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REASONS FOR PERFORMING STUDY: The effectiveness and best method to manage dorsal cortical stress fractures is not clear. This study was performed to evaluate the success of lag screw fixation of such fractures in a population of Thoroughbred racehorses. HYPOTHESIS: Lag screw fixation of dorsal cortical stress fractures is an effective surgical procedure allowing racehorses to return to their preoperative level of performance. METHODS: The records of 116 racehorses (103 Thoroughbreds) admitted to Equine Medical Centre, California between 1986 and 2008 were assessed. Information obtained from medical records included subject details, limb(s) affected, fracture configuration, length of screw used in repair and presence of concurrent surgical procedures performed. Racing performance was evaluated relative to these factors using Fisher's exact test and nonparametric methods with a level of significance of P<0.05. RESULTS: Of 92 Thoroughbred horses, 83% raced preoperatively and 83% raced post operatively, with 63% having ≥5 starts. There was no statistically significant association between age, gender, limb affected, fracture configuration or presence of concurrent surgery and likelihood of racing post operatively or of having 5 or more starts. The mean earnings per start and the performance index for the 3 races following surgery were lower compared to the 3 races prior to surgery; however, 29 and 45% of horses either improved or did not change their earnings per start and performance index, respectively. CONCLUSIONS AND POTENTIAL RELEVANCE: Data show that lag screw fixation is successful at restoring ability to race in horses suffering from dorsal cortical stress fractures.

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OBJECTIVE: To compare the pharmacology, in vitro activity, and clinical use of the new macrolide antibiotics, azithromycin and clarithromycin, in the treatment of infections caused by mycobacteria other than Mycobacterium tuberculosis. DATA IDENTIFICATION: An English-language literature search using MEDLINE (1987-1994), Index Medicus (1987-1994), Program and abstracts of the 31st (1991) and 32nd (1992) Interscience Conference on Antimicrobial Agents and Chemotherapy, and bibliographic reviews of related textbooks, review articles, and professional society publications. STUDY SELECTION: 105 articles were selected. In vitro and in vivo reports on the pharmacokinetics, microbiology, pharmacology, and effectiveness of clarithromycin and azithromycin were assessed to compare their effectiveness and safety. Emphasis was placed on the use of these new drugs in treating infections caused by Mycobacterium avium complex, Mycobacterium chelonae, and Mycobacterium fortuitum infections. RESULTS: A review of the in vitro activity of the new macrolides revealed moderate to very good activity against many strains of mycobacteria other than M. tuberculosis. Early clinical trials show promising results in pulmonary infections, lymphadenitis, cutaneous infections, and disseminated infections. CONCLUSIONS: The new macrolides, azithromycin and clarithromycin, show great promise for treating infections caused by these acid-fast bacteria. Clarithromycin is recommended as a component of combination therapy for the treatment of M. avium complex infections in patients with AIDS. The development of resistance in patients, particularly when these agents are used alone, has been reported.

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We describe the second reported case of peritonitis caused by the fungus Exophiala jeanselmei in a patient on continuous ambulatory peritoneal dialysis (CAPD) and the first such patient to survive. Management of the patient consisted of Tenckhoff catheter removal and intravenous amphotericin B.

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Lameness problems constitute a major part of racing Quarter Horse practice. This article considers the diagnosis, prognosis, and treatment of the frequently encountered lamenesses. The main conditions included are synovitis, intra-articular fractures, osteochondritis dissecans, and degenerative joint disease as they relate to the coffin, fetlock, carpal, and tarsal joints. Intra-articular injection techniques and medications are discussed because of the frequency of joint disease. Bucked shins and stress fractures are also reviewed.

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The various conditions of the interphalangeal joint are presented; these include degenerative joint disease and osteochondral chip fractures of the proximal interphalangeal joint, fractures of the middle phalanx affecting proximal and/or distal interphalangeal joints, subluxation and osteochondrosis of the proximal interphalangeal joint, and arthrosis of the distal interphalangeal joint.

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The effects of the administration of serotonergic drugs on infusion rates of rats self-administering cocaine and amphetamine on an FR-10 schedule of reinforcement in daily 4 hour sessions were compared. Pretreatment with fluoxetine (2.5, 5, and 10 mg/kg), an inhibitor of serotonin reuptake, significantly decreased rates of responding maintained by amphetamine, but had no effect on responding maintained by cocaine at any of the doses tested. Pretreatment with cinanserin (3, 10, and 17.5 mg/kg), a serotonergic receptor antagonist, decreased rates of amphetamine self-administration at the highest dose tested, and also had no effect on cocaine self-administration. These data suggest a differential sensitivity of cocaine and amphetamine self-administration to pharmacological manipulation of central serotonin systems. They are consistent with biochemical data which demonstrates a negative correlation between the reinforcing potency of amphetamine-like drugs, but not cocaine-like drugs and their potency at serotonin binding sites.

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The reinforcing properties of amfonelic acid, a nonamphetamine psychostimulant, were evaluated in an intravenous self-administration paradigm. Rats were trained to self-administer cocaine (0.5-3.0 mg/kg/infusion) on a fixed-ratio 10 schedule of reinforcement via surgically implanted intravenous catheters during daily 4-hr sessions. Substitution of amfonelic acid (0.0625-0.250 mg/kg/infusion) reliably maintained self-administration in a dose-dependent manner. These data indicate that amfonelic acid can act as a reinforcer in rats, and further suggest that amfonelic acid may have abuse potential in humans.

