The locust wing hinge stretch receptors. I. Primary sensory neurones with enormous central arborizations.

In locusts a single-celled stretch receptor (SR) neurone at the base of each wing monitors wing elevation and contributes to the control of the flight motor output. The central projections of these neurones are very complex but consistent in detail in the three species studied (Chortoicetes, Locusta and Schistocerca). The hindwing SR projects to the second and third thoracic ganglia, the forewing SR to the first, second and third thoracic ganglia. Both send fine axons into the abdominal connective. Within the ganglia each SR forms an extensive arborization, entirely ipsilateral and mainly in the dorsal neuropile, divided into medial, mediolateral, and lateral branches. The projections of the two ipsilateral SR neurones overlap almost completely in the second and third ganglia. There are recurrent loops between branches of a single neurone both within and between ganglia. Light microscope analysis shows apparent contacts between the SR aneurones and flight motor neurones and other wing sensory afferents, as well as long interneurones, other motor neurones and two types of multiaxonal neurones of unknown function. There are three groups of contacts between each SR and a flight motor neurone: laterally on the main branches, medially with the terminal twigs; and in the anterior dorso-medial glomerulus, where the inter ganglionic recurrent branch also terminates. All contacts are ipsilateral except for those with the contralateral branches of the dorsal longitudinal muscle motor neurones. We suggest that the SR neurones are multifunctional. Differential information transfer could result both from the spatial distribution of synaptic connections with the motor neurones and from filtering caused by low safety factors at branch junctions. Information in the lateral branching could be used for general excitation and control of firing frequency of the motor neurones; that in the medial branch for wing control and co-ordination.

The locust wing hinge stretch receptors. II. Variation, alternative pathways and "mistakes" in the central arborizations.

The central arborizations of the stretch receptor (SR) neurones are very consistent from one individual to another. Superimposition of normalized neurones from eight individuals of Locusta show very little variation even in the detailed branching pattern. There is, however, a commonly found alternative course for the main medial branch in the metathoracic ganglion. Rare, radical departures from the normal branching pattern are termed "mistakes." Only three have been found, all in the forewing SR projection, one with an extra branch and two with missing branches. Terminals of twigs in the alternative region of the medial branch occupy consistent positions in the neuropile, although these are reached by different routes. Mistakes have terminals in areas normally containing SR endings. Both these findings suggest that there may be labelled sites in the neuropile which the growing tips of the SR neurones seek out.

A cobalt study of medullary sensory projections from lateral line nerves, associated cutaneous nerves, and the VIIIth nerve in adult Xenopus.

The medullary projections of the anterior lateral line nerve, dorsal branch (Alln.d), the posterior lateral line nerve, dorsal branch (PLLn.d), associated cutaneous nerves, and the VIIIth nerve in Xenopus laevis have been delineated by axonal infusion of cobalt chloride and silver intensification. The peripheral innervation of the posterior lateral line sense organs has also been traced. From wholemount and sectioned preparations, we describe three central projections, extending the length of the ipsilateral medulla but occupying distinct zones: lateral line afferents dorsomedially, stato-acoustic dorsolaterally, and cutaneous ventrolaterally. Arborizations of ALLn.d and PLLn.d afferents are morphologically similar, intermingling throughout the lateral line lobe. Each divides into ascending and descending limbs bearing collaterals, which terminate in the lateral line neuropile and nucleus. Evidence is presented for directional and positional mapping in the branching of individual PLLn.d afferents and for topography in the ALLn.d projection. Second-order neurones have been identified by transneuronal staining and their axons traced into the contralateral torus semicircularis. The morphology of efferent neurones is also described. Rostral branches of PLLn.d also contain cutaneous afferents which run through the medulla into the spinal cord, similar to the nerve V (cutaneous) projection. In nerve VIII preparations, the projection to the compact cochlear nucleus and the massive vestibular projection are identified. Cutaneous and vestibular but not lateral line afferents extend into the cerebellum. The separation of VIIIth nerve and lateral line afferents in Xenopus medulla is considered as evidence against the validity of the acousticolateralis concept. Information processing in the lateral line lobe is discussed in relation to connectivity patterns between first- and second-order neurones.

Identifiable neurons in the locust central nervous system that react with antibodies to serotonin.

