Anhedonia and anergia predict mortality in older Australians living in residential aged care

OBJECTIVES

Depression is common in older adults and is linked to morbidity and mortality. The aim of this study was to investigate whether specific symptoms of depression (dysphoria, anhedonia and anergia) predicted mortality in older Australian Aged Care residents.

METHODS

Eighty older adults (M = 83.16 ± 7.14) without cognitive impairment residing in 14 Residential Aged Care facilities located in Melbourne, Australia, completed the 15-item Geriatric Depression Scale-Short Form (GDS-15) and the Standardized Mini Mental State Examination. Residential Aged Care facilities provided the primary end-point of all-cause mortality at follow-up (M = 5.4 years ± 0.1).

RESULTS

Univariate Kaplan-Meier survival curves and Cox Proportional Hazards regression analyses were used to evaluate whether symptoms of depression predicted all-cause mortality, with known prognostic factors controlled. The results indicated that anhedonia (Hazard Ratio = 2.931 [95% CI 1.278-6.722], p = .011) and anergia (Hazard Ratio = 2.783 [95% CI 1.065-7.276], p = .037) were associated with almost a threefold increased risk of mortality in older adults living in RAC in adjusted analyses. Dysphoria did not predict mortality.

CONCLUSIONS

These findings advance understanding of the mortality risks of anhedonia and anergia in an understudied population. Symptoms of anhedonia and anergia should be targeted for screening in older adults living in Aged Care to increase the detection and potential for referral to treatment for depressive presentation.

Farmer and Public Attitudes Toward Lamb Finishing Systems

To develop research and policy on the welfare of lambs in intensive finishing systems, it is important to understand public and sheep farmers' attitudes. The aim of this research was to identify and compare farmer and community attitudes relevant to the intensification of lamb finishing. The majority of respondents in the community sample expressed concern about all listed welfare issues, but particularly about feedlotting of lambs and the associated confinement. These attitudes correlated with community views on the importance of welfare issues including social contact and freedom to roam. Farmers expressed much lower levels of concern than did the general public except with regard to the health of lambs, disease control, access to shade, and lack of access to clean water.

The 'real world' utility of a web-based bipolar disorder screening measure

OBJECTIVE

To determine whether those completing a self-report bipolar self-test measure and identified as having a likely bipolar disorder judged the self-test as useful and had a subsequent superior illness course.

METHOD

We invited those completing the web-based Mood Swings Questionnaire (or MSQ) to provide contact details and contribute to a 3-month study evaluating their responses to being identified as having a likely bipolar disorder, any subsequent action taken and the impact of such actions on their illness trajectory.

RESULTS

We analysed data received from 665 participants screening 'positive' on the MSQ and completing baseline and 3-month follow-up data. High rates of satisfaction with the MSQ were quantified, with respondents viewing the measure as informative, validating and/or motivating. Of those receiving a confirmed bipolar diagnosis, such clarification occurred on average 12 years after their first depressive episode. Most implemented self-management strategies irrespective of whether seeking formal diagnostic clarification or not. Participants improved on depressive, quality of life and overall functioning measures over the study period, but with results indicating (via analysis of three sample subsets differing by the degree of 'actions taken') that those who took assertive action and had the diagnosis confirmed had the most superior outcome.

CONCLUSION

This is the first study to formally evaluate the clinical impact of a self-report bipolar disorder screening measure. High acceptance and superior outcomes quantified for those acting assertively in response to such a new diagnosis argue for its 'real world' utility.

Category fluency test: normative data for English- and Spanish-speaking elderly

Category fluency tasks are an important component of neuropsychological assessment, especially when evaluating for dementia syndromes. The growth in the number of Spanish-speaking elderly in the United States has increased the need for appropriate neuropsychological measures and normative data for this population. This study provides norms for English and Spanish speakers, over the age of 50, on 3 frequently used measures of category fluency: animals, vegetables, and fruits. In addition, it examines the impact of age, education, gender, language, and depressed mood on total fluency scores and on scores on each of these fluency measures. A sample of 702 cognitively intact elderly, 424 English speakers, and 278 Spanish speakers, participated in the study. Normative data are provided stratified by language, age, education, and gender. Results evidence that regardless of the primary language of the examinee, age, education, and gender are the strongest predictors of total category fluency scores, with gender being the best predictor of performance after adjusting for age and education. English and Spanish speakers obtained similar scores on animal and fruit fluency, but English speakers generated more vegetable exemplars than Spanish speakers. Results also indicate that different fluency measures are affected by various factors to different degrees.

