Is short-course radiotherapy and total neoadjuvant therapy the new standard of care in locally advanced rectal cancer? A sensitivity analysis of the RAPIDO clinical trial

BACKGROUND

The results of the RAPIDO trial have been accepted as evidence in favour of short-course radiotherapy (SC-RT) followed by chemotherapy before total mesorectal excision in high-risk locally advanced rectal cancer. A noteworthy concern is that the RAPIDO trial did not ensure that all patients in the control arm received adjuvant chemotherapy. This may bias statistical estimates in favour of the experimental arm if adjuvant chemotherapy is active in rectal cancer. Moreover, the 5-year update revealed an increase in the risk of local relapse in the experimental arm.

MATERIALS AND METHODS

We carried out sensitivity analyses to determine how plausible effects of adjuvant chemotherapy, adjusted by the proportion of patients in the standard arm receiving adjuvant treatment, would have influenced the observed treatment effect estimate of the RAPIDO trial. The most plausible values for the benefit of adjuvant chemotherapy were determined by Bayesian re-analysis of a prior meta-analysis.

RESULTS

The meta-analysis suggested that oxaliplatin/fluorouracil-based adjuvant chemotherapy may improve disease-free survival (DFS) in rectal cancer although the signal is weak [hazard ratio (HR) 0.84, 95% credible interval, 0.57-1.15]; probability of benefit (HR <1) was 91.2%. In the sensitivity analysis, the HR for disease-related treatment failure would remain <1, thus favouring total neoadjuvant therapy (TNT), on most occasions, but the null hypothesis would not have been rejected in various credible settings. For the RAPIDO data to be consistent with the null effect, a moderate benefit of adjuvant chemotherapy (HR for DFS between 0.75 and 0.80) and 70%-80% of exposed participants would suffice.

CONCLUSION

The decision to make adjuvant chemotherapy optional in the standard arm may have biased the results in favour of the experimental arm, in a scenario in which TNT does not offset the increase in local recurrences after SC-RT.

Strategies to develop radiomics and machine learning models for lung cancer stage and histology prediction using small data samples

Predictive models based on radiomics and machine-learning (ML) need large and annotated datasets for training, often difficult to collect. We designed an operative pipeline for model training to exploit data already available to the scientific community. The aim of this work was to explore the capability of radiomic features in predicting tumor histology and stage in patients with non-small cell lung cancer (NSCLC). We analyzed the radiotherapy planning thoracic CT scans of a proprietary sample of 47 subjects (L-RT) and integrated this dataset with a publicly available set of 130 patients from the MAASTRO NSCLC collection (Lung1). We implemented intra- and inter-sample cross-validation strategies (CV) for evaluating the ML predictive model performances with not so large datasets. We carried out two classification tasks: histology classification (3 classes) and overall stage classification (two classes: stage I and II). In the first task, the best performance was obtained by a Random Forest classifier, once the analysis has been restricted to stage I and II tumors of the Lung1 and L-RT merged dataset (AUC = 0.72 ± 0.11). For the overall stage classification, the best results were obtained when training on Lung1 and testing of L-RT dataset (AUC = 0.72 ± 0.04 for Random Forest and AUC = 0.84 ± 0.03 for linear-kernel Support Vector Machine). According to the classification task to be accomplished and to the heterogeneity of the available dataset(s), different CV strategies have to be explored and compared to make a robust assessment of the potential of a predictive model based on radiomics and ML.

Moderate hypofractionated helical tomotherapy for prostate cancer in a cohort of older patients: a mono-institutional report of toxicity and clinical outcomes

PURPOSE OR OBJECTIVE

To evaluate toxicity and outcomes of moderately hypofractionated helical tomotherapy for the curative treatment of a cohort of patients aged ≥ 75 years with localized prostate cancer (PC).

