Apmis

CHEN, M.; BENNEDSEN, M.; ZHAI, L.; KHARAZMI, A.

doi: 10.1034/j.1600-0463.2001.091201.xpmid: 11846720

A 65 kD membrane‐associated NADH‐fumarate reductase subunit, which has a molecular weight similar to that of one of the enzyme subunits from bacteria, was purified from Leishmania donovani promastigotes. NADH‐fumarate reductase and other mitochondrial enzymatic activities of L. major and L. donovani promastigotes and amastigotes were investigated. The presence of NADH‐fumarate reductase was demonstrated in digitonin‐permeabilized L. major promastigotes and mitochondria of L. major and L. donovani promastigotes and amastigotes. The activity of solubilized NADH‐fumarate reductase was measured in L. major and L. donovani promastigotes. Succinate exhibited a clear concentration‐dependent inhibitory effect on fumarate reductase, whereas fumarate also exhibited a clear concentration‐dependent inhibitory effect on succinate dehydrogenase. The data indicate that fumarate reductase is an obligatory component of the respiratory chain of the parasite. Since the enzyme is an important component in the intermediate metabolism in the Leishmania parasite and is absent in mammalian cells, it could be a potential target for antileishmanial drugs.

BRAULIO, VALERIA BENDER; DE QUEIROZ CÔRTES, MAURO; BORGES‐NETO, ARMANDO A.; BASTOS, MARCO AURÉLIO; CRUZ, MARCELO SOUZA; FRACALANZA, SÉRGIO EDUARDO

doi: 10.1034/j.1600-0463.2001.091202.xpmid: 11846721

Chronic ethanol ingestion has been associated with small intestine morphological changes, disrupted host mucosal defenses and bacterial overgrowth. Since bacterial translocation (BT) may result from such alterations, we have investigated the potential effect of chronic ethanol consumption on BT. For this purpose, male Wistar rats were fed a liquid diet containing 5% v/v ethanol for 4 weeks (EG, n=16), and a pair‐fed group received equal daily amounts of calories in a similar diet without ethanol (PFG, n=16). On experimental day 29, distal ileum ligature and small intestine inoculation of a tetracycline‐resistant E. coli strain (Tc®E. coli R6) followed by duodenal ligature was performed. After 1 or 5 h post inoculation, mesenteric lymph nodes, liver, spleen and kidney were excised. Unexpectedly, rats of the EG presented markedly less BT to the mesenteric lymph nodes (p<0.001) and to the other organs examined compared to rats of the PFG. This BT inhibition was observed at 1 and 5 h after bacterial inoculation, and may be attributed exclusively to chronic ethanol ingestion. Since alcoholism is well known to decrease host immunity, these results suggest that other factors, independent of the immune function, may be involved in the BT inhibition observed in this study.

ABEBE, F.; GAARDER, P. I.; PETROS, B.; GUNDERSEN, S. G.

doi: 10.1034/j.1600-0463.2001.091203.xpmid: 11846722

Acquired immunity is believed to be the main factor in the age‐related differences in prevalence and intensity of Schistosoma infections. We studied antibody responses against S. mansoni soluble egg antigen (SEA) by ELISA in children before treatment, 5 weeks and one year after treatment. After screening for S. mansoni infection, positive children were treated with praziquantel (40 mg per kg body weight). Infection rate was significantly higher in boys younger than 12 years than in girls in the same age group. Levels of all antibody isotypes, except IgG1 (before treatment) or IgA (one year after treatment), were higher in children older or equal to 12 years than in those younger. The difference between age groups was significant for IgE, IgM, IgG3 and IgG4 (before treatment) and IgE (one year after treatment). Similarly, all antibody isotypes, except IgE, before treatment were higher in boys than in girls. At 5 weeks after treatment, IgG, IgE and IgG1 showed an increasing tendency, whereas IgM and IgG3 tended to decrease. One year after treatment, significant decreases were observed in IgG, IgG1 and IgG4 and a significant increase in IgG2 levels. The study presents further evidence for the difference in acquired immunity between younger and older children, and between boys and girls. The study also suggests that praziquantel differentially affects antibody responses against S. mansoni SEA.

