Reinforcement learning for patient-specific optimal stenting of intracranial aneurysms

Developing new capabilities to predict the risk of intracranial aneurysm rupture and to improve treatment outcomes in the follow-up of endovascular repair is of tremendous medical and societal interest, both to support decision-making and assessment of treatment options by medical doctors, and to improve the life quality and expectancy of patients. This study aims at identifying and characterizing novel flow-deviator stent devices through a high-fidelity computational framework that combines state-of-the-art numerical methods to accurately describe the mechanical exchanges between the blood flow, the aneurysm, and the flow-deviator and deep reinforcement learning algorithms to identify a new stent concepts enabling patient-specific treatment via accurate adjustment of the functional parameters in the implanted state.

CE: Diagnosing and Managing Migraine

ABSTRACT

Roughly 90% of the U.S. population will develop a headache within their lifetime, and headache disorders account for more disability-adjusted life-years than all other neurologic disorders combined. Among primary headache disorders, the two most common are tension-type headache and migraine, with migraine identified as the most disabling. Here, the authors describe the importance of differentiating primary and secondary headache disorders and discuss the pathophysiology; clinical assessment; and outpatient management of the debilitating migraine headache, summarizing both acute and prophylactic treatment strategies that can substantially reduce associated disability.

Importance of the biofilm matrix for the erosion stability of Bacillus subtilis NCIB 3610 biofilms

Erosion of bacterial biofilms is dependent on the composition of the biofilm matrix and the surrounding chemical environment.

Synchronous subcutaneous granular cell tumours, a rare presentation

We describe a unique presentation of a rare disease presentation of a granular cell tumour. A 36-year-old woman presents with a large symptomatic left flank mass that had been slowly increasing in size. Multiple synchronous subcutaneous masses were found at presentation on the left breast, right auricle and right cheek. After diagnosis of granular cell tumour by core needle biopsy, the masses were excised with histopathological and immunohistochemical analysis of both specimens confirming the presence of non-malignant granular cell tumours. Granular cell tumours are rare Schwann cell derived tumours that are typically asymptomatic and benign. These tumours are most often located in the head and neck, with multifocal disease present in approximately 5-16% of patients. Final pathology is necessary for diagnosis and frozen section is rarely helpful. Malignancy is present in approximately 2% of cases and can be diagnosed by the presence of a high mitotic rate, large nucleoli, necrosis, spindling and pleomorphism are other suspicious features. Granular cell tumours do not generally require adjuvant treatment. The mainstay of therapy is surgical resection with surveillance.

Oncological long-term outcome of 4772 patients with prostate cancer undergoing radical prostatectomy: does the anaesthetic technique matter?

INTRODUCTION

Recent data suggest that using additional neuroaxial anaesthesia during oncological surgery is associated with favourable recurrence-free survival, when compared with general anaesthesia alone. We assessed the impact of adjunctive perioperative spinal anaesthesia and dose of opioids on the oncological long-term outcome of patients following radical prostatectomy.

METHODS

We selected patients from our institutional review board-approved database who consecutively underwent radical prostatectomy between 2002 and 2007. Patients were stratified by type of anaesthesia, administered as general anaesthesia alone, or spinal anaesthesia in addition to general anaesthesia. Biochemical recurrence-free survival, metastasis-free survival and overall survival were analysed by a multivariate Cox regression model and by Kaplan-Meier analysis in propensity-score based matched cohorts, adjusted for standard clinico-pathological variables and year of surgery.

RESULTS

Overall, 4772 patients were analysed. Regarding the type of anaesthesia no significant difference for biochemical recurrence-free survival, metastasis-free survival and overall survival was analysed by a multivariate Cox regression model (p = 0.5, 0.8 and 0.7). The Kaplan-Meier analyses after propensity-score matched based comparisons revealed no significant difference depending on type of anaesthesia for biochemical recurrence-free survival, metastasis-free survival and overall survival (p = 0.6, 0.1 and 0.4). The same accounted for a propensity-score matched model adjusted for the year of surgery on biochemical recurrence-free survival (p = 0.7).

CONCLUSIONS

The oncological outcome after radical prostatectomy was not affected by the adjunctive use of spinal anaesthesia.

