PubMed Health⌕ Search

Biomedical subjects

R S Jackson

Publications and source records attributed to R S Jackson.

At least 19 recordsLinked to original sources
PubMed2001

The eicosanoid, 15-(S)-HETE, stimulates secretion of mucin-like glycoprotein by the corneal epithelium.

PURPOSE: The eicosanoid, 15-(S)-hydroxyeicosa-5Z, 8Z-11Z, 13E-tetraenoic acid (15-(S)-HETE), is known to stimulate production of mucin glycoprotein by airway epithelium. This study investigated the effect of 15-(S)-HETE on the mucin glycoprotein secretion by the corneal epithelium. METHODS: To determine the effect of dose, corneas of anesthetized New Zealand White rabbits were treated with 50, 500, or 5,000 nM 15-(S)-HETE in artificial tears for 120 minutes. To determine the time to onset of the response, corneas were treated with 500 or 1,000 nM 15-(S)-HETE in balanced salt solution for periods ranging from 5 to 120 minutes. Corneas were fixed for electron microscopy in fixative containing 0.5% cetylpyridinium chloride (CPC) to stabilize the layer of mucin-like glycoprotein on the corneal surface. The mucin layer thickness was measured by image analysis of electron micrographs. RESULTS: The layer of CPC-fixed mucin-like glycoprotein on the surface of control corneas was 0.46 +/- 0.04 microm thick. After treatment with 15-(S)-HETE, the thickness of the mucin layer increased to 0.64 +/- 0.1 microm at 50 or 5,000 nM HETE and as much as 1.02 +/- 0.2 microm in response to 500 nM HETE. Mucin thickness reached a statistical maximum of 0.59 +/- 0.1 microm after only 5 minutes of exposure to 500 or 1,000 nM HETE. CONCLUSIONS: Exposure of the cornea to 15-(S)-HETE causes a rapid-onset increase in the thickness of a layer of mucin-like glycoprotein on the surface of the corneal epithelium. This supports previous reports that corneal epithelial cells produce mucin and suggests that treatment with topical 15-(S)-HETE may be effective in treating ocular surface mucin deficiency in dry eye syndrome.

Animals↗
PubMed2000

Vertebral artery anomaly with atraumatic dissection causing thromboembolic ischemia: a case report.

STUDY DESIGN: A case report is presented. OBJECTIVES: To illustrate a rare cause of atraumatic vertebral artery dissection resulting from anomalous entry of the vessel at the C3 transverse foramen induced by normal physiologic head and neck motion, and to review vertebral artery anatomy and mechanisms whereby it is vulnerable to pathologic compression. SUMMARY OF BACKGROUND DATA: The vertebral artery usually enters the transverse foramen at C6. Rarely, the artery enters at C5 or C4. Only one prior case with entry at C3 has been reported. That patient experienced recurrent quadriplegia and locked-in syndrome caused by vertebral artery obstruction. A 27-year-old woman with a history of classic migraine experienced neurologic symptoms on three occasions related to physiologic neck and arm movements. Magnetic resonance angiogram was not diagnostic, but standard arteriography demonstrated anomalous vertebral artery entry into the C3 transverse foramen and focal dissection. METHODS: Pertinent literature and the patient's history, physical examination, and radiologic studies were reviewed. RESULTS: Standard cervico-cerebral arteriogram demonstrated focal dissection at C4 and thromboembolic complications in distal vertebral and basilar arteries. Initially, diagnosis by magnetic resonance angiogram was elusive. However, arteriography allowed prompt diagnosis followed by anticoagulation with resolution of neurologic symptoms. CONCLUSIONS: Vertebral artery dissection without trauma is rare, but should be considered when neurologic symptoms accompany physiologic cervical movements. For cases in which vertebrobasilar thromboembolic ischemia is suspected, magnetic resonance angiogram may prove inadequate for demonstrating the causative vascular pathology. Therefore, standard cervico-cerebral arteriography should be performed.

Adult↗
PubMed2000

The role of melanocortin signalling in the control of body weight: evidence from human and murine genetic models.

The peptide products of the pro-opiomelanocortin (POMC) gene have established roles in the control of physiological processes as diverse as adrenal steroidogenesis, skin pigmentation, analgesia and inflammation. In the last 5 years, evidence accumulated from murine and human genetic models of disrupted melanocortin signalling has firmly established a central role for a population of hypothalamic neurons expressing POMC in the control of appetite and body weight. Of the five known melanocortin receptors, the MC4R has been most closely linked to body weight regulation. While a-MSH is active at this receptor and suppresses appetite after central injection, important roles for other POMC-derived products have not been excluded. The development of pharmacological agonists acting on, or mimicking, the hypothalamic melanocortinergic pathway may provide exciting opportunities for the therapy of human obesity.

Animals↗
PubMed2000

Analysis of posterior spinal wiring in a validated rabbit model.

