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Biomedical subjects

M Halpern

Publications and source records attributed to M Halpern.

At least 109 records · Page 6Linked to original sources
PubMed1989

Chemical access to the vomeronasal organs of the lizard Chalcides ocellatus.

A functional association between tongue flicking and vomeronasal organ chemoreception in lizards has been assumed frequently, but never tested. To test this hypothesis, a cotton swab soaked in prey extract mixed with [3H]proline was touched ten times to the snouts of normal and tongueless lizards (Chalcides ocellatus), as well as normal lizards whose vomeronasal organ (VNO) ducts had been sealed with a tissue adhesive. Additionally, such a swab was held approximately 0.5 cm in front of the snout of normal and tongueless lizards for 1 min, which allowed no contact by tongueless animals and tongue contact only by normal lizards. Using autoradiography, substantial and comparable concentrations of labeled molecules were detected in the mouths, VNO ducts, and VNOs of normal subjects in both conditions, as well as tongueless lizards whose snouts made physical contact with swabs. No label was evident in VNOs of tongueless animals that did not contact swabs or normal animals with sealed VN ducts. Labeling was not apparent generally in the olfactory epithelium. These results suggest that: 1) the tongue is not required for, nor does it increase, chemical delivery to VNOs when snout contact occurs; 2) the tongue transfers molecules from the external environment to the oral region; 3) it is unlikely that nonvolatile chemicals reach the olfactory epithelium via an oral route; and 4) tissue adhesive is an effective means of preventing chemical access to the VN organs.

Animals↗
PubMed1989

In vitro technique for studying garter snake (Thamnophis sp.) development.

Garter snake (Thamnophis sp.) embryos of different embryonic ages were explanted from pregnant females and grown in vitro for up to 35 days. The culture medium consisted of Eagle's Minimum Essential Medium with various organic and inorganic supplements and antibiotics. Cultured embryos were injected with tritiated thymidine, sacrificed, and processed for autoradiographic examination. The in vitro technique allowed direct visualization of external morphologic changes over time, which followed a timetable similar to that of embryos growing in vivo. This technique also allowed easier manipulation of embryos for determination of embryonic stage and for injection of tritiated thymidine. This is the first report of long-term culture of snake embryos which adds to the limited number of reptilian embryos that have been studied in vitro.

Animals↗
PubMed1989

Isolation and characterization of alarm pheromone from electric shock-induced earthworm secretion.

Electric stimulation of earthworms, Lumbricus terrestris, causes secretion of a yellow mucus which has alarm properties for conspecifics and chemoattractive properties for garter snakes. An alarm pheromone was isolated and purified to homogeneity from the mucus by means of permeation, thin-layer and high performance liquid chromatographies. The purified substance was highly active as an alarm chemosignal to earthworms (L. terrestris), but it did not elicit alarm responses from either sandworms (Nereis virens) or bloodworms (Glycera debranciata). It was not a snake chemoattractant. The alarm pheromone could not be retained with 1 kDa cut-off dialysis tubing, and it was eluted from a Bio-gel P2 column ahead of p-nitrophenol. These data suggest an apparent mass greater than 139 Da but less than 1 kDa. The order of solubility of this alarm pheromone is H2O greater than DMSO greater than MeOH greater than 2-propanol greater than acetone. It was thermostable, and it fully retained activity after heating at 100 degrees C for 1 hour. This alarm pheromone fluoresced under u.v. light, and it showed an optimal excitation wavelength of 420 nm and emission wavelength of 465 nm.

Animals↗
PubMed1989

Amyloid goiter.

A case of a 50-year-old patient suffering from secondary amyloidosis presenting with amyloid goiter is described. The diagnostic and therapeutic implications are reviewed.

Amyloidosis↗
PubMed1988

Neurogenesis in the vomeronasal epithelium of adult garter snakes: 3. Use of H3-thymidine autoradiography to trace the genesis and migration of bipolar neurons.

