Approaching boiling point stability of an alcohol dehydrogenase through computationally-guided enzyme engineering

Enzyme instability is an important limitation for the investigation and application of enzymes. Therefore, methods to rapidly and effectively improve enzyme stability are highly appealing. In this study we applied a computational method (FRESCO) to guide the engineering of an alcohol dehydrogenase. Of the 177 selected mutations, 25 mutations brought about a significant increase in apparent melting temperature (ΔTm ≥ +3 °C). By combining mutations, a 10-fold mutant was generated with a Tm of 94 °C (+51 °C relative to wild type), almost reaching water's boiling point, and the highest increase with FRESCO to date. The 10-fold mutant's structure was elucidated, which enabled the identification of an activity-impairing mutation. After reverting this mutation, the enzyme showed no loss in activity compared to wild type, while displaying a Tm of 88 °C (+45 °C relative to wild type). This work demonstrates the value of enzyme stabilization through computational library design.

Grading as a Prognostic Factor: Review of 209 Primary Gastric Cancer Patients

Two hundred and nine cases of primary gastric cancer were treated surgically from January 1968 to December 1983 and analyzed retrospectively. All patients were followed up for a minimum of 5 years. There were 25 SI cases (12 %), 22 SII (10.5%), 55 SIII (26.3%) and 107 SIV (51.2%). Tumor grade according to Broders classification showed 50 cases of G1 lesions (23.9%), 44 G2 (21.1 %) and 115 G3 (55%). Patients with well differentiated G1 lesion, compared to G2-G3 patients, presented a greater incidence of T1-T2 tumors and decreased incidence of T4 tumors (p < 0.05). The lymph node involvement rate significantly increased with variation of T (p < 0.001) but not with tumor grade. Survival results correlated with tumor stage (p < 0.01) but not with tumor grade or histological type.

Structural and biochemical insights into 7β-hydroxysteroid dehydrogenase stereoselectivity

Hydroxysteroid dehydrogenases are of great interest as biocatalysts for transformations involving steroid substrates. They feature a high degree of stereo- and regio-selectivity, acting on a defined atom with a specific configuration of the steroid nucleus. The crystal structure of 7β-hydroxysteroid dehydrogenase from Collinsella aerofaciens reveals a loop gating active-site accessibility, the bases of the specificity for NADP(+) , and the general architecture of the steroid binding site. Comparison with 7α-hydroxysteroid dehydrogenase provides a rationale for the opposite stereoselectivity. The presence of a C-terminal extension reshapes the substrate site of the β-selective enzyme, possibly leading to an inverted orientation of the bound substrate. Proteins 2016; 84:859-865. © 2016 Wiley Periodicals, Inc.

Pyrrole- and indole-containing tranylcypromine derivatives as novel lysine-specific demethylase 1 inhibitors active on cancer cells

A new series of pyrrole/indole-containing tranylcypromine analogues is reported as potent and selective LSD1 inhibitors active in leukemia.

The 'gating' residues Ile199 and Tyr326 in human monoamine oxidase B function in substrate and inhibitor recognition

The major structural difference between human monoamine oxidases A (MAO A) and B (MAO B) is that MAO A has a monopartite substrate cavity of ~550 Å(3) volume and MAO B contains a dipartite cavity structure with volumes of ~290 Å(3) (entrance cavity) and ~400 Å(3) (substrate cavity). Ile199 and Tyr326 side chains separate these two cavities in MAO B. To probe the function of these gating residues, Ile199Ala and Ile199Ala-Tyr326Ala mutant forms of MAO B were investigated. Structural data on the Ile199Ala MAO B mutant show no alterations in active site geometries compared with wild-type enzyme while the Ile199Ala-Tyr326Ala MAO B mutant exhibits alterations in residues 100-103 which are part of the loop gating the entrance to the active site. Both mutant enzymes exhibit catalytic properties with increased amine K(M) but unaltered k(cat) values. The altered K(M) values on mutation are attributed to the influence of the cavity structure in the binding and subsequent deprotonation of the amine substrate. Both mutant enzymes exhibit weaker binding affinities relative to wild-type enzyme for small reversible inhibitors. Ile199Ala MAO B exhibits an increase in binding affinity for reversible MAO B specific inhibitors which bridge both cavities. The Ile199Ala-Tyr326Ala double mutant exhibits inhibitor binding properties more similar to those of MAO A than to MAO B. These results demonstrate that the bipartite cavity structure in MAO B plays an important role in substrate and inhibitor recognition to distinguish its specificities from those of MAO A and provide insights into specific reversible inhibitor design for these membrane-bound enzymes.

Structure-based redesign of cofactor binding in putrescine oxidase

Putrescine oxidase (PuO) from Rhodococcus erythropolis is a soluble homodimeric flavoprotein, which oxidizes small aliphatic diamines. In this study, we report the crystal structures and cofactor binding properties of wild-type and mutant enzymes. From a structural viewpoint, PuO closely resembles the sequence-related human monoamine oxidases A and B. This similarity is striking in the flavin-binding site even if PuO does not covalently bind the cofactor as do the monoamine oxidases. A remarkable conserved feature is the cis peptide conformation of the Tyr residue whose conformation is important for substrate recognition in the active site cavity. The structure of PuO in complex with the reaction product reveals that Glu324 is crucial in recognizing the terminal amino group of the diamine substrate and explains the narrow substrate specificity of the enzyme. The structural analysis also provides clues for identification of residues that are responsible for the competitive binding of ADP versus FAD (~50% of wild-type PuO monomers isolated are occupied by ADP instead of FAD). By replacing Pro15, which is part of the dinucleotide-binding domain, enzyme preparations were obtained that are almost 100% in the FAD-bound form. Furthermore, mutants have been designed and prepared that form a covalent 8α-S-cysteinyl-FAD linkage. These data provide new insights into the molecular basis for substrate recognition in amine oxidases and demonstrate that engineering of flavoenzymes to introduce covalent linkage with the cofactor is a possible route to develop more stable protein molecules, better suited for biocatalytic purposes.

