The leader's role in implementing total quality management

Quality experts state that ineffective leadership can hinder and even destroy efforts to implement total quality management (TQM). However, they rarely discuss the specific actions leaders should take in implementing TQM and when leaders should take them. This article discusses a four-phase TQM implementation model that includes specifications for leadership actions at each step.     

Applying critical pathways to neurosurgery patients at the University of Michigan Medical Center

Project Overview: In April 1990, The University of Michigan Hospitals began a major, multidisciplinary project to standardize care processes in order to increase efficiency and reduce costs while maintaining the quality of clinical care. A team of nurses began the project by developing critical pathways for two neurosurgery procedures--lumbar laminectomy and transphenoidal pituitary tumor resection. The pathways were reviewed by physicians and other staff from other disciplines and were implemented in January of 1991. Key Findings: Data from the first 14 months show a decrease in patients' average lengths of stay in both the intensive care unit (ICU) and routine care unit. Costs and variance data are being analyzed and further improvements to the pathways are being made. Eleven critical paths are now being used for neurosurgery patients. In retrospect, participants learned that physicians should be involved at the earliest stages of critical pathway development and in the process of implementation.     

Panton-Valentine Leucocidin of Staphylococcus aureus Induces Oxidative Stress and Neurotransmitter Imbalance in a Retinal Explant Model

PurposeEndophthalmitis models have reported the virulent role of Panton-Valentine leucocidin (PVL) secreted by Staphylococcus aureus on the retina. PVL targets retinal ganglion cells (RGCs), expressing PVL membrane receptor C5aR. Interactions between PVL and retinal cells lead to glial activation, retinal inflammation, and apoptosis. In this study, we explored oxidative stress and retinal neurotransmitters in a rabbit retinal explant model incubated with PVL.MethodsReactive oxygen species (ROS) production in RGCs has been assessed with fluorescent probes and immunohistochemistry. Nuclear magnetic resonance (NMR) spectroscopy quantified retinal concentrations of antioxidant molecules and neurotransmitters, and concentrations of neurotransmitters released in the culture medium. Quantifying the expression of some pro-inflammatory and anti-inflammatory factors was performed using RT-qPCR.ResultsPVL induced a mitochondrial ROS production in RGCs after four hours’ incubation with the toxin. Enzymatic sources of ROS, involving nicotinamide adenine dinucleotide phosphate–oxidase and xanthine oxidase, were also activated after four hours in PVL-treated retinal explants. Retinal antioxidants defenses, that is, glutathione, ascorbate and taurine, decreased after two hours’ incubation with PVL. Glutamate retinal concentrations and glutamate release in the culture medium remained unaltered in PVL-treated retinas. GABA, glycine, and acetylcholine (Ach) retinal concentrations decreased after PVL treatment. Glycine release in the culture medium decreased, whereas Ach release increased after PVL treatment. Expression of proinflammatory and anti-inflammatory cytokines remained unchanged in PVL-treated explants.ConclusionsPVL activates oxidative pathways and alters neurotransmitter retinal concentrations and release, supporting the hypothesis that PVL could induce a neurogenic inflammation in the retina.     

Evolution of bacterial steroid biosynthesis and its impact on eukaryogenesis

Steroids are components of the eukaryotic cellular membrane and have indispensable roles in the process of eukaryotic endocytosis by regulating membrane fluidity and permeability. In particular, steroids may have been a structural prerequisite for the acquisition of mitochondria via endocytosis during eukaryogenesis. While eukaryotes are inferred to have evolved from an archaeal lineage, there is little similarity between the eukaryotic and archaeal cellular membranes. As such, the evolution of eukaryotic cellular membranes has limited our understanding of eukaryogenesis. Despite evolving from archaea, the eukaryotic cellular membrane is essentially a fatty acid bacterial-type membrane, which implies a substantial bacterial contribution to the evolution of the eukaryotic cellular membrane. Here, we address the evolution of steroid biosynthesis in eukaryotes by combining ancestral sequence reconstruction and comprehensive phylogenetic analyses of steroid biosynthesis genes. Contrary to the traditional assumption that eukaryotic steroid biosynthesis evolved within eukaryotes, most steroid biosynthesis genes are inferred to be derived from bacteria. In particular, aerobic deltaproteobacteria (myxobacteria) seem to have mediated the transfer of key genes for steroid biosynthesis to eukaryotes. Analyses of resurrected steroid biosynthesis enzymes suggest that the steroid biosynthesis pathway in early eukaryotes may have been similar to the pathway seen in modern plants and algae. These resurrected proteins also experimentally demonstrate that molecular oxygen was required to establish the modern eukaryotic cellular membrane during eukaryogenesis. Our study provides unique insight into relationships between early eukaryotes and other bacteria in addition to the well-known endosymbiosis with alphaproteobacteria.

