Differences In Fiber Diameter Research Articles

Investigating long term storage stability and drug release behavior of polypeptide based fibrous scaffold for tissue engineering application

Electrospun poly (γ-benzyl-l-glutamate) (PBG) scaffold felt with aligned fibers shows promising nerve regeneration and neurite growth capability due to the nerve stimulating moiety of glutamate in the PBG material. The nerve regeneration capability can be further enhanced by incorporating 4 wt% minocycline hydrochloride (MH) in the scaffold (PBGMH4). They are useful in the nerve tissue engineering to repair and regeneration damaged nerves in central nerve system or peripheral nerve system. Here we investigate the ambient storage capability of PBG and PBGMH4 by monitoring the changes over time of fiber dimension, mechanical properties of both scaffolds and amount of drug release of PBGMH4. It is interesting to observe the diameter of fibers and mechanical strength of scaffolds increases but the amount of drug release decrease with time. By carefully examining the top view of the scaffolds using scanning electron microscopy (SEM), the fiber diameter of PBG increased by 58 % over the 12 months storage period, which is larger than the 32 % increase observed for PBGMH4. Furthermore, after storage for 12 months, the difference in fiber diameter between the top and bottom sides of PBG scaffold is 25.9 %, whereas for PBGMH4 is only 6.3 %. These results demonstrate that the PBGMH4 scaffold exhibits superior storage stability compared to that of PBG. Because the fibers of the scaffolds are aligned without any crosslinkage, the scaffolds are porous structure of felts. The porosity of PBGMH4 scaffold is decreased from 90 % to 72 % which can be accountable for the decrease of drug release from initial 42 % to a stabilized 26 % after 9 months of storage. The results indicate the specific surface area of the scaffolds play an important role in governing drug release kinetics. This study thoroughly investigates the storage stability of PBG and PBGMH4 electrospun fibrous scaffolds. The observed correlations between fiber diameter, mechanical properties, and drug release behavior hold implications for the design of advanced bioscaffolds. The long shelf life of optimal PBGMH4 scaffold shows potential application for the nerve regeneration and controlled drug delivery systems.

Integration Analysis of Hair Follicle Transcriptome and Proteome Reveals the Mechanisms Regulating Wool Fiber Diameter in Angora Rabbits.

Fiber diameter is an important characteristic that determines the quality and economic value of rabbit wool. This study aimed to investigate the genetic determinants of wool fiber diameter through an integration analysis using transcriptomic and proteomic datasets from hair follicles of coarse and fine wool from Angora rabbits. Using a 4D label-free technique, we identified 423 differentially expressed proteins (DEPs) in hair follicles of coarse and fine wool in Angora rabbits. Eighteen DEPs were examined using parallel reaction monitoring, which verified the reliability of our proteomic data. Functional enrichment analysis revealed that a set of biological processes and signaling pathways related to wool growth and hair diameter were strongly enriched by DEPs with fold changes greater than two, such as keratinocyte differentiation, skin development, epidermal and epithelial cell differentiation, epidermis and epithelium development, keratinization, and estrogen signaling pathway. Association analysis and protein-protein interaction network analysis further showed that the keratin (KRT) family members, including KRT77, KRT82, KRT72, KRT32, and KRT10, as well as CASP14 and CDSN, might be key factors contributing to differences in fiber diameter. Our results identified DEPs in hair follicles of coarse and fine wool and promoted understanding of the molecular mechanisms underlying wool fiber diameter variation among Angora rabbits.

White epaxial muscle aerobic and anaerobic potential and muscle fiber structure in surface and cave morphotypes of the Mexican cavefish (Astyanax mexicanus).

