PubMed Health⌕ Search

Biomedical subjects

M J Buckley

Publications and source records attributed to M J Buckley.

At least 73 records · Page 4Linked to original sources
PubMed1997

Changes in facial movement after maxillary osteotomies.

PURPOSE: Determine changes in facial movement while smiling after maxillary Le Fort I osteotomies. MATERIALS AND METHODS: Twenty patients (ages 15 to 38) treatment-planned for maxillary Le Fort I osteotomies were divided into two groups. Group A consisted of 10 patients who underwent superior and/or posterior positioning of the maxilla. Group B consisted of 10 patients who underwent anterior and/ or inferior repositioning of the maxilla. All patients underwent preoperative and postoperative (3 to 8 months) videographic analysis of a maximal closed mouth smile by the Johnson Maximal Static Response Assay, evaluating four landmarks around the mouth and nose (alar base--A, cheilion--C, labrale superioris--Ls, and intermediate between cheilion and labrale superioris--Im). RESULTS: Group A was noted to have a statistically significant decrease in movement of the face at points C and Im. No significant change was seen for points Ls and A. Group B was noted to have a statistically significant increase in movement of the face at point A, C, and Im. Point Ls was also found to increase, however not significantly. CONCLUSION: Surgical repositioning of the maxilla anteriorly and/or inferiorly lengthens the facial musculature resulting in an increase in facial movement while smiling. Likewise surgically repositioning the maxilla superiorly and/or posteriorly reduces the length of the facial musculature, resulting in a decrease in facial movement while smiling.

Adolescent↗
PubMed1997

Metronidazole resistance reduces efficacy of triple therapy and leads to secondary clarithromycin resistance.

There has been a significant increase in the prevalence of H. pylori resistance to metronidazole in recent years, while clarithromycin resistance is still relatively rare. In this study we assessed: (1) the effect of primary H. pylori resistance to metronidazole and clarithromycin on the clinical efficacy of a one-week regimen consisting of omeprazole, metronidazole, and clarithromycin; and (2) the rate of acquisition of secondary antimicrobial resistance after treatment failure. Eighty-seven patients with duodenal ulceration or nonulcer dyspepsia were included in the study. The primary metronidazole and clarithromycin resistance rates were 35.6% and 3.4%, respectively (all three pretreatment clarithromycin resistant strains had concurrent metronidazole resistance). H. pylori was eradicated in 81.6% of patients. The eradication rate for fully sensitive isolates was 98.2% (55/56) but was significantly reduced to 57.1% (16/28) for isolates that were resistant to metronidazole alone and 0% (0/3) in cases of dual resistance (P < 0.001). Secondary resistance to clarithromycin was acquired in 58.3% of cases of treatment failure. In areas of high prevalence of primary metronidazole resistance, this is a significant cause of treatment failure with this triple therapy regimen. This leads to the selection of strains with dual resistance that are difficult to eradicate and may contribute to an increase in the prevalence of clarithromycin resistance. In such areas an alternative first-line treatment should be prescribed.

Adult↗
PubMed1997

Impairment of visual object-discrimination learning after perirhinal cortex ablation.

Eight cynomolgus monkeys learned preoperatively 20 concurrent visual discriminations between pairs of colored shapes presented on a touch screen with 24-hr intertrial intervals. Three then received bilateral perirhinal cortex ablation, and 5 remained controls. The ablated monkeys were severely impaired in reacquiring the preoperatively acquired set, whereas postoperative learning of 20 new discriminations was not significantly affected. The task was then made more difficult. First, the number of foils from which the stimulus had to be selected was increased to 2, 4, 7, and then 14. Second, larger sets of 40, 80, and 160 problems were presented. Both manipulations revealed some significant but relatively mild impairments in the monkeys with ablations. It is suggested that perirhinal cortex ablation impairs the monkey's capacity to identify individual objects, which leads to deficits in both visual-object recognition memory and discrimination learning.

Animals↗
PubMed1997

Functional double dissociation between two inferior temporal cortical areas: perirhinal cortex versus middle temporal gyrus.

