Biomedical subjects
Publications and source records attributed to J M Weinstein.
We describe a patient with an unusual coronary anatomic variant in which the heart was supplied by a single coronary artery arising above the left sinus of Valsalva.
This is the first reported case of a coronary artery anomaly in which the left circumflex artery was absent. The lateral and posterior aspects of the left ventricle were supplied by a large diagonal artery and a very long right coronary artery which continued along the atrioventricular groove.
PURPOSE: It has been shown previously that the sera, from patients with visual paraneoplastic syndrome associated with lung cancer, contain immunoglobulins that are reactive with the tumor and with photoreceptor and large retinal ganglion cells. The purpose of this study is to determine the retinal cell population that reacts with immunoglobulins in the sera of patients with melanoma-associated retinopathy. METHODS: Clinical and electrophysiologic studies were used to determine the locus responsible for the visual defect in each patient. Sera from two patients with melanoma-associated retinopathy, from a patient with herpes zoster, and from a patient who had a colon tumor were obtained. The sera were incubated with sections of retina obtained from a healthy 3-year-old child who had died of asphyxiation. The tissue sections subsequently were incubated with biotin-labeled anti-human immunoglobulin G, and then with streptavidin-labeled peroxidase. Finally, the tissue sections were developed to show peroxidase activity in the targeted retinal cells. RESULTS: Clinical and electrophysiologic studies were consistent with a defect in intra-retinal transmission distal to the photoreceptors. The immunoglobulins from the patients with the melanoma-associated retinopathy reacted selectively with the bipolar cells of the retina; approximately 30% of the bipolar cells were immunoreactive. The sera from the other two patients were not reactive with any of the retinal cells examined. CONCLUSIONS: The sera of patients with the paraneoplastic syndrome, melanoma-associated retinopathy, contain high titer immunoglobulins that are reactive only with a subset of the bipolar retinal cells. The clinical, electrophysiologic, and immunologic studies are all consistent with an intra-retinal transmission defect at the level of the bipolar cells.
In order to assess early changes in heart rate variability, we studied 81 patients with acute myocardial infarction during the initial 24 hours after thrombolytic therapy. The standard deviation of the mean heart rate and the low (0 to 0.05 Hz), mid (0.05 to 0.20 Hz), and high (0.20 to 0.35 Hz) frequency band power were evaluated with 24-hour ECG Holter recordings. We found diminished variance in the time domain and reduced power spectrum in the frequency domain compared with a group of 41 normal subjects (p < 0.01). Patients with anterior infarction had significantly (p < 0.01) higher heart rates and lower heart rate variability values than patients with inferior infarction. Reduction in heart rate variability occurred within the first 8 hours in patients with anterior infarction; a significant fall (p < 0.03) was especially noted in the high-frequency band after a decline in ST-segment elevation. Heart rate variability alterations in patients with inferior infarction were most evident in the final 8-hour interval. These findings may be viewed in terms of sympathovagal imbalance and may be related to clinical signs of intense autonomic nervous system activity that are observed early in the course of acute anterior and inferior myocardial infarction.
The purpose of the study was to determine the efficacy of furosemide in addition to intravenous fluids in the prevention of radiocontrast nephropathy. 18 patients, referred to a radiocontrast study, considered at risk because of preexisting renal insufficiency, were enrolled in a prospective, randomized, controlled trial, performed at the secondary care center of a 1,100-bed private university hospital. In addition to fluids, the treatment group received furosemide (mean dose 110 mg) intravenously 30 min prior to the injection of contrast material. The control group received fluids (mean 3 liters). Radiological studies were mostly angiographies performed with both ionic and non-ionic contrast material, at an average dose of 245 ml. Renal function significantly deteriorated in the group pretreated with furosemide (p < 0.005 by ANOVA), with a rise in serum creatinine from 145 +/- 13 to 182 +/- 16 mumol/l at 24 h, while no change occurred in the control group (from 141 +/- 6 to 142 +/- 7 mumol/l). Renal failure was associated with weight loss in the furosemide-treated group. Furosemide may be deleterious in the prevention of radiocontrast nephropathy.