S3 guidelines for intensive care in cardiac surgery patients: hemodynamic monitoring and cardiocirculary system

Hemodynamic monitoring and adequate volume-therapy, as well as the treatment with positive inotropic drugs and vasopressors are the basic principles of the postoperative intensive care treatment of patient after cardiothoracic surgery. The goal of these S3 guidelines is to evaluate the recommendations in regard to evidence based medicine and to define therapy goals for monitoring and therapy. In context with the clinical situation the evaluation of the different hemodynamic parameters allows the development of a therapeutic concept and the definition of goal criteria to evaluate the effect of treatment. Up to now there are only guidelines for subareas of postoperative treatment of cardiothoracic surgical patients, like the use of a pulmonary artery catheter or the transesophageal echocardiography. The German Society for Thoracic and Cardiovascular Surgery (Deutsche Gesellschaft für Thorax-, Herz- und Gefässchirurgie, DGTHG) and the German Society for Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und lntensivmedizin, DGAI) made an approach to ensure and improve the quality of the postoperative intensive care medicine after cardiothoracic surgery by the development of S3 consensus-based treatment guidelines. Goal of this guideline is to assess the available monitoring methods with regard to indication, procedures, predication, limits, contraindications and risks for use. The differentiated therapy of volume-replacement, positive inotropic support and vasoactive drugs, the therapy with vasodilatators, inodilatators and calcium sensitizers and the use of intra-aortic balloon pumps will also be addressed. The guideline has been developed following the recommendations for the development of guidelines by the Association of the Scientific Medical Societies in Germany (AWMF). The presented key messages of the guidelines were approved after two consensus meetings under the moderation of the Association of the Scientific Medical Societies in Germany (AWMF).

[Guidelines for intensive care in cardiac surgery patients: haemodynamic monitoring and cardio-circulatory treatment guidelines of the German Society for Thoracic and Cardiovascular Surgery and the German Society of Anaesthesiology and Intensive Care Medicine]

Hemodynamic monitoring and adequate volume-therapy, as well as the treatment with positive inotropic drugs and vasopressors, are the basic principles of the postoperative intensive care treatment of patient after cardiothoracic surgery. The goal of these S3 guidelines is to evaluate the recommendations in regard to evidence based medicine and to define therapy goals for monitoring and therapy. In context with the clinical situation the evaluation of the different hemodynamic parameters allows the development of a therapeutic concept and the definition of goal criteria to evaluate the effect of treatment. Up to now there are only guidelines for subareas of postoperative treatment of cardiothoracic surgical patients, like the use of a pulmonary artery catheter or the transesophageal echocardiography. The German Society for Thoracic and Cardiovascular Surgery and the German Society for Anaesthesiology and Intensive Care Medicine made an approach to ensure and improve the quality of the postoperative intensive care medicine after cardiothoracic surgery by the development of S3 consensus-based treatment guidelines. Goal of this guideline is to assess available monitoring methods and their risks as well as the differentiated therapy of volume-replacement, positive inotropic support and vasoactive drugs, the therapy with vasodilators, inodilators and calcium-sensitizers and the use of intra-aortic balloon pumps. The guideline has been developed according to the recommendations for the development of guidelines by the Association of the Scientific Medical Societies in Germany (AWMF). The presented key messages of the guidelines were approved after two consensus meetings under the moderation of the Association of the Scientific Medical Societies in Germany (AWMF).

Association between vasopressor dependence and early outcome in patients after cardiac surgery

Arterial hypotension with vasopressor dependence is a major problem after cardiac surgery. We evaluated the early postoperative course of 1558 consecutive patients scheduled for cardiac surgery, and compared the outcome of patients with and without vasopressor dependence (defined as the need for > 0.1 microg x kg(-1) x h(-1) noradrenaline for > 3 h in the face of normovolaemia). Vasopressor dependence was diagnosed in 424 patients (27%) and was associated with a higher incidence of postoperative renal failure (67 (15.7%) vs 7 (0.6%), respectively; p < 0.0001), a longer duration of ventilation (median IQR [range]) 14 (8-26 [6-39]) h vs 8 (5-11 [4-32]) h; p < 0.0001), a greater need for red cell transfusion (3 (1-5 [0-10]) units vs 1 (0-2 [0-4]) units; p < 0.001) and a longer length of stay in the ICU (4 (2-6 [2-9] days) vs 2 (1-3 [1-6] days; p < 0.001). Vasopressor dependence could be predicted from a combination of factors, including pre-operative ejection fraction < 37%, cardiopulmonary bypass lasting > 94 min, and postoperative interleukin-6 > 837 pg x ml(-1).

