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Biomedical subjects

K R Rogers

Publications and source records attributed to K R Rogers.

30 records · Page 2Linked to original sources
PubMed1989

Acetylcholine receptor fiber-optic evanescent fluorosensor.

An acetylcholine receptor-based optical biosensor was developed, which uses the evanescent wave to excite fluorescein isothiocyanate-labeled alpha-bungarotoxin (FITC-alpha-BGT), that is bound to a receptor protein immobilized on the surface of a quartz fiber. After excitation of the fluorophore just outside the waveguide boundary, the resultant fluorescence was trapped by and propagated back up the fiber. Pure nicotinic acetylcholine receptor (nAChR) protein, isolated from Torpedo electric organ, was immobilized noncovalently on quartz optic fibers and its density was quantitated by 125I-BGT binding. In the absence of nAChR, FITC-alpha-BGT alone bound to the quartz fiber. This nonspecific (i.e., nonreceptor) binding of FITC-alpha-BGT was totally eliminated by the addition of 0.1 mg/ml bovine serum albumin to the phosphate-buffered saline medium. This solution did not interfere with FITC-alpha-BGT binding to the nAChR that was immobilized on the fiber. Thus, only specific binding was observed under these conditions, resulting in a very high signal-to-noise ratio of greater than 99. Specific FITC-alpha-BGT binding to the nAChR protein on the optic fibers was inhibited by agonists (e.g., acetylcholine, nicotine, and carbamylcholine) and antagonists (e.g., pancuronium and d-tubocurarine) of the nAChR and was insensitive to high salt concentrations (e.g., 154 mM NaCl). The binding was most sensitive to the highly nAChR-specific alpha-BGT and alpha-cobratoxin. The optic-fiber sensor in its present form does not distinguish between receptor agonists or antagonist and cannot be regenerated for repeated use.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Using OKT3 to reverse cardiac allograft rejection.

Acute rejection is the major impediment to long-term patient survival after organ transplantation. Historically, the treatment of cardiac allograft rejection has been use of cytotoxic agents combined with high-dose steroids, resulting in an increased incidence of undesirable side effects. A new agent, OKT3, appears to be capable of reversing acute rejection episodes without significant morbidity. We report 10 cardiac transplant recipients in whom acute rejection was dramatically reversed and clinical symptoms resolved after treatment with OKT3. Side effects were minimal, including febrile episodes, innocuous diarrheal syndromes, mild opportunistic infections, and one hypotensive episode. Critical care nurses administering OKT3 must be cognizant of the risks and benefits of therapy in addition to recognizing potential drug side effects. A nursing care plan was devised to identify nursing diagnoses and intervention related to patient and family education as well as recognition and treatment of the reported adverse effects.

Acute Disease↗
PubMed1989

Cytoskeletal rearrangement by oxidative stress.

The cytoskeleton is susceptible to oxidative stress and this occurs prior to membrane blebbing and cell lysis. Vimentin intermediary filaments in rheumatoid synoviocytes are more susceptible than in normal synoviocytes and this may have pathological significance. They are however no more susceptible to heat shock than other cell types.

Cells, Cultured↗
PubMed1988

Iron-sulfur centers involved in methanogenic electron transfer in Methanobacterium thermoautotrophicum (delta-H).

Utilizing a subcellular particulate preparation from Methanobacterium thermoautotrophicum (delta-H) which contains all detectable methanogenic electron transfer activity, we present the results of the effects of the anaerobic addition of oxidized factor F420 and of methyl coenzyme M plus ATP on the EPR signals from reduced iron-sulfur centers and a rapidly-relaxing radical species. Based on these results, we report the existence of a minimum of three iron-sulfur centers which are capable of donating electrons to these cofactors.

Anaerobiosis↗
PubMed1988

Lipid peroxidation is a consequence of elicitor activity.

Elicitor-active preparations from the fungal pathogen of bean Colletotrichum lindemuthianum stimulated the accumulation of products characteristic of lipid peroxidation in treated bean tissues. Bean suspension cells treated with crude and purified elicitors accumulated ;lipofuscin-like pigment' (LEP) and malondialdehyde. The accumulation of LFP after about 6 h of treatment coincided with the onset of visible browning and production of the bean phytoalexins kievitone, phaseollin, and phaseollinisoflavan. The induction of phytoalexins and accumulation of LFP were also triggered by treatments with generators of activated oxygen species, xanthine:xanthine oxidase and Fe:ethylenediaminedi-o-hydroxyphenylacetic acid. These data suggest that generation of active oxygen species may be involved in lipid peroxidation triggered by elicitors.