This study examined the behavior of the presaccadic spike potential (SP) in 20 normal, right-handed subjects for self-paced 10 degree saccades along vertical, horizontal and oblique meridians. The SP was recorded differentially between posterior parietal sites and a linked ear reference. The SP amplitude showed clear directional tuning properties with the maximum response prior to saccades directed in an oblique, downward and contralateral direction. The minimum response was obtained for upward saccades. The data were fitted to a model consisting of 3 components: (1) a constant component reflecting saccadic amplitude; (2) a component with narrow directional tuning that is modeled from properties of frontal eye field neurons in monkeys; and (3) a component with broad directional tuning that is designed to reflect directional tuning properties of potentials originating from horizontal and vertical saccade generators, motoneurons and extraocular muscles. The narrowly tuned mechanism is sufficient to encode the direction of saccades. One surprising finding, though, was that the broadly tuned mechanism was necessary and sufficient to account for differences in SP amplitude as a function of electrode laterality. Application of this model approach to published data for periorbital SP, recorded between periorbital and parietal sites (G. W. Thickbroom and F. L. Mastaglia, Electroencephalogr. Clin. Neurophysiol., 64 (1986) 211-214), suggested that this potential represents a broadly tuned mechanism with directional tuning opposite the parietal SP. These data indicate that the periorbital and parietal SPs represent activation of different networks of central generators.
The group of six patients in this study experienced delayed visual loss following head trauma. Visual loss occurred from 1 day to 13 years after the initial injury. All patients suffered indirect trauma to the internal carotid artery resulting in formation of either an aneurysm or pseudoaneurysm or a carotid-cavernous fistula. Review of the radiologic and clinical findings was performed in six patients. The diagnosis was established by computed tomography, magnetic resonance imaging, and angiography. All patients had follow-up clinical evaluation and imaging studies. Treatment by neurosurgical or interventional neuroradiologic procedures resulted in significant visual improvement in five patients. Different pathophysiologic mechanisms could be correlated with the delayed visual loss produced by the two types of lesions. The pathologic changes associated with the aneurysms/pseudoaneurysms included direct compression of optic nerves and/or chiasm and intracranial hematoma. A carotid-cavernous fistula caused delayed visual loss by either hematoma at the orbital apex or compression of the chiasm and/or optic nerves by saccular dilatation of the cavernous sinus. The delayed onset of decreased vision following head trauma should alert the physician to the possibility of a traumatic aneurysm/pseudoaneurysm or a carotid-cavernous fistula. Different neuro-ophthalmologic symptoms can usually be correlated with the pathologic changes demonstrated by neuroimaging procedures.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Electroencephalographic (EEG) activity associated with voluntary and spontaneous saccades were analyzed in 12 normal subjects to determine the influence of volition upon the presaccadic spike potentials (SPs). In addition, two different electrode configurations, of a temporal and a parietal derivation, and two different filter bandwidths were simultaneously analyzed to clarify issues regarding the structure, function, and origin of SPs. An off-line averaging of the pre- and postsaccadic EEG epochs showed distinct spike potentials associated with spontaneous saccades in both the temporal and the parietal locations. Subsequent statistical analyses indicated that the amplitude of the SPs associated with spontaneous saccades was not significantly different from the respective amplitude of SPs preceding voluntary saccades. Independent effects of filter bandwidth and electrode derivation are suggestive of a complex late presaccadic EEG activity.
A 35-year-old woman with metastatic breast cancer experienced acute monocular visual loss. Her fundus examination was normal. The patient died 48 h later, and autopsy demonstrated hematogenously disseminated aspergillosis. The retrobulbar optic nerve of the affected eye showed infarction due to massive embolization with Aspergillus fumigatus. Although the retrobulbar optic nerve is relatively resistant to ischemia, its meningeal derived blood supply may be occluded by massive showers of emboli.
Acute multifocal posterior placoid pigment epitheliopathy (APMPPE) is an unusual self-limited retinal disorder that has been associated with various systemic complications. To our knowledge, three prior cases associated with cerebral vasculitis have been described. This article describes a patient with APMPPE and angiographically documented cerebral vasculitis who was notable because of (a) the presence of two different cerebral ischemic events, occurring 1 month apart, and (b) the long latency (3 months) between the onset of ocular symptoms and the second cerebral ischemic event. Recognition of the association between APMPPE and cerebral vasculitis may permit early treatment of CNS involvement and prevention of morbidity.
Computerized tomography scan evidence of periosteal elevation in patients with orbital cellulitis is interpreted in the current medical literature as an indication of subperiosteal abscess. We present three such cases in which surgical drainage yielded clear fluid or granulation tissue rather than pus. A fourth case resolved on antibiotic therapy alone. Cases of periosteal elevation that resolve without surgery may represent inflammatory effusion, infections of lesser virulence, or propagation of granulation tissue rather than true abscesses. We suggest that periosteal elevation seen in patients with orbital cellulitis should represent a relative rather than an absolute indication for drainage surgery.
