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Biomedical subjects

C Carlson

Publications and source records attributed to C Carlson.

At least 19 recordsLinked to original sources
PubMed1998

Technetium-99m DTPA aerosol contamination in lung ventilation studies.

UNLABELLED: Contamination of working areas by 99mTc DTPA aerosol is of concern to nuclear medicine technologists. This study sought to determine the extent of 99mTc DTPA contamination to technologists, and to localize sources of aerosol leakage so that methods could be identified that would minimize contamination. METHODS: Fifty to eighty millicuries 99mTc DTPA, diluted to a volume of 4-5 ml with normal saline, were injected into the nebulizing chamber of two commercially available inhalation aerosol systems. The patient's nostrils were clamped and a damp washcloth was wrapped around the patient's mouth. An alcohol swab was placed in the exit port of the exhaust filter in each delivery system, and the technologist involved wore a face mask during the inhalation phase. The patient breathed DTPA-labeled aerosol by mouth until the counting rate in the lungs was four times greater than the counting rate from the pulmonary perfusion phase. Connecting joints of the delivery system were then wipe tested. Last, a Geiger-Mueller detector (pancake probe) was used to survey all device components. Readings above 0.05 mR/hr were considered contaminated. RESULTS: The patient was the greatest source of leakage as determined by the damp washcloth, followed by the joints of the tubes of the delivery system and, finally, the system's exhaust filter. Contamination readings from face masks worn by technical personnel during the lung ventilation studies were slightly greater than 0.05 mR/hr. CONCLUSION: The findings support trace levels of contamination to both the technologist and room while performing 99mTc DTPA aerosol ventilation studies. Comparative data using the two delivery systems revealed little difference in sources of leakage and little variation in contamination measurements.

Aerosols↗
PubMed1997

Characterization and mutation analysis of goosecoid-like (GSCL), a homeodomain-containing gene that maps to the critical region for VCFS/DGS on 22q11.

Velocardiofacial syndrome (VCFS) is a developmental disorder characterized by conotruncal heart defects, craniofacial anomalies, and learning disabilities. VCFS is phenotypically related to DiGeorge syndrome (DGS) and both syndromes are associated with hemizygous 22q11 deletions. Because many of the tissues and structures affected in VCFS/DGS derive from the pharyngeal arches of the developing embryo, it is believed that haploinsufficiency of a gene(s) involved in embryonic development may be responsible for its etiology. A homeodomain-containing gene, Goosecoidlike (GSCL), has been recently described, and it resides in the critical region for VCFS/DGS on 22q11. GSCL is related to the Goosecoid gene (GSC) in both sequence of the homeodomain and genomic organization. Gsc in the mouse is expressed during early and midembryogenesis and is required for craniofacial rib, and limb development. The chick homolog of GSCL, termed GSX, is expressed during early chick embryogenesis. We detected GSCL expression in human embryos and biphasic expression in mouse embryos. It is possible that the vertebrate GSCL gene is also required for embryonic development. Due to its location in the critical region on 22q11, GSCL is an excellent candidate gene for VCFS/DGS. The vertebrate GSC protein has the same DNA binding specificity as the Drosophila morphogen, bicoid. Upon examination of the putative GSCL promoter, we found three sequence elements with an exact match to the reverse complement of the bicoid DNA recognition motif, suggesting that GSC, or possibly GSCL itself, regulates the transcription of GSCL. Sequence analysis of the putative promoter and the coding region of GSCL was performed on the DNA template from 17 VCFS patients who did not have a detectable 22q11 deletion to identify mutations. We did not detect a mutation in this set of VCFS patients. A polymorphism was detected in codon 47 of exon 1.

Abnormalities, Multiple↗
PubMed1997

Expression, purification, and characterization of a soluble form of human cytomegalovirus glycoprotein B.

The human cytomegalovirus glycoprotein B gene (gB; gpUL55) was truncated at amino acid 692 and recombined into Autographa californica nuclear polyhedrosis virus (baculovirus). Infection of insect cells with the recombinant baculovirus resulted in high-level expression and secretion of the truncated gB protein (gB-S) into the culture medium. Purification of gB-S by monoclonal antibody affinity chromatography yielded a protein of ca. 200 kDa. Characterization of the 200-kDa purification product indicated that the recombinant gB protein retained many structural and functional features of the viral gB. Comparison of electrophoretic migration patterns in reduced versus nonreduced protein samples and immune blotting analysis with antibodies specific for the amino or carboxy-terminus of gB demonstrated that the recombinant protein was composed of disulfide linked 69 kDa amino terminal and 35-kDa carboxy-terminal fragments. In addition, recognition of the 200-kDa gB-S by a conformational-dependent, oligomer-specific monoclonal antibody suggested that gB-S was properly folded and dimeric. Like the viral gB, gB-S had heparin binding ability. One heparin binding site was found to reside within the 35-kDa carboxy-terminal fragment (aa 492-692). Heparin binding was abolished when gB-S was denatured. These data suggest that gB contains a novel heparin binding motif that is at least partially conformational dependent.