Intraventricular immunotoxin therapy for leptomeningeal neoplasia

OBJECTIVE

The goals of this clinical trial of intraventricular 454A12-rRA therapy were to identify dose-limiting toxicities, to evaluate the pharmacokinetics of single-dose intraventricular 454A12-rRA, and to detect antitumor activity.

METHODS

We performed a pilot study of intraventricular therapy with the immunotoxin 454A12-rRA in eight patients with leptomeningeal spread of systemic neoplasia. The immunotoxin 454A12-rRA is a conjugate of a monoclonal antibody against the human transferrin receptor and recombinant ricin A chain, the enzymatically active subunit of the protein toxin ricin. Patients were treated with single doses of 454A12-rRA ranging from 1.2 to 1200 micrograms.

RESULTS

The early phase half-life of 454A12-rRA in ventricular cerebrospinal fluid (CSF) averaged 44 +/- 21 minutes, and the late phase half-life averaged 237 +/- 86 minutes. The clearance of the immunotoxin was faster than the clearance of coinjected technetium-99m-diethylenetriamine penta-acetic acid, averaging approximately 2.4-fold greater. No 454A12-rRA degradation was detected by Western blot analysis of ventricular CSF for a period of 24 hours, and bioactivity was retained in CSF paralleling the concentration of immunotoxin. No acute or chronic drug toxicity was identified in patients who received less than or equal to 38 micrograms of 454A12-rRA by intraventricular injection. Doses more than or equal to 120 micrograms caused a CSF inflammatory response that was associated with transient headache, vomiting, and altered mental status. This acute syndrome was responsive to steroids and CSF drainage. No systemic toxicity was detected. In four of the eight patients, a greater than 50% reduction of tumor cell counts in the lumbar CSF occurred within 5 to 7 days after the intraventricular dose of 454A12-rRA; however, no patient had their CSF cleared of tumor, and clinical or magnetic resonance imaging evidence of tumor progression was demonstrated in seven of the eight patients after treatment.

CONCLUSION

Tumoricidal concentrations of the immunotoxin 454A12-rRA can be attained safely in the CSF of patients with leptomeningeal tumor spread.

Patient retention in mobile and fixed-site methadone maintenance treatment

The retention of patients (n = 399) enrolled in mobile health services (MHS), a Baltimore outpatient mobile methadone treatment program, was compared to patient retention (n = 1588) in six Baltimore fixed-site programs. Mobile program patients were retained for a median of 15.53 months in treatment in comparison to 3.90 for fixed-site patients (n = 664) from the MHS served zip codes (MHSZIPS) and 6.27 for fixed-site patients (n = 924) from zip codes other than those served by MHS (OTHERZIPS), (P < 0.001). Using Cox regression, the characteristics of patients associated with earlier discharge were (1) higher number of arrests, (2) more frequent cocaine use and (3) lower family income. These predictors of shorter retention were generally more prevalent among patients from the MHS served zip codes. Therefore, the longer retention in treatment of MHS patients as compared to OTHERZIPS fixed-site program patients is even more striking. Consistent with these differences in retention, were finding in a prior study suggesting that the mobile program provided greater access to services in reducing patient transportation cost and travel time. Thus, mobile methadone maintenance treatment appears to be a useful means of providing services.

Reactivity of murine cytokine fusion toxin, diphtheria toxin390-murine interleukin-3 (DT390-mIL-3), with bone marrow progenitor cells

