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G Johnson

Publications and source records attributed to G Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1999

Random length assortment of human and mouse T cell receptor for antigen alpha and beta chain CDR3.

In view of the recently determined three-dimensional structures of complexes formed by the T cell receptor for antigen (TCR), the processed peptide and the MHC class I molecule, it is expected that the combined configuration formed by the third complementarity determining regions (CDR3) of TCR alpha and beta chains will be very restricted in size and shape due to the limited length variations of the processed peptides. Thus, the combined TCR alpha and beta chain CDR3 lengths should have a fairly narrow distribution. This feature can be due to the selective association of long alpha chain CDR3 with short beta chain CDR3 and vice versa or due to random assortment of alpha and beta chain CDR3 of even narrower length distribution. Based on existing translated amino acid sequence data, it has been found that the latter mechanism is responsible.

Amino Acid Sequence↗
PubMed1999

Causes and prevalence of non-vision impairing ocular conditions among a rural adult population in sw Uganda.

Information is scanty about the extent of ocular morbidity in developing countries, particularly for non-vision impairing conditions (NVIC), although these constitute the majority of consultations in eye clinics. We have conducted a survey to determine the prevalence and causes of NVIC in a Ugandan adult population and compared our findings with the work pattern of the district hospital. Adults were screened using Snellen's illiterate E chart and those found with visual impairment (acuity less than 6/18) in either eye were referred to a low-vision clinic, and those with obvious ocular disease or symptoms, but without visual impairment, to an outreach clinic. A total of 2886 (53%) out of 5479 adults were screened. Of these, 257 (8.9%) were referred to the outreach clinic, of whom 173 (67%) attended. Of those attending the low-vision clinic 83% had visual impairment confirmed, and 92% of those attending the outreach clinic were confirmed not to have visual impairment. The four commonest NVIC observed at the outreach clinic were: presbyopia (48%), allergic conjunctivitis (20%), early cataract (9%) and infective conjunctivitis (8%), the same conditions as those most commonly seen at the district hospital. In this community, over 80% of NVIC are caused by four conditions which are potentially either correctable, operable or treatable. Training health workers to recognise and treat these conditions would serve the great majority of eye patients. Hospital activity data can be used cautiously to assess the relative frequency of NVIC in the community.

Adolescent↗
PubMed1999

An exploration of the sequence of a 2.9-Mb region of the genome of Drosophila melanogaster: the Adh region.

A contiguous sequence of nearly 3 Mb from the genome of Drosophila melanogaster has been sequenced from a series of overlapping P1 and BAC clones. This region covers 69 chromosome polytene bands on chromosome arm 2L, including the genetically well-characterized "Adh region." A computational analysis of the sequence predicts 218 protein-coding genes, 11 tRNAs, and 17 transposable element sequences. At least 38 of the protein-coding genes are arranged in clusters of from 2 to 6 closely related genes, suggesting extensive tandem duplication. The gene density is one protein-coding gene every 13 kb; the transposable element density is one element every 171 kb. Of 73 genes in this region identified by genetic analysis, 49 have been located on the sequence; P-element insertions have been mapped to 43 genes. Ninety-five (44%) of the known and predicted genes match a Drosophila EST, and 144 (66%) have clear similarities to proteins in other organisms. Genes known to have mutant phenotypes are more likely to be represented in cDNA libraries, and far more likely to have products similar to proteins of other organisms, than are genes with no known mutant phenotype. Over 650 chromosome aberration breakpoints map to this chromosome region, and their nonrandom distribution on the genetic map reflects variation in gene spacing on the DNA. This is the first large-scale analysis of the genome of D. melanogaster at the sequence level. In addition to the direct results obtained, this analysis has allowed us to develop and test methods that will be needed to interpret the complete sequence of the genome of this species. Before beginning a Hunt, it is wise to ask someone what you are looking for before you begin looking for it. Milne 1926

Alcohol Dehydrogenase↗
PubMed1999

Determinants of attendance and patient satisfaction at eye clinics in south-western Uganda.

