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Biomedical subjects

J E Larson

Publications and source records attributed to J E Larson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Use of CA 125 to monitor patients with ovarian epithelial carcinomas.

The CA 125 radioimmunoassay has been increasingly used to monitor the course of patients with ovarian epithelial carcinomas. The purpose of this report is to describe our experience in the use of this assay and to better define its clinical utility. Fifty-one patients had serum CA 125 follow-up during primary chemotherapy. All 51 patients demonstrated either a normal CA 125 level at the completion of chemotherapy or a substantial fall in CA 125 values with treatment. In 48 of 51 patients, the drop in CA 125 levels was temporally related to the clinical regression or remission of tumor. Forty of these patients underwent second-look laparotomy; 23 patients (58%) had residual disease. A total of 45 patients had serum CA 125 determinations at the time of second-look laparotomy. Eight patients with microscopic disease and 11 of 18 patients with gross residual disease had a "negative" (less than 35 U/ml) CA 125 level. The predictive value of an elevated CA 125 level was 1.00. However, the predictive value of a negative value was only 0.50. Hence, a negative CA 125 level cannot be a substitute for a second-look laparotomy. Only 7 of 18 patients (39%) with gross residual disease at second-look surgery had an elevated CA 125 level. Patients with an elevated CA 125 and gross residual tumor at the second-look laparotomy uniformly demonstrated large, bulky disease. Furthermore, the survival of patients with gross residual disease at second-look laparotomy correlated with the preoperative CA 125 value. Serum CA 125 determinations also show promise in the follow-up of patients with a negative second-look laparotomy. The serum CA 125 level from patients with a "negative" second-look laparotomy can become elevated months before recurrent disease is appreciated.

Actuarial Analysis↗
PubMed1989

Pelvic fibromatosis: case report and review of literature.

The case report of a patient with pelvic fibromatosis is described. Excision of the tumor without sacrificing organs or major vessels was performed. Although not malignant, this tumor can be life-threatening due to its locally invasive properties. A variety of therapeutic options are discussed.

Adult↗
PubMed1989

Management of malignant, mixed mesodermal tumors of the uterus.

Forty-two patients with malignant, mixed mesodermal tumors of the uterus were identified by retrospective chart review. Only 2 patients were premenopausal at the time of diagnosis. Six of the patients had previously received pelvic radiotherapy. Surgical/pathologic findings were inconsistent with clinical staging in 17 of the patients. Patients with stage I tumors were found to have extrauterine extension of tumor in 39% of the cases. Overall, 2- and 5-year actuarial survival rates were 40 and 18%, respectively. The surgical extent of disease was a major prognostic factor in patient survival (P = 0.006). Patients with tumors showing no invasion or invasion limited to the inner two-thirds of the myometrium also demonstrated a significant survival advantage as compared to those with deeper myometrial invasion (P = 0.02). However, no statistically significant relationship was demonstrated between survival and patient age, the nature of the sarcomatous element (homologous or heterologous), or the presence of cervical involvement. Patients with recurrent or persistent disease did poorly; only 4 patients have survived more than 1 year after documentation of recurrent disease. Two patients had prolonged disease stabilization with radiotherapy and cisplatin. Another patient with pulmonary metastases had a 6-month, complete response to cisplatin.

Adult↗
PubMed1988

In vivo existence of left-handed DNA.

A genetic-biochemical assay has been developed to investigate the in vivo existence and consequences of unusual DNA structures. Left-handed DNA was shown to exist in living Escherichia coli. The EcoRI methyltransferase gene (temperature-sensitive) was cloned to serve as a probe for perturbed GAATTC sites in vivo. This plasmid was cotransformed with different plasmids containing inserts that had varying capacities to form left-handed helices or cruciforms with a target EcoRI site in the center or at the ends of the inserts. Inhibition of methylation in vivo was found for the stable inserts with the longest left-handed helices. In vitro methylation with the purified M.EcoRI enzyme agreed with the in vivo results.

Bacterial Proteins↗
PubMed1988

Cytosine methylation as an effector of right-handed to left-handed DNA structural transitions.

Cytosine methylation has energetic and structural influences on left-handed Z-DNA formation in supercoiled plasmids. The restriction and modification enzymes from Haemophilus haemolyticus (HhaI and M.HhaI) provide a system to locate and analyze small segments of Z-DNA in large supercoiled plasmids. An approach is outlined that uses M.HhaI as an in vivo conformational probe for the detection of unusual DNA structures in a living cell. Also, characteristic features of the M.HhaI gene and protein are discussed.

5-Methylcytosine↗
PubMed1988

Multiple DNA secondary structures in perfect inverted repeat inserts in plasmids. Right-handed B-DNA, cruciforms, and left-handed Z-DNA.

