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Biomedical subjects

A H Lee

Publications and source records attributed to A H Lee.

At least 19 recordsLinked to original sources
PubMed1999

DNA inoculations with HIV-1 recombinant genomes that express cytokine genes enhance HIV-1 specific immune responses.

Vaccination with HIV-1 DNA sequences induce both humoral and cellular immune responses in experimental animals. However, these responses are relatively weak and are often only transient in their nature. In order to enhance the level of HIV-1 specific immunity, we have engineered HIV-1 DNA constructs which contained various cytokine genes such as interleukin-2 (IL-2), granulocyte-macrophage colony stimulating factor (GM-CSF) and interferon-gamma (IFN-gamma) gene. These constructs have deleted the tat and nmf genes of HIV-1 to eliminate their immunosuppressive effects. Immunizations with these recombinant constructs elicited moderate proliferative T cell responses but poor antibody responses in rats. However, inoculations of HIV-1 DNA that contained the GM-CSF or the IL-2 gene significantly enhanced humoral and proliferative T cell responses, respectively. Thus, recombinant HIV-1 genomes such as those described here may increase the efficacy of DNA vaccination.

AIDS Vaccines↗
PubMed1999

Angiogenesis and expression of thymidine phosphorylase by inflammatory and carcinoma cells in ductal carcinoma in situ of the breast.

Angiogenesis is essential for tumour growth and important in metastasis and for prognosis in invasive carcinoma of the breast. Two patterns of increased vascularity have been shown in mammary ductal carcinoma in situ (DCIS): a cuff of vessels close to the involved ducts, and vessels in the interductal stroma. Inflammation may potentially promote angiogenesis by release of angiogenic factors and digestive enzymes. A correlation has previously been found between the intensity of perivascular inflammation and stromal vascularity in DCIS, but no strong relationship has been observed between inflammation and angiogenesis in invasive carcinoma. Tumour angiogenesis is regulated by a number of angiogenic factors, including thymidine phosphorylase (platelet-derived endothelial cell growth factor), which is expressed at high levels in macrophages. Using immunohistochemical methods, thymidine phosphorylase expression and vascularity have been studied in DCIS (n = 34) and invasive carcinoma (n = 32). Stromal vascularity in DCIS was associated with thymidine phosphorylase expression in the perivascular inflammatory cells and in the cytoplasm of carcinoma cells. In invasive carcinoma, no relationship was found between vascularity and thymidine phosphorylase expression in either the carcinoma or the inflammatory cells. This study suggests that thymidine phosphorylase expression in both inflammatory and carcinoma cells may contribute to one of the patterns of vascularity in DCIS, but not in invasive disease.

Breast Neoplasms↗
PubMed1999

The value of central histopathological review of testicular tumours before treatment.

OBJECTIVE: To assess the value of central histopathological review of testicular tumours. MATERIALS AND METHODS: The histopathology reports of the referring hospital and central review were compared for all referred testicular specimens (201 orchidectomies and seven testicular biopsies) from 11 hospitals in one region, between 1992 and 1997. RESULTS: There were two main findings: First, there was a major discrepancy of tumour type in 12 specimens (6%). The most frequent change (in five cases) was from seminoma to nonseminomatous germ cell tumour (NSGCT). There were also difficulties with uncommon tumours such as spermatocytic seminoma, lymphoma and adenocarcinoma. Treatment was changed as result of the altered diagnosis in eight of these 12 patients. Second, there were discrepancies of interpretation of vascular invasion in 12 of 59 NSGCTs (20%). Differences of tumour elements recognized in NSGCTs were frequent. CONCLUSIONS: The errors discovered on central histopathological review of testicular tumours were significant, though small in number. This supports the idea of central review and is consistent with the specialization recommended in the Calman-Hine cancer arrangements.

Biopsy↗
PubMed1998

A discordancy test approach to identify outliers of length of hospital stay.

A discordancy test approach is proposed to identify outliers of inpatient length of stay. This has implications not only for benchmarking service delivery but also for linking budget allocation procedures to efficiency of health service provisions. The effects of shifting trim point thresholds on hospital payments are assessed in a case study of a group of obstetrical patients.

Adolescent↗
PubMed1998

Heterogeneity of intracellular pH and of mechanisms that regulate intracellular pH in populations of cultured cells.

