Standardization of papain reagents by measurement of active sites using a synthetic inhibitor, E-64

L-trans-epoxysuccinyl-leucylamido (4-guanidino) butane (E-64) reacts rapidly and irreversibly in a one-to-one ratio with the active site of papain, causing complete inhibition of the enzyme. After the addition of various concentrations of E-64 to a papain preparation, the residual enzyme activity can be measured using an azoprotein technique. The molarity of E-64 required to cause complete inhibition of papain activity is equal to the molarity of papain-active sites. Preparations of papain from various sources were assayed for protease activity by hydrolysis of azoalbumin using several variants of the basic technique and also by hydrolysis of azocasein. For each variant of azoprotein assay procedure, the active sites of the papain were measured using E-64. All variations of the azoprotein technique yielded similar estimates of the active site molarity of the papain preparations, whereas the azoprotein assay results alone showed wide variation. Quantitation of the active-site molarity of various papain preparations using E-64 correlated with serologic efficacy.

Indirect induction of radiation lymphomas in mice. Evidence for a novel, transmissible leukemogen

The transmission of a lymphomagenic agent(s) from the bone marrow of irradiated mice to thymic target cells has been demonstrated by: (a) the induction of T cell lymphomas in nonirradiated thymic grafts implanted in irradiated, Thy-l-congenic mice, (b) the induction of T cell lymphomas of host origin in mice infused with bone marrow from irradiated, Thy-l-congenic donors. The latter procedure also yields an appreciable number of pre-B cell lymphomas of uncertain origin. The results confirm Kaplan's theory that radiation induces thymic lymphomas in mice by an indirect mechanism. However, the previously described radiation leukemia virus is clearly not involved in the majority of transferred lymphomas. We propose that the mediating agent in radiation lymphomagenesis is a novel, transmissible agent induced in the bone marrow, but exerting its transforming activity on cells in the thymus. The nature and mode of action of the agent are under investigation.

The pH optima for papain and bromelain treatment of red cells

The action of papain and bromelain, prepared over a pH range from 4.6 to 8.6, was evaluated for the ability to render red cells agglutinable by five incomplete antibodies of differing blood group specificities using a two-stage technique. The optimal pH for treatment of red cells by activated papain or bromelain was between 5.4 and 5.8. Above this pH range, a fall in serological sensitivity was apparent which was much more pronounced with papain than with bromelain. The optimal pH for enzyme treatment of red cells can be achieved in two-stage techniques, but not in one-stage techniques due to the buffering effect of serum proteins.

Sensitive two-stage papain technique without cell washing

A two-stage papain technique is described in which cell washing after papain treatment is replaced by the addition of a specific papain inhibitor. This technique permits optimal enzyme treatment of red cells while digestion of immunoglobulin following the addition of serum is avoided. The technique therefore combines the design and consequent sensitivity advantage of two-stage tests with the convenience of one-stage tests, rendering it suitable for use in compatibility testing.

Transformation of T-lymphoid cells by Abelson murine leukemia virus

Abelson leukemia virus (A-MuLV) is an oncogenic murine retrovirus whose genome contains sequences homologous to those of a normal cellular gene, c-abl. It has been demonstrated to cause rapid transformation of several cell types, including pre-B lymphocytes, macrophages, and fibroblasts. More recently, A-MuLV has been reported to induce thymic tumors in a mouse strain (C57BL/Ka) previously thought to be resistant to disease induction. We showed that the masses occurring after intrathymic injection of the virus were composed of lymphocytes of a previously described immature T-cell phenotype. This phenotype has been defined here by flow cytometry of 10 primary tumor samples stained with antibodies to several thymocyte differentiation antigens. Hybridization of DNAs from these tumors with v-abl, immunoglobulin mu, and T-cell antigen receptor beta-chain probes confirmed the T-lymphoid, polyclonal nature of the primary tumor cells. The primary tumors were malignant, as clearly shown by reinjection into Thy-congenic host animals. Further, four Thy- in vitro cell lines derived from three tumors differed from the majority of primary tumor cells and were similar to previously described A-MuLV-transformed pre-B cells. The consistent T-lymphoid phenotype exhibited by primary A-MuLV thymomas may represent one stage of normal thymocyte differentiation.

