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Biomedical subjects

A DiBiase

Publications and source records attributed to A DiBiase.

8 recordsLinked to original sources
PubMed2003

Class III Twin Blocks: a case series.

OBJECTIVE: To evaluate the use of Class III Twin Blocks for the early treatment of Class III malocclusion. DESIGN: Retrospective analysis. SUBJECTS AND METHOD: 14 subjects were consecutively treated with a modified version of the Class III Twin Block appliance. Lateral cephalometric radiographs taken at the start and end of treatment were assessed digitally. RESULTS: The mean age of subjects was 10 years and mean treatment time was 6.6 months. The cephalometric analysis of changes during treatment shows proclination of the upper incisors [mean 5.1 degrees, SD 5.1], retroclination of the lower incisors [mean -4.5 degrees, SD 3.9], reduction in angle SNB [mean -1.3 degrees, SD 1.8] and an increase in the maxillary/ mandibular planes angle (mean 2.1 degrees, SD 2.2]. Average cephalometric digitizations and photographs of a clinical case are shown. CONCLUSIONS: Class III Twin Blocks can be used successfully for early treatment of Class III malocclusion. A randomly allocated prospective study is required to fully evaluate the efficacy of this appliance.

Cephalometry↗
PubMed1995

Malignant ameloblastoma revisited.

A case of a malignant ameloblastoma in a 49-year old Sri Lankan woman with widespread pulmonary metastases is presented, the diagnosis confirmed by needle biopsy. The current histological classification of odontogenic carcinomas and the management of metastatic pulmonary deposits are discussed.

Ameloblastoma↗
PubMed1991

Frequency and mechanism of bradycardia in cardiac transplant recipients and need for pacemakers.

Orthotopic cardiac transplantation is occasionally complicated by unexplained bradyarrhythmias. Sinus node injury as a consequence of operation or acute rejection has anecdotally been linked to the development of bradycardia early after transplantation. These arrhythmias are empirically managed by pacemaker implantation, the indications for which remain poorly defined. This retrospective study examined the 20-year experience of our institution with bradyarrhythmias after transplantation to determine the predisposing factors and indications for pacemaker implantation. Forty-one of 556 patients in our cardiac transplant program (7.4%) received permanent pacemakers between 1969 and 1989. The predominant rhythm disturbances were junctional rhythm (46%), sinus arrest (27%) and sinus bradycardia (17%). Most patients were asymptomatic (61%), and presented in the early post-transplant period (73%). Four possible predisposing factors were evaluated: (1) graft ischemic time, (2) rejection history, (3) use of bradycardia-inducing drugs, and (4) anatomy of blood supply to the sinoatrial (SA) node. No significant differences existed between patients with and without pacemakers with regard to the first 3 variables. However, after transplantation angiograms showed that prevalence of abnormal SA nodal arteries was greater in patients with than without pacemakers (p less than 0.02). Pacemaker follow-up at 3, 6 and 12 months showed persistent bradycardia (60 to 90 beats/min) in 88, 75 and 50% of patients, respectively. The most common pacemaker complication (15%) was lead displacement at time of biopsy. These results suggest that disruption of the SA nodal blood supply may be an important predisposing factor in the development of bradycardias.

Adolescent↗
PubMed1991

Freehand allograft aortic valve replacement and aortic root replacement. Utility of intraoperative echocardiography and Doppler color flow mapping.

UNLABELLED: Seventeen consecutive patients undergoing 20 planned aortic valve replacements with allograft valves at Stanford University Medical Center were studied with intraoperative epicardial echocardiography and Doppler color flow mapping before and after cardiopulmonary bypass. Native aortic valves were replaced in 12 of the 20 patients, and eight patients underwent second aortic valve procedures. In 17 of 20 patients allograft selection was guided by prebypass echocardiographic estimates of annular diameter and/or length of allograft aortic root required. Other prebypass findings included unanticipated severe mitral regurgitation in one patient (which precluded allograft aortic valve replacement), left-to-right shunts in five patients, ascending aortic dissection in one, and aortic root disease necessitating coronary reimplantation or bypass in two. Postbypass echocardiography demonstrated acceptable competency of 18 of 19 allograft valves (mild or no aortic insufficiency). Postbypass echocardiography also documented successful repair of four of five shunts and mild mitral regurgitation in 15 of 19 patients (versus 11 of 19 before bypass). CONCLUSIONS: Intraoperative echocardiography-Doppler mapping is a useful adjunct for allograft aortic valve or aortic root replacement; it allows confident selection of appropriate tissue size before aortic cross clamping, which minimizes delay from allograft thawing procedures. It also provides helpful information about the extent of aortic root disease and coronary ostial anatomy before bypass, confirms allograft competency after bypass, and detects accompanying valvular and other hemodynamic lesions before and after allograft valve replacement.

