What is the true in vitro potency of oxytetracycline for the pig pneumonia pathogens Actinobacillus pleuropneumoniae and Pasteurella multocida?

The pharmacodynamics of oxytetracycline was determined for pig respiratory tract pathogens, Actinobacillus pleuropneumoniae and Pasteurella multocida. Indices of potency were determined for the following: (i) two matrices, broth and pig serum; (ii) five overlapping sets of twofold dilutions; and (iii) a high strength starting culture. For A. pleuropneumoniae, minimum inhibitory concentration (MIC) was similar for the two matrices, but for P. multocida, differences were marked and significantly different. MIC and minimum bactericidal concentration (MBC) serum: broth ratios for A. pleuropneumoniae were 0.83:1 and 1.22:1, respectively, and corresponding values for P. multocida were 22.0:1 and 7.34:1. For mutant prevention concentration (MPC) serum: broth ratios were 0.79:1 (A. pleuropneumoniae) and 20.9:1 (P. multocida). These ratios were corrected for serum protein binding to yield fraction unbound (fu) serum: broth MIC ratios of 0.24:1 (A. pleuropneumoniae) and 6.30:1 (P. multocida). Corresponding fu serum: broth ratios for MPC were almost identical, 0.23:1 and 6.08:1. These corrections for protein binding did not account for potency differences between serum and broth for either species; based on fu serum MICs, potency in serum was approximately fourfold greater than predicted for A. pleuropneumoniae and sixfold smaller than predicted for P. multocida. For both broth and serum and both bacterial species, MICs were also dependent on initial inoculum strength. The killing action of oxytetracycline had the characteristics of codependency for both A. pleuropneumoniae and P. multocida in both growth media. The in vitro potency of oxytetracycline in pig serum is likely to be closer to the in vivo plasma/serum concentration required for efficacy than potency estimated in broths.     

Declines in dietary macronutrient intake in persons with HIV infection who develop depression

BACKGROUND: The effect of depression on dietary intake has not, to our knowledge, been examined in persons with HIV infection. METHODS: We conducted a longitudinal analysis of participants in the Nutrition for Healthy Living Study (NFHL). We measured changes in dietary macronutrient intake in participants who developed depression and, using multiple regression analysis, compared the changes with a control group of patients who did not become depressed. RESULTS: Ninety patients developed depression during the observation period, and we compared these with 152 non-depressed controls. The two groups had similar age and body mass index (BMI) at baseline, but those who developed depression were more likely to be female, less educated and had lower incomes. After adjustment, compared with non-depressed participants, those who developed depression had significantly greater decreases in the following daily intakes: total energy (-341 kcal, P = 0.006), protein (-12.3 g, P = 0.02), total fat (-18.5 g, P = 0.008), carbohydrate (-36.8 g, P = 0.02), total fibre (-4.3 g, P = 0.001) and saturated fat (-6.7 g, P = 0.01). There were no significant differences in the daily intakes of simple sugars and long-chain n-3 fatty acids, or BMI. CONCLUSION: Depression is associated with decreases in total daily energy intake and in six of the eight dietary components we measured. Clinicians should be aware that depression-associated nutritional deficiencies may complicate the care of persons with HIV.     

Reticular groove contraction in dairy cattle following drenching with an anti-bloat solution or a combination of anti-bloat solution and NaCl

AIM: To determine whether the inclusion of NaCl in an antibloat drench increased the incidence of contraction of the reticular (oesophageal) groove in cattle. METHODS: Non-lactating Friesian dairy cows aged 3-10 years (n=30) were subjected to a 13C-octanoic-acid breath test after being drenched with either an anti-bloat solution alone or a mixture of anti-bloat solution and NaCl, to determine the incidence of reticular groove contraction. RESULTS: Drenching with an anti-bloat solution alone did not result in detectable by-pass of the reticulorumen in 27/29 cows; minor by-pass occurred in 2/29 cows. The inclusion of NaCl in the anti-bloat solution increased the incidence of reticulorumen by-pass; minor by-pass occurred in 12/30 cows and substantial by-pass was detected in 5/30 cows. The incidence of by-pass did not vary significantly with cow age. CONCLUSIONS: Drenching with an anti-bloat solution alone did not result in significant by-pass of the reticulorumen. The inclusion of NaCl in the anti-bloat drench increased the incidence of reticulorumen by-pass. The proportion of anti-bloat/ NaCl fluid by-passed was considered to be of no practical significance to the protection from bloat afforded in the majority of animals, but may significantly decrease protection from bloat afforded by drenching in 10-15% of cows. The proportion of animals at risk within a herd may vary with their physiological state and the method and frequency (number of doses per drench) of drenching.     

