Design and characterization of a tissue-equivalent CVD-diamond detector for clinical dosimetry in high-energy photon beams.

New solid-state detectors, based on chemical vapour deposited (CVD) polycrystalline diamonds produced by hot-filament (HF) or microwave plasma (MW) assisted deposition methods, were constructed for radiation therapy dosimetry. Properties of diamond crystals, such as high radiation sensitivity, resistance to radiation damage and tissue-equivalence giving a low-energy dependence are very advantageous for clinical dosimetry. Therefore the encapsulation was specially designed for these detectors to have as little influence as possible on the radiation response. The prototypes were irradiated with use of a wide range of photon beam qualities ((60)Co gamma-rays, 6 and 18 MV X-rays). The radiation sensitivity varied considerably between samples deposited with HF (9 nC Gy(-1)mm(-3)) and MW (66 and 144 nC Gy(-1)mm(-3)) methods. For all detectors the leakage current was of the order of 10% of the radiation-induced current (bias voltage 100 V, dose rate 0.3 Gy/min). When irradiated with (60)Co gamma-rays, the detectors showed a dose-rate linearity with an exponential Delta parameter close to unity. However, a difference of 8% was found between Delta values for the different beam qualities. A small energy dependence was observed, for which the most probable sources are interface effects due to the silver electrodes and partly the geometry of the encapsulation which needs to be further optimized. Despite some limitations in the performance of present prototype detectors, with an improved CVD technique producing crystals of better electrical and dosimetric properties, and with a well-designed tissue-equivalent encapsulation, CVD-diamonds could serve as very good dosimeters for radiotherapy.

Quantization of 2D hole gas in conductive hydrogenated diamond surfaces observed by electron field emission.

Discrete jumps are observed in the emitted current density (J) versus extraction electric field (E) curves in electron field emission measurements from a conductive, hydrogen-terminated air-exposed diamond surface. These jumps are well reproduced by computations based on the assumption that a 2D nanoscale quantum system with discrete energy levels exists in the diamond near-surface layer. The present results confirm the formation of well-defined quantum states of holes in the 2D surface layer present on hydrogenated air-exposed diamond surfaces.

A preliminary dosimetric characterization of chemical vapor deposition diamond detector prototypes in photon and electron radiotherapy beams.

Three radiation detectors based on polycrystalline diamond films with different thickness and resistivity, obtained by microwave chemical vapor deposition, were tested to assess their suitability for relative dosimetry of photon and electron beams supplied by clinical linear accelerators. All samples showed a linear response as a function of the absorbed dose. The sensitivity per unit of detector sensitive volume spanned between 7 and 43 nC Gy(-1) mm(-3) with an applied electric field of 40 kV/cm. The dose rate dependence was evaluated following the Fowler theory and delta coefficient values between 0.95 and 1.00 were found for the three samples when polarized at 40 kV/cm. Percentage depth dose curves, output factors, and normalized dose profiles were determined for 6 and 10 MV photon beams and for 6 and 15 MeV electron beams. The results obtained with the diamond detectors were in good agreement with those obtained by reference detector measurements [all the data were within the experimental uncertainty of 1% (1sigma)].

Ageing of human epidermis: the role of apoptosis, Fas and telomerase.

BACKGROUND: Aged human epidermis is characterized by morphological changes including flattening of the dermal-epidermal junction and a decrease in thickness. OBJECTIVES: To determine the roles of proliferation, apoptosis, Fas (CD95), Fas ligand (FasL) and telomerase in changes of human epidermis during ageing. METHODS: Human epidermis from aged subjects (n = 14; mean age 70.7 years) and young subjects (n = 14; mean age 23.4 years) was studied by histology, immunohistochemistry, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling assay for apoptotic cells and reverse transcription-polymerase chain reaction to determine epidermal thickness, proliferation (Ki-67), apoptosis, expression of Fas and FasL, and telomerase activity. RESULTS: Aged skin was associated with thinning of the epidermis, decreased proliferation, and increased apoptosis below the granular layer. This was associated with increased epidermal expression of Fas and FasL. Telomerase activity was similar in aged and young epidermis. CONCLUSIONS: Fas/FasL-mediated apoptosis, along with decreased proliferation, may have a role in changes of human epidermis during ageing. Telomerase activity did not appear to be limiting in young vs. old human epidermis.

