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Biomedical subjects

J M Henderson

Publications and source records attributed to J M Henderson.

At least 19 recordsLinked to original sources
PubMed1992

The effect of liver denervation on hepatic hemodynamics during hypovolemic shock in swine.

This study tested the hypothesis that the denervated liver is more susceptible to hypovolemic shock than the normal liver. Fourteen swine, seven nondenervated and seven after liver denervation, were studied during hypovolemic shock to 50% of baseline blood pressure. Hepatic artery and portal vein flows were measured using transonic flow probes, and cardiac output and central venous pressure were measured using Swan-Ganz catheters. Hepatic artery flow fell equivalently in the two groups, from 132 +/- 71 to 94 +/- 17 ml/min in the nondenervated group compared with 149 +/- 56 to 91 +/- 55 ml/min in the denervated group. In contrast, portal flow in the denervated group (276 +/- 71 to 119 +/- 53 ml/min) fell significantly (p less than 0.001) more than in the nondenervated group (289 +/- 135 to 194 +/- 70 ml/min). The 58% reduction from baseline in portal flow in the denervated group compared with the 30% reduction in the nondenervated group suggests that the normal compensatory mechanism to maintain portal flow during hypovolemic shock is neurally mediated. It can be hypothesized that sensory afferent fibers might initiate a feedback to splanchnic vasodilatation in response to reduced portal flow. This study supports the hypothesis that the denervated liver is more susceptible to hypovolemic shock.

Animals↗
PubMed1992

High cardiac output of advanced liver disease persists after orthotopic liver transplantation.

This study measured cardiac output before and 1 or 2 yr after orthotopic liver transplantation in 23 patients. Cardiac output was measured by thermodilution before transplantation and by first-pass radionuclide angiocardiography at follow-up. Study patients were selected as those doing well clinically and by standard laboratory tests at 1-yr and 2-yr reevaluations with no evidence of rejection: six had mild recurrent hepatitis shown on biopsy samples. Hepatocyte function was normal at the time of the study as shown by galactose elimination capacity of 442 +/- 90 mg/min. Medications were cyclosporine and prednisone in all patients, azathioprine in 10 patients and a combination of antihypertensive therapy to maintain diastolic blood pressure less than 90 mm Hg in 20 patients. Mean (+/- S.D.) pretransplantation cardiac output was 9.1 +/- 3.1 L/min and remained elevated at 8.3 +/- 2.1 L/min 1 yr, and 9.6 +/- 2.6 L/min (n = 13) 2 yr after transplantation. A significant (p less than 0.001) correlation was found between pretransplant and follow-up cardiac output. End diastolic, end systolic and stroke volumes are all increased in a pattern similar to that seen in end-stage cirrhosis. These data show that the high cardiac output of the hyperdynamic state of advanced liver disease persists after liver transplantation. The mechanisms and consequences of this require further study.

Cardiac Output↗
PubMed1992

Hemodynamics during liver transplantation: the interactions between cardiac output and portal venous and hepatic arterial flows.

Liver blood flow and systemic hemodynamics were measured intraoperatively in 34 patients after liver transplantation. Ultrasound transit-time flow probes measured hepatic arterial and portal venous flow over 10 to 75 min 1 to 3 hr after reperfusion. Cardiac output was measured by thermodilution. Mean cardiac output was 9.5 +/- 2.8 L/min; the mean total liver blood flow of 2,091 +/- 932 ml/min was 23% +/- 11% of cardiac output. Mean portal flow of 1,808 +/- 929 ml/min was disproportionately high at 85% +/- 10% of total liver blood flow. Correlation analysis showed a significant (p less than 0.01; r = 0.42) correlation between cardiac output and portal venous flow and a trend toward negative correlation (p = 0.087) between cardiac output and hepatic arterial flow. These data show that increased flow in the newly transplanted liver is predominantly portal venous flow and is associated with high cardiac output and reduced hepatic arterial flow. In the last 13 patients studied, portal flow was reduced by 50% and the hepatic artery response was measured. We saw a significant (p less than 0.05) increase in hepatic artery flow from 322 +/- 228 to 419 +/- 271 ml/min, indicating an intact hepatic arterial buffer response. The hepatic artery response also showed that it is a reversible rather than a fixed resistance that contributes to the low hepatic artery flow in these patients.

