Comparison of the effect of bacterial inoculation in musculocutaneous and random-pattern flaps

The response of musculocutaneous and random-pattern flaps to bacterial inoculation was studied in dogs by intradermal injection of bacteria and deposition of bacteria into stable wound spaces created by wound cylinders. No difference could be demonstrated in the susceptibility to bacterial challenge in the different portions of the musculocutaneous flap and in normal skin. A larger area of necrosis was observed in the random-pattern flaps, and the distal part was significantly more susceptible to necrosis. While the musculocutaneous flaps recovered rapidly from the bacterial inoculation, necrosis was observed in the random-pattern flaps. The bacterial count increased in the wound spaces surrounded by the random-pattern flaps, leading to full-thickness flap necrosis. The bacterial count decreased in the wound spaces surrounded by musculocutaneous flaps; there was evidence of healing around the wound cylinders. The musculocutaneous flap demonstrates a greater resistance to bacterial inoculation than the random-pattern flap on both its cutaneous and muscular surfaces.

The endoplasmic reticulum in apoptosis and autophagy: role of the BCL-2 protein family

Apoptosis is essential for normal development and maintenance of homeostasis, and disruption of apoptotic pathways is associated with multiple disease states, including cancer. Although initially identified as central regulators of apoptosis at the level of mitochondria, an important role for BCL-2 proteins at the endoplasmic reticulum is now well established. Signaling pathways emanating from the endoplasmic reticulum (ER) are involved in apoptosis initiated by stimuli as diverse as ER stress, oncogene expression, death receptor (DR) ligation and oxidative stress, and the BCL-2 family is almost invariably implicated in the regulation of these pathways. This also includes Ca(2+)-mediated cross talk between ER and mitochondria during apoptosis, which contributes to the mitochondrial dynamics that support the core mitochondrial apoptosis pathway. In addition to the regulation of apoptosis, BCL-2 proteins at the ER also regulate autophagy, a survival pathway that limits metabolic stress, genomic instability and tumorigenesis. In cases where apoptosis is inhibited, however, prolonged autophagy can lead to cell death. This review provides an overview of ER-associated apoptotic and autophagic signaling pathways, with particular emphasis on the BCL-2 family proteins.

A macrophage protein, Ym1, transiently expressed during inflammation is a novel mammalian lectin

Oral infections of mice with Trichinella spiralis induce activation of peritoneal exudate cells to transiently express and secrete a crystallizable protein Ym1. Purification of Ym1 to homogeneity was achieved. It is a single chain polypeptide (45 kDa) with a strong tendency to crystallize at its isoelectric point (pI 5.7). Co-expression of Ym1 with Mac-1 and scavenger receptor pinpoints macrophages as its main producer. Protein microsequencing data provide information required for full-length cDNA cloning from libraries constructed from activated peritoneal exudate cells. A single open reading frame of 398 amino acids with a leader peptide (21 residues) typical of secretory protein was deduced and later deposited in GenBank (accession number M94584) in 1992. By means of surface plasmon resonance analyses, Ym1 has been shown to exhibit binding specificity to saccharides with a free amine group, such as GlcN, GalN, or GlcN polymers, but it failed to bind to other saccharides. The interaction is pH-dependent but Ca2+ and Mg2+ ion-independent. The binding avidity of Ym1 to GlcN oligosaccharides was enhanced by more than 1000-fold due to the clustering effect. Specific binding of Ym1 to heparin suggests that heparin/heparan sulfate may be its physiological ligand in vivo during inflammation and/or tissue remodeling. Although it shares approximately 30% homology with microbial chitinases, no chitinase activity was found associated with Ym1. Genomic Southern blot analyses suggest that Ym1 may represent a member of a novel lectin gene family.

Development of a Canadian standardized protocol for subtyping methicillin-resistant Staphylococcus aureus using pulsed-field gel electrophoresis

A panel of 24 methicillin-resistant Staphylococcus aureus strains was distributed to 15 laboratories in Canada to evaluate their in-house pulsed-field gel electrophoresis (PFGE) protocols and interpretation criteria. Attempts to compare fingerprint images using computer-aided analysis were not successful due to variability in individual laboratory PFGE protocols. In addition, individual site interpretation of the fingerprint patterns was inadequate, as 7 of 13 sites (54%) made at least one error in interpreting the fingerprints from the panel. A 2-day standardized PFGE protocol (culture to gel image) was developed and distributed to all of the sites. Each site was requested to use the standardized protocol on five strains from the original panel. Thirteen sites submitted gel images for comparisons. The protocol demonstrated excellent reproducibility and allowed interlaboratory comparisons with Molecular Analyst DST software (Bio-Rad) and 1.5% band tolerance.

