[Radiology seen in postal stamps (4)].
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Oxygen plasma-treatment is commonly used to increase the hydrophilicity of poly(dimethylsiloxane) (PDMS) stamps used for microcontact printing (muCP) aqueous-based inks. Review of the literature reveals that a wide range of plasma parameters are currently employed to modify stamp surfaces. However, little is known about the effect of these parameters (e.g., power, chamber pressure, duration) on the undesirable transfer of low-molecular-weight silicon-containing fragments from the stamps that commonly occurs during muCP. To study the effect of oxygen plasma-treatment on Si transfer, unpatterned PDMS stamps were treated with oxygen plasma under various conditions and used to stamp deionized water on plasma-activated poly(methyl methacrylate) (PMMA) substrates. Once stamped, the PMMA substrates were analyzed with X-ray photoelectron spectroscopy (XPS) to quantify and characterize silicon present on the substrate surface. In addition, used PDMS stamps were analyzed with scanning electron microscopy (SEM) to observe topographical changes that occur during oxygen plasma-treatment. XPS results show that all plasma treatments studied significantly reduced the amount of Si transfer from the treated stamps during muCP as compared to untreated PDMS stamps and that the source of transfer is residual PDMS fragments not removed by oxygen plasma. SEM results show that, although the treated stamps undergo a variety of topographical changes, no correlation exists between stamp topography and extent of Si transfer from the stamps.
CONTEXT: Many of the publicly available health quality report cards are based on administrative data. ICD-9-CM codes in administrative data are not date stamped to distinguish between medical conditions present at the time of hospital admission and complications, which occur after hospital admission. Treating complications as preexisting conditions gives poor-performing hospitals "credit" for their complications and may cause some hospitals that are delivering low-quality care to be misclassified as average- or high-performing hospitals. OBJECTIVE: To determine whether hospital quality assessment based on administrative data is impacted by the inclusion of condition present at admission (CPAA) modifiers in administrative data as a date stamp indicator. DESIGN, SETTING, AND PATIENTS: Retrospective cohort study based on 648,866 inpatient admissions between 1998 and 2000 for coronary artery bypass graft (CABG) surgery, coronary angioplasty (PTCA), carotid endarterectomy (CEA), abdominal aortic aneurysm (AAA) repair, total hip replacement (THR), acute MI (AMI), and stroke using the California State Inpatient Database which includes CPAA modifiers. Hierarchical logistic regression was used to create separate condition-specific risk adjustment models. For each study population, one model was constructed using only secondary diagnoses present at admission based on the CPAA modifier: "date stamp" model. The second model was constructed using all secondary diagnoses, ignoring the information present in the CPAA modifier: the "no date stamp model." Hospital quality was assessed separately using the "date stamp" and the "no date stamp" risk-adjustment models. RESULTS: Forty percent of the CABG hospitals, 33 percent of the PTCA hospitals, 40 percent of the THR hospitals, and 33 percent of the AMI hospitals identified as low-performance hospitals by the "date stamp" models were not classified as low-performance hospitals by the "no date stamp" models. Fifty percent of the CABG hospitals, 33 percent of the PTCA hospitals, 50 percent of the CEA hospitals, and 36 percent of the AMI hospitals identified as low-performance hospitals by the "no date stamp" models were not identified as low-performance hospitals by the "date stamp" models. The inclusion of the CPAA modifier had a minor impact on hospital quality assessment for AAA repair, stroke, and CEA. CONCLUSION: This study supports the hypothesis that the use of routine administrative data without date stamp information to construct hospital quality report cards may result in the mis-identification of hospital quality outliers. However, the CPAA modifier will need to be further validated before date stamped administrative data can be used as the basis for health quality report cards.
We conducted a pilot study to determine the most efficient mailing strategy for a postal questionnaire study among nurses in Ontario, Canada. Five mailing strategies involving types of stamps on the return envelopes were considered: no stamp, business-reply stamp, metered stamp, small regular stamp, and large commemorative stamp. We found that paper stamps, especially large commemorative stamps, on return envelopes increased the response rate and reduced the response time, as compared with other mailing strategies. Business-reply stamps had the lowest cost per response received and a low total cost.
