A rat-tissue aminotransferase acting on L-tyrosine O-sulphate

1. Rat tissues have been shown to possess an aminotransferase that is active towards l-tyrosine O-sulphate and dependent on 2-oxoglutarate and pyridoxal phosphate. 2. Kidney, liver and pancreas have the greatest activity and the enzyme is localized mainly in the mitochondrial fraction in the liver and kidney cell. 3. The enzyme was shown to be distinct from l-tyrosine-2-oxoglutarate aminotransferase but its true identity was not established. 4. A procedure for the assay of the enzyme in crude tissue preparations was developed.     

GRADED ABRASION—A TREATMENT FOR ACNE

Long term continuous superficial abrasion with abrasive compounds of various degrees of roughness was used over an 11-year period in over 1,500 patients with acne of all types. The following observations were made:• That when a material with a specific abrasive quality is used for a period, desquamation stops despite continued use of the material, and then use of material of the next higher degree of roughness is indicated until the patient''s skin is blackhead-free and minutely flaky.• When long term continuous superficial graded abrasion is used alone or with other treatment, it permits the young patients to outgrow the disease with little or no scarring.• The routine of abrasive washing seems in a large measure to replace the constant fingering of lesions by the patient.• No untoward effects were observed clinically. There was no hyperpigmentation of Negro or Caucasian skins.     

Functional Significance of the Crystal Cells in the Larva of Drosophila melanogaster

Cytoplasmic crystalline inclusions are found in some larval haemocytes of Drosophila melanogaster. Blackening can be experimentally induced in these cells, and previously it was suggested that either the substrate or enzyme for the tyrosine-tyrosinase system leading to melanin production in Drosophila larvae is found in these inclusions in the crystal cells. The present report is an attempt to further localize the enzyme and substrate. Larvae have been fed on food containing α-C¹⁴-tyrosine and autoradiographs of the blood cells taken from these larvae subsequently prepared. The C¹⁴ activity in the crystal cells is restricted to the crystal inclusions in the cells and is significantly higher than that found in the other type of haemocytes, the plasmatocytes. When samples of the blood cells are incubated in DOPA solution, the extra-crystalline cytoplasm becomes blackened while the crystals themselves remain colorless. These observations are consistent with the hypothesis that the substrate is localized in the crystal inclusions whereas enzyme is found in the surrounding cytoplasm. An in vivo structural isolation would serve to separate enzyme and substrate rather than an inhibition by dehydrogenases as postulated by previous authors. In vitro examination with the phase microscope has shown that the crystal cells rupture easily and the crystals dissolve in the haemolymph. Therefore any treatment which tends to disrupt the structural integrity of the cell will allow the enzyme and substrate to come together. Humoral factors preceding metamorphosis might account for the in vivo release of the enzymatic reaction by initially altering the permeability of the cell.     

Effect of various nonionic surfactants on growth of Escherichia coli

Rose, Michael J., Jr. (Veterans Administration Hospital, Washington, D.C.), Stephen A. Aron, and Bernard W. Janicki. Effect of various nonionic surfactants on growth of Escherichia coli. J. Bacteriol. 91:1863-1868. 1966.-Escherichia coli cultivated in media containing 0.5, 1.0, 2.0, or 4.0% concentrations of surface-active polyoxyethylene derivatives of formaldehyde polymers of octyl phenol (Triton WR-1339; Macrocyclon) or of sorbitan mono-fatty acid esters (Tween 20, 40, 60, and 80) exhibited significantly retarded growth only at the highest concentration. To determine the mechanism of bacteriostasis, certain derivatives and compounds related to the surfactants were investigated. Experiments with compounds related to the Triton-type agents demonstrated that incorporation of monomeric substances (Triton X-205, X-305, Igepal CA-730, or Dowfax 9N20) into the medium at a concentration of 4.0% did not inhibit the growth of E. coli. It was concluded that the formaldehyde polymer was essential for growth inhibition by the polyoxyethylene derivatives of octyl phenol. The inhibitory activity of the Tween compounds, in contrast, appeared to result from the unesterified fatty acids which contaminate the commercial preparations. Polyol (60), the sorbitan polyoxyethylene derivative of Tween 60 and the basic structural unit of all the Tween-type compounds, and a Tween 80 preparation which was purified by extraction of the unesterified oleic acid, were not inhibitory. Moreover, the amount of free oleic acid present as a contaminant of Tween 80 was found to be sufficient to cause significant growth inhibition. These results and the observation that E. coli does not appear to hydrolyze the esterified fatty acid of Tween 80 led to the conclusion that growth inhibition obtained with various Tween compounds probaby is a function of their respective fatty acid contaminants.     

