Use of transcranial low-intensity focused ultrasound for targeted delivery of stem cell-derived exosomes to the brain

The blood-brain barrier (BBB) presents a significant challenge for targeted drug delivery. A proposed method to improve drug delivery across the BBB is focused ultrasound (fUS), which delivers ultrasound waves to a targeted location in the brain and is hypothesized to open the BBB. Furthermore, stem cell-derived exosomes have been suggested as a possible anti-inflammatory molecule that may have neural benefits, if able to pass the BBB. In the present study, transcranial low-intensity focused ultrasound (LIFU), without the use of intravenous microbubbles, was assessed for both (1) its ability to influence the BBB, as well as (2) its ability to increase the localization of intravenously administered small molecules to a specific region in the brain. In vivo rat studies were conducted with a rodent-customized 2 MHz LIFU probe (peak pressure = 1.5 MPa), and injection of labeled stem cell-derived exosomes. The results suggested that LIFU (without microbubbles) did not appear to open the BBB after exposure times of 20, 40, or 60 min; instead, there appeared to be an increase in transcytosis of the dextran tracer. Furthermore, the imaging results of the exosome study showed an increase in exosome localization in the right hippocampus following 60 min of targeted LIFU.

Exercise intensity and lymphocyte subset apoptosis

This investigation assessed the lymphocyte subset response to increasing intensity. Participants completed an exertion test (VO(2max)), and later performed a 10-min run at 76% VO(2max), 5-min at 87%, and run to exhaustion at 100% intensity. Blood was sampled at rest, following each intensity, and 1-h post. Cell concentration, apoptosis (annexin V) and migration (CX₃CR1) were evaluated in CD4+, CD8+, and CD19+ subsets. Relative data were analyzed using 1-way ANOVA with significance at P≤0.05. Absolute changes from rest (Δ baseline) were calculated for exercise conditions. CX₃CR1 displayed relative changes 1-h post, (CD8+ Pre=58%, Post=68%, 1 h-Post=37%, P=0.04) (CD19+ Pre=1.9%, Post=3.2%, 1 h-Post=5.2%, P=0.02). No relative changes were noted for subsets and annexin V. Absolute changes revealed that CD4+/annexin V+ and CD8+/annexin V+ significantly increased at 76%,(P<0.01). Significant absolute increases were observed in CD4+/CX₃CR1 at 87% VO2max, and at 87% and 100% VO2max in CD8+/CX₃CR1 (P<0.01). Subsets respond differently with intensity with respect to cell count, and markers of apoptosis and cell migration. CD4+ and CD8+ appear to be prone to apoptosis with moderate exercise, but significant increases in migration at higher intensities suggests movement of these cells from the vasculature in postexercise measurements.

Critical appraisal of single port access cholecystectomy

BACKGROUND

Single port access (SPA) cholecystectomy is a new concept in laparoscopic surgery. A review of existing results was performed to evaluate critically the current state of SPA with specific reference to feasibility, safety, learning curve, indications and cost-effectiveness.

METHODS

All papers identified in MEDLINE until 15 February 2010 and all other relevant papers obtained from cited references were reviewed, without any language restriction. Case reports and series of fewer than three patients were excluded.

RESULTS

After selection, 24 studies including 895 patients were analysed. None was randomized. Feasibility seems to be established, with a conversion rate of 2 per cent. SPA was not standardized and there was much technical variation. The learning curve could not be determined. Median follow-up time was 3 (range 0.25-12) months. The overall published complication rate was 5.4 per cent and the biliary complication rate 0.7 per cent. The rate of umbilical complications ranged from 2 to 10 per cent.

CONCLUSION

SPA cholecystectomy seems feasible, but standardization, safety and the real benefits for patients need further assessment. Uncontrolled wide adoption of this approach may be responsible for a rise in biliary complications.

Extraction of many-body configurations from nonlinear absorption in semiconductor quantum wells

Detailed electronic many-body configurations are extracted from quantitatively measured time-resolved nonlinear absorption spectra of resonantly excited GaAs quantum wells. The microscopic theory assigns the observed spectral changes to a unique mixture of electron-hole plasma, exciton, and polarization effects. Strong transient gain is observed only under cocircular pump-probe conditions and is attributed to the transfer of pump-induced coherences to the probe.

