Determination of the absolute intensity of the 1205 keV γ-ray emission from 91Y.

A radiochemically pure solution of 91Y was produced by the thermal neutron fission of 235U followed by successive chemical separations to remove fission product impurities. The gamma emission rate of the 91Y 1205 keV gamma was measured using multiple high purity germanium gamma spectrometers previously calibrated for counting efficiency using a certificated mixed nuclide gamma standard. The activity concentration of the 91Y was subsequently standardised by liquid scintillation counting. From the combination the activity concentration and gamma emission intensity, the absolute intensity of the 1205 keV gamma emission was derived as 0.2297(39)%. This data agrees within the quoted uncertainties with the absolute intensity of 0.26(4)% published in nuclear data sheets A=91 (Baglin, 2013), but reduces the uncertainty by an order of magnitude.

The high morbidity of blunt cerebrovascular injury in an unscreened population: more evidence of the need for mandatory screening protocols.

BACKGROUND: Blunt cerebrovascular injuries are rare injuries causing substantial morbidity and mortality. The appropriate screening methods and treatment options for these injuries are controversial. We examined our experience with these injuries at a community Level I Trauma center over a 51 month period. STUDY DESIGN: A retrospective review and analysis was done of all patients with the diagnosis of a blunt cerebrovascular injury during this period. RESULTS: Fourteen patients had blunt carotid injury (0.40%) and three had blunt vertebral injury (0.09%) out of 3,480 total blunt admissions. The overall incidence of blunt cerebrovascular injury was 0.49%. The most common associated injuries were to the head (59%) and chest (47%) regions. The overall mortality rate was 59% (10 of 17), with death occurring in 8 of 14 (57%) blunt carotid injury patients and 2 of 3 (67%) blunt vertebral injury patients. Eight of ten (80%) deaths were directly attributable to the blunt cerebrovascular injury. Median time until diagnosis was 12.5 h (range 1-336 h) for the entire group and 19.5 h for nonsurvivors. Diagnosis was delayed > 24h in 7 patients and > 48h in 5 patients. All five patients whose diagnoses were delayed > 48 h developed complications, and four (80%) of these patients died. CONCLUSIONS: Blunt cerebrovascular injury is uncommon, but lethal; particularly when the diagnosis is delayed. Aggressive screening protocols based on mechanism of injury, associated injuries, and physical findings are justified to minimize morbidity and mortality. Head and chest injuries may serve as markers for blunt cerebrovascular injury. Most deaths are directly attributable to the blunt cerebrovascular injury and not to associated injuries.

A potentially expanded role for enoxaparin in preventing venous thromboembolism in high risk blunt trauma patients.

BACKGROUND: Venous thromboembolism (VTE) is a frequent and potentially life-threatening complication after trauma. The purpose of this study is to investigate the effectiveness of enoxaparin in preventing deep venous thrombosis (DVT) and pulmonary embolism (PE) after injury in patients who are at high risk for developing VTE. STUDY DESIGN: A prospective single-cohort observational study was initiated for seriously injured blunt trauma patients admitted to a Level I trauma center during a 7-month period. Patients were eligible for the study if time hospitalized was > or = 72 hours, Injury Severity Score (ISS) was > or = 9, enoxaparin was started within 24 hours after admission, and one or more of the following high risk criteria were met: age > 50 years, ISS > or = 16, presence of a femoral vein catheter, Abbreviated Injury Score (AIS) > or = 3 for any body region, Glasgow Coma Scale (GCS) Score < or = 8, presence of major pelvic, femur, or tibia fracture, and presence of direct blunt mechanism venous injury. Patients with closed head injuries and nonoperatively treated solid abdominal organ injuries were also potential participants. The primary outcomes measured were thromboembolic events--either a documented lower extremity DVT by duplex color-flow doppler ultrasonography or a PE documented by rapid infusion CT pulmonary angiography or conventional pulmonary angiography. RESULTS: There were 118 patients enrolled in the study. Two patients (2%) developed DVT, one of which was proximal to the calf (95% confidence interval, 0% to 6%). Two of 12 patients (17%) with splenic injuries who received enoxaparin failed initial nonoperative management. There were no other bleeding complications, and no clinical evidence or documented episodes of PE. One patient died from multiple system organ failure. CONCLUSIONS: Enoxaparin is a practical and effective method for reducing the incidence of VTE in high risk, seriously injured patients. This study supports further investigation into the safety of enoxaparin prophylaxis in patients with closed head injuries and nonoperatively treated solid abdominal organ injuries.

