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Biomedical subjects

M Iturralde

Publications and source records attributed to M Iturralde.

At least 19 recordsLinked to original sources
PubMed1993

Adherence of ruminant mastitis Staphylococcus aureus strains to epithelial cells from ovine mammary gland primary cultures and from a rat intestinal cell line.

Staphylococcus aureus isolated from mastitis (14 bovine and 11 ovine strains) exhibited an ability to adhere to epithelial primary cultures from ovine mammary gland and to a rat epithelial cell line, RIE-1. Strain differences in the degree of adherence were observed in both cases. These differences were maintained when comparing different epithelial sources (rat vs. ovine). RIE-1 cells can thus be used as a model for studying staphylococcal adherence to epithelial cells. Changes in bacterial adherence were observed according to the bacterial growth phase. The magnitude of these changes differed among strains. Bacterial cell surface hydrophobicity was not related to the degree of adherence to mammalian epithelial cells.

Animals↗
PubMed1992

Effect of iron and retinoic acid on the control of transferrin receptor and ferritin in the human promonocytic cell line U937.

The effect of changes in iron availability and induction of differentiation on transferrin receptor expression and ferritin levels has been examined in the promonocytic cell line U937. Addition of iron (as 200 micrograms/ml saturated transferrin) or retinoic acid (1 microM) both caused approx. 70% reduction in the average number of surface transferrin receptors, while the iron chelator desferrioxamine caused an 84% increase. Comparable changes also occurred in the levels of transferrin receptor mRNA. Neither iron nor retinoic acid significantly altered the half-life of transferrin receptor mRNA in the presence of actinomycin D (approx. 75 min) but a 10-fold increase in stability occurred in the presence of desferrioxamine. Iron and retinoic acid both caused an increase in intracellular ferritin levels (approx. 4-and 3-fold, respectively), while desferrioxamine reduced ferritin levels by approx. two-thirds. The effect of iron and retinoic acid added together did not differ greatly from that of each agent alone. None of the treatments greatly affected levels of L-ferritin mRNA. Virtually no H-ferritin mRNA was detected in U937 cells. These results show that changes in ferritin and transferrin receptor caused by treatment with retinoic acid are similar to those induced by excess iron, and suggest that changes in these proteins during cell differentiation are due to redistribution of intracellular iron into the regulatory pool(s), rather than to iron-independent mechanisms.

Cell Differentiation↗
PubMed1992

An efficient microtest to study adherence of bacteria to mammalian cells.

A simple, fast and highly reproducible microtest was developed for in vitro adherence studies. A rat epithelial cell line was investigated for the adherence of clinical and subclinical ovine and bovine Staphylococcus aureus strains isolated from mastitis. Staphylococcus aureus strains differed in their ability to adhere to epithelial cells, the degree of adherence being dependent on the concentration of bacteria used in the test.

Animals↗
PubMed1991

Effect of alpha-fetoprotein and albumin on the uptake of polyunsaturated fatty acids by rat hepatoma cells and fetal rat hepatocytes.

