This paper is a report on the first phase of a long-term, interdisciplinary project whose goal is to increase the overall effectiveness of physicians' time, and thus the quality of health care, by improving the information exchange between physicians and patients in clinical settings. We are focusing on patients with long-term and chronic conditions, initially on migraine patients, who require periodic interaction with their physicians for effective management of their condition. We are using medical informatics to focus on the information needs of patients, as well as of physicians, and to address problems of information exchange. This requires understanding patients' concerns to design an appropriate system, and using state-of-the-art artificial intelligence techniques to build an interactive explanation system. In contrast to many other knowledge-based systems, our system's design is based on empirical data on actual information needs. We used ethnographic techniques to observe explanations actually given in clinic settings, and to conduct interviews with migraine sufferers and physicians. Our system has an extensive knowledge base that contains both general medical terminology and specific knowledge about migraine, such as common trigger factors and symptoms of migraine, the common therapies, and the most common effects and side effects of those therapies. The system consists of two main components: (a) an interactive history-taking module that collects information from patients prior to each visit, builds a patient model, and summarizes the patients' status for their physicians; and (b) an intelligent explanation module that produces an interactive information sheet containing explanations in everyday language that are tailored to individual patients, and responds intelligently to follow-up questions about topics covered in the information sheet.

Anthropology, Cultural↗

PubMed1995

Superior nitrogen balance after laparoscopic-assisted colectomy.

BACKGROUND: Although early resumption of enteral feeding after gastrointestinal surgery results in improved nitrogen balance and lower infectious complications, no postoperative nutritional data after laparoscopic-assisted colectomy exists. OBJECTIVE: The authors prospectively compared nitrogen balance after laparoscopic-assisted colectomy versus open colectomy. METHODS: This is a series of colon resections (open, N = 10; laparoscopic-assisted, N = 9) at the Ferguson-Blodgett Hospital, Grand Rapids, Michigan, between January and March 1993. Nitrogen intake and 24-hour urine collections were performed on postoperative days 1, 3, and 7 for the analysis of total urinary nitrogen and urinary 3 methylhistidine-(3mH). RESULTS: The time to passage of flatus (4.7 +/- 0.6; 2.0 +/- 0.2), resumption of oral intake (6.1 +/- 0.7; 1.4 +/- 0.2; p < 0.05, Student's test), first bowel movement (5.2 +/- 1.0; 3.0 +/- 0.3; p < 0.05, Student;s t test), and discharge (10.3 +/- 1.3; 4.1 +/- 1.8; p < 0.05, Student's t test) occurred significantly earlier in the laparoscopic-assisted colectomy group. Overall hospital charges were lower in the laparoscopic-assisted colectomy group ($11,572 +/- $823 vs. $13,961 +/- $1050). The operative time was higher in the laparoscopic-assisted colectomy group (176 +/- 12 hours vs. 105 +/- 17 hours, p < 0.05,Student's test). Blood loss was higher in the open group (805 +/- 264 mL vs 217 +/- 32 mL, p < 0.05, Student's test). Urinary nitrogen losses were similar between the two groups; however, significantly more patients in the laparoscopic-assisted colectomy group achieved net positive nitrogen on day 3 (6/9; 0/10; p < 0.05, Fisher's exact test), and day 7 (9/9; 4/10; p < 0.05, Fisher's exact test). Infectious complications occurred less frequently in the laparoscopic-assisted colectomy group (0/9 vs. 4/10; p < 0.05, Fisher's exact test). CONCLUSIONS: Patients undergoing laparoscopic-assisted colectomy can achieve early resumption of enteral nutrition with earlier return to positive nitrogen balance compared with open colectomy. This may offer benefits of fewer infectious complications and lower cost of care.

Colectomy↗

PubMed1994

Evolution of transcription-regulating proteins by enzyme recruitment: molecular models for nitrogen metabolite repression and ethanol utilisation in eukaryotes.

