Energy yield analysis of textured perovskite silicon tandem solar cells and modules.

Perovskite silicon tandem solar cells combine potentially low production costs with the ability to surpass the efficiency limit of silicon single junction solar cells. Optical modeling and optimization are crucial to achieve this ambitious goal in the near future. The optimization should seek to maximize the energy yield based on realistic environmental conditions. This work analyzes the energy yield of perovskite silicon tandem solar cells and modules based on realistic experimental data, with a special focus on the investigation of surface textures at the front and rear side of the solar cell and its implication for reflection as well as parasitic absorption properties. The investigation reveals a 7.3%rel higher energy yield for an encapsulated tandem cell with a textured front side compared with an encapsulated high efficiency single junction solar cell with 24.3% harvesting efficiency for irradiance data of the year 2014 in Freiburg/Germany.

Minor immunophilin binding of tacrolimus and sirolimus metabolites.

OBJECTIVES: We have previously identified three minor immunophilins of molecular weights 37 kDa, 14 kDa, and 5-8 kDa capable of binding tacrolimus and sirolimus. DESIGN AND METHODS: When tested against pure preparations of five sirolimus metabolites, the 14 kDa protein had almost no cross-reactivity, the 37 kDa protein cross-reacted from a high of 23.2% to <10% and the 5-8 kDa protein cross-reacted from <10% to 46.4%. When the 5-8 kDa immunophilin was tested in whole blood samples to assess interference in clinical samples, the demethylated sirolimus metabolites showed about 25% less cross-reactivity while the hydroxylated metabolites reacted about the same. RESULTS: Since MLC data on sirolimus metabolites to date indicates that their pharmacologic potencies are < or =10% of the parent, the 14 kDa immunophilin appears to be the best candidate for a sirolimus radioreceptor assay. The 5-8 kDa immunophilin is newly identified and its cross-reactivity with tacrolimus metabolites had not been assessed. Binding of the 5-8 kDa immunophilin to pure preparations of three tacrolimus metabolites showed virtually no binding of the protein to 13-O-demethyl and 31-O-demethyl tacrolimus and binding to 15-O-demethyl tacrolimus at 121% relative to parent tacrolimus. Cross-reactivity of 15-O-demethyl tacrolimus with the 5-8 kDa protein was then assessed in whole blood samples, and it bound at a level of 163%. MLC data indicates that 31-O-demethyl tacrolimus is equipotent to parent tacrolimus in immunosuppressive activity, while the 13-O-demethyl and 15-O-demethyl have negligible immunosuppressive activity. CONCLUSIONS: Therefore, the 5-8 kDa immunophilin would have limitations in a radioreceptor assay for tacrolimus. In addition, we have evidence that the 5-8 kDa immunophilin is a subunit of a 52 kDa immunophilin previously identified by our group, and the cross-reactivity of the 5-8 kDa immunophilin with these metabolites is similar to that found previously with the 52 kDa, indicating that the two proteins could be related.

Comparison of steady-state trough sirolimus samples by HPLC and a radioreceptor assay.

OBJECTIVES: We have previously identified a minor immunophilin of 52 kDa molecular weight capable of binding tacrolimus and sirolimus. Because immunophilins are capable of binding both parent drug and metabolites and HPLC assays are typically used to assess parent drug in clinical situations, we used this immunophilin in a radioreceptor assay (RRA) to determine if any metabolites not included in the HPLC measurement would bind to the immunophilin and be associated with thrombocytopenia in patients receiving sirolimus. DESIGN AND METHODS: We tested 51 steady-state trough whole blood samples from non-thrombocytopenic patients and 51 steady-state trough samples from thrombocytopenic patients and compared them to HPLC measurements of parent drug in the same samples. We also tested whole blood samples spiked with authentic sirolimus metabolites using RRA to ascertain the effect these metabolites have on the technique. RESULTS: We found minimal cross-reactivity in this assay for sirolimus metabolites (binding ranged from <10% to 26%), and good correlation of the radioreceptor assay with HPLC (linear regression slope 0.92, y-intercept 0.79). There was no statistically significant difference between the RRA and HPLC results in two patient groups-thrombocytopenic and non-thrombocytopenic-using the paired t-test (p<0.005) and Bland-Altman analysis. CONCLUSIONS: These findings indicate that although the RRA could be substituted for HPLC in therapeutic drug monitoring, the 52 kDa immunophilin does not offer an advantage in terms of detecting metabolites associated with thrombocytopenia. However, the RRA offers the advantages of shorter turnaround time, smaller sample volume and potential for automation.

