A METHOD TO IDENTIFY AND LOCALIZE A SINGLE HOT PARTICLE IN THE LUNGS USING AN ARRAY OF HIGH-PURITY GERMANIUM DETECTORS FOR IMPROVED ESTIMATE OF THE DEPOSITED ACTIVITY

A new method has been developed to identify and localize a single hot particle in the lungs using an array of four high-purity germanium detectors. The method is based upon calculating a set of three count rate ratios (generated by each individual detector in the array) that are evaluated in sequence to designate whether the measured deposition can be associated with a hot particle rather than the default assumption of a uniform activity distribution. Identification and localization of the hot particle are determined from a single in vivo measurement in which detectors are positioned above and below the thorax. The method was tested using an anthropomorphic thorax phantom in which point sources of 241Am, 137Cs and 60Co were individually inserted in the lungs at 15 different locations and were measured using a scanning bed whole-body counter. Depending upon source location and photon energy, a bias of -35% up to +76% could be introduced by falsely assuming a uniform activity distribution in the lungs. This bias would directly translate to an erroneous dose estimate to the lungs. It was demonstrated that by using the appropriate detector efficiencies for the single hot particle, the bias associated with the activity determination is reduced to <10% and ~2% in average.

Stereotactic Body Radiation Therapy (SBRT) for prostate cancer: Preliminary results of toxicity

To the Editor, Prostate cancer is the second most common cancer in men in Morocco after lung cancer. External radiotherapy (RTE) is a curative therapeutic option for localized prostate cancer, However the conventional RTE remains a long treatment (7- 8 weeks, 5 days a week) which is demanding for patients and make difficult to manage the waiting lists. The development of imaging and irradiation techniques over the last decades has allowed a high precision in the delivery of the dose to the target organ and a better protection of the organs at risk (OAR), which has encouraged the hypo fractionated irradiation of localized prostate cancer, especially after the results of radiobiology studies that suggested a low report a/b for the prostate.

Innovative Non-Irradiating and Non-Invasive Per Fraction Control System in Radiotherapy: Surface-Guided Radiation Therapy Experience of Casablanca Cancer Center

Purpose: Evaluation of the added value of radiotherapy guided by the cutaneous   surface in the positioning and monitoring of the radiotherapy   Patients and Methods: This study included 21 consecutive patients treated with an   accelerator dedicated to "True Beam®" stereotactic radiotherapy whose sessions were   monitored by an Optical Surface Monitoring System: "OSMS®". Excluded from our   study were treatments controlled exclusively by radiological imaging (IGRT).   Positioning variabilities were compared between conventional imaging and skin   surface infrared (OSMS) monitoring. Conventional imaging was in the form of   standard radiography (KV) performed during the treatment session or three-   dimensional by a series of Cone Beam computerized tomography (CBCT) scanned   images made at the beginning and end of The total time of the session and   the positioning variability’s in the 3 planes were   14   Results: The results of our study show that the cutaneous surface monitoring allowed   to obtain a faster alignment of the patient with an improvement in the overall time of   the session with a mean at 32% [14.5-49.27%], likewise a sub-millimeter positioning   quality for all locations with a median longitudinal distance of 0.02 cm [0-0.66], 01   cm verticality [0-0.32] and laterality 0.02 cm [0-0.77] This benefit is significantly   greater for cerebral and Head and neck’s localizations   21   Conclusion: Optical Surface Monitoring System (OSMS®) is a non-invasive and non-   irradiating means that allows reliable and fast  

Anal Cancer with Atypical Brain and Cranial Bones Metastasis: About 2 Cases and Literature Review

