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Biomedical subjects

R Jensen

Publications and source records attributed to R Jensen.

At least 181 records · Page 10Linked to original sources
PubMed1985

The alpha and gamma subunits of 7S nerve growth factor are present in excess concentrations in the mouse submandibular gland.

The 7S nerve growth factor molecule, found in the mouse submandibular gland, is comprised of three distinct protein subunits named alpha, gamma and beta-NGF. In this paper, radioimmunoassays specific for each subunit were used to measure the concentrations of these subunits in homogenates of mouse submandibular gland. It was determined that there were excess concentrations of both the alpha and gamma subunits, more than enough to bind all of the beta-NGF in the gland to form 7S-NGF. The radioimmunoassay data was confirmed by gel filtration experiments. In the gel filtration experiments, the excess alpha and gamma subunits eluted at positions which would indicate that these excess subunits were free and not bound in the 7S-NGF complex. The identity of the excess alpha and gamma subunits was substantiated by ion exchange chromatography, isoelectric focusing polyacrylamide gels and immunoblotting experiments. In conclusion, there are considerable quantities of alpha and gamma subunits present in the submandibular gland which are not bound to beta-NGF. The functional significance of these excess concentrations of the alpha and gamma subunits is not known.

Animals↗
PubMed1985

Characterization of human brain S100 protein fraction: amino acid sequence of S100 beta.

Two major components of human brain S100 fraction were purified by HPLC and an amino acid sequence was elucidated for the S100 beta component. Human S100 proteins showed absorption spectra and amino acid compositions similar to S100 alpha and S100 beta from bovine brain. However, the relative amounts of the human proteins were 4% S100 alpha and 96% S100 beta by weight, while the bovine protein distribution was 47% S100 alpha and 53% S100 beta by weight. An amino acid sequence of human S100 beta was established by analysis of overlapping fragments generated by cyanogen bromide and trypsin cleavage. Three amino acid sequence differences between the human and bovine S100 beta were found at residues 7, 62, and 80. These differences were chemically conservative and compatible with minimum single base changes in the codon structures. These results document that S100 beta is a conserved protein among mammals and provide the necessary foundation for current clinical studies.

Amino Acid Sequence↗
PubMed1985

Deep venous thrombosis, pulmonary embolism and acute surgery in thrombophlebitis of the long saphenous vein.

Twenty-eight consecutive cases of acute superficial thrombophlebitis of the long saphenous vein above the knee were reviewed concerning presence of asymptomatic deep venous thrombosis and pulmonary embolism and early clinical results after surgical treatment. Contrast phlebography of the ipsilateral leg revealed asymptomatic involvement of major deep veins of the thigh or calf in 4 of 21 examined patients. Perfusion lung scanning and chest radiography demonstrated typical segmental perfusion defects consistent with pulmonary embolism in two of ten examined patients. High ligation and stripping of the phlebitic veins gave prompt cure in 19 patients, though in two who were simultaneously treated with anticoagulants there was troublesome bleeding. Simple high ligation was performed in nine patients without complications, but four of them had protracted phlebitic pain. The results indicated that preoperative phlebography and lung scanning are helpful in detecting associated asymptomatic disorders and for planning therapy in patients with clinically isolated, superficial thrombophlebitis of the long saphenous vein. The treatment of choice is acute high ligation with removal of all phlebitic veins. If anticoagulation is indicated because of concomitant deep venous thrombosis or pulmonary embolism, the initial procedure should preferably be limited to high ligation.

Adult↗
PubMed1985

Iliac vein obstruction associated with acute iliofemoral venous thrombosis. Results of early reconstruction using polytetrafluoroethylene grafts.

The results of iliac vein reconstruction performed early after secondary iliofemoral venous thrombosis were retrospectively evaluated. The review comprised seven patients who underwent acute thrombectomy combined with cross-femoral (4 cases) or iliocaval (3 cases) bypass procedures using polytetrafluoroethylene (PTFE) grafts. The clinical course, graft patency and venous physiology were studied. Five patients had a satisfactory clinical course, but one patient died of postoperative complications and another underwent leg amputation after 20 months. Contrast and radionuclide phlebograms showed that only two grafts were still patent after two years, but only one of these was still patent five years postoperatively. Clinical symptoms and physiologic parameters correlated poorly with graft patency, demonstrating the necessity of phlebography in evaluating patency rates after venous surgery. Our study indicates that early venous reconstruction using PTFE grafts does not result in satisfactory long-term patency rates. Further development of graft materials suitable for the venous system is required.

Acute Disease↗
PubMed1984

Faecal lipid chromatography. I. Quantitative determination with chromarods.

