Genome of the bacterium Streptococcus pneumoniae strain R6

Streptococcus pneumoniae is among the most significant causes of bacterial disease in humans. Here we report the 2,038,615-bp genomic sequence of the gram-positive bacterium S. pneumoniae R6. Because the R6 strain is avirulent and, more importantly, because it is readily transformed with DNA from homologous species and many heterologous species, it is the principal platform for investigation of the biology of this important pathogen. It is also used as a primary vehicle for genomics-based development of antibiotics for gram-positive bacteria. In our analysis of the genome, we identified a large number of new uncharacterized genes predicted to encode proteins that either reside on the surface of the cell or are secreted. Among those proteins there may be new targets for vaccine and antibiotic development.

Demographic influences on mitochondrial DNA lineage survivorship in animal populations

Probability models of branching processes and computer simulations of these models are used to examine stochastic survivorship of female lineages under a variety of demographic scenarios. A parameter II, defined as the probability of survival of two or more independent lineages over G generations, is monitored as a function of founding size of a population, population size at carrying capacity, and the frequency distributions of surviving progeny. Stochastic lineage extinction can be very rapid under certain biologically plausible demographic conditions. For stable-sized populations initiated by n females and/or regulated about carrying capacity k = n, it is highly probable that within about 4n generations all descendants will trace their ancestries to a single founder female. For a given mean family size, increased variance decreases lineage survivorship. In expanding populations, however, lineage extinction is dramatically slowed, and the final k value is a far more important determinant of II than is the size of the population at founding. The results are discussed in the context of recent empirical observations of low mitochondrial DNA (mtDNA) sequence heterogeneity in humans and expected distributions of asexually transmitted traits among sexually reproducing species.

The role of extracellular spacer regions in the optimal design of chimeric immune receptors: evaluation of four different scFvs and antigens

Human peripheral blood lymphocytes can be transduced to express antigen-dependent CD3zeta chimeric immune receptors (CIRs), which function independently of the T-cell receptor (TCR). Although the exact function of these domains is unclear, previous studies imply that an extracellular spacer region is required for optimal CIR activity. In this study, four scFvs (in the context of CIRs with or without extracellular spacer regions) were used to target the human tumor-associated antigens carcinoembryonic antigen (CEA), neural cell adhesion molecule (NCAM), the oncofetal antigen 5T4, and the B-cell antigen CD19. In all cases human T-cell populations expressing the CIRs were functionally active against their respective targets, but the anti-5T4 and anti-NCAM CIRs showed enhanced specific cytokine release and cytotoxicity only when possessing an extracellular spacer region. In contrast, the anti-CEA and anti-CD19 CIRs displayed optimal cytokine release activity only in the absence of an extracellular spacer. Interestingly, mapping of the scFv epitopes has revealed that the anti-CEA scFv binds close to the amino-terminal of CEA, which is easily accessible to the CIR. In contrast, CIRs enhanced by a spacer domain appear to bind to epitopes residing closer to the cell membrane, suggesting that a more flexible extracellular domain may be required to permit the efficient binding of such epitopes. These results show that a spacer is not necessary for optimal activity of CIRs but that the optimal design varies.

Mechanism of coaggregation between Actinomyces viscosus T14V and Streptococcus sanguis 34

Actinomyces viscosus T14V and Streptococcus sanguis 34 coaggregate by a mechanism which is not inhibited by 1 M NaCl, is dextran independent, requires calcium, is pH dependent with an optimum at pH 8.0 to 8.5, and appears to require the interaction of a protein or glycoprotein on A. viscosus with a carbohydrate on S. sanguis. The coaggregation is inhibited more than 80% by 0.01 M lactose, 0.02 M beta-methyl-D-galactoside, or 0.05 M D-galactose; inhibition of coaggregation was less than 10% in 0.1 M alpha-methyl-D-galactoside, melibiose, maltose, cellobiose, sucrose, and a number of monosaccharides. At very high concentrations of enzyme, protease from S. griseus destroyed the reactive site on A. viscosus but not on S. sanguis. Both were totally resistant to dextranase. Periodate (0.01 M; pH 4) inactivated both bacteria. The ability of S. sanguis to coaggregate with A. viscosus was not destroyed by phenol-water extraction at 65 degrees C for 15 min. When the bacteria were cultured under specified conditions, the coaggregation was highly reproducible. Under the same conditions, T14AV, the avirulent mutant of A. viscosus T14V, did not coaggregate with S. sanguis 34. Electron microscopic studies of coaggregates, labeled immunochemically with antibody to A. viscosus, indicated that fibrils on A. viscosus may be involved in the coaggregation.