A phase I and pharmacokinetic study of 1843U89, a noncompetitive inhibitor of thymidylate synthase, in patients with advanced solid malignancies

This study was performed to assess the feasibility of administering 1843U89, a potent, noncompetitive inhibitor of thymidylate synthase that does not require polyglutamation for activity, as a 2-min i.v. infusion daily for 5 days every 3 weeks, to determine whether folic acid supplementation ameliorates the toxic effects of 1843U89 and permits further dose escalation, and to recommend doses of 1843U89 administered without and with folic acid for further clinical evaluations. The study also sought to characterize the pharmacokinetic behavior of 1843U89 and to seek preliminary evidence of anticancer activity. Patients with advanced solid malignancies were treated with escalating doses of 1843U89 as a 2-min i.v. infusion daily for 5 days every 3 weeks. Initially, patients were treated in the absence of high-dose folic acid until dose-limiting toxicity was consistently noted. Next, patients were treated with escalating doses of 1843U89 preceded by 1000 mg of folic acid administered p.o. 30 min before each of the 5 daily doses of 1843U89. Patients (32) received 101 total courses of 1843U89 at doses ranging from 1 to 6 mg/m(2)/day with and without folic acid. At the 2 mg/m(2)/day dose level without folic acid, 2 of 7 new patients experienced dose-limiting toxicity, principally neutropenia, mucositis, and malaise in 3 of 11 courses. 1843U89 doses were further increased with folic acid to 6 mg/m(2)/day, but repetitive treatment was not feasible at this dose level because of an unacceptable high incidence of severe neutropenia and mucositis. Other toxicities included thrombocytopenia, rash, and fever. In contrast, repetitive treatment at the 5 mg/m(2)/day dose level was feasible. The pharmacokinetics of 1843U89 were neither dose dependent nor affected by folic acid. On day 1, clearance, terminal half-life, and steady-state volume of distribution values averaged 47.1 +/- 21.7 ml/min/m(2), 7.72 +/- 4.09 h, and 16.7 +/- 8.8 liter/m(2)/h, respectively. The results of the study indicate that the administration of 1843U89 as a 2-min infusion daily for 5 days every 3 weeks without and with folic acid is feasible at 1843U89 doses as high as 2 and 5 mg/m(2)/day, respectively. Because folic acid pretreatment results in no diminution of the antitumor activity of 1843U89 in preclinical studies and ameliorates the toxic effects of 1843U89 in both preclinical models and cancer patients, the therapeutic index of 1843U89 may be enhanced by folic acid pretreatment and, therefore, the development of 1843U89 with folic acid is warranted. However, the question of whether to administer 1843U89 at a dose of 2 mg/m(2)/day with folic acid, which is associated with negligible toxicity, or at its highest feasible dose with folic acid, 5 mg/m(2)/day, should be addressed in appropriately designed trials.

Markers of myocardial ischemia after minimally invasive and conventional coronary operation

BACKGROUND

The purpose of this study was to evaluate the course of serum markers of myocardial tissue damage after two different types of minimally invasive coronary surgical procedures (MICS) as compared with conventional coronary artery bypass grafting (CABG).

METHODS

We enrolled 87 patients with one- or two-vessel disease scheduled for one of the three procedures: minimally invasive direct coronary artery bypass grafting (MIDCABG) by lateral thoracotomy (n = 29), the OCTOPUS method by median sternotomy (n = 27), and CABG (n = 31). Creatine kinase activity (CK), creatine kinase MB activity (CK-MB act), creatine kinase MB mass concentration (CK-MB mass), myoglobin concentration (MG), and cardiac troponin I concentration (cTnI) were measured perioperatively until the second postoperative day.

RESULTS

Creatine kinase-MB, CK-MB mass, and cTnI were significantly higher after CABG and were nearly maintained within the normal range in MICS. Creatine kinase and MG were significantly lower in the OCTOPUS group than in the MIDCABG or CABG groups.

CONCLUSIONS

Minimally invasive coronary surgical procedures cause less myocardial injury than CABG as indicated by specific serum markers. However, higher CK and MG reflect more substantial skeletal muscle trauma during MIDCABG operation compared with OCTOPUS procedures.