Blood Pressure↗
PubMed1992

Endoscopic variceal sclerosis does not increase the risk of portal venous thrombosis.

In this study the risk of thrombosis in the portal venous system was assessed in patients with chronic variceal bleeding undergoing sclerotherapy. Twenty-two patients with cirrhosis were prospectively studied with angiography before initiation of sclerotherapy and at mean (+/- SD) 26 +/- 17-month (range, 8-63 months) follow-up. Sclerotherapy consisted of flexible endoscopy, intravariceal and paravariceal, using sodium morrhuate (1.5%-2%) and sodium tetradecyl sulfate (0.5%-1.5%), to obliteration. The mean number of sessions was 6.5 +/- 2.2 (range, 3-11), with a mean total amount of sclerosant of 62 +/- 25 mL (range, 25-112 mL). No patient developed splenic or portal vein thrombosis as shown by arteriography. The flow patterns of portal perfusion, vessel size, and coronary vein visualization showed no significant change. Only one patient had spontaneous reversal of portal flow. Splenic vein histology, examined in five patients in whom sclerotherapy failed and who required shunt surgery, was not significantly different from that in eight patients who had no prior sclerotherapy. It is concluded that under the conditions of the current study, chronic sclerotherapy did not increase the risk of thrombosis in the portal venous system and did not significantly alter the histology of the portal hypertensive splenic vein.

Angiography↗
PubMed1992

Distal spleno-renal shunt versus endoscopic sclerotherapy in the prevention of variceal rebleeding. A meta-analysis of 4 randomized clinical trials.

Meta-analysis was used to evaluate 4 clinical trials comparing distal spleno-renal shunt (DSRS) with endoscopic sclerotherapy (EVS) in the prevention of variceal rebleeding: the interval between bleeding and therapy ranges from < 14 days to > 100 days. A questionnaire was sent to each author of the published trials concerning methods, definitions and results of the trials in order to obtain more detailed and up-to-date information. The selected end-points for the meta-analysis were: rebleeding, mortality and chronic encephalopathy. Analysis of the results in the questionnaires was made using the method proposed by Collins. The pooled relative risk (i.e. the combined Odds ratio of each trial as an estimate of overall efficacy) of rebleeding was statistically reduced by DSRS (0.16; 95% confidence interval 0.10-0.27). Despite this, the overall risk of death following DSRS was only marginally decreased (0.78; 95% confidence interval 0.47-1.29); the lack of homogeneity in the results does not permit any significant conclusions on this end-point. However, in non-alcoholic patients, the decrease in risk of death was greater, and this without heterogeneity, following DSRS than EVS (0.59; 95% confidence interval 0.23-1.50). The overall risk of chronic encephalopathy was slightly increased after DSRS (1.86; 95% confidence interval 0.90-3.86). In conclusion, DSRS significantly reduced the risk of rebleeding compared to EVS without increasing the risk of chronic hepatic encephalopathy. However, DSRS did not significantly affect the overall death risk. Only in non-alcoholic disease did it seem to show an advantage over EVS.

Brain Diseases↗
PubMed1992

Identifying objects across saccades: effects of extrafoveal preview and flanker object context.

Two object-naming experiments explored the influence of extrafoveal preview information and flanker object context on transsaccadic object identification. Both the presence of an extrafoveal preview of the target object and the contextual constraint provided by extrafoveal flanker objects were found to influence the speed of object identification, but the latter effect occurred only when an extrafoveal preview of the target object was not presented prior to fixation. The context effect was found to be due to facilitation from related flankers rather than inhibition from unrelated flankers. No evidence was obtained for the hypothesis that constraining context can increase the usefulness of an extrafoveal preview of a to-be-fixated object.

