Temporally versatile polarization entanglement from Bragg reflection waveguides.

Bragg reflection waveguides emitting broadband parametric downconversion (PDC) have been proven to be well suited for the on-chip generation of polarization entanglement in a straightforward fashion [Sci. Rep.3, 2314 (2013)SRWSDA2045-232210.1038/srep02314]. Here, we investigate how the properties of the created states can be modified by controlling the relative temporal delay between the pair of photons created via PDC. Our results offer an easily accessible approach for changing the coherence of the polarization entanglement, in other words, to tune the phase of the off-diagonal elements of the density matrix. Furthermore, we provide valuable insight into the engineering of these states directly at the source.

Uncovering dispersion properties in semiconductor waveguides to study photon-pair generation.

We investigate the dispersion properties of ridge Bragg-reflection waveguides to deduce their phasematching characteristics. These are crucial for exploiting them as sources of parametric down-conversion (PDC). In order to estimate the phasematching bandwidth we first determine the group refractive indices of the interacting modes via Fabry-Perot experiments in two distant wavelength regions. Second, by measuring the spectra of the emitted PDC photons, we gain access to their group index dispersion. Our results offer a simple approach for determining the PDC process parameters in the spectral domain, and provide important feedback for designing such sources, especially in the broadband case.

Intraventricular injection of 6-hydroxydopamine results in an increased number of tyrosine hydroxylase immune-positive cells in the rat cortex.

Previously we have demonstrated that intraventricular injection of 6-hydroxydopamine (6-OHDA) results in increased proliferation and de-differentiation of rat cortical astrocytes into progenitor-like cells 4 days after lesion (Wachter et al., 2010). To find out if these cells express tyrosine hydroxylase (TH), the rate-limiting enzyme in the catecholamine synthesis pathway, we performed immunohistochemistry in the rat cortex following intraventricular injection of 6-OHDA. Four days after injection we demonstrated a strong emergence of TH-positive (TH(+)) somata in the cortices of 6-OHDA-lesioned animals. The number of TH(+) cells in the cortex of 6-OHDA-lesioned animals was 15 times higher than in sham-operated animals, where virtually no TH(+) somata occurred. Combining TH immunohistochemistry with classical Nissl stain yielded complete congruency, and ∼45% of the TH(+) cells co-expressed calretinin, which indicates an interneuron affiliation. There was no co-staining of TH with other interneuron markers or with glial markers such as glial fibrillary acidic protein (GFAP) or the neural stem/progenitor marker Nestin, nor could we find co-localization with the proliferation marker Ki67. However, we found a co-localization of TH with glial progenitor cell markers (Sox2 and S100ß) and with polysialylated-neural cell adhesion molecule (PSA-NCAM), which has been shown to be expressed in immature, but not recently generated cortical neurons. Taken together, this study seems to confirm our previous findings with respect to a 6-OHDA-induced expression of neuronal precursor markers in cells of the rat cortex, although the TH(+) cells found in this study are not identical with the potentially de-differentiated astrocytes described recently (Wachter et al., 2010). The detection of cortical cells expressing the catecholaminergic key enzyme TH might indicate a possible compensatory role of these cells in a dopamine-(DA)-depleted system. Future studies are needed to determine whether the TH(+) cells are capable of DA synthesis to confirm this hypothesis.

Prospective, randomized-controlled trial comparing postoperative pain after plug and patch open repair with totally extraperitoneal inguinal hernia repair.

