Adaptive modeling of the human rib cage in median sternotomy

This paper describes a limited computer-analyzed kinematic model of the rib cage that can be adapted to individual subjects. Also described is its validation and use in assessing the changes in chest wall shape after coronary artery bypass graft (CABG) surgery in 12 patients. The positions of a small number of anatomic locations on the thoracic spine, ribs, manubrium, and sternum are measured from lateral and posterior-anterior chest radiographs. The computer program puts these two views together removing the magnification and reconstructs any missing points to give a three-dimensional picture of the rib cage to which mathematical models of the bones are scaled. The patients had chest radiographs taken at total lung capacity (TLC) and residual volume (RV) to investigate the source of the restrictive ventilatory defect that follows CABG. The predictions from the model were tested by comparing full-sized computer plots with the actual chest radiographs. The estimates of the bony structures were accurate to +/- 3 degrees for orientations and +/- 6 mm for positions. We found reduced rib motion both "pump-handle" (theta) and "bucket handle" (psi) going from theta, psi left, psi right = 9 degrees, 10 degrees, 14 degrees to 4 degrees, 10 degrees, 9 degrees, respectively, after surgery with P less than 0.025, 0.42, 0.07. The angles were measured from the horizontal and increased caudally. There was also reduction in the range of angles subtended by the arc of the thoracic vertebrae between TLC and RV, which went from 12 degrees to -1 degrees (P less than 0.015). These data explain the fall in lung volumes that follow CABG and provide insight into the contribution made by the ribs and spine in full inspiration and full expiration.     

Internal fixation of the sternum in median sternotomy dehiscence.

Sternal dehiscence may be defined as separation of the bony sternum and manubrium following median sternotomy. It may occur at any time postoperatively and has various etiologies. Restoration of sternal integrity in sternal dehiscence is a challenging problem, particularly when associated with deep-seated infection. This report reviews a single-stage technique that virtually eliminates the infected sternotomy wound and provides anatomic reduction and stabilization of the sternum. Complete debridement of infected and/or nonviable soft tissue, bone, and cartilage is followed by pulse irrigation. Parallel stainless steel mandibular reconstruction plates are then placed on each side of the remaining sternum and wired together. One or more transmanubrial compression plates may be added. Bilateral pectoralis major musculocutaneous flap advancement and primary skin closure is performed over two to three closed suction drains. From January of 1994 to July of 1996, this technique was used by the same surgeon in 26 male and 4 female patients aged 43 to 78 years (mean = 61). Indications for the operation were sternal dehiscence with infection (osteomyelitis and/or mediastinitis) in 14 patients and sternal dehiscence without infection in 16 patients. All patients survived to discharge with mean time on the ventilator, intensive care unit length of stay, and postoperative length of stay of 0.7, 2, and 8 days, respectively. Choice and duration of antibiotics were based on culture results and operative findings. Subsequent hardware removal was necessary in one patient for hardware loosening and three patients for late periplate infection. A closed wound was eventually achieved in all 30 patients, and sternal stability was restored in 29 patients. In the management of sternal dehiscence, the described technique of internal fixation can provide anatomic sternal reduction and stabilization, elimination of infection, and wound closure in a single-stage operation. Successful outcomes were achieved despite the presence of severe infection.     

Growth of Paenibacillus larvae,the causative agent of American foulbrood in honey bees and Bacillus popilliae,the causative agent of milky disease in beetle larvae in lepidopteran cell cultures

TNM-FH Lepidopteran insect cell culture medium containing 10% fetal bovine serum (FBS), while allowing limited vegetative growth of Paenibacillus larvae (wild-type strain), the causative agent of American foulbrood, contained no viable vegetative cells upon subculture, nor were any heat resistant spores produced in this medium alone. However, TNM-FH medium cotaining embryonic or midgut cells from Trichoplusia ni, hemocytes from Estigmene acrea, ovarian and embryonic cells from Spodoptera frugiperda, embryonic cells from Plutella xylostella, Spodoptera exigua and Pseudaletia unipuncta or ovarian cells from Lymantria dispar, supported both heavy vegetative cell growth and moderate production of heat resistant spores. EX-CELL 405 serum-free insect cell culture medium alone appeared to contain the appropriate nutrients required for both vegetative growth and sporulation of P. larvae. However, in the presence of embryonic cells from T. ni, limited vegetative growth occurred and the P. larvae cells appeared to die off. This was confirmed by the fact that no colony growth occurred upon subculture, nor were any heat resistant spores detected. This was true also in the presence of fat body cells from T. ni, except that a limited number of spores (4,000/ml) were detected in the form of cology-forming units (CFU) on plates following heating to 80°C for 20 minutes. In a parallel study with a wild-type strain of Bacillus popilliae, vegetative cells grew only in TNM-FH medium in the presence of mid-gut BTI-Tn-MG and ovarian (Tn-368) cells of T. ni. No heat resistant spores, however, were detected in any of the cultures. When BTI-Tn-MG and Tn-368 cells were further challenged with four variant cultures of B. popilliae, vegetative growth and limited sporulation were achieved. The BTI-Tn-MG cell line in TNM-FH medium produced as many as 12,000 spores/ml after 21 days in culture.     

