Réduction des effets de la respiration en imagerie TEP pulmonaire par une acquisition synchronisée à la respiration associée à une TDM en apnée

Respiratory motion causes a spread of lesion uptake over a larger area in Positron Emission Tomography (PET) images for moving structures. When CT images are used for attenuation correction of emission data, this motion may alter the quantization of PET images. We present the clinical results of a respiratory-gated PET processing “CT-based” method, which aims to improve PET-CT coregistration by using an additional breath-hold CT (BH-CT). The CT-based protocol consisted in a 10-min List Mode respiratory-gated PET acquisition, followed by an end-expiration BH-CT acquisition. During these two examinations, the respiratory signal was recorded continuously. Eleven pulmonary lesions were studied. Patients underwent both a standard clinical PET protocol (free breathing) and the CT-based protocol. The respective performances of the CT-based and clinical PET methods were evaluated by comparing the distances between the lesions’ centroids on PET and CT images. SUV_MAX (Standardized Uptake Value) and volume variations were also investigated. The CT-based method showed a significant reduction (p = 0.049) of centroid distances (mean relative change versus standard method: 49%). We also noted a higher SUV_MAX (mean change: 39%). Lesion volumes were significantly lower (p = 0.026) in CT-based PET volumes (mean change: 43%) compared with standard ones. The CT-based method improves PET-CT coregistration of pulmonary lesions. This protocol should lead to more accurate attenuation correction and thus improve SUV measurement.     

Insuffisance rénale chronique : de la maladie osseuse à la maladie osseuse et vasculaire

The accelarated atherosclerosis occurring in patients with chronic renal failure (CRF) is a well-known complication since the beginning of dialysis. The relationship between vascular lesions and phosphocalcic abnormalities is a more recent concept. The relationship between increase in phosphate × calcium product and cardiac valvular calcifications was demonstrated in 1980. The relationship between high serum phosphate levels and mortality was shown in 1998. The strong prevalence of coronary calcifications in CRF patients was shown in 1996. In 2000, the association between these calcifications and the oral dose of calcium was strongly suggested. Thereafter, the mechanism of these calcifications appeared much more complex, involving hypercholesterolemia, inflammation, and other factors. The relationships between hyperparathyroidism and mortality were shown during the years 2000. There is also an association between hypoparathyroidism and mortality in dialysis patients but not in CRF patients before the dialysis stage. Another new concept is the discovery of a relationship between vitamin D deficiency, very frequent is CRF patients, and mortality. Treatment with active 1,25(OH)D is associated with a better survival. There is also an new interest in treatment with the 25(OH)D form since the enzyme 1-alpha-hydroxylase, which is responsible for its transformation in active form, is present in multiple organs.     

Eléments d'observation sur la cinématique,la dynamique et l'énergétique de la locomotion dans le courant chez une larve de Trichoptère à fourreau

