Probing size variations of molecular aggregates inside chlorosomes using single-object spectroscopy.

We theoretically investigate the possibility to use single-object spectroscopy to probe size variations of the bacteriochlorophyll aggregates inside chlorosomes. Chlorosomes are the light-harvesting organelles of green sulfur and non-sulfur bacteria. They are known to be the most efficient light-harvesting systems in nature. Key to this efficiency is the organization of bacteriochlorophyll molecules in large self-assembled aggregates that define the secondary structure inside the chlorosomes. Many studies have been reported to elucidate the morphology of these aggregates and the molecular packing inside them. It is widely believed that tubular aggregates play an important role. Because the size (radius and length) of these aggregates affects the optical and excitation energy transport properties, it is of interest to be able to probe these quantities inside chlorosomes. We show that a combination of single-chlorosome linear polarization resolved spectroscopy and single-chlorosome circular dichroism spectroscopy may be used to access the typical size of the tubular aggregates within a chlorosome and, thus, probe possible variations between individual chlorosomes that may result, for instance, from different stages in growth or different growth conditions.

Microstructure formation in dip-coated particulate films.

The microstructure-dependence of dip-coated particulate thin films on the stability of an aqueous silica sol used as coating bath is studied. Different stability conditions are adjusted in the sol by changing electrolyte concentration and pH value. Care was taken to avoid pronounced aggregation of the particles before the coating process. The characterization of the stability behavior gives clear evidence of a non-DLVO contribution at low pH values that is attributed to hydration forces. Structural evolution of the particulate network during film formation is studied using a dialysis accumulation procedure. The viscosity of the accumulated sol is measured as a function of shear rate and related to the drying characteristic of the coating process. Atomic force microscopy (AFM), small-angle X-ray scattering (SAXS) and N2 sorption are used to obtain information on the surface and volume structure of the dip-coated films. The structure of coatings is found to distinctly vary with stability parameters. This is attributed to changing interactions during the first drying stage. Finally, the influence of coating structures on the light transmission properties is determined. A comparison between the extinction of the uncoated and the coated substrate revealed a difference of up to +/-50% in dependence on the microstructure.

[Palliative sedation at a university palliative care unit--a descriptive analysis]. / Palliative Sedierung auf einer universitären Palliativstation.

BACKGROUND: Palliative sedation (pS) is indicated in the presence of end-stage disease with treatment-refractory symptoms not tolerable for the patient. We investigated the practice of pS at a university palliative care unit. METHODS: Before starting pS the following data were documented: indication and decision making, type of sedation, life expectancy evaluated by the physician using the palliative prognostic index. Over the time of pS communication skills, depth of sedation, relief in symptoms, substitution of fluid and nutrition and used medications were collected. RESULTS: During evaluation time 99 patients died. 34 patients received pS (34 %). All patients suffered from cancer. Indications for palliative sedation were: terminal restlessness (56 %), dyspnea (39 %), pain (32 %), psychological distress (15 %), agitated delir (9 %), vomiting (3 %) and bleeding (3 %) (multiple nominations possible). In 31 cases (91 %) nurses were included for decision making. In 33 cases continuous sedation were initiated immediately (median duration 27.5 hours). The most applied medication was midazolam (94 %), sometimes combined with neuroleptics (44 %) and propofol (15 %). 91 % of the patients additionally received opioids. Artificial fluid was substituted in two cases. Palliative sedation started in the median 27.5 hours before death. The final physician assessment revealed complete symptom relief in 12 patients (35 %), very strong symptom relief in 20 patients (59 %) and moderate symptom relief in 2 patients (6 %). CONCLUSIONS: pS was successfully used as last resort for relief of treatment-refractory symptoms in one third of decedents at the investigated palliative care unit.

Glucagon expression shift in a syngeneic single-donor intrahepatic rat islet transplantation model.

