Biomedical subjects

J M Robinson

Publications and source records attributed to J M Robinson.

At least 127 records · Page 7Linked to original sources

PubMed1986

Retinoids stimulate the release of superoxide by neutrophils and change their morphology.

All-trans-retinal stimulated the release of superoxide by human and guinea pig neutrophils 63 +/- 14 SD and 53 +/- 5 SD nmol of O2-/min/10(7) cells, respectively. Superoxide release by unstimulated cells was negligible. All-trans-retinal also induced morphological changes (i.e., evaginations) in these cells. Other retinoids were effective in instigating these phenomena. The similarities of these effects to those instigated by cis-unsaturated fatty acids (Badwey, J.A., et al., 1984, J. Biol. Chem., 259:7870-7877) are discussed in light of possible mechanisms.

Animals↗

PubMed1986

Superoxide production by polymorphonuclear leukocytes. A cytochemical approach.

Phagocytosis by polymorphonuclear leukocytes triggers a burst of oxidative metabolism resulting in hydrogen peroxide and superoxide production, and these active oxygen species function in the killing of microorganisms. A new cytochemical technique, based on a manganese dependent diaminobenzidine oxidation, has been developed to detect superoxide in these cells. It has been shown that superoxide generation is associated with the plasma membrane in cells activated by particulate (zymosan) and non-particulate (phorbol myristate acetate) stimuli. This membrane activity is maintained during invagination such that reduced oxygen is generated within the endocytic vacuoles. Reaction product is absent from unstimulated cells; additionally, formation of precipitate is blocked by omission of Mn++, low temperature, glutaraldehyde prefixation, and the presence of superoxide dismutase in the incubation medium.

3,3'-Diaminobenzidine↗

PubMed1986

Cytochemical localization of acid phosphatase in striated muscle.

Normal skeletal and cardiac striated muscle from adult rats was incubated for the cytochemical detection of acid phosphatase activity with cerium as the capture metal. Results from these experiments show that normal striated muscle has a greater number of acid phosphatase-positive structures, which are presumed to be lysosomes, than has been indicated by several previous cytochemical studies.

Acid Phosphatase↗

PubMed1986

Selective low-dose streptokinase infusion in the treatment of acute transplant renal vein thrombosis.

A renal transplant recipient developed acute renal transplant vein thrombosis following surgery for a total hip replacement. As an alternative to standard surgical therapy, the patient was treated with selective intravenous low-dose infusion of streptokinase at doses of 5,000-20,000 units/h. The infusion was continued for 120 h with constant monitoring of PT, PTT, and fibrinogen levels. Therapy resulted in excellent preservation of renal function without complications. Low-dose selective infusion of streptokinase should be considered a potential alternative therapy for acute transplant renal vein thrombosis.

Acute Disease↗

PubMed1986

Unusual lysosomes in aortic smooth muscle cells: presence in living and rapidly frozen cells.

Unusual tubular structures have been observed in rat aortic smooth muscle cells (SMC) grown in culture. These tubular structures have several characteristics that strongly suggest that they are lysosomes: they are bounded by a single membrane bilayer, contain densely staining material, and acid phosphatase activity. Furthermore, these structures are present in living cells, as demonstrated by their ability to accumulate the membrane-impermeable fluorescent dye lucifer yellow CH. In ultrastructural preparations they are best seen in samples that are cryofixed by rapid freezing and then freeze-substituted in osmium-acetone solutions. Conventional chemical fixation did not appear to preserve these structures to as great an extent as did rapid freezing. Comparison of SMC in vitro to the same cells in situ revealed differences in lysosome number as well as morphological appearance. Thus, the culturing of rat SMC leads to the formation of unusual tubular lysosomes whose ultrastructural appearance is particularly sensitive to the methods employed for examination.

Acid Phosphatase↗

PubMed1986

Carbon dioxide and nitrite photoassimilatory processes do not intercompete for reducing equivalents in spinach and soybean leaf chloroplasts.

