Structural Similarities, in Relation with the Cross-Reactivity, of Hymenoptera Allergenic Dipeptidyl Peptidases IV-An Overall Comparison Including a New Dipeptidyl Peptidase IV Sequence from Vespa velutina

(1) Background: Dipeptidyl Peptidases IV (DPPIVs), present in many organisms, are minor components in the venoms of Hymenoptera, where they have been identified as cross-reactive allergenic molecules. Considering that the structure of homologous DPPIVs is well characterized, we aimed to explain which regions have higher similarity among these proteins and present a comparison among them, including a new Vespa velutina DPPIV sequence. Moreover, two cases of sensitization to DPPIVs in wasp- and honeybee-sensitized patients are presented. (2) Methods: Proteomic analyses have been performed on the venom of the Asian hornet Vespa velutina to demonstrate the sequence of its DPPIV (allergen named Vesp v 3, with sequence accession number P0DRB8, and with the proteomic data available via ProteomeXchange with the identifier PXD046030). A comparison performed through their alignments and analysis of the three-dimensional structure showed a region with higher similarity among Hymenoptera DPPIVs. Additionally, ImmunoCAP™ determinations (including specific inhibition experiments), as well as IgE immunoblotting, are performed to demonstrate the allergenicity of Api m 5 and Ves v 3. (3) Results and Conclusions: The data presented demonstrate that the similarities among Hymenoptera DPPIVs are most likely localized at the C-terminal region of these enzymes. In addition, a higher similarity of the Vespa/Vespula DPPIVs is shown. The clinical cases analyzed demonstrated the allergenicity of Api m 5 and Ves v 3 in the sera of the allergic patients, as well as the presence of this minor component in the preparations used in venom immunotherapy.

Supplementation with inulin-type fructans affects gut microbiota and attenuates some of the cardiometabolic benefits of a plant-based diet in individuals with overweight or obesity

Background

The gut microbiota has emerged as a potential therapeutic target to improve the management of obesity and its comorbidities.

Objective

We investigated the impact of a high fiber (∼38 g/d) plant-based diet, consumed ad libitum, with or without added inulin-type fructans (ITF), on the gut microbiota composition and cardiometabolic outcomes in subjects with obesity. We also tested if baseline Prevotella/Bacteroides (P/B) ratio predicts weight loss outcomes.

Methods

This is a secondary exploratory analysis from the PREVENTOMICS study, in which 100 subjects (82 completers) aged 18-65 years with body mass index 27-40 kg/m2 were randomized to 10 weeks of double-blinded treatment with a personalized or a generic plant-based diet. Changes from baseline to end-of-trial in gut microbiota composition (16S rRNA gene amplicon sequencing), body composition, cardiometabolic health and inflammatory markers were evaluated in the whole cohort (n = 82), and also compared in the subgroup of subjects who were supplemented with an additional 20 g/d ITF-prebiotics (n = 21) or their controls (n = 22).

Results

In response to the plant-based diet, all subjects lost weight (-3.2 [95% CI -3.9, -2.5] kg) and experienced significant improvements in body composition and cardiometabolic health indices. Addition of ITF to the plant-based diet reduced microbial diversity (Shannon index) and selectively increased Bifidobacterium and Faecalibacterium (q < 0.05). The change in the latter was significantly associated with higher values of insulin and HOMA-IR and lower HDL cholesterol. In addition, the LDL:HDL ratio and the concentrations of IL-10, MCP-1 and TNFα were significantly elevated in the ITF-subgroup. There was no relationship between baseline P/B ratio and changes in body weight (r = -0.07, p = 0.53).

Conclusion

A plant-based diet consumed ad libitum modestly decreases body weight and has multiple health benefits in individuals with obesity. Addition of ITF-prebiotics on top this naturally fiber-rich background selectively changes gut microbiota composition and attenuates some of the realized cardiometabolic benefits.

Clinical trial registration

[https://clinicaltrials.gov/ct2/show/NCT04590989], identifier [NCT04590989].

Diverse and highly cross-reactive T-cell responses in ragweed allergic patients independent of geographical region

BACKGROUND

Ragweed frequently causes seasonal allergies in North America and Europe. In the United States, several related ragweed species with diverse geographical distribution cause allergic symptoms. Cross-reactivity towards related ragweed species of IgE and treatment-induced IgG₄ has been demonstrated previously. However, less is known about the underlying T-cell cross-reactivity.

