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Biomedical subjects

F W Röhl

Publications and source records attributed to F W Röhl.

17 recordsLinked to original sources
PubMed2007

[Validity of a web-based color vision test for screening examinations of color vision].

BACKGROUND: With standardized examination conditions, a web-based color vision test using pseudoisochromatic color plates can deliver test results comparable to those yielded by conventional color vision tests. The aim of the study is to analyze to what extent a web-based color vision test can be used as a screening test on the internet after visual monitor calibration. METHODS: A German-language web-based color vision test with 25 pseudoisochromatic color plates based on the color plates of Velhagen and Broschmann and of Ishihara was developed, which can be seen at http://www.farbsehtest.de. Volunteers were recruited by means of specific information distributed on the internet, in various print media, and on the radio. RESULTS: Over a period of 12 months, 2,126 of the initial volunteers [541 women and 1,588 men; mean age 34.27 (+/-14.1) years] with a valid test result for 25 color plates performed the web-based color vision test, 1,700 (506 women and 1,194 men) of whom passed it. Of the 426 volunteers who did not pass the test, 32 were women and 394, men. Counter-testing was performed on 101 volunteers (34 women and 67 men) with a mean age of 36.74 (+/-11.6) years. CONCLUSIONS: The results recorded in the patients who underwent counter-testing suggest that, if handled correctly, the web-based color vision test can be used as a color vision screening test on the internet.

Adolescent↗
PubMed2004

[Investigation of color vision using a web-based color vision test].

BACKGROUND: Screening tests of visual functions using the Internet are theoretically possible. To use these tests as a screening test, they must deliver comparable results with conventional test procedures. A web-based color vision test was developed based on pseudoisochromatic color plates. METHOD: The web-based color vision test was developed according to the pseudoisochromatic color plates by Velhagen and Broschmann using the programming-languages HTML, Java, and Perl. Sixty-five voluntary subjects, including nine color-deficient subjects, were examined by luminescence color plates (via web-based color vision test) and pigment color plates (via book). The statistical analysis was performed by determining the correspondence and the 95%-confidence interval. RESULTS: The correspondence of the test results for all subjects was 0.98 and the 95%-confidence interval was within 0.91 and 0.99. The correspondence of the test results in the group of color-deficient subjects was 1.0 and because of the limited number the 95%-confidence interval was within 0.71 and 1.0. CONCLUSIONS: The web-based color vision test with luminescence color plates for color-efficient and color-deficient subjects delivers test results comparable to pigment color plates under standardized examination conditions. Further studies are needed to examine if the web-based color vision test can also be used as an Internet screening test.

Adult↗
PubMed2003

Pretreatment with interleukin-2 modulates perioperative immunodysfunction in patients with renal cell carcinoma.

Complex perioperative immunodysfunction occurs in patients with renal cell carcinoma undergoing nephrectomy. Here, the effect of pretreatment with IL-2 is addressed. Of 63 patients who underwent tumour nephrectomy, 26 patients received four doses of 10 Mio IE/m2 IL-2 b.d. s.c. (i.e. a total of 40 Mio IE/m2) a week before operation, 37 did not. Parameters of cellular and humoral immunity (differential blood count, T-cell markers CD2, CD3, CD4, and CD8, B-cell markers CD19 and CD20, monocyte markers CD13 and CD14, NK-cell marker CD16, activation markers CD25, CD26, CD69 and HLA-DR, and cytokines IL-1-receptor antagonist (IL-1RA), IL-2, soluble IL-2-receptor (sIL-2R), IL-6, IL-10, and TGFbeta) were measured in peripheral venous blood. Blood was drawn before IL-2, one day before and immediately after the operation, and on the 1st, 3rd, 5th, and 10th postoperative day. All patients showed postoperatively elevated leukocyte and granulocyte counts, and elevated serum levels of cytokines IL-6 and IL-10. T-cell and activation markers were decreased. However, all these alterations were less accentuated in patients who had been pretreated with IL-2. Monocyte counts and IL-2 and TGFbeta levels were decreased, but IL-1RA and sIL-2R levels were elevated in pretreated patients. IL-2-related toxicity was WHO grade I-II in all patients, grade III in one patient. The anaesthetic regimen had no measurable effect. IL-6 concentrations were higher in renal venous than in venous pool blood, indicating IL-6 production in the tumour in vivo. Tumour-specific survival was better in pretreated patients with tumours extending beyond the kidney. Pretreatment with IL-2 modulates perioperative immunodysfunction in patients undergoing tumour nephrectomy. This affects in particular T-cell-mediated immunity and levels of cytokines IL-10 and IL-6. The IL-2 application scheme used here was followed by distinct counter regulation including monocytes, IL-2, sIL-2R, IL-1RA and TGFbeta. Taken together, pretreatment with IL-2 may complement surgery in the treatment of patients with renal cell carcinoma, and may help close the therapeutic gap between neo-adjuvant and adjuvant immunotherapy.

