Open-Cell AlSn6Cu-SiC Composites: Fabrication, Dry-Sliding Wear Behavior, and Machine Learning Methods for Wear Prediction

Open-cell AMMCs are high-strength and lightweight materials with applications in different types of industries. However, one of the main goals in using these materials is to enhance their tribological behavior, which improves their durability and performance under frictional conditions. This study presents an approach for fabricating and predicting the wear behavior of open-cell AlSn6Cu-SiC composites, which are a type of porous AMMCs with improved tribological properties. The composites were fabricated using liquid-state processing, and their tribological properties are investigated by the pin-on-disk method under different loads (50 N and 100 N) and with dry-sliding friction. The microstructure and phase composition of the composites were investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The mass wear and coefficient of friction (COF) of the materials were measured as quantitative indicators of their tribological behavior. The results showed that the open-cell AlSn6Cu-SiC composite had an enhanced tribological behavior compared to the open-cell AlSn6Cu material in terms of mass wear (38% decrease at 50 N and 31% decrease at 100 N) while maintaining the COF at the same level. The COF of the composites was predicted by six different machine learning methods based on the experimental data. The performance of these models was evaluated by various metrics (R2, MSE, RMSE, and MAE) on the validation and test sets. Based on the results, the open-cell AlSn6Cu-SiC composite outperformed the open-cell AlSn6Cu material in terms of mass loss under different loads with similar COF values. The ML models that were used can predict the COF accurately and reliably based on features, but they are affected by data quality and quantity, overfitting or underfitting, and load change.

Lattice distortions and the metal-insulator transition in pure and Ti-substituted Ca3Ru2O7

We report pair distribution function studies on the relationship between the metal-insulator transition (MIT) and lattice distortions in pure and Ti-substituted bilayer Ca₃Ru₂O₇. Structural refinements performed as a function of temperature, magnetic field and length scale reveal the presence of lattice distortions not only within but also orthogonal to the bilayers. Because of the distortions, the local and average crystal structure differ across a broad temperature region extending from room temperature to temperatures below the MIT. The coexistence of distinct lattice distortions is likely to be behind the marked structural flexibility of Ca₃Ru₂O₇under external stimuli. This observation highlights the ubiquity of lattice distortions in an archetypal Mott system and calls for similar studies on other families of strongly correlated materials.

Atomic structure and Mott nature of the insulating charge density wave phase of 1T-TaS2

Using x-ray pair distribution function (PDF) analysis and computer modeling, we explore structure models for the complex charge density wave (CDW) phases of layered 1T-TaS₂that both well capture their atomic-level features and are amenable to electronic structure calculations. The models give the most probable position of constituent atoms in terms of 3D repetitive unit cells comprising a minimum number of Ta-S layers. Structure modeling results confirm the emergence of star-of-David (SD) like clusters of Ta atoms in the high-temperature incommensurate (IC) CDW phase and show that, contrary to the suggestions of recent studies, the low-temperature commensurate (C) CDW phase expands upon cooling thus reducing lattice strain. The C-CDW phase is also found to preserve the stacking sequence of Ta-S layers found in the room temperature, nearly commensurate (NC) CDW phase to a large extent. DFT based on the PDF refined model shows that bulk C-CDW 1T-TaS₂also preserves the insulating state of individual layers of SD clusters, favoring the Mott physics description of the metal-to-insulator (NC-CDW to C-CDW) phase transition in 1T-TaS₂. Our work highlights the importance of using precise crystal structure models in determining the nature of electronic phases in complex materials.

SOCIAL STATUS AND GUT MICROBIAL DYSBIOSIS IN ADULTS AND CHILDREN WITH AUTISM SPECTRUM DISORDERS: A PROFOUND REVIEW OF THE AVAILABLE LITERATURE SOURCES

Autism is a complex disorder without a specific diagnosis, so the disease is defined by its specific characteristics described in the literature as cognitive defects, social, communication and behavioral problems, repetitive behaviors, unusual sensitivity to stimuli such as noise, restricted interests, and self stimulation. There are many models in the literature explaining the biology of autism, which are based on genetics, immunity, various environmental factors and diet. There is a lot of literature data that people with Autism Spectrum Disorders (ASD) often have gastrointestinal problems that also affect their behavior. ASD suffer developmental disabilities from an early age, which can be both physical and psychological. Often people suffer these problems even throughout their lives. This review aims to provide basic information on definitions, historical data, diagnostic methods, behavioral etiology, gastrointestinal and social problems in adults and children with ASD.

