Uptake of 125I-iododeoxyuridine in mouse organs during deuteration of body water: Evidence for a thymus-specific effect

The effects of body water deuteration on mammalian DNA synthesis $\text{in vivo}$ during the deuterium equilibration period in the body were studied. Young adult mice were given 15% or 30% D₂O in the drinking water for 4, 10 or 21 days. Control mice were given distilled water. Eighteen hours prior to sacrifice, ¹²⁵IUdR, a conveniently monitored synthetic analogue of the DNA precursor thymidine, was injected intravenously. Although neither radioiodine activity of the total body nor body weight varied significantly among the three groups, thymic radioactivity per g tissue was significantly lower in mice given 30% D₂O and, to a lesser extent, in mice given 15% D₂O than in the control group. In contrast, intestine and hemopoietic bone marrow displayed minor changes in ¹²⁵IUdR incorporation. This reduction of ¹²⁵IUdR incorporation is discussed in relation to the particular importance of thymidine reutilization in the thymus.     

Evidence for phospholipid in plasma membrane penicillinase of Bacilluslicheniformis749C

The plasma membrane-bound penicillinase of $\text{Bacillus}$$\text{licheniformis}$$\text{749}\text{C}$ has been purified. Amino acid analysis showed no significant differences in composition between the enzyme and exopenicillinase. Enzyme purified from cultures containing H₃³³PO₄ or [³H]-glycerol contained ³³P or [³H]-glycerol activity and treatment with 8 M urea, 0.2% sodium dodecyl sulfate at 80° C did not remove the ³H-activity from the enzyme protein. Trypsin readily cleaved the glycerol-containing moiety from the enzyme protein, forming enzyme with molecular weight and heat stability like that of the exoenzyme. Phospholipase D and C also produced enzyme resembling the exo-form.     

Radioprotection by pretreatment with deuterated water: cytokinetic changes in the small intestine of the mouse

All mice partially deuterated by ingestion of 29% heavy water for 12 days survived whole body gamma irradiation (8.5 Gy) from a 60Co source, whereas 42% of nondeuterated control animals died from bone marrow failure. The incorporation of 3HTdR into enterocytic DNA, as measured by autoradiography and liquid scintillation spectrometry, was used to assess the proliferative activity of small intestinal epithelium. The sequence and the magnitude of changes in tritium activity were in good agreement. Deuteration alone resulted in a reduced proliferative activity of small intestinal crypt epithelium, particularly in the basal cell positions and the first positions of the proliferation compartment. The number of positions occupied by the proliferative compartment and the crypt length were, however, barely affected by deuteration. The radiation-induced depression of DNA synthesis in the proliferative compartment was of similar magnitude in both groups. Crypt epithelium in deuterated mice, however, displayed signs of an accelerated and/or enhanced regeneration. The cytokinetic changes in deuterated animals are consistent with a protective effect for clonogenic intestinal epithelium at the time of irradiation.     

The effect of folate and folate analogs upon dihydrofolate reductase and DNA synthesis in kidneys of normal mice

A single subcutaneous injection of folate, homofolate or MTX resulted in the inhibition of the activity of dihydrofolate reductase in homogenates prepared from the kidneys of normal mice. Stimulation of ³H-thymidine uptake occurred in the kidneys of treated animals approximately 30 hr after administration of either folate or homofolate, and reached a peak 72 hr after administration. The effects of folate and MTX on dihydrofolate reductase activity $\text{in}$$\text{vivo}$ were also determined. One hr after administration of 15 mg/kg methotrexate (MTX) or 300 mg/kg folate, enzyme activity $\text{in}$$\text{vivo}$ was inhibited by 90%.³H-deoxyuridine uptake was neither stimulated nor depressed after treatment with MTX. After administration of folate, uptake of ³H-deoxyuridine was stimulated at approximately 30 hr after drug-treatment and reached a peak at 72 hr after folate administration. Treatment with xanthopterin had no effect on the activity of dihydrofolate reductase $\text{in}$$\text{vitro}$. Xanthopterin stimulated uptake of both deoxyuridine and thymidine in an identical manner.The increased DNA synthesis that occurs in animals after treatment with agents that cause renal damage is distinct from the effect these agents have upon dihydrofolate reductase. Nucleoside incorporation after treatment with folate, homofolate, MTX or xanthopterin cannot be predicted on the basis of enzyme inhibition. Treatment with MTX, folate or homofolate results in enzyme inhibition which is not correlated with the uptake of deoxyuridine into DNA.     

Photoaffinity labelling with an ATP analog of the N-terminal peptide of myosin.

