Effects of melanotan II,a melanocortin agonist,on grooming and exploration in rats after repeated restraint/immobilization

2 mg/kg melanotan II (MTII, administered i.p.), a cyclic peptide analog of α-melanocyte stimulating hormone, at a single dose increased grooming in naive rats placed in an unfamiliar open-field device without changing locomotion or rearing. Male rats exposed to restraint/immobilization stress (IS) for 1 h on three consecutive days displayed increased grooming after the second stressor exposure, compared to pre-stress levels. MTII, administered to the rats after IS, enhanced the grooming response compared both to the pre- and post-stress values. The increase was greatest after the first dose and declined over the following two applications. As to the locomotion of rats in the entire experimental space, IS reduced the distance moved only after the first two stressor exposures; MTII did not influence these alterations. Locomotion in the central part of arena was not reduced by the stressor or by MTII, on the contrary, there was an increase in both groups after the third intervention. The only observed change in rearing was an increase in the MTII group after the third restraint exposure. Thus, MTII selectively increased grooming without markedly affecting the spatio-temporal structure of locomotor behavior in the open-field. The decline of MTII enhanced grooming over the three test days may be interpreted in terms of adaptation to the stressor and of the developing tolerance to the peptide.     

Recurrent posterior dislocation following primary posterior-stabilized total knee arthroplasty

In our series of 136 patients with primary total knee arthroplasty using posterior-stabilized prosthesis, a female patient with Parkinson disease developed posterior dislocation of the knee 9 months after surgery. Eventually, the dislocation became recurrent, occurring several times a day. The patient made the reposition always by herself. Two months after the first dislocation, we performed the revision of the polyethylene tibial insert and found wearing of the tibial insert's cam as an hitherto unreported cause of the mechanical instability of the total knee prosthesis.     

Lid retraction etiology

The upper lid position is abnormal if it exposes a white band of sclera between the lid margin and the upper corneal limbus while the retracted lower lid lies below the inferior corneal margin and is tethered to the orbital margin. Lid retraction is a sign of many congenital and acquired diseases and is characterised by multifactorial etiology. The aim of this study was to discuss the etiology of lid retraction divided into four categories: neurogenic, myogenic, mechanical and miscellaneous, what suggests a successful differential diagnostic and therapeutic approach.     

Dilemmas about the antenatal use of corticosteroids for prevention of neonatal morbidity and mortality

Neonatal respiratory distress syndrome (RDS) is one of the biggest problems in modern obstetrics. The incidence of RDS is 1%-2%. RDS is a condition of insufficient surfactant production. Surfactant is a complex molecule which is responsible for maturation of fetal lungs. The most important factor for insufficient surfactant production and pulmonary immaturity is shortening of gestation, i.e. preterm delivery. Antenatal corticosteroids for maturation of fetal lungs are in use for over thirty years. Corticosteroids decrease the incidence and intensity of RDS, the severity of intracerebral hemorrhage, and overall neonatal morbidity and mortality. The mechanism of corticosteroid action is probably induction of fetal pulmonary enzyme complex that is responsible for adequate surfactant production and regulation of pulmonary interstitial fluids. In this literature review, we analyze long- and short-term benefits and risks of single and multiple antenatal corticosteroid administration.