Biomedical subjects

R J O'Connell

Publications and source records attributed to R J O'Connell.

At least 19 recordsLinked to original sources

PubMed2001

Induction of c-fos in hamster accessory olfactory bulbs by natural and cloned aphrodisin.

Male hamsters were exposed to the female pheromone, aphrodisin (APH), its cloned protein backbone (rAPH), and the homologous lipocalin, beta-lactoglobulin (beta-LG). Of these, only APH elicited mating behavior. Enhanced c-fos protein was found in the nuclei of neurons in the accessory olfactory bulb (AOB) after exposure to these stimuli. Relative to beta-LG, both rAPH and APH produced significant increases in AOB labeling. The modest labeling elicited by rAPH was evenly distributed, but the heavier staining elicited by APH was concentrated in the caudal region of the AOB. Thus, pheromone receptor neurons in the basal compartment of the vomeronasal epithelium, which project to the caudal region of the AOB, may respond to APH and provide the input which drives mating behavior.

Animals↗

PubMed2000

Responses of olfactory receptor neurons in Utetheisa ornatrix to gender-specific odors.

We recorded the electrophysiological responses of individual olfactory receptor neurons in sensilla trichodea on the antennae of adult arctiid moths, Utetheisa ornatrix, to stimulation with volatiles associated with both sexes. All trichoid sensilla contain at least two receptor neurons, each with distinct action potential amplitudes and waveforms, that respond dichotomously to male and female odors. Although, neither female neuron responds to extracts of coremata or the male-produced pheromone hydroxydanaidal, they do respond in a gender-specific manner to the volatiles emanating from whole pupae, hemolymph, thoracic froth, and adult animals of several ages. Thoracic froth, which contains pyrrolizidine alkaloids, is thought to play a role in defense. Froth from moths reared on diets, with or without added pyrrolizidine alkaloids, were equally effective in eliciting gender-specific patterns of response. Male trichoid receptor neurons respond to these same materials with similar patterns of activation. These receptor neurons provide information about substances, which we have termed "gender odors," that are persistently emitted by nearby animals. These substances do not appear to be the same as those already known to be involved in defense or the sexual dialog between individuals.

Animals↗

PubMed2000

Immunomagnetic purification of Colletotrichum lindemuthianum appressoria.

We developed a method to purify appressoria of the bean anthracnose fungus Colletotrichum lindemuthianum for biochemical analysis of the cell surface and to compare appressoria with other fungal structures. We used immunomagnetic separation after incubation of infected bean leaf homogenates with a monoclonal antibody that binds strongly to the appressoria. Preparations with a purity of >90% could be obtained. Examination of the purified appressoria by transmission electron microscopy showed that most had lost their cytoplasm. However, the plasma membrane was retained, suggesting that there is some form of attachment of this membrane to the cell wall. The purified appressoria can be used for studies of their cell surface, and we have shown that there are clear differences in the glycoprotein constituents of cell walls of appressoria compared with mycelium.

Animals↗

PubMed1998

Expression cloning of a fungal proline-rich glycoprotein specific to the biotrophic interface formed in the Colletotrichum-bean interaction.

The monoclonal antibody, UB25, recognises a glycoprotein specifically located at the biotrophic interface formed in the Colletotrichum lindemuthianum-bean interaction. The antibody labels the walls of intracellular hyphae and the interfacial matrix which separates them from the invaginated host plasma membrane. In Western blots, UB25 recognises a ladder of bands which are multiples of M(r) 40.5 kDa. A full length cDNA encoding the glycoprotein recognised by UB25 has been isolated by expression cloning and designated CIH1 (Colletotrichum Intracellular Hypha 1). In vitro transcription/translation of CIH1, and transfection of mammalian COS cells, showed that UB25 recognized the expressed product in both procedures confirming that the clones isolated were true positives. Southern analysis of bean and C. lindemuthianum genomic DNA indicated that the CIH1 glycoprotein is fungally encoded and Northern analysis showed that it is only expressed in planta. Analysis of the deduced amino acid sequence of CIH1 indicates the presence of an N-terminal signal sequence and two possible sites for N-glycosylation. The N-terminal domain of the mature protein is rich in proline and contains several short repetitive motifs. CIH1 is thus a fungal proline-rich glycoprotein which appears to form a cross-linked structure in planta and, as such, resembles plant cell wall proline- and hydroxyproline-rich proteins. Possible functions for the CIH1 protein in the establishment and maintenance of biotrophy are discussed.

