Ernst Friedrich Gurlt (1794-1882)

Ernst Friedrich Gurlt (1794-1882) is the founder of the comparative veterinary anatomy on a solid scientific basis. The integration of the human being into the comparative study and the continuous linkage between human anatomy and veterinary anatomy feature him in the same time as a distinguished pioneer of the comparative anatomy. Beside this, Gurlt has merits in physiology and post mortem anatomy. This publication contains a short life story and a laudation of the work of Ernst Friedrich Gurlt, which was active at the Veterinary School at Berlin more than a half century, from 1819 to 1870.     

Stress-induced hypokinesia is facilitated by ACTH-(7-10)

Subcutaneous treatment with the neuropeptide ACTH-(4-10) induced hypokinesia in rats subjected to a mild stress induced by placing the animals on a non-functional "hot" plate (21 degrees C) for 30 sec, but not in control animals not exposed to this stress-inducing environment. The lowest effective dose of ACTH-(4-10) was 5 micrograms/kg, administered 50 min before testing. The combination of peptide treatment and the mild stress-inducing procedure mimicked the effect of a short intense stress induced by placing the rats on a hot plate (57 degrees C) for 30 sec, suggesting that this stress-induced hypokinesia is mediated by ACTH neuropeptides. Structure-activity relationship studies revealed that the active core for the ACTH-(4-10)-induced hypokinesia is located in the C-terminal tetrapeptide Phe-Arg-Try-Gly (ACTH-(7-10)). Pretreatment with the opioid antagonist naltrexone did not influence the effect of ACTH-(4-10) indicating that activation of opioid systems is not implicated in this behavioral effect of the peptide.     

Measurement of 10(-7) to 10(-12) mol of potassium by stimulation of pyruvate kinase.

A method for measuring potassium is described which is based on the requirement of pyruvate kinase for this cation. Activity of this enzyme is linear with respect to potassium concentration between 10 and 100 μm. The rate of pyruvate formation is measured with lactic dehydrogenase and NADH in a coupled assay. Other common cations do not interfere at concentrations likely to be present. With a variety of plant extracts, potassium concentrations obtained with the assay were in agreement with those obtained using a flame photometer. For measuring smaller amounts of potassium the reaction is carried out in a small volume and the NAD⁺ produced is converted to a highly fluorescent product or is amplified by enzymatic cycling. These procedures have been tested extensively only on plant material, but the assay should be generally applicable.     

7-(4-Alkylidenylpiperidinyl)-quinolone bacterial topoisomerase inhibitors

Novel antibacterial fluoroquinolone agents bearing a 4-alkylidenylpiperidine 7-position substituent are active against quinolone-susceptible and quinolone-resistant gram-positive bacteria, including Streptococcus pneumoniae and MRSA. Analogs 22b, 23c, and 24 demonstrated superior in vitro and in vivo efficacy to ciprofloxacin against these cocci.     

Dynorphin(1-10)amide: a potent and selective analog of dynorphin(1-13)

Dynorphin(1-10)amide was more potent than Dynorphin(1-13) in inhibiting the twitch of the mouse vas deferens (IC50 of Dynorphin(1-10)amide = 0.3 nM and IC50 of Dynorphin (1-13) = 4.0 nM). Binding assays indicated that two opioid peptides had similar profiles in that they enhanced dihydromorphine (DHM) binding in picomolar concentrations but displaced DHM binding in nanomolar concentrations (IC50 for Dynorphin(1-10)amide = 5 nM). In the mouse tail-flick assay, however, Dynorphin(1-10)amide showed a more selective action on morphine-induced analgesia. Although Dynorphin(1-10)amide had no significant analgesic activity by itself, it differed from the (1-13) analog by neither potentiating nor antagonizing morphine in naive animals. In tolerant animals, on the other hand, 50 microgram of this analog administered icv shifted the ED50 of morphine from 43.0(33.0-55.9) to 17.0 (12.4-23.3). Thus, Dynorphin(1-10)amide appears to be a more potent and selective analog of Dynorphin(1-13).     

Precursor forms of neurotensin (NT) in cat: processing with pepsin yields NT-(3-13) and NT-(4-13)

Basic proteins present in 0.1 N HCl extracts of feline CNS and intestine were found to liberate immunoreactive neurotensin (iNT) when treated with hog pepsin. These protein substrates were separated using Sephadex G-25, Sephadex G-75 and reverse-phase HPLC. In a calibrated SDS-polyacrylamide gel electrophoresis system, the major substrate from cat ileum exhibited a molecular weight of ca 16 kDa and minor substrates were observed at 30, 40 and 65 kDa. As shown previously for synthetic NT, pepsin-treatment of feline ileal NT converted it into the fully immunoreactive NT-(4-13) fragment (yield, 95%). When treated with pepsin, the partially purified ileal substrates gave rise to 4 immunoreactive peptides, one of which (ca 15% of total) eluted with the same retention time as NT-(4-13) while the major peptide formed (ca 40% of total) eluted near to the position of NT-(3-13). Both these products reacted equally well with two different antisera towards the C-terminal 5- and 8-residues of NT and were not recognized by an N-terminal antiserum. Experiments using various proteases demonstrated that the NT-related sequence(s) were located internally in each substrate and suggested that they were bounded by double basic residues. Substrate activity in isotonic homogenates of feline spinal cord, brain, adrenal and ileum cosedimented with iNT during equilibrium centrifugation, apparently in association with vesicle and/or synaptosomal particles. These findings indicate that basic proteins, colocalized with NT in vesicle-like particles of CNS, adrenals and ileum, could serve as precursors to this peptide, being liberated by pepsin-related enzyme(s).     

Potential antitumour and pro-oxidative effects of (E)-methyl 2-(7-chloroquinolin-4-ylthio)-3-(4-hydroxyphenyl) acrylate (QNACR)

Context: Characterization of the pro-oxidant activity of QNACR.

Objectives: Reactive oxygen species (ROS) induce cellular damage and represent unique opportunities to kill malignant cells. In this study, we synthesized and evaluated the new compound, (E)-methyl 2-(7-chloroquinolin-4-ylthio)-3-(4-hydroxyphenyl) acrylate (QNACR) as potential pro-oxidative agent against breast cancer.

Methods: Oxidative stress biomarkers such as ROS, thiobarbuturic acid reactive species (TBARs) and different antioxidant enzyme activities were determined in cell lysates.

Results: QNACR showed cytotoxic and more selective effects to tumour MCF7 cells (IC₅₀ < 25 µM) compared to antitumour controls, inducing ROS and TBARs parallel to inhibitions of catalase (CAT), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH). Longer exposures to QNACR triggered adaptive effects increasing the overall activities of CAT, glutathione reductase, G6PDH and 6PGDH, but eventually the adaptation changes faded and cells died.

Conclusion: QNACR led to remarkable modifications in the oxidative status of tumour cells, proposing this compound as potential alternative for antitumour therapy.     

Cetacean strandings in Costa Rica (1966-1999)

Cetacean strandings in Costa Rica are reported for a period of 33 years, with a total of 35 strandings, 13 species and 247 individuals involved. The vast majority of documented strandings occurred on the Pacific coast and correspond to single individuals (32 and 28 strandings respectively). The highest stranding number was in the period from 1990 to 1999 (n = 24). Physeter catodon (cachalot or sperm whale) is the species with the highest frequency of strandings (n = 8) and the family Delphinidae has the majority of species (n = 8) and strandings (n = 22). No other general tendencies were determined with the existing data.