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Biomedical subjects

J Cohen

Publications and source records attributed to J Cohen.

At least 649 records · Page 36Linked to original sources
PubMed1995

The use of first polar bodies for preimplantation diagnosis of aneuploidy.

A large proportion of patients undergoing in-vitro fertilization (IVF) are aged > or = 35 years. It has been estimated that in this age group, 50% of embryos are chromosomally abnormal, with aneuploidy being the major contributing factor. Since the origin of most aneuploidies is maternal meiosis I non-disjunction, unfertilized oocytes could be safely screened for aneuploidy by analysing their first polar bodies. To determine the feasibility of first polar body aneuploidy analysis, polar bodies were analyzed by fluorescence in-situ hybridization (FISH) using probes simultaneously for chromosomes X, Y, 18, 13/21 or X, Y, 18 and 16. Within 6 h of retrieval, 88% showed a normal segregation involving a single chromosome of each kind, with double-dotted hybridization signals, corresponding to dyads (chromosomes in metaphase I composed of two chromatids). The rest showed non-disjunction of full dyads (6%), or an unbalanced pre-division of dyads (6%), which gives a segregation of one chromatid or one dyad and a chromatid with the first polar body. But only 34% of polar bodies analysed 24 h after retrieval or later showed a normal segregation, with most of the other polar bodies showing balanced pre-division, with two separated hybridization signals for all the chromosomes analysed. The rates of non-disjunction and unbalanced pre-division after > or = 24 h in culture were similar to the rates in fresh oocytes. When both types of aneuploidy were considered together, an increase of aneuploidy with maternal age was detected, which although slight, was significant (P = 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Male and female genomes associated in a single pronucleus in human zygotes.

The ploidy of single-pronucleated human zygotes obtained after conventional in vitro fertilization was determined by fluorescent in situ hybridization (FISH) using multiple simultaneous probes for gonosomes and autosomes. After zona removal the single-pronucleated zygotes were exposed to cytochalasin B, and the pronucleus, surrounded by scant cytoplasm and the plasma membrane (karyoplast), was divided from the rest of the egg (cytoplast). The karyoplasts and the corresponding cytoplasts were analyzed separately by FISH. Of the 16 zygotes analyzed, 10 had haploid pronuclei and 6 were diploid. Four diploid pronuclei contained XY chromosomes, and 2 contained XX chromosomes. These results suggest that during the course of their interaction, human gamete nuclei can associate together and form diploid, single-pronucleated zygotes. These findings confirm a newly recognized variation of human pronuclear interaction during syngamy.

Cell Nucleus↗
PubMed1995

Formation of male pronuclei in partitioned human oocytes.

Ninety-five metaphase II human oocytes, aged in vitro for either one day or for two days, and five fresh immature oocytes with no visible germinal vesicle nucleus were partitioned into small cytoplasts after removal of the zona pellucida and exposure to cytochalasin B. Seventy-one metaphase II and four immature oocytes were used as intact zona-free controls. The cytoplasts derived from each partitioned oocyte and all the zona-free whole oocytes were exposed to normal or subfertile donor sperm and later assessed for signs of male pronucleus development. A total of 711 fragments (an average of 8 fragments per partitioned egg) with a mean diameter of about 50 microns were produced from the 100 partitioned oocytes. When exposed to normal sperm, 76% of the 1-day-old metaphase II fragments, 67% of the 2-day-old metaphase II fragments, and 83% of the immature oocyte fragments were fertilized. The mean number of decondensing nuclei per partitioned oocyte was 11.9 for the 1-day-old metaphase II oocytes, 6.4 for the 2-day-old metaphase II oocytes, and 13 for the immature oocytes. The mean number of decondensing nuclei per a whole zona-free oocyte was 5.6 for the 1-day-old metaphase II oocytes (p < 0.05), 6.7 for the 2-day-old metaphase II oocytes (NS), and 13 for the immature oocytes. When exposed to subfertile sperm, 54% of the 1-day-old metaphase II fragments and 28% of the 2-day-old metaphase II fragments were fertilized.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Nucleus↗
PubMed1995

Enhancement of fertilization by micromanipulation.

