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S Linn

Publications and source records attributed to S Linn.

At least 37 records · Page 2Linked to original sources
PubMed2000

Human damage-specific DNA-binding protein p48. Characterization of XPE mutations and regulation following UV irradiation.

Damage-specific DNA binding (DDB) activity purifies from HeLa cells as a heterodimer (p127 and p48) and is absent from cells of a subset (Ddb(-)) of xeroderma pigmentosum Group E (XPE) patients. Each subunit was overexpressed in insect cells and purified. Both must be present for the damaged DNA band shift characteristic of the HeLa heterodimer. However, overexpressed p48 peptides containing the mutations found in three Ddb(-) XPE strains are inactive, and wild type p48 restores DDB activity to extracts from a fourth XPE Ddb(-) strain, GM01389, in which compound heterozygous mutations in DDB2 (p48) lead to a L350P change from one allele and a Asn-349 deletion from the other. Although these results indicate that these mutations are each responsible for the loss of DDB activity, they do not affect nuclear localization of p48. In normal fibroblasts, a 4-fold increase in p48 mRNA amount was observed 38 h after UV irradiation, preceding a similar elevation in p48 protein and DDB activity at 48 h, implying that p48 limits DDB activity in vivo. Because DNA repair is virtually complete before 48 h, a role for DDB other than DNA repair is suggested.

Amino Acid Substitution↗
PubMed2000

Nuclear transport of human DDB protein induced by ultraviolet light.

Human damage-specific DNA-binding (DDB) protein can be purified as a heterodimer (p48 and p127) that binds to DNA damaged by ultraviolet light. We report here the effects of UV irradiation on the cellular localization of each DDB subunit as a function of time using green fluorescent fusion proteins in three diploid fibroblast strains: repair-proficient IMR-90 and two repair-deficient xeroderma pigmentosum group E strains (XP95TO and XP3RO). Although p48 remained in the nucleus after UV irradiation, a dynamic nuclear accumulation of p127 from the cytoplasm was found after 24 h. In IMR-90 cells, the nuclear localization of p127 corresponded to the up-regulation of p48 mRNA and protein levels and of DDB activity. XP3RO cells showed delayed but similar kinetics with less transport, whereas XP95TO cells appeared to have different kinetics, suggesting that these cells exhibit different defects in p127 translocation. We propose that p48 might act as the transporter for nuclear entry of p127 but that a third factor might be necessary for efficient transportation.

Carbohydrates↗
PubMed2000

Studies of the murine DDB1 and DDB2 genes.

Human DDB (Damaged DNA Binding protein) is a heterodimer of 48 and 127kDa subunits whose activity is absent from cell strains derived from a subset of Xeroderma Pigmentosum (XP) complementation group E individuals (Ddb(-)) [Keeney, S., Wein, H., and Linn, S., (1992). Mut. Res. 273, 49-56]. Whereas in vivo DNA repair appears to be compromised in both Ddb(-) and Ddb(+) XPE cells, DDB activity is not necessary for nucleotide excision repair (NER) in vitro. In this study, the presence of a specific UV-damaged DNA binding activity in mouse cell-free extracts that is comparable to the activity observed in HeLa cells was demonstrated. The mouse DDB2 cDNA, coding for DDB p48 subunit, was cloned and the partial genomic structure of DDB2 was obtained. A search of current databases revealed amino acid sequences of mouse and Drosophila predicted p127 homologues, but not of a Drosophila p48 homologue. The alignment of these higher eukaryotic p127 sequences uncovered the presence of three highly conserved domains in the p127 polypeptides which we hypothesize could function in DNA binding, transcription-transactivation, and protein-protein interaction, respectively.

Amino Acid Sequence↗
PubMed2000

Long-term prognosis of acute pulmonary oedema--an ominous outcome.

