Reproductive individuality of clonal fish raised in near-identical environments and its link to early-life behavioral individuality

Recent studies have documented among-individual phenotypic variation that emerges in the absence of apparent genetic and environmental differences, but it remains an open question whether such seemingly stochastic variation has fitness consequences. We perform a life-history experiment with naturally clonal fish, separated directly after birth into near-identical (i.e., highly standardized) environments, quantifying 2522 offspring from 152 broods over 280 days. We find that (i) individuals differ consistently in the size of offspring and broods produced over consecutive broods, (ii) these differences are observed even when controlling for trade-offs between brood size, offspring size and reproductive onset, indicating individual differences in life-history productivity and (iii) early-life behavioral individuality in activity and feeding patterns, with among-individual differences in feeding being predictive of growth, and consequently offspring size. Thus, our study provides experimental evidence that even when minimizing genetic and environmental differences, systematic individual differences in life-history measures and ultimately fitness can emerge.

Impact of genetic relatedness on reproductive behavior in Pelvicachromis pulcher, a biparental cichlid fish with mutual mate choice and ornamentation

Inbreeding can result in inbreeding depression. Therefore, many species seek to avoid inbreeding. However, theory predicts that inbreeding can be beneficial. Accordingly, some species tolerate inbreeding or even prefer mating with close relatives. Evidence for active inbreeding, i.e., kin-mating preference was reported in the biparental African cichlid fish Pelvicachromis taeniatus. Related mating partners revealed better parental cooperation due to kin selection, a potential benefit of inbreeding. In this study, we investigated kin-mating preference in a genetically diverse, outbred F2-lab population of Pelvicachromis pulcher, a closely related species to P. taeniatus. Like P. taeniatus, this species shows mutual ornamentation and mate choice as well as intense biparental brood care. The F1 P. pulcher generation had revealed signs of inbreeding depression but no inbreeding avoidance. We studied mating behavior and aggression in trios consisting of a male P. pulcher, an unfamiliar sister, and an unfamiliar, unrelated female. Because the study focused on kin-mating patterns, female pairs were matched for body size and coloration. The results provide no evidence for inbreeding avoidance but rather suggest inbreeding preference. We also found no significant impact of inbreeding on offspring survival. The results suggest no inbreeding avoidance in P. pulcher; however, the strength of inbreeding preference and inbreeding depression seems to be variable. We discuss possible causes for this variation like context-dependent inbreeding depression. The number of eggs positively correlated with female body size and coloration. Furthermore, the female aggressiveness was positively correlated with female coloration indicating that coloration signal female dominance and quality.

Leveraging big data to uncover the eco-evolutionary factors shaping behavioural development

Mapping the eco-evolutionary factors shaping the development of animals' behavioural phenotypes remains a great challenge. Recent advances in 'big behavioural data' research-the high-resolution tracking of individuals and the harnessing of that data with powerful analytical tools-have vastly improved our ability to measure and model developing behavioural phenotypes. Applied to the study of behavioural ontogeny, the unfolding of whole behavioural repertoires can be mapped in unprecedented detail with relative ease. This overcomes long-standing experimental bottlenecks and heralds a surge of studies that more finely define and explore behavioural-experiential trajectories across development. In this review, we first provide a brief guide to state-of-the-art approaches that allow the collection and analysis of high-resolution behavioural data across development. We then outline how such approaches can be used to address key issues regarding the ecological and evolutionary factors shaping behavioural development: developmental feedbacks between behaviour and underlying states, early life effects and behavioural transitions, and information integration across development.

Developmental feedbacks and the emergence of individuality

Behavioural individuality is a hallmark of animal life, with major consequences for fitness, ecology, and evolution. One of the most widely invoked explanations for this variation is that feedback loops between an animal's behaviour and its state (e.g. physiology, informational state, social rank, etc.) trigger and shape the development of individuality. Despite their often-cited importance, however, little is known about the ultimate causes of such feedbacks. Expanding on a previously employed model of adaptive behavioural development under uncertainty, we find that (i) behaviour-state feedbacks emerge as a direct consequence of adaptive behavioural development in particular selective environments and (ii) that the sign of these feedbacks, and thus the consequences for the development of behavioural individuality, can be directly predicted by the shape of the fitness function, with increasing fitness benefits giving rise to positive feedbacks and trait divergence and decreasing fitness benefits leading to negative feedbacks and trait convergence. Our findings provide a testable explanatory framework for the emergence of developmental feedbacks driving individuality and suggest that such feedbacks and their associated patterns of behavioural diversity are a direct consequence of adaptive behavioural development in particular selective environments.

