Switching of ± 360° domain wall states in a nanoring by an azimuthal Oersted field.

We demonstrate magnetic switching between two 360° domain wall vortex states in cobalt nanorings, which are candidate magnetic states for robust and low power magnetoresistive random access memory (MRAM) devices. These 360° domain wall (DW) or 'twisted onion' states can have clockwise or counterclockwise circulation, the two states for data storage. Reliable switching between the states is necessary for any realistic device. We accomplish this switching by applying a circular Oersted field created by passing current through a metal atomic force microscope tip placed at the center of the ring. After initializing in an onion state, we rotate the DWs to one side of the ring by passing a current through the center, and can switch between the two twisted states by reversing the current, causing the DWs to split and meet again on the opposite side of the ring. A larger current will annihilate the DWs and create a perfect vortex state in the rings.

High contrast, depth-resolved thermoreflectance imaging using a Nipkow disk confocal microscope.

We have developed a depth-resolved confocal thermal imaging technique that is capable of measuring the temperature distribution of an encapsulated or semi-obstructed device. The technique employs lock-in charge coupled device-based thermoreflectance imaging via a Nipkow disk confocal microscope, which is used to eliminate extraneous reflections from above or below the imaging plane. We use the confocal microscope to predict the decrease in contrast and dynamic range due to an obstruction for widefield thermoreflectance, and we demonstrate the ability of confocal thermoreflectance to maintain a high contrast and thermal sensitivity in the presence of large reflecting obstructions in the optical path.

Use of hecate-chorionic gonadotropin beta conjugate in therapy of lutenizing hormone receptor expressing gonadal somatic cell tumors.

Improvement of cancer treatment is a major challenge of medical research. Despite the immense efforts made in the improvement of diagnosis and treatment, cancer remains a major concern and cause of morbidity and mortality. Most of the modern anti-neoplastic therapies have severe side effects, and tumor cells often develop drug resistance. There is promise in the new generation of treatments (gene therapy, immunotherapy, vaccines, etc.) that are under development, but the efficacies and side effects of such therapies have so far been disappointing. Receptor-based therapies are not new, but many normal cells also present the same receptors reducing the specificity of such approaches. Several lytic peptides have been investigated because of they appear to kill cancer cells due to changes of their membrane potential. Thus, linking receptor-specific ligands to lytic peptides is expected to augment the specificity of targeting and decrease the toxicity of lytic peptides on normal cells. One such polypeptide is hecate (an analogue to the bee venom main component, melittin) that preferentially kills cancer cells at low doses. When this peptide is fused with the 81-95 amino acid fragment of chorionic gonadotropin-beta (CGbeta) subunit (hecate-CGbeta), it targets cells expressing luteinizing hormone receptor (LHR), even at very low doses, or when LHR is expressed at low level. Our recent data showed that this peptide conjugate is efficient in destroying LHR-positive cells in xenografts and more importantly in transgenic mouse models developing LHR-positive somatic cell tumors in gonads. The mechanism of action of hecate-CGbeta after binding to LHR is destruction of cell membranes resulting in rapid cell death by necrosis with minimal side effects. This review summarizes our findings on the action of this novel peptide and considers the future potential of this family of targeting peptides in the treatment of neoplasias.

Ultrahigh-density nanowire arrays grown in self-assembled diblock copolymer templates.

We show a simple, robust, chemical route to the fabrication of ultrahigh-density arrays of nanopores with high aspect ratios using the equilibrium self-assembled morphology of asymmetric diblock copolymers. The dimensions and lateral density of the array are determined by segmental interactions and the copolymer molecular weight. Through direct current electrodeposition, we fabricated vertical arrays of nanowires with densities in excess of 1.9 x 10(11) wires per square centimeter. We found markedly enhanced coercivities with ferromagnetic cobalt nanowires that point toward a route to ultrahigh-density storage media. The copolymer approach described is practical, parallel, compatible with current lithographic processes, and amenable to multilayered device fabrication.

Changes in heart rate variability in elderly patients undergoing major noncardiac surgery under spinal or general anesthesia.

