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Biomedical subjects

L Rosa

Publications and source records attributed to L Rosa.

At least 37 records · Page 2Linked to original sources
PubMed1990

MRI characterization of 9L-glioma in rat brain at 4.7 Tesla.

In vivo estimation of intracranial tumor progression is important in tumor treatment response studies in animal models. High resolution MR images at 4.7 T of 9L-gliomas stereotactically implanted in Fisher-344 rat brains were obtained. Due to elongation of T1 at higher fields, tissue contrast is diminished in T1-weighted images. However, normal anatomy and vasogenic edema are clearly discerned in T2-weighted images (echo times of greater than 50 ms and recycle times of greater than 2 sec). Tumor tissue is not always clearly delineated. Images obtained after administration of contrast agents (Gadolinium DTPA), with short TR (0.6 sec) selectively enhanced the tumorous tissue, with little effect upon normal tissue and edema. Good correlation of enhanced tumor lesions has been observed with histological examination of formalin fixed brains. Relaxation times (T1 and T2) of tumor and normal tissues were measured using stimulated-echo and multi-echo sequences, respectively. Serial images corresponding to tumor growth were recorded, from which tumor volume progression was monitored.

Animals↗
PubMed1990

Transbilayer redistribution of phosphatidylserine in erythrocytes of a patient with autoerythrocyte sensitization syndrome (psychogenic purpura).

We have investigated a female patient with autoerythrocyte sensitization syndrome (AES syndrome), having a positive skin response to her own red blood cells (RBC) and to phosphatidylserine (PS). Using 2,4,6-trinitrobenzenesulfonic acid (TNBS), bee venom phospholipase A2 and merocyanine 540 binding, we have demonstrated that in RBC of patient more than 50% of PS is redistributed into the outer leaflet of the plasma membrane. Using homologous RBC from a healthy donor we were able to induce transbilayer PS redistribution by incubation with the patient plasma. The presence of immunoglobulin E against cardiolipin and PS was proved in patient's plasma. We elaborated a method for cytoskeleton visualization using indirect immunofluorescence technique. We found disorders in cytoskeleton organization in RBC of the patient. We recommend in vitro testing for AES syndrome diagnosis. The positive effect of chlorpromazine treatment is described.

Actins↗
PubMed1989

Rey-Auditory Verbal Learning and Rey-Osterrieth Complex Figure Design performance in Alzheimer's disease and closed head injury.

Performance on the Rey-Auditory Verbal Learning (R-AVL) and Rey-Osterrieth Complex Figure Design (R-O CFD) tests was examined in patients (N = 94) with dementia of the Alzheimer's type (DAT) and closed head injury (CHI). On the R-AVL, DAT patients demonstrated considerably greater impairment than CHI patients, along with a flat learning/retention curve that showed negligible improvement with repeated trials, recency effects only, and an excessive number of word intrusions (confabulation) on the recognition trial. CHI patients demonstrated both a recency and primacy effect along with improvement over repeated trials (positive slope learning curve). Both groups demonstrated impairment R-O CFD recall; the DAT group again displayed substantially greater copying and recall deficits. Clinical guidelines are given for the use of the R-AVL and R-O CFD for these two patient populations.

Adult↗
PubMed1989

Missed fractures of the cervical spine.

Two cases of missed injuries of the cervical spine are presented, with a description and a discussion of the circumstances of the injuries. This information hopefully will alert medical personnel to situations where these injuries may be overlooked.

Adult↗
PubMed1988

Personality/behavioral characteristics in children: differential effects of putative anterior versus posterior cerebral asymmetry.

The current study was carried out to examine the possible relationships among personality/behavioral characteristics and anterior/posterior (A/P) functional cerebral asymmetry in children referred for learning problems. Two hundred nineteen children between 7 and 12 years of age were administered a battery of neuropsychological measures, and their parents completed the Child Behavior Checklist (CBC) and the Personality Inventory for Children-Revised (PIC). Anterior and posterior composite scores were obtained for each subject using scores on the neuropsychological measures. Out of this subject pool, 33 children had sufficient anterior/posterior (A/P) score differences (i.e., greater than one standard deviation difference) to permit their categorization into either an A (n = 19) or P (n = 14) group. The MANOVA results showed that the A group scored significantly higher than the P group on the CBC scales of social withdrawal, aggressiveness, hyperactivity and externalizing, while the P group scored higher, though not significantly, on the (PIC) scale of anxiety. Thus, it appeared that, by using neuropsychological measures along the A/P dimension to classify children with learning problems, significant differences could also be identified on personality/ behavioral variables for some children. In addition, in the current study, children with A type functional cerebral asymmetry exhibited a relatively greater number of behavioral problems.

Journal Article↗
PubMed1986

Response variability of human brain tumors to AZQ in tissue culture.

