Morphology, physiology, and homology of the N-cell and muscle receptor organs in the thorax of the crayfish Cherax destructor.

The serial homology of arthropods, together with our ability to identify individual neurons from segment to segment, and from animal to animal, provides opportunities for studying the changes wrought by natural selection on specific neural elements when functional requirements change in different parts of the trunk. Using this concept as a guide, we studied the morphology and physiology of the thoracic N-cells and muscle receptor organs (MROs) of the crayfish Cherax destructor for evidence of serial homology and functional plasticity. Methylene blue staining, together with anterograde and retrograde filling with cobalt through cut axons, revealed the morphology of the receptors, disposition of their endings, and the pathways of their axons from receptor to ganglion. The seventh thoracic segment has tonic and phasic MROs with receptor muscles in parallel with different heads of the deep thoraco-abdominal extensor muscle. The sixth segment has a tonic MRO with a receptor muscle in parallel with one head of the abdominal abductor. These three receptors are typical MROs complete with accessory nerves. Thoracic segments 1-5 each give rise to one mechanosensory N-cell with a small cell body and long processes ramifying in a target muscle. N-cell 5 is associated with the abdominal-thoracic abductor muscle, and the other four are associated with parts of the epimeral attractor. The responses of N-cells 1-4 range from tonic to phasico-tonic and show a range of thresholds to passive muscle stretch and active contraction. Cobalt introduced into bundles of nerve fibers known to include N-cell axons reveals projections with branching patterns and morphology similar to abdominal MROs. The present findings, together with information on thoracic MROs and N-cells from other species, were tabulated according to neurotome. The clear pattern revealed leads us to propose that N-cells are derivatives of segmentally repeating MROs modified to monitor postural and locomotory movements in the less mobile thorax.

Selective expression of glionexin, a glial glycoprotein, in insect mechanoreceptors.

The distribution of a glial cell-associated glycoprotein, glionexin (GX), on sensory receptors of the adult cricket Acheta domesticus is described, using the monoclonal antibody 5B12 as an immunohistochemical probe. GX was previously shown to be widely distributed in the embryo and to persist in the postembryonic to adult central nervous system. Here we demonstrate that it is restricted in the adult periphery to three subclasses of mechano-receptor sensilla: large socketed hair mechanoreceptors, their associated campaniform sensilla, and chordotonal organs. GX was not detected in photoreceptors, chemoreceptors, or other mechanoreceptors. The pattern of distribution differs significantly within the three subclasses of mechanoreceptors. In the hair and campaniform receptors GX is restricted to the extracellular space among glial cells clustered around the axon hillock region, but in chordotonal organs it surrounds the scolopidium at the tip of dendrites. The highly restricted distribution of GX in the periphery suggests possible functions that include mechanical stability of the sensory apparatus and ionic homeostasis in the respective neuronal spike-generating regions. The developmental modulation of GX expression is taken to imply multiple functions for the molecule during the life of the insect.

A cryotomic method of hemisecting insect appendages for neuro-immunohistology.

A technique is described for longitudinally hemisecting small and often flexible appendages of arthropods, by embedding the material in frozen 30% sucrose which is wax-like in texture. The cleanly cut tissue is then amenable to immunohistochemical techniques since the problem of impenetrability of cuticle to antibodies is by-passed. The apparatus utilizes a simple temperature-regulated aluminium stage cooled by dry ice. Fixed, surcrose-infiltrated appendages are block-mounted on the stage, and cut with a razor blade during visual guidance using a dissecting microscope. A combination of hemisections and thick sections also can be prepared. This method has been used to demonstrate the expression of glionexin, a glial cell-associated glycoprotein, and ELAV, a neuronal cytoplasmic protein, in mechanoreceptor organs and sensilla of the cricket Acheta domesticus.

Characteristics of an avirulent Campylobacter jejuni strain and its virulence-enhanced variants.

