A computerized bioskills system for surgical skills training in total knee replacement.

Although all agree that the results of total knee replacement (TKR) are primarily determined by surgical skill, there are few satisfactory alternatives to the 'apprenticeship' model of surgical training. A system capable of evaluating errors of instrument alignment in TKR has been developed and demonstrated. This system also makes it possible quantitatively to assess the source of errors in final component position and limb alignment. This study demonstrates the use of a computer-based system to analyse the surgical skills in TKR through detailed quantitative analysis of the technical accuracy of each step of the procedure. Twelve surgeons implanted a posterior-stabilized TKR in 12 fresh cadavers using the same set of surgical instruments. During each procedure, the position and orientation of the femur, tibia, each surgical instrument, and the trial components were measured with an infrared coordinate measurement system. Through analysis of these data, the sources and relative magnitudes of errors in position and alignment of each instrument were determined, as well as its contribution to the final limb alignment, component positioning and ligament balance. Perfect balancing of the flexion and extension gaps was uncommon (0/15). Under standardized loading, the opening of the joint laterally exceeded the opening medially by an average of approximately 4 mm in both extension (4.1 +/- 2.1 mm) and flexion (3.8 +/- 3.4 mm). In addition, the overall separation of the femur and the tibia was greater in flexion than extension by an average of 4.6 mm. The most significant errors occurred in locating the anterior/posterior position of the entry point in the distal femur (SD = 8.4 mm) and the correct rotational alignment of the tibial tray (SD = 13.2 degrees). On a case-by-case basis, the relative contributions of errors in individual instrument alignments to the final limb alignment and soft tissue balancing were identified. The results indicate that discrete steps in the surgical procedure make the largest contributions to the ultimate alignment and laxity of the prosthetic knee. Utilization of this method of analysis and feedback in orthopaedic training is expected rapidly to enhance surgical skills without the risks of patient exposure.

Hepatocyte transplantation as a bridge to orthotopic liver transplantation in terminal liver failure.

The limited donor organ supply has led to several bridging techniques to sustain patients with acute and subacute liver failure. We report here the prospective, controlled trial of transplanted isolated fresh and cryopreserved human hepatocytes as a bridge to orthotopic liver transplantation. Five hepatocyte transplant recipients with grade IV encephalopathy and multisystem organ failure and four patients of equal illness severity due to liver failure were studied. Medical therapy resulted in a significant (P<0.05), but not normal, fall in blood ammonia, and a significant (P<0.02) resolving biochemical marker of liver injury that did not improve cardiovascular or cerebral stability; this lead to death within 3 days in all control patients. The five hepatocyte-treated patients maintained normal cerebral perfusion and cardiac stability, with withdrawal of medical support for 2 to 10 days before orthotopic liver transplantation. Biochemical evidence of liver injury improved significantly (P=0.004) and blood ammonia levels decreased significantly (P=0.0005) to normal levels in the hepatocyte-treated patients. Three of five patients who successfully bridged to whole liver allograft transplant are alive, home, and normal with more than 20 months of follow-up. No infections or embolic or pulmonary complications resulted from intra-arterial splenic hepatocyte infusion. Specific antiprotease production in a patients with genetically deficient alpha-1-antitrypsin disease, and immunohistochemical and electron microscopic evidence of splenic "hepatization" are presented as evidence of the viability of hepatocyte splenic seeding. In conclusion, splenic transplantation of differentiated adult hepatocytes can control hyper-ammonemia, correct genetic defects in liver function, and bridge life to orthotopic liver transplantation in human liver failure.

Usefulness of low dose guanfacine, once a day, for 24-hour control of essential hypertension.

