Accurate excluded-volume corrections to the single-chain static properties of a melt of unentangled polymers

Actual polymer chains cannot cross themselves and each other. However, the popular Rouse model for unentangled polymers considers the chains as being like 'phantoms'. It is shown that excluded volume effects on single-chain statics may be introduced by analytic corrections to the Rouse results. The final expressions do not depend on free parameters. They exhibit excellent agreement with the molecular-dynamics simulations of polymer melts with chain lengths in the range 3≤M≤30. Preliminary results for entangled polymer melts are presented.

Wernicke's encephalopathy in a malnourished surgical patient: clinical features and magnetic resonance imaging

We report a clinical and neuroradiological description of a severe case of Wernicke's encephalopathy in a surgical patient. After colonic surgery for neoplasm, he was treated for a long time with high glucose concentration total parenteral nutrition. In the early post-operative period, the patient showed severe encephalopathy with ataxia, ophthalmoplegia and consciousness disorders. We used magnetic resonance imaging (MRI) to confirm the clinical suspicion of Wernicke's encephalopathy. The radiological feature showed hyperintense lesions which were symmetrically distributed along the bulbo-pontine tegmentum, the tectum of the mid-brain, the periacqueductal grey substance, the hypothalamus and the medial periventricular parts of the thalamus. This progressed to typical Wernicke-Korsakoff syndrome with ataxia and memory and cognitive defects. Thiamine deficiency is a re-emerging problem in non-alcoholic patients and it may develop in surgical patients with risk factors such as malnutrition, prolonged vomiting and long-term high glucose concentration parenteral nutrition.

Molecular dynamics study of the thermal and the density effects on the local and the large-scale motion of polymer melts: scaling properties and dielectric relaxation

Results from a molecular dynamics simulation of a melt of unentangled polymers are presented. The translational motion, the large-scale and the local reorientation processes of the chains, as well as their relations with the so-called "normal" and "segmental" dielectric relaxation modes are thoroughly investigated in wide temperature and pressure ranges. The thermodynamic states are well fitted by the phenomenological Tait equation of state. A global time-temperature-pressure superposition principle of both the translational and the rotational dynamics is evidenced. The scaling is more robust than the usual Rouse model. The latter provides insight but accurate comparison with the simulation calls for modifications to account for both the local chain stiffness and the nonexponential relaxation. The study addresses the issue whether the temperature or the density is a dominant control parameter of the dynamics or the two quantities give rise to comparable effects. By examining the ratio /alphatau//alphaP between the isochronic and isobaric expansivities, one finds that the temperature is dominant when the dynamics is fast. If the relaxation slows down, the fluctuations of the free volume increase their role and become comparable to those of the thermal energy. Detectable cross-correlation between the "normal-mode" and the "segmental" dielectric relaxations is found and contrasted with the usual assumption of independent modes.

Randomized comparison of loops for transurethral resection of the prostate: preliminary results

PURPOSE

To evaluate the comparative efficacy and morbidity of standard transurethral resection of prostate (TURP) and transurethral vaporesection (TUVRP) using four types of loops.

PATIENTS AND METHODS

In a one-to-one randomized study, 50 patients with lower urinary-tract symptoms suggestive of bladder outlet obstruction and benign prostatic enlargement underwent TURP. Clinical data were collected using digital rectal examination, transrectal ultrasonography for evaluation of prostate volume, IPSS and IIEF-5 questionnaires, and serum prostate specific antigen concentrations. Intraoperative blood loss and fluid absorption were evaluated by measuring serum hemoglobin and respiratory alcohol concentration. Patients were followed at 3 and 18 months with evaluation of clinical symptoms, flow rates, residual urine volumes, and complications.

RESULTS

There were no significant differences in blood loss, intraoperative fluid absorption, procedure time, or weight of the resected tissue between standard TURP and TUVRP with the various loops. No significant complications (infections, urethral stricture, reintervention) were seen.

