Biomedical subjects

C Stern

Publications and source records attributed to C Stern.

At least 37 records · Page 2Linked to original sources

PubMed1994

[Self tonometry during the German 1993 Spacelab D2 mission].

Microgravity during space missions leads to a fluid shift from the lower to the upper parts of the body that also affects the intraocular pressure. In the early phase after reaching microgravity there is an intraocular pressure peak. In order to analyse the potential health risks for astronauts, a self-tonometer was developed to examine the early phase of microgravity. During the German-Russian MIR mission the equipment was tested for the first time in space. As one result we found an initial pressure increase of 92% compared to the baseline data values. In order to obtain more detailed information on the intraocular pressure alterations in space, similar equipment was used during the 10-day German Spacelab D2 mission. Two German scientists and one American astronaut obtained self-tonometric pressure profiles on 6 mission days (44 pressure values determined out of 144 measurements). The initial peak values 15 min after entering microgravity revealed pressure increase of 114% compared to the baseline data (average pressure: right eye 10.0 mmHg, left eye 9.9 mmHg; peak values: right eye 22.6 mmHg, left eye 22.2 mmHg). Pressure values exceeding the baseline data by more than 50% were registered up to the 3rd mission day. As to circadian rhythm, there was no difference between inflight data and baseline data before and after the mission.

Adult↗

PubMed1994

[Evaluation of current guidelines for flying capacity and internationally proposed revisions].

Despite several modifications of medical requirements for German flight personnel, these requirements have often been criticized by ophthalmologists because of their margins of interpretation. In many controversial cases regarding pilot licences, the final decision has to be made by the national aeromedical review board. The progress in ophthalmologic microsurgery, e.g. intraocular lens implantation and refractive surgery, has led to a certain insecurity among surgeons as to how to deal with these developments within the requirements. Besides, new cockpit designs with multiple colour displays have changed the demands on the pilot's visual system, especially with regard to colour perception. New European requirements which will probably become effective in 1994 are compared to the existing German standards.

Aircraft↗

PubMed1994

[Clarity of flight information in the cockpit of the new aircraft generation].

Fundamental changes of cockpit design in recent years, especially the transition from analogue to digital flight information systems and the use of colour-coded displays, lead to new demands on the visual system of the pilot. Twenty experienced pilots each participated in four 15-min sessions with a simulator program in the new Airbus 340 Simulator of the Technical University of Berlin. The pilots were confronted with various flight situations and events. The simulation program was carried out with visual acuity of 1.0 or better, with acuity reduced to 0.5 and with red and green filters. The time between the display of information and the pilot's reaction was determined. The probands were classified into two groups according to their age (< or = 45 years, > or = 45 years). In both age groups a significant difference was found only with green filters. There was no difference with reduced visual acuity or with red filters, and no differences were seen between the two age groups.

Adult↗

PubMed1993

Neuronal responses in the ventral striatum of the behaving macaque.

To analyse the functioning of the ventral striatum, the responses of more than 1,000 single neurons were recorded in a region which included the nucleus accumbens and olfactory tubercle in 5 macaque monkeys. While the monkeys performed visual discrimination and related feeding tasks, the different populations of neurons found included neurons which responded to novel visual stimuli; to reinforcement-related visual stimuli such as (for different neurons) food-related stimuli, aversive stimuli, or faces; to other visual stimuli; in relation to somatosensory stimulation and movement; or to cues which signalled the start of a task. The neurons with responses to reinforcing or novel visual stimuli may reflect the inputs to the ventral striatum from the amygdala and hippocampus, and are consistent with the hypothesis that the ventral striatum provides a route for learned reinforcing and novel visual stimuli to influence behaviour.

Amygdala↗

PubMed1993

Self-tonometry under microgravity conditions.

During a space mission flown in microgravity early changes in intraocular pressure due to the fluid shift effect in microgravity were analyzed with an automatic self-tonometer. In total, 13 pressure readings per eye were obtained during the mission. The first pressure readings 16 min after reaching microgravity revealed a 92% rise in intraocular pressure compared to the daytime-correlated baseline data on earth followed by an adaptation phase lasting for several hours. Diurnal pressure profiles during the mission showed no relevant difference in altitude and amplitude.