One dimensional resonant Fibonacci quasicrystals: noncanonical linear and canonical nonlinear effects

A detailed experimental and theoretical study of the linear and nonlinear optical properties of different Fibonacci-spaced multiple-quantum-well structures is presented. Systematic numerical studies are performed for different average spacing and geometrical arrangement of the quantum wells. Measurements of the linear and nonlinear (carrier density dependent) reflectivity are shown to be in good agreement with the computational results. As the pump pulse energy increases, the excitation-induced dephasing broadens the exciton resonances resulting in a disappearance of sharp features and reduction in peak reflectivity.

Concomitant injuries are an important determinant of outcome of high-grade blunt hepatic trauma

BACKGROUND

Little is known about the clinical importance of concomitant injuries in polytraumatized patients with high-grade blunt liver injury. A retrospective single-centre study was performed to investigate the safety of non-operative management of liver injury and the impact of concomitant intra- and extra-abdominal injuries on clinical outcome.

METHODS

Some 183 patients with blunt liver injury were admitted to Berne University Hospital, Switzerland, between January 2000 and December 2006. Grade 3-5 injuries were considered to be high grade.

RESULTS

Immediate laparotomy was required by 35 patients (19.1 per cent), owing to extrahepatic intra-abdominal injury (splenic and vascular injuries, perforations) in 21 cases. The mortality rate was 16.9 per cent; 22 of the 31 deaths were due to concomitant lesions. Of 81 patients with high-grade liver injury, 63 (78 per cent) were managed without surgery; liver-related and extra-abdominal complication rates in these patients were 11 and 17 per cent respectively. Grades 4 and 5 liver injury were associated with hepatic-related and extra-abdominal complications.

CONCLUSION

Concomitant injuries are a major determinant of outcome in patients with blunt hepatic injury and should be given high priority by trauma surgeons. An algorithm for the management of blunt liver injury is proposed.

An accelerator for neural networks with pulse-coded model neurons

The labeling of features by synchronization of spikes seems to be a very efficient encoding scheme for a visual system. Simulation of a vision system with millions of pulse-coded model neurons, however, is almost impossible on the base of available processors including parallel processors and neurocomputers. A "one-to-one" silicon implementation of pulse-coded model neurons suffers from communication problems and low flexibility. On the other hand, acceleration of the simulation algorithm of pulse-coded leaky integrator neurons has proved to be straightforward, flexible, and very efficient. Thus we decided to develop an accelerator for a special version of the French and Stein neurons with modulatory inputs which are advantageous for simulation of synchronization mechanisms. Moreover, our accelerator also provides a Hebbian-like learning rule and supports adaptivity. Up to 128 K neurons with a total number of 16 M freely allocatable synapses are simulated within one system. The size of networks, however, is not at all limited by these numbers as the system may be arbitrarily expanded. Simulation speed obviously depends on the number of interconnections and on the average activity within the network. In the case of locally interconnected networks for simulation of vision mechanisms there is only a very low percentage of simultaneously active neurons: stimuli are not simultaneously presented in all orientations and at all positions of the visual field. In these cases our accelerator provides close to real-time behavior if one second of a biological neuron is simulated by 1000 time slots.

Neoadjuvant gemcitabine/cisplatin for resectable adenocarcinoma of the pancreatic head—a prospective phase I trial