The uptake of polyunsaturated fatty acids by rat hepatoma cells and fetal hepatocytes has been studied using albumin and alpha-fetoprotein (AFP) as carrier proteins. Both types of cells took up linoleic (18:2(n-6)) and linolenic (18:3(n-3)) fatty acids at the same rate when they were added complexed either to albumin or AFP at a 1:1 molar ratio. At 37 degrees C a greater incorporation of arachidonic acid (20:4(n-6)) and mainly docosahexaenoic acid (22:6(n-3)) was observed when these acids were bound to albumin (6.5 nmol 20:4(n-6); 6.4 nmol 22:6(n-3) /million cells) as compared to AFP (5.5 nmol 20:4(n-6); 4.3 nmol 22:6(n-3)/million cells). The 20:4(n-6) and 22:6(n-3) uptake seems to be inversely related to the apparent association constants (k'a) between these fatty acids and both proteins (1.3 and 1.5 x 10(-7) M-1 20:4(n-6) and 22:6(n-3) for albumin; 6.4 and 54.0 x 10(-7) M-1 20:4(n-6) and 22:6(n-3) for AFP). Experiments carried out at 4 degrees C indicated that binding of 20:4(n-6) (0.83 nmol/million cells in presence of albumin; 2.16 nmol/million cells in presence of AFP) and 22:6(n-3) (0.83 nmol/million cells in presence of albumin; 1.32 nmol/million cells in presence of AFP) by cell membranes was also inversely related to the k'a of these proteins. At 4 degrees C, the k'a of AFP and albumin for 20:4(n-6) and 22:6(n-3) changed considerably (12.7 and 9.6 x 10(-7) M-1 20:4(n-6) and 22:6(n-3) for albumin; 3.9 and 14.6 x 10(-7) M-1 20:4(n-6) and 22:6(n-3) for AFP) with respect to the k'a calculated at 37 degrees C. Hence, k'a values were higher for albumin and lower for AFP than the corresponding values at 37 degrees C. It was concluded that uptake by cells and interaction of fatty acids with cell membranes depend mainly on the k'a of fatty acids and carrier proteins at equilibrium.

Animals↗
PubMed1990

Linoleate and linolenate desaturation by rat hepatoma cells.

Morris 7777 rat hepatoma cells in culture possess high delta 6 and delta 5 desaturase activities over linolenic acid added to the medium as albumin or alpha-fetoprotein complexes. After 2 hours incubation with [1-14C] linolenic acid (7 microM), around 40% of the radioactivity was recovered in other polyene fatty acids, mainly pentaenes. After 24 hours incubation with this substrate the polyene derivatives raised to more than 60%. However, [1-14C] linoleic acid was poorly converted to other polyene fatty acids. Linoleic acid up to 58 microM concentration in the medium do not inhibited linolenic acid desaturation. Long-term supplementation with 50 microM linoleic or linolenic acid, which modified the fatty acid profile of hepatoma lipids, enhanced the desaturase activities against linoleic acid. Desaturase activities were not affected by the fatty acid protein carrier, alpha-fetoprotein or albumin.

Animals↗
PubMed1989

Interaction of rat alpha-fetoprotein and albumin with polyunsaturated and other fatty acids: determination of apparent association constants.

The interaction of fatty acids with rat alpha-fetoprotein and albumin was measured using a partition equilibrium method. alpha-Fetoprotein (AFP) displays one high-affinity binding site for fatty acids and albumin near two binding sites. The AFP association constants for most fatty acids were similar to those of albumin (in the 10(7) M-1 range) whereas for docosahexaenoic acid it was 9.7 x 10(8) M-1, about 50-fold higher than that corresponding to albumin. This difference justifies docosahexaenoic acid in fetal or neonatal serum being mainly bound to AFP and can indicate a highly specific role of AFP in the transport of this fatty acid.

Animals↗
PubMed1988

The role of nuclear cardiology procedures in the evaluation of cardiac function following heart transplantation.

Heart transplantation is, today, an accepted and recommended modality in the management of selected patients suffering from terminal heart disease. However, acute rejection and infection remain the major complications of this operation. Serial endomyocardial biopsy (EB), considered as the standard for diagnosis of cardiac rejection, is an invasive and delicate operation, not free of complications, even when done by skilled personnel in specialized centers. The object of this study was to compare and correlate between radionuclide ventriculography (RNV) and the histologic findings of EB. Furthermore, to validate the use of nuclear cardiology techniques that allow noninvasive, reliable, and rapid quantitation of ventricular function and myocardial perfusion for the diagnosis and management of rejection in patients with heart transplants. Radionuclide studies of left ventricular function were performed in 3 heterotopic heart transplant patients (HHT) with long term survival and early after the operation in 5 patients with HHT, 12 orthotopic heart transplants (OHT) and in 2 heart and lung transplants (HLT). Simultaneous EBs were performed in the early posttransplant patients and a histologic score for acute rejection was obtained. First pass (FP) and multigated equilibrium blood pool ventriculography, using the in vivo 99mTc-labelling of RBCs was used to measure left ventricular volumes (LVV) such as stroke volume (SV), end-diastolic volume (EDV), end-systolic volume (ESV), and both global and regional ejection fraction (EF, REF). The histological grading of acute rejection was classified into four groups: (1) no rejection, (2) mild rejection, (3) moderate rejection, and (4) severe rejection. The median of each LVV parameter was calculated and correlated with the EB using a nonparametric one way analysis of variance. A percentage change of LVVs was used rather than the difference of the calculated LVVs. During moderate acute rejection, SV had the highest correlation in P less than 0.004, followed by the EDV (P less than 0.05), and finally ESV (P less than 0.02). During severe acute rejection the correlation was SV (P less than 0.0008), EDV (P less than 0.001), and ESV (P less than 0.006). Myocardial perfusion scintigraphy using 201T1 was performed in the HHT patients, although, at this stage we have not attempted a correlation with the histologic findings. In one patient with long term survival OHT, increased 131I-metaiodobenzylguanidine (MIBG) myocardial uptake was evident during a rejection episode.