Methicillin-resistant Staphylococcus aureus in the community: a hospital-based study

To determine the proportion of methicillin-resistant Staphylococcus aureus (MRSA) among patients presenting for hospitalization and to assess risk factors for MRSA carriage, we conducted a study for 13 months at five Pittsburgh-area hospitals. Of 504 S aureus identified, 125 (25%) were MRSA. Independent risk factors for MRSA included organ transplantation, employment in a healthcare facility, pressure sores, tube feeding, and hospitalization within the preceding year.

[Surgical treatment of chronic pancreatitis in children]

Chronic relapsing pancreatitis and its hereditary form are very rare in children. Our experience with early operative treatment in nine children is presented. The good exocrine and endocrine function of the pancreas in these patients justifies early operation when typical changes of the pancreatic duct are present since it shortens the relapsing clinical course and maintains good function of the pancreas.

Surgical therapy and follow-up of pancreatitis in children

BACKGROUND

Acute and chronic pancreatitis in children differ from that in adults both from the etiology and the therapeutic approach. Within the frame of a blunt abdominal trauma-the most frequent cause in children-acute pancreatitis is often detected by emergency laparotomy and external drainage is recommended. Chronic relapsing pancreatitis, and particularly its hereditary form, is very rare in children and requires a different therapeutic concept. The results of surgical therapy for both forms of pancreatitis in childhood were evaluated in the present study.

METHODS

Sixteen patients with acute and chronic relapsing pancreatitis were operated on in our facility between 1976 and 1988. Their history and postoperative course were analyzed in a retrospective study, including a final examination at the end of the follow-up period.

RESULTS

Eight children with acute pancreatitis were operated on at an average age of 6 years and were followed up for an average of 7.5 years, with good results. The remaining children, aged between 3 and 14 years (average age of 9 years), were operated on for chronic relapsing pancreatitis. Our experience with early operative treatment, on average 2.7 years after onset of symptoms, is presented. Only three patients experienced a mild relapse during the follow-up period of 2-13 years (average of 5.4 years).

CONCLUSIONS

For acute pancreatitis in childhood, operative treatment by inner drainage is necessary and effective only in case of complications, should conservative treatment fail. In children with chronic relapsing pancreatitis, the good exocrine and the normal endocrine function of the pancreas in these patients justified the early operation. Timely treatment is recommended in cases with typical changes of the pancreatic duct so as to shorten the relapsing clinical problems of the children and to maintain the function of the pancreas.

A mathematical model for analysis of pharmacologically induced changes in the kinetics of cardiac muscle

A mathematical model of the isometric contraction of cardiac muscle is developed and utilized to characterize the inotropic and lusitropic effects of cardioactive compounds in isolated guinea pig left atria. In contrast to metrics that are based on minima and maxima of an isometric twitch and its derivative function, the entire time course of the twitch is used to quantify the kinetics of the contraction-relaxation cycle. The model relates observed tension to a time-dependent activation function that describes generation of internal force and a coupling function that determines mechanical response to the activation function. The model is structured so that it is suitable for nonlinear curve fitting to observed data. Results obtained using the model for fitting experimental data from tissues treated with different classes of cardioactive compounds agree with more qualitative results presented by other authors. Experiments using the model to fit data over an extended (90 min) time course revealed differences in the kinetic profiles of milrinone and forskolin. Computer simulations that demonstrate the effect of each model parameter on twitch kinetics are presented, and the relationships between the model and other theoretical and empirical models of cardiac muscle are discussed. The mathematical model is useful to enable a more quantitative understanding of the kinetics of cardiac muscle contraction and relaxation and identify compounds that may be selective for inotropic or lusitropic effects.

[Photodynamic diagnosis of neoplasms of the mouth cavity after local administration of 5-aminolevulinic acid]

BACKGROUND

The aim of photodynamic diagnosis (PDD) is the complete visualization of all neoplastic lesions in a tumorous organ after topical or systemic application of a tumor selective photosensitizer. In this investigation we performed semiquantitative fluorescence measurements following topical application of 5-aminolevulinic acid (5-ALA) in 11 patients with neoplastic lesions of the oral cavity.

