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Biomedical subjects

M Eisner

Publications and source records attributed to M Eisner.

At least 37 records · Page 2Linked to original sources
PubMed1996

Chemical basis of courtship in a beetle (Neopyrochroa flabellata): Cantharidin as "nuptial gift".

The amount of cantharidin (Spanish fly) that the Neopyrochroa flabellata male presents to the female as a glandular offering during courtship represents only a small fraction of the total cantharidin the male accumulates systemically following ingestion of the compound. A major fraction of the acquired cantharidin is stored by the male in the large accessory glands of the reproductive system. At mating, the male transfers this supply, presumably as part of the sperm package, to the spermatheca of the female. The female in turn allocates the gift to the eggs. Eggs endowed with cantharidin proved relatively invulnerable to attack by a predaceous beetle larva (Coleomegilla maculata).

Animals↗
PubMed1996

Chemical egg defense in a green lacewing (Ceraeochrysa smithi)

The green lacewing Ceraeochrysa smithi (Neuroptera, Chrysopidae), like other members of its family, lays its eggs on stalks, but it is unusual in that it coats these stalks with droplets of an oily fluid. The liquid consists of a mixture of fatty acids, an ester, and a series of straight-chain aldehydes. Relative to the eggs of a congeneric chrysopid that lacks stalk fluid, the eggs of C. smithi proved well protected against ants. Components of the fluid, in an assay with a cockroach, proved potently irritant. Following emergence from the egg, C. smithi larvae imbibe the stalk fluid, thereby possibly deriving nutritive benefit, defensive advantage, or both.

Aldehydes↗
PubMed1994

Defensive use of an acquired substance (carminic acid) by predaceous insect larvae.

Larvae of two insects, a coccinellid beetle (Hyperaspis trifurcata) and a chamaemyiid fly (Leucopis sp.), feed on cochineal insects and appropriate their prey's defensive chemical, carminic acid, for protective purposes of their own. H. trifurcata discharges the chemical with droplets of blood (hemolymph) that it emits when disturbed; Leucopis sp. ejects the compound with rectal fluid. Ants are thwarted by these defenses, which are compared with the previously-described defense of a pyralid caterpillar (Laetilia coccidivora) that disgorges carminic acid-laden crop fluid. The defensive fluid of all three larvae contains carminic acid at concentrations spanning a range (0.2-6.2%) proven deterrent to ants. Many insects are known to appropriate defensive substances from plants. Insects that acquire defensive chemicals from animal sources may be relatively rare.

Animals↗
PubMed1994

The fundamental unit of synthetic melanin: a verification by tunneling microscopy of X-ray scattering results.

A characteristic dimension of a melanin protomolecule synthesized from tyrosine has been investigated by scanning tunneling microscopy (STM). Identification of a melanin protomolecule of approximately approximately 20 A lateral extent and approximately 10 A height has been established. This size is in good agreement with models constructed to fit wide angle X-ray diffraction experiments on melanin. These protomolecules are believed to consist of Van der Waals interacting stacks of a basic random polymer of 5.6 indolequinone units. There is extensive pi-delocalization within the individual polymeric sheets. Structure minimization and molecular orbital techniques were employed to verify the X-ray and STM results.

Melanins↗
PubMed1994

X-ray characterization of melanins--I.

The intrinsic local structure characterization of natural sepia melanin and L-dopa and tyrosine synthetic melanin powder has been carried out by X-ray diffraction using synchrotron radiation. The derived structure factor, S(q), shows six significant diffuse peaks within the q-range from 0.3 A-1 to 16 A-1 in the reciprocal space (q = (4 pi sin theta)/lambda, 2 theta is the scattering angle). The Fourier transform of S(q), which yields the radial distribution function (RDF), gives us information in real space of a 1.42 A distance averaged over the C-C, C-O and C-N bond lengths as well as peaks at 2.40-2.41 A, 3.67-3.71 A and 4.67-4.70 A discrete neighbor distances. There is a great similarity in the scattering intensity profiles of the natural and synthetic melanins indicating that the synthetically prepared material may be essentially similar to "real" melanin in its local atomic arrangements. An evidence of a prepeak at q congruent to 0.45 A-1 has been confirmed which indicates a preferred length scale of approximately 13-20 A that corresponds to the initial particle size in colloidal melanin solutions.

Animals↗
PubMed1994

X-ray characterization of melanins--II.

