Biomedical subjects
Publications and source records attributed to J M Henderson.
Several methods have been described in the literature for the management of acute auricular hematoma. Herein, we review the pathogenesis of auricular hematoma, describe the various treatment modalities, and report a case in which a thermoplastic splint was used to prevent recurrence of hematoma in a patient with immune thrombocytopenic purpura.
The surgical treatment of portal hypertension has laxed and waned over the past century. Decompressive shunts for variceal bleeding hit their peak in the 1970s, but dissatisfaction with encephalopathy and liver failure led to further developments with selective shunts and devascularization procedures in the 1970s and early 1980s. Liver transplant is the major operative intervention currently in use and of advantage to patients with portal hypertension. The role of the surgeon is as part of the team involved in the full evaluation of patients with cirrhosis and portal hypertension with its complications. The current repertoire of surgical options includes decompressive shunts, either total, partial or selective, devascularization procedures and liver transplantation. These options must be fitted into the overall management schema of pharmacologic and endoscopic therapy as the first-line approaches to managing these patients.
This study is designed to measure the impact of orthotopic liver transplantation (OLT) on patients' health-related quality of life. Two types of health-related quality-of-life questionnaires were administered at baseline and after OLT: generic (Medical Outcomes Study Short Form 36) and liver specific (Chronic Liver Disease Questionnaire). We also recorded clinical, demographic, and laboratory data. Pre-OLT scores of liver transplant candidates were compared with those of the general population and patients with congestive heart failure (CHF) and chronic obstructive pulmonary disease (COPD). Thirty-seven liver transplant candidates were evaluated: 25 men and 12 women; age, 50.2 +/- 12 years; Child's class A, 3 patients; class B, 30 patients; class C, 4 patients; and galactose elimination capacity, 277 +/- 81. Health-related quality-of-life scores for patients awaiting liver transplants were significantly lower than those for patients with COPD and CHF and those in the general population. Sex and cause of liver disease did not affect the scores. There was a weak but significant inverse correlation between some aspects of health-related quality of life and both age (r = -0.31 to -0.34) and worsening of the Child-Pugh score (r = -0.32 to -0.43). All measured aspects of health-related quality of life significantly improved after OLT, and mental health scores were indistinguishable from the population norms. Similar improvements were evident in physical and disease-specific aspects of health-related quality of life, but some residual dysfunction persisted.
BACKGROUND: In the 1990s, liver transplantations and transjugular intrahepatic portosystemic shunts (TIPS) have become the most common methods to decompress portal hypertension. This center has continued to use surgical shunts for variceal bleeding in good-risk patients who continue to bleed through endoscopic and pharmacologic treatment. This article reports this center's experience with surgical shunts and TIPS shunts from 1992 through 1999. METHODS: Sixty-three patients (Child A, 43 patients; Child B, 20 patients) received surgical shunts: distal splenorenal, 54 patients; splenocaval, 4 patients; coronary caval, 1 patient; and mesocaval, 4 patients. Sixty-two patients had refractory variceal bleeding, and 1 patient had ascites with Budd-Chiari syndrome. Two hundred patients (Child A, 24 patients; Child B, 62 patients; Child C, 114 patients) received TIPS shunts. One hundred forty-nine patients had refractory variceal bleeding, and 51 patients had ascites, hydrothorax, or hepatorenal syndrome. Data were collected by prospective databases, protocol follow-up, and phone contact. RESULTS: The 30-day mortality rate was 0% for surgical shunts and 26% for TIPS shunts; the overall survival rate was 86% (median follow-up, 36 months) for surgical shunts and 53% (median follow-up, 40 months) for TIPS shunts. For surgical shunts, the portal hypertensive rebleeding rate was 6.3%; the overall rebleeding rate was 14.3%. For TIPS shunts, the overall rebleeding rate was 25.5% (30-day, 9.4%; late, 22.4%). There were 4 reinterventions for surgical shunts (6.3%); the reintervention rate for TIPS shunts in the bleeding group was 33%, and the reintervention rate in the ascites group was 9.5%. Encephalopathy was severe in 3.1% of the shunt group and mild in 17.5%; this was not systematically evaluated in the TIPS shunts patients. CONCLUSIONS: Surgical shunts still have a role for patients whose condition was classified as Child A and B with refractory bleeding, who achieve excellent outcomes with low morbidity and mortality rates. TIPS shunts have been used in high-risk patients with significant early and late mortality rates and have been useful in the control of refractory bleeding and as a bridge to transplantation. The comparative role of TIPS shunts versus surgical shunt in patients whose condition was classified as Child A and B is under study in a randomized controlled trial.
