Human surfactant protein B promoter in transgenic mice: temporal, spatial, and stimulus-responsive regulation

Surfactant protein B (SP-B) is a developmentally and hormonally regulated lung protein that is required for normal surfactant function. We generated transgenic mice carrying the human SP-B promoter (-1,039/+431 bp) linked to chloramphenicol acetyltransferase (CAT). CAT activity was high in lung and immunoreactive protein localized to alveolar type II and bronchiolar epithelial cells. In addition, thyroid, trachea, and intestine demonstrated CAT activity, and each of these tissues also expressed low levels of SP-B mRNA. Developmental expression of CAT activity and SP-B mRNA in fetal lung were similar and both increased during explant culture. SP-B mRNA but not CAT activity decreased during culture of adult lung, and both were reduced by transforming growth factor (TGF)-beta(1). Treatment of adult mice with intratracheal bleomycin caused similar time-dependent decreases in lung SP-B mRNA and CAT activity. These findings indicate that the human SP-B promoter fragment directs tissue- and lung cell-specific transgene expression and contains cis-acting elements involved in regulated expression during development, fetal lung explant culture, and responsiveness to TGF-beta and bleomycin-induced lung injury.     

Efficacy and safety of a new vaginal contraceptive antimicrobial formulation containing high molecular weight poly(sodium 4-styrenesulfonate)

Host cell infection by sexually transmitted disease (STD)-causing microbes and fertilization by spermatozoa may have some mechanisms in common. If so, certain noncytotoxic agents could inhibit the functional activity of both organisms. High molecular mass poly(sodium 4-styrenesulfonate) (T-PSS) may be one of these compounds. T-PSS alone (1 mg/ml) or in a gel (2% or 5% T-PSS) completely prevented conception in the rabbit. Contraception was not due to sperm cytotoxicity or to an effect on sperm migration. However, T-PSS inhibited sperm hyaluronidase (IC(50) = 5.3 microg/ml) and acrosin (IC(50) = 0.3 microg/ml) and caused the loss of acrosomes from spermatozoa (85% maximal loss by 0.5 microg/ml). T-PSS (5% in gel) also reduced sperm penetration into bovine cervical mucus (73% inhibition by 1 mg gel/ml). T-PSS (5% in gel) inhibited human immunodeficiency virus (HIV; IC(50)= 16 microg gel/ml) and herpes simplex viruses (HSV-1 and HSV-2; IC(50) = 1.3 and 1.0 microg gel/ml, respectively). The drug showed high efficacy against a number of clinical isolates and laboratory strains. T-PSS (5% in gel) also inhibited Neisseria gonorrhea (IC(50) < 1.0 gel/ml) and Chlamydia trachomatis (IC(50) = 1.2 microg gel/ml) but had no effect on lactobacilli. These results imply that T-PSS is an effective functional inhibitor of both spermatozoa and certain STD-causing microbes. The noncytotoxic nature should make T-PSS safe for vaginal use. T-PSS was nonmutagenic in vitro and possessed an acute oral toxicity of >5 g/kg (rat). Gel with 10% T-PSS did not irritate the skin or penile mucosa (rabbit) and caused no dermal sensitization (guinea pig). Vaginal administration of the 5% T-PSS gel to the rabbit for 14 consecutive days caused no systemic toxicity and only mild (acceptable) vaginal irritation. T-PSS in gel form is worthy of clinical evaluation as a vaginal contraceptive HIV/STD preventative.     

Plasma 3-nitrotyrosine and outcome in neonates with severe bronchopulmonary dysplasia after inhaled nitric oxide

Plasma protein levels of 3-nitrotyrosine and 3-chlorotyrosine were measured by LC-MS/MS at 0 and 72 h after the initiation of inhaled nitric oxide (INO) at 20 ppm in 22 prematurely born infants with clinically documented bronchopulmonary dysplasia. Infants were classified at the time of hospital discharge as either "off mechanical ventilation," "on mechanical ventilation," or "expired/organ failure." These outcomes were tested for association with changes in plasma levels of 3-nitrotyrosine and 3-chlorotyrosine and selected clinical risk factors. Infants whose 3-nitrotyrosine levels decreased over the 72 h period were more likely to wean off of mechanical ventilation (p =.03). There was no significant association between changes in 3-chlorotyrosne levels and outcome. After controlling for other variables, an odds ratio of 8.3 (95% CI: 1.3-54.4) for improved outcomes was observed if the 3-nitrotyrosine levels decreased. These data suggest that nitrative and oxidative stress may be related to the severity of lung disease and, consequentially, the overall outcome in this select group of infants with severe bronchopulmonary dysplasia.     

Construction and Characterization of a 1,3-Propanediol Operon

The genes for the production of 1,3-propanediol (1,3-PD) in Klebsiella pneumoniae, dhaB, which encodes glycerol dehydratase, and dhaT, which encodes 1,3-PD oxidoreductase, are naturally under the control of two different promoters and are transcribed in different directions. These genes were reconfigured into an operon containing dhaB followed by dhaT under the control of a single promoter. The operon contains unique restriction sites to facilitate replacement of the promoter and other modifications. In a fed-batch cofermentation of glycerol and glucose, Escherichia coli containing the operon consumed 9.3 g of glycerol per liter and produced 6.3 g of 1,3-PD per liter. The fermentation had two distinct phases. In the first phase, significant cell growth occurred and the products were mainly 1,3-PD and acetate. In the second phase, very little growth occurred and the main products were 1,3-PD and pyruvate. The first enzyme in the 1,3-PD pathway, glycerol dehydratase, requires coenzyme B₁₂, which must be provided in E. coli fermentations. However, the amount of coenzyme B₁₂ needed was quite small, with 10 nM sufficient for good 1,3-PD production in batch cofermentations. 1,3-PD is a useful intermediate in the production of polyesters. The 1,3-PD operon was designed so that it can be readily modified for expression in other prokaryotic hosts; therefore, it is useful for metabolic engineering of 1,3-PD pathways from glycerol and other substrates such as glucose.     

Involvement of Both Dockerin Subdomains in Assembly of the Clostridium thermocellum Cellulosome

Clostridium thermocellum produces an extracellular cellulase complex termed the cellulosome. It consists of a scaffolding protein, CipA, containing nine cohesin domains and a cellulose-binding domain, and at least 14 different enzymatic subunits, each containing a conserved duplicated sequence, or dockerin domain. The cohesin-dockerin interaction is responsible for the assembly of the catalytic subunits into the cellulosome structure. Each duplicated sequence of the dockerin domain contains a region bearing homology to the EF-hand calcium-binding motif. Two subdomains, each containing a putative calcium-binding motif, were constructed from the dockerin domain of CelS, a major cellulosomal catalytic subunit. These subdomains, called DS1 and DS2, were cloned by PCR and expressed in Escherichia coli. The binding of DS1 and DS2 to R3, the third cohesin domain of CipA, was analyzed by nondenaturing gel electrophoresis. A stable complex was formed only when R3 was combined with both DS1 and DS2, indicating that the two halves of the dockerin domain interact with each other and such interaction is required for effective binding of the dockerin domain to the cohesin domain.