In the native rat pancreas glucagon is expressed by alpha cells in the outer layer of the spheroid islet, producing a circular immunohistochemical staining pattern. We asked whether this pattern would remain unchanged after short-term and long-term intrahepatic islet transplantation. Islets of inbred Lewis rats were isolated with liberase, purified by discontinuous density gradients, handpicked, and cultured for 24 hours. After rats were rendered diabetic with streptozotocin, islets were implanted intraportally. Transplanted animals were sacrificed at 1 to 2 days (n = 5) or 100 days (n = 6). Islet clusters were detected by hematoxylen-and-eosin staining. Serial slides were stained for glucagon and insulin with the alkaline phosphatase and alkaline phosphate method at 1 to 2 days after transplantation islets with strong insulin expression were found within the portal vein branches. However, glucagon staining showed an incomplete circular staining pattern. After 100 days insulin expression remained strong, whereas only few glucagon-expressing cells were detected. Intrapancreatic islets showed inversion of the ratio of insulin- to glucagon-positive cells in favor of the glucagon-expressing cells that now composed the major part of the islet. Streptozotocin had selectively damaged beta cells in the recipient. In transplanted islets glucagon expression faded over time, possibly due to a functional involution process or to stress/inflammatory mechanisms during the isolation, transplantation, and the posttransplantation periods.

Pancreas oxygenation is limited during preservation with the two-layer method.

BACKGROUND: The two-layer method (TLM) for pancreas preservation reportedly improves islet yield and transplantation outcome relative to previous methods. Increased ATP concentrations support the hypothesis that these improvements are related to better oxygenation from the perfluorocarbon solution. However, there are limited direct measurements of oxygen partial pressure, (pO(2)) in pancreata preserved with the TLM. Theory predicts that only a small fraction of a human pancreas can be oxygenated externally. In this report we examine pancreas oxygenation with the TLM using theory and direct pO(2) measurements. METHODS: pO(2) profiles in cylindrical pancreata were calculated at various temperatures with a diffusion-reaction model. The pO(2) was measured using fiber optic sensors in the core of porcine pancreatic tissue preserved with the TLM in media saturated with 100% oxygen. RESULTS: The model predicts that at 8 degrees C, even in the absence of an external pO(2) gradient, oxygen penetration depth is about 1 mm and insensitive to pancreas diameter, while the oxygenated volume fraction is about 15% for a 2.5-cm-diameter pancreas. Experimental measurements verified that pO(2) is virtually zero in the core of a 1-cm-thick pancreatic piece preserved with the TLM. Penetration of solution around the sensor may be responsible for the observed lag and for the previously reported nonzero pO(2) measurements. Reoxygenation of heat-treated tissue took several hours. CONCLUSIONS: The TLM can oxygenate only a small volume fraction of a human pancreas. Pancreas oxygenation through the native vasculature should be explored to further improve yield of viable islets.

CSs and USs: what's the difference?

Differences in processing representations of conditioned and unconditioned stimuli (CSs and USs) may result from either their temporal order in training (i.e., CSs precede USs) or the greater biological significance of USs. The CS- and US-preexposure effects were used to probe this question. These effects are similar except that context extinction between preexposure and training more readily attenuates the US- than the CS-preexposure effect. In Experiments 1, 2, and 5, context extinction following preexposure to the stimulus that later served as Event 1 in Event 1-->Event 2 pairings alleviated the response deficit due to Event 1 preexposure if Event 1 was biologically significant. In Experiments 3 and 4, context extinction alleviated the response deficit due to Event 2 preexposure if Event 2 was biologically significant. Thus, biological significance and not temporal order determines how a representation will be processed.

Overshadowing and latent inhibition counteract each other: support for the comparator hypothesis.

In 4 conditioned lick suppression experiments with rats, the combined effects of latent inhibition treatment followed by overshadowing treatment were assessed as a test of the comparator hypothesis's (R.R. Miller & L.D. Matzel, 1988) explanations of overshadowing and latent inhibition. Experiments 1 and 2 confirmed the prediction of the comparator hypothesis that combined latent inhibition and overshadowing treatments attenuate the response deficit produced by either treatment alone. Furthermore, consistent with the comparator hypothesis, posttraining changes in the associative status of the putative comparator stimulus altered responding to the target conditioned stimulus (Experiment 3), and switching contexts between latent inhibition and overshadowing treatments (Experiment 4) eliminated the interaction between the latent inhibition and overshadowing treatments.

