[Lung ultrasound in patients with SARS-CoV-2 infection]

After taking a patient's history and physical examination, lung ultrasound can immediately reveal numerous causes and complications in patients suffering from respiratory tract infection and/or dyspnea. It can thus facilitate decisions on further diagnostic and first therapeutic procedures, even in patients with a SARS-CoV‑2 infection who present to the emergency room. This review article highlights the typical findings of lung ultrasound in patients with COVID-19 and discusses its value compared to other imaging methods.

Margin of safety of pentylene glycol derived using measurements of cutaneous absorption and volatility

The safety assessment of pentylene glycol (PG) has been based on a bioavailability extrapolated from those of other 1,2-glycols or an assumed 100% absorption. To make a better safety assessment and an accurate calculation of the margin of safety (MoS), the skin penetration of PG present in a commercially available sunscreen was measured in pig skin at different exposure durations. The mass balance of PG decreased with increasing exposure durations, from 98% (1 h) to 29% (24 h) and the amount of PG detected in the skin wash decreased over time from 93% to 3%. The decrease in mass balance was attributed to an unexpected volatility of PG, which was confirmed in additional experiments. The maximum bioavailable amount of PG was 123 μg/cm2 after 24 h and was considered to be worst case scenario (10 mg/cm² i.e. 5-fold the recommended application standard dose, 2 mg/cm²). MoS values for the application of a standard dose of sunscreen after 1-24 h exposure were 140-671 in adults and, if calculated for children ratios, 87-217 Based on the available toxicological data for PG in comparison to the amounts determined to be potentially bioavailable, PG in the test sun protection product SPF 50 + does not show any safety concerns for daily usage at the recommended dosage of 2 mg/cm² or lower.

Benefit of Contrast-Enhanced Ultrasound (CEUS) in the Follow-Up Care of Patients with Colon Cancer: A Prospective Multicenter Study

PURPOSE

According to the German guidelines on colorectal cancer, unenhanced ultrasound is recommended for follow-up. On the other hand, ultrasound and radiology societies specify the use of contrast-enhanced ultrasound for ruling out liver metastases. Studies focusing on the follow-up of cancer patients are lacking. The goal of this multicenter study initiated by the German Ultrasound Society (DEGUM) was to determine the potential benefit of contrast-enhanced ultrasound in the follow-up of patients with colon cancer.

MATERIALS AND METHODS

Follow-up patients with colon cancer (UICC > IIa) were investigated. As scheduled according to the German guidelines, unenhanced ultrasound was performed followed by contrast-enhanced ultrasound. All liver lesions were recorded. In case of additional metastases detected on contrast-enhanced ultrasound, contrast-enhanced CT, MRI or biopsy was performed to confirm additional liver metastases.

RESULTS

A total of 45 liver metastases were detected in 26/290 patients (= 9 %) using unenhanced ultrasound. A further 28 metastases were detected on contrast-enhanced ultrasound in these 26 patients. In 18 patients showing no liver metastases, 40 additional metastases were detected on unenhanced ultrasound. This means that 44 patients with a total of 113 liver metastases were detected on contrast-enhanced ultrasound (p = 0.0006).

CONCLUSION

Contrast-enhanced ultrasound should be recommended in the follow-up of patients with colon cancer in addition to unenhanced ultrasound - the up-to-date standard.

Importance of Abdominal Ultrasound in 17 Patients with Histologically Confirmed Autoimmune Pancreatitis (AIP)

PURPOSE

Autoimmune pancreatitis (AIP) is an independent, underdiagnosed, rare form of chronic pancreatitis. The goal of this study is to document ultrasound findings in histologically confirmed AIP in order to determine the diagnostic value of ultrasound.

MATERIALS AND METHODS

6 of 74 DEGUM instructors for internal medicine (level 3 and 2) provided anonymized clinical and sonographic data from 17 patients with histologically confirmed AIP.

RESULTS

9/17 patients had diffuse AIP, 8/17 had focal AIP, 14/17 suffered from upper abdominal pain, 9/17 had jaundice, and 3/9 had an elevated IgG4 level. Ultrasound showed diffuse hypoechoic organ enlargement in 9/17 cases and a hypoechoic tumor with an unclear border in 8/17 cases. AIP was verified by ultrasound-guided percutaneous core biopsy in 14 cases, by biopsy of the bile duct in 1 case, and by surgical biopsy in 2 cases. Involvement of the hepatobiliary system was present in 7/17 patients and autoimmune cholangitis was verified in 5 cases. All patients experienced remission after immunosuppressive treatment. The pancreatic duct had a normal width in 11 cases, was dilated in 5 cases, and was stenosed over a long stretch in 3 cases. Contrast-enhanced ultrasound did not show uniform signal increase but also no significantly reduced or absent perfusion.

CONCLUSION

Ultrasound can be diagnostically useful if the clinical manifestations of AIP are known. While the diffuse form allows an ad-hoc suspected diagnosis, the focal form can only be suspected in the case of additional extrapancreatic involvement. Contrast-enhanced ultrasound (CEUS) contributes greatly to the differentiation from ductal adenocarcinoma in the case of focal AIP.

Incidence of bleeding in 8172 percutaneous ultrasound-guided intraabdominal diagnostic and therapeutic interventions - results of the prospective multicenter DEGUM interventional ultrasound study (PIUS study)

PURPOSE

To analyse the incidence of bleeding after percutaneous ultrasound guided diagnostic and therapeutic intraabdominal interventions in a prospective multicentre study (DEGUM percutaneous interventional ultrasound study).

MATERIALS AND METHODS

Within a time period of 2 years diagnostic and therapeutic intraabdominal interventions (with the exclusion of ascites paracentesis) performed percutaneously under continuous ultrasound (US) guidance were prospectively assessed using a pseudonymized standardized web site entry form. Number and type of intervention, operator experience, patient characteristics, medication, lab data as well as technical aspects of the procedure and bleeding complications were analysed according to the interventional radiology standards.