Acute left homonymous hemianopia and recurrent scintillating scotoma occurred in a 43-year-old woman due to metastases from a cutaneous malignant melanoma that had been resected 5 years previously. Computed tomography initially demonstrated small, probably embolic, areas of occipital lobe infarction. Five months after the onset of her visual symptoms, massive cerebral hemorrhage occurred from a large right occipital lobe tumor that had not been present initially. Autopsy demonstrated malignant melanoma. Visual symptoms related to tumor embolization and/or cerebral hemorrhage may be the presenting features of metastatic cutaneous malignant melanoma.
Presaccadic potentials in humans consist of 3 components, a slow negative shift, a positive antecedent potential and a spike potential (SP). This study demonstrated the presence of the SP before another class of rapid eye movements, fast phases of optokinetic nystagmus (OKN), in 11 right-handed, normal human subjects and compared the amplitude of the averaged SP for OKN fast phases, recorded at P3 and P4 (International 10/20 System), with the SP amplitude for 10 degrees self-paced saccades between two red light-emitting diodes. In particular, the effects of electrode laterality, rapid eye movement direction and two sets of instructions during the OKN task were assessed. Subjects were told to either 'look at the screen' (OKN1 paradigm) or to 'try to slow or stop the motion of the pattern' (OKN2 paradigm) during presentation of optokinetic stimulation. As in the case of saccades, the OKN fast phase velocity spike was used to trigger the signal averager (Nicolet (CA-1000]. There were two significant differences in SP amplitude prior to saccades and OKN fast phases. First, 3-way analysis of variance (ANOVA) and Newman-Keuls comparisons revealed that the SP was attenuated significantly for OKN for either eye movement direction over either left or right recording sites (F = 16.045, P less than 0.001). This effect was not related to amplitude differences in eye movements in the different tasks, although a contribution of variance in the OKN fast phase amplitudes cannot be excluded.(ABSTRACT TRUNCATED AT 250 WORDS)
Three components of pre-saccadic evoked potentials have been identified in humans: a slow negative shift (SNS), a positive antecedent potential (AP) and a spike potential (SP). This study examined the influences of: instructions to the subject to make saccades; the presence of a visual target; and the direction of the saccades on the amplitude of the averaged SP, which was recorded from P3 and P4 (International 10/20 System) in 20 normal, right-handed subjects. Recordings were made for spontaneous saccades prior to receiving instructions in six subjects. Twenty subjects performed self-paced saccades in the presence of a 10 degrees visual target (two red LEDs) and while blindfolded in a dark room. The SP was either absent or grossly altered (broadened) for spontaneous saccades in an illuminated room; it was robust for self-paced saccades in light or darkness. Three-way analysis of variance revealed a highly significant cortical laterality (P3 vs P4) X saccade direction interaction (P less than 0.001), reflecting that for a given saccade direction, the SP was larger over the contralateral recording site for the self-paced light (SPL) paradigm (Newman-Keuls test). In the self-paced dark (SPD) paradigm, though, this was only true for saccades to the right. By contrast, scatter plots of the directional indices (D.I. = [(SP for contralateral) - (SP for ipsilateral)]/[(SP for contralateral) + (SP for ipsilateral saccades)] for left (P3) and right (P4) recording sites from individual subjects revealed a significant negative correlation for both SPL (r = 0.78) and SPD (r = 0.74) paradigms.(ABSTRACT TRUNCATED AT 250 WORDS)
A 74-year-old woman was found to have increasing proptosis in a blind, painful left eye with neovascular glaucoma. Uveal malignant melanoma with massive orbital involvement was diagnosed, and the patient underwent orbital exenteration, with preoperative and postoperative orbital irradiation. The tumor was a mixed-cell, diffuse uveal malignant melanoma with involvement of the optic nerve adjacent to the line of surgical transection and of the optic nerve sheath. Subsequently, the cerebrospinal fluid cytology disclosed cells consistent with malignant melanoma, despite the absence of neurologic signs or symptoms. Cerebrospinal fluid cytology is essential in such cases, and ultrasonography is of value.
It is generally accepted that interruption of the sympathetic pathway to the eye may result in iris hypochromia in human infants. Weanling Dutch belted rabbits were used as a model system to investigate whether the melanin synthesizing enzyme, tyrosinase, is regulated in the iris of the juvenile animal by adrenergic innervation. Although we did not find a significant decrease in tyrosine activity isolated from the sympathetically denervated iris, we did observe a tenfold fall in iris tyrosine activity between the 30th and 120th days of life in both intact and denervated irides. About 90% of the iris tyrosine activity was localized in the pigmented epithelium and the remaining tyrosinase activity was found in the stromal tissue. This distribution of tyrosine activity was not affected by sympathetic denervation or time.