Complete genome sequence of Salmonella enterica serovar Typhimurium LT2

Salmonella enterica subspecies I, serovar Typhimurium (S. typhimurium), is a leading cause of human gastroenteritis, and is used as a mouse model of human typhoid fever. The incidence of non-typhoid salmonellosis is increasing worldwide, causing millions of infections and many deaths in the human population each year. Here we sequenced the 4,857-kilobase (kb) chromosome and 94-kb virulence plasmid of S. typhimurium strain LT2. The distribution of close homologues of S. typhimurium LT2 genes in eight related enterobacteria was determined using previously completed genomes of three related bacteria, sample sequencing of both S. enterica serovar Paratyphi A (S. paratyphi A) and Klebsiella pneumoniae, and hybridization of three unsequenced genomes to a microarray of S. typhimurium LT2 genes. Lateral transfer of genes is frequent, with 11% of the S. typhimurium LT2 genes missing from S. enterica serovar Typhi (S. typhi), and 29% missing from Escherichia coli K12. The 352 gene homologues of S. typhimurium LT2 confined to subspecies I of S. enterica-containing most mammalian and bird pathogens-are useful for studies of epidemiology, host specificity and pathogenesis. Most of these homologues were previously unknown, and 50 may be exported to the periplasm or outer membrane, rendering them accessible as therapeutic or vaccine targets.

Synthesis, characterization, applications, and challenges of iron oxide nanoparticles

Recently, iron oxide nanoparticles (NPs) have attracted much consideration due to their unique properties, such as superparamagnetism, surface-to-volume ratio, greater surface area, and easy separation methodology. Various physical, chemical, and biological methods have been adopted to synthesize magnetic NPs with suitable surface chemistry. This review summarizes the methods for the preparation of iron oxide NPs, size and morphology control, and magnetic properties with recent bioengineering, commercial, and industrial applications. Iron oxides exhibit great potential in the fields of life sciences such as biomedicine, agriculture, and environment. Nontoxic conduct and biocompatible applications of magnetic NPs can be enriched further by special surface coating with organic or inorganic molecules, including surfactants, drugs, proteins, starches, enzymes, antibodies, nucleotides, nonionic detergents, and polyelectrolytes. Magnetic NPs can also be directed to an organ, tissue, or tumor using an external magnetic field for hyperthermic treatment of patients. Keeping in mind the current interest in iron NPs, this review is designed to report recent information from synthesis to characterization, and applications of iron NPs.

Sequence and analysis of chromosome 4 of the plant Arabidopsis thaliana

The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins.

Trauma outcome improves following the advanced trauma life support program in a developing country

Trauma outcome variables before and after the institution of the Advanced Trauma Life Support (ATLS) program were compared for the largest hospital in Trinidad and Tobago from July 1981 through December 1985 (pre-ATLS) and from January 1986 to June 1990 (post-ATLS). A total of 199 physicians were ATLS trained by June 1990. Outcome data were analyzed for all dead or severely injured patients (ISS > or = 16; n = 413 pre-ATLS and n = 400 post-ATLS). Trauma mortality decreased post-ATLS (134 of 400 vs. 279 of 413) throughout the hospital, including the ICU (13.6% post-ATLS ICU mortality vs. 55.2% pre-ATLS). The odds of dying from trauma increased with age (1.02 for each year), ISS score (1.24 for each ISS increment), and blunt injury, both pre-ATLS and post-ATLS. Post-ATLS mortality was associated with a higher ISS (31.6 vs. 28.8). Although there was a higher percentage of blunt injury pre-ATLS (84.0%) versus post-ATLS (68.3%), the mortality rates for both blunt and penetrating injuries were higher in the pre-ATLS group (19.7% pre-ATLS vs. 6.3% post-ATLS for penetrating and 76.6% pre-ATLS versus 46.2% post-ATLS for blunt). For each ISS category, mortality was greater in the pre-ATLS group (ISS > or = 24 pre-ATLS mortality 47.9% vs. 16.7% post-ATLS; ISS 25-40 pre-ATLS mortality 91.0% vs. 71.0% post-ATLS). The overall ratio of observed to expected mortality based on the MTOS data base was lower for the post-ATLS period (pre-ATLS ratio 3.16; post-ATLS ratio 1.94).(ABSTRACT TRUNCATED AT 250 WORDS)

