Search PubMed⌕ Search

Biomedical subjects

S Luke

Publications and source records attributed to S Luke.

At least 19 recordsLinked to original sources
PubMed1998

Intubation complications in the critically ill child.

The acutely ill child requiring intubation is at risk for complications at three crucial points: during the intubation procedure, in the first few hours or days after intubation, and during long-term endotracheal tube (ETT) placement. Consideration must be given to the anatomic and physiologic differences between children and adults that place children at risk for acute respiratory failure and that present difficulties in providing respiratory support. Each potential complication must be understood in terms of cause, assessment, prevention, and intervention. The method of securing the ETT can decrease tube displacement, trauma to the airway, and breakdown of the skin. Intra- and interhospital transport presents more considerations in maintaining ETT placement and physiologic stability of the patient. Prevention of intubation complications in children can reduce length of stay, decrease cost of care, minimize length of time for family separation, decrease potential disabilities and prevent death in the critically ill child who requires intubation.

Adolescent↗
PubMed1998

The perfect C. elegans project: an initial report.

The soil nematode Caenorhabditis Elegans (C. elegans) is the most investigated of all multicellular organisms. Since the proposal to use it as a model organism, a series of research projects have been undertaken, investigating various aspects of this organism. As a result, the complete cell lineage, neural circuitry, and various genes and their functions have been identified. The complete C. elegans DNA sequencing and gene expression mapping for each cell at different times during embryogenesis will be identified in a few years. Given the abundance of collected data, we believe that the time is ripe to introduce synthetic models of C. elegans to further enhance our understanding of the underlying principles of its development and behavior. For this reason, we have started the Perfect C. elegans Project, which aims to produce ultimately a complete synthetic model of C. elegans' cellular structure and function. This article describes the goal, the approach, and the initial results of the project.

Animals↗
PubMed1998

Diagnosis of pulmonary tuberculosis using PCR assays on sputum collected within 24 hours of hospital admission.

There have been few studies evaluating the efficacy of polymerase chain reaction (PCR) testing in front-line clinical practice. We assessed the diagnostic yield of PCR prospectively in a blinded study of patients admitted to rule out tuberculosis and compared PCR results to a culture and clinical diagnosis of tuberculosis. Specimens were sent for routine smear, culture, and PCR analysis. Sputum sediments were submitted for PCR amplification of IS6110 sequences by an in-house assay and also the Roche Amplicor PCR assay targeting 16s ribosomal RNA genes. Eighty-five patients were enrolled: 27 patients had cultures positive for tuberculosis; 12 were smear-positive. PCR by both assays on the first specimen picked up all patients smear-positive on any specimen. A positive PCR on at least one of two specimens collected in the first 24 h was 85 and 74% sensitive and 88 and 93% specific for tuberculosis by the in-house and Roche techniques, respectively. Sensitivity in smear-negative patients was 73 and 53%, respectively. The in-house PCR detected 100% and Roche detected 95% of patients with more than paucibacillary (greater than 20 colonies) tuberculosis. We conclude that PCR may be a useful tool to evaluate patients for tuberculosis within the first hospital day.

Female↗
PubMed1998

Detection of Breast Cancer Cells in Blood Using Immunomagnetic Bead Selection and Reverse Transcription-Polymerase Chain Reaction.

Background: A sensitive and specific method for the detection of occult breast cancer cells may prove clinically useful. The purpose of this study was to investi gate cytokeratin-19 (CK-19) and gross cystic disease fluid protein (GCDFP) as potential reverse transcription-polymerase chain reaction (RT-PCR) targets for the detection of breast micrometastases. Through positive selection of breast epithelial cells by immunomagnetic bead separation, two RT-PCR assays were developed. Methods and Results: Positive selection of breast epithelial cells was performed using Ber-EP4 monoclonal antibody bound to magnetic beads. RNA was isolated and RT-PCR performed using CK-19 and GCDFP as targets. Detection sensitivity was five T47D cells spiked into 10 mL of normal blood for either target. In all, 100% (3 9/39) of normal bloods were negative for CK-19, whereas only 87% (34/39) were negative with GCDFP. In 15 patients with metastatic disease including 3 without treatment and 12 on either tamoxifen or chemotherapy, CK-19 was positive in 67% (10/15) of patients and GCDFP yielded positives in 27% (4/15) of patients tested. Conclusions: The detection of CK-19 and GCDFP in bloods from patients with metastatic breast cancer may be beneficial in determining the course of therapy, as well as having potential prognostic and diagnostic applications. Although CK-19 appears to be the more sensitive and specific marker, further investigation with both targets is warranted.

Journal Article↗
PubMed1997

Mycobacterium tuberculosis DNA Not Detected by Polymerase Chain Reaction In Air Samples From Hospital Rooms of Tuberculosis Patients.