PURPOSE: To identify the reasons for subjects deciding to attend or not attend local and referral ophthalmology clinics in south-west Uganda, and to establish the levels of satisfaction of clinic attenders with the services they received. METHODS: A population survey identified subjects with ocular conditions who were referred to the local clinic or the district hospital. All non-attenders and a group of attenders were interviewed at home. RESULTS: 31% of those referred did not attend the local clinic. The most common reasons were 'too busy' (29%) or 'unwilling to buy spectacles' (17%). Less than half of attenders were satisfied, mainly because of no perceived clinical improvement or having to buy spectacles. Only 13% of those referred to the district hospital clinic attended. The main reasons for non-attendance were high transport cost and fear of the clinic. CONCLUSION: Attendance and satisfaction with the community ophthalmology service could be improved by more intensive motivation and explanation for patients, and assistance with spectacle and transport costs. The use of aphakic motivators should be tested in this context.

Community Health Centers↗
PubMed1999

The Influence of Background Music on Task Engagement in Frail, Older Persons in Residential Care.

Colmery-O'Neil Veterans Affairs Medical CenterThe purpose of this study was to examine the effects of preferred background music on the engagement of residents of a nursing care facility in therapeutic recreation tasks. Eighteen subjects were assigned to one of two groups and both groups participated in a series of 12 weekly sessions in which the background conditions were randomly ordered. All subjects experienced four sessions each of 10 minutes of (a) silence, (b) preferred background music, and (c) nonpreferred background music. Videotapes were made of all sessions and an observer recorded the number of 30-second time intervals in which each subject was on task. A one-way analysis of variance calculated for frequencies of time intervals for the three conditions revealed no statistically significant differences. It was noted, however, that the therapist tended to prompt more conversations during the preferred music, and when subjects responded they generally dropped their task participation. The investigators concluded that background music may influence the therapists' behaviors which may, in turn, influence responses of their program participants. Further study of the effects of background music on task engagement among care home residents is recommended.

Journal Article↗
PubMed1999

Early North American research on lithium.

Research and clinical interest in lithium in the USA lagged behind that in Europe, largely because of the experience of deaths due to lithium in cardiac patients. The first American report on lithium was published in 1960 by Sam Gershon, the Australian psychiatrist who had undertaken lithium studies in Melbourne in conjunction with the physiologist Trautner. Major USA clinical trials originated in the 1960s; and the clinical significance of lithium was recognised in a special section in the American Journal of Psychiatry in 1968. The US Food and Drug Administration (FDA) approval of lithium for control of manic episodes was finally given in 1970.

Antimanic Agents↗
PubMed1999

A comprehensive care clinic in Swedish dental undergraduate education: 3-year report.

In 1993, a new undergraduate curriculum was introduced at the Faculty of Dentistry, Karolinska Institute. The expanded comprehensive care clinic described in this 3-year report, is proposed as a potential model for a CC-clinic in dental undergraduate education. Students enter clinical training at the beginning of the 3rd year and continue through to their final semester, in the 5th year. The one student is responsible for the total oral care of all his/her patients. Patients are stratified on admission into 3 levels, depending on the complexity of treatment need. Before being assigned their 1st patients (patient level I), the students must fulfil specified requirements of theoretical knowledge and clinical procedures and obtain a proficiency certificate. After qualifying for higher proficiency certificates, denoting their level of clinical responsibility, the students assume successively greater responsibility for treatment of patients, with less supervision from clinical instructors. Clinical supervision is the responsibility of integrated multidisciplinary teams of faculty members. Each group of students is assigned a clinical tutor, who is responsible for overall treatment planning of their patients. The individual student's clinical progress and achievements are monitored by a specially designed computer program. Criteria for a final pass in the course are: (1) clinical maturity in overall patient management; (2) technical competence in conjunction with theoretical knowledge. 3 years experience of the new model for comprehensive clinical training in a patient-centred, multidisciplinary clinic has shown that; (a) students seem to acquire a greater understanding of comprehensive case management; (b) patients receive more co-ordinated care; (c) there has been no significant change in the number of clinical procedures completed; (d) difficulties arise in co-ordination of staff over the traditional specialist boundaries; (e) assessment of student maturity and professional responsibility is impeded by the lack of objective criteria.