PURPOSE: The aim of this study was to compare postoperative pain between the open tension-free plug and patch (PP) technique and the totally extraperitoneal patch (TEP) hernioplasty. METHODS: One hundred and fifty-four male patients with unilateral inguinal hernia were randomized to undergo PP and TEP from 2005 to 2009. Pain assessment was conducted using the numerical rating scale (NRS) and the McGill Pain Questionnaire preoperatively, 6, 12 and 24 months postoperatively. All patients received the same analgesic regimen and documented pain in a NRS-based 4-week diary. RESULTS: Of the 154 patients 77 underwent TEP and 77 PP. Median follow-up was 3.8 years. One recurrent hernia was observed in the TEP and two in the PP group (p = 0.56). Median preoperative NRS scores were 2 and 2, 0.3 and 0.4 at 6 months, 0.1 and 0.3 at 12 months, 0.2 and 0.1 at 24 months postoperatively in the PP and TEP groups, respectively (p > 0.05). Data from the 4-week pain diaries revealed significant differences in pain intensity between the two different techniques from the second postoperative week (p < 0.05). Patients in the PP group required more additional analgesics on day four and five postoperatively (p = 0.037 and 0.015, respectively). CONCLUSIONS: Our data favor the TEP technique concerning postoperative pain as primary endpoint between tension-free PP and TEP hernia repair.

Trans-fascial laparoscopic mesh fixation: a procedural comparison using the standard suture passer versus iMESH stitcher™ device.

INTRODUCTION: Laparoscopic mesh repair has become an increasingly common method for repairing incisional hernias. The current method for fixating mesh to the abdominal wall includes tacking the mesh to the peritoneum and fascia and suturing the mesh to the fascia with trans-fascial sutures. The iMESH Stitcher™ is a stitching device developed to both simplify and expedite this procedure by passing the suture from one arm of the iMESH stitcher™ to the other. The device enables a stitch to be created in three quick moves using only one hand. We compared both the efficacy and procedure time of trans-fascial mesh fixation when performed with the iMESH stitcher™ as compared to the standard suture passer method. METHODS: A mesh patch was installed on the internal abdominal wall of two pigs. Surgical residents and Medical students were participants in the study and were trained in both techniques. Each participant was asked to perform six fixations with each technique. The procedural time required for both fixation techniques was recorded. Participants were asked to assess subjectively the relative difficulty of each technique on a scale of 1-10 (10 = most difficult). RESULTS: Sixteen residents and students performed a total of 12 mesh fixations, each performing 6 fixations with each technique. Average mesh fixation suture time using the suture passer technique was 44 s for residents and 47 s for students. Average fixation suture time using the iMESH stitcherTM was 17 s for residents and 15 s for students. The average difficulty score for the suture passer technique was 6.1 as compared to 2.9 with iMESH stitcher™. CONCLUSION: Trans-fascial fixation with the iMESH Stitcher™ took significantly less time than the standard suture passer method. The iMESH Stitcher™ significantly simplifies the procedure of transfascial fixation and potentially reduces technical difficulties.

Use of surface acoustic waves to reduce pain and discomfort related to indwelling nasogastric tube.

BACKGROUND AND STUDY AIMS: Nasogastric intubation, one of the most widely utilized therapeutic procedures in medical practice, is associated with trauma, pain, and discomfort, which can occur both at insertion and during the indwelling phase. Although lubricating jelly is useful during the insertion phase, insertion can still cause great discomfort. Furthermore, the jelly is rapidly absorbed and therefore is unable to decrease the friction between the tissues and the tube during the indwelling phase of the nasogastric tube. The aim of this study was to test a device, the NG-Shield, that generates surface acoustic waves on the surfaces of the nasogastric tube to reduce contact time and thus friction between the nasogastric tube and body tissues. PATIENT AND METHODS: Twenty-four healthy volunteers were enrolled in a single-center, crossover, blinded study, in which a nasogastric tube was inserted and left indwelling for 6 hours. Throughout the indwelling period the device was activated and deactivated alternately every hour, and the volunteers were questioned every hour about their pain and discomfort levels as well as grading pain and discomfort upon insertion and removal of the nasogastric tube. Pain and discomfort levels were compared between active and nonactive phases of the device. RESULTS: The activated NG-Shield was found to reduce both pain and discomfort significantly in both the nose and throat throughout the indwelling phase. CONCLUSIONS: The NG-Shield is a safe and effective device for reducing pain and discomfort associated with an indwelling nasogastric tube.

Neuropathic pain after femoropopliteal bypass surgery.