Cells within solid tumors are known to exist in a microenvironment that may be acidic and depend on membrane-based mechanisms (Na+/H+ antiport and Na+-dependent Cl-/HCO3- exchanger) that regulate intracellular pH (pHi). We have used the fluorescent pH indicator 2',7'-bis-(2-carboxyethyl) 5 (and 6)-carboxyfluorescein and flow cytometry to study the distribution of pHi and the activity of these pHi-regulating mechanisms among populations of murine mammary sarcoma (EMT6), human breast cancer (MCF-7), and Chinese hamster ovary cells exposed to different levels of extracellular pH (pHe). Cells were exposed to Na+ buffer in the presence or absence of HCO3- and of 5-(N-ethyl-N-isopropyl)-amiloride (a potent inhibitor of the Na+/H+ antiport) to determine the relative importance of each exchanger in the regulation of pHi. Our results indicate that: (a) the distribution of pHi at any value of pHe is broader than can be accounted for by machine noise; (b) cells maintain levels of pHi that are higher than pHe under acidic conditions; (c) the distribution of pHi is narrower when the Na+-dependent Cl-/HCO3- exchanger is active; and (d) populations that are derived from selected cells with values of pHi at lower and higher ends of the pHi distribution generate pHi distributions that are similar to those of controls, suggesting a stochastic variation in the activity of membrane-based mechanisms that regulate pHi. Our data suggest that the Na+-dependent Cl-/HCO3- exchanger is the dominant mechanism for regulation of pHi under moderately acidic conditions such as may occur in the microenvironment of solid tumors.

Amiloride↗
PubMed1998

Cyclin D1 and associated proteins in mammary ductal carcinoma in situ and atypical ductal hyperplasia.

Experimental studies suggest that cyclin D1 is a potential oncogene but in clinical studies of invasive breast cancer, overexpression of cyclin D1 is found to be associated with oestrogen receptor (ER) expression and low histological grade, both markers of good prognosis. Immunohistochemistry has been used to examine the relationship between cyclin D1 expression and differentiation in 36 cases of ductal carcinoma in situ (DCIS) and the interrelationship between expression of cyclin D1, its associated protein product of the retinoblastoma gene (pRb), and ER, in this group of cases. The expression of these markers has also been examined in nine cases of atypical ductal hyperplasia (ADH) and these results have been compared with the levels of expression seen in DCIS. Cyclin D1 overexpression was found in 23/36 (64 per cent) cases of DCIS and, in contrast to invasive carcinoma, there was no relationship with either differentiation or ER expression. The level of pRb expression was significantly associated with cyclin D1 expression (rS = 0.49, P = 0.001) and only two cases (6 per cent) were pRb-negative. There was no association between pRb and differentiation of DCIS or ER status. In contrast to DCIS, only one case of ADH showed overexpression of cyclin D1 (Mann-Whitney U-test, P = 0.02). All cases of ADH were ER-positive and showed moderate pRb staining, similar to that seen in well-differentiated DCIS. These results provide further evidence that overexpression of cyclin D1 plays a role early in carcinogenesis.

Adult↗
PubMed1998

Invasive lobular and invasive ductal carcinoma of the breast show distinct patterns of vascular endothelial growth factor expression and angiogenesis.

Angiogenesis is essential for tumour growth and important in tumour metastasis and prognosis. Vascular endothelial growth factor (VEGF) stimulates endothelial proliferation in vitro and angiogenesis in vivo. VEGF expression has been correlated with high vascularity in tumours, including carcinoma of the breast. This study investigated VEGF expression and vascularity of invasive lobular (n = 10) and invasive ductal carcinoma (n = 28), and pure ductal carcinoma in situ of the breast (n = 33). VEGF protein expression was studied with immunohistochemistry and VEGF mRNA with in situ hybridization. Vascular density was assessed on sections stained for von Willebrand factor. There was more expression of both VEGF protein (P = 0.006) and mRNA (P = 0.002) in invasive ductal than in invasive lobular carcinoma. VEGF protein (rs = 0.32, P = 0.047) and mRNA (rs = 0.56, P = 0.04) correlated with vascular density in invasive ductal carcinoma. In invasive lobular carcinoma, vascular density did not correlate with VEGF mRNA (rs = 0.15, P = 0.35) and was inversely related to VEGF protein (rs = -0.57, P = 0.04). There were no significant differences in vascular density between the two types of invasive carcinoma, suggesting that VEGF is important in angiogenesis in invasive ductal carcinoma, but that other angiogenic factors are important in invasive lobular carcinoma. Although VEGF protein was frequently expressed in ductal carcinoma in situ, no relationship was found between VEGF and the two patterns of angiogenesis previously described.

