Jean Burckhardt

Genes whose expression is growth factor regulated are likely to be important components in the mechanisms controlling cell proliferation and differentiation. With the aim of identifying some of those genes, a lambda cDNA library was prepared with poly(A)+ RNA from quiescent NIH 3T3 cells stimulated with serum for 4 h in the presence of cycloheximide. Differential screening of approximately 200,000 recombinant phage plaques revealed 2,540 clones that cross hybridized preferentially with [32P]cDNA derived from RNA of stimulated cells rather than with cDNA derived from nonstimulated cells. Cross hybridization of these clones identified 82 independent sequences, including c-fos and c-myc. Seventy-one clones were further studied. Analysis of the changes in transcription and mRNA levels after serum stimulation demonstrated that the kinetics and extent of the induction vary dramatically between the different genes. Cycloheximide in all cases superinduced the mRNA levels by two mechanisms, inhibiting the shutoff of transcription and prolonging the half-lives of the mRNAs. Our results showed that induction of proliferation is accompanied by the onset of a complex genetic program.

Human African trypanosomiasis (HAT) is transmitted by tsetse flies and, if untreated, is fatal. Treatment depends on infection stage, and early diagnosis is crucial for effective disease management. The systemic host biochemical changes induced by HAT that enable biomarker discovery or relate to therapeutic outcome are largely unknown. We have characterized the multivariate temporal responses of mice to Trypanosoma brucei brucei infection, using (1)H nuclear magnetic resonance (NMR) spectroscopic metabolic phenotyping of urine and plasma. Marked alterations in plasma metabolic profiles were detected already 1 day postinfection. Elevated plasma concentrations of lactate, branched chain amino acids, and acetylglycoprotein fragments were noted. T. brucei brucei-infected mice also had an imbalance of plasma alanine and valine, consistent with differential gluconeogenesis (parasite)-ketogenesis (host) pathway counterflux, involving stimulated host glycolysis, ketogenesis, and enhanced lipid oxidation in the host. Histopathologic evidence of T. brucei brucei-induced extramedullary hepatic hemopoiesis, renal interstitial nephritis, and a provoked inflammatory response was also noted. Metabolic disturbance of gut microbiotal activity was associated with infection, as indicated by changes in the urinary concentrations of the microbial co-metabolites, including hippurate. Concluding, parasite infection results in multiple systemic biochemical effects in the host and disturbance of the symbiotic gut microbial metabolic interactions. Investigation of these transgenomic metabolic alterations may underpin the development of new diagnostic criteria and metrics of therapeutic efficacy.