Diagnosis of Hunter's syndrome carriers; Radioactive sulphate incorporation into fibroblasts in the presence of fructose 1-phosphate

Summary Mutual correction of co-cultivated fibroblasts from patients with Hunter's and Hurler's syndrome could be inhibited by either fructose 1-phosphate or mannose 6-phosphate. In the presence of fructose 1-phosphate a 50% mixture of fibroblasts from a patient with Hunter's syndrome and a normal homozygous individual showed an increased³⁵S-sulphate incorporation into acid mucopolysaccharides. When fibroblast cultures from one obligate and two possible carriers of Hunter's syndrome were tested for³⁵S-sulphate incorporation, the cultures showed either twice the normal³⁵S-sulphate incorporation into acid mucopolysaccharides in the presence of fructose 1-phosphate or an abnormally high incorporation in the presence as well as in the absence of the sugar phosphate.     

Phenylalanine 4-monooxygenase from bovine and rat liver: Some physical and chemical properties

Phenylalanine 4-monooxygenase was purified from bovine liver using a modification of the procedure developed for the rat liver enzyme (Shiman, R., Gray, D. W., and Pater, A. 1979. J. Biol. Chem. 254:11300–11306). The enzyme preparation appeared essentially homogeneous on polyacrylamide gel electrophoresis under non-denaturing conditions. Electrophoresis in the presence of dodecyl sulfate revealed that about 95% of the protein had a mobility, corresponding to M_r=51,000. The remaining 5% was recovered in two minor bands corresponding to M_r of about 35,000 and 15,000 and is likely to result from limited proteolysis of the native enzyme with dissociation of the fragments on denaturation by detergent. The enzyme comigrated with the rat liver enzyme on polyacrylamide gel electrophoresis in both systems studied. No significant difference was observed between the amino acid composition of the bovine and rat liver enzyme, in the reactivity of their sulfhydryl groups or in their iron content (i.e. 1.5–3.0 iron atoms per peptide chain of M_r=50,000). Both enzymes contained less than 0.01 copper atom per peptide chain. The enzymes were inhibited in a similar manner by the chelator bathophenanthroline disulfonate (selective for iron and copper), but not by bathocuproine disulfonate (specific for copper). The results indicate that the bovine and rat liver enzymes are closely similar and that iron, but not copper, is essential for enzyme activity. High performance size-exclusion liquid chromatography revealed that both native enzymes exist in different oligomeric forms, but further studies are required to understand the physicochemical basis for this phenomenon.Abbreviations Bathophenanthroline 4,7-diphenyl-1, 10-phenanthroline - bathocuproine 2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroline - Hepes N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - dansyl 1-dimethylaminonaphthalene-5-sulfonyl - DMPH₄ 2-amino-4-hydroxy-6,7-dimethyl-5,6,7,8-tetrahydropteridine - M_r relative molecular mass     

Plasma and Tissue Levels of Trimethoprim in The Rainbow Trout,Salmo Gairdneri,After Absorption From Fresh and Salt Water

This is a comparative study of uptake of trimethoprim from 1) fresh water, 2) salt water after 7 days of adaption and 3) salt water without previous adaptation. The rate and extent of absorption were found to vary significantly. The salt water adapted group reached a plasma concentration of approx. 1 µg/ml after 10 h, the unadapted salt water group after 24 to 48 h and the fresh water group did not reach this concentration. The results are discussed in relation to the non-ionic diffusion theory and to the alterations taking place in euryhaline species of fish during adaptation to salt water.     

Fractionation of Soluble Copper- and Zinc-Binding Proteins From Cattle Liver

The distribution of copper and zinc among soluble proteins in liver from normal slaughter cattle was examined after gel filtration of the proteins. Gopper- and zinc-binding proteins were mainly separated into three fractions. Varying amounts of zinc were eluted in a fourth fraction of molecular weight less than 2,000. A clear relationship was noted between the amount of copper bound to the low molecular weight fraction (m.w. ~ 10,000) and the total liver zinc concentration. The high molecular weight protein fraction (m.w. > 65,000) dominated in liver with zinc concentrations below 40 µg/g wet weight and total copper concentrations from 16 to 240 µg/g, while in liver with zinc concentrations above 40 µg/g and copper concentrations ranging from 20 to 107 µg/g, the low molecular weight metallothionein-like fraction dominated.     

Total Thyroxine and Free Thyroxine Index in Plasma of Dairy Cows in Relation To Strength of Heat

Total thyroxine (TT4) and free thyroxine index (FT4I) were measured in peripheral plasma of cows. The samples were collected at the time of insemination from 66 cows showing pronounced signs of the heat and from 56 cows showing weak or silent heat. Neither TT4 or FT4I in plasma differed significantly between the two categories of oestrous cows.     

Abiotic formation of particles from extracellular organic carbon released by phytoplankton

¹⁴C-labeled extracellular organic carbon (EOC) released by the phytoplankton in a Danish Estuary was shown immediately to form particles (>0.2m) when the products were added to a natural water sample. About 14%–20% of the added activity could be recovered as particles. Any bacterial assimilation of the extracellular products was thus masked. The abiotic origin of the particulate EOC was verified, and it was shown that the particle formation was due to some factors present in the estuarine water with a nominal diameter >0.2m. Precaution must be taken to avoid misinterpretations in studies concerning carbon flow from algae to bacteria.     

Rapid down regulation of insulin receptors in adipocytes artifact of the incubation buffer

Rat adipocytes were incubated with 15 nM insulin in different buffers at 37°C. The cells were washed and reincubated at 16°C in the presence of 18 pM A14-[¹²⁵I]monoiodoinsulin to determine the insulin receptor concentration. After incubation for 2 h in Tris buffer the binding decreased to about 30 %, whereas no decrease was found after incubation in Hepes, phosphate or bicarbonate buffers. Binding of tracer insulin reached a constant level by 45 min in Hepes buffer at 37°C, whereas it continued to increase in Tris buffer. Washout of tracer insulin after incubation in Tris buffer at 37°C showed a large, slowly dissociable fraction. It is suggested that the rapid down regulation of insulin receptors $\text{in}\text{vitro}$ is an artifact of the Tris buffer and that the phenomenon is due to a slowly reversible occupancy of a receptor pool with unlabelled insulin.     

Cryopreservation of Sheep Red Blood Cells

The protection of sheep erythrocytes at freezing temperatures was investigated using glycerol, dimethylsulfoxide (DMSO), glucose and four different types of polyvinylpyrrolidone (PVP) as cryoprotective agents. Depending on type (molecular weight) and concentration good protection was obtained with PVP, whereas glycerol, DMSO and glucose were unsatisfactory. Recovery of cells after thawing was most successful when the cells had been frozen at a concentration of 1–2 × 109 cells/ml. No cells tolerated freezing at −20 °G. Best results were obtained when the cells were frozen directly in liquid nitrogen (−196°G).