Alterations in p53 and p16INK4 expression and telomere length during spontaneous immortalization of Li-Fraumeni syndrome fibroblasts

Normal cells have a strictly limited growth potential and senesce after a defined number of population doublings (PDs). In contrast, tumor cells often exhibit an apparently unlimited proliferative potential and are termed immortalized. Although spontaneous immortalization of normal human cells in vitro is an extremely rare event, we observed this in fibroblasts from an affected member of a Li-Fraumeni syndrome kindred. The fibroblasts were heterozygous for a p53 mutation and underwent senescence as expected at PD 40. In four separate senescent cultures (A to D), there were cells that eventually recommenced proliferation. This was associated with aneuploidy in all four cultures and either loss (cultures A, C, and D) or mutation (culture B) of the wild-type (wt) p53 allele. Loss of wt p53 function was insufficient for immortalization, since cultures A, B, and D subsequently entered crisis from which they did not escape. Culture C has continued proliferating beyond 400 PDs and thus appears to be immortalized. In contrast to the other cultures, the immortalized cells have no detectable p16INK4 protein. A culture that had a limited extension of proliferative potential exhibited a progressive decrease in telomere length with increasing PD. In the culture that subsequently became immortalized, the same trend occurred until PD 73, after which there was a significant increase in the amount of telomeric DNA, despite the absence of telomerase activity. Immortalization of these cells thus appears to be associated with loss of wt p53 and p16INK4 expression and a novel mechanism for the elongation of telomeres.

A novel human cDNA highly homologous to the fish hormone stanniocalcin

Stanniocalcin is a glycoprotein hormone previously considered present only in bony fish where it is secreted by the corpuscles of Stannius, endocrine organs involved in Ca2+ homeostasis. In fish, stanniocalcin was thought to be an adaptation for Ca2+ regulation in aquatic environments, and its effects include inhibition of gill Ca2+ transport. We have obtained a human cDNA clone coding for a protein highly homologous to fish stanniocalcin. The mRNA is expressed in many human tissues, with the highest levels in ovary, prostate and thyroid. In vitro human cell culture studies show that the mRNA is positively regulated by extracellular Ca2+ in the medium. We conclude that a human protein similar to the fish hormone is expressed in multiple tissues rather than by a specialized endocrine organ.

Relief of left ventricular outflow tract obstruction following inadvertent left ventricular apical pacing in a patient with hypertrophic cardiomyopathy

Dual chamber (DDD) pacing improves symptoms and relieves left ventricular (LV) outflow obstruction in hypertrophic cardiomyopathy. The ventricular lead is usually positioned at the right ventricular apex (RVA). We report a patient in whom the ventricular lead had inadvertently penetrated the septum, resulting in DDD pacing from the LV apex. However, after 3 months, obstruction was reduced and symptoms were improved. Pacing from LV apex and RVA resulted in comparable hemodynamic improvement. This case suggests that the asynchronous wave of septal contraction, originating from the apex, irrespective of ventricular site, accounts for the reduction in LV outflow obstruction.

Successful use of transesophageal echocardiography during extracorporeal membrane oxygenation in infants after cardiac operations

We report the use of transesophageal echocardiography in infants after cardiac operations while supported on extracorporeal membrane oxygenation. In all patients transesophageal echocardiography provided valuable information when standard transthoracic echocardiographic evaluation was limited by poor acoustic windows. This report describes the application of transesophageal echocardiography during extracorporeal membrane oxygenation after cardiac operations.

Cerebrovascular accidents following the Fontan operation

The Fontan operation is one of the most common cardiac operations for children with congenital heart disease beyond the first year of age. Although the surgical mortality of this procedure has improved over the past 2 decades, the neurologic outcome in this population is not well described. We performed a retrospective review of 645 patients who underwent the Fontan procedure at Children's Hospital in Boston over the 15-year period between August, 1978 and July, 1993, to describe the incidence of postoperative cerebrovascular accidents or strokes among survivors. We identified 17 patients (2.6%) who suffered a stroke following the Fontan operation. The risk period for stroke in our population extended from the first postoperative day to 32 months after the Fontan procedure. The pre-, intra-, and postoperative clinical features of these patients are described.

