Search PubMed⌕ Search

Biomedical subjects

N Simon

Publications and source records attributed to N Simon.

At least 73 records · Page 4Linked to original sources
PubMed1994

A twelve year natural history of hepatitis C virus infection in hemodialyzed patients.

A prospective non-A, non-B follow-up program, implemented in a hepatitis B surface antigen-free dialysis unit, enabled us to report on the natural history of hepatitis C virus (HCV) infection in hemodialyzed patients between 1980 and 1992. For this program, every patient was prospectively monitored every two weeks for alanine amino transferase (ALT) activity, and every month for gammaglutamyl transpeptidase (GGT) activity and systematic collection of frozen sera. Sequences of stored sera from 217 patients were repeatedly tested for anti-HCV antibodies using second generation assays. Eighty-six of the 217 patients (39.6%), including 61 of the 67 patients with non-A, non-B hepatitis (91%), had HCV infection repeatedly evidenced by positive ELISA in all, and confirmed by RIBA in 84 of 86 (97.5%). In addition, 19 out of 23 patients (82.6%) were positive for HCV RNA by the polymerase chain reaction (PCR). Of the 86 anti-HCV positive patients, 41 had previously acquired HCV infection, and 45 seroconverted during chronic dialysis. Of these, all but one patient developed hepatitis with raised ALT activity which lasted for at least six months in all. Only 29 of 45 patients (64.5%) had a history of blood transfusion. Seventy-eight of the 86 patients (91%) who were followed up for one to 11.5 years (median 5) retained anti-HCV for several years. Nineteen liver biopsies performed in 16 patients showed chronic active hepatitis in 8 (50%) and hepatocellular carcinoma without cirrhosis in one patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine Transaminase↗
PubMed1994

Anti-hepatitis C virus (anti-HCV) seroconversion in patients undergoing hemodialysis: comparison of second- and third-generation anti-HCV assays.

BACKGROUND: The results obtained in sequential specimens from recently infected subjects generally provide the best means of comparing the sensitivity of assays. STUDY DESIGN AND METHODS: The sensitivity of second- and third-generation assays for antibody to hepatitis C virus (HCV) was compared on sequential specimens, generally collected at monthly intervals from 45 patients undergoing hemodialysis who seroconverted for HCV between 1980 and 1990. RESULTS: Fifteen patients (33%) were positive earlier in the third-generation enzyme-linked immunosorbent assay (ELISA), with a mean difference of 17 days (range, 7-30) between the last negative and the first positive specimens. At the first rise in alanine aminotransferase, and at its peak, 63 and 91 percent of the patients, respectively, were anti-HCV positive in the third-generation ELISA. Third-generation recombinant immunoblot assay (RIBA) reacted at the same time as third-generation ELISA. Of the first specimens that were positive in second-generation ELISA, 44 percent reacted and 56 percent were indeterminate in third-generation RIBA, while 10 percent reacted, 72 percent were indeterminate, and 18 percent did not react in second-generation RIBA. From the beginning to the end of the follow-up, antibody to c33c was the most prevalent, followed in descending order by antibody to c22-3, antibody to c100-3, and antibody to NS5: 56, 54, 26, and 18 percent, respectively, at time 0, and 100, 86, 83, and 31 percent, respectively, 12 months later. CONCLUSION: Third-generation assays (both ELISA and RIBA) were more sensitive than second-generation assays in the diagnosis of HCV infection, in that positive results were obtained earlier and a higher proportion of specimens were confirmed positive in RIBA testing.

Alanine Transaminase↗
PubMed1994

Landscape patterns of abundance of Ixodes scapularis (Acari: Ixodidae) on Shelter Island, New York.

Nymphal Ixodes scapularis Say, the vector of Lyme borreliosis, was most common in forested areas across Shelter Island, Suffolk County, New York, and least common in xeric habitats such as beach and grassland. At the scale of individual house yards, nymphs were most common at wooded edges of property and least common on lawns. The abundance of ticks at yard edges was positively correlated with numbers on lawns and in landscaping, suggesting that tick abundance in woods affects abundances in adjacent yards. Because 57% of all yard area is adjacent to woodlands on Shelter Island, public health efforts to reduce tick populations in wooded areas should supplement efforts by individual yard owners to decrease risk. Methods of tick control for woodlands should also be evaluated for their effect on tick populations in adjacent yard habitats.

Animals↗
PubMed1994

[Secondary hemomediastinum after positioning a hemodialysis catheter].

