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P R Gordon

Publications and source records attributed to P R Gordon.

At least 37 records · Page 2Linked to original sources
PubMed1988

Demonstration of a choline requirement for optimal keratinocyte growth in a defined culture medium.

Nutrient requirements for proliferation and differentiated function of individual cell types can be determined using cell culture methodologies. Human epidermal keratinocytes are stimulated to grow by choline supplementation in the presence of myo-inositol when grown in a commercial nutrient medium containing six other defined supplements. The optimal range of choline concentrations varied among donor cell lines, but consistently fell between 36 microM and 180 microM. Addition of 72 microM choline increased cell yield to 250 +/- 38% of that produced by myo-inositol supplementation alone and 92 +/- 8% of that produced by addition of a highly mitogenic hypothalamic extract, which was previously required for good growth in this culture system. Supplementation of the basal medium with both the extract and choline resulted in 165 +/- 13% of the cell yield observed with the extract addition alone. Supplementation with other phospholipid precursors did not further increase keratinocyte growth. Neither dermal fibroblasts nor epidermal melanocytes were stimulated by supplementation with choline, suggesting the high keratinocyte requirement is unusual. This completely defined culture medium for keratinocyte growth should prove useful in analyzing the role of phospholipids and other nutrients in human epidermis.

Cell Count↗
PubMed1988

Vitamin D, its precursors, and metabolites do not affect melanization of cultured human melanocytes.

Exposure of the skin to sunlight results in both tanning and vitamin D3 production. It has therefore been suggested that vitamin D3 or its active metabolite 1,25-dihydroxyvitamin D3 may be the mediator of UV-induced melanogenesis. To test this hypothesis, newborn foreskin-derived melanocytes were cultured in paired dishes in hormone-supplemented medium with 2% serum containing no detectable vitamin D3 or in the same medium containing 10(-8) or 10(-10) M of either provitamin D3, lumisterol, previtamin D3, vitamin D3, 25-hydroxyvitamin D3, or 1,25-dihydroxyvitamin D3. After 10 days, cell number in cultures containing vitamin D compounds was 93%-140% of unsupplemented controls and melanin content was 60%-120% of control, with no significant difference in either parameter for any compound tested. In separate experiments, human melanocytes and Cloudman S91 melanoma cells were repeatedly irradiated with physiologic doses of simulated sunlight and incubated between irradiations with provitamin D3, previtamin D3, vitamin D3, or 1,25-dihydroxyvitamin D3. Irradiated cultures had a 90%-95% inhibition of cell growth associated with a 200%-800% increase in melanin content per cell relative to controls, but there was no effect of any vitamin D compound on either cell type. Neither cultured human melanocytes nor S91 cells showed evidence of the cytosolic 1,25-dihydroxy-vitamin D3 receptor binding by sucrose density gradient analysis using radiolabeled 1,25-dihydroxyvitamin D3. The combined data strongly suggest that neither vitamin D3 nor its precursors or metabolites directly mediate melanogenesis in these cells.

Cells, Cultured↗
PubMed1988

Human epidermal keratinocytes in culture convert thyroxine to 3,5,3'-triiodothyronine by type II iodothyronine deiodination: a novel endocrine function of the skin.

Cultured human keratinocytes converted T4 to T3 by type II iodothyronine deiodination. Homogenates of keratinocytes cultured from neonatal foreskin or adult arm skin had similar mean T4 5'-deiodinating activities. Conversion of T4 to T3 by intact cells was demonstrable in cultures from neonatal and adult donors. Only phenolic ring deiodination occurred in the cultured cells and their homogenates, the apparent Michaelis constant for T4 was 12 nmol/L, and T4 and rT3 each inhibited 5'-deiodination of the other. T4 5'-deiodination was unaffected by addition to the assay mixture of 1 mumol/L T3, but was inhibited less than 10% by 1 mmol/L 6-n-propyl-2-thiouracil, 50% by 270 nmol/L iopanoic acid, 50% by 9.4 mumol/L 3,5-diiodo- 3',5'-dimethyl-L-thyronine, and 33% by 42 mumol/L amiodarone. When keratinocytes were cultured for 3-4 days in medium containing iodothyronine-free fetal calf serum, the T4 5'-deiodination rates in homogenates doubled; this increase was prevented by restoring a physiological free T4 concentration, but not by a supraphysiological T3 concentration. Homogenates of fresh whole skin or fetal cadaveric epidermis did not convert T4 to T3 in measureable amounts, although one epidermal homogenate had low level T3 typrosyl-ring deiodinating activity. These results suggest that human epidermal type II iodothyronine deiodination in man might conceivably contribute to the intracellular T3 content of the skin and even to serum T3 concentrations, especially in hypothyroidism.

