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Biomedical subjects

R E McMahon

Publications and source records attributed to R E McMahon.

At least 19 recordsLinked to original sources
PubMed1998

A preliminary pilot study of treatment of thrombophilia and hypofibrinolysis and amelioration of the pain of osteonecrosis of the jaws.

OBJECTIVES: In a preliminary pilot study of 30 treatments in 26 patients with osteonecrosis of the jaws and chronic disabling facial pain, our specific aim was to determine whether, to what degree, and how safely therapy of hypofibrinolysis and thrombophilia would ameliorate the chronic pain associated with osteonecrosis of the mandible and maxilla. STUDY DESIGN: Thrombophilia was treated with Coumadin (DuPont) in 10 patients; hypofibrinolysis was treated with Winstrol (Sanofi-Winthrop) in 20 patients, including 4 who had mixed thrombophilia and hypofibrinolysis and had previously been treated with Coumadin. The initial treatment period was targeted to be 4 months. Each patient was asked to keep a daily written pain-relief numeric rating score and side-effects diary and to provide a summary pain-relief numeric rating score and side effects compilation for the total treatment period. RESULTS: There were 4 men and 22 women in the study group; their mean age was 49 +/- 11 years. The mean onset of their osteonecrosis pain was at age 45 +/- 12 years, and the mean duration of their facial pain prior to therapy was 4.5 +/- 4.2 years. Ten patients had one or more thrombophilic traits (there were two patients with protein C deficiency, five with resistance to activated protein C and/or the mutant Factor V Leiden gene, and four with high anticardiolipin antibodies). The 10 patients who were thrombophilic were treated with Coumadin (the international normalized ratio was targeted to 2.5-3.0) for 22 +/- 9 weeks. By self-reported pain-relief numeric rating scores, 6 of the 10 patients with thrombophilia (60%) had > or = 40% pain relief, 2 (20%) had no change, and 2 (20%) had increased pain (30% and 80% worse). Nine of the 10 patients with thrombophilia (90%) had no Coumadin-related side effects; 1 patient (10%) stopped Coumadin therapy (after 28 weeks) because of nosebleeds. Winstrol (6 mg per day) was used for 16 +/- 9 weeks in 20 patients with hypofibrinolysis, some of whom had one or more hypofibrinolytic traits (10 had high levels of plasminogen activator/inhibitor activity, usually accompanied by low stimulated tissue plasminogen activator activity; 13 had high Lp[a] lipoprotein). Of these 20 patients with hypofibrinolysis, 9 patients (45%) had > or = 40% pain relief, 3 patients (15%) had 20% to 30% relief, 5 patients (25%) had no improvement, and 3 patients (15%) had increased pain (30% worse, 60% worse, and 70% worse). Six of the 20 patients with hypofibrinolysis (30%) had no Winstrol-related side effects, while 14 (70%) had side effects that could be attributed to Winstrol, including weight gain, peripheral edema, increased facial and body hair, and acne--all of which were reversed within 6 weeks of stopping Winstrol therapy. CONCLUSIONS: We postulate that thrombophilia and hypofibrinolysis lead to impaired venous circulation and venous hypertension of the mandible/maxilla with subsequent development of osteonecrosis and chronic facial pain. In many patients, facial pain can be ameliorated by treating the pathogenetic coagulation defects with Coumadin or Winstrol. Large, double-blind, placebo-controlled crossover studies will be required in the future to validate these preliminary results and to determine whether pain relief with Coumadin or Winstrol justifies the risks and side effects associated with these medications, especially for long-term use, in osteonecrosis of the jaws.

Adult↗
PubMed1998

Exogenous estrogen may exacerbate thrombophilia, impair bone healing and contribute to development of chronic facial pain.

