Optimization of plasmid maintenance in the attenuated live vector vaccine strain Salmonella typhi CVD 908-htrA

The broad objective of the research presented here is to develop a noncatalytic plasmid maintenance system for the stabilization of multicopy expression plasmids encoding foreign antigens in a Salmonella typhi live-vector vaccine strain such as CVD 908-htrA. We have enhanced the maintenance of expression plasmids at two independent levels. First, we removed dependence upon balanced-lethal maintenance systems that involve catalytic enzymes expressed from multicopy plasmids; we accomplished this through incorporation into expression plasmids of a postsegregational killing system based on the noncatalytic hok-sok plasmid addiction system from the antibiotic resistance factor pR1. We also included at least one naturally occurring plasmid partition function in our expression plasmids, which eliminates random segregation of these plasmids, thereby enhancing their inheritance and stability; to accomplish this, we incorporated either the par locus from pSC101, the parA locus from pR1, or both. We monitored the stability of optimized expression plasmids within CVD 908-htrA by quantitating expression of a variant of green fluorescent protein (GFPuv) by using flow cytometry. In this report, we demonstrate the utility of this novel plasmid maintenance system in enhancing the stability of our expression plasmids and go on to show that as the copy number of stabilized plasmids increases, the toxicity of GFPuv synthesis also increases. The implications of these observations for the rational design of immunogenic and protective bacterial live vector vaccines are discussed.     

Low elementary movement speed is associated with poor motor skill in Turner's syndrome

The article aims to discriminate between 2 features that in principle both may be characteristic of the frequently observed poor motor performance in girls with Turner's syndrome (TS). On the one hand, a reduced movement speed that is independent of variations in spatial accuracy demands and therefore suggests a problem in motor execution. On the other hand, a disproportional slowing down of movement speed under spatial-accuracy demands, indicating a more central problem in motor programming. To assess their motor performance problems, 15 girls with TS (age 9.6-13.0 years) and 14 female controls (age 9.1-13.0 years) were tested using the Movement Assessment Battery for Children (MABC). In additionally, an experimental procedure using a variant of Fitts' graphic aiming task was used to try and disentangle the role of spatial-accuracy demands in different motor task conditions. The results of the MABC reestablish that overall motor performance in girls with TS is poor. The data from the Fitts' task reveal that TS girls move with the same accuracy as their normal peers but show a significantly lower speed independent of task difficulty. We conclude that a problem in motor execution is the main factor determining performance differences between girls with TS and controls.     

Reliability of the acetabular teardrop as a landmark

Summary This study investigated the effect of tilt and observer reliability on radiographic measurements of the position of a prosthetic acetabular cup in seven dry bone pelves using the teardrop as a landmark. Coronal or sagittal tilt of more than five degrees was easily recognisable and there was effectively no observer variation in the measurements up to this limit. In addition, 90 out of 100 randomly selected antero-posterior pelvic radiographs from an outpatient department were not significantly rotated and 93 demonstrated a clearly defined teardrop. Measurements about the teardrop on routine radiographs are therefore sufficiently accurate to allow assessment of prosthetic position.

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La valeur du sourcil cotyloidien comme repère d'analyse radiologique

Résumé Cette étude, conduite sur 7 bassins secs, apprécie l'effet de l'inclinaison du bassin sur la qualité de l'analyse radiographique de la position d'une cupule prothétique de hanche en utilisant le sourcil cotyloïdien comme repère. Une inclinaison du bassin dans les plans coronal et sagittal est aisément détectable et il n'existe pas de variation d'analyse entre les différents observateurs en dessous de 5° d'inclinaison. De plus, sur 100 radiographies antéro-postérieures de bassin choisies au hasard dans les dossiers de consultation, 90 avaient été réalisées sans incidence particulièrement adaptée et l'on pouvait repérer facilement le sourcil sur 93% d'entre elles. Les mesures faites sur des radios de routine sont donc suffisamment précises pour permettre l'évaluation de la position d'une prothèse à partir du sourcil cotyloïdien.

