Biomedical subjects
Publications and source records attributed to S Linn.
Trends in the incidence of classic Kaposi's sarcoma in the Jewish population in Israel for the period between 1960 and 1998 were analysed. World standardised incidence rates of 20.7 and 7.5 per million among men and women, respectively, were calculated. The highest incidence rates were displayed by men originated from Africa and by Asian-born women.
BACKGROUND: The morphologic features of swollen disc in the acute stage of optic neuritis and anterior ischaemic optic neuropathy (AION) have been extensively investigated in contrast to the morphologic features of optic disc atrophy after these events. OBJECTIVE: : A prospective study to evaluate the morphologic features of optic disc atrophy 6 months or more after optic neuritis and nonarteritic AION. PATIENTS AND METHODS: A total of 35 optic discs after nonarteritic AION (n=27) and 24 after optic neuritis (n=19) in otherwise healthy subjects have been evaluated by direct fundoscopic examination with a +90 diopters lens and optic disc photography. The average age of patients at the onset of AION was 57.8 years (range: 38-80) and at the onset of optic neuritis was 32.6 (range: 19-46). The female:male ratio was 18 : 17 in the former and 15 : 9 in the latter. The evaluated parameters included: degree of rim pallor (0 to +3), location of rim pallor, height of rim above the retina, depth and width of cup, peripapillary retinal artery to vein (A : V) ratio, and peripapillary pigment epithelial atrophy. A comparison was made also with 17 age-matched normal discs of 17 patients. Statistical significance was calculated with chi(2) and Fisher's exact test. RESULTS: Most of the discs after AION were paler (+2: 70%, +3: 26%) than after optic neuritis (normal colour: 8%, +1: 58%, P< or =0.007). Rim segmental involvement after AION was usually either superior 'altitudinal' (53%) or inferior 'altitudinal' (29%), whereas after optic neuritis, it was usually either temporal-central (papillomacular) (42%) or diffuse temporal (42%, P<0.0001). Discs had lower A : V ratio (1 : 3, 40%) after AION compared with optic neuritis (1 : 3, 8%) (P=0.007). There were no significant differences between the two groups in height of the rim, cupping, and peripapillary atrophy. CONCLUSIONS: : A combination of the degree of rim pallor, location of rim pallor, and A : V ratio may be of value in assessing the aetiology of optic disc atrophy when no previous clinical data are available and a compressive lesion has been ruled out.
An alternative procedure for detection breast cancer was examined based on the observation that lymphocytes re-exposed in vitro to antigenic stimulation will change their intracellular structuredness as measured by polarization of fluorescent light emitted by fluorescein labeled cells (SCM test). The specific antigen MUC-l/SEC was used to elicit such response in lymphocytes of patients with and without breast cancer. Eighty-five samples with breast cancer were tested, of which 72 were correctly diagnosed. Of the 41 controls, 35 were correctly identified as healthy subjects. The sensitivity of the test was 85% and the specificity was 81%. These results suggest a possible valuable method for screening and early detection of breast cancer. The clinical importance of this procedure lies in the ability to screen high-risk populations with higher specificity and sensitivity than any combinations of currently available procedures for breast cancer detection.
Early detection is crucial for successful treatment of all types of cancer. The specificity and sensitivity of the current methods vary from 50% to 80%. The use of specific tumor antigens and cytometric technology has resulted in the development of a new procedure for the early detection of breast tumors. This new method is reported. The test utilizes static cytometry, which records polarization and intensity changes in fluorescent light emitted from each individual lymphocyte obtained from tumor-bearing patients stimulated by the relevant specific tumor antigen. Using MUC-1/SEC as the specific antigen, we detected breast tumors with 85% specificity and 81% sensitivity in 137 breast tumor-bearing women. A significant linear correlation was found between the SCM test and the conventional classification of relative risk for breast cancer in benign lesions, suggesting that this is a precise method that could be used in mass screening for early detection of breast cancer.
A damage-specific DNA binding protein (DDB) activity is absent from a subset (DDB(-)) of cells from individuals initially classified as group E of xeroderma pigmentosum (XP), a hereditary, photosensitive disease with a high incidence of skin malignancies. In these cases, mutations have been identified in the DDB2 gene (DDB2(-)) that codes for the small subunit, p48, of the DDB heterodimer. In four DDB2(- )strains, neither p48 nor DDB activity were observed before or after UV-irradiation, despite an unusually strong up-regulation of DDB2 mRNA levels after UV-irradiation. In a fifth strain, XP82TO, p48 was detectable and both DDB2 mRNA and p48 levels were more up-regulated after UV-irradiation than in normal primary cells. Moreover, DDB activity also became apparent after irradiation. XP82TO showed very mild clinical manifestations compared with the other DDB(-) patients. These results, coupled with our findings that most, if not all DDB(+) cells classified as XP-E were misclassified, suggests a direct correlation between DDB2 levels and the XP-E phenotype.
