Interaction ofBdellovibrio with Its prey in mixed microbial populations

The interaction ofBdellovibrio with its prey can be affected by the presence of other microorganisms regardless of whether they serve as a prey for the bdellovibrios. This was shown in a system in which the fate of one prey could be followed in mixed bacterial populations thanks to a specific trait, bioluminescence. The attacking bdellovibrio causes decay of bioluminescence, and the rate of light decay of the population indicates the rate at which the luminous bacteria are attacked. Using this system it was found that different bacteria affected the predatorprey interaction in different ways: some competed with the original prey for the predator; others enhanced the activity of the predator toward the original prey, and others inhibited it. The significance of these findings in relation to the distribution and activity ofBdellovibrio in the natural ecosystem is discussed.     

Neuronal survival in intact ciliary ganglia in vivo and in vitro: Ciliary neuronotrophic factor as a target surrogate

Ciliary neuronotrophic factor (CNTF) requirements for neuronal survival in the intact ciliary ganglion (CG) have been investigated in organ culture. Exogenous CNTF was not essential for neuronal survival until embryonic Day 8. Three-day cultures from 5-day ganglia were similar with or without CNTF, showing numerous neurons and extensive neuritic development. In 3-day cultures from 8-day-old ganglia, however, no neurons survived without CNTF, and the ganglia contained only nonneuronal cells and cell debris. Similar ganglia cultured with CNTF contained many neurons, surrounded by nonneuronal cells, and abundant neuritic processes. Morphologic maturation of the neurons was less advanced in CNTF-supported ganglia than in their in vivo counterparts.     

An enzyme-linked immunosorbent assay for bromodeoxyuridine incorporation using fixed microcultures

We report a quantitative method by which a single microculture can be examined for (i) cell morphology; (ii) cell number; (iii) DNA synthesis; and (iv) expression of cell antigens. This method first involves measuring by enzyme-linked immunosorbent assay (ELISA) the total bromodeoxyuridine (BrdU) incorporation into DNA by monolayer microcultures. The BrdU-ELISA measurement was followed by simultaneous immunostaining for BrdU-positive nuclei and for a cytoplasmic antigen. The method was applied to the measurement of mitogen-induced proliferation of rat sciatic nerve Schwann cell and cerebral astroglia microcultures. The ELISA measurement of BrdU incorporation compares favorably with measurements of tritiated thymidine incorporation and offers the additional advantages that the same microculture can subsequently be examined for cell number, for cell morphology, and for the percentage of cells having BrdU-labeled nuclei and other antigens.     

Evidence for the deficiency of β-glucosidase-activating factor in fibroblasts of patients with I-cell disease

Summary Reduced activity of -glucosidase was shown in the cultured skin fibroblasts of four patients with I-cell disease when the enzyme was tested without the use of detergents. In the presence of taurocholate and triton X100 -glucosidase activity was normal. This suggested a deficiency of a -glucosidase-activating factor in I-cell fibroblasts rather than of the enzyme itself. The deficiency of -glucosidase activity was corrected to some extent by mixing cell lysates, and more effectively by cocultivation and fusion of I-cell disease and Gaucher fibroblasts. These results present evidence for the presence of a -glucosidase-activating factor in normal and Gaucher fibroblasts. In fibroblasts of patients with I-cell disease this activator is probably deficient, as is the case for most lysosomal enzymes.     

Mutually Independent Cyclic AMP and Sodium Responses to Nerve Growth Factor in Embryonic Chick Dorsal Root Ganglia

Abstract: Chick embryo dorsal root ganglia display a rapid and transient rise in their cyclic AMP content when presented with nerve growth factor. These ganglia also depend on nerve growth factor for control of their intracellular Na⁺ and K⁺ levels. A sequential relationship between the cyclic AMP and Na⁺ responses is not readily apparent. Incubation of chick sensory ganglia in a sodium-free medium does not prevent the cyclic AMP response to nerve growth factor from occurring. When ganglia are first incubated with ouabain for 6 h, presentation of nerve growth factor elicits a cyclic AMP response, but no Na⁺ response. The cyclic AMP response therefore does not depend on the Na⁺ environment. An initial presentation of nerve growth factor to the ganglia for 30 min, followed by its withdrawal and subsequent re-administration at different intervals over several hours failed to result in a second cyclic AMP response. Nevertheless, the expected Na⁺ behaviors were still observed. Dibutyryl cyclic AMP is capable of eliciting a cyclic AMP response in chick sensory ganglia after 6 h of nerve growth factor deprivation. When both agents were presented simultaneously to the ganglia, only a single cyclic AMP response was obtained, corresponding in time to the response elicited by dibutyryl cyclic AMP alone-indicating that this drug acts on the NGF-sensitive cells. At the same time dibutyryl cyclic AMP alone failed to result in a Na⁺ response, leading one to conclude that the cyclic AMP response to nerve growth factor is truly not mediating the Na⁺ response. Additional support for the mutual independence of these two short-latency responses is provided by the apparent inability of nerve growth factor to cause a cyclic AMP response in chick embryo sympathetic ganglia, another traditional target for the factor, which is capable of displaying a Na⁺ response.     