Learning to look with one eye: the use of head turn by normals and strabismics.

When asked to look through a tube, young children (normal, strabismic, monocularly enucleated) place it between the eyes, while older children turn the head or shut one eye. We videotaped 174 children (normals and strabismics, 2-17 yr of age) and 16 normal adults to find out when and why head turn occurs. In learning to look with one eye, children progressed through a sequence of four responses, categorized by age or amount of head turn. Binocular children use head turn apparently to avoid diplopia, then, most learn to shut one eye. Adults, forced to use the "non-preferred" eye, revert to turning the head.

Heme oxygenase-1 protects pancreatic beta cells from apoptosis caused by various stimuli.

BACKGROUND: Several problems can occur after allogeneic islet transplantation: primary nonfunction, rejection, and the recurrence of autoimmune disease, which involve attack by the recipient's cytokines, T cells, natural killer cells, and monocytes on the donor's beta cells, which leads to beta-cell destruction. Recent studies have revealed that loss of transplanted islets is caused mainly by apoptosis. Heme oxygenase-1 (HO-1) is one of the antiapoptotic genes up-regulated under stress conditions. The aim of this work was to investigate any mechanisms of HO-1-mediated protection of beta cells from apoptosis. METHODS: Apoptosis was assessed by comparison of viable transfected cells with and without apoptotic stimuli, and with and without HO-1 overexpression. Activation and function of p38 mitogen-activated protein kinase were determined using the specific inhibitor SB203580. RESULTS: We have shown that HO-1 mediates antiapoptotic effects in beta cells. The percentage of apoptotic cells after stimulation with tumor necrosis factor a decreased from 75% without HO-1 to 5% when HO-1 was overexpressed. Our data indicate that HO-1 acts as a signal terminator of tumor necrosis factor alpha-induced apoptosis by modulation of the p38 mitogen-activated protein kinase pathway. CONCLUSIONS: Profound cell stress that occurs in islets after transplantation, as well as at the onset of diabetes, results in beta-cell loss through apoptosis. Protection of beta cells by HO-1 improves their survival in vitro after various proapoptotic stimuli, suggesting that HO-1 suppresses one or several signaling pathways leading to apoptosis. We hypothesize that our in vitro findings can be extrapolated to the in vivo situation, and we propose that expression of HO-1 in islets may illuminate a valuable new approach to improving diabetes treatment.

Conducting exposure treatment in multiple contexts can prevent relapse.

The acquisition of anxiety disorders (e.g., phobias) is often thought to be mediated by classical conditioning processes (e.g., Wolpe, 1958, Psychotherapy by reciprocal inhibition Wolpe and Rowan, 1989, Behaviour Research and Therapy, 27, 583-585). Thus, the success of exposure therapy is possibly a consequence of extinction, and factors affecting extinction in Pavlovian conditioning are potentially relevant to clinicians who administer exposure therapy. The present experiments investigated the effects of conducting extinction in multiple contexts using rats as subjects in a conditioned suppression paradigm. In Experiment 1, subjects received conditioned stimulus (CS) and unconditioned stimulus (US) pairings in one context followed by extinction of that CS in one or three other contexts. When tested in an associatively neutral context (i.e., different from those of conditioning or extinction), rats that had received extinction in three contexts exhibited less responding to the CS than rats that had received extinction in one context. In Experiment 2, CS-US training occurred in either one or three contexts, followed by extinction of that CS in three other contexts. Testing in a neutral context revealed that rats conditioned in multiple contexts showed greater responding to the CS than rats trained in a single context. The results are discussed in the framework of memory retrieval, and the clinical implications are explored.

Analysis of patients with a cleft of the soft palate with special consideration to the problem of velopharyngeal insufficiency.

