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Biomedical subjects

R Johnson

Publications and source records attributed to R Johnson.

At least 253 records · Page 14Linked to original sources
PubMed1994

Grease gun injuries to the orbit and adnexa.

The grease gun injury is an uncommon injury to the orbit. However, high-pressure injection of grease, oil, or paint is frequently reported in injuries of the hand and usually affects the fingers or palm, which require complicated surgical and medical care. Two cases of grease gun injury to the orbit are reported: one, a catastrophic injury, and the other resulting in satisfactory recovery after surgical debridement and adjuvant medical treatment. Presentation, investigation, and therapy are discussed.

Accidents, Occupational↗
PubMed1994

Pacing system analyzers: different systems--different results.

When a pacemaker is implanted, several electrophysiological parameters are measured using pacing system analyzers (PSA). Different PSAs may use different filter settings and measuring techniques when compared to the implanted pacemaker. In order to determine if there were significant differences in measurements obtained with different PSAs, we obtained measurements in a group of 99 patients with three different PSAs and a manual method. The results show that with each of the three different PSAs tested, different amplitudes of intracardiac electrograms are obtained and that they are usually higher than those obtained by manual measurement of recorded electrograms. Despite significant differences, however, all methods correlate well with each other. Following common practice of pacemaker programming, the use of a PSA for the implantation of a pacemaker that uses different sensing technique does not lead to clinical complications.

Humans↗
PubMed1994

Genetics and molecular biology of mouse pigmentation.

The formation of mouse coat color is a relatively complex developmental process that is affected by a large number of mutations, both naturally occurring and induced. The cloning of the genes in which these mutations occur and the elucidation of the mechanisms by which these mutations disrupt the normal pigmentation pattern is leading to an understanding of the way interactions between gene products lead to a final phenotype.

Amino Acid Sequence↗
PubMed1994

Evaluation of the relative sensitivity of chromosome painting (FISH) as an indicator of radiation-induced damage in human lymphocytes.

Fluorescence in situ hybridization with whole chromosome libraries, also known as chromosome "painting", is an easy and rapid method for detection of chromosome aberrations. To evaluate the sensitivity of this in radiation dosimetry we have made comparisons with G-banding analysis and also with physicochemical measurements of radiation induced DNA damage (DNA strand breaks and 8-hydroxydeoxyguanosine formation). Heparinised human blood was irradiated at room temperature with a range (0-10 Gy) of gamma irradiation from a cobalt 60 source. Chromosome spreads prepared from phytohaemagglutinin stimulated "whole blood" lymphocyte cultures were hybridized in situ with the whole chromosome 1 library, coded, and scored for aberrant cells. Dose response curves plotted as percent abnormal cells obtained by the two cytogenetic methods were similar and it would appear that chromosome "painting" compared favourably with G-banding for the detection of aberrations. The measurement of DNA strand breaks by a fluorimetric alkaline unwinding assay showed similar sensitivity to chromosome "painting" whereas the formation of 8-hydroxydeoxyguanosine did not correlate with aberration frequencies.

Adult↗
PubMed1994

Magnetic resonance imaging functional activation of left frontal cortex during covert word production.

Six normal volunteers underwent 4-T functional magnetic resonance imaging while performing a covert letter fluency task. An echo planar imaging sequence was utilized to detect activation based on deoxyhemoglobin contrast. All 6 subjects showed consistent activation in the frontal operculum and premotor and primary motor cortices. Activation was also detected in the supramarginal gyrus and the posterior part of the superior temporal gyrus. These results show that magnetic resonance functional neuroimaging can be used to investigate cerebral activity noninvasively during performance of complex cognitive tasks.

Adult↗
PubMed1994

Cavitary coccidioidomycosis with fungus ball formation. Diagnosis by fiberoptic bronchoscopy with coexistence of hyphae and spherules.