Proper muscle function and muscle fiber structures that match the environmental demands of organisms are imperative to their success in any ecosystem. The Mexican cavefish, Astyanax mexicanus, has two morphotypes: an obligate cave-dwelling form that lives in thermally insulated caves and an O2 poor environment, and a surface form that lives in a more thermally variable, but O2 rich river environment. As environment can determine physiological adaptations, it is of interest to compare the aerobic and anaerobic metabolic profiles of white muscle metabolism in both morphotypes of this species, as well as their muscle structures. Here, we used white muscle of both morphotypes of the Mexican cavefish to determine citrate synthase (CS) activity as a measure of aerobic potential, and lactate concentration as a measure of anaerobic potential at three different chronic acclimation temperatures (14°C, 25°C, and 31°C). By examining aerobic and anaerobic potential in both morphs, we sought to link environmental thermal flexibility to muscle metabolism. We found that the surface morphotype had higher CS activity and lower lactate concentration, suggesting an overall more efficient usage of aerobic metabolism; whereas the cave morphotype showed lower CS activity and higher lactate concentration, suggesting a stronger reliance on anaerobic pathways. We also measured white muscle histological variables that have been previously linked to whole-animal metabolism: fiber diameter, number of nuclei per mm of fiber and myonuclear domain (MND) of both morphotypes at 25°C to examine cell-level differences in muscle morphology. However, we found no differences in fiber diameter, number of nuclei per mm of fiber or MND between the two morphotypes. Thus, although the cellular morphology is similar in these species, the environmental differences in the evolution of the two morphs has led to differences in their metabolic profiles.

PODSTAWOWA ANALIZA OKRYWY WŁOSOWEJ WIELBŁ ˛ADÓW W ZALEZNO ˙ SCI OD ICH PŁCI ´ I GATUNKU

The aim of this study was to analyze the diameter of hair fibers collected from camels kept in Poland, and to determine differences in fiber structure between camel sexes and species. Hair samples were collected for analysis from 28 adult camels divided into groups based on sex (18 females and 10 males) and species (18 dromedary camels and 10 Bactrian camels). The samples were collected in May–July 2020, at the level of the last rib. The diameter of 42,000 fibers was measured by the modified projection microscope method. The fibers were classified into three categories: non-medullated fibers, fibers with interrupted medulla and fibers with continuous medulla. The study demonstrated that the hair fibers of camels kept in Poland had a mean diameter of 20.23 µm. Non-medullated fibers had the smallest diameter (17.32 µm). The smallest significant (P ≤ 0.05) difference in fiber diameter between males and females was noted in non-medullated fibers. Mean fiber diameter was higher in males than in females, especially in guard hair. No differences in fiber medulla diameter were found between camel sexes or species. Hair from Bactrian camels was thinner, and the proportion of non-medullated fibers was more than 50% higher than in dromedaries.

Structural properties of optically clear bacterial cellulose produced by Komagataeibacter hansenii using arabitol.

Bacterial cellulose (BC) exhibits beneficial properties for use in biomedical applications but is limited by its lack of tunable transparency capabilities. To overcome this deficiency, a novel method to synthesize transparent BC materials using an alternative carbon source, namely arabitol, was developed. Characterization of the BC pellicles was performed for yield, transparency, surface morphology, and molecular assembly. Transparent BC was produced using mixtures of glucose and arabitol. Zero percent arabitol pellicles exhibited 25% light transmittance, which increased with increasing arabitol concentration through to 75% light transmittance. While transparency increased, overall BC yield was maintained indicating that the altered transparency may be induced on a micro-scale rather than a macro-scale. Significant differences in fiber diameter and the presence of aromatic signatures were observed. Overall, this research outlines methods for producing BC with tunable optical transparency, while also bringing new insight to insoluble components of exopolymers produced by Komagataeibacter hansenii.