METHODS

Time course and type of porphyrin accumulation were analyzed in neoplastic and surrounding normal tissue by measuring emission spectra of 5-ALA-induced protoporphyrin IX (PpIX) fluorescence at regular intervals for up to three hours following 15 min continuous rinsing of a 0.4% 5-ALA solution. After excitation with violet light of a high pressure xenon arc lamp (375-440 nm), fluorescence images in the red spectral range from the tumor tissue and the corresponding macroscopic visible tumor were recorded with a CCD camera. A quantitative analysis of the fluorescence contrast in neoplastic and surrounding tissue was performed using an optical multichannel analyzer.

RESULTS

PpIX fluorescence was detected in the oral mucosa of all patients after local application of 5-ALA. PpIX in neoplastic tissue accumulated earlier in comparison to the surrounding normal tissue. The fluorescence contrast between tumor and host tissue was 10:1 and the maximum fluorescence was measured 1-2 hours following 5-ALA application.

CONCLUSION

Labeling of mucosal lesions of the oral cavity with PpIX fluorescence induced by the local application of 5-ALA seems to be a promising diagnostic procedure for neoplastic lesions. Further investigations are required to assess the value of this new diagnostic procedure as a non-invasive and sensitive method for patients with head and neck cancer not only in pre- and postoperative diagnostic studies but also for a fluorescence-guided resection of tumors.

Effect of photodynamic treatment of human endothelial cells on cell volume and cell viability

Photodynamic therapy (PDT) has yielded promising results in the treatment of malignant tumors. However, the mechanisms leading to tumor destruction during PDT are still not completely understood. In addition to effects on the microcirculation, damage to cellular structures has been observed following exposure of cells to PDT. A phenomenon preceding these events might possibly be cell swelling. We therefore studied the influence of treatment with Photofrin(R) (PF) and laser light on volume changes and cell viability of endothelial cells. Endothelial cells were obtained from human umbilical cord veins (HUVEC) by an adaption of the method of Maruyama. After subcultivation the cells were harvested and transferred as a cell suspension into a specially designed incubation chamber. Cells received either PF in concentrations of 1.5 or 3.0 mu g/ml and laser illumination 60 min post incubation (630 nm; 40 mW/cm(2), 4 Joule), PF alone, or laser treatment only. Following start of PF incubation and after phototreatment cell samples were taken for volume measurements using flow cytometry, and for studies of cellular morphology using scanning electron microscopy. Simultaneously, cell viability was monitored by the trypan blue exclusion test and the colorimetric MTT assay. Both control groups, HUVEC receiving PF or laser treatment alone, revealed constant cell volumes and cell viability during the entire course of the experiment. After PDT (60 min post-incubation) with 1.5 and 3.0 mu g PF/ml cell volume of HUVEC was increased at 15 min to 122%+/-6% and 140%+/-10% of baseline (100%), at 60 min to 152%+/-9% and 134%+/-18%, respectively (p<0.01). The number of viable cells was significantly reduced of samples treated with 1.5 and 3.0 mu g PF/ml at 15 min after PDT to 81%+/-3% and 76%+/-10% of baseline (100%), at 60 min after PDT to 32%+/-14% and 20%+/-15%, respectively (p<0.01). Scanning electron microscopy of cells exposed to PDT following 60 min incubation with Photofrin (3.0 mu g/ml) revealed significant cell damage. At the highest PF concentration HUVEC showed loss of microvilli and formation of blebs on the cellular surface. Our study demonstrates that PDT induces a significant increase in endothelial cell volume and a loss of cell viability. We suggest that swelling and damage of endothelial cells following PDT is a primary event finally contributing to cessation of blood flow and subsequent necrosis of tumors.

The alpha 1C-adrenoceptor in human prostate: cloning, functional expression, and localization to specific prostatic cell types