Humans↗

PubMed1992

Slowed lexical access in nonfluent aphasia: a case study.

A list priming paradigm (LPP) was used to examine the hypothesis that nonfluent aphasics are literally slowed down in automatic access to lexical information. In this paradigm, words are presented visually, and the subject's task is to make a lexical decision on each word as quickly as possible after its presentation. As soon as a lexical decision is made on one word, that word is removed and, after a predetermined interword interval, the next word is presented. In this way, a continuous "list" effect is obtained. Prior studies with both college-age and elderly subjects using the LPP have shown that, independently of age, on the LPP, priming obtains at interword delays of 500 to 800 msec, but not at either shorter or longer interword delays. In the study reported here, the LPP was used to examine delays at which priming obtained for LD, a nonfluent aphasic with a lesion primarily in the left frontal region. Examining interword delays ranging from 500 to 1800 msec, the subject showed priming only at a delay of 1500 msec, a considerably longer delay than that at which neurologically intact subjects have shown priming. Based on these results, it is argued that while automatic access is retained, that access is much slower in a nonfluent aphasic than in neurologically intact elderly subjects. These results are discussed in terms of how slowed lexical access might impact on discourse comprehension.

Aphasia, Broca↗

PubMed1992

[Cytogenetic subtyping of 139 uterine leiomyoma].

A cytogenetic study of 139 uterine leiomyomas of 70 patients is presented. 26 of the tumours failed to grow, 87 showed an apparently normal karyotype and 26 tumours were characterised by clonal aberrations. In 5 tumours, a numerical change was the only abnormality, including 2 tumours with a trisomy 12. 5 myomas showed an interstitial deletion of the long arm of chromosome 7. The largest group were 9 tumours with an aberration involving chromosome 12 in the band of 14-15. 2 myomas showed a t(12; 14) as the only abnormality, in 4 tumours very complex rearrangements with up to 12 breakpoints were observed. In the last group 7 myomas with other clonal aberrations involving 11 different chromosomes were found.

Animals↗

PubMed1992

The Royal Women's Hospital Family Birth Centre: the first 10 years reviewed.

In reviewing the first 10 years experience of the Royal Women's Hospital Family Birth Centre (FBC), we examined the outcomes of pregnancy and labour in a group of women who requested alternative birthing care and who were identified antenatally as being a 'low-risk' population. This study is a retrospective analysis of 5,365 women booked with the birth centre between 1980 and 1989. Over 16% of women developed antenatal complications precluding further care there, while a further 16% developed complications in labour requiring transfer out to conventional labour wards. Thus 67% of those originally booked delivered in the FBC. The instrumental delivery rate was 11%, and the Caesarean section rate was 4%. Of the women who delivered in the FBC, 3.1% had a postpartum haemorrhage and 1.8% required manual removal of placenta. Approximately 4% of babies born in the FBC required some resuscitation, and 0.8% needed admission to the neonatal nursery. Two perinatal deaths occurred in women admitted in labour to the FBC with a live baby, whilst 2 other women presented in labour with a fetal death in utero (perinatal mortality 0.89 per 1,000).

Birthing Centers↗

PubMed1992

Fetal alcohol syndrome: a case report of neuropsychological, MRI and EEG assessment of two children.

Neuropsychological, neuroanatomical, and electrophysiological data are presented on two subjects with fetal alcohol syndrome (FAS). Both boys had intelligence quotients in the mentally deficient range and were found to have several other severe, specific deficits. Magnetic resonance imaging showed abnormalities of the corpus callosum, and reductions in the size of the basal ganglia and thalamic structures. No focal abnormalities were noted in the electroencephalogram records, although the electroencephalograms of both boys were moderately abnormal for their age group. A multidisciplinary approach to the study of FAS, hopefully will lead to a more unified concept of the disorder and perhaps indicate specific areas of vulnerability.

