Neoplastic development: paradoxical relation between impaired cell growth at low population density and excessive growth at high density.

The role of heritable, population-wide cell damage in neoplastic development was studied in the 28 L subline of NIH 3T3 cells. These cells differ from the 17(3c) subline used previously for such studies in their lower frequency of "spontaneous" transformation at high population density and their greater capacity to produce large, dense transformed foci. Three cultures of the 28 L subline of NIH 3T3 cells were held under the constraint of confluence for 5 wk (5 wk 1 degree assay) and then assayed twice in succession (2 degrees and 3 degrees assays) for transformed foci and saturation density. After the 2 degrees assay, the cells were also passaged at low density to determine their exponential growth rates and cloned to determine the size and morphological features of the colonies. Concurrent measurements were made in each case with control cells that had been kept only in frequent low-density passages and cells that had been kept at confluence for only 2 wk (2 wk 1 degree). Two of the three cultures transferred from the 2 degrees assay of the 5 wk 1 degree cultures produced light transformed foci, and the third produced dense foci. The light focus-forming cultures grew to twice the control saturation density in their 2 degrees assay and 6-8 times the control density in the 3 degrees assay; saturation densities for the dense focus formers were about 10 times the control values in both assays. All three of the cultures transferred from the 2 degrees assay of the 5 wk 1 degree cultures multiplied at lower rates than controls at low densities, but the dense focus formers multiplied faster than the light focus formers. The reduced rates of multiplication of the light focus formers persisted for > 50 generations of exponential multiplication at low densities. Isolated colonies formed from single cells of the light focus formers were of a lower population density than controls; colonies formed by the dense focus formers were slightly denser than the controls but occupied only half the area. A much higher proportion of the colonies from the 5 wk 1 degree cultures than the controls consisted of giant cells or mixtures of giant and normal-appearing cells. The results reinforce the previous conclusion that the early increases in saturation density and light focus formation are associated with, and perhaps caused by, heritable, population-wide damage to cells that is essentially epigenetic in nature. The more advanced transformation characterized by large increases in saturation density and dense focus formation could have originated from rare genetic changes, such as chromosome rearrangements, known to occur at an elevated frequency in cells destabilized by antecedent cellular damage.     

The changes of growth activities in pituitaries of tadpoles at different metamorphic stages.

In order to evaluate growth activities in tadpoles of various metamorphic stages, pituitaries taken from metamorphosing tadpoles of Rana catesbeiana were homografted into hypophysectomized (Hx) and thyroidectomized (Tx) host tadpoles. Parameters such as body weight, total length, water content, dry matter, and tail height of the host tadpoles were used for determining growth activities. All of these five parameters increased after grafting, when compared with the Hx and Tx controls. The percentage increment was greatest in pituitaries from premetamorphic tadpoles and least in pituitaries from climactic tadpoles and froglets while that of prometamorphic tadpoles was intermediate. The tendency of the decrease of growth activities in the hosts according to the progress of metamorphosis of the donor tadpoles seemed to be reciprocal to the development of thyroid activity. These growth activities appeared to be related to the grafted pituitaries which are believed to contain a growth factor comparable to mammalian prolactin.     

Nonmammalian growth hormones have diabetogenic and insulin-like activities

Purified GHs isolated from ostrich, sea turtle, snapping turtle, bullfrog, Tilapia, and sturgeon were tested for in vivo diabetogenic activity in the hereditarily obese ob/ob mouse and for in vitro insulin-like activity in isolated adipose tissue from hypophysectomized rats. GHs from all species exhibited significant diabetogenic activity, causing fasting hyperglycemia and decreased glucose tolerance when administered at doses of 100 micrograms/day (ostrich, bullfrog, and sturgeon) or 200 micrograms/day (sea turtle, snapping turtle, and Tilapia) for 3 days. Similar responses were obtained when purified human GH was administered at a dose of 10 micrograms/day for 3 days. GHs from most species also exhibited significant insulin-like activity, stimulating increased [14 C]glucose oxidation to 14CO2 by isolated adipose tissue from hypophysectomized rats when employed at concentrations of 50 nM (bullfrog), 250 nM (sturgeon), 500 nM (ostrich), or 2500 nM (sea turtle and Tilapia). Purified human GH gave similar responses at concentrations of 2.5-5 nM in this assay. These results support the hypothesis that diabetogenic and insulin-like activities are intrinsic properties of GH and provide strong evidence that the structural determinants for diabetogenic and insulin-like activities arose early in the evolution of the GH molecule.     

Daily activities and survival at older ages

OBJECTIVE: This study tested the hypothesis that time spent on activities that are considered regenerative (e.g., resting), productive (e.g., housework), and consumptive (e.g., meeting friends) is associated with survival in persons aged 70 and older. METHODS: An observational study with mortality follow-ups was carried out in the former West Berlin, Germany. The sample was stratified by age and sex, and it consisted of 473 persons aged 70 to 103 years. Study participants lived in the community as well as in institutions. Activity measures were assessed from 1990 to 1993 by structured interviews in the participants' homes. Cox regression was used to model survival from time of interview. The main outcome measure was survival on August 1, 2003. RESULTS: Consumptive activities were related to survival (relative risk = 0.89, 95% confidence interval 0.83 to 0.97), after several confounding factors were controlled for. The effect diminished over time. DISCUSSION: Results support the idea that daily activities are linked to survival via a psychosocial pathway that might involve perceived quality of life. Consumptive activities (e.g., meeting friends, reading a novel) may contribute considerably to maintaining health and achieving longevity because they are performed on a daily basis and their effects may accumulate over the life course.     

