Building intelligent alarm systems by combining mathematical models and inductive machine learning techniques Part 2--sensitivity analysis

In an earlier study an approach was described to generate intelligent alarm systems for monitoring ventilation of patients via mathematical simulation and machine learning. However, ventilator settings were not varied. In this study we investigated whether an alarm system could be created with which a satisfactory classification performance could be obtained under a wide variety of ventilator settings, by varying inspiratory to expiratory time (I:E) ratio, tidal volume and respiratory rate. In a first experiment three patient data sets were modeled, each with a different I:E ratio. A part of each data set was used to construct an alarm system for each I:E ratio. The remaining part was used to test the performance of the alarm systems. The three training sets were also combined to construct one alarm system, which was tested with the three test sets. Finally, all alarm systems were tested with data generated by a patient simulator. Similar experiments were performed for the tidal volume and the respiratory rate. It was concluded that an optimally functioning alarm system should contain a library of rule sets, one for each set of ventilator settings. A second best alternative is to take all possible settings into consideration when constructing the training set. Classification performance of the trees that were trained with multiple ventilator settings ranged from 98 to 100% for all test sets. When tested with the independent patient simulator data the classification performance of these trees ranged from 80 to 100%.

Non-classical-MHC genetics of immunological disease in man and mouse. The key role of pro-inflammatory cytokine genes

For a series of immunological diseases including asthma, inflammatory arthritis and experimental allergic encephalomyelitis the non-classical major histocompatibility complex (MHC) genetics of man and mouse has been making rapid progress. Information is available not only for the disease associations of individual candidate genes but also from the first genome scans. In both species the proinflammatory cytokine genes and/or their related receptors and inhibitors (IL-1, IL-1r, IL-1ra, IL-2, IL-6r, TNF-alpha), and to a lesser extent the anti-inflammatory cytokine IL-4 are implicated as candidate control elements. In contrast, genes for the signalling and adhesion CD molecules have so far been inconspicuous. Most of the polymorphisms so far detected have been in the regulatory sequences of these genes, rather than in the exons. It is suggested that the benefit conferred on an individual by greater flexibility in its immunoregulatory machinery may be responsible for maintaining this form of polymorphism.

Unrepresentative behavior of T cell receptor-transgenic CD4+ T cells upon adoptive transfer: lack of need for priming and an extended booster dose-response

The response of CD4+ T cells taken from DO11.10 alpha beta TCR-transgenic mice to their specific antigen, ovalbumin, was examined in an adoptive transfer system. Read out was the % frequency of KJI-26.1+ (clonotype positive) cells within the Thy-1.2+ (T cell) population in lymph nodes. Control experiments indicated that these cells were uniformly CD4+. Immunizing the transgenic mice had no detectable effect on this frequency. Furthermore, the frequency in recipients of adoptively transferred lymph node cells was not affected by priming of the donors with ovalbumin by various procedures. Transfers were into syngeneic SCID recipients, except in one experiment, where irradiated recipients were shown to behave in the same way. Examining the effect of varying the amount of booster antigen, the response increased slowly with dose, up to a plateau in the range of 10-100 mg ovalbumin. The lack of need for priming is unusual, in comparison with an adoptive transfer of non-transgenic cells, as is the extended dose response range with such a high optimum dose. This enhanced responsiveness is interpreted in terms of a lack of down-immunoregulation in these transgenic mice.

Linkage studies in alcohol-responsive myoclonic dystonia

A large German family with "myoclonic dystonia with lightning jerks responsive to alcohol" was identified. Eleven affected pedigree members and six obligate gene carriers from five generations were identified. A description of one branch of this pedigree was published in 1964. Our examination 30 years after the initial report confirms the clinical syndrome of a nonprogressive movement disorder characterized by myoclonic jerks affecting the proximal muscles and the muscles of the trunk, accompanied by mild dystonic features in some affected family members. Segregation analysis favors autosomal dominant inheritance with high, but incomplete, penetrance in males and much lower penetrance in females. Linkage analysis was performed using simple sequence repeat polymorphisms (CA repeats) closely associated with or spanning the chromosomal regions containing 15 candidate genes: the gene for early-onset generalized torsion dystonia, DYT1 (chromosome 9q34); the genes for subunits alpha 2, beta 1, and gamma 1 (chromosome 4p12-4q13); for alpha 1, alpha 6, beta 2, and gamma 2 (chromosome 5q31.1-5q31.3); for alpha 4, alpha 5, beta 3, and gamma 3 (chromosome 15q11-15q13); for rho 1 and rho 2 (chromosome 6q14-6q21) of the gamma-aminobutyric acid A receptor; and for the alpha subunit of the glycine receptor (chromosome 5q31). By a combination of pairwise and multipoint linkage analysis, it could be excluded that any of these candidate gene-bearing chromosomal regions contain the disease gene in this family. We also excluded major portions of three chromosomal regions syntenic with mouse chromosome 3, which carries the murine beta subunit of the glycine receptor.

