From Correlation to Causation: What Do We Need in the Historical Sciences?

Changes in the methodology of the historical sciences make them more vulnerable to unjustifiable speculations being passed off as scientific results. The integrity of historical science is in peril due the way speculative and often unexamined causal assumptions are being used to generate data and underpin the identification of correlations in such data. A step toward a solution is to distinguish between plausible and speculative assumptions that facilitate the inference from measured and observed data to causal claims. One way to do that is by comparing these assumptions against a well-attested set of aspects of causation, such as the so-called "Bradford Hill Criteria" (BHC). The BHC do not provide a test for causation or necessary and sufficient conditions for causation but do indicate grounds for further investigation. By revising the BHC to reflect the needs and focus of historical sciences, it will be possible to assess the cogency of methods of investigation. These will be the Historical Sciences Bradford Hill Criteria (HSBHC). An application to one area in historical science is used to demonstrate the effectiveness of the HSBHC, namely biogeography. Four methods are assessed in order to show how the HSBHC can be used to examine the assumptions between our data and the causal biogeographical processes we infer.

Label-free analysis of GPCR-stimulation: The critical impact of cell adhesion.

Label-free cell-based assays have been attracting growing attention in drug research. Optical approaches based on evanescent electric fields (e.g. EPIC, RWG/DMR, SPR) and electrochemical impedance analysis (ECIS, xCELLigence) are by far the most widespread techniques for such purposes. We compared three label-free approaches (ECIS, RWG/DMR and SPR) with respect to the activation of the human histamine H1 receptor (H1R) expressed by U-373 MG glioblastoma and genetically engineered HEK 293T cells. HEK 293T cells were either expressing the hH1R alone or in combination with the adhesion protein hMSR1. The ß2-adrenergic receptor (ß2-AR) expressed by bovine aortic endothelial cells (BAEC) served as a second cell model. Reduced cell adhesion to the surface of the sensing devices affected both, the optical and the impedance-based readout, but became much more obvious in case of RWG- or SPR-based assays. By contrast, the co-expression of hH1R and hMSR1 in HEK 293T cells strongly enhanced the signal compared to hH1R expression alone. As the sensitivity of the optical readouts is confined to a distance of 100-200nm from the surface, depending on the wavelength of the incident light, this observation is in accordance with tighter adhesion of the co-transfectants, inducing a shorter distance between the cell membrane and the substrate. Combining ECIS and SPR, allowing for simultaneous registration of both signals for a single cell population, provided a direct correlation of both readouts, when H1R or ß2-AR stimulation was investigated for the same cell populations. Cell adhesion was found to have a critical impact on the results of label-free cell monitoring, in particular when techniques based on evanescent electric fields are applied.

Label-free monitoring of cell-based assays: combining impedance analysis with SPR for multiparametric cell profiling.

Label-free approaches to monitor cell-based assays provide an unprecedented, time-resolved and non-invasive view on the response of mammalian cells to chemical, biological or physical stimuli. The most widespread techniques are impedance analysis and optical sensing using evanescent waves like SPR. This study describes the combination of both in one experimental setup so that a given cell population can be monitored simultaneously for electrical and optical changes. The device is based on commercial SPR chips that are processed by photolithography to provide electrodes for impedance analysis and gold spots for surface plasmon excitation on the same substrate. Simultaneous recordings do not interfere with each other but provide independent, time-resolved information on cell shape changes (impedance) and dynamic mass redistribution (SPR) as they occur during exposure of the cells to drugs or toxins or along their normal life cycle. This study provides proof-of-concept experiments of the dual biosensor platform in two experimental settings: signals are recorded and analyzed (i) during cell attachment, spreading and differentiation of initially suspended cells and (ii) during the exposure of the mature cells to an actin cytoskeleton disrupting drug. Impedance and SPR recordings provide complementary information that can be used to trace and assign intracellular mechanisms of action.