Properties of marine bdellovibrios

Marine bdellovibrio isolates from the Israeli littoral of the Mediterranean Sea were screened and characterized in terms of host range, temperature and salinity ranges, cation requirement, mutation frequency, and G + C% mole content. Ten types of isolates were distinguished on the basis of these parameters.     

Successful bone marrow transplantation in a patient with DNA ligase IV deficiency and bone marrow failure

Cirrhotic cardiomyopathy is the term used to describe a constellation of features indicative of abnormal heart structure and function in patients with cirrhosis. These include systolic and diastolic dysfunction, electrophysiological changes, and macroscopic and microscopic structural changes. The prevalence of cirrhotic cardiomyopathy remains unknown at present, mostly because the disease is generally latent and shows itself when the patient is subjected to stress such as exercise, drugs, hemorrhage and surgery. The main clinical features of cirrhotic cardiomyopathy include baseline increased cardiac output, attenuated systolic contraction or diastolic relaxation in response to physiologic, pharmacologic and surgical stress, and electrical conductance abnormalities (prolonged QT interval). In the majority of cases, diastolic dysfunction precedes systolic dysfunction, which tends to manifest only under conditions of stress. Generally, cirrhotic cardiomyopathy with overt severe heart failure is rare. Major stresses on the cardiovascular system such as liver transplantation, infections and insertion of transjugular intrahepatic portosystemic stent-shunts (TIPS) can unmask the presence of cirrhotic cardiomyopathy and thereby convert latent to overt heart failure. Cirrhotic cardiomyopathy may also contribute to the pathogenesis of hepatorenal syndrome. Pathogenic mechanisms of cirrhotic cardiomyopathy are multiple and include abnormal membrane biophysical characteristics, impaired β-adrenergic receptor signal transduction and increased activity of negative-inotropic pathways mediated by cGMP. Diagnosis and differential diagnosis require a careful assessment of patient history probing for excessive alcohol, physical examination for signs of hypertension such as retinal vascular changes, and appropriate diagnostic tests such as exercise stress electrocardiography, nuclear heart scans and coronary angiography. Current management recommendations include empirical, nonspecific and mainly supportive measures. The exact prognosis remains unclear. The extent of cirrhotic cardiomyopathy generally correlates to the degree of liver insufficiency. Reversibility is possible (either pharmacological or after liver transplantation), but further studies are needed.     

Genomic rearrangements at the <Emphasis Type="Italic">IGHMBP2</Emphasis> gene locus in two patients with SMARD1

Autosomal recessive spinal muscular atrophy with respiratory distress type 1 (SMARD1) is caused by mutations in the immunoglobulin -binding protein 2 (IGHMBP2) gene. Patients affected by the infantile form of SMARD1 present with early onset respiratory distress. So far, patients with neither juvenile onset nor with larger deletions/rearrangements in IGHMBP2 have been reported. In this study, we investigated one patient with infantile (4 months) and another with juvenile (4.3 years) onset of respiratory distress. Direct sequencing of all exons and flanking intron sequences in both patients revealed a mutation on only one allele. In both patients, we identified genomic rearrangements of the other allele of IGHMBP2 by means of Southern blotting. Putative breakpoints were confirmed by polymerase chain reaction on genomic and cDNA. The patient with juvenile onset had an Alu/Alu mediated rearrangement, which resulted in the loss of ~18.5 kb genomic DNA. At the mRNA level, this caused an in-frame deletion of exons 3–7. The patient with infantile onset had a complex rearrangement with two deletions and an inversion between intron 10 and 14. This rearrangement led to a frameshift at the mRNA level. Our results show that SMARD1 can be caused by genomic rearrangements at the IGHMBP2 gene locus. This may be missed by mere sequence analysis. Additionally, we demonstrate that juvenile onset SMARD1 may also be caused by mutations of IGHMBP2. The complex nature of the genomic rearrangement in the patient with infantile SMARD1 is discussed and a deletion mechanism is proposed.