Previously, C Baysdorfer and JM Robinson (1985 Plant Physiol 77: 318-320) demonstrated that, in a reconstituted spinach chloroplast system, NADP photoreduction functioning at most maximal rate and reductant demand, was the successful competitor with NO(2) (-) photoreduction for reduced ferredoxin. This resulted in a repression of NO(2) (-) reduction until all NADP available had been almost totally reduced. Further experiments, employing isolated, intact spinach leaf plastids and soybean leaf mesophyll cells, were conducted to examine competition for reductant between CO(2) and NO(2) (-) photoassimilation, in situ. In isolated, intact plastid preparations, regardless of whether the demand for reductant by CO(2) photoassimilation was high (5 millimolar ;CO(2)') with rates of CO(2) fixation in the range 40 to 90 micromoles CO(2) fixed per hour per milligram chlorophyll, low (0.5 millimolar ;CO(2)') with rates in the range 5 to 8 micromoles CO(2) per hour per milligram chlorophyll, or zero (no ;CO(2)'), NO(2) (-) photoreduction displayed equal rates in the range of 8 to 22 micromoles per hour per milligram chlorophyll. In the absence of ;CO(2)', but in the presence of saturating white light, 3-phosphoglycerate photoreduction at rates of 82 to 127 micromoles per hour per milligram chlorophyll did not repress, and occasionally stimulated concomitant rates of NO(2) (-) reduction which ranged from 23.4 to 38.5. Conversely, in plastid preparations, NO(2) (-) at levels of 50 to 100 micromolar, stimulated plastid CO(2) fixation when ;CO(2)' was saturating with respect to carboxylation. Further, levels of NO(2) (-) in the range 250 to 2500 micromolar, stimulated soybean leaf mesophyll cell net CO(2) fixation as much as 1.5-fold if ;CO(2)' was saturating with respect to CO(2) fixation. It appeared likely that, in high light in vivo, CO(2) and NO(2) (-) photoassimilatory processes are not forced to intercompete for reduced ferredoxin in the intact chloroplast.

Journal Article↗

PubMed1986

Hypotensive anaesthesia for microsurgery of the middle ear. A comparison between isoflurane and halothane.

Fifty patients undergoing microsurgery of the ear were anaesthetised using thiopentone, nitrous oxide, oxygen and either halothane or isoflurane, via a low flow circle system with carbon dioxide absorption. Systolic blood pressure was reduced to approximately 70 mmHg by the additional use of increments of labetalol; the patients breathed spontaneously. The degree of haemostasis was assessed by the surgeon who was unaware which volatile agent was being used to supplement anaesthesia. Isoflurane, although it is a potent vasodilator produced operating conditions which were indistinguishable from halothane. Isoflurane is thus a safe and reliable alternative to halothane as a volatile agent used to supplement anaesthesia when using induced hypotension for middle ear surgery.

Adolescent↗

PubMed1986

Dietary cholesterol-induced changes in macrophage characteristics. Relationship to atherosclerosis.

In diet-induced hypercholesterolemia, circulating monocytes adhere to the endothelium of the vessel wall and emigrate into the intima. Atherosclerotic lesions may develop, characterized by the presence of lipid-laden macrophages and proliferating smooth muscle cells recruited from the media. Using rat peritoneal macrophages, the authors examined the influence of diet-induced hypercholesterolemia on several variables of macrophage function that may contribute to lesion formation, including adhesion to bovine aortic endothelial cells (BAECs) and vascular smooth muscle cells (VSMCs), the production of chemoattractants and mitogens for VSMCs, and the release of the reactive oxygen species, superoxide. In general, a hypercholesterolemia-induced augmentation of macrophage function was observed. In comparison with macrophages from normal animals (N M phi s), macrophages from hypercholesterolemic animals (H M phi s) were 50-80% more adhesive to BAECs and VSMCs. H M phi-secreted products increased VSMC migration 6 to 7-fold, whereas N M0s only stimulated motility 2.5-fold. In addition, H M phi-conditioned media produced increased VSMC growth 5-fold, compared with a 2.5-fold increase produced by N M phi-conditioned media. Although the production of superoxide was found to be the same for both N M phi s and H M phi s, the release of superoxide by macrophages found in the intima of hypercholesterolemic animals may contribute to the necrosis of cells in the developing lesion. These results suggest that dietary cholesterol may accelerate atherosclerotic lesion formation by inducing specific changes in the properties of circulating monocytes and intimal macrophages.

Animals↗

PubMed1986

Gossypol-induced damage to mitochondria of transformed Sertoli cells.

Studies on gossypol-induced morphologic changes in transformed Sertoli cells (TM4) were performed at both light- and electron-microscopic levels. Exposure of TM4 cells to 5 micrograms gossypol/ml for greater than 1 hour has severe, deleterious effects on the structure and function of mitochondria. Mitochondrial function in TM4 cells was monitored by employing a fluorochrome, Rhodamine 123, which accumulates rapidly in mitochondria having a high transmembrane potential. In gossypol-treated TM4 cells, Rhodamine 123 mitochondrial staining was reduced significantly 1 hour after the drug addition and reached a minimal level at 3 hour. Concomitantly, cytoplasmic vacuoles were detected even at the light-microscopic level. Electron-microscopic studies revealed that these vacuoles were distended mitochondria. The morphology of these damaged organelles changed gradually, starting with the transformation of the tubular mitochondria into the rounded forms. Cristae concurrently collapsed onto the organelles' periphery. In addition, the ground matrixes disappeared, and the mitochondria appeared as empty vacuoles. Further evidence that these vacuoles were distended mitochondria was derived from the cytochemical localization of cytochrome c oxidase in these vacuole-like structures.

