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Biomedical subjects

J Rossi

Publications and source records attributed to J Rossi.

At least 73 records · Page 4Linked to original sources
PubMed1996

An overview of the development, validation, and application of neurobehavioral and neuromolecular toxicity assessment batteries: potential applications to combustion toxicology.

Currently, there are few alternatives to the use of animals in toxicology for human risk assessment. Neurobehavioral toxicology is an emerging area in which complex performance capacity is evaluated during or following toxicological exposure. While a number of single tests and a few more complex neurobehavioral batteries exist, no fully validated and comprehensive neurobehavioral toxicity assessment battery has yet been developed. The Neurobehavioral Toxicity Assessment Battery (NTAB) is a multi-test battery being developed by the Naval Medical Research Institute Detachment (Toxicology) (NMRI/TD) to categorize the potential neurobehavioral toxicity of compounds of Navy interest, especially those found in combustion atmospheres. The NTAB is intended to identify specific areas of deficit (e.g. motivational, sensory, motor, and cognitive) from complex changes in performance induced by toxic exposures, as well as to provide a mechanism to evaluate recovery of neurobehavioral integrity. Portions of the NTAB have been successfully used to assess the risk of brief exposure to low concentrations of combustion gases, including smoke from electrical aircraft fires, ozone-depleting substances and their replacements, and the novel neuroconvulsant trimethylolpropane phosphate. The goal of the NMRI/TD Neurobehavioral Toxicology Group and the Tri-Service Toxicology Consortium's neurobehavioral toxicology program is the incorporation of more molecular techniques involving neurophysiology, neuropharmacology, in vivo electrochemistry, and real-time microdialysis for correlative use with the neurobehavioral battery in human risk assessment. This overview discusses the application of neurobehavioral and neuromolecular endpoint test batteries to combustion toxicology.

Animals↗
PubMed1996

Sensitization induced by kindling and kindling-related phenomena as a model for multiple chemical sensitivity.

It has been suggested that the neurobehavioral dysfunction observed in persons presenting with symptoms of Multiple Chemical Sensitivity (MCS) syndrome involves sensitization of neural circuits. Two hypotheses for the route of exposure in induction of neural sensitization in MCS are: (a) direct chemical stimulation of olfactory processes, or (b) general systemic response to inhaled chemicals. In either case, the mechanism of action may involve chemical kindling or kindling-related phenomena. A neural sensitization mechanism based on kindling or kindling-related phenomena is attractive and has been previously demonstrated in both in vitro and in vivo animal models. Without a testable animal model for chemically mediated induction of MCS, however, any argument that MCS is mediated by kindling or kindling-related phenomena is reduced to the circular argument "the mechanism of sensitization is sensitization." The present survey provides an overview of the experimental paradigms that result in sensitization, differentiated on the basis of probable neurophysiological and neurochemical mechanisms. Neurophysiological potentiation, electrical kindling, chemical kindling and behavioral sensitization are evaluated and discussed in relationship to MCS.

Animals↗
PubMed1996

Tandem triplication and quadruplication of chromosome 21 in childhood acute lymphoblastic leukemia.

A 5-year-old girl with ALL was shown to have a leukemic clone characterized by a triplication and quadruplication of chromosome 21, arranged in tandem, at diagnosis and relapse, respectively. To our knowledge, this is the second report of this chromosomal anomaly in ALL, which was confirmed by in situ staining. The karyotype evolution in the leukemic clone from triplication to quadruplication at relapse emphasizes the association of chromosome 21 with hematopoietic malignancies.

Aneuploidy↗
PubMed1995

Ribozyme-mediated inhibition of expression of leukocyte-type 12-lipoxygenase in porcine aortic vascular smooth muscle cells.

