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Biomedical subjects

M Halpern

Publications and source records attributed to M Halpern.

At least 127 records · Page 7Linked to original sources
PubMed1984

Preliminary results from a controlled evaluation of thermal biofeedback as a treatment for essential hypertension.

In a controlled trial, thermal biofeedback (n = 20) and abbreviated progressive relaxation (n = 22) were compared in the treatment of mild to moderate hypertensive patients whose blood pressures (BP) were initially controlled on two medications. For the clinical end point of maintaining control of BP on a single drug after treatment, biofeedback was superior to relaxation training (at 3 months, 47% success for biofeedback versus 23% for relaxation). This same result tended to be true for patient-measured home BPs. BPs from laboratory psychophysiological testing showed no consistent advantage for one treatment over the other.

Adult↗
PubMed1984

Characterization of vomeronasally-mediated response-eliciting components of earthworm wash-II.

Garter snakes reliably spend more time and tongue flick more frequently at a dish containing surface washings of earthworm (EW) than at a control dish containing water or sodium chloride. In a series of experiments EW was examined to further characterize and purify the snake-attracting component(s). Earthworm wash boiled for up to two hours did not lose its snake-attracting activity, but EW boiled for four hours was not discriminated from a control substance. The active components of EW were completely precipitated by 90 and 100% saturated ammonium sulfate solutions. The molecular weight of the active components, as determined by dialysis, is larger than 67,000 daltons. Earthworm wash was separated into two peaks on either G-75 or AcA 44. The larger peak (F2) contains snake-attracting material of molecular weight greater than 67K. The smaller peak material (F4) is inactive as a snake-attractant and contains material of approximate molecular weight of 3K. Biological activity of EW covaried with Lowry (protein) assay and Dubois (carbohydrate) assay values and 280 nm absorbance. The response eliciting components of EW are not extractable from earthworms at temperatures below 60 degrees C, but can be extracted at 60 degrees C (for one minute) from the worms or the soil that forms the bedding for the earthworms.

Ammonium Sulfate↗
PubMed1984

Periarticular calcifications in association with intra-articular corticosteroid injections.

The authors report on three patients who received intra-articular corticosteroid injections (IACI) in the small joints of their hands for the symptomatic relief of local inflammation. In these cases radiographs showed that among the complications of IACI are periarticular soft-tissue calcifications. Evidence suggests that these calcifications are composed of hydroxyapatite crystals, which may themselves produce inflammatory arthritis.

Adult↗
PubMed1983

Preliminary characterization of response-eliciting components of earthworm extract.

Fifteen garter snakes (Thamnophis sirtalis) reliably spent more time and tongue flicked more frequently at a dish containing earthworm extract than a dish containing distilled water when these were presented simultaneously for two minute intervals. The discriminability of the earthworm extract was directly related to its concentration. Garter snakes with their vomeronasal ducts sutured closed did not respond differentially to earthworm extract and water under these test conditions. Thus their ability to discriminate earthworm extract from water in this bioassay was dependent upon a functional vomeronasal system. Earthworm extract retains its biological activity after boiling at 100 degrees C for 15 minutes and after lyophilization. Its effectiveness is not altered by changes in pH. Snakes continued to respond differentially to extracts with pH 2, 5-6 or 11. Chloroform extractions of the acid, neutral and alkaline earthworm extract yielded activity primarily in the water layer. The small amount of activity in the chloroform layer was removed by use of a drying agent. Bradford dye-binding tests indicated the presence of protein in the active fractions.

Animals↗
PubMed1982

Neurogenesis in the vomeronasal epithelium of adult garter snakes. 1. Degeneration of bipolar neurons and proliferation of undifferentiated cells following experimental vomeronasal axotomy.

Postnatal cell proliferation, presumably for the purpose of neuronal replacement, was demonstrated in the vomeronasal epithelium of adult garter snakes using experimental vomeronasal axotomy. The luminal supporting cell layer of the epithelium did not undergo mitosis, nor necrosis, but exhibited some morphological modifications following axotomy. The bipolar layer underwent progressive irreversible degeneration following denervation. Degeneration of neurons progressed initially from alteration of cellular ultrastructure, to gross distortion of neuronal shapes followed by disintegration and disappearance of necrotic neurons. Maximal depletion of neurons occurred two weeks following surgery. The columnar epithelium at that time was characterized by the presence of a cell-depleted zone located between the luminal supporting cell layer and the basal, undifferentiated (Ud) cell layer. This cell-depleted zone occupied 70-80% of each degenerated cell column. Regeneration of axotomized neurons did not occur. The basally located, Ud cells exhibited no changes indicative of necrotic processes, but underwent active cell proliferation following axotomy. Changes in proliferative properties in the Ud cell layer were temporally related to the degeneration of the neuronal cell layer following nerve lesion. The Ud cell proliferation rate was slower than the rate of Bp cell degeneration. Proliferating Ud cells in the denervated epithelium may serve as the source of reconstituted vomeronasal bipolar neurons.

