X-ray generation by fs-laser processing of biological material.

The use of ultrashort pulse lasers in medical treatments is increasing and is already an essential tool, particularly in the treatment of eyes, bones and skin. One of the main advantages of laser treatment is that it is fast and minimally invasive. Due to the interaction of ultrashort laser pulses with matter, X-rays can be generated during the laser ablation process. This is important not only for the safety of the patient, but also for the practitioner to ensure that the legally permissible dose is not exceeded. Although our results do not raise safety concerns for existing clinical applications, they might impact future developments at higher peak powers. In order to provide guidance to laser users in the medical field, this paper examines the X-ray emission spectra and dose of several biological materials and describes their dependence on the laser pulse energy.

On the diffraction pattern of bundled rare-earth silicide nanowires on Si(0 0 1).

Motivated by the complex diffraction pattern observed for bundled rare-earth silicide nanowires on the Si(0 0 1) surface, we investigate the influence of the width and the spacing distribution of the nanowires on the diffraction pattern. The diffraction pattern of the bundled rare-earth silicide nanowires is analyzed by the binary surface technique applying a kinematic approach to diffraction. Assuming a categorical distribution for the (individual) nanowire size and a Poisson distribution for the size of the spacing between adjacent nanowire-bundles, we are able to determine the parameters of these distributions and derive an expression for the distribution of the nanowire-bundle size. Additionally, the comparison of our simulations to the experimental diffraction pattern reveal that a (1 × 1)-periodicity on top of the nanowires has to be assumed for a good match.

Transcranial magnetic stimulation reveals complex cognitive control representations in the rostral frontal cortex.

Convergent evidence suggests that the lateral frontal cortex is at the heart of a brain network subserving cognitive control. Recent theories assume a functional segregation along the rostro-caudal axis of the lateral frontal cortex based on differences in the degree of complexity of cognitive control. However, the functional contribution of specific rostral and caudal sub-regions remains elusive. Here we investigate the impact of disrupting rostral and caudal target regions on cognitive control processes, using Transcranial Magnetic Stimulation (TMS). Participants performed three different task-switching conditions that assessed differences in the degree of complexity of cognitive control processes, after temporally disrupting rostral, or caudal target regions, or a control region. Disrupting the rostral lateral frontal region specifically impaired behavioral performance of the most complex task-switching condition, in comparison to the caudal target region and the control region. These novel findings shed light on the neuroanatomical architecture supporting control over goal-directed behavior.

Arterial hypertension in adults after surgical treatment of aortic coarctation.

Despite primarily successful surgical repair of aortic coarctation (CoA), postoperative persistent, recurring, or newly developing hypertension is regarded as a risk factor of earlier mortality compared with a normal population. The present study shows that even after surgical correction of CoA many patients have hypertension at rest or during exercise. Out of 44 patients, 72% had a pathological profile at rest, 20% during exercise, and 53% during ambulatory blood pressure measurement. Regular checks on blood pressure are therefore necessary, including measurements at rest, during exercise, and under ambulatory conditions. Since these processes yield very different answers they should be combined and evaluated critically for a proper assessment of the blood pressure situation and effective treatment. Ambulatory blood pressure measurement allows the recognition of round-the-clock behavior of blood pressure and of patients with 'occult' or 'white-coat' hypertension, and furthermore it helps to control the effectiveness of the treatment. It thus makes an essential contribution to the postoperative care of patients after surgical treatment of CoA.

Pharmacokinetics of pantoprazole in patients with end-stage renal failure.

BACKGROUND: Pantoprazole is a selective inhibitor of the gastric H+/K+-ATPase with a low potential to interact with the cytochrome P450 enzyme system. Since pantoprazole is metabolized in the liver to metabolites which are mainly cleared by the renal route, it was the aim of this study to investigate its pharmacokinetics in patients with end-stage renal failure undergoing regular haemodialysis. METHODS: Eight patients with end-stage renal failure (creatinine clearance < 5 ml/min, age 45-65 years) on regular haemodialysis (duration of haemodialysis 4-5 h, cuprophan-dialyser Hemoflow E3, surface 1.3 m2) were given single i.v. doses of 40 mg pantoprazole one day before haemodialysis (A) and on a haemodialysis day immediately before the start of the haemodialysis (B). Concentrations of pantoprazole and metabolite M2 were determined in plasma and urine over 24 h and in timed samples of the dialysis fluid by HPLC. The protein binding was determined using equilibrium dialysis. RESULTS: The pharmacokinetic characteristics of pantoprazole AUC, t(1/2), CL and V(d area) (geometric means) were 2.4 mgxh/l, 0.63 h, 0.227 l/h/kg and 0.206 l/kg on day A (without dialysis) and 2.3 mgxh/l, 0.8 h, 0.237 l/h/kg and 0.273 l/kg on day B (with dialysis), respectively. The protein binding was 96%. Pantoprazole was found in small amounts in the dialysis fluid (max. 2.1% of the dose) but not in the urine. Pantoprazole was well tolerated. In particular, there were no clinically relevant changes in blood count, electrolytes or liver enzymes. CONCLUSIONS: Haemodialysis has no influence on the pharmacokinetic characteristics of pantoprazole. Thus, pantoprazole is not dialysed to any relevant degree, and therefore no dose-adjustment is required for patients with end-stage renal failure undergoing regular haemodialysis treatment.