Clinical Competence↗
PubMed1999

Glial neoplasms: dynamic contrast-enhanced T2*-weighted MR imaging.

PURPOSE: To evaluate the role of T2*-weighted echo-planar perfusion imaging by using a first-pass gadopentetate dimeglumine technique to determine the association of magnetic resonance (MR) imaging-derived cerebral blood volume (CBV) maps with histopathologic grading of astrocytomas and to improve the accuracy of targeting of stereotactic biopsy. MATERIALS AND METHODS: MR imaging was performed in 29 patients by using a first-pass gadopentetate dimeglumine T2*-weighted echo-planar perfusion sequence followed by conventional imaging. The perfusion data were processed to obtain a color map of relative regional CBV. This information formed the basis for targeting the stereotactic biopsy. Relative CBV values were computed with a nondiffusible tracer model. The relative CBV of lesions was expressed as a percentage of the relative CBV of normal white matter. The maximum relative CBV of each lesion was correlated with the histopathologic grading of astrocytomas obtained from samples from stereotactic biopsy or volumetric resection. RESULTS: The maximum relative CBV in high-grade astrocytomas (n = 26) varied from 1.73 to 13.7, with a mean of 5.07 +/- 2.79 (+/- SD), and in the low-grade cohort (n = 3) varied from 0.92 to 2.19, with a mean of 1.44 +/- 0.68. This difference in relative CBV was statistically significant (P < .001; Student t test). CONCLUSION: Echo-planar perfusion imaging is useful in the preoperative assessment of tumor grade and in providing diagnostic information not available with conventional MR imaging. The areas of perfusion abnormality are invaluable in the precise targeting of the stereotactic biopsy.

Adolescent↗
PubMed1999

Thoracic aorta: rapid black-blood MR imaging with half-Fourier rapid acquisition with relaxation enhancement with or without electrocardiographic triggering.

PURPOSE: To evaluate and compare findings for thoracic aortic disease with three black-blood magnetic resonance (MR) pulse sequences: half-Fourier rapid acquisition with relaxation enhancement (RARE), with and without electrocardiographic (ECG) triggering, and ECG-triggered turbo spin echo (SE). MATERIALS AND METHODS: Axial black-blood MR images of the chest acquired at 1.5 T with a phased-array coil were obtained in 38 consecutive patients referred for evaluation of thoracic aortic disease. ECG-triggered and nontriggered half-Fourier RARE images were compared with T1-weighted ECG-triggered turbo SE images. Two readers independently scored images for each of the following parameters: ghosting artifacts; clarity of the mediastinum, cardiac chambers, and aortic wall; conspicuity of abnormality; intraluminal signal void uniformity; and overall image quality. RESULTS: Both half-Fourier RARE sequences outperformed the turbo SE sequence for all measured parameters. Scores for the ECG-triggered half-Fourier RARE sequence were significantly (P < .05) higher than those for the nontriggered version for clarity of the mediastinum and aortic wall, conspicuity of any abnormality other than aortic dissection, and overall image quality. Mean acquisition times for the ECG-triggered (48 seconds) and nontriggered (30 seconds) sequences were significantly shorter than that for the turbo SE sequence (2 minutes 20 seconds). CONCLUSION: Rapid black-blood half-Fourier RARE sequences, with or without ECG triggering, can replace ECG-triggered turbo SE sequences for evaluation of thoracic aortic disease.

Adult↗
PubMed1999

Cell interactions with perfluoropolyether-based network copolymers.

