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Biomedical subjects

I Berry

Publications and source records attributed to I Berry.

At least 73 records · Page 4Linked to original sources
PubMed1989

Histochemical characterization and functional significance of the hyperintense signal on MR images of the posterior pituitary.

MR imaging of the pituitary fossa characteristically shows a well-circumscribed area of high signal intensity in the posterior lobe on T1-weighted images. We used a combination of high-field MR, electron microscopy, and histologic techniques in experimental animals to determine whether the hyperintensity of the posterior lobe might be functionally related to hormone neurosecretory processes, and to attempt to establish its chemical nature. Histologic sections of a dog's pituitary gland processed with lipid-specific markers showed intense staining in the posterior lobe but not in the anterior lobe, thus documenting the location of fat in the posterior pituitary. Administration of vasoactive drugs known to influence vasopressin secretion to anesthetized cats produced changes in the volume of high-intensity signal in the posterior pituitary. Subsequent electron microscopy showed a significant increase in posterior lobe glial cell lipid droplets and neurosecretory granules in dehydration-stimulated cats. The data suggest that the pituitary hyperintensity represents intracellular lipid signal in the glial cell pituicytes of the posterior lobe or neurosecretory granules containing vasopressin. The volume of the signal may, in turn, reflect the functional state of hormonal release from the neurohypophysis.

Animals↗
PubMed1989

Magnetic resonance imaging and 31P magnetic resonance spectroscopy for evaluating focal cerebral ischemia.

Recent advances in magnetic resonance (MR) imaging and MR spectroscopy (MRS) allow the noninvasive in vivo study of a variety of anatomical, physiological, and biochemical alterations that may occur in different cerebral pathologies. The authors have investigated the use of MR imaging and MRS to monitor the evolution of experimental focal cerebral ischemia in rats. Permanent focal cerebral ischemia was induced in 36 rats, and 12 normal rats were used as a control group. Changes in high-energy phosphate metabolites were followed in vivo using MRS during the 1st hour and at 3 and 6 hours after ischemic insult. Changes in vivo MR images were evaluated at 1, 3, 6, 12, and 24 hours after ischemic insult. Significant decreases (p less than 0.05) in phosphocreatine/inorganic phosphate ratios and intracellular pH values occurred immediately after the induction of ischemia. The presence of an infarcted area seen on MR images was a constant finding at 3 hours after ischemic insult, and was well defined and localized at 12 and 24 hours. The location of areas of infarction seen on MR images correlated well with areas identified histopathologically. The T1 and T2 MR relaxation times were significantly increased 3 hours after ischemic insult and remained prolonged for at least 24 hours. The results show that MR imaging is a sensitive method to measure cerebral infarction, and that MRS is a sensitive measure of changes that occur in the early phases of ischemia, perhaps when cellular changes may still be reversible. At 3 and 6 hours after the ischemic insult, however, 31P-MRS spectra may appear to be "normal" despite the presence of well-documented areas of infarction.

Animals↗
PubMed1989

Epileptogenic cerebral vascular malformations and MRI.

The results of magnetic resonance imaging (MRI) performed in 67 patients with cerebral vascular malformations (35 arteriovenous malformations [AVM], 29 cryptic malformations, 11 venous angiomas and 2 associated lesions) were studied retrospectively after the patient population was divided into epileptics [25] and non-epileptics [42]. Several criteria were determined for each type of malformation in the two groups. They included patient's age, site of the malformation in relation to the cortex, size of the malformation, presence of a perilesional high-intensity signal on T2-weighted sequences and evidence of recent haemorrhage. Epileptogenic AVMs seemed to be more superficial and more often associated with a perilesional parenchymatous high-intensity signal on T2-weighted sequences than non-epileptogenic malformations. Epileptogenic cryptic malformations were closer to the cortex, larger, and specifically but rarely associated with changes in signal of the adjacent brain tissue on T2-weighted sequences. The few angiomas associated with epilepsy were, paradoxically, located in the cerebellum.

Adolescent↗
PubMed1988

High energy phosphate metabolism in experimental permanent focal cerebral ischemia: an in vivo 31P magnetic resonance spectroscopy study.

