Surgical smoke - a health hazard in the operating theatre: a study to quantify exposure and a survey of the use of smoke extractor systems in UK plastic surgery units

Surgeons and operating theatre personnel are routinely exposed to the surgical smoke plume generated through thermal tissue destruction. This represents a significant chemical and biological hazard and has been shown to be as mutagenic as cigarette smoke. It has previously been reported that ablation of 1 g of tissue produces a smoke plume with an equivalent mutagenicity to six unfiltered cigarettes. We studied six human and 78 porcine tissue samples to find the mass of tissue ablated during 5 min of monopolar diathermy. The total daily duration of diathermy use in a plastic surgery theatre was electronically recorded over a two-month period. On average the smoke produced daily was equivalent to 27-30 cigarettes. Our survey of smoke extractor use in UK plastic surgery units revealed that only 66% of units had these devices available. The Health and Safety Executive recommend specialist smoke extractor use, however they are not universally utilised. Surgical smoke inhalation is an occupational hazard in the operating department. Our study provides data to quantify this exposure. We hope this evidence can be used together with current legislation to make the use of surgical smoke extractors mandatory to protect all personnel in the operating theatre.

An association of multiple well differentiated liposarcomas, lipomatous tissue and hereditary retinoblastoma

Well differentiated liposarcoma (atypical lipomatous tumour) is a low grade tumour, with no metastatic potential unless dedifferentiation supervenes. When superficial, it recurs locally only occasionally after marginal excision. We present a patient in whom bilateral childhood retinoblastoma was followed by later development of massive confluent areas of low grade liposarcoma and lipomatous tissue affecting the upper extremities and trunk. We discuss the role of mutations in the retinoblastoma gene (RB1) in linking these conditions and demonstrate the surgical management of an extremely unusual and challenging case.

Pyoderma gangrenosum: a report of a rare complication after knee arthroplasty requiring muscle flap cover supplemented by negative pressure therapy and hyperbaric oxygen

Pyoderma gangrenosum (PG) is rare ulcerating skin condition easily confused with wound infection following surgery. We report a complicated case of PG following knee arthroplasty where delayed diagnosis and repeated debridements lead to significant tissue loss. Successful reconstruction was achieved with a muscle flap, but subsequent reactivation of PG and superadded infection placed both the reconstruction and patient's life at risk. Prolonged combined use of negative pressure therapy (NPT), immunosuppression and hyperbaric oxygen (HBO) was successfully used to reduce the wound size, enhance wound granulation, promote re-epithelialisation, and provide pain relief. There is little or no published literature on these treatment modalities for the management of PG, with only one reported case using both NPT and HBO for PG (not following knee arthroplasty). More studies are necessary to determine the role of both modalities in the management of pathergy in large and complex wounds and the rare nature of this complication following knee arthroplasty explains the lack of evidence-based guidance. In conclusion, we suggest a surgical algorithm. This is the first report of PG following knee arthroplasty with the use of both NPT and HBO in order to achieve soft tissue coverage.

Pyoderma gangrenosum: a report of a rare complication after knee arthroplasty requiring muscle flap cover supplemented by negative pressure therapy and hyperbaric oxygen

Pyoderma gangrenosum (PG) is rare ulcerating skin condition easily confused with wound infection following surgery. We report a complicated case of PG following knee arthroplasty where delayed diagnosis and repeated debridements lead to significant tissue loss. Successful reconstruction was achieved with a muscle flap, but subsequent reactivation of PG and superadded infection placed both the reconstruction and patient's life at risk. Prolonged combined use of negative pressure therapy (NPT), immunosuppression and hyperbaric oxygen (HBO) was successfully used to reduce the wound size, enhance wound granulation, promote re-epithelialisation, and provide pain relief. There is little or no published literature on these treatment modalities for the management of PG, with only one reported case using both NPT and HBO for PG (not following knee arthroplasty). More studies are necessary to determine the role of both modalities in the management of pathergy in large and complex wounds and the rare nature of this complication following knee arthroplasty explains the lack of evidence-based guidance. In conclusion, we suggest a surgical algorithm. This is the first report of PG following knee arthroplasty with the use of both NPT and HBO in order to achieve soft tissue coverage.

Aplasia cutis congenita. A case of scalp defect repair using two opposing bipedicled local flaps

Aplasia cutis congenita is a rare congenital condition characterised by the absence of some or all layers of the skin. It may also be associated with absence of underlying muscle and bone. Where dura is exposed there exists a risk of ulceration and haemorrhage and thus primary closure is indicated. We report a case of cutis aplasia successfully closed with opposing bipedicled flaps. To our knowledge this is a novel approach which offers a simple safe technique that can be applied in the neonate.

