Pulsed field gel electrophoresis on single murine hemopoietic colonies

We report a technique which allows for the direct molecular analysis of single whole murine hemopoietic colonies by pulsed field gel electrophoresis (PFGE). Murine bone marrow cells were plated out in semi-solid agarose and gave rise to macroscopic colonies after 11 days in culture. Single colonies were excised from the agarose using a sterile blade and embedded without further manipulation in molten low-melting-temperature agarose. The leucocyte DNA contained within the agarose plug was subjected to restriction enzyme digestion and PFGE. Sufficient high molecular weight DNA is afforded by this method to achieve a hybridization signal with a single copy probe. This method will make PFGE directly applicable to the clonal analysis of chromosomal aberrations in hemopoietic stem and progenitor cells.

Developmental trends in the interaction between auditory and linguistic processing

The developmental course of multidimensional speech processing was examined in 80 children between 3 and 6 years of age and in 60 adults between 20 and 86 years of age. Processing interactions were assessed with a speeded classification task (Garner, 1974a), which required the subjects to attend selectively to the voice dimension while ignoring the linguistic dimension, and vice versa. The children and adults exhibited both similarities and differences in the patterns of processing dependencies. For all ages, performance for each dimension was slower in the presence of variation in the irrelevant dimension; irrelevant variation in the voice dimension disrupted performance more than irrelevant variation in the linguistic dimension. Trends in the degree of interference, on the other hand, showed significant differences between dimensions as a function of age. Whereas the degree of interference for the voice-dimension-relevant did not show significant age-related change, the degree of interference for the word-dimension-relevant declined significantly with age in a linear as well as a quadratic manner. A major age-related change in the relation between dimensions was that word processing, relative to voice-gender processing, required significantly more time in the children than in the adults. Overall, the developmental course characterizing multidimensional speech processing evidenced more pronounced change when the linguistic dimension, rather than the voice dimension, was relevant.

Predicting mortality risk for infants weighing 501 to 1500 grams at birth: a National Institutes of Health Neonatal Research Network report

OBJECTIVES

To develop and evaluate a model that predicts mortality risk based on admission data for infants weighing 501 to 1500 grams at birth, and to use the model to identify neonatal ICUs where the observed mortality rate differs significantly from the predicted rate.

DESIGN

Validation cohort study.

SETTING

University-based, tertiary care neonatal ICUs.

PATIENTS

Sample of 3,603 infants with birth weights of 501 to 1500 grams who were born at seven National Institute of Child Health and Human Development (NICHHD) Neonatal Research Network Centers, over a 2-yr period of time.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Based on logistic regression analysis, admission factors associated with mortality risk for inborn infants were: decreasing birth weight, appropriate size for gestational age, male gender, non-black race, and 1-min Apgar score of < or = 3. The mortality prediction model based on these factors had a sensitivity of 0.50, a specificity of 0.92, a correct classification rate of 0.82, and an area under the receiver operating characteristic curve of 0.82 when applied to a validation sample. Goodness-of-fit testing showed that there was a marginal degree of fit between the observations and model predictions (chi 2 = 15.4, p = .06). The observed mortality rate for 3,603 infants at the seven centers was 24.7%, ranging from 21.8% to 27.7% at individual centers. There were no statistically significant differences between observed and predicted mortality rates at any of the centers. One center had an observed mortality rate that was 2.8% lower than predicted by the model (95% confidence interval -6.0% to 0.5%), and another center had an observed rate that was 3% higher than expected (95% confidence interval -0.3% to 6.2%).

CONCLUSIONS

Mortality risk for infants weighing 501 to 1500 grams can be predicted based on admission factors. However, until more accurate predictive models are developed and validated and the relationships between care practices and outcomes are better understood, such models should not be relied on for evaluating the quality of care provided in different neonatal ICUs.