Pulmonary cavitary coccidioidomycosis with fungus ball formation was observed in two individuals with hemoptysis. The first patient had no overt compromise; the second was an insulin-dependent diabetic. In both, fiberoptic bronchoscopy was performed and cultures yielded Coccidioides immitis. The coexistence of spherules and hyphae of C immitis was seen histologically on bronchoscopic biopsy specimen of one cavitary lesion. Specific antifungal therapy and surgical excision were withheld and each patient has done well. This report provides for the first time nonsurgical confirmation that C immitis can produce an intracavitary fungus ball.

Adult↗
PubMed1994

Interface gateways: defining the solutions.

In summary, an interface gateway is able to quickly create and support relationships. In the healthcare environment of the 1990s, organization executives will be faced with an exponential increase in the number of provider, payor and employer alliances, affiliations and acquisitions. One of the recurring requirements in this scenario is the need to share information. Most of the data standards in existence today do not address the vast interface requirements of these organizations. However, the capabilities, flexibility and capacity of interface gateways can allow these relationships to be created and supported in a fraction of the time that conventional methods require.

Computer Communication Networks↗
PubMed1994

The collateral ligament flexion-extension test (CLEFT) in total knee replacement.

We present a simple preoperative clinical test, the collateral ligament extension-flexion test (CLEFT). In patients undergoing total knee arthroplasty, with a preoperative valgus or varus deformity, this test establishes which knees have balanced collateral ligaments. It predicts which knees will not require soft tissue adjustment during the course of their surgery despite, in some cases, large deformities. The mechanism of the test is based on the observation that, in certain patients, a deformity present in extension is seen to correct in flexion. The sensitivity of this observation was checked in 44 consecutive patients undergoing total knee arthroplasty, and who had either a valgus or varus deformity in extension greater than 10 degrees. In 34 patients the test was positive, and none of these required ipsilateral collateral ligament release. All of the 10 patients with a negative test required soft tissue adjustment. In patients undergoing unconstrained total knee arthroplasty this test is reliably predictive of those knees with preoperative deformity which can be corrected simply by correctly aligned bone cuts. It supports the principle of bony resection prior to soft tissue adjustment in this form of surgery.

Biomechanical Phenomena↗
PubMed1994

The hedgehog gene family in Drosophila and vertebrate development.

The segment polarity gene hedgehog plays a central role in cell patterning during embryonic and post-embryonic development of the dipteran, Drosophila melanogaster. Recent studies have identified a family of hedgehog related genes in vertebrates; one of these, Sonic hedgehog is implicated in positional signalling processes that show interesting similarities with those controlled by its Drosophila homologue.

Amino Acid Sequence↗
PubMed1994

Tissue disposition of 26aluminum in rats measured by accelerator mass spectrometry.

A trace quantity of 26aluminum (26Al) was administered intravenously to 1 normal and 1 uremic rat. After a 3-week period, the animals were sacrificed and samples of bone, muscle, kidney, liver, heart, and brain were analyzed for their 26Al content. In the normal and uremic rats, most of the tissue 26Al was found in bone amounting to 0.9% and 2.0%, respectively, of administered dose/g dry weight of tissue. Much smaller amounts of isotope were found in the other tissues in both animals. In the normal rat, the descending order of 26Al content in other tissues was: kidney, 0.2% > liver, 0.06% > heart, 0.03%, > brain and muscle, 0.02%. In the uremic rat, the same order of tissue 26Al content was found with kidney, 0.37% > liver, 0.06% > heart, 0.02% > brain and muscle, 0.01% per g dry weight of tissue. When expressed per g wet weight of tissue in the 2 animals, a similar order of tissue 26Al content was found. In comparing the amount of 26Al in the bone of the 2 rats, the uremic animal was found to have more than twice that found in the bone of the normal rat when expressed either per g dry or wet weight of bone. However, 26Al content of other tissues was similar in the 2 animals. This suggests that uremic bone may have a greater affinity for aluminum than normal bone, but kidney, liver, brain, heart, and muscle appear to behave similarly in uremic and normal rats in regard to incorporation of a single trace dose of isotope in the 3-week time frame of the present study.

Aluminum↗
PubMed1994

Improved response to erythropoietin in peritoneal dialysis patients as compared to hemodialysis patients: role of iron deficiency.

