PubMed Health⌕ Search

Biomedical subjects

D A Morris

Publications and source records attributed to D A Morris.

At least 19 recordsLinked to original sources
PubMed2000

Transmembrane auxin carrier systems--dynamic regulators of polar auxin transport.

Recent investigations of the biochemistry, physiology and molecular genetics of polar auxin transport have greatly advanced our understanding of the process and of the part it plays in the regulation of development and in the responses of cells, tissues and organs to internal and external stimuli. The molecular and physiological characterization of mutants which exhibit lesions in polar auxin transport has led to the isolation and sequencing of genes which encode putative components of auxin carrier systems, or proteins which directly or indirectly regulate these systems. This work has revealed that specific auxin uptake and efflux carriers are coded not by single genes, but by whole families of genes, the expression of which is tissue or stimulus specific. Furthermore, evidence is accumulating rapidly that at least the auxin efflux carrier is a multi-component system consisting of both catalytic and regulatory subunits, including a separate phytotropin-binding protein. Other genes have been tentatively identified which code proteins that regulate the expression of genes coding auxin carrier components, or which regulate the intracellular traffic or activity of auxin carriers. Investigations of the turn-over and Golgi-mediated trafficking of auxin carrier proteins have revealed that essential components of at least the efflux carrier have a very short half-life in the plasma membrane and are replaced without the need for concurrent protein synthesis, leading to speculation that they might cycle between internal stores and the plasma membrane. The way is now clear for the development of specific molecular probes with which to investigate the intracellular transport and targeting of auxin carrier proteins.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1999

Risk factors for early filtration failure requiring suture release after primary glaucoma triple procedure with adjunctive mitomycin.

PURPOSE: Postoperative release of scleral flap closure suture is useful in trabeculectomy combined with cataract surgery. We determined risk factors for early filtration failure requiring suture release during the first month after primary glaucoma triple procedure. METHODS: The medical records of 71 consecutive patients with primary open-angle glaucoma who underwent a primary glaucoma triple procedure (primary trabeculectomy, phacoemulsification, and posterior chamber intraocular lens implantation) were reviewed. Suture release had been performed in 24 of the patients for early filtration failure with postoperative intraocular pressure greater than the target value during the first postoperative month. The long-term filtration failure was defined according to 2 criteria based on medical dependency and requirement of additional surgical procedure for intraocular pressure control. Cox proportional hazards multivariate analysis was performed to identify independent risk factors. RESULTS: African American race (P = .02), more than 2 preoperative glaucoma drugs (P = .02), and intraocular pressure greater than 14 mm Hg during the first postoperative week (P = .006) were identified as significant independent risk factors requiring suture release for filtration failure during the first postoperative month. Their significance was further confirmed by Kaplan-Meier survival analysis with Mantel-Cox log-rank test (P = .03, P = .02, and P = .001, respectively). CONCLUSIONS: African American race, more than 2 preoperative medications, and intraocular pressure greater than 14 mm Hg in the first postoperative week are major independent risk factors for initial filtration failure requiring suture release during the first month after primary glaucoma triple procedure. Presence of the risk factors may warrant a more aggressive antiproliferative regimen and/or earlier suture release.

Aged↗
PubMed1999

Foldable posterior chamber intraocular lens implantation in the absence of capsular and zonular support.

PURPOSE: To implant foldable posterior chamber intraocular lenses in the absence of capsular and zonular support. METHODS: Case reports. In two patients, two eyes with aphakia, lack of capsular or zonular support, and contact lens intolerance underwent the implantation of a silicone and an acrylic foldable posterior chamber intraocular lens, respectively. RESULTS: In the two eyes, final visual acuity was 20/25 and 20/50, respectively. No intraoperative vitreal, retinal, or choroidal complications were noted. The postoperative recovery was rapid, and there was minimal induced astigmatism. CONCLUSIONS: The implantation of foldable posterior chamber intraocular lenses in aphakic eyes without capsular and zonular support may result in fewer intraoperative complications. It also allows for faster postoperative recovery and less postoperative astigmatism.

Acrylates↗
PubMed1998

Use of autologous Tenon's capsule and scleral patch grafts for repair of excessively draining fistulas with leaking filtering blebs.

PURPOSE: To report the use of autologous Tenon's and partial-thickness scleral tissues for patch graft revisions of excessively draining fistulas associated with leaking filtering blebs. METHODS: Appropriate sized pieces of autologous Tenon's tissue and partial-thickness scleral tissue were dissected near the surgical sites and used as patch grafts to effectively repair excessively draining fistulas with leaking filtering blebs. RESULTS: Both Tenon's and partial-thickness scleral patch grafts were useful in adequately closing the excessively draining fistulas. CONCLUSION: Autologous Tenon's and scleral tissue patch grafts appear to be safe and effective for the repair of excessively draining fistulas, and are useful when patch grafts are unexpectedly needed.