Whilst many reports mention neurofibrillary tangle pathology in the thalamus in progressive supranuclear palsy, there has been little detailed regional analysis of the distribution and density of thalamic pathology in this disease or in other parkinsonian syndromes. The caudal intralaminar thalamic nuclei are the major thalamic regulators of the caudate nucleus and putamen, areas known to be dysfunctional in progressive supranuclear palsy and Parkinson's disease. We investigated whether these thalamic nuclei degenerate in patients with these disorders compared with age-matched, neurologically normal controls. Neurofibrillary tangle and Lewy body pathology was assessed and unbiased optical disector methods were used to quantify total neuronal number. Despite different thalamic pathology, there was a dramatic reduction in the total neuronal number in the caudal intralaminar nuclei in both progressive supranuclear palsy and Parkinson's disease (40-55% loss). In contrast, there was no loss of volume or total neuronal number in the limbic thalamic nuclei in either disease group, indicating selective degeneration of the caudal intralaminar nuclei. In Parkinson's disease, Lewy bodies were found in these regions, while in progressive supranuclear palsy abundant intracellular neurofibrillary tangles and glial tangles concentrated in the caudal intralaminar nuclei. However, tangle formation accounted for only a small proportion of cell loss (</=10%) in the thalamus in progressive supranuclear palsy. These findings have several implications. The caudal intralaminar thalamus appears to be one of three basal ganglia sites commonly affected in both progressive supranuclear palsy and Parkinson's disease. These sites are the dopaminergic substantia nigra, the cholinergic pedunculopontine tegmental nucleus and, from our results, the glutamatergic caudal intralaminar thalamus. In both diseases these sites contain characteristic but different pathologies, indicating disease-specific mechanisms of neurodegeneration. Interestingly, the proportion of remaining neurons affected by these pathologies is low. This may indicate additional (possibly common) cellular mechanisms responsible for the degeneration in these regions. Both the dopaminergic nigra and the glutamatergic caudal intralaminar thalamus are the major regulators of basal ganglia function via the caudate nucleus and putamen. The pedunculopontine tegmental nucleus has major projections to both of these regulators. These findings indicate that dysregulation of two neurotransmitter systems within the basal ganglia may underlie common parkinsonian symptoms in these disorders. For patients with Parkinson's disease, this loss of glutamate regulation may help explain some problems with dopamine replacement therapies, particularly over time. For patients with progressive supranuclear palsy, more widespread degeneration of basal ganglia structures would contribute to poor treatment outcomes.
Two major noncortical inputs to the striatum originate from the substantia nigra and the thalamic centré median-parafascicular complex. Although it is established that in Parkinson's disease there is degeneration of the nigral dopaminergic neurons, there has been little analysis of the glutamatergic centré median-parafascicular complex. We therefore evaluated these and neighboring thalamic nuclei (for specificity of any changes) in 9 Parkinson's disease patients and 8 age-matched controls. Degeneration in the substantia nigra and centré median-parafascicular complex was estimated by using quantitative neuronal counts. On average, 70% of the pigmented nigral neurons degenerated and there was 30% to 40% neuronal loss in the centré median-parafascicular complex in Parkinson's disease. Thalamic degeneration was marked in neuronal subpopulations (50% loss of parvalbumin-positive neurons in the parafascicular, and 70% loss of non-parvalbumin-positive neurons in the centré median nuclei). In contrast, adjacent thalamic nuclei did not degenerate, which supports a selective neurodegeneration of the centré median-parafascicular complex. Our results show that the thalamic centré median-parafascicular complex is an additional nondopaminergic site of neurodegeneration in Parkinson's disease. Because this thalamic region provides important sensorimotor feedback to the striatum, degeneration of this region is likely to exacerbate the clinical signs and symptoms of Parkinson's disease.