Reactive gas environment induced structural modification of noble-transition metal alloy nanoparticles

Noble-transition metal (noble=Pt,Au; transition=Co,Ni,Cu) alloy particles with sizes of about 5 nm have been studied by in situ high-energy x-ray diffraction while subjected to oxidizing (O(2)) and reducing (H(2)) gas atmospheres at elevated temperatures. The different gas atmospheres do not affect substantially the random alloy, face-centered-cubic structure type of the particles but do affect the way the metal atoms pack together. In an O(2) atmosphere, atoms get extra separated from each other, whereas, in an H(2) atmosphere, they come closer together. The effect is substantial, amounting to 0.1 Å difference in the first neighbor atomic distances, and concurs with a dramatic change of the particle catalytic properties. It is argued that such reactive gas induced "expansion shrinking" is a common phenomenon that may be employed for the engineering of "smart" nanoparticles responding advantageously to envisaged gas environments.

Molecular arrangement in water: random but not quite

Water defines life on Earth from the cellular to the terrestrial level. Yet the molecular level arrangement in water is not well understood, posing problems in comprehending its very special chemical, physical and biological properties. Here we present high-resolution x-ray diffraction data for water clearly showing that its molecular arrangement exhibits specific correlations that are consistent with the presence of rings of H(2)O molecules linked together by hydrogen bonds into tetrahedral-like units from a continuous network. This level of molecular arrangement complexity is beyond what a simple 'two-state' model of water (Bernal and Fowler 1933 J. Chem. Phys.1 515-48) could explain. It may not be explained by the recently put forward 'chains-clusters of completely uncorrelated molecules' model (Wernet et al 2004 Science 304 995-9) either. Rather it indicates that water is homogeneous down to the molecular level where different water molecules form tetrahedral units of different perfection and/or participate in rings of different sizes, thus experiencing different local environments. The local diversity of this tetrahedral network coupled to the flexibility of the hydrogen bonds that hold it together may explain well the rich phase diagram of water and why it responds non-uniformly to external stimuli such as, for example, temperature and pressure.

Plasmon-enhanced sub-wavelength laser ablation: plasmonic nanojets

In response to the incident light's electric field, the electron density oscillates in the plasmonic hotspots producing an electric current. Associated Ohmic losses raise the temperature of the material within the plasmonic hotspot above the melting point. A nanojet and nanosphere ejection can then be observed precisely from the plasmonic hotspots.

Hotspot decorations map plasmonic patterns with the resolution of scanning probe techniques

In high definition mapping of the plasmonic patterns on the surfaces of nanostructures, the diffraction limit of light remains an important obstacle. Here we demonstrate that this diffraction limit can be completely circumvented. We show that upon illuminating nanostructures made of nickel and palladium, the resulting surface-plasmon pattern is imprinted on the structures themselves; the hotspots (regions of local field enhancement) are decorated with overgrowths, allowing for their subsequent imaging with scanning-probe techniques. The resulting resolution of plasmon pattern imaging is correspondingly improved.

Melting of Bi sublattice in nanosized BiFeO3 Perovskite by resonant X-ray diffraction

Free-standing BiFeO3 perovskite particles with a size ranging from polycrystalline bulk down to 5 nm have been studied by high-energy resonant (Bi K edge) x-ray diffraction coupled to differential atomic pair distribution function analysis. Nanosized BiFeO3 particles are found to exhibit extra, i.e., beyond the usual thermal, structural disorder that increases progressively with diminishing their size. In particles of size smaller than approximately 18 nm the disorder destroys the structural coherence of the Bi sublattice and disturbs that of the Fe-based sublattice in the perovskite structure, substantially affecting the magnetoelectric properties it carries. The new structural information helps better understand the unusual behavior of perovskites structured at the nanoscale.

Atomic-scale structure of GeSe2 glass revisited: a continuous or broken network of Ge-(Se(1/2))4 tetrahedra?

The atomic-scale structure of germanium diselenide (GeSe(2)) glass has been revisited using a combination of high-energy x-ray diffraction and constrained reverse Monte Carlo simulations. The study shows that the glass structure may be very well described in terms of a continuous network of corner- and edge-sharing Ge-Se(4) tetrahedra. The result is in contrast to other recent studies asserting that the chemical order and, hence, network integrity in GeSe(2) glass are intrinsically broken. It is suggested that more elaborate studies are necessary to resolve the controversy.

[Management of deep device related infection in patient implanted with mechanical cardiac support device using V.A.C. system]

Infection remains the most significant cause of morbidity and mortality in pacients implanted with mechanical circulatory support devices (MCSD), reaching prevalence of 40-60% according various authors. Successful treatment of the whole spectrum of infectious complications is the basic determinant in archieving good results in MCSD patients. The treatment involves standard surgical procedures, as well as the use of vacuum assisted closure (V.A.C.) therapy in the last few years. We demonstrate successful management of deep device related infection using V.A.C therapy in a patient with MCSD, giving him the opportunity to heart transplantation, and thereafter successful treatment of poststernotomy mediastinitis in this imunosupressed pacient after heart transplantation.