METHODS

The allergen content of ragweed extracts was determined by mass spectrometry and related to T-cell epitopes of Amb a allergens (group 1, 3, 4, 5, 8 and 11) in 20 American ragweed allergic patients determined by FluoroSpot and proliferation assays. T-cell responses to 50 frequently recognized Amb a-derived T-cell epitopes and homologous peptides from western ragweed (Amb p), giant ragweed (Amb t) and mugwort (Art v) were investigated in an additional 11 American and 14 Slovakian ragweed allergic donors.

RESULTS

Ragweed extracts contained all known allergens and isoallergens thereof. Donor T-cell responses were diverse and directed against all Amb a 1 isoallergens and to most minor allergens investigated. Similar response patterns were seen in American and Slovakia donors. Several epitopes were cross-reactive between isoallergens and ragweed species, some even including mugwort. T-cell cross-reactivity generally correlated with allergen sequence homology.

CONCLUSION

T-cell epitopes of multiple allergens/isoallergens are involved in the diverse T-cell responses in ragweed allergic individuals. T-cell lines were highly cross-reactive to epitopes of related ragweed species without any apparent geographical response bias. These data support that different ragweed species can be considered an allergen homology group with Amb a as the representative species regarding diagnosis as well as allergy immunotherapy.

Immunoproteomic analysis of house dust mite antigens reveals distinct classes of dominant T cell antigens according to function and serological reactivity

BACKGROUND

House dust mite (HDM) allergens are a common cause of allergy and allergic asthma. A comprehensive analysis of proteins targeted by T cells, which are implicated in the development and regulation of allergic disease independent of their antibody reactivity, is still lacking.

OBJECTIVE

To comprehensively analyse the HDM-derived protein targets of T cell responses in HDM-allergic individuals, and investigate their correlation with IgE/IgG responses and protein function.

METHODS

Proteomic analysis (liquid chromatography-tandem mass spectrometry) of HDM extracts identified 90 distinct protein clusters, corresponding to 29 known allergens and 61 novel proteins. Peripheral blood mononuclear cells (PBMC) from 20 HDM-allergic individuals were stimulated with HDM extracts and assayed with a set of ~2500 peptides derived from these 90 protein clusters and predicted to bind the most common HLA class II types. 2D immunoblots were made in parallel to elucidate IgE and IgG reactivity, and putative function analyses were performed in silico according to Gene Ontology annotations.

RESULTS

Analysis of T cell reactivity revealed a large number of T cell epitopes. Overall response magnitude and frequency was comparable for known and novel proteins, with 15 antigens (nine of which were novel) dominating the total T cell response. Most of the known allergens that were dominant at the T cell level were also IgE reactive, as expected, while few novel dominant T cell antigens were IgE reactive. Among known allergens, hydrolase activity and detectable IgE/IgG reactivity are strongly correlated, while no protein function correlates with immunogenicity of novel proteins. A total of 106 epitopes accounted for half of the total T cell response, underlining the heterogeneity of T cell responses to HDM allergens.

CONCLUSIONS AND CLINICAL RELEVANCE

Herein, we define the T cell targets for both known allergens and novel proteins, which may inform future diagnostics and immunotherapeutics for allergy to HDM.

Short ragweeds is highly cross-reactive with other ragweeds

BACKGROUND

The most widespread ragweed (Ambrosia) species in North America are short ragweed (Ambrosia artemisiifolia; Amb a), giant ragweed (Ambrosia trifida; Amb t), and western ragweed (Ambrosia psilostachya; Amb p). Varied geographic distributions of ragweed species raise questions regarding the need for ragweed species-specific allergen immunotherapy.

OBJECTIVE

To determine allergenic cross-reactivity among ragweed species by immunologic analyses of sera from subjects allergic to ragweed from North America and Europe.

METHODS

Sera were collected from 452 subjects allergic to ragweed who participated in Amb a sublingual immunotherapy tablet clinical trials. All subjects had positive skin prick test and serum IgE against Amb a. Ragweed-specific IgE (pre treatment) and IgG4 (post treatment) were measured by ImmunoCAP. IgE inhibition studies among Amb a, Amb t, and Amb p were conducted. Using pooled sera from another ragweed-allergic population, IgE inhibition studies of 7 less widespread Ambrosia species also were conducted.

