Forkhead box protein 3(+) regulatory T cells and Helios(+) subset in perinatally acquired HIV.

Forkhead box protein 3 (FoxP3)(+) regulatory T cells (Tregs ) are important not only in regulating the development of autoimmune conditions, but also in chronic infectious diseases. Given their cardinal function in suppressing immune activation, research has focused upon whether they play a detrimental role in chronic infections, particularly HIV. While the role of Tregs in HIV has been investigated intensively, it remains an unresolved topic. However, it is generally accepted that Tregs are susceptible to HIV infection and are preferentially preserved over conventional CD4(+) T cells. It is unknown whether the peripheral-induced or the thymic-derived Tregs are more susceptible to HIV cytotoxicity. It has been recognized that Tregs can be segregated into two subsets based on Helios expression, with the vast majority being Helios(+) . This study examines the impact of HIV infection on total Tregs and their Helios subsets in a perinatal-acquired HIV-infected paediatric population. The finding indicates a selective expansion or survival of Tregs in association with CD4 depletion and increased viraemia. The Helios(+) and Helios(-) subsets within Tregs appear to be equally affected. However, the Helios(+) Tregs seem to be more preserved in patients with low CD4(+) ≤ 25% and detectable plasma HIV RNA >20 copies/ml. In this group, the frequencies of Tregs are increased, but their numbers appear insufficient to restrain immune activation. In conclusion, our findings suggest that both Helios subsets of Tregs are susceptible to HIV infection and are preferentially preserved compared to conventional CD4(+) T cells.

Investigation of Localized Skin Temperature Distribution Across the Transtibial Residual Limb.

BACKGROUND: Interventions to resolve thermal discomfort as a common complaint in amputees are usually chosen based on the residual limb skin temperature while wearing prosthesis; whereas, less attention has been paid to residual limb skin temperature while outside of the prosthesis. The objective of this study was to explore the localized and regional skin temperature over the transtibial residual limb (TRL) while outside of the prosthesis. METHODOLOGY: Eight unilateral transtibial adults with traumatic amputation were enrolled in this cross-sectional study. Participants sat to remove their prostheses and rested for 30 minutes. Twelve sites were marked circumferentially in four columns (anterolateral, anteromedial, posteromedial, and posterolateral) and longitudinally in three rows (proximal, middle, and distal) over the residual limb and used for attachment of analog thermistors. Skin temperature was recorded and compared for 11 minutes. Furthermore, the relationship of skin temperature with participants' demographic and clinical characteristics was explored. FINDINGS: The whole temperature of the TRL was 27.73 (SD=0.83)°C. There was a significant difference in skin temperature between anterior and posterior columns. Likewise, the distal row was significantly different from the proximal and middle rows. The mean temperature at the middle and distal zones of the anteromedial column had the highest and lowest skin temperatures (29.8 and 26.3°C, p<0.05), respectively. The mean temperature of the whole TRL had no significant relationships (p>0.05) with participants' demographic and clinical characteristics. CONCLUSIONS: An unequal distribution of temperature over the TRL was found with significantly higher and lower temperatures at its anterior column and distal row, respectively. This temperature pattern should be considered for thermoregulation strategies. Further investigation of the residual limb temperature with and without prosthesis, while considering muscles thickness and blood perfusion rate is warranted.

Interleukin 2 receptor-targeted cytotoxicity. Interleukin 2 receptor-mediated action of a diphtheria toxin-related interleukin 2 fusion protein.

The IL-2 toxin-mediated inhibition of protein synthesis in high affinity IL-2-R-positive murine and human T cell lines has been examined. Both excess free IL-2 and mAb to the Tac epitope of the p55 subunit of IL-2-R are shown to block the action of IL-2 toxin; whereas, agents that interact with other receptors or antigens on the T cell surface have no effect. We show that IL-2 toxin, like diphtheria toxin, must pass through an acidic vesicle in order to intoxicate target T cells. Finally, we demonstrate that the IL-2 toxin-mediated inhibition of protein synthesis in both human and murine T cells that bear the high affinity IL-2-R is due to the classic diphtheria toxin fragment A-catalyzed ADP ribosylation of elongation factor 2.