Canal anal cancer is a rare tumor that accounts for 2% of all colorectal neoplasms, with a low propensity for metastasis. The spread of anal squamous cell carcinoma to the brain is exceedingly rare and has been previously reported only 5 times in the medical literature. However, the first and only case of cranial bone metastasis from anal canal carcinoma was described in 2019. The purpose of this article is to add our cases to the limited literature for the management of metastatic anal cancer. The current study presents 2 cases of patients diagnosed with squamous cell carcinoma of the anal canal how underwent chemo and radiotherapy. Despite the treatment our patients developed neurological symptoms, cerebral magnetic resonance imaging showed brain lesions for the first case, and cranial bones metastasis for the second one, histopathology confirmed these lesions to be a poorly differentiated squamous cell carcinoma, consistent with the known primary tumor of the anal canal. Unfortunately, both patients succumbed quickly to systemic complications of the disease during these treatments. Despite its rarity, brain metastasis should be considered in any patient with a history of anal cancer presented neurological symptoms.

Chondrosarcoma of the parapharyngeal space: Case report and literature review of an extremely rare location

Chondrosarcoma of the head and neck region is a rare disease, representing approximately 0.1% of all head and neck neoplasms. Parapharyngeal location is extremely rare and low-grade ones are even rarer. Surgery alone or followed by adjuvant radiotherapy is the treatment of choice. In this article, we report a case of a 67-year-old male with low-grade parapharyngeal chondrosarcoma who presented with a 3-month history of dysphagia. A cervical magnetic resonance imaging was performed that shows a well-defined mass located at the right parapharyngeal space, causing medial deviation of the mucosal space. Surgical resection of the tumor without neck dissection followed by adjuvant radiotherapy was undertaken with a favorable response. The purpose of this article is to add our case to the limited literature for good management of parapharyngeal chondrosarcomas.

Rare location of head and neck adenoid cystic carcinoma

Adenoid Cystic Carcinoma of larynx is extremely rare location. We herein describe an unusual clinical and radiological presentation of ACCL and review recent literature. We report a case of a 38-year-old woman with history of asthma, presented to our department with acute inspiratory dyspnea that required an emergency tracheotomy. Physical examination revealed a large anterior cervical mass without any lymphadenopathy suspecting thyroid origin. Cervical Computed Scan showed a tumor process between the thyroid lobe, the left edge of the subglottic area and first tracheal rings filling all the lumen, discussing either a laryngo-tracheal or thyroid origin. The patient underwent a panendoscopy under general anesthesia that confirmed a subglottic extension of the tumor and multiples biopsies showed a malignant salivary origin of the mass. After multidisciplinary discussion, the patient underwent total laryngectomy and thyroidectomy with bilateral selective neck dissections (levels II- IV). Anatomopathological examination confirmed the laryngeal location of Adenoid Cystic Carcinoma classified pT4aN0R0. Adjuvant radiation therapy was indicated. In our knowledge, only 10 cases were reported in the literature with this unusual presentation. Moreover, the case we report is in the subglottic floor without invasion of neither vocal cords nor trachea. Total laryngectomy with neck dissection remains the recommended therapeutic procedure for locally advanced ACCL. Adverse features such as close or positive margins, T3-4, intermediate or high grade neural and perineural spread, lymphatic or vascular invasion or lymph node metastases should indicate adjuvant treatment to improve the outcome. The lack of randomized multicentric study, implies the management of ACCL by skilled multidisciplinary team, to suggest adequate personalized treatment.

[Gastrointestinal Stromal Tumors "GIST": status and news through our experience on 54 cases and review of literature]