Biochemical characterization of the minor immunophilins.

OBJECTIVE: We present biochemical characterization of the previously described 14 kDa, 37 kDa, and 52 kDa immunophilins and a newly identified 5-8 kDa immunophilin. DESIGN AND METHODS: Proteins were tested for the following enzymatic activities-rotamase, G3PDH, protein kinase C, cAMP dependent protein kinase-and for the ability to inhibit calcineurin phosphatase when complexed with tacrolimus (FK506). RESULTS: The 5-8 kDa protein, like the other minor immunophilins, lacks rotamase activity. Since the 37 kDa possesses G3PDH activity, the 5-8 kDa protein, 14 kDa protein, and 52 kDa protein were all tested and found to lack G3PDH activity. Additional work shows that none of the minor immunophilins possess protein kinase C or cyclic AMP-dependent protein kinase activity and that the 37 kDa and 5-8 kDa and probably the 52 kDa proteins are capable of inhibiting calcineurin phosphatase when bound to tacrolimus.

Pediatric reference ranges for creatine kinase, CKMB, Troponin I, iron, and cortisol.

OBJECTIVES: To determine the pediatric reference ranges for iron, cortisol, CK, CKMB, and troponin I. METHODS: Iron and CK were measured on the Vitros analyzer (Johnson and Johnson) while CKMB, troponin I, and cortisol were measured on the Immuno I (Bayer Corp.). Pediatric reference ranges were determined on hospitalized patients using the Hoffmann approach. RESULTS: Pediatric reference ranges were obtained for iron (AM and PM) and cortisol (AM and PM). Ranges were also obtained for CKMB, troponin I, and total CK. CONCLUSION: This work represents an expansion in our knowledge base on pediatric reference ranges. For iron, the 97.5th percentiles were significantly higher in the PM than in the AM. The diurnal fluctuation in 97.5th percentiles for cortisol was only 10-20%. Pediatric reference ranges for CKMB were not previously available and are important especially in the first year of life. The elevated Troponin I is found in the first year of life also represents new data.

The effect of gestational age, birth weight, and disease on troponin I and creatine kinase MB in the first year of life.

OBJECTIVES: To determine the effect of gestational age and birth weight (BW) on troponin I (TnI) and creatine kinase MB fraction (CKMB) levels during the first year of life. METHODS: Troponin I and CKMB levels were determined in infants less than 1 year of age using the Immuno I (Bayer Corp.). RESULTS: Troponin I fractions were greatest in the preterm infant; the levels decreased significantly with increasing gestational age and BW, (p = 0.008 and p = 0.005, respectively). The CKMB levels did not exhibit a significant difference between the preterm and term infant groups when assessed for the effects of gestational age or BW (p = 0.12 vs. p = 0.35). Neither TnI nor CKMB levels were significantly different between preterm survivors and nonsurvivors (p = 0.31; p = 0.34, respectively). TnI levels were elevated in critically ill patients without documented myocardial infarction, and without a comparable rise in CKMB. CONCLUSION: The higher TnI levels during the first 3 months of life may indicate programmed cell death, or apoptosis. This may be especially true in the preterm infant in which the greatest values were documented.

Cyclosporine metabolite cross-reactivity in different cyclosporine assays.

