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Biomedical subjects

R Prat

Publications and source records attributed to R Prat.

At least 19 recordsLinked to original sources
PubMed2003

[Multiseptated arachnoid cyst treated with fenestration after valvular insufficiency in an adult. ].

Treatment of symptomatic arachnoid cysts is based on two procedures: cyst fenestration versus derivation of CSF. Multiseptated cysts represent a very special group. We present the case of a 75 year old woman with a symptomatic multiseptated arachnoid cyst, developing subacute bleeding in one of the cavities. Final diagnosis was obtained after MRI. CSF derivation became insufficient with clear improvement after fenestration and communication to subarachnoid space.

Aged↗
PubMed2003

[Cauda syndrome due to spinal stenosis and diskytis in two different spinal levels. Diagnosis using myelo-TC].

We report a case of a 75 year old man presenting with paraparesis, urinary incontinence and saddle anesthesia evolving after several months and severe lumbalgia and bad general status which developed fewdays before admission. CT-scan showed spondilosis with lytic lesion at L5-S1 level. MR1 was not performed because the patient had a pacemaker. A myelo-CT study was performed showing a complete stop at L4-L5 level together with L5-S1 diskytis. Laminectomy of L5 and discectomy L5-S1 was performed obtaining tissue sample diagnostic of diskytis and osteomyelitis. Our patient had two lesions at two different levels with two independent syndromic appearence. Myelo-CT played an important diagnostic role in this case because MRI study could not be obtained.

Aged↗
PubMed1998

Failure of cerebral autoregulation in an experimental diffuse brain injury model.

The normal cerebral circulation has the ability to maintain a stable cerebral blood flow over a wide range of cerebral perfusion pressures and this is known as cerebral autoregulation. Autoregulation may be impaired in the injured brain. Closed head injury was induced in 28 Sprague-Dawley rats weighing 400-450 g. Four groups were studied: control and groups, head injured by weight drop from one meter height using 350 g, 400 g and 450 g respectively. CBF was monitored using laser-Doppler flowmetry along with monitoring of ICP and arterial blood pressure. If the correlation coefficient between CBF and CPP was > 0.85 and CPP was within normal range, loss of autoregulation was hypothesized. Loss of autoregulation was seen in all groups of injured rats during first four hours. A statistically significant difference (p = 0.041) was seen in the trequency of loss of autoregulation between injured and control animals. No loss of autoregulation was observed in the control group. In conclusion CBF and CPP provide information about loss of autoregulation in diffuse brain injury. Decrease in CBF and increase of ICP is observed as a result of loss of cerebral autoregulation. Knowledge of loss of autoregulation could help in the management of head injured patients.

Animals↗
PubMed1998

Prognostic factors in postraumatic severe diffuse brain injury.

UNLABELLED: It is usually defficult in clinical practice to establish factors affecting final outcome in patients suffering severe diffuse brain injury (SDBI), due to the absence of specific semiology. METHODS: We studied retrospectively 160 consecutive patients with criteria of SDBI. We performed a statistical analysis of epidemiological, clinical and radiological factors, and relationship with final outcome. RESULT: 35% of patients with severe head injury presented SDBI. Sixty percent were 15-35 year old and 73% male. More than 45% of the patients presented GCS 3 or 4. On CT performed during the first 24 h, haemorrhagic lesions appeared in white matter in 35% and subarachnoid haemorrhage was observed in 28%. During the first 24 h., 66% of patients presented values of intracranial pressure (ICP) above 20 mm Hg and a 33% below 20 mm Hg. Twenty percent of the patients had ICP > 20 mm and no response to treatment. According to the Glasgow Outcome Scale (GOS), mortality of more than 50% and 25% of patients with persistent vegetative state or severe disability were observed. CONCLUSIONS: Clinical evaluation, early CT findings, ICP values and their response to medical treatment and clinical complications were found to be related (p < 0.05) to final outcome (GOS).

Adolescent↗
PubMed1998

A differential response of diffuse brain injury on the concentrations of endothelin and nitric oxide in the plasma and brain regions in rats.

