Nonrandom nature of in vivo methylation of dimethylnitrosamine and the subsequent removal of methylated products from rat liver chromatin DNA.

This investigation was designed to study whether methylation of liver chromatin DNA by dimethylnitrosamine (DMN) and the subsequent in vivo removal of DNA-bound methylated products are random. Liver chromatin DNA was fractionated into nuclease-digestible and nondigestible material 4 hr following the administration of [3H]DMN (0.5 mg/250 muCi/100 g body weight). Digestion of such methylated liver chromatin with pancreatic DNase I or micrococcal nuclease and analysis of nuclease-digested acid-soluble products revealed a discrepancy between the radioactivity released (72%) and the nucleotides released (50%) as measured by the absorbance at 260 nm. This discrepancy disappeared, and the rate and extent of release of both the radioactivity and the absorbance at 260 nm were identical when the total purified DNA isolated from methylated chromatin was used as the substrate instead of chromatin DNA in the nuclease reaction. These results, together with the fact that guanine contents of the DNA of the two fractions of the chromatin isolated by nuclease digestion were identical, suggest that methylation of the nuclease-accessible region of hepatic chromatin DNA is relatively greater than that of the inaccessible region. The study of the removal of methylated products in the accessible region of the chromatin DNA further reveals that, of the methylated products present at 4 hr, 62% is lost by 3 days, 87% is lost by 1 week and 94% is lost by 2 weeks. However, loss from the nuclease-inaccessible region of chromatin DNA is only 27% by 3 days, 49% by 1 week, and 86% by 2 weeks, thereby suggesting that the removal of methylated products from this region of chromatin DNA is relatively slower compared with that from the nuclease-accessible region of chromatin-DNA. The results of this study thus indicated (a) an increased methylation and faster rate of removal of DMN-induced methylated products in nuclease-accessible regions of chromatin DNA and (b) decreased methylation and slower rate of removal from the nuclease-inaccessible regions of chromatin DNA. It is concluded that the distribution and removal of DMN-induced methylated products in liver chromatin DNA is nonrandom as measured by this technique.     

Modified histologic technique for processing metallic coil-bearing tissue

We developed a modified paraffin-embedding histologic technique for processing metallic coil-bearing aneurysm tissues. This modified technique was successfully employed for processing platinum coil-bearing tissue for 30 rabbit aneurysms and 6 swine aneurysms. This technique for sectioning coil-bearing aneurysms resulted in little or no tissue distortion and permitted good preservation of morphology and application of multiple advanced staining techniques. This technique is considered beneficial for studying the molecular mechanisms of aneurysm healing after coiling.     

Neural classification of lung sounds using wavelet coefficients

Electronic auscultation is an efficient technique to evaluate the condition of respiratory system using lung sounds. As lung sound signals are non-stationary, the conventional method of frequency analysis is not highly successful in diagnostic classification. This paper deals with a novel method of analysis of lung sound signals using wavelet transform, and classification using artificial neural network (ANN). Lung sound signals were decomposed into the frequency subbands using wavelet transform and a set of statistical features was extracted from the subbands to represent the distribution of wavelet coefficients. An ANN based system, trained using the resilient back propagation algorithm, was implemented to classify the lung sounds to one of the six categories: normal, wheeze, crackle, squawk, stridor, or rhonchus.     

A randomized, multicenter masked comparison trial of poractant alfa (Curosurf) versus beractant (Survanta) in the treatment of respiratory distress syndrome in preterm infants

We compared the onset of clinical response and safety of two surfactants, poractant alfa (Curosurf, Chiesi Pharmaceuticals, Parma, Italy) and beractant (Survanta, Ross Laboratories, Columbus, OH), for treatment of respiratory distress syndrome (RDS) in preterm infants weighing 750 to 1750 g at birth and <35 weeks gestation. The study was performed as a 20-center prospective, randomized, masked comparison trial. Preterm infants (n = 293) with RDS were randomized to receive an initial dose of either 100 (n = 96) or 200 (n = 99) mg/kg of poractant alfa or 100 ( n = 98) mg/kg of beractant. All repeat dosing was given at 100 mg/kg. The onset of clinical response after the first dose was studied by comparing changes in the fraction of inspired oxygen (F IO(2)) between 0 and 6 hours measured using the area under the curve (F IO(2) AUC (0-6)); other outcomes were assessed for the entire cohort at 28 days and for infants born at < or = 32 weeks gestation at 36 weeks postconceptional age. We found that the mean F IO(2) AUC (0-6) values for the 100 and 200 mg/kg poractant alfa groups were both significantly lower than the mean F IO(2) AUC (0-6) values for the beractant group ( p < 0.005) but were not different from each other. Other outcomes were not different among the three groups for the entire cohort, but in infants born at < or = 32 weeks gestation, mortality up to 36 weeks postconceptional age was significantly less in the 200 mg/kg poractant alfa group than in either the beractant group (3% versus 11%; p = 0.034) or in the 100 mg/kg poractant alfa group (3% versus 11%; p = 0.046). Need for more than one dose of surfactant was significantly lower in infants treated with an initial dose of 200 mg/kg poractant alfa in comparison to the beractant-treated group ( p < 0.002). Treatment with poractant alfa (200 mg/kg initial dose) resulted in rapid reduction in supplemental oxygen with fewer additional doses of surfactant versus treatment with beractant in infants <35 weeks gestation with RDS, and significantly reduced mortality ( p <0.05) than either beractant or poractant alfa (100 mg/kg dosing) in infants < or =32 weeks gestation with RDS.     

