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Biomedical subjects

M Avella

Publications and source records attributed to M Avella.

At least 37 records · Page 2Linked to original sources
PubMed1997

Fish gill respiratory cells in culture: a new model for Cl(-)-secreting epithelia.

Primary cultures of sea bass gill cells grown on permeable membranes form a confluent, polarized, functional tight epithelium as characterized by electron microscopy and electrophysiological and ion transport studies. Cultured with normal fetal bovine serum (FBS) and mounted in an Ussing chamber, the epithelium presents a small short-circuit current (Isc: 1.4 +/- 0.3 microA/cm2), a transepithelial voltage (Vt) of 12.7 +/- 2.7 mV (serosal positive) and a high transepithelial resistance (Rt: 12302 +/- 2477 omega x cm2). A higher degree of differentiation and increased ion transport capacities are observed with cells cultured with sea bass serum: numerous, organized microridges characteristic of respiratory cells are present on the apical cell surface and there are increased Isc (11.9 +/- 2.5 microA/cm2) and Vt (25.9 +/- 1.7 mV) and reduced Rt (4271 +/- 568 omega x cm2) as compared with FBS-treated cells. Apical amiloride addition (up to 100 microM) had no effect on Isc. The Isc, correlated with an active Cl- secretion measured as the difference between 36Cl- unidirectional fluxes, was partly blocked by serosal ouabain, bumetanide, DIDS or apical DPC or NPPB and stimulated by serosal dB-cAMP. It is concluded that the chloride secretion is mediated by a Na+/K+/2Cl- cotransport and a Cl-/HCO3- exchanger both responsible for Cl- entry through the basolateral membrane and by apical cAMP-sensitive Cl- channels. This study gives evidence of a functional, highly differentiated epithelium in cultures composed of fish gill respiratorylike cells, which could provide a useful preparation for studies on ion transport and their regulation. Furthermore, the chloride secretion through these cultures of respiratorylike cells makes it necessary to reconsider the previously accepted sea water model in which the chloride cells are given the unique role of ion transport through fish gills.

Animals↗
PubMed1997

Chloride channels in primary cultures of seawater fish (Dicentrarchus labrax) gill.

Patch-clamp experiments were undertaken on primary cultures of respiratory cells originating from sea bass (Dicentrarchus labrax) gills. A small-conductance Cl- channel of 8 pS was characterized in cell-attached configuration with 140 mM N-methyl-D-glucamine-Cl in the pipette and bath solutions. No activity was recorded below a membrane holding potential of +20 mV (-Vp, referenced to the pipette solution), and the channel showed an inward rectification. In the inside-out configuration the Cl- channel was active at all membrane holding potentials. Its open probability strongly increased with membrane depolarization. The channel activity could be increased by the application of protein kinase A+ATP. This channel was inhibited by 5-nitro-2-(3-phenylpropylamino)-benzoic acid, diphenylamino-2-carboxylic acid, and I- and was insensitive to 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. The presence of Cl- channels in the apical membrane of respiratory cells provides additional evidence for an important role of this cell type in the control of ion homeostasis of seawater fish.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1996

Differential effects of chylomicron remnants derived from corn oil or palm oil on bile acid synthesis and very low density lipoprotein secretion in cultured rat hepatocytes.

The effects of chylomicron remnants derived from corn oil (rich in n-6 polyunsaturated fatty acids) and palm oil (rich in long chain saturated fatty acids) on bile acid synthesis and very low density lipoprotein secretion in cultured rat hepatocytes were studied. Incubation of the cells with corn oil remnants led to increased bile acid production, while the secretion of lipid in very low density lipoprotein remained unchanged. In contrast, addition of palm oil remnants to the medium did not affect bile acid synthesis, but resulted in the secretion of cholesterol-rich very low density lipoprotein. These findings show that chylomicron remnants of different fatty acid composition have differential effects on cholesterol metabolism in liver cells, and provide part of the explanation for the hyper- and hypocholesterolaemic effects of saturated and polyunsaturated fatty acids.

