Attenuation of intracavitary applicators in 192Ir-HDR brachytherapy

Unlike the penetrating monoenergetic 662 keV gamma rays emitted by 137Cs LDR sources, the spectrum of 192Ir used in HDR brachytherapy contains low-energy components. Since these are selectively absorbed by the high-atomic number materials of which intracavitary applicators are made, the traditional neglect of applicator attenuation can lead to appreciable dose errors. We investigated the attenuation effects of a uterine applicator, and of a set of commonly used vaginal cylinders. The uterine applicator consists of a stainless steel source guide tube with a wall thickness of 0.5 mm and a density of 8.02 g/cm3, whereas the vaginal cylinders consist of the same stainless steel tube plus concentric polysulfone cylinders with a radius of 1 or 2 cm and a density of 1.40 g/cm3. Monte Carlo simulations were performed to compute dose distributions for a bare 192Ir-HDR source, and for the same source located within the applicators. Relative measurements of applicator attenuation using ion-chambers (0.125 cm3) confirmed the Monte Carlo results within 0.5%. We found that the neglect of the applicator attenuation overestimates the dose along the transverse plane by up to 3.5%. At oblique angles, the longer photon path within applicators worsens the error. We defined attenuation-corrected radial dose and anisotropy functions, and applied them to a treatment having multiple dwell positions inside a vaginal cylinder.     

Histopathological and ultrastructural alterations of induced Yersinia enterocolitica infection in mice

Yersinia enterocolitica is an enteric bacterium and infections by this organism are mostly foodborne. It has been implicated to cause enterocolitis, terminal ilitis. diarrhoea, mesenteric lymphadenitis and arthritis in man. Due to paucity of information regarding histopathological and specially ultrastructural alterations in tissues affected, this study was planned with mice as the experimental model. Nine pathogenic Y.enterocoliticaisolates were used to infect 80 albino mice by oral and intraperitoneal route. Pathological alterations were studied by light and electron microscopy. Histopathological examination of intestines showed severe edema, purulent enteritis, goblet cell hyperplasia infiltration of mononuclear cells, thickening of mucosa and necrosis of the tips of villi. Liver showed congestion, hepatocellular degeneration and necrosis, atrophy of hepatocytes and microabcesses. The lungs revealed congestion, edema, haemorrhage and purulent ronchopneumonia, while kidneys showed mild necrotic changes and bacterial emboli in glomeruli. Ultrastructural changes were indicative of mitochondrial degeneration and their loss in kidneys, membranous degeneration with formation of myelin figures in lungs and disorganization, disruption and bleb formation of microvilli in intestines. Y.enterocolitica caused significant histopathological and ultrastructural alterations in experimentally infected mice. Variation in pathogenicity of different strains of Y.enterocolitica was also observed.     

Leukocyte-reduced transfusions in cardiac surgery results of an implementation trial

An implementation trial of leukocyte-reduced transfusions in cardiac surgery (primary coronary artery bypass graft and valve replacement) was performed from July to December 1998; comparisons were made with data from the same period in 1997. Patients from both periods were similar in important preoperative and intraoperative variables (age, sex, weight, number of units of RBCs transfused, ejection fraction). The mean total number of complications was statistically significantly decreasedfrom 0.26 complications per patient in the non-leukocyte-reduced to 0.19 in the leukocyte-reduced recipients. Overall, the mean +/- ISD costs of care per patient decreasedfrom 1997 ($27,615 +/- $33,973) to 1998 ($27,038 +/- $24,107). Mean costs decreased $1,700 per patient for recipients of leukocyte-reduced blood in 1998 compared with recipients of non-leukocyte-reduced blood in 1997 Mean costs increased $4,000 per patient in patients who did not receive transfusions in 1998 compared with 1997. Hospitalization costs decreased when leukocyte-reduced transfusions were implemented for patients undergoing cardiac surgery in our institution. Implementation of leukocyte reduction may be cost neutral or cost saving in at least some settings.     

EGFR gene amplification in breast cancer: correlation with epidermal growth factor receptor mRNA and protein expression and HER-2 status and absence of EGFR-activating mutations.

