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Biomedical subjects

C Hughes

Publications and source records attributed to C Hughes.

At least 307 records · Page 17Linked to original sources
PubMed1977

Rapid screening for plasmid DNA.

A procedure is described for demonstrating plasmid DNA and its molecular weight, based on rate zonal centrifugation of unlabelled DNA in neutral sucrose gradients containing a low concentration of ethidium bromide. Each DNA species is then visualized as a discrete fluorescent band when the centrifuge tube is illuminated with ultra-violet light. Plasmids exist as closed circular and as relaxed circular molecules, which sediment separately, but during preparation of lysates, closed circular molecules are nicked so that each plasmid forms only a single band of relaxed circles within the gradient.

Centrifugation, Density Gradient↗
PubMed1976

Nalidixic acid as a selective agent for the isolation of enterobacteria from river water.

Enterobacteria are more resistant to nalidixic acid than the majority of other Gram-negative organisms isolated from river water, so allowing their selection on MacConkey agar containing nalidixic aicd. Selection is further improved by anaerobic incubation which, with nalidixic acid, virtually eliminates oxidase-postivie strains such as Pseudomonas or Aeromonas.

Ampicillin↗
PubMed1973

Isolation and characterization of a rough microsomal fraction from rat kidney that is enriched in lysosomal enzymes.

1. A special population of rough microsomal material (microsomes) rich in lysosomal acid hydrolases was separated by isopycnic centrifugation as a discrete fraction (RM(2)) from the bulk of rough microsomal material in rat kidney because of its greater density. 2. The specific activities of five acid hydrolases in the RM(2) fraction were approximately one-half those of a purified lysosomal (L) fraction and 10- to 30-fold greater than those of an ordinary rough microsomal (RM(1)) fraction. 3. These special rough microsomes have a distinctive ultrastructure and electron-cytochemical properties. Their cisternal content resembles the matrix of lysosomes in that it is electron-dense, osmiophilic and plumbophilic and gives a positive reaction for acid phosphatase activity. 4. Polyacrylamide-gel electrophoresis of soluble proteins from the L fraction resolved nine anionic glycoproteins, most of which exhibit acid hydrolase activities (Goldstone & Koenig, 1970, 1973; Goldstone et al., 1971a). The most anionic glycoprotein is the acidic lipoglycoprotein of the lysosomal matrix (Goldstone et al., 1970). 5. Polyacrylamide-gel electrophoresis of soluble proteins from the RM(2) fraction resolved two cationic glycoproteins with acid hydrolase activities (Goldstone & Koenig, 1973) and an anionic glycoprotein with the same electrophoretic mobility as the lysosomal lipoglycoprotein, but without its lipid constituents or capacity to bind the basic fluorochrome Acridine Orange. These constituents are considered to be the precursors of the lysosomal glycoproteins.

Acid Phosphatase↗
PubMed1969

Hormone storage granules in the beef anterior pituitary. I. Isolation, ultrastructure, and some biochemical properties.

A method is described for isolation of relatively large quantities of large and small hormone storage granules from the beef adenohypophysis. The hormone storage granules are highly purified, as indicated by ultrastructural and biochemical criteria. The average size of large granules is 400 mmicro and of small granules is 220 mmicro. The large granules contain growth hormone and prolactin; the small granules contain high concentrations of follicle-stimulating, luteinizing, and thyroid-stimulating hormones. An alkaline protease with a pH optimum of 8.3 is associated with the small granule fraction.

Animals↗
PubMedDate not supplied

The role of macrophages in primary and secondary infection of mice with Salmonella typhimurium.

Elimination of macrophages with high-molecular dextran sulphate (DS) markedly impairs resistance of mice to primary infection with smooth, virulent strains of Salmonella typhimurium, whereas stimulation of this system by killed Bordetella pertussis organisms increases resistance. In infection with rough, avirulent strains of S. typhimurium the elimination of macrophages was not followed by an essential loss of resistance, and it appears that other non-specific defence mechanisms, for example the complement system, may have compensated for the lack of macrophages. Macrophages, therefore, play an important role in defence during primary infection with virulent strains. In immunity to challenge infection with S. typhimurium, macrophages play an even more significant role. Treatment with DS completely removes immunity, and both humoral and cell-mediated immune mechanisms seem to require the participation of macrophages.

