A review on aflatoxin contamination and its implications in the developing world: a sub-Saharan African perspective

Mycotoxins contamination in some agricultural food commodities seriously impact human and animal health and reduce the commercial value of crops. Mycotoxins are toxic secondary metabolites produced by fungi that contaminate agricultural commodities pre- or postharvest. Africa is one of the continents where environmental, agricultural and storage conditions of food commodities are conducive of Aspergillus fungi infection and aflatoxin biosynthesis. This paper reviews the commodity-wise aetiology and contamination process of aflatoxins and evaluates the potential risk of exposure from common African foods. Possible ways of reducing risk for fungal infection and aflatoxin development that are relevant to the African context. The presented database would be useful as benchmark information for development and prioritization of future research. There is need for more investigations on food quality and safety by making available advanced advanced equipments and analytical methods as well as surveillance and awareness creation in the region.

Infestation and population dynamics of insects on stored cassava and yams chips in Benin, West Africa

Natural insect infestation in cassava (Manihot esculenta Crantz subspecies esculenta) and yam (Dioscorea spp.) chips was evaluated during two consecutive storage seasons (2003-2004 and 2004-2005) in two agroecological zones of Benin (Northern Guinea Savanna [NGS] and Sudan Savanna [SS]). The insects infesting chips were collected, identified, and counted, they included Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae), Cathartus quadricollis (Guerin) (Coleoptera: Silvanidae), Carpophilus dimidiatus (F.) (Coleoptera: Nitidulidae), Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). P. truncatus and C. quadricollis were observed with a higher prevalence on cassava than on yam chips. During both seasons after 3 mo of storage, all (100%) cassava chip samples were infested with P. truncatus and C. quadricollis in both agroecological zones, whereas yam chips only showed lower infestation rates of 59.5 and 19.1% for P. truncatus and C. quadricollis, respectively, at the end of storage in 2003-2004. During the 2004-2005 season after 3 mo of storage infestation rate in yam chips was 66 and 24% in NGS and 100 and 0% in SS for P. truncatus and C. quadricollis, respectively, showing that insect infestation levels vary significantly with commodity, year, and fluctuate during the storage season.

Mycoflora and natural occurrence of aflatoxins and fumonisin B1 in cassava and yam chips from Benin, West Africa

The presence of fungi, aflatoxins and fumonisin B1 in cassava and yam chips (during 28 processing and storage) were evaluated during two consecutive seasons in two agroecological zones of Benin (Northern Guinea Savannah, NGS and Sudan Savannah, SS). The Benin samples were assessed for moisture content, fungal infestation and total aflatoxin and fumonisin B1 contamination. During the two seasons, samples collected from the NGS, had moisture contents ranging from 10.0 to 14.7% in cassava chips and from 11.4 to 15.3% in yam chips. In samples from the SS, moisture content ranged from 10.1 to 14.5% and 11.1 to 14.5% in cassava and yam chips, respectively. A. flavus was the predominant fungal species. The maximum cfu/g in cassava and yam chips was 8950 and 6030, respectively. Other fungal species isolated included P. chrysogenum, M. piriformis, Phoma sorghina, F. verticillioides, R. oryzae and Nigrospora oryzae. High performance liquid chromatography analysis of both cassava and yam chips showed no contamination by either aflatoxins or fumonisin B1.

Public information campaign on aflatoxin contamination of maize grains in market stores in Benin, Ghana and Togo

Rotary International with the International Institute of Tropical Agriculture (IITA) conducted an information campaign from 2000 to 2004 to increase public awareness of aflatoxin in Benin, Ghana and Togo. Key informant interviews with 2416 respondents showed poor baseline knowledge of aflatoxin and its health risks. The campaign included monitoring of aflatoxin contamination in maize grains from market stores in 38 cities and towns. Aflatoxin concentration in contaminated samples ranged from 24 to 117.5 ng g(-1) in Benin, from 0.4 to 490.6 ng g(-1) in Ghana, and from 0.7 to 108.8 ng g(-1) in Togo. The campaign significantly increased public awareness that populations were exposed to high levels of aflatoxin. The number of maize traders who were informed about the toxin increased 10.3 and 3.2 times in Togo and Benin, respectively; at least 33% more traders believed the information in each of Benin and Togo; 11.4 and 28.4% more consumers sorted out and discarded bad grains in Benin and Ghana, respectively. This paper concludes that sustained public education can help reduce aflatoxin contamination.

Impact of mechanical shelling and dehulling on Fusarium infection and fumonisin contamination in maize

Mechanical shelling and dehulling methods were tested to evaluate their impact on Fusarium infection and fumonisin contamination in maize. All shelling methods which were tested were found to damage the grains. The IITA sheller caused the highest level (up to 3.5%) of damage. Fusarium populations were higher on damaged grains, the highest being recorded from grains damaged by the IITA sheller (2,533.3 cfu g(-1)). Fumonisin levels were higher in damaged grains, the highest being in maize shelled with the IITA sheller (2.2 mg kg(-1)). Fumonisin levels were positively and significantly correlated with the percentage of damage caused by the shelling methods, and with the number of Fusarium colonies in maize. Mechanical dehulling methods significantly reduced fumonisin levels in maize, resulting in a mean reduction of 62% for Mini-PRL, 65% for Engelberg, and 57% for the attrition disc mill. It is important for farmers to choose appropriate shelling methods to reduce mycotoxin contamination. Dehulling should be widely promoted for the reduction of mycotoxins in maize.

