A dose-finding,long-term study on the use of calcium chloride in saline solution as a method of nonsurgical sterilization in dogs: evaluation of the most effective concentration with the lowest risk

Background

Canine overpopulation is a global issue with serious health and welfare implications. Nonsurgical methods of sterilization could yield positive impacts on this problem, but no long-term data on such methods are available. The objective of the current investigation was to determine the effects of intratesticular injections of calcium chloride dihydrate (CaCl₂) in saline in dogs over a one year period. Five concentrations (0%, 10%, 20%, 30%, 60%) of CaCl₂ in saline were administered via intratesticular injection to groups of 10 dogs each. Total sperm count and motility, blood levels of testosterone, and side effects were examined at 0, 2, 6, and 12 months post-injection (PI). Testicular size and semen volume were examined at 0 and 12 months PI.

Results

Total sperm count, semen volume and testosterone showed significant dose-dependent decreases upon treatment with 10%-60% CaCl₂ compared with either the control group (0% CaCl₂) or baseline for each treatment group. Azoospermia was achieved for at least 12 months PI in 60% and 80% of treated dogs after administration of a 10% and 20% CaCl₂, respectively. Treatment with 30% or 60% CaCl₂ resulted in azoospermia in 100% of dogs, but more side effects were observed, while no side effects were noticed at lower doses. For each treatment group, testosterone levels had decreased an average of 35%-70% at 6 months following treatment. However, testosterone levels rebounded by the 12-month time point in all groups except the highest dosage group (60% CaCl₂), which remained at the low end of physiological range throughout the study. Sperm motility dropped to zero or near zero in all dogs treated with CaCl₂. Testicular size was significantly smaller at 12 months PI for all groups when compared to baseline.

Conclusions

This first long-term study confirms reports of the efficacy of CaCl₂ sterilization. However, at dosages free of adverse events, calcium chloride in saline may not provide permanent sterilization as previously believed. Future work should explore optimized solvents to increase the permanence of the well-tolerated 20% formulation.     

Giant Piezoelectric Effect in Strontium Titanate at Cryogenic Temperatures

Piezoelectric materials have many applications at cryogenic temperatures. However, the piezoelectric response below 10 kelvin is diminished, making the use of these materials somewhat marginal. Results are presented on strontium titanate (SrTiO3), which exhibits a rapidly increasing piezoelectric response with decreasing temperature below 50 kelvin; the magnitude of its response around 1 kelvin is comparable to that of the best materials at room temperature. This "giant" piezoelectric response may open the way for a broad class of applications including use in ultralow-temperature scanning microscopies and in a magnetic field-insensitive thermometer. These observations, and the possible divergence of the mechanical response to electric fields at even lower temperatures, may arise from an apparent quantum critical point at absolute zero.     

泸州荔枝果园AM真菌菌根及孢子数量调查与分析

[目的]对泸州荔枝园AM真菌进行调查,确认荔枝菌根类型,了解果园土壤中AM真菌孢子种群数量的大致情况。[方法]利用"湿筛法"和Phllips&Hayman的方法对3个泸州荔枝果园春季的土壤AM真菌进行了调查分析。[结果]荔枝菌根是内生菌根,共生真菌为囊泡——丛枝菌根真菌,即AM真菌。春季的菌根感染率在9%~32%之间,普遍低于25%。VA菌根感染率的平均值在15%~21%之间,低于25%。三个荔枝园每25 g土样中AM真菌孢子数平均值为869±76个。[结论]果园生草或对果园进行有机覆盖,是促进荔枝生长,增加荔枝果实产量,改善荔枝果实品质的一种绿色环保途径。     

Local Control of Microdomain Orientation in Diblock Copolymer Thin Films with Electric Fields

Local control of the domain orientation in diblock copolymer thin films can be obtained by the application of electric fields on micrometer-length scales. Thin films of an asymmetric polystyrene-polymethylmethacrylate diblock copolymer, with cylindrical polymethylmethacrylate microdomains, were spin-coated onto substrates previously patterned with planar electrodes. The substrates, 100-nanometer-thick silicon nitride membranes, allow direct observation of the electrodes and the copolymer domain structure by transmission electron microscopy. The cylinders aligned parallel to the electric field lines for fields exceeding 30 kilovolts per centimeter, after annealing at 250°C in an inert atmosphere for 24 hours. This technique could find application in nanostructure fabrication.     

Isotopic evidence for neogene hominid paleoenvironments in the kenya rift valley

Bipedality, the definitive characteristic of the earliest hominids, has been regarded as an adaptive response to a transition from forested to more-open habitats in East Africa sometime between 12 million and 5 million years ago. Analyses of the stable carbon isotopic composition (delta(13)C) of paleosol carbonate and organic matter from the Tugen Hills succession in Kenya indicate that a heterogeneous environment with a mix of C3 and C4 plants has persisted for the last 15.5 million years. Open grasslands at no time dominated this portion of the rift valley. The observed delta(13)C values offer no evidence for a shift from more-closed C3 environments to C4 grassland habitats. If hominids evolved in East Africa during the Late Miocene, they did so in an ecologically diverse setting.     