15095

Background: Pancreatoduodenectomy (PD) alone was considered a standard treatment for cancer of the pancreatic head for a long time before the recent advent of adjuvant chemotherapy (CTX). Since adjuvant chemotherapy cannot be applied to all patients (pts), and neoadjuvant chemoradiation is toxic, we initiated a prospective phase II trial in August 2001 to test the safety and outcome of neoadjuvant CTX without radiation for resectable pancreatic cancer. Methods: Pts with cytologically confirmed resectable ductal adenocarcinoma of the pancreatic head were eligible for this phase II trial. Staging and restaging examinations included chest and abdominal CT-scan, endoscopic ultrasound with cytology, PET/CT and diagnostic laparoscopy. CTX consisted of four treatments of gemcitabine (1000mg/m2) and cisplatin (50mg/m2) every two weeks, and PD was planned at week 8. CA 19–9, prealbumin serum levels, and quality of life (QLQ- 30) were also determined before and after CTX. The primary study end-point was resectability based on re-staging examinations. Follow-up CT- scans were performed every six months. Results: Thirty-one pts entered this trial. Of these, 27 completed CTX and restaging until analysis. At restaging two pts had peritoneal metastases resulting in a resectability rate of 93% (25/27). No grade IV, and 7 transient grade III toxicities occurred in five pts. Median progression-free and overall survival after diagnosis were 9.2 months (95% CI 7.7–10.8) and 26.5 months (95% CI 15.2–37.7), respectively, for resected pts. After CTX, CA 19–9 serum levels were decreased by 48% (p=0.01). Moreover, the overall quality of life was increased by 24% (p=0.02). Prealbumin serum levels were abnormal in 40% of the pts on study entry, and normal in all but 89% after CTX (p=0.02). Conclusions: Neoadjuvant gemcitabine/cisplatin over two months is well tolerated and does not jeopardize resectability of adenocarcinoma of the pancreatic head. It offers several advantages including patient selection for surgery, improvements in the nutritional status and quality of life. A randomized trial comparing adjuvant and neoadjuvant+adjuvant treatment is being planned.

No significant financial relationships to disclose.

Evaluation of Sympathetic Blockade after Intrathecal and Epidural Lidocaine in Rats by Laser Doppler Perfusion Imaging

The widespread use of neuraxial anaesthesia increases the need for animal models to evaluate therapeutic prospects, mechanisms and risks of this technique. As a methodological prerequisite, we characterised the sympathetic blockade after different modes of neuraxial anaesthesia with regard to segments supplying the splanchnic region. Under haemodynamic monitoring, lidocaine 2% or saline were infused via intrathecal (10 microl), lumbar epidural (10 and 30 microl) or thoracic epidural (10 and 30 microl) catheters. Segmental spread of neuraxially infused local anaesthetic was assessed using methylene blue. Mean arterial blood pressure decreased more severely after neuraxial lidocaine in thoracic epidural (10 and 30 microl) compared to high-volume (30 microl anaesthesia animals. Determination of the sympathetic blockade by means of laser Doppler perfusion imaging was restricted to the paws due to a higher density of subcutaneous blood vessels as compared to the abdominal wall (mean +/- SD: 3.93 +/- 0.06 vs. 1.35 +/- 0.05/384 mm(2), p < 0.05). Only high-volume (30 microl) lumbar and thoracic epidural anaesthesia (10 and 30 microl) increased skin perfusion in both hind and front paws. This extensive sympathetic blockade was demonstrated to include splanchnic segments using thermography. Segmental spread of methylene blue did not closely correspond to laser Doppler findings and should be interpreted as minimum rather than exact epidural spread of local anaesthetic.

The Biostack as an approach to high LET research

By simple geometric and dosimetric arguments the advantage of an experimental approach to high LET radiation research is demonstrated. The Biostack is capable of recording individual hits of heavy ions on single biological targets. This improved method is compared with the common experimental methods for studying biological effects with high LET radiation and is suggested as an methodological improvement in fundamental research.

Painful inflammation-induced increase in mu-opioid receptor binding and G-protein coupling in primary afferent neurons

Opioids mediate their analgesic effects by activating mu-opioid receptors (MOR) not only within the central nervous system but also on peripheral sensory neurons. The peripheral analgesic effects of opioids are best described under inflammatory conditions (e.g., arthritis). The present study investigated the effects of inflammation on MOR binding and G-protein coupling of full versus partial MOR agonists in dorsal root ganglia (DRG) of primary afferent neurons. Our results show that Freund's complete adjuvant (FCA) unilateral hindpaw inflammation induces a significant up-regulation of MOR binding sites (25 to 47 fmol/mg of protein) on DRG membranes without affecting the affinity of either full or partial MOR agonists. In our immunohistochemical studies, the number of MOR-immunoreactive neurons consistently increased. This increase was mostly caused by small-diameter nociceptive DRG neurons. The full agonist DAMGO induced MOR G-protein coupling in DRG of animals without FCA inflammation (EC50 = 56 nM; relative Emax = 100%). FCA inflammation resulted in significant increases in DAMGO-induced MOR G-protein coupling (EC50 = 29 nM; relative Emax = 145%). The partial agonist buprenorphine hydrochloride (BUP) showed no detectable G-protein coupling in DRG of animals without FCA inflammation; however, partial agonist activity of BUP-induced MOR G-protein coupling was detectable in animals with FCA inflammation (EC50 = 1.6 nM; relative Emax = 82%). In behavioral studies, administration of BUP produced significant antinociception only in inflamed but not in noninflamed paws. These findings show that inflammation causes changes in MOR binding and G-protein coupling in primary afferent neurons. They further underscore the important differences in clinical studies testing peripherally active opioids in inflammatory painful conditions.