Incidence of tracheal stenosis and other late complications after percutaneous tracheostomy.

OBJECTIVE: To determine the incidence of tracheal stenosis, voice and breathing changes, and stomal complications after percutaneous dilatational tracheostomy (PDT). METHODS: From December 1992 through June 1999, 420 critically ill patients underwent 422 PDTs. There were 340 (81%) long-term survivors, 100 (29%) of whom were interviewed and offered further evaluation by fiberoptic laryngotracheoscopy (FOL) and tracheal computed tomography (CT). Tracheal stenosis was defined as more than 10% tracheal narrowing on transaxial sections or coronal and sagittal reconstruction views. Forty-eight patients agreed to CT evaluation; 38 patients also underwent FOL. CT and FOL evaluations occurred at 30 +/- 25 (mean +/- standard deviation) months after PDT. RESULTS: Twenty-seven (27%) patients reported voice changes and 2 (2%) reported persistent severe hoarseness. Vocal cord abnormalities occurred in 4/38 (11%) patients, laryngeal granuloma in 1 (3%) patient, focal tracheal mucosal erythema in 2 (5%) patients, and severe tracheomalacia/stenosis in 1 (2.6%) patient. CT identified mild (11-25%) stenosis in 10 (21%) asymptomatic patients, moderate (26-50%) stenosis in 4 (8.3%) patients, 2 who were symptomatic, and severe (>50%) stenosis in 1 (2%) symptomatic patient. Ten patients (10%) reported persistent respiratory problems after tracheal decannulation, but only four agreed to be studied. Two patients had moderate stenosis, and one had severe stenosis. One patient's CT scan was normal. No long-term stomal complications were identified or reported. CONCLUSIONS: Subjective voice changes and tracheal abnormalities are common after endotracheal intubation followed by PDT. Long-term follow-up of critically ill patients identified a 31% rate of more than 10% tracheal stenosis after PDT. Symptomatic stenosis manifested by subjective respiratory symptoms after decannulation was found in 3 of 48 (6%) patients.

The safety of prolonging the use of central venous catheters: a prospective analysis of the effects of using antiseptic-bonded catheters with daily site care.

OBJECTIVE: To determine rates of catheter colonization and catheter-related bloodstream infection (CRBSI) when antiseptic-bonded central venous catheters (CVCs) and standardized daily site care are used with no predetermined interval for removal. DESIGN: Prospective observational study. SETTING: Two major trauma centers. PATIENTS: All trauma patients admitted to two major trauma centers that received a CVC from May 1996 through May 1998. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Catheters were semiquantitatively cultured to identify bacterial colonization and CRBSI. Monitored variables included total catheter days, anatomical site of catheter insertion, and area in hospital of catheter insertion. CVC tips and intracutaneous segments were semiquantitatively cultured. A total of 460 (92%) of 501 catheters placed in 324 trauma patients were evaluable, representing 95.5% of all catheter days during the study period. Rates of catheter colonization and CRBSI were 5% (5/1000 catheter days) and 1.5% (1.511000 catheter days), respectively. Subclavian catheters were in place longer than femoral or internal jugular catheters (p < .0001), but the colonization rate was significantly lower (p = .03; relative risk, 0.34; 95% confidence interval, 0.15-0.77). No differences in CRBSI rates among anatomical sites or between catheters used < or =14 days and those used >14 days were identified. CONCLUSION: Femoral and internal jugular antiseptic-bonded CVCs develop bacterial colonization earlier than subclavian CVCs. Subclavian antiseptic-bonded CVCs combined with standardized daily site care may be safely used >14 days in trauma patients.

Efficacy and validity of radiofrequency neurotomy for chronic lumbar zygapophysial joint pain.

