The phospholipid composition of the cell membrane influences the spatial and temporal biochemistry of cells. We studied molecular mechanisms connecting membrane composition to cell morphology in the model bacterium Rhodobacter sphaeroides. The peptidoglycan (PG) layer of the cell wall is a dominant component of cell mechanical properties; consequently, it has been an important antibiotic target. We found that the anionic phospholipid cardiolipin (CL) plays a role in determination of the shape of R. sphaeroides cells by affecting PG precursor biosynthesis. Removing CL in R. sphaeroides alters cell morphology and increases its sensitivity to antibiotics targeting proteins synthesizing PG. These studies provide a connection to spatial biochemical control in mitochondria, which contain an inner membrane with topological features in common with R. sphaeroides.

Between January 1965 and August 1977, 122 patients with 135 arterial emboli were treated on the Peripheral Vascular Service at the Ohio State University Hospital. The heart was the source of the embolus in 94 patients (77%), one-third of whom had experienced a myocardial infarct. Thirteen patients died after the operation, which in 102 patients (84%) consisted of embolectomy only, making the hospital mortality 10.6%. Fourteen patients (11.5%) required subsequent amputations during the same hospitalization or on a later admission. The corrected limb salvage rate of 80.9% was unrelated to the length of delay in presentation. Although only 70 patients (57.4%) had palpable distal pulses following operation, 89 (73%) had a functional limb at the time of discharge or on later follow-up. An aggressive approach to the patient with an arterial embolus, regardless of the duration of symptoms, is urged. Embolectomy under local anesthesia is advocated in all cases after prompt correction of fluid and electrolyte imbalance and stabilization of the underlying cardiac disorder, except in patients with frank gangrene and irreversible rigor. In the absence of distal pulses or obvious revascularization, an intraoperative arteriogram is mandatory.

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The optimal anesthetic for use during carotid endarterectomy has been a matter of debate for three decades. The goal of this study is to evaluate the influence of anesthetic technique on perioperative hemodynamic instability after carotid endarterectomy. This study is a retrospective chart review and was performed in a community teaching hospital. All consecutive patients undergoing carotid endarterectomy over a 2-year period at Providence Hospital were reviewed. One hundred ninety-eight patients underwent 203 carotid endarterectomies. Two patients were excluded because of combined coronary artery bypass grafting. Patients underwent carotid endarterectomy and were divided into two groups on the basis of use of general or regional anesthesia. Blood pressure was recorded hourly for the subsequent 24 hours, and the doses of vasoactive medications received to maintain the blood pressure within 25 mm Hg of preoperative levels were recorded. Patients receiving general anesthesia were found to require significantly more sodium nitroprusside for control of hypertension compared with those receiving regional anesthesia (72.1 ± 14.5 μg/kg vs 20.2 ± 6.6 ug/kg; P = 0.001) in the first 8 postoperative hours. No significant differences were noted in the doses of any other vasoactive medications used. No differences were found in the subsequent 16-hour period in doses of vasoactive medications. Patients suffering myocardial infarctions were found to receive higher doses of nitroglycerine, but no differences were noted in any other vasoactive medication used based on complications. Length of stay was longer in the general anesthesia group compared with the regional anesthesia group for both the intensive care unit (1.59 ± 0.13 days vs 1.08 ± 0.03 days; P = 0.001) and total hospital stay (5.8 ± 0.03 days vs 4.5 ± 0.02 days; P = 0.003). Regional anesthesia required lower doses of antihypertensive medication in the early postoperative period when compared with general anesthesia. The doses of vasoactive medications used had no significant impact on the complication rate. Regional anesthesia allowed for shorter stay in both the intensive care unit and total hospital stay.

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We report the design and characterization of Fe-containing soft materials that respond to, interface with, and/or sequester Fe-chelating “siderophores” that bacteria use to scavenge for iron and regulate iron homeostasis. We demonstrate that metal–organic network coatings fabricated by cross-linking tannic acid with iron­(III) are stable in bacterial growth media but erode upon exposure to biologically relevant concentrations of enterobactin and deferoxamine B, two siderophores produced by Gram-negative and Gram-positive bacteria, respectively. Our results are consistent with changes in network stability triggered by the extraction of iron­(III) and reveal rates of siderophore-induced disassembly to depend upon both siderophore concentration and affinity for iron­(III). These coatings also disassemble when incubated in the presence of cultures of wild-type Escherichia coli. Assays using genetically modified strains of E. coli reveal the erosion of these materials by live cultures to be promoted by secretion of enterobactin and not from other factors resulting from bacterial growth and metabolism. This stimuli-responsive behavior can also be exploited to design coatings that release the Fe-chelating antibiotic ciprofloxacin into bacterial cultures. Finally, we report the discovery of Fe-containing polymer hydrogels that avidly sequester and scavenge enterobactin from surrounding media. The materials reported here (i) are capable of interfacing or interfering with mechanisms that bacteria use to maintain iron homeostasis, either by yielding iron to or by sequestering iron-scavenging agents from bacteria, and (ii) can respond dynamically to or report on the presence of populations of iron-scavenging bacteria. Our results thus provide new tools that could prove useful for microbiological research and enable new stimuli-responsive strategies for interfacing with or controlling the behaviors of communities of iron-scavenging bacteria.

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