Various studies have shown that peritoneal dialysis patients may require less erythropoietin (rHuEPO) than maintenance hemodialysis patients. Iron deficiency in hemodialysis patients may contribute to the difference in response. This study compares the response to rHuEPO in 24 patients on CAPD to 33 patients on hemodialysis. All the hemodialysis patients received intravenous iron to prevent iron deficiency. Peritoneal dialysis patients received rHuEPO subcutaneously twice weekly. Erythropoietin was administered intravenously thrice weekly in hemodialysis patients. In peritoneal dialysis patients, hematocrit was 23.1% and 30.1%, rHuEPO dose was 80.9 and 89.0 u/kg/wk, while in hemodialysis patients hematocrit was 22.2% and 31.2%, and rHuEPO dosage was 140.2 and 154.3 u/kg/wk at initiation, and six months after therapy (p < 0.05 for dose, hemodialysis vs CAPD). Serum iron and transferrin saturation remained normal both in peritoneal and hemodialysis patients. These findings suggest that hemodialysis patients require a higher dosage of rHuEPO than peritoneal dialysis patients for a comparable rise in hematocrit, even when iron deficiency is prevented with parenteral iron. The improved efficacy of rHuEPO in CAPD patients may be due to the better removal of the inhibitors of erythropoiesis and/or the subcutaneous route of administration.

Anemia↗
PubMed1994

The West Point Study: 40 years of follow-up.

Completion of cardiovascular evaluations of 387 members marked the end of 40 years of follow-up in the West Point Study. Coronary artery disease (CAD) caused 4 cases of sudden death, 14 cases of myocardial infarction (MI), 13 cases of angina, and 17 cases of silent CAD. Using risk factors (serum cholesterol, estimated HDL-cholesterol, systolic blood pressure, and smoking status) measured before age 28, we derived a multivariate regression formula for predicting which members of the study, had they been pilots, would have been grounded for CAD before age 55. This derivation used data from only those subjects with CAD or with no evidence of CAD. We then used the formula to compute a risk-related score for each member of the study. In the tertile group with the highest risk-related scores, 17% manifested CAD by age 55 and the first event occurred at age 39. In the tertile group of lowest scores, 2% experienced CAD by age 55 and the first event occurred at age 51. We conclude that it is possible to select pilot candidates with the lowest risk for CAD.

Adult↗
PubMed1994

Advancing clinical excellence: competency-based patient care.

A competency-based patient care program was developed to measure current levels in staff nurses. Use of evaluative tools designed on site has resulted in: 1) Development of a credentialing and privileging process which meets JCAHO requirements; 2) Planning of an educational calendar based on identified needs; 3) Strengthening the foundations of the nursing career ladder; 4) Overall team building which integrates nurses with other healthcare professionals; and 5) Improved patient care.

Clinical Competence↗
PubMed1994

Cell-to-cell communication in a differentiating ovine lens culture system.

PURPOSE: This study was performed to determine whether the junctions between both the epithelial and the differentiating fiber-like cells of ovine lens cultures, like gap junctions in other tissues, exhibit cell-to-cell communication that is inhibited by n-octanol, and to determine whether lens connexins and the fiber cell membrane proteins MP20 and MP26 are expressed by these ovine lens cell cultures. METHODS: Cells were injected with Lucifer yellow CH to measure cell-to-cell communication. Antibodies to connexin-related lens membrane protein MP70, connexin 43 (Cx43), and connexin 46 (Cx46) and to membrane proteins MP20 and MP26 were used to immunofluorescently label lens cultures and probe Western blots of membranes isolated from lens cultures. RESULTS: Both epithelial cells and differentiating clear cells exhibited cell-to-cell transfer of Lucifer yellow that was inhibited by n-octanol. Although a Cx43 antibody immunofluorescently labeled small plaques between the epithelial cells, an MP70 antibody labeled large plaques as well as small punctate areas of the differentiating fiber-like cells. It is interesting that Cx43 and MP70 were frequently present in the same plaques at cell interfaces between epithelial cells as well as some of the larger plaques on the differentiating fiber-like cells. Cx46 and MP70 antibodies labeled the same plaques in membranes of differentiating fiber-like cells and late-stage epithelial cells. The electrophoretic mobility of all three connexin proteins was modified after treatment with alkaline phosphatase. Immunohistochemical staining of these differentiating regions and Western immunoblotting of purified membranes derived from differentiated cultures also showed the presence of MP20 and MP26. CONCLUSIONS: The different cell types in the ovine lens culture exhibit gap junction-mediated cell-to-cell communication that is likely effected by one or more of the connexin proteins.

