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Biomedical subjects

C R Schmidt

Publications and source records attributed to C R Schmidt.

14 recordsLinked to original sources
PubMed2001

Neurotransmitter-stimulated ion transport across cultured bovine mammary epithelial cell monolayers.

Bovine mammary epithelial (BME-UV) and myoepithelial (BMM-UV) cell lines were acquired with the goal of developing an in vitro model of mammary epithelia for the study of ion transport. The bovine mammary cell lines were successfully cultured on commercially available permeable supports, and results suggest that mammary epithelial cells, but not myoepithelial cells, form tight junctions necessary to perform a barrier function. Electrogenic ion transport was not observed in basal conditions. Acute exposure to norepinephrine or forskolin caused prototypic increases in short circuit current accompanied by a reduction in transmural resistance indicative of anion secretion through a conductive pathway. Bumetanide and N-(4-methyphenylsulfonyl)-N'-(4-trifluoro-methylphenyl)urea, inhibitors of Na+/K+/Cl- cotransport and cystic fibrosis transmembrane conductance anion channels, respectively, reduced forskolin-stimulated ion transport. Amiloride, an inhibitor of epithelial sodium channels, had no effect on basal or forskolin-stimulated ion transport. However, naturally occurring and synthetic corticosteroids induced the expression of amiloride sensitive current indicative of sodium absorption. Chronic exposure to increased apical ionic strength and/or reduced carbohydrate concentration were associated with reduced transepithelial resistance although forskolin-stimulated ion transport was unaffected. These results demonstrate that neurotransmitters and steroid hormones act directly on bovine mammary epithelial cells to acutely and chronically modulate the volume and composition of their secretions. The in vitro system that we describe can be further exploited to characterize cellular and molecular mechanisms associated with mammary function in health and disease.

Amiloride↗
PubMed1996

Gender-schema development and children's constructive story memory: evidence for a developmental model.

The objectives of the present research were to (a) provide a developmental model based on script research for describing how changes in memory for gender-related information are related to changes in gender-role stereotypes, (b) examine developmental differences in the effect of stereotype manipulations on the construction of new memories, and (c) examine the relation between stereotyped activity preferences and memory for gender-related information. 4-, 6-, and 8-year-olds listened to a story in which characters performed behaviors typical and atypical of gender-role stereotypes. An introduction preceded the story in which story characters' activities and preferences were described as either consistent or inconsistent with gender-role stereotypes. Dependent variables were the percentage of typical and atypical story items correctly recognized and the percentage of false alarms made for new items. Gender-role knowledge, stereotyped preferences, and gender-role flexibility were assessed. Results for false alarms, but not hit rates, supported the hypotheses of the model: (a) 6-year-olds falsely recognized typical distractors more than atypical distractors (this effect was nonsignificant for 4- and 8-year-olds), (b) false alarms for atypical distractors decreased between ages 4 and 6, and (c) false alarms for typical distractors decreased between ages 6 and 8. Contrary to expectation, stereotype manipulation effects did not interact with age, but were influenced by gender. Stereotyped preferences were strongly related to memory for gender-related information for both males and females. Results are discussed in terms of developmental and individual differences in gender-schema strength and composition.

Attention↗
PubMed1994

DNA variability and parentage testing in captive Waldrapp ibises.

The Waldrapp ibis (Geronticus eremita) is one of the most endangered birds in the wild. The only real hope for its survival seems to rest with captive propagation, which has fortunately proved straightforward. Preservation of genetic diversity for maintaining viable populations is a major goal in any species conservation programme. Therefore sensitive tools have to be developed for the detection and regular monitoring of population variability. Individual identity has to be verified and each individual's pedigree defined in order to enable effective selective breeding. In this study, extensive DNA fingerprinting technology was applied to a group of 39 captive Waldrapp ibises. Five minisatellite probes were used. Despite the fact that the colony was founded by only six birds and that some of the founders were apparently related, highly polymorphic banding patterns were obtained. The human- and pig-derived probes MS1, MS31, p lambda g3 and pCMS12 each detected multiple distinct loci suitable for individual identification and resolution of parentage. Probe MS51 was locus-specific and revealed six different alleles. In addition, MS31 and p lambda g3 co-detected a band present in all females but none of the males and thus could be used for sex determination. For all but four individuals both parents could be identified unambiguously. The exceptions were offspring derived from a full sib mating in which DNA results allowed no distinction between the parents and the grandparents. Comparison of the parentage assigned by DNA analysis and by observation of breeding behaviour, respectively, showed agreement in all but five instances. Here, DNA data uncovered interchange of individuals in the stud book. Application of these minisatellite probes therefore offers an extremely sensitive means for individual identification and verification and completion of pedigree records.

Animals↗
PubMed1992

Adoption of an additional infant by a Western lowland gorilla (Gorilla gorilla gorilla).