Experiments were carried out in swine to test the hypothesis that changes in the fluid dynamic environment of the arterial wall, with time constants of several minutes to perhaps a few hours, prompt adaptive responses that transiently increase endothelial permeability. After parenteral Evans Blue Dye (EBD) administration, the hemodynamics of the external iliac arteries of the experimental animals were altered using a reversible arteriovenous femoral shunt. For 3 h, the shunt was opened and closed with a period (tau) between 1-180 min. Subsequently, the animal was euthanized and the iliac vessels were photographed en face to obtain the distribution of EBD-bound albumin uptake by the tissue during its exposure to the dye. Albumin uptake increases with tau in a fashion that can be explained by an a priori model of the adaptive permeability response, with a time constant of about an hour.
Patients with end-stage liver disease (ESLD) may be at increased risk for syncopal episodes based on their circulatory physiological state. Although a definitive cause for this is not known, several mechanisms have been proposed. In patients with ESLD, defecation syncope may result from a failure of short-term neurocirculatory adaptation to the Valsalva maneuver in the face of a hyperdynamic circulatory state and a decreased effective intravascular volume. We describe 2 patients with ESLD who had repeated episodes of defecation syncope before orthotopic liver transplantation (OLT). The most effective treatment of these syncopal episodes appears to be fluid administration and the use of a pressor agent, such as dopamine, to help maintain both an effective heart rate and intravascular volume. Correction of this altered circulatory physiological state through OLT prevented further syncopal episodes in both patients. A search of the literature failed to show previous reports associating ESLD and defecation syncope. Possible mechanisms favoring this association are reviewed.
Two models of the interaction between scene meaning and object identification were tested: the description enhancement model and the criterion modulation model. The former proposes that the early activation of a scene schema facilitates the initial perceptual analysis of schema-consistent objects, the latter that schema activation modulates the amount of information necessary to indicate the presence of an object of a particular perceptual type. In Experiment 1, we employed a forced-choice, type-discrimination paradigm. Participants were asked to determine which of two semantically consistent objects or which of two semantically inconsistent objects had appeared in a briefly presented scene. Contrary to the prediction derived from both of these models, discrimination performance was better for semantically inconsistent versus consistent objects. In Experiments 2 and 3 we introduced a forced-choice, token-discrimination paradigm to further test the description enhancement model. Contrary to the prediction of that model, discrimination performance was no better for semantically consistent versus inconsistent tokens. These results suggest that both the initial perceptual analysis of an object and the matching of an object's constructed visual description to stored descriptions are isolated from stored knowledge about real-world contingencies between scenes and objects.
Ameloblastomas are benign tumors of odontogenic epithelial origin. There is a high incidence of local recurrence associated with these tumors, and distant metastasis is rare. A review of the English literature shows that there have been 41 prior reports of pulmonary metastases from ameloblastomas of the oral cavity. We present another case of ameloblastoma metastatic to the lung and review the histopathology and mechanism of metastatic spread.
Lesions of the subthalamic nucleus can restore some imbalances in motor output of the basal ganglia induced by nigrostriatal dopamine depletion, and have been proposed as a potential therapy for Parkinson's disease. Although there is substantial supporting evidence from experimental studies in both rats and primates, there is less information on the effects of subthalamic lesions alone. In order to characterize potential side effects, the present study evaluates the behavioural effects of unilateral excitotoxic lesions of the subthalamic nucleus in rats that have previously received either unilateral saline or 6-hydroxydopamine injections into the nigrostriatal bundle on the same side. The 6-hydroxydopamine lesions induced ipsilateral orientation asymmetries in head position and body axis bias, rotational asymmetries following injections of direct or indirect dopamine agonists, neglect of contralateral stimuli, and a reduction in the numbers of pellets retrieved with the contralateral paw in a skilled reaching task. Subsequent excitotoxic lesions of the subthalamic nucleus reduced (but did not abolish) rotational asymmetries, had no effects on the measures of neglect and skilled paw-reaching, and produced contralateral orientation biases in head turning and body axis curling. Rats that received subthalamic lesions alone exhibited de novo impairments comprising contralateral biases in the orientation tests. These results support a neuromodulatory role of the subthalamic nucleus in regulating motor outputs of the basal ganglia, and caution that there may be distinct side effects of the lesion by itself. Whereas some impairments attributable to dopamine depletion may be alleviated by subthalamic manipulations, other symptoms are not, or may even be aggravated.