MATERIALS AND METHODS

From January 2013 to February 2017, 95 patients with median age 77 years (range 75-88) were treated for PC. 39% were low risk, 33% intermediate risk (IR), 28% high risk (HR). Median iPSA was 9.42 ng/ml (1.6-107). Androgen deprivation was prescribed according to NCCN recommendations. All patients received 70 Gy in 28 fractions to the prostate; 61.6 Gy were delivered to the seminal vesicles for IR; whole pelvis irradiation with a total dose of 50.4 Gy was added in the HR group. Toxicity evaluation was based on CTCAE V4.0 criteria, biochemical failure was defined following Phoenix criteria. Quality of Life was assessed with the EPIC-26 index. Overall survival and biochemical failure-free survival were analysed with Kaplan-Meier method.

RESULTS

With a median follow-up of 36 months (range 24-73), acute and late toxicity were acceptable. No correlation between toxicity patterns and clinical or dosimetric parameter was registered. EPIC-26 showed a negligible difference in urinary and bowel function post-treatment that did not reach statistical significance. The 2- and 3-years OS were 93% and 87% with cancer specific survival of 97.9% and 96.2%.

CONCLUSION

Moderate hypofractionated RT reported excellent outcomes in our cohort of older patients. Shorter schedules may be proposed regardless of chronological age facilitating the treatment compliance in the older population.

18F-FDG PET/CT in the Staging and Management of Breast Cancer: Value in Disease Outcome and Planning Therapy

In hormone receptor-positive locally advanced breast cancer, endocrine therapy becomes an integral part of the therapeutic strategy. There are now significant numbers of available hormonal directed compounds, including selective aromatase and mTOR inhibitors, which allow an important therapeutic advance in these patients. Sequential F-FDG PET/CT studies provided essential information regarding response to different treatments, including targeted therapies, and adverse therapeutic effects that helped to better define the right moment to implement each therapeutic approach.

Baseline metabolic disturbances and the twenty-five years risk of incident cancer in a Mediterranean population

BACKGROUND AND AIMS

Obesity is predictive of metabolic syndrome (metS), type 2 diabetes, cardiovascular (CV) disease and cancer. The aim of the study is to assess the risk of incident cancer connected to obesity and metS in a Mediterranean population characterized by a high prevalence of obesity.

METHODS AND RESULTS

As many as 1133 subjects were enrolled in two phases and followed for 25 years (859 subjects) or 11 years (274 subjects) and incident cancer was registered in the follow-up period. Anthropometric measures and biochemical parameters were filed at baseline and evaluated as predictors of incident cancer by measuring hazards ratios (HR) using multivariate Cox parametric hazards models. Best predictive threshold for metabolic parameters and metS criteria were recalculated by ROC analysis. Fasting Blood Glucose >5.19 mmol/L [HR = 1.58 (1.0-2.4)] and the TG/HDL ratio (log₁₀) (Males > 0.225, Females > 0.272) [HR = 2.44 (1.3-4.4)] resulted independent predictors of survival free of cancer with a clear additive effect together with age classes [45-65 years, HR = 2.47 (1.3-4.4), 65-75 years HR = 3.80 (2.0-7.1)] and male gender [HR = 2.07 (2.3-3.1)].

CONCLUSIONS

Metabolic disturbances are predictive of cancer in a 25 years follow-up of a Mediterranean population following a traditional Mediterranean diet. The high prevalence of obesity and metS and the observed underlying condition of insulin resistance expose this population to an increased risk of cardiovascular disease and cancer despite the healthy nutritional habits.

[Body weight- independent variations in HDL-cholesterol following gastric bypass]

BACKGROUND

Bariatric surgery has multiple beneficial effects on lipid profile in patients with morbid obesity. However, these changes can be attenuated by weight regain. This retrospective study was designed to assess the effects of gastric bypass(GBP) on different lipid fractions over a 6 year follow-up.

PATIENTS AND METHODS

We studied 177 patients (135 women)with morbid obesity (BMI 44.2+0.4 kg/m2) aged 42.4+0.9 years before and 3, 6, 9, 12, 24, 36, 48, 60 and 72 months after laparoscopic proximal GBP. Anthropometry, body composition measurement (Bod-Pod) and fasting blood samples were taken in all evaluations to measure total cholesterol (TC),LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglycerides(TG), glucose and insulin.