Developmental feedbacks and the emergence of individuality

Behavioural individuality is a hallmark of animal life, with major consequences for fitness, ecology, and evolution. One of the most widely invoked explanations for this variation is that feedback loops between an animal's behaviour and its state (e.g. physiology, informational state, social rank, etc.) trigger and shape the development of individuality. Despite their often-cited importance, however, little is known about the ultimate causes of such feedbacks. Expanding on a previously employed model of adaptive behavioural development under uncertainty, we find that (i) behaviour-state feedbacks emerge as a direct consequence of adaptive behavioural development in particular selective environments and (ii) that the sign of these feedbacks, and thus the consequences for the development of behavioural individuality, can be directly predicted by the shape of the fitness function, with increasing fitness benefits giving rise to positive feedbacks and trait divergence and decreasing fitness benefits leading to negative feedbacks and trait convergence. Our findings provide a testable explanatory framework for the emergence of developmental feedbacks driving individuality and suggest that such feedbacks and their associated patterns of behavioural diversity are a direct consequence of adaptive behavioural development in particular selective environments.

Developmental feedbacks and the emergence of individuality

Behavioural individuality is a hallmark of animal life, with major consequences for fitness, ecology, and evolution. One of the most widely invoked explanations for this variation is that feedback loops between an animal's behaviour and its state (e.g. physiology, informational state, social rank, etc.) trigger and shape the development of individuality. Despite their often-cited importance, however, little is known about the ultimate causes of such feedbacks. Expanding on a previously employed model of adaptive behavioural development under uncertainty, we find that (i) behaviour-state feedbacks emerge as a direct consequence of adaptive behavioural development in particular selective environments and (ii) that the sign of these feedbacks, and thus the consequences for the development of behavioural individuality, can be directly predicted by the shape of the fitness function, with increasing fitness benefits giving rise to positive feedbacks and trait divergence and decreasing fitness benefits leading to negative feedbacks and trait convergence. Our findings provide a testable explanatory framework for the emergence of developmental feedbacks driving individuality and suggest that such feedbacks and their associated patterns of behavioural diversity are a direct consequence of adaptive behavioural development in particular selective environments.

Do female rainbow kribs choose males on the basis of their apparent aggression and boldness? A non-correlational mate choice study

Abstract

Consistent between-individual differences in behaviour, known as personality differences, are heritable and have consequences for individual survival and reproductive success. Therefore, it is likely that personality differences are not just under natural but also under sexual selection. Indeed, the recently developed idea that individuals choose their mate based on its personality finds empirical support. However, most studies on mate choice based on personality traits are correlative pioneering work and there is a paucity of experimental studies that test for causality by disentangling personality measures from other, potentially correlated traits that may be important during mate choice. Here, we tested female preference for the apparent level and consistency of either male aggression (measured as mean distance of approach towards an animated opponent, manipulated by locating males at a fixed distance) or male boldness (measured as activity under a simulated predation threat, manipulated using a gradient in ambient water temperature) in a bi-parental West African cichlid, Pelvicachromis pulcher. Females could observe the apparent behaviour of paired stimulus males and were allowed to choose between the two stimulus males in a subsequent choice test. We found no direct effect of male apparent aggression/boldness on female choice, but an indirect effect such that female preference for the apparently bold male increased with increasing within-male pair contrast in their apparent level of boldness. Our results indicate females consider male boldness per se during mate choice, suggesting male boldness is sexually selected in our study species.