The virulence of Campylobacter jejuni for 11-day-old chick embryos is associated with the ability to invade the chorio-allantoic membrane, to resist phagocytosis and to survive and proliferate in vivo. The pathogenicity of a well characterised avirulent C. jejuni strain was enhanced by passaging it intravenously and chorio-allantoically through chick embryos. The resulting isogenic variants had greatly increased ability to survive in vivo. In this study, the morphological and cell-surface characteristics of the avirulent parental strain were compared with those of the more virulent variants to determine whether pathogenicity was associated with one or more cell-surface constituents. Changes associated with the increased virulence of the two variants included alterations in cultural and cellular morphology, loss of flagella, expression of a new outer-membrane protein, alterations in cell-surface carbohydrates and decreases in cell-surface hydrophobicity.

Virulence of Campylobacter jejuni for chicken embryos is associated with decreased bloodstream clearance and resistance to phagocytosis.

The 11-day-old chicken embryo has been shown to be a useful animal model for comparing the virulence of human isolates of Campylobacter jejuni. Virulence in this system is associated with the ability to invade the chorioallantoic membrane and to survive and proliferate in vivo. In this study, the survival and multiplication of C. jejuni in the embryonic host was investigated. It was possible to enhance the virulence of a relatively avirulent C. jejuni strain by passaging it intravenously through the embryos. The resulting isogenic variants demonstrated enhanced abilities to survive in vivo but were still unable to invade when inoculated onto the chorioallantoic membrane. The bloodstream clearance of C. jejuni was studied, and virulent, but not avirulent, strains persisted and multiplied both in the bloodstream and in embryonic liver. Virulent strains also were cleared significantly more slowly from the bloodstream of adult BALB/c mice after intravenous challenge than were avirulent strains. C. jejuni strains which were cleared slowly in vivo were also ingested slowly in vitro by mouse peritoneal macrophages. Clearance studies in mice pretreated with cobra venom factor demonstrated that opsonization by serum complement was not a prerequisite for clearance of campylobacters from the murine bloodstream.

Dysphagia with head injury.

This retrospective study was conducted: (1) to establish the incidence of dysphagia with head injury, (2) to demonstrate the capabilities of videofluorography (VFG) in identifying the common areas of swallowing dysfunction, and (3) to demonstrate the dysphagia management advantages of the VFG. Nine patients (30%) were found to have significant swallowing problems among 30 patients admitted to the Head Injury Program, Erie County Medical Center, Buffalo, NY in 9 months. These nine patients represent 4.5% of all head-injured patients admitted. The most common swallowing problems demonstrated by videofluorography barium swallow were prolonged oral transit and delayed swallowing reflex; each occurring in 87.5% of eight cases. The study revealed a high correlation between swallowing dysfunction and prolonged hospitalization. Serial VFGs document improved swallowing function, and indicate when relatively safe cessation of nasogastric tube feedings can be achieved. This may permit shorter hospitalization.

Proprioceptive inputs to nonspiking local interneurons contribute to local reflexes of a locust hindleg.

Local reflexes of a leg of the locust Schistocerca gregaria (Forskal) can be elicited by selective stimulation of a proprioceptor (the femoral chordotonal organ) at the femorotibial joint. Motor neurons are either excited or inhibited, so that a coordinated reflex response of a leg results. At the same time, some nonspiking local interneurons are either excited or inhibited by the inputs from these proprioceptive afferents. Altering the membrane potential of an individual, nonspiking interneuron can either increase or decrease the response of the participating motor neurons to the proprioceptive stimulus and thereby alter the gain of the reflex. To determine the pathways, and to understand the role of the nonspiking interneurons in mediating these reflex effects, recordings were made simultaneously from these interneurons and afferent neurons. The excitation of a particular nonspiking local interneuron is produced monosynaptically by the afferent neurons. Chemically mediated EPSPs consistently follow sensory spikes with a latency that is the same as that for the known parallel, direct connections made by these sensory neurons with motor neurons (Burrows, 1987a). The chordotonal afferents and the branches of the local interneurons project to the same regions of neuropil. In contrast, the simplest inhibitory pathway is disynaptic, involving spiking local interneurons. The afferents make direct excitatory connections with some of these spiking interneurons, which then make direct inhibitory connections with a nonspiking interneuron. Interactions between the local interneurons add to the complexity of the pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of iron on growth, morphology, outer membrane protein composition, and synthesis of siderophores in Campylobacter jejuni.