Background: As the incidence of tuberculosis (TB) increased in the United States, the risk of occupational and nosocomial TB also increased. Airborne Mycobacterium tuberculosis (MTB) is difficult to measure directly. Quantifying MTB DNA by polymerase chain reaction in air samples obtained from isolation rooms of patients with TB would provide a measure of the number of airborne organisms produced by a patient and the efficacy of ventilation, and might predict when an individual patient is no longer infectious. Methods and Results: The air was sampled through cellulose ester filters from the isolation room of a patient with newly diagnosed pulmonary TB, from a patient on therapy for 14 days, and from adjacent offices, and an attempt was made to detect MTB DNA; however, MTB DNA was detected only on positive control filters. Conclusions: Mycobacterium tuberculosis was not detected by polymerase chain reaction in air samples from the rooms of two patients with pulmonary TB. This may have been due to the large number of room air changes with resultant rapid clearance of airborne droplet nuclei or to the limited air volume sampled. A sensitive molecular assay of airborne MTB could be used to monitor the efficacy of infection control measures by sampling a sufficient volume of isolation room air and could aid in determining when an individual patient was no longer infectious.

Journal Article↗
PubMed1996

Amplification of residual DNA sequences in sterile bronchoscopes leading to false-positive PCR results.

PCR has been used successfully for the direct detection of Mycobacterium tuberculosis in uncultured patient samples. Its potential is hindered by the risk of false-positive results as a result of either amplicon carryover of cross-contamination between patient samples. In the present study, we investigated whether residual amplifiable human or M. tuberculosis DNA could remain in sterile bronchoscopes and potentially be a cause of false-positive PCR results in subsequent patient samples. Sterilized bronchoscopes were flushed with sterile saline, and the collected eluate was submitted for PCR amplification of IS6110 sequences and exon 8 of the human p53 gene. Of a total of 55 washes of sterile bronchoscopes from two institutions, 2 (3.6%) contained amplifiable M. tuberculosis DNA and 11 (20%) contained residual human DNA. These findings indicate that residual DNA can remain in sterilized bronchoscopes and can be a source of false-positive PCR results.

Bronchoscopes↗
PubMed1995

Conservation of the Down syndrome critical region in humans and great apes.

A quarter century ago, a chimpanzee with trisomy 22 was reported to have the clinical manifestation of Down syndrome. The features of Down syndrome in human have been associated with chromosome 21 band q22.3. The recent availability of chromosome and loci specific probes has prompted us to utilize the human cosmid probe (D21S65) for the trisomy 21 region in the chromosomes of the chimpanzee (Pan troglodytes), gorilla (Gorilla gorilla) and orangutan (Pongo pygmeus). Interestingly, the hybridization site for the Down syndrome region was found on the equivalent ape chromosome 22 in all three primates (the human equivalent of chromosome 21). Apparently, these results support the notion that the Down syndrome critical region of human chromosome 21 band q22.3 is conserved in great apes, which has displayed mongolism in a chimpanzee when present in triplicate conditions. Furthermore, other probes can be used as phylogenetic signals to enhance the understanding of human descent.

Animals↗
PubMed1995

Human (Homo sapiens) and chimpanzee (Pan troglodytes) share similar ancestral centromeric alpha satellite DNA sequences but other fractions of heterochromatin differ considerably.

The euchromatic regions of chimpanzee (Pan troglodytes) genome share approximately 98% sequence similarity with the human (Homo sapiens), while the heterochromatic regions display considerable divergence. Positive heterochromatic regions revealed by the CBG-technique are confined to pericentromeric areas in humans, while in chimpanzees, these regions are pericentromeric, telomeric, and intercalary. When human chromosomes are digested with restriction endonuclease AluI and stained by Giemsa (AluI/Giemsa), positive heterochromatin is detected only in the pericentromeric regions, while in chimpanzee, telomeric, pericentromeric, and in some chromosomes both telomeric and centromeric, regions are positive. The DA/DAPI technique further revealed extensive cytochemical heterogeneity of heterochromatin in both species. Nevertheless, the fluorescence in situ hybridization technique (FISH) using a centromeric alpha satellite cocktail probe revealed that both primates share similar pericentromeric alpha satellite DNA sequences. Furthermore, cross-hybridization experiments using chromosomes of gorilla (Gorilla gorilla) and orangutan (Pongo pygmaeus) suggest that the alphoid repeats of human and great apes are highly conserved, implying that these repeat families were present in their common ancestor. Nevertheless, the orangutan's chromosome 9 did not cross-hybridize with human probe.

Animals↗
PubMed1995

The genomic sequence for Prader-Willi/Angelman syndromes' loci of human is apparently conserved in the great apes.

Chromosomal changes through pericentric inversions play an important role in the origin of species. Certain pericentric inversions are too minute to be detected cytogenetically, thus hindering the complete reconstruction of hominoid phylogeny. The advent of the fluorescence in situ hybridization (FISH) technique has facilitated the identification of many chromosomal segments, even at the single gene level. Therefore the cosmid probe for Prader-Willi (PWS)/Angelman syndrome to the loci on human chromosome 15 [q11-13] is being used as a marker to highlight the complementary sequence in higher primates. We hybridized metaphase chromosomes of chimpanzee (PTR), gorilla (GGO), and orangutan (PPY) with this probe (Oncor) to characterize the chromosomal segments because the nature of these pericentric inversions remains relatively unknown. Our observations suggest that a pericentric inversion has occurred in chimpanzee chromosome (PTR 16) which corresponds to human chromosome 15 at PTR 16 band p11-12, while in gorilla (GGO 15) and orangutan (PPY 16) the bands q11-13 complemented to human chromosome 15 band q11-13. This approach has proven to be a better avenue to characterize the pericentric inversions which have apparently occurred during human evolution. "Genetic" divergence in the speciation process which occurs through "chromosomal" rearrangement needs to be reevaluated and further explored using newer techniques.

