Evaluation of the Spot-CAMP test for the rapid presumptive identification of group B streptococci

A rapid Spot-CAMP test was evaluated for its ability to accurately identify colonies of Streptococcus agalactiae (Lancefield Group B) growing on primary sheep blood agar plates. The test uses a beta-lysin-containing filtrate, which is prepared from a broth culture of Staphylococcus aureus. A drop of beta-lysin filtrate is applied adjacent to a suspected group B Streptococcus (GBS) colony and the plate is incubated and then examined for a zone of synergistic hemolysis. The Spot-CAMP test demonstrated 100% correlation with both a Standard CAMP procedure and Lancefield serogrouping. The rapid Spot-CAMP test was easy to perform and inexpensive, and could presumptively identify within 30 minutes colonies of GBS growing on primary isolation plates.     

Rescue of a thymotropic, leukemogenic C-type virus from cultured, nonproducer-lymphoma cells of strain C57BL/Ka mice.

A permanent cell line, BL/RL₁₂-NP, derived from a radiation-induced C57BL/Ka mouse lymphoid tumor, has remained devoid of MuLV expression, except for the rare, sporadic initiation of virus production in some cultures. It can, however, be stably infected by the radiation leukemia virus (RadLV), and the progeny virus population retains the biological and serological properties of the parental RadLV. The cells can also be infected by a B-ecotropic, nonthymotropic, nonleukemogenic C57BL/Ka virus isolate, BL/Ka (B). In the latter situation, the emerging virus particles may exhibit thymotropic and leukemogenic (T+L+) attributes similar to those of RadLV, while retaining at least some of the envelope determinants of BL/Ka (B). These observations suggest that, following productive infection by a nonleukemogenic helper virus, oncogenic sequences endogenous to the non-producer lymphoma cells may be packaged in infectious progeny virions. The data are interpreted as providing strong support for the existence, in radiogenic lymphomas, of defective T+L+ sequences, designated RadLV-O. Possible mechanisms whereby RadLV-O is later expressed as an infectious leukemogenic virus are discussed.     

Refined genetic mapping of autosomal recessive chronic distal spinal muscular atrophy to chromosome 11q13.3 and evidence of linkage disequilibrium in European families

Chronic distal spinal muscular atrophy (Chronic DSMA, MIM (*)607088) is a rare autosomal recessive disorder characterized by a progressive motor weakness and muscular atrophy, predominating in the distal parts of the limbs. A form of Chronic DSMA gene has been previously mapped to chromosome 11q13 in the 10.3 cM interval defined by loci D11S1889 and D11S1321. By linkage analysis in 12 European Chronic DSMA families, we showed that a disease gene maps to chromosome 11q13.3 (Z(max)=6.66 at theta=0.00 at the DSM4 locus) and suggested that this condition is genetically homogeneous. Recombination events allowed us to reduce the genetic interval to a 2.6 cM region, telomeric to the IGHMBP2 gene, excluding this gene as the disease causing gene in Chronic DSMA. Moreover, partial linkage disequilibrium was found between three rare alleles at loci D11S1369, DSM4 and D11S4184 and the mutant chromosome in European patients. Analysis of the markers at these loci strongly suggests that most Chronic DSMA chromosomes are derived from a single ancestor. Refinement of the Chronic DSMA locus will hopefully allow to test candidate genes and lead to identification of the disease-causing mutations.     

Hemolytic uremic syndrome with hypocomplementemia, serum C3NeF, and glomerular deposits of C3

A 4-year-old boy had hemolytic uremic syndrome (HUS) associated with depression of serum C3 level, a B-hemolytic streptococcal throat infection, and an elevated level of antistreptolysin O titer. In addition to the characteristic histologic changes associated with this syndrome, substantial infiltration of polymorphonuclear leukocytes and nodular deposits of C3 globulin were seen in the glomeruli of the first biopsy specimen. Two months after clinical remission, he had a recurrence of hemolytic anemia, thrombocytopenia, and acute renal failure. The serum C3 concentration had decreased again, and serum C3NeF was detected in the serum. The typical changes associated with HUS were still present on electron microscopy. Bilateral nephrectomy and renal transplantation were done because of the development of uncontrollable severe hypertension and increasing azotemia. This patient had three manifestations of HUS, but because of several differences, such as hypocomplementemia, serum C3NeF, a recurrence, and persistent glomerular deposits of C3 globulin, he appears to have had a different form of the syndrome.     

