Positron emission tomography study of voluntary saccadic eye movements and spatial working memory

1. The purpose of this study is to define the cortical regions that subserve voluntary saccadic eye movements and spatial working memory in humans. 2. Regional cerebral blood flow (rCBF) during performance of oculomotor tasks was measured with [15O]-H2O positron emission tomography (PET). Eleven well-trained, healthy young adults performed the following tasks: visual fixation, visually guided saccades, antisaccades (a task in which subjects made saccades away from rather than toward peripheral targets), and either an oculomotor delayed response (ODR, a task requiring memory-guided saccades after a delay period) or a conditional antisaccade task (a task in which the color of the peripheral target determined whether a saccade toward or away from the target was required). An additional six subjects performed a sequential hand movement task to compare localization of hand-related motor cortex and the frontal eye fields (FEFs) and of the hand- and eye-movement-related regions of the supplementary motor area (SMA). 3. Friston's statistical parametric mapping (SPM) method was used to identify significant changes in rCBF associated with task performance. Because SPM does not take advantage of the anatomic information available in magnetic resonance (MR) scans, each subject's PET scan was registered to that individual's MR scan, after which all PET and MR studies were transformed to conform to a standard reference MR image set. Subtraction images were visually inspected while overlayed on the reference MR scan to which PET images had been aligned, in order to confirm anatomic localization of significant rCBF changes. 4. Compared with visual fixation, performing visually guided saccades led to a significant bilateral activation in FEF, cerebellum, striate cortex, and posterior temporal cortex. Right posterior thalamus activation was also observed. 5. The visually guided saccade task served as the comparison task for the ODR, antisaccade, and conditional antisaccade tasks for identification of task-related changes in rCBF beyond those associated with saccade execution. Performance on the ODR task was associated with a bilateral increase of rCBF in FEFs, SMA, dorsolateral prefrontal cortex (DLPFC), and posterior parietal cortex. The cortical regions of increased regional blood flow during the ODR task also showed increased rCBF during the antisaccade task; however, FEF and SMA activations were significant only in the right hemisphere. These findings closely parallel those of single-cell recording studies with behaving monkeys in indicating that FEF, DLPFC, SMA, and posterior parietal cortex perform computational activity for voluntary purposive saccades. 6. Comparison of PET scans obtained during performance of eye movement and hand movement tasks indicated that peak activations in FEF were located approximately 2 cm lateral and 1 cm anterior to those of hand-related motor cortex. The oculomotor area of SMA, the supplementary eye field (SEF), was located approximately 7-8 mm anterior and superior to the hand-related area of SMA. 7. During performance of antisaccade and ODR tasks, rCBF was significantly lower in ventromedial prefrontal cortex (PFC), along the rectus gyrus, and in ventral anterior cingulate cortex than during the visually guided saccade and fixation tasks. During the antisaccade task, the ventral region of lower rCBF involved medial structures including left ventral striatum and bilateral medial temporal-limbic cortex. During the ODR task, the ventral aspect of the region of lower rCBF extended laterally, rather than medially, to include the temporal poles. The lower blood flow observed in ventromedial PFC during both the antisaccade and ODR tasks, relative to the visually guided saccade and fixation tasks, suggests that modulation of output from ventromedial PFC to limbic cortex and the striatum may play a role in the voluntary control of saccadic eye movements, possibly in the suppression of responses that would interrupt

Expression and posttranslational modification of class III beta-tubulin during neuronal differentiation of P19 embryonal carcinoma cells

We have used a combination of immunofluorescence microscopy, northern blotting, ELISA, and isoelectric focusing to characterize the expression of neuronal Class III beta-tubulin in P19 embryonal carcinoma cells induced to differentiate along a neuronal pathway by retinoic acid. Following 48 h differentiation, beta-III tubulin mRNA is evident and beta-III tubulin appears in the mitotic spindle of neuroblasts. Neurite outgrowth is obvious by day 3, and beta-III tubulin protein and mRNA levels increase concurrently until approximately day 7, when beta-III mRNA levels begin to decrease while protein levels remain high. In addition, increasingly acidic beta-III tubulin isoforms appear during neuronal differentiation. The expression of these isoelectric variants occurs concomitant with a temporal increase in the levels of beta-III tubulin present in the colchicine-stable microtubules. These results implicate posttranslational modifications of beta-III tubulin in the increased microtubule stability noted in differentiating P19 neurons.

