Distinct pathogenic effects of group B coxsackieviruses on human glomerular and tubular kidney cells.

The six group B coxsackieviruses (CVBs) are highly prevalent human pathogens that cause viremia followed by involvement of different organs. Clinical and experimental evidence suggests that CVBs can induce kidney injury, but the susceptibility of human renal cells to these viruses is unknown. By using pure cultures of human glomerular and tubular cells, we demonstrated that all CVBs are capable of productively infecting renal cells of three different histotypes. Distinct pathogenic effects were observed. Proximal tubular epithelial cells and, to a lesser extent, glomerular podocytes were highly susceptible to CVBs; in both cases, infection led to cytolysis. In contrast, glomerular mesangial cells supported the replication of the six CVBs but failed to develop overt cytopathologic changes. Mesangial cells continued to produce infectious progeny for numerous serial subcultures (i.e., more than 50 days), especially with type 1, 3, 4, and 5 viruses. In the above cells, persistent infection induced the de novo synthesis of platelet-derived growth factor A/B and enhanced the release of transforming growth factor beta1/2. These two factors are important mediators of progression from glomerular inflammation to glomerulosclerosis. CVB replication appeared also to impair the phagocytic and contractile activity of mesangial cells. Loss of these properties--which are important in glomerular physiopathology--may contribute to the development of progressive nephropathy. The results show that CVBs induce distinct effects in different types of cultured renal cells and suggest that CVB infections may be associated with both acute and progressive renal injury.     

Capillary recruitment and transit time in the rat lung

Presson, Robert G., Jr., Thomas M. Todoran, Bracken J. DeWitt, Ivan F. McMurtry, and Wiltz W. Wagner, Jr.Capillary recruitment and transit time in the rat lung.J. Appl. Physiol. 83(2): 543-549, 1997.Increasing pulmonary blood flow and the associated rise incapillary perfusion pressure cause capillary recruitment. The resultingincrease in capillary volume limits the decrease in capillary transittime. We hypothesize that small species with relatively high restingmetabolic rates are more likely to utilize a larger fraction ofgas-exchange reserve at rest. Without reserve, we anticipate thatcapillary transit time will decrease rapidly as pulmonary blood flowrises. To test this hypothesis, we measured capillary recruitment andtransit time in isolated rat lungs. As flow increased, transit timedecreased, and capillaries were recruited. The decrease in transit timewas limited by an increase in the homogeneity of the transit time distribution and an increased capillary volume due, in part, to recruitment. The recruitable capillaries, however, were nearly completely perfused at flow rates and pressures that were less thanbasal for the intact animal. This suggests that a limited reserve ofrecruitable capillaries in the lungs of species with high restingmetabolic rates may contribute to their inability to raiseO₂ consumption manyfold abovebasal values.

     

Posterior dental size reduction in hominids: The Atapuerca evidence

In order to reassess previous hypotheses concerning dental size reduction of the posterior teeth during Pleistocene human evolution, current fossil dental evidence is examined. This evidence includes the large sample of hominid teeth found in recent excavations (1984–1993) in the Sima de los Huesos Middle Pleistocene cave site of the Sierra de Atapuerca (Burgos, Spain). The lower fourth premolars and molars of the Atapuerca hominids, probably older than 300 Kyr, have dimensions similar to those of modern humans. Further, these hominids share the derived state of other features of the posterior teeth with modern humans, such as a similar relative molar size and frequent absence of the hypoconulid, thus suggesting a possible case of parallelism. We believe that dietary changes allowed size reduction of the posterior teeth during the Middle Pleistocene, and the present evidence suggests that the selective pressures that operated on the size variability of these teeth were less restrictive than what is assumed by previous models of dental reduction. Thus, the causal relationship between tooth size decrease and changes in food-preparation techniques during the Pleistocene should be reconsidered. Moreover, the present evidence indicates that the differential reduction of the molars cannot be explained in terms of restriction of available growth space. The molar crown area measurements of a modern human sample were also investigated. The results of this study, as well as previous similar analyses, suggest that a decrease of the rate of cell proliferation, which affected the later-forming crown regions to a greater extent, may be the biological process responsible for the general and differential dental size reduction that occurred during human evolution. © 1995 Wiley-Liss, Inc.     

