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Biomedical subjects

L A Stuart

Publications and source records attributed to L A Stuart.

10 recordsLinked to original sources
PubMed1998

Functional and pathological effects of prolonged hyperoxia in neonatal mice.

Bronchopulmonary dysplasia (BPD) commonly develops in premature infants. An improved understanding of the pathophysiology of BPD requires better models. In this study, neonatal FVB/N mice were exposed to room air or 85% oxygen for 28 days. Neonatal hyperoxia resulted in decreased alveolar septation, increased terminal air space size, and increased lung fibrosis. These changes were evident after 7 days and more pronounced by 28 days. Decreased alveolarization was preceded by decreased proliferation of lung cells. After 3 days of hyperoxia, cell proliferation was decreased compared with room air littermates. Cell proliferation continued to be decreased in the first 2 wk but normalized by 4 wk. Hyperoxia caused an increased number of inflammatory cells in lung tissue and in lung lavage fluid. Analysis of lung tissue RNA by RT-PCR showed that hyperoxia increased expression of the proinflammatory cytokines interleukin-1alpha and macrophage inflammatory protein-1alpha. Prolonged neonatal hyperoxia caused functional changes, decreasing lung volume and pulmonary compliance. We conclude that prolonged exposure of neonatal mice to hyperoxia creates a lesion that is very similar to human BPD and suggests that altered cell proliferation may be important in the pathogenesis of chronic neonatal lung disease.

Animals↗
PubMed1998

Structure of the human D1F15S1A locus: a chromosome 1 locus with 97% identity to the chromosome 3 gene coding for hepatocyte growth factor-like protein.

The human chromosome 3 locus coding for hepatocyte growth factor-like protein/macrophage stimulating protein (HGFL/MSP) is homologous to two sets of amplified loci on human chromosome 1 at 1p36. One copy of one of the amplified loci (D1F15S1A) has been further characterized by restriction enzyme and DNA sequence analysis. A total of 8331 bp of continuous sequence was determined for this locus. The first 6878 bp of sequence is 96.1% identical to the HGFL/MSP gene, while there is no homology between the two genes following nucleotide 6878. Based on the presence of a 5 bp deletion in putative exon 2 and several downstream stop codons it is very likely that this gene is a pseudogene. Screening of a human liver cDNA library with a chromosome 1-specific probe indicates that at least several other members of the chromosome 1 loci are transcribed.

Chromosomes, Human, Pair 1↗
PubMed1991

Characterization of the DNF15S2 locus on human chromosome 3: identification of a gene coding for four kringle domains with homology to hepatocyte growth factor.

A human genomic DNA library was screened by using conditions of reduced stringency with a bovine cDNA probe coding for the kringle domains in prothrombin in order to isolate the human prothrombin gene. Twelve positives were identified, three of which coded for prothrombin (Degen & Davie, 1987). Phage L5 was characterized in more detail because of its strong hybridization to the cDNA probe and its unique restriction map compared to the gene coding for human prothrombin. The gene in L5 was sequenced and found to code for a kringle-containing protein. A human liver cDNA library was screened by using a genomic probe from the gene in L5. cDNAs were isolated that contained sequence identical with regions in the gene in L5. Comparison of the cDNA with the gene indicated that the gene in L5 was composed of 18 exons separated by 17 intervening sequences and is 4690 bp in length. Exons ranged in size from 36 to 242 bp in length while intervening sequences ranged from 77 to 697 bp in length. The putative protein encoded by the gene in L5 contains four kringle domains followed by a serine protease-like domain. This domain structure is identical with that found in hepatocyte growth factor (HGF), although the two proteins are only about 50% identical. On the basis of the similarity of the protein encoded by L5 and HGF, we propose that the putative L5 protein be tentatively called HGF-like protein until a function is identified. The DNA sequence of the gene and cDNA and its translated amino acid sequence were compared against GenBank and NBRF databases. Sequences homologous to DNF15S1 and DNF15S2, human DNF15S2 lung mRNA, and rat acyl-peptide hydrolase were identified in exon 17 to the 3' end of the characterized sequence for the gene. From our results, it is apparent that the gene coding for human HGF-like protein is located at the DNF15S2 locus on human chromosome 3 (3p21). The gene for acyl-peptide hydrolase is 444 bp downstream of the gene coding for HGF-like protein, but on the complementary strand. The DNF15S2 locus has been proposed to code for one or more tumor suppressor genes since this locus is deleted in DNA from small cell lung carcinoma, other lung cancers, renal cell carcinoma, and von Hippel-Lindau syndrome.

Amino Acid Sequence↗
PubMed1991

Characterization of the mouse cDNA and gene coding for a hepatocyte growth factor-like protein: expression during development.