OBJECTIVES: There is a controversy regarding the role of cyclosporine (CsA) metabolites in both immunosuppression and toxicity, and measurement of the parent drug is commonly recommended. High performance liquid chromatography (HPLC) is the method commonly used for specific measurement of the parent drug, but is very time consuming. Antibody techniques are available but vary in specificity. Mixed lymphocyte culture assay (MLC) is a functional bioassay for the measurement of CsA which measures both parent drug and active metabolites. Because it is time consuming and labor intensive, it is not practical to use the MLC to monitor patient's CsA levels. The objective of this study is to evaluate the degree of cross-reactivity or interference among two different CsA immunoassays [(Immunoassay: CYCLO-Trac-RIA, Monoclonal-TDX; and two radioreceptor assays (RRA) (52 kDa immunophilin and cyclophilin)] with seven cyclosporine metabolites (AM19, AM1c9, AM4n9, AM1, AM9, AM1c, AM4n). The results are compared with a previously published MLC assay for the same metabolites. METHODS: 500 ng/mL of each of the CsA metabolites was assayed in spiked blood samples with both RRA using 52 kDa immunophilin and commercial cyclophilin and two commonly used commercial immunoassay procedures. The results were compared to those obtained with the previously published MLC assay. RESULTS AND CONCLUSION: The CYCLO-Trac-radioimmunoassay showed minimal cross-reactivity with all of the seven CsA metabolites tested and is more specific to parent CsA than the current Abbott monoclonal procedure for the measurement of CsA. However the cross-reactivity of the seven metabolites using the Abbott monoclonal assay matched closely with their pharmacological potency as measured in the MLC assay. The RRAs showed greater cross-reactivity for most of the CsA metabolites tested than that found in the immunoassay procedures.

Tacrolimus metabolite cross-reactivity in different tacrolimus assays.

OBJECTIVES: Tacrolimus (FK506) is an immunosuppressive drug with great clinical promise. There is a controversy regarding the role of tacrolimus metabolites in immunosuppression and toxicity, and immunoassays and immunophilin binding assays have not been adequately tested for metabolite cross-reactivity. Methods are limited to HPLC and HPLC-MS for quantifying the parent drug. Mixed lymphocyte culture assay (MLC) is the preferred functional bioassay for the measurement of parent drug and active metabolites but it is not practical for routine laboratory use. Due to differences in assay methods and reagent specificity, the concentration of tacrolimus in a given specimen may vary among different assay kit manufacturers. The objective of this study was to evaluate the degree of cross-reactivity or interference of the three first-generation tacrolimus metabolites [13-O-demethyl (M-I), 31-O-demethyl (M-II) and 15-O-demethyl (M-III)] among two different tacrolimus immunoassays (Immunoassay: PRO-Trac II FK506, Abbott IMx tacrolimus-II); and the radioreceptor assays (RRA) using minor immunophilins (14, 37, and 52 kDa immunophilins) and tacrolimus binding protein (FKBP12). METHODS: First-generation tacrolimus metabolites (M-I, M-II, and M-III) spiked in drug-free whole blood were assayed with RRA using three minor immunophilins (14, 37, and 52 kDa) and two commercial immunoassay procedures (Incstar PRO-Trac II tacrolimus, Abbott IMx tacrolimus II). The results were compared to previously published FKBP-12 RRA data and their immunosuppressive potency. RESULTS AND CONCLUSION: The first generation tacrolimus metabolites (M-I, M-II, and M-III) were tested using concentrations of 10 and 20 ng/mL. The significance of the metabolite interference (% of the total interference) was calculated based on the relative concentration of each metabolite present at steady-state trough concentrations in renal transplant recipients (22). Metabolite I, which has no functional immunosuppressive activity showed minimal interference compared to M-II and M-III in all assays except the 14 kDa RRA. The Incstar PRO-Trac II tacrolimus assay showed the least M-I interference. Metabolite-II, which has a pharmacologic potency similar to the parent drug, showed a significant interference in the immunoassays and significant interference in radioreceptor assays. Metabolite III, which is pharmacologically inactive, produces 3-10% interference in the different assays if its presence in the blood is 6% of the parent drug. The total interference from these three metabolites was greater in the immunoassays than in the receptor assays. Receptor assays for tacrolimus provide results closer to the target value than do immunoassays.

Radioreceptor assay for sirolimus in patients with decreased platelet counts.

