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Biomedical subjects

A Keogh

Publications and source records attributed to A Keogh.

At least 37 records · Page 2Linked to original sources
PubMed1998

Maintained function of primary human hepatocytes by cellular interactions in coculture: implications for liver support systems.

The application of primary hepatocytes in hybrid artificial liver systems has been hampered by the gradual loss of differentiated morphology and function in vitro. Therefore, we have established a coculture model of autologous human hepatocytes and biliary epithelial cells (BEC) in collagen gel in the presence of hepatotrophic growth factors. Furthermore, we examined the effect of hepatocyte cell perfusion in a women multicompartment capillary membrane system. Normal hepatocytes isolated from human liver produced albumin for more than 2 weeks in serum-free media, and were further stimulated by conditioned medium. When cocultured with BEC, albumin secretion was greatly enhanced, suggesting that cellular interactions promote tissue-specific differentiation. When perfused in bioreactors, albumin levels were maintained at steady state for longer than 2 weeks. These data indicate that differentiation of primary hum hepatocytes can be maintained by coculture interactions and three-dimensional hybrid organ devices, providing appropriate growth factors and matrix for tissue regeneration.

Cell Communication↗
PubMed1998

Ocular complications of heart, lung, and liver transplantation.

AIM: To document the nature and frequency of ocular complications in a large group of patients who underwent heart, lung, or liver transplantation. METHODS: A retrospective audit of the medical records of all patients undergoing heart, lung, or combined heart-lung transplantation at St Vincent's Hospital, Sydney, or liver transplantation at Royal Prince Alfred Hospital Sydney, was performed to detect patients with symptomatic ocular complications following transplantation. 19 of 860 patients were identified as having ocular complications. RESULTS: Ocular complications occurred in 2% of patients with 65% of these being opportunistic infections. Herpes group viral retinitis (77%) and fungal chorioretinitis (22%) were seen. Other complications included choroidal pseudolymphoma, central retinal vein occlusion, herpes zoster ophthalmicus, herpetic keratitis, dacryocystitis, cyclosporin retinopathy, and rifabutin associated uveitis. CONCLUSION: Herpes group viral retinitis was the most common ocular opportunistic infection and occurred most frequently during the second year after transplantation. Delayed diagnosis was associated with poor visual outcome.

Adult↗
PubMed1998

Adjunctive use of inhaled nitric oxide during implantation of a left ventricular assist device.

BACKGROUND: The aim of this study was to evaluate the efficacy of inhaled nitric oxide in the prevention and reversal of pulmonary hypertension during and after left ventricular assist device implantation. METHODS: Inhaled nitric oxide (20 ppm) was administered to seven consecutive patients undergoing implantation of a left ventricular assist device at the time of implantation and for the first 24 hours after operation. RESULTS: Withdrawal of inhaled nitric oxide at 24 hours after operation was associated with a significant rise in both the transpulmonary gradient (from 8+/-1 to 14+/-2 mm Hg, p < 0.01) and in pulmonary vascular resistance (from 110+/-19 to 196+/-32 dynes x sec x cm[-5], p < 0.01). In two patients, the rise in pulmonary vascular resistance resulted in a critical fall in left ventricular assist device flow and hemodynamic deterioration, necessitating urgent reinstitution of inhaled nitric oxide. CONCLUSION: The administration of inhaled nitric oxide at the time of left ventricular assist device implantation prevents rises in pulmonary vascular resistance that in some patients result in critical reductions in left ventricular assist device flow. We suggest that inhaled nitric oxide is a useful adjunctive treatment that should be routinely available at the time of left ventricular assist device implantation.

Administration, Inhalation↗
PubMed1998

Evaluation of the function of primary human hepatocytes co-cultured with the human hepatic stellate cell (HSC) line LI90.

Most bioartificial liver devices utilise primary hepatocytes alone although some have considered the use of non parenchymal cells in addition. However the effects of co-culture of human hepatocytes with different sinusoidal cell types has not been fully investigated. In this study we have examined the influence of co-culturing primary human hepatocytes with the human hepatic stellate cell (HSC) line, LI90. Cultures were monitored by light microscopy and on days 4, 8 and 14 urea synthesis and cytochrome P450 activity were measured. Morphologically LI90 cells proliferated to fill spaces between and into adjacent islands of hepatocytes. On day 14 cytochrome P450 activity in co-culture was significantly improved compared to hepatocytes cultured alone. By contrast, urea synthesis in hepatocytes was unaffected by single or co-culture. Therefore it can be concluded that a combination of primary human hepatocytes with LI90 cells is beneficial for growth and some stability of hepatocytes and may therefore be appropriate for seeding bioartificial liver devices.