Macromolecular microstamping with polydimethylsiloxane (PDMS) stamps has been demonstrated to transfer proteins onto glassy substrates for antigen or antibody detection and for cell patterning. For many applications, including neuronal cell patterning, it is important to assure reliable transfer of sufficient quantity of protein. Research has shown that protein transfer is enhanced with the selection of the proper protein-stamp-substrate combination. In addition, detergent studies have shown that detergent-protein complexes detach from surfaces to a greater extent than proteins alone. Therefore, we hypothesized that stamp surface modification (termed here a release layer) can enhance polylysine transfer and benefit cell growth on microstamped substrates. We found unmodified stamps to transfer insufficient polylysine to support good cell survival of hippocampal neurons in a widely used serum-free, reduced-glia cell culture system. However, with modified stamps neuronal growth was reliably good. This enhanced cell growth can be attributed to the increased polylysine transfer due to the release layer rather than increased loading onto the stamp. This enhancement was found to be even greater for two-month old stamps that were stored in water. Furthermore, the physicochemical properties of the release layer can modulate the loading process. Thus, our data supports the conclusions that the release layer: (1) modulates polylysine loading, (2) enhances polylysine transfer, (3) enhances cellular growth on microstamped substrates, and (4) extends the durability (defined as the number of times a stamp can be reused) of PDMS microstamps.
A benchtop method for the facile production of nanoscale metal structures on polymers is demonstrated. This approach allows for the design and patterning of a wide range of metallic structures on inexpensive polymer surfaces, affording the fabrication of nanoscaled platforms for use in the design of sensors, actuators, and disposable electronic and photonic devices. Numerous structures, from simple nanowires to multilayered metallic gratings, are demonstrated, with sizes ranging from microns to the nanoscale. The process involves molding a malleable metal film deposited on a rigid substrate such as mica, by the compression of a plastic polymer stamp with the desired pattern against the metal film. While under compression, an etchant is then used to modify the metal. Upon separation of the stamp from the support, micro- to nanoscaled metallic structures are found on the stamp and/or on the substrate. The sizes of the structures formed depend on the sizes of the features on the stamp but can be fine-tuned by about 4-fold through variations in both pressure and duration of etching. Also, depending on the processing, multiple dimension metallic structures can be obtained simultaneously in a single stamping procedure. The metallic structures formed on the stamp can also be subsequently transferred to another surface allowing for the construction of multilayered materials such as band gap gratings or the application of electrical contacts. Using this approach, fabrication of both simple and complex micro- to nanoscaled structures can be accomplished by most any researcher as even the grating structure of commercial compact disks may be used as stamps, eliminating the requirement of expensive lithographic processes to form simple structures.
The pharmacokinetics and toxicity profile of stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) were studied in beagle dogs and feline immunodeficiency virus-infected domestic cats. Therapeutic plasma concentrations of STAMP 3-4 logs higher than its IC50 value can be achieved after its p.o. administration to dogs as well as cats at the 100 mg/kg nontoxic dose level. In accordance with its safety profile in rodent species, a 4- to 7-week STAMP treatment course with twice daily administration of hard gelatin capsules containing 25-100 mg/kg (50-200 mg/kg/ day) STAMP was very well-tolerated by dogs and cats at cumulative dose levels as high as 8.4 g/kg. Except for the sporadic occurrence of nausea and vomiting after its administration and elevation of serum ALT levels in some of the cats, STAMP therapy was not associated with any clinical or laboratory evidence of toxicity. No STAMP-related toxic lesions were found in any of the organs from STAMP-treated cats or dogs. These findings encourage the further development of stampidine for possible clinical use in HIV-infected persons.
We have evaluated the clinical potential of stavudine-5'-(p-bromophenyl methoxyalaninyl phosphate(stampidine [STAMP]), a novel aryl phosphate derivative of stavudine, as a new anti-human immunodeficiency virus (anti-HIV) agent, by examining its acute, subacute, and chronic toxicity profile in mice as well as by testing its antiviral activity in a surrogate human peripheral blood lymphocyte (Hu-PBL)-SCID mouse model of human AIDS. STAMP was very well tolerated in BALB/c and CD-1 mice, without any detectable acute or subacute toxicity at single intraperitoneal or oral bolus doses as high as 500 mg/kg of body weight. Notably, daily administration of STAMP intraperitoneally or orally for up to 8 consecutive weeks was not associated with any detectable toxicity at cumulative dose levels as high as 6.4 g/kg. Micromolar concentrations of the active STAMP metabolite in plasma were rapidly achieved and maintained for more than 4 h after parenteral as well as oral administration of a nontoxic 100-mg/kg bolus dose of STAMP. In accordance with its favorable pharmacokinetic profile and in vitro potency, STAMP exhibited dose-dependent and potent in vivo anti-HIV activity in Hu-PBL-SCID mice against a genotypically and phenotypically nucleoside analog reverse transcriptase inhibitor (NRTI)-resistant clinical HIV type 1 (HIV-1) isolate (BR/92/019; D67N, L214F, T215D, K219Q) at nontoxic dose levels. The remarkable in vivo safety and potency of STAMP warrants the further development of this promising new antiretroviral agent for possible clinical use in patients harboring NRTI-resistant HIV-1.