We describe a case of late perforation of the superior vena cava by a hemodialysis catheter inserted via the left internal jugular vein. This resulted in extravasation of blood. Malposition of the catheter was confirmed by CT scan. Removal of the catheter resulted in rapid resolution of symptoms. Confirmation of correct placement of central venous catheter must be obtained by chest X-ray contrast study.

Adult↗
PubMed1992

Basement membrane components (matrigel) promote the tumorigenicity of human breast adenocarcinoma MCF7 cells and provide an in vivo model to assess the responsiveness of cells to estrogen.

The ability to transplant human tumors into athymic nude mice allows studies of tumor cells in vivo. However, after s.c. injection the incidence of tumor and metastases in nude mice is frequently low. We have studied the tumorigenicity in nude mice of estradiol (E2)-sensitive breast adenocarcinoma MCF7 cells. Matrigel, an extract of basement membrane proteins, induces rapid tumor development after s.c. injection of MCF7 cells. In the absence of this matrice, MCF7 cells failed to induce tumor growth. In this in vivo model, MCF7 cells were analysed for their E2 sensitivity. Two weeks after inoculation in the presence of matrigel, cells formed growing tumors in intact mice supplemented with E2. In ovariectomized or untreated mice, tumor appearance was delayed and the growth level was very low. Thus, MCF7 cells formed tumors in the absence of E2 but retained in vivo their responsiveness to estrogen. Growing human tumors in nude mice provides a rapid and useful model for testing the sensitivity of cells to hormone.

Adenocarcinoma↗
PubMed1992

Erythrocyte uroporphyrinogen decarboxylase activity in 80 unrelated patients with porphyria cutanea tarda.

To estimate the prevalence of the subgroups of porphyria cutanea tarda (PCT), erythrocyte uroporphyrinogen decarboxylase (UD) activity was measured in 80 unrelated patients with PCT, and in 45 of their relatives by using pentacarboxyl-porphyrinogen III as substrate. The subgroups were differentiated by analysis of the urinary porphyrins of the patients and 119 of their relatives. Of the patients, 77.5% were found to be suffering from the sporadic form of PCT (type I PCT), and 22.5% from the familial form (type II PCT). Every patient with PCT had previously been affected by alcohol, oestrogen or some other liver-damaging factor. The relative frequency of familial PCT was higher in females (nine of 15) than in males (nine of 65), which suggests that inheritance of the gene for type II PCT may predispose to oestrogen-precipitated PCT. The onset of type II PCT occurred at a lower age than that of type I (42.6 vs. 47.0 years). The findings suggest an increased risk of precipitating factors in carriers of an inherited UD deficiency.

Adult↗
PubMed1992

Evaluation of in vitro reconstituted basement membrane assay to assess the invasiveness of tumor cells.

The crossing of tumor cells through basement membranes represents a critical step in the metastatic process. We have used a reconstituted basement membrane (matrigel) coated on filter in a Boyden chamber to assess the invasive potential of tumor and normal cells. No correlation was found between chemoinvasion in vitro and the metastatic potential in vivo. Normal human fibroblasts and murine 3T3 fibroblasts penetrated filters coated with matrigel. On the other hand, the tumoral cells (MCF7, MCF7 gpt, MCF7 ras, BeWo, JAR, NUC-1 cells) were unable to cross the matrix. Our results suggest that in our conditions, this widely used model to assess tumoral invasion does not provide a universal assay to test the invasiveness of tumor cells. Penetration of the matrigel appears to be related to chemotactic or haptotactic responses depending upon cell types. Our data emphasize the variability of molecular events associated with basement membrane invasion.

3T3 Cells↗
PubMed1992

Fetal weight-cerebellar diameter discordance as an indicator of asymmetrical fetal growth impairment.

In this study on the effect of fetal growth impairment < or = 25th percentile on the transverse cerebellar diameter and its relationship with other fetal biometric parameters, the sample comprised 50 women with singleton pregnancies referred for ultrasound evaluation because of clinically suspected intrauterine growth retardation. The cerebellar diameter of asymmetrically growth-impaired fetuses remained within the normal range although it was found to be reduced when compared with that of normal fetuses (4.4 +/- 0.9 versus 4.8 +/- 0.7, P < .05). Although other biometric parameters (biparietal diameter, femur length and abdominal and head circumferences) were also reduced in growth-impaired fetuses, the ratios of these biometric parameters to cerebellar diameter were similar to those of unaffected fetuses. Fetal weight was affected to a greater extent than the cerebellar diameter, leading to discordance between the two parameters. This discordance identified almost all asymmetrically growth-impaired fetuses with a sensitivity of 95.6% and specificity of 96.3%. In contrast, the ratio of head circumference to abdominal circumference remained normal in more than half of the fetuses. Fetal weight-to-cerebellar diameter discordance is a very sensitive and specific indicator of asymmetrical fetal growth impairment.

