Biomedical subjects

K Green

Publications and source records attributed to K Green.

At least 181 records · Page 10Linked to original sources

PubMed1988

Sequence of the fourth gene of human rotaviruses recovered from asymptomatic or symptomatic infections.

The complete nucleotide sequence of the fourth gene of symptomatic (Wa, DS-1, P, and VA70) and asymptomatic (M37, 1076, McN13, and ST3) rotaviruses of serotype 1, 2, 3, or 4 was determined by the dideoxy chain termination method. In each strain, the fourth gene, which encodes the outer capsid protein VP3, is 2,359 base pairs in length and has 5'- and 3'-noncoding regions of 9 and 25 nucleotides, respectively. The gene has a single long open reading frame of 2,325 base pairs that is capable of coding for a protein of 775 amino acids. A total of 14 N-terminal and 12 C-terminal amino acids are completely conserved or almost completely conserved, respectively, among nine human rotavirus VP3 genes that have been sequenced. In addition, there is conservation of arginine at the two trypsin cleavage sites as well as conservation of clusters of amino acids in different regions of the two VP3 cleavage products, VP8 and VP5. Three distinct forms of VP3 were identified among the nine human rotavirus strains analyzed. Three symptomatic rotaviruses (serotypes 1, 3, and 4) possess highly related VP3 genes (92.2 to 97% nucleotide identity). Two symptomatic serotype 2 rotaviruses possess VP3 genes which are even more closely related to each other (98.6% nucleotide identity) and only moderately related to the aforementioned VP3 genes of serotypes 1, 3, and 4 (87.4 to 88.2% nucleotide identity). The four asymptomatic rotaviruses, which constitute the third group, possess highly related VP3 genes (95.5 to 97.5% nucleotide identity) which are distinct from those of the virulent rotaviruses (73 to 74.8% nucleotide identity). At 91 positions in the protein sequence of VP3, an amino acid is conserved among the asymptomatic rotaviruses, while a different amino acid is conserved among the symptomatic rotaviruses. Notably, five regions are conserved among the symptomatic rotaviruses, while a different set of sequences are conserved among the asymptomatic rotaviruses. It is possible that some or all of these regions of sequence dimorphism may be responsible for the difference in virulence of these two groups of human rotaviruses. There are 13 regions in the VP3 protein sequence which exhibit the greatest variability; the majority of these variable regions are observed between amino acids 106 to 192. These regions may represent potential antigenic sites related to heterotypic rotavirus neutralization.

Amino Acid Sequence↗

PubMed1988

Measurement of hyphema: a clinical method.

The purpose of this study was to devise a simple and reliable method of accurately measuring hyphema in the anterior chamber. Simple measurements of specific ocular characteristics, namely the corneal diameter and the vertical height of the blood column, are all that is required. Reference tables were generated to determine the amount of blood in the anterior chamber, and the percentage of volume occupied by blood.

Anterior Chamber↗

PubMed1988

Aqueous humor flow rate and intraocular pressure during and after pregnancy.

Intraocular pressure and aqueous humor formation rate have been determined from the first trimester of pregnancy through term, with further determinations 3 months postpartum, in 7 patients. The intraocular pressure showed a consistent, statistically significant fall during pregnancy, returning to values seen in early pregnancy after delivery. Aqueous humor formation rate showed no change during pregnancy. The data indicate that the sustained elevated hormonal levels during pregnancy, either directly or indirectly, cause an increase in fluid outflow conductance from the eye without altering the rate of fluid entry.

Adult↗

PubMed1988

Topical indomethacin and prostaglandins in normal and aphakic rabbit eyes.

