Tumor-inhibitory antibiotic uptake facilitated by leukoregulin: a new approach to drug delivery.

The uptake of tumor-inhibitory antibiotics by human K562 erythroleukemia cells was examined in the presence of leukoregulin to determine if the lymphokine's ability to increase the plasma membrane permeability of tumor cells facilitates concurrent entry of pharmacologically active molecules. K562 cells were exposed to 0.25-2.0 micrograms of doxorubicin/mL for up to 60 minutes at 37 degrees C. Commencing within 15 minutes, leukoregulin increased the entry of doxorubicin approximately twofold and the uptake of mitomycin, mithramycin, and propidium iodide twofold to tenfold. This finding indicates the potential biotherapeutic value of leukoregulin in promoting the selective entry of pharmacologically active molecules into leukoregulin-sensitive target cells.

Decreased P-glycoprotein expression in multidrug-sensitive and -resistant human myeloma cells induced by the cytokine leukoregulin.

Modulation of the expression of P-glycoprotein, a plasma membrane protein associated with multidrug resistance, was examined in drug-sensitive and drug-resistant tumor cells treated with leukoregulin, a M(r) 50,000 cytokine from human lymphocytes that rapidly permeabilizes the plasma membrane of many tumor cells facilitating the uptake of doxorubicin and other tumor-inhibitory antibiotics. P-glycoprotein expression was measured flow cytometrically by the binding of C219 or MRK16 monoclonal antibody to multidrug-sensitive human K562 erythroleukemia and 8226/S myeloma cells, compared to multidrug-resistant 8226/DOX40 myeloma cells. Cells were treated for up to 2 h with up to 80 units of leukoregulin/ml or one of a variety of unrelated cytokines including interleukin 1 alpha (IL-1 alpha), IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, colony-stimulating factor, macrophage colony-stimulating factor, granulocyte macrophage colony-stimulating factor, tumor necrosis factor alpha, gamma-interferon, alpha-interferon, epidermal growth factor, platelet-derived growth factor AA, platelet-derived growth factor BB, insulin-like growth factor I, insulin-like growth factor II, fibroblast growth factor, or transforming growth factor beta. Leukoregulin caused a concentration-dependent decrease in P-glycoprotein expression; however, P-glycoprotein expression was unaffected by the other cytokines (< 12% decrease in expression). Leukoregulin-induced membrane permeabilization, determined flow cytometrically by intracellular fluorescein efflux, and decreased P-glycoprotein expression occurred simultaneously within 15 min in drug-sensitive and -resistant cells. Enhanced doxorubicin uptake, measured flow cytometrically by doxorubicin influx, was also present within 15 min. Leukoregulin enhancement of doxorubicin uptake and increased membrane permeability varied directly with the decrease in P-glycoprotein expression. Leukoregulin in combination with doxorubicin enhanced the inhibition of cell proliferation in 8226/DOX40 multidrug-resistant cells over expressing P-glycoprotein. In contrast, combined treatment of HL-60/MX2 multidrug-resistant human promyelocytic leukemia cells that do not overexpress P-glycoprotein in association with their multidrug resistance resulted in no greater growth inhibition than observed with HL-60/MX2 cells treated with doxorubicin alone. This is the first demonstration that a naturally occurring macromolecule with anticancer activities can modulate the expression of P-glycoprotein concomitant with enhanced drug uptake and inhibition of cell proliferation.

Urinary catheters: what type do men and their nurses prefer?

OBJECTIVES: Urinary catheters are used frequently, but the relative risks and benefits of different types of devices are not clear. We sought to determine the beliefs of both older male patients and nursing staff about the relative merits and problems of condom and indwelling catheters. DESIGN: Patient and nurse survey using convenience sampling. SETTING: A University-affiliated Veterans Affairs medical center. PARTICIPANTS: Men hospitalized on medical, rehabilitation and nursing home units using either an indwelling or a condom catheter were invited to participate as were all members of the nursing staff on these units. Of 116 eligible patients, 104 were interviewed (response rate = 90%). Of 107 eligible nursing staff members, 99 completed the questionnaires (response rate = 92%). INTERVENTION AND MEASUREMENTS: Consenting patients were interviewed personally about their urinary catheter. The nursing staff were asked to complete a self-administered questionnaire. RESULTS: Patients were mostly older and predominantly hospitalized on the medical service. Compared with those using an indwelling catheter, patients using a condom catheter were more likely to believe that their catheter was comfortable (86 vs 58%, P = .04) and less likely to believe it was painful (14 vs 48%, P = .008) or to restrict their activity (24 vs 61%, P = .002). The nursing staff had a mean of 13 years nursing experience, and the majority worked in the nursing home unit. Most of the nursing staff respondents believed that condom catheters were less painful and restrictive for patients and were easier to apply, but they also believed that they fell off and leaked more often and required more nursing time. CONCLUSIONS: Both patients and nursing staff prefer condom to indwelling catheters for patient comfort, but they recognize that dislodgment and leaking are major drawbacks of condom catheters. A more secure condom catheter would greatly improve the management of male incontinence.