Animals↗
PubMed1995

Comparison of the hepatic uptake and processing of cholesterol from chylomicrons of different fatty acid composition in the rat in vivo.

The effect of the fatty acid composition of chylomicrons on the uptake and processing of the cholesterol they carry was investigated in the rat in vivo. Rats kept on a standard low fat pellet diet and tube fed a single dose of palm, olive, corn or fish oil (rich in saturated, n-9 monounsaturated, n-6 polyunsaturated and n-3 polyunsaturated fatty acids, respectively) were used to prepare [3H]cholesterol-labelled chylomicrons of different fatty acid composition. These were then injected intravenously into rats (kept on the standard diet), and the clearance of radioactivity from the blood, distribution in the plasma lipoprotein density fractions, uptake by the liver and appearance in the bile were studied. [3H]Cholesterol from fish and corn oil chylomicrons was cleared from the blood more rapidly than that from palm and olive oil chylomicrons. After 180 min the proportion of the radioactivity present in the plasma in high density lipoprotein (HDL) was less when the chylomicrons were derived from palm oil as compared to any of the other oils. Approx. 40% of the administered label was recovered in the liver after 180 min in all experiments. The percentage of the injected radioactivity secreted into bile during 180 min was significantly higher with corn and fish oil chylomicrons than with palm oil chylomicrons, with chylomicrons from olive oil in an intermediate position, and these differences were most pronounced between 60 and 120 min after administration of the label. These studies clearly demonstrate that the fatty acid composition of chylomicrons has important effects on the hepatic uptake and processing of the cholesterol they carry, with enrichment with polyunsaturated fatty acids leading to an increased rate of uptake and more rapid removal from the body via the bile as compared to enrichment with saturated or monounsaturated fatty acids.

Adrenal Glands↗
PubMed1994

Primary culture of gill epithelial cells from the sea bass Dicentrarchus labrax.

We have developed the first explant technique that allows the in vitro study of gill physiology and biochemistry in marine species. Gill fragments were cultured at 17 degrees C, in atmospheric PCO2, with nutrient medium (Leibovitz L15), pH 7.8, supplemented with 10% fetal bovine serum and adjusted to the osmolarity of fish plasma (350 mOsm/liter). Coating plates with collagen, gelatin, or polylysin did not improve our results. Decrease in osmotic pressure, removal of bovine serum, or its replacement by fish serum inhibited growth from the explants. Approximately 50% of the explants produced cell growth, and after 4 days of culture a monolayer of contiguous cells was formed. This technique is rapid and does not require the use of enzymes. The cells appeared flat and thin with an epitheloid shape. They looked polygonal with a maximum length of 10 to 50 microm. Evidence that they are unique gill cells is the presence of polymorphic surface crenelations (microplicae), prominent Golgi apparatus, tight junctions and desmosomes. Comparison with in vivo tissue showed them to be epithelial cells having differentiated in a homogeneous population of respiratory-like (pavement) cells. They are polarized with their apical surface facing the culture medium. The development of this culture system represents a new tool for cellular approaches to determine precisely the functions and transport mechanism of gill cells.

Animals↗
PubMed1993

Osteoporosis by ovariectomy: calcitonin effect in an experimental model on the rat.

The authors evaluate the efficacy of the aminosuberic derivative of eel calcitonin (eCT) in preventing post-ovariectomy osteoporosis in adult rats. The drug is administered in a dose of 0.5 U.I./day for four months starting from the moment of the ovariectomy. The results show that the treatment is efficacious in preventing bone mass loss due to ovariectomy and that the action of the drug does not bring about alterations in the normal crystalline structure of the bone.

Alkaline Phosphatase↗
PubMed1993

[Osteosarcoma of the extremities metastatic at presentation. Results obtained with primary chemotherapy followed by simultaneous resection of the primary and metastatic lesion].