Recessive mutation for low fibre curvature in the wool of sheep

Two mating experiments suggest a recessive gene for lustre in the birth coat of the lamb and low fibre curvature of the yearling fleece. Suffolk sheep normally have high wool fibre curvature, but a sire was found that had very low fibre curvature (21.0°/mm). In the first experiment, no lambs were born with a lustrous birth coat among the initial progeny from this sire (n = 32). Fleece samples at weaning (70.0°/mm) and yearling shearing (67.6°/mm) had high fibre curvature with no sign of segregation. All second-generation progeny of this sire (n = 4) were born with a lustrous birth coat, yet none survived to lamb shearing. Breeding was discontinued.In a second experiment, two male lambs were born with lustrous birth coats and low fibre curvature at weaning (29.0°/mm, 20.8°/mm). First generation progeny (n = 17, n = 18) from these sires showed no evidence of lustre of their birth coat, with fleece samples that were relatively high in fibre curvature at weaning (43.1°/mm, 43.8°/mm) and yearling (43.4°/mm, 45.4°/mm) respectively. When one sire was crossed back to the ewe progeny of both (n = 10) there was strong evidence for segregation of lustre of the birth coat. Lustrous lambs (n = 9) had low fibre curvature when shorn at weaning (21.0°/mm) in comparison with lambs (n = 8) with a wild-type birth coat (46.5°/mm) (P < 0.001). Fibre curvature had increased at yearling shearing of those recorded as lustrous at birth (41.6°/mm) but remained significantly lower (P = 0.001) than those that were recorded as wild-type (56.9°/mm). There was also a large difference in medullation between the two phenotypes, where the lustrous birth coat was associated with greater medullation in the fleece at weaning (54.5 %) and again as yearlings (22.5 %), compared with wild-type progeny (9.5 % and 4.0 %) respectively. There was no difference between birth coat types for weaning weight, yearling weight or fibre diameter variation at either age of fleece sampling. Fleece weight was considerably lower (P = 0.001) for yearlings that had lustrous birth coats (1.22 kg) than those with wild-type birth coats (1.76 kg), and though there was no significant difference in fibre diameter at this age, fleece samples taken at weaning were around 3 µm finer in wild-type lambs (P = 0.008). These results suggest a recessive gene for low fibre curvature was segregating in this population.

Identification of the key proteins associated with different hair types in sheep and goats.

Animal-derived fiber has the characteristics of being light, soft, strong, elastic and a good thermal insulator, and it is widely used in many industries and traditional products, so it plays an important role in the economy of some countries. Variations in phenotypes of wool fibers among different species and breeds are important for industry. We found that the mean fiber diameter of cashmere was significantly smaller than that of sheep wool (p < 0.01), and sheep wool was significantly smaller than goat wool (p < 0.01). Compared with traditional proteomics technology, we analyzed cashmere, guard hair, and wool by Laber-free proteomics technology and detected 159, 204, and 70 proteins, respectively. Through the sequential windowed acquisition of all theoretical fragmentations (SWATH), 41 and 54 differentially expressed proteins were successfully detected in the cashmere vs. wool group and guard hair vs. wool group. Protein‒protein interaction network analysis of differentially expressed proteins revealed many strong interactions related to KRT85, KRTAP15-1 and KRTAP3-1. The final analysis showed that the proportion of KRT85, KRTAP15-1 and KRTAP3-1 might be the key to the difference in fiber diameter and could be used as a potential molecular marker for distinguishing different fiber types.

Modeling Study on Oil Particle Filtration Performance of a Composite Coalescing Filter

The traditional theoretical model is not suitable for the simulation of the oil particle filtration process of a composite filter due to its huge difference in fiber diameter. In this paper, the concept of fiber dispersion σ was introduced into a mathematical model for describing the dynamic filtration process of a composite filter. The results show that the model is in good agreement with the experimental data. As the packing density is constant, the higher the fiber dispersion, the better performance is. In addition, the effect of different factors on the efficiency of different mechanisms was discussed. For fine particles (&amp;lt;0.1 μm), diffusion is the dominant mechanism. For coarse particles (&amp;gt;1 μm), the inertia impaction mechanism dominates the filtration efficiency. The fiber diameter has a significant effect on the inertia impaction mechanism. The single-fiber efficiency by inertia impaction mechanism is obviously affected by filtration velocity. The packing density has an effect on all mechanisms except for the diffusion mechanism. Moreover, such a model would contribute to an accurate prediction of the dynamic filtration performance of composite filters with polydisperse fiber diameter and improve performance by adjusting parameters reasonably.

