Search PubMed⌕ Search

Biomedical subjects

J Boyd

Publications and source records attributed to J Boyd.

At least 109 records · Page 6Linked to original sources
PubMed1996

Increased food intake and body weight gain after lateral hypothalamic dopaminergic cell implantation.

To examine our hypothesis that dopamine activity in the lateral hypothalamic area (LHA) may play a role in enhancing the process of eating, a fetal cell suspension of predominantly dopaminergic cells was bilaterally transplanted into the LHA of study rats via direct injection; controls had carrier medium injection. Thereafter, mean daily food intake was 1 g per day greater in dopaminergic cell transplanted rats vs. controls for each day of the 10-week observation period. This resulted in a significantly greater cumulative body weight gain in study rats vs. controls (386 +/- 5.1 g vs. 354 +/- 3.8 g, respectively). On sacrifice at the end of the study, transplanted cells in the LHA were viable. Our data suggest that bilateral LHA dopaminergic cell transplant which presumably resulted in chronically and persistently enhanced dopaminergic activity in the LHA is associated with overeating and consequently, an excess weight gain.

Animals↗
PubMed1996

Mutational analysis of the p21/WAF1/CIP1/SDI1 coding region in human tumor cell lines.

p21/WAF1/CIP1/SDI1 is an important cell-cycle mediator with tumor suppressor gene capabilities, and its inactivation could potentially lead to tumor progression. Because tumor suppressor genes are commonly inactivated by somatic and germline mutations, we analyzed a variety of human tumor cell lines for p21 mutations. We used single-strand conformational analysis and direct sequencing to identify possible mutations in the p21 coding region. Two base-alterations were observed in 41 immortalized human tumor cell lines. A previously reported polymorphism that results in a serine-to-arginine amino-acid substitution at codon 31 was found in 24% (10 of 41) of the tumor cell lines but was also found in 10% (six of 62) of normal parental DNAs tested and 7% (three of 43) of normal DNAs from patients with primary endometrial tumors. Another nucleotide substitution found at codon 80 resulted in the replacement of threonine with methionine. Codon 80 changes were found in 7% (three of 41) of the tumor cell lines (all endometrial) and in 2% (one of 62) of the normal parental DNAs. This change was not found in any of the primary endometrial tumors examined. The biological activity of these base changes was analyzed by using in vitro cyclin-dependent kinase 2-cyclin A kinase assays and calcium phosphate transfections. We observed that wild-type p21 and the p21 variants had similar growth-inhibitory abilities. Thus, our results suggest that mutation of the p21 gene is not prevalent in human tumor cell lines and is not a probable mechanism of inactivation of this gene.

Base Sequence↗
PubMed1996

p53 protein expression and gene analysis in clear cell adenocarcinoma of the vagina and cervix.

OBJECTIVE: p53 is the most commonly mutated gene in human cancers. The objective of this study was to determine if clear cell adenocarcinomas (CCAs) of the vagina and cervix are associated with p53 gene mutations or alterations in p53 tumor-suppressor protein expression. METHODS: Paraffin-embedded tissue specimens from 21 women (median age 22 years) with clear cell adenocarcinoma of the vagina or cervix were studied. Fifteen women had a prior history of in utero exposure to diethylstilbestrol. p53 protein expression was detected by immunohistochemical (IHC) analysis with monoclonal antibody DO-7 (Dako Corp.) which recognizes both wild-type and mutant p53 proteins. For p53 gene analysis, genomic DNA from malignant tissue was isolated and exons 4-10 were amplified by PCR and subjected to mutation screening by single-stranded conformation polymorphism (SSCP) analysis. RESULTS: p53 protein was detected by IHC in tumors from 14 of 21 cases (67%). The observed p53 staining patterns were heterogeneous in both the proportion and intensity of tumor cells stained but were clearly overexpressed relative to the surrounding benign stroma. Metastatic tumors from 3 women with metastatic disease were also positive for p53 staining. SSCP analysis did not identify p53 mutations in any of the cases and strongly suggests that the tumors contained only wild-type p53 alleles. CONCLUSIONS: Recent studies have demonstrated that wild-type p53 may accumulate in response to DNA damage which normally leads to growth arrest or programmed cell death. Our observations are consistent with the hypothesis that p53 overexpression in CCAs of the vagina and cervix is a response to generalized DNA damage, rather than a result of p53 protein half-life prolongation resulting from mutational inactivation of p53. Overexpression of wild-type p53 protein in vaginal and cervical CCA may relate to the more favorable prognosis of this subset of tumors in comparison to other gynecologic tumors containing mutated p53 genes.