Neurotized Free Muscle Flaps can Produce MRI Changes Mimicking Tumour Recurrence

Soft tissue sarcomas are investigated by magnetic resonance imaging (MRI) both for initial staging and follow-up. We describe the presence of increased signal on T2-weighted images caused by a neurotized muscle flap following reconstructive surgery. This raised concern about possible sarcoma recurrence that was not clinically evident. On post-operative imaging of sarcomas the presence of recurrent tumour is indicated by a mass and high signal intensity on T2-weighted images. However, high signal changes in skeletal muscle on T2-weighted images are not specific. In this case, the free functioning muscle transfer with neurotization of the flap mimicked recurrence on MR scan. High signal intensity on T2-weighted images in muscle is an indication of either a physiological change or a pathological condition and must be taken in context of the clinical picture.

Extranodal lymphomas presenting as soft tissue sarcomas to a sarcoma service over a two-year period

Non-Hodgkin's lymphoma usually presents with lymphadenopathy at multiple sites but can also involve any part of the musculoskeletal system. Occasionally the presentation is with a soft tissue mass. The presentation of large, superficial lymphomatous masses is similar both clinically and radiologically to that of soft tissue sarcomas. The six cases of lymphoma presenting to the Exeter Sarcoma Service as suspected soft tissue sarcomas, over a two-year period (2002-2004), are presented. We describe the clinical and imaging characteristics of these tumours and their subsequent management. Our cases showed variability in presentation. Only one of the six cases presented with pain and one with tenderness. Four of the cases had no lymphadenopathy and the other two had lymphadenopathy restricted to one nodal basin. Overlying soft tissue swelling occurred in four cases and in distal limb swelling beyond the mass in one case. Radiologically, lymphomas are known to be likely to exhibit confluent lymphadenopathy that is rare in patients with soft tissue sarcoma. Confluent lymphadenopathy was demonstrated in only one case of this series of patients. It is thought that lymphomas infiltrate across anatomical fascial planes more readily than sarcomas and in four of our six cases this feature was present. Clinical history, examination and MRI are insufficient to differentiate between soft tissue sarcoma and lymphoma and the importance of obtaining a pathological diagnosis prior to surgery is clear. It is crucial to differentiate lymphoma from sarcoma in order to avoid unnecessary excisional procedures in lymphoma patients.

Biphasic solitary fibrous tumour: a report of two cases with epithelioid features

We present two cases of solitary fibrous tumour (SFT) showing biphasic morphology with a spectrum of malignant epithelioid components. Slides prepared from formalin-fixed and paraffin-embedded tissue from both cases were stained with haematoxylin and eosin and by immunohistochemistry. Interphase fluorescent in situ hybridisation studies were performed in both cases using paraffin-embedded tissue to look for the t(X;18) translocation, thereby to exclude synovial sarcoma. Both cases showed biphasic morphology with some areas having typical benign spindled SFT morphology (including CD34 expression) and other areas having a malignant epithelioid appearance. In one of the cases, the epithelioid area, which was well circumscribed and showed packeting of cell groups, demonstrated expression of cytokeratin and epithelial cadherin but not of CD34. In the second case, the immunophenotype of the epithelioid component was similar to that of the benign SFT component. These findings suggest that epithelioid change in SFT shows a range of differentiation at one end, similar to that of a standard SFT, and at the other end, possibly acquiring epithelial characteristics.

CD44 is involved in selective leucocyte extravasation during inflammatory central nervous system disease

Clinical signs of experimental autoimmune encephalomyelitis (EAE) are associated with the selective recruitment of CD4+ memory (CD45RBlow CD44high) T cells into the central nervous system (CNS). However, we have found that many of these recently recruited memory cells are CD44low, suggesting that the CD44 antigen may be involved in, and transiently lost during, the extravasation process. Indeed, administration of a CD44-specific antibody (IM7.8.1) induced leucocyte CD44 shedding and both prevented the development and ameliorated the severity of established EAE by inhibiting mononuclear cell infiltration into the CNS. Trafficking of cells into lymph nodes, however, a property mainly of naïve cells, was essentially unaffected. In contrast, treatment with antibody to very late activation antigen-4 (VLA-4) prevented homing to both the CNS and to lymph nodes. This study contests previous reports that dismissed a role for CD44 in inflammation of the CNS and, coupled with observations in murine dermatitis and arthritis, suggests that CD44 is involved in the homing of primed lymphocytes to sites of inflammation. CD44 should therefore be considered a target for immunotherapy of T-cell-mediated inflammatory diseases, such as multiple sclerosis.

