Decoherence of an n-qubit quantum memory

We analyze decoherence of a quantum register in the absence of nonlocal operations, i.e., n noninteracting qubits coupled to an environment. The problem is solved in terms of a sum rule which implies linear scaling in the number of qubits. Each term involves a single qubit and its entanglement with the remaining ones. Two conditions are essential: first, decoherence must be small, and second, the coupling of different qubits must be uncorrelated in the interaction picture. We apply the result to a random matrix model, and illustrate its reach considering a Greenberger-Horne-Zeilinger state coupled to a spin bath.

Universal and nonuniversal level statistics in a chaotic quantum spin chain

We study the level statistics of an interacting multiqubit system, namely the kicked Ising spin chain, in the regime of quantum chaos. Long range quasienergy level statistics show effects analogous to the ones observed in semiclassical systems due to the presence of short classical periodic orbits, while short range level statistics display perfect statistical agreement with random matrix theory. Even though our system possesses no classical limit, our results suggest existence of an important nonuniversal system specific behavior at short time scale, which clearly goes beyond finite size effects in random matrix theory.

Imaging studies in the diagnosis and management of vasculitis

The term vasculitis encompasses a number of distinct clinicopathologic disease entities. Final diagnosis should be supported by histologic study in most cases. However, different imaging modalities offer the potential for an early visualization of inflammatory vascular abnormalities, provide some diagnostic clues, and allow for an adequate assessment of therapeutic response. This review discusses recent advances in imaging techniques and refinements in vascular imaging methods, as well as a brief mention of research modalities that are increasingly used in studies of pathogenesis or in the assessment of disease progression.

The OMERACT Ultrasound Group: status of current activities and research directions

Ultrasound (US) is a relatively new imaging modality in rheumatology that offers great potential as a diagnostic and management tool. In 2004, an OMERACT Ultrasound Special Interest Group was formed to address the metric qualities of US as a potential outcome measure. A preliminary systematic review highlighted the deficiencies in the literature, particularly with regard to the reliability of interpreting and acquiring images; as a consequence, a number of exercises were proposed to address these issues. This report describes a series of iterative studies that have resulted in improved intra- and inter-reader reliability for detecting and scoring synovitis from both static and real-time images of the hand joints of patients with rheumatoid arthritis. The reliability of acquiring images was also enhanced using standardized positions. Future studies will assess the value of US in clinical trials.

Imaging of osteomyelitis: current concepts

Osteomyelitis frequently requires more than one imaging technique for an accurate diagnosis. Conventional radiography still remains the first imaging modality. MRI and nuclear medicine are the most sensitive and specific methods for the detection of osteomyelitis. MRI provides more accurate information regarding the extent of the infectious process. Ultrasound represents a noninvasive method to evaluate the involved soft tissues and cortical bone and may provide guidance for diagnostic or therapeutic aspiration, drainage, or tissue biopsy. CT scan can be a useful method to detect early osseous erosion and to document the presence of sequestra. PET and SPECT are highly accurate techniques for the evaluation of chronic osteomyelitis, allowing differentiation from soft tissue infection.

Kidney involvement in Takayasu arteritis

OBJECTIVE

To evaluate whether the presence of glomerulonephritis is or is not associated with the extent of arterial wall inflammatory cell infiltrate in Takayasu arthritis (TA).

METHODS

Retrospective chart and pathology review of large artery and kidney specimens of TA autopsy cases. Kidney specimens were classified, according to their histopathological findings, in those with specific glomerular entities and those with non-specific, ischemic and/or hypertensive, glomerular changes. A control group of autopsy kidney specimens was utilized for comparison. Morphometric analysis was used to assess the extent of the arterial inflammatory infiltrates; results were compared among the different groups with kidney lesions.