A photometric study of the effect of pupil dilatation on Nd:YAG laser iridotomy area

A photometric study of the effect of pupil dilatation on Nd:YAG laser iridotomy area was performed in 21 eyes of 21 patients. The iridotomy area was 0.075 (0.055) mm-2 (mean (SD)) before pupil dilatation and 0.073 (0.070) mm-2 after pupil dilatation (t test NS). Iridotomy area after pupil dilatation correlated with iridotomy area before pupil dilatation (r = 0.815, p < 0.01) but did not significantly correlate with measures of iridotomy shape or position, or with changed iris area following pupil dilatation. Two iridotomies became reduced to less than 20% of their initial area following pupil dilatation. Our findings suggest that the only effective method of avoiding development of unacceptably small iridotomy area after pupil dilatation is to create a sufficiently large iridotomy at the time of initial laser surgery.

Cryotherapy for retinopathy of prematurity in a regional neonatal intensive care unit

Ninety-six low birth-weight premature infants at risk of retinopathy of prematurity (ROP) were screened over a 25-month period, yielding 30 eyes of 15 infants with 'treatable' disease. The response and complications of cryotherapy were prospectively evaluated in these infants over a 3-24-month period. Six eyes of three infants progressed to cicatricial disease despite treatment. One infant developed angle closure glaucoma but neither eye showed cicatricial disease. In 24 eyes of 12 infants regression of active ROP was observed after treatment. The local and systemic complications associated with cryotherapy are discussed.

Argon laser pretreatment 4 to 6 weeks before Nd:YAG laser iridotomy

Argon laser pretreatment followed by Nd:YAG laser iridotomy 4 to 6 weeks later was performed in the right eye of 10 patients. Primary Nd:YAG laser iridotomy was performed in the left eye. Significantly more Nd:YAG laser energy was needed to produce an iridotomy in pretreated eyes (P less than .001). Pretreated eyes developed a significantly larger pigment epithelium defect around the iridotomy site and a greater degree of pigmentation of the inferior part of the trabecular meshwork 6 months following treatment. Argon laser pretreatment followed by Nd:YAG laser iridotomy 4 to 6 weeks later appears to offer no advantages over primary Nd:YAG laser iridotomy.

Aerosol ventilation scintigraphy in the evaluation of bronchopleural fistula: a case report and literature review

Radioaerosol scanning is simple to perform and is widely used in conjunction with perfusion imaging to detect pulmonary emboli. It may also be a valuable tool for the early diagnosis of postpneumonectomy bronchopleural fistula. The authors present an illustrative case in which radioactive aerosol imaging was used to confirm a bronchopleural fistula secondary to pneumonectomy for squamous cell carcinoma.

Very low birth weight outcomes of the National Institute of Child Health and Human Development Neonatal Network

This report describes the neonatal outcomes of 1765 very low birth weight (less than 1500 g) infants delivered from November 1987 through October 1988 at the seven participating centers of the National Institute of Child Health and Human Development Neonatal Intensive Care Network. Survival was 34% at less than 751 g birth weight (range between centers 20% to 55%), 66% at 751 through 1000 g (range 42% to 75%), 87% at 1001 through 1250 g (range 84% to 91%), and 93% at 1251 through 1500 g (range 89% to 98%). By obstetric measures of gestation, survival was 23% at 23 weeks (range 0% to 33%), 34% at 24 weeks (range 10% to 57%), and 54% at 25 weeks (range 30% to 72%). Neonatal morbidity included respiratory distress (67%), symptomatic patent ductus arteriosus (25%), necrotizing enterocolitis (6%), septicemia (17%), meningitis (2%), urinary tract infection (4%), and intraventricular hemorrhage (45%, 18% grade III and IV). Morbidity increased with decreasing birth weight. Oxygen was administered for greater than or equal to 28 days to 79% of less than 751-g birth weight infants (range between centers 67% to 100%), 45% of 751- through 1000-g infants (range 20% to 68%), and 13% of 1001- through 1500-g infants (range 5% to 23%). Ventilator support for greater than or equal to 28 days was given to 68% of infants at less than 751 g, 29% at 751 through 1000 g, and 4% at greater than 1000 g. Hospital stay was 59 days for survivors vs 15 days for infants who died. Sixty-nine percent of survivors had subnormal (less than 10th percentile) weight at discharge. The data demonstrate important intercenter variation of current neonatal outcomes, as well as differences in philosophy of care and definition and prevalence of morbidity.

