Age-Related Alterations in Antioxidant Enzymes, Lipid Peroxide Levels, and Somatosensory-Evoked Potentials: Effect of Sulfur Dioxide

The effect of sulfur dioxide (SO₂) on somatosensory-evoked potentials (SEPs), thiobarbituric acid reactive substances (TBARS), and the activities of Cu,Zn-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were investigated in young (3 months), middle-age (12 months), and old (24 months) Swiss male albino rats. Ten ppm SO₂ was administrated to the animals of SO₂ groups in an exposure chamber for 1 h/day × 7 days/week × 6 while control groups were exposed to filtered air in the same condition. SO₂ exposure caused increased levels of brain Cu,Zn-SOD activity and decreased levels of brain GSH-Px activity in all experimental groups with respect to their corresponding control groups. Brain CAT activities were unaltered. Brain TBARS levels of all SO₂-exposed groups were significantly increased in comparison with their respective control groups. The mean latencies of P₁, P₂, and N₂ components in the older group were either significantly different from the young or from the middle-age groups. The mean latency of the N₁ component in the older group and that of P₁ and N₁ in the middle-age group were significantly increased compared with the young group. SO₂ exposure caused the prolongation of all components in the young group, whereas it affected only the P₂ component in the middle-age group, but it did not result in any latency change in the older group in comparison with their corresponding control groups. Received: 22 December 1998/Accepted: 7 April 1999     

Inhibition kinetics of human serum butyrylcholinesterase by Cd2+, Zn2+ and Al3+: comparison of the effects of metal ions on cholinesterases

Butyrylcholinesterase (BChE, EC 3.1.1.8) has been purified about 6600-fold from human serum with a procedure including ammonium sulfate fractionation (55-70%) with acid step at pH 4.5 and procainamide-Sepharose 4B affinity chromatography. The purified enzyme exhibited negative cooperativity with respect to butyrylthiocholine (BTCh) binding at pH 7.5. Ks was found to be 0.128 +/- 0.012 mM. Inhibition kinetics of the enzyme by Cd2+, Zn2+ and Al3+ were studied in detail. The 1/v vs 1/[BTCh] plots in the absence (control plot) and in the presence of different concentrations of cations intersected above 1/[BTCh]-axis. The data were analyzed by means of a nonlinear curve fitting program. The results demonstrated that all of the three cations are the linear mixed-type inhibitors of BChE. Ca2+ and Mg2+ had no effect on the enzyme activity in the experimental conditions. But when the enzyme was inhibited by 0.5 mM Cd2+ or Zn2+, Ca2+ and Mg2+ partially reactivated the inhibited allosteric form of BChE. Results were compared with data obtained from brain BChE purified from sheep.     

A study on impact and tensile strength of acrylic resin filled with short ultra-high molecular weight polyethylene fibers

In dentistry, acrylates have been used for preparing denture bases for 50 years. Although polymethylmethacrylates (PMMA) are known to be an ideal base material, they possess some undesirable mechanical properties, especially their impact strength and tensile strength, which appear to be unsatisfactory for some applications. Additives and fibers have therefore been used to enhance and improve these properties over the last two decades. The present article describes the mechanical properties, impact and tensile strength of PMMA reinforced with chopped ultra-high molecular weight polyethylene fiber (6 mm long). It was found that, although the processing involved for high loading of fibers into the PMMA was difficult, the resulting improvement of impact strength was substantial.     

Reversal of Cerebral Vasospasm by the Nitric Oxide Donor SNAP in an Experimental Model of Subarachnoid Haemorrhage

The constant release of nitric oxide (NO) is essential to maintain basal cerebrovascular tone. Oxyhaemoglobin, liberated by lysis of red blood cells after subarachnoid haemorrhage binds NO and prevents its entry into vascular smooth muscle cells. While endothelium-dependent vasoconstriction is preserved, decreased levels of NO inhibit endothelium-dependent relaxation and may cause vasospasm. S-nitrosothiols are potent vasodilators and precursors of NO. The authors' aim was to determine whether S-nitroso-N-acetylpenicillamine (SNAP), a stable S-nitrosothiol compound, could reverse vasospasm in an experimental vasospasm model in rabbit. Experimental subarachnoid haemorrhage (SAH) was induced in 37 New Zealand white rabbits. The animals were divided into four groups. Control (no SAH), SAH only, SAH plus saline and SAH plus SNAP. SNAP (15 micrograms/kg/min) or 0.09% saline (equal volume) was infused 46 hours after induction of SAH. All animals were killed by perfusion fixation 48 hours after SAH occurred. Basilar arteries were removed, sectioned and their cross sectional areas were evaluated in a blind manner, by light microscopy and by using computer assisted morphometry. Experimental SAH elicited vasospasm in all animals of SAH only and SAH plus saline group. In animals treated with SNAP, arterial narrowing was markedly attenuated without producing systemic hypotension. This widening achieved statistical significance when compared to the arteries of the SAH only and SAH plus saline group (p < 0.01). This study indicates that the NO donor SNAP is a potentially useful drug to reverse cerebral vasospasm due to SAH.     

Biliary–enteric fistulas: report of five cases and review of the literature

Internal biliary fistulas (IBF) are seen rarely. Because the symptoms and signs of IBF are not specific and the diagnosis is not suspected, these patients are commonly investigated with plain abdominal films (PAF), ultrasonography (US), upper gastrointestinal series (UGIS), barium enema (BE), and computed tomography (CT), but not always with endoscopic retrograde cholangiopancreatography (ERCP). The purposes of this article are (a) to attract attention of radiologists to presumptive findings of IBF, so as not to misdiagnose this unsuspected and rare disease, and (b) review of the literature while presenting radiologic features of our cases. Five cases of IBFs in which extrahepatic biliary tree communicating with duodenum (four cases) and colon (one case) are reported. Diagnostic work-up of cases were done by PAF, US, UGIS, BE, and CT. Aerobilia, which cannot be explained using other means, ectopic gallstone and small bowel dilatation, nonvisualization of the gallbladder despite no history of cholecystectomy, and thick-walled shrunken gallbladder adherent to neighboring organs were suggestive findings of IBF in our study. Knowledge of imaging findings suggestive of IBF and a high index of suspicion increase the diagnostic rate of IBFs. Received: 4 June 1998; Revision received: 28 July 1998; Accepted: 14 October 1998     

Vaginal atresia and Bardet-Biedl syndrome association: a component or a distinct entity?

Bardet-Biedl syndrome is an autosomal recessive disorder. It is characterized by cardinal anomalies including retinal dystrophy, digital malformations, mental retardation, obesity, and hypogonadism. Recently, renal anomalies also are mentioned among the cardinal signs. Although association of genital anomalies among affected boys are well known, the association of vaginal atresia and other structural genital anomalies are not mentioned among the less-common manifestations of Bardet-Biedl syndrome in girls. Two girls with Bardet-Biedl syndrome presented with hematometrocolpos in the preadolescent period and vaginal atresia was diagnosed. After surgical treatment and extended hospitalization, uncontrolled sepsis resulted in progressive renal failure and death of both patients. Vaginal atresia is often delayed or missed in the early childhood period. In girls with Bardet-Biedl syndrome, vaginal atresia or other structural genital anomalies should be evaluated more systematically during the initial diagnosis of the syndrome. In infancy, the evaluation of a child with vaginal atresia also should include the differential diagnosis of Bardet-Biedl syndrome. Vaginal atresia may either form a component of the syndrome, or girls who present with vaginal atresia in addition to other components of Bardet-Biedl syndrome might form a distinct entity.