Les Tumeurs Stromales Gastro-intestinales « GIST » sont une forme très rare de cancers du tube digestif appartenant à la famille des sarcomes. Le but de ce travail est d'établir le profil épidémiologique et évolutif ainsi que les difficultés diagnostique et thérapeutique de cette pathologie maligne prise en charge dans un pays en développement. Une Etude rétrospective étalée sur 8 ans de Janvier 2002 à Mars 2010, a été mené au Service de Radiothérapie et d'Oncologie du CHU de Casablanca (Maroc) ayant colligée 54 cas de tumeurs stromales gastro-intestinales. L'âge moyen de nos patients était de 55 ans. Le délai moyen d'évolution était de 11 mois (0-72 mois). La biopsie a permis de confirmer le diagnostic dans 14 cas et la chirurgie dans 40 cas. La principale forme histologique était fusiforme (92,6%). Les GIST dans notre série avaient une taille tumorale moyenne de 12,5 cm avec un C-Kit positif dans 52 cas. Le risque évolutif a pu être établi dans 47 cas dont 39 avaient un risque élevé. La chirurgie était le principal traitement des patients de notre sérieAprès un recul moyen de 31 mois, la moitié des patients évaluables de notre série (n=19) est en rémission complète maintenue, le tiers (n=13) est décédé alors que le quart (n=8) présente une récidive locale et /ou métastatique. Quoique les recommandations soient éditées pour la prise en charge de ces tumeurs, ces dernières soulèvent encore de nombreux problèmes aussi bien diagnostiques que thérapeutiques dans notre contexte.

Long-Term Correction of Albumin Levels in the Nagase Analbuminemic Rat: Repopulation of the Liver by Transplanted Normal Hepatocytes under a Regeneration Response

Numerous studies have reported successful transplantation of hepatocytes with demonstration of function. However, none have shown long-term correction of a liver-related metabolic defect. Male Nagase analbuminemic rats, immunosuppressed with cyclosporin-A, were transplanted with normal hepatocytes (2 × 107 cells/rat) isolated from allogeneic male Sprague–Dawley rat donors. Hepatocytes were selectively transplanted via the portal vein tributary into the posterior liver lobes of Nagase analbuminemic rats. Following 2 wk, to allow engraftment, selected transplanted rats (Group I) were reoperated and the portal venous branch supplying the anterior liver lobes was permanently ligated, resulting in their atrophy and induction of regeneration in the residual transplant-bearing lobes. Control rats consisted of: Group II—transplanted with normal hepatocytes without portal branch ligation; Group III—transplanted with analbuminemic hepatocytes with portal branch ligation; and Group IV—nontransplanted analbuminemic rats with portal branch ligation. The experimental period extended to 3 mo posttransplantation. All rats transplanted with normal hepatocytes demonstrated a significant elevation in serum albumin levels (ELISA). Group I rats had dramatic elevations in serum albumin to near normal levels (1.78 ± 0.20 g/dl), and maintained these levels until the end of the experiment Albumin levels in Group II rats reached 0.26 ± 0.07 g/dl (p < 0.001), whereas Group III and IV rats showed no changes in serum albumin levels throughout the experiment Immunohistology of liver tissue obtained from Group I rats, demonstrated large numbers (22.6 ± 7.5%) of albumin-positive hepatocytes populating the recipient liver. This is the first report of near-total and sustained correction of a genetic defect in liver function in an experimental animal model following allogeneic hepatocyte transplantation.

[Ameloblastoma of the maxillary sinus treated with radiation therapy]

Ameloblastoma is a benign aggressive odontogenic tumor which requires early diagnosis and appropriate treatment. It commonly affects the mandible and radical surgery is the gold standard treatment. We report the case of a patient with ameloblastoma in extremely advanced phase affecting the maxillary sinus who was treated with intensity modulated conformal radiation therapy. Patient's evolution was marked by complete remission maintained after 24 months follow-up. Maxillary ameloblastoma is not well documented in the literature. It is usually diagnosed at the later stage when optimal surgery cannot be performed. This case study aimed to demonstrate that radiation therapy is a real therapeutic alternative in the treatment of advanced and inoperable forms of ameloblastoma.

[Mucinous carcinoma of the breast: Clinical, biological and evolutive profile]

PURPOSE

Mucinous carcinoma of the breast accounts for 1 to 4% of all breast cancer. There are two histological subtypes: mixed mucinous carcinoma, where the ductal carcinoma is associated with the colloid component, and pure mucinous carcinoma, with a favorable prognosis, where the mucus surrounds the tumour tissue and constitutes a mechanical barrier limiting cell invasion and making this form less aggressive. Our study aimed to determine retrospectively the main epidemiological, clinical, biological, and therapeutic features, as well as the prognosis of this rare form of breast carcinoma.