The effect of cesarean delivery on birth outcome in very low birth weight infants. National Institute of Child Health and Human Development Neonatal Research Network

To determine whether cesarean delivery is associated with a better outcome than vaginal delivery for infants weighing less than 1500 g (very low birth weight), we examined neonatal mortality and the incidence of intraventricular hemorrhage (IVH) in 1765 very low birth weight inborn infants admitted to seven neonatal intensive care centers. The cesarean rate was 32.5% for infants weighing 501-750 g and 52.4% for infants weighing 751-1000 g. The neonatal death rate was 53.1% for infants weighing 501-750 g delivered by cesarean, compared with 64.3% for vaginally born infants (P = .046). However, for infants weighing 1001-1250 g, the neonatal death rate for infants delivered by cesarean was 14.4%, compared with 7.8% for infants born vaginally (P = .02). The incidence of IVH was significantly lower in infants born by cesarean than in those born vaginally only in the 1251-1500-g birth weight interval (11.8 versus 18.9%; P = .03). Compared with women delivering vaginally, those delivered by cesarean were more likely to attain a higher mean gestation, to have preeclampsia, and to have a breech presentation, and less likely to be in labor. After adjusting by logistic regression for gestational age, preeclampsia, breech presentation, presence or absence of labor, and for center effects, the odds ratio for neonatal death was 1.00 (95% confidence interval 0.71-1.41); for IVH, the odds ratio was 0.85 (95% confidence interval 0.61-1.19). These data suggest that after accounting for certain maternal and fetal factors, cesarean delivery is not associated with a lower risk of either mortality or IVH.

Coordination of trophic interactions by separate developmental programs in sensory neurons and their target fields

In the developing vertebrate nervous system the survival of sensory neurons becomes dependent on neurotrophic factors when their axons reach their target fields, and the synthesis of nerve growth factor (NGF) by target field cells commences with the arrival of the earliest axons. The timing of NGF synthesis and the onset of neurotrophic factor dependence are not, however, reliant on innervation. NGF synthesis occurs on time in developing target fields in which innervation is prevented, and sensory neurons cultured before innervating their targets become dependent on neurotrophic factors for survival after a certain length of time in culture. The length of time neurons survive in culture before becoming neurotrophic factor-dependent is related to the time they would normally contact their targets in vivo: populations of neurons that have nearby targets which are innervated early respond to neurotrophic factors before neurons that have more distant targets which are innervated later. The timing of target field innervation is governed not only by the distance axons have to grow but by the rate at which they grow. Axonal growth rate is also regulated in accordance with target distance: neurons with distant targets extend axons faster than neurons with nearby targets. In addition to reviewing evidence for separate developmental programs that control the timing of neurotrophic factor synthesis in the target field and the onset of neurotrophic factor dependence in early sensory neurons, we will consider the mechanisms that might play a role in regulating the survival of neurons during the phase of neurotrophic factor independence.

Hematopoietic stem cell- and marrow stromal cell-specific requirements for gamma irradiation leukemogenesis in vitro

The hematopoietic and stromal cell-specific properties of the cells involved in gamma irradiation leukemogenesis in vitro were defined. Cocultivation of clonal factor-dependent (FD), interleukin 3 (IL-3)-dependent cell lines 32D cl 3 or B6SUtA, or dual IL-3-/granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent cell lines FDC-P1 or bg/bg d64 was carried out with clonal stromal cell lines D2XRII, GB1/6, +/+ 2.4, or Sld3. FD cell lines were added to control or 5000-cGy-irradiated plateau phase monolayer cultures of each stromal cell line, and parameters of stem cell engraftment and malignant transformation in vitro were quantitated. Cobblestone island formation by FD cells, cumulative production of nonadherent hematopoietic cells, and evolution of tumorigenic factor-independent (FI) subclonal lines were quantitated over 5-8 weeks. There was no detectable evolution of FI sublines with 32D cl 3, B6SUtA, or bg/bg d64 cells cocultivated with control or irradiated Sld3 stromal cells. IL-3-dependent cell lines 32D cl 3 or B6SUtA formed small 10- to 49-cell cobblestone "clusters" at low frequency on control or irradiated D2XRII, showed limited proliferation for less than 1 week, and showed no detectable evolution of FI cell lines. Subclones of 32D cl 3 derived by transfection and expression of recombinant oncogenes v-sis, or c-myc, or the epidermal growth factor receptor remained factor dependent and did not transform to factor independence after cocultivation with irradiated stromal cell lines. In contrast, cell line bg/bg d64, and each of seven subclonal lines of FDC-P1, including subclones selected for growth in GM-CSF, formed abundant cobblestone island colonies of greater than or equal to 50 cells on irradiated D2XRII stromal cells, produced non-adherent cells over 5-8 weeks, and showed evolution of tumorigenic FI subclonal lines. The data provide evidence for stable biological differences in both the hematopoietic and stromal cell components of the in vitro model of gamma irradiation leukemogenesis.