Chemical short range order obtained from the atomic pair distribution function

Many crystalline materials show chemical short range order and relaxation of neighboring atoms. Local structural information can be obtained by analyzing the atomic pair distribution function (PDF) obtained from powder diffraction data. In this paper, we present the successful extraction of chemical short range order parameters from the x-ray PDF of a quenched Cu3Au sample.

Atomic-scale structure of biogenic materials by total X-ray diffraction: a study of bacterial and fungal MnOx

Biogenic materials are produced by microorganisms and are typically found in a nanophase state. As such, they are difficult to characterize structurally. In this report, we demonstrate how high-energy X-ray diffraction and atomic pair distribution function analysis can be used to determine the atomic-scale structures of MnO(x) produced by bacteria and fungi. These structures are well-defined, periodic, and species-specific, built of Mn-O(6) octahedra forming birnessite-type layers and todorokite-type tunnels, respectively. The inherent structural diversity of biogenic material may offer opportunities for practical applications.

Pulmonary and systemic effects of inhaled PACAP38 in healthy male subjects

BACKGROUND

Pituitary adenylate cyclase activating polypeptide 1-38 (PACAP38) displays biological activities (e.g. bronchodilatory, pulmonary vasodilatory and anti-inflammatory properties) that are relevant in several pulmonary diseases. The aim of this study was to assess the safety and tolerability and the pulmonary and systemic effects of inhaled PACAP38 in humans.

MATERIALS AND METHODS

Twelve healthy male subjects (mean age 28) were studied in a randomized, double-blind, placebo-controlled dose escalation trial with inhalation of PACAP38 to a cumulative dose of 480 microg. Lung function was measured by body plethysmography. Systemic absorption was evaluated by plasma levels, skin blood flux (estimated by laser Doppler imager fluxmetry) and systemic haemodynamics.

RESULTS

Inhalation of PACAP38 did not cause relevant adverse reactions or an increase of PACAP38 plasma levels. No statistically significant changes in lung function tests and no systemic effects (blood pressure, pulse rate or skin blood flux) occurred.

CONCLUSION

Inhaled PACAP38 was well tolerated without systemic side-effects in healthy male subjects.

Controlled prospective randomised trial on the effects on pulmonary haemodynamics of the ambulatory long term use of nitric oxide and oxygen in patients with severe COPD

BACKGROUND

Pulmonary hypertension is a frequent complication of severe chronic obstructive pulmonary disease (COPD) and a major cause of morbidity and mortality in this condition. Based on the improved survival of these patients due to long term oxygen therapy and the potent and selective pulmonary vasodilation by inhaled nitric oxide, the safety and effectiveness of the combined inhalation of these two gases over a 3 month period was assessed.

METHODS

Forty patients with secondary pulmonary hypertension due to COPD were randomly assigned to receive either oxygen alone or "pulsed" inhalation of nitric oxide with oxygen over a period of 3 months. "Pulsed" inhalation of nitric oxide was used to reduce pulmonary ventilation-perfusion mismatch and formation of toxic reaction products of nitric oxide and oxygen.

RESULTS

Compared with oxygen alone, the combined inhalation of nitric oxide and oxygen caused a significant decrease in mean (SE) pulmonary artery pressure (from 27.6 (4.4) mm Hg to 20.6 (4.9) mm Hg, p<0.001) and pulmonary vascular resistance index (from 569.7 (208.1) to 351.3 (159.9) dyne x s(-1) x cm(-5) x m(-2), p<0.001) without decreasing arterial oxygenation. Cardiac output increased by 0.5 litres (from 5.6 (1.3) l/min to 6.1 (1.0) l/min, p=0.025). Systemic haemodynamics and left heart function remained unchanged during this period and no increase in toxic reaction products of nitric oxide was observed.

CONCLUSIONS

This is the first controlled trial indicating that the "pulsed" inhalation of nitric oxide together with oxygen may be safely and effectively used for the long term treatment of severe COPD.

Structure of intercalated Cs in zeolite ITQ-4: an array of metal ions and correlated electrons confined in a pseudo-1D nanoporous host

The presence of Cs+ ions in the pseudo-1D nanopores of zeolite ITQ-4, Si32O64, is confirmed by x-ray diffraction and atomic pair distribution function analysis. Inside the nanopores the Cs+ ions are found to assemble in zigzag chains and thus form an extended, positively charged sublattice providing charge balance for a low-density electron gas also confined to the nanopores.

