Tetracycline resistance encoded by four genetically different determinants residing on plasmids in Escherichia coli was shown to be associated in each case with an energy-dependent decrease in accumulation of the antibiotic in whole cells in which resistance had been induced. The different class determinants examined were those on plasmids RP1 (class A), R222 (class B), R144 (class C), and RAI (class D). This decrease in accumulation was attributable to an active efflux, because everted (inside-out) membrane vesicles made from tetracycline-induced E. coli cells containing any one of the four plasmids were shown to concentrate tetracycline by an active influx. This active uptake was not seen in inside-out vesicles from sensitive cells or uninduced R222-containing cells. In vesicles from induced R222-containing cells, the efflux appeared to be carrier-mediated with a Km of about 6 ;M. These results demonstrate that active export of tetracycline is a common component of the mechanism for tetracycline resistance encoded by different plasmid-borne determinants in bacteria. The tetracyclines are bacteriostatic antibiotics used to treat a broad spectrum of microbial disease agents in humans, animals, and plants (1). They act by inhibiting protein synthesis, specifically by preventing aminoacyl tRNA from binding to the A site on the ribosome during peptide elongation (2-4). Bacterial resistance to tetracycline is widespread and is caused by at least four different resistance determinants (5) carried on plasmids in the host bacterial cell. In most cases, resistance is inducible by subinhibitory amounts of tetracycline, and for some plasmids it can reach 200 times the resistance of plasmidless cells. The most common tetracycline resistance determinant in Escherichia coli appears to be that borne on transposon TnlO.t Plasmid-mediated tetracycline resistance does not lead to inactivation of the tetracycline molecule (6-8). Rather, resistance is associated with a decrease in tetracycline accumulation (8-11). A tetracycline-inducible inner membrane protein of molecular weight about 37,000, TET, is associated with TnlO-encoded resistance (8, 12), and a repressor activity of TET synthesis has been found (13). A TET protein of similar size encoded by other plasmid-borne resistance determinants has been described (8,12,(14)(15)(16).In previous work we showed two transport systems for tetracycline in sensitive E. coli K-12 cells, only one of which was sensitive to energy inhibitors (17). Both were altered by the tetracycline resistance plasmid R222 (11). The energy-dependent component of uptake in sensitive cells was replaced in resistant cells by a non-energy-requiring uptake of a lesser rate. In addition, the energy-independent uptake system in sensitive cells was decreased to 1/3-1/5 (11). This decrease appeared to be at least partly reversed by energy inhibitors (11), which suggested that energy was required for the lowered tetracycline accumulation. Using everted membrane vesicles, we now demonstrate that resistant...

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FOR THE 0008 STUDY GROUP*OBJECTIVE -This double-blind, placebo-controlled, randomized, multicenter, parallelgroup study compared the efficacy, safety, and tolerability of Technosphere insulin with Technosphere powder as placebo in insulin-naive type 2 diabetic patients whose diabetes was suboptimally controlled with oral antidiabetic agents.RESEARCH DESIGN AND METHODS -Patients (n ϭ 126) were randomly assigned to 12 weeks of therapy with Technosphere insulin or Technosphere powder after lifestyle education on nutrition, exercise, and instructions on inhaler use. The primary efficacy outcome was change in A1C from baseline to study end, and the secondary efficacy outcome was area under the curve for postprandial glucose levels during a meal test at treatment weeks 4, 8, and 12.RESULTS -A1C reduction from a mean baseline of 7.9% was greater with Technosphere insulin than with Technosphere powder (Ϫ0.72 vs. Ϫ0.30%; P ϭ 0.003). Postprandial glucose excursions were reduced by 56% with Technosphere insulin compared with baseline, and maximal postprandial glucose levels were reduced by 43% compared with Technosphere powder. Incidences of hypoglycemia, hyperglycemia, cough, and other adverse events were low in both groups. Body weight was unchanged in both groups.CONCLUSIONS -Technosphere insulin was well tolerated and demonstrated significant improvement in glycemic control with clinically meaningful reductions in A1C levels and postprandial glucose concentrations after 12 weeks of treatment.

Barriers to the use of prandial insulin regimens include inadequate synchronization of insulin action to postprandial plasma glucose excursions as well as a significant risk of hypoglycemia and weight gain. Technosphere® insulin (TI) is an inhaled ultra-rapid-acting human insulin that is quickly absorbed in the alveoli. With a time to maximum plasma drug concentration of approximately 14 min and a time to maximum effect of 35 to 40 min, TI more closely matches the postprandial insulin concentrations seen in nondiabetic individuals. Studies have shown that long-term administration of prandial TI in combination with long-acting basal insulin results in reductions in hemoglobin A1c comparable to conventional subcutaneously injected prandial insulins but with improved control of early postprandial BG. Furthermore, TI has been associated with less weight gain and a lower incidence of hypoglycemia, which may enhance patient satisfaction and acceptability of insulin therapy. This review discusses the clinical properties of TI and proposes strategies for optimal use.

This study demonstrated that, over 11 weeks, TI plus basal insulin glargine is well tolerated and results in dose-dependent reductions in postprandial glucose and HbA1c levels.