BACKGROUND: Acute pulmonary oedema (APOE) is a major health problem, leading to poor hospital and long-term outcomes. There is a relative paucity of studies describing prognosis of consecutive unsolicited patients diagnosed with APOE and hospitalized in internal medicine departments. AIMS: To describe the clinical profile and outcome (in hospital and 1-year prognosis) of successive unselected patients with APOE, in a prospective observational study. METHODS AND RESULTS: The study population included 150 consecutive unsolicited patients (90 men, 60 women; median age 75 years) with APOE all hospitalized in an internal medicine department, in a 900-bed care centre. Ischaemic heart disease (IHD), hypertension and diabetes were present in 85%, 70% and 52% of patients, respectively. The most common precipitating factors for APOE included high blood pressure (29%), rapid atrial fibrillation (29%), unstable angina pectoris (25%), infection (18%) and acute myocardial infarction (MI; 15%). Eighteen patients (12%) died in hospital, with 82% of these deaths attributed to cardiac pump failure. Predictors for an increased in-hospital mortality included: diabetes (P<0.05), orthopnoea (P<0. 05), echocardiographic finding of depressed global left ventricular systolic function (P<0.001), acute MI during hospital stay (P<0.001), hypotension/shock (P<0.05), and the need for mechanical ventilation (P<0.001). After a median hospital stay of 10 days, 132 patients were discharged home. The 1-year mortality was 40%. Only the presence of pleural effusion was found as a predictor for 1-year mortality. CONCLUSION: Most patients with APOE in this study are elderly, and have IHD, hypertension, diabetes and a previous history of APOE. The overall mortality is high (in-hospital, 12%: 1-year, 40%). Left ventricular dysfunction was associated with high in-hospital mortality, but not with long-term prognosis.

Adult↗
PubMed2000

Epidemiological study of classic Kaposi's sarcoma: a retrospective review of 125 cases from Northern Israel.

BACKGROUND: The morphology of Kaposi's sarcoma is clinically and histologically the same in all clinical forms of the disease. However, there is a difference in the clinical and biological behaviour of the different forms of the disease. The behaviour also differs among individuals with the same form. The factors involved in the initiation and prognosis of the disease are still unknown. The classical form is more common in middle-aged Jews of East European or Mediterranean origin, people of Italian and southern Greek origin. Classic Kaposi's Sarcoma is seen relatively more frequently in Israel than in many other countries. OBJECTIVE: The aim of this study was to examine risk factors that influence the development and course of the disease. METHODS: This retrospective study includes 125 patients with Kaposi's sarcoma, all diagnosed and followed in the Department of Dermatology at Rambam Medical Center in Haifa. RESULTS: The group included 85 (68%) men and 40 (32%) women. Fourteen subjects received corticosteroid therapy and three were kidney transplant recipients. Age at onset of the disease was 21-87 years, with a mean age of 67. A total of 121 patients (96.8%) were Jews and four (3.2%) were non-Jews. A majority (61.6%) were of East European origin. The number of new cases each year was constant in relation to the general population, except for two peaks, one in 1970 and another in 1986-89. The lower limbs were involved in most patients. Extracutaneous involvement was present in 18.4%. Of all the subjects, 28 (22.4%) had diabetes mellitus and 21 (16.8%) had a second primary malignancy. The malignancies were of lymphoreticular origin in 10 patients, four in the urinary bladder, three had carcinoma of the large bowel and one of the pancreas. CONCLUSION: Our study shows similar clinical findings to those described in other series. The relatively high frequency of carcinomas of the colon and urinary bladder was not reported elsewhere. We observed a consistent rate of new cases each year with two peaks in 1970 and 1986-1989, the cause of which deserves explanation. Of interest is the relative rise in the number of females with Kaposi's sarcoma. A relative high risk for developing Kaposi's sarcoma has been found among Jews of Ashkenazi origin compared to those of other ethnic groups. Israeli-born subjects presented a relatively more aggressive course of disease than others.

Adult↗
PubMed2000

Xeroderma pigmentosum variant heterozygotes show reduced levels of recovery of replicative DNA synthesis in the presence of caffeine after ultraviolet irradiation.

