Sketching of Mirror-Symmetric Shapes.

This paper presents a system to create mirror-symmetric surfaces from free-form sketches. The system takes as input a hand-drawn sketch and generates a surface whose silhouette approximately matches the input sketch. The input sketch typically consists of a set of curves connected at their endpoints, forming T-junctions and cusps. Our system is able to identify the skewed-mirror and translational symmetry between the hand-drawn curves and uses this information to reconstruct the occluded parts of the surface and its 3D shape.

Acinetobacter baumanii folliculitis in a patient with AIDS.

Gram-negative folliculitis usually involves the face and develops in patients with acne or rosacea during long-term antibiotic therapy. Numerous pathogens have been found, but not, until now, Acinetobacter baumanii which has previously been recognized as an important cause of nosocomial infections and hospital outbreaks. We report here a case of A. baumanii folliculitis of the face, neck, arms and upper part of trunk in a patient with AIDS responding to intravenous treatment with ticarcillin-clavulanic acid. The bacterium was not found on healthy skin and the source of the infection remained unknown.

Ligand-induced strain in hydrogen bonds of the c-Src SH3 domain detected by NMR.

Changes in the molecular conformation of proteins can result from a variety of perturbations, and can play crucial roles in the regulation of biological activity. A new solution NMR method has been applied to monitor ligand-induced changes in hydrogen bond geometry in the chicken c-Src SH3 domain. The structural response of this domain to ligand binding has been investigated by measuring trans-hydrogen bond (15)N-(13)C' scalar couplings in the free state and when bound to the high affinity class I ligand RLP2, containing residues RALPPLPRY. A comparison between hydrogen bonds in high resolution X-ray structures of this domain and those observed via (h3)J(NC') couplings in solution shows remarkable agreement. Two backbone-to-side-chain hydrogen bonds are observed in solution, and each appears to play a role in stabilization of loop structure. Reproducible ligand-induced changes in trans-hydrogen bond scalar couplings are observed across the domain that translate into changes in hydrogen bond length ranging between 0.02 to 0.12 A. The observed changes can be rationalized by an induced fit mechanism in which hydrogen bonds across the protein participate in a compensatory response to forces imparted at the protein-ligand interface. Upon ligand binding, mutual intercalation of the two Leu-Pro segments of the ligand between three aromatic side-chains protruding from the SH3 surface wedges apart secondary structural elements within the SH3 domain. This disruption is transmitted in a domino-like effect across the domain through networks of hydrogen bonded peptide planes. The unprecedented resolution obtained demonstrates the ability to characterize subtle structural rearrangements within a protein upon perturbation, and represents a new step in the endeavor to understand how hydrogen bonds contribute to the stabilization and function of biological macromolecules.

Construction of a human topological model from medical data.

Medical imaging can provide data for useful views of the interior details of human anatomy. In addition to visualization, which in general has been the primary reason for obtaining these data, many other uses are possible. These include modeling of different elements and their inter-relationships-topological modeling, simulation of physical processes, analysis of movements, and validation of models. Here, we describe some of the modeling issues from medical imaging. The issues are particularly related to topological modeling of different anatomical elements: bones, muscles, articulations, etc. A three-dimensional topological modeler is presented with which anatomists and other users can build a topological database containing structural, topological, and mechanical information of anatomical elements.

Detection of exon deletions and duplications of the mismatch repair genes in hereditary nonpolyposis colorectal cancer families using multiplex polymerase chain reaction of short fluorescent fragments.

Large genomic deletions within the mismatch repair MLH1 and MSH2 genes have been identified in families with the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome, and their detection represents a technical problem. To facilitate their detection, we developed a simple semiquantitative procedure based on the multiplex PCR of short fluorescent fragments. This method allowed us to confirm in HNPCC families three known deletions of MLH1 or MSH2 and to detect in 19 HNPCC families, in which analysis of mismatch repair genes using classical methods had revealed no alteration, a deletion of exon 5 and a duplication of MSH2 involving exons 9 and 10. The presence of such duplications, the frequency of which is probably underestimated, must be considered in HNPCC families in which conventional screening methods have failed to detect mutations.

Inhibitor binding induces active site stabilization of the HCV NS3 protein serine protease domain.

