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Biomedical subjects

T P O'Brien

Publications and source records attributed to T P O'Brien.

At least 55 records · Page 3Linked to original sources
PubMed1995

Murine model of ocular infection by a human biovar of Chlamydia trachomatis.

PURPOSE: A human biovar of Chlamydia trachomatis was used to develop a murine model of ocular chlamydial infection. The inbred mouse model will allow detailed immunologic studies during ocular infection, and use of a human biovar for infection may aid in identification of appropriate vaccine strategies against chlamydial infections. METHODS: BALB/c, C3H/HeN, and C57B1/6J mice (n = 5 to 10 mice/group) were topically infected in the conjunctiva with C serovar of C. trachomatis. The effects were tested of single and repeated infection with 5000 inclusion-forming units (IFU) in 5 microliters and different inoculum doses. Conjunctival surfaces of both eyes were swabbed for microbiologic signs (isolation culture or direct fluorescent antibody staining) of infection over 4 to 6 weeks. Conjunctivae were removed for histopathologic study, and lymphocytes from draining cervical lymph nodes and spleens were tested for chlamydia-specific proliferative responses. Serum was obtained from all mice and tested for anti-chlamydial antibodies. RESULTS: BALB/c and C3H/HeN mice developed dose-dependent microbiologic, histopathologic, and immunologic evidence of ocular infection. Eyes of mice were culture-positive from day 7 through at least day 21, with the peak of infection at days 10 to 14 after infection. Histopathologically, the development of conjunctival subepithelial mononuclear infiltration, exudate, and loss of goblet cells occurred within 1 week. Dose-dependent lymphoproliferative responses to whole chlamydial elementary bodies were observed; anti-chlamydial antibody was detected by immunoblotting only in infected mice. CONCLUSIONS: Several strains of inbred mice are susceptible to human chlamydial biovars and may provide a useful alternative disease model in which to study the immunopathogenesis of ocular chlamydial infection and test of vaccine candidates derived from clinically relevant human biovars.

Animals↗
PubMed1994

Ophthalmology.

It is estimated that 49% to 74% of cases of contact lens-associated ulcerative keratitis could be prevented by eliminating overnight wear. Heavy alcohol consumption appears to be associated with all types of cataracts. Cigarette smokers have a nearly threefold greater risk of developing age-related macular degeneration than nonsmokers.

Eye Diseases↗
PubMed1994

Infectious crystalline keratopathy due to Streptococcus pneumoniae. Possible association with serotype.

BACKGROUND: Infectious crystalline keratopathy is a distinctive clinical entity characterized by bacterial replication within the corena without inflammation. The authors report on a patient with infectious crystalline keratopathy due to Streptococcus pneumoniae serotype 11F. They used this isolate to study the contribution of the pneumococcal polysaccharide capsule to the pathogenesis of the infectious crystalline keratopathy. METHODS: Aliquots containing 10(6) colony-forming units of pneumococci serotype 11F, serogroup 9 or 15, were inoculated into New Zealand white rabbit corneas. The corneas were examined at 24, 48, and 72 hours. Representative corneas were excised at 24 hours and processed for histopathologic analysis. RESULTS: Pauci-inflammatory crystalline lesions developed in all corneas inoculated with the serotype 11F ocular isolate by 24 hours. Suppurative keratitis developed in control corneas inoculated with serogroup 9 or 15 pneumococci. The nonocular 11F isolates produced lesions with some features compatible with infectious crystalline keratopathy. CONCLUSION: Different pneumococcal serotypes vary in their ability to produce infectious crystalline keratopathy. Because serotype differences reflect differences in the antigenic polysaccharides of the bacterial capsule, this study suggests that properties of the pneumococcal capsule may influence the initial development of infectious crystalline keratopathy.

Aged↗
PubMed1994

Fetal responses to acute fetal cocaine injection in sheep.

Maternal cocaine injection causes fetal hypoxemia, hypertension, and increased cerebral blood flow (CBF) in sheep. To test the hypothesis that increased fetal CBF is not due solely to fetal hypoxemia, we injected cocaine directly into a fetal vein. A single dose of cocaine [1 (group 1; n = 7) or 2 (group 2; n = 8) mg/kg i.v.] was administered to chronically catheterized, unanesthetized, near-term fetal sheep. Fetal CBF (microspheres), arterial blood pressure (BP), O2 content, and cerebral O2 consumption (CMRo2) were measured at baseline, 30 s, and 2, 5, and 15 min after fetal cocaine injection. Fetal CBF increased 27 +/- 9% (SE) at 5 min in group 1 and returned to baseline by 15 min, whereas fetal CBF increased 57 +/- 8% at 5 min and remained elevated at 15 min in group 2. Fetal BP increased at 30 min in both groups and remained increased at 2 min in group 1 and at 5 min in group 2. Cerebrovascular resistance increased at 30 s in both groups and then decreased at 5 min only in group 2. Fetal hypoxemia was observed in group 2 5 min after cocaine injection (arterial PO2 decreased 24 +/- 5%), whereas no hypoxemia was noted in group 1. CMRO2 was unchanged in group 1 but increased in group 2 at 5 min (41 +/- 10%) and was associated with an increase in cerebral O2 extraction. Increases in myocardial and adrenal blood flows and reductions in both small and large intestinal blood flows were noted at 5 min in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Cerebral responses to single and multiple cocaine injections in newborn sheep.

