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Biomedical subjects

C Heller

Publications and source records attributed to C Heller.

13 recordsLinked to original sources
PubMed1992

Field inversion gel electrophoresis in denaturing polyacrylamide gels.

The velocities of single stranded DNA molecules in denaturing polyacrylamide gels during symmetric and asymmetric field inversion were measured at different pulse times and gel concentrations. Under the conditions chosen in our study, pulse times as short as a few milliseconds lead to a retardation of DNA molecules larger than 400 bases. We found that a field inversion with an electric field in the forward direction of about double the strength of that applied in the backward direction is a good compromise between the degree of retardation, the temperature control requirements and the run time of the gel.

DNA, Single-Stranded↗
PubMed1992

A short-term psychiatric inpatient program for adolescents.

Third-party payers have become increasingly unwilling to fund long-term hospitalizations for adolescents. Inpatient adolescent programs have had to develop strategies to treat this difficult patient population much more rapidly. In late 1989 a short-term adolescent treatment program, known as the STAT program, was developed and implemented at a private psychiatric hospital in Massachusetts. The program aimed for a two- to three-week length of stay, a reduction of 30 to 50 percent. To accomplish this goal, the program shifted from a treatment-based approach to a focus on crisis management, patient evaluation and stabilization, and transition to outpatient services. Many staff concerns were allayed during the program's implementation. Short-term treatment for adolescents can be viable if appropriate exclusion criteria are developed for admissions and an adequate range of outpatient treatment services are available.

Adolescent↗
PubMed1991

Model and computer simulations of the motion of DNA molecules during pulse field gel electrophoresis.

A model is presented for the motion of individual molecules of DNA undergoing pulse field gel electrophoresis (PFGE). The molecule is represented by a chain of charged beads connected by entropic springs, and the gel is represented by a segmented tube surrounding the beads. This model differs from earlier reptation/tube models in that the tube is allowed to leak in certain places and the chain can double over and flow out of the side of the tube in kinks. It is found that these kinks often lead to the formation of U shapes, which are a major source of retardation in PFGE. The results of computer simulations using this model are compared with real DNA experimental results for the following cases: steady field motion as seen in fluorescence microscopy, mobility in steady fields, mobility in transverse field alternation gel electrophoresis (TFAGE), mobility in field inversion gel electrophoresis (FIGE), and linear dichroism (LD) of DNA in agarose gels during PFGE. Good agreement between the simulations and the experimental results is obtained.

Chemical Phenomena↗
PubMed1991

Biotinylation of transducin and G0 from bovine brain.

A method is described for modifying G proteins with biotin. With transducin, better results were obtained with the amino group-specific derivative BXNHS (biotinyl-epsilon-aminocaproic acid N-hydroxysuccinimide ester) as compared to the -SH-group specific reagent MBB (maleimidobutyrylbiocytin). Modification occurred under conditions preserving functional activity: Interaction of the biotinylated transducin with rod outer segment membranes was shown by its light-dependent association and by a GTP gamma S-binding assay. G0 from bovine brain was also biotinylated under conditions preserving its activity. Biotinyl-alpha 0 was shown to bind to a streptavidin Sepharose matrix. Biotinyl-G proteins, therefore, are proposed as tools for extracting proteins (receptors and effector systems), which interact under specific conditions with G proteins.

Animals↗
PubMed1990

Field inversion gel electrophoresis with different pulse time ramps.

The influence of different pulse time ramps on the separation of yeast chromosomes with field inversion gel electrophoresis (FIGE) was investigated by the means of two dimensional gel electrophoresis. The problem of band inversion, which makes it difficult to distinguish DNA molecules of different size, has been solved by using double randomized pulse times. A major disadvantage of the field inversion technique is thereby overcome, making this system comparable to other pulsed field techniques.

Chromosomes, Fungal↗
PubMed1989

A systematic study of field inversion gel electrophoresis.

The mobilities of oligomers of phage lambda DNA and of yeast chromosomes in agarose gels during field inversion gel electrophoresis (FIGE) were measured at different pulse times and electric fields. Also the ratios between forward and backward pulse times and/or field gradients were varied. The problem of 'band inversion' during FIGE, leading to an ambiguity in the mobility of large DNA fragments, was solved by using two dimensional gel electrophoresis with different parameters in the first and second dimension. The results are compared with those obtained with other pulsed electrophoresis systems and with a theoretical model.

Bacteriophage lambda↗
PubMed1989

Fatal accidental enflurane intoxication.

