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Biomedical subjects

G W Miller

Publications and source records attributed to G W Miller.

At least 19 recordsLinked to original sources
PubMed1992

Evidence of a neurogenic component during IgE-mediated inflammation in mouse skin.

IgE-mediated inflammation was measured in mouse footpads that lacked sciatic innervation. Mice were passively sensitized with a monoclonal antibody, IgE anti-dinitrophenol, or were immunized for specific IgE production. Antigen-induced swelling in the denervated footpads was reduced 23-39% when compared to sham or untreated controls. Reduced IgE-mediated swelling responses were attributed to the loss of a mast cell-nerve interaction and not to blood vessel sensitivity to vasoamines. Furthermore, electrical stimulation of the distal segment of the sciatic nerve completely restored IgE-mediated inflammation. These data provide in vivo evidence that peripheral nerves participate in cutaneous IgE-mediated swelling reactions with the net effect of increasing inflammation.

Analysis of Variance↗
PubMed1992

Effects of phosphate loading on metabolic and myocardial responses to maximal and endurance exercise.

Six trained male cyclists and triathletes participated in a double blind study to determine the effects of phosphate loading on maximal and endurance exercise performance. Subjects ingested either 1 gm of tribasic sodium phosphate or a glucose placebo four times daily for 3 days prior to performing either an incremental maximal cycling test or a simulated 40-km time trial on a computerized race simulator. They continued the supplementation protocol for an additional day and then performed the remaining maximal or performance exercise test. Subjects observed a 17-day washout period between testing sessions and repeated the experiment with the alternate supplement regimen in identical fashion. Metabolic data were collected at 15-sec intervals while venous blood samples and 2D-echocardiographic data were collected during each stage of exercise during the maximal exercise test and at 8-km intervals during the 40-km time trial. Results indicate that phosphate loading attenuated anaerobic threshold, increased myocardial ejection fraction and fractional shortening, increased maximal oxidative capacity, and enhanced endurance performance in competitive cyclists and triathletes.

Adult↗
PubMed1979

Glomus tumor of the middle ear: origin, symptomatology, and treatment.

The glomus tumor is considered to be the most common of all tumors that involve the middle ear. This report defines the glomus tumor and discusses the symptomatology of the tumor with respect to the various developmental courses it may follow. Forty clinical cases of glomus tumor are reviewed, with emphasis upon the incidence of the tumor and its symptoms, including the audiological manifestations noted in this series of cases. Current medical management of the glomus tumor recommends surgical removal of the lesion when possible; however, irradiation and embolization of the tumor may also be considered when its invasion into surrounding structures has been extensive. The pathology and its treatment may have marked temporary or permanent effects upon the hearing of the patient, and the importance of ongoing audiological management is therefore emphasized.

Acoustic Impedance Tests↗
PubMed1979

Tuning fork decay.

Tuning fork tests are used routinely by many otologists. A different group of otologists find the tests inconsistent and unreliable. This controversy has probably developed because the audiometer has replaced the tuning fork in hearing measurement. As a result, the art of use of the tuning fork is poorly learned. This study examines decay, one of the physical parameters of tuning forks. Measurements of acoustic (sound wave) and vibration (stem movement) decay were made. Alteration in decay due to pressure changes on the fork stem were studied. Acoustic signals were generated in an anechoic chamber. Vibration measurements were obtained using an artificial mastoid. Analysis of the signals was accomplished by a system of amplifiers, filters, tape recorders, and a graphic recorder. Tuning fork sound decay is a property of the instrument which occurs every time the fork is struck. The decay is a constant in decibels per second. The acoustic mode and the vibration mode decay at similar rates for the same fork. The strike frequency (a higher frequency than the fundamental produced when the fork is struck) also has a constant decay rate in decibels per second, and it is reported here for the first time. Force of 800 gm. and less applied to the bottom of the stem in vibration measurement caused minimal decay constant changes. When the physical parameters of the tuning fork (including this information on damping) are fully studied, tuning fork testing should become more of a science and less of an art.

Hearing Disorders↗
PubMed1979

Hypermobility of the incudostapedial joint: a clinical entity.

During exploratory tympanotomy for conductive deafness, the surgeon is occasionally perplexed to find no apparent cause for the air-bone gap. This unexplained deafness has been called "inner ear conductive hearing less" because of the apparent absence of pathology in the middle ear. The incudostapedial joint was studied in 68 vertically sectioned temporal bones and the anatomy is presented. Varying amounts of laxity is observed in the normal joint capsule at the time of surgery. A theory is suggested in which an elongated capsule allows incus motion without energy transmission to the stapes. It is proposed that hypermobility of the incudostapedial joint may exist and explain conductive hearing loss of undetermined etiology.

Audiometry↗
PubMed1978

Simultaneous complementary idiotypic responses: absence of reciprocal regulation.