Three human isolates of Campylobacter jejuni were grown in a biphasic culture medium with and without the addition of a synthetic chelator to induce iron limitation. Cells grown in low-iron medium exhibited slower growth rates and altered cellular morphology. Increased numbers of longer, more filamentous forms were seen in Gram-stained smears. Three proteins, with apparent Mrs of 82,000, 76,000, and 74,000, were consistently present in the outer membrane of cells grown in low-iron medium. At least one of these proteins (76,000 to 74,000) was exposed on the cell surface. A bioassay was used to look for the production of siderophores by these and other strains of C. jejuni. Seven of 26 strains tested produced detectable amounts of siderophores. Growing strains at 42 degrees C failed to suppress siderophore synthesis or to alter the outer membrane protein profiles of iron-starved cells. The ability of three strains to utilize exogenously supplied siderophores for growth in low-iron medium was also examined. All three strains were able to utilize enterochelin and ferrichrome, but none utilized aerobactin, rhodotorulic acid, or desferrioxamine B. The effect of iron on the virulence of C. jejuni for 11-day-old chicken embryos inoculated via the chorioallantoic membrane was also determined.

The chicken embryo as a model for campylobacter invasion: comparative virulence of human isolates of Campylobacter jejuni and Campylobacter coli.

Eleven-day-old chicken embryos were used to compare the relative virulence of minimally passaged human isolates of Campylobacter jejuni and Campylobacter coli. Graded doses of bacteria were inoculated onto the chorioallantoic membrane, and 50% lethal doses were calculated at 72 h postinfection. Strains varied markedly in their ability to invade the chorioallantoic membrane and kill the embryos. The 50% lethal doses varied by about 6 logs for 25 strains of C. jejuni, and by 2 logs for 5 strains of C. coli. Although both outbred and inbred embryos were employed in the study, the latter were found to be more susceptible to infection with most strains. All isolates were screened for plasmid DNA, but there was no apparent relationship between plasmid content and virulence of strains for the embryos. Neither could virulence be associated with the production of siderophores by the strains. The ability of selected strains of C. jejuni to invade the liver of embryos was also studied. The number of campylobacters culturable from the liver was found to be inversely related to the 50% lethal dose of the strain. By inoculating 11-day-old embryos intravenously, it was possible to demonstrate that a strain of C. jejuni which was poorly virulent after chorioallantoic inoculation was relatively noninvasive. Invasiveness alone, however, could not fully account for the lethality of two highly virulent strains of C. jejuni administered by the intravenous route. Finally, there was no correlation between motility and virulence in this model system.

The role of gut flora and animal passage in the colonisation of adult mice with Campylobacter jejuni.

Adult female mice were given drinking water containing tobramycin 0.05 mg/ml for a week. After a further day without antibiotic they were inoculated intragastrically with one of three strains of Campylobacter jejuni. Colonisation of the gastrointestinal tract was judged by culturing faecal pellets. Tobramycin-treated mice differed from untreated animals in that many more of them discharged infected pellets, and their pellets contained 5- greater than 300 times more campylobacters. Colonisation could be prevented by inoculating the tobramycin-treated animals intragastrically, 24 h before the administration of C. jejuni, with a bacterial suspension prepared from normal faecal pellets. Coliforms, lactobacilli, the two in combination, and anaerobes grown from faecal pellets were not effective in preventing colonisation. Most of the C. jejuni were found in the large intestine of the tobramycin-fed mice. The persistence of colonisation of six dams nursing C. jejuni-infected offspring ranged from 10 to at least 29 weeks.

Elicitation and abrupt termination of behaviorally significant catchlike tension in a primitive insect.

Sustained steady contractural or catchlike tension (CT) occurs in the metathoracic extensor tibiae muscle of the primitive insect the weta (Orthoptera: Stenopelmatidae) during its characteristic leg-extension defense behavior or following leg-position conditioning. Similar action occurs occasionally in semi-intact preparations and is abruptly turned off by a single peripheral inhibitory impulse. These phenomena were reproduced routinely by first infusing saline containing 10(-8) M (or stronger) octopamine into the muscle for 12 min, and then stimulating the slow excitatory motor neuron SETi with a brief burst. Direct stimulation of the dorsal unpaired median neuron, innervating the extensor tibiae (DUMETi) prior to SETi stimulation, also led to CT. Both octopamine and DUMETi markedly enhanced the tension developed in response to a burst of impulses in SETi.