Newborn infants exposed to cocaine near birth display a wide range of neurologic abnormalities, but the mechanism or mechanisms for these injuries remain unknown. We studied the cerebral effects of a single acute dose (4 mg/kg; n = 7) and multiple binge doses (4 mg/kg hourly for 5 h; n = 7) of i.v. cocaine in unanesthetized newborn (5 +/- 1 d old) sheep. We measured cerebral blood flow, mean arterial blood pressure, arterial blood gases, and cerebral O2 metabolism. Measurements were made at baseline; 30 s; and 5, 15, and 60 min after a single injection of cocaine in the acute group and at the same time intervals after the 5th dose of cocaine in the binge group. CBF increased by 98 +/- 68% (mean +/- SD) at 30 s after a single acute dose and by 97 +/- 94% at 30 s after the 5th of five hourly binge doses. Although it returned to baseline by 5 min in the acute group, cerebral blood flow remained elevated 5, 15, and 60 min after the 5th cocaine dose in the binge group. At 30 s, mean arterial blood pressure increased by 57 +/- 21% in the acute group and 46 +/- 15% in the binge group. In both groups, mean arterial blood pressure remained elevated at 5 min. Although no change occurred in cerebral O2 metabolism in the acute group, an increase in cerebral O2 consumption (7.4 +/- 1.3 mL/100 g/min versus 5.5 +/- 1.1 at baseline) was observed at 5 min in the binge group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The prevention of localized ridge deformities using guided tissue regeneration.

Healing of extraction sockets where the buccal plate of bone has been destroyed often results in localized ridge deformities. This is most likely due to the ingrowth of extraskeletal connective tissue into the space originally occupied by the tooth which then fills with a combination of bone and soft tissue. Techniques for managing these defects have been described, but it would be preferable to prevent them from occurring at all. Using the principles of guided tissue regeneration, a surgical technique is described that can be applied to post-extraction sites that are deficient in alveolar bone thereby preventing localized ridge deformities. Representative cases are presented illustrating the technique.

Alveolar Bone Loss↗
PubMed1993

Ophthalmology.

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Humans↗
PubMed1993

Fetal responses to acute maternal cocaine injection in sheep.

Maternal cocaine abuse has been associated with neonatal neurological and neurobehavioral problems of unknown pathogenesis. We administered a single intravenous dose of cocaine (2 mg/kg) to 12 unanesthetized pregnant sheep; their fetuses had been catheterized in utero 2 days before the study. We measured fetal cerebral blood flow (CBF), cerebral metabolic rate of O2 (CMRO2), mean arterial blood pressure (MAP), and blood gases before and 2, 5, 15, and 30 min after maternal cocaine injection. Fetal CBF increased by 37 +/- 33% (mean +/- SD) at 5 min and returned to baseline by 15 min. Regional brain blood flow changes paralleled CBF changes with the greatest increases occurring in cerebellum (54 +/- 43%) and brain stem (54 +/- 52%). Cerebral vascular resistance was decreased for cerebellum (22%) and brain stem (19%) but was unchanged for cerebral hemispheres and caudate. Increased CBF at 5 min was associated with a 20 +/- 9% increase in fetal MAP and a 38 +/- 13% decrease in fetal arterial O2 content. Fetal CMRO2 was unchanged. There was a decrease in fetal intestinal blood flow at 2 min, an increase in myocardial, adrenal, and renal blood flow at 5 min, and no change in placental blood flow. Maternal cocaine injection causes fetal hypoxemia, hypertension, and increased CBF. Possible mechanisms for cerebral vasodilation (in some areas) include hypoxemia, impaired autoregulatory response to increased blood pressure, and/or direct or indirect vascular effects of cocaine or its metabolites.

Animals↗
PubMed1992

Ophthalmology.

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Acquired Immunodeficiency Syndrome↗
PubMed1992

Expression of the growth factor-inducible immediate early gene cyr61 correlates with chondrogenesis during mouse embryonic development.

cyr61 is a growth factor-inducible immediate early gene initially identified in serum-stimulated mouse fibroblasts. It encodes a member of an emerging family of cysteine-rich secreted proteins that includes a connective tissue growth factor. We show here that cyr61 is expressed in the developing mouse embryo and extraembryonic tissues. In the placenta, cyr61 is expressed in regions of trophoblastic origin, including the ectoplacental cone and the trophoblastic giant cells. In the midgestation embryo, cyr61 is expressed in the smooth muscle vessel walls of the arterial circulatory system. Most notably, expression is found in developing cartilaginous elements, including the limbs, ribs, and prevertebrae. In addition, regions of the chondrocranium and craniofacial elements, such as Meckel's cartilage, also express cyr61. Thus, cyr61 transcript is found in mesenchymal cells of both mesodermal and ectodermal origin during their differentiation into chondrocytes. The temporal and spatial regulation of cyr61 expression and the biochemical features of its encoded protein suggest that cyr61 may be important for the normal growth, differentiation, or morphogenesis of the cartilaginous skeleton of the embryo.

