The role of parenteral antischistosomal therapy in the spread of hepatitis C virus in Egypt

BACKGROUND

The population of Egypt has a heavy burden of liver disease, mostly due to chronic infection with hepatitis C virus (HCV). Overall prevalence of antibody to HCV in the general population is around 15-20%. The risk factor for HCV transmission that specifically sets Egypt apart from other countries is a personal history of parenteral antischistosomal therapy (PAT). A review of the Egyptian PAT mass-treatment campaigns, discontinued only in the 1980s, show a very high potential for transmission of blood-borne pathogens. We examine the relative importance of PAT in the spread of HCV in Egypt.

METHODS

The degree of exposure to PAT by cohort was estimated from 1961-86 Ministry of Health data. A cohort-specific exposure index for PAT was calculated and compared with cohort-specific HCV prevalence rates in four regions.

FINDINGS

HCV prevalence was calculated for 8499 Egyptians aged 10-50 years. A significant association between seroprevalence of antibodies to HCV and the exposure index (1.31 [95% CI 1.08-1.59]; p=0.007) was identified across four different regions. In all regions cohort-specific HCV prevalence was lowest in children and young adults than in older cohorts. These lower prevalence rates coincided with the gradual and final replacement of PAT with oral antischistosomal drugs at different points in time in the four regions.

INTERPRETATION

The data suggest that PAT had a major role in the spread of HCV throughout Egypt. This intensive transmission established a large reservoir of chronic HCV infection, responsible for the high prevalence of HCV infection and current high rates of transmission. Egypt's mass campaigns of PAT may represent the world's largest iatrogenic transmission of blood-borne pathogens.

Tendons and ligaments: a morphological and biochemical comparison

The purpose of this study was to compare selected rabbit tendons and ligaments morphologically and biochemically. Five representative structures from each of six age- and sex-matched rabbits were compared. Biochemical analyses included total collagen, reducible collagen cross-links, quantitative collagen typing, DNA, and glycosaminoglycans. Histological and chemical differences were demonstrated between the tendons and the ligaments. Smaller differences were also found between the individual ligaments (collateral and cruciate) and between the two tendons (patellar and Achilles) that were examined. These findings suggest that ligaments are more metabolically active than tendons, having more plump cellular nuclei, higher DNA content, larger amounts of reducible cross-links, and the presence of more type III collagen, as compared with tendons. They also contain slightly less total collagen than tendons and more glycosaminoglycans. We conclude that the tendons and ligaments studied have unique histological and biochemical characteristics, despite their gross similarities. Relatively increased metabolic activity in ligaments, implied by our findings, may be species specific, age related (transient), or may truly represent a structural expression of functional need for more rapid adaptation. Further investigation of other similarities or differences between particular ligaments (or tendons) is indicated, and attention is directed toward the importance of such variables in development of models for tendon and ligament studies.

Medial collateral ligament healing. A multidisciplinary assessment in rabbits

Medial collateral ligament healing without treatment has been studied in a rabbit model. Complete midsubstance gaps were found to heal by distinct scar formation over time. This healing process was fast since the gap was bridged quickly; however, more subtle changes in appearance of the healing tissue continued for many months. The ligament "scar" was found to be structurally abnormal chemically and mechanically even at long-term followup. A plateau in its improvement suggests that the scar may never approach normal ligament characteristics (without treatment). A baseline of ligament healing by scar formation has been established.

Dysphagia following chemoradiation for locally advanced head and neck cancer

BACKGROUND

To assess the prevalence, severity and morbidity of dysphagia following concurrent chemoradiation for head and neck cancer.

PATIENTS AND METHODS

Patients who underwent chemotherapy and radiation for head and neck malignancies were evaluated for their ability to resume oral feeding following treatment. Modified barium swallow (MBS) studies were performed if the patients complained of dysphagia or if there was clinical suspicion of aspiration. The severity of dysphagia was graded on a scale of 1-7. If significant abnormalities were found, swallowing studies were repeated until resolution of dysphagia.