Expression of a novel integrin beta 1 chain epitope and anti-beta 1 antibody-mediated enhancement of fibronectin binding are dependent on the stage of T cell differentiation

Beta 1 integrins are a family of alpha beta heterodimers that serve as cell surface receptors for extracellular matrix proteins. We demonstrate that the anti-mouse integrin beta 1 chain mAb KMI6 selectively recognizes a beta 1 epitope that is constitutively expressed by certain immature thymocytes and is induced only slightly on mature thymocytes and peripheral T cells by activation with Con A. Because virtually all cells examined expressed beta 1 integrins on their surface, expression of the KMI6 epitope is T cell differentiation stage specific. Most CD3-4-8- thymocytes were KMI6+, with the lowest level of staining observed on the earliest CD44+IL-2R- cells within this subset. Expression was down-regulated during the CD3-4-8- to CD3-4-8+ transition, and lost by the CD4+8+ stage. Mature single positive thymocytes and resting peripheral T cells were also KMI6-. In contrast with the loss of the epitope before TCR expression by other thymocytes, most CD3+4-8- and certain CD8+ gamma delta TCR+ thymocytes were KMI6+ Addition of KMI6 to cell adhesion assays enhanced CD4-8- thymocyte, but not activated mature thymocyte or peripheral T cell, binding to fibronectin (via alpha 4 beta 1 and alpha 5 beta 1), whereas laminin binding (via alpha 6 beta 1) was unaffected. These properties distinguish the KMI6 epitope from other epitopes involved in beta 1 integrin activation in mice and other species. The unique selectivity of KMI6 recognition of beta 1 integrins, and its selective enhancement of ligand binding suggest that beta 1 integrin structure and factors that regulate beta 1 integrin binding are correlated with the stage of T cell differentiation.

Expression of a novel integrin beta 1 chain epitope and anti-beta 1 antibody-mediated enhancement of fibronectin binding are dependent on the stage of T cell differentiation

Beta 1 integrins are a family of alpha beta heterodimers that serve as cell surface receptors for extracellular matrix proteins. We demonstrate that the anti-mouse integrin beta 1 chain mAb KMI6 selectively recognizes a beta 1 epitope that is constitutively expressed by certain immature thymocytes and is induced only slightly on mature thymocytes and peripheral T cells by activation with Con A. Because virtually all cells examined expressed beta 1 integrins on their surface, expression of the KMI6 epitope is T cell differentiation stage specific. Most CD3-4-8- thymocytes were KMI6+, with the lowest level of staining observed on the earliest CD44+IL-2R- cells within this subset. Expression was down-regulated during the CD3-4-8- to CD3-4-8+ transition, and lost by the CD4+8+ stage. Mature single positive thymocytes and resting peripheral T cells were also KMI6-. In contrast with the loss of the epitope before TCR expression by other thymocytes, most CD3+4-8- and certain CD8+ gamma delta TCR+ thymocytes were KMI6+ Addition of KMI6 to cell adhesion assays enhanced CD4-8- thymocyte, but not activated mature thymocyte or peripheral T cell, binding to fibronectin (via alpha 4 beta 1 and alpha 5 beta 1), whereas laminin binding (via alpha 6 beta 1) was unaffected. These properties distinguish the KMI6 epitope from other epitopes involved in beta 1 integrin activation in mice and other species. The unique selectivity of KMI6 recognition of beta 1 integrins, and its selective enhancement of ligand binding suggest that beta 1 integrin structure and factors that regulate beta 1 integrin binding are correlated with the stage of T cell differentiation.

Pulmonary vascular resistance in infants after cardiac surgery: role of carbon dioxide and hydrogen ion

OBJECTIVE

The objective of this study was to describe the effects of altering arterial PCO2 and pH on pulmonary vascular resistance in infants after cardiopulmonary bypass for cardiac surgery.

DESIGN

Prospective study (with each patient as his or her own control).