Review article: anti-fibrotic agents for the treatment of Crohn's disease - lessons learnt from other diseases

BACKGROUND

The current therapies for Crohn's disease (CD) are mainly focused on blockade of inflammation. Fibrosis remains one of the major complications of CD often leading to surgery, affecting patients' quality-of-life.

AIM

To summarize the published data regarding the potential anti-fibrotic role of drugs commonly used in CD and the most effective anti-fibrotic drugs used in other diseases evaluating their potential use to treat intestinal fibrosis in CD.

METHODS

A literature search was performed in the PubMed, Medline, Cochrane and EMBASE databases, considering in vitro, animal and human studies on fibrosis in inflammatory bowel disease and other similar chronic pathologies.

RESULTS

Treatment of fibrosis in CD is limited to surgery or endoscopic dilatation, although some of the drugs currently used may have anti-fibrotic activity. In other diseases, anti-fibrotic agents are already used or are in preclinical or clinical trials. ACE inhibitors, Angiotensin Receptor Blockers, and HMG-CoA inhibitors merit further investigation in CD because of their role in preventing fibrosis in cardiovascular and renal diseases.

CONCLUSIONS

Anti-fibrotic drugs are under evaluation or already used in clinical practice in other chronic inflammatory diseases. In CD, there is a great need for investigation into agents that may prevent, reduce or reverse intestinal fibrosis.

Crystallization and preliminary X-ray analysis of an alditol oxidase from Streptomyces coelicolor A3(2)

Alditol oxidase is a 45 kDa enzyme containing a covalently bound FAD cofactor. This oxidase efficiently oxidizes a range of alditols to the corresponding aldoses. Owing to its substrate range and regioselectivity, this enzyme is an interesting candidate for biotechnological applications. Crystals of alditol oxidase from Streptomyces coelicolor A3(2) were obtained by the hanging-drop vapour-diffusion method and diffracted to 1.1 A resolution. The crystals belong to space group C2, with unit-cell parameters a = 107, b = 68, c = 58 A, beta = 94 degrees. Crystals of seleno-L-methionine-labelled alditol oxidase were obtained after seeding the crystallization drops with native microcrystals and showed a diffraction limit of 2.4 A.

Laboratory-evolved vanillyl-alcohol oxidase produces natural vanillin

The flavoenzyme vanillyl-alcohol oxidase was subjected to random mutagenesis to generate mutants with enhanced reactivity to creosol (2-methoxy-4-methylphenol). The vanillyl-alcohol oxidase-mediated conversion of creosol proceeds via a two-step process in which the initially formed vanillyl alcohol (4-hydroxy-3-methoxybenzyl alcohol) is oxidized to the widely used flavor compound vanillin (4-hydroxy-3-methoxybenzaldehyde). The first step of this reaction is extremely slow due to the formation of a covalent FAD N-5-creosol adduct. After a single round of error-prone PCR, seven mutants were generated with increased reactivity to creosol. The single-point mutants I238T, F454Y, E502G, and T505S showed an up to 40-fold increase in catalytic efficiency (kcat/Km) with creosol compared with the wild-type enzyme. This enhanced reactivity was due to a lower stability of the covalent flavin-substrate adduct, thereby promoting vanillin formation. The catalytic efficiencies of the mutants were also enhanced for other ortho-substituted 4-methylphenols, but not for p-cresol (4-methylphenol). The replaced amino acid residues are not located within a distance of direct interaction with the substrate, and the determined three-dimensional structures of the mutant enzymes are highly similar to that of the wild-type enzyme. These results clearly show the importance of remote residues, not readily predicted by rational design, for the substrate specificity of enzymes.

Structural studies on flavin reductase PheA2 reveal binding of NAD in an unusual folded conformation and support novel mechanism of action

The catabolism of toxic phenols in the thermophilic organism Bacillus thermoglucosidasius A7 is initiated by a two-component enzyme system. The smaller flavin reductase PheA2 component catalyzes the NADH-dependent reduction of free FAD according to a ping-pong bisubstrate-biproduct mechanism. The reduced FAD is then used by the larger oxygenase component PheA1 to hydroxylate phenols to the corresponding catechols. We have determined the x-ray structure of PheA2 containing a bound FAD cofactor (2.2 A), which is the first structure of a member of this flavin reductase family. We have also determined the x-ray structure of reduced holo-PheA2 in complex with oxidized NAD (2.1 A). PheA2 is a single domain homodimeric protein with each FAD-containing subunit being organized around a six-stranded beta-sheet and a capping alpha-helix. The tightly bound FAD prosthetic group (K(d) = 10 nm) binds near the dimer interface, and the re face of the FAD isoalloxazine ring is fully exposed to solvent. The addition of NADH to crystalline PheA2 reduced the flavin cofactor, and the NAD product was bound in a wide solvent-accessible groove adopting an unusual folded conformation with ring stacking. This is the first observation of an enzyme that is very likely to react with a folded compact pyridine nucleotide. The PheA2 crystallographic models strongly suggest that reactive exogenous FAD substrate binds in the NADH cleft after release of NAD product. Nanoflow electrospray mass spectrometry data indeed showed that PheA2 is able to bind one FAD cofactor and one FAD substrate. In conclusion, the structural data provide evidence that PheA2 contains a dual binding cleft for NADH and FAD substrate, which alternate during catalysis.

Transvaginal bone-anchored synthetic sling for the treatment of stress urinary incontinence: an outcomes analysis

OBJECTIVES

To evaluate the results and complications of a new transvaginal minimally invasive procedure for the treatment of stress urinary incontinence.

METHODS

Sixty-seven women aged 37 to 77 years underwent a pervaginal bone-anchoring synthetic sling procedure between April 1997 and February 1999. Sixty-three patients had a defect of the anatomic support, and 4 had iatrogenic intrinsic sphincteric deficiency (ISD). Patients were assessed at least 1 year postoperatively, underwent physical examination, and filled in the self-assessment questionnaire with the help of a nonpartisan health care provider. The questionnaire inquired about urine leakage, obstructive and irritative symptoms, quality of life, and satisfaction with the treatment received. The physician and questioner had no knowledge of each other.

