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Biomedical subjects

D H Russell

Publications and source records attributed to D H Russell.

At least 199 records · Page 11Linked to original sources
PubMed1977

Cytoplasmic and nuclear protein kinases during the cell cycle.

Nuclear and cytoplasmic protein kinases were measured during the traverse of synchronous CHO cultures through G1 into S phase. Cells were synchronized by selective detachment of cells blocked in metaphase using colcemid. Nuclei were isolated and the protein kinases extracted from the nuclear preparation with 0.6 M NaCl. This procedure solubilized greater than 90% of the total protein kinase activity present in the nuclear preparation. DEAE chromatography of this extract showed 5 apparently different ionic forms of nuclear protein kinases. The nuclear protein kinases preferred casein and phosvitin to histone as substrates and were cyclic AMP-independent. Nuclear protein kinase activities increased greater than two-fold, when expressed as units of activity per cell nucleus, during G1 phase traverse, concomitant with a 70% increase in nuclear non-histone proteins (those soluble in 0.6 M NaCl). This resulted in only a 40% increase in the specific activities (units/microgram protein in 0.6 M NaCl extractable nuclear fraction) of these enzymes as cells progressed through G1 into S phase. This was in contrast to cytoplasmic cyclic AMP-dependent protein kinase activities which also increased two-fold during progression through G1 phase while total cellular protein increased less than 20%. Activation of, as well as synthesis of, cyclic AMP-dependent cytoplasmic protein kinases during G1 phase suggests a regulatory mechanism for precise temporal phosphorylation, whereas the constant specific activity in nuclear kinases during cell cycle is more compatible with the maintenance of bulk phosphorylation processes in the nucleus.

Cell Cycle↗
PubMed1977

Clinical relevance of polyamines as biochemical markers of tumor kinetics.

The polyamines, spermidine and spermine, and their diamine precursor, putrescine, constitute a unidirectional biosynthetic pathway whose biosynthetic enzymes and accumulation patterns appear to play important roles in the regulation of growth processes. Concentrations of these compounds in physiological fluids are low or undetectable under normal conditions, are elevated in patients with metastatic cancer, and are thought to reflect growth (putrescine concentrations) and cell turnover (spermidine concentrations) of the organism. Cancers are a broad spectrum of diseases in which there are altered growth fractions and cell-turnover fractions, and therefore cancer chemotherapeutic agents have been developed to take tumor kinetics into account. Because changes in polyamines in physiological fluids reflect cell kinetics, this review compiles evidence of their efficacy as biochemical markers of cancer and suggests their possible usefulness to clinicians in rapidly assessing tumor response to chemotherapy or to multimodality therapy.

Animals↗
PubMed1977

Polyamines as markers of response and disease activity in cancer chemotherapy.

One hundred twenty-four patients with hematological and solid neoplasms had pretreatment urinary polyamine determinations. Putrescine, spermidine, and spermine were all significantly increased as compared to normals (p less than 0.001). Polyamine levels were directly related to disease activity and tumor burden. In patients with multiple myeloma, putrescine levels were significantly correlated with clinical disease activity as well as the in vitro labeling index of marrow plasma cells. Spermidine values reflected tumor cell burden. Serial studies in 56 patients indicated that greater than twofold rise in urinary spermidine during treatment was highly correlated with cell kill and subsequent clinical response (p less than 0.001). Serum polyamine levels in 17 patients were found to be comparable to urinary values. Our data indicate that polyamine determinations can potentially be clinically useful, i.e., baseline values as indicators of tumor cell mass and growth fraction, and increases in spermidine during treatment as an excellent marker of tumor cell kill.

Antineoplastic Agents↗
PubMed1977

Conjugation of radiolabeled polyamines in the rat.