RESULTS

Between March 1999 and May 2002, 55 patients with locally advanced head and neck cancer underwent concurrent chemotherapy and radiation. Aspiration pneumonia was observed in eight patients, three during treatment and five following treatment. Five patients died from pneumonia. Two patients developed respiratory failure requiring intubation as a complication of pneumonia. At a median follow-up of 17 months (range 6-48 months), 25 patients (45%) developed severe dysphagia requiring prolonged tube feedings for more than 3 months (22 patients) or repeated dilatations (three patients). Among 33 patients who underwent MBS following treatment, 12 patients (36%) had silent aspiration (grade 6-7 dysphagia). Thirteen patients (39%) developed grade 4-5 dysphagia which required prolonged enteral nutritional support to supplement their oral intake. Most patients had severe weight loss (0-21 kg) during treatment, likely due in part to mucositis in the orodigestive tube.

CONCLUSIONS

Dysphagia is a common, debilitating and potentially life-threatening sequela of concurrent chemoradiation for head and neck malignancy. Physicians should be aware that the clinical manifestations of aspiration may be unreliable and insidious, because of the depressed cough reflex. Modified and traditional barium swallows should be performed following treatment to assess the safety of oral feeding and the structural integrity of the pharynx and esophagus. Patients with severe dysphagia may benefit from rehabilitation. Tube feeding should be continued for those with aspiration.

Initial study of arthropod succession on pig carrion in a central European urban habitat

We conducted a carrion succession study within a restricted urban backyard in the city of Vienna, Austria (16 degrees 22'E, 48 degrees 12'N) from May to November 2001 to analyze sequence and composition of the local carrion visiting fauna. Two medium sized clothed domestic pig carcasses (Sus scrofa Linnaeus), were used as surrogate human models. In total, 42 arthropod species from the families Calliphoridae, Sarcophagidae, Sepsidae, Piophilidae, Muscidae, Fanniidae, Sphaeroceridae, Phoridae, Drosophilidae, Anthomyiidae, and Lauxaniidae (Diptera), Formicidae, Braconidae, Pteromalidae, and Vespidae (Hymenoptera), Silphidae, Staphylinidae, Histeridae, Cleridae, and Dermestidae (Coleoptera), as well as species from the orders Isopoda and Acari were collected during the decomposition of these carcasses. A significant feature in this study was the high abundance of Calliphora vomitoria (L.) and Chrysomya albiceps (Wiedemann). In the experiment conducted May to June, larvae and adults of C. vomitoria outnumbered all other blow fly species, followed by Protophormia terraenovae (Robineau-Desvoidy), C. vicina Robineau-Desvoidy, and Lucilia sericata (Meigen). C. vomitoria is generally considered to be rural in distribution, where it prefers shaded locations. The presence of this species in rural as well as in urban habitats in Austria precludes this species as biogeographic indicator. In the study beginning in August large numbers of female adults of the nonindigeous blow fly C. albiceps began oviposition at day 3 after placement of the cadaver. The predatory second and third instars of C. albiceps larvae subsequently almost monopolized the cadaver. C. albiceps is generally described as tropical and subtropical species. The observed northward expansion of its range beyond southern Europe obviously decreases the value of C. albiceps in estimating place of death, in that it is no longer exclusive to southern regions. Our results clearly show, that caution must be used when drawing conclusions from succession data generated in different geographic areas. Moreover, this study demonstrates, that arthropod mediated decomposition of a 44 kg exposed pig carcass in a central European urban habitat can be completed within 3 wk.

Water content alters viscoelastic behaviour of the normal adolescent rabbit medial collateral ligament