Afferent Pathways↗
PubMed1982

Neurogenesis in the vomeronasal epithelium of adult garter snakes. 2. Reconstitution of the bipolar neuron layer following experimental vomeronasal axotomy.

Postnatal neurogenesis and reconstitution of the neuronal layer of the vomeronasal epithelium have been demonstrated in adult garter snakes following vomeronasal axotomy. Two weeks following axotomy the vomeronasal epithelium was depleted of its bipolar layer but the basal, undifferentiated cells were actively proliferating. In subsequent weeks the undifferentiated cell layer continued to increase its cell population through mitosis and began to occupy the neuron-depleted zone of the receptor cell column. Four weeks following axotomy the denervated epithelium contained an expanded Ud cell layer which occupied the basal one-half to two-thirds of the receptor cell column. The cells at the base of the expanded Ud cell layer were morphologically similar to Ud cells in a normal epithelium whereas the cells at the apex of the columns resembled normal differentiating neurons. A few necrotic cells could still be detected within the apical, cell-depleted zone. By the eighth post-operative week the receptor cell column was fully occupied with cells formed as a result of Ud cell proliferation. The most apical cells, 6-10 cells deep, were morphologically similar to normal bipolar neurons with a dendritic process reaching the lumen of the VN organ. The remaining cells were morphologically similar to normal differentiating or Ud cells. Sixteen weeks following axotomy a larger portion of cells in the receptor cell column were fully differentiated bipolar neurons. The Ud cell population was reduced and, as in the normal epithelium, occupied only the basal portion of each receptor cell column. The regenerated neurons of the VNO were capable of synthesizing and transporting macromolecules to the telencephalon as demonstrated by autoradiography following intraepithelial injections of [3H]proline. Newly formed axons terminated in the accessory olfactory bulb within 8 weeks following axotomy. These results support the view that the basal Ud cells were the source of neurons in the regenerating vomeronasal organ and demonstrate a dynamic process of neuronal proliferation, differentiation and maturation in the denervated vomeronasal epithelia of adult garter snakes.

Afferent Pathways↗
PubMed1982

Urinary mutagenicity in occupational exposure to mineral oils and iron oxide particles.

Mutagenicity in the urine of workers occupationally exposed to mineral oils and iron oxide particles and age matched workers only exposed to mineral oils was investigated using the Salmonella/mammalian microsome assay. Both groups of workers included smokers and non-smokers. Mutagenicity was significantly higher in the group of workers exposed to both mineral oils and iron oxide particles, the statistical significance of the difference being similar to that found when total non-smokers were compared with total smokers irrespective of occupational exposure. When only non-smokers of both groups of workers were compared, the extent of mutagenicity in the urine of workers exposed to iron oxide particles was still significantly higher, suggesting that smoking did not exhibit a significant enhancing effect on urinary mutagenicity of workers exposed to mineral oils and iron oxide particles, but instead seemed to enhance urinary mutagenicity similarly in both groups of workers. Whether or not this conclusion can be drawn may depend, among other factors, on the variability of the Ames assay. To cope with this particular problem, the possible usefulness of a mutagenicity factor is discussed.

Environmental Exposure↗
PubMed1982

Late events in T4 bacteriophage DNA replication. III. Specificity of DNA reinitiation as revealed by hybridization to cloned genetic fragments.

Through the use of the technique of hybridization to cloned genes, the site specificity of the reinitiation of T4 DNA replication was examined at late times after infection, when a large amount of DNA had accumulated in the infected cell. Replication was examined under two conditions; (i) when there was recombination but the repair of the recombinants was inhibited, and (ii) when recombination was followed by covalent joining. When no covalent repair of recombinant was allowed, reinitiation occurred in the areas known to be also involved in the initiation of replication of the parental molecule: thus late reinitiation, if covalent joining is prevented, is site specific. When there was covalent joining, reinitiation displayed no apparent site specificity. The results are discussed in light of the possibility that at late times after infection recombinant intersections act as primers. The similarity of the model proposed to the "break-and-copy" model for lambda phage and the fitness of the proposed model to the genetic phenomena described by others are emphasized.

Base Sequence↗
PubMed1982

Laboratory observations of aggregative behavior of garter snakes, Thamnophis sirtalis.

A laboratory model of garter snake aggregation behavior is described. Snakes tested in groups of eight established preferred shelter locations and reliably returned to these locations as a group or as individuals when the test aquaria were left undisturbed between trials. When the aquaria were cleaned and the contents were replaced on each trial, preferred shelter locations were not established over trials; however, the snakes were found under shelters in large aggregates more frequently than would be expected by chance. It appears that the snakes deposit cues in the apparatus that are subsequently used to return to preferred locations. Manipulations of various objects in the test arena strongly indicated that the relevant cues are deposited on the paper underlying the preferred shelter.

