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Biomedical subjects

G Peters

Publications and source records attributed to G Peters.

429 records · Page 24Linked to original sources
PubMedDate not supplied

Androgen regulation of cell proliferation and expression of viral sequences in mouse mammary tumour cells.

The role of steroids in promoting cell proliferation is well established but the molecular mechanisms are not clear. The S115 mouse mammary tumour cell line provides a model system for molecular studies in vitro in that it exhibits in tissue culture both a positive proliferative response to androgens and a change from a transformed phenotype in the presence of androgen to a normal phenotype when androgen is removed. We have considered here the possible involvement of mouse mammary tumour virus (MMTV) in these processes. We have demonstrated the presence in S115 cells of MMTV-related sequences which are transcribed into RNA only in the long-term presence of androgen. Prolonged culture in the absence of androgen, which results in loss of proliferative response to androgen, is accompanied by loss of MMTV-related RNA and increased methylation of MMTV-related sequences.

Animals↗
PubMedDate not supplied

Activation of cellular gene by mouse mammary tumour virus may occur early in mammary tumour development.

There is now good evidence that the induction of mammary carcinomas by mouse mammary tumour virus (MMTV) involves provirus activation of specific cellular genes. Thus, a high percentage of virally induced tumours contain an acquired MMTV provirus in either of two defined integration regions, termed int-1 and int-2, and provirus insertion is accompanied by expression of specific RNA transcripts from these regions. We show here that in some recurring, pregnancy-dependent mammary tumours provirus integration within int-2 has already occurred at the earliest appearance of the tumour and may therefore represent an important step in the development of neoplasia. As judged by the distribution of the acquired MMTV proviruses, the tumours recurring at any one site represent the same clonal population of cells as the original tumour and remain clonal during cycles of proliferation and regression, including the transition to hormone-independent status. These data suggest that either the expression of the int-2 locus or the function of this putative oncogene must remain responsive to hormones and that some additional event must be responsible for the transition to autonomous growth.

Age Factors↗
PubMedDate not supplied

Concerted activation of two potential proto-oncogenes in carcinomas induced by mouse mammary tumour virus.

The induction of tumours by retroviruses lacking transduced oncogenes can involve the transcriptional or functional activation of cellular proto-oncogenes by an integrated provirus. Thus, the two cellular genes int-1 and int-2, identified as common targets for activation by mouse mammary tumour virus (MMTV), may constitute previously unrecognized oncogenes. In tumours, proviral insertion at these loci leads to expression of messenger RNAs which are undetectable in normal mammary glands. Here we report that in a survey of the two transcriptional activity and structural integrity of the two int loci in 30 BR6 mouse mammary tumours, around 50% of the tumours expressed both of these genes, in ostensibly monoclonal cell populations. Our data suggest that int-1 and int-2 may act cooperatively in the genesis of mammary carcinomas. However, because three tumours (10%) involved neither gene, and because in five cases activation occurred in the apparent absence of an adjacent provirus, it is clear that other loci and mechanisms contribute to tumorigenesis.

Animals↗
PubMedDate not supplied

[Thought protocols before and after a psychological headache--treatment with imagery].

Cognitive changes accompanying a headache treatment with imagery strategies were investigated. 15 female and 6 male headache sufferers with migraine (6), tension-type headache (7) or both (8) wrote down their thoughts during 1-5 headache episodes, kept a headache diary and filled in several pain questionnaires before and after treatment. After treatment there were significantly more positive and less negative thoughts. Pain frequency, duration, medication intake intensity, catastrophizing and helplessness were reduced, self-efficacy was enhanced. Changes of thought protocol variables were correlated with treatment effects. The role of cognitive changes in the psychological treatment of chronic headache is discussed.

Adult↗
PubMedDate not supplied

[Comparison of knee ligament scores and rating systems].

