The novel fungal CYP51 inhibitor VT-1598 displays classic dose-dependent antifungal activity in murine models of invasive aspergillosis

Aspergillus spp. infections remain a global concern, with ∼30% attributable mortality of invasive aspergillosis (IA). VT-1598 is a novel fungal CYP51 inhibitor designed for exquisite selectivity versus human CYP enzymes to achieve a maximal therapeutic index and therefore maximal antifungal efficacy. Previously, its broad-spectrum in vitro antifungal activity was reported. We report here the pharmacokinetics (PK) and pharmacodynamics (PD) of VT-1598 in neutropenic mouse models of IA. The plasma area-under-the-curve (AUC) of VT-1598 increased nearly linearly between 5 and 40 mg/kg after 5 days of QD administration (155 and 1033 μg*h/ml, respectively), with a further increase with 40 mg/kg BID dosing (1354 μg*h/ml). When A. fumigatus isolates with in vitro susceptibilities of 0.25 and 1.0 μg/ml were used in a disseminated IA model, VT-1598 treatment produced no decrease in kidney fungal burden at QD 10 mg/kg, intermediate decreases at QD 20 mg/kg and maximum or near maximum decreases at 40 mg/kg QD and BID. The PK/PD relationships of AUCfree/MIC for 1-log killing for the two strains were 5.1 and 1.6 h, respectively, similar to values reported for approved CYP51 inhibitors. In a survival study where animals were observed for 12 days after the last treatment, survival was 100% at the doses tested (20 and 40 mg/kg QD), and fungal burden remained suppressed even though drug wash-out was complete. Similar dose-dependent reductions in lung fungal burden were observed in a pulmonary model of IA. These data strongly support further exploration of VT-1598 for the treatment of this lethal mold infection.

The novel fungal CYP51 inhibitor VT-1598 is efficacious alone and in combination with liposomal amphotericin B in a murine model of cryptococcal meningitis

Objectives

Annual global deaths from cryptococcal meningitis (CM) are estimated at 180 000 and mortality is as high as 30%, even with optimal therapy. VT-1598 is a novel fungal CYP51 inhibitor with potent intrinsic antifungal activity against Cryptococcus. We report here VT-1598's in vivo antifungal activity in a murine model of CM.

Methods

Single-dose plasma and brain pharmacokinetics in mice and MIC for Cryptococcus neoformans H99 were determined prior to efficacy studies. Short-course monotherapy and combination doses were explored with the endpoint of brain fungal burden. A survival study was also conducted using monotherapy treatment with fungal burden measured after a 6 day drug washout.

Results

Oral doses of VT-1598 had good plasma and brain exposure and resulted in significant (P < 0.0001) and dose-dependent reductions in brain fungal burden, reaching a 6 log10 reduction. Unlike either positive drug control (fluconazole or liposomal amphotericin B), both mid and high doses of VT-1598 reduced fungal burden to below levels measured at the start of treatment. When VT-1598 was dosed in the survival study, no VT-1598-treated animal succumbed to the infection. Whereas fluconazole showed a 2.5 log10 increase in fungal burden after the 6 day washout, the VT-1598 mid- and high-dose animals showed almost no regrowth (<0.5 log10). In a separate fungal burden study using suboptimal doses of VT-1598 and liposomal amphotericin B to probe for combination effects, each combination had a positive effect relative to corresponding monotherapies.

Conclusions

These pre-clinical in vivo data strongly support clinical investigation of VT-1598 as a novel therapy for this lethal infection.

Changes in the pattern of plasma extracellular vesicles after severe trauma

Background

Extracellular vesicles (EV) released into the circulation after traumatic injury may influence complications. We thus evaluated the numbers of EV in plasma over 28 days after trauma and evaluated their pro-coagulant and inflammatory effects.

Methods and findings

37 patients suffering trauma with an injury severity score >15 were studied along with 24 healthy controls. Plasma samples were isolated by double centrifugation (2000g 20min; 13000g 2min) from blood collected from within an hour up to 28 days after injury. Plasma EV were counted and sized using nanoparticle tracking analysis (NTA); counts and cellular origins were also determined by flow cytometry (FC) using cell-specific markers. Functional effects were tested in a procoagulant phospholipid assay and in flow-based, leukocyte adhesion assay after endothelial cells (EC) were treated with EV.

We found that EV concentrations measured by NTA were significantly increased in trauma patients compared to healthy controls, and remained elevated over days. In addition, or FC showed that patients with trauma had higher numbers of EV derived from platelets (CD41+), leukocytes (CD45+) and endothelial EC (CD144+). The increases were evident throughout the 28-day follow-up. However, the FC count represented <1% of the count detected by NTA, and only 1–2% of EV identified using NTA had a diameter >400nm. The procoagulant phospholipid activity assay showed that patient plasma accelerated coagulation on day 1 and day 3 after trauma, with coagulation times correlated with EV counts. Furthermore, treatment of EC for 24 hours with plasma containing EV tended to increase the recruitment of peripheral flowing blood mononuclear cells.

Conclusions

EV counted by FC represent a small sub-population of the total load detected by NTA. Both methods however indicate a significant increase in plasma EV after severe traumatic injury that have pro-coagulant and pro-inflammatory effects that may influence outcomes.

Monocyte Subsets Coregulate Inflammatory Responses by Integrated Signaling through TNF and IL-6 at the Endothelial Cell Interface

Two major monocyte subsets, CD14⁺CD16⁻ (classical) and CD14^+/dimCD16⁺ (nonclassical/intermediate), have been described. Each has different functions ascribed in its interactions with vascular endothelial cells (EC), including migration and promoting inflammation. Although monocyte subpopulations have been studied in isolated systems, their influence on EC and on the course of inflammation has been ignored. In this study, using unstimulated or cytokine-activated EC, we observed significant differences in the recruitment, migration, and reverse migration of human monocyte subsets. Associated with this, and based on their patterns of cytokine secretion, there was a difference in their capacity to activate EC and support the secondary recruitment of flowing neutrophils. High levels of TNF were detected in cocultures with nonclassical/intermediate monocytes, the blockade of which significantly reduced neutrophil recruitment. In contrast, classical monocytes secreted high levels of IL-6, the blockade of which resulted in increased neutrophil recruitment. When cocultures contained both monocyte subsets, or when conditioned supernatant from classical monocytes cocultures (IL-6^hi) was added to nonclassical/intermediate monocyte cocultures (TNF^hi), the activating effects of TNF were dramatically reduced, implying that when present, the anti-inflammatory activities of IL-6 were dominant over the proinflammatory activities of TNF. These changes in neutrophil recruitment could be explained by regulation of E-selectin on the cocultured EC. This study suggests that recruited human monocyte subsets trigger a regulatory pathway of cytokine-mediated signaling at the EC interface, and we propose that this is a mechanism for limiting the phlogistic activity of newly recruited monocytes.