Cell Division↗
PubMed1997

Variations in the relative mRNA levels of actins and myosin heavy chains do not produce corresponding differences in their proteins in the adult human heart.

This paper examines the quantitative relationship between the expression of myosin heavy chain (MHC) and actin at both the levels of their mRNAs and their proteins. Explanted human left ventricle tissues were obtained from non-diseased (ND) individuals and from dilated cardiomyopathy (DCM) patients with terminally failing hearts who underwent heart transplantation. We found: (1) there are substantial differences in the stoichiometry of sarcomeric MHC and actin transcripts in hearts of DCM patients as well as in ND individuals; (2) there are substantial differences between levels of total sarcomeric actin transcripts from different individual patients; (3) by and large variations in transcript levels between samples from the same heart are much less than between samples from different hearts; and (4) the ratio of MHC to sarcomeric actin proteins expressed by different ND and DCM hearts remains essentially constant. We conclude that the human ventricle can accommodate a substantial imbalance between sarcomeric MHC and actin mRNA levels while maintaining a constant ratio of their corresponding proteins.

Actins↗
PubMed1997

Plasma clearance of cholyl-lysyl-fluorescein: a pilot study in humans.

BACKGROUND/AIMS: Cholyl-lysyl-fluorescein is a fluorescent analogue of the natural bile acid, cholyl glycine. In vivo and in vitro studies showed that this analogue has many biological characteristics similar to cholyl glycine. In this study we analysed cholyl-lysyl-fluorescein plasma clearance in six healthy volunteers as a potential quantitative liver function test. METHODS: The compound in water for injection was administered as an i.v. bolus in the dose of 0.02 mg/kg b.w. RESULTS: The plasma elimination curve showed rapid, intermediate and slow phases of clearance. Half-life (T1/2 time) for the first (t1/2 1st phase), second (t1/2 2nd phase) and third (t1/2 3rd phase) phases of elimination was 1.7+/-0.9 min, 6.7+/-1.6 min and 68+/-17 min, respectively. Ninety-minute plasma retention (% dose/l plasma) was 2.2%. Cholyl-lysyl-fluorescein volume of distribution and residual fluorescence after 60 min were similar to the data obtained by others for natural or radiolabelled bile acids. In five out of six healthy volunteers a 25-fold higher dose of cholyl-lysyl-fluorescein (0.5 mg/kg b.w.) was injected to estimate the safety margins of the compound. This dose was eliminated at a disappearance rate similar to that of the dose of 0.02 mg/kg b.w. and did not cause any adverse reactions. Serum liver tests measured before and after injection did not change significantly. CONCLUSIONS: This study showed that cholyl-lysyl-fluorescein clearance is similar to the clearance of endogenous natural bile acids and may potentially offer a new, dynamic test of liver function.

Adult↗
PubMed1997

Heart failure--outlooks and strategies for treatment.

The outlook in heart failure patients with a dilated cardiomyopathy has improved dramatically over the past ten years. The availability of many excellent drugs apart from angiotensin II converting enzyme inhibitors (ACEI) has contributed to this. The best current survival rates reported are, however, in association with deliberate optimisation of haemodynamic parameters and incorporation of functional testing to monitor disease progression. These practises could well be adopted more widely in Australia and New Zealand. Surgical options for heart failure continue to expand, but apart from heart transplantation, remain somewhat experimental.

Adrenergic beta-Antagonists↗
PubMed1996

Different electrophoretic techniques produce conflicting data in the analysis of myocardial samples from dilated cardiomyopathy patients: protein levels do not necessarily reflect mRNA levels.

A variety of electrophoretic techniques were used to search for potential causes of human dilated cardiomyopathy (DCM). Northern blots were used to quantify alpha-cardiac and alpha-skeletal muscle actins, and beta-myosin heavy chain mRNAs which are the predominant expressed isoform species. We found a wide range of mRNA levels expressed in both DCM and nondiseased (ND) samples of left ventricles. However, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) gels of the same heart samples revealed a stable and constant ratio of actin and myosin. Dystrophin deficiency might account for the DCM symptoms and so dystrophin levels of DCM and ND samples were evaluated using Western blots probed with monoclonal antibodies for the N-, C- and mid-rod portions of this protein. We found that dystrophin levels were constant in all 29 DCM and 5 ND samples suggesting that dystrophin deficiency is probably not a contributing cause. We explored the possibility that terminal failure may be due to an apoptotic-like event in the cardiomyocytes. Zymograms of DCM and ND samples revealed a significant increase in DNase I activity in the DCM group compared to the ND samples. These data raise the possibility that end-stage failure may be associated with apoptosis.