Use of H3-thymidine autoradiography and unilateral vomeronasal (VN) axotomy has permitted us to demonstrate directly the existence of VN stem cells in the adult garter snake and to trace continuous bipolar neuron development and migration in the normal VN and deafferentated VN epithelium in the same animal. The vomeronasal epithelium and olfactory epithelium of adult garter snakes are both capable of incorporating H3-thymidine. In the sensory epithelium of the vomeronasal organ, H3-thymidine-labeled cells were initially restricted to the base of the undifferentiated cell layer in animals surviving 1 day following H3-thymidine injection. With increasing survival time, labeled cells progressively migrated vertically within the receptor cell column toward the apex of the bipolar neuron layer. In both the normal and denervated VN epithelium, labeled cells were observed through the 56 days of postoperative survival. In the normal epithelium, labeled cells were always located within the matrix of the intact receptor cell columns. However, labeled cells of the denervated epithelium were always located at the apical front of the newly formed cell mass following depletion of the original neuronal cell population. In addition, at postoperative days 28 and 56, labeled cells of the denervated VN epithelium achieved neuronal differentiation and maturation by migrating much farther away from the base of the receptor cell column than the labeled cells on the normal, unoperated contralateral side. This study directly demonstrates that basal cells initially incorporating H3-thymidine are indeed stem cells of the VN epithelium in adult garter snakes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Isolation from earthworms of a proteinaceous chemoattractant to garter snakes.

We have isolated a potent proteinaceous chemoattractant from aqueous washes of earthworm (Lumbricus terrestris) for garter snakes (Thamnophis sirtalis) by means of a covalent chromatography. It contained free sulfhydryl groups and showed an apparent mass of 20 kDa. The chemoattractive activity of this protein could be destroyed by heating as well as by proteolysis. Its activity could also be reversibly blocked by mixed disulfide formation with dithiodipyridine, suggesting that the free sulfhydryl(s) was essential for its function as a chemoattractant. This bioactive material had a tendency to form intermolecular crosslinked aggregates during isolation, if reducing agents were not included. Some of the high-molecular-weight aggregates cochromatographed with earthworm cuticle collagen on Ultragel AcA 34 or 44 columns. In contrast to an earlier report by D. M. Kirschenbaum, N. Schulman, and M. Halpern [1986) Proc. Natl. Acad. Sci. USA 83, 1213-1216) the purified earthworm collagen showed no chemoattractive activity to garter snakes.

Animals↗
PubMed1988

Neonate plains garter snakes (Thamnophis radix) are attracted to conspecific skin extracts.

Several species of snakes aggregate in areas previously marked by conspecifics. However, species differences and sources of such chemical signals have received little attention. Methylene chloride-soluble substances from shed epidermis of adult plains garter snakes attracted neonate conspecifics, whereas similar extracts from a congener and a viperid did not. The functional significance of such conspecific aggregation may relate to location of hibernacula, foraging areas, osmoregulation, or predation avoidance.

Animals↗
PubMed1987

Evaluation of a minimal-therapist-contact thermal biofeedback treatment program for essential hypertension.

We compared a clinic-based regimen of 16 individual sessions (2 per week) of thermal biofeedback with a largely home-based regimen of 5 sessions (spread over 8 weeks) for the treatment of essential hypertension in patients who required at least two drugs to maintain control of blood pressure (BP). On the basis of the clinical end point of being successfully withdrawn from the second stage medication while BP remained under control, the clinic-based regimen (5 of 9) was superior (chi less than (1) = 4.0, p less than .05) to the home-based regimen (1 of 9). Internal analyses point to more frequently obtaining a hand temperature of at least 95 degrees F by the office-based patients as possibly the reason for the difference.

Adult↗
PubMed1986

Earthworms produce a collagen-like substance detected by the garter snake vomeronasal system.

Earthworms (Lumbricus terrestris) produce a chemical substance that is readily detected by and serves as an attractant for garter snakes (Thamnophis sirtalis). This chemoattractant is sensed by the vomeronasal system of snakes. Amino acid analysis of the chemoattractant revealed a high hydroxyproline/proline ratio and large amounts of serine and threonine. More than one-third of the residues were glycine. No hydroxylysine and no cysteine were present. Carbohydrate analyses revealed a high content of galactose (11% by weight) and smaller amounts of fucose, mannose, glucose, N-acetylglucosamine, and N-acetylgalactosamine. These results were very similar to results reported for the amino acid composition and carbohydrate content of earthworm cuticle collagen and gelatin. A preparation of purified earthworm cuticle collagen proved to be a potent source of chemoattractant for garter snakes. Further, it was not possible to prepare chemoattractant from decuticlized earthworms. These results strongly suggest that a component of the earthworm chemoattractant for snakes is structurally related to earthworm cuticle collagen.