Patients with xeroderma pigmentosum variant show clinical photosensitivity, skin neoplasias induced by ultraviolet light, and defective postreplication repair, but normal nucleotide excision repair. We recently reported an alternative, simple method for the diagnosis of xeroderma pigmentosum variant that measures by autoradiography three cellular markers for DNA repair after ultraviolet irradiation: unscheduled DNA synthesis, recovery of RNA synthesis, and recovery of replicative DNA synthesis. Among hereditary photosensitive disorders, including other xeroderma pigmentosum groups, Cockayne syndrome, and a newly established ultraviolet-sensitive syndrome, only xeroderma pigmentosum variant cells exhibited normal unscheduled DNA synthesis, normal recovery of RNA synthesis, but reduced recovery of replicative DNA synthesis (51 +/- 6% the rate relative to normal controls). This reduction of recovery of replicative DNA synthesis was enhanced in the presence of a nontoxic level of caffeine to 36 +/- 5%. In this study we assess the cellular markers in two independent families that included two photosensitive patients that were identified as xeroderma pigmentosum variant. Cells from heterozygotic parents showed normal levels of unscheduled DNA synthesis, recovery of RNA synthesis, and recovery of replicative DNA synthesis, but reduced rates of recovery of replicative DNA synthesis in the presence of 1 mM caffeine (53 +/- 8% relative to the normal control). Furthermore, with a colony-forming assay, the cells showed normal survival by ultraviolet without caffeine, but slightly reduced survival by ultraviolet with 1 mM caffeine present. In one family, we confirmed inheritance of two heterozygous mis-sense mutations. One mutation is an A-->G transition at nucleotide 1840 that generates a K535E mis-sense mutation. Another mutation is an A-->C transversion at nucleotide 2003 that generates a K589 mis-sense mutation. Each of these mutations were absent in 52 unrelated Japanese individuals. These results suggest that xeroderma pigmentosum variant heterozygotes can be identified by their sensitivity to ultraviolet irradiation in the presence of nontoxic levels of caffeine.

Adult↗
PubMed2000

Reinvestigation of the classification of five cell strains of xeroderma pigmentosum group E with reclassification of three of them.

Xeroderma pigmentosum is a photosensitive syndrome caused by a defect in nucleotide excision repair or postreplication repair. Individuals of xeroderma pigmentosum group E (xeroderma pigmentosum E) have a mild clinical form of the disease and their cells exhibit a high level of nucleotide excision repair as measured by unscheduled DNA synthesis, as well as biochemical heterogeneity. Cell strains from one group of xeroderma pigmentosum E patients have normal damage-specific DNA binding activity (Ddb+), whereas others do not (Ddb-). Using a refinement of a previously reported cell fusion complementation assay, the previously assigned Ddb+ xeroderma pigmentosum E strains, XP89TO, XP43TO, and XP24KO, with various phenotypes in DNA repair markers, were reassigned to xeroderma pigmentosum group F, xeroderma pigmentosum variant, and ultraviolet-sensitive syndrome, respectively. The Ddb- xeroderma pigmentosum E strains, XP82TO, and GM02415B, which showed almost normal cellular phenotypes in DNA repair markers, however, remained assigned to xeroderma pigmentosum group E. With the exception of the Ddb+ strain XP89TO, which demonstrated defective nucleotide excision repair, both Ddb- and Ddb+ xeroderma pigmentosum E cells exhibited the same levels of variation in unscheduled DNA synthesis that were seen in normal control cells. By genome DNA sequencing, the two Ddb- xeroderma pigmentosum E strains were shown to have mutations in the DDB2 gene, confirming previous reports for XP82TO and GM02415B, and validating the classification of both cells. As only the Ddb- strains investigated remain classified in the xeroderma pigmentosum E complementation group, it is feasible that only Ddb- cells are xeroderma pigmentosum E and that mutations in the DDB2 gene are solely responsible for the xeroderma pigmentosum E group.

DNA↗
PubMed1999

Sequence-specific DNA cleavage by Fe2+-mediated fenton reactions has possible biological implications.

Preferential cleavage sites have been determined for Fe2+/H2O2-mediated oxidations of DNA. In 50 mM H2O2, preferential cleavages occurred at the nucleoside 5' to each of the dG moieties in the sequence RGGG, a sequence found in a majority of telomere repeats. Within a plasmid containing a (TTAGGG)81 human telomere insert, 7-fold more strand breakage occurred in the restriction fragment with the insert than in a similar-sized control fragment. This result implies that telomeric DNA could protect coding DNA from oxidative damage and might also link oxidative damage and iron load to telomere shortening and aging. In micromolar H2O2, preferential cleavage occurred at the thymidine within the sequence RTGR, a sequence frequently found to be required in promoters for normal responses of many procaryotic and eucaryotic genes to iron or oxygen stress. Computer modeling of the interaction of Fe2+ with RTGR in B-DNA suggests that due to steric hindrance with the thymine methyl, Fe2+ associates in a specific manner with the thymine flipped out from the base stack so as to allow an octahedrally-oriented coordination of the Fe2+ with the three purine N7 residues. Fe2+-dependent changes in NMR spectra of duplex oligonucleotides containing ATGA versus those containing AUGA or A5mCGA were consistent with this model.