Testing environment is an important factor in the outcome of mechanical tests on connective tissue. The purpose of this investigation was to determine the effect of ligament water content on ligament mechanical behaviour by altering the test environment. Water content of medial collateral ligament (MCLs) from 19 three-month-old New Zealand White rabbits was varied in subsets of ligaments pairs by means of immersion in 2, 10 or 25% sucrose or 0.9% phosphate-buffered saline (PBS) solutions for 1 h. One knee joint was cycled 50 times in the designated solution (experimental), while the contralateral knee (uncycled control) was simultaneously soaked in the same tank. Following cycling, the water contents of both test and control ligaments were determined. Water contents of 22 normal MCLs were determined immediately post-sacrifice and served as 'normal water content' controls. Normalized peak cyclic load changes were used as a measure of the viscoelastic behaviour of each MCL. Results demonstrated that only ligaments soaked (but not cycled) in a 10% sucrose solution had water contents (60.5 +/- 2.5%) which were statistically similar to the 22 fresh normal MCLs (63.9 +/- 6.0%). Ligaments soaked in PBS (74.0 +/- 1.3%) or 2% sucrose (69.2 +/- 2.3%) had significantly higher water contents compared to fresh normal MCLs. Ligaments with higher water contents (e.g. soaked in PBS or 2% sucrose) demonstrated greater cyclic load relaxation compared to ligaments with lower contents (e.g. soaked in 25 or 10% sucrose). Different fluid test environments can significantly alter ligament water content and, in turn, significantly affect ligament viscoelastic behaviour.

The effect of elastic bandages on human knee proprioception in the uninjured population

Elastic bandages are often used to treat musculoskeletal disorders, even though there is little scientific evidence currently to support this generalized practice. We tested the hypothesis that elastic bandages improve proprioception of the bandaged joint during their use, and that this benefit was more than temporary. The uninjured human knee was used as a model. Fifty-four volunteers (54 knees), aged 22 to 40 years, were asked to identify a prior set joint angle as their knee was passively extended. Each knee was tested without the elastic bandage, immediately after bandage application, after 1 hour of bandage wear, and finally after removal of the bandage. Results showed that elastic bandages significantly improved knee joint proprioception in the uninjured knee during the entire interval of their use (mean decrease in inaccuracy of 1.0 degree, equivalent to 25% improvement, P < 0.05), and that this benefit was lost when the bandage was removed. The magnitude of the improvement, or the potential beneficial effect of the bandage, was inversely related to the participant's inherent knee proprioceptive ability, which was demonstrated in the test group before the initial application of the bandage.

Detection of low copy human papilloma virus DNA and mRNA in routine paraffin sections of cervix by non-isotopic in situ hybridisation

In analysing human papilloma virus (HPV) infection of the cervix in formalin fixed paraffin sections by non-isotopic in situ hybridisation two main problems were found: detachment of sections from the glass during hybridisation and probe detection; inadequate sensitivity and inability to assess sensitivity of the in situ procedure. The first problem was investigated by assessing the efficiency of various tissue adhesives individually and in combination. The second problem was addressed by optimising conditions for DNA unmasking, hybridisation, and biotinylated probe detection. Sensitivity of the final in situ procedure developed was assessed by using the detection of pHY2.1 repeats as a built-in control. Extrapolation of data showed that less than 10 copies of HPV DNA can be visualised by these procedures. HPV nucleic acid, mainly in the form of DNA, was detected not only in koilocytic nuclei but also in suprabasal cells in condylomas and CIN lesions. HPV mRNA was also visualised in the cytoplasm (and probably also nuclei) of the same cell types. These non-isotopic in situ procedures give results comparable to those obtained with radiolabelled probes, but they are less time consuming and provide better morphological resolution.

Noninvasive patient fixation for extracranial stereotactic radiotherapy

PURPOSE

To evaluate the setup accuracy that can be achieved with a novel noninvasive patient fixation technique based on a body cast attached to a recently developed stereotactic body frame during fractionated extracranial stereotactic radiotherapy.

METHODS AND MATERIALS

Thirty-one CT studies (> or = 20 slices, thickness: 3 mm) from 5 patients who were immobilized in a body cast attached to a stereotactic body frame for treatment of paramedullary tumors in the thoracic or lumbar spine were evaluated with respect to setup accuracy. The immobilization device consisted of a custom-made wrap-around body cast that extended from the neck to the thighs and a separate head mask, both made from Scotchcast. Each CT study was performed immediately before or after every second or third actual treatment fraction without repositioning the patient between CT and treatment. The stereotactic localization system was mounted and the isocenter as initially located stereotactically was marked with fiducials for each CT study. Deviation of the treated isocenter as compared to the planned position was measured in all three dimensions.