Studies on the quinic acid utilisation gene (qut) cluster in Aspergillus nidulans showed that the genes encoding transcriptional activator and repressor proteins evolved by co-opting duplicated copies of genes encoding metabolic enzymes. In order to test the hypothesis that this was a general route for the genesis of regulatory proteins, the origins of the major control protein mediating nitrogen metabolite repression (an example of inter-pathway regulation) and ethanol utilisation (an example of intra-pathway regulation) in filamentous fungi were sought. The regulatory proteins mediating nitrogen metabolite repression were deduced to have originated in a duplication of genes encoding the anthranilate synthase complex which is active in the shikimate pathway. The major protein regulating ethanol utilisation was deduced to have its origin in the fusion of duplicated genes encoding the aldehyde and alcohol dehydrogenases (ALDA and ALCA). These data strongly support the view that transcriptional regulatory proteins evolve by the recruitment of functional domains provided by metabolic enzymes.

Aspergillus nidulans↗

PubMed1994

Crystallization of a type II dehydroquinase from Mycobacterium tuberculosis.

A type II 3-dehydroquinase from Mycobacterium tuberculosis has been crystallized in the presence of 6% polyethyleneglycol 6000. Data from these crystals have been collected to a resolution of 2.2 A on a rotating anode X-ray source. The space group has been determined as F23 with unit cell dimensions of a = b = c = 127.8 A. There is one molecule in the asymmetric unit.

Crystallization↗

PubMed1994

Efficient independent activity of a monomeric, monofunctional dehydroquinate synthase derived from the N-terminus of the pentafunctional AROM protein of Aspergillus nidulans.

The dehydroquinate synthase (DHQ synthase) functional domain from the pentafunctional AROM protein of Aspergillus nidulans has previously been overproduced in Escherichia coli [van den Hombergh, Moore, Charles and Hawkins (1992) Biochem J. 284, 861-867]. We now report the purification of this domain to homogeneity and subsequent characterization. The monofunctional DHQ synthase was found to retain efficient catalytic activity when compared with the intact pentafunctional AROM protein of Neurospora crassa [Lambert, Boocock and Coggins (1985) Biochem J. 226, 817-829]. The apparent kcat. was estimated to be 8 s-1, and the apparent Km values for NAD+ and 3-deoxy-D-arabino-heptulosonate phosphate (DAHP) were 3 microM and 2.2 microM respectively. These values are similar to those reported for the intact N. crassa enzyme, except that the apparent Km for NAD+ reported here is 15-fold higher. The monofunctional DHQ synthase domain is inactivated by treatment with chelating agents in the absence of substrates and is re-activated by the addition of metal ions; among those tested, Zn2+ gave the highest kcat./Km value. The enzyme is inactivated by diethyl pyrocarbonate; both the substrate, DAHP, and the product phosphate protected against inactivation. Size-exclusion chromatography suggested an M(r) of 43,000 for the monofunctional domain, indicating that it is monomeric and compactly folded. The c.d. spectrum confirmed that the domain has a compact globular conformation; the near-u.v. c.d. of zinc- and cobalt-reactivated domains were superimposable.

Alcohol Oxidoreductases↗

PubMed1994

A retrospective study of circovirus infection in pigeons: nine cases (1986-1993).

Circovirus infections were diagnosed in 12 pigeons from the United States 4 pigeons from Australia, and 1 pigeon from Canada (1986-1993). Circovirus was identified by electron microscopic examination of basophilic botryoid cytoplasmic inclusions that had a histologic appearance similar to that of psittacine beak and feather disease virus inclusions. Inclusions were seen in splenic, bursal, gut-associated, and bronchus-associated lymphoid tissue macrophages and in bursal epithelial cells. Inclusions were composed of paracrystalline arrays of tightly packed, nonenveloped icosahedral virions 14-17 nm in diameter. Histologic changes in the spleens ranged from lymphofollicular hyperplasia with mild discrete lymphocellular necrosis to lymphoid depletion and diffuse histiocytosis. Lesions in the bursa of Fabricius ranged from mild lymphocellular necrosis to severe cystic bursal atrophy. Remaining histologic findings coincided with concurrent bacterial, viral, fungal, and parasitic infections. Immunoperoxidase staining and DNA in situ hybridization demonstrated that pigeon circovirus is distinct from psittacine beak and feather disease virus; however both viruses apparently share some homologous DNA sequences. Clinical and diagnostic findings indicate that pigeon circovirus may be similar to psittacine beak and feather disease virus with respect to acquired immunodeficiency and subsequent multiple secondary infections.

