PubMed Health⌕ Search

Biomedical subjects

J A Thompson

Publications and source records attributed to J A Thompson.

At least 19 recordsLinked to original sources
PubMed1992

Construction and characterisation of a yeast artificial chromosome library containing three haploid maize genome equivalents.

We have constructed a yeast artificial chromosome (YAC) library using high-molecular-weight DNA prepared from agarose-embedded leaf protoplasts of the maize inbred line UE95. This library contains 79,000 clones with an average insert size of 145 kb and should therefore represent approximately three haploid genome equivalents. The library is organised as an ordered array in duplicate microtitre plates. Forty-one pools of DNA from 1920 individual clones have been prepared for rapid screening of the library by the polymerase chain reaction (PCR). Using this approach, together with conventional colony hybridisation, we have been able to identify between one and eight positive clones for every probe used.

Chloroplasts↗
PubMed1992

Characterization of murine carcinoembryonic antigen gene family members.

The carcinoembryonic antigen (CEA) is a human tumor marker whose gene belongs to a family with more than 20 members. This gene family codes for a group of proteins with in vitro cell adhesion properties and for a group of abundantly expressed pregnancy-specific glycoproteins (PSG) with unknown functions. As a basis for in vivo functional studies, we have started to analyze the murine CEA gene family and have identified five new members (Cea-2 to Cea-6). cDNA clones were isolated for Cea-2, Cea-3, and Cea-6. The deduced amino acid sequences of Cea-2 and Cea-6 indicate three IgV-like (N), followed by one IgC-like (A) domain (N1-N2-N3-A). We have also partially characterized the Cea-2 gene and two additional ones, Cea-4 and Cea-5. Cea-2 and Cea-4 are separated by only 16 kb, suggesting a close linkage of murine CEA-related genes, as found for the human CEA gene family. Cea-5 was located to the proximal region of mouse Chromosome (Chr) 7, which is syntenic to part of human Chr 19, containing the human CEA gene family cluster. Cea-2, Cea-3, and a Cea-4-like gene are differentially transcribed in the placenta during pregnancy, but not in other organs tested. This expression pattern strongly suggests that they represent counterparts of the human PSG subgroup members, despite the presence of multiple IgV-like domains, a feature not found for human PSGs. The more distantly related Cea-5 seems to be ubiquitously expressed. The putative promoter region of Cea-2 lacks typical TATA- or CAAT-boxes, but contains other conserved motifs that could play a role in the initiation of transcription.

Amino Acid Sequence↗
PubMed1992

A comparison of methods for sample clean-up prior to quantification of metal-binding proteins.

1. The recovery of rabbit metallothionein and metallothionein-like proteins has been examined under different conditions. 2. After heat or ethanol denaturation, recovery of rabbit MT-II was quantitative. 3. Recovery of rabbit MT was not affected by the presence or absence of dithiothreitol (DTT) after heat treatment. However, recovery from ethanolic solution decreased in buffers that did not contain the antioxidant. 4. Acetone precipitation of rabbit MT resulted in lower yields which approached 90% only in the presence of DTT. 5. Recovery of metallothionein-like proteins from cytosols of the hepatopancreas of the tanner crab, Chionoecetes bairdi, were examined using pulse polarography and HPLC. Relative to heat denaturation, ethanol and acetone yielded recoveries of 66 and 28%, respectively, in the presence of DTT. However, acetone did yield a solution which contained less extraneous protein of molecular mass greater than 43 kDa than heat denaturation. 6. We concluded that heat denaturation is the preferred treatment for quantitative recovery of metal-binding proteins. Acetone precipitation is useful for the purification of MT.

Acetone↗
PubMed1992

Increased morbidity with increased pulmonary albumin flux in sepsis-related adult respiratory distress syndrome.

