Effect of physical, chemical and environmental characteristics on arbuscular mycorrhizal fungi in Brachiaria decumbens (Stapf) pastures

AIM

To evaluate the effects of soil physical and chemical factors (pH, conductivity, humidity, available phosphorus and organic matter) and environmental factors (temperature, relative air humidity, altitude and atmospheric pressure) on arbuscular mycorrhizal fungi (AMF)-Brachiaria decumbens grass relationship. Furthermore to establish patterns of microbiological responses that allow to differentiate the study sites in two relief types.

METHODS AND RESULTS

Mycorrhizal characteristics (spore density, external hyphae and root colonizations by hyphae, vesicles and arbuscules), physical and chemical factors in soil and environmental factors were measured.

CONCLUSIONS

The effect of physical, chemical and environmental factors on microbiological variables was related to the type of relief 'valley and hilly terrain'; the AMF behaviour was affected only over narrower ranges of evaluated variables. Similarly, the colonization of B. decumbens roots by AMF hyphae, vesicles and the mycorrhizal spore density follow different patterns according to the relief type.

SIGNIFICANCE AND IMPACT OF THE STUDY

The type of relief is one of the factors to be taken into consideration to evaluate the AMF inoculum and root colonization of these pastures, because of the influence of slope - as physical property of soil - on AMF.

Effects on testosterone, LH and cortisol concentrations, and on testicular ultrasonographic appearance of induced testicular degeneration in bulls

It is well known that heat stress has a detrimental effect on testicular functions. In addition to the alteration of semen quality and testicular damage, reproductive hormone secretion can be altered. The objective of this study was to describe changes in plasma concentrations of testosterone, LH and cortisol, as well as in testicular ultrasonographic appearance after induced testicular degeneration. Four Swedish Red and White bulls, aged 3 years, were used. They were fed according to Swedish standards. The scrotum was covered with an insulation device during 96 h. Semen was collected weekly 3 times before and up to 4 months after insulation. Testicular ultrasonography and clinical genital examination were performed with the same intervals. Heparinized blood samples were taken from the jugular vein at 2 h interval during 24 h every 2 weeks during the study. Blood samples were tested for the content of testosterone, LH and cortisol. Data were analysed, using one way analysis of variance of seminal data, clinical examination data as well as 24 h hormonal output data as percentage of mean individual pretreatment values. The use of a 5 MHz B-mode ultrasound unit did not contribute with an objective estimation of the degree of testicular degeneration. In 3 of the bulls testosterone levels had a tendency to decrease and LH to increase during the time of severe degeneration, whereas an opposite trend was seen during the regenerative phase, changes becoming significant 15 weeks after scrotal insulation. Variation between animals was big. Cortisol levels had a decreasing trend, changes being significant only in individual bulls at 10 and 15 weeks after scrotal insulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects on testosterone, LH and cortisol concentrations, and on testicular ultrasonographic appearance of induced testicular degeneration in bulls

It is well known that heat stress has a detrimental effect on testicular functions. In addition to the alteration of semen quality and testicular damage, reproductive hormone secretion can be altered. The objective of this study was to describe changes in plasma concentrations of testosterone, LH and cortisol, as well as in testicular ultrasonographic appearance after induced testicular degeneration. Four Swedish Red and White bulls, aged 3 years, were used. They were fed according to Swedish standards. The scrotum was covered with an insulation device during 96 h. Semen was collected weekly 3 times before and up to 4 months after insulation. Testicular ultrasonography and clinical genital examination were performed with the same intervals. Heparinized blood samples were taken from the jugular vein at 2 h interval during 24 h every 2 weeks during the study. Blood samples were tested for the content of testosterone, LH and cortisol. Data were analysed, using one way analysis of variance of seminal data, clinical examination data as well as 24 h hormonal output data as percentage of mean individual pretreatment values. The use of a 5 MHz B-mode ultrasound unit did not contribute with an objective estimation of the degree of testicular degeneration. In 3 of the bulls testosterone levels had a tendency to decrease and LH to increase during the time of severe degeneration, whereas an opposite trend was seen during the regenerative phase, changes becoming significant 15 weeks after scrotal insulation. Variation between animals was big. Cortisol levels had a decreasing trend, changes being significant only in individual bulls at 10 and 15 weeks after scrotal insulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase I trial of aclacinomycin-A. A clinical and pharmacokinetic study

Aclacinomycin-A is a new anthracycline antibiotic with a broad spectrum of antitumor activity in animals. Compared to doxorubicin, it was found to produce less cardiotoxicity and alopecia. A Phase I trial of aclacinomycin-A given as a weekly 15 min IV infusion was conducted in 20 previously treated patients with advanced solid tumors. Four dose levels ranging from 40 to 100 mg/m2 were studied; myelotoxicity was dose-limiting at 85 and 100 mg/m2. Other toxicities were moderate to severe nausea and vomiting in 9 patients, mild phlebitis in 2 patients, and mild abnormality of liver function tests in 3 patients. No cardiac or renal toxicities were seen, but two partial responses were observed. The pharmacokinetic profile of aclacinomycin-A in plasma and urine was studied in 3 patients given 65 mg/m2 using a high performance liquid chromatography assay. The data obtained were consistent with a two compartment model of drug disposition with initial and terminal half-life values of 6.6 min and 13.3 h, respectively. The major fluorescent metabolite was eliminated with a terminal half-life of 25 h. Two metabolites as well as the parent drug were excreted in the urine as less than 10% of the doses given. This pharmacokinetic profile is similar to that of other anthracyclines, although aclacinomycin-A appears to have lower blood levels than doxorubicin given at equivalent doses. On this weekly schedule, the recommended dose is 65 mg/m2 for Phase II trials.