Adolescent↗

PubMed1991

Leiomyoma cells with 12q15 aberrations can be transformed in vitro and show a relatively stable karyotype during precrisis period.

Tumor cells from three uterine leiomyomas showing translocations involving 12q14-15 were transformed by transfection using the "early regions" of the SV40 genome. The cells had a higher proliferative capacity, were able to form colonies in soft agar, and showed an increased growth potential. Karyotype analyses of these transformed leiomyoma cells showed that the cells had retained the initial t(12;14) and t(12;15).

Antigens, Polyomavirus Transforming↗

PubMed1991

Effects of mesodermal tissues on avian neural crest cell migration.

We have used microsurgical techniques to investigate the effects of embryonic mesodermal tissues on the pattern of chick neural crest cell migration in the trunk. Segmental plate or lateral plate mesenchyme was transplanted into regions encountered by neural crest cells. We found that neural crest cells are able to migrate through lateral plate mesenchyme but not through segmental plate tissue until this tissue differentiates into a sclerotome. After this stage, segmental migration is controlled by the subdivision of the sclerotome into a rostral and a caudal half; when the rostrocaudal orientation of the sclerotomes is reversed by rotating the segmental plate 180 degrees about its rostrocaudal axis, neural crest cells migrate through the portion of the sclerotome that was originally rostral.

Animals↗

PubMed1991

The time course of automatic lexical access and aging.

This study addresses the issue of cognitive slowing in the elderly by examining the time course of automatic lexical access. College-aged subjects typically show a brief rise time (300-500 msec) for lexical access. In the present study, we examine whether there are changes in rapid, automatized access routines with age. Elderly and college-aged subjects performed a lexical decision task wherein semantically related words embedded in a continuous list were presented one at a time with a varying (300-1500 msec) inter-word interval. The use of a continuous list, a repeated word, and a very short inter-stimulus interval allowed automatic lexical access to be straightforwardly examined. The elderly subjects showed an onset of automatic lexical access that was similar in time frame to that for college-age subjects. These findings suggest that wherever the locus of age-related slowing may be, it is not in the early, language-specific processing devices that mediate lexical access.

Adult↗

PubMed1991

The determination of nitroaromatics and nitramines in ground and drinking water by wide-bore capillary gas chromatography.

A method has been developed to determine the concentration of nitroaromatics and nitramines in drinking water at levels below those previously achieved by gas chromatography. The nitroaromatics and nitramines are extracted from water using toluene and isoamyl acetate, respectively. The extracts are analyzed via a gas chromatograph equipped with a DB-1301 widebore fused-silica capillary column and an electron capture detector. Method detection limits of 0.003 micrograms/L for 2,6-dinitrotoluene (2,6-DNT), 0.04 micrograms/L for 2,4-dinitrotoluene (2,4-DNT), 0.06 micrograms/L for 2,4,6-trinitrotoluene (TNT), 0.3 micrograms/L for cyclotrimethylenetrinitramine (RDX), and 6.0 micrograms/L for cyclotetramethylenetetranitramine (HMX) have been obtained using this method.

Azocines↗

PubMed1991

Elements for a theory of the health transition.

This article presents the basic elements for developing a theory of the health transition. Such elements include the definition of concepts, the specification of a framework on the determinants of health status, the analysis of the mechanisms through which health change occurs in populations, the characterization of the attributes that allow us to identify different transition models, and the enumeration of the possible consequences of the transition. The propositions are presented with a sufficient level of generality as to make them applicable to different contexts; at the same time, an attempt is made to provide them with the necessary specificity to account for different national experiences, thus opening a space for future comparative research efforts. Through the systematization exercise presented in this article, we hope to contribute to the progress of a topic that has grown in importance during recent years. Such importance is due to the enormous potential that health transition theory has for understanding and transforming the growing complexity of our times.

Demography↗

PubMed1991

[The epidemiologic transition in Latin America].

