Detection of Neisseria gonorrhoeae and Chlamydia trachomatis in pharyngeal and rectal specimens using the BD Probetec ET system, the Gen-Probe Aptima Combo 2 assay and culture.

OBJECTIVES: This study compared the sensitivity and specificity of culture and two nucleic acid amplification tests (NAATs): the BD Probetec ET system (PT) and the Aptima Combo 2 (AC2) in detecting Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) in pharyngeal and rectal specimens. METHODS: Male subjects were prospectively recruited at an MSM clinic in Toronto, Canada. Pharyngeal and rectal specimens were obtained for GC and CT culture, PT and AC2. Urine was also obtained for PT. A true positive was defined as: (1) positive culture, (2) positive PT and AC2 at the same site or (3) a single positive NAAT and detection of the same organism by any method at another site. RESULTS: 248 subjects were recruited. The prevalence of pharyngeal GC was 8.1%, rectal GC 11.7%, pharyngeal CT 2.0% and rectal CT 7.7%. The sensitivity of culture for pharyngeal GC and CT was 0%; 41.4% for rectal GC and 21.1% for rectal CT. The sensitivity of PT for pharyngeal GC, rectal GC, pharyngeal CT and rectal CT was 95.0%, 93.1%, 80.0% and 94.7%, respectively. The sensitivity of AC2 was 95.0% for pharyngeal GC and 100% at all other sites. Specificity was consistently above 98%. CONCLUSIONS: PT and AC2 detected GC and CT with superior sensitivity compared to culture. They detected 73 pharyngeal or rectal GC and CT infections compared to 16 by culture, using a rigorous gold standard. NAATs should be the method of choice for the detection of GC and CT in extragenital sites in men who have sex with men.

Anatomic and physiologic reference values in least shrews (Cryptotis parva).

BACKGROUND AND PURPOSE: The least shrew is an established animal model for reproductive and pharmacologic research. Biologic reference data are needed to assess animal health status and provide a rationale for use of novel statistical programs to evaluate the effects of orally administered substances in toxicologic and pharmacologic studies. METHODS: Organ weights, blood biochemical and hematologic values, and food and water consumption data were collected from 50-day-old shrews after two weeks' consumption of a standard feline diet. RESULTS: In general, data correlated well with values reported for other mammalian species. Plasma phosphorus concentration was high. There was a significant difference in food and water consumption per gram of body weight between shrews at lower and upper (+/- 1 SD) weight ranges for the study. The 3.2-g animals consumed 27% more food per gram of body weight than did the 5.0-g animals. CONCLUSIONS: The high phosphorus concentration was attributed to hemolysis resulting from the axillary cut method of blood sample collection. The small size of the shrew allowed demonstration of the Kleiber effect within a +/- 1 SD weight range in a single species. The phenomenon necessitates the use of statistical methods other than the typical tests establishing the significance of the differences between the means of groups for oral toxicologic and pharmacologic studies.

The head-twitch response in the least shrew (Cryptotis parva) is a 5-HT2- and not a 5-HT1C-mediated phenomenon.

Our initial studies suggested that the 5-HT2/1C agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl-2-aminopropane [(+/-)-DOI] produces both the head-twitch response (HTR) and the ear-scratch response (ESR) in mice via stimulation of 5-HT2 receptors. However, challenge studies revealed that these behaviors are produced via two different receptors (possibly 5-HT2 and 5-HT1C). Due to a lack of selective agents one cannot designate a particular response for the activation of a specific receptor. The purpose of the present study was to investigate such behaviors in the least shrew, which is more sensitive to (+/-)-DOI than rodents. IP injection of (+/-)-DOI in shrews produced a dose-dependent (bell-shaped) and time-dependent increase in the HTR frequency. The (+/-)-DOI-induced HTR was equipotently and completely attenuated by the 5-HT2/1C antagonists ketanserin and spiperone. The 5-HT1C antagonist with 5-HT2 agonist action, lisuride, also produced the HTR in a bell-shaped dose- and time-dependent fashion. Central injections of both (+/-)-DOI (0.2 microgram) and lisuride (0.5 microgram) also induced the behavior. Both peripheral and central administration of lisuride failed to produce the ESR. (+/-)-DOI significantly induced the ESR only at the highest dose tested (2.5 mg/kg, IP). Centrally administered (+/-)-DOI (0.2 microgram) produced more ESRs relative to vehicle controls; however, the difference did not attain significance. At low doses (0.31 and 0.63 mg/kg), (+/-)-DOI had no effect on locomotor activity, but it significantly attenuated the behavior at larger doses. Both low and high doses of lisuride increased the motor activity. Spiperone dose-dependently suppressed locomotion, whereas ketanserin had no effect. The present results suggest that the HTR is a 5-HT2 receptor-mediated event and changes in locomotor activity do not affect the induced HTR.