Aged↗
PubMed1994

Postpartum blood pressure and insulin sensitivity in African-American women with recent preeclampsia.

Pregnancy-induced hypertension and preeclampsia are relatively common in nulliparous, inner-city, African-American, pregnant women and contribute to considerable maternal, fetal, and neonatal morbidity and mortality in that population. Recently, insulin resistance has been related to the development of hypertension in young African-Americans and hyperinsulinemia and elevated insulin-to-glucose ratios, suggesting insulin resistance, have been demonstrated in women with preeclampsia. To investigate whether insulin resistance existed postpartum and, therefore, independently of the pregnant state, the hyperinsulinemic, euglycemic technique was used 3 to 6 months postpartum to assess insulin sensitivity in 10 young, black, primiparous, inner-city women with recent preeclampsia and seven age-, weight- and body-mass-index-matched black women with healthy pregnancies. The age, weight, body-mass index, waist-to-hip ratio, the duration since parturition, and fasting plasma glucose and insulin were similar in the preeclamptic and control groups. During the clamp procedure, the insulin levels and mean diastolic blood pressure and mean arterial pressure were also similar for both groups; however, the mean systolic blood pressure of the preeclamptic group (123 +/- 3 mm Hg) was higher than that of the control group (114 +/- 2 mm Hg) (P < .05). Insulin-stimulated glucose disposal was not different between the preeclamptic (5.6 +/- 0.3 mg/kg/min) and control groups (5.7 +/- 0.7 mg/kg/min). This suggests that the elevation in postpartum systolic blood pressure may reflect a persistent abnormality of blood pressure homeostasis which is not associated with insulin resistance.

Adolescent↗
PubMed1988

Psychological concomitants of cystic fibrosis in children and adolescents.

Thirty cystic fibrosis (CF) and 30 matched control children and their parents were administered several psychiatric inventories including the child (DICA) and parent (DICA-P) versions of the Diagnostic Interview for Children and Adolescents, the Child Behavior Check List, the Hopelessness Scale, and the Piers-Harris Children's Self-Concept Scale. Data analysis revealed few differences in either psychopathological symptoms or psychiatric diagnoses between the CF and control children. The differences which did emerge were either physical in nature (reflecting somatic complaints) or did not depart enough from normal scores to merit the label of high psychopathology. The results are discussed in terms of the growing evidence that CF children do not suffer from greater psychopathology than do normal children.

Adaptation, Psychological↗
PubMed1987

Structure determination of five sulfated oligosaccharides derived from tracheobronchial mucus glycoproteins.

The structure of five sulfated oligosaccharide units of highly anionic tracheobronchial mucous glycoproteins, isolated from a cystic fibrosis patient's sputum, were established. Reduced oligosaccharides (84%) were released under alkaline borohydride conditions, and the acidic oligosaccharides (63%) were isolated by Dowex 1-X2 chromatography. Following the removal of acidic oligosaccharides possessing N-acetylneuraminic acid and L-fucose by lectin affinity chromatography a heterogeneous mixture of sulfated oligosaccharides was obtained. From this fraction, five short chain monosulfated oligosaccharides (S-I to S-V) were purified by sequential separation by SynChroprep AX300 anion exchange high pressure liquid chromatography, gel filtration on Bio-Gel P-2, and high voltage paper electrophoresis. Based on the results of carbohydrate composition, sequential exoglycosidase degradation, permethylation analysis, lectin affinity chromatography, and periodate oxidation, the following structures (where GalNAcol is N-acetylgalactosaminitol) were proposed for these oligosaccharides. (formula; see text)

Adolescent↗
PubMed1987

Recurrent conjunctival melanoma with neuroidal spindle cell features.

A 66-year-old white woman had had a 20-year history of flat primary acquired melanosis involving the left inferior forniceal and palpebral conjunctiva. Over the ensuring 12 years, the patient experienced multiple recurrences of invasive malignant melanoma that emerged from the progressive primary acquired melanosis. Two of these recurrences were composed of nonpigmented spindle cells, and in the most florid invasive malignant melanoma that developed, the spindle cells formed a nodule 7.5 mm thick. The spindle cells were organized into fascicles and small bundles, the latter separated by a loose stroma that was devoid of mucopolysaccharides. The fascicular and neuroidal features in this case were sufficiently well developed to suggest the incorrect diagnosis of a neural tumor or a neurofibroma. However, the presence of intraepithelial atypical melanocytes at the edge of the spindle cell lesion, the absence of mucopolysaccharides in the stroma, the mitotic activity, and the absence of intercellular reticulin fibers favored the diagnosis of a spindle cell invasive malignant melanoma. This morphologic variant of conjunctival melanoma is compared with related cutaneous lesions of melanoma featuring a spindle cell population.