Journal Article↗
PubMed1987

The Effect of Extracellular Components from Colletotrichum lindemuthianum on Membrane Transport in Vesicles Isolated from Bean Hypocotyl.

Extracellular components released from mycelia of the alpha and beta races of the bean pathogen, Colletotrichum lindemuthianum, inhibited proton uptake in sealed vesicles prepared from bean hypocotyls. Differential sensitivity of ATP-driven proton transport to nitrate, vanadate, N,N'-dicyclohexylcarbodiimide, diethylstilbestrol, and oligomycin suggested the vesicles were enriched for tonoplast. Anion stimulation of proton transport, by enhancement of ATPase activity and dissipation of the membrane potential, was consistent with this conclusion. Although fungal components inhibited the formation of a pH gradient, the membrane potential was unaffected and the ATPase activity slightly stimulated. These data suggest that the fungal components produce an electroneutral proton exchange. Proton transport in Dark Red Kidney bean tonoplast vesicles was inhibited by mycelial preparations from the incompatible alpha race and compatible beta race. Elicitor activity, however, was greater in the alpha race fractions. Elicitor purified from alpha race culture filtrate did not inhibit proton transport in vesicles isolated from Dark Red Kidney bean. Consequently, elicitor activity need not be associated with an ability to impair tonoplast function.

Journal Article↗
PubMed1981

Stability of amino acids and the availability of acid in total parenteral nutrition solutions containing hydrochloric acid.

The stability of amino acids and the availability of acid from total parenteral nutrition (TPN) solutions containing hydrochloric acid were studied. Hydrochloric acid in the concentrations of 40 (TPN 1), 60 (TPN 2), and 100 (TPN 3) meq/liter was added to TPN solutions (4.25% amino acids, 25% dextrose monohydrate) containing various electrolytes (TPN control). Amino acid concentrations were determined from one sample of each solution using a Technicon Automatic Amino Acid Analyzer. Samples were analyzed 24 hours after mixing and compared with the TPN control at 24 hours. Tryptophan was assayed using a specific colorimetric assay at 0, 6, 24, and 48 hours. The concentrations of proline (76.2 of control) and histidine (85.7% of control) wee decreased in TPN 3. This phenomenon appeared to be dependent upon the concentration of hydrochloric acid in the TPN solution. There was no appreciable loss of any of the other amino acids in the test solution as compared with the control. Tryptophan levels fell in both the TPN control and the test solutions independent of the hydrochloric acid concentration. The pH of the solutions decreased with increasing concentrations of hydrochloric acid from 5.87 in the TPN control to 3.18 in TPN 3. The titratable acidity increased with increasing concentrations of hydrochloric acid (28.21 meq/liter in the TPN control to 115.54 meq/liter in TPN 3). Concentrations of some amino acids decreased in the presence of hydrochloric acid. Because of the short-time period in which these solutions will usually be infused (4-24 hours), this probably has a negligible effect on patients' nutritional therapy. The availability of acid from these solutions makes this combination useful in treating severe metabolic alkalosis.

Alkalosis↗
PubMed1981

Administrative audits of professional services: effective residency training experience.

The development of a structured method of providing administrative experience for hospital pharmacy residents, using internal audit techniques, is described. Residents were assigned topics to investigate in the administrative area of hospital pharmacy early during their two-year, academically affiliated residency. They were expected to review and evaluate the topic critically using internal audit techniques; written and oral reports were presented to the administrative staff. Residents were able to complete the audits while attending classes as part of their academic experience. As a result of performing the audits, residents have learned administrative skills in problem identification, assessed their personal competency by reviewing major components of contemporary practice, learned accepted standards of pharmacy practice, and developed skills in making improvements in conformity with quality assurance standards. This program has been incorporated as an integral part of the residency program.

Education, Pharmacy, Graduate↗
PubMed1981

Water permeation through polyvinyl chloride bags without overwrap.