The effect of the neurolytic agent ethanol on cytoplasmic calcium in arterial smooth muscle and endothelium

BACKGROUND AND OBJECTIVES

Celiac plexus neurolysis, although effective in relieving pain associated with upper abdominal malignancy, occasionally results in paraplegia. Diffusion of the neurolytic agent to arteries supplying the spinal cord has been postulated as a cause, and previous studies with isolated lumbar segmental arteries have demonstrated contraction in response to ethanol and phenol. The mechanism of this contractile effect is unknown, but a role for insular free calcium (Ca2+i) is suggested by the known involvement of Ca2+i in both smooth muscle vasoconstriction and toxic cell injury. The authors sought to determine whether nontoxic concentrations of ethanol cause a direct elevation of Ca2+i in arterial smooth muscle and endothelium.

METHODS

Primary cultures of human aortic smooth muscle and endothelial cells were studied to determine the direct effect of ethanol independent of interactions with agonists or contractile proteins. Ca2+i levels were determined in single cells with digitized video fluorescence microscopy, using ratio imaging of the Ca2+i-sensitive fluorophore fura-2.

RESULTS

In aortic smooth muscle cells, initial Ca2+i was 98 +/- 41 nM (n = 59 cells). Histamine (10 microM) as a positive control caused an increase in Ca2+i, as expected. Ethanol alone, at doses of 2-5% (v/v) also caused a sustained elevation in Ca2+i of physiologically significant magnitude. Ethanol at doses of 5% or lower did not cause any visibly apparent injury within 30 minutes. In contrast, 10% or higher ethanol doses quickly caused membrane blebbing, a sign of toxic injury, followed by cell death within 20 minutes. Aortic endothelial cells were more resistant to ethanol than smooth muscle cells, in terms of both Ca2+i elevation and cell death.

CONCLUSIONS

Ethanol, even at nontoxic concentrations, has a direct effect on aortic smooth muscle Ca2+i, large enough to be associated with significant vasoconstriction. The findings suggest a possible role for pharmacologic agents that preserve Ca2+i homeostasis in protecting against neurolysis-induced paraplegia, although additional study is required before clinical application is appropriate.

Role of intraaortic balloon pump counterpulsation in high risk coronary rotational atherectomy

OBJECTIVES

This study sought to evaluate the role of intraaortic balloon pump counterpulsation in preventing hemodynamic instability and promoting a successful outcome during percutaneous transluminal coronary rotational atherectomy in high risk patients.

BACKGROUND

The application of rotational atherectomy has widened to include patients with complex lesions and left ventricular dysfunction. Although intraaortic balloon pumping has been successfully used to provide hemodynamic support during balloon angioplasty, its role in high risk rotational atherectomy has not yet been defined.

METHODS

In a retrospective review of 159 consecutive high risk patients who underwent rotational atherectomy, 28 had an intraaortic balloon pump placed electively before the procedure (Group 1) whereas 131 did not (Group 2).

RESULTS

Group 1 was older and more likely to have multivessel disease and left ventricular dysfunction. Augmented diastolic pressure was maintained > 90 mm Hg in all Group 1 patients, and significant procedure-related hypotension was encountered in nine Group 2 patients, requiring an emergency intraaortic balloon pump in five. Procedural success was achieved in all 28 patients in Group 1 and in 118 in Group 2 (p = 0.07). Slow flow occurred in 18% and 17% of Group 1 and 2 patients, respectively. Among patients with slow flow, non-Q wave myocardial infarction occurred only in Group 2 (0% vs. 27%). On multivariate analysis, elective intraaortic balloon pump placement was the only variable to correlate with a successful procedure uncomplicated by hypotension (p < 0.05). Hospital stay and vascular complications were similar in both groups.

