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R24 is a monoclonal antibody directed against the cell surface ganglioside GD3. It can detect GD3 on the surface of a subset of T lymphocytes and can stimulate proliferation and secretion of cytokines in vitro. In the present report, we examined the effects of the R24 antibody upon antigen-specific T cell response, employing an HLA-DR7-specific T cell clonal model. As previously shown, primary stimulation of HLA-DR7-specific alloreactive T cell clones by transfectants expressing HLA-DR7 alone (t-DR7) in the absence of B7 co-stimulation resulted in anergy. Binding of cell surface GD3 on HLA-DR7-specific alloreactive T cell clones with R24 under these anergizing conditions resulted in interleukin-2 (IL-2) accumulation and prevented the induction of alloantigen-specific T cell clonal anergy. Binding of GD3 by R24 also prevented anergy under conditions where B7:CD28 interactions were blocked by CTLA4-Ig. The effect of R24 was abrogated in the presence of a combination of monoclonal antibodies for the alpha and beta chains of the IL-2 receptor (IL-2R) or a neutralizing anti-IL-2 antibody. R24 does not appear to interact directly with the IL-2R since incubation of T cell clones with R24 did not induce early activation of IL-2R associated Jak kinases, Jak1 and Jak3, as was induced following incubation with IL-2. In contrast, incubation of HLA-DR7-specific clones with t-DR7 in the presence of R24 did result in phosphorylation of IL-2R related Jak kinases after 24 h. Our data indicate that the membrane ganglioside GD3 structure recognized by R24 may play an important role in antigen-specific T cell clonal response.

Glucose is the primary stimulus for insulin secretion by pancreatic beta-cells, and it triggers membrane depolarization and influx of extracellular Ca2+. Cholinergic agonists amplify insulin release by several pathways, including activation of phospholipase C, which hydrolyzes membrane polyphosphoinositides. A novel phospholipid, phosphatidylinositol 3,4,5- trisphosphate [PtdIns(3,4,5)P3], a product of phosphatidylinositol 3-kinase (PI 3-kinase), has recently been found in various cell types. We demonstrate by immunoblotting that PI 3-kinase is present in both cytosolic and membrane fractions of insulin-secreting beta-TC3 cells and in rat islets. The catalytic activity of PI 3-kinase in immunoprecipitates of islets and beta-TC3 cells was measured by the production of radioactive phosphatidylinositol 3-monophosphate from phosphatidylinositol (PtdIns) in the presence of [gamma-32P]ATP. Wortmannin, a fungal metabolite, dose dependently inhibited PI 3-kinase activity of both islets and beta-TC3 cells, with an IC50 of 1 nmol/l and a maximally effective concentration of 100 nmol/l, when it was added directly to the kinase assay. However, if intact islets were incubated with wortmannin and PI 3-kinase subsequently was determined in islet immunoprecipitates, approximately 50% inhibition of PI 3-kinase activity (but no inhibition of glucose- and carbachol-stimulated insulin secretion) from intact islets was obtained at wortmannin concentrations of 100 nmol/l. Wortmannin, at higher concentrations (1 and 10 micromol/l), inhibited glucose- and carbachol-induced insulin secretion of Intact rat islets by 58 and 92%, respectively. Wortmannin had no effect on the basal insulin release from rat islets. A similar dose curve of inhibition of glucose- and carbachol-induced insulin secretion by wortmannin was obtained when beta-TC3 cells were used. Cellular metabolism was, not changed by any wortmannin concentrations tested (0.01-10 micromol/l). Both basal cytosolic [Ca2+]i and carbamyl choline-induced increases of [Ca2]i were unaffected by wortmannin in the presence of 2.5 mmol/l Ca2+, while Ca2+ mobilization from intracellular stores was partially decreased by wortmannin. Together, these data suggest that wortmannin at concentrations that inhibit PI 3-kinase does not affect insulin secretion. PI 3-kinase is unlikely to have a major role in insulin secretion induced by glucose and carbachol.