A detailed account is given of a number of neurons in the locust central nervous system that react with antibody raised to serotonin-albumin complex. The antibody was applied to a series of frozen sections of locust ganglia and visualized by using the peroxidase immunohistochemical procedure. The neurons described include certain afferents and their related neuropiles, a small number of efferents and several systems of interneurons, some of which are segmentally repeated, some run from the brain through the whole nerve cord, while others are confined to the brain. It has been possible to identify many of the neurons from previous descriptions obtained from cobalt, Golgi, and osmium ethyl gallate methods.

Synaptic connections between the hindwing stretch receptor and flight motor neurones in the locust revealed by double cobalt labelling for electron microscopy.

Synaptic interactions between sensory and motor neurones in the locust flight system have been investigated by using intracellular labelling with cobalt and nickel for electron microscopy. Simultaneous axonal filling of two neurones with different concentrations of metal ions produces differential labelling, so that contacts between them in the central nervous system can be recognized. We have investigated the connectivity of the hindwing stretch receptor neurone (SR) with a direct hindwing depressor motor neurone (MN 127) known from physiological experiments to receive monosynaptic input from the SR, and an indirect hindwing depressor motor neurone (MN 112/1), for which no monosynaptic connection with the SR has been reported. We have found no direct synapses between the SR and MN 112/1, although some of their branches lie close together in the neuropile. We have, however, found some evidence for polysynaptic connections between them. There are many synapses of conventional dyadic morphology from both the lateral and mediolateral branches of the SR to MN 127; the medial branch was not examined. Those from the lateral branch contact the motor neurone on branches close to the neuropilar segment, while those from the mediolateral branch contact long, thin distal twigs. We estimate that there are about 600 anatomical synapses between these two neurones. Our results suggest that a large number of widely distributed anatomical synapses constitute the physiological synaptic connection between the SR and MN 127. The dyadic arrangement of these synapses provides an anatomical correlate for the physiologically established divergence of SR outputs onto interneurones and motor neurones.

A comparative study of neck muscle motor neurons in a cricket and a locust.

The gross morphology of the neck muscles of a cricket (Gryllus campestris) and their innervation are described and compared with a locust (Schistocerca gregaria). The motor neurons innervating the neck muscles were stained in crickets and locusts with cobalt chloride introduced via the nerve endings in the muscle. The two species show overall similarities, not only in position of the neck motor neurons in suboesophageal, prothoracic, and mesothoracic ganglia but also in motor neuron morphology. However, muscle 60 in the cricket is innervated by a unique motor neuron with its axon in prothoracic nerve 3, instead of sharing motor neurons in suboesophageal nerve 8 and mesothoracic nerve 1 with muscle 59, as in locust. Muscle 62 has the same attachments and innervation with similar motor neurons in cricket and locust but a different mechanical function in the two species. The findings are discussed with respect to possible segmental homologies and to the origins of the muscles as either dorso-ventral or longitudinal. As several muscles share the same motor neurons, we suggest that neck muscle function be described in terms of "behavioural units of action."

Some insect sensory neurones contain 5-hydroxytryptamine.

Immunocytochemistry of the locust central nervous system shows that most segmental nerves, in particular those of the legs, contain afferent fibres that react with antibody to 5-hydroxytryptamine (5-HT). Adsorption controls indicate that the antigen is 5-HT or a closely related compound. This is supported by the finding of significant amounts of 5-HT in leg nerves using reverse phase high-performance liquid chromatography (HPLC) and electrochemical detection. On the other hand 5-HT was not detectable in locust antennal and cercal nerves with either immunocytochemistry or with HPLC. These results strongly support that some populations of sensory neurones in the locust contain 5-HT.

Socioeconomic status and attitudes of 51 patients with giant basal and squamous cell carcinoma and paired controls.