The interrelationship of complement-activation fragments and angiogenesis-related factors in early pregnancy and their association with pre-eclampsia.

OBJECTIVE: To determine the interrelationships during early pregnancy of complement-activation fragments Bb, C3a and sC5b-9, and angiogenesis-related factors placental growth factor (PiGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng), and their associations with pre-eclampsia. DESIGN: Prospective cohort study. SETTING: Denver complement study (June 2005-June 2008). POPULATION: A total of 668 pregnant women with singleton gestations, recruited between 10 and 15 weeks of gestation. METHODS: Using univariable and multivariable logistic regression analysis, concentrations of complement-activation fragments and angiogenesis-related factors were compared between 10 and 15 weeks of gestation in women who subsequently did or did not develop pre-eclampsia. Interrelationships between these variables were tested using the non-parametric Spearman rank correlation coefficient. MAIN OUTCOME MEASURE: Pre-eclampsia. The association of complement-activation fragments and angiogenesis-related factors with obesity was also examined. RESULTS: The mean (+/-SD) levels of complement Bb in early pregnancy among women who did and did not develop pre-eclampsia were 0.84 (+/-0.26) microg/ml and 0.69 (+/-0.2) microg/ml, respectively (P = 0.001). Concentrations of PiGF were significantly (P = 0.01) lower (31 +/- 12 pg/ml) in early pregnancy in the pre-eclamptic group of women, as compared with the normotensive group (39 +/- 32 pg/ml). The adjusted odds ratio (AOR) of Bb and PiGF were 2.1 (CI = 1.4-3.1, P < 0.0003) and 0.2 (CI = 0.07-0.7, P = 0.01), respectively. There was no significant difference in the levels of C3a, sC5b-9, sFlt-1 and sEng in early pregnancy among women who developed pre-eclampsia, compared with women who remained normotensive during pregnancy. Higher levels of Bb (P = 0.0001) and C3a (P = 0.03), and lower levels of sFlt-1 (P = 0.0002) and sEng (P = 0.0001) were found among women with obesity, compared with non-obese controls. No meaningful relationships were found between the complement-activation fragments and the angiogenesis-related factors. CONCLUSIONS: In this cohort during early pregnancy, increased concentrations of complement-activation factor Bb and lower concentrations of PiGF were associated with the development of pre-eclampsia later in pregnancy.

Cloned fragment A of diphtheria toxin is expressed and secreted into the periplasmic space of Escherichia coli K12.

An 831-base pair segment of the corynebacteriophage beta tox-45 genome encoding fragment A of diphtheria toxin was cloned into plasmid pUC8 in Escherichia coli K12. Strains containing recombinant plasmids expressed the adenosine diphosphate ribosyl transferase activity characteristic of fragment A; this activity could be inhibited by polyvalent antiserum to fragment A as well as by the appropriate monoclonal antibodies to diphtheria toxin. The transferase activity was secreted into the periplasmic space of E. coli. These findings have implications for the future construction of genetically engineered chimeric toxins.

Selective elimination of HIV-1-infected cells with an interleukin-2 receptor-specific cytotoxin.

Infection by human immunodeficiency virus type 1 (HIV-1) is associated with cellular activation and expression of the interleukin-2 (IL-2) receptor. A genetically engineered fusion toxin, DAB486 IL-2, that contains the enzymatic site and translocation domain of diphtheria toxin and the receptor binding domain of IL-2 specifically kills cells that express high-affinity IL-2 receptors. This toxin selectively eliminated the HIV-1-infected cells from mixed cultures of infected and uninfected cells and inhibited production of viral proteins and infectious virus. Thus, cellular activation antigens present a target for early antiviral intervention.