Lenses were removed from rabbit eyes using an extracapsular technique. Animals were in three groups; no treatment (NT), post-treatment (PT) and pre- and post-treatment (PPT). Treatment consisted of 2% topical indomethacin given three times a day after surgery, except for the PPT group that received 3 drops on the day prior to surgery and drops at 3 hours and 1 hour before surgery. Prostaglandin levels in ocular tissues and fluids were determined at 7, 14 and 21 days post-surgery. Indomethacin decreased prostaglandin formation in most ocular tissues, and was more effective in the PPT group than in the PT group. The data indicate that topical indomethacin suppresses prostaglandin formation from ocular tissues, and that local prostaglandin release from retina and choroid can provide locally high prostaglandin concentrations, regardless of their source, after lensectomy.

Administration, Topical↗

PubMed1988

Cell turnover in ciliary epithelium compared to other slow renewing epithelia in the adult mouse.

Adult albino mice received tritiated thymidine either injected subcutaneously (333 microCi) every 6 hours for up to 36 hours, or administered in their drinking water for up to 74 days (about 45 microCi/day). Tissue sections were examined with autoradiography to determine the distribution of the label. Animals receiving subcutaneous injections showed no labeled cells in the choroid plexus epithelium and only one cell of 6600 cells counted in the ciliary epithelium was labeled. Animals exposed to the isotope in their drinking water for 74 days showed considerable uptake of label in hepatocytes (15%) and cortical kidney tubules (17%), whereas ciliary and choroid epithelia showed very low uptake at 0.25% and 0.01%, respectively. The data show that the ciliary and choroid epithelia have a very slow turnover rate compared to other slow renewing tissues, and, under normal conditions, these tissues are not renewed in the animal's adult life span.

Animals↗

PubMed1988

Effects of intracameral hydrogen peroxide in the rabbit anterior chamber.

The effects of intracameral injection of hydrogen peroxide were examined using different techniques in young (4 to 6 weeks of age, approximately equal to 500 g) and adult (3 to 6 months of age, 2.5 to 3.5 kg) rabbits. A response occurred that included changes in intraocular pressure, increased permeability of the iris vasculature, and swelling of the ciliary processes. The initial fall in intraocular pressure was the same in young and adult rabbits and the time to recovery of normal intraocular pressure was statistically the same in young rabbits as in adults. The loss of iris vascular integrity was more pronounced in adult animals, as judged by the appearance of fluorescein in the iris and anterior chamber. Microscopy revealed that the ciliary processes of young rabbits were unaffected by hydrogen peroxide, whereas in adult animals considerable swelling of the ciliary processes occurred. No polymorphonuclear leucocytes were observed in micrographs, ruling out their involvement in the response. The rate of loss of injected hydrogen peroxide from the anterior chamber was significantly longer in adult relative to young animals. Young animals had statistically higher catalase activity (U/mg wet weight) in iris and corneal endothelium than older animals. Differences exist in both the anterior segment response to, and the rate of clearance of, intracameral hydrogen peroxide injection in rabbits of at least two different ages that may reflect the differences found in tissue catalase concentrations.

Animals↗

PubMed1987

Effect of carbachol on rabbit corneal endothelium.

We investigated the current reformulation of the commercially available intraocular preparation of carbachol for its effect on corneal thickness and endothelial cell ultrastructure. A 15-minute perfusion in the specular microscope with 0.01% carbachol caused a significant increase in the corneal swelling rate, which returned to control values after 75 minutes of reperfusion with Krebs Ringer bicarbonate solution. Continued reperfusion with Krebs Ringer bicarbonate solution led to the final average corneal swelling rate being statistically similar to that of controls over the entire 180-minute perfusion period. Transmission and scanning electron microscopy demonstrated no changes in endothelial cell ultrastructure.

Animals↗

PubMed1987

A novel arachidonic acid metabolite with stimulatory effect on PHA-induced mitogenesis of lymphocytes.

The isolation of a novel arachidonic acid (Aa) metabolite from the supernatant of unstimulated human cord blood mononuclear leucocytes is reported. The metabolite, arbitrarily named 'compound 4' is neither a known lipoxygenase nor a cyclooxygenase product. 'Compound 4' was added to PHA-stimulated peripheral blood mononuclear leucocytes (PBML) from healthy blood donors, from mothers at term and from patients with immunodeficiency. 'Compound 4' induced an increase in the 3H-TdR incorporation by the maternal PBML and by the PBML from patients with various immunodeficiencies such as Wiskott-Aldrich syndrome and common variable immunodeficiency, whereas it had no effect on the proliferation of PBML from blood donors.

