Glutamate release in the ventromedial hypothalamus of the female rat during copulation: modulation by estradiol.

Binding of glutamate or its ionotropic receptor agonists in the ventromedial hypothalamus (VMH) of female rats inhibits both appetitive and consummatory aspects of sexual behavior. Because vaginocervical stimulation activates glutamate neurons in the VMH, and administration of estradiol benzoate (EB) and progesterone (P) delays this effect, the present study examined the effects of hormonal priming on glutamate release within the VMH of female rats paired with sexually vigorous males. Ovariectomized, sexually experienced rats were implanted with guide cannula aimed at the ventrolateral VMH, through which microdialysis probes were inserted prior to testing. Females were assigned randomly to one of three hormone treatment conditions: EB+P, EB alone, or the oil vehicle. Testing was conducted over 5h, including a 120-min period of habituation to the testing chamber, a 60-min period of baseline sample collection, and a 120-min period during which a sexually vigorous male was introduced into the testing chamber. Dialysates were collected every 20min during the test and were analyzed for glutamate using HPLC. Females primed with oil had large and significant increases in glutamate release from baseline once the male was introduced to the chamber. Treatment with EB alone decreased glutamate release in response to male cues. Although treatment with EB+P did not differ significantly from EB alone, the degree of reduced glutamate release was less than with EB alone. These results indicate that priming with EB reduces glutamate transmission in the VMH in response to male cues. Taken together with our previous findings, estradiol blunts the activation of glutamate neurons in the VMH thus allowing female rats to copulate.

Effects of Boundaries on Pattern Formation: Catalytic Oxidation of CO on Platinum.

The effect of boundaries on pattern formation was studied for the catalytic oxidation of carbon monoxide on platinum surfaces. Photolithography was used to create microscopic reacting domains on polycrystalline foils and single-crystal platinum (110) surfaces with inert titanium overlayers. Certain domain geometries give rise to patterns that have not been observed on the untreated catalyst and bring to light surface mechanisms that have no analog in homogeneous reaction-diffusion systems.

Toward organism identification through analysis of bacterial colonies.

The clinical problem of bacterial identification has been approached by applying pattern-recognition techniques to multi-wavelength surface-scattering and reflectance data derived from real-time scans of isolated colonies. Preliminary results, obtained from blood-agar plates inoculated with a mixture of staphylococci, streptococci and escherichieae, indicate that these organisms can be differentiated with better than 90% certainty, provided the colonies are physically separated and their growth conditions closely controlled. Data collection and classification characteristics of the experimental system are briefly described; it is felt that the technique, possibly expanded to include boundary characteristics of the colonies, may offer a viable means of identifying clinically important bacteria.

Giant cholesterol cysts of the petrous apex: radiologic features.

Four cysts are described that expanded and destroyed the bone of the petrous apex. All patients with these cysts had a sensorineural hearing loss. Mild symptoms referable to cranial nerves VI, VII, IX, X, XI, and XII were seen also. The cysts range in size from 1.5 X 1.5 X 3 cm to 5 X 5 X 6 cm. Grossly and histologically, they were distinct from any lesions seen previously. The lesions were large and contained glistening brown, watery fluid filled with cholesterol crystals. The cyst wall was predominantly fibrous tissue without an epithelium. Minimal chronic inflammatory change and granuloma formation were present within and just outside the cyst wall. These cysts have been described as mastoid cysts, epidermoids, mucoceles, and cholesterol granulomas; until now, they have not been recognized as a single distinct entity. A name emphasizing the pathologic characteristic of the lesion, giant cholesterol cyst, has been suggested. Distinguishing them from other petrous apex lesions preoperatively is difficult, but if the cystic nature of the lesion can be recognized or at least anticipated, more conservative surgery, such as simple drainage versus a more radical procedure, may be possible.

Breast conserving surgery in the management of in situ breast carcinoma.

In a retrospective review of 73 patients with in situ breast carcinoma seen in the Combined Breast Clinic at the Royal Marsden and St. George's Hospitals between 1969 and 1988, 20 (27%) were found to have in situ lobular and 53 (73%) in situ intraduct carcinoma. Of 19 patients with in situ lobular carcinoma treated by breast conserving surgery alone there were three (16%) recurrences of in situ lobular carcinoma and one (5%) of infiltrating carcinoma after a mean follow-up period of 65.8 months. Of 53 patients with in situ intraduct carcinoma, 37 were treated by breast conserving surgery alone and in this group there were 14 (38%) recurrences, of which seven (19%) were in situ intraduct and seven (19%) were infiltrating carcinoma, after a mean follow-up of 96.5 months. Following successful salvage there were no breast cancer related deaths in either group.