RESULTS

8172 US-guided intraabdominal interventions (liver n = 5903; pancreas n = 501, kidney n = 434, lymph node = 272, biliary system n = 153, spleen n = 63, other abdominal organs and extra-organic targets n = 999) were analysed in 30 hospitals. The majority were diagnostic biopsies including 1780 liver parenchyma, 3400 focal liver lesions and 404 pancreatic lesions. 7525 interventions (92.1 %) were performed in hospitalized patients (mean age 62.6 years). Most operators were highly experienced in US-guided interventions (> 500 interventions prior to the study n = 5729; 70.1 %). Sedation was administered in 1131 patients (13.8 %). Needle diameter was ≥ 1 mm in 7162 punctures (87.9 %) with main focus on core needle biopsies (18 G, n = 4185). Clinically relevant bleeding complications with need of transfusion (0.4 %), surgical bleeding control (0.1 %) and radiological coiling (0.05 %) were very rare. Bleeding complications with fatal outcome occurred in four patients (0.05 %). The frequency of major bleeding complications was significantly higher in patients with an INR > 1.5 (p < 0.001) and patients taking a medication potentially interfering with platelet function or plasmatic coagulation (p < 0.0333).

CONCLUSION

This prospective multicentre study confirms the broad spectrum of percutaneous US-guided intraabdominal interventions. However diagnostic liver biopsies dominate with the use of core needle biopsies (18 G). Percutaneous US-guided interventions performed by experienced sonographers are associated with a low bleeding risk. Major bleeding complications are very rare. A pre-interventional INR < 1.5 and individual medication risk assessment are recommended.

Arxula adeninivorans recombinant adenine deaminase and its application in the production of food with low purine content

AIMS

Construction of a transgenic Arxula adeninivorans strain that produces a high concentration of adenine deaminase and investigation into the application of the enzyme in the production of food with low purine content.

METHODS AND RESULTS

The A. adeninivorans AADA gene, encoding adenine deaminase, was expressed in this yeast under the control of the strong inducible nitrite reductase promoter using the Xplor(®) 2 transformation/expression platform. The recombinant enzyme was biochemically characterized and was found to have a pH range of 5.5-7.5 and temperature range of 34-46 °C with medium thermostability. A beef broth was treated with the purified enzyme resulting in the concentration of adenine decreasing from 70.4 to 0.4 mg l(-1).

CONCLUSIONS

It was shown that the production of adenine deaminase by A. adeninivorans can be increased and that the recombinant adenine deaminase can be used to lower the adenine content in the food.

SIGNIFICANCE AND IMPACT OF THE STUDY

Adenine deaminase is one component of an enzymatic system that can reduce the production of uric acid from food constituents. This study gives details on the expression, characterization and application of the enzyme and thus provides evidence that supports the further development of the system.

Elicitation of the immune response to p-phenylenediamine in allergic patients: the role of dose and exposure time

BACKGROUND

Usage of hair dye products containing p-phenylenediamine (PPD) is a concern for PPD-allergic individuals.

OBJECTIVES

The present study investigates the role of dose and exposure time on elicitation of allergic contact dermatitis under conditions of permanent hair dyeing.

METHODS

Elicitation responses after application of a typical hair dye product containing 2% PPD for 30 min followed by rinsing were analysed in 38 PPD-allergic individuals with a documented history of hair dye-related allergy. Skin binding experiments in vitro were performed to distinguish the dose available for elicitation from the dose applied.

RESULTS

A positive reaction was elicited in 20 of 20 patients with grades ++ to +++ and 12 of 18 with grade + according to the classification of the International Contact Dermatitis Research Group. Under conditions of diagnostic patch testing (48 h exposure), the dose available for elicitation is more than 10-fold higher compared with the dose available for hair dyeing (30-min exposure, rinsing of product).

CONCLUSIONS

This investigation demonstrates that under simulated hair dye use conditions the actual exposure to PPD is more than an order of magnitude lower than under diagnostic patch testing, although sufficient to elicit a clearly noticeable reaction in 84% of PPD patch test-positive individuals.

Novel metabolic routes during the oxidation of hydroxylated aromatic acids by the yeast Arxula adeninivorans

AIM

To complete our study on tannin degradation via gallic acid by the biotechnologically interesting yeast Arxula adeninivorans as well as to characterize new degradation pathways of hydroxylated aromatic acids.

METHODS AND RESULTS

With glucose-grown cells of A. adeninivorans, transformation experiments with hydroxylated derivatives of benzoic acid were carried out. The 12 metabolites were analysed and identified by high performance liquid chromatography and GC/MS. The yeast is able to transform the derivatives by oxidative and nonoxidative decarboxylation as well as by methoxylation. The products of nonoxidative decarboxylation of protocatechuate and gallic acid are substrates for further ring fission.

CONCLUSION

Whereas other organisms use only one route of transformation, A. adeninivorans is able to carry out three different pathways (oxidative, nonoxidative decarboxylation and methoxylation) on one hydroxylated aromatic acid. The determination of the KM-values for protocatechuate and gallic acid in crude extracts of cells of A. adeninivorans cultivated with protocatechuate and gallic acid, respectively, suggests that the decarboxylation of protocatechuate and gallic acid may be catalysed by the same enzyme.

SIGNIFICANCE AND IMPACT OF THE STUDY

This transformation pathway of protocatechuate and gallic acid via nonoxidative decarboxylation up to ring fission is novel and has not been described so far. This is also the first report of nonoxidative decarboxylation of gallic acid by a eukaryotic micro-organism.

Yeast Phytases: Present Scenario and Future Perspectives

Phytases hydrolyze phytates to liberate soluble and thus readily utilizable inorganic phosphate. Although phytases are produced by various groups of microbes, yeasts being simple eukaryotes and mostly non-pathogenic with proven probiotic benefits can serve as ideal candidates for phytase research. The full potential of yeast phytases has not, however, been exploited. This review focuses attention on the present status of knowledge on the production, characterization, molecular characteristics, and cloning and over-expression of yeast phytases. Several potential applications of the yeast phytases in feeds and foods, and in the synthesis of lower myo-inositol phosphates are also discussed.

Contrast-enhanced ultrasound for the characterization of focal liver lesions--diagnostic accuracy in clinical practice (DEGUM multicenter trial)

PURPOSE

To evaluate the diagnostic benefit of contrast-enhanced ultrasound for the differential diagnosis of liver tumors in clinical practice.