Interleukin 2 (IL-2) administered at low doses for prolonged periods can markedly expand the number of CD56(+) natural killer (NK) cells in patients with metastatic cancer. The cytotoxic capacity of NK cells obtained from patients receiving IL-2 in vivo can be dramatically augmented by additional exposure to IL-2 in vitro. These observations formed the basis of a clinical trial in which patients with metastatic cancer were treated with low-dose continuous daily infusions of IL-2 to increase the number of their NK cells in conjunction with intermittent boluses of additional IL-2 to stimulate this expanded pool of cytotoxic cells. Twenty-three patients were registered to receive IL-2 at 4.5 x 10(5) units/m2/day for 8 weeks by continuous i.v. infusion. After 4 weeks of "priming" with low-dose continuous infusion IL-2, cohorts of three to five patients received 5 weekly 2-h boluses of IL-2 at doses ranging from 2.5 x 10(5) units/m2 to 1.0 x 10(6) units/m2. Low-dose continuous infusion IL-2 was usually well tolerated; 2-h bolus infusions of IL-2 were often associated with high fevers and constitutional symptoms that resolved after several hours. Low-dose continuous infusion IL-2 resulted in the progressive expansion of circulating CD56(+)CD3(-) NK cells. In contrast, each bolus infusion of IL-2 resulted in an immediate dramatic decrease in both the number of NK cells and activated T lymphocytes with recovery noted within 24 h. Bolus doses of IL-2 as low as 2.5 x 10(5) units/m2 were capable of producing these effects. Cytolytic activity against NK-sensitive and -resistant targets correlated with the presence of circulating activated NK cells. Our results demonstrate that NK cells expanded by low-dose continuous infusions of IL-2 can be further activated in vivo by exposure to very low doses of IL-2 as a 2-h i.v. bolus. This capacity to manipulate human NK cells in vivo through varying the dose and schedule of IL-2 administration may help in defining the therapeutic potential of these cytotoxic effectors in the treatment of both neoplastic and infectious diseases.

It is known that transfer of the wild-type p53 gene into p53-negative cells from transgenic mice increases their sensitivity to drug and radiation-induced apoptosis. However, unlike many human tumors, these transgenic cells do not express mutant p53, and it is not known from these earlier studies whether wild-type p53 dominates the effects of mutant p53 with respect to drug and radiation sensitivity. We addressed this question in glioblastoma, a disease characterized by an unusually high level of intrinsic resistance to therapy and poor prognosis: mean survival time from diagnosis is only about 1 yr. We introduced the gene for wild-type p53 into human T98G glioblastoma cells, which express endogenous mutant p53 but not wild-type p53. Stable transfectants that co-expressed mutant and wild-type p53 had enhanced sensitivity to cisplatin and gamma radiation, compared with parental cells, control vector-transduced cells, and transduced cells that had lost expression of wild-type p53. Transient wild-type p53 expression after high-efficiency gene transfer by a p53 adenovirus also sensitized the cells to cisplatin and correlated with the induction of apoptosis. The sensitization effect was also observed in p53 adenovirus-infected H23 small cell lung carcinoma cells, which express endogenous mutant p53. Therefore, wild-type p53 gene transfer has dominant effects over mutant p53 in sensitizing tumor cells to therapy, which supports the potential of p53 gene therapy to enhance the efficacy of traditional therapy.

