Amphetamine withdrawal does not produce a depressive-like state in rats as measured by three behavioral tests

Administration of amphetamine (AMPH) can induce symptoms of psychosis in humans and locomotor sensitization in rats; in contrast, withdrawal from a period of AMPH intake is most often associated with symptoms of human endogenous depression. The aim of this study was to determine whether AMPH withdrawal produces a depressive-like state in rats. The present study examined the effects of withdrawal from an escalating-dose AMPH schedule (ESC; three daily injections over 6 days, 1-5 mg/kg, i.p.) and an intermittent-dose AMPH schedule (INT; one daily injection over 6 days, 1.5 mg/kg, i.p.) on animals' performance in three behavioral paradigms related to depression: the Porsolt swim test, the learned helplessness assay and operant responding for sucrose on a progressive ratio schedule. ESC and INT AMPH withdrawal had no effect on any of these tests or on stress responsiveness as measured by increased plasma levels of corticosterone (CORT) and adrenocorticotropin following the swim test, although basal CORT levels were higher in AMPH-withdrawn animals compared to controls. Finally, we confirmed the presence of locomotor sensitization for both AMPH schedules after 30 days of withdrawal. Our results suggest that the ability of AMPH withdrawal to produce symptoms of depression may not be evident in all behavioral screens for depressive symptoms in the rat.

Latent inhibition, but not prepulse inhibition, is reduced during withdrawal from an escalating dosage schedule of amphetamine

The enhanced locomotor and stereotypic responses of the rat to repeated amphetamine (AMPH) administration are considered to be an animal model of positive schizophrenic symptoms. In contrast, behaviors observed during withdrawal from repeated AMPH are believed to model depression or anxiety. In the present study, the authors tested whether AMPH withdrawal might also elicit behaviors consistent with animal models of schizophrenia, specifically, disruptions in latent inhibition (LI) of 2-way active avoidance and prepulse inhibition (PPI) of startle. Rats treated with escalating doses of AMPH (6 days, 1-5 mg/kg ip) or saline were tested for LI and PPI during withdrawal. LI was eliminated by prior AMPH treatment in rats tested at 4, 13, and 28 days of withdrawal. In contrast, PPI did not differ between AMPH and control groups. These results support an interrelationship between repeated-AMPH and LI-disruption, but not PPI-disruption, models of schizophrenia.

Increased conditioned fear response and altered balance of dopamine in the shell and core of the nucleus accumbens during amphetamine withdrawal

It has been suggested that neuroadaptations within the nucleus accumbens (NAC) dopaminergic (DA) projection contribute to the negative affect associated with psychostimulant withdrawal. The present study assessed the effects of amphetamine (AMPH) withdrawal on behavioral and NAC DA responses to conditioned fear stress. Animals injected with escalating-dose AMPH (1-5mg/kg, three injections/day, 6 days) or saline (SAL) acquired a tone-shock association on withdrawal day 3 and were tested for extinction of conditioned freezing to the tone on withdrawal day 4. Extracellular levels of NAC shell and core DA were monitored using in vivo microdialysis on both days. AMPH-withdrawn animals exhibited more conditioned freezing than SAL animals during both acquisition and extinction. During acquisition, DA increased more in the shell than the core of the NAC in both AMPH and SAL groups. During extinction to the tone, shell DA increased in SAL- but not AMPH-treated animals, whereas core DA activity was greater in AMPH than SAL animals. These data demonstrate that AMPH withdrawal alters the balance between shell and core DA transmission while increasing the behavioral expression of conditioned fear. Such drug-induced neuroadaptations in the NAC stress response may be involved in the exacerbation of negative emotions associated with drug withdrawal and stimulant-induced psychosis.

Selective responding of nucleus accumbens core and shell dopamine to aversively conditioned contextual and discrete stimuli