MATERIALS AND METHODS

From May 2004 to December 2006 1349 patients (male 677, female 672) with a hepatic tumor lacking a definite diagnosis based on B-mode ultrasound and power Doppler ultrasound were examined at 14 hospitals by contrast-enhanced ultrasound using a standardized protocol (pulse/phase inversion imaging, mechanical index < 0.4). The Tumor status was assessed based on the vascularity pattern and contrast enhancement seen in focal lesions during the arterial, portal, and late phase. The diagnosis established after contrast-enhanced ultrasound was compared to histology (> 75% cases) or in some cases to CT or MRI.

RESULTS

The final diagnosis of hepatic tumors included 573 benign hepatic tumors (hemangiomas n = 242, focal nodular hyperplasia n = 170, hepatocellular adenoma n = 19, other benign lesions n = 142) and 755 malignant hepatic tumors (metastases n = 383, hepatocellular carcinoma n = 279, other malignant lesions n= 93). The overall diagnostic accuracy of contrast-enhanced ultrasound in comparison to the correct final diagnosis based on the combined gold standard was 90.3%. Contrast-enhanced ultrasound was able to correctly assess 723/755 malignant lesions (sensitivity 95.8%) and 476/573 benign lesions (specificity 83.1%). The positive predictive value of contrast-enhanced ultrasound for the diagnosis of a malignant tumor was 95.4% and the negative predictive value of contrast-enhanced ultrasound was 95.7%.

CONCLUSION

Contrast-enhanced ultrasound clearly improves the differential diagnosis of hepatic tumors and is very helpful in clinical practice when B-scan or power Doppler morphological criteria are missing.

Acid phosphatase production by recombinant Arxula adeninivorans

Acid phosphatase production by recombinant Arxula adeninivorans was carried out in submerged fermentation. Using the Plackett-Burman design, three fermentation variables (pH, sucrose concentration, and peptone concentration) were identified to significantly affect acid phosphatase and biomass production, and these were optimized using response surface methodology of central composite design. The highest enzyme yields were attained in the medium with 3.9% sucrose and 1.6% peptone at pH 3.8. Because of optimization, 3.86- and 4.19-fold enhancement in enzyme production was achieved in shake flasks (17,054 U g(-1) DYB) and laboratory fermenter (18,465 U g(-1) DYB), respectively.

Single daily dose of cyclosporine in patients with primary glomerulonephritis and nephrotic syndrome

AIMS

Single daily dose cyclosporine (SDD-CsA) might be a new option providing comparable efficacy, increased compliance and less nephrotoxicity compared to standard twice-daily dose cyclosporine (TDD-CsA). The aim of this trial was to prove the feasibility of SDD-CsA as primary and secondary maintenance therapy in patients with nephrotic syndrome.

METHODS

We treated 25 adult patients with nephrotic syndrome and chronic primary glomerulonephropathy with SDD-CsA for a period of 12 months or more. 12 patients were pre-treated with twice-daily dose cyclosporine (TDD-CsA) and were then switched secondarily to a single daily dose after a median period of 8 months (sSDD-CsA). 13 patients were treated primarily with single daily dose cyclosporine (pSDD-CsA).

RESULTS

In primary SDD-CsA patients, proteinuria decreased significantly from 9.2 - 0.8 g/l (p = 0.02) and serum protein increased significantly from 54 - 71 g/l (p = 0.03) during the study period. In secondary SDD-CsA patients, serum protein increased further (64 - 69, p = 0.04) after switching to SDD-CsA. In secondary SDD-CsA patients, the median total daily CsA dose was significantly lower (200 mg) with SDD-CsA compared to previous twice-daily dosing (300 mg, p = 0.01). Serum creatinine did not differ significantly before and after therapy and between the groups.

CONCLUSIONS

SDD-CsA is effective in patients with nephrotic syndrome as primary and secondary maintenance therapy. SDD-CsA allows for significantly lower total daily doses, probably with less nephrotoxicity.

Non-conventional yeasts as producers of polyhydroxyalkanoates?genetic engineering of Arxula adeninivorans

The non-conventional yeast Arxula adeninivorans was equipped with the genes phbA, phbB and phbC of the polyhydroxyalkanoate (PHA) biosynthetic pathway of Ralstonia eutropha, which encode beta-ketothiolase, NADPH-linked acetoacetyl-CoA reductase and PHA synthase, respectively. Arxula strains transformed solely with the PHA synthase gene (phbC) were able to produce PHA. However, the maximum content of the polymer detected in these strains was just 0.003% poly-3-hydroxybutyrate (PHB) and 0.112% poly-3-hydroxyvalerate (PHV). The expression of all three genes (phbA, phbB, phbC) resulted in small increases in the PHA content of the transgenic Arxula cells. However, under controlled cultivation conditions with minimal medium and ethanol as the carbon source, the recombinant yeast was able to accumulate up to 2.2% PHV and 0.019% PHB. Possible reasons for these differences are discussed.

The constitutive AHSB4 promoter--a novel component of the Arxula adeninivorans-based expression platform

An Arxula adeninivorans-AHSB4 gene, encoding histone H4, was isolated and characterized. The gene includes a coding sequence of 363 bp disrupted by a 51-bp intron, similar to the situation in other fungal H4 genes. The identity of the gene was confirmed by the high degree of homology of the derived amino acid sequence with that of other H4 histones. The gene is strongly and constitutively expressed, maintaining this expression profile under salt-stress conditions. The AHSB4 promoter was tested for suitability in heterologous gene expression using genes encoding the intracellular green fluorescent protein and the secreted human serum albumin (HSA) for assessment. Plasmids incorporating respective expression cassettes were used to transform the host strain A. adeninivorans LS3, which forms budding cells at 30 degrees C, and strain 135, which forms mycelia under these conditions. Transformants of both types were found to harbor a single copy of the heterologous DNA. Strong constitutive expression was observed during culture in salt-containing and salt-free media, as expected from the expression profile of AHSB4. In 200-ml shake-flask cultures, maximal HSA levels of 20 mg l(-1) culture medium were achieved. This productivity could be increased to 50 mg l(-1 )in strains harboring two copies of the expression cassette. The AHSB4 promoter thus provides an attractive component for constitutive heterologous gene expression under salt-free and salt-stress conditions.

