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Biomedical subjects

C Olson

Publications and source records attributed to C Olson.

At least 19 recordsLinked to original sources
PubMed2006

Association of connexin36 and zonula occludens-1 with zonula occludens-2 and the transcription factor zonula occludens-1-associated nucleic acid-binding protein at neuronal gap junctions in rodent retina.

Most gap junctions between neurons in mammalian retina contain abundant connexin36, often in association with the scaffolding protein zonula occludens-1. We now investigate co-association of connexin36, zonula occludens-1, zonula occludens-2 and Y-box transcription factor 3 (zonula occludens-1-associated nucleic acid-binding protein) in mouse and rat retina. By immunoblotting, zonula occludens-1-associated nucleic acid-binding protein and zonula occludens-2 were both detected in retina, and zonula occludens-2 in retina was found to co-immunoprecipitate with connexin36. By immunofluorescence, the four proteins appeared as puncta distributed in the plexiform layers. In the inner plexiform layer, most connexin36-puncta were co-localized with zonula occludens-1, and many were co-localized with zonula occludens-1-associated nucleic acid-binding protein. Moreover, zonula occludens-1-associated nucleic acid-binding protein was often co-localized with zonula occludens-1. Nearly all zonula occludens-2-puncta were positive for connexin36, zonula occludens-1 and zonula occludens-1-associated nucleic acid-binding protein. In the outer plexiform layer, connexin36 was also often co-localized with zonula occludens-1-associated nucleic acid-binding protein. In connexin36 knockout mice, labeling of zonula occludens-1 was slightly reduced in the inner plexiform layer, zonula occludens-1-associated nucleic acid-binding protein was decreased in the outer plexiform layer, and both zonula occludens-1-associated nucleic acid-binding protein and zonula occludens-2 were markedly decreased in the inner sublamina of the inner plexiform layer, whereas zonula occludens-1, zonula occludens-2 and zonula occludens-1-associated nucleic acid-binding protein puncta persisted and remained co-localized in the outer sublamina of the inner plexiform layer. By freeze-fracture replica immunogold labeling, connexin36 was found to be co-localized with zonula occludens-2 within individual neuronal gap junctions. In addition, zonula occludens-1-associated nucleic acid-binding protein was abundant in a portion of ultrastructurally-defined gap junctions throughout the inner plexiform layer, and some of these junctions contained both connexin36 and zonula occludens-1-associated nucleic acid-binding protein. These distinct patterns of connexin36 association with zonula occludens-1, zonula occludens-2 and zonula occludens-1-associated nucleic acid-binding protein in different sublaminae of retina, and differential responses of these proteins to connexin36 gene deletion suggest differential regulatory and scaffolding roles of these gap junction accessory proteins. Further, the persistence of a subpopulation of zonula occludens-1/zonula occludens-2/zonula occludens-1-associated nucleic acid-binding protein co-localized puncta in the outer part of the inner plexiform layer of connexin36 knockout mice suggests close association of these proteins with other structures in retina, possibly including gap junctions composed of an as-yet-unidentified connexin.

Animals↗
PubMed2005

Detecting nonlinearity in structural systems using the transfer entropy.

The transfer entropy was recently proposed as a means of exploring coupling in dynamical systems. Transfer entropy is an information theoretic that quantifies the degree to which one dynamical process affects the transition probabilities (dynamics) of another. Here we demonstrate how this metric may be utilized to detect the presence of nonlinearity in a system. Using the method of surrogate data, the transfer entropy computed at various lag times are compared to values computed from linearized surrogates. The transfer entropy is shown to be a more sensitive indicator of nonlinearity than is the mutual information for both simulated and experimental data. This technique is particularly applicable to the field of structural health monitoring, where damage is often equated with the presence of a nonlinearity in an otherwise linear system.

Journal Article↗
PubMed2004

High-resolution proteomic mapping in the vertebrate central nervous system: close proximity of connexin35 to NMDA glutamate receptor clusters and co-localization of connexin36 with immunoreactivity for zonula occludens protein-1 (ZO-1).