Theoretical analysis of non-invasive oscillometric maximum amplitude algorithm for estimating mean blood pressure.

A theoretical analysis is performed to evaluate the effect of arterial mechanical and blood pressure pulse properties on the accuracy of non-invasive oscillometric maximum amplitude algorithm (MAA) estimates of the mean blood pressure obtained using air-filled occlusive cuffs. Invasively recorded blood pressure pulses, selected for their varied shapes, are scaled to simulate a wide range of blood pulse pressures (diastolic blood pressure minus systolic blood pressure). Each scaled blood pressure pulse is transformed through an exponential model of an artery to create a series of blood volume pulses from which a simulated oscillometric waveform is created and the corresponding MAA estimate of the mean blood pressure and error (mean blood pressure minus MAA estimate) are determined. The MAA estimates are found to depend on the arterial blood pressure. The errors are found to depend on the arterial mechanical properties, blood pressure pulse shape and blood pulse pressure. These results suggest that there is no direct relationship between the mean blood pressure and MAA estimate, and that multiple variables may affect the accuracy of MAA estimates of the mean blood pressure obtained using air-filled occlusive cuffs.

Upper limb disorders.

Disorders of the upper limb cause significant morbidity and incur substantial costs. These conditions are amongst the most common reasons for attendance to occupational physicians, and they are also commonly encountered in the practice of a wide array of medical specialities (rheumatology, orthopaedic surgery, rehabilitation and neurology). Despite this collective experience, standardized methods for labelling these conditions and algorithms for their clinical evaluation and treatment are only beginning to be developed. The purpose of this review is to outline a classification system for upper limb disorders, to address the features of the clinical history and examination which are of most benefit in reaching a diagnosis, and to briefly outline approaches to investigation and treatment.

Diabetic bullae: 12 cases of a purportedly rare cutaneous disorder.

BACKGROUND: Spontaneous bullae are a characteristic type of skin lesion occurring in patients with diabetes mellitus. These diabetic bullae are considered to be a rare phenomenon; only about 100 cases have been described in the literature since the disorder was first reported 70 years ago. METHODS: We collected a series of patients with diabetic bullae who were referred to us at a Veterans Affairs Medical Center Clinic specializing in diabetic foot problems. We then reviewed the medical literature for similar cases and summarized the available information. RESULTS: We saw 12 patients with typical diabetic bullae over an 8-year period in our clinic. The clinical presentation and outcome of the lesions in these patients were similar to those in previously reported cases. The patients were mostly elderly, all but one had lesions located on the lower extremities, all had peripheral neuropathy, two had secondary staphylococcal infection of their bullae, and in all patients the lesions healed without scarring. Although most of the patients had had previous similar lesions, the diagnosis of diabetic bullae had not been previously reported in any of them. CONCLUSIONS: We have reviewed the clinical syndrome of diabetic bullae and presented brief clinical details of these cases; we offer several vignettes and photographs of these lesions to remind clinicians of what we believe is a not so rare cutaneous disorder.

Influence of endogenous Thy1.1 cells upon the efficacy of an anti-Thy1.1 antibody-diphtheria toxin conjugate.