CONCLUSIONS

In this comparison of the clinical outcome and morbidity of standard TURP versus different loops for TUVRP, there were no significant differences in any of the parameters evaluated.

Role of the density in the crossover region of o-terphenyl and poly(vinyl acetate)

The coupling between the reorientation of molecular probes and the density in one low-molar mass glass former [ o -terphenyl (OTP)] and one polymer [poly(vinyl acetate) (PVAc)] is studied in the Goldstein's crossover region where the structural (alpha) and the secondary (beta) relaxations bifurcate. The coupling is found to be strong in OTP and virtually absent in PVAc. The probes sense both the alpha and beta relaxations, and locate their splitting accurately. It is concluded that the density affects the relaxation occurring in the crossover region of OTP but not of PVAc at subnanometer length scales. The findings are compared with recent assessments of the role of the molecular packing close and above the glass transition temperature T(g).

Modifications of plasma concentrations of hormonal and tissue factors during mechanical ventilation with positive end-expiratory pressure

AIM

The aim of this study is to analyse if the decrease of cardiac performance due to positive end-expiratory pressure (PEEP) application, within low values applied in clinical practice (5 cm H(2)O) is able to trigger a response of the main endogenous factors which control and maintain the mean arterial pressure (MAP).

METHODS

This study was applied to 18 patients, admitted to the Intensive Care Unit (ICU) of the University Hospital of Modena, who underwent oro-tracheal intubation and mechanical ventilation. On admission, patients did not suffer from cardiac or lung disease. This study analyses plasma concentrations of epinephrine, norepinephrine, ET-1, NO metabolites, renin, aldosterone at 4 different times: before PEEP application, 60 minutes after the beginning of mechanical ventilation with PEEP, and respectively 30 and 60 minutes after withdrawal of PEEP. At the same time, MAP values and heart rate (HR) have been observed.

RESULTS

Results show an increase of epinephrine and norepinephrine after PEEP application and a decrease to basal values at PEEP withdrawal. All variations are statistically significant. After PEEP introduction, ET-1 showed an increased concentration, although it was not statistically significant, while a significant decreasing trend was observed after PEEP withdrawal. A significant increase of NO metabolite values has been observed together with the increase of ET-1, followed by a decrease to basal values after the withdrawal of PEEP. Concentrations of renin increased when PEEP was applied even though they were not significant and decreased significantly when PEEP was withdrawn. A similar trend was revealed by aldosterone even though it underwent constant significant variations.

CONCLUSION

The administration of PEEP produces an effective response of endogenous substances whose function is to maintain a proper tissue perfusion.

Quality of Life after Cistectomy

We have considered the aspects and the differences of quality of life and erectile function of 32 consecutive patients underwent to surgical operation of radical cistectomy and urinary diversion (11 patients with ileoureteralcutanous sec. Bricker and 21 patients with orthotopic neobladder). Medical Outcomes Study - Short Form - SF36 TEST and International Index of Erectile Function - IIEF-5, TEST have been administered to the patients, to know the Quality of Life assessment and the erectile dysfunction. The evaluation and analysis of the answers show no statistical significant differences between the two groups of patients about quality of life and sexual aspects.

Myocardial perfusion scintigraphy and coronary disease risk factors in systemic lupus erythematosus

OBJECTIVE

To evaluate the prevalence of myocardial perfusion abnormalities and the possible association between myocardial perfusion defects and traditional coronary artery disease (CAD) risk factors as well as systemic lupus erythematosus (SLE) related risk factors.

PATIENTS AND METHODS

Female patients with SLE, disease duration >5 years, age 18-55 years, who had used steroids for at least one year were enrolled. Traditional CAD risk factors evaluated were arterial hypertension, diabetes mellitus, dyslipidaemia, postmenopausal status, smoking, obesity, and premature family CAD profile. Myocardial perfusion scintigraphy was evaluated by single photon emission computed tomography with technetium 99m-sestamibi at rest and after dipyridamole induced stress.