We have established and characterized a new glioblastoma cell line, termed GT9, from a biopsy sample of a female adult patient with glioblastoma multiforme. The line has now undergone over 60 passages and has been successfully cultured after cryopreservation. Immunofluorescence analyses with a panel of monoclonal antibodies were positive for glial fibrillary acidic protein and vimentin, and negative for neurofilament, galactocerebroside, and fibronectin, a pattern typical of glial cells. Based on a tetraploid, the composite karyotype of GT9 cells included the loss of chromosome 10, gain of chromosome 7, and the presence of double minute chromosomes, three of the most common karyotypic abnormalities in glioblastoma. Sequence analysis of p53 cDNA revealed a homozygous double mutation at codon 249 (commonly mutated in aflatoxin-associated hepatocellular carcinoma) and codon 250. Moreover, there was a complete absence of wild-type p53. However, unlike the majority of human glioblastomas previously described, the expression of platelet-derived growth factor-B (PDGF-B), a potent mitogenic autocrine factor, was low in GT9 cells. The expression and phosphorylation of c-Jun and Jun-B, downstream mediators of the PDGF pathway, were also low. Thus, deregulation of the PDGF pathway does not appear to be involved in the pathogenesis of the GT9 glioblastoma. Conversely, Jun-D, a negative regulator of cell growth, was also low. In addition, Phosphorylated Egr-1, a recently reported suppressor of PDGF-B/v-sis-transformed cells, was also low, suggesting that the lack of activation of the PDGF pathway was not due to these suppressive mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies were raised in rabbits by immunization with the heat-killed J5 mutant of Escherichia coli O111 (Rc chemotype). Serum antibodies were separated into purified IgG and IgM by sequential affinity chromatography on protein G-Sepharose and anti-rabbit IgG-Sepharose columns. J5 lipopolysaccharide (LPS)-specific IgG was prepared by affinity chromatography of purified IgG on a J5 LPS-EAH Sepharose 4B affinity column. Purified IgM, IgG, and J5 LPS-specific IgG protected neutropenic rats against lethal challenge with Pseudomonas aeruginosa 12:4:4 (Fisher Devlin immunotype 6). Nine of 16 rats treated with the IgM fraction were protected (P < .001). Thirteen of 20 rats treated with the purified IgG and 6 of 8 treated with J5 LPS-specific IgG were protected compared with none of 25 treated with IgG made from the preimmune serum of the same rabbit (P < .001). These results demonstrate that purified J5 LPS-specific IgG protects against the lethal consequences of gram-negative bacteremia.

The amount of off-site pesticide spray drift from aerial and ground applications was determined at 26 sites across Ontario. These were conducted along transects, parallel and at right angles to the flight path during aerial spray applications and at right angles to the direction of ground spray applications. All sites monitored were where commercial spray operations were in progress. The aerial applications involved both fixed wing aircraft and helicopters and the ground applications involved concentrated air-blast machines and high and low pressure boom sprayers. Deposits of spray drift outside the target area were common to all spray equipment monitored. All except low-pressure boom spraying equipment resulted in measurable spray drift to 80 m off-target with appreciable deposits up to 30-40 m. In a forest spray operation, where insecticide release was the highest, measurable residues were found up to 120 m off-target. The amount of chemical deposited off-target varied with the chemical, the climatical conditions and the equipment used. With a low-pressure boom sprayer, serious drift was confined to 9 m off-target and measurable residues to 15 m.

The markers, CD11b, CD11c, CD14, CD21, CD23, CD25, CD38, and FMC7 were correlated with morphologic and other laboratory and clinical characteristics of 127 patients with untreated CD5+ chronic lymphocytic leukemia (CLL). Only CD38 and CD21 were significantly associated with atypical CLL morphology. The integrin associated markers CD11b and CD11c were associated with lower leukocyte count (white blood cell count [WBC]) and lower Rai stage. By contrast, the activation antigen CD23 was associated with a higher WBC, higher Rai stage, younger age group, and the presence of lymphadenopathy. Therefore, we conclude that CD23 positivity may reflect a more aggressive form of CLL, and CD11b and CD11c positivity a less aggressive form. The BCL-1 gene rearrangement was present in 5 of 84 (6%) CLL cases examined and was associated with atypical morphology and surface expression of CD11b. Patients with a BCL-1 gene rearrangement may represent a CLL subset or possibly a different B-cell disease.

