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Biomedical subjects

W W Montgomery

Publications and source records attributed to W W Montgomery.

At least 19 recordsLinked to original sources
PubMed1992

Chondroblastoma of the temporal bone. Case report and literature review.

Chondroblastoma is a rare tumor of bone that represents approximately 1% of all primary bone tumors. In the temporal bone, only 33 have been reported. We present a case of chondroblastoma of the temporal bone, followed by a literature review and analysis of reported cases. We conclude that the best chance for a prolonged disease-free interval is total excision using a combined otolaryngologic and neurosurgical approach.

Adolescent↗
PubMed1992

Preservation of hearing and facial nerve function in resection of acoustic neuroma.

The surgical results in 78 recent cases of total removal of unilateral acoustic neuroma in which an attempt was made to preserve cochlear function have been added to the authors' previous series of 66 cases to evaluate the factors influencing the ability to preserve useful hearing. Useful hearing was defined by speech reception threshold no poorer than 70 dB and a discrimination score of at least 15%. Analysis using a logistic regression model showed that certain preoperative clinical parameters such as tumor size, speech discrimination score, and gender were significantly correlated with hearing outcome. Favorable outcome was significantly correlated with smaller tumor size, higher preoperative speech discrimination score, and male sex. From this data, an explicit formula was devised for predicting hearing outcome for an individual patient. In four cases with useful hearing preserved, there was improvement of greater than 15 percentage points in speech discrimination scores. While preoperative auditory brainstem responses were not predictive of hearing preservation, monitoring of intraoperative auditory evoked potentials was predictive of hearing outcome in selected cases. Specifically, when wave V was unchanged at the end of the operation, even if it may have been transiently lost during surgery, useful hearing was invariably preserved.

Audiometry, Evoked Response↗
PubMed1992

Long-term hearing results in patients after surgical removal of acoustic tumors with hearing preservation.

Long-term hearing results are described in 18 patients after suboccipital removal of unilateral acoustic neurinomas. Follow-up ranged from 3.4 to 10.4 years with a mean of 5.4 years. Fourteen patients (78%) experienced no significant decline in long-term hearing. Four patients (22%) experienced a significant decline in long-term hearing as defined by a drop in pure-tone average (0.5, 1, and 2 kHz), or a significant decline in Speech Discrimination Scores (SDS). Changes in hearing did not correlate with tumor size, preoperative hearing, intraoperative change in hearing, the interval between initial symptoms and surgery, sex, or age.

Audiometry, Evoked Response↗
PubMed1991

Desensitization and functional antagonism by beta-adrenoceptor and muscarinic receptor agonists, respectively: a comparison with receptor alkylation for calculation of apparent agonist affinity.

1. Apparent affinity constants (KD) for prenalterol, an agonist of low intrinsic efficacy at beta 1-adrenoceptors in rat left atria, have been determined by use of receptor desensitization and functional antagonism induced by isoprenaline and carbachol, respectively. The values obtained have been compared to those values estimated with the irreversible beta-adrenoceptor antagonist, bromoacetylalprenololmenthane (BAAM). 2. The -log KD values for prenalterol estimated by desensitization or irreversible antagonism ranged from 6.8-7.1 and 6.2-7.1, respectively. 3. Carbachol produced functional antagonism of the response to prenalterol even though it was removed before addition of prenalterol. This effect was mediated by M2-muscarinic receptors. Pretreatment of animals with pertussis toxin did not affect the functional antagonism elicited by carbachol. The apparent KD value obtained after pre-exposure to carbachol (6.8) was similar to those estimated by use of either alkylation with BAAM or desensitization with isoprenaline (see above). 4. It is concluded that acute desensitization or functional antagonism of responses to agonists of low intrinsic efficacy provides a means to estimate apparent KD constants. This approach could be useful to characterize receptors for which an irreversible antagonist may not be available.

Adrenergic beta-Agonists↗
PubMed1991

Leiomyosarcoma of the trachea. Case report.

Leiomyosarcoma of the trachea is a rare primary tumor of the upper airway. Twelve cases have been reported in the English-language literature. Our experience with a patient with leiomyosarcoma of the cervical trachea is presented. The classic symptoms, diagnosis, and surgical management of this case are contrasted with those of the previously reported cases. The surgical technique used for our patient, primary tumor resection with skin grafting and placement of a Montgomery Laryngeal Stent, is a unique and effective treatment.

