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PubMed1980

Comparison of four different algorithms for the calculation of radioimmunoassay standard curves.

Standard curves from 150 determinations of 10 different hormone radioimmunoassays have been evaluated using the following four procedures: logit transformation as performed by Rodbard, Healy's 4-component-logit, spline approximation and a linear interpolation program. The results, calculated by computer, have been compared with manual analysis as the refernce method. The influece of various correction factors has been studied by artificial insertion of outliers. Approximately two thirds of all investigated curves could be calculated with almost equal success using all 4 methods. In calculating the remaining third of the standard curves, each method showed characteristic errors which depended upon the reliability of the assay data and the kind of outliers. The results suggest that the smoothing by spine function is the most flexible method in approximating a radioimmunoassay standard curve. In comparison with the other methods it is less influenced by random errors and fits the characteristic and symmetry of the ideal curve most exactly. The 4-component logit which has been extended by data screening is an improvement of the original logit transformation. Certain reservations exist, however, in elimination of outliers because of the dispersion of the data points, and also because of the arbitrarily set thresholds.

Mathematics↗
PubMed1992

Characterization of opioid binding sites in rat spinal cord.

Binding sites were characterized in rat whole spinal cord crude membrane preparations using selective labelling techniques with multiple methods of mathematical analysis of experimental curves. Mathematical analysis of single [3H]-[D-Ala2,MePhe4,Gly-ol5] enkephalin (DAGO) saturation curves suggested binding of the [3H]-ligand at one site, while displacement curves of low concentrations of [3H]-DAGO with selective mu-ligands indicated the presence of high- and low-affinity sites. All the [3H]-DAGO curves processed simultaneously by LIGAND analysis showed the presence of high (27%) and low (73%) affinity components, with a total Bmax of 3.19 pmol/g tissue. Eighty percent of [3H]-[D-Ala2,D-Leu5] enkephalin (DADLE) binding was displaced by DAGO with high affinity, indicating that a high percentage of [3H]-DADLE binding was at mu-sites. Saturation curves of [3H]-DADLE after inhibition of mu-sites by unlabelled DAGO (delta-sites) were monophasic with non-linear fitting analysis and the Bmax was 0.90 pmol/g tissue. Most mathematical analysis of single saturation curves of [3H]-(-)-bremazocine indicated binding at more than one site. DAGO, DADLE, U-69,593 and PD 117302 displaced 0.15 nM of [3H]-(-)-bremazocine biphasically: the percentages of displacement calculated with the non-linear fitting program were respectively 50 (mu-sites), 64 ((mu + delta)-sites), 18 and 25 (kappa-sites). Haloperidol displaced [3H]-(-)-bremazocine only at microM concentrations. suggesting no binding at sigma-sites. In the presence of 225 nM of DAGO, DADLE displaced only 21% of [3H]-(-)-bremazocine 0.15 nM binding (delta-sites). Most mathematical analysis of saturation curves of [3H]-(-)-bremazocine, after inhibition of binding at mu- and delta-sites by DAGO and DADLE, still indicated binding at more than one site and the selective kappa-ligands U-69,593 and PD 117302 displaced [3H]-(-)-bremazocine in these experimental conditions. LIGAND analysis of saturation and inhibition curves of [3H]-(-)-bremazocine by U-69,593 and PD 117302 showed the presence of high (43%) and low (57%) affinity components, with a total Bmax of 2,73 pmol/g tissue. Thus in rat spinal cord there are at least two mu-sites bound by [3H]-DAGO which amount together to approximately 47% of total opioid sites, delta-sites bound by [3H]-DADLE amounting to approximately 13%, kappa-sites and other unknown sites (possibly a kappa-subtype) bound by [3H]-(-)-bremazocine, which together are approximately 40% of total opioid sites.

Animals↗
PubMed1984

Relationships between linear type scores, objective type measures, and indicators of mastitis.

Objectives were to examine the usefulness of objective measures of conformation and linear scores for type for predicting indicators of mastitis. Approximately 300 cows in five herds were scored in the experimental linear classification program of the Holstein-Friesian Association of America, measured objectively for numerous components of conformation, and evaluated for four indicators of mastitis. Indicators of mastitis were average natural logarithm of somatic cell counts during the lactation, percent of samples (taken approximately every 3 mo) infected during a lactation, percent of samples infected with Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, Klebsiella, and percent of samples with signs of mastitic milk. Relationships between conformation and mastitis often were inconsistent because of moderate or low correlations between indicators of mastitis. Indicators of mastitis were predicted from results of multiple regression analyses with subjective scores and objective measures of type as independent variables. Largest differences of predicted indicators of mastitis from variation in any single type trait were sufficient to be important economically, but average differences were much smaller. Selection to reduce frequencies of cows with deep udders, especially low rear udders, widely placed teats, rear teats too far back, and teats that are short and wide, may augment, modestly, efforts to reduce incidence of mastitis through improved sanitation, antibiotic treatment, and proper milking procedures.

Animals↗
PubMed2001

Technical efficiency of public clinics in Kwazulu-Natal Province of South Africa.