Amino Acid Sequence↗
PubMed1991

Promoter function and structure of the growth factor-inducible immediate early gene cyr61.

cyr61 is an immediate early gene that is transcriptionally activated in 3T3 fibroblasts by serum, platelet-derived growth factor, fibroblast growth factor, and the tumor promoter TPA with kinetics similar to the induction of c-fos. cyr61 encodes a secreted protein that is associated with the cell surface and the extracellular matrix, and may play a role in cell-cell communication. We report here the complete nucleotide sequence of the mouse cyr61 gene, which contains four short introns. The transcription start site was mapped by S1 nuclease and primer extension analyses. A 2 kb 5' flanking DNA fragment functions as a serum-inducible promoter. This DNA fragment contains a poly(CA) sequence that can adopt the Z DNA form. In addition, it contains a sequence that resembles the serum response element (SRE) originally identified in the c-fos promoter. We show that deletion of the cry61 SRE-like sequence abrogates serum inducibility. Furthermore, this SRE-like sequence is sufficient to confer serum and growth factor inducibility when linked to a basal promoter, and binds the 67 kD serum response factor in vitro. We conclude that the cyr61 SRE functions as a serum response element and may account for the coordinate activation of cyr61 and c-fos.

Amino Acid Sequence↗
PubMed1990

Implantation of scleral-fixated posterior chamber intraocular lenses.

A surgical technique for implanting a posterior chamber intraocular lens (IOL) in eyes without capsular or zonular support is presented. A 10-0 polypropylene suture attached to a standard needle is tied to the apex of each haptic and passed transclerally through the ciliary sulcus to secure the haptics at the 3 o'clock and 9 o'clock meridians. This technique produced good visual results in six aphakic patients who were contact lens intolerant, two patients in whom capsular or zonular rupture at the time of cataract surgery precluded standard nonsuture fixation techniques, one patient who had intracapsular cataract extraction for a subluxated, cataractous lens, and one patient who had secondary IOL implantation in combination with penetrating keratoplasty for aphakic bullous keratopathy. Advantages over other techniques of posterior chamber lens implantation in the absence of capsular support include technical ease, avoidance of iris fixation, and more precise placement of scleral fixation sutures, thus minimizing IOL decentration.

Adult↗
PubMed1990

Pip92: a short-lived, growth factor-inducible protein in BALB/c 3T3 and PC12 cells.

pip92 is a cellular immediate-early gene inducible by serum growth factors in fibroblasts. It is also induced in the rat pheochromocytoma cell line PC12 by agents that cause proliferation, neuronal differentiation, and membrane depolarization. We show that the pip92-encoded polypeptide is a proline-rich protein of 221 amino acids, has an extremely short half-life, and is localized in the cytoplasm. We hypothesize that Pip92 plays a role in mediating the cellular responses to a variety of extracellular signals.

Adrenal Gland Neoplasms↗
PubMed1990

Expression of cyr61, a growth factor-inducible immediate-early gene.

A set of immediate-early genes that are rapidly activated by serum or purified platelet-derived growth factor in mouse 3T3 fibroblasts has been previously identified. Among these genes, several are related to known or putative transcription factors and growth factors, supporting the notion that some of these genes encode regulatory molecules important to cell growth. We show here that a member of this set of genes, cyr61 (originally identified by its cDNA 3CH61), encodes a 379-amino-acid polypeptide rich in cysteine residues. cyr61 can be induced through protein kinase C-dependent and -independent pathways. Unlike many immediate-early genes that are transiently expressed, the cyr61 mRNA is accumulated from the G0/G1 transition through mid-G1. This expression pattern is due to persistent transcription, while the mRNA is rapidly turned over during the G0/G1 transition and in mid-G1 at the same rate. In logarithmically growing cells, the cyr61 mRNA level is constant throughout the cell cycle. Cyr61 contains an N-terminal secretory signal sequence; however, it is not detected in the culture medium by immunoprecipitation. Cyr61 is synthesized maximally at 1 to 2 h after serum stimulation and has a short half-life within the cell.

Amino Acid Sequence↗
PubMed1989

Fucosidosis: ultrastructural study of the eye in an adult.

The ocular histopathological and ultrastructural features of fucosidosis in a man who survived to the age of 25 years are reported. Virtually all of the cells of the eye contained cytoplasmic, membrane-bound, and confluent areas of fibrillogranular and multilaminated material. The most striking accumulations were present within the endothelial cells lining blood vessels and corneal endothelium, and the least amount was present in the uveal melanocytes.

Adult↗