Adult↗
PubMed1990

Biochemical changes in central nervous system membranes in chronic-relapsing experimental allergic encephalomyelitis.

Biochemical studies of myelin fractions were undertaken on Lewis rats during various time-points in the development of chronic-relapsing experimental allergic encephalomyelitis (CR-EAE). Lipid and protein composition of myelin fractions obtained by sucrose density gradient centrifugation at 10, 19, 24, and 66 d postinduction (pi) were determined by high-performance thin-layer chromatography (HPTLC) and sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS PAGE), respectively. When comparing the myelin fractions of CR-EAE affected animals with those of controls, main differences were observed at 10 d pi. These changes were particularly evident in the light myelin fraction, where a decrease in the percentage of phosphatidylethanolamine and small basic protein relative to the total lipids and proteins of the fraction were observed. At 19 and 24 d pi no biochemical differences were present in both fractions. At 66 d pi, differences in the lipid composition were observed again only in the light myelin fraction. These findings suggest that the light myelin fraction is the most sensitive, particularly at the early stages of the disease, and must play a key role in demyelinating processes.

Animals↗
PubMed1990

Arrhythmias and clinical electrophysiology of the transplanted human heart.

The denervated transplanted heart has given us numerous opportunities to assess normal and abnormal electrophysiology and the influence of the autonomic system on these parameters. Observation of baseline electrophysiology of the denervated heart and its response to various physiologic and pharmacologic stimuli has emphasized the role of the parasympathetic system on heart rate and arrhythmia modulation in the normal population. In the transplant patients, the denervated hearts lack the full spectrum of physiologic responses due to the absence of vagally mediated neurostimuli. This results in a higher resting heart rate, sluggish rate response to exercise, and perhaps inadequate response to some commonly used drugs such as atropine and digitalis. Nevertheless, the heart's overall response to physiologic demands and various pharmacologic maneuvers including beta-antagonists and antagonists remains relatively normal and the patient's overall cardiac performance appears to be quite adequate. Thus, despite its shortcomings, the denervated heart provides near normal functional integrity and overall improved quality of life. Arrhythmias are generally a minor problem in these patients. Although there appears to be a high prevalence of various forms of arrhythmias, most present as isolated and insignificant problems. The more severe arrhythmias consist primarily of atrial tachyarrhythmias that are usually associated with acute rejection, and treatment for these arrhythmias never pose serious difficulty. However, sudden death remains an intriguing issue. Clearly, serious ventricular tachyarrhythmias can occur in these patients, arguing against the concept of a primary role of an intact autonomic nervous system for the generation of arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1977

On the nature and etiology of vascular ectasias of the colon. Degenerative lesions of aging.

Vascular lesions of the right colon are being diagnosed increasingly as a cause of lower intestinal bleeding, but their nature and occurrence, primarily in the elderly, remains unexplained. Colons from patients with clinical and angiographic diagnoses of cecal vascular lesions were studied by injection and clearing, and by histological sections. In all injected specimens one or more mucosal vascular ectasias were identified. The mucosal lesions appeared to be secondary to dilated tortuous submucosal veins which were the more prominent feature and were often present without the mucosal ectasia. This suggests that ectasias are caused by chronic, intermittent, low grade obstruction to submucosal veins with dilation and tortuosity initially of submucosal veins, then of venules, capillaries, and arteries of the mucosal vascular unit. Ultimately, precapillary sphincters lose their competency, producing small arteriovenous communications. The concept that ectasias are degenerative lesions was evaluated by studying 15 right colons resected for carcinoma with no history of bleeding. Mucosal ectasias were identified in four colons and submucosal ectasias in eight. These investigations suggested that these lesions: (1) are vascular ectasias developing as a degenerative process of aging, (2) are present with or without bleeding in a significant portion of the population over 60 years of age, (3) are multiple more often than single, and (4) may represent the commonest cause of major lower intestinal bleeding in the elderly.

Aged↗