Biomedical subjects

T Günther

Publications and source records attributed to T Günther.

At least 55 records · Page 3Linked to original sources

PubMed1998

Multimodal imaging of residual function and compensatory resource allocation in cortical atrophy: a case study of parietal lobe function in a patient with Huntington's disease.

In a case of Huntington's disease (HD) with dementia and pronounced parieto-frontal atrophy, the functional state of the affected regions was investigated using functional magnetic resonance imaging (fMRI) and fluorodeoxyglucose-positron emission tomography (FDG-PET). It was observed that although parietal areas showed extensive atrophy and reduced resting glucose metabolism, the patient performed with similar accuracy but with longer response time in a visuospatial task compared with healthy control subjects. At the same time, the blood oxygen level-dependent (BOLD) fMRI signal in these areas, which are involved in visuospatial processing, showed a similar task-dependent modulation as in control subjects. The signal amplitude (signal percent change) of the task-dependent activation was even higher for the HD patient than in the control group. This residual functionality of parietal areas involved in visuospatial processing could account for the patient's performance in the task concerned, which contrasted with his poor performance in other cognitive tasks. The increased percent-signal change suggests that a higher neuronal effort was necessary to reach a similar degree of accuracy as in control subjects, fitting well with the longer reaction time. We propose that fMRI should be considered as a tool for the assessment of functionality of morphologically abnormal cortex and for the investigation of compensatory resource allocation in neurodegenerative disorders.

Adult↗

PubMed1998

Long-term results after repair of complete atrioventricular septal defects: analysis of risk factors.

BACKGROUND: We analyzed data from 320 patients to evaluate the impact of different preoperative, operative, and postoperative factors on the outcome after repair of complete atrioventricular septal defect. METHODS: Between October 1974 and December 1995, 320 patients with complete atrioventricular septal defect not associated with major cardiac anomalies were operated on. Two hundred seventy-four patients underwent total repair. Sixty-three patients (23%) were less than 6 months old. One hundred ninety-eight (72.2%) underwent primary repair. Seventy-six patients (27.7%) had a previous palliative operation. RESULTS: Operative mortality in patients who underwent primary repair decreased from 17.6% (1974 to 1979) to 5.0% (1990 to 1995) despite an increase in the number of patients younger than 6 months. In patients undergoing a two-stage procedure operative mortality was 3.9% (late mortality, 7.9%). Young age (<6 months) was an incremental risk factor (p = 0.008) for operative mortality in the early study period. Coarctation of the aorta (p = 0.02) and severe dysplastic left atrioventricular valve (p = 0.001) were associated with a higher risk for operative mortality. Freedom from reoperation at 10 years was 82.5% +/- 3.8%. CONCLUSIONS: In patients with complete atrioventricular septal defect, primary repair is the treatment of choice and can be accomplished with good results. In our experience over a period of more than 20 years, earlier date of operation, young age (<6 months), dysplastic left atrioventricular valve, and coexisting coarctation were incremental risk factors for hospital death. The presence of a previously placed pulmonary artery band did not alter the outcome of repair. The reconstructed atrioventricular valve shows a good and long-lasting performance.

Age Factors↗

PubMed1998

Somatic DNA alterations in breast carcinomas of different lymph-node status by DNA fingerprint analyses.

The purpose of this study was to screen for somatic changes in invasive breast tumors by multilocus DNA fingerprints comparing normal (blood) and malignant tissue samples from 34 patients. The comparison of lymph node-positive and node-negative breast carcinomas was of primary interest. After restriction enzyme digestion with HinfI and HaeIII, altered banding patterns were detected by using the oligonucleotide probe (GTG)5 in 7 of 34 (20.5%) and in 3 of 34 (8.8%) tumors after hybridization with (GACA)4. The overall frequency of changes thus amounted to 29.4%. Because long (GACA)n repeat motifs, generating predominant DNA fingerprint bands, are localized on the short arms of the human acrocentric chromosomes, sequences that are important in breast carcinogenesis may be present in these regions. The overall methylation status of the DNA does not appear to be responsible for DNA fingerprint differences, as can be demonstrated with the restriction endonuclease HaeIII. DNA fingerprint differences did not correlate with tumor grade, stage, and hormone receptor status. Tumors with lymph-node metastases expressed DNA fingerprint differences more frequently.