Myeloid leukemias can express interleukin-3 receptors (IL-3R). Therefore, as an antileukemia drug, a fusion immunotoxin was synthesized consisting of the murine IL-3 (mIL-3) gene spliced to a truncated form of the diphtheria toxin (DT390) gene coding for a molecule that retained full enzymatic activity, but excluded the native binding domain. The DT390-mIL-3 hybrid gene was cloned into a vector under the control of an inducible promote. The fusion protein was expressed in Escherichia coli and then purified from inclusion bodies. The fusion toxin was potent because it inhibited FDC-P1, an IL-3R-expressing murine myelomonocytic tumor line (IC50 = 0.025 nmol/L or 1.5 ng/mL). Kinetics were rapid and cell-free studies showed that DT390-mIL-3 was as toxic as native DT. DT390-mIL-3 was selective because anti-mIL-3 monoclonal antibody, but not irrelevant antibody, inhibited its ability to kill. Cell lines not expressing IL-3R were not inhibited by the fusion protein. Because the use of DT390-mIL-3 as an antileukemia agent could be restricted by its reactivity with committed and/or primitive progenitor cells, bone marrow (BM) progenitor assays were performed. DT390-mIL-3 selectively inhibited committed BM progenitor cells as measured by in vitro colony-forming unit-granulocyte-macrophage and in vivo colony-forming unit-spleen colony assays. To determine if this fusion protein was reactive against BM progenitor cells required to rescue lethally irradiated recipients, adoptive transfer experiments were performed. Eight million DT390-mIL-3-treated C57BL/6 Ly5.2 BM cells, but not 4 million, were able to rescue lethally irradiated congenic C57BL/6 Ly5.1 recipients, suggesting that progenitor cells might be heterogenous in their expression of IL-3R. This idea was supported in competitive repopulation experiments in which DT390-mIL-3 treated C57BL/6 Ly5.2 BM cells were mixed with nontreated C57BL/6 Ly5.1 BM cells and used to reconstitute C57BL/6 Ly5.1 mice. A significant reduction, but not elimination, of Ly5.2-expressing cells 95 days post-BM transplantation and secondary transfer experiments indicated that IL-3R is not uniformly expressed on all primitive progenitor cells. The fact that some early progenitor cells survived DT390-mIL-3 treatment indicates that this fusion toxin may be useful in the treatment of myeloid leukemias that express the IL-3R.

Frozen section consultation. Utilization patterns and knowledge base of surgical faculty at a university hospital

The authors studied the knowledge base of surgical faculty concerning frozen section consultations at a university hospital to determine whether it had any relationship to the appropriateness of frozen section requests. To accomplish this, the reasons for performing frozen sections during a 3-month period were analyzed, and those request that seemed ambiguous or inappropriate were identified. Simultaneously a 15-item questionnaire was distributed to faculty and housestaff dealing with factual information concerning the technique and limitations of frozen section diagnosis (Questions 1-8), as well as appropriateness of frozen section requests in a number of clinical situations (Questions 9-15). The collective score on items of general information (Questions 1-8) was 69%, whereas scores on Questions 9-15 ranged from 39% on the gynecologic question related to evaluation of a cystic ovarian mass to 81% on the general surgery question regarding evaluation of a soft tissue mass. Of 914 frozen sections, 95% were performed for appropriate reasons, which included evaluation of margins (46%), establishing a primary diagnosis (43%), determining adequacy or viability of tissue (3%), or satisfying immediate patient/family concerns ( < 1%). Five percent of frozen sections were performed for ambiguous or seemingly inappropriate reasons. Because fewer than five faculty members were responsible for the inappropriate frozen section request, the authors did not find that the results of the questionnaire predicted or anticipated situations in which inappropriate requests occurred. Nonetheless, the results of the questionnaire indicate there is important general information concerning frozen sections that is not uniformly shared by surgical faculty, such as the types of tissue that cannot be cut on a cryostat, the reasons for deferred frozen sections, and the situations in which fresh tissue is needed for special studies. The authors suggest the inappropriate frozen section could be diminished by an educational initiative targeted at a relatively small segment of clinical faculty, whereas enhancement of general information regarding frozen section should ideally occur in the broader context of clinical conferences using illustrative case material.