Dietary exposure to aflatoxin from maize and groundnut in young children from Benin and Togo, West Africa

Aflatoxins are a family of fungal toxins that are carcinogenic to man and cause immunosuppression, cancer and growth reduction in animals. We conducted a cross-sectional study among 480 children (age 9 months to 5 years) across 4 agro-ecological zones (SS, NGS, SGS and CS) in Benin and Togo to identify the effect of aflatoxin exposure on child growth and assess the pattern of exposure. Prior reports on this study [Gong, Y.Y.,Cardwell, K., Hounsa, A., Egal, S., Turner, Hall, A.J., Wild, C.P., 2002. Dietary aflatoxin exposure and impaired growth in young children from Benin and Togo: cross sectional study. British Medical Journal 325, 20-21, Gong, Y.Y., Egal, S., Hounsa, A., Turner, P.C., Hall, A.J., Cardwell, K., Wild, C.P., 2003. Determinants of aflatoxin exposure in young children from Benin and Togo, West Africa: the critical role of weaning and weaning foods. International Journal of Epidemiology, 32, 556-562] showed that aflatoxin exposure among these children is widespread (99%) and that growth faltering is associated with high blood aflatoxin-albumin adducts (AF-alb adducts), a measure of recent past exposure. The present report demonstrates that consumption of maize is an important source of aflatoxin exposure for the survey population. Higher AF-alb adducts were correlated with higher A. flavus (CFU) infestation of maize (p=0.006), higher aflatoxin contamination (ppb) of maize (p<0.0001) and higher consumption frequencies of maize (p=0.053). The likelihood of aflatoxin exposure from maize was particularly high in agro-ecological zones where the frequency of maize consumption (SGS and CS), the presence of aflatoxin in maize (SGS) or the presence of A. flavus on maize (NGS and SGS) was relatively high. Socio-economic background did not affect the presence of A. flavus and aflatoxin in maize, but better maternal education was associated with lower frequencies of maize consumption among children from the northernmost agro-ecological zone (SS) (p=0.001). The impact of groundnut consumption on aflatoxin exposure was limited in this population. High AF-alb adduct levels were correlated with high prevalence of A. flavus and aflatoxin in groundnut, but significance was weak after adjustment for weaning status, agro-ecological zone and maternal socio-economic status (resp. p=0.091 and p=0.083). Ingestion of A. flavus and aflatoxin was high in certain agro-ecological zones (SS and SGS) and among the higher socio-economic strata due to higher frequencies of groundnut consumption. Contamination of groundnuts was similar across socio-economic and agro-ecological boundaries. In conclusion, dietary exposure to aflatoxin from groundnut was less than from maize in young children from Benin and Togo. Intervention strategies that aim to reduce dietary exposure in this population need to focus on maize consumption in particular, but they should not ignore consumption of groundnuts.

Influence of substrate binding on the mechanical stability of mouse dihydrofolate reductase

We investigated the effect of substrate binding on the mechanical stability of mouse dihydrofolate reductase using single-molecule force spectroscopy by atomic force microscopy. We find that under mechanical forces dihydrofolate reductase unfolds via a metastable intermediate with lifetimes on the millisecond timescale. Based on the measured length increase of approximately 22 nm we suggest a structure for this intermediate with intact substrate binding sites. In the presence of the substrate analog methotrexate and the cofactor NADPH lifetimes of this intermediate are increased by up to a factor of two. Comparing mechanical and thermodynamic stabilization effects of substrate binding suggests mechanical stability is dominated by local interactions within the protein structure. These experiments demonstrate that protein mechanics can be used to probe the substrate binding status of an enzyme.

Natural occurrence of Fusarium and subsequent fumonisin contamination in preharvest and stored maize in Benin, West Africa

The natural occurrence of Fusarium and fumonisin contamination was evaluated from 1999 to 2003 in both preharvest and stored maize produced by small-scale farmers in four agroecological zones of Benin. Mycological analyses revealed a predominance of both Fusarium and Aspergillus in maize samples compared to other genera. The two Fusarium species most commonly isolated from maize were Fusarium verticillioides (68%) and Fusarium proliferatum (31%). Atypical isolates of F. verticillioides with some characteristics of Fusarium andiyazi but apparently closer to F. verticillioides, because the isolates were all high fumonisin producers, were also found only on preharvest maize. Study of F. verticillioides strains showed the presence of extremely high fumonisin producers in Benin with total fumonisin levels ranging from 8240 to 16,690 mg/kg. Apart from 2002-2003, Fusarium occurrence was not significantly different from one zone to another, although a slight decrease was observed from south, humid, to north, drier. Fusarium occurrence varied somewhat from one season to another. It significantly decreased over the 6 months of storage. Widespread fumonisin occurrence in maize was observed. Most of the maize samples collected were found positive for fumonisin with levels ranging from not detected to 12 mg/kg in 1999-2000, 6.7 mg/kg in 2000-2001 and 6.1 mg/kg in 2002-2003. Fumonisin levels in maize were found to be significantly higher in the two southern zones during all the surveys. The highest mean total fumonisin level was detected in 1999-2000 in maize samples from the southern Guinea Savannah (SGS) (12 mg/kg), whereas in both 2000-2001 and 2002-2003, it was in samples from the forest mosaic savannah (FMS) (6.7 and 6.1 mg/kg, respectively). Fumonisin levels varied from one season to another and, throughout the storage time, showing a decreasing trend in each zone. However, this decrease was not significant every season. An increasing trend was observed during some seasons in the SGS and northern Guinea Savannah (NGS) zones. The results of this study emphasise that farmers and consumers, not only in Benin but also in other West African countries, should be alerted to the danger of fumonisin contamination in maize.

Fate of aflatoxins and fumonisins during the processing of maize into food products in Benin

The fate of aflatoxins and fumonisins, two mycotoxins that cooccur in maize, was studied through the traditional processing of naturally contaminated maize in mawe, makume, ogi, akassa, and owo, maize-based foods common in Benin, West Africa. Levels of total aflatoxin and fumonisin were measured at the main unit operations of processing, and the unit operations that induce significant reduction of mycotoxin level were identified. Overall reduction of mycotoxin level was more significant during the preparation of makume (93% reduction of aflatoxins, 87% reduction of fumonisins) and akassa (92% reduction of aflatoxins, 50% reduction of fumonisins) than that of owo (40% reduction of aflatoxins, 48% reduction of fumonisins). Sorting, winnowing, washing, crushing combined with dehulling of maize grains were the unit operations that appeared very effective in achieving significant mycotoxin removal. Aflatoxins and fumonisins were significantly recovered in discarded mouldy and damaged grains and in washing water. Fermentation and cooking showed little effect. During the preparation of ogi and akassa, reduction of fumonisin levels measured in food matrix was lower (50%) compared to mawe and makume, probably due to significant fumonisin release in ogi supernatant. Consequently, the use of ogi supernatant for preparing beverages or traditional herbal medicines could be harmful as it is likely to be contaminated with mycotoxin from the raw maize.