RESULTS

We included 25 kidney specimens from 25 autopsies. Specific glomerular entities were present in 14 specimens; 10 (40%) were classified as diffuse mesangial proliferative glomerulonephritis (DMPG [Group A]), and 4 (16%) as other associated glomerulopathies (Group B). Non-specific changes were observed in 11 (44%) specimens (Group C). The arterial inflammatory infiltrate proportion was 9.4 % for group A, 1.4% for group B, and 2.7% for group C. Furthermore, a larger proportion of vascular inflammation was confirmed for group A when compared with the other groups (p<0.05). Group A patients were younger than those in groups B and C (p<0.005) and exhibited shorter disease duration.

CONCLUSION

The presence of DMPG was associated with a larger extent of vascular inflammatory cell infiltrate, suggesting a relationship between both phenomena.

Sphygmomanometry-Evoked Allodynia???A Simple Bedside Test Indicative of Fibromyalgia

BACKGROUND

One of the 2 classification criteria for fibromyalgia (FM) is the presence of tender points on specific anatomic sites. It has been established that these tender points reflect a state of generalized allodynia (defined as pain resulting from a stimulus that does not normally provoke pain). Patients with FM often describe pain elicitation during blood pressure testing (sphygmomanometry).

OBJECTIVE

The objective of this study was to define if a universally used clinical test, sphygmomanometry, is helpful in the identification of patients with FM.

METHODS

The authors conducted a prospective multicenter study in 3 different public rheumatology outpatient services. Each center studied 20 patients with FM, 20 with rheumatoid arthritis, 20 with osteoarthritis, and 20 healthy individuals. The following question was asked of each participant: "When I take your blood pressure, tell me if the cuff's pressure brings forth pain." The blood pressure cuff was inflated at an approximate rate of 10 mm Hg per second up to 180 mm Hg or to the point when pain was elicited.

RESULTS

Sixty-nine percent of patients with FM had sphygmomanometry-evoked allodynia in contrast to 10% of patients with osteoarthritis, 5% with rheumatoid arthritis, and 2% of healthy individuals (P < 0.001). The mean blood pressure value at which allodynia was elicited was lower in patients with FM (143 +/- 40 mm Hg) when compared with the other 3 groups (176 +/- 11 mm Hg) or higher (P < 0.001). In patients with FM, there was a significant negative correlation between the blood pressure value at which allodynia developed and total Fibromyalgia Impact Questionnaire (FIQ) score, number of tender points, and the FIQ visual analog scales for pain intensity and fatigue (P < 0.05). The test yields a diagnostic sensitivity for FM of 0.7, specificity 0.96, positive predictive value 0.86, and negative predictive value 0.91.

CONCLUSIONS

In this developmental study of patients attending rheumatology clinics, the generation of pain during blood pressure testing was strongly associated with the diagnosis of FM. This robust linkage probably reflects a tautologic phenomenon. A sine qua nonelement for FM diagnosis is the presence of tender points in discrete anatomic sites. These tender points in turn reflect a state of generalized mechanical allodynia that can be locally elicited by the cuff pressure during blood pressure testing. Sphygmomanometry is a simple bedside test that may be useful in the recognition of patients with FM. Blood pressure testing is a universal procedure in all clinical environments. Based on our results, we suggest searching for FM features in any person who has sphygmomanometry-evoked allodynia.

Microscopic polyangiitis associated with primary biliary cirrhosis: a causal or casual association?

The association between microscopic polyangiitis (MPA) and primary biliary cirrhosis (PBC) has seldom been reported. We describe a patient with PBC and MPA who presented with polyarthritis and pulmonary nodules followed by pauci-immune crescentic glomerulonephritis and liver dysfunction. Detection of p-ANCA, antimyeloperoxidase, and antimitochondrial antibodies along with liver and renal histopathology allowed a diagnosis of MPA and PBC. We also discuss 2 other cases that could be unrecognized associations of both diseases. Further reports are necessary to clarify if the coexistence between PBC and MPA is causal or casual.

Verification of generic fidelity recovery in a dynamical system

We study the time evolution of fidelity in a dynamical many-body system, namely, a kicked Ising model, modified to allow for a time-reversal invariance breaking. We find good agreement with the random matrix predictions in the realm of strong perturbations. In particular for the time-reversal symmetry breaking case the predicted revival at the Heisenberg time is clearly seen.

