What is the role of titin in active muscle?

Several properties of muscle defy explanation solely based on the sliding filament-swinging cross-bridge theory. Indeed, muscle behaves as though there is a dynamic "spring" within the sarcomeres. We propose a new "winding filament" mechanism for how titin acts, in conjunction with the cross-bridges, as a force-dependent spring. The addition of titin into active sarcomeres resolves many puzzling muscle characteristics.     

What is the significance of ovarian vein reflux detected by computed tomography in patients with pelvic pain?

Chronic pelvic pain (CPP) is a common gynecological complaint. CPP is nonmenstrual pain localized in the anatomic pelvis of at least 6 months' duration without any identifiable organic cause that is severe enough to cause functional disability and require treatment. Pelvic congestion syndrome (PCS) is a poorly understood disorder and often overlooked cause of pelvic pain. Ovarian vein reflux (OVR) and pelvic varicosities are a cause of PCS. On the other hand, OVR can be seen in asymptomatic women, typically parous. OVR has a characteristic appearance at enhanced computed tomography (CT). Contrast medium retrogradely fills the ovarian veins and parauterine veins during the arterial phase after intravenous contrast administration. CT is not the ideal modality to evaluate all the causes of pelvic pain, but CT is a commonly used diagnostic modality to screen patient who presents with abdominal and pelvic pain. CT can demonstrate abnormal ovarian venous flow as well as tortuous and dilated ovarian and pelvic veins. Ovarian vein reflux is important to recognize and when correlated with patient clinical presentation may help in the diagnosis of PCS.     

What is the definition of a poisoning?

New insights in medicine and acceptable treatments necessitates an adjustment of the existing definition of clinical or forensic poisoning to: 'An individual's medical or social unacceptable condition as a consequence of being under influence of an exogenous substance in a dose too high for the person concerned'. For medical and legal purposes it is important to know how the victim became poisoned. In general, there are three ways of causing medical poisoning: accidental poisoning, including iatrogenic poisoning, experimental and intentional poisoning. Nowadays iatrogenic intoxication, poisoning caused by the Münchhausen's syndrome (by proxy) and experimental poisoning (designer drugs) have a major place in contemporary toxicology. Although some toxicologists use the word 'intoxication' only overdoses with central effects, in this article 'intoxication' and 'poisoning' are considered to be synonymous.     

What is the role of bone scintigraphy in the diagnosis of infected joint prostheses?

AIM: To analyse the role played by bone scintigraphy in the diagnosis of infected joint prostheses. METHODS: The study included 77 patients, aged 32-77 years, in whom infection of a joint prosthesis (48 hip, 29 knee) was suspected. In all patients the following examinations were performed consecutively: a two-phase Tc methylene diphosphonate (Tc-MDP) bone scan, a Tc hexamethylproplyene amine oxime (Tc-HMPAO) labelled white blood cell (WBC) scan, and a Tc microcolloid bone marrow (BM) scan. The minimum interval between examinations was 48 h. The diagnoses were based on data obtained from bacteriological cultures. RESULTS: The bone scan was positive in all patients and 28 of them had an infection (sensitivity 100%, specificity 0%). The WBC scan was positive in 61 patients but only 27 had an infection. The WBC scan was negative in 16 patients, and the possibility of infection was discarded in 15 of these cases (sensitivity 96%, specificity 30%). The results of the bone marrow scan were not compatible with those of the WBC scan (suggestive of infection) in 27 patients: 26 of them had prosthesis infection. The results of both examinations were compatible in the other 34 patients and the possibility of infection was discarded in 33 of these patients (sensitivity 92.8%, specificity 98%). The addition of a BM scan to a WBC scan decreased the sensitivity from 96% to 92.8% but increased specificity from 30% to 98%. The addition of a bone scan to this dual combination did not alter the results. CONCLUSIONS: When infection of a prosthesis is suspected the diagnostic procedure should start with a WBC scan followed, if positive, by a BM scan. This procedure reduces the cost, the time required for a diagnosis, and the dose of radiation received by the patient.     

What is the RUC?

We describe a crucial but little-known constituent of the Medicare payment system.     

What is the appropriate approach in sex determination of hyoid bones?

The hyoid bone is characterized by sexually dimorphic features, enabling it to occasionally be used in the sex determination aspect of establishing the biological profile in skeletal remains. Based on a sample of 298 fused and non-fused hyoid bones, the present paper compares several methodological approaches to sexing human hyoid bones in order to test the legitimacy of osteometrics-based linear discriminant equations and to explore the potentials of symbolic regression and methods of geometric morphometrics. In addition, two sets of published predictive models, one of which originated in an indigenous population, were validated on the studied sample. The results showed that the hyoid shape itself is a moderate sex predictor and a combination of linear measurements is a better representation of sex-related differences. The symbolic regression was shown to exceed the predictive powers of linear discriminant function analysis when two models based on a logistic and step regression reached 96% of correctly classified cases. There was a positive correlation between discriminant scores and an individual's age as the sex assessment was highly skewed in favour of males. This suggests that the human hyoid undergoes age-related modifications which facilitates determination of male bones and complicates determination of females in older individuals. The validation of discriminant equations by Komenda and ?erný (1990) and Kindschud et al. (2010) revealed that there are marked inter-population and inter-sample differences which lessened the power to correctly determine female hyoid bones.     