1. Benign prostatic hyperplasia (BPH) causes urinary obstruction in aging men that frequently requires surgery to relieve the symptoms of urinary retention, nocturia, and micturition. Smooth muscle tone which contributes to the urethral constriction in the enlarged gland appears to be mediated by the alpha 1-adrenoceptors. In this paper, molecular and pharmacological approaches are used to establish the role played by the alpha 1C-adrenoceptor subtype in the prostate. 2. The alpha 1-adrenoceptor subtype(s) expressed in human prostate were investigated by use of polymerase chain reaction (PCR), Northern blot, and in situ hybridization. The alpha 1C subtype was found in both prostate stromal and glandular cells while alpha 1B and alpha 1D subtypes were expressed in glandular cells. High expression levels for alpha 1C were observed in prostate cancer tissues in both stroma and glandular cells. 3. Full length alpha 1C-adrenoceptor cDNA was cloned from human prostate. Stable mammalian cell lines expressing human alpha 1B-, alpha 1C-, and alpha 1D-adrenoceptors were made. Membranes prepared from these cell lines and human prostate were used to evaluate the pharmacological profiles of human alpha 1B-, alpha 1C- and alpha 1D-adrenoceptors in comparison to human prostate. Leverage plot analysis of compound affinities determined by competition for [125I]-I-HEAT binding demonstrated that the alpha 1C subtype is the predominant alpha 1-adrenoceptor in human prostate. 4. The alpha 1-adrenoceptors cause smooth muscle constriction by coupling to IP3 turnover and intracellular Ca2+ release. Using stable cell lines to measure IP3 production in response to noradrenaline, alpha 1C stimulated IP3 production most efficiently, with alpha 1B at an intermediate level, while little IP3 above background could be detected with alpha 1D. These results supported a functional role of the alpha 1C-adrenoceptor on prostate smooth muscle constriction by noradrenaline stimulation.

Photodynamic therapy induces expression of interleukin 6 by activation of AP-1 but not NF-kappa B DNA binding

Inducibility and regulation of the pleiotropic cytokine interleukin 6 (IL-6) upon photodynamic therapy (PDT) was studied in the epithelial cell line HeLa. Photofrin-mediated photosensitization resulted in a rapid and dose-dependent induction of IL-6 mRNA production. Maximal levels were reached after 4 h and had decreased to baseline levels after 24 h. This photochemical induction of IL-6 transcription was followed by a strong secretion of IL-6 protein. In comparison to stimulation by 12-O-tetradecanoylphorbol-13-acetate, the kinetics of IL-6 mRNA and protein synthesis after PDT were delayed, although the maximal amounts of secreted IL-6 protein were comparable. As compared to UV irradiation, on the other hand, PDT-induced IL-6 protein levels were 2- to 10-fold higher and were detectable 4 h earlier. Several potentially relevant regulatory DNA elements of the IL-6 promoter were analyzed by gel retardation assays for PDT-induced protein binding. Interestingly, increased AP-1 DNA binding was detected only at the distal AP-1-specific motif and not at the proximal site, differing in 1 bp. Binding of c-Fos-containing AP-1 heterodimers to the specific motif was up-regulated 30 min after PDT, reaching maximal activity at 4 h. This PDT-induced AP-1 activation was independent from protein kinase C activity. Photosensitization did not induce increased binding at the well-characterized NF-kappa B element, nor at the multiple cytokine- and second messenger-responsive element of the IL-6 promoter. By analyzing the molecular mechanisms of IL-6 up-regulation upon PDT, we provide evidence for regulatory differences compared to UV light, ionizing irradiation, or stimulation by phorbol ester. Furthermore, this study suggests that the "proinflammatory" cytokine IL-6 might be involved in the inflammatory reaction and subsequent immunological antitumor responses.

Measuring second-order selection bias in a work site health program

Magnitude and direction of second-order self-selection bias were assessed in a sample of 93,807 IBM employees who participated in the company's Voluntary Health Assessment (VHA) Program, by comparing repeat participants with one-time participants and by simulating selection into the repeat sample. One-time and repeat VHA participants differed systematically but not uniformly in several health characteristics. Repeat participants improved significantly in risk-relevant behaviors and health risk measures. Simulation of selection bias by excluding healthier or less healthy participants from the repeat VHA sample showed findings of gain to be robust. In studies of gain, second-order selection bias cannot automatically be assumed to inflate gain nor to be of sufficient magnitude to affect conclusions about program effects. Simulation is a useful tool for gauging direction and magnitude of selection bias.