The chemical conjugation of antibodies to protein toxins results in cell-specific cytotoxic agents that can be defined in terms of in vitro potency and efficacy; however, it is the in vivo utilities that are largely being pursued in clinical trials. The nature of in vivo target cell depletion by toxin conjugates is largely unknown. The anti-murine Thy1.1 antibody-diphtheria toxin conjugate possesses high in vitro efficacy, and because mice are remarkably resistant to the native toxin, the conjugate possesses in vivo efficacy. When administered intravenously, the conjugate is shown to deplete peripheral blood Thy1.1+ target cells in a concentration-dependent fashion. When the log kill of Thy1.1+ tumor cells was analyzed by the life span extension method, it was determined, however, that the log kill is inversely proportional to the number of target cells. That is, the presence of an endogenous cell population, which is expressing the same surface antigen targeted by the antibody conjugate as on the pathological cell, may drastically lower the clinical efficacy of the immunotoxin. Thus, the greatest potential for antibody-toxin conjugates will be for low target cell burdens and for pathogenic cell populations expressing unique surface antigens. These are important considerations in the design of bioconjugates to insure high in vivo efficacy in elimination of intended target cells.

Antibiotic therapy for diabetic foot infections: comparison of two parenteral-to-oral regimens.

This prospective, randomized, multicenter trial compared the efficacy of two antibiotic regimens for treatment of foot infections in diabetic adults. Patients with infections requiring hospitalization were randomized to receive either intravenous ofloxacin followed by oral ofloxacin or intravenous ampicillin/sulbactam followed by oral amoxicillin/clavulanate (the aminopenicillin regimen) for 14-28 days. Patients with osteomyelitis were eligible for the study if the infected bone was to be removed. Of 108 patients enrolled in the study, 88 who were evaluable had various skin and soft-tissue infections, and 24% had osteomyelitis. For the ofloxacin and aminopenicillin regimens, the mean duration of intravenous therapy was 7.8 and 7.1 days, respectively, the mean duration of oral therapy was 13.2 and 12.0 days, respectively, the rate of eradication of pathogens was 78% and 88%, respectively, and the overall rate of clinical cure or improvement was 85% and 83%, respectively. Thus, about 3 weeks of therapy with either regimen was well tolerated and effective in treating these diabetic foot infections.

Molecular characterization of the toxic cyanobacterium Cylindrospermopsis raciborskii and design of a species-specific PCR.

Cylindrospermopsis raciborskii is a toxic-bloom-forming cyanobacterium that is commonly found in tropical to subtropical climatic regions worldwide, but it is also recognized as a common component of cyanobacterial communities in temperate climates. Genetic profiles of C. raciborskii were examined in 19 cultured isolates originating from geographically diverse regions of Australia and represented by two distinct morphotypes. A 609-bp region of rpoC1, a DNA-dependent RNA polymerase gene, was amplified by PCR from these isolates with cyanobacterium-specific primers. Sequence analysis revealed that all isolates belonged to the same species, including morphotypes with straight or coiled trichomes. Additional rpoC1 gene sequences obtained for a range of cyanobacteria highlighted clustering of C. raciborskii with other heterocyst-producing cyanobacteria (orders Nostocales and Stigonematales). In contrast, randomly amplified polymorphic DNA and short tandemly repeated repetitive sequence profiles revealed a greater level of genetic heterogeneity among C. raciborskii isolates than did rpoC1 gene analysis, and unique band profiles were also found among each of the cyanobacterial genera examined. A PCR test targeting a region of the rpoC1 gene unique to C. raciborskii was developed for the specific identification of C. raciborskii from both purified genomic DNA and environmental samples. The PCR was evaluated with a number of cyanobacterial isolates, but a PCR-positive result was only achieved with C. raciborskii. This method provides an accurate alternative to traditional morphological identification of C. raciborskii.

Radioreceptor assays for sensitive detection and quantitation of saxitoxin and its analogues from strains of the freshwater cyanobacterium, Anabaena circinalis.