Soluble domain 1 of platelet-endothelial cell adhesion molecule (PECAM) is sufficient to block transendothelial migration in vitro and in vivo

The inflammatory response involves sequential adhesive interactions between cell adhesion molecules of leukocytes and the endothelium. Unlike the several adhesive steps that precede it, transendothelial migration (diapedesis), the step in which leukocytes migrate between apposed endothelial cells, appears to involve primarily one adhesion molecule, platelet-endothelial cell adhesion molecule (PECAM, CD31). Therefore, we have focused on PECAM as a target for antiinflammatory therapy. We demonstrate that soluble chimeras made of the entire extracellular portion of PECAM, or of only the first immunoglobulin domain of PECAM, fused to the Fc portion of IgG, block diapedesis in vitro and in vivo. Furthermore, the truncated form of the PECAM-IgG chimera does not bind stably to its cellular ligand. This raises the possibility of selective anti-PECAM therapies that would not have the untoward opsonic or cell-activating properties of antibodies directed against PECAM.

Design of vitrification solutions for the cryopreservation of embryos

A series of experiments was performed to determine the concentrations at which ten cryoprotectants singly and in pairs would vitrify on plunging into liquid nitrogen and remain vitreous when warmed by plunging into a water bath at 25 degrees C. From these tests eight solutions (VS) were selected for testing of toxicity to mouse morulae in vitro. One of these (VS1) was modified as a further five VS of which one (VS11) was tested for toxicity to all stages of mouse embryos and to sheep compacted morulae. The concentrations at which the cryoprotectants vitrified on cooling were: butylene glycol, 3.0 mol l-1; propylene glycol, 4.0 mol l-1; dimethyl sulfoxide (DMSO) and glycerol 5.0 mol l-1; ethylene glycol, 6.5 mol l-1. None of these, at the highest concentration tested, remained vitreous during warming. Methanol and the high molecular weight polymers, dextran, Ficoll, polyethylene glycol and polyvinylpyrrolidone, did not vitrify at the concentrations tested. Toxicity studies showed the order of increasing toxicity to be ethylene glycol, methanol, DMSO, glycerol, propylene glycol and butylene glycol. Of the mixtures composed of two cryoprotectants, those containing ethylene glycol and glycerol were the least toxic at vitrifying concentrations. VS11 (6.0 mol ethylene glycol l-1 and 1.8 mol glycerol l-1) was well tolerated by mouse morulae, less well by eight- and one-cell embryos and poorly by two-cell embryos. Dilution of the VS11 from mouse embryos by exposure to 1.0 mol sucrose l-1 for 10 min did not enhance their survival.(ABSTRACT TRUNCATED AT 250 WORDS)

How does positive end-expiratory pressure reduce intrapulmonary shunt in canine pulmonary edema?

We ventilated separately the right and left lungs of seven dogs having thoracotomies and catheters in both lower lobe veins. Two hours after right atrial injection of oleic acid, shunt (Qs/QT) in each lower lobe increased from 0.10 to 0.47. Ten minutes after positive end-expiratory pressure (PEEP) was increased from 3 to 13 cmH2O in one lung, mean lobar Qs/QT decreased to 0.06 with no change in its fraction of pulmonary blood flow measured by microsphere techniques. At the same time mean Qs/QT in the other lower lobe was 0.48. At end expiration each lower lobe hilum was then clamped, and the excised lobe was quickly frozen over liquid N2. There was no difference in the extravascular lung liquid per gram blood-free dry lobe between the lower lobes (7.5 +/- 2.6 ml/g), but perivascular cuff liquid was greater in the lower lobe with PEEP (3.8 +/- 2.8 ml/g) than in the lower lobes without PEEP (2.4 +/- 1.7 ml/g). Light microscopy revealed that 77.8 +/- 9.0% of the alveoli were flooded in the lobe without PEEP, but only 22.2 +/- 11.8% were flooded in the lobe with PEEP. The mean linear intercepts of the flooded alveoli were not different between lower lobes, and both were reduced to about 50% of the size of adjacent unflooded units in the same lobe. Alveolar septum thickness was greater without PEEP. We conclude that PEEP reduces Qs/QT by inflating previously flooded and collapsed air spaces and by redistributing the excess alveolar water into the compliant perivascular space, thus eliminating the obstacle to pulmonary O2 transfer.

