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Biomedical subjects

C Abbott

Publications and source records attributed to C Abbott.

At least 55 records · Page 3Linked to original sources
PubMed1991

Disruption of the LF-A1 and LF-B1 binding sites in the human alpha-1-antitrypsin gene has a differential effect during development in transgenic mice.

Previous work in transfected cell lines and in nuclear extracts has led to the identification of two cis-acting elements important for transcription of the human alpha-1-antitrypsin (A1AT) gene, which bind to two liver specific trans-acting factors, LF-A1 and LF-B1. Mutations EM3 and PM1, which abolish the binding of LF-A1 and LF-B1 respectively, drastically reduce transcription activity of the A1AT gene in vitro and in cell culture. The same mutants have now been introduced in a larger DNA context and their effect has been tested in transgenic mice. A stretch of DNA was constructed which carries two transcriptional units: 18 kb of the human retinol binding protein (RBP) gene, driving the expression of the bacterial chloramphenicol acetyl transferase, linked to 17.5 kb containing the entire A1AT coding sequence with additional 5' and 3' flanking sequences. Transcription from the RBP promoter was shown to predominate in liver, and could be used as an internal marker of 'active copy number'. Mutations in the A1AT gene promoter were introduced by homologous recombination in bacterial cells. The results show that base pair substitutions in the binding site for LF-A1 and LF-B1 drastically reduce transcription in non-hepatic adult tissues, yolk sac, and fetal liver, whereas only LF-B1 binding site mutations have a marked, albeit variable, effect in adult liver.

Aging↗
PubMed1991

The use of irradiation and fusion gene transfer (IFGT) hybrids to isolate DNA clones from human chromosome region 9q33-q34.

We have generated somatic cell hybrids containing fragments of human chromosome arm 9q by an irradiation and fusion technique. No selection for human material was imposed, but of 23 clones analyzed most contained human DNA sequences and many contained multiple fragments of the human chromosome arm. A hybrid that appears to contain only two small fragments of human DNA from the regions of q33 and q34 has been used as a source from which to clone probes specific to those areas of the chromosome.

Animals↗
PubMed1991

The human homolog of the mouse brown gene maps to the short arm of chromosome 9 and extends the known region of homology with mouse chromosome 4.

The mouse brown locus encodes a tyrosinase-related protein, TRP-1. The human homolog of TRP-1 was recently cloned from a melanoma cDNA library and sequenced. We have made oligonucleotide primers corresponding to the human TRP1 3' untranslated region and used them to map the human TRP1 gene by species-specific PCR in human/rodent somatic cell hybrids. By this means, the human TRP1 gene has been mapped to the short arm of chromosome 9.

Animals↗
PubMed1991

Development of human chromosome-specific PCR primers for characterization of somatic cell hybrids.

The human chromosome complement of somatic cell hybrids must be assessed each time the hybrids are grown in culture. We have developed a panel of human-specific oligonucleotide primers for genes that have been mapped to each of the autosomes and to the X chromosome. These primers enable the human chromosome content of hybrids to be assessed rapidly by PCR. The sequence of the primers is presented together with the appropriate conditions for human DNA-specific amplification for each pair.

Animals↗
PubMed1991

Cardiac stun in infants undergoing extracorporeal membrane oxygenation.

Previous studies have shown that cardiac performance decreases in infants undergoing extracorporeal membrane oxygenation (ECMO). Some infants have an exaggerated decrease in cardiac performance during ECMO. This syndrome has been called cardiac stun. To better understand this phenomenon, we reviewed the records of infants with cardiac stun and compared them with infants who did not have the syndrome. Cardiac stun was detected in 12 of 240 infants (5.0%) undergoing ECMO. The diagnoses were congenital diaphragmatic hernia (7/12), meconium aspiration syndrome (3/12), respiratory distress syndrome (1/12), and persistent pulmonary hypertension of the newborn (1/12). The weight, gestational age, inotropic support, and time to start of ECMO were similar to infants without cardiac stun. Arterial oxygen tension was lower, carbon dioxide tension was higher, and pH was lower before ECMO in infants in whom cardiac stun developed (p less than or equal to 0.03). Cardiac arrests were more common, before ECMO, in infants in whom cardiac stun developed (6/12; p less than or equal to 0.01). Cardiac stun began at an average 2 1/2 hours after beginning ECMO (range 0.1 to 7 hours). Pulse pressure decreased from 20 mm Hg (range 10 to 45 mm Hg) before stun to 8 mm Hg (range 4 to 12 mm Hg) after stun. Heart rate did not change. Cardiac stun lasted for 33 hours (range 1 to 64 hours) on ECMO and recurred in three infants. Decreases in pump flow and increases in preload, afterload reduction, and inotropic agents did not improve cardiac performance. Survival was lower in the infants in whom cardiac stun developed (p less than or equal to 0.001). Only 5 of 12 infants (42%) survived ECMO when cardiac stun occurred. Our findings show that cardiac stun occurs infrequently during ECMO and is transient in most infants. Infants in whom cardiac stun develops appear to be more ill before ECMO and have a higher mortality after ECMO.