Inhibition of cytokine-inducible nitric oxide synthase in rat microglia and murine macrophages by methyl-2,5-dihydroxycinnamate

Microglial cells are resident macrophages in the central nervous system (CNS) which serve specific functions in the defence of the CNS against microorganisms, the removal of tissue debris in neurodegenerative diseases or during normal development, and in autoimmune inflammatory disorders of the brain. Microglia express a cytokine-inducible isoform of nitric oxide synthase, which leads to the production of nitric oxide (NO). Since NO is highly toxic to neurons and oligodendrocytes, we were interested to test down-regulating neuropeptides and second messenger de-activators in order to identify novel antagonists of cytokine-induced NO production. We found that only the tyrosine kinase inhibitor methyl-2,5-dihydroxycinnamate suppressed cytokine-induced NO production by rat microglial cells and murine macrophages, while a range of other tyrosine kinase inhibitors, neuropeptides and growth factors was ineffective. Since NO production may play a role in the pathogenesis of experimental neuro-immunological disorders like experimental autoimmune encephalomyelitis and experimental autoimmune neuritis, our findings suggest a possible therapeutic role for tyrosine kinase inhibitors.

p53 Protein exhibits 3'-to-5' exonuclease activity

Highly purified p53 protein from different sources was able to degrade DNA with a 3'-to-5' polarity, yielding deoxynucleoside monophosphates as reaction products. This exonuclease activity was dependent on Mg2+ and inhibited by addition of 5 mM nucleoside monophosphates. This exonuclease activity is intrinsic to the wild-type p53 protein: it copurified with p53 during p53 preparation; only purified wild-type p53, but not identically purified mutant p53 proteins displayed exonuclease activity; the exonuclease activity could be reconstituted from SDS gel-purified and urea-renatured p53 protein and mapped to the core domain of the p53 molecule; and finally, purified p53 protein could be UV-cross-linked to GMP. A p53-intrinsic exonuclease activity should substantially extend our view on the role of p53 as a "guardian of the genome."

Evolution of legumin genes: loss of an ancestral intron at the beginning of angiosperm diversification

The polymerase chain reaction was used to survey gymnosperm legumin genes. Characterization of 46 cloned amplificates, differing in sequence and size (1.2-1.6 kb), revealed the ubiquitous occurrence of legumin genes and their organization in small subfamilies in the 22 species investigated. The 3' portions of the genes, coding for the legumin beta-polypeptides, show a highly conserved intron/exon structure divergent from those of angiosperms: an additional intron (intron IV) uniformly interrupts the region coding for the C-terminal part of the beta-polypeptides. Phylogenetic analysis of the respective coding sequences as well as the organization of the Magnolia B14 legumin gene also investigated here both indicate that intron IV is ancestral and was lost during early angiosperm evolution. Taking into account the intron/exon structures from all legumin genes known, our results suggest that legumin genes evolved by subsequent loss of introns, providing also further evidence for a common origin of legumins and vicilins.

A novel sequence polymorphism in the promoter region of the human B2-bradykinin receptor gene

The distribution of a nucleotide polymorphism in the core promoter of the human B2-bradykinin receptor gene was examined in the population of southern Germany. The allelic frequencies were 0.595 for C allele and 0.405 for the T allele. The allele frequencies were in Hardy-Weinberg equilibrium. This new marker provides a valuable tool to assess the risk for putative bradykinin-associated disorders with genetic determinism.