Nucleotide sequence and expression of the diphtheria tox228 gene in Escherichia coli.

The complete nucleotide sequence of the diphtheria tox228 gene encoding the nontoxic serologically related protein CRM228 has been determined. A comparison of the predicted amino acid sequence with the available amino acid sequences from the wild-type toxin made it possible to deduce essentially the entire nucleotide sequence of the wild-type tox gene. The signal peptide of pro-diphtheria toxin and the putative tox promoter have been identified, a highly symmetrical nucleotide sequence downstream of the toxin gene has been detected; this region may be the corynebacteriophage beta attachment site (attP). The cloned toxin gene was expressed at a low level in Escherichia coli.

The Mars Pathfinder atmospheric structure investigation/meteorology (ASI/MET) experiment.

The Mars Pathfinder atmospheric structure investigation/meteorology (ASI/MET) experiment measured the vertical density, pressure, and temperature structure of the martian atmosphere from the surface to 160 km, and monitored surface meteorology and climate for 83 sols (1 sol = 1 martian day = 24.7 hours). The atmospheric structure and the weather record are similar to those observed by the Viking 1 lander (VL-1) at the same latitude, altitude, and season 21 years ago, but there are differences related to diurnal effects and the surface properties of the landing site. These include a cold nighttime upper atmosphere; atmospheric temperatures that are 10 to 12 degrees kelvin warmer near the surface; light slope-controlled winds; and dust devils, identified by their pressure, wind, and temperature signatures. The results are consistent with the warm, moderately dusty atmosphere seen by VL-1.

Hemoglobin CC disease: rheological properties or erythrocytes and abnormalities in cell water.

Suspensions of erythrocytes from patients with hemoglobin (Hb) CC disease showed an increased viscosity and decreased filterability suggesting a less deformable cell. Hemolysates prepared from Hb CC erythrocytes had an increased viscosity compared with hemolysates of normal cells, suggesting that the increased viscosity of Hb CC cells in serum was the result of an increased internal viscosity of the cell. These abnormal rheological properties of Hb CC erythrocytes were associated with a decreased content of cations and an abnormality of cell water. The fraction of the cell volume, which is water in Hb CC cells, was 95.5% of normal. The amount of cell water in Hb CC cells available for osmotic equilibrium, termed solvent water, was only 67% of that in normal cells. The smaller amount of solvent water in Hb CC cells indicates a greater amount of water bound to protein. Altered rheological properties of erythrocytes with Hb AA, CC, and SC also were observed during pregnancy. Suspensions of erythrocytes in serum or plasma from pregnant patients resulted in an increased viscosity compared with suspension in serum or plasma from nonpregnant individuals. An increased viscosity during pregnancy is consistent with the increased severity of the hemolytic anemia in patients with these hemoglobinopathies during pregnancy. The studies reported here suggest that in Hb CC disease the mechanism of erythrocyte destruction, splenic sequestration, results from the increased viscosity, and less deformability of the erythrocyte with on increased internal viscosity.

Safety, infectivity, immunogenicity, and in vivo stability of two attenuated auxotrophic mutant strains of Salmonella typhi, 541Ty and 543Ty, as live oral vaccines in humans.

Two Salmonella typhi mutants, 541Ty (Vi+) and 543Ty (Vi-), auxotrophic for p-aminobenzoate and adenine, were evaluated as live oral vaccines. 33 volunteers ingested single doses of 10(8), 10(9), or 10(10) vaccine organisms, while four others received two 2 X 10(9) organism doses 4 d apart. No adverse reactions were observed. Vaccine was recovered from coprocultures of 29 of 37 vaccinees (78%) and from duodenal string cultures of two; repeated blood cultures were negative. The humoral antibody response to S. typhi O, H, Vi, and lysate antigens in serum and intestinal fluid was meager. In contrast, all vaccinees manifested cell-mediated immune responses. After vaccination, 69% of vaccinees overall and 89% of recipients of doses greater than or equal to 10(9) responded to S. typhi particulate or purified O polysaccharide antigens in lymphocyte replication studies but not to antigens of other Salmonella or Escherichia coli. All individuals, postvaccination, demonstrated a significant plasma-dependent mononuclear cell inhibition of wild S. typhi.