Aged↗

PubMed1998

The pS2 protein in colorectal carcinomas and metastases.

Expression of pS2 protein in 50 primary tumors, metastases and recurrent tumors of colorectal carcinomas has been analyzed by immunohistochemistry. Sixty percent of the primary tumors were at least focally positive for the antigen. There was no correlation between pS2 expression and histologic grade of the lesions. In contrast, pS2 expression in T4 and T3 tumors was significantly higher than in T2 carcinomas. Immunoreactions in carcinomas with distant metastases (MI) were stronger than in M0 cases. However, this difference did not reach statistical significance. The presence of lymph node metastases did not correlate with pS2 expression. High expression of pS2 in T4 and T3 carcinomas together with the finding of pronounced expression of the antigen at invasion fronts in single cases could be interpreted as a function in tumor cell invasion and motility. However, in metastases and recurrent tumors, pS2 expression did not differ from primary lesions (53% positive lesions). All in all, under consideration of the latter finding in particular and together with the randomly distributed immunopositive tumor cells and cell clusters in the majority of cases, it is more likely that the expression pattern of pS2 in colorectal carcinomas is a result of overall tumor cell heterogeneity.

Carcinoma↗

PubMed1998

Alterations of the p16/MTS1-tumor suppressor gene in gastric cancer.

Deletions, mutations and the functional inactivation of tumor suppressor gene p16 are involved in the genesis of different neoplasias. Little is known about the role of p16 gene alterations in the genesis of gastric carcinomas. This study aimed to detect genetic alterations of the p16 gene in gastric carcinomas. We analyzed p16 gene mutations and the frequency of loss of heterozygosity (LOH) at the p16 locus in 43 gastric carcinomas. PCR-SSCP analysis of exons 1 and 2 revealed only one gene mutation in a carcinoma of the diffuse type. Besides carcinomas of the diffuse, intestinal and the mixed type, we also investigated a small-cell primary gastric carcinoma, which was the only one to show a deletion in the p16 gene. LOH analysis was performed using two polymorphic markers located near the p16 gene (D9S171, D9S162) and a sequence-tagged-site marker (c5.1). Allelic loss was noted in two carcinomas of the diffuse type and in one carcinoma of the intestinal type. Allelic instabilities were found in one tumor of the intestinal type and diffuse type each. Although only five of 43 (11.6%) gastric carcinomas had p16 alterations, tumors of the diffuse type tend to show a higher number of genetic alterations near the p16 locus.

Adenocarcinoma↗

PubMed1998

Specific expression in mouse mesoderm- and neural crest-derived tissues of a human PDGFRA promoter/lacZ transgene.

The platelet-derived growth factor alpha-receptor (PDGFR-alpha) displays a lineage-specific expression pattern in the mouse embryo and is required for normal development of mesoderm and cephalic neural crest derivatives. The purpose of the present study was to demonstrate the in vivo promoter function of genomic DNA fragments representing the 5'-flanking part of the human PDGFRA gene. 2.2, 0.9 and 0.4 kb PDGFRA promoter fragments, ligated to a lacZ reporter gene, were microinjected into fertilized mouse eggs and transgenic mouse lines were established. The expression patterns were basically similar in the 2.2 and 0.9 kb lines and overlapped grossly the endogenous Pdgfra gene expression pattern. The transgenic line with the highest expression level was chosen for detailed analysis. Expression was, as expected, mainly confined to tissues of mesodermal and neural crest origin. No expression was found in epithelial tissues of endo- or ectodermal origin. The promoter fragments were also active in neuroepithelium and in certain neuronal cell types that did not faithfully express PDGFR-alpha mRNA, while they failed to specify reporter expression in PDGFR-alpha expressing O-2A progenitor cells and other glial elements of the central nervous system. Thus, the isolated human PDGFRA promoter contains most but not all of the regulatory elements that are necessary to establish tissue specific gene expression during development.

Animals↗

PubMed1998

Performance of a rapid whole blood test for Helicobacter pylori in primary care: a German multicenter study.