Animals↗

PubMed1985

Pharyngoesophageal reconstruction. Is a skin-lined pharynx necessary?

Current methods of pharyngoesophageal reconstruction have in common the creation of an epithelial lined pharynx. We performed eight cases of pharyngoesophageal reconstruction with a pectoralis major muscle flap. In the first six cases, split-thickness skin was quilted onto the muscle. In the last two cases, pectoralis major muscle alone was used, allowing epithelialization to occur from adjacent mucosa. The results with this simplified technique have been as good as when a skin-grafted muscle flap was used. We prefer a pectoralis major muscle flap, with or without split-thickness skin, to a pectoralis myocutaneous flap. There is no hair growth, it is easy to tube, and a thin-walled pharynx is produced. This is an advantage for the development of an esophageal voice, and tracheoesophageal puncture can be easily performed if no voice is achieved. All of our patients received full-dose, preoperative radiotherapy. One patient developed a fistula that closed spontaneously. There have been no strictures at the pharyngoesophageal junction. All patients quickly established a good oral intake.

Aged↗

PubMed1985

Triton X-100 extraction of P815 tumor cells: evidence for a plasma membrane skeleton structure.

It has been shown that a Triton X-100-insoluble protein matrix can be isolated from the plasma membranes of P815 tumor cells and murine lymphoid cells (Mescher, M. F., M. J. L. Jose and S. P. Balk, 1981, Nature (Lond.), 289:139-144). The properties of the matrix suggested that this set of proteins might form a membrane skeletal structure, stable in the absence of the lipid bilayer. Since purification of plasma membrane results in yields of only 20 to 40%, it was not clear whether the matrix was associated with the entire plasma membrane. To determine if a detergent-insoluble structure was present over the entire cell periphery and stable in the absence of the membrane bilayer or cytoskeletal components, we have examined extraction of whole cells with Triton X-100. Using the same conditions as those used for isolation of the matrix from membranes, we found that extraction of intact cells resulted in structures consisting of a continuous layer of protein at the periphery, a largely empty cytoplasmic space, and a nuclear remnant. Little or no lipid bilayer structure was evident in association with the peripheral layer, and no filamentous cytoskeletal structures could be seen in the cytoplasmic space by thin-section electron microscopy. Analysis of these Triton shells showed them to retain approximately 15% of the total cell protein, most of which was accounted for by low molecular weight nuclear proteins. 5'-Nucleotidase, a cell surface enzyme that remains associated with the plasma membrane matrix, was quantitatively recovered with the shells. Included among the polypeptides present in the shells was a set with mobilities identical to those of the set that makes up the plasma membrane matrix. The polypeptide composition of the shells further confirmed that cytoskeletal proteins were present to a very low extent, if at all, after the extraction. The results demonstrate that a detergent-insoluble protein matrix associated with the periphery of these cells forms a continuous, intact macrostructure whose stability is independent of the membrane bilayer or filamentous cytoskeletal elements, and thus has the properties of a membrane skeletal structure. Although not yet directly demonstrated, the results also strongly suggest that this peripheral layer is composed of the previously described set of plasma membrane matrix proteins. This article discusses possible roles for this proposed membrane skeletal structure in stabilizing the membrane bilayer and affecting the dynamics of other membrane proteins.

Animals↗

PubMed1985

Release of superoxide and change in morphology by neutrophils in response to phorbol esters: antagonism by inhibitors of calcium-binding proteins.

The ability of phorbol derivatives to function as stimulating agents for superoxide (O2-) release by guinea pig neutrophils has been evaluated and compared to the known ability of each compound to activate protein kinase C. Those that activate the kinase also stimulate O2- release, while those that are inactive with respect to the kinase have no effect on O2- release. The same correlation was observed with respect to the ability of phorbol esters to induce morphological changes in neutrophils, i.e., vesiculation and reduction in granule content. Certain phenothiazines and naphthalene sulfonamides that are known antagonists of calcium-binding proteins blocked both phorbol ester-induced O2- release and morphological changes in these cells.

Animals↗

PubMed1985

Metabolic Interactions between Spinach Leaf Nitrite Reductase and Ferredoxin-NADP Reductase: Competition for Reduced Ferredoxin.

Steady state rates of NADP reduction decline upon commencement of nitrite reduction in reconstituted chloroplast preparations. Similarly, steady state rates of nitrite reduction are lower, but not zero, during concurrent NADP reduction. These results imply that competition for substrate occurs and suggest that nitrite reduction can successfully compete for reduced ferredoxin, even at high rates of NADP reduction.