A 32 year old white female, in apparently good health, failed to respond to conservative wound care for alveolar osteitis after a routine mandibular first molar extraction. Curettage and biopsy of necrotic alveolar bone from the #30 socket escalated her pain such that hospitalization was necessary for pain management with intravenous morphine. Twelve months prior to admission she had been placed on exogenous estrogen (Premarin, 0.625 mg/day) after a partial oophorectomy. While hospitalized, she was found to have resistance to activated protein C (APCR). Premarin was discontinued. After discharge, weekly changes of an antibiotic impregnated dressing allowed for progressive regeneration of bone and epithelium with gradual reduction in her pain. She was found to be heterozygous for the mutant Factor V Leiden, a heritable factor for increased tendency to form thrombi, so-called thrombophilia. We speculate that the exogenous estrogen administration exacerbated the thrombophilia associated with the Factor V Leiden mutation by compounding the patient's resistance to activated protein C thereby contributing to her development of osteonecrosis and severe alveolar neuralgia.

Adult↗
PubMed1997

Heterozygosity for the Leiden mutation of the factor V gene, a common pathoetiology for osteonecrosis of the jaw, with thrombophilia augmented by exogenous estrogens.

We assessed whether heterozygosity for the thrombophilic Leiden mutation of the factor V gene (MFV) was pathogenetic for alveolar osteonecrosis of the jaw and chronic facial pain (neuralgia-inducing cavitational osteonecrosis (NICO)) in 89 patients with NICO. A second specific aim was to assess for thrombophilic synergism between exogenous estrogens and MFV for development of osteonecrosis of the jaw. MFV was found in 24% of the patients, 16 (21%) of 76 women and 5 (39%) of 13 men. The mutation was much less common in healthy normal controls: 3 (3%) of 101 women (chi2 = 14.8, p = 0.001) and 4 (3.7%) of 108 men (chi2 = 20.4, p = 0.001). Patients with and without MFV did not differ in tissue plasminogen activator activity, plasminogen activator inhibitor activity, proteins C and S, lipoprotein (a), or anticardiolipin antibodies (p > 0.05). Use of standard-dose oral contraceptives and/or postmenopausal estrogens before the development of NICO was more common in female patients with MFV (13 (81%) of 16) than in those without it (23 (38%) of 60; chi2 = 9.33, p = 0.002). When the thrombophilic effects of such exogenous estrogens were superimposed on the familial resistance to activated protein C associated with MFV, thrombophilia was augmented and the risk of osteonecrosis was increased. Since heterozygosity for this mutation occurs in at least 3% of unselected, healthy women, measurement of resistance to activated protein C and MFV would identify women at high risk for venous thrombosis and osteonecrosis, in whom use of oral contraceptives or postmenopausal estrogens might be contraindicated, while identifying a much larger group of women (approximately 97%) without the mutation whose risk from exogenous estrogens would be low.

Contraceptives, Oral↗
PubMed1996

The pathophysiology of alveolar osteonecrosis of the jaw: anticardiolipin antibodies, thrombophilia, and hypofibrinolysis.

We studied 55 patients (50 women, 5 men) with severe facial pain and biopsy-proven neuralgia-inducing cavitational osteonecrosis (NICO) of the alveolar bone of the jaws. Our aim was to assess the pathophysiologic contributions to NICO of anticardiolipin antibodies (aCLA), thrombophilia (increased tendency to intravascular thrombi), and hypofibrinolysis (reduced ability to lyse thrombi). Of the 55 patients, 43 (78%) had one or more tests positive for thrombophilia or hypofibrinolysis (or both), and only 12 (22%) were normal. Eighteen of 55 (33%) patients had high aCLA (> 2 SD above mean value for control subjects); immunoglobulin G (IgG) (p = 0.01) and immunoglobulin A (IgA)(p = 0.001) levels were higher in patients than in controls. The distribution of elevated aCLA immunoglobulin classes among patients was as follows: IgG alone, 5 (9%); IgA alone, 7 (13%); and IgM alone, 3 (5%). Three patients (5%) had high levels of both IgG and IgA aCLA. Other defects of the thrombotic or fibrinolytic systems in the 55 patients included high lipoprotein(a) in 36% (vs 20% in control subjects (p = 0.03)), low stimulated tissue plasminogen activator activity (tPA-Fx) in 22% (vs 7% in control subjects (p = 0.08)), high plasminogen activator inhibitor activity (PAI-Fx) in 18% (vs 8% in control subjects (p = 0.03)), resistance to activated protein C in 16% (vs 0% in control subjects (p = 0.007)), low antigenic protein C in 4+ (vs 0% in control subjects (p > 0.2)), and low antigenic protein S in 4% (vs 0% in control subjects (p > 0.2)). Anticardiolipin antibodies and other defects of the thrombotic and fibrinolytic systems appear to be common, potentially reversible pathogenetic risk factors associated with osteonecrosis of the jaw.