BACKGROUND: Serological rapid whole-blood tests for the detection of H. pylori are presently being promoted for use in primary care. We conducted a multi-center study to investigate the diagnostic accuracy of the Boehringer Mannheim Helicobacter pylori test (BM test), which is identical with the Cortecs Helisal test. PATIENTS AND METHODS: A previous diagnosis of H. pylori, a history of peptic ulcer diseases, or proton-pump inhibitor, bismuth or antibiotic use during the preceding month were exclusion criteria. The BM test was performed prior to endoscopy by 7 primary care physicians, 5 practicing gastroenterologists, or a single physician in the university hospital outpatient service. During endoscopy, antral and corpus biopsies were obtained for histology and rapid urease testing (RUT). H. pylori positivity was defined by histology and/or RUT as reference methods. H. pylori IgG-ELISA was performed additionally. RESULTS: Of the 203 patients included, 151 were H. pylori-positive by reference methods (74.4%). The overall accuracy of the BM test was 77.3%. Eight BM tests were indeterminate, and in the other 195 patients the test performed as follows: sensitivity 80.3%, specificity 81.3%, positive predictive value 92.9%, negative predictive value 57.4%. Using IgG-ELISA as reference, the BM test performance was similar. It also did not differ substantially among the three groups of physicians involved. CONCLUSIONS: We found the performance of the BM test to be insufficiently accurate, as both over- and underdiagnosis of H. pylori infection were not infrequent. This test needs to be improved before its use in primary care can be recommended.

Adolescent↗

PubMed1998

Differing patterns of Helicobacter pylori gastritis in patients with duodenal, prepyloric, and gastric ulcer disease.

BACKGROUND: We investigated the risk relationship between histotopographic patterns of Helicobacter pylori gastritis and peptic ulcer site. METHODS: Three hundred and eighty-three infected patients were classified as having duodenal ulcer (n = 79), prepyloric ulcer (n = 39), gastric (angular) ulcer (n = 28), and no ulcer (n = 237). Antral and corpus biopsy specimens were taken. Sydney system-based scores for bacterial density and activity and degree of gastritis were added to antral and corpus sum scores (SS) (range, 0-9). These were used to categorize the phenotype of gastritis. In addition, the presence or absence of mucosal atrophy was taken into account. The relative risk for ulcer association with these conditions was calculated. RESULTS: High-grade antral (SS > 5) associated with mild to moderate corpus (SS > 5) gastritis increased duodenal (RR = 4.9; confidence interval (CI), 2.8-8.5) and prepyloric ulcer risk (RR = 2.99; CI, 1.4-6.2). High-grade gastritis in the antrum (SS > 5) and corpus (SS > 5) increased gastric ulcer risk (RR = 3.7; CI, 1.6-8.3). Antral atrophy and/or intestinal metaplasia is associated with an increased gastric ulcer risk (RR = 3.3; CI, 1.4-7.8). CONCLUSION: The pattern of H. pylori gastritis may define a risk for peptic ulcer at various sites, but additional factors, not reflected in histology, also contribute to this risk.

Atrophy↗

PubMed1998

The prevalence of Helicobacter pylori gastritis in patients with reflux oesophagitis: a case-control study.

OBJECTIVES: To investigate the prevalence of Helicobacter pylori in patients with erosive oesophagitis in comparison with asymptomatic subjects. DESIGN: Hospital based case-control study. METHODS: Two hundred and nineteen consecutive patients with erosive oesophagitis diagnosed over 2 years were studied. Patients with secondary gastro-oesophageal reflux disease, prior H. pylori eradication therapy, PPI or antibiotics were excluded and two case groups were formed: (1) patients with oesophagitis alone (OEA), and (2) patients with oesophagitis and concomitant peptic ulcer disease (OE&PUD). H. pylori was assessed by antral and corpus mucosa histology and the rapid urease test. Age- and sex-matched controls, who underwent voluntary screening for H. pylori by the 13C-urea breath test, had neither symptoms nor a history of upper gastrointestinal disease. RESULTS: The 130 patients in the OEA group had a prevalence of H. pylori of 38.5% compared with 75.6% in the 41 patients in the OE&PUD group and 88.5% in a subgroup of the latter with duodenal ulcer (26 patients). Infected and non-infected cases showed no significant differences in terms of grade of oesophagitis and incidence of Barrett's oesophagus. The prevalence of H. pylori infection in OEA was similar to that found in matched controls. In OE&PUD the relative risk of H. pylori infection was 3.6-fold higher than in controls [P = 0.0069, 95% confidence interval (CI), 1.401-9.195]. CONCLUSION: The prevalence of H. pylori in oesophagitis without PUD is similar to that of the asymptomatic population with no history of upper gastrointestinal disease. When oesophagitis and PUD occur together, the infection rate is within the range found in PUD alone.