[Pathogen resistance and other risk factors in the frequency of lower limb amputations in patients with the diabetic foot syndrome]

Patients with diabetes mellitus undergo more amputations due to peripheral vascular disease, neuropathy and especially to infection requiring long-lasting antibiotic therapy than non diabetic patients. The aim of our study was to assess the association between the presence of resistant pathogens presented in diabetic ulcers and the frequency of lower limb amputations.

METHODS

191 diabetic patients consecutively treated for the diabetic foot in our foot clinic were included into two years retrospective study. Peripheral ischemia, the presence of osteomyelitis and the incidence of all Gram positive and negative resistant pathogens (defined as resistance to all oral antibiotics) especially of resistant Staphylococcus species presenting in diabetic foot ulcers were determined.

RESULTS

50/191 (26%) patients underwent amputation, of whom 44/50 (88%) had minor and 6/50 (12%) had major amputations. 53/181 (29%) patients with diabetic foot ulcers had resistant pathogens in their defects. Amputated patients had significantly more resistant microorganisms than patients without amputations--24/42 (57%) vs. 29/139 (21%); p < 0.001. Resistant Staphylococcus species were found in 21% (38/181) of all patients. Patients with amputations had significantly more resistant Staphylococcus species in comparison with patients without amputations--18/42 (43%) vs. 20/139 (14%); p < 0.001. Significantly higher incidence of peripheral vascular disease--79% (38/48) vs. 60% (81/136); p < 0.05 and osteomyelitis--69% (33/48) vs. 13% (18/140); p < 0.001--were found in patients with amputations in comparison with patients without amputations.

CONCLUSION

The presence of pathogens resistant to all oral antibiotics and especially of resistant Staphylococcus species was significantly higher in diabetic patients with lower limb amputations in comparison with patients without amputations.

Aerosolised iloprost improves pulmonary haemodynamics in patients with primary pulmonary hypertension receiving continuous epoprostenol treatment

BACKGROUND

Continuous intravenous treatment with epoprostenol significantly improves pulmonary haemodynamics and survival in patients with primary pulmonary hypertension (PPH). Its beneficial effect, however, may be blunted due to adverse effects such as catheter sepsis and systemic hypotension. Recent investigations have shown that inhaled iloprost is effective in the treatment of PPH. Based on their different pharmacokinetics, we hypothesised that the combination of intravenous epoprostenol and inhaled iloprost would be more efficacious than epoprostenol alone during acute testing in patients with PPH.

METHODS

The effect of a single dose of inhaled iloprost (30 μg total over 15 minutes) on pulmonary haemodynamics was examined in eight patients with PPH (initial non-responders to nitric oxide) who had considerable adverse effects during treatment with epoprostenol.

RESULTS

The combination of inhaled iloprost and intravenous epoprostenol significantly improved mean pulmonary artery pressure (MPAP), cardiac index (CI), mixed venous oxygen saturation (Svo2), and systemic arterial oxygen pressure (Pao2) compared with epoprostenol treatment alone. Mean systemic arterial pressure (MSAP) and pulmonary capillary wedge pressure (PCWP) remained unchanged.

CONCLUSIONS

The pulmonary vasoreactivity shown by additional iloprost inhalation during effective epoprostenol treatment suggests that an improvement of treatment for pulmonary hypertension may be possible by combining vasoactive substances.

111In-DOTA-lanreotide scintigraphy in patients with tumors of the lung

Imaging with radiolabeled somatostatin (SST) analogs has recently been established for the localization of various human SST receptor (hsstr)-positive tumors, including neuroendocrine tumors, lymphomas, and non-small cell lung cancer (NSCLC).

METHODS

111In-1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid-lanreotide (DOTA-LAN) scintigraphy (150 MBq; 7 nmol per patient) was performed on 47 patients (28 patients with primary tumors, 19 patients with lung metastases from other tumors) to evaluate the tumor binding in patients with histologically confirmed lung cancer. A group of 27 tumor patients without documented lung lesions served as the control group. Early and delayed planar and SPECT images were acquired. Whole-body scintigraphy was performed at 0.5, 4-6, 24, and 48 h after injection for tumor dose estimation. In addition, hsstr subtype expression and radioligand binding characteristics were studied in vitro using lung tumor samples (n = 15).