[PPI-sensitive diarrhea - unusual case of an adolescent with sporadic gastrinoma]. / Ansprechen einer episodenhaften chronischen Diarrhoe auf Protonenpumpenhemmer. Seltener Fall eines Jugendlichen mit sporadischem Gastrinom.

HISTORY AND CLINICAL FINDINGS: A 14-year-old boy was admitted to hospital because of chronic episodic diarrhea lasting for 4 years. Previous investigations in the past had not revealed the cause of the symptoms. INVESTIGATIONS: The 13C-triglyceride breathing test showed a diminished intestinal lipolysis. Endoscopic examination demonstrated small gastroduodenic ulcers. During therapy with proton-pump inhibitors the diarrhea stopped. DIAGNOSIS, TREATMENT AND COURSE: The combination of gastroduodenic ulcers and improvement of diarrhea with PPI-therapy were suggestive of Zollinger-Ellison syndrome. Endosonography and MR-scan showed an extrapancreatic mass with marked activity during somatostatin receptor scintigraphy. The primary tumor was excised, a liver metastasis was treated with radiofrequency ablation. The histological examination confirmed the diagnosis of a gastrinoma. CONCLUSION: In patients with chronic diarrhea, especially if the symptoms are PPI-sensitive, a gastrinoma should be considered.

Impact of intrapartal ultrasound to assess fetal head position and station on the type of obstetrical interventions at full cervical dilatation.

OBJECTIVES: Recent ultrasound studies have shown that it is feasible to objectively and reproducibly assess fetal head position and station within the pelvis. We sought to evaluate the impact of this new approach on decision making by physicians in a cohort of women with a prolonged second stage of labor. METHODS: This was a retrospective cohort study that included all women with fetuses in cephalic presentation, who were diagnosed with a prolonged second stage of labor, and who delivered in a 1-year period. We compared a group of women (n = 121) with a prolonged second stage of labor who underwent intrapartal ultrasound prior to obstetrical intervention (Group A, n = 43) with a group of women for whom the delivery modus was decided upon after clinical digital examination alone (Group B, n = 78). RESULTS: There were no significant differences in maternal and neonatal morbidity between both groups. The rate of second-stage cesarean section was significantly higher (p < 0.50) in Group B without ultrasound compared to Group A with ultrasound prior to operative delivery (20/78 vs. 7/43). Seven patients in Group A delivered spontaneously, but none of the patients in Group B had spontaneous deliveries. CONCLUSIONS: Intrapartal ultrasound in patients with a prolonged second stage of labor may change obstetrical practice by reducing the number of second stage cesarean section without increasing maternal and neonatal morbidity.

Measurement of fetal head descent using the 'angle of progression' on transperineal ultrasound imaging is reliable regardless of fetal head station or ultrasound expertise.

OBJECTIVES: To assess whether ultrasound experience or fetal head station affects the reliability of measurement of fetal head descent using the angle of progression on intrapartum ultrasound images obtained by a single experienced operator, and to determine reliability of measurements when images were acquired by different operators with variable ultrasound experience. METHODS: One experienced obstetrician performed 44 transperineal ultrasound examinations of women at term and in prolonged second stage of labor with the fetus in the occipitoanterior position. Three midwives without ultrasound experience, three obstetricians with < 5 years' experience and three obstetricians with > 10 years' experience measured fetal head descent based on the angle of progression in the images obtained. The angle of progression was measured by two obstetricians in independent ultrasound examinations of 24 laboring women at term with the fetus in the cephalic position to allow assessment of the reliability of image acquisition. Intraclass correlation coefficients (ICCs) with 95% confidence interval (CI) were used to evaluate interobserver reliability and Bland-Altman analysis was used to assess interobserver agreement. RESULTS: In total, 444 measurements were performed and compared. Interobserver reliability with respect to offline image analysis was substantial (overall ICC, 0.72; 95% CI, 0.63-0.81). ICCs were 0.82 (95% CI, 0.70-0.89), 0.81 (95% CI, 0.71-0.88) and 0.61 (95% CI, 0.43-074) for observers with > 10 years', < 5 years' and no ultrasound experience, respectively. There were no significant differences between ICCs among observer groups according to ultrasound experience. Fetal head station did not affect reliability. Bland-Altman analysis indicated reasonable agreement between measurements obtained by two different operators with > 10 years' and < 5 years' ultrasound experience (bias, -1.09 degrees ; 95% limits of agreement, -8.76 to 6.58). The reliability of measurement of the angle of progression following separate image acquisition by two experienced operators was similar to the reliability of offline image analysis (ICC, 0.86; 95% CI, 0.70-0.93). CONCLUSIONS: Measurement of the angle of progression on transperineal ultrasound imaging is reliable regardless of fetal head station or the clinician's level of ultrasound experience.