High resolution 2-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) combined with computerized analysis of gel images was used to search for proteins whose biosynthesis was induced or repressed in pancreatic islet cells chronically exposed to high glucose in an in situ and a tissue culture model of islet cell adaptation to excessive fuel load. The in situ model involved a 4-day intravenous infusion of either 50% glucose or 0.45% saline solution, followed by islet isolation, [35S]methionine labeling at 3 and 18 mM glucose for both groups, and protein analysis by 2-dimensional SDS-PAGE. The tissue culture model involved a 7-day culture of isolated rat islets in RPMI 1640 with 10% fetal calf serum containing either 3 or 30 mM glucose, followed by radiolabeling and 2-dimensional PAGE of proteins as in the in situ model. A small fraction of about 1.5% of the approximately 2000 identifiable proteins can be characterized as adaptive proteins. Of these altogether 58 proteins in the two models, 5 proteins were demonstrable in both models and two of these (proteins 1526 and 7622) are particularly noteworthy. Protein 1526 (Mr 57,000; pI 5.09) showed the same response pattern in both models and its expression was most enhanced when islets from chronically glucose-infused animals or those cultured for 7 days at 30 mM were radiolabeled at 18 mM glucose. Protein 7622 (Mr 68,000; pI 6.50) (also known as GSP-65; Collins, H.W., Buettger, C., and Matschinsky, F.M. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 5494-5498) showed a different labeling pattern in the two models: stimulation of [35S]methionine incorporation by 18 mM glucose both in control and experimental islets from the infusion study, but lack of such stimulation of radiolabeling in islets cultured for 7 days at 30 mM glucose in contrast to islets cultured at 3 mM. The experimental strategy and the methodology are evaluated and the significance of the results is discussed. Potentials of the approach and plans for future experiments are considered.

We have prepared aminoethyl (AE), aminopropyl (AP), and aminopentyl (APT) derivatives of gentiobiose heptaacetate (GH). These spacer compounds (AEGH, APGH, APTGH) have been coupled to succinylated diphtheria toxoid (Suc.DT) to produce conjugate vaccines. These conjugates all bind to the anti-lipid A human monoclonal antibody A6(H4C5) in an ELISA binding assay. Rabbits immunized with the APGH conjugate vaccine in either Freund's complete adjuvant or aluminum hydroxide gel produced antibody levels of 5120 and 3600 ELISA units, respectively, compared to an antibody level of less than 20 ELISA units for the prebleed sera. Sera from mice immunized with either the aminopropyl or the aminopentyl conjugate had antibody levels of 5120 and 2560 ELISA antibody units, respectively. These antibodies neutralized endotoxin in a Limulus lysate neutralization assay. Protection against the local Shwartzman reaction was demonstrated (p less than 0.05) in eight out of nine rabbits immunized with the Suc-DT-APGH conjugate vaccine compared to three out of 10 rabbits immunized with the carrier protein Suc-DT. Passive transfer experiments demonstrated that four out of five rabbits receiving immune serum were protected from Shwartzman reaction compared to one out of five rabbits receiving normal serum (p less than 0.1). These results indicated that epitopes contained in gentiobiose heptaacetate when properly presented as conjugate vaccines were capable of inducing neutralizing antibodies against endotoxin.

The effects of a Shiga toxin derived from Shigella dysenteriae Type 1, Strain 60R, and a Shiga-like toxin from the enterohemorrhagic Escherichia coli O157:H7, Strain 933, were studied in the in vivo rabbit ileal loop model. The effects of both toxins were similar and resulted in severe villus blunting by 18-24 hours after exposure. With both toxins, a dose effect was noted; and the lesions, first detected at 2 hours after inoculation, became more severe over time. Both toxins appeared to act directly and selectively on the mature columnar absorptive epithelium of the intestinal villus, which resulted in the premature expulsion of these cells from the lateral villus wall, with a decrease in the villus/crypt ratio. The goblet mucous cells remained attached and frequently formed clusters on the blunt villus apices. The crypt epithelium underwent a rapid proliferation and maintained the epithelial integrity. The ultrastructural changes observed in the toxin-injured villus absorptive cells suggested that these cells underwent a process of apoptosis, rather than necrosis. These findings suggest that both toxins act in vivo in the small intestine on a specific cell population, the mature, differentiated absorptive villus epithelium.

