Ciguatera and mannitol: experience with a new treatment regimen

Ciguatera is a distressing, hitherto-untreatable and not rare disease which results from the eating of ciguatoxin-contaminated fish from tropical and subtropical waters. We report here the results of a pilot study to assess the efficacy of mannitol therapy in ciguatera poisoning. Twelve adult patients (six men) have been treated, five of whom--who were ill acutely--experienced a significant benefit from this therapy, in three cases, with a hitherto-unexperienced dramatic reversal of symptoms. We conclude that an intravenous infusion of 1.0 g/kg of mannitol which is given over 45 minutes, after rehydration if required, can be of significant benefit to at least some acutely intoxicated victims. We postulate either a reduction of axonal oedema, or a scavenger effect, or both, as the mechanism of the beneficial effects of mannitol. Ciguatoxin is rich in hydroxyl groups, and causes microscopic oedema of neural tissue. If our conclusion of the beneficial effects of mannitol therapy is confirmed, this will offer the first effective therapy for acute phases of this disease, and has promise of preventing much long-term morbidity.

The origin and nature of stromal osteoclast-like multinucleated giant cells in breast carcinoma: implications for tumour osteolysis and macrophage biology

The origin and nature of osteoclast-like multinucleated giant cells (OMGCs), in extraskeletal neoplasms, is uncertain. The ultrastructure, antigenic phenotype and function of OMGCsm in a breast carcinoma were studied in order to clarify the relationship between OMGCs, osteoclasts and other cells of the mononuclear phagocyte system (MPS). OMGCs resorbed cortical bone in a manner similar to osteoclasts. However, unlike osteoclasts, OMGCs did not possess a ruffled border or clear zone, and expressed HLA-DR and Fc receptors and CD14, CD16, CD18 and CD11 (p150,95) antigens. In addition, OMGCs failed to respond morphologically to calcitonin and were directly stimulated by parathyroid hormone (PTH) to increase bone resorption. These findings suggest that OMGCs are a specific type of macrophage polykaryon distinct from both osteoclasts and other types of inflammatory polykaryon. Occasional smaller (20-25 microns) macrophage-like cells were also associated with resorption pits. Bone resorption by OMGCs isolated from the breast indicates that a cell of the MPS can be transplanted to a new tissue location and perform a highly specialised function appropriate to an MPS cell of that tissue (i.e. the osteoclast). PTH stimulation of bone resorption by OMGCs suggests that PTH or a PTH-like protein, may be involved in the bone resorption and consequent hypercalcaemia associated with metastatic breast cancer.

Long-term pulmonary sequelae of meconium aspiration syndrome

To determine the incidence of long-term sequelae after meconium aspiration syndrome (MAS), we studied 11 children who had MAS at age 8.2 +/- 0.2 years (mean +/- SD) and nine healthy control subjects with pulmonary function and exercise stress tests. The MAS children had evidence of mild airway obstruction, hyperinflation, and increased closing volumes in comparison with control values. During graded exercise stress tests on a treadmill, MAS children achieved normal maximal oxygen consumption and anaerobic threshold without a significant fall in arterial oxygen saturation or increase in CO2 tension. Exercise-induced bronchospasm occurred in four (36%) MAS subjects but in none of the control subjects. We conclude that children surviving MAS have long-term pulmonary sequelae, including airway obstruction, hyperinflation, elevated closing volumes, and airway hyperreactivity; yet they achieve normal aerobic capacity. These findings are similar, although less severe, than those after prematurity and bronchopulmonary dysplasia.

The immunohistology of synovial lining cells in normal and inflamed synovium

The immunohistology of synovial lining cells (SLCs) in normal and inflamed hyperplastic synovium was investigated using monoclonal antibodies directed against leucocyte common antigen (LCA) HLA-DR and other macrophage components. We found that some SLCs in normal synovium express LCA, HLA-DR, and monocyte/macrophage-associated antigens. The number of SLCs expressing these antigens is increased in hyperplastic osteoarthritic (OA) and rheumatoid (RA) synovium. Some SLCs which did not react for LCA or other macrophage markers but were positive for HLA-DR were also noted in normal synovium and some segments of hyperplastic OA synovium. SLCs which are positive for LCA, HLA-DR, and macrophage markers contribute to the intimal hyperplasia in RA where they account for the majority of SLCs in the synovial intima. In OA synovium, the distribution of SLCs showing this pattern of reactivity was less uniform with numerous SLCs which were positive for HLA-DR but negative for LCA and other macrophage markers also present in the synovial intima. These findings indicate that there are some SLCs of bone marrow origin in normal and hyperplastic synovium. They also suggest that recruitment of SLCs of marrow origin is important in the production of intimal hyperplasia in both RA and OA and that there is also a significant local proliferation of non-marrow derived SLCs in OA.

