Flexural strength and elastic modulus evaluation of structures made by conventional PMMA and PMMA reinforced with graphene

OBJECTIVE

The aim of this study was to compare both the elastic modulus (EM) and the flexural strength (FS) of two materials used in dental prosthesis, namely polymethylmethacrylate (PMMA) and polymethylmethacrylate reinforced with graphene (G-PMMA).

MATERIALS AND METHODS

Twenty rectangular samples were manufactured by a milling machine and divided into two groups (n= 10/group): Group 1, PMMA; Group 2, G-PMMA. The specimens were subjected to a three-point bending test conducted in the elastic range to evaluate EM. A similar test was protracted until fracture to evaluate FS. Data on EM and FS were statistically analyzed with independent-samples t-test in order to compare the two groups. A scanning electron microscope (SEM) (5.00 kx and 1.00 kx magnification) was used to evaluate the morphology of sample's fracture.

RESULTS

Compared to PMMA samples, each G-PMMA sample showed significantly higher values of FS (p <0.001) and EM (p <0.001). SEM images analysis showed an inhomogeneous fracture morphology in G-PMMA samples.

CONCLUSIONS

The results show that G-PMMA is a promising material to be used for prosthetic purposes. This is demonstrated by a significant increase in both peak load and bending stiffness, resulting from the bending test performed on G-PMMA samples. Furthermore, the latter exhibit greater homogeneity in their mechanical behavior, supporting the potential value of this material in dental prosthesis.

[Occupational cancer. The role of the occupational physician in systematic search and aetiological diagnosis of lung cancer. Analysis of a case list]

BACKGROUND

About 15% of lung cancers (LC) might be attributable to occupation. However, clinical practice shows that LC percentage for which occupational aetiology is recognized is lower than expected.

OBJECTIVES

To address the role of Occupational Physicians (OP) in systematic search and aetiological diagnosis of LC.

METHODS

The search was carried out at a university hospital in Brescia, northern Italy, a highly industrialized area with many workers potentially exposed to occupational lung carcinogens. Through short occupational history forms, physicians of various departments refer all new cases of primary LC to OP When occupational exposure to lung carcinogens is presumed, the OP evaluates the case at the occupational health clinic and sends clinical reports to notifying physicians, containing aetiological diagnosis and indications for medico-legal obligations.

RESULTS

Before 1998, few cases were referred to the OP and even less were compensated. The search yielded 1502 LC; after screening, full occupational health evaluation was performed in 693 cases: occupational aetiology was recognized in 182 (26%). Risk factors were silica, asbestos, polycyclic aromatic hydrocarbons, truck driving, painting, road paving; many workers were exposed to multiple carcinogens. 48 cases were compensated, many others are under litigation.

CONCLUSIONS

A systematic LC search made it possible to: reach an aetiological diagnosis and reduce the gap between expected LC and those reported/compensated; inform health authorities and undertake preventive action in workplaces; detect sentinel events; provide epidemiological data at community level; promote cooperation among health professionals (oncologists, surgeons, pneumologists, general practitioners, plant OP); increase teaching opportunities for medical students, those taking a specialisation course in occupational health; provide counselling and expert opinions for individual subjects, trade unions, employers, law courts.

Malignant mesothelioma in 2004: How advanced technology and new drugs are changing the perspectives of mesothelioma patients. Highlights from the VIIth Meeting of the International Mesothelioma Interest Group

Malignant mesothelioma (MMe) is a seemingly uncommon tumour whose incidence has in fact increased steadily and progressively over the last 30 years. Indeed, an actual "epidemic" is expected in the next 20 years, with over 1300 new cases a year till 2020 at least. Despite unquestionable improvement in the diagnostic methods at our disposal and the availability of new treatment strategies, the prognosis of MMe patients remains dramatically poor. For all the above reasons, translational research is the key to success; indeed, ever increasing knowledge of the molecular mechanisms underlying MMe pathogenesis could lead (and is actually leading) to new, hopefully more active, treatment options. To foster discussion among investigators working in this field, and to exchange different viewpoints concerning the newest advances in MMe pathogenesis and treatment, the VII International Mesothelioma Interest Group (IMIG) meeting was held in Brescia (Italy) between 24 and 26 June 2004 in cooperation with the Italian Group for the Study and Therapy of MMe (GIMe). The aim of this report is to summarize the most significant advances in the different disciplines applied to MMe presented and discussed during the IMIG meeting and how these advances will be changing the perspective of patients with MMe.