Defense posture and leg-position learning in a primitive insect utilize catchlike tension.

The capability for conditioning of leg position, using loud sound as an aversive natural reinforcement, was examined in a primitive New Zealand insect, the weta (Orthoptera: Stenopelmatidae). Electromyographic recordings were made during the conditioning. A majority of wetas tested came to occupy stably a metathoracic tibial position window, coupled to turning off the sound, set in either flexion or extension away from the preferred rest position. Steady tensions of up to 7 g in extension and 5 g in flexion were produced. However, no electromyographic activity accompanied the tension. It is concluded that the insects are using a peripheral catchlike mechanism to adjust posture.

Intestinal colonization of neonatal animals by Campylobacter fetus subsp. jejuni.

Neonatal mice (2.3 to 2.8 g) were inoculated intragastrically with different human isolates of Campylobacter fetus subsp. jejuni. At weekly intervals thereafter, mice were sacrificed and dilution plate counts were performed on segments of the gastrointestinal tract. Mice were uniformly colonized by some strains for 2 weeks, whereas other strains were being cleared at that time. One strain (BO216) persisted in some mice for 3 weeks. The greatest number of organisms (10(7)) was recovered from the cecum and large intestine. The small intestine had from 10(2) to 10(5) colony-forming units. Colonization of the stomach was not found consistently. One strain killed 13% of the infected mice. Deaths occurred between 1 and 5 days postinfection. Two other strains killed a smaller percentage of challenged animals, and two additional strains killed none. Retarded weight gain was noticed in some, but not all, of the infected mice. The intestines of neonatal rats and rabbits were colonized much the same as those of mice, whereas hamsters were resistant to colonization. Preweanling mice, up to about 6.5 to 7.0 g, could be colonized with C. fetus subsp. jejuni after intragastric challenge, but weanling mice of larger weight (9.8 g) and young adult mice (18.3 g) could not. Scanning electron photomicrographs of the lower ileum showed campylobacters in and below the dried mucous gel that lines the intestines. The use of this model for additional studies is discussed.

Persistence and spread of Candida albicans after intragastric inoculation of infant mice.

Infant mice have been shown previously to be a useful model for the study of gastrointestinal (GI) and systemic candidosis. In this study, the virulence of four strains of Candida albicans was compared in intragastrically inoculated infants and in adult mice inoculated intravenously. The four strains differed in their ability to kill both infant and adult mice. A smaller inoculum was required to kill adult mice inoculated intravenously. Neonates could not be inoculated intravenously. The ability of the strains to spread systemically from and to persist for long periods of time in the digestive tract was also examined in intragastrically inoculated infants. The yeast cells spread to liver, lungs, kidneys, and spleen within 30 min postinoculation. Yeast were not detectable in the lungs or in blood from the pleural cavity up to 15 min post-inoculation, thus making it unlikely that systemic spread resulted from faulty inoculation or from aspiration. The region where C. albicans crossed the GI tract of infant mice was visualized histologically in the upper third of the small intestine. The four strains varied in their ability to persist for long periods in the GI tract, in the rate at which they appeared systemically, and in ability to kill infant mice. Three of the four strains colonized the gut for up to 10 weeks postinoculation without use of any compromising agents.

Structure of the auditory system of the weta Hemideina crassidens (blanchard, 1851) (Orthoptera, Ensifera, Gryllacridoidea, Stenopelmatidae). 1. Morphology and histology.

