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Biomedical subjects

T Johnson

Publications and source records attributed to T Johnson.

At least 127 records · Page 7Linked to original sources
PubMed1997

Use of galeal or pericranial flaps for reconstruction or orbital and eyelid defects.

The use of galeal or pericranial flaps for craniofacial reconstruction is well recognized. The excellent blood supply of the flap permits vascularized support for skin, bone, or cartilage grafts in otherwise unsatisfactory recipient sites. The pericranial flap was used in 1 patient with a large orbital bony defect and the galeopericranial flap was used in 3 patients with various periocular defects produced by trauma or following tumor extirpation. In the case of an orbital defect induced by chronic cocaine abuse, the pericranial flap successfully sequestered the orbit from the nasal cavity while providing support for the globe. In 3 of the 4 cases involving eyelid reconstruction, the galeopericranial flap served a dual function in providing vascular supply to the underlying free tarsal graft and to the overlying free skin graft. This tissue flap is analogous to a median forehead flap, except skin is not transposed and a second-stage inset revision is not required.

Adult↗
PubMed1997

Freehand full-thickness grafting for facial defects: a review of methods.

PURPOSE: This article reviews the use of full-thickness skin grafts for closure of facial defects. PATIENTS AND METHODS: In almost 3 years, 30 patients had full-thickness skin grafting after removal of premalignant or malignant facial skin lesions. The most common graft harvest sites included the preauricular and postauricular, neck, and supraclavicular areas. RESULTS: Few complications were seen except for rare surface necrosis and depression of the grafted site, and the esthetic results were generally satisfactory. CONCLUSION: Full-thickness skin grafts offer a reliable alternative to the use of flaps in selected cases.

Aged↗
PubMed1997

Prospective recruitment of women receiving prenatal care from diverse provider arrangements: a potential strategy.

OBJECTIVES: This study describes the use of a Medicaid managed care list to prospectively recruit into a research project pregnant women receiving care from a variety of providers. METHOD: A list of women enrolled in Medicaid managed care was used to recruit pregnant African-American and Latina women into a study of prenatal care satisfaction. Due to privacy concerns, the researchers were not able to directly access names from the list. Instead, a managed care contract agency sent recruitment letters to 1009 pregnant African-American and Latina Medicaid recipients. Response rates by ethnicity and several other key variables are calculated. The biases associated with this method of recruiting pregnant women from a variety of providers are discussed. RESULTS: Thirty-five percent of the women contacted returned consent forms and agreed to have researchers approach them; the response rate for African-American women was 43% and for Latinas was 29% (p < 0.0001). Respondents were younger and later in their pregnancies than nonrespondents, but did not differ from them by zip code of residence. The women recruited into the study obtained prenatal care from a diverse group of providers. CONCLUSIONS: While the use of a prospectively generated list of pregnant Medicaid recipients to recruit low-income pregnant women into a research study may be associated with some selection bias, the potential cost savings, decreased effort, and diminished recall bias may make their use a feasible sampling alternative, particularly when the researcher desires to recruit women seeking care from a variety of provider arrangements.

Adolescent↗
PubMed1997

Investigating severe neutropenia with a simple bone marrow immunofluorescence test.

Severely neutropenic patients who are suspected of having circulating autoantibodies to neutrophils and/or myeloid precursors present a diagnostic problem. This report describes the use of a simple bone marrow immunofluorescence test (BMIFT) to demonstrate autoantibodies reactive with the patient's own bands, neutrophils and myeloid precursors represented on fresh-frozen bone marrow aspirate smears. Positive results were seen in two of 13 evaluable marrows from children with primary neutropenia and in eight of 44 evaluable marrows from adults with primary or secondary neutropenia. The BMIFT is simple enough to perform in most laboratory environments and provides serological information to support a diagnosis of immune neutropenia when other means of investigation are precluded.

Adult↗
PubMed1997

Robotic solid-phase extraction of amphetamines from urine for analysis by gas chromatography-mass spectrometry.

We have evaluated the use of the Hamilton Microlab 2200 robotic pipetting system modified to conduct solid-phase extractions of amphetamines from urine. The Hamilton system is a programmable XYZ robotic sample handling instrument compatible with commercial solid-phase extraction (SPE) columns in the most commonly available sizes. During the extraction and elution steps, the system delivers programmable positive pressure with pressure controlled feedback so as to ensure consistent recovery. The system increases sample throughput while reducing technician hands-on time and improving sample-to-sample and batch-to-batch consistency. In comparison with the manual SPE method, the automated scheme provides similar analyte recovery, accuracy, and precision and a reduced potential for laboratory errors. The method's upper limits of linearity, detection, and lquantitation were, respectively, 10,000, 100, and 100 ng/mL for amphetamine and 25,000, 50, and 50 ng/mL for methamphetamine. Extraction recoveries for the compounds ranged from 88 to 101%. Carryover amounted to less than 0.02% even at 50,000 ng/mL concentrations of analyte. A typical automated run required 20 min of technician time versus 90 min for a corresponding manual SPE procedure. The automated procedure proved to be a reliable and labor-efficient addition to the laboratory.