Bone Morphogenetic Protein 9 Enhances Lipopolysaccharide-Induced Leukocyte Recruitment to the Vascular Endothelium

Bone morphogenetic protein (BMP)9 is a circulating growth factor that is part of the TGF-β superfamily and is an essential regulator of vascular endothelial homeostasis. Previous studies have suggested a role for BMP9 signaling in leukocyte recruitment to the endothelium, but the directionality of this effect and underlying mechanisms have not been elucidated. In this study, we report that BMP9 upregulates TLR4 expression in human endothelial cells and that BMP9 pretreatment synergistically increases human neutrophil recruitment to LPS-stimulated human endothelial monolayers in an in vitro flow adhesion assay. BMP9 alone did not induce neutrophil recruitment to the endothelium. We also show that E-selectin and VCAM-1, but not ICAM-1, are upregulated in response to BMP9 in LPS-stimulated human endothelial cells. Small interfering RNA knockdown of activin receptor-like kinase 1 inhibited the BMP9-induced expression of TLR4 and VCAM-1 and inhibited BMP9-induced human neutrophil recruitment to LPS-stimulated human endothelial cells. BMP9 treatment also increased leukocyte recruitment within the pulmonary circulation in a mouse acute endotoxemia model. These results demonstrate that although BMP9 alone does not influence leukocyte recruitment, it primes the vascular endothelium to mount a more intense response when challenged with LPS through an increase in TLR4, E-selectin, and VCAM-1 and ultimately through enhanced leukocyte recruitment.

The role of platelets in the recruitment of leukocytes during vascular disease

Besides their role in the formation of thrombus during haemostasis, it is becoming clear that platelets contribute to a number of other processes within the vasculature. Indeed, the integrated function of the thrombotic and inflammatory systems, which results in platelet-mediated recruitment of leukocytes, is now considered to be of great importance in the propagation, progression and pathogenesis of atherosclerotic disease of the arteries. There are three scenarios by which platelets can interact with leukocytes: (1) during haemostasis, when platelets adhere to and are activated on sub-endothelial matrix proteins exposed by vascular damage and then recruit leukocytes to a growing thrombus. (2) Platelets adhere to and are activated on stimulated endothelial cells and then bridge blood borne leukocytes to the vessel wall and. (3) Adhesion between platelets and leukocytes occurs in the blood leading to formation of heterotypic aggregates prior to contact with endothelial cells. In the following review we will not discuss leukocyte recruitment during haemostasis, as this represents a physiological response to tissue trauma that can progress, at least in its early stages, in the absence of inflammation. Rather we will deal with scenarios 2 and 3, as these pathways of platelet–leukocyte interactions are important during inflammation and in chronic inflammatory diseases such as atherosclerosis. Indeed, these interactions mean that leukocytes possess means of adhesion to the vessel wall under conditions that may not normally be permissive of leukocyte–endothelial cell adhesion, meaning that the disease process may be able to bypass the regulatory pathways which would ordinarily moderate the inflammatory response.

Docosahexaenoic acid inhibits the adhesion of flowing neutrophils to cytokine stimulated human umbilical vein endothelial cells

The (n-3) PUFA, DHA, is widely thought to posses the ability to modulate the inflammatory response. However, its modes of interaction with inflammatory cells are poorly understood. In particular, there are limited data on the interactions of DHA with vascular endothelium, the cells that regulate the traffic of leukocytes from the blood into inflamed tissue. Using human umbilical vein endothelial cells (EC) cultured in a flow-based adhesion assay and activated with TNFα, we tested whether supplementing human umbilical vein EC with physiologically achievable concentrations of DHA would inhibit the recruitment of flowing neutrophils. DHA caused a dose-dependent reduction in neutrophil recruitment to the EC surface, although cells that became adherent were activated and could migrate across the human umbilical vein EC monolayer normally. Using EPA as an alternative supplement had no effect on the levels of neutrophil adhesion in this assay. Analysis of adhesion receptor expression by qPCR demonstrated that DHA did not alter the transcriptional activity of human umbilical vein EC. However, DHA did significantly reduce E-selectin expression at the human umbilical vein EC surface without altering the total cellular pool of this adhesion receptor. Thus, we have identified a novel mechanism by which DHA alters the trafficking of leukocytes during inflammation and demonstrate that this involves disruption of intracellular transport mechanisms used to present adhesion molecules on the surface of cytokine-stimulated EC.

Prostaglandin D2 regulates CD4+ memory T cell trafficking across blood vascular endothelium and primes these cells for clearance across lymphatic endothelium

Memory lymphocytes support inflammatory and immune responses. To do this, they enter tissue via blood vascular endothelial cells (BVEC) and leave tissue via lymphatic vascular endothelial cells (LVEC). In this study, we describe a hierarchy of signals, including novel regulatory steps, which direct the sequential migration of human T cells across the blood and the lymphatic EC. Cytokine-stimulated (TNF and IFN) human BVEC preferentially recruited memory T cells from purified PBL. Lymphocyte recruitment from flow could be blocked using a function-neutralizing Ab against CXCR3. However, a receptor antagonist directed against the PGD(2) receptor DP2 (formerly chemoattractant receptor-homologous molecule expressed on Th2 cells) inhibited transendothelial migration, demonstrating that the sequential delivery of the chemokine and prostanoid signals was required for efficient lymphocyte recruitment. CD4(+) T cells recruited by BVEC migrated with significantly greater efficiency across a second barrier of human LVEC, an effect reproduced by the addition of exogenous PGD(2) to nonmigrated cells. Migration across BVEC or exogenous PGD(2) modified the function, but not the expression, of CCR7, so that chemotaxis toward CCL21 was significantly enhanced. Thus, chemokines may not regulate all stages of lymphocyte migration during inflammation, and paradigms describing their trafficking may need to account for the role of PGD(2).

Endovascular aneurysm repair reverses the increased titer and the inflammatory activity of interleukin-1α in the serum of patients with abdominal aortic aneurysm

OBJECTIVE

To examine serum cytokine/chemokine profiles before and 6 months after endovascular repair (EVAR) of abdominal aortic aneurysm (AAA) and to determine whether they correlate with serum inflammatory activity using an in vitro model of leukocyte recruitment.

