Gerard T. A. M. Bots

Somatic pairing of chromosome 1 centromeres in interphase nuclei of human cerebellum

SummaryInterphase nuclei isolated from paraffin-embedded tissue of four normal brains were hybridized with biotinated repetitive DNA probes specific for the (peri) centromeric regions of chromosomes 1 and 7. Hybridization results were visualized with a peroxidase-DAB system after which the number of specific signals per nucleus was counted using bright field microscopy. Using the probe specific for chromosome 7 (p7t1), both the cerebral and the cerebellar samples showed 2 spots in 82% and 83%, respectively, of the nuclei. In situ hybridization with the chromosome 1 probe (pUC1. 77) showed two spots in 69% of the cerebral nuclei. In cerebellar samples, hybridization with pUC1.77 resulted in only one large spot per nucleus in 82% of the cells. The average spot size in nuclei with one signal was about 1.6 times as large as that in nuclei with two signals. These observations suggest that the single large spot in the cerebellar cells is not the result of monosomy of chromosome 1 but that it reflects somatic pairing of the two chromosome 1 centromeres. Based on the size and the fraction of nuclei with one large spot, the small granular neuron is the most likely candidate. The difference between cerebral and cerebellar samples indicates that this somatic pairing of chromosome 1 is a cell-type-dependent phenomenon.

Choroid plexus papilloma in the posterior fossa

Choroid plexus papillomas in the posterior fossa can present with different clinical signs and symptoms. The tumors in the patients we discuss in this article originated from different sites of the choroid plexus. One patient, who had a fourth ventricle papilloma, experienced unsteady gait and episodes of dizziness over many years. The tumor was cystic an calcified, and adherent to the brain-stem. The second patient had only signs of increased intracranial pressure. A soft tumor was located in the cerebellomedullary cistern. The third patient, with a papilloma in the cerebellopontine angle, complained of hearing loss. This tumor was firmly adherent to the dura mater and looked exactly like a meningioma. The appearance on computed tomography scan, the macroscopic aspect, and the vascular supply of a papilloma in the posterior fossa can vary considerably.

Subacute progressive sensory ataxic neuronopathy after Rickettsia conorii infection

A case is presented in which sensory ataxic neuronopathy developed after serologically proven infection with Rickettsia conorii and continued to be progressive after appropriate antibiotic treatment. Electrophysiological studies showed decreasing sensory nerve conduction velocities ending with the absence of sensory nerve action potentials as well as peripheral and cortical somatosensory evoked potentials. Histological studies revealed a profound loss of myelinated fibres due to primarily axonal degeneration. The clinical course and the electrophysiological and histological findings suggest primary involvement of the dorsal root ganglion. Peripheral neuropathy due to infection with R. conorii is rare and usually of the mixed motor and sensory type. We believe this to be the first report of sensory ataxic neuronopathy associated with R. conorii infection.

Neuropathological findings in cerebral B-protein amyloidosis: Differences and similarities in those cases presenting as a cerebral hemorrhage and those presenting as a dementia of the Alzheimer type

Cerebral hemorrhages with amyloidosis and dementia of the Alzheimer type have many neuropathological findings in common, but there are also marked quantitative and qualitative differences. That makes it highly improbably that the B-protein amyloid depositions itself are the direct cause of extensive neuronal death and dementia in DAT.