The Bacillus subtilis DivIVA protein targets to the division septum and controls the site specificity of cell division

The Bacillus subtilis divIVA gene, first defined by a mutation giving rise to anucleate minicells, has been cloned and characterized. Depletion of DivIVA leads to inhibition of the initiation of cell division. The residual divisions that do occur are abnormally placed and sometimes misorientated relative to the long axis of the cell. The DivIVA phenotype can be suppressed by disruption of the MinCD division inhibitor, suggesting that DivIVA controls the topological specificity of MinCD action and thus septum positioning. A DivIVA-GFP fusion targets to new and used sites of cell division, consistent with it having a direct role in topological specification.     

Crystal structures of substrate and substrate analog complexes of protocatechuate 3,4-dioxygenase: endogenous Fe3+ ligand displacement in response to substrate binding

Protocatechuate 3,4-dioxygenase (3,4-PCD) utilizes a ferric ion to catalyze the aromatic ring cleavage of 3,4-dihydroxybenzoate (PCA) by incorporation of both atoms of dioxygen to yield beta-carboxy-cis, cis-muconate. The crystal structures of the anaerobic 3,4-PCD.PCA complex, aerobic complexes with two heterocyclic PCA analogs, 2-hydroxyisonicotinic acid N-oxide (INO) and 6-hydroxynicotinic acid N-oxide (NNO), and ternary complexes of 3,4-PCD.INO.CN and 3,4-PCD. NNO.CN have been determined at 2.1-2.2 A resolution and refined to R-factors between 0.165 and 0.184. PCA, INO, and NNO form very similar, asymmetrically chelated complexes with the active site Fe3+ that result in dissociation of the endogenous axial tyrosinate Fe3+ ligand, Tyr447 (147beta). After its release from the iron, Tyr447 is stabilized by hydrogen bonding to Tyr16 (16alpha) and Asp413 (113beta) and forms the top of a small cavity adjacent to the C3-C4 bond of PCA. The equatorial Fe3+ coordination site within this cavity is unoccupied in the anaerobic 3,4-PCD.PCA complex but coordinates a solvent molecule in the 3,4-PCD.INO and 3,4-PCD.NNO complexes and CN- in the 3,4-PCD.INO.CN and 3,4-PCD.NNO.CN complexes. This shows that an O2 analog can occupy the cavity and suggests that electrophilic O2 attack on PCA is initiated from this site. Both the dissociation of the endogenous Tyr447 and the expansion of the iron coordination sphere are novel features of the 3,4-PCD. substrate complex which appear to play essential roles in the activation of substrate for O2 attack. Together, the structures presented here and in the preceding paper [Orville, A. M., Elango, N. , Lipscomb, J. D., & Ohlendorf, D. H. (1997) Biochemistry 36, 10039-10051] provide atomic models for several steps in the reaction cycle of 3,4-PCD and related Fe3+-containing dioxygenases.     

Surgical aspects of autonomic dysreflexia

Autonomic dysreflexia (AD) is a characteristic syndrome that occurs in spinal cord injury (SCI) patients with lesions above the sympathetic outflow at T6 and rarely in those with lesions below T10. Symptoms are initiated by noxious stimuli below the level of injury which result in massive sympathetic discharges from the isolated cord. These produce what may be called a sympathetic storm manifest by severe life threatening hypertension. Anesthesiologists and surgeons dealing with SCI patients must know how to recognize this syndrome, how to prevent its occurrence and how to manage it aggressively. Choice of anesthesia is frequently difficult and, in particular, it may be difficult to decide which type of anesthesia is best for patients susceptible to the syndrome. Therefore, we have conducted a retrospective study of SCI patients in the Department of Veterans Affairs Medical Center, Long Beach, California, where the Spinal Cord Injury Service is one of the largest in the country.     

Relationship between ABO blood group and levels of Gal alpha,3Galactose-reactive human immunoglobulin G

BACKGROUND: The terminal Gal alpha1,3Galactose (alphaGal) determinant is present on all porcine glycoproteins and glycolipids, but is not expressed by human cells. Consequently human sera contain anti-alphaGal natural antibodies. The human blood group B antigen [Gal alpha1,3(Fuc1,2)Galactose] is differentiated from the alphaGal epitope by the presence of a fucosyl group. METHODS: To determine whether the expression of the B antigen has any effect on the level of alphaGal-reactive natural antibodies, equal numbers (n=12) of A, B, AB, and O serum samples were evaluated by ELISA and flow cytometry. RESULTS: A significant reduction in IgG alphaGal reactivity was observed with serum samples from B antigen-expressing donors (B, AB) relative to non-B antigen-expressing donors (A, O). CONCLUSIONS: These results are consistent with the possibility that anti-alphaGal antibodies in non-B antigen-expressing individuals include a subset that is reactive with the structurally related B antigen and that this subset is absent in B and AB individuals.     

A paradigm of experimentally induced mild hyperthyroidism: effects on nitrogen balance, body composition, and energy expenditure in healthy young men

OBJECTIVE: To conceptualize, with fine needle aspiration cytology (FNAC), the early cellular events occurring in and around fresh autogenous and allogenic bone grafts during the first 40 postimplantation days. STUDY DESIGN: Forty-eight cases of bone grafts were studied by FNAC at serial intervals of 10, 20, 30 and 40 postimplantation days. Twenty patients were recipients of autogenous grafts, 16 received 0.6N HCI partially decalcified allogenic bone implants, and 4 received combined autogenous and allogenic bone grafts (included in the allograft group). There were eight control cases of closed fracture shaft femur, which were managed conservatively. RESULTS: The initial cellular responses in autogenous grafts, allografts and controls appear to be a part of the nonspecific reparative process followed by a more specific phase, with a steady increase in relative lymphocyte count from the 20th day onwards. Osteogenesis, as judged by osteoblasts and osteoclasts, was also comparable. CONCLUSION: Partially decalcified allografts appear to be a good substitute for autogenous bone grafts in clinical practice when adequate autogenous material is not available. FNAC is a good technique for studying bone graft responses without interfering with graft uptake. It is helpful in the early detection of subclinical infection or any other pathology at the graft site.     

Herpes simplex virus seropositivity and reactivation at delivery among pregnant women infected with human immunodeficiency virus-1

OBJECTIVE: Our purpose was to determine whether pregnant women infected with human immunodeficiency virus-1 have an increased risk of herpes simplex virus-2 seropositivity and herpes simplex virus reactivation at delivery. STUDY DESIGN: Sixty women infected with human immunodeficiency virus and 8408 other patients who were delivered at the University of Washington between 1989 and 1995 had herpes simplex virus serologic determinations at delivery. Genital herpes simplex virus cultures were obtained for 48 (80%) of the human immunodeficiency virus-infected women and 5567 (66%) of the controls. Logistic regression was used to adjust for possible confounding factors. RESULTS: Forty-five (75%) of human immunodeficiency virus-infected women and 2709 (32%) controls were seropositive for herpes simplex virus-2 (p < 0.0001). Eight percent of human immunodeficiency virus-infected women and 2% of controls had herpes simplex virus reactivation in labor (p < 0.05). CONCLUSIONS: Infection with herpes simplex virus-2 is common among pregnant women infected with human immunodeficiency virus. Herpes simplex virus reactivation complicates labor in this group more often than in other obstetric patients. The role of herpes simplex virus in perinatal human immunodeficiency virus transmission warrants further study.