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J V Lafuente

Publications and source records attributed to J V Lafuente.

18 recordsLinked to original sources
PubMed2000

Influence of visual experience deprivation on the postnatal development of the microvascular bed in layer IV of the rat visual cortex.

Cerebral vascular density is correlated with metabolic demands, which increase in highly active brain areas. External inputs are an essential requirement in the modeling of the visual cortex. Experience-mediated development is very active during the first postnatal month, when congruous blood supply is needed. We studied the development of visual cortex vascularization in relation to experience, comparing rats raised in darkness with rats reared in normal conditions. Vascular density, vascular area and their ratio vs. neuronal density were calculated. Conventionally stained semi-thin sections were used to measure the vascular area by computer assisted morphometry. Animals from both groups were sampled at 14, 21, and 60 days postnatal (dpn). We found a significantly lower density of vessels and neurons as well as a smaller vascular area in dark-reared adult rats while no differences were founded at the other ages. Our results also show no differences between the ratio of vessels/neuron, and vascular area/neuron, between both groups. The absence of visual experience causes decrease of cortical activity which correlates with lower vessels density and vascular area, without their ratio/neuron being affected.

Age Factors↗
PubMed2000

Effects of chronic deep hypoxia on the expression of nitric oxide synthase in the rat brain.

Experimental studies in extreme hypoxic conditions affecting the brain have been performed mainly in acute but not chronic models. Twenty rats were housed and exposed to decreasing concentrations of oxygen (from 21% to 7% over 130 days) and ten normal rats were used as control. Paraffin slices from representative sections containing cerebral cortex, cerebellum, striatum, hippocampus, thalamus and hypothalamus were incubated with antisera against nitric oxide synthase. Cortex and striatum showed small randomly distributed positive neurons with bipolar features, in greater numbers in the hypoxic group (p < 0.02). The granular layer of the cerebellum showed a strongly positive rim around some cell nuclei. Purkinje cells were immunopositive in hypoxic rats. Hipoccampal, thalamic and hypothalamic nuclei showed no quantitative differences in the number of positive neurons. The increased number of blood vessels and their dilation observed in some brain regions in hypoxic rats, mainly in ventral striatum, lead us to hypothesise that NOS may be overexpressed and act at these sites as vasomodulator and/or mediator of secondary cell injury affecting selective neuronal populations. We conclude that prolonged periods of adaptation to deep hypoxia reduces the effect of hypoxia on the upregulation of NOS in the brain tissue.

Animals↗
PubMed2000

Biologic parameters that correlate with the prognosis of human gliomas.

Much clinical and biologic data have been processed in the search for useful objective parameters to predict brain tumor behavior. Seventy cases of astrocytic glioma collected by a single clinical team were studied using a full complement of clinical procedures: follow up (7 years), histologic analysis, DNA content estimation, and cell kinetics by flow cytometry. Proliferating cell nuclear antigen (PCNA) was determined by immunocytochemical-coupling flow cytometry (PFC) and also by counting under light microscopy (PIHC). A statistical evaluation was carried out to establish the usefulness of several parameters for glioma prognosis. The cases were histologically classified as 14 low-grade astrocytomas, 20 anaplastic astrocytomas, and 36 glioblastomas multiforme. The survival curve showed significant differences between histologic groups. Diploid populations were more frequent in low-grade astrocytomas, and aneuploid tumors often had increased S-phase and proliferative fractions. The PCNA-labeled index (PCNA-LI) increased with malignancy and correlated with histologic grading (P = 0.01). The PCNA-LI and age segregated low- from high-grade astrocytomas (including anaplastic astrocytoma and glioblastoma multiforme), but none of the variables considered differentiated anaplastic astrocytoma from glioblastoma multiforme. The Cox regression test displayed significant values for age, histologic diagnosis, and PCNA determinations when considered in tandem. Discriminant analysis obtained a function integrating age and specifically PIHC-LI to help in the prognosis of doubtful cases. The results emphasize the importance of parameters integrating different variables in an attempt to provide an accurate prognosis, the most significant being age, histopathologic diagnosis, and the proliferative fraction determined by PCNA.

Adult↗
PubMed1999

Craniocerebral trauma induces hemorheological disturbances.