MATERIALS AND METHODS

The authors report 32 cases of mucinous carcinoma of the breast diagnosed in Mohammed-VI centre for cancer treatment in Casablanca.

RESULTS

The average tumour size was 4.5cm (0.5-7cm). We found ten positive lymph node dissections, seven of them were of mixed mucinous carcinoma with a tumour size ranging between 4 and 7cm. Mucinous carcinoma was pure in 16 cases, mixed in 14 and a neuroendocrine differentiation was found in two cases. Most tumours were of an intermediate histological grade (n=19) with positive hormonal receptors (68%). After a mean follow-up of 30 months, complete remission was maintained in 92% of evaluable patients.

CONCLUSION

Mucinous carcinoma is a rare type of breast cancer, with a favourable prognosis for the pure form.

[Squamous cell carcinoma of the penis]

Penile tumors are the rarest male urogenital tract tumors (1%). Squamous cell carcinoma is the most common histologic type (95%). Radical surgical excision, though often mutilating, remains the best treatment for localized stages, in terms of local control (6% local recurrence). There are other therapeutic weapons and their possible indications should be adapted to the locoregional extension and at a distance from the primary tumor. We report the case of Mr AS aged 61, without particular pathological antecedents, who consulted, 6 years before, for an ulcerated burgeoning in the anterior surface of the penile bleeding on contact, which extended along the penis, without involving the glans penis. Evolution was marked by tumor progression with extension to the anterior pelvic wall. The patient went into a critical state of hemorrhagic shock. After stabilizing the hemodynamic status, a biopsy of the penis lesion confirmed the diagnosis of well-differentiated squamous cell carcinoma. An evaluation of the extent of loco-regional recurrence and distant metastasis showed pulmonary micronodules in the right lung. The case was discussed at the Multidisciplinary Consultative Meeting and patient was deemed inoperable and offered palliative chemotherapy. The prognosis of advanced stages of penis cancer is reserved; their frequency in our context is related to the modesty of patients, which explains the causes of delay in medical examination. Only socio-cultural awareness allows early diagnosis and, therefore, a better prognosis.

Surface-induced spin state locking of the [Fe(H2B(pz)2)2(bipy)] spin crossover complex

Temperature- and coverage-dependent studies of the Au(1 1 1)-supported spin crossover Fe(II) complex (SCO) of the type [Fe(H2B(pz)2)2(bipy)] with a suite of surface-sensitive spectroscopy and microscopy tools show that the substrate inhibits thermally induced transitions of the molecular spin state, so that both high-spin and low-spin states are preserved far beyond the spin transition temperature of free molecules. Scanning tunneling microscopy confirms that [Fe(H2B(pz)2)2(bipy)] grows as ordered, molecular bilayer islands at sub-monolayer coverage and as disordered film at higher coverage. The temperature dependence of the electronic structure suggest that the SCO films exhibit a mixture of spin states at room temperature, but upon cooling below the spin crossover transition the film spin state is best described as a mix of high-spin and low-spin state molecules of a ratio that is constant. This locking of the spin state is most likely the result of a substrate-induced conformational change of the interfacial molecules, but it is estimated that also the intra-atomic electron-electron Coulomb correlation energy, or Hubbard correlation energy U, could be an additional contributing factor.

Metal nanocluster light-emitting devices with suppressed parasitic emission and improved efficiency: exploring the impact of photophysical properties

Here we investigate the photophysical properties of Au(0)@Au(i)-thiolate nanoclusters by controlling the degree of aggregation, and measure electrochemical energy levels to design a metal nanocluster-based thin film LED (MNC-LED) structure. These efforts allow us to implement MNC-LEDs with luminance exceeding 40 cd m(-2) and external quantum efficiency exceeding 0.1% with clearly visible orange emission. It is also demonstrated that by varying the sizes of nanoclusters, the electroluminescence spectrum of the device can be tuned to the infrared emission, indicating the possibility of exploiting metal nanocluster emitters for use over a wide spectral range.