RESULTS

Eight two female patients with SLE without angina pectoris with mean (SD) age 37 (10) years, disease duration 127 (57) months, SLE Disease Activity Index (SLEDAI) score 6 (5), and SLICC/ACR-DI score 2 (2) were evaluated. Myocardial perfusion abnormalities were found in 23 patients (28%). The mean (SD) number of CAD risk factors was 2.2 (1.6). There was a significant positive correlation between age and number of CAD risk factors. Lower high density lipoprotein (HDL) cholesterol level showed a significant association with abnormal scintigraphy. Logistic regression analysis showed that lower HDL cholesterol level and diabetes mellitus were associated with myocardial perfusion abnormalities. Current vasculitis was also associated with abnormal scintigraphy.

CONCLUSIONS

Lower HDL cholesterol level and diabetes mellitus have a significant influence on abnormal myocardial perfusion results found in asymptomatic patients with SLE. Current vasculitis was associated with abnormal myocardial scintigraphy. These data suggest that abnormal myocardial scintigraphy may be related to subclinical atherosclerosis.

High frequency surgery in the treatment of turbinate hypertrophy: 11 years' experience

For over a century, surgical management of lower turbinate hypertrophy has given rise to much discussion. Aim of the present investigation was to establish, by means of the analysis of a large patient population, the efficacy and reproducibility of high frequency surgery in the treatment of this condition. A total of 1689 non-allergic patients with nasal obstruction, presenting hypertrophy of the lower turbinates, were submitted, under local anaesthesia, to turbinates decongestion using a high frequency instrumental unit with a bipolar terminal electrode. Efficacy of the procedure was evaluated on the basis of objective examination, results of questionnaires, active anterior rhinomanometry and mucociliar transport time. Results revealed a reduction of hypertrophy, an improvement in symptoms, a reduction in nasal resistances and an improvement of mucociliar transport time. The large patient population, low post-operative complication rate and the good patient compliance, due also to the fact that no haemostatic procedure is necessary, would suggest that this method is particularly valid, effective and safe for the treatment of hypertrophy of the lower turbinates.

Coronary artery angiography in systemic lupus erythematosus patients with abnormal myocardial perfusion scintigraphy

OBJECTIVE

According to published studies, 16-82% of systemic lupus erythematosus (SLE) patients have abnormal findings on myocardial perfusion tests, but it has not been established whether these patients also have abnormal findings on coronary angiography. The aim of this study was to evaluate the frequency of abnormal findings on coronary angiography in SLE patients in whom myocardial perfusion scintigraphy revealed abnormalities.

METHODS

Ninety female SLE patients (ages 20-55 years, disease duration >5 years, and current or previous steroid treatment for >/=1 year) underwent myocardial perfusion scintigraphy with single-photon-emission computed tomography using (99m)Tc-sestamibi. Images were taken while the patient was at rest and after dipyridamole-induced stress. Myocardial perfusion defects were identified in 30 patients (33%). Twenty-one of these patients (mean +/- SD age 42 +/- 9; mean +/- SD disease duration 132 +/- 66 months) agreed to undergo coronary angiography.

RESULTS

Atherosclerotic plaques were identified by angiography in 8 of the 21 patients (38%). The majority of coronary abnormalities were localized in the anterior descending artery. The mean +/- SD number of risk factors for coronary artery disease (CAD) was significantly higher in the subgroup with (4.5 +/- 0.8) compared with the subgroup without (2.5 +/- 1.9) abnormal angiographic findings (P = 0.006). Arterial hypertension and postmenopause status were significantly associated with abnormal angiographic findings. Of the patients with at least 4 risk factors for CAD, coronary stenosis was present in 67% (P = 0.005). The number of American College of Rheumatology (ACR) criteria for SLE and scores on the SLE Disease Activity Index and the Systemic Lupus International Collaborating Clinics/ACR damage index were also higher in the subgroup with coronary stenosis (P < 0.05).