Concurrent cisplatin/gemcitabine chemotherapy along with radiotherapy in locally advanced cervical carcinoma: A phase II trial

OBJECTIVE

To evaluate the efficacy and safety of a concurrent regimen of gemcitabine/cisplatin and radiotherapy in women with locally advanced cervical carcinoma (LACC).

METHODS

From April 2001 to June 2002, we enrolled women diagnosed with histologically proven LACC (FIGO stages IIA through IIIB), for treatment with concurrent regimen of chemo-radiotherapy. The treatment consisted of: cisplatin 40 mg/m(2), followed by gemcitabine 125 mg/m(2), once weekly, given about 1 to 2 h before radiotherapy. External beam radiation was delivered 5 days/week to entire pelvic radiation field for a total of 50 Gy in 25 fractions over 5 weeks. After completion of external radiation, patients received brachytherapy with cesium-137 via standard Fletcher-suit applicators delivering 30 Gy to point A.

RESULTS

Of the 23 enrolled patients (mean age 47 years), 20 completed the treatment and were evaluable for response and safety. The complete response rate was 90% (18/20), and partial response rate was 10% (2 patients with persistent disease after therapy). Toxicity was moderate: 2 patients required blood transfusions; 5% patients had grade 2 leukopenia or thrombocytopenia; 40% had grade 1-2 nausea-vomiting, and 50% had grade 1 diarrhea. At a median follow-up of 12 months, all patients are alive, and 16/20 (80%) are disease-free.

CONCLUSIONS

The gemcitabine/cisplatin combination administered concurrently with radiotherapy is highly active in locally advanced cervical carcinoma. The tolerable toxicity and synergistic activity of this concurrent chemoradiation regimen are consistent with prior reports. Definitive results are awaited from an on-going large, randomized trial comparing this regimen with standard treatment.

Musician's Cramp

Musician's focal dystonia is a motor dysfunction that appears in artists after years of repetitive and fine movements during performance. This is the condition most feared by musicians because it leads to difficulties in controlling movements, which can interrupt or terminate their careers. It is characterized by the onset of involuntary muscle contractions and movements; its distinguishing feature is that it only occurs during a specific and well-defined action. It is rarely diagnosed because those who experience it do not seek medical attention for fear or shame, but also because many physicians do not consider the disease in the differential diagnosis of motor dysfunction. We describe the case of a guitarist who presented to our outpatient clinic after many years of experiencing musician's focal dystonia. He reported a long list of misdiagnoses and a variety of unsuccessful treatments.Musician's focal dystonia is an under-diagnosed condition. Treatment benefit is limited despite recent innovative approaches. Rheumatologist should be aware of this condition.

Osteopoikilosis in an ancient skeleton: more than a medical curiosity

We describe the palaeopathologic and radiographic findings of the human skeletal remains that belonged to a female who lived in Mexico's viceroyship period (seventeenth and eighteenth centuries A.D.). Radiographic studies showed numerous, radiodense, ovoid, small and well-defined foci in the long tubular bones, sacrum, scapulae and iliac bones. Computed tomography (CT) examination revealed multiple hyperdense foci located in the central marrow portion of the bones. Measurements of attenuation coefficient revealed +1548 HU. The findings are consistent with osteopoikilosis, an uncommon, benign sclerosing bone dysplasia transmitted in an autosomal dominant fashion, which in the clinical setting is important to set apart from different bone pathologies to avoid unnecessary interventions and treatments. To the best of our knowledge, this is the first report of osteopoikilosis in ancient human remains.