IgG and IgE immune response against the surface glycoprotein gp200 of Saccharomyces cerevisiae in patients with atopic dermatitis

The heat-stable and soluble glycoprotein gp200 (molecular weight 200 kDa) is part of the cell wall of S. cerevisiae. Recently, an association was shown between IgA and IgG against gp200 and inflammation in Crohn's disease. Gp200 is able to induce a proliferation of human lymphocytes in vitro, together with a natural killer cell associated cytotoxicity. Specific IgE against Saccharomyces cerevisiae (baker's or brewer's yeast) may be detected in approximately 73%, against Candida albicans in 68% of those patients suffering from severe atopic dermatitis. The aim of this study was to elucidate the possible role of an anti-gp200 immune response for the pathogenesis of atopic dermatitis by immunoblot analysis. Anti-gp200 IgE was found in 55% of healthy individuals, in 67% of individuals with atopic predisposition without eczema, in 63% of the patients with mild atopic dermatitis, and in 86% of patients with severe atopic dermatitis, respectively. On the contrary, anti-gp200 IgG could be shown in 55% of healthy individuals, in 89% of individuals with atopic predisposition but without eczema, in 100% of patients with mild atopic dermatitis, and in 79% with severe atopic dermatitis, respectively. No immunoreactivity was found when an extract of Arxula adeninivorans was used as antigen. These results underline the specificity of the immunoblot results with gp200 from Saccharomyces cerevisiae. It can be concluded that occurrence of specific IgE against Saccharomyces cerevisiae cannot be explained by a cross reactivity, e.g., against Candida albicans allergens. Further investigations with the recombinant gp200 will give information on the role of this glycoprotein both in atopic dermatitis and Morbus Crohn.

Regulation of the AEFG1 gene, a mitochondrial elongation factor G from the dimorphic yeast Arxula adeninivorans LS3

Oxygen influences the synthesis of mitochondrial proteins by alteration of the expression of mitochondrial genes and several nuclear genes. One of the genes localised in the nucleus is the EFG1 gene that encodes the mitochondrial elongation factor G (MEF-G). This unique gene (AEFG1) has been isolated from the non-conventional dimorphic yeast, Arxula adeninivorans LS3. The AEFG1 gene comprises a ORF of 2,274 bp, which corresponds to 757 amino acids. In the present study, the regulation of AEFG1 has been analysed for different morphological stages of A. adeninivorans and various culture conditions. It was demonstrated that the transfer of aerobically growing cultures to anaerobic conditions resulted in an accumulation of AEFG1 transcript, correlating with an increase in AMEF-G protein concentration. Since this regulation occurred in budding-cell culture growing at 30 degrees C and in both of the mycelial cultures grown at 45 degrees C and 30 degrees C, respectively, it was the oxygen level (but not the cultivation temperature or the morphological stage) which influenced the AEFG1 regulation.

Genetic transformation and biotechnological application of the yeast Arxula adeninivorans

The relatively unknown, non-pathogenic, dimorphic, haploid, ascomycetous yeast Arxula adeninivorans exhibits some unusual properties which are of biotechnological interest. The yeast is able to assimilate and ferment many compounds as sole source of carbon and/or nitrogen, it utilises n-alkanes and degrades starch efficiently. A. adeninivorans features such as thermo- and haloresistance as well as the yeast's uncommon growth and secretion behaviour should be especially emphasised. In media containing up to 20% NaCl, A. adeninivorans is able to grow at cultivation temperatures up to 48 degrees C. Additionally, the dimorphism of the yeast is unusual. Arxula grows at up temperatures of up to 42 degrees C as budding cells, which turn into mycelia at higher temperatures. This environmentally conditioned dimorphism is reversible and budding is reestablished when the cultivation temperature is decreased below 42 degrees C. Alteration of morphology correlates with changes in secretion behaviour. Mycelium cultures accumulate two-fold higher protein concentrations and contain two- to five-fold higher glucoamylase and invertase activities in the medium than budding cells. Based on these unusual properties, Arxula adeninivorans is used for heterologous gene expression and as a gene donor to construct more suitable yeasts for biotechnology. For example the Arxula glucoamylase gene was successfully expressed in Saccharomyces cerevisiae and Kluyveromyces lactis. Both transformed yeasts are able to assimilate and ferment starch as carbon source. A transformation system is used for heterologous gene expression which is based on integration of linearised DNA fragments in two to ten copies, e.g. into the 25S rDNA of A. adeninivorans by homologous recombination. The obtained transformants are mitotically stable. The expression of the lacZ gene from E. coli as well as the XylE gene from Pseudomonas putida indicates the suitability of A. adeninivorans as host for heterologous gene expression.

Designing an amperometric thick-film microbial BOD sensor

Thick film oxygen electrodes manufactured by screen print method have been used as a transducer for a biochemical oxygen demand (BOD) sensor. The kinetics of the immobilized yeast, Arxula adeninivorans (Arxula) has been studied. The apparent KM of immobilized Arxula (> 100 microM) is higher than free cells of Arxula (70 microM). The increase in KM caused by the effect of immobilization extends the linear range of the sensor. End-point measurement and quasi-kinetic measurement have been studied comparatively as measurement procedures with a good correlation. The Vmax for end-point measurement is 790.7 microM/s and that for quasi-kinetic measurement is 537.3 microM/s. The limit of detection is calculated 1.24 mg/l BOD. Using the quasi-kinetic measurement, instead of end-point measurements, the measuring time can be reduced from 5-30 min to 100 s. The sensor layer thickness or increase in the layer of covering gel can increase the KM that is accompanied with the extension of the linear range of the sensor. Nevertheless, increase in the layer of covering gel will not increase the saturation signal. Domestic wastewater was checked by the thick film BOD sensor and the results are satisfactory.

HLA-A, B, Cw and DRB1, DRB3/4/5, DQB1, DPB1 frequencies in German immunoglobulin A-deficient individuals

HLA class I and II frequencies and haplotype frequencies were determined in 80 German immunoglobulin (Ig)A-deficient individuals and 157 healthy controls with normal IgA levels using serological and DNA typing methods. For several alleles, significant associations were found, which could be explained mainly in the context of a positive association with three different extended haplotypes (HLA-B*08:DRB1*0301: DQB1*0201, HLA-B*14:DRB1*0102:DQB1*0501 and HLA-B*44:DRB1*0701:DQB1*0202) and a negative association with a fourth haplotype (HLA-B*07:DRB1*1501:DQB1*0602). Furthermore, for the first time this study reports a positive association of IgA deficiency with DPB1 alleles. Homozygosity rate for the gene loci DRB1 and DQB1 was increased in IgA deficiency. Further analysis suggested a different pattern of HLA associations depending on the degree of IgA deficiency and the gender of the IgA-deficient individuals.