Adult↗
PubMed2001

Complex perioperative immuno-dysfunction in patients with renal cell carcinoma.

PURPOSE: Patients with renal cell carcinoma have an impaired function of the immune system, which is the basis for different approaches of immunotherapy. We address perioperative changes of several parameters of the immune system in these patients. MATERIALS AND METHODS: Parameters of cellular and humoral immunity, including differential blood count, T cell markers CD2, 3, 4 and 8, B cell markers CD19 and 20, monocyte markers CD13 and 14, natural killer cell marker CD16, activation markers CD25, CD26 and HLA-DR, and cytokines interleukin-1 (IL-1) receptor antagonist, IL-2, soluble IL-2 receptor, IL-6, IL-10 and transforming growth factor-beta, were measured in the venous blood of patients who underwent renal surgery extracorporeal shock wave lithotripsy (ESWL, Dornier Medical Systems, Inc., Marietta, Georgia). Patients were grouped and age matched, and 37 underwent tumor nephrectomy, 20 open renal surgery for nonmalignant reasons and 24 ESWL. A group consisting of 39 controls received no treatment. RESULTS: Little change was detected in controls and those patients who received ESWL. Patients who underwent open renal surgery had increased leukocyte and granulocyte counts until postoperative day 3 but had low T cell counts. The postoperative decrease in CD25 expressing cells corresponded to an increase in the soluble IL-2-receptor. Cytokines IL-6 and 10, which also have immunosuppressive properties, were markedly increased postoperatively. These changes were more noted (p <0.01) in those patients who underwent tumor nephrectomy than open renal surgery for nonmalignant reasons and remained detectable when paired patients with similar surgical trauma were compared. In tumor nephrectomy cases renal venous IL-6 was higher than peripheral venous levels. CONCLUSIONS: Patients with renal cell carcinoma suffer from selective immuno-dysfunction, indicating a rationale for perioperative immunomodulation.

Adult↗
PubMed2001

[Intraoperative oxygen consumption and organ function in liver transplantation].

Liver transplantation has become established as a reasonable and promising treatment option in terminal stages of liver diseases. Since there is no permanent artificial liver support available, primary "non-function" (PNF) of the graft is one of the most threatening complications. Therefore, an early and, if possible, intraoperative assessment of liver function is essential. Pathological changes in total oxygen consumption (VO2) are considered as an early indicator for the occurrence of PNF. Previously, PNF was analyzed using extensive calculations according to the Fick method, but since inauguration of the PhysioFlex anaesthesia device (Dräger, Lübeck, Germany), which is based on a closed anaesthesia circuit, continuous monitoring of oxygen consumption has become possible. The aim of the study was to investigate whether continuous VO2 monitoring using PhysioFlex allows immediate detection of pathological changes in graft function in the very early neohepatic phase of liver tranplantation. Therefore, 51 liver transplants were investigated at the University Hospital of Magdeburg with regard to a correlation between intraoperative VO2 values and ischaemic time periods of the donor organ and the postoperative liver function. A regular course of oxygen consumption was found in uncomplicated transplants and prompt liver function within normal ranges. PNF was not observed in any transplants. Changes in oxygen consumption were caused by early retransplants or by the delayed start of graft-based metabolism intraoperatively and transient diminished liver function found postoperatively, e.g., in pre-existing hepatorenal syndrome. In addition, VO2 indicated precisely the anhepatic and neohepatic phases during the course of liver transplantation. There was no correlation between the course of glucose content of the blood and the metabolic index of glucose and oxygen consumption or between both parameters and initial graft function. Furthermore, the duration of ischaemic time periods was not closely associated with oxygen consumption during the reperfusion phase. However, there was a correlation between intraoperative VO2 and postoperative bilirubin values, while a correlation between VO2 and GLDH as a further relevant parameter of postoperative graft function could not be confirmed, most likely because of the great variance in these values. In conclusion, the results suggest that changes in total oxygen consumption may, in part, be caused by changes in liver metabolism, depending on the various phases of liver transplantation. In addition, oxygen analysis allows monitoring of the critical phases of liver transplantation such as the anhepatic and early neohepatic periods with regard to immediate detection of early changes in graft metabolism. For routine use of this parameter, steady measurement of the mean value displayed on the PhysioFlex for selectable time periods would be helpful in addition to the continuous VO2 analysis, since there is a greater variance in the single VO2 values, which are documented by the anaesthesiologist, than in the online-detected and automatically calculated values of specific periods of transplantation.

