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Biomedical subjects

L Richter

Publications and source records attributed to L Richter.

At least 37 records · Page 2Linked to original sources
PubMed2000

Thioredoxin, a putative oncogene product, is overexpressed in gastric carcinoma and associated with increased proliferation and increased cell survival.

Human thioredoxin is a putative oncogene that may confer both a growth and survival advantage to tumor cells. Overexpressed thioredoxin mRNA has been found in both primary human lung and colorectal cancers. To determine the intratumor distribution and amount of thioredoxin protein in human primary carcinomas, we developed an immunohistochemical assay for thioredoxin in paraffin-embedded tissue. We then studied 10 patients with primary high-risk gastric carcinoma. To further relate thioredoxin protein overexpression to cell death and survival, we used a paraffin-based in situ end-labeling (ISEL) assay. To delineate proliferation, we used the nuclear proliferation antigen detected by Ki-67. In this survey, we found that thioredoxin was localized to tumor cells and overexpressed compared with normal gastric mucosa in 8 of 10 gastric carcinomas. The thioredoxin was found at high levels in 5 of the 8 overexpressing carcinomas. The overexpression of thioredoxin was typically found in both a nuclear and cytoplasmic location in the neoplastic cells. There was a significant positive correlation (P = .0061) with cancer cell proliferation measured by Ki-67. There was a significant negative correlation (P = .0001) with DNA damage measured by the ISEL assay, suggesting decreased apoptosis and increased carcinoma cell survival. Thus, human primary gastric tumors that are highly expressive of thioredoxin have both a higher proliferative rate and a higher survival rate than tumors that do not express thioredoxin. With these newly developed assays in hand, it is now feasible to question whether this thioredoxin-related combined growth and survival advantage translates into poor clinical outcome.

Adenocarcinoma↗
PubMed2000

Needle sharing: a longitudinal study of female injection drug users.

The objective of this study was to examine the psychosocial risk and protective factors related to needle-sharing behavior among female intravenous drug users (IDUs) positive (N = 96) and negative (N = 128) for human immunodeficiency virus (HIV). Participants in this longitudinal study were interviewed individually at two points in time, with a 6-month interval between interviews. The interviewers used a structured questionnaire, which included psychosocial measures and questions about drug and sexual risk behaviors. Data were analyzed using Pearson correlations and hierarchical regression analyses. The findings supported a developmental model in which the psychosocial domains and HIV status predicted T1 (initial) needle-sharing behavior, which in turn was related to T2 (follow-up) needle-sharing behavior. In addition, the relationship between personality and peer risk factors and T2 needle sharing was buffered by family-related protective factors. While HIV-positive status had a direct effect on T1 needle sharing with strangers, its effect was mediated by all of the psychosocial variables in its relation to T1 needle sharing with familiar people. Comparisons of these results were made with a companion study of male IDUs. The results suggest several intervention and treatment approaches that can be implemented at different points in the developmental pathways leading to risky needle-sharing practices among female IDUs.

Adult↗
PubMed2000

Effects of parent personality, upbringing, and marijuana use on the parent-child attachment relationship.

OBJECTIVE: To examine the predictors of the quality of the parent-child attachment relationship among a sample of 248 young adults with children. METHOD: In this longitudinal study, data were collected during early adulthood in 1992 and in 1996/1997 via a structured questionnaire. Using logistic regression and multiple regression analyses, the authors assessed the extent to which participants' personality attributes, substance use, and relationships with their mothers predicted the quality of the parent-child bond. RESULTS: Logistic regression models showed that participants with certain personality attributes (e.g., high sensitivity), less frequent marijuana use, or a close relationship with their mothers had a greater likelihood of having a close parent-child attachment relationship with their own children at a later time. Regression analysis also showed that the risk of earlier substance use on the parent-child relationship was offset by protective factors in the parents' personality domain. In addition, protective factors in the various parental domains synergistically interacted with a low frequency of marijuana use, relating to a closer parent-child attachment relationship. CONCLUSIONS: The findings suggest that certain parenting styles are transmitted across generations and interventions in the personality and drug use domains can help increase the likelihood that parents will form close attachment relationships with their own children.

Adolescent↗
PubMed2000

Consequences of adolescent drug use on psychiatric disorders in early adulthood.

This article summarizes the existing literature on the relationship between adolescent drug use and abuse and the development of psychiatric disorders in adulthood. In recent years, there has been increased awareness of the co-occurrence of drug abuse and psychiatric disorders in adolescence and young adulthood. Few longitudinal studies, however, have examined specifically the impact of earlier drug use and abuse on later psychiatric disorders. The literature suggests three possible models to explain the relation between drug use and abuse and psychiatric disorders. According to the first model, adolescent psychiatric disorders precede drug use and abuse. A second model postulates that psychiatric disorders and drug use are correlated because they share one or more common aetiological factor(s). The third model posits that drug use and abuse predict or precede certain psychiatric disorders. We present data from a recent longitudinal study to support this latter model. As drug use and abuse have been shown to increase the likelihood of psychiatric disorders, it is clear that medical attention needs to be given to adolescents who use drugs of abuse. It is expected that a decrease in adolescent drug abuse should lead to an accompanying reduction in later psychiatric disorders.

