Traumatic disruption of the fibrous skeleton of the heart, with injury of the tricuspid and mitral valves, aortic annulus, and ventricular septum

In an automobile accident, a young man sustained blunt trauma to the chest that caused injury to the fibrous skeleton of the heart. The mitral and tricuspid valves and their annuli were lacerated, the aortic annulus was separated from the ventricular septum, and the ventricular septum was disrupted; however, with surgical management, the patient survived.     

Persistence and spread of a chloramphenicol resistance-mediating plasmid in antigenic types of Escherichia coli, pathogenic for piglets

All chloramphenicol-resistant Escherichia coli strains isolated from piglets in the State veterinary Serum Laboratory, Copenhagen, in 1974-1975 harbored plasmids of IncFII group with largely the same resistance markers. Two strains from 1978 carried plasmids with similar characters. Restriction enzyme analysis of DNA from these plasmids with restriction endonucleases EcoRI, BglII, and PstI shows that the Cm plasmids are extremely closely related; but the patterns obtained (particularly from PstI digests) enable the classification of the plasmids into groups. These bear a strong relation to time and place of isolation so that plasmids isolated on the same farm belong to the same group even when their host strains are of different antigenic types. It is concluded that these plasmids have evolved from a single plasmid.     

Developmental Parameters of Mother-Offspring Interactions in Acomys cahirinus

Developmental parameters of mother-infant interactions in Acomys cahirinus were investigated in a series of observational and experimental studies. The uniquely precocial offspring associated closely with both parents beyond the time of weaning and birth of the next litter. The survival rate of foster pups was dependent upon both the age of the pups and the physiological stare of the foster mothers. While 1 and 8-day post partum ♂♂ nursed unfamiliar neonates as frequently as their own pups, they interacted with unfamiliar 8-day-old offspring less than with their own.     

Incorporation of l-[3H]fucose and d-[3H]glucosamine into cell-surface-associated glycoconjugates in epidermis of cultured pig skin slices.

1. Electron microscope autoradiography indicated that L-[3H]fucose and D-[3H]glucosamine were both incorporated into cell-surface-associated glycoconjugates in the epidermis of cultured pig skin slices. 2. Acid hydrolysis and paper chromatography of skin homogenates confirmed that there was little metabolic conversion of the labeled precursors to other sugars. 3. Epidermis was separated from dermis using CaCl2, and was extracted with 8 M-urea/5% (w/v) sodium dodecyl sulphate and was then analysed by gel electrophoresis. The major component labelled with D-[3H]glucosamine had an apparent molecular weight in excess of 200 000. This material was not labelled with L-[3H]fucose. Lower molecular-weight components were labelled to a similar extent with both L-[3H]fucose and D-[3H]glucosamine. 4. The high molecular-weight material labelled with D-[3H]glucosamine was released into the medium when the epidermal cells were dispersed with trypsin, indicating that it was either surface-associated or was extracellular. It was also labelled with D-[14C]glucuronic acid, 35SO4(2-) and to a small extent with 14C-labelled amino acids indicating that it contained glycosaminoglycans derived from epidermal proteoglycans. This was confirmed by the fact that it was degraded by testicular hyaluronoglucosidase. It was not present in isolated membranes but was recovered in the soluble fraction from epidermal homogenates. It is therefore only very loosely bound at the cell surface or is present in the extracellular spaces. 5. Membrane-bound [3H]glycoproteins were identified after differential centrifugation of epidermal homogenates. The radioactivity profiles of membrane glycoproteins were similar whether L-[3H]fucose or D-[3H]glucosamine were used and both consisted of a major heterogeneous peak in the apparent mol.wt. range 70 000--150 000. [3H]Glycoproteins in this molecular-weight range were also major components of a plasma-membrane-enriched fraction. These glycoproteins were probably bound to the membrane by hydrophobic interactions, since they were only solubilized by treatment with detergent or organic solvent. They contained terminal sialic acid residues, since they were degraded by neuraminidase.     

Spore Load of Ascosphaera Species on Emerging Adults of the Alfalfa Leafcutting Bee, Megachile rotundata

The spore load of Ascosphaera species spores on larval chalkbrood cadavers and newly emergent adults of the alfalfa leafcutting bee, Megachile rotundata, was determined. The spore content of chalkbrood cadavers ranged from 3 × 10⁶ to 5 × 10⁸. Adults emerging through zero to nine cadavers carried spores on all body parts examined by scanning electron microscopy. Estimates of the total number of spores obtained from a series of adult washes ranged from 9 × 10⁴ to 8 × 10⁷. Some adult males which emerged through no cadavers carried 10⁴ to 10⁵ spores, indicating that nesting materials might also have been contaminated. However, the control of chalkbrood in commercial bee populations may not be accomplished simply by providing clean nesting materials as adults may still emerge through diseased larvae.     

A steady-state kinetic study on the catalytic mechanism of ribulose bisphosphate carboxylase from soybean

The catalytic mechanism of soybean ribulose bisphosphate carboxylase was examined, through a study of the steady-state kinetic behavior of the fully activated enzyme using short time assays. The effects of substrates, products, alternative products, and two dead-end inhibitors were investigated. High concentrations of both substrates were observed to lead to nonhyperbolic relationships: concentrations of bicarbonate greater than 15 mm inhibited and concentrations of ribulose bisphosphate greater than 0.2–0.5 mm stimulated enzyme activity over that expected from a hyperbolic fit to the data. The kinetic patterns obtained and the nonhyperbolic behavior of substrates are interpreted to suggest that the binding of substrates and the release of products follow a steady-state random mechanism. The substrate activation by ribulose bisphosphate is likely to be physiologically significant.     

The molt cycle and its hormonal control in Rhithropanopeus harrisii larvae

Stages of the zoeal and megalopal molt cycles of Rhithropanopeus harrisii were characterized by the appearance of epidermal cells in the spines and antennae. Eyestalk removal of the beginning of the last zoeal instar slightly accelerated the molt cycle. Fourth-instar larvae which had undergone eyestalk ablation during the third instar progressed through the molt cycle significantly faster than did control larvae. Eyestalkless megalopae also demonstrated an enhanced molting rate. The results suggested that the larval eyestalks contain a factor (molt-inhibiting hormone) which plays a role in controlling the molting rate.     

Characterization of human blood platelet membrane proteins and glycoproteins by their isoelectric point (pI) and apparent molecular weight using two-dimensional electrophoresis and surface-labelling techniques

Intact human blood platelets were radioactively labelled at the surface by techniques specific for proteins or glycoproteins. Labelled platelet samples were analyzed by a high-resolution two-dimensional separation system involving isoelectric focusing in the first dimension and discontinuous sodium dodecyl sulphate-polyacrylamide gel electrophoresis in the second. The major platelet membrane glycoprotein (GP) bands (Ib, IIb, IIIa and IIIb) were found to be highly heterogeneous even after removal of terminal sialic acid residues. Lactoperoxidase-catalyzed iodination of platelets showed that the major labelled proteins (Ib, IIb, IIIa and IIIb) had altered isoelectric points ($\text{p}\text{I}$) and molecular weights after neuraminidase treatment. A number of membrane glycoproteins previously undetected by one-dimensional gel electrophoresis were demonstrated and good evidence provided that the major platelet surface proteins are glycosylated.