Structural modeling of amorphous eumelanin has been carried out by comparing calculated data, S(q) and RDF(r), in reciprocal and real space, respectively, for limited random network models with the experimental X-ray scattering data of tyrosine melanin (Cheng et al., 1994). A basic picture of the atomic arrangements in amorphous eumelanin, which accounts for the short and intermediate range order, has been formulated. This reveals domains of a fundamental "particle" dimension of R approximately 15 A, consisting of a paracrystalline array of disordered planar networks polymerized by 4-8 DHI monomers with a graphite-like stacking spacing of approximately 3.45 A, 4-5 layers thick.

Chemical Phenomena↗
PubMed1991

Chemical attraction of kleptoparasitic flies to heteropteran insects caught by orb-weaving spiders.

Insects of the heteropteran families Pentatomidae (stink bugs) and Coreidae (squash bugs), when being eaten by the orb-weaving spider Nephila clavipes, attract flies of the family Milichiidae. The flies aggregate on the bugs and, as kleptoparasites, share in the spider's meal. Stink bugs and squash bugs typically eject defensive sprays when attacked; they do so when caught by Nephila, but the spray only minimally affects the spider. Evidence is presented indicating that it is the spray of the bugs that attracts milichiids to the spider's catch.

Aldehydes↗
PubMed1990

Endoscopic lithotripsy of biliary stones.

Historically, gallstone therapy has been surgery. Gastrointestinal endoscopists and radiologists are now becoming increasingly active in the definitive management of both cholelithiasis and choledocholithiasis. Today, for uncomplicated cholelithiasis and for many cases of choledocholithiasis in patients without increased surgical risk, biliary surgery remains the recommended treatment by internists and surgeons alike. However, with an increased battery of available therapeutic modalities, management decisions and strategies are becoming more complex and the treatment of biliary stone disease in the future will be different than it was in the past.

Cholelithiasis↗
PubMed1987

Presenting characteristics of patients with duodenal ulcer and outcome of medical treatment in controlled clinical trials using cimetidine and diethylamine persilate to treat ulcer attack and diethylamine persilate and placebo to prevent relapses.

A double-blind controlled clinical trial on the medical treatment of the acute episode of duodenal ulcer and the prevention of symptomatic relapses was performed. A total of 164 patients with active duodenal ulcer were either treated with cimetidine 1 g/day (70 patients), diethylaminepersilate (DAP) 1.5 g/day (64 patients) or DAP 2.5 g/day (30 patients). DAP is an allegedly protective agent stimulating mucosal prostaglandin synthesis. Cumulative healing rates after 4 weeks in the 3 groups were 66, 28 and 28% and after 8 weeks 94, 70 and 63%, respectively. One hundred and five patients with healed duodenal ulcer received, in a second double-blind study, either DAP 0.5 g/day or placebo. Thus, ulcer healing was more rapid with cimetidine than with DAP. DAP did not prevent relapses. No presenting characteristic was associated with slow healing. Three presenting characteristics--smoking, teetotalling and bleeding episode in the past--were associated with early symptomatic relapse. The present study was compared with a previous study performed by the same group of investigators using a similar study protocol. In both trials, an early relapse was associated with smoking. No other presenting characteristic was identified which in both trials was associated with slow healing or early symptomatic relapse. Thus, smoking appears to be the only one of the commonly available presenting characteristics which allows a prediction of the course of duodenal ulcer disease.

Adult↗
PubMed1985

[Misoprostol and cimetidine in the treatment of duodenal ulcer. A multicenter Swiss double-blind study].

The efficacy and tolerance of misoprostol a synthetic prostaglandin E1 analogue-and of cimetidine were evaluated in the treatment of duodenal ulcer following a double blind multicenter design. A group of Swiss gastroenterologists recruited 119 patients with endoscopically proven acute duodenal ulcer. They were enrolled and treated according to a uniform protocol either with misoprostol 4 X 50 micrograms daily, with misoprostol 4 X 200 micrograms daily or with cimetidine 4 X 300 mg daily. Patients who were healed after 4 or 8 weeks were followed during 6 months. Cumulative healing rates at 4 weeks in groups receiving misoprostol 200 micrograms, misoprostol 800 micrograms or cimetidine 1200 mg daily were 42%, 58% and 71% respectively. Patients treated with cimetidine showed a more rapid improvement of symptoms than patients treated with misoprostol. Symptomatic recurrences after ulcer healing occurred in almost 40% of the patients within 6 months, irrespective of the type of acute ulcer treatment. Risk factors for slowed healing and increased rate of recurrence were evaluated in the present study, and the results were compared with the results of two previous trials performed according to a similar protocol. Smoking appeared to slow healing and to favor relapses. Moderate consumption of alcohol appeared to decrease the relapse rate. In the present trial, ulcer size was associated with ulcer pain but not with ulcer healing.