Combined confocal microscopy and freeze-fracture replica immunogold labeling (FRIL) were used to examine the connexin identity at electrical synapses in goldfish brain and rat retina, and to test for "co-localization" vs. "close proximity" of connexins to other functionally interacting proteins in synapses of goldfish and mouse brain and rat retina. In goldfish brain, confocal microscopy revealed immunofluorescence for connexin35 (Cx35) and NMDA-R1 (NR1) glutamate receptor protein in Mauthner Cell/Club Ending synapses. By FRIL double labeling, NR1 glutamate receptors were found in clusters of intramembrane particles in the postsynaptic membrane extraplasmic leaflets, and these distinctive postsynaptic densities were in close proximity (0.1-0.3 microm) to neuronal gap junctions labeled for Cx35, which is the fish ortholog of connexin36 (Cx36) found at neuronal gap junctions in mammals. Immunogold labeling for Cx36 in adult rat retina revealed abundant gap junctions, including several previously unrecognized morphological types. As in goldfish hindbrain, immunogold double labeling revealed NR1-containing postsynaptic densities localized near Cx36-labeled gap junction in rat inferior olive. Confocal immunofluorescence microscopy revealed widespread co-localization of Cx36 and ZO-1, particularly in the reticular thalamic nucleus and amygdala of mouse brain. By FRIL, ZO-1 immunoreactivity was co-localized with Cx36 at individual gap junction plaques in rat retinal neurons. As cytoplasmic accessory proteins, ZO-1 and possibly related members of the membrane-associated guanylate kinase (MAGUK) family represent scaffolding proteins that may bind to and regulate the activity of many neuronal gap junctions. These data document the power of combining immunofluorescence confocal microscopy with FRIL ultrastructural imaging and immunogold labeling to determine the relative proximities of proteins that are involved in short- vs. intermediate-range molecular interactions in the complex membrane appositions at synapses between neurons.

Animals↗
PubMed2002

Connexin29 expression, immunocytochemistry and freeze-fracture replica immunogold labelling (FRIL) in sciatic nerve.

The recently discovered connexin29 (Cx29) was reported to be present in the central and peripheral nervous systems (CNS and PNS), and its mRNA was found in particular abundance in peripheral nerve. The expression and localization of Cx29 protein in sciatic nerve were investigated using an antibody against Cx29. The antibody recognized Cx29 in HeLa cells transfected with Cx29 cDNA, while nontransfected HeLa cells were devoid of Cx29. Immunoblotting of sciatic nerve homogenate revealed monomeric and possibly higher molecular weight forms of Cx29. These were distinguished from connexin32 (Cx32), which also is expressed in peripheral nerve. Double immunofluorescence labelling for Cx29 and Cx32 revealed only partial colocalization of the two connexins, with codistribution at intermittent, conical-shaped striations along nerve fibers. By freeze-fracture replica immunogold labelling (FRIL), Cx32 was found in gap junctions in the outermost layers of myelin, whereas Cx29-immunogold labelling was found only in the innermost layer of myelin in close association with hexagonally arranged intramembrane particle (IMP) 'rosettes' and gap junction-like clusters of IMPs. Although both Cx32 and Cx29 were detected in myelin of normal mice, only Cx29 was present in Schwann cell membranes in Cx32 knockout mice. The results confirm that Cx29 is a second connexin expressed in Schwann cells of sciatic nerve. In addition, Cx29 is present in distinctive IMP arrays in the inner most layer of myelin, adjacent to internodal axonal plasma membranes, where this connexin may have previously unrecognized functions.

Animals↗
PubMed2001

Measures of food insecurity/security.

ABSTRACT Nutrition education has the potential to play an important role in ensuring food security and improving nutritional status. Therefore, food security is recommended for inclusion in nutrition education evaluation efforts. Considerable progress has been made in developing brief tools that can be used to measure food security at the household level. These tools are reliable in population-based surveys, and some studies have found that measures of food security are associated with nutrient intake. Hence, these tools can be valuable in monitoring, in community needs assessment, and in planning. These tools may also have the potential for use in evaluating nutrition education activities; this potential will be enhanced by research into the capacity of these tools to identify changes within households over time as a result of nutrition education and their sensitivity and reliability in doing so.

Diet↗
PubMed2000

Lack of association between Kawasaki syndrome and Chlamydia pneumoniae infection: an investigation of a Kawasaki syndrome cluster in San Diego County.

BACKGROUND: The etiology of Kawasaki syndrome (KS), the leading cause of acquired coronary artery disease in children, is unknown. Recent studies have suggested that Chlamydia pneumoniae, a common respiratory pathogen associated with an increased risk of heart disease, might lead to KS. OBJECTIVE: To assess whether KS was associated with an elevated risk of having a current or antecedent infection with C. pneumoniae. METHODS: Blood, urine and pharyngeal specimens from KS patients in San Diego County, CA, during a period of high KS incidence were analyzed for evidence of recent C. pneumoniae infection by culture, PCR and serology. Specimens collected from two control groups, family members of KS patients and age-matched children attending outpatient clinics for well child visits, were similarly analyzed. RESULTS: Thirteen cases were identified. Forty-five outpatient controls and an average of three family members per patient were enrolled in the study. All specimens tested negative for the presence of C. pneumoniae by PCR and culture except for one blood specimen from the mother of a case-patient. Serologic analysis of patients and a subset of outpatient and family controls revealed no evidence of current C. pneumoniae infection; 4 of 13 adult family controls had IgG titers consistent with past exposure to C. pneumoniae. Case patients were no more likely than outpatient controls to have had a respiratory illness in the preceding 2 months (11 of 13 patients vs. 35 of 45 controls; odds ratio, 1.57; 95% confidence interval, 0.3 to 11.9). CONCLUSIONS: We found no evidence that C. pneumoniae infection was associated with KS.