OBJECTIVE: Sirolimus (RAPA) is a new immunosuppressive drug currently in Phase III clinical trials in combination with cyclosporine A (CsA). The toxicity profiles for CsA and RAPA are only partially overlapping, with RAPA toxicity consisting primarily of hyperlipidemia and myelodepression but without the nephrotoxicity, neurotoxicity, and hepatotoxicity, which are seen with CsA. Patients in the clinical trial are being monitored using HPLC or LC/MS/MS assays; there is no immunoassay for RAPA reported to date. We have previously reported a radioreceptor assay (RRA) for RAPA, which has an excellent correlation with the HPLC assay (r = 0.997). The RRA has several advantages including excellent precision, sensitivity, rapid turnaround time, and a one-step extraction procedure. We report the evaluation of blood samples from patients who were exhibiting RAPA toxicity and comparison of the RRA results with the HPLC results. METHODS: EDTA whole blood specimens (n = 42) were obtained from six renal transplant recipients taking RAPA and CsA and exhibiting decreased platelet counts. Thirty-two samples from patients without decreased platelet counts were also received. The samples were analyzed with the RRA and the results were compared to those obtained with the HPLC assay. RESULTS: By HPLC, the results ranged from 3.2-72.6 micrograms/L RAPA with 43% of the results > or = 30 micrograms/L. With the RRA, the range was 7.7-83.0 micrograms/L RAPA equivalents, with 60% of the results > or = 30 micrograms/L. The RRA results are distinctly higher than the HPLC results all along the range. The correlation between the two assays was 0.861, with a slope of 0.966 and a Y-intercept of 11.1. CONCLUSION: Since the RRA is consistently higher than HPLC concentration in patients with decreased platelet counts, but correlates well in patients with no signs of toxicity, the RRA may be useful for monitoring patients for toxicity, by giving a better indication of increasing degree of immunosuppression than the HPLC assay.

Evaluation of i-STAT portable clinical analyzer in a neonatal and pediatric intensive care unit.

OBJECTIVE: To evaluate the Point-of-Care (POC) i-STAT system for measuring blood gases (pH, pCO2, pO2) and whole blood electrolytes (sodium, Na+, potassium, K+ and ionized calcium, iCa2+) in the neonatal and pediatric intensive care units. DESIGN AND METHODS: The i-STAT system was evaluated for imprecision, necessity of running quality control and accuracy. Comparison of patients' samples analyzed by the i-STAT system and the Ciba Coming 288 blood gas analyzer were performed. The reliability of the i-STAT system when performed by non-laboratory personnel was assessed. RESULTS: The system was evaluated for imprecision and linearity using three concentrations of aqueous standards. Except for pO2, the %CVs were < 3.0 for all the analytes (pH, pCO2, Na+, K+ and iCa2+) at all the three concentrations. Using whole blood studies the precision data gave %CVs that were < 3.5 for all the analytes. Linearity studies showed good linearity over the five different concentrations tested. Comparison of the i-STAT and the Ciba Coming 288 blood gas analyzer was assessed by split sample measurement. Patients' results from the i-STAT correlated well with the Ciba Coming 288 blood gas analyzer (r = 0.99 for pH, pCO2 and pO2 and 0.95 to 0.99 for Na+ and K+) with the exception of iCa2+ (r = 0.73). There was no significant difference in the results when operated by PICU/NICU nurses or laboratory personnel. A further study was made to assess whether routine quality control (QC) samples are necessary when using the i-STAT system. The regression analysis (slope and correlation coefficient) of the results from instruments run with and without QC samples gave results close to 1, indicating that there is no need to run additional quality control (QC). CONCLUSION: The POC testing analyzer i-STAT is a reliable alternative to the traditional blood gas analyzers and provides marginal improvement in turnaround time when compared with the service received from the PICU/NICU laboratory. Costs need to be carefully controlled.

Identification of a 37 kDa tacrolimus, sirolimus and cyclosporine binding immunophilin possessing glyceraldehyde 3-phosphate dehydrogenase activity isolated from the Jurkat T cell line.