Cells, Cultured↗
PubMed1987

Pericatheterization risk factors in left main coronary artery stenosis.

Patients with left main (LM) coronary artery disease (CAD) have an unexplained high incidence of complications during diagnostic cardiac catheterization. This study identifies pericatheterization risk factors for major complications in patients with LM CAD (stenosis at least 50%). Complications were defined as ventricular fibrillation not related temporally to coronary injection, persistent angina, acute myocardial infarction, profound hypotension and death during or within 24 hours of catheterization. One hundred seven consecutive cases of LM CAD (11 with complications and 96 without) were reviewed with respect to variables potentially related to complications. Patients who had angina in the 24 hours before catheterization were at increased risk. Four of 13 patients with angina (31%) and 7 of 94 (7%) without angina had complications (p less than 0.05). Distance from the catheter tip to the lesion also was related to complications (9 of 38 [24%] with tip 6.0 mm or less from lesion and 2 of 65 [3%] with tip more than 6.0 mm from lesion, p less than 0.05). No relaxation was found between complications and New York Heart Association functional class, technique (femoral vs brachial), performance of ventriculography, number of coronary injections, amount of contrast injected, severity of LM stenosis, number of major arteries with 75% or more diameter stenosis, mean arterial pressure, left ventricular end-diastolic pressure and left ventricular ejection fraction.

Angina Pectoris↗
PubMed1987

Effects of iron-, manganese-, or magnesium-deficiency on the growth and morphology of Euglena gracilis.

Iron-, manganese-, or magnesium-deficiency has been induced in Euglena gracilis. Each arrests cell proliferation, decreases the intracellular content of the deficient metal, and increases that of several other metals. Light and electron microscopy of stationary phase cells reveal that Fe-deficient (-Fe) cells are similar in size and shape to control organisms. Magnesium-deficient (-Mg) cells, however, are larger, and approximately 14% are multilobed, containing 2 to 12 lobes of equal size emanating from a central region. Individual (-Mg) cells and each lobe of multilobed cells contain a single nucleus. Manganese-deficient (-Mn) organisms are morphologically more heterogeneous than (-Fe) or (-Mg) cells. Most are spherical and larger than controls. Approximately 15% are multilobed but, unlike (-Mg) cells, contain lobes of unequal size with either zero, one, or several nuclei present in each. Nuclei of (-Mn) cells differ in size and shape from those of control, (-Fe), or (-Mg) cells. All three deficient cell types accumulate large quantities of paramylon. Other cytoplasmic structures, however, appear normal. Addition of Fe, Mn, or Mg to the respective deficient stationary phase cultures reverses growth arrest and restores normal morphology. The results suggest that Fe-, Mn-, and Mg-deficiencies affect different stages of the E. gracilis cell cycle.

Cell Nucleus↗
PubMed1986

Euglena gracilis chromatin: comparison of effects of zinc, iron, magnesium, or manganese deficiency and cold shock.

The effects induced by Fe, Mn, or Mg deficiency or cold shock on the DNA content and histones of Euglena gracilis have been examined and compared to those produced by Zn deficiency. The DNA content of the stationary-phase organisms used as controls is 2.1 micrograms/10(6) cells. The DNA of stationary-phase iron-deficient (-Fe), magnesium-deficient (-Mg), manganese-deficient (-Mn), zinc-deficient (-Zn), and cold-shocked (CS) cells is increased to 3.0, 4.6, 6.2, 3.8, and 3.8 micrograms/10(6) cells, respectively. The electrophoretic mobilities of proteins solubilized with 0.4 N H2SO4 from CS, -Fe, -Mg, and -Mn cells are nearly identical and are characteristic of the five histone classes, H1, H2A, H2B, H3, and H4. In contrast, no histones are found in the equivalent acid extract from -Zn cells. The effect of micrococcal nuclease on chromatin from control, CS, and -Zn cells was examined. The chromatin of CS cells is 1.2-fold while that from -Zn cells is 10-30-fold more resistant to micrococcal nuclease digestion than is the chromatin of control cells. Thus, the chromatin of cells grown in Zn-deficient conditions differs markedly from that of organisms cultured in media deficient in Fe, Mn, or Mg or exposed to cold shock.