BACKGROUND AND OBJECTIVES: Heart rate variability (HRV), widely used as an indicator of activity of the autonomic nervous system, has been reported to decrease during and after both spinal and general anesthesia in patients without cardiovascular disease. We evaluated the changes in HRV bands in 40 patients with a high risk of ischemic heart disease. METHODS: The patients were randomly assigned to receive either spinal (SA) or general anesthesia (GA) for elective total hip arthroplasty or peripheral vascular surgery. Anesthetic techniques and perioperative fluid administration were standardized. Holter monitoring was started preoperatively and continued until the third postoperative day. Three HRV frequency bands were analyzed. RESULTS: A significant decrease was seen in very low frequency (VLF) and low frequency (LF) bands during GA but not during SA. Also the LF/high frequency (HF) ratio decreased during GA but not during SA. A decrease in all HRV frequency bands was seen after both types of anesthesia. None of the frequency bands returned back to the preoperative level during the 3-day trial. Postoperatively circadian variation was found only in the VLF band after SA. CONCLUSIONS: The sympathovagal balance (LF/HF) is more stable during SA than during GA in patients with a high risk of ischemic heart disease. The postoperative decrease in HRV bands, however, is independent of the anesthetic technique.

Factors associated with post-operative myocardial ischaemia in elderly patients undergoing major non-cardiac surgery.

Forty patients (> 65 years) undergoing hip arthroplasty or peripheral vascular surgery both associated with high risk for post-operative myocardial ischaemia were randomized to receive either spinal or general anaesthesia. Ambulatory ECG recording (Holter) until the third post-operative morning, a daily 12-lead ECG and serum creatine kinase and troponine concentraItions were obtained. The number of ischaemic episodes, total duration of ischaemia and ischaemic minutes per hour were noted for each patient peri-operatively. Sixteen of the patients (40%) had post-operative myocardial ischaemia. An intra-operative increase in the plasma concentration of norepinephrine but not epinephrine was detected in the patients who later developed post-operative myocardial ischaemia. The increase in plasma norepinIephrine concentrations correlated with the decrease in core temperature. The type of anaesthesia had no effect on the incidence of myocardial ischaemia during or after surgery. Our results suggests that intra-operatively decreased core temperature and the increase in plasma concentration of norepinephrine probably caused peripheral vasoconstriction leading to latent cardiac dysfunction. These events should be avoided in the patients at risk of post-operative cardiac ischaemia.

Efficacy and side effects of tramadol versus oxycodone for patient-controlled analgesia after maxillofacial surgery.

Tramadol, a weak opioid mu-receptor agonist, may have a favourable potency and side effect profile for intravenous patient-controlled analgesia (PCA). In a prospective, double-blind, randomized study involving 54 patients, tramadol was compared with oxycodone in PCA after maxillofacial surgery. All the patients were given diclofenac sodium 1 mg kg-1 intramuscularly and dexamethasone 8 mg twice a day. Post-operatively patients received tramadol or oxycodone by a PCA apparatus (lockout 5 min, tramadol 0.3 mg kg-1 bolus, oxycodone 0.03 mg kg-1 bolus). During the immediate recovery period, opioid was administered i.v. in a double-blind fashion, either tramadol 10 mg or oxycodone 1 mg increments until the pain control was judged to be satisfactory by the patient. Pain was assessed at rest and during activity (mouth opening) before and after loading, at 2 h after commencing the PCA, as well as at 21.00 and at 09.00 hours on the following morning. Side effects were recorded. The potency ratio of tramadol to oxycodone was found to be approximately 8:1. There was no significant difference between the groups in the VAS scores for pain. No respiratory depression was identified. Tramadol was found to provide adequate analgesia after maxillofacial surgery without risk of respiratory depression. However, the incidence of nausea was slightly greater in the tramadol group than in the oxycodone group (44% vs. 28%, NS).

Satisfaction with dental care among elderly Finnish men.