Aged↗
PubMed1987

The pharmacokinetics of nedocromil sodium, a new drug for the treatment of reversible obstructive airways disease, in human volunteers and patients with reversible obstructive airways disease.

1. The plasma concentrations and urinary excretion of nedocromil sodium have been determined following single dose administration in six healthy volunteers dosed orally (1 mg kg-1) and intravenously (0.2 microgram kg-1 for 30 min). Similar parameters were measured in six volunteers and twelve asthmatic patients dosed by inhalation (4 mg). Multiple dose kinetic measurements were also made. 2. The intravenous data demonstrated that nedocromil sodium is a high clearance drug (10.2 +/- 1.3 ml min-1 kg-1). The data were fitted by a two compartment model with very rapid elimination from the central compartment (k10 = 0.088 +/- 0.021 min-1; beta = 0.013 +/- 0.002 min-1). 81% of the dose was excreted in the urine. 3. Oral absorption was low (2-3% of the dose) and contributed negligibly to the plasma profile after inhalation. 4. After inhalation of single doses of 4 mg in volunteers and patients plasma concentration rose rapidly, plateaued and then fell monoexponentially with a half-life of approximately 2 h. The data fitted a 'flip-flop' model with two absorption components. The extent of absorption was up to 6% of the dose with less in patients. 5. After multiple dosing with 4 mg four times daily for 7 days in volunteers negligible accumulation was observed. The pattern was similar in patients treated with 4 mg four times daily after 1, 6 and 12 months.

Administration, Inhalation↗
PubMed1984

Conjunctival synthetic fiber granuloma. A lesion that resembles conjunctivitis nodosa.

Histopathologic examination of forniceal conjunctival lesions excised from five young patients revealed granulomatous inflammation surrounding filamentous foreign material. Polarization microscopy, special histochemical stains, scanning electron microscopy and energy dispersive x-ray elemental analysis identified the inciting material as predominantly synthetic fabric fiber. Three of these cases initially were diagnosed as conjunctivitis nodosa, an inflammatory reaction to caterpillar setae. Many synthetic fibers contained numerous granules of titanium, barium, or zinc delustering agent, which served to differentiate them from natural fibers or caterpillar hairs. Synthetic fabric fiber is a previously unrecognized cause of conjunctival inflammatory mass lesions.

Adolescent↗
PubMed1980

Interaction of lysophosphatidylcholine with phosphatidylcholine bilayers. A photo-physical and NMR study.

Several photo-physical methods together with 31P-NMR have been used to investigate the effect of lysophosphatidylcholine on phosphatidylcholine bilayers. 31P-NMR shows that the permeability of the vesicle to Eu3+ increases sharply above approx. 40% lysophosphatidylcholine: fluorescence-quenching studies also show this type of behavior. Similar sharp changes in vesicle properties are observed via the photo-physical technique at this lysophosphatidylcholine/phosphatidylcholine composition. Fluorescence spectra of pyrene and pyrene carboxaldehyde show that increasing lysophosphatidylcholine composition increases the polarity of the environments of these probes up to 40% lysocompound. Above this composition the photo-physical properties of the probes slowly revert to those characteristic of the micellar lyso-compound. The pyrene fluorescence lifetime, the fine structure of the fluorescence, and the case of formation of pyrene excimer in these bilayer mixtures suggest that pyrene complexes weakly with the charged nitrogen of the choline group of the phosphatidylcholine and that the physical state of the system has a striking effect on this complexation process. Similar experiments with simple quaternary compounds lend strong support to this suggestion. The studies monitor in several ways the effect of bilayer composition on movement of molecules in these systems. The degree or site of solubilization of carcinogens is also uniquely affected by composition.

Kinetics↗
PubMed1976

Surface immune precipitation: a new method for rapid quantitative antigen analysis.

A new method for quantitative antigen analysis is described which precludes necessity for long incubation periods. The new technique, Surface Immune Precipitation (SIP), entails the application of an antigen sample droplet directly onto the surface of a gel containing antibody, the gel being supported by a reflecting substrate. Within a few minutes, a visible uniform opaque precipitate area appears at the location of the antigen droplet when antigen-specific antibody is present in the gel. The reflecting substrate enhances the contrast between the precipitate area and the surrounding gel. The scattering intensity of the precipitate, which may be measured with simple photodetection apparatus, is related to the antigen concentration in the droplet. Good correlation is demonstrated between the Surface Immune Precipitation method and radial immunodiffusion for the analysis of serum IgG.

Agar↗