Adolescent↗
PubMed2000

Reliability of symptom reports by healthy volunteers treated with placebo over several time periods.

In four test periods (medication-free control, three placebo periods with the suggestion randomised placebo or sedative or stimulant) 78 healthy medical students had to check off on a side-effect questionnaire those symptoms that they had experienced over the previous 72 h (adverse nondrug reactions). In the control period only 14 volunteers (18%) were without symptoms. In the course of 4 weeks this number doubled, and the number of symptoms complained decreased correspondingly, e.g. tiredness, headaches, muscle and joint pains etc. This development is relevant inasmuch as in phase-I studies the well-being of the volunteers is often monitored over protracted periods of time and perhaps decreasing interest or a decreasing motivation must be reckoned with. One or two rounds of tests present special situations, in any case, which cannot be reproduced. As the frequency of the symptoms complained of is modified by the personality structure, balanced groups must be formed for controlled studies. In Phase I trials it may sometimes be useful to characterize the volunteers psychologically.

Adult↗
PubMed1999

[Contrast enhancement in the public environment--improvement in orienting capacity of visually handicapped patients].

BACKGROUND: Partially sighted often experience problems in orientation in public areas. Individual visual aids can only be used with limitations. Improving light intensity and colour contrasts of timetables, information signs, direction symbols, etc. can provide remedies. Experimentally substantiated directives do not yet exist. PATIENTS AND METHODS: Experiments were conducted in 231 partially sighted subjects (binocular vision < 0.3) diagnosed as experiencing dullness when watching the media, having maculopathies, glaucomas, or dystrophic alterations of the retina or choroid, and in 43 normal subjects to determine the subjective assessment of colour and light-intensity contrasts. The presented contrast patterns were Hartmann-characters as infield (3.3 degrees) with a rectangular surround (19.5 degrees x 14.3 degrees). Three experimental series were carried out in which subjects assigned 14 non-coloured/non-coloured contrasts, 35 non-coloured/colour contrasts and 30 colour/colour contrasts to any of the five assessment classes of extremely poor, poor, optimal, sharp, extremely sharp. The colour contrasts consisted of combinations of yellow, green, red, purple, blue, and non-coloured. RESULTS: For non-coloured/non-coloured, the subjects preferred positive contrasts (bright infield, dark surround). Preferred contrast levels were 0.91 to 0.99 for positive contrasts and -0.96 to -0.99 for negative contrasts. For colour/non-coloured contrasts, 90% of the partially sighted preferred yellow as the foreground colour with a contrast level above 0.89. For colour/colour contrasts, optimal assessments of 90% of all partially sighted were yellow/purple and yellow/blue with contrast levels above 0.90. The determined results are applicable for the exact experimental contrast settings only. A field manual was prepared for planning and design of contrasts suited for the partially sighted in public areas. CONCLUSIONS: Partially sighted, in subjective contrasts assessment, prefer bright characters of signs on a dark background for both non-coloured and colour contrasts with contrast levels above 0.9. Yellow was the preferred infield colour.

Adolescent↗
PubMed1999

The antipruritic effect of a 5-HT3 receptor antagonist (tropisetron) is dependent on mast cell depletion--an experimental study.

The background of this study is that 5-HT3 receptor antagonists are reported to have an antipruritic effect in uremic and cholestatic pruritus. Recently, we could not confirm such an effect in healthy subjects under experimental conditions. Therefore, it was the aim of the present study to further evaluate a possible antipruritic effect of a 5-HT3 receptor antagonist (tropisetron) on serotonin- and histamine-induced itch before and after skin mast cell depletion in 10 healthy subjects. The results were compared to serotonin and histamine iontophoresis in non-pretreated and pretreated skin with an orally applied antihistamine (cetirizine). Skin mast cell depletion was performed by iontophoretical application of compound 48/80. Wheals and flares were planimetrically evaluated. Itching and burning sensations were rated on an analog scale over a 24-min period. The test protocol also comprised alloknesis, defined as induction of perifocal itch sensations by a mechanical stimulus. When serotonin was iontophoretically applied after mast cells had been depleted before, oral tropisetron resulted not only in significantly lower whealing, itching and alloknesis but also reduced flares. In contrast, after oral pretreatment with tropisetron histamine-induced reactions before and after mast cell depletion did not significantly change. Our study demonstrates that in this model, tropisetron as a 5-HT3 receptor antagonist does not effect histamine-induced itch but has a measurable effect in serotonin-induced reactions when mast cells were depleted before. From these data evidence now exists why tropisetron is to some extent effective in certain types of pruritus such as uremic pruritus, known for increased histamine liberation and increased serotonin levels as well as degranulated and diffusely spread mast cells in the skin.