A microstamping technique has been developed for high-resolution patterning of proteins on glass substrates for the localisation of neurons and their axons and dendrites. The patterning process uses a microfabricated polydimethylsiloxane stamp with micrometer length features to transfer multiple types of biomolecules to silane-derivatised substrates, using glutaraldehyde as a homobifunctional linker. To test the efficacy of the procedure, substrates are compared in which poly-d-lysine (PDL) was physisorbed and patterned by photoresist with those stamped with PDL. Fluorescein isothiocyanate labelled poly-l-lysine was used to verify the presence and uniformity of the patterns on the glass substrates. As a biological assay, B104 neuroblastoma cells were plated on stamped and physisorbed glass coverslips. Pattern compliance was determined as the percentage of cells on the pattern 8 h after plating. Results indicate that the stamping and photoresist patterning procedure are equivalent. Substrates stamped with PDL had an average pattern compliance of 52.6 +/- 4.4%, compared to 54.6 +/- 8.1% for physisorbed substrates. Measures of background avoidance were also equivalent. As the procedure permits successive stamping of multiple proteins, each with its own micropattern, it should be very useful for defining complex substrates to assist in cell patterning and other cell guidance studies.
A moderately hydrophilic, thermoplastic elastomer (poly(ether-ester)) was investigated as a stamp material for microcontact printing of a polar ink: pentaerythritol-tetrakis-(3-mercaptopropionate). Stamps with a relief structure were produced from this polymer by hot embossing, and a comparison was made with conventional poly(dimethylsiloxane) (PDMS) and oxygen-plasma-treated PDMS. It is shown that the hydrophilic stamps can be used for the repetitive printing (without re-inking) of at least 10 consecutive patterns, which preserve their etch resistance, and this in rather sharp contrast to conventional and oxygen plasma-treated PDMS stamps. It is argued that these enhanced printing characteristics of the hydrophilic stamps originate from an improved wetting and solubility of polar inks in the hydrophilic stamp.
This study compares the findings of multidisciplinary evaluation to the three-night use of the PotenTest, a standardized stamp test for the evaluation of nocturnal penile tumescence, in 174 patients. An organic etiology was diagnosed in 54% of those evaluated. The PotenTest proved accurate as a screening device for organic disease. Among the 48 patients who did not break any of the stamps over the three nights, 40 were found to have an organic basis for their erectile failure, for a predictive value of 83%. Among the 68 patients who broke all of the stamps, 45 were found to have a psychogenic basis for their erectile failure, for a 66% predictive value. When one or two of the stamps were broken over the three nights, the predictive values as to the etiology of the erectile failure were considerably diminished and of no diagnostic value. Results for only one night of usage revealed that of the 73 patients who did not break the stamps, 56 (77%) were found to have an organic etiology. Of the 101 patients who broke the stamps on the first night, 63 (62%) were found to have a psychogenic etiology.
The study examined the effects of homelessness on access to public entitlements (Medicaid and food stamp programs) in a soup kitchen population. Data were collected between 1997 and 1999 from a sample of 343 adults at two soup kitchen sites in New York City. Five hypotheses, focusing on the effects of housing status (literal homelessness, unstable housing, and domiciled), frequency of drug/heavy alcohol use, drug/alcohol-user treatment history and childcare responsibilities on access to Medicaid and food stamp programs were tested. Multiple logistic regression analysis indicated that both literal homelessness and unstable housing were associated with less access to Medicaid and food stamps. Other significant findings were: current drug/alcohol-user treatment experience was associated with greater access to both Medicaid and food stamps, frequency of drug/heavy alcohol use was associated with less access to Medicaid only, and caring for children was associated with greater access to food stamps only. These findings support the crucial role of housing status in mediating access to entitlements, and the importance of drug/alcohol-user treatment involvement as a cue to seeking entitlements. The need to reduce health disparities through active and sustained outreach programs designed to enhance homeless persons' access to Medicaid and food stamp programs was discussed.