Animals↗
PubMed1982

Laboratory observations of aggregative behavior of garter snakes, Thamnophis sirtalis: roles of the visual, olfactory, and vomeronasal senses.

Two experiments were conducted to determine (a) whether male garter snakes (Thamnophis sirtalis) require a functional vomeronasal or olfactory system to return to previously preferred shelter locations and (b) the sensory modalities used by snakes to aggregate in the absence of previously deposited chemical cues. In Experiment 1, snakes with vomeronasal nerve lesions did not return to previously preferred shelter locations when tested individually. However, when tested with a group that included "control" animals, they returned to previously preferred shelters. The shelter-selection behavior of snakes with olfactory nerve lesions improved postoperatively, whereas the behavior of animals with sham lesions was unchanged. In Experiment 2, snakes were tested for aggregation in aquaria in which the substrate and other contents were cleaned between trials. After blindfolding or after olfactory nerve cuts, snakes aggregated at normal levels. When the snakes' vomeronasal ducts were sutured closed, aggregation scores were significantly depressed, although two of the three groups with vomeronasal duct sutures did aggregate just above chance levels. These studies indicate that use of chemical signals by garter snakes in shelter selection and aggregation is mediated by the vomeronasal system and that neither the olfactory nor the visual system is critical for these behaviors.

Animals↗
PubMed1981

Aerobic bacterial oral flora of garter snakes: development of normal flora and pathogenic potential for snakes and humans.

Garter snakes that are used for scientific laboratory studies or kept as exotic pets often become ill and die early in captivity. They may also act as reservoirs of potential human pathogens or transmit infection to man. A total of 126 strains of aerobic and facultative bacteria, most potential human and snake pathogens, were isolated from 82 garter snake oropharyngeal cultures. Coagulase-negative Staphylococcus species were the most common species isolated. Acinetobacter calcoaceticus var. anitratus, Hafnia alvei, Arizona hinshawii, Salmonella species, Shigella species, Klebsiella oxytoca, and Pseudomonas aeruginosa were among the potential pathogens isolated. The spectrum of bacteria with potential for causing oral and pulmonary infections in garter snakes is greater than has been previously appreciated. Garter snakes should also be considered reservoirs of human pathogens, and appropriate precautions should be taken by laboratory personnel and pet owners.

Aerobiosis↗
PubMed1981

Remanent magnetic fields for measuring particle retention and distribution in the lungs.

A relatively inexpensive method for the noninvasive in vivo detection of ferrimagnetic particles within the lungs of a large laboratory animal, viz., the donkey, is described. The particles were neutron activated prior to inhalation, which permitted a comparison of two different retention measurements for the same particles, i.e., a well-characterized radiological-detection method concurrent with the newer magnetic-field technique. The long-term clearance of the particles from the lung was monitored in terms of the reduction in initial remanent field following magnetization, and the reduction in gamma-ray flux reaching the collimated scintillation detectors. Comparison of the measurements confirmed that the reduction of the initial remanent-field values with time was due to particle clearance rather than a change of the iron state to a nonmagnetic form. This validates previous reports that particle clearance studies can be performed using remanent magnetic-field measurement techniques. However, remanent magnetic-field measurements require careful design and interpretation, since they are highly sensitive to the distribution of the particles within the effective viewing field.

Aerosols↗
PubMed1980

Scanning electron microscopic studies of the surface morphology of the vomeronasal epithelium and olfactory epithelium of garter snakes.

Fixed vomeronasal and olfactory epithelia from normal adult garter snakes were microdissected, fractured, and examined with a scanning electron microscope. The method permits a detailed comparative study of the structural organization and morphological characteristics of the constituent cells of the vomeronasal and olfactory epithelia. Despite similarities in the nomenclature of the constituent cells in both epithelia, significant differences exist in their surface morphology. A unique columnar structure composed of non-neuronal elements is present in the vomeronasal epithelium. These columns house the bioplar neurons and undifferentiated cells. Such a columnar organization is absent in the olfactory epithelium. In vomeronasal epithelium the bipolar neurons possess microvillous terminals at their dendritic tips, while the dendritic tips of the bipolar neurons of the olfactory epithelium possess cilia. Vomeronasal supporting cells are covered with microvilli, while olfactory supporting cells are covered with cytoplasmic protuberances in addition to the microvilli. In the vomeronasal epithelium the pear-shaped neurons have a grossly smooth surface and are organized into clusters, while in the olfactory epithelium the elliptical bipolar neurons are spinous, aligned side-by-side and interdigitate. The basal (undifferentiated) cell layer in the vomeronasal epithelium has a high packing density and is composed of several layers of irregularly shaped cells. In the olfactory epithelium the basal cell layer is loosely organized and composed of a single layer of oval cells. This information on the three-dimensional cell structure of both epithelia provides a basis for experimental observations on changes in morphology of the bipolar neurons during genesis, development, maturation, degeneration, and regeneration in postnatal, adult animals.

Animals↗