Fifteen hundred patients were scanned to predict fetal age and weight by biparietal diameter measurement. three hundred eleven patients had more than one scan. Forty-three small for gestational age (SGA) babies were ultimately delivered in this population. Prenatal ultrasound screening criteria for grouping into appropriate for gestational age (AGA) or small for gestational age (SGA) categories were: a) only an absolute biparietal diameter below the third percentile for the reference Rochester region population; b) only delta BPD calculated as less than 50 percent of the mean growth rate for the reference population; and c) a combination of these two factors. Intrauterine growth retardation was most accurately determined when an absolutely small biparietal diameter was found (at the time of the last ultrasound examination) in a woman with accurate gestational age assessment. Least accurate was the prediction based on one biparietal diameter measurement in a woman with poor clinical dates. A 50 percent false positive detection rate and poor sensitivity to intrauterine growth retardation were found using ultrasound biparietal diameter measurements as a screening test in this manner.

To determine the clinical importance of immunophenotypes in adult acute lymphoblastic leukemia (ALL), we prospectively studied 76 patients with this condition. Before treatment, lymphoblasts were tested for reactivity with monoclonal antibodies to B-cell, T-cell, and myeloid (My) antigens. Unexpectedly, myeloid antigens (MCS-2 or MY9) were identified in 25 patients (33 percent), usually in conjunction with B-cell or T-cell antigens. Among My+ patients, 15 (60 percent) expressed B-cell antigens (B+T-My+); all 6 tested had rearranged immunoglobulin genes. Five patients (20 percent) expressed T-cell antigens (B-T+My+), and one My+ patient expressed both B-cell and T-cell antigens. Only myeloid antigens (B-T-My+) were expressed in four patients (16 percent); three who were tested had germ-line immunoglobulin and T-cell-receptor gene configurations. Although no significant differences in presenting clinical features were found, My+ patients had fewer complete remissions than My- patients (35 vs. 76 percent, P less than 0.01). No differences in response or survival were observed between My+ and My- patients expressing T-cell antigens. However, among those expressing B-cell antigens, My+ patients had fewer complete remissions (29 vs. 71 percent, P = 0.02) and shorter survival (P = 0.03; median, 8.1 vs. greater than 26 months). These findings indicate that expression of myeloid antigen identifies a high-risk group of patients with adult ALL for whom alternative forms of treatment should be investigated.

Serum aldosterone and cortisol responses to dexamethasone were studied in 17 patients with major depressive disorder, 16 nondepressed hospitalized patients and seven healthy controls. Serum aldosterone was neither blunted nor stimulated following dexamethasone in any of these three groups. Cortisol nonsuppression following dexamethasone, based on a criterion greater than 5 micrograms/dl, was noted in five depressed patients and two nondepressed patients. None of the seven patients with cortisol nonsuppression revealed any apparent abnormalities in their serum aldosterone secretory responses following dexamethasone. Thus, the incorporation of aldosterone measurements was not a useful extension of the dexamethasone test under the clinical conditions of this study.

Mouse monoclonal antibodies that react with O-side chain specific, O-side chain cross-reactive, and core P. aeruginosa lipopolysaccharide determinants have been isolated. The monoclonals directed at O-side chain determinants are generally opsonophagocytic with human neutrophils and human complement. They also protect mice from intraperitoneal and intravenous challenge and protect in the burned rat model of infection.