Few structures of viral serine proteases, those encoded by the Sindbis and Semliki Forest viruses, hepatitis C virus (HCV) and cytomegalovirus, have been reported. In the life cycle of HCV a crucial role is played by a chymotrypsin-like serine protease encoded at the N-terminus of the viral NS3 protein, the solution structure of which we present here complexed with a covalently bound reversible inhibitor. Unexpectedly, the residue in the P2 position of the inhibitor induces an effective stabilization of the catalytic His-Asp hydrogen bond, by shielding that region of the protease from the solvent. This interaction appears crucial in the activation of the enzyme catalytic machinery and represents an unprecedented observation for this family of enzymes. Our data suggest that natural substrates of this serine protease could contribute to the enzyme activation by a similar induced-fit mechanism. The high degree of similarity at the His-Asp catalytic site region between HCV NS3 and other viral serine proteases suggests that this behaviour could be a more general feature for this category of viral enzymes.

[Hepatitis C epidemiology at a general hospital center. Management and natural history as a function of the manner of identification]. / Epidémiologie de l'hépatite C dans un centre hospitalier général. Prise en charge et histoire naturelle en fonction du mode de découverte.

OBJECTIVES: To study the epidemiological characteristics of patients with chronic hepatitis C virus followed in a primary referral hospital and the clinical influence of "systematic screening" defined as the screening of patients without symptoms and with known risk factors of hepatitis C (past transfusion, past or present intravenous drug use, haemodialysis) on the natural history and treatment of chronic hepatitis C virus. METHODS: The files of 311 consecutive patients who screened positive for anti-hepatitis C virus and were seen at the primary referral hospital, Creil, from January 1992 to February 1996, were analyzed. RESULTS: Patients who underwent "systematic screening" were younger with a shorter duration of infection. They were more often intravenous drug addicts and had lower alanine aminotransferase activity and Knodell scores than patients who underwent screening during "a diagnostic procedure", because of symptoms and/or abnormal liver biochemistry. Increased age at contamination and alcohol consumption of more than 40 g per day was associated with an increased risk of cirrhosis while patients who underwent "systematic screening" had a lower risk of cirrhosis and higher survival rate. Interferon therapy was attempted less often in anti-hepatitis C virus positive patients from "systematic screening" programs. CONCLUSIONS: Anti-hepatitis C virus positive patients from "systematic screening" programs had a benign disease and were rarely treated with interferon compared to anti-hepatitis C virus positive patients diagnosed during a "diagnostic procedure".

Observation of through-hydrogen-bond 2hJHC' in a perdeuterated protein.

It is demonstrated that J connectivity between amide protons and hydrogen-bond-accepting carbonyl carbons can be observed in perdeuterated human ubiquitin. A selective pulse scheme is used to detect these small 2hJHC' interactions in the presence of the much larger through-covalent-bond 2JHC' and 3JHC' couplings. The ratio of the observed through-H-bond correlation intensity and the 2JHC' connectivity observed in a reference spectrum indicates 2hJHC' values of ca. 0.4-0.6 Hz, which are only slightly smaller than the corresponding 3hJNC' values. However, for technical reasons, 2hJHC' couplings are more difficult to measure than 3hJNC'.

Measurement of 3hJNC' connectivities across hydrogen bonds in a 30 kDa protein.

A method is described which permits detection of 3hJNC' scalar couplings across hydrogen bonds in larger, perdeuterated proteins. The experiment is demonstrated for the uniformly 2H/13C/15N-enriched 30 kDa ribosome inactivating protein MAP30. The 3hJNC' interactions are smaller than 1 Hz, but their detection in an HNCO experiment is made possible through the use of constructive interference between the 15N chemical shift anisotropy and 1H-15N dipole-dipole relaxation mechanisms in a manner similar to that of recently proposed TROSY schemes. Sensitivity of the HNCO experiment depends strongly on the 15N transverse relaxation rate of the downfield 15N multiplet component and on the amide proton T1. In perdeuterated MAP30 at 40 degrees C, the average TROSY T2 was 169 ms at 750 MHz 1H frequency, and a wide range of longitudinal relaxation rates was observed for the amide protons.

A doublet-separated sensitivity-enhanced HSQC for the determination of scalar and dipolar one-bond J-couplings.

A simple, sensitivity-enhanced HSQC experiment is described which separates the upfield and downfield components in the indirect dimension into different subspectra. The sequence is similar to the generalized TROSY scheme; however, decoupling of the X-nucleus is used during detection. A detailed analysis of relaxation effects, precision and sensitivity of the method is presented. The approach is demonstrated in a two-dimensional water flip-back 1H-15N HSQC which measures 1JHN splittings in isotropic and oriented samples of ubiquitin and the hepatitis C protease. The results are in excellent agreement with splittings obtained from a conventional 1H-coupled HSQC.