Micromanipulation techniques have been successfully applied to human gametes to assist fertilization when normal function is impaired. The past few years have witnessed the rapid evolution and clinical incorporation of this technology. The unprecedented efficiency of intracytoplasmic sperm injection far surpasses all previous methods. This method has thus become the best treatment option for many forms of male infertility.

Adult↗
PubMed1995

Fulminant head and neck congestion in advanced cutaneous T cell lymphoma: a poor prognostic indicator.

BACKGROUND: Clinical factors associated with a poor prognosis in patients with cutaneous T cell lymphoma (CTCL) include the extent and type of skin involvement and the presence and extent of lymphadenopathy. MATERIALS: We report retrospectively the clinical course and survival time of four patients with advanced CTCL after the development of fulminant head and neck congestion. METHODS: All four patients presented with marked erythema and edema of the head and neck with marked cervical adenopathy. Treatment with multidrug chemotherapy and radiation induced only brief remissions. The clinical picture was felt to be due to extensive tumor infiltration of the skin as well as lymphatic compression due to cervical adenopathy rather than venous compression at the level of the mediastinum. Survival from onset of this fulminant head and neck congestion was 1-5 months. CONCLUSION: Development of this fulminant head and neck congestion in patients with advanced CTCL heralds a progressively deteriorating clinical course with a poor prognosis.

Adult↗
PubMed1995

Sentence comprehension in multiple sclerosis.

INTRODUCTION: Explanations of sentence processing difficulty in aphasia have implicated slowed information processing speed. We tested this hypothesis by evaluating sentence comprehension in multiple sclerosis (MS), and relating comprehension performance to measures of information processing speed. MATERIAL & METHODS: Twenty right-handed, high school-educated, non-demented, native English speakers with clinically definite MS and 16 age- and education-matched control subjects were examined on 3 different sentence comprehension measures that stress grammatical appreciation. Performance was related to quantitative assessments of mental information processing speed. RESULTS: Group-wide analyses demonstrated a trend toward sentence comprehension difficulty in MS. Analyses of individual patient profiles identified a subgroup of MS patients who were consistently impaired to a significant extent across all sentence comprehension tasks. Their sentence comprehension difficulty was associated with selectively compromised mental information processing speed. CONCLUSION: Sentence comprehension difficulty in MS is associated with slowed information processing speed. This finding supports the claim that information processing speed contributes to sentence processing.

Adult↗
PubMed1995

Immunization with recombinant varicella-zoster virus expressing herpes simplex virus type 2 glycoprotein D reduces the severity of genital herpes in guinea pigs.

Varicella-zoster virus (VZV) is an attractive candidate for a live-virus vector for the delivery of foreign antigens. The Oka vaccine strain of VZV is safe and effective in humans, and recombinant Oka VZV (ROka) can be generated by transfecting cells with a set of overlapping cosmid DNAs. By this method, the herpes simplex virus type 2 (HSV-2) glycoprotein D (gD2) gene was inserted into an intergenic site in the unique short region of the Oka VZV genome. Expression of gD2 in cells infected with the recombinant Oka strain VZV (ROka-gD2) was confirmed by antibody staining of fixed cells and by immunoblot analysis. Immune electron microscopy demonstrated the presence of gD2 in the envelope of ROka-gD2 virions. The ability of ROka-gD2 to protect guinea pigs against HSV-2 challenge was assessed by inoculating animals with three doses of uninfected human fibroblasts, fibroblasts infected with ROka VZV, or fibroblasts infected with ROka-gD2. Neutralizing antibodies specific for HSV-2 developed in animals immunized with ROka-gD2. Forty days after the third inoculation, animals were challenged intravaginally with HSV-2. Inoculation of guinea pigs with ROka-gD2 significantly reduced the severity of primary HSV-2 infection (P < 0.001). These experiments demonstrate that the Oka strain of VZV can be used as a live virus vector to protect animals from disease with a heterologous virus.

