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Biomedical subjects

F Guzzo

Publications and source records attributed to F Guzzo.

13 recordsLinked to original sources
PubMed2002

Outbreak of African tick-bite fever in six Italian tourists returning from South Africa.

In May 1999, a cluster of cases of African tick-bite fever was detected in six Italian tourists who had returned from South Africa. All of the patients had moderate fever and cutaneous eschars. Regional lymphangitis was observed in three of the patients and skin rash in two. By comparing the number of eschars with the number of detectable bite sites it was suggested that at least two-thirds of the biting vectors were capable of transmitting Rickettsia africae. The clinical course of disease was mild in all cases, and all but one of the patients recovered spontaneously before antibiotic treatment was initiated. The diagnosis of African tick-bite fever was confirmed serologically using both microimmunofluorescence and Western blot tests.

Animals↗
PubMed2001

Isolation and characterization of Borrelia burgdorferi sensu lato strains in an area of Italy where Lyme borreliosis is endemic.

Between 1993 and 1998, we isolated Borrelia burgdorferi sensu lato from 55 of the 119 patients with clinically diagnosed Lyme borreliosis who were admitted to "San Martino" Hospital in Belluno, Veneto, an Adriatic region in northeastern Italy where Lyme borreliosis is endemic. Upon hospitalization, all patients presented erythema migrans. Isolates were typed using ribosomal DNA PCR-restriction fragment length polymorphism (RFLP) analysis of the rrfA-rrlB intergenic spacer. Of the 41 isolates typed, 37 belonged to Borrelia afzelii, 2 to Borrelia garinii, and 2 to B. burgdorferi sensu stricto. Pulsed-field gel electrophoresis, performed on 21 strains (13 new isolates and 8 controls), revealed different RFLP patterns within the B. garinii and B. afzelii strains; among the five B. garinii strains and the 12 B. afzelii strains, three or two different RFLP patterns were identified, according to the restriction enzyme used. The protein patterns of the new isolates confirmed their genotypic classification and revealed the level of expression of some immunodominant proteins like OspA and other characteristic Osps. These findings constitute the first report of such a high recovery rate of B. burgdorferi from patients in a very restricted area in Italy; they also indicate the predominance of the genospecies B. afzelii in the study area and the heterogeneity of the circulating strains.

Adult↗
PubMed2000

KDC1, a novel carrot root hair K+ channel. Cloning, characterization, and expression in mammalian cells.

Potassium is an essential nutrient which plays an important role in many aspects of plant growth and development. Plants have developed a number of highly specific mechanisms to take up potassium from the soil; these include the expression of K(+) transporters and potassium channels in root cells. Despite the fact that root epidermal and hair cells are in direct contact with the soil, the role of these tissues in K(+) uptake is not well understood. Here we report the molecular cloning and functional characterization of a novel potassium channel KDC1 which forms part of a new subfamily of plant K(in) channels. Kdc1 was isolated from carrot root RNA and in situ hybridization experiments show Kdc1 to be highly expressed in root hair cells. Expressing the KDC1 protein in Chinese hamster ovary cells identified it as a voltage and pH-dependent inwardly rectifying potassium channel. An electrophysiological analysis of carrot root hair protoplasts confirmed the biophysical properties of the Kdc1 gene product (KDC1) in the heterologous expression system. KDC1 thus represents a major K(+) uptake channel in carrot root hair cells.

Amino Acid Sequence↗
PubMed2000

A new FISH protocol with increased sensitivity for physical mapping with short probes in plants.

Fluorescence in situ hybridization (FISH) is a well-established technique used for the detection of specific DNA regions, that has been applied to interphase nuclei, pachytene and metaphase chromosomes as well as to extended DNA fibres. This technique allows the physical mapping of specific DNA sequences both on individual chromosomes and extended fibres. A new FISH protocol is described here that enhances the sensitivity of the method. Probes for small unique DNA sequences of less than 2 kb give high signal-to-noise ratio with this method, and can be visualized easily by means of conventional fluorescence microscopy.

Asparagus Plant↗
PubMed1998

Expression pattern of the carrot EP3 endochitinase genes in suspension cultures and in developing seeds

Carrot (Daucus carota) extracellular protein 3 (EP3) class IV endochitinases were previously identified based on their ability to rescue somatic embryos of the temperature-sensitive cell line ts11. Whole-mount in situ hybridization revealed that a subset of the morphologically distinguishable cell types in embryogenic and nonembryogenic suspension cultures, including ts11, express EP3 genes. No expression was found in somatic embryos. In carrot plants EP3 genes are expressed in the inner integumentary cells of young fruits and in a specific subset of cells located in the middle of the endosperm of mature seeds. No expression was found in zygotic embryos. These results support the hypothesis that the EP3 endochitinase has a "nursing" function during zygotic embryogenesis and that this function can be mimicked by suspension cells during somatic embryogenesis.

Journal Article↗
PubMed1997

The secretory nature of the lesion of carrot cell variant ts11, rescuable by endochitinase.

The carrot cell variant ts11 is unable to form somatic embryos at the non-permissive temperature of 32 degrees C, but the block can be overcome by the addition of a 32-kDa acidic endochitinase to the medium. In this work we conducted a cyto-histological analysis of the blocked embryo forms. The morphology of the endomembrane system is altered; in particular, the ER is dilated and may show electron-dense precipitates and continuity with the plasma membrane. These morphological alterations do not occur in the presence of externally-added endochitinase. We also noticed modifications of the culture medium that are probably related to the morphological observations: the total amount of secreted proteins is reduced and pulse-chase experiments revealed that, compared with wild-type cells, the secretion of major polypeptides is reduced while new minor polypeptides are secreted. Western blot analysis revealed the presence of the binding protein BiP, a resident of the ER and of glutamine synthase, a cytosolic protein, in the medium of ts11 but not wild-type cells. These results indicate that ts11 is altered in the secretory pathway but do not clarify the role of endochitinase.