Photoaffinity labelling of tryptic and chymotryptic heavy meromyosin with 3′O-3-[N-(4-azido-2-nitrophenyl) amino]propionyl-adenosine 5′-triphosphate (arylazido-β-alanine ATP) resulted in incorporation of radioactivity and inhibition of the ATPase activity. ATP prevented the reaction with the photoaffinity label, as shown by the lack of incorporation of ³H and intact ATPase activity. On the tryptic digestion of either type of photoaffinity labeled HMM the label was found in a 25K peptide identifiable with the N-terminus of the myosin heavy chain (Lu et al., Fed. Proc. $\text{37}$ 1695 1978). The results are discussed in the light of previous localization of the reactive thiol groups, SH-1 and SH-2 (Balint et al., Arch. Biochem. Biophys. $\text{190}$, 793 1978).     

Transfer of phospholipids between the endoplasmic reticulum and mitochondria in rat hepatocytes in vivo

The transfer of phospholipids from the endoplasmic reticulum to the inner mitochondrial membrane was investigated by pulse labeling $\text{in}\text{vivo}$. With [³H]glycerol microsomal phosphatidylethanolamine and phosphatidylcholine were rapidly labeled during the first 30 min; while maximum incorporation into the inner mitochondrial membrane occurred only after about 5 hours. It appears that the $\text{in}\text{vivo}$ transfer of these phospholipids between the two membrane compartments is a relatively slow process.     

2H- and 31P-NMR studies of bilayers composed of 1-acyllysophosphatidylcholine and fatty acids

1-Palmitoyllysophosphatidylcholine has been mixed in equimolar amounts with specifically deuterated palmitic acid and the structural properties of the lipid/water phase have been studied by ²H- and ³¹P-nuclear magnetic resonance. The order profile of the free palmitic acid is very similar to that of the parent compound $\text{1,2-}\text{dipalmitoyl}\text{-sn-}\text{glycero-3-phosphocholine}$ at temperatures above the gel-to-liquid crystal phase transition. The bending of the $\text{sn-2}$ chain which is typical for diacyl lipids is not observed for the free palmitic acid. The mixture of lysolipid and palmitic acid exhibits well-defined quadrupole splittings even at temperatures below the gel-to-liquid crystal phase transition. Hence it is possible for the first time to establish an order profile in the gel-state of the lipid bilayer phase. Between carbon atoms 5 to 12 the palmitic acid chain is found to assume the extended all-trans conformation with a very small contribution from gauche defects. Towards the methyl terminal a distinct increase in the gauche probability can be noted. The motion of the phosphocholine headgroup was also studied by ²H- and ³¹P-NMR using selectively deuterated 1-palmitoyllysophosphatidylcholine. The headgroup has a considerably larger motional freedom in the mixture of lysolipid and palmitic acid than in $\text{1,2-}\text{dipalmitoyl}\text{-sn-}\text{glycero-3-phosphocholine}$. In addition, the average headgroup conformations are also different in the two systems.     

Does dehydration contribute to retarded fetal growth in rats exposed to alcohol during gestation?

An earlier study showed that pregnant rats given ethanol in drinking water exhibited a significant degree of dehydration. The objective of the present study was to determine whether dehydration alone contributes to fetal growth retardation in alcohol treated rats. Female Sprague-Dawley rats were divided into 4 dietary groups. Group 1 (alcohol) received 20% ethanol in drinking water for four weeks prior to mating and 30% alcohol in drinking water throughout pregnancy and a stock diet $\text{ad libitum}$. Group 2 (pair-fed) was given an amount of food equal to that consumed by the alcohol group with the alcohol isocalorically substituted by corn starch. Water was available $\text{ad libitum}$. Group 3 (pair-water) was given an amount of food and water equal to that consumed by the alcohol animals. Group 4 ($\text{ad libitum}$) was given food and water $\text{ad libitum}$. On day 21 of gestation body weights of the alcohol exposed fetuses were significantly lower than those of the other three treatment groups. The difference in fetal body weights between the pair-fed and pair-water groups was not significant. Placentas were significantly heavier in the alcohol group than in the pair-fed and pair-water groups. Maternal plasma osmolality was significantly higher in the alcohol treated rats when compared to the pair-fed and $\text{ad libitum}$ controls but not the pair-water group. No significant differences were seen in fetal plasma osmolality among the four treatment groups. It is concluded that dehydration does not contribute significantly to retarded fetal growth in rats given alcohol in drinking water as the sole source of fluid prior to and during gestation.     

