Improved TV-CS Approaches for Inverse Scattering Problem.

Total Variation and Compressive Sensing (TV-CS) techniques represent a very attractive approach to inverse scattering problems. In fact, if the unknown is piecewise constant and so has a sparse gradient, TV-CS approaches allow us to achieve optimal reconstructions, reducing considerably the number of measurements and enforcing the sparsity on the gradient of the sought unknowns. In this paper, we introduce two different techniques based on TV-CS that exploit in a different manner the concept of gradient in order to improve the solution of the inverse scattering problems obtained by TV-CS approach. Numerical examples are addressed to show the effectiveness of the method.

Comparison of cutaneous termic response to a standardised warm up in trained and untrained individuals.

AIM: Warm up prior to exercise induces an increased production of metabolic heat, which triggers the thermoregulatory system to initiate heat loss mechanisms. Variations in cutaneous tissue temperature have been already reported in trained subjects, by means of high resolution thermal imaging. Purpose of this paper was to quantitatively evaluate, by means of infrared thermography, the differences in the cutaneous temperature among trained and untrained subjects. METHODS: Forty male volunteers performed a standard warm up exercise on a stationary cycle, divided in three steps: 1) 0-5 minutes at 100 Watt; 2) 5-10 minutes at 130 Watt; and 3) 10-15 minutes at 160 Watt. Thermal images from thorax and upper limbs were collected during the exercise. Heart rate was also measured. RESULTS: In comparison to baseline, trained subjects exhibited a significant temperature reduction in the third step (trunk, P<0.01; upper limbs, P<0.009), while no difference was observed in untrained subjects. In the comparison between groups, a statistically significant difference was observed in both regions of interest, in the second (trunk, P<0.01; upper limbs, P<0.02), and in the third step (trunk, P<0.0002; upper limbs, P<0.0008). During the whole exercise, heart rate increased progressively in all participants, but more markedly in untrained subjects. CONCLUSION: Cutaneous thermoregulatory response differs among trained and untrained participants. Infrared thermal imaging is useful in detecting these differences, providing additional data to the physiological evaluation of subjects performing sport activities.

Functional infrared imaging of paroxysmal ischemic events in patients with Raynaud's phenomenon.

The use of thermal infrared (IR) imaging together with the study of the thermal recovery from a controlled cold challenge has been proposed in the diagnosis and follow-up of therapeutic response of Raynaud's Phenomenon (RP) and Systemic Sclerosis (SSc). The controlled cold challenge test usually performed during IR investigations may induce a RP in patients with the latter condition. In our Institution we routinely perform capillaroscopy and thermal IR to follow-up SSc patients. In this paper, we describe the thermal recovery patterns shown by two SSc patients (a 40 year-old male with diffuse variant of SSc and a 71 year-old female with a limited variant of SSc) who presented ischemic and paroxysmal RP attack while recovering from the routine controlled cold challenge test. During RP attack, the cutaneous temperature of some fingers continued to decrease for some minutes even after the cessation of the cold stress. To the best of our knowledge, to date, no literature report has documented the thermal behaviour of SSc patients' fingers which occasionally present ischemic and paroxysmal response. Triggering of ischemic RP attack appears to not rely only on morphological and structural finger impairment, but also upon other aspects, like the emotional attitude of the subject and the possible discomfort experienced with the proceeding of the functional cold stress test.

Comparison of thermal infrared and laser doppler imaging in the assessment of cutaneous tissue perfusion in scleroderma patients and healthy controls.

