Bone marrow disorders: characterization with quantitative MR imaging

Thirty patients with various hematologic disorders and 15 healthy control subjects underwent quantitative magnetic resonance (MR) imaging of the lumbar spine with spin-echo techniques. Images of patients with infiltrative bone marrow disorders showed significantly more prolonged T1 times than those of control subjects (P less than .001). It was not possible to distinguish different diffuse infiltrative bone marrow disorders on the basis of T1 values. Aplastic anemia could be distinguished from normality because of significantly shortened T1 (P less than .001). A significant correlation was seen between T1 and bone marrow cellularity (r = .74, P less than .001). T2 was of no value in the characterization of bone marrow disorders. Quantitative MR imaging dose not improve the diagnostic potential of bone marrow imaging in the detection of diffuse marrow infiltrates.     

Evaluation of ornithine decarboxylase activity as a marker for tumor growth rate in malignant tumors

Ornithine decarboxylase (ODC) is a rate-limiting enzyme in the synthesis of polyamines. Polyamines regulate DNA synthesis by a mechanism that is not fully understood. High levels of polyamines and ODC activity are associated with rapid cell growth, particularly in tumor tissues. The aim of this study was to determine whether ODC activity as a marker for rapid alterations in tumor growth could be used to investigate whether nutritional support in cancer patients stimulates tumor cell proliferation. Weight-losing head and neck cancer patients and tumor-bearing mice (MCG 101, C57/BL) were studied during different feeding regimens. The ODC activity in tumor tissue was investigated in relation to the following variables: (1) histopathologic differentiation; (2) DNA content; and (3) bromodeoxyuridine (BrdUrd) incorporation into DNA. After the animals were starved for 24 hours, a significant reduction of tumor growth was demonstrated in the experimental tumor along with a reduction of ODC activity, an accumulation of cells in the G0G1 phase, and a reduction of cells incorporating BrdUrd into DNA. Refeeding after 24 hours generated a response by all variables. Tumor biopsy specimens from patients with head and neck cancer malignancies demonstrated aneuploidy in the cells of 70% of the patients. High ODC activity in tumor tissue was demonstrated mainly among poorly differentiated tumors, and ODC activity was correlated with the compartment size of aneuploidic cells in the tumor. High ODC activity indicated a poor short-term survival (1 year). It was concluded that experimental tumor growth is highly dependent on host feeding. However, there was no evidence supporting the claim that nutritional support to cancer patients stimulates tumor cell proliferation. Determination of ODC activity may be used to monitor rapid changes in DNA synthesis and may have prognostic significance for survival.     

Effect of some metal compounds on the Ca2+ binding and Ca2+-Mg2+-ATPase activity of eggshell gland mucosa homogenate from the domestic fowl

Some metal ions, e.g. Hg2+, Cd2+ and Al3+, can have the effects as ecotoxicological agents, of causing eggshell thinning and breakage in birds. In a homogenate of the Ca2+-secreting part of the eggshell gland mucosa, a study was made of the influence of Hg2+, Cd2+, Cu2+, Pb2+, methyl-Hg+, Zn2+, V3+, Al3+ and Ni2+ in different concentrations on the rate of ATP-dependent 10(-4) M Ca2+ binding. All compounds had an inhibitory action. The most potent metal (Hg2+) produced 50% inhibition (IC50) at 1.1 X 10(-6) M, whereas this value for the least potent compound (Ni2+) was 9 X 10(-4) M. The specific Ca2+-Mg2+-ATPase activity was also inhibited by the tested metal ions. In all cases except methyl-Hg+ the IC50 for this activity was lower than that for Ca2+ binding. The most potent ion in this respect was Cd2+, with an IC50 of 8 X 10(-8) M, and the least potent was methyl-Hg+, with an IC50 of 1.4 X 10(-3) M. Pb2+ and Cd2+ in a concentration range of 10(-5)-10(-4) stimulated the Mg2+-ATPase activity, however, to almost the same extent as 10(-4) M Ca2+. A possible explanation for this effect is that these ions may have an affinity for sites of Ca2+ binding of the polypeptide calmodulin and thereby influence the Ca2+ metabolism of the shell gland mucosa.     

Glycerol dynamics in weight-losing cancer patients

This study was designed to show whether weight-losing cancer patients have an elevated glycerol turnover. Four groups of patients were examined: weight-losing cancer patients, weight-losing patients without cancer, cancer patients without weight loss, and weight-stable and well-nourished hospitalized control patients. Glycerol was infused intravenously at three different rates (200, 400, and 800 mumol/hr/kg body weight) after an overnight fast. This allowed measurement of clearance and plasma glycerol turnover. Weight-losing cancer patients (group 1) had an almost threefold higher glycerol turnover per kilogram of body weight compared with malnourished and well-nourished noncancer patients. However, both malnourished cancer and noncancer patients had an elevated glycerol turnover compared with well-nourished patients when glycerol turnover was related to whole body lipids. The results how that progressive clinical cancer is associated with an elevated plasma glycerol turnover, probably indicating an increased whole body lipolysis. This may explain the loss of body fat during the development of cancer cachexia.     

Protein synthesis in isolated human skeletal muscle tissue: evaluation of an experimental model.

Amino acids were incorporated into soluble proteins, myosin and myoglobin at constant rates for at least 4 h on incubation of isolated human skeletal muscle fibres. The time course of incorporation of leucine into proteins not attached to ribosomes was approximately constant, suggesting a continuous termination of proteins. A comparison between estimated pool size of ribosomes and incorporation rate of leucine into proteins indicated that initiation of peptides occurred even in the absence of insulin.