An assessment of stress analyses in the theory of abfraction

Wedged-shaped lesions at the cemento-enamel junction of teeth have been attributed primarily to biomechanical loading forces that cause flexure and failure of enamel and dentin. This theory, termed abfraction, remains controversial. This review examined studies on mechanical properties of enamel and dentin and studies on bite forces and mastication as background information. Abfraction is based principally on a few early finite element analysis and photoelastic models showing stress concentration at the dental cervical area without actually showing enamel and dentin fracture. However, a review of more recent dental stress analyses has been contradictory. Particularly, analyses of the periodontal ligament and alveolar bone, not modeled in previous studies, have shown that those structures may dissipate occlusal loading forces from the cervical areas. In addition, some models may not fully represent intricate dental anatomy and complex occlusal function. Therefore, the key basis of the abfraction theory may be flawed.     

Cardiovascular autonomic control in myotonic dystrophy type 1: a correlative study with clinical and genetic data

The autonomic nervous system has been evaluated in myotonic dystrophy with contradictory results and its relationship with heart disturbances remains unclear. Twenty-three patients with myotonic dystrophy type 1 were investigated by a battery of six cardiovascular autonomic tests and power spectral analysis of heart rate variability. Although 15 patients (65%) revealed abnormal or borderline results in some tests, only one patient had a definite autonomic damage, as indicated by two or more abnormal tests. As a group, myotonic dystrophy type 1 patients showed a significant reduction of heart rate variability during deep breathing (P < 0.0001). The exclusive involvement of parasympathetic tests suggests that a mild vagal dysfunction occurs in some myotonic dystrophy type 1 patients. The results indicate that such autonomic abnormalities are not: (1) part of a peripheral neuropathy; (2) related to cytosine-thymine-guanine repeat size or breathing pattern. Power spectral analysis showed a reduction of supine low-frequency band, which is, but not exclusively, a marker of sympathetic activity. It was inversely correlated to disease duration (P < 0.04), suggesting a progression as the disease advances. A low-frequency power, recorded after standing, was significantly associated (P < 0.02) with presence of heart involvement. Our findings suggest that a mixed, especially parasympathetic, autonomic dysfunction may occur in myotonic dystrophy type 1, although it is not a major finding. It could play a role in the occurrence of cardiac abnormalities, or increase the risk of sudden cardiovascular events.     

Organization of rat vibrissa motor cortex and adjacent areas according to cytoarchitectonics, microstimulation, and intracellular stimulation of identified cells

The relationship between motor maps and cytoarchitectonic subdivisions in rat frontal cortex is not well understood. We use cytoarchitectonic analysis of microstimulation sites and intracellular stimulation of identified cells to develop a cell-based partitioning scheme of rat vibrissa motor cortex and adjacent areas. The results suggest that rat primary motor cortex (M1) is composed of three cytoarchitectonic areas, the agranular medial field (AGm), the agranular lateral field (AG1), and the cingulate area 1 (Cg1), each of which represents movements of different body parts. Vibrissa motor cortex corresponds entirely and for the most part exclusively to AGm. In area AG1 body/head movements can be evoked. In posterior area Cg1 periocular/eye movements and in anterior area Cg1 nose movements can be evoked. In all of these areas stimulation thresholds are very low, and together they form a complete representation of the rat's body surface. A strong myelinization and an expanded layer 5 characterize area AGm. We suggest that both the strong myelinization and the expanded layer 5 of area AGm may represent cytoarchitectonic specializations related to control of high-speed whisking behavior.     

Non-invasive diagnostic and functional evaluation of cardiac and pulmonary involvement in systemic sclerosis

BACKGROUND: The aim of the present study was to evaluate the role of non-invasive methods in the early detection of pulmonary and cardiac involvement in Systemic sclerosis (SSc) and to identify clinical and/or instrumental patterns of prognostic value. PATIENTS AND METHODS: Twenty female patients affected by SSc (8 with diffuse cutaneous SSc and 12 with limited cutaneous SSc) were enrolled in our study. Cardiac and pulmonary involvement (respiratory function tests and carbon monoxide lung diffusion [DLCO], chest radiography, high resolution computed tomography [HRCT] and lung perfusion magnetic resonance) were evaluated. RESULTS: All 18 patients studied with respiratory function tests showed a significant reduction of DLCO. HRCT was considerably more sensitive than traditional chest radiography (59% versus 28%; p<0.05). Lung perfusion MRI revealed normal findings in 15 patients. Abnormal lung perfusion MRI results were found only in 3 patients. Angina pectoris with electrocardiographic and scintigraphic ischemic changes, severe regional wall motion abnormalities and complex arrhythmias seemed to be associated with poor prognosis. CONCLUSION: Taken together these results indicate that a pulmonary involvement occurs both in limited and in diffuse cutaneous SSc patients and develops, in 83% of the cases, without any regional lung perfusion abnormality. Furthermore, cardiac involvement is detected in 65% of the cases as a consequence of a range of noxious events including myocardial ischemia, fibrosis and pressure overload which may result in ventricular dysfunction and arrhythmias. Lung perfusion MRI should be considered as a complementary diagnostic method for the functional evaluation of these symptoms in systemic sclerosis.     