RESULTS

A strong correlation between Amb a vs Amb p and Amb t serum IgE levels was observed. In the vast majority of pretreatment sera, Amb a inhibited Amb a, Amb p, and Amb t IgE reactivity by more than 90%. Strong correlations were observed between Amb a vs Amb p and Amb t post-treatment IgG4 levels. In pooled sera, Amb a extract inhibited the binding of serum IgE to all 10 ragweed species by 98%-100%.

CONCLUSION

In a population of subjects allergic to Amb a, substantial allergenic cross-reactivity among Amb a, Amb p, and Amb t was demonstrated. These in vitro data suggest that an Amb a-based single-species ragweed allergen immunotherapy may be therapeutically active in patients exposed to diverse ragweed pollens.

TRIAL REGISTRY

Clinicaltrials.gov, NCT00770315, NCT00783198, and NCT00330083.

Effect of mutations on the thermostability of Aspergillus aculeatus β-1,4-galactanase

New variants of β-1,4-galactanase from the mesophilic organism Aspergillus aculeatus were designed using the structure of β-1,4-galactanase from the thermophile organism Myceliophthora thermophila as a template. Some of the variants were generated using PROPKA 3.0, a validated pKa prediction tool, to test its usefulness as an enzyme design tool. The PROPKA designed variants were D182N and S185D/Q188T, G104D/A156R. Variants Y295F and G306A were designed by a consensus approach, as a complementary and validated design method. D58N was a stabilizing mutation predicted by both methods. The predictions were experimentally validated by measurements of the melting temperature (Tm ) by differential scanning calorimetry. We found that the Tm is elevated by 1.1 °C for G306A, slightly increased (in the range of 0.34 to 0.65 °C) for D182N, D58N, Y295F and unchanged or decreased for S185D/Q188T and G104D/A156R. The Tm changes were in the range predicted by PROPKA. Given the experimental errors, only the D58N and G306A show significant increase in thermodynamic stability. Given the practical importance of kinetic stability, the kinetics of the irreversible enzyme inactivation process were also investigated for the wild-type and three variants and found to be biphasic. The half-lives of thermal inactivation were approximately doubled in G306A, unchanged for D182N and, disappointingly, a lot lower for D58N. In conclusion, this study tests a new method for estimating Tm changes for mutants, adds to the available data on the effect of substitutions on protein thermostability and identifies an interesting thermostabilizing mutation, which may be beneficial also in other galactanases.

S100A8/A9 deficiency in nonhealing venous leg ulcers uncovered by multiplexed antibody microarray profiling

BACKGROUND

Knowledge on the underlying mechanisms for nonhealing chronic wounds is fragmentary.

OBJECTIVES

To increase our understanding of the pathogenesis, the relationship between healing ability and a large panel of proteins was studied using a specially designed wound-healing antibody-based microarray.

METHODS

Wound fluid from nondiabetic patients with nonhealing venous leg ulcers was compared with that from patients with healing open granulating acute wounds. The high-throughput method enabled simultaneous measurement of the relative levels of 48 different proteins representing major categories of wound-healing modulators.

RESULTS

Unexpectedly, several of the examined proteins, including various proinflammatory cytokines, proteinases and antiproteinases, were not significantly (P>0·001) changed in chronic wound fluid. For example, levels of matrix metalloproteinase-9 and one of its substrates type IV collagen were similar in the two groups. The wound fluid samples displayed similar degrees of fragmentation of fibronectin by Western blot analysis and the total fibronectin levels were doubled (P<0·001) in chronic compared with acute wounds. The increased fibronectin originated from α-smooth muscle actin-positive myofibroblasts and not from the circulation. S100A8/A9 was the sole protein that was reduced (P<0·001) in wound fluid from venous ulcers [median 226 μg mL(-1) (interquartile range 213-278)] compared with healing wounds [455 μg mL(-1) (382-504)], probably reflecting a difference in inflammatory cell composition.