SETTING

Cardiac intensive care unit in a children's hospital.

PATIENTS

We studied 15 infants (ages ranging from 0.4 to 15.6 months; median 5.7) who were mechanically ventilated during the immediate postoperative period after corrective cardiac surgery.

INTERVENTIONS

The study was designed to have the following three stages: In the baseline stage, the initial postoperative hemodynamic parameters were stabilized and body temperature was normalized. In the hypercarbia stage, with FIO2 at 0.40, the rate of ventilation was decreased to produce an end-tidal CO2 level of > 55 torr (> 7.3 kPa). This stage established a clinical model of increased pulmonary vascular resistance. With the minute ventilation held constant in order to maintain a constant PaCO2, the arterial pH was increased by administration of a 4-mEq/kg iv dose of sodium bicarbonate (sodium bicarbonate stage). Arterial blood gas and hemodynamic determinations were obtained after a 10-min stabilization period at each stage. Drug infusions were not altered during the study period.

MEASUREMENTS AND MAIN RESULTS

In the hypercarbia stage (stage 2), the mean PaCO2 increased from 36 +/- 5 torr (4.8 +/- 0.7 kPa) (at baseline) to 55 +/- 16 torr (7.3 +/- 2.1 kPa) (p < .01). As a result, the mean arterial pH decreased from 7.48 +/- 0.05 to 7.31 +/- 0.03 (p < .01). During this stage, the mean pulmonary arterial pressure increased from 21 +/- 6 to 30 +/- 8 mm Hg (p < .01) but the cardiac index remained unchanged (3.7 +/- 1.2 to 3.8 +/- 1.2 L/min/m2). Pulmonary vascular resistance index increased from 4.1 +/- 2.0 to 6.0 +/- 3.1 U.m2 (p < .01). After the administration of sodium bicarbonate (stage 3), the arterial pH increased to 7.44 +/- 0.06 (p < .05), while the PaCO2 was unchanged. The pulmonary vascular resistance index decreased to 3.1 +/- 1.5 U.m2 (from 6.0 +/- 3.1 U.m2; p < .01) as a result of both a decrease in mean pulmonary arterial pressure (to 26 +/- 6 mm Hg; p < .01) and a concomitant increase in cardiac index to 5.1 +/- 1.6 L/min/m2 (p < .01).

CONCLUSIONS

Increasing the arterial pH by the administration of sodium bicarbonate both lowers the pulmonary arterial pressure and increases the cardiac index, resulting in a decrease in pulmonary vascular resistance. These changes were observed without alteration in PaCO2. Metabolic alkalosis may have a role in the treatment of increased pulmonary vascular resistance in infants after cardiopulmonary bypass for cardiac surgery.

Alpha 3 beta 1 and alpha 6 beta 1 integrins mediate laminin/merosin binding and function as costimulatory molecules for human thymocyte proliferation

Integrins comprise a superfamily of alpha beta heterodimers that serve as cell signaling as well as adhesion molecules. We demonstrate that the alpha 3 beta 1 and alpha 6 beta 1 integrins are laminin/merosin receptors expressed in human thymocytes. By reverse transcriptase-PCR analysis, we determined that the alpha 3A beta 1, but not the alpha 3B beta 1, cytoplasmic structural variant of alpha 3 beta 1 is expressed in thymocytes. In contrast, both alpha 6A beta 1 and alpha 6B beta 1 cytoplasmic structural variants of alpha 6 beta 1 are expressed. A small percentage (10 to 15%) of human thymocytes bind to immobilized laminin, and even fewer (3 to 5%) bind to merosin, the laminin isoform normally present in the thymus. This binding, however, can be increased to 39 to 41% after activation of thymocytes with Mn2+ (or PMA). Binding to either laminin or merosin is completely inhibited by anti-beta 1 mAb or by a mixture of anti-alpha 3 and anti-alpha 6 mAbs, indicating that both alpha 3 beta 1 and alpha 6 beta 1 participate in thymocyte adhesion to the laminin family of extracellular matrix proteins. The protein kinase C inhibitors, calphostin C and staurosporine, inhibit Mn(2+)-enhanced thymocyte binding, suggesting that protein kinase C activity is crucial for the binding. Furthermore, the data indicate that at least two divalent cation binding sites serve to regulate integrin binding activity. Finally, we show that both immobilized laminin and merosin have costimulatory function for anti-CD3-induced thymocyte proliferation, and both anti-alpha 3 and anti-alpha 6 mAbs can block this proliferative response. The cooperative function of alpha 3 beta 1 and alpha 6 beta 1 evidenced in the laminin/merosin binding and proliferation assays suggests that thymocyte-merosin interactions may play an important role in thymic T cell development.