Protein engineering and design for drug delivery.

Over the past decade considerable effort has been focused on the genetic construction, expression, and characterization of fusion proteins designed to selectively target specific disease-causing cells and/or extracellular targets. In each instance, the coding sequences for the functional domains of different proteins have been genetically fused, resulting in the formation of fusion proteins which retain the function of their component segments. As anticipated from their design, many of these fusion proteins offer a marked therapeutic advantage over conventional agents in preclinical studies. While several recombinant fusion proteins have entered or will shortly begin Phase I/II human clinical trials, the first of these fusion proteins is currently being evaluated in Phase III human clinical trials for the treatment of cutaneous T cell lymphoma.

Trojan horse or proton force: finding the right partner(s) for toxin translocation.

Much is known about the structure function relationships of a large number of bacterial protein toxins, the nature of their cell surface receptors, and their enzymatic activities which lead to the inactivation of their respective cytosolic targets. Despite this wealth of knowledge a detailed understanding of the mechanisms which underlie translocation of the catalytic domain across the eukaryotic cell membrane to the cytosol, the penultimate event in the intoxication process, have been slow in developing. In the case of diphtheria toxin, two prominent hypotheses have been advanced to explain how the catalytic domain is translocated from the lumen of endocytic vesicles to the target cell cytosol. We discuss each of these hypotheses and provide an overview of recent observations that tend to favor a mechanism employing a Cytosolic Translocation Factor complex in the entry process. This facilitated mechanism of translocation appears to rely upon protein-protein interactions between conserved domains within the transmembrane domain of diphtheria toxin with host cell factors to effect delivery of the enzymatic moiety. We have recently identified a 10 amino acid motif in the transmembrane domain of diphtheria toxin that is conserved in anthrax Lethal and Edema Factors, as well as in botulinum neurotoxins A, C and D. Stable eukaryotic cell transfectants that express a peptide containing this motif become resistant to the toxin, and sensitivity is completely restored by co-expression of siRNA which inhibits peptide expression. Data obtained from use of the protein fusion toxin DAB(389)IL-2 in cytotoxicity assays using susceptible Hut 102/6TG and resistant transfectant Hut102/6TG-T1 cells, as well as pull down assays have led to the formulation of a working model of facilitated delivery of the diphtheria toxin catalytic domain to the cytosol of target cells which is discussed in detail.

Fluorescence versus white-light bronchoscopy for detection of preneoplastic lesions: a randomized study.

BACKGROUND: There are no currently approved methods for the screening and early detection of lung cancer. We compared the ability of conventional white-light bronchoscopy (WLB) and laser-induced fluorescence endoscopy (LIFE) to detect preneoplastic lung lesions in a randomized trial in which both the order of the procedures and the bronchoscopists were randomly assigned. METHODS: The study included high-risk subjects enrolled because of a cigarette smoking history of at least 30 pack-years, an air-flow obstruction, and either an abnormal sputum cytology (n = 48) or a previous or suspected lung cancer (n = 7). LIFE and WLB were performed on all patients. Biopsy specimens were assessed for histologic abnormalities, including the presence of angiogenic squamous dysplasia. All statistical tests were two-sided. RESULTS: A total of 391 biopsy specimens were taken from the 55 patients. Thirty-two patients (58%; 95% confidence interval [CI] = 44% to 71%) had at least one biopsy with moderate or severe dysplasia, and 19 (59%; 95% CI = 41% to 76%) of these patients could be diagnosed based solely on the results of LIFE. LIFE was statistically significantly more sensitive than WLB for detecting moderate dysplasia or worse (68.8% versus 21.9%, respectively) (difference = 46.9%; 95% CI = 25% to 68%; P< .001). The relative sensitivities (WLB = 1.0) were 3.1 (95% CI = 1.6 to 6.3) for LIFE and 3.7 (95% CI = 1.9 to 7.3) for LIFE and WLB combined. LIFE was less specific than WLB (69.6% versus 78.3%, respectively; P = .45), but the difference was not statistically significant. The relative specificities (WLB = 1.0) were 0.9 for LIFE (95% CI = 0.6 to 1.3) and 0.6 (95% CI = 0.4 to 1.0) for LIFE and WLB combined. The results were similar regardless of the order of the procedures or the order of the bronchoscopists. Also, LIFE was better at identifying angiogenic squamous dysplasia lesions than WLB (detection ratio [DR], which indicates the relative likelihood of getting a positive result in a sample with dysplasia compared with one without, for LIFE = 1.39 [95% CI = 1.17 to 1.65] versus DR for WLB = 0.67 [95% CI = 0.38 to 1.21]). CONCLUSION: LIFE was more sensitive than WLB in detecting preneoplastic bronchial changes in high-risk subjects. The prognostic implication of this finding is not yet clear.

