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Biomedical subjects

D Frank

Publications and source records attributed to D Frank.

At least 55 records · Page 3Linked to original sources
PubMed1998

Atrial fibrillation after bypass surgery: does the arrhythmia or the characteristics of the patients prolong hospital stay?

STUDY OBJECTIVES: The goal of this study was to determine whether prolonged hospital stay associated with atrial fibrillation or flutter (AF) after coronary artery bypass graft (CABG) surgery is attributable to the characteristics of patients who develop this arrhythmia or to the rhythm disturbance itself. DESIGN: An investigation was conducted through a prospective case series. SETTING: Patients were from a single urban teaching hospital. PARTICIPANTS: Consecutive patients undergoing isolated CABG surgery between December 1994 and May 1996 were included in the study. INTERVENTIONS: No interventions were involved. RESULTS: Of 436 patients undergoing isolated CABG surgery, 101 (23%) developed AF. AF patients were older and more likely to have obstructive lung disease than patients without AF, but both patients with and without AF had similar left ventricular function and extent of coronary disease. ICU and hospital stays were longer in patients with AF. Multivariate analysis, adjusted for age, gender, and race, demonstrated that postoperative hospital stay was 9.2+/-5.3 days in patients with AF and 6.4+/-5.3 days in patients without AF (p<0.001). CONCLUSIONS: Although AF is strongly associated with advanced age, most of the prolonged hospital stay appears to be attributable to the rhythm itself and not to patient characteristics.

Aged↗
PubMed1998

Hemostasis activation markers in acute renal failure.

Fibrinopeptide A and thrombin-antithrombin III complex were used respectively as markers for in vivo thrombin formation and beta-thromboglobulin as a marker for platelet activation. In cases of acute renal failure (ARF) a heightened plasma concentration in the hemostasis activation markers may occur, because of a renal elimination disturbance, without a previous activation of the hemostasis. In order to check the validity of fibrinopeptide A, thrombin-antithrombin III complex and beta-thromboglobulin as markers for the hemostasis activation in cases of ARF we examined 32 patients prior to renal replacement therapy. A significant rise in fibrinopeptide A (x +/- SD: 34 +/- 22 ng/mL, ref < 3.0), thrombin-antithrombin III complex (19 +/- 15 ng/mL, ref 1.0-4.0) and beta-thromboglobulin (149 +/- 58 U/mL, ref 10-40) was found. None of the parameters examined showed a correlation to the serum creatinine. A correlation was observed respectively between fibrinopeptide A (r = 0.34, p < .05), beta-thromboglobulin (r = 0.39, p < .05) and the beta-thromboglobulin/creatinine coefficient (0.50 +/- 0.30, r = 0.72, p < .001) on the one side and the thrombin-antithrombin III complex on the other. A greater rise in the concentration of all parameters in patients with disseminated intravascular coagulation (DIC) was established, in contrast to patients without DIC (fibrinopeptide A: 44 +/- 31 vs. 32 +/- 20 ng/mL, beta-thromboglobulin: 169 +/- 57 vs. 144 +/- 60 U/mL, thrombin-antithrombin III complex 40 +/- 21 vs. 14 +/- 7 ng/mL, p < .05). Fibrinopeptide A and beta-thromboglobulin/creatinine coefficient in combination with the thrombin-antithrombin III complex can be employed as markers for the activation of hemostasis in cases of ARF there is no direct relationship between restricted kidney function in ARF and the plasma concentration of these markers, which behave similarly in spite of their varying elimination patterns.

Acute Kidney Injury↗
PubMed1997

Human mitogen-activated protein kinase kinase 4 as a candidate tumor suppressor.

Mitogen-activated protein kinases function in signal transduction pathways that are involved in controlling key cellular processes in many organisms. A mammalian member of this kinase family, MKK4/JNKK1/SEK1, has been reported to link upstream MEKK1 to downstream stress-activated protein kinase/JNK1 and p38 mitogen-activated protein kinase. This mitogen-activated protein kinase pathway has been implicated in the signal transduction of cytokine- and stress-induced apoptosis in a variety of cell types. Here, we report that two human tumor cell lines, derived from pancreatic carcinoma and lung carcinoma, harbor homozygous deletions that eliminate coding portions of the MKK4 locus at 17p, located approximately 10 cM centromeric of p53. In addition, in a set of 88 human cancer cell lines prescreened for loss of heterozygosity, we detected two nonsense and three missense sequence variants of MKK4 in cancer cell lines derived from human pancreatic, breast, colon, and testis cells. In vitro biochemical assays revealed that, when stimulated by MEKK1, four of the five altered MKK4 proteins lacked the ability to phosphorylate stress-activated protein kinase. Thus, the incidence of coding mutations of MKK4 in the set of cell lines is 6 of 213 (approximately 3%). These findings suggest that MKK4 may function as a suppressor of tumorigenesis or metastasis in certain types of cells.