Talcage by medical thoracoscopy for primary spontaneous pneumothorax is more cost-effective than drainage: a randomised study

Simple thoracoscopic talcage (TT) is a safe and effective treatment of primary spontaneous pneumothorax (PSP). However, its efficacy has not previously been estimated in comparison with standard conservative therapy (pleural drainage (PD)). In this prospective randomised comparison of two well-established procedures of treating PSP requiring at least a chest tube, cost-effectiveness, safety and pain control was evaluated in 108 patients with PSP (61 TT and 47 PD). Patients in both groups had comparable clinical characteristics. Drainage and hospitalisation duration were similar in TT and PD patients. There were no complications in either group. The immediate success rate was different: after prolonged drainage (>7 days), 10 out of 47 PD patients, but only 1 out of 61 TT patients required a TT as a second procedure. Total costs of hospitalisation including any treatment procedure were not significantly different between TT and PD patients. Pain, measured daily by visual analogue scales, was statistically higher during the first 3 days in TT patients but not in those patients receiving opiates. One month after leaving hospital, there was no significant difference in residual pain or full working ability: 20 out of 58 (34%) versus 10 out of 47 (21%) and 36 out of 61 (59%) versus 26 out of 39 (67%) in TT versus PD groups, respectively. After 5 yrs of follow-up, there had been only three out of 59 (5%) recurrences of pneumothorax after TT, but 16 out of 47 (34%) after conservative treatment by PD. Cost calculation favoured TT pleurodesis especially with regard to recurrences. In conclusion, thoracoscopic talc pleurodesis under local anaesthesia is superior to conservative treatment by chest tube drainage in cases of primary spontaneous pneumothorax that fail simple aspiration, provided there is efficient control of pain by opioids.

Expression of glycoprotein 90K in human malignant pleural mesothelioma: correlation with patient survival

The expression of the tumour-associated glycoprotein 90K in patients with malignant pleural mesothelioma (MM) has not been described. This study used enzyme-linked immunoassay (ELISA) to measure 90K in pleural effusions (PEs) and sera from patients with MM (n=28), lung cancer (LC) (n=14) and benign pleural disease (BPD) (n=15). Immunohistochemistry was used to investigate 90K expression in MM and LC tissue sections. The expression of 90K was further evaluated in vitro by ELISA and western blot analysis of conditioned media and cellular extracts of MM, LC and normal human mesothelial (NHM) cell cultures. Finally, the relationships between 90K expression in MM and patient age and survival were studied. The mean 90K level was significantly higher (p<0.05) in PEs of MM patients (11.0+/-6.6 microg/ml) than in LC (6.1+/-3.2 microg/ml) or BPD (6.2+/-5.0 microg/ml) patients. Immunohistochemistry showed a positive reaction for 90K in MM biopsy sections and positive staining limited to inflammatory infiltrates in LC sections. The level of 90K was significantly higher in cell culture media of MM than of LC or NHM (p<0.001). Bands representing proteins with molecular weight of approximately 90 kDa were detected by western blot in MM cellular extracts. An inverse correlation between PE 90K levels and MM patient age (r=-0.45; p=0.017) and a positive correlation between serum 90K levels and MM patient survival (r=0.62; p=0.006) were detected by linear regression analysis. Kaplan-Meier univariate analysis showed increased survival probability for MM patients with serum 90K level >7.3 microg/ml (log rank, p<0.05). This is the first report in MM of the expression of 90K and of its potential diagnostic and prognostic application.