Significance statement

Ever since Darwin introduced the concept of sexual selection, female choice has been studied extensively. However, the hypothesis that consistent between-individual differences in behaviour (known as personality differences) affect mate choice is relatively new. Correlative studies support this idea but provide only suggestive evidence. Here, we used behavioural manipulations in order to disentangle male behaviour from other, potentially correlated male traits, allowing us to test for causality between female choice and personality differences in male aggression and boldness (both in level and consistency of behaviour) in a bi-parental cichlid. We found no overall female preference for male apparent behaviour, but female preference for the bold-appearing male increased with increasing between-male contrast in apparent boldness. Our results indicate a causal link between female choice and male boldness. In future, behavioural manipulations using a temperature gradient could provide further valuable insights.

No male mate choice for female boldness in a bi-parental West African cichlid, the rainbow krib (Pelvicachromis pulcher)

Background

In many species, males have a lower reproductive investment than females and are therefore assumed to increase their fitness with a high number of matings rather than by being choosy. However, in bi-parental species, also males heavily invest into reproduction. Here, reproductive success largely depends on costly parental care; with style and amount of parental effort in several cases being associated with personality differences (i.e., consistent between-individual differences in behaviour). Nonetheless, very little is known about the effect of personality differences on (male) mate choice in bi-parental species.

Methods

In the present study, we tested male mate choice for the level and consistency of female boldness in the rainbow krib, Pelviachromis pulcher, a bi-parental and territorial West African cichlid. Individual boldness was assumed to indicate parental quality because it affects parental defence behaviour. For all males and females, boldness was assessed twice as the activity under simulated predation risk. Mate choice trials were conducted in two steps. First, we let a male observe two females expressing their boldness. Then, the male could choose between these two females in a standard mate choice test.

Results

We tested for a male preference for behavioural (dis-)similarity vs. a directional preference for boldness but our data support the absence of effects of male and/or female boldness (level and consistency) on male mating preference.

Discussion

Our results suggest female personality differences in boldness may not be selected for via male mate choice.

Male size, not female preferences influence female reproductive success in a poeciliid fish (Poecilia latipinna): a combined behavioural/genetic approach

Objective

We investigated the potential role of indirect benefits for female mate preferences in a highly promiscuous species of live-bearing fishes, the sailfin molly Poecilia latipinna using an integrative approach that combines methods from animal behavior, life-history evolution, and genetics. Males of this species solely contribute sperm for reproduction, and consequently females do not receive any direct benefits. Despite this, females typically show clear mate preferences. It has been suggested that females can increase their reproductive success through indirect benefits from choosing males of higher quality.

Results

Although preferences for large body size have been recorded as an honest signal for genetic quality, this particular study resulted in female preference being unaffected by male body size. Nonetheless, larger males did sire more offspring, but with no effect on offspring quality. This study presents a methodical innovation by combining preference testing with life history measurements—such as the determination of the dry weight of fish embryos—and paternity analyses on single fish embryos.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3487-2) contains supplementary material, which is available to authorized users.

Predictability is attractive: Female preference for behaviourally consistent males but no preference for the level of male aggression in a bi-parental cichlid

Although personality traits can largely affect individual fitness we know little about the evolutionary forces generating and maintaining personality variation. Here, we investigated the hypothesis that personality variation in aggression is sexually selected in the monogamous, bi-parental cichlid Pelvicachromis pulcher. In this species, breeding pairs form territories and they aggressively defend their territory and offspring against con- and heterospecific intruders. In our mate choice study, we followed up two alternative hypotheses. We either expected females to show a directional preference for a high level and high consistency of aggression (potentially indicating mate choice for male parental quality). Alternatively, we expected females to choose males for (dis-)similarity in the level/consistency of aggression (potentially indicating mate choice for compatibility). Individual level and consistency of aggression were assessed for males and females using mirror tests. After eavesdropping on aggressive behaviour of two males (differing in level and consistency of aggression) females were then allowed to choose between the two males. Males, but not females, showed personality variation in aggression. Further, females generally preferred consistent over inconsistent males independent of their level of aggression. We did not detect a general preference for the level of male aggression. However, we found an above average preference for consistent high-aggression males; whereas female preference for inconsistent high-aggression did not deviate from random choice. Our results suggest behavioural consistency of aggression in male rainbow kribs is selected for via female mate choice. Further, our study underlines the importance of considering both the level and the consistency of a behavioural trait in studies of animal behaviour.

