Use of age and serum gamma-glutamyltransferase activity to assess passive transfer status in lambs.

OBJECTIVE: To develop an algorithm for predicting passive transfer status of lambs of various ages, using the lamb's age and serum gamma-glutamyltransferase (GGT) activity. DESIGN: Prospective study. ANIMALS: 51 Suffolk, Columbia, and crossbred lambs from 1 to 16 days old. PROCEDURE: Serum was obtained from all lambs. Serum GGT activity was measured, using a commercially available kit. Serum IgG concentration was determined by use of radial immunodiffusion. Day-1 serum IgG concentration was estimated from sample IgG concentration, lamb age, and the published 14-day half-life of IgG in lambs. Stepwise multivariate regression models were developed to estimate day-1 serum IgG concentration as a function of the natural logarithm of serum GGT activity (In[GGT]) and natural logarithm of lamb age (In[age]) at the time of sampling. These regression models were then used to calculate serum GGT activities that were equivalent to various day-1 IgG concentrations in lambs of various ages. RESULTS: In(GGT) and In(age) were significantly associated with estimated day-1 IgG concentration. Day-1 serum IgG concentration could be predicted using the formula: IgG = -7,686 + 1,366(In[GGT]) + 1,199(In[age]). The model was moderately accurate in predicting serum IgG concentration (R2 = 0.52). CLINICAL IMPLICATIONS: Serum GGT activity can be used to assess passive transfer status of lambs.

Transformation of Bartonella bacilliformis by electroporation.

Bartonella bacilliformis is a member of the order Rickettsiales, family Bartonellaceae. The bacterium is an intracellular parasite of human erythrocytes. To date, members of the family Bartonellaceae have not been transformed by standard chemical methods. We report the first successful transformation of a member of the Bartonellaceae family, B. bacilliformis, by the method of electroporation. The optimal conditions for electroporation of B. bacilliformis include a field strength of 12.5 kV/cm and a time constant of 5 ms using 0.2-cm cuvettes. With these parameters and the cosmid pEST (RK2 replicon), a transformation efficiency of 7.8 x 10(5) was obtained. Transformants were readily cultured on medium containing kanamycin sulfate at concentrations ranging from 15 to 600 micrograms/mL. Bacterial survival was approximately 31% under optimal electroporation conditions, and the maximal number of transformants was obtained with 80 ng of pEST DNA. Bartonella bacilliformis was verified as the transformed organism by a comparison of transformant protein profiles with those of wild-type B. bacilliformis using sodium dodecyl sulfate polyacrylamide gel electrophoresis, and detection of the exogenous plasmid in DNA from the transformed bacteria by DNA hybridization. Transformations using the plasmids pMK20, pML31, and pUCK18 (containing the replicons ColE1, F, and pMB1, respectively) were not successful.