To study satisfaction with dental care among elderly Finnish men and to estimate the role of different factors affecting it, a questionnaire was sent to a systematic sample of 2043 elderly Finnish men (mean age 73 years). Acceptably filled-out questionnaires were returned by 1561, a participation rate of 76.4%. The questionnaire included 44 questions concerning dental and denture services and a modified 14-item Dental Satisfaction Questionnaire. The subjects were asked to express how strongly they agreed or disagreed with each of the 14 statements. These were later transformed and recoded to indicate level of satisfaction from +2 (very satisfied) to -2 (very dissatisfied). Overall satisfaction was estimated by summing up all the 14 scores. Dentate subjects were significantly (P<0.01) more satisfied than the edentulous. Subjects were least satisfied with dental care fees and most satisfied with accessibility and availability of services. Dentate subjects viewed almost all 14 items significantly more favorably than did the edentulous. Economics was seen to have a strong influence on dissatisfaction with dental care fees, which was related to income level. Maintaining the remaining dentition and supporting the dentition with fixed or removable dentures seem to be the means to increase satisfaction among the dentate. The benefits of belonging to a clinic's recall system should be explained thoroughly to the elderly.

Comparison of double-hole and single-hole pencil-point needles for spinal anesthesia with hyperbaric bupivacaine.

BACKGROUND AND OBJECTIVES: The use of thin single-hole pencil-point (SHPP) spinal needles may be a reason for subarachnoid maldistribution of local anesthetic. A new double-hole pencil-point (DHPP) needle may be preferable because of a theoretic more uniform initial distribution of local anesthetic. METHODS: This was a prospective, double-blinded study of 50 patients randomly selected to have spinal anesthesia using either single-hole 27-gauge (B. Braun, Melsungen, Germany) or double-hole 26-gauge (A.L.B. Medical Inc., U.S.A.) pencil-point needles. The former were inserted with the side port directed caudally and the latter with openings in both caudal and cranial direction. Two milliliters of hyperbaric 0.5% bupivacaine were injected in 1 minute, and sensory and motor block were studied at regular intervals during spinal anesthesia. All patients were interviewed on the first (personal) and the seventh (mailed questionnaire) postoperative day. Furthermore, microscopic inspection of the spinal needles was performed. RESULTS: There were no statistically significant differences in sensory or motor block levels between the two needle types at any time during spinal anesthesia. Likewise, there was no difference in the duration of spinal block. The postanesthetic side effects (headache, backache, pricking, numbness, weakness) were similar in both groups. Light and electron microscopic examination showed resistance of the SHPP needles to tip damage. On the other hand, the DHPP needle tips seemed to be distorted quite frequently, and, even in unused needles, the tip was blunt and asymmetric. CONCLUSION: There was no difference between the spread of analgesia using either SHPP or DHPP spinal needles. The DHPP needles appear to be vulnerable to tip damage from mechanical contact.

Comparison of intrathecal morphine and continuous femoral 3-in-1 block for pain after major knee surgery under spinal anaesthesia.

Major knee surgery is associated with moderate or severe post-operative pain. Intrathecal morphine and continuous femoral 3-in-1 block were compared prospectively in 40 patients for pain after major knee surgery under spinal anaesthesia, with 4 mL isobaric 0.5% bupivacaine. In a random order, 20 patients received preservative free morphine 0.3 mg mixed with spinal bupivacaine. In 20 patients, following spinal anaesthesia with only bupivacaine, femoral 3-in-1 block was performed post-operatively with 0.5% bupivacaine 2 mg kg-1. The block was continued via a catheter with 0.25% bupivacaine 0.1 mL h-1 kg-1 until the next morning (24 h after induction of spinal anaesthesia). Intramuscular oxycodone was given as a rescue analgesic in all patients. Two patients from the femoral group were excluded due to technical failure. Three patients in the morphine group and one patient in the femoral group did not need any additional oxycodone. In the morphine group on average 2.8 (range 0-7) and in the femoral group 3.2 (0-5) additional doses of oxycodone were needed during the 24 h observation period. The mean pain scores were significantly lower in the morphine group at 9 and 12 h into the 24-h trial. Itching was seen only in the morphine group (40% of the patients). Other side effects were similar in the two groups. All patients were satisfied with their pain therapy. Both intrathecal morphine and femoral 3-in-1 block alone were insufficient for the treatment of severe pain after major knee surgery.