RESULTS

The immobilization device can be easily handled, attached to and removed from the stereotactic frame and thus enables treatment of multiple patients with the same stereotactic frame each day. Mean patient movements of 1.6 mm+/-1.2 mm (laterolateral [LL]), 1.4 mm+/-1.0 mm (anterior-posterior [AP]), 2.3 mm+/-1.3 mm (transversal vectorial error [VE]) and < slice thickness = 3 mm (craniocaudal [CC]) were recorded for the targets in the thoracic spine and 1.4 mm+/-1.0 mm (LL), 1.2 mm+/-0.7 mm (AP), 1.8 mm+/-1.2 mm (VE), and < 3 mm (CC) for the lumbar spine. The worst case deviation was 3.9 mm for the first patient with the target in the thoracic spine (in the LL direction). Combining those numbers (mean transversal VE for both locations and maximum CC error of 3 mm), the mean three-dimensional vectorial patient movement and thus the mean overall accuracy can be safely estimated to be < or = 3.6 mm.

CONCLUSION

The presented combination of a body cast and head mask system in a rigid stereotactic body frame ensures reliable noninvasive patient fixation for fractionated extracranial stereotactic radiotherapy and may enable dose escalation for less radioresponsive tumors that are near the spinal cord or otherwise critically located while minimizing the risk of late sequelae.

A Revised Diagnostic Classification of Canine Glioma: Towards Validation of the Canine Glioma Patient as a Naturally Occurring Preclinical Model for Human Glioma

The National Cancer Institute-led multidisciplinary Comparative Brain Tumor Consortium (CBTC) convened a glioma pathology board, comprising both veterinarian and physician neuropathologists, and conducted a comprehensive review of 193 cases of canine glioma. The immediate goal was to improve existing glioma classification methods through creation of a histologic atlas of features, thus yielding greater harmonization of phenotypic characterization. The long-term goal was to support future incorporation of clinical outcomes and genomic data into proposed simplified diagnostic schema, so as to further bridge the worlds of veterinary and physician neuropathology and strengthen validity of the dog as a naturally occurring, translationally relevant animal model of human glioma. All cases were morphologically reclassified according to a new schema devised by the entire board, yielding a majority opinion diagnosis of astrocytoma (43, 22.3%), 19 of which were low-grade and 24 high-grade, and oligodendroglioma (134, 69.4%), 35 of which were low-grade and 99 were high-grade. Sixteen cases (8.3%) could not be classified as oligodendroglioma or astrocytoma based on morphology alone and were designated as undefined gliomas. The simplified classification scheme proposed herein provides a tractable means for future addition of molecular data, and also serves to highlight histologic similarities and differences between human and canine glioma.

Production of Shiga-like toxins by Escherichia coli O157:H7 can be influenced by the neuroendocrine hormone norepinephrine

To examine whether the neuroendocrine hormone norepinephrine may influence the production of the Shiga-like toxins (SLTs), several Escherichia coli O157:H7 clinical isolates were grown in the presence or absence of norepinephrine. An in vitro culture system consisting of low (<1500 colony-forming units/ml) initial concentrations of inocula into a serum-based medium was used to more closely approximate in vivo conditions. The growth of all isolates was increased several logs in the presence of norepinephrine, as compared with the growth in controls, during a 24-hour growth period. Controls included additional dextrose as well as the use of the norepinephrine metabolite normetanephrine, which contains one more methyl group than norepinephrine and hence would serve as a better energy source for growth if the effect were solely nutritionally mediated. During the 24 hours of growth, the production of cell-associated SLT-I on a protein-equivalent basis was shown to be increased over 100-fold in norepinephrine-cultured bacteria as compared with controls. SLT-II elaboration into culture supernatants was also greatly increased in norepinephrine-cultured bacteria as compared with controls. Maximal detection of cell-associated SLT-II occurred at least 12 hours before maximum levels were achieved in culture supernatants. Because norepinephrine represents one of the largest pools of monoamines present throughout the small intestine, these results suggest that the neuroendocrine environment of the small intestine may play a role in the growth of O157:H7 and the production of SLTs.