Arachidonic Acid↗

PubMed1987

Regional ocular blood flow after chronic topical glaucoma drug treatment.

The effects of a chronic three times a day treatment over a 5 to 6 week period of rabbit eyes with 1 of 5 topically applied glaucoma drugs on ocular blood flow was determined using a radioactive microsphere technique. The drugs employed were timolol (0.5%), pilocarpine (4%), epinephrine (2%), norepinephrine (2%), and ecothiophate iodide 0.125%). The results showed that epinephrine statistically decreased blood flow to the iris and ciliary processes while not to the posterior uveal tissues or optic nerve head. Pilocarpine also showed this same trend, while the differences were not statistically significant. Other drugs were without effect on regional ocular blood flow.

Animals↗

PubMed1987

Centripetal movement of fluorescein dextrans in the cornea: relevance to arcus.

The centripetal movement of fluorescein and fluorescein-labelled dextrans (4 to 150 kD) from sclera or cut edge of the cornea was determined in isolated rabbit corneas at 4 and 24 h. Corneas were divided into 5.5 mm diameter central core, inner 5.5 to 8 mm donut, 8 to 12 mm peripheral donut and, where applicable, scleral rim. For all molecules greater than sodium fluorescein (376 D) tracer concentrations in the 5.5 mm core and the 5.5 to 8 mm donut were equal. Without sclera rim, the more central portions of the cornea (5.5 mm core and 5.5 to 8 mm donut) had tracer concentrations equal to those of corneas-with-sclera for all tracers greater than 10 kD. The tracer concentrations in the central cornea were the same in the presence or absence of sclera. The data indicate a physiological barrier to the lateral diffusion of molecules greater than 10 kD between the peripheral and more central cornea.

Animals↗

PubMed1987

Effect of oral or intravenous pentoxifylline on ocular and optic nerve blood flow.

The effect of oral and intravenous pentoxifylline 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 30 min after intravenous injection of 20 mg of pentoxifylline, or 2-3 h after oral administration of 20 mg of pentoxifylline. Blood flow measurements were determined for the iris, scraped ciliary processes, choroid, retina, and optic nerve. The only statistically significant difference noted was for blood flow in the optic nerve in the oral- versus intravenous-treated groups. Neither was significantly different from the control group.

Administration, Oral↗

PubMed1987

Prostaglandin involvement in the responses of the rabbit eye to water-soluble marihuana-derived material.

Both anticoagulants (heparin and streptokinase) and non-steroidal anti-inflammatory compounds (aspirin and indomethacin) were used against a water-soluble derivative of marihuana, MDM. While the anticoagulants had no effect on the ocular effects of MDM, both aspirin and indomethacin altered the time course and effected the MDM-induced reduction of intraocular pressure. The usual initial hypertensive effect of intravenous MDM was eliminated and the later intraocular pressure fall occurred earlier as well as being inhibited by about 35 to 50%. Assay for prostaglandins revealed that intravenous MDM (3.86 micrograms) caused a marked rise in PGE2 concentration of the aqueous humor and iris-ciliary body during the first hour or two after administration of MDM, but normal values occurred at 4, 6, and 8 hours when the intraocular pressure is reduced by up to 60%. Following intravitreal MDM (0.002 microgram), however, the PGE2 levels remained unchanged over 24 hours, despite the induction of a fall in intraocular pressure between 14 and 18 hours which lasts for many hours. Prostaglandin appears to be involved in the hypertensive phase of intraocular pressure change after intravenous MDM injection; and, while the fall in intraocular pressure may contain a component partially mediated by prostaglandins, there is no evidence that intravitreal MDM induces any effect on prostaglandin levels. The involvement of prostaglandins, therefore, in the mediation of MDM-induced ocular hypotensive effects is apparently small.

