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Biomedical subjects

R Gordon

Publications and source records attributed to R Gordon.

At least 109 records · Page 6Linked to original sources
PubMed1994

Liver transplantation for neonatal hepatitis as compared to the other two leading indications for liver transplantation in children.

Neonatal hepatitis is a syndrome of unknown etiology occurring in children with viral liver disease, as well as children with unidentified disorders of bile salt synthesis and other poorly understood metabolic diseases. It is characterized by jaundice, giant cell hepatitis and rare liver failure necessitating liver transplantation. In the present investigation, the outcome of liver transplantation performed in 16 children with neonatal hepatitis at the investigators' institution was determined from 1 January 1989 to 31 December 1991. The results were compared to those obtained in 288 children transplanted for biliary atresia and 66 children transplanted for recognized metabolic liver disease. The children transplanted for neonatal hepatitis (4.1 +/- 1.3 years) and metabolic liver disease (5.8 +/- 0.6 years) were older than those transplanted for biliary atresia (3.3 +/- 0.2 years) (p < 0.01), but did not differ in terms of sex, ABO type, UNOS status or year in which the transplant procedure was performed. Interestingly, first allograft survival was equal in the children with neonatal hepatitis (74%) and those with metabolic liver disease (74%), but was greater than that for children transplanted for biliary atresia (68%) (p < 0.01). Despite this significant difference in first graft survival, no differences in 5-year survival were seen for the three groups (81% for neonatal hepatitis, 68% for biliary atresia and 79% for metabolic liver disease).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

A projection access order for speedy convergence of ART (algebraic reconstruction technique): a multilevel scheme for computed tomography.

The practical performance of algebraic reconstruction techniques (ART) for computed tomography (CT) depends heavily on the order in which the projections are considered. Complete orthogonalization, notwithstanding its theoretical justification, is not feasible because the computational time is prohibitive. The authors report here a scheme that yields the most efficient reconstruction without orthogonalization: projections are organized and accessed in a nominally multilevel fashion. Each level makes the best use of the image information reconstructed in the preceding levels. If the number of projections is a power of two. Then the access orders are exactly that for the 1D FFT. The authors' scheme can be easily implemented. Using it, one iteration of ART yields a high-quality image. Experimental results of this algorithm are demonstrated and compared with the results from the conventional sequential method and also random ordering. Comparisons show that this scheme is superior. ART is better in image quality than the Fourier back-projection algorithm, at least for a smaller number of projections. Since the authors have made it much more efficient in computational speed, ART could now find widespread use in medical imaging.

Algorithms↗
PubMed1994

Signal-detection analysis of the Müller-Lyer and the Horizontal-Vertical illusions.

Perceptual error in the Müller-Lyer and the Horizontal-Vertical illusions was quantified using nonparametric signal-detection measures of sensitivity and response bias. Sensitivity scores were positively related to signal strength with the greatest values observed for the strongest signals. Sensitivity at each signal strength did not differ between the two illusions. Response-bias scores were inversely related to signal strength, with the most conservative biases observed for the strongest signals. Response biases for each signal strength were significantly more conservative for the Horizontal-Vertical than for the Müller-Lyer illusion.

Adult↗
PubMed1994

Burnout and career-choice regret among family practice physicians in early practice.

OBJECTIVE: Burnout and career-choice regret among physicians in early practice may contribute to physician impairment and attrition as well as patient dissatisfaction. METHOD: Fifty residency-trained family physicians in early practice completed the Maslach Burnout Inventory and a questionnaire on career-choice, demographics, and practice characteristics. RESULTS: The sample showed moderate burnout related to emotional exhaustion and depersonalization of patients but low burnout related to lack of personal accomplishment. Although only 52% reported that they would definitely choose a medical career again, 70% reported that they would definitely choose the specialty of family practice again. At the 0.01 level of significance, those who worked more hours were more emotionally exhausted, and those with children and those with more children under the age of 5 reported less depersonalization. CONCLUSIONS: This sample of physicians in early practice reported slightly less burnout and less specialty-choice regret than a comparable sample of family practice residents, suggesting possible attenuation of burnout with the transition from training to practice. Nonetheless, the importance of overwhelming time demands as a precipitant of exhaustion and potential physician impairment is noted.

Burnout, Professional↗
PubMed1993

Lack of association between HLA antigen DR3 and alpha 1-antitrypsin deficiency in liver transplant recipients.