RESULTS

111In-DOTA-LAN indicated the primary lung tumor in 16 of 16 NSCLC patients. Lymph node metastases were visualized in 6 of 6 NSCLC patients, and bone metastases were seen in 3 of 3 NSCLC patients. 111In-DOTA-LAN scintigraphy indicated lung carcinoid in 5 of 5 patients and small cell lung cancer lesions in 6 of 6 patients. Multiple lung metastases were shown in all 6 patients with non-Hodgkin's lymphoma and in the 1 patient with Hodgkin's disease, 5 of 5 colorectal adenocarcinoma patients, 4 of 4 carcinoid patients, 2 of 2 neuroendocrine carcinoma (NEC) patients, and 1 of 1 angiosarcoma patient. Pulmonary tumor sites not indicated by CT or MRI were visualized in 6 of 47 tumor patients (i.e., 13%; lung metastases in 1 carcinoid patient and 1 NEC patient, lymph node metastases in 1 carcinoid patient and 2 NSCLC patients, bone metastases in 1 carcinoid patient). The estimated lung tumor dose ranged between 0.2 and 5 mGy/MBq. Focal lung uptake of 111In-DOTA-LAN was not observed in any of the 27 control patients. In vitro binding studies indicated high-affinity binding sites for 111In-DOTA-LAN in NSCLC samples (dissociation constants, 0.5 and 4 nmol/L) with predominant expression of hsstr4.

CONCLUSION

111In-DOTA-LAN yields high tumor binding for various human lung tumors. Consecutively, radiopeptide therapy may offer a potential new treatment alternative for some lung tumor patients.

Aerosolised iloprost improves pulmonary haemodynamics in patients with primary pulmonary hypertension receiving continuous epoprostenol treatment

BACKGROUND

Continuous intravenous treatment with epoprostenol significantly improves pulmonary haemodynamics and survival in patients with primary pulmonary hypertension (PPH). Its beneficial effect, however, may be blunted due to adverse effects such as catheter sepsis and systemic hypotension. Recent investigations have shown that inhaled iloprost is effective in the treatment of PPH. Based on their different pharmacokinetics, we hypothesised that the combination of intravenous epoprostenol and inhaled iloprost would be more efficacious than epoprostenol alone during acute testing in patients with PPH.

METHODS

The effect of a single dose of inhaled iloprost (30 microg total over 15 minutes) on pulmonary haemodynamics was examined in eight patients with PPH (initial non-responders to nitric oxide) who had considerable adverse effects during treatment with epoprostenol.

RESULTS

The combination of inhaled iloprost and intravenous epoprostenol significantly improved mean pulmonary artery pressure (MPAP), cardiac index (CI), mixed venous oxygen saturation (SvO2), and systemic arterial oxygen pressure (PaO2) compared with epoprostenol treatment alone. Mean systemic arterial pressure (MSAP) and pulmonary capillary wedge pressure (PCWP) remained unchanged.

CONCLUSIONS

The pulmonary vasoreactivity shown by additional iloprost inhalation during effective epoprostenol treatment suggests that an improvement of treatment for pulmonary hypertension may be possible by combining vasoactive substances.

Long-term treatment of pulmonary hypertension with aerosolized iloprost

Pulmonary arterial hypertension (PAH), defined as elevated pulmonary arterial pressure and pulmonary vascular resistance, is an end-point of a variety of conditions. The only therapy that has been shown to improve both quality of life and survival is intravenous prostacyclin (prostaglandin I2 (PGI2), epoprostenol). The effect of long-term aerosolized iloprost (Ilomedin, Schering, Berlin, Germany and Vienna, Austria), a stable prostacyclin analogue and potent vasodilator, on haemodynamics and functional status was investigated in 12 patients with severe pulmonary hypertension. Haemodynamic measurements and vasodilator testing by right heart catheterization were performed prior to and after long-term iloprost inhalation therapy. Haemodynamic improvement or increased exercise tolerance was not observed in any of the patients. After a mean+/-SD treatment period of 10+/-5 months, mean+/-SD pulmonary vascular resistance had increased from 11+/-3 Wood Units (mmHg.L(-1).min) to 13+/-4 Wood Units, with unchanged arterial oxygen saturation (92+/-4%, versus 91+/-4%). Within the study period, three patients went into right heart failure and had to be placed on intravenous epoprostenol. The authors conclude that inhaled iloprost in addition to conventional therapy in the presently recommended dose of 100 microg.day(-1) delivered in 8-10 2 h portions, is not an efficient vasodilator therapy in severe pulmonary hypertension. It remains to be shown whether dose increases and/or combination protocols will be effective, or whether inhalation of iloprost may be safe for selected cases of pulmonary hypertension.

Aerosolized iloprost therapy could not replace long-term IV epoprostenol (prostacyclin) administration in severe pulmonary hypertension

OBJECTIVES

To switch patients with severe pulmonary hypertension and previous life-threatening catheter-related complications from long-term IV epoprostenol therapy to aerosolized iloprost therapy.

DESIGN

Open, uncontrolled trial.

SETTING

Medical ICU of a university hospital.