EGGERTSEN, GÖSTA; NYBERG, GUDRUN; NILSSON, BO; NILSSON, ULF; SVALANDER, CHRISTIAN T.

doi: 10.1034/j.1600-0463.2001.091204.xpmid: 11846723

Among patients with early severe impairment of renal allograft function we have previously identified a group displaying isolated deposition of complement factor C3 in glomeruli. Here we studied the pattern of complement deposition more extensively in allograft biopsies from five patients using an immunofluorescence technique. We found a prominent deposition of C3c, C3d and C4d antigens in the glomerular capillary walls, and a positive reaction to vitronectin (S‐protein), but only trace amounts of the complement factor C9 neoepitope. Clq, C4c, C3a, iC3b, factor B, properdin, immunoglobulins IgG, IgA or IgM were not found in glomeruli or in any other cortical structure. These findings indicate that most of the demonstrated glomerular C3 consists of C3b and/or C3c/C3d molecules. By immunoelectron microscopy the C3 antigen was found within the glomerular basement membrane. Our findings indicate that there is a mechanism of complement activation involving the early steps of the classical pathway, despite the lack of demonstrable immunoglobulins in the tissue. In analogy with similar reactions described recently in heart allografts, we suggest that this may be a manifestation of a humoral rejection, possibly mediated by a low titer of circulating antibodies directed against endothelial surface antigens, presumed to be the initial step leading to complement activation.

TULINIUS, H.; ÖGMUNDSDOTTIR, H. M.; KRISTINSSON, K. G.; SIGVALDASON, H.; SIGVALDADOTTIR, E.; KRISTJANSDOTTIR, G.; SIGFUSSON, N.

doi: 10.1034/j.1600-0463.2001.091205.xpmid: 11846724

H. pylori infection is considered a causal agent of duodenal ulcer and a significant risk factor for gastric cancer. Retrospective cohort studies have demonstrated a significant association between presence of antibody to H. pylori and gastric cancer when using samples obtained years before the diagnosis but not at the time of diagnosis. The present study investigates, in a population‐based cohort, whether a decline occurs in H. pylori antibody levels before the diagnosis of stomach cancer. Repeat samples (2 to 5) were available from 23 persons with gastric cancer taken up to 20 years before the diagnosis and 128 control subjects matched for gender, age, time and number of repeat samples. The odds ratio of developing stomach cancer was 1.16 (95% CI 1.05–1.28) for those showing decline in antibody levels of 1 relative antibody activity unit per year versus those with constant or rising levels. We conclude that this decline in antibody levels in cases, and not in controls, supports an active role of H. pylori in the pathogenesis of gastric cancer by causing atrophic gastritis, and provides a better risk assessment for gastric cancer compared to single measurements.

MOYO, SYLVESTER R.; MAELAND, JOHAN A.; LYNG, RANDI V.

doi: 10.1034/j.1600-0463.2001.091206.xpmid: 11846725

The streptococcal R1 protein was studied by means of anti‐R1 antibodies prepared by appropriate cross‐absorption of rabbit antiserum raised against the group B streptococcal (GBS) strain ATCC 12403 (D136C), serotype III/R1. The protein was a ladder‐forming antigen according to banding patterns in immunoblotting, similar to several other GBS proteins, and was susceptible to digestion by both pepsin and trypsin. Antibody‐based testing revealed that 10% of Norwegian GBS isolates expressed the R1 protein, most frequently capsular antigen type V strains (72%) and less frequently type III strains (3%). None of 132 GBS strains from Zimbabwe, including 39 type V strains, expressed the R1 protein. R1‐specific rabbit antibodies showed protective activity in mice challenged with a GBS type V/R1 strain. The results show that the R1 protein is an important GBS serotype marker in strains from certain geographical areas, notably for the subtyping of capsular type V strains, and that this protein is a target of protective antibodies.

HANSEN, ALASTAIR B.; BOUCHELOUCHE, KIRSTEN; OLESEN, JETTE D.

doi: 10.1034/j.1600-0463.2001.091207.xpmid: 11846726

To date, immunosuppressive therapy for allograft rejection is based on a generalized inhibition of the recipient's T cells, rendering the individual less resistant to infections and malignancies. In order to change this therapeutic approach towards the induction of specific transplant tolerance, it is essential to identify the cells and molecular pathways involved in direct allorecognition. An in vitro model with interferon‐gamma (IFN‐gamma)‐stimulated human lung microvascular endothelial cells (HMVEC‐L) as targets and allogenic T cells as responders was used to identify donor cells for recipient cellular immunorecognition. HMVEC‐L activated purified allogenic T cells in cocultures. This activation was partly mediated by lymphocyte function antigen‐3 (LFA‐3), but not CD86, as shown by monoclonal antibody (mAb) inhibition. This finding was supported by the expression of LFA‐3 antigen, but not CD86, on IFN‐gamma‐stimulated HMVEC‐L. Surprisingly, even in the absence of T‐cell proliferation, T cells were capable of enhancing LFA‐3 antigen, but not CD86 expression on HMVEC‐L. In conclusion, HMVEC‐L are capable of direct allostimulation of human T cells, partly through an LFA‐3‐dependent costimulatory pathway. Since ICAM‐1 expression on HMVEC is greatly enhanced by IFN‐gamma and T cell coculturing, this molecule may serve as an additional costimulator. A reciprocal HMVEC‐L stimulation by allogenic T‐cells occurs, even without T‐cell proliferation, possibly representing a preproliferative phase. Since this study included a single target as well as responder cell donor, further studies with multiple donors are needed to evaluate possible variations.