Activation of a leukocyte-type 12-lipoxygenase (12-LO) has been proposed to be an important mechanism for angiotensin II- and glucose-induced vascular smooth muscle cell growth. Currently, no specific pharmacological inhibitors for the leukocyte-type 12-LO are available to test this hypothesis. We have therefore designed a chimeric DNA-RNA hammerhead ribozyme to produce cleavage at the first GUC sequence at nucleotide 7 of porcine leukocyte 12-LO mRNA. The ribozyme was tested in vitro with a 206-base 12-LO mRNA as substrate. We observed that the ribozyme specifically and dose-dependently cleaved porcine leukocyte 12-LO mRNA at the predicted site under physiological temperature. Furthermore, we also efficiently delivered the ribozyme into porcine aortic vascular smooth muscle cells by transfection with cationic liposomes. The ribozyme caused a dose-dependent decrease in levels of porcine leukocyte-type 12-LO mRNA in these cells and was more potent than an antisense oligonucleotide directed against porcine leukocyte 12-LO. The 12-LO ribozyme also attenuated 12-LO protein levels in the cells. The action of the ribozyme was primarily a result of its catalytic activity, since a modified ribozyme that lacks catalytic activity showed reduced effects. This represents the first ribozyme directed against a mammalian LO pathway. These results demonstrate the potential utility of new ribozyme technology to generate novel agents for gene modulation experiments to modify the development or progression of vascular disease in humans.

Animals↗
PubMed1993

Inhibition of human immunodeficiency virus type 1 replication by regulated expression of a polymeric Tat activation response RNA decoy as a strategy for gene therapy in AIDS.

We are investigating a strategy for somatic gene therapy to treat human immunodeficiency virus type 1 (HIV-1) infection by intracellular expression of an RNA decoy and a ribozyme. The RNA decoy, consisting of polymeric Tat activation response elements (TARs), is designed to compete for Tat binding in an equilibrium with viral TAR RNA, thereby inhibiting viral replication. The expression of polymeric TAR is regulated by the HIV long terminal repeat (LTR) and transcriptional activation is dependent on the presence of HIV Tat. Our initial studies indicated that plasmids expressing up to 50 tandem copies of TAR RNA (50TAR) inhibited tat-mediated gene expression by > 90% in a transient transfection assay. A HIV LTR-driven 50TAR construct was subcloned into a replication-defective retroviral vector to ensure high-efficiency gene transfer into T lymphocytes. In addition, a gag RNA-specific ribozyme gene was introduced into the 50TAR containing retroviral vector to enhance the inhibitory effect of the construct (designated TAR-Rib). A human T-cell line (Molt3) was infected (transduced) with the TAR-Rib recombinant retrovirus and challenged with either HIV-1 or simian immunodeficiency virus (SIV). HIV-1 replication was inhibited by 99% in the TAR-Rib-transduced T cells and was maintained over a 14-month period, suggesting that this antiviral strategy represses the formation of escape mutants. Interestingly, the TAR-Rib also inhibited SIV replication in transduced T cells, which suggests that polymeric TAR is a general inhibitor of primate lentiviruses; therefore, the macaque model could be used for further in vivo testing of this antiviral gene therapy strategy.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Elevated glucose and angiotensin II increase 12-lipoxygenase activity and expression in porcine aortic smooth muscle cells.

The lipoxygenase (LO) pathway of arachidonate metabolism has been suggested to play a key role in atherosclerosis and in mediating several actions of angiotensin II (AII). However, the relationship between LO activation and factors linked to accelerated diabetic vascular disease such as hyperglycemia and AII is not known. We have investigated the effect of high glucose (HG; 25 mM) and AII on LO activity as well as LO protein and mRNA expression in porcine aortic vascular smooth muscle cells (PVSMCs). We observed that cells cultured in HG had significantly higher levels of the cell-associated LO products 12- and 15-hydroxyeicosatetraenoic acids (HETEs). AII added to cells grown in HG specifically further increased only cell-associated 12-HETE levels. Using immunoblot analysis and reverse transcriptase PCRs, we demonstrated the presence in PVSMCs of porcine leukocyte-type 12-LO protein and mRNA, respectively. Furthermore, the levels of both were markedly upregulated by AII as well as by HG. These studies suggest that enhanced 12-LO activity and expression are mechanisms for accelerated vascular disease produced by HG and AII in diabetes mellitus.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1992

Analysis of the relationships between self-stimulation sniffing and brain-stimulation sniffing.

Determination of current thresholds for self-stimulation and electrically elicited sniffing from electrodes placed into lateral hypothalamic and ventral tegmental areas of rats revealed a tight correlative relationship between the two phenomena (r values of approx 0.9 at both sites). Thresholds for sniffing were never higher than those for self-stimulation, while approximately half the animals had higher self-stimulation than sniffing thresholds, suggesting that electrically elicited sniffing may better index the underlying psychobiological process that mediates self-stimulation. That both phenomena reflect the same basic process was suggested by the fact that 48 h of food deprivation consistently reduced the thresholds for both self-stimulation and sniffing, while 24 h of food deprivation had only marginal effects on both. The implications for understanding the nature of self-stimulation processes is discussed.