CONCLUSION

The molecular anomalies in chronic wounds are more subtle than the current paradigm and neither excessive proteinase activity nor deficiencies of examined extracellular matrix proteins, growth factors or angiogenic/angiostatic factors appear to contribute significantly to the nonhealing state of venous leg ulcers.

Immunohistochemical staining for thyroid peroxidase (TPO) of needle core biopsies in the diagnosis of scintigraphically cold thyroid nodules

BACKGROUND

Cold thyroid nodules are common, in particular in iodine-deficient areas, but only a minority of them are malignant requiring surgery. Thyroid peroxidase (TPO) immunostaining of fine-needle aspiration cytology (FNAC) material has proven helpful in diagnosing cells from malignant lesions, but the procedure has its limitations in a routine setting.

PURPOSE

To improve diagnosis and reduce surgery rate, the FNAC procedure was replaced by needle core biopsy (NCB), which was routinely stained for TPO by the monoclonal antibody mAb 47.

MATERIALS AND METHODS

During a 5-year period 427 consecutive patients with a cold thyroid nodule were evaluated by ultrasound-guided NCB, which had been routinely stained for TPO in an automated immunostainer. Sensitivity and specificity and predictive values of the TPO immunostaining were estimated, based on the final diagnosis obtained from surgical resection.

RESULTS

The majority of nodules with benign NCB diagnosis were not surgically removed, and thus a subgroup of 140 operated nodules formed the basis for the calculations. Sensitivity and specificity for benign and malignant lesions were 100% if the oxyphilic variant of adenomas and minimally invasive follicular carcinomas were excluded. By inclusion of these, the values fell to 89% and 97%, respectively. The predictive value of a positive test was 96% and the predictive value of a negative test was 97%.

CONCLUSION

TPO immunostaining was found to be a valuable adjunct to morphology in the diagnosis of cold thyroid nodules of the nonoxyphilic type.

Reduced mortality for women with mammography-detected breast cancer in east Denmark and south Sweden

The 5-year relative survival from breast cancer in Denmark is 10 percentage points lower than in Sweden. This difference has been demonstrated previously as being caused partly by more involved lymph nodes and larger tumours in Denmark. Sweden has had nationwide mammography-screening coverage since 1991, whereas this is still in its infancy in Denmark. In the search for an explanation for the remaining survival difference, patient delay was a likely candidate. This study compared patient delay and mammography-detection between two national regions. Data on patient delay and mammography were obtained from hospital records from 1989 and 1994, and analysed using Cox proportional hazard analysis of death within the first 5 years, with the factors age, country, delay/mammography detection and established patho-anatomic variables. A comparison of patient delay and mammography detection in 1989 and 1994 showed more mammography-detected tumours in south Sweden and more women with long delay in east Denmark. Mammography detection, but not long patient delay, had a significant effect on the death hazard when adjusting for patho-anatomic risk factors. The hazard ratio was not eliminated in 1989, but in 1994, the hazard ratio between east Denmark and south Sweden was reduced from 1.3 to 1.1. In conclusion, patient delay did not appear to have any effect on 5-year survival when adjusting for patho-anatomic factors, but tumour detection by mammography affected survival favourably and partly explained the survival difference between east Denmark and south Sweden.

Can the survival difference between breast cancer patients in Denmark and Sweden 1989 and 1994 be explained by patho-anatomical variables?—A population-based study

Analyses of data from cancer registries have shown a 10% unit difference in 5-year relative survival between Danish and Swedish patients with breast cancer. This study investigates the effect of age and patho-anatomic variables on this survival difference. Hospital records were collected for women over 40 years of age diagnosed in 1989 or 1994 in east Denmark and south Sweden; patho-anatomical variables and survival were compared between 2289 Danish and 1715 Swedish women. Tumours were smaller, node-negative axillae more frequent and well-differentiated tumours almost 10% more frequent in Sweden. A superior 5-year relative survival in Sweden was found in the 50- to 79-year age group. The adjusted hazard rate ratio between countries was 1.7 in 1989 and 1.3 in 1994. Conditional survival after surviving the first 5 years was similar for the two countries. Adjusting for patho-anatomical variables reduced but did not eliminate the higher risk of death among the Danish patients. Higher population death rates could explain some but not all of the residual elevated risk for Danish women.