Adolescent↗
PubMed2000

Cardiovascular disease risk factors in 5-year-old urban South African children--the Birth to Ten Study.

BACKGROUND: A birth cohort study, the Birth to Ten (BTT) study, commenced in the greater Johannesburg/Soweto metropole in South Africa in 1990. The overall BTT project collected antenatal, birth and early development information on these children as well as information that could help identify factors related to the emergence of risk of cardiovascular diseases (CVDs) in children. OBJECTIVE: To determine CVD risk profiles and their determinants in 5-year-old children living in an urban environment in South Africa. METHODS: Demographic and birth characteristics were collected on a sample of 964 5-year-olds whose parents agreed for blood samples to be taken from their children. The children's height and weight were measured using standardised procedures; blood pressure (BP) was measured with a Dinamap Vital Signs Monitor, and a non-fasting blood sample was drawn for lipid determinations. Information on exposure to tobacco smoke and additional health-related data were obtained by interview. RESULTS: No differences were found between the birth weight and gestational age of the 5-year-old CVD participants and the remainder of the children studied at birth. The systolic BP was significantly different between ethnic groups, with the BP of the black children significantly higher than that of the Indian and white children, while the diastolic BP of black children was also the highest. White children had the highest mean total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC) levels, significantly higher than those in the black community. The coloured children's TC level was also significantly lower than that of the whites, while the LDLC level of the Indian children was significantly higher than that of the blacks. Overall, 64% of the children were exposed to environmental tobacco smoke (ETS), with the white group having the lowest rate (45% exposed to ETS). The coloured children were most frequently exposed to ETS, with 40.6% having primary caregivers who smoked; of these children 42% lived in homes with two or more smokers. CONCLUSIONS: Tobacco control legislation will protect South Africans against tobacco sales promotions. This will be the first step towards increasing the priority of chronic disease prevention, health promotion and appropriate care for chronic diseases and their risk factors on the South African health policy agenda. The groups of children that were studied carried differing but significant levels of CVD risk. This suggests that the promotion of a healthy lifestyle should start in childhood, and should target the risk factors found in each group.

Analysis of Variance↗
PubMed2000

Ethical issues in HIV vaccine trials in South Africa.

In this review we describe the ethical issues central to local and international debates about HIV vaccine trials. These issues include the physiological and psycho-social risks of trial participation, the preventative interventions to be provided to participants, access to treatment for participants who seroconvert, access to an effective vaccine after the trial, the role of placebo-controlled trials, and obtaining informed consent.

AIDS Vaccines↗
PubMed1999

Expression of vascular endothelial growth factor and its receptors in hematopoietic malignancies.

Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis by acting as a potent inducer of vascular permeability as well as serving as a specific endothelial cell mitogen. The importance of angiogenic factors such as VEGF, although clearly established in solid tumors, has not been fully elucidated in human hematopoietic neoplasms. We examined the expression of mRNA and protein for VEGF in 12 human hematopoietic tumor cell lines, representing multiple lineages and diseases, including leukemia, lymphoma, and multiple myeloma. Our results revealed that VEGF message was expressed in these cells and that the corresponding protein was secreted into the extracellular environment. Five of the 12 cell lines were also found to express the Flt-1 receptor for VEGF at a moderate to strong level, suggesting an autocrine pathway. When human vascular endothelial cells were exposed to recombinant human VEGF, there was an increase in the mRNA for several hematopoietic growth factors including macrophage colony-stimulating factor, granulocyte colony-stimulating factor and interleukin 6. Plasma cells in the bone marrow from patients diagnosed with multiple myeloma were found to express VEGF, whereas both the Flt-1 and KDR high affinity VEGF receptors were observed to be markedly elevated in the normal bone marrow myeloid and monocytic cells surrounding the tumor. These data raise the possibility that VEGF may play a role in the growth of hematopoietic neoplasms such as multiple myeloma through either a paracrine or an autocrine mechanism.

Adult↗
PubMed1999

Chlorobium ferrooxidans sp. nov., a phototrophic green sulfur bacterium that oxidizes ferrous iron in coculture with a "Geospirillum" sp. strain.