CONCLUSIONS

Elective placement of an intraaortic balloon pump before coronary rotational atherectomy in selected high risk patients promotes both procedural hemodynamic stability and a successful outcome.

Absence/hypoplasia of tibia, polydactyly, retrocerebellar arachnoid cyst, and other anomalies: an autosomal recessive disorder

Absence or hypoplasia of the tibia has been reported to occur as an isolated hereditary malformation as well as a feature of several autosomal recessive and autosomal dominant syndromes. We report three sibs with absence or hypoplasia of the tibia in association with other malformations whose parents are first cousins once removed. These infants appear to have a "new" autosomal recessive syndrome.

Accumulation of microtubule-associated protein 1A (MAP1A) in differentiating P19 embryonal carcinoma cells

We have examined the accumulation of MAP1A in retinoic acid induced P19 embryonal carcinoma (EC) neurons. By immunofluorescent confocal microscopy, MAP1A was detected in the mitotic spindle of undifferentiated cells but was not evident in association with the interphase microtubules in most cells. By day 4 of differentiation, when neurite outgrowth was underway, MAP1A was co-localize with microtubules in all neurites but was absent from growth cones. By day 8, substantial neurite outgrowth had occurred and MAP1A was seen in all processes. At day 12, no further neurite outgrowth was evident and existing neurites were organized into fascicles. Western blotting and ELISA showed that MAP1A protein levels increased during differentiation. Peak accumulation occurred no later than day 8, coinciding with the period of neurite outgrowth, and then decreased after day 8. The results suggest that in differentiating P19 EC cells MAP1A modulates microtubule dynamics during neurite outgrowth.

Effects of taxol on the polymerization and posttranslational modification of class III beta-tubulin in P19 embryonal carcinoma cells

Undifferentiated P19 embryonal carcinoma cells and P19 cells induced to differentiate along a neuronal pathway by 10(-6) M retinoic acid were treated with taxol to examine the effects of this microtubule-stabilizing drug on the subcellular sorting of class III beta-tubulin and on neurite outgrowth. P19 cells were grown on cover slips and then treated with taxol at concentrations of 10(-6) to 10(-9) M for 24 h. The microtubule cytoskeleton was examined after double-immunofluorescence labelling with a monoclonal antibody to alpha-tubulin (YOL 1/34) and a monoclonal neuron-specific class III beta-tubulin antibody (TuJ1). Treatment of undifferentiated P19 cells with concentrations of taxol greater than 4 x 10(-8) M caused microtubule bundling and multiple aster formation and promoted polymerization of the low levels of class III beta-tubulin found in these cells. In neurons, at 2 x 10(-8) M taxol, bundling of microtubules at the base of the neurite was apparent. At taxol concentrations greater than 1 x 10(-7) M, enhanced assembly of class III beta-tubulin was apparent, although long neurites were not observed. Using isoelectric focusing followed by western blotting, we detected an additional isoform of class III beta-tubulin after treatment with 10(-6) M taxol. The results indicate taxol treatment alters the normal subcellular sorting of tubulin isotypes, promotes the polymerization and posttranslational modification of class III beta-tubulin, and interferes with neurite outgrowth.

Regional anesthesia and local anesthetic-induced systemic toxicity: seizure frequency and accompanying cardiovascular changes

We sought to determine the contemporary frequency of seizures, and the associated cardiovascular changes, resulting from local anesthetic-induced seizures in all patients undergoing brachial plexus, epidural, and caudal regional anesthetics. We investigated the following variables: development and treatment of seizure or cardiac arrest during the regional anesthetic, type of anesthetic (including local anesthetic used), gender, age, ASA physical status class and type of operation (elective or emergent). In addition, each patient who experienced a seizure underwent retrospective review of the acute event to determine the arterial blood pressure and heart rate changes accompanying the seizure, as well as details of the regional block technique. There was a significant difference between the rate of seizure development between epidural, brachia, and caudal anesthetics, with caudal > brachial > epidural. A significant difference was also noted in the rate of seizure development within types of brachial block, with supraclavicular and interscalene > axillary. No adverse cardiovascular, pulmonary or nervous system events were associated with any of the seizures, including the 16 patients who received bupivacaine blocks. The frequency of local anesthetic-induced seizures stratified by block type has a wide range, and cardiovascular collapse after bupivacaine-associated seizure has a low incidence.