Intrapericardial urokinase irrigation and systemic corticosteroids: an alternative to pericardectomy for persistent fibrino-purulent pericarditis

A 39-year-old man was admitted for upper abdominal pain and shortness of breath. The chest roentgenogram demonstrated cardiomegaly and left lower lobe atelectasis. Echocardiography showed circumferential pericardial effusion with signs of cardiac tamponade. Pericardial biopsy and fluid analysis were consistent with fibrino-purulent pericarditis. Despite broad-spectrum antibiotics, percutaneous and subsequently surgical drainage, pericardial effusion and tamponade recurred. We report successful treatment of a non-resolving fibrino-purulent pericardial effusion by combined intrapericardial irrigation of fibrinolytics and systemic corticosteroids administration as an alternative to pericardectomy.

Radiobiological results from the Bacillus subtilis Biostack experiments within the Apollo and the ASTP space flights

In order to check the results of earlier Biostack experiments, new experimental techniques were developed for the Biostack III experiment in the Apollo-Soyuz test project (ASTP). These techniques resulted in an increased accuracy of localization down to 0.2 micrometers for the determination of the impact parameter, accompanied by an increase in the sample size available for biological investigation. In addition, colony forming ability, metabolic mutations, and mutations affecting UV- and x-ray sensitivity were rendered observable by these methods. The biological and physical results obtained so far from the evaluation of the Bacillus subtilis experiment within Biostack III confirm and extend the findings of the previous Biostack experiments. They also add to the questions about the mechanisms of action of the radiation field under investigation, since the observed effects cannot be interpreted in terms of standard concepts.

Efficacy and safety of patient-controlled opioid analgesia for acute postoperative pain. A quantitative systematic review

BACKGROUND

The usefulness of intravenous patient-controlled analgesia (PCA) with opioids for postoperative analgesia is not well defined.

METHODS

We systematically searched (MEDLINE, EMBASE, Cochrane Library, bibliographies, any language, to January 2000) for randomised trials comparing opioid-based PCA with the same opioid given intramuscularly, intravenously, or subcutaneously. Weighted mean differences (WMD) for continuous data, relative risks (RR) and numbers-needed-to-treat (NNT) for dichotomous data were calculated with 95% confidence intervals (CI) using fixed and random effects models.

RESULTS

Data from 32 trials were analysed: 22 (1139 patients) were with morphine, five (682) with pethidine, three (184) with piritramide, one (47) with nalbuphine and one (20) with tramadol. In three morphine and one pethidine trial (352 patients), more patients preferred PCA (89.7% vs. 65.8%, RR 1.41 (95%CI 1.11 to 1.80), NNT 4.2). Combined dichotomous data on pain intensity and relief, and the need for rescue analgesics from eight morphine, one pethidine, one piritramide, and one nalbuphine trial (691 patients), were in favour of PCA (RR 1.22 (1.00 to 1.50), NNT 8). In two morphine trials (152), pulmonary complications were more frequently prevented with PCA (100% vs. 93.3%, RR 1.07 (1.01 to 1.14), NNT 15). There was equivalence for cumulative opioid consumption, pain scores, duration of hospital stay, and opioid-related adverse effects.

CONCLUSION

These trials provide some evidence that in the postoperative pain setting, PCA with opioids, compared with conventional opioid treatment, improve analgesia and decrease the risk of pulmonary complications, and that patients prefer them.