Building intelligent alarm systems by combining mathematical models and inductive machine learning techniques

In this article a technique is described to develop knowledge-based alarm systems for ventilator therapy, using mathematical modeling and machine learning. With a mathematical model airway pressure, expiratory gas flow and CO2 concentration at the endotracheal tube are simulated for patients, undergoing volume-controlled ventilation with constant ventilator settings, during normal functioning of the breathing circuit and during breathing circuit mishaps (leaks and obstructions). Simulations were performed for 94 physiologically different 'patients', by varying airway resistance and lung/thorax compliance values in the model. Each simulated breath was described by a set of derived signal features and a label that constituted during which event (normal function or mishap) the breath was recorded. With an inductive machine learning algorithm rules, linking signal feature values to breathing circuit events, were created from data of 54 of the simulated patients. The resulting set of rules was able to classify 99% of events in the data of the remaining 40 patients correctly. Of signals, measured at a ventilated lung simulator, 100% of events were classified correctly.

[Early attachment experiences and behavioral problems in young children in a social and cognitive test situation]

In this article, the influence of quality of attachment (Ainsworth Strange Situation at 21 months) and of the intensity of attachment insecurity on test performance and emotional state in the test situation (Bayley-test at 20 months) are analyzed. The quality of attachment of 75 infants was classified according to Crittenden's PAA (Preschool Assessment of Attachment) as: secure (B), insecure defended (A) and insecure-coercive (C). Alternately, the infants were classified according to their intensity of insecurity of attachment across subtypes of qualities (secure, insecure, highly insecure). Securely attached (B) infants had the best Bayley Mental scores, were socially open and bodily relaxed. The insecure-defended (A) infants had moderate test results, were moderately open and tense, whereas the insecure-coercive (C) infants showed not only the worst test-results but were often withdrawn, fearful, tense, and poorly coordinated. Additional clinical signs of disorganization were spread unspecifically over all attachment groups particularly those of the insecure children. In the classification of children according to intensity of insecurity, these signs of disorganization accumulated particularly in the group of highly insecure infants. Children with highly insecure attachment who also exhibited unusual test situation behavior also had the lowest Bayley-test scores in the Mental Scale. These results are interpreted in the sense of balance between test engagement and emotional cost.

[Magnetic resonance tomography of the kidney: the testing of new pulse sequences and comparison with CT in the differential diagnosis of space-occupying lesions]

PURPOSE

To evaluate new pulse sequences (turbo-spin-echo [TSE] and turbo-field-echo [TFE] sequences) for study protocol optimisation and to assess the role of MRI in the differential diagnosis of renal tumours.

METHODS

In six volunteers MRI of the kidney was performed at 0.5 T using a conventional T2 weighted spin-echo (SE) sequence (TR/TE 1800/90 ms) and three different TSE sequences (TR 1800-5000 ms, TE 90-150 ms). Additionally CT and MRI was performed in 34 patients with 41 renal masses. Two readers evaluated both images regarding the differentiation between malignant and benign masses.

RESULTS

The pilot study showed that the heavily T2-weighted TSE sequence (TR/TE 5500/150 ms) was superior to other sequences with regard to image quality and differentiation of the corticomedullary junction. In the clinical study malignant tumours were correctly classified with CT and MRI in 86.4% and 95.5% of the cases, whereas the accuracy in the diagnosis of benign lesions of CT and MRI was 73.7% and 89.5%, respectively.

CONCLUSION

Using new puls sequences MRI is superior to CT in the differential diagnosis of renal tumours. MRI is superior to CT in the differentiation between complicated cysts and cystic or hypovascular renal cell carcinomas.

Population study of the G1691A mutation (R506Q, FV Leiden) in the human factor V gene that is associated with resistance to activated protein C

The mutation G1691A (R506Q) in the human factor V gene is associated with the resistance to activated protein C (APC) that represents a major risk of development of venous thrombosis. A population study of 180 unrelated individuals from south Germany was performed. Examination of the allelic frequencies revealed a high prevalence of this disease-related mutation (Q506, FV Leiden). The heterozygosity rate was 7.8% with a confidence interval between 4% and 11%.

