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Biomedical subjects

F Cortese

Publications and source records attributed to F Cortese.

54 records · Page 3Linked to original sources
PubMed1978

Cytochalasin-stimulated steroidogenesis from high density lipoproteins.

The cytochalasins stimulate steroid secretion of Y-1 adrenal tumor cells two-to threefold. The order of potencies is cytochalasin E is greater than D is greater than B, but the maximum response is the the same and always less than with ACTH. Like that with ACTH, the stimulation has a rapid onset, is easily reversible, is inhibited by cucloheximide and aminoglutethimide, and occurs at a stage before pregnenolone. Although the cytochalasin, like ACTH, produce cell rounding, it is shown that this morphological change is not necessarily coupled to steridogenesis. Unlike ACTH, cytochalasin B does not measurably increase cellular levels of cAMP at concentrations that lead to maximal steroidogenesis. The cytochalasin B-induced stimulation of steroidogenesis, unlike the short-term ACTH effect, fails to occur in the absence of serum. This lack of response can be corrected by even low concentrations of human high density lipoproteins (HDL) but not by low density lipoproteins (LDL). We, therefore, propose that cytochalasin B enhances the availability of cholesterol bound to HDL for steroidogenesis by Y-1 adrenal cells.

20-alpha-Dihydroprogesterone↗
PubMed1977

Podophyllotoxin as a probe for the colchicine binding site of tubulin.

The binding of [3H]podophyllotoxin to tubulin, measured by a DEAE-cellulose filter paper method, occurs with an affinity constant of 1.8 X 10(6) M-1 (37 degrees at pH 6.7). Like colchicine, approximately 0.8 mol of podophyllotixin are bound per mol of tubulin dimer, and the reaction is entropy-driven (43 cal deg-1 mol-1). At 37 degrees the association rate constant for podophyllotoxin binding is 3.8 X 10(6) M-1 h-1, approximtaely 10 times higher than for colchicine; this is reflected in the activation energies for binding which are 14.7 kcal/mol for podophyllotoxin and 20.3 kcal/mol for colchicine. The dissociation rate constant for the tubulin-podophyllotoxin complex is 1.9 h-1, and the affinity constant calculated from the ratio of the rates is close to that obtained by equilibrium measurements. Podophyllotxin and colchicine are mutually competitive inhibitors. This can be ascribed to the fact that both compounds have a trimethoxyphenyl ring and analogues of either compound with bulky substituents in their trimethoxyphenyl moiety are unable to inhibit the the binding of either of the two ligands. Tropolone, which inhibits colchicine binding competitively, has no effect on the podophyllotoxin/tubulin reaction. Conversely, podophyllotoxin does not influence tropolone binding. Moreover, the tropolone binding site of tubulin does not show the temperature and pH lability of the colchicine and podophyllotoxin domains, hence this lability can be ascribed to the trimethoxyphenyl binding region of tubulin. Since podophyllotoxin analogues with a modified B ring do not bind, it is concluded that both podophyllotoxin and colchicine each have at least two points of attachment to tubulin and that they share one of them, the binding region of the trimethoxyphenyl moiety.

Animals↗
PubMed1976

Isopycnic centrifugation of thyroid iodoproteins: selectivity of endocytosis.

Isopycnic centrifugation in RbCl was shown to be an effective method both for evaluating the iodine content of thyroglobulin labelled in vivo and for the fractionation of thyroglobulin molecules as a function of their iodine content. Iodination and degradation of thyroid iodoproteins were studied by this method and by zonal centrifugation in sucrose density gradients. Based on these methods it was shown that iodination in vivo is a selective process, 19-S and poorly iodinated thyroglobulin having a higher reactivity toward iodine than 27-S and iodine-rich thyroglobulin. The disappearance of iodoproteins from the thyroid was evaluated by equilibrium, labelling the iodoproteins, blocking iodine incorporation with thiourea derivatives and observing (by sucrose gradient and by RbCl isopycnic centrifugation) at different times the properties of the remaining molecules. Among molecules of different size (19-S and 27-S) and among molecules of the same size (19 S) but different iodine content it was shown that reabsorption from the thyroid gland occurred at the same rate. It was concluded, therefore, that the degradative pathway is essentially a random, non-selective process. Newly iodinated (pulse-labelled) iodoproteins were degraded faster than preexisting molecules. Among the pool of those newly iodinated thyroid proteins, 27-S molecules were reabsorbed faster than 19-S molecules and iodine-rich thyroglobulin molecules were reabsorbed faster than the iodine-poor ones. Since iodination in vivo occurs as repeated pulses of iodine incorporation, it is suggested that this latter phenomenon is a regulatory mechanism which minimizes degradation of molecules which are iodine-poor and have a lower hormonal content.

Animals↗
PubMed1975

[Iodoamino acid composition of rat thyroglobulin of varying total iodine concentration and fractions isolated by isopycnic ultracentrifugation].