Human lymphocytes derived from a lymph node draining a primary breast adenocarcinoma were fused with the mouse myeloma P3X63Ag8.653 to generate human-mouse hybridomas secreting human monoclonal antibodies (MAbs) to tumor associated antigens (TAAs). One of the resulting human MAbs, YBB 190 (IgM) is described. Enzyme-linked immunosorbent assays (ELISA) employing membrane and cytosol fractions of human tissues demonstrated YBB 190 reactivity against cytosol but not membrane components of malignant and normal epithelial tissues. When tested by an indirect immunoperoxidase staining method against fresh frozen human tissue sections, YBB 190 reacted with malignant cells in 26 of 28 epithelial cancers and with normal epithelia in 11 different benign tissues. Preliminary western blot antigen characterization indicated that YBB 190 recognizes cytokeratin intermediate filaments, or a protein that is closely associated with cytokeratins. These data indicate that B cells with specificity for intermediate filaments are present in tumor draining lymph nodes. Our findings provide insights into the nature of potential autoimmune responses in cancer patients and suggest that improved tumor directed sensitization procedures may be required to more effectively utilize lymphocytes from tumor draining lymph nodes to generate therapeutically useful human MAbs to TAAs.

The mechanisms whereby invasive enteropathogens, e.g., Salmonella typhimurium, induce intestinal secretion are largely unknown. Since these organisms penetrate the intestinal epithelium, disrupt the brush border, and evoke an acute inflammatory reaction, increased plasma filtration through a damaged, more permeable epithelium might contribute to the secretory process. To examine this possibility, the plasma-to-lumen clearance of two different sized molecules, [51Cr]albumin and [14C]mannitol, was measured in the in vivo rabbit ileal loop and in vivo rhesus monkey models of salmonellosis. In the rabbit ileal loop model, the clearance of neither molecule was increased when compared to cholera toxin-exposed loops. In the rhesus monkey, clearance of [14C]mannitol into the jejunum, ileum, and colon of Salmonella-infected animals did not differ from the observed in control animals. These data indicate that invasion of the intestinal mucosa by S. typhimurium has not substantially altered the permeability characteristics of the intestinal mucosa and that plasma filtration through a damaged, more permeable mucosa does not contribute to the Salmonella-induced intestinal secretory process.

Surface immunoglobulin (sIg) light chain analysis of peripheral blood lymphocytes (PBL) from 63 patients with non-Hodgkin's lymphoma (NHL) was performed to determine the ratio of kappa-bearing lymphocytes to lambda-bearing lymphocytes (kappa/lambda ratio). In 43% an abnormal kappa/lambda ratio was detected, implying the presence of a malignant clone in the peripheral blood (clonal excess). In 67% of cases with an abnormal kappa/lambda ratio, the absolute lymphocyte count was within normal limits and 20% did not have morphologic bone marrow involvement. Light chain analysis of bone marrow aspirates was performed in three of four patients with a circulating clone and normal bone marrow morphology. All three patients had abnormal bone marrow aspirate kappa/lambda ratios. The presence of a circulating clone was associated with morphologic bone marrow involvement (P less than 0.05). Nine patients with documented B-cell NHL were followed with repeated examinations. The presence of a circulating clone persisted in two patients refractory to therapy and in two patients otherwise believed to be in remission. Conversion to an abnormal kappa/lambda ratio occurred in two patients coincident with the development of new bone marrow involvement and in a third patient prior to the onset of frank leukemia. In three instances, the PBL light chain analyses remained within normal limits in patients with stable lymphadenopathy. The kappa/lambda ratio returned to normal in one patient responding to treatment with a partial remission, and remained within normal limits despite progression of lymphadenopathy in one patient, and local disease recurrence in another patient. These findings suggest that the detection of a circulating clone by sIg light chain analysis may be useful as a noninvasive approach to identify disseminated disease activity unsuspected on the basis of morphologic evaluations, but may not reflect the presence, progression, or recurrence of localized tissue lesions.

