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Biomedical subjects

C A Schmidt

Publications and source records attributed to C A Schmidt.

At least 91 records · Page 5Linked to original sources
PubMed1992

Rearrangements of T-cell receptor delta, gamma and beta genes in acute myeloid leukemia coexpressing T-lymphoid features.

In order to investigate the role of T-cell receptor (TcR)-delta and TcR-gamma gene rearrangements and/or deletions in acute myeloid leukemia (AML) coexpressing T-cell-associated antigens (i.e. CD2 and/or CD4 and/or CD7), we examined blasts from a selected group of 56 AML cases (25 children, 31 adults) coexpressing either of these antigens without cytoplasmic CD3 expression. Forty-four typical AML cases (7 children, 37 adults) without T-cell associated antigens were further studied as controls. Germline configuration of the TcR-delta gene was observed in 91 out of the total of 100 AML cases investigated. Eight of nine cases with rearranged or deleted TcR-delta genes coexpressed T-cell-associated antigens. Blast cells of 7/9 cases were classified as FAB M1, two as FAB M2. In six of these cases TcR-gamma gene rearrangements were also detected. TcR-delta alterations were predominantly found in children whose blasts coexpressed T-lymphoid associated antigens (6/25, 24%), but were rarely detected in adult AML with or without coexpression of T-cell antigens (2/31 and 0/37, respectively).

Acute Disease↗
PubMed1992

[Orthotopic liver transplantation in hepatic cirrhosis: on the problem of infection of the transplant with persistent hepatitis viruses].

269 orthotopic liver transplantations (OLT) were performed in 253 patients at our institution from September 1988 to May 1992. 121 patients had end-stage cirrhosis secondary to viral hepatitis type B, delta, or type non-A non-B and C respectively. Reinfection of the graft by persistent viruses is a potential complication in these cases. Passive immunization with anti-HBs hyperimmunoglobulin (HIg) can prevent clinically relevant reinfection of the graft in patients with hepatitis B virus (HBV) infection and low replication rates. Patients with high replication rates will rarely benefit from OLT. Patients with hepatitis delta virus (HDV) infection usually experience HDV reinfection of the graft with subsequent chronic hepatitis although prophylaxis with anti-HBs-HIg was performed. Treatment with interferon alpha had no apparent effect on the incidence of graft reinfection with HBV in this series, but the replication rate of HDV was reduced. Persistent hepatitis C viruses (HCV) usually infect the graft; this was demonstrated in 17 patients by means of the polymerase chain reaction. HCV infection usually causes a mild form of acute hepatitis with transition to a chronic course. Therefore the significance of persistent viral infection lies in the potential for chronic hepatitis in the transplanted organ rather than in the danger of acute injury of the allograft.

Biopsy, Needle↗
PubMed1992

Induction of differentiation in Friend-erythroleukemia cells by aclacinomycin A: early transient decrease in c-myc and c-myb mRNA levels.

Chemical inducers of the differentiation are known to cause an early transient decrease in c-myc and c-myb mRNA levels in Friend erythroleukemia cells preceding the down-regulation of c-myc and c-myb expression in the course of irreversible terminal differentiation. We therefore investigated the early effect of the potent differentiation-inducing anthracycline antitumor antibiotic, aclacinomycin A, on the c-myc and c-myb mRNA levels in the Friend cell line, F4-6, using Northern blot analysis. Aclacinomycin A induced a rapid decrease in the levels of c-myc and c-myb transcripts within 0.5-1 h and 2-3 h, respectively. The time course of decline in c-myc and c-myb expression was similar to that observed with dimethylsulfoxide or after transcription blockage brought about by a high concentration of actinomycin D. By 12 to 18 h after aclacinomycin A exposure, the c-myc and c-myb mRNA levels had returned to about pretreatment levels. When the cells were treated with adriamycin, an anthracycline that reduces cell proliferation in F4-6 cells without increasing differentiation, an early decrease in c-myc and c-myb expression was not observed. These results suggest that the transient decrease in c-myc and c-myb mRNA levels in F4-6 cells may be an early differentiation-related biochemical effect of aclacinomycin A.

Aclarubicin↗
PubMed1991

Decreased DNA topoisomerase II in daunorubicin-resistant Ehrlich ascites tumor cells.

