Regulation of PACE propeptide-processing activity: requirement for a post-endoplasmic reticulum compartment and autoproteolytic activation.

PACE (paired basic amino acid cleaving enzyme) is a subtilisin-like serine protease involved in processing of propeptides in the constitutive secretory pathway. We here demonstrate that the transmembrane and cytoplasmic domains of PACE are required for retention in the secretory pathway but not for propeptide-cleaving activity. Addition of the endoplasmic reticulum retention signal Lys-Asp-Glu-Leu (KDEL) to the carboxyl terminus of the truncated molecule resulted in intracellular retention of the protein and loss of activity, indicating that the endoplasmic reticulum is an inappropriate environment for propeptide processing. In addition, mutation of a consensus PACE cleavage site within the amino-terminal region prevented processing of PACE to a mature form and destroyed activity. These data indicate that PACE is synthesized as a proprotein which requires autoproteolytic removal of an 81-residue pro sequence for optimal activity. A mutant form of PACE that lacked the pro sequence was nonfunctional, and addition of a pro sequence from a homologous subtilisin-like serine protease, PC2, did not restore activity. By analogy to the bacterial subtilisin family, the propeptide of PACE may guide the folding of PACE into an active enzyme.     

Self-testing for liver disease – response to an online liver test questionnaire

Abstract

Background: Elevated liver enzymes and chronic liver disease are associated with increased morbidity and mortality. Broad availability of internet questionnaires obtains representative insights into awareness of (chronic) liver disease in the general population. Also, these tools may be used to identify persons and populations at risk to prevent advanced liver disease.

Methods: An online questionnaire regarding awareness of liver disease, risk behavior and awareness of own liver tests was implemented online. During 43?months study period, 210,230 participants accessed the online questionnaire. Of these, 117,446 individuals completed the survey. All database access and input were registered and collected in a SQL based database for further evaluation.

Results: Awareness of own liver status was lower than expected. About 50.7% of all participants were uncertain about their liver enzyme status. In turn, risk behavior continues to be considerably high as 38.8% of participants stated high-risk behavior for alcohol consumption and 2.2% high-risk substance abuse such as cocaine or heroin. Our questionnaire was predominantly answered by participants under 65?years of age. Participants with high BMI may have been underrepresented.

Conclusion: Our study demonstrated the urgent need for improved liver screening, health education regarding risk behavior and improved awareness campaigns on liver disease. Interest of the general population may be presumed as more than 200,000 people accessed our test of their own accord.     

Accuracy of long head of the biceps tendon palpation by physical therapists; an ultrasonographic study

[Purpose] Examination and treatment of the long head of the biceps tendon (LHBT) requires accurate palpation. The purpose of this study was to determine physical therapists’ reliability and ability to accurately palpate the LHBT in two arm positions with ultrasound as the gold standard. [Participants and Methods] Examiners palpated the LHBT within the intertubercular groove (ITG) of the humerus on the bilateral shoulders of 32 asymptomatic (21 female; 24.3 ± 1.9 years) participants in 2 arm positions. The magnitude of distance between a marker and the border of the ITG was compared between 2 positions using an independent t-test. Percent accuracy was calculated. [Results] Inter-rater reliability was poor (position 1, k=1.04; position 2, k=0.016). Overall accuracy rate was 45.7% (117/256). Accuracy was 49.2% (63/128) and 42.2% (54/128) for testing position 1 and position 2 respectively. Mean distance palpated from the groove was M=2.58 mm (± 6.2 mm) for position 1 and M=3.77 mm (± 6.6 mm) for position 2. Inaccurate palpation occurred medially 72.3% (47/65) and 93.2% (69/74) in position 1 and position 2 respectively. [Conclusion] Results of this study did not support one arm position being more accurate over another for LHBT palpation.Key words: Palpation, Accuracy, Long head of biceps tendon     

A case of ameloblastic carcinoma with pulmonary metastases

A case initially thought to be ameloblastoma of the mandible which showed rapid local destruction and was demonstrated to have three pulmonary metastases post mortem 18 months after the first symptoms in the mandible. The diagnosis is now considered to be ameloblastic carcinoma. The difficulties in histological diagnosis and varying classifications of malignant odontogenic tumours is noted.     

Trunk muscle activity during the simultaneous performance of two motor tasks

A unique feature of trunk muscles is that they can be activated to meet functional requirements for combined behaviors, including those related to posture and breathing. Trunk muscles therefore may have developed mechanisms for dealing with simultaneous inputs for different task requirements. This study was designed to test the hypothesis that a linear addition in trunk muscle activities would occur when an isometric trunk task and a pulsed expiration task was performed simultaneously. Surface electromyograms (EMG) were recorded from four trunk regions (medial and lateral back, upper and lower lateral abdomen) in sitting during the performance of the individual isometric trunk task, the individual pressure task, and the combined task (isometric trunk and pressure task). The direction of static holding for the isometric trunk task was varied between flexion and extension positions. For the pressure task subjects produced two consecutive pressure pulses (2/s) to a target oral pressure. For each muscle recording, a linear prediction was calculated from the mathematical addition of the EMG recorded from the individual trunk and pressure tasks. This linear prediction was compared to the actual muscle activity recorded during the combined task. Typically the EMG from two muscles showed linear addition, such that the relative contribution of muscle activity did not change for the combined task. This suggests that the motor commands for each task reached these motor neuron pools essentially unmodified. The other two muscles showed nonlinear combination of two EMG patterns. That is, qualitatively both EMG patterns, specific to each command, were evident in the measured EMG traces for the combined task, but quantitatively the muscle did not meet all criteria for linear addition. Linear addition may provide a simple mechanism for combining breathing-related behaviors (expiratory efforts) with other trunk behaviors (holding against gravity). This suggests that some muscles can be shared for two different voluntary tasks without changing their contribution to either component task. At the same time, nonlinear combination suggests that some muscles are shared, but their contribution to either component task may be modulated, thus avoiding the construction of a third new and unique plan.     