Cadmium concentration in maternal and cord blood and infant birth weight: a study on healthy non-smoking women

The aim of our study was to measure, at delivery, maternal and cord blood cadmium levels (by means of atomic absorption spectrometry) in 45 healthy non-smoking pregnant women exposed to a low cadmium challenge, and to evaluate the relationship between these cadmium levels and the birth weight of the infants. Our results showed fairly low cadmium levels in maternal blood, in accordance with the fact that all women enrolled in this study lived in areas with low toxic metal contamination and that they did not smoke during their pregnancy. Furthermore, a highly significant direct correlation was found between maternal and cord blood cadmium concentrations. Since cadmium concentration appeared of the same order of magnitudine both in cord and maternal serum, one could speculate that cadmium is transferred easily from the mother to the fetus through the placenta. Finally, we found that birth weight is inversely correlated with maternal and cord blood cadmium concentrations; thus birth weight might be negatively influenced by cadmium levels as a result of the toxic effects of the metal on the placenta. Although preliminary, our data show that (also not-predictable) prenatal exposure to even low cadmium levels might be a risk factor for developmental impairment in infants.     

Outpatient Parenteral Antibiotic Therapy (OPAT): the Italian registry

In the early eighties, in the US the advantages (reduced costs, no hospitalisation trauma in children, no immobilization syndrome in elderly, reduction of nosocomial and acquired infections by multi-resistant organisms) of OPAT were identified and suitable therapeutic programs were established. Following the US experience, other countries set up their own OPAT programs which vary considerably from country to country because of different ways in which infections are managed in different parts of the world and because of different reimbursement systems. In order to understand the ways of managing OPAT and its results, a National OPAT Registry was set up in 1999 in Italy belonging to a wider International OPAT database, which collects data also from USA, Canada, Spain, Uruguay and Argentina. Up to now 396 patients and as many antibiotic courses have been included in the National Registry by eight different centres. The analysis of data permits to get information about the criteria of patient's selection, treatment (route of administration, site of care, choice of antibiotic, dosage and duration), outcomes and possible side-effects. Italian results offer a quite peculiar picture of OPAT in this country when comparing data with those of other countries. In contrast with other countries where soft tissue infections and osteomyelitis are the most frequent diagnoses for including patients in OPAT programmes, in Italy pneumonia and bronchitis are the top two amenable infections. Ceftriaxone, Teicoplanin and Amikacin are absolutely the top three antibiotics selected for OPAT in Italy which confirm that a single daily dose regimen represents a great advantage in terms of compliance. Finally, a large percentage of antibiotic courses (50%) are carried out by using the i.m. administration route, which is very unusual in other countries. OPAT Registry is still ongoing and it will give us more detailed information in the future about the management of infections in the outpatient setting, but it already permits to define an actual picture of OPAT in our country and/or to compare and correlate data and information from different countries.     

MRI lung perfusion 2D dynamic breath-hold technique in patients with severe emphysema

BACKGROUND: Our aim was to prospectively evaluate a semi-quantitative pulmonary perfusion MR technique using a breath-hold 2D dynamic sequence in patients with severe pulmonary emphysema. MATERIALS AND METHODS: Thirty patients with severe emphysema were studied with pulmonary perfusion MRI. Results were compared with those obtained through lung scintigraphy, considered as the gold standard technique. We used Fast Field Echo (FFE) pulse sequences in the coronal and sagittal planes, with paramagnetic contrast agent administration. Ten healthy volunteers were studied as the control group. Three thoracic radiologists independently reviewed all the subjects, evaluating the site and entity of perfusional defects. Peak intensity and apparent mean transit time were calculated. RESULTS: MRI showed high sensitivity (86.7%) and good specifity (80.0%) in detecting perfusional defects. We observed lower peak signal intensities in emphysematous regions. CONCLUSION: Lung perfusion MR is a potential alternative to Nuclear Medicine in the evaluation of severe pulmonary emphysema.