Interaction of neurotensin, cholecystokinin, and secretin in the stimulation of the exocrine pancreas in the dog

The effects of exogenous neurotensin, secretin, and cholecystokinin-33 alone and in combination on pancreatic secretion were investigated in dogs prepared with pancreatic fistulae. Neurotensin infused intravenously caused a dose-dependent stimulation of exocrine pancreatic secretion. Increasing doses of neurotensin combined with a constant small dose of secretin potentiated pancreatic output of protein and had a tendency to reduce secretion of the bicarbonate. Increasing doses of neurotensin combined with a constant small dose of cholecystokinin-33 potentiated pancreatic output of bicarbonate and lead to a reduction (insignificant) of pancreatic protein secretion. These observations suggest an interaction of neurotensin with pancreatic receptors for secretin and cholecystokinin.

Elimination of endogenous xenotropic retroviruses from peritoneal macrophages in virus-induced T cell lymphoma

Peritoneal macrophages did not support the replication of 136 . 7 and 4SP, T cell lymphoma-inducing viruses, either in vivo or in vitro. Interestingly, endogenous xenotropic viruses, which were detected in more than 50% of the tested samples of peritoneal macrophages of normal C57BL/6 mice, were eliminated from peritoneal macrophages removed from 136 . 7- or 4SP-inoculated, T cell lymphoma-bearing mice. This elimination occurred about 2 weeks after virus inoculation. X-irradiation (400 rads) seemed to accelerate the elimination of xenotropic viruses from the peritoneal macrophages of mice inoculated with the radiation-dependent variant, the 4SP virus. The significance of this elimination of viruses from macrophages following inoculation with T cell lymphoma-inducing viruses is discussed.

Catecholamine-stimulated ion transport in duck red cells. Gradient effects in electrically neutral [Na + K + 2Cl] Co-transport

The transient increase in cation permeability observed in duck red cells incubated with norepinephrine has been shown to be a linked, bidirectional, co-transport of sodium plus potassium. This pathway, sensitive to loop diuretics such as furosemide, was found to have a [Na + K] stoichiometry of 1:1 under all conditions tested. Net sodium efflux was inhibited by increasing external potassium, and net potassium efflux was inhibited by increasing external sodium. Thus, the movement of either cation is coupled to, and can be driven by, the gradient of its co-ion. There is no evidence of trans stimulation of co-transport by either cation. The system also has a specific anion requirement satisfied only by chloride or bromide. Shifting the membrane potential by varying either external chloride (at constant internal chloride) or external potassium (at constant internal potassium in the presence of valinomycin and DIDs [4,4'-diisothiocyano-2,2'-disulfonic acid stilbene]), has no effect on nor-epinephrine-stimulated net sodium transport. Thus, this co-transport system is unaffected by membrane potential and is therefore electrically neutral. Finally, under the latter conditions-when Em was held constant near EK and chloride was not at equilibrium-net sodium extrusion against a substantial electrochemical gradient could be produced by lowering external chloride at high internal concentrations, thereby demonstrating that the anion gradient can also drive co-transport. We conclude, therefore, that chloride participates directly in the co-transport of [Na + K + 2Cl].

Immunopathology of B-cell lymphomas induced in C57BL/6 mice by dualtropic murine leukemia virus (MuLV)

Combined clinicopathologic and immunomorphologic evidence is presented that would indicate that a murine leukemia virus (MuLV) with the dualtropic host range is capable of producing a clinically malignant lesion composed of immunoblasts and associated plasma cells in C57BL/6 mice. This process, morphologically diagnosed as an immunoblastic lymphoma of B cells using standard histopathologic criteria, was found to be distinctly polyclonal with regard to immunoglobulin (Ig) isotype when analyzed for both surface and cytoplasmic Ig. Further studies demonstrated that this clinicopathologically malignant, dualtropic MuLV-induced, polyclonal immunoblastic lymphoma of B cells in C57BL/6 mice was normal diploid and unable to be successfully transplanted to nonimmunosuppressed syngeneic recipients. Although all serum heavy and light chain components were found to be progressively elevated as the tumor load increased, the polyclonal increase in serum immunoglobulins was most pronounced for mu heavy and kappa light chains (ie, mu greater than gamma 2A greater than alpha greater than gamma 2B greater than gamma 1; kappa greater than lamba). The dissociation of clinicopathologic and biologic criteria for malignancy in the presently described dualtropic (RadLV) MuLV-induced B-cell lesion is sharply contrasted with the thymotropic (RadLV), MuLV-induced T-cell lymphoblastic lymphoma in C57BL/6 mice. This process is also a clinicopathologically malignant lesion but, when one uses biologic criteria, is found to be distinctly monoclonal, aneuploid, and easily transplanted to nonimmunosuppressed syngeneic recipients. The close clinicopathologic and biologic similarities of the dualtropic MuLV-induced animal model to corresponding human B-cell lymphoproliferative diseases are stressed.