Adult↗
PubMed1984

[Midazolam as a premedication for gastroscopy].

Midazolam (Ro 21-3981; Dormicum ) is a new water-soluble benzodiazepine. Compared with diazepam and flunitrazepam, it has the advantage of a short half-life and good tolerability after intravenous administration. It induces light sleep 1/2 to 2 min after injection, and anterograde amnesia. It has minimal hemodynamic and respiratory effects. We administered midazolam by intravenous injection in a dose of 3-7 mg to 100 patients about to undergo esophago-, gastro-, or duodenoscopy. The patient became quiet and relaxed, falling into a light sleep but remaining capable of following simple instructions. After completion of the endoscopy, the patients were half awake, and listened attentively to the report. They subsequently usually slept for 1-2 h, afterwards remembering nothing of the procedure. Two (at most, 3) hours after injection, the patients were again completely awake and able to go home or back to work. In some cases, concentration was slightly impaired for the rest of the day. Compared with other premedications , midazolam is better suited for use in endoscopy, owing to its rapid onset and short duration of action.

Adult↗
PubMed1983

Intrauterine exposure to halothane increases murine postnatal autotolerance to halothane and reduces brain weight.

The effect of halothane on prenatal development was assessed using the appearance of postnatal tolerance to the anesthetic and its effect on brain weight. Eighteen 3-month-old mice were repeatedly tested in a rotating cage for loss of righting reflex during exposure to increasing concentrations of halothane on 15 occasions to determine whether or not tolerance to halothane developed. Of these, nine mice were born to dams exposed for 30 min to 2% halothane on days 14 and 17 of gestation. The other nine mice (controls) were born to dams exposed to 100% oxygen for 30 min at the same stage of pregnancy. There was no significant difference in tolerance to halothane between the groups during the first nine days of repeated exposure to halothane. By the 13th and 15th days, however, mice exposed to halothane in utero became more tolerant to 1% halothane than did controls (P less than 0.025). In addition, the mean total brain weight of six 7-week-old mice exposed to 2% halothane in utero for 30 min on days 14 and 17 of gestation was found to be significantly less than the mean total brain weight of six control mice not exposed to halothane in utero (20.83 +/- 0.27 g and 23.07 +/- 0.51 g, respectively, P less than 0.0025). This difference occurred mainly in the brain stem rather than in the forebrain and cerebellum.

Animals↗
PubMed1982

Meperidine-promethazine combination and learning function of mice and of their progeny.

Twenty mice aged three to four months and trained to find food in a six compartment maze after a 24 hour fast, were divided into two equal groups. For just over one month the group which had received intraperitoneal meperidine 3 microgram.g-1 and promethazine 1.66 microgram.g-1 performed significantly slower than the group which had received intraperitoneal physiological saline. Because of this marked effect, it was decided to investigate the action of the drug combination on brain development and to assess whether it produced permanent retardation in learning function. The dams of a second group of 12 mice were, therefore, given either the same dose of drug combination or saline. At the age of seven weeks, the six pups born to dams which had received intramuscular saline and the six born to dams which were given intramuscular promethazine with meperidine performed equally well in a series of tests conducted in a T maze and in the six compartment maze after a 24 hour fast. In the T maze they had to distinguish between the presence of food provided in diminishing amounts or no food. In the six compartment maze they were tested with multiple maze pattern sequences. Meperidine and promethazine given during early labor does not permanently affect the learning function of the progeny of mice.

Aging↗
PubMed1981

Exposure to halothane and enflurane affects learning function of murine progeny.

This study was conducted to assess the learning function of murine progeny born of mothers that had received either 1% or 2% halothane or 2% or 4% enflurane, on days 6 and 10 or days 14 and 17 or gestation. Their timed performance at the age of 6 to 7 weeks was compared in a maze with that of control mice of similar ages that had not been exposed to anesthetics prenatally. All mice exposed to halothane in utero performed poorly at first, especially the group with mothers exposed to 2% halothane on days 14 and 17 of pregnancy. By the 10th training period, the performance of all mice improved but remained significantly slower than control mice. The offsprings of mice exposed to enflurane also performed poorly on the first training period, but between the fifth and seventh training periods, made statistically significant progress. However, they too remained slower in maze performance than control mice. Although blood pressure and arterial blood gas studies were only performed on two pregnant mice, data obtained suggest that the anesthetics did not have sufficient effect on respiration to affect our results. Second generation offspring, born to dams exposed to 2% halothane in utero late in pregnancy and sired by normal unexposed males, were also consistently slower than control mice, indicating a possible genetic effect induced by the anesthetic.

Animals↗