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Biomedical subjects

G Guglielmi

Publications and source records attributed to G Guglielmi.

At least 109 records · Page 6Linked to original sources
PubMed1991

Electrothrombosis of saccular aneurysms via endovascular approach. Part 2: Preliminary clinical experience.

Fifteen patients with high-risk intracranial saccular aneurysms were treated using electrolytically detachable coils introduced via an endovascular approach. The patients ranged in age from 21 to 69 years. The most frequent clinical presentation was subarachnoid hemorrhage (eight cases). Considerable thrombosis of the aneurysm (70% to 100%) was achieved in all 15 patients, and preservation of the parent artery was obtained in 14. Although temporary neurological deterioration due to the technique was recorded in one patient, no permanent neurological deficit was observed in this series and there were no deaths. It is believed that this new technology is a viable alternative in the management of patients with high-risk intracranial saccular aneurysms. It may also play an important role in the occlusion of aneurysms in the acute phase of subarachnoid hemorrhage.

Adult↗
PubMed1990

Structure and mutation of a gene encoding a Mr 33,000 phycocyanin-associated linker polypeptide.

The gene encoding a phycocyanin-associated linker polypeptide of Mr 33,000 from the cyanobacterium Synechococcus sp. PCC 7002 was found to be located adjacent and 3' to the genes encoding the alpha and beta subunits of phycocyanin. The identity of this gene, designated cpcC, was proven by matching the amino-terminal sequence of the authentic polypeptide with that predicted by the nucleotide sequence. A cpcC mutant strain of this cyanobacterium was constructed. The effect of the mutation was to prevent assembly of half the total phycocyanin into phycobilisomes. By electron microscopy, phycobilisomes from this mutant were shown to contain rod substructures composed of a single disc of hexameric phycocyanin, as opposed to two discs in the wild type. It was concluded that the Mr 33,000 linker polypeptide is required for attachment of the core-distal phycocyanin hexamer to the core-proximal one. Using absorption spectra of the wild type, CpcC-, and phycocyanin-less phycobilisomes, the in situ absorbances expected for specific phycocyanin-linker complexes were calculated. These data confirm earlier findings on isolated complexes regarding the influence of linkers on the spectroscopic properties of phycocyanin.

Amino Acid Sequence↗
PubMed1990

Structural and compositional analyses of the phycobilisomes of Synechococcus sp. PCC 7002. Analyses of the wild-type strain and a phycocyanin-less mutant constructed by interposon mutagenesis.

The phycobilisomes and phycobiliproteins of Synechococcus sp. PCC 7002 wild-type strain PR6000 have been isolated and characterized. The hemidiscoidal phycobilisomes of strain PR6000 are composed of eleven different polypeptides: phycocyanin alpha and beta subunits; allophycocyanin alpha and beta subunits; alpha subunit of allophycocyanin B; the allophycocyanin beta-subunit-like polypeptide of Mr 18,000; the linker phycobiliprotein of Mr 99,000; and non-chromophore-carrying linker polypeptides of Mr 33,000, 29,000, 9000, and 8000. Several of these polypeptides were purified to homogeneity and their amino acid compositions and amino-terminal amino acid sequences were determined. Analyses of the phycobiliproteins of Synechococcus sp. PCC 7002 were greatly facilitated by comparative studies performed with a mutant strain, PR6008, constructed to be devoid of the phycocyanin alpha and beta subunits by recombinant DNA techniques and transformation of strain PR6000. The absence of phycocyanin did not greatly affect the allophycocyanin content of the mutant strain but caused the doubling time to increase 2-7-fold depending upon the light intensity at which the cells were grown. Although intact phycobilisome cores could not be isolated from this mutant, it is probable that functionally intact cores do exist in vivo.

Amino Acid Sequence↗
PubMed1990

Regression of an internal carotid artery pseudoaneurysm after therapeutic embolization of a post-traumatic carotid-cavernous fistula secondary to gunshot injury.

A case is reported of a 53-year-old woman who was hit by a bullet which penetrated the skull base and caused a left carotid-cavernous fistula of the direct type and a pseudoaneurysmal dilation of the high cervical portion of the left internal carotid artery. The fistula was successfully embolized by positioning a balloon into the fistula itself by means of the Debrun technique: unexpectedly the size of the pseudoaneurysm decreased after the embolization; the possible explanations for this event are discussed.

Arteriovenous Fistula↗
PubMed1990

Persistent primitive trigeminal artery-cavernous sinus fistulas: report of two cases.