Breast↗
PubMed1998

Vascular density does not predict future metastatic disease in clinical stage 1 non-seminomatous germ cell tumours of the testis.

AIM: This study aimed to determine whether patients with stage 1 testicular non seminomatous germ cell tumours (NSGCT) with high vascular density have a greater risk of disease recurrence than those with a low vascular density. METHODS AND RESULTS: Orchidectomy specimens from 42 patients with stage 1 NSGCT, treated by orchidectomy and surveillance alone, were studied. Vessel density was counted in tumour sections immunohistochemically stained for CD34. The mean of the three highest counts (x250, field size 0.67 mm2) for each tumour was used. Tumour vessel density was very similar for relapsing and non relapsing patients. Vascular invasion was the only variable significantly predictive of disease recurrence at 2 years post-orchidectomy (P = 0.025). There was wide variation of vessel counts between different blocks of a tumour, compared with interobserver variation. The tumour tissue type in the area of highest vessel density was embryonal carcinoma in 50% and teratoma (mature or immature) in 38%. CONCLUSIONS: We confirmed the value of vascular invasion as a prognostic marker in stage 1 NSGCT. Tumour vessel density was of no prognostic value. Two factors may contribute to this. First, there was wide variation of vessel density between different blocks of a tumour. Second, the most vascular area in a tumour was frequently in low-grade tumour.

Adolescent↗
PubMed1998

Post-mortem examination after cardiac surgery.

Following a recent enquiry into surgery at a paediatric cardiac centre in England, there will be substantial changes in the way that the success and failure of surgical procedures will be monitored and investigated. Post-mortem examinations on patients dying after cardiac surgery are likely to be performed and reported in more detail. This review describes the protocol that we have developed and summarizes recent clinical and pathological studies that have increased our understanding of postoperative pathophysiology. Close attention should be paid to the history, particularly the operation note. Cardiac failure is the commonest cause of death. We believe this is a clinicopathological diagnosis and provide definitions of preoperative and perioperative cardiac failure. Haemorrhage, stroke, pulmonary emboli and infection are other important causes of death. Methods of dissection are suggested for bypass grafts and valve replacements. Two recent studies show that the post-mortem examination provides answers to most clinical questions and reveals an unexpected cause of death in 10-15% of patients. There are limitations however: an incomplete or indeterminate cause of death is found in 14-25% of patients, most commonly sudden clinically unexplained death or clinically unexplained cardiac failure soon after surgery.

Autopsy↗
PubMed1998

Sensitivity of parametric link functions in generalized linear models.

A common method of choosing the link function in generalized linear models is to specify a parametric link family indexed by unknown parameters. The maximum likelihood estimates of such link parameters, however, may often depend on one or several extreme observations. Diagnostics are derived to assess the sensitivity of the parametric link analysis. Two examples demonstrate that the proposed diagnostics can identify jointly influential observations on the link even when masking is present.

Blood Sedimentation↗
PubMed1997

Comparison of various expression plasmids for the induction of immune response by DNA immunization.

Intramuscular injection of plasmid DNA is an efficient method to introduce a foreign gene into a live animal. We investigated several factors affecting the gene transfer efficiency and the following immune response by intramuscular injection of plasmid DNA. When the strength of several highly efficient viral promoters was compared in muscle by using the chloramphenicol acetyltransferase (CAT) gene as an indicator, cytomegalovirus (CMV) immediate early promoter was found to be stronger than any other viral promoters including Rous sarcoma virus (RSV), murine leukemia virus (SL3-3) and simian virus 40 (SV40) early promoters. Inclusion of adenovirus tripartite leader (TPL) sequences and a synthetic intron in the 5' untranslated region of mRNA moderately stimulated the CAT expression. On the other hand, the expression of encephalomyocarditis virus (EMCV) VP1 gene was greatly enhanced by the TPL sequences and an intron. The level of humoral immune response by intramuscular injection of various VP1 expression plasmids was compared. The seroconversion rate was highly dependent on the strength of the expression vector. However, the ratio of IgG1 and IgG2a immune response was not significantly variable depending on the strength of the expression vector. Also, the efficiency of the sindbis virus-based DNA vector was examined for the gene expression and immune response. Although a high level of CAT expression was obtained in muscle by using this system, VP1 was not produced as much as the conventional expression vectors. Furthermore, little humoral immune response was elicited by intramuscular injection of VP1-expressing sindbis vector, suggesting that this system was not superior to the conventional vector for DNA immunization.

