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Biomedical subjects

J A Murphy

Publications and source records attributed to J A Murphy.

54 records · Page 3Linked to original sources
PubMed1978

Cilioexcitatory and cilioinhibitory processes initiated by light on two identifiable neuronal pigments in Mytilus edulis.

Two neuronal chromoproteins (red-haemoprotein and yellow-carotenoprotein) initiate changes in ciliary activity on the gill of Mytilus. Photic, electrical and chemical stimulation of these chromoproteins correlate with fluctuations in ionic (calcium and iron) deposits in gill bulk tissue samples. Microspectrophotometric measurements of chromoprotein spectral band patterns reveal two or three absorption maxima for carotenoprotein and haemoprotein respectively. Under aerobic conditions, cilioinhibition and cilioexcitation results after activation of carotenoprotein or haemoprotein respectively. Carotenoproteins are only engaged during gradual anoxia. Immediate anoxia renders both chromoproteins inoperative. Changes in ciliary activity initiated by photic stimulation of neuronal chromoproteins are abolished by denervation of the gill. It is postulated that photoactivation and/or release of specific neurotransmitters lead to transformations in chromoproteins with subsequent neuronal regulation of gill ciliary activity.

Animals↗
PubMed1976

Ultrastructure and elemental composition of dormant and germinating Diplodia maydis spores.

The ultrastructure of Diplodia maydis spores was studied in thin sections with a transmission electron microscope. Storage vacuoles were evenly distributed in the two cells. Some of the vacuoles that contained a dense osmiophilic sphere(s) were surrounded by a membrane, and had membranous aggregates around their periphery. The sport wall was composed of an electron-dense layer and an electron-translucent layer. An inner cytoplasmic membrane was present. Dormant and germinating spores were studied with scanning electron microscopy and also with a Si (Li) energy-dispersive X-ray analyzer. The dormant spore was ovate and usually two-celled with a central septum. Germination proceeded via a germ tube from the side of one end of the cell. Of several methods for preparation of specimens for X-ray analysis studied, freeze-dried spores mounted on carbon stubs and then further carbon coated gave the best results. X-ray analyses revealed that spore populations contained large amounts of Si, P, Cl, and K, smaller amounts of S and Ca, and trace amounts of Mg and Al. Analyses of single spores revealed high K and Cl and low P and Mg at one end of the cell with concomitant low K and Cl and high P and Mg in the central portion and other end of the cell. In two-celled germinating spores, high K and Cl occurred in the end of the nongerminating spore cell, whereas the germinating cell contained high P and Mg and low K and Cl. X-ray image maps revealed that K and Cl were located together at one end of the spore.

Calcium↗
PubMed1975

Dipotassium tetramethyl osmate: a stain for electron microscopy.

Methanol solutions of dipotassium tetramethyl osmate (DTMO) have been found to be useful as general stains in electron microscopic studies of plant and fungal ultrastructure. The stain solutions are easy to prepare, stable when anhydrous and convenient to use. Although generally similar in staining to lead citrate stains, some elements of cell ultrastructure appear different with dipotassium tetramethyl osmate staining, particularly the outer cell walls of fungi. Indications of specific precipitate-producing reactions in cell storage areas are observed.

Cell Wall↗
PubMed1974

Morphological observations of Diplodia maydis on synthetic and natural substrates as revealed by scanning electron microscopy.

Mycelial and spore morphology of Diplodia maydis were investigated by using scanning electron microscopy after growth on various media and natural substrates (oat and corn kernels, and corn husks). Of several specimen preparation methods studied, Parducz fixation followed by critical-point or freeze-drying gave adequate preservation for pycnidia, mycelia, and spores. Morphological characteristics were similar in rotary and reciprocal shaker cultures and differed from that found in stationary cultures in the amount of slime-like material produced and precipitated matter on the mycelial surfaces. In general, mycelial surfaces were smooth. Large areas of coalesced material were present in all samples examined. Slime-like material produced in liquid media appeared as a finely laced net, randomly appearing throughout the mycelia with bead-like structures present along the net. A fine netting also was observed interspersed among the spores inside the pycnidia obtained from oats. Slime-like material was observed to cover the pycnidia produced on oat and corn kernels. In the latter case, the spores were less protected by the outer slime-like covering. Thickened node-like structures were observed in mycelial mats produced in modified Fries 2 medium, on potato dextrose agar plates, and on infected oats. Round and ovate thickened node-like structures were observed in mycelium produced on corn kernels. In general, node-like structures were less abundant in mycelia from naturally infected substrates. Conidia were commonly rounded to tapered and two celled, with a distinctive ridged septum at the middle. Dried spores were collapsed in a characteristic flask-like fashion.

