Biomedical subjects

K Green

Publications and source records attributed to K Green.

At least 199 records · Page 11Linked to original sources

PubMed1986

Intraocular pressure and aqueous humor dynamics in rabbit and primate with d- and 1-adrenergic compounds.

The effects of the d- and 1-isomers of epinephrine and norepinephrine have been determined on intraocular pressure (IOP) in conscious rabbits and rhesus monkeys, and on aqueous humor turnover rate (AHTR) in rabbits. Relatively specific beta-adrenergic antagonists (butoxamine and metoprolol) were used to attempt to modify the responses. The effects on IOP in both species are similar to those of racemic mixtures. The d- and 1-isomers of norepinephrine and epinephrine reduced IOP, and reduced AHTR in rabbits. The d- and 1-isomers of norepinephrine had little effect on IOP in monkeys while d- and 1-epinephrine increased IOP. Metoprolol, a beta 1-antagonist was more effective than butoxamine (beta 2-antagonist) at modifying the effect of the norepinephrine isomers in rabbits.

Animals↗

PubMed1986

Development of a measure of job satisfaction for dentists and dental auxiliaries.

This paper describes the development of a multidimensional, 38-item measure of job satisfaction appropriate for dentists, dental hygienists, and dental assistants. Items were grouped into the following 12 subscales: income, recognition, opportunity to develop professionally, time to develop professionally, responsibility, non-patient tasks, staff relations, quality of care, leisure time, fatigue, time pressure and general satisfaction. The measure was developed from a set of 45 items included in questionnaires administered to dentists and staff of 126 dental practices in Washington State, USA. Questionnaires were returned by 117, 121 and 106 dentists; 69, 80, and 82 hygienists; and 322, 329, and 320 assistants, respectively, in each of the 3 yr (1979, 1980, 1981). Factor analysis (principal components analysis with varimax rotation) plus categorization of items by a panel of professionals were used to initially group items into subscales. Contribution to internal consistency was the final criterion for an item's inclusion in a subscale. Internal consistency reliability of subscales ranged from 0.68 to 0.95. Statistically significant relationships were found between individual job satisfaction subscales and intent to change job for hygienists and assistants.

Dental Assistants↗

PubMed1986

Rabbit corneal endothelial physiologic and morphologic characteristics following storage in MK medium and K-Sol.

Rabbit corneas were stored for 3, 7, 10 or 14 days in MK medium or K-Sol. Corneas were thinner immediately following removal from K-Sol than following removal from MK medium at all time periods studied. Following 3 days of storage, corneas stored in both solutions showed similar temperature reversal characteristics. Corneas stored for 7 and 10 days in MK medium also temperature reversed, whereas those stored in K-Sol did not. Corneas stored for 14 days in both solutions swelled following mounting in the specular microscope. Endothelial cell morphology was similar following storage in MK medium and K-Sol at all time periods studied. It is postulated that a persistant osmotic gradient is present across the endothelium following storage in K-Sol. This osmotic gradient occurs because of retention of chondroitin sulphate in the corneal stroma thereby preventing early temperature reversal.

Animals↗

PubMed1986

Effect of honan intraocular pressure reducer on ocular and optic nerve blood flow in phakic rabbit eyes.

The Honan Intraocular Pressure Reducer (HIPR) was applied to rabbit eyes for 30 min at pressure settings of 0, 30, 50, or 100 mmHg. Ocular blood flow was measured using (85Sr) radioactively labelled 15 micron microspheres either with the HIPR applied to the eye or 15 min after removal. Intraocular pressure was measured before applying the HIPR, immediately after removal, or 15 min after removal. At all pressure settings, the HIPR significantly lowered the IOP (P less than or equal to 0.05) both immediately and 15 min after removal. At all pressure settings, except 0 mmHg, blood flow was significantly (P less than or equal to 0.05) both immediately and 15 min after removal. At all pressure settings, except 0 mmHg, blood flow was significantly (P less than or equal to 0.05) lower with the HIPR applied compared to 15 min after removal.

Animals↗

PubMed1986

Effect of digital massage on intraocular pressure and ocular and optic nerve blood flow.