Initial work reporting elevated polyamine levels in body fluids of cancer patients indicated that a percentage of the polyamine pools was present in conjugated form making hydrolysis necessary for assessment of the total polyamine content in urine and serum. In this paper, we report plasma decay curves for [14C]polyamines after i.v. administration and the temporal appearance of conjugates. Following the administration of [14C]polyamines, the radiolabel rapidly disappeared from the plasma in the order; spermidine greater than putrescine greater than spermine. Separation of the [14C]polyamines from conjugated radiolabeled compounds with Dowex chromatography indicated that [14C]putrescine and [14C]spermidine were rapidly conjugated, whereas no significant conjugation of spermine was detectable. After near-total hepatectomy of rats, there was no detectable formation of conjugates, whereas unilateral nephrectomy had little effect on the appearance of conjugates. This suggests that conjugation may take place in the liver. Free putrescine or spermidine could be regenerated from the conjugates by acid hydrolysis, suggesting that the conjugation process does not involve any alteration of the polyamines.

Animals↗
PubMed1977

The relationship between polyamine accumulation and DNA replication in synchronized Chinese hamster ovary cells after heat shock.

The relationship of polyamine accumulation and semiconservative DNA replication was studied in synchronous Chinese hamster ovary cultures, progressing through the cell cycle either normally at 37 degrees or after hyperthermic exposure (43 degrees for 1 hr) during G1 or S phase. In control cultures, intracellular polyamine levels decreased as cells divided and then reaccumulated as cells exited G1 and proceeded through the S and G2 phases. Immediately after cultures were exposed to 43 degrees heat for 1 hr in G1 phase, intracellular levels of spermidine and spermine were reduced compared to controls. Coordinate with the depletion of the intracellular levels of these polyamines following exposure at 43 degrees, extracellular levels of spermidine and spermine were increased. The ratio of intracellular to extracellular amounts of both these polyamines changed from 1 to 1.5 to approximately 0.2 to 0.3 after hyperthermic exposure. These cultures exposed to 43 degrees heat during G1 initially showed depressed levels of replicated DNA, but near-control rates of DNA replication were atained in a temporally related manner with the reaccumulation of intracellular spermidine and spermine levels. When cultures were exposed to 43 degrees heat in S phase, intracellular amounts of spermidine and spermine were again reduced and increased extracellular levels of these polyamines were observed. In these S-phase-treated cultures, cells were able to continue replicating their DNA but at a much reduced rate compared to controls. These results and other show that: (a) exposure of cells at 43 degrees causes a depletion of intracellular levels of spermidine and spermine, suggesting that an immediate aspect of thermal damage is a membrane defect that markedly affects the transport of these molecules across cell membranes; (b) exposure of either G1- or S-phase cultures to 43 degrees heat caused a depression of bulk DNA-synthetic rates resulting in a prolongation of S phase, and (c) the intracellular reaccumulation of spermidine and spermine following exposure of G1 cells to a 43 degrees heat shock is temporally related to the recovery of near-normal DNA synthetic rates in these cells.

Biological Transport↗
PubMed1976

Altered polyamine metabolism in the PRO/Re strain of inbred mice.

The PRO/Re strain of inbred mice are characterized by abnormally high concentrations of proline in both blood (hyperprolinaemia) and urine (prolinuria). They excrete increased amounts of polyamines in their urine. Male PRO/Re mice excreted putrescine at 175% and spermidine at 300% the amount of male C57BL/6J controls. Female PRO/Re mice excreted putrescine at 115% and spermidine at 150% of the amount in the urine of female controls. Examination of the enzymes involved in polyamine biosynthesis revealed that ornithine decarboxylase, the initial enzyme in the polyamine-biosynthetic pathway, was increased by 150% in the kidneys and by 100% in the liver of male PRO/Re mice. There was no significant difference between PRO/Re and C57BL/6J male mice for either putrescine- or spermidine-stimulated S-adenosylmethionine decarboxylase activity. Female PRO/Re mice showed no significant difference from female C57BL/6J mice for any of the enzymes examined. When the concentrations of the polyamines in the tissues of the PRO/Re mice were determined, spermidine and spermine concentrations in the kidneys of the male PRO/Re mice were twice those of the controls. Spermidine concentration in the livers of both male and female PRO/Re mice was approx. 130% that of the controls. Polyamine concentrations in the brains were similar in controls and mutants. The increased polyamine biosynthesis and excretion in the PRO/Re mutant mice may be a mechanism to decrease the extent of proline accumulation.