Bilayers of dipalmitoyl-3-sn-phosphatidylcholine: Conformational differences between the fatty acyl chains

$\text{Dipalmitoyl}\text{-3-sn-}\text{phosphatidylcholine}$ is specifically deuterated at the C-2 position of the fatty acyl chains. Using deuterium magnetic resonance it is then possible to probe the chain conformation in the vicinity the polar head groups. Three separate quadrupole splittings are observed for bilayers of 1,2[2′-²H₂] $\text{palmitoyl}\text{-3-sn-}\text{phosphatidylcholine}$, indicating that the two chains behave differently. The synthesis of phosphatidylcholines each deuterated in only one chain allows the assignment of the three resonances. It is concluded that the beginnings of the two chains have orientations parallel and perpendicular to the bilayer normal. The data further suggest the possibility of two long-lived conformations of the glycerol constituent.     

Differing responses of inbred rat strains in experimental autoimmune thyrioditis.

The CMI response in vitro and in vivo of 30 patients with a poor biologic response to infection with C. immitis was investigated. In patients with active pulmonary disease, skin reactivity to CDN was observed in $\text{7}\text{10}$, and to at least one of five other antigens in $\text{8}\text{10}$. In patients with the most extensive infection, disseminated disease, skin reactivity to CDN and to at least one of five other antigens was observed in only $\text{4}\text{8}$. In patients with inactive disease, skin reactivity to CDN and to at least one of five other antigens was observed in $\text{11}\text{12}$. Even when skin reactivity to CDN was present, MIF release and, more frequently, ³H-thymidine incorporation were not consistently stimulated by CDN. Maximal ³H-thymidine incorporation in response to PHA and CDN is delayed in 50% of the patients studied. The defect also may be present in patients with inactive disease; however, in two patients followed serially, lymphocyte function very slowly returned to normal. Rosette-forming cells were normal in $\text{18}\text{30}$.The frequency with which patients with coccidioidal disease demonstrate a defect in cell-mediated immunity raises unanswered questions about the mechanisms responsible for the defect and the role it may play in the biologic defense against invasion by this fungus.     

Proton relaxation study of molecular motions in low density lipoproteins

Molecular motion and molecular organization of human serum low-density lipoprotein (LDL) has been studied in the temperature range ? 30 to 30°C by proton magnetic relaxation. LDL in deuterated Tris-HCl buffer exhibit two mobile phases. The slow-relaxing phase ($\text{T}{}_1\text{? 1.5 s}$) is assigned to the incompletely deuterated water of the buffer, and the fast-relaxing phase ($\text{T}{}_1\text{? 60 ms}$) to the fatty acid chains of the lipoprotein core. It has been established that there is a correlation between the state of the outer surface and the interior of the LDL particle: the number of fast-relaxing protons is significantly altered by cooling the system through the freezing point of the buffer or by selecting buffers of different ionic strengths. At room temperature, ～ 30% of the lipid protons of LDL in the 0.1 m buffer and ～ 40% of the lipid protons of LDL in the 0.01 m buffer relax quickly within the time-scale of n.m.r. frequency (24 MHz).     

Effects of 3′-deoxyadenosine triphosphate on in vitro RNA synthesis of plant RNA-dependent RNA polymerases

3′-deoxyadenosine triphosphate inhibited $\text{in}\text{vitro}$ [³H]UMP incorporation by RNA-dependent RNA polymerases from tobacco and cowpea plants. The inhibition of [³H]UMP incorporation could be reversed by simultaneous addition of higher ATP concentrations but not with increasing concentrations of UTP or when excess ATP was added 10 min after the inhibitor. These results suggest 3′-deoxyadenosine triphosphate competes specifically with ATP in reaction mixtures and results in premature termination of RNA synthesis $\text{in}\text{vitro}$ by RNA-dependent RNA polymerase.     

Inhibitor of heme synthesis in polycythemic rabbit serum

Sera from hypertransfused polycythemic rabbits were found to significantly inhibit ⁵⁹Fe incorporation into heme in erythroid cells in normal rabbit bone marrow cultures when compared with that of normal serum controls suggesting a higher concentration of this inhibitor in polycythemic serum. This serum inhibitor delayed the time of peak cumulative heme synthesis $\text{in}$$\text{vitro}$ and the delay in peak cumulative heme synthesis was increase with increasing concentrations of polycythemic serum. It is suggested from these studies that this serum inhibitor may be involved in a negative feedback system in the control of erythropoiesis and may act specifically on differentiated nucleated erythroid cells to delay their entry into the cell cycle, consequently inhibiting heme synthesis.     