Catalytic activity of caspase-3 is required for its degradation: stabilization of the active complex by synthetic inhibitors

The activation of caspase-3 represents a critical step in the pathways leading to the biochemical and morphological changes that underlie apoptosis. Upon induction of apoptosis, the large (p17) and small (p12) subunits, comprising active caspase-3, are generated via proteolytic processing of a latent proenzyme dimer. Two copies of each individual subunit are generated to form an active heterotetramer. The tetrameric form of caspase-3 cleaves specific protein substrates within the cell, thereby producing the apoptotic phenotype. In contrast to the proenzyme, once activated in HeLa cells, caspase-3 is difficult to detect due to its rapid degradation. Interestingly, however, enzyme stability and therefore detection of active caspase-3 by immunoblot analysis can be restored by treatment of cells with a peptide-based caspase-3 selective inhibitor, suggesting that the active form can be stabilized through protein-inhibitor interaction. The heteromeric active enzyme complex is necessary for its stabilization by inhibitors, as expression of the large subunit alone is not stabilized by the presence of inhibitors. Our results show for the first time, that synthetic caspase inhibitors not only block caspase activity, but may also increase the stability of otherwise rapidly degraded mature caspase complexes. Consistent with these findings, experiments with a catalytically inactive mutant of caspase-3 show that rapid turnover is dependent on the activity of the mature enzyme. Furthermore, turnover of otherwise stable active site mutants of capase-3 is rescued by the presence of the active enzyme suggesting that turnover can be mediated in trans.

Substrate cleavage by caspases generates protein fragments with Smac/Diablo-like activities

Smac/Diablo and HtrA2/Omi promote apoptosis by binding to and antagonizing IAP proteins, including the 'X chromosome-linked inhibitor of apoptosis' (XIAP). Here we show that caspase-mediated proteolysis of a limited subset of cell death substrates exposes functional Smac/Diablo-like N-termini after cleavage, which are able to bind to and antagonize XIAP. We propose that this mechanism may establish a feedforward sensitization of the apoptotic pathway and contribute to the functional redundancy of IAP antagonism. In addition, this may be particularly relevant in Alzheimer's disease since the caspase-generated C31 peptide, an established cytotoxin, acquires Smac/Diablo-like properties after apoptotic processing.

Mechanistic aspects of the de-novo synthesis of PCDD/PCDF on model mixtures and MSWI fly ashes using amorphous 12C- and 13C-labeled carbon

The formation of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) from amorphous 12C- and 13C-labeled carbon was studied on model mixtures and real fly ashes. PCDD/F can either be formed directly (de-novo) from carbon already present in fly ash or step-by-step via condensation of two aromatic rings. Using model mixtures containing 12C- and 13C-labeled carbon in various ratios we observed the formation of the following compound classes: 12C6-PCPh, -PCBz, 13C6-PCPh, -PCBz, 12C12-PCDD/ F, 13C12-PCDD/F, and 12C6 13C6-PCDD/F. By examining the fraction of the mixed PCDD/F (one of the two aromatic ring is composed solely of 12C-atoms while the other contains only 13C-atoms) in the total concentration of PCDD/F, conclusions on the formation of these three ring structures are possible. From the experimental results, it can be concluded that both reaction mechanisms are operative in the formation of PCDD/F from carbon. On fly ashes approximately half of the total amount of PCDD is formed via condensation of de-novo created C6-precursors e.g. chlorophenols, while the remainder is directly released (de-novo) from the carbon i.e., formed from a related C12-structure. However, the condensation of intermediate aromatic C6-precursors is of minor importance in the formation of PCDF. With increasing temperature the relative amount of the 12C6 13C6-PCDD formed by condensation decreases due to the faster evaporation of chlorophenols. At a constant reaction temperature, the ratio of both reaction pathways is hardly influenced by reaction time. In experiments with fly ashes doped with 13C-labeled carbon, this carbon isotope shows a similar reactivity as the native carbon present on the fly ash. Thus, the used amorphous carbons are suitable models for this investigation.

First Report of Aflatoxin in Dried Yam Chips in Benin

Dried yam (Dioscorea spp.) chips are widely consumed in Bénin but are often attacked by molds. Invasion of food by Aspergillus flavus may lead to aflatoxin contamination. We report here the result of a survey on the sanitary quality of dried yam chips in Bénin. During July and August 2000, 50 dried yam chips samples were collected from different points in the marketing chain; 10 samples were collected from each of 5 stages: producers, wholesalers, retailers, dried yam-based food sellers and consumers. Aflatoxin content was assayed by the bio-luminescence method (1) after methanol/water extraction. Aflatoxins were detected in all dried yam chip samples, with levels ranging from 2.2 to 200 ppb and a mean value of 14 ppb. An aflatoxin concentration higher than the European Union's maximum residue limit (MRL) of 4 ppb was found in 98% of the samples (N = 50), while 6% had an aflatoxin concentration higher than the World Health Organization's MRL of 20 ppb. Molds were analyzed from two samples, each with aflatoxin levels around 5 ppb, on colony unit medium specific for A. flavus (2). Aspergillus spp. were detected in the inner part of dried yam chips of both samples, with a mean level of 9,000 CFU/g. Fusarium colonies were also present but were not identified to species. References: (1) D. Champiat and J. Larpent. Bio-chimie-luminescence: Principes et Applications. Masson, Paris, France. 1993. (2) P. J. Cotty. Mycopathologia 125:157, 1994.