Adult↗
PubMed1999

[Laparoscopic cholecystectomy. A recommendable indication in acute cholecystitis?].

While laparoscopic cholecystectomy has become the procedure of choice for the elective treatment of symptomatic cholecystolithiasis the question whether patients with acute cholecystitis should be operated laparoscopically or conventionally is still debated. Nevertheless, more and more surgeons tend to use the laparoscopic approach even in patients with acute cholecystitis. Of 1006 laparoscopic cholecystectomies performed at our hospital 42 were done for acute cholecystitis. Conversion to an open procedure was necessary in only one patient because of severe inflammatory changes. The overall mortality was zero. The average age was 45.9 years for all patients and 50.4 years for those with acute cholecystitis. The average operating time in patients with acute cholecystitis was 81 minutes compared to 62 minutes in patients who underwent elective laparoscopic cholecystectomy. The complication rate and the average hospitalization time did not differ significantly between the two groups. Our own data as well as the data retrieved from the literature seem to indicate that laparoscopic cholecystectomy is superior to the open procedure in the treatment of acute cholecystitis. Prerequisite is that the operation is performed less than 72 hours after the onset of the symptoms by an experienced operating team and the readiness to convert to open procedure if necessary. Under those circumstances laparoscopic cholecystectomy seems to be the treatment of choice for acute cholecystitis.

Acute Disease↗
PubMed1998

Correlation of DNA content and nucleomorphometric features with World Health Organization grading of meningiomas.

Many studies dealing with extracranial cancer showed a strong correlation of DNA ploidy to a poor clinical outcome, recurrence, or malignancy. In brain tumors, analysis of DNA content did not always provided significant diagnostic information. In this study, DNA density and karyometric parameters of 50 meningiomas (26 Grade I, 10 Grade II, 14 Grade III) were quantitatively evaluated by digital cell image analyses of Feulgen-stained nuclei. In particular, the densitometric parameter SEXT, which describes nuclear DNA content, as well as the morphometric values LENG (a computer-assisted measurement of nuclear circumference), AREA (a computer-assisted measurement of nuclear area), FCON (a parameter that describes nuclear roundness), and CONC (a describing nuclear contour), evaluated with the software IMAGE C, were correlated to World Health Organization (WHO) grading using univariate and multivariate methods. AREA and LENG values showed significant differences between tumors of Grades I and III. FCON values were unable to distinguish WHO Grade III from Grade I/II but were useful in clearly separating Grade II from Grade I tumors. CONC values detected differences between WHO Grades II and I/III tumors but not between the latter. SEXT values clearly distinguished Grade III from Grade I/II tumors. The 1c, 2c, 2.5c, and 5c exceeding rates showed no predictive values. Only the 6c exceeding rate showed a significant difference between Grades I and III. These results outline the characteristic features of the atypical (Grade II) meningiomas, which make them a recognizable tumor entity distinct from benign and anaplastic meningiomas. The combination of DNA densitometric and morphometric findings seems to be a powerful addition to the histopathologic classification of meningiomas, as suggested by the WHO.

Cell Nucleus↗
PubMed1996

Adverse nondrug reactions: an update.

OBJECTIVE: Healthy volunteers are involved in stage I of clinical investigations. It appears to be necessary to characterize such subjects more closely. Representing an essential aspect are symptoms giving rise to complaints that are typical side effects of drugs but that often also occur as adverse nondrug reactions. Correlations are supposed to exist between personality, motivation, and emotion of subjects and the incidence of their complaints. METHODS: One hundred thirty medical students answered the "Questionnaire for Side Effects of Drugs" (Reidenberg and Löwenthal, 1968), and they were studied with regard to their personality (Freiburg Personality Inventory), motivation (Motivation Q-Sort) and emotion (State-Trait-Anxiety Inventory). RESULTS: The most frequent complaints noted in young healthy volunteers who did not take any drugs were fatigue (65%), headache (25%), and nasal congestions (30%). Only 11% of the medical students were free of symptoms, 50% stated that they had one or two symptoms, and 3% had more than six symptoms. Statistically significant, even though weak, correlations existed between the number of symptoms and the personality traits of nervousness and neuroticism, motivation, and trait-anxiety. However, cluster analysis was adopted to form two groups: One subgroup (not nervous, emotionally stable, success-motivated, and not very anxious) that stated less adverse nondrug reactions, and another contrasting subgroup that complained about symptoms more frequently. CONCLUSION: It appears that the distribution of the incidence of complaints in a nonselected group of healthy volunteers is not of a random character. The relevance of this finding to stage I clinical trials is evident.