Animals↗

PubMed1987

Sodium and bicarbonate fluxes in regenerating rabbit corneal endothelium.

Rabbit corneal endothelia were subjected to a cryoinjury (-70 degrees C for 15 sec) and sodium and bicarbonate fluxes were determined at various times after induction of the endothelial destruction. A complete monolayer of cells was present by 4 days that consisted of large cells that underwent division over the next 16 days. Unidirectional sodium fluxes were unaltered by the transformation from large to normal sized hexagonal cells. Unidirectional bicarbonate fluxes showed an increase in Jendostr coupled with a decrease in the net Jstrendo flux. As the cells became smaller these bicarbonate fluxes returned to normal values. The data indicate that the cell margin/cell size ratio is not related to the flux rates, thus the paracellular pathway increase with healing is not related to the passage of either sodium or bicarbonate. Secondly, the data indicate separate effects on both sodium and bicarbonate, suggesting that transendothelial movement of the ions can be separated and that they are not necessarily linked in passage across the endothelium.

Animals↗

PubMed1987

Mussel adhesive protein: permeability characteristics when used as a basement membrane.

Mussel Adhesive Protein (MAP) was applied to either denuded rabbit cornea, or dialysis membrane with a 50,000 dalton molecular weight cut-off. The permeability of corneal endothelium or bare stroma was compared with demambranized stroma coated on one surface with MAP. The permeability of dialysis membrane, both in the presence and absence of MAP, was also determined to inulin (5,000 daltons) and dextran (40,000 daltons). Corneal endothelial permeability was much less than that of bare stroma, and coating denuded stroma with MAP on one surface had no effect on stromal permeability. Dialysis membrane permeability was not reduced after coating with different thickness of MAP, indicating that MAP offers little resistance to the passage of even large non-electrolytes and can serve as a basement membrane for cellular or tissue attachment without impairment of nutritional supply to the overlying cells.

Animals↗

PubMed1987

Water soluble high molecular weight components from plants with potent intraocular pressure lowering activity [corrected and republished ariticle originally printed in Curr Eye Res 1987 May;6(5):733-4].

Previous work in our laboratory has shown that Cannabis sativa (marijuana) contains water-soluble, high molecular weight components that have extremely potent intraocular pressure (IOP) lowering activity. Aqueous extraction of other plants has now shown that a number of them also contain components with potent IOP lowering activity in rabbits. These include tobacco, cabbage, lettuce, several greens, Senecio anonymus, Erigeron philadelphicus, and several others. Not all plants tested were active, however, indicating that while more ubiquitous than originally thought, these materials are not apparently extractable from all plants. The chemical composition of the active fraction from tobacco was found to be different from that derived from Cannabis sativa.

Animals↗

PubMed1987

Hydrogen peroxide in the rabbit anterior chamber: effects on glutathione, and catalase effects on peroxide kinetics.

Intracameral hydrogen peroxide (H2O2) is cleared at a faster rate in young (t1/2, 93 seconds) than in adult (t1/2, 109 seconds) rabbits. Extrapolated zero time concentrations of H2O2 were 3.3 mM in adults and 3.2 mM in young. The more rapid disappearance of H2O2 correlated with greater catalase levels in iris (35%) and corneal endothelium (50%) in young as compared to adult animals. Catalase levels have been found to be reduced in ocular tissues with 3-amino-1H-1,2,4-triazole (3AT) in a dose-related manner up to 6 ml/kg of an intravenous 3M solution. Iris and ciliary processes showed a linear reduction with dose, while corneal endothelium, liver and lung reached near maximal decreases in catalase activity at 2, 4, and 6 ml/kg, respectively. 3AT caused a significant dose-dependent extension of the rate of clearance of H2O2 from the anterior chamber, that was directly related to catalase loss. The t1/2 for H2O2 disappearance in adult animals increased from 109 seconds with no 3AT, to 147 seconds after 2 ml/kg 3M 3AT, to 161 seconds after 4 ml/kg 3M 3AT and 184 seconds after 6 ml/kg 3M 3AT. Corneal endothelial oxidized glutathione levels were transiently increased after intracameral hydrogen peroxide. Considering the sum total of all tissues of the anterior segment, specific incremental decreases of catalase generated by intravenous 3AT caused the t1/2 of H2O2 clearance from the anterior chamber to become longer, while the reducing power of anterior segment tissues excluding lens epithelium is related clearly to the systemic dose of 3AT.(ABSTRACT TRUNCATED AT 250 WORDS)

