Tissue engineering of stratified articular cartilage from chondrocyte subpopulations

OBJECTIVE: To test if subpopulations of chondrocytes from different cartilage zones could be used to engineer cartilage constructs with features of normal stratification. ESIGN: Chondrocytes from the superficial and middle zones of immature bovine cartilage were cultured in alginate, released, and seeded either separately or sequentially to form cartilage constructs. Constructs were cultured for 1 or 2 weeks and were assessed for growth, compressive properties, and deposition, and localization of matrix molecules and superficial zone protein (SZP). RESULTS: The cartilaginous constructs formed from superficial zone chondrocytes exhibited less matrix growth and lower compressive properties than constructs from middle zone chondrocytes, with the stratified superficial-middle constructs exhibiting intermediate properties. Expression of SZP was highest at the construct surfaces, with the localization of SZP in superficial-middle constructs being concentrated at the superficial surface. CONCLUSIONS: Manipulation of subpopulations of chondrocytes can be useful in engineering cartilage tissue with a biomimetic approach, and in fabricating constructs that exhibit stratified features of normal articular cartilage.     

Amniotic membrane, tear film, corneal, and aqueous levels of ofloxacin in rabbit eyes after amniotic membrane transplantation

PURPOSE: We evaluated ocular penetration and drug levels in tears after topical ofloxacin instillation in rabbit eyes with amniotic membrane transplantation (AMT). METHODS: Forty-eight New Zealand White rabbits were used. In the first set of experiments, 24 rabbits (24 eyes) were divided into four groups according to the epithelial removal or AMT. Topical ofloxacin was instilled four times every 15 minutes. One hour after the last eyedrop, the concentration of ofloxacin in the amniotic membrane, cornea, and aqueous humor was evaluated. In the second set of experiments, 24 rabbits were divided into six groups according to AMT (transplantation of lyophilized or fresh amniotic membrane) or duration of application. Ofloxacin ointment or two drops of ofloxacin were applied to the right eye, and then tear samples were collected after 0.5, 1, 2, 4, and 6 hours for the analysis of ofloxacin concentration. RESULTS: Mean ofloxacin concentrations in the cornea and aqueous humor were statistically higher in deepithelialized cornea regardless of AMT (p < 0.05). The mean tear levels of ofloxacin in the AMT groups were statistically higher than those in non-AMT groups (p < 0.05). There was no statistical significance in the tear level of ofloxacin between lyophilized amniotic membrane groups and fresh amniotic membrane groups nor between 1-hour amniotic membrane-attached groups and 6-hour amniotic membrane-attached groups. CONCLUSION: Amniotic membrane transplantation seems to interfere with the ocular penetration of topical ofloxacin in normal rabbit corneas but enhances ofloxacin penetration in corneas with epithelial defects. The ofloxacin level in tears was higher in eyes with AMT up to 1 hour after topical ofloxacin use. Therefore, it seems that amniotic membrane has some potential to act as an effective drug delivery system.     

Congenital infantile fibrosarcoma of the upper extremity

Congenital-infantile fibrosarcoma is an unusual childhood tumor that occurs mainly in children under 5 years of age. More than 300 cases have been reported in the literature so far, very few of them at birth. A distinction must be made between it and its adult counterpart because of differences in their clinical behaviour. We report here a case of congenital fibrosarcoma in a 4-day-old female infant.     

Excretory urography with iohexol: evaluation in children

A multicenter clinical study was conducted using iohexol, a second-generation nonionic contrast medium, for excretory urography performed in 130 children. Doses of iohexol (300 mg iodine/ml) ranged between 150 and 660 mgI/kg (0.5 and 2.2 ml/kg). Iohexol was tolerated well, and no significant adverse reactions occurred. Sixty-five iohexol urograms were evaluated to determine the minimum dose for adequate visualization of the kidneys and collecting systems. A dose greater than 300 mgI/kg (1.0 ml/kg) always resulted in a urogram of diagnostic quality, while visualization was insufficient for diagnosis in 10% of studies done with doses of 150-300 mgI/kg (0.5-1.0 ml/kg). Another 65 iohexol urograms were compared in a blinded manner with a similar number of studies performed using iothalamate meglumine at comparable iodine concentration and dose. Visualization of calyces and pelvoinfundibular structures achieved with iohexol was rated better with statistical significance, but there was no difference in visualization of the renal parenchyma or ureters. Use of iohexol in excretory urography may be advantageous in children who are at greatest risk for an adverse reaction to contrast media or in those most likely to benefit from use of a low osmolality contrast agent.     

Neurotransmitter modulation of calcium current in rat spinal cord neurons

The modulation of Ca2+ currents by neurotransmitters was studied in freshly dissociated rat spinal cord neurons, using the whole-cell patch-clamp technique. GABA, baclofen, adenosine, ATP, serotonin, norepinephrine, somatostatin, and dynorphin A inhibited the current through Ca2+ channels in a substantial fraction of cells, while substance P, vasoactive intestinal polypeptide, [D-ala2,d-leu5]-enkephalin, cholecystokinin-8 (sulfated), calcitonin gene-related peptide, angiotensin II, neurotensin, vasopressin, and thyrotropin-releasing hormone had no effect. In the case of baclofen, the inhibition is mediated, at least in part, by a GTP-binding protein. Suppression of Ca2+ current by neurotransmitters may represent a mechanism of presynaptic inhibition in the spinal cord.