Animals↗
PubMed1997

Generation of the replication-competent human immunodeficiency virus type 1 which expresses a jellyfish green fluorescent protein.

The gene encoding a red-shifted green fluorescent protein variant (EGFP) was introduced into a human immunodeficiency virus type 1 (HIV-1) molecular clone by replacing the nef gene. The EGFP-expressing HIV-1 replicated efficiently in established human T cells. The expression of EGFP in the virus-infected cells was confirmed by fluorescence microscopy and also by Western blot analysis using the GFP antibodies. The EGFP gene was stably maintained in the viral genome during prolonged passages. EGFP-expressing HIV-1 could be used for anti-HIV-1 drug screening, sorting of virus-infected cells by fluorescence activated cell sorting (FACS) analysis, and for the rapid and simple detection of virus-infected cells by fluorescence microscopy.

Animals↗
PubMed1997

Angiogenesis and inflammation in ductal carcinoma in situ of the breast.

Several recent studies suggest that vascular density may be an independent prognostic indicator in invasive carcinoma of the breast. Increased vascularity has also been shown in ductal carcinoma in situ (DCIS). The prognostic significance of the inflammatory infiltrate in mammary carcinoma is more controversial, but it could affect angiogenesis by releasing angiogenic factors and digesting matrix. Vascularity and inflammation have been studied in 41 examples of pure DCIS, classified using the method of Holland et al. Immunohistochemistry was performed with antibodies to von Willebrand factor, CD3, CD8, CD45RO, CD45RA, CD20, CD68, and c-erB-2. The main pattern of inflammation was clusters of B and T cells situated either adjacent to involved ducts or in the interductal stroma. Typically, these clusters were around vessels with plump endothelium suggestive of high endothelial venules. A less prominent pattern was a diffuse stromal infiltrate of macrophages and T cells. There were two patterns of increased vascularity associated with DCIS: necklaces of vessels close to the involved ducts and vessels arranged diffusely in the interductal stroma. Each pattern of inflammation and of vascularity was graded semi-quantitatively. Increased stromal vascularity was associated with the perivascular clusters of inflammation; both were associated with c-erB-2 expression and extent of the DCIS. Necklaces of vessels were associated with the diffuse inflammation. Perivascular inflammation and c-erB-2 (but neither pattern of vascularity) were associated with poor differentiation of the DCIS. Thus, different patterns of inflammation are associated with different patterns of vessels. The clusters of B and T cells may be recruited via high endothelial venules induced by the DCIS. Cytokines released by the DCIS and/or the inflammatory cells (clusters or diffuse) may stimulate the two patterns of new vessel formation.

Adult↗
PubMed1997

Protective immunity against heterologous challenge with encephalomyocarditis virus by VP1 DNA vaccination: effect of coinjection with a granulocyte-macrophage colony stimulating factor gene.

For DNA vaccination studies, recombinant VP1 protein of encephalomyocarditis virus (EMCV) was produced from Escherichia coli, and eukaryotic VP1 expression vector, pCT-Gs-VP1, was generated and used as a DNA vaccine. Mice were immunized intramuscularly (i.m.) with pCT-Gs-VP1 in the presence or absence of plasmid DNA expressing granulocyte-macrophage colony stimulating factor (GM-CSF), and were subsequently analyzed for their anti-VP1 immune responses with recombinant VP1 in ELISA. Immunization of mice with pCT-Gs-VP1 resulted in VP1-specific immune response and 43% protection from subsequent lethal heterologous challenge of EMCV. Coinjection of mice with pCT-Gs-VP1 and plasmid DNA encoding GM-CSF was shown to increase the seroconversion rate of the immunized mice with a single DNA injection, and enhanced to a higher degree VP1-specific immunity, which appeared to result in better protection (about 80%) from lethal virus challenge. Thus, our results provide evidence for the potential use of GM-CSF to induce better immune response and resistance against viral infection in DNA vaccination.