Cytomegalovirus↗
PubMed1997

Molecular definition of 22q11 deletions in 151 velo-cardio-facial syndrome patients.

Velo-cardio-facial syndrome (VCFS) is a relatively common developmental disorder characterized by craniofacial anomalies and conotruncal heart defects. Many VCFS patients have hemizygous deletions for a part of 22q11, suggesting that haploinsufficiency in this region is responsible for its etiology. Because most cases of VCFS are sporadic, portions of 22q11 may be prone to rearrangement. To understand the molecular basis for chromosomal deletions, we defined the extent of the deletion, by genotyping 151 VCFS patients and performing haplotype analysis on 105, using 15 consecutive polymorphic markers in 22q11. We found that 83% had a deletion and >90% of these had a similar approximately 3 Mb deletion, suggesting that sequences flanking the common breakpoints are susceptible to rearrangement. We found no correlation between the presence or size of the deletion and the phenotype. To further define the chromosomal breakpoints among the VCFS patients, we developed somatic hybrid cell lines from a set of VCFS patients. An 11-kb resolution physical map of a 1,080-kb region that includes deletion breakpoints was constructed, incorporating genes and expressed sequence tags (ESTs) isolated by the hybridization selection method. The ordered markers were used to examine the two separated copies of chromosome 22 in the somatic hybrid cell lines. In some cases, we were able to map the chromosome breakpoints within a single cosmid. A 480-kb critical region for VCFS has been delineated, including the genes for GSCL, CTP, CLTD, HIRA, and TMVCF, as well as a number of novel ordered ESTs.

Abnormalities, Multiple↗
PubMed1997

Molecular analysis of velo-cardio-facial syndrome patients with psychiatric disorders.

Velo-cardio-facial syndrome (VCFS) is characterized by conotruncal cardiac defects, cleft palate, learning disabilities, and characteristic facial appearance and is associated with hemizygous deletions within 22q11. A newly recognized clinical feature is the presence of psychiatric illness in children and adults with VCFS. To ascertain the relationship between psychiatric illness, VCFS, and chromosome 22 deletions, we evaluated 26 VCFS patients by clinical and molecular biological methods. The VCFS children and adolescents were found to share a set of psychiatric disorders, including bipolar spectrum disorders and attention-deficit disorder with hyperactivity. The adult patients, >18 years of age, were affected with bipolar spectrum disorders. Four of six adult patients had psychotic symptoms manifested as paranoid and grandiose delusions. Loss-of-heterozygosity analysis of all 26 patients revealed that all but 3 had a large 3-Mb common deletion. One patient had a nested distal deletion and two did not have a detectable deletion. Somatic cell hybrids were developed from the two patients who did not have a detectable deletion within 22q11 and were analyzed with a large number of sequence tagged sites. A deletion was not detected among the two patients at a resolution of 21 kb. There was no correlation between the phenotype and the presence of the deletion within 22q11. The remarkably high prevalence of bipolar spectrum disorders, in association with the congenital anomalies of VCFS and its occurrence among nondeleted VCFS patients, suggest a common genetic etiology.

Abnormalities, Multiple↗
PubMed1996

Strategies for manipulating apoptosis for cancer therapy with tumor necrosis factor and lymphotoxin.

Tumor necrosis factor (TNF) and lymphotoxin (LT), initially described as tumoricidal proteins, may be useful as adjuncts in cancer therapy. Treatment with TNF or LT was found to protect cells and animals against damage mediated by radiation or cytotoxic anticancer drugs. By contrast, tumor cells treated with TNF or LT were sensitized to these insults. We present a model in which TNF or LT induces both the synthesis of "protective" proteins such as manganous superoxide dismutase (MnSOD) and the activation of "killing" proteins, such as proteases, depending on the level of the inducing signal. Although the p55-TNF/LT receptor is structurally related to the Fas receptor, they can each signal apoptosis by distinct pathways. Furthermore, activation of both receptors acts synergistically in stimulating apoptosis.

Animals↗
PubMed1996

Identifying DNA polymorphisms in human TCRA/D variable genes by direct sequencing of PCR products.