The effect of digital massage on intraocular pressure and ocular and optic nerve blood flow was studied in anaesthetized rabbits. Digital massage was performed for 15 min, with pressure release for 15 seconds after each 45 seconds of massage. Blood flow was measured in the iris, ciliary processes, choroid, retina, and optic nerve using (85Sr)-labelled microspheres. Blood flow was determined during massage, 2 min after, or 15 min after massage. Intraocular pressure was measured before, immediately after, and in one group, 15 min after massage. Immediately after digital massage, intraocular pressure was significantly lower, but 15 min after it was not significantly reduced. At both 2 min and 15 min after digital massage, compared to during massage, blood flow was significantly higher in all tissues studied.

Animals↗

PubMed1986

Conservation of the fourth gene among rotaviruses recovered from asymptomatic newborn infants and its possible role in attenuation.

RNA-RNA hybridization was performed to assess the extent of genetic relatedness among human rotaviruses isolated from children with gastroenteritis and from asymptomatic newborn infants. 32P-labeled single-stranded RNAs produced by in vitro transcription from viral cores of the different strains tested were used as probes in two different hybridization assays: undenatured genomic RNAs were resolved by polyacrylamide gel electrophoresis, denatured in situ, electrophoretically transferred to diazobenzyloxymethyl-paper (Northern blots), and then hybridized to the probes under two different conditions of stringency; and denatured genomic double-stranded RNAs were hybridized to the probes in solution and the hybrids which formed were identified by polyacrylamide gel electrophoresis. When analyzed by Northern blot hybridization at a low level of stringency, all genes from the strains tested cross-hybridized, providing evidence for some sequence homology in each of the corresponding genes. However, when hybridization stringency was increased, a difference in gene 4 sequence was detected between strains recovered from asymptomatic newborn infants ("nursery strains") and strains recovered from infants and young children with diarrhea. Although the nursery strains exhibited serotypic diversity (i.e., each of the four strains tested belonged to a different serotype), the fourth gene appeared to be highly conserved. Similarly, each of the virulent strains tested belonged to a different serotype; nonetheless, there was significant conservation of sequence among the fourth genes of three of these viruses. Significantly, the conserved fourth genes of the nursery strains were distinct from the fourth gene of each of the virulent viruses. These results were confirmed and extended during experiments in which the RNA-RNA hybridization was carried out in solution and the resulting hybrids were analyzed by polyacrylamide gel electrophoresis. Under these conditions, the fourth genes of the nursery strains were closely related to each other but not to the fourth genes of the virulent viruses. Full-length hybrids did not form between the fourth genes from the nursery strains and the corresponding genes from the strains recovered from symptomatic infants and young children.

Diarrhea, Infantile↗

PubMed1986

In vivo production of prostacyclin and thromboxane in patients with acute myocardial infarction.

The in vivo production of prostacyclin and thromboxane was monitored by measuring their major urinary metabolites 2,3-dinor-thromboxane B2 and 2,3-dinor-6-keto-prostaglandin F1 alpha in ten patients with acute myocardial infarction, five on standard treatment and five receiving prostacyclin infusion. During acute myocardial infarction excretion of 2,3-dinor-thromboxane B2 and 2,3-dinor-6-keto-prostaglandin F1 alpha, measured by a gas chromatography-mass spectrometry method with deuterated internal standards, was significantly increased. This indicates that thromboxane and prostacyclin synthesis are increased during the development of acute myocardial infarction. The excretion data for 2,3-dinor-thromboxane B2 showed that after administration of aspirin there was less pronounced and more variable inhibition than expected. Prostacyclin infusion did not markedly affect the excretion of the thromboxane metabolite.

6-Ketoprostaglandin F1 alpha↗

PubMed1986

Further studies on the effect of retrobulbar epinephrine injection on ocular and optic nerve blood flow.

The effect of retrobulbar epinephrine administration on ocular and optic nerve blood flow was studied in phakic rabbit eyes using a radioactive microsphere (85Sr) technique. Blood flow measurements were performed either 5 minutes or 30 minutes after retrobulbar injection of 10 microliter of a 2% (base) epinephrine bitartrate solution to the right eye of each rabbit. Blood flow was determined for the iris, scraped ciliary processes, choroid, retina, and optic nerve. Five minutes after retrobulbar injection, there was no statistically significant (P greater than 0.05) difference in epinephrine-treated eyes compared to contralateral control eyes that received 10 microliters of retrobulbar saline. Thirty minutes after injection, eyes receiving retrobulbar epinephrine had a statistically significant (P less than 0.05) fall in blood flow to the iris and scraped ciliary processes, but not to the choroid, retina, or optic nerve.