CONCLUSION

This is the first study to examine coronary angiography results in SLE patients with abnormal findings on myocardial scintigraphy. Our data suggest that myocardial scintigraphy can be used to screen SLE patients and that all patients with abnormal findings plus at least 4 risk factors for CAD should undergo coronary angiography.

Cognitive performance, SPECT, and blood viscosity in elderly non-demented people using Ginkgo biloba

The aging process is associated with several cognitive alterations. This study looks at the effects of taking dried extract of Ginkgo biloba, which has been used in several countries in an attempt to minimize these effects. The subjects were 48 men aged 60 - 70 matched between control and experimental groups for educational level. Evaluation was based on a number of neuropsychological tests in an attempt to cover the largest possible number of functions including Single Photon Emission Computer Tomography (SPECT) and measures of blood viscosity. The study was run on a double-blind basis with placebo and Ginkgo biloba groups evaluated over a period of 8 months. After treatment, the experimental group showed a reduction in blood viscosity, improved cerebral perfusion in specific areas and improved global cognitive functioning. The control group showed the opposite - higher blood viscosity, a reduction in cerebral perfusion (in specific areas), and cognitive deterioration in different functions. Although the mechanisms by which Ginkgo biloba may contribute to overall enhancement of the parameters evaluated have not been specified, this plant extract certainly appears to be effective in the treatment of cognitive deficits in older people. Further research into its use is called for on the basis of the results obtained here.

Sludge dewatering using macrophytes in a small wastewater treatment system: a case study of a pilot scale plant in northern Italy

A study was conducted on a system consisting of two beds of 12 m2 each, planted with reeds and filled with sludge from an activated sludge plant dimensioned for 3000 p.e. During 2001, 10 kg of TS/m2 were loaded in each bed using sludge with a dry matter content of 3% during winter and of 0.5% in summer. The aim of the study was to evaluate parameters such as: COD, TSS, P-PO4(3-), N-NO2-, N-NO3-, N-NH4+ in percolation water, the dewatering capability of the two beds and to estimate N mass balance. The observations on dewatering process showed that dried sludge reached a content of 23% TS in winter and of 30% TS in summer. During summertime the plant did not release any percolation flow; in the rest of the year the concentrations of COD, TSS, P-PO4(3-), N-NO2-, N-NH4- remained within bounds of the European directive (91/271/CEE). The N mass balance proved that 90% of N was removed by the denitrification process.

Brain SPECT imaging in Sydenham's chorea

The objective of the present study was to determine whether brain single-photon emission computed tomography (SPECT) imaging is capable of detecting perfusional abnormalities. Ten Sydenham's chorea (SC) patients, eight females and two males, 8 to 25 years of age (mean 13.4), with a clinical diagnosis of SC were submitted to brain SPECT imaging. We used HMPAO labeled with technetium-99m at a dose of 740 MBq. Six examinations revealed hyperperfusion of the basal ganglia, while the remaining four were normal. The six patients with abnormal results were females and their data were not correlated with severity of symptoms. Patients with abnormal brain SPECT had a more recent onset of symptoms (mean of 49 days) compared to those with normal SPECT (mean of 85 days) but this difference did not reach statistical significance. Brain SPECT can be a helpful method to determine abnormalities of the basal ganglia in SC patients but further studies on a larger number of patients are needed in order to detect the phase of the disease during which the examination is more sensitive.

[Interstitial laser therapy in benign prostatic hyperplasia]

The interstitial laser therapy is a low invasivity system for prostatic benign hyperplasia. We report our experience with Indigo 830e new system where diode laser and optical temperature sensor warrant a laser-induced interstitial thermal therapy able to continuously adjust energy delivery to the tissue.