Local gene therapy with CTLA4-immunoglobulin fusion protein in experimental allergic encephalomyelitis

It has been reported previously that the induction phase of experimental allergic encephalomyelitis (EAE) is highly sensitive to systemic blockade of stimulation via MHC class II molecules and co-stimulation via the CD28:CD80/CD86 pathways. In contrast, the effector phases of EAE were relatively unaffected by similar treatments using MHC class II antigen (Ag)-specific mAb and cytotoxic T lymphocyte antigen (CTLA)4-Ig fusion proteins in some studies. This has been attributed to different sensitivities of effector cell function or the poor penetrance of inhibitory proteins into the central nervous system (CNS). To examine this question further, MHC class II Ag-specific mAb and CTLA4-Ig were delivered directly into the CNS following EAE induction, and both were found to inhibit disease. While it was found that systemic administration of mouse CTLA4-Ig could also inhibit the progression of effector immune responses when administered shortly before or during clinical disease, these were significantly more active when delivered directly into the CNS, which probably involved an action on both CD28 ligands, CD80 and CD86. Although mouse CTLA4-human Ig was therapeutically less efficient than mouse CTLA4-mouse Ig protein, probably due to the enhanced immunogenicity and lower functional activity, gene delivery of CTLA4-human Ig into the CNS using a non-replicating adenoviral vector was more effective than a single injection of CTLA4-human Ig protein. Gene delivery significantly ameliorated the development of EAE, without necessarily inhibiting unrelated peripheral immune responsiveness. Local gene delivery of CTLA4-Ig may thus be an important target for immunotherapy of human autoimmune conditions such as multiple sclerosis.

Optic neuritis in chronic relapsing experimental allergic encephalomyelitis in Biozzi ABH mice: demyelination and fast axonal transport changes in disease

The encephalitogenicity of optic nerve tissue was demonstrated in Biozzi ABH (H-2(dq1)) mice. Acute experimental allergic encephalomyelitis (EAE) occurred in 11/14 animals and 4/5 exhibited relapse. The involvement of the optic nerve in spinal cord homogenate induced chronic relapsing EAE (CREAE) was demonstrated by mononuclear cell infiltration and myelin degradation in the optic nerve prior to and during clinical disease. During the relapse phase gross pathological assessment revealed swollen and translucent plaques on the optic nerves. Advanced lesions showed widespread demyelination, astrocytic gliosis and fibrotic changes of the blood vessels. Physiologically, the fast axonal transport of proteins from the retina to the optic nerve and superior colliculus was significantly decreased during relapse. The association of inflammation and demyelination with physiological deficit in the optic nerve highlights the usefulness of this model in the study of multiple sclerosis in which acute monosymptomatic unilateral optic neuritis is a common manifestation. Furthermore, the novel induction of CREAE with optic nerve homogenate suggests that optic neuritis is a common significant role in the pathophysiology and progression of neurological disease in CREAE which may be relevant to studies of optic neuritis in multiple sclerosis.

Regulation of chronic relapsing experimental allergic encephalomyelitis by endogenous and exogenous glucocorticoids

Expression, development and resolution of the acute form of experimental allergic encephalomyelitis (EAE), typically induced in the highly susceptible Lewis rat, are closely regulated by endogenous corticosteroids. Administration of synthetic glucocorticoids also efficiently controls the manifestation of disease. The pivotal role played by the corticosteroids in modifying the induction and progression of EAE is further emphasised by a reversal of corticoid-mediated effects through adrenalectomy or treatment with the steroid receptor antagonist RU486 (mifepristone). Chronic relapsing EAE (CREAE) is characterised by acute symptoms, periods of remission and re-emergence of disease. The mechanisms governing the development of CREAE are unclear, but may require the regulatory influence of endogenous glucocorticoids. The current study has monitored circulating corticosteroids throughout the course of CREAE in the Biozzi ABH mouse and found that major fluctuations in systemic levels coincide with the relapsing-remitting phases of the disease. Furthermore, increasing circulating adrenocorticoids through administration of the steroidal compound dexamethasone markedly suppresses the occurrence of acute signs. The importance of the glucocorticoids in controlling CREAE is again highlighted by the intensification of symptoms and reduction in the survival rate of inoculated mice receiving RU486 prior to and during the acute phase of disease. The data reinforce the amelioratory actions of exogenous and naturally occurring glucocorticoids in the pathogenesis of EAE and extend earlier observations in the monophasic disease by demonstrating corticosteroid-dependent effects in a relapsing-remitting mouse model.

Polygenic control of experimental allergic encephalomyelitis in Biozzi ABH and BALB/c mice

Experimental allergic encephalomyelitis (EAE) is a chronic inflammatory disease of the central nervous system (CNS), with many similarities to multiple sclerosis (MS). Susceptibility to EAE is under genetic control of both the major histocompatibility complex (MHC) and unknown non-MHC gene products. This study uses a selective cross between EAE-susceptible ABH and low responder BALB/c mice, where disease is dominant and affects female mice significantly more than males. In a genome screen using microsatellite markers, linkage analysis suggests that genes encoded on chromosomes 4, 8, 10, 11, 12 and 17 contribute to the development of EAE (p < 0.05), although none of these putative EAE loci fulfilled the criteria for significant linkage. Interestingly, genotype frequency showed significant deviation from the expected random distribution of alleles on chromosomes 4, 8 and 17, (p < 0.001), with 32% of mice developing disease, exhibiting all 3 alleles (p < 0.001). This may indicate complex interactions amongst gene products in the EAE phenotype. This and other recent studies in different mouse strains underlies that EAE is a complex polygenic trait and may provide clues to the genetic mechanisms involved in autoimmune diseases such as multiple sclerosis.