Mamillary and spinous process base wiring did not improve L5-L6 posterolateral fusion rate, stiffness, or strength in a previously established rabbit model. Specimen radiography significantly underestimated fusion rate when compared with manual palpation (37% versus 68%). Fused specimens were significantly stiffer (67.2 N/mm versus 41.1 N/mm) and stronger (177 N versus 121 N) in tension than were nonfused specimens. Deep wound infection, detected only at the time of sacrifice, apparently was more common with internal fixation (43% versus 21%). Noninfected specimens were significantly stiffer (63.3 N/mm versus 43.0 N/mm) and stronger (176 N versus 107 N) than were infected specimens.

Animals↗
PubMed1999

Intermediate filament, laminin and integrin expression in lacrimal gland acinar cells: comparison of an immortalized cell line to primary cells, and their response to retinoic acid.

PURPOSE: The goal of this study was to characterize intermediate filament, integrin and laminin expression by rabbit lacrimal gland acinar cells in culture, to determine whether retinoic acid (RA) alters expression of these proteins and to compare primary cells to an immortalized rabbit lacrimal gland acinar cell line using flow cytometric analysis. METHODS: Primary cells, maintained in serum free medium, were exposed to 10(-6) M retinoic acid for 24 hours. Immortalized cells were grown in defined medium with Nu-Serum and exposed to retinoic acid. Cells were labeled with monoclonal antibodies to cytokeratins (AE1, AE2, AE3, AE5, CK10/13, CK18), integrins (alpha(3), alpha(6), alpha(V), beta(1), beta(2), beta(3) and beta(4)), laminin, or vimentin and with FITC-conjugated secondary antibodies. Cells were analyzed for antigen expression by flow cytometry and immunocytochemistry. RESULTS: Primary and immortalized cells expressed type I and type II epithelial cytokeratins (AE1 and AE3), cytokeratin 18, and cytokeratin 3 (AE5) Both cell types were negative to AE2 and CK10/13. Primary and immortalized cells expressed vimentin in culture, with immortalized cells expressing this protein at higher levels. Lacrimal acinar cells appear to synthesize laminin which was detected intracellularly in both cells types. Integrins alpha(6) (CD49f) and alpha(V) (CD51) were expressed by primary and immortalized cells. Expression of integrin alpha(6) was 10-fold higher in immortalized cells compared to primary cells. Retinoic acid increased integrin alpha( V) expression by primary and immortalized cells 1.3-fold and 3-fold, respectively, and caused a slight increase in integrin alpha(6) expression by primary cells. Both cell types also expressed integrins beta( 1), beta(2) and beta(3), but beta(4) was detected only in immortalized cells. Lacrimal acinar cells do not express integrin alpha(3). CONCLUSIONS: Expression of cytokeratins, laminin and integrins by primary and immortalized cells was similar, suggesting that the immortalized cell line is a good model for the study of lacrimal structure and function. Since retinoic acid up-regulated only integrin alpha(V), but not cytokeratins, these cells appear to be highly differentiated. Flow cytometry is a useful method for analysis of protein expression by lacrimal acinar cells.

Animals↗
PubMed1999

The African American church and university partnerships: establishing lasting collaborations.

This article highlights the experiences of the Health Wise Church Project, a community outreach initiative between a diverse group of African American churches and a university health education program. The objective of the program was to develop early detection and illness prevention networks among older church members. Not all partnerships results in long-term collaborations, and this article makes a clear distinction between different types of "working together" arrangements. The project discussed in this article presents a four-stage model to illustrate how organizations achieve collaborative partnerships. Involving community partners in the early phase of project planning contributed to the success of the church-university collaboration. This type of shared planning helped to sustain community interest during the project's implementation.

Black or African American↗
PubMed1998

Molecular and cellular regulation of prohormone processing.

The processing of prohormones involves cleavage at specific basic amino acids by members of the subtilisin-like serine endoprotease family, followed by trimming of the COOH terminus by carboxypeptidase E. The enzymes are regulated by the intra-organelle ionic environment, through post-translational processing and by interaction with endogenous inhibitors. Much has been learned about their catalytic function and cell biology from in vitro gene transfer experiments using chimeric molecules and by site-directed mutagenesis. Further insight into their molecular properties and physiological function has been gained recently from the study of in vivo mutants.

Amino Acid Sequence↗
PubMed1997

Obesity and impaired prohormone processing associated with mutations in the human prohormone convertase 1 gene.