Alpha 3 beta 1 and alpha 6 beta 1 integrins mediate laminin/merosin binding and function as costimulatory molecules for human thymocyte proliferation

Integrins comprise a superfamily of alpha beta heterodimers that serve as cell signaling as well as adhesion molecules. We demonstrate that the alpha 3 beta 1 and alpha 6 beta 1 integrins are laminin/merosin receptors expressed in human thymocytes. By reverse transcriptase-PCR analysis, we determined that the alpha 3A beta 1, but not the alpha 3B beta 1, cytoplasmic structural variant of alpha 3 beta 1 is expressed in thymocytes. In contrast, both alpha 6A beta 1 and alpha 6B beta 1 cytoplasmic structural variants of alpha 6 beta 1 are expressed. A small percentage (10 to 15%) of human thymocytes bind to immobilized laminin, and even fewer (3 to 5%) bind to merosin, the laminin isoform normally present in the thymus. This binding, however, can be increased to 39 to 41% after activation of thymocytes with Mn2+ (or PMA). Binding to either laminin or merosin is completely inhibited by anti-beta 1 mAb or by a mixture of anti-alpha 3 and anti-alpha 6 mAbs, indicating that both alpha 3 beta 1 and alpha 6 beta 1 participate in thymocyte adhesion to the laminin family of extracellular matrix proteins. The protein kinase C inhibitors, calphostin C and staurosporine, inhibit Mn(2+)-enhanced thymocyte binding, suggesting that protein kinase C activity is crucial for the binding. Furthermore, the data indicate that at least two divalent cation binding sites serve to regulate integrin binding activity. Finally, we show that both immobilized laminin and merosin have costimulatory function for anti-CD3-induced thymocyte proliferation, and both anti-alpha 3 and anti-alpha 6 mAbs can block this proliferative response. The cooperative function of alpha 3 beta 1 and alpha 6 beta 1 evidenced in the laminin/merosin binding and proliferation assays suggests that thymocyte-merosin interactions may play an important role in thymic T cell development.

Identification of patients with hypertrophic cardiomyopathy at high risk for sudden death

Patients with hypertrophic cardiomyopathy are at increased risk for sudden death. Recent studies have improved our ability to risk-stratify such patients and have elucidated several potential mechanisms of sudden death and syncope. Certain noninvasive tests, such as signal-averaged electrocardiography and measurements of cardiac autonomic function and QT/QT dispersion, are often abnormal in hypertrophic cardiomyopathy, but are not useful for risk stratification. Myocardial ischemia determined by exercise thallium scintigraphy, however, identifies young patients with hypertrophic cardiomyopathy who are at high risk for cardiac arrest and syncope. Nonsustained ventricular tachycardia on ambulatory Holter monitoring in the absence of symptoms of impaired consciousness is associated with a benign prognosis and is not predictive of sudden death. Conversely, ventricular tachycardia induced at electrophysiologic study identifies adult patients with hypertrophic cardiomyopathy who subsequently experience sudden death. Finally, characterization of the natural history of the genetic defects will increasingly become an integral part of risk evaluation in hypertrophic cardiomyopathy.

kappa Opioid receptor selective affinity labels: electrophilic benzeneacetamides as kappa-selective opioid antagonists