The capabilities of five recombinant plasmids, containing relatively long (approximately 60-100 base pairs) perfect inverted repeat (IR) inserts, to support supercoil stabilized non-B-DNA structures were studied in vitro. The IRs were also alternating purine-pyrimidine sequences, thus, each could form either left-handed Z-DNA or cruciforms. Single-strand specific endonucleases, restriction endonucleases and methylases, and OsO4 modifications were used to characterize the DNA structures. Two-dimensional gel electrophoretic studies indicated that three of the five IRs formed both cruciforms and Z-DNA. (C-G) containing inserts preferred to form Z-DNA, whereas (T-G) sequences favored cruciforms. In vivo supercoil relaxation experiments demonstrated the existence of cruciforms in Escherichia coli. The physiological significance of these structures is discussed.

Base Sequence↗
PubMed1988

Methylation of cytosine in the 5-position alters the structural and energetic properties of the supercoil-induced Z-helix and of B-Z junctions.

The structural and energetic consequences of cytosine methylation in the 5-position on the supercoil-dependent B-Z equilibrium in alternating dC-dG sequences cloned into recombinant plasmids were investigated. The helical parameters determined with the band shift method for right-handed [10.7 base pairs (bp)/turn] and left-handed (12.8 bp/turn) 5MedC-dG inserts were different from the helical repeat values for unmethylated dC-dG inserts (10.5 bp/turn in the right-handed and 11.5 bp/turn in the left-handed form). We analyzed the thermodynamic parameters delta GBZ (free energy difference per base pair between right-handed and left-handed helix structure), delta Gjx (free energy for formation of one B-Z junction), and b (helix unwinding at a junction region) for varying lengths of dC-dG inserts by two-dimensional gel electrophoresis and application of a statistical mechanics model. A comparison of plasmids fully methylated in vitro with HhaI methylase and their unmethylated counterparts revealed that delta Gjx is not significantly changed by cytosine methylation. However, this base modification results in an approximate 3-fold decrease of delta GBZ and an approximate 2-fold decrease of the unwinding b at B-Z junction regions. Analysis of a pair of related plasmids, each containing two dC-dG blocks, revealed qualitatively different transition behaviors. When the two dC-dG blocks were separated by 95 bp of a mixed sequence, they underwent independent B to Z transitions with separate nucleation events and junction formations. When the two blocks were separated by only a 4 bp GATC sequence, only one nucleation event was necessary, and the Z-helix spread across the nonalternating GATC region.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA Topoisomerases, Type I↗
PubMed1988

The B- to Z-DNA equilibrium in vivo is perturbed by biological processes.

Right-handed B and left-handed Z conformations coexist in equilibrium in portions of plasmids in Escherichia coli. The equilibria are influenced by the length of the sequences that undergo the structural transitions and are perturbed by biological processes. The composite results of three types of determinations indicate a supercoil density of -0.025 in vivo. The coexistence of alternative DNA conformations in living cells implies the potential of these structures or their transitions for important functions in genetic regulatory processes.

DNA↗
PubMed1988

The effect of experimental maternal hypoxia on fetal lung growth.

Timed-pregnant rats at a gestational age of 14 days were exposed to 10% ambient oxygen (normobaric hypoxia) and compared to pair-fed animals of the same gestation and controls fed ad libitum. The lungs of the offspring were analyzed morphometrically and biochemically at day 21 of gestation after cesarean section. The hypoxic mothers and the pair-fed mothers showed similar diminution of weight gain and their fetuses showed growth retardation, more so in those of the hypoxic mothers. The lung volumes and weights were significantly different in the offspring of hypoxic and pair-fed mothers compared to those of mothers fed ad libitum. However, the lung volume and lung weight to body weight ratios were not different between groups, including pair-fed and hypoxic, and lung size was proportional to the amount of general growth segment in all. Morphometric analysis showed the volume proportion of saccular air, saccular wall, conducting airways, and nonparenchyma to be the same in each group. The gas exchanging surface areas were also the same. Dry lung weight, DNA, and protein per lung were decreased in the offspring of hypoxic mothers compared to the two other groups. The issue of whether the offspring of the hypoxic mothers should be regarded as having specific hypoplasia because of diminished cell number is discussed.

Animals↗
PubMed1988

Primary invasive carcinoma of the vagina.

A retrospective study of 29 patients with invasive carcinoma of the vagina was completed at The Milton S. Hershey Medical Center, Pennsylvania State University, for a ten-year period from 1976-1986. The overall incidence was 1.3% of all gynecologic malignancies. Twenty-four patients (83%) had squamous cell carcinoma and five (17%) had adenocarcinoma. Squamous cell carcinoma was most commonly located in the upper anterior and lateral vaginal vaults, whereas adenocarcinoma was found more often in the lower anterior and lateral vaginal vaults. The majority of the patients (96%) were managed by a combination of whole-pelvis irradiation and brachytherapy. Twenty-four percent of the patients had a recurrence in the vagina only, indicating the need for better local control. The overall survival rate was 48%. Patients with previous hysterectomy were more likely to develop serious treatment-related complications.