OBJECTIVE: To determine the feasibility of utilizing a scintigraphic technique to differentiate patients with adult respiratory distress syndrome due to sepsis syndrome from control volunteers and patients with congestive heart failure. Gamma scintigraphy was compared with chest roentgenograms to predict mortality rate and morbidity in adult respiratory distress syndrome (ARDS) patients. DESIGN: Prospective study. SETTING: University hospital ICUs. PATIENTS: Thirty-five control volunteers, 19 patients with congestive heart failure, 30 patients with a diagnosis of sepsis. MEASUREMENTS AND MAIN RESULTS: All patients were infused iv with technetium 99m-labeled albumin and underwent computerized gamma-scintigraphic analysis with a portable gamma camera. Lung-to-heart ratio of tracer was calculated and expressed as the slope index. Increase in slope index indicated increased pulmonary albumin flux. Slope index was no different in controls compared with congestive heart failure patients, unless the pulmonary artery occlusion pressure (PAOP) was greater than 30 mm Hg. Patients with a diagnosis of sepsis had an overall increased slope index compared with the other groups. A subgroup of patients in the septic group had a normal slope index. Septic patients with an increased slope index had a significantly (p less than .01) longer duration of mechanical ventilation (36 +/- 5 vs. 7 +/- 1 days), spent longer in the ICU (67 +/- 9 vs. 11 +/- 1 days), and had a longer hospital stay (113 +/- 20 vs. 35 +/- 5 days) than septic patients with a normal slope index. CONCLUSIONS: Gamma scintigraphy successfully differentiated between control volunteers and patients with congestive heart failure with PAOP less than 30 mm Hg from patients with sepsis-induced ARDS. Although all of the patients with a clinical diagnosis of septic ARDS had similar impairments in oxygenation and chest roentgenograms, those patients with a significantly increased pulmonary albumin flux (greater than 2 SD above control mean) had a markedly increased morbidity.

Adult↗
PubMed1992

Prolonged continuous intravenous infusion interleukin-2 and lymphokine-activated killer-cell therapy for metastatic renal cell carcinoma.

PURPOSE: Two consecutive protocols of continuous intravenous (CIV) infusion interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells were carried out in patients with metastatic renal cell carcinoma (RCC) to determine the response rate and toxicity. PATIENTS AND METHODS: In both protocols, patients received induction IL-2 at 6 x 10(6) U/m2/d on days 1 to 5, and underwent leukapheresis on days 7 to 9 at the peak of rebound lymphocytosis. LAK cells were generated by a 5-day incubation with IL-2 at 1,000 U/mL, and were infused on days 12 to 14. For the first 20 patients (protocol A), maintenance IL-2 was administered at 6 x 10(6) U/m2/d on days 12 to 16. On the assumption that less IL-2 might be required to maintain rather than to induce LAK activity, and that a longer duration of maintenance IL-2 might enhance LAK survival and function in vivo, the protocol for the subsequent 22 patients (protocol B) was altered so that the maintenance phase consisted of a lower dose of IL-2 (2 x 10(6) U/m2/d) administered for a longer period of time (days 10 to 20). RESULTS: In protocol A, there were two complete responses (CRs) and three partial responses (PRs), for a total response rate of 25%. One PR was surgically converted into a CR. The durations of the CRs are 36+, 18+, and 18+ months. Hypotension and capillary leak were most severe during maintenance, which limited the median duration of maintenance IL-2 to 4 days. In protocol B, no patient experienced severe hypotension, and the median duration of maintenance IL-2 was 9 days. Two patients exhibited a CR and seven a PR, for a total response rate of 41%. Two PRs were surgically converted to CRs. The durations of CR are 14+, 9+, 6+, and 5+ months. In both protocols, the CIV induction regimen resulted in marked rebound lymphocytosis (mean, 11,097/microL) and LAK-cell yield (mean, 18.1 x 10(10)). The cumulative response rate was 14 of 42 patients, or 33% (95% confidence interval, 19% to 47%). CONCLUSION: These results demonstrate that both protocols of CIV IL-2 plus LAK cells have substantial antitumor activity, and that a longer maintenance phase of IL-2 at a lower dose is associated with significantly less toxicity without a loss of therapeutic efficacy.

Adult↗
PubMed1992

Orthotic therapy in the management of osteoarthritis.