The relationship between alpha 1-antitrypsin deficiency (alpha 1-ATD) and the HLA antigen system was studied in 32 liver transplant recipients. Despite previous reports of an association of HLA antigen DR3 with homozygosity for alpha 1-AT ZZ, no such association was seen in this population of alpha 1-ATD homozygous ZZ patients with advanced hepatic disease. Thus, the reported association of HLA class II antigens and homozygosity for the Z allele for alpha 1-AT may be an artifact of either a small study population or geographic inbreeding and a coincidental association of certain HLA antigens with the presence of homozygosity for the Z allele of alpha 1-AT.

Adolescent↗
PubMed1993

Measurement of wrist, metacarpophalangeal joint, and thumb extension strength in a normal population.

An objective method of measuring isometric wrist, finger (metacarpophalangeal joints) and thumb extension strength was developed, and values for a normal population were defined. Disability due to extensor dysfunction was not assessed in this study. The testing technique involved the use of a load cell myometer held in a specially constructed jig. A total of 2232 measurements in 372 persons were made. Mean values for the strength of extension were as follows: men--wrist, 13 kg; metacarpophalangeal joint, 6 kg; thumb, 3 kg; women--wrist, 7 kg; metacarpophalangeal joint, 4 kg; thumb, 2 kg. Strength was greatest in the third decade and decreased in each subsequent age group. Wrist extension strength was 10% greater in the dominant hand. Interrater and test-retest reliability were assessed and found to be satisfactory. The method is proposed primarily as a clinical research tool, providing the clinician with an objective means of assessing wrist, metacarpophalangeal joint, and thumb extensor function. Potential applications include measurements of recovery after radial nerve injury or grafting and after other reconstructive procedures to restore extensor function.

Adult↗
PubMed1993

Detection of renin mRNA in aldosterone-producing adenomas by polymerase chain reaction.

1. Ribonucleic acid (RNA) was extracted from two normal human adrenal cortices and from five aldosterone-producing adenomas (APA). 2. The five APA could be categorized, on the basis of in vivo aldosterone responsiveness to angiotensin infusion and upright posture, into two APA responsive to both stimuli, two responsive only to angiotensin infusion, and one unresponsive to either stimulus. 3. RNA was reverse transcribed and coamplified by polymerase chain reaction (PCR) with an internal standard of renin complementary DNA (cDNA) containing a 60 base pair insertion. Renin mRNA in the APA was compared with normal adrenals. 4. Renin mRNA was greater than normal in the two APA responsive to both stimuli and less than, or similar to normal, in the two APA responsive only to angiotensin infusion. Renin mRNA was also less than, or similar to normal, in the APA unresponsive to either stimulus. 5. These findings support a possible role for adrenal renin in the development and biochemical behaviour of angiotensin-responsive APA.

Adenoma↗
PubMed1993

Use of capnography for assessment of the adequacy of alveolar ventilation during weaning from mechanical ventilation.

A prospective study was conducted to determine the reliability of noninvasive end-tidal CO2 (PETCO2) monitoring as a reflection of arterial CO2 tension (PaCO2) during weaning from mechanical ventilation (MV). Simultaneous PaCO2 and PETCO2 determinations were compared during MV and again during a spontaneous breathing trial just before returning the patient to MV. Three groups of patients recovering from acute respiratory failure were evaluated. Group 1 consisted of 16 patients (28 observations) without parenchymal lung disease. Group 2 consisted of 22 patients (31 observations) with alveolar filling diseases. Group 3 was composed of 13 patients (22 observations) with emphysema. Significant Pearson correlation coefficients were demonstrated between PaCO2 and PETCO2 during both MV and spontaneous breathing in all three groups. Significant correlation was also demonstrated between the change in PaCO2 and the change in PETCO2 associated with weaning for each group; however, the degree of correlation varied between groups. Our data suggest that capnography offers a reasonable estimate of PaCO2 and changes in PaCO2 during weaning in patients without parenchymal lung disease. However, PETCO2 is less sensitive to changes in PaCO2 for patients with parenchymal lung disease, particularly patients with emphysema. Interpretation of capnographic data requires a full understanding of its limitations. An approach to capnographic monitoring during weaning is discussed.

Aged↗
PubMed1993

Pentostatin increases the acute toxicity of high dose cyclophosphamide.

