Botulism in metronidazole- treated conventional adult mice challenged orogastrically with spores of Clostridium botulinum type A or B

Conventional adult mice were pretreated with metronidazole to make their intestinal tracts receptive to colonization by Clostridium botulinum. These mice, in groups of 10, were fed 0 (controls), 10(2), 10(3), 10(4), or 10(5) C. botulinum type B spores and were placed for observation in filter-lid cages whose screen floors minimized the amounts of feces available for coprophagy. The opportunity to eat feces was made equal for all mouse groups by placing one mouse of every group in each of 10 cages. Mice given a spore inoculum began to develop botulism after incubation periods of slightly less than 2.75 days. Morbidity rates, which reached maxima within 5 days of challenge, were related to inocula levels. Mortality rates were also dose related. Mice given 10(5) spores and then type B antitoxin intraperitoneally, a treatment not affecting intraintestinal toxin production, remained healthy. Morbidity among control mice was seldom more than 10% and could be ascribed to toxin ingested with feces. A C. botulinum type A spore suspension gave similar results, although morbidity and mortality rates were generally lower than after challenge with a comparable number of type B spores. Mice challenged with 10(2) or 10(5) spores had similar toxin levels in their large intestines 48 h later. Morbidity rates correlated better with toxin levels in the small intestines.

Atrial volume in a normal adult population by two-dimensional echocardiography

Left atrial (LA) and right atrial (RA) volumes were calculated from two-dimensional echocardiography (2D echo) in 54 normal volunteers, of whom 23 were nonathletic men and 25 nonathletic women; 6 additional men had a history of athletic training. Ages ranged from 20 to 66 years (average nonathletic group, 38 years; athletic men, 28 years). The LA volume was measured by single-plane area-length algorithm from apical 2-chamber (2CH) and 4-chamber (4CH) views and from their combination by means of Simpson's rule. The RA volume was analyzed only in the 4CH view. Mean LA volume was larger for men than women; for nonathletic men, 46 +/- 14 ml for 2CH view and 38 +/- 10 ml for both the 4CH view and for Simpson's rule combination of the apical views. For women it was 36 +/- 11 ml for the 2CH view, 34 +/- 12 ml for the 4CH view, and 32 +/- 10 ml by Simpson's rule. Right atrial volume was 39 +/- 12 ml in nonathletic men and 27 +/- 7 ml in women. In the six athletic men, LA volume and volume index, but not RA volume and volume index, were significantly larger than in nonathletes. These findings in this small sample suggest that caution should be exercised in interpreting atrial enlargement in athletes. There were no significant correlations between atrial volumes and age, although individuals over 65 years with normal hearts were not represented. In evaluating LA volume in a given patient, it is advisable to use specific values for each apical view and algorithm and to correct for either sex or body surface area (BSA) but not for both. In the RA it is necessary to correct for both sex and BSA.

Control of glycogen synthase phosphorylation in isolated rat hepatocytes by epinephrine, vasopressin and glucagon

Isolated rat hepatocytes were incubated in a medium containing 0.1 mM [32P]phosphate (0.1 mCi/ml) before exposure to epinephrine, glucagon or vasopressin. 32P-labeled glycogen synthase was purified from extracts of control or hormone-treated cells by the use of specific antibodies raised to rabbit skeletal muscle glycogen synthase. Analysis of the immunoprecipitates by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicated that a single 32P-labeled polypeptide, apparent Mr 88000, was removed specifically by the antibodies and corresponded to glycogen synthase. Similar electrophoretic analysis of CNBr fragments prepared from the immunoprecipitate revealed that 32P was distributed between two fragments, of apparent Mr 14000 (CB-1) and 28000 (CB-2). Epinephrine, vasopressin or glucagon increased the 32P content of the glycogen synthase subunit. CB-2 phosphorylation was increased by all three hormones while CB-1 was most affected by epinephrine and vasopressin. These effects correlated with a decrease in glycogen synthase activity. From studies using rat liver glycogen synthase, purified by conventional methods and phosphorylated in vitro by individual protein kinases, it was found that electrophoretically similar CNBr fragments could be obtained. However, neither cyclic-AMP-dependent protein kinase nor three different Ca2+-dependent enzymes (phosphorylase kinase, calmodulin-dependent protein kinase, and protein kinase C) were effective in phosphorylating CB-2. The protein kinases most effective towards CB-2 were the Ca2+ and cyclic-nucleotide-independent enzymes casein kinase II (PC0.7) and FA/GSK-3. The results demonstrate that rat liver glycogen synthase undergoes multiple phosphorylation in whole cells and that stimulation of cells by glycogenolytic hormones can modify the phosphorylation of at least two distinct sites in the enzyme. The specificity of the hormones, however, cannot be explained simply by the direct action of any known protein kinase dependent on cyclic nucleotide or Ca2+. Therefore, either control of other protein kinases, such as FA/GSK-3, is involved or phosphatase activity is regulated, or both.