In the present study, we hypothesized that acute diffuse brain injury (DBI) in rats would produce an increase in endothelin-1 (ET-1), a potent vasoconstrictor, and/or nitric oxide (NO), a potent vasodilator, in plasma and brain areas in rats. DBI was induced in anesthetized male Sprague-Dawley rats (350-400 g) using a 350 g weight dropped from 1 meter height impact through a device designed by Marmarou et al., 1994. Blood plasma and brain tissue (cerebral cortex, diencephalon and brain stem) samples were collected for estimation of ET-1 and NO at zero or 6 h from rats (n = 6) subjected to DBI as well as control rats (n = 6), i.e., not subjected to DBI. In a separate group of animals, cerebral blood flow (CBF) was recorded at 0, 5, 10, 15, 30, 60, 120, 240 and 360 min after induction of DBI or sham-DBI. Acute DBI produced a significant decrease in CBF at 120 min after induction of DBI. Plasma levels of ET-1 was found to be significantly increased (from 0.89 +/- 0.09 to 2.09 +/- 0.29 pg ml-1), at 6 h following DBI. DBI produced a significant decrease in the levels of ET-1 in diencephalon (from 70.97 +/- 9.47 to 57.64 +/- 2.65 pg g-1). In contrast to ET-1, DBI produced a significant increase in the concentrations of NO in the diencephalon, cerebral cortex and brain stem at 6 h post DBI. It appears that DBI-induced increase in the levels of NO in brain regions which might be down regulating the synthesis of ET-1 in diencephalon. It is concluded that ET and NO homeostatic mechanisms may play a role in the regional and vascular responses associated with acute DBI.

Analysis of Variance↗
PubMed1998

[Analysis of prognostic factors in adults with chronic subdural hematoma].

The objective of the study is the analysis of prognostic factors observed in the evolution of 65 patients who presented chronic subdural hematoma surgically evacuated. Morbimortality ratio corresponding to our surgical technique is also presented. A retrospective statistical analysis of epidemiologic, clinic and radiologic factors was performed. Personal background of alcoholism or coagulopathy, decrease of the level of consciousness, a lower score at the Glasgow Coma Score, a maximum thickness of the hematoma superior to 2 cm, and the respiratory and neurologic complications were found to be related to a worst prognosis. Our surgical technique showed 4.6% of mortality and 1.5% of recurrence. Detection of prognostic factors may have important implications in the selection of patients for surgery. Our small craniectomy has similar clinical outcome than other surgical methods.

Age Distribution↗
PubMed1997

Pectin methylesterases from poplar cambium and inner bark: localization, properties and seasonal changes.

In the course of a study on the early events of cambial derivative differentiation in Populus x euramericana, seasonal changes in the pattern of pectin methylesterase (PME, EC 3.1.1.11) isoforms were followed. During the resting season, cell wall extracts contained mainly alkaline isoforms with an M(r) around 55 kDa and optimal pH between 5.6 and 6.0. Neutral isoforms with an M(r) around 35 kDa and optimal pH between 6.0 and 6.6 predominated in the extracts during the period of high meristematic activity. In the active cambial initials and in their immediate derivatives, the enzymes were immunolocalized exclusively in the dictyosomes. In older cells, they were present both in dictyosomes and in wall junctions. These results indicate that exportation of neutral PMEs towards the walls might be considered as an early marker of differentiation in cambial derivatives.

Carboxylic Ester Hydrolases↗
PubMed1997

Evaluation of cerebral autoregulation following diffuse brain injury in rats.

The normal cerebral circulation has the ability to maintain a stable cerebral blood flow over a wide range of cerebral perfusion pressures and this is known as cerebral autoregulation. This autoregulation may be impaired in the injured brain. Closed head injury was induced in 28 Sprague-Dawley rats weighing 400-450 g. Four groups were studied: control group, head injured rat from meter height using 350 g, 400 g and 450 g respectively. CBF, volume velocity was monitored using laser-Doppler flowmetry together with monitoring of ICP and arterial blood pressure. Correlation to assess the relationship between CBF and CPP was done in each animal every hour. If correlation coefficient was > 0.85 and CPP was within normal range, loss of autoregulation was hypothesized. Chi square test, ANOVA test and unpaired Student's t-test were done and significant level of p < 0.05 was established. Mean CBF in injured rats was significantly lower than controls (p = 0.028) at the fifth hour. CBV was lower in the group of 450 g 1 m impact than in controls at 3 h (p = 0.04). Velocity in the group of all injured rats, was significantly lower than in controls at 3 h (p = 0.032) and at 4 h (p = 0.027). Loss of autoregulation was seen during first four hours after trauma in all groups of rats who sustained injury. Statistical significant difference (p = 0.041) in loss of autoregulation between injured and control animals was seen. No loss of autoregulation was observed in the control group. In conclusion CBF and CPP provide information about loss of autoregulation in diffuse brain injury. Decrease in CBF and increase of ICP is observed as a result of loss of cerebral autoregulation. Knowledge of loss of autoregulation could give important information and help in the management of head injured patients.