Chromosome-specific recombinant DNA libraries from the fungus Aspergillus nidulans

Development of physical genomic maps is facilitated by identification of overlapping recombinant DNA clones containing long chromosomal DNA inserts. To simplify the analysis required to determine which clones in a genomic library overlap one another, we partitioned Aspergillus nidulans cosmid libraries into chromosome-specific subcollections. The eight A. nidulans chromosomes were resolved by pulsed field gel electrophoresis and hybridized to filter replicas of cosmid libraries. The subcollections obtained appeared to be representative of the chromosomes based on the correspondence between subcollection size and chromosome length. A sufficient number of clones was obtained in each chromosome-specific subcollection to predict the overlap and assembly of individual clones into a limited number of contiguous regions. This approach should be applicable to many organisms whose genomes can be resolved by pulsed field gel electrophoresis.

Verteporfin therapy of subfoveal choroidal neovascularization in patients with age-related macular degeneration: additional information regarding baseline lesion composition's impact on vision outcomes-TAP report No. 3

OBJECTIVE

To explore how baseline lesion composition influenced vision outcomes in patients with age-related macular degeneration (AMD) undergoing photodynamic therapy with verteporfin (Visudyne) for subfoveal choroidal neovascularization (CNV) in the Treatment of Age-Related Macular Degeneration With Photodynamic Therapy Investigation.

METHODS

Patients with subfoveal lesions secondary to AMD with evidence of classic CNV were categorized into 2 subgroups based on baseline color photographs and fluorescein angiograms assessed by graders at the Wilmer Photograph Reading Center (The Johns Hopkins University School of Medicine) before any outcome analyses as follows: (1) predominantly classic CNV (area of classic CNV >/=50% of the area of the entire lesion) or (2) minimally classic CNV (area of classic CNV <50% but >0% of the area of the entire lesion). Additional exploratory analyses were performed in the predominantly classic subgroup to investigate the effects of visual acuity, lesion size, prior laser photocoagulation, phakic status, micronutrient use, and presence of occult CNV on vision outcomes.

MAIN OUTCOME MEASURES

Subgroup analyses of vision and fluorescein angiographic outcomes at 1 and 2 years after study enrollment were examined in an intent-to-treat analysis from 2 multicenter, double-masked, placebo-controlled, randomized clinical trials.

RESULTS

Compared with patients who had minimally classic CNV, patients with predominantly classic CNV had a worse initial mean visual acuity and smaller lesions and were more likely to have lesions that included blood or blocked fluorescence. When evaluated by treatment assignment and lesion composition, 84% to 88% completed the month 24 examination. In the subgroup with predominantly classic lesions, visual acuity outcomes were consistently better in verteporfin-treated patients. Outcomes for patients with predominantly classic lesions without occult CNV tended to be better than outcomes for patients with predominantly classic lesions with occult CNV, although the former tended to have smaller lesions and lower levels of visual acuity at baseline. Contrast sensitivity and fluorescein angiographic outcomes (total lesion size, progression of classic CNV, and absence of classic CNV) were better in verteporfin-treated patients than in placebo-treated patients in the predominantly classic and the minimally classic CNV subgroups. In patients with predominantly classic CNV, no interaction of the treatment benefit by phakic status, micronutrient use, or prior laser photocoagulation therapy was noted.