Adult↗
PubMed1992

Object identification in context: the visual processing of natural scenes.

When we view a natural visual scene, we seem able to determine effortlessly the scene's semantic category, constituent objects, and spatial relations. How do we accomplish this visual-cognitive feat? The commonly held explanation is known as the schema hypothesis, according to which a visual scene is rapidly identified as a member of a semantic category, and predictions generated from the scene category are then used to aid subsequent object identification. In this paper I will first outline and offer a critique of the evidence that has been taken to support the schema hypothesis. I will then offer an alternative framework for understanding scene processing, which I will call the local-processing hypothesis. This hypothesis assumes a modular, informationally-encapsulated architecture, and explicitly includes the role of covert visual attention in scene processing.

Attention↗
PubMed1992

Selective shunt in the management of variceal bleeding in the era of liver transplantation.

This study reports the Emory experience with 147 distal splenorenal shunts (DSRS) and 110 orthotopic liver transplants (OLT) between January 1987 and December 1991. The purpose was to clarify which patients with variceal bleeding should be treated by DSRS versus OLT. Distal splenorenal shunts were selected for patients with adequate or good liver function. Orthotopic liver transplant was offered to patients with end-stage liver disease who fulfilled other selection criteria. The DSRS group comprised 71 Child's A, 70 Child's B, and 6 Child's C patients. The mean galactose elimination capacity for all DSRS patients was 330 +/- 98 mg/minute, which was significantly (p less than 0.01) above the galactose elimination capacity of 237 +/- 82 mg/minute in the OLT group. Survival analysis for the DSRS group showed 91% 1-year and 77% 3-year survival, which was better than the 74% 1-year and 60% 3-year survivals in the OLT group. Variceal bleeding as a major component of end-stage disease leading to OLT had significantly (p less than 0.05) poorer survival (50%) at 1 year compared with patients without variceal bleeding (80%). Hepatic function was maintained after DSRS, as measured by serum albumin and prothrombin time, but galactose elimination capacity decreased significantly (p less than 0.05) to 298 +/- 97 mg/minute. Quality of life, measured by a self-assessment questionnaire, was not significantly different in the DSRS and OLT groups. Hospital charges were significantly higher for OLT (median, $113,733) compared with DSRS ($32,674). These data support a role for selective shunt in the management of patients with variceal bleeding who require surgery and have good hepatic function. Transplantation should be reserved for patients with end-stage liver disease. A thorough evaluation, including tests of liver function, help in selection of the most appropriate therapeutic approach.

Adult↗
PubMed1992

Prevalence of invasive cytomegalovirus disease with administration of muromonab CD-3 in patients undergoing orthotopic liver transplantation.

OBJECTIVE: To assess the association of cytomegalovirus (CMV) disease with the administration of muromonab CD-3 (OKT-3) in patients undergoing liver transplant; specifically, to assess the risk of OKT-3 use as an agent for rejection prophylaxis and as an agent for therapy of rejection. DESIGN: Retrospective review of medical records. STUDY POPULATION: 83 liver transplant recipients (43 men, 40 women) with a mean age of 41.5 years (range 16-62). DATA EXTRACTION: The medical record for each liver transplant recipient was reviewed and analyzed for the following variables: (1) preoperative recipient CMV serology, (2) donor CMV serology, (3) incidence of invasive CMV disease, (4) administration of OKT-3, (5) postoperative administration time of OKT-3, and (6) the relationship between the administration of OKT-3 and the prevalence of invasive CMV disease. RESULTS: OKT-3 was administered to 34 of 83 (40.9 percent) liver remainder received OKT-3 as rejection rescue. All patients received OKT-3 5 mg iv for 14 days. Seventeen of the 34 patients receiving OKT-3 (50 percent) developed invasive CMV disease; 58.8 percent of the patients (20/34) receiving OKT-3 were given the agent within the first 14 postoperative days. Sixteen of these 20 patients (80 percent) developed invasive CMV disease. One of 14 patients (7.1 percent) who received OKT-3 after the first 14 postoperative days developed invasive CMV disease. Of those patients 94 percent (16/17) received OKT-3 in the first 14 postoperative days. This prevalence differed significantly from those receiving OKT-3 after the 14th postoperative day and those who did not receive OKT-3 at any time during their hospital course. CONCLUSIONS: The patients who received early administration of OKT-3 in our study had a greater risk of invasive CMV disease than did those who received OKT-3 later in the hospital course.

