Biomedical subjects

R L Mitchell

Publications and source records attributed to R L Mitchell.

9 recordsLinked to original sources

PubMed1990

Comparative anticalculus effect of dentifrices containing 1.30% soluble pyrophosphate with and without a copolymer.

A six-month, double blind, clinical study was conducted to determine the effect on supragingival calculus formation of a dentifrice containing 1.30% soluble pyrophosphate (from 2.0% tetrasodium pyrophosphate) and 1.50% of a copolymer of methoxyethylene and maleic acid, as compared to a dentifrice containing the same amount of soluble pyrophosphate but without the copolymer. This pyrophosphate/copolymer dentifrice contained the optimal ratio of pyrophosphate anion to copolymer required for obtaining a comparable anticalculus effect to a clinically proven anticalculus dentifrice containing 3.3% soluble pyrophosphate and 1.0% of a copolymer. The optimal pyrophosphate/copolymer ratio was determined by a series of in vitro laboratory and in vivo animal studies. Male and female adult subjects were stratified into three balanced groups according to baseline calculus scores. They received an oral prophylaxis and were assigned to the use of either the dentifrice containing soluble pyrophosphate and the copolymer, or to the dentifrice containing soluble pyrophosphate but without the copolymer, or to a placebo dentifrice that did not contain an anticalculus ingredient. The results of the three-month calculus examination indicated that the dentifrice containing soluble pyrophosphate and the copolymer provided a 33.66% reduction in supragingival calculus formation after an oral prophylaxis as compared to the placebo dentifrice. This reduction was statistically significant at the 99 percent level of confidence. The results of the six-month calculus examination indicated that the dentifrice containing the soluble pyrophosphate and the copolymer provided a 36.10% reduction in supragingival calculus formation after an oral prophylaxis, as compared to the placebo dentifrice. This reduction was also statistically significant at the 99% level of confidence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

The lateral limited thoracotomy incision: standard for pulmonary operations.

Four hundred sixty-eight consecutive thoracotomies for which the lateral limited thoracotomy incision was used are reviewed (1978 to 1988). The limited incision is a lateral muscle-splitting incision with preservation of the latissimus dorsi, splitting of the serratus anterior, and cutting of only the intercostal muscles without rib resection. Patients were designated unsuitable for operation if (1) biopsy-proved distant metastasis existed, (2) mediastinoscopy revealed extranodal metastasis, or (3) severe respiratory compromise resulted in shortness of breath at rest with a forced expiratory volume in 1 second of less than 0.75 L (four patients). Mean patient age was 60.9 (+/- 15.7) years. Surgical procedures included lobectomy (n = 317), pneumonectomy (n = 41), wedge resection (n = 82), resections of blebs or bullae (n = 17), thoracotomy and biopsy for unresectable lesion (n = 6), and decortication (n = 5). Pathologic analysis revealed 354 malignant tumors, 102 benign lesions, and 12 carcinoids. The perioperative mortality rate was 0.85% (4/468) and major morbidity was present in 2.9% (14/468). Mean operative time was 73.1 (+/- 32.2) minutes with a blood loss resulting in a mean decrease of the hematocrit value of 2.6 (+/- 2.5) gm; three patients were given a total of 7 units of blood. Most patients do not require a stay in the intensive care unit postoperatively (less than 10%). Hospital stay postoperatively was a mean of 6.1 (+/- 2.9 days. The limited incision is a significant factor in decreasing operative time, blood loss, postoperative pain and morbidity, and cost.

Aged↗

PubMed1979

Trace elements in soils and crops.

To demonstrate the total amounts to be expected in soils, the ranges of contents of some 60 trace elements in ten representative Scottish arable surface soils are compared with ranges in soil-forming rocks and with crustal averages. It is, however, the amounts potentially available to plants rather than the total contents that are biologically significant. In temperate climates, trace element mobilization is greatest when weathering takes place under conditions of impeded pedological drainage, leading to the formation of gleyed soils. Mobilized trace elements occur in arable surface soils largely in adsorbed and chelated forms, which are available to plants to a greater or smaller extent depending on the prevailing soil parameters and on the element in question. Different species take up different amounts of trace elements: the proportions in the various plant parts vary with the element and the stage of growth. Information is required about the mobilization and uptake of many elements about which little is at present known but which may affect the functions of essential elements through inter-element interactions. Systematic soil surveys in which soils are mapped by associations related to parent material, with their series related to genetic soil types, provide a useful countrywide guide to trace element status.

Agriculture↗

PubMed1979

Replication of vesicular stomatitis virus facilitated by Shope fibroma virus in vivo.

Previous studies show that Shope fibroma virus facilitates replication of vesicular stomatitis virus (VSV) in some rabbit cells grown in vitro. In the present investigation, the possibility that these two viruses can also interact in vivo was determined. Rabbits inoculated intradermally with both viruses together, or each separately, were examined for the formation of lesions or tumors and for the production of infectious virus. The presence of VSV interfered with tumorigenesis by Shope fibroma virus. In tumors already formed, production of infectious VSV was greater than in normal skin. Hence, each virus affected the other. Sera and tissues of normal rabbits were found to contain a substance which inhibits VSV; this may act to limit replication of VSV in rabbit skin. In addition, cultured rabbit skin cells appeared to adsorb VSV inefficiently. When persistently infected by Shope fibroma virus, however, adsorption of VSV was markedly improved. Our results suggest that in vivo Shope fibroma virus may facilitate adsorption of VSV to reduce the effect of a natural inhibitor and consequently enhance production of infectious virus.