Adenocarcinoma↗
PubMed1987

Left-handed DNA in vivo.

Left-handed DNA is shown to exist and elicit a biological response in Escherichia coli. A plasmid encoding the gene for a temperature-sensitive Eco RI methylase (MEco RI) was cotransformed with different plasmids containing inserts that had varying capacities to form left-handed helices or cruciforms with a target Eco RI site in the center or at the ends of the inserts. Inhibition of methylation in vivo was found for the stable inserts with the longest left-handed (presumably Z) helices. In vitro methylation with the purified MEco RI agreed with the results in vivo. Supercoil-induced changes in the structure of the primary helix in vitro provided confirmation that left-handed helices were responsible for this behavior. The presence in vivo of left-handed inserts elicits specific deletions and plasmid incompatibilities in certain instances.

Cloning, Molecular↗
PubMed1987

Reaction conditions affect the specificity of bromoacetaldehyde as a probe for DNA cruciforms and B-Z junctions.

The reaction of bromoacetaldehyde (BAA) was investigated further with recombinant plasmids containing tracts of (CG)16, in pRW756, or (CA)32, in pRW777, which adopt left-handed Z-structures under the influence of negative supercoiling. The cruciform structures adopted by the inverted repeat sequences near the replication origins of the pBR322 vectors served as internal controls for the number of unpaired bases. The extent of reaction with the B-Z junctions and the cruciforms was dependent on the reaction and analysis conditions, the method of preparation of BAA, ionic conditions, and the amount of negative supercoiling. In contrast to the previous results of Kang and Wells, B-Z junctions in addition to cruciforms do react with BAA. However, more forcing conditions are required to detect this reaction since B-Z junctions appear to be less reactive than the single stranded loops of cruciforms. The site of reaction with DNA was readily mapped with high precision at the nucleotide level. Also, a simple method is described for determining the concentration of BAA as well as its intrinsic reactivity in a given ionic medium.

Acetaldehyde↗
PubMed1987

Specificity of monoclonal anti-Z-DNA antibodies from unimmunized MRL/Mp-lpr/lpr mice.

Antibodies reactive with left-handed Z-DNA arise spontaneously in the sera of patients with SLE and rheumatoid arthritis and in autoimmune MRL mice. However, the precise specificity of these autoantibodies has not been established. In this report, we have characterized four monoclonal anti-Z-DNA antibodies from unimmunized MRL/Mp-lpr/lpr mice that do not cross-react with B-DNA and can discriminate between different types of left-handed helices. Two of the monoclonal antibodies (Za and Zi) behaved similarly in that they bound to two forms of Z-DNA (Br-poly(dG-dC).poly(dG-dC) and AAF-poly(dG-dC).poly(dG-dC) but not to two other Z-form DNA (poly(dG-5BrdC).poly(dG-5BrdC) or poly(dG-5MedC).poly(dG-5MedC)). Neither antibody (Za or Zi) bound significantly to B-DNA or to denatured DNA. A third antibody (Ze) exhibited similar binding characteristics for the Z-DNA preparations, but also recognized denatured DNA. In contrast, a fourth antibody (3-7.3) bound preferentially to poly(dG-5BrC).poly(dG-5BrdC) in Z conformation. These results provide the first evidence for anti-Z-DNA autoantibodies in autoimmune mice that do not cross-react with native or denatured DNA and indicate that these antibodies exhibit considerable heterogeneity in their fine binding specificity.

Animals↗
PubMed1987

Use of second-look laparotomy in the management of patients with ovarian epithelial malignancies.

Between June 1976 and January 1986, 94 evaluable patients with stage I-IV disease underwent second-look laparotomy as part of their treatment for ovarian epithelial carcinomas. Stage and residual tumor size after initial debulking surgery demonstrated a significant association with absence of disease at reexploration. Forty-nine patients (52%) had no evidence of disease at second-look laparotomy. Thirty patients (32%) had macroscopic residual tumor, and 15 patients (16%) had microscopic disease at reexploration. Patients with a negative second-look laparotomy had an excellent prognosis; uncorrected 2- and 5-year survival rates exceed 90%. None of the patients with stage I or II disease developed recurrent tumor after a negative second-look laparotomy. However, 7 of the 25 (28%) patients with stage III disease and a negative second-look have demonstrated recurrent carcinomas. Recurrences were documented from 15.4 to 51.7 months after second-look laparotomy and were located within the abdominal cavity. Life table methods demonstrated improved survival for patients with microscopic disease as compared to those with gross tumor at second-look survey. Both groups had similar mean patient ages and tumor stage distributions. Patients with microscopic residual disease had uncorrected 2- and 5-year survival rates of 76 and 64%. The 2-year uncorrected survival rate for patients with gross tumor at second-look laparotomy was 25%. Thirty patients with macroscopic disease at second-look laparotomy underwent a repeat attempt at tumor debulking. Seventeen patients completed second-look surgery with residual disease less than 1 cm in maximum dimensions. Life table methods demonstrated improved survival when residual disease was less than 1 cm. Regardless of residual tumor size after reexploration, patients with gross tumor had a worse survival than those with microscopic disease.