2-(3,4-Dichlorophenyl)-N-methyl-N-[1-(3- or 4-substituted phenyl)-2-(1-pyrrolidinyl)ethyl]-acetamides 3-6 were synthesized as kappa-selective affinity labels and evaluated for opioid activity. In smooth muscle preparations, the non-electrophilic parent compound (+)-S-2 and the affinity labels 3-6 behaved as kappa agonists in that they were potently antagonized by norbinaltorphimine (norBNI). In addition to the high binding affinity and selectivity of the 3-isothiocyanate 3 (DIPPA) to kappa opioid receptors, wash studies have suggested that this involves covalent binding. In the mouse tail-flick assay, the 3- and 4-substituted isomers (3 and 5, respectively) produced long-lasting antagonism of the antinociceptive effect of the kappa opioid agonist, (+/-)-trans-2-(3,4-dichlorophenyl)-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl]acetamide ((+/-)-U50,488). In contrast, the non-electrophilic parent compound (+)-S-2 and the fumaramate derivative 4 were devoid of antagonist activity in the tail-flick assay. At substantially different doses, DIPPA (3) and the 4-isothiocyanate 5 also produced antinociception in the mouse abdominal stretch assay. In addition, DIPPA and the 3-fumaramate methyl ester 4 had improved in vivo kappa-selectivities compared to the unsubstituted parent compound (+)-S-2 and the para-substituted derivative 5. The improved kappa-selectivities of 3 and 4 and the different agonist and antagonist potencies of 3 and 5 may be explained respectively by the existence of multiple kappa agonist binding sites and distinct agonist and antagonist binding sites. In view of the antagonist selectivity and the apparent irreversible binding of DIPPA to kappa receptors, it may serve as a useful pharmacologic or biochemical tool to investigate kappa opioid receptors.

Study of septic shock in the non-human primate: relationship of pathophysiological response to therapy with anti-TNF antibody

Therapy with anti-TNF antibody is reported to be effective in preventing morbidity and mortality in baboons given lethal infusions of Escherichia coli. Treated animals survived, and organ histopathology was absent when antibody was administered early after lethal infusions of E. coli. The present study explored the relationship between antibody dosage, pathophysiology, and survivability from shock. When antibody dose was decreased lungs, kidneys, adrenals, spleen, and liver were injured as shown by increased vascular congestion, hemorrhage, edema, and necrosis of tissues. Survival was also affected. All animals treated with 15 mg/kg antibody survived as reported earlier; less than 60% survived with 7.5 mg/kg; 9% survived with 5.0 mg/kg, and all died with 1.5 mg/kg. Serum concentrations of interleukin-6 (IL-6) increased markedly as dose of antibody decreased. The increases in concentrations of IL-6 were associated with increases in morbidity and mortality following E. coli administration.

Recombinant E. coli-derived tissue factor pathway inhibitor reduces coagulopathic and lethal effects in the baboon gram-negative model of septic shock

Excessive coagulation is a typical response to the vascular injury occurring in gram negative sepsis. This study evaluated the pharmacological effects of the use of a recombinant Escherichia coli derived form of tissue factor pathway inhibitor (ala-TFPI) in a baboon model of septic shock. Several doses of ala-TFPI were administered either 30 or 120 min after the initiation of a lethal intravenous infusion of E. coli into baboons. Treatment at 30 min with either 2.7 or 7.4 mg/kg of ala-TFPI resulted in the same survival rates and attenuation of both the coagulation response and cellular injury, as measured by clinical chemistry. When administration of ala-TFPI was delayed for 120 min, a dose of ala-TFPI protein continued to provide a benefit to survival. Ala-TFPI reduced the drop in mean systemic arterial pressure compared to control baboons in addition to partially attenuating the coagulopathic response. Baboons given ala-TFPI also maintained lower levels of plasma interleukin-6 (IL-6) and thrombin-antithrombin. These results suggest that the site of action of the protein may involve the later stage components of the coagulation and inflammatory pathways.

