SMC1 involvement in fragile site expression

Common fragile sites have been involved in neoplastic transformation, although their molecular basis is still poorly understood. Here, we demonstrate that inhibition of the SMC1 by RNAi is sufficient to induce fragile site expression. By investigating normal, ATM- and ATR-deficient cell lines, we provide evidence that the contribution of SMC1 in preventing the collapse of stalled replication fork is an Atr-dependent pathway. Using a fluorescent antibody specific for gamma-H2AX, we show that very rare discrete nuclear foci appear 1 and 2 h after exposure to aphidicolin and/or RNAi-SMC1, but became more numerous and distinct after longer treatment times. In this context, fragile sites might be viewed as an in vitro phenomenon originating from double-strand breaks formed because of a stalled DNA replication that lasted too long to be managed by physiological rescue acting through the Atr/Smc1 axis. We propose that in vivo, following an extreme replication block, rare cells could escape checkpoint mechanisms and enter mitosis with a defect in genome assembly, eventually leading to neoplastic transformation.     

Abnormal α-aminoadipic acid excretion in a newborn with a defect in platelet aggregation and antenatal cerebral haemorrhage

Summary -Aminoadipic acid (AA) is an intermediate in lysine metabolism. We report a new case with AA excess in urine and plasma, without -ketoadipic acid, in a full-term male child born to unrelated parents; he presented at 24h of life with seizures that failed to respond to phenobarbital, clonazepam, and Vigabatrin and death occurred on the 38th day of life. Brain imaging suggested antenatal haemorrhage. Small quantities of AA were also detected in the blood and urine of both parents and a healthy brother, all three of whom exhibited the same defect in platelet aggregation as the deceased child. Both parents had decreased levels of plasma neopterin, a finding that might be related to the immunodeficiency described in other cases.     

Synovial healing in reconstructed cruciate ligaments. Our personal experience compared in single interventions and combined reconstructions

INTRODUCTION: The healing process of tendon grafts used in cruciate ligament reconstruction is called ligamentization. The tendon structural architecture changes progressively into the histological appearance of normal ligament. Amiel and Clancy have demonstrated that this process is time-dependent in anterior cruciate ligament (ACL) reconstruction, the tendon graft taking one year to become similar to a normal cruciate ligament. Three different maturation phases of anterior cruciate graft ligamentization can be seen at MRI: periligamentous proliferation, intraligamentous proliferation and definitive healing. We report our MR findings in the reconstruction of single ACL, posterior cruciate ligament (PCL), and of both ACL and PCL. MATERIAL AND METHODS: January 1995 to January 1999 we selected 60 patients submitted to arthroscopic cruciate ligament reconstruction. The ACL was reconstructed with the patellar tendon in 22 cases and the PCL in 23; fifteen patients underwent double reconstruction of ACL, with hamstring tendons, and PCL, with patellar tendons. Fifty-five patients were followed-up with MRI: 45 with a dedicated permanent magnet (Artroscan, Esaote Biomedica, Genoa, Italy) and 10 with a permanent low-field unit (AIRIS, Hitachi, Japan); the same technical parameters were used in all cases. Forty of 55 patients were examined at 1, 3, 6, 9 and 12 postoperative months, while 15 were followed-up longer (12 to 36 months postoperatively). At the first follow-up MR examination, 5 patients (2 ACL and 3 PCL) were excluded for incorrect tunnel position (1 case), hypertrophic scarring (2 cases) and new trauma (2 cases). MR findings were compared with clinical data of joint stability. RESULTS: MRI showed the different stages of the healing process in 20 ACL patients: proliferating soft tissue around the graft with the low signal intensity typical of tendons (stage I, 1-3 months postoperatively), the graft becomes progressively hyperintense (stage II, 3-9 months postoperatively), and finally the low signal intensity indicating completed ligamentization (stage III, 12 months postoperatively). As for PCL reconstructions, MR findings were similar but the process took longer, even 24 months. Finally, in the 15 cases of double reconstruction, both grafts were difficult to distinguish on T1-weighted images for a very long time (24-36 months postoperatively). DISCUSSION AND CONCLUSIONS: Relative to the ACL, ligamentization takes longer for PCL and combined ACL and PCL reconstructions, probably because the morphological changes in PCL and double grafts may be impaired by many factors, such as gravity, long bone tunnels, hemarthrosis, hyperplastic synovial reaction in the intercondylar notch; also, rehabilitation protocols differ in ACL from PCL patients. No signs of instability were found at physical or arthrometric examinations. MRI demonstrates the different stages of ligamentization and thus proves a useful tool for postoperative follow-up in cruciate ligament reconstructions. Contrast-enhanced (Gd) studies are reserved to the cases of graft impingement or if other abnormalities are suspected.     

