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Biomedical subjects

L Menzel

Publications and source records attributed to L Menzel.

10 recordsLinked to original sources
PubMed2001

Dicynthaurin: an antimicrobial peptide from hemocytes of the solitary tunicate, Halocynthia aurantium.

We isolated a novel antimicrobial peptide, dicynthaurin, from hemocytes of a tunicate, Halocynthia aurantium. The native peptide had a mass of approximately 6.2 kDa and was composed of two 30-residue monomers without sequence homology to any previously identified peptides (ILQKAVLDCLKAAGSSLSKAAITAIYNKIT). Most cynthaurin molecules were C-terminally amidated and were linked covalently by a single cystine disulfide bond. When performed in membrane-mimetic environments, circular dichroism studies of dicynthaurin revealed largely alpha-helical conformations. Dicynthaurin's broad-spectrum activity encompassed Gram-positive (Micrococcus luteus, Staphylococcus aureus, Listeria monocytogenes) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), but not Candida albicans, a fungus. Although dicynthaurin was purified from a marine invertebrate, its antimicrobial activity was optimal at NaCl concentrations below 100 mM. This suggests that the antimicrobial actions of this molecule may take place intracellularly (e.g., within a phagosome) rather than extracellularly.

Amino Acid Sequence↗
PubMed2001

Spectroscopic detection of biological NO with a quantum cascade laser.

Two configurations of a continuous wave quantum cascade distributed feedback laser-based gas sensor for the detection of NO at a parts per billion (ppb) concentration level, typical of biomedical applications, have been investigated. The laser was operated at liquid nitrogen temperature near lambda = 5.2 microns. In the first configuration, a 100 m optical path length multi-pass cell was employed to enhance the NO absorption. In the second configuration, a technique based on cavity-enhanced spectroscopy (CES) was utilized, with an effective path length of 670 m. Both sensors enabled simultaneous analysis of NO and CO2 concentrations in exhaled air. The minimum detectable NO concentration was found to be 3 ppb with a multi-pass cell and 16 ppb when using CES. The two techniques are compared, and potential future developments are discussed.

Breath Tests↗
PubMed2001

Clavaspirin, an antibacterial and haemolytic peptide from Styela clava.

We cloned the precursor of a novel peptide from a cDNA library prepared from pharyngeal tissues of the tunicate, Styela clava. Its sequence predicted a histidine-rich, amidated 23-residue peptide (FLRF(IG)SVIHGIGHLVHHIGVAL-NH2) that we named clavaspirin. A synthetic clavaspirin was prepared and it was found that it killed Gram-positive and Gram-negative bacteria, permeabilized the outer and inner membranes of Escherichia coli, lysed phosphatidylglycerol (POPG) liposomes, and was potently haemolytic towards human and bovine erythrocytes. Each of these activities was performed more effectively at an acidic pH. Circular dichroism measurements of synthetic clavaspirin revealed a largely alpha-helical structure and polarized and residue-specific FTIR spectrometry showed that its association with phospholipid membranes was influenced by pH. Peptides such as clavaspirin may equip tunicate haemocytes to mediate cytotoxicity and participate in antimicrobial defence.

Amino Acid Sequence↗
PubMed1999

LMR spectroscopy: a new sensitive method for on-line recording of nitric oxide in breath.

Laser magnetic resonance spectroscopy (LMRS) is a sensitive and isotope-selective technique for determining low concentrations of gaseous free radicals with high time resolution. We used this technique to analyze the nitric oxide (NO) concentration profile while simultaneously measuring the flow and expired volume during several single breathing cycles. Eight healthy, nonallergic volunteers were investigated. An initial NO peak was found in all breathing cycles before the NO concentration dropped to a relatively stable plateau in the late phase of expiration. The nasal NO peak was significantly higher than the oral NO peak. The nasal NO plateau was always higher than the oral NO plateau. The height of the initial nasal and oral NO peak rose with increasing duration of breath hold, whereas the late expiratory NO plateau changed only little for either the nasal or the oral breathing cycles. Our findings demonstrate, in line with other reports using other techniques, that the nose is the primary source for NO within the airways.

Adult↗
PubMedDate not supplied

Survival experience of chronically critically ill patients.

Intensive care unit (ICU) patients were randomly assigned to either a traditional ICU or a special care unit (SCU) for chronically critically ill patients. The SCU used a low-technology, family-oriented environment, nursing case management, no physician house staff, and a shared governance model. In comparison, the ICU used high technology, limited family visiting, primary care nursing, and a bureaucratic management model. The survival experience of chronically critically ill patients in the two environments during hospitalization, as well as after hospital discharge, was examined. Using survival analytic techniques, the 1-year cumulative mortality for all patients in the study was found to be 59.9%. Risk of death was significantly lower after discharge than during hospitalization. Similar mortality experiences were found for SCU and ICU patients. Thus, the high-technology ICU environment did not produce better outcomes than the SCU environment.

Aged↗
PubMedDate not supplied

Menstrual response to running: nursing implications.

Overt (length of menstrual cycle, duration of menses, and amount of menses) and covert (luteal surge indicative of ovulation and length of luteal phase) menstrual cycle characteristics were studied in a sample of 146 women who participated in four levels of running intensity. Menstrual and running data were collected for 4 months or 3 cycles. There was a significant difference among the four groups in duration of menses and in the amount of menses, with nonrunners having significantly more days of menses and larger amounts of menses than the two highest intensity running groups. However, when a history of skipping menstrual periods between menarche and age 18 was controlled, the differences between the groups were not significant. There were no significant differences among the four groups in incidence of luteal surge or length of luteal phase. When runners were compared to nonrunners, runners reported, on average, a shorter luteal phase than nonrunners. This difference remained when controlling for age and history of skipping menstrual periods. There was no significant difference between the four groups on incidence of ovulatory disturbances (anovulation or more than one cycle with a shortened luteal phase). But, when compared to nonrunners, runners were found to have significantly more ovulatory disturbances. The best predictors of the variance in menstrual cycle characteristics were history of skipping periods between menarche and age 18, and running versus nonrunning.

Adipose Tissue↗