Angelman Syndrome↗
PubMed1995

Characterization of a ring chromosome 21 by FISH-technique.

Ring chromosomes 21 that contain two copies of the Down syndrome critical region (DCR1), thereby contributing to trisomic dosage, have not been fully characterized by routine cytogenetic methods in the past. We therefore employed the fluorescence in situ hybridization (FISH) technique, using a battery of chromosome 21 probes and conclude that the ring resulted from a centromere to centromere and long arm to long arm fusion that contains alpha-satellite DNA and two copies of the D21S65 locus, but lacks beta-satellite DNA and telomeric DNA. Consequently, we suggest that the origin of the ring may be due to the misdivision of the centromere following the duplication of the long arm, forming a monocentric isochromosome followed by breakage in a region distal to the D21S65 locus and proximal to the telomeric sequences followed by reunion of the broken ends resulting in a monocentric ring. Different ring configurations or fragments were not detected, suggesting that the ring chromosome was highly stable. Apparently, the presence of two copies of Down syndrome loci within the ring chromosome, along with one copy on the normal homologue, caused the clinical consequences of Down syndrome.

Centromere↗
PubMed1994

Two Prader-Willi/Angelman syndrome loci present in an isodicentric marker chromosome.

We found an abnormal 47,XX,+mar karyotype in a patient with developmental delay, hypotonia, microcephaly, failure to thrive, and cognitive delay. When metaphases were hybridized with Prader-Willi and Angelman loci-specific probes by the FISH technique, two sites were noted at opposite positions on the marker chromosome. The alphoid satellite DNA probe documented the isodicentric nature while retention of the p arms on both sides of the marker chromosome was demonstrated by beta satellite probe. The patient does not exhibit manifestations of either syndrome despite the presence of these loci in tetrasomic dose. The present investigation suggests that other marker chromosomes be reevaluated, as their clinical manifestations are quite variable.

Abnormalities, Multiple↗
PubMed1994

Evolutionary divergence of human chromosome 9 as revealed by the position of the ABL protooncogene in higher primates.

Attempts to solve the fundamental questions regarding the descent of man are dogged by superstitions and unexamined orthodoxies. The origin of humans, established a decade ago based upon cytological analysis of ape chromosomes, continues to be called into question. Although molecular methods have provided a framework for tracing the paths of human evolution, conclusive evidence remains elusive. We have used a single ABL gene probe derived from human chromosome 9 to assess the direction of change in the equivalent ape chromosomes. This approach has resulted in a few surprises which again challenge the prevailing view of early primate evolution based solely on chromosome banding patterns. The ABL proto-oncogene is present on human chromosome 9 at band q34. Similar DNA sequences presumed to represent an ABL gene, are present on chromosome 11 in chimpanzee (Pan troglodytes) but at a different relative location, indicating that the mechanism of the origin of human chromosome 9 is far more complex than has previously been suggested. Nevertheless, in gorilla (Gorilla gorilla) and orangutan (Pongo pygmaeus), the equivalent to human chromosome band 9 q34 is apparently located on chromosome 13 at a putative telomeric position and no discernible differences could be established. Despite the presence of the ABL protooncogene on human equivalent ape chromosomes, molecular systematics will continue to generate enigmas in the evolutionary context until the entire genome is sequenced.

Animals↗
PubMed1994

Alphoid DNA diversity of a so-called monocentric Robertsonian fusion.

The centromeric heterochromatin of a Robertsonian translocation with t(13q14q), thought to be monocentric by conventional staining methods, was found to be dicentric using molecular techniques. The breakpoints were confined within the alphoid DNA subfamilies and fusion resulted in a compound centromere. The fragile nature of alphoid DNA sequences during Robertsonian translocation has opened new avenues in understanding other chromosomal aberrations involving centric fusion.

Chromosomes, Human, Pair 13↗
PubMed1994

Centromeric and telomeric repeats are stable in nonagenarians as revealed by the double hybridization fluorescent in situ technique.

We report a simple method for simultaneous identification of centromeric and telomeric repeat sequences of human chromosomes. Employing this technique, we investigated the stability of centromeres and telomeres in individuals over 90 years of age and compared them with younger controls (< 40 years). Our findings suggest that centromeric and telomeric repeats remain apparently stable in nonagenarians. These findings are enigmatic because it has been suggested that centromeres are lost in older individuals. Furthermore, telomeric shortening has been observed in aged lymphocytes and cellular senescence. However, stability of telomeric repeats noted in nonagenarians may be masked by loss followed by compensation by a process called telomeric elongation.

Adult↗