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At least 937 records · Page 52Linked to original sources
PubMed1983

Activation of factor XII by dextran sulfate: the basis for an assay of factor XII.

A system was developed for studying the activation of factor XII (Hageman factor) in the presence of dextran sulfate (DS). Salient features of the system included low ionic strength (0.08), low concentration of factor XII (approximately 1/10,000 that in normal plasma), and an excess of exogenous prekallikrein (PK). In this system, factor XII was rapidly converted to the 80,000 molecular weight (mol wt) form of factor XIIa (alpha-factor-XIIa). Once formed, the factor XIIa converted PK to kallikrein at a rate that was proportional to the amount of factor XII originally present in the incubation mixture. This system was used to construct a simple sensitive assay for factor XII in plasma and other biologic samples. The kallikrein produced was measured spectrophotometrically with the chromogenic substrate (H-D-Pro-Phe-Arg-p-nitroanilide (S-2302). This assay was shown to be independent of the high molecular weight kininogen and the PK content of the sample being analyzed. The measurements obtained were consistent with fundamental enzymologic principles and, if desired, could be processed with a simple calculator program to achieve linear standard curves. When applied to the quantitation of factor XII in plasma, the assay yielded values in close agreement with those determined by coagulant assay or by radial immunodiffusion.

Dextran Sulfate↗
PubMed1993

Fatty acid composition of human milk triglyceride species. Possible consequences for optimal structures of infant formula triglycerides.

Human milk triglycerides (TGs) were separated into 14 fractions by silver ion high-performance liquid chromatography (HPLC) with light-scattering detection (LSD). Subsequent fractionation by reversed-phase HPLC-LSD resulted in 75 subfractions. The major 48 were analysed by gas chromatography for their intact TG and fatty acid (FA) compositions. Using a constrained non-linear optimization computer program, the FA compositions and abundances of 170 different TG combinations were calculated. The major two, 16:0/18:1/18:1 (11.8 mol%) and 16:0/18:1/18:2 (10.0 mol%), were almost twice as abundant as expected from random FA distribution. The apolarities of 16:0 and 18:0 seem to be modulated by unsaturated FAs (18:1, 18:2) or medium-chain FAs (MCFAs; 8:0-12:0). MCFAs were present in 19 mol%. Of these, 7.2 mol% are likely to harbour stereospecific structures with an MCFA at sn-3, 16:0 or 14:0 at sn-2, and 18:1 or 18:2 at sn-1. These structures are excellent substrates for lingual and gastric lipases, producing products that assist in duodenal TG lipolysis.

Chromatography, Gas↗
PubMed1977

Evaluation with the centrifugal fast analyzer of a chemical activation procedure for creatine kinase MB isoenzyme.

The differential activation method for the determination of the "myocardial" isoenzyme of creatine kinase (MB) is based on the computed difference in activity of serum aliquots activated by the combination of dithiothreitol and glutathione (skeletal plus myocardial creatine kinase) and by glutathione alone (skeletal creatine kinase). The unique ability of the Centrifugal Fast Analyzer to perform analyses in parallel is used to precisely measure (CV = 0.1-1.5%) the activity of the two chemically activated aliquots. Statistical considerations concerning the reliability of this difference estimation are discussed with respect to both the precision of the rate measurements and to the relative amount of isoenzyme MB present. Another potential source of error in the analysis of the two differently activated aliquots, namely variation in lag phases, is circumvented by use of a linear-search FOCAL software package. This program searches the data for a linear segment of maximum slope, automatically rejecting those data that appear in lag or depletion regions of the curve representing the progress of the reaction. Correspondence of the results obtained with those of comparison techniques (chromatography and electrophoresis) are discussed.

Centrifugation↗
PubMed1996

[An attempt to evaluate prognosis in cases of metastasis from laryngeal and hypopharyngeal carcinoma to cervical lymph nodes].