First-trimester screening for aneuploidy with fetal nuchal translucency in a United States population.

OBJECTIVE: To examine the detection rate of chromosomal abnormalities using a combination of nuchal translucency (NT) and maternal age in a United States population. METHODS: A total of 2131 pregnancies with 2339 fetuses underwent NT screening from April 2000 to April 2002 in our ultrasound unit. Nuchal translucency was measured from 11 to 14 weeks' gestation. Fetal crown-rump length (CRL) was also measured. The risk for trisomy 21 was calculated from a combination of maternal age and fetal NT with the use of software provided by The Fetal Medicine Foundation (FMF). Sensitivity and false-positive rates were calculated for different risk cut-offs. RESULTS: Chromosomal defects were diagnosed in 32 cases, including 12 cases of trisomy 21 and 10 cases of trisomy 18. The estimated risk based on maternal age and fetal NT was 1 in 300 or greater in 195 (8.3%) cases and these included 10/12 (83.3%) pregnancies with trisomy 21 and 9/10 (90.0%) pregnancies with trisomy 18. CONCLUSION: A combination of maternal age and fetal NT provides an effective method of screening for chromosomal defects. Using ultrasound techniques and risk algorithms from The FMF, the performance of the test in an American population is similar to that described in international populations.

Melanocyte-associated T cell epitopes can function as autoantigens for transfer of alopecia areata to human scalp explants on Prkdc(scid) mice.

Alopecia areata is a tissue restricted autoimmune condition affecting the hair follicle, resulting in hair loss. The goal of this study was to test the hypothesis that the autoantigen of alopecia areata is melanocyte associated. Potential autoantigens were tested in the human scalp explant/Prkd(scid) CB-17 mouse transfer system. Scalp T cells from lesional (bald) alopecia areata scalp were cultured with antigen-presenting cells, and antigen, along with interleukin-2. The T cells were then injected into autologous lesional scalp grafts on SCID mice, and hair regrowth was measured. Hair follicle homogenate was used as an autoantigen control. T cells cultured with melanoma homogenate induced statistically significant reduction in hair growth (p <0.01 by ANOVA). HLA-A2-restricted melanocyte peptide epitopes were then tested with lesional scalp T cells from HLA-A2-positive alopecia areata patients. Melanocyte-peptide-activated T cells significantly reduced the number of hairs regrowing in two experiments with six patients (p <0.001 by ANOVA). Injected scalp grafts showed histologic and immunochemical changes of alopecia areata. The most consistent peptide autoantigens were the Gp100-derived G9-209 and G9-280 peptides, as well as MART-1 (27-35). Melanocyte peptide epitopes can function as autoantigens for alopecia areata. Multiple peptides were recognized, suggesting epitope spreading.

Sweet's syndrome in association with Crohn's disease.

A case of Sweet's syndrome in association with Crohn's disease in a young woman is reported. Sweet's syndrome is a rare extraintestinal manifestation of Crohn's disease and ulcerative colitis.

Experimental rationale for treatment of high-risk human melanoma with zinc chloride fixative paste. Increased resistance to tumor challenge in murine melanoma model.

BACKGROUND: Fixed-tissue micrographic surgery (Mohs) of melanoma has been shown by retrospective analysis to improve 5-year survival. OBJECTIVES: To determine whether zinc chloride fixative paste acts as an immune adjuvant to increase host resistance to melanoma. METHODS: We performed a murine study using the poorly immunogenic B16 melanoma of C57Bl6J mice, and the more immunogenic K1735p melanoma of C3H/HeN mice. Tumors were treated with zinc chloride paste and excised 24 hours later (Group 1), or simply excised (Group 2). Mice were challenged 7 days later with injection of melanoma cells at a distant site, and tumor growth in this second site was followed. RESULTS: K1735p melanomas developed at the challenge site in 69% of mice treated with excision versus 32% of mice treated with zinc chloride fixation (P < 0.025). Development of B16 melanoma was not altered by zinc chloride fixation. CONCLUSION: Zinc chloride fixation of the more immunogenic K1735p melanoma increased resistance to subsequent tumor challenge, suggesting that zinc chloride fixative paste acts as an immune adjuvant.