Vascular endothelial growth factor is an autocrine growth factor in human malignant mesothelioma

Vascular endothelial growth factor (VEGF), a potent mitogen for vascular endothelium, is expressed in malignant pleural mesothelioma (MM). The present report examines the effect of VEGF on MM growth. Four MM cell lines produced significantly higher VEGF levels than normal mesothelial cells (1946+/-14 pg/ml vs. 180+/-17 pg/ml; p<0.001). In addition, MM cells expressed the tyrosine kinase-related VEGF receptors Flt-1 and KDR. Recombinant human VEGF phosphorylated both Flt-1 and KDR and increased proliferation of all four MM cell lines in a dose-dependent fashion. Neutralizing antibodies against either VEGF, Flt-1 or KDR significantly reduced MM cellular proliferation. In addition, expression of VEGF, Flt-1, and KDR was observed in MM biopsies. Moreover, higher VEGF levels were found in the pleural effusions of MM patients than in the effusions of patients with non-malignant pleural disease (1885.7+/-894.9 pg/ml vs. 266.9+/-180.5 pg/ml; p<0.001). Linear regression analysis showed a significant inverse correlation between serum VEGF levels and MM patient survival (r=0.72; p<0.01). No correlation was found between tumour vessel density and either serum (r=0.26; p=0.42) or pleural effusion (r=0.35; p=0.26) VEGF levels. These results indicate that VEGF, via activation of its tyrosine kinase receptors, may be a key regulator of MM growth. In addition, VEGF production could have an impact on patient survival, not only by promoting tumour angiogenesis but also by directly stimulating tumour growth.

Prognostic significance of presence and reduplication of basal lamina in malignant pleural mesothelioma

The prognosis of patients with malignant pleural mesothelioma (MM) is dependent more on tumor extension and differentiation than on therapeutic effects. Reduplication of the basal lamina (RBL) is an ultrastructural feature of some benign and malignant tumors that has been inversely correlated with aggressiveness and was recently described in MM. To investigate whether RBL is important for predicting the survival of patients with MM, transmission electron microscopy was used to identify the presence of basal lamina or RBL in biopsy specimens obtained by thoracoscopy from 35 patients. Cox's regression analysis was used to study the relation of these ultrastructural features to survival. Better outcomes were found for patients whose tumors expressed either basal lamina (HR 0.48; 95% CI, 0.09-2.47) or RBL (HR 0.38; 95% CI 0.12-1.22) compared with the reference category, where basal lamina or RBL was not found. The expression of basal lamina and RBL is an important novel prognostic factors in MM. HUM PATHOL 31:1341-1345.

Simian virus-40 sequences are a negative prognostic cofactor in patients with malignant pleural mesothelioma

Several biochemical and clinical factors have been shown to correlate with survival in human malignant pleural mesothelioma (MM). Nevertheless, average survival of 4 to 10 months from diagnosis is sometimes not sufficient for full expression of these factors. Several studies have reported SV40 sequences in MM, suggesting a possible pathogenic role. We investigated whether the presence of these sequences had any effect on MM patient survival. For this study, we used polymerase chain reaction and Southern blot analysis to search for and identify SV40 DNA in biopsy samples from 83 MM patients. These cases were divided according to histology: 62/83 (74. 7%) had epithelioid morphology (EMM) and 21/83 (25.3%) had either biphasic or sarcomatous morphology (B/SMM). SV40 positivity was significantly associated with B/SMM growth pattern (chi-squared test = 5.03, P = 0.025). Kaplan-Meier univariate analysis confirmed the independent effect of histology on MM survival (log-rank test = 13.9, P < 0.001) and showed a trend for increased survival in SV40-negative patients (log-rank test = 2.83, P = 0.09). Most importantly, Cox's regression model showed that SV40-positive status affected the predictive value of histology on patient survival. In particular, when SV40 expression was added to the B/SMM histotype, Cox's regression model showed a significant increase in hazard ratio (HR) with respect to SV40-negative B/SMM (HR = 4.25, 95% CI = 2.00-9. 00, likelihood ratio test = 14.31, P < 0.001). We conclude that SV40 expression is significantly associated with B/SMM histology and represents an important prognostic cofactor when associated with the tumor subtype in MM patients.