Comparison of respiratory effects of tramadol and pethidine.

Tramadol is a centrally acting opioid with a low affinity for mu-opioid receptors, which has been claimed not to depress respiration as do the classic opioids. The respiratory effects of intravenous (i.v.) pethidine (0.6 mg kg-1) and tramadol (0.6 mg kg-1) were compared in 36 ASA Grade I-II patients in a placebo-controlled double-blind study. After induction of anaesthesia with propofol followed by suxamethonium-facilitated endotracheal intubation, the patients spontaneously breathed halothane in 70% nitrous oxide and oxygen via a non-rebreathing valve. Inspiratory and expiratory oxygen, and end-tidal carbon dioxide concentrations (PETCO2), tidal volume (VT), minute volume of ventilation (MV) and respiratory rate were monitored by a side-stream spirometry at an end-tidal halothane of 0.3%. The recordings were collected before surgery. Pethidine caused significant respiratory depression seen as an increase in fractional inspiratory-expiratory oxygen difference and PETCO2 and as a decrease in MV and respiratory rate. However, the effects of tramadol were similar to those of a placebo. Tidal volume was not affected by any study drug. In conclusion, tramadol 0.6 mg kg-1 was shown not to be associated with respiratory depression, unlike equipotent dose of pethidine in this setting.

Comparison of respiratory effects of tramadol and oxycodone.

STUDY OBJECTIVE: To compare the respiratory effects of tramadol and oxycodone. DESIGN: Placebo-controlled, double-blind randomized study. SETTING: IV Department of Surgery, Helsinki University Central Hospital. PATIENTS: 36 ASA physical status I and II patients undergoing minor surgery with general anesthesia. INTERVENTIONS: The respiratory effects of intravenous (i.v.) tramadol 0.6 mg/kg and oxycodone 0.04 mg/kg were compared after induction of anesthesia with propofol and succinylcholine-facilitated endotracheal intubation. Patients spontaneously breathed halothane in 70% nitrous oxide and oxygen via a nonrebreathing valve. The trial drugs or placebo were given after recovery from neuromuscular block. MEASUREMENTS AND MAIN RESULTS: Inspiratory and expiratory oxygen and end-tidal carbon dioxide concentrations (ETCO2), tidal volume (VT) minute volume of ventilation (VE), and respiratory rate (RR) were recorded by side-stream spirometry with end-tidal halothane of 0.3% for 30 minutes before surgery. Oxycodone caused a significant respiratory depression seen as an increase in the inspiratory-expiratory oxygen difference and ETCO2 and as a decrease in VE and RR. On the contrary, the effect of tramadol were similar to those of placebo. VT was not affected by any study drug. CONCLUSION: Tramadol was not associated with respiratory depression in the present setting.

Comparison of metoclopramide and ondansetron for the prevention of nausea and vomiting after intrathecal morphine.

Nausea and vomiting remain unpleasant side effects of intrathecal (i.t.) morphine and of the numerous therapies tried, only prophylactic intravenous (i.v.) metoclopramide has been reported to be promising. Seventy-three patients, scheduled for orthopaedic prosthesis surgery of the hip or knee were studied. They received 4 mL of plain bupivacaine and 0.3 mg of preservative-free morphine i.t. for anaesthesia. The test drugs given in a double-blind and randomized fashion, were either metoclopramide 20 mg, three times, at 6 h intervals (23 patients), ondansetron, 8 mg, twice, at 12 h intervals (25 patients), or 0.9% saline three times, at 6 h intervals (25 patients). The occurrence of nausea, vomiting and pain was followed for 24 h. The incidences of nausea and vomiting were 60% (15/25) and 56% (14/25) in the saline group, 52% (12/23) and 48% (11/23) in the metoclopramide group, and 52% (13/25) and 40% (10/25) in the ondansetron group. Incidences of severe vomiting were 24, 35 and 12% respectively. Eight patients in the saline group, seven in the metoclopramide and 10 in the ondansetron group did not need additional opioids for post-operative pain relief. We conclude that, metoclopramide and ondansetron were not better than saline in the prevention of post-operative emesis induced by intrathecal morphine.