Biometry↗
PubMed1991

Cisplatin, carboplatin, and cyclophosphamide combination chemotherapy in advanced-stage ovarian carcinoma: an Eastern Cooperative Oncology Group pilot study.

Cyclophosphamide (CTX) 600 mg/m2, carboplatin 280 mg/m2, and cisplatin 50 mg/m2 were administered on day 1 every 4 weeks to 41 previously untreated ovarian cancer patients with residual disease greater than 2.0 cm after primary laparotomy. Of 22 patients with measurable disease treated with up to eight cycles of therapy, the overall clinical response rate was 73% (exact 95% confidence interval [CI], 50% to 89%), with 50% complete response (CR). Six of 11 clinical CR (cCR) patients underwent surgical restaging; three pathologic CRs (pCRs) and three pathologic partial responses (pPRs) with residual disease less than 2.0 cm were documented. Fourteen patients had nonmeasurable but assessable disease; the clinical response rate was 57% (Cl, 29% to 82%) with two (14%) CRs. Second-look surgery was performed in one of the two cCR patients; a pPR was documented. Five patients with nonassessable disease were stable during chemotherapy; two underwent surgery and had pCRs. The median time to treatment failure (TTF) was 14.8 months, and median survival for the 41 patients is 26.7 months. Overall, 37% of the patients had progression-free intervals of at least 2 years, and 27% have survival times in excess of 3 years. Hematologic toxicity was substantial but manageable, with 58% and 66% experiencing a granulocyte nadir less than 500/microL and a platelet nadir less than 50,000/microL, respectively. One treatment-associated fatality occurred as a result of leukopenic sepsis and renal failure in the setting of progressive disease and ureteral obstruction. Mild to moderate nausea and vomiting occurred in most patients, but none experienced severe ototoxicity or peripheral neuropathy. Over all courses, 73% of the projected dose intensity of CTX and carboplatin and 86% of cisplatin were delivered. Since granulocytopenia and thrombocytopenia were dose-limiting, the addition of colony-stimulating factors that support both myeloid and megakaryocyte precursors may permit further dose intensification.

Adenocarcinoma↗
PubMed1990

Infantile autism and Wernicke's encephalopathy.

In this paper I discuss evidence that brain damage in infantile autism may involve the same complex of brainstem nuclei that are damaged by alcohol abuse, thiamine deficiency, and asphyxia. These are metabolically the most active structures in the brain, which makes them vulnerable to many injurious factors. It is my belief that the high metabolic rate in the brainstem nuclei could support a control function for multiplexing of neural pathways, and that if this control is lost it may result in the defects of awareness and responsiveness seen in autistic children.

Asphyxia Neonatorum↗
PubMed1990

Uroporphyrinogen decarboxylase deficiency in hepatoerythropoietic porphyria: further evidence for genetic heterogeneity.

Catalytic and immunoreactive erythrocyte uroporphyrinogen decarboxylase was measured in a woman with hepatoerythropoietic porphyria (HEP). The uroporphyrinogen decarboxylase activity was 24% of the mean value for normal controls and the concentration of the immunoreactive enzyme (106 ng/mgHb), measured with the rocket immunoelectrophoresis technique, did not differ from that of healthy controls. Consequently, catalytically inactive, cross-reactive immunological material (CRIM) was present, and the patient was CRIM-positive. This enzyme activity and immunoreactive enzyme concentration differs from those for previously known HEP patients, and represents a new mutation, evidence for heterogeneity in inherited uroporphyrinogen decarboxylase deficiency.

Carboxy-Lyases↗
PubMed1989

Maternal-fetal transport of vitamin K1 and its effects on coagulation in premature infants.

We conducted a prospective study to determine (1) the maternal-fetal vitamin K1 transport in premature infants after vitamin K1 was given to the mothers antenatally and (2) the vitamin K1 effects on blood coagulation in the babies. Women in labor at less than or equal to 34 weeks of gestation were randomly selected to receive antenatal vitamin K1, 5 mg given intramuscularly (vitamin K1 group), or no vitamin K1 (control group). Eight infants, including one set of twins, were in the vitamin K1 group and six in the control group. Vitamin K1 concentrations were higher in the vitamin K1 group than in the control group (p = 0.06). Activated partial thromboplastin time was prolonged, and factor II coagulation activity and factor II antigen were proportionately decreased in cord plasma in both groups. The average ratio of factor II coagulation activity to antigen was not decreased in either group. Protein induced by vitamin K absence-II (PIVKA-II) was not detectable in any cord plasma sample in either group. These findings support previous reports that the decreased vitamin K-dependent coagulation activity in premature infants is the result of reduced synthesis of precursor proteins, rather than the result of vitamin K deficiency, and suggest that additional vitamin K1 is not likely to improve coagulation activity. Among those infants who underwent cranial ultrasonography, all four in the vitamin K1 group and one of five in the control group had mild intraventricular hemorrhage. Studies of a larger number of patients are necessary before it can be established that maternal antenatal administration of vitamin K1 results in improvement of coagulation and the prevention of intraventricular hemorrhage in premature infants.