The 24-hour duration of the antihypertensive effect of guanfacine, a centrally acting alpha 2-adrenoceptor agonist administered once a day, was demonstrated in a 12-week, multicenter, double-blind, placebo-controlled study. Two hundred and forty-nine patients who remained mildly to moderately hypertensive following a 5-week period, during which they had been weaned from previous antihypertensive medications and stabilized on 25-mg chlorthalidone taken once a day, were involved. Of the 249 patients, 126 received guanfacine as a step-2 agent and 123 received placebo. Both groups were further subdivided so that blood pressure (BP) measurements were determined either 12 or 24 hours after dosing. The initial dose of guanfacine was 1 mg/day, which could be raised 1 mg at 2-week intervals to a maximum daily dose of 3 mg/day at the discretion of each investigator. The daily dose could also be lowered by 1 mg at 2-week intervals, depending on patient response. The mean 24-hour reductions with guanfacine in sitting diastolic BP (-11 mm Hg), systolic BP (-14 mm Hg) and mean arterial pressure (-12 mm Hg) were statistically significant (p less than 0.01) compared with the reductions in BP with placebo. Heart rate also decreased with guanfacine, but no clinically relevant bradycardia (less than 60 beats/min) was observed. Dry mouth (47%), constipation (16%), fatigue (12%) and drowsiness (4%) were the most frequently reported side effects. The highly acceptable side-effects profile of guanfacine was also indicated by the small percentage of patients (7%) who prematurely left the study because of adverse reactions.

A simple method for the isolation and culture of epithelial and stromal cells from benign and neoplastic prostates.

OBJECTIVES: Current primary prostate cell culture techniques use an overnight digestion or extensive media preparation. In this report, we describe a method for the culture of benign and neoplastic cells from human prostatectomy specimens that is rapid and contains no undefined factors in the medium. METHODS: Characterization of the human cultured prostate cells was performed using immunohistochemical methods and monoclonal antibodies AE1/AE3 and cytokeratin 8, as well as monoclonal antibodies against prostate-specific antigen (PSA). Polymerase chain reaction was used to measure the exclusive epithelial and stromal cell products, c-met and hepatocyte growth factor (HGF), respectively. Electron microscopy was performed to assess the cell junctions and morphologic features of epithelial cells. Optimum cell growth in different media was tested using a cell replication assay. RESULTS: Microscopic evidence revealed that the cells demonstrate typical epithelial morphology, with polyhedral cells forming tight junctions in a continuous monolayer. Desmosomes were present in electron micrographs of epithelial cells. The cultured epithelial cells described in this report also demonstrate positive cytokeratin staining. The epithelial cells reacted positively with PSA antibody, indicating that the cells retain their secretory role in cell culture for a limited period. Epithelial cells expressed the HGF receptor, c-met; stromal cells secreted HGF. Insulin, transferrin, and selenium increased the growth of cells in the chemically defined media, compared with minimum essential media (MEM) and Ham's F12. CONCLUSIONS: In summary, essentially pure cultures of prostate stromal or epithelial cells have been established using simple isolation and culture methods. These cells will be useful for the investigation of related growth factors, such as insulin-like growth factor I and insulin-like growth factor II, and in understanding the basis for stromal-epithelial cell interactions.

Brief report: validation of a system for automated measurement of knee laxity.

OBJECTIVE: To determine the accuracy and repeatability of an automated quantitative fluoroscopic imaging system for measuring knee laxity. DESIGN: Cadaveric validation study. BACKGROUND: Current methods of measuring anterior-posterior laxity lack sufficient accuracy and repeatability. A commercially developed fluoroscopic software package, capable of measuring laxity, required validation. METHODS: Five human cadaveric knees were used. A constant force of 130 N was applied anteriorly and posteriorly in turn to the tibia of each knee with the femur fixed in 30 degrees and 90 degrees of flexion. Quantitative fluoroscopic measurements of anterior-posterior laxity were determined using image analysis software. Fluoroscopic results were compared to the true anterior-posterior displacements of the tibia, which were simultaneously recorded using linear transducers directly attached to the cadaveric specimens. RESULTS: The quantitative fluoroscopic method underestimated laxity by an average of 0.40 mm with a root mean square error of 0.49 mm. The 95% confidence intervals for anterior and posterior laxity error were calculated to be -0.99 to 0.25 mm and -0.89 to 0.03 mm, respectively, where a negative error represents an underestimation. CONCLUSIONS: The quantitative fluoroscopic method offers a dramatic improvement in accuracy over current laxity measurement techniques and acceptable repeatability for assessing ligament damage. RELEVANCE: The considerably more accurate, validated measurement system of this study could improve ligament assessment and diagnosis, and the recognition of injuries otherwise undetected with current methods.

Making minimally invasive THR safe: conclusions from biomechanical simulation and analysis.