Water loss by permeation from polyvinyl chloride i.v. containers (Viaflex, Travenol Laboratories) without an overwrap is reported. Viaflex bags without the overwrap containing 0.9% sodium chloride injection or 5% dextrose injection in 50-ml, 100-ml, 500-ml, and 1000-ml sizes were used. All sizes were stored at room temperatures (25 degrees C) and in a refrigerator (4-8 degrees C); the two smaller sizes were additionally in a frost-free freezer (-20 degrees C) and in a non-frost-free freezer (-20 degrees C). Ten bags of each type were stored for 84 days; each container weighed on days 0, 7, 14, 21, 28, 42, 56, 70, and 84 days. Based on the weight change exhibited during this initial period, the time required to lose 10% of the weight was predicted. The bags were stored for that period of time and then weighed. The weight loss exhibited zero-order kinetics. At room temperature, the 50-ml containers of both solutions lost greater than 10% during the 84-day period. During this time, the 100-ml containers of both solutions lost 9% of their weight. Weight loss in the larger sizes was less than 5% during the 84-day period at room temperature. Under the colder storage conditions, weight loss averaged much less than 5% for all sizes during the 84 days. During extended storage, weight loss continued at the same rate for the 100-ml container but was slower for the larger sizes. The Viaflex container without the overwrap may be stored in a refrigerator or freezer for up to 84 days without substantial loss of water by permeation.

Drug Packaging↗
PubMedDate not supplied

Characterization of disulfide crosslink formation of human vimentin at the dimer, tetramer, and intermediate filament levels.

We have investigated the structural interactions of individual molecules of human vimentin in the soluble state and in filaments. Oxidative crosslinking experiments were conducted with wild-type vimentin aimed at the single cysteine in the helical domain coil 2b, mutated cysteine-free vimentin, and derivatives engineered to carry cysteines in presumed d positions of the heptad amino acid repeats in coils 1a and 2b. We provide conclusive evidence that crosslinking of the cysteine 328 in wild-type vimentin, when in the filamentous or tetrameric forms, occurs outside of the coiled-coil dimer, i.e., between staggered dimer molecules. This occurs despite the close axial register of the dimers and contradicts previous deductions. The extent of crosslinking increases with temperature as well as with the concentration of the crosslinking reagent. We conclude therefore that the cysteines are not in an ideal position for crosslinking but that molecular motion is needed to enhance the reaction. The occurrence of collision complexes, which has been speculated in the literature, does not occur and cannot explain these results. Furthermore, using tailless vimentin with the corresponding mutations, we provide compelling evidence that in type III intermediate filament proteins exchange of individual chains between dimers occurs only if the proteins are incubated in urea at concentrations above 3 M. In 5 M urea, however, the exchange is completed within seconds. The same reaction occurs between human vimentin and mouse desmin at a comparable speed, indicating that both type III intermediate filament proteins have a high affinity for one another at the coiled-coil level.

Amino Acid Sequence↗
PubMedDate not supplied

Nature of spousal supportive behaviors that influence heart transplant patient compliance.

Heart transplant patient survival is dependent on strict adherence to a specific medical regimen including medication administration, infection control, diet, and exercise. The literature suggests that transplant patients are predisposed to noncompliance by virtue of the multiple factors involved in the regimen; it also suggests that spousal support may play a significant role in assisting patients to attain the regimen goals. The purpose of this descriptive study was to determine the nature of spousal behaviors influencing compliance. The method for this study involved designing an open-ended interview guide that elicited responses from married subjects, 6 to 18 months after transplantation, regarding their perceptions of spousal support. Responses were cross-classified according to a social support typology and the four regimen domains; frequency of responses was rank ordered. Spousal behaviors identified as supportive were predominantly informational (46.66%) and tangible (38.09%) in nature; only 15.23% were emotional. The data suggest a perceived need by most subjects to receive additional instruction, guidance, and feedback from the spouse; also, there is a tendency for patients to depend on their spouses for their material needs, physical assistance, and transportation until they are more capable. The results imply that because of patient personality and behavioral changes after surgery, it may be easier for spouses to avoid emotional aspects of support; communicating with patients on a more concrete level. Implications for nursing and other health care providers lie in identifying and cultivating those spousal behaviors that serve to motivate the patient toward compliance and optimal home health care maintenance.

Behavior↗