Behavioral thermoregulatory responses of single- and group-housed mice

The ambient temperature (Ta) to house and study laboratory rodents is critical for nearly all biomedical studies. The ideal Ta for housing rodents and other animals should be based on their thermoregulatory requirements. However, fundamental information on the behavioral thermoregulatory responses of single- and group-housed rodents is meager. To address this issue, thermoregulatory behavior was assessed in individual and groups of CD-1 mice housed in a temperature gradient. Mice were housed in groups of five or individually while selected Ta and motor activity were monitored. Single- and group-housed mice displayed a circadian oscillation of selected Ta and motor activity with relatively warm T(a)s of approximately 29 degrees C selected during the light phase; during the dark phase selected Ta was reduced by 4 degrees C, whereas motor activity increased. Selected Ta of aged (11 months old) mice housed individually was approximately 1.0 degrees C warmer than the group-housed mice. Thermal preference of younger mice (2 months old) was similar for single- and group-housed animals. The operative Ta of mice housed in standard facilities was estimated by measuring the cooling rate of "phantom" mice modeled from aluminum cylinders. The results show that the typical housing conditions for single- and group-housed mice are cooler than their Ta for ideal thermal comfort.

Stability-indicating HPTLC determination of curcumin in bulk drug and pharmaceutical formulations

A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of curcumin both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60 F-254 as the stationary phase. The solvent system consisted of chloroform:methanol (9.25:0.75 v/v). This system was found to give compact spots for curcumin (R(f) value of 0.48 +/- 0.02). Densitometric analysis of curcumin was carried out in the absorbance mode at 430 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r = 0.996 and 0.994 with respect to peak height and peak area, respectively, in the concentration range 50-300 ng per spot. The mean value +/- S.D. of slope and intercept were 1.08 +/- 0.01, 51.93 +/- 0.54 and 8.39 +/- 0.21, 311.55 +/ -3.23 with respect to peak height and area, respectively. The method was validated for precision, recovery and robustness. The limits of detection and quantitation were 8 and 25 ng per spot, respectively. Curcumin was subjected to acid and alkali hydrolysis, oxidation and photodegradation. The drug undergoes degradation under acidic, basic, light and oxidation conditions. This indicates that the drug is susceptible to acid, base hydrolysis, oxidation and photo oxidation. Statistical analysis proves that the method is repeatable, selective and accurate for the estimation of said drug. As the method could effectively separate the drug from its degradation product, it can be employed as a stability-indicating one.

Multiinstitutional experience with the management of superior mesenteric artery injuries

BACKGROUND

Superior mesenteric artery (SMA) injuries are rare and often lethal injuries incurring very high morbidity and mortality. The purposes of this study are to review a multiinstitutional experience with these injuries; to analyze Fullen's classification based on anatomic zone and ischemia grade for its predictive value; to correlate the American Association for the Surgery of Trauma-Organ Injury Scale (AAST-OIS) for abdominal vascular injury with mortality; and to identify independent risk factors predictive of mortality, describing current trends for the management of this injury in America.

DESIGN

We performed a retrospective multiinstitutional study of patients sustaining SMA injuries involving 34 trauma centers in the US over 10 years. Outcomes variables, both continuous and dichotomous, were analyzed initially with univariate methods. For the subsequent multivariate analysis, stepwise logistic regression was used to identify a set of risk factors significantly associated with mortality.

