Dynein-dynactin complex subunits are differentially localized in brain and spinal cord, with selective involvement in pathological features of neurodegenerative disease.

AIMS: The dynein-dynactin complex, mostly recognized for axonal retrograde transport in neurones, has an ever growing list of essential subcellular functions. Here, the distribution of complex subunits in human central nervous system (CNS) has been assessed using immunohistochemistry in order to test the hypothesis that this may be altered in neurodegenerative disease. METHODS: Three dynactin and two dynein subunits were immunolocalized in the CNS of human post mortem sections from motor neurone disease, Alzheimer's disease and patients with no neurological disease. RESULTS: Unexpectedly, coordinated distribution of complex subunits was not evident, even in normal tissues. Complex subunits were differentially localized in brain and spinal cord, and localization of certain subunits, but not others, occurred in pathological structures of motor neurone and Alzheimer's diseases. CONCLUSIONS: These results suggest that dynein-dynactin complex subunits may have specific subcellular roles, and primary events that disturb the function of individual components may result in disequilibrium of subunit pools, with the possibility that availability for normal cytoplasmic functions becomes impaired, with consequent organelle and axonal transport misfunction.

Dural haemorrhage in non-traumatic infant deaths: does it explain the bleeding in 'shaken baby syndrome'?

A histological review of dura mater taken from a post-mortem series of 50 paediatric cases aged up to 5 months revealed fresh bleeding in the dura in 36/50, the bleeding ranging from small perivascular haemorrhages to extensive haemorrhage which had ruptured onto the surface of the dura. Severe hypoxia had been documented clinically in 27 of the 36 cases (75%). In a similar review of three infants presenting with classical 'shaken baby syndrome', intradural haemorrhage was also found, in addition to subdural bleeding, and we believe that our findings may have relevance to the pathogenesis of some infantile subdural haemorrhage. Recent work has shown that, in a proportion of infants with fatal head injury, there is little traumatic brain damage and that the significant finding is craniocervical injury, which causes respiratory abnormalities, severe global hypoxia and brain swelling, with raised intracranial pressure. We propose that, in such infants, a combination of severe hypoxia, brain swelling and raised central venous pressure causes blood to leak from intracranial veins into the subdural space, and that the cause of the subdural bleeding in some cases of infant head injury is therefore not traumatic rupture of bridging veins, but a phenomenon of immaturity. Hypoxia with brain swelling would also account for retinal haemorrhages, and so provide a unified hypothesis for the clinical and neuropathological findings in cases of infant head injury, without impact or considerable force being necessary.

Thromboxane synthase immunohistochemistry in inflammatory bowel disease.

BACKGROUND: Thromboxanes are produced in excess in inflammatory bowel disease. Preliminary reports suggest that ridogrel, a thromboxane synthase inhibitor, is anti-inflammatory and may have therapeutic benefits in patients with ulcerative colitis. AIMS: To investigate the immunohistochemical expression of thromboxane synthase in the colorectal mucosa of patients with inflammatory bowel disease. METHODS: Immunostaining of colonic biopsies from patients with inflammatory bowel disease (n = 13) and controls (n = 5) was performed using a monoclonal antibody to human thromboxane synthase. The extent of staining in cells of the lamina propria was compared in patient and control groups, and was assessed in relation to disease activity scored macroscopically and histologically. RESULTS: The percentage of cells in the lamina propria staining for thromboxane synthase was higher in patients with active inflammatory bowel disease than in those with inactive disease or in controls (p = 0.02 and p = 0.002, respectively). There was a direct correlation between disease activity, measured endoscopically and histologically, and the percentage of lamina propria cells staining for thromboxane synthase (R = 0.71, p = 0.001 and R = 0.72, p = 0.001, respectively). CONCLUSIONS: Increased thromboxane synthase expression in lamina propria cells occurs in active inflammatory bowel disease. It is possible that this results in increased thromboxane synthesis, which may in turn contribute to mucosal inflammation and intramucosal thrombogenesis.

Neuropathology of inflicted head injury in children. I. Patterns of brain damage.