Amino Acid Sequence↗

PubMed1996

Pheromone-induced second messenger signaling in the hamster vomeronasal organ.

Compounds present in estrous hamster vaginal discharge modulate male attraction and mounting behavior. These compounds are differentially processed by chemosensory neurons in the main olfactory epithelium (MOE) and vomeronasal organ (VNO). The transduction cascade responsible for this processing is unclear in the VNO, although studies of the MOE suggest that the second messengers cAMP or IP3 may be involved. Here we demonstrate that purified aphrodisin, a hamster mounting pheromone, modulates IP3 production in male VNO membranes without altering cAMP production. Aphrodisin does not alter the concentration of either second messenger in membranes from the MOE. These results confirm the specificity of the VNO in the processing of mounting pheromones and establishes the importance of IP3 cascades in mammalian reproductive behavior.

Animals↗

PubMed1996

Electrophysiological responses from receptor neurons in mosquito maxillary palp sensilla.

We recently completed an electrophysiological study of the receptor neurons found in the sensilla basiconica on the maxillary palps of mosquitoes. Our results describe a class of receptor neurons whose properties could provide the afferent input required for some aspects of CO2-modulated host-locating behaviour. First, these neurons have apparent thresholds (150-300 ppm) which are at, or below, the concentration of CO2 (300-330 ppm) normally reported for ambient air. Second, their concentration-response functions are steep, such that small (50 ppm) fluctuations in concentration elicit reliable changes in activity. Third, they behave like absolute CO2 detectors in that their ability to respond to step increases in CO2 concentration is little influenced by the background concentration of CO2. And fourth, a linear extrapolation of the observed response function to the levels that might be expected near vertebrate hosts suggests that these neurons have sufficient dynamic range to cover those CO2 concentrations that should be encountered during a large portion of the behaviour likely involved in host location. The mosquito CO2 receptor neuron thus has an appropriately low threshold and a steep concentration-response function, it is not desensitized by ambient levels of stimulation, and it has a dynamic range appropriate for the distribution of CO2 concentrations expected in the environment. In addition, this sensillum contains two other receptor neurons, neither of which respond to CO2. One of these neurons responds to stimulation with very low doses of another behaviourally relevant compound, 1-octen-3-ol.

Aedes↗

PubMed1996

Semantic-free scaling of odor quality.

The validity of the odor quality reports given by naive human subjects is often questionable. On the one hand, social conventions can influence the labeling of odorants, especially those that have putrid or uncommon odor qualities, and on the other, semantic differences exist for odor descriptors among individuals. We are interested in the individual differences in the quality reports elicited by two nominally putrid odorants, androstenone (AND) and pemenone (PEM). Here we sought to establish empirical support for the individual differences previously obtained in studies of their odor quality, using a nonverbal, semantic-free method of classification. Undergraduate volunteers sniffed a moderate concentration (390 microM) of PEM, rated its intensity, and provided a verbal odor descriptor. The subjects were then classified as PEM osmic (n = 42) if the quality report was putrid (rancid, urinous, sweaty), allosmic (n = 23), if the quality was nonputrid, and anosmic (n = 39) if no odor was detected. The subjects then sorted 15 odorants matched for intensity, five selected from each of three nominal odor quality types, into as many odor groups as they wished, as long as each group contained all of the compounds with similar odors. The number of times each odorant was paired with another was used as data for an independent multidimensional scaling with ALSCAL, for each class of subject. Three-dimensional solutions showed that this nonverbal, semantic-free scaling method produced odor classifications consistent with those found when each class of subject reported odor qualities from a defined list of quality descriptors. Cluster analysis of the MDS coordinates revealed that these solutions also retained the individual odor quality differences thought to be characteristic of osmic, allosmic and anosmic subjects.

Adult↗

PubMed1996

Pemenone and androstenone do not cross-adapt reciprocally.