An anatomical study of cholinergic innervation in rat cerebral cortex

The cholinergic innervation of rat cerebral cortex was studied by immunohistochemical localization of choline acetyltransferase. Stained bipolar cells, fibers and terminals were found in all areas of cortex. The density of cholinergic terminals was similar in all cortical areas with the exception of entorhinal and olfactory cortex, which showed a marked increase in the number of stained terminals. A laminar distribution of cholinergic terminals was found in many cortical areas. In motor and most sensory areas, terminal density was high in layer 1 and upper layer 5, and lowest in layer 4. Visual cortex, in contrast to other cortical areas, was characterized by a dense band of innervation in layer 4. It has been known that the majority of cortical cholinergic structures derive from a projection to cortex from large, multipolar neurons in the basal forebrain, which stain heavily for choline acetyltransferase. In this study, stained fibers were observed to take three different pathways from basal forebrain to cortex. The first, confined to medial aspects of forebrain and cortex, was observed to originate in the septal area, from where fibers formed a discrete bundle, swinging forward around the rostral end of the corpus callosum, then travelling caudally in the cingulate bundle. The second was found to consist of fibers fanning out laterally from the area of the globus pallidus, travelling through the caudate, then continuing for various distances in the corpus callosum before finally turning into the cortex. A third pathway appeared to innervate olfactory and entorhinal cortex. Ibotenic acid injections were made in the area of the globus pallidus to study the effect of lesioning the lateral pathway on the cholinergic innervation in cortex. A major loss of choline acetyltransferase positive terminals was observed in neocortex, but retrosplenial, cingulate, entorhinal and olfactory cortex showed a normal density of cholinergic innervation. The borders separating areas with lesioned cholinergic input from non-lesioned areas were precise. The distribution of stained terminals remaining in cortical areas with lesioned basal forebrain innervation suggests that the basal forebrain projection to cerebral cortex, and not the intrinsic cortical cholinergic neurons, give rise to the laminar distribution of cholinergic terminals observed in normal cortex. To compare the relative densities of different cholinergic cortical systems, the distribution of choline acetyltransferase staining was compared with that of vasoactive intestinal polypeptide and substance P, which are co-localized in some choline acetyltransferase-positive neurons innervating cortex.

Immunohistology of rheumatoid nodules and rheumatoid synovium

The immunohistological features of rheumatoid nodules and rheumatoid synovium were examined using monoclonal and polyclonal antibodies raised against macrophages, HLA-DR, leucocyte common antigen, and immunoglobulin components. The palisading cells surrounding the necrotic centre of the rheumatoid nodule were shown to be HLA-DR positive leucocytes, mostly histiocytes. The inflammatory infiltrate associated with rheumatoid nodules showed many immunohistochemical similarities to that of rheumatoid synovium, including a preponderance of IgG positive plasma cells, and a similar number and microanatomical pattern of distribution of HLA-DR positive cells. The significance of these findings for the cellular immunopathology and aetiology of the rheumatoid lesion is discussed.

A monoclonal antibody (anti-L-35) which reacts with human osteoclasts and cells of the mononuclear phagocyte system

The immunohistochemical reactivity of a monoclonal antibody, anti-L-35, on a wide range of tissues is described. Anti-L-35 showed a high specificity for known and presumptive cells of the mononuclear phagocyte system including monocytes, sinus histiocytes, tangible body macrophages, interdigitating reticulum cells, Kupffer cells, alveolar macrophages, microglia, synoviocytes and Langerhans cells. Anti-L-35 also stained osteoclasts in fetal and adult bone including osteoclast-like giant cells of the giant-cell tumour of bone. Anti-L-35 did not react with any other cell type in the tissues screened apart from renal proximal tubular epithelium and megakaryocytes. This study has shown that L-35 is not restricted to activated T-cells, as previously reported, and provides further immunohistochemical evidence that monocytes, macrophages and osteoclasts contain common cellular antigens.

Immunocytochemical analysis of the human osteoclast: phenotypic relationship to other marrow-derived cells

The immunocytochemistry of the osteoclast, which is known to be derived from a circulating mononuclear precursor cell of bone marrow origin, is controversial. In this study, we have determined the antigenic phenotype of human osteoclasts in fetal and adult (Paget's disease, giant cell tumour of bone) specimens using a large number of monoclonal antibodies which react with granulocytes and mononuclear phagocytes. We have identified antibodies which reacted with human osteoclasts including CD13, CD15 and several groups of anti-macrophage antibodies. All the antibodies which reacted with osteoclasts are also known to react with monocytes or macrophages. Other marrow elements such as granulocytes, megakaryocytes and platelets were also commonly stained. Expression of myeloid and platelet antigens on osteoclasts shows that they are phenotypically related to these cells and is in keeping with the origin of osteoclast precursors from the pluripotential haemopoietic stem cell. Only a proportion of osteoclasts in fetal bone preparations were stained by CD15 antibodies, suggesting that subsets or different populations of osteoclasts, which can be identified by monoclonal antibodies, may be present in bone.