Animals↗
PubMedDate not supplied

Ethnic differences in knowledge and attitudes about BRCA1 testing in women at increased risk.

Informed consent for BRCA1 mutation testing will require adequate knowledge of patterns of inheritance of cancer and the benefits, limitations, and risks of DNA testing. This study examined knowledge about the inheritance of breast cancer and attitudes about genetic testing for breast-ovarian cancer susceptibility in women at increased risk. Knowledge and attitudes were measured in 407 African American and Caucasian women aged 18-75 who had at least one first-degree relative (FDR) with breast and/or ovarian cancer. The average knowledge score was 6.0 out of a total of 11 (S.D. = 2.15). Compared to Caucasian women, African American women had lower levels of knowledge and had more positive attitudes about the benefits of genetic testing. There were no significant ethnic differences in attitudes about the limitations and risks of testing, however, income was negatively associated with this outcome. Ethnic differences in knowledge and attitudes about genetic testing for breast-ovarian cancer risk may be attributable to differences in exposure to genetic information and referral by health care providers.

Adolescent↗
PubMedDate not supplied

Salmonella typhimurium strains carrying haemolysin plasmids and cloned haemolysin genes from Escherichia coli.

Like all other Salmonella typhimurium strains examined, the smooth variants SF1397 (LT2) and 1366 and also their semi-rough and rough derivatives are non-haemolytic. Nevertheless, two haemolysin (Hly) plasmids of E. coli belonging to the inc groups incFIII,IV (pSU316) and incI2 (pHly152) were able to be introduced into these strains by conjugation and stably maintained. A considerable percentage of the Hly+ transconjugants obtained had lost parts of their O-side chains, a result of selection for the better recipient capability of "semi-rough" variants rather than the direct influence of the Hly+ plasmids themselves. In contrast to the incFIII,IV plasmid pSU316, which exhibited higher conjugation rates with rough recipients, the incI2 plasmid pHly152 was accepted best by smooth strains. Transformation with cloned E. coli haemolysin (hly) determinant was inefficient (less than 10(-6)) for smooth strains, but 10(2) - 10(3) times higher for rough recipients, and was increased by the use of Salmonella-modified DNA. The transformants and transconjugants were relatively stable and showed the same haemolytic activity as the E. coli donor strains. The virulence of the Hly+ smooth, semi-rough and rough S. typhimurium strains was tested in two mouse models, and neither the mortality rate nor the ability to multiply within the mouse spleen was influenced by the hly determinants.

Animals↗
PubMedDate not supplied

Teaching students to self-regulate their behavior: the differential effects of student-vs. teacher-delivered reinforcement.

The effects of selected student-directed learning strategies on the classroom behavior of six students with varying disabilities in general education were examined using a multiple baseline design across groups. Target behaviors included academic, study, and social skills. Results indicated increases in student target performance for all participants, however, differential effects were observed across groups and reinforcement conditions (student-vs. teacher-delivered). Additionally, anecdotal reports obtained from the cooperating teacher and students supported the study's findings. The implications of these findings are discussed.

Adolescent↗
PubMedDate not supplied

Effect of delayed blood processing on the yield of factor VIII in cryoprecipitate and factor VIII concentrate.