RESULTS

There were 250 patients enrolled, with a mean Revised Trauma Score (RTS) of 6.44 and a mean Injury Severity Score (ISS) of 25. Surgical management consisted of ligation in 175 of 244 patients (72%), primary [corrected] repair in 53 of 244 patients (22%), autogenous grafts were used in 10 of 244 (4%), and prosthetic grafts of PTFE in 6 of 244 patients (2%). Overall mortality was 97 of 250 patients (39%). Mortality versus Fullen's zones: zone I, 39 of 51 (76.5%); zone II, 15 of 34 (44.1%); zone III, 11 of 40 (27.5%); and zone IV, 25 of 108 (23.1%). Mortality versus Fullen's ischemia grade: grade 1, 22 of 34 (64.7%). Mortality versus AAST-OIS for abdominal vascular injury: grade I, 9 of 55 (16.4%); grade II, 13 of 51 (25.5%); grade III, 8 of 20 (40%); grade IV, 37 of 69 (53.6%); and grade V, 17 of 19 (89.5%). Logistic regression analysis identified as independent risk factors for mortality the following: transfusion of greater than 10 units of packed RBCs, intraoperative acidosis, dysrhythmias, injury to Fullen's zone I or II, and multisystem organ failure.

CONCLUSION

SMA injuries are highly lethal. Fullen's anatomic zones, ischemia grade, and AAST-OIS abdominal vascular injuries correlate well with mortality. Injuries to Fullen's zones I and II, Fullen's maximal ischemia grade, and AAST-OIS injury grades IV and V, high-intraoperative transfusion requirements, and presence of acidosis and disrhythmias are significant predictors of mortality. All of these predictive factors for mortality must be taken into account in the surgical management of these injuries.

Predictors of fetal mortality in pregnant trauma patients

BACKGROUND

Fetal mortality after trauma is significant. This study was aimed at identifying factors responsible for this high fetal mortality.

METHODS

All pregnant trauma patients admitted to the two major Toronto trauma institutions during the period of November of 1991 to February of 1996 with an Injury Severity Score (ISS) > or = 12 were assessed. Data on age, gestation, hypotension, ISS, hemoglobin, blood transfusion, length of stay, disseminated intravascular coagulation (DIC), and specific maternal injury were analyzed retrospectively to determine predictors of fetal mortality by comparison of patients with and without fetal survival.

RESULTS

Twenty of a total of 68 pregnant trauma patients qualified for entry into the trauma registry by having an ISS > or = 12. Overall fetal mortality was 65% (13 of 20) for ISS > or = 12, and there was one maternal death (age, 29 years; ISS, 66). There were no statistically significant differences between the fetal death and fetal survival groups in age (29.2 +/- 6.2 vs. 30.4 +/- 3.9 years), gestation (25.3 +/- 10.5 vs. 24.1 +/- 9.2 weeks), lowest systolic blood pressure (98.3 +/- 33.8 vs. 112 +/- 18.0 mm Hg), head injury rate (3 of 13 vs. 1 of 7), extremity injury rate (8 of 13 vs. 2 of 7), abdominal injury rate (4 of 13 vs. 0 of 7), pelvic fracture rate (6 of 13 vs. 1 of 7), and chest injury rate (5 of 13 vs. 3 of 7). However, ISS (27.7 +/- 3.5 vs. 14.2 +/- 11.4), lowest hemoglobin level (78.8 +/- 17.0 vs. 101.9 +/- 17.1), blood transfusions (10.8 +/- 6.3 vs. 0.9 +/- 1.6 units), length of stay (20.9 +/- 16.7 vs. 8.2 +/- 4.9 days), and the incidence of DIC (8 of 13 vs. 0 of 7) were statistically significantly different between the two groups (p < 0.05). All eight patients with abruptio placentae had associated fetal mortality.

CONCLUSIONS

Apart from ISS, blood loss, and abruptio placentae; the presence of DIC was the most significant predictor of fetal mortality. This finding may represent stimulation of DIC by placental products entering the maternal circulation after significant intrauterine injury.