Migration of the uncemented Harris-Galante acetabular cup: results of the einbildroentgenanalyse (EBRA) method.

Seventy primary total hip arthroplasties using the Harris-Galante acetabular cup (Zimmer, Warsaw, IN) were prospectively examined. Over the entire period of 65.4+/-7.8 months, radiologic migration analysis was performed using the Einbildroentgenanalyse (EBRA) method at an accuracy of 1 mm. Although there was clinically no suspicion of prosthetic loosening in any case, in 8 implants (11.4%) migration of more than 1 mm was observed. Cranial migration occurred in 3 cases (1.1, 1.3 and 1.6 mm), medial migration in 3 cases (1.1, 1.1, and 2.9 mm), and lateral migration in 2 cases (1.1 and 1.1 mm). In the other 62 cases, however, no migration was traceable. Compared with measurements of other implant systems by means of the EBRA method published recently by other groups, the migration rate of the Harris-Galante cup was without exception lower and provided excellent midterm implant stability.

[Spiral CT and 3-dimensional reconstruction in evaluation of systemic venous obstruction after atrial switch operation for complete transposition of great vessels]. / Spiral-CT und dreidimensionale Rekonstruktion zur Beurteilung systemvenöser Obstruktionen nach Vorhofumkehroperation bei kompletter Transposition der grossen Gefässe.

We report findings in spiral-CT from 11 adolescent or adult patients after atrial switch operation. The results demonstrate that computed tomography, particularly with the use of three-dimensional surface reconstruction, is very useful as a highly sensitive procedure for the detailed depiction of residua and sequelae after inflow correction for complete transposition. Especially systemic venous obstruction (SVO) is a well know complication following Mustard procedure for transposition of the great arteries. Demonstration of such obstruction is important, since the recognition and quantification of caval obstruction by clinical techniques is unreliable and indeed often impossible. Imaging procedures such as spiral computed tomography are important for this purpose. Advantages of spiral computed tomography, particularly with three-dimensional reconstruction, are discussed. The images were compared with findings in echocardiography and/or angiography affecting the site of operation.

[Diagnostic imaging in follow-up of surgically treated stenosis of the aortic isthmus in adolescents and adults]. / Bildgebende Verfahren in der Verlaufskontrolle operierter Aortenisthmusstenosen bei Adoleszenten und Erwachsenen.

Local abnormalities of the ascending aorta, especially at the site of correction are well known complications after surgical correction of aortic coarctation. Regular follow-up is therefore necessary. Besides chest X-ray, transesophageal-echocardiography and substraction angiography, magnetic resonance imaging (MRI) and computertomography (CT) provide a complete and noninvasive examination of the great vessels. MRI and CT are ideally suited for this purpose.

Transesophageal echocardiographic assessment of superior vena cava thrombosis in patients with long-term central venous hemodialysis catheters.

In some patients with end-stage renal failure, arteriovenous fistulas cannot be created due to poor vessel conditions. Alternatively, hemodialysis (HD) can be performed using long-term central venous catheters. However, these dialysis catheters are associated with a presently unknown risk of superior vena cava (SVC) thrombosis. We examined 20 patients (11 female, 9 male, age 29-83 years) 1-48 (mean 15) months after transjugular insertion of a permanent single lumen silicone rubber HD catheter. All patients underwent both transthoracic (TTE) and biplane transesophageal (TEE) echocardiography. TTE visualized the catheter only when its tip was localized in the right atrium (2 patients), but did not succeed in adequate imaging of the SVC. In contrast, TEE allowed high quality imaging of the SVC in all patients and detected a SVC thrombosis in 6 patients; in 3 of them, caval thrombosis was subtotal. One additional patient showed a thrombus attached to the catheter tip alone. Dwelling time of catheters since insertion in the SVC was not significantly different in patients with and without thrombosis. Reduced blood flow during HD was observed in 5 of 7 patients with catheter-associated thrombi but also in 4 of 13 patients without evidence for caval thrombosis by TEE. It is concluded that thrombotic occlusion of the SVC is frequent in patients with long-term central venous access; it does not necessarily correlate with clinical signs but can easily be detected by TEE. Patients with long-term central venous hemodialysis catheters should undergo transesophageal echocardiography at regular intervals.

Skin microcirculation and regional peripheral resistance in patients with chronic renal anaemia treated with recombinant human erythropoietin.