Basal lamina reduplication in malignant epithelioid pleural mesothelioma

Malignant mesothelioma of the pleura is divided in three morphological variants: epithelioid, sarcomatous, and biphasic. Histological similarities between epithelioid malignant mesothelioma (EMM) and lung adenocarcinoma are responsible for the difficult differential diagnosis. Monoclonal antibodies are useful for distinguishing the two neoplasms through immunohistochemical phenotyping, although many cases require ultrastructural characterization for definitive diagnosis. In this study, transmission electron microscopic observations of EMM were compared with those of peripheral adenocarcinoma of the lung (PAL). More specifically, the morphology of the basal lamina is described in 23 cases of EMM and 12 cases of PAL. Reduplication of the basal lamina (RBL) was found in 11 cases (48%) of EMM and in none of the PAL cases. The same cases were immunostained for type IV collagen and the localization of this basement membrane component corresponded to the areas where basal lamina was observed. Since RBL has been associated with neoplastic differentiation in other tumors, this novel feature in EMM needs to be evaluated in future prognostic studies in malignant mesothelioma of the pleura. Moreover, RBL expression in EMM may be an additional ultrastructural parameter used in the differential diagnosis between EMM and adenocarcinoma.

SV40 expression in human neoplastic and non-neoplastic tissues: perspectives on diagnosis, prognosis and therapy of human malignant mesothelioma

We have recently demonstrated the association of SV40 and human pleural malignant mesothelioma. Here, we have investigated whether SV40 viral sequences may be associated with other human tumours or other non-neoplastic pathology and whether SV40 DNA or protein expression may be of diagnostic, prognostic or therapeutic relevance. DNA was extracted from paraffin embedded tissues. SV40, JC and BK viral sequences were detected by the polymerase chain reaction and molecular hybridization with specific probes. The screening with three different sets of SV40-related primers demonstrated that 7/18 (38.8%) mesothelioma specimens were SV40 positive as well as 5/18 (27.7%) tubercular pleural lesions. None of the 18 lung cancers, nor the 20 pleural non-specific inflammatory specimens tested were positive. Twenty-five blood samples and 18 urinary sediments from MM patients were also negative. We have also found that SV40 Tag proteins are present in mesothelioma cells and tumours. Tag proteins may interfere with tumour suppressor gene products, such as p53. Preliminary results suggest that wild type p53 transgene expression, obtained after infection with recombinant adenovirus (AdCMV.p53), inhibited in vitro and in vivo proliferation, inducing apoptosis of mesothelioma cells. Infections with control viruses were ineffective. Thus, SV40 DNA and Tag expression in mesothelioma tumour cells, though probably not relevant for diagnostic or prognostic purposes, may be crucial for innovative gene therapy strategies.

[Not Available]

An open, multicenter non-comparative study was carried out in 8 centres in Italy to evaluate the efficacy, safety and tolerability of cefixime (Suprax - Lederle), a third generation oral cephalosporin administered once daily to patients affected by exacerbation of chronic bronchitis. All patients, 124 males and 21 females, aged between 50 and 85, were treated with Suprax at the dose of 400 mg/day for a mean period of 7.4 days. Clinical and laboratory examinations were performed at: T0 (beginning of treatment), T1 (3-4 days after the beginning of treatment), T2 (end of treatment). The following signs/symptoms were recorded in order to evaluate the therapeutic efficacy: sputum quality and quantity, cough, dyspnoea, fever, bronchospasm, chest clinical findings. All these signs and symptoms significantly improved (p between < 0.001 and < 0.05; mean improvement for sign, weighted for time of improvement). Bio-humoral parameters were also recorded in order to evaluate potential therapeutic influences. A significant decrease was observed (p < 0.01 Student t test for paired data) in the white blood cell count and the leukocyte formula. The datum regarding the white blood cell count and leukocyte formula is to be considered a primary effect of the treatment, proving its success. A microbiological search for the pathogen responsible for the infectious process was also performed: in 70/145 subjects the responsible pathogen was identified. The micro-organism was eradicate in 66/70 at T2 (94.3%), the difference T0 = T2 is significant. The X-Ray evidence suggesting a chronic bronchitis, was also evaluated in 81 patients. At T2, in 75/81 subjects the X-Ray evidence turned out to be negative, while in 6/81 it remained positive. This difference was statistically significant (p < 0.01 sign test). An overall clinical evaluation showed a therapeutic success in 133/145 treated patients (91.7%). No side effects were observed.