A new and original method is proposed for the qualitative and quantitative analysis of faecal lipids by thin-layer chromatography and detection through the flame ionization detector of an analyser (the Iatroscan TH 10). This method enables the rapid quantification of the different faecal lipid classes, including cholesterol, with great accuracy and reproducibility. In-series operations are possible with easy manipulation.

Chemical Phenomena↗
PubMed1984

Five SWI genes are required for expression of the HO gene in yeast.

High-frequency mating type interconversion in yeast requires the HO gene, which encodes a site-specific endonuclease that initiates the switching process. We have isolated and analyzed switching-defective mutants. These mutants define five complementation and linkage groups, SWI 1 to SWI 5. We have shown by two assays, Northern hybridization and beta-galactosidase activity in strains containing an HO-lacZ fusion, that mutants defective any SWI gene fail to express the HO gene. In addition, all of the swi mutants exhibit other phenotypes, the most notable being the inviability of double mutants defective in SWI 4 and in either SWI 1, SWI 2 or SWI 3. These results indicate that the SWI genes function in some way as positive regulators of HO expression and have additional cellular roles.

DNA, Fungal↗
PubMed1984

Fecal lipid chromatography--identification of an unusual fraction in relation to colon cancer.

The thin-layer chromatography of fecal lipids with revelation by phosphomolybdic reagent indicates the presence of an unusual fraction only in colon cancer patients. After isolation and identification, this fraction appears to be composed of coprostanol and its derivatives. The quantitative analysis of fecal neutral steroids in colon cancer patients compared to controls, patients with other digestive diseases and polypi shows a positive relationship between this fraction and colon cancer.

Adult↗
PubMed1984

Morphologic changes in rat urothelial cells during carcinogenesis: II. Image cytometry.

Improved early detection of neoplasia by screening of urothelial cells requires an understanding of the features distinguishing normal and neoplastic cell populations. We have begun a program of study based upon a rat model system for the controlled observation of early-stage lesions produced by the carcinogen N-butyl-N-(4-hydroxybutyl)- nitrosamine. Cells dissociated directly from normal and malignant urothelium were characterized by conventional cytopathology techniques and by quantitative microscopy (for nuclear texture and nuclear and cytoplasmic size, shape, and stain content) to derive a comprehensive picture of bladder tumor development. By following the changes that occur in the dissociated urothelial cells we have found that the nuclear area, total nuclear stain, nuclear shape, and the nuclear chromatin change significantly over a 48-wk interval as the lesions progress toward malignancy.

Animals↗
PubMed1984

Thrombectomy with temporary arteriovenous fistula: the treatment of choice in acute iliofemoral venous thrombosis.

The treatment of choice in acute iliofemoral venous thrombosis is still controversial. This prospective randomized study compares the results of conventional anticoagulation of 32 patients with the results obtained in 31 patients undergoing acute thrombectomy combined with a temporary arteriovenous fistula and anticoagulation. Early complications were few in both treatment groups, and significant pulmonary embolism developed in only one conservatively treated patient. At 6-month follow-up in all surviving patients, leg swelling, varicose veins, and venous claudication were more frequent after conservative treatment. Only 7% (2 of 27) of these patients were completely free from postthrombotic symptoms compared with 42% (10 of 24) of the operated patients (p less than 0.005). Contrast phlebography demonstrated an excellent venous outflow through the iliofemoral segment in 35% (9 of 26) of the conservatively treated and in 76% (16 of 21) of the operated patients (p less than 0.025). Open femoropopliteal veins with competent valves were recorded in 26% (7 of 27) in the conservative group and in 52% (12 of 23) in the thrombectomy group (p less than 0.05). Thus thrombectomy combined with arteriovenous fistula decreases early symptoms and preserves venous outflow and valvular function better than conservative treatment. This procedure is therefore recommended for young patients with acute iliofemoral thrombosis to avoid development of incapacitating postthrombotic sequelae.

Acute Disease↗
PubMed1983

Effect of fluphenazine on the stimulation of calcium-sensitive phospholipid-dependent protein kinase by 12-O-tetradecanoyl phorbol-13-acetate.

The addition of the tumor-promoting phorbol ester 12-O-tetradecanoyl phorbol-13-acetate resulted in activation of calcium-sensitive phospholipid-dependent protein kinase which was dependent on the presence of phospholipid but was essentially independent of calcium. Fluphenazine, which is an effective inhibitor of the ability of this phorbol ester to stimulate proliferation in calcium-deprived non-neoplastic cells, inhibited the enzyme in the absence or presence of the phorbol ester (Ki = 16 microM). Fluphenazine inhibition was competitive with phospholipid but non-competitive with 12-O-tetradecanoyl phorbol-13-acetate.