Validity of intravenous drug abusers' self-reported changes in HIV high-risk drug use behaviors

The HIV-1 high-risk drug use behavior of intravenous drug abusers was assessed both retrospectively (for 6 months) and prospectively (for 6 months) via structured interview and urinalysis testing. Subjects were 281 intravenous drug abusers, 146 enrolled in outpatient methadone treatment (Treatment group) and 135 not in treatment (Community group). The Treatment group reported fewer drug injections and less needle sharing and had fewer positive urinalyses for opiates and cocaine than did the Community group. Reported drug injection and needle sharing declined over time, and an increasing proportion of subjects reported abstinence from these behaviors. In contrast to the behavioral reports of subjects, positive urinalyses indicating opiate and/or cocaine use did not decline over time. Almost half (45.8%) of the reported increase in injection abstinence from intake to month six was disconfirmed by urinalysis. In contrast to this large discrepancy regarding reported behavior change, there was good agreement between reported injection abstinence and urinalysis results at single points in time. These data indicate that the validity of the reported HIV-1 risk behavior change of drug abusers may be less than that of reported risk behavior occurrence. The data raise important questions about the validity of reported reductions in high-risk drug use behaviors, and indicate the importance of using biological indicators of HIV-1 risk behavior (such as urinalysis) whenever possible.

Rapid and simple PCR assay for quantitation of human immunodeficiency virus type 1 RNA in plasma: application to acute retroviral infection

A method for quantitating human immunodeficiency virus type 1 plasma viremia may be useful in monitoring disease progression and the responsiveness of patients to a therapeutic regimen or vaccine. A quantitative assay for viral RNA in plasma or sera that differs in several aspects from those reported previously was developed. First, whereas conventional reverse transcriptase-PCR assays involve a two-step process and use two enzymes, the method described uses a single enzyme, rTth DNA polymerase, for both reverse transcription and PCR. The reactions are carried out in a single tube and with a single buffer solution with uninterrupted thermal cycling. Second, uracil-N-glycosylase and dUTP are incorporated into the reaction mixtures to ensure that any carryover of DNA from previous amplifications will not compromise quantitation. Third, a quantitation standard is incorporated into each reaction mixture so that differences in amplification efficiency caused by sample interferents, variability in reaction conditions, or thermal cycling can be normalized. To ensure comparable amplification efficiency, the quantitation standard has the same primer-binding regions as the human immunodeficiency virus type 1 target and generates an amplified product of the same size and base composition. The probe-binding region was replaced with a sequence that can be detected separately. Fourth, a colorimetric detection format was modified to provide at least a four-log-unit dynamic range. The quantitative assay requires only a single amplification of the sample and can be completed in less than 8 h. The procedure was used on archival samples to demonstrate the viremic spike in acute infection and the suppressed levels of circulating virus following seroconversion.

Pharmacokinetics and toxicology of immunotoxins administered into the subarachnoid space in nonhuman primates and rodents

Immunotoxins have been suggested as possible therapeutic agents in patients with leptomeningeal carcinomatosis. The pharmacokinetics, stability, and toxicity of immunotoxins injected into the i.t. space were examined in rats and rhesus monkeys. Monoclonal antibodies specific for the human (454A12 and J1) and rat (OX26) transferrin receptors were coupled to recombinant ricin A chain. In monkeys, the maximally tolerated dose of the anti-human transferrin receptor immunotoxin (454A12-rRA) was a dose that yielded a nominal cerebrospinal fluid (CSF) concentration of approximately 1.2 x 10(-7) M. In rats, the 10% lethal dose (LD10) of the anti-human transferrin receptor immunotoxin was a dose yielding a nominal CSF concentration of 8.8 x 10(-7) M whereas the LD10 of the anti-rat transferrin receptor immunotoxin (OX26-rRA) was a dose yielding a nominal CSF concentration of 1.2 x 10(-7) M. Thus, the species-relevant antibody resulted in toxicity at a concentration one-seventh that of the immunotoxin with the irrelevant antibody. A comparison of the area under the concentration curve at the LD10 for rats with the area under the concentration curve at the maximally tolerated dose in monkeys and humans shows that the species-relevant immunotoxin was a better predictor of the toxic dose of the anti-transferrin receptor immunotoxin in humans than the irrelevant immunotoxin. The pharmacokinetics of the 454A12-rRA immunotoxin within the CSF of monkeys showed a biphasic clearance with an early-phase half-life of 1.4 h and a late phase half-life of 10.9 h. The clearance was 4.4 ml/h or approximately twice the estimated clearance due to bulk flow of CSF. Loss by degradation was ruled out because immunoblot analysis showed that the immunotoxin was stable for up to 24 h after administration. Possible losses in addition to sampling include diffusion into brain tissue and transcapillary permeation. The apparent volume of distribution was 10.1 ml or approximately three-fourths the total CSF volume of the monkey. Dose limiting toxicity corresponded with the selective elimination of Purkinje cells in both rats and monkeys and was manifested clinically as ataxia and lack of coordination. The onset of ataxia in monkeys occurred within 5 days and, in the more mild form, was reversible with time. There was evidence of only minimal inflammation within the CSF, and there were no signs of systemic toxicity. Immunotoxins injected into the subarachnoid space may have potential for treatment of leptomeningeal carcinomatosis.