Home-readiness after spinal anaesthesia with small doses of hyperbaric 0.5% bupivacaine.

Fifty-four patients were studied prospectively to evaluate home-readiness after a small dose (1 or 2 ml) of subarachnoid hyperbaric 0.5% bupivacaine. The block regressed significantly earlier in the 1 ml group than in the 2 ml group (p < 0.05). The patients were also able to walk significantly earlier in the 1 ml group (median 161 min and 231 min in the 1 ml and 2 ml groups, respectively) (p < 0.05). However, there were no significant differences between the groups in time of ability to void. We conclude that adequate surgical anaesthesia can be achieved with small doses of hyperbaric bupivacaine used for spinal anaesthesia. Although the sensory and motor block after 1 or 2 ml hyperbaric bupivacaine recovered within a reasonable time for day-case surgery, in some patients recovery of the ability to void was delayed to an undesirable extent.

Intravenous ketorolac vs diclofenac for analgesia after maxillofacial surgery.

PURPOSE: To compare the efficacy of the non-steroidal antiinflammatory drugs (NSAID), ketorolac and diclofenac in prevention of pain after maxillofacial surgery. METHODS: Sixty ASA I-II patients (30 in each group) received randomly, and double blindly either ketorolac 0.4 mg.kg-1 or diclofenac 1.0 mg.kg-1 iv after general anaesthesia induction, before surgical incision. In the ketorolac group, the same dose was repeated iv three times at six hour intervals. The diclofenac group patients received diclofenac 1.0 mg.kg-1 after 12 hr iv. Rescue analgesic medication consisting of oxycodone 0.03 mg.kg-1 iv, was administered by a patient controlled analgesia apparatus. RESULTS: Two patients in the ketorolac and three patients in the diclofenac group did not need oxycodone during the study period. On average, 12 and 11 doses of oxycodone were needed in the ketorolac and the diclofenac groups, respectively (NS). Side-effects were similar in both groups. All patients except one were satisfied with the pain therapy. CONCLUSION: Parenteral ketorolac (0.4 mg.kg-1 four times in 24 hr) and diclofenac (1 mg.kg-1 twice in 24 hr) were similar, but insufficient alone, for analgesia after maxillofacial surgery.

Growth and type-II collagen expression in the glenoid fossa of the temporomandibular joint during altered loading: a study in the rat.

The aim of this study was to measure changes in growth of the glenoid fossa and its articular eminence after decreased loading. A further aim was to evaluate the role of mechanical forces in relation to the existence of a cartilage layer, by determining type-II collagen secretion. A total of 99 Wistar rats were used: 48 animals were fed whole pellets and 51 were fed ground pellets. At age 21 days, after weaning, the upper and lower incisors of the soft-diet group were shortened by cutting them, twice a week. Ten animals fed whole pellets and 10 fed ground pellets were injected i. p. with Alizarin red (200 mg/kg) at ages 22, 30 and 40 days, and killed at ages 30, 40 and 50 days respectively. The heads were freed from the soft tissue and the zygomatic process cut sagittally at the deepest point of the greatest transversal concavity of the eminence. Bone apposition was measured. The other animals were used for studies involving collagen II immunostaining. Bone growth decreased in the group fed ground pellets except in the anterior-most part of the glenoid fossa at 50 days. Immunohistochemical analysis revealed larger areas of anti-collagen II staining in the group fed whole pellets, most markedly in the posterior part of the glenoid fossa. Growth of the articulationg surface of the temporal component of the temporomandibular joint appears to depend on mechanical factors, such as the condyle. The underlying mechanics seem likely to be different. The presence of type-II collagen is obviously not regulated only by compressive forces but probably also by tension loading.

Transient radicular irritation after bupivacaine spinal anesthesia.

