American Heart Association Report on the Public Access Defibrillation Conference, December 8-10, 1994. American Heart Association Taskforce on Automatic External Defibrillation

Experimental conditions (pH 6.5, 24 h reaction, peptide:biotin ratio 1:5) were defined for preferential incorporation of the biotin molecule in the N-terminal alpha-amino group of peptides. This strategy could be helpful in numerous applications when an entire peptide chain must remain accessible for antibody or receptor binding. We illustrate this advantage in a solid-phase enzyme immunoassay designed to detect antibodies specific for bovine beta-lactoglobulin present in rabbit or human sera. This test involves synthetic peptides biotinylated in different positions and immobilized on a solid phase. The use of biotin/streptavidin interactions permitted more efficient detection of specific anti-peptide antibodies than solid phases prepared using conventional passive-adsorption techniques. The highest levels of antibody binding were measured when biotinylation occurred at the N-terminal extremity of immobilized peptides.     

Scannography apport in syringomyelic study. 40 syringolyelic cases (author's transl)

Forty patients with a syringomyelic syndrome were studied by means of scannography of the cervical spine and cervico-occipital joint before and after intrathecal injection of metrizamide. metrizamide transit, and more particularly the opacification of the syringomyelic cyst by metrizamide were assessed by delayed passages. This study demonstrates the value of this technique both from the morphological and dynamic point of view.     

Subfornical organ: forebrain site of pressor and dipsogenic action of angiotensin II

Intracranial injection of angiotensin II (AII) at three brain sites elicited near simultaneous dipsogenic and pressor effects in rats. Both effects were maximal, occurred with the shortest latencies, and at the lowest doses of AII when the cannula terminated precisely within the parenchyma of the subfornical organ (SFO). Pressor effects were produced by SFO injection of a dose of AII (0.1 pg) which approximates plasma AII concentrations at the high end of the physiological range. Both the drinking and pressor effects were blocked by saralasin. Injections of AII at sites immediately adjacent to SFO produced smaller effects with longer latencies. These results ruled out the possibility that SFO injections were effective via leakage to alternative sites. The pressor effect of AII at the SFO remained in animals under chloralose anesthesia, demonstrating that it is not an artifact of drinking behavior. These results indicate that the SFO is a site of AII pressor action, and confirm previous demonstrations that the structure is a site of AII drinking action.     

Evidence that physiologic levels of circulating estrogens and neonatal sex-imprinting modify postpubertal hepatic microsomal 3-hydroxy-3-methylglutaryl coenzyme A reductase activity

Intact, but sham-operated female rats had 2- to 3-fold higher levels of hepatic 3-hydroxy-3-methylglutaryl CoA reductase activity than their male counterparts (15--21.5 vs. 6.7--8.7 nmol mevalonate/mg protein per h). The activity of the hepatic enzyme declined to about the same relative degree (40--60%) in male and female rats that were gonadectomized after puberty (53 days of age) and killed 5 weeks later. Implantation of silastic capsules containing 17 beta-estradiol increased the level of hepatic 3-hydroxy-3-methylglutaryl CoA reductase to levels found in sham-operated controls. In rats that were gonadectomized in infancy (12 h old) and killed 7--8 weeks later, the level of enzyme activity was not altered in females, but it was increased from 60--240% in males. Consequently, following neonatal gonadectomy, male-female differences in enzyme activity were no longer apparent. Implantation of silastic capsules containing estradiol in neonatally gonadectomized rats resulted in a doubling of enzyme activity in both males and females. Ovariectomy reduced plasma estrogen levels, but implantation of estradiol in gonadectomized males and females increased the hormone level to that found in sham-operated females. Thus, the results strongly suggest a role for physiologic levels of estrogen as a positive effector of 3-hydroxy-3-methylglutaryl CoA reductase activity. Neonatal sex imprinting also appears to modulate the enzyme activity since sex-mediated differences are effaced by gonadectomy in infancy, but not by gonadectomy following puberty.     