The glycolipids of the causative agent of tularemia]

Up to 10 glycolipids were detected in F. tularensis with the use of thin-layer chromatographic techniques. These glycolipids were slime antigens of F. tularensis membrane. Attenuated F. tularensis strains were found to have defects in their glycolipid composition: in the vaccine strain glycolipid 8 was replaced by more polar lipid 8-a; the avirulent strain had only two glycolipids, and one of them was not typical for virulent strains. Considering that glycolipids differed from entero-bacterial Vi-antigen in their physical-chemical and biological properties, the suggestion was made that the use of the symbol "Vi" to denote the surface substances of F. tularensis should be abolished.     

Capsule formation in the causative agent of glanders

Electron-microscopic and electron-cytochemical method were used to indicate the capability of Pseudomonas mallei (str. N 10230) to produce extracellular slime during the agent growth on the meat-peptone agar. In case of guinea pigs infection the agent forms a capsule that defends the pathogen from phagocytosis.     

Heme catabolism in the causative agent of anthrax

A challenge common to all bacterial pathogens is to acquire nutrients from hostile host environments. Iron is an important cofactor required for essential cellular processes such as DNA repair, energy production and redox balance. Within a mammalian host, most iron is sequestered within heme, which in turn is predominantly bound by hemoglobin. While little is understood about the mechanisms by which bacterial hemophores attain heme from host‐hemoglobin, even less is known about intracellular heme processing. Bacillus anthracis, the causative agent of anthrax, displays a remarkable ability to grow in mammalian hosts. Hypothesizing this pathogen harbors robust ways to catabolize heme, we characterize two new intracellular heme‐binding proteins that are distinct from the previously described IsdG heme monooxygenase. The first of these, HmoA, binds and degrades heme, is necessary for heme detoxification and facilitates growth on heme iron sources. The second protein, HmoB, binds and degrades heme too, but is not necessary for heme utilization or virulence. The loss of both HmoA and IsdG renders B. anthracis incapable of causing anthrax disease. The additional loss of HmoB in this background increases clearance of bacilli in lungs, which is consistent with this protein being important for survival in alveolar macrophages.     

Protein phosphorylation in the causative agent of plague

The phenomenon of the reversible phosphorylation of proteins has been discovered in Y. pestis cells. Eight proteins with a molecular weight of 30-80 kilodaltons have been found capable of phosphorylation. The intensity of phosphorylation has been found to be influenced by the temperature of cultivation and the composition of the incubation medium. This newly found phenomenon of the chemical modification of proteins is supposed to play a certain role in the organization of rapid responses of the cell to changes in the environment.     

The parasitism characteristics of the causative agent of melioidosis in the host cells]

The electron microscopic study of the damaged areas of the lungs, liver, spleen and lymph nodes of guinea pigs infected with two P. pseudomallei virulent strains C-141 and 100 has revealed that this organism is a facultative intracellular parasite and exhibits tropism to reticuloendothelial cells of the body, parasitizing both in "professional" phagocytes (mononuclear, phagocytes, polymorphonuclear leukocytes) and "nonprofessional" phagocytes (capillary endotheliocytes, splenic and lymph-node reticulocytes). In the course of their intracellular development P. pseudomallei have been shown to form capsules protecting the pathogens from the unfavorable action of the protective mechanisms of the host cells.     