Latex allergy and anaphylaxis in a child undergoing craniofacial surgery

This case report represents an example of latex anaphylaxis in a child with a history of multiple previous surgeries without any complications. Obviously, the patient had not shown evidence of being sensitized until this particular surgery, where she had multiple sources of latex exposure, e.g., Foley catheter, blood pressure cuff, rubber gloves, and clear adhesive tape. If a more careful history had been taken, the diagnosis of latex allergy might have been suspected, for upon further questioning after surgery, the mother reported multiple incidences of urticarial reactions to rubber gloves and clothes with elastic waist bands. In summary, this case report highlights the importance of a careful history and the need for a high index of suspicion of potential latex allergy in children who acquire sensitization to latex because they require multiple surgical procedures for anatomic correction of congenital abnormalities. One week after this episode, the patient returned to the operating room for completion of her surgery. All latex was avoided, and there were no complications.

Expression of corticotropin-releasing factor in inflamed tissue is required for intrinsic peripheral opioid analgesia

Immune cell-derived opioid peptides can activate opioid receptors on peripheral sensory nerves to inhibit inflammatory pain. The intrinsic mechanisms triggering this neuroimmune interaction are unknown. This study investigates the involvement of endogenous corticotropin-releasing factor (CRF) and interleukin-1beta (IL-1). A specific stress paradigm, cold water swim (CWS), produces potent opioid receptor-specific antinociception in inflamed paws of rats. This effect is dose-dependently attenuated by intraplantar but not by intravenous alpha-helical CRF. IL-1 receptor antagonist is ineffective. Similarly, local injection of antiserum against CRF, but not to IL-1, dose-dependently reverses this effect. Intravenous anti-CRF is only inhibitory at 10(4)-fold higher concentrations and intravenous CRF does not produce analgesia. Pretreatment of inflamed paws with an 18-mer 3'-3'-end inverted CRF-antisense oligodeoxynucleotide abolishes CWS-induced antinociception. The same treatment significantly reduces the amount of CRF extracted from inflamed paws and the number of CRF-immunostained cells without affecting gross inflammatory signs. A mismatch oligodeoxynucleotide alters neither the CWS effect nor CRF immunoreactivity. These findings identify locally expressed CRF as the predominant agent to trigger opioid release within inflamed tissue. Endogenous IL-1, circulating CRF or antiinflammatory effects, are not involved. Thus, an intact immune system plays an essential role in pain control, which is important for the understanding of pain in immunosuppressed patients with cancer or AIDS.

Palliation of carcinoma of the oesophagus with brachytherapy and the Didcott dilator

Forty-one patients with oesophageal cancer who developed strictures after high dose rate intraluminal brachytherapy were dilated using a slow continuous dilator (Didcott dilator). After dilatation, all patients were evaluated monthly for relief of dysphagia. At the end of the 1st month, 41 patients were evaluable: 28 had no dysphagia while 13 had improvement; at the end of the 2nd month, 40 were evaluable, 26 had no dysphagia while 14 had improvement; at the end of the 3rd month, 34 patients were evaluable, 24 had no dysphagia while 10 had improved. Three patients developed worsening of dysphagia owing to tumour recurrence among 32 patients who were evaluable at the end of the 4th month. Five patients developed worsening of dysphagia among the 26 patients who were evaluable at the 5th month due to tumour. These patients were dilated with the Didcott dilator and were treated with further brachytherapy. At the end of the 6th month, 14 patients were evaluable; seven had no dysphagia, while seven had improvement over their presenting dysphagia scores. Slow continuous dilatation using the Didcott dilator is very effective in the dilatation of strictures after high dose rate intraluminal brachytherapy. Dilatation is prolonged and sustained and a single dilatation is usually enough to maintain patency.

Effects of heavy ions on inactivation and DNA double strand breaks in Deinococcus radiodurans R1

Inactivation and double strand break (dsb) induction after heavy ion irradiation were studied in stationary phase cells of the highly radiation resistant bacterium Deinococcus radiodurans R1. There is evidence that the radiation sensitivity of this bacterium is nearly independent on energy in the range of up to 15 MeV/u for lighter ions (Ar). The responses to dsb induction for charged particles show direct relationship between increasing radiation dose and residual intact DNA.