A parsimonious approach to estimate PAH concentrations in river sediments of anthropogenically impacted watersheds

The contamination of riverine sediments and suspended matter with hydrophobic pollutants is typically associated with urban land use. However, it is rarely related to the sediment supply of the watershed, because sediment yield data are often missing. We show for a suite of watersheds in two regions of Germany with contrasting land use and geology that the contamination of suspended particles with polycyclic aromatic hydrocarbons (PAH) can be explained by the ratio of inhabitants residing within the watershed and the watershed's sediment yield. The modeling of sediment yields is based on the Revised Universal Soil Loss Equation (RUSLE2015, Panagos et al., 2015) and the sediment delivery ratio (SDR). The applicability of this approach is demonstrated for watersheds ranging in size from 1.4 to 3000km². The approach implies that the loading of particles with PAH can be assumed as time invariant. This is indicated by additional long-term measurements from sub-watersheds of the upper River Neckar basin, Germany. The parsimonious conceptual approach allows for reasonable predictions of the PAH loading of suspended sediments especially at larger scales. Our findings may easily be used to estimate the vulnerability of river systems to particle-associated urban pollutants with similar input pathways as the PAH or to indicate if contaminant point sources such as sites of legacy pollution exist in a river basin.

Cellulose Synthesis and Cell Expansion Are Regulated by Different Mechanisms in Growing Arabidopsis Hypocotyls

Plant growth is sustained by two complementary processes: biomass biosynthesis and cell expansion. The cell wall is crucial to both as it forms the majority of biomass, while its extensibility limits cell expansion. Cellulose is a major component of the cell wall and cellulose synthesis is pivotal to plant cell growth, and its regulation is poorly understood. Using periodic diurnal variation in Arabidopsis thaliana hypocotyl growth, we found that cellulose synthesis and cell expansion can be uncoupled and are regulated by different mechanisms. We grew Arabidopsis plants in very short photoperiods and used a combination of extended nights, continuous light, sucrose feeding experiments, and photosynthesis inhibition to tease apart the influences of light, metabolic, and circadian clock signaling on rates of cellulose biosynthesis and cell wall biomechanics. We demonstrate that cell expansion is regulated by protein-mediated changes in cell wall extensibility driven by the circadian clock. By contrast, the biosynthesis of cellulose is controlled through intracellular trafficking of cellulose synthase enzyme complexes regulated exclusively by metabolic signaling related to the carbon status of the plant and independently of the circadian clock or light signaling.

Artificial Visible Implant Elastomer (VIE) tags of different colour and symmetry do not influence mate choice in a cichlid

Experimental individuals are frequently marked with coloured tags for individual identification. Except for birds, the consequences of such artificial tagging on mate choice have been rarely investigated even though individuals often prefer naturally brightly coloured or symmetrically ornamented mates. We tested whether differently coloured Visible Implant Elastomer (VIE) tags influence female mate choice in rainbow kribs,Pelvicachromis pulcher. Females were allowed to simultaneously choose between a control and a VIE-marked male. The VIE-marked male carried two tags of the same colour (red, blue, green or white) set symmetrically or asymmetrically. Females did not show a preference for or avoidance of males carrying any of the colours compared to control males, no matter if the tags had been set symmetrically or asymmetrically. Although we found no discrimination for or against colour-tags, we highlight the importance of considering potential influences of colour-marks on mate choice in behavioural and evolutionary studies.

Lateralisation in agonistic encounters: do mirror tests reflect aggressive behaviour? A study on a West African cichlid

In this study, population level lateralisation and the suitability of mirror tests as a test of natural aggressive behaviour in male rainbow kribs Pelvicachromis pulcher was investigated. Aggressive behaviour in live agonistic trials correlated positively with behaviours towards a mirror image and no visual lateralisation was detected.