The human epidermal growth factor receptor (HER) family of receptor tyrosine kinase has been extensively studied in breast cancer; however, systematic studies of EGFR gene amplification and protein overexpression in breast carcinoma are lacking. We studied EGFR gene amplification by chromogenic in situ hybridization (CISH) and protein expression by immunohistochemistry in 175 breast carcinomas, using tissue microarrays. Tumors with >5 EGFR gene copies per nucleus were interpreted as positive for gene amplification. Protein overexpression was scored according to standardized criteria originally developed for HER-2. EGFR mRNA levels, as measured by Affymetrix U133 Gene Chip microarray hybridization, were available in 63 of these tumors. HER-2 gene amplification by fluorescence in situ hybridization (FISH) and protein overexpression by immunohistochemistry were also studied. EGFR gene amplification (copy number range: 7-18; median: 12) was detected in 11/175 (6%) tumors, and protein overexpression was found in 13/175 (7%) tumors. Of the 11 tumors, 10 (91%) with gene amplification also showed EGFR protein overexpression (2+ or 3+ by immunohistochemistry). The EGFR mRNA level, based on Affymetrix U133 chip hybridization data, was increased relative to other breast cancer samples in three of the five tumors showing gene amplification. Exons 19 and 21 of EGFR, the sites of hotspot mutations in lung adenocarcinomas, were screened in the 11 EGFR-amplified tumors but no mutations were found. Three of these 11 tumors also showed HER-2 overexpression and gene amplification. Approximately 6% of breast carcinomas show EGFR amplification with EGFR protein overexpression and may be candidates for trials of EGFR-targeted antibodies or small inhibitory molecules.     

Spontaneous lymphocyte proliferation in human T-cell lymphotropic virus type I (HTLV-I) and HTLV-II infection: T-cell subset responses and their relationships to the presence of provirus and viral antigen production.

Spontaneous lymphocyte proliferation (SLP) during in vitro culture of mononuclear cells (MCs) characterizes over half of asymptomatic individuals infected with human T-cell lymphotropic virus type I (HTLV-I) or HTLV-II. Both CD4 and CD8 T-cell subsets within MC cultures are activated during SLP, as judged by high-density CD25 (CD25bright) expression; it is unclear, however, whether both cell subsets can directly undergo SLP. In the present investigation, the SLP capacities of purified CD8 and CD4 cells were examined in subjects infected with HTLV-I (n = 19) or HTLV-II (n = 54) in relation to the SLP status of MCs from each subject. No increase in SLP was observed for CD8 or CD4 cells from SLP-negative (SLP-) HTLV-infected subjects, whereas robust SLP characterized CD8 cells from all SLP-positive (SLP+) individuals, regardless of HTLV type. In contrast, SLP+ CD4 cells characterized only 23% (7 of 31) of HTLV-II+ SLP+ individuals, whereas SLP+ CD4 cells characterized 100% of HTLV-I+ SLP+ individuals. In cocultures of HTLV-II+ SLP+ CD8 cells and autologous SLP- CD4 cells, sizable proportions of both CD8 cells and CD4 cells coexpressed CD25bright, suggesting that SLP- CD4 cells were activated in the presence of SLP+ CD8 cells. PCR analysis for tax sequences detected provirus in most CD4- and CD8-cell preparations from HTLV-seropositive individuals, regardless of type and the SLP status of cell subsets. To determine whether SLP was associated with activation of viral genes, levels of HTLV-I and HTLV-II core antigen (Ag) in supernatants were measured. Viral Ag production and SLP responses were significantly correlated for both CD4 and CD8 cells in both HTLV-I and HTLV-II infections. However, inhibition of CD8- or CD4-cell SLP by cyclosporin A or anti-Tac (anti-CD25) did not reduce Ag production, indicating that Ag production is not coupled to SLP. These findings show that CD4 cells from SLP+ HTLV-I+ and SLP+ HTLV-II+ individuals differ in SLP capacity, that the absence of SLP does not indicate a lack of infection, and that production of viral Ag is associated with, but not dependent on, SLP.     

Genetic structure and affinity among eight ethnic populations of Eastern India: based on 22 polymorphic DNA loci.

The nature and extent of genetic variation at 22 polymorphic DNA loci, belonging to three distinct classes, especially, 12 STR loci (D3S1358, vWA, FGA, D5S818, D13S317, D7S820, D8S1179, D21S11, D18S51, HPRTB, F13B, LPL), four VNTR loci (D1S7, D4S139, D5S110, D17S79), and six coding loci (HLDQA1, LDLR, GYPA, HBGG, D7S8, GC) were investigated among eight population groups of West Bengal and Manipur regions of India. Of these, two groups from West Bengal belong to Caucasoid and six (one in WB and five in Manipur) belong to Mongoloid stock. Both STR and the expressed loci show wide diversity among the eight populations. For example, Manipur Muslims show differences in allele frequency when compared to four other regional populations. Similarly, Garo, one of the Mongoloid populations of West Bengal, differ in allele frequency from their counterparts in the Manipur region. Departure from Hardy-Weinberg expectations was observed at certain loci in a few populations (e.g., D21S1137 in Kayastha and Brahmin, HUM F13B in Meitei). Heterozygosity values were higher for Caucasoid than Mongoloid groups. The overall gene differentiation (GST) for STR loci is higher (5.3%) than for those at the expressed region (4.6%). The clustering pattern of the eight populations differs with respect to different classes of genetic markers used. The dendrograms based on six coding loci (HLDQA1, LDLR, GYPA, HBGG, D7S8, GC) differs from those based on STR and VNTR markers. Caucasoid and Mongoloid groups form different clusters and Manipur Muslims are distinct from others. The clustering pattern corresponded with the spatial and ethnic affiliations of the populations. Using different classes of DNA loci at the coding and noncoding region will help to better understand the influence of population structure variables on the genetic structure of populations.     