Localization of platelet antigens and fibrinogen on osteoclasts

The antigenic phenotype of the human osteoclast, which is known to be derived from a circulating mononuclear precursor cell of haemopoietic origin, is controversial. Recent studies have shown that macrophage as well as megakaryocyte/platelet antigens are expressed by osteoclasts. In this study, we have sought to define, by immunohistochemistry, the nature and possible function of platelet antigens expressed by human osteoclasts in foetal and adult bone specimens. Monoclonal antibodies to platelet glycoprotein IIIa (gpIIIa) and CD9 antibodies stained osteoclasts in all bone specimens examined. Fibrinogen was also localized to the osteoclast membrane in foetal bone imprints. In addition, we found that CD9 and gpIIIa antibodies reacted weakly with monocytes in buffy coat smears. Antibodies to factor 8 and glycoproteins Ib and IIb/IIIa did not react with osteoclasts. These results show that osteoclasts, monocytes, macrophages, megakaryocytes and platelets possess common antigens and that fibrinogen is present on the surface of osteoclasts. By analogy with platelets, CD9 and gpIIIa may play a role in fibrinogen binding by osteoclasts. Possible mechanisms by which platelet antigens and fibrinogen binding could affect osteoclast function are proposed.

Removal of observer variability from the determination of the volume of isoflow

The initial attractiveness of the volume of isoflow (VisoV) as an index of early small airways dysfunction has faded, perhaps because of VisoV's high variability, a significant part of which is contributed by the observer. We suggest here that the observer variability can be removed by filtering the flow data in the reciprocal volume domain, by using a modified foreign gas mixture in which some of the helium is replaced by neon, and by reading VisoV from a plot of density dependence vs. lung inflation. Support for these suggestions is drawn from both model simulations and experiments. Model simulations suggested that VisoV would be increased by the substitution of neon for some of the helium in the usual helium-oxygen (Helox) mixture. This was confirmed in tests on matched groups of normal and asymptomatic asthmatic children. The inclusion of 20% neon (Heneox20) was found to reduce the coefficient of variation in the mean value of VisoV in both groups of subjects. An interesting result of this test was that VisoV using Heneox20 was significantly higher in the asthmatic group than in the normal group, whereas VisoV using Helox was not. The results for density dependence (DD) between the 2 groups were not significantly different using Heneox20 but were using Helox. Plots of DD (derived from heavily filtered flow curves) vs. lung inflation showed an unambiguous value for VisoV.

Leucocyte common antigen is present on osteoclasts

Using a large panel of monoclonal antibodies which recognize the leucocyte common antigen (LCA), the presence of LCA on osteoclasts in both fetal and adult human bone specimens has been determined by immunohistochemistry. LCA is evident on the surface of fetal human osteoclasts in bone imprints and cryostat sections. LCA was also found on osteoclasts in specimens of fixed, decalcified osteoarthritic bone. The intensity and pattern of osteoclast reactivity were similar to those of foreign-body type macrophage polykaryons in inflammatory lesions. These results favour derivation of osteoclasts and their precursors from the multipotential haemopoietic stem cell which produces peripheral blood leucocytes and argues against their origin from a separate stem cell.

Effect of decalcification agents on immunoreactivity of cellular antigens

The effects of several strong acids, weak acids, a proprietary decalcifier, and edetic acid on the immunohistochemical staining of cryostat and fixed paraffin embedded sections of tissue from a variety of normal and pathological calcified and uncalcified specimens were studied. Even decalcification in strong acids (HCl, HN03, 5% trichloracetic acid, HCl-edetic acid did not diminish the reactivity of many useful antigens (including leucocyte common antigen, intermediate filaments, S100 protein and epithelial membrane antigen). Weaker acids (formic acid, acetic acid) and edetic acid decalcified more slowly and generally showed greater preservation of antigenic reactivity with better morphology and staining quality. Trichloracetic acid was also useful as a quick one step fixation and decalcifying agent for both cryostat and routinely processed sections. Knowledge of the preservation of antigenic reactivity in decalcified tissue will be useful in the diagnosis of tumours of uncertain histogenesis and origin which affect calcified tissues.