The objective of the paper was the retrospective evaluation of oncological results after dissection radical (RND), modified (MND) and selective (SND) on cervical lymph nodes in laryngeal and hypopharyngeal carcinoma. On the basis of obtained study results, an answer was sought whether and what prognostic factors in metastases to the regional cervical lymph nodes should influence the choice of therapeutic method, and the survival. The study material comprised 986 patients treated during the period 1970-1991 in the Department of Otolaryngology-PAM in Szczecin due to laryngeal and hypopharyngeal carcinoma. In this group, apart from treating the primary changes, the cervical lymph nodes were operated on (Neck Dissection-ND). Data concerning the patients were obtained from: a/ case histories, b/ follow-up, c/ correspondence, d/ USC data. Clinical status of cervical lymph nodes, their histopathological state were assessed postoperatively. The patients' survival period after the treatment of carcinoma was estimated too. The occurrence of neoplastic disease recurrence in cervical lymph nodes was also taken into consideration. All data were collected in Personal Computer memory IBC (PC 386). In processing the data use was made of calculating and data base program Medikus. A linear regression model was elaborated for investigating the degree to which certain factors influence the appearance of nodal recurrence. Hierarchy was established for the factors whose influence on the occurrence of recurrence was the strongest. It becomes apparent from the accomplished studies that metastases to the regional cervical lymph nodes occurred most frequently in hypopharyngeal cancers (81.6%). The clinical assessment is burdened with an error claiming 31% of discrepancy as compared to results of histopathological examination (Tab. 3). Occult metastases were recorded in hypopharyngeal carcinoma about 20%, and in glottic one about 13%. It was revealed that the presence of metastases in lymph nodes, an increase affecting the stage of pT and pN reduced the chances of survival in a significant manner (Tab. 7 and 8). The greatest influence on the appearance of nodal recurrence was exerted by the following factors: number of metastatic nodes, size of nodes, component N, mode of treatment. It has been disclosed that the risk of nodal recurrence increases sixfold with the rise of factor N, twofold with the rise of the number of metastatic nodes, and 1,6 fold when the size of nodes increases by 1 cm. No differences were observed in the percentages of survivals following the operative treatment RND and MND, with the stage being N1-2 (Fig. 1). Radiotherapy applied after MND and RND failed to exert any meaningful positive influence on the overall percentage of survivals (Tab. 4). As compared with therapeutic dissection, better oncological results, scored after prophylactic removal of cervical lymphatic system, provide the basis for elective performance of prophylactic procedures in hypopharyngeal and laryngeal carcinomata.

Adolescent↗
PubMed2006

Estimating linear cortical magnification in human primary visual cortex via dynamic programming.

Human primary visual cortex is organized retinotopically, with adjacent locations in cortex representing adjacent locations on the retina. The spatial sampling in cortex is highly nonuniform: the amount of cortex devoted to a unit area of retina decreases with increasing retinal eccentricity. This sampling property can be quantified by the linear cortical magnification factor, which is expressed in terms of millimeters of cortex per degree of visual angle. In this paper, we present a new method using dynamic programming and fMRI retinotopic eccentricity mapping to estimate the linear cortical magnification factor in human primary visual cortex (V1). We localized cortical activity while subjects viewed each of seven stationary contrast- reversing radial checkerboard rings of equal thickness that tiled the visual field from 1.62 to 12.96 degrees of eccentricity. Imaging data from all epochs of each ring were contrasted with data from fixation epochs on a subject-by-subject basis. The resulting t statistic maps were then superimposed on a local coordinate system constructed from the gray/white matter boundary surface of each individual subject's occipital lobe, separately for each ring. Smoothed maps of functional activity on the cortical surface were constructed using orthonormal bases of the Laplace-Beltrami operator that incorporate the geometry of the cortical surface. This allowed us to stably track the ridge of maximum activation due to each ring via dynamic programming optimization over all possible paths on the cortical surface. We estimated the linear cortical magnification factor by calculating geodesic distances between activation ridges on the cortical surface in a population of five normal subjects. The reliability of these estimates was assessed by comparing results based on data from one quadrant to those based on data from the full hemifield along with a split-half reliability analysis.

Brain Mapping↗
PubMed1997

Molecular/cellular biology of the heat stress response and its role in agent-induced teratogenesis.

Available data indicate that heat shock proteins act as chaperones under non-stress conditions by assisting in: (1) the folding of newly synthesized proteins, (2) the intracellular translocation of proteins, and (3) the function of other proteins. As we gain additional information concerning cellular physiology, we may find that heat shock proteins play a key role in many additional cellular functions. When cells experience thermal or chemical stress, heat shock proteins take on a new role, conserved from bacteria to humans, of protecting cells from the detrimental effects of stress. This latter role takes on added significance for the embryo in which the developmental program must be read linearly, with little opportunity to cycle backward to complete a missed segment of the program. Although circumstantial evidence clearly implicates heat shock proteins in protecting embryos from thermal stress, definitive evidence is still lacking. The challenge for the future is to obtain such definitive data. Ideally, such information will lead to new therapeutic paradigms that will afford protection to the human embryo/fetus exposed to thermal/chemical stress.