OBJECTIVE: This retrospective study was performed to investigate prolonged postoperative pain in the area of the proximal or distal scar or the bypass tunnel after femoropopliteal bypass surgery to treat symptomatic peripheral arterial disease. PATIENTS AND METHODS: Ninety-three patients with peripheral arterial disease who underwent femoropopliteal bypass surgery between January 2000 and December 2002 were included in the study. The short-form McGill Pain Questionnaire was used to score pain. Ultrasound examination of the soft tissue around the graft was performed to exclude other pathologic conditions responsible for pain, such as inflammatory processes, perigraft reactions, swollen lymph nodes, and hematomas. RESULTS: Pain in at least one scar existed in 22 patients on average 13.9 +/- 9.8 months after surgery. In 10 patients pain existed simultaneously along the inguinal scar and the above-knee or below-knee scar. Pain along the bypass tunnel was experienced by seven patients. Most patients had mild to moderate pain. The mean numeric ranking score of pain severity in patients with pain was 4.2 +/- 2.3. The occurrence of prolonged postoperative pain was not associated with age, gender, diabetes, indication for surgery, material or type of bypass, number of preceding operations, or postoperative wound complications. Only follow-up time after femoropopliteal bypass surgery tended to be lower in patients with pain compared with those without pain. CONCLUSION: Prolonged postoperative neuropathic pain along the distal and proximal incision or the bypass tunnel exists in one fourth of patients after femoropopliteal bypass surgery. Patients should be informed of this kind of complication before surgery. The results of our study justify further investigations of the origin and treatment of this pain, to find effective methods to reduce the incidence of prolonged postoperative pain after femoropopliteal bypass surgery.

Modulatory effects on human sensorimotor cortex by whole-hand afferent electrical stimulation.

OBJECTIVE: To investigate the effect of electrical stimulation of the nerve afferents of the hand on cortical activity elicited by whole-hand subthreshold stimulation for sensation in healthy human subjects. METHODS: Ten healthy volunteers were studied using BOLD-fMRI with 1) a test motor-task with finger-to-thumb tapping of the left hand, 2) a whole-hand afferent electrical stimulation of the left hand below the sensory level for sensation for 30 minutes, 3) a second fMRI run with the same paradigm as in the test motor-task immediately after electrical stimulation, and 4) a final identical fMRI run 2 hours post-stimulation to test the cortical changes induced by electrical stimulation. Experiments were carried out on a 1.5 T MR scanner and for fMRI echoplanar sequences were used. Data analysis was performed with SPM99. RESULTS: An increase of movement-related responses was seen within the primary motor and primary somatosensory areas of both hemispheres when comparing the test motor-task with the motor-task after electrical stimulation relative to the baseline or sham stimulation. Two hours post-stimulation the modulatory effects of mesh-glove stimulation diminished to baseline level except within the contralateral primary motor region. CONCLUSIONS: The increased BOLD response spatially localized within the sensorimotor cortex reflects an increase in neuronal activity that may provide augmented neuronal excitability.

Prospective randomized trial using laser acupuncture versus desmopressin in the treatment of nocturnal enuresis.

OBJECTIVES: Several treatment modalities for children suffering from monosymptomatic nocturnal enuresis are available, but desmopressin is a well-established option. On the other hand, alternative nonpharmacological therapies such as laser acupuncture are more frequently requested by the parents. To our knowledge, there is no prospective randomized trial which evaluated the efficacy of such an alternative approach in comparison with the widespread use of desmopressin. METHODS: Forty children aged over 5 years presenting with primary nocturnal enuresis underwent a previous evaluation of their voiding function to assure normal voiding patterns and a high nighttime urine production. Then the children were randomized into two groups: group A children were treated with desmopressin alone, and group B children underwent laser acupuncture. All children were investigated after a minimum follow-up period of 6 month to evaluate the duration of the response. RESULTS: The children of both groups had an initial mean frequency of 5.5 wet nights per week. After a minimum follow-up period of 6 months reevaluation revealed a complete success rate of 75% in the desmopressin-treated group. Additional 10% of the children had a reduction of their wet nights of more than 50%. On the other hand, 6 months after laser acupuncture, 65% of the randomized children were completely dry. Another 10% had a reduction of the enuresis frequency of more than 50% per week. 20% of the children in the desmopressin-treated group did not respond at all as compared with 15% in the acupuncture-treated group. Statistical evaluation revealed no significant differences among the response rates in both groups. CONCLUSION: Im comparison with pharmacological therapy using desmopressin, our study shows that laser acupuncture should be taken into account as an alternative, noninvasive, painless, cost-effective, and short-term therapy for children with primary nocturnal enuresis in case of a normal bladder function and high nighttime urine production. Success rates indicated no statistically significant differences between the well-established desmopressin therapy and the alternative laser acupuncture.

