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Biomedical subjects

Y Lajat

Publications and source records attributed to Y Lajat.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

Role of Gd-DOTA in the evaluation and imaging of experimental blood-brain barrier disruption in brain edemas and their improvement after anti-inflammatory drugs treatment.

This study was carried out to evaluate the effect of new anti-inflammatory drugs in the treatment of brain edema in new models. Experimental brain edema was induced in rats by stereotaxic injection of phospholipase A2 into one hemisphere. Concentrations of intravenously injected gadolinium-DOTA in the lesioned hemisphere were three times as high as in normal rat hemisphere. Edema was reduced by treatment with anti-inflammatory drugs such as dexamethasone (P < 0.01) or an experimental benzamide drug (P < 0.02). Magnetic resonance imaging (MRI) was then used to evaluate edema reduction after administration of contrast medium. We observed weighted scans for control lesioned rats, a reduction of signal intensity after dexamethasone and no significant regression after the benzamide drug. For purposes of experimental brain edema research in rats, the MRI technique facilitates detection and evaluation of the anti-inflammatory activity of molecules crossing the blood-brain barrier.

Animals↗
PubMedDate not supplied

Effects of photodynamic therapy on adhesion molecules and metastasis.

Photodynamic therapy (PDT) induces among numerous cell targets membrane damage and alteration in cancer cell adhesiveness, an important parameter in cancer metastasis. We have previously shown that hematoporphyrin derivative (HPD)-PDT decreases cancer cell adhesiveness to endothelial cells in vitro and that it reduces the metastatic potential of cells injected into rats. The present study analyzes the influence of PDT in vivo on the metastatic potential of cancers cells and in vitro on the expression of molecules involved in adhesion and in the metastatic process. Photofrin and benzoporphyrin derivative monoacid ring A (BPD) have been evaluated on two colon cancer cell lines obtained from the same cancer [progressive (PROb) and regressive (REGb)] with different metastatic properties. Studies of BPD and Photofrin toxicity and phototoxicity are performed by colorimetric MTT assay on PROb and REGb cells to determine the PDT doses inducing around 25% cell death. Flow cytometry is then used to determine adhesion-molecule expression at the cell surface. ICAM-I, MHC-I, CD44V6 and its lectins (àHt1.3, PNA, SNA and UEA) are studied using cells treated either with BPD (50 ng/ml, 457 nm light, 10 J/cm2) or Photofrin (0.5 microgram/ml, 514 nm light, 25 J/cm2). Changes of metastatic patterns of PROb cells have been assessed by the subcutaneous injection of non-lethally treated BPD or Photofrin cells and counting lung metastases. First, we confirm the metastatic potential reduction induced by PDT with respectively a 71 or 96% decrease of the mean number of metastases (as compared with controls) for PROb cells treated with 50 ng/ml BPD and 10 or 20 J/cm2 irradiation. Concerning Photofrin-PDT-treated cells, we find respectively a 90 or 97% decrease (as compared with controls) of the mean number of metastases for PROb cells treated with 0.5 microgram/ml Photofrin and 25 or 50 J/cm2 irradiation. Then, we observe that CD44V6, its lectins (àHt1.3, PNA, SNA) and MHC-I are significantly decreased (compared with the other molecules tested) in PROb and REGb cells after both BPD and Photofrin PDT treatment. These modifications in adhesion-molecule expression, particularly of CD44V6, can thus account only for part of the decrease in the metastatic potential of PDT-treated cancer cells. Changes in adhesion-molecule expression induced by PDT are only transient, implying that the rate of metastatic reduction is probably not linked simply to these changes.

Animals↗
PubMedDate not supplied

[Comparative study of complications observed in ventriculo-atrial and ventriculo-peritoneal derivations. Apropos of 106 cases].

In this study that concerns 106 cases, authors insist on the frequency of the infectious and mechanical complications. They make a review of the etiologies and of the various materials used by themselves and study successively the mechanical, infectious and mixed complications, sector by sector. They drive, at each level, conclusions concerning the results with their subsequent lessons. Having recalled, in short, the principles of supervision of any child bearer of a "valve", they conclude by developing their present idea of the "ideal derivation" by on the base of the material submitted to experimentation. They insist on the value of the ventricular-peritoneal derivations in the new-born.

Catheterization↗
PubMedDate not supplied

[Value of angiography in the diagnosis of peripheral nerve tumors].