Animals↗
PubMed1998

POLINA: detection and evaluation of single amino acid substitutions in protein superfamilies.

MOTIVATION AND RESULTS: An algorithm is described for the quick identification and evaluation of amino acid substitutions in multiple protein sequence alignment. The strategy is based on the calculation of a relative conservation index for an amino acid at each position of the alignment. The algorithm is implemented in the computer program POLINA (Protein Oriented LINear Analysis) which provides a summary of analysis in a format suitable for import into a graphing program. AVAILABILITY: A copy of source code is available upon request from the authors or can be downloaded via the WWW at http://www.geocities.com/Athens/4654/POLINA.h tml. CONTACT: slevin@aecom.yu.edu; bsatir@aecom.yu.edu

Algorithms↗
PubMed2000

Pathways to housing: supported housing for street-dwelling homeless individuals with psychiatric disabilities.

OBJECTIVE: This study examined the effectiveness of the Pathways to Housing supported housing program over a five-year period. Unlike most housing programs that offer services in a linear, step-by-step continuum, the Pathways program in New York City provides immediate access to independent scatter-site apartments for individuals with psychiatric disabilities who are homeless and living on the street. Support services are provided by a team that uses a modified assertive community treatment model. METHODS: Housing tenure for the Pathways sample of 242 individuals housed between January 1993 and September 1997 was compared with tenure for a citywide sample of 1, 600 persons who were housed through a linear residential treatment approach during the same period. Survival analyses examined housing tenure and controlled for differences in client characteristics before program entry. RESULTS: After five years, 88 percent of the program's tenants remained housed, whereas only 47 percent of the residents in the city's residential treatment system remained housed. When the analysis controlled for the effects of client characteristics, it showed that the supported housing program achieved better housing tenure than did the comparison group. CONCLUSIONS: The Pathways supported housing program provides a model for effectively housing individuals who are homeless and living on the streets. The program's housing retention rate over a five-year period challenges many widely held clinical assumptions about the relationship between the symptoms and the functional ability of an individual. Clients with severe psychiatric disabilities and addictions are capable of obtaining and maintaining independent housing when provided with the opportunity and necessary supports.

Adult↗
PubMed1984

Multidimensional curve fitting program for biological data.

A program written for use with the IBM-PC can be used to find least squares solutions to linearized multidimensional equations. The program is 'user-friendly' by requiring little from the user except to make decisions; most responses can be entered by a single keystroke. Once data are entered by the user, they can be repeatedly manipulated, graphed, and correlated. Many models relating data variables can be tried relatively easily, and best fit results found. Examples using respiratory mechanical data illustrate the ease of model comparisons.

Biometry↗
PubMed1983

[Computerized program for calculating the dose distribution generated by intracavitary linear sources of gamma radiation].

One can achieve a high precision in the dosing of a session of intracavitary radiotherapy by rapid computerization of the treatment time that is necessary for obtaining a certain dose in a pathological focus taking account of an actual location of radiation sources in the process of irradiation. The authors have developed an algorithm and drawn up a program for computer ES-1022 to calculate a dose rate in any point of an irradiated volume from the system of gamma-radiation sources oriented arbitrarily in space. As part of a hard- and soft ware dosimetric complex, the above program provides for the calculation of the treatment time by a set dose; the time is necessary for supplying this dose to a tumor focus taking account of an actual location of radiation sources during a session of irradiation. The whole computer procedure from the moment of obtaining necessary anatomo-topographic information in the form of two x-ray pictures up to the output of an irradiation session time value and other information into the alpha-numeric printer takes 3-5 min. The program makes it possible to calculate dose distribution in any preset plane (up to 4 planes at a time) of an irradiated volume.

Brachytherapy↗
PubMed2003

Resource allocation for control of infectious diseases in multiple independent populations: beyond cost-effectiveness analysis.

Traditional cost-effectiveness analysis (CEA) assumes that program costs and benefits scale linearly with investment-an unrealistic assumption for epidemic control programs. This paper combines epidemic modeling with optimization techniques to determine the optimal allocation of a limited resource for epidemic control among multiple noninteracting populations. We show that the optimal resource allocation depends on many factors including the size of each population, the state of the epidemic in each population before resources are allocated (e.g. infection prevalence and incidence), the length of the time horizon, and prevention program characteristics. We establish conditions that characterize the optimal solution in certain cases.