Adolescent↗
PubMed1992

Persistence of portosystemic collaterals and splenomegaly on CT after orthotopic liver transplantation.

OBJECTIVE: The appearances of portosystemic collaterals and splenomegaly on CT before and after liver transplantation were evaluated. MATERIALS AND METHODS: The records of 54 patients undergoing liver transplantation during a 2.5-year period were reviewed retrospectively. Twenty-five of these patients, in whom both a preoperative abdominal CT scan and a follow-up CT scan at least 1 year after transplantation had been obtained, were clinically well and had had no significant episodes of rejection, severe recurrent hepatitis, or other complication at the time of study. A total of 94 abdominal CT scans in these patients were reviewed to assess changes in portosystemic collaterals and splenic volume. RESULTS: At 6 months after transplantation, portosystemic collaterals at one or more sites were seen in 14 (74%) of the 19 patients scanned at this time in whom collaterals had been seen on CT preoperatively. At 1 year after transplantation, splenic hilar collaterals persisted in 64% of patients, splenocolic ligament collaterals in 50%, retroperitoneal collaterals in 38%, and peripancreatic collaterals in 38% of patients with preoperative varices at these sites who were examined with CT at this interval. Splenic hilar, coronary, and retroperitoneal collaterals were found to persist for up to 4 years after transplantation in the single patient examined at that time. Splenic volume decreased in 94% of patients examined after transplantation, with a mean reduction of 60 +/- 19%. However, the spleen remained significantly enlarged in 56% of patients. CONCLUSION: We conclude that portosystemic collaterals and splenomegaly frequently persist after liver transplantation, but that this finding need not indicate recurrence of hepatic disease or other posttransplantation complications.

Adult↗
PubMed1992

Liver transplantation for portal hypertension.

Liver transplantation is among the therapies that may be required for patients with variceal bleeding. The indication for transplantation is end-stage liver disease, not the variceal bleeding per se. Selection of patients is based on full evaluation that includes medical necessity, absence of medical contraindication, and psychosocial suitability. Decision algorithms for variceal bleeding must recognize that transplantation may be the endpoint of treatment, and other treatments should take this into consideration. Specific problems related to prior surgery for variceal bleeding should be defined before transplantation, and management strategies should be determined. The outcome for patients with end-stage cirrhosis and variceal bleeding has been dramatically improved by addition of transplantation to the treatment options.

Algorithms↗
PubMed1991

Selective splenocaval shunt. Report of 26 cases and review of the literature.

Splenocaval shunting was performed in 26 patients for the treatment of variceal bleeding. The indications for this alternative selective shunt were congenital anomalies of the left renal vein, inadequate outflow from the left renal vein on preoperative venography, or an anatomic relationship of the splenic vein favoring direct splenocaval rather than splenorenal anastomosis. Technical considerations in which splenocaval shunts differ from distal splenorenal shunting relate to exposure of the vena cava. Operative mortality was 7.7% (2/26). Immediate shunt patency was documented in 23 of 24 patients studied, and all 14 shunts studied at 13 to 57 months were patent. Portal perfusion was maintained in 95% (20/21) of the patients when studied at 7 to 10 days after shunting and in 57% (8/14) at late follow-up. This experience with distal splenocaval shunting has reaffirmed its place as an alternative technique to selective distal splenorenal shunts, particularly when the left renal vein is abnormal.