Encephalitogenic epitopes of myelin basic protein, proteolipid protein, myelin oligodendrocyte glycoprotein for experimental allergic encephalomyelitis induction in Biozzi ABH (H-2Ag7) mice share an amino acid motif

Myelin basic protein (MBP) and synthetic MBP peptides were screened for their ability to induce experimental allergic encephalomyelitis in Biozzi ABH (H-2Ag7) mice. In contrast to the failure of native MBP to induce experimental allergic encephalomyelitis, the use of overlapping MBP peptides revealed epitopes within MBP 12-26 and MBP 21-35, which induced mild disease. In comparison with disease induced by spinal cord homogenate or peptides of myelin oligodendrocyte glycoprotein (MOG) or proteolipid protein (PLP), the low incidence indicates that, at least in ABH mice, MBP is a minor encephalitogen. However, the data suggest the presence of a peptide core between MBP 21-26 (HARHGF), which contains similar elements to the previously defined encephalitogenic MOG 1-22 and PLP 56-70 peptides. The fine specificity of these epitopes was further investigated using frame-shifted peptides, which indicated cores between MOG 9-15 (GYPIRAL) and PLP 62-68 (NVIHAFQ). Based on these pathogenic peptides, a putative H-2Ag7 binding motif is suggested that contains a series of hydrophobic, basic, small, and large hydrophobic residues within a 6 to 7 amino acid core. The core and particular importance of these four residues in PLP 56-70 was confirmed in vitro using amino acid substitution studies. These findings support many of the predictions made by computer modeling of peptide:H-2Ag7 interactions. This may have relevance in the design of strategies in the treatment of experimental autoimmune diseases in animals that express this haplotype.

Encephalitogenic epitopes of myelin basic protein, proteolipid protein, myelin oligodendrocyte glycoprotein for experimental allergic encephalomyelitis induction in Biozzi ABH (H-2Ag7) mice share an amino acid motif

Myelin basic protein (MBP) and synthetic MBP peptides were screened for their ability to induce experimental allergic encephalomyelitis in Biozzi ABH (H-2Ag7) mice. In contrast to the failure of native MBP to induce experimental allergic encephalomyelitis, the use of overlapping MBP peptides revealed epitopes within MBP 12-26 and MBP 21-35, which induced mild disease. In comparison with disease induced by spinal cord homogenate or peptides of myelin oligodendrocyte glycoprotein (MOG) or proteolipid protein (PLP), the low incidence indicates that, at least in ABH mice, MBP is a minor encephalitogen. However, the data suggest the presence of a peptide core between MBP 21-26 (HARHGF), which contains similar elements to the previously defined encephalitogenic MOG 1-22 and PLP 56-70 peptides. The fine specificity of these epitopes was further investigated using frame-shifted peptides, which indicated cores between MOG 9-15 (GYPIRAL) and PLP 62-68 (NVIHAFQ). Based on these pathogenic peptides, a putative H-2Ag7 binding motif is suggested that contains a series of hydrophobic, basic, small, and large hydrophobic residues within a 6 to 7 amino acid core. The core and particular importance of these four residues in PLP 56-70 was confirmed in vitro using amino acid substitution studies. These findings support many of the predictions made by computer modeling of peptide:H-2Ag7 interactions. This may have relevance in the design of strategies in the treatment of experimental autoimmune diseases in animals that express this haplotype.

Care-giver evaluation of anti-gastroesophageal reflux procedures in neurologically impaired children: what is the real-life outcome?

Although the pediatric surgical literature is replete with reports of the success of operations for gastroesophageal reflux, postoperative complications are being reported with increasing frequency for the neurologically impaired subpopulation. Because a large portion of a care-giver's life is involved in attending to a neurologically impaired child, parental satisfaction with the outcome of these operations should be an important consideration when the use of such procedures is contemplated. The purpose of the present study was to assess the impact of antireflux operations with respect to care-giver opinions regarding the procedure. The authors retrospectively reviewed 25 charts (of 13 girls and 12 boys; age range, 3 months to 18 years) and documented (through survey results) perceived child well-being, objective care requirements, and overall care-giver satisfaction with the procedure. Results indicate there was significant improvement in feeding indexes, care-giver perception of the child's comfort, and quality of life postoperatively. Moreover, there was significant improvement in the care-givers' attitudes regarding their child, including the level of frustration in caring for the child, and the parents' overall quality of life. Care-givers also believed that the operation's result was about or better than what they had expected. In conclusion, the study documents care-giver satisfaction with antireflux procedures. Postoperatively, child care is easier and the quality of time spent with the child is better. The impression of better quality of life postoperatively for a neurologically impaired child may be the greatest success in this sometimes frustrating endeavor.