A study of 11C-benzoate as a radiopharmaceutical for renal imaging

11C-benzoic acid prepared in a radiochemical purity over 90% was studied radiopharmacologically in mice and rabbits. The uptake of 11C-benzoate in ICR mice increased quickly. The ratio of kidney uptake rate to that in other organs reached values between 9 and 55 with a maximum at 10 min after i.v. injection. Gamma camera imaging of rabbits showed that uptake in the kidneys began at 2 min after injection and that activity began to appear in the bladder 4 min later. Rabbits with left renal artery ligature showed no uptake in the left kidney but the right kidney was imaged to the same extent as that of a rabbit without artery ligature. The kidney imaging of 11C-benzoic acid may be a useful method for renal diagnosis.

Mechanisms of serotonin-induced lymphocyte proliferation inhibition

When human peripheral blood lymphocytes were stimulated with phytohemagglutinin in the presence of serotonin, inhibition of [3H]thymidine incorporation occurred, the most marked inhibition occurring at high (10(-3)M) serotonin concentrations. This effect could not be reversed by the addition of Interleukin 2 (IL-2)-containing supernatants. Cytofluorometric analysis showed that virtually all of the cells remained in the G0 phase (unactivated) at 24 hr while some of the cells entered the G1a and G1b phases of the cell cycle by 42 hr. The cellular production of IL-2 was not affected by serotonin, as supernatants of treated cultures contained essentially the same IL-2 titers as did control cultures. Serotonin seemed to primarily affect cell activation and had little or no effect on proliferating cells. This was further confirmed by the lack of effects of serotonin on a variety of established proliferating lymphocyte, macrophage, and fibroblast cell lines. By contrast, dose-dependent inhibition of IL-2-dependent CTLL cells occurred. Serotonin was not toxic even at 10(-3) M concentrations. A marked decrease in IL-2 receptors and a change in their distribution on responder cells was seen when treated cultures were examined with the anti-Tac monoclonal antibody. At 24 hr this effect was contrastingly not seen for the OKT-8 marker, although a slight decrease in OKT-4-positive cells was seen. Serotonin thus produced an inhibition of lectin-stimulated lymphocyte proliferation via a mechanism independent of IL-2 production, and caused a decrease in the expression and distribution of IL-2 receptors on the surface of responder cells.

Antitumor activity and toxicity of ACNU, 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-1-(2-chloroethyl)-1-nitroso urea hydrochloride, comparing two divided doses and a single dose

In order to determine whether it is possible to reduce the toxicity of the nitrosoureas, including the delayed type of hematologic toxicity, without diminishing antitumor activity by administering the drug according to a new treatment schedule other than the single high-dose treatment schedule, we examined the antitumor activity against murine tumors and toxicities to host mice of a nitrosourea derivative, 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-1-(2-chloroethyl)-1- nitrosourea hydrochloride (ACNU), which was administered according to two divided doses schedule. Experimental results indicated that the toxicity of ACNU with respect to lethality, as well as weight loss of host mice, was alleviated by administering ACNU (IV) at one-half of LD10 (20 mg/kg) on 2 successive days. However, no impairment of the antitumor activity of ACNU in various murine tumor systems was observed in comparison with that of ACNU administered according to the single high-dose schedule. The delayed type of hematologic toxicity (leukopenia) could not be alleviated by this treatment schedule.

A Study of 11C-Benzoate as a Radiopharmaceutical for Renal Imaging

11C-benzoic acid prepared in a radiochemical purity over 90% was studied radiopharmacologically in mice and rabbits. The uptake of 11C-benzoate in ICR mice increased quickly. The ratio of kidney uptake rate to that in other organs reached values between 9 and 55 with a maximum at 10 min after i.v. injection. Gamma camera imaging of rabbits showed that uptake in the kidneys began at 2 min after injection and that activity began to appear in the bladder 4 min later. Rabbits with left renal artery ligature showed no uptake in the left kidney but the right kidney was imaged to the same extent as that of a rabbit without artery ligature. The kidney imaging of 11C-benzoic acid may be a useful method for renal diagnosis.