There is both anatomic and cytoarchitectural evidence for dorsal-ventral subdivisions of the inferior temporal cortex. Despite this, there has been only limited evidence of corresponding functional subdivisions and no evidence that two adjacent cortical areas within the inferior temporal cortex, namely area TE and the perirhinal cortex, have distinctly different roles in vision and memory. We assessed the color discrimination abilities of cynomolgus monkeys with either bilateral ablation of the perirhinal cortex or bilateral ablation of the middle temporal gyrus. The stimuli were isoluminant colored squares presented on a touch screen. In each trial the subject had to learn to discriminate and select the correct choice (green) from among a maximum of eight other foils, each varying in either hue or saturation. Relative to unoperated controls, monkeys with middle temporal gyrus lesions were severely impaired in the color discrimination task, whereas monkeys with perirhinal lesions were unimpaired on this task. We also assessed the visual recognition abilities, as measured by a basic delayed nonmatching-to-sample task with trial-unique objects presented in a Wisconsin General Test Apparatus, of rhesus monkeys with bilateral middle temporal gyrus lesions. We then tested the monkeys' postoperative performance on a delayed nonmatching-to-sample task with delays and extended list lengths. The results from this experiment were compared with those from two other groups of rhesus monkeys, an unoperated control group and a group with bilateral perirhinal cortex lesions, both of which had performed the identical tasks in a previous experiment. Relative to unoperated controls, monkeys with perirhinal cortex lesions were severely impaired both in relearning the basic delayed nonmatching-to-sample task and on the postoperative performance test. In contrast, monkeys with middle temporal gyrus lesions were only mildly affected in relearning the basic nonmatching task and were unimpaired on the postoperative performance test. Thus our data demonstrate a clear functional double dissociation between the perirhinal cortex and the middle temporal gyrus. This result gives strong support to the hypothesis that the perirhinal cortex and the adjacent area TE have distinctly different roles in visual learning and memory.

Analysis of Variance↗
PubMed1997

Eradication of Helicobacter pylori affects symptoms in non-ulcer dyspepsia.

BACKGROUND: The relationship between Helicobacter pylori infection and non-ulcer dyspepsia is controversial. METHODS: In a prospective, long-term, double-blind study we randomized 100 patients with non-ulcer dyspepsia and H. pylori infection to receive either of two treatment regimens: 1) bismuth-based triple therapy (n = 50) or 2) bismuth + placebo (n = 50). RESULTS: Triple therapy: subjects who became H. pylori-negative (n = 42) showed a significant symptomatic response when interviewed at 8 weeks, 6 months, and 1 year (P < 0.01). This improvement was evident in the 'ulcer-like' dyspepsia group at all times (P < 0.01) but in the 'reflux-like' and 'motility-like' groups at 6 months only (P < 0.01). Those who remained H. pylori-positive showed no decrease in symptoms at 8 weeks, 6 months, and 1 year. Bismuth-placebo therapy: subjects who became H. pylori-negative (n = 7) showed an improvement in symptoms at 8 weeks, 6 months, and 1 year. Those who continued to harbour the infection after treatment (n = 42) showed an insignificant improvement in the motility and non-specific groups only. CONCLUSION: This study shows that eradication of H. pylori results in a significant long-term reduction in symptoms of non-ulcer dyspepsia.

Adult↗
PubMed1997

A validated dyspepsia symptom score.

BACKGROUND: The primary endpoint in clinical trials involving patients with non-ulcer dyspepsia is subjective, i.e., reduction in symptomatology. Three attributes, reproducibility, responsiveness and validity, are necessary for the use of a symptom scoring system in a clinical trial. METHODS: The four most common symptoms in 50 dyspeptic patients were determined. To check the reproducibility of the symptom score, 48 patients and thirty control subjects were interviewed on two occasions (T0, T1), prior to any diagnostic or therapeutic intervention. Responsiveness was assessed by comparing the symptom scores of patients before (T0) and after (T2) treatment. Validity was assessed by comparing the symptom scores of dyspeptic patients to those of healthy volunteer subjects. RESULTS: Reproducibility The median T0 (16.00 and 6.90) and T1 (15.00 and 6.56) scores of the patients and controls did not significantly vary during the one-week interval. Responsiveness The symptom scores at T0 had decreased at T2 for patients with gastro-oesophageal reflux (17.00 to 11.50, p = 0.0014), non-ulcer dyspepsia where Helicobacter pylori was eradicated (16.00 to 7.00 p = 0.0014), and duodenal ulceration (18.50 to 7.50, p = 0.0117) while there was an insignificant decrease (18.00 to 13.00, p = 0.0642) in non-ulcer dyspepsia patients who received a prokinetic agent. Validity The mean rank symptom score of 74 patients (71.74) was significantly higher than that of the control population (26.83), (p = 0.0001). The mean time taken to perform the questionnaire was 3.6 minutes. CONCLUSION: This questionnaire is suitable for the assessment of symptoms in patients with dyspepsia.