The scurfy mouse mutant has previously unrecognized hematological abnormalities and resembles Wiskott-Aldrich syndrome

The X chromosome-linked scurfy (sf) mutant of the mouse is recognized by the scaliness of the skin from which the name is derived and results in death of affected males at about 3-4 weeks of age. Consideration of known man-mouse homologies of the X chromosome prompted hematological studies, which have shown that the blood is highly abnormal. The platelet and erythrocyte counts are both reduced and become progressively lower relative to normal as the disease progresses. There is gastrointestinal bleeding, and most animals appear to die of severe anemia. By contrast, the leukocyte count is consistently raised. Some animals showed signs of infection but it is not yet clear whether there is immunodeficiency. Other features include the scaly skin and apparently reduced lateral growth of the skin, conjunctivitis, and diarrhea in some animals. The mutant resembles Wiskott-Aldrich syndrome in man, which is characterized by thrombocytopenia, eczema, diarrhea, and immunodeficiency. The loci of the human and mouse genes lie in homologous segments of the X chromosome, although apparently in somewhat different positions relative to other gene loci. Scurfy differs from Wiskott-Aldrich syndrome in that scurfy males are consistently hypogonadal.

Assay of apolipoproteins A-1 and B by immunoturbidimetry: detection of individuals at risk for atherosclerotic artery disease

Recent evidence has suggested that the levels of Apolipoprotein A-1 and B in plasma are better indicators of the risk of atherosclerotic artery disease than plasma lipids. This study describes the measurement of plasma Apolipoprotein A-1 and B by immunoturbidimetry in patients with atherosclerotic artery disease and in normal controls. Apoprotein B and the ratio of Apoprotein A-1/Apoprotein B were found to be the best discriminators between the two groups.

Effects of aerobic conditioning in lupus fatigue: a pilot study

Fatigue, a complex symptom, significantly affects the quality of life in many patients with systemic lupus erythematosus (SLE). To understand this phenomenon, 23 patients with SLE and fatigue were studied. Standardized tests of depression (NIMH), fatigue, exercise tolerance (ETT) on a bicycle ergometer, and SLE activity were obtained. At baseline, SLE patients had significantly lower maximum oxygen consumption (VO2 max) than normals (p less than 0.005). Adjusted for age and sex, SLE patients perform at 54% of their expected maximum VO2, which is similar to published data from patients with rheumatoid arthritis. Depression by NIMH was not correlated with VO2 max or length of time on ETT. Fatigue measured by Profile of Mood States (POMS) was correlated with ETT time (r = 0.476, p less than 0.025) and with VO2 max (r = -0.402, p less than 0.07). After an 8-week aerobic conditioning programme the experimental group increased their aerobic capacity by 19% in contrast to 8% in controls. This change correlated with decreased fatigue as measured by visual analogue scales. Exercise did not exacerbate disease, and only two of 16 experimental subjects experienced transient joint symptoms during exercise.