RESULTS

Mean follow-up was 17 months. Perfect dryness was seen in 82% of patients with improvement in 9% and failure in 9%. Patients reporting a failed outcome were significantly older than those reporting improvement or cure (P = 0.01). All patients with ISD failed. Moderate obstructive symptom scores have been noticed in 31% of patients. Irritative voiding symptoms have been recorded in 22% of cured patients and 83% and 80% of improved and failed patients, respectively (P <0.001). Three percent of patients experienced pain during intercourse. Mild pelvic pain was found in 8% of patients. The only main complication of the operation was the vaginal erosion and sling removal in 16% of patients. Seventy-two percent of patients were completely satisfied with the treatment received.

CONCLUSIONS

This procedure allows a high cure rate in patients with urinary incontinence due to a defect of anatomic support, and it is unsuitable when incontinence is due to ISD. The only main complication came from the use of the gelatin-coated Dacron sling that resulted in vaginal erosion, often necessitating the sling removal. The use of different synthetic or nonsynthetic materials may be advisable.

[Can Helicobacter pylori infection be a risk factor for the severity of rheumatoid arthritis?]

AIM

In this study we assessed the effect of Helicobacter pylori eradication in patients with established rheumatoid arthritis (RA) in order to show a possible pathogenetic role of the infection in this disease.

METHODS

We recruited 31 patients with variable RA activity. Of them, 15 were Hp-positive (12 F and 3 M, mean age 55 +/- 10.6 years) and 16 Hp-negative (13 F and 3 M, mean age 54.2 +/- 9.1 years) on the basis of the concomitant positive or negative findings of both CLO-test and histology performed on both antral and corpus biopsies. The infected group was treated and the bacterium was considered eradicated when both tests were negative a month after therapy. We have evaluated the disease activity at baseline and during a total follow-up period of 16 months with check-points every 4-months and compared clinical and laboratory findings between the Hp-negative and the eradicated groups. Both groups were being treated with NSAIDs and prednisolone (< or = 7.5 mg/die) or its equivalents.

RESULTS

Hp-eradicated RA patients showed a progressive improvement overtime (p = 0.0009) of all clinical indices compared with baseline, while Hp-negative RA patients did not. At the 16-month checkpoint, the eradicated RA patients differed significantly (p < 0.006) from patients without Hp infection by all indices, except grip strength of the hands. Also all laboratory data improved significantly from baseline to the 16 month checkpoint (p < 0.03) within the Hp-eradicated group and between the two groups of eradicated and Hp-negative RA patients (p < 0.0007) except for Hb, aCL IgM and gamma-globulins.

CONCLUSIONS

Our data suggest that Hp infection is implicated in the pathogenesis of RA. On the basis of our data, the eradication of Hp should be recommended in infected RA patients.

Is intensive follow-up really able to improve prognosis of patients with local recurrence after curative surgery for rectal cancer?

BACKGROUND

Because more than 90% of local recurrences after curative surgery for rectal cancer appear within the first 36 months after surgery, an intensive and strict follow-up program during this period could improve early diagnosis and, thus, prognosis of patients.

METHODS

Of the 216 patients who underwent surgery for rectal cancer, 127 entered an intensive follow-up program (median follow-up: 42 months); the clinical outcome of the remaining 89 patients was reconstructed with the help of their general practitioners.

RESULTS

Fifty eight (26.8%) of the 216 patients who were treated with curative surgery alone developed a local recurrence; pelvic recurrences were prevalent. Eleven (30.5%) of the 36 patients who had recurrence during follow-up, and 6 of the 22 who had not undergone follow-up, had a reoperation with curative intent; the median survival was 19 months vs. 8 months, respectively (P = ns). Four (44.4%) curative reoperations were performed on the 9 asymptomatic patients and in 13 (26.5%) of the 49 cases with symptomatic local recurrences. Median survival was 15 months vs. 14 months, respectively (P = n.s). All patients except one (living after 42 months from reoperation) died within 48 months.

CONCLUSIONS

In our study, adherence to a strict follow-up program unfortunately proved to be ineffective for improving long-term survival for patients who underwent reoperation with curative intent.

Role of impression cytology during hypovitaminosis A

AIMS

Evaluation of the morphological damage to the ocular surface of patients operated for biliopancreatic diversion for pathological obesity and the correlation of impression cytology with vitamin A plasma levels, adaptometry, and other general variables.

METHODS

48 patients (15 males, 33 females, age range 21-73) and 34 normal subjects were examined with fluorescein and rose bengal, a plasma dose of vitamin A, and adaptometry. The results of the various tests were subdivided into three levels (0 = normal, 1 = moderately altered, 2 = seriously altered). The impression cytology and adaptometry results were correlated with vitamin A levels and other patient data (age, nutritional condition, time since operation, percentage weight loss). All the examinations were repeated after intramuscular therapy with vitamin A.

RESULTS

Corneoconjunctival alterations visible with fluorescein and rose bengal staining were present in 67.7% of cases, impression cytology alterations in 93.7%, adaptometric alterations in 82.2%; vitamin A plasma levels were below normal in 95.8% of cases. After the therapy with vitamin A a significant reduction was found for every examination. The correlation between impression cytology and adaptometry and vitamin A plasma levels and between corneoconjunctival alterations and vitamin A plasma levels was significant. There was no significant correlation between impression cytology and nutritional condition, age time since operation, and percentage weight loss.

CONCLUSION

These results show impression cytology is a specific indicator for hypovitaminosis A because it is not influenced by other factors related to the general condition of the patient. Many patients with hypovitaminosis A not demonstrating ocular symptoms of changes visible with fluorescein and rose bengal showed alterations with impression cytology.

Correlation between F/T-Psa and Echographically-Assessed Prostate Weight in the Diagnosis of Prostatic Cancer

The aim of this study was to check whether the combination of clinical-laboratory parameters enables better identification of patients with probable prostate cancer who should undergo echo-guided biopsy, thereby reducing the number of biopsies carried out.