Animals↗

PubMed1986

Effect of dextran-bound acetazolamide on rabbit corneal endothelial ion fluxes.

The effects of a carbonic anhydrase inhibitor, acetazolamide, bound to a 72,000 dalton dextran (DBI) on bicarbonate and sodium fluxes across the isolated rabbit corneal endothelium have been examined. When DBI was present on the aqueous-facing endothelial surface, there was a marked inhibition of both the stromal to endothelial unidirectional and net flux of bicarbonate. This suggests that the exit of bicarbonate from the cell into the aqueous-facing solution is influenced by the enzyme carbonic anhydrase. No change was found in sodium fluxes under these same incubation conditions. When DBI was present on the stromal-facing surface of the endothelium, no changes were found in unidirectional or net bicarbonate fluxes; the sodium flux from stroma to endothelium was increased, however, with no change in net flux. This data implies that the link between sodium and bicarbonate movement across the endothelium is not a direct coupling between the transport of the two ions in the form of a symport (Na+:HCO3-) at the apical cell border.

Acetazolamide↗

PubMed1986

The effect of retrobulbar lidocaine injection on ocular and optic nerve blood flow.

The effect of retrobulbar lidocaine administration on ocular and optic nerve blood flow was studied in phakic rabbit eyes using a radioactive microsphere (85Sr) technique. Blood flow measurements were performed 15 minutes after retrobulbar injection of 40 mg of lidocaine in ethanol to the right eye of each rabbit. Blood flow measurements were determined for the iris, scraped ciliary processes, choroid, retina, and optic nerve. There was no statistically significant (P less than 0.05) difference in lidocaine treated eyes compared to contralateral control eyes. An identical volume of retrobulbar ethanol alone had no effect on regional blood flow.

Animals↗

PubMed1986

Effects of water-soluble marihuana-derived material (MDM) on the rabbit ciliary body: light and electron microscopy.

The response of the ciliary processes of the rabbit eye to water-soluble marihuana-derived material (MDM) has been examined with light and electron microscopy. Following intravenous injection of MDM, the processes undergo considerable swelling within 1 hour followed by thrombus formation in the capillaries and extravasation of red cells. Later phases include the formation of cysts between the non-pigmented and pigmented cell layers of the ciliary epithelium. The ciliary process edema coincides with the initial hypertensive phase seen after intravenous MDM, while the hematogenous response coincides with the fall in intraocular pressure. Following intravitreal injection of MDM, a similar pattern of structural changes occurs that accompanies a fall in intraocular pressure that lasts for several days; because the physiological response occurs over a longer time course (14-20 hours) relative to intravenous administration where the intraocular pressure changes occur rapidly, the ciliary process swelling phase does not result in an increase in intraocular pressure. The physiologic changes in the eye caused by MDM appear to be related to the induction of a general inflammatory response in the ciliary processes, with a primary effect on the vascular system.

Animals↗

PubMed1986

The interrelationship between intraocular pressure and Honan Intraocular Pressure Reducer pressure.

The relationship between the pressure applied to the enucleated human eye using the Honan Intraocular Pressure Reducer (HIPR) and the peak intraocular pressure as a function of initial intraocular pressure has been examined. The peak intraocular pressure is linearly related to the applied HIPR pressure whether the latter is 30, 50, or 75 mm Hg. The slopes relating peak intraocular pressure to initial intraocular pressure at different HIPR settings are parallel. Use of the HIPR at settings greater than 30 mm Hg and an initial IOP of greater than 30 mm Hg could compromise ocular vascular perfusion.

Humans↗

PubMed1986

Distribution of a steroid antagonist in the eye following topical administration.

The distribution of a steroid antagonist, RU486, that is known to reduce rabbit intraocular pressure has been examined in the eye. On an equal tissue weight basis, the corneal epithelium is the site of maximal absorption followed by conjunctival tissues (bulbar and palpebral) and the rest of the cornea. Aqueous humor concentrations of drug vary between 5 X 10(-6) and 5 X 10(-8) at 1 and 24 hours, respectively: these concentrations have been shown by others to inhibit dexamethasone binding to rat thymocytes, and are sufficient to act as an antagonist at steroid receptors in the eye. Multiple drop administration for 10 days (3 drops per day) revealed no accumulation in the treated eye, but did show the presence of drug in the untreated contralateral eye that could explain the contralateral pharmacological effect seen on intraocular pressure after several days of treatment.