Stimulation of phosphatidylcholine synthesis by fatty acids in fetal rabbit type II pneumocytes

After 24 h exposure to 0.1 mM oleate or 0.1 mM palmitate there was a 2- and 1.7-fold increase, respectively, in the incorporation of choline into the lipids of type II pneumocytes. Palmitate increased the labeling of disaturated phosphatidylcholine (PC) from 23.0% of total labeled PC in control cultures to 56.6% and oleate decreased labeling of disaturated PC to 9.4%. The percentage of total cellular radioactivity found in the lipid fraction was also markedly higher in the fatty acid-treated cells (83.3% for oleate and 78.7% for palmitate) than in control cultures (64.0%). Radioactivity in water-soluble choline metabolites was correspondingly lower, with phosphocholine representing more than 95% of the label in both control and experimental cultures. After a 3 h pulse-chase period, oleate and palmitate significantly increased the percentage of total cellular radioactivity in PC and decreased the percentage in phosphocholine. Similar results were obtained by adding melittin (1-2 micrograms/ml) or phospholipase C (0.05 U/ml) to the culture medium. The stimulation of PC synthesis by fatty acids was demonstrated as early as 1 h after exposure to oleate or palmitate and at all concentrations from 0.025 to 0.25 mM. Cytidylyltransferase activity in total cell homogenates was also enhanced by long-term exposure to fatty acids and short-term addition of fatty acids or phospholipase C and melittin to the culture medium. A similar increase in cytidylyltransferase activity was found in the 100 000 X g particulate fraction of type II cells exposed to fatty acids, whereas no differences were found between the cytosolic fractions of control and treated cells. These results support the concept that an increase in intracellular level of fatty acids either from an exogenous source or following the activation of endogenous phospholipases regulates PC synthesis in fetal type II pneumocytes.

Regulation of phospholipid synthesis by intracellular phospholipases in fetal rabbit type II pneumocytes

Exposure of fetal type II pneumocytes to phospholipase A2 inhibitors led to significantly reduced choline uptake and decreased synthesis of total and disaturated phosphatidylcholines from both [methyl-14C]choline and [9,10(n)-3H]palmitate precursors. The percentage of the total synthesized phosphatidylcholine recovered as disaturated phosphatidylcholine was increased when compared to that in control cultures, suggesting that unsaturated phosphatidylcholine synthesis was reduced to a greater extent than that of the disaturated species. Synthesis of sphingomyelin and phosphatidylethanolamine from labeled palmitate was also reduced, whereas that of phosphatidylinositol and phosphatidylglycerol was significantly increased. Addition of phospholipase C resulted in increased synthesis of phosphatidylcholine from both labeled precursors; no significant changes were found in synthesis of most of the other 3H-labeled lipids. Added phospholipase A2 did not lead to any changes in either choline or palmitate incorporation. However, when melittin (a phospholipase A2 activator) was added to the cultures, greater incorporation of both palmitate and choline was observed, along with a significant increase in the percentage of total cellular radioactivity in 14C-labeled lipids, indicating also stimulation of phosphatidylcholine synthesis. A marked increase in CTP: phosphorylcholine cytidylyltransferase activity was found after treatment of the cultures with phospholipase C. Exposure to quinacrine also increased the activity of this enzyme. Addition of phospholipase C and melittin to prelabeled pneumocyte cultures accelerated degradation of cell phospholipids and the release of free fatty acids as the main degradation products. These findings suggest that intracellular phospholipases are regulators of synthesis of surfactant phospholipids in fetal type II pneumocytes, and that activation or inhibition of these phospholipases could represent a mechanism through which hormones and pharmacological agents modify surfactant and other phospholipid synthesis.

Diminished in vitro responsiveness of circulating erythroid progenitor cells to insulin as an indicator of insulin resistance

While insulin resistance is considered characteristic of extreme obesity, it may be more difficult to demonstrate in less severe forms of obesity. We studied five moderately obese individuals [mean body mass index (MBMI), 34.1 +/- 1.85 (+/- SE) kg/m2], one massively obese patient (BMI, 50.2 kg/m2), and seven age-matched normal subjects (MBMI, 22.4 +/- 0.93 kg/m2). While two of the obese patients had normal glucose tolerance, all had fasting hyperinsulinemia (P less than 0.02 vs. normal subjects) and exaggerated insulin responses after oral glucose challenge, as defined by area under the 3-h insulin response curve (P less than 0.01 vs. normal subjects). That this hyperinsulinemia represented in vivo insulin resistance was supported by the glucose and insulin responses in four individuals to an iv glucose bolus analyzed by the minimal modeling technique. Study of monocyte insulin receptors revealed no reduction in total insulin binding in the four obese patients tested. Since physiological concentrations of insulin stimulate the in vitro growth of normal human erythroid progenitor cells (EPC), we reasoned that this response might be blunted in cells from individuals with endogenous insulin resistance. The mean peak EPC proliferative response (26.7 +/- 9.11% above baseline) in the obese hyperinsulinemic group was significantly less than the corresponding mean value in the control group (92.6 +/- 5.24% above baseline, P less than 0.001). These results suggest that the minimal modeling technique is a sensitive method for the in vivo demonstration of insulin resistance in moderately obese individuals and that EPC responsiveness to physiological concentrations of insulin reflects in vivo insulin sensitivity and may be used as an in vitro indicator of insulin resistance.