Advanced trauma life support program increases emergency room application of trauma resuscitative procedures in a developing country

Over a 9-year period (July 1981-December 1985--pre-ATLS period; January 1986-June 1990--post-ATLS period), the hospital charts of 813 trauma patients with ISS > or = 16 were reviewed (n = 413, pre-ATLS and n = 400, post-ATLS) in order to assess the impact of the ATLS program. The frequency of endotracheal intubation (ET), nasogastric tube insertion (NG), intravenous access (i.v.), Foley catheterization of the bladder (Foley) and chest tube insertion (CT) were compared by Pearson Chi-square analysis. Overall, pre-ATLS vs. post-ATLS frequencies (%) were 83.5 vs. 65.3 for ET, 97.3 vs. 98.0 for i.v., 74.6 vs. 96.3 for Foley, 68.3 vs. 91.3 for NG, and 18.4 vs. 47.0 for CT. In the emergency room these frequencies (%) were 26.1 vs. 36.4 for ET, 98.8 vs. 98.7 for i.v., 11.0 vs. 97.1 for Foley, 3.2 vs. 95.9 for NG, and 3.9 vs. 95.2 for CT. The differences in the application of these life saving procedures between the pre-ATLS and post-ATLS periods were statistically significant (p < 0.05) except i.v. access, which showed no difference between the pre-ATLS and post-ATLS groups. Of the patients with severe chest injuries (AIS > or = 3) 87.7% had chest tubes post ATLS (94.4% in ER) compared with 48.1% pre ATLS (3.2% in ER). These differences were associated with significant improvement in trauma patient outcome post ATLS. We conclude that the frequency of lifesaving interventions, particularly in the ER, was increased post ATLS.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of the Advanced Trauma Life Support program on medical students' performance in simulated trauma patient management

BACKGROUND

Part of the senior medical students' examination at the University of Toronto involves testing with simulated patient management. We compared the performance in these simulations of senior medical students who received Advanced Trauma Life Support (ATLS) training with those who did not receive ATLS training.

METHODS

Thirty-two students (group I) completed a standard ATLS course, 12 students (group II) audited the ATLS course, and their performance in the trauma simulations was compared with 44 matched control students (group III) from the same class. Performance in the nontrauma patient simulation stations was also analyzed. The score on each station was standardized to a maximum of 20. The students were also graded on overall Approach (scale of 1 to 5) and pass status.

RESULTS

The mean scores (+/-SD, *p < 0.05 compared with other groups) were as follows: Trauma Station, 17.5 +/- 1.02* for group I, 11.76 +/- 0.72* for group II, and 14.67 +/- 0.54* for group III; Nontrauma Station, 13.05 +/- 0.95 for group I, 12.25 +/- 0.72 for group II, and 11.88 +/- 0.80 for group III; Approach, 4.45 +/- 0.50* for group I, 2.09 +/- 0.60* for group II, 3.50 +/- 0.67* for group III. The ATLS-trained and ATLS-audit students had higher scores in the trauma stations than the control group, with the highest scores being in the ATLS-trained group. All ATLS-trained students passed with 62.5% honors and 37.5% passing grades. The ATLS-audit group had 33.3% honors and 66.6% passing grades, compared with the control group who had 84.09% pass, 9.09% borderline, and 6.82% failure in the trauma stations.

CONCLUSIONS

The ATLS course, both complete and audit status, prepares students more appropriately for managing trauma patients as judged by trauma simulation scenarios. Consideration should be given for including ATLS as an integral part of the senior medical student curriculum.

Trauma patient outcome after the Prehospital Trauma Life Support program

BACKGROUND

We have previously demonstrated a significant improvement in trauma patient outcome after the Advanced Trauma Life Support (ATLS) program in Trinidad and Tobago. In January of 1992, a Prehospital Trauma Life Support (PHTLS) program was also instituted. This study assessed trauma patient outcome after the PHTLS program.