DNA, Neoplasm↗
PubMed1997

Oncogenic H-ras stimulates tumor angiogenesis by two distinct pathways.

The switch from a quiescent tumor to an invasive tumor is accompanied by the acquisition of angiogenic properties. This phenotypic change likely requires a change in the balance of angiogenic stimulators and angiogenic inhibitors. The nature of the angiogenic switch is not known. Here, we show that introduction of activated H-ras into immortalized endothelial cells is capable of activating the angiogenic switch. Angiogenic switching is accompanied by up-regulation of vascular endothelial growth factor and matrix metalloproteinase (MMP) bioactivity and downregulation of tissue inhibitor of MMP. Furthermore, we show that inhibition of phosphatidylinositol-3-kinase leads to partial inhibition of tumor angiogenesis, thus demonstrating that activated H-ras activates tumor angiogenesis through two distinct pathways. Finally, we show evidence for two forms of tumor dormancy.

Androstadienes↗
PubMed1997

The IPL gene on chromosome 11p15.5 is imprinted in humans and mice and is similar to TDAG51, implicated in Fas expression and apoptosis.

We searched for novel imprinted genes in a region of human chromosome 11p15.5, which contains several known imprinted genes. Here we describe the cloning and characterization of the IPL ( I mprinted in P lacenta and L iver) gene, which shows tissue-specific expression and functional imprinting, with the maternal allele active and the paternal allele relatively inactive, in many human and mouse tissues. Human IPL is highly expressed in placenta and shows low but detectable expression in fetal and adult liver and lung. Mouse Ipl maps to the region of chromosome 7 which is syntenic with human 11p15.5 and this gene is expressed in placenta and at higher levels in extraembryonic membranes (yolk sac), fetal liver and adult kidney. Mouse and human IPL show sequence similarity to TDAG51 , a gene which was shown to be essential for Fas expression and susceptibility to apoptosis in a T lymphocyte cell line. Like several other imprinted genes, mouse and human IPL genes are small and contain small introns. These data expand the repertoire of known imprinted genes and will be helpful in testing the mechanism of genomic imprinting and the role of imprinted genes in growth regulation.

Amino Acid Sequence↗
PubMed1997

Alterations in dopamine clearance and catechol-O-methyltransferase activity by dopamine infusions in children.

OBJECTIVE: To determine the role of catechol-O-methyltransferase (COMT) in the biodisposition of pharmacologic concentrations of dopamine. DESIGN: The study was an open-label dose escalation trial in which dopamine was employed as the sole exogenous catecholamine. The dosage was adjusted to achieve improvements in cardiac output or to augment renal function. SETTING: A 16-bed pediatric intensive care unit serving both medical and surgical patients. PATIENTS: The study was performed using 14 dopamine-treated and five untreated control patients. Children ranged in age from 16 days to 12 yrs; five of the treated patients and two of the untreated controls were female. All but one of the study patients were enrolled within 24 hrs of palliative or corrective surgery for congenital heart disease. Control patients had noncardiac surgical procedures. Both treated and control groups were similar with respect to severity of illness, as judged by Therapeutic Intervention Scoring System score. INTERVENTIONS: All treated patients received dopamine as a continuous intravenous infusion. Infusion rates were determined by caregivers and ranged from 3.0 to 20 micrograms/kg/min. MEASUREMENTS AND MAIN RESULTS: Serial, timed blood samples were obtained from patients and control subjects for the determination of plasma dopamine concentrations and for the determination of mononuclear cell COMT activity. Measured rates of dopamine infusion (3.0 to 18.3 micrograms/kg/min) were consistently less than the nominal rates (3.0 to 20.0 micrograms/kg/min) of infusion (p < .0001) due in part to calculations based on the hydrochloride salt rather than dopamine base. At similar steady-state infusion rates, plasma dopamine concentrations varied over a four-fold range, with steady-state concentrations at even the lowest infusion rate exceeding endogenous concentrations by at least ten-fold. Variations in steady-state plasma dopamine concentration reflected large age-associated variations in dopamine clearance, which was found to be saturable at concentrations of > 200 ng/mL. Mononuclear cell COMT activity was assessed simultaneously in these patients. Baseline COMT activity varied over a six-fold range and was unrelated to dopamine clearance or patient age. COMT activity increased two- to six-fold in dopamine-treated patients with plasma steady-state dopamine concentrations of > 100 ng/mL. CONCLUSIONS: These data demonstrate marked age and concentration-dependent differences in dopamine clearance that account for large interindividual differences in the steady-state plasma dopamine concentrations in patients receiving similar infusion rates. While concomitant variability in COMT activity is observed, the lack of correlation between dopamine clearance and COMT activity suggests that COMT is not rate-limiting for the clearance of exogenously administered dopamine.