STUDY DESIGN: A prospective audit. OBJECTIVE: To establish the efficacy of lumbar medial branch neurotomy under optimum conditions. SUMMARY OF BACKGROUND DATA: Previous reports of the efficacy of lumbar medial branch neurotomy have been confounded by poor patient selection, inaccurate surgical technique, and inadequate assessment of outcome. METHODS: Fifteen patients with chronic low back pain whose pain was relieved by controlled, diagnostic medial branch blocks of the lumbar zygapophysial joints, underwent lumbar medial branch neurotomy. Before surgery, all were evaluated by visual analog scale and a variety of validated measures of pain, disability, and treatment satisfaction. Electromyography of the multifidus muscle was performed before and after surgery to ensure accuracy of the neurotomy. All outcome measures were repeated at 6 weeks, and 3, 6, and 12 months after surgery. RESULTS: Some 60% of the patients obtained at least 90% relief of pain at 12 months, and 87% obtained at least 60% relief. Relief was associated with denervation of the multifidus in those segments in which the medial branches had been coagulated. Prelesion electrical stimulation of the medial branch nerve with measurement of impedance was not associated with outcome. CONCLUSIONS: Lumbar medial branch neurotomy is an effective means of reducing pain in patients carefully selected on the basis of controlled diagnostic blocks. Adequate coagulation of the target nerves can be achieved by carefully placing the electrode in correct position as judged radiologically. Electrical stimulation before lesioning is superfluous in assuring correct placement of the electrode.

Mechanisms and patterns of injuries related to large animals.

BACKGROUND: Injuries from encounters with large animals represent a significant health risk for rural communities. We evaluated our regional trauma centers' experience with large-animal injuries to determine whether certain mechanisms and patterns of injury predicted either major head/craniofacial or torso (chest/abdomen/pelvis) trauma. METHODS: The hospital courses of 145 patients with injuries related to large animals were reviewed retrospectively to determine patterns of injury, specific injury mechanisms, species-specific injuries, and predictors of multiple body region trauma. RESULTS: Seventy-nine patients (55%) were injured by horses, 47 patients (32%) by bulls, 16 patients (11%) by cows, and 3 patients (2%) by wild animal attacks. The predominant species-specific mechanisms of injury were falls (horses), tramplings (bulls), and kicks (cows). Brain/craniofacial injuries were most common from horse-related encounters (32%), whereas bull and cow encounters usually resulted in torso injuries (45% and 56%, respectively). Multiple body region injuries occurred in 32% of patients. Fractures of the upper extremities were more often associated with torso and head/craniofacial injuries (48%) than lower extremity injuries (17%) (p = 0.02). CONCLUSION: Large animal injuries frequently involve multiple body regions with species-specific mechanisms. Upper extremity injuries are associated with a significantly higher percentage of torso and head/craniofacial injuries, which may have implications for field triage.

Tyler asbestos workers: mortality experience in a cohort exposed to amosite.

OBJECTIVES: To examine the causes of death among 1130 former workers of a plant in Tyler, Texas dedicated to the manufacture of asbestos pipe insulation materials. This cohort is important and unusual because it used amosite as the only asbestiform mineral in the production process. High level exposure of such a specific type was documented through industrial hygiene surveys in the plant. METHODS: Deaths were ascertained through various sources including data tapes from the Texas Department of Health and the national death index files. As many death certificates as possible were secured (304/315) and cause of death assigned. After select exclusions, 222 death certificates were used in the analysis. Causes of death were compared with age, race, and sex specific mortalities for the United States population with a commercial software package (OCMAP Version 2.0). RESULTS: There was an excess of deaths from respiratory cancer including the bronchus, trachea, and lung (standardised mortality ratio (SMR) 277 with 95% confidence interval (95% CI) 193 to 385). Four pleural mesotheliomas and two peritoneal mesotheliomas were identified. The analysis also showed an increasing risk of respiratory malignancy with increased duration of exposure including a significant excess of total deaths from respiratory cancer with less than six months of work at the plant (SMR 268 with 95% CI 172 to 399). CONCLUSIONS: The importance of the cohort lies with the pure amosite exposure which took place in the plant and the extended period of latency which has followed. The death certificate analysis indicates the pathogenicity of amosite, the predominant commercial amphibole used in the United States. These data confirm a link between amosite asbestos and respiratory malignancy as well as mesothelioma.

Analysis of asbestos fiber burden in lung tissue from mesothelioma patients.