Patterns of thymocyte differentiation markers on virus and radiation induced lymphomas of C57BL/Ka mice

To better understand the biology of tumorigenesis in virus and radiation lymphomas of C57Bl/Ka mice, we have examined the cell surface phenotypes of a large series of primary tumors induced by both agents. Data derived using flow cytometry and recently available monoclonal antibodies to thymocyte differentiation antigens supports three major conclusions. First, tumor cell populations are unimodal for staining with most antibodies and are probably of clonal origin. Second, many, but not all, tumor cells show surface phenotypes similar to those of previously defined subpopulations of normal thymocytes. Third, at the cell surface level, no major differences between virus- and radiation-induced lymphomas can be discerned. Our data thus further define the relationship between thymomas induced by these two agents.

Neuropsychological performance of sexual assaulters and pedophiles

Persons who had been arrested for sexual assault were administered the Luria-Nebraska Neuropsychological Battery and the results compared to a group of normal controls. The sexual assaulters performed significantly worse on 7 of the 14 scales of the battery. The data were then broken down into three groups: (1) those who had forcibly assaulted postpubescent victims, (2) those subjects who had sexually molested a prepubescent child, and (3) normal controls. A discriminant analysis correctly classified 68% of the subjects on the basis of their neuropsychological performance alone.

Nucleotide sequence of the large terminal repeat of two different strains of gibbon ape leukemia virus

Gibbon ape leukemia virus, SEATO strain (GaLV-SEATO), a virus that induces myeloid leukemia in gibbon apes, and GaLV, San Francisco strain (GaLV-SF), a virus associated etiologically with lymphocytic leukemia in gibbon apes, have been molecularly cloned. The complete nucleotide sequence of the large terminal repeats (LTRs) of both viruses are reported and compared to the previously published nucleotide sequence of the LTR of another member of the same virus group, the simian sarcoma virus (SSV). Substantial homology is evident among all three LTR sequences. The most striking feature of the GaLV-SEATO LTR is the presence of a 45-bp tandem direct repeat in the U3 region, an area likely to contain transcriptional enhancers. Both GaLV-SEATO and GaLV-SF contain a deletion in U3 when compared to SSV. Each of the three LTRs differ from the other two by short deletions in R-U5 and short additions in U3, as well as by numerous point mutations. The possibility that the structural changes observed in the LTR contribute to the differences in the pathogenic effects of these viruses is discussed.

Insulin receptors in fetal rabbit lung type II cells

Insulin binding was studied in type II pneumocytes isolated from fetal rabbit lungs (27 days of gestation) and grown in monolayers in tissue culture. The mean high affinity receptor site number was 11.8 +/- 1.4 X 10(3) (+/-SEM)/cell, with a Kd of 0.45 +/- 0.07 nM (n = 6). Low affinity sites averaged 432 +/- 10.7 X 10(3)/cell, with a Kd of 45.6 +/- 11.8 nM. Incubation of the cells with 5 X 10(-10) M (Bu)2cAMP (DBcAMP) and 10(-3) M methylisobutylxanthine (MIX) for 18 h led to significant increases in the number of high affinity receptor sites and Kd (P = 0.025 and 0.05, respectively). Incubation of the cells with insulin (1 microgram/ml) for 18 h led to a significant diminution in the mean number of high affinity sites to 3.23 +/- 0.68 X 10(3)/cell (P = 0.0025). There was no significant change in the Kd of the high affinity sites. There was also no significant change in the number or affinity of the low affinity sites. When the cells were incubated with insulin in the presence of DBcAMP (5 X 10(-4) M) and MIX (10(-3) M), there was a significant increase in high affinity binding sites to a mean of 8.87 +/- 2.18 X 10(3)/cell (n = 4) compared to the value after incubation in the presence of insulin alone. There was no significant increase in the Kd of the high affinity sites. The following conclusions were drawn from these experiments. 1) Fetal type II pneumocytes possess receptors with high affinity for insulin. 2) The up-regulation of insulin receptor binding induced by high ambient concentrations of insulin in vivo in rabbit fetal lungs and circulating human monocytes does not occur in vitro when isolated pneumocytes are grown in tissue culture. 3) Insulin binding to type II pneumocytes is enhanced by DBcAMP and MIX. 4) Insulin down-regulation of receptor binding is significantly counteracted by DBcAMP and MIX.