Detection of human T-lymphotropic virus (HTLV) tax sequences in New York City blood donors seronegative for HTLV types 1 and 2

A potential public health concern is the reported detection of the human T-lymphotropic virus (HTLV) tax gene in the lymphocytes of up to 11% of a low-risk group of New York City blood donors (NYBD). This study aimed to independently confirm the prevalence of HTLV tax sequences in 293 NYBD. All NYBD tested negative for antibodies to HTLV types 1 and 2 and HTLV Tax. HTLV tax sequences were not detected in the NYBD lymphocytes. These data demonstrate the lack of HTLV-1 tax in this group of NYBD at low risk for HTLV infection.     

Feasibility of using tissue microarrays for the assessment of HER-2 gene amplification by fluorescence in situ hybridization in breast carcinoma.

Tissue microarrays (TMAs) have been commonly used to study protein expression by immunohistochemistry (IHC). However, limited data exist on the validity of using TMAs to study gene amplification. In this study, we evaluated the feasibility of using breast carcinoma TMAs to study HER-2 gene amplification by fluorescence in situ hybridization (FISH). In addition, hormonal receptor status (ER and PR) and HER-2 protein overexpression by IHC were also studied, and results were compared with whole tissue sections. FISH for HER-2 was performed on formalin-fixed paraffin-embedded tissue from 114 invasive breast carcinomas both on whole tissue sections and on TMAs containing the same tumors. The TMA was created using 0.6-mm tissue cores with four sampled cores per tumor from the same tissue block used for whole section FISH. The PathVysion HER-2 probe kit was used for the FISH analysis. A ratio of HER-2:Chromosome17 > or =2.0 was interpreted as positive for gene amplification. The ER or PR was interpreted as positive when nuclear staining was detected in more than 10% of tumor cells. The HER-2 IHC (HercepTest; DAKO Corp, Carpinteria, CA) results were interpreted as 0, 1+, 2+, and 3+ according to standard criteria. The FISH results in the TMA and whole sections were concordant in 99 out of 101 successfully analyzed cases (99%). The FISH scores were consistent among the two to four cores in the majority of the cases. ER and PR results were concordant between whole sections and TMA cores in 97% (107/110) and 89% (97/109) cases, respectively. The overall concordance for HER-2 status by IHC between whole sections and TMA cores was 86% (94 out of 109 cases). TMAs are a reliable approach to study HER-2 gene amplification in a high throughput manner.     

Chromogenic in situ hybridization for the detection of HER-2/neu gene amplification in breast cancer with an emphasis on tumors with borderline and low-level amplification: does it measure up to fluorescence in situ hybridization?

We compared chromogenic in situ hybridization (CISH) with fluorescence in situ hybridization (FISH) for assessing HER-2/neu gene amplification using tissue microarrays (TMAs) made from formalin-fixed, paraffin-embedded tissue blocks from 113 cases of invasive breast carcinoma. TMAs were created using 0.6-mm tissue cores with 4 sampled cores per tumor. For both assays, a HER-2/chromosome 17 signal ratio of 2.0 or more was considered positive for gene amplification. The average ratio of cores from the same tumor was used for determination of gene amplification status of that particular tumor Of 113 cases, 102 were tested successfully by both assays. The results were concordant in 100.0% of cases (63 amplified; 39 nonamplified). All 22 cases of borderline (ratio, 2.0-2.5) or low-level (ratio, 2.6-3.9) amplification by FISH also showed HER-2 gene amplification by CISH. CISH is as sensitive as FISH in detecting borderline and low-level HER-2 amplification. Reliable recognition of the invasive carcinoma area by light microscopy and preservation of the test slides are added advantages of CISH. CISH performs as well as FISH in the analysis of HER-2 gene amplification in breast cancer and might have advantages in certain situations.