The biosynthesis of lubimin from [1-14C]isopentenyl pyrophosphate by cell-free extracts of potato tuber tissue inoculated with an elicitor preparation from Phytophthora infestans

A cell-free enzyme system, which catalyses the incorporation of radiolabel from [$\text{1}\text{2}$-¹⁴C]isopentenyl pyrophosphate into the sesquiterpenoid phytoalexin lubimin, has been prepared from tuber tissue of Solanum tuberosum inoculated with an elicitor preparation from Phytophthora infestans. Biosynthesis of lubimin is optimum at pH 7.$\text{3}\text{2}$-7.5 and is dependent upon Mg²⁺ and NADPH. Lubimin labelling by cell-free enzyme system prepared from tissue 48 hr after treatment with elicitor rises rapidly to a maximum over the first 30 min of incubation and does not decline for a further 150 min. The biosynthetic capacity for lubimin in cell free extracts can be observed as early as 3 hr after inoculation of tuber tissue, and rises to a maximum at about 48 hr after treatment, declining thereafter. Lubimin labelling is inhibited by iodoacetamide, the effect of which is reversed by 3,3-dimethylallylpyrophosphate. Preliminary observations on the cell-free system show that it will also catalyse the incorporation of [2-¹⁴C]mevalonic acid into lubimin in the presence ofan ATP-generating system.     

Defect in 3'-phosphoadenosine 5'-phosphosulfate synthesis in brachymorphic mice. II. Tissue distribution of the defect

The tissue distribution of the defective PAPS synthetic pathway in homozygous brachymorphic mice ($\text{bm}\text{bm}$) has been investigated using four different criteria: (i) incorporation of ³⁵SO₄^2? into adenosine 5′-phosphosulfate (APS), 3′-phosphoadenosine 5′-phosphosulfate (PAPS), and endogenous macromolecular acceptors, (ii) APS kinase (adenylylsulfate kinase; ATP:adenylylsulfate 3′-phosphotransferase, EC 2.7.1.25) activity, (iii) ATP sulfurylase (sulfate adenylyltransferase; ATP:sulfate adenylyltransferase, EC 2.7.7.4) activity, (iv) thermostability of ATP sulfurylase. With respect to the first three criteria, the results indicate that liver is affected as profoundly as cartilage (K. Sugahara and N. B. Schwartz, Arch. Biochem. Biophys. (1982) 214, 589–601). In contrast, skin and brain show no differences between normal and mutant. Kidney is significantly, but only moderately, affected. The results from thermostability studies demonstrate that ATP sulfurylase activity is more labile in $\text{bm}\text{bm}$ cartilage, liver, and kidney, but not in skin or brain, supporting the above-observed distribution of the defect. Therefore, the present results indicate a multiple, but not universal, tissue distribution of the defective PAPS synthetic pathway in $\text{bm}\text{bm}$ mice. Furthermore, these findings support the suggestion that ATP sulfurylase as well as APS kinase is defective in brachymorphic mice.     

Growth inhibition of clonal osteosarcoma cell-lines by low concentrations of glucocorticoid hormones

Clonal osteosarcoma cell line, ROS $\text{2}\text{3}$, showed marked inhibition of [³H]thymidine incorporation in response to low concentrations (10^?10 M) of triamcinolone acetonide and dexamethasone. Hydrocortisone and corticosterone induced inhibition at somewhat higher concentrations. The osteosarcoma cell line ROS $\text{17}\text{2}$ responded similarly to triamcinolone acetonide and dexamethasone but at higher concentrations of the hormones. In ROS $\text{2}\text{3}$ the inhibitory effects of triamcinolone acetonide were accompanied by only slight elevation in the amount of intracellular exchangeable Ca²⁺. In contrast, in primary cultures of normal rat-calvarian bone cells, [³H]thymidine incorporation was inhibited to a much lesser extent only at higher concentrations of triamcinolone acetonide (10^?7 M). The difference in the susceptibility of normal and malignant bone cells to the inhibitory effects of glucocorticoids may have potential therapeutic importance.     

Acyltransferases and the biosynthesis of pulmonary surfactant lipid in adenoma alveolar type II cells.