Nicking of duplex DNA by the iron-mediated Fenton reaction occurs preferentially at a limited number of sequences. Of these, purine-T-G-purine (RTGR) is of particular interest because it is a required element in the upstream regulatory regions of many genes involved in iron and oxidative-stress responses. In order to study the basis of this preferential nicking, NMR studies were undertaken on the RTGR-containing duplex oligonucleotide, d(CGCGATATGACACTAG)/d(CTAGTGTCATATCGCG). One-dimensional and two-dimensional 1H NMR measurements show that Fe(2+) interacts preferentially and reversibly at the ATGA site within the duplex at a rate that is rapid relative to the chemical-shift timescale, while selective paramagnetic NMR line-broadening of the ATGA guanine H8 suggests that Fe(2+) interacts with the guanine N7 moiety. Localization at this site is supported by Fe(2+) titrations of a duplex containing a 7-deazaguanine substitution in place of the guanine in the ATGA sequence. The addition of a 100-fold excess of Mg(2+) over Fe(2+) does not affect the Fe(2+)-dependent broadening. When the ATGA site in the duplex is replaced by ATGT, an RTGR site (GTGA) is created on the opposite strand. Preferential iron localization then takes place at the 3' guanine in GTGA but no longer at the guanine in ATGT, consistent with the lack of preferential cleavage of ATGT sites relative to ATGA sites.
We propose a new role of retinoblastoma protein as a cell growth activator in its phosphorylated form. The hyper-phosphorylated retinoblastoma protein generated by the action of cdk2/cyclin E strongly stimulated the activity of DNA polymerase alpha, but did not stimulate DNA polymerases delta, epsilon, or primase. But, cdk4/cyclin D-phosphorylated retinoblastoma protein showed little stimulation. Hyper-phosphorylated retinoblastoma protein interacted with the catalytic subunit of DNA polymerase alpha, and stabilised DNA polymerase alpha from heat inactivation at 45 degrees C. These results suggest that in G1 phase, hypo-phosphorylated retinoblastoma protein suppresses the progression of cell cycle as a transcription inhibitor, but that after phosphorylation by cdk2/cyclin E at the G1/S boundary, hyper-phosphorylated retinoblastoma protein acts as a cell-cycle promoter by optimising the DNA polymerase alpha reaction.
Human cells contain a protein that binds to UV-irradiated DNA with high affinity. This protein, damaged DNA-binding protein (DDB), is a heterodimer of two polypeptides, p127 and p48. Recent in vivo studies suggested that DDB is involved in global genome repair of cyclobutane pyrimidine dimers (CPDs), but the mechanism remains unclear. Here, we show that in vitro DDB directly stimulates the excision of CPDs but not (6-4)photoproducts. The excision activity of cell-free extracts from Chinese hamster AA8 cell line that lacks DDB activity was increased 3-4-fold by recombinant DDB heterodimer but not p127 subunit alone. Moreover, the addition of XPA or XPA + replication protein A (RPA), which themselves enhanced excision, also enhanced the excision in the presence of DDB. DDB was found to elevate the binding of XPA to damaged DNA and to make a complex with damaged DNA and XPA or XPA + RPA as judged by both electrophoretic mobility shift assays and DNase I protection assays. These results suggest that DDB assists in the recognition of CPDs by core NER factors, possibly through the efficient recruitment of XPA or XPA.RPA, and thus stimulates the excision reaction of CPDs.
OBJECTIVE: To determine melatonin production in hyperandrogenic women. DESIGN: Controlled prospective study. SETTING: Outpatients in an academic medical center. PATIENT(S): Twenty-two women with polycystic ovary syndrome (PCOS), 20 women with idiopathic hirsutism, and 15 age-matched individuals who had similar body mass indexes as controls. INTERVENTION(S): Fasting blood samples and 24-hour urinary samples were obtained from all participants. MAIN OUTCOME MEASURE(S): All participants provided serum samples for the measurement of LH, FSH, testosterone, E(2), DHEAS, 17 alpha-hydroxyprogesterone (17-OHP), and insulin levels, as well as urinary 6-sulfatoxymelatonin (aMT6s). RESULT(S): Women with PCOS had higher aMT6s, testosterone, LH/FSH ratio, and insulin values than either women with idiopathic hirsutism or control women. Testosterone inversely correlated with aMT6s in PCOS. Regression analysis revealed that only testosterone was an important determinant of aMT6s in PCOS. CONCLUSION(S): Women with PCOS have increased melatonin production.