Adult↗
PubMed1996

Efficacy and safety of procainamide in preventing arrhythmias after coronary artery bypass surgery.

Arrhythmias are common after cardiac surgery and are associated with hemodynamic compromise, stroke, and prolonged hospitalization. Beta blockers prevent atrial fibrillation postoperatively, but there are few data regarding the prophylactic use of type 1 antiarrhythmic agents or the prevention of ventricular arrhythmias. Accordingly, we performed a randomized, double-blind, placebo-controlled study of the effects of oral procainamide on 100 patients undergoing elective coronary artery bypass surgery. Procainamide was received for 4 days; the dosage was adjusted for body weight. Patients receiving procainamide had a significant reduction in atrial fibrillation (16 vs 29 patient-days, p < 0.05) and ventricular tachycardia (2% vs 20%, p < 0.01). However, the incidence of atrial fibrillation was not significantly reduced (38% vas 26%). In the group achieving therapeutic serum procainamide levels, there was reduction in all measured postoperative arrhythmias. No serious cardiac or noncardiac adverse events were noted during procainamide therapy, although there was a significant increase in the incidence of nausea. We conclude that procainamide reduces arrhythmias in the early postoperative period after coronary artery bypass surgery, most prominently in patients who achieve therapeutic serum levels. This was associated with no serious cardiac adverse reactions.

Administration, Oral↗
PubMed1996

Composite aortic root replacement with direct coronary artery implantation.

BACKGROUND: Composite aortic root replacement is accepted treatment for aneurysms of the ascending aorta involving the root with aortic valve regurgitation, but controversy continues regarding the best technique of operation. We excise the aneurysm, implant a composite valve graft, directly attach the coronary arteries to the aortic graft, and make the distal anastomosis to the divided aorta. METHODS: We reviewed the records and collected complete follow-up data on 110 consecutive patients having composite aortic root replacement with this technique from 1979 to 1995. RESULTS: Average age was 54 years. Marfan's syndrome was present in 22 patients, acute dissections in 26, chronic dissections in 11, and active endocarditis in 13. Operative characteristics were: 25 emergency procedures, 33 urgent procedures, 52 elective procedures, 24 reoperations, and 19 with coronary artery bypass grafting. Hospital death occurred in 8 patients (7.3%). Multivariate predictors of hospital death were postoperative renal failure and acute dissection. Actuarial survival was 70% at 10 years (standard error, 5%). Multivariate predictors of total mortality were porcine valve, Björk-Shiley valve, preoperative stroke, reoperation on a composite valve graft, and coronary artery bypass grafting. Only 3 patients required late reoperation, all for valve dysfunction. Actuarial freedom from reoperation on the aortic root was 97.3% (standard error, 1.9%) at 10 years. Late echocardiograms in 47 patients showed no anastomotic aneurysms. CONCLUSIONS: Composite aortic root replacement with direct coronary implantation is effective and durable treatment for a variety of aortic pathologic conditions in elective and emergency situations.

Actuarial Analysis↗
PubMed1996

The safety and efficacy of ranitidine bismuth citrate in combination with antibiotics for the eradication of Helicobacter pylori.

