Controlled fabrication of nanopores using a direct focused ion beam approach with back face particle detection.

We report a direct, ion drilling technique that enables the reproducible fabrication and placement of nanopores in membranes of different thickness. Using a 30 keV focused Ga ion beam column combined with an in situ, back face, multi-channelplate particle detector, nanopores are sputtered in Si(3)N(4) and W/Si(3)N(4) to have diameters as small as 12 nm. Transmission electron microscopy shows that focused ion beam-drilled holes are near-conical with the diameter decreasing from entry to exit side. By monitoring the detector signal during ion exposure, the drilled hole width can be minimized such that the exit-side diameter is smaller than the full width at half-maximum of the nominally Gaussian-shaped incident beam. Judicious choice of the beam defining aperture combined with back face particle detection allows for reproducible exit-side hole diameters between 18 and 100 nm. The nanopore direct drilling technique does not require potentially damaging broad area exposure to tailor hole sizes. Moreover, this technique successfully achieves breakthrough despite the effects of varying membrane thickness, redeposition, polycrystalline grain structure, and slight ion beam current fluctuations.

A clinical study of hypoxia and metallothionein protein expression in squamous cell carcinomas.

The objective was to discover whether the oxygen-regulated protein, metallothionein, is expressed in the hypoxic cells of squamous cell carcinomas. Twenty patients with squamous cell carcinoma of the uterine cervix or head and neck were infused with a solution of the hypoxia marker, pimonidazole hydrochloride, at a dose of 0.5 g/m2. The following day, biopsies were collected, formalin fixed, paraffin embedded, and sectioned at 4 microm. Sections from each biopsy were immunostained for pimonidazole binding, metallothioneins I and II, involucrin, and proliferating cell nuclear antigen. A total of 84 biopsies were analyzed. Sixty-four of 84 biopsy sections contained hypoxia. Of the hypoxia-containing sections, 43 of 64 or 67% showed no microregional overlap between hypoxia and metallothionein; 7 of 64 showed overlap; and 14 of 64 showed a combination of overlap and no overlap. On a tumor-by-tumor basis, 5 of 7 head and neck and 7 of 13 cervix tumors showed no overlap between metallothionein and hypoxia at the microregional level. Ranges for the percentage of the area of hypoxia in head and neck (<0.9 to 17%) and cervix (<0.1 to 14%) tumors were similar. In the hypoxia-containing sections, immunostaining for involucrin, a molecular marker for differentiation, overlapped with that for hypoxia in 82% of the cases. The majority of hypoxic cells in squamous cell carcinomas do not express metallothionein protein, although metallothionein is induced by hypoxia in human tumor cells in vitro. Hypoxic cells in human tumors tend to be in regions immunostaining for involucrin, and it seems possible that differentiation of hypoxic cells in squamous cell carcinomas might affect metallothionein I and II expression.

Advances in non-nicotine pharmacotherapy for smoking cessation.

Progress in understanding the pharmacological nature of tobacco addiction, along with the modest success rates achieved by the nicotine replacement therapies, has provided the major impetus for the development of non-nicotine drugs as smoking cessation aids. This article reviews evidence from controlled trials of several non-nicotine medications for the treatment of nicotine dependence. Clonidine was the first non-nicotine medication to show efficacy for smoking cessation in multiple studies, but its effect was found to be limited at best. Positive results across several trials have been consistently demonstrated for amfebutamone (bupropion). Encouraging results have also been observed for nortriptyline and moclobemide. Studies of combined treatments using non-nicotine medications (amfebutamone, mecamylamine, oral dextrose) with nicotine replacement therapy suggest increased efficacy relative to treatments using one or the other treatment strategy alone. Thus, available evidence indicates that non-nicotine drug treatments offer a promising panoply of therapeutic strategies for the addicted smoker.

Pimonidazole: a novel hypoxia marker for complementary study of tumor hypoxia and cell proliferation in cervical carcinoma.

BACKGROUND: Tumor hypoxia may be associated with treatment resistance, cell proliferation, and metastatic potential, which contribute to poor prognosis. Complementary techniques for detecting hypoxia, cell growth, and metastases are required to study these relationships. OBJECTIVES: The purpose of this study was to demonstrate the clinical feasibility of quantitative hypoxia detection with pimonidazole, a novel hypoxia marker, and to correlate hypoxia with S-phase markers of tumor proliferation. METHODS: Pimonidazole binds to thiol-containing proteins specifically in hypoxic cells. Ten patients with cervical carcinoma received 0.5 g/m2 pimonidazole intravenously followed by biopsy of the cervical carcinoma the next day. Hypoxic cells were recognized by immunohistochemical detection of pimonidazole using a mouse monoclonal antibody. Cell proliferation was detected with a commercially available monoclonal antibody for proliferating cell nuclear antigen (PCNA). Assessment of hypoxia and cell proliferation was made qualitatively with light microscopy and quantitatively using point counting and image analysis software methods. RESULTS: No clinical toxic effects were associated with pimonidazole administration. Immunostaining with pimonidazole antibody was observed in 9 of 10 tumors, suggesting that hypoxia is a common occurrence in cervical carcinoma. Quantitatively, tumors that had large numbers of hypoxic cells had the greatest percentage of S-phase cells, but some tumors with smaller amounts of hypoxia also had substantial numbers of S-phase cells. CONCLUSION: Pimonidazole can be used for qualitative and quantitative assessment of tumor hypoxia.