RESULTS

GPB was followed by a significant BMI reduction (nadir BMI at 18 m 28.3+0.4 kg/m2 p<0,001) and fat mass decrease(p<0,001). Maximal percentage of excess BMI lost was 84.1%and that of body fat was 87% 18 months after GBP. These numbers decreased to 65.6% and 38.3% (p<0,005 vs nadir) respectively 72 months after the operation, indicating both weight and fat mass regain. TG and LDL-C values decreased 30% with respect to preoperative levels, while HDL-C increased 97%over initial values. This HDL-C increase was progressive even over the weight regain phase. Both TC/HDL-C and TG/HDL-Cratios normalized after GBP and values were sustained over the weight regain period until the end of the study.

CONCLUSIONS

These results confirm the beneficial effects of GBP on all lipid fractions, which are maintained over 6 years of follow-up. Globally, the rise in HDL-C seems to be independent of weight or fat mass changes, since it increases even over the weight regain phase, so contributing to a reduction in the prevalence of dyslipidaemia and to cardiovascular risk reduction.

Bronchoscopy in sarcoidosis: union is strength

Sarcoidosis is a benign disease of unknown etiology that is characterized by the formation of noncaseating epithelioid cell granulomas. Although a multisystemic disease, it primarily affects the lung and the lymphatic system of the body. When a histological diagnosis is required, bronchoscopy is frequently employed because allows tissue sampling from several anatomic sources, such as airways, lung parenchyma and hilar/mediastinal nodes. Transbronchial lung biopsies (TBLB), endobronchial biopsies (EBB) and conventional transbronchial needle aspiration (cTBNA) have long been the only bronchoscopic techniques to diagnose sarcoid granulomas, until the advent of endobronchial ultrasound guided needle aspiration (EBUS-TBNA). This technique shows excellent yield in sampling mediastinal adenopathies with a higher sensitivity than the conventional technique in sarcoidosis as well. Furthermore, non controlled studies, demonstrated its diagnostic superiority than EBB and TBLB in stages I (hilar adenopathies only) and II (hilar lymph nodes and parenchymal infiltrations) thoracic sarcoidosis. In a recent study, Gupta et al., randomized 130 patients with suspected stage I and II disease to undergo EBUS-TBNA or cTBNA in conjunction with transbronchial and endobronchial biopsies. The Authors demonstrated that the yield of cTBNA added to EBB and TBLB is similar to EBUS-TBNA plus transbronchial biopsies, although ultrasound guided transbronchial needle aspiration shows the best single diagnostic efficacy. In this review article we aimed to discuss the findings by Gupta in the context of medical literature, highlighting the importance of adding nodal aspirations (with or without ultrasound guidance) with bronchial and transbronchial samples to gain the optimal sensitivity in obtaining histological confirmation. We finally pointed out the need for future studies to evaluate the potential role of rapid on-site evaluation (ROSE) of needle aspirates in reducing additional sampling and related costs and complications.

Morbidity, mortality, and pathological response in patients with gastric cancer preoperatively treated with chemotherapy or chemoradiotherapy

BACKGROUND

Significant tumor downstaging has been achieved in patients with localized gastric adenocarcinoma by preoperative chemoradiotherapy (ChRT) or induction chemotherapy (Ch). However the influence of ChRT and Ch on postoperative outcomes has not yet been clarified, with very few studies examining this issue. We retrospectively analyzed the efficacy in terms of pathological response and early postoperative complications of two protocols of preoperative ChRT and Ch for locally advanced gastric cancer.

METHODS

Between 2000 and 2008, 72 patients with operable locally advanced gastric cancer (cT3-4/N+) were treated with preoperative treatment: 1-patients receiving induction Ch or 2-neoadjuvant Ch followed by concurrent ChRT. Postoperative histopathological regression and surgical complications were investigated including variables related to patients, surgical variables, preoperative treatment, and tumor.

RESULTS

There were no differences in the incidence of complications between the ChRT and Ch groups (30.9% vs. 33.3%). The most frequent complications were nonspecific surgical complications (pneumonia [12.5%] and infection from intravenous catheters [9.7%]). Risk factors for complications were high-body mass index (BMI > 25 kg/m(2) ) and extension of surgery to the pancreas and spleen. A major pathological response was observed in 33.3% of patients, being more frequent in the ChRT group (47.6% vs. 13.3%; χ(2) , P = 0.0024).