Dependence of morphology on agitation intensity in fed-batch cultures of Aspergillus oryzae and its implications for recombinant protein production

We previously reported that, although agitation conditions strongly affected mycelial morphology, such changes did not lead to different levels of recombinant protein production in chemostat cultures of Aspergillus oryzae (Amanullah et al., 1999). To extend this finding to another set of operating conditions, fed-batch fermentations of A. oryzae were conducted at biomass concentrations up to 34 g dry cell weight/L and three agitation speeds (525, 675, and 825 rpm) to give specific power inputs between 1 and 5 kWm(-3). Gas blending was used to control the dissolved oxygen level at 50% of air saturation except at the lowest speed where it fell below 40% after 60-65 h. The effects of agitation intensity on growth, mycelial morphology, hyphal tip activity, and recombinant protein (amyloglucosidase) production in fed-batch cultures were investigated. In the batch phase of the fermentations, biomass concentration, and AMG secretion increased with increasing agitation intensity. If in a run, dissolved oxygen fell below approximately 40% because of inadequate oxygen transfer associated with enhanced viscosity, AMG production ceased. As with the chemostat cultures, even though mycelial morphology was significantly affected by changes in agitation intensity, enzyme titers (AGU/L) under conditions of substrate limited growth and controlled dissolved oxygen of >50% did not follow these changes. Although the measurement of active tips within mycelial clumps was not considered, a dependency of the specific AMG productivity (AGU/g biomass/h) on the percentage of extending tips was found, suggesting that protein secretion may be a bottle-neck in this strain during fed-batch fermentations.

[TPO immunostaining of the solitary, cold thyroid nodules]

INTRODUCTION

The chance of malignancy in scintigraphically cold thyroid nodules is 2-24%. Differentiation between malignant and benign cytology is difficult. The aim of this study was to evaluate the ability of immunostaining (MoAB47--raised against thyroid peroxidase (TPO)) to differentiate between malignant and benign cells taken from cold thyroid nodules by fine needle aspiration biopsy (FNAB) in order to reduce the number of unnecessary thyroid operations.

MATERIALS AND METHODS

One hundred and eighty-one patients (150 female) with a scintigraphically cold, solitary thyroid nodule were entered between 1993 and 1996. Fifty-seven were excluded for various reasons. Material removed by FNAB was stained with MoAB47 and routine staining. Staining of 80% or more of the cells was considered benign, less than 80% was considered malignant. Routine staining of operatively removed material was used as the final diagnosis.

RESULTS

A pattern with negative TPO staining was found in all lesions that were subsequently proved to be malignant. In all but one, the lesions subsequently diagnosed as being benign stained positive for TPO. The sensitivity and specificity were respectively 1.0 and 0.99.

CONCLUSION

TPO immunostaining of material removed by FNAB is a powerful tool in the differentiation between benign and malignant tumours.

[Untreated breast cancer in Denmark 1978-1995]

INTRODUCTION

The lack of registration of women who have received no or alternative treatment for breast cancer has been criticised. No distinction is made in the Danish Cancer Register between these patients and those who only receive palliative treatment for other reasons, such as old age, advanced disease, and competing illnesses. We have estimated the number of women in this group of patients, who, in reality, had not received any treatment with the intent to cure under the health care system, and whether a meaningful analysis of survival for these patients is feasible.

METHOD

All women with breast cancer diagnosed during the years 1978-1995 were extracted from the Cancer Register, and we isolated those who had been registered as having had no or only palliative treatment and who had survived for a minimum of 45 days after diagnosis. A search was made in the Danish Breast Cancer Co-operative Group register for unreported treatment and the residual group was followed up individually.

RESULTS

Out of 49.058 women with histologically or cytologically verified breast cancer, the Cancer Register listed 840 women with no registered treatment of their disease. Of these, there were 103 cases of carcinoma in situ. A match with the DBCG register revealed that 188 women had nevertheless been operated on. Among the remaining 549 women, 99 were truly untreated, and for 77 of these the reasons given were another or advanced disease or old age. Only 22 women had initially declined treatment for no specific reason. Five of these had later decided on subsequent curative treatment, which leaves 17 women in the category "breast cancer untreated at her own request" ("untreated breast cancer at own will"). Nine are dead, five had their tumour excised at biopsy, and the remaining three are alive with tumours diagnosed by fine needle aspiration biopsy (1) or thru-cut biopsy (2) after 7.7 and 4 years, respectively.