Acyltransferases are present in microsomes from alveolar type II cell adenomas (produced by urethan injections) that transfer palmitic acid in the presence of CoA, ATP, and Mg⁺⁺ to $\text{sn}$-glycerol-3-P to form phosphatidic acid, to dihydroxyacetone-P to form acyldihydroxyacetone-P, and to 1-acyl-$\text{sn}$-glycero-3-phosphocholine to form 3-$\text{sn}$-phosphatidylcholine. The data clearly demonstrate that the microsomal preparations can catalyze significant incorporation of palmitic acid into the 2-position of the disaturated species of 3-sn-phosphatidylcholine independently of phosphatidic acid formation as evidenced by the fact that $\text{sn}$-glycerol-3-P and calcium ions (which inhibit choline phosphotransferase) did not influence the incorporation of palmitic acid into the main surfactant lipid. Thus, a deacylation-acylation reaction involving 2-lysophosphatidylcholine appears to be an important pathway for the synthesis of surfactant lipid in alveolar type II cells; the control of acyl specificity at the 2-position is determined by the relative concentrations of the coparticipating substrates, l-palmitoyl-$\text{sn}$-glycero-3-phosphocholine and palmitoyl-CoA.     

Effects of norepinephrine and acetylcholine on 32P incorporation into phospholipids of the rabbit iris muscle following unilateral superior cervical ganglionectomy.

The effect of norepinephrine and acetylcholine on the ³²P incorporation into phospholipids of normal and sympathetically denervated rabbit iris muscle was investigated. (1) In the absence of exogenously added neurotransmitters sympathetic denervation exerted little effect on the incorporation of ³²P into the phospholipids of the excised iris muscle. $\text{In vivo}$ thr iris muscle incorporated ³²P into phosphatidylinositol, phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and sphingomyelin in that order of activity while $\text{in vitro}$ phosphatidylinositol was followed by phosphatidylcholine. (2) Tension responses of iris dilator muscle from denervated irises exhibited supersensitivity to norepinephrine. Furthermore, norepinephrine at concentrations of 3 μM and 30 μM produced 1.6 times and 3 times stimulation of the phosphatidic acid of the denervated muscle respectively. In contrast at 30 μM it stimulated this phospholipid by 1.6 times in the normal muscle. This stimulation was completely blocked by phentolamine. (3) While in the normal muscle acetylcholine stimulated the labelling of phosphatidic acid and phosphatidylinositol by more than 2 times, in the denervated muscle it only stimulated 1.4 to 1.7 times. (4) Similarly when ³²Pi was administered intracamerally, the labelling found in the various phospholipids of the denervated iris was significantly lower than that of the normal. (5) It was concluded that denervation decreases the ³²P labelling in the presence of acetylcholine. (6) The norepinephrine-stimulated ³²P incorporation into phosphatidic acid appears to be post-synaptic.     

Placental blood flow in rats fed alcohol before and during gestation

Female Sprague-Dawley rats were either given 20% alcohol in drinking water and solid diet $\text{ad libitum}$ (alcohol group) or were pair-fed to the alcohol group (pair-fed group) or were given water and solid diet $\text{ad libitum (ad libitum}$ group) for four weeks. They were then mated and the alcohol group was changed to 30% alcohol in water. On day 20 of gestation each rat was injected with ⁵⁷Co-labeled microspheres into the left ventricle and radioactivity was determined in the placentas and kidneys. Cardiac output and blood flow to the placentas and kidneys was calculated. Fetuses and placentas were weighed, and the osmolality of the maternal plasma and water content of the muscle was determined. Cardiac output and blood flow to the kidneys did not differ among the three groups. Blood flow to the placenta, whether expressed as m1/min/g placenta or m1/min/placenta, or as % of cardiac output was significantly reduced in the alcohol group compared with the pair-fed and $\text{ad libitum}$ groups, which did not differ from one another. Fetuses were significantly lighter and placentas were significantly heavier in the alcohol group than in the other two groups. Plasma osmolality was increased and muscle water was decreased about 7% in the alcohol group, indicating a moderate degree of dehydration. It is concluded that chronic alcohol consumption leads to a redistribution of blood, with less blood supplying the placentas. This may contribute to the growth retardation seen in fetal alcohol syndrome.     

Changes in structural integrity of heart DNA from aging mice

The state of the structural integrity of the DNA from mouse myocardial cells has been investigated by utilizing both CsCl density gradient sedimentation and digestion by S₁ endonuclease from $\text{Aspergillus}$$\text{orzae}$. The DNA from myocardial cells of young mice sedimented in a narrow peak at the expected density of 1.701 g/cm³, while the DNA from the heart cells of senescent mice became broadly distributed in CsCl gradients, banding even more multimodally in alkaline sucrose gradients. This mode of sedimentation indicates that old mouse DNA becomes partially fragmented. When the native DNA of myocardial cells from 6, 20 and 30 month old mice was treated with single-strand specific S₁ endonuclease, it was the DNA from the senescent mice that showed a progressive increase in sensitivity to digestion by the enzyme. The results indicate that the heart DNA of aging mice develops single-stranded gaps in addition to a breakdown into differently sized fragments.