Are biomarkers additive to pulmonary embolism severity index for severity assessment in normotensive patients with acute pulmonary embolism?

BACKGROUND: Biomarkers and clinical prediction rules have been proposed for severity assessment in acute pulmonary embolism (PE). AIM: The aim of this study was to compare biomarkers with the PE Severity Index (PESI), a validated scoring system for predicting 30-day mortality and to determine if addition of biomarkers to PESI would improve its predictive accuracy. STUDY DESIGN AND METHODS: We conducted a retrospective analysis of normotensive patients admitted with PE confirmed by CT pulmonary angiogram, to three teaching hospitals between January 2005 and July 2007. All patients had admission levels of D-dimer and Troponin I and calculation of PESI score on admission. The outcome of interest was 30-day mortality. RESULTS: There were 411 patients included in the study. Patients who died had higher levels of D-dimer (median 2947 ng/ml vs. 1464 ng/ml; P=0.02), Troponin (57.1% positive vs. 13.8%; P<0.0001) and higher PESI scores [median 109 vs. 83; P<0.0001], compared to survivors. PESI had superior accuracy for predicting 30-day mortality than a combination of Troponin and D-dimer (AUC 0.80 vs. 0.75). Addition of Troponin to PESI further improved the predictive value of the score (AUC 0.85 for vs. AUC 0.80 for PESI alone). CONCLUSION: Biomarkers and clinical prediction rules predict outcome in acute PE. Addition of troponin to the PESI scoring system improves the predictive value for 30-day mortality and may be useful for guiding initial management of patients presenting with PE.

Voluntary exercise alters GABA(A) receptor subunit and glutamic acid decarboxylase-67 gene expression in the rat forebrain.

Voluntary exercise improves stress coping and lowers anxiety. Because of the role of GABA in these processes, we investigated changes in the central GABAergic system in rats with free access to a running wheel for 4 weeks. The control animals had no access to a running wheel. Using insitu hybridisation histochemistry, we studied changes in gene expression of various GABA(A) receptor subunits as well as the GABA-synthesising enzyme glutamic acid decarboxylase-67 (GAD67) in the forebrain. There were region-specific decreases in alpha2, beta3 and gamma2 subunit mRNA expression and region-specific increases in beta1 subunit expression. The alpha5 and delta subunits, in the forebrain specifically associated with extrasynaptic GABA(A) receptors in the hippocampus, showed differential increases in expression levels. Expression of GAD67 mRNA was increased in many forebrain regions including all hippocampal cell layers, peri-paraventricular nucleus, bed nucleus stria terminalis, nucleus accumbens core and motor cortex, suggesting that long-term voluntary exercise enhances forebrain GABA synthesis capacity but in a region-specific manner. Thus, regular performance of exercise results in extensive changes in the forebrain GABAergic system that may be implicated in the changes in stress sensitivity and emotionality observed in exercising subjects.

Comparison between conventional interrupted high-resolution CT and volume multidetector CT acquisition in the assessment of bronchiectasis.

The aim of this study was to determine whether there is superior diagnostic accuracy for the detection and exclusion of bronchiectasis using 16-slice CT of the chest (1 mm) compared with conventional high-resolution CT (HRCT) of the chest (10 mm). A prospective study was carried out in patients who were referred for chest CT by a chest physician for the investigation of bronchiectasis over a 1-year period. All scans were performed using a 16-slice CT scanner. In addition to contiguous 1 mm slices, conventional HRCT images (1 mm slice every 10 mm) were prepared. Both datasets were dual read. There were 53 patients with a median age of 62 years (range, 51.5-71.5 years), comprising 14 males and 39 females. 10 of 53 scans had no bronchiectasis in either dataset. 36 patients had bronchiectasis diagnosed on both HRCT and 1 mm scans. Two patients had tubular bronchiectasis on the HRCT scans, which was not confirmed on the 1 mm scans. Five patients had confirmed tubular bronchiectasis on the 1 mm scans, which was not identified on HRCT scans. 40 extra lobes demonstrated bronchiectasis on the 1 mm vs the HRCT scans; of these, half were labelled as definite bronchiectasis on the 1 mm scan. There was a 32% increased confidence with the 1 mm scans compared with conventional HRCT of the chest in the diagnosis of bronchiectasis (p < 0.001). In conclusion, there is improved diagnostic accuracy and confidence for diagnosis and exclusion of bronchiectasis using 16-slice chest CT (1 mm cuts) compared with conventional HRCT of the chest.

Effects of the amino-terminal regions of tropomyosin and troponin T on thin filament assembly.