Patients and methods

100 consecutive patients were recruited (mean age 68.2 ± SD 6.7) all with high PSA (mean: 9.3 ± SD 4.3 ng/ml), plus positive TR ultrasound in 85 patients and positive ER in 41 patients referred to our centre for echo-guided prostatic biopsy. Before the biopsy, all patients were sampled to asses the F/T-PSA value with the Immunolite method. Each patient underwent 6–8 echo-guided transrectal biopsies using the Tru-cut 18 G automatic gun. Prostatic weight was calculated echographically (A x B x C x 0.5236). In all, 122 biopsies were carried out in these 100 patients (mean: 1.22 ± SD 0.56). Data was statistically assessed with multiple and logistic regression with variables: age, T-PSA, F-PSA, F/T-PSA, ECT, ER, prostatic weight, number of biopsies per patient. From this analysis, F/T-PSA and prostatic weight proved to be correlated: further multiple regression analysis was carried out on these parameters.

Results

40 cases of prostate cancer were identified and 60 cases of BHP. The regression between the variable that depends on the histological result and the independent variables of F/T-PSA and prostatic weight was extremely significant (p < 0.001). In the light of the results, the following formula was worked out y = 1.077 - (0.025 x F/T - PSA) - (0.008 x prostatic weight). This formula has produced results between 0.04 and 0.9. With a cut-off value of 0.4, 33 prostate cancers were recognised out of 40 and 47 BHP out of 60. Sensitivity was 83%, specificity 78% and efficiency 80%.

Conclusions

F/T-PSA assessment and echographically determined prostatic weight enables a sufficiently sensitive identification to be made of prostate cancer patients who should definitely undergo a biopsy. It is also possible to select those who should be subject to strict follow-up, with consequent reduction (approx 50%) in the number of potential biopsies.

[Detection of Helicobacter pylori in 201 stomach biopsies using the polymerase chain reaction, histological staining (H&E/Giemsa) and immunohistochemistry]

Helicobacter Pylori is believed to be an essential etiologic agent of type B chronic gastritis and peptic ulcer disease in humans. Recent reports have also suggested a role for these organisms in the development of gastric carcinoma and MALT-Lymphoma. A variety of diagnostic procedures are used for the identification of Helicobacter Pylori in clinical samples. 201 gastric biopsy (164 antral and 37 body biopsy specimens) were obtained from 164 patients with endoscopic abnormalities. These samples were studied for the detection of the presence of Helicobacter Pylori by histological staining (EE/Giemsa), immunohistochemistry and PCR by using a primer pair derived from the nucleotide sequence of the Urease A gene of Helicobacter Pylori. Specific amplification of a 411 base pair DNA fragment from all strain of Helicobacter Pylori tested was achieved. Of the 201 gastric biopsy analyzed, 63 (31%) were infected with Helicobacter Pylori on the basis of both histological and immunohistochemical staining, and 81 (41%) were positive with PCR (P < 0.001). Our results support a role for PCR in the rapid and highly sensitive and specific identification of Helicobacter Pylori in gastric biopsy specimens.

[Critical review of treatment outcome in 54 patients with synchronous liver metastasis of colorectal cancer]

Short- and long-term results of the treatment of 54 patients (12.5%) with synchronous hepatic metastases were critically reviewed by means of retrospective analysis of 431 colorectal cancer patients surgically treated over a period ranging from January 1980 to December 1989. Incidence and stage of hepatic metastases (Gennari Classification, 1984) are not significantly correlated to stage (T3), grade (G2-G3) and mucinous colorectal tumours; but they are significantly correlated to metastatic lymph nodes (p < 0.01). Actuarial survival is significantly influenced by surgery (p < 0.01) and stage of liver metastases (p < 0.05). The restriction of preoperative exclusion criteria and the simultaneous surgical treatment of primary colorectal and secondary hepatic metastases seem to be responsible for the high rates of operative mortality.

Upper abdominal surgery: does a lung function test exist to predict early severe postoperative respiratory complications?

We evaluated the capacity to predict severe respiratory complications (SRCs) following upper abdominal surgery (UAS) by using the results of a respiratory questionnaire and preoperative pulmonary function tests. Lung volumes, flows and transfer factor of the lung for carbon monoxide (TL,CO,sb) were assessed in 361 consecutive adult patients (248 males and 113 females). SRCs were diagnosed 24 h after UAS by clinical examination and chest radiography. Univariate and stepwise multiple logistic regression analyses were performed to estimate the odds ratio (OR) and 95% confidence interval (95% CI) of each single input variable, and to determine which indices best predicted outcome. These patients had a 1% mortality rate and 14% incidence of SRCs, with a male:female ratio of 0.86. The best predictors for SRCs by multiple analysis were: preoperative current hypersecretion of mucus (OR=133; p<0.0001); an increase in residual volume (RV) (OR=3.11; p=0.01); and, to a lesser extent, low percentage of predicted values both of forced expiratory volume in one second (FEV1 % pred) and TL,CO,sb. The algorithm thus obtained (logit theta) was extremely sensitive (84%), specific (99%), and accurate (95%) for preoperative prediction of SRCs. We have found that preoperative current hypersecretion of mucus and pulmonary hyperinflation, and to a lesser extent percentage predicted values both of forced expiratory volume in one second and transfer factor of the lung for carbon monoxide, have a significant predictive capacity for severe respiratory complications following upper abdominal surgery.

Radical nephrectomy for renal cell carcinoma: long-term results and prognostic factors on a series of 328 cases

OBJECTIVES

A series of 328 evaluable patients with renal cell carcinoma operated by radical transabdominal nephrectomy with regional lymphadenectomy was reviewed to assess the prognostic significance of various pathologic parameters (pT, N, M, G and venous involvement) and the value of lymphadenectomy and of surgery of venous tumor thrombus.

