A novel orchiectomy surgical procedure in donkeys ( Equus asinus africanus) with parascrotal access.

Donkeys are a public health concern in the Northeast region of Brazil, with thousands of stray animals. Orchiectomy is an important population control measure; however, the long postoperative period with daily treatment of open wounds in the scrotum makes it difficult to perform a large number of castrations in sheltering centers. We evaluate a novel surgical procedure for orchiectomy in donkeys using parascrotal access. Twelve donkeys were used, divided into two groups: I - submitted to orchiectomy through parascrotal surgical access (novel procedure), and II - submitted to orchiectomy through scrotal access (conventional). Postoperative evaluations consisted of a macroscopic evaluation of the surgical wound (bleeding and intensity of edema), hematological parameters, and peritoneal fluid, which occurred in both groups at the moments (M): M0 - before the surgical procedure. The others moments occurred after surgery: M12 (twelve hours); M24 (twenty-four hours); M48 (forty-eight hours); M72 (seventy-two hours); M8D (eight days); and M16D (sixteen days). The surgical techniques did not generate an important systemic inflammatory response to the point detected by the leukogram, fibrinogen dosage, and peritoneal fluid. The parascrotal technique required long surgery but promoted less bleeding, less edema, and faster healing. The techniques used did not promote sufficient systemic inflammation to alter the number of leukocytes and the fibrinogen concentration; however, evaluation of the peritoneal fluid proved to be important for evaluating inflammatory processes involving the scrotum and inguinal canal. We describe a novel surgical procedure for orchiectomy in Donkeys using a parascrotal access that promoted less risk of bleeding, shorter period of edema, and healing time, but required longer surgery time.

Regulation of Escherichia coli SOS mutagenesis by dimeric intrinsically disordered umuD gene products.

Products of the umuD gene in Escherichia coli play key roles in coordinating the switch from accurate DNA repair to mutagenic translesion DNA synthesis (TLS) during the SOS response to DNA damage. Homodimeric UmuD(2) is up-regulated 10-fold immediately after damage, after which slow autocleavage removes the N-terminal 24 amino acids of each UmuD. The remaining fragment, UmuD'(2), is required for mutagenic TLS. The small proteins UmuD(2) and UmuD'(2) make a large number of specific protein-protein contacts, including three of the five known E. coli DNA polymerases, parts of the replication machinery, and RecA recombinase. We show that, despite forming stable homodimers, UmuD(2) and UmuD'(2) have circular dichroism (CD) spectra with almost no alpha-helix or beta-sheet signal at physiological concentrations in vitro. High protein concentrations, osmolytic crowding agents, and specific interactions with a partner protein can produce CD spectra that resemble the expected beta-sheet signature. A lack of secondary structure in vitro is characteristic of intrinsically disordered proteins (IDPs), many of which act as regulators. A stable homodimer that lacks significant secondary structure is unusual but not unprecedented. Furthermore, previous single-cysteine cross-linking studies of UmuD(2) and UmuD'(2) show that they have a nonrandom structure at physiologically relevant concentrations in vitro. Our results offer insights into structural characteristics of relatively poorly understood IDPs and provide a model for how the umuD gene products can regulate diverse aspects of the bacterial SOS response.

LexA repressor forms stable dimers in solution. The role of specific dna in tightening protein-protein interactions.

Cooperativity in the interactions among proteins subunits and DNA is crucial for DNA recognition. LexA repressor was originally thought to bind DNA as a monomer, with cooperativity leading to tighter binding of the second monomer. The main support for this model was a high value of the dissociation constant for the LexA dimer (micromolar range). Here we show that the protein is a dimer at nanomolar concentrations under different conditions. The reversible dissociation of LexA dimer was investigated by the effects of hydrostatic pressure or urea, using fluorescence emission and polarization to monitor the dissociation process. The dissociation constant lies in the picomolar range (lower than 20 pM). LexA monomers associate with an unusual large volume change (340 ml/mol), indicating the burial of a large surface area upon dimerization. Whereas nonspecific DNA has no stabilizing effect, specific DNA induces tightening of the dimer and a 750-fold decrease in the K(d). In contrast to the previous model, a tight dimer rather than a monomer is the functional repressor. Accordingly, the LexA dimer only loses its ability to recognize a specific DNA sequence by RecA-induced autoproteolysis. Our work provides insights into the linkage between protein-protein interactions, DNA recognition, and DNA repair.

The bioavailability and therapeutic effectiveness of prednisolone acetate vs. prednisolone sodium phosphate: a 20-year review.

The superior bioavailability and therapeutic effect of prednisolone acetate over prednisolone sodium phosphate was described about 15 years ago. Review of the original articles and subsequent studies show that in clinical situations the two medications are probably equally effective. Further, patient compliance studies show that prednisolone sodium phosphate may actually be superior.