Heavy ion induced DNA double strand breaks in cells of E. coli

Vegetative cells of E. coli differing in their radiosensitivity have been used in heavy ion irradiation experiment. Besides inactivation measurements also the induction of DNA double strand breaks (DSB) have been measured using the method of pulse-field gel electrophoresis. This method allows to separate linear DNA with length up to 8 Mio base pairs. After irradiation with heavy ions we find a higher amount of low molecular weight fragments when compared to sparsely ionizing radiation. This agrees with the idea that heavy ions as a structured radiation have a high probability to induce more than one strand break in a DNA molecule if the particle hits the DNA. The amount of intact DNA remaining in the agarose plugs decreases exponentially for increasing radiation doses or particle fluences. From these curves cross sections for the induction of DSB after heavy ion irradiation have been determined. These results will be discussed in comparison to the results for cell survival.

Inactivation of individual Bacillus subtilis spores in dependence on their distance to single accelerated heavy ions

In order to understand radiation mechanisms of heavy ions in detail, it is necessary to study effects of single ions on individual biological test objects. Spores of Bacillus subtilis have been used as a suitable small biological test system to measure the inactivation in dependence on the radial distance to the tracks of charged particles. Accelerator experiments have been performed using a modified Biostack technique--biological objects sandwiched between nuclear track detectors. Results of these experiments using ions differing in their energy and atomic number will be discussed under following aspects: (i) methodological differences between the experiments and their possible influences on the results, (ii) common features which are independent on the particle type and energy, (iii) theoretical expectations and problems to find solid theoretical concepts which explain the results.

Inactivation of individual Bacillus subtilis spores in dependence on their distance to single cosmic heavy ions

For radiobiological experiments in space, designed to investigate biological effects of the heavy ions of the cosmic radiation field, a mandatory requirement is the possibility to spatially correlate the observed biological response of individual test organisms to the passage of single heavy ions. Among several undertakings towards this goal, the BIOSTACK experiments in the Apollo missions achieved the highest precision and therefore the most detailed information on this question. Spores of Bacillus subtilis as a highly radiation resistant and microscopically small test organism yielded these quantitative results. This paper will focus on experimental and procedural details, which must be included for an interpretation and a discussion of these findings in comparison to control experiments with accelerated heavy ions.

Longitudinal assessment of mental development in infants with nonsyndromic craniosynostosis with and without cranial release and reconstruction

The effect of cranial release and reconstruction on the mental development of infants with nonsyndromic craniosynostosis was evaluated. Longitudinal assessment of mental development for infants before and after cranial release and reconstruction and for infants not undergoing surgical treatment was obtained by using the mental scale of the Bayley Scales of Infant Development. Severity of anatomic craniofacial deformity, perinatal medical risk factors, and age at time of surgery also were investigated. None of the infants displayed mental retardation [Mental Development Index (MDI) score < 70] before or after cranial release and reconstruction. Scores ranged from borderline retardation to very superior following a normal distribution. Severity of anatomic craniofacial deformity and perinatal risk factors were unrelated to mental development. Cranial release and reconstruction did not affect mental development positively or negatively but did result in improvement of the original craniofacial deformity.

Altered ratios of beta-endorphin:beta-lipotropin released from anterior lobe corticotropes with increased secretory drive. II. Repeated stress

A number of stimuli including acute footshock and electrically-induced seizures lead to release of beta-endorphin immunoreactivity from the anterior pituitary corticotropes. Gel filtration of this beta-endorphin immunoreactivity indicates that approximately 3-fold more beta-endorphin than beta-lipotropin is released into plasma following these acute stressors. A similar preponderance of beta-endorphin over beta-lipotropin is seen in the media of short-term anterior lobe cell suspensions stimulated with ovine corticotropin-releasing hormone. Previous studies indicated that footshock stress, when administered repeatedly, can increase the biosynthesis of anterior lobe proopiomelanocortin (POMC) as indicated by increased steady state adrenocorticotropin/beta-endorphin content as well as increased POMC mRNA levels and increased POMC biosynthesis and rate of processing as measured by pulse-labeling and pulse-chase studies. The goal of the present studies was to determine whether this increased biosynthetic drive results in an alteration in the end products secreted with repeated stress. Acute footshock in a rat which has received 14 days of chronic footshock releases proportionately more beta-lipotropin than is released in a naive rat. Chronic electrically-induced seizures, which also increase anterior lobe POMC derived peptide stores, lead to a similar shift in the ratio of beta-lipotropin:beta-endorphin released following stress. These data suggest that chronic drive and the subsequent changes in POMC peptide stores may lead to a decrease in the proportion of beta-endorphin size immunoreactivity in the releasable pool of the anterior lobe corticotrope, thus altering the hormonal signal from the anterior lobe corticotrope.