Intracranial aneurysms associated with unsuspected aortic coarctation

Intracranial aneurysms (IAs) are found more often in patients with aortic coarctation (AC) than in the general population and aneurysm rupture occurs much earlier in the lives of these patients when there is coexistent AC. The diagnosis of AC is frequently made only after a serious cerebrovascular complication has developed. The aim of this paper is to call attention to AC in patients presenting with aneurysmal subarachnoid hemorrhage. The literature is reviewed, the key clinical features are highlighted, and the proposed pathogenesis of this association is discussed. The authors present clinical information and imaging data obtained in three young patients with ruptured IAs that were associated with initially unnoticed AC. Abnormal results of cardiovascular examinations led the authors to consider an underlying AC, which was later confirmed by aortography. These aneurysms were successfully treated prior to correction of the ACs. The diagnosis of AC should be considered in adolescent and young adult patients presenting with IAs.

Development of a radiographic index to assess the tarsal involvement in patients with spondyloarthropathies

OBJECTIVE

To develop and test an index to evaluate the radiographic changes that occur in the tarsus and adjacent areas of the foot in patients with spondyloarthropathies (SpA).

METHODS

The spondyloarthropathy tarsal radiographic index (SpA-TRI) was developed in three consecutive steps: (a) detection of descriptors after reviewing 70 radiographic files; (b) descriptor gradation and subsequent modifications performed by a consensus committee, and (c) interobserver variability assessed by three blinded and independent observers on 272 radiographs: anteroposterior 118, lateral 90, oblique 64 from 121 patients with SpA, and intraobserver variability on 75 radiographs from 25 patients with SpA. Statistical analysis included percentage of agreement and kappa test. SpA-TRI score ranges from 0 to 4 (0=normal; 1=osteopenia or suspicious findings; 2=definite joint space narrowing, bony erosion(s), periosteal whiskering, or enthesophyte(s) in the plantar fascia or Achilleal tendon attachments; 3=para-articular enthesophyte(s); 4=bony ankylosis (joint space fusion or complete bridging)).

RESULTS

Complete agreement for every evaluation was >40%, and discordance >1 grade was <15%. The kappa scores among the three observers were acceptable for all the single projections: oblique (0.52, 0.36, 0.35), lateral (0.50, 0.42, 0.56), and anteroposterior (0.40, 0.41, 0.21) views. The combination of lateral and oblique views achieved the highest concordance rates (0.72, 0.33, 0.66), surpassing that of the three projections altogether (0.34, 0.58, 0.37). In every case the concordance was comparable with that of sacroiliac joints (0.47, 0.41, 0.34); intraobserver concordance showed a similar trend.

CONCLUSION

The SpA-TRI is an index that includes the most prominent features of tarsal disease and adjacent areas of the foot in SpA and grades them accordingly, it has an adequate reproducibility, and is suitable for use with two or more projections, preferably the combination of oblique and lateral.

Norepinephrine-evoked pain in fibromyalgia. A randomized pilot study [ISRCTN70707830]

BACKGROUND

Fibromyalgia syndrome displays sympathetically maintained pain features such as frequent post-traumatic onset and stimuli-independent pain accompanied by allodynia and paresthesias. Heart rate variability studies showed that fibromyalgia patients have changes consistent with ongoing sympathetic hyperactivity. Norepinephrine-evoked pain test is used to assess sympathetically maintained pain syndromes. Our objective was to define if fibromyalgia patients have norepinephrine-evoked pain.

METHODS

Prospective double blind controlled study.

PARTICIPANTS

Twenty FM patients, and two age/sex matched control groups; 20 rheumatoid arthritis patients and 20 healthy controls. Ten micrograms of norepinephrine diluted in 0.1 ml of saline solution were injected in a forearm. The contrasting substance, 0.1 ml of saline solution alone, was injected in the opposite forearm. Maximum local pain elicited during the 5 minutes post-injection was graded on a visual analog scale (VAS). Norepinephrine-evoked pain was diagnosed when norepinephrine injection induced greater pain than placebo injection. Intensity of norepinephrine-evoked pain was calculated as the difference between norepinephrine minus placebo-induced VAS scores.

RESULTS

Norepinephrine-evoked pain was seen in 80 % of FM patients (95% confidence intervals 56.3 - 94.3%), in 30 % of rheumatoid arthritis patients and in 30 % of healthy controls (95% confidence intervals 11.9 - 54.3) (p < 0.05). Intensity of norepinephrine-evoked pain was greater in FM patients (mean +/- SD 2.5 +/- 2.5) when compared to rheumatoid arthritis patients (0.3 +/- 0.7), and healthy controls (0.3 +/- 0.8) p < 0.0001.