Two cases of persistent primitive trigeminal artery-cavernous sinus fistulas are presented. In one case, the fistula was treated by using a two-balloon tandem technique. This method was accomplished by introducing, inflating, and detaching a silicone balloon into the trigeminal artery, thus preserving the carotid and basilar blood flow. An unusual case of a similar fistula with only contralateral exophthalmos is also reported. The relationship between this type of fistula and the presence of aneurysms on the persistent primitive trigeminal artery and the relationship with traumatic events are discussed.

Adult↗
PubMed1990

[Preliminary experience of the study of the hand using digital radiology with photo-excitable phosphors and direct magnification. Comparison with the traditional high resolution technique].

Photostimulable phosphor computed radiography (CR) is a new technique. The authors applied direct magnification CR to hand study (IP matrix: 1770 x 2370), and compared the results with conventional radiography ones (high MTF industrial type film, without screens, 5 x optic enlargement reading). In both cases, a mammographic unit was employed for acquiring the images. Thirty patients affected with renal osteodystrophy, psoriatic arthropathy or rheumatoid arthritis, and 20 normal subjects were examined. Digital images were processed by a particular sensitometry curve and spatial filtering with unlinear unsharp masking: we obtained good visualization of small lesions (subperiosteal resorption, cortical bone tunnelling, minute periosteal necrosis), not inferior to that obtained with conventional techniques. CR has further advantages, such as low economic and biological cost, wide exposure and recording range, image processing, easy archiving and networking.

Arthritis, Psoriatic↗
PubMed1990

[High-resolution rapid multiplanar reconstructions in the CT study of the spine. Our experience].

The authors describe the utility of fast and high-resolution multiplanar CT reconstructions in the study of the rachis. Their experience is reported with an up-to-date software with 2 different representation modalities (CMR 01B). A "package" of contiguous axial images is obtained in a standard way; the images are then reformatted by computer to obtain (in just a few seconds) high-resolution reconstructed images in different planes (coronal, sagittal, and oblique). In the authors' opinion the method, in spite of some limitations, yields in most cases additional information which is not provided by conventional CT. Reconstructed images are most useful in the study of complex anatomical structures (such as vertebral metameres) along their anatomical planes.

Humans↗
PubMed1989

Occurrence and distribution of gas vesicle genes among cyanobacteria.

Gas vesicles (GV) are specialized cell inclusions providing many aquatic procaryotes with buoyancy. In the cyanobacterium Calothrix sp. strain PCC 7601, at least four genes are involved in GV formation. One of those, gvpA1, encodes the major structural GV protein (70 amino acids) and belongs to a multigene family (gvpA1, gvpA2, gvpD). The fourth gene, gvpC, encodes a 162-amino-acid protein, the function of which is still unclear. We used the Calothrix gvpA1 and gvpC genes as probes to perform Southern hybridization experiments with DNA extracted from various cyanobacterial strains. The gvpA gene was found in all the strains that synthesize GV, indicating that its product is an obligatory component of GV. Furthermore, it was found to occur as multiple copies in most of the strains tested. The gvpC gene was only detected in some strains able to synthesize a large amount of GV within a short period. This suggests that the gvpC gene product is a dispensable protein for GV formation and is involved in the efficiency of the assembly process. Based on the occurrence of the gvp genes and on DNA-DNA hybridization patterns, genus assignments are discussed.

Bacterial Proteins↗
PubMed1988

Cystic meningiomas.

Twenty-two cases of unusual intracranial meningioma associated with a cyst are reported and 144 published cases reviewed. The complex mechanisms leading to the formation of the cyst within the meningioma are analyzed on the basis of the surgical and histopathological evidence. The neuroradiological features (Computed Tomography and Angiography) which supply a correct preoperative diagnosis are discussed. It is clear from the literature how difficult preoperative diagnosis is, being possible only in 38% of cases with CT scanning and in 13% with angiography. It is necessary to remove not only the solid portion of the meningioma but also the cyst wall in order to prevent a recurrence. This is technically difficult for the type II intratumoural variety of Nauta's classification.

Adolescent↗
PubMed1988

Therapeutic embolization of an ascending pharyngeal artery-internal jugular vein fistula. Case report.

The authors report a case of an arteriovenous fistula between the ascending pharyngeal artery and the internal jugular vein. The importance of an exact diagnosis and some precautions to be taken during therapeutic embolization are emphasized, as well as the need for superselective cannulation of the feeding artery. The problem of differential diagnosis with glomus tumors is discussed, and a brief mention is made of the anatomy of the jugular foramen and embryology of these tumors. Only one similar case treated by embolization with solid particles was found in the literature. To date, embolization using solid particles rather than liquid agents appears to be the best treatment of fistulas of this type.