Cells, Cultured↗
PubMed1997

A leucine-rich repeat containing receptor-like kinase marks somatic plant cells competent to form embryos.

The first somatic single cells of carrot hypocotyl explants having the competence to form embryos in the presence of 2,4-dichlorophenoxyacetic acid (2,4-D) were identified using semi-automatic cell tracking. These competent cells are present as a small subpopulation of enlarged and vacuolated cells derived from cytoplasm-rich and rapidly proliferating non-embryogenic cells that originate from the provascular elements of the hypocotyl. A search for marker genes to monitor the transition of somatic into competent and embryogenic cells in established suspension cell cultures resulted in the identification of a gene transiently expressed in a small subpopulation of the same enlarged single cells that are formed during the initiation of the embryogenic cultures from hypocotyl explants. The predicted amino acid sequence and in vitro kinase assays show that this gene encodes a leucine-rich repeat containing receptor-like kinase protein, designated Somatic Embryogenesis Receptor-like Kinase (SERK). Somatic embryos formed from cells expressing a SERK promoter-luciferase reporter gene. During somatic embryogenesis, SERK expression ceased after the globular stage. In plants, SERK mRNA could only be detected transiently in the zygotic embryo up to the early globular stage but not in unpollinated flowers nor in any other plant tissue. These results suggest that somatic cells competent to form embryos and early globular somatic embryos share a highly specific signal transduction chain with the zygotic embryo from shortly after fertilization to the early globular embryo.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1993

Antihyperglycemic activity of novel naphthalenyl 3H-1,2,3,5-oxathiadiazole 2-oxides.

A series of naphthalenyl 3H-1,2,3,5-oxathiadiazole 2-oxides was prepared and tested for antihyperglycemic activity in the db/db mouse, a model for type 2 (non-insulin dependent) diabetes mellitus. Substitution at the 1-, 5-, or 8-positions of the naphthalene ring with a halogen was found to be beneficial to antihyperglycemic activity. 4-[(5-Chloronaphthalen-2-yl)methyl]-3H-1,2,3,5-oxathiadiazole++ + 2-oxide (45), one of the most potent compounds in this series, was selected for further pharmacological evaluation.

Animals↗
PubMed1993

Purification of calreticulin-like protein(s) from spinach leaves.

In a search for the plant equivalent of calsequestrin or calreticulin, the high capacity, low affinity Ca2+ binding proteins of muscle and non-muscle cells thought to play important roles in Ca2+ storage, we purified two Ca(2+)-binding proteins from spinach leaves. The proteins had apparent molecular weights of 55 and 53 kDa. On Western blot, they did not react either with anti-rabbit skeletal muscle, anti-dog cardiac muscle calsequestrin or anti-rabbit or anti-rat liver calreticulin antibodies, indicating that they were antigenically distinct. Periodic acid Schiff staining (PAS) revealed that the larger protein was glycosylated while the 53 kDa one was PAS-negative. When the proteins were subjected to NH2-terminus amino acid sequencing, the 55 and 53 kDa proteins turned out to be identical, thus probably representing different isoforms of the same protein. Comparison with published amino acid sequences of calreticulin reveals regions of similarity indicating that the plant Ca(2+)-binding proteins probably belong to the calreticulin family.

Amino Acid Sequence↗
PubMed1992

Antihyperglycemic activity of novel substituted 3H-1,2,3,5-oxathiadiazole 2-oxides.

A series of substituted 3H-1,2,3,5-oxathiadiazole-2-oxides (6) was prepared and tested for antihyperglycemic activity in the db/db mouse, a model for type 2 (non-insulin dependent) diabetes mellitus. The oxathiadiazoles 6 were synthesized by a two-step sequence: treatment of a substituted acetonitrile (4) with hydroxylamine to give the corresponding amidoxime (5) and cyclization with thionyl chloride to yield 6. In terms of potency, the 2-naphthalenylmethyl group (as in compound 3) was found to be the optimal substituent in this series. Compound 3 was approximately 5 times more potent than ciglitazone (1).

Animals↗
PubMed1990

(Pyrimidinyloxy)acetic acids and pyrimidineacetic acids as a novel class of aldose reductase inhibitors.

Pyrimidineacetic acids and (pyrimidinyloxy)acetic acids were synthesized by alkylation, with methyl bromoacetate or tert-butyl bromoacetate as alkylating agents. Alkylation reaction at the nitrogen or oxygen atom for different substrates was found to be solvent dependent. N-Alkylation was favored in ethereal solvent, e.g., tetrahydrofuran and dimethoxyethane, whereas O-alkylation was predominant in dimethylformamide. These compounds were tested in vitro to determine their ability to inhibit bovine lens aldose reductase. Selected compounds were assayed in vivo, in a 4-day galactose-fed rat model. The decrease in galactitol from the control was determined in lens, nerve, and diaphragm. Several of the 6-oxopyrimidine-1-acetic acids and (pyrimidinyl-4-oxy)acetic acids were found to be potent inhibitors of bovine lens aldose reductase. A study was also undertaken to determine in vitro the transport behavior of selected compounds in the isolated rat sciatic nerve. A discussion of the structure-activity relationship of this class of compounds with reference to their intrinsic biochemical activity is reported. It is concluded, in general, that ability of a compound to penetrate the tissue membrane plays an important role in the genesis of in vivo lens aldose reductase (LAR) inhibitory activity.

Acetates↗