Regional distribution of ornithine decarboxylase activity and polyamine levels in experimental cat brain tumors

Biosynthesis of the polyamines putrescine, spermidine, and spermine, and activation of the first key enzyme ornithine decarboxylase (ODC) are closely associated with cellular proliferation. In the present study, the distribution of ODC activity and polyamine levels was investigated for the first time regionally in experimental brain tumors of the cat. Brain tumors were produced by stereotactic xenotransplantation of rat glioma cells. Twenty days after implantation, the brains were frozen in situ, cut into slices, and cryostat sections and tissue samples were taken to determine ODC activity and polyamine levels biochemically. The quantified data were color-coded to present the regional distribution of ODC activity and polyamine levels in the respective section. ODC activity significantly increased in some areas within the tumor, whereas peritumoral tissue showed no difference to the non-tumoral, contralateral hemisphere. This increase turned out in parallel to a high number of mitoses in the same tumor parts (r=0.861). Putrescine levels increased both, in the whole tumor and in the peritumoral edema. Regional differences in putrescine content did not correlate with solid and proliferative parts of the tumor. Spermidine and spermine levels were only slightly increased in some parts of the tumor. Thus, these experiments show the close correlation of a high mitotic rate and activation of ODC within experimental gliomas and underline the relevance of ODC as a biochemical marker of proliferation in brain tumors.

[Value of non-randomized prospective multicenter studies of perioperative antibiotic prophylaxis]

Non-randomized prospective multicenter studies involving a large number of patients are often capable to prove effectiveness of perioperative antimicrobial prophylaxis in situations where it is not feasible to carry out highly sophisticated clinical trials due to limitations in logistical or financial resources. Furthermore, these studies tend to give a true picture of the daily work and procedures in hospitals, contrary to controlled trials in clinical research which might suffer of multitudes of restrictions and exclusions. Some non-randomized studies each involving more than 1,000 patients on antibiotic prophylaxis in colonic and biliary surgery as well as appendectomy are discussed and its usefulness demonstrated.

Reactions of 2,4,6-trichlorophenol on model fly ash: oxidation to CO and CO2, condensation to PCDD/F and conversion into related compounds

Thermal treatment of 2,4,6-trichlorophenol on a magnesium silicate-based model fly ash in the temperature range between 250 degrees C and 400 degrees C leads predominantly to carbon monoxide and carbon dioxide. The fraction of 2,4,6-trichlorophenol which is oxidized to CO and CO2 increases from 3% at 250 degrees C to 75% at 400 degrees C. Further products are polychlorinated benzenes, dibenzo-p-dioxins, dibenzofurans and phenols. The homologue and isomer patterns of the chlorobenzenes suggest chlorination in the ipso-position of the trichlorophenol. The formation of PCDD from 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol on municipal solid waste incinerator fly ashes and model fly ash were compared and the reaction order calculated.

Dioxins from thermal and metallurgical processes: recent studies for the iron and steel industry

In thermal metallurgical processes such as iron ore sintering and metal smelting operations, large flows of off-gases are generated. Mainly due to residue recycling in such processes, chlorine and volatile organics are always present in the feed. As a consequence of "de novo" formation, the off-gases from such processes typically contain dioxins in the range 0.3-30 ng I-TEQ/Nm3. So far there are only very few studies about the mechanisms of dioxin formation and destruction in these metallurgical processes. In an European Union (EU) research project "Minimization of dioxins in thermal industrial processes: mechanisms, monitoring and abatement (MINIDIP)", integrated iron and steel plant has been selected as one of the industrial sectors for further investigation. A large number of particulate samples (feed, belt siftings, electrofilter) were collected from the iron ore sintering installations from various steel plants and analyzed for their organochlorocompound contents. Measurable amounts of PCDD/F, PCBz, PCB were found for all samples. The various parameters influencing their de novo synthesis activity were also evaluated in laboratory experiments, and such activity was found to be moderate for samples from the ore sinter belt, but extremely high for some ESP dusts. Fine dust is active in a wide range of temperatures starting at 200 degrees C and declining above 450 degrees C; the optimal temperature for de novo synthesis was found to be around 350 degrees C; some inhibitors, such as triethanolamine, may reduce de novo activity by 50%, and lowering the O2 concentration in the gas stream leads to a much lower amount of PCDD/F formation. On the basis of their relative mass, typical operating conditions and specific activity of the different samples, the regions in the sintering plant where de novo synthesis may take place were tentatively established.

The influence of storage practices on aflatoxin contamination in maize in four agroecological zones of Benin, west Africa

Aflatoxin level in 300 farmers' stores in four agro-ecological zones in Benin, a west African coastal country, were determined over a period of 2 years. At sampling a questionnaire was used to evaluate maize storage practices. Farmers were asked what storage structure they used, their storage form, storage period, pest problems in storage and what was done against them. Beninese farmers often changed their storage structures during the storage period, transfering the maize from a drying or temporary store to a more durable one. Most of the farmers complained about insects damaging stored maize. Often, storage or cotton insecticides were utilized against these pests. Regression analysis identified those factors that were associated with increased or reduced aflatoxin.Maize samples in the southern Guinea and Sudan savannas were associated with higher aflatoxin levels and the forest/savanna mosaic was related to lower toxin levels. Factors associated with higher aflatoxin were: storage for 3-5 months, insect damage and use of Khaya senegalensis-bark or other local plants as storage protectants. Depending on the agroecological zone, storage structures that had a higher risk of aflatoxin development were the "Ago", the "Secco", the "Zingo" or storing under or on top of the roof of the house. Lower aflatoxin levels were related to the use of storage or cotton insecticides, mechanical means or smoke to protect against pests or cleaning of stores before loading them with the new harvest. Fewer aflatoxins were found when maize was stored in the "Ago" made from bamboo or when bags were used as secondary storage containers.

Beta-endorphin (1-31) in the plasma of male volunteers undergoing physical exercise

beta-Endorphin is an opioid peptide representing the C-terminal 31 amino acid residue fragment of proopiomelanocortin (POMC). The release of beta-endorphin from the pituitary into the cardiovascular compartment under physical or emotional stress has been frequently reported. However, besides beta-endorphin (1-31), nine acetylated or non-acetylated beta-endorphin analogues exist - in addition to N-terminally elongated beta-endorphin derivatives such as beta-lipotropin (beta-LPH). Since conventional radioimmunoassays (RIAs) and even commercially available two site-RIAs pick up at least some of those beta-endorphin derivatives, only "beta-endorphin immunoreactive materials" and not authentic beta-endorphin have been determined in those studies. We have developed a highly specific two site-RIA for beta-endorphin (1-31), which does not cross-react with all beta-endorphin derivatives known to occur as yet. Using this RIA as well as further assays for determination of beta-endorphin (1-31), beta-endorphin immunoreactive material (IRM), ACTH and Cortisol in the plasma of 14 volunteers upon intensive physical exercise, we found authentic beta-endorphin only in about 50% of the plasma samples, representing therein only a minor portion of the beta-endorphin IRM.