Fifty-three cases of non-accidental head injury in children were subjected to detailed neuropathological study, which included immunocytochemistry for microscopic damage. Clinical details were available for all the cases. There were 37 infants, age at head injury ranging from 20 days to 9 months, and 16 children (range 13 months to 8 years). The most common injuries were skull fractures (36% of cases), acute subdural bleeding (72%) and retinal haemorrhages (71%); the most usual cause of death was raised intracranial pressure secondary to brain swelling (82%). On microscopy, severe hypoxic brain damage was present in 77% of cases. While vascular axonal damage was found in 21 out of 53 cases, diffuse traumatic axonal injury was present in only three. Eleven additional cases, all of them infants, showed evidence of localized axonal injury to the craniocervical junction or the cervical cord. When the data were analysed by median age at head injury, statistically significant patterns of age-related damage emerged. Our study shows that infants of 2-3 months typically present with a history of apnoea or other breathing abnormalities, show axonal damage at the craniocervical junction, and tend also to have a skull fracture, a thin film of subdural haemorrhage, but lack extracranial injury. Children over 1 year are more likely to suffer severe extracranial, particularly abdominal, injuries. They tend to have larger subdural haemorrhages, and where traumatic axonal injury is present, show patterns of hemispheric white matter damage more akin to those reported in adults. Diffuse axonal injury is an uncommon sequel of inflicted head injury in children.

Neuropathology of inflicted head injury in children. II. Microscopic brain injury in infants.

There are very few reports in the literature dealing with the neuropathology of infant head injury, and the question of whether diffuse traumatic brain damage [diffuse axonal injury (DAI)] occurs in such children has not yet been reliably established by detailed neuropathological studies. We report the findings in the brains of a series of 37 infants aged 9 months or less, all of whom died from inflicted head injuries, and 14 control infants who died of other causes. Axonal damage was identified using immunohistochemistry for beta-amyloid precursor protein. Full clinical details were available for each case, the most constant of which in the study cohort was an episode of significant apnoea at presentation, found to have been recorded in 75% of cases. Global hypoxic damage was the most common histological finding. Widespread axonal damage, interpreted as vascular, was present in 13 cases, but widespread traumatic axonal injury was found in only two children, both of whom had severe head injuries with multiple skull fractures. Epidural cervical haemorrhage and focal axonal damage to the brainstem and the spinal nerve roots, found in 11 cases but not in controls, indicate that the craniocervical junction is vulnerable in infant head injury, the neuropathology being that of stretch injury from cervical hyperextension/flexion. Damage to this region could account for the observed apnoea, which could in turn lead to hypoxic damage and brain swelling. The observation that the predominant histological abnormality in cases of inflicted head injury in the very young is diffuse hypoxic brain damage, not DAI, can be explained in one of two ways: either the unmyelinated axon of the immature cerebral hemispheres is relatively resistant to traumatic damage, or in shaking-type injuries the brain is not exposed to the forces necessary to produce DAI.

Smooth muscle inclusion bodies in slow transit constipation.

Slow transit constipation (STC) is a disorder of intestinal motility of unknown aetiology. Myopathies, including those characterized by the finding of inclusion bodies, have been described in enteric disorders. Amphophilic inclusion bodies have been reported in the muscularis externa of the colon of STC patients. This study formally tested the hypothesis that these represent a primary muscle disorder, specific to STC. In a systematic, blinded, dual observer qualitative and quantitative analysis, colonic and ileal tissue from patients with STC (n=36) were compared with selected control populations: total colonic aganglionosis (n=10), Chagas' disease (n=6), isolated rectal evacuation disorders (n=6), and a control population of a range of ages (n=80). All sections were stained with haematoxylin and eosin and periodic acid Schiff. Further immunostains were used in an attempt to determine inclusion body composition. Round or ovoid (4-22 microm diameter) amphophilic inclusions increased in number in normal subjects with age. Inclusions were more frequent in idiopathic STC than in age-matched controls or rectal evacuation disorders [ileum (33% vs. 9%), ascending (50% vs. 19%, p<0.05), and sigmoid colon (43% vs. 20%)] and were very frequent in the sigmoid (71%) of patients with STC arising after pelvic surgery. The number of inclusions per unit area was significantly higher in patients with STC (p<0.001). Inclusions were found in all Chagas' patients, but not with aganglionosis. It was not possible to determine inclusion body composition, despite the use of a wide range of conventional and immunostains. This study demonstrates that inclusion body myopathy is identifiable in patients with STC and that it may arise secondary to denervation.

A systematic, genome-wide, phenotype-driven mutagenesis programme for gene function studies in the mouse.