BACKGROUND AND OBJECTIVES: Transient radicular irritation (TRI) has been described to occur following spinal anesthesia with hyperbaric 5% lidocaine. The authors recently used only isobaric or hyperbaric 0.5% bupivacaine for spinal anesthesia. All patients who had spinal anesthesia for various kinds of surgery were interviewed after the operation to discover the possibility of TRI following bupivacaine spinal anesthesia. METHODS: The study included 226 patients. Isobaric 0.5% bupivacaine was given to 116 patients and hyperbaric 0.5% bupivacaine to 110. The local anesthetic was chosen according to the expected duration of surgery. All patients were interviewed by an anesthesiologist 24 hours after spinal anesthesia, and after 1 week the patients were asked to return a written questionnaire. If pain not associated with operation was noted, the patients were interviewed by phone. RESULTS: One 48-year-old woman reported TRI after spinal anesthesia (saddle block) with hyperbaric 0.5% bupivacaine in the 24-hour interview. Her spinal anesthetic was performed in a sitting position and the anal surgery in a lithotomy position. In the 1-week questionnaire (response rate 92%), none of the other patients fulfilled our criteria for TRI. CONCLUSIONS: In spite of one case of TRI, the authors consider bupivacaine to be safe for spinal anesthesia. The association of the sitting and lithotomy positions to the restricted distribution of hyperbaric solution and consequent TRI warrants further studies.

Effect of reduced articular function on deposition of type I and type II collagens in the mandibular condylar cartilage of the rat.

A group of rats was fed a soft diet after weaning and the incisors shortened regularly to keep them out of occlusion. The controls were fed a hard diet. Immunohistochemical techniques and image analysis were employed to investigate deposition of pro-type I collagen and type II collagen, and the thickness of articular cartilage layers in the mandibular condyle. The immunostaining against pro-type I collagen was most intense intracellularly in the fibrous and upper chondroblast layers in 30- and 50-day-old rats fed a hard diet. In the rats fed a soft diet, marked intra- and extracellular staining against pro-type I collagen was visible in the upper chondroblast and upper hypertrophic layers but also in the lower hypertrophic layer. The intensity of staining against type II collagen was weak in animals on a soft diet, while in the animals fed a hard diet the staining was intense in the superior layers of mature chondroblasts. The total number of chondroblasts recorded was reduced by 35 percent at the age of 50 days in the soft-diet compared to the hard-diet animals. The results show that the deposition of type I and II collagens, the thickness of the cartilage cell layers and the number of chondrocytes are sensitive to alterations in loading.

Premedication with promethazine and transdermal scopolamine reduces the incidence of nausea and vomiting after intrathecal morphine.

Intrathecal morphine provides effective postoperative pain relief in major orthopaedic surgery. In use, however, is associated with unpleasant side effects like nausea and vomiting. The effect of different premedications on postoperative emetic sequelae induced by intrathecal morphine was studied in a prospective, double blind study. Sixty patients scheduled for arthroplasty surgery of the lower extremity were anaesthetized with spinal anaesthesia with a combination of isobaric bupivacaine 20 mg and morphine 0.3 mg. For premedication the patients were randomised to three groups of equal size. They received either oral diazepam (5-15 mg), oral promethazine (10 mg) or a combination of promethazine and transdermal scopolamine (1.5 mg). Sixty percent of the patients with both promethazine and transdermal scopolamine were totally free from postoperative nausea and vomiting (PONV) symptoms compared to those premedicated with diazepam (40%) or promethazine alone (30%). Promethazine together with transdermal scopolamine reduced significantly the number of patients with vomiting (to 25%) and also vomiting episodes. This combination was also more efficient in reducing the incidence of nausea (to 25%) and nausea episodes than promethazine along (P < 0.05). Combination also reduced the requests for additional pain relief (P < 0.05). PONV occurred in a majority of patients during the first 12 hours of the 24 hour study period and the need for additional analgesics thereafter. The incidence of itching (50-65%) and urinary catheterisation (55-70%) was similar in all groups. In conclusion, the combination of oral promethazine and transdermal scopolamine was most effective in reducing PONV symptoms and also reduced the need for postoperative pain treatment.