The cDNA and gene coding for mouse hepatocyte growth factor-like protein (HGF-like protein) were isolated and characterized. The size of the gene from the site of initiation of transcription to the polyadenylation site is 4613 bp in length and is composed of 18 exons separated by 17 intervening sequences. The exons range in size from 36 to 227 bp in length, while the intervening sequences range in size from 78 to 613 bp in length. The site of initiation of transcription was identified by primer extension analysis using total RNA isolated from mouse liver. On the basis of these results, the first exon is 146 bp in length and includes 94 bp of 5'-noncoding sequence. The sequence 5'TATGTG3' is present between 34 and 39 bp upstream of the transcription start site and could potentially be the TATA sequence found for many constitutively expressed eukaryotic genes to be the promoter for RNA polymerase II. The sequence 5'GCAAT3' at -96 to -92 may be the CCAAT sequence responsible for stimulation of transcription of some eukaryotic genes. The same sequences in the Genbank and NBRF databases were homologous to similar regions in the genes coding for both human and mouse HGF-like protein (Han et al., 1991). The acyl-peptide hydrolase gene is 410 bp downstream of the mouse HGF-like protein, but is transcribed from the complementary strand. The mouse cDNA for HGF-like protein codes for a putative protein with the same domain structure as its human homologue with four kringle domains followed by a serine protease-like domain. On the basis of the translated sequence of the cDNA, the mouse HGF-like protein would be 716 amino acids in length with a molecular weight of 80K. There are four potential N-linked carbohydrate attachment sites. The DNA and amino acid sequences of mouse HGF-like protein are compared to the human protein. Overall, the two proteins are about 80% identical with each other. In contrast to mRNA for human HGF-like protein, which is 2.4 and 3.0 kilobases in length in human liver, only the smaller species is seen in mouse and rat liver. The expression pattern of mRNA coding for HGF-like protein during development and in maternal rats was determined by Northern analysis. It is apparent that the majority of mRNA coding for HGF-like protein is expressed in liver. Messenger RNA is also expressed at a lower level in lung, adrenal, and placenta.

Amino Acid Sequence↗
PubMed1989

Brucella suis biovar 3 infection in a Kentucky swine herd.

Sows from a large farrow-to-finish operation in western Kentucky had late-term abortions. Boars and breeding-age sows were tested serologically for brucellosis, and 83 of 125 were classified as reactors. No brucellae were isolated from the tissues of 6 unbred reactor sows, but Brucella suis biovar 3 was recovered from 5 aborted fetuses. Epidemiological studies failed to determine the source of the infection.

Abortion, Veterinary↗
PubMed1985

Topical sulfacetamide vs oral erythromycin for neonatal chlamydial conjunctivitis.

Conjunctival and nasopharyngeal cultures for Chlamydia trachomatis were obtained from infants 30 days of age or younger with purulent conjunctivitis. Conjunctival specimens were also tested for other bacterial pathogens and for viruses. Most of the infants studied were black and came from a low-income, urban population. By random assignment infants received either topical treatment with 10% sulfacetamide sodium ophthalmic solution or systemic treatment with oral erythromycin estolate (50 mg/kg/day). Treatment was continued for 14 days if C trachomatis was isolated from the conjunctivae. Treatment was considered to be effective if conjunctivitis resolved and if follow-up chlamydial cultures of the conjunctivae and nasopharynx were negative at completion of therapy and two to four weeks later. Chlamydia trachomatis was isolated in the absence of other pathogens from the eyes of 37 (73%) of 51 infants with conjunctivitis. Other bacterial pathogens were isolated from four infants (8%) and viruses from none. Chlamydial infection was eradicated from 14 (93%) of 15 infants treated orally. In contrast, persistent conjunctival infection was detected in eight infants (57%) and nasopharyngeal colonization in three (21%) of 14 infants after topical treatment. It was concluded that C trachomatis is the most frequent cause of neonatal conjunctivitis in the low-income, urban population studied; that erythromycin estolate administered orally for 14 days eradicates chlamydial conjunctival and nasopharyngeal infection; and that topical sulfacetamide therapy may result in persistent conjunctival infection and nasopharyngeal colonization.

Administration, Oral↗
PubMed1981

Chlamydia trachomatis infection in mothers and infants. A prospective study.

The incidence of chlamydia trachomatis infection of the cervix during pregnancy was found to be 18% in a group of 1,327 women attending the prenatal clinic of a large urban hospital. There were no statistically significant differences between infected and uninfected women in the type or frequency of complications of pregnancy. Chlamydial infection was demonstrated in 27 (28%) of 95 infants born vaginally to infected mothers. Conjunctival infection in these infants was detected earlier than nasopharyngeal infection and the conjunctivae appeared to be the usual portal of entry for the organism. Infants were observed through the age of 12 weeks. Conjunctivae, but the chlamydial pneumonia syndrome occurred in only three (17%) of 18 infants with nasopharyngeal infection.

Chlamydia Infections↗
PubMedDate not supplied

Effect of massive small bowel resection on the Bax/Bcl-w ratio and enterocyte apoptosis.

Following small bowel resection (SBR), the remnant intestine undergoes adaptation. Enterocyte proliferation is increased and counterbalanced by increased rates of apoptosis. To elucidate a mechanism for increased enterocyte apoptosis, this study tested the hypothesis that the ratio between pro-apoptotic Bax and pro-survival Bcl-w correlates with the apoptosis that occurs following SBR. Mice (C57Bl/6; n = 76) underwent a 50% proximal SBR or sham operation. After 12 hours and 1, 2, 3, and 7 days, the ileum was removed, the apoptotic index (apoptotic bodies/crypt) was recorded, and the messenger RNA and protein for Bax and Bcl-w were quantified. The apoptotic index was equivalent in the sham and SBR mice at 12 hours; however, it was significantly elevated following SBR at every other day measured. The ratio of Bax to Bcl-w messenger RNA relative to sham operation increased after SBR at 24 hours, decreased by day 3, and returned to baseline levels by 1 week. The protein ratio showed an increase by day 1, which remained elevated through day 7. An augmented ratio of Bax to Bcl-w messenger RNA and protein corresponded with the increase in enterocyte apoptosis. Alterations in the expression ratio of these genes may play a role in establishing a new homeostatic set point between proliferation and apoptosis during adaptation.

Adaptation, Physiological↗