remain in solution and are distributed homogeneously in the smooth intestinal muscle.

In vitro colonization ability of human colon mucosa by exogenous Lactobacillus strains

We have tested five Lactobacillus strains for their in vitro colonization ability in a human colon epithelium culture model. Positive colonization occurred in different degrees in the presence of four Lactobacillus strains. We have found that L. casei GG and L. acidophilus NCFB 1748 induce an intermediate colonization. These two strains, largely investigated by others, have been reported to be beneficial to humans. The use of human intestinal tissue in our study partially reconstitutes the complex architectural specificity of human epithelium with the mucus layer and more closely simulates the in vivo situation.

[Scanning electron microscopy and microcrystals in articular diseases]

The value of scanning electron microscopy (SEM) in the study of crystals in articular diseases is underlined in several cases of examination of joint fluid, or crystal deposits in articular or periarticular tissues obtained by percutaneous or surgical treatment with chemical and crystallographic correlations. Apatite crystals. Two deposits of hydroxyapatite of the rotator cuff were studied by SEM, crystallographic techniques and chemical analysis. SEM study showed spherical aggregates of various size. Urate crystals. Three tophi were observed by SEM, with crystallographic techniques and chemical analysis. Their needle-shape and their great size (20 m) were characteristic. Calcium pyrophosphate crystals. In a case of typical clinical and radiological features, examination of joint fluid, with chemical correlation showed shorter and thicker crystals than those or urate. The precise identification of crystals is based on sophisticated crystallographic techniques such as X-ray diffraction, although SEM allows an accurate and quite simple morphologic study, most often sufficient.

[DIfferentiation of enthesis and the synovial membrane in the rat]

The development of the knee joint in Wistar rats was observed from the 14th fetal day to the 40th postnatal day by light microscopy, transmission electron microscopy and scanning electron microscopy. The differentiation of the capsular ligamentous and tendinous attachments, synovial cavity, and A and B cells were particularly compared. Capsular attachments appeared for the first time at the 15th day of fetal life. The formation of the cavity started at the 17th day of fetal life. The differentiation of A and B cells was observed by the 20th fetal day by T.E.M., and only by the 15th postnatal day by S.E.M.

[Surgical debridement of epicondyles. A 10-year follow up of 100 cases]

A single method was used in all cases: debridement of the radial head and exeresis of the apophysis. The statistics presented are derived from 100 elbows operated in 90 patients between 1970 and 1988. Fifty-four (54%) of the patients were men. Thirty-one (31) of the patients regularly took part in sport. Eighty-seven (87) cases were subjected to histopathological examination. Eighty-two (82) showed major signs of insertion tendinitis. With a mean follow-up of 7 years 4 months, the rate of good or very good results was 88% in subjective terms and 85% in objective terms. It was possible to examine 34 elbows on two occasions, 4 and 12 years after the surgery. No long-term self-deterioration or recurrence was observed. Fair or poor results were obtained in cases of malingerers claiming occupational accident, patients who had too quickly recommended physically demanding work, and cases associating other lesions (cervico-brachial neuralgia, epitrochleitis). All of these cases involved dubious indications for surgery. To conclude, this method is obviously intended only for cases in which medical treatment has been unsuccessful (and these are unusual). In nearly 9 out of 10 such cases, the procedure achieves an improvement.

Scanning electron microscopy (SEM) of the human thyroid gland: a technical improvement for follicular cell observation

SEM is a valuable tool for the examination of hollow organ free surfaces. It has been used in a few studies of human thyroid. The cell surface observation is usually limited by the presence of colloid in the follicular lumen. A technique of direct removal of the colloid has been previously proposed. It gives good morphological results. But this method needs preliminary fixation and critical point drying of thyroid samples. Antigenic properties of tissue blocks are then unsuitable for further staining. We describe a fast and easy technique for colloid removal by washing thyroid samples in a saline solution. Colloid is correctly removed from the tissue block surface prior to fixation. Apical cells are left undamaged. The exposure of thyroid blocks to ultrasound did not improve colloid removal. A post-fixative chemical drying in hexamethyldisilazane shortens processing time. We have studied the efficiency of this technique on 24 human thyroid samples obtained by surgery (normal tissue, Grave's disease, heteromultinodular goiter, toxic solitary adenoma). All specimens were observed by SEM and transmission electron microscopy in order to assess the good preservation of cell surface details. This easy technique could be used as a routine process.

[A single-use vascular clamp. An experimental and clinical study]

Twelve rabbit femoral arteries were clamped for one hour with a TKS2 clamp in order to confirm the atraumatic nature of the Tamai disposable clamp. After 15 or 30 minutes of revascularisation, the arteries were excised and studied by light microscopy and scanning electron microscopy. Temporary dilatation of the artery was observed after removal of the clamp, as the patency test was always positive. Light microscopy revealed parietal flattening without any cellular disorganisation and scanning electron microscopy revealed flattening of the endothelial cells without any tearing. On the basis of these favourable results, combined with the ease of use, we now use the Tamai clamp daily.

[Scanning electron microscopy study of the lung]

The pulmonary parenchyma is characterized by a marked development of blood-tissue and gaz-tissue interfaces. Thus the study of the lung is easy by scanning electron microscopy. Numerous and various technics of sample preparation are described and discussed. They permit to carry out morphological and morphometrical studies of fine structures in the adult and foetal lung surface. The systematisation of the different parts of the pulmonary air tract (bronchi, bronchioli, alveolar ducts and alveoli) is analysed. The different epithelial cells are characterized by their apical differentiations and by their often specific localization. Bronchial (mucus), bronchiolar and alveolar (surfactant) secretions are studied after different fixations. The observation of the vascular network (arteries, veins and pulmonary capillaries) is performed after vascular injection of fixator liquid. The scanning electron microscope is also used to study the alveolar macrophage (in situ or in cell culture), the visceral surface of pleura, the pre and post-natal development of the lung parenchyma. The SEM is a complementary and modern method of lung observation. It gives a dynamic view of the fine structure of lung surfaces, which appears needful for the study of the local histophysiological processes.

Inhibitory effects of the graft versus host reaction upon the development of the bursa of Fabricius. Early modifications in the subepithelial mesenchyma

The graft versus host reaction elicited in the chick embryo by lymphoid cells from a homologous adult donor is known to alter the histogenesis of the bursa of Fabricius. This paper reports the first scanning and transmission electron microscope studies of this phenomenon. Of the three main bursal components (lymphoid lineage, endodermic epithelium and mesenchyma), the subepithelial mesenchyma (SEM) exhibits the earliest and the most obvious modifications. There is a concomitant decrease of SEM alkaline phosphatase activity. It is suggested that disorganization of the SEM, which is a normal pathway of migration for the lymphoid precursors, reduces the inflow of these cells into the epithelial compartment.