As the human genome project approaches completion, the challenge for mammalian geneticists is to develop approaches for the systematic determination of mammalian gene function. Mouse mutagenesis will be a key element of studies of gene function. Phenotype-driven approaches using the chemical mutagen ethylnitrosourea (ENU) represent a potentially efficient route for the generation of large numbers of mutant mice that can be screened for novel phenotypes. The advantage of this approach is that, in assessing gene function, no a priori assumptions are made about the genes involved in any pathway. Phenotype-driven mutagenesis is thus an effective method for the identification of novel genes and pathways. We have undertaken a genome-wide, phenotype-driven screen for dominant mutations in the mouse. We generated and screened over 26,000 mice, and recovered some 500 new mouse mutants. Our work, along with the programme reported in the accompanying paper, has led to a substantial increase in the mouse mutant resource and represents a first step towards systematic studies of gene function in mammalian genetics.

p53 expression in phyllodes tumours is associated with histological features of malignancy but does not predict outcome.

AIMS: To study p53 protein expression in phyllodes tumours of the breast, with particular attention to its prevalence and to its relationship with histological features and clinical outcome. METHODS AND RESULTS: Stromal and epithelial p53 immunohistochemical expression was studied in 57 phyllodes tumours (27 benign, 17 borderline, 13 malignant) using an avidin-biotin peroxidase method. High levels of expression (> 30% of stromal nuclei) were found in eight phyllodes tumours (14%). p53 expression was associated with tumour grade (P = 0.001), prominent stromal overgrowth (P = 0.0003), prominent stromal nuclear pleomorphism (P = 0.006), high stromal mitotic count (P = 0.05), and an infiltrative tumour margin (P = 0. 05). Six patients were lost to follow-up after surgery. Mean follow-up time of the remaining 51 patients was 7.3 years (median 4. 3, range 0.5-25) or until death. Sixteen patients (31%) experienced tumour recurrence. Recurrence was more likely if there was an infiltrative tumour margin (P = 0.006) or prominent stromal overgrowth (P = 0.04) but not p53 expression (P = 0.55). A minority of recurrences expressed p53 more extensively than their primary counterparts. There were five tumour-related deaths (10% of patients). Death was associated with high grade (P = 0.0002), prominent stromal overgrowth (P = 0.0001), an infiltrative margin (P = 0.0002), prominent nuclear pleomorphism (P = 0.005), a high mitotic count (P = 0.01) and tumour size (P = 0.03). Again, p53 expression was not associated with tumour-related survival (P = 0. 13). CONCLUSIONS: p53 abnormalities occur in a minority of borderline and malignant phyllodes tumours. p53 expression is associated with known negative prognostic factors, but does not appear to be a useful determinant of tumour recurrence or long-term survival.

Transplacental carcinogenesis with radioactive phosphorus: the effects of promoting agents.

In a previous experiment, using 32P as a potential transplacental carcinogen in rats, we found that the isotope caused life-span shortening, reduced growth and caused ante-dating of the time of the tumour occurrence. Liver cell changes (nuclear atypia, variation in cell size) were noted and suggested liver cell damage, possible 'initiation'. A phorbol ester (TPA) and a high fat/high protein diet were used as promoting agents on further transplacentally irradiated rats. The results were identical to the previous experiment; no evidence of promotion was found.

Computer programs in cytology reporting and record keeping.

Large numbers of specimens are handled by cytology laboratories. There is great variation in their origin, a need for a name and disease index and for statistical data about the source and nature of the specimens. A computer program was devised to reduce this workload and to improve the accuracy of record keeping. Much of the tedium of this important aspect of laboratory function can thus be removed.

Transplacental carcinogenesis with radioactive phosphorus.

1 An attempt was made to produce a model of osteogenic sarcoma using 32P transplacentally. 2 Fetal tissues appeared to be resistant to irradiation as no tumour was induced at an increased frequency in treated animals. 3 Tumours that normally occur in our strain (Sprague-Dawley rats) showed a clear tendancy to occur earlier in post-natal life in treated animals compared with controls.

Computer programs in histopathology record keeping.

Increasing work loads, changes in the nature of data obtained from biopsies, and the use of laboratory statistics in determining financial provision for pathological services combine to enhance the value of computer generated results and indexing in histopathology. The system described here depends on an indexed file system using the Basic Plus-2 language with a PDP-11 computer and SNOP. Error traps are included. The system is designed for secretarial use, SNOP coding being carried out by medical staff.

The effects of aspirin on the development of the mouse third molar. A potential screening system for weak teratogens.

Aspirin is teratogenic at high doses in rodents. A dose related effect is shown at much lower levels in an animal testing system which permits subthreshold effects on development to be measured. This system, which depends on changes in tooth size in the mouse, has advantages in assessing weak or cumulative teratogens.