Biologic activities of growth hormone secretagogues in humans

Growth hormone secretagogues (GHSs) are synthetic peptidyl and nonpeptidyl molecules with strong, dose-dependent, and reproducible growth hormone (GH)-releasing activity even after oral administration. GHSs release GH via actions on specific receptors (GHS-R) at the pituitary and, mainly, at the hypothalamic levels. GHSs likely act as functional somatostatin antagonists and meantime enhance the activity of GH-releasing hormone (GHRH)-secreting neurons. The GH-releasing effect of GHSs is independent of gender but undergoes marked age-related variations. Estrogens play a major role in enhancing the GH response to GHSs at puberty, which GHRH hypoactivity, somatostatinergic hyperactivity and impaired activity of the putative GHS-like ligand and receptors probably explain the reduced GH-releasing effect of GHSs in aging. The activity of GHSs is not fully specific for GH. Their slight prolactin-releasing activity probably comes from direct pituitary action. In physiological conditions, the ACTH-releasing activity of GHSs is dependent on central actions; a direct action on GHS-R in pituitary ACTH-secreting tumors likely explains the peculiar ACTH and cortisol hyperresponsiveness to GHSs in Cushing disease. GHSs have specific receptor subtypes in other central and peripheral endocrine and nonendocrine tissues mediating GH-independent biologic activities. GHSs influence sleep pattern, stimulated food intake, and have cardiovascular activities. GHs have specific binding in normal and neoplastic follicular derived human thyroid tissue and inhibit the proliferation of follicular-derived neoplastic cell lines. The discovery of ghrelin, a 28 amino acid peptide synthesized in the stomach but also in other tissues, has opened new fascinating perspectives of research in this field.     

Hemoblastoses in mice contaminated with low activities of 239Pu

Female ICR mice were injected intravenously with low activities of 239Pu (3.0 kBq, 6.0 kBq, 12.3 kBq/kg). In these mice with high spontaneous incidence of hemoblastoses the occurrence of myeloid leukemia, lymphocytic leukemia, lymphosarcoma, reticulum-cell sarcomas and osteosarcoma was studied. Hemoblastoses, on the whole, remained in their numbers radiation-independent, nevertheless, the distribution into specific types changed, with moderate prevalence of myeloid and lymphocytic leukemia and lymphosarcoma. After plutonium injection the mean survival time of mice bearing myeloid and lymphocytic neoplasias was significantly shorter than the survival of mice that died of retothelosarcoma and from other causes. These contamination-dependent differences could not be observed in matched controls. As expected, 239Pu activities used in this experiment induced osteosarcomas. Whereas in leukemogenesis alpha-radiation appeared as a factor promoting and modifying the leukemogenic process, in osteosarcoma the alpha-particles acted rather as an initiator, the effect of which was dependent on the dose to the endosteal progenitor cells.     

Skeletal muscle function at low work level as a model for daily activities in patients with chronic heart failure

AIM: Metabolic exercise abnormalities have been reported in chronicheart failure patients. This study sought to evaluate whetherthese abnormalities affected daily activity. METHODS AND RESULTS: In 16 patients with moderate-to-severe chronic heart failureand in eight controls we measured femoral flow (thermodilution)and metabolism (glucose, lactate, free fatty acids, blood gasvalues) at rest and during a constant load of 20 W, which maymimic a daily activity. At rest, chronic heart failure patientshad a leg flow similar to controls, but showed a higher legoxygen consumption (4·6±0· vs 2·6±0·4ml. min^–1; P>0·05), a higher arteriovenous oxygendifference (7·2±0·5 vs 5·4±0·7ml . d1^–1; P>0·05), and a lower femoral veinpH (7·37±5·–03 vs 7·42±0·01;P=0·01). At 20 W, chronic heart failure patients hada leg flow similar to controls, but showed increased lactaterelease (from resting 11·7±33 to 142+125 µg. min^–1 P>0·0001 vs controls, from resting 5·7±15·4to 50±149 µg . min^–1 ns), higher arterialconcentration of free fatty acids (781±69 vs 481±85µmol . 1^–1; P>0·01), lower femoral veinHCO₃ (24·1+2·6 vs 26·3±1·7mmol .1^–1;P>0·05) and base excess (–2·3+2·3vs –0·24±1·7 mmol . 1^–1 P=0·01 CONCLUSION: In chronic heart failure patients, the important cellular metabolicalterations already present at rest partially affect daily activities,owing to a further decrease in the efficiency of muscle metabolicprocesses, and may preclude tolerance of heavier activities.Such alterations appear, at least in part, independent of peripheralhaemodynamic responses to exercise.     