Culture Media↗
PubMed1969

Surface features of Bacillus polymyxa spores as revealed by scanning electron microscopy.

The surface features of Bacillus polymyxa spores were compared by use of thin sections, carbon replicas, and the scanning electron microscope. Some features of the characteristic ridges, previously reported in ultrathin sections and carbon replicas of spores of this species, were more clearly revealed with the scanning electron microscope. A three-dimensional image is provided because of the greater depth of focus possible with this instrument. End-on views of B. polymyxa spores readily illustrate the polygonal porelike structure present.

Bacillus↗
PubMedDate not supplied

Hemodynamic stability during arteriovenous carbon dioxide removal for adult respiratory distress syndrome: a prospective randomized outcomes study in adult sheep.

To evaluate the ability of arteriovenous carbon dioxide removal (AVCO2R) to maintain hemodynamic stability during treatment of adult respiratory distress syndrome (ARDS), we used our smoke/burn, LD40 sheep model of ARDS. With onset of ARDS (PaO2/FiO2 < 200) animals were randomized to AVCO2R (n = 20) or SHAM (n = 8). With AVCO2R, the carotid artery (10-14 F) and jugular vein (14-16 F) were cannulated; SHAM received identical management, sparing the vessels. AVCO2R maintained stable hemodynamics compared to SHAM at 48 hours; heart rate (114.8+/-6.1 vs. 110.1+/-11.0 beats/min.), mean arterial pressure (112+/-5.1 vs. 107.0+/-8.5 mm Hg), cardiac output (7.4+/-0.5 vs. 7.5+/-0.9 L/min.), pulmonary arterial pressure (26+/-2.4 vs. 21+/-1.3 mm Hg), pulmonary arterial wedge pressure (14.1+/-1.8 vs. 14.0+/-1.2 mm Hg), and central venous pressure (7+/-1.6 vs. 8+/-0.9 mm Hg). At 48 hours, AVCO2R allowed significant reductions (p<0.05) in minute ventilation (13.6+/-2.5 to 7.6+/-0.8 L/min); tidal volume (TV) (389.4+/-24.1 to 295.0+/-10.1 ml); peak inspiratory pressure (PIP) (25.4+/-9.2 to 18.8+/-2.5 cm H2O); RR (27.5+/-0.7 to 21.6+/-1.8 breaths/min); and FiO2 (0.96+/-0.00 to 0.48+/-0.2) while normocapnia was maintained. AVCO2R is an effective method of CO2 removal during severe respiratory failure that is hemodynamically well tolerated.

Age Factors↗
PubMedDate not supplied

Self-monitoring of capillary blood glucose: changing the performance of individuals with diabetes.

Standard reflectance meters were modified by the addition of memory chips capable of storing 440 glucose determinations with corresponding time and date. These modified reflectance meters (MR) were given to 20 individuals with type I diabetes in an effort to determine the level of reliability and accuracy they could achieve on a self-monitoring regimen. During a 6-wk period these subjects measured their capillary blood glucose and recorded the results in a logbook (LB). At 2-wk intervals they visited the clinic. Data from the MR was offloaded onto an Apple IIe microcomputer (Apple Computer, Inc., Cupertino, California) and presented to the subjects in a graphic format, depicting the level of metabolic control over the previous 2 wk. The performance of subjects for the 6-wk period showed that they averaged 7 omissions from the LB for every 100 MR recordings; 1 added value in the LB for every 200 MR recordings; and 1 error in accurately copying the test value for every 100 determinations. In comparison with subjects who participated in an earlier study in which they were unaware of the memory function of the reflectance meter, performance during the current study improved in all categories. It was also observed that consistency in reliable and accurate record keeping did not diminish throughout the study period. Despite these positive changes in performance, no alteration in glycemic control was found.

Adolescent↗
PubMedDate not supplied

Inflammatory cell responses to radial keratotomy.

Radial keratotomy stimulates the influx of polymorphonuclear cells (PMNs) into the tear film and stroma. These cells do not degranulate and are gone in four days. Incisions fill with persistent epithelial plugs, and extracellular matrix (ECM) replacement does not occur. In contrast, a thermal burn stimulates a prolonged influx of PMNs into the tear film and stroma, where they degranulate and remove damaged tissue. ECM replacement in a few weeks suggests that factors released by activated PMNs may stimulate normal wound healing in the cornea.

Animals↗