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Biomedical subjects

E J Morris

Publications and source records attributed to E J Morris.

At least 37 records · Page 2Linked to original sources
PubMed1994

Early clinical experience with topical collagen in vascular wound care.

An 82-year-old woman had undergone 4 continuous years of home health treatment for bilateral venous ulcers of the lower extremities. Previous wound treatments, consisting of cleansing with soap and water, hydrogen peroxide, saline solution-impregnated dressings; hydrophilic beads, silver sulfadiazene (Silvadene), multiantibiotic (Neosporin) and Silvadene ointments, and hydrocolloids, had been tried with limited success. A regimen of wound management consisting of cleansing with normal saline solution to cleanse the wound of exudate and debris and application of collagen particles directly to the wound, followed by application of a hydrocolloid dressing, was applied to these wounds. These measures were supported by bilateral elevation of the lower extremities to aid circulation. As a result, rapid wound healing occurred within approximately 80 days.

Aged↗
PubMed1994

Rearrangement of mRNAs for costamere proteins during costamere development in cultured skeletal muscle from chicken.

Mature skeletal myofibrils are surrounded by costameres, ribs of metavinculin, vinculin, intermediate filaments, and other proteins that connect the myofibril to the extracellular matrix. Costameres have recently been shown to be the sites at which the forces generated by the myofibril are transduced laterally into the extracellular matrix. We observed costameres developing in cultured skeletal muscles, grown in micromass culture from cells taken from embryonic chicken leg. We detected proteins by immunofluorescence and mRNA by in situ hybridization. Antibody and probe signals were imaged by laser scanning confocal microscopy. Antibody to vimentin protein is first detected in stripes in register with the Z line of the myofibril, at approximately day 12 after fusion; soon thereafter probe to vimentin mRNA is also detected in the same stripes. Optical sections indicate that vimentin mRNA and protein are very close, no more than 0.1 mm apart and possibly in immediate contact. Antibody to vimentin is detected in stripes only in cells that twitch spontaneously. Antibodies and probes to desmin and vinculin protein and mRNA are next detected in stripes of the same periodicity, at approximately day 17 after fusion. Vinculin protein (but not mRNA) is detected at focal contacts much earlier in development. Controls for bleed through of fluorescence, RNase H sensitivity, hybridization without probe, and binding to the myofibril all gave appropriate results. Probes to glyceraldehyde-3-phosphate dehydrogenase, a glycolytic enzyme, stained diffusely and did not associate with the myofibril. These results show that components of the costamere arrive at the structure in a defined sequence, and that mRNA organization is a conspicuous, precise and temporally controlled aspect of costamere development. These results may have wider implications. In these cells, some mRNAs are positioned with submicrometer precision in space and differentially over time. Particular mRNAs differ in the time and place of such positioning. This implies both that cellular structures provide physical cues for such positioning and that mRNA contains information that interacts with such cues in a message-specific manner. If such precision in mRNA location is found in other somatic cells, it could have significant implications for the ways in which cells generate and maintain cellular structures.

Animals↗
PubMed1993

Effect of uncorrected refractive errors upon central visual field testing.

An investigation of the effects of uncorrected refractive errors upon a central visual field examination has been made with a view to establishing what the likely effects would be of omitting a refractive correction when screening the visual field with a threshold related, supra-threshold strategy on the Henson CFA3000. The results indicate that, while a linear relationship exists between the extent of threshold elevation and the product of residual refractive error and pupil size, the scatter in the results means that accurate predictions cannot be made in individual cases. The threshold elevation was found to be independent of eccentricity (within the central 21 degrees from fixation) and did not increase the variability of results. These last two findings indicate that uncorrected refractive errors are unlikely to affect the sensitivity of the threshold related, supra-threshold strategy to localized visual field defects.

Adult↗
PubMed1987

Senile dementia of the Alzheimer's type: an important risk factor for serious falls.

In a longitudinal study of senile dementia and healthy aging, the occurrence of serious falls was examined in participants with senile dementia of the Alzheimer's type (SDAT) (n = 44) and in cognitively healthy elderly control participants (n = 56) over a 4-year period. Falls occurred in 36% of SDAT individuals versus 11% of controls. The higher frequency of falls in demented participants was not explained by greater neurologic deficit nor by increased drug use compared with controls. However, males with SDAT who reported falls, had higher mean blood pressures and were more likely to be medicated than males with SDAT who did not fall. These differences were not observed in women. Falls in SDAT participants were associated with an increased rate of institutionalization. SDAT is an important risk factor for serious falls, and falls are associated with loss of independence in demented patients.