Bacterially expressed alpha-tropomyosin lacks the amino-terminal acetylation present in muscle tropomyosin and binds poorly to actin (Hitchcock-DeGregori, S. E., and Heald, R. W. (1987) J. Biol. Chem. 262, 9730-9735). Using a linear lattice model, we determined the affinity (Ko) of unacetylated tropomyosin or troponin-unacetylated tropomyosin for an isolated site on the actin filament and the fold increase in affinity (y) when binding is to an adjacent site. The absence of tropomyosin acetylation decreased Ko 2 orders of magnitude in the absence of troponin. Tropomyosin acetylation also enhanced troponin-tropomyosin binding to actin, not by increasing cooperativity (y), but rather by increasing Ko. These results suggest that the amino-terminal region of tropomyosin is a crucial actin binding site. Troponin promoted unacetylated tropomyosin binding to actin, increasing Ko more than 1,000-fold. Troponin70-259, which lacks the troponin T peptide (1-69) spanning the overlap between adjacent tropomyosins, behaved similarly to intact troponin. Cooperative interactions between adjacent troponin-tropomyosin complexes remained strong despite the use of a nonpolymerizable tropomyosin and a troponin unable to bridge neighboring tropomyosins physically. The Ko for troponin70-259-unacetylated tropomyosin was 500-fold greater than for troponin159-259-unacetylated tropomyosin, indicating that troponin T residues 70-158 are critical for anchoring troponin-tropomyosin to F-actin. The mechanism of cooperative thin filament assembly is discussed.

Analysis of troponin-tropomyosin binding to actin. Troponin does not promote interactions between tropomyosin molecules.

The binding of tropomyosin to actin and troponin-tropomyosin to actin was analyzed according to a linear lattice model which quantifies two parameters: Ko, the affinity of the ligand for an isolated site on the actin filament, and gamma, the fold increase in affinity when binding is contiguous to an occupied site (cooperativity). Tropomyosin-actin binding is very cooperative (gamma = 90-137). Troponin strengthens tropomyosin-actin binding greatly but, surprisingly, does so solely by an 80-130-fold increase in Ko, while cooperativity actually decreases. Additionally, troponin complexes containing TnT subunits with deletions of either amino acids 1-69 (troponin70-259) or 1-158 (troponin159-259) were examined. Deletion of amino acids 1-69 had only small effects on Ko and y, despite this peptide's location spanning the joint between adjacent tropomyosins. Ca2+ reduced Ko by half for both troponin and troponin70-159 and had no detectable effect on cooperativity. Troponin159-259 had much weaker effects on tropomyosin-actin binding than did troponin70-259 and had no effect at all in the presence of Ca2+. This suggests the importance of Ca(2+)-insensitive interactions between tropomyosin and troponin T residues 70-159. Cooperativity was slightly lower for troponin159-259 than tropomyosin alone, suggesting that the globular head region of troponin affects tropomyosin-tropomyosin interactions along the thin filament.

Mutagenicity evaluation of HC Blue No. 1 and HC Blue No. 2, II. Effect on the in vitro induction of unscheduled DNA synthesis in rat, mouse, rabbit, hamster, and monkey primary hepatocytes.

2 hair dyes, HC Blue No. 1 and HC Blue No. 2, were evaluated for the in vitro induction of unscheduled DNA synthesis (UDS) in primary hepatocytes of rat, mouse, hamster, rabbit and monkey. NC Blue No. 1, which is identified as a carcinogen by the National Toxicology Program, induced UDS in all 5 systems. HC Blue No. 2, which is identified as a non-carcinogen, induced UDS in rat, mouse, hamster and rabbit primary hepatocytes. 3-Methylcholanthrene and methyl methanesulfonate were used as positive controls to determine the sensitivity of the test system.

Quantification of unscheduled DNA synthesis by a whole cell counting method.

A procedure was developed for the quantification of the autoradiographic assay for unscheduled DNA synthesis. Relative to commonly used practices for grain counting, this procedure provides a more accurate net nuclear grain count by eliminating the subjectivity currently associated with selection of the areas to be counted for the cytoplasmic background count. Briefly, the object area and aperture area modes of an ARTEK 880 colony counter are used to collect values for the total number of silver grains over a particular cell (nuclear and cytoplasmic counts), as well as for the nuclear and cytoplasmic areas. These values are then employed in a short algorithm to determine the net nuclear grain count. This new method provides greater sensitivity for defining weak UDS responses and the data collected readily lends itself to statistical analysis.

Second-trimester maternal serum alpha-fetoprotein levels in pregnancies associated with gastroschisis and omphalocele.

This population-based study analyzes maternal serum alpha-fetoprotein (MSAFP) distributions for 20 cases of gastroschisis and 13 cases of omphalocele occurring in singleton pregnancies from among 72,782 second-trimester pregnancies in Maine and Rhode Island screened consecutively between January 1, 1979 and February 28, 1987. Median values (and ranges) for the two lesions were 4.1 multiples of the median (0.5-29.8) for omphalocele and 7.0 multiples of the median (3.6-13.5) for gastroschisis. The MSAFP distributions for the two conditions were both log-Gaussian, and the log standard deviation was smaller for gastroschisis than for omphalocele. The MSAFP screening sensitivity was greater for gastroschisis than for omphalocele at any given cutoff, and the overall sensitivity of this screening process for detecting open ventral wall defects will differ, therefore, depending upon the relative proportion of gastroschisis and omphalocele cases that occur in the screened population.