Relative levels of phosphate metabolites in the brain were examined in vivo by 31P magnetic resonance spectroscopy (MRS) in 50 Sprague-Dawley rats before, during, and after induction of focal permanent cerebral ischemia. After acquisition of baseline spectra, rats were subjected to injury within the core of the MR spectrometer, and 31P spectra were collected for 60 min after injury: in 7 rats, permanent, acute focal cerebral ischemia was induced (ischemia group); in 6 rats, mild hypoxia (FiO2 14%) was induced at the time of the ischemic insult and was maintained for 20 min (ischemia-hypoxia group); in 6 rats, mild hypoxia (FiO2 14%) only was induced for 20 min (hypoxia group). Control studies were performed in 25 rats. Cerebral intracellular pH, calculated from the chemical shift of inorganic phosphate (Pi), decreased immediately after injury in the ischemia and ischemia-hypoxia groups. The first 31P spectrum obtained after injury was characterized by an increase in Pi and a decrease in phosphocreatine (PCr) in the ischemia and ischemia-hypoxia groups; these changes in spectra were significantly greater in the ischemia-hypoxia group. No significant changes in adenosine triphosphate (ATP) were found in either group. Within 60 min of occlusion, 31P spectra returned toward baseline spectra in both ischemia-hypoxia and ischemia groups. No significant changes were seen in spectra of rats subjected to hypoxia alone. These results confirm that 31P MRS is a sensitive measure of early changes of high energy metabolites in focal cerebral ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

The effects of hypovolemic hypotension on high-energy phosphate metabolism of traumatized brain in rats.

To clarify the effect of hypovolemic hypotension on high-energy phosphate metabolism in head injury, sequential changes in in vivo phosphorus-31 magnetic resonance (31P MR) spectra were compared in 35 rats after impact injury with and without hypotension. Fourteen rats were subjected to hypotension alone (mean arterial blood pressure (MABP) of either 40 or 30 mm Hg for 60 minutes), seven to fluid-percussion impact injury (4 to 5 atm) alone, and 14 to impact injury and hypotension (MABP of 40 to 30 mm Hg). Impact injury alone caused a transient decrease in the phosphocreatine (PCr) level and an increase in the inorganic phosphate (Pi) value. While hypotension alone produced only small changes on 31P MR spectra, impact injury plus hypotension caused pronounced changes. Impact injury and an MABP of 40 mm Hg caused a 50% decrease in PCr concentration and an approximately twofold increase in Pi level, which were significantly greater than values in rats with impact injury alone. Impact injury and an MABP of 30 mm Hg also caused a significant decrease in adenosine triphosphate value, which was not observed in rats with impact injury alone or with an MABP of 30 mm Hg alone. Decreases in intracellular pH were greater in rats with impact injury and hypotension. After traumatic injury, the brain is extremely vulnerable to hypovolemic hypotension, as reflected in the loss of high-energy phosphates in brain.

Animals↗
PubMed1987

The utility of principal component analysis for the image display of brain lesions. A preliminary, comparative study.

Principal component analysis (PCA), a common tool from multivariate statistical analysis, has been implemented into the computer display system of a MR imaging device. PCA allows the calculation of images in which the information in a defined region of interest inherent in the basic acquired images is condensed. PCA image calculation has been applied to acquired MR studies of 13 patients with brain lesions. The appearance of the brain lesions on the resultant PCA images was scored in comparison to the acquired images before and after administration of Gd-DTPA as well as to other calculated images including T1, T2, hydrogen density, and contrast-optimized images. The conspicuity of a lesion and the number of distinguishable components within a lesion were slightly superior on PCA than on the acquired images. PCA is an analytical tool for MR imaging that should be helpful in revealing information that is inherent in, but not readily visible on, standard acquired MR images.

Brain Neoplasms↗
PubMed1987

The effect on human neuroblastoma spheroids of fractionated radiation regimes calculated to be equivalent for damage to late responding normal tissues.