Mesothelioma is a rare neoplasm that occurs most frequently in individuals with previous asbestos exposure. Differences for risk of development of asbestos-related mesothelioma and lung cancer have been attributed to the various types of asbestos, as well as to the dimension of the inhaled fibers. In the present study, 55 individuals with the pathological diagnosis of mesothelioma were evaluated as to ferruginous body and fiber content in lung tissue. The procedures used in the analysis included tissue digestion and analysis of the collected material for ferruginous bodies by light microscopy and for uncoated fibers by analytical transmission electron microscopy. Forty-six of the samples had ferruginous body concentrations of over 1000/per gram dry weight of lung tissue. The majority of the cores of these ferruginous bodies were amosite. Likewise, the most common uncoated asbestos fiber in the tissue was amosite. Only a small percentage of each type of asbestos would have been visible by light microscopy or even potentially by electron microscopy if the magnification was not sufficient to detect those with thin (< 0.2 micron) diameters. The consistent finding in most of the cases was a considerable presence of asbestos, often of mixed types.

Progression of pleural and parenchymal disease on chest radiographs of workers exposed to amosite asbestos.

OBJECTIVES: To determine predictors of progression of pleural and parenchymal disease on the chest radiographs of workers exposed to a short term, intense exposure of amosite asbestos. METHODS: The first and last of a series of chest radiographs of 887 workers exposed to amosite was interpreted and coded according to International Labour Organisation (ILO) standards by two physicians. Significant predictors of disease progression were found by a linear stepwise regression analysis from among such variables as smoking history, latency (time since first exposure), duration and intensity of exposure, and cytology. RESULTS: Although most radiographs remained normal, some showed progression of disease with about twice as many patients with abnormalities on the last film. Various combinations of age, intensity of exposure, and time between films were significant predictors of pleural and parenchymal disease and progression of such disease. No predominance of one sided disease was noted. Cytology and smoking were unreliable predictors of disease. Most disease progression was minor, usually of less than two scoring categories. CONCLUSION: An intense, yet short, exposure to amosite asbestos can produce pleural and parenchymal changes on chest radiographs. The number of those affected roughly doubled over a period spanning 10 to 20 years after exposure. Age and intensity of exposure are the most important predictors of disease.

The value of medical history and physical examination in diagnosing sacroiliac joint pain.

STUDY DESIGN: This prospective study evaluated the diagnostic utility of historically accepted sacroiliac joint tests. A multidisciplinary expert panel recommended 12 of the "best" sacroiliac joint tests to be evaluated against a criterion standard of unequivocal gain relief after an intra-articular injection of local anesthetic into the sacroiliac joint. OBJECTIVES: To identify a single sacroiliac joint test or ensemble of test that are sufficiently useful in diagnosing sacroiliac joint disorders to be clinically valuable. SUMMARY OF BACKGROUND DATA: No previous research has been done to evaluate any physical test of sacroiliac joint pain against an accepted criterion standard. METHODS: Historical data was obtained, and the 12 tests were performed by two examiners on 85 patients who subsequently underwent sacroiliac joint blocks. Ninety percent or more relief was considered a positive response, and less then 90% relief was considered a negative response. RESULTS: There were 45 positive and 40 negative responses. No historical feature, none of the 12 sacroiliac joint tests, and no ensemble of these 12 tests demonstrated worthwhile diagnostic value. CONCLUSION: Sacroiliac joint pain is resistant to identification by the historical and physical examination data from tests evaluated in this study.

Motif identification neural design for rapid and sensitive protein family search.

A new method, the motif identification neural design (MOTIFIND), has been developed for rapid and sensitive protein family identification. The method is an extension of our previous gene classification artificial neural system and employs new designs to enhance the detection of distant relationships. The new designs include an n-gram term weighting algorithm for extracting local motif patterns, an enhanced n-gram method for extracting residues of long-range correlation, and integrated neural networks for combining global and motif sequence information. The system has been tested and compared with several existing methods using three protein families, the cytochrome c, cytochrome b and flavodoxin. Overall it achieves 100% sensitivity and > 99.6% specificity, an accuracy comparable to BLAST, but at a speed of approximately 20 times faster. The system is much more robust than the PROSITE search which is based on simple signature patterns. MOTIFIND also compares favorably with BLIMPS, the Hidden Markov Model and PROFILESEARCH in detecting fragmentary sequences lacking complete motif regions and in detecting distant relationships, especially for members of under-represented subgroups within a family. MOTIFIND may be generally applicable to other proteins and has the potential to become a full-scale database search and sequence analysis tool.

Motif identification neural design for rapid and sensitive protein family search.