Transient paraplegia following alcohol celiac plexus block

BACKGROUND AND OBJECTIVES

A pancreatic cancer patient developing transient paraplegia compatible with spinal cord ischemia, following alcohol celiac plexus neurolysis, is described.

METHODS

A 58-year-old man with metastatic pancreatic cancer underwent celiac (deep splanchnic) alcohol neurolysis for management of severe epigastric and midback pain. In spite of apparently adequate needle position, he developed transient paraplegia consistent with anterior spinal artery syndrome.

RESULTS

The clinical findings suggest ischemia of the anterior spinal cord with complete motor and sensory paralysis to a T8 spinal cord level resulting from an anterior spinal artery syndrome.

CONCLUSIONS

The cause of the limited bilateral transient paralysis following celiac plexus block in this patient may involve ischemia of the spinal cord associated with reversible arterial spasm following the injection of ethanol solution.

Identification of 92-kD gelatinase in human coronary atherosclerotic lesions. Association of active enzyme synthesis with unstable angina

BACKGROUND

Acute coronary ischemia is usually initiated by rupture of atherosclerotic plaque, leading to intracoronary thrombosis and clinical sequelae. The proximate cause of plaque rupture is unknown. Accordingly, we investigated the potential role of the 92-kD gelatinase member of the matrix metalloproteinase family in acute coronary ischemia.

METHODS AND RESULTS

Coronary atherectomy specimens from patients with atherosclerosis and an acute ischemic syndrome consistent with recent plaque rupture (unstable angina) (n = 12) were immunostained for the presence of 92-kD gelatinase; the results were compared with those obtained by identical study of atherectomy specimens from patients with atherosclerosis and angina but without acute ischemia (stable angina) (n = 12). Positive immunostaining for 92-kD gelatinase was present in 83% of specimens from both unstable and stable angina patients. However, intracellular localization of enzyme (indicating active synthesis) was documented in 10 of 10 positively stained specimens from patients with unstable angina compared with 3 of 10 positively stained specimens from patients with stable angina. Macrophages and smooth muscle cells were the major sources of 92-kD gelatinase in all specimens examined by immunostaining of adjacent sections.

CONCLUSIONS

92-kD gelatinase is commonly expressed in coronary arterial atherosclerotic lesions. Active synthesis of 92-kD gelatinase by macrophages and smooth muscle cells in atherosclerotic lesions may play a pathogenic role in the development of acute coronary ischemia.

Key factors in improving surgical resources

The health care environment across the country is undergoing unprecedented uncertainty and change, so it is imperative that hospital leaders develop processes that enhance their organization's ability to adapt to new realities and directions. The key factors in maximizing the utilization of resources to meet community demand involve corporate changes and active support from medical, nursing, professional and support staff. This article describes the methods adopted by one community hospital to improve the utilization of surgical resources, with particular emphasis on the process developed for allocating Operating Room time to support corporate priorities.

Increasing curvature of the normal fetal ductus arteriosus with advancing gestational age

In order to determine whether the configuration of the normal fetal ductus arteriosus changes with increasing gestational age, we prospectively collected oblique transverse sonographic images of the fetal thorax through the ductus arteriosus. Scans from 240 consecutive normal fetuses with gestational age 20 weeks or more were included in the study. The images were reviewed independently by two sonologists and the ductus arteriosus was graded as: (1) straight; (2) mildly curved (C-shaped, bending < 90 degrees from a straight line); or (3) markedly curved (C-shaped, bending > 90 degrees, or S-shaped). In cases where the two sonologists' gradings did not concur, the images were re-reviewed jointly by both sonologists and a grading was assigned by consensus. Forty-two cases were rejected, due to inadequate images. The ductus arteriosus was graded in 42 fetuses aged 20-25.9 weeks, 48 at 26-31.9 weeks, 74 at 32-37.9 weeks, and 34 at 38 weeks or more for a total of 198 cases. There was a significant trend to greater curvature with increasing gestational age (p < 0.0001). The frequency of a straight ductus arteriosus decreased steadily from 55% of fetuses aged 20-25.9 weeks to 3% of fetuses at 38 weeks or older, while the frequency of marked curvature increased from 2% in the youngest age group to 56% in the oldest. The proportion with mild curvature showed little variation throughout gestation. In summary, the configuration of the ductus arteriosus is variable but tends to become more curved as pregnancy proceeds. Marked curvature or tortuosity of the ductus arteriosus should not be misinterpreted as a great vessel anomaly.