BACKGROUND: Ranitidine bismuth citrate is a novel salt of ranitidine and a bismuth citrate complex. It has intrinsic antisecretory and anti-Helicobacter pylori activity, but monotherapy rarely eradicates H. pylori infection in man. AIM: A pilot study to investigate rates of H. pylori eradication achieved by co-prescription of ranitidine bismuth citrate with antibiotics, and to identify several regimens which would merit further investigation. METHOD: One hundred dyspeptic patients infected with H. pylori were randomly allocated to treatment with ranitidine bismuth citrate 800 mg b.d. plus either amoxycillin, metronidazole, clarithromycin, cefuroxime axetil, tetracycline, tetracycline plus metronidazole or clarithromycin plus tetracycline for 14 days. Eradication of infection was assessed using the 13C-urea breath test 4 weeks after the end of treatment. RESULTS: In a per protocol analysis eradication of H. pylori ranged between 22 and 100%; the intention-to-treat eradication rates ranged between 15 and 92%. No adverse events were specifically attributed to ranitidine bismuth citrate. CONCLUSION: Co-prescription therapy, using ranitidine bismuth citrate and one or more antibiotics, is suitable for further investigation in large-scale clinical trials in patients infected with H. pylori.

Adult↗
PubMed1996

The effects of guided tissue regeneration and fixation technique on osseous wound healing in rabbit zygomatic arch osteotomies.

The development of fibrous nonunions after craniofacial surgery is thought to result from an interaction of biomechanical stress and the differential migration of various tissue types into the wound site during healing. The present study is designed to test this hypothesis through the manipulation of guided tissue regeneration and osteotomy fixation techniques in an experimental rabbit model. Bilateral, critical size (5 mm), vertical osteotomies (n = 32) were produced in the zygomatic arches of eight adult rabbits. The mobile bony segments were fixed rigidly or nonrigidly using bone microplates and screws or osteosynthetic wires. The defects were then covered with a resorbable collagen membrane or left uncovered. The rabbits were followed for 4 weeks with serial dorsoventral cephalographs and the zygomatic arches harvested for histological analysis. Cephalometric results revealed significantly (p < 0.001) increased bone growth in the margins of the defects covered with the collagen membrane; however, no significant (p > 0.05) differences were noted between fixation techniques. Histological analysis revealed that defects fixed rigidly and covered by the membrane showed the most rapid and organized osseous wound healing, followed by the defects that were fixed nonrigidly and membrane covered. The defects not covered by the collagen membrane showed invasion by fibroblasts resulting in fibrous nonunions. These results demonstrate the efficacy of guided tissue regeneration with a resorbable collagen membrane in preventing fibrous tissue ingrowth in large bony defects. The addition of rigid fixation at a potentially mobile site appeared to enhance bony trabecular organization but not the osteogenic rate in this rabbit model.

Animals↗
PubMed1995

Neurosensory recovery following the mandibular bilateral sagittal split osteotomy.

PURPOSE: This prospective study evaluated the neurosensory recovery pattern of the inferior alveolar nerve following the bilateral sagittal split osteotomy (BSSO). PATIENTS AND METHODS: Forty-two consecutive patients undergoing BSSO were studied using five neurosensory tests: 1) static light touch, 2) moving touch discrimination, 3) two-point discrimination, 4) nociception, and 5) thermoreception. Intraoperative assessment of inferior alveolar nerve damage was made; other variables recorded included type of fixation, age, concomitant procedures, advancement vs setback, and magnitude of the movement. A subjective questionnaire was completed by the patient. RESULTS: The variables that affected neurosensory function following BSSO were degree of nerve damage and the amount of time elapsed following surgery. Larger myelinated fibers (A-alpha) recovered slower and to a lesser degree at all time intervals up to 2 years when compared with small myelinated and unmyelinated nerve fibers. The magnitude of nerve damage directly correlated with early neurosensory deficit, but equalized over time. CONCLUSION: The long term (6 months and greater) chance for neurosensory recovery is good despite intraoperative nerve manipulation. Patients seem to adapt and report normal neurosensory function even though objective testing indicates continued neurosensory deficit.

Adolescent↗
PubMed1995

Intrusion anchorage potential of teeth versus rigid endosseous implants: a clinical and radiographic evaluation.