The accelerated growth of the molecular sequencing data has generated a pressing need for advanced sequence annotation tools. This paper reports a new method, termed MOTIFIND (Motif Identification Neural Design), for rapid and sensitive protein family identification. The method is extended from our previous gene classification artificial neural system and employs two new designs to enhance the detection of distant relationships. These include an n-gram term weighting algorithm for extracting local motif patterns, and integrated neural networks for combining global and local sequence information. The system has been tested with three protein families of electron transferases, namely cytochrome c, cytochrome b and flavodoxin, with a 100% sensitivity and more than 99.6% specificity. The accuracy of MOTIFIND is comparable to the BLAST database search method, but its speed is more than 20 times faster. The system is much more robust than the PROSITE search which is based on simple signature patterns. MOTIFIND also compares favorably with the BLIMPS search of BLOCKS in detecting fragmentary sequences lacking complete motif regions. The method has the potential to become a full-scale database search and sequence analysis tool.

Beta-Carotene, vitamin A, and lung cancer chemoprevention: results of an intermediate endpoint study.

A randomized, placebo-controlled clinical trial of beta-carotene and retinol was conducted with 755 former asbestos workers as study subjects. The targeted endpoint for the intervention study was a reduction in the incidence and prevalence of sputum atypia. The dosage of 50 mg beta-carotene/d and 25,000 IU retinol/d on alternate days resulted significant increases in serum concentrations of both agents with no clinically significant toxicity. Skin yellowing was observed in approximately 35% of patients and may have contributed adversely to protocol adherence. Baseline analysis revealed that smoking and drinking were associated with lower concentrations of serum beta-carotene, even after dietary carotene intake was adjusted for (P < 0.0001). Baseline concentrations of retinol were apparently lowered by smoking (P < 0.002) and increased by drinking (P < 0.0001). Drinking and smoking also were significantly related to lower beta-carotene concentrations after supplementation (P < 0.001). No significant reduction in sputum atypia was observed after treatment.

Two biochemical markers effectively used to separate smokeless tobacco users from smokers and nonusers.

Data from asbestos workers were used to devise a cutpoint classifier to identify subjects as Nonuser (non-tobacco user), Smokeless (exclusive smokeless tobacco user), and Smoker (ignited tobacco user). In some clinical trials and smoking cessation programs, Smokeless should be separated from Smoker. One therefore needs a marker for smoke exposure, such as thiocyanate, since nicotine levels, as measured by cotinine, could be similar in both groups. Levels of cotinine (ng/mL) and thiocyanate (mumol/L) levels (mean +/- SD) were, respectively: 320.9 +/- 201.1 and 145.9 +/- 63.7 for the Smoker group; 339.1 +/- 327.5 and 32.0 +/- 16.9 for the Smokeless group; and 0.6 +/- 2.6 and 58.2 +/- 33.2 for the Nonuser group. For Nonuser, Smokeless, and Smoker, respectively, the self-reported status was 45.1%, 10.8%, and 44.1%, which was adjusted to 42.2%, 11.6%, and 46.2%; the classifier yielded sensitivities of 100%, 76.1%, and 92.2%; specificities of 96.1%, 97.6%, and 96.4%; and predictive values of 94.9%, 80.6%, and 95.6%. The classifier successfully identified Nonusers, separated Smokeless from Smoker, and determined the prevalence of false reports in our cohort.

Sputum cytology within and across laboratories. A reliability study.

A total of 11 cytotechnologists at sites in Texas (TX1, TX2), California (CA) and Arkansas (AR) were assessed for agreement of six-category diagnoses of sputum cytology slides prepared by the method of Saccomanno. For three observers at TX1 there was more agreement within observers (27-60%) than across observers (13-50%). Within-1 category intraobserver agreement underwent a twofold to threefold increase, to 77-93%; within-2 category agreement was 90-100%. Interobserver within-1 category agreement was 47-92%; within-2 category agreement was 83-100%. Agreement was significantly greater than chance (using kappa) in 69% of all intraobserver and interobserver pairings. Intralaboratory agreement was 40% for CA and 40-57% for TX2. Among pairings of the four sites, the range of interlaboratory agreement was 13-60% over several occasions. The overall range of agreement with the TX1 standard was 17-50% over observers/occasions. Within certain categories, outside agreement with the TX1 standard was 53-90% for normal, 39-80% for squamous metaplasia, 68-84% for mild atypia, 80-100% for moderate atypia and 93-100% for severe atypia or carcinoma. We conclude that agreement is acceptable for extreme atypia, but more training or refinement of the guidelines may be needed, if justified, to better differentiate the lowest categories. Good agreement appears to be as likely for observers with many years of overall experience as for those with high exposure to the Saccomanno method. For potential statistical analyses, the scale should probably be condensed into three to four categories to reduce extraneous variability.