METHODS

Morbidity (length of stay and degree of disability), mortality, injury severity score, mechanism of injury, age, and sex among all adult trauma patients transported by ambulance to the major trauma hospital were assessed between July of 1990 to December of 1991 (pre-PHTLS, n = 332) and January of 1994 to June of 1995 (post-PHTLS, n = 350).

RESULTS

Age, sex distribution, percentage blunt injury, and injury severity score were similar for both groups. Mortality pre-PHTLS (15.7%) was greater than post-PHTLS (10.6%). Length of stay and disability were statistically significantly decreased post-PHTLS. Age, injury severity score, and mechanism of injury were positively correlated with mortality in both periods. The previously reported post-ATLS mortality was similar to the pre-PHTLS mortality.

CONCLUSIONS

Post-PHTLS mortality and morbidity were significantly decreased, suggesting a positive impact of the PHTLS program on trauma patient outcome.

Molecular diversity and multilocus organization of the parental lines used in the International Rice Molecular Breeding Program

One hundred and ninety three parental lines obtained from 26 countries for an international rice molecular breeding program were evaluated using 101 well-distributed simple sequence repeat (SSR) markers. An overall genetic diversity of 0.68 and an average of 6.3 alleles per locus were revealed, indicating a high level of genetic variation in these lines. Cluster analysis of the 193 accessions showed three major groups and nine subgroups. Group I corresponded to the classical indica subspecies, whereas groups II and III belong to the japonica subspecies. Indica and japonica differentiation accounted for only 6.5% of the total variation in the entire sample and 93.5% was due to within-subspecies diversity. Differentiation among eco-geographic regions accounted for 24% of the diversity within the subspecies. Larger amounts of the eco-geographical differentiation were resolved within japonica than within indica. The largest indica-japonica differentiation based on the single locus level was detected by markers on chromosomes 9 and 12, while the smallest differentiation was detected by markers on chromosomes 4 and 8. Furthermore, genetic differences at the single-locus and two-locus levels, as well as components due to allelic and gametic differentiation, were revealed between indica and japonica and among the main geographic regions. The multilocus analysis in genetic diversity showed a higher proportion of variation caused by predominant non-random associations of different loci within and among the classified subspecies and geographic subdivisions. The results suggest that selection for eco-geographical adaptation on multilocus associations was largely responsible for the maintenance of the extensive variation in the primary gene pool of rice.

Effect of furosemide in canine low-pressure pulmonary edema

We studied the effect of furosemide on pulmonary oxygen exchange, lung liquid, and central hemodynamics in dogs with pulmonary capillary leak induced by intravenous oleic acid (OA). 2 h after OA, triple indicator-dilution lung liquid volume and pulmonary shunt (Qs/Qt) doubled despite normal pulmonary capillary wedge pressure in 16 dogs compared with dogs not given OA in which no variable change during the same time. Six edematous dogs were then treated with furosemide (1 mg/kg), and 2 h later they showed significant reductions in Qs/Qt and lung liquid. In contrast, six other edematous dogs not given furosemide increased Qs/Qt and lung liquid during the same time. The changes in edema after furosemide could not be attributed to altered wedge or colloid osmotic pressures, and similar changes in Qs/Qt and lung liquid with furosemide were observed in four nephrectomized dogs. We conclude that pulmonary vasoactive effects of furosemide account for reduced shunt and edema in canine pulmonary capillary leak. These effects of furosemide differ from those in cardiogenic pulmonary edema, and suggest a different rationale for diuretic therapy in low-pressure pulmonary edema. Analysis of count rates from 51Cr-labeled erythrocytes and 125I-labeled albumin in lungs excised from 12 dogs indicated that the composition of excess lung liquid did not change with furosemide, and was 50% plasma, 25% blood, and 25% crystalloid.

Attrition of cognitive and trauma management skills after the Advanced Trauma Life Support (ATLS) course

OBJECTIVE

To test the attrition of cognitive and trauma management skills among practising physicians after the Advanced Trauma Life Support (ATLS) course.