Constitutive activation of integrin alpha 4 beta 1 defines a unique stage of human thymocyte development

Our understanding of thymocyte development and of the positive and negative selection events involved in shaping the repertoire of mature T lymphocytes has been greatly facilitated by the use of transgenic and gene knockout animals. Much less is known about the factors that control the homing and population of the thymus by T cell precursors and the subsequent migration of developing thymocytes through the thymic architecture. As the integrins represent a candidate group of cell surface receptors that may regulate thymocyte development, we have analyzed the expression and function of alpha 4 beta 1 and alpha 5 beta 1 on human thymocytes. A major portion of double positive (CD4+ CD8+) human thymocytes express alpha 4 beta 1 in a constitutively active form and adhere to fibronectin and vascular cell adhesion molecule 1. alpha 4 beta 1 expression is similar on adherent and nonadherent populations, thus, activity reflects the receptor state and not simple expression. The adherent cells are immature, expressing high levels of CD4/CD8 and low levels of CD3 and CD69. In contrast, nonadherent cells possess the phenotype of thymocytes after positive selection, expressing intermediate levels of CD4 and/or CD8 and high levels of CD3 and CD69. The adherent population fails to respond to activation with anti-CD3 and fibronectin, whereas nonadherents exhibit an alpha 5 beta 1-dependent proliferation. Differential regulation of alpha 4 beta 1 and alpha 5 beta 1 receptors may provide a mechanism controlling cellular traffic, differentiation, and positive selection of thymocytes.

In vitro transformation of Li-Fraumeni syndrome fibroblasts by SV40 large T antigen mutants

Transfection of SV40 early region DNA into normal human diploid fibroblasts (NHDFs) increases their proliferative potential to a limited extent. We have investigated the roles of the SV40 large T antigen (LTAg) regions responsible for binding to the protein products of the retinoblastoma (Rb) and p53 genes in this temporary escape from senescence. Patients encoding LTAg mutants were transfected into NHDFs and into Li-Fraumeni syndrome (LFS) fibroblasts which are heterozygous wild-type (wt)/null-mutant for p53. A LTAg mutated in the p53-binding region (T402DE) had greatly reduced efficiency of focus formation, and a p110Rb-binding mutant was unable to induce any foci. T402DE-induced NHDF foci senesced at the same time as untransfected cells, but the equivalent LFS foci all had increased proliferative potentials, with the greatest increase being seen in clones that lost the wt p53 allele. One LFS clone expressed the T402DE mutant during focus formation, but later lost both the T402DE DNA and the wt p53 allele. We conclude that SV40-induced focus formation in NHDFs requires the LTAg p110Rb-binding region, and is enhanced by loss of normal p53 function. In contrast, increased proliferative potential is primarily due to loss of p53 function.

Management and outcome of low birth weight neonates with congenital heart disease

In 100 consecutive neonates with birth weights < or = 2500 gm (range, 540 to 2500 gm; median, 2200 gm), major congenital heart disease (excluding patent ductus arteriosus, isolated atrial septal defect, and ventricular septal defect) was diagnosed between January 1987 and January 1991; 46 had ductus-dependent lesions. Of the 100 neonates, 30 had genetic aberrations or significant associated congenital anomalies. The four most common cardiac diagnoses were tetralogy of Fallot with or without pulmonary atresia (n = 16); coarctation of the aorta (n = 12); transposition of the great arteries (n = 11); and common atrioventricular canal (n = 11). The hospital survival rate for the entire group of 100 neonates was 70%. The patients were separated into three groups on the basis of the time of intervention. Group 1 (early intervention) included 62 infants. These neonates (including 31 with ductus-dependent lesions) had surgical or catheter intervention during the initial hospitalization (median age, 9 days), all at weights < or = 2500 gm. The hospital survival rate was 81% (50/62); survival rates for palliation (78%, 18/23) and for correction (82%, 32/39) were similar. There were 26 neonates in group 2 (late intervention). These neonates did not have surgical intervention during the initial hospitalization. All were managed medically; survivors were discharged and had surgical procedures later (at a median age of 4.3 months). Six neonates (23%) died during medical management; all 20 survivors returned and had surgical procedures, with 90% survival. Overall survival rate for this group was 69% (18/26). The remaining 12 patients (group 3) had complicating features that precluded intervention; none survived. On the basis of these results, we conclude that early intervention, even with corrective surgery, can be performed in low birth weight neonates with an acceptable mortality rate. Prolonged medical therapy to achieve further weight gain did not appear to improve the survival rate.