In this study we propose a non-invasive method to calculate blood flow by means of thermal infrared imaging and bio-heat transfer modeling. The method is able to provide high time-resolution series of cutaneous blood flow images with the same spatial resolution of the thermal images. The method was tested against a standard laser Doppler imaging system, which to date is considered the gold standard for non-invasive assessment of cutaneous blood flow, on both healthy subjects and patients suffering from systemic sclerosis (SSc; a pathological condition with microvessel endothelium injury). Twenty healthy subjects and twenty SSc patients simultaneously underwent laser Doppler and thermal imaging of the dorsum of the hand. A linear correlation between perfusion values obtained with the two methods was found for the healthy control group (R = 0.85, Pearson Product Moment Correlation). A significant correlation was not observed for the SSc patient group. The results of this study suggest that combined laser Doppler, thermal imaging and bio-heat transfer modeling could effectively discriminate between healthy vs. impaired conditions of the cutaneous tissue thermal properties and cutaneous vasculature. Such method, in addition to providing a potential effective imaging-based tool for a variety of biomedical and clinical applications ranging from diagnostics to treatment follow-up, may help the understanding of the morphological and functional impairment secondary to the disease. The thermal imaging-based method provided faster and better time-resolved imaging of cutaneous perfusion than standard laser Doppler techniques as the thermal cameras can provide up to 100 complete 524 x 524 pixel images per second, thus allowing real time monitoring of tissue perfusion rates.

Combined thermal and laser Doppler imaging in the assessment of cutaneous tissue perfusion.

Infrared thermal imaging permits to non-invasively obtain, throughout bioheat models using a series of thermal images, the cutaneous blood perfusion. Laser Doppler imaging measures blood flow in the very small blood vessels of the microvascular network. In this paper, we compare findings from the two methods on a set of healthy volunteers. Cutaneous blood perfusion values obtained from thermal imaging correlate to those obtained by means of Laser Doppler imaging with the advantage of a better time resolution. Combined imaging of the two modalities may provide a useful tool for monitoring diseases affecting cutaneous tissue and/or microcirculation.

[Glomerulo-tubular balance in diabetes mellitus: molecular evidence and clinical consequences]. / Bilancio glomerulo-tubulare nel diabete mellito: evidenze molecolari e conseguenze cliniche.

Diabetes mellitus is fast becoming a world epidemic. About one-third of individuals with diabetes, after 10 yrs, develop diabetic nephropathy, the first cause of end-stage kidney disease. The evolution of diabetic nephropathy can be considered in three stages: glomerular hyperfiltration, microalbuminuria (30-300 mg/24 hr) and proteinuria (>300 mg/24 hr). This study was designed to investigate the tubular basis of glomerular hyperfiltration in early diabetes mellitus. Diabetes was inducted in rats with i.p. streptozotocin (65 mg/kg bw) for 6 days. At the end of the treatment, the glomerular filtration rate (GFR), measured by inulin clearance, had substantially increased in diabetic rats compared with controls. Quantitative polymerase chain reaction (PCR) and Western blot analysis reveal that in diabetic rats compared with controls, mRNA and protein abundance was higher for type 3 sodium/hydrogen exchanger (NHE3) in proximal tubule and ascending limbs of Henle's loop, and higher for bumetanide-sensitive sodium-potassium-2 chloride cotransporter (NKCC2) in ascending limbs of Henle's loop. Western blot analysis confirmed the PCR results. Finally, the abundance of á -ENaC protein was unchanged in diabetic rats compared to controls. These results show that the primary sodium reabsorption increase in proximal tubule reduces salt concentrations at the macula densa. This elicits a tubuloglomerular feedback-dependent increase in single nephron GFR.

Undiagnosed coeliac disease does not appear to be associated with unfavourable outcome of pregnancy.