Observations on the kinetics, dynamics and energetics of the locomotion in the current of a case-bearing Trichoptera larva. The locomotion of Trichoptera larvae was studied by means of films. It follows a sequence similar to that usually observed in walking insects, with protraction of legs from behind to forward (Fig. 1). The walking is slow. In a current, the sequence of protraction is often modified by supplementary protractions of the anterior and middle legs (exploration or skidding). The locomotion includes phase a (advance of the body) and phase b (case towing, with protractcion of posterior leg). These two phases are more clearly separated in a current than with a force (Fig. 4, 5). These two phases agree perfectly with the basic pattern described by Denis (1968) for the larval case construction. The current causes a decrease in the mean locomotion speed (L_m) by shortening and above all separating the towing phases, which are the only moments for the rapid advance of the case (Tabl. I). Turbulent water causes the case to vibrate and these vibrations vary in amplitude (from 0.1 to 2 mm) with water velocity, but not significantly. The frequency of the vibrations does not seem to go above 15 oscillations per second (above 20 cm/s), but it is possible that higher frequencies could not be correctly registered at 64 pictures per second. These vibrations may be the cause of the higher activity in the current than under a traction force without vibrations (Bournaud, 1973). The coefficient of resistance (C_w) of the larva-case complex is high (near 0,89) at velocities above 55 cm/s, but is much higher at velocities below 55 cm/s (Fig. 7). So the case of M. testacea is better adapted to high current velocities. The 55 cm/s limit also corresponds to the velocity for changes in aspects of the behaviour of this species: rate of activity, beginning of rheokinesis stage, disappearance of negative locomotion. The minimum quantity of energy necessary for regular locomotion is from 2.6 to 3.3 × 10⁻³ kgm/s/kg fresh weight, at the rheokinesis stage (absolute maximum: 10.2 × 10⁻³ kgm/s/kg). The real energetic expenditure (R_g), including the rate of activity, is much lower (0.03 to 1 × 10⁻³ kgm/s/kg), while the energetic expenditure during the towing phases (instantaneous rheokinesis) is much higher (up to 50 × 10⁻³ kgm/s/kg) (Tabl. II). However all these values are lower than those found in the animal kingdom, and the mean traction strength of M. testacea is very high (up to 29 times the larval weight). Therefore this species uses more of its energy in traction than in speed, the opposite to the situation in fishes. It is an ethological adaptation to life in a current, reinforced by the necessity of pulling a case which increases the force of the current. The available energy E obtained by the consumption of oxygen is 86.3 × 10⁻³ kgm/s/kg in still water. It is larger than (or equal to) the instantaneous rheokinesis (R_i) in the current. Only part of the energy E is transformed into muscular energy measured by R_i. Since a 30 cm/s current produces an increase in metabolism of about 30 × 10⁻³ kgm/s/kg, the needs for muscular energy R_i increase too fast to be covered only by the basal level of metabolism in still water. In fact, only a part of the muscular energy R_i (about 1 to 3%) is transformed into strictly locomotion R_g, so that this energy requirement needs less than 1/1000 of the energy obtained by metabolism in still water (Tabl. II).     

Contributions à la biochimie du ver à soie—XXX. Biosynthèse de tréhalose et de glycogène à partir de glucose-1-phosphate

• 1.1. When injected into silkworms in the middle of the fifth larval instar, labelled G-1-P is principally used for the synthesis of hemolymph trehalose.
• 2.2. Glycogen synthesis from the same source in the fat body proceeds more rapidly in undernourished larvae than in those fed normally.
• 3.3. Owing to the poor incorporation of the radioactivity in the glycogen and especially in the trehalose of the fat body, it is suggested that the trehalose could be synthesized from pyruvate elsewhere than in the fat body, and that the biosynthetic pathway of trehalose from pyruvate does not necessarily pass through glycogen.
• 4.4. The synthesis of trehalose and glycogen, as well as the hydrolysis of glycogen, could be controlled, directly or indirectly, by the variations of the trehalose level in the hemolymph.
• 5.5. The gluconeogenetic pathways in the silkworm are discussed and presented in the form of a partially hypothetical figure.

     

Mesure de la décroissance de la fluorescence polarisée de la γ-globuline-1-sulfonyl-5-diméthylaminonaphtalène

The decays of the two polarized components of the fluorescence emitted by the rabbit 5-dimethylaminonaphthalane-1-sulfonyl-γ-globulin, are measured at pH 8. The time course of the emission anisotropy is calculated from these measurements. The resulting curve is interpreted in terms of two relaxation processes. One of them with a relaxation time of 370 nsec, and a contribution of 65%, is ascribed to the rotation of the whole molecule, while the other one, caracterized by a short relaxation time of 23 nsec, must come from internal Brownian motions involving the rotation of a globular part of the molecule. One concludes that there is some flexibility in the native form of the γ-globulin molecule.     