Inhibition of protein synthesis in small cell lung cancer cells induced by the diphtheria toxin-related fusion protein DAB389 GRP.

DAB389 GRP is composed of the catalytic and transmembrane domains of diphtheria toxin fused to gastrin-releasing peptide (GRP). DAB389 GRP is selectively targeted to, and inhibits protein synthesis in, cell lines expressing GRP receptors. Protein synthesis in 5'ET4 cells (BALB/3T3 fibroblasts transfected with the gene encoding the GRP receptor) was inhibited by 50% in the presence of 20 pM DAB389 GRP (IC50, 20 pM). DAB389 GRP did not inhibit protein synthesis in untransfected BALB/3T3 cells. A second neuropeptide-conjugated toxin, DAB389 SP, directed to cells expressing substance P receptors, was not cytotoxic to 5'ET4 cells, nor was DAB389 GRP cytotoxic to substance P receptor-bearing cells. DAB389 GRP cytotoxic effects were receptor specific and were inhibited either by excess GRP or anti-GRP antibody. Cytotoxicity was mediated by passage through an acidic vesicle, because addition of 10 microM chloroquine to the reaction inhibited cytotoxicity. DAB389 GRP and DAB389 SP were tested on a number of tumor cell lines. DAB389 GRP inhibited protein synthesis in AR42J rat pancreatic acinar cells and HuTu 80 human duodenal adenocarcinoma cells with IC50s of 65 and 200 pM, respectively. DAB389 SP had an IC50 of 9.5 pM for the AR42J cells and 12 nM for the HuTu 80 cell line. A number of small cell lung cancer cell (SCLC) lines were tested, and the IC50 for DAB389 GRP ranged from 1.1 to 85 nM. Sensitivity to DAB389 GRP appeared to be based on receptor number and receptor type (i.e., GRP or neuromedin B preferring). SCLC cells were also sensitive to DAB389 SP, with IC50s ranging from 2.4 to 11.5 nM. These results suggest that a potential use exists for diphtheria-based fusion toxins as therapeutic agents for treatment of SCLC and other neuropeptide receptor-bearing cancers.

Imaging of non-small cell lung cancers with a monoclonal antibody, KC-4G3, which recognizes a human milk fat globule antigen.