Spontaneous regression of HIV associated T-cell non-Hodgkin's lymphoma with highly active antiretroviral therapy

A subcutaneous, T-phenotypic anaplastic large cell lymphoma (CD30/Ki1-positive, EBV positive) was diagnosed in a HIV-infected bisexual man. Without chemotherapy the patient had a sustained long-term remission of this tumor (more than three years) after the initiation of highly active antiretroviral therapy. By PCR analysis of T-cell receptor beta gene rearrangements the tumor was found to be oligoclonal. Improvement of cellular immune function by antiretroviral therapy is the only recognizable factor which may have led to tumor remission. This hypothesis is supported by parallels to EBV associated polyclonal lymphoproliferation in allogeneic transplantat recipients where regression of lymphoma can be induced by reducing immunosuppressive therapy.

Comparison of 2,4,6-trichlorophenol conversion to PCDD/ PCDF on a MSWI-fly ash and a model fly ash

We performed experiments on two different matrices with 2,4,6-trichlorophenol as precursor to Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD)/F. A municipal solid waste incinerators (MSWI) and a model fly ash were spiked in two different ways. The experiments demonstrated a three times higher formation potential of the trichlorophenol to PCDD on MSWI fly ash compared with the model fly ash used. For both fly ashes the PCDD yield was higher when gaseous trichlorophenol was fed continuously compared to mixing the fly ashes prior to the experiments with the total amount of the precursor. Despite dilution of the fly ashes tenfold with an inactive matrix the conversion of the chlorophenol was very high.

CMV sinusitis as the initial manifestation of AIDS

Cytomegalovirus (CMV) disease is a typical late-stage complication of AIDS. Only six cases of CMV sinusitis have been reported in the literature. This is the first case of CMV sinusitis leading to the diagnosis of HIV and CMV retinitis. Diseases of the sinonasal tract may represent an initial manifestation of HIV or AIDS.

Identification of Cox20p, a novel protein involved in the maturation and assembly of cytochrome oxidase subunit 2

We have identified Cox20p, a 23.8-kDa protein of the mitochondrial inner membrane that is involved in the biogenesis of the yeast cytochrome oxidase complex. Cytochrome oxidase subunit 2 (Cox2p) accumulates as a precursor in cox20 mutants, suggesting a defect in biogenesis of this mitochondrially encoded protein. The inability of cox20 mutants to process the subunit 2 precursor (pCox2p) is not due to impaired export of the protein across the inner membrane or to an inactive Imp1p/Imp2p peptidase. Rather, Cox20p specifically binds the newly synthesized pCox2p, a step required to present the exported pCox2p as a substrate to the Imp1p peptidase. All of the endogenous pCox2p accumulated in an Deltaimp1 mutant, and a small fraction of Cox2p in wild type yeast, is detected in a complex with Cox20p. Following maturation Cox2p remained associated with Cox20p, prior to assembling into the cytochrome oxidase complex. We propose that Cox20p acts as a membrane-bound chaperone necessary for cleavage of pCox2p and for interaction of the mature protein with other subunits of cytochrome oxidase in a later step of the assembly process.

Treatment of refractory Hodgkin's lymphoma patients with an anti-CD25 ricin A-chain immunotoxin

The anti-CD25 immunotoxin RFT5.dgA was constructed by coupling the monoclonal antibody RFT5 via a sterically hindered disulfide linker to deglycosylated ricin A-chain and was administered to patients with relapsed Hodgkin's lymphoma in four bolus infusions over 7 days (day 1, 3, 5 and 7). The maximum tolerated dose in these patients as defined in a previous phase I study was 15 mg/m2. Subsequently, further patients were enrolled at the maximum tolerated dose and a total of 18 patients were treated at this level. All patients had signs of progressive disease and were heavily pretreated. Side-effects in this trial were moderate and related to vascular leak syndrome. Five of 18 patients experienced NCI grade III toxicities including weakness, edema, dyspnea, and myalgia. Eleven of 16 (69%) patients receiving two or more cycles produced human anti-ricin antibodies and human anti-mouse antibodies (>/=1.0 microg/ml). Seventeen of 18 patients were evaluable for clinical response. These included two partial remissions. One patient demonstrated minor response and five patients stable diseases. We conclude that RFT5.dgA is of moderate clinical efficacy in this group of heavily pretreated refractory patients. Leukemia (2000) 14, 129-135.

Bcs1p, an AAA-family member, is a chaperone for the assembly of the cytochrome bc(1) complex

Bcs1p, a mitochondrial protein and member of the conserved AAA protein family, is involved in the biogenesis of the cytochrome bc(1) complex. We demonstrate here that Bcs1p is directly required for the assembly of the Rieske FeS and Qcr10p proteins into the cytochrome bc(1) complex. Bcs1p binds to a precomplex in the assembly pathway of the cytochrome bc(1) complex. Binding of Bcs1p to and release from this assembly intermediate is driven by ATP hydrolysis. We propose that Bcs1p acts as an ATP-dependent chaperone, maintaining the precomplex in a competent state for the subsequent assembly of the Rieske FeS and Qcr10p proteins.

Expression of epstein-barr virus nuclear antigen 1 is associated with enhanced expression of CD25 in the Hodgkin cell line L428

Epstein-Barr virus is associated with several human malignancies including Burkitt's lymphoma, nasopharyngeal carcinoma, and Hodgkin's disease (HD). To examine the effect of Epstein-Barr virus nuclear antigen 1 (EBNA-1) in the pathogenesis of HD, we transfected the gene into the HD cell line L428. EBNA-1 expression was associated with significantly enhanced CD25 expression (interleukin 2 [IL-2]-receptor alpha chain) in transient and stably transfected L428 cells but did not affect the expression of IL-2 receptor beta and gamma chains. There was no up-regulation of the B-cell activation molecules CD23, CD30, CD39, CD40, CD44, CD71, and CD54 (intercellular adhesion molecule 1) or enhanced production of IL-6, IL-10, lymphotoxin alpha, and the soluble form of CD25. Stable EBNA-1-expressing L428 cells were nontumorigenic in SCID mice but showed enhanced lymphoma development in nonobese diabetic-SCID mice compared to mock-transfected cells.