Cell cycle-related changes in number of T-lymphocyte receptors for glucocorticoids and insulin

Enriched human peripheral T-lymphocytes were stimulated with PHA and examined for variations in insulin and glucocorticoid (dexamethasone) receptor numbers during the early phases of the cell cycle. Cells in G0, G1a and G1b phases, where the G1a - G1b transition is an Interleukin 2 dependent event, were quantitated by flow cytometry. Few but significant numbers of glucocorticoid receptors (2700/cell) and no insulin receptors (-1/cell) were found in the resting (G0) phase. As cells entered the G1a phase the specific binding of dexamethasone increased and of insulin took place. Although the specific binding further increased as T-cells entered the G1b phase (as measured at 44 h of incubation and using hydroxyurea-treated cells), the major changes in the specific binding of dexamethasone took place during the period 16 - 20 h after stimulation. Based on these findings, it is concluded that both receptor types (cell membrane and cytoplasmic receptors) are being formed and increased at G1 phase prior to cell proliferation, indicating the importance of G1 phase in immunoregulation.

Transcription and translation dependent induction of interleukin 2 (IL-2) and IL-2 receptors

Our previous findings on the expression of Interleukin 2 (IL-2) receptors have shown that under the influence of certain drugs, it was possible to dissociate IL-2 production from the appearance of IL-2 receptors on human peripheral blood lymphocytes (PBL). Therefore, we studied whether the induction of IL-2 receptors were transcription- or translation-dependent. Actinomycin D and puromycin inhibited the appearance of IL-2 receptors as well as the production of IL-2. Furthermore, both drugs also inhibited human PBL to enter the G1 phase of the cell cycle. Thus, these data suggested that both IL-2 production and the appearance of IL-2 receptors were dependent on transcription and translation in non-resting cells.

Effect of gossypol on DNA synthesis and cell cycle progression of mammalian cells in vitro

Gossypol, a yellow phenolic compound extracted from cotton plants that is being used as a male antifertility drug, has been found to have cytotoxic effects. The objective of the present study was to determine the cause of these cytotoxic effects in cultured cells and to ascertain whether cells in certain phases of the cell cycle were more sensitive to the drug than were cells in other phases. HeLa or Chinese hamster ovary cells were exposed to various concentrations of gossypol for varying periods of time, and the effects of the drug on the growth rate, cell cycle traverse, plating efficiency, and macromolecular synthesis were measured. The results of this study indicate that gossypol is a specific inhibitor of DNA synthesis; it has no effect on RNA and protein synthesis at a concentration of 10 micrograms/ml and hence has no effect on the cell cycle traverse of cells from G2 to the beginning of S phase. In the presence of the drug, cells can enter S phase but fail to complete replication. The effects of the drug on growth rate and plating efficiency indicate that there is a threshold concentration at which gossypol becomes effective as a cytotoxic agent. Gossypol did not increase chromosome aberrations in the treated cells. Since gossypol irreversibly blocks cells in S phase, it could be useful as an antitumor drug.

Analysis of 3H-histamine interaction with lymphocytes: receptor binding or uptake?

The immunoregulatory role of histamine is presumably mediated by specific receptors on the plasma membrane of lymphocytes. However, using murine spleen cells and a whole cell assay commonly applied in hormone receptor studies, specific histamine receptors with an affinity higher than that of non-specific binding could not be identified. Nevertheless, approximately 30% of the totally bound histamine was undissociable over a range of added histamine concentrations (9 X 10(-6)-1 X 10(-2) M). Lectin stimulation of spleen cells caused an additional two-fold increase of undissociable histamine. The H1 receptor antagonist, diphenhydramine, blocked histamine uptake, whereas the H2 receptor antagonist, cimetidine, had no effect. Binding experiments carried out at 4 degrees C demonstrated that the amount of undissociable histamine was much reduced. Even at 4 degrees C, evidence for specific membrane associated histamine receptor could not be obtained. It was therefore concluded that lymphocytes take up histamine by an energy-dependent mechanism inhibitable by diphenhydramine but not cimetidine, and that the usual hormone receptor methodology did not allow the identification of specific membrane associated histamine receptors.

Enhanced production of hepatitis B surface antigen in NIH 3T3 mouse fibroblasts by using extrachromosomally replicating bovine papillomavirus vector

We have constructed a recombinant pBR322 plasmid composed of a subgenomic transforming fragment of bovine papillomavirus DNA and the hepatitis B surface antigen gene from cloned hepatitis B virus DNA and used it for transfection of NIH 3T3 mouse fibroblasts. The transformed cells retain the plasmids in extrachromosomal form with a copy number of about 50 to 100 per cell. Expression of the hepatitis B surface antigen gene linked to bovine papillomavirus DNA is independent of its orientation relative to the bovine papillomavirus vector. Cell lines continuously secreting high amounts of hepatitis B surface antigen into the medium could be established. The antigen is released into the culture medium as 22-nm particles, having the same physical properties and constituent polypeptides as those found in the serum of hepatitis B virus-infected patients.