Korean hand acupressure reduces postoperative vomiting in children after strabismus surgery.

A double-blind, randomized, placebo-controlled study was conducted to investigate the effectiveness of Korean hand acupuncture in preventing postoperative vomiting in children scheduled for strabismus surgery. In one group, acupressure was performed 30 min before induction of anaesthesia by applying an acupressure disc onto the Korean hand acupuncture point K-K9; the disc remained in situ for at least 24 h. The second group functioned as placebo group. The treatment groups did not differ with regard to patient characteristics, surgical procedure and anaesthetic administered. In the acupressure group, the incidence of vomiting was significantly lower (20%) than in the placebo group (68%). We conclude that Korean hand acupressure of the acupuncture point K-K9 is an effective method for reducing postoperative vomiting in children after strabismus repair.

Low-power laser light in the healing of burns: a comparison between two different wavelengths (635 nm and 690 nm) and a placebo group.

BACKGROUND AND OBJECTIVE: Studies on the influence of low-power laser light on wound healing have shown inconsistent results, or, as in the case of burns, are very scarce. We have studied the effects of two different low-power diode laser lights on the healing of burns in rats. STUDY DESIGN/MATERIALS AND METHODS: Thirty rats were burned on both flanks and randomly allocated to one of three study groups. In group A, both wounds remained untreated; in groups B and C, one wound each was irradiated with 635 nm or 690 nm laser light (1.5 J/cm(2)), whereas the other wound remained untreated. Diameter, redness, and edema of the wounds were examined daily. RESULTS: Between and within groups, diameter, redness, and edema of the wounds were similar throughout the entire observation period. Irradiation of the burns did not accelerate wound healing when compared with control wounds. CONCLUSION: We conclude that neither 690 nm nor 635 nm low-power laser light produced any beneficial effects on the healing processes of burns in rats.

Exogenous neopterin causes cardiac contractile dysfunction in the isolated perfused rat heart.

Neopterin is known in humans as a sensitive marker for diseases associated with increased activity of the cellular immune system. Recent studies report neopterin also to exhibit distinct effects: neopterin induces inducible nitric oxide synthase expression in rat vascular smooth muscle cells and activates translocation of nuclear factor- kappa B. Neopterin may also induce oxidative stress causing apoptotic cell death, or superinduce tumor necrosis factor- alpha -mediated apoptosis. Observing these effects in cell cultures, we were interested in possible consequences of neopterin on cardiac function in the isolated perfused rat heart. The influence of neopterin in three different concentrations (10 micromol/l, 50 micromol/l, 100 micromol/l) on cardiac contractility parameters and coronary vascular resistance were studied in 67 male Sprague-Dawley rats using the temperature-controlled and pressure-constant Langendorff apparatus with retrograde perfusion of the aorta with a Krebs-Henseleit buffer. Treatment with 100 micromol/l neopterin resulted in a significant decrease in coronary flow and cardiac contractility. Coronary flow decreased from 15.2 to 9.5 ml/min (P=0.002), left ventricular pressure from 80 to 52 mmHg (P=0. 002), rate of pressure fall from 1605 to 923 mmHg/s (P=0.001) and rate of pressure rise from 2862 to 1709 mmHg/s (P=0.001). Concentrations lower than 100 micromol/l neopterin had no significant effect on cardiac function. Our study demonstrates a considerable influence of exogenous neopterin on cardiac performance in the Langendorff model of isolated perfused rat hearts. This has to be considered a potential pathogenic factor of cardiac disturbances in diseases in which high concentrations of neopterin are released due to immune activation. At present the exact mechanism remains unclear.