Refined physical and genetic mapping of the NF1 region on chromosome 17

A total of 15 polymorphic markers were used to construct a genetic map that encompasses the NF1 locus on chromosome 17. The markers were a subset of a large collection of chromosome 17-specific probes and were selected for marker typing in NF1 families after physical localization to the pericentric region of the chromosome. Multilocus data for a total of 17 informative NF1 families and 39 other families were included in genetic analyses. No recombination was observed between NF1 and four markers, one or more of which was informative in 86% of parents. More-refined physical mapping studies demonstrated that all four of the markers are proximal to the chromosome 17 translocation breakpoints from two NF1 patients bearing balanced translocations. The region flanking the disease locus spans a distance of 1 centimorgan (cM) in males and 9 cM in females. Close flanking markers were informative in 76% of meioses. Sex differences in recombination rates in the pericentric region were highly significant statistically.

Delirium after elective orthopedic surgery: risk factors and natural history

Forty-six orthopedic patients were studied to determine the incidence, natural history, and risk factors associated with post-operative delirium. Pre-operatively, patients were given a neuropsychological screening evaluation, the Mood Adjective Checklist (MACL), the Zung Depression Scale, the Anxiety Inventory Scale, and the Health Assessment Questionnaire (HAQ). A psychiatrist interviewed each patient on post-op day four for evidence of delirium as defined by DSM III criteria. Of the patients studied, thirteen (26%) were possibly or definitely delirious following surgery. Treatment with propranolol, scopolamine, or flurazepam (Dalmane) conferred a relative risk for delirium of 11.7 (p = 0.0028). Delirium was associated with increased post-operative complications (p = 0.01), poorer post-operative mood (p = 0.06), and an increase of about 1.5 days in length of stay (not significant). Delirious patients were significantly less likely than matched controls to improve in function at six months compared with a pre-operative baseline HAQ (t = 6.43, p less than 0.001).

Effects of semantic priming on visual encoding of pictures

We investigated the effects of semantic priming on initial encoding of briefly presented pictures of objects and scenes. Pictures in four experiments were presented for varying durations and were followed immediately by a mask. In Experiments 1 and 2, pictures of simple objects were either preceded or not preceded by the object's category name (e.g., dog). In Experiment 1 we measured immediate object identification; in Experiment 2 we measured delayed old/new recognition in which targets and distractors were from the same categories. In Experiment 3 naturalistic scenes were either preceded or not preceded by the scene's category name (e.g., supermarket). We measured delayed recognition in which targets and distractors were described by the same category names. In Experiments 1-3, performance was better for primed than for unprimed pictures. Experiment 4 was similar to Experiment 2 in that we measured delayed recognition for simple objects. As in Experiments 1-3, a prime that preceded the object improved subsequent memory performance for the object. However, a prime that followed the object did not affect subsequent performance. Together, these results imply that priming leads to more efficient information acquisition. We offer a picture-processing model that accounts for these results. The model's central assumption is that knowledge of a picture's category (gist) increases the rate at which visual information is acquired from the picture.

The order of loci in the pericentric region of chromosome 17, based on evidence from physical and genetic breakpoints

Previous genetic analyses of chromosome 17 markers and NF1 (Fain et al. 1987) were extended in an attempt to order marker loci that map physically to 17cen----17q12. Three additional markers (HHH202, CRI-L581, and CRI-L946) were included in the analyses. Recombinants within the cluster of seven unordered marker loci were identified by pairwise analyses for each family and by examining the within-sibship segregation patterns for different markers. Changes in the segregation pattern for different loci define genetic breakpoints. Given that interference is complete in the region, markers with the same segregation pattern lie on one side of the breakpoint, while markers with different segregation patterns lie on opposite sides of the breakpoint. If the order of boundary markers is known, markers on each side of a breakpoint can be oriented in relation to the centromere. The order cen-(HHH202/NF1)-(EW207)-(EW203/CRI-L581)- (CRI-L946)-(HOX-2/NGFR)-qter was inferred by combining information from physical breakpoints in a panel of mouse/human hybrids and information from genetic breakpoints found in 16 NF1 families.

Restriction fragment polymorphisms of the HLA-DR, HLA-DQ, and insulin gene regions in IDDM: the GAW5 data

The primary aim of the insulin-dependent diabetes mellitus (IDDM) component of Genetic Analysis Workshop 5 (GAW5) was to collect and analyze new data on DNA polymorphisms closely linked to the HLA-D region and the insulin gene. The probes and restriction enzymes described here were used by all ten participating labs, and the data from Southern blotting were interpreted and reported according to conventions developed for the Workshop. These DNA data on members of 94 families with two or more IDDM sibs constitute the largest such sample available. The data were used in most of the analyses presented at the Workshop meeting, and are available on request.