Rabbit medial collateral ligament scar weakness is associated with decreased collagen pyridinoline crosslink density

This study was carried out to quantify the potential associations between material strength and both collagen concentration and pyridinoline collagen crosslink density in the healing medial collateral ligament of the rabbit and to compare these parameters with those of normal ligaments. The right hindlimbs of 24 skeletally mature (12-month-old) New Zealand White rabbits were subjected to a standardized 4 mm midsubstance "gap" injury to the medial collateral ligament. The animals were killed in groups of six at postoperative intervals of 3, 6, 14, or 40 weeks, and the femur-medial collateral ligament-tibia complexes were mechanically tested in tension to failure. Subsequent to mechanical testing, the failure sites of the ligaments were assessed for concentrations of hydroxyproline and hydroxylysyl pyridinoline. Nine additional rabbits served as age-matched normal controls. In healing ligaments, normal collagen concentrations were reached in less than 14 weeks, but the hydroxylysyl pyridinoline crosslink densities remained low and were only 45% of the control values after 40 weeks of healing. Similarly, mechanical values remained much less than the controls. Linear regression analysis of data on scar tissue alone showed a moderately strong positive correlation between hydroxyproline concentration and material strength (r2 = 0.51, p = 0.0001) but no correlation between crosslink density and strength of scar tissue. A similar pattern of correlation was obtained between the elastic modulus of the scar tissue and the biochemical variables, but the r2 values were lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding of phosphatidic acid to the protein-tyrosine phosphatase SHP-1 as a basis for activity modulation

Activation of the SH2 domain-possessing protein-tyrosine phosphatase SHP-1 by acidic phospholipids as phosphatidic acid (PA) has been described earlier and suggested to participate in regulation of SHP-1 activity toward cellular substrates. The mechanism of this activation is poorly understood. Direct binding of phosphatidic acid to recombinant SHP-1 could be demonstrated by measuring the extent of [(14)C]PA binding in a chromatographic assay, by measuring the extent of binding of SHP-1 to PA-coated ELISA plates or silica beads (TRANSIL), and by spectroscopic assays employing fluorescently labeled PA liposomes. In addition to PA, phosphatidylinositol 3,4, 5-trisphosphate (PIP3), dipalmitoylphosphatidylglycerol, phosphatidylinositol 4,5-bisphosphate, and phosphatidylserine (PS) were found to bind to SHP-1, albeit to a lesser extent. A high-affinity binding site for PA and PIP3 was mapped to the 41 C-terminal amino acids of SHP-1. This site was absent from the related protein-tyrosine phosphatase SHP-2 and conferred activation of SHP-1 by PA toward two different substrates at low lipid concentrations. A SHP-1 mutant missing this binding site could, however, still be activated toward phosphorylated myelin basic protein as a substrate at high PA concentrations. This activation is likely to be mediated by a second, low-affinity binding site for PA in the N-terminal part of SHP-1 within the SH2 domains. High-affinity phospholipid binding to the C-terminus of SHP-1 may present a specific mechanism of regulating activity and/or cellular localization.

Natural history of healing in the repaired medial collateral ligament

The purpose of this study was to assess morphologically the healing of repaired medial collateral ligaments (MCLs) in a rabbit model. Healing ligaments were examined grossly and histologically at various intervals, from 3 days to 2 1/2 years after injury, and compared with the appearances of normal age-, sex-, and activity-matched controls. Results show that all ligaments healed by bridging scar formation rather than true ligament regeneration. Increases in cellularity and temporary matrix disorganization along the entire length of the ligaments during healing suggest a combination of diffuse mechanical damage from their failure in tension and regional inflammatory injury (in excess of surgical exposure alone) from the processes of degradation and replacement. Substance that was not injured physically in this model demonstrated complete recovery, while that replaced by scar did not. Healing processes were similar to those of other highly specialized soft tissues (e.g., tendons), with short phases of hemorrhage and inflammation, an intermediate phase of proliferation, and a prolonged phase of remodeling. Failure of repairs to maintain anatomical apposition of torn ends may have contributed to the delay of these healing processes by increasing scar mass. Incomplete scar remodeling at 2 1/2 years, however, suggests much slower MCL healing than previously reported and probably, therefore, a longer period for potential treatment influence.

