Biomedical subjects
Publications and source records attributed to M J Sullivan.
This article reviews the major regional myocutaneous flaps available for soft-tissue coverage in the head and neck region. Specific flaps discussed include the pectoralis myocutaneous, latissimus dorsi myocutaneous, trapezius myocutaneous, sternocleidomastoid muscle, and temporalis muscle flaps.
Microvascular free flaps have revolutionized the reconstruction of soft-tissue defects in the head and neck region in the last decade. In this article, the anatomy, surgical techniques, advantages, and disadvantages of a variety of flaps are discussed.
Lipoprotein(a) [Lp(a)] is a distinct lipoprotein of the low density lipoprotein (LDL) class. Research has shown that elevated Lp(a) is an independent risk factor for coronary heart disease (CHD). The purpose of this cross-sectional study was to determine whether fitness was associated with Lp(a) concentrations. Cardiorespiratory (CR) fitness, assessed by maximal treadmill time, percent body fat (hydrodensitometry), body fat distribution (waist/hip ratio), lipoprotein profile and LDL particle size (2-16% gel electrophoresis) were determined in healthy Caucasian men (N = 100) and women (N = 50). As expected, the frequency distribution of Lp(a) was highly skewed with a mean level of 16.9 +/- 19.1 mg.dl-1 (range 0.10-90 mg.dl-1) for men and women combined. Lp(a) was only significantly (P < 0.05) correlated with cholesterol (r = 0.29) in women and LDL-C (r = 0.22) in men. However, after correcting LDL-C for Lp(a) content, the correlation was not significant (r = 0.06). A MANCOVA, controlling for age, across highest and lowest CR fitness quartiles suggest a typical positive influence of improved CR fitness on lipoproteins, body composition, and fat distribution; however, Lp(a) levels were not affected. These data indicate that there is no direct association between plasma Lp(a) and body composition, fat distribution, or CR fitness in healthy men and women.
BACKGROUND: Tissue expansion is a concept based on the skin's natural ability to stretch in response to an underlying force. OBJECTIVE: The purpose of this article is to review the histological and physiological changes that occur within the soft tissue and underlying structures during tissue expansion. METHODS: An extensive search of the literature reviewing these changes is summarized herein. RESULTS: Conventional tissue expansion may result in epidermal hypertrophy, decreased dermal, muscle, and adipose thickness, and bone resorption. A vascular capsule and angiogenesis provides a highly vascular flap and improves flap viability. Few soft tissue changes occur during rapid tissue expansion. The ability of the skin to increase in surface area during conventional tissue expansion is primarily because of biological tissue creep. Rapid expansion may result from mechanical tissue creep. CONCLUSION: Many soft tissue changes occur during tissue expansion. Most of these changes return to the pre-expansion state over time following discontinuation of the expansion process.
Our preferred technique for mandibular reconstruction uses a revascularized osseomyocutaneous flap. However, to reconstruct small lateral defects in dentulous patients, the AO mandibular reconstruction plate (MRP) is used. Its advantages include quick, reliable placement without a donor site or the need for advanced technical training. This review examines 16 patients who underwent primary mandibular reconstruction after ablative oncologic surgery using an AO MRP without a bone graft. The average follow-up was 32 months. Twelve patients (75%) had successful reconstructions, while 4 (25%) developed serious complications resulting in failure of the MRP. The most significant factor limiting rehabilitation was disease progression, affecting 12 (75%) of the 16 patients. In this subgroup of selected patients with small (< 6 cm) lateral mandibular defects, useful dentition, and advanced disease, or whose general medical condition precludes prolonged general anesthesia, primary mandibular reconstruction using an AO MRP and a myocutaneous flap without a bone graft is a viable reconstructive alternative.