The T-cell receptor (TCR) is a highly variable molecule composed of two polypeptide chains that recognize antigenic peptides in the context of major histocompatibility complex (MHC) molecules. In this study, we describe a sequence-based search for germline polymorphisms in the variable (V) gene segments of the human TCRA/D locus. Thirty different V gene segments were amplified from six to eight unrelated individuals and sequenced from low melting point agarose. Twenty-seven polymorphisms were identified in 15 V gene segments. These polymorphisms are mainly single nucleotide substitutions, but an insertion/deletion polymorphism and a single dinucleotide repeat with variable length were also seen. Of the 15 sequence variations found in the coding regions, six are silent and nine encode amino acid changes. All of the amino acid changes are found at non-conserved residues, frequently in the hypervariable regions, where they may influence MHC and/or peptide recognition. Therefore, it is possible that germline variations in TCR genes could influence an individual's immune response, and may also contribute to susceptibility to diseases such as autoimmunity.

Amino Acid Sequence↗
PubMed1996

The influence of cutaneous tissue afferents on masticatory pain-pressure thresholds.

Pain-pressure thresholds are routinely used in orofacial pain research to record tenderness in masticatory muscles. This method is employed to stimulate deep tissue afferents, which are thought to be at least partially responsible for pain in temporomandibular disorders. Like other psychophysical measurements, however, this technique must stimulate cutaneous tissues before stimulating deeper tissues. This study examined 39 asymptomatic volunteers to quantify the effect of cutaneous sensory afferents on pain-pressure thresholds. In a randomized, double-blind fashion, pain-pressure thresholds were recorded at four facial sites before and after subjects received intradermal local anesthetic or a dry needle stick. Pain-pressure thresholds were significantly elevated after local anesthetic (P < .0001), suggesting that cutaneous tissues contribute significantly to the pain-pressure threshold. The authors discuss potentially important roles of cutaneous tissues in the assessment of deeper tissues and offer two theories of how the skin may be an important link in the assessment of temporomandibular disorders.

Administration, Cutaneous↗
PubMed1995

Identification, sequence, and transcriptional analysis of lef-3, a gene essential for Orgyia pseudotsugata baculovirus DNA replication.

Using a transient complementation assay for DNA replication of an origin-containing reporter plasmid, a 2.4-kb region (m.u. 48.3-50.1) of the Orgyia pseudotsugata multinucleocapsid nuclear polyhedrosis virus (OpMNPV) genome was identified that contains a gene essential for OpMNPV DNA replication. This region was sequenced and open reading frames were identified. Replication assays using subclones from this region identified a gene called late expression factor 3 (lef-3), as the essential replication gene. Transcriptional mapping using both Northern blot and S1 nuclease protection assays demonstrated that lef-3 was expressed as an early gene with a major transcript of 1.7 kb in length. OpMNPV lef-3 encodes a protein with a predicted molecular weight of 42.6 kDa (373 amino acids) and exhibits 41% amino acid sequence identity with its homolog in the genome of the Autographa californica MNPV. A pattern of amino acids similar to that found in single-stranded DNA binding proteins is present in the amino-terminus of both OpMNPV and AcMNPV LEF-3.

Amino Acid Sequence↗
PubMed1995

Velo-cardio-facial syndrome: frequency and extent of 22q11 deletions.

Velo-cardio-facial (VCFS) or Shprintzen syndrome is associated with deletions in a region of chromosome 22q11.2 also deleted in DiGeorge anomaly and some forms of congenital heart disease. Due to the variability of phenotype, the evaluation of the incidence of deletions has been hampered by uncertainty of diagnosis. In this study, 54 patients were diagnosed with VCFS by a single group of clinicians using homogeneous clinical criteria independent of the deletion status. Cell lines of these patients were established and the deletion status evaluated for three loci within the commonly deleted region at 22q11.2 using fluorescence in situ hybridization (FISH). In 81% of the patients all three loci were hemizygous. In one patient we observed a smaller interstitial deletion than that defined by the three loci. The phenotype of this patient was not different from that observed in patients with larger deletions.

Abnormalities, Multiple↗
PubMed1995

Peak height variations in automated sequencing of PCR products using Taq dye-terminator chemistry.

Direct sequencing of PCR products using Taq DNA polymerase with dye-labeled dideoxy chain terminators results in traces with uneven peaks. The peak height variations reflect the disproportionate rate of incorporation of deoxynucleotides vs. their analogs, a phenomenon that is highly dependent on the neighboring DNA sequence. Such peak height variations make it difficult to call bases correctly or to interpret whether or not a polymorphism is present. We have systematically examined pairs of sequence-tagged sites that vary at only one nucleotide to determine how a single base change will affect the peak heights of neighboring bases. We have found that the peak height of a particular base can often be predicted from the knowledge of just one or two nucleotides 5'- to the base in question. We have also observed several artifacts that occur consistently in the sequencing traces. These artifacts can be misinterpreted as polymorphisms or can obscure the real peak at that site. The empirically derived trends presented in this report can be utilized profitably when one is editing sequence data or examining them for polymorphisms and mutations.

Coloring Agents↗
PubMed1995

Molecular definition of the 22q11 deletions in velo-cardio-facial syndrome.