Adenocarcinoma, Clear Cell↗
PubMed1996

Adenovirus-mediated gene therapy of ovarian cancer in a mouse model.

OBJECTIVE: Our purpose was to test the feasibility of adenovirus-mediated gene therapy of ovarian cancer. STUDY DESIGN: Ovarian cancer cell lines were exposed to an adenovirus vector expressing a reporter gene (lacZ) and to the same vector bearing the herpes simplex virus thymidine kinase gene (Ad.RSVtk) followed by ganciclovir. lacZ expression and growth inhibition were quantitated. Immunodeficient mice were injected intraperitoneally and subcutaneously with human ovarian cancer cells and treated with Ad.RSVtk and ganciclovir. Statistical analyses included one-way analysis of variance and t tests. RESULTS: Staining for lacZ demonstrated viral transduction in vitro. After exposure to Ad.RSVtk all cell lines showed significant (p < 0.0001, analysis of variance) cytotoxicity to ganciclovir. Human ovarian tumor cells established subcutaneously or intraperitoneally in immunodeficient mice responded to therapy with Ad.RSVtk followed by ganciclovir. Treated mice had a 10- to 20-fold lower subcutaneous tumor burden than did control mice. Additionally, no intraperitoneal tumors were observed in treated mice. CONCLUSIONS: Ovarian cancer cells are readily transduced with recombinant adenovirus and become sensitive to ganciclovir after transduction with Ad.RSVtk. These data support the development of this method for human clinical trials.

Adenoviridae↗
PubMed1996

Expression and mutational analysis of P53 in stage IB and IIA cervical cancers.

OBJECTIVE: This study evaluates overexpression of the p53 protein and point mutation in the P53 gene in a group of patients with stage IB and IIA cervical cancer. STUDY DESIGN: We reviewed the medical records of all patients who underwent radical hysterectomy for the treatment of stage IB and IIA cervical cancer between 1980 and 1985 at Memorial Sloan-Kettering Cancer Center. Overexpression of p53 protein was determined with the use of immunohistochemistry on fixed and paraffin-embedded tissue. Two blocks were selected for each tumor, and tissue sections from each block were tested with both monoclonal (Ab-6) and polyclonal (CM-1) anti-p53 antibodies. Molecular analysis for determination of specific P53 gene mutations was performed with single-strand conformation polymorphism analysis. A group of 132 patients was identified for inclusion in the study. RESULTS: Fifty-eight of 132 tumors (44%) showed overexpression of the p53 protein and were subjected to molecular analysis. Discrepancy between pairs of blocks (7/132, 5.3%) and between antibodies for the same block (5/264, 1.9%) was uncommon. High-level overexpression was rare (5/132, 3.8%). No difference in survival was found on the basis of overexpression of p53 protein. Only one of the 58 cases (1/58, 1.7%) that showed overexpression of the p53 protein exhibited a point mutation (exon 8) in P53 by single-strand conformation polymorphism. This case had a low level of overexpression of p53 protein on immunohistochemistry. CONCLUSIONS: Low levels of overexpression of p53 were frequently seen in early cervical cancers (40/132, 30%). However, mutation of the P53 gene was rarely seen in these tumors. Overexpression of p53 protein as detected by immunohistochemistry is not predictive of a somatic mutation in the P53 gene in cervical cancer. Molecular analysis is required for confirmation of P53 mutations in these tumors.

Female↗
PubMed1996

Mutation of MSH3 in endometrial cancer and evidence for its functional role in heteroduplex repair.