PATIENTS AND METHODS

The complete charts of 328 patients with renal cell carcinoma available to follow-up, who were operated between 1970 and 1993, were reviewed. All patients underwent transabdominal extrafascial nephrosurrenalectomy and in all but 14 metastatic ones a regional retroperitoneal lymphadenectomy was performed. Surgery of venous tumor thrombus was performed in 79 patients. Life expectancy according to pT stage, pN stage, M stage, nuclear grade and venous involvement was calculated by means of the life tables method and differences in survival were evaluated by means of the log rank test. Correlation analysis and multivariate data analysis according to the Cox model were also performed.

RESULTS

Overall survival of the 328 patients was 50.70% at 5 years, 35.10% at 10 years and 29% at 15 years. At multivariate data analysis the most important prognostic factors is the presence of metastases (8% survival at 5 years and no patient surviving more than 7 years after surgery), tumor grade was the second prognostic factor and statistically significant differences were also found at life tables analysis among G1, G2 and G3 tumors. Local tumor stage was the third leading prognostic factor at multivariate data analysis and statistically significant differences were also found at life tables analysis. Nodal and venous involvement had only minor importance at multivariate data analysis although statistically significant differences were found at life tables analysis between the pN+ and the pN0 patients, also in the absence of venous involvement and distant metastases. Anyway survival of the pN + M0V0 patients was satisfactorily high (53.20% at 5 years, 39.10% at 10 years and 16% at 15 and 20 years). In patients with venous involvement no differences in survival were observed depending on the level reached by the tumor thrombus; differences in survival were observed between patients with venous involvement alone (38% surviving at 5 and 10 years) and patients who also had nodal or distant metastases (5.20% at 5 years and 0% at 10 years).

CONCLUSIONS

From the review of our series it seems that the most important prognostic factors are synchronous metastases, tumor grading and the completeness of tumor exeresis. In fact, the low impact on survival of nodal involvement by itself is probably due to the completeness of lymphadenectomy. The value of regional lymphadenectomy is sustained by the high long term survival of N + M0V0 patients. Regarding venous involvement, it seems that V+ patients free from nodal and distant metastases may benefit from radical surgery, which on the contrary has only minimal impact on survival of V+M+/N+ patients.

Human breast cancer: prognostic significance of DNA ploidy compared with c-erbB2 expression, Cathepsin D and silver-binding nucleolar organizer regions (AgNORs)

We evaluated breast cancer specimens from 150 patients after a follow-up more than 10 years, by means of DNA flow cytometry, immunohistochemistry (cerbB2 and Cathepsin D) and argyrophilic (AgNORs) methods. In univariate analysis all indexes studied provide prognostic information about the disease free survival, whereas in the multivariate Cox model the DNA Index is the most important prognostic factor. We conclude that the data obtained from DNA flow cytometry, associated with other parameters, can be of greatest importance for the decision an the level of aggressiveness of adjuvant therapy for the decision an the level of aggressiveness of adjuvant therapy for a individual patients.

Comparative DNA analysis of breast cancer by flow cytometry and image analysis

Measurement of DNA ploidy can be performed either with Flow Cytometry (FCM) and Image-Analysis (IA); both methods provide prognostic information in primary breast cancer. We compared the results of quantitative DNA analysis of formalin fixed, paraffin embedded tissue from 62 invasive ductal breast cancers. For FCM nuclear suspensions from disaggregated tumor were stained with Propidium Iodide and analyzed by means of Ortho Cytoron Absolute. For IA nuclear suspensions were stained by the Feulgen method and analyzed by means of Vidas system. We found a good correlation between flow cytometry DNA Index and Histogram Type, according to Auer classification (rs = 0.65, p < 0.001) and between DNA Index and Grading of Malignancy (MG) which had been measured by Bocking's algorithm (rs = 0.38, p < 0.05). Concerning to disease free survival (DFS), flow cytometric DNA Index showed a better correlation (rs = 0.56, p < 0.001). We concluded that the two methods provide comparable results, but offer individual advantages and are complementary for analyzing DNA ploidy in breast cancer.

[Medical students and psychiatry. A survey of students' opinion]

In the last years research on the didactics of Psychiatry and opinions of medical students on Psychiatry has gained great interest. The authors think that this research could be useful for the improvement of didactics, for better understanding the meanings of professional choice, the identity of psychiatrist and their relationship with colleagues in other medical field. The goal of this research work was a preliminary survey of Genoese University Medical Student's opinions about psychiatry didactics, and choice of specialization. A questionnaire was submitted to all the students who passed Clinical Psychiatry examination in the period from November 1987 to December 1988. The students were divided in two randomized groups: the first group of students (224) was submitted to the questionnaire immediately after Clinical Psychiatry examination; while to the second group of students (66) the questionnaire was mailed. The aim of the questions was to assess the student's opinions on psychiatry, psychoanalysis, psychotherapy, the career they wanted to take up, and the difficulties of studying psychiatry: 69% of the students of the first group and 42% of the students of the second group answered the questionnaire. Female students answered that they preferred psychiatric specialization more than their male colleagues did, but the difference has no statistical importance. In most cases, the students who answered that they have taken into account psychiatry as a choice of specialisation, are more interested in medical specialties (primary care, etc.) than in surgical specialties. Most of the medical students declare some emotional troubles (anxiety, sleeplessness, problem in social relations).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of aging on some specific and nonspecific mechanisms of the host defense system in 146 healthy subjects