Une nouvelle faune de vertébrés continentaux,associée à des artefacts dans le Pléistocène inférieur de l’Hérault (Sud de la France), vers 1,57 Ma

A new vertebrate fauna associated with lithic artefacts from the Early Pleistocene of the Hérault Valley (southern France) dated around 1.57 Ma. Some lithic artefacts associated with an Early Pleistocene (Upper Villafranchian) vertebrate fossil assemblage have been found from a quarry exploited for basalt in the lower Hérault Valley (Languedoc, southern France) at the Lézignan-le-Cèbe locality. A preliminary patrimony expertise led us to identify about 20 vertebrate taxa, and the autumnal rainfalls revealed the presence of roughly 30 lithic artefacts of “pebble culture” type. A basalt layer dated at 1.57 My directly overlies the fossiliferous level, extends along the little hill (locus 2) yielding artefacts. These new promising data offer new perspectives to improve our understanding of Early Pleistocene ecosystems (and possibly ancient hominin occupation) of southern Europe.     

Mise en évidence et évaluation des “moyennes molécules” de la taille de la vitamine B12 présentes dans les liquides biologiques de sujets normaux et de patients urémiques

Determination of “middle molecules” presenting vitamin B₁₂ molecular size in normal and uremic body fluidsUremic solutes with the molecular size of vitamin B₁₂ are assumed to be toxic. An analytical method is proposed to detect and separate these solutes in body fluids using two combined techniques: gel filtration on Sephadex G-15 and ion-exchange chromatography on DEAE-Sephadex A-25. The vitamin B₁₂ molecular size has been localized by ultrafiltration through membranes with a defined cut-off. Normal and uremic body fluids (urine, plasma, hemodialysis fluid) have been separated into 9 ultraviolet-absorbing peaks (a to i) by high-speed gel filtration. Peaks b and e present the molecular size of vitamin B₁₂, 10–15 Å molecular diameter in pH 7 aqueous solution. Peak b, which correlates with uremic neuropathy, is separated into 6 sub-peaks (b₁ to b₆) by ion-exchange chromatography, sub-peak b_4.2 is the only one to correlate with uremic neuropathy. The coefficient of variation in the integrated area of a single peak is 16%. This method gives the chromatographic profile of the vitamin B₁₂ molecular size content from 500 μl of uremic plasma or 100 μl of normal urine within one hour.     

Les lésions de l’urètre associées à une fracture des corps caverneux. A propos d’une série de 4 cas et revue de la littérature

Introduction

Urethral injury associated with corpora cavernosa fracture is a relatively uncommon form of urological trauma. Early diagnosis and immediate surgical repair are essential.

Patients and methods

Between January 1990 and December 2004, a total of 4 male patients with urethral injury associated with fracture of the corpora cavernosa were retrospectively studied from a series of 96 cases of penile fracture.

Results

The mean age of the patients was 36.5 years (range: 27–45 years). Urethral bleeding was noted in all patients. Immediate surgical repair via a penile circular subcoronal incision was performed in all cases. Two partial urethral injuries associated with a unilateral corpus cavernosum lesion were identified. In the other cases, total urethral injury was associated with bilateral rupture of the corpora cavernosa. The tunica albuginea defect was closed and the urethral laceration repaired over a urethral catheter. With a mean follow-up of 2.5 years, 2 short urethral strictures were observed and were managed non-operatively with good outcome.

Comments

Secondary urethral lesions associated with corpora cavernosa fracture most frequently affect young adults. In North African countries, forced self-manipulation of an erect penis is the most frequent cause, but the associated urethral lesion is usually related to vaginal intercourse. The diagnosis can generally be made on the basis of history and physical examination alone. Blood at the meatus or haematuria or voiding difficulties suggest associated trauma to the urethra [4]. Additional imaging examinations are rarely required. The standard treatment is prompt surgical exploration, evacuation of haematoma, and primary repair of the urethral and corpora cavernosa defects. Late complications after surgical repair are penile curvature and pain during coitus. They are usually attributable to a residual fibrotic area.

Conclusion

Urethral injury associated with corpora cavernosa fracture usually has typical signs. The mechanism of trauma is very suggestive. Early surgical treatment is the only guarantee of a satisfactory functional result.