In current practice, arteriograpy is already acknowledged, at the present time, as a method of primary importance which cannot be dispensed withfor diagnosis, prognosis and treatment. By opposition, considering pathology of the peripheric nerves, arteriography is often overlooked before chirurgical exploration though it affords the same advantages as in the remaining fields of pathology. Technically our preference goes to selective angiography by direct puncture of humeral or femoral artery. Arteriography will permit:-Visualisation of the location of the tumor close to the major vessels;-Evidence of the exact site of the efferent and afferent pedicles;-Discovery of other localisation. Mostly arteriography helps preoperatively to histological diagnosis. It must be recalled that benign neurinomas often assume a misleading aspect on the tumorography with stagnation of the contrast medium which might suggest malignancy. These benign tumors have three peculiar features: 1. Arteries are observed to stretch out around the lesion but never to narrow. 2. There is no explosive vascularisation ; hypervascularisation appears progressively, is located on the periphery of the lesion, and occupies but a part of the whole area. 3. Veins are not invaded but pushed apart and duly appear in normal timing. This peculiar aspect is quite the opposite of what can be observed in malignant tumors, which are, by far, less frequent.

Adult↗
PubMedDate not supplied

[Deep hypotension induced by sodium nitroprusside in neurosurgery. II.--Cerebral hemodynamic effects and metabolic rate of oxygen (author's transl)].

The cerebral hemodynamic effects of sodium nitroprusside (S. N.) have been the object of animal studies mainly. During the only human study performed, the drop in mean arterial pressure (MAP) is limited to 67 mm Hg. The study of the evolution of cerebral blood flow (CBF) in cases of more severe hypotension (MAP less than 45 mm Hg) seems of some interest. The study was composed of the measurement of the CBF using Xenon 133 and the calculation of cerebral vascular resistances (CVR) as well as cerebral metabolic rate of oxygen (CMRO2). Eleven patients with an average age of 37 years underwent surgery for cerebral aneurism 10 to 15 days after the inaugural hemorrhagic accident, under narconeuroleptanalgesia and stable ventilatory conditions. They are divided into 2 groups: Group I, 9 patients with normal levels of consciousness; Group II, 2 patients either agitated or obnubilated. The study is composed of 3 successive measures: (1) (T0) during stable anesthesia just prior to hypotension; (2) (T1) after 5 minutes of hypotension (MAP = 40 +/- 7 MM Hg); (3) (T2) 20 minutes after having stopped S. N. infusion. For the 9 patients in Group I, CBF remains unchanged at T1, the CVR decreases (p less than 0.001) and CMRO2 decreases (p less than 0.05). At T2 all of these parameters return to T0 values. The postoperative clinical evolution is favorable and uncomplicated. For the 2 patients in Group II the CBF, initially higher, falls from 20 to 30 p. cent at T1 with a drastic reduction in CMRO2. Despite the improvement of these parameters at T2, a prolonged postoperative coma is observed. This study suggests that CBF and CMRO2 are important parameters to monitor during controlled severe hypotension. Decrease in MAP must be less than 50 p. cent of control value and time-limited.

Acid-Base Equilibrium↗
PubMedDate not supplied

[Tactical approach to tumours of the sacro-coccygeal region. Report of five cases (author's transl)].

The name of sacro-coccygeal tumors is used generally for various tumors embryologically different in their origin. Rare, but not exceptional in number, these sacro-coccygeal tumors may have various locations and different sizes which make diagnosis more or less difficult. Benign in the first months of life, risks of malignancy will increase with age. Systematical intrarectal exploration will help not to overlook pelvic forms and will recognize pelvic extension in other types. Once found out, the extension of these sacro-coccygeal tumors should be estimated by complementary examination choosen according to the presumed type of tumor and it is to be regretted that myelography should be so often neglected. Treatment should always be surgical with one piece aphotesis if possible; good preparation and exact reanimation of the child are necessary because sometimes surgical treatment may be a very severe aggression for small babies. Constant surgical and biological overall should be maintained for many years in order to discover as early as possible any local relapse or metastasis.

Barium Sulfate↗
PubMedDate not supplied

[Tuberculous abscess of the central nervous system (author's transl)].

A case of tuberculous abscess of the cerebellum is reported by the authors. A check-up of concerned literature of ten-past years is drawn up. Diagnosis is seldom raised before surgery in spite of former or evolved tuberculosis. Histology and bacteriology are essential for a supportive therapy. The prognosis is favorable in seventy three per cent of the cases. This pathology must not be forgotten in patients who imigrate from countries of high endemic level of tuberculosis.

Central Nervous System Diseases↗