METHODS

Serum IL-1-α, IL-1β, IL-4, IL-6, IL-8, IL-10, IFN-γ, IP-10, MCP-1, TNF-α, and TNF-β were measured using a cytometry-based immunoassay. To test patient serum for direct inflammatory activity, human endothelial cells (EC) were stimulated with 30% patient serum for 24 hours. To test patient serum for the ability to prime EC for inflammatory responses, EC were incubated with 30% patient serum for 24 hours, followed by stimulation with low-dose (5 U/mL) TNF for 4 hours. Under both regimens of stimulation, the degree of EC activation was assessed by assaying neutrophil recruitment in a flow-based model.

RESULTS

Only IL-1α (67.9 ± 10.4 pg/mL vs 41.9 ± 7.4 pg/mL) and IL-8 (51.5 ± 5.1 vs 32.6 ± 4.7 pg/mL) changed significantly after surgery. Patient serum alone was unable to activate EC. However, serum from both time points could prime EC responses to low-dose TNF. Thus, after priming with preoperative serum, EC stimulated with TNF could recruit 76.7 ± 12.0 neutrophils/mm(2) into the subendothelial cell space. Post-EVAR serum was significantly less effective (44.4 ± 10.2 neutrophils/mm(2)). This reduction in neutrophil recruitment correlated with reduced IL-1α in post-EVAR serum. The addition of a neutralizing antibody against IL-1α to pre-EVAR serum inhibited EC priming and neutrophil recruitment, strongly implying that this cytokine was the priming agent.

CONCLUSION

EVAR reduces serum IL-1α and its inflammatory activity in patient serum. IL-1α is, therefore, implicated in the molecular pathology of AAAs and may have potential as a clinically useful biomarker.

Endothelial cell-borne platelet bridges selectively recruit monocytes in human and mouse models of vascular inflammation

AIMS

Cells of the monocyte lineage are the most abundant inflammatory cells found in atherosclerotic lesions. Dominance of the inflammatory infiltrate by monocytes indicates that there is a disease-driven mechanism supporting their selective recruitment. Previous studies have demonstrated that interactions between endothelial cells (ECs) and platelets may promote monocyte recruitment. In this study, we sought to expand on this knowledge using a complex coculture model of the diseased vessel wall.

METHODS AND RESULTS

Using primary human cells in an in vitro flow-based adhesion assay, we found that secretory arterial smooth muscle cells (SMCs), cocultured with ECs, promote preferential recruitment of monocytes from blood in a TGF-β1-dependent manner. Approximately 85% of leucocytes recruited to the endothelium were CD14(+). Formation of adhesive platelet bridges on ECs was essential for monocyte recruitment as platelet removal or inhibition of adhesion to the ECs abolished monocyte recruitment. Monocytes were recruited from flow by platelet P-selectin and activated by EC-derived CC chemokine ligand 2 (CCL2), although the presentation of CCL2 to adherent monocytes was dependent upon platelet activation and release of CXC chemokine ligand 4 (CXCL4). In an intravital model of TGF-β1-driven vascular inflammation in mice, platelets were also necessary for efficient leucocyte recruitment to vessels of the microcirculation in the cremaster muscle.

CONCLUSIONS

In this study, we have demonstrated that stromal cells found within the diseased artery wall may promote the preferential recruitment of monocytes and this is achieved by establishing a cascade of interactions between SMCs, ECs, platelets, and monocytes.

Omega-3 Fatty acids and inflammation: novel interactions reveal a new step in neutrophil recruitment

While investigating new mechanisms by which the dietary omega-3 fatty acids regulate inflammation, the authors have identified a new step in the regulation of neutrophil migration across vascular endothelial cells.

Inflammation is a physiological response to tissue trauma or infection, but leukocytes, which are the effector cells of the inflammatory process, have powerful tissue remodelling capabilities. Thus, to ensure their precise localisation, passage of leukocytes from the blood into inflamed tissue is tightly regulated. Recruitment of blood borne neutrophils to the tissue stroma occurs during early inflammation. In this process, peptide agonists of the chemokine family are assumed to provide a chemotactic stimulus capable of supporting the migration of neutrophils across vascular endothelial cells, through the basement membrane of the vessel wall, and out into the tissue stroma. Here, we show that, although an initial chemokine stimulus is essential for the recruitment of flowing neutrophils by endothelial cells stimulated with the inflammatory cytokine tumour necrosis factor-α, transit of the endothelial monolayer is regulated by an additional and downstream stimulus. This signal is supplied by the metabolism of the omega-6-polyunsaturated fatty acid (n-6-PUFA), arachidonic acid, into the eicosanoid prostaglandin-D₂ (PGD₂) by cyclooxygenase (COX) enzymes. This new step in the neutrophil recruitment process was revealed when the dietary n-3-PUFA, eicosapentaenoic acid (EPA), was utilised as an alternative substrate for COX enzymes, leading to the generation of PGD₃. This alternative series eicosanoid inhibited the migration of neutrophils across endothelial cells by antagonising the PGD₂ receptor. Here, we describe a new step in the neutrophil recruitment process that relies upon a lipid-mediated signal to regulate the migration of neutrophils across endothelial cells. PGD₂ signalling is subordinate to the chemokine-mediated activation of neutrophils, but without the sequential delivery of this signal, neutrophils fail to penetrate the endothelial cell monolayer. Importantly, the ability of the dietary n-3-PUFA, EPA, to inhibit this process not only revealed an unsuspected level of regulation in the migration of inflammatory leukocytes, it also contributes to our understanding of the interactions of this bioactive lipid with the inflammatory system. Moreover, it indicates the potential for novel therapeutics that target the inflammatory system with greater affinity and/or specificity than supplementing the diet with n-3-PUFAs.

Inflammation is a physiological response to tissue trauma or infection. Neutrophils, which circulate in the blood stream, are the first inflammatory cells to be recruited to a site of tissue inflammation. In response to recruitment signals provided by chemotactic peptides called chemokines, neutrophils traverse the endothelial cell lining of blood vessels. This process involves a multistep cascade of neutrophil adhesion and activation events on the endothelial barrier. While investigating the anti-inflammatory functions of the omega-3 fatty acid , EPA, which is found, for instance, in dietary fish oil, we identified an additional unexpected lipid-derived signal that is essential for neutrophil migration across the endothelium. Our experiments show that a chemokine delivered the first signal needed to bind neutrophils firmly to the endothelial surface. However, in order to traverse the endothelium, a subsequent signal delivered by prostaglandin-D₂ (PGD₂), a lipid derived from the omega-6 fatty acid arachidonic acid, was essential. When EPA, was introduced into the experiment, it was used to form PGD₃. This alternative lipid blocked interactions between PGD₂ and its receptor on neutrophils, preventing the process of migration across the endothelial barrier. Thus, we reveal a new step in the recruitment of neutrophils during inflammation, and a novel anti-inflammatory mechanism of action of dietary EPA.