One dose of pentostatin was added to a standard cyclophosphamide (CY) based transplant regimen in two patients in an attempt to decrease the rate of non-engraftment in haploidentical allogeneic BMT. Despite a normal cardiac history and evaluation prior to transplant, both patients suffered fatal cardiac toxicity within 48 h of receiving the chemotherapy. This phenomenon was further investigated in an animal model. Laboratory rats were treated with progressive doses of CY in a range that produces acute cardiac toxicity. Successive groups of rats were treated with either pentostatin or fludarabine and CY at 400 mg/kg. Neither pentostatin nor fludarabine alone produced early mortality. However, a marked increase in early mortality was noted in those animals treated with pentostatin and high-dose CY. The addition of fludarabine did not increase the early toxicity of CY. Autopsy revealed no gross or microscopic abnormalities in the animals. The implications of adding agents that interfere with adenosine metabolism to CY based transplant regimens is discussed.

Adult↗
PubMed1993

Effects of felbamate and other anticonvulsant drugs in two models of status epilepticus in the rat.

Felbamate was compared with several antiepileptic drugs for protective effects in two rat models of status epilepticus. Felbamate was ten times more potent against pilocarpine-induced seizures in lithium-treated rats than in lithium-free animals. Diazepam, valproate and phenobarbital were effective in both the high dose pilocarpine and lithium-pilocarpine models. On the other hand, phenytoin was ineffective in both models, whereas carbamazepine displayed protective effects only in the lithium-pilocarpine model.

Animals↗
PubMed1993

Chronic recurrent esophageal strictures treated with balloon dilation in children with autosomal recessive epidermolysis bullosa dystrophica.

Two children (8- and 17-yr old) with autosomal recessive epidermolysis bullosa dystrophica and chronic esophageal strictures were treated with repeated balloon dilations. General anesthesia was by face mask adapted specifically for this procedure, with careful attention to avoid skin and mucus membrane damage. A balloon dilator positioned fluoroscopically over an angiographic guidewire was gently inflated until narrowings resolved. Dilations have been performed every 1-11 [4.3 +/- 3.2 (mean +/- SD)] months in the younger patient over the last 4.3 yr, and every 8-20 (14.5 +/- 5.9) months in the older patient over the last 4.8 yr, without serious complications. Both patients were able to swallow normal foods following dilations. Repeated balloon dilations of esophageal strictures in patients with epidermolysis bullosa dystrophica can be done safely. Further studies are indicated to determine its effectiveness and appropriateness as an alternative to colonic interposition.

Adolescent↗
PubMed1992

Cytomegalovirus infection of the upper gastrointestinal tract following liver transplantation--incidence, location, and severity in cyclosporine- and FK506-treated patients.

One hundred and forty randomly selected liver transplant recipients were studied before and after primary orthotopic liver transplantation for the presence or absence of CMV enteritis. Following OLTx, 65 patients were treated with cyclosporine A and 75 were treated with FK506. The two groups were similar with regard to the incidence, location, and outcome of their upper gastrointestinal CMV infection. Prior to OLTx, only one patient had evidence of enteric CMV infection. The incidence of CMV enteritis post-OLTx was 27.7% in the CsA-treated group and 20% in the FK-treated group. During the first posttransplant month, no patient in the FK-treated group developed CMV enteritis, compared with 11.5% of the patients who were treated with CsA (P less than 0.05). Gastric CMV was found in over 80% of those positive for any organ in either group. In addition to CMV infection of the upper gastrointestinal tract, clinically evident CMV disease involved more nonenteric organs in the CsA-treated group than in the FK-treated group. In the CsA-treated group, CMV-negative patients had a statistically higher 1-year survival rate (100%) than CMV-positive patients (77.8%) (P less than 0.05). In the FK-treated group, no difference in survival was observed between CMV-positive or CMV-negative cases at 1 year. Of the patients on CsA, 20% received OKT3 for persistent rejection, as compared with 13% in the FK-treated group. The patients receiving both CsA and OKT3 had a higher rate of upper gastrointestinal CMV infection than did FK-treated patients who also received OKT3 therapy (38.5% versus 20%, respectively). Based upon these data, it can be concluded that (1) patients receiving FK have a lower incidence of enteric CMV infection; (2) following OLTx, upper gastrointestinal CMV infection presents later in FK-treated patients; (3) the stomach is the most frequently involved organ in the UGIT; (4) FK-treated liver recipients have less severe enteric CMV infection than do CsA-treated patients; (5) enteric CMV is not a major cause of mortality in liver transplant recipients; and (6) in patients receiving FK, those who require OKT3 therapy do not appear to be at a greater risk for the development of CMV enteritis than those who do not.