We have previously shown that the multidrug-resistant EHR2/DNR+ cells, which overexpress P-glycoprotein, accumulate only about 20-30% of daunorubicin at steady state compared to the sensitive cells. These cells have been thought to be a "pure" P-glycoprotein cell line. We now report that the EHR2/DNR+ cells exhibit decreased DNA topoisomerase II catalytic activity. We also found that the amount of immunoreactive DNA topoisomerase II from these cells is about one-third that seen in the drug-sensitive cell line. In agreement with the decreased activity and amount of topoisomerase II, the number of DNA-protein complexes stabilized by teniposide (VM-26) was reduced by about 50% in nuclear extracts from EHR2/DNR+ cells. Furthermore, using an intact cell assay for DNA protein complexes, we found that the VM-26-stimulated complexes formed in the drug-resistant cells never reached the level seen in the drug-sensitive cells. Verapamil and Cremophor EL block P-glycoprotein-mediated efflux of "natural product" drugs and increase their accumulation in resistant cells. Coincubation of the EHR2/DNR+ cells with VM-26 and either of these modulators increased the number of complexes formed in the resistant cells. However, neither modulator increased the number of topoisomerase II-DNA complexes in the drug-resistant cells to the level seen in the EHR2 cells. We conclude that the resistance of EHR2/DNR+ cells is due in part to reduced amounts of DNA topoisomerase II. Furthermore, we note that a single cell line can express features of both P-glycoprotein-associated multidrug resistance and altered topoisomerase II-associated multidrug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Bullet fragment venous embolus to the heart: case report.

This report describes a case of bullet fragment embolus to the heart following a small-caliber gunshot wound to the mouth. Skull and C-spine films appeared to account for the projectile; however, chest X-ray followed by fluoroscopy and two-dimensional echocardiography demonstrated a venous missile embolus in the right heart. The bullet was palpated, trapped in the right ventricle, and easily extruded.

Adult↗
PubMed1991

Routine applications of DNA fingerprinting with the oligonucleotide probe (CAC)5/(GTG)5.

The use of DNA fingerprinting with synthetic oligonucleotides is illustrated for practical applications familiar in clinical diagnostics: pre- and postnatal zygosity determination and the monitoring of bone marrow transplantation. A simple method for non-radioactive detection is described which may be interesting for many diagnostic laboratories.

Bone Marrow Transplantation↗
PubMed1990

Platypnea-orthodeoxia as a cause of unexplained hypoxemia in an 82-yr-old female.

We describe an 82-yr-old patient with platypnea-orthodeoxia without identifiable lung disease in whom the diagnosis was suspected because of clinical history, echocardiography, and orthostatic measurement of arterial blood gases. Recumbent and upright cardiac catheterization techniques confirmed the presence of orthostatic variation in the degree of right to left shunt across the fossa ovalis. This was successfully treated by surgical closure of the interatrial communication in the region of the fossa ovalis.

Aged↗
PubMed1990

Differential expression of the oncoproteins c-myc and c-myb in human lymphoproliferative disorders.

Altered regulation of oncogene expression has been described in a variety of hematopoietic malignancies. In this study we analyzed the protein level of c-myc and c-myb in 15 established cell lines derived from lymphopoietic disorders and in 45 samples from patients with acute or chronic lymphatic leukemias. Oncoproteins were assayed by radioimmuno-precipitation with polyclonal rabbit antibodies. In B-cell derived lines, such as Burkitt lymphoma and plasmocytoma lines, we found high amounts of c-myc and no or low amounts of c-myb. In contrast, all T-cell-derived lines revealed high levels of c-myb. In addition, T-lymphoma cell lines of low malignancy also exhibited high levels of c-myc, while T-cell lines of high malignancy (acute T-lymphoblastic leukemias) exhibited moderate levels of c-myc. Of the 45 patient samples analyzed, only three (one B-prolymphocytic and two acute T-lymphoblastic leukemias) contained detectable amounts of myc or myb protein. Corresponding to the results found in established cell lines, the B-cell sample revealed a high level of c-myc but no c-myb, while the T-cell samples revealed high levels of c-myb and no or low levels of c-myc. We therefore conclude that the predominance of c-myc or c-myb expression in malignant lymphoproliferative disorders may be associated to the B-cell or T-cell lineage, respectively. Further, regarding the T-cell lines, there is a possible correlation between cell maturation and the level of c-myc found together with a consistently elevated c-myb.

Cell Line↗
PubMed1990

Soluble interleukin 2 receptors in patients after bone marrow transplantation.