Complementary antibodies, i.e. antibodies having combining site structures which are at least partially directed against each other, were induced in A/He mice by immunization with phosphorylcholine (Pc) coupled to keyhole limpet hemocyanin or with the Pc-binding IgA myeloma protein, HOPC-8 (H8). Both responses were monitored by enumerating plaque-forming cells and assaying serum antibody levels to Pc and H8. Prior immunization with H8 markedly suppressed subsequent immunization with Pc and vice versa; neither plaque-forming cell response was diminished, however, when mice were immunized simultaneously with Pc and H8. Experiments were designed to determine if the absence of reciprocal regulation was due to change in idiotypes. This was determined by measuring inhibition of plaque formation using complementary antibody. Plaque formation by cells was equally inhibited by high dilutions of the appropriate complementary antibody whether cells were from mice immunized with one, the other, or both antigens. Thus, the absence of regulation could not be accounted for by emergence of different idiotypes. Interestingly, sera from mice immunized to have high responses to both antigens were relatively ineffective in inhibiting plaque formation or suppressing immunization to Pc. However, such sera contained complexes of the complementary antibodies; apparently antibody to Pc in such sera quenches or neutralizes the activity of anti-H8 antibody. But the formation of complexes, at least measurable levels of circulating complexes, must be a result rather than the cause for the absence of reciprocal regulation, since regulation was also absent when immunization to Pc was manipulated so that responses were too low to result in detectable levels of circulating antibody to Pc. It is proposed that simultaneous complementary responses may occur in nature to other antigens and antibodies, and that such simultaneous responses may cause pathologic changes.

Animals↗
PubMed1978

Preservation of hearing in tumors of the internal auditory canal and cerebellopontine angle.

One hundred thirty-nine tumor removals are reviewed with special interest in ten attempts to save hearing. Three patients with bilateral tumors had some hearing preserved. One of these individuals had a 1 cm tumor removed and his postoperative SRT and discrimination scores were the same as his preoperative ones. Overall, the authors were able to maintain some hearing in six out of ten attempts. While there is no question that patients with bilateral tumors benefit from residual hearing, this is not always true in unilateral cases. The suboccipital and middle fossa procedures are discussed as well as the relative merits of each approach in the preservation of hearing. The total series (139 tumors) is discussed in detail regarding results and complications.

Adolescent↗
PubMed1978

Surgery of the skull base.

Tumors involving the base of the skull are often occult and may become quite large before detection is possible. Symptomology varies depending upon the nature of the tumor and its placement. These neoplasms have frequently been considered inoperable simply because of their location, but in recent years microsurgical technique and high speed air drills have allowed the modern temporal bone surgeon to gain improved access to the skull base. A wide variety of surgical approaches to tumors in this area have been described in the past 20 years: translabyrinthine, middle fossa, transcochlear, retrolabyrinthine, retrosigmoid, transpalatal-transclival, and through the jugular bulb. The purpose of this paper is to review the indications, complications, and results of each of these procedures in relation to specific tumors involving the skull base. Case reports illustrate the diagnosis and surgical management of a variety of unusual neoplasms, including an extradural meningioma of the temporal bone and clivus, a low grade squamous cell carcinoma on the tegmen in a radical cavity, a large primary cholesteatoma, an osteoblastoma of the temporal and occipital bones, an XIth nerve neuroma in the jugular bulb area, and an osseous hemangioma involving the facial nerve at the geniculate ganglion.

Adolescent↗
PubMed1978

Acoustic neuroma: results of brain stem evoked response audiometry.

Brain stem evoked response (BER) audiometry presents abnormal findings in patients with acoustic neuromas. The test involves averaging of recordings at the vertex as sound-triggered nerve impulses travel from the cochlea to the brain stem. From the time the sound stimulus arrives at the cochlea until it reaches the first major brain stem synapse (within 10 milliseconds), five major waves have been identified as typical of normal averaged responses. Abnormality in the cochlea or eighth nerve causes specific changes in pattern, primarily in wave latency. These latency shifts can be used to predict the site of the lesion. In evaluating 17 lesions of the cerebellopontine angle, BER audiometry was accurate in the diagnosis of all of the tumors. This diagnostic tool should play a prominent role when acoustic tumor is suspected.

Adolescent↗
PubMed1978

The immune response in NZB mice of different ages to thymus-dependent and thymus-independent phosphorylcholine antigens.