Induction of hapten-specific tolerance of human CD8+ urushiol (poison ivy)-reactive T lymphocytes.

The interaction of CD28 with B7 molecules (CD80 or CD86) is an essential second signal for both the activation of CD4+ T cells through the T-cell receptor and the prevention of anergy. We studied the requirement of hapten-specific human CD8+ cells for CD28 co-stimulation in recognition of hapten, and anergy induction. Urushiol, the immunogenic hapten of poison ivy (Toxicodendron radicans), elicits a predominantly CD8+ T-cell response. Autologous PBMC were pre-incubated with urushiol prior to fixation by paraformaldehyde. Fixed antigen-presenting cells were unable to present urushiol to human CD8+ urushiol-specific T cells. Addition of anti-CD28, however, overcame this antigen-presenting defect, enabling CD8+ cells to proliferate. Fixation of antigen-presenting cells prevents upregulation of B7, and addition of anti-CD28 substitutes for this signal. Proliferation of CD8+ T cells in response to urushiol was blocked by CTLA4Ig, a recombinant fusion protein that blocks CD28/B7 interactions. Preincubation of urushiol-specific CD8+ cells with fixed PBMC + urushiol for 7 d induced anergy. Anergic CD8+ cells were viable and able to proliferate in response to IL-2, but not in response to urushiol. Induction of anergy required the presence of urushiol, and pre-incubation with irradiated PBMC + urushiol did not have this effect. It is proposed that anergy was induced by presentation of urushiol by fixed PBMC, in the absence of adequate co-stimulation signals. Induction of anergy by blocking of co-stimulation could potentially induce clinical hyposensitization to haptens.

Favourable melanoma prognosis associated with the expression of the tumour necrosis factor receptor and the alpha1beta1 integrin: a preliminary report.

Recently we encountered a patient (p1) with a Clark's level IV melanoma associated with recurrent cutaneous metastasis who subsequently experienced a complete remission after a period of therapy with dichloronitrobenzene (DCNB) and interferon-alpha (IFNalpha). Another patient (p2) with a similar Clark's level of disease but with a fatal prognosis and melanoma cells from the Sk-Mel 28 and MeWo cell lines served as control groups. Since cytokines and members of the alpha1 integrin family have been implicated in the growth and metastatic behaviour of melanomas, we evaluated the cytokine effects and integrins expressed by melanoma cells in the patients' tumours. P1, but not p2 nor MeWo melanoma cells, expressed HLA-DR, alpha1beta1 and the tumour necrosis factor receptor (TNF-R). Culturing p1 melanoma cells with TNFalpha, but not MeWo or p2 melanoma cells, increased their expression of alpha1beta1 integrin and was cytotoxic for the cells. Significant in vivo growth of metastatic p1 and p2 melanoma explants as well as MeWo cells grafted subcutaneously onto nude mice was noted over 36 days. Intralesional injection of TNFalpha induced complete regression of p1 explants, but not of p2 or MeWo explants. Intralesional injection of IFNalpha or anti-alpha1beta1 integrin arrested p1 graft growth. These results suggest that the slow growth of the melanoma cells in nude mice, as well as the susceptibility to tumour killing by TNFalpha and the dependence of the tumour on signals mediated by the alpha1beta1 integrin are features that may have contributed to the beneficial therapeutic response in patient 1.

In vivo effects of cytokines on psoriatic skin grafted on nude mice: involvement of the tumour necrosis factor (TNF) receptor.