Catechol O-Methyltransferase↗
PubMed1996

Feasibility and safety of 1-day postoperative hospitalization for carotid endarterectomy.

OBJECTIVE: To determine whether 1-day postoperative hospitalization after carotid endarterectomy is safe and the degree to which this can be achieved. DESIGN: Consecutive sample series of all carotid endarterectomies performed by a single surgical group. SETTING: A single tertiary-care hospital. PATIENTS: All who underwent carotid endarterectomy. Patients with procedures combined with coronary revascularization and patients undergoing the first part of a staged bilateral carotid endarterectomy performed in 1 hospitalization were excluded. INTERVENTION: In December 1993, a fast-track protocol was initiated, aiming for a 1-day stay after carotid endarterectomy without admission to an intensive care unit (ICU). Before this date, postoperative care included obligatory monitoring for at least 1 night in an ICU. MAIN OUTCOME MEASURES: Length of stay, admission to and stay in the ICU, complications, and hospital readmission rate. RESULTS: Over a 21-month period, 152 patients had 163 carotid endarterectomies. Of these, 124 were elective and 39 urgent (patients with a critical stenosis). Indications were stroke (n = 14 [8.6%]), transient ischemic attack (n = 50 [30.7%]), amaurosis fugax (n = 36 [22.1%]), and asymptomatic stenosis (n = 63 [38.7%]). General anesthesia was used for 159 procedures, cervical block for 4. Mean operation time was 2.6 hours. Postoperative stay was 1 day for 82 procedures (50%), 2 days for 49 procedures (30%), 3 days for 12 procedures (7%), and longer for 20 procedures (12%). In the last half of the study, 61% of patients (50/82) were discharged on postoperative day 1 and 87% (71/82) by postoperative day 2. One hundred three patients went to a surgical floor postoperatively. Overall, 60 patients went to the ICU, but only 18 (22%) of the last 82 procedures required ICU admission. The total stay averaged 3.8 days. Twenty-one patients (13%) experienced complications, including 3 deaths within 30 days and 5 neurological deficits. There were 14 early readmissions, but none was attributable to discharge on the first or second postoperative day. CONCLUSIONS: Early discharge home after carotid endarterectomy is safe and efficacious, and obligatory admission to an ICU is not necessary. At least 60% of patients who undergo carotid endarterectomy can have a postoperative stay of 1 day, and more than 80% can be discharged by postoperative day 2. A short postoperative stay is not associated with a significant risk of readmission for complications.

Adult↗
PubMed1996

Hemostatic alterations during continuous venovenous hemofiltration in acute renal failure.

In order to determine changes in hemostasis occurring during continuous venovenous hemofiltration (CVVH), we made a prospective study of 14 patients with acute renal failure. Fibrinopeptide A, thrombin-antithrombin III complex, beta-thromboglobulin and platelet retention were determined serially. Fibrinopeptide A (x +/- SD: 33 +/- 20 ng/ml, ref. < 3.0) and thrombin-antithrombin III complex (11 +/- 5 ng/ml, ref. 1.0-4.0) were enhanced prior to commencement of treatment but showed no further increase during therapy. Platelet retention (Hellem II, ref. 60-99%) fell from 39 +/- 32% before treatment to 16 +/- 15% after treatment, while the beta-thromboglobulin/creatinine ratio (ref. 0.23-0.41) rose from 0.39 +/- 0.20 to 0.64 +/- 0.44. Via platelet activation, CVVH leads to a reinforcement of the existing platelet dysfunction (thrombocytopathy), without influencing plasmatic coagulation. In order to analyze the influence of pre-existing hemostatic alterations on filter running time during CVVH, 60 patients were examined retrospectively in a second study. Filter running time, global coagulation tests, fibrinogen, antithrombin III, platelet count and hematocrit were registered daily. There was no significant correlation between filter running time and fibrinogen concentration, thrombin time, platelet count or hematocrit. Apart from filter occlusion, no thrombotic complications were observed. The frequency of filter occlusion increased with falling activated clotting time (ACT) (p < 0.05). Rising platelet count led to an increase in heparin dose (p < 0.05), primarily due to the anti-heparin effect of platelet factor 4.