The influence of aging on some parameters of systemic host defense mechanisms, i.e. white cell counts, lymphocyte subpopulations, delayed-type hypersensitivity (DTH), polymorphonuclear and mononuclear leukocyte functions, was evaluated. One hundred and forty-six healthy volunteers (60 men and 86 women), aged 25-100 years, were enrolled. None of the subjects had taken any drug in the month before the study. Subjects were divided into three age groups: 25-45, 46-65 and 66-100 years. Groups were comparable in size, and sex distribution was similar throughout all age groups. Elderly people were 51 healthy volunteers between the ages of 66 and 100 years (mean age 79.2). Younger people were 41 subjects between the ages of 46 and 65 years (mean age 54.3) and 53 between the ages of 25 and 45 years (mean age 32.7). As for the comparison between sexes, no significant differences in the values of the studied parameters were found between males and females (p > 0.05). Only quantitative DTH data, i.e. the number of antigens producing positive reactions and the score (sum of positive reaction diameters), were significantly (p < 0.05) reduced in responsive females when compared to males. Aging did not affect white cell counts, lymphocyte subsets and many phagocytic functions, i.e. phagocytosis frequency and index, nitroblue tetrazolium reduction, superoxide production, microbicidal activity against bacteria and yeasts. A significant decrease (p < 0.05) in the chemotactic response to serum-derived chemotactic factors was observed in aged people in comparison to younger subjects. Anergy was more frequent in older (about 29%) than in younger (5-9.4%) healthy volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple tumour markers for diagnosis, management and follow-up of potentially resectable lung cancer

The present prospective study has been carried out to evaluate the role of tumour markers in the preoperative assessment and follow-up of patients with potentially resectable lung cancer. The carcinoembryonic antigen (CEA), neuron specific enolase (NSE), and tissue polypeptide antigen (TPA) have been preoperatively measured in 133 lung cancer patients and in 75 healthy smokers. The same tumour markers have been serially determined during the 12 to 30 month-follow-up of 53 subjects who had a complete resection. In screening for localized lung cancer, TPA determination was the single most accurate diagnostic test. The combined measurement of several tumour markers did not result in a greater diagnostic accuracy of the assay. In predicting lung cancer unresectability, CEA, though being the most suitable test, allowed preoperative detection of only one third of patients with unremovable tumours. In monitoring the postresectional course of subjects who had a complete resection, the combined measurement of TPA and NSE proved to be a very reliable predictor of disease recurrence.

[Expression of P53 protein in cutaneous melanoma]

P53 protein in cutaneous melanoma. We report the results of an immunohistochemical analysis about the nuclear phosphoprotein P53 expression performed on 48 primary and 10 metastatic cutaneous melanoma in order to assess the prevalence of the expression of mutant P53 protein (m-P53) in this skin tumour. In our study m-P53 was found in about 46% of primary tumours without any significant relationship with the corresponding metastatic lesions. Therefore the P53 count in cutaneous melanoma is not a prognostic marker of tumour spread and aggressiveness.

Nucleolar organizer regions: a prognostic factor in infiltrating ductal carcinoma in the breast

By means of an AgNOR technique, the authors have carried out a retrospective study on proliferative activity in 170 cases of infiltrating ductal breast carcinoma (so-called carcinoma NOS). The follow-up period was 138 months. A statistically significant correlation was found between AgNOR score and outcome of the disease ("vital status"), clinical stage and OS respectively. By means of discriminant analysis a threshold value of AgNOR score was identified (= 9.5) which distinguished two risk groups among the cases under examination. Those cases with an average AgNOR score below the threshold value showed a favourable prognosis. The cases with an AgNOR score greater than 9.5 had an unfavourable outcome. The authors suggest that AgNOR score may be used as a prognostic parameter in breast carcinoma.

Extension of lymph node dissection and survival in primary gastric cancer

The histories of 429 patients who underwent surgery for primary gastric cancer at our ward from January 1970 to December 1985, were reviewed. All patients underwent surgery: potentially curative surgery, 54.8%, non-curative resection, 18.2%; palliative surgery, 27%. Nodal status was as follows: N0, 28%; N1, 17.7%; N2, 44.5%; N3, 9.8%. The incidence of N0 cases was significantly increased in Stage T1 and T2 disease compared to Stage T3 and T4 lesions (p < 0.001). In Stage T3 and T4 patients the incidence of distant metastases increased if lymph node involvement was also present (p < 0.005). In patients without nodal metastases 5-year survival was 70% (median survival: 60+ months) whereas, in patients with lymph node involvement survival was 32% (median survival: 24 months) (p < 0.001). Our data suggest that elective extensive lymph node dissection (R2) is indicated in all patients because survival is improved by this procedure. We recommend R3 lymph node dissection only in macroscopic N3 node involvement patients.

[The use of different suture materials in thyroid surgery. A statistical evaluation of the immediate and long-term results]

Six groups of patients for a total of 120 cases were examined for cervical wound suture results. Different synthetic absorbable sutures and different suture techniques were employed. Good aesthetic results were always obtained in long-term follow-up. The patients sutured with Polydioxanone, a monofilament with prolonged breaking strength retention, had a lower incidence of local complications.

Counting the nucleolar organizer region-associated proteins is a prognostic clue of malignant melanoma

BACKGROUND AND DESIGN

The nucleolar organizer regions (NORs) are chromosomal loops of DNA to which acidic proteins are associated that are seen by silver staining as black dots within the nucleoli (hereafter, these silver-staining NORs will be referred to as AgNORs). As their size and number reflect cell and nuclear activity, their counting in paraffin sections is regarded as a useful tool for diagnosing and prognosing malignant tumors. We counted AgNORs in 98 patients with stage I melanoma, followed up to an average of 73 months, to verify whether the number of AgNORs is of prognostic value.

RESULTS

The number of AgNORs averaged 2.792 +/- 0.901 in the 64 patients without metastases and 4.889 +/- 1.403 in the 34 with metastases. In patients with counts higher than 3.62, there was an 82% probability of metastases developing.

CONCLUSION

The technique is fast, simple, and reproducible with easily available reagents and standard light microscopy. In our population, AgNOR counts constituted a more accurate prognostic indicator than Clark's level and Breslow's thickness. Confirmation in a new population is needed.