The use of smaller surgical incisions has become popularized for total hip arthroplasty (THR) because of the potential benefits of shorter recovery and improved cosmetic appearance. However, an increased incidence of serious complications has been reported. To minimize the risks of minimally invasive approaches to THR, we have developed an experimental approach which enables us to evaluate risk factors in these procedures through cadaveric simulations performed within the laboratory. During cadaveric hip replacement procedures performed via posterior and antero-lateral mini-incisions, pressures developed between the wound edges and the retractors were approximately double those recorded during conventional hip replacement using Charnley retractors (p < 0.01). In MIS procedures performed via the dual-incision approach, lack of direct visualisation of the proximal femur led to misalignment of broaches and implants with increased risk of cortical fracture during canal preparation and implant insertion. Cadaveric simulation of surgical procedures allows surgeons to measure variables affecting the technical success of surgery and to master new procedures without placing patients at risk.

Investigation of the cooperative effects of transforming growth factor alpha and c-myc overexpression in rat liver epithelial cells.

Overexpression of both transforming growth factor (TGF)-alpha and c-myc is consistently reported in hepatic tumors. We transfected rat liver epithelial cells (RLECs) with expression vectors for TGF-alpha, c-myc, or both and analyzed the morphology, biological properties, and tumorigenicity of clones that overexpressed these genes. The transfectants were morphologically indistinguishable from the parental RLECs, but the overexpression of TGF-alpha resulted in changes in growth properties and an enhanced response to the mitogenic effects of hepatocyte growth factor. The concomitant overexpression of c-myc decreased growth factor requirements of the TGF-alpha lc-myc clones compared with RLEC and TGF-alpha clones. The TGF-alpha and TGF-alpha lc-myc clones were tumorigenic in nude mice at frequencies of 27% and 53%, respectively, indicating that the genes cooperate in malignant transformation. However, the untransformed nature and low tumorigenicity of the transfectants suggest that transformation depends on other cellular events in addition to the overexpression of TGF-alpha or c-myc. Characterization of tumor cell lines showed that in contrast to the transfectants, the tumor clones were morphologically transformed, capable of autonomous growth and anchorage-independent growth, and aggressively tumorigenic with a frequency of 100%. Clearly, the tumor cells differed from the transfectants and had undergone biological or genetic alterations (or both) as a consequence of the overexpression of TGF-alpha or c-myc. Our data suggest that the overexpression of TGF-alpha leads to enhanced responsiveness to hepatocyte growth factor, whereas the concomitant overexpression of c-myc confers growth-factor independence, providing a potential explanation of the mechanisms by which the overexpression of these genes results in transformation.

Phenotypic variability in induction of P-glycoprotein mRNA by aromatic hydrocarbons in primary human hepatocytes.

To determine whether human liver responds to treatment with aromatic hydrocarbons (AHs) with induction of the multidrug resistance (mdr) gene product P-glycoprotein and whether AH induction of mdr involves the Ah receptor, we compared induction of mdr mRNA with induction of cytochrome P450 (CYP)1A1 mRNA in AH-treated cultures of primary human hepatocytes. Hepatocytes from all 15 individuals tested responded to treatment with 3-methylcholanthrene (MC) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with induction of CYP1A1 mRNA. However, only 62% and 55% of the preparations responded to treatment with MC and TCDD, respectively, with induction of mdr mRNA. Indeed, in some individuals mdr mRNA was suppressed by MC and TCDD despite robust CYP1A1 induction. These studies provide the first evidence that not only does individual variation in mdr induction by AH exist but that AHs regulate mdr in humans by a novel mechanism distinguishable from the classical Ah receptor pathway. The dramatic variability in AH induction of mdr may be a predictive risk factor that will help to identify an individual's risk of AH-associated toxicities.

Expression and inducibility of the human bilirubin UDP-glucuronosyltransferase UGT1A1 in liver and cultured primary hepatocytes: evidence for both genetic and environmental influences.