Involvement of peritoneal macrophages and spleen stromal cells in X-irradiation-induced reticulum cell neoplasms in C57BL/6 mice

Some correlation was observed between the occurrence of FA-positive PE-MO and spleen stromal cells (removed from X-irradiated RCN-bearing old-adult B6 mice) and the generation of RCN. No significant correlation was found between the viral content of lymphoid organs from the same mice and the occurrence of RCN. The main viral particle detected in lymphoid organs from radiation-induced RCN-bearing mice was the xenotropic virus. Ecotropic viruses were detected in a few spleens and Payer patches from such mice. These ecotropic viruses showed very poor lymphomagenic activity and required 400R X-ray as a cofactor. No dualtropic viruses were detected. However, inoculation of ecotropic (SFA2) helper virus to X-irradiated old-adult B6 mice, resulted in an efficient rescue of lymphomagenic viruses, enriched with phenotypically mixed, dualtropic viruses. Some of these DT viral preparations were cloned and seemed to consist mainly of xenotropic sequences. Thus, inoculation of helper viruses influenced the generation and selection of DT viruses. Such viral preparations, enriched with DT viruses, had a better lymphomagenic activity compared to endogenous ecotropic viruses, isolated from radiation-induced RCN-bearing mice. Indirect evidence suggested the involvement of a defective (xenotropic and possibly adjacent cellular genes) particle in lymphoma induction. To conclude, a possible mechanism for the development of radiation-induced RCN is suggested, emphasizing the role of MO in such a process.

Effect of neurotensin on regional intestinal blood flow in the dog

The effects of various doses of synthetic neurotensin on regional blood flow in different tissue layers of the stomach, small bowel, colon, pancreas, brain, kidneys, adrenal gland, and heart of six dogs was studied using an isotope microsphere technique. Infusion of high doses (20, 40 pmol/kg . min(-1)) of exogenous synthetic neurotensin caused an increase of blood flow in the "muscularis" of duodenum, jejunum, ileum, and colon. Neurotensin infused in a dose (2.5 pmol/kg . min(-1)) raising neurotensin plasma levels to concentrations comparable to those observed after a meal caused an increase of blood flow in the muscular layer in ileum. Our results suggest that one of the physiologic actions of neurotensin may be the regulation of blood flow in the muscular layer of the ileum.

Abrogation of radiation leukemia virus-induced lymphomagenesis by antisera to thymotropic but not to ecotropic or dual-tropic viruses

Leukemia induction by culture-grown thymotropic radiation leukemia virus or by tumor-derived virus present in cell-free tumor extracts was abrogated by incubation of either virus with anti-thymotropoc virus serum, but not by antiserum raised against ecotropic or dual-tropic (mink cell focus-inducing type) viruses that were isolated from radiation leukemia virus-induced thymic leukemias. Thus, virus similar or identical to the cultured thymotropic leukemogenic species may also be the major biologically active principle in tumor-derived extracts, even though the latter also contain viruses of the dual-tropic, mink cell focus-inducing type class.