Glutaraldehyde-tanned mandril-grown grafts as venous substitutes

The present study was performed to evaluate the potential of glutaraldehyde-tanned mandril-grown grafts as caval substitutes. Short-term experiments consisted of 30 tubular grafts (35 x 8 mm), either of tanned collagen or polytetrafluoroethylene, that were sutured in the infrarenal inferior vena cava of pigs and removed 1 hour after implantation. There was no significant difference between the extent of the thrombus-lined graft surface in the biologic group and that in the polytetrafluoroethylene group. The amount of inner thrombus on tanned collagen grafts was significantly correlated to platelet activity. Long-term experiments involved 30 similar segments of both materials, which were sutured in the inferior vena cava and harvested 7, 14, 28, 56, and 112 days after operation. The 112-day patency rate of collagen grafts was 67%. The 56-day patency rate of polytetrafluoroethylene grafts was 16%. The difference was statistically significant (p less than 0.01). Collagen grafts were lined by a thin neointima (200 micron) in all but two cases. The neointima was completely endothelialized within 4 weeks from implantation. In conclusion, tanned collagen grafts may represent a suitable material for venous replacement.

Chest wall involvement by lung cancer: computed tomographic detection and results of operation

The aim of this prospective study was to evaluate: (1) the role of computed tomographic scanning in predicting chest wall invasion by peripheral lung cancer and (2) the results of operation according to the depth of chest wall involvement and other potential indicators of long-term survival. One hundred twelve patients with non-small cell lung cancer adjacent to the pleural surface who underwent computed tomographic scanning and subsequent thoracotomy were entered into this study. Tumor invasion was confined to the visceral pleura in 53 patients, to the parietal pleura in 18 patients, and to intercostal muscles in 25 patients; invasion extended beyond this layer in 16 patients. The computed tomographic criteria for chest wall invasion were (1) obliteration of the extrapleural fat plane, (2) the length of the tumor-pleura contact, (3) the ratio between the tumor-pleura contact and the tumor diameter, (4) the angle of the tumor with the pleura, (5) a mass involving the chest wall, and (6) rib destruction. The computed tomographic criteria 1 and 3 were significantly related to pathologic findings. Sensitivity was 85% for criterion 1 and 83% for criterion 3, specificity being 87% and 80%, respectively. Long-term survival of patients with T3 disease critically depended on the lymph node state and completeness of resection. The adenocarcinoma cell type and the T4 category were unfavorable prognostic factors. The depth of chest wall invasion did not affect survival, except for extensive rib and soft tissue infiltration. En bloc resection yielded better results than discontinuous resection.

Nucleolar organizer regions (NORs) in normal and pathological liver: a quantitative analysis

By means of a silver staining method, Nucleolar Organizer Region-associated proteins (NORs) have been evaluated on paraffin sections of a series of 58 ultrasound-guided liver biopsy specimens. These included 12 normal livers, 12 cirrhotic livers, 12 cases of chronic hepatitis and 22 cases of hepatocellular carcinoma. A significant difference (P less than 0.001) was found between the mean AgNOR scores of the normal and pathological biopsies, and between the non-neoplastic and the carcinomatous lesions. The authors suggest that AgNOR counts, in combination with conventional histocytological criteria, may be a useful method in the diagnosis of liver diseases.

[The prognostic value of Jass' histopathological classification of cancer of the left colon and rectum]

Histological material from 121 patients who underwent surgery for cancer of the left colon and rectum was reexamined by two pathologists according to criteria put forward in Jass' histopathological classification. A prevalence of Jass' grades II (36.4%) and III (47.9%) were observed in this series. There was no correlation between the site of neoplasia but there was a clearly increased incidence of advanced stages C and D according to Dukes-Kirklin's classification within Jass' grades II, III and IV (p less than 0.005) and growth pattern, but not for the configuration of tubules. The new histopathological model proved to be more reliable in prognostic terms in the case of cancer of the rectum compared to that of the left colon, but at present its clinical significance is limited to specifying the site and stage of the neoplasia. The latter was found to be the most reliable prognostic parameter.

A seasonal pattern in the onset of polymyalgia rheumatica

The seasonal distribution in the onset of polymyalgia rheumatica (PMR) was determined in 58 patients with the disease and compared with that in 44 patients affected by rheumatoid arthritis of elderly onset (EORA). Thirty six (62%) cases of PMR developed during May to August; by contrast, only 14 (31%) cases of EORA developed in the same months, this latter disease failing to show any seasonal clustering. The monthly distribution of PMR correlated with outside temperature and hours of sunshine. These data suggest that PMR might be triggered by such factors as actinic damage of superficial vessels or infective agents with a seasonal cycle. Finally, the summer clustering of PMR may be helpful in the differential diagnosis from EORA.

Radical extensive surgery for renal cell carcinoma: long-term results and prognostic factors

We studied 200 consecutive patients with renal cell carcinoma who underwent radical nephrectomy and extensive lymphadenectomy. Of the patients 25% already had distant metastasis at operation. Higher T stages tended to be associated with positive nodes (p less than 0.01) and distant metastasis (p less than 0.001). However, in patients with stage N0M0V0 tumors we found no statistically significant difference in survival in relationship to the T stage of the disease (5-year survival: stage T1 80%, stage T2 68% and stage T3 70%). Of all patients 10% had positive nodes without distant metastases and no venous spread of the tumor, and the 5-year survival rate was 52%. The 5-year survival rate of patients with distant metastases was 7%. Patient survival in the presence of a vena caval tumor thrombus is similar to that of patients with distant metastases. Based on our results the different stages in disease progression may be classified as having a good prognosis--intracapsular tumors (stages T1 to T2, N0M0V0) and tumors with involvement of perirenal fat (stage T3N0M0V0), an intermediate prognosis--tumors with nodal metastases alone (stages T1 to T3, N1 to 2, M0V0) and a poor prognosis--tumors with venous invasion and/or distant metastases. Histological grading and size of tumor can be used to assess prognosis but are not more accurate than pathological staging.