BACKGROUND: Giant nonmelanoma skin cancers are disfiguring and clearly visible. This prospective study examined tumor characteristics, ie, location, tumor type, duration, and the socioeconomic status and attitudinal characteristics of these patients and their interactions with the medical community. DESIGN: From 1979 through 1993, preoperative questionnaires about age, sex, tumor duration, prior treatment, socioeconomic status, and attitudinal concerns were completed by 51 patients with giant tumors and randomly matched controls. Additional data completed by the physician included tumor type, location, and preoperative clinically apparent diameter of the tumor. RESULTS: Giant tumors were more frequent on the scalp in men. Lower socioeconomic status and infrequent physician visits were characteristic of those with giant lesions. Those with giant lesions were less concerned about their general health, had a greater sense of shame about their appearance, had greater belief that since prior treatment did not help the problem then nothing else would, and had an increased frequency of perceived prior reassurance. Women and those younger than 65 years of both sexes were more concerned about economic costs and/or the time lost from work or caring for others. CONCLUSIONS: Health promotion by early detection and treatment of these nonmelanoma skin cancers in elderly men could prevent extensive surgical efforts later in the course of the disease. Skin screening examinations by all physicians and better public awareness of the signs of skin cancer, especially among elderly men, would enhance early detection; however, it is not clear that early detection by physicians enables treatment. Strategies to assist individuals in overcoming their barriers to accessing care need to be provided.

Changing etiology of vocal fold immobility.

HYPOTHESIS: Vocal fold immobility is a sign of underlying disease. When the etiology remains unclear, evaluation may become time consuming and costly, and directed work-up imperative. This study examined the hypothesis that the etiologies of vocal fold immobility are changing, with extralaryngeal malignancies and nonthyroidectomy surgical trauma having become more common causes. METHODS: A retrospective review of consecutive patients with vocal fold immobility who had an adequate workup to determine the etiology. RESULTS: Three hundred ninety-seven cases with a determined etiology were identified, yielding 280 unilateral and 117 bilateral immobilities. The largest single category in unilateral immobility was nonlaryngeal malignancy--69 patients (24.7%)--80% of which were pulmonary or mediastinal, followed by 67 patients (23.9%) with immobility secondary to surgical trauma. Thyroidectomy accounted for only 8.2%. The leading cause of bilateral immobility was surgical trauma-30 patients (25.7%)--21 (18%) of whom had thyroidectomy. Acute and chronic intubation injuries accounted for 21 unilateral (7.5%) and 18 bilateral (15.4%) cases. CONCLUSIONS: These data indicate a changing etiology of vocal fold immobility, with growing percentages of extralaryngeal malignancies and surgery-related injuries. These findings have implications for the timing and method of management based on anticipated outcome.

Determination of the efficacy of topical oral pilocarpine for postirradiation xerostomia in patients with head and neck carcinoma.

Pilocarpine hydrochloride suspended in a candy-like pastille was evaluated as a topical treatment for radiation-induced xerostomia in head and neck cancer patients. This local delivery system, which differs from systemically administered pilocarpine preparations, was developed to hopefully maximize the local response and minimize the systemic side effects. A prospective, randomized, double-blind, placebo-controlled trial was undertaken to determine objective and subjective efficacy in reversing the decrease in salivation. Forty previously irradiated patients received increasingly higher pilocarpine dosages in pastilles for 5 successive weeks. At each successive dose of pilocarpine, no significant increased salivation was noted. However, 25 (74%) of 34 patients reported that pilocarpine alleviated their subjective xerostomia. Topical pilocarpine administration has shown similar results to previous systemic delivery methods for radiation-induced xerostomia, but with improved patient tolerance.

Phenylephrine and the prevention of postoperative tympanostomy tube obstruction.

OBJECTIVE: To determine the efficacy of phenylephrine hydrochloride, a topical vasoconstrictor, in preventing tympanostomy tube obstruction. DESIGN: Prospective, randomized, double-blind, controlled trial of patients undergoing myringotomy with tympanostomy tube insertion. SETTING: Academic, tertiary referral medical center. PATIENTS: Two hundred eight patients were enrolled in the study; 157 patients (310 ears) returned for postoperative evaluation. INTERVENTIONS: Myringotomy with tympanostomy tube insertion was performed in all ears: 139 control ears received ototopical antibiotics and 171 treatment ears received ototopical antibiotics plus topical phenylephrine. MAIN OUTCOME MEASURE: Postoperative tympanostomy tube obstruction. RESULTS: The overall incidence of tympanostomy tube obstruction was 5.2%: 8.6% in the control group and 2.3% in the treatment group. The treatment group demonstrated an odds ratio of 0.25 (95% confidence interval, 0.08-0.78; P= .02). CONCLUSION: The use of phenylephrine following tympanostomy tube insertion greatly reduces the incidence of tube obstruction.