Several mechanisms are involved in the development of secondary ischemic brain damage, including microthrombi formation, which is thought to play a prominent role. Ninety-four autopsy cases were macro- and microscopically examined by specific staining for fibrin, 74 of which showed cortical contusion after a craniocerebral trauma. Twenty cases with no neurological pathology were used as controls. Traumatic cases comprised 52 males and 22 females, with a mean age of 48 years; most cases died in the first 48 h. The total number of fibrinous microthrombi in a slice of each hemisphere was determined. The mean number of microthrombi found in contused hemisphere was 152 (37-283), with 88 in the contralateral hemisphere (21-139) as compared to 13 (0-27) in control cases. Differences were statistically significant. Globular microthrombi or "shock bodies" (2-60 micro diameter) were present in five cases. Enhanced presence of microthrombi in contused brain areas, higher incidence in young people, an increase in the amount of microthrombi up to the 9th day after injury and involvement of the contralateral hemisphere free of contusion foci were all demonstrated. Microthrombi would therefore seem to be one of the central secondary events after brain trauma to bear in mind when designing treatment strategies.

Adolescent↗
PubMed1998

[Biopathology of craniocerebral injuries: experimental models].

INTRODUCTION: In traumatic brain injury the secondary damage is responsible for the majority of the clinical and pathological sequels. This circumstance together with the difficulties of acquiring well preserved brain material for specialized neuropathological study impair the understanding of processes implied in their pathophysiology. DEVELOPMENT AND CONCLUSIONS: The development of experimental models has played an outstanding role for the better knowledge of these processes. For the development of standardized experimental models the biophysical and anatomical characteristics of brain and skull of the various utilized species have to be considered, but the physiological, neurochemical and molecular peculiarities must also be taken into account. Various in vivo models have been developed, inducing direct impact to the skull or to the brain, or mimicking lesions subsequent to craniocerebral trauma, such as subarachnoid hemorrhage, hematoma or necrosis. To analyze the molecular mechanisms of cellular response in vitro models have been developed. A great amount of cells in the contusional area die immediately following traumatic brain injury, but a still higher number of cells will undergo in the following hours. This second wave of neuronal death is induced by phenomena such as secondary axotomy and brain edema. In the pathogenesis of both the damage of cytoplasmic membrane is involved.

Animals↗
PubMed1996

Effects of dark-rearing on the vascularization of the developmental rat visual cortex.

Cerebral vascular density corresponds to metabolic demand, which increases in highly active areas. External inputs play an important role in the modeling and development of the visual cortex. Experience-mediated development is very active during the first postnatal month, when accurate simultaneous blood supply is needed to satisfy increased demand. We studied the development of visual cortex vascularization in relation to experience, comparing rats raised in darkness with rats raised in standard conditions. The parameters measured were cortical thickness, vascular density and number of perpendicular vessels, constituting the first stage of cortical vascular development. Vessels were stained using butyryl cholinesterase histochemistry, which labels some neurons and microvascularization (vessels from 5 to 50 microns). Animals from both groups were sampled at 0, 7, 14, 21 and 60 days postnatal. Vascularization of the brain starts with vertically oriented intracortical vascular trunks whose density decreases notably after birth in rats reared in standard laboratory conditions. The most striking finding of our work is the significantly lower decrease in the number of these vessels in dark-reared rats. Our results also show that cortex thickness and vessel density are significantly lower in dark-reared rats. These results suggest that the absence of visual stimuli retards the maturation of the visual cortex including its vascular bed.

Aging↗
PubMed1994

Evaluation of BBB damage in an UV irradiation model by endogenous protein tracers.

Autologous serum proteins have proved to be suitable tracer to evaluate vascular permeability. The dynamic behaviour of anti-HRP immunoglobulins was studied in ultraviolet (UV) irradiation induced brain edema. Cerebral cortex of 36 anaesthetized adult rats was irradiated following a 2 x 2 mm parietal craniotomy. Immunization was carried out by 3 subcutaneous injections of 10 mg HRP in 0.5 ml complete freund adjuvant (CFA), 6, 4 and 2 weeks before the injury. Control animals were immunized only with CFA; further control animals were operated and irradiated without any previous immunization. After survival times ranging from 30 min to 24 hours, postoperation animals were transcardially perfused with 4% fresh paraformaldehyde solution in phosphate buffered saline. After postfixation at 4 degrees C, 20 microns vibratome sections were prepared for incubation with a solution of 0.05% HRP, washed and developed by the DAB reaction. The reactions showed a remarkable exsudation and spreading of anti-HRP antibodies in the edematous brain. The antigen-antibody reaction was conspicuous in animals with shorter survival periods in the necrotic area and near the lesion (1-2 mm). After a longer survival time extravasation involved the whole hemisphere. In animals with the longest survival period labeled serum proteins were found even in the white matter of the hemisphere contralateral to the injury. Endogenous tracer of BBB function is useful to study the spreading of brain edema in a delayed time after the edematous lesion.