Selection of Eucalyptus camaldulensis Families for Sustainable Pulpwood Production by Means of Anatomical Characteristics

Sustainable pulpwood production from fast-growing tree plantations is needed for pulp and paper industries. To increase the pulpwood production efficiency, the anatomical characteristics and derived-wood properties of 75 trees from 15 half-sib families of Eucalyptus camaldulensis Dehnh. planted in Thailand were investigated, and then the family was classified by suitability of wood as raw material for pulp and paper products using principal component analysis and clustering. The mean values of vessel diameter, vessel frequency, fibre diameter, fibre lumen diameter, and fibre wall thickness at 2 cm from the cambium were 128 µm, 16 no./mm2, 11.1 µm, 7.1 µm, and 1.88 µm, respectively. In addition, the Runkel ratio, Luce’s shape factor, flexibility coefficient, slenderness ratio, solids factor, and wall coverage ratio (i.e., derived-wood properties) were 0.53, 0.42, 0.64, 85.3, 68 × 103 µm3, and 0.34, respectively. Significant differences in fibre diameter, fibre lumen diameter, and Runkel ratio were found among families. Although significant differences among families were not found for other anatomical characteristics and derived-wood properties, the p-values obtained by an analysis of variance test ranged from 0.050 to 0.088. Based on the results of a principal component analysis and cluster analysis, 15 families were classified into four clusters with different expected pulp and paper characteristics. The suitability of wood from E. camaldulensis half-sib families for pulp and paper can be evaluated by principal component analysis using anatomical characteristics and physical properties as variables. Based on the results, desirable pulp and paper quality may be obtained through the selection of families from this species.

Type-2 muscle fiber atrophy is associated with sarcopenia in elderly men with hip fracture.

Sarcopenia is a common geriatric syndrome and can lead to falls and fragility fractures. It is associated with a decline of muscle fiber numbers and size. Muscle biopsies of the vastus lateralis muscle were taken from thirty-two patients with hip fracture (18 women and 14 men; mean age: 82.2±6.2years). Serial cross sections of skeletal muscle were labeled with myosin heavy chain slow (fiber type-1) and fast (fiber type-2) antibodies in order to measure the size, ratio and percentage of mixed fiber types. The presence of sarcopenia was defined according to the EWGSOP2 criteria by using BIA and handgrip strength measurement. Sarcopenia was identified in 5 patients (3 women and 2 men), probable-sarcopenia in 11 patients (4 women and 7 men). Significant differences in fiber diameter were found for fiber type-2 in men but not in women. Only 1-3% mixed fiber types were found in sarcopenic patients, indicating a final stage where reinnervation is not possible to occur anymore. Muscle fiber type-2 atrophy seems to be a histological marker for sarcopenia in men.

Effect of the local application of stem cells on repairing facial nerve defects: a systematic review

To systematically evaluate the repairing effect of stem cells on facial nerve defects. Articles regarding the regenerating effect of stem cells on facial nerves in animals were collected from the databases of Pubmed, Cochrane Library, Web of Science, Embase, Scopus, and CBM. Two professionals independently completed the article screening, data extraction, and bias risk assessment. RevMan 5.3 and random-effects models were used for the statistical analysis, and the results were presented in the form of mean differences (MD) with a 95%CI. The results of functional evaluation (vibrissae movement, facial paralysis) and histological evaluation (density of myelinated fibers, diameter of fibers, thickness of myelin sheath, G ratio) of facial nerve were Meta-analyzed. A total of 4 614 articles were retrieved from the 6 databases, and 15 of these articles were included in the Meta-analysis. For vibrissae movement and facial paralysis, the stem cell group scored significantly higher than the non-stem cell group (P<0.05). The density of myelinated fibers and thickness of the myelin sheath in the stem cell group were higher than those in the non-stem cell group (P<0.05). The G ratio in the stem cell group was smaller than that in the non-stem cell group (P=0.001). There was no significant difference in fiber diameter (P=0.08). Stem cells have potential in promoting facial nerve regeneration.

