Reversible left hemispheric ischemia secondary to carotid compression in Eagle syndrome: surgical and CT angiographic correlation.

Symptoms of ipsilateral carotid artery compression secondary to an elongated styloid process or calcified stylohyoid ligament may be seen in Eagle syndrome. The patient will typically experience cervicofacial pain due to stimulation of the arterial nervous plexus. In addition, symptoms directly attributable to compression of the carotid artery may be seen, including visual symptoms and syncope. We report here the case of a patient who developed symptoms consistent with left hemispheric ischemia within 15 seconds of turning his head to the left. These symptoms were completely reversible on returning the head to the neutral position. No long-term sequelae were detected clinically or radiographically.

Recovery of lymphocyte status after radiotherapy.

A survey of the lymphocyte status is reported for 25 patients given routine radiotherapy for carcinoma of the cervix or carcinoma of the breast and other tumours. After an initial lymphopenia there was a return to the initial value of the lymphocyte count by the end of a 12 month period of observation. The PHA index was also measured in these patients and this also showed a progressive rise during the 12 month period following a minimal change after radiotherapy. There was no significant difference between the lymphocyte status of patients given radiotherapy above or below the diaphragm nor between patients with or without knwon metastases at the end of the 12 month period. An additional sample of eight patients with carcinoma of the breast showed a rise in lymphocyte count after surgery before the usual fall after radiotherapy.

Structural analysis of a novel interaction by calmodulin: high-affinity binding of a peptide in the absence of calcium.

The interaction of apocalmodulin (apoCaM) with a peptide (Neurop) based on the primary sequence of the calmodulin-binding domain of neuromodulin has been studied by nuclear magnetic resonance (NMR) methods. The NMR spectra of both apocalmodulin and its 1:1 complex with the Neurop peptide have been assigned by triple resonance and nuclear Overhauser effect-(NOE-) based strategies. ApoCaM displays many of the same basic structural features as calcium-saturated calmodulin. Analysis of observed chemical shifts and patterns of NOEs on the main chain indicates extensive and regular secondary structure throughout the N-terminal domain. In contrast, the helices of the C-terminal domain are somewhat irregular and are dynamically averaged. The EF-hands are intact in the N-terminal domain with the loops forming a short antiparallel beta sheet. Under low-salt conditions, two helix-loop-helix EF-hand motifs are present in the C-terminal domain of apoCaM but do not show interstrand NOEs. The spectral perturbations of apoCaM upon complexation with the Neurop peptide are relatively small with the larger chemical shift perturbations occurring in the C-terminal domain. The general secondary structure and tertiary organization appears to remain roughly the same as in free apoCaM. Stoichiometric titration of the apoCaM.Neurop complex with calcium indicates that the C-terminal domain EF-hands have a higher affinity for calcium than N-terminal domain EF-hands. Thus, this complex offers a unique opportunity to examine the structural and energetic consequences of calcium-dependent and calcium-independent binding of peptide to calmodulin.

The main chain dynamics of a peptide bound to calmodulin.

The main chain dynamics of a peptide corresponding to the smooth muscle myosin light chain kinase calmodulin-binding domain bound to calcium-saturated calmodulin have been studied by 15N relaxation techniques. Laboratory and rotating-frame spin lattice relaxation times and nuclear Overhauser effects have been determined for nine amide 15N sites in the peptide using two-dimensional NMR spectroscopy. The global motion of the 1:1 complex is shown to be isotropic and is characterized by a correlation time of 10 ns rad-1. The generalized order parameters (S2) of the nine backbone amide N-H vectors of the peptide all fall closely about a value of 0.83. The corresponding effective correlation times all tend to zero, indicating that, on the subnanosecond time scale, backbone motion of the bound peptide is highly restricted and dominated by extremely fast motions.