Random forest can predict 30-day mortality of spontaneous intracerebral hemorrhage with remarkable discrimination.

BACKGROUND AND PURPOSE: Risk-stratification models based on patient and disease characteristics are useful for aiding clinical decisions and for comparing the quality of care between different physicians or hospitals. In addition, prediction of mortality is beneficial for optimizing resource utilization. We evaluated the accuracy and discriminating power of the random forest (RF) to predict 30-day mortality of spontaneous intracerebral hemorrhage (SICH). METHODS: We retrospectively studied 423 patients admitted to the Taichung Veterans General Hospital who were diagnosed with spontaneous SICH within 24 h of stroke onset. The initial evaluation data of the patients were used to train the RF model. Areas under the receiver operating characteristic curves (AUC) were used to quantify the predictive performance. The performance of the RF model was compared to that of an artificial neural network (ANN), support vector machine (SVM), logistic regression model, and the ICH score. RESULTS: The RF had an overall accuracy of 78.5% for predicting the mortality of patients with SICH. The sensitivity was 79.0%, and the specificity was 78.4%. The AUCs were as follows: RF, 0.87 (0.84-0.90); ANN, 0.81 (0.77-0.85); SVM, 0.79 (0.75-0.83); logistic regression, 0.78 (0.74-0.82); and ICH score, 0.72 (0.68-0.76). The discriminatory power of RF was superior to that of the other prediction models. CONCLUSIONS: The RF provided the best predictive performance amongst all of the tested models. We believe that the RF is a suitable tool for clinicians to use in predicting the 30-day mortality of patients after SICH.

Intrathyroidal activated (Ia+) T-lymphocyte CD+ subsets and B cells in Graves' hyperthyroidism respond rapidly to propylthiouracil therapy: demonstration using fine needle aspirates and two-colour laser flow cytometry.

Using a rapid (whole blood lysis) single laser microfluorocytometric technique that permitted the simultaneous analysis of two monoclonal antibody surface markers tagged with different fluorescent dyes, the intrathyroidal (IT) and peripheral blood (PB) activated [Ia+ = DR+] T-lymphocyte CD3+ subsets and [F(ab')2+] B cells were studied in hyperthyroid patients with Graves' disease (GD) before and after 1-4 months of propylthiouracil (PTU) therapy. IT lymphocytes were obtained by serial fine needle aspiration. In untreated patients a marked quantitative (approximately < 10 fold) increase in activated (Ia+ CD3+) T-lymphocytes as well as CD4+ and CD8+ subsets, for IT compared to PB sites, was found. The percentages of Ia+ CD4+ and Ia+ CD8+ within Ia+ CD3+ were not significantly different between the two sources of T cells. F(ab')2+. B cells were significantly increased (approximately 2-3 fold) in IT compared to PB. In hyperthyroid GD patients, PTU therapy induced rapid and specific changes within the Ia+ CD3+ subsets, namely a reduction in the Ia+ CD4+ subset and an increase in the Ia+ CD8+ subset, resulting in a marked decrease in the Ia+ CD4+/Ia+ CD8+ ratio. These changes occurred in association with a reduction in serum T4 and T3 concentration. No significant changes could be detected within the total (predominantly non-activated) CD3+, CD4+ or CD8+ lymphocyte subsets within PB and only a small decrease in the CD4+/CD8+ ratio was demonstrated in IT, following PTU treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of a crystallization pathway for Z-DNA hexanucleotides.

Crystallization of macromolecules for structural studies has long been a hit-or-miss process. The crystallization of hexanucleotides as Z-DNA was studied, and it was shown that the cation concentration for crystal formation could be predicted from solvation free energy (SFE) calculations. Solution studies on the conformation and solubilities of the hexanucleotides showed that a critical concentration of the DNA in the Z-conformation must be present in solution to effect crystallization. The SFE calculations therefore predict the propensity of the hexanucleotides to adopt the left-handed conformation and the driving force required to reach this critical concentration relative to the intrinsic solubility of Z-DNA for crystallization.

Concurrent aortic and mitral valve echocardiography permits measurement of systolic time intervals as an index of peripheral tissue thyroid functional status.