The interaction between dam methylation sites and Xba1 restriction digest sites in Escherichia coli O157:H7 EDL933

AIMS

The aim of this study was to gain a better understanding of the reason for the predicted pulsed-field gel electrophoresis (PFGE) pattern for the sequenced Escherichia coli O157:H7 EDL933 (EDL933) being different from that observed in practice, using the restriction enzyme Xba1.

METHODS AND RESULTS

Primers were designed that flanked either side of each of the predicted Xba1 restriction sites, and the resultant PCR products were sequenced. No sequencing errors were found in the published genome. The distribution of dam methylation sites within the genome was investigated, and a new PFGE pattern was predicted by assuming that any Xba1 restriction site that coincided with a dam methylation site would not be cut. The estimated mean band sizes were obtained from six replicate gels. It was found that the observed and predicted PFGE patterns were in good agreement.

CONCLUSIONS

The difference between the observed and the predicted PFGE patterns for EDL933, using Xba1, could be accounted for by assuming that the methylated restriction sites were not cut.

SIGNIFICANCE AND IMPACT OF THE STUDY

PFGE is commonly used as a subtyping method. This study provides additional information about the basic technique that could enhance the interpretation of PFGE patterns in comparative studies of the E. coli isolates.

Modelling the epidemiology and transmission of Verocytotoxin-producing Escherichia coli serogroups O26 and O103 in two different calf cohorts

Mathematical models are constructed to investigate the population dynamics of Verocytotoxin-producing Escherichia coli (VTEC) serogroups O26 and O103 in two different calf cohorts. We compare the epidemiological characteristics of these two serogroups within the same calf cohort as well as the same serogroups between the two calf cohorts. The sources of infection are quantified for both calf cohort studies. VTEC serogroups O26 and O103 mainly differ in the rate at which calves acquire infection from sources other than infected calves, while infected calves typically remain infectious for less than 1 week regardless of the serogroups. Fewer than 20% of VTEC-positive samples are the result of calf-to-calf transmission. PFGE typing data are available for VTEC-positive samples to further subdivide the serogroup data in one of the two calf cohort studies. For serogroup O26 but not O103, there is evidence for unequal environmental exposure to infection with different PFGE types.

Enhancement of bacterial competitive fitness by apramycin resistance plasmids from non-pathogenic Escherichia coli

The study of antibiotic resistance has in the past focused on organisms that are pathogenic to humans or animals. However, the development of resistance in commensal organisms is of concern because of possible transfer of resistance genes to zoonotic pathogens. Conjugative plasmids are genetic elements capable of such transfer and are traditionally thought to engender a fitness burden on host bacteria. In this study, conjugative apramycin resistance plasmids isolated from newborn calves were characterized. Calves were raised on a farm that had not used apramycin or related aminoglycoside antibiotics for at least 20 months prior to sampling. Of three apramycin resistance plasmids, one was capable of transfer at very high rates and two were found to confer fitness advantages on new Escherichia coli hosts. This is the first identification of natural plasmids isolated from commensal organisms that are able to confer a fitness advantage on a new host. This work indicates that reservoirs of antibiotic resistance genes in commensal organisms might not decrease if antibiotic usage is halted.

Erythropoietin in thyroid cancer

Erythropoietin (Epo) and the epo-receptor (EpoR) have been implicated in tumor growth, invasion and metastasis. We previously demonstrated Epo and EpoR expression in a small group of archived papillary thyroid cancers (PTC), but were unable to examine functional integrity using formalin-fixed tissues. In the present study, we examined the in vitro expression, induction and function of Epo and EpoR in papillary (NPA), follicular (WRO) and anaplastic (ARO-81) thyroid cancer cells. We found that all three cell lines expressed Epo and EpoR mRNA and that the hypoxia-mimetic cobalt induced Epo expression in all cell lines. None of the growth factors we examined (thyrotropin, vascular endothelial growth factor, IGF-I, or human Epo) altered Epo or EpoR gene expression. Importantly, however, administration of Epo to NPA but not WRO cells resulted in significant alterations in the expression of several mitogenic genes including cyclooxygenase-2 (COX-2), beta-casein (CSN2), wild type p53-induced gene-1 (WIG1) and cathepsin D (CTSD). Epo treated ARO-81 cells only had an increase in CSN2 expression. We conclude that Epo and EpoR are expressed by thyroid cancers and that stimulation of the Epo/EpoR signal pathway results in changes that could impact on the clinical behavior of thyroid cancers.

Molecular characterisation of bovine faecal Escherichia coli shows persistence of defined ampicillin resistant strains and the presence of class 1 integrons on an organic beef farm

Antimicrobial use is heavily restricted on organic farms; however, few studies have been conducted to investigate the impact this has on the epidemiology of resistance in pathogenic and commensal bacteria. We investigated the persistence of antimicrobial resistant Escherichia coli within an organic beef herd over a period of 28 months. Faecal samples collected monthly from three calf cohorts and annually from adult cattle and environmental samples, were screened for the presence of ampicillin, apramycin and nalidixic acid resistant E. coli. The prevalence of ampicillin resistance ranged from 27.3 to 40.7% in the annual herd and environmental samplings (n=22-55) and was greater in the calf cohorts, with a peak cohort prevalence of >47% in all 3 years (n=16-18). Apramycin and nalidixic acid resistant E. coli were rare. Pulsed-field gel electrophoresis (PFGE) identified 10 main genotype groups within the herd, with evidence of strain transmission between different livestock groups, animal species and years. Multiple resistance was found in >44% of isolates tested, with ampicillin, neomycin, sulphamethoxazole and tetracycline carriage the commonest phenotype identified. PCR detected the presence of class 1 integrons in <5% of resistant isolates, 6/7 of which were of cattle origin. These data demonstrate that ampicillin resistant E. coli was common on the farm despite restricted antimicrobial use, although strain diversity was low. Persistence of defined genotype groups was observed between years, together with the transmission of resistant strains between different animal species on the farm.

High frequency transfer and horizontal spread of apramycin resistance in calf faecal Escherichia coli

OBJECTIVES

The aminoglycoside apramycin has been used extensively in animal husbandry in the UK since 1978. This study aimed to determine both whether calves that had never been treated with aminoglycoside antibiotics harboured apramycin-resistant (apr(R)) commensal Escherichia coli, and the mode of spread of the resistance gene.

