Chicken histone H4 labeled at Met-84 with the fluor N-[(acetylamino)ethyl]-8-naphthyl-amine-1-sulfonic acid has been incorporated into a nucleosome which has physical characteristics virtually identical with those of native core nucleosomes. The fluorescence emission and polarization properties of the labeled nucleosome were measured as a function of ionic strength and the binding of high mobility group (HMG) proteins 14 and 17. Also, the accessibility of the fluor to the quenching agent acrylamide was determined. It was found that the fluorescence emission changes in the range 0.1-1000 mM NaCl are rather small and indicate that no major unfolding of the octamer structure occurs around Met-84 on H4 at least. Five or perhaps six discrete states were found in that ionic strength range. Each has a different accessibility to the quenching agent. The range of accessibilities varied from 9 X 10(-7) to 32 X 10(-7) mol-1 s-1 for 0.1-1000 mM NaCl, respectively. Polarization measurements showed that there was little change in the rotational relaxation lifetime of the fluor at ionic strengths less than 50 mM NaCl. Above this value, the rotational relaxation lifetimes decreased from 107 to 25 ns at 600 mM NaCl, indicating a moderately increased rotational freedom for the fluor. It is suggested that the histone octamer changes its degree of compaction in the range 0.1-600 mM NaCl but that no major protein unfolding occurs.(ABSTRACT TRUNCATED AT 250 WORDS)

Leptospira spp., a zoonotic agent relevant for public health, occurs frequently in tropical regions. The aquatic environment represents a viable survival and transmission pathway. This study aimed to investigate the presence of anti-Leptospira spp. antibodies in Phrynops geoffroanus (Geoffroy's side-necked turtle) serum samples using the microagglutination test (MAT), and Leptospira spp. in gastric and cloacal lavage samples using the polymerase chain reaction (PCR) technique. Antibodies against nine different Leptospira spp. serovars were detected in 45.45% (30/66) of the serum samples. Specific amplification of Leptospira spp. genomic material (331bp) was observed in 16.67% (11/66) of the samples. In conclusion, these freshwater testudines host Leptospira spp. and eliminate them. This situation may represent a risk to public health, especially to people who use urban streams for fishing and recreational activities. Additionally, we described some Leptospira spp. serovars, not yet reported in testudines, detected here in P. geoffroanus.

ABSTRACT:The purpose of the current study was to develop a new tibial tuberosity advancement (TTA) technique, by replacing the original titanium cage with a Ricinus communis polyurethane resin-made wedge polymer. The implants were manufactured using the same size and angles of the original titanium cages, though larger distally. The modified TTA technique (TTAm) was performed in 42 knees of 35 dogs diagnosed with rupture of the cranial cruciate ligament (RCCL). Animals were submitted to radiographic and gait assessments preoperatively, early postoperatively and following 30, 60, 90 and 120 days. All animals exhibited good clinical outcome. There were no cases of impaired healing or bone resorption until 120 days postoperatively and there was no patient with patellar distress after TTAm. Scores of gait evaluation revealed differences between time points. There were also differences between the evaluations of control and pre-and post-operative times. However, there was no difference among the assessment of 30 days and the following time points. The use of the polyurethane polymer for TTAm was advantageous, not only due to biocompatibility and osseointegration, but also for providing easy handling; it can be moulded intra-operatively if necessary. Moreover, it allows precise adaptation to the osteotomy site, as opposed to the original TTA metallic implants, which cannot be moulded. It is suggested that incision lengths for TTAm are slightly shorter than those required for the conventional TTA as this requires the distal fixation of the plate at the beginning of the middle third of the body of the tibia. The TTAm does not require the use of fixation plates and it is performed only at the cranial aspect of the tibia. The method of attachment of the tibial tuberosity in the craniocaudal direction was effective. The setting associated with the use of the polyurethane polymer allowed simplification of the technique for easier implementation, and the amount of implant material required to perform TTAm was reduced in comparison to the conventional TTA. This technique can be used for treating the knees of dogs with RCCL, and provides for easy execution, less invasiveness to the tissues of the knee joint and more versatility in comparison to conventional TTA.

The purpose of study was to assess long-term clinical and radiographic aspects of dogs’ stifle joints which had undergone a modified tibial tuberosity advancement technique (mTTA). A total of 15 stifles that had undergone mTTA for CCL disease of 11 patients were included in this study. Assessments involved patient’s gait analysis, cranial drawer and tibial compression tests, stifle goniometry range of articular motion, thigh and leg girth and radiographic evidence of progression of osteoarthrosis. Variables were compared between operated and healthy limbs and among moments (M0) on the early postop; (M1) 120 days postop; and (M2) approximately 5 years following surgery. A questionnaire regarding owner’s perceptions after approximately 5 years of surgery was assessed. Most dogs presented positive response to cranial drawer and tibial compression tests on operated knees. There was also decrease on goniometry and thigh girth and increase in leg girth. Radiographic evidence of progression of osteoarthritis was seen especially on the long-term follow-up (M2). On gait analysis, most animals presented some degree of lameness in different conditions, in contrast to owners’ perceptions. Osteoarthritis still develops in dogs following mTTA surgery for CCL disease. However, owners were overall satisfied with their recovery and would be willing to accept indication of mTTA for dogs with ruptured CCL.

Chicken histone H4, labeled at methionine-84 with 1-N-pyrenyliodoacetamide, has been incorporated into a nucleosome-like particle with core length DNA and unmodified histones H2A, H2B, and H3. These synthetic nucleosomes exhibit properties very similar to those displayed by native particles and those labeled with other fluors. The emission spectrum of the pyrene-labeled nucleosome was characteristic of excited dimer (excimer) fluorescence, indicating that the single pyrene groups on the two H4 molecules are in close proximity in the reconstituted particle. Histone H4 was also labeled randomly at lysines with a group that contains two pyrene moieties separated by 12 A at most. Incorporation of this histone into nucleosome-like particles provides an excimer standard which does not depend on intermolecular interactions. The properties of the pyrene-containing nucleosome were examined as a function of ionic strength. It was found that the H4-H4 pyrene excimer fluorescence exhibited a cooperative disruption centered at 0.1 M NaCl which preceded increases in accessibility and environment polarity revealed by other fluors attached at the same site.