In Crigler-Najjar type II patients and, recently, in Crigler-Najjar type I patients treated with human hepatocyte cell therapy, phenobarbital has been used for reducing the serum bilirubin load. Its effect is attributed to induction of the enzyme required for hepatic bilirubin elimination, UDP-glucuronosyltransferase, UGT1A1. This study investigated the expression and inducibility of UGT1A1 in human donor livers and their corresponding primary hepatocyte cultures. Immunoblot analysis using a specific antibody directed against the amino terminal of the human UGT1A1 isoform showed that 5 hepatocyte donors exhibited a >50-fold difference in UGT1A1 level. UGT1A1 protein level correlated strongly with both liver microsomal bilirubin UGT activity and liver UGT1A1 mRNA level (r(2) =.82 and.72, respectively). Of the 4 patients with the lowest UGT1A1 levels, 3 were homozygotes for the UGT1A1 promoter variant sequence associated with Gilbert's syndrome, and the fourth was a heterozygote. The 3 donors with the highest levels had a history of phenytoin exposure. Hepatocytes isolated from the phenytoin-exposed donors exhibited marked declines in UGT1A1 mRNA levels during culturing. Induction studies using hepatocytes treated for 48 hours with phenobarbital (2 mmol/L), oltipraz (50 micromol/L), or 3-methylcholanthrene (2.5 micromol/L) revealed UGT1A1-inducing effects of phenobarbital, oltipraz, and, in particular, 3-methylcholanthrene. Our data suggest that both genetic and environmental factors play an important role in the marked interindividual variability in UGT1A1 expression. An understanding of these mechanisms could lead to advances in the pharmacological therapy of life-threatening unconjugated hyperbilirubinemia.

Time course of recovery of adrenal function in children treated for leukemia.

OBJECTIVE: Many protocols for treating children with early B-cell lineage acute lymphoblastic leukemia use 28 consecutive days of high-dose glucocorticoids during induction therapy. We prospectively studied the effects of this therapy on adrenal function. STUDY DESIGN: Ten children with early B-cell lineage acute lymphoblastic leukemia were evaluated by cosyntropin (corticotropin (1-24)) stimulation testing before initiation of dexamethasone therapy and every 4 weeks thereafter until adrenal function returned to normal. RESULTS: All 10 patients had normal adrenal function before dexamethasone treatment and insufficient adrenal responses 24 hours after completing therapy. Each child felt ill for 2 to 4 weeks after completing therapy. Although 7 patients recovered normal adrenal function after 4 weeks, 3 patients did not have normal adrenal function until 8 weeks after discontinuing therapy. Statistically significant differences in both basal and corticotropin-stimulated cortisol levels were noted when comparing tests performed at baseline, 24 hours after completing therapy, and 4 weeks after completing therapy. CONCLUSION: High-dose dexamethasone therapy, a standard treatment for early B-cell acute lymphoblastic leukemia, can cause adrenal insufficiency lasting more than 4 weeks after cessation of treatment. This problem might be avoided by tapering doses of glucocorticoids and providing supplemental glucocorticoids during periods of increased stress.

Regulation of human liver cytochromes P-450 in family 3A in primary and continuous culture of human hepatocytes.

The cytochrome P-450 3A gene family comprises the dominant forms of cytochrome P-450 found in human liver. We examined as a possible useful system for studying the regulation of cytochrome P-450 3A under controlled conditions in vitro, primary monolayer cultures of human hepatocytes and compared the results with those obtained from the study of cytochrome P-450 3A in the human hepatoblastoma cell line HepG2 or in the human hepatocellular carcinoma cell line TONG/HCC. Using 3A antibodies, 3A cDNAs and 3A3, 3A4, 3A5 and 3A7 isozyme-specific oligonucleotides as probes, we determined that primary human hepatocyte cultures routinely expressed a 3A3/4* immunoreactive protein and 3A mRNA. These gene products were well maintained for many days and were induced by treatment of the cultures with dexamethasone, phenobarbital, macrolide antibiotics, the HMG CoA reductase inhibitor lovastatin or an antifungal agent, clotrimazole. Of six donor livers examined, only two contained mRNA or protein for 3A5, a form found in only a few adult human subjects. In cultures prepared from one of these two livers, 3A5 mRNA was detectable for several days. In cultures of hepatocytes from the remaining four human livers that did not contain 3A5 mRNA or protein, we detected neither spontaneous nor inducible 3A5 proteins or mRNAs. HepG2 cells contained only 3A7 protein, a form found in human fetal liver, even after treatment with inducers. treatment of HepG2 cells with dexamethasone, macrolide antibiotics, phenobarbital and phenobarbital-like inducers or lovastatin produced dose-dependent induction of 3A7 mRNA and 3A7 immunoreactive protein. TONG/HCC cells contained 3A3, 3A4 and 3A5 mRNAs, but only 3A5 immunoreactive protein could be detected.(ABSTRACT TRUNCATED AT 250 WORDS)