19S IgM rheumatoid factor-7S IgG rheumatoid factor immune complexes isolated in sera of patients with juvenile rheumatoid arthritis

19S IgM rheumatoid factors (RF) and hidden 19S IgM RF have been associated with increased disease activity in juvenile rheumatoid arthritis (JRA). Recently, immune complexes (IC) were isolated from JRA sera by several methods which demonstrated the presence of 19S IgM RF. The present study evaluates 25 JRA patients' sera by separation on a Sepharose 4B column to which were bound F(ab')2 fragments of goat IgG antihuman IgM antibody to separate IgM-containing IC. The columns were sequentially eluted with 1 M ammonia and 0.1 M glycine-HCl buffer, pH 3.0. The isolated fractions were assayed for 19S IgM RF and 7S IgM RF by ELISA, IgG levels by immunodiffusion, and by preparative isoelectric focusing. The ammonia eluate from the alpha HIgM column revealed IgG, 19S IgM RF in six patients, and IgM RF in four patients. All were polyarticular-onset JRA patients. In the glycine-HCl eluate of sera, 19S IgM RF and IgG were also detected in 15 patients, all six seropositive, polyarticular-onset, six seronegative, polyarticular-onset, and three pauciarticular-onset patients. Significant 7S IgG RF titers were demonstrated in the glycine-HCl eluates of six patients, five seropositive, polyarticular-onset patients, and one seronegative, polyarticular-onset patient. Analysis by preparative isoelectric focusing of the IgM RF and IgG RF positive ammonia and glycine-HCl eluates showed IgM RF throughout the pH range (4-10), but the highest amount of IgM RF was in the pH range 4.0-5.5. Significant IgG RF titers were detected only in this restricted spectrotypic area of pH 4.0-5.5.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of optic disk blood flow in patients with open-angle glaucoma

PURPOSE: To characterize optic disk blood flow in patients with open-angle glaucoma compared with age-matched healthy control subjects. METHODS: In this prospective cross-sectional study, 90 eyes of 90 patients with open-angle glaucoma and 61 eyes of 61 age-matched healthy control subjects were evaluated. Flow in the optic disk cup and the neuroretinal rim were assessed with scanning laser Doppler flowmetry. Fundus pulsation amplitude in the cup and the macula were assessed with laser interferometry. Visual field mean deviation was measured with the Humphrey 30 to 2 program. RESULTS: Flow in the neuroretinal rim (-18%, P =.002), and in the cup (-46%, P <.001) and fundus pulsation amplitude in the cup (-33%, P <.001) and in the macula (-24%, P <.001) were significantly lower in patients with open-angle glaucoma compared with healthy control subjects. A significant association between blood flow measurements in the cup and fundus pulsation amplitudes in the cup was observed in both study cohorts. A significant association was also observed between the mean defect from visual field testing and ocular hemodynamic parameters. CONCLUSIONS: Reduced optic disk perfusion in patients with open-angle glaucoma is evidenced from two independent methods in the present study. Moreover, our data indicate that reduced ocular blood flow in these patients is linked to visual field changes. It remains to be established whether compromised optic disk and choroidal blood flow contributes to optic disk damage in glaucomatous eyes or is a secondary functional phenomenon.     

Effect of inhalation of different mixtures of O(2) and CO(2) on retinal blood flow

AIM: To determine the effects of various mixtures of O(2) and CO(2) on retinal blood flow in healthy subjects. METHODS: A randomised, double masked, four way crossover trial was carried out in 12 healthy male non-smoking subjects. Gas mixtures (100% O(2), 97.5% O(2) + 2.5% CO(2), 95% O(2) + 5% CO(2), and 92% O(2) + 8% CO(2)) were administered for 10 minutes each. Two non-invasive methods were used: laser Doppler velocimetry (LDV) for measurement of retinal blood velocity and fundus imaging with the Zeiss retinal vessel analyser (RVA) for the assessment of retinal vessel diameters. Arterial pH, pCO(2), and pO(2) were determined with an automatic blood gas analysis system. Retinal blood flow through a major temporal vein was calculated. RESULTS: Retinal blood velocity, retinal vessel diameter, and retinal blood flow decreased during all breathing periods (p <0.001 each). Administration of 92% O(2) + 8% CO(2) significantly increased SBP, MAP, and PR (p <0.001 each, versus baseline), whereas the other gas mixtures had little effect on systemic haemodynamics. Addition of 2.5%, 5%, and 8% CO(2) to oxygen caused a marked decrease in pH and an increase in pCO(2) (p <0.001 versus pure oxygen). CONCLUSIONS: Breathing of pure oxygen and oxygen in combination with carbon dioxide significantly decreases retinal blood flow. Based on these data the authors speculate that hyperoxia induced vasoconstriction is not due to changes in intravascular pH and cannot be counteracted by an intravascular increase in pCO(2).