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Biomedical subjects

M Colombi

Publications and source records attributed to M Colombi.

At least 55 records · Page 3Linked to original sources
PubMed1991

Altered fibronectin mRNA splicing in skin fibroblasts from Ehlers-Danlos syndrome patients: in situ hybridization analysis.

The expression of fibronectin (FN) mRNA isoforms generated by alternative splicing of the EDA region was studied by dot-blot and in situ hybridization, using specific FN cDNA probes, in skin fibroblasts from controls and Ehlers-Danlos Syndrome (EDS) patients (types III, IV, VII and non classified). An Image Analysis program was used for the quantitative evaluation and comparison of FN mRNAs levels in the different cell strains. The in situ hybridization analysis showed that FN mRNAs are homogeneously expressed in all cells of each fibroblast strain analyzed. While in control fibroblasts about 70% of FN mRNA isoforms contain the EDA region (EDA+ FN mRNAs), in EDS fibroblasts this fraction is reduced up to about 30%. This indicates that in the EDS fibroblasts analyzed a deregulation of the alternative splicing processes acting at the EDA region takes place.

Autoradiography↗
PubMed1990

The effect of dermatan sulfate on in vitro human plasma coagulation, platelet aggregation and beta TG/PF4 release.

We evaluated the in vitro anticoagulant action of dermatan sulfate (DS) (aPTT, antiXa, anti-thrombin) and its effect on human platelet aggregation and beta TG/PF4 release induced by threshold doses of aggregating agents, compared with standard heparin (SH). In pooled plasma, DS prolonged aPTT much less than SH, had no measurable antiXa activity, showed an anti-thrombin activity similar to that shown by SH at a tenfold higher dilution. DS had no direct effect on human platelet aggregation and beta TG/PF4 release. Moreover it did not significantly affect platelet aggregation and release by ADP and collagen, whereas it completely inhibited platelet aggregation and beta TG/PF4 release by thrombin. These data in vitro confirm that thrombin inhibition induced by DS is accompanied by a far lesser aPTT prolongation compared to heparin, without any appreciable interference with platelet function.

Adenosine Diphosphate↗
PubMed1990

Changes in the acinar activity patterns of phosphoenolpyruvate carboxykinase in livers of male and female rats upon feeding a high protein and a high fat diet.

Phosphoenolpyruvate carboxykinase (PEPCK) activity was investigated in relation to its localization within the liver acinus of male and female rats after feeding either a high protein diet (77%) or a high fat diet (52%). Both diets led to sex-dependent changes in activity and acinar distribution patterns. In male rats high protein diet provoked a shift in the acinar activity pattern towards the perivenous parts of the acinus without increase in average activity. Yet in the livers of females the activity was increased in all parts of the acinus, but to a greater extent in the perivenous parts of the acinus. Feeding a high fat diet increased PEPCK activity in males and to an even greater extent in females. In both sexes the increase was greater in the perivenous zone when compared to the changes within the periportal zone. The results are discussed in relation to changes in the concentrations of glucoregulatory hormones.

Animals↗
PubMed1990

The development of the acinar heterotopic pattern of phosphoenolpyruvate carboxykinase activity in the newborn rat.

The postnatal appearance of phosphoenolpyruvate carboxykinase activity (PEPCK) and acinar heterotopy was investigated in newborn rats aged 2 h, 12 h, 24 h and 3 days, as well as in juvenile rats aged 25 days. The livers showed an almost homogeneous distribution of activity along the sinusoidal length at the beginning of extrauterine life where energy needs are greatest. Compared to rats aged 2 h, the PEPCK activity was higher in the livers from rats aged 12 h. The increase in activity was most pronounced in the intermediary zone. After 24 h of extrauterine life the activity decreased again creating a homogeneous acinar activity pattern. By day 3 activity had increased in the periportal zone, while decreasing in the perivenous zone, resulting in a periportal to perivenous gradient. By day 25 total activity had reached highest values both in males and females, due to a relatively high perivenous activity. The more prominent acinar gradient corresponded approximately to the one seen in adult animals.