Adolescent↗
PubMed1992

The association of IgA deficiency but not IgG or IgM deficiency with a reduced patient and graft survival following liver transplantation.

Recipients of solid organ allografts require lifelong immunosuppression in order to prevent graft rejection and to maintain graft function. In general, such immunosuppression greatly impairs the cellular immune system, as this level of the immune system is principally responsible for self and non-self recognition. The consequences of allograft transplantation in terms of patient and graft survival when transplants are given to individuals who have a preexisting humoral immune deficiency characterized by a deficiency of the serum levels of one or more of the major Ig classes have not yet been reported. From February 1, 1981 through December 31, 1990, a total of 43 adult patients with a deficiency of 1 or more Ig classes received a ABO-matched liver allograft at this institution. This sample represents 2.5% of a total of 1684 adults transplanted during this interval. These 43 liver graft recipients could be divided into 3 major groups based upon the presence of an IgG, IgM, or IgA deficiency. IgG deficiencies were defined as levels less than 50 mg/dl. Patient and graft survival for the IgA-deficient group was significantly reduced (P less than 0.04 and P less than 0.009, respectively) compared with both the IgG- and IgM-deficient groups. The latter two groups did not differ from controls without an Ig deficiency for these same two endpoints. The major causes of death in the IgA-deficient group were sepsis and opportunistic infection. A third of the deaths in the IgA-deficient group occurred in the perioperative period (first 30 days) while greater than 50% of the deaths occurred within the first 3 months, and all deaths occurred before the first year. Based upon these data, the following conclusions can be made: (1) serum IgA deficiency but not IgG or IgM deficiency is associated with an increased post-OLTx death and graft loss rate; (2) the majority of these deaths are due to sepsis or an opportunistic infection; and (3) most of the deaths occur early. These data suggest that recognition of a deficiency of IgA prior to organ grafting necessitates meticulous attention to the prevention of infection in the immediate perioperative period if patient and graft survival of these patients is to be improved.

Adult↗
PubMed1992

Hepatic artery pseudoaneurysm ligation after orthotopic liver transplantation--a report of 7 cases.

Pseudoaneurysm (PA) is a rare but life-threatening complication of liver transplantation. The authors present their experience on 7 patients treated by ligation of a post-OLT PA. Hepatic artery ligation or embolization was performed from 10 to 70 days after liver transplantation. Of the seven patients, four survived, one developed a biliary stricture, treated by percutaneous balloon dilatation, two died of a complication not related to treatment, and one died of multiple organ failure.

Adult↗
PubMed1992

Ethanol-associated alterations in the kinetics of putrescine uptake and metabolism by the regenerating liver.

Biosynthesis of the polyamines, putrescine, spermidine, and spermine is required for DNA synthesis and liver regeneration after partial hepatectomy. We have previously reported that chronic ethanol consumption impairs polyamine synthesis and significantly retards liver regeneration after partial hepatectomy. In those studies, supplementation with putrescine restored hepatic DNA synthesis in ethanol-fed rats but exerted no effect in pair-fed controls. These differences in the response to putrescine treatment may have resulted from ethanol-associated differences in hepatic uptake, release, or metabolism of putrescine. To resolve these issues and define more completely how putrescine treatment affects DNA synthesis, we now assess the kinetics of putrescine uptake and metabolism after intraperitoneal or intravenous injection of radiolabeled putrescine (1.2 mmol/kg, specific activity 1 microCi/mmol) into rats fed 36% ethanol diets or isocaloric, nonethanol diets for 6 weeks prior to partial hepatectomy. After putrescine treatment, hepatic putrescine concentrations were greater in ethanol-fed rats than controls. Differences in post-treatment hepatic putrescine levels between ethanol and pair-fed groups could not be explained by differences in the rates of hepatic putrescine uptake or excretion into bile; residual de novo synthesis of putrescine from ornithine or metabolism of hepatic putrescine to its polyamine products, spermidine and spermine. Indeed, supplemental putrescine was not appreciably converted to spermidine or spermine in either ethanol or control rats. Hence, these latter polyamines are unlikely to be responsible for the treatment-associated improvement in DNA synthesis that has been noted in ethanol-fed rats. This suggests that putrescine itself acts to restore hepatic DNA synthesis in ethanol-fed rats.

Alcoholism↗