The results of the treatment of knee instabilities are evaluated by different scoring systems including subjective and/or objective criteria. Because of their number and their different criteria a comparison between the scoring systems is still a problem. The aim of this study was to analyze 14 different scoring-systems and prove the comparison of the commonly used rating scales. 116 patients with anterior or anterior-medial knee instabilities were followed up at least 2 years postoperatively. The evaluation was performed according to the criteria of the used rating-scales. The Lysholm I scoring system showed the highest mean total score (92 points). The scales that gave the highest correlation were the Cincinnati and ARPEGE scoring system (r = 0.97). The Lysholm I Scale and the Barrack Scale correlated least well (r = 0.711). This study documents that a transfer of results from one scoring system to another is not possible. A comparison between these scoring systems is only possible after adjusting the total points, the quality and the quantity of each criterion and component of the scoring system. This can done by using a standardized rating scale like the IKDC-score.

Activities of Daily Living↗
PubMedDate not supplied

Ceftriaxone monotherapy in the treatment of low-risk febrile neutropenia.

UNLABELLED: Febrile neutropenia in patients who have undergone chemotherapy is usually treated with a combination of broad-spectrum antibiotics. There are no exactly defined protocols for single-agent treatment because a clear definition of low risk febrile neutropenia is lacking. This paper examines the safety and efficacy of once-daily ceftriaxone in 376 cases. MATERIAL AND METHODS: In a prospective observational study carried out between February 1992 and January 1996, 959 febrile episodes at 48 hospitals were recorded. Inclusion criteria were neutropenia (absolute neutrophil count, ANC <1,000/ microl) with fever (>/=38.5 degreesC) or a C-reactive protein concentration >1 mg/dl and suspected infection. Nine hundred and one episodes (acute leukemia n = 396, lymphoma n = 220, solid tumors n = 272 and other disorders n = 13) in 828 patients aged between 1 and 97 years were analyzed, of which 876 episodes were evaluable for response. All patients initially underwent empirical treatment with ceftriaxone (adults: 2 g/day; children: 80 mg/kg/day), either alone (376) or in combination with other agents (525). RESULTS: The mean ANC was 423/ microl (SD +/- 316) and the median duration of neutropenia 10 days. Of the 363 episodes treated initially with ceftriaxone alone, 70.8% responded versus 56.9% in the combination therapy group. The favorable response to the initial monotherapy treatment was explained by a low-risk population in the monotherapy group. A KI >6 (p < 0.0001), ANC >/=500/ microl (p = 0.0001) and a duration of ANC <5 days (p < 0.05) were significantly more frequent in the monotherapy arm and were predictive of lower risk at the commencement of treatment. CONCLUSION: Ceftriaxone is effective in febrile neutropenia. Treatment with ceftriaxone alone was safe and highly effective in low-risk patients. Single-agent regimens appear to be a suitable treatment option in low-risk febrile neutropenia.

Adolescent↗
PubMedDate not supplied

Biomechanical properties and vascularity of an anterior cruciate ligament graft can be predicted by contrast-enhanced magnetic resonance imaging. A two-year study in sheep.

Magnetic resonance imaging has been used to determine graft integrity and study the remodeling process of anterior cruciate ligament grafts morphologically in humans. The goal of the present study was to compare graft signal intensity and morphologic characteristics on magnetic resonance imaging with biomechanical and histologic parameters in a long-term animal model. Thirty sheep underwent anterior cruciate ligament reconstruction with an autologous Achilles tendon split graft and were sacrificed after 6, 12, 24, 52, or 104 weeks. Before sacrifice, all animals underwent plain and contrast-enhanced (gadolinium-diethylenetriamine pentacetic acid) magnetic resonance imaging (1.5 T, proton density weighted, 2-mm sections) of their operated knees. The signal/noise quotient was calculated and data were correlated to the maximum load to failure, tensile strength, and stiffness of the grafts. The vascularity of the grafts was determined immunohistochemically by staining for endothelial cells (factor VIII). We found that high signal intensity on magnetic resonance imaging reflects a decrease of mechanical properties of the graft during early remodeling. Correlation analyses revealed significant negative linear correlations between the signal/noise quotient and the load to failure, stiffness, and tensile strength. In general, correlations for contrast-enhanced measurements of signal intensity were stronger than those for plain magnetic resonance imaging. Immunohistochemistry confirmed that contrast medium enhancement reflects the vascular status of the graft tissue during remodeling. We conclude that quantitatively determined magnetic resonance imaging signal intensity may be a useful tool for following the graft remodeling process in a noninvasive manner.