DESIGN, MATERIALS, AND METHODS

Sixty practising physicians who completed the ATLS course had comparative assessment of cognitive skills (with multiple choice questions, MCQ) pre-ATLS, immediately post-ATLS, at 6 months (group A), 2 years (group B), 4 years (group C), and 6 years (group D) after the course. Trauma management skills were also compared using eight Objective Structured Clinical Examination (OSCE) trauma stations completed by the four groups of physicians.

MEASUREMENTS AND MAIN RESULTS

Pre-ATLS MCQ scores (54.2 +/- 4.2 to 59.8 +/- 5.3%) and immediately post-ATLS MCQ scores (85.9 +/- 5.1 to 87.7 +/- 5.3%) were similar in all four groups. Follow-up MCQ scores were 77.8 +/- 3.6% at 6 months 70.6. +/- 1.9% at 2 years, 69.4 +/- 1.7% at 4 years, and 68.9 +/- 2.0% at 6 years. OSCE scores out of a maximum of 20 were 16.8 +/- 0.3 at 6 months, 13.9 +/- 0.1 at 2 years, 12.0 +/- 0.1 at 4 years, and 11.9 +/- 0.1 at 6 years. Adherence-to-priorities scores (maximum, 7) were 6.6 +/- 0.2 at 6 months, 6.8 +/- 0.1 at 2 years, 6.6 +/- 0.1 at 4 years, and 6.6 +/- 0.1 at 6 years. Organized-approach scores (maximum, 5) were 4.8 +/- 0.1 at 6 months, 4.6 +/- 0.2 at 2 years, 4.7 +/- 0.2 at 4 years, and 4.6 +/- 0.2 at 6 years. Using the MCQ 80% pass mark criterion, at least 50% of physicians fail by 6 months and all fail this cognitive test thereafter.

CONCLUSIONS

Whereas cognitive and trauma management skills decline after the ATLS, these skills are maintained at similar levels between 4 and 6 years after ATLS. A 50% failure rate occurs within 6 months and maximum attrition of cognitive skills occurs within 2 years of ATLS completion. Major principles of adherence to priorities and maintenance of an organized approach to trauma care are preserved for at least 6 years after ATLS.

Complex genetic networks underlying the defensive system of rice (Oryza sativa L.) to Xanthomonas oryzae pv. oryzae

Complete resistance (CR) and partial resistance (PR) of rice (Oryza sativa L.) to its bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo), was genetically dissected by using 2 mapping populations and 10 Xoo races. Two CR genes, 50 quantitative resistance loci, and 60 digenic interactions were identified, which showed various degrees of race specificity to the Xoo races. The complex epistasis between these loci led us to the discovery of complex genetic networks underlying the rice defensive system to Xoo. The networks consisted of two major components: one representing interactions between alleles at the R loci of rice and alleles at the corresponding avirulence loci of Xoo for CR and the other comprising interactions between quantitative resistance loci in rice and their corresponding aggressiveness loci in Xoo for PR. The race specificity of PR and its strong genetic overlap with CR indicate that PR is essentially "weaker" CR. The genetic networks discovered are expected to maintain a high level of the allelic diversity at avirulent loci in the pathogen by stabilizing selection, which may maintain a high allelic diversity at R loci in the host by the frequency-dependent selection.

Longitudinal distribution of pulmonary vascular resistance with very high pulmonary blood flow

Dog left upper lobes (LUL) were perfused in situ via the left lower lobe artery. Lobe weight was continuously monitored. Increasing lobar flow from normal to 10 times normal had little effect on left atrial pressure, which ranged from 1 to 5 mmHg. There was a flow threshold (Qth) below which lobar weight was stable. Qth ranged from 1.1 to 1.55 l/min (mean 1.27) corresponding to four times normal LUL blood flow. Above Qth, step increases in lobar flow resulted in progressive weight gain at a constant rate that was proportional to flow. The effective pressure at the filtration site (EFP) at different flow rates was estimated from the static vascular pressure that resulted in the same rate of weight gain. From this value and from mean pulmonary arterial (PA) and left atrial (LA) pressures, we calculated resistance upstream (Rus) and downstream (Rds) from filtration site. At Qth, Rds accounted for 60% of total resistance. This fraction increased progressively with flow, reaching 83% at Q of 10 times normal. We conclude that during high pulmonary blood flow EFP is closer to PA pressure than it is to LA pressure, and that this becomes progressively more so as a function of flow. As a result, the lung accumulates water at flow rates in excess of four times normal despite a normal left atrial pressure.