Following engraftment of human involved psoriatic skin to nude mice there is a partial normalization of pathology associated with a loss of inflammatory leucocytes. However, the epidermis remains hyperproliferative, which may reflect a primary defect. The roles of TNF-alpha, IL-1 and IL-6 in epidermal hyperproliferation of grafted psoriatic lesions were investigated. Before and after treatment, grafts were analysed to determine epidermal thickness and labelling index (LI). HLA-DR, intercellular adhesion molecule-1 (ICAM-1), and TNF receptor (TNF-R; p75 and p55) expression were determined by immunoperoxidase staining. Psoriatic epidermis was found consistently to be negative for p55 TNF-R and p75 TNF-R before grafting. Following engraftment, TNF-R-positive cells (i.e. p55 by keratinocytes; p75 by epidermal dendritic cells) were identified throughout the epidermis. Higher numbers of p75 TNF-R epidermal dendritic cells were found in grafts following a course of TNF-alpha, IL-6 or IL-1 treatment. The p55 form of the TNF-R expressed by keratinocytes was significantly elevated after treatment with TNF-alpha or IL-6. HLA-DR and ICAM-1 were also expressed in these grafts. TNF-alpha, anti-IL-1, and anti-IL-6 treatment induced a marked decrease in the epidermal thickness and LI of psoriatic graft tissue, correcting the hyperproliferation associated with psoriatic epidermis. Supraphysiological levels of TNF-alpha may saturate and consequently down-regulate their own receptors, leading to a paradoxical inhibitory effect.

Costs of potential complications of care for major surgery patients.

We examined computerized hospital discharge abstract data from 372,680 major surgery patients admitted to 404 California acute care hospitals in 1988 to identify potential complications of care. At least one potential in-hospital complication occurred for 10.8% of patients. Patients with complications were older and more likely to die in-hospital (9.4% compared to 1.0%, P < 0.0001). On average, patients with complications had longer stays (13.5 versus 5.4 days, p < 0.0001) and higher total charges ($30,896 versus $9,239, p < 0.0001). After adjusting for demographic, clinical, and hospital factors, patients with potential complications averaged $16,023 higher total hospital charges than uncomplicated patients. Complications were associated with 96.6% (95% confidence interval = 95.2%, 98.0%) higher hospital charges after adjusting for these factors. Across all patients, complications were related to over $647 million in additional total hospital charges for these major surgery patients.

Association of treatment-resistant chronic Lyme arthritis with HLA-DR4 and antibody reactivity to OspA and OspB of Borrelia burgdorferi.

Chronic Lyme arthritis that is unresponsive to antibiotic therapy is associated with an increased frequency of the HLA-DR4 specificity. To determine whether the immune response to a particular polypeptide of Borrelia burgdorferi may be associated with treatment-resistant chronic Lyme arthritis, we correlated the clinical courses and HLA-DR specificities of 128 patients with Lyme disease with their antibody responses to spirochetal polypeptides. Antibody reactivity was determined by Western blotting (immunoblotting) with sonicated whole B. burgdorferi and recombinant forms of its outer surface proteins, OspA and OspB, as the antigen preparations. Of 15 patients monitored for 4 to 12 years, 11 (73%) developed strong immunoglobulin G responses to both OspA and OspB near the beginning of prolonged episodes of arthritis, from 5 months to 7 years after disease onset. When single serum samples from 80 patients with Lyme arthritis, were tested, 57 (71%) showed antibody reactivity to recombinant Osp proteins; in contrast, none of 43 patients who had erythema migrans or Lyme meningitis (P < 0.00001) and 1 of 5 patients who had chronic neuroborreliosis but who never had arthritis (P = 0.03) showed antibody reactivity to these proteins. Among the 60 antibiotic-treated patients with Lyme arthritis, those with the HLA-DR4 specificity and Osp reactivity had arthritis for a significantly longer time after treatment than those who lacked Osp reactivity (median duration, 9.5 versus 4 months; P = 0.009); a similar trend was found for the HLA-DR2 specificity. For other HLA-DR specificities, arthritis resolved within a median duration of 2 months in both Osp-reactive and nonreactive patients. We conclude that the combination of the HLA-DR4 specificity and OspA or OspB reactivity is associated with chronic arthritis and the lack of a response to antibiotic therapy.

Unilateral linear lichenoid eruption after bone marrow transplantation: an unmasking of tolerance to an abnormal keratinocyte clone?