Direct measurement of wound and tissue oxygen tension in postoperative patients

An implanted Silastic catheter technique was used to measure partial pressure of oxygen in mastectomy wounds and needle-induced wounds in the subcutaneous tissue of the arms of 33 postoperative patients to assess tissue-wound oxygenation and perfusion on the day of operation and daily through postoperative day five. Characteristic patterns were observed. Wound hypoxia was common and most pronounced after abdominal, vascular, and cardiac procedures. It was most severe immediately after operation. Tissue hypoxia was not easily detected by clinical evaluation and was unknowingly tolerated by experienced surgeons. The relationship between arterial and tissue PO2 is biphasic and presumably curvilinear at the lower range of PaO2 and rises linearly even above the point of full saturation of hemoglobin. Supplemental bolus fluid infusion elevated depressed tissue PO2 in 19 out of 19 measurements, implicating hypovolemia as a common cause of postoperative tissue hypoxia. Measurements of tissue oxygen tension, coupled with a single arterial oxygen determination, constitute a clinically useful means of monitoring tissue perfusion.

Comparison of the effect of bacterial inoculation in musculocutaneous and fasciocutaneous flaps

The skin fascial flap is now recognized as a reliable flap for use in reconstructive surgery. The fasciocutaneous flap has been advocated for coverage of chronic infected wounds after debridement as an alternative to the musculocutaneous flap. Previous experimental and clinical studies have demonstrated the superior resistance of the musculocutaneous flap as compared to the random-pattern flap to bacterial inoculation. A canine model is presented for comparison of the effect of bacterial inoculation in fasciocutaneous and musculocutaneous flaps of similar dimensions. The area of skin necrosis secondary to bacterial inoculation was similar in these two flap types despite greater blood flow and skin oxygen in the fasciocutaneous flap. In a study of closed wound spaces formed by the deep surface of these two flap types, a greater degree of inhibition and elimination of bacterial growth and more collagen deposition are observed in the musculocutaneous wound space than in the fasciocutaneous flap.

Construction of a Helicobacter pylori genome map and demonstration of diversity at the genome level

Genomic DNA from 30 strains of Helicobacter pylori was subjected to pulsed-field gel electrophoresis (PFGE) after digestion with NotI and NruI. The genome sizes of the strains ranged from 1.6 to 1.73 Mb, with an average size of 1.67 Mb. By using NotI and NruI, a circular map of H. pylori UA802 (1.7 Mb) which contained three copies of 16S and 23S rRNA genes was constructed. An unusual feature of the H. pylori genome was the separate location of at least two copies of 16S and 23S rRNA genes. Almost all strains had different PFGE patterns after NotI and NruI digestion, suggesting that the H. pylori genome possesses a considerable degree of genetic variability. However, three strains from different sites (the fundus, antrum, and body of the stomach) within the same patient gave identical PFGE patterns. The genomic pattern of individual isolates remained constant during multiple subcultures in vitro. The reason for the genetic diversity observed among H. pylori strains remains to be explained.

The synthesis and thermolysis of imidazole quaternary salts

The pyrolysis of imidazolium halides substituted on the nitrogen atoms by alkyl or aryl groups leads to 1-substituted imidazoles. Differing substituents cleave at different rates, while the nature of the anion and the influence of substituents at C4 modify the reaction products. Tetraphenylborate and perchlorate salts fail to dealkylate. An SN2 (or SN2?) mechanism appears to be the most likely for the process.

Chimeric antibody with human constant regions and mouse variable regions directed against carcinoma-associated antigen 17-1A

We have cloned the genomic DNA fragments encoding the heavy and light chain variable regions of monoclonal antibody 17-1A, and we have inserted them into mammalian expression vectors containing genomic DNA segments encoding human gamma 3 and kappa constant regions. The transfer of these expression vectors containing mouse-human chimeric immunoglobulin genes into Sp2/0 mouse myeloma cells resulted in the production of functional IgG that retained the specific binding to the surface antigen 17-1A expressed on colorectal carcinoma cells.