[Antibiotic prophylaxis in appendectomy. Often neglected--but necessary!]

For several decades it has been proven that adequate antimicrobial prophylaxis is effective in reducing postoperative septic complications also in appendectomy. The rational for this approach--including laparoscopic procedures--is discussed and national and international recommendations for antibiotic prophylaxis in appendectomy are cited. Unfortunately, in spite of all the evidence, less than 50% of all appendectomies in 1996 in Germany had been carried out under antibiotic cover--with serious consequences for many patients and increased costs for prolonged hospital stay and treatment due to the higher incidence of infectious postoperative complications. Surgeons are encouraged not to neglect facts and benefits concerning the use of appropriate prophylactic antimicrobials in all appendectomies.

Leiomyosarcomas of the female genital tract: a clinical and histopathological study

INTRODUCTION

Leiomyosarcomas are malignant tumours showing smooth muscle differentiation. They represent approximately 25% of all uterine sarcomas and slightly over 1% of all uterine malignancies. The purpose of the present retrospective review is to relate clinical and pathological findings of leiomyosarcomas of the female genital tract to prognosis.

MATERIAL AND METHODS

During 1972-1992 eleven patients had diagnosed uterine leiomyosarcomas treated at the Department of Gynecology of the University of Saarland. The hospital records of all patients were reviewed and complete primary treatment had been performed at this center.

RESULTS

The mean age was 46.92 years (SD: +/-13.85). Atypical uterine bleeding and pelvic discomfort were the most common presenting complaints (72.7%). The mean follow-up time was 59.60 months (20-96 months). Overall 2-year survival was 70% and overall 5-year survival 30%. The overall survival of patients in FIGO-stage I was 57.14%, in FIGO-stage II 100%, in FIGO-stage III 0% and in FIGO-stage IV 0%.

CONCLUSION

The primary therapy should consist of an operation as radical as possible. Treatment with organ preserving seems to be reasonable if the patient desires children. Also, chemotherapy might provide a hopeful sign in the improvement of survival rates.

[Antibiotic prophylaxis in cholecystectomy--necessary and cost saving?]

The effectiveness of antimicrobial prophylaxis was evaluated on the basis of data collected in a study on quality management carried out in 28 East German hospitals, involving 4477 laparoscopic and conventional cholecystectomies (197 of which with revision of the common bile duct). In 3128 patients a laparoscopic procedure (with consecutive conversion to an open cholecystectomy in 236 cases) and in 1349 patients a primarily conventional open cholecystectomy had been performed (a total of 2217 cases with and 2260 cases without antibiotic cover). The results obtained were significantly better in the group receiving prophylaxis than in patients not under antimicrobial cover. This applied to septic wound healing disorders, general and specific postoperative complications, postoperative chest infections, re-operations and postoperative lethality. On the basis of these results, it is strongly recommended that, in the future, neither laparoscopic nor open conventional cholecystectomy should be carried out without proper perioperative antimicrobial prophylaxis-this all the more so since such measures also result in a shorter hospital stay and thus reduced costs.

Oxa1p, an essential component of the N-tail protein export machinery in mitochondria

A number of nuclear encoded inner membrane proteins of mitochondria span the membrane in such a manner that their N termini are located in the intermembrane space. Many of these proteins attain this membrane orientation by undergoing an export step from the matrix across the inner membrane. This export process, which resembles bacterial N-tail export from energetic and topogenic signal requirements, is facilitated by Oxa1p, a protein that has homologues throughout prokaryotes and eukaryotes. Oxa1p, as we have previously shown, is required to export the N and C termini of the mitochondrially encoded pCoxII to the intermembrane space. We demonstrate here that imported nuclear encoded proteins physically interact with Oxa1p and depend on Oxa1p for efficient export of their N termini to the intermembrane space. Furthermore, Oxa1p interacts with nascent polypeptide chains synthesized in mitochondria, including the fully synthesized pCoxII and CoxIII species. Thus, Oxa1p represents a component of a general export machinery of the mitochondrial inner membrane.

Oxa1p mediates the export of the N- and C-termini of pCoxII from the mitochondrial matrix to the intermembrane space

Oxa1p is a mitochondrial protein reported to be involved in the assembly of the cytochrome oxidase complex. In the absence of a functional Oxa1p, subunit II of the cytochrome oxidase accumulates as its precursor form (pCoxII). Using mitochondria isolated from a yeast strain bearing a temperature sensitive mutation in the Oxa1p, pet ts1402, we have analyzed the function of the Oxa1p protein. We demonstrate that the accumulation of pCoxII in the pet ts1402 mitochondria does not reflect a compromised Imp1p activity in this mutant. Furthermore, measurement of the membrane potential has shown it to be sufficient to support the export of CoxII from the matrix. Rather, we found that newly synthesized pCoxII accumulates in the matrix of the pet ts1402 mitochondria, because export across the inner membrane is inhibited in the pet ts1402 mitochondria. In conclusion, Oxa1p mediates the export of the N- and C-termini of the mitochondrially encoded subunit II of cytochrome oxidase from the matrix to the intermembrane space.

Aspergillus flavus Infection and Aflatoxin Contamination of Preharvest Maize in Benin

Eighty and sixty maize fields were sampled in 1994 and 1995, respectively, to monitor Aspergillus infection and aflatoxin contamination of preharvest maize in Benin. Three Aspergillus species were isolated from different agroecological zones, with A. flavus being the most prevalent. The countrywide mean percentage of kernel infection was about 20% in both years. Aflatoxin was extracted from maize in at least 30% of the fields sampled. Toxin concentrations exhibited a distinct zonal variation, with relatively high levels in the Guinea Savanna. There was a trend toward higher rate of aflatoxin accumulation per percentage A. flavus infection from the south to the north. Damage by the ear borer, Mussidia nigrivenella, increased aflatoxin accumulation in maize. Hence, the geographic pattern observed in the occurrence of A. flavus and aflatoxin may be related to the incidence of M. nigrivenella.