Large and ongoing outbreak of haemolytic uraemic syndrome, Germany, May 2011

Binary file ES_Abstracts_Final_ECDC.txt matches

Norepinephrine-induced expression of the K99 pilus adhesin of enterotoxigenic Escherichia coli

This study examined whether the provision of norepinephrine, as would be encountered within the highly innervated gastrointestinal system, affected the growth rate of enterotoxigenic Escherichia coli (ETEC) and the expression of the K99 pilus adhesin virulence-related factor. The addition of norepinephrine to serum-containing medium resulted in a 3- to 7-fold increase in the growth rate of the K99+ ETEC strain B44 as compared to growth in vehicle supplemented medium or medium supplemented with normetanephrine, a norepinephrine metabolite that contains one more methyl group than norepinephrine. ELISA analysis revealed that K99 pilus adhesin expression was increased in norepinephrine supplemented culture as compared to normetanephrine and vehicle supplemented controls. This increase occurred from 9 to 15 hours of incubation which represented the exponential growth phase for the norepinephrine supplemented culture. These results indicate that addition of norepinephrine affects both ETEC growth and expression of a specific virulence factor.

Collagen fibril diameters in the healing adult rabbit medial collateral ligament

This study was carried out to test the hypothesis that improvements in ligament scar mechanical behavior during healing may be related, in part, to increases in collagen fibril diameters. Forty-eight adult female New Zealand White rabbits had standardized midsubstance gap injuries created in their right medial collateral ligaments (MCLs) and were allowed normal cage activity until sacrifice in groups of 12 at 3, 6, 14 or 40 weeks post-injury. Eight animals in each group had both MCLs tested biomechanically while 4 animals had transmission EM investigation of midsubstance collagen fibril diameters by a standardized protocol. Results of mechanical tests showed a three- to fourfold increase in scar strength and stiffness over the intervals of healing studied while there was no change in collagen mean fibril minimum diameters. These results demonstrate no correlation between material or structural properties of scar and collagen fibril diameters in this model of healing and suggest that other mechanisms for scar mechanical improvement under these conditions must be investigated.

Two different ionotropic receptors are activated by ATP in rat microglia

1. Our aim was to assess whether ATP-induced inward currents in microglia are due to a single or more than one purinergic receptor. The ATP dose-response curve showed two components, whose presence might be due to the activation of high and low affinity receptors. 2. The P2Z/P2X7 specific receptor agonist benzoylbenzoyl-ATP (Bz-ATP) and some P2 receptor agonists were tested. The rank order of potency was Bz-ATP >> ATP = 2-methylthio-ATP (2-MeSATP) > alpha, beta-methylene ATP (alpha,beta-meATP) >= ADP. beta, gamma-MethyleneATP (beta,gamma-meATP), UTP and adenosine were ineffective. 3. The non-specific P2 receptor antagonist suramin antagonized by 92 +/- 2 % the inward current induced by 100 microM ATP, and by 51 +/- 8 and 68 +/- 6 % those induced by 3 mM ATP and 100 microM Bz-ATP, respectively. The P2Z/P2X7 antagonist oxidized ATP (oATP) almost abolished the inward current induced by 3 mM ATP or Bz-ATP, but was ineffective against 100 microM ATP. 4. Inward currents induced by low ATP concentrations (<= 100 microM) were generally followed by an almost complete and irreversible desensitization, while those elicited by ATP >= 1 mM showed only a partial decline. Interestingly, the inward current induced by 100 microM 2-MeSATP showed a large desensitization, while that induced by Bz-ATP did not. 5. In voltage-ramp experiments, the 100 microM ATP-induced current exhibited a slight inward rectification more visible at negative potentials, while the 3 mM ATP-induced current did not. 6. ATP induced a fast and large increase in [Ca2+] that promptly recovered in the continuous presence of low ATP doses, but did not recover in high ATP doses. As with desensitization, the response to Bz-ATP mimicked that of high doses of ATP. 7. When Ca2+ mobilization due to P2Y receptors was blocked by thapsigargin-induced Ca2+ depletion or by pertussis toxin treatment, 10 microM ATP was still able to induce a Ca2+ transient, which represented the contribution of the Ca2+ influx induced by P2X receptors 8. In conclusion, the inward currents and a fraction of the Ca2+ transients induced by ATP in microglia are due to at least two ATP-sensitive receptor channel types, whose different properties and sensitivity to ATP may be associated with different functional roles.