AIM: To evaluate ondansetron as the sole antiemetic in children treated with emetogenic chemotherapy and irradiation. METHODS: Fifteen children aged 3-11 years were studied. Seven had acute lymphoblastic leukaemia, two acute myeloid leukaemia, two lymphoma and four had other tumours. Ondansetron 5 mg/m2 IV or 4 mg by mouth was given immediately before chemotherapy or radiation treatment and continued eight hourly for 24 hours. Nausea and vomiting was assessed during treatment and for the next 48 hours, and graded using WHO criteria. RESULTS: Thirty-eight courses of chemotherapy were assessed, 27 severely emetogenic and 11 moderately emetogenic. Two included total body irradiation. The most severe nausea and vomiting was grade 2 (transient vomiting) reported in six children. Nausea and vomiting was abolished on subsequent courses in four of these children by increasing the ondansetron dose frequency to six hourly. The remaining children experienced no nausea or vomiting (n = 7) or only nausea (n = 2). Nausea and vomiting were each completely controlled in 27 courses. CONCLUSIONS: Ondansetron is a cost effective and safe antiemetic in children receiving chemotherapy and total body irradiation, minimises weight loss on treatment and enables outpatient chemotherapy in some cases.
Aminopeptidase inhibitors have been demonstrated to enhance the behavioral effects of both exogenously applied and endogenously released neuropeptides. In this study peptidase inhibitors were used as probes for involvement of central neuropeptides in osmotically-induced drinking behavior. Intracerebroventricular (i.c.v.) injections of amastatin, an aminopeptidase A inhibitor, potentiated water intake induced by subcutaneous injections of hypertonic saline. Drinking responses to i.c.v. infusions of hypertonic saline were also enhanced when amastatin was added to the infusions. The effect was not attenuated by the angiotensin receptor antagonist, [Sar1, Thr8]angiotensin II, which suggests that angiotensins do not play a role in the over-drinking. Drinking responses to centrally infused hypertonic saline were not enhanced by i.c.v. thiorphan, an endopeptidase inhibitor; this provides evidence that the effects of amastatin are specific for a particular class of peptidases. These results suggest that there is a role for an endogenous, non-angiotensinergic brain peptide in the mediation of osmotic thirst.
The lateral arm fasciocutaneous free flap is a versatile donor site of sensate soft tissue for reconstruction and augmentation of the head and neck. The lateral arm flap can be quickly harvested without interference to the head and neck team and with minimal morbidity to the patient. For these reasons, this flap has become our soft-tissue flap of choice.
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Although the pathophysiology of exercise intolerance in patients with chronic heart failure (CHF) is not fully understood, it appears that the cardiac output response plays an important role in limiting exercise in this disorder. Although previous studies have demonstrated that peak VO2 is not related to left ventricular (LV) ejection fraction, studies have consistently identified peak exercise cardiac output as an important predictor of peak VO2. It is likely that a reduced cardiac output to work rate relationship in CHF causes hypoperfusion of both working skeletal muscle and visceral organs, which leads to early anaerobic metabolism and fatigue. Several factors may influence the cardiac output response in patients with severe systolic LV dysfunction, including heart rate, diastolic LV function, and the mitral regurgitation fraction. Although stroke volume increases through use of the Frank-Starling mechanism in many patients with severe systolic LV dysfunction, some patients with this disorder may not increase stroke volume during exercise due to diastolic LV dysfunction or pericardial constraint. The finding that this latter group has more severe exercise intolerance suggests that diastolic dysfunction may further decrease peak VO2 in this disorder. Variations in the mitral regurgitation fraction also have been found to have an important effect on exercise stroke volume in some patients with CHF. Therefore, the finding that LV ejection fraction at rest or during exercise is not related to peak VO2 in patients with systolic LV dysfunction does not necessarily indicate that central hemodynamics do not play a role in exercise intolerance. Rather, it is likely that variability in the LV ejection fraction with exercise, which does not take variable increases in LV end-diastolic volume or mitral regurgitation into account, plays only a modest role in determining the stroke volume and cardiac output response to exercise in patients with severe systolic dysfunction.
Adult male Sprague-Dawley rats were injected with either ibotenic acid (5 micrograms/1 microliter) or vehicle in the ventral median preoptic nucleus. The injections were given during either methoxyflurane or ketamine anesthesia. None of the rats injected with ibotenic acid were adipsic after surgery. After at least one week of recovery, all rats were tested for drinking responses to angiotensin II (1.5 and 3 mg/kg s.c.) and hypertonic saline (3% and 12% 1 ml/100 g b.wt.). Rats injected with ibotenic acid during methoxyflurane anesthesia drank significantly less than the vehicle injected control group in tests with both doses of angiotensin II and both concentrations of hypertonic saline. The rats that were injected with ibotenic acid during ketamine anesthesia drank significantly less than the control group when tested with 3% hypertonic saline but not when tested with angiotensin II. Histological examination of the injection sites indicated significant reductions in the volume of the median preoptic nucleus only in rats that had been injected with ibotenic acid during methoxyflurane anesthesia. The results are consistent with the interpretation that the drinking response to angiotensin II is dependent upon the integrity of neurons with postsynaptic N-methyl-D-aspartate receptors within the median preoptic nucleus.
