Biomedical subjects
F M Davis
Publications and source records attributed to F M Davis.
Localization of highly repeated HindIII fragments of Novikoff rat DNA to the nucleolus.
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Bacterial contamination of radial artery catheters.
A prospective survey of 113 radial artery catheters showed a total contamination rate using an enrichment media culturing technique of 39%. The yield from routine culturing alone was only 9%. In six cases pathogenic bacteria were isolated. In this study no correlation between contamination and aspects of catheter insertion and management was shown.
Nucleolar antigen found in several human tumors but not in the nontumor tissues studied.
Rabbit antibodies to nucleoli isolated from HeLa cells produced bright nucleolar fluorescence in HeLa cells by the indirect immunofluorescence technique. After absorption with fetal bovine serum and placental nuclei, the IgG still produced bright nucleolar fluorescence in 12 human tumor cells including HeLa, HEp-2, cultures of prostate and mammary carcinomas, the Goldenberg GW-39 colon tumor, and biopsy specimens of prostatic, adrenal cortical, thyroid, and squamous cell carcinomas, a hairy cell leukemia of the spleen, a hepatic metastasis of an adenocarcinoma of the colon, and an osteogenic sarcoma. Bright nucleolar fluorescence was not produced in nine nontumor human cells including biopsy specimens of bone marrow, kidney, placenta, thyroid, liver, and prostate, peripheral blood buffy coat, and cultures of normal skin fibroblasts. Nucleolar fluorescence with the absorbed IgG was prevented in HeLa cells by pretreatment of the cells with acid, base, and proteases but not by pretreatment with nucleases; absorption of this IgG with extracts of HeLa nucleoli prevented the nucleolor fluorescence in HeLa and other human tumor cells.
A nucleolar antigen found in a broad range of human malignant tumor specimens.
With rabbit antibodies to nuclear 0.01 M Tris-HCl, pH 8, extract or "nucleolar preparations" of human HeLa S3 cells and fluorescein-labeled goat anti-rabbit antibodies, bright nucleolar immunofluorescence was observed in 61 or 63 human adenocarcinomas, squamous cell carcinomas, sarcomas, hematological neoplasms, and other malignant tumors. With these antibodies, nucleolar immunofluorescence was not found in 23 normal tissue specimens, 10 benign adenomas and hyperplastic tissues, and 8 specimens of inflammatory diseases. In the nontumorous tissues examined, positive nucelolar fluorescence was found in a few sections of a gastric ulcer and chronic ulcerative colitis which have been known propensities for malignant change; these areas may have been undergoing focal malignant changes.
Purification and partial characterization of nucleolar antigen-1 of the Novikoff hepatoma.
A nucleolar chromatin antigen (NoAg-1) found in Novikoff hepatoma but not in normal liver has been purified to homogeneity as shown by two-dimensional gel electrophoresis. Initial purification of NoAg-1 was partially achieved by isolation of nucleolar chromatin and fractionation of its proteins by successive extraction with solutions of increasing salt concentration. Further purification of this antigen was achieved by affinity and hydroxylapatite chromatography. Although approximately 50% of the NoAg-1 antigen was in the 0.6 M NaCl extract of Novikoff nucleoli, it was less pure than in the 2 M NaCl:5 M urea extract which contained 25% of the NoAg-1 at a purity of 40%. The highly purified NoAg-1 had an approximate molecular weight of 60,000 and pl of 5.1; the yield of NoAg-1 was 0.22% of the total nucleolar proteins.
Radial artery cannulation: influence of catheter size and material on arterial occlusion.
A randomized, prospective trial of four different cannulae used for percutaneous radial artery cannulation was carried out in one hundred and forty-eight patients undergoing cardiopulmonary bypass surgery. Arterial occlusion was assessed using a modified Allen's test and an ultrasonic flow monitor. The incidence of complete occlusion eight days after decannulation was 34% for 18-gauge polypropylene and 0% for 20-gauge Teflon cannulae. Both the size and material of the cannula are important factors in the occurrence of arterial occlusion. This complication can largely be eliminated by the use of small Teflon cannulae.
Arachnoid cysts of the middle cranial fossa: surgical considerations.
Three cases of arachnoid cysts of the middle cranial fossa are presented. CT imaging before and after peritoneal shunting of these cysts demonstrates the therapeutic value of this cerebrospinal fluid diversionary procedure. Many important facets of this disease such as cyst genesis, histology, natural history and other forms of therapy as reported by various authors in the recent literature are discussed.
Differences in nucleolar antigens of rat liver and Novikoff hepatoma ascites cells.
Antisera to nucleoli of Novikoff hepatoma ascites and normal rat liver cells were produced in rabbits by injection of whole, isolated nucleoli. These antisera have been used to compare the nucleolar antigens that were partially fractionated by differential solubilization from nucleoli. Fourteen antigens were detected by these antisera; ten of these antigens were detected by both antisera. Ouchterlony double diffusion analysis of soluble extracts from normal rat liver and Novikoff hepatoma ascites nucleoli and fetal rat liver nuclei provided evidence for antigens found only in liver extracts, only in tumor extracts, or only in tumor and fetal extracts. Antisera preabsorbed to remove antibodies to common antigens of liver and tumor provided confirmatory evidence for one nucleolar antigen in liver that was not found in tumor or fetal rat liver, one antigen in tumor that was not found in adult or fetal rat liver, and three antigens in both tumor and fetal rat liver that were not found in adult rat liver. In addition, the antitumor nucleolar antiserum preabsorbed with liver nuclear extracts still produced positive nucleolar fluorescence in Novikoff hepatoma ascites cells but not in liver cells. Conversely, anti-liver nucleolar antiserum preabsorbed with tumor nucleolar extracts did not produce detectable tumor nucleolar fluorescence but did produce positive fluorescence in liver nucleoli.