Adult↗
PubMed1991

Preservation of the facial nerve in the management of recurrent pleomorphic adenoma.

Whether to preserve or sacrifice a facial nerve involved with benign neoplasm is one of the most difficult intraoperative decisions confronting the head and neck surgeon. We reviewed 21 cases of recurrent pleomorphic adenoma treated with subtotal excision and facial nerve preservation, followed by postoperative radiation therapy. Of the 17 patients with microscopic residual tumor at completion of surgery, 16 (94%) remain free of recurrence with an average follow-up of 5.9 years. Only one of four patients (25%) with a large postoperative tumor load remains free of disease. Facial nerve function is normal in 20 of 21 patients. Preservation of the facial nerve with postoperative irradiation should be considered as an alternative to nerve sacrifice in selected cases of recurrent pleomorphic adenoma.

Adenoma, Pleomorphic↗
PubMed1991

Deciding on optimal management of supraglottic carcinoma.

The management of supraglottic carcinoma is controversial. Laryngectomy with or without a radical neck dissection as the sole therapy is usually inappropriate. After supraglottic partial laryngectomy plus neck dissection, many patients are troubled with aspiration and often do poorly if postoperative radiation therapy is administered. Likewise, advocating radiation therapy alone for all lesions is inappropriate, although conventional once-daily radiation therapy is highly effective in eradicating early supraglottic carcinomas. However, for large T3 and T4 lesions, local control is poor with conventional radiation therapy. Thus these advanced lesions have been managed by total laryngectomy plus radiation therapy. To avoid loss of voice, a program of accelerated split fractionated radiation therapy was initiated at Massachusetts General Hospital in 1979. The results have shown marked improvement in local control of most moderately advanced supraglottic carcinomas.

Combined Modality Therapy↗
PubMed1991

Steroid-induced visual recovery in fibrous dysplasia.

Fibrous dysplasia is a rare disorder of bone that may be associated with acute loss of vision. Surgical intervention is generally advocated and sometimes restores vision in these patients. We report a case of a patient with unilateral optic neuropathy from fibrous dysplasia who suffered two acute episodes of visual impairment. The first episode of vision loss was reversed by surgery and the second by corticosteroid treatment. A trial of corticosteroid therapy may be beneficial in cases of acute vision loss due to fibrous dysplasia.

Adult↗
PubMed1990

The interaction of parafluorohexahydrosiladiphenidol at muscarinic receptors in vitro.

1. The antagonistic actions of parafluorohexahydrosiladiphenidol (pFHHSiD) at muscarinic receptors has been studied in cardiac muscle, smooth muscle and cell culture preparations. In this paper, the classification scheme of Doods et al. (1987) is employed. This scheme is based upon differential affinities of muscarinic antagonists. pFHHSiD exhibited high pA2 values at M3 receptors mediating contractions of guinea-pig ileum and oesophageal muscularis mucosae (7.8 and 8.2 respectively) whereas low values were determined at M2 receptors mediating negative inotropic responses in guinea-pig atria (6.0). Intermediate pA2 values were determined at M1 receptors mediating contractions of the canine femoral and saphenous veins. 2. The pA2 values of pFHHSiD at receptors mediating endothelial-dependent relaxation of rat aortic rings, rabbit jugular vein and canine femoral artery (7.6-7.9) were similar to those determined on the ileum. However, the pA2 values of pFHHSiD at receptors mediating contractions of the guinea-pig trachea (7.1), which has been previously shown to possess M3 receptors, were different from those determined in the ileum. 3. The similarity in pA2 values of pFHHSiD between the M3 receptors in guinea-pig ileum and the receptors mediating endothelial-dependent relaxations provide further evidence for the role of M3 receptors in this vascular response. Taken together, pA2 values for pFHHSiD range from 7.1 to 8.2, depending upon the M3 preparation used. The selectivity of the compound therefore for the M3 versus the M2 muscarinic receptor ranged from 13 to 163 fold. 4. At muscarinic receptors mediating stimulation of phosphatidylinositol hydrolysis, pFHHSiD paradoxically displayed a high affinity for the M1 receptor in the SH-SY5Y cell line (pA2 = 7.9) as well as for the M3 receptor in the human astrocytoma (1321 NI cell line (pA2 = 7.6). The value at the M1 receptor in SH-SY5Y cells was greater than was observed at M1 receptors mediating contractions of both the canine saphenous and femoral veins (7.1). 5. pFHHSiD, therefore, clearly delineated M3 from M2 muscarinic receptors, whilst the separation between M1 and M3 receptors was variable. The reason for the anomalous affinity estimates in some functional studies remains unclear. These data indicate that the pA2 values for pFHHSiD appear to be tissue-dependent since the M3 selectivity varies according to the preparations studied. As a result the utility of pFHHSiD in muscarinic receptor classification is limited.