BACKGROUND: In a previous hospital based study, we suggested that undiagnosed coeliac disease has a prevalence, among pregnant women, of 1:80, and is a cause of unfavourable outcome of pregnancy. AIMS: In order to confirm or dismiss this hypothesis, which has significant public health implications, we carried out a large population based study on a stratified sample from the whole Campania region. PATIENTS: During the period of the study, 5345 women were admitted to the OBS-GYN wards regional network: 5055 (95%) were enrolled in the study. METHODS: Antihuman IgA class antitissue transglutaminase (TGASE) antibodies were tested by an ELISA method. Endomysial antibodies (EMA) were investigated on thin sections of human cord blood by an immunofluorescence test. The HLA class II DQA1*0501/DQB1*02 and DQA1*0301/DQB1*0302 haplotypes were assessed using the Eurospital Eu-DQ kit. Duodenal biopsy was not considered feasible by the ethics committee for pregnant women near delivery. RESULTS: Fifty one of 5055 patients had confirmed positive results. We added to these 12 women with known coeliac disease, giving a prevalence rate for coeliac disease of 1:80 (exactly the value observed during the first study). Comparing the 51 TGASE positive with 4997 negative women, we did not observe an excess risk of abortion, premature delivery, small birth weight, or intrauterine growth retardation. Anaemia was more frequent in cases than controls. CONCLUSIONS: Undiagnosed coeliac disease is frequent among pregnant women (>1%) but is not associated with an unfavourable outcome of pregnancy.

Raynaud's phenomenon: Infrared functional imaging applied to diagnosis and drug effects.

A non-invasive, innovative approach to the study of Raynaud's Phenomenon is proposed. A group of patients, with respect of a control group, underwent a simultaneous assessment of thermal properties of all ten fingers using infrared functional imaging (IRFI). The assessment highlighted a quite different behaviour between patients with Primary- (PRP) and those with scleroderma - Raynaud's Phenomenon (SSc) and, compared with other existing techniques, seems to be an objective and effective tool to discriminate between PRP and RP secondary to SSc. 18 healthy volunteers (Norm), 20 Primary Raynaud's Phenomenon (PRP) and 20 Secondary Scleroderma (SSc) patients were studied subsequently to clinical evaluation and nail fold capillaroscopy. High-resolution infrared imaging of finger re-warming processes, immediately after a 2 min cold stress, allowed to identify objective parameters. Temperature integral Q (the temperature evaluation of the area under the time-temperature curve along the re-warming period) provided particularly effective figures in describing thermal properties of the fingers. Grand average Q values were (383.4 ∓ 12.5) °C×min, (502.9 ± 88.1) °C×min and (1022.0 ± 110.2) °C×min for the PRP, SSc and Normal groups, respectively. Separate evaluation of the temperature integral for each finger leads to very similar results for the fingers of all the PRP patients; a different thermoregulatory response was observed in SSc patients. The sensitivity of the method in order to distinguish healthy from ill fingers was 100%. The specificity in distinguishing SSc from PRP was 95%. In addition, IRFI parameters provided a better understanding of the impaired control of the finger's temperature in PRP and SSc with respect to the Normal group. This pilot study also applied IRFI for the measurement of drug effects in patients with Raynaud's Phenomenon. Sixteen out of twenty SSc patients were tested in a single 1-hour session of N-acetylcysteine infusion. IRFI clearly documented a significant increase of face and hands temperature during the drug administration. The grand average value of the finger's temperature after the 1 hour NAC administration was (29.6 ± 3.7) °C, while its value before was (27.9 ± 3.7) °C (p<0.001). N-acetylcysteine seems to act as a vasodilator in patients with Raynaud's phenomenon secondary to systemic sclerosis (scleroderma).

Seasonality of marriages and ecological contexts in rural communities of central-southern Italy (Abruzzo), 1500-1871.

The seasonality of 27,705 marriages celebrated in a four century span in the Province of Teramo (Abruzzo, Italy) was analyzed to identify the presence of a long-term pattern related to the prevailing subsistence activity and the main factors affecting it. The results show general agreement in all centuries with the agricultural patterns of other lowland or south-central Italian groups (Piedmont, Veneto, Liguria, Emilia Romagna, Tuscany, Latium, Compania, Apulia) and Mediterranean regions (Spain, France), although with some differences. Religious factors strongly affected the timing of marriage only during Lent. Of interest is the progressive increase through the centuries of marriages in the summer-autumn months, associated with a decrease in January and February. This suggests the passage from a summer migration system to a rural sedentary system with occasional seasonal work.