Animals↗
PubMed1997

Prospective study of the value of necropsy examination in early death after cardiac surgery.

OBJECTIVE: To assess the value of necropsy examination in patients dying soon after cardiac surgery, particularly the proportion of clinical questions answered by the necropsy, the frequency of major unexpected findings, and the limitations of the procedure. DESIGN: A three year prospective study of necropsy examinations in adult patients dying before discharge or within 30 days of cardiac surgery performed under cardiopulmonary bypass in one hospital. SETTING: Tertiary referral centre. RESULTS: 123 of 2781 patients (4.4%) died in the early postoperative period, and necropsy examination was performed in 108 of these (88%). The mortality after emergency procedures (18%) was much higher than after routine operations (2.6%). The main causes of death were cardiac failure (52%), haemorrhage (14%), cerebral disease (6%), and pulmonary emboli (5%). The necropsy changed the stated cause of death in 16 patients (15%), and answered clinical questions in 24 of 38 patients. In 15 patients necropsy examination did not provide a full explanation of death. Most of these patients died of cardiac failure soon after surgery or were sudden unexpected deaths. CONCLUSIONS: Necropsy examination in patients dying early after cardiac surgery is valuable as it answers the majority of clinical questions, and shows unexpected findings in a significant proportion of cases.

Adult↗
PubMed1997

Angiogenesis and inflammation in invasive carcinoma of the breast.

AIM: To investigate the relation between angiogenesis and inflammation in invasive carcinoma of the breast. METHODS: Sections from 75 invasive carcinomas of the breast were stained using immunohistochemistry for von Willebrand factor, CD3, CD8, CD45RO, CD45RA, CD20, CD68, and c-erbB-2. Tumour vascularity was assessed by counting vessels in the three most vascular areas, and calculating the average (x 400 magnification, field 0.168 mm2). Each pattern of inflammation was scored semiquantitatively. RESULTS: The main pattern of inflammation was a diffuse infiltrate of macrophages, and to a lesser extent T cells. Perivascular and perilobular clusters of B and T cells were noted at the edge of the carcinomas, but were less prominent than the diffuse inflammation. Diffuse inflammation, particularly macrophages, was associated with high tumour grade, tumour necrosis, large tumour size, and c-erbB-2 expression. Perivascular and perilobular inflammation also increased with tumour grade. Tumour vascularity increased slightly with intensity of diffuse inflammation (Spearman's rank correlation coefficient rs = 0.17, p = 0.08), and was inversely related to perilobular inflammation (rs = -0.23, p = 0.03). CONCLUSIONS: The correlations between inflammation and vascularity were weak in this study (r2 about 0.04) and thus there was no evidence of an important relation. Discrepancies between this and other studies may be resolved by studying expression of angiogenic cytokines and proteolytic enzymes by tumour infiltrating inflammatory cells, and their relation to tumour vascularity.

Breast Neoplasms↗
PubMed1996

Inflammatory infiltrate in invasive lobular and ductal carcinoma of the breast.

The significance of inflammation in carcinoma of the breast is controversial. Little attention has been paid to different patterns of inflammation or inflammation associated with different histological types of carcinoma. We have looked at the pattern of inflammation in 123 invasive mammary carcinomas (including 46 lobular), and characterised the inflammatory cells with immunohistochemistry in 21. We found different patterns of inflammation in ductal and lobular carcinoma. Diffuse inflammation was seen more in ductal carcinoma, particularly of high grade, and was predominantly composed of macrophages and T cells. It was associated with necrosis, but the correlation was weak, suggesting that other factors are important. Perilobular inflammation was seen most frequently in lobular and high-grade ductal carcinomas, particularly at the tumour edge. Perivascular inflammation was also largely at the tumour edge, but was not more common in any tumour type. In contrast to the diffuse inflammation, the perivascular and perilobular inflammation was composed of T and B cells. Normal lobules at the tumour edge showed consistent expression of HLA-DR, whereas lobules away from the tumour were negative. A combination of perilobular and perivascular inflammation composed of B and T cells with epithelial expression of HLA-DR mimicking lymphocytic lobulitis was seen more frequently in lobular than ductal carcinoma.

Adult↗