Disseminated toxoplasmosis in a patient with non-Hodgkin lymphoma.

Toxoplasmosis is a well-recognized opportunistic disease in HIV-infected individuals that is caused by the reactivation of a previous infection, primarily in the central nervous system, during profound immunodeficiency. Toxoplasmosis has been described more rarely in patients with cancer and chemotherapy. We report a case of a patient with a history of chemotherapy for non-Hodgkin lymphoma who developed pain and progressive paresthesia of the right arm 6 weeks after remission. Relapsing lymphoma was suspected, and steroid and radiation treatment were initiated, but the patient died 5 days later due to multiple organ failure. Autopsy revealed disseminated toxoplasmosis. This case illustrates that toxoplasmosis should be suspected in patients with neoplastic disease, especially lymphomas, who present with unexplained neurologic, pulmonary, or febrile symptoms during or after chemotherapy.

Transperineal ultrasound imaging in prolonged second stage of labor with occipitoanterior presenting fetuses: how well does the 'angle of progression' predict the mode of delivery?

OBJECTIVES: To compare the angle of progression on transperineal ultrasound imaging between different modes of delivery in prolonged second stage of labor with occipitoanterior fetal position. METHODS: We prospectively evaluated 41 women at term (>or= 37 weeks) with failure to progress in the second stage of labor. Only cases with occipitoanterior fetal position were included in the final analysis. These cases were classified into three groups: Cesarean section for failure to progress, vacuum extraction for failure to progress, and spontaneous delivery following prolonged second stage of labor. Transperineal ultrasound examination was performed just before digital examination and subsequent delivery. The angle between a line placed through the midline of the pubic symphysis and a line running from the inferior apex of the symphysis tangentially to the fetal skull (the so-called 'angle of progression') was measured offline by an observer blinded to the mode of delivery. RESULTS: There were 26 cases with occipitoanterior fetal position (Cesarean section, n = 5; vacuum extraction, n = 16; spontaneous delivery, n = 5). Logistic regression analysis showed a strong relationship between the angle of progression and the need for Cesarean delivery (R(2) measure of fit = 55%, likelihood ratio chi-square P < 0.0001). When the angle of progression was 120 degrees , the fitted probability of either an easy and successful vacuum extraction or spontaneous vaginal delivery was 90%. CONCLUSIONS: This is the first report to document a strong relationship between an objective ultrasound marker (angle of progression) and the mode of delivery following prolonged second stage of labor with occipitoanterior fetal position. A predictive model using this parameter would allow better decision making regarding operative delivery for obstructed labor.

Ets-1 is up-regulated together with its target gene products matrix metalloproteinase-2 and matrix metalloproteinase-9 in atypical and anaplastic meningiomas.

AIMS: Matrix metalloproteinases (MMPs) are a pivotal enzyme system involved in extracellular matrix (ECM) degradation and are considered to be important in the development and invasion of human tumours. Little is known about the regulation of MMPs in meningioma development and prognosis. The transcription factor Ets-1 is the main regulator of several MMPs, including MMP-2 and -9. The aim of this study was to determine the relationship between the expression of Ets-1, MMP-2 and -9 and the malignant potential of meningiomas. METHODS AND RESULTS: Seventy-four meningiomas of different histological grades were investigated immunohistochemically. Up-regulation of Ets-1, MMP-2 and MMP-9 expression was observed in atypical and anaplastic meningiomas. Invasive meningiomas showed increased immunohistochemical expression of these proteins compared with non-invasive meningiomas. We also observed a correlation between the expression of Ets-1 and of its target genes MMP-2 and MMP-9. CONCLUSIONS: Ets-1 may be involved in the transcriptional regulation of MMP-2 and MMP-9 as well as in the invasive process in meningiomas. Evaluation of these expressions might be of prognostic value for meningiomas.