Dosimetric evaluation of 3-D conformal and intensity-modulated radiotherapy for breast cancer after conservative surgery

BACKGROUND

Breast cancers are becoming more frequently diagnosed at early stages with improved long term outcomes. Late normal tissue complications induced by radiotherapy must be avoided with new breast radiotherapy techniques being developed. The aim of the study was to compare dosimetric parameters of planning target volume (PTV) and organs at risk between conformal (CRT) and intensity-modulated radiation therapy (IMRT) after breast-conserving surgery.

MATERIALS AND METHODS

A total of 20 patients with early stage left breast cancer received adjuvant radiotherapy after conservative surgery, 10 by 3D-CRT and 10 by IMRT, with a dose of 50 Gy in 25 sessions. Plans were compared according to dose-volume histogram analyses in terms of PTV homogeneity and conformity indices as well as organs at risk dose and volume parameters.

RESULTS

The HI and CI of PTV showed no difference between 3D-CRT and IMRT, V95 gave 9.8% coverage for 3D-CRT versus 99% for IMRT, V107 volumes were recorded 11% and 1.3%, respectively. Tangential beam IMRT increased volume of ipsilateral lung V5 average of 90%, ipsilateral V20 lung volume was 13%, 19% with IMRT and 3D-CRT respectively. Patients treated with IMRT, heart volume encompassed by 60% isodose (30 Gy) reduced by average 42% (4% versus 7% with 3D-CRT), mean heart dose by average 35% (495 cGy versus 1400 cGy with 3D-CRT). In IMRT minimal heart dose average is 356 cGy versus 90 cGy in 3D-CRT.

CONCLUSIONS

IMRT reduces irradiated volumes of heart and ipsilateral lung in high-dose areas but increases irradiated volumes in low-dose areas in breast cancer patients treated on the left side.

Lemierre's syndrome: a serious complication of a routine dental procedure

Lemierre's syndrome is the clinical presentation characterized by oropharyngeal or tonsillar infection, anaerobic septicaemia often with distant septic emboli, and clinical or radiological evidence of thrombosis of the internal jugular vein. We report a case of Lemierre's syndrome in a 44-year-old type II diabetic male. This case is unique for two reasons. Firstly, we believe it is the first reported iatrogenic case following a routine dental procedure. Secondly, the internal jugular vein thrombosis was found to occur on the contralateral side to the primary infection.

[Stewart-Treves syndrome complicating chronic idiopathic lymphedema]

Le syndrome de Stewart-Treves (SST) est une entité rare, correspondant à un angiosarcome cutané compliquant un lymphoedème chronique. Il est de mauvais pronostic. Stewart et Treves ont rapportés en 1948, les premiers cas d'angiosarcome secondaire à un traitement du cancer du sein. Ce terme s'est généralisé pour regrouper l'ensemble des cas de lymphangiosarcome sur lymphoedème d'origine congénital héréditaire ou non héréditaire, post-traumatique ou post-infectieux. Le SST sur un lymphoedème idiopathique reste exceptionnel. Nous rapportons le cas rare d'une patiente présentant un lymphoedème chronique primitif idiopathique des quatre membres évoluant depuis l'adolescence et qui a développé un SST du membre supérieur droit. Elle a subi une amputation à mi- bras vu le caractère très évolué de la tumeur