METHODS

Apr(R) E. coli from weekly calf faecal samples were typed by pulsed-field gel electrophoresis, antibiotic resistance phenotype, plasmid restriction profiles and plasmid transfer frequencies.

RESULTS

During 4 months of weekly sampling, six of 11 calves were found to harbour apr(R) E. coli. All apr(R) E. coli (45) were cross-resistant to gentamicin and tobramycin, which are both used in human medicine. Resistance was conferred by the aac(3)IV gene, present on three different conjugative plasmids. Two of these plasmids also mediated tetracycline and streptomycin resistance. One plasmid demonstrated very high transfer frequencies and was found in three different genotypes.

CONCLUSIONS

We report the presence of apr(R) commensal E. coli in cattle that have never been treated with aminoglycosides. The presence of one conjugative plasmid in three different genotypes is evidence of horizontal spread of this plasmid. This is the first report of a very high transfer frequency of apr(R) plasmid, demonstrating horizontal spread in the commensal flora of food animals.

Alternative approaches to predicting methane emissions from dairy cows1

Previous attempts to apply statistical models, which correlate nutrient intake with methane production, have been of limited value where predictions are obtained for nutrient intakes and diet types outside those used in model construction. Dynamic mechanistic models have proved more suitable for extrapolation, but they remain computationally expensive and are not applied easily in practical situations. The first objective of this research focused on employing conventional techniques to generate statistical models of methane production appropriate to United Kingdom dairy systems. The second objective was to evaluate these models and a model published previously using both United Kingdom and North American data sets. Thirdly, nonlinear models were considered as alternatives to the conventional linear regressions. The United Kingdom calorimetry data used to construct the linear models also were used to develop the three nonlinear alternatives that were all of modified Mitscherlich (monomolecular) form. Of the linear models tested, an equation from the literature proved most reliable across the full range of evaluation data (root mean square prediction error = 21.3%). However, the Mitscherlich models demonstrated the greatest degree of adaptability across diet types and intake level. The most successful model for simulating the independent data was a modified Mitscherlich equation with the steepness parameter set to represent dietary starch-to-ADF ratio (root mean square prediction error = 20.6%). However, when such data were unavailable, simpler Mitscherlich forms relating dry matter or metabolizable energy intake to methane production remained better alternatives relative to their linear counterparts.

Infection of murine keratinocytes with herpes simplex virus type 1 induces the expression of interleukin-10, but not interleukin-1 alpha or tumour necrosis factor-alpha

Herpes simplex virus (HSV) is known to possess several mechanisms whereby it can evade the normal host immune defences. In this study the expression of the immunosuppressive cytokine, interleukin (IL)-10, was monitored following infection of a murine keratinocyte cell line (PAM-212) and compared with the expression of two proinflammatory cytokines: IL-1 alpha and tumour necrosis factor (TNF)-alpha. The PAM-212 cells were infected at a multiplicity of 0.5 with a clinical isolate of HSV type 1, and the mRNA of the three cytokines was assessed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) over the following 24 hr. By 12 hr postinfection the amount of IL-10 mRNA had increased significantly to five-fold greater than that found in uninfected cells (P < 0.01), and this elevated level was maintained until at least 24 hr postinfection. In contrast, IL-1 alpha and TNF-alpha mRNAs were not significantly up-regulated by the HSV infection. Immunostaining with an IL-10 monoclonal antibody (mAb) revealed that cytoplasmic IL-10 protein had increased by 6-12 hr postinfection. This quantity was further increased at 24 hr postinfection, when the viral cytopathic effect was apparent. Viral replication was necessary, but not sufficient on its own, for IL-10 induction. Experiments with HSV mutants lacking functional transactivating factors suggested that the viral transactivating proteins ICP-0 and VP-16 may be necessary for HSV-induced IL-10 expression. Thus, the up-regulation in the expression of IL-10 mRNA and protein induced by HSV early in the infection of keratinocytes represents a specific response and may be part of the viral strategy to avoid local immune defence mechanisms in the skin.

Catecholamines in patients with 22q11.2 deletion syndrome and the low-activity COMT polymorphism

OBJECTIVE

To investigate catecholamine phenotypes and the effects of a tyrosine hydroxylase inhibitor in individuals with the 22q11.2 deletion syndrome and low-activity catechol-O-methyltransferase (COMT).

BACKGROUND

Many persons with the 22q11.2 deletion syndrome suffer severe disability from a characteristic ultrarapid-cycling bipolar disorder and associated "affective storms." One etiologic hypothesis for this condition is that deletion of the COMT gene from one chromosome 22 results in increased catecholamine neurotransmission, particularly if the undeleted chromosome 22 encodes a variant of COMT with low activity.

METHODS

In a preliminary study, plasma, urine, and CSF catecholamines and catecholamine metabolites were measured in four teenage patients with a neuropsychiatric condition associated with 22q11.2 deletion and the low-activity COMT polymorphism on the nondeleted chromosome. In these four patients, and an additional institutionalized adult with the condition, an uncontrolled, open-label trial of metyrosine was administered in an attempt to lower catecholamine production and to alleviate symptoms.

RESULTS

Mild elevations of baseline CSF homovanillic acid (HVA) were found in three of four patients and a moderate reduction in CSF HVA after metyrosine treatment in the patient with the highest pretreatment concentration. The course of the five patients during the clinical trial is described.

CONCLUSIONS

In patients with the 22q11.2 deletion syndrome and low-activity COMT, controlled studies of pharmacologic agents that decrease catecholamine production, block presynaptic catecholamine storage, or enhance S-adenosylmethionine, the cosubstrate of COMT, are warranted.

Glucocorticoid receptor gene expression is unaltered in hippocampal neurons in Alzheimer's disease

Excessive glucocorticoid levels increase the metabolic vulnerability of hippocampal neurons to a wide variety of insults. Since glucocorticoid hypersecretion occurs in Alzheimer's-type dementia it has been proposed that a primary reduction in hippocampal glucocorticoid receptor expression leads to failure of feedback, hypercortisolemia and hence further neuronal loss. However, we have recently found that lesions of the cholinergic innervation of the hippocampus--known to be severely affected in Alzheimer's disease--increase corticosteroid receptor gene expression in the rat hippocampus. We have now examined both glucocorticoid (GR) and mineralocorticoid (MR) receptor gene expression in individual neurons in human postmortem hippocampus, using in situ hybridization histochemistry in 5 patients with Alzheimer's disease (81 +/- 3 years) and 7 controls (81 +/- 7 years) without neurological disease. The distribution and intensity of MR and GR mRNA expression in the hippocampus of Alzheimer's disease were similar to that in control tissue, with high expression in dentate gyrus and CA2-4, but significantly lower expression in CA1. In a separate group of patients with Alzheimer's disease we found significantly increased 24 h integrated plasma cortisol levels (59% greater than age-matched controls) and reduced cortisol-binding globulin (21% lower). These data do not suggest a primary deficiency of biosynthesis of hippocampal corticosteroid receptors in Alzheimer's disease. The maintenance of hippocampal GR and MR gene expression, in the face of an increased glucocorticoid feedback signal, may reflect loss of the cholinergic innervation.