Among reported cases of abuse of volatile anesthetics there is only one of enflurane intoxication. We report another fatal enflurane intoxication. A 21-year-old man found dead seemed to have experimented with enflurane. Three and one-half days after death high amounts of enflurane were detected in blood, brain, and subcutaneous fat. Gas chromatographic quantification revealed the following high enflurane concentrations: blood: 130 mg/l-1, brain: 350 mg/l-1, and subcutaneous fat: 100 mg/l-1. Histologic signs of drug-induced damage were lacking. No suicide intentions became known. It was concluded that the young man died of an accidental intoxication while abusing enflurane.

Adult↗
PubMed1989

DNA sequencing with direct blotting electrophoresis and colorimetric detection.

We describe optimized procedures for colorimetrically-detected DNA sequencing with direct blotting electrophoresis. One-step protocols for Sequenase and Klenow enzyme are given. The clapping technique has been adapted to allow convenient casting of very thin gels with an optimal lower gel (transfer) surface. This gives very sharp band patterns, enabling more than 350 bases from a single loading to be read with confidence. The crucial points for direct blotting electrophoresis are discussed. Background problems resulting from unspecific binding of streptavidin to the nylon membranes have been eliminated by the use of high concentrations of SDS in the incubation buffer; and using a single large glass tube for all incubation and washing steps is a very convenient and effective development protocol. Automation of the colorimetric development process is described.

Base Sequence↗
PubMed1978

Specific cell-induced transformation of Paramecium surface antigens.

Paramecia may induce in other paramecia specific changes in the expression of genes determining surface protein synthesis, probably via cell-to-cell contact. Transformation from one antigenic type to a newly induced one is stimulated by the pretreatment of a cell with 5-fluorouracil. These observations are considered in terms of the regulation of the activity of genes in stable cells and in unstable cells which tend to transform spontaneously.

Animals↗
PubMed1976

Rhmod, a second kindred (Craig).

Three Rhmod siblings were found to have identical Rh: w1, w2, -3, -4, w5 (see article) phenotypes. All had stomatocytic hemolytic anemia. On quantitative hemagglutination studies, as well as on hand tests, all Rh antigens were not equally depressed. Rh17 (Hr0, 'not D') and Rh29 (RH, 'total Rh') were both normal. Rh5 (hr", e) was only slightly depressed. Rh25 (LW) had 50% of the expression expected in normal Rh:-1 cells. Rh1 (Rh0, D), Rh13 (RhA), Rh14 (RhB), Rh15 (RhC), and Rh16 (RhD), were severely depressed. Rh2 (rh', C) was depressed, while Rh7 (rhi, Ce) was absent. Both Rh19 (hrS) and Rh31 (hrB) were depressed. Rh12 (rhG, G) was distinctly depressed, scoring considerably less than rGrG red cells. The unrelated parents, the child of the proposita, and some siblings of each parent showed lessened depression of Rh antigens without displaying the consistent pattern that might be expected from a presumed single suppressor gene. Absence of a consistent pattern may have resulted from differing Rh genotypes, but a frequently observed depression involved Rh14, Rh15, and Rh16 (RhB, RhC, and RhD) without an effect on either Rh1 (RH3 or D) or Rh13 (RhA).

Female↗
PubMed1975

Quantitative Rh typing of r-Gr-G with observations on the nature of G (Rh 12) and anti-G.

Quantitative blood typing data on Mr. R. B. (r-Gr-G), his wife (R1r), a daughter (R1r-G), and a niece (r-Gr) strongly suggest that these Rh phenotypes are directly indicative of actual Rh genotypes. If so, the antigenic products of r-G are weak Rh2(rh' or C), normal Rh5 (hr" or e), an expression of Rh12 (rh-G) equal to that produced by R-1,2,-3 (r' or dCe) and half of what is produced by R1 (R or D) genes in either homozygous or heterozygous expression, very weak expression of Rh19 (hr-S), absence of Rh31 (hr-B), and slightly weakened expression of Rh17 (Hr-o or 'not D'). The LW status of r-Gr-G cells was equivalent to that of other Rh:-1 erythrocytes. Thus r-G resembles mutant r' in which only Rh5 is expressed normally. The weak Rh2 produced by r-G reacted much better with one Rh2 antiserum than with another. Rh21 (C-G) had been used to denote such additional reactivity, but one reagent that acted as anti-Rh2 in manual tests behaved like anti-Rh21 in instrumented tests. Therefore, anti-Rh21 may only indicate a more efficiently agglutinating anti-Rh2. Mr. R. B. showed no evidence of congenital stomatocytic hemolytic anemia characteristic of Rh-null or Rh-mod. Finally, anti-Rh12 eluates, recovered either sequentially from r'r followed by R2r or singly from r-Gr-G, agglutinated chimpanzee red cells more efficiently than did either anti-Rh1 (D) or anti-Rh4 (c), a result consistent with expectation for serological crossreactivity between Rh1 and Rh21.

Adult↗