Amphetamines↗
PubMed1997

Care management: outcomes-based practice for the primary nurse.

Managed care penetration is increasingly dramatically in most health care markets across the country. The impact is the radical redesign of health care systems and the reshaping of the approach to health care from an illness model to a wellness, health promotion model. Integrated delivery systems will facilitate the patient's journey through the continuum of care. The article describes how one institution is streamlining that journey through the integration of care management into the role of the primary nurse who provides direct care.

Cardiology Service, Hospital↗
PubMed1997

Hormonal regulation of an islet-specific enhancer in the pancreatic homeobox gene STF-1.

The homeobox protein STF-1 appears to function as a master control switch for expression of the pancreatic program during development. Here we characterize a composite enhancer which directs STF-1 expression to pancreatic islet cells via two functional elements that recognize the nuclear factors HNF-3beta and BETA-2. In keeping with their inhibitory effects on islet cell maturation, glucocorticoids were found to repress STF-1 gene expression by interfering with HNF-3beta activity on the islet-specific enhancer. Overexpression of HNF-3beta suppressed glucocorticoid receptor-mediated inhibition of the STF-1 gene, and our results suggest that the expansion of pancreatic islet precursor cells during development may be restricted by hormonal cues which regulate STF-1 gene expression.

Animals↗
PubMed1997

Peer evaluation. A visual picture.

To meet the criteria of role accountability, nursing competence and ongoing staff development, an improved peer-evaluation system was designed to continuously monitor these new roles. This peer-evaluation process converts evaluation input into data, giving staff a visual picture of how their performance compares within their peer group. This peer-evaluation process was designed as a tool to assist in staff growth and development, not as a punitive system.

Clinical Competence↗
PubMed1996

Near-infrared spectroscopy and spectral mapping of Jupiter and the Galilean satellites: results from Galileo's initial orbit.

The Near Infrared Mapping Spectrometer performed spectral studies of Jupiter and the Galilean satellites during the June 1996 perijove pass of the Galileo spacecraft. Spectra for a 5-micrometer hot spot on Jupiter are consistent with the absence of a significant water cloud above 8 bars and with a depletion of water compared to that predicted for solar composition, corroborating results from the Galileo probe. Great Red Spot (GRS) spectral images show that parts of this feature extend upward to 240 millibars, although considerable altitude-dependent structure is found within it. A ring of dense clouds surrounds the GRS and is lower than it by 3 to 7 kilometers. Spectra of Callisto and Ganymede reveal a feature at 4. 25 micrometers, attributed to the presence of hydrated minerals or possibly carbon dioxide on their surfaces. Spectra of Europa's high latitudes imply that fine-grained water frost overlies larger grains. Several active volcanic regions were found on Io, with temperatures of 420 to 620 kelvin and projected areas of 5 to 70 square kilometers.

Ammonia↗
PubMed1996

Characterization of the P2' and P3' specificities of thrombin using fluorescence-quenched substrates and mapping of the subsites by mutagenesis.

The importance of substrate residues P2' and P3' on thrombin catalysis has been investigated by comparing the hydrolysis of a series of fluorescence-quenched substrates. Each consisted of a 10-residue peptide, carrying a 2-aminobenzoyl (Abz) group at the N-terminus, and a penultimate 2,4-dinitrophenyl (Dnp) derivatized lysine. Cleavage of such a peptide relieves the intramolecularly-quenched fluorescence, allowing determination of the kinetic parameters. The nature of the P2' residue was found to have a major influence on the rate of cleavage: the Kcat/Km value for the hydrolysis of the Arg-Ser bond in Abz-Val-Gly-Pro-Arg-Ser-Phe-Leu-Leu-Lys(Dnp)-Asp-OH was nearly 3 orders of magnitude higher than that for the hydrolysis of the same substrate with aspartate instead of phenylalanine at the P2' position. Comparatively, the P3' side chain was less important: the kcat/Km value for the substrate with the least effective residue (aspartate) was only 33 times lower than that of the substrate with the most favorable amino acid (lysine). The role of thrombin residues Arg35, Lys36, Glu39 and Lys60f in the putative P2' and P3' binding sites was also examined. Replacement of Lys60f by glutamine improved the rate of cleavage for peptides with P2' lysine or leucine. Compared with thrombin, mutants E39K and E39Q hydrolyzed faster substrates with an acidic residue in P2' or P3', but slightly slower those with a lysine at either position. Mutations R35Q and K36Q only improved the hydrolysis of substrates with an acidic P2' residue. Overall, thrombin prefers bulky hydrophobic side chains in subsite S2' and positively charged residues in S3', whereas acidic residues are markedly antagonistic to both subsites.