Herpes simplex virus type 1 DNA is present in specific regions of brain from aged people with and without senile dementia of the Alzheimer type

We have investigated the possible involvement of viruses, specifically Herpes simplex virus type 1, in senile dementia of the Alzheimer type (SDAT). Using the highly sensitive polymerase chain reaction, we have detected the viral thymidine kinase gene in post-mortem brain from 14/21 cases of senile dementia of the Alzheimer type and 9/15 elderly normals. The temporal cortex and hippocampus were usually virus-positive; in contrast, the occipital cortex was virus-negative in 9/9 SDAT cases and 5/5 elderly normals. Temporal and frontal cortex from younger normals (five infants and five middle-aged) were negative. Thus, the presence of Herpes simplex virus type 1 DNA is a region-dependent feature of the aged brain.

Mutation in codon 713 of the beta amyloid precursor protein gene presenting with schizophrenia

Following reports of mutations of codon 717 in exon 17 of the amyloid precursor protein (APP) gene in early-onset familial Alzheimer's disease, we screened exon 17 for new mutations in presenile dementia. The majority of the 105 patients screened had definite or probable Alzheimer's disease, but we also included atypical cases and some chronic schizophrenics. We identified a single abnormal case--a chronic schizophrenic with cognitive defects. Sequencing revealed a C to T nucleotide substitution which produces an alanine to valine change at codon 713. We were unable to detect the mutation in the remaining members of the original cohort nor in a further 100 chronic schizophrenics and 100 non-demented controls. Nonetheless, the position of the mutation in a critical portion of the APP gene suggests that it may well prove to be pathogenic.

Enzyme activities in relation to pH and lactate in postmortem brain in Alzheimer-type and other dementias

Phosphate-activated glutaminase, glutamic acid decarboxylase, pyruvate dehydrogenase, succinic dehydrogenase, pH, and lactate were measured in frontal cortex and caudate nucleus of postmortem brains from cases of Alzheimer-type dementia (ATD), Down's syndrome, Huntington's disease, and one case of Pick's disease, as well as from sudden death and agonal controls. Lactate levels were higher and pH, phosphate-activated glutaminase, and glutamic acid decarboxylase levels were lower in the agonal controls than in the sudden death controls. Phosphate-activated glutaminase and glutamic acid decarboxylase were correlated with tissue pH and lactate, and also were reduced by in vitro acidification, suggesting that the low activities of these enzymes in agonal controls were related to decreased pH consequent upon lactate accumulation. Compared with control tissues at the same pH, phosphate-activated glutaminase and glutamic acid decarboxylase were unaltered in ATD and Down's frontal cortex and reduced in Huntington's caudate nucleus, and glutamic acid decarboxylase was reduced in Huntington's frontal cortex. These data suggest that GABAergic neurons are not affected in ATD and confirm the GABAergic defect in Huntington's disease. Pyruvate dehydrogenase and succinic dehydrogenase activities were the same in agonal controls and sudden death controls and were unaffected by acid pH and lactate in vitro, and pyruvate dehydrogenase was not correlated with pH or lactate. Reduced pyruvate dehydrogenase in frontal cortex of individual ATD, Down's, and Pick's cases, and in the caudate nucleus of Huntington's and Down's cases, was accompanied by gliosis/neuron loss. We conclude that decreased pyruvate dehydrogenase reflects neuronal loss.

Calcitonin gene-related peptide and calcitonin immunoreactivity in brain and spinal cord in Alzheimer-type dementia

Calcitonin gene-related peptide (CGRP) and calcitonin (CT) immunoreactivity were measured in hypothalamus, parahippocampal gyrus, pituitary and grey matter of the posterior and anterior spinal cord from five to six cases of Alzheimer-type dementia (ATD) and from five to six controls. CGRP was slightly increased and choline acetyltransferase decreased in the anterior grey of ATD spinal cord. No other significant differences were observed between the levels of the two peptides in the ATD and control tissues, even in the parahippocampal gyrus and posterior grey of the spinal cord which had reduced choline acetyltransferase activity in the ATD cases. These results show that CGRP and CT are not affected in ATD, either as a consequence of a direct effect on peptidergic neurons or secondary to the loss of choline acetyltransferase activity.

Cholinergic enzymes in the spinal cord in Alzheimer-type dementia

Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) were measured in anterior and posterior grey matter of the lumbar spinal cord and in temporal and frontal cortex from six cases of Alzheimer-type dementia (ATD), one case of Down's syndrome, three cases of schizophrenia (SZ) and six controls. Compared with control and SZ values, ChAT and AChE were reduced in ATD cerebral cortex. ChAT was reduced, and AChE unaltered, in ATD spinal cord. Decreased cord ChAT may be related to electrophysiological abnormalities which have been reported in motor nerves of patients with Alzheimer's disease.

An antiserum to the extracellular domain of the Alzheimer amyloid precursor recognizes 70 and 88 kDa brain proteins

An antiserum raised to the extracellular domain (residues 556-566) of the Alzheimer amyloid precursor protein recognized 70 and 88 kDa proteins in Western blots of rat, Alzheimer, Down's syndrome and control human brain separated by SDS-PAGE. The 70 kDa protein band was resolved into 5 spots by two-dimensional electrophoresis. The findings provide further evidence that a 70 kDa protein is a metabolite of the amyloid precursor protein and reveal an 88 kDa protein which was reduced in 3 out of 6 brains with Alzheimer pathology.

An antiserum to the C-terminus of the Alzheimer amyloid precursor recognizes a soluble 70 kDa protein

A rabbit antiserum to the C-terminus of the putative brain amyloid precursor was used to probe Western blots of tissue proteins separated by SDS-PAGE. The antiserum specifically labelled a protein of approx. 70 kDa in the Tris buffer-soluble fraction of brain samples from rat, Alzheimer subjects, cases of young and old Down's syndrome, and age-matched controls. The 70 kDa protein was present in low concentrations in human liver and kidney, and was undetectable in human skeletal muscle. The 70 kDa protein may be a metabolite of the amyloid precursor.