Bilateral carcinoma of the breast.

In a retrospective review of 2820 patients with breast carcinoma seen at the Combined Breast Clinic of St George's Hospital over a 23-year period 101 cases were bilateral of which 52 (1.8%) presented synchronously and 49 (1.7%) metachronously. Twenty deaths occurred in the synchronous group after a mean follow-up of 56.2 months and 15 deaths in the metachronous group after a mean follow-up of 48.5 months following diagnosis of the second tumour. If timed from initial presentation patients with metachronous tumours fared better than those with unilateral disease (P < 0.01). There was no significant difference in survival between patients with metachronous (if timed from the second tumour), synchronous or unilateral breast carcinoma.

The jugular bulb: its anatomic and clinical considerations in contemporary otology.

Advances in neurotologic diagnosis and surgery has pointed to the need for a complete reassessment of the relationship and significance of the jugular bulb and sigmoid sinus is discussed and selected temporal bone sections presented to illustrate the varying locations of the jugualr bulb. Considerations in differential diagnosis are presented and examples of surgical procedures are discussed wherein the jugular bulb was encountered and the methods of management are detailed in these instances.

Human incus long process depressions in the surface of the normal ossicle.

Depressions in the bone surface of the normal human incus long process are found with great frequency. This paper reviews the frequency and distribution of these depressions, discusses their histologic appearance, and speculates upon their significance. While their clinical significance is unclear, they may be related to several conditions encountered in otologic practice.

Human stapes crura: surface bone architecture: scanning electron microscopic findings.

Human stapes crura obtained at the time of stapedectomy for clinical otosclerosis have been studied after removal of the mucosal and periosteal layers by treatment with hydrogen peroxide and ultrasonification. With the scanning electron microscope, four basic architectural patterns are evident: honeycomb, fibrillar, compact and pitted. The significance of these patterns is as yet unclear, but they do appear to be in intimate relationship one to another and perhaps are varying stages in a single process.

Post-traumatic cholesteatoma of the external auditory canal.

Post-traumatic cholesteatoma of the external auditory canal is a rare condition which is not mentioned in any of the American or British otological reference works. Three cases are described, and the pathogenesis, management, and medico-legal implications discussed.

Surgical management of Meniere's disease with endolymphatic sac decompression by wide bony decompression of the posterior fossa dura: technique and results.

The results of wide bony decompression of the posterior fossa in 49 consecutive individuals with idiopathic unilateral Meniere's disease are reported. These results are similar to many previously published series, 71% of individuals are free of vertigo and 86% have unchanged or improved hearing. Utilizing the classification proposed by the American Academy of Ophthalmology and Otolaryngology, 73% fell into Class A, B, or C with relief of vertigo. These results together with the low complication rate encourages us to consider surgery at an earlier date, hoping to stabilize hearing at a more useful level and to relieve vertigo.

Salivary gland choristoma of the middle ear: a case report and review of the literature.

Salivary gland choristomata are heterotopic rests which have rarely been reported in the middle ear. A case report of a salivary gland choristoma of the middle ear is presented and the literature reviewed. The frequent association of ossicular chain and facial nerve anomalies is emphasized.

Atelectatic tympanic membrane reversal by nitrous oxide supplemented general anesthesia and polyethylene ventilation tube insertion. A preliminary report.

In certain instances an adherent atelectatic tympanic membrane (Sade Stage IV) may be successfully elevated off the promontory and ossicles by the use of nitrous oxide anesthesia and restored to a normal position and configuration by polyethylene ventilation tube insertion. Criteria of reversibility and long term follow-up of the tympanic membranes so restored remain to be elucidated.

Transmastoid labyrinthectomy indications. Technique and early postoperative results.

Persistent labyrinthine symptoms may manifest as unsteadiness veering or frank rotational vertigo. When these symptoms are resistant to medical therapy and are associated with hearing in the involved ear which is not of a serviceable level, then a transmastoid labyrinthectomy may be of value in ridding the individual of this disability. We have found that this operation may be performed expeditiously and safely; and if the entire vestibular epithelium is removed, the results of surgery are effective and predictable.

Patterns of vestibular function following vestibular nerve section.