Explorations of the qualitative and quantitative differences between the odors of pemenone (PEM), androstenone (AND) and isovaleric acid (IVA) show that they share a number of common perceptual characteristics. Among these are similarities in their odor quality and relative intensity ratings. PEM is also an efficient cross-adaptor and modulator of a subject's AND sensitivity. Here we evaluate the reciprocal efficacy of AND adaptation to alter the perceived intensity and quality of PEM, IVA and AND. Twenty-three people, including both those osmic and allosmic (n = 11) for the putrid odor quality of PEM, were tested. Following training in odor quality and intensity rating techniques, subjects sampled a selected substance for 2 min to obtain adaptation and then reported quality and intensity ratings for the three test stimuli. There was significant self-adaptation by PEM and IVA in all subjects, but self-adaptation by AND was only observed in the PEM-osmic subjects. AND did not cross-adapt PEM or IVA to any significant extent. Collectively, these results contrast with our earlier study in which PEM was an efficient cross-adaptor of AND. Here, AND was no more efficient than the control as an adapting substance for PEM, despite significant self-adaptation of PEM by itself. This lack of reciprocity in the effectiveness of PEM and AND as cross-adapters is not related to differences in odor intensity, as the PEM and AND concentrations were adjusted for each subject to elicit comparable intensity reports. These results support the notion that PEM, AND and IVA share certain perceptual characteristics, but interact differentially with three or more sets of perceptual channels that are now thought to result in a putrid odor quality.

Adaptation, Physiological↗

PubMed1995

Electrophysiological responses of receptor neurons in mosquito maxillary palp sensilla to carbon dioxide.

Sensilla basiconica on the maxillary palps of female Aedes aegypti contain a receptor neuron which produces a phasic-tonic pattern of action potential response to low concentrations (150-300 ppm) of carbon dioxide (CO2), a stimulus known to be involved with host seeking behavior. These receptor neurons respond reliably to small increments in CO2 concentration (e.g., 50 ppm). We were particularly interested in evaluating the possibility that the sensitivity to step increases in CO2 concentration could be modulated by alterations in the background levels of CO2, over a range which might be encountered during host-seeking behavior. We report here that the response (impulses/s) to a single pulse of a given concentration of CO2 appears to be independent of the background level of CO2, unless that level is equal to or greater than the concentration of the stimulus pulse. Females of other mosquito species, including: Anopheles stephensi, Culex quinquefasciatus, Culiseta melanura, and Aedes taeniorhynchus, also possess sensilla with receptor neurons that respond with comparable sensitivity to CO2 stimulation. However, there is much interspecific variation in both the external morphology of the maxillary palp and the distribution of sensilla along the palp. Male Ae. aegypti have morphologically similar sensilla which also contain a receptor neuron that responds to CO2.

Action Potentials↗

PubMed1995

Enhanced sensitivity to androstenone following regular exposure to pemenone.

The responses elicited by olfactory stimuli may be modified throughout an organism's life. For example, Wysocki et al. found that regular presentations of 5a-androst-16-en-3-one (androstenone) to anosmic subjects resulted in a graded increase in the perceived intensity of this substance in about half of their subjects (Wysocki et al., 1989). The increased sensitivity they observed appeared to be specific to the exposed odorant and was presumed to occur only in anosmic subjects. Here, we continue our explorations of the individual differences in olfactory capabilities among subjects initially classified by their ability to detect and identify the odor of the diastereoisomeric ketone, cis-4-(4'-t-butylcyclo-hexyl)-4-methyl-2-pentanone (pemenone) which shares with androstenone a pronounced urine-sweaty odor. We asked if regular pemenone exposure enhances the sensitivity of human subjects to pemenone, androstenone, isovaleric acid, or phenylethyl alcohol and, if shifts in threshold occurred, were they specific to particular odorants and classes of subject? Detection thresholds for the four substances were determined before and after 7-8 weeks of regular, biweekly, exposure to pemenone (n = 18 subjects) or a control substance (22 subjects). Significant decreases in threshold were seen in the experimental group, relative to the control group, for androstenone, but not for the other compounds evaluated. Neither gender nor initial pemenone osmicity significantly affected the frequency of subjects with enhanced sensitivity. These findings show that a subject's sensitivity to one odorant can be enhanced by exposure to another, chemically distinct compound.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Individual differences in the perceived intensity and quality of specific odors following self- and cross-adaptation.