Expression of Gal beta 1-4GlcNAc sequences by human gastrointestinal neoplasms and their precursors as detected by Erythrina cristagalli and Erythrina corallodendron lectins

Lectins from Erythrina cristagalli (EGA) and Erythrina corallodendron (ECorA) are well-known to detect type 2 chain oligosaccharides (Gal beta 1-4GlcNAc). These carbohydrate moieties are the biosynthetic precursors of various ABH and Lewis blood group antigens and are therefore also related to tumor-associated carbohydrate antigens. For this reason, we investigated the expression of ECA and ECorA binding sites in a series of gastric, colorectal and pancreatic carcinomas as well as corresponding normal tissues. Additionally, a series of hyperplastic and adenomatous colorectal polyps was analyzed. According to our results, both lectins exhibited a strong reactivity with the great majority of gastrointestinal carcinomas. Regarding gastric carcinomas, a stronger reactivity with intestinal-type compared to the diffuse-type species could be observed. Some poorly differentiated tumors were not or only very faintly stained. In the case of colorectal carcinomas, liver metastases which were investigated comparatively, exhibited the same binding pattern as the primary tumors. Colorectal adenomas were stained in about half of the cases without significant relation to the grade of cellular atypia. Positivity observed in normal epithelia (i.e, gastric superficial epithelia, fundus neck cells and deep pyloric mucous glands, pancreatic acini and ductal structures) is in keeping with histogenetic relations between these normal histological structures and corresponding neoplasms. In areas exhibiting intestinal metaplasia, various portions showed cytoplasmic staining of columnar cells and/or of goblet cell vacuoles. On the other hand, columnar and goblet cells in normal colorectal tissue were only weakly stained in a number of specimens. Therefore, it can be concluded that Gal beta 1-4GlcNAc is overexpressed in neoplastic colorectal tissues. Summarized, ECA and ECorA are suitable tools to analyze the expression of Gal beta 1-4GlcNAc, the common precursor substance of various tumor-associated type 2 chain antigens in neoplastic tissues.

Combination of Hodgkin's disease and diffuse large cell lymphoma: an in situ hybridization study for immunoglobulin light chain messenger RNA

It is not clear whether the rare combination of Hodgkin's diseases with non-Hodgkin lymphomas are true composite lymphomas or differentiation stages of one tumour cell clone. We used in situ hybridization and immunohistochemistry for the demonstration of immunoglobulin light chains in order to investigate the relationship between the two lymphoma components. In three cases of nodular lymphocyte predominance Hodgkin's disease combined with diffuse large B-cell lymphoma the Hodgkin cells, as well as the tumour cells in the diffuse large B-cell lymphoma, showed the same messenger RNA for one light chain. Thus, using in situ hybridization in nodular lymphocyte predominance Hodgkin's disease combined with diffuse large B-cell lymphoma in a small number of cases a possible genetic relationship between the two components could be shown. In nodular sclerosis combined with diffuse large B-cell lymphoma, in situ hybridization did not support a common clonal origin of both tumour parts. However, a unique clonal derivation cannot be excluded by the techniques applied.

Hodgkin cells accumulate mRNA for bcl-2

BACKGROUND

The bcl-2 oncogene is able to prevent cells from apoptosis. Overexpression of the bcl-2 protein seems to be important for the pathogenesis of follicular center cell lymphomas, in which both protein and mRNA usually show high levels. In addition, the expression of the Epstein-Barr virus-encoded late membrane protein up-regulates the bcl-2 protein in cell lines. The aim of the current study was to investigate the expression of the bcl-2 oncogene in Hodgkin's disease both at the protein and mRNA level in correlation with the expression of the late membrane protein.

EXPERIMENTAL DESIGN

Thirteen cases of all histologic types of Hodgkin's disease, six cases of chronic nonspecific lymphadenitis, three tonsils with follicular hyperplasia, seven cases of follicular small cleaved cell lymphoma, and six cases of follicular large cell lymphoma, were analyzed. We designed a novel digoxigenin-labeled oligonucleotide probe complementary to bcl-2 mRNA for nonisotopic in situ hybridization. Bcl-2 oncoprotein and late membrane protein expression were determined by immunohistochemistry. The presence of the 14;18 translocation was analyzed by PCR for the major breakpoint region.

RESULTS

The main finding was that, irrespective of subtype, the vast majority of Hodgkin cells express abundant bcl-2 mRNA. Oncoprotein expression, however, varied from case to case, with the highest prevalence in the nodular sclerosing subtype, and showed no strict correlation with the late membrane protein. In our case, no 14;18 translocation could be found in Hodgkin's disease.

CONCLUSIONS

Hodgkin cells in all types of Hodgkin's disease demonstrated high levels of bcl-2 mRNA, while the bcl-2 protein expression was inhomogenous. In nodular lymphocyte predominant type, the bcl-2 mRNA and protein pattern is comparable to germinal center cells. This finding is a further argument for the germinal center cell origin of this type of Hodgkin's disease.

[Hodgkin cells are clonal B-cells in various stages of differentiation]

Hodgkin's disease, especially its biology and pathogenesis, has been under discussion for more than 160 years. Numerous investigations have focused on the nature and clonality of Hodgkin cells, but so far no definitive answer have been yielded by immunohistochemistry, Southern blotting and PCR. However, the use of single-cell PCR has now made it possible to answer the question of the derivation of Hodgkin cells. Using a micromanipulator, Hodgkin cells can be picked out of histological sections and B-cell specific gene rearrangements (VDJ) can be amplified. With this technique it has proved possible to demonstrate the B-cell derivation of Hodgkin cells and their clonality. Mutated immunoglobulin genes in lymphocyte-predominant Hodgkin's disease indicate a germinal center cell origin of Hodgkin cells of this type. These findings, however, do not exclude cases of Hodgkin's disease with Hodgkin cells with a T-cell genotype.