Laser in situ monitoring of combustion processes

Several examples of laser in situ monitoring of combustion processes are presented. Using a frequency modulated (13)CO(2) waveguide laser, in situ concentrations of NH(3) down to 1 ppm were measured at temperatures up to 600 degrees C in waste incinerators and power or chemical plants. Following ignition of CH(3)OH-O(2) mixtures by a TEA CO(2) laser, gas temperature profiles were measured using rapid scanning tunable diode laser spectroscopy of CO molecules. In laminar CH(4)-air counterflow diffusion flames at atmospheric pressure absolute concentrations, temperatures, and collisional lifetimes of OH radicals were determined by 2-D and picosecond LIF and absorption spectroscopy. Two-dimensional LIF and Mie scattering were used to observe fuel injection and combustion in a diesel engine.

Cell inactivation, repair and mutation induction in bacteria after heavy ion exposure: results from experiments at accelerators and in space

To understand the mechanisms of accelerated heavy ions on biological matter, the responses of spores of B. subtilis to this structured high LET radiation was investigated applying two different approaches. 1) By the use of the Biostack concept, the inactivation probability as a function of radial distance to single particles' trajectory (i.e. impact parameter) was determined in space experiments as well as at accelerators using low fluences of heavy ions. It was found that spores can survive even a central hit and that the effective range of inactivation extends far beyond impact parameters where inactivation by delta-ray dose would be effective. Concerning the space experiment, the inactivation cross section exceeds those from comparable accelerator experiments by roughly a factor of 20. 2) From fluence effect curves, cross sections for inactivation and mutation induction, and the efficiency of repair processes were determined. They are influenced by the ions characteristics in a complex manner. According to dependence on LET, at least 3 LET ranges can be differentiated: A low LET range (app. < 200 keV/micrometers), where cross sections for inactivation and mutation induction follow a common curve for different ions and where repair processes are effective; an intermediate LET range of the so-called saturation cross section with negligible mutagenic and repair efficiency; and a high LET range (>1000 keV/micrometers) where the biological endpoints are majorly dependent on atomic mass and energy of the ion under consideration.

Prevention of chymopapain anaphylaxis by screening chemonucleolysis candidates with cutaneous chymopapain testing

With chymopapain at a concentration of 10 mg/ml, the authors skin tested 540 chemonucleolysis candidates; six were positive, and 534 were negative. None of the positive patients received therapeutic injections of chymopapain. There were no instances of unequivocal anaphylaxis to chymopapain in the patients with negative skin tests treated with chymopapain. When this 0% incidence of systemic reactions in skin test negative patients is compared with the historical rate of 1%, this difference is statistically significant (p less than 0.05). Restriction of chymopapain treatment to patients with negative prick tests can reduce the incidence of systemic reactions.

Prevention of chymopapain anaphylaxis by screening chemonucleolysis candidates with cutaneous chymopapain testing. A preliminary report

The risk of anaphylaxis in candidates for chemonucleolysis for herniated lumbar discs is approximately 1%. An investigation was designed to eliminate or reduce the incidence of chymopapain anaphylaxis. The procedure was to restrict chemonucleolysis to patients who are prick test-negative to chymopapain at a concentration of 10 mg/ml. The authors skin-tested 292 chemonucleolysis candidates; five were positive and 287 were negative. None of the positive patients were injected with chymopapain. There were no instances of unequivocal chymopapain anaphylaxis in the skin test-negative group. This 0% incidence of anaphylaxis in skin test-negative patients was compared with a population estimate of 1%, based on historical data. The resulting value of p = 0.08 value fell short of the conventional level of significance of 0.05. The p value will reach 0.05 when the series of skin test-negative patients without anaphylaxis reaches 360. It is important that this information is readily available to physicians concerned about anaphylactic reactions to chymopapain.

CT and MRI of orbital abnormalities in neurofibromatosis and selected craniofacial anomalies

This article begins with a discussion of normal orbital anatomy and the terminology involved in the description of abnormalities of the orbit. Case reports of patients with neurofibromatosis or with a craniofacial anomaly are presented, and the characteristic orbital findings on both CT and MRI are reviewed. Thus the radiologist's role and the value of CT and MRI in the overall treatment of these often complex abnormalities are elucidated.