Multicellular tumour spheroids (MTS) are a useful in vitro model of human cancer. An experiment was designed to assess the likely therapeutic advantage of hyperfractionation--a proposed strategy in radiotherapy. A cell line (NB1-G) derived from human neuroblastoma was grown as MTS. This MTS line is radiosensitive with low capacity for repair of sublethal radiation damage. These properties make NB1-G a suitable line to test the theoretical advantage of hyperfractionation. MTS were irradiated using alternative fractionated regimens, with fraction sizes varying from 0.5 to 4 Gy. In each experiment, the total dose was chosen to make the regimens theoretically isoeffective for damage to late-responding normal tissues (calculated using the linear-quadratic mathematical model with alpha/beta = 3 Gy). The radiation responses of MTS were evaluated using the end-points of regrowth delay and "proportion cured". Regimens using smaller doses per fraction were found to be markedly more effective in causing damage to neuroblastoma MTS, as assessed by either end-point. These experimental findings support the proposal that hyperfractionation should be a therapeutically advantageous strategy in the treatment of tumours whose radiobiological properties are similar to those of the MTS neuroblastoma line NB1-G.

Cell Line↗
PubMed1987

The effect of hypoxia on traumatic head injury in rats: alterations in neurologic function, brain edema, and cerebral blood flow.

We evaluated the effects of early posttraumatic hypoxia on neurologic function, magnetic resonance images (MRI), brain tissue specific gravities, and cerebral blood flow (CBF) in head-injured rats. By itself, an hypoxic insult (PaO2 40 mm Hg for 30 min) had little effect on any measure of cerebral function. After temporal fluid-percussion impact injury, however, hypoxia significantly increased morbidity. Of rats subjected to impact (4.9 +/- 0.3 atm) plus hypoxia, 71% had motor weakness contralateral to the impact side 24 h after injury, while only 29% of rats subjected to impact alone had demonstrable weakness (p less than 0.05). Lesions observed on MR images 24 h after injury were restricted to the impact site in rats with impact injury alone, but extensive areas with longer T1 relaxation times were observed throughout the ipsilateral cortex in rats with impact injury and hypoxic insult. Brain tissue specific gravity measurements indicated that much more widespread and severe edema developed in rats with impact injury and hypoxia. [14C]Iodoantipyrine autoradiography performed 24 h after injury showed that there was extensive hypoperfusion of the entire ipsilateral cortex in rats with impact injury and hypoxia. These results show that large areas of impact-injured brain are extremely vulnerable to secondary insults that can irreparably damage neural tissue, and provide experimental evidence for the observed adverse effects of hypoxia on outcome after human head injury.

Animals↗
PubMed1987

Edema and the lack of blood perfusion produce opposite effects on the magnetic resonance characteristics of acutely ischemic rat kidneys.

Both kidneys of 28 rats were studied with magnetic resonance imaging (0.35 tesla, double spin-echo technique with echo-delay times [TEs] of 28 and 56 ms and repetition times [TRs] of 0.5 and 2.0 seconds). Kidneys were studied before and up to 4 hours after ligation of the abdominal aorta above the origin of the left renal artery (20 rats) or after ligation of the left renal artery (eight rats). Any changes in the relaxation times of cortex and medulla and in the cortex-to-medulla contrast (CMC) were correlated to histologic data and renal water content. After the first hour following ligation of either the abdominal aorta or the left renal artery, the cortex of the left kidneys showed a 20% shortening of the mean T2 relaxation time (P less than .001), a 16% shortening of the mean T1 relaxation time (P less than .001), a 73% increase in mean CMC on T2-weighted images (P less than .001) and a 42% decrease in mean CMC on T1-weighted images (P less than .001). There were no significant changes either in relaxation times of the medulla of the left kidneys or in relaxation times and CMC of the right kidneys. During the next three hours, relaxation times of cortex and CMC remained unchanged in the rats with ligated abdominal aorta. In the rats with ligated renal artery, relaxation times of cortex and CMC returned to normal values.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1987

Posterior pituitary gland: appearance on MR images in normal and pathologic states.

T1-weighted magnetic resonance (MR) images of the pituitary gland and sella turcica routinely demonstrate a region of high signal intensity in the neurohypophysis. High-resolution MR imaging studies of the sella turcica in 200 subjects with a normal or abnormal sella were analyzed. The hyperintensity was found in the images of about 90% of healthy subjects and patients with microadenoma, in only 43% of patients with macroadenoma, and in 12% of patients with empty sellae. The signal was absent in several patients with functional or anatomic abnormalities of the hypothalamic-hypophyseal axis. It is concluded that the high signal intensity in the posterior lobe of the pituitary gland is present in most healthy individuals and that its absence in many patients with large intrasellar masses and empty sellae is due to compression of posterior lobe tissue. Its absence in diabetes insipidus further suggests a relationship between hyperintensity and the functional status of the hypothalamic-hypophyseal axis.

