Abstracts

Dental enamel is the most mineralized tissue of vertebrate organisms. Enamel biosynthesis is initiated by the secretion, processing, and self-assembly of a complex mixture of proteins. The formation of an ordered enamel organic extracellular matrix (ECM) seems be a crucial step for the proper formation of mineral phase. Polarizing microscopy demonstrates that the ordered supramolecular structure of the secretory-stage enamel organic ECM is strongly birefringent. In the present work we analyzed the birefringence of secretory-stage enamel organic ECM in amelogenin (Amelx)- and enamelysin (Mmp20)-deficient mice. Female Amelx^+/? animals showed significant reduction in optical retardation values when compared with the Amelx^+/+ subgroup (p = 0.0029). The secretory-stage enamel organic ECM of the Amelx^?/? subgroup did not exhibit birefringence. The secretory-stage enamel organic ECM of Mmp20^?/? mice showed a significant decrease in optical retardation as compared with Mmp20^+/+ and Mmp20^+/? mice (p = 0.0000). Mmp20^+/? and Mmp20^+/+ mice exhibited similar birefringence (p = 1.0000). The results presented here support growing evidence for the idea that the birefringence of secretory-stage enamel organic ECM is influenced by the ordered supramolecular organization of its components.     

The management and long term outcome of organic acidaemias

We review the outcome of patients with maple syrup urine disease (14 classical patients and three variants), biotinidase deficiency (two patients) and non-cofactor-responsive variants of methylmalonic acidaemia (eight patients), propionic acidaemia (eight patients) and isolated 3-methylcrotonyl CoA carboxylase deficiency (three patients). Their survival, growth, intellectual development and other clinical problems are analysed. With the exception of isolated 3-methylcrotonyl CoA carboxylase deficiency the outcome of patients with disorders that are not cofactor responsive is disappointing. Twelve patients have died (five maple syrup urine disease, two methylmalonic acidaemia, five propionic acidaemia) and many of the survivors are developmentally retarded. The outlook is worst for patients with propionic acidaemia presenting in the neonatal period but a good outcome is possible for patients with maple syrup urine disease if the diagnosis is made early.     

Brucellosis among Hospitalized Febrile Patients in Northern Tanzania

Acute and convalescent serum samples were collected from febrile inpatients identified at two hospitals in Moshi, Tanzania. Confirmed brucellosis was defined as a positive blood culture or a ≥ 4-fold increase in microagglutination test titer, and probable brucellosis was defined as a single reciprocal titer ≥ 160. Among 870 participants enrolled in the study, 455 (52.3%) had paired sera available. Of these, 16 (3.5%) met criteria for confirmed brucellosis. Of 830 participants with ≥ 1 serum sample, 4 (0.5%) met criteria for probable brucellosis. Brucellosis was associated with increased median age (P = 0.024), leukopenia (odds ratio [OR] 7.8, P = 0.005), thrombocytopenia (OR 3.9, P = 0.018), and evidence of other zoonoses (OR 3.2, P = 0.026). Brucellosis was never diagnosed clinically, and although all participants with brucellosis received antibacterials or antimalarials in the hospital, no participant received standard brucellosis treatment. Brucellosis is an underdiagnosed and untreated cause of febrile disease among hospitalized adult and pediatric patients in northern Tanzania.     

A new EEG biomarker of neurobehavioural impairment and sleepiness in sleep apnea patients and controls during extended wakefulness

ObjectiveTo explore the use of detrended fluctuation analysis (DFA) scaling exponent of the awake electroencephalogram (EEG) as a new alternative biomarker of neurobehavioural impairment and sleepiness in obstructive sleep apnea (OSA).MethodsEight patients with moderate–severe OSA and nine non-OSA controls underwent a 40-h extended wakefulness challenge with resting awake EEG, neurobehavioural performance (driving simulator and psychomotor vigilance task) and subjective sleepiness recorded every 2-h. The DFA scaling exponent and power spectra of the EEG were calculated at each time point and their correlation with sleepiness and performance were quantified.ResultsDFA scaling exponent and power spectra biomarkers significantly correlated with simultaneously tested performance and self-rated sleepiness across the testing period in OSA patients and controls. Baseline (8am) DFA scaling exponent but not power spectra were markers of impaired simulated driving after 24-h extended wakefulness in OSA (r = 0.738, p = 0.037). OSA patients had a higher scaling exponent and delta power during wakefulness than controls.ConclusionsThe DFA scaling exponent of the awake EEG performed as well as conventional power spectra as a marker of impaired performance and sleepiness resulting from sleep loss.SignificanceDFA may potentially identify patients at risk of neurobehavioural impairment and assess treatment effectiveness.