Bithermal caloric irrigations, low-frequency rotational chair stimulation, and posturography were performed on 20 patients before and after vestibular nerve section. Twelve patients demonstrated acute postoperative spontaneous nystagmus and rotational vestibulo-ocular reflex (VOR) asymmetry. Eight patients demonstrated minimal acute postoperative spontaneous nystagmus and VOR asymmetry. Four patients had suppression of all vestibular function characterized by an absent contralateral caloric response, low VOR gain, and falls on posturography when required to rely solely on vestibular input to maintain posture. Four patients had a severe preoperative vestibular loss and no acute change in vestibular function following surgery. Over time, 5 patients continued to manifest elevated spontaneous nystagmus, 2 patients manifested a persistent rotational VOR asymmetry, and 5 patients exhibited a return of caloric function in the operated ear. It is suggested that multiple clinical factors contributed to the variable vestibular responses demonstrated in this study.

Clinical assessment of postural stability following vestibular nerve section.

Little is known about the recovery of postural control in patients following acute vestibular loss. This paper reports on the results of moving-platform posturography to assess the recovery of postural stability in 24 patients following vestibular nerve section. Posturography was abnormal prior to surgery in 17% of the patients. Seven days following surgery, 44% of the patients demonstrated vestibular deficit patterns, while 56% of the patients had normal posturography. Posturography was normal in all patients 1 month following surgery. Abnormal posturography was subsequently noted in 21% of the patients between 3 and 20 months following surgery. Each of the patients with abnormal preoperative posturography subsequently demonstrated abnormal late postoperative posturography. These results suggest that perioperative posturography may be useful in the evaluation and counseling of patients considering ablative vestibular surgery.

Ear-eye reflexes while riding in a car.

Persons with diminished or absent vestibulo-ocular reflexes (VORs) are thought to have difficulty with ocular stabilization during sufficiently rapid head movements. This suggests the hypothesis that labyrinthine defective individuals might have impaired visual abilities when in a moving motor vehicle. Ten licensed drivers likely to have abnormal VORs were recruited to assess this possibility. Their labyrinthine function was indexed by measurements of ocular counterroll responses to static head tilt and the nystagmus induced with caloric stimulations. Each person was evaluated on a visual task, i.e., answers to questions about alphanumeric information read from a stationary sign while sitting still and while riding in a car. Comparisons of vision scores tend to be lower in the moving than in the still condition. Furthermore, these decrements appear more closely related to the magnitudes of ocular counterroll than to the caloric reflexes. These results have implications concerning otolithic vs. semicircular canal function, vehicle operations by vestibular-impaired individuals, and evaluations of clinical treatments which employ vestibulotoxic drugs.

Intralabyrinthine schwannoma.

The diagnosis of intralabyrinthine schwannoma has been made either accidentally at the time of surgery or at postmortem examination. Brain stem evoked response audiometry and computerized tomography do not add to our ability to make this diagnosis clinically. A case is presented of an intralabyrinthine schwannoma found at the time of transmastoid labyrinthectomy. The literature is reviewed and a composite clinical picture is presented.

Intraoperative facial nerve monitoring: a comparison of stimulating electrodes.

Preservation of the facial nerve during acoustic neuroma resection may be enhanced by the use of intraoperative electrical stimulation. Although stimulation of the extratemporal facial nerve is an effective and established procedure, anatomic differences of the intradural facial nerve and its microenvironment demand more exacting stimulus protocols. The absence of epineurium may make the intradural nerve more susceptible to mechanical or electrical trauma while intermittent pooling of cerebrospinal fluid (CSF) at the cerebellopontine angle may shunt current away from nerve. Four stimulus configurations were examined under varying conditions simulating CSF pooling. The results indicated that: 1. insulation of stimulating electrodes prevents CSF current shunting and allows utilization of a constant current source, and 2. monopolar and bipolar configurations demonstrate significantly different electrical characteristics which may be employed selectively based upon specific clinical goals.

The giant cholesterol cyst of the petrous apex: a distinct clinical entity.

The giant cholesterol cyst (GCC) of the petrous apex may now be considered a distinct clinical entity and should be considered in the differential diagnosis of lesions of the midcranial skull base. This benign cystic lesion of the petrous apex gradually enlarges and may produce progressive bone erosion and serial neurologic deficits of the cranial nerves within the temporal bone and jugular foramen. We report here five instances of this lesion (3 patients with unilateral and 1 patient with bilateral petrous apex lesions) and describe the natural history, diagnostic evaluation, pathology, and surgical management.