Presence of tinnitus indicated by variable spontaneous otoacoustic emissions

Spontaneous otoacoustic emissions (SOAE) have been widely studied in normal subjects, and there is evidence of their high frequency stability in repeated recordings. A study to determine the frequency stability of SOAE in 53 of 100 consecutive patients, who presented with tinnitus and in whom SOAE were recordable, was undertaken. Patients were divided into five aetiologically homogeneous subgroups: (i) those with normal hearing and no identified pathology, (ii) those with sensorineural hearing loss of unknown origin, (iii) those with normal hearing, but complaining of tinnitus related to head injury, (iv) those with endolymphatic hydrops, and (v) those with noise exposure. The control group consisted of 20 subjects, selected on the basis of recordable SOAE from 38 volunteers with normal hearing and no tinnitus. The prevalence of SOAE and their inter-session frequency stability (reproducibility and relative frequency shift) were analysed. In contrast to the controls, the tinnitus group had significantly increased frequency variability of SOAE (lower reproducibility and increased relative frequency shift). The prevalence of subjects with SOAE was not notably different between the controls and subjects with tinnitus, if the tinnitus group was considered in toto, but a striking 100% prevalence of bilaterally present SOAE was observed in the tinnitus subgroup with head injury.     

Haloacetate-induced oxidative damage to DNA in the liver of male B6C3F1 mice

Brominated and chlorinated haloacetates (HAs) are by-products of drinking water disinfection. Dichloroacetate (DCA) and trichloroacetate (TCA) are hepatocarcinogenic in rodents, but the brominated analogs have received little study. Prior work has indicated that acute doses of the brominated derivatives are more potent inducers of oxidative stress and increase the 8-hydroxydeoxyguanosine (8-OH-dG) content of the nuclear DNA in the liver. Since, DCA and TCA are also known as weak peroxisome proliferators, the present study was intended to determine whether this activity might be exacerbated by peroxisomal proliferation. Classical responses to peroxisome proliferators, cyanide-insensitive acyl-CoA oxidase activity and increased 12-hydroxylation of lauric acid, were elevated in a dose-related manner in mice maintained on TCA and clofibric acid (positive control), but not with DCA, dibromoacetate (DBA) or bromochloroacetate (BCA). Administration of the HAs in drinking water to male B6C3F1 mice for periods from 3 to 10 weeks resulted in dose-related increases in 8-OH-dG in nuclear DNA of the liver with DBA and BCA, but not with TCA or DCA. These findings indicate that oxidative damage induced by the haloacetates is, at least in part, independent of peroxisome proliferation. In addition, these data suggest that oxidative damage to DNA may play a more important role in the chronic toxicology of brominated compared to the chlorinated haloacetates.     

Chemokine expression and leucocyte infiltration in Sj?gren''s syndrome

As the number of patients with anterior cruciate ligament reconstructions continues to grow, a subpopulation of patients with displaced tibia-fibula fractures will emerge who have had prior anterior cruciate ligament reconstructions. Previous cruciate ligament surgery can complicate the operative treatment of tibia-fibula fractures by intramedullary nailing. Technical complications arise because the tibial tunnel-graft-screw is in the path of insertion of the intramedullary implant. We present a case in which we traced the path of the patellar tendon autograft, adjusted our entry point for the tibial intramedullary canal, and removed the interference screw to facilitate the fracture surgery. This technical note provides an approach to planning intramedullary nailing of the tibia in patients with prior anterior cruciate ligament surgery.     

Genetic and other determinants of AMP deaminase activity in healthy adult skeletal muscle

AMPD1 genotype, relative fiber type composition, training status, and gender were evaluated as contributing factors to the reported variation in AMP deaminase enzyme activity in healthy skeletal muscle. Multifactorial correlative analyses demonstrate that AMPD1 genotype has the greatest effect on enzyme activity. An AMPD1 mutant allele frequency of 13.7 and a 1.7% incidence of enzyme deficiency was found across 175 healthy subjects. Homozygotes for the AMPD1 normal allele have high enzyme activities, and heterozygotes display intermediate activities. When examined according to genotype, other factors were found to affect variability as follows: AMP deaminase activity in homozygotes for the normal allele exhibits a negative correlation with the relative percentage of type I fibers and training status. Conversely, residual AMP deaminase activity in homozygotes for the mutant allele displays a positive correlation with the relative percentage of type I fibers. Opposing correlations in different homozygous AMPD1 genotypes are likely due to relative fiber-type differences in the expression of AMPD1 and AMPD3 isoforms. Gender also contributes to variation in total skeletal muscle AMP deaminase activity, with normal homozygous and heterozygous women showing only 85-88% of the levels observed in genotype-matched men.     

Influence of bulky side chains of amino acids on the solution conformation of peptide fragment (81-92) derivatives of CD4, TYICEVEDQKEE, as studied by NMR spectroscopy and molecular modeling

Solution conformation of CD4 fragment 81-92 TYICEVEDQKEE and two of its benzylated analogues was determined by two-dimensional 1H NMR spectroscopy, distance geometry and simulated annealing techniques. The structures of both benzylated derivatives are similar but are distinct from that of wild-type dodecapeptide. It is concluded from structural analysis that bulky side chain(s) of amino acid(s) at an appropriate position can have a marked effect on the conformation and thus the functions of a peptide.