Many human tumours have length alterations in repetitive sequence elements. Although this microsatellite instability has been attributed to mutations in four DNA mismatch repair genes in hereditary nonpolyposis colorectal cancer (HNPCC) kindreds, many sporadic tumours exhibit instability but no detectable mutations in these genes. It is therefore of interest to identify other genes that contribute to this instability. In yeast, mutations in several genes, including RTH and MSH3, cause microsatellite instability. Thus, we screened 16 endometrial carcinomas with microsatellite instability for alterations in FEN1 (the human homolog of RTH) and in MSH3 (refs 12-14). Although we found no FEN1 mutations, a frameshift mutation in MSH3 was observed in an endometrial carcinoma and in an endometrial carcinoma cell line. Extracts of the cell line were deficient in repair of DNA substrates containing mismatches or extra nucleotides. Introducing chromosome 5, encoding the MSH3 gene, into the mutant cell line increased the stability of some but not all microsatellites. Extracts of these cells repaired certain substrates containing extra nucleotides, but were deficient in repair of those containing mismatches or other extra nucleotides. A subsequent search revealed a second gene mutation in HHUA cells, a missense mutation in the MSH6 gene. Together the data suggest that the MSH3 gene encodes a product that functions in repair of some but not all pre-mutational intermediates, its mutation in tumours can result in genomic instability and, as in yeast, MSH3 and MSH6 are partially redundant for mismatch repair.

Base Sequence↗
PubMed1996

Unusual alpha-adrenoceptor subtype in canine saphenous vein: comparison to mesenteric vein.

1. We investigated the nature of the adrenoceptors in the dog saphenous vein (DSV) and dog mesenteric vein (DMV) to determine the nature of the unexpected interactions of phenylephrine and methoxamine with rauwolscine in the DSV, i.e. the ability of the putative alpha 2-adrenoceptor antagonist to inhibit competitively contractions to these alpha 1-agonists. Radioligand binding studies were performed in parallel with contractility studies. 2. Functionally, in the DSV, phenylephrine and methoxamine-induced, contractions were antagonized by rauwolscine with Schild slopes of -0.52 and -0.46, respectively and apparent pA2 values of 8.5 and 9.2, respectively. Such antagonism was not observed in the DMV. In the DSV, prazosin competes for [3H]-rauwolscine binding sites with a high and a low affinity binding site (Ki of 1.49 +/- 0.65 and 94.7 +/- 51 microM, n = 6, respectively). 3. Pretreatment with 100 microM chloroethylclonidine (CEC) for 15 min abolished [3H]-prazosin binding in microsomes from both veins and reduced binding (Bmax) of [3H]-rauwolscine in microsomes by 55.1 +/- 0.8% (n = 3) in the DSV but did not affect the Bmax in the DMV. CEC pretreatment in the venular rings denuded of endothelium caused persistent contraction in the DSV but not in the DMV. In the DSV, CEC appeared to interact with a single [3H]-rauwolscine binding site. In both the DSV and the DMV, CEC (100 microM) caused a significant shift in the EC50 values for phenylephrine and methoxamine. Maximum responses in the DMV were significantly attenuated while those in the DSV were unaffected when total tension was considered. 4. Studies of the functional interactions of the DSV and the DMV with WB 4101 or 5-methylurapidil (5-MU) suggested the presence of alpha 1D-adrenoceptors in the DSV and alpha 1A-adrenoceptors in the DMV. The receptors inactivated by CEC in the DMV and DSV may represent some or all of the receptors with properties of alpha 1D and alpha 1A-receptors present in the two veins. Studies of radioligand binding interactions of these two antagonists with [3H]-prazosin, were consistent with the presence of some alpha 1D-receptors in DSV and alpha 1A-receptors in DMV. These findings raise questions about the selectivity of CEC in differentiating alpha 1-adrenoceptor subtypes. 5. B-HT 920 caused contractions in the DSV smaller than those to the alpha 1-agonists but the maximum was not affected by CEC pretreatment. The EC50 values were shifted to the left after CEC. In radioligand binding studies, B-HT 920 competition for [3H]-rauwolscine binding was not significantly affected by CEC pretreatment. 6. These results suggest the presence of unusual alpha-adrenoceptors in the DSV. In addition to alpha 2-adrenoceptors, receptors recognizing rauwolscine as well as prazosin, WB 4101, phenylephrine and methoxamine and susceptible to inactivation by CEC are present. They appear to be, in part, unusual alpha 1D-adrenoceptors.

Adrenergic alpha-Agonists↗
PubMed1996

Measuring outcomes: one month survival after acute myocardial infarction in Scotland.