An enzyme-linked immunosorbent assay was used to quantify soluble interleukin 2 receptor (IL2R) in the serum of 25 patients prior to allogeneic or autologous bone marrow transplantation and in the early post-transplantation period. A significant correlation between IL2R and the occurrence of fever and/or graft-versus-host disease (GVHD) could be shown. Patients with moderate to severe GVHD (grade II-IV) had significantly higher IL2R levels (median 480 U/ml) than patients without or with acute GVHD grade I (median 139 U/ml). In patients without or with acute GVHD grade I, significant differences in the maximum IL2R levels depended on the duration of fever greater than or equal to 38 degrees C. Evaluation of the peak IL2R levels in patients with fever lasting longer than 6 days led to a median of 260 U/ml and in patients with fever lasting less than 6 days to a median of 118 U/ml. In patients without or with acute GVHD grade I, who developed fever lasting longer than 6 days, IL2R levels started to rise with the onset of fever, reached peak values during temperature maximum and declined parallel with temperature normalization. In patients without or with acute GVHD grade I who developed fever lasting for only 6 days or less IL2R levels remained within the normal range. In patients with acute GVHD grade II-IV, IL2R levels began to rise with the onset of fever, and then continued to rise despite temperature normalization. The peak levels were reached in the early period of acute GVHD. Our observations in BMT patients show that severe infections and acute GVHD are associated with a stimulation of the immune system leading to elevated IL2R serum levels.

Bone Marrow Transplantation↗
PubMed1990

Surgery for thoracoabdominal aortic aneurysms.

From July 1985 to July 1989, Loma Linda University Medical Center evaluated 46 thoracoabdominal aortic aneurysms (TAAAs). Forty patients were taken to surgery--18 (45%) were operated on an emergency basis for reasons including rupture (12 patients, 30%), dissection (5 patients, 12.5%), and severe pain (1 patient). The overall mortality for all operated patients was five (12.5%-17% for emergency surgery versus 9% for elective surgery). Nonfatal complications occurred in 40 per cent of patients (16). The overall incidence of paraplegia was 10 per cent (4/40), emergency patients 17 per cent (3/18) versus elective patients 4.5 per cent (1/22). Careful preoperative evaluation, standardization of operative technique, and good postoperative management have improved the outlook for these patients who otherwise would progress to eventual rupture and death. Because mortality and morbidity are substantially reduced in elective patients, we recommend that all patients with TAAAs be evaluated for surgery as soon as diagnosis is made.

Adult↗
PubMed1989

Genetic characterization of the multidrug-resistant phenotype of VM-26-resistant human leukemic cells.

Our human T-cell leukemia line, CEM/VM-1, selected for resistance to VM-26 (teniposide), is cross-resistant to several drugs that interact with topoisomerase II, including VP-16 (etoposide), 4'-(9-acridinylamino)methanesulphon-m-anisidide, daunorubicin, and mitoxantrone. However, in contrast to cell lines exhibiting multidrug resistance (MDR) associated with overexpression of P-glycoprotein, this line is not cross-resistant to the Vinca alkaloids, is not impaired in drug accumulation, and does not overexpress the mdrl gene (Cancer Res., 47: 1297, 5455, 1987). More recently we found that nuclear extracts of these cells exhibit decreased topoisomerase II catalytic and cleavage activity, compared to the drug-sensitive line (Biochemistry, 1988). These results suggest that an alteration in topoisomerase II or a modulator of this enzyme may be responsible for this altered topoisomerase II-form of multidrug resistance (at-MDR). In the present work, we studied the somatic cell genetics of at-MDR. We produced hybrid cell lines by polyethylene glycol-mediated fusion of the CEM/VM-1 line with a hypoxanthine-guanine phosphoribosyl transferase-deficient, ouabain-resistant CEM line (CEM.AG1.OU1.5) that exhibits VM-26 sensitivity. Ten of the hybrid lines that grew in selective medium were randomly chosen for expansion and four were analyzed for both DNA content by flow cytometry and VM-26 sensitivity in a 72-h growth inhibition assay. The hybrid lines all contained approximately 2x DNA compared to unfused controls, indicating that the fusions were successful. The IC50 for VM-26 in 3 of the 4 lines was the same as that of the sensitive controls, ranging from 4.7 to 7.4 x 10(-8) M, and another was 76 x 10(-8) M. These data indicate that drug sensitivity was reconstituted by the hybridization procedure. By comparison, the VM-26 IC50 values in the CEM/VM-1 cells and CEM/VM-1 x CEM/VM-1 control "fusions" were 360 and 750 x 10(-8) M, respectively. To determine whether a topoisomerase II-mediated function was reconstituted in the hybrids, we measured drug-stimulated DNA cleavage ("cleavable complex formation"). Using 32P-labeled pBR322 DNA as substrate with nuclear extracts from drug sensitive cells, 100 microM VM-26 maximally stimulated DNA cleavage by approximately 11-fold compared to no-drug controls.(ABSTRACT TRUNCATED AT 400 WORDS)

Culture Media↗
PubMed1989

Immunocytochemical detection of p21ras expression in fresh human leukaemic cells and cell lines.