A green phototrophic bacterium was enriched with ferrous iron as sole electron donor and was isolated in defined coculture with a spirilloid chemoheterotrophic bacterium. The coculture oxidized ferrous iron to ferric iron with stoichiometric formation of cell mass from carbon dioxide. Sulfide, thiosulfate, or elemental sulfur was not used as electron donor in the light. Hydrogen or acetate in the presence of ferrous iron increased the cell yield of the phototrophic partner, and hydrogen could also be used as sole electron source. Complexed ferric iron was slowly reduced to ferrous iron in the dark, with hydrogen as electron source. Similar to Chlorobium limicola, the phototrophic bacterium contained bacteriochlorophyll c and chlorobactene as photosynthetic pigments, and also resembled representatives of this species morphologically. On the basis of 16S rRNA sequence comparisons, this organism clusters with Chlorobium, Prosthecochloris, and Pelodictyon species within the green sulfur bacteria phylum. Since the phototrophic partner in the coculture KoFox is only moderately related to the other members of the cluster, it is proposed as a new species, Chlorobium ferrooxidans. The chemoheterotrophic partner bacterium, strain KoFum, was isolated in pure culture with fumarate as sole substrate. The strain was identified as a member of the epsilon-subclass of the Proteobacteria closely related to "Geospirillum arsenophilum" on the basis of physiological properties and 16S rRNA sequence comparison. The "Geospirillum" strain was present in the coculture only in low numbers. It fermented fumarate, aspartate, malate, or pyruvate to acetate, succinate, and carbon dioxide, and could reduce nitrate to dinitrogen gas. It was not involved in ferrous iron oxidation but possibly provided a thus far unidentified growth factor to the phototrophic partner.

Bacteria, Anaerobic↗
PubMed1999

Beagle 2: a proposed exobiology lander for ESA's 2003 Mars Express mission.

The aim of the proposed Beagle 2 small lander for ESA's 2003 Mars Express mission is to search for organic material on and below the surface of Mars and to study the inorganic chemistry and mineralogy of the landing site. The lander will have a total mass of 60kg including entry, descent, and landing system. Experiments will be deployed on the surface using a robotic arm. It will use a mechanical mole and grinder to obtain samples from below the surface, under rocks, and inside rocks. Sample analysis by a mass spectrometer will include isotopic analysis. An optical microscope, an X-ray spectrometer and a Mossbauer spectrometer will conduct in-situ rock studies.

Equipment Design↗
PubMed1999

Adversity and psychosocial competence of South African children.

Black children in South Africa commonly experience low socioeconomic status and community violence. Parents (N = 625) in a longitudinal study of urbanization responded to structured questionnaires related to resilience, affability, maturity, and school readiness of their six-year olds. SES was found to have an inverse and linear relation to competence at age six; the relationship to violence was curvilinear, with children from moderately safe communities achieving better outcomes than those from very safe or very unsafe ones.

Achievement↗
PubMed1999

Consequences of adolescent marijuana use: incompatibility with the assumption of adult roles.

This longitudinal study is an examination of the relationship between marijuana use and the assumption of adult roles, as well as the relationship between assuming adult roles and the likelihood of later marijuana use. Data were collected at 5 points in time from childhood through early adulthood (late 20s) by means of a structured questionnaire. Participants' marijuana use and the assumption of adult roles, including employment, marriage, parenthood, and living arrangements, were measured, and the data were analyzed with logistic regression analyses. A history of marijuana use was associated with an increased risk of adopting more unconventional adult roles, such as postponement of marriage, having a child out of wedlock, and unemployment. These results suggest that frequent prior marijuana use may adversely affect one's ability to successfully assume conventional adult roles. Furthermore, controlling for earlier marijuana use, marriage during early adulthood significantly decreased the risk of later marijuana use.

Adolescent↗
PubMed1999

Coping strategies of HIV-positive and HIV-negative female injection drug users: a longitudinal study.

This study longitudinally examined the psychosocial correlates of coping strategies among 165 HIV positive and 179 HIV negative female injection drug users (IDUs). Participants were interviewed twice using a structured questionnaire, with a 6-month interval between interviews. The questionnaire included psychosocial measures as well as measures of general coping and specific HIV-related coping. Data were analyzed using logistic regression analyses. The findings indicated that favorable factors in the psychosocial domains at Time 1 were significantly associated with an increased likelihood at Time 2 of the use of general coping and specific adaptive coping strategies, such as problem solving and seeking social support, and with a decreased likelihood at Time 2 of the use of maladaptive coping strategies, such as aggression and the use of illicit drugs. These findings highlight particular areas of psychosocial functioning that can be targeted by intervention programs to promote adaptive coping and minimize maladaptive coping among HIV positive and HIV negative female IDUs.

Adaptation, Psychological↗
PubMed1998

Lactobacillus amylolyticus sp. nov., isolated from beer malt and beer wort.