     

The effect of subchronic feeding of 1,1-dichloro-2,2-bis(4'-chlorophenyl)ethene (DDE) on its metabolism in mice

1,1-Dichloro-2, 2-bis(4’-chlorophenyl)ethene (DDE), amajor lipophilic metabolite of 1,1,1-trichloro-2, 2-bis(4'-chloro-phenyDethane(DDT), is a hepatic carcinogen in both the mouse and hamsterupon chronic exposure. DDT is tumori-genic only in the formerspecies. The metabolism in the mouse of [¹⁴C-UL-phenyl]DDE withand without 5-month DDE pretreatment, is reported. The urine,feces and liver were analyzed and in all cases most of the radioactivityobserved was identified as unchanged DDE. The only metaboliteidentified was the phenolic derivative l, l-dichloro-2-(4’-chloro-phenyl)-2-(3"-hydroxy-4"-chlorophenyI)ethene,which was found in significant amounts only in the feces. Noother potential metabolites derived from the oxidation of DDEwere observed. The effect that pretreatment with DDE had onits own metabolism was to decrease the urinary excretion ofDDE and to increase the hepatic levels. It appears from theseresults that any oxidative metabolism of DDE constitutes a veryinsignificant pathway in the mouse. It is also concluded thatthere is no significant change in the metabolism of DDE afterprolonged exposure to the pesticide, and there is no indicationfor the metabolism of DDE to a reactive electrophilic species.     

Osteosarcomatosis

A review of the 690 cases of osteosarcoma in the radiographic file of the Armed Forces Institute of Pathology revealed 29 cases of "osteosarcomatosis" (multiple skeletal sites of osteosarcoma). Fifteen of these patients were 18 years old and under and manifested rapidly appearing, usually symmetric, sclerotic metaphyseal lesions. The remaining 14 patients were more than 18 years old and had fewer, asymmetric sclerotic lesions. In most patients (28 of 29), a radiographically dominant skeletal tumor was seen. Pulmonary metastases occurred in the majority of patients and were detected at the same time as the bone lesions. These 29 patients were studied with regard to demographic data and skeletal distribution and radiographic appearance of their lesions. As a result of the findings, a metastatic origin from a primary dominant osteosarcoma is favored over a multifocal origin as the basis for osteosarcomatosis. Osteosarcomatosis is more commonly encountered in the mature skeleton than has been previously recognized.     

Use of cefazolin for peritonitis treatment in peritoneal dialysis patients

For over two decades, intraperitoneal administration of vancomycin and an aminoglycoside has been an accepted regimen for the empiric treatment of peritonitis in the peritoneal dialysis patient, until definite identification of the organism has been made. The recent emergence of vancomycin-resistant organisms has been of great concern in many centers. The current treatment recommendation therefore is to use cefazolin in place of vancomycin. We analyzed peritonitis data from January 1, 1996 to June 30, 1997, prior to switching over to cefazolin. Seventy-five percent (27 episodes) in 1997 as compared to 78% in 1996 were due to gram-positive organisms. Twenty-two percent (8 episodes) were due to gram- negative organisms in 1997, 21% in 1996, and 3% (1 episode) due to yeast in 1997, 3% in 1996. Staphylococcus epidermidis (SE) caused 33% of the gram-positive peritonitis episodes in 1997 as compared to 37% in 1996. Twenty-two percent of the gram-positive episodes were due to Staphylococcus aureus (SA) in 1997 and 46% in 1996. Enterococcal infections were 26% in 1997 and 1% in 1996. All of these were confined to only 1 patient. The antibiogram revealed 100% sensitivity of both SA and SE to vancomycin and 100% sensitivity of SA to cefazolin, but only 11% sensitivity of SE to cefazolin. The same patient population had a 48% sensitivity of SE to cefazolin in 1996, showing a sudden and substantial increase in resistance to SE. Even though SE is thought to be a less virulent organism, treating patients with a high probability of being infected by SE with an antibiotic showing 89% resistance is not warranted. Copyright Copyright 1999 S. Karger AG, Basel     

Effects of drugs of abuse on acquisition of behavioral chains in squirrel monkeys

The acute effects of various drugs of abuse on the acquisition of chains of behavior were assessed in squirrel monkeys trained to respond on three keys for food. Each new session the monkeys acquired a different four-response chain by responding sequentially on three keys in the presence of four different stimuli. Incorrect responses inactivated the keys and darkened the chamber for 10 s (time-out). Dose-effect curves were obtained by administering the drugs intramuscularly before the session and recording their effects on the rate and accuracy of responding. Cocaine,d-amphetamine, and ⁹-tetrahydrocannabinol all decreased the accuracy and rate of responding within the dose range of 0.56–3 mg/kg. The highest dose of morphine tested (3 mg/kg) produced parallel decreases in the accuracy and rate of responding in some monkeys but had no effect at lower doses. These drugs decreased within-session accuracy though clearly acquisition did occur, but high doses of caffeine (30 and 56 mg/kg) prevented acquisition and recovery of performance and, furthermore, at 30 mg/kg these effects were observed in the absence of decreases in the rate of responding. The drugs of abuse tested all produced dose-related decreases in both the accuracy and rate of responding, and the decreases in accuracy were primarily observed only at doses that also decreased response rates. Therefore, based on these results from nonhuman primates each of these drugs has the potential to alter learning particularly when doses that disrupt other behaviors are administered.