A 10-year-old Western lowland gorilla, already caring for her own 14-month-old son, adopted a female neonate. The infant's mother (aged 7 years, 4 months) showed no interest in the infant, and it is unclear whether she abandoned the infant or whether it was seized by the dominant foster-mother. The foster-mother gave more maternal attention to the adoptee than to her own son but gave both infants the same protection. She adjusted her forms of transport to the age of each infant. The subadult mother of the neonate did not seek contact with her offspring during the first 4 weeks and in fact showed more interest in the 14-month-old male infant. Interactions between the two mothers were rare. The foster-mother's own male infant died 2 months after she had adopted the female infant. She looked after the adopted infant for 1 year, but then lost interest so that the adoptee had to be separated.

Adoption↗
PubMed1990

Disseminated skeletal lesions associated with pathogenic actinomycetes in a Pygmy hog (Sus salvanius).

The clinical and pathological features of an unusual crippling bone disease in an adult male Pygmy Hog, Sus salvanius, born the smallest in a litter of five and representing the rarest of the known living Suidae, are described. Radiological studies revealed severe spondylosis deformans and focal sharply demarcated radiolucencies in virtually the whole skeleton, but particularly in the bones of the skull, the processes of multiple vertebrae, the ribs, scapulae and parts of the humeri and femora. The clinical chemistry measurements were indicative of pathological lytic processes in the skeleton. The focal bone lesions consisted of caseous necrosis, dystrophic calcification and peripheral fibroblastic demarcation. They contained colonies of filamentous bacteria identified as members of the Order Actinomycetales. Case history evidence suggests that the infection may have resulted from repeated skin trauma inflicted by litter-mates.

Actinomycetales Infections↗
PubMed1985

Elevated expression of the cellular src gene in tumors of differing etiologies in Xiphophorus.

In the fish Xiphophorus we have detected elevated levels of pp60c-src kinase activity in a variety of tumors (n = 34) of neurogenic, epithelial, and mesenchymal origin either of hereditary etiology or induced by carcinogens. This elevation ranged from 2-fold up to 50-fold compared to the corresponding non-tumorous tissue and up to 6-fold compared to the highest activities found in any of the normal organs. The level of elevation parallels the degree of malignancy in melanoma and in tumors of mesenchymal origin. In fish bearing tumors of hereditary etiology kinase activity was also elevated in the non-tumorous brain, while in fish bearing induced tumors, kinase activity was elevated only in the cells of the neoplasia.

Animals↗
PubMed1984

Continuous S-vO2 measurement and oxygen transport patterns in cardiac surgery patients.

Twenty adult cardiac surgery patients with impaired ventricular function by contrast ventriculography at cardiac catheterization were monitored from before anesthesia until the time of extubation up to 12 h postoperatively. A thermodilution pulmonary artery catheter with fiberoptic channels for continuous measurement of mixed-venous oxygen saturation (S-vO2) by reflection oximetry was substituted for the usual catheter. The S-vO2 was recorded continuously along with blood pressure, cardiac filling pressures, and heart rate. Thermodilution cardiac output determinations were used to derive hemodynamic and oxygen transport indices. There was a consistently high and significant negative correlation (r = -.84) between S-vO2 and the percentage of oxygen extracted from blood. Thus, S-vO2 reflects oxygen extraction and continuous S-vO2 provides continuous quantification of global oxygen extraction. None of the other oxygen transport variables including cardiac index showed significant correlation with S-vO2. The oximetry system provides a continuous and reliable indication of mixed-venous blood oxygenation which is a continuous reflection of oxygen extraction.

Aged↗
PubMed1981

Cytogenetics of neoplasia of Xiphophorus.

Certain laboratory hybrid Xiphophorus fish develop heritable neoplasia. Neoplasia can also be induced in some hybrids by treatment with carcinogens. In either case the neoplasms are mediated by a "'tumor gene," that is normally controlled by linked or nonlinked "regulating genes" or both. Light and electron microscopic studies on these two types of tumors reveal important differences. The heritable tumor is a compact mass of tissue formed of densely packed melanized melanocytes often with nuclear pockets and projections. A large number of cells undergoing a process of nuclear fragmentation has been observed. The induced tumors, on the other hand, contain fewer melanized melanocytes and show a comparative increase in the amount of connective tissue. The nuclear pockets and projections commonly found in the melanocytes of the heritable tumors are not present in the melanocytes of the induced melanoma. The most important difference observed was the presence of different types of structural chromosome aberrations in the induced tumor and a total absence in the heritable ones. These anomalies seem to be epiphenomenal, and the real genetic change is subchromosomal.

Animals↗
PubMed1978

Operativity and reversibility in children's understanding of pictorial sequences.

The role of reversibility in children's comprehension and memory for sequences of pictures was investigated. Bidirectionality in the ability to remember and infer antecedents and consequences was assessed. Preschoolers were significantly more accurate at identifying consequences of portrayed events than the antecedents. Kindergartners and older children correctly identified beginnings and endings of sequences with equal proficiency. This developmental shift from relatively unidirectional to reversible comprehension was observed both on trials involving figurative memory and operative inference judgments.

Child↗