Base Sequence↗
PubMed1999

Continued expansion of the nitinol self-expanding coronary stent: angiographic analysis and 1-year clinical follow-up.

BACKGROUND: This study sought to report the first-year clinical outcome with the nitinol self-expanding coil stent and to provide angiographic data on the effect of self-expansion during implantation and follow-up. Self-expanding stents do not reach their nominal diameter at implantation. The long-term effects may therefore depend, in part, on continued expansion after initial implantation. METHODS: Between January 1995 and January 1996, 86 stents were deployed in 64 patients for indication of suboptimal results. All patients were clinically followed up for 1 year, and 72% had follow-up angiography. RESULTS: The majority (55%) of the lesions were class B2 or C. Balloon angioplasty increased the minimal lumen diameter from 1.07 +/- 0.73 mm to 2.24 +/- 0.57 mm; stent deployment further increased the diameter to 2.63 +/- 0.48 mm, and within-stent balloon dilatation to 2.96 +/- 0.62 mm. Angiographic follow-up performed at 7.8 +/- 1.1 months (range 7-9 months) showed that the minimal lumen diameter was 2.15 +/- 0.80 mm (late lumen loss of 0.81 +/- 0.69 mm), and the mean stent diameter expanded to 3.58 +/- 0.48 mm (self-expanding late stent gain of 0.62 +/- 0.55 mm). The extent of this expansion was inversely related to the late lumen loss (r = 0.67, slope 0.81, P <.01). At 1 year 51 (80%) of 64 patients were event free; 3 had undergone coronary artery bypass grafting, 2 had had a myocardial infarction, and 9 had repeat angioplasty. In the subgroup of a simple lesion (<15 mm) covered by 1 stent, 18 (86%) of 21 patients were event free. CONCLUSIONS: The self-expanding nitinol stent exerts its acute effect on minimal lumen diameter through its intrinsic radial force aided by balloon expansion. The stent continues to expand until it reaches its nominal diameter over the follow-up period. The extent of this expansion is inversely related to the late lumen loss, leading to an acceptable rate of long-term clinical events in this first cohort of patients with complex disease morphology.

Alloys↗
PubMed1999

The D allele of the angiotensin-converting enzyme gene contributes towards blood LDL-cholesterol levels and the presence of hypertension.

Coronary artery disease is a polygenic disease whose phenotypic manifestation depends on the interaction of the genetic background with a number of environmental factors. Recently, the gene coding for the angiotensin-converting enzyme (ACE) has been characterized and a deletion/insertion (D/I) polymorphism was defined. The prevalence of the three genotypes and their association with coronary artery disease (CAD) differ in different population groups. Mostly, the D allele was found as a significant risk factor for CAD, independently from other risk factors. In the present study, we determined the distribution of ACE alleles (D or I) in a cohort of healthy Israeli men and examined the correlation of the different genotypes with various CAD risk factors. We found LDL cholesterol levels to be highest in the DD genotype group, intermediate in the DI genotype group and lowest in the II genotype group. We also found higher blood pressure levels in subjects bearing the D allele compared to II homozygous subjects. In conclusion, it appears that the genetic influence of the D/I polymorphism on CAD manifests primarily through traditional risk factors.

Adult↗
PubMed1999

One-year clinical follow-up with the serpentine balloon expandable stent: report of the first 100 patients.