To define the effects of gender on stroke volume control during upright exercise in normal subjects, we examined central hemodynamics in 34 men and 27 women during staged bicycle ergometry. Central hemodynamics were assessed by right-sided cardiac catheterization and simultaneous radionuclide angiography. Left ventricular end-diastolic and end-systolic volumes were calculated from the stroke volume (by direct Fick) and the corresponding left ventricular ejection fraction. Men were larger than women (1.85 +/- 0.11 vs 1.65 +/- 0.13 m2, p less than 0.001) but groups were matched for age (39 +/- 12 vs 36 +/- 9 years, p = 0.27). Oxygen consumption at peak exercise was higher in men than in women (2.51 +/- 0.50 vs 1.74 +/- 0.30 liters/min, p less than 0.001) but was not different when adjusted for body weight (31.5 +/- 8.1 vs 28.4 +/- 6.4 ml/kg/min, p = 0.14), indicating similar levels of overall fitness in the 2 groups. At rest and during submaximal and maximal exercise, stroke volume and left ventricular end-diastolic and end-systolic volumes were higher in men than in women, but there were no intergroup differences in stroke volume index, left ventricular ejection fraction, and left ventricular end-diastolic or end-systolic volume indexes. Comparison of derived regression equations of cardiac index, stroke volume index and left ventricular end-diastolic and end-systolic volume indexes revealed no differences in the time course or magnitude of changes with respect to oxygen consumption, expressed as percentage of peak oxygen consumption, in the 2 groups.(ABSTRACT TRUNCATED AT 250 WORDS)
This study reports the physiologic effects of up to 14 months of aerobic exercise in 101 older (greater than 60 years) men and women. After an extensive baseline physiologic assessment (Time 1), in which aerobic capacity and blood lipids were measured, subjects were randomized to an aerobic exercise condition (cycle ergometry, 3 times per week for 1 hour), nonaerobic yoga (2 times per week for 1 hour), or a waiting list nonexercise control group for 4 months, and then underwent a second (Time 2) assessment. At the completion of the second assessment, all remaining subjects completed 4 months of aerobic exercise and were reevaluated (Time 3). Subjects were given the option of participating in 6 additional months of supervised aerobic exercise, and all available subjects completed a fourth assessment (Time 4) 14 months after their initial baseline evaluation. Results indicated that subjects generally exhibited a 10 to 15% improvement in peak oxygen consumption after 4 months of aerobic exercise training, and a 1 to 6% improvement in aerobic power with additional aerobic exercise training. On the other hand, subjects, especially men, continued to have improvements in submaximal exercise performance (i.e., anaerobic threshold). In addition, aerobic exercise was associated with an improved lipid profile; subjects participating in aerobic exercise for up to 14 months exhibited increased levels of high-density lipoprotein cholesterol. Maintenance of regular aerobic exercise for an extended time interval is associated with greater cardiovascular benefits among older adults than has been reported previously.
To our knowledge, a histologic evaluation of bone healing after mandible reconstruction with vascularized human bone grafts has not been previously reported. Serial sections through both the decalcified graft and the junction between mandible and graft were evaluated in four patients who required surgical removal of their reconstructed mandibles. A failed scapular bone graft that had been wrapped within a pectoralis major myocutaneous flap for salvage following pedicle thrombosis showed markedly resorbed but viable bone with a fibrous union to the native mandible. Viable vascularized grafts without evidence of ongoing resorption characterized an iliac osteocutaneous bone graft and two scapula osteocutaneous grafts that healed with continuity of healthy bone between graft and mandible. Observations from the evaluation of these specimens are made regarding bone circulation, bone union, and bone graft survival as they occur clinically. Implications regarding the techniques of bone plating and indications for use of vascularized bone in mandible reconstruction are discussed.