Animals↗
PubMed1983

Cause and pathogenesis of middle ear infection in young feedlot cattle.

Two populations of feedlot cattle--weaned calves and yearlings--suffered otitis media. In calves the disease was acute and epizootic and had a prevalence of about 400 cases per 2000 cattle, whereas in yearlings, it was chronic and sporadic and had a prevalence of 1 case per 2000 cattle. Clinical signs were facial paralysis, otorrhea, and head tilt. The middle ears from 64 dead calves and 22 dead yearlings were examined. Calf ears had acute infection, with exudate in air cells and rupture of tympanic membranes. Yearling ears had chronic infection, with exudate in air cells, rupture or destruction of tympanic membranes, and necrosis of air cell partitions. Mixtures of Pasteurella multocida and Corynebacterium pseudotuberculosis were isolated from diseased ears, but Pasteurella multocida predominated in acute infections and Corynebacterium pseudotuberculosis predominated in chronic infections.

Acute Disease↗
PubMed1983

Control of yeast cell type by the mating type locus: positive regulation of the alpha-specific STE3 gene by the MAT alpha 1 product.

The mating type locus (MAT) determines the three yeast cell types, a, alpha, and a/alpha. It has been proposed that alleles of this locus, MATa and MAT alpha, encode regulators that control expression of unlinked genes necessary for mating and sporulation. Specifically, the alpha 1 product of MAT alpha is proposed to be a positive regulator of alpha-specific genes. To test this view, we have assayed RNA production from the alpha-specific STE3 gene in the three cell types and in mutants defective in MAT alpha. The STE3 gene was cloned by screening a yeast genomic clone bank for plasmids that complement the mating defect of ste3 mutants. Using the cloned STE3 gene as a probe, we find that alpha cells produce STE3 RNA, whereas a and a/alpha cells do not. Furthermore, mat alpha 1 mutants do not produce STE3 RNA, whereas mat alpha 2 mutants do. These results show that the STE3 gene, required for mating only by alpha cells, is expressed only in alpha cells. They show also that production of RNA from the STE3 gene requires that alpha 1 product of MAT alpha. Thus alpha 1 positively regulates at least one alpha-specific gene by increasing the level of that gene's RNA product.

Cloning, Molecular↗
PubMed1983

Regulation of yeast mating-type interconversion: feedback control of HO gene expression by the mating-type locus.

The ultimate product of yeast mating-type interconversion is a stable a/alpha diploid cell. A haploid cell carrying the HO gene gives rise to a diploid cell in a two-step process: first, the cell switches mating type as a result of genetic rearrangement (cassette substitution) catalyzed by HO; then, cells of opposite type mate to form a/alpha diploids. Mating-type interconversion does not occur in a/alpha diploids despite the presence of the HO gene. We have identified a plasmid carrying the HO gene by screening a yeast clone bank (constructed in vector YEp13) for plasmids that allow mating-type switching by ho cells. The yeast segment responsible for mating-type interconversion integrates by homology at the ho locus, thus confirming that it carries HO. Using the HO gene as a probe, we find that strains with an active mating-type interconversion system produce HO RNA, whereas a/alpha HO/HO cells do not and that this inhibition requires products of both the MATa1 and MATa2 genes. Thus, mating-type interconversion does not occur in a/alpha HO/HO cells because the HO gene product is not synthesized. These results demonstrate the following: (i) The mating-type locus, proposed on genetic grounds to be a regulatory locus, controls expression of an unlinked gene (HO) at the level of RNA production. (ii) The HO gene is under negative feedback control: its expression is inhibited after successful completion of diploidization (formation of a/alpha diploids).

DNA, Fungal↗
PubMed1983

Physiologic and therapeutic aspects in congenital vein valve aplasia of the lower limb.

Ten patients with congenital vein valve aplasia verified at contrast phlebography were evaluated clinically and by physiologic examinations. All had orthostatic edema and varicose veins, but leg ulcers and other "postphlebitic" sequelae were infrequent. Foot volumetry and measurement of ambulatory foot vein pressures revealed a severe deep venous incompetence with a defective muscle pump function and considerable reflux. Eight limbs were operated on with conventional varicose vein surgery and physiologically re-examined six to 26 weeks after the operation. All had an improved ambulatory pressure reduction (p less than 0.001). Foot volumetry revealed better muscle pump function (p less than 0.01), while the reflux flow was unchanged. Surgery of the incompetent superficial venous system is therefore recommended in cases with deep venous insufficiency due to congenital vein valve aplasia.

Adolescent↗