Animals↗
PubMed1990

Manual for use of Montgomery laryngeal, tracheal, and esophageal prostheses: update 1990.

This manual is designed to instruct the surgeon, the nurse, and, directly or indirectly, the patient on the updated usage of prostheses involved with reconstructive surgery of the larynx, trachea, and esophagus. The silicone tracheal Safe-T-Tube has been modified in an attempt to prevent its being displaced posteriorly into the trachea. The silicone tracheal cannula can be used in place of a tracheotomy tube unless there is aspiration or positive pressure breathing is required. Its success with sleep apnea has been especially gratifying. The salivary bypass tube and the esophageal tube continue to be of use in treating fistulas, strictures, and reconstruction of the cervical esophagus. The laryngeal keel and stent are described and illustrated for use with reconstructive surgery of the larynx.

Esophagus↗
PubMed1989

Osteomyelitis of the frontal bone.

Osteomyelitis of the frontal bone and its complications remain a diagnostic and therapeutic challenge to the head and neck surgeon. This paper will deal with the etiology, pathogenesis, diagnosis, and treatment of osteomyelitis of the frontal bone, and its complications and sequelae. Special emphasis is placed on techniques for repair of forehead defects.

Acute Disease↗
PubMed1989

Radiographic diagnosis, surgical treatment, and long-term follow-up of cholesterol granulomas of the petrous apex.

Cholesterol granuloma is an unusual lesion of the petrous apex. Accurate preoperative differentiation of the various lesions of the petrous apex by computed tomography scanning only has been difficult. We reviewed the clinical findings, computed tomography and magnetic resonance imaging scans, surgical approaches, and long-term follow-up in 10 patients with cholesterol granuloma of the petrous apex who were seen between 1971 and 1988. Headache and deficits of the 5th, 6th, 7th, and 8th cranial nerves were common presenting symptoms. Magnetic resonance imaging with special imaging techniques was accurate in diagnosing cholesterol granuloma in four patients preoperatively and three patients prior to revision surgery. The optimal surgical approach was chosen on the basis of clinical and radiographic findings and included the transsphenoidal, infralabyrinthine, transcochlear, and suboccipital routes. Our review reveals that magnetic resonance imaging is more specific than computed tomography in establishing a preoperative diagnosis and is also the technique of choice in follow-up. The long-term results are discussed.

Adult↗
PubMed1988

Differential effects of pertussis toxin on muscarinic responses in isolated atria and smooth muscle.

1. The effect of pretreatment with pertussis toxin has been studied on responses to muscarinic agonists in guinea-pig atria and smooth muscle in vitro. 2. 48 h after a single intravenous injection of pertussis toxin (3.2-100 micrograms.kg-1), muscarinic receptor-mediated negative inotropic responses in the atria were inhibited in a dose-dependent manner, with complete abolition of responses occurring after administration of 100 micrograms.kg-1. 3. In contrast, there was no effect on atrial positive inotropic responses to isoprenaline. In addition, no effect was observed on contractile responses to carbachol and pilocarpine in the ileum, trachea, oesophageal muscularis mucosae and urinary bladder, either in terms of potency or maximal response, at all dose levels of pertussis toxin studied. 4. It is concluded that muscarinic receptors in the atria, but not smooth muscle, are probably coupled to the inhibitory regulatory protein Ni, which is functionally inactivated by pertussis toxin. The differences in coupling between atrial and smooth muscle muscarinic receptors provide further evidence for muscarinic receptor heterogeneity in these two tissues.