Lhermitte's sign is a rare complication of head and neck irradiation involving the delivery of dose to the cervical spinal cord. Although uncommon, symptoms of lightning-like electric sensations spreading into both arms, down the dorsal spine, and into both legs on neck flexion following head and neck irradiation, causes great concern in both the patient and the physician. This spontaneously reversible phenomenon is important for the otolaryngologist and radiation oncologist to recognize and discuss. A particularly severe and protracted case of Lhermitte's sign involving a patient recently completing a radical course of radiation for nasopharyngeal carcinoma is described in detail, including a review of the literature surrounding the cause and management of this condition.
Invasive cardiopulmonary exercise testing was performed in 7 patients who presented with congestive heart failure, normal left ventricular ejection fraction and no significant coronary or valvular heart disease and in 10 age-matched normal subjects. Compared with the normal subjects, patients demonstrates severe exercise intolerance with a 48% reduction in peak oxygen consumption (11.6 +/- 4.0 versus 22.7 +/- 6.1 ml/kg per min; p less than 0.001), primarily due to a 41% reduction in peak cardiac index (4.2 +/- 1.4 versus 7.1 +/- 1.1 liters/min per m2; p less than 0.001). In patients compared with normal subjects, peak left ventricular stroke volume index (34 +/- 9 versus 46 +/- 7 ml/min per m2; p less than 0.01) and end-diastolic volume index (56 +/- 14 versus 68 +/- 12 ml/min per m2; p less than 0.08) were reduced, whereas peak ejection fraction and end-systolic volume index were not different. In patients, the change in end-diastolic volume index during exercise correlated strongly with the change in stroke volume index (r = 0.97; p less than 0.0001) and cardiac index (r = 0.80; p less than 0.03). Pulmonary wedge pressure was markedly increased at peak exercise in patients compared with normal subjects (25.7 +/- 9.1 versus 7.1 +/- 4.4 mm Hg; p less than 0.0001). Patients demonstrated a shift of the left ventricular end-diastolic pressure-volume relation upward and to the left at rest. Increases in left ventricular filling pressure during exercise were not accompanied by increases in end-diastolic volume, indicating a limitation to left ventricular filling.(ABSTRACT TRUNCATED AT 250 WORDS)
Using 31P spectroscopy and magnetic resonance imaging (MRI), the authors studied changes in muscle phosphorous metabolites and T2 with isometric knee extension to evaluate the potential role of T2 images in coil placement for exercise spectroscopy studies. Increased signal intensity was visible in active muscles on T2 images after exercise. Calculated T2-weighted values were elevated immediately after exercise in the quadriceps (P less than .01). T2 increases for individual quadricep muscles varied, with the largest changes in the rectus femoris and the least in the vastus lateralis. 31P spectroscopy studies demonstrated similar findings: percent change in T2 correlated positively with inorganic phosphorus to phosphocreatine ratio (Pi/PCr) (r = 0.89, P less than .01) and negatively with pH (r = -0.88, P less than .01). The correlations between imaging and spectroscopy suggest that T2 images may allow more precise placement of phosphorous coils in exercise studies. The heterogeneity of T2 changes within the quadriceps with exercise suggests that assumptions about muscle activity may be misleading. T2 images may provide muscle activity verification for exercise studies.
A review of the first 52 consecutive coronary artery bypass surgery patients to receive oxygenated blood cardioplegia, with warm reperfusion cardioplegia ('hot shot'), was undertaken to evaluate its effectiveness in myocardial protection. The chosen parameters of ischaemia were: (i) the occurrence of ventricular fibrillation (VF) on release of the aortic cross-clamp (ACC); (ii) the occurrence of bradycardia due to cardiac conduction defects; (iii) the use of inotropes with or without the use of the intra-aortic balloon pump (IABP); (iv) evidence of myocardial infarction (MI) on the postoperative electrocardiograph (ECG); and (v) peri-operative cardiogenic mortality. Warm induction cardioplegia was cooled after cardiac standstill. Repeat cold cardioplegia was given as required at intervals and warm reperfusion cardioplegia was given prior to release of the ACC. Of the 52 patients studied none developed VF after release of the ACC; one patient with pre-operative complete heart block required temporary cardiac pacing; no patient required inotropes or IABP and there was no postoperative MI or mortality. The warm blood cardioplegia technique has not resulted in any detectable evidence of inadequate myocardial protection. A beneficial effect has been demonstrated by the absence of VF, cardiac conduction defects, myocardial failure, MI and mortality.