Amperometric measurement of copper ions with a deputy substrate using a novel Saccharomyces cerevisiae sensor

The first microbial biosensor to detect Cu2+ by an amperometric method has been developed. For this purpose, recombinant Saccharomyces cerevisiae strains are suitable as the microbial component. These strains contain plasmids with the Cu2+-inducible promoter of the CUP1-gene from Saccharomyces cerevisiae fused to the lacZ-gene from E. coli. On this sensor the CUP1 promoter is first induced by the Cu2+-containing probe and subsequently lactose is used as a deputy substrate to make the measurement. If Cu2+ is present in the sample, these recombinant strains are able to utilize lactose as a carbon source, which leads to alterations in the oxygen consumption of the cells. The sensor measured Cu2+ in a concentration range between 0.5 and 2 mM CuSO4. In addition, an indirect amperometric measurement principle was developed which allows the detection of samples containing Cu2+ and fast biodegradable substances.

Halotolerance of the yeast Arxula adeninivorans LS3

The non-pathogenic, dimorphic, ascomycetous yeast Arxula adeninivorans LS3 is halotolerant. It can grow in a minimal medium containing up to 20% NaCl. The growth parameters are only weakly influenced by 10% NaCl. However, NaCl in a concentration higher than 10% causes a decrease in the specific growth rate, a longer adaptation phase and a lower cell count in the stationary growth phase. Concentrations of glycerol and trehalose, which differed 100-fold in magnitude in a salt free medium, are also influenced differently by salt. NaCl induces accumulation of intracellular glycerol in exponentially growing cells but a reduced concentration of intracellular trehalose in stationary cells. Transcripts of the genes ARFC3, encoding a component of the replication factor C, and GAA, encoding a secretory glucoamylase, can be detected only in cells cultured in media with NaCl concentrations below 10%. Furthermore, NaCl in high concentration reduces the level of secreted proteins including glucoamylase end invertase.

Morphology-related effects on gene expression and protein accumulation of the yeast Arxula adeninivorans LS3

The dimorphism of the yeast Arxula adeninivorans LS3 is regulated by cultivation temperatures. Up to 42 degrees C the yeast grows as budding cells, which turn to mycelia at higher temperatures. To test whether the dimorphism is exclusively induced by high temperatures or also by other conditions, mutants were selected with an altered behaviour with respect to dimorphism. After mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine, five of 25,000 colonies formed a very rough surface consisting of mycelia at 30 degrees C, in contrast to the wild-type. These mutants allow temperature-mediated and morphology-related effects on gene expression and protein accumulation to be distinguished. Budding cells and mycelia showed different expression of genes encoding secretory proteins at the same temperature. Mycelia secreted two-fold more protein than budding cells, including the enzymes glucoamylase and invertase. This indicated that morphology, rather than temperature, is the decisive factor in the analysed processes.

Measurement of biodegradable substances using the salt-tolerant yeast Arxula adeninivorans for a microbial sensor immobilized with poly(carbamoyl)sulfonate (PCS). Part II: Application of the novel biosensor to real samples from coastal and island regions

A microbial sensor for rapid measurement of the amount of biodegradable substances based on the salt-tolerant yeast Arxula adeninivorans LS3 has been developed especially for coastal and island regions. Our parameter, the so-called sensorBOD, that is available after only a few minutes, agrees with the 5-day value for the biochemical oxygen demand (BOD5) very well. We have employed the Arxula sensor in the short-time estimation and supervision of the BOD of both domestic and industrial wastewater with high salinity. The novel sensor makes it possible to monitor the different types of wastewater rapidly without pretreatment, and it can be used for an active process control of sewage treatment works. Compared to a commercially available sensor, the novel sensor achieves better agreement between sensorBOD and BOD5 measurements with salt containing samples.

The green fluorescent protein targets secretory proteins to the yeast vacuole

The green fluorescent protein (GFP) was used as a marker to study the intracellular transport of vacuolar and secretory proteins in yeast. Therefore, the following gene constructs were expressed in Saccharomyces cerevisiae under control of the GAL1 promoter: GFP N-terminally fused to the yeast secretory invertase (INV-GFP), the plant vacuolar chitinase (CHN-GFP) and its secretory derivative (CHNDeltaVTP-GFP), which did not contain the vacuolar targeting peptide (VTP), both chitinase forms (CHN and CHNDeltaVTP), GFP without any targeting information and two secretory GFP variants with and without the VTP of chitinase (N-GFP-V and N-GFP). Whereas chitinase without VTP is accumulated in the culture medium the other gene products are retained inside the cell up to 48 h of induction. Independently of a known VTP they are transported to the vacuole, so far as they contain a signal peptide for entering the endoplasmic reticulum. This was demonstrated by confocal laser scanning microscopy, immunocytochemical analysis and subcellular fractionation experiments as well. The transport of the GFP fusion proteins is temporary delayed by a transient accumulation in electron-dense structures very likely derived from the ER, because they also contain the ER chaperone Kar2p/Bip. Our results demonstrate that GFP directs secretory proteins without VTP to the yeast vacuole, possibly by the recognition of an unknown vacuolar signal and demonstrates, therefore, a first limitation for the application of GFP as a marker for the secretory pathway in yeast.

Measurement of biodegradable substances using the salt-tolerant yeast Arxula adeninivorans for a microbial sensor immobilized with poly(carbamoyl) sulfonate (PCS) Part I: Construction and characterization of the microbial sensor

A microbial biosensor based on the yeast Arxula adeninivorans LS3 has been developed for measurement of biodegradable substances. Arxula is immobilized in the hydrogel poly(carbamoyl) sulfonate (PCS). The immobilized yeast membrane is placed in front of an oxygen electrode with -600 mV versus Ag/AgCl. Arxula is salt tolerant; it can give a stable signal up to 2.5 M NaCl in sample (120 mM in measuring cell). The sensor's measurements are highly correlated to BOD5 measurements. It has a very high stability which can last for 40 day without any decrease in signal. The linear range of the sensor is up to a corresponding BOD value of 550 mg/l.