Antisocial personality disorder and HIV infection among intravenous drug abusers

OBJECTIVE

Antisocial personality disorder in drug abusers has been associated with poor treatment outcome. The authors examined the relationship between diagnosis of antisocial personality and HIV infection.

METHOD

Subjects were 272 intravenous drug abusers, 140 (52%) of whom were in methadone treatment. Subjects were given an HIV risk behavior interview before diagnostic interviewing and HIV testing.

RESULTS

Using the DSM-III-R definition, the authors found that 119 (44%) of the subjects met criteria for antisocial personality. Significantly more of the subjects with antisocial personality (18% [N = 21] than of the subjects without antisocial personality (8% [N = 12]) had HIV infection. The diagnosis of antisocial personality disorder was associated with a significantly higher odds ratio of infection independent of ethnicity, gender, and treatment status.

CONCLUSIONS

Antisocial personality is a risk factor for HIV infection among intravenous drug abusers.

Thiol-containing cross-linking agent with enhanced steric hindrance

Ricin A chain immunotoxins disulfide cross-linked with conventional, sterically unhindered reagents have unsatisfactorily short circulating life times in vivo. (Acetylthio)succinic anhydride, a thiolating reagent with partial steric hindrance of the sulfur atom, does not remedy this situation. Sulfosuccinimidyl N-[3-(acetylthio)-3-methylbutyryl]-beta- alaninate, a new cross-linker in which the carbon alpha to the sulfur is doubly methylated, creates disulfide bonds 2 orders of magnitude more resistant to reduction than unhindered disulfides. Nevertheless, this deactivated thiolating agent rapidly and reliably cross-links ricin A chain and antibodies to create immunotoxins with in vitro cytotoxicities comparable to those of 2-iminothiolane-coupled conjugates.

MRI and diabetic foot infections

The role of magnetic resonance imaging and plain radiographs in evaluating osteomyelitis in the diabetic foot was studied. Fifty patients were prospectively examined by magnetic resonance imaging and plain radiographs to determine the extent of infection. Thirty-seven patients had positive MRI for osteomyelitis and 19 were positive with conventional radiography. Thirteen patients had negative MRI healed with short course of antibiotics. Five patients with positive MRI received four weeks' course of intravenous antibiotics with two still having persistent infection in the six weeks follow-up. Thirty-two patients underwent surgery with favorable results. Sixty-two bone specimens were obtained for histologic evaluation of osteomyelitis. In cases with histologic proof of diagnosis, magnetic resonance sensitivity was 99%, specificity was 81%, and accuracy was 94%. Thus magnetic resonance imaging was shown to have a high sensitivity, specificity, and accuracy in detecting osteomyelitis.

Improved tumor-specific immunotoxins in the treatment of CNS and leptomeningeal neoplasia

A novel antibody-toxin conjugate has been developed for use in cancer therapy. This report demonstrates that this new reagent selectively kills glioblastoma- and medulloblastoma-derived cell lines, medulloblastoma cells in primary culture, and cell lines derived from tumors commonly metastatic to the cerebrospinal fluid (CSF). Efficient killing of human tumor cells occurred at concentrations between 3.9 X 10(-13) M and 1.1 X 10(-10) M, whereas guinea pigs and rhesus monkeys tolerated intrathecal levels of 2 X 10(-9) M. Cerebrospinal fluid from normal humans and from brain-tumor patients does not inhibit the in vitro efficacy of this reagent. The wide therapeutic window, extreme potency, and general applicability of this antibody-toxin conjugate against CSF-borne primary or metastatic tumors warrants clinical trials.