Subcutaneous infection with Mycobacterium abscessus in a renal transplant recipient.

Transplant recipients show a high incidence of infections, often with atypical manifestations mainly because of drug-related immunosuppression. Mycobacterial infections can be life-threatening in immunosuppressed patients due to the risk of dissemination. There have been only few reports of cutaneous infections with Mycobacterium abscessus among immunosuppressed patients. We present a rare case with a sporotrichoid skin infection with M. abscessus in a renal recipient. The value of immunohistochemical detection of mycobacteria using an anti-BCG antibody in the diagnostic work-up skin biopsies is demonstrated. Long-term antibiotic treatment resulted in complete remission, although recurrences with atypical presentation were observed.

Evaluation of living conditions of free-ranging animals by automated chronobiological analysis of behavior.

A biorhythmical method has been developed to assess behavior patterns and to evaluate the living conditions of animals that can be applied also to humans. All kinds of continuous and equidistant long-term recordings of behavior are suitable for this method. Time functions from an automatic telemetry system (ETHOSYS II) were analyzed macroscopically (comparison of daily levels) and microscopically (autocorrelation function and power spectral analysis). Degrees of functional coupling (DFCs) were calculated to identify and evaluate disturbances in behavior. Hierarchic frequency tuning of complex rhythmic functions of behaviors, leads primarily to period lengths that are synchronized with the 24-h period. DFCs, a measure of harmony between internal rhythms and the external 24-h period, were found to be high in well-adapted, healthy, and undisturbed individuals but were lowered during periods of adaptation, sickness, or social interaction. Specific stress conditions could be identified and evaluated in several species, under various conditions, using these biorhythmic analyses.

Unusual manifestation of specific cutaneous involvement by B-cell chronic lymphocytic leukemia: spontaneous regression with scar formation.

We report a patient with specific cutaneous involvement by B-cell chronic lymphocytic leukemia, who demonstrated unusual clinical features during the course of the disease, namely several spontaneous regressions of skin lesions with the formation of scars. In addition, histologically proven keratoacanthoma was found. During the follow-up period of approximately 1.5 years, the patient experienced several recurrences of skin lesions and their partial spontaneous regression. The scars persisted and remained unchanged. We hypothesize that vascular injury combined with edema could have accounted for dermal ischemia and the subsequent development of the scarring lesions.

T-zone lymphoma with cutaneous involvement: a case report and review of the literature.

T-zone lymphoma (TZL) is a rare subtype of nodal peripheral T-cell lymphoma characterized by a clonal expansion of T-zone lymphocytes accompanied by a proliferation of other T-zone constituents. Non-specific cutaneous alterations are seen in about one-third of all cases, but specific cutaneous involvement is extremely rare. We present a case of TZL with secondary skin infiltration, review the literature on cutaneous manifestations of TZL and discuss the differential diagnosis of TZL.

Yeast as a model system for studying endocytosis.

Endocytosis is the membrane trafficking process by which plasma membrane components and extracellular material are internalized into cytoplasmic vesicles and delivered to early and late endosomes, eventually either recycling back to the plasma membrane or arriving at the lysosome/vacuole. The budding yeast Saccharomyces cerevisiae has proven to be an invaluable system for identifying proteins involved in endocytosis and elucidating the mechanisms underlying internalization and postinternalization events. Through genetic studies in yeast and biochemical studies in mammalian cells, it has become apparent that multiple cellular processes are linked to endocytosis, including actin cytoskeletal dynamics, ubiquitylation, lipid modification, and signal transduction. In this review, we will highlight the most exciting recent findings in the field of yeast endocytosis. Specifically, we will address the involvement of the actin cytoskeleton in internalization, the role of ubiquitylation as a regulator of multiple steps of endocytosis in yeast, and the sorting of endocytosed proteins into the recycling and vacuolar pathways.

