Biomedical subjects

C Stolz

Publications and source records attributed to C Stolz.

At least 19 recordsLinked to original sources

PubMed2003

Growth and cellular differentiation: a physico-biochemical conundrum? The example of the hand.

Currently, the predominant hypothesis explains cellular differentiation as an essentially genetic intracellular process. The goal of this paper is to suggest that cell growth and differentiation may be, simply, the result of physical and chemical constraints. Bone growth occurs at the level of cartilage conjunction (growth plate) in a zone of lesser constrain. It appears that this growth also induces muscle, tendon, nerve and skin elongation. This cartilage growth by itself seems to explain the elongation of the hand. Growth stops at puberty likely because of feed-back from an increasing muscle load. The ossification (that is differentiation of cartilage into bone) appears to result from the shear stress induced. The study of bone age, obtained by X-ray picture of the hand, shows that ossification of epiphyses is very precise both in time and space. Computer modelization suggests that this ossification occurs where shear stress is greatest. The cartilage which does not ossify (joint, nose, larynx, ear, bronchus, etc.) is not exposed to high shear. Shear stress induces the secretion of extracellular matrix and a change of the biochemical environment of the cell. Precipitation of calcium phosphate, as in ossification, seems related to the alkalosis induced by shear stress. To speak in more general terms, loss of cellular differentiation, as occurs with cancer, can result from a change in the physical-chemical environments.

Alkalosis↗

PubMed2002

Safety and pharmacokinetics of p792, a new blood-pool agent: results of clinical testing in nonpatient volunteers.

RATIONALE AND OBJECTIVES: To evaluate the safety and pharmacokinetics of P792, a new macromolecular blood-pool agent for magnetic resonance imaging (MRI), in nonpatient volunteers. METHODS: This was a single blind, placebo-controlled, ascending-dose study in 32 healthy male volunteers, randomized to receive a single intravenous dose of P792 (0.0065, 0.013, 0.026, and 0.039 mmol/kg). The safety controls consisted of complete pre- and postdose physical examinations, measurement of vital signs, clinical laboratory investigations, and monitoring of adverse events (up to 22 days after injection). For pharmacokinetic analysis, the determination of P792 was performed using the ICP-MS technique for blood and urine samples up to 22 days. RESULTS: No serious adverse events occurred during the study. There were no clinically significant changes in vital signs, or clinical laboratory findings. P792 blood half-life, distribution volume, and renal clearance are consistent with the definition of a rapid clearance blood-pool agent (RCBPA) as defined previously. CONCLUSION: P792 appeared to be a safe and well-tolerated RCBPA in nonpatient subjects. Phase II studies will be conducted to evaluate the efficacy of the blood-pool agent for vascular, perfusion, and permeability imaging in MRI.

Analysis of Variance↗

PubMed1994

The effect of valerian extract on sleep polygraphy in poor sleepers: a pilot study.

The effect of acute and repeated treatment (seven days) with a valerian extract (Valdispert forte, 405 mg t.i.d.) on objective and subjective measures of sleep was studied. Polysomnography was conducted in 14 elderly poor sleepers on three nights, at one-week intervals (N0, N1, N2). N0 was an adaptation night, N1 and N2 the first and last night under treatment. Six subjects received placebo and eight subjects valerian. Subjects in the valerian group showed an increase in slow-wave sleep (SWS) and a decrease in sleep stage 1. Density of K-complexes was increased under active treatment. There was no effect on sleep onset time or time awake after sleep onset. REM sleep was unaltered. There was also no effect on self-rated sleep quality. We hypothesize that valerian increases SWS in subjects with low baseline values.

Aged↗

PubMed1989