The expression of p21ras proteins was investigated by immunocytochemistry in permanent cell lines and in fresh human leukaemic cells. While high and low levels of p21ras could be detected in most of the cell lines, no significant p21ras immunoreactivity was noted in cells of ten human acute and chronic leukaemias. Thus, notwithstanding its possible role in the initial transformation process in human leukaemias, p21ras expression appears not to be an irrevocable requirement for the maintenance of the transformed state.

Antibodies, Monoclonal↗
PubMed1989

Increased ATP requirement for activity of and complex formation by DNA topoisomerase II from human leukemic CCRF-CEM cells selected for resistance to teniposide.

We showed previously that nuclear extracts from teniposide (VM-26)-resistant sublines of the human leukemic cell line, CCRF-CEM, exhibited decreased DNA topoisomerase II activity and ability to form drug-stabilized covalent protein-DNA complexes (Danks et al., Biochemistry 27:8861-8869; 1988). In the present study, we found that nuclear extracts of these sublines (approximately 50- and approximately 140-fold resistant to VM-26) required 2 and 8 times more adenosine 5'-triphosphate (ATP), respectively, to achieve half-maximal stimulation of unknotting activity compared to extracts from the sensitive cells. When novobiocin, a competitive inhibitor of ATP binding to topoisomerase II, was included in the reaction, this ATP requirement increased 2.5- to 4-fold with the CEM cell extracts and 3.5- to 12-fold with the resistant cell extracts. ATP produced a dose-dependent increase in VM-26-stabilized topoisomerase II-DNA covalent complexes with nuclear extracts from all three cell lines. Extracts from resistant cells, however, formed 40-80% fewer complexes than those from sensitive cells. A similar decrease was seen with 4'-[(9-acridinyl)amino]methanesulphon-m-anisidide, to which the cells are cross-resistant. With nuclear extracts from sensitive cells, the tetralithium salt of 5'-adenylylimidodiphosphate (AMP-PNP), a nonhydrolyzable analog of ATP, was as effective as ATP in promoting the formation of drug-stabilized enzyme-DNA complexes. With extracts from the resistant cell nuclei, however, AMP-PNP was about half as effective as ATP in promoting complex formation. Our results demonstrate that the effect of ATP on strand passing activity of and drug-stabilized complex formation by topoisomerase II is decreased in the nuclear extracts from the drug-resistant cells and suggest a possible basis for this form of drug resistance.

Adenosine Triphosphate↗
PubMed1988

Altered catalytic activity of and DNA cleavage by DNA topoisomerase II from human leukemic cells selected for resistance to VM-26.

The simultaneous development of resistance to the cytotoxic effects of several classes of natural product anticancer drugs, after exposure to only one of these agents, is referred to as multiple drug resistance (MDR). At least two distinct mechanisms for MDR have been postulated: that associated with P-glycoprotein and that thought to be due to an alteration in DNA topoisomerase II activity (at-MDR). We describe studies with two sublines of human leukemic CCRF-CEM cells approximately 50-fold resistant (CEM/VM-1) and approximately 140-fold resistant (CEM/VM-1-5) to VM-26, a drug known to interfere with DNA topoisomerase II activity. Each of these lines is cross-resistant to other drugs known to affect topoisomerase II but not cross-resistant to vinblastine, an inhibitor of mitotic spindle formation. We found little difference in the amount of immunoreactive DNA topoisomerase II in 1.0 M NaCl nuclear extracts of the two resistant and parental cell lines. However, topoisomerase II in nuclear extracts of the resistant sublines is altered in both catalytic activity (unknotting) of and DNA cleavage by this enzyme. Also, the rate at which catenation occurs is 20-30-fold slower with the CEM/VM-1-5 preparations. The effect of VM-26 on both strand passing and DNA cleavage is inversely related to the degree of primary resistance of each cell line. Our data support the hypothesis that at-MDR is due to an alteration in topoisomerase II or in a factor modulating its activity.

Cell Cycle↗
PubMed1987

Impalement injuries to the thorax as a result of motor vehicle accidents.

We report three cases of thoracic impalement by large-diameter steel pipes as a result of motor vehicle accidents. The steel pipes were removed in all patients in the operating room under general anesthesia and controlled circumstances. Despite the dramatic nature and presentation of these injuries, all 3 patients had nonlethal injuries and have recuperated without sequelae. Orderly care with standard surgical procedures is required and will give good results.

Accidents, Traffic↗