Seasonal muscle ultrastructure plasticity and resistance of muscle structural changes during temperature increases in resident black-capped chickadees (Poecile atricapillus) and rock pigeons (Columba livia)

Resident birds in temperate zones respond to seasonally fluctuating temperatures by adjusting their physiology, such as changes in basal metabolic rate or peak metabolic rate during cold exposure, or altering their organ sizes, so as to match the thermogenic requirements of their current environment. Climate change is predicted to cause increases in the frequency of heat and cold wave events, which could increase the likelihood that birds will face an environmental mismatch. Here, we examined seasonality and the effects of acute and chronic heat shock to 33°C and subsequent recovery from heat shock on the ultrastructure of the superficial pectoralis muscle fiber diameter, myonuclear domain (MND) and capillary density in two temperate bird species of differing body mass, the black-capped chickadee (Poecile atricapillus) and the rock pigeon (Columba livia). We found that muscle fiber ultrastructure did not change with heat treatment. However, in black-capped chickadees, there was a significant increase in fiber diameter in spring phenotype birds compared with summer phenotype birds. In rock pigeons, we saw no differences in fiber diameter across seasons. Capillary density did not change as a function of fiber diameter in black-capped chickadees, but did change seasonally, as did MND. Across seasons, as fiber diameter decreased, capillary density increased in the pectoralis muscle of rock pigeons. For both species in this study, we found that as fiber diameter increased, so did MND. Our findings imply that these two temperate birds employ different muscular growth strategies that may be metabolically beneficial to each.

Impact of setup orientation on blend electrospinning of poly-ε-caprolactone-gelatin scaffolds for vascular tissue engineering.

This article explores the effect of horizontal and vertical setups on blend electrospinning with two polymers having vastly different properties - poly-ε-caprolactone and gelatin, and subsequent effect of the resulting microstructure on viability of seeded cells. Poly-ε-caprolactone and gelatin of varying blend concentrations were electrospun in horizontal and vertical setup orientations. NIH 3T3 fibroblasts were seeded on these scaffolds to assess cell viability changes in accordance with change in microstructure. Blend electrospinning yielded a heterogeneous microstructure in the vertical orientation beyond a critical concentration of gelatin, and a homogeneous microstructure in the horizontal orientation. Unblended poly-ε-caprolactone electrospinning showed no significant difference in fibre diameter or pore size in either orientation. Mechanical testing showed reduced elasticity when poly-ε-caprolactone is blended with gelatin but an overall increase in tensile strength in the vertically spun samples. Cells on vertically spun samples showed significantly higher viabilities by day 7. The composite microstructure obtained in vertically spun poly-ε-caprolactone -gelatin blends has a positive effect on viability of seeded cells. Such scaffolds can be considered suitable candidates for cardiovascular tissue engineering where cell infiltration is crucial.

Histochemical study of rabbit medial pterygoid muscle during postnatal development.

The medial pterygoid muscle is a layered structure like the masseter muscle. This study aimed at investigating the regional differences in fiber type composition and fiber diameter of the medial pterygoid muscle in the rabbit from birth until 33weeks of age. Histochemical analysis of the medial pterygoid muscle was performed during five developmental stages (4, 9, 12, 18, and 33weeks after birth) in 30 male Japanese white rabbits. Six fiber types (I, IC, IIC, IIA, IIAB, and IIB) were identified by mATPase staining. An increase in diameter was observed in fiber types I and IC until 9weeks of age, and in fiber types IIC, IIA, IIAB, and IIB until 33weeks of age. No significant differences in fiber diameter were noted in the different regions of the pterygoid muscle. Moderate fast to slow fiber type shifts occurred from weeks 4-12; thereafter, a rapid slow to fast fiber type shift was observed. Significant differences in fiber type composition based on regional differences were noted at 4weeks of age. However, there was no difference in fiber type composition between regions at 33weeks. In conclusion, it was clear that the diameter and proportion of fast fibers had increased even after reaching sexual maturity in rabbits. In addition, the medial pterygoid muscle tissues appeared to be homogenous at 33weeks of age with very few differences between regions.

