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Biomedical subjects

C Roberts

Publications and source records attributed to C Roberts.

At least 451 records · Page 25Linked to original sources
PubMed1967

Pathological findings in three cases of fungal endocarditis complicating open-heart surgery.

Three cases of fungal endocarditis are described, each following a homograft valve replacement for aortic stenosis. The causative organism was C. albicans. The characteristic findings included soft, easily detached vegetations consisting of fungal colonies, aneurysms, embolization of large vessels, and lack of response to current therapeutic measures. The source of the infection is obscure.

Adult↗
PubMedDate not supplied

High resolution MR imaging and localization of laser-induced thermal injury in the vascular wall.

With the increasing use of lasers in surgical procedures, there is need for a noninvasive imaging modality to monitor laser-tissue interactions. MRI can be used readily for imaging human anatomy and holds the potential to map laser-induced thermal injury. This study investigates high resolution T1-weighted MR imaging of human aorta samples (in vitro) that have been damaged thermally using an argon ion laser and the corresponding histology. High resolution T1-weighted MR images (voxel size, .156 x .156 x .700 mm) clearly detected residual thermal injury as areas of bright signal intensity. Effective localization of thermal injury was achieved by subtraction of preinjury and postinjury slices with pseudocoloring of positive and negative differences. The results may serve as a basis from which to guide future in vivo studies.

Adult↗
PubMedDate not supplied

Assessing effects of serotonin precursors on newborn behavior.

While traditional studies of newborn diet have focused on the effects of malnutrition on the central nervous system, there is now interest in how qualitative differences in the composition of early newborn feeding might influence behavior. This paper reviews the available techniques for assessing newborn perception and cognition, as well as behavioral organization. The paper then focuses intensively on measures of newborn state behaviour in view of evidence in adult humans, as well as in non-human species, suggesting a relationship between sleep behavior (sleep onset, night waking) and brain serotonin levels. A study designed to examine the relationship between dietary precursors of brain serotonin (within the range of concentrations found in human milk) and newborn state behavior after feeding is described to illustrate the application of these techniques. Healthy, fullterm newborns were fed a modified formula, containing tryptophan or valine, on one day, a routine formula on another day, and observed continuously for 3 h after each feeding for the observation and recording of newborn state. Data from individual infants in the tryptophan and valine groups are presented to illustrate the findings that infants fed tryptophan entered quiet sleep and active sleep sooner than infants fed valine and spent more time in active sleep and less time alert. These results illustrate the value of newborn behavior as a sensitive dependent variable in studies of behavioral effects of diet and suggests that variations in serotonin levels in the newborn brain may modulate the newborn's sleep/wake behaviour.

Brain Chemistry↗
PubMedDate not supplied

Human cutaneous leishmaniasis caused by Leishmania donovani s.l. in Kenya.

Our laboratory is characterizing Leishmania stabilates and isolates from active leishmaniasis cases. Smears and cultures from aspirates made on different dates from a single lesion on the bridge of the nose of an 18 years old Kenyan male from Nyandarua District contained Leishmania. The isolates, NLB-271 and NLB-271-IA, were characterized by cellulose acetate electrophoresis (CAE) using 20 enzyme systems and by Southern analysis using 2 deoxyribonucleic acid (DNA) probes (pDK10 and pDK20) from a Dakar strain of L. major (MHOM/SN/00/DK1) and a third probe, p7-059 from L. infantum strain ITMAP-263. Digestion of the two Leishmania DNAs with endonucleases HindIII and PstI, followed by hybridization with the 3 probes, revealed DNA fragment banding patterns indistinguishable from those of the L. donovani species complex. The CAE isoenzyme profiles of these 2 Kenyan isolates were indistinguishable from those of Kenyan L. donovani strains we designated as zymodeme Z6. Excluding post-kala-azar dermal leishmaniasis, this constitutes the first human case of cutaneous leishmaniasis caused by L. donovani s.l. in Kenya. Previously, cutaneous leishmaniasis cases in Kenya have been due to L. aethiopica, L. major and L. tropica only.