Systolic time intervals (STI) were measured directly from concurrent aortic and mitral valve echocardiographic tracings in 127 subjects to assess their utility as an index of peripheral tissue thyroid functional status. The subjects were categorized according to clinical symptoms and the results of thyroid function tests into the following 7 study groups: normal subjects (n = 34), overt hyperthyroid subgroup I (n = 12), overt hyperthyroid subgroup II (n = 28), subclinical hyperthyroid (n = 15), subclinical hypothyroid (n = 22), overt hypothyroid subgroup II (n = 6), and overt hypothyroidism subgroup I (n = 10). Compared with normal subjects, overt hyperthyroid subgroup I patients had a significantly shortened mean isovolumetric contraction time (ICT), preejection period (PEP), and PEP/LVET (LVET = left ventricular ejection time; P less than or equal to 0.0005); the overt hypothyroid subgroup I patients also had significantly lengthened mean ICT (P less than or equal to 0.005), PEP, and PEP/LVET (P less than or equal to 0.0005). Compared with normal subjects, overt hyperthyroidism subgroup II patients also had a very significant shortening of ICT (P less than 0.0005) as well as a significantly shortened PEP and PEP/LVET (P less than or equal to 0.005), whereas subclinical hyperthyroid patients (with normal serum free T4 index and total T3, and suppressed TSH by immunoradiometric assay) also had ICT, PEP, and PEP/LVET STI values which were significantly shortened (P less than 0.05) values. Compared to normal subjects, the overt hypothyroid subgroup II patients (who were clinically asymptomatic with reduced serum free T4 index and elevated TSH) had a prolongation of ICT, PEP, and PEP/LVET (P less than or equal to 0.05), whereas the values in subclinical hypothyroid patients were similar to those in normal subjects. From these observations we conclude that in the absence of underlying heart disease, the echocardiographic method used is a rapid, reliable, and sensitive technique for determining STI and provides direct information on peripheral tissue thyroid functional status.

Thoracoscopy in the diagnosis of pleural effusions.

Between January 1981 and December 1986, thoracoscopies were carried out on 152 patients in order to evaluate the diagnostic accuracy of the technique in cases of pleural effusion. All patients had previously undergone a thoracentesis together with an unguided pleural biopsy but had remained undiagnosed. Of them, 74 cases were confirmed as malignant; the others were benign. In 71 of the 74 cases of malignant pleural effusion, an accurate diagnosis had been obtained from the thoracoscopy and guided pleural biopsy, a diagnostic accuracy of 94.6%. Among 78 cases, diagnosed by the thoracoscopy as benign pleural effusion, there were 63 cases of tuberculosis and 15 of non-specific pleurisy. Nine of the 15 cases of non-specific pleurisy showed no evidence of malignancy after being under observation for between six and 30 months, the remaining six cases being lost in the follow-up. No complication arose in our series. We conclude that thoracoscopy is a safe and useful diagnostic procedure for pleural effusion.

Effect of crotamine, a toxin of South American rattlesnake venom, on the sodium channel of murine skeletal muscle.

1 Crotamine (0.5 mug/ml) augmented the single twitch response of the rat and mouse isolated diaphragm to direct stimulation and prolonged the time course of contraction. At higher doses (10 to 50 mug/ml), contracture was observed with spontaneous fibrillation.2 The resting membrane potential of diaphragm was rapidly depolarized to about -50 mV within 5 minutes. No increase of depolarization occurred on prolongation of the incubation time or increase of crotamine concentration from 0.5 mug/ml to 50 mug/ml. The effect was not reversed by washing.3 Tetrodotoxin, low Na(+) (12 mM), Ca(2+) (10 mM) and procaine (1 mM) prevented the crotamine-depolarization. However, depolarization resumed when crotamine and the antagonists were removed.4 Low Cl(-) (8.5 mM) and pretreatment with ouabain enhanced depolarization by crotamine.5 High K(+) (25 to 50 mM) prevented the further depolarization by crotamine and the membrane potential was restored to normal on washout of crotamine with normal Tyrode solution.6 Effective membrane resistance was decreased by about 50% by crotamine.7(24)Na-influx of the rat diaphragm was increased by crotamine. (42)K-influx was slightly increased if tetrodotoxin was also present but was decreased in the absence of tetrodotoxin.8 No effect on the miniature and evoked endplate potential of the rat diaphragm was observed. Skeletal muscles from frog and chick were not affected.9 It is inferred that crotamine acts on a molecule regulating the Na(+) - permeability of the Na(+) channel of murine muscles. It is proposed that extracellular K(+) depresses the permeability of the Na(+) channel by acting on the same regulator molecule.