Termination of thalamic intralaminar nuclei afferents in visual cortex of squirrel monkey.

The projection of the thalamic intralaminar nuclei (ILN) upon the visual cortex in the squirrel monkey was studied using anterograde, autoradiographic techniques. In area 17, the ILN afferents terminate in the inner and outer portions of lamina V, whereas in areas 18 and 19 the fibers terminate more diffusely along the laminae V-VI boundary. Widespread labeling of layer I is seen throughout the occipital cortex.

Is there morphological separation between the spinal cord motor nuclei which innervate the heads of a multiheaded muscle?

Horseradish peroxidase was injected into the individual heads of the pectoralis muscles of the dog or applied to the nerve which supplies each of these heads. The location and numbers of labeled motoneurons in the spinal cord were studied using light microscopy. There was longitudinal overlap of the pectoral nuclei, but no separation in their mediolateral or dorsoventral positions. The cutaneous trunci muscle motor nucleus is distinctly separate from the motor nuclei of the pectoral muscles, even though they share a common nerve supply. The methods of horseradish peroxidase application to the cut nerve or injection into the muscle are compared.

Location of the cutaneous trunci motor nucleus in the dog.

Using the methods of muscle injection of horseradish peroxidase (HRP) and application of HRP to the proximal stump of the cut lateral thoracic nerve (LTN), the motor nucleus of the cutaneous trunci muscle (CTM) has been located predominantly in C8 and T1 spinal cord segments in the ventral and ventrolateral nuclei of Rexed's Lamina IX. Cells of the nucleus are somatotopically arranged rostro-caudally to correspond to the rostro-caudal segmentation. There was a higher average number of HRP-filled cells per section and greater rostro-caudal extent of the nucleus for the cut nerve technique than for the muscle injection technique. Evidence is presented that the CTM is an appendicular muscle in spite of its obvious axial position on the trunk.

Projections of the dorsal lateral geniculate and lateral posterior nuclei to visual cortex in the rabbit.

The origin and terminations of thalamic inputs to the striate cortex and the occipital cortex of the rabbit were studied using both anterograde autoradiographic techniques and retrograde transport of horseradish peroxidase (HRP). After injections of [3H]-leucine into the dorsal lateral geniculate nucleus (DLGN) the transport of radiolabeled material was demonstrated in separate loci in both the striate and the occipital cortex. In both these cortical areas, the principal site of geniculocortical termination was in lamina IV with some diminished input spreading into laminae II-III and a light termination in layer I overlying the lamina IV termination. Layer VI of striate cortex received a substantial projection from DLGN while infragranular laminae of occipital cortex received a similar although lighter and more diffuse projection. The lateral posterior nucleus (LPN) was similarly demonstrated to project to both striate and occipital cortices, the projection terminating principally in lamina IV of occipital cortex, lamina V of striate cortex, and layer I over a large, continuous area of the posterior pole of the cortex. Moreover, a projection from LPN to the retrosplenial cortex medial to the striate area was consistently seen. The autoradiographic demonstration of a projection from DLGN and LPN to both striate cortex and occipital cortex was corroborated by the retrograde studies. Following the injection of HRP into either the striate or occipital cortex, columns of retrogradely filled somata were identified in both the DLGN and LPN. The location of the column of labeled neurons within each nucleus varied predictably with the location of the injection in either the striate or the occipital cortex.

Studies on the mechanism of the epileptiform activity induced by U18666A. II. Concentration, half-life and distribution of radiolabeled U18666A in the brain.

The concentration, half-life, and distribution in brain of U18666A, a drug that can drastically alter cerebral lipids and induce a chronic epileptiform state, was determined following both acute and chronic drug administration. U18666A specifically labeled with tritium was prepared by custom synthesis. Brain levels of 1 x 10(-6)M and higher were reached soon after giving an acute 10-mg/kg dose (i.p. or s.c.) of U18666A containing 7-3H-U18666A of known specific activity. A steady state concentration of 1 to 2 x 10(-6)M was reached with chronic injection of 10 mg/kg every 4th day, a treatment schedule that results in altered brain lipids and induction of epilepsy if begun soon after birth. The disappearance of U18666A from both brain and serum was described by two similar biexponential processes, a brief rapid clearance (t1/2 = 10 h) and a sustained and much slower one (t1/2 = 65 h). Brain levels of the drug were about 10 times higher than serum at all times examined. Few differences were seen in the regional distribution of radiolabeled drug in brain as determined by both direct analysis and by autoradiographic examination; but the drug did concentrate in lipid-rich subcellular fractions. For example, the synaptosome and myelin fractions each contained about 25-35% of both the total 3H-labeled drug and total lipid in whole brain. The lipid composition of these fractions was drastically altered in treated animals. In conclusion, the chronic epileptiform state induced by U18666A does not appear to involve localization of the drug in a specific brain region or particular cell type. Rather, the condition could involve localization of the drug in lipid-rich membranes and marked changes in the composition of these membranes.