Molecular cloning and expression of the ARFC3 gene, a component of the replication factor C from the salt-tolerant, dimorphic yeast Arxula adeninivorans LS3

The yeast replication factor C (RF-C) is a multi-polypeptide complex with five sub-units involved in chromosomal DNA replication. This factor, encoded by five genes, is well characterized for the yeast Saccharomyces cerevisiae. However, RF-C components from other yeast species have not been analysed yet. Here we report the cloning and characterization of ARFC3 from the dimorphic and osmo-tolerant yeast Arxula adeninivorans. This gene encodes one subunit of the RF-C complex. It is localized on chromosome 1 of the four Arxula chromosomes and comprises a coding region of 1014 bp, which corresponds to 338 amino acids. Two introns are contained within this gene. The ARFC3 transcript level is influenced by both salt and temperature. The latter also influences the morphological state (budding cells, mycelium). High salt concentration and high temperature result in a rapid decrease of the ARFC3 mRNA.

The peptide HDEF as a new retention signal is necessary and sufficient to direct proteins to the endoplasmic reticulum

The key feature of tomato RNase LX localised solely outside the vacuole is the C-terminal peptide HDEF which is very similar to known endoplasmic reticulum (ER) retention signals. For functional testing of the ER-targeting ability of HDEF, different constructs including the complete RNase LX, two truncated forms without HDEF and the truncated chitinase FB7-1deltaVTP C-terminally flanked by HDEF, were expressed in Saccharomyces cerevisiae. The majority of RNase and chitinase, both containing HDEF, accumulates within the ER. However, the truncated constructs without the peptide are released into the medium. We provide compelling evidence that peptide HDEF at the C-terminus of secretory plant proteins is a new ER retention signal in yeast and most likely in plants.

AILV1 gene from the yeast Arxula adeninivorans LS3--a new selective transformation marker

The ILV1 gene of the yeast Arxula adeninivorans LS3 (AILV1) has been cloned from a genomic library, characterized and used as an auxotrophic selection marker for transformation of plasmids into this yeast. One copy of the gene is present in the Arxula genome, comprising 1653 bp and encoding 550 amino acids of the threonine deaminase. The protein sequence is similar (60.55%) to that of the threonine deaminase from Saccharomyces cerevisiae encoded by the gene ILV1. The protein is enzymatically active during the whole period of cultivation, up to 70 h. Maximal activities, as well as protein concentrations of this enzyme, were achieved after cultivation times of 20-36 h. The AILV1 gene is a suitable auxotrophic selection marker in transformation experiments using an Arxula adeninivorans ilv1 mutant and a plasmid containing this gene, which is fused into the 25S rDNA of Arxula adeninivorans. One to three copies of the linearized plasmid were integrated into the 25S rDNA by homologous recombination. Transformants resulting from complementation of the ilv1 mutation can be easily and reproducibly selected and in addition are mitotically stable. Therefore, the described system is preferred to the conventional selection for hygromycin B resistance.

Evidence for secretion of vacuolar alpha-mannosidase, class I chitinase, and class I beta-1,3-glucanase in suspension cultures of tobacco cells

We have investigated the possibility that vacuolar proteins can be secreted into the medium of cultured cells of Nicotiana tabacum L. Time-course and balance-sheet experiments showed that a large fraction, up to ca. 19%, of vacuolar alpha-mannosidase (EC 3.2.1.24) and vacuolar class I chitinase (EC 3.2.1.14) in suspension cultures accumulated in the medium within one week after subculturing. This effect was most pronounced in media containing 2,4-dichlorophenoxyacetic acid (2,4-D). Under comparable conditions only a small fraction, 1.8-5.1% of the total protein and ca. 1% of malate dehydrogenase (EC 1.1.1.37), which is localized primarily in the mitochondria and cytoplasm, accumulated in the medium. Pulse-chase experiments showed that newly synthesized vacuolar class I isoforms of chitinase and beta-1,3-glucanase (EC 3.2.1.39) were released into the medium. Post-translational processing, but not the release of these proteins, was delayed by the secretion inhibitor brefeldin A. Only forms of the proteins present in the vacuole, i.e. mature chitinase and pro-beta-1,3-glucanase and mature beta-1,3-glucanase, were chased into the medium of tobacco cell-suspension cultures. Our results provide strong evidence that vacuolar alpha-mannosidase, chitinase and beta-1,3-glucanase can be secreted into the medium. They also suggest that secretion of chitinase and beta-1,3-glucanase might be via a novel pathway in which the proteins pass through the vacuolar compartment.

Humoral immune response to a 200-kDa glycoprotein antigen of Saccharomyces cerevisiae is common in man

According to Heelan et al. patients suffering from Crohn's disease (CD) produce antibodies against a cell wall associated glycoprotein antigen gp200 of the yeast Saccharomyces cerevisiae, while healthy people do not. Here the authors show, that antibodies against this glycoprotein gp200 can also be detected in the sera of healthy humans. The intensity of the antibody titer which is measured by immunoblot experiments is independent from the state of health. The Saccharomyces cerevisiae specific gp200 is a highly glycosylated protein localized not only in the cell wall but also accumulated in the culture medium. Some of the tested sera from CD patients, as well as from healthy adults, also reacted with a 120-kDa glycoprotein which is to be found in preparations containing secreted proteins. Because the binding of antibodies is greatly reduced by periodate treatment of gp200 and by the 120-kDa polypeptide, it is very likely that their carbohydrate moieties are the antigenic determinants against which the specific human antibodies are directed. The human humoral immune response applies only to Saccharomyces cerevisiae antigens, because no analogous immune responses could be detected against antigens derived from the yeast Arxula adeninivorans.