Genetic analysis of experimental allergic encephalomyelitis in mice

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease of the central nervous system that exhibits many pathologic similarities with multiple sclerosis. While products of the MHC are known to control the development of EAE, it is clear that non-MHC products also influence susceptibility. The chromosomal locations of these were investigated in selective crosses between MHC class II-compatible, EAE-susceptible Biozzi ABH, and low responder nonobese diabetic (NOD) mice. The disease was dominant and highly influenced by gender in the backcross one (BC1) generation. Female mice were significantly more susceptible than male mice. Segregation of disease frequency of female animals in this cross suggested that EAE was controlled by a major locus. Although microsatellite-based exclusion mapping indicated that a number of regions on chromosomes 5, 6, 7, 8, 9, 10, 11, 12, 13, and 18 showed evidence of linkage (p &lt; 0.05) compared with expected random distributions of alleles, disease susceptibility was most strongly linked (p &lt; 0.001) to chromosome 7. However, by selectively analyzing animals that were either severely affected or almost normal, additional susceptibility loci were mapped on chromosomes 18 and 11 that were linked (p &lt; 0.001) to resistance and the development of severe disease, respectively. The data indicate a major locus on chromosome 7, affecting initiation and severity of EAE that is probably modified by several other unlinked loci. These localizations may provide candidate loci for the analysis of human autoimmune-demyelinating disease.

Genetic analysis of experimental allergic encephalomyelitis in mice

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease of the central nervous system that exhibits many pathologic similarities with multiple sclerosis. While products of the MHC are known to control the development of EAE, it is clear that non-MHC products also influence susceptibility. The chromosomal locations of these were investigated in selective crosses between MHC class II-compatible, EAE-susceptible Biozzi ABH, and low responder nonobese diabetic (NOD) mice. The disease was dominant and highly influenced by gender in the backcross one (BC1) generation. Female mice were significantly more susceptible than male mice. Segregation of disease frequency of female animals in this cross suggested that EAE was controlled by a major locus. Although microsatellite-based exclusion mapping indicated that a number of regions on chromosomes 5, 6, 7, 8, 9, 10, 11, 12, 13, and 18 showed evidence of linkage (p < 0.05) compared with expected random distributions of alleles, disease susceptibility was most strongly linked (p < 0.001) to chromosome 7. However, by selectively analyzing animals that were either severely affected or almost normal, additional susceptibility loci were mapped on chromosomes 18 and 11 that were linked (p < 0.001) to resistance and the development of severe disease, respectively. The data indicate a major locus on chromosome 7, affecting initiation and severity of EAE that is probably modified by several other unlinked loci. These localizations may provide candidate loci for the analysis of human autoimmune-demyelinating disease.

Experimental encephalomyelitis modulates inositol and taurine in the spinal cord of Biozzi mice

In this high resolution magnetic resonance spectroscopic study of experimental allergic encephalomyelitis (EAE) and Semliki Forest virus (SFV) infection of the Biozzi AB/H mouse, marked increases in the initially low levels of N-trimethyl compounds in the spinal cord were observed during probable demyelinating episodes. There was also a pronounced and reproducible modulation of the levels of taurine and myo-inositol during acute and again during chronic relapsing EAE. The ratio of N-acetyl-aspartate to creatine in the spinal cord of mice infected with the mutant M9 strain of SFV decreased to approximately 70% of that seen in normal mice.

Control of established experimental allergic encephalomyelitis by inhibition of tumor necrosis factor (TNF) activity within the central nervous system using monoclonal antibodies and TNF receptor-immunoglobulin fusion proteins

Tumor necrosis factor (TNF) activity was inhibited during the development of actively-induced, chronic relapsing experimental allergic encephalomyelitis (CREAE) in Biozzi AB/H mice, using a mouse TNF-specific (TN3.19.12) antibody and bivalent human p55 and p75 TNF receptor-immunoglobulin (TNFR-Ig) fusion proteins. The development of disease could be inhibited when repeated doses of antibody were administered prior to the anticipated onset. It has now also been shown that a therapeutic effect is evident even when antibody is administered after the onset of clinical signs, further indicating an important role for TNF in pathogenic effector mechanisms in CREAE. Although biologically-active TNF was not detected in the circulation, TNF-alpha was detected in lesions within the central nervous system (CNS). This suggested that the CNS may be the main site for TNF-specific immunomodulation and was supported by the observation that intracranial injection was significantly more potent than that administered systemically, for both antibody and TNFR-Ig fusion proteins. The fusion proteins were as effective as antibody at doses 10-100-fold lower than that used for antibody, reflecting their higher neutralizing capacity in vitro. Although treatment was not curative and relapse inevitably occurred in this model if treatment was not sustained, the data indicate that anti-TNF immunotherapy, especially within the CNS, can inhibit CREAE and may, therefore, be useful in the control of human neuroimmunological diseases.