Chronic cutaneous graft-versus-host disease may appear clinically as a lichenoid eruption. We describe a 26-year-old man who developed a unilateral linear lichenoid eruption 7 months after allogeneic bone marrow transplantation. We believe this represents an unusual form of localized, chronic graft-versus-host disease. The possible relationship to viral infection or cellular mosaicism and the clinical, histologic, and immunologic similarities to idiopathic lichen planus are discussed.

Alopecia areata. Autoreactive T cells are variably enriched in scalp lesions relative to peripheral blood.

BACKGROUND AND DESIGN: Alopecia areata is a condition characterized by hair loss in association with perifollicular infiltration of T cells and antigen-presenting cells. Autoreactive T cells are postulated to amplify this abnormality by interacting with DR+ follicular epithelium. These cells may recognize either autologous major histocompatibility complex class II antigen or an autoantigen restricted by major histocompatibility complex class II. Limiting dilution analysis was used to determine the frequency of autoreactive lymphocytes in scalp biopsy specimens and peripheral blood from seven adult patients with alopecia areata. Autoreactive T cells are defined for this study as those that proliferate in response to autologous irradiated peripheral blood mononuclear cells. RESULTS: Autoreactive lymphocytes were enriched in scalp biopsy specimens relative to peripheral blood in five of seven patients. This enrichment was statistically significant in four of five patients. Five autoreactive T-cell clones derived from lesional scalp were characterized. Four of these clones were CD3+CD4+CD8- and one clone was CD3+CD4-CD8+. CONCLUSIONS: Enrichment of autoreactive cells in lesions of alopecia areata supports a role for these cells in the pathogenesis of this condition. Enrichment of autoreactive lymphocytes is also found in allergic contact dermatitis. Thus, these autoreactive lymphocytes may have a general role in inflammation.

Leiomyoma in the hand. A case report.

A 60-year-old woman developed an avascular leiomyoma arising from a digital artery in the thumb and was successfully treated by en bloc excision. Leiomyomas in the hand are very rare, and thus the diagnosis will seldom be made on clinical evaluation. They may be more painful than other common, benign tumors, however, and may originate from a digital artery. Preoperative evaluation of vascular function may give a clue to the presence of a leiomyoma. A spectrum of vascular smooth-muscle tumors from very vascular to relatively avascular is noteworthy.

A polyclonal CD4+ and CD8+ lymphocytosis in a patient doubly infected with HTLV-I and HIV-1: a clinical and molecular analysis.

HTLV-I is associated with adult T-cell leukemia/lymphoma (ATL) characterized by monoclonal expansions of CD4+ T-lymphocytes. In this report we describe a histologically benign, polyclonal HTLV-I infection in a patient exhibiting both an absolute CD4+ and CD8+ lymphocytosis. Three T-cell lines containing integrated HTLV-I proviral copies established from this patient were initially polyclonal, but with time all grew out the same two clones as determined by analysis of their T-cell antigen receptor beta chain gene rearrangements. The patient subsequently developed pulmonary and nasopharyngeal nodules containing HTLV-I infected cells. Restriction analysis of the patient's HTLV-I provirus revealed no differences from prototype HTLV-I and the tax gene was normally expressed in vivo and in vitro. The patient's T-lymphocytosis and HTLV-I+ pulmonary tract nodules were put into a complete clinical remission by treatment with alkylating agents and steroids. Subsequently, the patient developed a severe immunodeficiency state and expired. Retrospective serologic and gene amplification assays for HIV-1 demonstrated that he had been doubly infected from the time of presentation. Postmortem analysis by polymerase chain reaction revealed the presence of both HTLV-I and HIV-1 in lymphatic tissues and the testes; HIV-1 was also detected in brain tissue.

Non-specifically activated human peripheral blood mononuclear cells are cytotoxic for human keratinocytes in vitro.