SUMMARY: Current model systems used to investigate angiogenesis in vivo rely on the interpretation of results obtained with nonhuman endothelial cells. Recent advances in tissue engineering and molecular biology suggest the possibility of engineering human microvessels in vivo. Here we show that human dermal microvascular endothelial cells (HDMEC) transplanted into severe combined immunodeficient (SCID) mice on biodegradable polymer matrices differentiate into functional human microvessels that anastomose with the mouse vasculature. HDMEC were stably transduced with Flag epitope or alkaline phosphatase to confirm the human origin of the microvessels. Endothelial cells appeared dispersed throughout the sponge 1 day after transplantation, became organized into empty tubular structures by Day 5, and differentiated into functional microvessels within 7 to 10 days. Human microvessels in SCID mice expressed the physiological markers of angiogenesis: CD31, CD34, vascular cellular adhesion molecule 1 (VCAM-1), and intercellular adhesion molecule 1 (ICAM-1). Human endothelial cells became invested by perivascular smooth muscle alpha-actin-expressing mouse cells 21 days after implantation. This model was used previously to demonstrate that overexpression of the antiapoptotic protein Bcl-2 in HDMEC enhances neovascularization, and that apoptotic disruption of tumor microvessels is associated with apoptosis of surrounding tumor cells. The proposed SCID mouse model of human angiogenesis is ideally suited for the study of the physiology of microvessel development, pathologic neovascular responses such as tumor angiogenesis, and for the development and investigation of strategies designed to enhance the neovascularization of engineered human tissues and organs.
Explore the source record for details and available documents.
This article reports on the sensitivity and positive predictive value of clinical diagnosis of benign and malignant skin tumors by expert plastic surgeons in an Israeli clinic. Most published reports have focused on the sensitivity of clinicians' diagnoses, a general measure of the physician's skill that does not predict the rate of accuracy of a physician's diagnoses. Our study of 835 lesions in 778 patients, one of the largest Israeli series, assesses the clinical diagnosis of malignant and benign skin tumors and is one of the few that provide information on the positive predictive value, the measure that is of interest to both physicians and patients. The majority of tumors were benign (56.8 percent), 31.6 percent were malignant, and 11.6 percent were premalignant. Among the 474 benign lesions, 46 percent were nevi. The most common nevi subclass was compound nevi (53 percent), 9 percent of the nevi were dysplastic, and 5 percent were blue nevi. The most common malignant tumor was basal cell carcinoma, accounting for 78 percent of malignant tumors. Although sensitivity for clinical diagnosis of malignancy was 91.3 percent, the positive predictive value for clinical diagnosis of malignancy was 71.3 percent. The sensitivity rate for clinically diagnosing premalignant tumors was 42.3 percent, whereas the positive predictive value for these diagnoses was higher (64.1 percent). The sensitivity rate for diagnosis of all benign lesions was 85.9 percent, and the positive predictive value was 94.2 percent. The sensitivity rate for diagnosis of all nevi was 87.6 percent, and the positive predictive value was 85.7 percent: i.e., only seven of the 218 pathologically proven diagnoses of nevi (3.2 percent) were falsely diagnosed as malignant lesions. Even more interestingly, five of the 223 clinical diagnoses of nevi (2.2 percent) were pathologically proven to be malignant melanomas, and seven were found to be premalignant lesions (3.1 percent). It was concluded that publications which report only on the sensitivity neglect to provide information of interest regarding the positive predictive value. Often, positive predictive value is qualitatively different from the sensitivity, and thus relying only on the sensitivity may lead to incorrect evaluation of a clinical judgment, which may result in erroneous surgical decisions.
OBJECTIVE: (1) Examine variations in AHC indicators across age groups and payor types; (2) evaluate the impact of individual and community characteristics on AHC indicators; and (3) investigate the effect of adjustment for age and other factors on AHC indicators. MCOs can use AHC hospitalization and inpatient days to develop focused strategies in reducing AHC hospitalization. But biased comparisons often occur without adjustment for confounding factors. This study demonstrates that age and age/gender adjustments are needed for privately insured and Medicare patients while additional adjustment for community characteristics is needed for Medicaid and Self-Pay patients.