Adolescent↗
PubMed1985

Radionuclide studies in upper gastro-intestinal ulceration--are they reliable? A pilot study of 6 patients.

Endoscopy is at present the diagnostic technique of choice in the evaluation and detection of upper gastro-intestinal tract ulceration. Because of the physical discomfort suffered by patients during endoscopic examination, the search for better and less invasive methods of examination (especially in the unco-operative and seriously ill patient) continues. According to reports from the Orient, sucralfate (Ulsanic; Continental Ethicals) has prominent ulceravid properties. These properties are being used in conjunction with a tagging agent, in this case technetium-99m, as a diagnostic method for the detection and localization of upper gastro-intestinal ulceration. In this pilot study on 6 patients the positive findings of others regarding the specificity and promise of this method could not be confirmed.

Aged↗
PubMed1985

Assessment of ventricular function by radionuclide angiography in patients receiving 4'-epidoxorubicin and mitoxantrone.

Serial assessment of ventricular function by means of radionuclide angiography was performed in 50 patients with malignant neoplasms who received either 4'-epidoxorubicin or mitoxantrone for longer than 3 months. In 9 of 30 patients given 4'-epidoxorubicin, a decrease of greater than or equal to 10% in the left ventricular ejection fraction (LVEF) was documented at doses of 143-1200 mg/m2. Two patients developed clinical signs of cardiotoxicity at a dose of greater than 1000 mg/m2. In 6 of 20 patients given mitoxantrone a decrease of greater than or equal to 10% in the LVEF occurred at doses of 26-98 mg/m2.

Adolescent↗
PubMed1984

High stability hybrids producing monoclonal antibodies against human C-reactive protein.

This report shows how high stability hybrids producing monoclonal antibodies against human C-reactive protein were raised and selected. Monoclonal antibodies can be produced in large enough quantities through this method, to allow for the design and use of quantitative C-reactive protein determination on a clinical scale. This novel strategy consisted of the following: growing the hybrids and freezing them before cloning in order to assure stability and selecting the hybrids from those producing high titres in mouse ascite induction. Two monoclonal antibodies of high stability and great potential for large scale production have been developed in this manner. Production on a large scale of these monoclonal antibodies against human C-reactive protein can be useful both in clinical quantification and in physiological studies concerning its still unknown in vivo function.

Animals↗
PubMed1983

Amsacrine cardiotoxicity: assessment of ventricular function by radionuclide angiography.

Serial assessment of ventricular function by means of a nuclear medicine technique was performed in six patients with malignant disease receiving chemotherapy with amsacrine. Two patients who received treatment long enough so that greater than 580 mg/m2 of the drug was administered showed a significant decrease in left ventricular ejection fraction. Four patients who received total doses of 325-510 mg/m2 of amsacrine did not experience significant change in their cardiac function.

Aged↗
PubMed1981

[Radionuclide exercise gated studies in female patients with positive exercise electrocardiogram].