PATIENTS

Two patients with primary pulmonary hypertension and one patient with pulmonary hypertension after surgical closure of atrial septal defect (mean pulmonary artery pressure > or =50 mm Hg). All were classified as New York Heart Association class II under treatment with continuous IV epoprostenol for 4 years.

INTERVENTIONS

Stepwise reduction of IV epoprostenol (1 ng/kg/min steps every 3 to 10 h) during repeated inhalations of aerosolized iloprost (150 to 300 microg/d with 6 to 18 inhalations/d). Continuous pulmonary and systemic arterial monitoring were performed.

RESULTS

Aerosolized iloprost reduced pulmonary artery pressure by 49%, 49%, and 45%, respectively, and increased cardiac output by 70%, 75%, and 41% in the three patients. The effect lasted for 20 min and was similar at different doses of IV epoprostenol. Persistent treatment change to inhaled iloprost could not be achieved because all patients developed signs of right heart failure. After termination of iloprost inhalations, return to standard epoprostenol therapy led to clinical and hemodynamic restoration.

CONCLUSIONS

Although aerosolized iloprost demonstrated short-term hemodynamic effects, it could not be utilized as alternative chronic vasodilator in patients with severe pulmonary hypertension.

Polyhedral units and network connectivity in calcium aluminosilicate glasses from high-energy X-Ray diffraction

Structure factors for Ca (x/2)Al xSi 1-xO (2) glasses (x = 0,0.25,0. 5,0.67) extended to a wave vector of magnitude Q = 40 A (-1) have been obtained by high-energy x-ray diffraction. For the first time, it is possible to resolve the contributions of Si-O, Al-O, and Ca-O coordination polyhedra to the experimental atomic pair distribution functions. It has been found that the connectivity of Si/Al-O tetrahedral network decreases with increasing x due to the emerging of nonbridging oxygens located on Si-O tetrahedra. Calcium maintains a rather uniform coordination sphere for all values of x and so it plays a certain role in determining the glass structure.

Treatment with epoprostenol reverts nitric oxide non-responsiveness in patients with primary pulmonary hypertension

OBJECTIVE

To assess whether long term treatment with epoprostenol might restore primary non-responsiveness to nitric oxide (NO) in patients with primary pulmonary hypertension.

METHODS

Seven patients with primary pulmonary hypertension receiving intravenous epoprostenol continuously because of failure of NO to influence pulmonary haemodynamics during initial testing were followed over a period of 13-29 months. Afterwards, acute vascular reactivity towards NO was tested again during right heart catheterisation.

RESULTS

Administration of NO after continuous epoprostenol treatment for a mean period of 18 months improved arterial oxygen saturation (p < 0.01) and cardiac index (p < 0.05), and decreased mean pulmonary artery pressure (p < 0.01) and total pulmonary vascular resistance (p < 0.01) in patients previously unresponsive to NO.

CONCLUSIONS

Long term treatment with epoprostenol reverts initial refractoriness to NO in patients with primary pulmonary hypertension. Thus the addition of NO to epoprostenol treatment might cause further improvement in the course of the disease.

A preliminary study of long-term treatment with interferon gamma-1b and low-dose prednisolone in patients with idiopathic pulmonary fibrosis

BACKGROUND AND METHODS

Patients with idiopathic pulmonary fibrosis have progressive scarring of the lung and usually die within four to five years after symptoms develop. Treatment with oral glucocorticoids is often ineffective. We conducted an open, randomized trial of treatment with a combination of interferon gamma-1b, which has antifibrotic properties, and an oral glucocorticoid. We studied 18 patients with idiopathic pulmonary fibrosis who had not had responses to glucocorticoids or other immunosuppressive agents. Nine patients were treated for 12 months with oral prednisolone alone (7.5 mg daily, which could be increased to 25 to 50 mg daily), and nine with a combination of 200 microg of interferon gamma-1b (given three times per week subcutaneously) and 7.5 mg of prednisolone (given once a day).

RESULTS

All the patients completed the study. Lung function deteriorated in all nine patients in the group given prednisolone alone: total lung capacity decreased from a mean (+/-SD) of 66+/-8 percent of the predicted value at base line to 62+/-6 percent at 12 months. In contrast, in the group receiving interferon gamma-1b plus prednisolone, total lung capacity increased (from 70+/-6 percent of the predicted value at base line to 79+/-12 percent at 12 months, P<0.001 for the difference between the groups). In the group that received interferon gamma-1b plus prednisolone, the partial pressure of arterial oxygen at rest increased from 65+/-9 mm Hg at base line to 76+/-8 mm Hg at 12 months, whereas in the group that received prednisolone alone it decreased from 65+/-6 to 62+/-4 mm Hg (P<0.001 for the difference in the change from baseline values between the two groups); on maximal exertion, the value increased from 55+/-6 to 65+/-8 mm Hg in the group that received combined treatment and decreased from 55+/-6 mm Hg to 52+/-5 mm Hg in the group given prednisolone alone (P<0.001). The side effects of interferon gamma-1b, such as fever, chills, and muscle pain, subsided within the first 9 to 12 weeks.