From September 1986 to September 1990 35 patients affected by osteosarcoma of the extremities with synchronous metastasis were treated with two cycles of high-dose methotrexate IV, cisplatin IA and adriamycin IV followed, in 22, by simultaneous resection of the primary and metastatic tumor. Six patients progressed and were not operated on, 7 patients with complete response of pulmonary nodules underwent surgical resection of the primary lesion. A complete histological examination of the resected specimens was always performed to evaluate the percentage of necrosis produced by chemotherapy on both the primary and metastatic tumor. After surgery the patients received 3 more cycles of the same drugs as used preoperatively plus ifosfamide. The histological response of the primary tumour was "good" (90% or more tumour necrosis) in 8 patients (27%) and "poor" (less than 90% of tumour necrosis) in 21 (73%) while in the 75 metastatic nodules the resulting necrosis was good in 18 (24%) and poor in 57 (74%). A good correlation between the histological response in the primary and metastatic tumour was observed. At an average follow-up of 30 months (R 12-60), 13 patients are alive, 10 disease-free, and 3 with uncontrolled disease. This data suggest that prognosis of osteosarcoma of the extremities with synchronous metastases remains poor even with a very aggressive treatment. Our results also seem to confirm the validity of the present strategy in the treatment of non metastatic osteosarcoma: to introduce new drugs postoperatively in patients poor responder can allows a better treatment of microscopic disease and can improve the prognosis for these patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

[Effect of high and low doses of methotrexate (MTX) on bone mass in subjects treated for osteosarcoma of the limbs].

Twenty-three patients with highly malignant localized osteosarcoma receiving neoadjuvant chemotherapy with MTX randomly administered at high (7500 mg/m2) and low (750 mg/m2) doses underwent serial densitometric controls at the start of treatment and after 18 and 36 months. Increasing BMC levels at both examination points were observed in all subjects examined over time, but, contrary to findings in the control group, this increase was not statistically significant using the paired T test. Significantly lower BMC levels in relation to the control group were only found in the group treated with high doses of MTX at MDP but not PM. Reduced density at MDP alone, a site in which trabecular bone is prevalent, shows that MTX predominantly acts at the level of the latter in line with its greater sensitivity to the action of osteopenic agents.

Adolescent↗
PubMed1992

Osteosarcoma of the extremity metastatic at presentation: results achieved in 26 patients treated with combined therapy (primary chemotherapy followed by simultaneous resection of the primary and metastatic lesions).

From September 1986 to December 1989, 26 selected patients with high-grade osteosarcoma of the extremities metastatic at presentation were treated with primary chemotherapy (high doses of methotrexate, -cisplatinum and adriamycin) followed by surgery. Twenty-one cases underwent resections of the primary and metastatic tumor at the same time; owing to the disappearance of lung metastases after preoperative chemotherapy in 3 cases, only the primary tumor was operated on. Due to progression of the disease in 2 patients, no surgery was performed. Histologic examination of the resected specimen was performed to evaluate the percentage of necrosis produced by chemotherapy on the primary and metastatic tumor. After surgery, the patients received further chemotherapy with the same drugs used preoperatively plus ifosfamide and VP-16. The histologic response of the primary tumor was good (> 90% tumor necrosis) in 25% of the cases; in the resected metastatic nodules, 23% had good responses. A discrepancy between the histologic response of the primary and secondary tumor was observed in only 15% of the cases. These results seem to confirm the validity of the strategy (widely used today in the neoadjuvant treatment of non-metastatic osteosarcoma) of changing the postoperative treatment when the histologic response of the primary tumor is poor. At an average follow-up of 3.5 years, only 6 patients remained disease-free; 19 patients relapsed and 1 patient died for adriamycin cardiotoxicity. Of the 19 relapsed patients, 16 died and 3 are still alive but with uncontrolled disease. These results are much worse than those obtained in 144 cases of non-metastatic osteosarcoma of the extremities treated in the same period with the same preoperative chemotherapy (77% with good response in the primary tumor and 78% with continuous disease-free survival). The data suggest that a very effective neoadjuvant chemotherapy for nonmetastatic osteosarcoma of the extremities gives disappointing results in osteosarcoma of the extremities which is metastatic at presentation.