[Damage to tumor cells by photodynamic therapy]

Photodynamic therapy (PDT) is a new, promising method in the treatment of cancer. To gain insights into PDT-mediated tumour destruction we studied the influence of treatment with Photofrin and laser light on changes in cell volume and cell viability. A-Mel-3 tumour cells were subjected to Photofrin or illumination with laser light, or a combination of both (PDT). Cell volume was measured by flow cytometry and cell viability by the trypan blue exclusion test for up to 60 min after PDT and the respective controls. In addition, scanning and transmission electron microscopy were performed. Tumour cells incubated in concentrations of 0.75, 1.5 and 3.0 micrograms Photofrin/ml revealed a rapid increase in cell volume to 117%, 207% and 235% 30 min after PDT and to 147%, 210% and 199% 60 min after PDT. Cell viability with 1.5 and 3.0 micrograms Photofrin/ml and laser light was reduced to 83% and 44% at 30 min after PDT and to 38% and 17% 60 min after PDT. At Photofrin concentrations of 1.5 micrograms/ml and exposure to laser light scanning electron microscopy revealed extreme loss of microvilli and formation of blebs on the cellular surface. Transmission electron microscopy showed swollen mitochondria and ruptures of the cell membrane. This study demonstrates that PDT induces a significant time-dependent and dose-related increase in tumour cell volume. We suggest that the PDT-induced swelling of tumour cells contributes to the increase of interstitial fluid pressure and to impairment of microvascular perfusion of tumours.

Prosthetic valve endocarditis resulting from nosocomial bacteremia. A prospective, multicenter study

OBJECTIVE

To determine the incidence of endocarditis in bacteremic patients with prosthetic heart valves and the risk factors for and the effect of duration of antibiotic therapy on development of endocarditis in such patients.

DESIGN

Multicenter, prospective observational study.

SETTING

Six university teaching hospitals with high-volume cardiothoracic surgery.

PARTICIPANTS

One hundred seventy-one consecutive patients with prosthetic heart valves who developed bacteremia during hospitalization.

MEASUREMENTS AND MAIN RESULTS

Patients were evaluated when they were identified as having bacteremia and 1, 2, 6, and 12 months after its occurrence. Of 171 patients, 74 (43%) developed endocarditis: Fifty-six (33%) had prosthetic valve endocarditis at the time bacteremia was discovered ("endocarditis at outset"), whereas 18 (11%) developed endocarditis a mean of 45 days after bacteremia was discovered ("new endocarditis"). Mitral valve location and staphylococcal bacteremia (Staphylococcus aureus or S. epidermidis) were significantly associated with the development of "new" endocarditis. All 18 cases of new endocarditis were nosocomial, and in 6 of these cases (33%) bacteremia was acquired via intravascular devices. Twenty-one patients without evidence of endocarditis at the time of bacteremia received short-term antibiotic therapy (< 14 days); 1 patient (5%) developed endocarditis. Eleven of 70 patients (16%) who received long-term antibiotic therapy (> 14 days) developed endocarditis (P > 0.2).

CONCLUSIONS

Bacteremic patients with prosthetic heart valves were at notable risk for developing endocarditis, even when they received antibiotic therapy before endocarditis developed and regardless of the duration of such therapy. Intravascular devices were a common portal of entry.

Effect of dietary n-3 versus n-6 polyunsaturated fatty acids on hepatic excretion of cholesterol in the hamster

Dietary polyunsaturated fatty acids of the n-6 and the n-3 class show differing effects on serum lipids and hepatic lipoprotein metabolism, which could be induced by alterations in hepatocellular cholesterol balance. As both fatty acid classes exert parallel effects on lipoprotein uptake and synthesis of cholesterol in the liver, we studied whether they have differing effects on the excretory pathways for cholesterol. Male Syrian hamsters were fed for 3 weeks low-cholesterol diets supplemented (9% w/w) with either saturated (coconut fat), n-6 unsaturated (safflower oil) or n-3 unsaturated fatty acids (fish oil), which shifted the serum lipid levels. N-6 unsaturated fatty acids increased both the synthesis of cholic acid (+57%; P = 0.05) and, in fistula bile, the secretion of cholesterol (+37%; P < 0.05 vs. saturated fatty acids). By contrast, n-3 unsaturated fatty acids did not enhance synthesis of cholic acid or biliary secretion of cholesterol (-30%, NS). The fatty acid pattern of biliary phospholipids was modified according to the major unsaturated fatty acids in the diet. The alterations both in phospholipid fatty acid composition and in secretory ratio of cholesterol to phospholipids and bile acids persisted during controlled secretion of taurocholic acid at increasing rates. In conclusion, hepatic excretion of cholesterol is increased on dietary n-6 unsaturated fatty acids, and low on n-3 unsaturated fatty acids. These two dietary fatty acid classes change differently the fatty acid composition of biliary phospholipids and the secretory ratio of cholesterol to phospholipids and bile acids in bile.