The evaluation of therapy concepts for children suffering from cleft palate is an enormous challenge in modern oral and maxillofacial surgery and related disciplines. In the present retrospective survey 1300 patients having clefts, including the soft palate, were studied with special regard to speech improvement operations. Nine hundred fifty four patients had a cleft lip, alveolus and palate and 346 patients only isolated cleft palate. In 25.6% of the patients it was necessary to perform a secondary velopharyngoplasty for speech improvement after soft palate closure. Age of the subjects at the time of operation, primary or secondary soft palate closure, and the type of clefting were not significant factors for performing subsequent velopharyngoplasty. However, significant differences with respect to the need for a secondary velopharyngoplasty after soft palate closure were found when comparing the surgical experience of the surgeons.

The impact of psychiatric comorbidity on quality of life in patients undergoing herniated disc surgery.

BACKGROUND: Recent studies examined the role of psychiatric comorbidity in the process of rehabilitation in patients undergoing herniated disc surgery. These patients suffer from physical and psychosocial complaints or symptoms, which impact their everyday life negatively and the success of rehabilitation potentially. The objectives of this study are (1) to examine the quality of life (QoL) in disc surgery patients and to compare the findings with reference data from the general German population, and (2) to investigate the impact of psychiatric comorbidity on QoL of patients undergoing herniated disc surgery. METHODS: This study consists of 305 patients aged between 18 and 55 years who took part in face-to-face interviews during their hospital stay. Psychiatric comorbidity was assessed with the Composite International Diagnostic Interview (CIDI-DIA-X). By means of the 36-Item Short-Form Health Survey (SF-36), QoL was assessed in patients undergoing herniated disc surgery with and without psychiatric comorbidity. These findings were compared with the QoL of a representative sample of the general German population. RESULTS: Compared with the general population, QoL in patients with herniated disc surgery was lower in all domains of the SF-36. Psychiatric comorbidity impacts the QoL in patients with herniated disc surgery in all SF-36 domains except "physical function". The patients with psychiatric comorbidity showed significantly lower levels of QoL in the domains "bodily pain", "vitality", "social function", "role emotional", and "mental health". CONCLUSIONS: Psychiatric comorbidity has a substantial adverse effect on QoL in patients undergoing disc surgery. Therefore, it will be necessary to diagnose psychiatric comorbidities at an early stage and to include psychosocial interventions in the treatment of herniated disc patients aimed at improving deficits in psychosocial functioning and QoL.

Limits and chances in an unfortunate course of recurrent orbital rhabdomyosarcoma.

BACKGROUND: Orbital rhabdomyosarcoma (RMS) in childhood has an excellent survival rate after chemotherapy and radiation, and mutilating surgery can often be avoided. CASE REPORT: As a rarity we present an unfortunate disease course in a child suffering from orbital embryonal RMS which did not enduringly respond to multimodal therapy including local excision and exenteration orbitae. After short intervals and despite tumor-free margins, orbital RMS recurred twice and led to an extended exenteration orbitae including the bony margins. Because of the lack of standards for adjuvant therapy in cases of recurrences after exenteration orbitae, therapy had to be restricted to a wait- and- see strategy as the only chance of tumor control. CONCLUSION: Although survival rates of orbital RMS are high, the possibility of recurrence should not be underestimated. In cases of refractory RMS, new concepts are needed to offer further chances for survival.

Preoperative predictors for the return to work of herniated disc patients.

This study assessed socio-demographic, physical, psychological, and work-related factors predicting the ability to work 6 months after operation in disc herniation patients. After nucleotomy 214 patients answered questionnaires on job satisfaction, their desire for a disability pension, preoperative sick leave, and completed the QLQ-C30, and SCL-27A questionnaires. Additionally, data on the severity of injury and duration of pain were extracted from the clinical reports. 182 patients answered the follow-up questionnaire 6 months after operation by telephone. Socio-demgraphic and psychological factors did not influence the return to work. Factors found to be related to the ability to work were job satisfaction, preoperative sick leave, pain, and the desire for a disability pension. Using multiple regression analysis, the ability to work 6 months after rehabilitation was predicted on the basis of job satisfaction, a preoperative sick leave of less than 6 weeks, and a low pain intensity preoperatively. The results are discussed with respect to their socioeconomic implications.