Genomic masking and rescue of dual-tropic murine leukemia viruses: role of pseudotype virions in viral lymphomagenesis

The kinetics of genomic masking of nondefective dual-tropic murine leukemia viruses (MuLV) by ecotropic MuLV in mixedly infected mouse cells was studied. The ratio of virus infection (ecotropic to dual-tropic) determined the kinetics of genomic masking. Some dual-tropic virus isolates could be masked routinely (i.e., converted to virions containing a dual-tropic genome and possessing the ecotropic host range) at all ratios of initial infection of mixedly infected mouse cells. The masked genomes could be rescued as infectious viruses of dual-tropic genotype and host range by an infectious center assay of the infected mouse cells on mink lung cells. Infectious center rescue of masked dual-tropic MuLV took place readily, even from cells that had been kept in continuous culture for many months after the onset of genomic masking. Some dual-tropic virus clones did not undergo genomic masking at any infection ratio with ecotropic virus. Nevertheless, such mixedly infected cultures also gave rise to phenotypically mixed virions, which contained a dual-tropic genome and had an ecotropic host range. (The phenotypically mixed virions found among the progeny of mixedly infected mouse cells were not pseudotypes, as both types of viruses were genetically nondefective, nor was the process leading to their generation a bona fide phenotypic mixing [Fischinger et al., Science 201:457-459, 1978]. Nevertheless, in this paper we use the terms pseudotype and phenotypic mixing because of the lack of a better description.) The lymphomagenic potential of dual-tropic lymphomagenic MuLV was compared with that of phenotypically mixed virions possessing an ecotropic host range and with that of a simple mixture of dual-tropic and ecotropic viruses. The phenotypically mixed pseudotype virions were more potent lymphoma inducers than were those of dual-tropic, cloned genotype. Inoculation of a simple mixture of the viruses did not increase dual-tropic virus tumorigenicity. The reason for this was probably the highly efficient inactivation of dual-tropic virus by oncovirus-inactivating factor, which is present in normal mouse serum and did not inactivate the phenotypically mixed virions. Simple mixtures of dual-tropic lymphomagenic and ecotropic virus preparations behaved like the cloned, dual-tropic virus in vivo and were equally sensitive to oncovirus-inactivating factor in vitro. Thus, phenotypic mixing of dual-tropic and ecotropic MuLV with or without concomitant genomic masking may be a highly significant phenomenon in naturally occurring lymphomagenesis. It may also be important to use phenotypically mixed viruses in the procedures used for in vivo testing of lymphomagenic dual-tropic MuLV isolates.

Cell-surface antigens associated with dualtropic and thymotropic murine leukemia viruses inducing thymic and nonthymic lymphomas

Unique type-specific antigens were detected on cells infected with dualtropic and thymotropic viruses isolated and x-ray-induced T cell- and B cell-malignant lymphomas of C57BL/6 mice. These antigens were defined by membrane fluorescence with antisera made in rabbits against rabbit cells chronically infected with cloned virus. The antisera were qualitatively absorbed with a group of cells chronically infected with related dualtropic, ecotropic, and xenotropic viruses. The absorbed antisera detected type-specific, virus-related cell-surface antigens that were unique for different dualtropic virus isolates. The unabsorbed sera also reacted with antigens found specifically on ecotropic and xenotropic virus-infected cells. These findings support the contention that T cell lymphoma (TCL)-inducing and B cell lymphoma (BCL)-inducing viruses isolated from x-irradiated C57BL/6 mice are env gene recombinants in which ecotropic gene sequences have been substituted by xenotropic sequences. We found that unique antigenicities are associated with each TCL-inducing and BCL-inducing dualtropic virus, and that the thymotropic TCL-inducing virus isolates (e.g., 136.5 adn 136.7 viruses) represent a separate serologic group, different from the dualtropic TCL-inducing viruses. By using a series of absorbed antisera in microimmunofluorescence tests we could perform serologic virus mapping of dualtropic clones isolated by us or by others and relate them serologically to previously isolated clones. These virus mapping experiments indicated that many serologically different recombinant viruses can be isolated from C57BL/6 mice. It is suggested that many distinct recombinant viruses may exist in lymphomagenic C57BL/6 mice, some of which are associated with specific lymphoma induction.