Adolescent↗
PubMedDate not supplied

The effect of lipofuscin on cellular function.

The neurons of the supraoptic nucleus of male C57BL/Icrfat mice at 6 or 28 months of age were examined from normally hydrated, osmotically loaded and osmotically loaded-rehydrated animals. Using quantitative morphological techniques, a reduction in the concentration of lipofuscin in the neurons was observed in osmotically loaded mice at both ages, and these levels were restored to control values during rehydration. In addition, there was a significant difference in the pattern of response of lipofuscin levels between the two age groups during the experiment. The concentration of hormone containing neurosecretory granules in the neurons of the supraoptic nucleus did not differ significantly between the two age groups during the experiment. However, the surface area of rough endoplasmic reticulum per unit volume of the supraoptic nucleus cell did differ significantly between the two age groups over the course of the experiment. It is concluded that increasing concentrations of lipofuscin do not affect the ability of the cell to control the concentration of neurosecretory granules or rough endoplasmic reticulum. The simplistic view that lipofuscin accumulates with age to the detriment of cell function must be revised.

Aging↗
PubMedDate not supplied

Importance of h5-HT1B receptor selectivity for 5-HT terminal autoreceptor activity: an in vivo microdialysis study in the freely-moving guinea-pig.

The importance of h5-HT1B receptor selectivity for 5-HT terminal autoreceptor activity was investigated with the selective h5-HT1B receptor ligands SB 219085, SB 220272, SB 224289 and SB 216641. The studies employed measurement of compound affinity and efficacy in vitro and the measurement of extracellular 5-HT in the frontal cortex of the freely-moving guinea-pig using in vivo microdialysis. All compounds had high affinity and selectivity for the h5-HT1B receptor, with SB 224289 the most selective for h5-HT1B over h5-HT1D receptors. Compounds exhibited a range of efficacies at both receptors: SB 224289 and SB 219085 were inverse agonists, SB 220272 was an antagonist and SB 216641 was a partial agonist. SB 220272, SB 216641 and SB 224289 had no effect on extracellular 5-HT following systemic administration, however, SB 219085 produced a significant increase. The SB 219085-induced increase in extracellular 5-HT was attributed to the compounds non-specific releasing properties as it was also demonstrated to increase basal release of [3H]5-HT from pre-loaded guinea-pig cortical slices. The lack of effect of the above h5-HT1B receptor selective compounds and the decrease in extracellular 5-HT elicited by the non-selective compounds GR 127935, GR125743 and methiothepin suggest that antagonism of 5-HT1D receptors may mediate this decrease in 5-HT levels. It is plausible that blockade of 5-HT1D receptors increases 5-HT levels in the raphe, this activates 5-HTtA receptors which results in an overall decrease in terminal 5-HT release. Definitive proof now awaits elucidation of the action of a selective 5-HT1D receptor antagonist.

Animals↗
PubMedDate not supplied

Gender and cancer support group participation.

PURPOSE: Although support groups are offered to many patients who have received a diagnosis of cancer, a majority of patients choose not to participate. This article reports the results of a study comparing the behavior of men diagnosed with prostate cancer and women diagnosed with breast cancer in their responses to invitations to participate in support groups. DESCRIPTION OF STUDY: One hundred thirty women with breast cancer and 87 men with prostate cancer completed a structured telephone interview. The interview included questions about the patients' choices about support group participation. RESULTS: Interview findings showed that men are less likely to join a support group, but those men who do join attend meetings for about 1 year, as do the women who join. Men and women cite essentially the same reasons for participation: to learn more about their diagnosis, to share their, concerns to compare their physical and emotional progress with other individuals. CLINICAL IMPLICATIONS: These results indicate the need for further exploration of effective interventions for men and women who have been diagnosed with prostate and breast cancer, respectively, in an effort to offer support for the difficult psychological and emotional issues associated with their diagnoses. Although more women than men join support groups, the majority of both populations (67% for women, 87% for men) do not attend any support group meetings. Innovative approaches are needed to encourage participation in existing support groups or to design alternative interventions.