Very low versus undetectable maternal serum alpha-fetoprotein values and fetal death.

Very low maternal serum alpha-fetoprotein (MSAFP) levels (less than 10 ng/mL) are known to be associated with non-viable pregnancies, including conditions such as fetal death, molar pregnancies, and non-pregnancies. There has not been agreement, however, as to whether very low MSAFP levels indicate already existing fetal deaths or are actually predictive. We analysed 230 pregnancies with MSAFP levels less than 10 ng/mL from among 15,807 women (1.5 per cent) screened consecutively during a three-year period and identified 26 non-viable pregnancies, 22 of which were diagnosed sonographically as part of the screening process (17 missed abortions, 3 blighted ova, 2 non-pregnancies). Furthermore, 20 of these 22 pregnancies were associated with essentially undetectable MSAFP levels (less than 5 ng/mL). Our data indicate that pregnancies with MSAFP values less than 5 ng/mL are the group most strongly associated with fetal non-viability and that very low MSAFP values are not strongly predictive for fetal death.

Influence of age, sex and strain on the in vitro induction of unscheduled DNA synthesis in rat hepatocyte primary cultures.

The activity of chemical-induced unscheduled DNA synthesis was evaluated in hepatocyte primary cultures from Fischer 344 and Sprague-Dawley rats over a period of two years. In this two-year study hepatocytes from both sexes and strains were prepared from animals 2, 8, 14, 20 and 25 months of age and UDS was measured by autoradiography following treatment with N-methyl-N'-nitro-N-nitrosoguanidine and 2-acetylaminofluorine. A dose-related positive response occurred for both compounds throughout the study in hepatocytes from male and female Fischer rats and male Sprague-Dawley rats. The magnitude of the response was greatest in hepatocytes from male Fischer rats and a markedly lower response in unscheduled DNA synthesis occurred in all cultures prepared from animals of both strains and sexes at 20 and 25 months of age. Hepatocytes from female Sprague-Dawley rats showed a low level of unscheduled DNA synthesis with N-methyl-N'-nitro-N-nitrosoguanidine throughout the study. The most striking finding was the absence of a UDS response to 2-acetylaminofluorene by hepatocytes from Sprague-Dawley females at the 8, 14, 20 or 25 month periods. The results indicate an age-related decrease in chemical-induced unscheduled DNA synthesis activity among rats.

Evaluation of ochratoxin A for mutagenicity in a battery of bacterial and mammalian cell assays.

Ochratoxin A (OA), a nephrotoxic mycotoxin, was evaluated for genotoxic potential in a battery of in vitro and in vivo assays. OA was not mutagenic to Salmonella typhimurium, either with or without metabolic activation, in the plate incorporation (Ames) test at concentrations of 50-600 micrograms OA/plate or in the gradient plate assay at concentrations of 0.1-1000 micrograms OA/ml. No induction of unscheduled DNA synthesis was evident in primary cultures of rat hepatocytes exposed to concentrations of OA ranging from 0.000025 to 500 micrograms/ml. In the mouse lymphoma forward mutation assay, exposure of L5178Y TK+/- mouse lymphoma cells to OA did not increase the numbers of L5178Y TK-/- mutants. There was no significant difference between the numbers of sister-chromatid exchanges in cells from OA-treated Chinese hamsters and those in cells from the negative-control animals.

Predictive nomograms for forced expiratory volume, forced vital capacity, and peak expiratory flow rate, in Chinese adults and children.

A survey of three indices of ventilatory capacity, forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR), was undertaken on 3490 Chinese inhabitants of Hong Kong. Nomograms have been constructed for the prediction of these three indices for subjects between the ages of 5 and 75 years.

The induction of bacterial mutation and hepatocyte unscheduled DNA synthesis by monosubstituted anilines.

A group of 45 monosubstituted aniline compounds was tested for the induction of point mutations in Salmonella typhimurium and Escherichia coli as well as for unscheduled DNA synthesis (UDS) in rat hepatocyte culture. Eleven compounds were bacterial mutagens, and five compounds induced UDS. Among these a correspondence between mutagenicity and UDS occurred for only two compounds (o-phenylenediamine and 4-aminobiphenyl), and these were also reported to be carcinogenic in rodents. Bacterial mutation was observed for one compound (p-phenylenediamine) not carcinogenic in rodents, and six suspect carcinogens were not detected in either test. In addition, eight compounds of unknown carcinogenic potential induced either bacterial mutation or UDS.