Animals↗
PubMed1992

Peptidase profiles of Pseudomonas fluorescens: identification and properties.

The cell-associated peptidase profiles of 12 strains of Pseudomonas fluorescens (ATCC 948 and 11 related biotypes) were examined. Employing Analytab system API ZYM, a general, strong peptidase activity was detected using L-lysyl-, L-pyrrolidonyl-, L-arginyl-, L-alanyl-, and glycyl-glycyl-beta-naphthylamides as substrates. Conversely, L-tyrosyl-, L-phenylalanyl-, L-histidyl-, L-prolyl-, gamma-L-glutamyl-beta-naphthylamides substrates were hydrolyzed by only a few strains. The peptidases were active, therefore, on substrates responsible for the bitter taste in dairy products. Properties of hydrolytic systems showed no significant changes in the enzymatic profiles when cells were grown on different fermentation media. Enzyme activity was relatively stable during refrigerated (5 degrees C) and frozen (-18 degrees C) storage. The peptidases of P. fluorescens ATCC 948, considered as reference, and strain 22 were identified on Pro-beta-naphthylamides by Michaelis constant values of .528 and .394 mM, respectively, and by different optimal pH and temperature activity on Leu- and Pro-beta-naphthylamides. The peptidase activity on Gly-Phe-beta-naphthylamide in P. fluorescens 30 had optimal values at pH 7.50 and 45 degrees C. These results confirm the relations defined in the enzymatic identification phase and suggest the presence of any analogous peptidases in the biovars of P. fluorescens considered.

Culture Media↗
PubMed1992

[Post-traumatic gas in children. Apropos of a case].

The authors report a case of post-traumatic gas in the portal vein in a child. They stress the rarity of this lesion in such circumstances and recall the radiological signs together with the differential diagnoses and the principal aetiologies.

Accidents, Traffic↗
PubMed1991

Effect of fixation on the amplification of nucleic acids from paraffin-embedded material by the polymerase chain reaction.

Amplification of nucleic acids from paraffin-embedded material by the polymerase chain reaction (PCR) is increasingly being used to detect viral genomes and oncogene mutations. To determine the effect of fixation on the preservation of the nucleic acids, we fixed two randomly chosen fresh pathology specimens in formalin, B-5, Bouin's, Zenker's, ethanol, and Omnifix for 6, 24, 48, 72, and 168 hr (1 week), and then embedded the tissue in paraffin. Oligonucleotide primers specific for the cytoplasmic-beta-actin gene were chosen to span an intron such that amplification yielded a product of 250 BP for DNA and 154 BP for RNA. A single 6-microns section was cut from each paraffin block, deparaffinized, and then subjected to 30 rounds of amplification for either DNA or RNA. On amplifying DNA, consistent product was seen in the ethanol and Omnifix specimens up to 72 hr of fixation time, whereas variable product was seen with formalin or Zenker's fixation; all specimens fixed in Bouin's or B-5 were negative. On amplifying RNA, a product could be detected even after 1 week of fixation in ethanol or Omnifix, and after 48 hr in the formalin-fixed tissue. The Zenker's-fixed tissues gave variable results, and the Bouin's and B-5 tissues gave consistent results only after 6 hr of fixation. We therefore conclude that choice of fixative and fixation time are critical factors influencing the outcome of PCR amplification of nucleic acids from paraffin-embedded material.

Base Sequence↗
PubMed1990

Monocytoid B-cell lymphoma in a patient with human immunodeficiency virus infection. Demonstration of human immunodeficiency virus sequences in paraffin-embedded lymph node sections by polymerase chain reaction amplification.