Animals↗

PubMed1994

Generating patient-specific interactive natural language explanations.

Patient compliance is a significant problem and is strongly correlated with the patients' understanding of their condition and prescribed treatment. Since doctors typically do not have large amounts of time to educate patients, and impersonal, voluminous patient handouts are largely ineffective, we propose the use of a sophisticated computer-based information system to generate tailored, interactive handouts to communicate with patients. Our system uses text planning and user modeling techniques to generate natural language descriptions of migraine, its symptoms, triggering factors and prescriptions. The system is capable of handling follow-up questions requesting further information, and generating responses in the context of previously supplied information--a capability unavailable in previous patient information systems. The system tailors its interaction to: (i) the class of migraine patients, (ii) the individual patient, and (iii) the previous dialogue. Preliminary evaluation of the system indicates that patients find it useful and informative. More extensive evaluation is in progress.

Computer-Assisted Instruction↗

PubMed1994

Disseminated neoplastic cells in Mytilus trossulus: verification of host species origin by (16S-like) rRNA sequence comparison.

Disseminated neoplasia is a leukemia-like disease that occurs in many species of bivalve molluscs worldwide, including the bay mussel (Mytilus trossulus). The etiology of the disease is undetermined, but an early report proposed that the anomalous bivalve cells were actually an invasive parasite rather than cancerous cells of host origin. Comparison of partial sequences of small subunit rRNA from normal and putative cancer cells was performed to resolve this issue. These studies showed a close phylogenetic relationship of the different forms of cancer cells to each other (similarity coefficient, 0.982), to the normal hemocytes (similarity coefficient, 0.990, 0.992), and to the oyster, Crassostrea virginica (similarity coefficient, 0.895-0.927). A large phylogenetic distance separates all 3 mussel hemocyte types from several representative protists (similarity coefficient, 0.702-0.761). These results indicate that the disseminated neoplastic cells in mussels are indeed proliferative host cells and not unicellular parasites.

Animals↗

PubMed1993

Genesis of eukaryotic transcriptional activator and repressor proteins by splitting a multidomain anabolic enzyme.

The genes necessary for the correctly regulated catabolism of quinate in Aspergillus nidulans and Neurospora crassa are controlled at the level of transcription by a DNA-binding activator protein and a repressor protein that directly interact with one another. The repressor protein is homologous throughout its length with the three C-terminal domains of a pentafunctional enzyme catalysing five consecutive steps in the related anabolic shikimate pathway. We now report that the activator protein is homologous to the two N-terminal domains of the same pentafunctional enzyme and that this proposed structural similarity suggests a molecular mechanism by which the repressor recognises the activator protein. We believe that this is the first report of the genesis of a pair of interacting eukaryotic regulatory proteins by the splitting of a multidomain anabolic enzyme. The recruitment of preformed enzymatically active domains to a regulatory role may represent a general mechanism for the evolution of pathway-specific regulator proteins in dispensable pathways.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗

PubMed1993

Characterization of the 3-dehydroquinase domain of the pentafunctional AROM protein, and the quinate dehydrogenase from Aspergillus nidulans, and the overproduction of the type II 3-dehydroquinase from neurospora crassa.