Iodoaminoacid content (iodothyronines, T3 and T4, and iodotyrosines, MIT and DIT) has been determined in enzymatic hydrolysates of thyroglobulin Tg 19S of different iodine content (0.3-0.9%) isolated from equilibrium labeled rats. Preparative equilibrium centrifugation in RbCl density gradients of pure thyroglobulin was used to obtain protein fractions of largely different iodine content (0.2-1.2% I). Thin layer chromatography of total hydrolysates demonstrated that the distribution of iodoaminoacids depends on the total iodine content of each fraction. It is concluded, in agreement with previous results, that the native structure of Tg is an important factor in the regulation of hormone biosynthesis and that even at low iodination levels of Tg. T3 and T4 are synthesized.

Amino Acids↗
PubMedDate not supplied

Treatment of the sequelae of primary pathology of the hip by correction osteotomy and femoral lengthening using a combined external fixator.

It is not an exceptional event to observe the sequelae of primary pathology of the hip in young patients that, as such, are not of the ideal age for replacement surgery. Moreover, one must not overlook the difficulties involved in replacement surgery for the treatment of inveterate modifications in the normal hip anatomy. Often, among the sequelae of primary pathology of the hip, deformities of the lower limb must also be included, associated or consequent, which also need treatment. For these reasons, the authors, in three selected cases, used a combined external fixator (circular and lateral) by means of which they were at the same time able to correct the axial deformity (with a support osteotomy), and the residual hypometria (with femoral lengthening). Osteotomy plus lengthening, using an external fixator, avoid hypometria of the limb and deformity in valgus of the knee, and allow for results which would otherwise not be obtained with replacement surgery alone.

Adult↗
PubMedDate not supplied

[Treatment of esophageal achalasia].

4 cases of oesophageal achalasia, 2 primary and 2 recurrences following multiple oesophagomyotomy are reported. The superiority of oesophagomyotomy carried out by the left transthoracic route (according to Ellis) in cases of primary achalasia is stressed. On the basis of the literature and reported experience, it is concluded that this approach is also preferable in recurrences when the previous operation was done by the abdominal route and the recurrence occurred within 6 months. In all other cases, particularly in the presence of an achalasic megaoesophagus, partial oesophagogastric resection with interposition of a jejunal loop (Merendino's operation) is the procedure of choice and the satisfactory results of using it are reported.

Adult↗
PubMedDate not supplied

[Magnetic resonance angiography in liver transplant patients. Follow-up of vascular anastomoses].

Twenty liver transplant patients were examined with MRA and color-Doppler US 18 to 40 days after surgery to investigate the onset of vascular complications after surgical liver revascularization. Vascular anastomoses are the most frequent location for such complications as stenoses, occlusions, pseudoaneurysms and vessel ruptures. In liver transplant there are 4 vascular anastomoses, i.e. hepatic artery, portal vein and superior and inferior anastomoses of the inferior vena cava. MRA images were acquired with a superconductive unit operating at 1.5 T, using fast low angle shot (FLASH) 2D sequences on the coronal plane; all images were postprocessed with the MIP algorithm. The presence of a paramagnetic artifact, the "double black spot sign", caused by the suture wire used to make the vascular anastomoses, allowed us to precisely detect the site and the flow pattern alterations at this level. MRA images were studied by two independent observers and vascular anastomosis depiction was rated as "good", "fair" and "poor". The demonstration of portal vein anastomoses was good in the whole series (20/20 patients). The superior anastomosis of the inferior vena cava was clearly depicted in 19 cases and fairly depicted in only 1 patient. The inferior anastomosis of the inferior vena cava was clearly depicted in 19 patients and fairly depicted in 1 case. Hepatic artery anastomoses were far more difficult to demonstrate than the others, considering their caliber and flow pattern, but its depiction was nevertheless good in 12 cases, fair in 6 and poor in only 2 patients. In our series, only one portal vein stenosis was observed, which was clearly depicted on both MRA and US images. In conclusion, MRA is a useful and reliable noninvasive diagnostic tool to study vascular anastomoses in liver transplant patients.

Adolescent↗
PubMedDate not supplied

[Treatment of hemorrhoidal peduncles with diathermy probe].

Diatermy hemorrhoidectomy, without suture of hemorrhoidal pedicles, is a variant of the classical Milligan and Morgan operation. This procedure, if correctly performed, reduces postoperative pain and complications; results are good. Great care is reserved to internal sphincter; it must not be involved in coagulation. Evaluation concerning 100 personal cases are referred.

Diathermy↗
PubMedDate not supplied

[A case of ileal perforation caused by Crohn's disease].

A case of acute perforation of the small bowel in a 32-year-old man with Crohn's disease not previously diagnosed is presented. The patient underwent an emergency bowel resection and anastomosis and was put on 5-ASA for the following 4 years. No clinical or endoscopic recurrences appeared during this period. In order to avoid both functional disorders and recurrences, a surgical treatment based on resection and anastomosis in minor risk cases, i.e. in patients without abscess and/or concurrent steroid therapy, and on resections limited to grossly involved segments of bowel is advocated.

Adult↗