The purpose of this study was to compare the intrusion anchorage potential of teeth to osseointegrated titanium implants. Titanium implants were surgically placed unilaterally in a healed mandibular fourth premolar extraction site in eight adult mongrel dogs. The implants were surgically uncovered 3 months later and second stage abutments with soldered edgewise brackets secured. Edgewise brackets were also placed on the ipsilateral third premolars and on the contralateral third and fourth premolars. Segmental edgewise arch wires were placed between the implant and the third premolar and between the contralateral third and fourth premolars. Intrusion arch wire bends (v-bends) just mesial to the implant and the fourth premolar brackets were adjusted to apply a 50 to 60 gm intrusive force to the third premolars, bilaterally. Seven weeks later this force was increased to approximately 100 gm. Force levels were monitored biweekly for a total period of 16 weeks. Superimposition of initial and final periapical radiographs with bone markers demonstrated that for each dog the implant remained immobile and the third premolar on the implant anchor side was intruded in a curved path. On the contralateral side of the arch the dental anchor (fourth premolar) underwent an adverse reactive tip-back movement, and the third premolar was not intruded. We conclude that rigid endosseous implants are superior to dental anchorage for orthodontic intrusion of teeth and offer a potential means to intrude anterior teeth in adult patients with missing posterior teeth.

Animals↗
PubMed1994

Mitral valve reconstruction versus replacement for degenerative or ischemic mitral regurgitation.

Between January 1985 and June 1992, 263 consecutive patients had mitral valve reconstruction (133 patients) or replacement (130 patients) for degenerative or ischemic mitral regurgitation. The two groups were similar in sex, age, prior infarctions or cardiac operations, hypertension, angina, and functional class. Both groups were similar in mean ejection fraction, pulmonary artery pressure, cardiac index, and incidence of coronary artery disease. More reconstruction than replacement patients had ischemic etiology (22 [16%] versus 12 [9%]; p = not significant), and fewer reconstruction patients had ruptured anterior leaflet chordae (9 [7%] versus 39 [30%]; p < 0.01). More reconstruction than replacement patients had concomitant cardiac procedures (67 [50%] versus 59 [45%]; p = not significant). Hospital death occurred in 4 reconstruction patients (3%) and 15 (12%) replacement patients (p < 0.01). Median postoperative stay was shorter in reconstruction patients (10 versus 12 days; p = 0.02). Late valve-related death occurred in 3 reconstruction patients (2%) and 8 (6%) replacement patients (p = 0.08). Six-year actuarial freedom from thromboembolism was 92% for the reconstruction group and 85% for the replacement group (p = 0.12). Freedom from all valve-related morbidity and mortality was 85% for the reconstruction patients and 73% for the replacement patients (p = 0.03). Significant multivariate predictors of hospital death were age, mitral valve replacement, functional class, congestive heart failure, no posterior chordal rupture, and nonelective operation. Mitral valve reconstruction, when technically feasible, is the procedure of choice for degenerative or ischemic mitral regurgitation because of significantly lower hospital mortality and late valve-related events.

Actuarial Analysis↗
PubMed1994

Reoperative coronary grafting: changing patient profiles, operative indications, techniques, and results.

To assess the changing trends in patient profiles, operative indications and techniques, and their impact on the results of reoperative myocardial revascularization, we reviewed the records of 750 consecutive patients who had an isolated first reoperation for coronary artery disease at the Massachusetts General Hospital from 1977 to 1992. The patients were chronologically grouped into three equal cohorts of 250 patients. Our assessment over time revealed a significantly (p < 0.03) increased incidence of the following: older age, peripheral vascular disease, grafts at the first revascularization, longer operative interval, interval infarctions and angioplasties, and congestive heart failure and unstable angina requiring greater use of preoperative intraaortic balloon pumping. At catheterization significantly more left main coronary disease, lower ejection fractions, and more patent but diseased grafts were found. The reoperations were significantly done more urgently, with more grafts placed and a greater use of mammary artery grafting. Despite these increased risks over time, median postoperative hospital stay was significantly shortened (p < 0.001), though hospital mortality (5.3%) and perioperative myocardial infarction (6.3%) did not change significantly. Significant multivariate predictors of hospital death were nonelective operation, perioperative myocardial infarction, prior myocardial infarction, and mammary artery grafting at the initial operation.

Adult↗
PubMed1994

(S)-3-methyl-5-(1-methyl-2-pyrrolidinyl)isoxazole (ABT 418): a novel cholinergic ligand with cognition-enhancing and anxiolytic activities: II. In vivo characterization.

