The Rectal approach to neuropathology

A Standardized Method of Applying Toluidine Blue Metachromatic Staining for Assessment of Chondrogenesis

OBJECTIVES

Staining with toluidine blue is a well-established procedure for the histological assessment of cartilaginous- and chondrogenic-differentiated tissues. Being a cationic dye, toluidine blue staining visualizes proteoglycans in a tissue because of its high affinity for the sulfate groups in proteoglycans. It is generally accepted that metachromatic staining with toluidine blue represents cartilaginous matrix and that the degree of positive staining corresponds with the amount of proteoglycans.

DESIGN

Articular cartilage and pellets of chondrocytes or bone marrow stromal cells were analyzed with a standardized staining procedure for toluidine blue.

RESULTS

In the present study, we illustrate why such an assumption is invalid unless a detailed description of the procedure and/or reference to a detailed published method are provided. This is because the staining specificity and intensity depend, as we have shown, on the pH of the staining solution, the use of dehydration, and on staining time.

CONCLUSIONS

We can, therefore, suggest a well-controlled standardized protocol for toluidine blue staining, which provides an easy and simple selective staining technique for the assessment of cartilage tissue and proteoglycan development in chondrogenic differentiation. If this procedure is not used, then investigators must provide sufficient technical information concerning the staining protocol to allow an assessment of the validity of the staining results.

Neonatal adrenoleukodystrophy: a clinical, pathologic, and biochemical study

Neonatal adrenoleukodystrophy constitutes a distinct genetic disorder of autosomal recessive inheritance, and is distinguishable from the cerebro-hepato-renal syndrome of Zellweger and X-linked juvenile adrenoleukodystrophy, although all three conditions store very long chain fatty acids. Abnormal clinical features in neonatal adrenoleukodystrophy are generally present at birth, and include muscle hypotonia, severe psychomotor retardation, and failure to thrive. These infants are generally blind and deaf, with seizures developing during their first few weeks. A retinopathic "leopard spot" is common, and should help identify this disorder. The brains of four infants who died of neonatal adrenoleukodystrophy were biochemically analyzed for complex lipids, including cholesterol, cholesterol esters, total phospholipids, total galactolipids, and gangliosides. Additional analyses included the separation and identification of very long chain fatty acids and various forms of brain plasmalogen. Analyses of brains with neonatal adrenoleukodystrophy revealed the chemical identification of at least two stored lipid products. Very long chain fatty acids are present, especially in cholesterol esters, and vinyl ether ethanolamine plasmalogens are markedly elevated. The storage of vinyl ether plasmalogen in brains of infants dying of neonatal adrenoleukodystrophy clearly distinguishes them from those with cerebro-hepato-renal syndrome of Zellweger, which fail to synthesize plasmalogens.

Maternal manganese restriction increases susceptibility to high-fat diet-induced dyslipidemia and altered adipose function in WNIN male rat offspring

Growth in utero is largely a reflection of nutrient and oxygen supply to the foetus. We studied the effects of Mn restriction per se, maternal Mn restriction, and postnatal high-fat feeding in modulating body composition, lipid metabolism and adipocyte function in Wistar/NIN (WNIN) rat offspring. Female weanling, WNIN rats received ad libitum for 4 months, a control or Mn-restricted diet and were mated with control males. Some restricted mothers were rehabilitated with control diet from conception (MnRC) or parturition (MnRP), and their offspring were raised on control diet. Some restricted offspring were weaned onto control diet (MnRW), while others continued on restricted diet throughout (MnR). A set of offspring from each group was fed high-fat diet from 9 months onwards. Body composition, adipocytes function, and lipid metabolism were monitored in male rat offspring at regular intervals. Maternal manganese restriction increased the susceptibility of the offspring to high-fat-induced adiposity, dyslipidaemia, and a proinflammatory state but did not affect their glycemic or insulin status.

