Ultrastructural pathology and cytochemical investigations of L-2-chloropropionic acid-induced neurointoxication of the rat cerebellum.

The objectives of the studies described were to assess the ultrastructural neuropathology, blood-brain barrier (BBB) integrity and calcium status of the cerebellum of rats following a single dose of 750 mg.kg-1 L-2-chloropropionic acid (L-2-CPA). The first indications of intoxication appeared at 36 h when condensation of many granule cells associated with Purkinje cell degeneration and marked astroglial swelling were observed. Some electron-lucent granule cells were also noted lying amongst these condensed forms. Condensed granule cells had swollen, electron-lucent mitochondria, dilated Golgi apparatus and nuclear crenation. Occasionally, areas of the granule cell necrosis were also present at this time. Granule cell condensation probably represents a preliminary and irreversible stage in an excitotoxic process that leads to necrosis. At 48 and 72 h, most granule cells were necrotic, and occasionally, extravasation of both erythrocytes and leucocytes into the expanded extravascular space was observed. Evaluation of the BBB by ultrastructural cytochemical visualisation of horseradish peroxidase injected i.v. 2 min before killing by perfusion fixation showed substantial leakage. At 36 h post-dose, ultrastructural calcium localisation using oxalate/pyroantimonate precipitation demonstrated a substantial increase in calcium pyroantimonate precipitate in mitochondria and other membranous cytoplasmic organelles (especially the Golgi apparatus) in condensed granule cells, but with little in their nuclei. However, their immediate neighbours (of ostensibly normal ultrastructural appearances) contained greater amounts of intranuclear precipitate. Swollen astroglial cells (especially the Bergmann glia) contained considerable quantities of precipitate. A possible excitotoxic mechanism via L-2-CPA-induced NMDA receptor agonism leading to overwhelming calcium influx and disruption of cellular calcium homeostasis is proposed.

Assessment of the labeling index of cohorts of the anterior pituitary cell population in phenobarbital-treated male rats by a double immunohistochemical technique for bromodeoxyuridine and pituitary hormones.

A previous study demonstrated that administration of phenobarbital for up to 7 days to male AP Wistar rats caused alterations in labeling indices (LIs) of several different tissues as determined by immunohistochemical visualization of bromodeoxyuridine (BrdU) incorporation into S-phase nuclei. The pivotal role of the pituitary gland in the function of the endocrine system and changes in circulating hormone levels that result from administration of xenobiotics prompted our consideration of the possible changes in LIs of individual cohorts of the anterior pituitary cell population that may occur as a specific functional adaptation during phenobarbital administration. We evaluated the LIs of individual anterior pituitary cell cohorts by modifying a double immunohistochemical staining method for bromodeoxyuridine and pituitary hormones using a sequential peroxidase-anti-peroxidase (PAP)/alkaline phosphatase-anti-alkaline phosphatase (APAAP) method employing diaminobenzidine and New Fuchsin chromogens, respectively. The method was robust and reproducible. Differences were noted in individual anterior pituitary cohort LIs between control and phenobarbital-treated groups, although no statistically significant difference was evident. We conclude that no detectable effects on individual cohort LIs were induced by treatment with phenobarbital for up to 7 days and that any functional adaptation to treatment was associated with increased hormone release. We believe that the visualization, identification, and quantitation of replicating cells in specific hormone-positive cohorts of the anterior pituitary cell population provide opportunities for understanding the influence of xenobiotics and disease processes on pituitary function.

Assessment of the labelling index of cohorts of the pancreatic islet cell population in phenobarbitone-treated male rats using a double immunohistochemical technique for 5-bromo-2'-deoxyuridine and pancreatic hormones.

A previous study demonstrated that administration of phenobarbitone to male AP Wistar rats for up to 7 days caused alterations in labelling indices (LIs) in several different tissues (including a reduction of the endocrine pancreas population LI) as determined by immunohistochemical visualisation of 5-bromo-2'-deoxyuridine (BrdU) incorporation into S-phase nuclei. The primary objective of this study was to determine whether treatment with phenorbarbitone influenced the replicative states of specific cohorts of the islet (of Langerhans) cell population or generated a uniform depression of LI. Quantitation of the LIs of individual islet cell cohorts was achieved by utilisation of a dual immunohistochemical staining method for BrdU and islet hormones (insulin, glucagon and somatostatin) using a sequential peroxidase anti-peroxidase (PAP)/alkaline phosphatase anti-alkaline phosphatase (APAAP) method employing diaminobenzidine and New Fuchsin chromogens, respectively. We observed reductions, increases and no change in LIs of insulin-, glucagon- and somatostatin-positive cells, respectively. We conclude that the decreased LI of the insulin-positive cohort was not countered entirely by the LI increase in the glucagon-positive cohort due to the larger size of the former. Furthermore, the effects of phenobarbitone treatment are not manifested generally in the islet cell population but in the insulin- and glucagon-positive cohorts only. The causation of these effects is unknown but is likely to be due to enhanced carbohydrate and hormone metabolism. We believe that the visualisation and quantitation of replicating cells in specific hormone-positive cohorts of the islet cell population provide opportunities for understanding the influence of xenobiotics and disease processes on pancreatic function.

Pathological and morphometric assessment of testicular parameters in patients with metastatic prostate cancer following treatment with either the antiandrogen Casodex (ZM176,334) or bilateral orchidectomy.

Casodex is an orally active non-steroidal antiandrogen that is highly selective for androgen receptors in animals and man. It is indicated for the non-surgical treatment of advanced prostate cancer in man. The present open controlled study in 13 Casodex-treated and 21 orchidectomy-alone (control) patients addressed the hypothesis that chronic administration of antiandrogens will result in Leydig cell hyperplasia as a result of feedback inhibition of the pituitary resulting in increased luteinising hormone (LH) stimulation of Leydig cells. Although Casodex has been shown to produce a moderate rise in circulating plasma testosterone concentration on chronic treatment in prostate cancer patients, a controlled histopathological and morphometric assessment of the testis following orchidectomy in relapsed Casodex patients showed no effect on Leydig cell populations compared with an orchidectomy alone (control) group. No evidence for induction of Leydig cell hypertrophy or hyperplasia as a result of chronic oral administration of 50 mg Casodex daily was obtained in this study.

The morphological and immunohistochemical analysis of renal biopsies by light and electron microscopy using a single processing method.

A methodology is described in which a number of well-established research techniques are brought together to enable the complete diagnostic analysis of a renal biopsy on a single piece of tissue. By embedding the biopsy in the acrylic resin LR White, unsupported sections of which are stable in the electron beam, light and electron microscopy and immunocytochemistry become feasible on sections from the same block. The biopsy is glutaraldehyde fixed but post-fixation in osmium tetroxide, which is often deleterious to antigen preservation, is omitted. Extraction in organic solvents and resin monomer is minimized by rapidly infiltrating the tissue from 70% ethanol and polymerizing the resin catalytically at 0 degrees C. Semithin sections can be stained with haematoxylin and eosin, Toluidine Blue or methenamine silver, giving results similar or superior to those obtained from paraffin sections. Thin sections show that the standard of morphological preservation is similar to that seen using epoxide sections even though the kidney is unosmicated. The tissue retains a high level of antigen reactivity, which, in the limited number of cases so far examined, has paralleled or exceeded that demonstrated by conventional immunofluorescence on frozen sections.