Selective inhibition of excitatory amino acids by divalent cations. A novel means for distinguishing N-methyl-D-aspartic acid-, kainate- and quisqualate-mediated actions in the mouse spinal cord

Biting and scratching behaviors produced by intrathecal injection of excitatory amino acid (EAA) agonists were examined to determine whether the biting and scratching behavioral effects produced by these compounds are altered selectively in vivo by coadministration with divalent cations. N-methyl-D-aspartate (NMDA)-induced behavior was inhibited by both magnesium and calcium but not by zinc. Kainic acid (KA)-induced behavioral activity was also inhibited by coadministration with calcium but not by magnesium or zinc. In contrast to both NMDA and KA, calcium, magnesium and zinc failed to alter the intensity of quisqualic acid (Quis)-induced biting and scratching behaviors. Based on this selective inhibition of the three EAA subtypes by divalent cations, we examined the behavioral responses produced by Glu and Asp in combination with calcium or magnesium to identify the receptor population involved in these motor effects. Calcium antagonized the biting and scratching behavior produced by i.t. injected Glu in contrast with Asp which was inhibited significantly by magnesium. Our results support the concept that Glu and Asp produce biting and scratching behaviors by an interaction with distinct receptor populations in the spinal cord. To date, there are no selective antagonists at the KA or Quis receptors. Thus, a systematic examination of the selective inhibition of EAA activity by divalent cations in addition to currently available pharmacologic antagonists may prove to be a useful approach to the identification of NMDA, KA and Quis receptor interactions.     

Tetanus: an uncommon cause of dysphagia

A 53-year-old woman was examined at our medical center because of progressive dysphagia of 14 days' duration and a severe inability to open her mouth and swallow saliva. A barium esophagogram showed no obstruction, but pooling of barium in the hypopharynx suggested a neuromuscular disorder. The clinical diagnosis of tetanus was confirmed by electromyography. With appropriate therapy, the patient recovered during a period of 6 weeks. This case illustrates both an uncommon cause of dysphagia and an uncommon initial manifestation of tetanus.     

Hand preferences and whole (Galago senegalensis)

The hand preferences in prey capture and whole-body turning biases after prey capture were assessed in 10 lesser bushbabies (Galago senegalensis) in 8 conditions designed to manipulate posture, visibility of prey and angle of reaching. Each subject received 60 trials in each test condition for a total of 480 trials. Seven subjects had a left-hand preference in food reaching, three right and none were ambipreferent. Eight subjects had a left whole-body turning bias, one right and one had no bias. No correlation was found between reach preference and turning bias. Bipedal posture facilitated the use of the dominant hand, whereas other manipulated conditions did not have a significant effect on hand use. A neuraxial arousal system is postulated as mediator of the bipedal effect on hand use.     

18F-FDG PET/CT for detecting nodal metastases in patients with oral cancer staged N0 by clinical examination and CT/MRI.

(18)F-FDG PET has a high accuracy in staging head and neck cancer, but its role in patients with clinically and radiographically negative necks (N0) is less clear. In particular, the value of combined PET/CT has not been determined in this group of patients. METHODS: In a prospective study, 31 patients with oral cancer and no evidence of lymph node metastases by clinical examination or CT/MRI underwent (18)F-FDG PET/CT before elective neck dissection. PET/CT findings were recorded by neck side (left or right) and lymph node level. PET/CT findings were compared with histopathology of dissected nodes, which was the standard of reference. RESULTS: Elective neck dissections (26 unilateral, 5 bilateral; a total of 36 neck sides), involving 142 nodal levels, were performed. Only 13 of 765 dissected lymph nodes harbored metastases. Histopathology revealed nodal metastases in 9 of 36 neck sides and 9 of 142 nodal levels. PET was TP in 6 nodal levels (6 neck sides), false-negative in 3 levels (3 neck sides), true-negative in 127 levels (23 neck sides), and false-positive in 6 levels (4 neck sides). The 3 false-negative findings occurred in metastases smaller than 3 mm or because of inability to distinguish between primary tumor and adjacent metastasis. TP and false-positive nodes exhibited similar standardized uptakes (4.8 +/- 1.1 vs. 4.2 +/- 1.0; P = not significant). Sensitivity and specificity were 67% and 85% on the basis of neck sides and 67% and 95% on the basis of number of nodal levels, respectively. If a decision regarding the need for neck dissection had been based solely on PET/CT, 3 false-negative necks would have been undertreated, and 4 false-positive necks would have been overtreated. CONCLUSION: (18)F-FDG PET/CT can identify lymph node metastases in a segment of patients with oral cancer and N0 neck. A negative test can exclude metastatic deposits with high specificity. Despite reasonably high overall accuracy, however, the clinical application of PET/CT in the N0 neck may be limited by the combination of limited sensitivity for small metastatic deposits and a relatively high number of false-positive findings. The surgical management of the N0 neck should therefore not be based on PET/CT findings alone.     