The AROM protein of Aspergillus nidulans is a multidomain pentafunctional polypeptide that is active as a dimer and catalyses steps 2-6 in the prechorismate section of the shikimate pathway. The three C-terminal domains (including the type I 3-dehydroquinase) of the AROM protein are homologous with the qutR-encoded QUTR protein that represses transcription of the eight genes comprising the quinic acid utilization (qut) gene cluster, and the two N-terminal domains are homologous with the qutA-encoded QUTA protein that transcribes the qut genes. As part of a larger research programme designed to compare the structures of the three proteins and to probe the domain structure and interaction within each protein, we have overproduced and purified the 3-dehydroquinase domain of the AROM protein. Additionally we have overproduced and purified the qutB-encoded quinate dehydrogenase and overproduced the qa-2 encoded type II 3-dehydroquinase of Neurospora crassa. We report that the AROM 3-dehydroquinase domain has a monomeric native state, with an apparent kcat./Km ratio that is approx. 160-fold lower than the value for the native N. crassa AROM protein. The AROM protein 3-dehydroquinase domain is sensitive to inactivation by borohydride in the presence of the substrate 3-dehydroquinate, confirming that it is a typical type I 3-dehydroquinase. The purified quinate dehydrogenase is bifunctional, being able to metabolize shikimate as a substrate. The apparent Km values for quinate (450 microM), shikimate (1.7 mM) and NAD+ (150 microM) are all similar to values reported for the qa-3-encoded enzyme from N. crassa.

Alcohol Oxidoreductases↗

PubMed1993

Characterization of the type I dehydroquinase from Salmonella typhi.

The type I dehydroquinase from the human pathogen Salmonella typhi was overexpressed in an Escherichia coli host and purified to homogeneity. The S. typhi enzyme was characterized in terms of its kinetic parameters, important active-site residues, thermal stability and c.d. and fluorescence properties. In all important respects, the enzyme from S. typhi behaves in a very similar fashion to the well-characterized enzyme from E. coli, including the remarkable conformational stabilization observed on reduction of the substrate/product mixture by NaBH4. This gives confidence that the information from X-ray studies on the S. typhi enzyme [Boys, Fawcett, Sawyer, Moore, Charles, Hawkins, Deka, Kleanthous and Coggins (1992) J. Mol. Biol. 227, 352-355] can be applied to other type I dehydroquinases. Studies of the quenching of fluorescence of the S. typhi enzyme by succinimide show that NaBH4 reduction of the substrate/product imine complex involves a dramatic decrease in the flexibility of the enzyme, with only very minor changes in the overall secondary and tertiary structure.

Circular Dichroism↗

PubMed1993

Overproduction of, and interaction within, bifunctional domains from the amino- and carboxy-termini of the pentafunctional AROM protein of Aspergillus nidulans.

The pentafunctional AROM protein in Aspergillus nidulans and other fungi catalyses five consecutive enzymatic steps leading to the production of 5-enolpyruvylshikimate 3-phosphate (EPSP) in the shikimate pathway. The AROM protein has five separate enzymatic domains that have previously been shown to display a range of abilities to fold and function in isolation as monofunctional enzymes. In this communication, we report (1) the stable overproduction of a bifunctional protein containing the 3-dehydroquinate (DHQ) synthase and EPSP synthase activities in Escherichia coli to around 10% of the total cell protein; (2) that both the DHQ synthase and EPSP synthase activities in the overproduced fragment are enzymatically active as judged by their ability to complement aroA and aroB mutants of E. coli; (3) that the EPSP synthase domain is only enzymatically active when covalently attached to the DHQ synthase domain (the cis arrangement). When DHQ synthase and EPSP synthase are produced concomitantly by transcribing sequences encoding the individual domains from separate plasmids in the same bacterial cell (the trans arrangement) no overproduction or enzyme activity can be detected for the EPSP synthase domain; (4) the EPSP synthase domain can be stably overproduced as a fusion protein with glutathione S-transferase (GST), however the EPSP synthase in this instance is enzymatically inactive; (5) a protein containing an enzymatically inactive DHQ synthase domain in the cis arrangement with EPSP synthase domain is stably overproduced with enzymatically active EPSP synthase; (6) the two C-terminal domains of the AROM protein specifying the 3-dehydroquinase and shikimate dehydrogenase domains can be overproduced in A. nidulans using a specially constructed expression vector. This same bi-domain fragment however is not produced in E. coli when identical coding sequences are transcribed from a prokaryotic expression vector. These data support the view that multifunctional/multidomain proteins do not solely consist of independent units covalently linked together, but rather that certain individual domains interact to varying degrees to stabilise enzyme activity.

Alcohol Oxidoreductases↗