Odd-valent nickel-catalyzed intermolecular carboiodination of alkynes with aryl iodides to form highly substituted and functionalized alkenyl iodides has been developed.

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ABSTRACT. The peripheral blood plasma testosterone (T) levels and superoxide dismutase (SOD) activity were measured in 5 azoospermic (AZ-) beagles. The mean values in the AZ-dogs were significantly lower than in 7 control beagles (P<0.001). Subcutaneous injections of 1 µg/kg GnRH analogue three times weekly in the AZ-dogs induced significant increases in mean T level and SOD activity (P<0.05) and improvement in spermatogenesis. Thus, spermatogenic function in the dog appears to be maintained by T and normal SOD activity in the testis. KEY WORDS: azoospermia, canine, SOD.J. Vet. Med. Sci. 69(5): 561-562, 2007 Production of reactive oxygen species (ROS) by testicular tissue [13,18] and sperm [1,17] has been reported in male animals. Oxidative stress caused by elevated ROS concentrations induces spermatogenic dysfunction [9] and poor semen quality [10], and high ROS concentrations in the seminal plasma of dogs also causes low sperm motility [15]. Superoxide dismutase (SOD) is known to be the most important antioxidant enzyme in seminal plasma [5], and SOD activity has been detected in canine seminal plasma [2]. Leydig [8] and Sertoli cells [11] have been reported to produce SOD in the testis. Low SOD activity in seminal plasma causes infertility in humans [14]. Although the cause of spermatogenic arrest in the dog is not well understood [4], the authors have reported that GnRH analogue (-A) injection transiently improved the semen quality of some dogs with poor testosterone (T) secretory function in the testes and spermatogenic dysfunction [7]. In the present study the plasma T levels and testicular SOD activities of azoospermic (AZ-) dogs were measured after GnRH-A injections in order to investigate the cause of spermatogenic dysfunction and the interaction between T secretory function and SOD activity in the testes.Five AZ-beagles (4-7 years old) cared for at our university were used in this study. The 5 dogs had previously been diagnosed with azoospermia based on examinations of ejaculated semen collected by digital manipulation at weekly intervals for 4 weeks. Seven beagles (3-6 years old) with normal semen quality (the total number of sperm was more than 300 × 10 6 , more than 80% of sperm were actively motile, and less than 10% of sperm were abnormal) were used as controls.The GnRH-A used in this study was GnRH ethylamide (D-Ser-(tBu)-des-gly-NH 2 ; Buserelin, Hoechst Inc., Germany). The AZ-dogs were given 3 weekly subcutaneous injections of 1 µg GnRH-A per kilogram body weight according to the method described previously [7]. Blood samples were collected from a peripheral vein 5 weeks before and 10 weeks after the first injection of GnRH-A. Since the plasma T level of male dogs fluctuates diurnally [6,16], blood samples were collected 3 times a day (09:00, 13:00, 17:00). Plasma T levels were determined by radioimmunoassay using the method described by DePalatis et al. [3], and the mean T level was calculated for the 3 plasma samples collected each day.Tissue was collected twice from the right testis of ...

A cobalt porphyrin efficiently catalyzed the formal [3+2] cycloaddition of alkyl-/aryl-substituted cyclopropanes and carbonyl compounds such as aldehydes and ketones to afford the corresponding substituted tetrahydrofurans. The use of the cobalt porphyrin complex as a Lewis acid to catalyze the reaction via the electrophilic activation of cyclopropanes was demonstrated. The high functional-group tolerance and robustness of the catalyst were also demonstrated. Further, the potential utility of the catalyst was demonstrated by performing the cycloaddition of cyclic ketones and cyclopropanes to afford spiro tetrahydrofurans.