OBJECTIVE: To examine 30 day survival after acute myocardial infarction as an outcome indicator, and explore the effects of adjusting for available prognostic factors such as age, sex, co-morbidity, deprivation, and deaths outside hospital. DESIGN: Cohort study. SETTING: The Scottish Record Linkage System was analysed. This national data-base links inpatient data to death certificate information for a population of 5.1 million. SUBJECTS: All 40,371 admissions to hospital with a principal diagnosis of acute myocardial infarction, plus all 18,452 deaths outside hospital with a principal cause of death registered as acute myocardial infarction (ICD9 code 410) during 1988-1991. MAIN OUTCOME MEASURES: The outcome event was death from any cause, within hospital or elsewhere, within 30 days of admission. RESULTS: During 1988-1991, 30 day survival after acute myocardial infarction was 77% in 40,371 hospital admissions, but only 53% when 18,452 acute myocardial infarction deaths in the community were included (a population-based outcome indicator with many advantages). Using logistic regression at an individual patient level, the odds of dying within 30 days effectively doubled for each decade of age (odds ratio compared with patients aged under 55: 2.3 aged 55-64, 4.4 aged 65-74, 8.2 aged 75-84, 12.0 aged 85 plus); were marginally higher in females than in males (odds ratio 1.07); were almost doubled in patients with a history of previous infarction, coronary heart disease, or other heart disease, and were also significantly increased in patients with circulatory disease, respiratory disease, neoplasm, or diabetes. Socioeconomic deprivation had no significant effect. Marked variations in survival between different hospitals and health board areas persisted, even after adjusting for the above prognostic factors. CONCLUSION: One month survival after acute myocardial infarction could be a useful means of measuring outcome of hospital care. There was important geographical variation in one month survival. These differences could be accounted for by variations in referral, admission, diagnosis, definition, and coding. These variables merit further research and local clinical audit before one month survival after acute myocardial infarction can be reliably used for detecting differences in quality of care. In addition, it would be essential to take account of infarct severity.

Age Factors↗
PubMed1996

The next chapter.

Explore the source record for details and available documents.

Administrative Personnel↗
PubMed1995

Regulation of microfilament organization and anchorage-independent growth by tropomyosin 1.

Variants of chemically immortalized Syrian hamster embryo cells that had either retained (supB+) or lost (supB-) the ability to suppress tumorigenicity when hybridized with a fibrosarcoma cell line were subcloned. Both supB cell types are nontumorigenic; however, the supB- but not supB+ cells exhibit conditional anchorage-independent growth. Alterations of actin microfilament organization were observed in supB- but not supB+ cells that corresponded to a significant reduction of the actin-binding protein tropomyosin 1 (TM-1) in subB- cells. To examine the possibility of a direct relationship between TM-1 expression and the subB- phenotype, subB+ cells were transfected with an expression vector containing the TM-1 cDNA in an antisense orientation. The antisense-induced reduction of TM-1 levels in supB+ clones caused a microfilament reorganization and conferred anchorage-independent growth potential that were indistinguishable from those characteristic of supB- cells. These data provide direct evidence that TM-1 regulates both microfilament organization and anchorage-independent growth and suggest that microfilament alterations are sufficient for anchorage-independent growth.

Actin Cytoskeleton↗
PubMed1995

Molecular basis of endometrial cancer.

BACKGROUND: Most human cancers are thought to arise from alterations in oncogenes and tumor suppressor genes. METHODS: Molecular techniques have been used to identify specific genetic alterations in endometrial cancers. RESULTS: Overexpression of the HER-2/neu oncogene occurs in 10% of endometrial cancers and correlates with poor survival. Alterations in other receptor tyrosine kinases (c-fms and epidermal growth factor receptor) also occur in some cases. The c-myc oncogene, which encodes a nuclear transcription factor, also may be overexpressed in some invasive cancers. Mutations in the K-ras oncogene occur in 10% and in 20-30% of American and Japanese endometrial cancers, respectively. K-ras mutations also have been observed in endometrial hyperplasias, and this may represent an early event in the development of some cancers. Mutation of the p53 tumor suppressor gene, with resultant overexpression of mutant p53 protein, occurs in 20% of endometrial adenocarcinomas. Overexpression of p53 is associated with advanced stage and poor survival. Because p53 mutations do not occur frequently in endometrial hyperplasias, this may be a relatively late event in endometrial carcinogenesis. Recent studies have shown that mutations occur in microsatellite sequences in some endometrial cancers. Because microsatellite instability in hereditary nonpolyposis colon cancer has been found to be caused by mutations in DNA repair genes, similar mutations are being sought in endometrial cancers. CONCLUSIONS: Although several molecular alterations have been identified, the molecular pathogenesis of endometrial cancer remains poorly understood.

