Search PubMed⌕ Search

Biomedical subjects

K Fisher

Publications and source records attributed to K Fisher.

At least 37 records · Page 2Linked to original sources
PubMed2000

Evaluation of two new soft contact lenses for correction of presbyopia: the Focus Progressives multifocal and the Acuvue Bifocal.

The clinical performance of Focus Progressives multifocal contact lenses and Acuvue Bifocal contact lenses was evaluated in a group of 42 presbyopes, with equal numbers of individuals having low, medium, and high spectacle add requirements. Following visual performance assessment with an optimal sphero-cylinder spectacle refractive correction, each individual wore each of the two types of contact lenses in successive random order. Each type of lens was used in a daily-wear mode for a period of 7 to 12 days, with follow-up and/or refitting visits occurring after 2 to 5 days, and again after 4 to 7 days of attempted wear. Testing for all three forms of refractive correction encompassed Snellen acuities at distance and near, Bailey-Lovie acuities under high and/or low ambient illumination conditions at near, intermediate, and far viewing distances, stereoacuity, a timed visuomotor task (needle threading), apparent glare/flare, and the nearwork range of subjectively clear binocular vision. The contact lenses also were evaluated for handling, comfort, distance and near ghosting, subjective visual quality, acceptability for common tasks (e.g., using a phone directory), and personal preferences.As might be expected, distance and near acuity, stereoacuity, and visuomotor task performance were somewhat better with sphero-cylinder spectacle correction than with either of the two types of contact lenses. However, several performance differences between the multifocal and bifocal lenses were noted. The Focus Progressives lenses provided significantly better distance acuity under both high and low illumination conditions, and received significantly higher ratings for visual quality (overall and at distance), comfort, and handling. The Focus Progressives lenses were preferred 5:1 over the Acuvue Bifocal lenses. No differences existed between the lenses with respect to near visual acuities, the perceived quality of the near vision, the nearpoint binocular range, stereoacuity, or the acceptability of vision for common nearwork tasks. The results suggest that although both types of lenses afford presbyopes a viable alternative to spectacles, the Focus Progressives lens is superior in many ways to the Acuvue Bifocal lens.

Journal Article↗
PubMed2000

Evidence that DHPG-induced nociception depends on glutamate release from primary afferent C-fibres.

We examined whether enhanced glutamate release contributes to the expression of persistent spontaneous nociceptive behaviours (SNBs) in rats induced by intrathecal (i.t.) administration of the selective group I mGluR agonist, (RS)-3,5-dihydroxyphenylglycine ((RS)-DHPG). Pretreatment with drugs that have been shown to inhibit glutamate release, including a group II metabotropic glutamate receptor (mGluR) agonist (2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate ((2R,4R)-APDC), a group III mGluR agonist L-2-amino-4-phosphonobutyrate (L-AP4), or the use-dependent sodium channel blockers 3,5-diamino-6-(2,3-diclorophenyl)-1,2,4-triazine (lamotrigine) and 2-amino-6-trifluoromethoxybenzothiazole (riluzole), produced dose-dependent reductions in (RS)-DHPG-induced SNBs. We have also shown that incubation of rat lumbar spinal cord slices with (RS)-DHPG potentiates 4-aminopyridine-evoked (4-AP) release of glutamate. Furthermore, we found that destruction of unmyelinated primary afferent C-fibres by neonatal capsaicin treatment significantly reduced (RS)-DHPG-induced SNBs in adult rats. Together, these results suggest that (RS)-DHPG-induced nociception is dependent on spinal glutamate release, probably from primary afferent C-fibres.

4-Aminopyridine↗
PubMed2000

Azotobacter vinelandii nitrogenases containing altered MoFe proteins with substitutions in the FeMo-cofactor environment: effects on the catalyzed reduction of acetylene and ethylene.