CONCLUSIONS

Preoperative treatment with Ch or ChRT for locally advanced gastric cancer can be performed safely with an acceptable operative morbidity and low operative mortality rate with careful consideration of the added risk associated with BMI and surgical resection of the pancreas and spleen. Ch and ChRT is feasible and effective in terms of pathological response and R0 resection.

Obesity and the metabolic syndrome in a student cohort from Southern Italy

BACKGROUND AND AIM

Cardiovascular (CV) risk factors present in childhood predict future CV events. Few data regarding the metabolic syndrome (MS) prevalence are available in adolescents from Mediterranean areas where obesity is becoming a social emergency. This study presents data of MS prevalence in a student cohort from southern Italy.

METHODS AND RESULTS

1629 students between 7 and 14 years of age underwent anthropometric measurements and a blood sample was obtained to assess biochemical parameters. MS risk factors were calculated based on age and gender adjusted percentiles of parameter distributions. MS prevalence rate was 0.022 using paediatric, age-adjusted criteria; the rate increased to 0.029 using a 90th percentile criteria for fasting blood glucose instead of >100mg/dL. Using the criteria issued by the International Diabetes Federation the MS prevalence rate dropped to 0.005. The exploratory factor analysis identified four factors: age/fat related, lipids, blood pressure and blood glucose. Family history of type 2 diabetes mellitus was associated with triglyceride [OR=1.55 (1.0-2.3)] and BMI [OR=1.71 (1.2-2.4)] but not to blood glucose by logistic regression analysis.

CONCLUSIONS

In a student cohort from Southern Italy, obesity is associated with the features of MS.

Telithromycin in lower respiratory tract infections

Telithromycin is a ketolide, a semisynthetic derivative of the 14-membered ring macrolide antibiotics, with an expanded spectrum of activity relative to macrolides. Its good tissue pharmacokinetic characteristics allows once-daily administration, and it has been successfully employed in lower respiratory tract infections. Recent data indicate that telithromycin may exert anti-inflammatory/immunomodulatory effects that may be of use in the treatment of both acute and chronic airway diseases. This review examines the role of telithromycin in lower respiratory tract infections, analyzing published data on exacerbations of chronic bronchitis, community-acquired pneumonia and asthma in adults. In addition, pharmacokinetic and pharmacodynamic properties of the drug are considered.

Small bowel evisceration after laparoscopic cholecystectomy: report of an unusual case

With the rapid development of laparoscopic surgery particularly in cholecystectomy, despite its own advantages, an ever increasing number of reports describe the appearance of new pathologies, due to laparoscopic approach. Evisceration is a rare complication previously described in gynecological obstetric procedures and only once in laparoscopic cholecystectomy. The case of a small bowel evisceration after laparoscopic cholecystectomy in a patient with a multifactorial etiology is presented: weakness area in the umbilical region, intractable cough in the first postoperative day and disruptive tear of the fascia to remove 2 large-size stones. The conclusion is drawn that, according to the literature, holes greater than 5 mm in diameter should be closed at fascial level and we believe that the removal of the gallbladder from epigastric holes is important, in order to avoid an enlargement and rupture of the umbilical port.

RT-PCR determination of maspin and mammaglobin B in peripheral blood of healthy donors and breast cancer patients

BACKGROUND

The aim of the present study was to evaluate the accuracy of two markers, maspin and mammaglobin B, singly or in combination, to detect breast cancer. To define better the potential and limits of the two markers for diagnostic purposes, blood positivity was analyzed in relation to clinical, pathological and biological tumor characteristics.

PATIENTS AND METHODS

The markers were determined in peripheral blood (PB) samples from 27 healthy donors and 140 previously untreated patients using nested reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Positivity for maspin in blood samples was observed in 24% of patients with an 89% specificity. For mammaglobin B, positivity was observed in 7% of patients and never in healthy donors. The presence of maspin was correlated with cell proliferation of the primary tumor (P = 0.015), whereas mammaglobin B positivity correlated with pathological stage (P = 0.013). The presence of either marker was significantly related to nodal status.

