Biomedical subjects
F Giorgi
Publications and source records attributed to F Giorgi.
[Computerized data on retinal vascular disorders (occlusion of the branches of the retinal veins and drepanocytosis)].
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[Smith-Lemli-Opitz syndrome. Case report and differential diagnosis].
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Variations in the vitellogenin titre during the reproductive cycle of Rana esculenta L.
1. Vitellogenin titre has been measured by rocket immunoelectrophoresis in specimens of Rana esculenta L. caught at three different locations in southern Italy. 2. Variations in the serum level of vitellogenin are temporally related to ovarian growth during the reproductive cycle. 3. With the exception of the FL population, vitellogenin titre is low at spawning time but increases prior to ovarian recovery. 4. It eventually levels off, or undergoes a slight decline during winter, when the ovary is in a static phase. 5. The evidence presented in this study is consonant with the experimental model on hormonal control of vitellogenesis. 6. The vitellogenin patterns observed in the populations examined in this study are interpreted as due to different environmental conditions even though the hybridogenetic nature of Rana esculenta has also to be taken into account.
Vitellogenesis in the stick insect Carausius morosus I. Specific protein synthesis during ovarian development.
Vitellogenesis in the stick insect Carausius morosus (Br.) has been studied with the goal of identifying vitellogenin in various tissues. Following exposure to in vivo to radioactive amino acids, oocytes in the medium size range are labelled with a minimum delay of 6 h after the time of injection. Incorporation of radioactivity under these conditions is shown to depend upon accumulation of proteins rather than on a differential rate of protein synthesis in succeeding stages of oogenesis. By immunochemical analyses, it is shown that at least two antigens are common to both haemolymph and ovary and that one of these is also present in the fat body. Both antigens are labelled during exposure to radioactive amino acids. When analysed by the SDS polyacrylamide gel electrophoresis, extracts from both haemolymph and ovary appear to share a number of protein fractions which range in molecular weight from 40 000 to 200 000 Daltons. The labelling pattern exhibited by these fractions is clearly indicative of a protein transfer from the fat body to the oocyte. Fat body cultured in vivo for up to 4 h releases a major macromolecular complex in the external medium. The latter has been identified as vitellogenin by both immuno-precipitation assay and SDS polyacrylamide gel electrophoresis. The protein which is synthesized and secreted under these conditions results from the processing of a protein complex of higher molecular weight.
Immunochemical identification of vitellogenin in the serum of the newt Triturus cristatus.
The hematic yold precursor--vitellogenin--has been identified immunochemically in the serum of estrogenized females of the nest Triturus cristatus by employing an antiserum prepared against yold proteins.
In vitro induced pinocytotic activity by a juvenile hormone analogue in oocytes of Drosophila melanogaster.
Pinocytotic activity has been analyzed in Drosophila oocytes following either in vivo or in vitro exposure to horseradish peroxidase. The enzyme tracer gains access to the yolk spheres only when supplied to the oocyte in vivo. In oocytes cultured in vitro, peroxidase remains restricted to the residual coated vesicles and to the tubular profiles formed in excess in the cortical ooplasm. In an attempt to induce peroxidase uptake by oocytes cultured in vitro, various incubations were tested. Among these, hemolymph from both sexes is capable of promoting peroxidase uptake up to a level comparable to that detectable in vivo. On the other hand, fat body extracts fail to promote such cellular activity. Finally, the juvenile hormone analogue ZR-515 is shown to be the only factor required to promote pinocytotic activity under the experimental conditions tested. The observations are interpreted to indicate that vitellogenin has no inductive role on pinocytosis but simply acts by adhering to the forming coated vesicles which in turn are produced by the oolemma in response to the action of juvenile hormone.
Intercellular bridges in ovarian follicle cells of Drosophila melanogaster.
Intercellular bridges have been detected in ovarian follicle cells of Drosophila melanogaster. These bridges occur widely between follicle cells of previtellogenic chambers, while, in vitellogenic chambers, they become restricted to the columnar follicle cells. Usually, only one bridge is detectable between adjacent follicle cells, but a single cell may form two cytoplasmic continuities. The fine structure of the intercellular bridges is similar to that previously described in the development of Drosophila. The bridge wall consists of two layers of which the more external is more electron dense and thinner than the inner one. The role played by the intercellular bridges in the determination of asynchronous differentiation of the linked follicle cells is discussed in relation ot the known behaviour of these cells in the secretion of the egg covering precursors.
An EM autoradiographic study on ovarian follicle cells of Drosophila melanogaster with special reference to the formation of egg coverings.
Ovarian follicle cells of Drosophila melanogaster have been studied by ultrastructural and autoradiographic analyses. During their migration through the germarium, follicle cells undergo several structural changes and, of these, the most conspicuous one occurs at the level of the nucleolus. By the time the first ovarian chamber is formed, follicle cells have formed a layer of uniform thickness all around a cluster or nurse cells and the oocyte. Following the initiation of vitellogenesis, the follicle cells overlaying the oocyte become columnar while those over the nurse cells become very thin. During stages 9-10, the columnar follicle cells are involved in the formation of the vitelline membrane, while from stages 11 to 13 these cells produce the endochorion. An EM autoradiographic analysis has shown that the rate of 3H-uridine incorporation in follicle cells nuclei is low in previtellogenic chambers, while it becomes very high in nuclei of stage 9-10 chambers. After short exposure to uridine, silver grains are located predominantly over nucleoli. Evidence from incorporation studies with 3H-lysine indicates that the columnar follicle cells and the region of the various egg coverings are highly labelled within an hour of incubation in the tracer. The observations confirm that columnar follicle cells are the only cells in the chamber involved in the formation of materials which make up the egg coverings.