To determine the role of lung cancer tumor imaging with monoclonal antibodies directed against high molecular weight human milk fat globule antigens, we administered i.v. 111In-KC-4G3 to 24 patients with advanced non-small cell lung cancer. One mg of 111In-KC-4G3 was mixed with 0, 9, 49, 99, or 499 mg of unlabeled KC-4G3 and infused i.v. over 1 to 5 h. The mean 111In-KC-4G3 radiochemical purity was greater than 97% and the resultant immunoreactivity averaged 62%. Successful imaging of cancer sites was accomplished in 92% of 24 patients, and 57% of 91 total lesions were visualized. Successful localization of tumor sites related to size (P less than 0.001), with 81% of lesions greater than 3.0 cm in diameter, 50% of lesions 1.5 to 3 cm, and 6% of lesions less than 1.5 cm successfully imaging, and to location (P less than 0.05), with 69% of pulmonary lesions, 80% of soft tissue lesions, and only 32% of bone metastases being visualized. Nonspecific reticulo-endothelial uptake of radioactivity was a major problem. Approximately 35% of 111In was chelated to serum transferrin by 24 and 48 h after infusion. The mean t 1/2 beta for plasma radioisotope and immunoreactive KC-4G3 was 29 and 27 h, respectively. There was no correlation between total infused antibody dose and imaging success or between total dose and effect on 111In and KC-4G3 kinetics. Circulating free KC-4 antigen was measurable in all but one patient before study. Tumor biopsy following infusion could demonstrate antibody presence but not saturable antigen binding. We conclude that (a) 111In-KC-4G3 demonstrates successful tumor localization in non-small cell lung cancers bearing generally high expression of its antigen and (b) further investigations to diminish nonspecific radioactivity for imaging and utilization of high dose radiolabeled antibody for therapeutic intent are warranted.

beta-Carotene inhibits rectal mucosal ornithine decarboxylase activity in colon cancer patients.

Colonic adenocarcinoma affects approximately 6% of adults in many Western countries. beta-Carotene (BC), a safe, inexpensive, and widely available compound, has been proposed as a cancer chemopreventive agent. To evaluate whether BC shows promise as an inhibitor of colonic carcinogenesis, we studied 20 male subjects who had previously undergone resection of colonic adenocarcinoma. Each subject received beta-carotene, 30 mg orally, daily for 6 months. Rectal mucosa was sampled at multiple intervals prior to, during, and following BC administration. Mucosal ornithine decarboxylase (ODC) activity and serum and mucosal BC concentrations were determined at each interval. ODC activity was inhibited by 44% (P < 0.05) and 57% (P < 0.01) after 2 and 9 weeks, respectively, of BC administration and remained low compared with baseline even 6 months following discontinuation of BC. Serum and mucosal BC concentrations increased as expected during BC administration and remained elevated for 6 months following BC discontinuation. The demonstrated inhibition of rectal mucosal ODC activity in these patients with resected colon cancer suggests that BC may prove useful as a cancer chemopreventive agent.

Interaction of an alpha-melanocyte-stimulating hormone-diphtheria toxin fusion protein with melanotropin receptors in human melanoma metastases.

A hybrid toxin targeted to melanotropin receptors and selectively cytotoxic to melanoma cell lines in vitro has recently been developed. The toxin, a recombinant fusion protein (designated DAB389-MSH), contains the peptide sequences of alpha-melanocyte-stimulating hormone (alpha-MSH) and the catalytic (cytotoxic; Fragment A) and lipophilic (part of Fragment B) domains of diphtheria toxin. In the present study, binding of DAB389-MSH to melanotropin receptors in biopsy specimens of human and mouse melanoma metastases was assessed by measuring its ability to inhibit binding of a radiolabeled, superpotent analogue of alpha-MSH (125I-[Nle4,D-Phe7]-alpha-MSH; 125I-NDP-MSH) and comparing its potency in this system with those of the established ligands NDP-MSH and alpha-MSH. Radioligand binding to tissue sections in vitro was localized and quantified by autoradiography and image analysis. DAB389-MSH inhibited binding of 125I-NDP-MSH to experimental murine B16-F1C23 melanoma metastasis tissue and to melanoma metastases of three patients. In both mouse and human melanoma tissues, concentration-response relationships for DAB389-MSH-mediated inhibition of 125I-NDP-MSH binding were parallel, and its maximal effects were comparable in magnitude, to those of NDP-MSH and alpha-MSH. Half-maximal peptide concentrations for inhibition of 125I-NDP-MSH binding to mouse melanoma tissue sections were: NDP-MSH, 0.63 nM; alpha-MSH, 3.14 nM; and DAB389-MSH, 10.1 nM. In human melanoma tissues, the respective half-maximal peptide concentrations for inhibition of 125I-NDP-MSH binding to mouse melanoma tissue sections were: NDP-MSH, 1.80 nM; alpha-MSH, 2.43 nM; and DAB389-MSH, 11.9 nM. Taken together, these results suggest that NDP-MSH, alpha-MSH, and DAB389-MSH bind to a common melanotropin receptor in human metastatic melanoma cells. Since previous work has shown that melanotropin receptors are detectable in melanoma metastases of about 80% of human patients, malignant melanoma cells of many patients may be susceptible to killing by the melanotropin receptor-targeted cytotoxin DAB389-MSH.