[Anatomo-radiologic definition of minimal interstitial silicosis and diagnostic contribution of high-resolution computerized tomography]

Minimal interstitial silicosis (MIS) is a histologic entity characterized by questionable radiologic findings--i.e., the p/p 0/1 and 1/0 classes of the International Labour Office (ILO) 1980 classification. Thus, the condition may be responsible for borderline radiologic findings ("suspect" phase of pneumoconiosis). In order to test an alternative method to conventional radiology (CR), HRCT was performed on 35 workers exposed to silica and with histologic diagnosis of MIS: HRCT scans were compared with posteroanterior chest radiographs by using the ILO classification. Histology was the gold standard. HRCT identified many more MIS lesions. Moreover, the superiority of HRCT over CR was also proved by its better correlation with pathologic findings. HRCT provided pieces of information which could not always be obtained by means of conventional chest films. Thus, HRCT can be considered the method of choice in MIS before transbronchial lung biopsy.

[Castleman's disease. A clinical case]

Castleman's disease is an uncommon lymph node syndrome. It is usually a lymphoid hamartoma, rarely systemic. We report a case of Castleman's multicentric disease observed in our hospital and review the literature. In this work we review prognosis, follow-up and therapy of 46 multicentric disease reported in the literature.

[Streptococcus mitis endocarditis. Description of a clinical case]

The diagnostic iter of a case of Streptococcus mitis endocarditis is reported. Bacterial endocarditis was diagnosed in a 32-year-old patient following ultrasound cardiography and microbiological tests. The paper stresses the importance of ultrasound cardiography in the diagnosis of bacterial endocarditis.

[Hereditary spherocytosis and splenectomy]

The case of a sixteen year old girl with hereditary spherocytosis, submitted to splenectomy, is presented. After operation the patient had four serious infections; for this reason she is now treated by antibiotic prophylaxis.

Microcirculation in the elderly

Studies on microcirculation in the elderly include observations in the small vessels of the bulbar conjunctiva and of the nailbed with respect to a classification of the findings according to a number of semeiologic criteria (diameter and shape alterations, terminal capillary network, intravascular red cell aggregation). In vascular diseases of the elderly there are typical alterations of the capillaroscopic findings in the bulbar conjunctiva and in the nailbed, particularly in cases of arteriosclerosis, arterial hypertension, diabetic microangiopathy, heart failure, ischemic myocardiopathies. During the treatment with some vasoactive drugs (nicotinic acid and its derivatives, buflomedil, CPD-choline) there are marked modifications of the small conjunctival vessels, with evident dilatations, appearance of collaterals, increased homogeneity of the blood flow, better evidence of the capillary network and reduction of intravascular red cell aggregation.

Determination of serum angiotensin-converting enzyme in sarcoidosis

Serum angiotensin-converting enzyme activity was measured in 72 patients with sarcoidosis and in 50 normal controls by a radiochemical assay. SACE levels were examined with respect to the 'activity' of the disease, based on clinical, radiographic and physiological assessment. SACE activity in 34 patients with clinical sarcoidosis (147 +/- 44.3 nmol/min/ml) was significantly high (p less than 0.001) when compared to that of 38 patients who had recovered from sarcoidosis (113.9 +/- 26.4 nmol/min/ml) and 50 normal subjects (97.8 +/- 21 nmol/min/ml). SACE levels were significantly different (p less than 0.01) between 15 subjects with 'active' disease (173.9 +/- 51.9 nmol/min/ml) and those with 'inactive' disease (126.1 +/- 26.3 nmol/min/ml). It is concluded that there is a strict correlation between SACE levels and 'activity' of sarcoidosis if multiple criteria (clinical, radiographic and physiological) are employed.