Generalized equations for predicting body density of women

Previous research with women has shown that body composition regression equations derived from anthropometric variables were population specific. This study sought to derive generalized equations for women differing in age and body composition. The hydrostatic method was used to determine body density (BD) and percent fat (%F) on 249 women in 18 to 55 years (X = 31.4 +/- 10.8 yrs) and 4 to 44 %F (X = 24.1 +/-7.2 %F). Skinfold fat (S), gluteal circumference (C) and age were independent variables. The quadratic form of the sum of three, four and seven S in combination with age and gluteal C produced multiple correlations that ranged from 0.842 to 0.867 with standard errors of 3.6 to 3.8 %F. The equations were cross-validated on a different sample of 82 women with similar age and %F characteristics. The correlations between predicted and hydrostatically determined %F ranged from 0.815 to 0.820 with standard errors of 3.7 to 4.0 %F. This study showed that valid generalized body composition equations could be derived for women varying in age and body composition, but care need to be exercised with women over an age of forty.     

Interobserver variation in the evaluation of neurological signs: observer dependent factors

We have previously reported that polymorphonuclear granulocyte (PMN) and monocyte oxidative metabolism is reduced in polycythemia vera (PV) patients compared to healthy control subjects, after stimulation with cell surface receptor-dependent stimuli such as n-formyl-methionyl-leucyl-phenylalanine, leukotriene B4 and platelet-activating factor (PAF). In contrast, the oxidative response to phorbol myristate acetate (PMA) is normal. We now show that, in PV patients exhibiting significantly reduced PMN chemiluminescence after PAF stimulation, PAF induced platelet aggregation was also reduced--40 +/- 3% compared to 50 +/- 2% in controls (p < 0.01). The defective aggregatory response to PAF in PV remained over a wide range of stimuli concentrations. Platelet aggregation induced by PMA and ADP, however, was similar in PV and controls. In contrast, platelet aggregation induced by PAF (or by ADP and PMA) was not significantly reduced in patients with chronic myeloid leukemia, essential thrombocythemia and multiple myeloma. Furthermore, the release of beta-thromboglobulin was slightly but not significantly higher after PAF stimulation in PV and this argues against an abnormal PAF receptor as the cause of the defective function. Thus, not only PV neutrophils, but also PV platelets show a discrete defect of the stimulus response coupling for PAF, indicating a disease-specific abnormality that appears to be of clonal origin.     

A functional analysis of imprinting in parthenogenetic embryonic stem cells

A detailed analysis of the developmental potential of parthenogenetic embryonic stem cells (PGES) was made in vivo and in vitro, and a comparison was made with the development of cells from parthenogenetic embryos (PG). In vivo, in chimeras with normal host cells (N), PGES cells showed a restricted tissue distribution consistent with that of PG cells, suggesting faithful imprinting in PGES cells with respect to genes involved in lineage allocation and differentiation. Restricted developmental potential was also observed in teratomas formed by ectopic transfer under the kidney capsule. In contrast, the classic phenotype of growth retardation normally observed in PG<==>N chimeras was not seen, suggesting aberrant regulation in PGES cells of genes involved in growth regulation. We also analysed the expression of known imprinted genes after ES cell differentiation. Igf2, H19 and Igf2r were all appropriately expressed in the PGES derived cells following induction of differentiation in vitro with all-trans retinoic acid or DMSO, when compared with control (D3) and androgenetic ES cells (AGES). Interestingly, H19 was found to be expressed at high levels following differentiation of the AGES cells. Due to the unexpected normal growth regulation of PGES<==>N chimeras we also examined Igf2 expression in PGES derived cells differentiated in vivo and found that this gene was still repressed. Our studies show that PGES cells provide a valuable in vitro model system to study the effects of imprinting on cell differentiation and they also provide invaluable material for extensive molecular studies on imprinted genes. In addition, the aberrant growth phenotype observed in chimeras has implications for mechanisms that regulate the somatic establishment and maintenance of some imprints. This is of particular interest as aberrant imprinting has recently been invoked in the etiology of some human diseases.     