1-Octanol↗
PubMed1993

Accessory molecules involved in antigen-mediated cytolysis and lymphokine production by cytotoxic T lymphocyte subsets. I. Identification of functions for the T cell surface molecules Ly-6C and Thy-1.

The murine T cell surface molecules Ly-6C and Thy-1 are genetically and structurally distinct, yet they share two interesting properties: both are attached to the plasma membrane through a glycophosphatidylinositol linkage, and some mAb reactive with these molecules can activate T cells. Although mAb for Ly-6C and Thy-1 appear to mimic the function of physiologic ligands, direct evidence for the existence of these putative ligands has not been presented. In this report, we describe CTL clones that use Ly-6C and Thy-1 as accessory molecules for activation of cytolysis and the production of IFN-gamma based on inhibition of these functions with mAb. These studies were facilitated by the derivation of a nonactivating hamster IgM mAb specific for Ly-6C. CTL clones that use Ly-6C and Thy-1 as accessory molecules include a subpopulation of the previously described CD8+ alloreactive CTL that are not inhibited by mAb reactive with CD8, a CD8+ TCR-alpha/beta+ T cell clone specific for HSV glycoprotein D, and a CD4-CD8- TCR-gamma/delta+ T cell clone specific for HSV glycoprotein I. The role of Ly-6C and Thy-1 in target cell recognition is to some degree tissue-specific with respect to the APC/target cell. A mAb specific for Ly-6C appears to inhibit activation by prevention of adhesion between the effector cells and the target cells. This is the most direct evidence to date of a functional ligand for Ly-6C.

Animals↗
PubMed1993

Relationship of C5a receptor modulation to the functional responsiveness of human polymorphonuclear leukocytes to C5a.

The relationship of C5a receptor expression on human polymorphonuclear leukocytes (PMN) to the functional response of these cells to C5a was studied using flow cytometry. C5a receptor expression was determined with a fluorescein conjugate of C5a and oxidative burst activity was monitored by conversion of dichlorofluorescein to dichlorofluorescein (DCF) as a measure of H2O2 production. These studies showed that after incubation of PMN with increasing concentrations of C5a, and allowing for internalization of bound ligand, more than 40% of the cell surface C5a receptors were internalized before the DCF response to optimal concentrations of C5a was decreased below the levels for untreated control cells. Although C5a responsiveness was lost after preincubation with 10(-8) M C5a, cells remained responsive to formyl peptide. In other studies, cells were preincubated with unlabeled C5a under conditions that provided for internalization of nearly all C5a receptors. PMN were then cultured for up to 90 min and monitored for C5a receptor reexpression and return of cell function. In these studies, the DCF response of PMN to C5a returned to 100% much earlier than the cells regained full expression of C5a receptors. The DCF response to formyl peptide remained intact throughout the period of C5a receptor reexpression. These studies showed that once > 40% of the original population of C5a receptors are reexpressed on the PMN, that these cells regain 100% of their functional responsiveness to C5a in the DCF assay. Evaluation of the affinity and number of C5a receptors using 125I-labeled C5a after receptor reexpression showed that maximal receptor reexpression was approximately 73% of that obtained with control cells and the Kd of reexpressed receptors was 0.60 vs 0.94 nM for control cells. These studies demonstrate that only a portion of the total C5a receptors expressed on PMN are essential to stimulate a 100% functional response in PMN and that the reexpressed receptors are capable of transducing a signal that activates the oxidative burst in these cells.

Complement C5a↗