Animals↗
PubMed1995

Doppler velocimetry of the fetal middle cerebral artery in patients with preterm labor and intact membranes.

A prospective cohort study was conducted to determine whether preterm labor is associated with changes in the impedance to blood flow of the fetal middle cerebral artery. Doppler velocimetry studies were performed in 194 consecutive patients with preterm labor and intact membranes. Pulsatility indices of the middle cerebral artery and umbilical artery were determined on admission. Results were expressed as ratio of the observed pulsatility index to mean value for gestational age expressed as delta MCA PI and delta UA PI, respectively. The prevalence of preterm delivery (< 37 weeks) and delivery within 24 hours of admission was 55.2% (107/194) and 15.5% (30/194), respectively. Patients with an examination-to-delivery interval within 24 hours had significantly lower mean delta MCA PI than that of patients delivered at > or = 37 weeks and > or = 4 weeks after the examination (P < 0.01). Fetuses with a delta MCA PI at or below 0.88 had a relative risk of 2 (95% confidence interval, 1.32 to 2.9) who were delivered within 24 hours compared to controls (sensitivity 76.7%, specificity 62.8%, positive predictive value 26.7%, negative predictive value 93.5%). Stepwise logistic regression analysis indicated that the relationship between delta MCA PI and examination-to-delivery interval remained statistically significant after correcting for cervical dilatation (P < 0.001). Our data indicate that preterm parturition is associated with a decrease in the impedance to flow in the fetal cerebral circulation.

Adult↗
PubMed1995

Soothing.

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Baths↗
PubMed1995

Embryo morphology, developmental rates, and maternal age are correlated with chromosome abnormalities.

OBJECTIVE: To determine some of the unresolved questions related to chromosome anomalies in early human embryos, such are the detection of any advanced maternal age effect; the complete assessment of mosaicism, which requires analysis of all cells; and the relationship with embryonic dysmorphism. Fluorescence in situ hybridization has been used in this study to answer these issues. DESIGN: Fluorescence in situ hybridization analysis of human embryos using simultaneously probes for three or five chromosomes. Five hundred twenty-four cleavage-stage human embryos obtained by IVF were analyzed by fluorescence in situ hybridization. Embryos were allocated into three groups according to morphological and developmental characteristics (arrested; slow and/or fragmented; morphologically and developmentally normal). The embryos also were analyzed according to maternal age. RESULTS: Dysmorphic embryos had higher rates of polyploidy and diploid mosaicism. Aneuploidy increased with maternal age in nonarrested embryos. Preimplantation genetic diagnosis successfully detected these abnormalities. CONCLUSION: This study demonstrates that, in morphologically and developmentally normal human embryos, cleavage-stage aneuploidy significantly increases with maternal age. The results suggest that implantation failure in older women largely could be due to aneuploidy.

Adult↗
PubMed1995

Viridans streptococcal bacteraemia: a clinical survey.

The occurrence of viridans streptococcal bacteraemia (VSB) in a London postgraduate teaching hospital was analysed retrospectively. Over a 30-month period, 39 patients with VSB were identified, and the clinical significance of VSB was assessed for each, based upon clinical and laboratory information. Endocarditis accounted for only 13% of the total patients with apparent VSB. A greater proportion of patients with VSB originated from the haematology unit (21%) and in particular, the bone-marrow transplantation unit (15%). VSB also occurred in patients with solid epithelial malignancies and in children aged < 12 months. Mortality associated with VSB was 7%. Viridans streptococci are emerging as important pathogens in previously unrecognized clinical settings, particularly hospitalized, immunocompromised patients.

Adolescent↗
PubMed1995

Pacific rim memories.

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Cultural Characteristics↗