Reticulum cell neoplasms induced in C57BL/6 mice by cultured virus grown in stromal hematopoietic cell lines

Thirty-one adherent cell lines have been established from the spleens, lymph nodes, and bone marrow of C57BL/6 mice carrying radiation leukemia virus (Duplan isolate)-induced reticulum cell neoplasms (RCN). The cell lines had a stable epithelial or fibroblastoid morphology, Supernatant virus from these lines induced splenic and lymph node RCN in 100% of inoculated C57BL/6 mice within 30 days. The disease was generalized and involved many organs. The monolayer cells themselves were not tumor cells and induced RCN through infection of the host with RCN virus. Simultaneous inoculation of in vitro-grown RCN-inducing virus any thymic lymphosarcoma virus induced each disease independently with unaltered incidence, latency period, and organ involvement; no mutual enhancement or inhibition was found, thus two separate mechanisms of action were indicated. Reextraction of the viruses from spleen, lymph nodes, and thymus gland indicated the specific organotropism of each agent. All the adherent cell lines that were derived from hematopoietic tissues produced ample, potent RCN-inducing virus. This high success rate suggests that in the hematopoietic organs the stromal, fibroblastoid cells are a natural habitat for the RCN-inducing virus. The RCN-inducing virus species may well be synthesized in these hematopoietic stromal cells. RCN-inducing virus from culture supernatants contained high-titer infectious ecotropic and xenotropic virus that was titrated. The cultures are being used to clone the RCN-inducing virus and to establish the virologic and molecular properties that endow it with specific RCN-inducing capacity.

Lithium transport pathways in human red blood cells

In human red cells, Li is extruded against its own concentration gradient if the external medium contains Na as a dominant cation. This uphill net Li extrusion occurs in the presence of external Na but not K, Rb, Cs, choline, Mg, or Ca, is ouabain-insensitive, inhibited by phloretin, and does not require the presence of cellular ATP. Li influx into human red cells has a ouabain-sensitive and a ouabain-insensitive but phloretin-sensitive component. Ouabain-sensitive Li influx is competitively inhibited by external K and Na and probably involves the site on which the Na-K pump normally transports K into red cells. Ouabain does not inhibit Li efflux from red cells containing Li concentrations below 10 mM in the presence of high internal Na or K, whereas a ouabain-sensitive Li efflux can be measured in cells loaded to contain 140 mM Li in the presence of little or no internal Na or K. Ouabain-insensitive Li efflux is stimulated by external Na and not by K, Rb, Cs, choline, Mg, or Ca ions. Na-dependent Li efflux does not require the presence of cellular ATP and is inhibited by phloretin, furosemide, quinine, and quinidine. Experiments carried out in cells loaded in the presence of nystatin to contain either only K or only Na show that the ouabain-insensitive, phloretin-inhibited Li movements into or out of human red cells are stimulated by Na on the trans side and inhibited by Na on the cis side of the red cell membrane. The characteristics of the Na-dependent unidirectional Li fluxes and uphill Li extrusion are similar, suggesting that they are mediated by the same Na-Li countertransport system.

Radioimmunoassayable plasma vasopressin associated with surgery

Plasma vasopressin concentration was measured by radioimmunoassay before, during, and after anesthesia and surgery in ten subjects. During the short period between the onset of anesthesia and the start of operation, small elevations of vasopressin level were noted. Surgery itself was associated with significant elevations of up to 82 pg/ml. Highest levels of vasopressin were noted with major intra-abdominal surgery and lowest levels with limb surgery. The immediate postoperative period was marked by plasma vasopressin levels that were often higher than during surgery itself. Levels gradually fell to their preoperative state after three to four days. The elevated levels of vasopressin can be associated with oliguria and excessive water retention. Among the possible mechanisms for the stimulus to vasopressin secretion are pain, stress, positive pressure respiration and anoxia. This study confirms by radioimmunoassay the changes in plasma vasopressin level with surgery that have been previously described by bioassay.

Leukemogenic activity of thymotropic, ecotropic, and xenotropic radiation leukemia virus isolates

Thymotropic, ecotropic, and xenotropic oncoviruses were isolated from the C57BL/6 mouse radiation leukemia system and were propagated in culture. The purified viruses were inoculated singly and in various combinations into groups of mice, and leukemia incidence was determined. Only the thymotropic virus was leukemogenic in vivo.

Genetic analysis of in vitro leukemogenesis induced by thymus epithelial reticulum cells transmitting murine leukemia viruses

Lymphatic leukemia developed in C57BL/6 mice following inoculation of normal thymocytes that and been co-cultured on leukemic thymus epithelial reticulum monolayer cells. Using thymocytes genetically marked in Ly membrane antigens, we showed that the thymomas which developed were produced by the co-cultured thymocytes rather than by leukemic cells derived from the monolayer. Thus, leukemogenic conversion of normal thymocytes took place in vitro. Inoculation of cultured leukemic thymus epithelial reticulum monolayer cells (LTER) gave rise mainly to reticulum cell sarcomas and myeloid leukemias, rather than to lymphatic leukemias (which developed following inoculation of thymocytes that had been cultured on the LTER monolayers). Thus LTER cells may themselves be tumor cells capable of producing RCNA (reticulum cell neoplasm type A) or myeloid tumors in addition to their ability to convert normal thymocytes into leukemic cells.