Adolescent↗
PubMed2000

Safety of oral versus intravenous hydration during induction therapy with intravenous foscarnet in AIDS patients with cytomegalovirus infections.

We undertook a study to compare the safety of intravenous (i.v.) versus oral hydration to prevent nephrotoxicity associated with the use of foscarnet for induction therapy of cytomegalovirus (CMV) infection in HIV-infected persons. Patients, given foscarnet at a dose of 90 mg/kg every 12 h, were randomized to receive either i.v. or oral hydration. Thirty-seven patients were given i.v. hydration and 44 were given oral hydration. Median duration of therapy for both groups was 17 days. There was no difference between the 2 groups in either serious adverse events or rise of creatinine to > or = 2.0 mg/dl. However, serum creatinine, while generally remained within normal limits, increased more in patients who received oral hydration after 10 days of therapy (significant only by slope analysis, P < 0.05). Although i.v. hydration provided better protection against nephrotoxicity, oral hydration was relatively safe and convenient provided that creatinine clearance (CrCl) is monitored closely.

AIDS-Related Opportunistic Infections↗
PubMed1999

Effects of pharmacological doses of nandrolone decanoate and progressive resistance training in immunodeficient patients infected with human immunodeficiency virus.

This nonplacebo-controlled, open label, randomized study was conducted to test the hypotheses that pharmacological doses of nandrolone decanoate would increase lean body tissue, muscle mass, and strength in immunodeficient human immunodeficiency virus-infected men, and that these effects would be enhanced with progressive resistance training (PRT). Thirty human immunodeficiency virus-positive men with fewer than 400 CD4 lymphocytes/mm3 were randomly assigned to receive weekly injections of nandrolone alone or in combination with supervised PRT at 80% of the one-repetition maximum three times weekly for 12 weeks. Total body weight increased significantly in both groups (3.2 +/- 2.7 and 4.0 +/- 2.0 kg, respectively; P < 0.001), with increases due primarily to augmentation of lean tissue. Lean body mass determined by dual energy x-ray absorptiometry increased significantly more in the PRT group (3.9 +/- 2.3 vs. 5.2 +/- 5.7 kg, respectively; P = 0.03). Body cell mass by bioelectrical impedance analysis increased significantly (P < 0.001) in both groups (2.6 +/- 1.0 vs. 2.9 +/- 0.8 kg), but to a similar magnitude (P = NS). Significant increases in cross-sectional area by magnetic resonance imaging of total thigh muscles (1538 +/- 767 and 1480 +/- 532 mm2), quadriceps (705 +/- 365 and 717 +/- 288 mm2), and hamstrings (842 +/- 409 and 771 +/- 295 mm2) occurred with both treatment strategies (P < 0.001 for the three muscle areas); these increases were similar in both groups (P = NS). By the one-repetition method, strength increased in both upper and lower body exercises, with gains ranging from 10.3-31% in the nandrolone group and from 14.4-53.0% in the PRT group (P < 0.006 with one exception). Gains in strength were of significantly greater magnitude in the PRT group (P < or = 0.005 for all comparisons), even after correction for lean body mass. Thus, pharmacological doses of nandrolone decanoate yielded significant gains in total weight, lean body mass, body cell mass, muscle size, and strength. The increases in lean body mass and muscular strength were significantly augmented with PRT.

Adult↗
PubMed1999

Anterior instability of the glenohumeral joint with humeral avulsion of the glenohumeral ligament. A review of 41 cases.

We studied retrospectively a consecutive series of 547 shoulders in 529 patients undergoing operation for instability. In 41, the cause of instability was considered to be lateral avulsion of the capsule, including the inferior glenohumeral ligament, from the neck of the humerus, the HAGL lesion. In 35, the lesion was found at first exploration, whereas in six it was noted at revision of a previous failed procedure. In both groups, the patients were older on average than those with instability from other causes. Of the primary cases, in 33 (94.3%) the cause of the first dislocation was a violent injury; six (17.4%) had evidence of damage to the rotator cuff and/or the subscapularis. Only four (11.4%) had a Bankart lesion. In patients undergoing a primary operation in whom the cause of the first dislocation was a violent injury, who did not have a Bankart lesion and had no suggestion of multidirectional laxity, the incidence of HAGL was 39%.

