Proliferation and cell death in oligodendrogliomas

The rates of cell proliferation and of cell loss influence the growth rate of a tumour and reflect genetic changes. We studied proliferation and apoptosis in oligodendrogliomas and their relationship to progression of the tumours. Thirty-two cases of oligodendroglioma were retrieved spanning a 10-year period. The diagnosis and grade were reviewed and follow-up data obtained. Mitotic index (MI) and apoptotic index (AI) were determined from haematoxylin and eosin (H & E) stained sections. A labelling index (LI) of proliferating cells was obtained using the MIB1 antibody to the Ki-67 antigen. A further index of apoptosis was obtained using in situ end-labelling of DNA strand breaks (TUNEL index, TI). Fourteen cases were graded as II, 18 as III (1993 WHO). LI was significantly higher in grade III than in grade II tumours (P < 0.01) but the difference in apoptotic indices between grades was not significant. There was a significant (P = 0.036) positive correlation between the logarithms of TI and LI. Construction of survival curves demonstrated a significant difference in survival according to histological grade (P < 0.05). Stratification of cases by LI alone did not predict significantly different survival outcomes, and apoptotic indices did not demonstrate a relationship to survival. A positive relationship was demonstrated between proliferation and apoptosis in oligodendrogliomas. The levels of apoptosis observed indicate that this phenomenon may have an important influence on the overall rate of tumour growth.

Chondrosarcoma of the petrous apex. Dilemmas in diagnosis and treatment

A case of chrondrosarcoma of the petrous temporal bone is presented. Chondrosarcomas rarely occur intracranially and typically present apex mass. The dilemmas faced in the diagnosis and treatment of petrous apex chondrosarcomas are discussed. This case also gives interesting insight into the natural history of this tumour.

Paravertebral muscles in disease of the cervical spine

OBJECTIVES

Cervical spine disorders are common in the older population. The paravertebral muscles are essential to the support and stabilisation of the cervical spine but have been little studied. The aim was to determine whether pathological changes develop in these muscles in patients with severe cervical spine disease, which, if present, might contribute to the pathogenesis and symptomatology of their disorder.

METHODS

Open biopsies of superficial and deep paravertebral muscles were obtained during the course of surgical procedures to alleviate cervical myelopathy. Most of these patients had cervical spondylosis or rheumatoid arthritis involving the cervical spine. The biopsies were compared with muscle obtained at necropsy from patients without a history of cervical spine or neuromuscular disorder.

RESULTS

Muscle from both the study and control groups showed a similar range and severity of abnormalities. In several patients, grouped fibre atrophy suggested chronic partial denervation. Most biopsies showed type 1 fibre predominance and selective type 2 fibre atrophy. Ragged red fibres were a frequent finding and electron microscopy disclosed accumulations of mitochondria, a small proportion of which contained rounded, or longitudinally oriented, single osmiophilic inclusions. Fibres containing core-like areas were also frequent. These pathological features were seen with increasing severity and frequency with increasing age.

CONCLUSIONS

The paravertebral cervical muscles develop pathological abnormalities with increasing age with both neurogenic and myopathic features, the pathogenesis of which is probably multifactorial. Such a muscle disorder would be expected to be accompanied by functional impairment which may contribute to the development and symptomatology of cervical spine disease with increasing age.

Experimental herpes simplex virus type 1 (HSV-1) infection of the spinal cord and dorsal root ganglia

Host factors determining the outcome of herpes simplex virus type 1 (HSV-1) infection within neurons are poorly understood. This paper aims to identify regional differences in the behaviour of HSV-1 within the nervous system as an approach to investigating the role of the host environment in determining the outcome of infection. We describe a mouse model of HSV infection focused on motor neurons of the spinal cord, resulting from intramuscular injection (i.m.) and compare this with the behaviour of virus within sensory neurons following scarification of virus on to skin. Viral antigen was detectable immunohistochemically by 2 days in both models and disappeared by 9-11 days. The time course of acute infection was reflected in the i.m. group by quantitative plaque assay for virus. Inflammation and cell destruction occurred in both models, but clinical features and histological destruction were greater in the group infected via the intramuscular route. In the sensory ganglia, a latent state from which virus could be reactivated by explanation, was established with LATS expression detectable in many neurons at 35 days post-infection (p.i.), but not in non-neuronal cells. Expression of latency associated transcript (LATS) was detected in motor neutrons in spinal cords at 35 days p.i. providing evidence for establishment of a LATS-positive latent state at this site, and continued to be detectable up to 6 months post-infection. In addition, LATS was detected in white matter at late times, suggesting a non-neuronal site of latency. In contrast to the behaviour in sensory ganglia, induced reactivation from spinal cords, by explanation and nerve section, was a very rare event. We have shown that a LATS-positive latent state can be established within motor neurons of the CNS, but that there are regional differences in the biology and outcome of infection between the CNS and peripheral nervous system. We propose that this may be a useful model to study reproducibly, the behaviour of HSV-1 in a CNS environment and, by comparison with sensory ganglion infection, to explore host factors which may underlie these regional differences. The relevance of this model for using HSV-1 as a therapeutic vector for motor neurons is also discussed.

Virus-cell interactions in the nervous system and the role of the immune response

The outcome of a viral infection within the nervous system depends on a complex interplay between the virus, its target cell and the immune system. Recent research has elucidated a variety of mechanisms involved in these interactions and their role in the production of disease.