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Biomedical subjects

M Kropp

Publications and source records attributed to M Kropp.

7 recordsLinked to original sources
PubMed2006

Surgery for right-sided colonic diverticulitis: results of a 10-year-observation period.

INTRODUCTION: In contrast to sigmoid diverticular disease, right colonic diverticulitis is a rare disease in Western countries. The clinical presentation is often similar to acute appendicitis. OBJECTIVE: The aim of this study was to analyze surgical challenge in right-sided diverticulitis. MATERIALS AND METHODS: All patients who underwent resection for both right-sided and sigmoid diverticular disease were registered prospectively in a database (observation period, 1996-2005). A retrospective analysis of all patients who underwent resection for right-sided colonic diverticulitis (ileocolic resection, right colectomy) was performed. Special focus was set on incidence, clinical symptoms, indication, procedure, clinical outcome, and histopathologic findings including immunohistochemistry. RESULTS: From a total of 593 patients treated surgically for recurring or acute complicated diverticular disease, the majority (97.8%) suffered from sigmoid diverticulitis (n = 580), whereas 2.2% (n = 16) underwent surgery for right-sided diverticulitis (including three patients with combined sigmoid and cecal diverticulitis). Related to the total number of appendectomies (n = 1167), this represented an incidence of 1.4%. In five of 16 patients, acute appendicitis was presumed preoperatively. Most common diagnostic was ultrasonography. In the group of patients with right-sided diverticulitis, the most common procedure was right hemicolectomy (n = 10), followed by ileocolic resection (n = 3) and combined right colonic resection with sigmoid resection (n = 3). Histopathological investigation confirmed complicated diverticulitis of the cecum with local perforation or abscess in 75% of the patients (12/16). Hypoganglionosis or aganglionosis was diagnosed in seven of the 16 resected specimens. DISCUSSION: As right-sided diverticulitis is a rare colonic disease in Western countries, the differentiation from acute appendicitis may be difficult. In general, there is no difference in the treatment of right-sided diverticulitis compared to left-sided diverticulitis. As most cases will remain clinically unimminent, surgery is only indicated in complicated right-sided cases. Resection of the inflamed colonic segment with primary anastomosis is safe and can be performed laparoscopically. It can only be speculated whether hypoganglionosis or aganglionosis is a causative factor in the etiology of right-sided diverticulitis.

Adult↗
PubMed2005

Differential coding of humoral stimuli by timing and amplitude of intracellular calcium spike trains.

The ubiquitous Ca2(+)-phosphoinositide pathway transduces extracellular signals to cellular effectors. Using a mathematical model, we simulated intracellular Ca2+ fluctuations in hepatocytes upon humoral stimulation. We estimated the information encoded about random humoral stimuli in these Ca2+ spike trains using an information-theoretic approach based on stimulus estimation methods. We demonstrate accurate transfer of information about random humoral signals with low temporal cutoff frequencies. In contrast, our results suggest that high-frequency stimuli are poorly transduced by the transmembrane machinery. We found that humoral signals are encoded in both the timing and amplitude of intracellular Ca2+ spikes. The information transmitted per spike is similar to that of sensory neuronal systems, in spite of several orders of magnitude difference in firing rate.

Action Potentials↗
PubMed2001

Humoral coding and decoding.

Humoral communication systems are dynamically regulated. Most hormones are released in a pulsatile or burst-like manner into the bloodstream. It is well known that information coded in the frequency and amplitude of secretory pulses allows for the differential regulation of specific target cell function and structure. However, despite intensive study of transmembrane signalling relatively little is known about how the temporal dynamics of extracellular humoral stimuli specifically regulates the temporal pattern of intracellular signalling pathways, such as Ca2+-dependent signalling. Repetitive spikes of Ca2+ encode this information in their amplitude, duration and frequency, and are in turn decoded into the pattern of gene expression and phosphorylation of target proteins. Using a mathematical model for G protein-coupled Ca2+ signalling and information-theoretic approaches to stimulus reconstruction we have systematically quantified the amount of information coded in the Ca2+-signal about the dynamics of the stimulus, which allows us to explore the temporal bandwidth of transmembrane signalling. These in silico approaches permit us to differentiate the amount of information coded in the frequency, temporal precision, amplitude and the complete Ca2+-signal. This may open an avenue to the quantification of information flow and processing in the intra- and intercellular coding and decoding machinery.

Action Potentials↗
PubMed1996

Thoracic disc.

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Aged↗
PubMed1990

["Modality shift" paradigms and subjective basic symptoms in schizophrenic patients with various developmental biological risk anamnesis].

Clinical experimental research on schizophrenia does not consider maturation processes of brain function in the majority of cases. In the course of neuronal organization and the differentiation phases of cerebral systems, early traumas in functionally important regions of the brain are accompanied by a facultative impairment of complex systems of information processing. Against the background of the comprehensively coherent "integrative psychobiological model of schizophrenia" (Ciompi) with high construct validity, (experimental) psychology investigations are reported on in the context of the "high-risk" concept in 44 young (20-37 years old) and mainly chronic schizophrenic patients with formation of a specific hypothesis for the developmental biology of the condition. In two homogeneous groups with the same structure, it is checked whether a discriminative appraisal concerning a different organization principle of central information processing systems is possible with "crossmodal" choice-reaction times (cCRT) and certain subscales of the Frankfurt symptom questionnaire (FBF) with regard to alternatively distributed and specially operationalized anamnestic biological risk factors. It can be objectively established in terms of experimental psychology that postpsychotically de-actualized "risk-free" schizophrenics differ from the reference group with a high-risk anamnesis in terms of significantly prolonged cCRT, but not from healthy subjects and an "MBD" control group. In addition, the FBF subscores "weakness of selective attention" and "loss of automatized skills" correlate with poor cCRT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

[The hypnotic effect of the new benzodiazepine derivative lormetazepam when given intravenously (author's transl)].

1. 7 groups of 3 healthy male volunteers each, at the age of 21--27 years received various doses of Lormetazepam (0.0635 to 4.0 mg/70 kg). -- 2. The drug was injected intravenously during 60 s. Before, during and up to 4 hours after the injections the EEG, eye-movements, ECG and respiration was recorded and blood pressures measured at given time intervals. -- 3. The vigilo-somnograms showed after the injections a change in the EEG-stages, indicating a reduction of alertness, transitions into reduced wakefulness or beginning stages of sleep. Corresponding to clinical signs one can speak with i.v. applied doses of 0.0635 to 0.5 mg/70 kg of tranquilizing, with 1 mg/70 kg of sedative and with 2--4 kg of hypnotic effects. There has been a good dosage-efficiency relation. -- 4. Side-effects or unwarranted symptoms have not been seen during the clinical observations.

Adult↗