Dopamine transmission within the nucleus accumbens has been implicated as a neurochemical substrate of associative learning processes. It has been suggested that the acquisition of classically conditioned fear to a specific environment, or context, differs fundamentally from the development of conditioned fear to a discrete stimulus, such as a light or a tone. In this study, we assessed extracellular dopamine in the rat nucleus accumbens shell and core during the expression of a conditioned fear response. Animals were aversively conditioned to either a context or a tone and extracellular dopamine was measured in the nucleus accumbens shell and core by in vivo microdialysis over the next 2 days as animals were returned first to the conditioning chamber (day 1: context test), and subsequently as animals were again returned to the chamber and presented with the conditioned tone stimulus (day 2: tone test). Dopamine levels in the core were significantly higher in the Context-Shock group compared to the Tone-Shock group during the 30-min exposure to context while dopamine levels in the nucleus accumbens shell did not differ significantly during the context test between groups. In contrast, extracellular dopamine in the shell but not the core of Tone-Shock animals increased significantly during presentation of the tone. Dopamine in both the shell and core remained unchanged during the tone test in the Context-Shock groups.These data suggest distinct roles for shell and core dopamine transmission in the expression of a conditioned emotional response. While dopamine increased in the shell primarily during the presentation of a discrete tone conditioned stimulus, core dopamine responded more to a contextual conditioned stimulus. These results may reflect differences in either the type of information acquired or the salience of the learned associations which are formed to a context vs. a discrete tone cue.

Development of Onchocerca volvulus (Filarioidea: Onchocercidae) in the West African black fly Simulium yahense (Diptera: Simuliidae) in Liberia

Simulium yahense black flies infected with microfilaria of Onchocerca volvulus were kept in a defined insectary environment in Liberia, West Africa. A daily sample of infected flies was dissected for larvae developing in the thoracic muscles and examined for growth in stadial development. Microfilariae ingested by black flies transformed to the L1 larval stage without molting. Successive larval development included molting to the L2 stage and, finally, to the L3 stage, which was infective in humans. The cephalic cap, consisting of a laterally located hook and central stoma, occurs in the first larval stage. The caudal appendix and the laterally located anal opening are apparent in the L1 larva. In the L2 stage, the cephalic cap is lost and the large circular stoma becomes surrounded with elevated flaps. The caudal appendix was lost after larvae molted to the L3 stage, and in its place, 3 terminal papillae developed. Sense organs, such as 2 opposing phasmids and 8 papillae that were arranged into 2 circles, developed in the cephalic region of the L3 larva. The evidence of pathological consequences due to the presence of the L3 larva in the fly host are illustrated and discussed.

Latent inhibition, but not prepulse inhibition, is reduced during withdrawal from an escalating dosage schedule of amphetamine

The enhanced locomotor and stereotypic responses of the rat to repeated amphetamine (AMPH) administration are considered to be an animal model of positive schizophrenic symptoms. In contrast, behaviors observed during withdrawal from repeated AMPH are believed to model depression or anxiety. In the present study, the authors tested whether AMPH withdrawal might also elicit behaviors consistent with animal models of schizophrenia, specifically, disruptions in latent inhibition (LI) of 2-way active avoidance and prepulse inhibition (PPI) of startle. Rats treated with escalating doses of AMPH (6 days, 1-5 mg/kg ip) or saline were tested for LI and PPI during withdrawal. LI was eliminated by prior AMPH treatment in rats tested at 4, 13, and 28 days of withdrawal. In contrast, PPI did not differ between AMPH and control groups. These results support an interrelationship between repeated-AMPH and LI-disruption, but not PPI-disruption, models of schizophrenia.

Interactions between environmental stimulation and antipsychotic drug effects on forebrain c-fos activation

The immediate-early gene product Fos is differentially induced in the rat brain by the antipsychotic drugs haloperidol and clozapine. It is often claimed that although both drugs induce Fos in the nucleus accumbens, haloperidol but not clozapine increases Fos-like immunoreactivity in the striatum, whereas clozapine but not haloperidol increases Fos-like immunoreactivity in prefrontal cortex. Investigations of antipsychotic drug effects on Fos have typically administered high doses with pronounced sedative effects to behaviorally naive animals. In the present study, we compared the effects of low doses of haloperidol (0.1 mg/kg) and clozapine (5 mg/kg) on Fos-like immunoreactivity in rats which were either behaviorally naive, exposed to a novel environment or tested for two-way active avoidance. We determined that haloperidol increased Fos in the striatum and nucleus accumbens regardless of testing condition whereas clozapine markedly reduced the induction of Fos by behavioral testing in these regions; moreover, haloperidol dramatically increased prefrontal cortical Fos expression in animals placed in a novel environment, but not in testing-naive controls. From these results we suggest that antipsychotic drug-induced patterns of Fos expression in the rat are highly dependent on animals' concurrent behavioral status, perhaps reflecting neuroanatomically specific interactions between antipsychotic drugs and environmental stressors which also may occur in the schizophrenic condition.

