The mitochondrial localization of coproporphyrinogen III oxidase.

The location of coproporphyrinogen III oxidase in mitochondria was studied in rat liver by using the digitonin method or hypo-osmotic media for fractionation. The enzyme was found in the intermembrane space with a fraction loosely bound to the inner membrane. This fraction was released by washing the inner-membrane-matrix complex with alkaline solutions or solutions of high ionic strength. The enzyme in both fractions had the same Km (0.16 micrometer) for coproporphyrinogen III. When incubation was performed in a medium that avoided destruction of enzyme membrane binding, a dramatic increase in activity was observed after sonication of whole mitochondria or of the inner-membrane-matrix complex.     

Analysis of VSV mutant with attenuated cytopathogenicity: mutation in viral function, P, for inhibition of protein synthesis.

T1026, a ts mutant of VSV which is much less cytopathogenic than its parent, HR, and which can establish persistent infection under certain conditions, is a double mutant. In addition to its ts mutation in the virion RNA polymerase, T1026 has a second non-ts mutation in a viral function termed "P". This function is responsible for the inhibition of total protein synthesis in infected cells and acts chiefly at the level of translational initiation. In some cell systems, the inhibition of protein synthesis produced by P appears to be selective for cellular protein synthesis, whereas in other cell systems, both cellular and viral protein synthesis are inhibited. T1026 and its ts revertants are phenotypically P- -that is, cells infected with them show total protein synthesis rates equal to or greater than uninfected cells, while synthesizing viral proteins at the same or even greater rates than HR-infected cells. The P- mutation is correlated with failure to increase plaque size after 2-3 days of incubation. Since viral mutants obtained from persistently infected cultures in a variety of systems appear to be double mutants with a ts mutation in the virion RNA polymerase and a small plaque marker, we suggest that T1026 could represent a model for such mutants.     

Pre-clinical studies of the negative pi-meson beam at TRIUMF

Summary The ^– flux from the biomedical channel at TRIUMF increases with increasing channel momentum, while the contaminating electron flux decreases. Since the electrons appear to result from conversion of the high energy-rays produced by ⁰ decay in the production target, the electron contamination can be reduced further by target configurations which minimize gamma conversion.The attenuation of ^– beams by in-flight interactions was found to decrease from an initial value of 1.67 ± 0.02 % per g/cm² at zero depth to 1.48 ± 0.02 % per g/cm² near the stopping peak.The inactivation of cultured CHO cells by an extended-peak ^– dose distribution has been measured using the gel technique. The survival data have been fitted by a model which characterizes the physical quality of the dose profile by means of measured star densities. This model provides a convenient method of analysis for large sets of survival data and may be useful for prediction of the biological effect of new ^– dose distributions.The RBE value for 50% survival measured at the centre of a 7 cm extended peak was found to be approximately 1.4, in reasonable agreement with recent values obtained at LAMPF and SIN.     

Mass balance models of phosphorus in sediments and water

Models are presented in order of progressively more complex spatial resolution in which the effects on the sediment-water interactions are emphasized. For simple models, the diagnostic approach of calculating the net settling and return of total phosphorus is demonstrated with data from Lake Erie. For more complex models, the effects of interbasin transport and vertical mixing are shown to be important in determining the pathways of the sediment-released or sediment-bound phosphorus in the water column.     

Mitochondrial NADH dehydrogenase in cystic fibrosis: enzyme kinetics in cultured fibroblasts.

Differences among cystic fibrosis (CF) genotypes (CF, obligate carriers for CF [HZ], and controls) in mitochondrial calcium pool size, oxygen (O2) consumption, and rotenone inhibition of O2 consumption led to examination of mitochondrial NADH dehydrogenase (NADH: [acceptor] oxidoreductase, E.C. 1.6.99.3). pH optima of mitochondrial NADH dehydrogenase were different in enzyme derived from whole cell homogenates of cultured skin fibroblasts of subjects with CF, HZ, and controls. We describe here apparent binding of substrate to the enzyme (Km [NADH]) in cell fractions. Km (NADH) for CF ranged from 10.9 to 16.1 micro M (no. = 7); for HZ from 20.9 to 26.3 microM (no. = 5). With three exceptions, Km for controls (no. = 12) ranged from 31.8 to 42.8 microM. Km of the three exceptional controls were 21.5, 23.7, and 22.4 microM (the latter two are identical twins). pH optima of enzyme from these three strains were no different from that of known HZ. The correlation between two kinetic parameters of an enzyme and the three CF genotypes suggests an association between the CF gene and mitochondrial NADH dehydrogenase.     