Emissions of heavy metals into river basins of Germany

The input of seven heavy metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn) into the large river basins of Germany via various point and diffuse pathways were estimated for the period of 1985 through 2000. To quantify the emissions via point sources a nationwide survey on heavy metal data of municipal wastewater treatment plants and industrial direct discharges was carried out. The input via diffuse pathways was calculated using an adapted version of the model MONERIS. This model accounts for the significant transport processes, and it includes a Geographical Information System (GIS) that provides digital maps as well as extensive statistical information. For a comparison of the calculated heavy metal emission with the measured heavy metal load at monitoring stations the losses of heavy metals due to retention processes within the river systems have to be considered. Therefore heavy metal retention was calculated according to the retention functions given by Vink and Behrendt. For the large river basins a good correspondence could be found between estimated and measured heavy metal loads in rivers. The total emission into the North Sea decreased for each metal during the period of 1986 to 2000. The reduction varies between 87% for Hg and 41% for Ni mainly caused by the decline via point sources. Today's emissions of heavy metals into river basins of Germany are dominated by the input via diffuse pathways. The most important diffuse emission pathways are "paved urban areas" and "erosion".

Coping strategies, personality, and voice quality in patients with vocal fold nodules and polyps

Emotional state affects the physiological mechanism involved in phonation. Differences in acoustical parameters of the voice under stress have been attributed to the coping mechanism used, which is based on the individual's perception of the situation. This study examines the relationship between coping strategies, personality, and voice in female subjects, ranging in age from 19.3-55.7 years, diagnosed with vocal nodules or polyps. The differences between coping strategies and personality are examined and compared with another group with no history of voice pathology. The relationship of personality and coping strategies to voice quality variables is reported. Results show that patients use emotional coping strategies more and cognitive coping strategies less than the comparison group. Type of voice pathology was found to be related to dominance, and a number of coping and personality variables were found to correlate significantly with voice quality.

[Echographic findings in cyclitis annularis pseudotumorosa and ring melanoma of the ciliary body]

Ring melanomas can closely simulate annular choroidal detachments ophthalmoscopically. In A-scan sonography the malignant melanoma of the ciliary body is characterized by low to medium reflectivity, whereas annular choroidal detachment manifests no internal reflectivity.

[Echographic diagnosis of orbital floor fractures]

In this study symptoms of fractures of the orbital floor are described. The problems of diagnosis by x-ray are demonstrated. There is no evidence of bony fractures in many cases in standard x-ray pictures. Diagnosis of fractures of the orbital floor is established in most patients by polytomography. This method, however, implicates the disadvantage of high radiation exposure. Experimental studies have shown that fractures of a width of at least 1 mm. and bony fragments greater than 1 X 1 mm. can be visualized in the B-scan. All 62 cases of fractures of the orbital floor found intraoperatively had been diagnosed by ultrasound before surgery.

[Computer tomographic diagnosis of liver diseases]

Computed tomography is one out of several imaging procedures used in the detection of liver disease (radionuclide imaging, ultrasound). It is a noninvasive technique convenient for the patient and generally an outpatient procedure. Many focal lesions and some diffuse liver disease are characterized by a specific pattern. For space-occupying lesions, the diagnostic accuracy ranges between 86 and 95 percent.

[Artifacts in A and B-scan echograms following the implantation of artificial lenses]

In the A scan and B scan echogram of the eye and orbit artifacts may arise following implantation of an intraocular lens. Their origin, form, and localization can be explained by means of physics. Reverberation, foreign body, refraction, and absorption artifacts can be distinguished; familiarity with their appearance will avoid erroneous interpretation and results.

[Intracranial manifestations of lymphogranulomatosis]

Intracerebral manifestations of Hodgkin's disease are rare. They may occur as a primary or secondary manifestation and cause a variety of neurological symptoms. Frequently other organs as lungs, liver, bones and gastrointestinal tract are involved. Computer tomography and scintigraphy of the brain are valuable tools to help establish the diagnosis. Most patients have a poor prognosis. The treatment of choice is radiation of the brain. The literature of 34 reported cases is reviewed and two own cases are reported.