Birth Weight↗
PubMed1989

[Solitary listerial abscess of the brain stem. Cure with antibiotic treatment].

A healthy 26-year-old man, without initially presenting fever, rapidly developed a focal right pontomedullary deficit associated with an aseptic lymphocytic meningitis. The diagnosis of Listeria infection was confirmed by blood cultures. CT and MRI demonstrated an abscess extending from the superior cerebellar peduncle to the lateral portion of the medulla. Immunological controls gave no indication of deficiency. With ampicillin therapy, started on the 5th day, clinical recovery was almost complete, but a soft palate right paresis persisted as the unique sequel. Antibiotic therapy was maintained for 5 months up to normal CSF and CT. One year after the onset, MRI was also normal. The rare nature of listerial abscess in the brainstem is discussed with regard to rhombencephalitides.

Adult↗
PubMed1989

[Coexistence of porphyria cutanea tarda and lupus erythematosus].

We report on the appearance of porphyria cutanea tarda in a patient with systemic LE and in two patients with discoid LE. A review is given on the corresponding literature. It is suggested that both lupus erythematosus and porphyria cutanea tarda have multifactorial inheritance. The cause of coexistence can be common genes responsible for the genetic determination which also predispose to the occurrence of both diseases. The question of etiology still remains obscure. This coexistence raises, however, a more practical question as regards the therapeutic modalities for the two diseases.

Adult↗
PubMed1988

Site of airway obstruction: effects on the acoustic impedance of excised pig lungs.

We investigated the relationship between the site of airway obstruction and the frequency dependence (FD) of lung acoustic impedance (ZL). The real (RL) and imaginary (XL) parts of ZL were measured by forced random noise in excised left pig lungs, before (base line) and after 1) no airway obstruction (controls, n = 10), 2) insufflation of 1-mm (B1, n = 5) or 2-mm (B2, n = 7) beads, and 3) partial reversible obstruction of lower lobar (LL) and then main-stem (MS) bronchus (n = 4). The beads caused both partial and total obstruction of airways with internal diameters of 2 mm (B1) and 2-6 mm (B2). Compared with base line, a negative FD of RL appeared from 4 to 10 Hz in LL, B1, and B2 obstructions. The FD of XL greater than 20 Hz increased in MS and LL obstruction exclusively and was the ZL feature that most clearly differentiated central from peripheral obstruction. In this experimental model, the anatomic limit distal from which obstruction no longer causes the "central" type of ZL change lies in airways with internal diameters notably greater than 2 mm.

Acoustic Impedance Tests↗
PubMed1987

[Analysis of factors related to early mortality in digestive hemorrhage caused by portal hypertension].

In order to determine immediate criteria of prognosis for patients with portal hypertension hospitalized for digestive hemorrhage, in an intensive care unit, 18 variables were recorded during the 24 hours following admission in 65 patients. Data related to death were age, ascites, hepatic encephalopathy, shock, active hemorrhage, acute pneumonia, decrease in prothrombin time, use of esophageal balloon tamponade, use of mechanical ventilation, number of red blood cell units transfused. Discriminant analysis yielded a linear combination of 4 variables which best separated survivors from non survivors with the following equation: F = 0.330 X hepatic encephalopathy + 0.433 X shock + 0.226 X active hemorrhage + 0.0097 X age - 0.396. The threshold decision of the hemorrhage prognosis index (HPI) was F = 0.57; 80 p 100 of all patients were correctly classified. In order to be validated, HPI was compared with a general (SAPS) and specific (Pugh's classification) scoring system, in a prospective study of 57 episodes of digestive hemorrhage. In this study, sensitivity was better with HPI than with SAPS (0.70 versus 0.45), specificity was higher with HPI than with Pugh's classification (0.86 versus 0.70). Percentage of correctly classified patients was higher using HPI (81 p. 100) than SAPS (77 p. 100) and Pugh's classification (68 p. 100). We suggest that the HPI, determined with 4 easily defined and recorded variables should be used prospectively to compare efficacy of different treatments.

Adult↗