OBJECTIVE: The isolation and partial characterization of a 37 kDa minor immunophilin from the Jurkat cell line which binds to cyclosporine (CsA), Tacrolimus (FK506) and Sirolimus (RAPA). DESIGN AND METHODS: Using standard protein purification steps including isoelectric focusing and cation exchange chromatography, we have isolated and purified to homogeneity a minor immunophilin from the Jurkat cell line which has a molecular weight of 37 kDa. Binding properties for immunosuppressive drugs CsA, FK506 and RAPA were assessed by Scatchard and displacement analysis. The amino acid analysis and the protein sequences were also studied. RESULTS: The immunophilin was purified to homogeneity and the molecular weight corresponds to 37 kDa. Saturation experiments using 3Hdihydro FK506 gave a Kd of 4.5 nM and the Bmax of 117 nmol/mg protein. Displacement studies using 3Hdihydro FK506 and RAPA gave a Kd of 0.8 nM. For CsA binding, the protein showed somewhat less avid binding. The amino acid composition was in close agreement with the amino acid composition of uracil DNA glycosylase which corresponds to part of the monomer of glyceraldehyde 3 phosphate dehydrogenase (G3PD). Protein digestion gave at least 3 peptides. The primary sequence of the first of these matched 7 of 8 residues of human liver nuclear uracil DNA glycosylase. The 37 kDa immunophilin was found to have G3PD activity not inhibited by FK506. CONCLUSIONS: The amino acid analysis, protein sequences, binding properties and G3PD activity indicate that this 37 kDa immunophilin is different from any other known immunophilins.

Radioreceptor assay for sirolimus.

OBJECTIVES: To develop a radioreceptor assay (RRA) for sirolimus (rapamycin, RAPA). METHODS: A direct methanol extraction was used to prepare 45 patient samples for the RRA. Results were compared to the results obtained previously using high-performance liquid chromatography (HPLC). Between-run precision, recovery, and drug interference studies were also performed. RESULTS: The RRA is sensitive to 1.0 microgram/L RAPA equivalents in whole blood. Comparison with HPLC yielded a correlation coefficient for 45 patient samples of 0.977. Between-run precision at 2.5, 7.5, 12.5, and 20 micrograms/L showed coefficients of variation (CVs) of 12.9, 9.2, 8.5, and 5.9%, respectively. Recoveries from the extraction procedure were 93% at 7.5 micrograms/L and 103% at 12.5 micrograms/L. Drug interference studies showed no interference in the RRA by cyclosporine (CsA), dexamethasone, prednisone, or methotrexate. CONCLUSION: We have demonstrated that the RRA for RAPA correlates well with HPLC, and has excellent precision and recovery. The procedure is far less time-consuming and complex than HPLC and has potential for automation.

Comparison of binding characteristics of four rapamycin metabolites to the 14 and 52 kDa immunophilins with their pharmacologic activity measured by the mixed-lymphocyte culture assay.

OBJECTIVES: To compare the binding characteristics of four rapamycin (RAPA) metabolites to the 14 and 52 kDa minor immunophilins with their pharmacologic activity, as measured by the mixed-lymphocyte culture (MLC) assay. METHODS: Four RAPA metabolites were isolated by HPLC from the urine of renal transplant patients. Each metabolite was evaluated at 40 micrograms/L for its pharmacologic activity using the MLC assay. The results of the MLC assay were compared to those obtained using the radioreceptor assay (RRA), which measured the binding characteristics of equal concentrations of the metabolites to the 14 and 52 kDa minor immunophilins. RESULTS: Each of the four RAPA metabolites showed low immunosuppressive activity by MLC. RM2 showed the highest activity, with 9% of parent RAPA activity. RM1, 3, and 4 showed 2%, 8%, and 4% activity, respectively. Only RM1 was found to bind significantly to either minor immunophilin, with 21% of parent binding to the 14 kDa protein and 25% of parent binding to the 52 kDa protein. RM2, 3, and 4 bound to both proteins with < or = 2% of parent binding. CONCLUSION: We have demonstrated that the RRA for these four RAPA metabolites shows little cross-reactivity. There is no commercially available immunoassay for RAPA at present. The RRA, therefore, provides an excellent way to rapidly assess efficacy/toxicity of RAPA in patients receiving the drug.

Evaluation of the Technicon Immuno I random access immunoassay analyzer and calculation of pediatric reference ranges for endocrine tests, T-uptake, and ferritin.

OBJECTIVES: Evaluation of the precision, accuracy, and user-friendliness of the Technician Immuno I. Calculation of pediatric reference ranges for ferritin and endocrine tests run on Immuno I. METHODS: Precision and accuracy were measured using controls and method comparison studies. Pediatric reference ranges were calculated by comparing the Immuno I results for 100 patients with those of the Abbott IMx and TDx. The regression equation obtained was then used to convert the IMx and TDx reference ranges to reference ranges for the Immuno I. RESULTS: The Immuno I provided both accurate and precise measurement of drugs and endocrine hormones. Pediatric reference ranges were obtained for ferritin and all endocrine tests. CONCLUSION: The Immuno I is user-friendly and provides reliable measurement of both the drugs tested and endocrine tests on a micro-sample. Reagent and curve stability are excellent.