Reactive versus neoplastic monocytoid B-cell proliferations. In situ hybridization study of immunoglobulin light chain mRNA

To distinguish reactive versus neoplastic monocytoid B-cell (MBC) proliferations, the clonality of MBC was examined in paraffin-embedded tissues by in situ hybridization (ISH) of immunoglobulin (Ig) light chain messenger RNA (mRNA) with sensitive oligonucleotide probes in 26 cases. They included 13 cases of lymphadenitis with MBC reaction and 13 cases of nodal (n = 8) and extranodal (n = 5) monocytoid B-cell lymphoma (MBCL). Two cases represented a composite lymphoma showing a centroblastic-centrocytic and MBCL component. The clonality of MBC infiltrates could be demonstrated in 16 of 26 (61.5%) cases by immunostaining for Ig light chains and in all (100%) cases by ISH. Neoplastic MBC usually expressed a faint-to-moderate light chain restriction of mRNA, whereas some MBC (10% to 30% of total MBCL population) showed a strong positivity irrespective of plasmacytoid differentiation as indicated by Ig immunostaining (present in 9 of 13 cases). Reactive MBC expressed a faint kappa and lambda light-chain mRNA positivity. Five percent to 20% of total reactive MBC showed also a strong positivity for both Ig light chain mRNA, although only a minor part of these cells (7 of 13 cases) expressed polyclonal Ig by immunohistochemistry. These results indicate that (1) both reactive and neoplastic MBC can differentiate into plasma cells; and (2) a relatively high percentage of reactive and neoplastic MBC show a detectable mRNA transcription, but not a corresponding Ig synthesis. Either the Ig detection is not sensitive enough or these cells might be in an early differentiation phase, where the Ig production has not yet started.

Incidence of Epstein-Barr virus bcl-2 expression and chromosomal translocation t(14;18) in large cell lymphoma associated with paragranuloma (lymphocyte-predominant Hodgkin's disease)

Seven cases of large cell lymphoma (LCL) developing simultaneously or secondarily to lymphocyte-predominant Hodgkin's disease (nodular paragranuloma [NP]) were investigated for the presence of Epstein-Barr virus genomic material and the chromosomal translocation t(14;18) involving the major breakpoint region of the bcl-2 gene using the polymerase chain reaction on paraffin-embedded material. The translocation t(14;18) and Epstein-Barr virus could not be demonstrated in any case. The expression of the bcl-2 oncogene product was investigated using immunohistochemistry. Only in one case were the lymphocytic and histiocytic cells positively stained with the bcl-2 antibody, whereas the associated LCL demonstrated a completely negative immunoreaction. In another case the LCL had a positive immunoreaction with this antibody and the corresponding lymphocytic and histiocytic cells were completely negative. We conclude that Epstein-Barr virus infection is rare or absent in NP and in the LCLs associated with NP. The chromosomal translocation t(14;18) does not seem to be a factor in the transformation of NP into LCL.

Demonstration of light chain mRNA in Hodgkin's disease

The lineage of Hodgkin and Reed-Sternberg cells is still unclear. Detection of both immunoglobulin light chains in Hodgkin and Reed-Sternberg cells by immunohistochemistry is a well-known phenomenon. However, up to now, in situ hybridization techniques have failed to demonstrate light chain messenger(m) RNA in Hodgkin and Reed-Sternberg cells. In this investigation, we have analysed 26 cases of Hodgkin's disease (nodular lymphocyte predominant Hodgkin's disease, mixed cellularity, and nodular sclerosis type) using digoxigenin-labelled oligonucleotide probes for kappa and lambda light chains by in situ hybridization. In nearly half of the cases of nodular lymphocyte predominant Hodgkin's disease and in one case of mixed cellularity type, mRNA for only one light chain could be clearly demonstrated in the lymphocytic and histiocytic cells, Hodgkin, and Reed-Sternberg cells. These results support the idea that at least some cases of Hodgkin's disease are B-cell neoplasms.

Expression of the proliferating cell nuclear antigen in the different types of Hodgkin's disease

Thirty-eight cases of Hodgkin's disease (HD, lymphocyte-predominant, n = 10; nodular sclerosis, n = 10; mixed cellularity, n = 10; lymphocyte depletion, n = 8) were investigated with the antibody PC10 directed against the proliferating cell nuclear antigen (PCNA) with B- and T-cell markers using a double-staining technique in paraffin-embedded material. It could be shown that nearly all (95-97%) Hodgkin's and Reed-Sternberg (HRS) cells and their variants were PCNA-positive regardless of the type of HD. There was only a low number of PCNA-positive lymphocytes (2.8-3.4%) in all types mostly consisting of MT1-positive T lymphocytes. In contrast to the other types, lymphocyte-predominant type showed a relatively high percentage (5%) of Leu-7-positive lymphocytes. The high percentage of PCNA-positive HRS cells correlates with their malignant nature, and might be another example of dysregulated expression of PCNA.

Doppler ultrasound of the subclavian artery as an aid to quantification of aortic insufficiency

Aortic insufficiency (AI) induces backflow of blood in the arterial system that is most pronounced in the major arteries close to the heart. Assuming that the intensity of the arterial backflow of blood may reflect the severity of AI, the systolic and diastolic flow profiles of the subclavian artery were studied in 40 patients with and 10 patients without AI that was angiographically proved by use of continuous wave Doppler ultrasound (8 MHz transducer, supraclavicular approach). Patients with angiographically determined severe AI (n = 17) had significantly higher diastolic regurgitant flow velocities (V-max) than patients with only mild (n = 9) or moderate (n = 14) degrees of AI (Severe AI = 35.0 +/- 12.0 cm/sec, moderate AI = 16.8 +/- 3.9 cm/sec, mild AI = 7.4 +/- 2.6 cm/sec; p < 0.01) and also showed significantly higher values with regard to the time velocity integral of the regurgitant jet (severe AI = 13.8 +/- 5.6 cm; moderate AI = 5.7 +/- 2.4 cm, mild AI = 1.4 +/- 0.9 cm; p < 0.01). After classification by jacknife discrimination analysis, the Doppler ultrasound grading was compared with a corresponding three-point scale (mild, moderate, severe) from aortic root angiography. A correct estimation of the severity of AI was possible in 44 of 50 patients (88%; overestimation in one, underestimation in five) and in 41 of 50 patients (83%; overestimation in one, underestimation in eight) with regard to V-max and the time velocity integral of the regurgitant jet, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)