Accidental Falls↗
PubMed1987

Identification and preliminary characterization of a Streptococcus sanguis fibrillar glycoprotein.

Cell surface fibrils could be released from Streptococcus sanguis 12 but not from strains 12na or N by freeze-thawing followed by brief homogenization. Fibrils were isolated from the homogenate by ultracentrifugation or ammonium sulfate precipitation. Electron microscopy demonstrated the presence of dense masses of aggregated fibrils in these preparations. Under nondenaturing conditions, no proteins were seen in polyacrylamide gel electrophoresis (PAGE). Sodium dodecyl sulfate (SDS)-PAGE analysis revealed a single band stained with Coomassie blue and periodic acid Schiff stain with a molecular weight in excess of 300,000. The protein has been given the name long-fibril protein (LFP). The molecule was susceptible to digestion with subtilisin, pronase, papain, and trypsin, but was unaffected by chymotrypsin or muramidases. Attempts to dissociate the protein into smaller subunits with urea, guanidine, sodium thiocyanate, and HCl were unsuccessful. Gel filtration on a column of Sephacryl S-400 in the presence of 2% SDS resulted in elution of the protein at the void volume. Antibody raised against the LFP excised from an SDS-PAGE gel reacted with long fibrils on the surface of strain 12 and with isolated fibrils by an immunogold labeling technique. Monoclonal antibody reactive with LFP in SDS-PAGE also reacted with fibrils present on the cell. Antisera raised against the fibrils inhibited adherence to saliva-coated hydroxyapatite.

Amino Acids↗
PubMed1987

Visual motion processing and sensory-motor integration for smooth pursuit eye movements.

The function of smooth pursuit is to keep the fovea pointed at a small visual target that moves smoothly across a patterned background. Chemical lesions, single cell recordings, and behavioral measures have shown that the cortical motion processing pathways form the afferent limb for pursuit. Important areas include at least the striate cortex and the middle temporal visual area, and probably the medial superior temporal visual area and the posterior parietal cortex. We argue that the visual inputs are transmitted through a simple sensory motor interface in the pons, to the efferent limb in the brain stem and cerebellum. The efferent limb uses neural velocity memory to maintain pursuit automatically. We present evidence that the velocity memory is provided, at least in part, by eye velocity positive feedback between the flocculus of the cerebellum and the brain stem. Finally, we use a computer model to show how the maintenance of pursuit can be simulated on a millisecond time scale. The structure and internal elements of the model are based on the biological experiments reviewed in our paper. In the past five years, progress on the neural basis of pursuit eye movements has been rapid. Several areas of research have made substantial contributions, by using combinations of new and conventional methods. Many of the pathways that contribute to pursuit have been identified, and their physiological activity and functions are becoming understood. Continuing progress promises to yield an understanding of one specific form of visually guided movement, at the level of neuronal circuits and behavior, in the primate.

Animals↗
PubMed1987

Different responses to small visual errors during initiation and maintenance of smooth-pursuit eye movements in monkeys.

1. We have investigated the role of retinal and extraretinal signals in the initiation and maintenance of smooth-pursuit eye movements in trained rhesus monkeys. Visual targets were presented in open-loop conditions by using electronic feedback of eye position to form the command for target position. This allowed us to present stimuli that were stabilized with respect to the moving eye or to provide small, precisely controlled retinal position or velocity errors. 2. Pursuit was maintained with only small decreases in eye velocity if retinal errors were eliminated by stabilizing the tracking target in front of the fovea during pursuit at 15 degrees/s. This argues that the pursuit system employs "velocity memory" to maintain pursuit. We suggest that velocity memory is effected by an extraretinal signal derived from positive feedback of eye-velocity commands. 3. Small retinal position errors caused smooth eye accelerations if imposed during pursuit, but were ineffective for initiating the transition from steady fixation to pursuit. Small retinal velocity errors were effective both for initiating pursuit from steady fixation and for altering eye velocity during pursuit. 4. Retinal position errors were effective at changing smooth eye velocity in a variety of conditions that required prior activation of the pursuit system. These include pursuit with or without a stationary background, pursuit with a background that was stabilized with respect to the eye, pursuit with combined eye and head motion (cancellation of the vestibuloocular reflex), and use of pursuit to suppress optokinetic nystagmus. Position errors were ineffective during fixation of stationary targets, even if head motion was provided to evoke the smooth eye velocity of the vestibuloocular reflex. 5. We conclude that retinal position errors are effective only after the pursuit system has been activated. It follows that pursuit initiation involves an active transition from steady fixation and that this transition is normally triggered by retinal velocity errors but not by retinal position errors.