Current standards for the preparation of factor VIII (FVIII) concentrates from human plasma recommend separation of plasma from red cells (RBCs) within 6 hours of blood donation, thereby reducing the volume of plasma from donated whole blood available for processing to FVIII concentrate. The decay of FVIII clotting activity (FVIII:C) in whole blood and plasma stored at 22 and 4 degrees C and the recovery of FVIII:C in cryoprecipitate and FVIII concentrate prepared from plasma separated from whole blood stored overnight at 4 degrees C were investigated. In whole blood stored at 22 degrees C and plasma stored at either 4 or 22 degrees C, 90 percent of the original FVIII:C was present at 6 hours, 80 percent at 12 hours, and 65 to 70 percent at 18 hours. At these times lower levels of FVIII:C were recovered from whole blood stored at 4 degrees C, that is, 84, 68, and 56 percent, respectively. In cryoprecipitates prepared from plasma separated from RBCs after 18 hours' storage at 4 degrees C (18-hour plasma), 43 percent of FVIII:C activity was recovered, as compared with 61 percent recovered from standard plasma separated within 6 hours of donation (6-hour plasma), p less than 0.05. With large-scale preparation of FVIII concentrates, however, the yield of FVIII:C was similar whether 18- or 6-hour plasma was used. Thus FVIII concentrates--but not cryoprecipitates--can be prepared from plasma separated from whole blood stored at 4 degrees C for up to 18 hours without undue loss of potency.

Antigens↗
PubMedDate not supplied

The experience of being a grandmother who is the primary caregiver for her HIV-positive grandchild.

BACKGROUND: The number of grandparents assuming care for their grandchildren is increasing, and this affects grandparents both positively and negatively. The current study builds on an earlier study of the effects of social support, stress, and level of illness on caregiving of children with acquired immune deficiency syndrome (AIDS) that identified both positive and negative effects of caregiving. OBJECTIVES: To identify the lived experience of African American and Latino grandmothers as the primary caregivers for their grandchildren who are human immunodeficiency virus (HIV)-infected or have AIDS and to identify the similarities and differences between the two groups. METHODS: Using Van Manen's method for hermeneutical phenomenological research, the lived experiences of 10 African American and Latino grandmothers who were the primary caregivers for their HIV-positive grandchildren were investigated. Additionally, the similarities and differences between the two groups were studied. RESULTS: Four themes identified were (a) upholding the primacy of the family, (b) living in the child-centered present, (c) being strong as mature women, and (d) living within a constricting environment. Twelve subthemes expanded and clarified the meaning of these themes. CONCLUSIONS: Although there were differences related to family structure and cultural backgrounds, the grandmothers were more alike than different.

Adaptation, Psychological↗
PubMedDate not supplied

"I got some swords and you're dead!": violent fantasy, antisocial behavior, friendship, and moral sensibility in young children.

Relations between an early interest in violent fantasy and children's social understanding, antisocial and emotional behavior, and interactions with friends were investigated in 40 "hard-to-manage" preschoolers and 40 control children matched for gender, age, and school and ethnic background. Children were filmed alone in a room with a friend, and tested on a battery of cognitive tests, including false-belief, executive function, and emotion understanding tasks. Teachers reported on their friendship quality. At age 6 years, the children's understanding of the emotional consequences of antisocial and prosocial actions was studied. The hard-to-manage group showed higher rates of violent fantasy; across both groups combined, violent fantasy was related to poor executive control and language ability, frequent antisocial behavior, displays of anger and refusal to help a friend, poor communication and coordination of play, more conflict with a friend, and less empathic moral sensibility 2 years later. The usefulness of a focus on the content of children's pretend play-in particular, violent fantasy-as a window on children's preoccupations is considered.

Age Factors↗
PubMedDate not supplied

The effect of five proofreading conditions on the spelling performance of college students with learning disabilities.

This study investigated the effect of five proofreading conditions on the spelling performance of 12 college students with learning disabilities on a composition activity. The proofreading conditions investigated were handwriting with no additional assistance, handwriting with a conventional print dictionary, handwriting with a handheld spelling checker, word processing with no additional assistance, and word processing with an integrated spelling checker. A repeated measures ANOVA was used to analyze the results, with proofreading condition used as a within-participants factor. Except for handwriting alone, all of the techniques resulted in significant reductions in the number of spelling errors in the students' written work; however, none of the techniques enabled the students to produce compositions with a mean level of spelling accuracy comparable to that of their nondisabled peers.

Achievement↗