Adenosylmethionine Decarboxylase↗
PubMed1976

Cell cycle-specific activity of type I and type II cyclic adenosine 3':5'-monophosphate-dependent protein kinases in Chinese hamster ovary cells.

Types I and II cyclic adenosine 3':5'-monophosphate (cAMP)-dependent protein kinases have been studied during the cell cycle of Chinese hamster ovary cells. Chinese hamster ovary cells were synchronized by selective detachment of mitotic cells from monolayer cultures. Protein kinases were separated by DEAE-cellulose chromatography and were similar to the types of cAMP-dependent protein kinases studied in skeletal muscle and in heart extracts. The total amount of protein kinases activity per cell was substantial, both in mitosis and at the G1/S boundary. During mitosis, the relatively high activity of protein kinase was due to a predominance of type I protein kinase. During early G1, the activity of type I protein kinase decreased and there was little detectable type II activity. A rapid increase in the activity of type II was evident at the G1/S boundary. The administration of puromycin (50 mug/ml) from 1 to 5 hours after selective detachment of mitotic cells abolished the activity of type II cAMP-dependent protein kinase seen at the G1/S border, but had no observable effect on the activity of type I protein kinase. The data presented demonstrate cell cycle-specific activity patterns of type I and type II protein kinase Type I protein kinase activity is high in mitosis and is constant throughout the cell cycle. Increased type II protein kinase activity seems to be related to the initiation of DNA synthesis in S phase. The data suggest a translational control of type II cAMP-dependent protein kinase activity.

Cell Division↗
PubMed1976

G1 specific increases in cyclic AMP levels and protein kinase activity in Chinese hamster ovary cells.

Chinese hamster ovary cells were synchronized by selective detachment of cells in mitosis. The adenosine 3':5'-cyclic monophosphate (cyclic AMP) intracellular concentrations and cyclic AMP-dependent protein kinase activities were measured as these cells traversed G1 phase and entered S phase. Protein kinase activity, assayed in the presence or absence of saturating exogenous cyclic AMP in the reaction mixture, was lowest in early G1 phase (2 h after mitosis), increased 2-fold (plus exogenous cyclic AMP in reaction mixture) or 3.5-fold (minus cyclic AMP in reaction mixture) to maximum values in mid to late G1 phase (4-5 h after mitosis), and then decreased as cells entered S phase. Intracellular cyclic AMP concentrations were minimal 1 h after mitosis, increased 5-fold to maximum levels at 4-6 after mitosis, and decreased as cells entered S phase. Similar to the fluctuations in intracellular cyclic AMP, the cyclic AMP-dependent protein kinase activity ratio increased more than 40% in late G1 or early S phase. Puromycin (either 10 mug/ml or 50 mug/ml) administered 1 h after mitosis inhibited cyclic AMP-dependent protein kinase activity up to 50% by 5 h after mitosis, while similar treatment (10 mug/ml) had no effect on the increase in cyclic AMP formation. These data demonstrate that: (1) total protein kinase activity changed during G1 phase and this increase was dependent on new protein synthesis; (2) the increased intracellular concentrations of cyclic AMP were not dependent on new protein synthesis; and (3) the activation of cyclic AMP-dependent protein kinase was temporally coordinated with increased intracellular concentration of cycli AMP as Chinese hamster ovary cells traversed G1 phase and entered S phase. These results suggest that cyclic AMP acts during G1 phase to regulate the activation of cyclic AMP-dependent protein kinase.

Cell Line↗