Adult↗
PubMed1996

[Subjective contrast evaluation by visually handicapped patients].

Personal optical and electronic devices are helpful to people with binocular vision of less than 0.3 or a substantially impaired visual field. Striking brightness and color contrast may help patients to orient themselves outdoors. This is particularly true for patients with age-related macular degeneration who have diminished contrast sensitivity as evaluated by the Vistech test and the low-contrast sensitivity test. In this study, the desired level or color combination of contrasts was assessed subjectively by a scaled estimate. The patients were required to assess a sample of 79 black-and-white and color contrasts according to a five-point scale comprising the ratings "much too low", "low", "optimal", "high", "much too high". The visual fields (outfield, infield) were either colorless or contained the colors yellow, green, red, purple or blue. The study involved 59 patients with age-related macular degeneration. Ninety percent of the patients were over 65 years old. There were twice as many women as men. The control group population consisted of 43 emmetropic subjects. In black or white infields on a colorless background (light gray to dark gray), a slight preference for positive (infield lighter than the background) contrast situations was found. The optimal contrasts were in the range of [K[ > 0.91. When colored infields were presented on a colorless background, the light infield colors yellow and green were preferred. The optimal contrast level was found to be [K[ > 0.85. Similarly, when colorless and colored infields were presented, light infield colors (white, yellow, green) on a dark background (purple, blue) were preferred. In selecting contrasts, subjects with impaired vision because of age-related macular degeneration preferred positive contrasts, i.e., mainly white, yellow and green on a colored or colorless background. These results provide information that can be used in designing orientation aids, e.g., road striping and lines, edges of stairs, handrails, timetables, etc. Conflicts of interest with emmetropic subjects is not to be expected. Subjects in the control group, while preferring similar contrasts, were ready to accept a wider range than the partially sighted.

Aged↗
PubMed1995

The healthy volunteer in clinical pharmacology: personality and motivation.

The aim of the present study was to quantify the personality structure and motivation of medical students, who are often the most readily available source of healthy volunteers, since it has long been known that the pharmacodynamics and pharmacokinetics of drugs can be substantially modified by predominant personality traits (e.g. neuroticism, extraversion). Over the course of 4 years, a total of 337 subjects (165 males, 172 females) out of the 496 medical students asked, participated in the study after appropriate instruction. Students were tested using the Motivation Q-Sort method which, by means of questions ("questionnaire sort"), investigates whether a subject tends to react in a success-motivated (SM) or a failure-motivated (FM) mode. The variable measured is the so-called net hope (NH), where NH > 1.6 corresponds to SM and NH < -0.3 corresponds to FM. We also used the Freiburg Personality Inventory (FPI) as a suitable method of determining personality structure. The predominant traits of interest found were nervousness (FPI 1), extraversion (FPI E), and neuroticism (FPI N). In the first series of tests (primary selection), motivation only was determined in 337 volunteers. The range was fairly broad, with NH values from 4.32 (highly SM) to -3.09 (highly FM). In the second series of tests, about 60 SM and 60 FM subjects were selected. The Motivation Q-Sort method was repeated with students placed under more difficult conditions, and the FPI was also performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

[Presentation of multidimensional observed vectors in the form of trigonometric functions, explained by means of an example from internal medicine].

In the present paper a method of the graphic representation of multivariate data is described which depicts the vectors of the measuring values in form of trigonometric functions. The usefulness of this form of representation is demonstrated with the help of a material of medical data from the field of diseases of the thyroid gland. Here a comparison with the representation of multidimensional vectors of the observed values in form of graphs or in form of transformation into the plane emphasizes the good perceptibility of particularities of the data.

Data Display↗
PubMed1980

[A graphic representation of multivariate data].

In the present paper three methods of the graphic representation of multivariate data are described. One method represents the multivariate vectors of the measuring value in form of graphs, whereas the two other methods are based on transformations into the plane and produce point diagrams. The efficacy of the representation methods is demonstrated with the help of a material of medical data from the field of diseases of the thyroid gland.

Data Display↗