Coinfection of the central nervous system by cytomegalovirus and herpes simplex virus type 1 or 2 in AIDS patients: autopsy study on 82 cases by immunohistochemistry and polymerase chain reaction.

We evaluated the frequency and histopathological features of concomitant infections of the central nervous system (CNS) with cytomegalovirus (CMV) and herpes simplex viruses type 1 or 2 (HSV1/2) in a large series of patients who had died from AIDS. Eighty-two autopsy cases with a histological diagnosis of CMV necrotizing encephalitis were examined retrospectively. CMV and HSV1/2 were detected by immunohistochemistry (IHC) with poly- and monoclonal antibodies and by nested polymerase chain reaction (PCR) for HSV 1 and 2 on DNA extracted from paraffin blocks. PCR for a beta-globin genomic sequence was performed in all IHC-positive cases to verify the integrity of extracted DNA. Concomitant CMV/HSV infections were demonstrated by IHC in 13 cases (16%); using monoclonal antibodies, HSV1 was found in 9 cases and HSV2 in 4 cases. In half of the cases, HSV1- or HSV2-positive cells represented more than 25% of immunopositive CMV cells. In all 13 cases, double immunochemical staining showed cells containing both CMV and HSV antigens. PCR for HSV1 and 2 was positive in only 7 of 13 cases (5 HSV1 and 2 HSV2). In the remaining 6 negative cases PCR for beta-globin was also repeatedly negative. HSV1 or 2 infection can be demonstrated by IHC in a significant proportion of AIDS cases with necrotizing CMV encephalitis. Nested PCR for HSV1 and 2 on DNA extracted from formalin-fixed and paraffin-embedded autopsy tissues was positive in only slighty above 50% of IHC-positive cases.

Rotary subluxation of the scaphoid: a spectrum of instability.

Rotary subluxation of the scaphoid is not an "all or nothing" phenomenon, but a spectrum of instability including constant displacement of the scaphoid apparent on plain non-stress radiographs (the previously defined static type), subluxation seen only on loading X-rays or other special studies ("dynamic"), and instability demonstrable on physical examination but not by radiographic studies ("predynamic"). A clinical study of 1,000 random individuals was carried out to determine the incidence of unilateral hypermobility of the scaphoid. 21% of the subjects were found to have an abnormal difference in mobility between their scaphoids. The incidence of significant symptoms and physical findings associated with this hypermobility was determined.

The contribution of the dorsal and ventral roots of the tibial nerve in the propagation of the spinal somatosensory evoked potential in cats.

This study employed selective unilateral dorsal and ventral rhizotomy to examine the contribution of both the dorsal and ventral roots of the tibial nerve in the induction of the spinal somatosensory evoked potential (SSEP) in the cat. The spinal roots of origin of the tibial nerve in the cat were determined by retrograde transport of horseradish peroxidase (HRP). Spinal roots L6, L7, and S1 were found to give rise to the cat tibial nerve. Physiologic monitoring showed that the dorsal roots at these levels primarily contribute to the induction of the SSEP, but the ventral roots also make a small contribution. Because bilateral tibial nerve stimulation was found to mask a root injury on one side, we recommend sequential unilateral peripheral nerve stimulation when using SSEP during operations on the spine.