A tandemly reiterated DNA sequence in the long repeat region of herpes simplex virus type 1 found in close proximity to immediate-early mRNA 1.

The 3' end of immediate-early mRNA 1 was mapped precisely within the IRL/TRL genome regions, and the DNA sequences around the 3' end were determined. An AATAAA polyadenylation signal was present 17 base pairs upstream of the 3' end, and eight tandemly repeated copies of a 16-base-pair sequence (GGGGGTGCGTGGGAGT) plus one further closely related copy were located 20 base pairs downstream. Other tandem reiterations present in the herpes simplex virus genome are described and their properties are considered.     

Changes in quantity, composition, and surface activity of alveolar surfactant at birth

We hypothesized that when the lung makes the transition from the fluid- to the air-filled state at birth, there are changes in physical and functional properties of the alveolar surfactant. To test this hypothesis, newborn rabbits were killed at different times in the first 24 h of life, their lungs lavaged with ice-cold saline, and the lavage fluid subfractionated by differential centrifugation. The phospholipid and protein content and composition and the kinetics of surface tension lowering of the subfractions were examined. We found that with the onset of breathing, shifts occur in the distribution of surfactant subfractions as a surfactant apoprotein-free phospholipid fraction is generated. The ratio of rapidly sedimentable apoprotein-rich to slowly sedimentable, apoprotein-free fractions decreases from 31 at birth to 4 at 24 h of life. Concurrently, rates of surface tension lowering by the subfractions increase with time. The results suggest that the adult pattern of pool sizes and surface activity of alveolar surfactant is not present at birth but evolves slowly over the 1st day of life.     

A high recovery method for concentrating microgram quantities of protein from large volumes of solution

A method is presented for the recovery of 40-80% of the protein from a 1 microgram/ml solution. The final protein pellet is free of detergent and other ionic compounds and is thus compatible with any denaturing solution. The primary structure of the protein is unaffected by the procedure, making the final pellet an ideal sample for any analytical procedure to determine protein structure.     

Lengthening versus shortening dark periods and blossoming in sugar cane as affected by temperature

Sugar cane, an intermediate day plant, clearly received a stronger stimulus to flower during lengthening nights than during shortening nights. Flowering was vigorous under warm, lengthening nights (21°) but less so under cool, lengthening nights (16-17°). Warm or cool shortening nights either failed to induce flowering altogether or reduced it substantially. Under the warmer nights the inductive dark period was 10 hours 57 minutes to 11 hours 26 minutes whether the nights were lengthening or shortening. Under cooler conditions, it was longer by from 20 minutes to nearly 2 hours.     

Immunoquantification and enzyme kinetics of alpha-L-iduronidase in cultured fibroblasts from normal controls and mucopolysaccharidosis type I patients.

alpha-L-Iduronidase activity is deficient in mucopolysaccharidosis type I (MPS I; Hurler syndrome, Scheie syndrome) patients and results in the disruption of the sequential degradation of the glycosaminoglycans dermatan sulfate and heparan sulfate. A monoclonal antibody-based immunoquantification assay has been developed for alpha-L-iduronidase, which enables the detection of at least 16 pg alpha-L-iduronidase protein. Cultured human skin fibroblasts from 12 normal controls contained 17-54 ng alpha-L-iduronidase protein/mg extracted cell protein. Fibroblasts from 23 MPS I patients were assayed for alpha-L-iduronidase protein content. Fibroblast extracts from one MPS I patient contained at least six times the level of alpha-L-iduronidase protein for normal controls--but contained no associated enzyme activity--and is proposed to represent a mutation affecting the active site of the enzyme. Fibroblast extracts from 11 MPS I patients contained 0.05-2.03 ng alpha-L-iduronidase protein/mg extracted cell protein, whereas immunodetectable protein could not be detected in the other 11 patients. Four fibroblast extracts with no immunodetectable alpha-L-iduronidase protein had residual alpha-L-iduronidase activity, suggesting that the mutant alpha-L-iduronidase in cultured cells from these MPS I patients has been modified to mask or remove the epitopes detected by two monoclonal antibodies used in the quantification assay. Both the absence of immunoreactivity in a mild MPS I patient and high protein level in a severe MPS I patient present limitations to the use of immunoquantification analysis as a sole measure of patient phenotype. Enzyme kinetic analysis of alpha-L-iduronidase from MPS I fibroblasts revealed a number of patients with either abnormal substrate binding or catalytic activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Human liver iduronate-2-sulphatase. Purification, characterization and catalytic properties.