Amidohydrolases↗
PubMed1995

Expression and mutation analysis of the p53 gene in uterine papillary serous carcinoma.

BACKGROUND: The status of p53 protein expression was determined by immunohistochemistry and correlated with genetic analysis and clinical outcome in patients with uterine papillary serous carcinoma (UPSC). METHODS: Twenty-two patients with UPSC were identified and immunohistochemical staining of p53 protein was performed. Staining was analyzed by quantitating nuclear reactivity in 500 randomly counted cells per specimen. DNA analysis was performed on the tumors using single-strand conformation polymorphism (SSCP) analysis of exons 4-10 of the p53 gene, followed by DNA sequencing of all variants. Clinical data and patient status were ascertained from chart reviews. RESULTS: Sixteen of the 22 (73%) tumors were scored as p53-overexpressing as determined by immunohistochemical analysis. Patients whose tumors overexpressed p53 had a statistically significant shorter survival than those whose tumors did not (P < 0.022). DNA analysis of the 22 tumors revealed five with mutations of the p53 gene. Only three of these mutations were observed in tumors that overexpressed p53. CONCLUSIONS: A relatively large percentage of UPSC tumors exhibited high p53 immunoreactivity. Overexpression is correlated with poor prognosis. Positive immunohistochemistry for p53 protein in UPSC is not necessarily indicative of a genetic mutation.

Aged↗
PubMed1995

Prevalence of androgen receptor gene mutations in latent prostatic carcinomas from Japanese men.

The incidence rate of clinically apparent prostatic carcinoma is 8-fold higher in the United States than in Japan, while the prevalence of latent prostatic carcinoma, a presumed precursor to clinical carcinoma, is similar in the two countries. The purpose of this study was to investigate the hypothesis that this profound difference in incidence rates of clinical carcinoma reflects distinct profiles of molecular genetic alterations in the latent precursor lesions that occur in the two countries. A significant fraction of latent carcinomas from Japanese men were found to contain inactivating mutations of the androgen receptor gene, while no such mutations were found in latent carcinomas from American men. No mutations were found in clinical carcinomas from either country. These data offer a potential molecular genetic explanation that may partially account for the distinct prostatic carcinoma incidence rates in these two populations.

Amino Acid Sequence↗
PubMed1995

Structural determinants of protein dynamics: analysis of 15N NMR relaxation measurements for main-chain and side-chain nuclei of hen egg white lysozyme.

15N-labeled hen lysozyme has been studied by 2D and 3D NMR in order to characterize its dynamic behavior. The resonances of all main-chain amide nitrogen atoms were assigned, as were resonances of nitrogen atoms in 28 side chains. Relaxation measurements for the main-chain and arginine and tryptophan side-chain 15N nuclei used standard methods, and those for the 15N nuclei of asparagine and glutamine side chains used pulse sequences designed to remove unwanted relaxation pathways in the NH2 groups. The calculated order parameters (S2) show that the majority of main-chain amides undergo only small amplitude librational motions on a fast time scale (S2 > or = 0.8). Increased main-chain motion (0.5 < S2 < 0.8) is observed for a total of 19 residues located at the C-terminus, in loop and turn regions, and in the first strand of the main beta-sheet. Order parameters derived for the side chains range from 0.05 to 0.9; five of the six tryptophan residues have high order parameters (S2 > or = 0.8), consistent with their location in the closely packed core of the protein, whereas the order parameters between 0.05 and 0.3 for arginine residues confirm increased side-chain mobility at the protein surface. Order parameters for the side chains of asparagine and glutamine residues range from 0.2 to 0.8; high values are found for side chains that have low solvent accessible surfaces and well-defined chi 1 values, as measured by 3J alpha beta coupling constants. Many of the main-chain and side-chain groups with low order parameters have higher than average temperature factors in X-ray crystal structures and increased positional uncertainty in NMR solution structures. They also tend to lack persistent hydrogen bond interactions and protection against amide hydrogen exchange. The most significant correlations are found between residues with low order parameters and high surface accessibility in both crystal and solution structures. The results suggest that a lack of van der Waals contacts is a major determinant of side-chain and main-chain mobility in proteins.

Amino Acid Sequence↗