Massive schwannoma of the nose and paranasal sinuses

Schwannomas, uncommon tumors of the nose and paranasal sinuses, are discovered late in their clinical course because of their obscure anatomic location. In this report, we have described the clinical findings in a massive nasal schwannoma (neurilemoma) that obstructed both nares, the left maxillary sinus, and the ethmoid sinuses, and protruded from the oropharynx and nose. The preoperative work-up included both computerized tomographic and magnetic resonance imaging studies.

A mapped set of DNA markers for human chromosome 17

We have developed and mapped by genetic linkage a primary set of markers for chromosome 17. The map consists of 21 loci derived from 27 probe/enzyme systems, including eight highly informative markers at loci containing a variable number of tandemly repeated DNA sequences (VNTRs). The map is continuous from the telomeric region of the short arm to the telomeric region of the long arm, covering estimated genetic distances of 218 cM in males and 279 cM in females. The average heterozygosity among all 21 loci in the population sample analyzed is 58%; 77% heterozygosity was observed among the eight VNTR markers that were highly informative. This map will make it possible to detect by linkage the location of genetic defects associated with chromosome 17 and will also provide anchor points for a high-resolution map of this chromosome.

Quantitative analyses of the binding of soluble complement-fixing antibody/dsDNA immune complexes to CR1 on human red blood cells

We have used direct binding isotherm analyses to measure the association constant (Ka) and number of binding sites for the binding of prepared complement-fixing antibody (Ab)/dsDNA immune complexes (IC) to human red blood cells (RBC). In order to generalize this study we have examined the binding reaction for a number of different anti-dsDNA Ab (from systemic lupus erythematosus plasmas), complement sources, RBC donors, and dsDNA sizes. The affinity of the IC for the RBC is quite high, and the Ka values fall within a narrow range (5 to 14 X 10(10) liter/mol). Similarly, the limiting stoichiometries for the number of IC bound per RBC were between 40 and 91. The very high affinity and limiting stoichiometries both suggest that the IC bind to the RBC via multiple contacts with clusters of complement receptor type 1 (CR1). Furthermore, we have used three specific monoclonal AB (mAb) to quantitate CR1 on human RBC in the presence and absence of bound IC. One of these Ab, mAb 1B4, is blocked from binding to the RBC if IC are previously bound, and we have used this observation to verify the multivalent nature of the interaction of complement-fixing IC with CR1 on human RBC.

Quantitative analyses of the binding of soluble complement-fixing antibody/dsDNA immune complexes to CR1 on human red blood cells

We have used direct binding isotherm analyses to measure the association constant (Ka) and number of binding sites for the binding of prepared complement-fixing antibody (Ab)/dsDNA immune complexes (IC) to human red blood cells (RBC). In order to generalize this study we have examined the binding reaction for a number of different anti-dsDNA Ab (from systemic lupus erythematosus plasmas), complement sources, RBC donors, and dsDNA sizes. The affinity of the IC for the RBC is quite high, and the Ka values fall within a narrow range (5 to 14 X 10(10) liter/mol). Similarly, the limiting stoichiometries for the number of IC bound per RBC were between 40 and 91. The very high affinity and limiting stoichiometries both suggest that the IC bind to the RBC via multiple contacts with clusters of complement receptor type 1 (CR1). Furthermore, we have used three specific monoclonal AB (mAb) to quantitate CR1 on human RBC in the presence and absence of bound IC. One of these Ab, mAb 1B4, is blocked from binding to the RBC if IC are previously bound, and we have used this observation to verify the multivalent nature of the interaction of complement-fixing IC with CR1 on human RBC.