Pulsed-field gel electrophoresis of Campylobacter jejuni and Campylobacter coli genomic DNA and its epidemiologic application

Genomic DNA from 12 different Campylobacter jejuni and 10 Campylobacter coli isolates was digested with SmaI and analyzed by pulsed-field gel electrophoresis (PFGE) and 16S rRNA hybridization studies. Although the two Campylobacter species displayed species-specific restriction and hybridization patterns, significant intraspecies differences were observed. Combined PFGE and hybridization pattern analysis failed to provide any more epidemiologic information than was obtained from PFGE restriction profiles alone. Therefore, results from these studies indicate that PFGE analysis of SmaI-restricted genomic DNA provides a reliable means of differentiating C. jejuni from C. coli and may represent a more practical approach to epidemiologic studies than combining conventional DNA restriction digestion pattern with RNA hybridization procedures.

mu-conotoxin GIIIA interactions with the voltage-gated Na(+) channel predict a clockwise arrangement of the domains

Voltage-gated Na(+) channels underlie the electrical activity of most excitable cells, and these channels are the targets of many antiarrhythmic, anticonvulsant, and local anesthetic drugs. The channel pore is formed by a single polypeptide chain, containing four different, but homologous domains that are thought to arrange themselves circumferentially to form the ion permeation pathway. Although several structural models have been proposed, there has been no agreement concerning whether the four domains are arranged in a clockwise or a counterclockwise pattern around the pore, which is a fundamental question about the tertiary structure of the channel. We have probed the local architecture of the rat adult skeletal muscle Na(+) channel (mu1) outer vestibule and selectivity filter using mu-conotoxin GIIIA (mu-CTX), a neurotoxin of known structure that binds in this region. Interactions between the pore-forming loops from three different domains and four toxin residues were distinguished by mutant cycle analysis. Three of these residues, Gln-14, Hydroxyproline-17 (Hyp-17), and Lys-16 are arranged approximately at right angles to each other in a plane above the critical Arg-13 that binds directly in the ion permeation pathway. Interaction points were identified between Hyp-17 and channel residue Met-1240 of domain III and between Lys-16 and Glu-403 of domain I and Asp-1532 of domain IV. These interactions were estimated to contribute -1.0+/-0.1, -0.9+/-0.3, and -1.4+/-0.1 kcal/mol of coupling energy to the native toxin-channel complex, respectively. mu-CTX residues Gln-14 and Arg-1, both on the same side of the toxin molecule, interacted with Thr-759 of domain II. Three analytical approaches to the pattern of interactions predict that the channel domains most probably are arranged in a clockwise configuration around the pore as viewed from the extracellular surface.

The crystal structure of a novel mammalian lectin, Ym1, suggests a saccharide binding site

Ym1, a secretory protein synthesized by activated murine peritoneal macrophages, is a novel mammalian lectin with a binding specificity to GlcN. Lectins are responsible for carbohydrate recognition and for mediating cell-cell and cell-extracellular matrix interactions in microbes, plants, and animals. Glycosaminoglycan heparin/heparan sulfate binding ability was also detected in Ym1. We report here the three-dimensional structure of Ym1 at 2.5-A resolution by x-ray crystallography. The crystal structure of Ym1 consists of two globular domains, a beta/alpha triose-phosphate isomerase barrel domain and a small alpha + beta folding domain. A notable electron density of sugar is detected in the Ym1 crystal structure. The saccharide is located inside the triose-phosphate isomerase domain at the COOH terminal end of the beta-strands. Both hydrophilic and hydrophobic interactions are noted in the sugar-binding site in Ym1. Despite the fact that Ym1 is not a chitinase, structurally, Ym1 shares significant homology with chitinase A of Serratia marcescens. Ym1 and chitinase A have a similar carbohydrate binding cleft. This study provides new structure information, which will lead to better understanding of the biological significance of Ym1 and its putative gene members.

Use of pulsed-field agarose gel electrophoresis to size genomes of Campylobacter species and to construct a SalI map of Campylobacter jejuni UA580

To determine the physical length of the chromosome of Campylobacter jejuni, the genome was subjected to digestion by a series of restriction endonucleases to produce a small number of large restriction fragments. These fragments were then separated by pulsed-field gel electrophoresis with the contour-clamped homogeneous electric field system. The DNA of C. jejuni, with its low G+C content, was found to have no restriction sites for enzymes NotI and SfiI, which cut a high-G+C regions. Most of the restriction enzymes that were used resulted in DNA fragments that were either too numerous or too small for genome size determination, with the exception of the enzymes SalI (5' ... G decreases TCGAG ... 3'), SmaI (5' .... CCC decreases GGG .... 3'), and KpnI (5' ... GGTAC decreases C .... 3'). With SalI, six restriction fragments with average values of 48.5, 80, 110, 220, 280, and 980 kilobases (kb) were obtained when calibrated with both a lambda DNA ladder and yeast Saccharomyces cerevisiae chromosome markers. The sum of these fragments yielded an average genome size of 1.718 megabases (Mb). With SmaI, nine restriction fragments with average values ranging from 39 to 371 kb, which yielded an average genome size of 1.726 Mb were obtained. With KpnI, 11 restriction fragments with sizes ranging from 35 to 387.5 kb, which yielded an average genome size of 1.717 Mb were obtained. A SalI restriction map was derived by partial digestion of the C. jejuni DNA. The genome sizes of C. laridis, C. coli, and C. fetus were also determined with the contour-clamped homogeneous electric field system by SalI, SmaI, and KpnI digestion. Average genome sizes were found to be 1.714 Mb for C. coli, 1.267 Mb for C. fetus subsp. fetus, and 1.451 Mb for C. laridis.