Some of the strains used for the biological acidification in breweries belong to L. delbrueckii subsp. delbrueckii, L. delbrueckii subsp. lactis or L. fermentum. However, more recent studies showed that most strains isolated are physiologically different from the above mentioned species and were tentatively allocated to Lactobacillus amylovorus. Genotypic studies of 25 strains exclusively isolated from beer malts and beer worts, showed, that there were differences to the type strain of L. amylovorus concerning DNA-DNA similarities and the sequences of their 16S and 23S rRNA genes. Therefore, we propose to combine these strains in a new species of the genus Lactobacillus, namely L. amylolyticus. Strain DSM 11664 is proposed as the type strain. An rRNA targeted oligonucleotide probe was designed that allows a fast and reliable identification of Lactobacillus amylolyticus.

Bacterial Typing Techniques↗
PubMed1998

Staphylococcus condimenti sp. nov., from soy sauce mash, and Staphylococcus carnosus (Schleifer and Fischer 1982) subsp. utilis subsp. nov.

Based on the sequence data of 23S rRNA of Staphylococcus carnosus, Staphylococcus piscifermentans, Staphylococcus aureus and Staphylococcus epidermidis, species-specific probes were constructed. Their application revealed a heterogeneity within 18 strains previously identified as S. carnosus. Strains of this group were selected, and their 23S rRNA sequence was determined. It was revealed that the strains of S. carnosus can be placed in at least three sub-groups. This grouping was supported by physiological data and DNA-DNA similarity studies. Based on these results, were propose the new species Staphylococcus condimenti sp. nov. The type strain is S. condimenti F-2T (=DSM 11674T). The phylogenetic position of the new species within the radiation of other staphylococcal strains is reflected by a 16S nRNA-based tree. Furthermore, it is proposed to designate the new subspecies of Staphylococcus carnosus Schleifer and Fischer 1982, Staphylococcus carnosus subsp. utilis subsp. nov. The type strain of S. carnosus subsp. utilis is SK 11T (= DSM 11676T).

Base Sequence↗
PubMed1997

[Involvement of the creatine kinase test in the selection scheme of pig breeding programs].

With the increase of meat-quantity in the German pig-breeds in the sixties and seventies, more and more deficiency in meat-quality and stress appeared. It is based on a latent exertional myopathy. A result is an increase of Creatin-Kinase in the blood-plasma. It can be investigated by an analysis in a laboratory. The results from this analysis supplies us with information about the susceptibility to stress of the investigated pig. This physiological proceeding is consistently used in the CK-test to select stress-stable pigs. In HULSENBERG this test is used since the end of the seventies with great success.

Animal Husbandry↗
PubMed1996

Transgenic Plants Created for Oral Immunization Against Diarrheal Diseases.

We have created transgenic plants that express subunit antigens of infectious bacteria and viruses. These proteins have been isolated and characterized to demonstrate that they retain immunogenic properties. When raw potatoes containing the recombinant immunogens were fed to mice, the animals were orally immunized. Research completed to date has demonstrated the feasibility of using a genetically-engineered food as an inexpensive oral vaccine production and delivery system for diarrheal disease. The system could be a convenient means to deliver vaccines to travelers. It also has great potential as an appropriate technology for producing vaccines "in country" in the developing world. This review focuses on work from our group on recombinant subunit vaccines in potato tubers against enterotoxigenic Escherichia coli and Norwalk virus.

Journal Article↗
PubMed1996

Development of an orthotopic SCID mouse-human tumor xenograft model displaying the multidrug-resistant phenotype.

Multiple myeloma is a plasma cell malignancy which is generally incurable in spite of a high initial response to chemotherapy. While animal models of myeloma are known, the recent developments of human xenografts in nude and SCID mice suggests a promising experimental model. The SCID model, in particular, holds promise because these animals readily accept hematopoietic and lymphoid transplantation and do not generally develop graft versus host reaction. We have developed two drug-resistant variants of the human multiple myeloma cell line ARH-77 by in vitro exposure to gradually increasing concentrations of doxorubicin (ARH-D60) or mitoxantrone (ARM-80). When injected into irradiated SCID mice, the ARH-D60 cell line grew in an orthotopic pattern with the development of osteolytic lesions. This is in contrast to the 8226/C1N human myeloma cell line which grows in a disseminated but nonorthotopic manner in the SCID mouse. Both the ARH-D60 and ARM-80 cell lines are resistant to doxorubicin and cross-resistant to mitoxantrone, vinca alkaloids, taxol and m-AMSA while maintaining sensitivity to antimetabolites and alkylating agents. Growth characteristics and cell cycle kinetics, including S-phase, were not altered in the resistant sublines. The ARH-D60 and ARM-80 cell lines both displayed a classic multidrug-resistance (MDR) phenotype which was partially reversed by the addition of verapamil. These two cell lines represent the first MDR human myeloma cell lines which have demonstrated an orthotopic growth pattern in the SCID mouse and thus may be of value in studying the pathophysiology of this disease.

Animals↗