CONCLUSIONS

Verteporfin therapy can safely reduce the risk of moderate and severe vision loss in patients with subfoveal lesions that are predominantly classic CNV secondary to AMD. While this benefit seemed to be even greater in the absence of occult CNV, the effect may be related to the smaller lesions and worse visual acuity associated with predominantly classic lesions without occult CNV and not solely to the lesion composition itself. These analyses support initial reports that verteporfin therapy should be used to treat patients with AMD who have predominantly classic CNV, with or without occult CNV, but suggest that further investigations should be performed to determine if lesions with a minimally classic composition might benefit when they are smaller and have lower levels of visual acuity.

Definition and properties of disequilibrium statistics for associations between nuclear and cytoplasmic genotypes

We define and establish the interrelationships of four components of statistical association between a diploid nuclear gene and a uniparentally transmitted, haploid cytoplasmic gene: an allelic (gametic) disequilibrium (D), which measures associations between alleles at the two loci; and three genotypic disequilibria (D1, D2, D3), which measure associations between two cytotypes and the three respective nuclear backgrounds. We also consider an alternative set of measures, including D and the residual disequilibrium (d). The dynamics of these disequilibria are then examined under three conventional models of the mating system: (1) random mating; (2a) assortative mating without dominance (the "mixed-mating model"); and (2b) assortative mating with dominance ("O'Donald's model"). The trajectories of gametic disequilibria are similar to those for pairs of unlinked nuclear loci. The dynamics of genotypic disequilibria exhibit a variety of behaviors depending on the model and the initial conditions. Procedures for statistical estimation of cytonuclear disequilibria are developed and applied to several real and hypothetical data sets. Special attention is paid to the biological interpretations of various categories of allelic and genotypic disequilibria in hybrid zones. Genetic systems for which these statistics might be appropriate include nuclear genotype frequencies in conjunction with those for mitochondrial DNA, chloroplast DNA, or cytoplasmically inherited microorganisms.

Topical iodine-containing antiseptics and neonatal hypothyroidism in very-low-birthweight infants

The thyroid function of very-low-birthweight (VLBW; below 1500 g) infants admitted to neonatal intensive-care units was studied at two hospitals; one routinely used topical iodinated antiseptic agents and the other used chlorhexidine-containing antiseptics. Serial monitoring of urinary iodine excretion and serum thyrotropin and thyroxine levels was undertaken from birth for the first 4 weeks of life. Urinary iodine excretion rose dramatically in the 54 iodine-exposed infants and was up to fifty times greater than in the 29 non-exposed infants. Within 14 days, 25% (9 of 36) of the infants exposed to iodine had serum thyrotropin levels above 20 mIU/l, compared with none of the control group. The mean serum thyroxine level in these 9 infants (44.1 nmol/l) was significantly lower than that in exposed infants with normal thyrotropin levels (83.1 nmol/l) and in the non-exposed control group (83.0 nmol/l); thyroxine levels fell before serum thyrotropin rose. These disturbances in thyroid function correlated positively with urinary iodine excretion and hence iodine absorption. Thyroid function had returned to normal by the time of discharge from hospital. It is concluded that iodine absorption, from topical iodine-containing antiseptics, may cause hypothyroidism during a critical period of neurological development in the newborn infant. The routine use of iodine antisepsis in VLBW infants should be avoided because of this effect.

DNA microsatellite instability and mismatch repair protein loss in adenomas presenting in hereditary non-polyposis colorectal cancer

BACKGROUND AND AIM

Hereditary non-polyposis colorectal cancer (HNPCC), as its name implies, is associated with few adenomas, and the early evolution of colorectal neoplasia is poorly understood. In this study our aim was to clarify the genetic profiles of benign polyps in subjects with HNPCC using a combined molecular and immunohistochemical approach.

METHODS

Thirty adenomas and 17 hyperplastic polyps were obtained from 24 affected HNPCC subjects. DNA was extracted from paraffin embedded tissue by microdissection and analysed for the presence of microsatellite instability (MSI) and mutations in five genes known to be targets in mismatch repair deficiency (TGFbetaRII, IGF2R, BAX, hMSH3, and hMSH6). Serial sections were stained by immunohistochemistry for hMLH1 and hMSH2.