Adsorption↗

PubMed1977

Coronary artery spasm. medical management, surgical denervation, and autotransplantation.

Coronary artery spasm was induced by intravascular administration of ergonovine maleate (Ergotrate) during cardiac catheterization. In 78 patients suspected to have Prinzmetal's angina, no morbidity or death has resulted despite complete occlusive spasm in two and three coronary arteries. Typical EKG changes and akinesia of the myocardium in the distribution of the occluded vessels documented functional myocardial ischemia during spasm. The occlusive spasm is readily reversed by sublingual or intravascular nitroglycerin, and ventricular contractility returns to normal following relief of spasm. Occlusive spasm has been demonstrated in 15 patients with clinical evidence of Prinzmetal's angina. Symptoms have been effectively relieved by coronary vasodilators in 10 patients. Of the 5 patients in whom medical therapy failed, 4 were treated surgically. These 4 patients were in the intensive care unit with protracted, prolonged pain, subendocardial infarctions, and persistent failure of coronary vasodilators. Aorta-coronary bypass grafts have been combined with total cardiac denervation by autotransplantation (one patient) and total cardiac denervation by stripping of the great vessels (3 patients). Two of the patients treated by cardiac denervation died in the early postoperative period. The patient treated by autotransplantation has total relief of symptoms but persistent spasm on angiography. The angiographic demonstration of occlusive coronary spasm remains a valuable diagnostic tool to document definitively the presence of spasm. The surgical results question the value of surgical intervention in this disease.

Adult↗

PubMed1976

A note on the lack of difference in fertility between old and young hens when inseminated with frozen semen.

Semen was frozen (in glycerol) from 24 males (9 months of age) of a commercial broiler line and was inseminated intravaginally into old (19 months of age) and young (7 months of age) commercial Leghorn females. Duration of fertility, percent fertility during duration and percent hens fertile were measured. The means for old and young hens respectively, were: duration of fertility (1.4 +/- 0.4 and 1.6 +/- 0.5 days), percent fertility (19.1 +/- 5.1 and 15.9 +/- 5.1) and percent hens fertile (29.2 +/- 7.7 and 25.3 +/- 7.2). The "t" test revealed no significant (P greater than 0.05) differences between old and young females in fertility.

Age Factors↗

PubMed1976

Fertility of frozen chicken semen after intravaginal and intrauterine inseminations using various concentrations and equilibration times of dimethylsulfoxide and a range of freezing and thawing rates.

The use of dimethyl sulfoxide (DMSO) as a cryoprotective agent for freezing chicken semen was examined with respect to intravaginal (I.V.) and intrauterine(I.U.) inseminations. Semen diluted in DMSO was subjected to various freeze rates, equilibration times and thawing rates. Various concentrations of DMSO were examined as was the effect of diluting DMSO with phosphate buffer and Lake's solution. There was no significant (p greater than 0.05) effect of rate of freeze (ranging from 1.3 degrees C to 7.2 degrees C. per min) on fertility. However, rapid thawing in an ice bath resulted in a longer (p less than 0.05) duration of fertility than thawing at 1 degree C. per min., but had no effect on percent fertility during duration or percent hens fertile. Equilibration time and concentration of DMSO had no significant (p greater than 0.05) effects on fertility. There was no interaction between insemination route and Lake's solution vs. phosphate buffer with respect to duration of fertility. It was concluded that intrauterine (I.U.) insemination resulted in superior fertility to intravaginal (I.V.) inseminations with semen frozen in DMSO.

Animals↗

PubMed1975

Cricopharyngeal myotomy: treatment of dysphagia.

Six patients are presented who underwent cricopharyngeus myotomy for dysphagia. The clinical history and cine studies appear to be the most useful assessments in defining patients with dysphagia who may improve after a myotomy. Etiological factors which may precipitate poor coordination of the swallowing mechanism and a relative cricopharyngeus muscle obstruction include neuromuscular disorders, radical oral surgery, central nervous disease, and idiopathic disorders, although the exact physiology of the cricopharyngeus muscle in health and disease is not as yet delineated, the muscle is being implicated in many problems as the inciting factor of upper esophageal dysphagia. The operation of cricopharyngeus myotomy is a relatively simple procedure and should be done with little morbidity and mortality in properly selected cases.

Adult↗

PubMedDate not supplied

Structural alteration of viral homologue of receptor proto-oncogene fms at carboxyl terminus.

A role for proto-oncogenes in the regulation and modulation of cell proliferation has been suggested by the findings that the B-chain of platelet-derived growth factor (PDGF) is encoded by the proto-oncogene sis and that the erb-B oncogene product is a truncated form of the epidermal growth factor (EGF) receptor. Furthermore, the product of the proto-oncogene fms (c-fms) may be related or identical to the receptor for macrophage colony-stimulating factor (CSF-1). v-fms is the transforming gene of the McDonough strain of feline sarcoma virus (SM-FeSV) and belongs to the family of src-related oncogenes which have tyrosine-specific kinase activity. Furthermore, nucleotide sequence analysis of the v-fms gene product revealed topological properties of a cell-surface receptor protein. To elucidate the features involved in the conversion of a normal cell-surface receptor gene into an oncogenic one, we have now determined the complete nucleotide sequence of a human c-fms complementary DNA. The 972-amino-acid c-fms protein has an extracellular domain, a membrane-spanning region, and a cytoplasmic tyrosine protein kinase domain. Comparison of the feline v-fms and human c-fms sequences reveals that the proteins share extensive homology but have different carboxyl termini.

Amino Acid Sequence↗