Nucleolar organizer regions and Ki-67 immunostaining in ductal breast cancer: a comparative study

53 cases of invasive ductal (NOS) carcinomas of the breast were studied by means of an immunostaining method with Ki-67 monoclonal antibody and an argyrophilic method for the demonstration of Nucleolar Organizer Regions (AgNORs). The percentage of cancer cells with nuclear Ki-67 immunoreactivity and the mean number of NORs for each tumour were statistically related. The data obtained showed a good correlation between Ki-67 index and NOR score (rS = 0.47 - P less than 0.001). The authors suggest that the AgNOR method--which is applicable to routinely processed material--might effectively substitute Ki-67 immunostaining as a marker of cell proliferation in ductal breast cancer.

Wavefront propagation in an activation model of the anisotropic cardiac tissue: asymptotic analysis and numerical simulations

In this paper we present a macroscopic model of the excitation process in the myocardium. The composite and anisotropic structure of the cardiac tissue is represented by a bidomain, i.e. a set of two coupled anisotropic media. The model is characterized by a non linear system of two partial differential equations of parabolic and elliptic type. A singular perturbation analysis is carried out to investigate the cardiac potential field and the structure of the moving excitation wavefront. As a consequence the cardiac current sources are approximated by an oblique dipole layer structure and the motion of the wavefront is described by eikonal equations. Finally numerical simulations are carried out in order to analyze some complex phenomena related to the spreading of the wavefront, like the front-front or front-wall collision. The results yielded by the excitation model and the eikonal equations are compared.

Prognostic value of the Jass histopathologic classification in left colon and rectal cancer: a multivariate analysis

Variables correlated to survival were studied in 121 patients who had undergone potentially curative surgery for left colon and rectal cancer. To investigate the prognostic value of the parameters both univariate and multivariate analysis were carried out. Minimum follow-up was 5 years. Multivariate analysis showed that while disease stage (p less than 0.0001) and site of primary tumor (p less than 0.0006) independently influenced survival, type of surgical procedure and histopathologic grade had no impact on survival. Jass histopathologic classification predicted survival for patient group I and IV whereas no significant relationship was observed for group II and III, which, in our series, were the most frequently encountered groups. Of the three parameters considered for Jass classification, tubule configuration, pattern of tumor growth and lymphocytic infiltration, only the latter was significantly correlated to survival (p less than 0.005). Different results were obtained when the prognostic values of Jass group was investigated separately for the 49 patients with adenocarcinoma of the left colon and the 72 patients with rectal cancer. Further investigation is required before routine clinical application of the Jass classification can be recommended.

[Colorectal cancer: prognosis after curative surgical treatment without extended elective lymphadenectomy in patients in Dukes C stage]

A retrospective analysis has been carried out on a group of 103 Dukes C cases from a series of 412 patients with colorectal carcinoma, operated on from January 1970 to November 1983. The 5-year survival rate was 32% in patients who had a curative resection (median survival: 24 months). Larger numbers of lymph nodes were obtained with right or left colectomy. As regards the treatment of rectal cancer, similar numbers of nodes were obtained either with anterior resection or with Miles' operation. Prognosis was significantly correlated to tumor location, number of involved nodes (p less than 0.01) and grading of the primary tumor (p less than 0.01). The use of extended left colectomy with elective abdominopelvic lymphadenectomy was associated with a small raise of survival and a definite increase of perioperative morbidity and mortality compared to conservative surgical resection.

[Sessile tubulo-villous polyps in the rectum: problems of diagnosis and treatment. Personal experience]

A retrospective analysis was performed on 22 patients (mean age 65) in whom preoperative rectosigmoidoscopy had diagnosed tubulovillous rectal polyp. In 12 cases the polyps were removed transanally and the remaining 10 were subjected to laparotomy. The incidence of error in the preoperative histological diagnosis was 18.2% (9% for the nature and 10% for degree of dysplasia of the polyp). There were 25% recurrences after transanal exeresis, 10% after laparotomy. Total survival at 42 months was 86.3%. The study confirms the validity of transanal exeresis of tubulovillous polyps of the rectum assuming careful preoperative patient selection.

[Quantitative evaluation of the nucleolus organizer regions (NORs) in malignant melanoma of the skin: is it a new prognosis index?]

Nucleolar Organizer Region-associated proteins (NORs) have been evaluated on paraffin sections of a series of cutaneous malignant melanomas, stage IA at the time of the initial diagnosis. A significant difference (P less than 0.001) was found between the numbers of AgNORs in the cases which developed metastases and those without metastases: increasing values of AgNORs representing increased risk of metastases.

Incidence of residual defects determining the clinical outcome after correction of tetralogy of Fallot: postoperative late follow-up

The postoperative results in 150 patients who had repair of tetralogy of Fallot (mean follow-up, 10.2 +/- 2.6 years) were defined as good in 71.3%, fair in 20.7%, and unsatisfactory in 8.0% on the basis of clinical criteria. Ninety-six percent of the patients are socially active, 92.0% have a good exercise tolerance, and 79.3% participate in sports. Data from 78 postoperative hemodynamic studies show mild right ventricular dysfunction in almost all patients examined. Peak systolic right ventricular/left ventricular pressure ratio decreased in the postoperative period in 65.4% of patients, remained unchanged in 3.8%, and increased in 30.8%. Minimal residual anomalies can modify the prognosis substantially. Of our patients, 53.3% of those with a shunt (p less than 0.05), 37.5% of those with stenosis (not significant), and 53.8% of those with pulmonary incompetences (p = not significant) have fair or unsatisfactory results. The associated defects are particularly unfavorable. Rhythm and conduction disturbances have resulted in fair or unsatisfactory results in 65.1% of patients. Such a disturbance occurring soon after bypass must be considered an incremental risk factor: 52.9% of patients seen with rhythm and conduction disturbances show the same disturbances later (p less than 0.001).

Factors influencing local recurrence after curative surgery for rectal cancer

The histories of 90 consecutive patients who underwent curative surgery for rectal cancer from January 1975 to December 1981 were reviewed. Twenty of 90 patients (22.2%) recurred locally. The site of the primary lesion and tumor differentiation are the most important factors influencing local recurrence. Median survival from recurrence was 3 months and no patient was alive after 15 months. No significant difference in survival was observed in patients surgically treated for recurrence compared to untreated patients.