Aorta↗
PubMed1990

Generation of small mutation in large genomic fragments by homologous recombination: description of the technique and examples of its use.

We have developed a technique of homologous recombination in bacteria which allows the mutagenesis of large genomic fragments cloned in cosmids. The desired mutation is first introduced into a plasmid clone and is then transferred to the appropriate cosmid clone by the means of double antibiotic selection coupled with phenotypic selection. We describe three different types of construct made by this technique.

Cloning, Molecular↗
PubMed1990

Mapping of the gene TCF2 coding for the transcription factor LFB3 to human chromosome 17 by polymerase chain reaction.

A human clone corresponding to the gene for the DNA-binding factor LFB3, a protein highly homologous to the liver-specific transcription factor LFB1, has been isolated and partially sequenced. This gene is designated TCF2. Oligonucleotide primers have been designed for LFB3 and used to amplify specifically the human gene in human/rodent somatic cell hybrids using the polymerase chain reaction. By this means, the human LFB3 gene has been mapped to the long arm of chromosome 17, between the centromere and the APL breakpoint.

Animals↗
PubMed1989

The gene for human complement component C9 mapped to chromosome 5 by polymerase chain reaction.

The gene for human complement component C9 has been mapped to chromosome 5. This was achieved by using a novel application of the polymerase chain reaction to amplify specifically the human C9 gene on a background of rodent DNA in somatic cell hybrids. The assignment to chromosome 5 was confirmed by in situ hybridization to human metaphase chromosomes, giving a regional localization of 5p13.

Animals↗
PubMed1989

Cochlear nerve conduction block: an explanation for spontaneous hearing return after acoustic tumor surgery.

In the presence of an intact cochlear nerve, hearing loss has been attributed to either transection or spasm of the internal auditory artery or direct mechanical trauma to the cochlear nerve during tumor manipulation. Such events have been correlated with changes in intraoperative auditory evoked potentials. The possibility of a reversible conduction block in the cochlear nerve, however, has not been investigated. Review of four cases of delayed spontaneous recovery of hearing several months after acoustic tumor resection suggests that a conduction block phenomenon may exist. By comparing recent pertinent animal data with clinical intraoperative electrophysiologic data obtained during posterior fossa surgery in human subjects, we attempt to elucidate further the pathophysiology and intraoperative predisposing factors to cochlear nerve injury during hearing preservation procedures.

Adult↗
PubMed1989

Cochlear implantation after transmastoid labyrinthectomy.

Hearing rehabilitation with an intracochlear prosthesis is well documented in patients who have an intact otic capsule prior to implantation. However, the suitability for implantation of patients who have undergone extensive procedures involving the otic capsule such as labyrinthectomy has not been directly addressed. This report documents a case of a patient deafened by a transmastoid labyrinthectomy who subsequently received a cochlear implant. Postimplantation performance of this patient was compared with the performance of three other postlingual implant recipients. The results suggest that labyrinthectomy is not a contraindication to auditory rehabilitation by a cochlear implant. The implications of implantation in a surgically manipulated otic capsule are discussed.

Adult↗
PubMed1984

Human figure drawing ability and vestibular processing dysfunction in learning-disabled children.

Explored the relationship between vestibular function as measured by duration of postrotary nystagmus and human figure drawing ability in 40 children labeled as learning disabled. Regression analysis revealed that the variable of chronological age shared the most variance with human figure drawing scores. Postrotary nystagmus durations also shared a significant amount of variance with human figure drawing scores, while the variables of IQ and sex were nonsignificant. The results provide additional support for the assertion that some learning-disabled children evidence deficits in vestibular processing ability and that these deficits may affect performance on cognitive-perceptual tasks.

Child↗
PubMed1983

Clinical value of exercise testing in handicapped subjects.

This report describes the use of exercise testing in handicapped subjects to determine work capacity and the safety of exercise. Arm crank, bicycle, and wheelchair exercise studies are described by means of a few selected cases.

Adolescent↗
PubMed1981

Care of the bereaved.

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Community Health Nursing↗