Platinum carboxylato-pendant-arm macrocycles: structure, redox properties and anti-cancer potential.

In an attempt to generate new platinum compounds that may be effective in the treatment of cancer, as well as having a lower toxicity than traditional platins and being orally viable, we are studing the synthesis and reactivity of platinum complexes of tetraazamacrocycles bearing carboxylato pendant arms. We have synthesized adducts of meso- and rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-1,7-diacetic acid (L(1)H(2)). The meso-Pt(II)L(1) complex is unstable with respect to disproportionation, forming platinum metal and [meso-Pt(IV)L(1)](2+). The rac-isomer shows less tendency to disproportionate. Cyclic voltammetry suggests that the rac-Pt(II)L(1) complex undergoes two one-electron oxidations. Using bis-triazacyclononanenickel(III), [Ni(III)(tacn)(2)](3+) as an outer-sphere oxidant, the self-exchange rate for the [Pt(II/III)L](0/+) couple has been estimated at 0.034 M(-1) s(-1).

Diffuse axonal pathology detected with magnetization transfer imaging following brain injury in the pig.

This study was designed to evaluate with magnetization transfer imaging (MTI) and conventional magnetic resonance (MR) imaging the manifestation of diffuse axonal injury (DAI) in an animal model of injury via nonimpact coronal plane rotational acceleration. A second objective was to investigate the diagnostic use of quantitative MTR imaging based on statistical parameters in a single subject, as opposed to grouped analysis. Seven mini-swine were subjected to brain trauma known to produce isolated DAI and to MR imaging at two time points. Following sacrifice, the brains were harvested for histopathologic examination. Magnetization transfer ratio (MTR) maps were generated for double-blinded comparison of regions with abnormal MTR values and regions with documented DAI. Positive and negative predictive values for MTR detection of DAI were 67 and 56%, respectively, and in acute studies alone, 89 and 61%. Gains in sensitivity over conventional imaging for detection of DAI were demonstrated.

Renal osteodystrophy of the cervical spine: neurosurgical implications.

Renal osteodystrophy describes the changes in bone physiology seen in renal failure. Traditionally, these changes resulted in mild neurological sequelae that were effectively managed medically. Despite the often severe destruction seen on x-ray, surgical therapy has not been reported extensively. With increasing numbers of long-term hemodialysis survivors, however, a newly recognized erosive spondyloarthropathy with extensive bony destruction is seen more frequently. These changes can mimic the radiographic appearance of osteomyelitis, not an uncommon sequela of hemodialysis patients; therefore, this diagnosis must be considered. Although renal osteodystrophy can be seen throughout the spine, reports of significant cervical spine involvement are uncommon. We present our experience with six cases of renal osteodystrophy of the cervical spine requiring surgical intervention for instability or cord compression. Osteomyelitis was present in two of the patients. The pathophysiology and radiographic characteristics of renal osteodystrophy and the incidence of osteomyelitis are discussed. Fusion techniques, including the use of anterior and posterior internal and external stabilization, are presented. These patients represent a therapeutic challenge for the neurosurgeon, given the underlying bone pathology.

Clinical experience with a fiberoptic intracranial pressure monitor.

Retrospective clinical experience with our first 46 patients monitored with a fiberoptic intracranial pressure device is described. In 43 of 46 patients, the transducer was introduced into brain parenchyma. A ventriculostomy system was used in 3 of 46 patients. The monitoring system was generally characterized by ease of placement and system maintenance and by technical simplicity. Several problems were encountered, including breakage of system components (12%), erroneous readings requiring transducer repositioning (8.6%), epidural hematoma (3.4%), and infection (1.7%). No infections or hematomas occurred in the 3 cases in which the ventriculostomy system was used. Overall, our experience with the Camino intracranial pressure fiberoptic monitoring system confirms previous reports of its favorable features.