Somatic expansion of the (CAG) n repeat in Huntington disease brains

The mutation causing Huntington disease (HD) has been identified as an expansion of a polymorphic (CAG) _n repeat in the 5 part of the huntingtin gene. The specific neuropathology of HD, viz. selective neuronal loss in the caudate nucleus and putamen, cannot be explained by the widespread expression of the gene. Since somatic expansion is observed in affected tissue in myotonic dystrophy, we have studied the length of the (CAG) _n repeat in various regions of the brain. Although we have not found clear differences when comparing severely and mildly affected regions, we have observed a minor increase in repeat length upon comparison of affected brain samples with cerebellum or peripheral blood. Hence, although further somatic amplification seems to occur in affected areas of the brain, the differences between affected and unaffected regions are too small to make this mechanism an obvious candidate for the cause of differential neuronal degeneration in HD.     

Therapy of bovine ocular squamous-cell carcinoma with local doses of interleukin-2: 67% complete regressions after 20 months of follow-up

We have tested the therapeutic potency of peritumorally injected low doses of interleukin-2(IL-2). Seventy tumours of the bovine ocular squamous-cell carcinoma (BOSCC), 1–3 cm in diameter, were treated with 5000, 20 000 or 200 000 U IL-2 from Eurocetus (Chiron) to find the optimal dose for treatment. Injections were given peritumorally on Monday to Friday on 2 consecutive weeks. The size of the tumours was measured before treatment and 1, 3, 4, 9 and 20 months after treatment. After 9 months complete regression was observed in 89% of the tumours treated with 5000 U IL-2, 80% treated with 20 000 U and 67% treated with 200 000 U. After 20 months, there was complete regression of 35%, 31% and 67% of the tumours respectively. The 9-and 20-month results of the 200 000-U treatment are significantly better than those of the 5000-U and 20 000-U treatments taken together. This protocol may be useful to treat advanced inoperable tumours (e.g. of the nasopharynx or skin) of human patients.     

DNA fingerprint analysis for the detection of induced mutations in mammalian cells in culture

A mutation assay in cultured mammalian cells based on the direct analysis of minisatellite DNA was developed. Band pattern variations reflect DNA alterations ranging from single base changes to complex rearrangements. By DNA fingerprinting a large number of autosomal loci throughout the human genome can be simultaneously checked, therefore minimizing the size of the samples of cell colonies to be scored in the absence of phenotypic selection. For the mutation assay chinese hamster cells (V79) were treated with Nitrosoguanidine and 14 independent colonies were isolated and expanded. DNA fingerprints were obtained after digestion of the DNA extracted from each clone with bothHinfI andHae III, and hybridisation with both 33.15 and 33.6 probes. Twelve colonies from untreated cells were also analysed. Several differences in the band pattern of treated colonies were observed when compared with untreated cells; digestion withHae III and hybridisation with 33.15 probe allowed the detection of the highest frequency of induced variants. The results suggest that minisatellite sequences are hypermutable sites that can be used to monitor the mutagenic potential of chemical agents directly at the DNA level, without phenotypic selection. Moreover, with the method herein decribed, it is possible to distinguish between true mutations and epimutations, such as those caused by changes in DNA methylation.     