Illusory limb movements in anosognosia for hemiplegia

To clarify the relation between anosognosia for hemiplegia and confabulation, 11 patients with acute right cerebral infarctions and left upper limb hemiparesis were assessed for anosognosia for hemiplegia, illusory limb movements (ILMs), hemispatial neglect, asomatognosia, and cognitive impairment. Five of 11 patients had unequivocal confabulation as evidenced by ILMs. The presence of ILMs was associated with the degree of anosognosia (p = 0.002), with hemispatial neglect (p<0.05), and with asomatognosia (p<0.01). The results confirm that a strong relation exists between anosognosia for hemiplegia and confabulations concerning the movement of the plegic limb. There is also a strong relation between ILMs and asomatognosia.

Cognitive and attitudinal impact of the Advanced Trauma Life Support program in a developing country

Improvement in trauma patient outcome has been reported after Advanced Training Life Support training (ATLS) in the developing country of Trinidad and Tobago (T & T). The cognitive impact of ATLS training was assessed from pre-ATLS and post-ATLS performance of T & T physicians in multiple choice question tests and comparison with post-ATLS test performance among Nebraska physicians. Overall, improvement between the pre-test and post-test among the T & T physicians was 22.0% +/- 2.0%. All physicians including failures (199 out of 212 passed) improved in their post-test scores. Individual item analysis of the post-test, including the KR-20 determination, varied but the overall performance was similar for both physician groups with the T & T physicians performing slightly better in test 2 (6 of 16 vs. 25 of 100 failures, p < 0.05). Attitudinal impact was assessed through 87 questionnaires from 50 physicians (92% response) and 37 nurses (89% response). Physicians (97.8% compared with 69.7%) were more aware of the ATLS training, and both groups (physicians, 77.3%; nurses, 69.6%) differentiated ATLS-trained physicians based on better resuscitation, more timely and appropriate consultation, greater confidence in trauma management, and improvement in trauma mortality and morbidity; all respondents recommended ATLS training for all emergency room physicians. The demonstrated positive cognitive and attitudinal effects very likely contributed to the improved post-ATLS trauma patient outcome.

Vascular endothelial cadherin (VE-cadherin): cloning and role in endothelial cell-cell adhesion

OBJECTIVE

To identify proteins responsible for intercellular junction integrity in human umbilical vein endothelial cells (HUVEC), we produced a monoclonal antibody that recognized an endothelial cell-specific, junctionally restricted protein. We characterized and cloned the antigen to study its functional properties.

METHODS

The size and cellular distribution of the antigen were determined by immunofluorescence and immunoprecipitation. The molecule was cloned and transfected into cell lines, and its role in cell-cell adhesion and growth rate was determined.

RESULTS

Monoclonal antibody hec1 recognizes VE-cadherin, an endothelial cell-restricted cell adhesion molecule. VE-cadherin is localized to the borders between apposing endothelial cells but is diffusely distributed on subconfluent or migrating cells. Transfection of fibroblasts with VE-cadherin imparts to them the ability to adhere to each other in a calcium-dependent homophilic manner. Expression of VE-cadherin over a several-log range does not change the growth rate of these cells.

CONCLUSIONS

Despite the fact that VE-cadherin is a "nonclassical" cadherin by structure, it functions as a classic cadherin by imparting to cells the ability to adhere in a calcium-dependent, homophilic manner. On HUVEC it appears to play a role in maintaining monolayer integrity.