Acute Kidney Injury↗
PubMed1995

Competition between noggin and bone morphogenetic protein 4 activities may regulate dorsalization during Xenopus development.

Bone morphogenetic protein 4 (BMP-4) induces ventral mesoderm but represses dorsal mesoderm formation in Xenopus embryos. We show that BMP-4 inhibits two signaling pathways regulating dorsal mesoderm formation, the induction of dorsal mesoderm (Spemann organizer) and the dorsalization of ventral mesoderm. Ectopic expression of BMP-4 RNA reduces goosecoid and forkhead-1 transcription in whole embryos and in activin-treated animal cap explants. Embryos and animal caps overexpressing BMP-4 transcribe high levels of genes expressed in ventral mesoderm (Xbra, Xwnt-8, Xpo, Mix.1, XMyoD). The Spemann organizer is ventralized in these embryos; abnormally high levels of Xwnt-8 mRNA and low levels of goosecoid mRNA are detected in the organizer. In addition, the organizer loses the ability to dorsalize neighboring ventral marginal zone to muscle. Overexpression of BMP-4 in ventral mesoderm inhibits its response to dorsalization signals. Ventral marginal zone explants ectopically expressing BMP-4 form less muscle when treated with soluble noggin protein or when juxtaposed to a normal Spemann organizer in comparison to control explants. Endogenous BMP-4 transcripts are downregulated in ventral marginal zone explants dorsalized by noggin, in contrast to untreated explants. Thus, while BMP-4 inhibits noggin protein activity, noggin downregulates BMP-4 expression by dorsalizing ventral marginal zone to muscle. Noggin and BMP-4 activities may control the lateral extent of dorsalization within the marginal zone. Competition between these two molecules may determine the final degree of muscle formation in the marginal zone, thus defining the border between dorsolateral and ventral mesoderm.

Animals↗
PubMed1995

Oncostatin M induces association of Grb2 with Janus kinase JAK2 in multiple myeloma cells.

Oncostatin M (OSM) is a 28-kD glycoprotein recently identified as a growth factor for human multiple myeloma cells. It belongs to a family of distantly related cytokines that includes interleukin 6, ciliary neurotrophic factor, leukemia-inhibitory factor, and interleukin 11. These cytokines initiate signaling by inducing either homodimerization of gp130 or heterodimerization of gp130 with leukemia-inhibitory factor receptor beta components. Such dimerization in turn activates receptor-associated tyrosine kinases. In the present study using U266B1 human multiple myeloma cells, we show that OSM induces tyrosine phosphorylation and activation of JAK2, but not JAK1 or Tyk2, kinases. The results also demonstrate that OSM induces direct interaction of JAK2 kinase with Grb2, an SH2/SH3 domain containing adaptor protein. The SH2 domain of Grb2 is directly associated with tyrosine-phosphorylated JAK2. Furthermore, the presence of Sos in the JAK2-Grb2 complex suggests a role for Ras in OSM-transduced signaling.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Posttransplantation lymphoproliferative disorders frequently contain type A and not type B Epstein-Barr virus.

Two families of Epstein-Barr virus (EBV), type A and type B, have been defined on the basis of sequence divergence in the EBNA-2 gene. Type A EBV immortalizes B cells more efficiently in vitro and infects immunocompetent individuals more commonly than type B EBV. However, increased rates of infection by type B EBV are seen in immunocompromised hosts and in many lymphoid neoplasms associated with immunocompromise. The posttransplantation lymphoproliferative disorders (PT-LPDs) are a heterogeneous group of B-cell neoplasms that arise in the setting of immunosuppressive therapy, and are associated with EBV infection. Whether type A and/or type B EBV are associated with PT-LPDs is unknown. Therefore, we investigated 27 PT-LPD lesions from 22 solid-organ transplant recipients by polymerase chain reaction (PCR) at the EBNA-2 and EBNA-3c loci to detect sequence deletions that distinguish the two EBV families. Another locus, EBER, was examined by single-strand conformation polymorphism analysis (SSCP), in conjunction with direct sequencing in selected cases. Type A EBV was found in 24 of 27 cases (89%) as seen by amplification of the EBNA-2 and EBNA-3c regions. Four different EBER polymorphisms were detected, confirming the presence of different type A EBV isolates among these cases. Three cases were negative for infection by EBV. Surprisingly, despite the immunocompromised state of the hosts, none of the 27 PT-LPD lesions harbored type B EBV. Thus, although type B EBV may commonly infect peripheral blood lymphocytes in immunocompromised individuals, they do not appear to induce readily PT-LPD formation.