Administration, Topical↗

PubMed1986

BSS and BSS-plus: effect on corneal endothelial ionic and non-ionic fluxes.

Rabbit corneas were mounted in water jacketed chambers and the endothelial surface perfused with either BSS (Balanced Salt Solution) or BSS-Plus for 3 hr. Unidirectional and net fluxes of sodium were similar in both groups of corneas. Bicarbonate fluxes in BSS-Plus were statistically similar to those in Krebs-Ringer solution. Bicarbonate fluxes could not be determined with BSS because the solution does not contain bicarbonate. In addition, there was no statistically significant alteration of inulin or dextran permeability when comparing perfusion with BSS and BSS-Plus. From this study it appears that BSS and BSS-Plus are comparable in their ability to maintain corneal endothelial physiologic function during in-vitro perfusion. This is in contrast to previous work which showed that BSS-Plus induced less endothelial morphologic change than BSS. It is concluded that morphologic alterations may be more sensitive parameters of endothelial stress than are fluxes and permeabilities.

Acetates↗

PubMed1986

Effect of ambient pH on corneal endothelial sodium fluxes.

Sodium fluxes across the isolated rabbit corneal endothelium were measured as a function of ambient pH and bicarbonate concentrations. At pH 7, the net sodium flux (J endo str net) was effectively obliterated at all bicarbonate concentrations, relative to controls at pH 7.5. At pH 8, the net sodium flux was obliterated at 5 mM bicarbonate, was unchanged at 25 mM bicarbonate, and was enhanced at 40 mM bicarbonate, relative to controls at pH 7.5. The decrease in net sodium flux under these conditions relative to previously demonstrated maintenance of bicarbonate fluxes under almost identical conditions suggest that sodium and bicarbonate transverse the endothelium by different routes. In addition, changes in unidirectional fluxes, when ambient pH is decreased from 7.5 to 7, are not equal, illustrating that the fluxes probably occur via different pathways. A complex interrelationship exists between sodium, bicarbonate, and proton movement.

Animals↗

PubMed1985

Effect of applying the Honan intraocular pressure reducer before cataract surgery.

We studied 48 patients undergoing cataract extraction with local anesthesia. In 41 patients, after administering the retrobulbar injection, we applied the Honan intraocular pressure reducer for seven to ten minutes at a pressure setting of 30 mm Hg. Of these 41 patients, 13 received 3-ml injections, 14 received 4-ml injections, and 14 received 5-ml injections. No differences in intraocular pressure related to the quantity of retrobulbar injection were noted. After retrobulbar injection, the mean intraocular pressure for the study population as a whole increased 4.4 mm Hg; after application of the Honan device, it decreased 6.2 mm Hg. In a control group of seven patients, who received 4-ml retrobulbar injections but no applications of the Honan device, mean intraocular pressure increased 6.1 mm Hg immediately after retrobulbar injection and decreased only 0.7 mm Hg after seven to ten minutes.

Bupivacaine↗

PubMed1985

In vivo production of thromboxane in acute human myocardial infarction: a preliminary study.

Using a specific quantitative method based on gas chromatography-mass spectrometry the urinary excretion of 2,3-dinor-TxB2 was measured in five patients with acute myocardial infarction shortly after the onset of symptoms. The urinary excretion of 2,3-dinor-TxB2 was markedly higher than seen in normals in three of the five patients. This increased excretion of 2,3-dinor-TxB2 during and after the development of myocardial necrosis indicates an involvement of thromboxane A2 in the pathogenesis of at least some cases of acute myocardial infarction.

Aged↗

PubMed1985

Corneal endothelium following immersion of eyes in water.

Eye banks are occasionally asked to retrieve corneal tissue from drowning victims. The ambient water surrounding the eyes before recovery of the victim has chemical, pH, and osmotic characteristics different from those of aqueous humor, thereby possibly making corneas recovered from these eyes unsuitable for transplantation. Corneal endothelial cell function and ultrastructure were maintained following soaking of rabbit eyes for three hours in either seawater, fresh lake water, or chlorinated swimming-pool water at 25 degrees C. The data suggest that physiological and ultrastructural integrity of the corneal endothelium is maintained under these conditions, and that if other, generally accepted criteria of donor suitability are met, such corneas are probably suitable for transplantation.

Animals↗