A review of axon collateralization in the mammalian visual system.

Axon collateralization appears to represent a prominent feature of the mammalian visual system. Both anatomical and electrophysiological evidence reveal that axon branching occurs in the retinofugal, geniculocortical and visual corticifugal projections. Most of this evidence is provided by studies on the cat, but enough data are available from investigations on the rat and monkey to permit certain interspecies differences to be recognized and evaluated. Axon branching allows individual axons to provide innervation to two or more targets and generally to transmit the same type of visual information to these targets. There is abundant evidence to suggest that two of the three functional classes of retinal ganglion cells and geniculate relay cells (namely Y and W ganglion and relay cells) utilize axon branching; however, few details regarding this subject are currently available. The third functional class of ganglion and relay cells (X ganglion and relay cells) essentially lacks axon branches. This review has three primary goals: (1) to review the pertinent anatomical and electrophysiological literature dealing with axon branching and to discuss areas in which information is meager and further investigation necessary; (2) to emphasize the need for applying recently developed techniques, such as double-labeling of neurons and electrical collision, to the study of axon collateralization, and (3) to formulate some hypotheses concerning the functional significance of axon branching.

An autoradiographic study of the projections of visual cortical area 1 to the thalamus, pretectum and superior colliculus of the rabbit.

The projections of visual cortical area 1 (vl) to the thalamus, pretectum and superior colliculus of the rabbit have been studied by Giolli and Guthrie ('67, '71) using the Nauta and Fink-Heimer methods to determine the course and distribution of degenerating nerve fibers. The present study represents a reinvestigation of these same projections utilizing the tracing method of autoradiography. An injection of 3H leucine was produced within a small region of vl in each of 18 adult albino rabbits, and the brains were subsequently processed for autoradiography by the method of Cowan et al. ('72). The results have confirmed the observations of Giolli and Guthrie ('67, '71) (1) by showing that vl of the rabbit projects to the thalamic reticular nucleus, the ventral lateral geniculate nucleus, the dorsal lateral geniculate nucleus; the pulvinar, the anterior and posterior pretectal nuclei and the superior colliculus and (2) by showing that a particular retinotopic organization is present in each of these projections. However, unlike Giolli and Guthrie ('67, '71), the present autoradiographic study has further revealed (1) that both the ventrolateral and the posterior thalamic nuclei receive inputs from vl and (2) that the nucleus of the optic tract is not innervated by axons originating from vl.

Corticocortical fiber connections of the rabbit visual cortex: a fiber degeneration study.

Corticocortical fiber projections of the striate and occipital cortex of the rabbit, as degined by Rose ("31), have been determined by fiber degeneration methods following the production of cortical lesions within each of 24 rabbits. We have assumed that the striate and occipital cortices correspond respectively to the visual cortical areas 1 and 2 (VI and V2) which have been demarcated electrophysiologically by Thompson et al. ("50). A study of the ipsilateral fiber projections of the striate and occipital cortex of the rabbit reveals three distinct sets of associational corticocortical connections. (1) Neurons located in layers I-III of all regions of the striate cortex and the occipital cortex send fibers to terminate prodominantly in layer V, but also in layers IV and VI, immediately beneath the cells of origin; however, the cells in the supragranular layers have not been found to send fibers to any other region of cerebral cortex. (2) The binocular portions of VI and V2 appear to be interconnected ipsilaterally since cells in layers IV-VI of the lateral striate cortex have been shown to project to all layers of a restricted, adjacent portion of the medial occipital cortex; and the cells in layers IV-VI of medial occipital cortex send a similar, restricted projection to the adjacent lateral striate cortex. (3) Nerve cells in layers IV-VI of the lateral striate cortex (binocular VI) send a restricted projection to the lateral portion of the occipital cortex. (4) After all lesions of the striate and/or occipital cortices, degenerating fibers are seen radiating away from the lesion in layer I; the origin of these degenerating fibers could not be determined. The following observations have been made concerning the origins and terminations of commissural corticortical fibers. (1) after ablation of most of the visual cortex of one side, commissural fibers are seen to terminate in all cortical layers in two narrow bands of visual cortex: one band occupies both sides of the striate-occipital boundary; the second band is found in the lateral portion of occipital cortex. (2) More punctate lesions reveal that commissural fibers arise from layers IV-VI of the lateral striate cortex and medial occipital cortex (binocular portions of V1 and V2 respectively) and end in homotopic areas of the contralateral cortex.