Physicomechanical and antibacterial properties of experimental resin‐based dental sealants modified with nylon‐6 and chitosan nanofibers

This study aimed to develop and evaluate resin-based experimental dental sealants containing electrospun nylon-6 (N6) and chitosan (CH) fibers in an attempt to improve the physicomechanical properties and provide an antibacterial protective effect, respectively. Electrospun N6 and CH mats were immersed into a resin mixture, light-cured, and then cryomilled to obtain micron-sized resin-modified fiber particles. Different levels of the novel cryomilled particles (i.e. 1, 2.5, and 5% relative to the resin mixture, % by weight) were used to prepare the N6- and CH-containing sealants. A commercial sealant and the experimental resin mixture (unfilled) were used as controls. Flexural strength (FS), Vickers microhardness (VH), and agar diffusion tests were performed. The data were analyzed at the 5% significance level. No significant difference in fiber diameter of N6 (503 ± 31 nm) and CH (595 ± 38 nm) was observed. Upon cryomilling, the resin-modified CH and N6 mats led to the formation of irregularly-shaped particles, with an average diameter of 14.24 µm and 15.87 µm, respectively. CH-5% had significantly higher FS (115.3 ± 1.3 MPa) than all the other groups. CH-1% had significantly higher hardness values (38.3 ± 0.3 VHN) than all the other groups. Collectively, the results indicated that CH-containing sealants presented the highest FS and hardness; however, none of the CH-containing sealants displayed antimicrobial properties.

Ultrafine wools: comfort and handle properties for next-to-skin knitwear and manufacturing performance

This study aimed to quantify the skin comfort and handle properties of a range of wool fabrics produced from ultrafine wool (13.7–15.1 µm) and in doing so determine if differences in fiber diameter and staple crimp frequency (5.3–7.1 crimps/cm) were important in these properties. The fabrics were evaluated using a range of subjective and objective measurement techniques, including the Wool ComfortMeter, the Wool HandleMeter and in wearer trials. This work indicated that single jersey fabrics made from ultrafine wool are approaching the limit of objective and subjective evaluation of next-to-skin comfort. The results from the Wool ComfortMeter, Wool HandleMeter and the wearer trial show that there were no significant effects that can be attributed to wool staple crimp (fiber curvature) in these ultrafine wool fabrics. The work also demonstrated a difference in the manufacturing response when knitted fabric made from wools of different fiber diameter (13.7–23.7 µm), and using yarns of the same count, resulted in a progressively higher fabric mass per unit area as mean fiber diameter was progressively reduced.

Clinical Classification of Cancer Cachexia: Phenotypic Correlates in Human Skeletal Muscle

BackgroundCachexia affects the majority of patients with advanced cancer and is associated with a reduction in treatment tolerance, response to therapy, and duration of survival. One impediment towards the effective treatment of cachexia is a validated classification system.Methods41 patients with resectable upper gastrointestinal (GI) or pancreatic cancer underwent characterisation for cachexia based on weight-loss (WL) and/or low muscularity (LM). Four diagnostic criteria were used >5%WL, >10%WL, LM, and LM+>2%WL. All patients underwent biopsy of the rectus muscle. Analysis included immunohistochemistry for fibre size and type, protein and nucleic acid concentration, Western blots for markers of autophagy, SMAD signalling, and inflammation.FindingsCompared with non-cachectic cancer patients, patients with LM or LM+>2%WL, mean muscle fibre diameter was reduced by about 25% (p = 0.02 and p = 0.001 respectively). No significant difference in fibre diameter was observed if patients had WL alone. Regardless of classification, there was no difference in fibre number or proportion of fibre type across all myosin heavy chain isoforms. Mean muscle protein content was reduced and the ratio of RNA/DNA decreased in patients with either >5%WL or LM+>2%WL. Compared with non-cachectic patients, SMAD3 protein levels were increased in patients with >5%WL (p = 0.022) and with >10%WL, beclin (p = 0.05) and ATG5 (p = 0.01) protein levels were increased. There were no differences in phospho-NFkB or phospho-STAT3 levels across any of the groups.ConclusionMuscle fibre size, biochemical composition and pathway phenotype can vary according to whether the diagnostic criteria for cachexia are based on weight loss alone, a measure of low muscularity alone or a combination of the two. For intervention trials where the primary end-point is a change in muscle mass or function, use of combined diagnostic criteria may allow identification of a more homogeneous patient cohort, reduce the sample size required and enhance the time scale within which trials can be conducted.