Antigens, Viral↗
PubMed1995

The PKD1 gene produces a developmentally regulated protein in mesenchyme and vasculature.

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common human genetic diseases. In addition to polycystic kidneys, the disease can cause cystic changes in liver and other organs, cardiac valvular insufficiency and cerebral arterial aneurysms. Using antibodies raised against the predicted gene product of PKD1, which is mutated in about 85% of ADPKD cases, we show that PKD1 is a 530-kD protein localized to the extracellular matrix of kidney, liver and cerebral blood vessels. We discovered that the PKD1 protein was highly expressed in the mesenchyme of developing kidney and liver, transiently localized in the developing glomerulus and juxtaglomerular apparatus and restricted to perivascular, extraglomerular areas in adult renal cortex. These data suggest that the PKD1 protein plays a role in renal and hepatic morphogenesis.

Adult↗
PubMed1995

Evidence for a lymphotropic nature of circulating plasmacytoid monocytes: findings from a case of CD56+ chronic myelomonocytic leukemia.

Because the cells previously designated plasmacytoid T cells share major immunophenotypic features with cells of the mononuclear-phagocyte system, they have been re-named and are now known as plasmacytoid monocytes (PM). We describe a unique case of chronic myelomonocytic leukemia with circulating PM. The patient, a 48-year-old man, presented initially with refractory anemia. Four years later his general condition deteriorated, accompanied by an increase in leukocytes to 200,000/microliters blood. The bone marrow histology was interpreted as compatible with a diagnosis of chronic myelomonocytic leukemia. Two months before he died, the patient developed generalized lymphadenopathy clinically simulating malignant lymphoma. Histologic examination of an axillary lymph node revealed diffuse infiltration by PM. The PM in the lymph node and some circulating cells closely resembling PM expressed L-selectin, a finding that could be interpreted as a morphologic correlate of their marked lymphotropism. The detection of large numbers of CD56/CD33 double-positive circulating blast cells by FACS analysis strongly supported the diagnosis of a leukemia of myelogenous origin. The patient died of tumor cachexia. Autopsy revealed widespread leukemic infiltrates (always containing clusters of PM) in bone marrow, spleen, liver, lymph nodes, and mucosa-associated lymphoid tissue of the oropharynx. The final diagnosis was one of chronic myelomonocytic leukemia with marked lymphotropism and partial differentiation towards PM. We consider that the rare instances of a hematologic tumor with differentiation towards PM should be classified amongst the myelogenous leukemias.

Antigens, CD↗
PubMed1995

Characterization of Pseudomonas aeruginosa-induced MDCK cell injury: glycosylation-defective host cells are resistant to bacterial killing.

As a model for bacterium-induced epithelial cell injury, we have studied the interaction of Pseudomonas aeruginosa with polarized Madin-Darby canine kidney (MDCK) cells grown on filters. Following an initial period of bacterial adhesion, foci of injured host cells, which consisted of a central region of cell debris, surrounded by cells that were permeable and apparently necrotic, were formed. Host cell death was quantified by measuring the increased permeability of the monolayer to the macromolecular tracer [14C]inulin. Using this MDCK model system, we have identified bacterial and host cell factors necessary for the host cell damage. The ability of P. aeruginosa to cause MDCK cell damage was independent of elastase or exotoxin A production. In contrast, bacteria with a mutation in the regulatory locus exsA (which are deficient in exoenzyme S production) neither bound to nor caused host cell injury. MDCK cells with defects in cell surface glycosylation were resistant to cell injury, indicating that bacteria may require host cell glycolipids and/or glycoproteins as points of adhesion to cause subsequent host cell injury.

Animals↗
PubMed1994

Sp1 elements protect a CpG island from de novo methylation.

Animal somatic cell DNA is characterized by a bimodal pattern of methylation: tissue-specific genes are methylated in most cell types whereas housekeeping genes have 5' CpG islands which are constitutively unmethylated. Because methyl moieties derived from the gametes are erased in the morula and early blastula, this profile must be re-established in every generation; this is apparently accomplished by a wave of non-CpG island de novo methylation that occurs at implantation. Using transfection into embryonic stem cells and transgenic mice as a model system, we now show that Sp1 elements play a key role in protecting a CpG island in the adenine phosphoribosyltransferase (APRT) gene from de novo methylation. This recognition mechanism represents a critical step in embryogenesis, as it is responsible for setting up the correct genome methylation pattern which, in turn, is involved in regulating basal gene expression in the organism.

Adenine Phosphoribosyltransferase↗
PubMed1994

Nipple pain.

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Breast Feeding↗