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Biomedical subjects

S B Berger

Publications and source records attributed to S B Berger.

16 recordsLinked to original sources
PubMed1998

Frameless laser-guided stereotaxis: A system for CT-monitored neurosurgical interventions.

OBJECTIVE: Since a simple, rapid and accurate stereotactic system allowing CT monitoring would offer the neurosurgeon several advantages, the feasibility and application accuracy of frameless laser-guided freehand point stereotaxis for neurosurgical interventions was studied. METHODS: A Cartesian coordinate grid mounted upon the far wall of a CT scan room defined a plane. The scanner isocenter defined the origin of a three-dimensional coordinate system. Phantom entry point and target point coordinates were determined by the positional CT cursor. These coordinates were entered into a computer which determined the coordinates of the grid intersection point with a line passing through the entry and target points. A tripod-mounted laser assembly comprising two encased lasers oriented retrograde and antegrade along opposite vectors, was positioned near the grid. The retrograde laser was positioned to illuminate the marked grid intersection point while the antegrade laser simultaneously illuminated the entry point; the beams were thereby aligned along the line of trajectory. The tip of a probe was placed on the entry point; the hub was then moved into the path of the antegrade laser, thereby aligning the probe with the line of trajectory. The probe was then inserted to the target at a trigonometrically calculated distance. RESULTS: Ten consecutive phantom tests averaged 17.5 min. Phantom test application accuracy averaged +/-2 mm at an average insertion distance of 7.1 cm. CONCLUSION: Phantom tests indicate that simple, rapid and accurate CT-monitored frameless laser-guided freehand point stereotaxis is feasible. Clinical investigation is warranted.

Humans↗
PubMed1998

Inflammatory disease of the jaw: appearance on reformatted CT scans.

OBJECTIVE: Before the development of dental CT reformatting software, much of the radiographic assessment of the mandible and maxilla was performed in the dentist's office using plain radiographs. The widespread use of dental reformatting software, however, has caused the radiologist to take a more active role in evaluating the jaw. Unfortunately, most radiologists have had little experience in this area, and many of the CT findings are undescribed. Our objective, therefore, was to determine the CT appearance of dental-related inflammatory disease of the jaw and to discuss the mechanisms causing such disease. MATERIALS AND METHODS: Reformatted CT scans of 400 patients referred for dental implant assessment were evaluated for abnormalities related to infection of dental origin, inflammation of dental origin, or both. The diagnosis was confirmed by surgery, clinical presentation, classic plain film appearance, or a combination of the three. RESULTS: The following disease processes were identified and described: periodontal lesions, periapical lesions, condensing osteitis, disuse bone atrophy associated with edentia, and maxillary sinus abnormalities associated with dental disease. CONCLUSION: Inflammatory diseases of the jaw and their sequelae are frequently seen on CT scans of patients referred for examination before dental implantation. Because radiologists now take an active role in evaluating the jaw, they need to become familiar with these findings.

Adult↗
PubMed1996

Medical-legal issues in teleradiology.

With the advent of high-speed, high-resolution digital imaging and network transmission, teleradiology promises to dramatically change the mechanism for interpreting radiologic images and the traditional relationships between radiologists and patients and referring physicians. We discuss the current status of medical-legal issues pertaining to privacy, licensing, credentialing, liability, and fraud for teleradiology. Special emphasis is placed on the technical factors that may result in differences in image properties, consequently affect radiologic diagnosis, and bring the potential for liability.

Confidentiality↗
PubMed1995

Supercomputer algorithms for efficient linear octree encoding of three-dimensional brain images.

We designed and implemented algorithms for three-dimensional (3-D) reconstruction of brain images from serial sections using two important supercomputer architectures, vector and parallel. These architectures were represented by the Cray YMP and Connection Machine CM-2, respectively. The programs operated on linear octree representations of the brain data sets, and achieved 500-800 times acceleration when compared with a conventional laboratory workstation. As the need for higher resolution data sets increases, supercomputer algorithms may offer a means of performing 3-D reconstruction well above current experimental limits.

Algorithms↗
PubMed1995

Oral-maxillary sinus fistula (oroantral fistula): clinical features and findings on multiplanar CT.

OBJECTIVE: Oroantral fistula, an abnormal communication between the oral cavity and the maxillary sinus, is infrequently diagnosed radiologically. The purpose of this study was to describe the CT findings and clinical features of oroantral fistula and to show that dental CT multiplanar reformatting programs can be instrumental in diagnosing this condition. SUBJECTS AND METHODS: The study included eight patients with clinically confirmed oroantral fistula or with radiologic evidence of oroantral fistula. Fistula size, degree of alveolar atrophy, nature of maxillary sinus disease, and related dental disease were assessed along with the clinical presentations. RESULTS: The most frequent CT findings were bony discontinuity of the maxillary sinus floor, communication between the oral cavity and the sinus, soft-tissue opacification of the ipsilateral maxillary sinus, focal areas of alveolar atrophy, and associated periodontal disease. In 6 of 8 patients there was 100% opacification of the ipsilateral maxillary sinus, and in 5 of 8 patients the contralateral sinus appeared completely normal. The fistula size ranged from 13.5 mm2 to 189 mm2. CONCLUSION: The appearance of oroantral fistula on multiplanar CT imaging is disruption of the bony floor of the maxillary sinus with soft-tissue opacification of the ipsilateral sinus. Dental reformatted CT can be useful for evaluating patients suspected of having oroantral fistula, and this condition may be found incidentally in patients referred for evaluation for osseointegrated root-form dental implants.