Chronic inflammatory autoimmune disorders and atherosclerosis

Rheumatoid arthritis (RA), periodontal disease (PD), and coronary artery disease (CAD) are common chronic inflammatory diseases. RA is associated with accelerated vascular risk resulting in an increased prevalence of CAD with attendant early mortality and excess morbidity. RA and PD have a common pathobiology. Accordingly, the aim of this study was to evaluate the association between RA, PD, and CAD and the influence of systemic inflammatory factors. A total of 100 active RA patients of which 50 had established CAD and 50 had no CAD were assessed for PD. All subjects underwent a clinical, cardiac, dental, laboratory, and radiological evaluation. Blood samples were obtained and the level of high-sensitivity C-reactive protein (hs-CRP), total white blood counts (WBC), erythrocyte sedimentation rate (ESR), fibrinogen and tumor necrosis alpha (TNF-alpha), total cholesterol (TC), and high-density lipoprotein (HDL) were assayed. The findings of this study demonstrated an association between RA, PD, and CAD. The RA patients with CAD had significantly more PD than RA patients without CAD, P < 0.001. The inflammatory markers hs-CRP, ESR, WBC, fibrinogen, and TNF-alpha were raised in all patients but were significantly higher in RA patients with CAD who also had PD, that is, in those with more inflammatory disease burden. HDL levels were lower in RA patients with CAD when compared to RA patients without CAD, P < 0.005. Evidence from this study shows an association between RA, PD, CAD, and systemic levels of the inflammatory mediators. The implication is that inflammation may be the central link between the chronic inflammatory autoimmune disorders and atherosclerosis.

Rheumatoid arthritis, periodontal disease and coronary artery disease

Rheumatoid arthritis (RA), periodontal disease (PD), and coronary artery disease (CAD) are common chronic inflammatory diseases. RA is associated with accelerated vascular risk resulting in an increased prevalence of CAD with attendant early mortality and excess morbidity. RA and PD have a common pathobiology. Accordingly, the aim of this study was to evaluate the association between RA, PD, and CAD and the influence of systemic inflammatory factors. A total of 100 active RA patients of which 50 had established CAD and 50 had no CAD were assessed for PD. All subjects underwent a clinical, cardiac, dental, laboratory, and radiological evaluation. Blood samples were obtained, and the level of high sensitivity C-reactive protein (hs-CRP), total white blood counts (WBC), erythrocyte sedimentation rate (ESR), fibrinogen and tumor necrosis factor (TNF) alpha, total cholesterol (TC), and high density lipoprotein (HDL) were assayed. The findings of this study demonstrated an association between RA, PD, and CAD. The RA patients with CAD had significantly more PD than RA patients without CAD. The inflammatory markers, hsCRP, ESR, WBC, fibrinogen, and TNF-alpha, were raised in all patients but were significantly higher in RA patients with CAD who also had PD. HDL levels were lower in RA patients with CAD when compared to RA patients without CAD. Evidence from this study shows an association between RA, PD, CAD, and systemic levels of the inflammatory mediators. The implication is that inflammation may be the central link between the chronic inflammatory, autoimmune disorders, and atherosclerosis.

E-MSD: improving data deposition and structure quality

The Macromolecular Structure Database (MSD) (http://www.ebi.ac.uk/msd/) [H. Boutselakis, D. Dimitropoulos, J. Fillon, A. Golovin, K. Henrick, A. Hussain, J. Ionides, M. John, P. A. Keller, E. Krissinel et al. (2003) E-MSD: the European Bioinformatics Institute Macromolecular Structure Database. Nucleic Acids Res., 31, 458-462.] group is one of the three partners in the worldwide Protein DataBank (wwPDB), the consortium entrusted with the collation, maintenance and distribution of the global repository of macromolecular structure data [H. Berman, K. Henrick and H. Nakamura (2003) Announcing the worldwide Protein Data Bank. Nature Struct. Biol., 10, 980.]. Since its inception, the MSD group has worked with partners around the world to improve the quality of PDB data, through a clean up programme that addresses inconsistencies and inaccuracies in the legacy archive. The improvements in data quality in the legacy archive have been achieved largely through the creation of a unified data archive, in the form of a relational database that stores all of the data in the wwPDB. The three partners are working towards improving the tools and methods for the deposition of new data by the community at large. The implementation of the MSD database, together with the parallel development of improved tools and methodologies for data harvesting, validation and archival, has lead to significant improvements in the quality of data that enters the archive. Through this and related projects in the NMR and EM realms the MSD continues to improve the quality of publicly available structural data.