The authors evaluate the use of orthoses as a primary therapeutic means in the long-term management of patients with osteoarthritis of the foot and ankle. A comparison of the amount of pain relief experienced by 64 subjects (mean age 63 years) with different treatment regimens for osteoarthritis was made to determine the role orthoses played in helping to reduce or eliminate pain. One hundred percent of the subjects wearing orthoses only for relief of pain had a statistically significant longer period of pain relief than those on nonsteroidal anti-inflammatory drugs. Fifty-five percent of the subjects using orthoses and nonsteroidal anti-inflammatory drug therapy also had a statistically significant longer period of pain relief than those receiving nonsteroidal anti-inflammatory drug therapy only.

Adult↗
PubMed1991

Differential expression in Escherichia coli of the alpha and beta forms of heparin-binding acidic fibroblast growth factor-1: potential role of RNA secondary structure.

Synthetic DNA fragments encoding the entire open-reading frame of human heparin-binding growth factor-1 (HBGF-1 beta) and its NH2-terminal truncated form (HBGF-1 alpha) were constructed. When both constructs were expressed in Escherichia coli under control of the trp-lac promoter, biologically active HBGF-1 alpha, but not HBGF-1 beta was produced in high yield. However, high level expression of HBGF-1 beta was obtained using the T7 polymerase expression vector. Computer analysis of HBGF-1 beta predicts the potential for the formation of exaggerated RNA secondary structure near the translation initiation codon and this could be implicated in contributing to the poor translation of HBGF-1 beta under the trp-lac promoter.

Base Sequence↗
PubMed1991

Toxicity and immunomodulatory effects of interleukin-2 after autologous bone marrow transplantation for hematologic malignancies.

Autologous bone marrow transplantation (ABMT) for advanced hematologic malignancies is associated with high relapse rates. Interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells represent a potentially non-cross-resistant therapeutic modality that might prevent or delay relapses if used early after ABMT at a time when the tumor burden is minimal. However, high-dose chemoradiotherapy and ABMT might increase patients' susceptibility to IL-2 toxicity, and might interfere with immunologic responses to IL-2 in vivo. Therefore, to determine safety, tolerance, and immunomodulatory effects of IL-2 therapy early after ABMT, IL-2 was administered by continuous intravenous infusion to 16 patients 14 to 91 days (median, 33) after ABMT for acute leukemia, lymphoma, or multiple myeloma. Patients were sequentially assigned to escalating IL-2 "induction" doses (0.3 to 4.5 x 10(6) U/m2/d, days 1 to 5), and all patients received a nonescalating IL-2 "maintenance" dose (0.3 x 10(6) U/m2/d, days 12 to 21). Most patients exhibited mild to moderate fever, nausea, diarrhea, and/or skin rash with IL-2 infusions. The maximum tolerated "induction" dose was 3.0 x 10(6) U/m2/d; dose-limiting toxicities were hypotension and thrombocytopenia. All toxicities reversed on stopping the IL-2 infusions, and all patients completed "maintenance." Postinfusion lymphocytosis was exhibited by patients at all IL-2 dose levels. With the higher IL-2 doses, increased percentages of patients' PBMC expressed CD16 and CD56, with augmented lysis of K562 and Daudi, reflecting the induction of natural killer and circulating LAK effector activities. Increased LAK precursor activity was exhibited by patients at all IL-2 dose levels. Thus, the IL-2 therapy regimen was safely tolerated after ABMT, and pronounced immunomodulatory effects were observed with the higher IL-2 doses. These studies support the planned use of IL-2 and LAK cells after ABMT in an attempt to reduce relapses of advanced hematologic malignancies.

Adolescent↗
PubMed1991

Carcinoembryonic antigen gene family: molecular biology and clinical perspectives.

The carcinoembryonic antigen (CEA) gene family belongs to the immunoglobulin super-gene family and can be divided into two main subgroups based on sequence comparisons. In humans it is clustered on the long arm of chromosome 19 and consists of approximately 20 genes. The CEA subgroup genes code for CEA and its classical crossreacting antigens, which are mainly membrane-bound, whereas the other subgroup genes encode the pregnancy-specific glycoproteins (PSG), which are secreted. Splice variants of individual genes and differential post-translational modifications of the resulting proteins, e.g., by glycosylation, indicate a high complexity in the number of putative CEA-related molecules. So far, only a limited number of CEA-related antigens in humans have been unequivocally assigned to a specific gene. Rodent CEA-related genes reveal a high sequence divergence and, in part, a completely different domain organization than the human CEA gene family, making it difficult to determine individual gene counterparts. However, rodent CEA-related genes can be assigned to human subgroups based on similarity of expression patterns, which is characteristic for the subgroups. Various functions have been determined for members of the CEA subgroup in vitro, including cell adhesion, bacterial binding, an accessory role for collagen binding or ecto-ATPases activity. Based on all that is known so far on its biology, the clinical outlook for the CEA family has been reassessed.

