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Integration of mycobacteriophage L5 requires the mycobacterial integration host factor (mIHF) in vitro. mIHF is a 105-residue heat-stable polypeptide that is not obviously related to HU or any other small DNA-binding proteins. mIHF is most abundant just prior to entry into stationary phase and is essential for the viability of Mycobacterium smegmatis.

We evaluated the effect of 2 years' therapy with an angiotensin converting enzyme inhibitor (captopril) in 16 patients who had severe reflux nephropathy and microalbuminuria. During the period of therapy, microalbuminuria decreased, glomerular filtration rate measured by diethylenetriamine pentaacetate scan, serum creatinine, and blood pressure remained stable. We suggest the captopril was useful in reducing microalbuminuria and may have slowed the progression of renal damage in our patients.

Lysogenization of mycobacteriophage L5 involves integration of the phage genome into the Mycobacterium smegmatis chromosome. Integration occurs by a site-specific recombination event between a phage attachment site, attP, and a bacterial attachment site, attB, which is catalyzed by the phage-encoded integrase protein. DNase I footprinting reveals that L5 integrase binds to two types of sites within attP which span an unexpectedly large region of 413 bp: seven arm-type sites (P1 to P7) each of which correspond to a consensus sequence 5'-TGCaaCtcYy, and core-type sites at the points of strand exchange. Mutational analyses indicate that not all of the arm-type sites are required for integration, and that the P3 site and the rightmost pair of sites (P6 and P7) are dispensable for integration. We show that a 252 bp segment of attP DNA is sufficient for efficient integrative recombination and that int can be provided in trans for simple and efficient transformation of the mycobacteria.

Bacterial integration host factors (IHFs) play central roles in the cellular processes of recombination, DNA replication, transcription, and bacterial pathogenesis. We describe here a novel mycobacterial IHF (mIHF) of Mycobacterium smegmatis and Mycobacterium tuberculosis that stimulates integration of mycobacteriophage L5. mIHF is the product of a single gene and is unrelated at the sequence level to other integration host factors. By itself, mIHF does not bind preferentially to attP DNA, although it significantly alters the pattern of integrase (Int) binding, promoting the formation of specific integrase-mIHF-attP intasome complexes.

The aim of this study was to investigate the relationship between plasma insulin levels, peripheral insulin sensitivity and androgen secretion in ten patients with polycystic ovary syndrome and in six obese women as compared with six normal-weight control subjects. During a euglycemic-hyper-insulinemic clamp no significant change of testosterone, androstenedione or dehydroepiandrosterone sulfate plasma levels was observed in the two groups of patients or in the control subjects; insulin sensitivity was clearly reduced and was similar in polycystic ovary patients and in obese women, in spite of the different plasma androgen levels. A long-term (5 months) androgen suppression with the gonadotropin-releasing hormone agonist leuprolide was not able to improve significantly the insulin sensitivity. These results demonstrate that the short-term hyperinsulinemia achieved with the clamp technique does not affect androgen secretion and that insulin resistance, measured with the same technique, is not influenced by long-term suppression of plasma androgen levels in polycystic ovary syndrome.