Kinetics and mechanisms of chemical reactions in nonequilibrium-plasma etching of silicon and silicon compounds

Plasma-chemical etching of silicon and silicon compounds is reviewed. It is shown that present data indicates that fluorine atoms and molecules are the main particles responsible for etching of silicon and that atomic fluorine is the main active particle for etching of silicon dioxide. Insufficient data exists to establish the contribution of charged and excited states to the etching of silicon and its compounds but oxygen atoms and molecules are seen to have a strong influence and fluorocarbon radicals can passivate the surface by forming polymer films.     

Intravascular lymphomatosis: a case presenting with encephalomyelitis and reactive haemophagocytic syndrome diagnosed by renal biopsy

OBJECTIVE: To determine the frequency of characteristics associated with unprotected heterosexual intercourse in HIV infected adults in an urban area. DESIGN: Retrospective comparison of sexual risk transmission behaviour between HIV infected men and women from a drug treatment site and between women from the drug site and HIV infected women from an urban medical centre. METHODS: HIV infected women and men were asked questions on sexual behaviour for a 1 year period before enrollment. The outcome variable was heterosexual risk behaviour (HRB) defined as having vaginal sex at least once in the previous year and not always using condoms. RESULTS: 73% of the drug clinic females, 72% of the drug clinic males, and 42% of the medical centre female engaged in HRB. Using logistic regression analysis, women and men in drug treatment engaged in similar rates of HRB; however, women in drug treatment were four times (95% CI = 2.0-8.3) more likely to engage in HRB risk behaviour than women from the medical centre. CONCLUSION: The data suggest that a surprisingly large portion of HIV infected patients under treatment engaged in HRB, especially former drug users. Without specifically targeted interventions, the heterosexual spread of HIV in urban areas will continue to be a serious problem.     

Illegitimate recombination leading to allelic loss and unbalanced translocation in p53-mutated human lymphoblastoid cells

Allelic loss and translocation are critical mutational events in human tumorigenesis. Allelic loss, which is usually identified as loss of heterozygosity (LOH), is frequently observed at tumor suppressor loci in various kinds of human tumors. It is generally thought to result from deletion or mitotic recombination between homologous chromosomes. In this report, we demonstrate that illegitimate (nonhomologous) recombination strongly contributes to the generation of allelic loss in p53-mutated cells. Spontaneous and X-ray-induced LOH mutations at the heterozygous thymidine kinase (tk) gene, which is located on the long arm of chromosome 17, from normal (TK6) and p53-mutated (WTK-1) human lymphoblastoid cells were cytogenetically analyzed by chromosome 17 painting. We observed unbalanced translocations in 53% of LOH mutants spontaneously arising from WTK-1 cells but none spontaneously arising from TK6 cells. We postulate that illegitimate recombination was occurring between nonhomologous chromosomes after DNA replication, leading to allelic loss and unbalanced translocations in p53-mutated WTK-1 cells. X-ray irradiation, which induces DNA double-strand breaks (DSBs), enhanced the generation of unbalanced translocation more efficiently in WTK-1 than in TK6 cells. This observation implicates the wild-type p53 protein in the regulation of homologous recombination and recombinational DNA repair of DSBs and suggests a possible mechanism by which loss of p53 function may cause genomic instability.     

The functional outcome of lower-extremity fractures with vascular injury

Salvage of lower-extremity Gustilo type IIIC fractures is difficult, time-consuming for the patients and physicians, and not universally successful because of poor functional outcomes. Even if successful with limb salvage, the functional result may be unsatisfactory because of mutilating injuries to muscle and nerve, bone loss, and the presence of chronic infection. From July 1991 until July 1994, revascularizations of open IIIC fractures were attempted for wounds with Mangled Extremity Severity Score (MESS) < or = 10. The functional results were evaluated at 2 years after injury. Thirty-six lower-extremity revascularizations were performed on 34 patients, including 1 patient with bilateral distal tibial IIIC fractures and a child with IIIC femoral fracture accompanied by ipsilateral distal tibial amputation. Excluded were patients with below-ankle IIIC fractures as well as patients who underwent immediate amputation at admission. After the revascularization, seven patients with IIIC fractures (7 of 36, 19.4%) underwent secondary amputation within 1 week. At the 2-year follow-up, the overall secondary amputation rate was 25% (9 of 36) and the salvage rate was 75% (27 of 36). Those were no deaths. Of the 29 salvaged limbs among these 27 patients, 23 limbs (23 of 29, 79.3%) required secondary coverage procedures that included 12 free flap transfers (12 of 29, 41.4%). Every patient needed subsequent reconstructive surgery to achieve an acceptable functional result. In this series, MESS was able to predict the secondary amputation rate and the functional result. Sixteen of the 17 limb-salvaged patients with MESS < or = 7 were able to achieve minimal functional requirements, whereas 3 of the 10 patients with MESS = 8 to 10 failed to achieve minimal functional requirements at the 2-year follow-up. Using statistical analysis, we found that the salvaged limbs with MESS < or = 9 exhibited a significant difference in achieving adequate function compared with limbs with MESS > 9. Using our protocol for treatment for IIIC fractures, the threshold for immediate amputation can be raised from MESS = 7 to MESS = 9. Our conclusions are (1) more severely injured limbs have poor functional results, (2) every patient needs subsequent reconstructive surgery, and (3) the MESS may be helpful in decision-making.     