We have investigated the potential of several polymers based on perfluoropolyether (PFPE) macromonomers for use in biomaterial applications. Polymer networks were synthesised from the PFPE macromonomers of increasing chain length and the adhesion and proliferation of corneal, vascular and bone cells was evaluated on these polymers. The polymer surfaces were quite hydrophobic, having sessile air-water contact angles ranging between 96 and 125 degrees. However, these polymers supported the attachment and growth of bovine corneal epithelial and endothelial cells and fibroblasts at 60-100% of the rate of cell growth on the culture substratum, TCPS. Furthermore, the PFPE polymers supported the attachment and growth of vascular endothelial cells (from human umbilical artery) and human bone-derived cells over a 7 day period at an equal level to TCPS. The relationship between the macromonomer chain length (n = 1 to 4) and the ability of the resulting PFPE homopolymer to support the overgrowth of corneal epithelial tissue was also evaluated. The PFPE-containing polymers supported corneal epithelial tissue overgrowth, with the most effective having a performance equivalent to that of TCPS. In addition to these homopolymers, copolymers comprising of PFPE and N,N-dimethylaminoethyl methacrylate (DMAEMA) were also synthesised. Surprisingly, the addition of DMAEMA to the PFPE polymer network lead to a reduction in the growth and attachment of corneal epithelial cells and fibroblasts. These results indicate that PFPE-based materials show a potential for use in the development of biomaterials in the ocular, vascular and orthopaedic areas.

Animals↗
PubMed1999

Etiology of Dupuytren's disease.

The etiology of Dupuytren's disease is still unknown in spite of significant recent advances in identifying the type of cell responsible for initiating the process. Associated factors such as alcoholism, smoking, work, diabetes, and epilepsy are discussed. The course of the disease in men as compared with women is also discussed. Recent evidence has shown that there may be genetic and immunologic factors involved. Superoxide free radicals and their effect on fibroblast proliferation may play a significant role in the disease process.

Alcoholism↗
PubMed1999

Development of a radiopharmaceutical information database.

OBJECTIVE: This article describes the development of a radiopharmaceutical (RP) computer database. Development and implementation of the database and services provided are presented. METHODS: A commercial database program was used to develop the structure for a radiopharmaceutical information database (RID) and to classify interaction information into several categories. The database is accessible to a variety of users through a network server. RESULTS: Information entered into the RID may be accessed easily and rapidly. The RID provides a wide spectrum of information services to its customers. CONCLUSION: The RID described is the first attempt to develop a database capable of entry and retrieval of RP information in an efficient and timely manner. The database is easy to use and maintain, and has virtually unlimited storage space on a network drive.

Database Management Systems↗
PubMed1999

Splenic rupture associated with severe preeclampsia. A case report.

BACKGROUND: Splenic rupture is a very rare event complicating pregnancy. Approximately 5% of cases reported have involved the postpartum period. Unrecognized, this complication is universally fatal. CASE: Preeclampsia and pulmonary edema complicated a 42-year-old woman's intrapartum care. After cesarean delivery she was supported with mechanical ventilation, blood products and invasive monitoring. Shortly thereafter, she became hypotensive and developed disseminated intravascular coagulation. During exploratory laparotomy a splenic capsular rupture was identified. Splenectomy and continued intensive care support ultimately reversed the severe end-organ consequences. CONCLUSION: It is extremely important that this condition be maintained in the diagnostic differential of post-operative hemodynamic instability. Failure to identify it is invariably fatal. Awareness and intervention are essential to ensure a good outcome.

Adult↗
PubMed1999

Increasing gap in breast cancer mortality between black and white women.

Breast cancer mortality rates have declined in the United States and in Wisconsin. We examined racial differences in mortality trends among black and white women in Wisconsin and the United States from 1979 to 1996. During this time period, mortality rates increased 10% among black women and decreased 7% among white women in Wisconsin. These trends were similar nationally, with an 18% increase among black women and a 3% decrease among white women. The black:white gap in mortality increased among women of all ages--especially among women under age 55. The increasing racial disparity in breast cancer mortality may result from differences in trends in incidence and survival among black women. More research is needed to understand the underlying causes of the disparity in breast cancer mortality between black and white women.

Adult↗
PubMed1999

Pulmonary silicosis in three North American river otters (Lutra canadensis).