Effects of cyclic AMP analogues and phosphodiesterase inhibitors on phospholipid biosynthesis in fetal type II pneumocytes

Purified type II pneumocytes grown in monolayer cultures after isolation from fetal rabbit lung organotypic cultures were employed to investigate effects of cAMP analogues and phosphodiesterase inhibitors on [methyl-14C]choline and [9-10(n)3H]palmitate incorporation into cell lipids. After 24 h exposure to 0.5 mM N6,O2-dibutyryl-cAMP or 8-bromo-cAMP, a significant increase was found in the rate of incorporation of choline into phospholipids. Addition of 1 mM 1-methyl-3-isobutylxanthine or aminophylline also increased incorporation of choline into phospholipids but did not significantly change the incorporation of choline into sphingomyelin. These effects were not due to increased uptake of choline or changes in the pool size of the precursor. Cyclic AMP analogues also stimulated the rate of incorporation of palmitate into most lipid fractions but did not alter the relative percentages of incorporation of either precursor into any of the phospholipids. Phosphodiesterase inhibitors did not significantly change the rate of incorporation of palmitate into neutral lipids and most phospholipids, except for a decrease into sphingomyelin, phosphatidylinositol and phosphatidylethanolamine. However, they increased the percentage of incorporation of palmitate into phosphatidylcholine and decreased the percentage of incorporation into most other phospholipids. These data clearly indicate that cAMP can stimulate the synthesis of phospholipids within the type II pneumocytes. This effect is probably a general stimulation effect for the cAMP analogues but methylxanthines may selectively increase the synthesis of surfactant lipids such as phosphatidylcholine while decreasing that of other membrane-associated phospholipids.

Monoclonal antibodies detect a spectrin-like protein in normal and dystrophic human skeletal muscle

Spectrin is the major protein of the erythrocyte membrane skeleton, which is bound to the cytoplasmic surface of the membrane's lipid bilayer and is responsible for cell shape and membrane elasticity. Inability to identify spectrin in other cell types led to the assumption that this protein was unique to erythrocytes. However, spectrin-like proteins have been demonstrated recently in a variety of cell types, including skeletal and cardiac muscle, in several species. We used monoclonal antibodies against human erythrocyte spectrin subunits in an immunocytochemical study to detect related proteins in normal and diseased human skeletal muscle. Six of seven monoclonal antibodies against beta-spectrin determinants were bound at the cytoplasmic surface of muscle fiber plasma membranes, whereas none of six monoclonal antibodies against alpha-spectrin determinants was bound. Muscle fibers of patients with neuromuscular diseases showed similar distribution and specificity of antibody binding to those of normal subjects, but the intensity of binding was increased. In contrast, probable regenerating fibers in muscle of patients with muscular dystrophies showed reduced binding of antibodies, but reduced binding was not seen in fetal muscle fibers nor in those of a patient with a myotubular myopathy. We conclude that human skeletal muscle fibers possess a spectrin-related protein associated with their plasma membrane that shows extensive beta-chain similarities to erythrocyte spectrin but differs significantly with respect to the alpha-subunit. Its function may be associated with the maintenance of membrane and myofibril integrity during contraction, and the increased antibody binding in diseased muscle may reflect a structural rearrangement of spectrin or a compensatory increase in spectrin abundance in response to increased stress on these systems.

Self-monitoring of blood glucose levels and intensified insulin therapy. Acceptability and efficacy in childhood diabetes

Prospective studies have shown that children and adolescents with diabetes have a high prevalence of serious complications and a sharp reduction in life expectancy. Recently, self-monitoring of blood glucose levels has become available and, for the first time, provides a method for determining the concentration of blood glucose with considerable accuracy. We have introduced this method of control assessment to our pediatric diabetic patient population in conjunction with a program of intensified insulin administration (two or more injections per day). This is a report of the ready acceptance of these methods by children and adolescents and their parents (53/63, or 84%). The effectiveness of this program is evidenced by a progressive and significant reduction in the percentage of glycosylated hemoglobin during a period of 18 months in a majority of the subjects. These observations suggest that improved glycemic control can be achieved in young diabetics by using multiple insulin injections and self-monitoring of blood glucose levels. Whether such control can lead to a better long-term outlook for diabetics remains to be seen.

Comparison of late degenerative changes in porcine bioprostheses in the mitral and aortic valve position in the same patient

Porcine bioprostheses implanted in both the mitral and aortic valve positions simultaneously in 5 patients aged 20 to 61 years (mean 45) were reexamined 18 to 107 months (mean 51) later. In 4 patients, the degenerative changes were distinctly more severe in the bioprostheses in the mitral than in the aortic valve position.

Ventricular enlargement in major depression

Major depression accompanied by psychosis may be a separate nosological entity from nonpsychotic depression. Investigators have noted behavioral and biochemical differences in psychotic and nonpsychotic patients, as well as differences in response to treatment. A previous study using computed tomography (CT) found enlargement of the lateral cerebral ventricles in patients with manic-depressive illness with psychotic symptoms. The present study examined CT scans of patients with major affective illness that was accompanied by hallucinations, delusions, or both. The ventricles of the depressed group were significantly larger than those of a group of normal controls.