One shot: a novel method to dilate the nephrostomy access for percutaneous lithotripsy

BACKGROUND AND PURPOSE

The creation of the nephrostomy access is a fundamental step of percutaneous nephrolithotripsy (PCNL). Dilation of the track is usually achieved with multiple incremental flexible exchange dilators of the Amplatz type, metal telescoping dilators of the Alken type, or a balloon. Currently, balloon dilation is regarded as the most modern and safest system, though it has the disadvantage of relatively high cost. The aim of this study was to demonstrate that a procedure that we named "one shot," which consists of a single dilation of the track with a 25F or 30F Amplatz dilator, compares favorably in terms of efficacy, costs, and length with the other techniques of track dilation, without a significant increase in morbidity.

PATIENTS AND METHODS

Seventy-eight consecutive patients who underwent PCNL for stone disease from June 1998 to July 1999 were considered and divided into three groups according to the type of tract dilation used: A (Alken telescoping dilators), B (balloon), or C (one shot). Radiologic exposure, blood loss, and costs were evaluated.

RESULTS

The one-shot procedure compared favorably with both of the other dilation techniques without an increase in morbidity and with significant reductions in X-ray exposure and costs. Indeed, significant differences in estimated blood loss were observed between groups B and C and the minor bleeding for group C.

CONCLUSION

Our experience indicates that one-shot dilation is feasible in the majority of patients. It is as safe and effective as the technique regarded today as the gold standard but less time consuming and less expensive. These encouraging results should be confirmed by further studies.

Biomonitoring of exposure to nitrous oxide, sevoflurane, isoflurane and halothane by automated GC/MS headspace urinalysis

OBJECTIVES

The goal of the present study was to develop an automated method to assess by biological monitoring, the volatile-anaesthetic exposure (nitrous oxide, sevoflurane, isoflurane and halothane) in operating theatre personnel.

METHODS

Post-shift urine samples were analysed by gas chromatography-mass spectrometry coupled with static headspace sampling (GC-MS/ HSS); intra-assay %-RSD (n= 10) was less than 5% for nitrous oxide and less than 7% for each halogenated vapour. The biomonitoring method was validated with air monitoring data, obtained by personal samplers and a similar GC-MS method. The sensitivity achieved by single ion monitoring (SIM) was sufficient to reveal low biological and environmental exposure averages down to 1 microg/l(urine) and 0.5 ppm for nitrous oxide and 0.1 microg/l(urine) and 50 ppb for halogenated compounds, respectively.

RESULTS

In 1998 we collected and analysed 714 post-shift urine samples for the biological monitoring of volatile anaesthetics in the urine of the operating-theatre personnel of Sant'Orsola-Malpighi Hospital (Bologna, Italy). Our data showed that nitrous oxide (N20), the anaesthetic most largely used in general anaesthesia, is still the decisive factor in operating-theatre pollution. Moreover, on the basis of our results, working in close contact with anaesthetics seems to be the main determinant of risk: surgical nurses and anaesthesiologists are the most-exposed professional categories (mean post-shift urinary N2O approximately 65 microg/l(urine)) while general theatre staff, surgeons, and auxiliary personnel have significantly lower exposure.

CONCLUSIONS

The biological monitoring of post-shift unmodified urinary volatile anaesthetics was confirmed to be a useful tool for evaluating individual exposure to these chemicals. The urinary concentrations of N2O and of halogenated vapours might reflect, to a certain extent, the external exposure to these compounds, and respiratory air-monitoring data support the validity of biological monitoring. Furthermore, the good relationship between air and urinary concentration of anaesthetics in people working in closer contact with these chemicals may be a good indirect means of revealing the bad air conditions of operating rooms, and may contribute to the highlighting and correction of service defects in anaesthesiology equipment and of human errors.

Antioxidant activity of carbocysteine lysine salt monohydrate

BACKGROUND

Reactive oxygen radicals are involved in many respiratory diseases, including chronic obstructive pulmonary disease (COPD). Carbocysteine lysine salt monohydrate (CLS) is a mucoactive drug effective in the treatment of bronchopulmonary diseases characterized by mucus alterations, including COPD. In the present study, the antioxidant activity of CLS was studied in vitro in three different oxygen radical producing systems, i.e. bronchoalveolar lavages (BAL) from patients affected by COPD, ultrasound treated human serum and cultured human lung endothelial cells challenged with elastase.