Control of immune-mediated disease of the central nervous system with monoclonal (CD4-specific) antibodies

Chronic relapsing experimental allergic encephalomyelitis (CREAE) was induced in Biozzi AB/H (H-2dq1) mice by active sensitization with spinal cord antigens. A single i.p. injection of CD8-depleting (YTS169.4) monoclonal antibody (mAb) failed to affect the clinical course of CREAE when administered prior to and during the onset of both the initial clinical and subsequent relapse phase of the disease. By contrast similar treatment with both CD4-depleting (YTS191.1) or CD4-blocking/non-depleting (YTS177.9) mAb significantly inhibited disease progression. Treatment shortly before the anticipated onset of clinical EAE prevented the subsequent development of disease, although disease could be provoked following antigen-rechallenge. In contrast, treatment with these antibodies during post-acute remission phase mainly served to delay the incidence of relapse. This suggests that, unless tolerance can be re-induced, treatment of ongoing neuroimmunological disease will require 'pulse' therapy and thus potentiate the problems of long-term immunosuppresion. Despite the findings that CD4-specific antibodies can rapidly reverse overt clinical disease shortly after the onset of disease exacerbation, once neurological dysfunction becomes established anti-CD4 treatment fails to improve the animals clinically, possibly due to the inability to rapidly reverse established demyelination. Although this study does not exclude the potential central action of the injected mAb, the failure to significantly dissociate therapeutic benefit between mAb administered directly into the CNS and that given systemically suggests that a major action of these agents is probably by selectively removing T cells in the peripheral T cell pool.

Isolation and characterization of cells infiltrating the spinal cord during the course of chronic relapsing experimental allergic encephalomyelitis in the Biozzi AB/H mouse

A novel method for the isolation of leukocytes from the spinal cords of mice during chronic relapsing experimental allergic encephalomyelitis (CREAE) was developed using discontinuous density gradients. Immunostaining of these cells, together with spinal cord sections and peripheral blood leukocytes, with a panel of monoclonal antibodies enabled a detailed profile of the kinetics and cell phenotype during CREAE to be developed. Overall, the kinetics of cell accumulation within the spinal cord correlated with disease severity. The number of cells increased from an average of 5 x 10(4) in unimmunized animals to 40 x 10(4) in paralysed animals during the initial disease episode. The cell numbers rapidly declined with clinical remission (6 x 10(4) cells/cord) and again dramatically increased during clinical relapse. Low numbers of CD3+ lymphocytes (50-150 cells) were consistently isolated from normal mice. However, the number of T cells infiltrating the spinal cord increased following immunization. The numbers of T cells, macrophages, B cells, neutrophils, and Ig-bearing cells all paralleled the clinical disease course, with T cells and macrophages (showing evidence of myelin breakdown) predominating. T cells infiltrating the spinal cord generally failed to express gamma delta T cell receptors and expressed low levels of IL-2 receptors (5% of infiltrating T cells). These cells were phenotypically dissimilar to peripheral blood leukocytes isolated in parallel, with the spinal cord having a consistently higher ratio (9:1) of CD4+ to CD8+ than the peripheral blood (7:3). The low expression of MEL-14 (L-selectin) and 16a antigen (CD45RBhigh) and the higher levels of Pgp-1 (CD44) expressed by the infiltrating T cells, compared with splenocytes, suggest a preferential recruitment/retention of distinct T cell subsets, possibly memory/primed cells, into the central nervous system from the periphery during neuroimmunological disease.

Inhibition of chronic relapsing experimental allergic encephalomyelitis in the Biozzi AB/H mouse

Chronic relapsing experimental allergic encephalomyelitis (CREAE) can be reproducibly induced in Biozzi AB/H mice following injection of spinal cord homogenate (SCH) emulsified in complete Freund's adjuvant (CFA). Active clinical disease is associated with mononuclear cell infiltration of the central nervous system (CNS), mainly the spinal cord. Whole brain homogenate (BH), however, failed to induce clinical or histological disease. In contrast, substituting sciatic nerve homogenate in the inoculum induced experimental allergic neuritis (EAN). Clinical disease was manifest earlier (13.1 +/- 0.3 days) than CREAE (16.2 +/- 1.4) and was accompanied by mononuclear infiltration of the peripheral nervous system (PNS). In comparison to CREAE induction, pretreating mice with SCH or BH in incomplete Freund's adjuvant (IFA) suppressed the development of SCH-induced disease. The BH was more tolerogenic than the SCH and this hyporesponsiveness was CNS antigen-specific as PNS tissue failed to inhibit the course of CREAE. Tolerance induced by pretreatment with SCH or BH in IFA was reversed by a single injection of 200 mg/kg cyclophosphamide, 2 days prior to CREAE induction. This suggests that IFA-induced hyporesponsiveness is actively regulated, possibly via the action of suppressor cells. In addition, treatment with neuroantigens in IFA appears to be mainly afferent acting as it serves to prevent initial disease induction. This treatment after immunization for CREAE, however, fails to prevent disease progression. Furthermore, treatment with CNS antigens emulsified in IFA during the post-acute remission stage appeared to synchronize and induce (32 +/- 1 days) the onset of clinical relapse, compared with untreated controls (41 +/- 5 days). This indicates that such IFA treatment has minimal value in controlling an ongoing immune disease of the CNS.