The pathologist's approach to the diagnosis of metabolic disease

Many inborn errors of metabolism have tissue changes that suggest or indicate a diagnosis on morphologic bases. This emphasizes the involvement of the pathologist in the study of tissues obtained by biopsy as part of the diagnostic workup of cases with clinical evidence suggesting a metabolic disorder. Some of these diseases involve proteins with enzymatic activity with a consequent backlog of precursor metabolites. If these metabolites are insoluble or compartmentalized in cells, they accumulate in tissues. The diagnosis in those cases rests on establishing the nature of the accumulated materials and their topographic distribution. In some storage diseases, the abnormal substance can be identified in the affected tissues by histochemistry or ultrastructure. Another group of inborn disorders of metabolism produce changes in subcellular organelles such as peroxisomes and mitochondria. A third group is expressed by rather unique tissue changes which strongly suggest the diagnosis of metabolic disease.

Diagnostic morphology of human eye-related storage disorders

While retina and other ocular tissues are involved clinically and morphologically in a variety of lysosomal disorders, it is only the conjunctiva that is accessible by biopsy to morphological, i.e., electron microscopic recognition of the patient's individual lysosomal disease. However, this procedure is not utilized by many. Instead, skin and circulating lymphocytes are the most frequently obtained tissues for diagnostic investigation, as skin contains an abundance of diversified cell types for morphological examination and simultaneously fibroblasts to be cultured for biochemical investigation. It is the tissue most suitable for identifying lysosomal disorders and parallels in diagnostic significance that of the conjunctiva. Skeletal muscle, liver and peripheral nerves are only rarely biopsied in elucidating a lysosomal disorder, to-day largely due to ignorance of the examiner who orders a biopsy without prior consultation of either the biochemist or the neuropathologist.

Intestinal neuronal degeneration in a patient with chronic idiopathic intestinal pseudoobstruction

Neuropathological examination of the gut in a patient with chronic idiopathic intestinal pseudoobstruction and temporal lobe epilepsy showed a degeneration of Auerbach's and of Meissner's plexus. The extent of generative changes increased in an aboral to oral direction. Neuronal degeneration was characterized by ballooning of the cytoplasm of the ganglial cells, by a hyperargyrophilia, a shortening and dilation of cell processes, and a progressive fragmentation and loss of axons. In rectal biopsies, a PAS-positive granular material was detected in the cytoplasm of ballooned ganglial cells. A severe peripheral neuropathy with fiber degeneration in the posterior columns and axonal lesions within ventral nerve roots and a more recent fiber degeneration in the lateral columns corresponding to the picture of subacute combined degeneration of the spinal cord and a symmetrical Ammon's horn sclerosis was present. This case of progressive intestinal neuronal degeneration of unknown origin is a newly described condition leading to chronic idiopathic intestinal pseudoobstruction.

Four cases of late onset metachromatic leucodystrophy in a family: clinical, biochemical and neuropathological studies

Four cases of familial metachromatic leucodystrophy are described: the age of onset ranged from 15 to 21 years. Mental deterioration was the earliest clinical sign to be noted and all progressed to severe dementia. The arylsulphatase activity in peripheral leucocytes of the patients was very low, 5 to 15 nmol/h/mg protein, moderately reduced in the heterozygote, 40 nmol/h/mg protein, compared with control values of 60-160 nmol/h/mg protein. Sural nerve biopsies in two cases showed perivascular macrophages filled with metachromatic material and electron microscopy showed typical inclusions in Schwann cell cytoplasm. Necropsy in one of the cases revealed severe demyelination mainly in the cerebral hemispheres with metachromatic material in macrophages and neurons.