Acclimatization↗
PubMed1986

Relative responsiveness of cultured human epidermal melanocytes and melanoma cells to selected mitogens.

Early cellular events in the malignant transformation of melanocytes to melanoma are virtually unknown. In vitro investigation of this phenomenon has been hampered by the fastidious nature of the human epidermal melanocyte, which has proven difficult to cultivate. The present study compares responsiveness of cultured human epidermal melanocytes and established melanoma cell lines to serum, cholera toxin, and melanocyte growth factor (MGF), three established melanocyte mitogens. Four of four established human melanoma lines were substantially stimulated by fetal bovine serum, as were newborn foreskin-derived epidermal melanocytes. In contrast, none of the four melanoma lines responded to hypothalamic preparations containing MGF that consistently produced an approximately 30-fold increase in newborn melanocyte cell yield over a 2-week period. Cholera toxin, required for successful establishment of primary melanocyte cultures, had small and variable effects on the melanoma lines, with slight stimulation in one case, moderate inhibition in another, and essentially no effect in two others. These data suggest that transformation of epidermal melanocytes to melanoma often involves at least one phenotypic change resulting in escape from MGF regulation and another associated with insensitivity to cyclic AMP modulation; while at least some of the pathways conferring serum dependence are unaltered. Improved culture systems for the human epidermal melanocyte should facilitate further studies into the mechanism of its malignant conversion and may provide useful insights for the prevention and treatment of human melanoma.

Cell Division↗
PubMed1986

Load regulation of the properties of adult feline cardiocytes. The role of substrate adhesion.

We have recently described rapid and reversible changes in cardiac structure, function, and composition in response to surgical load alteration in vivo. In the present study, we used a simple, well-defined in vitro experimental model system, consisting of terminally differentiated quiescent adult cat ventricular cardiocytes maintained in serum-free culture medium, to assess more definitively the role of loading conditions in regulating these same biological properties of heart muscle. Cardiocytes considered to be externally loaded were adherent throughout their length to a protein substrate, such that the tendency for the ends of the cells to retract was prevented. Cardiocytes considered to be unloaded were not adherent to a substrate and, thus, were free to assume a spherical shape. Cardiocyte structure and surface area were assessed, in initially identified cells, both by serial light microscopy and by terminal electron microscopy. Cardiocyte function was assessed in terms of the ability to exclude trypan blue, to remain quiescent with relaxed sarcomeres containing I-bands, and to shorten in response to electrical stimulation. Cardiocyte composition was first assessed by quantitative gel electrophoresis of proteins and then by microfluorimetric measurement of ribonucleic acid, protein, and deoxyribonucleic acid. In addition, cardiocyte incorporation of [3H]thymidine into deoxyribonucleic acid and [3H]uridine into ribonucleic acid were measured. Loading via substrate adhesion was found to be very effective in terms of each of these measurements in retaining the differentiated features of adult cardiocytes for up to 2 weeks in culture; unattached and thus unloaded cardiocytes quickly dedifferentiated. Conditions thought to stimulate cardiac growth, including catecholamine stimulation, were found to be ineffective. These experiments demonstrate that external load has a primary role in the maintenance of the basic differentiated properties of adult mammalian cardiocytes.

Animals↗
PubMed1983

Zinc deficiency and impaired platelet aggregation in guinea pigs.

Previous studies have shown that acute zinc deficiency results in impaired platelet aggregation in humans and rats as well as decreased sensitivity to such aggregating agents as ADP, arachidonate and collagen. This study was designed to evaluate the effect of zinc deficiency on platelet function and other pathology in the guinea pig. Guinea pigs of mixed sex were fed a purified diet based on soybean protein (1 ppm Zn) or a similar control diet (100 ppm Zn). In one trial weanling guinea pigs, weighing about 150 g, were fed the diets for 22 days. Those fed the basal diet failed to grow after 2 weeks, and food consumption decreased at this time although it did not become cyclic. They developed skin lesions; zinc concentrations were decreased in plasma, red cells and liver. There was no effect on the packed cell volume. Guinea pigs weighing 350 g and fed the basal diet for 18 days showed little or no effect on growth rate and food intake, but tissue zinc levels were decreased. Plasma zinc dropped significantly within 24 hours. Platelet aggregation in response to minimal levels of ADP and a prostaglandin endoperoxide analog (U-44069) was severely impaired. Aggregation in response to bovine thrombin (1 unit/ml) was significantly delayed, but the partial response in the presence of indomethacin was not affected by zinc deficiency. The results suggest that impaired platelet aggregation is a general sign of zinc deficiency in mammals and that the function of the physiological eicosanoids is impaired.