Identification of a 14 kDa FK-506/rapamycin binding immunophilin from calf thymus.

Specific binding proteins (immunophilins, 12-17 kDa) have been described in the cytosol for the immunosuppressant drugs cyclosporine, FK-506, and rapamycin. We describe the identification of a low abundant minor immunophilin (14 kDa) from calf thymus. Saturation experiments using dihydro[3H]-FK-506 gave a Kd of 2 nM and the Bmax of 72 nmol/mg protein. At saturation, 71.3 nmol of FK-506 is bound per mg of the 14 kDa protein (71 nmol) giving a drug/protein ratio of 1.0. Competition experiments using 3H-dihydro FK-506 and rapamycin showed displacement of rapamycin, with Kd in the range of 40 nM. The 14 kDa immunophilin does not have peptidyl-prolyl cis-trans isomerase activity with any of the four substrates investigated. Initial amino acid analysis and protein sequencing data indicate that the immunophilin is different from both the 12 kDa FK-506 binding protein and any other known protein.

Immunophilin receptors for immunosuppressive drugs.

The major immunophilins that bind cyclosporine (cyclophilin) and FK-506/rapamycin (FK-BP 12) have been well characterized. They possess rotamase activity, which is inhibited by the immunosuppressant that binds to them. The immunosuppressive action does not appear to be coupled to rotamase activity. The literature is reviewed on some possible mechanisms of immunosuppression. Minor immunophilins of 14, 36, and 52 kDa have also been isolated and partially characterized. Receptor assays employing immunophilins have been developed.

Temporal changes in superoxide dismutase, glutathione peroxidase, and catalase levels in primary and peri-ischemic tissue. Monosialoganglioside (GM1) treatment effects.

Time-dependent changes in levels of the antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GSHPOD), and catalase (CAT) after cortical focal ischemia in rat indicate that: (1) primary and peri-ischemic tissues differ in both rate and the magnitude of oxyradical-induced ischemic injury, and (2) ischemic tissue remains vulnerable to oxyradical damage as long as 72 h after ischemia since the antioxidant enzyme levels remain at or below basal levels. After 72 h, the increased levels of these enzymes are sufficient to protect tissue against oxyradical damage. GM1 ganglioside (10 mg/kg, im) further increased the already elevated levels of the enzymes after ischemia, thereby indicating the GM1 treatment increases the capacity of ischemic tissue to protect against oxyradical injury.

Novel regulation of 5-HT1C receptors: down-regulation induced both by 5-HT1C/2 receptor agonists and antagonists.

The 5-hydroxytryptamine1C (5-HT1C) receptor shares many features with the 5-HT2 receptor. To determine if the regulation of the sites is also similar we studied the effects of chronic treatment with drugs active at 5-HT1C/2 receptors on [3H]mesulergine-labelled 5-HT1C binding sites in spinal cord. The 5-HT receptor agonists 1-(3-chlorophenyl)piperazine (m-CPP) (-38%), 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) (-35%), quipazine (-27%) and m-trifluoromethylphenylpiperazine (TFMPP) (-27%) significantly down-regulated spinal 5-HT1C sites with chronic injection compared to vehicle treatment. The 5-HT receptor antagonists methiothepin (-71%), mianserin (-24%), methysergide (-21%), and cyproheptadine (-27%) also induced down-regulation, and ritanserin and metergoline further reduced [3H]mesulergine specific binding to undetectable levels. There were no significant changes in Kd to implicate presence of residual drug except for mianserin, methiothepin, and TFMPP. Pindolol and spiperone had no significant effects. In acute dose-response studies, injection of a single dose of DOI did not result in a significant change in any receptor parameters. The capacity of a drug to lower Bmax correlated significantly with its pKd (r = 0.84, P < 0.0007). This drug regulation pattern for 5-HT1C sites of down-regulation by both 5-HT1C/2 receptor agonists and antagonists is similar to that for 5-HT2 receptors and is consistent with the classification of 5-HT1C and 5-HT2 receptors in the same superfamily.