Adolescent↗
PubMed1992

Effects of starvation on valine and alanine transport across the intestinal mucosal border in sea bass, Dicentrarchus labrax.

Kinetics of intestinal transport of L-alanine and L-valine (substrates of the A-system and the L-system, respectively, in mammals) across the brush-border membrane in sea bass, Dicentrarchus labrax, were studied on intact mucosa using a short-term uptake technique. When fish were starved for 4-8 weeks, total influx (mucosa-to-cell) of valine fell owing to disappearance or modification of the diffusion component. The maximum influx rate of saturable component increased but its affinity (reflected by the Michaelis constant) decreased. Alanine transport by Na(+)-dependent and diffusion pathways was unchanged after starvation. Fasting also induced an almost 20% decrease in the length of intestinal microvilli.

Alanine↗
PubMed1992

Effect of intra-arterial versus intravenous cisplatin in addition to systemic adriamycin and high-dose methotrexate on histologic tumor response of osteosarcoma of the extremities.

In neoadjuvant treatment of osteosarcoma of the extremities intra-arterial (IA) instead of intravenous (IV) administration of cisplatinum (CDDP) has been advocated to improve local response and consequently increase the percentage of limb salvages and the cure rate. Since the major local advantages from the IA use of CDDP have been recently questioned, a comparative prospective study was performed at the Rizzoli Institute between July 1990 and September 1991. Preoperative chemotherapy consisted of two cycles of high-dose methotrexate (HDMTX), followed 6 days later by CDDP and adriamycin (ADM), HDMTX and ADM were delivered intravenously while CDDP was delivered according to previous randomization, either intra-arterially or intravenously. Of the 79 patients who entered the study 40 received CDDP IA and 39 CDDP IV. The percentage of clinical and radiological response of the tumor as well as the percentage of limb salvage procedures performed was the same in the two groups. However the rate of good histological response (tumor necrosis greater than 90%) was significantly higher in the group of patients who received IA CDDP than in the patients who received the drug intravenously (77.5% vs 46%: p less than 0.01). No differences in terms of local or systemic side effects were found in the two groups. A longer follow-up is necessary to establish if this improved good response rate achieved with IA CDDP will lead to an improved cure rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Primary chemotherapy and delayed surgery for osteosarcoma of the extremities with synchronous metastases.

From September 1986 to September 1989 11 patients affected by osteosarcoma of the extremities with synchronous metastases were treated with two cycles of high-dose methotrexate i.v., cisplatin i.a. and adriamycin i.v. followed by simultaneous resection of the primary and metastatic tumor. A complete histological examination of the resected specimens was always performed to evaluate the percentage of necrosis produced by chemotherapy on both the primary and metastatic tumor. After surgery the patients received 3 more cycles of the same drugs as used preoperatively plus ifosfamide. The histological response of the primary tumor was 'good' (90% or more tumor necrosis) in 4 patients and 'poor' (less than 90% of tumor necrosis) in 7, while in the 34 metastatic nodules the resulting necrosis was good in 8 and poor in 26. A good correlation between the histological response in the primary and metastatic tumor was observed, particularly for poor responders (91% of poor responses also in metastatic nodules). At an average follow-up of 42 months, only 3 patients are alive, 2 disease-free, and one with uncontrolled disease. These data suggest that the prognosis of osteosarcoma of the extremities with synchronous metastases remains poor, even with a very aggressive treatment. Our results also seem to confirm the validity of the present strategy in the treatment of non-metastatic osteosarcoma: introducing new drugs post-operatively in poor responding patients can allow a better treatment of microscopic disease and can improve the prognosis for these patients.

Adolescent↗