Effect of uvulopalatopharyngoplasty and genial and hyoid advancement on swallowing in patients with obstructive sleep apnea syndrome.

OBJECTIVE: Uvulopalatopharyngoplasty (UPPP) and genial and hyoid advancement (GHA) are surgical techniques for the treatment of obstructive sleep apnea. These techniques enlarge the oropharyngeal and hypopharyngeal airway, reducing collapse at these levels. This study evaluated the effect of these procedures on swallowing. METHODS: Fifteen patients who had undergone UPPP and GHA were evaluated with a modified barium swallow to assess biomechanical changes in swallowing. Specifically, velopharyngeal insufficiency; changes in tongue-base movement, laryngeal elevation, and closure; epiglottic movement; and pharyngoesophageal opening were examined. A brief swallowing questionnaire was administered to assess for subjective changes in swallowing. RESULTS: Nine of 15 patients demonstrated abnormal objective swallow, of whom 5 reported normal subjective swallowing. Six of 15 demonstrated normal objective swallowing. Of these, 5 reported subjective change. CONCLUSION: UPPP with GHA may alter biomechanical events during deglutition. However, little correlation exists between subjective symptoms and objective findings. Further studies that include preoperative and postoperative modified barium swallows are needed to identify a cause-and-effect relationship.

Pediatric vocal fold medialization with silastic implant: intraoperative airway management.

Vocal fold immobility accounts for 10% of all congenital laryngeal abnormalities, second only to laryngomalacia. Acquired unilateral vocal fold immobility (UVFI) is generally due to surgical trauma. The problems associated with this condition include a breathy dysphonia, weak cough, and aspiration. Treatment involves observation, voice and swallowing therapy, and various surgical options. Medialization laryngoplasty with silastic implant (ML-s) is a very successful procedure with consistent results in the adult population. It is usually done under local anesthesia with sedation to allow the voice to be monitored during the procedure. The surgeon can then fashion a custom implant or use a specific prefabricated implant. Additionally, use of the flexible fiberoptic nasopharyngolaryngoscope (FFNPL) allows the surgeon to see the endolarynx during the procedure, thus avoiding overmedialization and airway obstruction. Children, however, do not tolerate such invasive procedures under local anesthesia and sedation, have much smaller airways and, therefore, present several problems when addressing this problem surgically. Management of the pediatric airway during ML-s can be achieved using a laryngeal mask airway (LMA) and the FFNPL. While this does not allow the voice to be assessed intraoperatively, appropriate medialization of the vocal fold can be judged via the FFNPL, and airway obstruction avoided. ML-s using the LMA and FFNPL was performed in two children aged 8 and 4 years old. Both had excellent voice results and no complications. The details of these cases are reported. The literature on treatment of UVFI in children is reviewed, and practical and theoretical issues discussed.

Recurrent condyloma acuminatum due to piercing of the penis.

An unusual case of recurrent condyloma acuminatum in a tubular penile piercing scar is presented. This case documents a previously unreported dermatologic infectious sequela of this practice. We comment on complications of bodily and genital piercing.

The evaluation of unilateral vocal fold immobility: is chest X-ray enough?

Unilateral vocal fold immobility (UVFI) is a sign of underlying disease. No consensus exists regarding the appropriate evaluation. This study was performed to determine the ability of a chest radiograph (CXR) to limit further costly testing. The charts of 169 patients with previously undiagnosed UVFI were reviewed. In 113 patients the etiology was identified during the history and physical examination (H&P), or the H&P led to a directed evaluation. There were nine patients in whom the evaluation was incomplete. There were 47 patients in whom the etiology was not identified during the H&P. In 28 patients, the CXR identified the etiology, and in 16 cases the CXR ruled out an intrathoracic cause. There were three patients whose H&P and CXR did not identify their cervical etiology No patients had a thoracic etiology that was not identified by CXR. An algorithm was developed: If H&P fail to determine the etiology or to direct the evaluation, CXR is performed and followed by appropriate evaluation if positive. A negative CXR is followed with computed tomography (CT) of the neck from the skull base to thoracic inlet for right-sided UVFI and to the aortic triangle for left-sided UVFI. Other diagnostic studies are directed by signs and symptoms. A chest CT is not recommended unless there is clinical suspicion of a pulmonary or thoracic process.