CT of the musculoskeletal system: What is left is the days of MRI?

Magnetic resonance imaging (MRI) plays a central role in the modern imaging of musculoskeletal disorders, due to its ability to produce multiplanar images and characterise soft tissues accurately. However, computed tomography (CT) still has an important role to play, not merely as an alternative to MRI, but as being the preferred imaging investigation in some situations. This article briefly reviews the history of CT technology, the technical factors involved and a number of current applications, as well as looking at future areas where CT may be employed. The advent of ever-increasing numbers of rows of detectors has opened up more possible uses for CT technology. However, diagnostic images may be obtained from CT systems with four rows of detectors or more, and their ability to produce near isotropic voxels and therefore multiplanar reformats.     

Lobular carcinoma in situ on core biopsy-what is the clinical significance?

AIM: To retrospectively review the surgical histological findings in all cases where lobular carcinoma in situ(LCIS) was identified on percutaneous core biopsy (CB) performed as part of the Cambridge and Huntingdon breast screening programme.MATERIALS AND METHODS: We retrospectively reviewed all the core biopsies performed in our department for screen detected abnormalities over a 5-year period between 1 April 1994 and 31 March 1999. All patients where LCIS was identified on CB were reviewed. As the significance of LCIS on CB was unclear all went on to surgical excision. We reviewed the clinical and imaging findings, biopsy technique and subsequent surgical histology of each patient.RESULTS: During the study period 60 769 women were invited for screening, of whom 47 975 attended (attendance rate = 79%). Of these, 2330 (4.9%) were recalled for assessment and 749 (1.6%) underwent CB. A malignant diagnosis was obtained in 311 (42%), 211 invasive and 100 in situ lesions. LCIS was identified on CB in 13 (2%). LCIS was the only lesion identified in seven cases. All seven cases subsequently underwent surgical excision. Surgical histology revealed a single case of LCIS and invasive lobular carcinoma. There were two cases of LCIS and DCIS one with a probable focus of invasive ductal carcinoma. In one case LCIS was identified in association with a radial scar. In three of the seven cases LCIS was the only abnormality on both CB and surgical biopsy.CONCLUSION: Our series shows that isolated LCIS on CB following mammographic screening is an infrequent finding, and it may be associated with either an invasive cancer or DCIS. It is therefore advisable that when LCIS is identified on CB, surgical excision of the mammographic abnormality should be performed. Decisions on management should be undertaken in a multidisciplinary setting taking into account clinical and imaging findings.     

What is the complementary role of ultrasound evaluation in the diagnosis of acute appendicitis after CT?

The objective of our study was to estimate the complementary role of ultrasound evaluation in the diagnosis of acute appendicitis after abdominoplevic CT. A total of 104 patients initially underwent abdominopelvic CT before appendix US due to acute abdominal pain. All CT examinations were evaluated retrospectively for the presence of acute appendicitis. The findings of appendix on CT were classified into five categories (definite appendicitis, probably appendicitis, equivocal CT findings for diagnosis of appendicitis, probably not appendicitis, and normal looking appendix). Appendix US images and their radiologic reports were also evaluated retrospectively. Then, CT and US findings were correlated with clinical or pathologic diagnosis. Three all patients with definite appendicitis initially on CT again showed US findings of appendicitis. In the 32 patients of probably appendicitis on CT, US showed normal looking appendix in seven patients (21.8%, 7 of 32) who improved with medical treatment and discharged. In the 16 patients of equivocal CT findings for diagnosis of appendicitis, US showed appendicitis in seven patients (43.8%, 7 of 16) and normal looking appendix in nine patients. In the 12 patients of probably not appendicitis on CT, US showed acute appendicitis in two patients (16.7%, 2 of 12). In the 41 patients of normal looking appendix on CT, US showed acute appendicitis in five patients (12.2%, 5 of 41). US reevaluation enables us to avoid misdiagnosis of appendicitis on CT and improve diagnostic accuracy of acute appendicitis.     

Assessment of chest pain in the emergency room: What is the role of multidetector CT?

Chest pain is one of the most frequent complaints for patients seen in the emergency department. The current article describes the clinical stratification of patients who present to the emergency department with chest pain and discusses imaging options and analysis for these patients. It reviews conventional imaging approaches to assessing chest pain including chest radiography and stress testing. The main discussion focuses on the potential utility use of cross-sectional imaging, particularly multidetector CT, in the evaluation of chest pain in the emergency department.