Altered MoFe proteins of Azotobacter vinelandii Mo-nitrogenase, with amino acid substitutions in the FeMo-cofactor environment, were used to probe interactions among C(2)H(2), C(2)H(4), CO, and H(2). The altered MoFe proteins used were the alpha-195(Asn) or alpha-195(Gln) MoFe proteins, which have either asparagine or glutamine substituting for alpha-histidine-195, and the alpha-191(Lys) MoFe protein, which has lysine substituting for alpha-glutamine-191. On the basis of K(m) determinations, C(2)H(2) was a particularly poor substrate for the nitrogenase containing the alpha-191(Lys) MoFe protein. Using C(2)D(2), a correlation was shown between the stereospecificity of proton addition to give the products, cis- and trans-C(2)D(2)H(2), and the propensity of nitrogenase to produce ethane. The most extensive loss of stereospecificity occurred with nitrogenases containing either the alpha-195(Asn) or the alpha-191(Lys) MoFe proteins, which also exhibited the highest rate of ethane production from C(2)H(2). These data are consistent with the presence of a common ethylenic intermediate on the enzyme, which is responsible for both ethane production and loss of proton-addition stereochemistry. C(2)H(4) was not a substrate of the nitrogenase with the alpha-191(Lys) MoFe protein and was a poor substrate of the nitrogenases incorporating either the wild-type or the alpha-195(Gln) MoFe protein, both of which had a low V(max) and high K(m) (120 kPa). Ethylene was a somewhat better substrate for the nitrogenase with the alpha-195(Asn) MoFe protein, which exhibited a K(m) of 48 kPa and a specific activity for C(2)H(6) formation from C(2)H(4) 10-fold higher than the others. Neither the wild-type nitrogenase nor the nitrogenase containing the alpha-195(Asn) MoFe protein produced cis-C(2)D(2)H(2) when turned over under trans-C(2)D(2)H(2). These results suggest that the C(2)H(4)-reduction site is affected by substitution at residue alpha-195, although whether the effect is related to the substrate-reduction site directly or is mediated through disturbance of the delivery of electrons/protons is unclear. Ethylene inhibited total electron flux, without uncoupling MgATP hydrolysis from electron transfer, to a similar extent for all four A. vinelandii nitrogenases. This observation indicates that this C(2)H(4) flux-inhibition site is remote from the C(2)H(4)-reduction site. Added CO eliminated C(2)H(4) reduction but did not fully relieve its electron-flux inhibition with all four A. vinelandii nitrogenases, supporting the suggestion that electron-flux inhibition by C(2)H(4) is not directly connected to C(2)H(4) reduction. Thus, C(2)H(4) has two binding sites, and the presence of CO affects only the site at which it binds as a substrate. When C(2)H(2) was added, it also eliminated C(2)H(6) production from C(2)H(4) and also did not relieve electron-flux inhibition fully. Thus, C(2)H(2) and C(2)H(4) are likely reduced at the same site on the MoFe protein. Two schemes are presented to integrate the results of the interactions of C(2)H(2) and C(2)H(4) with the MoFe proteins.

Acetylene↗
PubMed2000

The involvement of dopamine in nociception: the role of D(1) and D(2) receptors in the dorsolateral striatum.

Determination of the neuroanatomical and neurochemical factors that contribute to nociception is an essential element in the study and treatment of pain. Several lines of evidence have implicated nuclei and neurotransmitters within the basal ganglia in nociception. For example, previous studies have shown that dopamine receptors in the striatum are involved in acute nociception, however, it remains to be determined if dopamine receptors in the dorsolateral striatum are involved in persistent nociception. The purpose of the present study was therefore to determine whether activation or antagonism of dopamine receptors in the dorsolateral striatum influences the nociceptive responses of rats in the formalin test, a model of persistent pain. It was found that micro-injection of the non-selective dopamine antagonist haloperidol into the dorsolateral striatum increases formalin-induced nociception whereas injection of the non-selective dopamine agonist apomorphine reduces formalin-induced nociception. Injection of the D(1) antagonist SCH23390 or the D(1) agonist SKF38393 does not affect formalin-induced nociception. In contrast, injection of the D(2) antagonist eticlopride enhances formalin-induced nociception, whereas injection of the D(2) agonist quinpirole reduces formalin-induced nociception. These results provide additional evidence that dopamine receptors in the striatum are involved in nociception. Furthermore, this study strongly suggests that D(2), but not D(1), dopamine receptors in the dorsolateral striatum are involved in modulation of persistent nociception.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed2000

Enhanced type I immune response to a hepatitis B DNA vaccine by formulation with calcium- or aluminum phosphate.