Human DNA polymerase epsilon (pol epsilon) normally contains a 261-kDa catalytic subunit (p261), but from some sources it is isolated as a 140-kDa catalytic core of p261. This shortened form possesses normal or somewhat enhanced polymerase activity and its significance is unknown. We report here that caspase-3 and calpain can form p140 from p261 in vitro and in vivo and that during early stages of apoptosis induced in Jurkat cells by staurosporine or anti-Fas-activating antibody, p261 is cleaved into p140 by caspase-3. At later stages, activated calpain might also contribute to this conversion. The sites of cleavage by caspase-3 have been identified, and mutations at these 'DEAD boxes' resulted in cleavage-resistant enzyme. Cleavage at these sites separates the 'N-terminal catalytic core' from the 'C-terminal' regions described for p261. Cleavage does not occur during necrosis or following exposure to H(2)O(2) or methanesulfonic acid methyl ester. p140 is unlikely to be able to functionally replace p261 in vivo, since it does not bind to PCNA or the other pol epsilon subunits.
Dehydroaltenusin was found to be an inhibitor of mammalian DNA polymerase alpha (pol alpha) in vitro. Surprisingly, among the polymerases and DNA metabolic enzymes tested, dehydroaltenusin inhibited only mammalian pol alpha. Dehydroaltenusin did not influence the activities of the other replicative DNA polymerases, such as delta and epsilon; it also showed no effect even on the pol alpha activity from another vertebrate (fish) or plant species. The inhibitory effect of dehydroaltenusin on mammalian pol alpha was dose-dependent, and 50% inhibition was observed at a concentration of 0.5 microm. Dehydroaltenusin-induced inhibition of mammalian pol alpha activity was competitive with the template-primer and non-competitive with the dNTP substrate. BIAcore analysis demonstrated that dehydroaltenusin bound to the core domain of the largest subunit, p180, of mouse pol alpha, which has catalytic activity, but did not bind to the smallest subunit or the DNA primase p46 of mouse pol alpha. These results suggest that the dehydroaltenusin molecule competes with the template-primer molecule on its binding site of the catalytic domain of mammalian pol alpha, binds to the site, and simultaneously disturbs dNTP substrate incorporation into the template-primer.
Explore the source record for details and available documents.
MDM2 is induced by p53 in response to cellular insults such as DNA damage and can have effects upon the cell cycle that are independent or downstream of p53. We used a yeast two-hybrid screen to identify proteins that bind to MDM2 and which therefore might be involved in these effects. We found that MDM2 can bind to the C-terminus of the catalytic subunit of DNA polymerase epsilon (DNA pol epsilon), to a region that is known to be essential in yeast. In an in vitro system we confirmed that MDM2 could bind to the homologous regions of both mouse and human DNA pol epsilon and to full-length human DNA pol epsilon. DNA pol epsilon co-immunoprecipitated with MDM2 from transfected H1299 cells and also from a HeLa cell nuclear extract. We show here that the DNA pol epsilon-interacting domain of MDM2 is located between amino acids 50 and 166. Our studies provide evidence that MDM2 interacts with a region of DNA pol epsilon that plays a critical role in the function of DNA pol epsilon.
HeLa DNA polymerase epsilon (pol epsilon), possibly involved in both DNA replication and DNA repair, was previously isolated as a complex of a 261-kDa catalytic subunit and a tightly bound 59-kDa accessory protein. Saccharomyces cerevisiae pol epsilon, however, consists of four subunits: a 256-kDa catalytic subunit with 39% identity to HeLa pol epsilon p261, a 80-kDa subunit (DPB2) with 26% identity to HeLa pol epsilon p59, a 23-kDa subunit (DPB3), and a 22-kDa subunit (DPB4). We report here the identification and the cloning of two additional subunits of HeLa pol epsilon, p17, and p12. Both proteins contain histone fold motifs which are present also in S. cerevisiae DPB4 and DPB3. The histone fold motifs of p17 and DPB4 are related to that of subunit A of the CCAAT binding factor, whereas the histone fold motifs found in p12 and DPB3 are homologous to that in subunit C of CCAAT binding factor. p17 together with p12, but not p17 or p12 alone, interact with both p261 and p59 subunits of HeLa pol epsilon. The genes for p17 and p12 can be assigned to chromosome locations 9q33 and 2p12, respectively.