In a series of 28 glioma-derived cell cultures and 6 non-gliomatous CNS tumors, AZQ has been found to have varying degrees of growth inhibiting or cytotoxic activity in nearly all lines tested at doses greater than 100 mcg/ml. At dose levels comparable to the clinically achieved levels (1 mcg/ml), AZQ was found to have a cytotoxic effect in 8 of 28 glioma-derived and 2 of 6 non-gliomatous cell lines tested. These findings suggest that AZQ has activity against certain glioma-derived cells in culture at a response ratio similar to that seen in vivo. There, appear to be significant differences in the degree of responsiveness in different patients' tumor cells which can be detected in vitro prior to clinical treatment.

Antineoplastic Agents↗
PubMed1984

Conditions Required for the Rapid Activation In Vitro of the Chloroplast Fructose-1,6-bisphosphatase.

Conditions required for the reductive activation of purified, spinach chloroplast fructose-1,6-bisphosphatase (EC 3.1.3.11) have been determined in vitro. Full reductive activation was observed only when fructose-1,6-bisphosphate and Mg(2+) were present at the same time as the reducing agent (dithiothreitol). Reduction in the absence either of fructose-1,6-bisphosphate or of Mg(2+) slowly and irreversibly inactivated the enzyme. The concentration of fructose-1,6-bisphosphate that must be present during reduction for maximum activation depends upon the divalent cation present: it is highest with Mg(2+), lower with Ca(2+), and lowest when both Mg(2+) and Ca(2+) are present. A scheme for the reductive activation and inactivation of the enzyme is presented.

Journal Article↗
PubMed1984

Cerebral arteriovenous malformations. Indications for and results of surgery, and the role of intravascular techniques.

To address the problems of surgical risk versus natural risk associated with cerebral arteriovenous malformations (AVM's), and the role of the intravascular operative approach, the authors have assessed a 20-year experience with 450 patients. Results of direct surgery in 90 patients indicate that for the smaller AVM's (Grades I and II), mortality and morbidity rates are lower than a reasonably projected natural risk. Hence, these patients are candidates for surgery in most instances. However, for more extensive AVM's (Grades III and IV), consideration of anticipated future years of exposure to natural risk and the location of the AVM in the brain are necessary for determining operability. In general, neither seizures nor incipient focal neurological dysfunction alone are indications for surgery, and the risks of disability or death from hemorrhage after the fifth decade of life are probably less than the surgical risks by present operative techniques. Considering the usual age of patients at the time of diagnosis, it is estimated that surgical risk is currently less than the natural risk for about 65% to 70% of all AVM patients. The categories of AVM's in which the angiographic effectiveness of the intravascular approach is the greatest correspond to the same categories of AVM's that can be surgically removed with low risk. The intravascular approach is most useful for management of large AVM's causing progressive neurological dysfunction or as a preliminary step to surgery in selected cases in which access to major feeding arteries is difficult. The authors believe that the future of the intravascular approach should be directed toward transforming large inoperable AVM's into operable ones, but that the overall capability for this with acceptable risk is uncertain at present.

Adolescent↗
PubMed1982

Estimate of the incidence and importance of circulatory breakthrough in the surgery of cerebral arteriovenous malformations.

Severe hemorrhagic brain swelling has been described occasionally in patients with cerebral AVMs after surgical interruption for feeding arteries, surgical excision, and embolization. The proposed mechanism is an abrupt increase in perfusion pressure in the vasculature of the normal adjacent brain which has lost its capacity to autoregulate. The term circulatory breakthrough has been adopted to describe this. The authors found its incidence to be 3 in 66 patients in a surgical series, but lesser degrees of circulatory breakthrough in smaller lesions may have accounted for most of mortality and morbidity that was encountered. Its importance in embolization is less certain because of the possibility of infarction. It is proposed that better control of this problem by presurgical embolization, surgical staging, and graduated degrees of induced hypotension postsurgery may be necessary if the larger cerebral AVMs are to be excised with mortality and morbidity less than the natural history.

Adult↗
PubMed1981

Uncouplers stimulate photosynthesis in intact chloroplasts by enhancing light-activation of enzymes regulated by the ferredoxin-thioredoxin system.

Some uncouplers stimulate CO(2)-dependent O(2) evolution by intact spinach chloroplasts at pH 8.6. This effect is not due to alkalinization of the stroma. The stimulation is observed only when photosynthesis has been partly inhibited by the presence of H(2)O(2), generated in a Mehler-type reaction by the broken chloroplasts which always contaminate the intact chloroplast preparations. The addition of methyl viologen increases the Mehler-type reaction and results in greater inhibition of photosynthesis. The addition of excess catalase stimulates photosynthesis by preventing accumulation of H(2)O(2). The uncouplers stimulate photosynthesis primarily by enhancing the light-activation of enzymes that are regulated by the ferredoxin-thioredoxin system, and this effect results from the influence of the uncouplers on the redox poising of the ferredoxin in the intact chloroplasts.

Journal Article↗