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Biomedical subjects

M E Sloan

Publications and source records attributed to M E Sloan.

10 recordsLinked to original sources
PubMed1989

Infectious mononucleosis with acute thrombocytopenia.

Three cases of severe acute thrombocytopenia complicating infectious mononucleosis are described. Although spontaneous remission may be a feature of this rare complication, in each of these cases steroid therapy resulted in a rapid rise in the platelet count.

Adolescent↗
PubMed1989

Susceptibility of UDP-Glucose:(1,3)-beta-Glucan Synthase to Inactivation by Phospholipases and Trypsin.

UDP-glucose:(1,3)-beta-glucan synthase from Beta vulgaris L. was rapidly inactivated by treatment with phospholipases C, D, and A(2). Enzyme activity could not be restored to the phospholipase-treated enzyme by the addition of phosphatidylethanolamine or other phospholipids. Membrane-bound and solubilized glucan synthase were also trypsin-labile with inactivation rates equal in the presence or absence of divalent cations or chelators. Gradual activity declines were observed in membranes incubated with divalent cations, but not with chelators.

Journal Article↗
PubMed1989

UDP-Glucose: (1,3)-beta-Glucan Synthase from Daucus carota L. : Characterization, Photoaffinity Labeling, and Solubilization.

The membrane-bound UDP-glucose-beta-(1,3)-glucan synthase from Daucus carota L. was characterized and a solubilization procedure was developed. The enzyme exhibited maximal activity in the presence of 0.75 millimolar Ca(2+), 0.5 millimolar EGTA, and 5 millimolar cellobiose at pH 7.5 and 30 degrees C at 1 millimolar UDPG. Reaction products were confirmed to be (1,3)-linked glucan. Polypeptides of 150, 57, and 43 kilodaltons were labeled with the photoactivatible affinity label 5-azido-uridine 5'-beta-[(32)P] diphosphateglucose. Labeling of the 150 and 57 kilodalton polypeptides was completely protected against by 1 millimolar non-radioactive UDPG suggesting that one or both of these polypeptides may represent the UDPG binding subunit of glucan synthase. Carrot glucan synthase was solubilized with the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS) in the absence of divalent cations and chelators; however, the percentage of enzyme which could be solubilized showed variability with membrane source. With microsomal membranes, up to 80% of the enzyme was released with 0.7% CHAPS. Solubilized enzyme was stable for at least 9 hours at 4 degrees C. When more highly purified membrane fractions were isolated from sucrose step gradients a slightly different picture emerged. Activity from the 20/30% interface (Golgi and tonoplast enriched) was readily solubilized and expressed. Activity from the 30/40% interface (plasma membrane enriched) was also solubilized; however, it was necessary to add heat inactivated microsomes to assay mixtures for full activity to be expressed. A requirement for endogenous activators is suggested.

Journal Article↗
PubMed1987

CHAPS Solubilization and Functional Reconstitution of beta-Glucan Synthase from Red Beet Root (Beta vulgaris L.) Storage Tissue.

A method for the solubilization and reconstitution of red beet (1,3)-beta-d-glucan synthase with the detergent 3-[(3-cholamidopropyl) dimethylammonio]-1-propane sulfonate (CHAPS) was developed. Glucan synthase was effectively solubilized from microsomal or plasma membranes by 0.6% CHAPS in the presence of EGTA and EDTA. Chelators were found essential for effective solubilization and divalent cations inhibitory. A preextraction of membranes with 0.3% CHAPS and 5 millimolar Mg(2+) prior to the solubilization step was found to remove protein contaminants and increase the specific activity of the solubilized enzyme. Conditions for recovering activity from Sepharose 4B gel filtration columns were defined. Addition of phospholipids and low levels of CHAPS in column elution buffers resulted in complete functional reconstitution with 100% recovery of added activity. Specific activities were increased 20- to 22-fold over microsomes. Active vesicles were recovered by centrifugation. These results provide independent and direct confirmation of the enzyme's requirement for a phospholipid environment.

Journal Article↗
PubMed1986

Compensation point and isotopic characteristics of c(3)/c(4) intermediates and hybrids in panicum.

Leaf CO(2) compensation points and stable hydrogen, oxygen and carbon isotope ratios were determined for Panicum species including C(3)/C(4) intermediate photosynthesis plants, hybrids between C(3)/C(4) intermediates and C(3) plants, C(3) and C(4) plants in the Panicum genus as well as several other C(3) and C(4) plants. C(3) plants had the highest compensation points, followed by hybrids, C(3)/C(4) intermediates, and C(4) plants. delta(13)C values of cellulose nitrate and saponifiable lipids from C(4) plants were about 10 per thousand higher than those observed for cellulose nitrate and saponifiable lipids of C(3)/C(4) intermediates, hybrids, and C(3) plants. Oxygen isotope ratios of cellulose as well as those of leaf water were similar for all plants. There was substantial variability in the deltaD values of cellulose nitrate among the plants studied. In contrast, such variability was not observed in deltaD values of water distilled from the leaves, nor in the deltaD values of the saponifiable lipids. Variability in deltaD values of cellulose nitrate from C(3)/C(4) intermediates, hybrids, C(3), and C(4) plants is due to fractionations occurring during biochemical reactions specific to leaf carbohydrate metabolism.

Journal Article↗
PubMed1986

Training respite care providers for families with handicapped children: Experimental analysis and validation of an instructional package.

We conducted four experiments to evaluate a respite care training package. In Experiment 1, we assessed the effectiveness of an instructional manual on the acquisition of respite care skills and compared the relative effects of three different manual on the acquisition of respite care skills and compared the relative effects of three different manual presentation formats. Results showed that performance during simulated (role-played) respite care situations improved substantially for all six trainees following presentation of the instructional manual (with no significant differences between presentation formats) although some remedial training was necessary to achieve mastery criterion. In Experiment 2, we evaluated the effects of the manual presented as a whole with a larger group of trainees and compared it to a workshop training approach. Results showed that both the instructional manual and workshop training approaches were effective, but that the former appeared to be more cost-effective. In both experiments, correct responding generalized to a respite care situation with a multiply handicapped child. In addition, several measures of social validity were obtained. In Experiment 3, we evaluated a simplified training and assessment package that could be conducted using the resources typically available to respite care agencies, and in Experiment 4, we demonstrated that respite care agency personnel could successfully implement this program.

Journal Article↗
PubMed1979

Ruptured hepatic aneurysm in systemic lupus erythematosus.

We report on a patient with systemic lupus erythematosus (SLE) who suffered catastrophic haemorrhage following rupture of an intrahepatic aneurysm. The association between hepatic artery aneurysm and SLE has not been recorded previously, but we have found evidence from the literature that there may be an association between autoagressive disorders and this surgical emergency.

Adult↗