BACKGROUND: In sub-Saharan Africa (SSA) much of the attention of policy makers, health care managers, health systems researchers and donors is focussed almost solely on mobilising additional resources and not on efficiency in their use. OBJECTIVE(S): To investigate the technical inefficiencies among 155 primary health care clinics in Kwazulu-Natal Province of South Africa; and to draw policy implications. DESIGN: Cross-sectional provincial health clinic survey. SELLING: Kwazulu-Natal Provincial Department of Health Clinics survey, 1996. SUBJECTS: The analysis is based on 155 public clinics. INTERVENTIONS: Non-intervention Data Envelopment Analysis (DEA) study. MAIN OUTCOME MEASURES: Technical and scale efficiency scores. RESULTS: Forty seven (30%) were found to be technically efficient. Among the 108 (70%) technically inefficient facilities, 16% had an efficiency score of 50% or less. The presence of inefficiencies indicates that a clinic has excess inputs or insufficient outputs compared to those clinics on the efficiency frontier. To achieve technical efficiency, Kwazulu-Natal clinics would, in total have to decrease inputs by 417 nurses and 457 general staff. Alternatively, outputs would have to be increased by 115,534 antenatal visits, 1,010 births (deliveries), 179,075 child care visits, 5,702 dental visits, 121,658 family planning visits, 36,032 psychiatric visits, 56,068 sexually transmitted disease visits and 34,270 tuberculosis visits. CONCLUSION: There is need for more detailed studies in a number of the relativdy efficient clinics to determine why they are efficient with a view of documenting attributes of 'best practise' that other clinics can emulate. The potential benefit of replicating this kind of study in other provinces, and indeed, other SSA countries cannot be overemphasised.

Community Health Centers↗
PubMed2002

A management information system to study space diets.

A management information system (MIS), including a database management system (DBMS) and a decision support system (DSS), was developed to dynamically analyze the variable nutritional content of foods grown and prepared in an Advanced Life Support System (ALSS) such as required for long-duration space missions. The DBMS was designed around the known nutritional content of a list of candidate crops and their prepared foods. The DSS was designed to determine the composition of the daily crew diet based on crop and nutritional information stored in the DBMS. Each of the selected food items was assumed to be harvested from a yet-to-be designed ALSS biomass production subsystem and further prepared in accompanying food preparation subsystems. The developed DBMS allows for the analysis of the nutrient composition of a sample 20-day diet for future Advanced Life Support missions and is able to determine the required quantities of food needed to satisfy the crew's daily consumption. In addition, based on published crop growth rates, the DBMS was able to calculate the required size of the biomass production area needed to satisfy the daily food requirements for the crew. Results from this study can be used to help design future ALSS for which the integration of various subsystems (e.g., biomass production, food preparation and consumption, and waste processing) is paramount for the success of the mission.

Biomass↗
PubMed2000

[Determination of chiral purity of synthetic amino acids by high performance liquid chromatography].

A series of synthetic beta-heterocyclic and beta-naphthyl alanine and aromatic substituted phenylalanine were separated by reversed-phase HPLC as diastereomeric derivatives obtained after derivatization with (1-fluoro-2,4-dinitrophenyl)-5-L-valinamide (FDNP-Val-NH2). The separation was performed with gradient elution. The mobile phase A was acetonitrile containing 0.1% trifluoroacetic acid and mobile phase B was 0.1% trifluoroacetic acid. According to the hydrophobicity of the side chain of the amino acids, 6 different linear gradient programs were selected and all gradients completed in 20 minutes. Good resolution was obtained for neutral amino acids. All L-L diastereomer of neutral amino acids (the first letter refers to the configuration of amino acid) were eluted faster than the D-L diastereomer with retention times less than 16 minutes. In the same gradient eluting system, the hydrophobic parameter (pi value) and the position of the substituent in benzene ring of phenylalanine also influence the retention time of diastereomers. Usually the retention time of the phenylalanine with a large pi value was longer than that with a small one. Among the three phenylalanines containing the same substituent, compounds with the substituent in 2-postion gave the shortest retention time. In the case of basic amino acids, the D-L diastereomers eluted prior to the L-L diastereomers and showed rather poor resolution. The chiral purity (ee) of the optical active amino acids (synthetic DL-amino acids after resolution by different enzymes) were calculated with the equation as follows: ee = [[A(L- or D-) - A(D- or L-)]/[A(L-) + A(D-)]] x 100% (L- or D-), A: peak area; L-, D-: amino acid diastereomer.

Amino Acids↗
PubMed1992

Ownership and organizational performance. A comparison of technical efficiency across hospital types.

Using a national data base of urban hospitals, the effect of ownership (government, nonprofit, and for-profit) on the technical efficiency of hospitals was examined. Efficiency scores were computed using a method called data envelopment analysis. Controlling for environmental and hospital characteristics, for-profit hospitals were found somewhat less frequently and government hospitals consistently more frequently in the efficient category. When examining highly inefficient hospitals as a percentage of those receiving inefficient scores, for-profit hospitals appeared to be highly inefficient relative to the other ownership forms. Government and nonprofit hospitals were somewhat indistinguishable from one another regarding their percentages of highly inefficient scores. For-profit hospitals also tended to use supply and capital asset (hospital size) inputs less efficiently, and service and labor inputs more efficiently than hospitals in the other ownership categories.

Efficiency↗