Animals↗
PubMedDate not supplied

Non-invasive 27-hour blood pressure registration including dental checkups in some dental practices.

The study involved 53 patients aged 18 to 67 (mean age 38.8, SD 13.6), 26 male and 27 female, who were monitored by means of a 27-hour non-invasive ambulant blood pressure registration, using the Oxford Monitoring System. All patients had been under dental supervision by the same dentist for more than one year, and were familiar with the procedure during checkups. This study showed a significant rise in systolic blood pressure (8.6 mmHg) and a tendency towards increased diastolic pressure (2.9 mmHg) during dental checkups in comparison with the values recorded 24 hours earlier during normal daily activity. These results were independent of the blood pressure classification (normotensive, borderline or hypertensive) of the patients and are comparable to the increases measured during a visit to the GP. Neither the sex nor the manner of the dentist had any significant influence on either the systolic or diastolic pressure values during the checkup. Nor did the phobic level of the patients significantly influence blood pressure values during the dental checkup. On the basis of the results of this study, it may be concluded that regardless of whether the patient is phobic or non-phobic, and regardless of the sex and manner of the dentist, blood pressure measurements taken during dental checkups are reliable and can be used for referral decisions.

Adolescent↗
PubMedDate not supplied

[Further comments on the so-called migraine personality].

In order to replicate previous findings, two studies were carried out comparing migraine patients and headache free controls in terms of degree of ambition, idea of tidiness, and rigidity. Migraineurs (75 Ss in study I, 82 in study II) were recruited in the frame of two large inquiries on headache frequency; control groups were made up of persons out of the same samples and matched for age, sex, educational level and professional status. Personality variables were assessed by means of a standardized questionnaire. Group differences did not attain statistical significance in any of the scales. Configural frequency analysis revealed that combination of increased ambition, idea of tidiness and rigidity, often considered as typical for persons with migraine, was actually more common among controls.

Adult↗
PubMedDate not supplied

Introduction: history and problems of compensatory adaptation of renal functions and of compensatory hypertrophy of the kidney.

The history of observations and experimental work on compensatory changes following the loss of renal mass, and the historical reasons for the distinction between the concepts of compensatory adaptation (of renal functions) and of compensatory hypertrophy (of nephrons) are outlined. While the effector mechanisms of both types of compensatory changes are being elucidated at a rapid pace, many questions concerning the primary changes initiating these events, the control mechanisms implied and the interrelationship between functional adaptation and hypertrophy remain unanswered.

Adaptation, Physiological↗
PubMedDate not supplied

[Development of gentamicin-resistant Small Colony Variants of S. aureus after implantation of gentamicin chains in osteomyelitis as a possible cause of recurrence].

AIM: Recently, S. aureus small colony variants (SCVs) were reported to persist within cultured endothelial cells and to cause persistent and antibiotic resistant infections in humans. Because gentamicin can very reproducably select for electron transport deficient SCVs as shown in earlier in vitro experiments, we searched for SCVs in a patient with chronic osteomyelitis, who received gentamicin beads. METHOD: Special culture and identification procedures for determination of SCVs were used, including testing of the S. aureus specific nuc gene, pulsed field gel electrophoresis (PFGE) as a typing method and characterization of the auxotrophism of the SCVs. RESULTS: In a case of a 34-year-old patient with chronic osteomyelitis who had previously been treated with gentamicin beads, menadione auxotrophic S. aureus SCVs as well as wild type S. aureus were recovered in multiple bone specimen. All different colony types isolated from simultaneous or from sequential specimen were shown to be clonal by PFGE. CONCLUSION: Recovery of S. aureus SCVs from a patient treated with gentamicin beads suggests that the slow release of gentamicin into the local environment may be an efficient way to select for and/or induce SCVs. These data should alert physicians to also consider SCVs when a treatment failure occurs in a patient that has received gentamicin beads.

Adult↗