Effects of extended postmortem aging and intramuscular location on protein degradation,muscle fiber morphometrics,and tenderness of beef longissimus lumborum and semitendinosus steaks

The objective of this study was to determine effects of extended aging and intramuscular location on Warner-Bratzler shear force (WBSF), muscle fiber cross-sectional area (CSA), and protein degradation of semitendinosus (ST) and longissimus lumborum (LL) steaks. Left ST and LL were removed from 40 carcasses at 6 d postmortem. The ST was fabricated into five locations (LOC), with LOC 1 being most proximal and LOC 5 being most distal. The posterior LL was fabricated into 3 LOC, with LOC 1 being most anterior. Vacuum sealed ST steaks were aged 7, 14, 28, 56, or 112 d postmortem, while LL steaks were aged 7, 28, or 112 d postmortem at 2 ± 1 °C. A steak from each LOC was assigned to WBSF or laboratory analyses. There were no Day of Aging (DOA) × LOC interactions for all dependent variables (P > 0.06). There were DOA effects for ST and LL WBSF values and degraded 38-kDa desmin (DES; P < 0.01). Day-7 ST-steak WBSF value was greater than all other days (P < 0.01) and day-14 steaks had greater WBSF value than remaining days (P < 0.05). Day-28 ST-steak WBSF values were greater than day 56 and 112 (P < 0.01), which did not differ (P = 0.53). In the LL, day-7 steaks had greater WBSF values than the other two timepoints (P < 0.01) and day-28 steaks had greater (P < 0.01) WBSF values than day-112 steaks. Degraded ST 38-kDa DES content was less on day 7 and 14 compared to all other days (P < 0.03), but did not differ (P = 0.79) from each other. Days 28 and 56 38-kDa DES content was less than day 112 (P < 0.01), but did not differ (P = 0.34) from each other. Degraded LL 38-kDa DES content was less on day 7 than day 28 and 112 (P < 0.02), which did not differ (P = 0.67). There were LOC effects for only ST WBSF and muscle fiber CSA (P < 0.05). Semitendinosus steak LOC 1 and 2 had greater WBSF values than all other locations (P < 0.01), but did not differ (P = 0.32) from each other. Semitendinosus steak LOC 3 and 5 had greater WBSF values than LOC 4 (P < 0.01), but did not differ (P = 0.85) from each other. The CSA of all ST fiber types were largest in LOC 1 compared to all other fiber types (P < 0.01). The CSA of all LOC 2 and 3 fiber types was greater than LOC 4 and 5 (P < 0.01), but were not different from each other (P > 0.81), and LOC 4 had greater CSA than LOC 5 (P < 0.01). Steak aging WBSF value improvements seemed proteolysis catalyzed, while the ST intramuscular tenderness gradient was more likely due to muscle fiber CSA.     

Surgery of metastatic anal sac adenocarcinoma in five dogs

OBJECTIVE: To identify survival and morbidity information after surgery for metastases from apocrine gland anal sac adenocarcinomas (AGACA). STUDY DESIGN: Retrospective study. ANIMALS: Five dogs with AGACA. METHODS: Medical records of dogs that had surgery for treatment of metastatic AGACA between 1993 and 2003 were reviewed. Criteria for inclusion required that dogs had lymphadenectomy, with or without further debulking, as part of their treatment for metastatic AGACA and that the tissue was histologically confirmed as consistent with the primary AGACA. Signalment, history, physical examination findings, clinicopathologic data, imaging findings, surgical complications, number of surgeries, survival times, and cause of death were recorded. All dogs had a complete blood count, serum biochemical profile, serum electrolytes, 3-projection thoracic radiographs, abdominal radiographs and/or abdominal ultrasonography, and histologic confirmation of metastatic AGACA invading the regional lymph nodes and caudal abdomen. RESULTS: No surgical complications occurred. Three dogs were euthanatized; median survival, 20.6 months. One dog was alive for 19 months postoperatively. One dog had 5 sequential surgical procedures: 1 iliac lymphadenectomy and 4 debulking procedures of metastatic neoplastic tissue around and dorsal to the iliac vessels extending into the pelvic cavity, and was alive 54 months after initial surgery. CONCLUSION: Dogs with anal sac adenocarcinoma metastases to the iliac lymph nodes can experience long-term survival after surgical excision of the metastatic lesion. CLINICAL RELEVANCE: Lymphadenectomy may afford long-term survival to patients with metastatic anal sac adenocarcinoma.     

Role of the sphingosine-1-phosphate receptor EDG-1 in PDGF-induced cell motility

EDG-1 is a heterotrimeric guanine nucleotide binding protein-coupled receptor (GPCR) for sphingosine-1-phosphate (SPP). Cell migration toward platelet-derived growth factor (PDGF), which stimulates sphingosine kinase and increases intracellular SPP, was dependent on expression of EDG-1. Deletion of edg-1 or inhibition of sphingosine kinase suppressed chemotaxis toward PDGF and also activation of the small guanosine triphosphatase Rac, which is essential for protrusion of lamellipodia and forward movement. Moreover, PDGF activated EDG-1, as measured by translocation of beta-arrestin and phosphorylation of EDG-1. Our results reveal a role for receptor cross-communication in which activation of a GPCR by a receptor tyrosine kinase is critical for cell motility.