Adenoma↗
PubMed1986

Acute experimental cerebral ischemia: MR enhancement using Gd-DTPA.

The effects of a paramagnetic contrast agent, gadolinium-DTPA (Gd-DTPA), on magnetic resonance (MR) imaging of acute cerebral ischemia was investigated in a feline model of middle cerebral artery occlusion. Imaging was performed both before and after administration of an intravenous dose of 0.2 mmol/kg of Gd-DTPA. The animals were then sacrificed for pathologic correlation. No changes in intensity or relaxation times were noted before or after Gd-DTPA administration in two animals with 2 hours of occlusion. Infarcts were noted before and after contrast enhancement in all six cats with ischemia of greater than 16-hours duration. Gd-DTPA caused significant increase in intensity of infarct but not in that of normal cerebral tissue. Rapid enhancement was visible in infarcts of 16-24 hours, but such enhancement was slower in infarcts of 72-168 hours, presumably owing to slowed inflow caused by increased vasogenic edema in the latter group. Contrast enhancement of acute cerebral ischemic lesions with Gd-DTPA offers no improvement in sensitivity of MR imaging, although the conspicuity of the lesion may be improved. Additionally, contrast media may provide potential temporal and pathophysiological data for better characterization of cerebral ischemia.

Animals↗
PubMed1986

Gd-DTPA in clinical MR of the brain: 1. Intraaxial lesions.

Over 35 intraaxial lesions in 15 patients suspected of having intracranial tumors were studied with MR before and after injection of Gadolinium-DTPA (Gd-DTPA). Diseases included primary and metastatic brain tumors, plaques of multiple sclerosis, occult arteriovenous malformations, lymphoma, toxoplasmosis, and pituitary adenoma. The precontrast T2-weighted sequence (SE 2000/30, 60) was found to be most sensitive in detecting intraaxial lesions, showing 17 lesions that were not seen on the post-Gd-DTPA T1-weighted sequence (SE 500/30). In one case of multiple sclerosis, several lesions seen on the pre-Gd-DTPA study on T2-weighted images faded after injection of Gd-DTPA (due to T2 shortening). In two patients with large metastatic foci, other small metastatic lesions were seen better after Gd-DTPA on both T1- and T2-weighted sequences. Four other patients with only one focal-enhancing lesion and one patient with multifocal lesions on T1-weighted images actually had a much larger single glioma depicted on pre-Gd-DTPA T2-weighted images. In a patient with AIDS, a ring-enhancing lesion thought to be an abscess proved to be lymphoma. The cryptic arteriovenous malformations enhanced but showed more characteristic findings, such as hemorrhage, on pre-Gd-DTPA studies. Our experience suggests that Gd-DTPA may not improve sensitivity of MR in the detection of intraaxial lesions. However, functional aspects of brain disease, such as the presence of perfusion of a lesion and active breach of the blood-brain barrier, are depicted well with Gd-DTPA and are vital for proper diagnosis in many instances.

Adult↗
PubMed1986

Gd-DTPA in clinical MR of the brain: 2. Extraaxial lesions and normal structures.

Fifteen patients with suspected extraaxial tumors were evaluated with MR before and after intravenous injection of Gadolinium-DTPA (Gd-DTPA). Meningiomas (7), neurinomas (4), chordomas (2), a previously irradiated dural metastasis, and a giant aneurysm were studied. All the lesions except the dural metastasis enhanced. In two patients with asymptomatic meningiomas, the use of Gd-DTPA with MR allowed definitive diagnosis of the lesions when the routine MR did not. Gd-DTPA also provided improved definition of intracranial tumor margins, produced differential enhancement of dura and nasopharyngeal mucosa from tumor, and caused enhancement of the choroid plexus, some venous structures, the pituitary gland, and its stalk. The enhancement of the pituitary suggests a role for Gd-DTPA in the diagnosis of microadenomas. Routine T2-weighted images without Gd-DTPA were useful in differentiating neurinomas from meningiomas. Judicious use of Gd-DTPA should improve the ability of MR to detect extraaxial lesions, delineate their extent, and characterize their perfusion.