A preliminary pharmacokinetic study of 111In-labeled 260F9 anti-(breast cancer) antibody in patients

The pharmacokinetics of 111In-labeled 260F9, a murine monoclonal antibody directed against a breast-cancer-associated antigen, was determined in seven patients with advanced breast cancer. Six patients were administered 1 mg antibody containing 1 mCi 111In. The seventh patient was administered 20 mg unlabeled antibody followed by 1 mg 111In-labeled antibody all via a peripheral vein. Immunoprecipitation, HPLC and SDS-PAGE gels demonstrated the stability of radiolabel on the antibody. The serum clearance of the radiolabel closely fits (r2 greater than 0.95) a two-compartment model for the first six patients. The apparent volume of distribution of the radiolabel approximated to the plasma volume (31) and its mean residence time was 23.7 h. The radiolabel had an average t 1/2 beta of 22.9 +/- 12.21 h at the 1-mg dose. At the 20-mg dose one-compartment elimination kinetics were observed with the radiolabel and antibody showing similar mean residence times (36-41 h) and a t 1/2 beta of 26-28 h. Whole-body imaging showed that the blood-pool: liver ratio of radioactivity increased fourfold (at 48 h postinfusion) at the higher dose and the percentage of the injected dose of radioactivity in the liver decreased from 25% to 8% (24 h postinfusion). In one patient 7-14 times more radioactivity was localized in a breast tumor than in fat (normal breast). Over the first 25 h an average (cumulative) 7.5% of the total dose was excreted in urine. A study of 260F9 in CDF-1 mice demonstrated that the radiolabel remained associated with the antibody in serum. The antibody, however, cleared 60-fold slower in mice than in patients and showed an increased mean residence time of 191 h. The disparity in the pharmacokinetics of the antibody seen in the mouse and in the clinic, points to the different behavior shown by murine monoclonal antibodies in humans. This points to the need for preliminary studies of antibodies in patients for preclinical evaluations of their effectiveness as drug-targeting agents.

The role of the diphtheria toxin receptor in cytosol translocation

The role of the receptor in the transport of diphtheria toxin (DT) to the cytosol was examined. A point-mutant form of DT, CRM 107 (CRM represents cross-reacting material), that has an 8,000-fold lower affinity for the DT receptor than native toxin was conjugated to transferrin and monoclonal antibodies specific for the cell-surface receptors T3 and Thy1. Conjugating the binding site-inactivated CRM 107 to new binding moieties reconstituted full toxicity, indistinguishable from native DT linked to the same ligand, indicating that the entry activity of the DT B chain can be fully separated from the receptor binding function. Like DT, the toxin conjugates exhibited a dose-dependent lag period before first-order inactivation of protein synthesis. Inactivation of the binding site of the toxin portion of the conjugate was found to have no effect on the kinetics of protein synthesis inactivation. The receptor used by the toxin determined the length of the lag period relative to the killing rate. Comparing the potency of CRM 107 conjugates with native DT, standardized for receptor occupancy, shows that new receptors can be as or more efficient than the DT receptor in transporting DT to the cytosol. The transferrin-CRM 107 conjugate, unlike native DT, was highly toxic to murine cells. All the data presented are consistent with a model that the DT receptor, other than initiating rapid internalization of the toxin to low pH compartments, is unnecessary for transport of the toxin to the cytosol and that membrane translocation activity is expressed by the DT B subunit independent of the receptor-binding site.

Mutations in diphtheria toxin separate binding from entry and amplify immunotoxin selectivity

Monoclonal antibodies linked to toxic proteins (immunotoxins) can selectively kill some tumor cells in vitro and in vivo. However, reagents that combine the full potency of the native toxins with the high degree of cell type selectivity of monoclonal antibodies have not previously been designed. Two heretofore inseparable activities on one polypeptide chain of diphtheria toxin and ricin account for the failure to construct optimal reagents. The B chains (i) facilitate entry of the A chain to the cytosol, which allows immunotoxins to efficiently kill target cells, and (ii) bind to receptors present on most cells, which imparts to immunotoxins a large degree of non-target cell toxicity. This report identifies point mutations in the B polypeptide chain of diphtheria toxin that block binding but allow cytosol entry. Three mutants of diphtheria toxin have 1/1,000 to 1/10,000 the toxicity and 1/100 to 1/8,000 the binding activity of diphtheria toxin. Linking of either of two of the inactivated mutant toxins (CRM103, Phe508; CRM107, Phe390, Phe525) to a monoclonal antibody specific for human T cells reconstitutes full target-cell toxicity--indistinguishable from that of the native toxin linked to the same antibody--without restoring non-target cell toxicity. This separation of the entry function from the binding function generates a uniquely potent and cell type-specific immunotoxin that retains full diphtheria toxin toxicity, yet is four to five orders of magnitude less toxic than the native toxin is to nontarget cells.