Increase in the expression of alpha E beta 7, characteristic of intestinal intraepithelial lymphocytes, on T cells in the lung epithelium of patients with interstitial lung diseases and in synovial fluid of patients with rheumatic diseases

The intestinal epithelium contains a distinct group of lymphocytes (iIEL). The majority of iIEL are T cells characterized by a phenotype different from PBL. This phenotypic peculiarity has led to the hypothesis that iIEL, develop in a thymus-independent fashion, that they may develop locally in the gut epithelium itself and that they have the distinct function of providing a first line of defense in the gut. We looked at the expression of the gut-associated surface molecule alpha E beta 7 on T cells in inflamed tissues outside the gut epithelium. The already high frequency of 41.8% alpha E beta 7+ T cells in bronchoalveolar lavage from healthy lungs rises to a median of 61% in a fibrotic lung. In synovial fluid the percentage of T cells expressing alpha E beta 7 was diverse; it was not as high as in the lung but was elevated compared to PBL levels. In both tissues, the increase in alpha E beta 7 expression correlated with an increase in CD8+ cells. We discuss our data in the context of a model in which iIEL can leave the gut epithelium and become involved in inflammatory processes, possibly related to autoimmune disease.

Synthetic peptides coupled to the lipotripeptide P3CSS induce in vivo B and Thelper cell responses to HIV-1 reverse transcriptase

To evaluate the ability of the lipotripeptide P3CSS to increase peptide-specific immune responses in vivo, we immunized mice from different inbred strains (BALB/c, C3H/HeJ, C57BL/6) with the 22-mer lipopeptide conjugates P3CSS-[RT-(522-543)] and P3CSS-[RT-(528-549)] of HIV-1 reverse transcriptase (RT) which included an immunodominant Th epitope [i.e. RT-(528-543)] characterized previously. Analysis of T and B cell responses to these lipopeptide conjugates indicated that specific Th responses could be readily induced in vivo. The peptide segments could also efficiently prime mice for secondary recognition of native RT. The use of shorter peptides permitted a delineation of the minimal T cell recognition site of this RT C-terminal region [i.e. RT-(528-540)]. Close to this T cell epitope we identified a B cell determinant containing the motif EQVD [RT-(546-549)] which was recognized in three different strains of mice (H-2b, H-2d and H-2k). A comparison with X-ray analysis of the C-terminal region of HIV-1 reverse transcriptase indicated exposed positions of these Th and B cell epitopes. Both the presence of T and B cell sites and its limited polymorphism make the region RT-(528-549) a promising candidate for vaccine design. The use of the P3CSS adjuvant/carrier principle as a nontoxic adjuvant may be of major importance in the development of vaccines applicable to humans.

The RNA binding protein HuD: rat cDNA and analysis of the alternative spliced mRNA in neuronal differentiating cell lines P19 and PC12

HuD belongs to a family of neurospecific RNA binding proteins found in man, frog and fly [49]. To investigate whether this protein is involved in regulation of neuronal differentiation of rodent cells in vivo and in vitro, the cDNA of the rat homolog gene (r-HuD) was cloned, its expression was studied in rat brain and in neurogenic cell lines, and the splicing of its RNA was analyzed. Coding sequences of HuD from man and rat were found to be 99.5 and 95% identical at protein and DNA level, respectively. In rat brain r-HuD transcripts 3.7 and 4.2 kb in length were detected by Northern blot analysis. RT-PCR and in situ hybridization revealed that rodent homologues of HuD transcripts are present in P19 mouse embryo carcinoma and in PC12 rat pheochromocytoma cell lines both able to differentiate into neurons. In contrast, r-HuD transcripts were not detectable in the rat glioma cell line C6. In P19 cells a strong induction of HuD mRNA was observed after triggering neuronal differentiation by retinoic acid, whereas in PC12 cells the mRNA was present before and after nerve growth factor (NGF) induced neuronal differentiation. In both neuronal cell lines and in brain of adult rat and mouse HuD mRNA is alternatively spliced in a region which encodes a proline rich linker domain between the second and third RNA recognition motif. This RNA processing event seems to be differently regulated in PC12 cells on the one hand, and in P19 cells and brain of rat and mouse on the other.

Estimate of severe autosomal recessive limb-girdle muscular dystrophy (LGMD2C, LGMD2D) among sporadic muscular dystrophy males: a study of 415 familes

Ninety-five percent of cases of severe muscular dystrophy with early childhood onset result from mutations in the dystrophin region of the human X chromosome (DMD, McKusick 310200), whereas 5% are thought to result from mutations in autosomal genes. We examined a total of 415 families with at least one living patient whose clinical features suggested DMD. Based on formal genetics, haplotype analysis, and dystrophin determinations, we estimate that one in eight (11.8%) sporadic male patients carries autosomal rather than X chromosomal mutations.