Assignment of two alpha 2 adrenoceptor subtype genes to murine chromosomes

Subtype-specific probes to the murine homologs of the human ADRA2B and ADRA2C genes were prepared by PCR amplification and used to map these two genes to mouse chromosomes 2 and 5, respectively. Both genes mapped in regions of mouse chromosomes consistent with their map location in humans. These mapping results provide additional insights into the linkage relationships among members of this important gene family.

Retrospective description and experimental reconstitution of three different responses of the baboon to lethal E. coli

This paper is divided into a retrospective descriptive section in which we report on three distinctly different and spontaneous responses of the baboon to LD100 Eschericia coli observed over the last 6 years. This section is followed by an experimental section in which we reproduce the immediate and delayed responses based on hypothetical mechanisms. In the descriptive section, we arbitrarily divided all the non-survivor animals on which we had sufficient data into three groups based on duration of survival (i.e., 12 hr or less, immediate, 12 to 30 hr, intermediate, and 30 hr or more, delayed). The natural history and pathophysiology of the 12 hr or less group matched that of capillary leak syndrome with a rapid fall in blood pressure, rise in hematocrit, massive edema, and congestion with leukocyte sequestration in both lung and liver, with only limited adrenal cortical hemorrhage. The 12 to 30 hr group matched the natural history of a consumptive hemorrhagic diatheses with a biophasic blood pressure response, limited change in hematocrit, a severe consumptive coagulopathy, severe adrenal cortical hemorrhage, and a moderate renal cortical tubular necrosis, but limited renal cortical thrombosis. The greater than 30 hr group matched the natural history of a microvascular thrombotic (hemolytic uremic) syndrome with a stable blood pressure, a fall in hematocrit associated with a massive renal cortical thrombosis with a severe medullary, and cortical tubular necrosis. We did not analyze these groups further (i.e., type of intervention etc.) once we found that time of survival correlated with a unique clinical syndrome, because based on these observations, we hypothesized that we could reproduce the immediate capillary leak and pulmonary failure, and the delayed microvascular thrombosis and renal failure syndromes experimentally. We reproduced the immediate (< 12 hr) and delayed (> 30 hr) responses by infusion of either tumor necrosis factor or C4b binding protein with sublethal E. coli. This provides models of the immediate and delayed as well as the intermediate responses to E. coli for study of mechanism and the efficacy of therapeutic interventions.

Stability of HBV DNA in cell lines and nude mouse-passaged tissues derived from human hepatocellular carcinoma

Human hepatitis B virus (HBV) infection has been closely linked to the occurrence of hepatocellular carcinoma (HCC). Hepatoma cell lines and nude mouse-passaged hepatoma tissues were used in this report to study the HBV DNA status in these cells after passage. DNA was extracted from seven hepatoma cell lines and three nude mouse passaged HCC lines. Southern blot hybridization technique was performed with either cloned HBV whole genome or subgenomic DNA fragments as probes to analyze the presence of HBV DNA. Integration of HBV DNA fragments was detected in one mouse passaged tissue, R. Hybridization with HBV subgenomic DNA revealed that there were some DNA rearrangements of the integrated HBV DNA in R. However, the integrated HBV DNA could not be detected in the cell line derived from R after in vitro cultivation for 2 years. Both episomal form and integrated HBV DNA were detected in a cell line NTU-h3. Episomal form HBV DNA ih NTU-h3 changed after several passages. HBV DNA in NTU-h3 was unstable after in vitro cultivation. Therefore, we concluded that the presence of HBV DNA might not be essential for the maintenance of the tumorigenicity of hepatoma and the nude mouse system was more stable for maintaining HBV DNA in HCC.