Lysosomal enzyme activities and low density lipoprotein receptors in circulating mononuclear cells

Summary Methods for the measurement of the lysosomal enzymes acid cholesterol-ester hydrolase and N-acetyl--glucosaminidase were adapted for use with freshly isolated circulating mononuclear cells. Activities of both these enzymes increased (to 259 and 147% of control values respectively) after 7 days of insulin therapy in diabetic subjects. Low density lipoprotein degradation by freshly isolated mononuclear cells increased simultaneously by 67% (p< 0.05). The findings in this pilot study suggest [1] that circulating mononuclear cells can be used to evaluate the effect of metabolic changes in vivo on lysosomal enzymes and low density lipoprotein metabolism, and [2] that insulin can stimulate cellular lysosomal enzyme activity.     

Macrophages possess both neutral and acidic protease activities toward low density lipoproteins

Low density lipoproteins (LDL) have been strongly implicated in the pathogenesis of atherosclerosis. We have studied the proteolytic degradation of these lipoproteins by macrophages, which are a major cellular constituent of atherosclerotic lesions. Mouse peritoneal macrophages contained both an acidic and a less active but distinct neutral/alkaline protease activity toward human 125I-labelled LDL. The acidic activity had a pH optimum of 4.5 and the neutral/alkaline activity one of 8-8.5. The acidic activity started to plateau with increasing lipoprotein concentrations whereas the neutral activity was directly proportional to the lipoprotein concentration up to at least 150 micrograms of protein/ml. The acidic protease activity had a complex time course whereas the neutral activity was directly proportional to the time of incubation up to at least 48 h. Leupeptin (35 microM) and pepstatin (5 microM) inhibited the acidic activity by about 70% individually and almost entirely in combination, indicating that cathepsins B and D are important in the degradation of LDL by lysosomal cathepsins. In contrast, there was little, if any, inhibition of the neutral protease activity by leupeptin or pepstatin. The acidic protease activity was increased by both DL-dithiothreitol (5 mM) and disodium EDTA (1 mM) whereas the neutral protease activity was increased by dithiothreitol but inhibited partially by EDTA. The possible significance of macrophage neutral and acidic protease activities toward LDL in atherosclerosis needs to be assessed.     

介绍一种低碘水,粮微量碘测定方法

本文介绍了澳大利亚人类营养研究所(CSIRO)采用的粮食碘测定方法;并对该方法加以部分改进;用浓 HCl 代替稀 HCl 配制亚砷酸钠可提高灵敏度;同时评价了该方法的灵敏度、准确度及精密度。在我室条件下测定的 K 值为1.37±0.016SEM。我们认为该方法适合于病区低碘水、粮样品碘的测定。     

Vascular endothelial growth factor activities on osteoarthritic chondrocytes

OBJECTIVE: Evaluation of the role of VEGF in cartilage pathophysiology. METHODS: VEGF release from chondrocytes in the presence of IL-1beta, TGFbeta and IL-10 was detected by immunoassay. VEGF receptor -1 and -2 expression and VEGF ability to modulate caspase -3 and cathepsin B expression were detected by immunohistochemistry on cartilage biopsies and cartilage explants. VEGF effects on chondrocyte proliferation was analysed by a fluorescent dye that binds nucleic acids. RESULTS: VEGF production by osteoartritis (OA) chondrocytes was significantly reduced by IL-1beta while it was increased in the presence of TGFbeta. Cartilage VEGFR-1 immunostaining was significantly downregulated in 'early' OA patients compared to normal controls (NC). VEGFR-2 expression was negligible both in OA and in NC. VEGF decreased the expression of caspase-3 and cathepsin B, whereas it did not affect proliferation. CONCLUSION: VEGF is able to down-modulate chondrocyte activities related to catabolic events involved in OA cartilage degradation.     

Challenges in the development of platelet growth factors: low expectations for low counts

Thrombocytopenia remains a significant clinical problem for which only symptomatic therapy, namely platelet transfusion, is available for management of acute events. Platelet transfusions are often complicated by febrile reactions, as well as the risk of transmission of infectious agents and the likelihood of alloimmunization, which then decreases the effectiveness of additional transfusion support. The availability of a hematopoietic cytokine that could reliably stimulate platelet recovery, analogous to the effect of granulocyte colony-stimulating factor on neutrophil recovery following chemotherapy, would greatly enhance supportive care in cancer and provide an effective therapy for a variety of diseases that cause thrombocytopenia. To identify such a thrombopoietic cytokine, studies initially focused on regulatory molecules that stimulates early multipotent hematopoietic progenitors, such as interleukin-1 and interleukin-6. Unfortunately, these cytokines had poor efficacy and significant toxicity in human testing. Recombinant human interleukin-11, an early-acting cytokine, has modest efficacy and clinically challenging toxicities, but in the absence of other active drugs, it has been licensed for prevention of severe chemotherapy-induced thrombocytopenia. Recent interest has focused on analogs of thrombopoietin, the endogenous regulator of thrombopoiesis, which have the potential for much greater efficacy with minimal toxicity due to the more specific targeting of megakaryocyte-specific signaling.