Adolescent↗
PubMed1991

Therapy of the Kasabach-Merritt syndrome with cryoprecipitate plus intra-arterial thrombin and aminocaproic acid.

A patient with the Kasabach-Merritt syndrome with disseminated intravascular coagulopathy and congestive heart failure due to a giant hepatic cavernous hemangioma achieved thrombosis of his tumor with a combination of cryoprecipitate plus intra-arterial thrombin and epsilon aminocaproic acid. This was documented by an absence of Indium 111-labelled platelet sequestration, marked decrease in thrombin:antithrombin complex generation, and normalization of platelet count and fibrinogen. Interventional angiography with aminocaproic acid and thrombin is advocated in patients whose tumors are amenable to such an approach so as to avoid a systemic antifibrinolytic state.

Aged↗
PubMed1991

The role of continued drinking in loss of portal perfusion after distal splenorenal shunt.

Fifty percent of patients with alcoholic cirrhosis who undergo distal splenorenal shunting for variceal bleeding lose portal perfusion within 1 year. Although it was previously considered that this loss of portal flow was irrevocable, the present study shows that with resolution of alcoholic hepatitis, portal perfusion can be restored. A 34-year-old patient with alcoholic liver disease and a distal splenorenal shunt lost portal perfusion 1 year after the operation. He had continued to drink alcohol and had high sinusoidal pressure. Following forced abstinence over the next 2 years, his sinusoidal pressure fell, liver volume decreased, results of liver biopsy improved, and portal perfusion was restored. Shunt patency was documented, and the same collaterals from the portal vein to the shunt could still be visualized as had been seen when portal flow was absent. Restoration of portal perfusion was attributed to decreased intrahepatic resistance secondary to abstinence from alcohol. A return to drinking in the next 9 months led to alcoholic hepatitis and once again loss of portal perfusion. This study places emphasis on increased intrahepatic resistance rather than the development of portal-to-shunt collaterals as important in the loss of portal flow in such patients.

Adult↗
PubMed1991

Stimulus discrimination following covert attentional orienting to an exogenous cue.

Five experiments explored exogenous covert visual-attentional orienting following a brief peripheral cue. On each trial an attentional cue was followed by a stimulus in an empty field at 1 of 8 locations on an imaginary circle centered on the fixation point. The cued area size and the cue-target spatial relation were manipulated. Accuracy and response time were affected by the exogenous cue validity. Attention was allocated to a specific location in a visual quadrant: A target at an uncued location in a quadrant was not facilitated as much as target at the cued location, and a target in a different quadrant was inhibited in relation to a neutral condition. Cuing 2 locations in a quadrant was not as facilitative for targets at the cued locations or as inhibitive for targets at other locations compared with cuing a single location in a quadrant. Results are discussed in the context of several extent models of covert visual-spatial attention.

Adult↗
PubMed1991

A comparison of standard Madopar and controlled release Madopar in Parkinson's disease.

In a randomised, double-blind cross-over study, objective measures were used to compare the effect of a single oral dose of a standard preparation of levodopa-benserazide (Madopar M) with a sustained-release preparation (Madopar HBS) in 9 Parkinsonian patients with 'end of dose deterioration'. The response of patients to an optimised regimen of each preparation was also assessed using a patient diary. In all patients the onset of effect of Madopar HBS following a single dose was delayed compared with Madopar M. The duration of effect of a single dose of Madopar HBS was substantially (38-120%) longer than Madopar M in five patients and the same or shorter in four patients. According to the patients' diaries, six patients noted an increase in 'on' hours while on Madopar HBS. The duration and severity of dyskinesia was similar for the two preparations. Madopar HBS is likely to be useful in some Parkinsonian patients with 'end of dose deterioration'. As the effect of each dose is delayed it is probably best given in combination with standard Madopar.

Adult↗