Correct targeting of a vacuolar tobacco chitinase in Saccharomyces cerevisiae--post-translational modifications are dependent on the host strain

The chitinase gene FB7-1 of Nicotiana tabacum cv. samsun line 5 was expressed in the two Saccharomyces cerevisiae strains, INVSC2 and H4, under the control of the GAL1 promoter from S. cerevisiae and a multicopy plasmid vector. Both yeast strains express the plant gene as enzymatic active proteins. In transformants of the strain INVSC2, 94% of the total plant chitinase is contained inside the cells, probably within the vacuole which has been confirmed by subcellular fractionation as well as immunohistochemical experiments. This retention inside the cells is due to the C-terminally located 7 amino acids long vacuolar targeting peptide of the prochitinase. When this sequence was removed, chitinase was transported into the culture medium. Pulse-chase experiments revealed that during translation in transformants of both yeast strains one chitinase polypeptide can be immunoadsorbed with specific antibodies. In the case of INVSC2-transformants, newly formed chitinase is modified in a 60 min chase to slightly increase its molecular mass, whereas in H4-transformants the molecular mass constantly remained 32 kDa. By Western blot analysis two chitinase corresponding polypeptides of 32 and 37 kDa were accumulated in the culture medium of both transformants carrying the chitinase gene without the vacuolar targeting sequence. The larger one was very likely O-glycosylated. Whereas, both polypepitdes were also detected in cell extracts of the H4-transformant, only the smaller one was found in the INVSC2-transformant. The plant chitinase passed through the endoplasmic reticulum on its way to the vacuole. The N-terminal signal peptide responsible for the uptake into the endoplasmic reticulum is cleaved correctly. However, cleavage of the vacuolar targeting peptide located at the C-terminus, to give the mature chitinase is obviously influenced by the genetic background of the host strain. In INVSC2-transformants chitinase accumulates in its mature form whereas both the polypeptides of H4-transformants retain their vacuolar targeting peptide. Our results demonstrate that in the case of plant class I chitinase, the plant sorting signal is recognized in yeast cells but post-translational modifications are influenced by the host strain.

Integrative transformation of the dimorphic yeast arxula adeninivorans LS3 based on hygromycin B resistance

A transformation system has been developed for the dimorphic yeast Arxula adeninivorans based on a stable integration of the donor DNA into ribosomal DNA. For this purpose a cassette was constructed which contains the E. coli hph gene, conferring hygromycin B resistance, fused to the 5' expression signals of the A. adeninivorans TEF1 gene, encoding the translation elongation factor EF-1alpha, and the transcription termination region of the Saccharomyces cerevisiae PHO5 gene. This cassette was fused into the 25S rDNA of A. adeninivorans. Linearization of this vector was required for high transformation frequencies. The vector was integrated in multiple copies into the 25S rDNA by homologous recombination. Copy number was not altered even after the growth of transformants for 15 generations under non-selective growth conditions. Microscopical analyses revealed that integration of the transformed plasmid did not influence the dimorphism, which is triggered at 42 degrees C for both transformed and non-transformed cells.

Rapid physiological characterization of microorganisms by biosensor technique

Eleven microorganisms, Arxula adeninivorans LS3, Candida boidinii DSM 70034, Candida lactis-condensi DSM 70635, Pichia jadinii DSM 2361, Pichia minuta DSM 7018, Kluyveromyces lactis DSM 4394, Pseudomonas putida DSM 50026, Alcaligenes sp. DSM 30002, Arthrobacter nicotianae DSM 20123 as well as Issatchenkia orientalis DSM 70077 and Rhodococcus erythropolis DSM 311 were characterized by the sensor technique by injection of 30 different substrates and substrate mixtures. The obtained data which are based on the determination of respiratory rate of microorganisms are similar to physiological characteristics obtained with conventional methods. In comparison to these conventional methods the sensor technique works much more rapid and permits quantification of the data. Therefore, the described technique provides an alternative method for the characterization of microorganisms.

Physiological characterization of a microbial sensor containing the yeast Arxula adeninivorans LS3

The yeast Arxula adeninivorans LS3 is a suitable organism for use as part of a microbial sensor. In combination with an amperometric oxygen electrode the sensor offered a possibility for the physiological characterization of this yeast. About 300-400 measurements could be carried out with a single Arxula sensor. The microbial sensor was remarkably stable for over 35 days, when kept at 37 degrees C during the operation time and at room temperature overnight. The physiological characteristics of Arxula adeninivorans LS3 obtained with the sensor technique were identical to the data obtained with the conventional techniques. However, the sensor technique makes it additionally possible to quantify the physiological data. So the substrates ribose, citric acid, glycerol, oil and benzoate produced signals lower than 10% in comparison to the glucose signal. Fructose, xylose, sucrose, maltose, gentianose, glucosamine, glutamic acid, tryptophan, butyric acid, lauryl acid and propionic acid reached 10-70%, galactose, alanine, glycine, lysine and methionine signals were similar to the glucose signal whereas acetic acid, ethyl alcohol, capron acid, capryl acid and caproic acid reached the highest signals up to 434%.

A set of genetic markers for the chromosomes of the imperfect yeast Arxula adeninivorans

The nuclear genome of the anamorphic yeast Arxula adeninivorans was analysed by benomyl-induced haploidization of parasexual hybrids marked with 32 auxotrophic mutations and pulsed field gel electrophoresis followed by DNA hybridization. Twenty-seven genes have been arranged into four linkage groups by haploidization, 15 genes belong to group 1, six to group 2, and three each to groups 3 and 4. Five genes could be localized by DNA hybridization on three out of four separated chromosomes. The gene LYS2 of the largest linkage group 1 and the 25S rDNA were identified on the largest chromosome, the GAA and the TEF1 gene on chromosome 2, and the ILV1 gene of linkage group 4 on the smallest chromosome.

Identification of a group-I intron within the 25S rDNA from the yeast Arxula adeninivorans

The 25S rDNA of the yeast Arxula adeninivorans LS3 has been closed from a genomic library and sequenced. This DNA could be localized on chromosome 1 from A. adeninivorans and comprised 3790 bp. The DNA sequence from this rDNA of the strain LS3 is very similar to the 25S rDNA of Candida albicans (91.7%), Saccharomyces cerevisiae (90.5%), Schizosaccharomyces pombe (83.8%) and Mucor racemosus (79.2%). Additionally a 411 bp insertion could be localized within the 25S rDNA. This intervening sequence, which is devoid of any long open reading frame, is a group-IC intron as revealed from its site of insertion, predicted secondary structure, and its self-splicing capability. The Arxula intron is intermediate in structure and sequence between the ribosomal introns of Tetrahymena thermophila and C. albicans.