Amitrole↗

PubMed1987

3-amino-triazole effects on the eye of young and adult rabbits in the presence and absence of hydrogen peroxide.

3-aminotriazole (3AT) is known to reduce catalase levels in ocular tissues when given intravenously or orally. Rabbits were given either 4 ml/kg of a 3M solution of 3AT intravenously or a 2% solution as drinking fluid. Intravenous 3AT administration was followed at 4 hrs by an intracameral injection of hydrogen peroxide (H2O2) to give an aqueous humor concentration of 3.2 mM in young (4-6 weeks of age) and a 3.3 mM in adult (6 months of age) rabbits. Tissues were taken for microscopy at either 6 or 24 hours after intracameral H2O2. Neither oral nor intravenous 3AT alone in adult rabbits, or intravenous 3AT in young rabbits, had any effect on either iris, ciliary process, or corneal endothelial morphology. After oral 3AT in adult rabbits, H2O2 caused highly edematous ciliary processes with dilated vessels; corneal endothelial cells were swollen. Previous studies in adult and young rabbits have shown that intracameral H2O2 alone caused few morphological changes in young, but marked changes in the adult that correlated with the 35 to 50% lower catalase levels found in iris and corneal endothelium, respectively, in adult ocular tissues. Young rabbits pre-treated with intravenous 3AT, when examined at 6 and 24 hours after intracameral H2O2, showed swollen ciliary processes, vessel dilation, alteration of the pigment epithelium and corneal endothelial damage. In non 3AT-treated young rabbits, H2O2 caused only minor morphological changes. In adult animals at 6 and 24 hours after intracameral H2O2 the ciliary processes were edematous in the absence of 3AT; after intravenous 3AT and intracameral H2O2 the changes were even more marked, with very severe swelling of ciliary processes and corneal endothelial damage. It is apparent that the decrease in catalase caused by 3AT allows H2O2 to induce damage even in young animals where it usually does not induce morphological changes. In adult animals, the effects of H2O2 are enhanced in the presence of 3AT.

Administration, Oral↗

PubMed1987

Corneal storage in MK medium and K-Sol. Effect on ionic and non-ionic fluxes.

Rabbit corneas were stored at 4 degrees C for 3, 7 or 14 days in either modified MK medium or K-Sol. Corneal endothelial permeability to inulin following storage in modified MK was significantly less at each time examined than that found in corneas stored for either 3, 7 or 14 days in K-Sol. Inulin permeability after storage in K-Sol was increased at all times relative to unstored control corneal tissue, but only at 7 and 14 days in MK medium. Dextran permeability was similar following 3 days of storage in either solution, but dextran permeability following storage in modified MK was significantly less than the values found in corneas stored for 7 and 14 days in K-Sol. Dextran permeability was not significantly increased relative to control, at any storage time in MK medium but was increased at 7 and 14 days in K-Sol. Inulin and dextran permeabilities after storage in MK medium were maintained more closely to values found in fresh tissue than corneas stored in K-Sol. Net endothelial sodium fluxes following storage in modified MK medium were markedly less than those found in corneas stored for 3, 7 and 14 days in K-Sol. Net sodium fluxes are maintained better in K-Sol than in MK medium relative to control values. Net bicarbonate fluxes following storage in modified MK medium were significantly less than the 3-day values in K-Sol, but similar to the values after 7 and 14 days of K-Sol storage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