Computed tomography for localizing enlarged parathyroid glands in primary hyperparathyroidism

Computed tomography (CT) has been performed in 21 patients with primary hyperparathyroidism (HPT) in an attempt to localize preoperatively the parathyroid tumors. Eighteen of these patients also had ultrasound examinations. The CT examinations included the neck and mediastinum and were performed before and after contrast medium administration. At subsequent surgery, 24 enlarged glands were found, 20 in the neck and 4 in the mediastinum. In the neck, two were locally recurrent carcinomas. The true positive diagnostic rate for ultrasound was 60% with a false positive rate of 15% and a false negative rate of 25%. The CT examinations resulted in 70.9% true positive, 8.3% false positive, and 20.8% false negative diagnoses. The combination of both methods in the 18 patients so studied resulted in 80% true positive, 10% false positive, and 10% false negative findings. The CT examination procedure and its interpretation and limitations in primary HPT are described.

[Clinical value of bronchoalveolar lavage in progressive systemic scleroderma (author's transl)]

As an enlargement of conventional diagnostic methods the cell spectrum of bronchoscopically obtained bronchoalveolar lavage was investigated in 10 patients with progressive systemic scleroderma. Two cases showed marked lymphocytosis, one increased numbers of granulocytes, two patients had marginally increased percentages of inflammatory cells. Four of these patients were in a progressive active phase of scleroderma with humoral inflammation signs and round cell infiltrates of the skin. In contrast, the lavage cell picture of the other five patients was unremarkable. One of these had advanced pulmonary fibrosis, however without signs of progression. The results show that the lavage cell pattern reflects the acute phase with cellular inflammation of lung parenchyma disease such as occurs in progressive systemic scleroderma. Staging of pulmonary organ manifestation in progressive systemic scleroderma can be markedly improved by low-risk bronchoalveolar lavage.

CT studies of the liver in vitro: a report on 82 cases with pathological correlation

Eighty-two liver specimens were studied by both computed tomography (CT) and pathological examination with serial sectioning. In vitro CT studies showed low density structures within 57 normal livers to be due to portal and hepatic vessels but not to bile ducts. A liver with a minimum of 70% fatty infiltration could be diagnosed correctly on CT. Concerning the presence or absence of circumscribed liver disease, sensitivity was 80% and specificity was 84%. With respect to the total number of space occupying liver lesions (n = 364 in 18 specimens), sensitivity was 72%. The smallest metastases detectable on CT were 0.5 cm in diameter, but CT disclosed focal lesions of this small size in only 15% of the cases. In contrast to previously reported in vivo CT studies, metastases were often found to be of higher density than normal liver tissue in vitro.

[Liver and ovulation inhibitors. Effects on liver function of estrogen-progestagen containing steroid oral contraceptives]

Since introduction of oral contraceptive steroids a variety of physiologic-adaptive and toxic side effects have been reported. -a review is given. The study reports also four cases of hepatic vein thrombosis (Budd-Chiari-Syndrome--Venoocclusive disease) and three cases of benign hepatic tumors (liver cell adenoma and focal nodular hyperplasia) in young women following 2- to 5-year treatment with oral contraceptive steroids.

[Computerized tomography of the liver. Accuracy of the method in biopsy proven diagnoses (author's transl)]

To evaluate the diagnostic accuracy of computerized tomography (CT) in detecting liver disease, CT-findings of 320 patients examined with a slow CT-scanner (2.5 min scanning time/slice) could be compared to the results of bioptic procedures. Sensitivity was 81% for circumscript liver disease, specificity was 85%. In 69% of the cases, a type-specific diagnosis of circumscript liver diseases was possible, this percentage increased by 5% if patients with a true-positive differential diagnosis were included. 73% of the patients with liver metastases were correctly identified to have metastatic liver disease. Obstructive jaundice was correctly identified in 77% and correctly excluded in all patients with medical jaundice. For a large variety of hepatocellular disease, ratio of true positive diagnoses was 16% only. The value of CT in hepatocellular disease concerns exclusion of presumed space-occupying lesions. In a control group of 310 patients with only "clinically" and not bioptically confirmed diagnoses, specificity was 96% and sensitivity concerning focal liver disease was 82%. Our results prove CT to be a valuable non-invasive tool in the evaluation of circumscript liver disease.

[Value of computerized tomography in diseases of liver and spleen]

A survey has been given regarding the position of the CT as a examination method of liver, gallbladder - bile duct system and spleen. A fast scanner of the third generation has been used and has been compared with results of a slow CT of the first generation.