Effects of psychostimulant withdrawal on latent inhibition of conditioned active avoidance and prepulse inhibition of the acoustic startle response

RATIONALE

Chronic intermittent administration of amphetamine and cocaine can precipitate psychotic episodes in humans and produce persistent behavioral changes (i.e. increased locomotion, stereotypy) in the rat. The psychostimulant sensitization model of psychosis holds that the repeated administration of drugs such as amphetamine and cocaine induces long-lasting neuroadaptations and behavioral outcomes in animals that parallel aspects of the schizophrenic condition.

OBJECTIVES

In the present study, we attempted to validate this model further by examining the effects of short-term withdrawal from repeated administration of cocaine and amphetamine on performance in two animal behavioral models of cognitive deficits found in schizophrenia: latent inhibition and prepulse inhibition. Reductions in both of these behavioral phenomena have been reported in schizophrenic patients and in acutely amphetamine-treated rats.

METHODS

Animals were tested after 4 days of withdrawal from 5 days of daily systemic 20 mg/kg cocaine or 1.5 mg/kg amphetamine injections for either latent inhibition of two-way active avoidance acquisition or prepulse inhibition of an acoustic startle response.

RESULTS

Our results indicate that, rather than reducing the expression of these behaviors, withdrawal from either cocaine or amphetamine enhanced the expression of latent inhibition of the active avoidance response while having no effect on prepulse inhibition of acoustic startle.

CONCLUSIONS

These data indicate that although the sensitized response to amphetamine and cocaine administration may model some aspects of schizophrenic psychosis, behaviors exhibited by sensitized animals in the absence of an acute drug challenge are not consistent with models of the positive symptoms of schizophrenia.

Putative steroidal pheromones in the round goby, Neogobius melanostomus: olfactory and behavioral responses

To identify potential hormonal pheromones of the round goby (Neogobius melanostomus), a species recently introduced to the Great Lakes, we used electro-olfactogram (EOG) recording to examine olfactory responsiveness to more than 100 steroids and prostaglandins. Neogobius detected free and conjugated 18-, 19- and 21-carbon steroids, but did not detect prostaglandins. EOG cross-adaptation, used to determine if Neogobius can discriminate the detected compounds at the sensory level, suggested that the detected steroids act on four classes of olfactory receptor mechanisms named (according to the most potent ligand for each): estrone, 17 beta-estradiol-3 beta-glucuronide, etiocholanolone, and dehydroepiandrosterone-3-sulfate. Although none of the detected steroids induced reproductive behaviors, exposure to steroids from three of the four receptor classes (estrone, 17 beta-estradiol-3 beta-glucuronide, or etiocholanolone) increased ventilation rate in males, whereas only etiocholanolone increased ventilation rate in females. Using the ventilation increase as a behavioral bioassay of steroid detection, behavioral cross-adaptation studies in males demonstrated that steroids discriminated at the sensory level are also discriminated behaviorally. These findings suggest the round goby may use steroids as putative pheromones.

Acute withdrawal from repeated cocaine treatment enhances latent inhibition of a conditioned fear response

Psychostimulant-induced locomotor sensitization and disrupted latent inhibition (LI) of a classically conditioned association are two paradigms that have been widely studied as animal behavioural models of psychosis. In this study we assessed the effects of withdrawal from the repeated intermittent administration of cocaine on LI of a conditioned fear response. Animals which were either preexposed (PE) to a tone conditioned stimulus (CS) or naive to the tone (i.e. non-preexposed: NPE) subsequently experienced 10 pairings of the tone CS with footshock. Afterwards, both groups received five daily injections of cocaine (20 mg/kg, i.p.) or saline. After 3 days of withdrawal from drug treatment, animals were tested for conditioned freezing to the context of the footshock chamber, and 1 day later, for conditioned freezing to the tone CS. Cocaine-sensitized animals exhibited markedly enhanced LI compared to saline-treated animals, due to the fact that NPE-cocaine animals spent more time freezing during the tone CS than NPE-saline animals, whereas PE-cocaine animals showed a tendency toward reduced freezing compared to the saline groups. While these results suggest the presence of increased anxiety in cocaine-withdrawn NPE animals, the absence of this effect in cocaine-withdrawn PE rats indicates that cocaine withdrawal also influences the retrieval of previously learned information.