Actins↗
PubMed1996

Elevated DNase I levels in human idiopathic dilated cardiomyopathy: an indicator of apoptosis?

This is the first report to determine deoxyribonuclease I (DNase I) levels in the human myocardium and the first to demonstrate an increased DNase I level associated with end-stage heart failure due to idiopathic dilated cardiomyopathy (IDCM) compared to non-diseased heart samples. Left ventricular samples were obtained following transplantation from failing hearts of 13 patients diagnosed with IDCM and from four unused donor hearts. Using a zymogram technique, we show that the DNase I levels of the IDCM heart samples were significantly elevated (range 0.65-2.75 pg DNase I/microgram protein, mean +/- S.E. of 1.69 +/- 0.22 pg/micrograms) compared to four non-diseased, donor heart samples (range 0.12-0.35 pg/microgram protein, mean +/- S.E. of 0.22 +/- 0.05 pg/microgram). The DNase I extracted from heart tissue was characterized by: (1) a co-migration with bovine pancreatic DNase I; (2) a pH dependence consistent with DNase I; (3) a dependence of its activity on both Ca2+ and Mg2+ and an inhibition by Zn2+; and (4) an inhibition of its activity in the presence of monomeric rabbit skeletal muscle actin. The elevated DNase I levels associated with heart failure due to IDCM suggests that apoptosis may be implicated in pathophysiology of this disorder.

Actins↗
PubMed1996

Activation of tamoxifen and its metabolite alpha-hydroxytamoxifen to DNA-binding products: comparisons between human, rat and mouse hepatocytes.

The metabolic activation of tamoxifen and its metabolite alpha-hydroxytamoxifen in primary cultures of rat, mouse and human hepatocytes has been compared. The extent of formation of DNA adducts in these cells was measured by 32P-postlabelling, using either nuclease P1 digestion or sorbent extraction of DNA digests to enhance the sensitivity of the assay. DNA adducts were readily detected in rat hepatocytes treated with 1 or 10 microM tamoxifen (mean levels 18.2 and 89.8 adducts/10(8) nucleotides respectively). Similar levels of adducts were formed by mouse hepatocytes (15.0 +/- 1.8 adducts/10(8) nucleotides, 10 microM tamoxifen). However DNA adducts were not detected in tamoxifen-treated human hepatocytes with a detection limit for the assay of 4 adducts/10(10) nucleotides. Treatment of rat cells with alpha-hydroxytamoxifen resulted in 15- to 63-fold higher levels of adducts than with comparable concentrations of tamoxifen. A similar level of adducts was also seen in mouse hepatocytes treated with alpha-hydroxytamoxifen at the 1 microM concentration (173.9 +/- 4.1 adducts/10(8) nucleotides). Treatment of human cells with alpha-hydroxytamoxifen resulted in DNA adduct formation at levels (1.94 +/- 0.89 and 18.9 +/- 17.9 adducts/10(8) nucleotides at 1 and 10 microM respectively) approximately 300-fold lower than those in rat hepatocytes. The presence of alpha-hydroxytamoxifen in the culture medium from experiments where cells were incubated with tamoxifen was monitored by mass spectrometry. Concentrations were found to be approximately 50-fold lower in the medium from human hepatocytes than from rat and mouse hepatocytes.

Adolescent↗
PubMed1996

Clinical heart transplantation. Total lymphoid irradiation for resistant rejection after heart transplantation: only moderate success medium-term.

Total lymphoid irradiation (640 cGy) was given to 19 heart and 1 heart-lung recipients on maintenance triple therapy at a mean of 4.9 +/- 4 months after transplantation (range 46 to 519 days). Mean number of treated rejection episodes before, during, and after total lymphoid irradiation was 6.4 +/- 1.7, 0.8 +/- 1.2, and 1.2 +/- 1.3 episodes per patient, respectively. During total lymphoid irradiation, 37% had at least one episode of rejection requiring treatment; after total lymphoid irradiation, 42% had no further rejection episodes, 21% had one further episode, and 37% had 2 or more episodes. Metastatic squamous cell carcinoma in one patient and coronary artery disease in three of five patients studied to date is of concern and requires longer follow-up.