The morphology and histology of the tibial auditory system of the New Zealand weta, Hemideina crassidens, are described. The groups of acoustic sensilla conform closely to the subgenual organ, intermediate organ and crista acoustica of the Tettigoniidae. Each prothoracic tibia bears two thick (40-100 micrometers) tympana of approximately equal size divided into two distinct zones. The tracheae of the prothoracic legs are connected across the midline by a transverse commissure and by a chiasma between the ventral longitudinal trunks. No expanded vesicle ("vesicula acoustica") is associated with the spiracle. The anterior and posterior tracheae are divided into three distinct regions within the tibia: (1) a bulbous proximal posterior inflated chamber, (2) the tympanal vesicles to which the tympana attach, and (3) an elongate distal posterior inflated chamber. The pattern of innervation in the tympanal region is similar to that of gryllids as is the central projection of the tympanal nerve. The subgenual organ, which contains ca. 50 sensilla, forms an acute angle with the wall of the leg. The intermediate organ contains ca. 19 sensilla forming an arc against the anterior wall of the leg. The crista acoustica contains ca. 50 sensilla aligned in a gelatinous matrix along the dorsal surface of the anterior tympanal vesicle. Each dendrite projects distally, then is reflected proximally and dorsally to end in a scolopale embedded in an attachment cell. The attachment cells are stellate in the proximal portion of the crista, but distally they occur as parallel lamellae. The weta ear is compared with those of other Orthoptera.

Antibiotic susceptibility testing of Bordetella pertussis.

A tube dilution test to evaluate the effectiveness of antibiotics against Bordetella pertussis is described. Five B. pertussis strains, including a well-characterized research strain and four fresh clinical isolates, were tested with several antibiotics. Erythromycin showed the highest in-vitro activity of the antibiotics tested. A concentration of 0.12 microgram/ml was bacteriostatic for all strains, while 2 microgram/ml was bactericidal. Minimal inhibitory and minimal bactericidal concentrations for ampicillin by tube tests were found to be higher than values previously reported for agar plate tests.

The effect of cyproterone acetate on serum testosterone, LH, FSH, and prolactin in male sexual offenders.

The anti-androgen, cyproterone acetate, was administered in a dose of 100 mg/day to eight adult male sexual offenders for 21-31 days. Serum testosterone fell to subnormal levels within 7 days and remained low for 6-28 days after treatment was stopped. The fall in testosterone was accompanied by a fall in serum luteinizing hormone (LH) and follicle stimulating hormone (FSH), and a rise in serum prolactin. All subjects experienced a decrease in libido and in frequency of masturbation. The probable mechanisms of action of cyproterone acetate are discussed, as is its potential role in the management of sexual offenders. These studies suggest that measurement of serum testosterone could be used as an index of compliance in sexual offenders treated with cyproterone acetate who are released on parole.

Variability in derivative strains of Bordetella pertussis.

Bordetella pertussis strain UT25 was isolated on Bordet-Gengou(B-G) agar from a child with whooping cough in 1977. Derivative strains were isolated from UT25 by serial passages on Trypticase Soy Agar (TSA) containing blood,followed by serial passages on plain TSA. At passage 69, UT25 was subcultured in parallel on TSA and B-G. For experiments, strains were grown in defined liquid medium, adjusted to a standard turbidity, and tested in parallel. Tests were performed to detect changes in immunogenicity, production of dermonecrotic toxin, histamine sensitizing ability, serologic properties, infectivity for mice by the intranasl route, production of adenylate cyclase, patterns of outer membrane proteins. Notable changes occurred in the properties of UT25 at passage 16, just when stable growth on blood-fresh medium was established. After 5 additional passages on TSA, however, the strain resembled the original isolate. At about passage 45, biological activity began to decline, and by passage 60 most biological activities were sharply diminished or undetectable. No recovery of biological activity was observed during a further 15 passages on TSA. Strains derived from the sixty-ninth passage of UT25, after passage on B-G for 5 subcultures, showed partial recovery of biological activity. Ten additional subcultures on B-G yielded strains which showed even higher biological activity. Fluorescent antibody staining confirmed that all strains studied were B. pertussis, and maintained reactive surface antigen(s), in spite of loss of agglutinability in specific antiserum.

Effects of fatty acids on growth of Bordetella pertussis in defined medium.

The effects of saturated and unsaturated fatty acids on the growth of Bordetella pertussis strain 114 in defined medium were tested. Individual fatty acids were found to be either inhibitory or stimulatory to growth, depending on concentration. Myristic (C14), pentadecanoic (C15), and palmitic (C16) acids were the most inhibitory saturated fatty acids tested. B. pertussis 114 was extremely sensitive to the unsaturated fatty acids oleic (C18; cis-9), elaidic (C18; trans-9) and petroselinic (C18; cis-6).