Down-regulation of the macrophage lineage through interaction with OX2 (CD200)

OX2 (CD200) is a broadly expressed membrane glycoprotein, shown here to be important for regulation of the macrophage lineage. In mice lacking CD200, macrophage lineage cells, including brain microglia, exhibited an activated phenotype and were more numerous. Upon facial nerve transection, damaged CD200-deficient neurons elicited an accelerated microglial response. Lack of CD200 resulted in a more rapid onset of experimental autoimmune encephalomyelitis (EAE). Outside the brain, disruption of CD200-CD200 receptor interaction precipitated susceptibility to collagen-induced arthritis (CIA) in mice normally resistant to this disease. Thus, in diverse tissues OX2 delivers an inhibitory signal for the macrophage lineage.

Protistan parasite QPX of hard-shell clam Mercenaria mercenaria is a member of Labyrinthulomycota

Biomass of the protistan parasite QPX (quahaug parasite X) of hard-shell clam Mercenaria mercenaria was enriched from in vitro culture. The nuclear gene encoding the 18S RNA of the small-subunit ribosomal (ssu-rDNA) was recovered using the polymerase chain reaction (PCR) and sequenced. Phylogenetic analysis clearly showed that QPX is a member of phylum Labyrinthulomycota, within which it appears as a specific relative of Thraustochytrium pachydermum. These results confirm the provisional assignment of QPX to the Labyrinthulomycota made previously on the basis of morphological and ultrastructural characters found in some, but not all, geographic isolates.

Differential involvement of dopamine in the shell and core of the nucleus accumbens in the expression of latent inhibition to an aversively conditioned stimulus

Latent inhibition, the process whereby pre-exposure to a conditioned stimulus without consequence impairs subsequent learning of an association between the conditioned stimulus and an unconditioned stimulus, is reportedly disrupted in both amphetamine-treated rats and in acute schizophrenics. This has led to the suggestion that disruptions in latent inhibition model some of the cognitive impairments associated with hyperactive dopamine transmission as it is expressed in schizophrenic patients. Specifically, fluctuations in dopamine neurotransmission within the nucleus accumbens have been implicated in the mediation of latent inhibition; however, it has not been established whether these dopamine-mediated effects occur in the shell or core subregion of the nucleus. In the present study, 48h after conditioned stimulus-pre-exposed and non-pre-exposed animals experienced 10 pairings of tone and footshock, we measured extracellular levels of dopamine in the shell and core during the expression of latent inhibition to an aversively conditioned tone using in vivo microdialysis. Our results show that pre-exposure to the tone eliminated the conditioned release of dopamine in the shell of the nucleus accumbens and resulted in an attenuated conditioned freezing response to the tone conditioned stimulus. In contrast, dopamine release in the core was not affected by pre-exposure to the tone. These data suggest that it is specifically the shell of the nucleus accumbens in which alterations of dopaminergic tone, whether pharmacologically induced in rodents or the result of disease in humans, may act to disrupt latent inhibition.

Using Microwave Irradiation to Improve Preservation of Female Nematodes and Gall Tissues for TEM Observations

Microwave irradiation of glutaraldehyde-immersed samples was evaluated for the chemical fixation of 3-week-old galls that resulted from the infection of tomato roots (Lycopersicon esculentum) by a root-knot nematode, Meloidogyne incognita. Observation by transmission electron microscopy indicated that the best results were obtained when vials containing the intact galls were immersed in buffered glutaraldehyde and irradiated for 10 seconds then allowed to cool for 30 seconds; this procedure was repeated two additional times. Galls that were fixed by this method and subsequently embedded in resin provided thin sections that remained stable in the electron beam so that fine structural details could be evaluated and photographed. Root cortical cells displayed no indication of osmotic stress, which usually results in plasmolysis or displacement of the cytoplasm toward the interior of the cell. All organelles in the giant cells appeared normal and well fixed. Cross sections near the center of the gall showed that the hypodermis of the female was not separated from the cuticle, which in turn was appressed to the outer cell walls of the giant cells. No obvious evidence of shrinkage, distortion, or failure of resin infiltration into the female nematode was apparent. High magnifications of the female nematode indicated that fine structural features of the tissues were also well preserved. Immersion fixation combined with microwave irradiation not only improved fixation of older tissues but enabled preservation of stages and feeding sites that could not be easily obtained by conventional methods.