RESULTS

Twenty four (80%) of 30 adenomas showed MSI. Of MSI positive adenomas, 66.7% showed MSI at more than 40% of markers (high level of MSI (MSI-H)). Two of 17 hyperplastic polyps revealed MSI at one marker (low level of MSI (MSI-L)). A significant association was found between MSI-H and high grade dysplasia in adenomas (p=0.004). Eight of nine adenomas with mutations of coding sequences revealed high grade dysplasia and all nine were MSI-H. Four of the nine ranged in size from 2 to 5 mm. The presence of the hMSH6 mutation was significantly correlated with high levels of MSI (80% of markers) (p<0.02). Twenty four adenomas gave evaluable results with immunohistochemistry. One of six (17%) microsatellite stable, six of seven (86%) MSI-L, and 11 of 11 (100%) MSI-H adenomas showed loss of either hMLH1 or hMSH2.

CONCLUSIONS

Most adenomas in subjects with a definite diagnosis of HNPCC show MSI (80%). The finding of MSI-L is usually associated with loss of expression of hMLH1 or hMSH2, unlike the situation in MSI-L sporadic colorectal cancer. The transition from MSI-L to MSI-H correlated with the finding of high grade dysplasia and mutation of coding sequences and may be driven by mutation of secondary mutators such as hMSH3 and hMSH6. Advanced genetic changes may be present in adenomas of minute size.

Evolution of reticular pseudodrusen

AIMS

To report observations relating to the clinical recognition and possible basis of reticular pseudodrusen (RPD).

METHODS

This retrospective study reports the evolution of RPD in 166 patients who had follow-up of over 1 year using multiple imaging techniques. Mean age when first seen was 73.3 years and the mean period of observation was 4.9 years (range 1-18 years). Associated macular changes were recorded.

RESULTS

RPD were first identified in the upper fundus as a reticular network, which then became less obvious, developing a diffuse yellowish appearance. RPD also faded around choroidal neovascularisation (CNV). RPD therefore could be transient but the pattern often remained visible outside the macula or nasal to the discs. Manifestations of age-related macular degeneration (AMD) were present in nearly all eyes and there was a particularly high association with CNV (52.1%). In one clinicopathological case abnormal material was found in the subretinal space.

CONCLUSIONS

The prevalence of RPD may be underestimated because their recognition depends upon the imaging method used, the area of fundus examined and the confusion with typical drusen. The pathology of one eye suggests that RPD may correspond to material in the subretinal space.

International emergency medicine and the recent development of emergency medicine worldwide

Emergency medicine is being established as a unique and independent specialty throughout the world. Two major models of emergency care delivery exist in the world today: the Anglo-American and the Franco-German model. Most countries developing new systems of emergency care are following the Anglo-American model and are recapitulating the sequence of steps taken to establish the systems of emergency medicine in the United States. The most important step in the development of emergency medicine in other countries is the recognition that emergency medicine incorporates a unique body of knowledge requiring specialized practitioners or emergency physicians. A global network of international emergency medicine is assisting the development of emergency medicine worldwide and now includes international organizations, academic institutions, and individuals in countries where emergency medicine is mature and their counterparts in countries where emergency medicine is developing. The multilevel exchange of information through various modalities, such as international conferences, physician exchange programs, and print or electronic media, is playing a vital role in the search for internationally applicable systems of emergency care.

Continuous interleukin-2 and lymphokine-activated killer cells for advanced cancer: a National Biotherapy Study Group trial

We conducted a multicenter, phase II trial of continuous-infusion recombinant interleukin-2 (rIL-2) and lymphokine-activated killer (LAK) cells. Patients had advanced cancer, measurable disease, and a good performance level. Treatment included a 5-day continuous infusion of 18 x 10(6) IU/m2/d of rIL-2 followed by 1 day of rest, 4 days of leukapheresis to collect cells for in vitro augmentation of cellular cytotoxicity, and 5 more days of rIL-2 infusion with reinfusion of LAK cells for 3 successive days. Therapy was repeated after 2 weeks. There were 117 patients enrolled: 63% were males, with a median age of 51 years. Eighty-two percent were managed in oncology units, and 18% were in intensive care units. Six patients died within 1 month of initiating therapy. In renal cell carcinoma, the response rate was one of 31 patients (3%), with a median survival of 10.7 months. In melanoma, the response rate was four of 33 patients (12%), with a median survival of 6.1 months. For all other histologies, response rate was three of 53 patients (5%), with a median survival of 7.4 months. All responders were asymptomatic when therapy was initiated. This trial confirms the feasibility of administering continuous rIL-2 and LAK cells outside the intensive care unit environment. Antitumor activity in melanoma was similar to that seen in multicenter trials of bolus rIL-2 and LAK cells. Activity in renal cell cancer was disappointing.