Animals↗
PubMed1994

Subcortical U-fibers layer preservation in brain edema.

The mechanism involved in the relative preservation of the subcortical U-fibers in the arcuate zone was studied in a post infarct edema after sagittal superior sinus occlusion. Superior sagittal sinus (SSS) of 36 mongrel cats were occluded by polymer injection. Immediately before the occlusion Evans-blue (EB) was administered intravenously. The cats were killed 1, 2, 3, 6, 12, 24, 72 and 120 hours after sinus occlusion. In 20 cats in which cortical veins were occluded, in addition to the SSS, EB was extravasated. In 9 of these cats, which had moderate edema, EB-staining was present only in the cortex. In 11 cats with severe edema, massive EB extravasation was observed also in the white matter. The U-fiber layer was free of EB, suggesting that the extension of edema was blocked by this zone. Our findings demonstrated that the U-fibers act not only as a resistance against extension of edema from white to gray matter, but also in a reverse direction. The characteristics of the spread of brain edema is not yet completely understood; both anatomical and biochemical peculiarities from its basis. Different morphological patterns in the astrocytic reaction as well as the U-fibers sector vascularization are important. To evaluate the role of each one of these factors in the preservation of subcortical U-fiber layer in brain edema further investigations should be done.

Animals↗
PubMed1992

Ultraviolet irradiation induced brain oedema in rats. A microgravimetric study.

The cerebral cortex of 36 anaesthetized Wistar rats were exposed to ultraviolet irradiation (UV-I) for 6 min through a 2 x 2 mm left parietal craniotomy. Animals were killed at different times and brains were removed immediately after death. Three consecutive coronal sections were obtained and sampled for gravimetric study. The density of the samples was measured using a continuous gradient of organic solvents. Gravimetric results showed significant differences between brain samples. The irradiated left hemisphere was less dense than the right one, and maximum differences in density were found in the medial coronal section. Grey and white matter oedema in the non-irradiated hemisphere was compared with the irradiated hemisphere. Early and delayed onset of odema was observed in both hemispheres but it was more marked in the irradiated hemisphere. In conclusion, brain oedema induced by ultraviolet irradiation in various animals is also reproducible in rats with all the advantages involved in the use of these experimental animals. Microgravimetric study correlated with topographical analysis using this model may lead to an understanding of some of the dynamic aspects of cerebral oedema.

Animals↗
PubMed1991

Traumatic brain injuries: structural changes.

A host of complications and consequences may follow a contusion or other brain injury of any sort. An appreciation of the temporal evolution of the contusion from a microscopic standpoint is useful to a full understanding of the process by which physical force damages the brain and how the brain reacts to this damage. Some disruptions of the blood brain barrier quite early will result in extracellular edema. The microscopic appearance of an edematous area is usually spongy with numerous vacuoles. The neuropil may appear bubbly, and glial cells may be swollen. If edema has been long standing, the vacuoles may be larger and in fact a small cyst may appear in the white matter. If focal cerebral edema is not present for long periods of time and the underlying cause has been corrected, residual fluid and electrolytes are eventually removed, restoring the neuropil to a normal state, leaving no sign of its presence. However, in longer standing lesions, myelin pallor and some reactive gliosis may remain indefinitely. Neurons may show swelling very early and for a short period of time, which gives way to shrinkage, eosinophilia, and nuclear pyknosis. These changes may be observed at the periphery of lesions for as long as 5 or 6 months after the initial event. Before dissolution, nuclear pyknosis may remain in the tissue for many days and possibly longer, and may even become mineralized in situ (ferruginated neurons) to remain for years. In a traumatic lesion, swollen and ballooned axons may be found in and around the contusion but also at great distances from it (diffuse axonal injury). Axonal ballooning may be observed between 24 and 48 h postinjury and may persist wherever found for many years. Selective axonal calcification has been observed in humans as well as in experimental trauma. At about 7-10 days postinjury increased numbers of astroglia probably are present. Over the ensuing weeks and months, and probably years, astrocytes increase in number and in fibrillary appearance, eventually resulting in a glial scar in and about the injured area. It is thought that this reactive gliosis results in restoration of the blood-brain barrier in the damaged area.

Astrocytes↗
PubMed1990

Dynamics of tracer distribution in radiation induced brain oedema in rats.