E-MSD: an integrated data resource for bioinformatics

The Macromolecular Structure Database (MSD) group (http://www.ebi.ac.uk/msd/) continues to enhance the quality and consistency of macromolecular structure data in the Protein Data Bank (PDB) and to work towards the integration of various bioinformatics data resources. We have implemented a simple form-based interface that allows users to query the MSD directly. The MSD 'atlas pages' show all of the information in the MSD for a particular PDB entry. The group has designed new search interfaces aimed at specific areas of interest, such as the environment of ligands and the secondary structures of proteins. We have also implemented a novel search interface that begins to integrate separate MSD search services in a single graphical tool. We have worked closely with collaborators to build a new visualization tool that can present both structure and sequence data in a unified interface, and this data viewer is now used throughout the MSD services for the visualization and presentation of search results. Examples showcasing the functionality and power of these tools are available from tutorial webpages (http://www. ebi.ac.uk/msd-srv/docs/roadshow_tutorial/).

E-MSD: the European Bioinformatics Institute Macromolecular Structure Database

The E-MSD macromolecular structure relational database (http://www.ebi.ac.uk/msd) is designed to be a single access point for protein and nucleic acid structures and related information. The database is derived from Protein Data Bank (PDB) entries. Relational database technologies are used in a comprehensive cleaning procedure to ensure data uniformity across the whole archive. The search database contains an extensive set of derived properties, goodness-of-fit indicators, and links to other EBI databases including InterPro, GO, and SWISS-PROT, together with links to SCOP, CATH, PFAM and PROSITE. A generic search interface is available, coupled with a fast secondary structure domain search tool.

From molecular activities and processes to biological function

This paper describes how biological function can be represented in terms of molecular activities and processes. It presents several key features of a data model that is based on a conceptual description of the network of interactions between molecular entities within the cell and between cells. This model is implemented in the aMAZE database that presently deals with information on metabolic pathways, gene regulation, sub- or supracellular locations, and transport. It is shown that this model constitutes a useful generalisation of data representations currently implemented in metabolic pathway databases, and that it can furthermore include multiple schemes for categorising and classifying molecular entities, activities, processes and localisations. In particular, we highlight the flexibility offered by our system in representing multiple molecular activities and their control, in viewing biological function at different levels of resolution and in updating this view as our knowledge evolves.

Representing and analysing molecular and cellular function using the computer

Determining the biological function of a myriad of genes, and understanding how they interact to yield a living cell, is the major challenge of the post genome-sequencing era. The complexity of biological systems is such that this cannot be envisaged without the help of powerful computer systems capable of representing and analysing the intricate networks of physical and functional interactions between the different cellular components. In this review we try to provide the reader with an appreciation of where we stand in this regard. We discuss some of the inherent problems in describing the different facets of biological function, give an overview of how information on function is currently represented in the major biological databases, and describe different systems for organising and categorising the functions of gene products. In a second part, we present a new general data model, currently under development, which describes information on molecular function and cellular processes in a rigorous manner. The model is capable of representing a large variety of biochemical processes, including metabolic pathways, regulation of gene expression and signal transduction. It also incorporates taxonomies for categorising molecular entities, interactions and processes, and it offers means of viewing the information at different levels of resolution, and dealing with incomplete knowledge. The data model has been implemented in the database on protein function and cellular processes 'aMAZE' (http://www.ebi.ac.uk/research/pfbp/), which presently covers metabolic pathways and their regulation. Several tools for querying, displaying, and performing analyses on such pathways are briefly described in order to illustrate the practical applications enabled by the model.