Circulation of the causative agent of diphtheria in immune collectives

Prolonged observations on the spread of toxigenic C. diphtheriae carriership, made during a school year in 12 groups of immune children (3809 children), showed that the penetration of diphtherial infection could give rise to the outbreak of bacterial carriership, its level being as high as 20.9-35.1% of the total number of children in the group. The spread of bacterial carriership occurred during the first months after the penetration of the infection, achieving its peak, then followed the subsidence of the infection in the focus. Though some children in the group persistently released C. diphtheriae, almost no new cases of carriership were registered in spring. The highest spread of carriership (55.6-73%) was revealed in the first forms of boarding schools despite a higher level of antitoxic immunity in these children. Cases of the spontaneous cessation of carriership were observed. The spread and subsidence of carriership were determined by the presence or absence of a susceptible contingent. Tests on guinea pigs, carried out in the course of this study to determine the toxigenicity of C. diphtheriae, showed its variability.     

The taxonomic aspects of the transmission of the causative agent of Lyme disease

According to world literature data 17 species of ixodid ticks have been studied for natural infection with the Lyme disease agent. Analysis of the data on the level of the infection, transovarial and transphase transmission has shown that main biological vectors of Borrelia burgdorferi are the species of the subgenus Ixodes s. str. - I. ricinus, I. persulcatus (Eurasia), I. dammini, I. pacificus (North America). Potential vectors are I. scapularis, I. dentatus, Amblyomma americanum, Dermacentor variabilis. Single isolations were registered for I. neotomae, Haemaphysalis leporispalustris, D. occidentalis. Nonidentified spirocheta was isolated from A. americanum, D. variabilis, D. parumapertum, Rhipicephalus sanguineus. No agent was isolated from I. cookey, D. albipictus, R. reticulatus, H. concinna. On the basis of comparative and ontogenetic data the species from a group of main vectors: I. ricinus, I. persulcatus, I. pacificus had been attributed by me to the phyletic group persulcatus before Lyme disease was discovered and its causative agent isolated. The question whether I. scapularis belongs to the group persulcatus was also discussed at that time but left open due to somewhat aberrant structure of gnathosoma at preimaginal phases (Filippova, 1969, 1971, 1973). 6 Palaearctic, 2 Indomalayan and 3 Nearctic species were referred to the group persulcatus at the time. I. dammini was described later, in 1979. Gnathosoma of its preimaginal phases has an intermediate structure between I. scapularis and other species of the group persulcatus. Sexually mature phase and nymph of I. dentatus have much in common with Palaearctic members of the group, I. pavlovskyi, I. kazakstani, I. kashmicus. Preimaginal phases of I. scapularis and nymph of I. dentatus were studied by me on the collection material. Thus, it is possible to speak of the belonging of main vectors of B. burgdorferi to a common phyletic group within the subgenus Ixodes s. str. and, therefore, of common origin of ecological medium for the agent. At the same time each species of the vector is an evolutionally developed difference of ecological medium for B. burgdorferi. Roots of the group persulcatus could originate as far as in Paleocene before the land connection between North America and Europe disappeared. Conditions for the existence of recent species, however, appeared considerably later and their flourishing is dated by Pliocene. The main epidemiological role belongs now to I. ricinus, I. persulcatus, I. dammini, I. pacificus.(ABSTRACT TRUNCATED AT 400 WORDS)     

Proteomics analysis of the causative agent of typhoid fever

Typhoid fever is a potentially fatal disease caused by the bacterial pathogen Salmonella enterica serotype Typhi ( S. typhi). S. typhi infection is a complex process that involves numerous bacterially encoded virulence determinants, and these are thought to confer both stringent human host specificity and a high mortality rate. In the present study, we used a liquid chromatography-mass spectrometry (LC-MS)-based proteomics strategy to investigate the proteome of logarithmic, stationary phase, and low pH/low magnesium (MgM) S. typhi cultures. This represents the first large-scale comprehensive characterization of the S. typhi proteome. Our analysis identified a total of 2066 S. typhi proteins. In an effort to identify putative S. typhi-specific virulence factors, we then compared our S. typhi results to those obtained in a previously published study of the S. typhimurium proteome under similar conditions ( Adkins, J. N. et al. Mol. Cell. Proteomics 2006, 5, 1450-1461 ). Comparative proteomics analysis of S. typhi strain Ty2 and S. typhimurium strain LT2 revealed a subset of highly expressed proteins unique to S. typhi that were exclusively detected under conditions that are thought to mimic the infective state in macrophage cells. These proteins included CdtB, HlyE, and gene products of t0142, t1108, t1109, t1476, and t1602. The differential expression of T1108, T1476, and HlyE was confirmed by Western blot analysis. When our observations are taken together with the current literature, they suggest that this subset of proteins may play a role in S. typhi pathogenesis and human host specificity.