Effect of an ice-nucleating activity agent on subzero survival of nematode juveniles

Juveniles of five species of nematodes, Caenorhabditis elegans, Panagrellus redivivus, Pratylenchus agilis, Pristionchus pacificus, and Distolabrellus veechi, were added to solutions with (treatment) and without (control) a commercial ice-nucleating activity (INA) agent. Ten-microliter droplets of the solutions containing the juveniles were placed on glass microscope slides and transferred to a temperaturecontrolled freeze plate where the temperature was reduced to -6 to -8 degrees C. At this temperature, the droplets containing the INA agent froze while those without the agent remained liquid. After 2 minutes, the temperature of the plate was raised to 24 degrees C, and the slides were examined with a light microscope to determine the viability of the juveniles. The results showed that usually most juveniles (43% to 88%, depending on species) in solutions that did not contain the INA agent (controls) were active, indicating that the juveniles were capable of supercooling and were thereby protected from the subzero temperatures. Alternatively, less than 10% of the juveniles that had frozen for 2 minutes in solutions containing the INA agent remained viable, indicating that inoculative freezing of the solution was lethal to the supercooled juveniles. Our results suggest that, in geographical areas where winter temperatures may not be sufficiently low or sustained to freeze soil, the addition of an INA agent may help induce ice nucleation and thereby reduce the populations of nematode species that are unable to survive when the soil solution is frozen.

Low-dose clozapine pretreatment partially prevents haloperidol-induced deficits in conditioned active avoidance

The effectiveness of neuroleptics in disrupting conditioned active avoidance has led to the widespread use of this test as an index of antipsychotic efficacy, whereas the tendency for these drugs to induce catalepsy is believed to reflect their propensity to cause extrapyramidal motor side-effects. Although the typical neuroleptic haloperidol produces catalepsy as well as profound deficits in conditioned active avoidance, the atypical neuroleptic clozapine does not induce catalepsy and is less effective than haloperidol in disrupting active avoidance. Furthermore, clozapine pretreatment prevents haloperidol-induced catalepsy. We investigated whether clozapine pretreatment might also reduce the disruptive effects of haloperidol on two-way active avoidance. We assessed the avoidance acquisition of the following drug treatment groups in which all animals received two injections prior to testing: vehicle + vehicle, vehicle + haloperidol (0.1 mg/kg, i.p.), clozapine (2.5, 5.0 or 10 mg/kg, i.p.) + haloperidol (0.1 mg/kg, i.p.), or clozapine (2.5, 5.0 or 10 mg/kg, i.p.) + vehicle. Haloperidol-pretreated animals showed markedly impaired active avoidance, deficits which were improved by 2.5 and 5 mg/kg but not by 10 mg/kg clozapine pretreatment. These data suggest that the disruptive effects of haloperidol on conditioned active avoidance partially mirror its capacity to induce catalepsy and extrapyramidal motor symptoms. Furthermore, this study indicates that clozapine may be effective in reducing motor side-effects caused by typical neuroleptics.

Ichthyophonus irregularis sp. nov. from the yellowtail flounder Limanda ferruginea from the Nova Scotia shelf

A previously described unusual form of the protistan parasite Ichthyophonus, differing in morphological and developmental features from I. hoferi sensu Plehn & Mulsow, was recovered from yellowtail flounder Limanda ferruginea Storer from the Brown's Bank area of the Nova Scotia shelf. The nuclear gene encoding the rRNA of the small ribosomal subunit was amplified from this unusual form of Ichthyophonus using the polymerase chain reaction, sequenced and aligned with other eukaryote small subunit (ssu)-rDNAs. Inferred phylogenetic trees clearly show that its ssu-rDNA is distinct from those of 2 isolates of I. hoferi sensu Plehn & Mulsow from different hosts and geographical locations (herring in the North Sea, and yellowtail flounder from the Nova Scotia shelf). We consider the unusual form to be a separate species, I. irregularis. The occurrence of a second, distinct type of Ichthyophonus within a single host species raises the possibility that ichthyophoniasis could be produced by different (although related) pathogens, and in some cases, by concurrent infections of the two.

