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Biomedical subjects

M C Smith

Publications and source records attributed to M C Smith.

At least 307 records · Page 17Linked to original sources
PubMed1982

Neutrophil adhesiveness during prostacyclin and heparin hemodialysis.

We evaluated neutrophil adhesive function in patients undergoing chronic hemodialysis using either prostacyclin or heparin as antithrombotic agents. Patients underwent successive hemodialyses with prostacyclin (4 ng/kg/min) and heparin. There were no significant differences noted in neutrophil adhesive function during either dialysis: transient neutropenia developed in each case; impaired neutrophil adhesiveness to plastic developed during both dialyses; neutrophil aggregation was diminished when compared to predialysis responses during both dialyses. Furthermore, the number of circulating Fc-receptor-bearing neutrophils fell significantly during both prostacyclin and heparin hemodialysis. Our study demonstrates that substitution of prostacyclin for heparin in doses that do not cause hypotension, does not prevent neutropenia or alter the diminished neutrophil adhesiveness that occurs during heparin hemodialysis.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

Evaluation of an automated radioimmunoassay system: the ARIA II.

The ARIA II is an automated instrument for the quantitation by radioimmunoassay of the following constituents: digoxin, cortisol, thyroxine, T3 uptake, T3 RIA, estriol, and progesterone, its methodology uses a specific antibody covalently bonded to a solid support in a reusable antibody chamber. We evaluated the assay system for the first three constituents listed above. Coefficients of correlation with conventional manual methods were: thyroxine-0.9797; digoxin-0.9871; and cortisol-0.9727. Inter-assay variations using a commercially available tri-level control serum were as follows: thyroxine-5.4 to 10.3%; digoxin-3.7 to 6.3%; cortisol-5.2 to 8.4%. The ARIA II is not a discrete analyzer, and an estimate of carryover was significant only on low-to-high for the thyroxine assay. ARIA II assays are approximately one-half the cost of manual assays. Time studies indicate the ARIA II to be most suited to laboratories of low or moderate volume.

Autoanalysis↗
PubMed1981

Acute hemolytic anemia, methemoglobinemia, and heinz body formation associated with ingestion of red maple leaves by horses.

From June 1975 through June 1979, acute hemolytic anemia developed in 11 horses from 7 New York farms. Of the 7 horses that died, 6 had methemoglobinemia. In the 4 horses that recovered, methemoglobinemia was not observed. but Heinz body formation was seen in 3 of the 4. On 2 of the premises involved, frank methemoglobinemia was observed concurrently with Heinz body formation, suggesting a relationship between the pathogenesis of methemoglobinemia and Heinz body formation in the hemolytic process. In addition to the 11 cases described, 22 clinically similar cases were reported to us during the period of this investigation by practicing veterinarians from New York, Pennsylvania, and the New England states. All 33 cases of hemolytic anemia occurred between June and October of each year, and affected horses had access to outside paddocks or fields containing a variety of native grasses, weeds, and trees. On 2 farms, hemolytic anemia developed after the horses were observed browsing fallen branches of red maple trees (Acer rubrum). Red maple leaves and bark were obtained from 1 of these farms, and approximately 1 kg of a leaf and bark mixture was fed to each of 2 ponies. Within 48 hours, both ponies became ill. The syndrome was indistinguishable from that observed in clinical patients and was characterized by methemoglobinemia and intravascular hemolysis. The ponies died 5 and 6 days after which time the packed cell volumes were 6% and 7% respectively. It was concluded that many cases of hemolytic anemia in horses in northeastern states may be related to ingestion of leaves or bark from red maple trees. The studies did not, however, define the factors that predispose to poisoning and did not exclude the possibility that other environmental toxins may have been involved.

Acute Disease↗
PubMed1981

The clinical spectrum of renal cholesterol embolization.

Renal cholesterol embolization can occur spontaneously or as a complication of aortic surgery or major vessel angiography in patients with diffuse atherosclerosis. The demonstration of characteristic cholesterol crystals in tissue biopsy specimens is a pathognomonic finding. However, renal cholesterol embolism may be clinically diagnosed when renal failure develops after known inciting factors or together with systemic manifestations of atheromatous embolization such as lower extremity livedo reticularis, focal digital ischemia or retinal embolism. Previous investigators have emphasized the progressive nature of renal insufficiency due to cholesterol embolism, its poor prognostic significance and almost uniformly fatal outcome. In this report, we describe five additional patients with renal cholesterol embolization. In three of them only moderate renal insufficiency developed, and kidney function subsequently improved in all. In two patients the condition progressed to end-stage renal disease; one died with chronic renal failure whereas the other patient required four months of hemodialysis before kidney function eventually improved. Thus, cholesterol embolization may produce a spectrum of renal functional impairment. In some patients there is only a moderate loss of renal function with subsequent improvement; in others renal failure ensues. In this latter group, eventual return of kidney function can occur even after a prolonged period of renal insufficiency.

Aged↗
PubMed1981

The persistence and disappearance by washoff and dryfall of methoxychlor from soybean foliage--a preliminary study.