Laminin-6 and laminin-5 are recognized by autoantibodies in a subset of cicatricial pemphigoid

To aid treatment choice in early stage of Hodgkin's disease, we analysed patients registered in the IDHD Database with clinical stages I or II Hodgkin's disease who were not staged with laparotomy and whose initial treatment was with radiotherapy alone. The factors analysed for outcome after first relapse included initial stage, age, sex, histology, number of involved areas, mediastinal involvement, E-lesions, B-symptoms, erythrocyte sedimentation rate, alkaline phosphatase, serum albumin and haemoglobin. As well as presentation variables, we analysed the disease-free interval after initial radiotherapy and the extent of disease at relapse. A total of 1364 patients with clinical stage I or II Hodgkin's disease were treated with initial radiotherapy, of whom 473 relapsed. The probability of survival 10 years after relapse was 63%. For cause-specific survival (CSS), both multivariate and univariate analysis identified the importance of age at presentation and histological subtypes. When all causes of death were considered, the multivariate analysis identified age as the only significant factor. The length of initial disease-free interval had no influence on prognosis after relapse, but the 169 patients with nodal relapse had a higher cause-specific survival than those with an extranodal component of relapse (74% versus 51% at 10 years, P < 0.005). Thus, the important factors for outcome after initial treatment with radiotherapy are those factors predicting the risk of relapse after initial treatment together with those predicting outcome after relapse, namely age, histologic subtype and extent of disease at relapse.     

What is the current status of biochemical markers in the diagnosis, prognosis and monitoring of osteoarthritis?

Biochemical markers for osteoarthritis (OA) may serve different purposes. Since markers reflect ongoing dynamic metabolic processes in the joint tissues (cartilage, synovium, bone, etc.), they are most likely to be useful to predict prognosis and response to treatment, to monitor response to treatment, and for disease staging. Markers are currently being used at the research level for these purposes. The goal of using these markers to assess the disease process in the OA clinical trial setting or in the clinical routine has, however, not yet been reached.     

Nonsecretory IgA1 autoantibodies targeting desmosomal component desmoglein 3 in intraepidermal neutrophilic IgA dermatosis

Intraepidermal neutrophilic IgA dermatosis, a rare skin disease entity manifested with blisters and pustules clinically and lower epidermal blister, acantholysis, and neutrophilic infiltration pathologically, was first reported in 1985. Although the disease is characterized by IgA autoantibodies targeting the epithelial cell surface component, the target antigen has not been determined. We investigated a patient with this disease by histopathology, direct and indirect immunofluorescence, immunoblotting, and immunoadsorption studies. The pustular lesion was characterized by blister at the lower epidermis, acantholysis, and neutrophilic infiltration. Nonsecretory IgA1 subclass autoantibodies targeting the lower epithelial cell surfaces were detected in the patient's skin and serum. The patient's IgA autoantibodies labeled a recombinant desmosomal protein desmoglein 3 on immunoblotting and the immunolabeling of epithelial cell surfaces was eliminated by preadsorption with desmoglein 3. Thus, desmoglein 3 is identified as a target antigen in intraepidermal neutrophilic IgA dermatosis. The ability of IgA1 autoantibodies to bind neutrophils may be responsible for the prominent neutrophilic infiltration observed histopathologically and for the pustular lesions observed clinically.     

Method for measuring base/neutral and carbamate pesticides in personal dietary samples

Dietary uptake may be a significant pathway of exposure to contaminants. As such, dietary exposure assessments should be considered an important part of the total exposure assessment process. The objective of this work was to develop reliable methods that are applicable to a wide range of base/neutral and carbamate-type pesticides in duplicate diet samples collected as part of dietary exposure assessment studies. The resulting method needed to be sensitive to concentrations below 1 ng/g, accurate and precise, and as simple and cost effective as possible. As a first step, information was gathered on current methods for measuring pesticides in foods. Although the literature methods could serve as a starting point, few had been applied to duplicate diet samples and detection limits were generally high (10 to 100 ng/g). Experimental work was performed to evaluate individual extraction, cleanup, and analysis procedures; link the most promising procedures into analysis methods; and generate performance data on the final method. The final method used Soxhlet extraction with solvent partitioning and gel permeation chromatography cleanup. Gas chromatography/mass spectrometry was used for the analysis of base/neutral pesticides. High performance liquid chromatography analysis was used for the analysis of carbamate pesticides. Results of performance testing showed good accuracy (recovery > 70%), precision (% RSD < 25%), and sensitivity (method detection limits < 1.0 ng/g) for most pesticides targeted for study.