Changing heat and moisture exchangers every 48 hours does not increase the incidence of nosocomial pneumonia.

This prospective study was conducted to evaluate the risk of nosocomial pneumonia when changing heat and moisture exchangers every 48 hours in 1996 instead of every 24 hours in 1995 for patients needing continuous mechanical ventilation. Medical and surgical patients in the two periods did not differ in terms of demographic characteristics and markers of acute or underlying illnesses. The incidence density of nosocomial pneumonia was not different in the two groups. Extended heat and moisture exchanger use reduces circuit manipulation and cost.     

Discoid medial meniscus: report of a case treated by arthroscopy

A complete discoid medial meniscus with a longitudinal tear was found in a 41-year-old man and treated by arthroscopy. The symptomatology was characterized by a sharp pain corresponding to the medial joint line, slight intrarticular effusion without locking or loss of motion. A review of the literature is described.     

Amacrine cells,bipolar cells and ganglion cells of the cat retina: A Golgi study

Neuronal types contributing to the inner plexiform layer of the cat retina are described based primarily on light microscopy of Golgi-impregnated retinal whole-mounts. Cells have been characterized on morphological criteria that include dendritic branching patterns, dendritic tree sizes, cell body sizes and stratification of processes in the inner plexiform layer. Nine different types of bipolar cell, 22 different types of amacrine cell and 23 different types of ganglion cell can be distinguished using one or more of these morphological criteria. The significance of the different morphological types of cells is discussed, particularly in relationship to the functional bisublamination of the cat inner plexiform layer.     

Two-step tumour targetting in ovarian cancer patients using biotinylated monoclonal antibodies and radioactive streptavidin

A new method for intraperitoneal tumour targetting in ovarian cancer using biotinylated monoclonal antibodies (MoAb) and radioactive streptavidin is described. Fifteen patients with histologically documented ovarian carcinoma were injected intraperitoneally with 2 mg of biotinylated MoAb MOv18, followed 3–5 days later by 100–150 g of indium-111 streptavidin, at the specific activity of 280–370 MBq/mg in 500 ml of normal saline. No toxicity was observed. Tumours were imaged from 2 to 48 h after radioactivity injection by recording both planar and single photon emission tomography (SPET) data. All patients underwent surgery 1–8 days later (mean 3 days) after scanning. The resected tumour and normal tissue radioactivity were measured. On the day of surgery, the tumour to normal tissue ratio was 9:1 (range 3:1–30:1) and 45:1 (range 12:1–120:1) for intra- and extraperitoneal samples, respectively. The mean tumor to blood ratio was 14:1 (range 4:1–30:1). The injected dose (i.d.) per gram of tumour was 0.112 (range 0.01–0.3) for recurrences and 0.05 for primary tumour (range 0.005–0.2). Over 24–48 h 14% i.d. (range 8–18% i.d.) was found in the urine, 14% i.d. (range 629% i.d.) in the blood and 63% i.d. (range 56–70% i.d.) was still in the peritoneal cavity. These preliminary clinical data suggest that this two-step strategy may be superior to the conventional approach (radiolabelled antibodies) for intraperitoneal radioimmunolocalization and radioimmunotherapy of ovarian cancer. Offprint requests to: G. Paganelli