Structural organization of the sex pheromone gland in Helicoverpa zea in relation to pheromone production and release

Morphological location of the sex pheromone producing area in the ovipositor of the female corn earworm Helicoverpa zea, was correlated with gas chromatographic analysis of the extracted pheromone. Histological studies showed that the pheromone gland occupied an almost complete ring of specialized columnar cells between the 8th and 9th abdominal segments. Ultrastructure of the pheromone gland cells revealed distinct features such as microvilli, pockets of granular material, intercellular canals with abundant desmosomes. Apparent changes in some of these features are associated with phases of pheromone production and non-production. Examination of the tissue with low temperature scanning electron microscopy showed the presence of excreted droplets at the tips of cuticular hairs in the glandular area during the period of pheromone production.

Prenatal cocaine produces signs of neurodegeneration in the lateral habenula

The lateral habenula is a nucleus in the dorsal thalamus that innervates midbrain dopaminergic and serotonergic nuclei via projections through its major efferent pathway, the fasciculus retroflexus (FR). It was previously demonstrated that cocaine administered continuously to adult rats over several days produces neurodegeneration in the lateral habenula and FR. Because exposure to cocaine during pregnancy reportedly can cause neurobehavioral deficits, we examined whether rat fetuses exposed to continuous cocaine during the last week of gestation would similarly demonstrate selective neurodegeneration in the lateral habenula. On day 17 of gestation, dams were implanted with two silicone pellets, each containing either vehicle or one of 2 doses of cocaine (80 mg or 55 mg per pellet). Degenerating neurons containing silver deposits were counted in lateral habenula and in the striatum. Cocaine-exposed pups had significantly more silver-stained cells in the lateral habenula than vehicle-treated pups, but similar numbers of silver-stained cells were present in the striatum of all three groups. When similarly treated vehicle- and cocaine-exposed animals were tested behaviorally at 60 days of age, they did not differ on measures of open field activity, open arm avoidance on the elevated plus-maze or conditioned place preference for cocaine, although a linear trend analysis indicated some hyperactivity of the cocaine-pretreated pups during the place preference test. These results indicate that continuous cocaine exposure has selective neurotoxic effects on the habenula of the developing fetus similar to cocaine's effects in the adult.

Preparation and pharmacokinetics of samarium(III)-153-labeled DTPA-bis-biotin. Characterization and theoretical studies of the samarium(III)-152 conjugate

The complex(153)Sm(III)DTPA-bis-biotin was prepared with a 99% radiochemical purity and a specific activity of 370 MBq/mg employing a molar ratio of DTPA-bis-biotin/Sm from 2 to 4 at pH 8.0. In vitro studies demonstrated that the complex is stable after dilution in saline and in human serum. Avidity of labeled biotin for avidin was not affected by the labeling procedure. Pharmacokinetic data of (153)Sm(III)DTPA-bis-biotin in normal mice showed that blood clearance is biexponential during the time interval from 0 to 24 h and that 3 h postinjection 92 +/- 4.32% of the dose is eliminated in the urine. To have further evidence which could sustain that (153)Sm(III)DTPA-bis-biotin is stable in solution as a real coordination complex, (152)Sm(III)DTPA-bis-biotin was obtained in macroscopic quantities and its characterization was done by IR, TGA, and conductivity measurements. The results indicated that the complex was chemically pure, where the Sm(3+) ion is neutralized by three carboxylate groups of the DTPA-bis-biotin ligand and coordinated to it. Using the Force Field method followed by ab initio calculations, the DTPA-bis-biotin and the Sm(III)DTPA-bis-biotin molecules were done. Accordingly, the coordination sphere of Sm(III) was totally satisfied with nitrogen and oxygen donors; the best coordination number was 9. The conformation geometry of both compounds is presented.

The prognosis of small primary breast cancers

The Nottingham Prognostic Index (NPI) is an integrated prognostic index used to predict patient survival for women with invasive breast cancer. The index is based on invasive tumour size, histological lymph node stage and tumour grade. The value of such an index has been questioned in small invasive breast cancers and it has been suggested that size is the only necessary prognostic determinant. The aims of this study were to determine the extent of regional lymph node involvement and survival in women with small invasive breast cancers and to assess the value of the NPI. Between 1976 and 1994, 2684 women aged < or = 70 years were treated for primary operable invasive breast cancers of < or = 5 cm in maximum diameter, of which 318 measured < or = 1 cm. Follow-up data were evaluated to determine histological factors important in predicting survival outcomes in women with cancers < or = 1 cm in diameter and comparing their survival according to the NPI with all women treated for primary operable breast cancers < or = 5 cm in maximum diameter. Histological lymph node involvement was demonstrated in 56/318 (18%) of cancers of < or = 1 cm in diameter. Significant survival differences were demonstrated for small breast cancers according to lymph node stage, vascular invasion and histological tumour grade. Only lymph node stage and histological tumour grade were independent prognostic indicators using a multivariate Cox model. The survival curves for small tumours stratified by the NPI were similar to those of cancers up to 5 cm in diameter. The results indicate that lymph node staging and histological grading are still important prognostic determinants for breast cancers < or = 1 cm in diameter. An axillary node staging procedure should be performed for all invasive breast cancers < or = 1 cm in diameter. The NPI remains relevant for small breast cancers.