Quantitative assays of pharmacologic aerosols used in studying asthma

To more nearly accurately quantitate the dose of pharmacologic agents delivered to human and animal airways via aerosols, we have developed a monodisperse aerosol containing either methacholine or histamine that permits a light scattering device (tyndallometry) to measure accurately the quantity of inspired and expired particles. These aerosols (described in previous studies) are simultaneously tagged with a radioactive label (technetium 99m) to permit the use of external gamma camera imaging. Present work focuses on the development of assay techniques to measure the quantity of methacholine delivered in these aerosols. The lack of specific radioimmune or radioenzyme assays coupled with the cross-reaction of organic contaminants with conventional chemical reagents for measuring methacholine required the development of separative techniques to isolate the methacholine from the organic aerosol contaminants. With aqueous extraction and column separation we have been able to completely isolate the methacholine from these contaminants. This allows the application of standard spectrophotometric assays for methacholine to quantitate the methacholine in the resulting solution. These separative techniques will permit the use of these aerosols in quantitative studies of airway reactivity.     

Evaluating plasma holds in the presence of multiple infections

To protect plasma supplies, donors are screened for infectiousdiseases. As an added measure of protection, donations are identifiedand stored for a period of time to allow future discard in theevent that an identified donor subsequently tests positive forsome screened disease. Previous models for evaluating such plasmaholds have only addressed the case of a single infectious disease.This paper extends the analysis to the case of multiple infections.Given knowledge of the marginal incidence rates for those infectionschecked, upper and lower bounds for important quantities suchas the probability of interdicting an infectious but undetecteddonation, the expected number of infections interdicted perdonation, and the net economic benefits of the holding policyare developed. Several examples are developed, illustratinghow the models can be used to evaluate the consequences of aplasma hold.     

Linkage analysis of anorexia and bulimia nervosa cohorts using selected behavioral phenotypes as quantitative traits or covariates.

To increase the likelihood of finding genetic variation conferring liability to eating disorders, we measured over 100 attributes thought to be related to liability to eating disorders on affected individuals from multiplex families and two cohorts: one recruited through a proband with anorexia nervosa (AN; AN cohort); the other recruited through a proband with bulimia nervosa (BN; BN cohort). By a multilayer decision process based on expert evaluation and statistical analysis, six traits were selected for linkage analysis (1): obsessionality (OBS), age at menarche (MENAR), and anxiety (ANX) for quantitative trait locus (QTL) linkage analysis; and lifetime minimum body mass index (BMI), concern over mistakes (CM), and food-related obsessions (OBF) for covariate-based linkage analysis. The BN cohort produced the largest linkage signals: for QTL linkage analysis, four suggestive signals: (for MENAR, at 10p13; for ANX, at 1q31.1, 4q35.2, and 8q13.1); for covariate-based linkage analyses, both significant and suggestive linkages (for BMI, one significant [4q21.1] and three suggestive [3p23, 10p13, 5p15.3]; for CM, two significant [16p13.3, 14q21.1] and three suggestive [4p15.33, 8q11.23, 10p11.21]; and for OBF, one significant [14q21.1] and five suggestive [4p16.1, 10p13.1, 8q11.23, 16p13.3, 18p11.31]). Results from the AN cohort were far less compelling: for QTL linkage analysis, two suggestive signals (for OBS at 6q21 and for ANX at 9p21.3); for covariate-based linkage analysis, five suggestive signals (for BMI at 4q13.1, for CM at 11p11.2 and 17q25.1, and for OBF at 17q25.1 and 15q26.2). Overlap between the two cohorts was minimal for substantial linkage signals.     

Electron microscopic studies of the DNA of defective and standard pseudorabies virions.

DNA from standard and defective virus particles was analyzed by electron microscopy. Upon partial denaturation the DNA molecules from standard pseudorabies virus showed distinct denaturation patterns. The molecules are asymmetrical with respect to adenine-thymidine (A-T) content, having several A-T-rich regions on the “left” side and only one on the “right” side of the molecule. The fact that a distinct denaturation map was obtained indicates that the molecules are not circularly permuted. On the extreme left of the molecule a segment of approximately 0.5 μm invariably contained denatured regions, whereas this was not evident on the right side of the molecule. Thus, if the molecule is terminally redundant, the redundant region covers a relatively small part of the viral genome. The contour length of the DNA molecules present in defective, interfering particles was found to be similar to that of standard DNA. Under partial denaturation conditions a distinct segment of DNA (1.1 μm in length) was found to be tandemly repeated in defective DNA. The number of repeats in different molecules varied. In some of the DNA molecules as many as 17 consecutive repeats were found, whereas in others no repeats were seen. Repeated segments were not detected in standard DNA.     

Freeze Dried Platelets for HLA Alloantibodies Absorption

Antibodies to HLA–A and B are specifically absorbed onto platelets. A method of absorption of these antibodies using freeze dried platelets is described. This method allows long-term storage and standardized absorption procedures. Anti-DR antibodies and cold lymphocytotoxins are recovered in the supernatant.