Molecular cloning and functional expression of bacteriophage PK1E-encoded endoneuraminidase Endo NE

Homopolymeric α-2,8-linked sialic acid (PSA) has been found as a capsular component of sepsis- and meningitis-causing bacterial pathogens, and on eukaryotic cells as a post-translational modification of the neural cell adhesion molecule (NCAM). The polysaccharide is specifically recognized and degraded by a phage-encoded enzyme, the endo-N-acetylneuraminidase E (Endo NE). Endo NE therefore has become a valuable tool in the study of bacterial pathogenesis and eukaryotic morphogenesis. In this report we describe the molecular cloning of Endo NE and the expression of a functionally active recombinant enzyme. The cloned DNA sequence (2436 bp) encodes a polypeptide of 811 amino acids, which at the 5′ end contains a totally conserved neuraminidase motif. Expressed in Escherichia coli, the enzyme migrates as a single band of approximately 74 kDa in SDS-PAGE. A central domain of 669 amino acid residues is about 90% homologous to the recently cloned Endo NF. Both phage-induced lysis of bacteria and the catalysis of PSA degradation by the recombinant enzyme are efficiently inhibited by a polyclonal antiserum raised against the intact phage particle. The C-terminal region seems to be essential to enzymatic functions, as truncation of 32 amino acids outside the homology domain completely abolishes Endo NE activity. Our data also indicate that the 38 kDa protein, previously assumed to be a subunit of the Endo NE holoenzyme, is the product of a separate gene locus and is not necessary for in vitro depolymerase activity.     

Effects of metal speciation on growth of phytoplankton with special reference to iron

This paper is a compilation of studies concerning the effects of metal speciation on the growth of phytoplankton. Special attention is paid to the speciation and availability of iron in lake Tjeukemeer, The Netherlands. Under laboratory conditions the free ionic metal species generally appear to be most effective in determining metal availability and toxicity. A variety of factors controlling solubility, ion-exchange, complexation or chelation, sorption and electrostatical attraction of metal ions affect the metal speciation, mostly resulting in reduced availabilities. However, some organic metal chelates such as citrates, nitrillotriacetates and the specifically iron chelating siderophores, are sometimes more available than the corresponding free ions. The presence of other metals also influences the availability of a given metal by competing for the same binding sites on the algal cell. This competition leads to antagonism betweene.g. iron nutrition and cadmium toxicity in marine diatoms. In the eutrophic, alkaline, hard and humic lake Tjeukemeer, the free Fe³⁺ concentration is below measurable levels and does not match the iron requirement of the phytoplankton. So most of the algal iron must have been provided by the predominant inorganic iron colloids and particles bye.g. dissolution or photo-degradation (reduction). If the provision rates of available iron are slow in relation to that of iron uptake, the growth of some phytoplankton species may become iron-limited. Continuous culture work indicated that the iron fraction <0.2 m from Tjeukemeer,i.e., the soluble fraction, is about one third as much available as iron from NH₄Fe(SO₄)₂.12H₂O. Different phytoplankton species vary widely in their metal requirements and tolerances. Therefore, metal speciation and availability may affect species composition and succession within phytoplankton communities. So far the assessment of metal availability in natural waters has been complicated by the complex metal chemistry and by methodological limits.     

A comparative dynamic study of the effectiveness of gastric cytoprotection by vitamin A, De-Nol, sucralfate and ulcer healing by pirenzepine in patients with chronic gastric ulcer (a multiclinical and randomized study)

The gastric cytoprotective effects of vitamin A, De-Nol and sucralfate were compared with the effectiveness of pirenzepine in healing ulcer in patients with chronic gastric ulcer. A total of 100 patients was randomized into different groups: the patients were treated with antacids, vitamin A (3 X 50.000 IU), De-Nol liquid (4 X 5 ml), sucralfate (4 X 1 g) or pirenzepine (3 X 50 mg). The treatment was continued for 4 weeks. At the beginning, 2 and 4 weeks after starting treatment the patients were subjected to endoscopy and the size of the ulcer was measured planimetrically. The ulcer-healing effect of De-Nol liquid was significantly better than that of the antacids (p less than 0.01). Ulcer size was reduced significantly in all groups (p less than 0.01), however, at the end of the study the gastric ulcers were smallest in the De-Nol treated group (p less than 0.001). The dynamics of ulcer healing in the second week was most favourable in the patients receiving vitamin A (p less than 0.01). The present data point to the cytoprotective effects of De-Nol liquid, vitamin A and sucralfate and to their ability of healing chronic gastric ulcers.