Genetic analysis of NF1: identification of close flanking markers on chromosome 17

The gene causing von Recklinghausen neurofibromatosis, or NF1, has been more precisely localized in the pericentromeric region of chromosome 17. Narrowing of the location for the disease became possible through the identification of eight new DNA probe genetic markers in the centromeric region. Markers that closely flank the centromere also closely flank the NF1 gene. Although there was evidence against this localization in one recombinant, a review of the clinical records revealed a borderline diagnosis of NF1. Significant sex differences in recombination were observed in the pericentric region, and odds for different orders were less discriminating when sex differences were considered in multilocus analyses. The location of the NF1 gene with respect to the centromere could not be determined because recombinants between NF1 and the centromere were not detected in the set of families tested.

A genomic search for linkage of neurofibromatosis to RFLPs

Our initial attempt to map NF was directed towards chromosomes 4 and 19, both of which had provided positive evidence for linkage in previous reports. This analysis showed no evidence in support of either hypothesis. Our second attempt at mapping NF was a general search of the genome, analysing a set of markers selected according to their degree of polymorphism, chromosomal location, ease of use, and availability. Data for linkage analysis were obtained from 17 multiplex families which are segregating a gene for NF. Linkage analyses were performed using PAP. Of note is the lod score of +1.17 at a recombination fraction of 0.1 between NF and the centromere of chromosome 17.

Gene for von Recklinghausen neurofibromatosis is in the pericentromeric region of chromosome 17

Linkage analysis of 15 Utah kindreds demonstrated that a gene responsible for von Recklinghausen neurofibromatosis (NF) is located near the centromere on chromosome 17. The families also gave no evidence for heterogeneity, indicating that a significant proportion of NF cases are due to mutations at a single locus. Further genetic analysis can now refine this localization and may lead to the eventual identification and cloning of the defective gene responsible for this disorder.

Further linkage data on Norrie disease

We obtained a LOD score of +1.61 using DNA marker L1.28 in 5 generations of a family with Norrie disease, raising the total LOD score to +5.42. There have been no recombinations between the 2 loci in any family to date, making the marker useful for genetic counseling.

Possible importance of PLD repair in the modulation of BrdUrd and IdUrd-mediated radiosensitization in plateau-phase C3H10T1/2 mouse embryo cells

C3H10T1/2 mouse embryo cells exhibiting strong contact inhibition of growth at confluency were grown in the presence of 5-bromodeoxyuridine (BrdUrd) or 5-iododeoxyuridine (IdUrd) (0-1.2 microM) with daily refeeding and exposed to gamma-rays (6 Gy) either in the logarithmic or the plateau phase of growth. Sensitization to radiation was observed in both growth states with increasing concentration of BrdUrd or IdUrd but the degree of sensitization achieved was lower for plateau-phase cells. Because the degree of [H3]BrdUrd incorporation was found to be similar in exponentially growing and plateau-phase cells, it is hypothesized that the radiosensitization caused by pyrimidine analogues may be affected by the physiological state of the cells at the time of irradiation. Delayed plating of plateau-phase cells (6 h) caused an increase in survival, indicating repair of potentially lethal damage (PLD). A greater increase in cell survival was observed in cells that had been grown in the presence of BrdUrd and IdUrd and it was found to increase with increasing concentrations. This analogue-concentration dependent PLD repair activity resulted in an almost complete loss of the radiosensitizing effect in delayed plated plateau-phase cells up to a concentration of about 0.6 microM of BrdUrd and IdUrd. Both compounds, but especially BrdUrd, caused a relaxation in the mechanism of contact inhibition and led to higher cell densities in the plateau phase. The results suggest that repair and/or expression of PLD might be involved in the mechanism underlying BrdUrd and IdUrd-mediated radiosensitization and point out the potential importance of PLD repair in the modulation of the radiosensitizing effect of these compounds in their clinical application.

Life-style and organizational health insurance costs

Most health professionals accept life-style as being causally related to morbidity and mortality, but many managers question this relationship, particularly in relation to corporate health care costs. This research compared responses from a lifestyle questionnaire (HealthScore), age, and organizational size, with Blue Cross/Blue Shield rates for eight work sites in Ohio. HealthScore was demonstrated to be the best predictor of health insurance rates. This relationship held for a secondary analysis involving Blue Shield rates adjusted for company size and coverage.