RUÍZ, M.; RODRÍGUEZ, J. C.; ESCRIBANO, I.; GARCÍA‐MARTÍNEZ, J.; RODRÍGUEZ‐VALERA, F.; ROYO, G.

doi: 10.1034/j.1600-0463.2001.091208.xpmid: 11846727

A total of 19,723 clinical samples were cultivated for the detection of mycobacteria from January 1995 to March 2001. The 203 strains of nontuberculous mycobacteria isolated were identified with the use of molecular techniques in combination with traditional biochemical tests. The molecular methods applied were PCR‐restriction fragment length polymorphism analysis (PRA) alone or in combination with 16S rRNA and 16S‐23S spacer sequencing. The patient records of those with specimens positive for mycobacteria were analysed to evaluate the clinical significance of the culture results. Twenty‐five of the 124 patients analysed (20%) were regarded as having clinical mycobacteriosis. The main species associated with mycobacteriosis were: Mycobacterium avium (13 cases), M. intracellulare (2 cases), M. kansasii (5 cases), M. chelonae (2 cases), M. malmoense (1 case), M. scrofulaceum (1 case) and M. marinum (1 case). The use of PRA alone or in combination with gene sequencing provided valuable help in discerning mycobacteria at both the intra‐ and interspecies level, thus contributing to a faster and more efficient diagnosis and epidemiological follow‐up.

TORP, SVERRE HELGE; GRANLI, UNN SOPHIE

doi: 10.1034/j.1600-0463.2001.091209.xpmid: 11846728

Determination of proliferative activity in tumours may be valuable in diagnosis and prognosis. In this study, commonly used proliferation markers were investigated and compared in 12 cases of human glioblastoma. Paraffin sections were incubated with four commercial Ki67‐equivalent antibodies, anti‐PCNA, and anti‐bcl‐2. S‐phase fraction and mitotic activity were determined as well. The different Ki67 antibodies gave satisfactory immunostainings, though they provided a wide range of proliferation indices (PI) intra‐ and intertumorally. Correlations between the Ki67 antibodies and the other proliferation markers were, broadly speaking, poor. PCNA immunostaining was hampered by disturbing background staining. Few bcl‐2‐immunoreactive cells were observed, mainly gemistocytes. Flow cytometric analyses provided reliable S‐phase fraction values, and two aneuploid tumours were detected. The mitotic activity was generally high. Thus, mitotic counting remains a convenient method for assessing proliferative activity in astrocytic tumours. Ki67 antibodies are important alternatives, for instance in stereotactic brain biopsies. Under all circumstances, proliferation markers should be used in combination with established histopathological criteria for malignancy in these tumours.

GÜLKESEN, KEMAL HAKAN; KILIÇARSLAN, BAHAR; ALTUNBAŞ, HASAN ALI; KARPUZOGˇLU, GÜLTEN

doi: 10.1034/j.1600-0463.2001.091210.xpmid: 11846729

EGFR (epidermal growth factor receptor), p53, and proliferative markers provide some clues as to the formation of several tumours. In this study the mechanism of the genesis of parathyroid adenomas was investigated using immunohistochemistry. Sections of parathyroid adenomas from 12 cases were stained using PCNA (proliferating cell nuclear antigen), EGFR, and p53 immunohistochemistry. Correlations between PCNA LI (labelling index), EGFR expression, p53 expression, age, serum parathormone, Ca and P levels, and tumour diameter were investigated. PCNA LI was 45.8±33.1 (mean±standard deviation) and all the cases were somewhat positive. Five cases (41.67 %) were EGFR positive. Maximum 10 % of the cells were positive in these cases. All the cases were p53 negative. There was a correlation between PCNA LI and serum parathormone level (r=0.607, p=0.036). According to these results, parathormone synthesis is high when the proliferative activity of parathyroid adenoma is high. Four of the five EGFR‐positive patients were below 35 years of age. These data may indicate that formation of parathyroid adenoma in young patients is related to a mechanism involving EGFR. Absence of p53 expression suggests that p53 mutation is not a common component of parathyroid adenomas.