Localization of small ovarian Sertoli-Leydig cell tumors by transvaginal sonography with color Doppler

Color Doppler ultrasound is a non-invasive diagnostic modality that has been gaining popularity in the evaluation of gynecological tumors. It demonstrates blood flow in a visually familiar way, and facilitates detection of neovascularity in pelvic tumors. In this article we describe, for the first time, a case in which a small androgen-producing ovarian tumor was localized by color Doppler ultrasound after other non-invasive imaging techniques failed.

An X-linked version of the affected-pedigree-member method of linkage analysis

The affected-pedigree-member (APM) method of linkage analysis detects linkage by testing for increased marker similarity between affected individuals in a pedigree. Thus, the APM method poses a 'one-locus' question about the inheritance of the marker; it requires and makes no assumptions about the inheritance of the disease. It only requires that one be able to accurately determine who is affected. Since the APM method is model free, it is an important tool in testing for linkage of genetically complex diseases for which it is difficult to determine or define an accurate genetic model. In addition, the APM method may be used as a model-free confirmatory test to complement traditional lod score analyses. The X-linked version of the APM method developed here now permits researchers to apply this method to test for linkage of complex diseases to X-linked markers.

Combined clozapine and electroconvulsive therapy for the treatment of drug-induced psychosis in Parkinson's disease

Drug-induced psychosis is a serious late complication of Parkinson's disease (PD) that requires aggressive treatment. Recent studies have found clozapine a highly effective and ECT a possibly useful intervention. Two cases are presented that illustrate a possible treatment role for ECT. The cases demonstrate that ECT has significant but short-lived antipsychotic effects when used alone. However, patients who do not respond to clozapine monotherapy can be given adjunctive treatment with ECT. The combination therapy resulted in abrupt alleviation of psychotic symptoms in one of the cases, and maintenance with low-dose clozapine allowed for long-term efficacy. On the basis of these findings, a therapeutic approach to patients with drug-induced psychosis in PD is suggested.

Modification of radiation-induced apoptosis in radiation- or hyperthermia-adapted human lymphocytes

We have investigated the influence of the cellular adaptive response to ionizing radiation on radiation-induced apoptosis in human cells. The adaptive response is believed to be a protective mechanism that confers resistance to the detrimental effects of ionizing radiation and that can be induced by different agents, including hyperthermia and radiation. We have used fluorescence analysis of DNA unwinding (FADU) to assay the induction of apoptosis in human peripheral blood lymphocytes by ionizing radiation. Using the FADU assay, we have observed the initial radiation-induced DNA damage, its subsequent disappearance due to enzymatic repair, and its time- and dose-dependent reappearance. We believe this reappearance of DNA damage to be indicative of the DNA fragmentation event associated with apoptosis. This interpretation has been supported at the individual cell level using an in situ terminal deoxynucleotidyl transferase (TDT) assay (Apoptag, Oncor Inc.), which detects the 3'-hydroxyl ends of fragmented DNA, and by fluorescence analysis of nuclear morphology in Hoechst 33258 stained cells. Pretreatment of cells with low-dose gamma-radiation (0.1 Gy) or mild hyperthermia (40 degrees C for 30 min) altered the extent of radiation-induced (3 Gy) apoptosis. Both pretreatments sensitized lymphocytes to become apoptotic after the 3-Gy radiation exposure. This sensitization may represent an adaptive response mechanism that reduces the risk that genetically damaged cells will proliferate. The ability to modify the probability of radiation-induced apoptosis may lower the cancer risk from a radiation exposure.