Abnormal lithium and sodium transport in erythrocytes of a manic patient and some members of his family

This paper compares the transport of Li(+) and Na(+) in erythrocytes from a patient with mania and from members of his family to that in erythrocytes from normal humans. In normal human erythrocytes, Li(+) is transported by at least three operationally distinct pathways: one inhibited by ouabain (ouabain-sensitive), one by phloretin (phloretin-sensitive), and one not inhibited by either compound (insensitive). Li(+) can be driven up its electrochemical potential gradient by an oppositely directed electrochemical potential gradient for Na(+)-i.e., Li(+)/Na(+) counterflow can occur-through the phloretin-sensitive pathway but not through the other two pathways. Because ouabain-sensitive Li(+) transport is negligible under physiological conditions, Li(+) distribution between erythrocytes and plasma in vivo depends mainly on the balance between Li(+)/Na(+) counterflow and the insensitive pathway(s) of Li(+) transport. The steady-state ratio of Li(+) concentration in the erythrocytes to that in the plasma of the patient was between 2 and 3 times higher than the comparable ratio in normal persons. The phloretin-sensitive Li(+)/Na(+) counterflow system was almost absent in the erythrocytes of the patient. Furthermore, unlike those from normal individuals, the patient's erythrocytes showed no external Li(+)-stimulated, phloretin-sensitive, ouabain-insensitive Na(+) efflux. The magnitudes of the ouabain-sensitive and insensitive pathways for Li(+) transport in the patient's erythrocytes were within normal limits. The decreased Li(+)/Na(+) counterflow in the patient's erythrocytes was probably not due to the presence of an inhibitor in the plasma of the patient but rather to an intrinsic defect in the erythrocytes. Because the father and several siblings of the patient showed a similar abnormality in erythrocyte Li(+)/Na(+) transport, it is probable that this defect is inherited.

Leukemogenesis in vitro induced by thymus epithelial reticulum cells transmitting murine leukemia viruses

The role of the thymus in induction of leukemia was studied in vitro. Curltivation of normal thymus cells on thymus epithelial reticulum cell monolayers that had been grown from radiation leukemia virus-induced leukemic thymuses rendered the thymocytes leukemic. C57BL/6 thymocytes were cultivated for 3 days on leukemic thymus reticulum monolayers, and 106 thymocytes were injected i.p. into young adult C57BL/6 mice. After 3 to 4 weeks all mice died of disseminated lymphatic leukemia. Mice given thymocytes that had been cultivated on thymus epithelial reticulum monolayers from normal mice did not develop lymphomas. The leukemic thymus epithelial reticulum cells were shown to produce thymotropic as well as ecotropic and xenotropic radiation leukemia virus. (Thymotropic virus has affinity for thymus lymphocytes but noes not infect fibroblasts.) The cells were brightly positive for murine leukemia virus group-specific antigen in immunofluorescence tests. Leukemic thymus epithelial reticulum cells produced ample infectious exotropic virus in the culture supernatant, although the cells were negative in the XC syncytia test. Upon infection of mouse fibroblasts with ecotropic virus produced by the leukemic reticulum cells, XC syncytia were readily obtained. Thymocytes that were cultivated on leukemic thymus reticulum cells became positive for murine leukemia virus group-specific antigen and produced syncytia in the XC test. Thus, in vitro lymphomagenesis of the thymocytes that were cultured on leukemic thymus reticulum cells was associated with their infection with thymotropic and ecotropic radiation leukemia virus.

Medical student education in psychiatry

The authors interpret data obtained from 99 medical schools which submitted grant applications for support of either undergraduate psychiatric education programs or human behavior programs. They tentatively conclude that high-quality programs for teaching medical students psychiatry are characterized by a well-rounded faculty, a psychodynamic orientation, a greater commitment to medical student education than to resident training, varied teaching methods, enthusiastic student response, and systematic evaluation that produces change in subsequent years.