CONCLUSIONS

Our results indicate that the two markers in association could represent a potentially useful non-invasive tool to detect breast cancer. The validation of these markers as indicators of high risk of relapse is ongoing in a series of patients with an adequate follow-up.

A novel mutation of the extracellular matrix protein 1 gene (ECM1) in a patient with lipoid proteinosis (Urbach-Wiethe disease) from Sicily

BACKGROUND

Lipoid proteinosis (LP), also known as Urbach-Wiethe disease, is a rare autosomal recessive disorder characterized by a hoarse voice, warty skin infiltration and scarring. Mutations within the extracellular matrix protein 1 (ECM1) gene cause LP.

OBJECTIVES

We report the molecular analysis of the ECM1 gene in a Sicilian patient with LP in order to extend the mutation spectrum of this genodermatosis.

METHODS

We studied a 32-year-old female born from consanguineous parents who was diagnosed at the age of 11 years as having LP. She has a clinical phenotype corresponding to Urbach-Wiethe disease characterized by papules/nodules, indurated plaques and sometimes ulcerated lesions primarily involving the skin and mucous membranes, and extracutaneous features such as epilepsy, hoarseness of the voice and neuropsychiatric abnormalities. Samples of clinically affected skin obtained by biopsies were analysed after staining with haematoxylin and eosin, periodic acid-Schiff (PAS), and PAS-diastase. The whole ECM1 gene was analysed by direct sequencing.

RESULTS

We identified a homozygous nonsense mutation in exon 6 of the ECM1 gene, C589T (Q197Ter).

CONCLUSIONS

Over 60% of mutations occur in exons 6 and 7. Exon 7 is alternatively spliced and frameshift mutations in exon 7 lead to ablation of the ECM1a transcript, but not the shorter ECM1b transcript that normally lacks this exon. Homozygous nonsense or frameshift mutations in exon 6 are predicted to affect both full-length ECM1a and ECM1b transcripts, whereas ECM1b should be unaffected for similar types of mutation in exon 7. It has been suggested that individuals with mutations in exon 7 have a slightly milder phenotype than those with exon 6 mutations. This is the first report with respect to a novel mutation of the ECM1 gene responsible for recessive LP in Sicily.

Stress plays a role in the association between cognitive constructs and measures of eating disorders in male subjects

OBJECTIVE

Several theorists have hypothesized that stressful situations may trigger abnormal eating and even eating disorders in predisposed people. The purpose of this study was to assess whether a stressful situation would reveal an association between perfectionism and low self-esteem, and measures of eating disorder symptoms in male high school students.

METHOD

A sample of 61 male high school students completed the Eating Disorder Inventory, the Multidimensional Perfectionism Scale, and the Self Liking and Competence Scale three times: on an average school day, on the day of an exam and on the day the subjects received the results of that exam. Linear regression analysis was carried out to verify whether the dimensions of perfectionism were associated with the measures of eating disorders.

RESULTS

Interoceptive awareness was associated with 'Bulimia' only during the stressful situation and with 'Drive for thinness' both in stress and non stress situations. Other results were contradictory and difficult to interpret.

DISCUSSION

The results suggest that in nonclinical male individuals stress might bring out a previously absent association between some psychological predisposing factors for eating disorders and an actual desire or plan for ED related thoughts and behaviours. Such a finding suggests that stress may stimulate behaviours related to eating disorders in a predisposed personality. A central role may be played by interoceptive awareness in male subjects.