Amino Acid Sequence↗
PubMed1996

Expression of the immunoglobulin VH gene 51p1 is proportional to its germline gene copy number.

51p1 is an immunoglobulin VH gene that is frequently expressed in B cell chronic lymphocytic leukemia and early in B cell ontogeny. The 51p1 gene locus is highly polymorphic, consisting of 13 alleles that can be classified as being either 51p1-related or hy1263-related, based on distinctive sequence motifs in the second complementarity determining region. Two of the 51p1-related genes usually occur as a linked pair on the same haopltype, resulting from gene duplication. Consequently, a person can have a total of zero to four copies of 51p1-related genes. These genes are detectable in genomic DNA by sequence-specific RFLP analysis using oligonucleotide probes. Ig encoded by nonmutated 51p1-related genes can be detected by G6, a murine antiidiotypic mAb. We have now studied lymphocytes from 35 human tonsils to examine the relation between the number of 51p1-related germlime gene copies and the proportion of IgD-bearing tonsillar B cells that react with G6. All subjects who had zero copies of 51p1-related genes lacked any G6-reactive B cells, whereas those with four copies of 51p1-related genes had the highest proportions of G6-positive IgD B cells, up to 11.4%. Subjects with intermediate gene doses had intermediate proportions of G6-reactive B cells. Over the entire data set, the percentage of IgD-bearing B cells that reacted with G6 was proportional to the 51p1-related gene copy number (r = 0.92, p < 0.001), with each copy accounting for 2.4-4.0% of the IgD-bearing B cells. We conclude that 51p1-related genes are expressed by a relatively large percentage of IgD+ tonsillar B cells and this percentage is proportional to the germline copy number of 51p1-related genes.

Adult↗
PubMed1996

Documentation patterns before cataract surgery at ten academic centers.

PURPOSE: To determine the adequacy of documenting the preoperative evaluation for cataract surgery using criteria derived from published practice guidelines. METHODS: In 1990, 1139 surgeries that were performed on 1139 patients at ten institutions of the Academic Medical Center Consortium were reviewed for completeness of documentation of the preoperative evaluation. Criteria for completeness were derived from the American Academy of Ophthalmology Preferred Practice Pattern on cataract evaluation and the Agency for Health Care Policy and Research-sponsored guidelines. RESULTS: Twenty-six percent of charts lacked documentation of at least one of four basic elements of the preoperative evaluation. These four elements are (1) vision in the surgical eye; (2) vision in the fellow eye; (3) evaluation of the fundus, macula, or visual potential in the surgical eye: and (4) presence of some form (general or specific) of functional visual impairment. If, as stated in the guideline, a specific deficit in visual functioning should be identified, then 40% of charts fail to meet criteria. CONCLUSION: Documentation of the ocular preoperative assessment for cataract surgery is inadequate in more than one quarter of cases. The relation between lack of documentation and incompleteness of the examination is unknown. Improved documentation is needed to better measure and enhance the quality of care.

Academic Medical Centers↗
PubMed1996

Vertical strabismus after cataract surgery.

PURPOSE: To compare anesthesia methods with resultant strabismus patterns in patients with vertical diplopia after cataract surgery. METHODS: The authors analyzed 28 consecutive patients with acquired vertical diplopia after cataract surgery to identify the strabismus pattern. The method of anesthesia administration was available in 21 patients. Three orbital dissections with simulated retrobulbar blocks were performed on cadavers to ascertain the possibility of injuring the vertical rectus muscles at the time of injection. RESULTS: Fifty percent of the involved muscles were overactive, 39 percent were restricted, and 11 percent were paretic. Eleven patients received retrobulbar, and ten received peribulbar anesthesia. The inferior rectus in 17 patients and the superior rectus muscle in 11 were involved. The odds of damaging the inferior rectus, as opposed to the superior rectus muscle, with peribulbar anesthesia was 4.8 times higher than with retrobulbar blocks. Cadaveric dissections showed the likelihood of direct needle injury to either vertical recti with retrobulbar blocks. CONCLUSIONS: In this patient population, permanent vertical strabismus after cataract surgery results more often from overacting or restricted muscles than from primary muscle paresis. Both the superior and inferior recti can be injured with retrobulbar anesthesia, but peribulbar injections affect the inferior rectus muscle more frequently.

Anesthesia, Local↗