Radiofrequency catheter atrioventricular node ablation in patients with permanent cardiac pacing systems

Following successful RF ablation of the atrioventricular node (AVN), temporary pacing is necessary prior to insertion of a permanent pacemaker. The risks and inconvenience of temporary pacing could be avoided if a permanent pacemaker is already in place. This study reports the feasibility of RF ablation of the AVN in 27 patients (age 55 +/- 17 years, 15 males) with hypertrophic cardiomyopathy and pacemakers. Indications for AVN ablation were drug refractory atrial fibrillation in 24 patients, and rapid AVN conduction preventing septal pre-excitation by DDD pacemaker, inserted for relief of left ventricular outflow obstruction, in three cases. Sixteen patients had DDD devices and 11 patients had VVI devices. During RF ablation, each pacemaker was programmed to VVI at 50 beats/min. The ablation catheter was manipulated with fluoroscopic control to avoid close contact with or disturbance of the pacing leads. In 16 patients, RF ablation was performed immediately following pacemaker implantation but in the remaining patients, the AVN was ablated 6-32 months after pacemaker implantation. The power applied was 25-50 watts for a duration of 15-60 seconds. AV block was achieved in all cases but required 34 +/- 36 applications for 16.5 +/- 17.8 min/case. RF ablation consistently caused reversion to magnet rate in one patient and temporarily inhibited appropriate pacemaker discharge in another. However, no other pacemaker or lead malfunction was detected so that temporary pacing was not required in any case. At 6 +/- 3 months follow-up, all pacemakers were functioning normally without alteration in pacing parameters from baseline.(ABSTRACT TRUNCATED AT 250 WORDS)

Early bidirectional cavopulmonary shunt in young infants. Postoperative course and early results

BACKGROUND

Despite the recent wide applicability of the bidirectional cavopulmonary shunt, there is limited reported experience in performing these shunts in infants 6 months or younger.

METHODS AND RESULTS

Before October 1992, 17 consecutive infants aged 4.2 to 6.5 months (median, 6.1 months) underwent bidirectional cavopulmonary shunts. The diagnoses were hypoplastic left heart syndrome (n = 7), single right ventricle (n = 5), and single left ventricle (n = 5). All but 2 patients had prior palliative surgery. The bidirectional cavopulmonary shunt was performed early on an elective basis in 9 patients; the remaining patients had progressive cyanosis (6 patients), severe ventricular failure (1 patient), and coexisting restrictive bulboventricular foramen (1 patient). The median preoperative pulmonary arterial pressure and pulmonary vascular resistance were 15 mm Hg and 2.3 U.m2, respectively. One patient died; the overall hospital survival was 94%. The most common postoperative problem was transient systemic hypertension, observed in 14 (88%) of 16 survivors. Systemic arterial oxygen saturation increased from a median of 75% before surgery to a median of 85% after surgery (P < .05). The median hospital stay was 6 days. There were no late deaths during follow-up (median, 12.4 months). At postoperative cardiac catheterization performed in 9 of 16 survivors, there was no evidence of severe hypoxemia, shunt narrowing, or pulmonary arteriovenous fistulas. Of the 16 survivors, 6 have had a subsequent Fontan operation at a median age of 1.9 years; there were 5 survivors.

CONCLUSIONS

Early bidirectional cavopulmonary shunt in young infants has shown encouraging early results and provides improved oxygenation with low morbidity and mortality. We speculate that an early bidirectional cavopulmonary shunt on an elective basis may reduce the deleterious sequelae of chronic hypoxemia, long-term ventricular volume overload, and repeated palliative procedures, thus yielding a more suitable Fontan candidate.

Video-assisted thoracoscopic division of a vascular ring in an infant: a new operative technique

We report the first successful use of thoracoscopy and video-assisted thoracic surgery (TVATS) techniques to relieve extrinsic tracheoesophageal compression produced by a vascular ring. The patient was a 3-month-old infant with postprandial regurgitation and a diagnosis of double aortic arch. After an uncomplicated operation and recovery, the infant was discharged on the second postoperative day. Refinement of technique and instrumentation may allow wider application of video-assisted thoracoscopic techniques in pediatric patients.