Long-term correction of albumin levels in the Nagase analbuminemic rat: repopulation of the liver by transplanted normal hepatocytes under a regeneration response

Numerous studies have reported successful transplantation of hepatocytes with demonstration of function. However, none have shown long-term correction of a liver-related metabolic defect. Male Nagase analbuminemic rats, immunosuppressed with cyclosporin-A, were transplanted with normal hepatocytes (2 x 10(7) cells/rat) isolated from allogeneic male Sprague-Dawley rat donors. Hepatocytes were selectively transplanted via the portal vein tributary into the posterior liver lobes of Nagase analbuminemic rats. Following 2 wk, to allow engraftment, selected transplanted rats (Group I) were reoperated and the portal venous branch supplying the anterior liver lobes was permanently ligated, resulting in their atrophy and induction of regeneration in the residual transplant-bearing lobes. Control rats consisted of: Group II-transplanted with normal hepatocytes without portal branch ligation; Group III-transplanted with analbuminemic hepatocytes with portal branch ligation; and Group IV-nontransplanted analbuminemic rats with portal branch ligation. The experimental period extended to 3 mo posttransplantation. All rats transplanted with normal hepatocytes demonstrated a significant elevation in serum albumin levels (ELISA). Group I rats had dramatic elevations in serum albumin to near normal levels (1.78 +/- 0.20 g/dl), and maintained these levels until the end of the experiment. Albumin levels in Group II rats reached 0.26 +/- 0.07 g/dl (p < 0.001), whereas Group III and IV rats showed no changes in serum albumin levels throughout the experiment. Immunohistology of liver tissue obtained from Group I rats, demonstrated large numbers (22.6 +/- 7.5%) of albumin-positive hepatocytes populating the recipient liver. This is the first report of near-total and sustained correction of a genetic defect in liver function in an experimental animal model following allogeneic hepatocyte transplantation.

Masking as a mechanism for evaporative loss of trace analyte, especially after solid-phase extraction

Using a Pasteur pipette plugged with silanized glass wool and packed with C18-silica particles, we attempted to remove K2CO3 from an aqueous acetonitrile solution. In spite of extensive washing of the column with water after the sample was applied, elution with acetonitrile followed by evaporation gave a visible, white residue. It was found that the residue was derived from both the sample and the packing, including particles from the latter. Substitution of a plastic column/polyethylene frit for the Pasteur pipette/glass wool gave a more consistent residue, apparently because this improved the retention of particles. Subsequent experiments were conducted in the plastic hardware. The amount of the residue was observed to vary as much as 19-fold when C18-silica particles were tested from different manufacturers, and the residue could be reduced in amount as much as 9-fold when a column was prepared in the laboratory vs. the use of a comparable, pre-packed column. The water itself contributed some of the residue: even the "purest" water routinely available left a visible residue when 1.0 ml was appropriately evaporated (e.g. on Saran Wrap in a microwave oven). The recovery of an arbitrary trace analyte and internal standard (pentafluorobenzylated nucleobases at the low pg level) was 32% less when they were evaporated in acetonitrile that had been passed through an acetonitrile and water-washed cartridge containing C18-Si vs. evaporation in untreated acetonitrile. Collectively these results reveal that an evaporation can risk some loss of an analyte from masking by even subtle solvent contaminants.(ABSTRACT TRUNCATED AT 250 WORDS)

Galaxies, Human Eyes, and Artificial Neural Networks

The quantitative morphological classification of galaxies is important for understanding the origin of type frequency and correlations with environment. However, galaxy morphological classification is still mainly done visually by dedicated individuals, in the spirit of Hubble's original scheme and its modifications. The rapid increase in data on galaxy images at low and high redshift calls for a re-examination of the classification schemes and for automatic methods. Here are shown results from a systematic comparison of the dispersion among human experts classifying a uniformly selected sample of more than 800 digitized galaxy images. These galaxy images were then classified by six of the authors independently. The human classifications are compared with each other and with an automatic classification by an artificial neural network, which replicates the classification by a human expert to the same degree of agreement as that between two human experts.