The regulation of membrane 125I- and 86Rb+ permeability in a virally transformed cell line (NCL-SG3) derived from the human sweat gland epithelium

We have explored the factors that may regulate membrane permeability in a cell line (NCL-SG3) derived from the human sweat gland epithelium. Ionomycin increased the rate of 125I-efflux from preloaded cells and this action appeared to be due to an increase in intracellular free calcium ([Ca2+]i). The ionomycin-evoked increase in 125I- efflux was reduced in cells that were exposed either to barium or to valinomycin in the presence of a high concentration of external potassium. It thus appears that a fraction of the ionomycin-evoked increase in 125I- efflux is due to the activation of potassium channels and experiments using 86Rb+ also suggested that ionomycin increased the rate of potassium efflux, an effect which was totally abolished by barium. Blockade of Na(+)-K(+)-2Cl- cotransport and of Cl- -HCO3- exchange reduced the basal rate of 125I- efflux and the ionomycin-evoked increase in 125I-efflux from control cells and from cells depolarized by valinomycin. These transport systems thus contribute to anion efflux, although [Ca2+]i-dependent chloride channels also appear to be present. Acetylcholine increases [Ca2+]i in the secretory cells of human sweat glands, but this neurotransmitter did not increase [Ca2+]i in NCL-SG3 cells and so membrane permeability was not under cholinergic control. Adrenaline did not increase [Ca2+]i, but this hormone did evoke cyclic-3',5'-adenosine monophosphate (cyclic AMP) production. However, membrane permeability was not under adrenergic control, as the cells did not appear to express functional, cyclic AMP-dependent anion channels. This may be because they were not fully differentiated under the culture conditions. ATP consistently evoked a dose-dependent increase in anion efflux that appeared to be mediated by [Ca2+]i. The increase in [Ca2+]i was initiated by the release of calcium from a limited internal store and was subsequently sustained by calcium influx. UTP and ADP also increased [Ca2+]i, whereas adenosine, AMP and alpha,beta-methylene ATP were without effect. These data thus suggest that a subclass of type 2 purine receptor, which is functionally coupled to phosphoinositidase C, is present in these cells.     

Chronic intussusception in children: report of one case

Chronic intussusception is defined as intussusception lasting for 14 days or more. Because the clinical manifestation is different from that of acute intussusception, the diagnosis is usually delayed or missed. Ultrasonography is of diagnostic value. We present a 8-year-old boy who had the complaints of marked body weight loss and intermittent abdominal pain for one month. Hydrostatic reduction failed in this case. Laparotomy revealed an ileo-colic intussusception, the leading point of which was a colonic polyp. We would like to emphasize that chronic intussusception frequently appears a nonacute abdominal condition, usually intermittent abdominal pain, and sometimes marked body weight loss and an abdominal mass. Surgical intervention is usually needed in older children because a high incidence of underlying lesions in them.     

Digital mammography: M-channel quadrature mirror filters (QMFs) for microcalcification extraction

Multiresolution methods are reported for feature extraction in breast cancer screening using digital mammography. The initial application is directed at the detection of microcalcification clusters (MCCs). Quadrature mirror filter (QMF) banks, using both two and three channel are proposed for the first time for both multiresolution decomposition and reconstruction. These filters are specifically tailored for automatic extraction of MCCs. The QMF multiresolution methods are compared to two channel tree structured wavelet transforms (TSWTs) methods previously reported. The QMF filters are preceded by an advanced tree structured nonlinear filter for noise suppression, prior to feature extraction, in order to minimize the false positive (FP) detection rate in digital mammography. The relative performance of these methods were evaluated using both simulated images and fifteen representative digitized mammograms containing biopsy proven microcalcification clusters. Similar high sensitivity (true positive (TP) detection rate (100%) and high specificity (0.6 average false positive (FP) MCC's/image) were observed, substantially better than more traditional approaches using single scale filters. The three channel QMF method, however, demonstrated better detail preservation of MCC's extracted compared to the two channel method. Detail preservation is important for the characterization of MCC's or individual microcalcifications in cancer screening.