Radionuclide left ventricular ejection fraction (LVEF) has been determined in a group of 14 female patients at rest and during graded supine bicycle exercise. One group consisted of 9 patients complaining of chest pain and demonstrating positive exercise electrocardiography (EECG), but with normal contrast angiographic results. The second group of 5 patients had a normal response to EECG and was used as a control group. LVEF increased markedly in both groups during exercise. This study confirms the known fact of high false-positive EECG in female patients and that exercise radionuclide LVEF response can be used as a final screening test for cardiac catheterization in female patients demonstrating positive EECG.

Adult↗
PubMed1981

Hysterosalpingo-radionuclide scintigraphy (HERS).

A radionuclide procedure, hysterosalpingo-radionuclide scintigraphy (HERS), was designed to evaluate the migration of a particulate radioactive tracer from the vagina to the peritoneal cavity and ovaries as well as to image and functionally outline the patency of the pathways between these two extremes of the female reproductive system. Technetium-99m human albumin microspheres (99mTc-HAM) were deposited in the posterior fornices of patients who were divided into two specific groups. Group I consisted of patients who were to undergo different elective gynecologic operations, in which besides obtaining sequential images, radioactivity levels were measured in the removed organs and tissues. Group II consisted of patients referred by the Infertility Clinic for evaluation of their reproductive system pathways patency. In this latter group, HERS was compared with contrast hysterosalpingography (HSG) and peritoneoscopy (PCP). The results obtained from measurements of radioactivity levels on the removed surgical specimens and comparison with other conventional gynecologic diagnostic procedures provide accurate evidence of the migration of 99mTc-HAM from the vagina, through the uterus and tubes, to the peritoneal cavity and ovaries, and show that HERS is a simple noninvasive method for functionally imaging and assessing the patency of the female reproductive system pathways.

Female↗
PubMed1979

Global and regional assessment of cardiac performance by ECG-gated radionuclide blood pool imaging.

A non-invasive method for evaluation of regional and global ventricular function by ECG-gated radionuclide blood pool imaging was developed. Cinematic image display is a sensitive method for evaluating wall motion to detect regional ventricular abnormalities and chamber size. A value of r = 0,86 and 0,85 was found for both fixed and variable area radionuclide methods when these ejection fraction values were correlated with cardio-angiographic ejection fraction values in normal subjects and in patients with myocardial infarction. The fixed area method underestimated the ejection fraction in patients with mitra valve stenosis, but this problem can be overcome with the variable area method. The technique developed cannot be used in patients with severe arrhythmias (r = 0,49 and 0,44).

Blood Circulation↗
PubMed1979

Migration of a particulate radioactive tracer from the vagina to the peritoneal cavity and ovaries.

In this report we describe a radionuclide procedure designed to evaluate the migration of a particulate radioactive tracer from the vagina to the peritoneal cavity and ovaries, as well as the determination of the patency of the pathways between these two extremes of the female reproductive system. 99mTc-labelled human albumin microspheres (99mTc-HAM) were deposited in the posterior fornices of 24 patients a day before they were to undergo different gynaecological operations. During this period sequential images were obtained and after the operation radioactivity levels in the removed organs and tissues were counted with a scintillation detector. In 14 out of 21 cases, the ovaries and fallopian tubes were counted separately from the uterus. Nine were positive (radioactivity levels were sufficiently high in the tubes and ovaries) and 5 were negative (no substantial radioactivity levels could be detected in either the tubes or the ovaries). The 5 negative results all occurred in patients with proved tubal damage as a result of previous infection. All the results were either true positive or true negative, providing evidence of migration, or obstruction, of 99mTc-HAM from the vagina through the uterus and tubes to the peritoneal cavity and ovaries.

Adult↗
PubMed1979

A krypton-81m generator for organ ventilation and perfusion investigations.

A sterile pyrogen-free generator for ultra-short half-life 81mKr has been developed. During initial loading, the binding efficiency of 81Rb is 90--99%. The count rate during perfusion is 3 x 10(5) counts per minute for a 1,9 GBq (50 mCi) 81Rb generator. The generator has been used for routine and special investigations of lung perfusion and ventilation and for myocardial perfusion during catheterization.

Heart↗