Endoscopically-controlled electrohydraulic intracorporeal shock wave lithotripsy (EISL) of salivary stones

Twenty-nine patients with salivary stones were treated with the endoscopically-controlled electrohydraulic shock wave lithotripsy (EISL). This new minimally invasive treatment of sialolithiasis is performed under local anesthesia on an outpatient basis with little inconvenience to the patient. For endoscopy, a flexible fibroscope with an additional probe to generate shock waves is placed into the submandibular duct and advanced until the stone is identified. For shock wave-induced stone disintegration, the probe electrode must be placed 1 mm in front of the concrement. The shock waves are generated by a sparkover at the tip of the probe. By means of the endoscopically-controlled shock wave lithotripsy it was possible to achieve complete stone fragmentation in 20 out of 29 patients without serious side effects. In three patients, only partial stone fragmentation could be achieved due to the stone quality. Endoscopically-controlled electrohydraulic intracorporeal shock wave lithotripsy represents a novel minimally invasive therapy for endoscopically accessible salivary gland stones. The advantage in comparison to the endoscopically-controlled laser lithotripsy will be discussed.

Microbiology, infection control, immunizations, and infectious disease exposure: education and practices in United States nursing schools

BACKGROUND

Previous data suggest that nursing students in the United States are inadequately protected against hepatitis B. This survey focused on the immunization and education practices, infection control knowledge, and follow-up to infectious disease exposure by U.S. nursing schools.

METHODS

To ascertain education requirements, immunization practices, and infectious disease postexposure follow up, a survey was sent to the director or dean of 1164 U.S. nursing schools.

RESULTS

Seven hundred sixty-five schools (65.7%) responded to the survey. A microbiology course was required before clinical experience by 49% of schools. Clinical experience in the operating room was given by 16%, 65% of schools offered infectious and communicable disease courses, and 98% offered universal precaution instructions. The hepatitis B vaccine was required by 11%; 2% required yearly influenza vaccination. In a comparison of programs, the diploma schools were more likely to have written policies for infectious disease exposure follow-up and to use appropriate agencies for exposure follow-up (p = 0.0001).

CONCLUSIONS

A microbiology course before clinical experience should be encouraged. Immunization policies and infectious disease exposure follow-up are currently inadequate in U.S. associate degree and baccalaureate nursing programs.

[Microcirculatory effects of photodynamic therapy with hematoporphyrin derivative]

Hematoporphyrin derivative photosensitizes selectively malignant tumors following intravenous administration and shows typical fluorescence patterns in the range between 630 nm and 690 nm. Irradiation with laser light (630 nm) causes selective tumor necrosis due to a phototoxic effect. The site of action of this "photodynamic treatment (PDT)" remains obscure. In this study it could be demonstrated that directly after PDT a selective haemorrhage and thrombosis of blood vessels occurs in the tumor tissue. Furthermore, the arterioles of the surrounding normal tissue constrict completely. Venules of normal tissue showed slow thrombosis. Basically, the result of photodynamic treatment was a complete breakdown of tumor tissue microcirculation accompanied by partial damage to the surrounding normal tissue perfusion. This evaluation of the impact of PDT on tumor microcirculation led to the conclusion that a primary site of action of photodynamic therapy may contribute to the selective destruction of tumor microcirculation.

[Time resolved laser fluorescence microscopy of hematoporphyrin derivative in vivo]

Laser-assisted fluorescence microscopy proved a powerful method for quantitative in vivo measurement of HpD fluorescence. Therefore the aim of the present work was to study the distribution of HpD in tumor vs. adjacent tumor-free tissue of 10 animals over a period of 8 days. We measured additionally the differences in HpD uptake in different tumor subcompartments. In tumor tissue HpD fluorescence showed maximum values 5-9 hours after i.v. application of the drug. The relation tumor-free tissue at that time was about 3-8. The third day of examination showed nearly identical values for both tissues. Between day 5 and day 8 we found an increase of HpD contents in tumor vs. normal tissue in 50% of the examined animals. Comparative measurements in the tumor centre and the tumor edge showed a preferential uptake of HpD in the tumor edge area. Probably the higher retention of HpD in this area is due to the oedema zone surrounding the tumor and to extravasation of HpD.