DNA vaccines induce protective humoral and cell-mediated immune responses in several animal models. When compared with conventional vaccines, however, DNA vaccines often induce lower antibody titers. We have now found that formulation of a DNA vaccine encoding hepatitis B surface antigen with calcium- or aluminum phosphate adjuvants can increase antibody titers by 10-100-fold and decrease the immunogenic dose of DNA by 10-fold. Furthermore, boosting an HBs protein-primed response with the adjuvanted DNA vaccine resulted in a dramatic increase in the HBs-specific IgG2a response reflecting a shift towards a TH1 response. The mechanism by which aluminum phosphate exerts its adjuvant effect is not through increased expression of HBsAg in vivo; rather, the adjuvant appears to increase the number and affinity of HBs peptide antigen-specific IFN-gamma and IL-2 secreting T cells.

Adjuvants, Immunologic↗
PubMed2000

Targeting the N-methyl-D-aspartate receptor for chronic pain management. Preclinical animal studies, recent clinical experience and future research directions.

A 1967-1999 MEDLINE search of published reports evaluating the role of the glutamate N-methyl-D-aspartate (NMDA) receptor in pain identified 378 animal studies and 132 human studies. There is convincing evidence in these studies that the NMDA receptor mediates prolonged nociceptive behaviors in animal models and various chronic pain symptoms in the clinical population. Administration of older compounds, such as ketamine, dextromethorphan, and amantadine, which are now known to act as NMDA receptor antagonists, have recently been shown to alleviate chronic pain. For years, the pharmaceutical industry has been attempting to produce novel compounds that modulate NMDA receptor activity; however, the adverse effects associated with this class of drugs have prevented their widespread clinical use. Collaborative studies between basic researchers, clinical scientists, and clinicians are needed to delineate characteristics of NMDA receptor antagonism that predict optimal analgesic activity and an acceptable toxicity profile in patients with chronic pain.

Animals↗
PubMed2000

Violence and its injury consequences in American movies: a public health perspective.

OBJECTIVES: To evaluate the seriousness and frequency of violence and the degree of associated injury depicted in the 100 top-grossing American films of 1994. METHODS: Each scene in each film was examined for the presentation of violent actions on persons and coded by a systematic context-sensitive analytic scheme. Specific degrees of violence and indices of injury severity were abstracted. Only actually depicted, not implied, actions were coded, although both explicit and implied consequences were examined. RESULTS: The median number of violent actions per film was 16 (range, 0-110). Intentional violence outnumbered unintentional violence by a factor of 10. Almost 90% of violent actions showed no consequences to the recipient's body, although more than 80% of the violent actions were executed with lethal or moderate force. Fewer than 1% of violent actions were accompanied by injuries that were then medically attended. CONCLUSIONS: Violent force in American films of 1994 was overwhelmingly intentional and in 4 of 5 cases was executed at levels likely to cause significant bodily injury. Not only action films but movies of all genres contained scenes in which the intensity of the action was not matched by correspondingly severe injury consequences. Many American films, regardless of genre, tend to minimize the consequences of violence to human beings.

Humans↗
PubMed2000

Violence and its injury consequences in American movies: a public health perspective.

OBJECTIVES: The purpose of this study was to evaluate the seriousness and frequency of violence and the degree of associated injury depicted in the 100 top grossing American films of 1994. METHODS: Each scene in each film was examined for the presentation of violent actions upon persons and coded by means of a systematic context sensitive analytic scheme. Specific degrees of violence and indices of injury severity were abstracted. Only actually depicted, not implied, actions were coded, although both explicit and implied consequences were examined. RESULTS: The median number of violent actions per film was 16, with a range from 1 to 110. Intentional violence outnumbered unintentional violence by a factor of 10. Almost 90% of violent actions showed no consequences to the recipient's body, although more than 80% of the violent actions were executed with lethal or moderate force. Fewer than 1% of violent actions were accompanied by injuries that were then medically attended. CONCLUSIONS: Violent force in American films of 1994 was overwhelmingly intentional and in four of five cases was executed at levels likely to cause significant bodily injury. Not only action films but movies of all genres contained scenes in which the intensity of the action was not matched by correspondingly severe injury consequences. Many American films, regardless of genre, tend to minimize the consequences of violence to human beings.

Americas↗
PubMed2000

Genetic sexing strains of mediterranean fruit fly (Diptera: Tephritidae): quality in mass-reared temperature-sensitive lethal strains treated at high temperatures.