Animals↗
PubMed1985

Cell surface components of Streptococcus sanguis: relationship to aggregation, adherence, and hydrophobicity.

Cell surfaces of aggregation, adherence, and hydrophilic variants of Streptococcus sanguis were compared with cell surfaces of the parent strain with regard to their protein and antigenic constituents. Cell surface molecules were released by digestion with mutanolysin. Extraction with sodium dodecyl sulfate (SDS) urea, lithium diiodosalicylate, and boiling water did not solubilize any material which stained with AgNO3 in an SDS-polyacrylamide gel electrophoresis gel. The parent organism S. sanguis 12, which aggregates in saliva, adheres to saliva-coated hydroxyapatite and is hydrophobic, was found to possess a prominently staining 160,000 molecular weight (MW) protein. This protein was almost completely absent from strain 12na, a hydrophobic nonaggregating variant, and was completely absent from the hydrophilic nonaggregating strain 12L. Trypsinization of strain 12 resulted in the coincident loss of the 160,000-MW protein and the ability to aggregate in saliva. Trypsin treatment reduced but did not eliminate the hydrophobic character of the cells. Boiling destroyed their ability to aggregate, but did not alter their hydrophobicity. Cell wall digests of strain 12 contained a number of proteins which were absent from strains 12na and 12L. Mutanolysin digests of cell walls of the hydrophilic strains contained almost no material that was visible in a silver-stained SDS-polyacrylamide gel electrophoresis gel. Culture supernatants contained a number of proteins which were immunologically cross-reactive with cell surface proteins. The hydrophilic organisms released a number of 60,000- to 90,000-MW proteins not seen in culture supernatants from the parent strain.

Adhesiveness↗
PubMed1984

Adherence of Streptococcus sanguis to saliva-coated hydroxyapatite: evidence for two binding sites.

The characteristics of bacterial adherence to saliva-coated hydroxyapatite were examined for a salivary aggregating strain of Streptococcus sanguis, strain 12, and for its nonaggregating variant, strain 12na. Both strains were found to adhere in similar numbers to saliva-coated hydroxyapatite that had been preincubated at 4 degrees C overnight. Preincubation of saliva-coated hydroxyapatite overnight at 37 degrees C reduced subsequent adherence of S. sanguis 12 by approximately 10%, whereas adherence of S. sanguis 12na was reduced by over 80%. Preincubation at 37 degrees C in the presence of neuraminidase reduced adherence of S. sanguis 12 by over 90% and caused some additional reduction in adherence of S. sanguis 12na. The data were analyzed with Langmuir isotherms, Scatchard plots, and Hill plots. Some evidence of cooperativity was seen. A peak in the Scatchard plot for S. sanguis 12 binding to saliva-coated hydroxyapatite preincubated at 4 degrees C disappeared after preincubation at 37 degrees C, suggesting the loss of a salivary receptor. Many more organisms were found to bind when adherence was measured by assays counting the number of organisms remaining in suspension after the beads had settled. These weakly binding organisms, which were removed by washing, demonstrated adherence characteristics similar to those of the firmly bound organisms. Both strains were strongly hydrophobic. It is proposed that the binding of S. sanguis 12 and 12na involves two types of receptor on the salivary pellicle. One type of receptor is stable at 37 degrees C, but sensitive to neuraminidase; the second type is inactivated by prolonged incubation at 37 degrees C. S. sanguis 12 may bind to both types of receptor, whereas S. sanguis 12na binds only to the second type. The neuraminidase-sensitive receptor might be involved in saliva-mediated aggregation.