Adult↗
PubMed1994

Duplicate cervix and vagina associated with infertility, endometriosis, and chronic pelvic pain.

BACKGROUND: Müllerian anomalies are associated with several gynecologic complications including endometriosis, infertility, and pelvic pain. CASE: A woman with duplicate cervix and a non-communicating longitudinal vaginal septum, but no other uterine anomalies, presented with pelvic pain, secondary infertility, and a long history of endometriosis. She was treated with operative laparoscopy and excision of the vaginal septum. CONCLUSION: A thorough evaluation, including history, physical examination, and appropriate imaging techniques (hysterosalpingography and magnetic resonance imaging) facilitates accurate diagnosis of anatomical defects and any associated disease in cases of unusual müllerian anomalies. An accurate preoperative diagnosis allows a planned, efficient surgical approach.

Abnormalities, Multiple↗
PubMed1992

Inhibition of nitric oxide synthesis increases focal ischemic infarction in rat.

We investigated whether inhibition of nitric oxide (NO) biosynthesis with N-omega-nitro-L-arginine (NNA), a competitive inhibitor of NO synthase (NOS), would modify the volume of the focal ischemic infarction produced by occlusion of the middle cerebral artery (MCA) in spontaneously hypertensive rats. NNA was infused for 1 h (2.4 mg/kg/h) immediately following occlusion of the MCA. NNA increased lesion volume 24 h later by 32% over controls (150.8 +/- 16.6 to 199.2 +/- 17.4 mm3; p less than 0.001, n = 6). This effect was antagonized by co-infusion of L- but not D-arginine. The antihypertensive rilmenidine (0.75 mg/kg) reduced the lesion by 27% (p less than 0.05, n = 4). Changes in lesion size were confined to the penumbra. NNA increased arterial pressure (AP) (118 +/- 8.9 to 149 +/- 16.0 mm Hg; p less than 0.01, n = 3) but did not change regional CBF. However, elevation of AP did not change the lesion volume or distribution. We conclude that inhibition of the constitutive form of NOS in vivo increases the volume of focal ischemic infarction as a consequence of reduced NO biosynthesis. The absence of NO availability may extend lesion formation by inhibition of reactive hyperemia, platelet disaggregation, and/or release of neuroprotective neuromodulators in the penumbra, which may counteract and override any of its neurotoxic actions.

Amino Acid Oxidoreductases↗
PubMed1992

Reduction in focal cerebral ischemia by agents acting at imidazole receptors.

Treatment with the alpha 2-adrenergic antagonist idazoxan (IDA) can provide protection from global cerebral ischemia. However, IDA also recognizes another class of receptors, termed imidazole (IM) receptors, which differ from alpha 2-adrenergic receptors and are responsible for the hypotensive actions of some centrally acting agents such as the oxazole rilmenidine (RIL). We therefore sought to determine whether RIL, an agent highly selective for IM receptors, offered protection from focal cerebral ischemia elicited in rat by ligation of the middle cerebral artery (MCA). We compared the effects of RIL with the effects of IDA and the selective non-IM alpha 2-antagonist SKF 86466 (SKF). In addition, we examined whether the neuroprotective effects of RIL and IDA could be attributed to changes in local CBF (LCBF). The MCA was occluded and animals either received immediate administration of drug while arterial pressure was maintained for 1 h or had local CBF increased to 200% of control for 1 h by hypercapnia or hypertension. RIL elicited a significant dose-dependent preservation of tissue to 33% of control at optimal dose (0.75 mg/kg). IDA (3 mg/kg) significantly reduced the size of ischemic infarction by 22%. In contrast, SKF (15 mg/kg) as well as doubling of LCBF did not preserve ischemic tissue. We conclude that both RIL and IDA can reduce focal ischemic infarction but that the mechanism does not appear secondary to antagonism of alpha 2-adrenergic receptors or elevation of LCBF. Occupation of IM receptors, either in the ischemic zone or at remote brain sites, may be responsible for neuroprotection of RIL and IDA.

Adrenergic alpha-Agonists↗
PubMed1991

Receptor-selective analogs demonstrate NPY/PYY receptor heterogeneity in rat brain.

Neuropeptide Y (NPY) receptors are heterogeneous, consisting of at least two subclasses, Y1 and Y2. We sought evidence for differential expression of NPY receptor subtypes in the rat brain. Tissue was incubated with 125I-peptide YY (PYY) which labels NPY and PYY binding sites. The Y1-selective agonist, p[Pro34]NPY, and the Y2-selective agonist, pNPY 13-36, were used as displacing ligands. Autoradiographic analyses of regional receptor binding demonstrated heterogeneity across brain regions. We conclude that Y1- and Y2-receptors may be independently expressed in the brain. While the predominate NPY/PYY receptor subtype in the brain is Y2, there are also Y1-receptors in some brain regions such as the superficial layers of the parietal cortex.