Functional expression of the human transferrin receptor cDNA in Chinese hamster ovary cells deficient in endogenous transferrin receptor

Transferrin (Tf) receptor-variant Chinese hamster ovary cells have been isolated by selection for resistance to two Tf-toxin conjugates. The hybrid toxins contain Tf covalently linked to ricin A chain or a genetically engineered diphtheria toxin fragment. The Tf-receptor-variant (TRV) cells do not have detectable cell-surface Tf receptor; they do not bind fluorescein-Tf or 125I-Tf. TRV cells are at least 100-fold more resistant to the Tf-diphtheria toxin conjugate than are the parent cells. The TRV cells have retained sensitivity to native diphtheria toxin, indicating that the increased resistance to the conjugate is correlated with the loss of Tf binding. The endocytosis of fluorescein-labeled alpha 2-macroglobulin is normal in TRV cells, demonstrating that the defect does not pleiotropically affect endocytosis. Since these cells lack endogenous Tf receptor activity, they are ideally suited for studies of the functional expression of normal or altered Tf receptors introduced into the cells by cDNA transfection. One advantage of this system is that Tf binding and uptake can be used to monitor the behavior of the transfected receptor. A cDNA clone of the human Tf receptor has been transfected into TRV cells. In the stably expressing transfectants, the behavior of the human receptor is very similar to that of the endogenous Chinese hamster ovary cell Tf receptor. Tf binds to cell surface receptors, and is internalized into the para-Golgi region of the cell. Iron is released from Tf, and the apo-Tf and its receptor are recycled back to the cell surface. Thus, the TRV cells can be used to study the behavior of genetically altered Tf receptors in the absence of interfering effects from endogenous receptors.

Use of the Greenfield filter for thromboembolic disease in pregnancy

Recent technical advances in surgical intervention for thromboembolic disease have made the Greenfield filter a safe and effective treatment when heparin is contraindicated or recurrent emboli develop. One successful use of Greenfield filter placement in pregnancy has been reported. We report six additional cases. Maternal morbidity was negligible, and fetal outcomes were good. The use of the Greenfield filter as an adjunctive therapy for treatment of severe thromboembolic disease in pregnancy appears to be safe and should be considered in appropriate candidates.

Cloned fragment of diphtheria toxin linked to T cell-specific antibody identifies regions of B chain active in cell entry

The role of discrete domains of diphtheria toxin (DT) B chain in cytosol entry and cytotoxicity was investigated by linking a monoclonal antibody recognizing the human T cell-specific antigen T3 (UCHT1) to diphtheria toxin (UCHT1-DT), DT A subunit (UCHT1-DTA), or to a genetically engineered form of DT (UCHT1-MspSA) lacking the C-terminal 17-kDa portion of the B subunit. The N-terminal 21-kDa region of DT B chain increased toxicity of UCHT1-DTA 100-fold (UCHT1-MspSA) while addition of the C-terminal 17-kDa region (UCHT1-DT) increased toxicity 100-fold more. The cytotoxicity was dependent upon antibody binding as demonstrated by blocking toxicity with excess UCHT1. The differences in toxicity between these reagents were not due to differences in ADP-ribosylation activity of DT A chain, binding activity of the antibody moiety, extent of DT nicking, or the cross-linking method, so we conclude that the large differences in toxicity were due to the presence of different B chain domains. The large increase in toxicity by the C-terminal region of DT B did not appear to be caused by DT receptor binding. The lysosomotropic agent NH4Cl blocked the cytotoxic effect of DT, UCHT1-DT, and UCHT1-MspSA but not UCHT1-DTA.