Human obesity has an inherited component, but in contrast to rodent obesity, precise genetic defects have yet to be defined. A mutation of carboxypeptidase E (CPE), an enzyme active in the processing and sorting of prohormones, causes obesity in the fat/fat mouse. We have previously described a women with extreme childhood obesity (Fig. 1), abnormal glucose homeostasis, hypogonadotrophic hypogonadism, hypocortisolism and elevated plasma proinsulin and pro-opiomelanocortin (POMC) concentrations but a very low insulin level, suggestive of a defective prohormone processing by the endopeptidase, prohormone convertase 1 (PC1; ref. 4). We now report this proband to be a compound heterozygote for mutations in PC1. Gly-->Arg483 prevents processing of proPC1 and leads to its retention in the endoplasmic reticulum (ER). A-->C+4 of the intro-5 donor splice site causes skipping of exon 5 leading to loss of 26 residues, a frameshift and creation of a premature stop codon within the catalytic domain. PC1 acts proximally to CPE in the pathway of post-translational processing of prohormones and neuropeptides. In view of the similarity between the proband and the fat/fat mouse phenotype, we infer that molecular defects in prohormone conversion may represent a generic mechanism for obesity, common to humans and rodents.

Amino Acid Sequence↗
PubMed1996

Simplified technique to measure mandibular range of motion.

The validity and reliability of a simplified technique to measure mandibular range of motion was studied in 10 dentate subjects without symptoms. The simplified technique consisted of marking with a pencil the centric relation and maximum right, left, and protrusive positions and maximum opening. These markings were made on a tongue blade held against the maxillary anterior teeth with the mesioincisal embrasures between the mandibular central incisors used as a reference. Range of motion was also measured with a mandibular kinesiograph as the control. Each method was repeated five times on each subject by each of three investigators. Intraclass correlation coefficient demonstrated a moderate level of agreement between the two techniques and high inter-rater reliability for the three investigators for all positions except maximum left movement. These data support the hypothesis that this simplified technique is a valid and reliable way to measure mandibular range of motion.

Adult↗
PubMed1994

Implementing continuous quality improvement in primary care: implications for preventive services.

The implementation of CQI must be done in a manner that capitalizes on the challenges of primary care, including the professional autonomy of the physician, the availability of data, issues of cost and efficiency of service, and the expanding role of patient expectations in quality care. Analysis of these factors is based on an ongoing study designed to help community-based primary care practices increase the utilization of prevention and early detection services offered to patients.

Cost-Benefit Analysis↗
PubMed1994

Comparison of paired short Synacthen and insulin tolerance tests soon after pituitary surgery.

The cortisol responses to hypoglycaemia (insulin tolerance test, ITT) and tetracosactrin (short Synacthen test, SST) were compared after hypophysectomy to evaluate the SST for the assessment of hypothalamo-pituitary-adrenocortical (HPA) axis function in the immediate post-operative period. In 12 patients who were tested a mean of 21 months postoperatively (range 1-96) peak plasma cortisol in the SST correlated with that in the ITT (r = 0.90). Correlation was also seen in 12 patients tested a mean of 9 days (range 4-18) after hypophysectomy (r = 0.73). Basal-peak cortisol increments did not correlate. The peak plasma cortisol response in each test was classified by comparison with a reference value of 550 nmol/L. On this basis there was a notable discrepancy between the ITT and SST results in only one patient who was tested 4 days after hypophysectomy. The close correlation between ITT and SST responses after pituitary surgery extends into the immediate post operative period and indicates that the latter test can be used to screen HPA axis function at this time.

Adolescent↗
PubMed1992

Capgras syndrome in adolescence.

Capgras syndrome, the delusion of substitution, has rarely been reported in adolescents. The etiology is unknown, and intense controversy surrounds the debate over the relative importance of biological versus psychological factors. Presented here are two cases of Capgras syndrome in adolescents and a review of the relevant biological, neuropsychological, and psychodynamic literature. The authors suggest that the psychological processes underlying the Capgras delusion are mediated by neuroanatomical connections between various brain areas and hypothesize that the fundamental lesion in Capgras syndrome may be the patient's inability or failure to acknowledge the authenticity of a person they clearly recognize.

Adolescent↗
PubMed1991

Are patients with low serum thyroid stimulating hormone and normal total thyroxine hyperthyroid? Usefulness of 99mTc pertechnetate uptake.

The records of 107 patients who had had thyroid 99m Tc pertechnetate uptake measured, were reviewed. In patients with normal serum thyroxine (T4) and thyroid stimulating hormone (TSH), 35 of 36 with normal uptake and three with high uptake were clinically euthyroid. In patients with high serum T4 and low TSH, seven had normal and 29 had high uptake and all were clinically hyperthyroid. In patients with normal serum T4 and low TSH, 10 of 11 with high uptake were clinically hyperthyroid whereas only two of 18 with normal uptake were. The sensitivity, specificity and positive predictive value of pertechnetate uptake measurements were 83%, 94%, and 91%, respectively. The measurement of pertechnetate uptake is a rapid investigation and may help in the interpretation of patients with undetectable serum TSH found in the presence of normal serum T4.

Adult↗