Genetic response of bacterial spores to very heavy ions

Using spores of two Bacillus subtilis strains differing in repair capacity, we have studied repair and mutation induction in the spores after irradiation with very heavy ions up to uranium with specific particle energies up to 18.6 MeV/u. The results indicate that repair and mutation induction after heavy ion irradiation are closely related to each other and that both phenomena strongly depend on the atomic number and specific energy of the ions. The effects are discussed in comparison with results obtained after X-irradiation.

Advanced biostack: experiment 1 ES 027 on Spacelab-1

The radiobiological properties of the heavy ions of cosmic radiation were investigated on Spacelab 1 by use of biostacks, monolayers of biological test organisms sandwiched between thin foils of different types of nuclear track detectors. Biostacks were exposed to cosmic radiation at several locations with different shielding environments in the module and on the pallet. Evaluations of the physical and biological components of the experiment to date indicate that in general they survived the spaceflight in good condition. Dosimetric data are presented for the different shielding environments.

Unique radiobiological aspects of high-LET radiation

Since the beg inning of manned space flight the potentially unique radiobiological properties of the heavy ions of the cosmic radiation had been, apart from possible interactions of radiation effects with biological effects of weightlessness, of major concern with respect to the assessment of radiation hazards in manned space flight. Radiobiological findings obtained from space flight experiments and ground based experiments with densely ionizing radiation are discussed, which suggest qualitative differences between the radiobiological mechanisms of sparsely ionizing and densely ionizing radiation. These findings comprise the observation of a long lateral range of radiobiological effectiveness around tracks of single heavy ions, the observation of micro lesions induced in biological targets by the penetration of heavy ions, the nonadditivity of radiobiological effects from sparsely and densely ionizing radiation, the different kinetics for the expression of late effects induced by sparsely or densely ionizing radiation, and the observation of a reversed dose rate effect for early and late effects induced by densely ionizing radiation. These findings bear on the radiation protection standards to be installed for a general public in manned space flight and on the design of experiments, which intend to contribute to their specification.

Restriction sites containing CpG show a higher frequency of polymorphism in human DNA

Unique loci in the human genome were examined with restriction enzymes in order to detect restriction fragment length polymorphisms (RFLPs). Of 31 arbitrary loci, nine were detectably polymorphic, reflecting ten polymorphic restriction sites. Nine of the ten polymorphic sites were revealed with two restriction enzymes, Msp I and Taq I, whose recognition sequences have in common the dimer sequence CpG. The cytosines in the CpG sequence are known to be frequently methylated in mammals, and the occurrence of significant variation in Msp I and Taq I sites supports the view that methylated cytosine residues are hotspots for mutation in mammalian DNA.

Inactivation probability of heavy ion-irradiated Bacillus subtilis spores as a function of the radial distance to the particle's [correction of paricle's] trajectory

The understanding of the radiobiological action of heavy ions requires the knowledge of the dependence of the inactivation probability on the distance between the particle's trajectory and the biological test organism (the impact parameter). Spores of Bacillus subtilis with a cytoplasmic core of about 0.22 micrometer cross section are suitable test objects for the study of this radial inactivation probability in its microscopic details. The spores are irradiated at low fluences of some 10(6) ions/cm2 with very heavy ions at different specific energies up to 10 MeV per atomic mass unit u while in fixed contact with visual nuclear track detectors. The methods are described by which the biological response of individual cells can be evaluated and the impact parameter be determined with an accuracy typically better than 0.2 micrometer. The results demonstrate that the common characteristics of inactivation, e.g., an effective range of inactivation extending to at least 3 micrometers, a nonmonotonic dependence of the inactivation probabilities on the radial distance, and the fact that the inactivation probability even for direct central hits on the cytoplasmic core is substantially below one, are nearly independent of the particle energy and type. The results are incompatible with the assumption that the radiobiological effectiveness can be attributed to the dose of secondary electrons as currently understood. They also demonstrate that the widely held notion of an "overkill" at low impact parameters does not apply for the spores even with the most densely ionizing ions.