Prostaglandin E(2) inhibits fibroblast chemotaxis

Fibroblasts are the major source of extracellular connective tissue matrix, and the recruitment, accumulation, and stimulation of these cells are thought to play important roles in both normal healing and the development of fibrosis. Prostaglandin E(2) (PGE(2)) can inhibit this process by blocking fibroblast proliferation and collagen production. The aim of this study was to investigate the inhibitory effect of PGE(2) on human plasma fibronectin (hFN)- and bovine bronchial epithelial cell-conditioned medium (BBEC-CM)-induced chemotaxis of human fetal lung fibroblasts (HFL1). Using the Boyden blind well chamber technique, PGE(2) (10(-7) M) inhibited chemotaxis to hFN 40.8 +/- 5.3% (P < 0.05) and to BBEC-CM 49.7 +/- 11.7% (P < 0.05). Checkerboard analysis demonstrated inhibition of both chemotaxis and chemokinesis. The effect of PGE(2) was concentration dependent, and the inhibitory effect diminished with time. Other agents that increased fibroblast cAMP levels, including isoproterenol (10(-5) M), dibutyryl cAMP (10(-5) M), and forskolin (3 x 10(-5) M) had similar effects and inhibited chemotaxis 54.1, 95.3, and 87.0%, respectively. The inhibitory effect of PGE(2) on HFL1 cell chemotaxis was inhibited by the cAMP-dependent protein kinase (PKA) inhibitor KT-5720, which suggests a cAMP-dependent effect mediated by PKA. In summary, PGE(2) appears to inhibit fibroblast chemotaxis, perhaps by modulating the rate of fibroblast migration. Such an effect may contribute to regulation of the wound healing response after injury.

Acute exacerbations of asthma in adults: role of Chlamydia pneumoniae infection

Respiratory infections precipitate wheezing in many asthmatic patients and may be involved in the aetiopathogenesis of asthma. Several studies have demonstrated that viral infections may provoke asthma. Bacterial infections seem to play a minor role. However, Chlamydia pneumoniae has been recently reported as a possible cause of asthma. The aim of the present study was to evaluate the role of C. pneumoniae infection in acute exacerbations of asthma in adults. Seventy four adult out-patients with a diagnosis of acute exacerbation of asthma were studied. Acute and convalescent (> or = 3 weeks) serological determination of antibodies to cytomegalovirus, respiratory syncytial virus, adenovirus, influenza A and B, parainfluenza 1 and 3, Mycoplasma pneumoniae and Legionella pneumophila were performed by means of immunofluorescence tests. C. pneumoniae specific antibodies were detected by two microimmunofluorescence tests using a specific antigen (TW-183) and a kit with three chlamydial antigens. Pharyngeal swab specimens were also obtained for C. pneumoniae identification. Samples for bacterial culture were obtained in patients with productive cough (15 out of 74 patients). Fifteen patients (20%) presented seroconversion to at least one of the studied pathogens. Seven were found to be infected by virus, six by C. pneumoniae alone, and one by M. pneumoniae. One more patient showed seroconversion to C. pneumoniae and cytomegalovirus.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of intercellular adhesion molecule-1 (ICAM-1) by reactive mesothelial cells in pleural effusions

Reactive mesothelial cells in serous effusions have been assessed for their capacity to express intercellular adhesion molecule-1 (ICAM-1), when pleural cavities are involved in inflammatory and immune reactions. Cytospin smears prepared from 10 benign and 10 malignant effusion specimens were used in an immunocytochemical procedure. Mesothelial cells were positively immunolabeled by a monoclonal antibody to human ICAM-1, whereas lymphocytes clustered around them reacted positively with a monoclonal antibody to human Lymphocyte Function-associated antigen-1 alpha chain (LFA-1-alpha). The ICAM-1/LFA-1 interaction enables mesothelial cells to regulate leukocyte transmigration to and accumulation in serous cavities and therefore they are actively involved in the development of serous effusions.

Glyceraldehyde 3-Phosphate:NADP Reductase of Spinach Leaves : Steady State Kinetics and Effect of Inhibitors