The concept of health transition is considered to include two interrelated processes: transition of health care and epidemiological transition. The latter encompasses three basic processes: (a) replacement of the common infectious diseases by noncommunicable diseases and injuries as the leading causes of death; (b) a shift in peak morbidity and mortality from the young to the elderly; and (c) change from a situation in which mortality predominates in the epidemiological panorama to one in which morbidity is dominant. Latin America is characterized by a heterogeneous health profile in which different countries are in various stages of epidemiological transition. However, in most of them, the transition experience is unlike that of the developed countries and is distinguished by: (a) a simultaneous high incidence of diseases from both the pre- and post-transitional stages; (b) a resurgence of some infectious diseases that had previously been under control; (c) a lack of resolution of the transition process, so that the countries appear to be caught in a state of mixed morbidity; (d) a peculiar epidemiological polarization, not only between countries but also in the different geographical areas and between the various social classes of a single country. This experience is called a "prolonged polarized model."

Adolescent↗

PubMed1990

Pleomorphic adenomas with unbalanced chromosomal abnormalities have an increased in vitro lifetime.

The in vitro lifetime of 100 salivary gland pleomorphic adenomas was investigated. On the average, they had a limited lifetime of 3.7 passages. In 86 cases, the tumors were successfully karyotyped, resulting in three major cytogenetic subgroups characterized by either an apparently normal karyotype or by rearrangements of 8q12 or 12q13-15. There was no significant difference between the in vitro lifetime of the tumors with a normal or with an aberrant karyotype. The three adenomas with the longest lifetime were characterized by an unbalanced karyotype. One of them had a deleted chromosome 6, which has also been described in malignant tumors. An increased in vitro lifetime may thus correspond to early steps of malignant transformation in vivo and can be caused by additional unbalanced chromosome aberrations. In the future, long-term cultivation can be helpful in defining chromosomal regions involved in this process.

Adenoma↗

PubMed1990

Segmentation and the development of the vertebrate nervous system.

1. Recent experiments on the development of neural segmentation in chick embryos are reviewed. 2. Segmentation of the spinal peripheral nerves is governed by a subdivision of the somite-derived sclerotome into anterior and posterior halves. Migrating neural crest cells and outgrowing motor axons are confined to the anterior sclerotome as a result, in part, of inhibitory interactions with posterior sclerotome cells. 3. The sclerotomal distribution of certain molecules known to influence growing nerve cells in vitro, namely laminin, fibronectin, N-CAM, N-Cadherin and J1/tenascin/cytotactin, suggest that these molecules play no critical role in determining the preference of nerve cells for anterior sclerotome. 4. Peanut agglutinin (PNA) recognises cell surface-associated components on posterior cells which, when incorporated into liposomes, cause the abrupt collapse of sensory growth cones in vitro. The PNA receptor(s) may be inhibitory for nerve cells in vivo. 5. The chick hindbrain epithelium is segmented early in its development. Each branchiomotor nucleus in the series of cranial nerves V, VII and IX derives from a pair of segments lying in register with an adjacent branchial arch. Neurogenesis of motor and reticular axons begins in alternate segments, suggesting parallels with insect pattern formation.

Animals↗

PubMed1989

Teen Advocate Program: a unique assessment of case management.

The Teen Advocate Program is a case management demonstration project developed with a block grant from the Maternal and Child Health Section of the Louisiana Department of Health. Family Counseling of East Baton Route Parish, a community-based agency, was contracted to develop outreach services for high risk adolescents. The purpose of the program is to provide structure, advocacy, and coordination, empowering teens to use primary and preventive health care providers. The initial referral base of clients was provided from a clinic of teen mothers and their infants, and an adolescent family planning clinic, both located at the East Baton Rouge Parish Health Unit. This interdisciplinary case management outreach services makes this model unique because it offers an organized, structured preventive health care intervention to teens at high risk of becoming pregnant. Goal attainment scales developed revealed that 96% of the study population improved. Sixty-seven percent have good attendance at clinics. Among the client population of teen mothers, there has only been a 4% repeat pregnancy rate. For the first six months of existence, there were no documented pregnancies among the adolescent seeking contraceptive counseling. The study results confirmed the positive influence of case management in preventing adolescent pregnancy. This model is being expanded to address other high risk adolescent behaviors.

Adolescent↗