Genome maps of Campylobacter jejuni and Campylobacter coli

Little information concerning the genome of either Campylobacter jejuni or Campylobacter coli is available. Therefore, we constructed genomic maps of C. jejuni UA580 and C. coli UA417 by using pulsed-field gel electrophoresis. The genome sizes of C. jejuni and C. coli strains are approximately 1.7 Mb, as determined by SalI and SmaI digestion (N. Chang and D. E. Taylor, J. Bacteriol. 172:5211-5217, 1990). The genomes of both species are represented by single circular DNA molecules, and maps were constructed by partial restriction digestion and hybridization of DNA fragments extracted from low-melting-point agarose gels. Homologous DNA probes, encoding the flaAB and 16S rRNA genes, as well as heterologous DNA probes from Escherichia coli, Bacillus subtilis, and Haemophilus influenzae, were used to identify the locations of particular genes. C. jejuni and C. coli contain three copies of the 16S and 23S rRNA genes. However, they are not located together within an operon but show a distinct split in at least two of their three copies. The positions of various housekeeping genes in both C. jejuni UA580 and C. coli UA417 have been determined, and there appears to be some conservation of gene arrangement between the two species.

Methylation of the ribosomal proteins in Escherichia coli. Nature and stoichiometry of the methylated amino acids in 50S ribosomal proteins

Methylated ribosomal proteins from Escherichia coli 50S subunit are localized by growing cells in a medium containing (1-14C)methionine and (3H-methyl)-methionine and comparing the 3H/14C ratio for each of the 50S ribosomal proteins. The following proteins are methylated: L11, L1, L3, L5, L7, L8, L9, L12, L18, and L33. The nature and stoichiometry of the methylated amino acid(s) in each of the methylated proteins are determined. Protein L11 is the most heavily methylated of all the 50S subunit proteins. This protein has previously been implicated in the peptidyl transferase reaction during protein synthesis (K. H. Nierhaus and V. Montejo (1973), Proc. Nat. Acad. Sci. U. S. 47, 1588-1602). Three proteins (L1, L3, and L5) have intermediate levels of methylation and contain about 0.4-0.6 methyl groups each per molecule of protein. Five other proteins (L7, L8, L9, L12, and L18) are also methylated to a slight extent (-0.1 methyl group/molecule of protein). One unknown methylated neutral amino acid was detected in protein L11 and at least one and possibly two other unidentified methylated amino acids appeared to be present in protein L33.

Instantaneous pressure-volume relation of the ejecting canine left atrium

To characterize the pump function of the left atrium, we determined the instantaneous pressure-volume relation of the isolated supported left atrium. A physiologic after-loading system for the low-pressure atrium was created by coupling it to a real-time computer-simulated ventricle and a simulated venous impedance network via a volume servo-pump. In 10 atria loaded with such systems, multiple isochronal sets of pressure-volume data were collected from many ejecting or isovolumic contractions obtained under a constant inotropic state, and the time-varying elastance, E(t), as well as the volume-axis intercepts, VO(t), were calculated. E(t) is the ensemble of slopes, and VO(t), the volume-axis intercepts resulting from the linear regression of instantaneous pressure on instantaneous volume at multiple instants throughout the cardiac cycle. The systolic portion of the left atrial E(t) was insensitive to loading conditions, as was VO(t), which, in addition, proved to be similar to the right atrial and right ventricular VO(t) waveforms in its time dependence. These results indicate that E(t) and VO(t) adequately represent the instantaneous pressure-volume relation of the left atrium in systole irrespective of the mode of contraction. Whatever the underlying mechanism might be, the load insensitivity and similarity of the basic shape of the left atrial E(t) among different atria suggests that the characterization reflects fundamental features of left atrial contraction.

Continuous direct tissue oxygen tension measurement by a new method using an implantable silastic tonometer and oxygen polarography

A new method of tissue oxygen tension measurement that is suitable for human use has been described. An implanted Silastic tube tonometer is combined with polarographic oxygen electrodes. The techniques of preparation, insertion, and measurement have been described. The advantages and disadvantages of this method have been considered in relation to established methods of tissue oxygen tension measurement. The method is suitable for clinical use and can be used to aid clinical decision-making.