Effects of different irrigation regimes on a super-high-density olive grove cv. “Arbequina”: vegetative growth,productivity and polyphenol content of the oil

The effects of multiple irrigation regimes on the relationships among tree water status, vegetative growth and productivity within a super-high-density (SHD) “Arbequina” olive grove (1950 tree/ha) were studied for three seasons (2008–2010). Five different irrigation levels calculated as percentage of crop irrigation requirement using FAO procedures (Allen et al. in Crop evapotranspiration. Guidelines for computing crop water requirements. Irrigation and drainage paper 56. FAO, Rome, 1998) were imposed during the growing season. Periodically during the growing season, daytime stem water potential (Ψ _STEM), inflorescences per branch, fruits per inflorescence and shoot absolute growth rate were measured. Crop yield, fruit average fresh weight and oil polyphenol content were measured after harvest. The midday Ψ _STEM ranged from ?7 to ?1.5 MPa and correlated well enough with yield efficiency, crop density and fruit fresh weight to demonstrate its utility as a precise method for determining water status in SHD olive orchards. The relationships between midday Ψ _STEM and the horticultural parameters suggest maintaining Ψ _STEM values between ?3.5 and ?2.5 MPa is optimal for moderate annual yields of good quality oil. Values below ?3.5 MPa reduced current season productivity, while values over ?2.5 MPa were less effective in increasing productivity, reduced oil quality and produced excessive crop set that strongly affected vegetative growth and fruit production the following season. On the basis of the result given here, irrigation scheduling in the new SHD orchards should be planned on a 2-year basis and corrected annually based on crop load. Collectively, these results suggest that deficit irrigation management is a viable strategy for SHD olive orchards.     

Effects of adding polyclonal antibody preparations on ruminal fermentation patterns and digestibility of cows fed different energy sources

Nine ruminally cannulated cows fed different energy sources were used to evaluate an avian-derived polyclonal antibody preparation (PAP-MV) against the specific ruminal bacteria Streptococcus bovis, Fusobacterium necrophorum, Clostridium aminophilum, Peptostreptococcus anaerobius, and Clostridium sticklandii and monensin (MON) on ruminal fermentation patterns and in vivo digestibility. The experimental design was three 3 × 3 Latin squares distinguished by the main energy source in the diet [dry-ground corn grain (CG), high-moisture corn silage (HMCS), or citrus pulp (CiPu)]. Inside each Latin square, animals received one of the feed additives per period [none (CON), MON, or PAP-MV]. Dry matter intake and ruminal fermentation variables such as pH, total short-chain fatty acids (tSCFA), which included acetate, propionate, and butyrate, as well as lactic acid and NH(3)-N concentration were analyzed in this trial. Total tract DM apparent digestibility and its fractions were estimated using chromic oxide as an external marker. Each experimental period lasted 21 d. Ruminal fluid sampling was carried out on the last day of the period at 0, 2, 4, 6, 8, 10, and 12 h after the morning meal. Ruminal pH was higher (P = 0.006) 4 h postfeeding in MON and PAP-MV groups when compared with CON. Acetate:propionate ratio was greater in PAP-MV compared with MON across sampling times. Polyclonal antibodies did not alter (P > 0.05) tSCFA, molar proportion of acetate and butyrate, or lactic acid and NH(3)-N concentration. Ruminal pH was higher (P = 0.01), 4 h postfeeding in CiPu diets compared with CG and HMCS. There was no interaction between feed additive and energy source (P > 0.05) for any of the digestibility coefficients analyzed. Starch digestibility was less (P = 0.008) in PAP-MV when compared with CON and MON. In relation to energy sources, NDF digestibility was greater (P = 0.007) in CG and CiPu vs. the HMCS diet. The digestibility of ADF was greater (P = 0.002) in CiPu diets followed by CG and HMCS. Feeding PAP-MV or monensin altered ruminal fermentation patterns and digestive function in cows; however, those changes were independent of the main energy source of the diet.     

Testicular Volume and Daily Sperm Output in Ragusano Donkeys

A careful evaluation of daily sperm output (DSO) and seminal parameters is indicative of the potential fertility of the animal and at the same time is useful for maximization of the reproductive activity. The aim of this article was to evaluate the seminal parameters, testicular volume (TV) calculated by ultrasound measurements, DSO, and any eventual relationship between these in Ragusano donkey jackasses. Eight Ragusano donkey stallions underwent a morphometric evaluation of the testes by ultrasound to calculate the TV, and daily semen collection for 10 consecutive days. TV ranged from 250 to 500 cm³ and no significant differences could be observed between the left and right testes. Only ejaculates from 4 to 10 days were analyzed, given that there was evidence that the sperm extragonadal reserve interfered with the total number of sperm in ejaculates during the early days. DSO in the Ragusano donkey ranged from 7 to 23 × 10⁹ sperms. The seminal parameters showed high values of motility, viability, and low abnormality percentages. Age, TVs, and sperm parameters were not significantly correlated. The correlation between TV and DSO was poor (P = .1) in this study and this may suggest that TV and DSO might simply not be highly correlated in the donkey.     

Last occurrence and survival during winter of the arbovirus vector Culicoides brevitarsis at the southern limits of its distribution

SUMMARY: Linear regression analysis was used to describe the decline in numbers of Culicoides brevitarsis Kieffer into winter with monthly maximum, average and minimum temperatures at the southern limits to its distribution in New South Wales. From this, low temperature thresholds were derived when C brevitarsis would be absent from the field. The low minimum threshold ± 2 SE (95% Confidence Interval) of 8.1 ± 0.3°C was used with historical temperature data to estimate the last month that the species should occur (March to June) and the mean number of months (2 to 6.5) below the threshold at 17 selected sites. Probability for survival during winter at these sites was estimated from years when the number of consecutive months below the threshold was ≤ 2 months. This varied from zero to 51% depending on the location of the site. Last occurrence was 0.7 months later on average and absolute probabilities for survival ranged from zero to 100% when the temperatures were increased by an arbitrary 2°C.