Long-term effects of restrictive culture conditions on Saccharomyces cerevisiae sec7 cells

Long-term effects of restrictive conditions on the temperature-sensitive S. cerevisiae sec7 mutant were studied. By microscopic analysis no cell lysis could be detected of cells cultured for up to 19 days at 37 degrees C. The optical density as well as the cell number remained constant during the whole period under restrictive conditions. However, restrictive conditions decreased the incorporation of 35S-methionine into intracellular proteins in a reversible manner indicating that protein biosynthesis was inhibited whereas the cells remained alive. Northern blot experiments revealed that restrictive conditions did not markedly decrease the ratio of the mRNA levels to total RNA for the genes TEF1, TEF2, SUC2, and BGL2 up to 73 hours. However the content of total RNA decreased drastically with increasing incubation times at restrictive temperature. In spite of the reduced total RNA content, cells are capable of new synthesis of mRNA under restrictive conditions which was shown by incubation of the cells in the presence of actinomycin D--an inhibitor of the mRNA synthesis. Most of the cells which survived a long-term incubation at 37 degrees C are not able to divide and to form colonies immediately after their transfer to permissive conditions.

Expression of the Arxula adeninivorans glucoamylase gene in Kluyveromyces lactis

The glucoamylase gene of the yeast Arxula adeninivorans was expressed in Kluyveromyces lactis by using the GAP promoter from Saccharomyces cerevisiae and a multicopy plasmid vector. The transformants secreted 90.1% of the synthesized glucoamylase into the culture medium. The secreted glucoamylase activities are about 20 times higher in comparison to those of Saccharomyces cerevisiae transformants using the same promoter. Secreted glucoamylase possesses identical N-terminal amino acid sequences to those secreted by A. adeninivorans showing that cleavage of the N-terminal signal peptide takes place at the same site. Biochemical characteristics of glucoamylase expressed by K. lactis and A. adeninivorans are very similar.

Slow-speed freezing of chemically unfixed biological tissues and long-term storage of frozen samples for cryoscanning electron microscopy

We describe a procedure in which plant tissue as well as a yeast culture on agar are frozen with slow cooling rates for observation of surface structures in a cryoscanning electron microscope. A system is also presented for long-term storage of frozen specimens under liquid nitrogen, in which the material is maintained for direct observation. Some small tools are described, which are essential for making preparations using slow-speed freezing and for the storage of prepared samples. Three examples of preparations with different complications are given: the "sculptures" on the surface of a leaf of Allium schoenoprasum, an early stage of flower development of Allium cernuum, and a part of an agar-grown colony of Arxula adeninivorans. In our experience, it is possible to store fully hydrated samples under the described conditions for more than a year without damaging the fine structures.

Temperature-dependent dimorphism of the yeast Arxula adeninivorans Ls3

Arxula adeninivorans Ls3 is described as an ascomycetous, arthroconidial, anamorphic, xerotolerant yeast, which was selected from wood hydrolysates in Siberia. By using minimal salt medium or yeast-extract-peptone-medium with glucose or maltose as carbon source it was shown that this yeast is able to grow at up to 48 degrees C. Increasing temperatures induce changes in morphology from the yeast phase to mycelia depending on an altered programme of gene expression. This dimorphism is an environmentally conditioned (reversible) event and the mycelia can be induced at a cultivation temperature of 45 degrees C. Depending on the morphology of strain Ls3 (yeast phase or mycelia) the secretion behaviour as well as the spectrum of polypeptides accumulated in the culture medium changed. The activities of the accumulated extracellular enzymes glucoamylase and invertase were 2 to 3 times higher in cultures grown at 45 degrees C than in those grown at 30 degrees C. While the level of the glucoamylase protein secreted from mycelia between 45 and 70 hours did not change, biochemical activity decreased after a cultivation time of 43 hours. It was shown that this effect depended on both the catabolic repression of the glucoamylase by glucose and the thermal inactivation of this enzyme in media without or with low concentrations of starch or maltose.

Cloning and characterization of a TEF gene for elongation factor 1 alpha from the yeast Arxula adeninivorans

The translation elongation factor EF-1 alpha appears to play a major role in the control of cell proliferation and ageing in higher eukaryotes. Here we report the cloning of the TEF1 gene encoding the elongation factor 1 alpha of the dimorphic yeast Arxula adeninivorans Ls3. The gene is localized on chromosome 2 from Arxula adeninivorans, comprises 1380 bp and encodes a protein containing 459 amino acids. In contrast to other fungi, a second TEF gene encoding an identical, or nearly identical, polypeptide could not be identified. The transcriptional activity of the TEF1 gene did not change during mycelial growth, whereas a slight decrease could be detected during the yeast growth.

Comparative biochemical, genetical and immunological studies of glucoamylase producing Arxula adeninivorans yeast strains

Seven Arxula adeninivorans strains originating from The Netherlands (CSIR 1136, CSIR 1138 and CBS 8244T), South Africa (CSIR 1147, CSIR 1148 and CSIR 1149) and Siberia (Ls3) were compared concerning their secretory glucoamylase. Within the spectrum of secretory polypeptides obtained by SDS-polyacrylamide gel electrophoresis, the glucoamylase corresponding polypeptide, could be identified by means of specific antibodies directed against the glucoamylase of strain Ls3. The molecular masses of the glucoamylases vary from 84 to 95 kDa. After endoglycosidase F treatment of the secretory proteins, the N-linked carbohydrate content for each glucoamylase could be quantified at about 25%. Glucoamylase activity staining of secretory proteins separated under nondenaturing conditions revealed one glucoamylase active protein for the Dutch strains and two active forms for the strains originating from South Africa and Siberia. Highest activities of glucoamylase can be measured at the end of the exponential growth phase for each strain. The Dutch strain CSIR 1138 secretes the highest activity. Optimum values for temperature and pH were determined and compared. By means of pulsed field gel electrophoresis and Southern analysis, the glucoamylase corresponding gene could be localized on the second of the four chromosomes of each yeast strain.

[HLA and selective IgA deficiency]

A selective deficiency of IgA is developed significantly (p < 0.05) more frequently by HLA-A2-negative than by HLA-A2-positive healthy persons. The frequent combination of A1/A3 is absent. The incidence of HLA-B8-positive persons is increased (p < 0.01). A selective disadvantage is discussed.