This study was designed to examine aberrations of immune responses in autoimmune NZB strain mice during ageing, at the level of individual B cell clones. The response to phosphorylcholine (PC) was chosen because murine responses to PC are restricted to a few B cell clones and can be characterized with idiotypic markers. Responses to both thymus-dependent (TD) and thymus-independently (TI) PC-containing antigens were measured in mice ranging from 1 to 62 weeks of age. We found that: (1) TD responses to phosphorylcholine keyhole limpet haemocyanin (PC-KLH) decreased markedly (about 17-fold) between 28 and 62 weeks of age. TI responses to the R36a strain pneumococcus decreased only slightly during the same period. (2) The PFC responses to both antigens became markedly prolonged in mice older than 24 weeks. (3) The NZB response to either antigen is essentially monoclonal, as measured by inhibition of PFC with specific anti-idiotype serum and PC hapten. No age-related alteration in avidity or idiotype expression was observed. Our results demonstrate that no aberrant PC-reactive B cell clones appear in old NZB, and lend support to the notion that the abnormalities observed are due to defective regulatory mechanisms.

Aging↗
PubMed1977

The effect of cytochalasin B on the endosteal lining cells of mammalian bone. A scanning electron microscopic study.

The lining osteoblasts of the rat tibial endosteum were treated for various times (between 1 and 60 min) and increasing doses (3.87-38.7 microgram/ml) with the macrolide fungal metabolite cytochalasin B (CB). Dimethylsulfoxide (DMSO) served as the vehicle for CB and was administered to control tissues. An in vitro incubation system and scanning electron microscopy (SEM) were used to evaluate the effects of CB. The drug initiated cell rounding (contraction), nuclear protrusion, bleb formation, and the subsequent clustering of blebs and microvilli into aggregates. All CB-induced aberrations of the surface structure were readily reversible when tissues were washed with CB-free media. DMSO had no significant effect on cell surface morphology. The reversible structural changes brought about by CB are explained in terms of alterations of the subplasmalemmal cortical microfilament system of osteoblasts. The potential use of CB in evaluating the bone cell cytoskeleton and its relationship to the physiology of the cellular functional membrane (endosteum) of bone is discussed.

Animals↗
PubMed1977

Diagnosis and management of cochlear hydrops.

In an early case of cochlear hydrops, the symptoms of a mild pressure sensation or fullness in the involved ear may be mistaken for a blocked eustachian tube. More severe cases demonstrate a true sensori-neutral hearing loss that fluctuates. Tinnitis is usually present during the attack and will often subside when the hearing returns to normal. The neurotologic evaluation is negative and attempts to establish an etiology are seldom fruitful. The treatment is usually medical, and empirically, these individuals are treated with diuretics, low salt diet, and vasodilators. It is felt by most investigators that cochlear hydrops is an early form of Ménière's disease, and over a long period of time these individuals may develop vertigo as a complaint. The purpose of this paper is to discuss this interesting form of Ménière's disease in detail concerning etiology, physiology, diagnosis, and treatment. A small series of patients who have undergone the subarachnoid endolymphatic sac procedure will be reported according to the guidelines set forth by the Committee on Hearing and Equilibrium of the American Academy of Ophthalmology and Otolaryngology. Based on the result in these patients, it would appear that this procedure should be considered in those individuals who are refractory to medical management. There is convincing evidence that the shunt does stabilize the hearing in many instances.

Cochlea↗
PubMed1977

Middle fossa vestibular nerve section in the management of Ménière's disease.

The triad of fluctuating hearing loss, tinnitus, and episodic attacks of vertigo known as Ménière's disease can be a frustrating therapeutic problem. While most patients respond to a medical regime consisting of a low salt diet, diuretics, diazepam, and propantheline bromide, there is a significant group who remain refractory to conservative management. These individuals either continue to experience their distressing symptoms or undergo some type of surgical procedure in an attempt to seek relief. There are a multitude of such techniques available to the otologic surgeon and he must make the decision as to which procedure is best for any given individual. The authors' employ three surgical approaches for the management of Ménire's disease. These are the translabyrinthine labyrinthectomy, the endolymphatic subarachnoid shunt, and the middle fossa vestibular nerve section. In this paper the indications for surgery, technique, results and complications are covered in detail. Thirty-one patients are reviewed who have been followed from one to four years postoperatively. Seventeen had total and 14 had superior vestibular nerve sections. The results were much better in the total group, as 94 percent had complete relief of vertigo and 76 percent were able to maintain their preoperative hearing level. The authors feel the middle fossa vestibular nerve section is a valuable addition to the otologist's armamentarium in the treatment of the patient who is refractory to medical management.

Adult↗
PubMed1977

Surgical management of Ménière's disease with the endolymphatic subarachnoid shunt: A five-year study.

The majority of individuals with Ménière's Disease can be successfully managed by medical means; however, there are some patients who become refractory to this form of therapy. It is this group of patients who are candidates for some type of surgical procedure. This paper reviews 109 patients who underwent 112 endolymphatic subarachnoid shunt procedures for the control of their Ménière's Disease. Medical therapy, indications for surgery, surgical technique, results, and complications are covered in detail.

Adult↗