Control of immune-mediated disease of the central nervous system requires the use of a neuroactive agent: elucidation by the action of mitoxantrone

Mitoxantrone was used as an immunosuppressive probe to elucidate a means for the control of experimental allergic encephalomyelitis (EAE) induced in Biozzi AB/H mice following injection of spinal cord homogenate emulsified in Freund's adjuvant. A single i.p. injection of 2.5 mg/kg of mitoxantrone, 1-2 days before the anticipated onset of EAE, failed to prevent the majority of animals from developing clinical disease, whereas when the compound was injected directly into the central nervous system (CNS), at this time point, significantly increased therapeutic benefit was evident, with most animals failing to develop clinical EAE. Although the clinical use of intrathecal mitoxantrone is strongly contraindicated, these data suggest that increased therapeutic benefit may be achieved in immune-mediated disease of the CNS by targeting immunosuppressive doses of suitable agents, on lymphocyte activation within the CNS. In addition, direct administration of immunosuppressive doses into the CNS may reduce potentially unwanted (side) effects in the periphery.

Therapy of chronic relapsing experimental allergic encephalomyelitis and the role of the blood-brain barrier: elucidation by the action of Brequinar sodium

The immunosuppressive effect of the novel 4-quinoline carboxylic acid derivative Brequinar sodium on the chronic relapsing experimental allergic encephalomyelitis CREAE model in the Biozzi AB/H mouse was investigated. Although Brequinar sodium actively inhibited peripheral immune responses, it showed a limited potential to control an ongoing disease of the central nervous system (CNS). Doses of 25 mg/kg inhibited in vivo induced proliferative response and prevented EAE when treated from day 9 post-inoculation (p.i.). However, when administered from day 12 p.i. or during the post-acute remission phase-limited effects on the course of disease were observed. By comparison, treatment with a single high dose of cyclophosphamide (200 mg/kg) at these time points was significantly effective in controlling disease. As a possible explanation of the observed results it is suggested that for a compound to be effective in treating an ongoing immune response in the CNS, it must be capable of crossing the blood-brain barrier and act on the disease-inducing cells activated within the CNS. This hypothesis is supported by the finding that intracerebral injections of Brequinar sodium on day 12 p.i. significantly inhibited disease progression. This suggests that strategies aimed at controlling immune-mediated disease of the CNS require therapeutic doses of the compounds to be delivered into the CNS.

An immunoelectron microscopical study of the expression of class II major histocompatibility complex during chronic relapsing experimental allergic encephalomyelitis in Biozzi AB/H mice

Immunoelectron microscopical techniques have been used to study class II major histocompatibility complex (MHC) expression by cells in the spinal cords of Biozzi AB/H mice with chronic relapsing experimental allergic encephalomyelitis. Throughout the course of disease both astrocytes and endothelia failed to express significant levels of class II MHC antigens. The major central nervous system resident cell types found to express class II MHC antigens were the perivascular microglia, with infiltrating macrophages and some lymphocytes being strongly positive.

Mononuclear cell trafficking and plasma protein extravasation into the CNS during chronic relapsing experimental allergic encephalomyelitis in Biozzi AB/H mice

Cellular traffic and plasma protein extravasation across the blood-brain and blood-spinal cord barrier (BBB) have been studied during chronic relapsing experimental allergic encephalomyelitis in Biozzi AB/H mice, using a simultaneous double radioisotope method. There was a general correlation between the clinical course of disease and BBB breakdown, including a resealing of the barrier during remission, although breakdown appeared slightly to precede clinical presentation. The brain was markedly less affected than the spinal cord and was only minimally involved in the relapse phase of disease.

Cytokines in the central nervous system of mice during chronic relapsing experimental allergic encephalomyelitis

Clinical disease phases of chronic relapsing experimental allergic encephalomyelitis (CREAE) in the Biozzi AB/H mouse model are associated with extensive cellular infiltration of the central nervous system, principally the spinal cord. The activation of these cells is further suggested by the immunocytochemical demonstration of cytokines (migration inhibition factor, interferon-gamma, tumour necrosis factor-alpha, and interleukins 1, 2, and 3) within these infiltrates. The in vitro functions attributed to these cytokines indicate their potential role in cell recruitment, activation, and differentiation of the ongoing immune response which could contribute to the pathogenesis of disease.