Animals↗
PubMed1991

Electrical stimulation of cerebellar fastigial nucleus reduces ischemic infarction elicited by middle cerebral artery occlusion in rat.

Electrical stimulation of the cerebellar fastigial nucleus (FN) globally and profoundly increases cerebral blood flow via a cholinergic mechanism. In cerebral cortex, the vasodilation is unassociated with alterations in cerebral glucose utilization, a condition favoring protection against cerebral ischemia. We sought to determine whether FN stimulation would modify the size of the focal ischemic infarction resulting from occlusion of the middle cerebral artery (MCA). The MCA was occluded in anesthetized rats of the spontaneously hypertensive (SHR) or Sprague-Dawley (SD) strains with or without 1 h of electrical stimulation of the FN. Twenty-four hours later, rats were killed and the volume of the infarction established in thionin-stained sections. in SHRs, FN stimulation reduced by 40% the well-established cortical and partially subcortical infarctions elicited by occlusion of the MCA (from 186 +/- 35.2 to 113 +/- 47.1 mm3, mean +/- SD, n = 15; p less than 0.001). The zone of retrieval was anatomically constant, consisting of a rim of cortex dorsal and ventral to the infarction and medially within the thalamus and striatum corresponding to the penumbral zone described by others. The effect was comparable in rats of the SD strain having smaller infarctions. The effect of FN stimulation appears to be selective for the FN system in that it is not evoked by stimulation of the dentate nucleus and is blocked by systemic administration of atropine (1.0 mg/kg). We conclude that excitation of an intrinsic system in brain represented in the rostral FN has the capacity to reduce substantially an ischemic infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Magnetic resonance imaging demonstrates that electric stimulation of cerebellar fastigial nucleus reduces cerebral infarction in rats.

We sought to determine whether high spatial resolution magnetic resonance imaging is useful for noninvasive quantitation of the ischemic infarct produced by occlusion of the middle cerebral artery and for detection of reduced infarct volume elicited by electric stimulation of the cerebellar fastigial nucleus. Male rats of the spontaneously hypertensive strain were anesthetized, the middle cerebral artery was occluded, and the fastigial nucleus was stimulated for 1 hour. Twenty-four hours later, rats were reanesthetized and T1- and T2-weighted images were obtained. Rats were killed and the volume and distribution of the lesion was established by histopathology. Magnetic resonance imaging estimates of the lesion volume were 271 +/- 41.0 mm3 (middle cerebral artery, n = 5) and 148 +/- 8.4 mm3 (middle cerebral artery + fastigial nucleus stimulation, n = 6; 45% reduction, p less than 0.05). Histopathological analysis revealed a lesion of 229.8 +/- 15.4 mm3 involving somatosensory cortex, lateral caudate putamen, and lateral hippocampus. Fastigial nucleus stimulation resulted in a 36% reduction in infarct volume to 146.0 +/- 10.3 mm3. The retrieved zone was largely in the cortex dorsal and ventral to the lesion and mostly posterior to the lesion. The estimates of lesion volume by magnetic resonance imaging and histopathology did not differ and were highly correlated (r = 0.90; p less than 0.001). This study confirms our previous finding that fastigial nucleus stimulation reduces the volume of a focal ischemic infarct and demonstrates that magnetic resonance imaging not only accurately estimates the volume of the lesion but also can detect changes as small as 50-100 mm3.

Animals↗
PubMed1987

Glial glutamate dehydrogenase: ultrastructural localization and regional distribution in relation to the mitochondrial enzyme, cytochrome oxidase.

Glutamate dehydrogenase (GDH) is primarily a mitochondrial enzyme involved in the metabolism of glutamate. We have recently shown by light microscopic immunocytochemistry that, within detergent-permeabilized brain tissue, GDH is enriched in glial cells, particularly in regions utilizing L-glutamate as a neurotransmitter. In this study, we used immunogold labeling to quantitatively establish that the form of the enzyme recognized by the presently used GDH antiserum is associated primarily with a subpopulation of mitochondria in ultrathin, plastic-embedded sections of the rat cortex and striatum. Permeabilization with detergents was omitted in these studies, so as to preserve the ultrastructure. As expected, labeled mitochondria occurred both in neurons and glia. Furthermore, light microscopic comparisons of the regional distributions of peroxidase immunoreactivity for GDH and a histochemical reaction product for a second mitochondrial enzyme, cytochrome oxidase (CO), were used to demonstrate that high levels of GDH in glia of glutamate-receptive areas do not necessarily reflect the areas' demand for elevated oxidative metabolism. While all regions showing intense labeling for glial GDH also exhibited high levels of CO activity, many additional regions showing high levels of CO activity contained no detectable immunoreactivity for glial GDH. These light-microscopic comparisons reveal that the energy requirements are not the only factors accounting for the regional heterogeneity of the enzyme. We conclude that glial mitochondria are heterogeneous with respect to their GDH content and that GDH is enriched in areas exhibiting chronically active glutamatergic transmission.

Animals↗