Cytotoxicity of interleukin 2-toxin toward lymphocytes from patients with adult T-cell leukemia.

The inhibitory effect of a diphtheria toxin-related interleukin 2 fusion protein, IL-2-toxin, on protein synthesis in adult T-cell leukemia/lymphoma (ATL) cells was examined in vitro. Peripheral blood ATL cells from 12 patients (six acute type, four chronic type, and two smoldering type ATL) and the lymph node cells from three ATL patients (two acute type and one lymphoma type ATL) were examined. At a concentration of 10(-8) M, IL-2-toxin inhibited protein synthesis by 60 to 98% in lymph node ATL cells, whereas protein synthesis in peripheral blood ATL cells was inhibited from 20 to 57% in acute type, and from 3 to 13% in chronic type. In contrast, IL-2-toxin had no measurable effect on T-cells from either patients with smoldering type ATL or normal controls. The cytopathic effects of IL-2-toxin were blocked by the addition of anti-CD25 monoclonal antibody, suggesting that the inhibition of protein synthesis in target cells was mediated by the IL-2 receptor (IL-2R). The degree of inhibition of protein synthesis, however, was not closely correlated with expression of CD25 antigen (low-affinity Mr 55,000 glycoprotein, IL-2R, Tac antigen) on ATL cells. There was an apparent correlation between the degree of inhibition and the rate of protein synthesis in ATL cells. We demonstrate that ATL cells from patients with acute or lymphoma type disease were more sensitive to IL-2-toxin than cells from chronic or smoldering disease. These findings suggest that the high affinity IL-2R present on acute and lymphoma type ATL cells may serve as a target for therapy with this recombinant chimeric toxin.

Prostate cancer and other xenografts from cells in peripheral blood of patients.

Good models for the investigation of human prostate cancer are few. Cells from approximately 9.2-21 ml of peripheral blood from patients with metastatic prostate cancer or metastatic colon cancer were injected s.c. into nude mice. Prostate cancer from 2 of 11 patients and colon cancer from 1 of 3 patients were found to be growing as metastases in the lungs of the nude mice. To our knowledge, this is the first report of the formation of xenografts from carcinoma cells taken directly from the peripheral blood of patients. Expanding circulating cancer cells with this approach may have important translational applications including: (a) development of models of human cancers; and (b) sampling of cancers from specific patients for novel molecular and therapeutic approaches.

Crystallization and preliminary X-ray studies of the diphtheria Tox repressor from Corynebacterium diphtheriae.

Crystals of the diphtheria tox repressor (DtxR) from Corynebacterium diphtheriae suitable for structure determination have been obtained. DtxR activated with transition metal ions represses the expression of the structural gene for the diphtheria toxin, tox, which is encoded on the genome of a family of closely related corynebacteriophages. The space group of the obtained crystals is trigonal P3(1)21 or its enantiomorph P3(2)21 with a = b = 64.2 A, c = 220.5 A, alpha = beta = 90 degrees, gamma = 120 degrees. Two monomers comprise the asymmetric unit. The crystals diffract to a resolution of better than 3 A.