Expression of vascular addressins and ICAM-1 by endothelial cells in the spinal cord during chronic relapsing experimental allergic encephalomyelitis in the Biozzi AB/H mouse

The expression of adhesion molecules on central nervous system (CNS) endothelia was examined during chronic relapsing experimental allergic encephalomyelitis (CREAE) in the Biozzi AB/H mouse. Active disease episodes (acute and relapse) were associated with the up-regulation of MALA-2, the murine homologue of intercellular adhesion molecule-1 (ICAM-1), on CNS endothelia and the infiltration of ICAM-1-positive mononuclear cells. In addition, the high endothelial venule (HEV)-associated MECA-325 antigen was evident in perivascular lesions, particularly in relapsing disease. The peripheral lymph node HEV-associated vascular addressin defined by MECA-79 antibody was not detectable in the CNS during CREAE. However, the mucosal HEV addressin was evident in lesions, which ultrastructurally was found to be expressed on the surface of endothelial cells by immunoelectron microscopy. The expression of adhesion molecules, such as ICAM-1, may provide a means by which both the initial neuroantigen-specific and the subsequent antigen-non specific cells extravasate into the CNS. Such infiltration may induce the expression of the vascular addressins which may then provide a means of site-selective cellular recruitment leading to disease progression.

Inhibition of chronic relapsing experimental allergic encephalomyelitis in the mouse by the alkyl-lysophospholipid ET-18-OCH3

The effect of the anti-tumour agent alkyl-lysophospholipid (ALP) ET-18-OCH3 on the development of chronic relapsing experimental allergic encephalomyelitis (CREAE) in the mouse was investigated. Experimental allergic encephalomyelitis developed in the majority (greater than 96%) of mice immunized with autologous spinal cord homogenate in Freund's complete adjuvant. Alkyl-lysophospholipid, in doses of 25 mg/kg/day or 50 mg/kg/day, inhibited the onset of clinical signs of acute phase CREAE when orally administered starting on the day of disease induction. Similarly if treatment with 50 mg/kg/day was delayed until day 9 post-inoculation the incidence of disease and severity of clinical signs were also significantly reduced (P less than 0.02) as compared with vehicle fed animals. However, when treatment began on day 12, just prior to the onset of clinical disease, although the incidence of disease was not significantly altered the severity of disease was significantly (P less than 0.002) reduced compared with vehicle treated animals. These data suggest that although the major effect of ALP is on the inhibition of the generation of the autoimmune response there appeared to be some therapeutic benefit at a later stage of acute disease. Therefore, this study was extended to the treatment of post-acute phase remission animals. It was found that the oral administration of 50 mg/kg/day marginally reduced and that 75 mg/kg/day significantly (P less than 0.05) reduced the incidence of relapsing disease compared with vehicle treated controls. This suggests that ET-18-OCH3 may have some potential in the treatment of ongoing autoimmune disease of the central nervous system.

Suppression of demyelination by mitoxantrone

The mode of action of the immunosuppressant mitoxantrone was examined in murine models of demyelinating disease. The drug has been shown to block antigen induced proliferative activity and to inhibit myelin degradation by leucocytes from paralysed mice. Mitoxantrone blocked myelin breakdown by macrophages although phagocytosis was not affected. Further evidence was obtained to indicate that mitoxantrone acts therapeutically in reducing, or at high dose, preventing signs of EAE developing in mice immunized with spinal cord homogenate and Freund's complete adjuvant. Mitoxantrone also significantly inhibited the incidence of relapse when treatment was initiated during the post-acute remission period.

Induction of chronic relapsing experimental allergic encephalomyelitis in Biozzi mice

Experimental allergic encephalomyelitis (EAE) was induced in Biozzi AB/H (antibody high) mice by sensitization with spinal cord homogenate in adjuvant. Biozzi AB/H mice were highly susceptible to EAE induction and followed a chronic relapsing pattern of disease. Disease episodes were characterized by mononuclear infiltration of the central nervous system, with demyelination being particularly evident in relapse. The cellular infiltrates, which were associated with immunoglobulin deposition, consisted of macrophages and primarily CD4-positive T lymphocytes. However, similarly treated Biozzi AB/L (antibody low) mice were markedly less susceptible to EAE induction than AB/H mice. Thus, Biozzi mice should prove valuable for the study of chronic relapsing EAE.

Seizures in the Mongolian gerbil are related to a deficiency in cerebral glutamine synthetase

1. Seizure prone (SP)-gerbils (Meriones unguiculatus) tested repeatedly in an open field exhibited habituation of seizures after one or two trials and subsequently showed more ambulatory activity than non-seizure prone (NSP) individuals. 2. A subset of 5 SP and 5 NSP animals were killed and portions of each cerebral hemisphere, the cerebellum and the brainstem medulla were analysed for glutamine synthetase (GS). 3. GFAP immunohistochemistry was used on forebrain sections to assay astrocyte density. 4. It was found by MANOVA, PCA and regression analyses that seizures and ambulatory activity were related to a deficiency in cerebral GS. 5. Rearing behaviour was related to medullary brainstem and cerebellar GS concentrations. 6. The decreased GS of the seizure-prone gerbils was not apparently associated with a deficiency of astrocytes, perhaps the reverse. 7. The results are discussed in relation to glial-neuronal interactions modulating arousal and the propensity for seizures.