Adolescent↗
PubMed1998

Opinions of practicing general surgeons on surgical education.

BACKGROUND: Collective opinions of practicing general surgeons on the current state of general surgical resident education are unknown. METHODS: A 26-item survey was mailed to practicing general surgeons in Minnesota and Texas. Average scores on 17 Likert-formatted questions and opinions on multiple-choice questions were compared by geographic area and academic affiliation. RESULTS: Overall response was 954 of 1,745 (55%). All surgeons felt changes were needed in surgical education. There was agreement by geographic area and academic affiliation that the current system of resident education allows chief residents to graduate with significant gaps in their education, and that the responsibility for correcting these gaps lies with the residency program. CONCLUSIONS: Opinions of general surgeons in two geographic areas and of differing academic affiliation regarding surgical education showed marked similarity. These data suggest change in the process of surgical education is the responsibility of the residency program and should be a priority for the profession.

General Surgery↗
PubMed1997

A randomized phase III study of accelerated hyperfractionation versus standard in patients with unresected brain metastases: a report of the Radiation Therapy Oncology Group (RTOG) 9104.

PURPOSE: To compare 1-year survival and acute toxicity rates between an accelerated hyperfractionated (AH) radiotherapy (1.6 Gy b.i.d.) to a total dose of 54.4 Gy vs. an accelerated fractionation (AF) of 30 Gy in 10 daily fractions in patients with unresected brain metastasis. METHODS AND MATERIALS: The Radiation Therapy Oncology Group (RTOG) accrued 445 patients to a Phase III comparison of accelerated hyperfractionation vs. standard fractionation from 1991 through 1995. All patients had histologic proof of malignancy at the primary site. Brain metastasis were measurable by CT or MRI scan and all patients had a Karnofsky performance score (KPS) of at least 70 and a neurologic function classification of 1 or 2. For AH, 32 Gy in 20 fractions over 10 treatment days (1.6 Gy twice daily) was delivered to the whole brain. A boost of 22.4 Gy in 14 fractions was delivered to each lesion with a 2-cm margin. RESULTS: The average age in both groups was 60 years; nearly two-thirds of all patients had lung primaries. Of the 429 eligible and analyzable patients, the median survival time was 4.5 months in both arms. The 1-year survival rate was 19% in the AF arm vs. 16% in the AH arm. No difference in median or 1-year survival was observed among patients with solitary metastasis between treatment arms. Recursive partitioning analysis (RPA) classes have previously been identified and patients with a KPS of 70 or more, a controlled primary tumor, less than 65 years of age, and brain metastases only (RPA class I), had a 1-year survival of 35% in the AF arm vs. 25% in the AH arm (p = 0.95). In a multivariate model, only age, KPS, extent of metastatic disease (intracranial metastases only vs. intra- and extracranial metastases), and status of primary (controlled vs. uncontrolled) were statistically significant (at p < 0.05). Treatment assignment was not statistically significant. Overall Grade III or IV toxicity was equivalent in both arms, and one fatal toxicity at 44 days secondary to cerebral edema was seen in the AH arm. CONCLUSION: Although a previous RTOG Phase I/II report had suggested a potential benefit in patients with limited metastatic disease, a good Karnofsky performance status, or neurologic function when treated with an AH regimen, this randomized comparison could not demonstrate any improvement in survival when compared to a conventional regimen of 30 Gy in 10 fractions. Therefore, this accelerated hyperfractionated regimen to 54.4 Gy cannot be recommended for patients with intracranial metastatic disease.

Adult↗
PubMed1994

Human biodistribution and dosimetry of the SPECT benzodiazepine receptor radioligand iodine-123-iomazenil.

UNLABELLED: SPECT imaging of the brain with [123I]iomazenil has shown avid uptake of the radioligand in a distribution consistent with benzodiazepine receptor binding. The purposes of this study were to measure the whole-body distribution of activity following i.v. administration of [123I]iomazenil and to evaluate the resulting organ radiation burdens. METHODS: Serial total body scans were obtained in healthy volunteers after thyroid blockade and demonstrated avid brain uptake of radioligand. RESULTS: Abdominal imaging showed significant activity retention within the urinary and gastrointestinal tracts consistent with excretion via these routes. Absorbed dose to the urinary bladder was calculated to be 0.19 mGy/MBq, to the lower large intestine 0.079 mGy/MBq, to the upper large intestine 0.066 mGy/MBq, and to the thyroid 0.063 mGy/MBq. CONCLUSION: Thyroid uptake may in part have represented binding to benzodiazepine receptors, since radioligand binding to tissue homogenates prepared from human thyroid showed the presence of benzodiazepine binding sites.

Adult↗