Journal Article↗

PubMed1985

Isolation of mitochondria from soybean leaves on discontinuous percoll gradients.

A technique to isolate mitochondria from chamber-grown soybeans (Glycine max cv Williams) was developed. The mitochondria were isolated by centrifugation on discontinuous Percoll gradients which yielded a sharp band of mitochondria contaminated by only 4% of the total chlorophyll in the gradient. Contamination by peroxisomes was also slight. The isolated mitochondria oxidized malate plus glutamate, NADH, and malate with respiratory control. They also showed cyanide-insensitive, alternative pathway activity which was inhibited by salicylhydroxamic acid.

Journal Article↗

PubMed1985

Effects of CO(2) Enrichment and Carbohydrate Content on the Dark Respiration of Soybeans.

During the period of most active leaf expansion, the foliar dark respiration rate of soybeans (Glycine max cv Williams), grown for 2 weeks in 1000 microliters CO(2) per liter air, was 1.45 milligrams CO(2) evolved per hour leaf density thickness, and this was twice the rate displayed by leaves of control plants (350 microliters CO(2) per liter air). There was a higher foliar nonstructural carbohydrate level (e.g. sucrose and starch) in the CO(2) enriched compared with CO(2) normal plants. For example, leaves of enriched plants displayed levels of nonstructural carbohydrate equivalent to 174 milligrams glucose per gram dry weight compared to the 84 milligrams glucose per gram dry weight found in control plant leaves. As the leaves of CO(2) enriched plants approached full expansion, both the foliar respiration rate and carbohydrate content of the CO(2) enriched leaves decreased until they were equivalent with those same parameters in the leaves of control plants. A strong positive correlation between respiration rate and carbohydrate content was seen in high CO(2) adapted plants, but not in the control plants.Mitochondria, isolated simultaneously from the leaves of CO(2) enriched and control plants, showed no difference in NADH or malate-glutamate dependent O(2) uptake, and there were no observed differences in the specific activities of NAD(+) linked isocitrate dehydrogenase and cytochrome c oxidase. Since the mitochondrial O(2) uptake and total enzyme activities were not greater in young enriched leaves, the increase in leaf respiration rate was not caused by metabolic adaptations in the leaf mitochondria as a response to long term CO(2) enrichment. It was concluded, that the higher respiration rate in the enriched plant's foliage was attributable, in part, to a higher carbohydrate status.

Journal Article↗

PubMed1985

Sucrose and Starch Synthesis in Spinach Plants Grown under Long and Short Photosynthetic Periods.

The flow of carbon into sucrose and starch was investigated in fully expanded primary leaves of spinach using the long to short day transition and partial defoliation as tools to manipulate sucrose/starch synthesis. Transfer from 12 hour to 7 hour photosynthetic periods resulted in a 4-fold increase in the initial rate of starch synthesis, a 50% increase in the initial rate of sucrose synthesis, a 30% increase in leaf sucrose, and a 40% decrease in fructose, 2,6-biphosphate. In addition, sucrose synthesis rates in cells isolated from shortened daylength plants are 80% higher than in cells isolated from control plants. These results show that, in spinach, an increase in the rates of both sucrose and starch synthesis can occur under short day conditions. In contrast, when short day plants are partially defoliated, starch levels remain high, fructose 2,6-biphosphate levels remain low, but the level of leaf sucrose drops by 50%. Thus, when demand exceeds supply, starch synthesis has priority over filling of leaf sucrose pools in the short day plant.

Journal Article↗

PubMed1985

A Rapid Increase in Spinach Leaf Fructose 2,6-Bisphosphate Occurs during a Light to Dark Transition.

Spinach leaf fructose 2,6-bisphosphate levels increase rapidly during the first 15 minutes of a normal dark period followed by a gradual decline during the next 5 hours. The regulatory mechanism responsible for the dark-induced rise in fructose 2,6-bisphosphate levels can be counteracted by a brief exposure to light intensities greater than 1 microeinstein per square meter per second.

Journal Article↗

PubMed1985

Improved localization of intracellular sites of phosphatases using cerium and cell permeabilization.

A simple permeabilization method has been developed that allows for intracellular localization of acid phosphatase in neutrophils and several types of tissue culture cells with cerium. This permeabilization procedure also facilitates intracellular alkaline phosphatase localization in neutrophils without the loss of cell surface reaction in this cell type. Only the cell surface reaction was detected in the absence of permeabilization. Glutaraldehyde-fixed cells were permeabilized with detergent during the cytochemical reaction. Triton X-100 at 0.0001-0.0002% gave the best results for the enzymes and cell types tested.

Acid Phosphatase↗