The steady state kinetics of glyceraldehyde 3-phosphate:NADP(+) oxidoreductase (GNR) (EC 1.2.1.9) have been investigated. The enzyme exhibits hyperbolic behavior over a wide range of substrate concentrations. Double-reciprocal plots are nearly parallel or distantly convergent with limiting K(m) values of 2 to 5 micromolar for NADP(+) and 20 to 40 micromolar for D-glyceraldehyde 3-phosphate (G3P). The velocity response to NADP(+) as the varied substrate is however sigmoidal if G3P concentration exceeds 10 micromolar, whereas the response to G3P may show inhibition above this concentration. This ;G3P-inhibited state' is alleviated by saturating amounts of NADP(+) or NADPH. Product inhibition patterns indicate NADPH as a potent competitive inhibitor to NADP(+) (K(i) 30 micromolar) and mixed inhibitor towards G3P, and 3-phosphoglycerate (3PGA) as mixed inhibitor to both NADP(+) and G3P (K(i) 10 millimolar). The data, and those obtained with dead-end inhibitors, are consistent with a nonrapid equilibrium random mechanism with two alternative kinetic pathways. Of these, a rapid kinetic sequence (probably ordered with NADP(+) binding first and G3P binding as second substrate) is dominant in the range of hyperbolic responses. A reverse reaction with 3PGA and NADPH as substrates is unlikely, and was not detected. Of a number of compounds tested, erythrose 4-phosphate (K(i) 7 micromolar) and Pi (K(i) 2.4 millimolar) act as competitive inhibitors to G3P (uncompetitive towards NADP(+)) and are likely to affect the in vivo activity. Ribose 5-phosphate, phosphoenolpyruvate, ATP, and ADP are also somewhat inhibitory. Full GNR activity in the leaf seems to be allowed only under high photosynthesis conditions, when levels of several inhibitors are low and substrate is high. We suggest that a main function of leaf GNR is to supply NADPH required for photorespiration, the reaction product 3PGA being cycled back to chloroplasts.

[Clinical functional study of a new delayed-action preparation of "once a day" anhydrous theophylline in patients with chronic obstructive bronchopneumopathy]

A new long-acting theophylline formulation for once-daily administration has been tried in twenty patients with flare-ups of chronic obstructive bronchopulmonary disease (COPD). Clinical results were good and untoward side effects were not observed. Theophylline blood level was tested on the first day and once steady state had been achieved, and was always within the therapeutic range.

Solubilization and Purification of NAD(P)H Dehydrogenase of Cucurbita Microsomes

An NAD(P)H dehydrogenase stimulated by quinone (P Pupillo, V Valenti, L de Luca, R Hertel 1986 Plant Physiol 80: 384-389) was solubilized from washed microsomes of zucchini squash hypocotyls (Cucurbita pepo L.) by use of 1% Triton X-100. The solubilized enzyme remained in solution in aqueous buffer and could be purified by a combination of Sepharose 6B chromatography and Blue Ultrogel chromatography. Of the three peaks of activity eluted from the latter column with a salt gradient, peak 3 had 50% or more of the activity and was almost pure enzyme. The preparation examined in SDS-gel electrophoresis consisted of two types of subunits, a (molecular weight 39,500) and b (37,000) in equal amounts. Peak 2 was less pure but had a similar polypeptide pattern. The active protein is proposed to be a heterotetramer (a(2)b(2)) having a molecular weight of about 150,000, as found by gel exclusion chromatography. The purified enzyme can reduce several quinones, DCPIP, cytochrome c, and with best efficiency ferricyanide, and is therefore a diaphorase. The kinetics for the substrates are negatively cooperative with Hill coefficients n(H) = 0.55 +/- 0.05 for NADPH and 0.22 +/- 0.04 for duroquinone. A weak inhibition by p-hydroxymercuric benzoate and mersalyl (stronger with microsomal preparations) suggests the presence of essential sulfhydryl group(s). The possibility is discussed that the dehydrogenase is an NAD(P)H-P450 reductase or similar flavoprotein, and that it is responsible for the NADPH-cytochrome c reductase activity of plant microsomes.

Kinetic characterization of reduced pyridine nucleotide dehydrogenases (duroquinone-dependent) in cucurbita microsomes