Rectally administered dimenhydrinate reduces postoperative vomiting in children after strabismus surgery.

We have investigated the effectiveness of rectally administered dimenhydrinate on postoperative vomiting in children undergoing strabismus surgery, in a double-blind, randomized, placebo-controlled study. In one group, dimenhydrinate 50 mg was administered rectally 30 min before starting anaesthesia, whereas in the control group, placebo suppositories were given. Children who received dimenhydrinate showed a significantly (P < 0.001) lower incidence of vomiting (15%) than those in the control group (75%). We conclude that rectal administration of dimenhydrinate is an effective means of reducing postoperative vomiting in children undergoing strabismus surgery.

Healing of burns after treatment with 670-nanometer low-power laser light.

Recent investigations have reported contradictory results on the influence of low-power laser light on wound healing. Low-power laser with a power output of 250 mW and an emitted laser light of 670 nm have been insufficiently investigated to date. The effect of a 250-mW/670-nm laser light on the healing of burning wounds in rats was investigated. Thirty rats were burned on both flanks. One wound was irradiated with 670-nm laser light (2 J/cm2), whereas the other side remained untreated. Macroscopic evaluation of the wounds was performed daily; 10, 20, and 30 days after burning, 10 rats were killed and the wounds histologically evaluated. Neither macroscopic nor histologic examination of the irradiated wound showed accelerated wound healing when compared with control wounds. In the present study, irradiation of burns with a 250-mW/670-nm laser light produced no beneficial effects on wound-healing processes.

Oxygen application by a nasal probe prevents hypoxia but not rebreathing of carbon dioxide in patients undergoing eye surgery under local anaesthesia.

BACKGROUND/AIM: Hypoxia and carbon dioxide rebreathing are potential problems during eye surgery in spontaneously breathing patients. The aim of the present study was to determine effectiveness of nasal application of oxygen to prevent hypoxia and carbon dioxide accumulation in spontaneously breathing patients undergoing cataract surgery. METHODS: Oxygenation and carbon dioxide rebreathing were examined in 40 elderly patients using two different methods of oxygen supply-nasal v ambient air-with a constant flow of 2 l/min. Partial pressure of carbon dioxide under ophthalmic drapes, transcutaneous pressure of carbon dioxide, and the respiratory rate were measured during 25 minutes while oxygen was supplied via a nasal cannula or into the ambient air under the drapes. RESULTS: In both groups carbon dioxide accumulation under the drapes, carbon dioxide rebreathing, tachypnoea, and an increase in peripheral oxygen saturation occurred. No significant differences were found between the two methods. CONCLUSION: Nasal application of oxygen prevented hypoxia but did not prevent carbon dioxide accumulation in patients undergoing eye surgery under retrobulbar anaesthesia. Additionally, as a side effect when using nasal probes, irritation of the nose was described in half of the patients investigated.

Heat trapped under paper and plastic ophthalmic drapes during eye surgery using local anesthesia.

PURPOSE: To assess whether heat trapped under ophthalmic drapes is responsible for patient reports of being hot during cataract surgery using local anesthesia. SETTING: Departments of Anaesthesia and Intensive Care Medicine and of Ophthalmology and Optometry, Innsbruck University Hospital, Innsbruck, Austria. METHODS: In a prospective, randomized, single-blind study, the temperature in the ambient air under 2 types of paper drapes (Group A: Barrier Ophthalmology Drape, Johnson & Johnson; Group B: Steri Drape 1062, 3M) and a plastic drape (Group C: cotton drape + Steri Drape 1024, 3M) was measured for 25 minutes in 60 patients having cataract surgery under local anesthesia. RESULTS: Three minutes after the patient's head was draped, the mean temperature under the drape began to increase significantly: Group A, 25.7 degrees C +/- 0.3 degree C (SD) to 29.17 degrees C +/- 0.9 degree C (P < or = .001); Group B, 25.87 degrees C +/- 0.4 degree C to 29.41 degrees C +/- 0.9 degree C (P < or = .001); Group C, 25.8 degrees C +/- 0.35 degree C to 29.4 degrees C +/- 0.6 degree C (P < or = .001). It continued to increase in all groups as the operation continued. No significant differences in temperature were observed among the 3 drape types studied. Subjective thermal discomfort was reported by 35% to 40% of patients. CONCLUSION: Paper drapes did not cause less heat from being trapped than the plastic drape. Trapped heat may impair the comfort of patients having eye surgery under local anesthesia.