Adult↗
PubMed1995

Ketoconazole to reduce the need for cyclosporine after cardiac transplantation.

BACKGROUND: Because ketoconazole can markedly reduce the need for cyclosporine and because it also has antimicrobial properties, it may offer benefits in the treatment of patients after cardiac transplantation. METHODS: We randomly assigned 43 patients at the time of cardiac transplantation to receive ketoconazole (200 mg per day) (23 patients) or no ketoconazole (20 patients). The main end points were the dose of cyclosporine required and the incidence of cardiac rejection and infection. RESULTS: Ketoconazole reduced the dose of cyclosporine needed to maintain target levels by 62 percent at one week and by 80 percent at one year. The cost savings per patient (in U.S. dollars, inclusive of the cost of ketoconazole) was about $5,200 in the first year and about $3,920 in each subsequent year. The mean (+/- SD) rate of rejection in the first month was lower in the ketoconazole group than in the controls (4.2 +/- 0.8 vs 5.7 +/- 1.0 episodes per 100 patient-days, P < 0.001), and the average number of days to the first rejection was higher (30 +/- 29 vs. 15 +/- 8, P = 0.03). In the first year, 22 percent of the ketoconazole group required cytolytic therapy, as compared with 35 percent of the controls, and 9 percent of the ketoconazole group required total lymphoid irradiation, as compared with 15 percent of the controls (P = 0.07). The incidence of infection was lower in ketoconazole-treated patients than in controls in the second month (1.4 +/- 0.5 vs. 2.8 +/- 0.7 episodes per 100 patient-days, P < 0.001) and in the third month (0.8 +/- 0.3 vs. 2.3 +/- 0.6 episodes per 100 patient days, P < 0.001). Transient, asymptomatic cholestasis was observed in the ketoconazole group. CONCLUSIONS: After cardiac transplantation, ketoconazole greatly reduced the need for cyclosporine, resulting in substantial cost savings. Ketoconazole also reduced the rates of rejection and infection, without persistent toxic effects. We now use ketoconazole routinely in cardiac-transplant recipients.

Actuarial Analysis↗
PubMed1994

Mechanisms of rapid bone loss following cardiac transplantation.

Rapid bone loss after orthoptic cardiac transplantation (OHTX) is a major problem; however, the mechanisms are poorly understood. To investigate these mechanisms we measured biochemical and hormonal indices of bone turnover serially in 25 patients (21 men, 4 women) after OHTX. Serum osteocalcin was reduced immediately post-OHTX (2.2 +/- 0.5 ng/ml) but rose significantly by 6 and 12 months (14.1 +/- 2.5 and 15.7 +/- 2.2 respectively). Bone resorption indices (urinary hydroxyproline/creatinine and calcium/creatinine ratios) were increased immediately post-OHTX but fell by 6 months. Serum testosterone was reduced in males but recovered towards normal values by 6-12 months. Regression analysis showed lumbar bone loss was predicted independently by the change in both serum osteocalcin and testosterone. The data suggest that bone loss post-OHTX is due to a combination of accelerated turnover and hypogonadism.

Absorptiometry, Photon↗
PubMed1993

Myosin light chain gene expression associated with disease states of the human heart.

During development of the human heart, the atrial isoform of alkali myosin light chain (MLC1A) is expressed in the ventricle. With maturation of the heart, MLC1A expression is completely replaced by that of the adult ventricular myosin light chain, MLC1V. We have evaluated the re-expression of MLC1A as a marker of different disease states of the human ventricle. RNA was isolated from the ventricles of patients with idiopathic dilated cardiomyopathy (CM) and severe congenital cardiac defects (CCD). Northern blot analysis was used to measure the mRNA levels of MLC1A and MLC1V in these samples. As a control, the level of regulatory MLC2V mRNA was also measured. We find that the level of MLC2V mRNA per microgram total ventricular RNA is very similar in CM, CCD and normal human samples. In contrast, we find that MLC1V mRNA levels tend to be reduced in both CM and CCD samples. In the case of the CCD samples, this apparent drop in MLC1V is compensated by expression of the developmental MLC1A isoform. However, in CM patients in end-stage failure, expression of MLC1A is barely detectable. The expression of MLC1A in CCD samples may reflect an adaptive mechanism in response to cardiac overload. The failure to detect substantial MLC1A expression in the CM samples may reflect the failure of such an adaptive mechanism.

Adult↗