Regulation of the immune system by SOCS family adaptor proteins

Signal transduction via cytokine receptors is regulated by several mechanisms that control initiation, magnitude and duration of the signaling pathways. Cytokine-induced SOCS family adaptors function as feedback inhibitors of cytokine receptor signaling by inhibiting the JAK-STAT signal transduction pathway. Specific gene-targeted mice have unveiled critical, non-overlapping functions for SOCS1 and SOCS3 in lymphocyte development and homeostasis, and in the regulation of macrophage and dendritic cell functions. In this review, we will discuss the structure of SOCS proteins, mechanisms by which they control the JAK-STAT pathway and their role in immune regulation.     

Metabolism and DNA binding studies of 4-hydroxyestradiol and estradiol-3,4-quinone in vitro and in female ACI rat mammary gland in vivo

Studies of estrogen metabolism, formation of DNA adducts, carcinogenicity, cell transformation and mutagenicity have led to the hypothesis that reaction of certain estrogen metabolites, predominantly catechol estrogen-3,4-quinones, with DNA can generate the critical mutations initiating breast, prostate and other cancers. The endogenous estrogens estrone (E1) and estradiol (E2) are oxidized to catechol estrogens (CE), 2- and 4-hydroxylated estrogens, which can be further oxidized to CE quinones. To determine possible DNA adducts of E1(E2)-3,4-quinones [E1(E2)-3,4-Q], we reported previously that the reaction of E1(E2)-3,4-Q with dG produces the depurinating adduct 4-hydroxyE1(E2)-1-N7Gua [4-OHE1(E2)-1-N7Gua] by 1,4-Michael addition (Stack et al., Chem. Res. Toxicol., 1996, 9, 851). We report here that reaction of E1(E2)-3,4-Q with Ade results in the formation of 4-OHE1(E2)-1-N3Ade by 1,4-Michael addition. The N7Gua and N3Ade depurinating adducts formed both in vitro and in rat mammary gland in vivo were analyzed by HPLC with electrochemical detection and, for some samples, by LC/MS/MS. When E2-3,4-Q was reacted with DNA in vitro, the depurinating adducts 4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua, which are rapidly lost from DNA by cleavage of the glycosyl bond, were formed (>99% of the total adducts), as well as traces of stable adducts, which remain in DNA unless removed by repair. Similar results were obtained when 4-OHE2 was oxidized by horseradish peroxidase, lactoperoxidase, tyrosinase or phenobarbital-induced rat liver microsomes in the presence of DNA. When 4-OHE2 or E2-3,4-Q was injected into the mammary glands of female ACI rats in vivo and the mammary tissue was excised 1 h later, the depurinating adducts 4-OHE2-1-N3Ade and 4-OHE2-1-N7Gua constituted >99% of the total adducts formed. In addition, 4-OHE2 conjugates formed by reaction of E2-3,4-Q with glutathione were also detected. These results demonstrate that the 4-CE are metabolized to CE-3,4-Q, which react with DNA to form primarily depurinating adducts. These adducts can generate the critical mutations that initiate cancer (Chakravarti et al., Oncogene, 2001, 20, 7945; Chakravarti et al., Proc. Am. Assoc. Cancer Res., 2003, 44, 180).     

Surgical results of posterior fossa decompression for patients with Chiari I malformation

Introduction An increasing number of children with Chiari I malformations are coming to the attention of neurosurgeons today, although a consensus on the surgical approach to these lesions has yet to be found.Methods We present a retrospective analysis of posterior fossa decompression (PFD) performed at our institution on 96 patients from 1989 to 2001. Statistical analyses based on clinical and radiographic presentation and the types of surgical procedures used formed the basis for our review.Results Most of the patients with hydromyelia underwent duraplasty procedures with or without tonsillar manipulation. In contrast, most patients without hydromyelia underwent bony decompression with dural scoring and intraoperative ultrasound. PFD with bony decompression and dural scoring showed a 72% success rate, compared with 68% for duraplasty. Dural opening was not more likely to improve or arrest hydromyelia. The group subjected to duraplasty, however, had a significantly higher complication rate. Patients under the age of 8 fared better than their older counterparts.Conclusions Overall, we favor a tailored posterior fossa craniectomy with dural scoring as the initial surgical procedure in children with Chiari I malformation with or without a syrinx. This less invasive approach minimizes complications associated with dural opening and offers comparable success rates.     

Sperm chromosomal abnormalities are linked to sperm morphologic deformities

OBJECTIVE: To describe the association between specific sperm morphologic abnormalities and sperm chromosomal abnormalities on multicolor interphase fluorescence in situ hybridization (FISH). DESIGN: Case report.Reproductive medicine unit in a tertiary referral center. PATIENT(S): Three infertile men with severe oligoasthenospermia and total teratozoospermia who were referred for IVF treatment. MAIN OUTCOME MEASURE(S): Incidence of spermatozoal chromosomal aneuploidy for chromosome 18 and the sex chromosomes by using FISH. RESULT(S): Morphologic assessment of sperm revealed a high incidence of double heads, multinucleated sperm heads, and multiple tails. Hormone profiles and karyotyping of peripheral lymphocytes were normal in the three men. The proportion of sperm with disomy, trisomy and tetrasomy for chromosome 18, and the sex chromosomes in each patient was 100%, 76%, and 82.5%, respectively. CONCLUSION(S): Specific morphologic abnormalities of sperm may be associated with higher incidence of chromosomal abnormalities. Resolving infertility by offering patients in vitro fertilization/intracytoplasmic sperm injection must be approached with caution because of the significant risk for embryonic aneuploidy and chromosomal abnormalities in any subsequent offspring.