Congo red birefringent structures in the hypothalamus in senile dementia of the Alzheimer type

Serial cryostat sections of hypothalamus from four cases of Alzheimer-type dementia and four controls were stained with Congo red and examined for birefringence. Green birefringence and dichroism was associated with (a) neurofibrillary tangles, which were most numerous at the level of the tuberomammillary nucleus where they were found in large acetylcholinesterase-positive neurons; (b) neuropil processes within tangle fields; (c) a few plaque cores in the mammillary body; (d) spicules at the ependyma of the third ventricle, and (e) blood vessels. Birefringence (e) had different properties from (a) to (d) and was considered to be due to collagen. The ependymal spicules did not react with an antibody which recognized the tangles and neuropil processes. Each Alzheimer case had many more tangles than the control cases. Birefringence in (b)-(d) tended to be greater in the Alzheimer than in the control cases. This study confirms previous reports of large numbers of tangles in circumscribed areas of caudal hypothalamus in Alzheimer-type dementia and demonstrates that Congo red staining reveals abnormalities in hypothalamic structures (neuropil processes and ependyma) not demonstrated by other staining techniques.

Solubility of neurofibrillary tangles and ultrastructure of paired helical filaments in sodium dodecylsulphate

Temporal cortex from 14 cases of Alzheimer-type dementia and 6 cases of Down's syndrome, all selected for severe Alzheimer pathology, was homogenised in distilled water, NaOH, or sodium dodecylsulphate (SDS) containing 0.1% beta-mercaptoethanol. The homogenates were stained with Congo red, and the neurofibrillary tangles and plaque cores were counted under crossed-polarisation microscopy. The number of tangles and plaque cores in the water-treated extracts was not related to age, sex, post-mortem interval or duration of dementia. The number of tangles after extraction in SDS or NaOH, as a percentage of tangles in water-treated extracts, was 57 +/- 25 (mean +/- SD) for 1% SDS, 43 +/- 17 for 5% SDS and 37 +/- 22 for 0.2 M NaOH. Plaque cores were essentially insoluble in all three agents. The percentage of tangles insoluble in 1% SDS did not correlate with age or post-mortem interval but decreased with increasing duration of dementia. Enhanced tangle solubility with increasing duration of dementia suggests that the nature of tangles changes with time; one possibility is that this reflects transformation of intracellular to extracellular tangles. Paired helical filament (PHF) length and the number of repeats per PHF were measured in electron micrographs of PHF prepared with and without treatment by 1% SDS. There was no significant multimodality of PHF length to suggest that PHF broke at regular intervals. The mean repeat length (PHF length/number of repeats) was greater for PHF isolated in the presence of 1% SDS than in its absence, showing that SDS affects ultrastructure by untwisting PHF.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies to normal and Alzheimer human brain structures from non-immunised mice of various ages

Supernatants from mouse spleen hybridoma lines established without previous immunisation were screened immunohistochemically against cryostat sections of human temporal cortex and found to stain a variety of brain structures, including Alzheimer plaques and tangles. The age of the mice had no effect on antibody production.

Autoantibodies to Alzheimer and normal brain structures from virus-transformed lymphocytes

B-Lymphocytes from two patients with Alzheimer's disease and one healthy subject were transformed into lymphoblastoid cells by exposure to Epstein-Barr virus. In culture, more than 50% of these cells secreted sufficient IgM or IgG antibody (mainly IgM) to allow immunohistochemical screening against cryostat sections of normal and Alzheimer temporal cortex. More than 30% of the IgM antibodies from each subject recognised brain components, namely: neurons, astrocytes, nuclei, nucleoli, and Alzheimer plaques and neurofibrillary tangles. This methodology represents a major addition to the procedures currently available for the generation of antibodies towards normal and pathological structures in human brain.

Monoclonal antibodies to human hypoglossal nucleus which stain neurons and astrocytes in normal brains and brains from cases of Alzheimer-type dementia

Monoclonal antibodies were raised to membranes of hypoglossal nuclei from normal human post-mortem brain. Two of these clones were recloned to yield antibodies ES.18 and ES.19. Antibody ES.18 stained some, but not all, neuronal perikarya in the medulla oblongata and other brain areas. Neurons stained by this antibody did not have a common neurotransmitter or physiological function, although they tended to be large. Perikarya in the basal forebrain nucleus from a case of Alzheimer-type dementia were stained much more intensely by ES.18 than were these perikarya in a control brain. Antibody ES.19 did not stain neuronal perikarya but stained glial fibrillary acidic protein-positive processes below the pia, in the subependymal layer and in the molecular layer of the cerebellum of control and Alzheimer brains. This antibody also stained the numerous glial fibrillary acidic protein-positive astrocytes in Alzheimer cerebral cortex, but did not stain glial fibrillary acidic protein-positive astrocytes in the white matter of brains from controls or cases of Alzheimer-type dementia. The staining pattern of ES.19 suggests that fibrous astrocytes in Alzheimer cerebral cortex are antigenically different from fibrous astrocytes in white matter.

Regional brain 5-hydroxytryptamine levels are reduced in senile Down's syndrome as in Alzheimer's disease

5-Hydroxytryptamine (5-HT) and choline acetyltransferase (ChAT) were assayed in amygdala, cingulate cortex and caudate nucleus of post-mortem brains from 7 cases of Down's syndrome (6 with the neuropathological features of Alzheimer's disease and one with no such features), 9 cases of Alzheimer's disease and 12 controls. 5-HT was markedly reduced in all 3 areas of the pathologically affected Down brains, unaltered in the Down brain with no Alzheimer pathology and reduced in the amygdala and cingulate cortex of the Alzheimer brains. ChAT showed a similar pattern of reduction. These results supply biochemical evidence that 5-hydroxytryptaminergic, as well as cholinergic, neurons are reduced in Down's syndrome with Alzheimer pathology.

Fluorescence activated cell sorting (FACS) as a separation method for neurofibrillary tangles in Alzheimer's disease

We have developed a fluorescence cell sorting (FACS) method for the separation of neurofibrillary tangles from post-mortem brain from cases of Alzheimer's disease and Down's syndrome. Neurofibrillary tangles in brain homogenate were selectively labelled with the fluorescent dye congo red. Using FACS the tangles were separated from other tissue components on the basis of fluorescence and forward-angle light scatter to give a fraction highly enriched in tangles, which were identified by light and crossed polarisation microscopy. Tangles were not observed in a comparison fraction, collected at the same time, of weakly fluorescent particles of similar size to the tangles. Thus FACS provides a non-denaturing method for obtaining preparations of neurofibrillary tangles for purposes of further analysis.