Cultured human keratinocytes were lysed by activated PBMC in a 4-h 51Cr release assay. PBMC were activated by incubation with 50 U/ml of rIL-2 for 4 days. The cytotoxic precursors were found to be NKH1+ and included both CD2+ and CD2- phenotypes. This cytotoxicity was not genetically restricted, as cells killed both allogeneic and autologous keratinocytes without priming. Cytotoxicity was blocked by pre-incubation of effector cells with mAb against LFA-1 alpha-(TS1/22) and beta-chains (TS1/18), but not by antibodies directed against CD4, CD8, or leukocyte common Ag (T200) suggesting that LFA-1 is an important interactive molecule in this cytotoxicity. IFN-gamma is reported to upregulate ICAM-1, the ligand for LFA-1. Pre-treatment of target keratinocytes with IFN-gamma was also found to greatly increase the sensitivity of keratinocytes to lysis. This increased sensitivity to lysis was blocked by anti-LFA-1 and anti-ICAM-1, but not by anti-DR (L243), and thus was not the result of increased DR expression. Such treated targets were lysed at low levels (15 to 18%) by an Ag-specific CD8+ cytotoxic clone as well as a T cell line derived from a skin lesion of allergic contact dermatitis. In contrast, control keratinocytes were only sensitive to IL-2-activated PBMC as described above. The above findings may be relevant to a variety of conditions in which epidermal damage is associated with lymphocytic infiltrate. These conditions include graft-vs-host disease, erythema multiforme, and lupus erythematosus. DR+ keratinocytes, which may be a marker for IFN-gamma are also found in the above conditions. It is suggested that epidermal pathology may be mediated by non-specific cytotoxicity induced in the course of an immune response.

Quantitation and cloning of human urushiol specific peripheral blood T-cells: isolation of urushiol triggered suppressor T-cells.

A limiting dilution assay was developed to quantitate urushiol (the antigen of poison ivy; Toxicodendron radicans) specific T cells from peripheral blood of a patient with a history of rhus (poison ivy) dermatitis. It was found that maximal sensitivity with minimal nonspecific proliferation could be produced with the use of 5 U/ml of recombinant IL2 added to the assay on day 6. This donor was found to have a frequency of urushiol specific peripheral blood T cells of (1/2935). Five interleukin 2 (IL2) dependent urushiol specific T-cell clones were generated from the peripheral blood of this patient. These T-cell clones had a CD8+ (T8+) phenotype and proliferated specifically to both extracts of Toxicodendron radicans (poison ivy) leaves and pure urushiol. Pentadecylcatechol was an inferior antigen, only stimulating proliferation of one clone. The ability of all clones to proliferate to pure urushiol, despite their having been induced with leaf extract, suggests that urushiol, or closely related catechols, represent the only allergenic constituents of Toxicodendron radicans. Lymphokine production in response to antigen varied between (0.6-5.0) units/ml of interleukin 2 (IL2) and (1.0-120) units/ml of gamma interferon. Although none of the clones showed significant cytotoxicity against NK targets, three of five lines showed considerable cytotoxicity against concanavalin A treated (lectin approximated) targets. However, cytotoxicity for rhus conjugated autologous targets was not detected. It was found that several of these CD8+ clones could suppress IgG production in the presence of rhus antigen. The isolation of these T-cells from peripheral blood several months after rhus dermatitis suggests that these clones may have a role in down regulating delayed hypersensitivity to urushiol.

Enzymatic amplification of HTLV-I viral sequences from peripheral blood mononuclear cells and infected tissues.

Human T-cell lymphotropic virus type I (HTLV-I) and human T-cell lymphotropic virus type II (HTLV-II) have been associated with adult T-cell leukemia/lymphoma (ATL) and a rare T-cell variant of hairy cell leukemia, respectively. Direct detection of viral nucleic acid in peripheral blood lymphocytes (PBLs) and infected tissues in carrier patients and those with chronic disease has proven refractory due to viral transcriptional dormancy and the small number of infected cells present. The investigators report here the successful application of the DNA amplification procedure, termed PCR, to the detection of these human oncoviruses. Judicious selection of specific oligonucleotides for primers and probes provides type-specific and simultaneous detection of these two retroviruses. The ability to amplify and detect highly conserved regions of these medically relevant viruses may facilitate the identification of, as yet, uncharacterized retroviruses.