Ubiquitin in health and disease

Studies in recent years have shown that ubiquitin has increasingly important functions in eukaryotic cells; roles which were previously not suspected in healthy and diseased cells. The interplay between molecular pathological and molecular cell biological findings has indicated that ubiquitin may be pivotal in the cell stress response in chronic degenerative and viral diseases. Furthermore, the studies have led to the notion that ubiquitination may not only serve as a signal for nonlysosomal protein degradation but may be a unifying covalent protein modification for the major intracellular protein catabolic systems; these can act to identify proteins for cytosolic proteinases or direct intact and fragmented proteins into the lysosome system for breakdown to amino acids. This unifying role could explain why ubiquitin is restricted to eukaryotic cells, which possess extensive endomembrane systems in addition to a nuclear envelope. Protein ubiquitination is a feature of most filamentous inclusions and certain other intracellular conglomerates that are found in some degenerative and viral diseases. The detection of ubiquitin-protein conjugates is not of great diagnostic importance in these diseases. Protein ubiquitination is not only essential for the normal physiological turnover of proteins but appears to have been adapted as part of an intracellular surveillance system that can be activated by altered, damaged, or foreign proteins and organelles. The purpose of this system is to isolate and eliminate these noxious structures from the cell: as a cytoprotective mechanism this appears to have evolved in the cell akin perhaps to an 'intracellular immune system'. Other heat shock proteins such as hsp 70 may be involved in this process. It is apparent that ubiquitin has a role in embryonic development. Protein ubiquitination is presumably involved in the reorganisation of cytoplasm that accompanies cell differentiation. Ubiquitin is also necessary for the gross intracellular degradative processes which are consequent upon programmed cell death. Cell elimination is of key importance for a number of developmental morphogenetic changes. An understanding of the molecular details of these processes will no doubt provide further insights into the wide ranging roles of ubiquitin in the life process. As it says in the book 'Ubiquitin'; there is no doubt that ubiquitin is a 'lucky' protein. It is lucky in many ways: lucky for scientific progress, lucky for biomedical scientists and lucky for life! If you have not already done so, why don't you get lucky and look for a role for ubiquitin in your experimental system. As Avram Hershko has said "there is plenty to go round"!

Continuous interleukin-2 and tumor-infiltrating lymphocytes as treatment of advanced melanoma. A national biotherapy study group trial

Melanoma metastases were harvested from 82 patients for the purpose of growing and expanding tumor-infiltrating lymphocytes (TIL). Tumor tissue cell suspensions were incubated with interleukin-2 (IL-2), followed by repeated exposure to tumor antigen with or without OKT3 monoclonal antibody (MoAb). Initial growth success was achieved in 56 of 82 cultures (72%). Efforts were made to expand 26 of these 56 cultures for therapeutic TIL; 23 of 26 early cultures (88%) were successfully expanded for in vivo therapy. It took a mean of 78.5 +/- 25.4 days to grow sufficient TIL for treatment. Therapy included cyclophosphamide (1 g/m2) on day 1, followed by a 96-hour continuous infusion of IL-2 (18 x 10(6) IU/m2/d) on days 2 to 5, and approximately 10(11) (mean 1.49 +/- 0.93 x 10(11)) TIL on day 2. Patients who responded received monthly IL-2 as a 96-hour infusion. Median patient age was 45 years of age. Sixty-seven percent of the patients were men. Performance status was 0 to 1 in 77% of patients. Thirty-four percent of the patients had liver metastases. The usual IL-2 toxicities were seen. Response rate for 21 patients was 24% (95% confidence interval, 10% to 49%). One complete response was achieved with cells 98% CD4+; four partial responses were achieved with cells 80%, 94%, 98%, and 98% CD8+, respectively. Four of eight patients who received TIL, which had never been stimulated with OKT3, had tumor response. The authors conclude that a treatment plan for IL-2/TIL is technically difficult, costly, and effective for only a minority of patients. Overall, clinical results are not clearly superior to those obtained with other IL-2 regimens.