High-molecular-weight forms of somatostatin are reduced in Alzheimer's disease and Down's syndrome

Four molecular forms of somatostatin-like immunoreactivity (SOM-LI) are present in the human temporal cortex: SOM-14, SOM-28 and high-molecular-weight forms (HMW-SOM) of 7500 and 12,000 daltons. SOM-14 and HMW-SOM are depleted in cortical tissue from cases of pre-senile Alzheimer-type dementia (ATD), but there is a disproportionate reduction in HMW-SOM. In cases of Down's syndrome (DS) with the neuropathological and neurochemical changes of ATD, the total concentration of SOM-LI was similar to that in control cases and the proportions of molecular forms present were comparable. However, there was a significant reduction in the concentration of HMW-SOM. These results show that ATD and DS may share a common abnormality in the biosynthesis and/or post-translational processing of cortical SOM.

Increased proteins in post-mortem brain in a case of Pick's disease and in Huntington's disease

Soluble proteins from temporal cortex and caudate nucleus from a case of Pick's disease, 5 cases of Huntington's disease and 5 controls were analysed by SDS-polyacrylamide gel electrophoresis. Acidic proteins of molecular weight 39 000-42 000, which showed glial fibrillary acidic protein immunoreactivity, were increased in temporal cortex of the Pick's case. Proteins of these molecular weights were also increased in caudate nucleus of the Huntington's cases. Our results show that the astrocytic gliosis observed in temporal cortex in Pick's disease and in caudate nucleus in Huntington's disease is associated with qualitatively similar increased amounts of soluble glial fibrillary acidic protein.

Reductions in soluble brain proteins in older subjects with Down's syndrome

Soluble proteins from temporal cortex and caudate nucleus from 6 cases of Down's syndrome (5 aged over 50 and 1 aged 27 years) and 7 controls were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. In older Down's syndrome cases, reductions in tubulin and 5 other proteins were observed in cortex which had the neuropathology of Alzheimer's disease but not in caudate nucleus. No protein changes or neuropathological features of Alzheimer's disease were found in the youngest Down's syndrome case. The protein changes appear to be associated with the neuropathological features of Alzheimer's disease and not with Down's syndrome itself.

Reduced proteins in temporal cortex in Alzheimer's disease: an electrophoretic study

Cytoplasmic and pellet fractions from post-mortem temporal cortex from eight cases of neuropathologically confirmed Alzheimer's disease, one case of cerebrovascular dementia, and five controls were examined by sodium dodecylsulphate-polyacrylamide gel electrophoresis. No differences were observed in the cytoplasmic proteins from the five controls and the case of cerebrovascular dementia. In five cases of Alzheimer's disease with neurone loss, there was a major loss of a cytoplasmic 55,000-dalton protein identified as tubulin and variable reductions in cytoplasmic proteins of molecular weights of 28,000, 30,000, 92,000, and 200,000 daltons. Three cases of Alzheimer's disease had no detectable neurone loss; two of these cases had protein patterns indistinguishable from the controls and one showed some reduction in soluble tubulin only. These results indicate that decreases of particular proteins in the temporal cortex in Alzheimer's disease may be associated with neurone loss.

Neurotensin immunoreactivity in post-mortem brain is increased in Down's syndrome but not in Alzheimer-type dementia

Neurotensin immunoreactivity and choline acetyltransferase (ChAT) activity were measured in post-mortem brain from 10 cases of Down's syndrome (7 aged 53-63 years, one aged 27 years, one aged 16 months and one aged 10 months), 6 cases of Alzheimer-type dementia (ATD) and 19 control subjects (13 aged 40-88 years and 6 aged 9-18 months). Neurotensin concentrations in anterior and basal hypothalamus, amygdala, septal area, caudate nucleus and temporal cortex were unaltered in ATD. The concentrations of neurotensin were significantly increased in the caudate nucleus, temporal cortex and frontal cortex in the cases of Down's syndrome aged 53-63 years with the neuropathological features of ATD, and were also increased in the cerebral cortex of the 27-year-old, which did not have the neuropathological features of ATD, and in two infant Down's cases. ChAT activity was reduced in the ATD and the 53-63-year-old cases of Down's syndrome, but not in the 27-year or 10-month-old Down's cases. The increased neurotensin concentrations appear to be a feature of Down's syndrome not related to the presence of plaques and neurofibrillary tangles or to a deficit in ChAT activity.

Biochemical studies on rabbits with aluminium induced neurofilament accumulations

The activities of acid phosphatase, hexosaminidase, beta-galactosidase, Mg2+-stimulated Na+K+ATPase, fumarase and ATP:citrate lyase were measured in grey matter of rabbit spinal cord 7-8 days after intra-ventricular or intra-cisternal injection of aluminium. RNA, DNA, and water content were measured in whole spinal cords. Choline acetyltransferase (CAT) and acetylcholinesterase were assayed in dorsal grey matter of the cord, which contained no aluminium-induced neurofilament accumulations (NFAs), and ventral grey matter, which had large numbers of such NFAs. CAT was also assayed in the hypoglossal nerve. None of these measures were consistently altered in the aluminium treated rabbits, although the activity of beta-galactosidase was increased in the NFA-free caudate nucleus of rabbits given aluminium intra-ventricularly, possibly due to the presence of phagocytes on the ventricular surface of the caudate. It is concluded that neither aluminium nor its induced NFAs has a gross effect on neuronal metabolism within 7-8 days.

Distribution of phosphate-activated glutaminase, succinic dehydrogenase, pyruvate dehydrogenase and gamma-glutamyl transpeptidase in post-mortem brain from Huntington's disease and agonal cases

The activity of phosphate-activated glutaminase was reduced throughout the brain of cases with longstanding illnesses (agonal controls) compared to cases dying suddenly. The reduction was less marked in cortical than sub-cortical areas, with the caudate nucleus occupying an intermediate position. In control brains succinic dehydrogenase and pyruvate dehydrogenase were little affected by the ante-mortem clinical state. Of 9 brain areas studied, only the caudate nucleus showed a reduction of phosphate-activated glutaminase and succinic dehydrogenase in Huntington's disease greater than in agonal controls. The levels of succinic dehydrogenase and pyruvate dehydrogenase were highly correlated in frontal cortex and in caudate nucleus of Huntington's disease and control brains. There was a significant reduction in pyruvate dehydrogenase mean activity and a significant increase in gamma-glutamyl transpeptidase mean activity in Huntington's disease caudate nucleus. The level of pyruvate dehydrogenase significantly decreased and the level of gamma-glutamyl transpeptidase significantly increased with increasing duration of illness, possibly due to a progressive loss of neurons and increase in the density of glia in Huntington's disease caudate nucleus.