A survey of ventilatory capacity in Chinese subjects in Hong Kong.

A survey of three indices of ventilatory capacity (forced expiratory volume in one second, FEV1; forced vital capacity, FVC; and peak expiratory flow rate, PEFR) was carried out on 3490 Chinese inhabitants of Hong Kong aged between 5 and 97 years. The results are compared with those of previous surveys of ventilatory capacity in a variety of ethnic groups. Our results confirm previous findings that the indices FEV1 and FVC are proportional to the square of the height of the subject, but we have found that PEFR is proportional to height itself. Using the indices FEV1/height2, and PEFR/height we have derived regression equations which may be used to predict normal values of the ventilatory indices for both adults and children. An interesting observation in this cross-sectional survey was that although all ventilatory indices were adversely affected by smoking, the rates of decline of these indices with age were not accelerated in smokers compared with non-smokers, in contrast to the findings of previous surveys on European populations.

A survey of deaths in Hong Kong attributed to tuberculosis.

Records obtained for 578 (96%) of the 602 patients certified as having died from tuberculosis in Hong Kong during a 1-year period were reviewed by an expert independent assessor in London, In his opinion 14 (2% of the 578) had never had tuberculosis, and in 28 (5%) it was not possible to decide whether or not the patient had ever had tuberculosis. Tuberculosis had been no more than a contributory factor in causing death in 44 (8%), in 29 (5%) it was irrelevant, and in 33 (6%) it was not possible to determine what role it had played. The remaining 430 (74%) patients were considered actually to have died from tuberculosis, 307 from active disease and 123 from the late effects of inactive disease. If all 578 patients had died from tuberculosis this would represent a death rate for the survey year of 13.1 per 100 000 of the population. The rate falls to 9.7 per 100 000 if based on the 430 patients considered by the assessor to have died from tuberculosis, a reduction of 26%. Since the annual death rate from active disease (6.9 per 100 000 in this survey) is a better index of the current efficiency of an antituberculosis programme than the total death rate, it is suggested that efforts should be made to obtain and publish separate annual rates for deaths from active and from inactive tuberculosis. An analysis of potentially avoidable delays and failures in diagnosis showed that these were mainly due to the patient's delay in seeking or accepting advice, or inadequate investigation, particularly failure to examine the sputum, by the unofficial (non-governmental) medical services. The majority of failures in management were attributable in whole or in part to the patient.

Chemically-induced unscheduled DNA synthesis in primary rat hepatocyte cultures: a comparison with bacterial mutagenicity using 218 compounds.

The autoradiographic identification of unscheduled DNA synthesis (UDS) in primary cultures of adult rat hepatocytes (HPC) has been proposed as a predictive test for mutagens/carcinogens. To assess the predictive value of this test, results in the hepatocyte UDS assay were compared with data for bacterial mutagenicity using a modified Ames test. Over 200 compounds representing a variety of chemical classes consisting of procarcinogens, ultimate carcinogens, and noncarcinogens were tested in each system. The accurate discrimination of many carcinogens/noncarcinogens was demonstrated by both systems. The induction of UDS in hepatocytes showed an excellent correlation with bacterial mutagenesis in response to polycyclic aromatic hydrocarbons, aromatic amines, biphenyls, nitrosamines, carbamates, azo-compounds, acridines, halogenated compounds, nitrosureas, quinolines, pyridines, purines, pyrimidines, esters and carbamates. Nitrocompounds, although active in bacteria, were poor inducers of UDS. The results support the complementary and confirmatory nature of these tests for genotoxic chemicals and indicate the usefulness of the hepatocyte UDS system as a component in a battery of short-term predictive tests for mutagens/carcinogens.

Comparison of three in vitro assays for carcinogen-induced DNA damage.

DNA damage induced by five ultimate carcinogens and five procarcinogens was evaluated by three methods: (1) DNA strand breaks in Crandall feline kidney (CRFK) cells measured by alkaline sucrose gradient centrifugation; (2) unscheduled DNA synthesis (UDS) in CRFK, Syrian hamster embryo (SHE), and rat hepatocyte cultures measured by liquid scintillation counting; and (3) UDS in CRFK, SHE, and rat hepatocyte cultures measured by autoradiography. DNA strand breaks were observed with three procarcinogens and four ultimate carcinogens. Only two procarcinogens and two ultimate carcinogens could be identified by liquid scintillation counting. A positive autoradiographic response for UDS was observed in CRFK cells with four of five ultimate carcinogens and one procarcinogen. SHE cells showed a positive autoradiographic response for UDS with all ultimate carcinogens and three procarcinogens. The autoradiographic system with primary rat hepatocyte cultures was the only one in which a positive response for DNA damage was elicited for all 10 carcinogens.