(S)-3-methyl-5-(1-methyl-2-pyrrolidinyl)isoxazole (ABT 418), an isoxazole analog of (-)-nicotine, is a potent agonist at the alpha-4/beta-2 subtype of neuronal nicotinic acetylcholine receptor (nAChR) that exists in mammalian brain (Arneric et al., 1994). Compared to (-)-nicotine, ABT 418 has reduced potency to interact with the subunit isoforms of nAChR found in sympathetic ganglia, and it does not compete for alpha-bungarotoxin binding sites in brain or at the neuromuscular junction. ABT 418 [minimum effective dose (MED), 0.062 mumol/kg i.p.) was 10-fold more potent in improving retention of avoidance learning in normal mice than (-)-nicotine, whereas the (R)-enantiomer of ABT 418, A-81754, was inactive. The memory-enhancing effect of ABT 418 was prevented by the nAChR channel blocker, mecamylamine. In the elevated plus-maze model of anxiety, ABT 418 (MED, 0.19 mumol/kg i.p.) increased open-arm exploration in mice, as previously shown for (-)-nicotine (MED, 0.62 mumol/kg i.p.). A-81754, did not have anxiolytic-like effects in this test. Unlike the classical anxiolytic, diazepam, ABT 418 did not impair rotorod performance in the dose range where beneficial effects occurred. In rats, ABT 418 (MED, 0.002 mumol/kg i.v.) was remarkably potent in enhancing basal forebrain-elicited increases in cortical cerebral blood flow, whereas resting cerebral blood flow was unaffected. Free running cortical electroencephalography in rats was unaffected by ABT 418 at a dose of 1.9 mumol/kg i.p., whereas the same dose of (-)-nicotine caused cortical activation (decreased power in the 1-13 Hz range and increased power in the 25-50 Hz range). Whereas ABT 418 was approximately 3- to 10-fold more potent than (-)-nicotine in memory enhancement and anxiolytic test paradigms, the compound had less emetic liability in dogs as compared to (-)-nicotine, and was less potent than (-)-nicotine in eliciting hypothermia, seizures, death and reduction of locomotor activity in mice. The measured pharmacokinetic or brain disposition properties of ABT 418 in rats did not account for the observed enhancement in efficacy with reduced toxicity as compared to (-)-nicotine. The potent cognitive-enhancing and anxiolytic properties obtained for ABT 418 in animal models without eliciting significant side effects suggest that this ligand is a selective activator of cholinergic channel-mediated behaviors. Thus, ABT 418 may represent a novel, safe and effective treatment of the cognitive and emotional dysfunctions associated with Alzheimer's disease.

Alzheimer Disease↗
PubMed1994

Anxiolytic-like effects of the novel cholinergic channel activator ABT-418.

The hydrochloride salt of (S)-3-methyl-5-(1-methyl-2-pyrrolidinyl) isoxazole (ABT-418), a potent activator of select subtypes of neuronal nicotinic acetylcholine receptors enhanced retention in memory tests and induced anxiolytic-like effects in mice in the elevated plus maze. In the present studies in rats, ABT-418 induced a significant increase in the time spent by the rats in the open arms of the elevated plus maze (0.62 mumol/kg i.p.); the effect persisted up to 60 min after the injection and was blocked by mecamylamine (15 mumol/kg), a centrally acting nicotinic acetylcholine receptor channel blocker. ABT-418 was 6-fold and 1.6-fold more potent than diazepam and ondansetron, respectively. The anxiolytic-like effect of ABT-418 was observed after oral administration in rats (10-30 mumol/kg) and at slightly higher doses in 20-month-old rats (1.9 mumol/kg i.p.). Major metabolites of ABT-418 [(S)-1-methyl-5-(3-methyl-5-isoxazolyl)-2-pyrrolidinone, cis-ABT-418 N-oxide and trans-ABT-418 N-oxide] were inactive in the plus maze in mice up to 6.2 mumol/kg, did not affect body temperature and had minimal effects on locomotion. Like (-)-nicotine, ABT-418 was effective (4 and 13 mumol kg-1 day-1) to induce anxiolytic-like effects after a 14-day treatment through minipumps implanted subcutaneously. Acute administration of ABT-418 (0.62 mumol/kg i.p.) also attenuated the anxiogenic-like effect elicited by withdrawal from chronic (-)-nicotine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