The dynamic behaviour of the distribution of Evans blue (EB), sodium fluorescein (SF), Lucifer yellow (LY) and horseradish peroxidase (HRP) was studied using standard light- and fluorescence microscopy following ultraviolet radiation induced brain oedema in the rat model. The cerebral cortex was irradiated after craniotomy (2 x 2 mm) under anaesthesia. The tracers were injected (iv) 30 min prior to radiation. Animals were perfused with glutaraldehyde through the heart at different survival periods ranging from 30 min to 24 h post irradiation. The results showed a remarkable difference in distribution and spread of these tracers in the oedematous brain following radiation. The extravasation of EB was evident in ipsilateral cortex 6 h after radiation which extended to the contralateral side at the end of the 24 h survival period. The HRP reaction product was seen in the necrotic area 3 h after radiation which further extended to the underlying white matter at 24 h survival. The LY stained the ipsilateral micronecrotic area 6 h after radiation, whereas a non-specific diffuse fluorescence of SF was noted at this time period. These results point out a specific selectivity of tracer distribution in oedematous brain following ultraviolet radiation.

Animals↗
PubMed1989

Pelizaeus-Merzbacher disease with thiamine deficiency or Leigh disease with extensive involvement of white matter? Case report.

We report on a case of a 30-month-old child who presented with a clinical syndrome compatible with leucodystrophy and in whom neuropathological features of both Pelizaeus-Merzbacher disease and subacute necrotizing encephalopathy were shown. The significance of the neuropathological findings is discussed in the light of a possible coexistence of both diseases which has not previously been reported.

Brain↗
PubMedDate not supplied

Expression of vascular endothelial growth factor (VEGF) and platelet-derived growth factor receptor-beta (PDGFR-beta) in human gliomas.

The growth of solid tumors is highly dependent on vascular proliferation. Vascular endothelial growth factor (VEGF), the main mediator of angiogenesis, and platelet-derived growth factor receptor-beta (PDGFR-beta), receptor for the potent mitogen PDGF, are two indicators of the angiogenic potential of human gliomas. We studied a series of 57 surgical biopsies of astrocytic neoplasms by immunohistochemistry to elucidate the relationship between tumor proliferation, quantified as Ki67-LI, and the expression of these two proteins. Ki67-LI increases throughout histological malignancy, although staining in endothelial cells has rarely been recorded. Elevated amounts of VEGF-positive tumor cells (VEGF-LI) were found in anaplastic astrocytomas and glioblastomas, mainly around areas of necrosis, cysts, or edema. Endothelium of blood vessels was consistently stained. PDGFR-beta positivity was found in glomeruloid formations and in tumor cells, excluding pilocytic astrocytomas. Multinucleated giant cells and perivascular tumor cells were positive in glioblastomas. In addition, peritumoral microglia-like cells were also stained in some cases. Statistical correlation was only found between PDGFR-beta and Ki67 LIs. In conclusion, VEGF as permeability factor is involved in the development of secondary neoplastic changes, whereas PDGFR-beta is directly correlated to proliferation indexes. Strong expression of VEGF and PDGFR-beta found in endothelium and tumor cells would seem to support a combined role in tumoral neoangiogenesis.

Adolescent↗
PubMedDate not supplied

[The evaluation of cell proliferation in gliomas].

INTRODUCTION: The homeostasis of tissues depends on a strict control of cell growth, differentiation and death. Several proteins, which are involved on the regulation of the cell cycle, can suffer diverse alterations and produce an uncontrolled cell proliferation and the genesis of a neoplastic process. The assessment of cell proliferation is an useful method applied to Neuro-oncology in order to know the behavior of gliomas. DEVELOPMENT: This work is focussed on the analysis of different methods, all of them employed to study the cell proliferation: immunostaining of proliferating cell nuclear antigen (PCNA) and Ki-67, DNA content and ploidy by flow cytometry, in vitro incorporation of bromodeoxyuridine (BrdU) and the identification of apoptotic cells. The study of the DNA by flow cytometry establishes a relationship between ploidy and the prognostic of gliomas. The assessment of PCNA provides us with objective data about the proliferative activity of gliomas. Both Ki-67 expression and BrdU incorporation are also useful methods in the study of gliomas. CONCLUSIONS: In short, the most malignant gliomas are characterized by a high frequency of aneuploidies and high PCNA, Ki-67 and BrdU labelling indexes. All of these described methods can be used as prognostic markers complementary to the classic criteria employed nowadays.

Apoptosis↗