Validation of indirect measures of body fat in lactating cows

The objective of the study was to establish and compare equations that would estimate the body fat content of lactating dairy cows from different indirect techniques. The techniques used were body condition scoring, dilution of D2O in body water, and determination of mean fat cell size diameter of the subcutaneous, abdominal, and perirenal depots. Each technique was validated against direct determination of body fat content of the same lactating cows. To apply equations to high producing, lactating dairy cows, cows were from a herd producing more than 9500 kg of FCM/305 d, were lactating, and were in less than average body condition. Eight days prior to slaughter, a single injection of D2O was injected into the jugular vein, and body dilution was followed for 4 d. Cows were scored for body condition on the day of injection and weighed daily for the 4 d prior to slaughter. Samples of subcutaneous, perirenal, and omental adipose depots were taken, and adipocyte size and number were determined. Body fat was not predicted well by D2O space alone, but inclusion of BW did improve the prediction of body fat from this variable. The best equations were derived from use of BW with body condition score or subcutaneous fat cell diameter: observed body fat = -122.1 + .21 x BW + 36.0 x body condition score, and -195.6 + .290 x BW + .927 x subcutaneous fat cell diameter; standard errors of the estimate were 4.6 and 5.5 kg, respectively. Equations using diameters of abdominal and perirenal fat cells gave similar relationships. Equations using all four predictors (live BW, fat cell diameter, condition score, and D2O space) were only slightly improved over these equations. Thus, use of body condition score, adipocyte diameter, and BW in laboratory and field conditions may help in the study and management of the use of body fat in lactating dairy cows.

Role of topoisomerase II in the structural and functional evolution of mitogen-stimulated lymphocyte nuclei

To examine the role of DNA topoisomerase II (Topo II) in the mitogenic activation of mouse lymphocytes, we applied the Topo II inhibitor VM26 throughout the stimulation period and monitored morphological and functional parameters of lymphocyte activation. Cell viability and the usual increase in cell size were little affected at doses between 0.05 and 0.5 microM. DNA synthesis, however, was already significantly inhibited at 0.05 microM, with RNA synthesis inhibited to a lesser extent. Light microscope autoradiography showed that a smaller proportion of cells entered S phase, with each S phase cell incorporating less [3H]thymidine. In immunofluorescence studies, the nucleolar antigen fibrillarin was reduced, although only minor effects on the snRNP Sm antigen and the internal component labeled by antibody PI1 were observed. At the electron microscope level, nucleoli were remodeled and chromatin became aggregated. At a high dose of VM26 (5 microM), cells showed the expected high levels of apoptosis and strong inhibition in all activation parameters assayed. The results support the hypothesis that the Topo II beta isoform is involved in the very early phases of lymphocyte activation, with function of the Topo II alpha isoform, which is more sensitive to VM26, being required for progression through S phase.

Distal ureteral calculi: detection with vaginal US

PURPOSE

To describe the use of vaginal ultrasonography to identify distal ureteral calculi and hydroureter.

MATERIALS AND METHODS

Abdominal and vaginal sonography were performed in 13 women with distal ureteral calculi. Indications for sonography included flank pain, hematuria, and suspected appendicitis. Six patients were pregnant.

RESULTS

In each patient, vaginal sonograms demonstrated a distal ureteral calculus; in only two cases was the calculus detected with transabdominal sonography. Distal hydroureter was identified with vaginal scanning in each patient but with abdominal scanning in only two. Hydronephrosis was absent in three patients, mild in six, and moderate in four. Symmetric ureteral jets were noted at transabdominal sonography in two of nine patients. Follow-up transvaginal scans obtained shortly after passage of stones in two patients revealed swelling of the trigone but normal ureteral jets.

CONCLUSION

In symptomatic female patients, use of vaginal sonography should be considered to evaluate the distal ureter for calculi, particularly if the results of transabdominal examination are normal or inconclusive.