Salmonellosis in white-tailed deer fawns

Experimental infection of white-tailed deer fawns with Salmonella meleagridis was accomplished. The fawns suffered clinical illness, similar to spontaneous cases observed in the field. This disease may be an important factor in fawn survival in wild herds based on the frequency with which Salmonellae could be isolated in wild fawns. The clinical disease was acute, characterized by rapid depression and dehydration. Death ensued in three of eight experimental cases. The survivors suffered clinical illness.     

The role of catecholamines and glucagon on serum and liver metallothionein response to restraint stress

The role of glucagon and catecholamines on serum and liver metallothionein (MT) concentrations in basal and stress conditions has been studied. Glucagon showed no effect on serum MT either in basal (unstressed) or stress (20 hours of restraint) conditions. In contrast, glucagon administration increased both unstressed and stressed levels of liver MT. No effect of the alpha + beta-catecholamine blocker labetalol on serum MT levels was observed in unstressed rats. However, the administration of labetalol abolished the increase in serum MT levels caused by stress. These data suggest that catecholamines might be involved in serum MT regulation during stress, while they might not be important in the maintenance of basal serum MT levels. Finally, no significant effect of adrenergic blockade was found on basal and stress levels MT, in agreement with previous data from this laboratory.     

Molecular cloning and DNA sequencing of the Escherichia coli K-12 ald gene encoding aldehyde dehydrogenase.

The gene ald, encoding aldehyde dehydrogenase, has been cloned from a genomic library of Escherichia coli K-12 constructed with plasmid pBR322 by complementing an aldehyde dehydrogenase-deficient mutant. The ald region was sequenced, and a single open reading frame of 479 codons specifying the subunit of the aldehyde dehydrogenase enzyme complex was identified. Determination of the N-terminal amino acid sequence of the enzyme protein unambiguously established the identity and the start codon of the ald gene. Analysis of the 5'- and 3'-flanking sequences indicated that the ald gene is an operon. The deduced amino acid sequence of the ald gene displayed homology with sequences of several aldehyde dehydrogenases of eukaryotic origin but not with microbial glyceraldehyde-3-phosphate dehydrogenase.     

Presence of terminal N-acetylgalactosamine residues in subregions of the endoplasmic reticulum is influenced by cell differentiation in culture.

Using Helix pomatia lectin as a specific probe for terminal, nonreducing N-acetylgalactosamine residues, glycoprotein precursors bearing newly initiated O-linked oligosaccharides have been localized in the lumen of the endoplasmic reticulum and cis-Golgi cisternae. This pattern contrasts with the detection of the terminal disaccharide galactose beta-1,3-N-acetylgalactosamine by Arachis hypogaea lectin in middle and trans-Golgi compartments, which are considered elongation sites for O-glycosylation. Distribution of H. pomatia ligands in the endoplasmic reticulum is confined to specialized regions or subcompartments in both human colonic adenocarcinoma cells and cultured chicken chondrocytes. Since in cartilage, chondrocytes contain H. pomatia-binding sites exclusively concentrated in cis-Golgi cisternae, primary cultures of this cell type have been used to study those conditions that promote initiation of O-glycosylation in the endoplasmic reticulum. A correlation has been found between the age of the culture and the extent of reactivity of the endoplasmic reticulum with either H. pomatia lectin or antibody against the sequence GalNAc alpha-serine/threonine (Tn antigen). Cells showing an extensive reaction are not hindered in their secretory activity and still maintain the chondrocyte phenotype. Taken together the results suggest that the intracellular distribution of the glycosylation enzymes is not only cell type-specific as previously shown (Roth, J., Taatjes, D. J., Weinstein, J., Paulson, J. C., Greenwell, P., and Watkins, W. M. (1986) J. Biol. Chem. 261, 14307-14312) but it might also vary depending on the stage of cell differentiation.     