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Antigens derived from three different yeast strains of Histoplasma capsulatum (GW and VC used by the Veterans Administration Serology Reference Laboratory and the Centers for Disease Control reference antigen, A811) were compared with each other to determine their equivalency. Results from 200 sera, tested concurrently by the Serology Reference Laboratory and the University of Kentucky Mycoserology Laboratory, indicated that the VC yeast antigen gave better correlation to the A811 antigen than did the GW antigen.

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The p-nitro-alpha-acetylamino-beta-hydroxypropiophenone (NAP) differential test for the identification of Mycobacterium tuberculosis recovered from clinical specimens was evaluated by two laboratories and found to be a rapid and accurate procedure with a specificity exceeding 99%.

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Four hundred forty-one clinical isolates of the family Enterobacteriaceae were identified in parallel by using the API Rapid E 4-h and the API 20E overnight procedures (Analytab Products, Plainview, N.Y.). The results obtained by using the API Rapid E were compared with those obtained by using the API 20E. Discrepancies were resolved by using standard biochemicals. The API 20E identified 98.9% (436 of 441) of the isolates without the use of additional biochemicals and was found to be correct in each case of a discrepancy among the 436 isolates. The API Rapid E gave the same identification as the API 20E for 94.0% (410 of 436) of the isolates, misidentified 3.0% (13 of 436), and gave a correct but low-selectivity answer for the remaining 3.0% (13 of 436). The API Rapid E is a suitable alternative for the rapid identification of the Enterobacteriaceae.

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It is concluded that the validly published genera Candida and Torulopsis are taxonomically distinct. The recently proposed merger of these two yeast genera is rejected.

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The pathogenicity of the purified basidiospores of Filosbasidiella neoformans was determined. The basidiospores were purified by successive filtration and inoculated into white Swiss female mice via the intracranial and intravenous route. At autopsy, infection was seen with as few as fifty inoculated cells. The brain, liver and spleen were examined culturally and histologically to prove the pathogenicity of the purified basidiospores .

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A total of 463 respiratory specimens, all smear positive for acid-fast bacteria, were inoculated onto routine solid media and into BACTEC 7H12 Middlebrook medium for detection of mycobacterial growth. Conventional drug susceptibility testing (1% proportion method) was performed on Middlebrook 7H10/7H11 medium, and radiometric susceptibility testing was performed on BACTEC 7H12 medium. The average detection times for BACTEC-positive cultures were 8.3 days for Mycobacterium tuberculosis and 5.2 days for mycobacteria other than tuberculosis; by conventional methods, they were 19.4 and 17.8 days, respectively. These detection times do not include time required for identification, which was done by the conventional method only. There was an excellent correlation in the recovery rates of mycobacteria by the two methods. Drug susceptibility test results of M. tuberculosis isolates by the two methods showed 95.1 to 100% overall agreement. The average reporting time for drug susceptibility results ranged from 4.2 to 6.9 days for the BACTEC method and 13.7 to 21 days for the conventional methods. An average of 18 days was required by the BACTEC method for complete recovery and drug susceptibility testing of M. tuberculosis, as compared with 38.5 days for the conventional methods.

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Cryptococcus neoformans is a yeast-like organism which, after inhalation, may cause pulmonary disease or a systemic fungemia associated with numerous extrapulmonary sites of infection, but most notably affecting the central nervous system. Despite this frequent involvement of the leptomeninges, only three cases of infection of the temporal bones have been previously described. We describe an additional case with comments on the possible significance of infection of this site.

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The pathogenicity of the purified hyphae of Filobasidiella neoformans was determined. The hyphal particles were inoculated into white Swiss female mice via the intracranial and intravenous route. Upon autopsy, infection was seen with as few as 25 hyphal elements. The brain, liver, and spleen were examined culturally and the brain examined histologically to prove the pathogenicity of the purified hyphae.

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A retrospective study of 34,314 sputum specimens received by a reference laboratory over a 10-year period demonstrated that clinically significant fungi could be isolated even after long periods of delay between collecting and culturing. As a result of this study, it should be stressed that although immediate culturing for fungi is the ideal, specimens should not be rejected because of delays in transport.

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Interactions between macrophages (alveolar and peritoneal) from normal, vaccinated (with heat-killed yeast cells), and Mycobacterium bovis BCG-treated mice and the mycelial and yeast phases of Histoplasma capsulatum were observed. Phagocytosis of microconidia, small hyphal fragments, and yeast cells occurred 4 to 6 h after the infection of macrophage cultures. Conversion to the yeast phase began at 6 to 7 h and was complete after a 72-h incubation at 37 degrees C. Macrophages surrounded and adhered to macroconidia and large hyphal elements. More macrophages (65 to 68%) from BCG-treated mice contained fungi at 24 h than did macrophages from normal or vaccinated mice. Although there was no increase in the number of fungi in macrophages from vaccinated mice, only the macrophages from BCG-treated mice contained fewer fungi after 48 h of infection with the mycelial phase of H. capsulatum. Fungal growth was not inhibited in any of the macrophage cultures when infected with the yeast phase. The macrophages infected with yeast cells were destroyed after 48 to 72 h in the culture. Only BCG-treated macrophages survived infection with the mycelial phase, whereas macrophages from normal and vaccinated mice were destroyed by the infection.

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