Computed tomography in hydatid disease of the liver: a report on 13 cases

Computed tomography (CT) findings in hydatid disease (echinococciasis) of the liver are described. Disease was caused by Echinococcus granulosus (n = 8) or E. alveolaris (n = 5), respectively. The CT appearance of these two types of echinococciasis is quite different; in disease caused by E. granulosus the CT appearance is pathognomonic when cysts and daughter cysts surrounded by a capsula and peripheral calcification are discernible. In addition, the extent of organ involvement can be determined prior to surgical intervention. The CT appearance of E. alveolaris lesions may be indiscernible from malignant tumors.

Computerized tomography and nuclear imaging of the liver: a comparative study in 83 cases

This study was performed to comparatively assess the diagnostic accuracy of computerized tomography (CT) and nuclear liver-scanning in detecting and defining circumscript and diffuse liver diseases in 83 patients. Presence or absence of liver diseases was assessed based on the results of invasive diagnostic procedures such as biopsy, laparoscopy, laparotomy, and/or autopsy. The percentage of true negative diagnoses was 94% for CT and 91% for static gamma-imaging (n = 33). With a rate of 94% true positive diagnoses, CT proved to be superior to gamma imaging with radiocolloids (81% true positives) in diagnosing circumscript liver diseases (n = 31). In addition. CT was superior to nuclear imaging regarding discrimination of number and size of space-occupying lesions within the liver. In contrast to nuclear screening, CT scans were pathognomonic to some circumscript liver diseases such as cysts, metastases, and perhaps echinococciasis. This was also true for obstructive jaundice. Nuclear imaging, because it reflects a sort of liver function, was superior with cirrhosis, whereas CT showed only alterations in the size and shape of the liver and spleen.

Diagnostic accuracy of CT in circumscript liver disease

To evaluate the accuracy of CT in diagnosing circumscript liver disease, CT findings in 105 patients were compared to the results of invasive diagnostic procedures (laparoscopy, laparotomy, and autopsy). In all patients at least one of these procedures was performed in addition to CT. CT proved to be a valuable noninvasive method in detecting and differentiating circumscript liver lesions such us metastases, primary liver tumors, solitary cysts and polycystic disease, abscesses, and echinococciasis. The 10% rate of false positive and false negative diagnoses indicates the limitations of the method.

[Special indications for using the whole body scanner (author's transl)]

In addition to the role of the body scanner in the diagnosis of diseases of the body cavity and parenchymal organs, the authors review the scope and indications for using whole body computer tomography in special situations. Examples are given of its use in the diagnosis of tumours in the vicinity of the skull base, in the orbits, the facial skeleton, soft tissue tumours, bone diseases and CT-controlled biopsies.

[Computerised tomography of the trunk-a first report (author's transl)]

One thousand patients have been examined with the body scanner and a preliminary report is presented on the value of this method in the examination of abdomen and the thorax. Unlike other radiological procedures, computerised tomography is often able to demonstrate disease states directly and not only as a result of their effect on neighbouring structures. It provides a non-invasive means for achieving a diagnosis, for therapy planning and for control of treatment of space-occupying lesions within the trunk. Its role can only be defined after a systematic comparision with conventional diagnostic procedures.

[The informative value of diagnostic methods in chronic headache. A study of 112 cases (author's transl)]

A thorough neurological diagnostic investigation was carried out in 112 patients with chronic headache existing for an average of 14 years, using a case history questionnaire we had designed for the purpose. Apart from the history and clinical examination, the program included X-ray negatives, angiography, computer tomography, sequence scanning, electroencephalogram and echoencephalogram. Migraine was the most common diagnosis (54.5%). Three cases in which admission to a ward was necessary for more detailed examination are described and demonstrated with reference to neuroradiological illustrative material.

[Clinical experience with a 30 cm. image intensifier with special reference to a 100 mm. film technique (author's transl)]

The report deals with one year's experience of two new 30 cm. image intensifiers with special reference to a 100 mm. film technique. Attention was paid to its applicability to routine work and the usefulness of this format when demonstrated to a large audience. Comparative dose measurements using the image intensifier and a direct film technique are given. The running costs have been analysed. Suggestions for further improving the technique using this format are given.