OBJECTIVE: Hepatitis A can cause decompensation and death in patients with previous liver injury. The hepatitis A vaccine is recommended for patients with chronic liver disease. The aim of this study was to screen, immunize, and measure the safety and antibody response of the hepatitis A vaccine in liver failure and liver transplant patients. METHODS: This was a prospective immunization trial at a referral center for liver disease and liver transplantation. A total of 193 patients with severe chronic liver disease were screened and 24 patients were vaccinated. Sixteen end stage liver disease patients were compared with eight liver transplant patients. Hepatitis A vaccinations using 1440 ELISA units were given at 0 and 2 months. Serum hepatitis A antibody titers were measured after each vaccine dose. An antibody response > or = 33 mIU/ml was considered protective. RESULTS: Screening seropositive rate was 70 of 193 (36%) and 24 patients were available for vaccination. The median antibody titer was markedly lower in liver transplant patients, 0.0 mIU/ml compared to liver failure patients 34.7 mIU/ml (p < 0.001). Liver transplant recipients did not respond to the vaccine (0 of eight patients) compared with seven of 14 liver failure patients (seroconversion rate 50%, p = 0.02). CONCLUSIONS: Liver failure significantly reduces the antibody response to hepatitis A vaccine, and liver transplant recipients were unable to respond to the vaccine. Although this study was small, immunization should be considered early for susceptible patients with chronic liver disease because the development of liver failure may blunt the immunogenicity of the vaccine.
Three areas of high-level scene perception research are reviewed. The first concerns the role of eye movements in scene perception, focusing on the influence of ongoing cognitive processing on the position and duration of fixations in a scene. The second concerns the nature of the scene representation that is retained across a saccade and other brief time intervals during ongoing scene perception. Finally, we review research on the relationship between scene and object identification, focusing particularly on whether the meaning of a scene influences the identification of constituent objects.
Inhibitory control of prepotent responses has been examined by using the antisaccade task, during which a reflexive saccade toward a peripheral onset must be suppressed before an eye movement in the opposite direction from the onset can be executed. In the present experiments, we sought to determine whether older and younger adults would perform similarly on this task. Older adults had a harder time suppressing their reflexive responses, as measured by an increase in the proportion of saccade direction errors. Despite an age-related decline in saccade direction accuracy, the increase in saccade latency associated with the antisaccade condition was the same for both younger and older adults. These results support the view that the effectiveness of inhibitory control declines with age (Hasher & Zacks, 1988; Hasher, Zacks, & May, 1999).
Non-transplant surgery for variceal bleeding includes surgical shunts and devascularization procedures. The indication for such operation are good risk (Childs' A/B) patients who have failed endoscopic therapy. Undecided is the issue of TIPS versus surgical shunt.
Liver transplantation has offered a new avenue for study and understanding of splanchnic and hepatic hemodynamics. This overview presents some of the issues highlighted to date, but emphasizes that this field is open to further study.
In support of an in vivo investigation in swine of the influence of changes in fluid dynamic wall shear on arterial macromolecular permeability, a procedure has been developed to alter the flows in the porcine posterior arterial vasculature by opening and closing a reversible arteriovenous shunt placed on one of the femoral arteries. Laparoscopic techniques were used to place appropriately modified Transonic Systems ultrasonic flow probes on both external and circumflex iliac arteries, and on the terminal aorta. Flow measurements were made prior to shunt placement, and with the shunt open and closed, to measure the influence of altered external iliac artery flow on the distribution to the infrarenal abdominal vessels. Similar experiments were carried out to relate the flow rates in the external iliac arteries to those in the femoral arteries, which are more accessible. Based on the relationships among the measured flow rates, rules have been developed to estimate the major infrarenal flows in the pig, at baseline and with the shunt opened and closed, from only the flow rates measured at the two femoral arteries.
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