CONCLUSIONS

In a preliminary study, 12 months of treatment with interferon gamma-1b plus prednisolone was associated with substantial improvements in the condition of patients with idiopathic pulmonary fibrosis who had had no response to glucocorticoids.

Positron emission tomography with fluorine-18-2-fluoro-2-deoxy-D-glucose (F18-FDG) does not visualize extranodal B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT)-type

BACKGROUND

On the basis of promising data on the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (F18-FDG) whole body positron emission tomography (WB-FDG-PET) in the staging of patients with lymphoma, we initiated a pilot series to evaluate the role of WB-FDG-PET in the staging of extranodal B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) type.

PATIENTS AND METHODS

We examined ten consecutive patients with histologically-verified MALT-type lymphomas of various origin before initiation of therapy. Nine patients had low-grade lymphomas (five cases of gastric lymphoma, two patients with lymphoma arising in the lung, one parotid and one lacrimal gland lymphoma), while one patient had a high-grade gastric lymphoma arising from a low-grade background. Two patients had stage EI, seven had stage EII disease, and one presented with stage EIII. WB-FDG-PET scans were performed 40 min following the injection of 300-380 MBq of F18-FDG. The PET scans were correlated with extensive conventional staging including ophthalmologic investigation, otolaryngologic examination, gastroscopy, endosonography, enteroclysis, colonoscopy, CT of thorax and abdomen, and bone marrow biopsy.

RESULTS

WB-FDG-PET documented no lymphoma in any of the 10 patients studied, as no focal tracer uptake was demonstrated in either gastric or extragastric lesions or in involved lymph nodes, irrespective of histologic grading. In three patients the scan showed a false negative result with respect to the MALT lesions but showed focal tracer uptake indicating tumor spread, which, however, was ruled out by further follow-up and biopsy, respectively, and was thus rated false positive. Due to these results, the study was discontinued prematurely after the first ten patients.

CONCLUSIONS

These discouraging results indicated that WB-FDG-PET is not useful for staging and follow-up of MALT-type lymphoma, and should therefore not be included in the clinical decision making process.

Structure of ZrO2SiO2 Gels

xZrO2(1 − x)SiO2 gels have been prepared by hydrolytic polycondensation of tetraethylorthosilicate and zirconium n-propoxide in alcohol solution (x = 0.1–0.5). The formation of the gels has been investigated in situ by conventional small-angle X-ray scattering. (SAXS) experiments. Primary particles of size 1–2 nm have been found in all hydrogels at the first stage of the gelation process. With further progress of the gelation, the primary particles have been found to aggregate into secondary clusters with fractal characteristics. It has also been observed that the higher the Zr concentration in the sol the faster the rate of aggregation of the primary particles. Anomalous small-angle X-ray scattering (ASAXS) and wide-angle X-ray scattering (WAXS) experiments have also been carried out on samples of ZrO2–SiO2 xerogels that have been dried only and samples that have been further heat-treated at various temperatures. The ASAXS experiments have shown that the xerogels obtained without manipulating the aggregation rate do not exhibit microinhomogeneities even when heated up to 800 K. Reverse Monte Carlo simulations based on the experimental wide-angle diffraction data have also been carried out. In line with the findings of the ASAXS experiments, the simulations have suggested that Zr and Si atomic species in the ZrO2–SiO2 xerogels investigated are homogeneously distributed at the atomic scale. The first traces of a phase segregation into Si- and Zr-rich phases, as demonstrated by the emergence of tetragonal ZrO2, were detected only after prolonged heat treatment at 1100 K.

Lipopolysaccharide and interleukin 1 augment the effects of hypoxia and inflammation in human pulmonary arterial tissue

The combined effects of hypoxia and interleukin 1, lipopolysaccharide, or tumor necrosis factor alpha on the expression of genes encoding endothelial constitutive and inducible nitric oxide synthases, endothelin 1, interleukin 6, and interleukin 8 were investigated in human primary pulmonary endothelial cells and whole pulmonary artery organoid cultures. Hypoxia decreased the expression of constitutive endothelial nitric oxide synthase (NOS-3) mRNA and NOS-3 protein as compared with normoxic conditions. The inhibition of expression of NOS-3 corresponded with a reduced production of NO. A combination of hypoxia with bacterial lipopolysaccharide, interleukin 1 beta, or tumor necrosis factor alpha augmented both effects. In contrast, the combination of hypoxia and the inflammatory mediators superinduced the expression of endothelin 1, interleukin 6, and interleukin 8. Here, we have shown that inflammatory mediators aggravate the effect of hypoxia on the down-regulation of NOS-3 and increase the expression of proinflammatory cytokines in human pulmonary endothelial cells and whole pulmonary artery organoid cultures.