Some properties of microsomal electron transfer chains, dependent for oxidase activity on addition of NADH or NADPH, duroquinone, and oxygen (L. De Luca et al., 1984, Plant Sci Lett 36: 93-98) are described. Activity is characterized by negatively cooperative kinetics toward reduced pyridine nucleotides, with limiting K(m) of 10 to 50 micromolar at pH 7.0 (increasing at lower pH), as well as toward duroquinone with limiting K(m) of 100 to 400 micromolar regardless of pH. Molecular oxygen is reduced by the enzyme complex with S(0.5) of about 30 micromolar and production of H(2)O and H(2)O(2), without superoxide involvement. The ratio NAD(P)H:O(2) averages 1.35 in the presence of KCN and 1.85 in its absence. The pyridine nucleotide specificity of the dehydrogenases has been investigated by kinetic competition experiments. Some enzyme heterogeneity was established for all preparations. At least two enzymes are detectable in plasma membrane-enriched fractions: a major NAD(P)H dehydrogenase having an acid pH optimum, and an NADPH dehydrogenase active around neutrality. Addition of Triton X-100 strongly enhances the activity over most of the pH scale, but depresses it increasingly at pH values higher than 8.0, to the effect that pH profile shows, under these conditions, a major peak at about pH 5.8 for both NADH and NADPH oxidase. Results with endoplasmic reticulum preparations are similar, except that they suggest the presence of still more activities at and above pH 7. The results are interpreted in terms of different complexes catalyzing electron transfer from NAD(P)H to O(2) without release of intermediates.

Glucose 6-phosphate dehydrogenase isozymes of maize leaves : some comparative properties

Two different forms of glucose 6-phosphate dehydrogenase (EC 1.1.1.49) have been purified from etiolated and green leaves, respectively, of 6-day maize (Zea mays L. cv Fronica) seedlings. The procedure includes an ammonium sulfate step, an ion exchange chromatography, and a second gel filtration in Sephadex G-200 in the presence of NADP(+) to take advantage of the corresponding molecular weight increase of the enzyme. The isozyme from etiolated leaves is more stable and has been purified up to 200-fold. Subunit molecular weight, measured by sodium dodecyl sulfate-gel electrophoresis, is 54,000. The active protein, under most conditions, has a molecular weight 114,000, which doubles to molecular weight 209,000 in the presence of NADP(+). The association behavior of enzyme from green leaves is similar, and the molecular weight of the catalytically active protein is also similar to the form of etiolated leaves.Glucose 6-phosphate dehydrogenase of dark-grown maize leaves isoelectric point (pI) 4.3 is replaced by a form with pI 4.9 during greening. The isozymes show some differences in their kinetic properties, K(m) of NADP(+) being 2.5-fold higher for pI 4.3 form. Free ATP (K(m) = 0.64 millimolar) and ADP (K(m) = 1.13 millimolar) act as competitive inhibitors with respect to NADP(+) in pI 4.3 isozyme, and both behave as less effective inhibitors with pI 4.9 isozyme. Magnesium ions abolish the inhibition.

Activation Kinetics of NAD-Dependent Malic Enzyme of Cauliflower Bud Mitochondria

NAD-dependent malic enzyme (EC 1.1.1.39) was obtained from isolated mitochondria of cauliflower buds (Brassica oleracea L., var. botrytis). The NAD-linked activity is accompanied by a minor NADP-linked activity. Some contaminant NADP-malic enzyme from the supernatant and the plasma membrane is usually present in crude mitochondrial preparations. NAD-dependent malic enzyme has been purified 38-fold by ammonium sulfate fractionation and gel permeation chromatography, to a specific activity up to 2 micromoles per minute per milligram.The nature of the activating effect of coenzyme A and dithiothreitol has been investigated. Both compounds act by decreasing the apparent Michaelis constants for l-malate and NAD(+) (and NADP(+)), V(max) remaining approximately constant. However, enzyme fully activated by dithiothreitol can still be stimulated up to 2.4-fold by coenzyme A treatment.Velocity versus substrate responses show hyperbolic kinetics under present assay conditions (pH 7.5, 2 millimolar Mn(2+)), but biphasic kinetics have been observed with enzyme purified in the presence of 10 millimolar dithiothreitol, suggesting enzyme heterogeneity with respect to an activated state. This condition is reverted to linearity by treatment with coenzyme A. K(m) values do not vary with changing concentrations of the second substrate. Enzyme molecular weight is 400,000 in the completely activated state and 200,000 in the ;inactivated' state; intermediate forms are also found. All coenzyme A derivatives tested are effective activators, showing activation constants lower than for coenzyme A itself. The concentration dependence of the activation is sigmoidal.