Second-line treatment with high-dose 5-fluorouracil and folinic acid in advanced colorectal cancer refractory to standard-dose 5-fluorouracil treatment

Results with second-line treatment of advanced colorectal cancer are poor. Preliminary phase I/II results suggest encouraging response rates to high-dose 5-fluorouracil (FU) (2,600 mg/m2) combined with folinic acid (FA) in pretreated patients with advanced colorectal cancer. To determine the significance of weekly high-dose FU/FA in colorectal cancer refractory to weekly standard doses of FU/FA, a phase II study was initiated. 69 patients with metastatic colorectal cancer refractory to first-line weekly standard-dose FU/FA were treated with weekly high-dose FU 2,600 mg/m2 combined with FA 500 mg/m2 as a 2-hour infusion prior to FU application. Pretreatment was highly homogenous and consisted of weekly FU 500 mg/m2 combined with FA 500 mg/m2 or FA 20 mg/m2 or the pure stereoisomer of FA (6S-FA) 250 mg/m2. At the time of disease progression under first-line therapy, patients were transferred to high-dose FU/FA within 4 weeks. Treatment was continued until tumor progression under therapy was documented. Of the 69 evaluable patients, 17 (24.6%) achieved partial response (PR), 42 (60.9%) had no change (NC) and 10 (14.5%) had progressive disease under therapy. The median duration of PR was 7 months, the median time to progression of NC was 4 months. Median survival of all patients was 9 months, of patients with PR, 11.5 months. 33/38 patients with tumor-related pain experienced impressive relief under therapy. Prognostic factors for a beneficial outcome were complete response/PR under first-line therapy, a small number of metastatic sites and a good Karnofsky performance status. Moderate toxicity was observed, and the pattern of toxic events and severity did not differ from standard-dose FU regimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired action of thyroid hormone associated with smoking in women with hypothyroidism

BACKGROUND

The effect of smoking on thyroid function is controversial, and its effect on thyroid hormone action is unknown. We investigated the effects of cigarette smoking in women with various grades of hypothyroidism and in normal women.

METHODS

We studied 138 normal women and 135 women with primary hypothyroidism, of whom 84 had subclinical hypothyroidism and 51 overt hypothyroidism. Sixty of the women with hypothyroidism were reevaluated during thyroxine therapy. The women were categorized as smokers or nonsmokers according to their responses to a questionnaire. Thyroid function was evaluated by measurements of serum thyrotropin, free thyroxine, and triiodothyronine. Peripheral thyroid hormone action was assessed by a clinical score and measurements of ankle-reflex time and serum lipids and creatine kinase.

RESULTS

Among the women with subclinical hypothyroidism, the smokers had a higher mean (+/- SD) serum thyrotropin concentration (21.3 +/- 16.6 vs. 12.7 +/- 7.2 mU per liter, P = 0.004) and a higher ratio of serum triiodothyronine to serum free thyroxine (by 30 percent, P = 0.003) than the nonsmokers. Their serum concentrations of total cholesterol and low-density lipoprotein (LDL) cholesterol were higher (by 16 percent, P = 0.013; and 28 percent, P = 0.003, respectively). Among the women with overt hypothyroidism, the serum concentrations of thyrotropin, free thyroxine, and triiodothyronine were similar in the smokers and nonsmokers. As compared with the nonsmokers, the smokers had a clinical score indicating a greater degree of hypothyroidism (P < 0.001), higher serum concentrations of total and LDL cholesterol (by 25 percent, P < 0.001; and 24 percent, P = 0.002, respectively), longer ankle-reflex time (by 25 percent, P < 0.001), and higher serum concentrations of creatine kinase (by 236 percent, P < 0.001). There were dose-response relations between smoking and serum concentrations of total and LDL cholesterol, serum creatine kinase concentrations, and ankle-reflex time in the women with overt hypothyroidism, and between smoking and serum concentrations of total and LDL cholesterol in the women with subclinical hypothyroidism.

CONCLUSIONS

Smoking increases the metabolic effects of hypothyroidism in a dose-dependent way. This may be explained by alteration of both thyroid function and hormone action.