Animals↗
PubMed1988

The interaction of methoctramine and himbacine at atrial, smooth muscle and endothelial muscarinic receptors in vitro.

1. The action of methoctramine and himbacine at muscarinic receptors has been studied using guinea-pig isolated trachea, oesophageal muscularis mucosae, paced left atria, and rat aortic preparations. 2. Methoctramine (1 x 10(-6)-3.2 x 10(-4) M), but not himbacine, elicited positive inotropic responses. These responses were enhanced by pretreating the animals with reserpine. The responses in reserpine-treated animals were not antagonized by phentolamine (1 x 10(-6) M) but were antagonized by propranolol (1 x 10(-6) M). 3. Methoctramine, but not himbacine, exhibited allosteric inhibitory effects at cardiac muscarinic receptors, resulting in a curvilinear Schild plot. Deviations from competitive antagonism were also observed in combination dose-ratio experiments using atropine and methoctramine. At 1 x 10(-6) M, the pKB value for methoctramine was 7.88 +/- 0.15 (mean +/- s.e.mean, n = 5). The pA2 value for himbacine at cardiac muscarinic receptors was 8.52 +/- 0.06 (n = 3). 4. At tracheal and oesophageal muscularis mucosal smooth muscle receptors, the Schild plots for both antagonists were linear. The pA2 values for methoctramine at receptors in these two preparations were similar (6.08 +/- 0.05 and 6.03 +/- 0.09 respectively, n = 4) and were approximately 60 fold less than those values observed at atrial receptors. Himbacine, also exhibited similar values at muscarinic receptors in the trachea and oesophageal muscularis mucosae (7.61 +/- 0.05 and 7.57 +/- 0.04 respectively, n = 4). 5. Muscarinic receptors mediating relaxation of the rat aortic endothelium exhibited pA2 values for methoctramine (5.87 +/- 0.12, n = 6) which were similar to those observed in the smooth muscle, but not the atria. The pA2 values for himbacine at endothelial muscarinic receptors were approximately 0.5 pA2 units lower than those observed at muscarinic receptors in smooth muscle (6.92 + 0.80, n = 6). In addition, the Schild slopes for methoctramine and himbacine at these receptors were significantly (P < 0.05) less than unity. 6. Methoctramine, and to a lesser extent himbacine, are potent and selective antagonists for cardiac muscarinic receptors. However, caution should be used in interpretation of the data with methoctramine in view of the inhibitory allosteric properties and direct inotropic actions of this compound.

Alkaloids↗
PubMed1988

Negative and positive inotropic responses to muscarinic agonists in guinea pig and rat atria in vitro.

In the guinea pig atria, carbachol, acetylcholine and bethanechol elicited negative inotropic and positive inotropic effects. In the rat atria, a negative inotropic response occurred, but the positive inotropic response was small. The positive and negative inotropic responses to carbachol and bethanechol (but not acetylcholine) were unaffected by pretreating the animals with reserpine and were antagonised by pirenzepine with pKB values of 6.7. Pretreatment with pertussis toxin abolished the negative inotropic responses, but was without effect on the positive inotropic responses in the guinea pig. Pretreatment of rats with pertussis toxin abolished the negative inotropic response and enhanced the positive inotropic response. The positive inotropic response was attenuated by pretreatment with dietary lithium for 2 weeks, whereas no effect was observed on the negative inotropic response. Negative and positive inotropic responses to muscarinic agonists in these species are mediated directly through an M2 muscarinic receptor. The ability of dietary lithium to selectively inhibit the positive inotropic response may provide evidence for the involvement of inositol phospholipid hydrolysis in this effect.

Animals↗
PubMed1987

Differential effects of pertussis toxin and lithium on muscarinic responses in the atria and ileum: evidence for receptor heterogeneity.

Pretreatment with pertussin toxin was shown to inhibit selectively muscarinic responses in the atria, but have no effect on responses in the ileum. The converse was true when the animals were pretreated with lithium. These data are consistent with the hypothesis that muscarinic receptors in the atria are coupled to an inhibition of adenylate cyclase, whilst those in the ileum are coupled to inositol phospholipid hydrolysis and indicate differences in the muscarinic receptors in these two tissues.

Adenylate Cyclase Toxin↗