Animals↗
PubMed1997

[Somatostatin receptors in meningioma: diagnostic and therapeutic value].

OBJECTIVE: We discuss the diagnostic and therapeutic usefulness of the presence of somatostatin receptors (SR) in meningiomas. DEVELOPMENT: The SR are membrane receptors, may be saturated, have great affinity and pharmacological specificity for somatostatin (SS) and its analogues. SR have been found in 100% of the meningiomas studied. The presence of a large number of SR in different tumours permits gammagraphic detection in vivo by marking SS analogues with 1-231-DTPA and subsequent visualization using a gamma camera. This study may help to differentiate between meningiomias and other tumour lines. Experiments using different SS analogues have shown different degrees of affinity of these SS analogues for the different receptors. In various animal models a potent inhibitor effect on tumour growth has been seen following SS and its analogues. Unlike in hypophyseal adenomas and endocrine gastro-entero-pancreatic tumours, neither SS nor its analogues have shown any direct inhibitory action on the growth of meningioma cell cultures. Quite the opposite occurs. A small but significant stimulation of growth was seen in the presence of SS. CONCLUSIONS: We consider the detection of SR by isotopic marking of SS analogues is useful in the differential diagnosis of meningiomas. The therapeutic usefulness of the analogues of SS for treatment of meningiomas remains controversial. Further study of the different types of receptors and analogues is necessary.

Antineoplastic Agents, Hormonal↗
PubMed1991

Structural features of the cell-wall polysaccharides of Asparagus officinalis seeds.

The fine structure of a beta-)1----4)-linked glucomannan from Asparagus officinalis has been determined by n.m.r. analysis of the oligosaccharides obtained by acidic and enzymic hydrolyses. Cleavage of the glucomannan with beta-D-mannase from Aspergillus niger and purification by h.p.l.c. gave oligosaccharide fractions that contained Man (mannose), GlcMan (beta-glucopyranosylmannose), Man2, Glc2Man, and Glc3Man as the major components. Simulated digestion of a polymer composed of randomly distributed monomers with the same Glc:Man ratio as glucomannan from A. officinalis led to the same polysaccharides. The random distribution of the monomers of glucomannan from A. officinalis was corroborated by the diffraction diagram of the raw flour, which indicated that the "in situ" glucomannan was amorphous, whereas both cellulose and mannans are crystalline.

Acids↗
PubMed1978

Gradient of Growth, Spontaneous Changes in Growth Rate and Response to Auxin of Excised Hypocotyl Segments of Phaseolus aureus.

Spontaneous growth was studied in excised mung bean (Phaseolus aureus Roxb.) hypocotyl segments. Measurements were made with a growth-recording apparatus using displacement transducers on single 5- to 6-millimeter samples excised from the growth zone immediately below the hook.Even for a given zone and under controlled experimental conditions, there are differences in the spontaneous growth of individual explants. Nevertheless, in every case, two phases of endogenous acceleration are found at 15 to 20 minutes, and 120 to 150 minutes after excision. Accelerations were separated by steady growth phases. Knowledge of the spontaneous growth curve appears important for the choice of the time of application of experimental stimuli. Auxin was added at various times after excision (0 to 6 hours). The classical biphasic response to auxin was obtained when the hormone was added during a steady phase of growth. However, the response was difficult to interpret when the hormone was added during an acceleration phase.Spontaneous and indoleacetic acid-induced growth were studied along the hypocotyl. Spontaneous growth rate and growth potential revealed by indoleacetic acid changed markedly along the growth gradient. The nature of spontaneous changes according to experimental time and state of differentiation of the cells is discussed.

Journal Article↗