Angiography↗
PubMed1987

A developmentally regulated gvpABC operon is involved in the formation of gas vesicles in the cyanobacterium Calothrix 7601.

In the filamentous cyanobacterium Calothrix PCC7601, gas-vesicle (GV) formation is restricted to specialized filaments, called hormogonia. The differentiation of these cells is controlled by environmental factors, such as light intensity and/or wavelength. The structural gene (gvpA) encoding a GV protein in this cyanobacterium has been previously cloned and sequenced. Two other genes, gvpB and gvpC have been found in the sequence downstream from gvpA. The gvpB gene corresponds to a second copy of gvpA, encoding an identical protein. Unlike the GV protein, the product of the gvpC gene is predominantly hydrophilic, as deduced from nucleotide sequence. Interestingly, the internal part of the gvpC gene is composed of four contiguous repeats, each containing 99 bp, forming highly homologous repeats in the deduced amino acid sequence. Another kind of periodicity has been detected inside the 99-bp repeats, suggesting that the gvpC gene might have evolved by amplification of a 33-bp-long primordial building block. The function of this gene remains to be elucidated. Finally, we have shown that the three genes, gvpA, gvpB, and gvpC, are organized in an operon that is exclusively expressed during GV formation in hormogonia.

Amino Acid Sequence↗
PubMed1987

Functional expression of plastid allophycocyanin genes in a cyanobacterium.

In Cyanophora paradoxa, the allophycocyanin apoprotein subunits, alpha and beta, are encoded in the cyanelle (plastid) genome. These genes were transferred to the cyanobacterium Synechococcus sp. PCC 7002 on a plasmid replicon. Phycobilisomes isolated from transformed cyanobacteria were found to contain C. paradoxa allophycocyanin subunits. Thus, these plastid genes are expressed in the cyanobacterium as polypeptides which become linked to a chromophore and are incorporated into the light-harvesting apparatus.

Cloning, Molecular↗
PubMed1986

Green light induces transcription of the phycoerythrin operon in the cyanobacterium Calothrix 7601.

Phycobilisomes, the major light-harvesting complexes of cyanobacteria are multimolecular structures made up of chromophoric proteins called phycobiliproteins and non chromophoric linker polypeptides. We report here the isolation and nucleotide sequence of the genes, cpeA and cpeB, which in Calothrix PCC 7601 encode the alpha and beta subunits of phycoerythrin, one of the major phycobiliproteins. In Calothrix PCC 7601, modulation of the polypeptide composition of the phycobilisomes occurs in response to changes of the light wavelength, a phenomenon known as complementary chromatic adaptation. Under green illumination, cells synthesize phycoerythrin and its two specifically associated linker polypeptides (LR35 and LR36), while under red illumination none of these proteins are detected. Using specific probes, a single transcript (1450 nucleotide long) corresponding to the cpe genes was detected but only in green-light-grown cells, establishing the occurrence of transcriptional regulation for the expression of this operon in response to light wavelength changes. The size of this transcript excludes the possibility that the phycoerythrin-associated LR35 and LR36 could be cotranscribed with the cpeA and cpeB genes.

Amino Acid Sequence↗
PubMed1986

[Hyperlipidemia findings in workers in an oil refinery].

During a cross sectional epidemiologic study the cholesterol and triglyceride plasmatic levels were measured in 207 workers employed in an oil refinery. Our results show high levels both for cholesterol and triglyceride. Emphasis has been laid on the serious dietary and hygienic problems for these workers. The finding of hyperlipidemia as well as obesity and over-weight do not seem to be related to exposure to any occupational chemical hazard.

Adult↗
PubMed1985

Chromatic adaptation in a mutant of Fremyella diplosiphon incapable of phycoerythrin synthesis.

A mutant of the chromatically adapting cyanobacterium Fremyella diplosiphon, incapable of phycoerythrin synthesis but responding to wavelength modulation of its biliprotein content, was isolated. The biliprotein composition of the mutant and of the wild type were identical after growth in red light, but green light induced, in the mutant, the synthesis of a biliviolin-type chromophore bound to some of the alpha subunits of its phycocyanin. Implications of the results on the regulation and possible pathways of biliprotein biosynthesis are discussed.

Adaptation, Physiological↗