Metachromatic leucodystrophy: review of 38 cases

Clinical and laboratory features of 38 children suffering from metachromatic leucodystrophy (MLD) are reported. Twenty-four children with the late infantile form of MLD presented between ages 6 and 25 (mean 17) months with a delay or deterioration in walking, followed by a general loss of abilities. There was severe handicap by age 3 years and death occurred between 5 months and 8 years after presentation. Neurological signs at the time of diagnosis were varied. Motor nerve conduction velocity was slowed in the 18 children tested. The disease became evident at a later age in 14 children. One boy presented at 13 years, while in the remainder there appeared to be two clinical patterns of the disease which could be termed (1) early juvenile or intermediate and (2) juvenile MLD. In 7 children with early juvenile or intermediate MLD a gait disorder developed between ages 4 and 6 (mean 5) years. This was accompanied in 4 children, and followed between 8 and 26 months later in the remaining 3, by loss of other abilities. Neurological signs were varied. Motor nerve conduction velocity was slowed in 2 of the 5 patients tested. Six children with juvenile MLD presented between ages 6 and 10 years with educational or behavioural difficulties. Motor disorders arose from 6 months to 4 years later. Neurological signs at the time of diagnosis, although mixed, were predominantly extrapyramidal and motor nerve conduction velocity was slowed in 2 of the 3 children tested. In the early juvenile form of MLD, progression of the disease was slower than in the late infantile form and death occurred between 31/2 and 18 years after presentation. Only one-third of patients had fits and these tended to be a late feature.

Rectal biopsy in the diagnosis of neurological disease in childhood

A surgical technique for taking a full thickness rectal biopsy for neurological diagnosis is described. The indications for, and results of 93 biopsies are reviewed. A definite neurological diagnosis was made in 38 (41 per cent). The usefulness of rectal biopsy is now largely confined to Batten's disease, which was found in 32 (34 per cent of the total). Alternatives and objections to rectal biopsy for neurological diagnosis are discussed. It is concluded that rectal biopsy is a safe and reliable procedure.

Reassessment of rectal approach to neuropathology in childhood: review of 307 biopsies over 11 years

A series of 93 rectal biopsies performed for diagnosis of suspected progressive neurometabolic disease between 1967 and 1973 is reviewed, and the results of this and of two previously published series totalling 307 biopsies are analysed. In G_M1 and G_M2 gangliosidosis, Batten's disease, and certain other neuronal storage diseases rectal biopsy is a reliable diagnostic alternative to brain biopsy. However, the need for biopsy has diminished with improvement in other diagnostic methods, particularly enzyme assay, the availability of which should determine the extent to which biopsy is used. It is suggested that rectal biopsy is necessary in the various forms of Batten's disease and in the neurovisceral storage disease with supranuclear ophthalmoplegia described by Neville et al. (1973). In certain diseases its use is unjustified, either because the result would be negative or because other less traumatic, reliable investigations are available. On rare occasions it is justifiable to use rectal biopsy either as an `excluding investigation' to exclude Batten's disease for certain in a healthy sib of a known case with this disorder or to detect the disease before onset of clinical symptoms. The need for a full thickness biopsy and for a full range of staining methods is emphasized. Without these the investigation cannot be expected to give diagnostic information and may be misleading, giving `false negative' results.

Late onset GM2-gangliosidosis. Clinical, pathological, and biochemical studies on 8 patients

Eight cases of late onset G_M2-gangliosidosis are described. 4 presented before the age of 2 years and 4 between 3½ and 10 years. Gait disturbance, intellectual deterioration, and fits were prominent features. Optic atrophy was seen at a late stage in 2 patients. An exaggerated startle reaction to sound and an unusual type of cherry red spot at the macula were seen for the first time in this condition. Pathological changes were similar to those described in Tay-Sachs disease. There was an increase in the amount of a ganglioside chromatographically identical with that found in Tay-Sachs disease. A partial deficiency of hexosaminidase A was found in 2 cases and a profound deficiency in 4. There was no correlation between the age of onset of symptoms and the degree of enzyme deficiency. The evidence presented is consistent with an autosomal recessive mode of inheritance.

SUBACUTE SCLEROSING (INCLUSION BODY) ENCEPHALITIS

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