The persistence and disappearance (washoff or dryfall) of methoxychlor [2,2-bis(p-methoxyphenyl)-1,1,1-trichloroethane] from mature soybean [Glycine max (L.) Merrill] foliage was investigated in a small field plot study under natural rainfall conditions in 1977 and 1978. Residue analyses were conducted using whole plant samples. Methoxychlor washoff rate was 8+/- 4% of the amount on plants (prior to rain) per centimeter of rainfall, regardless of time after application. Total seasonal washoff for 1978 accounted for 33.5% of the applied pesticide; however, 30.5% of the total loss was removed by washoff on the second day after application. Dryfall or dislodgeable residue accounted for less than 1% of the amount applied. The amount of dryfall was significantly greater in plots entered by workers than in those where entry was avoided. More than 19% of the applied methoxychlor was lost as a result of through-fall to the ground during application to the plots. Statistical analyses indicated that within-sample variation for mechanical chopping of plant samples was significantly smaller at the 5% level than for a hand chopping method. Results from this study will be useful in defining research objectives for the development of algorithms to describe the behavior of foliar-applied compounds. Such algorithms are necessary for estimating runoff losses of insecticides to water bodies.

Methoxychlor↗
PubMed1981

Impaired platelet thromboxane production in renal failure.

Platelet aggregation and thromboxane B2 production, in response to adenosine diphosphate, were significantly impaired in 7 undialyzed or inadequately dialyzed patients with renal failure when compared to adequately dialyzed individuals or normal subjects. In 1 patient, platelet aggregation and thromboxane synthesis were corrected after adequate hemodialysis. The defect in both platelet aggregation and thromboxane production was induced in normal platelets incubated with uremic platelet-poor plasma. These findings suggest that the uremic platelet defect may be due, in part, to a plasma factor that inhibitors platelet thromboxane synthesis. Further, adequate dialytic therapy may reverse this defect.

Acute Kidney Injury↗
PubMed1981

Deafness in adults-screening in general practice.

A random sample of 1,083 people, drawn from the lists of two practices in Leeds, was used to estimate the prevalence of deafness among adults. A test for deafness (defined as failure to hear 35 decibels at 1000 Hz in one or both ears) using a portable audiometer proved simple to operate with little observer variation. Eight per cent of adults were found to be deaf. The prevalence of deafness increased with age and was lowest in social classes I and II; there was no significant difference between the sexes. Audiometry showed that 17 per cent of those who thought their hearing was abnormal had no recorded loss of hearing using the stated test and that 18 per cent of those who are deaf would be overlooked if the question "Do you think your hearing is normal?" was used for initial screening in general practice. Less than 20 per cent knew of any services or aids for the deaf apart from those available through general practitioners.

Adolescent↗
PubMed1980

Tracing the time course of picture--word processing.

A number of independent lines of research have suggested that semantic and articulatory information become available differentially from pictures and words. The first of the experiments reported here sought to clarify the time course by which information about pictures and words becomes available by considering the pattern of interference generated when incongruent pictures and words are presented simultaneously in a Stroop-like situation. Previous investigators report that picture naming is easily disrupted by the presence of a distracting word but that word naming is relatively immune to interference from an incongruent picture. Under the assumption that information available from a completed process may disrupt an ongoing process, these results suggest that words access articulatory information more rapidly than do pictures. Experiment 1 extended this paradigm by requiring subjects to verify the category of the target stimulus. In accordance with the hypothesis that picture access the semantic code more rapidly than words, there was a reversal in the interference pattern: Word categorization suffered considerable disruption, whereas picture categorization was minimally affected by the presence of an incongruent word. Experiment 2 sought to further test the hypothesis that access to semantic and articulatory codes is different for pictures and words by examining memory for those items following naming or categorization. Categorized words were better recognized than named words, whereas the reverse was true for pictures, a result which suggests that picture naming involves more extensive processing than picture categorization. Experiment 3 replicated this result under conditions in which viewing time was held constant. The last experiment extended the investigation of memory differences to a situation in which subjects were required to generate the superordinate category name. Here, memory for categorized pictures was as good as memory for named pictures. Category generation also influenced memory for words, memory performance being superior to that following a yes--no verification of category membership. These experiments suggest a model of information access whereby pictures access semantic information were readily than name information, with the reverse being true for words. Memory for both pictures and words was a function of the amount of processing required to access a particular type of information as well as the extent of response differentiation necessitated by the task.

Form Perception↗
PubMed1980

Thermodynamic technique for the quantification of regional blood flow.

A method is described to quantify regional blood flow by thermal analysis. A weak temperature field is established in a tissue and for a thermal steady state, unidirectional heat flux and the associated temperature gradient are measured simultaneously across a small fixed segment of the tissue. This information is evaluated with probe calibrations for homogeneous isotropic fluids, with data from ancillary measurements in the nonperfused tissue and with values of specific heat and density of blood to express local blood flow in heat transfer [effective thermal conductivity (W. degrees C-1 . cm-1 x 10(-3) and/or in perfusion (ml . min-1 . cm-3)] terms. The technique measures local perfusion in small tissue volumes and is usable in acute or chronic experiments. Its accuracy is not a function of the absolute steady-state temperature of the tissue or of its metabolic heat production.

Animals↗