Identifying disagreement in ordinal ratings within a fixed panel of cytotechnologists.

In many clinical settings, a fixed number of raters screen specimens with more than two ordinal outcomes (for example, mild, moderate, severe). A design is proposed that facilitates the measurement of both interrater and intrarater agreement and associated trends. Design deficiencies are discussed, as are the propriety and interpretation of some common indices of reliability and reproducibility. The concepts are illustrated with data from cytopathologic ratings for sputum light microscopy.

Initial clinical assessment of the comatose patient: cerebral malaria vs. meningitis.

One hundred twenty-one Liberian children were admitted in coma to the ELWA Hospital, Monrovia, Liberia. Admitting diagnoses, before lumbar puncture, were compared with discharge diagnoses. Ninety-four children were discharged with a final diagnosis of cerebral malaria and 27 with a diagnosis of meningitis. The admitting diagnosis was correct in 76.6% (72 of 94) of patients with cerebral malaria and 59.3% (16 of 27) of patients with meningitis. The cerebrospinal fluid leukocyte count was the single most significant factor in determining the correct diagnosis. Without the cerebrospinal fluid analysis, the discriminant accuracy (77%), i.e. definitive separation of the two illnesses, was comparable to the physician's admission diagnosis (73%). Other data contributing to the differential diagnosis of cerebral malaria and meningitis included the number of days of fever before admission, the presence or absence of nuchal rigidity, fontanelle fullness and peripheral blood malaria smear. Mortality rates for cerebral malaria and meningitis were 14.9 and 29.6%, respectively. These data suggest that physicians cannot reliably discriminate between cerebral malaria and meningitis without cerebrospinal fluid analysis.

Neural networks for molecular sequence classification.

A neural network classification method has been developed as an alternative approach to the search/organization problem of large molecular databases. Two artificial neural systems have been implemented on a Cray supercomputer for rapid protein/nucleic acid sequence classifications. The neural networks used are three-layered, feed-forward networks that employ back-propagation learning algorithm. The molecular sequences are encoded into neural input vectors by applying an n-gram hashing method or a SVD (singular value decomposition) method. Once trained with known sequences in the molecular databases, the neural system becomes an associative memory capable of classifying unknown sequences based on the class information embedded in its neural interconnections. The protein system, which classifies proteins into PIR (Protein Identification Resource) superfamilies, showed a 82% to a close to 100% sensitivity at a speed that is about an order of magnitude faster than other search methods. The pilot nucleic acid system, which classifies ribosomal RNA sequences according to phylogenetic groups, has achieved a 100% classification accuracy. The system could be used to reduce the database search time and help organize the molecular sequence databases. The tool is generally applicable to any databases that are organized according to family relationships.

Protein classification artificial neural system.

A neural network classification method is developed as an alternative approach to the large database search/organization problem. The system, termed Protein Classification Artificial Neural System (ProCANS), has been implemented on a Cray supercomputer for rapid superfamily classification of unknown proteins based on the information content of the neural interconnections. The system employs an n-gram hashing function that is similar to the k-tuple method for sequence encoding. A collection of modular back-propagation networks is used to store the large amount of sequence patterns. The system has been trained and tested with the first 2,148 of the 8,309 entries of the annotated Protein Identification Resource protein sequence database (release 29). The entries included the electron transfer proteins and the six enzyme groups (oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases), with a total of 620 superfamilies. After a total training time of seven Cray central processing unit (CPU) hours, the system has reached a predictive accuracy of 90%. The classification is fast (i.e., 0.1 Cray CPU second per sequence), as it only involves a forward-feeding through the networks. The classification time on a full-scale system embedded with all known superfamilies is estimated to be within 1 CPU second. Although the training time will grow linearly with the number of entries, the classification time is expected to remain low even if there is a 10-100-fold increase of sequence entries. The neural database, which consists of a set of weight matrices of the networks, together with the ProCANS software, can be ported to other computers and made available to the genome community. The rapid and accurate superfamily classification would be valuable to the organization of protein sequence databases and to the gene recognition in large sequencing projects.