Electrospinning of ethyl cellulose fibres with glass and steel needle configurations

A novel device to produce ethyl cellulose fibres, an important biomaterial in modern food processing, using a glass needle in a modified electrospinning setup has been investigated. The effect of applied voltage on the fibre aspect ratio was analysed during electrospinning with a metallic (stainless steel) needle and then compared with that obtained with a glass–steel needle combination. A distinct difference in fibre diameter was observed between the two needle setups for the same processing conditions. A detailed quantitative study of the fibre length and diameter with respect to applied voltage was also carried out in order to determine any relationship between the needle material and the resulting electrospun fibres. There was an increase in fibre diameter in the case of steel–steel needle electrospinning with increasing applied voltage while a decrease in fibre diameter was observed with glass–steel needle electrospinning for the same voltage.

Diffusion Tensor Imaging of Skeletal Muscle - Correlation of Fractional Anisotropy to Muscle Power

Recent DTI studies demonstrated the possibility of fiber geometry visualization in skeletal muscle. We tested for an association between muscle power and standard DTI parameters, e. g. fractional anisotropy. Maximal muscle power (Lmax) of the soleus muscle was determined in 11 healthy subjects. Subsequently DTI was performed and standard parameters (fractional anisotropy - FA, mean diffusivity - MD, parallel diffusivity - PD, radial diffusivity - RD) were extracted in an ROI of the soleus muscle. We found a signficant association of Lmax with FA (neg. correlation: r = -0.85, p = 0.0015) and RD (pos. correlation r = 0.80, p = 0.047). There was no signficant association of MD or PD. Maximum muscle power is an indirect measure of fiber type distribution. The correlation between muscle power and DTI parameters can be explained by differences in fiber diameter and differences in the intracellular microstructure of type-1 and type-2 fibers. DTI should be evaluated as a tool for non-invasive quantification of fiber type distribution in skeletal muscle.

Genetic and phenotypic variation in five populations of Huacaya Alpacas (Vicugna pacos) from Peru

Five Peruvian alpaca populations from South Peru (San Juan de Tarucani, Estación Pillones and Chalhuanca from Arequipa Region and Palca and Lampa from Puno Region) were analysed at 20 microsatellite markers in order to estimate the genetic diversity. The association between the microsatellite genotypes and the fiber diameter traits was also examined in the alpacas of first shearing. A total of 230 alleles were observed from 272 DNA samples across the five populations. Gene diversity for each population ranged from 0.749 to 0.712 in Chalhuanca and Lampa populations respectively being the most diverse in the alpaca populations San Juan de Tarucani and Chalhuanca. The overall FIS value (0.15) was moderate and different from zero, the significant deficit of heterozygotes occurred in seven out of twenty surveyed loci within sampled alpacas. Considering the individual populations, the lowest heterozygote deficit was observed in Palca (0.123). The global FST value among the five alpaca populations were 0.02, San Juan de Tarucani and Palca were the least differentiated populations at the genetic level (0.012) and the highest level gene flow (Nm) of 19.66.The correspondence analysis, the genetic differentiation and the phylogenetic tree exhibited the same pattern of clustering, although the results of the phylogenetic relationships are not in accordance with the geographical location. This non-geographical sharing of the gene pools may be related to trading of male alpacas from the Lampa Province to the Chalhuanca and San Juan de Tarucani localities. The ANOVA showed that there were no significant differences in fiber diameter among the five populations with an overall mean of 18.96μm. The DUNCAN test showed in the total population the association between the fiber diameter and the alleles of the CVRL07, LGU68 and LCA65 microsatellite loci. Although to discard the spurious origin of this higher sample size relationship; number of microsatellite loci should be screened in further studies.