Human iduronate-2-sulphatase (EC 3.1.6.13), which is involved in the lysosomal degradation of the glycosaminoglycans heparan sulphate and dermatan sulphate, was purified more than 500,000-fold in 5% yield from liver with a six-step column procedure, which consisted of a concanavalin A-Sepharose-Blue A-agarose coupled step, chromatofocusing, gel filtration on TSK HW 50S-Fractogel, hydrophobic separation on phenyl-Sepharose CL-4B and size separation on TSK G3000SW Ultrapac. Two major forms were identified. Form A and form B, with pI values of 4.5 and less than 4.0 respectively, separated at the chromatofocusing step in approximately equal amounts of recovered enzyme activity. By gel-filtration methods form A had a native molecular mass in the range 42-65 kDa. When analysed by SDS/PAGE, dithioerythritol-reduced and non-reduced form A and form B consistently contained polypeptides of molecular masses 42 kDa and 14 kDa. Iduronate-2-sulphatase was purified from human kidney, placenta and lung, and form A was shown to have similar native molecular mass and subunit components to those observed for liver enzyme. Both forms of liver iduronate-2-sulphatase were active towards a variety of substrates derived from heparin and dermatan sulphate. Kinetic parameters (Km and Kcat) of form A were determined with a variety of substrates matching structural aspects of the physiological substrates in vivo, namely heparan sulphate, heparin and dermatan sulphate. Substrate with 6-sulphate esters on the aglycone residue adjacent to the iduronic acid 2-sulphate residue being attack were hydrolysed with catalytic efficiencies up to 200 times above that observed for the simplest disaccharide substrate without a 6-sulphated aglycone residue. The effect of incubation pH on enzyme activity towards the variety of substrates evaluated was complex and dependent on substrate aglycone structure, substrate concentration, buffer type and the presence of other proteins. Sulphate and phosphate ions and a number of substrate and product analogues were potent inhibitor of form A and form B enzyme activities.     

Geometric design improvements for femoral graft-artery junctions mitigating restenosis

The present study is based on the hypothesis that nonuniform hemodynamics, represented by large time-averaged wall shear stress gradients, trigger abnormal biological processes leading to rapid restenosis, i.e. excessive tissue overgrowth and renewed plaque formation, and hence early graft failure. It implies that this problem may be significantly mitigated by finding graft-artery bypass configurations for which the wall shear stress gradient is approximately zero and hence nearly uniform hemodynamics is achieved. These fluid flow and geometric design considerations are applied to four different end-to-side anastomoses for the distal end of a femoral artery bypass with an appropriate test input pulse and a typical 20–80 flow division. A validated finite-volume code has been used to compute the transient three-dimensional velocity vector fields, wall shear stress distributions and surface contours of the wall shear stress gradients. It is shown that large anastomotic flow areas, small continuously changing bifurcation angles, and smooth junction wall curvatures reduce local time-averaged wall shear stress gradients significantly and hence should mitigate restenosis.     

Aggregation and Metal-Binding Properties of Mutant Forms of the Amyloid Aβ Peptide of Alzheimer's Disease

Abstract: The fibrillogenic properties of Alzheimer's Aβ peptides corresponding to residues 1–40 of the normal human sequence and to two mutant forms containing the replacement Ala²¹ to Gly or Glu²² to Gln were compared. At pH 7.4 and 37°C the Gln²² peptide was found to aggregate and precipitate from solution faster than the normal Aβ, whereas the Gly²¹ peptide aggregated much more slowly. Electron microscopy showed that the aggregates all had fibrillar structures. Circular dichroism spectra of these peptides revealed that aggregation of the normal and Gln²² sequences was associated with spectral changes consistent with a transformation from random coil to β sheet, whereas the spectrum of the Gly²¹ peptide remained almost unchanged during a period in which little or no aggregation occurred. When immobilised by spotting onto nitrocellulose membranes the peptides bound similar amounts of the radioisotope ⁶⁵Zn²⁺. Of several competing metal ions, tested at 20× the concentration of Zn²⁺, Cu²⁺ displaced >95% of the radioactivity from all three peptides and Ni²⁺ produced >50% displacement in each case. Some other metal ions tested caused lesser displacement, but Fe²⁺ and Al³⁺ were without effect. In a saturation binding assay, a value of 3.2 µM was obtained for the binding of Zn²⁺ to Aβ but our data provided no evidence for a reported higher affinity site (107 nM). The results suggest that the neuropathology associated with the Gly²¹ mutation is not due to enhanced fibrillogenic or different metal-binding properties of the peptide and that the binding of zinc to amyloid peptides is not a specific phenomenon.