Adolescent↗
PubMed1996

Thrombophilia, hypofibrinolysis, and alveolar osteonecrosis of the jaws.

OBJECTIVES: Our specific aim in 49 patients (42 women, 7 men) with osteonecrosis of the jaw was to determine whether thrombophilia (increased tendency to intravascular thrombosis) or hypofibrinolysis (reduced ability to lyse thrombi) were associated with this regional avascular necrosis. STUDY DESIGN: Determinants of thrombosis and fibrinolysis were compared in healthy controls and in 42 women and 7 men who had biopsy-proven idiopathic osteonecrosis of the jaw with severe chronic jaw or facial pain syndromes and failure to respond to conventional medical and dental treatments. RESULTS: Of the 49 patients, 35 (71%) had thrombophilia or hypofibrinolysis and only 14 were normal. Thrombophilia as a sole coagulation defect was found in 10 patients, 7 with resistance to activated protein C and 3 with low protein C (deficiency of an antithrombotic protein). Hypofibrinolysis with low stimulated tissue plasminogen activator activity and high lipoprotein (a) (an atherogenic, hypofibrinolytic lipoprotein) were found as sole coagulation defects in seven and eight patients, respectively. Ten patients had mixed defects; 7 of these 10 had thrombophilia with resistance to activated protein C. Sinusoidal dilatation was a constant feature in maxillary and mandibular bone biopsies, suggesting venous occlusion with intramedullary hypertension. Marrow fibrosis and occasional fibrin plugs were additional microscopic features believed to impair venous drainage and to contribute to ischemic necrosis of the alveolar bone. CONCLUSIONS: Primary thrombophilia and hypofibrinolysis appear to be common, heritable, pathophysiologic risk factors for idiopathic osteonecrosis of the jaws. These coagulation defects may also contribute to alveolar neuralgia, atypical odontalgia and facial neuralgia, idiopathic trigeminal neuralgia, and to treatment failures so often encountered in patients with alveolar osteonecrosis and disabling chronic facial and jawbone pain syndromes.

Adult↗
PubMed1995

Local anesthetic effects in the presence of chronic osteomyelitis (necrosis) of the mandible: implications for localizing the etiologic sites of referred trigeminal pain.

The aims of this study were: (1) to demonstrate how reproducible variations in incomplete anesthesia of the inferior alveolar nerve can be used as a guide to locate the etiologic sites of referred trigeminal pain emanating from the mandible; (2) to describe the salient histopathologic features of a lowgrade, nonsuppurative osteomyelitis seen in this patient population. Forty-six patients with idiopathic facial pain were subjected to a specific protocol of local anesthetic injections to sequentially block branches of the mandibular nerve to determine the effects on his/her pain. If this significantly reduced or altered the pain on three separate appointments, then exploratory surgery was conducted near identified zones of unanesthetized gingiva. Blocking (92%), bridging (4%), and divergence (4%) were observed patterns of anesthetic resistance of the mucogingival tissues used to categorize the incomplete anesthesia. A 100% correlation was found between the identified zones of unanesthetized gingiva and the discovery of intramedullary pathology. Medullary fibrosis with ischemic and degenerative changes in the cancellous bone were common findings, along with chronic inflammatory cell infiltrates and clusters of lymphocytes. It is concluded that Ratner's method of diagnostic anesthesia be implemented when searching for occult pain producing pathology of the jaws.

Adult↗
PubMed1987

Compatibility of premixed theophylline and methylprednisolone sodium succinate intravenous admixtures.