Transient virus expression during murine leukemia induction by X-irradiation

Most X-irradiation-induced thymomas in C57BL/6 mice are virus-free when assayed by immunofluorescence for the gs antigen (gsa) of murine leukemia virus (MuLV). Virus was induced transiently in bone marrow cells and later appeared in thymus cells. Six to 7 weeks post irradiation, thymocytes and bone marrow cells were MuLV gsa-negative and remained negative for the lifetime of most animals, whether or not they contracted overt leukemia. During the period when MuLV gsa-positive bone marrow cells were found, XC-positive syncytia-producing bone marrow cells were also found. Virus information was expressed, therefore, for a limited duration, long before any signs of leukemia in the animals were evident. MuLV gsa-positive thymocytes taken from mice 4 weeks after X-irradiation were cocultivated with a series of indicator cells. B-tropic virus, in addition to a xenotropic virus, was isolated from these cells. Ecotropic virus was not found in normal mouse thymocytes, in irradiated thymocytes a few days after termination of the X-irradiation sequence, or in most primary thymomas. All thymocytes produced only xenotropic virus in the cocultivation assays. Expression of the ecotropic virus was, therefore, transient, as assayed by immunofluorescence, XC syncytia formation, and virus isolation from MuLV gsa-positive thymus cells.

[Comparative studies on the teaching of oral pathology]

This is a self-assessment of teaching effectiveness for teacher, students and teaching-material as well. A curriculum of oral patholology was created and prepared as syllabus, lectures and audiovisual aids. In order to estimate and compare the eductional achievements of different systems, a series of written multiple choice questions were prepared. Only items with an index of discrimination of more than 0,25 were used. The average index was 0,5. The results of a short-term experimetn (1 hour) shows that a teaching sequence in the conventional lecture style was most effective in transmitting knowledge (72% of maximum), audiovisual aids rating second (63%), followed by individual homework study using printed material (48%). The differences were statistically significant in most experiments. In the second type of experiment (long-term-experiment) we registered the time the students spent with lectures over a period of six months. When permitted to chose between the different systems the students preferred the audiovisual method to the lectures. Individual testing of these students shows a positive correlation between knowledge acquired and time spent with the audiovisual machines.

Pulsed nuclear magnetic resonance study of 17O from H217O in rat lymphocytes

Lymphocytes obtained from thymus glands of normal rats and culture lines of malignant rat thymocytes were enriched with H217O. The longitudinal and transverse relaxations of the 17O were determined separately in samples of packed cells and supernatant solutions. The longitudinal relaxation of intracellular 17O of fresh viable lymphocytes was nonexponential, becoming simply exponential with eventual necrosis. The rate of spin-lattice relaxation (1/T1) was fitted by a sum of two exponentials. The average mole fraction of the molecules subject to the slower relaxation rate (1/T1s) was two-thirds of the total water. Lowering the Larmor frequency (omega) from 7.72 to 4.36 MHZ increased the faster component (1/T1f) by 12% without altering (1/T1s). The value of the single exponential decay of the nonviable cells was not appreciably different from the initial rate of relaxation of the fresh cells. Similar results were obtained in studies of the transverse relaxation rates. The simplest interpretation is that two-thirds of the cell water is located within the nucelus and is characterized by a slower rate of relaxation than the one-third of the cell water in the cytoplasm because of the different macromolecular compositions of the two-subcellular compartments. The malignant lymphocytes were characterized by prolonged values for the slow and fast components of both the longitudinal and transverse relaxations of 17O.

Enzymatic modification of aminoglycoside antibiotics: a new 6'-N-acetylating enzyme from a Pseudomonas aeruginosa isolate

We describe an aminoglycoside 6'-N-acetyltransferase, isolated from Pseudomonas aeruginosa, that exhibits a novel substrate profile characterized by markedly reduced activity towards butirosin and amikacin.

Enzymatic modification of aminoglycoside antibiotics: a new 3-N-acetylating enzyme from a Pseudomonas aeruginosa isolate

A new 3-N-aminoglycoside acetyltransferase is described, which possesses a wider substrate range than any such enzyme so far discovered in clinical isolates of antibiotic-resistant bacteria.