Toxic freshwater cyanobacteria can contaminate water supplies and adversely effect humans, agricultural livestock, and wildlife. Toxicity is strain-specific so morphological observations alone cannot predict the hazard level. Two microtiter plate based bioassays have emerged for measuring saxitoxin (STX) and its derivatives, commonly found in the freshwater cyanobacteria Anabaena and Aphanizomenon. They use radioactively labeled STX binding by sodium channels, STX's pharmacological target, or an unrelated protein, saxiphilin. These bioassays were challenged with extracts of toxic and nontoxic strains of Anabaena circinalis, and the results were compared with HPLC analysis. Both radioreceptor assays had detection limits of 2 microg STX equivalents (STXeq)/L, which is belowthe concentration proposed for a health alert, namely 3 microg STXeq/L. In all cases, statistically significant correlations existed between all toxicity measurements of the same extracts with the methods used herein. Sodium channel and saxiphilin assays however predicted less toxicity relative to HPLC analysis. The only exception to this was the equivalency observed between saxiphilin measurement and HPLC quantitation corrected for mammalian toxicity. Saxiphilin assay predicted toxicity in one strain was 3 orders of magnitude more than by sodium channel assay, and no STX was detected by HPLC. Lack of acetylcholinesterase inhibition showed this bioactivity was not anatoxin-a(S), a toxin also produced by this A. circinalis with some resemblance to the region of STX bound by saxiphilin. Presence of anatoxin-a(S) was predicted for another strain by this same acetylcholinesterase assay that, if confirmed by chemical analysis, would be the first report of anatoxin-a(S) in an Australian cyanobacterium.

Tumor necrosis factor-alpha promotes human papillomavirus (HPV) E6/E7 RNA expression and cyclin-dependent kinase activity in HPV-immortalized keratinocytes by a ras-dependent pathway.

Tumor necrosis factor-alpha (TNF-alpha) inhibits growth of normal cervical keratinocytes but stimulates proliferation of human papillomavirus (HPV)-immortalized and cervical carcinoma-derived cell lines when mitogens such as epidermal growth factor (EGF) or serum are depleted. Current work identifies the mechanism of growth stimulation. TNF-alpha promoted cell cycle progression by increasing expression of HPV-16 E6/E7 RNAs and enhancing activity of cyclin-dependent kinase (cdk)2 and cdc2 after 3 d. Increased kinase activity was mediated by upregulation of cyclins A and B and decreases in cdk inhibitors p21(waf) and p27(kip). TNF-alpha stimulated these changes in part by increasing transcription and stabilization of RNA for amphiregulin, an EGF receptor ligand, and amphiregulin directly increased HPV-16 E6/E7 and cyclin A RNAs. To define which components of the EGF receptor signaling pathway were important, HPV-immortalized cells were transfected with activated or dominant negative mutants of Ha-ras, raf, or MAPKK. Expression of activated Ha-ras maintained HPV-16 and cyclin gene expression and promoted rapid growth in the absence of EGF. Furthermore, ras activation was necessary for TNF-alpha mitogenesis as transfection with a dominant negative ras mutant (Asn-17) strongly inhibited growth. Thus, activation of ras promotes expression of HPV-16 E6/E7 RNAs, induces cyclins A and B, and mediates growth stimulation of immortal keratinocytes by TNF-alpha. These studies define a pathway by which ras mutations, which occur in a subset of cervical cancers, may contribute to pathogenesis. Mol. Carcinog. 27:97-109, 2000. Published by Wiley-Liss, Inc.

Preliminary evidence of toxicity associated with the benthic cyanobacterium Phormidium in South Australia.

In April 2000, the water supply for Yorke Peninsula in South Australia was deemed non-potable when extracts from a proliferation of the benthic cyanobacterium Phormidium aff. formosum in Upper Paskeville Reservoir were found to be lethally toxic by intraperitoneal injection into mice (400 mg kg-1). Routine water quality monitoring had failed to detect the development of the Phormidium until complaints of musty taste and odour, attributable to the production of 2-methyl-isoborneol (MIB), were received from the consumers. The 185 ML open-balancing storage, receiving filtered and chloraminated water from the River Murray, was isolated from the drinking water supply and a health alert was issued to approximately 15,000 consumers. The identity of the toxin(s) is thus far unknown, but clinical symptoms of toxicity in mice and chemical characteristics are distinct from the known major cyanotoxins. Preliminary characterisation of this toxin indicates that it has low solubility in water and organic solvents and is strongly associated with the particulate cellular material of the filaments. Toxicity of extracts was diminished by boiling and by treatment with chlorine, but not by chloramines. Further testing of floating cyanobacterial mats in the Torrens Lake in the city of Adelaide (Phormidium aff. formosum) and Myponga Reservoir (Phormidium aff. amoenum) in 2000/2001 was also found to be toxic by mouse bioassay. Toxicity is yet to be confirmed in monospecific cultured strains and further studies are required to identify the toxin and assess its health significance. Genetic characterisation of isolates has commenced in an attempt to classify their relatedness and to assist in the rapid identification of potentially toxic strains.