Amino Acid Sequence↗
PubMed1991

An improved microcomputer program for finding gene- or gene family-specific oligonucleotides suitable as primers for polymerase chain reactions or as probes.

We present here an easy-to-use computer program which finds oligonucleotides suitable as primers in polymerase chain reactions (PCR) or as probes for hybridization. In contrast to other programs used for this purpose, the additional advantage of this one is the possibility of directly detecting gene- as well as gene family-specific oligonucleotides. For this purpose, up to 200 different DNA sequences, of maximally 65,000 nucleotides each, can be scanned in a single search to ensure either single or multiple gene binding of the PCR primers or probes. Specific oligonucleotides for genes carrying internal repetitions and for single genes belonging to a set of highly conserved genes can also be detected. Many parameters such as exclusion of simple sequences, which are known to be highly repeated throughout various genomes or regions of stable secondary structures in both primer-primer and primer-template, can be taken into consideration and avoided. Furthermore, the G + C content and the length of the oligonucleotides can be changed in a broad range by the user.

Animals↗
PubMed1990

Cloning of a carcinoembryonic antigen gene family member expressed in leukocytes of chronic myeloid leukemia patients and bone marrow.

The carcinoembryonic antigen (CEA) gene family belongs to the immunoglobulin superfamily and can be subdivided into the CEA and pregnancy-specific glycoprotein subgroups. The basic structure of the encoded proteins consists of, in addition to a leader, one IgV-like and 2, 3, or 6 IgC-like domains. These domains are followed by varying COOH-terminal regions responsible for secretion, transmembrane anchoring, or insertion into the membrane by a glycosyl phosphatidylinositol tail. Here we report on the characterization of CGM6, a new member of the CEA gene subgroup, by complementary DNA cloning. The deduced coding region comprises 349 amino acids and consists of a leader, one IgV-like, two IgC-like domains, and a hydrophobic region, which is replaced by a glycosyl phosphatidylinositol moiety in the mature protein. CGM6 transcripts were only found thus far in leukocytes of chronic myeloid leukemia patients, in normal bone marrow, and in marginal amounts in normal granulocytes. The CGM6 gene product might, therefore, represent a myeloid marker. Analyses of CGM6 protein-expressing HeLa transfectants with monoclonal antibodies strongly indicate that the CGM6 gene codes for the CEA family member NCA-95.

Antigens, Neoplasm↗
PubMed1990

Identification and characterization of an adenovirus 2 major late promoter CAP sequence DNA-binding protein.

DNase I footprint analysis of the core adenovirus 2 (Ad2) major late promoter (MLP) has revealed distinct patterns of protection corresponding to the assembly of transcription components during transcriptional initiation (VanDyke, M. W., Sawadogo, M., and Roeder, R. G. (1989) Mol. Cell Biol. 7, 3371-3379). By using partially purified transcription factors, DNase I protection over the TATA box element and the CAP sequence was attributed to the binding of a single factor, TFIID. We have determined, however, that protection of the CAP region results from the binding of a novel factor, designated CAP-site binding factor (CBF), which is chromatographically and functionally distinct from TFIID. DNase I footprint analysis and gel electrophoresis mobility shift competition assays confirm that distinct polypeptides bind to the Ad2 MLP upstream promoter sequence, TATA box, and CAP sequences. When the CAP sequence is mutated, transcriptional activity of the Ad2 MLP is reduced both in vitro and in vivo. The decrease in transcriptional activity correlates with decreased CBF binding activity. Nuclear extracts depleted of CBF also exhibit reduced Ad2 MLP transcriptional activity. The addition of DNA affinity purified CBF, free of TFIID or major late transcription factor, restores the activity to control levels.

Adenoviruses, Human↗