CONCLUSION

This report has shown that a survival analysis based on the Cancer Register of untreated breast cancer in relation to treated breast cancer is not meaningful. A true estimation of survival after untreated versus treated breast cancer can only be achieved through a randomised study, which would be unethical.

Task-specific enhancement of short-term, but not long-term, memory by class I metabotropic glutamate receptor antagonist 1-aminoindan-1,5-dicarboxylic acid in rats

Pharmacological application of broad agonists and antagonists has supported the notion of a potential role of metabotropic glutamate receptors (mGluRs) in learning and memory formation, but the specific function of the different classes or individual subtypes remains elusive. Furthermore, our knowledge with respect to different learning mechanisms is still fragmentary. In an attempt to clarify further the function of mGluRs in learning, rats were trained in various paradigms in the presence/absence of the specific class I antagonist 1-aminoindan-1,5-dicarboxylic acid (AIDA). Intraperitoneal application of AIDA prior to training led to enhanced within-session performance in animals trained in a positively reinforced reference memory task in a three-choice maze. However, this enhancement did not result in increased retention as measured by the number of correct responses during the first four trials of each session on subsequent days. The increase was purely an enhancement in within-session performance, required doses higher than 2 mg/kg, and was not accompanied by an unspecific increase in activity as monitored in the open field. By contrast, AIDA animals trained in a combined shock-reinforced contextual and cue conditioning paradigm demonstrated a pronounced retention deficit compared with controls in conditioning to the context, but not the cue (a high-frequency tone). Although within-session performance during context and cue periods was slightly increased in the AIDA group, the difference did not reach significance. Drug-induced hyperactivity, which could account for the memory deficit, was excluded by recordings of activity in specific activity cages. These results shed new light on the possible function of class I mGluRs in learning and memory formation and imply that systemic blockade of class I mGluRs may enhance short-term memory under certain learning conditions.

The class I metabotropic glutamate receptor antagonist, AIDA, improves short-term and impairs long-term memory in a spatial task for rats

Effects of the class I selective metabotropic glutamate receptor antagonist, 1-aminoindan-1,5-dicarboxylic acid (AIDA), on spatial procedural learning and episodic short-term memory of rats were investigated in an appetitively reinforced 3-choice delayed match-to-position task. First, an acute intraperitoneal injection of AIDA (2 mg/kg) was given 20 min before a single training session of 20 trials using repeated reward position in one alcove out of three. AIDA caused facilitated short-term acquisition within such a session compared to saline treated controls. Secondly, injections were given before each of ten sessions (48 h intervals) also using constant reward position. The results showed AIDA induced inhibition of procedural between-session acquisition. Finally, the use of reward positions in a non-repetitive but trial-specific version of the 3-choice test revealed a facilitating effect of AIDA on episodic short-term memory.

[Preoperative scintigraphic localization of hyperfunctioning parathyroid glands]

Preoperative identification of hyperfunctioning parathyroid glands was performed by 99m-Tc-sestamibi scintigrams in 29 patients with hyperparathyroidism. Out of 30 histopathologically proven diseased parathyroid glands 21 were identified by scintigraphy. The diagnostic specificity (PVpos) was 88%. All diseased glands weighing more than 1200 mg were identified by scintigraphy including four glands in the mediastinum. 99m-Tc-sestamibi scintigraphy can identify the larger hyperfunctioning parathyroid glands with high reliability. The method was of great value in situations with ectopic abnormal parathyroid glands.

Growth energetics and metabolic fluxes in continuous cultures of Penicillium chrysogenum