Aging↗
PubMed1990

Enzyme activity patterns of phosphoenolpyruvate carboxykinase, pyruvate kinase, glucose-6-phosphate-dehydrogenase and malic enzyme in human liver.

The distribution patterns of the enzyme activities of phosphoenolpyruvate carboxykinase, pyruvate kinase, glucose-6-phosphate-dehydrogenase and malic enzyme were determined in the liver acini of men and women by microquantitative means. The activity of PEPCK was higher in men compared to the activity in women. In both sexes no heterotopic distribution pattern was observed. PK activity of men was higher, but in both sexes no heterotopic distribution was detectable. G6PDH and ME showed relatively low activity. The distribution of G6PDH and ME activity was to some extent different in men and women. Yet their heterotopic patterns were not particularly distinct.

Female↗
PubMed1990

The effects of acetylsalicylic acid on phosphoenolpyruvate carboxykinase activity and acinar heterotopy in livers from juvenile and adult rats.

Male and female juvenile as well as adult rats were treated with acetylsalicylic acid in order to examine the effect of the drug on over-all activity and activity distribution of phosphoenolpyruvate carboxykinase (PEPCK) in the liver acinus. Upon administration of acetylsalicylic acid PEPCK activity increased in juvenile males and adult females, but was reduced in juvenile females and adult males. The periportal-perivenous activity gradient along the sinusoidal length, which is flatter in untreated juvenile rats compared to the livers of adult rats, was distinctly steepened by acetylsalicylic acid treatment. Acetylsalicylic acid did not affect the gradient in adult rats.

Aging↗
PubMed1990

Study of fibronectin expression in tumour cells by dot-blot and in situ hybridization: quantitative evaluation by image analysis.

An Image Analysis program was used for the quantitative evaluation and comparison of the fibronectin (FN) mRNA detected by dot-blot and in situ hybridization in different cell lines. These techniques were applied for the evaluation of FN mRNA synthesized by human normal fibroblasts (Flow 7000) and by four tumour-derived cell lines (HeLa, epithelioid carcinoma; 8387, fibrosarcoma; RD, rhabdomyosarcoma; SK Hep-1, hepatocarcinoma). Dot-blot analysis showed that the cell types analysed synthesize different levels of FN mRNA. Flow 7000 are the highest producers while HeLa the lowest. In situ hybridization confirmed these results and furthermore showed that while Flow 7000, 8387 and HeLa cells synthesized homogeneous levels of FN mRNA, RD and SK Hep-1 could be subdivided into two populations expressing high or low levels of FN mRNA. The combined analysis of dot-blot, in situ hybridization and Image Analysis allowed the quantitation of the number of FN mRNA molecules expressed by single cells. This approach is therefore an invaluable tool when evaluating mRNA expression in heterogeneous cell populations like tumour-derived cell lines, during cell cycle or in histological tissue sections.

Cell Line↗
PubMed1990

The heterotopic effects of insulin and glucagon on the acinar activity pattern of phosphoenolpyruvate carboxykinase in male and female rat liver.

The effects of the administration of insulin and glucagon on the intraacinar heterotopy of phosphoenolpyruvate carboxykinase (PEPCK) were investigated in male and female rat liver. Insulin did not noticeably influence PEPCK activity or its acinar distribution, either in males or in females. But it affected the activities of glucose-6-phosphate dehydrogenase and malic enzyme. Glucagon in supraphysiological concentrations led to an induction of PEPCK activity. Despite high glucagon concentration along the whole sinusoidal length, the inducing effect of glucagon was most pronounced in the periportal and intermediary parts of the acinus; thus indicating that there is no direct interrelationship between local glucagon concentration and PEPCK activity. In both experiments blood glucose levels were kept fairly constant.

Animals↗
PubMed1989

Bone marrow and tissue expression of gpIIb/IIIa, LFA-1, Mac-1 and gp150,95 glycoproteins.