Recent findings on oogenesis of Drosophila melanogaster. I. Ultrastructural observations on the developing ooplasm.
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Recent findings on oogenesis of Drosophila melanogaster. II. Further evidence on the origin of yolk platelets.
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Recent findings in oogenesis of Drosophila melanogaster. III. Lysosomes and yolk platelets.
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Cytochemistry of late ovarian chambers of Drosophila melanogaster.
Late ovarian chambers of Drosophila melanogaster have been examined by ultrastructural cytochemistry in an attempt to characterize some of the transformations which precede the completion of oogenesis. From stage 11 onward peroxidase activity is present in the endoplasmic reticulum of both nurse cells and oocyte, as well as in the egg-covering precursors of the columnar follicle cells. Catalase activity is restricted to the very last stages of oogenesis (stage 13-14) and appears to be located in membrane-bound organelles of the ooplasm which are continuous with the endoplasmic reticulum. Because of the presence of catalase as well as by their structural appearance, these organelles are to be identified as microperoxisomes. Catalase activity becomes cytochemically detectable in the ooplasm somehow in coincidence with the formation of glycogen. Furthermore, glycogen is first formed in intimate association with alpha-1 yolk platelets. On the basis of these findings it is suggested that glycogen synthesis occurs by a process of gluconeogenesis.
Osmium zinc iodide staining of Golgi elements in oocytes of Triturus cristatus.
Developing oocytes of the newt Triturus cristatus were studied in order to clarify the role played by the Golgi apparatus in the formation of yolk. The cytochemical method used for this purpose was that of Maillet (1968) which employs an Osmium Zinc Iodide (OZI) complex. Previtellogenic oocytes reveal a pattern of OZI staining only after hormonal (HCG) stimulation, following which both the Golgi apparatus and the multivesicular bodies are stained. Vitellogenic oocytes taken from non-hormonally stimulated females reveal OZI deposits in a number of vesicles peripheral to the Golgi apparatus as well as within the superficial layer of the forming yolk platelets. Following hormone stimulation, many of the Golgi apparatus located in the central ooplasm of vitellogenic oocytes have all their cisternae blackened by the OZI deposits; other apparatuses,more peripherally located, remain essentially unchanged in their staining pattern. Further, a large number of OZI stained vesicles becomes visible in the vicinity of the Golgi apparatus and within the superficial layer of the forming yolk platelets. The present findings are interpreted as indicating the occurrence of fusion between Golgi derived vesicles and forming yolk platelets. It is also suggested that the vesicles in question function as carriers of Golgi produced enzymes which are presumably required to accomplish the final elaboration of the yolk material.
Cell death in ovarian chambers of Drosophila melanogaster.
An ultrastructural analysis has been made of certain ovarian chambers undergoing abnormal development. The earliest morphological change in these chambers consists of the alteration of the nuclear material which is then followed by engulfment of portions of the nurse cell cytoplasm, including the nuclear fragments, into the overlying follicle cells. The continuation of this process leads to the progressive disappearance of nurse cells with the concomitant formation of huge dense vacuoles in the follicle layer. The morphological features described in the present investigation are similar to those found in other tissues and interpreted as leading to cell death. It is suggested that certain ovarian chambers undergo cell death as a result of the incapability of furthering their development. The role played by cell death in oogenesis is also discussed on the basis of the current literature.
Ultrastructural observations on the degenerating nurse cells of late ovarian chambers of Drosophila melanogaster.
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Sucralfate prophylaxis of fluorouracil-induced stomatitis.
AIMS AND BACKGROUND: Various attempts have been made to prevent 5-fluorouracil-induced stomatitis, with unsatisfactory results. Sucralfate is an aluminum hydroxide complex of sulfated sucrose commonly used in the treatment of gastroduodenal ulcers. We used the compound in a phase II study to reduce and minimize the stomatotoxicity of 5-fluorouracil chemotherapy administered in a multiple-day schedule. METHODS: Fifty-two patients entered the study, and 129 cycles of chemotherapy were evaluated. Seven patients refused sucralfate rinses for taste intolerance. RESULTS: A low level of stomatotoxicity was recorded: grade 2 stomatitis was observed after 14 cycles (10.8%) and grade 3 after 3 cycles (2.3%). CONCLUSIONS: Sucralfate administration could have a role in the prevention of 5-fluorouracil-induced stomatitis.
[Thrombophlebitis of the cavernous sinus and inappropriate ADH secretion syndrome].
The septic thrombosis of the cavernous sinus is a rare and serious disease which still occurs occasionally. The physician should be aware of this fact when treating infections of the nasal orbital areas. A case is presented in whom the septic thrombosis of the cavernous sinus is associated with the syndrome of inappropriate secretion of antidiuretic hormone.