Skin microcirculation and regional peripheral resistance were studied in 14 patients with renal anaemia during therapy with recombinant human erythropoietin. Haematocrit was raised from 20.0 to 31.3% after 10-12 weeks of treatment and remained stable over another period of 12 weeks. Antihypertensive treatment had to be intensified in five patients. Regional calf blood flow decreased significantly; accordingly, calculated peripheral vascular resistance was increased by more than 100%. However, transcutaneous oxygen pressure (37 degrees C and 44 degrees C) increased significantly. The pathological vasoconstrictor response of skin capillaries was not influenced. There were no significant differences of any parameter between the patients requiring reinforced antihypertensive therapy and those with stable blood pressure. In conclusion skin oxygenation may be improved by erythropoietin treatment to a large extent despite an increase in calculated total limb vascular resistance.

Long-term effects of treatment with recombinant human erythropoietin on haemodynamics and tissue oxygenation in patients with renal anaemia.

Regional peripheral vascular resistance, transcutaneous oxygen pressure and blood pressure were studied in seven normotensive, chronically haemodialysed patients with renal anaemia before and after 3 and 12 months of rHuEpo therapy. Haematocrit increased from 21% to 33% within 3 months of commencing therapy, and remained stable throughout the following observation time. Though regional blood flow of the calf was markedly reduced after 3 and 12 months of rHuEpo compared to pretreatment values, transcutaneous oxygen pressure was significantly increased after 3 months and remained constantly elevated after 12 months. Mean arterial blood pressure increased significantly by 7.3 mmHg after 3 months of rHuEpo treatment but did not reach hypertensive values and was no longer different from pretreatment values 12 months after the start of rHuEpo. Results of peripheral haemodynamic studies were compared to those obtained by measurement of central haemodynamics in four further normotensive anaemic patients. In these patients cardiac output decreased, total peripheral vascular resistance increased and blood pressure increased slightly (by 5.5 mmHg) when a haematocrit of 37% was reached after 8 weeks of rHuEpo therapy. These effects were partly reversed when the maintenance haematocrit decreased to 32% (after 16 weeks of rHuEpo). In summary rHuEpo treatment induced a long-term increase of the total and regional peripheral resistance, an increase of blood pressure within the normal range, and a decrease in cardiac output. Despite these changes tissue oxygenation improved.

Enhanced plasma and intracellular levels of main granulocyte components in diabetics on dialysis.

Intracellular and plasma levels of main granulocyte components (elastase, lactoferrin) were investigated in 25 diabetic and 27 nondiabetic patients undergoing regular hemodialysis treatment (RDT) as well as in 14 diabetic and 11 nondiabetic patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Diabetic patients on dialysis released more intragranular enzymes from neutrophils than their nondiabetic counterparts. Intracellular concentrations of granulocyte elastase and lactoferrin were only slightly higher in uremic diabetics than in uremic nondiabetics. However, both diabetic and nondiabetic hemodialysis patients displayed significantly lower cellular elastase and lactoferrin levels than healthy subjects. In addition, the diabetic dialysis patients had more protein catabolic fragments in the plasma as determined by trichloroacetic acid solubility. These observations were cited to support the hypothesis that not only is the hemodialysis procedure itself (with exposure to membranes) catabolic, but the diabetics are in double jeopardy. Thus, neutrophil abnormalities in diabetics on dialysis might affect the plasmatic proteinase inhibitor system and contribute to enhanced plasma protein degradation as well as to enhanced susceptibility to infections.

Effect of treatment with recombinant human erythropoietin on peripheral hemodynamics and oxygenation.

Slow progressive improvement of renal anemia from 21 up to 33% hematocrit by rhEPO treatment results in an increase of tissue oxygenation as indicated by a rise of the transcutaneous oxygen pressure. In normotensive patients this was accompanied by an increase in MAP (delta 6 mm Hg) within the normal range and a significant fall of the regional blood flow. These hemodynamic changes are caused by increases of the regional and presumably also of the total peripheral vascular resistance. Most likely the increase in total peripheral vascular resistance represents an autoregulatory event triggered by the rising tissue oxygenation. From the present data it is difficult to estimate to what extent the observed rise in hematocrit affects peripheral vascular resistance also via an increase of blood viscosity.

Echinococcal cyst causing bladder outlet obstruction. A case report.

The case of a 36-year-old black man with bladder outlet obstruction caused by a retrovesical echinococcal cyst is described. The diagnosis was made by conventional radiography, pelvic ultrasonography and computed tomography. The cyst was removed and the patient made an uneventful recovery.

Performance and biocompatibility of the FD 100 Gambrane hollow-fiber dialyzer.

In order to obtain performance data and biocompatibility characteristics of the two new Gambrane FD 100 polycarbonate hollow-fiber dialyzers (y-sterilized, dry or prefilled with isotonic saline) a paired in vivo evaluation was carried out. The measured data indicate that residual blood volume and small molecular weight clearances of Gambrane hollow-fiber dialyzers are not significantly different from comparable Cuprophan dialyzers. Small molecular clearance values are not affected by the significantly different ultrafiltration coefficients of the two tested FD 100 dialyzers. Biocompatibility of Gambrane as reflected by white blood cell count, platelet count and C3d is superior to Cuprophan.