Nuclear matrix of HeLa S3 cells. Polypeptide composition during adenovirus infection and in phases of the cell cycle.
A subnuclear fraction has been isolated from HeLa S3 nuclei after treatment with high salt buffer, deoxyribonuclease, and dithiothreitol. This fraction retains the approximate size and shape of nuclei and resembles the nuclear matrix recently isolated from rat liver nuclei. Ultrastructural and biochemical analyses indicate that this structure consists of nonmembranous elements as well as some membranous elements. Its chemical composition is 87% protein, 12% phospholipid, 1% DNA, and 0.1% RNA by weight. The protein constituents are resolved in SDS-polyacrylamide slab gels into 30-35 distinguishable bands in the apparent molecular weight range of 14,000 - 200,000 with major peptides at 14,000 - 18,000 and 45,000 - 75,000. Analysis of newly synthesized polypeptides by cylindrical gel electrophoresis reveals another cluster in the 90,000-130,000 molecular weight range. Infection with adenovirus results in an altered polypeptide profile. Additional polypeptides with apparent molecular weights of 21,000, 23,000, and 92,000 become major components by 22 h after infection. Concomitantly, some peptides in the 45,000-75,000 mol wt range become less prominent. In synchronized cells the relative staining capacity of the six bands in the 45,000-75,000 mol wt range changes during the cell cycle. Synthesis of at least some matrix polypeptides occures in all phases of the cell cycle, although there is decreased synthesis in late S/G2. In the absence of protein synthesis after cell division, at least some polypeptides in the 45,000-75,000 mol wt range survive nuclear dispersal and subsequent reformation during mitosis. The possible significance of this subnuclear structure with regard to structure-function relationships within the nucleus during virus replication and during the life cycle of the cell is discussed.
Thermal balance during cardiopulmonary bypass with moderate hypothermia in man.
In six patients undergoing coronary vein graft operations under cardiopulmonary bypass and hypothermia, the temperatures of arterial and mixed-venous blood, nosopharynx, oesophagus, liver, rectum, deltoid and vastus lateralis muscles and 10 skin sites were recorded. Whole-body oxygen consumption was measured before cooling and twice during hypothermia. On average, a patient lost 1000 kJ of heat by the end of hypothermia, of which 84% was lost to the heat-exchanger and pump circuit. Evaporative and convective loss amounted to 380 kJ, while the patient's metabolism supplied 220 kJ. During rewarming, the pump returned 670 kJ to the patient. Nasopharyngeal temperature reflected accurately venous, oesophageal and hepatic temperatures in the steady state; however, it was slow to reflect changes. Compared with other sites, muscle remains warmer during hypothermia and cooler after rewarming.
Cervical disc disease and other causes of upper extremity pain.
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Effect of sterol replacement in vivo on the fatty acid composition of Tetrahymena.
The addition of ergosterol to cultures of Tetrahymena pyriformis results in (a) the accumulation of the sterol by the cells; (b) the inhibition of the synthesis of the pentacyclic triterpenoid alcohol, tetrahymanol; (c) the replacement of tetrahymanol by ergosterol in the ciliate membranes. The dry weight and lipid content of sterol-supplemented ciliates did not differ from the controls. Examination of the lipid classes revealed no change in composition except for a higher content of ergosterol in supplemented cells than tetrahymanol in control cultures. The relative proportions of triglycerides, the major classes of polar lipids, 1-alkyl phospholipids and phosphonolipids, appeared unaltered. A complex array of fatty acids is found in this ciliate. Several acids not reported previously in this organism were isolated and identified, and the novel fatty acid 18:2 delta 6, 11, was found in substantial amounts. Ergosterol supplementation altered the proportions of the fatty acids, although not all lipid classes were affected to the same extent. The changes noted were of three general types: (a) a shortening of the fatty acyl chain length in the acids of the normal series; (b) a lowering in the degree of unsaturation; (c) a discrimination between two isomers of lionoleate, 18:2 delta 6, 11 and 18:2 delta 9, 12. The former is elevated in the presence of ergosterol while the latter is depressed. Each class of polar lipids has a distinctive fatty acid composition. Among the glycerophospholipids, cardiolipin and phosphatidylcholine were least affected, while the mixture of 1-alkyl-2-acyl-sn-glycero-3-(2-aminoethyl)-phosphonate and 1,2-diacyl-sn-glycero-3-(2-aminoethyl)-phosphonate was most markedly altered. Sphingolipid fatty acid composition was influenced by ergosterol supplementation. Two changes were noted: (a) a reduction in the length of the hydrocarbon chain; (b) an increase in the proportion of alpha-hydroxy acids. The impact of ergosterol on the fatty acid composition of the polar lipids may be on fatty acid biosynthesis, on incorporation of fatty acids, or on the turnover rates of the fatty acyl groups. Ergosterol is concentrated in the ciliary (limiting) membrane, as are the polar lipids most affected. This localization allows the speculation that the change in fatty acid composition may be related to the maintenance of optimal membrane properties upon the introduction of the sterol.
Measurement of PO2 and PCO2 of gases and liquids at 2Ata using externally pressurized electrodes.
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Establishing a private practice in neurological surgery; preparations, problems and pitfalls.
In summary, the young neurosurgeon entering private practice will find he will have to make many non-medical decisions for which he has had little or no preparation during the course of his lengthy training. Just as one spends time planning a careful curriculum in leading to the specialty of neurological surgery, he must also dedicate many hours to establishing a private practice in that specialty. The time spent in investigating these problems in advance will minimize the frustrations in attaining the goal which we are all striving to achieve-personal satisfaction in the delivery of excellent health care.