Nucleotide sequence of the structural gene for diphtheria toxin carried by corynebacteriophage beta

A 1,942-base-pair DNA segment encoding the structural gene for diphtheria toxin was sequenced, and the primary structure of the toxin was deduced. Restriction enzyme fragments corresponding to nontoxic or hypotoxic peptides of the toxin were isolated from corynebacteriophage beta and cloned into Escherichia coli on plasmid pBR322, and the sequence was determined. The mature toxin molecule deduced from the sequence has 535 amino acid residues and a molecular weight of 58,342. The deduced sequence for the fragment A moiety was the same as that determined at the protein level, except for a single serine residue, which had been mispositioned in the earlier study. Several differences were noted with respect to the partial sequence data available on the fragment B moiety, some or all of which may reflect genetic variations among populations of corynephages carrying the toxin gene. The DNA sequence predicts a 25-residue leader peptide preceding the mature protein, which is presumably involved in secretion of the toxin from lysogenized Corynebacterium diphtheriae. We infer that initiation of translation probably occurs at a GTG codon (codon -25). Cloned restriction fragments containing sequences for the amino-terminal region of toxin, together with 5' flanking regions, were expressed in E. coli. Toxin-related peptides were synthesized and secreted into the periplasmic space. These results provide a basis for applying recombinant DNA methods to the study of diphtheria toxin and for producing novel, genetically altered forms of the toxin suited to the construction of new classes of immunotoxins.

The araC regulatory gene mRNA contains a leader sequence

An estimation of the size of the araC gene in Escherichila coli B/r was made by sub-cloning restriction fragments of the araC-containing hybrid plasmid pTB1 into the plasmid pBR322. Plasmids which contained a functional araC gene were identified by genetic complementation tests. DNA sequence analysis of the promoter-proximal region of the araC gene revealed that araC mRNA contains a 150 nucleotide leader.

DNA sequence of the araBAD promoter in Escherichia coli B/r

The L-arabinose operon in Escherichia coli is a model system for the study of the control of gene expression. Maximal expression of the araBAD operon requires two positive control components: the araC protein-L-arabinose complex and the cyclic AMP receptor protein-cyclic AMP complex. Both araC protein and cyclic AMP receptor protein are required for the initiation of transcription of araBAD mRNA. We have used the plasmid pBR322 as a vector for cloning DNA fragments that contain the araBAD promoter. The cloned ara fragments were identified by both physical and genetic tests. A restriction map was constructed and the DNA sequence of the promoter was determined. The promoter contains a site that is similar to the RNA polymerase recognition sites in the galactose and lactose operons. It also contains a region similar to the known cyclic AMP receptor protein binding sites in the galactose and lactose operons.

Hybrid plasmids containing the araBAD genes of Escherichia coli B/r

The DNA fragments generated by restriction endonuclease BamI which contain the araCBAD genes from E.coli B/r have been cloned. The DNA fragments containing ara genes were idenified by a compairson of the BamI fragments of lambdah80dara phages containing different ara deletion mutations. The ara genes were cloned into the plasmid pBR317, a derivative of ColE1. The cloned DNA fragments were analyzed by digestion with pairs of restriction endonucleases to determine the molecular weight of the chimeras and to identify the cloned ara DNA fragments. The cloned ara fragments were also identified by genetic complementation and recombination tests.

111Indium-bleomycin breast and axilla imaging

111Indium-Bleomycin (111In-Blm), a new radiopharmaceutical, was administered intravenously to 37 patients with benign and malignant breast lesions. Early and delayed images of both the breasts and axillae were made, and results were correlated with physical examination, histopathology of the excised lesion, mammography, and thermography. In 18 patients with malignant disease, clinical examination of the breast and axilla correlated with histopathology in 78 and 54% of the cases, respectively. Images of the breast were accurate (true positives) in 83% of the cases. Images of the axilla were accurate in 62% of the cases. Mammography was correct and suggested malignancy in 88%, and thermography in 73% of the cases. In 19 patients with benign breast lesions, clinical examination of the breast and axilla correlated with histopathology in 68 and 95% of the cases, respectively. Scans of the breast and axilla were correct (true negative) 79 and 95% of the time, respectively. Mammography was correct, and suggested benignancy, in 53% and thermography in 25% of the cases. Imaging of the breasts using 111In-Blm appears to be as accurate as physical examination and mammography for palpable benign and malignant breast tumors. It is less accurate than mammography for microscopic malignancies. Axillary imaging does not appear to be worthwhile because many axillary metastases are too small for detection with current nuclear medicine instrumentation.

Unit doses

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