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Biomedical subjects

C Fuchs

Publications and source records attributed to C Fuchs.

189 records · Page 11Linked to original sources
PubMedDate not supplied

Capacitance in ant cuticle is frequency dependent: a statistical model.

The capacitance and the electric resistance of the cuticle of the ant Cataglyphis bicolor nigra Andr é (Hymenoptera, Formicinae ) were measured. The measurements were done at the frequencies 100 Hz and 1000 Hz and at a temperature range of 27.5-45 degrees C. Inverse correlation was observed between the capacitance and the frequency, so that at the higher frequency the capacitance was lower. Thus, in some instances, at 1000 Hz the capacitance ranged between 0.49 and 2. 16nF , while at 100 Hz it ranged between 5.74 and 19. 39nF at the measured temperature range. A similar inverse correlation was detected also between the resistance and the frequency. At 1000 Hz, the resistance values in some specimens ranged between 0.166 and 0.278 M omega whereas at 100 Hz they varied between 0.342 and 0.883 M omega. At both frequencies measured there was a temperature-dependence of the capacitance and of the electric resistance. With increase in temperature there was increase in the capacitance and a decrease in the resistance. Invariably, the trend of cuticular behavior was similar under cooling as under warming, but the values differed, creating a gap (hysteresis). Under cooling the resistance values were higher and the reverse was true for the capacitance. A statistical model is offered which graphically describes the behavior of the ant cuticle (resistance and capacitance) under changes in temperature and frequency. X-ray analysis of the cuticle revealed the presence of Ca as the most prominent element. Additional elements, but less prominent were P, S and K. It also contains Fe and Zn. The finding of a correlation between the capacitance and the frequency might lead to the following conclusions: that the measured system contains polarized substances; that the measured value in each case represents a resultant of values obtained from the measurement of more than one electrical circle (and probably more than one network of electrical circles); and that possibly a combination of (a) and (b) prevails. Presumably these changes in the capacitance and resistance at different temperatures and frequencies indicate that the ant cuticle is capable of responding to changes in the physical ambience , thus promoting proper ant spatial orientation and the pursuant behavior.

Animals↗
PubMedDate not supplied

Stable, long-term bacterial production of soluble, dimeric, disulfide-bonded protein pharmaceuticals without antibiotic selection.

Numerous biopharmaceuticals and other recombinant biotechnology products are made in prokaryotic hosts. However, bacterial production of native, biologically active eukaryotic proteins is rarely possible for disulfide-bonded and/or multisubunit proteins. We previously described the production of soluble, native disulfide-bonded dimeric proteins in the Escherichia coli cytoplasm (Miele et al., 1990; Mantile et al., 1993). Native, biologically active proteins with up to six disulfide bonds have been produced with our expression system (Garces et al., 1997). However, plasmid instability during induction limited its usefulness. We now report the stable, high-level expression of soluble, disulfide-bonded human uteroglobin without antibiotic selection. We designed a new vector containing a multifunctional stabilization region that confers complete plasmid stability and increased protein yields without copy number increases. Recombinant expression remains fully inducible after long-term continuous culture in nonselective liquid medium (at least 260 generations). This system may significantly expand the applications of bacterial expression to recombinant production of soluble, bioactive proteins for biochemical studies and biopharmaceutical/industrial purposes. As a result of the very broad activity spectrum of the stabilization region we selected, its use could be extended to bacterial hosts other than enterobacteria.

Anti-Bacterial Agents↗
PubMedDate not supplied

The eustachian tube muscles in otitis media. A comparison between eustachian tube muscles in healthy and inflamed ears.

The cross-sectional area of the tensor palati (TP) and levator palati (LP) muscles in the mid-portion of the Eustachian tube was measured in serially sectioned histological specimens of 35 temporal bones (TB). 17 of the TBs presented acute or secretory otitis media. The other 18 TBs showed no evidence of inflammatory disease. No significant differences were found between the mean sizes of the muscles coming from TBs with acute and secretory otitis media and of those from TBs without signs of inflammation. The cross-sectional area of the LP was found to be significantly larger than that of the TP. These results raise the question as to the actual role of the muscles' size in inflammatory middle ear disease in infants and children, and as to the role of the LP.

Acute Disease↗
PubMedDate not supplied

Comparison of the sensitivity of different diagnostic tests for pancreatitis in cats.

The objective of this study was to compare the sensitivity of different diagnostic tests for pancreatitis in cats. Twenty-one cats with confirmed pancreatitis were evaluated at the Small Animal Clinic of the School of Veterinary Medicine in Hannover, Germany, between September 1997 and January 1999. Clinical signs of affected cats were nonspecific, with 95% of the cats showing anorexia and 86% lethargy. Also, hematologic and biochemical abnormalities of affected cats were nonspecific. Serum feline trypsin-like immunoreactivity (fTLI) in these 21 cats with pancreatitis was 127.5 +/- 109.5 microg/L (mean +/- SD; range, 24-500 microg/L). Fourteen of the 21 cats with pancreatitis had complicating conditions. Their serum fTLI was 153.9 +/- 124.3 microg/L (mean +/- SD; range, 29 500 microg/L). In this study, abdominal ultrasound showed a sensitivity for pancreatitis of 24%, and abdominal computed tomography had a sensitivity of 20%. Serum fTLI had a sensitivity between 86% when a cut-off value of 49 microg/L was used (upper limit of the control range) and 33% when a cut-off value of 100 microg/L was used. We conclude that in this group of cats with pancreatitis, measurement of serum fTLI was the most sensitive diagnostic test of those evaluated. Abdominal ultrasound, however, may be a valuable diagnostic tool in some cats with pancreatitis.

Animals↗
PubMedDate not supplied

Divalent ions and myocardial function during cardiopulmonary by-pass (CPB). Changes of total calcium, ionized calcium, and magnesium in plasma.

In 17 patients who underwent openheart surgery with cardiopulmonary bypass using heparinized fresh blood for priming the heart-lung machine the following investigations were done: Blood samples taken at different periods of surgery were assayed for total calcium (Catot), ionized calcium (Ca++), magnesium (Mg), hemoglobin, total pasma proteins, and the acid-base-status. Considering the different kinds of cardiopulmonary bypass the patients were divided into three groups: In the first group the results ofsurgical procedure with and without hemodilution perfusion were compared. During hemodilution perfusion Catot decreased markedly whereas Ca++ remained nearly constant. In the second group the influence of different calcium concentrations of the prime solution on Catot and Ca was tested. A low calcium content of 2.8 mEq/1 lowered Catot and Ca++ to subnormal levels. In the third group results of Mg-induced cardioplegia were compared with findings during surgical procedure with anoxic cardiac arrest. A remarkable increase of magnesium at the perfusion onset could be observed. Magnesium remained within the upper level of normal range until surgery end and decreased to normal values in the postoperative stage. Since energy requirements of the arrested heart and thus the velocity of ATP-breakdown during ischemia are closely related to the Ca++ concentration of the extracellular space low plasma calcium levels are considered to be advantageous during cardiopulmonary bypass. Only at the end of partial bypass before the heart fully takes over circulating work a sufficient calcium substitution is recommended.

Adolescent↗