Identification of hemoglobin G-Philadelphia (alpha 68 Asn replaced by Lys) and hemoglobin Matsue-Oki (alpha 75 Asp replaced by Asn) in a black infant

Two alpha-chain variants, Hb G-Philadelphia and Hb Matsue-Oki, were present in members of a relatively large black family from South Carolina. The four Hb G-Philadelphia heterozygotes averaged 35.6% Hb G, suggesting the presence of an alpha-thalassemia-2 condition in cis to the Hb G mutation, which was confirmed by DNA structural analysis. The seven Hb Matsue-Oki heterozygotes averaged 22.2% Hb MO and likely have four active alpha-chain genes. One infant was a compound heterozygote for the two Hb variants which could not be separated from each other. The quantity of Hb G plus Hb MO was 58% by DEAE-cellulose chromatography and 69% by chain analyses. These results and the family data indicate that this child had three active alpha-chain genes, of which one regulated the synthesis of the normal alpha chain, one was mutated to give the alpha G chain, and one to give the alpha MO chain. The amino acid substitutions in Hb G-Philadelphia and Hb Matsue-Oki are located in the tryptic peptide alpha T-9, which is 29 amino acid residues long. Structural analyses of these abnormalities made use of high-pressure liquid chromatography for the separation of both tryptic and thermolytic peptides and of a highly sensitive ultra-micro sequencing procedure. Although the alpha 68 Asn replaced by Lys substitution is readily demonstrable in Hb G-Philadelphia the elucidation of the alpha 75 Asp replaced by Asn replacement in Hb Matsue-Oki was greatly facilitated by the use of these microprocedures.     

Genomic,transcriptomic, and metabolomic analysis of Oldenlandia corymbosa reveals the biosynthesis and mode of action of anti-cancer metabolites

Plants accumulate a vast array of secondary metabolites,which constitute a natural resource for pharmaceuticals.Oldenlandia corymbosa belongs to the Rubiaceae family,and has been used in traditional medicine to treat different diseases,including cancer.However,the active metabolites of the plant,their biosynthetic pathway and mode of action in cancer are unknown.To fill these gaps,we exposed this plant to eight different stress conditions and combined different omics data capturing gene expressi...     

Technical note: CT determination of the mineral density of dry bone specimens using the dipotassium phosphate phantom

Recent studies have demonstrated the potential application of computed tomography (CT) in research into bone density. Clinical studies of bone density using CT commonly employ a dipotassium phosphate phantom to calibrate measurements of mineral density. Designed for in vivo studies, the use of this phantom requires that bones be scanned while immersed in and permeated by fluids or soft tissues similar to water in X-ray attenuation coefficient. However, this condition may not always be met in anthropological applications, which often involve rare and fragile specimens. This study compares mineral density values calculated for a sample of bones scanned—at the same sites—in air and in water. The results indicate that, when scanned in air, the mineral density of trabecular bone is dramatically underestimated, while that of cortical bone is slightly overestimated. We present a linear regression equation to correct this error but recommend that, when possible, researchers calculate their own regressions based on their specific scanning conditions. Am J Phys Anthropol 103:557–560, 1997. © 1997 Wiley-Liss, Inc.     

The amyloid-β1–42-oligomer interacting peptide D-AIP possesses favorable biostability,pharmacokinetics, and brain region distribution

We have previously developed a unique 8-amino acid Aβ42 oligomer-Interacting Peptide (AIP) as a novel anti-amyloid strategy for the treatment of Alzheimer’s disease. Our lead candidate has successfully progressed from test tubes (i.e., in vitro characterization of protease-resistant D-AIP) to transgenic flies (i.e., in vivo rescue of human Aβ42-mediated toxicity via D-AIP-supplemented food). In the present study, we examined D-AIP in terms of its stability in multiple biological matrices (i.e., ex-vivo mouse plasma, whole blood, and liver S9 fractions) using MALDI mass spectrometry, pharmacokinetics using a rapid and sensitive LC-MS method, and blood brain barrier (BBB) penetrance in WT C57LB/6 mice. D-AIP was found to be relatively stable over 3 h at 37 °C in all matrices tested. Finally, label-free MALDI imaging showed that orally administered D-AIP can readily penetrate the intact BBB in both male and female WT mice. Based upon the favorable stability, pharmacokinetics, and BBB penetration outcomes for orally administered D-AIP in WT mice, we then examined the effect of D-AIP on amyloid “seeding” in vitro (i.e., freshly monomerized versus preaggregated Aβ42). Complementary biophysical assays (ThT, TEM, and MALDI-TOF MS) showed that D-AIP can directly interact with synthetic Aβ42 aggregates to disrupt primary and/or secondary seeding events. Taken together, the unique mechanistic and desired therapeutic potential of our lead D-AIP candidate warrants further investigation, that is, testing of D-AIP efficacy on the altered amyloid/tau pathology in transgenic mouse models of Alzheimer’s disease.     

Thyroid regulation of body temperature in anaesthetized chickens

1. Anaesthesia caused marked decreases in the plasma concentrations of triiodothyronine (T3) and thyroxine (T4) and in the body temperature of young fowl. 2. Exogenous T4 or a thyroid hormone secretagogue (somatostatin antiserum), increased endogenous T3 and T4 concentrations and body temperature in conscious birds and prevented the body temperature decline in anaesthetized fowl. 3. These results provide further evidence for a role of T3 and T4 in temperature regulation in birds, particularly during anaesthesia.