Continuous cultures of the penicillin producing fungus Penicillium chrysogenum have been analyzed with respect to the macromolecular composition of the mycelium. All cultivations were carried out using a chemically defined medium with glucose as the growth limiting component. Biomass was harvested at steady state and analyzed for proteins, lipids, RNA, DNA, and carbohydrates. Carbohydrates present in the cell wall, i.e., glucans and chitin, and carbohydrates serving as storage materials, i.e., glycogen, were measured. It was observed that the levels of DNA and lipids are relative constant, whereas the proteins and stable RNA levels increase with the specific growth rate and the total amount of carbohydrates decreases with the specific growth rate. Glycogen is only present in small amounts, decreasing with the specific growth rate. As an average the measured macromolecules account for 77 +/- 2% (w/w) of the biomass. On the basis of estimations of the metabolic costs for biosynthesis and polymerization of the different macromolecules the total ATP and NADPH requirements for cell biosynthesis from glucose and inorganic salts, i.e., YxATP,growth and YxNADPH, have been quantified. The biosynthesis of 1 g biomass was calculated to require 39.9 mmol of ATP and 7.5 mmol of NADPH when cytosolic acetyl-CoA is formed from citrate by citrate lyase and oxaloacetate is recycled back into the TCA cycle. Other pathways of acetyl-CoA biosynthesis have been considered. The calculations show that the different biosynthetic routes for generating cytosolic acetyl-CoA have a significant influence on the theoretical value of ATP and NADPH requirements for cell biosynthesis. Combining a detailed stoichiometric model for growth and product formation of P. chrysogenum with experimental data on the macromolecular composition of P. chrysogenum and precise measurements of substrate uptake and product formation the intracellular flux distribution was calculated for different cultivation conditions.

[Mammographic screening in the municipality of Copenhagen. Results of the first screening round]

The aim of the study was to evaluate the results from the prevalence round of the mammography screening programme in the Municipality of Copenhagen. All women who by 1 April 1991 were 50-69 years old, and who lived in the Municipality of Copenhagen, were during the period 1 April 1991-24 April 1993 offered a mammography. Those with suspect findings were recalled for further examination and possible biopsy. Women with breast cancer were offered treatment according to the standard national protocols (DBCCG). The participation rate was 71% (30,416/43,087). Among these 2043 (6.7%) were re-examined and 592 (1.9%) underwent surgical biopsy. Breast cancer was revealed in 359 (1.2%) women, of whom 88% had an invasive breast cancer. Prevalence of breast cancer increased significantly with increasing age. The positive predictive value for breast cancer among those re-examined was 18% and for those who had a surgical biopsy 61%. Among women with an invasive breast cancer 41% had a tumour of 10 mm or less, 80% had negative lymph node status and 56% had breast conserving surgery. During the following 12 months 14 women with a normal mammogram at the screening round developed breast cancer giving a sensitivity of 96%. It is concluded that the first mammography screening in Denmark showed the highest breast cancer prevalence published so far. A possible explanation could be a high sensitivity of the screening method, indicated by a relatively high frequency of small cancers. The screening programme was fully comparable with international standards.

Continuous cultivation of Penicillium chrysogenum. Growth on glucose and penicillin production

A series of constant-mass, continuous cultivations of the penicillin producing mold Penicillium chrysogenum was carried out using a chemically defined medium with glucose as the growth-limiting component. The stoichiometry for growth of P. chrysogenum on glucose was characterized in terms of mass-yield and maintenance coefficients. Saturation kinetics with respect to glucose was used to describe the glucose consumption rate at steady-state conditions. Transient data indicate that the maximum rate of glucose consumption at a particular set of operating conditions is correlated to the metabolic 'capacity' of the mold as reflected by its intracellular RNA content. A progressive loss in the penicillin productivity in glucose limited chemostat cultures was correlated to the formation of two mutants. The two mutants were characterized by their sporulation when grown as surface cultures and by Southern dot-tests for delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS), isopenicillin-N synthase (IPNS) and acyl-CoA:6-APA acyltransferase (AT). The loss of penicillin productivity was caused by an increasing fraction of mutants which had lost the genes encoding for all three enzymes needed in the penicillin synthesizing pathway.

[Silicone breast implants]

A brief review of the use of silicone breast implants, their structure, methods of implantation and complications is presented. Acute complications are rare, being mainly infection and hematoma. Long-term complications, on the contrary, are common, consisting mainly of capsular contracture around the prosthesis with subsequent pain and deformation of the breast. More rarely silicone granulomas form, and prosthesis rupture or herniation occurs. The importance of silicone leakage for these complications is discussed separately as well as the treatment of and prevention of capsular contracture and demonstration of silicone in tissue. A critical attitude towards the use of silicone breast implants, when these are used for purely cosmetic purposes, is recommended at present. New improved types of silicone breast implants are currently being tested clinically.