Aged↗
PubMedDate not supplied

Simultaneous confirmation and differentiation of human T-lymphotropic virus types I and II infection by modified western blot containing recombinant envelope glycoproteins.

A modified Western blot (WB) that includes both shared (r21e) and unique recombinant envelope proteins from human T-lymphotropic virus (HTLV) type I (rgp46I) and type II (rgp46II) was compared to conventional HTLV serologic tests in 379 United States blood donors and individuals residing in diverse geographic regions, and the specimens were categorized as positive (n = 158), indeterminate (n = 158), or negative (n = 63) for HTLV infection. Of the 158 HTLV-I/II-positive specimens (66 requiring radioimmunoprecipitation assay [RIPA] for confirmation), 156 reacted concordantly with r21e, gag, and either rgp46I or rgp46II, thus eliminating the need for RIPA in all but two specimens and yielding a test sensitivity of 98.7 percent. Of the 158 indeterminate and 63 negative specimens, none reacted with r21e and rgp46I or rgp46II, yielding a test specificity of 100 percent. Furthermore, analysis of an additional 184 consecutive specimens from a retrovirology reference laboratory demonstrated that the modified WB correctly identified 27 of 28 HTLV-I specimens and all 13 HTLV-II specimens, with a test sensitivity of 97.6 percent. None of specimens that were indeterminate or nonreactive in conventional WB and/or RIPA and none of the screening enzyme immunoassay-negative specimens reacted with r21e and either rgp46I or rgp46II, for a test specificity of 100 percent. Thus, the modified WB appears to be highly sensitive and specific for simultaneous detection and discrimination of HTLV-I from HTLV-II and has the advantage of being a one-step assay that is easily performed in all types of laboratory settings and allows rapid, reliable, and standardized testing for HTLV-I/II infection.

Blood Donors↗
PubMedDate not supplied

Serial PBB levels, PCB levels, and clinical chemistries in Michigan's PBB cohort.

Half of a cohort of 3683 Michigan residents exposed to polybrominated biphenyls (PBBs) in 1973 and 1974 had 2 serum PBB determinations at a 1- or 2-yr interval. The median decrease in serum PBB levels during both 1- and 2-yr intervals was 1 microgram/L. The geometric mean serum polychlorinated biphenyl (PCB) level (6.3 microgram/L) exceeded that of PBB (4.1 micrograms/L), although the range of PCB levels (smaller than 1-57 microgram/L) was narrower than that of PBB levels (smaller than 1-3150 micrograms/L). Mean PCB and PBB levels were higher for males, and mean PCB levels increased with age. In a subgroup with higher-than-average PBB levels, serial clinical chemistry tests during 4 different years showed no consistent significant correlation with serum PBB levels. Tests with greater sensitivity and specificity for hepatic microsomal enzyme induction and thyroid status are needed in future evaluations of the most highly exposed subgroup of the cohort.

Adolescent↗
PubMedDate not supplied

Classroom and playground interaction of students with and without disabilities.

The classroom and playground behaviors of students with disabilities, in an integrated classroom, are frequently cited as reasons for rejection of these students by their regular-class peers. We compared the classroom and playground behavior of 95 students with mild disabilities with that of 95 students without disabilities, age and sex matched, and enrolled in the same classes. The children, age 8-13 years, attended state government elementary schools. Behaviors were observed using a time-sampling method with nine categories of behavior in each setting. The behavior of both groups of students was in many ways similar, regardless of the presence of disabilities.

Adolescent↗
PubMedDate not supplied

Factors influencing the social status of children with mild academic disabilities in regular classrooms.

This article discusses the development and evaluation of a model of social status which has implications for students both with and without mild academic disabilities in integrated classrooms. Behavioral data relating to peer social status were collected from peers, teachers, and independent observers for 97 students with disabilities and 97 without disabilities from the same regular elementary school classes. Path analysis indicated that teachers' attitudes toward integration were not related to the social status of the students with disabilities. However, teacher perceptions of academic behavior, peer perceptions of academic behavior, and peer perceptions of disruptive behavior were found to be related to social status for both groups of students.

Child↗