Three adult female North American river otters (Lutra canadensis) demonstrated severe anesthetic complications shortly after being immobilized for dental procedures. Two of the animals died shortly after anesthesia, and the third otter died 2 mo after immobilization. All three animals were diagnosed with pulmonary silicosis on the basis of histopathology, polarized light microscopy, and mass spectrometry. One animal also had primary pulmonary bronchoalveolar carcinoma. Significant concurrent disease was not found in other organs. Analysis of the lung tissue by laser microbe mass spectrometry confirmed the presence of an aluminum silicate in the lung tissue associated with insulation material used in nest box construction.

Aluminum Silicates↗
PubMed1998

AMP-activated protein kinase is activated by low glucose in cell lines derived from pancreatic beta cells, and may regulate insulin release.

The role of the AMP-activated protein kinase (AMPK) cascade in the glucose-sensitive pancreatic beta cell lines HIT-T15 and INS-1 was addressed. In both cell types, removal of glucose leads to a >5-fold activation of AMPK activity. Activation of AMPK was due to phosphorylation, since the effect was reversed by protein phosphatase treatment of the extracts, and was restored by re-addition of MgATP and the purified upstream kinase. When the effects of different concentrations of medium glucose were examined, insulin secretion and AMPK activity were inversely related, and varied over the same concentration range. The activation in response to glucose removal appeared to be due to changes in the concentration of the known regulators of the cascade, i.e. AMP and ATP, since AMPK activation was associated with a large increase in the cellular AMP/ATP ratio, and the two parameters varied over the same range of glucose concentrations. In late-passage HIT-T15 cells that had lost the glucose-dependent insulin secretion response, both AMPK activity and the AMP/ATP ratio also became insensitive to the extracellular glucose concentration. Treatment of INS-1 cells, but not HIT-T15 cells, with AICA riboside (5-aminoimidazole-4-carboxamide riboside) results in accumulation of the ribotide, ZMP (AICA riboside monophosphate), and activation of AMPK. AICA riboside treatment of INS-1 cells, and of isolated rat islets, had both inhibitory and stimulatory effects on insulin secretion. These results show that in beta cell lines the AMP-activated protein kinase, like its yeast homologue the SNF1 complex, can respond to the level of glucose in the medium, and may be involved in regulating insulin release.

AMP-Activated Protein Kinases↗
PubMed1998

Effects of brain endogenous insulin on neurofilament and MAPK in fetal rat neuron cell cultures.

We demonstrated the 'de novo' synthesis of insulin within the fetal nervous system in vivo and in vitro. We undertook this study to show a role for brain endogenous insulin within the fetal brain. We used neuron cell cultures (NCC) from 19 days gestational age fetal rat brains incubated in an insulin free/serum free defined medium. The neurons showed the presence of preproinsulin I and II mRNA using polymerase chain reaction and insulin immunoreaction employing peroxidase anti-peroxidase and radioimmunoassay techniques. Using an anti-pan neurofilament antibody (that recognizes non-phosphorylated neurofilaments) neurofilament immunoreaction (NFI) was observed within the neuron body, dendrites and axon. Either insulin antibody or isoproterenol treatment induced the neurites to retract and most of the neurons become round, with NFI confined to the neuron body. The antibody treatments induced the neurons to become hypertrophic and vacuolated. With PD98059 treatment NFI was only observed within the neuron body. The addition of insulin reversed the effects of isoproterenol and PD98059, but not those of the insulin antibody. Treatment with wortmannin had no effect. Western blot analysis showed that the basal level of mitogen activated protein kinase (MAPK) phosphorylation was inhibited by the treatment of the NCC with isoproterenol or trypsin, but was significantly increased by treatment with exogenous insulin, demonstrating that brain endogenous insulin phosphorylated MAPK (p<0.05). Thus, brain endogenous insulin promotes neurite outgrowth, probably via MAPK and by stimulating neurofilament distribution via this mechanism participates in neuron differentiation.

Animals↗