BACKGROUND: We recently reported a high technical and 30-day clinical success rate among the first 100 patients treated with the tubular, serpentine design, stainless steel, balloon-expandable stent (beStent) in Israel. The present study examined the clinical results in these patients after the first year. METHODS: Seventy-eight men and 22 women were included in the study. Previous myocardial infarction, bypass surgery and percutaneous transluminal coronary angioplasty had occurred in 52%, 12% and 26% of the patients, respectively. Diabetes mellitus was present in 30 patients and hypertension in 34 patients. One hundred and forty-eight stents of 15, 25, and 35 mm lengths were used. The indications for stenting were suboptimal results (n = 85), bailout conditions (n = 10) or for the prevention of restenosis (n = 8), and lesion types were A (n = 10), B1 (n = 29), B2 (n = 20), and C (n = 44). All patients were clinically monitored with regular visits at 1, 3, 6, 9 and 12 months. RESULTS: Overall, the 12-month event-free survival rate was 82%. Subacute thrombosis occurred in two patients. There were two non-cardiac deaths, one O-wave myocardial infarction, six elective bypass surgeries and 12 target lesion revascularizations. Event-free survival was significantly higher for those with lesions shorter than 15 mm than for those with lesions longer than 15 mm (90% versus 67%, P = 0.003), and for women compared with men (96% versus 78%, P = 0.02). CONCLUSIONS: The initial experience with the beStent shows favorable long-term results with an overall event rate of 18% for this subset of relatively complex lesions; higher event rates were observed for longer lesions.

Angioplasty, Balloon, Coronary↗
PubMed1999

The naturally occurring mutants of DDB are impaired in stimulating nuclear import of the p125 subunit and E2F1-activated transcription.

The human UV-damaged-DNA binding protein DDB has been linked to the repair deficiency disease xeroderma pigmentosum group E (XP-E), because a subset of XP-E patients lack the damaged-DNA binding function of DDB. Moreover, the microinjection of purified DDB complements the repair deficiency in XP-E cells lacking DDB. Two naturally occurring XP-E mutations of DDB, 82TO and 2RO, have been characterized. They have single amino acid substitutions (K244E and R273H) within the WD motif of the p48 subunit of DDB, and the mutated proteins lack the damaged-DNA binding activity. In this report, we describe a new function of the p48 subunit of DDB, which reveals additional defects in the function of the XP-E mutants. We show that when the subunits of DDB were expressed individually, p48 localized in the nucleus and p125 localized in the cytoplasm. The coexpression of p125 with p48 resulted in an increased accumulation of p125 in the nucleus, indicating that p48 plays a critical role in the nuclear localization of p125. The mutant forms of p48, 2RO and 82TO, are deficient in stimulating the nuclear accumulation of the p125 subunit of DDB. In addition, the mutant 2RO fails to form a stable complex with the p125 subunit of DDB. Our previous studies indicated that DDB can associate with the transcription factor E2F1 and can function as a transcriptional partner of E2F1. Here we show that the two mutants, while they associate with E2F1 as efficiently as wild-type p48, are severely impaired in stimulating E2F1-activated transcription. This is consistent with our observation that both subunits of DDB are required to stimulate E2F1-activated transcription. The results provide insights into the functions of the subunits of DDB and suggest a possible link between the role of DDB in E2F1-activated transcription and the repair deficiency disease XP-E.

Animals↗
PubMed1998

Diabetic dermopathy and internal complications in diabetes mellitus.

BACKGROUND: Diabetic dermopathy is the most common cutaneous marker of diabetes mellitus. The relationship of diabetic dermopathy to internal complications of diabetes mellitus, such as nephropathy, retinopathy, and neuropathy, is still unknown. METHODS: The possible role of diabetic dermopathy as a clinical sign of internal complications in diabetes mellitus was investigated. One hundred and seventy-three patients with diabetes mellitus, of whom 125 (72%) had insulin-dependent diabetes mellitus and 48 (28%) had non-insulin-dependent diabetes mellitus, were studied. RESULTS: Diabetic dermopathy was present in 69 (40%) of patients, statistically more significant in patients 50 years of age and older. The mean diabetic duration was significantly higher in patients with diabetic dermopathy than in those without. The associations of diabetic dermopathy with retinopathy, nephropathy, and neuropathy were each statistically significant, and the increased frequency of diabetic dermopathy correlated with an increased number of these three complications in each patient. CONCLUSIONS: Some of the factors that affect the development of internal complications in diabetes mellitus may play a role in the development of diabetic dermopathy, and diabetic dermopathy may serve as a clinical sign of an increased likelihood of these internal complications in diabetic patients.

Adolescent↗
PubMed1998

Epidemiology of bicycle injury, head injury, and helmet use among children in British Columbia: a five year descriptive study. Canadian Hospitals Injury, Reporting and Prevention Program (CHIRPP).