Dengue virus infection in a traveller returning from Croatia to Germany

Binary file ES_Abstracts_Final_ECDC.txt matches

Collagen fibril diameters in the rabbit medial collateral ligament scar: a longer term assessment

Previous transmission electron microscopic investigations of collagen fibril diameters in rabbit medial collateral ligament (MCL) scars have indicated a homogeneous population of small fibrils for the first 40 weeks of healing. In this study, four 8 mm MCL gap scars were studied at 78 weeks of healing and another three at 104 weeks. Results showed increased heterogeneity in the distribution of fibril diameters in all scars, with the appearance of progressively slightly larger fibrils in 78 and 104 week specimens. All longer term scars still contained roughly 90% small fibrils plus some "patches" of larger fibrils, but there was considerable variation between animals in these proportions. No scar contained the fibril populations typical of uninjured adult rabbit MCLs. These results suggest slow but on-going collagen fibril turnover and remodeling in this gap healing rabbit MCL model via currently unidentified mechanisms.

Functions of the membrane-associated and cytoplasmic malate dehydrogenases in the citric acid cycle of Escherichia coli

Oxidation of malate to oxaloacetate in Escherichia coli can be catalyzed by two enzymes: the well-known NAD-dependent malate dehydrogenase (MDH; EC 1.1.1.37) and the membrane-associated malate:quinone-oxidoreductase (MQO; EC 1.1.99.16), encoded by the gene mqo (previously called yojH). Expression of the mqo gene and, consequently, MQO activity are regulated by carbon and energy source for growth. In batch cultures, MQO activity was highest during exponential growth and decreased sharply after onset of the stationary phase. Experiments with the beta-galactosidase reporter fused to the promoter of the mqo gene indicate that its transcription is regulated by the ArcA-ArcB two-component system. In contrast to earlier reports, MDH did not repress mqo expression. On the contrary, MQO and MDH are active at the same time in E. coli. For Corynebacterium glutamicum, it was found that MQO is the principal enzyme catalyzing the oxidation of malate to oxaloacetate. These observations justified a reinvestigation of the roles of MDH and MQO in the citric acid cycle of E. coli. In this organism, a defined deletion of the mdh gene led to severely decreased rates of growth on several substrates. Deletion of the mqo gene did not produce a distinguishable effect on the growth rate, nor did it affect the fitness of the organism in competition with the wild type. To investigate whether in an mqo mutant the conversion of malate to oxaloacetate could have been taken over by a bypass route via malic enzyme, phosphoenolpyruvate synthase, and phosphenolpyruvate carboxylase, deletion mutants of the malic enzyme genes sfcA and b2463 (coding for EC 1.1.1.38 and EC 1.1.1.40, respectively) and of the phosphoenolpyruvate synthase (EC 2.7.9.2) gene pps were created. They were introduced separately or together with the deletion of mqo. These studies did not reveal a significant role for MQO in malate oxidation in wild-type E. coli. However, comparing growth of the mdh single mutant to that of the double mutant containing mdh and mqo deletions did indicate that MQO partly takes over the function of MDH in an mdh mutant.

Production of an autoinducer of growth by norepinephrine cultured Escherichia coli O157:H7

Escherichia coli O157:H7 were cultured in the presence of norepinephrine to generate conditioned media. The presence of a growth-inducing factor(s) in the conditioned media was examined by measurements of the ability of conditioned media to support the growth of fresh cultures of E coli O157:H7. Supplementation of fresh cultures with as little as 0.024% (v/v) norepinephrine conditioned medium resulted in increased growth as compared to controls, thereby indicating the presence of an autoinducer of growth. Analysis of the production kinetics for the autoinducer during the generation of conditioned media indicates that it differs from other more well characterized autoinducers. It is proposed that the neurohumoral environment of the host may contribute to the production of bacterial growth factors.