The study of steady magnetic fields associated with primary and secondary ST shift in ischaemic rabbit hearts.

The study of injury potentials associated with DC currents that generate the primary or secondary ST shifts during cardiac ischaemia is possible only through the invasive technique of the DC electrogram. Clinical surface ECG recordings are AC coupled and cannot be used. This paper reports the use of non-invasive and unshielded magnetocardiographic measurements to evaluate the DC injury currents associated with ST shifts during coronary artery occlusions in the isolated rabbit heart. The effect on the magnetic ST shift is studied under different ischaemic conditions including regional ischaemia, global ischaemia, global ischaemia following long periods of regional ischaemia, regional ischaemia after repeated episodes of reversible global ischaemia, and bilateral regional ischaemia. Recording of DC magnetic fields allows the characterization of primary and secondary ST displacement for each induced ischaemic condition. Our measurements show that the ST shift starts earlier when inducing ischaemia in hearts previously subjected to ischaemic episodes than in hearts where the ischaemia was produced for the first time.

Detection and counting of specific cell populations by means of magnetic markers linked to monoclonal antibodies.

We report on experiments aimed at the assessment of a new method for cell marking. This method combines superparamagnetic particles, commonly used for cell separation, linked to monoclonal antibodies, and biomagnetic instrumentation featuring an extremely high magnetic field sensitivity. The final goal of the method is to locate and estimate specific cell populations in the human body. In this experiment, quantitative features of the method are evaluated in vitro with lymphocytes and carcinoma cells. Comparison between estimation and direct counting of cells is quite satisfactory and motivates further development of the technique.

Isotopomer analysis of citric acid cycle and gluconeogenesis in rat liver. Reversibility of isocitrate dehydrogenase and involvement of ATP-citrate lyase in gluconeogenesis.

We conducted an extensive mass isotopomer analysis of citric acid cycle and gluconeogenic metabolites isolated from livers of overnight fasted rats perfused with 4 mM glucose, 0.2 mM octanoate, 1 mM [U-13C3]lactate, and 0.2 mM [U-13C3]pyruvate, in the anterograde or retrograde mode. In both perfusion modes, two distinct isotopomer patterns were observed: (i) those of phosphoenolpyruvate, glucose, malate, and aspartate and (ii) those of citrate, alpha-ketoglutarate, glutamate, and glutamine. Key citric acid cycle parameters and, hence, rates of gluconeogenesis, calculated (Lee, W.-N.P. (1989) J. Biol. Chem. 264, 13002-13004 and Lee, W.-N.P. (1993) J. Biol. Chem. 268, 25522-25526) from our mass isotopomer data did not only vary, but lead to conclusions inconsistent with Lee's citric acid cycle model. Compared to lactate and pyruvate uptake, which sets an upper limit to glucose production, rates of gluconeogenesis calculated (i) with the phosphoenolpyruvate and citrate data were similar, but those calculated (ii) with the glutamate data amounted to only 60%, which is unlikely. All these conclusions are independent of the perfusion modes. We provide evidence that the following processes contribute to the observed labeling discrepancy: (i) the reversibility of the isocitrate dehydrogenase reaction and (ii) an active citrate cleavage pathway for the transfer of the oxaloacetate carbon skeleton from mitochondria to the cytosol. Also, a good fit of our labeling data was obtained with a model of citric acid cycle and gluconeogenesis which we developed to incorporate the above reactions (Fernandez, C.A., and Des Rosiers, C. (1995) J. Biol. Chem. 270, 10037-10042). The following conclusions can be drawn from the calculated reaction rates: (i) about half of the lactate conversion to glucose occurs via the citrate cleavage pathway, (ii) the flux through the reversal of the isocitrate dehydrogenase reaction is almost as fast as that through the citrate synthase reaction, and (iii) the flux through citrate synthase and alpha-ketoglutarate dehydrogenase is 1.6- and 3.2-fold that through pyruvate carboxylase, respectively.