[Vasoactive drugs and microcirculation in old age]

Within a series of studies on microcirculation in the aged, the conjunctival vessels were investigated by means of the intravital microscope in the course of intravenous infusion or prolonged administration of various drugs (xanthinol nicotinate, buflomedil, CPD-choline). During and after the treatment a better perfusion of the small conjunctival vessels (terminal capillary network) was observed, as well as the appearance of collaterals and a reduction of intravascular red cell aggregation. On the basis of these results a further direct demonstration of the vasoactive effect of the drugs under study could be given.

[Microcirculation in the conjunctiva and the nail bed in the aged. Symptomatic and clinico-pharmacologic aspects]

Study of the microcirculation primarily involves assessment of the capillaroscopic findings. In the clinical field, these are mainly obtained from small vessels of the conjunctiva and nail bed. In more recent years, microcirculation has been accompanied as a subject of examination by haemorheology. The study of blood viscosity and red cell deformability is the most promising from the practical standpoint. In the diagnostic and physiopathological evaluation of capillaroscopic findings, importance is attached to differentiation of arterial and venous vessels, the size, shape and configuration of the small vessels, and above all the presence of intravasal red cell clumps. In examination of the nail bed, particular attention is directed to oddities in the shape of the capillary loops, venous stasis and congestion pictures (in decompensated heart disease, for example, and in cor pulmonale), and alterations in the subpapillary plexuses. Examination of the conjunctiva takes account of the presence of tortuous and serpiginous vessels, with pronounced dilatations, as observed in cardiocirculatory decompensation and chronic bronchopulmonary diseases. In arteriosclerosis, tortuosity and dilatation, even as far as the formation of microaneurysms, may be accompanied by the percent of stiff, thin vessels in networks or webs of various sizes. Clinical pharmacology tests, such as those employing vasoactive drugs (xanthinol nicotinate, buflomedyl, cyticholine) are of interest. They result in a marked increase in calibre, with the appearance of collaterals, regression of red cell aggregates, and improved blood flow.

Circulating immune complexes in patients with lung neoplasms

A search was made for circulating immune complexes in 42 patients with biopsy-proven lung cancer; sex- and age-matched healthy volunteers were used as normal controls. Two different mthods were employed: Clq--binding assay and the conglutinin-binding test. Patients and controls were also examined for delayed hypersensitivity by a skin testing using a set of recall antigens. A significant difference was found in the incidence of immune complexes and the response to skin tests between neoplastic subjects and normal controls. However, the incidence of immune complexes was not related to delayed hypersensitivity or the other clinical features investigated.

[Functional study of the pancreatic alpha and beta cells of normal aged subjects, using a standard meal]

Modifications in glycaemic, insulinaemic and pancreatic glucagon levels have been studied in 20 normal elderly subjects and in 20 young adults (controls) following a standard meal. Results showed that glycaemia is higher and insulinaemia rises more slowly in the elderly, while serum glucagon values show no substantial variations in the two groups of subjects.

[Raised glucagon levels of the blood induced by arginine: relation to blood sugar, blood insulin and STH in aged non-diabetics and diabetics]

In a group of aged nondiabetic and diabetic subjects and in a group of young subjects the glycemic, insulin, growth hormone and glucagon response to intravenous arginine was studied. A prompt increase in blood glucose, serum insulin and glucagon levels was observed, but glucose and glucagon peaks were significantly higher in older non diabetic and diabetic subjects. Growth hormone secretion did not show any difference between aged nondiabetic and young subjects, on the contrary it is lower in diabetics. These findings might suggest the hypothesis of the glucose intolerance during old age due to increased release of glucagon.