CONCLUSIONS

Fibromyalgia patients have norepinephrine-evoked pain. This finding supports the hypothesis that fibromyalgia may be a sympathetically maintained pain syndrome.

Effect of levosimendan on myocardial contractility, coronary and peripheral blood flow, and arrhythmias during coronary artery ligation and reperfusion in the in vivo pig model

OBJECTIVE

To determine whether levosimendan, a calcium sensitiser that facilitates the activation of the contractile apparatus by calcium, improves myocardial contractile function during severe ischaemia and reperfusion without exacerbating the incidence of arrhythmias.

DESIGN

Pigs were pretreated orally twice daily for 10 days with 0.08 mg/kg levosimendan or placebo. On day 11 the left main coronary artery was ligated for 30 minutes, followed by 30 minutes of reperfusion. A bolus dose of levosimendan, 11.2 microg/kg intravenously, or placebo was given 30 minutes before coronary ligation, followed by a continuous infusion of 0.2 microg/kg/min levosimendan or placebo for the remainder of the experiment.

RESULTS

During the ischaemic period, cardiac output was higher in the levosimendan group than in the placebo group (mean (SD): 2.6 (0.5) v 2.0 (0.2) l/min, p < 0.05) and systemic vascular resistance was lower (2024 (188) v 2669 (424) dyne.s(-1).cm(-5), p < 0.005). During reperfusion, cardiac output and contractility (LV(max)dP/dt (pos), 956 (118) v 784 (130) mm Hg/s, p < 0.05) were increased by levosimendan. The incidence of ischaemic ventricular fibrillation and tachycardia was similar in the two groups but there were more arrhythmic events (ventricular tachycardia and ventricular fibrillation) in the levosimendan treated group (8/12 levosimendan v 1/9 control p = 0.05).

CONCLUSIONS

Levosimendan improved cardiac output and myocardial contractility during coronary artery ligation and reperfusion. However, it increased the number of arrhythmic events during ischaemia in this model of in vivo regional ischaemia.

Effect of levosimendan on myocardial contractility, coronary and peripheral blood flow, and arrhythmias during coronary artery ligation and reperfusion in the in vivo pig model

OBJECTIVE

To determine whether levosimendan, a calcium sensitiser that facilitates the activation of the contractile apparatus by calcium, improves myocardial contractile function during severe ischaemia and reperfusion without exacerbating the incidence of arrhythmias.

DESIGN

Pigs were pretreated orally twice daily for 10 days with 0.08 mg/kg levosimendan or placebo. On day 11 the left main coronary artery was ligated for 30 minutes, followed by 30 minutes of reperfusion. A bolus dose of levosimendan, 11.2 μg/kg intravenously, or placebo was given 30 minutes before coronary ligation, followed by a continuous infusion of 0.2 μg/kg/min levosimendan or placebo for the remainder of the experiment.

RESULTS

During the ischaemic period, cardiac output was higher in the levosimendan group than in the placebo group (mean (SD): 2.6 (0.5) v 2.0 (0.2) l/min, p < 0.05) and systemic vascular resistance was lower (2024 (188) v 2669 (424) dyne.s−1.cm−5, p < 0.005). During reperfusion, cardiac output and contractility (LVmaxdP/dt (pos), 956 (118) v 784 (130) mm Hg/s, p < 0.05) were increased by levosimendan. The incidence of ischaemic ventricular fibrillation and tachycardia was similar in the two groups but there were more arrhythmic events (ventricular tachycardia and ventricular fibrillation) in the levosimendan treated group (8/12 levosimendan v 1/9 control p = 0.05).

CONCLUSIONS

Levosimendan improved cardiac output and myocardial contractility during coronary artery ligation and reperfusion. However, it increased the number of arrhythmic events during ischaemia in this model of in vivo regional ischaemia.