Evidence for differences among the sectors of potentially lethal damage expressed by hypertonic treatment in plateau-phase V79 cells after exposure to neutrons or gamma rays: the importance of distinction between alpha and beta-PLD forms

Expotentially growing and plateau-phase V79 cells were exposed to various doses of neutrons and plated either immediately or after treatment in hypertonic medium (250-500 mM NaCl) to express radiation-induced potentially lethal damage (PLD). Postirradiation treatment of exponentially growing cells in hypertonic medium (500 mM) resulted in a decrease in both Dq and D0, whereas postirradiation treatment of plateau-phase cells in hypertonic medium (in the range between 200 to 1,500 mM) resulted mainly in a reduction of Dq. This difference in response between exponentially growing and plateau-phase cells may reflect differences in the chromatin structure in cells at various stages of the cell cycle, affecting fixation of radiation-induced damage. Exposure of plateau-phase cells to gamma rays, on the other hand, resulted in a treatment time and salt concentration-dependent decrease in Dq along with a decrease in D0. Repair of neutron-induced, hypertonic treatment-sensitive PLD, measured by delaying treatment for various periods after irradiation, was found to proceed with a t1/2 of about 1 h. This is similar to the repair kinetics obtained by delaying treatment of plateau-phase cells with 150 microM beta-D-arabinofuranosyladenine (araA) after exposure to gamma rays or neutrons and contrasts the repair kinetics observed after exposure of cells to gamma rays. In this case, hypertonic treatment was found to affect a form of PLD repaired with a t1/2 of 10-15 min (beta-PLD) and araA, a different form of PLD, repaired with a t1/2 of about 1 h (alpha-PLD). Based on these results it is hypothesized that the sector of lesions affected by hypertonic treatment and araA coincides after exposure to neutrons (effect on alpha-PLD) but only partly overlaps after exposure to gamma rays (due to the effect on beta-PLD of hypertonic treatment). The results presented, together with previously published observations, suggest a differential induction and/or fixation by hypertonic medium of the alpha- and beta-PLD forms as the LET of the radiation increases. Furthermore, they indicate that direct comparison of the effects of a postirradiation treatment, as well as of the repair kinetics obtained by its delayed application after exposure to radiations of various LET, should be made with caution.

The kinetics of clearance of human antibody/dsDNA immune complexes from rabbit circulation. Effects of dsDNA size, rheumatoid factor, and reduction and alkylation of the antibodies

We have conducted in vivo investigations of the rate of clearance of prepared antibody/dsDNA immune complexes from the circulation of rabbits and have correlated the results with some in vitro immunologic properties of the complexes. Those complexes that fix complement most efficiently in vitro (as manifested by their complement-mediated binding to human red blood cells or rabbit platelets) are cleared most rapidly. Factors that decrease this binding such as reduction and alkylation of the antibodies or the use of dsDNA of a lower m.w. also tend to prolong the circulation times for the complexes. This study provides additional evidence in support of a complement-mediated platelet immune complex clearance mechanism in non-primates that parallels the erythrocyte immune complex clearance mechanism in primates first described by He bert. Finally, the implications of our findings with respect to the importance of dsDNA size in the pathogenesis of systemic lupus erythematosus are discussed.

The kinetics of clearance of human antibody/dsDNA immune complexes from rabbit circulation. Effects of dsDNA size, rheumatoid factor, and reduction and alkylation of the antibodies

We have conducted in vivo investigations of the rate of clearance of prepared antibody/dsDNA immune complexes from the circulation of rabbits and have correlated the results with some in vitro immunologic properties of the complexes. Those complexes that fix complement most efficiently in vitro (as manifested by their complement-mediated binding to human red blood cells or rabbit platelets) are cleared most rapidly. Factors that decrease this binding such as reduction and alkylation of the antibodies or the use of dsDNA of a lower m.w. also tend to prolong the circulation times for the complexes. This study provides additional evidence in support of a complement-mediated platelet immune complex clearance mechanism in non-primates that parallels the erythrocyte immune complex clearance mechanism in primates first described by He bert. Finally, the implications of our findings with respect to the importance of dsDNA size in the pathogenesis of systemic lupus erythematosus are discussed.