Hypoxia and vascular endothelial growth factor expression in human squamous cell carcinomas using pimonidazole as a hypoxia marker.

Hypoxia in human tumors is associated with poor prognosis, but the molecular mechanisms underlying this association are poorly understood. One possibility is that hypoxia is linked to malignant progression through vascular endothelial growth factor (VEGF) induction and the associated angiogenesis and metastasis. The present clinical study measures hypoxia and VEGF expression on a cell-by-cell basis in human squamous cell carcinomas to test the hypothesis that hypoxia and VEGF protein expression are coupled in human tumors. Eighteen patients with invasive squamous cell carcinoma of the uterine cervix and head and neck have been investigated by a quantitative image analysis of immunostained sections from their tumors. The hypoxia marker pimonidazole was used to measure tumor hypoxia, and a commercially available antibody was used to measure VEGF protein expression. A quantitative immunohistochemical comparison of hypoxia and VEGF protein expression revealed no correlation between the two factors.

Hearts and minds: suicide among United States combat troops in Vietnam, 1957-1973.

The literature on suicides among military personnel in a combat zone remains anecdotal. Although one finds literary and journalistic accounts of the problem, it has not been systematically analyzed. This paper will examine suicides among American combat troops during their tour of duty in Vietnam. Utilizing statistical data from the Southeast Asia Combat Area Casualties Database (SACACD), the authors will survey its epidemiology among U.S. ground troops in Vietnam from 1957 to 1973. The results suggest that certain types of combat troops were significantly more likely than others to commit suicide. These findings not only provide important predictors for military health professionals in the assessment of suicide risk, they also raise disturbing questions about the nature of organized armed conflict.

"Puss caterpillar" envenomation: a report from North Carolina.

A 41-year-old white man with no specific past medical history presented to the Emergency Department on October 13, 1997, following what he described as a "caterpillar bite." The insect was subsequently identified as a "puss caterpillar" (Megalopyge opercularis). The patient experienced immediate excruciating pain that radiated throughout his left arm and gradually spread to the left chest area. He presented to a nearby emergency department several hours later and received treatment. The patient was subsequently admitted for observation and released several days later. Viewed in the context of previous clinical reports, this case highlights the broad range of clinical symptoms that can result from the puss caterpillar sting.

Tanning facility compliance with state and federal regulations in North Carolina: a poor performance.

BACKGROUND: Little is known about the compliance of commercial tanning facilities with regulations governing their operation. We inspected some tanning parlors to assess the degree to which they follow federal and North Carolina state regulations. METHODS: An inspection of 32 tanning facilities was conducted between March and May 1991 as part of an ongoing effort to educate tanning parlor operators and proprietors about UV light safety. Compliance with each of 21 distinct state and federal requirements was recorded for each facility. RESULTS: Only 1 of 32 facilities was in complete compliance with both state and federal regulations. The number of infractions ranged from none to 21 (mean [+/- SD] 7.1 +/- 4.1). Nineteen percent of facilities had timers that were not within the required +/- 10% accuracy level. Twenty-two percent also had timers that did not meet Code of Federal Regulations standards. The estimated proportion of the total light output in the UVB spectrum ranged from 0.5% to 5.0% (mean 4.25% +/- 0.95%). CONCLUSIONS: These limited data suggest that many commercial tanning establishments are not uniformly compliant with regulations. Although we cannot extrapolate these findings to other states, we anticipate that facilities in states with less rigorous regulations than North Carolina have similar or inferior safety profiles.

Lead-induced leukocytosis in female mice.

Lead acetate was shown to stimulate a striking leukocytosis in young adult female mice. The effect was manifest 4 days after lead injection and continued throughout the following 4 days. At the higher treatment level, lead induced an increase of 300% for both monocytes and neutrophils. The leukocytosis was due primarily to the elevated levels of neutrophils as suggested by a decrease in the ratios of peripheral agranulocytes to granulocytes. No differences from normal leukocyte cytology were observed in blood samples collected from animals receiving lead.