David H. Kim

Non-invasive assessment of language lateralization by transcranial near infrared optical topography and functional MRI.

Near infrared optical topography (OT) is the simultaneous acquisition of hemoglobin absorption from an array of optical fibers on the scalp to construct maps of cortical activity. We demonstrate that OT can be used to determine lateralization of prefrontal areas to a language task that has been validated by functional MRI (fMRI). Studies were performed on six subjects using a visually presented language task. Laterality was quantified by the relative number of activated pixels in each hemisphere for fMRI, and the total hemoglobin responses in each hemisphere for OT. All subjects showed varying degrees of left hemisphere language dominance and the mean laterality indices for subjects who underwent both OT and fMRI were in good agreement. These studies demonstrate that OT gives predictions of hemispheric dominance that are consistent with fMRI. Due to the ease of use and portable nature of OT, it is anticipated that optical topography will be valuable tool for neurological examinations of cognitive function. Hum. Brain Mapping 16:183–189, 2002.

Chemoradiation as primary or adjuvant treatment for locally advanced carcinoma of the vulva

PURPOSE To determine the impact of primary or adjuvant chemotherapy and radiation (CRT) on the survival rates of patients with locally advanced vulvar carcinoma. METHODS AND MATERIALS Between 1973 and 1998, 54 patients with vulvar cancer were treated with radiation therapy, among which 20 received CRT, while 34 patients received radiation therapy (RT) alone. Of the 20 patients, 14 were treated for primary or recurrent disease (pCRT), and 6 after radical vulvectomy for high-risk disease (aCRT). Of the 34 patients, 12 were treated primarily (pRT) and 22 received adjuvant treatment (aRT). Chemotherapy consisted of 2 courses of 5-fluorouracil (5-FU) and mitomycin C administered during RT. Six patients received cisplatin in place of mitomycin C. In CRT groups, radiation was administered to the vulva, pelvic, and inguinal lymph nodes to a median dose of 45 Gy with additional 6-17 Gy to gross disease. In RT groups, the median dose to the microscopic diseases was 45 Gy. Nine patients received external beam boost and 16 patients received supplementary brachytherapy in the forms of (226)Ra or (241)Am plaques to sites of macroscopic disease. RESULTS Overall survival was superior in the patients treated with pCRT versus pRT with statistical significance (p = 0.04). There was also a statistically significant improvement in disease-specific (p = 0.03) and relapse-free survival (p = 0.01) favoring pCRT. No statistically significant trends of improved survival rates favoring aCRT over aRT were observed. CONCLUSION Concurrent radiation therapy and chemotherapy decreases local relapse rate, improves disease-specific and overall survival over RT alone as primary treatment for locally advanced vulvar cancer.

Prognostic Significance of Cyclooxygenase-2 in Oropharyngeal Squamous Cell Carcinoma

Purpose: To determine the relative prognostic significance of cyclooxygenase (COX)-2 expression in patients with oropharyngeal squamous cell carcinoma (SCC). Experimental Design: This retrospective cohort study included 82 patients with SCC referred to the Department of Therapeutic Radiology at Yale-New Haven Hospital (Connecticut) between 1980 and 1999 who were treated with primary external beam radiotherapy or gross total surgical resection and postoperative radiotherapy. A microarray of archival tumor tissue was constructed and stained with monoclonal antibodies directed against COX-2 and scored for intensity by a pathologist blinded to the clinical outcomes of the patients. COX-2 immunoreactivity and clinicopathological data were analyzed with respect to survival endpoints using bivariate and multivariate techniques. Results: Frequency of COX-2 overexpression was 45%. In multivariate analysis, COX-2 positivity predicted poor 3-year survival (P = 0.02; odds ratio = 0.41; 95% confidence interval, 0.20–0.84). Increasing age was significantly associated with increased 3-year survival (P = 0.03; odds ratio = 1.04; 95% confidence interval, 1.004–1.09). Positive COX-2 status trended toward predicting decreased 3-year disease-free survival. Conclusions: COX-2 was the most important predictor of poor survival in this patient cohort. In patients with oropharyngeal SCC treated with external-beam radiation therapy, overexpression of COX-2 may affect clinical outcome, and COX-2 may therefore prove valuable both as a prognostic factor and as a therapeutic target.

Lateral Connectivity in the Olfactory Bulb is Sparse and Segregated.

Lateral connections in the olfactory bulb were previously thought to be organized for center–surround inhibition. However, recent anatomical and physiological studies showed sparse and distributed interactions of inhibitory granule cells (GCs) which tended to be organized in columnar clusters. Little is known about how these distributed clusters are interconnected. In this study, we use transsynaptic tracing viruses bearing green or red fluorescent proteins to further elucidate mitral- and tufted-to-GC connectivity. Separate sites in the glomerular layer were injected with each virus. Columns with labeling from both viruses after transsynaptic spread show sparse red or green GCs which tended to be segregated. However, there was a higher incidence of co-labeled cells than chance would predict. Similar segregation of labeling is observed from dual injections into olfactory cortex. Collectively, these results suggest that neighboring mitral and tufted cells receive inhibitory inputs from segregated subsets of GCs, enabling inhibition of a center by specific and discontinuous lateral elements.

Center-surround vs. distance-independent lateral connectivity in the olfactory bulb

Lateral neuronal interactions are known to play important roles in sensory information processing. A center-on surround-off local circuit arrangement has been shown to play a role in mediating contrast enhancement in the visual, auditory, and somatosensory systems. The lateral connectivity and the influence of those connections have been less clear for the olfactory system. A critical question is whether the synaptic connections between the primary projection neurons, mitral and tufted (M/T) cells, and their main inhibitory interneurons, the granule cells (GCs), can support a center-surround motif. Here, we study this question by injecting a “center” in the glomerular layer of the olfactory bulb (OB) with a marker of synaptic connectivity, the pseudorabies virus (PRV), then examines the distribution of labeling in the “surround” of GCs. We use a novel method to score the degree to which the data fits a center-surround model vs. distance-independent connectivity. Data from 22 injections show that M/T cells generally form lateral connections with GCs in patterns that lie between the two extremes.