Rates of gluconeogenesis and citric acid cycle in perfused livers, assessed from the mass spectrometric assay of the 13C labeling pattern of glutamate.

Absolute rates of gluconeogenesis and of the citric acid cycle were assessed in livers isolated from 24-h starved rats, perfused with physiological concentrations of [3-13C]lactate and [3-13C]pyruvate +/- 0.2 mM octanoate. Calculations are based on (i) the 13C-labeling pattern of glutamate determined by gas chromatography-mass spectrometry combined with isotopomer analysis, (ii) substrate balance, and (iii) equations developed by Magnusson et al. (Magnusson, I., Schumann, W. C., Bartsch, G. E., Chandramouli, V., Kumaran, K., Wahren, J., and Landau, B. R. (1991) J. Biol. Chem. 266, 6975-6984) based on a citric acid cycle model proposed by Katz (Katz, J. (1985) Am. J. Physiol. 248, R391-R399). Glutamate, isolated from liver extracts, is enzymatically or chemically converted to gamma-aminobutyrate, alpha-hydroxyglutarate, isocitrate, and glutamine before mass spectrometric analysis. General equations have been developed ("Appendix I") to determine the isotopic enrichment of each carbon of glutamate from the isotopic enrichment of fragments obtained from the mass spectra of trimethylsilyl or t-butyldimethylsilyl derivatives of glutamate and of derived compounds ("Appendix II"). In the presence of octanoate, (i) the rate of the citric acid cycle decreases from 0.25 to 0.13 mumol/min x g wet weight which are one-third and one-sixth of the rate of pyruvate carboxylation, and (ii) the rate of gluconeogenesis increases from 0.65 to 0.83 mumol/min x g wet weight. The rate of pyruvate carboxylation is 13 and 34-fold faster than that of pyruvate dehydrogenation in the absence or presence of octanoate, respectively. The rate of oxaloacetate to fumarate interconversion is at least six times greater than that of the citric acid cycle. Our data closely agree with those obtained by Magnusson et al. who used a non-invasive "chemical biopsy" of the human liver and support the use of labeled lactate and/or pyruvate for tracing hepatic metabolism in vivo.

Measurement of segmental transit through the gut in man. A novel approach by the biomagnetic method.

The techniques commonly used to evaluate the transit of contents through the gut feature some limitations for being either inaccurate, invasive, inconvenient, or potentially dangerous for the subjects. Aim of this study was to establish a safe, noninvasive and accurate technique for the measurement of segmental oroanal transit time. We localized an orally ingested magnetic marker by means of a biomagnetic instrumentation that allows us to identify in a three-dimensional pattern the position of a biomagnetic source inside the body. The biomagnetic localizations were compared with the anatomical data obtained by magnetic resonance imaging investigations. The study was performed in 12 healthy subjects, and scans were taken every hour up to the arrival of the marker into the cecum; thereafter, scans were taken every 4 hr up to the elimination of the marker. In 99% of the isofield maps obtained from each field scan, the marker was localized within the bowel walls. The mean oroanal transit time was 56 +/- 5 hr, the mouth-to-cecum transit time was 13 +/- 1.7 hr, and the total colonic transit time was 43.5 +/- 5 hr (mean +/- SEM). Segmental colon transit did not show major differences among the regions considered, although most of the time was spent in the right colon. In fact, a good correlation was found between transit time through the right colon and oroanal and total colonic transit (r = 0.77, P < 0.02, r = 0.79, P < 0.02 respectively). In conclusion, this method might be a safe alternative to the techniques presently used in the clinical setting for the measurement of intestinal transit.

Measurement of gastrointestinal transit time by means of biomagnetic instrumentation: preliminary results.

The measurement of gastrointestinal transit time, GITT, is of particular interest in the study of gastrointestinal activity and in the diagnosis of some pathologies. In the present work we report the measurements of GITT obtained by applying the biomagnetic method.