Characteristic features of HIV/AIDS in the Czech Republic

First laboratory proved HIV infections in the Czech Republic were diagnosed in a homosexual couple in autumn of 1985. Total number of detected HIV+ cases reached 143 persons by the end of 1992 (132 men and 11 women), of that 31 cases were classified as fully blown AIDS (21 already died). Out of these 143 HIV+ cases, 93 (65.0%) are represented by homo/bisexuals, 10 (7.0%) by heterosexuals, 16 (11.2%) by haemophiliacs, 14 (9.8%) by blood recipients, 1 (0.7%) by IVDU and 9 (6.3%) by unknown transmission category. Approx. 2.1 mil. of tests have been done as routine screening of donated blood. Only 5 cases (0.0002%) of HIV positivity have been found in this group. All HIV positive blood recipients (30 cases) were infected before the mandatory HIV testing of blood supply has been introduced in 1987 (14 out of 16 HIV+ haemophiliacs were infected by imported clotting products). The twins born in 1990 to mother infected by contaminated blood in 1984, were declared at the age of 30 months as HIV free, with all laboratory tests (serology, virus cultivation, PCR) negative. The cummulative infection rate of HIV antibody in 1986-1992 reached 13.8 per million inhabitants. It may be concluded that slow steady increase in the number of reported HIV/AIDS cases has been registered during the whole follow-up period. The authors are aware that relatively low prevalence of HIV infection in the Czech Republic may change dramatically in consequences of recent deep social, political and economical changes in the country.

[Cultivation of HIV-1 virus on mononuclear peripheral blood cells of HIV-1 seropositive individuals]

Using the method of co-cultivation with phytohaemagglutinin-stimulated lymphocytes from healthy donors, the author isolated the HIV-1 virus from peripheral mononuclear blood cells of three patients with the AIDS symptomatology and one patient with the ARC symptomatology. The presence of the virus in infected cells was proved by detection of the viral antigen p 24 in enzymatic immunoassays and in the immunofluorescence test. Three of the isolated strains were adapted to sensitive continual tissue cultures, where the isolates caused chronic infection of the cells associated with the development of a cytopathic effect. In the investigated patients no relationship was proved between viraemia and antigenaemia. The author discusses the importance of virus cultivation for laboratory diagnosis, epidemiology and research of HIV infection and AIDS.

FIT, a computer program for decomposition of powder diffraction patterns and profile analysis of pair correlation functions

FIT is an interactive computer program for fitting analytical models to powder diffraction patterns and to pair correlation functions. FIT has been written in Turbo C and runs on IBM XT/AT or compatible personal computers.

[Detection of HIV infection using the immunofluorescence test]

The author examined, using the immunofluorescence test, 107 ant HIV positive sera and 114 sera with false reactions in the ELISA test. He proved a high sensitivity and specificity of the immunofluorescence test in the detection of anti-HIV antibodies, comparable with Western-blot's technique and he established the value of the immunofluorescence test for the identification of the virus antigen on isolation of the virus from HIV infected patients.

[Dynamics of the antibody response and p24 antigenemia in HIV-1 infected individuals in Czechoslovakia]

In a group of 83 anti HIV-1 positive subjects the antibody response against different structural viral proteins was investigated concurrently with assessment of p 24 antigenaemia. Disappearance of antibodies against the capsidal antigen p 24 was recorded in 12% of 42 patients with ARC and AIDS. On the other hand, these antibodies persisted in all 41 asymptomatic infections throughout the three-year investigation period. Disappearance of antibodies against p 17 antigen was proved in 41% of the patients and in 22 subjects without clinical symptoms. The authors found a rising trend of antigenaemia p 24 in the course of HIV infection. The free p 24 antigen was detected in 62% patients with AIDS and only in 10% asymptomatic infections. The investigation confirmed the importance of investigations of the antibody response and p 24 antigenaemia in the prognosis of development of HIV infection and in monitoring of the effect of therapy.

RAD, a program for analysis of X-ray diffraction data from amorphous materials for personal computers

RAD is an interactive computer program for radial distribution analysis of X-ray diffraction data from amorphous materials. RAD has been written in Fortran 77 and runs on IBM PC/XT/AT or compatible computers.