Adenosine Diphosphate↗
PubMed1983

Platelet arachidonate metabolism and platelet function in zinc-deficient rats.

To determine the effect of zinc status on arachidonate metabolism and the initiation of aggregation by a prostaglandin endoperoxide analog (U-44069), immature rats were fed for 5 days a low zinc (less than 1 ppm) or control (100 ppm Zn) diet based on soybean protein. In vitro production of thromboxane B2 (TXB2) by platelet-rich plasma after stimulation by either arachidonate (0.2 mM) or ADP (0.2 microM) was not changed by dietary zinc deprivation, even though bleeding time was prolonged. Oxygenation of exogenous arachidonate, catalyzed by either the cyclooxygenase or lipoxygenase pathway, was not affected by zinc deficiency. Platelet aggregation in response to the prostaglandin endoperoxide analog at both 8 and 16 microM was impaired by dietary zinc deprivation. While short-term zinc deprivation decreased platelet response to minimal levels of aggregating agents, production of arachidonate metabolites was unimpaired. It is postulated that platelet response to the products of arachidonate metabolism is reduced.

Adenosine Diphosphate↗
PubMed1982

Effect of acute zinc deprivation on plasma zinc and platelet aggregation in adult males.

In view of earlier results obtained with rodents, the present study was designed to investigate the effect of acute zinc deprivation in man on plasma zinc concentration and the response of platelets to aggregating agents. Three adult men consumed a formula diet based largely on soybean protein for 12 to 14 days. During the control period the diet was supplemented with 12 mg zinc per day. Without supplementation the diet supplied approximately 0.5 mg zinc per 3.0 Mcal; it contained 0.7 ppm zinc, and 0.2% phytate. After removal of the zinc supplement plasma zinc dropped rapidly and reached a minimum by the 5th day. There was a wide diurnal variation in plasma zinc concentration in one subject with the overnight fasting value being the highest and decreasing soon after the morning meal. Platelet aggregation in response to ADP and arachidonate was impaired when plasma zinc was 60 micrograms/dl or less and was restored to normal within 19 h of oral zinc supplementation. These results demonstrate that plasma zinc can be rapidly decreased by dietary zinc deprivation and that extracellular zinc plays an important role in platelet aggregation.

Adenosine Diphosphate↗
PubMed1981

Astatine-211--tellurium radiocolloid cures experimental malignant ascites.

An investigation of the efficacy of astatine-211--tellurium colloid for the treatment of experimental malignant ascites in mice reveals that this alpha-emitting radiocolloid can be curative without causing undue toxicity to normal tissue. By comparison, negatron-emitting phosphorus-32 as colloidal chromic phosphate had no antineoplastic activity. The most compelling explanation for this striking difference is the dense ionization and short range of action associated with alpha-emission. These results have important implications for the development and use of alpha-emitters as radiocolloid therapy for the treatment of human tumors.

Alpha Particles↗
PubMed1980

Rat platelet aggregation impaired by short-term zinc deficiency.

Platelets in plasma from immature male rats fed a complete purified diet exhibited biphasic aggregation in response to 0.2 microM adenosine diphosphate (ADP). Rats fed the diet without added zinc (< 1 ppm) for 1 week failed to show the secondary phase of aggregation. Aggregation in response to collagen and arachidonic acid was almost totally absent in the zinc-deficient plasma, but the response to the divalent cation ionophore, A23187, was normal. The results demonstrate that zinc is essential for platelet function and suggest that it is involved in the platelet metabolism of arachidonic acid.

Adenosine Diphosphate↗
PubMed1980

Frozen section examination of endometrial curettings. An aid to the rapid diagnosis of ectopic pregnancy.

The maternal mortality resulting from extrauterine pregnancy has been related to delayed intervention following the onset of symptoms. Therefore, methods that can rapidly include or exclude an ectopic pregnancy are of value. In selected cases dilatation and curettage, with frozen section examination of the curetted tissue, has been utilized to confirm an abnormal intrauterine pregnancy and vitually rule out an extrauterine pregnancy.

Adult↗