Adaptation techniques have traditionally been employed in sensory physiology and psychology to characterize afferent pathways and to dissect the quantitative and, to a lesser degree, the qualitative aspects of perception. We continue to explore the individual differences in olfactory capabilities among subjects initially classified by their ability to detect and identify the diastereoisomeric ketone, cis-4-(4'-t-butylcyclohexyl)-4-methyl-2-pentanone (pemenone) which shares with 5 alpha-androst-16-en-3-one (androstenone) a pronounced urine-sweaty odor. Our previous studies of these and other compounds for which specific anosmias were said to exist revealed significant relationships between intensity scores and a corresponding clustering of the odor quality descriptors used to characterize these materials by subjects judged to be specifically anosmic for the urinous note. Here, we attempt to dissect the web of interactions which give rise to individual differences in perceived odor quality by evaluating the effects of self- and cross-adaptation on the intensity and quality reports elicited by pemenone, androstenone and four other odors in 18 human subjects including both pemenone-osmic and non-osmic (n = 6) individuals. Intensity and quality ratings for the six compounds were obtained before and after an adaptation sequence in which subjects sniffed a test odorant, pemenone or the diluent. For each odorant, intensity ratings under the different adapting conditions were compared by ANOVA. Self-adaptation was universal but cross-adaptation by pemenone was only found in the intensity ratings of androstenone. The intensity ratings of isovaleric acid, which shares the urinous note with pemenone and androstenone, were unaffected by pemenone adaptation. Most of the subjects judged to be osmic still reported a urinous odor quality for androstenone and isovaleric acid following pemenone adaptation. Except for shifts to the no-odor category, adaptation did not significantly alter the odor quality reports of osmic or non-osmic individuals. This suggests that the odor quality reports engendered by these substances are multidimensional and that compounds which share the same odor quality label may interact with different perceptual channels.

Adaptation, Physiological↗

PubMed1992

Temporal analysis of adaptation in moth (Trichoplusia ni) pheromone receptor neurons.

The temporal pattern of response in chemoreceptor neurons reflects both the temporal distribution of stimuli and the timing of signal transduction, action potential generation and propagation. Here we analyze the temporal characteristics of the responses elicited in pheromone receptor neurons by computer-controlled rectangular pulses of odorant. Extracellular recordings from the HS sensilla trichodea on the antenna of male Trichoplusia ni reveal the activity of two neurons: the "A" neuron, which responds to the major component of the female pheromone blend, (Z)7-dodecenyl acetate and the "B" neuron, which responds to (Z)7-dodecenol. "B" neurons were divided into two classes (HR, LR), based on the magnitude and temporal pattern of their response to (Z)7-dodecenol. Most "A" and HR "B" neurons responded to rectangular pulses of various durations (0.1-40 s) with an initial phasic burst (approximately 100 ms), followed by a slowly declining tonic component. At moderate and elevated pheromone doses, prolonged stimulation resulted in significant reductions in the tonic response levels (adaptation); stimuli of increasing duration effected greater adaptation. Most LR "B" neurons lacked a phasic response component and showed virtually no adaptation with prolonged stimulation. Pheromone receptor neurons may differ in both their spectral and temporal response properties which may provide the animal with additional sensory information for blend discrimination and spatial orientation in complex natural pheromone plumes. The potential functional value of adaptation in the moth pheromone communication system is discussed.

Action Potentials↗

PubMed1990

The modified Wilson osteotomy for hallux valgus.

The modified Wilson osteotomy for hallux valgus is a double oblique osteotomy through the metatarsal shaft. The distal fragment is displaced laterally and plantarward. The lateral displacement corrects the varus position of the metatarsal, while the plantar displacement prevents the distal fragment from tilting dorsally into a metatarsus elevatus deformity that could produce metatarsalgia. Seventy-four cases of hallux valgus treated by this method were reviewed five years postoperatively. Sixty-six cases (89%) were graded as satisfactory and eight (11%) as unsatisfactory. Roentgenographic analysis in 61 cases showed the operation had reduced the hallux valgus angle by an average of 15 degrees and the intermetatarsal angle by an average of 4 degrees. The operation shortened the first metatarsal by an average of 5 mm. Although this caused callosities on the forefoot, it did not produce metatarsalgia. The operation is technically uncomplicated and yields a high percentage of satisfactory results.

Adolescent↗

PubMed1989

Stimulus access to olfactory and vomeronasal receptors in utero.

Chemosensory systems in the mammalian nasal cavity are said to be functional before birth. Fluorescent beads (1 micron, diameter), injected into the amniotic fluid surrounding E18 mouse fetuses, were sought in serial frozen sections of E19 animals. Beads were found in all regions of the nasal cavity except for the lumen of the vomeronasal organ (VNO) where the receptor neurons of the accessory olfactory system (AOS) are located. Thin plastic sections through the rostral aspect of the E19 nasal cavity revealed that the VNO canals, which provide stimulus access to the AOS, are not patent. Thus, this chemosensory system can be excluded as a potential channel of chemosensory information for the mouse fetus.