An overview and recent progress in the chemistry of uranium extraction from seawater

This review provides a brief background on the extraction of uranium from seawater as well as recent work by the United States Department of Energy on this project. The world's oceans contain uranium at 3 parts per billion, and despite this low concentration, there has been historical interest in harvesting it, mainly in Japan in the 1980s and the United States in this decade. Improvements in materials, chemistry, and deployment methods have all been made, with the ultimate goal of lower cost. This has been partially realized, dropping from approximately $2000 per kg U₃O₈ extracted in 1984 to $500 per kg today, although this is not yet competitive with terrestrial uranium. This technology may become cost-competitive if the cost of land-based uranium rises, especially if seawater extraction technology is improved further. The coordination chemistry aspects of the project are described in more detail, exploring the functional groups that are present on typical polymer sorbents as well as small-molecule analogues of these ligands. Selectivity for uranium over other metals, particularly vanadium, remains problematic, and techniques to both quantify binding strength and selectivity in order to overcome this issue are essential for future cost improvements.

Reactivity of a titanium dinitrogen complex supported by guanidinate ligands: investigation of solution behavior and a novel rearrangement of guanidinate ligands

The titanium dinitrogen complex, [[(Me(2)N)C(N(i)Pr)(2)]( 2)Ti](2)(N(2)) (2), was synthesized by reduction of the dichloride precursor, [(Me(2)N)C(N(i)Pr)(2)](2)TiCl(2) (1). The dinitrogen complex reacts with phenyl azide to yield the titanium imido complex, [(Me(2)N)C(N(i)Pr)(2)](2)TiNPh (3). The fluxional behavior of the guanidinate ligands in compounds 1-3 was investigated using variable temperature and two-dimensional NMR techniques; guanidinate ligand rotation and racemization reactions were observed. Rearrangement of the guanidinate ligand to an asymmetrical bonding mode utilizing the dimethylamino and amide-nitrogen atoms is observed in the bridging oxo and sulfido derivatives (4 and 5). These compounds are formed by the reactions of 2 with pyridine N-oxide and propylene sulfide, respectively. The ligand rearrangement was observed to be reversible for the bridging sulfido complex 5; the structure of this compound is sensitive to temperature and solvent. The solid-state and solution structures of compounds 1-5 are discussed.

Comparison of the nucleotide sequence of soybean 18S rRNA with the sequences of other small-subunit rRNAs

We present the sequence of the nuclear-encoded ribosomal small-subunit RNA from soybean. The soybean 18S rRNA sequence of 1807 nucleotides (nt) is contained in a gene family of approximately 800 closely related members per haploid genome. This sequence is compared with the ribosomal small-subunit RNAs of maize (1805 nt), yeast (1789 nt), Xenopus (1825 nt), rat (1869 nt), and Escherichia coli (1541 nt). Significant sequence homology is observed among the eukaryotic small-subunit rRNAs examined, and some sequence homology is observed between eukaryotic and prokaryotic small-subunit rRNAs. Conserved regions are found to be interspersed among highly diverged sequences. The significance of these comparisons is evaluated using computer simulation of a random sequence model. A tentative model of the secondary structure of soybean 18S rRNA is presented and discussed in the context of the functions of the various conserved regions within the sequence. On the basis of this model, the short base-paired sequences defining the four structural and functional domains of all 18S rRNAs are seen to be well conserved. The potential roles of other conserved soybean 18S rRNA sequences in protein synthesis are discussed.