New support for ophthalmic drapes.

A new flexible support for ophthalmic drapes with the possibility of continuous oxygen supplementation was designed for use in patients undergoing eye surgery under local anesthesia. This new equipment is easy to handle and prevents contact between the patient's face and the ophthalmic drape. To prevent hypoxia of spontaneously breathing patients, the ambient air under the drapes can be supplemented with oxygen using this new equipment and no other devices. The equipment described here is advantageous for practical use in patients undergoing eye surgery under retrobulbar anesthesia.

New equipment to prevent carbon dioxide rebreathing during eye surgery under retrobulbar anaesthesia.

BACKGROUND: Carbon dioxide concentration under ophthalmic drapes increases during eye surgery under local anaesthesia. A new prototype has been designed which combines continuous suction of carbon dioxide enriched air and continuous oxygen insufflation under ophthalmic drapes to prevent carbon dioxide accumulation in spontaneously breathing patients undergoing cataract surgery. METHODS: In a prospective randomised single blind study the effectiveness of this new prototype was examined in 50 unpremedicated elderly patients. In 25 patients suction was applied under ophthalmic drapes, whereas in the other 25 patients no suction was used. In all cases oxygen was insufflated under the drapes at a constant flow of 2 l/min. Carbon dioxide concentration in the ambient air surrounding the patient's head under ophthalmic drapes, transcutaneous partial pressure of carbon dioxide, respiratory rate, and oxygen saturation were measured. RESULTS: Carbon dioxide concentration under the drapes, transcutaneous partial pressure of carbon dioxide, and respiratory rate remained unchanged in the suction group, whereas in the non-suction group these values increased significantly. Oxygen saturation rose significantly in both groups without differences between the groups. CONCLUSION: Application of this new prototype for continuous aspiration of carbon dioxide enriched air prevents carbon dioxide rebreathing and subsequent hypercapnia associated with an elevated respiratory rate. This new equipment may therefore be useful in patients undergoing ophthalmic surgery under retrobulbar anaesthesia.

Accumulation of carbon dioxide under ophthalmic drapes during eye surgery: a comparison of three different drapes.

Carbon dioxide accumulation under ophthalmic drapes is caused by their impaired permeability to exhaled carbon dioxide in spontaneously breathing patients. Three different ophthalmic drapes were examined under clinical conditions. Sixty unpremedicated patients of each gender, aged over 60 years and with an ASA status of I-III undergoing cataract surgery under retrobulbar anaesthesia were included in the study. Patients with known pulmonary diseases were excluded. The patients were divided into three groups of 20 patients each. In all groups, oxygen was insufflated under the drapes at a constant flow of 21.min-1. Carbon dioxide concentration in the inspired air, transcutaneous carbon dioxide pressures, respiratory rate and oxygen saturation by pulse oximetry were measured. Accumulation of carbon dioxide under the drapes, increase of partial pressure of transcutaneous carbon dioxide and hyperventilation were observed in all three groups. An oxygen supply of 21.min-1 prevented hypoxaemia but not hypercapnia. Therefore, producers of ophthalmic drapes are encouraged to look for further ways to increase the carbon dioxide permeability of their drapes with the aim of reducing carbon dioxide accumulation and hyperventilation in spontaneously breathing patients undergoing eye surgery.