Adhesiveness↗
PubMed1983

Aggregation of Streptococcus sanguis by a neuraminidase-sensitive component of serum and crevicular fluid.

A number of strains of Streptococcus sanguis were found to aggregate in nonimmune serum and in crevicular fluid. All strains which aggregated in serum also aggregated in saliva, but some strains which aggregated in saliva did not aggregate in serum. Aggregation was destroyed by treatment of serum or crevicular fluid with neuraminidase and was inhibited by gangliosides. Treatment of serum with proteases reduced aggregating activity. Adsorption of serum to hydroxyapatite did not reduce the aggregating activity. The aggregating factor was partially purified by gel filtration and polyacrylamide gel electrophoresis and was found to be an acidic glycoprotein with a molecular weight of greater than 200,000, comprised of subunits with molecular weights of approximately 100,000. It did not appear to be an immunoglobulin and could not be identified with any other serum component tested. The possible role of the aggregating factor in providing nonimmune protection against colonization of S. sanguis in the gingival crevice and blood is discussed.

Animals↗
PubMed1978

Electron microscopy of the microbial populations present and their modes of attack on various cellulosic substrates undergoing digestion in the sheep rumen.

Cotton fibers and various cell wall preparations from grass leaves and from the feces of sheep fed on dried grass were placed in the sheep rumen in bags made from 5-mum-mesh nylon cloth. After periods of from 3 to 48 h, bags were removed, and the contents were fixed, embedded, sectioned, and stained for electron microscopy. Some of the bacteria present were seen to be closely associated with the cell walls, either tunneling within them or making very close contact. Evidence was obtained for differential digestion of cell walls and of the layers within them. Distinct differences were noticed between bacterial populations attacking the more susceptible wall types and those attacking feces cell walls and cotton fibers. Among the latter, the dominant form was a long, thin rod with a typical gramnegative cell wall structure, different from that described for Bacteroides succinogenes S85 or for Butyrivibrio fibrisolvens.

Journal Article↗
PubMed1975

Acetyl groups in cell-wall preparations from higher plants.

O-Acetyl groups were detected by i.r. spectroscopy in cell-wall preparations from grasses and other higher plants and their presence was confirmed chemically. The amounts present are likely to influence both the physical state of the cell-wall polysaccharides and also their digestion by enzymes.

Acetates↗
PubMed1969

Blind river dolphin: first side-swimming cetacean.

The blind river dolphin (Platanista gangetica), first written about by Pliny the Elder in A.D. 72, was found (10 November 1968) to be the first known side-swimming cetacean. The rudimentary eye lacks the lens, but anatomical evidence suggests that the eye may serve as a light sensor. The underwater sound emissions of this species, although similar to those of the Amazon River dolphin (Inia geoffrensis), appear to be produced constantly.

Acoustics↗
PubMedDate not supplied

Comparison of transesophageal color flow Doppler imaging of normal mitral regurgitant jets in St. Jude Medical and Medtronic Hall cardiac prostheses.

Transesophageal color flow Doppler imaging of mitral mechanical prostheses is now widely used. This method eliminates the frequent problems of acoustic shadowing and flow masking that are commonly seen with a transthoracic Doppler study of mechanical mitral prostheses. Transesophageal color flow Doppler imaging was performed postoperatively in seven patients who had received St. Jude Medical mitral prostheses (St. Jude Medical, Inc., St. Jude, Minnesota) and in six patients who received Medtronic Hall mitral valves (Medtronic, Inc., Minneapolis, Minnesota). Maximal systolic regurgitant jet length and area determinations were obtained in all patients. A comparison of maximal jet lengths and areas for each type of mechanical prosthesis demonstrated that the Medtronic Hall prostheses produced longer maximal jet lengths (p = 0.0001) and larger jet areas (p = 0.0009) than those produced by the St. Jude Medical mitral valves. Medtronic Hall prostheses produce a large centrally directed jet, whereas St. Jude Medical prostheses typically generate three smaller jets. Recognition of these differences in transesophageal color flow Doppler images in these commonly used cardiac valve prostheses is necessary to avoid misinterpretation of the normally large systolic regurgitant jet of the Medtronic Hall prosthesis as representing prosthetic dysfunction.

Adult↗