METHODS

BAL, exposed or not to different concentrations of CLS (1.5-30 mM), was assayed for free radical content by fluorometric analysis of DNA unwinding (FADU) or by cytochrome c reduction kinetics. Human serum was treated with ultrasound in the presence or absence of CLS (1.5, 2.5 mM) or N-acetyl cysteine (NAC; 4, 5 mM) and assayed for free radical content by FADU. Human endothelial cells cultured in vitro from pulmonary artery were incubated with elastase (0.3 IU/mL), in the presence or absence of glutathione (GSH; 0.65 mM) or CLS (0.16 mM). The supernatant was tested for cytochrome c reduction kinetics whereas cell homogenates were assessed for xanthine oxidase (XO) content by SDS-PAGE.

RESULTS

Results showed that CLS is more effective as an in vitro scavenger in comparison to GSH and NAC. CLS reduced the damage of DNA from healthy donors exposed to COPD-BAL and was able to quench clastogenic activity induced in human serum by exposure to ultrasound at concentrations as low as 2.5 mM. NAC protect DNA from radical damage, starting from 5 mM. In human lung endothelial cells cultured in presence of elastase, CLS (0.16 mM) decreased xanthine oxidase activity.

CONCLUSIONS

These results suggest that CLS could act by interfering with the conversion of xanthine dehydrogenase into superoxide-producing xanthine oxidase. The antioxidant activity of CLS could contribute to its therapeutic activity by reducing radical damage to different lung structures.

Failure of urinary trans,trans-muconic acid as a biomarker for indoor environmental benzene exposure at PPB levels

Benzene is a widespread pollutant whose main source in the environment is automotive emission. There is increasing interest in the exposure of the population to this pollutant as benzene is present also in the indoor environment due to cigarette smoke, drinking water, and food. The aim of this study was to evaluate, in an adult nonsmoking population not occupationally exposed to benzene, whether it is possible to detect differences in the urinary concentration of trans,trans-muconic acid (t,t-MA) between low and high environmental exposure to benzene. A study sample of 31 employees working in pharmacies in a large town in Italy with low environmental exposure to benzene (4.8 microg/m3) was compared to a high (8.1 microg/m3) benzene exposure group. Analysis of urinary t,t-MA was carried out by high-performance liquid chromatography (HPLC; photodiode array detector); analysis of environmental benzene samples was by gas chromatography/mass spectroscopy (GC-MS). The statistical analysis revealed no significant differences in urinary levels of t,t-MA of subjects with high (mean concentration: 157.9 microg/g creatinine) versus low exposure (mean concentration: 114.2 microg/g creatinine). Data show that it is difficult to correlate urinary t,t-MA with benzene exposure at parts per billion levels.

A rapid and sensitive method for methyl tert-butyl ether analysis in water samples by use of solid phase microextraction and gas chromatography-mass spectrometry

This work describes a rapid and sensitive solid-phase microextraction (SPME) method for the isolation and analysis of methyl tert-butyl ether in water samples. Methyl tert-butyl ether was extracted from aqueous solutions using SPME fibre coated with Divinylbenzene/Carboxen/polydimethylsiloxane (30 microm film thickness) and analysed by GC-MS with a Hewlett Packard 6890/5973 system equipped with a capillary column coated with Vocol (30 m x 0.25 mm, 1.5 microm film thickness). Extraction parameters and chromatographic separation conditions were optimised. The developed method showed good analytical performance in terms of precision (RSD between 2% and 8%) and accuracy (mean recovery from 96% to 104%) with a detection limit of 14 ppt. Finally the method was applied to surface, tap and commercial mineral water samples, as well as snow samples collected along a busy road of Bologna town area. The median concentration of methyl tert-butyl ether in all these samples (0.05-0.4 ppb) was well below the maximum aqueous contamination levels in water adopted in the United States (13 ppb).