Genomic rearrangements in the flagellin genes of Proteus mirabilis

Molecular analyses have revealed that Proteus mirabilis possesses two genes, flaA and flaB, that are homologous to each other and to flagellin genes of many other species. Both swimmer and swarmer cells transcribe flaA, but not flaB. FlaA- mutants are non-motile and do not differentiate showing the essential role of flaA in swarmer cell differentiation and behaviour. At a low frequency, motile, differentiation-proficient revertants have been found in FlaA-populations. These revertants produce an antigenically and biochemically distinct flagellin protein. The revertant flagellin is the result of a genetic fusion between highly homologous regions of flaA and flaB that places the active flaA promoter and the 5' coding region of flaA adjacent to previously silent regions of flaB generating a hybrid flagellin protein. Analysis of the flaA-flaB region of two such revertants reveals that a portion of this locus has undergone a rearrangement and deletion event that is unique to each revertant. Using a polymerase chain reaction (PCR) to amplify the falA-flaB locus from wild-type swimmer cells, swarmer cells and cells obtained after urinary tract infection, we uncover at least six general classes of rearrangements between flaA and flaB. Each class of rearrangement occurs within one of nine domains of homology between flaA and flaB. Rearrangement of flaA and flaB results in a hybrid flagellin protein of nearly identical size and biochemical properties, suggesting a concerted mechanism may be involved in this process. The data also reveal that the frequency and distribution of flaAB rearrangements is predicted on environmental conditions. Thus, rearrangement between flaA and flaB may be a significant virulence component of P. mirabilis in urinary tract infections.

A computer controlled analysis of freezing behaviour

The conditioned freezing response in rats has been much used both by psychologists and neuroscientists to investigate the behavioural effects of brain lesions and of changes in motivational state. The primary advantage of the freezing response is that it can be used without motivational manipulations such as food or water deprivation. Previously, freezing has been measured by a human observer either from video recordings or during the test sessions themselves. But these methods of data collection have potential disadvantages. In the present paper, we describe a new, computer controlled, automated procedure for assessing conditioned freezing. Each conditioning chamber contains a mini-video camera. Behaviour is analysed on-line by means of a programme which compares every two adjacent seconds of video tape to generate a screen representing the percentage difference between them. A difference of <0.05% (50 pixels) is classified as a freezing response. Experiments are described in which we measure conditioned freezing and its development over time, in response to contextual cues and to a discrete tone which had been paired with foot shock. We demonstrate our apparatus and methods of data analysis to be sensitive to: number of tone-shock pairings, rat strain and tone pre-exposure.

Odorant-binding proteins of true bugs. Generic specificity, sexual dimorphism, and association with subsets of chemosensory sensilla

Odorant-binding proteins (OBPs) in insects occur within olfactory sensilla, and are thought to transport chemical stimuli to receptors on dendrites of sensory neurons. Until recently, knowledge of OBPs in insects was limited to moths and Drosophila. We discovered an antennal-specific protein (Lygus [lineolaris] antennal protein, LAP) with a unique N-terminal sequence in the true bug, Lygus lineolaris. We localized LAP to antennae, determined its molecular weight (16 kDa), and showed that while it was expressed in nymphal antennae, its levels dramatically increased in adults concurrent with increases in numbers of olfactory sensilla and electrical responses to odors. In our current study, we used immunological techniques to demonstrate in more detail that LAP occurs only in antennae, and to show its expression within Lygus species. LAP was expressed more in male antennae than in antennae of females for the Lygus species examined. Anti-LAP did not recognize antennal proteins of two other genera of bugs. Immunocytological studies showed LAP primarily within the sensillar lymph of type 1 and type 4 sensilla on antennae. These observations strongly suggest LAP to be an OBP, and our discovery and characterization of OBPs in true bugs provides a third order for use in the study of evolution of OBPs in insects.