Adult↗
PubMed1986

Laxative phosphate poisoning: pharmacokinetics of serum phosphorus.

Despite the frequency of acute poisoning in normal children by oral or rectal phosphosoda laxatives, the rate of clearance of the resultant high level of phosphorus and the rationale for therapy are defined incompletely. Pharmacokinetic analysis has been made of plasma inorganic phosphate (Pi) in an infant after ingestion of phosphosoda laxative and of data reported for four comparable poisonings in healthy infants to provide a nomogram which predicts the decline in Pi in paediatric phosphate poisoning. Clearance of Pi is exponential; it directly correlates with and approaches the glomerular filtration rate. After single oral or rectal overdoses, plasma Pi at diagnosis is 4-20 mmol/l and has a half-life of 5-11 h that appears independent of therapy. The time for plasma Pi to return to normal can be calculated from the initial Pi as t = (ln 5/Pi)/0.1292. Neuromuscular and cardiac abnormalities relate to the low serum calcium; the increase of total serum calcium during recovery from phosphate poisoning is linear but is accelerated by intravenous (i.v.) calcium salt. Continued i.v. calcium therapy may be required since restoration of plasma calcium is often delayed.

Calcium↗
PubMed1985

Combined prostaglandin therapy and ductal formalin infiltration in neonatal pulmonary oligemia.

Prostaglandins and ductal formalin infiltration, singly and together, have been used in efforts to improve pulmonary flow in very ill newborn infants with right ventricular outflow tract obstruction. To evaluate the efficacy of concurrent use of prostaglandins and ductal formalin infiltration, we have reviewed our experience with 25 infants with right ventricular outflow tract obstruction and prostaglandin-ductal formalin infiltration therapy. Prostaglandin therapy was begun 22 +/- 21 hours (range 20 to 93 hours) before and was continued 20 +/- 18 hours (range 0 to 62 hours) following ductal formalin infiltration; prostaglandin administration was initiated at a dose of 0.05 to 0.1 microgram/kg/min and tapered postoperatively. Clinical cyanosis was diminished in 20 of 25 infants (80%) postoperatively. Systemic arterial pH and oxygen saturation both improved following prostaglandin-ductal formalin infiltration therapy from 7.35 to 7.41 (p less than 0.001) and from 35.7 to 50.3 (p less than 0.001), respectively. Persistent ductal patency (mean 219 +/- 191 days) was observed in 17 survivors of the early postoperative period (more than 14 days). Two of five infants who died within 14 days of operation had a widely patent ductus with resultant progressive congestive heart failure. The other three infants died as a result of operative technical problems, dysrhythmias, and thrombotic ductal closure, respectively. No correlation was observed between duration of ductus patency and operatively determined size of ductus, total prostaglandin dose, or duration of prostaglandin infusion. Secondary operative intervention was delayed by 92 +/- 74 days with prostaglandin-ductal formalin infiltration therapy; thus prostaglandin-ductal formalin infiltration therapy may have a role in selected neonates with right ventricular outflow tract obstruction.

Alprostadil↗
PubMed1984

HhaI methylase and restriction endonuclease as probes for B to Z DNA conformational changes in d(GCGC) sequences.

The capacity of the modification methylase (MHhaI) and restriction endonuclease (HhaI) form Haemophilus haemolyticus to methylate and cleave, respectively, recognition sites which are in right-handed B or left-handed Z structures was determined in vitro. Plasmids containing tracts of (dC-dG) as well as numerous individual d(GCGC) sites distributed around the vector were studied. Negative supercoiling was used to convert the (dC-dG) tracts (approximately 30 bp in length) from a right-handed to a left-handed conformation. (Methyl-3H)-SAM was used to localize and quantitate modified d(GCGC) recognition sites, whereas cleavage by HhaI was used to detect unmethylated sites. In the left-handed Z-form, the (dC-dG) blocks were not methylated by MHhaI and not cleaved by HhaI. A two-dimensional gel analysis of a family of 33 topoisomers treated with MHhaI revealed that the lack of methylation in the (dC-dG) blocks was directly correlated to the supercoil-induced B to Z transition in these segments. These results are significant with respect to enzyme-DNA interactions in general and provide the basis for using HhaI and MHhaI as probes for different DNA structures and conformational transitions under physiological conditions.

Base Sequence↗