Solution structure, rotational diffusion anisotropy and local backbone dynamics of Rhodobacter capsulatus cytochrome c2.

The solution structure, backbone dynamics and rotational diffusion of the Rhodobacter capsulatus cytochrome c2 have been determined using heteronuclear NMR spectroscopy. In all, 1204 NOE-derived distances were used in the structure calculation to give a final ensemble with 0.59(+/-0.08) A rms deviation for the backbone atoms (C, Calpha and N) with respect to the mean coordinates. There is no major difference between the solution structure and the previously solved X-ray crystal structure (1.07(+/-0.07) A rms difference for the backbone atoms), although certain significant local structural differences have been identified. This protein contains five helical regions and a histidine-heme binding domain, connected by a series of structured loops. The orientation of the helices provides an excellent sampling of angular space and thus allows a precise characterization of the anisotropic diffusion tensor. Analysis of the hydrodynamics of the protein has been performed by interpretation of the 15N relaxation data using isotropic, axially asymmetric and fully anisotropic diffusion tensors. The protein can be shown to exhibit significant anisotropic reorientation with a diffusion tensor with principal axes values of 1.405(+/-0.031)x10(7) s-1, 1.566(+/-0.051)x10(7) s-1 and 1.829(+/-0.054)x10(7) s-1. Hydrodynamic calculations performed on the solution structure predict values of 1.399x10(7) s-1, 1.500x10(7) s-1 and 1.863x10(7) s-1 when a solvent shell of 3.5 A is included in the calculation. The optimal orientation of the diffusion tensor has been incorporated into a hybrid Lipari-Szabo type local motion-anisotropic rotational diffusion model to characterize the local mobility in the molecule. The mobility parameters thus extracted show a quantitative improvement with respect to the model-free analysis assuming isotropic reorientation; helical regions exhibit similar dynamic properties and fewer residues require more complex models of internal motion. While the molecule is essentially rigid, a tripeptide loop region (residues 101 to 103) exhibits flexibility in the range of 20 to 30 ps, which appears to be correlated with the order in the NMR solution structure.

Early ritonavir-induced maculopapular eruption.

We report 2 cases of maculopapular eruption and fever in patients infected with human immunodeficiency virus (HIV) on the 2nd day of first administration of ritonavir, a protease inhibitor. In the 1st patient, clinical improvement occurred despite continuation of therapy, and in the 2nd the treatment was stopped with remission and rechallenge resulting in recurrence. Ritonavir should be added to the list of drugs that can induce adverse cutaneous reactions in HIV patients.

Measurement of (13)C (α)- (13)CO cross-relaxation rates in (15)N-/ (13)C-labelled proteins.

Internal motions play an important role in the biological function of proteins and NMR relaxation studies may characterize them over a wide range of frequencies. An experimental pulse scheme is proposed for the measurement of the (13)CO-(13)C(α) cross-relaxation rate. For sensitivity reasons, this measurement is performed in an indirect manner through several coherence transfer steps, which should thus be calibrated independently. Contributions of other relaxation pathways can be eliminated by the determination of the initial slope of the buildup curve. The cross-relaxation rates have been determined on a (15)N-/(13)C-labelled 116-residue protein and the significant variations along the sequence have been interpreted as evidence of an increased amount of fast local motion.

High-resolution 3D HNCOCA experiment applied to a 28 kDa paramagnetic protein.

A new triple-resonance 3D HNCOCA pulse scheme is presented, designed to identify the backbone nuclei (H(N), N, CO, C(α)) of doubly labelled proteins. The two carbon frequencies are labelled along the same indirect dimension and the corresponding dwell times can be independently scaled in order to account for the relaxation properties and chemical shift ranges of the CO and C(α). If one takes advantage of the symmetry properties of the spectra in the course of the peak picking, this 3D scheme has the same sensitivity as the 4D experiment, but with an improved resolution. The sequence is illustrated on a 0.5 mM sample of Rhodobacter capsulatus cytochrome c' a homodimeric paramagnetic protein of 2×14 kDa. A resonance assignment strategy, based on a low-concentration (13)C/(15)N-labelled sample and a more concentrated (15)N-labelled sample, is proposed for proteins where the expression system shows a limited efficiency.

[A probable case of Lyme Disease contracted in Mozambique]. / Un cas probable de borreliose de Lyme contractée au Mozambique.

This report deals with the first probably autochthonous case of Lyme disease occurred in Mozambique. The authors review the epidemiology of Lyme disease in Tropical Africa.