Aged↗
PubMed1986

Combined magnetic resonance imaging and spectroscopy in experimental regional injury of the brain. Ischemia and impact trauma.

Combined magnetic resonance imaging (MRI) and spectroscopy (MRS) allows unique experimental insights into the central nervous system (CNS) disorders. Clinical applications are forthcoming. In order to address the potential clinical uses of MRI/MRS, experimentally induced focal brain lesions were evaluated with this modality. Focal lesions more closely mirror clinical situations than do global insults, but have rarely been the focus of MRS studies. Fluid-percussion trauma in 48 rats, focal ischemia in 18 rats and in 16 mongrel dogs were produced, with various degrees of severity. A discrepancy between temporal evolution data of MRI and MRS was found: MRI always showed an increase in lesion extension over time while 31P and 1H MRS almost always showed improvement. The severity and evolution of these MRS findings was surprising, and differed from the results reported for global brain injuries. Besides possibly reflecting real improvement in the metabolic state, other explanations for the phenomena exist. Diffusion of inorganic phosphate out of the regional site of injury and its reincorporation for more prominent lactate build-up in regional injury are possible. Therefore the use of MRS to predict metabolic and clinical outcomes of regional brain injury requires methodologic caution, but its combination to MRI offers an unprecedented tool for studies of focal CNS pathology.

Animals↗
PubMed1986

Magnetic resonance imaging in the evaluation of nimodipine-treated acute experimental focal cerebral ischemia.

We evaluated the sensitivity of magnetic resonance (MR) imaging in documenting effects of nimodipine in experimental focal cerebral ischemia. Twenty-five Sprague Dawley rats underwent unilateral occlusion of the middle cerebral artery and were imaged at different intervals thereafter. Neuropathologic and neurologic data were correlated with MR imaging results. Compared with controls, nimodipine-treated rats showed a significantly smaller infarct size (p less than 0.001), as documented by MR imaging and confirmed by neuropathologic evaluations. A less intense signal on the T2 weighted sequence was found in nimodipine-treated rats in basal ganglia (p less than 0.001) and cortex (p less than 0.05). MR imaging may afford unprecedented diagnostic sensitivity in assessing pharmacologic efficacy in cerebral ischemia.

Animals↗
PubMed1986

Combined magnetic resonance imaging and bihemispheric magnetic resonance spectroscopy in acute experimental focal cerebral ischemia.

Combined magnetic resonance imaging (MRI) and 31P-magnetic resonance spectroscopy (MRS) were employed to evaluate acute regional cerebral ischemia in cats following middle cerebral artery occlusion (MCAO). MRI changes were first reliable 3 hours after MCAO; progressive increases in T1 and T2 relaxation times were noted for 12 hours after MCAO. Immediately after MCAO, 31P-MRS revealed decreased phosphocreatine (PCr) and increased inorganic phosphate (Pi); the PCr/Pi ratio fell from 2.23 +/- 0.40 to 0.68 +/- 0.04 (p less than 0.005). This relative decrease in high energy phosphates improved significantly by 3-5 hours after MCAO (0.67 +/- 0.04 versus 1.00 +/- 0.03, p less than 0.001). By 12 hours, the ratio had increased by 27 per cent. The dissociation between the progressive MRI changes and the gradual improvement in 31P-MRS suggests a difference between the processes affecting proton distribution and phosphate metabolism in acute regional ischemia.

Acute Disease↗
PubMed1986

Gadolinium-DTPA in the magnetic resonance evaluation of the postoperative patient. Work in progress.

The application of gadolinium-DTPA to magnetic resonance scanning has been demonstrated to have considerable potential. Because the evaluation of the post-operative patient is particularly difficult for magnetic resonance due to the non-specific appearance of surgical trauma and edema, we attempted to formulate some preliminary impressions regarding the use of gadolinium-DTPA in this setting based on our experience with 15 patients studied at varying intervals following surgery, from 2 days to 8 years. Specifically, the time course and appearance of normal post-surgical enhancement was found to exhibit certain patterns. Recognition of these patterns may allow differentiation from pathology and may result in gadolinium-DTPA adding useful information in evaluating these patients.

Adult↗