OBJECTIVES AND METHODS: Data on 1462 injured bicyclists aged 1-19, obtained over a period of five years from the British Columbia Children's Hospital as part of a national emergency room based program in Canada, were analyzed to describe the epidemiology of injuries, helmet use, and the occurrence of head injuries before the enactment of a new mandatory helmet law. The odds ratio (OR) and 95% confidence interval (CI) were calculated for non-users compared with helmet users. RESULTS: Bicycle injuries comprised 4% of all injuries seen in the five year study period. The proportion of admissions was 12.7% among bicyclists, significantly higher than the 7.9% admissions of all 35,323 non-bicyclist children who were seen during the study period (OR = 1.96, CI = 1.44 to 1.99). Boys were injured more often than girls. The proportion of admissions for boys was 13.8% compared with 10.2% among girls (OR = 1.41, CI = 0.97 to 2.05). More than 70% of injured bicyclists reported no helmet use. The proportion of admissions of injured bicyclists who did not use helmets was always higher than the proportion of admissions of those who used helmets (OR = 2.23, CI = 1.39 to 3.62). Head and face injuries occurred more often among those who did not use helmets (OR = 1.55, CI = 1.18 to 2.04). However, there was no excess of minor head injuries among non-users (OR = 1.10, CI = 0.60 to 2.06). Of the 62 concussions, 57 occurred to non-helmet users (OR = 4.04, CI = 1.55 to 11.47). Most injuries occurred in the upper (46.4%) or lower extremities (32.4%). Dental injuries occurred slightly more often among helmet users compared with non-users but this excess was not statistically significant (OR = 1.29, CI = 0.76 to 2.20). CONCLUSION: The data indicate the need to control injuries by using helmets. A decrease in the number of head injuries and their severity is expected when bicycle helmet use becomes law in British Columbia.

Adolescent↗
PubMed1998

Lack of effect of prophylactic gentamicin treatment on intraocular and extraocular fluid cultures after pars plana vitrectomy.

BACKGROUND AND OBJECTIVE: To analyze the effect of preoperative prophylatic 0.3% gentamicin sulfate eyedrops on intraocular and extraocular fluid cultures after pars plana vitrectomy. PATIENTS AND METHODS: Forty consecutive patients undergoing pars plana vitrectomy were randomly assigned to receive either 0.3% gentamicin eyedrops or placebo preoperatively. Fluids from the vitreous cavity and from the conjunctival sac were collected for bacteriologic studies. RESULTS: Positive cultures from extraocular fluids were obtained in 30.4% of the gentamicin group and 35.3% of the placebo group (P = .75). Furthermore, 1 (3%) of 40 cultures of intraocular fluid and 13 (33%) of 40 cultures of extraocular fluid were positive. Culture growth positivity was not influenced by the patients' age, by diabetes, or by the duration of the operation. CONCLUSIONS: Prophylactic gentamicin treatment by the method applied in this study is not effective on reducing growth positivity. Contaminated extraocular fluid may play an important role in the pathogenesis of bacterial endophthalmitis following pars plana vitrectomy.

Administration, Topical↗
PubMed1997

Purification, cDNA cloning, and gene mapping of the small subunit of human DNA polymerase epsilon.

HeLa DNA polymerase epsilon (pol epsilon), possibly involved in both DNA replication and DNA repair, consists of a catalytic subunit of 261 kDa and a tightly bound peptide with a relative molecular mass of 55 kDa. The cDNA of the 261-kDa polypeptide has been independently cloned, sequenced, and then overexpressed in insect cells to give a soluble, but catalytically unstable protein, suggesting that the small subunit of HeLa pol epsilon might be important for stability. HeLa pol epsilon has been isolated by immunoaffinity purification to obtain sequence information which enabled the cloning of a full-length human cDNA encoding the small subunit. The clone encoded nine proteolytic peptides obtained from the subunit. The 59,434-Da predicated polypeptide has 26% identity and 44% homology to the yeast pol epsilon 80-kDa subunit, DPB2. Using fluorescence in situ hybridization, the human pol epsilon p59 locus (DPE2) was assigned to chromosome 14q13-q21.

Amino Acid Sequence↗