Biomedical subjects

M Grumann

Publications and source records attributed to M Grumann.

6 recordsLinked to original sources

PubMed2006

Fully integrated whole blood testing by real-time absorption measurement on a centrifugal platform.

We present a novel microfluidic concept to enable a fast colorimetric alcohol assay from a single droplet of whole blood. The reduced turn-around time of 150 seconds is, on the one hand, achieved by a full process integration including metering, mixing with reagents, and sedimentation of cellular constituents. On the other hand, our novel total internal reflection (TIR) scheme allows to monitor the increase of the absorbance values in real-time. Thus, the saturation values can be predicted accurately based on an extrapolation of real-time measurements acquired during a 100 second initial period of rotation. Additionally, we present a metering structure to define nanolitre sample volumes at a coefficient of variation (CV) below 5%.

Blood Chemical Analysis↗

PubMed2006

Sensitivity enhancement for colorimetric glucose assays on whole blood by on-chip beam-guidance.

In this paper, we present a novel concept for optical beam-guidance to significantly enhance the sensitivity of colorimetric assays by extending the optical path length through the detection cell which linearly impacts the resulting attenuation of a probe beam according to the law of Beer-Lambert. In our setup, the incident probe beam is deflected by 90( composite function) into the chip plane at monolithically integrated V-grooves to pass a flat detection cell at its full width (i.e., with a path length of 10 mm) instead of its usually much smaller height. Afterwards, the attenuated beam is redirected by another V-groove towards an external detector. The general beam-guidance concept is demonstrated by a glucose assay on human whole blood on a centrifugal microfluidic "lab-on-a-disk" platform made of COC. We achieve an excellent linearity with a correlation coefficient (R (2)) of 0.997 paired with a lower limit of detection (200 microM) and a good reproducibility with a coefficient of variation (CV) of 4.0% over nearly three orders of magnitude. With an accelerated sedimentation of cellular constituents by centrifugal forces, the sample of whole blood can be analyzed in a fully integrated fashion within 210 s. This time-to-result can even be improved by the numerical extrapolation of the saturation value. Additionally, the direct assay on whole blood also shows a negligible correlation with the hematocrit of the blood sample.

Blood Chemical Analysis↗

PubMed2005

Batch-mode mixing on centrifugal microfluidic platforms.

We present two novel fluidic concepts to drastically accelerate the process of mixing in batch-mode (stopped-flow) on centrifugal microfluidic platforms. The core of our simple and robust setup exhibits a microstructured disk with a round mixing chamber rotating on a macroscopic drive unit. In the first approach, magnetic beads which are prefilled into the mixing chamber are periodically deflected by a set of permanent magnets equidistantly aligned at spatially fixed positions in the lab-frame. Their radial positions alternatingly deviate by a slight positive and negative offset from the mean orbit of the chamber to periodically deflect the beads inbound and outbound during rotation. Advection is induced by the relative motion of the beads with respect to the liquid which results from the magnetic and centrifugal forces, as well as inertia. In a second approach--without magnetic beads--the disk is spun upon periodic changes in the sense of rotation. This way, inertia effects induce stirring of the liquids. As a result, both strategies accelerate mixing from about 7 minutes for mere diffusion to less than five seconds. Combining both effects, an ultimate mixing time of less than one second could be achieved.

Centrifugation↗

PubMed2001

Assessment of quality of life in cancer patients: complexity, criticism, challenges.

Over the past two decades, quality of life (QoL) research has become an integral endpoint in clinical trials, yet, regarding its implementation in daily clinical work, much hesitation still abounds. This article discusses how complex psychological processes at work within a patient along with environmental factors act upon each other to form what is finally measured in a QoL score. An extended model of QoL is suggested which comprehensively describes the contribution of factors such as common psychological reactions to cancer, coping mechanisms, traits, and socioeconomic conditions to the final outcome in a QoL inventory. In order to avoid disappointment at the utility of results gained in QoL assessment both in clinical trials and daily routine, the choice of appropriate QoL instruments, their goal-directed implementation, and suitable expectations towards the anticipated aims are pivotal aspects to be ensured. Competent utilization of QoL assessment contributes to an enhanced standard of patient-centered care in oncology.

Adaptation, Psychological↗

PubMed1992

Influence of various nutrients and their mode of application on plasma cholecystokinin (CCK) bioactivity.

CCK is known to be a major endocrine stimulant of the exocrine pancreas. However, the influence of various compositions of nutrients and their mode of administration on plasma CCK is still not clear. We therefore studied plasma CCK after either oral or intraduodenal administration of various solid and liquid diets. Plasma CCK was measured by bioassay. Nine healthy male volunteers received three different isocaloric diets via intraduodenal perfusion (1 kcal/ml; 300 ml/90 min). Diet A consisted of low-molecular oligopeptides (energy: protein 18%, fat 22%, carbohydrates 60%); diet B was a high molecular diet enriched with fat and fiber (protein 15%, fat 30%, carbohydrates 55%, fiber 1 g/100 ml); and diet C was a high molecular diet, poor in fat and fiber-free (protein 14%, fat 7%, carbohydrates 79%). All diets caused a rapid increase in plasma CCK, followed by a slow decrease. The highest CCK plasma values were achieved with diet B (8.4 +/- 1.6 pM); diets A and C led to similar, rather low plasma CCK values (A: 5.0 +/- 0.7 pM). Another five volunteers received the above-described liquid diets orally. Integrated CCK plasma values were similar for all oral liquid diets studied and not different from those seen after intraduodenal administration of the high-molecular high-fat diet B. Oral administration of a solid diet (ten volunteers) comparable to diet B in calories and nutrient composition caused a rather small and delayed increase in plasma CCK.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Sexual functioning in patients following radical hysterectomy for stage IB cancer of the cervix.

Despite extensive research on sexual dysfunction after gynecological cancer, uncertainty remains regarding the nature and extent of sexual problems following surgery for early cervical cancer. This study investigated whether radical hysterectomy for stage IB cancer of the cervix without adjuvant treatment entails short- or long-term sexual difficulties. Twenty patients with stage IB cervical cancer undergoing radical hysterectomy (CG), 18 women treated with hysterectomy for a benign gynecological condition (BG), and 20 gynecologically healthy women (HG) were studied. At 0, 4, and 8 months postoperatively, data were prospectively gathered using standardized questionnaires and specifically developed scales. Sexual functioning was covered in 15 specifically designed items and analyzed using Fisher's exact tests. For all other variables, group comparisons were computed using analysis of variance (ANOVA) or nonparametric statistical equivalents. Nonsignificant trends, consistent across time and groups, resulted for most of the sexual variables. Preoperatively, cancer patients exhibited slightly better sexual functioning than the other two groups, but over time this decreased slightly. Conversely, sexual functioning among the patients with benign disease showed steady improvement. These results indicate that radical hysterectomy for stage IB cervical cancer does not entail major sexual sequelae. Because of the limited sample size of our study, conclusions must be drawn cautiously.

Adult↗