Retinal microembolism during cardiopulmonary bypass demonstrated by fluorescein angiography

Fluorescein angiography was used to study retinal microvascular perfusion in 20 patients undergoing coronary artery surgery. Colour retinal photographs and fluorescein angiograms were obtained preoperatively and at 5-14 days postoperatively. In 10 patients retinal fluorescein angiograms were also obtained intraoperatively during cardiopulmonary bypass, and all were found to have retinal microvascular occlusions after 40-160 min of extracorporeal circulation. 3 patients had in addition focal leakage of fluorescein, and 6 had foci of abnormal drainage of dye. These changes are consistent with retinal microembolism, and appeared to have resolved by the time of the postoperative study. No new pathological features appeared in the retina after surgery. Intraoperative fluorescein angiography of the retina may prove valuable for investigation of cerebrovascular microembolism in the territory of the internal carotid artery during cardiopulmonary bypass in man.

Positional asphyxia during law enforcement transport

Three cases of positional asphyxia are described that occurred while victims were in a prone position in rear compartments of police patrol cars. These deaths are attributed to positional asphyxia. Autopsy findings and specific scene and circumstantial correlations of the investigation are discussed with emphasis placed on the limitations of interpretation of the anatomic changes at autopsy.

3D models of blood flow in the cerebral vasculature

The circle of Willis (CoW) is a ring-like arterial structure located in the base of the brain and is responsible for the distribution of oxygenated blood throughout the cerebral mass. To investigate the effects of the complex 3D geometry and anatomical variability of the CoW on the cerebral hemodynamics, a technique for generating physiologically accurate models of the CoW has been created using a combination of magnetic resonance data and computer-aided design software. A mathematical model of the body's cerebral autoregulation mechanism has been developed and numerous computational fluid dynamics simulations performed to model the hemodynamics in response to changes in afferent blood pressure. Three pathological conditions were explored, namely a complete CoW, a fetal P1 and a missing A1. The methodology of the cerebral hemodynamic modelling is proposed with the potential for future clinical application in mind, as a diagnostic tool.

Increased whole body protein breakdown predominates over increased whole body protein synthesis in multiple organ failure

1. Whole body protein turnover was measured using a primed-constant infusion of L-[1-13C]leucine with measurement of breath 13CO2 production and plasma 13C alpha-ketoisocaproate enrichment. Ten fasting patients, requiring mechanical ventilation and suffering from multiple organ failure, and six healthy control subjects were studied. 2. Protein breakdown and leucine removal from the plasma for protein synthesis were significantly higher in the patients than in the control subjects (P < 0.01). In addition, leucine oxidation was almost 75% higher in the patients than in the healthy control subjects (P < 0.05). 3. Plasma concentrations of glucose, insulin and growth hormone were not different between the two groups, but those of glucagon (not significant), noradrenaline (P < 0.05) and cortisol (P < 0.01) were almost two- and three-fold higher in the patients than in the control subjects. 4. Mean energy expenditure, measured by indirect calorimetry, was 30% higher in the patients than in the healthy control subjects (P < 0.01). 5. Combining the data from both groups of subjects and using multiple regression analysis, cortisol was found to be the most significant predictor of (i) protein breakdown (48% of variance explained), (ii) leucine oxidation (69%) and (iii) hourly energy expenditure (54%). 6. The present investigation using [13C]leucine tracer methods demonstrated, in patients with multiple organ failure, that whole body protein breakdown and synthesis increased concomitantly and were twice as high as rates measured in healthy control subjects. Of the hormones measured in the present study, cortisol appears to have the most significant effect on whole body protein turnover.

The effect of additional characters on choice of referring expression: Everyone counts

Two story-telling experiments examine the process of choosing between pronouns and proper names in speaking. Such choices are traditionally attributed to speakers striving to make referring expressions maximally interpretable to addressees. The experiments revealed a novel effect: even when a pronoun would not be ambiguous, the presence of another character in the discourse decreased pronoun use and increased latencies to refer to the most prominent character in the discourse. In other words, speakers were more likely to call Minnie Minnie than shewhen Donald was also present. Even when the referent character appeared alone in the stimulus picture, the presence of another character in the preceding discourse reduced pronouns. Furthermore, pronoun use varied with features associated with the speaker's degree of focus on the preceding discourse (e.g., narrative style and disfluency). We attribute this effect to competition for attentional resources in the speaker's representation of the discourse.