Possible involvement of the 90-kDa heat shock protein in the regulation of protein synthesis

The heme-sensitive eukaryotic initiation factor (eIF)-2 alpha kinase regulates translational activity in reticulocytes by phosphorylation of the smallest subunit of eukaryotic peptide initiation factor 2, eIF-2. Highly purified preparations of the kinase contain an abundant 90-kDa polypeptide which appears to modulate the activity of the enzyme. The physical properties and structural characteristics of the reticulocyte 90-kDa peptide are similar to those of the 90-kDa heat shock protein (hsp 90) from HeLa and other mammalian cells. The reticulocyte and HeLa cell proteins are shown to be immunologically cross-reactive. A direct comparison of the two proteins by one-dimensional peptide mapping of large peptides generated by limited proteolysis and by reversed-phase high performance liquid chromatography analysis of tryptic peptides indicates that they represent the same protein species. Like the 90-kDa reticulocyte protein, HeLa cell hsp 90 causes increased eIF-2 alpha phosphorylation by the heme-sensitive kinase and is a potent inhibitor of protein synthesis in the reticulocyte lysate system. A potential mechanism for the latter inhibition is inferred. These results implicate hsp 90 in the regulation of protein synthesis via its interaction with and perhaps regulation of the heme-sensitive kinase and phosphorylation of eIF-2 alpha.     

Predicting variability in catch-per-effort in Atlantic cod, Gadus morhua, trap and gillnet fisheries

The relationships between catch rates and fish abundance, hydrographic conditions and fishing effort, for Atlantic cod caught by trapnets (fixed gear) and gillnets (non-fixed gear) in the northern Gulf of St Lawrence have been quantified. Daily changes in trap catch rates were accounted for by changes in salinity, currents and mean local cod densities in 1985 ( R ²= 0.78), and predicted 1986 trap catch rate changes (by 1985 model) were correlated significantly with those observed ( r = 0.60, P < 0.05). In contrast, the daily changes in 1985 gillnet catch rates were determined by currents, maximum (not mean) local cod densities, and fishing effort (negative) ( R ²= 0.68), while predicted 1986 gillnet catch rates (by 1985 model) were significantly correlated with those observed ( r = 0.35, P < 0.05). Seasonal catchability coefficients of the traps were similar in 1985 and 1986, but for gillnets this index was an order of magnitude higher in 1986 than in 1985.     

The versatile temporoparietal fascial flap: adaptability to a variety of composite defects

The unique properties of the temporoparietal fascial flap (TPFF) offer adaptability in reconstruction of a variety of composite defects. The broad, thin sheet of vascularized tissue may be transferred alone or as a carrier of subjacent bone or overlying skin and scalp. As a pedicled flap, it is ideal for defects of the orbital, malar, mandibular, and mastoid regions. As a free-tissue transfer, the large vessels and lack of bulk find broad utility in reconstruction of the extremities. This flap is our choice for reconstruction of the dorsal hand and non-weight-bearing surfaces of the foot. A viscous gliding surface decreases friction for tendon excursion. The thin contour is aesthetically superior to thicker flaps, allowing unmodified footwear or gloves. The pliable fascia convolutes into surface defects (e.g., bone craters) or drapes over skeletal frameworks (e.g., ear cartilage). The rich capillary network offers nutrition to saucerized bone, cartilage or tendon grafts, and overlying skin grafts. The geometry of the skull lends to fabrication of membranous bone for complex facial puzzles. The donor site is well disguised by hair growth. Twelve cases performed over a 2-year period demonstrate the versatility of this flap. These include complex foot reconstruction, ear and scalp avulsion, shotgun wound of the cheek and orbit, posttraumatic jaw recontouring, chronic osteomyelitis of the hand and foot, and acute resurfacing of dorsal hand with tendon reconstruction.     

Proton transfer in catalysis by fumarase.

Using 3T[14C]malate it was possible to show intermolecular T-transfer to unlabeled fumarate. The rate of dissociation of ET derived from the malate was not rapid, only about as fast as required for KMcat. Because of the slow dissociation of ET derived from T-malate, the awkward complex ET-malate is readily formed. As shown by the effect of added malate on the partition of ET, otherwise captured by fumarate, ET.malate must be functional. Its rate of dissociation to E.M determines the V/Km value of malate. Hydrogen dissociation of the complex ET.F was linearly related to the concentration and basicity of the buffer provided, varying from < 10% to > 60% of the overall rate with alkyl phosphonates. Partition of EH.F to free malate or fumarate occurs in a ratio approximately 2:1 at both low and high buffer. This agrees well with the comparison of the equilibrium exchange rates: malate with [18O]water to malate with [14C]-fumarate [Hansen, J.N., Dinovo, E.C., & Boyer, P.D. (1969) J. Biol. Chem. 244, 6270-6279]. Therefore, the abstracted hydroxyl group is fully exchanged from the enzyme when the bound hydrogen and fumarate return to malate and must be much more accessible to the medium than the abstracted proton. The fact that buffer increases the rate of proton transfer to the medium in the central complex makes it appear that a proton relay connects the active site donor with a remote site that interfaces with the ultimate proton source, water.