Monoclonal antibodies (MAbs) against platelet glycoprotein gpIIb/IIIa and the leucocyte adhesion molecules LFA-1, Mac-1, and gp 150,95 alpha chain (CD11a,b,c) and beta chain (CD18) have been tested in normal and leukaemic bone marrows, in different human tissues, and in a patient with leucocyte adhesion deficiency (LAD). The effect of these MAbs on platelet aggregation was also tested. GpIIb/IIIa showed widespread distribution, while reactivity of CD11/18 antibodies was limited to haematopoietic cells. Platelets and megakaryocytes were reactive with one CD11a (25.5.2), and with no CD11b/c or CD18 MAbs. GpIIb/IIIa was present on the platelets of the patient with LAD, whereas 25.5.2, (CD11a) bound to his platelets but not to his leucocytes. These data indicate that LFA-1, Mac-1, and gp150,95 are not present on human platelets, but they suggest the existence of crossreacting epitopes on gpIIb/IIIa, which is consistent with the hypothesis that these molecules belong to a supergene family of adhesion molecules.

Antibodies, Monoclonal↗
PubMed1989

Platelet dysfunction in acute megakaryoblastic leukemia.

Platelet function profiles were studied in 3 patients with megakaryoblastic leukemia. All patients had a moderate decrease in platelet counts with abnormal platelet retention. One patient who developed hemorrhagic diathesis had prolonged bleeding time. In all patients platelet aggregation was defective after the addition of ADP, collagen, adrenaline, or U46619, a thromboxane A2 agonist. Malondialdehyde was reduced in all patients, as was platelet serotonin. Plasma beta-thromboglobulin levels were normal in all cases whereas PF4 was markedly elevated in one. Platelet dysfunction was not reversed by clinical remission. These studies confirm that megakaryoblastic leukemia is associated with a thrombocytopathy which may play a role in hemorrhagic diathesis and should be taken into account in the management of these patients.

Blood Platelets↗
PubMed1987

Acute gangrene of the scrotum and penis in four hematologic patients. The usefulness of hyperbaric oxygen therapy in one case.

We describe four cases of Fournier's gangrene complicating the postchemotherapy aplastic phase (polymorphonuclear cells [PMN] less than 500/microliter) in three patients with acute leukemia and one patient with non-Hodgkin's lymphoma. Blood and local cultures from two patients contained Pseudomonas aeruginosa, and local cultures from another patient grew both P. aeruginosa and Proteus rettgeri. Early recognition and aggressive antibiotic and surgical treatment with granulocyte recovery were fundamental factors in resolution of the gangrene in three of the four patients. Hyperbaric oxygen therapy, never reported in hematologic patients, was also very useful in one patient in whom the clinical course was particularly acute.

Adolescent↗
PubMed1987

Thromboembolic and other events following valve replacement in a pediatric population treated with antiplatelet agents.

To determine if anticoagulation therapy is necessary after valve replacement with the St. Jude Medical prosthesis in young subjects, 30 consecutive patients were studied. They ranged in age from 4 to 20 years, and each had undergone valve replacement some time between February, 1982, and June, 1984. There was 1 hospital death (3.3%; 70% confidence limits [CL] = 0.4% to 10.9%). The 29 hospital survivors were treated with aspirin and dipyridamole. All patients were followed up. There were 5 late deaths (17.2%; 70% CL = 9% to 27%), at a mean of 8 months postoperatively. Follow-up revealed that 7 thromboembolic events occurred in 7 of the hospital survivors (24.1%; 70% CL = 15% to 35%). Hemiparesis occurred in 1 patient, and documented valve thrombosis and death occurred in another. Transient sensorimotor deficits were found in the 5 other patients. Prosthetic valve endocarditis developed in 1 hospital survivor (3.5%; 70% CL = 0.4% to 11%) and resulted in late death. There were no reoperations in the hospital survivors. We conclude that the St. Jude Medical prosthesis is useful for valve replacement in the young because of its low profile, durability, and hemodynamic characteristics. However, we recommend that these patients receive full anticoagulation therapy.

Adolescent↗