The emergence of modern eukaryotic cells from their archaeal ancestor requires multiple evolutionary steps, most notably the acquisition of mitochondria, nucleus, endomembrane system, and bacterial-like cellular membranes. The acquisition of mitochondria by early eukaryotes before the last eukaryotic common ancestor (LECA) would have been a key step to exploit new resources within an aerobic environment (1). Similarly, the transformation of the eukaryotic cellular membrane system from an archaeal-type to bacterial-type membrane would have also been crucial to develop the dynamic cellular membrane system observed in modern eukaryotes (2). Such a dynamic membrane may have been the prerequisite for a pre-LECA cell to perform endocytosis and, hence, later acquire organelles such as mitochondria and chloroplasts. While the tetraether monolayer membrane in archaea is more rigid and is advantageous to harsh environments, such as high temperature and low pH conditions, the diester bilayer membrane found in bacteria and eukaryotes has been suggested to be adaptable to more general environments (3). Recent phylogenomic analyses of archaea and eukaryotes suggest that eukaryotes evolved from within the archaeal domain (4, 5). However, there is little similarity between the archaeal and the bacterial/eukaryotic cellular membranes. Both the stereochemistry of lipid molecules (i.e., phospholipids) and their lipid composition (e.g., fatty acid chain versus isoprenoid chain and the presence of sphingolipids and steroids) are fundamentally different between the two types of membranes. As such, the evolutionary history of the eukaryotic cellular membrane is a major gap in our understanding of eukaryogenesis (6).Here, we focus on the evolution of the steroid component of the eukaryotic cellular membrane. Steroids have indispensable roles in the process of eukaryotic endocytosis because they are embedded in the cellular membrane and are known to regulate membrane fluidity and permeability (7–9). Thus, steroids may also have been integral for the endocytic process to acquire mitochondria during eukaryogenesis. Steroids would also function as hormones to control various cellular processes, including differentiation, morphogenesis, and homeostasis to enable multicellularity (10). In addition to the vital biochemical role in modern eukaryotes, steroids also have a geobiological importance. They can serve as unique biological markers (biomarkers) for eukaryotes in the geological record and thus provide clues to trace the evolutionary history of eukaryotes on a geological time scale. Membrane-bound steroids are modified in a unique manner within each eukaryotic taxon. For instance, cholesterol is a major component of cellular membrane in metazoans, whereas stigmasterol is a major component in plants (11, 12). These taxon-specific modifications can be used as taxonomic markers in the geological record (13–15). No analogous steroid biosynthesis pathway has been observed in archaea and thus steroid biosynthesis is generally inferred to have evolved de novo within eukaryotes (16). Despite this inference, some bacteria are known to produce hopanoids that are structurally similar to steroids (17). Indeed, several genes that are involved in hopanoid and steroid biosynthesis are suggested to have been horizontally transferred from bacteria to eukaryotes (18, 19). These recent observations suggest a more complex evolutionary history of steroid biosynthesis in eukaryotes. Ancestral sequence reconstruction (ASR) enables us to experimentally analyze resurrected enzymes (20, 21) and thus infer evolutionary histories of steroid biosynthesis and their impacts on eukaryogenesis.     

Identification of new type 2B von Willebrand disease mutations: Arg543Gln, Arg545Pro and Arg578Leu

We report the identification in five patients (three families) affected with type 2B von Willebrand disease (VWD) of three heterozygous nucleotide substitutions at the codon for arginine 543, 545 and 578 of the mature von Willebrand factor (VWF) subunit resulting in a glutamine, proline and leucine substitution, respectively. These mutations are located in the A1 loop where prevalent type 2B mutations (Arg543Trp, Arg545Cys and Arg578Gln) have been already identified at the same positions. By in vitro mutagenesis of full-length cDNA of VWF and transient expression in Cos-7 cells, we have shown that the six corresponding mutated recombinant VWFs (Gln543, Trp543, Cys545, Pro545, Leu578 and Gln578 rVWF) exhibited quantitatively normal expression and normal multimeric pattern but increased ristocetin- and botrocetin-induced binding to platelets as compared with that for wild-type rVWF. The two mutations at position 545 induced the greatest reactivity for GPIb of corresponding rVWFs as compared to the two mutations at positions 543 and 578.     

Hereditary diffuse articular chondrocalcinosis. Dominant manifestation without close linkage with the HLA system in a large pedigree

Thirty-nine members of one family, covering three generations, were HLA-typed. Twenty-five suffered from primary diffuse articular chondrocalcinosis, and all had the same dominantly transmitted autosomally controlled disease. This was characterized by acute articular attacks, which always started before the age of 35, and radiologically by typical cartilaginous and fibrocartilaginous deposits associated with para-articular calcifications. The lesions were both peripherally and axially generalized. None of the 28 HLA antigens tested seemed related to the disease, nor did the disease segregate with an HLA haplotype.