Animals↗

PubMed1989

Sexual skin in rodents: an across body region, gender, and species analysis.

The effect of estrogen on the thickness of skin layers were examined in male and female mice and in female rats. Skin samples were taken from prepubertally castrated subjects given either 17 beta-estradiol or control implants. In agreement with an earlier report, the subcutaneous areolar tissue (SAT) of the lower back was nearly six times thicker, on average, in female mice with estradiol implants than in controls. Estrogen did not effect the thickness of the epidermis or dermis but preferentially increased the thickness of the deepest layer of the SAT. Analysis of skin samples from different body regions revealed that this response to estrogen was limited to the skin of the dorsum and was greatest in the area of the lower back. Castrated male mice with estradiol implants had markedly thicker SAT layers in the lower back region than controls. However, the magnitude of the response was less than that seen in estrogen-treated females. In contrast, the SAT in the lower back regions of castrated female rats with estrogen implants was not significantly different from controls, despite a pronounced uterine response to the hormone treatment. Thus, mice exhibit a species-specific, localized hypertrophy of one of the skin layers in response to estradiol. Mouse mating behavior involves the vigorous grasping and biting of the lower back region of the female. We suggest that at least one function of this estrogen-dependent hypertrophy is to protect the female from injury during mating.

Animals↗

PubMed1988

The contribution of olfactory receptor neurons to the perception of pheromone component ratios in male redbanded leafroller moths.

(Z)-11-tetradecenyl acetate (Z-11, 14:AC) must be in a 100:9 ratio with (E)-11-tetradecenyl acetate (E-11,14:AC) to produce maximal wing fanning and attraction in male redbanded leafrollers. Earlier electrophysiological studies had indicated that mixtures of these pheromone components elicited responses from olfactory receptor neurons that appeared to differ from those expected on the basis of the responses to the individual components. Here we evaluate whether the behavioral sensitivity to particular ratios of Z- and E-11,14:AC has a correlate in the response properties of olfactory receptor neurons. The stimuli included the ratios of Z- and E-11,14:AC used in earlier behavioral work plus several different mixtures of the seven components found in the pheromone blend, and equivalent amounts of the individual components. These stimuli were presented over a range of intensities to individual trichoid sensilla on the male antenna. In common with earlier results, the receptor neuron with the larger amplitude action potential responded most strongly to Z-11,14:AC, whereas the companion receptor neuron in the sensillum responded most strongly to E-11,14:AC. In contrast with earlier results, each receptor neuron responded exclusively to its own most effective stimulus, without regard to the presence of any other compound. They failed to respond uniquely to any of the other five compounds in the female pheromone blend, or to any of the tested combinations of these compounds. These minor components also failed to modulate the responses elicited in receptor neurons by appropriate ratios of Z- and E-11,14:AC. Thus, the responses of the two types of olfactory receptor neurons found in trichoid sensilla failed to show an optimum at the pheromone ratio known to elicit peak behavioral activity.

Action Potentials↗

PubMed1988

Are pheromones their own reward?

Hamster vaginal discharge (HVD) contains a variety of intersexual pheromones which are powerful promoters of male reproductive behavior. Males avidly investigate and then consume HVD from females or from artificial sources. We measured the reward strength of HVD and other sapid substances with operant techniques. The highest fixed ratio at which males would bar press, the break point, varied with the level of water deprivation and the volume of water reward. Break points for sucrose rewards, in undeprived animals, were higher than for water and varied with concentration. Water, vanillin and HVD solutions were comparable reinforcers irrespective of deprivation level. Sexual experience did not increase bar pressing for HVD rewards. Moreover, naive animals could not be trained to bar press for HVD. These results contrast with other evidence that HVD is highly palatable and challenge the notion that the pheromones present in it are innately rewarding. However, this conclusion may be mitigated by constraints on learning which limit the utility of operant techniques to evaluate the reinforcing properties of HVD.

Animals↗

PubMed1988

Bilateral simultaneous rupture of the quadriceps tendons. A report of four cases and review of the literature.

Four patients with bilateral simultaneous rupture of the quadriceps tendons were each older than 70 years of age. In the first patient the diagnosis was missed and one side was managed conservatively, while the other side was surgically treated. A combination of inadequate postoperative immobilization and the use of chromic catgut sutures probably caused failure of the repair, requiring revision surgery. The other three patients were treated by bilateral operative repair and had satisfactory results. Nonabsorbable suture material use and a minimum period of six weeks of postoperative immobilization are recommended.

Aged↗