The multispanning membrane protein Ste24p catalyzes CAAX proteolysis and NH2-terminal processing of the yeast a-factor precursor.

Saccharomyces cerevisiae Ste24p is a multispanning membrane protein implicated in the CAAX proteolysis step that occurs during biogenesis of the prenylated a-factor mating pheromone. Whether Ste24p acts directly as a CAAX protease or indirectly to activate a downstream protease has not yet been established. In this study, we demonstrate that purified, detergent-solubilized Ste24p directly mediates CAAX proteolysis in a zinc-dependent manner. We also show that Ste24p mediates a separate proteolytic step, the first NH(2)-terminal cleavage in a-factor maturation. These results establish that Ste24p functions both as a bona fide COOH-terminal CAAX protease and as an a-factor NH(2)-terminal protease. Importantly, this study is the first to directly demonstrate that a eukaryotic multispanning membrane protein can possess intrinsic proteolytic activity.

Topological and mutational analysis of Saccharomyces cerevisiae Ste14p, founding member of the isoprenylcysteine carboxyl methyltransferase family.

Eukaryotic proteins that terminate in a CaaX motif undergo three processing events: isoprenylation, C-terminal proteolytic cleavage, and carboxyl methylation. In Saccharomyces cerevisiae, the latter step is mediated by Ste14p, an integral endoplasmic reticulum membrane protein. Ste14p is the founding member of the isoprenylcysteine carboxyl methyltransferase (ICMT) family, whose members share significant sequence homology. Because the physiological substrates of Ste14p, such as Ras and the yeast a-factor precursor, are isoprenylated and reside on the cytosolic side of membranes, the Ste14p residues involved in enzymatic activity are predicted to be cytosolically disposed. In this study, we have investigated the topology of Ste14p by analyzing the protease protection of epitope-tagged versions of Ste14p and the glycosylation status of Ste14p-Suc2p fusions. Our data lead to a topology model in which Ste14p contains six membrane spans, two of which form a helical hairpin. According to this model most of the Ste14p hydrophilic regions are located in the cytosol. We have also generated ste14 mutants by random and site-directed mutagenesis to identify residues of Ste14p that are important for activity. Notably, four of the five loss-of-function mutations arising from random mutagenesis alter residues that are highly conserved among the ICMT family. Finally, we have identified a novel tripartite consensus motif in the C-terminal region of Ste14p. This region is similar among all ICMT family members, two phospholipid methyltransferases, several ergosterol biosynthetic enzymes, and a group of bacterial open reading frames of unknown function. Site-directed and random mutations demonstrate that residues in this region play a critical role in the function of Ste14p.

[Surgical palliation of pancreatic carcinoma. Results of a 7 year period]. / Chirurgische Palliation beim Pankreascarcinom. Ergebnisse aus einem 7-Jahresintervall.