There is a significantly increased incidence of malignant lymphoma in patients with acquired immunodeficiency syndrome (AIDS). The lymphomas are usually of a high grade and of B-cell phenotype. While the frequent presence of reactive monocytoid B lymphocytes in patients with AIDS-related lymphadenopathy has recently been documented in several studies, to our knowledge, there are no reported cases of monocytoid B-cell lymphoma, the neoplastic counterpart of monocytoid B lymphocytes, in patients with AIDS. We now describe a human immunodeficiency virus (HIV)-positive patient with HIV-related lymphadenopathy in whom monocytoid B-cell lymphoma developed during the course of his disease. The morphologic and immunologic features of the lymphoma were characteristic of monocytoid B-cell lymphoma, and the involved lymph node exhibited a reversed CD4/CD8 ratio. Moreover, using the polymerase chain reaction, we were able to demonstrate HIV genome in DNA extracted from the lymph node tissue. To our knowledge, this is the first report of a case of monocytoid B-cell lymphoma occurring in an HIV-positive patient and in which we were able, by using a sensitive molecular biologic technique, to demonstrate HIV sequence in paraffin-embedded, fixed lymph node sections.

Acquired Immunodeficiency Syndrome↗
PubMed1986

An ancient developmental induction: heat-shock proteins induced in sporulation and oogenesis.

Every eukaryotic and prokaryotic organism tested to date synthesizes a small number of heat-shock proteins in response to heat and other forms of stress. A particular pattern of heat-shock gene expression was observed during ascospore development in Saccharomyces: heat-shock proteins hsp26 and hsp84 were strongly induced nor inducible by heat shock. Instead, two proteins related to hsp70 were induced. A strikingly similar pattern of expression occurs during oogenesis in Drosophila, suggesting that it may be one of the earliest developmental pathways to evolve in eukaryotic cells.

Drosophila↗
PubMed1986

Mutations in conserved intron sequences affect multiple steps in the yeast splicing pathway, particularly assembly of the spliceosome.

Yeast introns contain three highly conserved sequences which are known to be required for splicing of pre-mRNA. Using in vitro mutagenesis, we have synthesized seven point mutations at five different sites in these signals in the yeast actin intron. The mutant introns were then inserted into each of three constructs, which allowed us to assess the consequences both in vivo and in vitro. In virtually every case, we found the efficiency of splicing to be significantly depressed; mature mRNA levels in vivo ranged from 0 to 47% of wild-type. Surprisingly, the tightest mutations were not necessarily at the sites of nucleolytic cleavage and branch formation; these nucleotides are thus highly preferred, but are not absolutely necessary. Moreover, while particular nucleotides are specifically required for the final step in splicing, i.e. 3' cleavage and exon ligation, the predominant consequence of mutation within the conserved signals appears to be the inhibition of assembly of the splicing complex.

Actins↗
PubMed1986

Alpha-amylase and glucoamylase production by Schwanniomyces castellii.

A chromogenic substrate (Cibachron blue-amylose), and soluble starch and maltose were used to characterize the amylolytic system from Schwanniomyces castellii 3754. The strain was able to produce inducible alpha-amylase (EC 3.2.1.1) and glucoamylase (EC 3.2.1.3) when grown on different C sources. The effect of the C source was slightly different for alpha-amylase and glucoamylase production. Melezitose, maltose and soluble starch enhanced both alpha-amylase and glucoamylase synthesis to nearly the same extent; amylose, trehalose and cellobiose particularly induced alpha-amylase synthesis. The optimal pH for the release of both amylases was 5.5-7.0; maximal alpha-amylase synthesis, on the other hand, was observed in the medium buffered at pH 6.0. The optimal pH for alpha-amylase and glucoamylase activity was in the range of 4.5-7.2 and 4.2-5.5, respectively. Temperatures allowing maximal activity were 45 degrees C for alpha-amylase and 45-52 degrees C for glucoamylase; a rapid decline of both activities was observed just above these temperatures.

Glucan 1,4-alpha-Glucosidase↗
PubMed1986

Activation of a cryptic TACTAAC box in the Saccharomyces cerevisiae actin intron.

We constructed a translational fusion between the Saccharomyces cerevisiae actin gene and the Escherichia coli beta-galactosidase structural gene such that expression of beta-galactosidase activity required accurate splicing of the actin intron. Using this chimeric gene, we generated a series of internal deletions which removed the TACTAAC box or, in addition, TACTAAC-like sequences within the intron. Analysis of the fusion transcripts produced in these deletions allowed us to conclude that the TACTAAC-like sequence TACTAAG can substitute, albeit inefficiently, for the authentic TACTAAC box in the splicing process. These results indicate that the yeast splicing machinery can utilize a cryptic TACTAAC box, but there are requirements for primary sequence and proper position.

Actins↗