The effects of lead ingestion on parameters indicative of copper status, and particularly on the activity of the copper-dependent metalloenzyme superoxide dismutase (SOD) in erythrocytes, were investigated in weanling and neonatal rats. In a series of experiments, Sprague-Dawley or Long-Evans rats were fed a nutritionally adequate purified diet (AIN-'76). Lead acetate was given orally in the drinking water (0, 100, 250, or 500 ppm Pb) to groups of 23 to 26-day-old rats for 5 weeks or intragastrically (0, 5, 11, 22, or 45 mg Pb/kg body wt/day) to pups from postnatal Days 2 through 20. Lead ingestion (250 and 500 ppm Pb) by weanling rats resulted in decreased concentrations of copper in blood (erythrocytes and serum), liver, and spleen, in increased concentrations of iron in liver and spleen, in increased spleen weight, and in a small decrease in hemoglobin and hematocrit values. There was a significant decrease in the activities of the copper metalloproteins erythrocyte superoxide dismutase (SOD) and serum ceruloplasmin (Cp). In contrast, in the neonate we found no significant effects of lead on copper concentrations in blood or tissue or on other measures indicative of copper status. Despite high blood lead concentrations (1-3 micrograms/ml), SOD activity was not decreased in the neonatal rat. In addition, lead had no direct effect in vitro on the activity of bovine blood superoxide dismutase. On the basis of both the in vitro and in vivo studies, it appears likely that the observed decrease in SOD in young rats is caused indirectly by a lead-induced copper deficiency rather than by a direct inhibitory effect of lead.

In spite of several macroscopic criteria for predicting the presence of histological abnormalities in rabbit ileum, microscopic ileal abnormalities still can escape detection. The effect of histologically abnormal rabbit ileum was evaluated on basal intestinal absorption, on basal absorption, on basal adenylate cyclase activity, and on cholera toxin-induced secretion and cholera toxin-induced stimulation of adenylate cyclase activity. Compared to histologically normal rabbit ileum, the presence of histological abnormalities was associated with decreased basal intestinal water, Na, Cl, and glucose absorption, absent glucose-dependent water absorption, and elevated basal adenylate cyclase activities. However, histologically abnormal rabbit ileum responded to inoculation of purified cholera toxin with stimulation of intestinal water secretion and adenylate cyclase activity similar to that in histologically normal ileum. These data have implications concerning the design of experiments that attempt to study the pathogenesis of diarrheal diseases by correlating changes in ileal transport with changes in ileal mucosal adenylate cyclase activity. In spite of abnormal ileal histology, studies of intestinal secretory states which attempt to define the role of adenylate cyclase in secretory processes can be performed provided animals are used as their own controls. However, when groups of animals are compared, the presence of an histologically abnormal ileum can cause changes in basal and intestinal secretagogue-stimulated ileal water and electrolyte transport and in basal and intestinal secretagogue-stimulated mucosal adenylate cyclase activity which can lead to erroneous conclusions if the presence of the abnormal ileal histology is not considered.

Strains of Salmonella typhimurium were studied in the ligated rabbit ileal loop model to gain insight into the mechanisms whereby bacteria which invade the gastrointestinal mucosa evoke fluid exsorption. The organisms employed differed in various biologic attributes including the ability to invade the ileal epithelium, multiply within the mucosa, elicit an acute inflammatory reaction, and disseminate across the intestinal wall. Some strains provoked small intestinal fluid exsorption although these did not elaborate enterotoxin. Only those strains which invaded the mucosa were accompanied by either mucosal inflammation or fluid exsorption. Noninvasive strains produced neither histologic abnormalities nor fluid secretion. While strains which invaded the mucosa caused an acute inflammatory reaction, not all such strains evoked fluid secretion. Furthermore, there was no correlation in ability of invasive organisms to evoke fluid secretion or in the intensity of mucosal inflammation, number of intramucosal salmonellae, or in ability to disseminate from the rabbit ileum. These observations suggest that, as is the case in shigellosis, mucosal invasion may be a necessary factor for the intestinal fluid loss in salmonellosis. A bacterial property or factor, in addition to invasion of the gastrointestinal mucosa, seems to be responsible for fluid exsorptin. However, it is unlikely that a salmonella enterotoxin comparable to that elaborated by Vibrio cholerae, toxigenic Escherichia coli, or Shigella dysenteriae 1 is related to fluid secretion in salmonellosis.