On the relation of PAG neurons to laryngeal and respiratory muscles during vocalization in the monkey

Despite evidence from previous unit recording, microstimulation, lesioning and anatomical studies, the functions of the midbrain periaqueductal gray (PAG) remain unclear. We attempted to clarify the function of the PAG by recording activity of PAG units along with laryngeal and respiratory electromyograms (EMG) during vocalization in awake monkeys. PAG units were classified with respect to vocalization on the basis of their discharge patterns as 'early burst', 'late burst', 'tonic-increase' and 'tonic-off', with the vast majority being of the early- and late-burst type. Early-burst cells were correlated most frequently with inspiratory muscles of the respiratory system and laryngeal abductor muscles. Late-burst cells were most clearly correlated with laryngeal adductor and expiratory respiratory muscles. Data from spike-triggered averaging and parametric correlations indicate that most cells are related to single muscles, but a significant number were related to functionally related groups of two or more muscles. The results suggest that the PAG determines qualitative aspects of vocalization by the multisynaptic action its cells have on laryngeal and respiratory motoneurons.     

Travel distance, age, and sex as factors in follow-up visit compliance in the post-gastric bypass population

BACKGROUND: There is no consensus regarding the optimal rate of follow-up in the post-bariatric surgery patient population. METHODS: The records of all patients who underwent laparoscopic Roux-en-Y gastric bypass from 2001 to 2003 were reviewed. Using patient zip codes, travel distances were calculated between the patients' places of residence and our clinic. Patients were then assigned to 1 of 3 cohorts according to the following distances: (1) < 50 miles, (2) 50 to 100 miles, and (3) > 100 miles. Patient compliance with follow-up appointments at 3 weeks, 3 months, 6 months, 9 months, and 12 months was analyzed. Linear trends were identified using the Mantel-Haenszel test. Age and sex were analyzed as possible predictors of compliance using the chi(2) test. P values < .05 were considered statistically significant. RESULTS: The study group comprised 150 patients (127 females and 23 males). The 3 cohorts contained 115, 21, and 14 patients, respectively. All patients in each cohort were compliant with the 3-week follow-up appointment. Although there were differences in compliance between cohorts at each of the remaining appointments, only the 9-month (70.3% vs 61.9% vs 35.7%) visit showed statistical significance (P = .035). The 6-month visit trended toward significance (85.2% vs 76.2% vs 64.3%; P = .088). Males were more likely to be compliant with the 12-month follow-up (P = .040). When controlling for sex, travel distance was also a predictor of compliance at this follow-up visit (P = .024). Age was not predictive of compliance (P = .827). CONCLUSION: Based on our findings, we conclude that travel distance from the clinic does not significantly affect compliance at the initial follow-up, 3-month, and 12-month appointments. However, distance does tend to affect compliance at the 6-month appointment and significantly affects compliance at the 9-month appointment. Males are more likely to be compliant at the 12 month follow-up visit. We must continue to strive for 100% follow-up in our post-bariatric surgery patients.