Communicable Disease Control↗
PubMed2000

HELANAL: a program to characterize helix geometry in proteins.

A detailed analysis of structural and position dependent characteristic features of helices will give a better understanding of the secondary structure formation in globular proteins. Here we describe an algorithm that quantifies the geometry of helices in proteins on the basis of their C alpha atoms alone. The Fortran program HELANAL can extract the helices from the PDB files and then characterises the overall geometry of each helix as being linear, curved or kinked, in terms of its local structural features, viz. local helical twist and rise, virtual torsion angle, local helix origins and bending angles between successive local helix axes. Even helices with large radius of curvature are unambiguously identified as being linear or curved. The program can also be used to differentiate a kinked helix and other motifs, such as helix-loop-helix or a helix-turn-helix (with a single residue linker) with the help of local bending angles. In addition to these, the program can also be used to characterise the helix start and end as well as other types of secondary structures.

Algorithms↗
PubMed1983

Data processing for radioimmunoassay standard curve using microcomputer: a new BASIC program for weighted logit-log transformation.

A new BASIC program of the weighted linear, quadratic and cubic logit-log regression methods for data processing of radioimmunoassay standard curve was developed using a microcomputer. Using this program, three regression analyses are calculated and the table for root mean square of residuals in each regression are shown for the selection of the regression method. The data of three radioimmunoassays of human pancreatic enzymes and pancreatic secretory trypsin inhibitor were examined by this program and compared with those processed by the four parameter logistic method. The weighted cubic logit-log regression showed better fit in radioimmunoassays of human pancreatic enzymes with larger molecular weights. The present program is useful and practicable for its simplicity and accuracy.

Computers↗
PubMed1996

Effect of vaccination against Aujeszky's disease compared with test and slaughter programme: epidemiological and economical evaluations.

In January 1990, a 6-year program was initiated to eliminate endemic Aujeszky's Disease virus (ADV) infection from the pig herds in an area of Northern Germany, bordering Southern Denmark, with intensive pig farming. In the first 3 years of the campaign, an intensive compulsory vaccination program, with glycoprotein I (gI)-deleted vaccines, of all pigs in the area was employed. Beginning in June 1990 and for the first 3 years of the project, approximately 200 herds randomly selected from all herds in the area, were serologically tested each quarter. In each farrow-to-feeder (FAFE), feeder-to-finish (FEFI) and farrow-to-finish (FAFI) herd, 20 female breeding pigs, 20 finishing pigs (> or = 50 kgs liveweight) and 10 female breeding pigs and 10 finishing pigs, respectively, were blood sampled. The sera were tested by the Herd-Check Anti-PRV(S) ELISA test (IDDEX Inc., ME). Sera positive to this test were examined by the HerdCheck Anti-ADV gI-ELISA test (IDDEX Inc., ME). Data on potentially confounding management factors were collected through a pilot-tested questionnaire, administered to farmers by 2 veterinarians who blood sampled the pigs. For fattening herds (FEFI and fattening sections of FAFI herds), the association between the odds of > or = 1 gI+ finishing pigs and the time between initiation of the program in the area and sampling date (a surrogate for the effect of the program) was modelled using ordinary logistic regression. The association between the odds of gI+ females in seropositive (> or = gI+ females) FAFE and FAFI herds and time since initiation of the program was investigated with logistic-binomial regression models. Results of the study show that the longer the period from the beginning of compulsory vaccination to the date the herd was sampled the lower the odds of gI+ fattening herds and gI+ female breeding pigs in herds of the area. The beneficial effect of mass vaccination on the reduction of ADV spread was accounted for by this relationship. For fattening herds this relationship appeared curvilinear, with the reduction in the log-odds being more rapid in the 1st year of the program. This non-linear pattern indicates that for the elimination of the risk of ADV-infection from fattening herds of the area, the mass vaccination program should be complemented with additional measures such as test-and-slaughter of infected breeding pigs. A computerized economical model to estimate the effects of ADV-infection at the herd and area level has been developed. The analytical structure consists of a basic epidemiological model linked to an economic estimation framework. The economic model predictions allow priorities to be given to alternative control strategies. Mass vaccination of all pigs in regions with endemically infected herds followed by test-and-removal of seropositive animals is the most cost-effective way to control the spread of ADV within the swine population. Other possible control strategies such as intensive vaccination or complete test-and-removal all had higher overall costs, either because of the less efficient production, or because of the high costs of straight test-and-removal.

Abattoirs↗