The high-temperature treatment of eggs of mass-reared tsl genetic sexing strains in Mediterranean fruit fly, Ceratitis capitata (Wiedemann), during late embryogenesis (the low-high protocol) conserves more male flies than treatment during early embryogenesis. A tsl strain, AUSTRIA 6-97, was constructed to follow the fate of aneuploid individuals during male-only production. Aneuploid individuals are produced following segregation in the translocation heterozygous males, and they can survive to the pupal stage where they compromise quality because they do not eclose as adults. Hatching, emergence, and male fly production were quantified and the heat-treatment protocol was characterized. The low-high egg treatment conserves the number of euploid-balanced males, and there is a very low survival of aneuploid males. After heat treatment of eggs, at least 95% of the male pupae were euploid compared with only 71% from untreated eggs. The quality of euploid male pupae was diminished with successive daily collections, an effect previously attributed to aneuploid survivors. Reduced yield of euploid males from early heat treatments was the result of an emergence effect, in addition to a maternal effect. A third detrimental effect of heat was found, occurring after hatching and before pupation, that reduces the survivorship of euploid males. The low-high treatment protocol yielded more males, with a higher accuracy than other heat treatments. However, although it avoids both the maternal and emergence effects, the production of euploid males was 30% less than the potential production, implying that the low-high heat protocol for killing female embryos in tsl genetic sexing strains can be fine-tuned.

Animals↗
PubMed2000

Scoliosis associated with typical Mayer-Rokitansky-Küster-Hauser syndrome.

Disorders that cause congenital scoliosis include Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome. We present the case of a 46-year-old karyotypical (XX) woman with müllerian agenesis (MRKH type A, typical form), a rudimentary bicornate uterus, a blind vaginal pouch, and adenocarcinoma of both ovaries with subsequent bilateral salpingo-oophorectomy. She also had scoliosis of the thoracic and lumbar spine, an association thus far seen only among patients with type B (atypical) MRKH. We describe typical and atypical forms of MRKH and emphasize how these various anomalies associated with müllerian agenesis have affected the classification of the syndrome. We also outline possible embryologic etiologies of müllerian agenesis.

Abnormalities, Multiple↗
PubMed1999

A lung nematode in Canadian Arctic muskoxen. Standard radiographic and computed tomographic imaging.

Medical imaging was used before death to follow the development of U. pallikuukensis infection in muskoxen and postmortem to investigate the distribution and characteristics of parasite-associated pulmonary cysts. In two experimentally infected animals, lesions were not visible radiographically until days 178 and 191 PI, 3 months after the parasites became patent. Serial radiographs taken throughout the period of patency of one animal showed an initial increase in lesion size by day 415 PI, but by day 789 PI, lesions had stabilized or decreased in size. Although all lesions detected postmortem were not visible radiographically during life, the radiographs did provide an indication of the relative severity of infection. In contrast to other parasitic pneumonias, there was no evidence of pulmonary disease outside of the discrete parasitic cysts. Radiographs of lungs postmortem proved to be an effective tool for locating parasitic cysts in a lightly infected muskox and demonstrated a bronchovascular cyst distribution. Postmortem CT provided a more rapid and detailed assessment of the number, size, and distribution of cysts in the lungs of one muskox.

Animals↗
PubMed1999

Analgesic effect of oral ketamine in chronic neuropathic pain of spinal origin: a case report.

Ketamine is an injectable anesthetic induction agent that has been reported to have analgesic activity in pain from a variety of mechanisms, but predominantly in neuralgic and dysesthetic neuropathic pain. In this case report we illustrate the effectiveness of ketamine in a patient with neuropathic pain resulting from cauda equina trauma. Among the issues addressed are the role of pretreatment with haloperidol to prevent ketamine-induced psychomimetic effects, the potential for fewer side effects and a need for lower doses when ketamine is administered orally, and the need for further study regarding appropriate monitoring parameters during the titration phase. Oral ketamine can be effective in treatment refractory chronic neuropathic pain of spinal origin.

Administration, Oral↗
PubMed1999

Health care change: challenge for nurse administrators.

Nursing administrators facing reorganization understand the difficulties and resistance that accompany organizational change. This article discusses resilience, a critical character trait for successfully managing change. Understanding the change process can assist those charged with the challenge of leading organizational change to manage the journey more effectively.

Attitude of Health Personnel↗
PubMed1999

Culturalizing health care for a culturally diverse population: the Amish.