Detection of glycosaminoglycans in the Golgi complex of chondrocytes

Elongation and sulfation of glycosaminoglycans are pivotal roles of the Golgi complex during the biosynthesis of proteoglycan monomers. In the present work the spatial relationship between these processes has been investigated by using a combination of immunocytochemical and cytochemical techniques. Chondroitin sulfate and keratan sulfate glycosaminoglycans were immunocytochemically localized in 1 to 2 transmost cisternae, also in a system of narrow tubules at the trans face of the Golgi complex of chick epiphyseal chondrocytes. At these same locations sulfate groups were revealed with the high iron diamine (HID) method, proteoglycan monomers being visualized with ruthenium red. Several treatments were assayed in order to reversibly block the secretory pathway. Chondrocytes incubated at a low temperature, 15 degrees C, before fixation, showed both glycosaminoglycans in the middle cisternae of the Golgi stack as well as the above mentioned locations. After low temperature treatment both HID and ruthenium red stained the middle, but not the cis cisternae. Incubation of the cells for 30 min with either diethylcarbamazine or monensin before fixation permitted detection of glycosaminoglycans and proteoglycan monomers in the middle cisternae, whereas HID staining of the Golgi complex, but not that of secretory vesicles, was abolished. The results show that elongation of both chondroitin sulfate and keratan sulfate glycosaminoglycans takes place in the same Golgi compartments. These include the middle cisternae and probably also the trans cisternae and tubules. Also suggested is that sulfation of one or both types of glycosaminoglycans begins in the middle cisternae.     

Inositol trisphosphate and excitation-contraction coupling in skeletal muscle

The role of inositol trisphosphate as a chemical messenger in excitation-contraction coupling is discussed, both in terms of positive and negative results. The evidence presented includes experiments on the effect of inositol trisphosphate in intact and skinned fibers, in calcium release from isolated sarcoplasmic reticulum vesicles, in activation of single calcium release channels incorporated in planar bilayers, and biochemical experiments that have established the presence of all the intermediate steps involved in the metabolism of phosphoinositides, both in intact muscle and in isolated membranes. From these results, it is clear that a role for inositol triphosphate in skeletal muscle function is highly likely; whether this molecule is the physiological messenger in excitation-contraction coupling remains to be established.     

Phosphorylation of myosin light chain from adrenomedullary chromaffin cells in culture.

The myosin-light-chain (MLC) phosphorylation accompanying catecholamine release in chromaffin cells was investigated with the objective of assessing the possible role of this contractile protein in catecholamine secretion. The electrophoretic characteristics of adrenomedullary MLC were determined by immunochemical techniques using two different specific antibodies. The identified 22 kDa phosphoprotein was mainly present in the cytosol, as demonstrated by ultracentrifugation and immunocytochemical analysis. A part of this protein was located on, or close to, the plasma membrane. Cell stimulation by secretagogues resulted in a Ca2(+)-dependent 32P incorporation into MLC, the time course of this process being related to catecholamine release. These findings were supported by a two-dimensional gel-electrophoretic analysis by which means this protein was resolved into two acidic forms. A role for Ca2(+)-calmodulin and Ca2(+)-phospholipid kinases in adrenomedullary MLC phosphorylation is reported. The results obtained suggest a regulatory role for such a protein in the underlying exocytotic event.     

Echocardiographic assessment and percutaneous closure of multiple atrial septal defects

Percutaneous coronary intervention can be associated with distal embolization of thrombotic material causing myocardial necrosis and infarction. We discuss the role of intravascular imaging to guide the use of a distal protection device by describing the outcome of a young woman presenting with non-ST elevation myocardial infarction. Coronary angiography demonstrated an isolated minor stenosis in the proximal left anterior descending coronary artery with slight haziness beyond the lesion. Intravascular ultrasound confirmed an extensive thrombus overlying a bulky atherosclerotic plaque. A distal filter wire was therefore successfully used to reduce the risk of distal embolization. The use of intravascular ultrasound in patients presenting with acute coronary syndrome may reveal large thrombi that are difficult to image using conventional angiographic techniques. Intravascular ultrasound can therefore be used as a tool to select lesions requiring distal protection.