Velo-cardio-facial syndrome (VCFS) is a common genetic disorder among individuals with cleft palate and is associated with hemizygous deletions in human chromosome 22q11. Toward the molecular definition of the deletions, we constructed a physical map of 22q11 in the form of overlapping YACs. The physical map covers > 9 cM of genetic distance, estimated to span 5 Mb of DNA, and contains a total of 64 markers. Eleven highly polymorphic short tandem-repeat polymorphic (STRP) markers were placed on the physical map, and 10 of these were unambiguously ordered. The 11 polymorphic markers were used to type the DNA from a total of 61 VCFS patients and 49 unaffected relatives. Comparison of levels of heterozygosity of these markers in VCFS patients and their unaffected relatives revealed that four of these markers are commonly hemizygous among VCFS patients. To confirm these results and to define further the breakpoints in VCFS patients, 15 VCFS individuals and their unaffected parents were genotyped for the 11 STRP markers. Haplotypes generated from this study revealed that 82% of the patients have deletions that can be defined by the STRP markers. The results revealed that all patients who have a deletion share a common proximal breakpoint, while there are two distinct distal breakpoints. Markers D22S941 and D22S944 appear to be consistently hemizygous in patients with deletions. Both of these markers are located on a single nonchimeric YAC that is 400 kb long. The results also show that the parental origin of the deleted chromosome does not have any effect on the phenotypic manifestation.

Abnormalities, Multiple↗
PubMed1994

A targeted chain-termination mutation in the mouse Apc gene results in multiple intestinal tumors.

Germ-line mutations in the human adenomatous polyposis coli (APC) gene result in familial adenomatous polyposis, an autosomal dominant disorder characterized by the early onset of multiple adenomatous polyps in the large bowel with a high likelihood of developing colorectal carcinomas. To understand the role of APC in intestinal tumor formation, we have introduced a chain-termination mutation in the 15th exon of the mouse Apc gene and employed it to modify the endogenous gene by homologous recombination in embryonic stem cells. Mice which are heterozygous for the Apc gene modification progressively develop intestinal tumors in a manner that is similar to that observed in patients with familial adenomatous polyposis and in mice which carry a mutation called multiple intestinal neoplasia (Min). Our results indicate that the Apc gene modification is a critical event in the initiation of intestinal tumor formation and results in an autosomal dominant predisposition toward development of spontaneous colonic and intestinal tumors in mice.

Adenomatous Polyposis Coli↗
PubMed1994

Comparative analysis of human DNA variations by fluorescence-based sequencing of PCR products.

Automated, direct cycle sequencing of purified double-stranded PCR products using Taq polymerase and fluorescently labeled dideoxynucleotide terminators provides a robust and highly reproducible method for identifying DNA sequence variations in sequence-tagged sites. We describe a simple and sensitive strategy that reliably detects the presence of DNA variations when sequencing traces from several different individuals are compared. We also demonstrate the use of this strategy to estimate allele frequencies of single nucleotide substitutions in a population. Taken together, this approach provides an automated method for conducting rapid population studies of candidate gene regions that are in linkage or association with a specific disease and for comparative evolutionary analysis of selected regions of the human genome.

Alleles↗
PubMed1992

The effect of sodium cromoglycate eyedrops compared to the effect of terfenadine on acute symptoms of seasonal allergic conjunctivitis.

A multicentre, group comparative open study was carried out on 68 patients to compare the effects of 2% sodium cromoglycate eyedrops and an oral antihistamine, terfenadine, on acute symptoms of seasonal allergic conjunctivitis. The study was continued for one week after the onset of acute symptoms. Both medications were equally efficient in reducing symptoms during the first hour of observation. During the one-week follow-up both medications reduced symptoms to a low level, and both medications were equally effective for allergic symptoms, except that terfenadine was more effective in reducing the watering of eyes.

Acute Disease↗
PubMed1991

Problems affecting the liquid chromatographic quantitation of chlorhexidine digluconate in ophthalmic solutions.

A liquid chromatogrpahic (LC) assay was recommended by the Food and Drug Administration of the United States for the uptake and release study of chlorhexidine digluconate (CHDG) in ophthalmic solutions by contact lenses. The results from this and other reversed-phase LC assays of CHDG were inaccurate when the working standard and sample solution matrices were different. The error was caused by binding of the analyte onto the container surface and LC column packings. The loss of chlorhexidine due to binding was dependent upon, and very sensitive to, the counter ions in the sample solutions. Relative to water solutions of CHDG, solutions containing chloride, thiosulphate and edetate reduced the loss of the analyte, while solutions containing borate enhanced the loss. To assay CHDG reliably with reversed-phase LC, the media of the working standard and the sample solutions should be closely matched.

Chlorhexidine↗