Advanced practice nurses (APNs) are often the major source of primary care for culturally diverse groups. Working with patients who have values that differ from the mainstream culture can make delivery of health care complex and challenging. The purpose of this qualitative study was to use grounded theory methods to explore the process by which APNs develop and maintain therapeutic relationships with a culturally unique group, the Amish. Nine APNs who practiced primarily with Amish patients were interviewed about their strategies to promote therapeutic relationships. The process of culturalizing health care emerged as the strategy used by the APNs. Specific themes were learning the culture, developing a relationship, individualizing care, being comfortable with abilities, and working two systems. Rather than expecting patients to conform to the mainstream cultural beliefs and practices, APN informants used a variety of methods that allowed Amish patients to blend self-care practices with conventional (i.e., English care).

Attitude to Health↗
PubMed1998

Effects on substrate reduction of substitution of histidine-195 by glutamine in the alpha-subunit of the MoFe protein of Azotobacter vinelandii nitrogenase.

Studies of the substrate-reducing capabilities of an altered nitrogenase MoFe protein (alpha-195(Gln) instead of alpha-195(His)) from a mutant of Azotobacter vinelandii show, contrary to an earlier report [Kim, C.-H., Newton, W. E., and Dean, D. R. (1995) Biochemistry 34, 2798-2808], that the alpha-195(Gln) MoFe protein can reduce N2 to NH3 but at a rate that is <2% of that of the wild type. The extent of effective binding of N2 by this altered MoFe protein, as monitored by the inhibition of H2 evolution, is markedly increased as temperature is lowered but virtually eliminated at 45 degreesC. This inhibition of H2 evolution results in an increase in the ATP:2e- ratio, i.e., the number of molecules of MgATP hydrolyzed for each electron pair transferred to substrate, from ca. 5 (the wild-type level) at 45 degreesC to nearly 25 at 13 degreesC. Like wild-type nitrogenase, the N2 inhibition of H2 evolution reaches a maximum at an Fe protein:MoFe protein molar ratio of ca. 2.5, suggesting that a highly reduced enzyme may not be necessary for N2 binding. N2 binding to the alpha-195(Gln) MoFe protein retains a hallmark of the wild type by producing HD under a mixed N2/D2 atmosphere. The rate of HD production and the fraction of total electron flow allocated to HD are similar to those for wild-type nitrogenase under the same conditions. However, the electrons forming HD do not come from those normally producing NH3 (as occurs in the wild type) but are equivalent to those whose evolution as H2 had been inhibited by N2. N2 also inhibits C2H2 reduction catalyzed by the alpha-195(Gln) nitrogenase. This inhibition is relieved by added H2, resulting in a lowering of the elevated ATP:2e- ratio to that found under Ar. With solutions of NaCN, which contain both the substrate, HCN, and the inhibitor, CN-, reduction of HCN is not impaired with the alpha-195(Gln) nitrogenase, but the inhibition by CN- of total electron flow to substrate, which is observed with the wild-type MoFe protein, is completely absent. Unlike that of the catalyzed reduction of H+, HCN, or C2H2, the extent of azide reduction to either N2 or N2H4 is markedly decreased (to 5-7% of that of the wild type) with the alpha-195(Gln) nitrogenase. Azide, like N2, inhibits H2 evolution and increases the ATP:2e- ratio. Both effects are freely reversible and abolished by CO. Added D2 does not relieve either effect, implying that N2 produced from N3- is not the inhibitory species. The correlation between the extremely low rates of reduction for both N2 and azide by the alpha-195(Gln) nitrogenase and their common ability to inhibit H2 evolution suggests that alpha-histidine-195 may be an important proton conductor to the FeMo cofactor center and specifically required for reduction of these two substrates.

Adenosine Triphosphate↗
PubMed1998

Hyperalgesia and allodynia induced by intrathecal (RS)-dihydroxyphenylglycine in rats.

To investigate the role of Group I mGluRs in allodynia and hyperalgesia, we examined the behavioural responses of rats to noxious and non-noxious mechanical and thermal stimuli following intrathecal (i.t.) treatment (25 nmol) with the selective mGluR1/5 agonist, (RS)-dihydroxyphenylglycine ((RS)-DHPG). (RS)-DHPG administration produced a persistent decrease in response latency on a 48 degrees C hotplate, a reduction in the 50% response threshold to von Frey hairs, and an increase in responses to a tail pinch. These data suggest that activation of spinal mGluR1/5 receptors plays a role in the development of persistent allodynia and hyperalgesia associated with tissue or nerve injury.

Animals↗