Animals↗
PubMed1986

Genetic toxicology of flavonoids: the role of metabolic conditions in the induction of reverse mutation, SOS functions and sister-chromatid exchanges.

Glycosides of flavonols such as quercetin, are found in the edible portions of most food vegetables. Flavonols present in plants as glycosides can be freed during fermentation. We have compared the DNA-damaging activity of quercetin, rutin (3-o-rutinoside of quercetin) and a fermented flavonoid-containing beverage, red wine, for different genetic end-points under different metabolic conditions. The genotoxicity of quercetin, rutin and commercial red wine has been studied for the induction of: (i) reverse mutation in the Ames assay; (ii) SOS functions in the SOS Chromotest; (iii) sister-chromatid exchanges (SCEs) in human lymphocytes. While in the Ames assay the mutagenicity of quercetin is enhanced by the presence of rat liver microsomal enzymes (S9) or the respective cytosolic fraction (S100), genotoxicity is reduced when the induction of SOS responses is assessed using the SOS Chromotest. Similarly, the induction of SCEs is lowered when testing in the presence of liver enzymes. Rutin has no activity whatsoever. Detection of activity of red wine in the three assays is not dependent upon hydrolysis by glycosidases and its content of quercetin accounts almost entirely for the levels of genotoxicity detected. The results suggest that the putative genotoxic metabolites of quercetin vary for different genetic end-points considered and that the metabolic fate of flavonoids might partly account for the conflicting data about their genotoxicity in vivo and carcinogenic activity.

Animals↗
PubMed1985

Chemo-attractant for the garter snake: characterization of vomeronasally-mediated response-eliciting components of earthworm wash--III.

Heating a 0.1 N HCl solution of lyophilized garter snake, Thamnophis sirtalis, chemoattractant obtained from earthworm, Lumbricus terrestris, surface washings, in a boiling water bath, and separation by gel chromatography, gave two fractions, F2, of high molecular weight and containing all the chemoattractant activity, and F4, of low molecular weight. The activity is lost between 15 and 30 min of heating. A similarly treated 0.1 N NaOH solution of lyophilized washings gave no F2 fraction and an F4 fraction in increasing amount. All the chemoattractant activity is lost between 0 and 15 min. Separations were monitored by assays for protein and carbohydrate.

Animals↗
PubMed1985

Tubular duplication of the jejunum and ileum lined entirely by gastric mucosa.

A 3-year-old boy who suffered from severe colicky abdominal pain is presented. Laboratory studies, including ultrasound, upper gastrointestinal films, and 99mTc-scan, were interpreted as normal. On exploration of the abdomen a tubular duplication of the small bowel was found. The duplication had a common mesentery with the normal bowel. By meticulous dissection the duplication was resected without interfering with the blood supply of the normal bowel. The entire duplication was found to be covered by gastric mucosa.

Abdomen↗
PubMed1984

Segmental organization of rat lateral longissimus, a muscle involved in lordosis behavior: EMG and muscle nerve recordings.

Following stimulation of lumbar cutaneous and high threshold muscle afferents in urethane-anesthetized ovariectomized rats, polysynaptic multi-unit responses were recorded from muscle nerves to lateral longissimus (LL) at a mean latency of 9.5 ms. These responses could be reciprocally evoked between segments with no apparent rostro-caudal asymmetry. Polysynaptic responses habituated to repeated stimulation within 0.5-1.5 min but could be evoked again after several minutes rest. In estradiol-treated rats, 60% of the 9.5 ms responses were followed by late discharges (greater than 40 ms) as compared to 24% in untreated control animals (P = 0.05). Following stimulation to the L3 and L4 motor nerves to lateral longissimus, EMG responses were recorded from overlapping fields of innervation. The conduction velocity of the fast muscle fibers was determined to be 7 m/s. The short length of most of the LL muscle fibers and the intersegmental recruitment of LL motoneurons by cutaneous afferents is compatible with the integrated action of axial muscles in the performance of lordosis behavior.

Animals↗