The stability of theophylline supplied as a premixed injection and of methylprednisolone sodium succinate in admixtures containing both drugs was studied. Solutions containing theophylline in concentrations of 4.0 mg/mL and 0.4 mg/mL were used. Methylprednisolone sodium succinate was added to each solution to produce a final concentration of 0.5 mg/mL and 2.0 mg/mL of methylprednisolone alcohol, a pharmacologically active form of methylprednisolone sodium succinate. Each admixture was prepared in triplicate, and samples were kept at room temperature in glass containers. Immediately after admixture and at 3, 6, 12, and 24 hours, samples were visually inspected, tested for pH, filtered, and assayed in duplicate by high-performance liquid chromatography for theophylline concentration and for both methylprednisolone sodium succinate and methylprednisolone alcohol content. Control solutions containing only one of the two drugs were also tested. No visual changes were observed. The addition of theophylline in 5% dextrose injection to the methylprednisolone sodium succinate solutions resulted in decreased pH values for all solutions, which did not vary significantly throughout the study period. Theophylline concentrations did not change significantly compared with baseline. In solutions containing theophylline 0.4 mg/mL with either 2.0 or 0.5 mg/mL of methylprednisolone sodium succinate, less than 90% of the initial methylprednisolone sodium succinate concentrations remained at 24 hours. However, within three hours after admixture preparation, methylprednisolone alcohol was detected in those solutions in increasing concentrations. A commercial preparation of premixed theophylline in 5% dextrose injection in a concentration of 4 mg/mL or less can be mixed with methylprednisolone sodium succinate in a final concentration of 2 mg/mL or less and administered intravenously within 24 hours after mixing.

Chromatography, High Pressure Liquid↗
PubMed1981

Chemically-induced unscheduled DNA synthesis in primary rat hepatocyte cultures: a comparison with bacterial mutagenicity using 218 compounds.

The autoradiographic identification of unscheduled DNA synthesis (UDS) in primary cultures of adult rat hepatocytes (HPC) has been proposed as a predictive test for mutagens/carcinogens. To assess the predictive value of this test, results in the hepatocyte UDS assay were compared with data for bacterial mutagenicity using a modified Ames test. Over 200 compounds representing a variety of chemical classes consisting of procarcinogens, ultimate carcinogens, and noncarcinogens were tested in each system. The accurate discrimination of many carcinogens/noncarcinogens was demonstrated by both systems. The induction of UDS in hepatocytes showed an excellent correlation with bacterial mutagenesis in response to polycyclic aromatic hydrocarbons, aromatic amines, biphenyls, nitrosamines, carbamates, azo-compounds, acridines, halogenated compounds, nitrosureas, quinolines, pyridines, purines, pyrimidines, esters and carbamates. Nitrocompounds, although active in bacteria, were poor inducers of UDS. The results support the complementary and confirmatory nature of these tests for genotoxic chemicals and indicate the usefulness of the hepatocyte UDS system as a component in a battery of short-term predictive tests for mutagens/carcinogens.

Animals↗
PubMed1981

The mutagenicity of dialkylaminoalkyl chlorides in a battery of short-term assays.

Dialkylaminoalkyl chlorides, valuable chemical manufacturing intermediates, were evaluated for their mutagenicity in several short-term assays: The concentration gradient bacterial mutagen assay, the Ames test, the L5178Y mouse lymphoma cell assay, and the hepatocyte primary culture-DNA repair test. The dialkylaminoethyl chlorides were active in all test systems. The relative mutagenic potencies of the ethyl chlorides were similar in the bacterial tests and the genic potencies of the ethyl chlorides were similar in the bacterial tests and the L5178Y cell assay. The dialkylaminopropyl chlorides were weakly mutagenic in two Salmonella strains but were inactive in the other test systems. The purpose of the test battery used in these studies is to generate data on a test compound which could be used to make a rational prediction of the carcinogenic potential of the compound in test animals. On this basis, the results with the dialkylaminoethyl compounds suggest that if these agents which can form the aziridinium ion were evaluated in in vivo test there is a reasonable chance some would be found to be carcinogenic. Alternatively, the data on the dialkylaminopropyl chlorides indicate that they have a rather low carcinogenic potential.

Alkylating Agents↗