INTRODUCTION: High perioperative complication rates in the 1980s led to preferred use of endoscopic therapy for surgical palliation of pancreatic cancer. This encouraged us to analyse our own patients retrospectively. MATERIAL AND METHODS: In the period from 1 January 1992 to 31 December 1998, 253 patients with an exocrine carcinoma of the pancreas were operated on at the St. Elisabeth Hospital Cologne-Hohenlind: 73 patients (28.9%) underwent curative resection (R0) while 180 patients (71.1%) had palliative operative treatment (R1/R2). Palliative resection was performed in 22 patients (8.7%). Intestinal bypass surgery was done in 113 patients (44.7%) as a gastrojejunostomy and in 16 patients (6.3%) as a duodenojejunostomy. A biliodigestive anastomosis was performed in 85 patients (33.6%). This procedure was combined with a gastroenterostomy in 78 patients (30.8%). In 18 patients (7.1%) no surgical palliation was possible and the operation finished as a diagnostic laparotomy. RESULTS: The overall mortality rate within the first 30 (60) days was 5.5% (12.7%). Patients whose carcinoma had been resected curatively had a 30 (60)-day mortality rate of 2.7% (4.1%), compared to a rate in palliatively treated patients (resection/bypass/probatoria) of 6.7% (16.1%). Patients with palliatively resected tumor had perioperative mortality of 4.5% (4.5%), whereas patients who did not undergo resection had 6.9% (17.7%). The survival rate for curatively resected patients after Kaplan-Meier extrapolation was 64.7% after 1 year and 31.2% and 26.2% after 3 and 5 years, with a median survival time of 552 days. Palliatively operated patients had a survival rate of 19.4%, 2.5% and 0% for 1, 3 and 5 years. Median survival time was 171 days in this situation. Compared to patients without resection (17.4% and 2.0%), patients with palliative resection had survival rates for 1 and 3 years of 40% und 5.9%. After 5 years none of these patients were alive. CONCLUSIONS: Our data show a high success of surgical palliation in pancreatic cancer in centers with a high frequency of pancreatic surgery. Patients that could not be cured (R1/R2), although undergoing extensive procedures, had better survival rates than patients treated with bypass surgery. Perioperative mortality rate was comparatively low. This justifies aggressive surgical management of pancreatic carcinoma.

The yeast a-factor transporter Ste6p, a member of the ABC superfamily, couples ATP hydrolysis to pheromone export.

ATP-binding cassette (ABC) proteins transport a diverse collection of substrates. It is presumed that these proteins couple ATP hydrolysis to substrate transport, yet ATPase activity has been demonstrated for only a few. To provide direct evidence for such activity in Ste6p, the yeast ABC protein required for the export of a-factor mating pheromone, we established conditions for purification of Ste6p in biochemical quantities from both yeast and Sf9 insect cells. The basal ATPase activity of purified and reconstituted Ste6p (V(max) = 18 nmol/mg/min; K(m) for MgATP = 0.2 mm) compares favorably with several other ABC proteins and was inhibited by orthovanadate in a profile diagnostic of ABC transporters (apparent K(I) = 12 microm). Modest stimulation (approximately 40%) was observed upon the addition of a-factor either synthetic or in native form. We also used an 8-azido-[alpha-(32)P]ATP binding and vanadate-trapping assay to examine the behavior of wild-type Ste6p and two different double mutants (G392V/G1087V and G509D/G1193D) shown previously to be mating-deficient in vivo. Both mutants displayed a diminished ability to hydrolyze ATP, with the latter uncoupled from pheromone transport. We conclude that Ste6p catalyzes ATP hydrolysis coupled to a-factor transport, which in turn promotes mating.

Chromosomal imbalances in gastric cancer. Correlation with histologic subtypes and tumor progression.

DNA copy number changes were analyzed by comparative genomic hybridization (CGH) in 38 gastric carcinomas and correlated with tumor histologic type and progression. Gains of copy numbers were observed in all tumors, affecting all chromosomes except chromosome 16. The average number of copy number gains was 7 (range, 1-13), most frequently located on chromosomes 11, 12, 15, 17, and 20 in 45% to 97% of tumors. High-level amplifications were found on chromosomes 12, 15, 17, and 20; the latter was affected most frequently (66%). Loss of DNA copy numbers was detected in 14 tumors affecting 7 chromosomes. No statistically significant differences in the frequency and pattern of chromosomal imbalances were observed in tumor histologic type (Lauren classification) and grade of differentiation, as well as the prognostic parameters depth of invasion (pT) and lymph node involvement (pN). Our results indicate that in gastric cancer there is no specific recurrent pattern of DNA aberrations to be correlated with tumor histologic type or stage. However, CGH analysis could reveal new, recurrent genetic changes in gastric cancer affecting chromosomes sites that harbor genes known to participate in tumorigenesis and progression of several human malignant neoplasms.