Adult↗

PubMed1998

Intestinal metaplasia at the gastro-oesophageal junction: Helicobacter pylori gastritis or gastro-oesophageal reflux disease?

BACKGROUND: Intestinal metaplasia, whether in the cardia or the distal oesophagus, has been uniformly defined as specialised columnar epithelium, suggesting a relation with Barrett's oesophagus. It is, however, not clear whether the risk factors associated with intestinal metaplasia are identical at both sites. AIMS: To investigate biopsy specimens obtained below the squamocolumnar junction (SCJ) in relation to endoscopic aspect, gastric histology, and clinical presentation. PATIENTS AND METHODS: In 423 patients investigated the endoscopic aspect of the SCJ was classified as unremarkable (group I, n = 315) or suggestive of Barrett's oesophagus (group II, n = 108). Standardised biopsy specimens from the antrum, corpus, and directly below the SCJ were investigated. RESULTS: Intestinal metaplasia was detected at the SCJ in 13.4% of group I patients, where it was significantly associated with gastric intestinal metaplasia (odds ratio (OR) 6.96; confidence interval (CI) 2.48 to 19.54) and H pylori (OR 7.85; CI 2.82 to 21.85), and in 34.3% of group II patients where it was significantly associated with reflux symptoms (OR 19.98; CI 6.12 to 65.19), erosive oesophagitis (OR 12.16; CI 3.86 to 38.24), and male sex (OR 6.25, CI 2.16 to 18.14), but not with H pylori or gastric intestinal metaplasia. CONCLUSION: This study suggests that the pathogenesis of intestinal metaplasia at the SCJ is not uniform: at an endoscopically unremarkable SCJ it is a sequela of H pylori gastritis, but coexisting with endoscopic features of Barrett's oesophagus it is associated with male sex and gastro-oesophageal reflux disease.

Barrett Esophagus↗

PubMed1998

Age and Helicobacter pylori decrease gastric mucosal surface hydrophobicity independently.

BACKGROUND: Gastric mucosal surface hydrophobicity (GMSH) is an essential component of the mucosal defence system that is decreased by Helicobacter pylori and non-steroidal anti-inflammatory drugs (NSAIDs). Gastric ulcers occur predominantly in elderly subjects, and may thus reflect diminished mucosal resistance. AIMS: To investigate whether aging decreases GMSH. PATIENTS: One hundred and twenty patients without peptic ulcer disease were divided into three age groups: I (41 years or below); II (41-64 years); and III (65 years or above). METHODS: Biopsy specimens were taken from the antrum, corpus, and cardia for histology (Sydney system), urease testing for H pylori, and for contact angle measurement of GMSH with a goniometer. The presence of specific H pylori antibodies was checked by immunoblotting. RESULTS: Fifty two patients (43%) were infected, and 68 were uninfected with H pylori. GMSH at all biopsy sites was lower in H pylori infected subjects (p=0.0001), but also decreased with age independently of infection status (p=0.0001). The most notable decrease in GMSH occurred between age groups I and II in those with, and between age groups II and III in those without, H pylori infection. GMSH was greater in antral than in corpus mucosa in both infected (p=0.0001) and uninfected patients (p=0.0003). CONCLUSIONS: A physiological decrease in GMSH with aging may contribute to the risk of ulcer development in the elderly, and may act synergistically with H pylori and/or NSAIDs on gastric mucosal defence.

Adult↗

PubMed1998

Expression of mdm2 and p53 in epithelial neoplasms of the colorectum.

AIMS: To evaluate the respective roles of mdm2 (murine double minute 2) and p53 in the development of colorectal carcinoma. METHODS: Formalin fixed, paraffin wax embedded tissues from 72 sporadic adenomas and 55 carcinomas were investigated by means of immunohistochemistry for mdm2 and p53. RESULTS: mdm2 was expressed weakly in 17 of 72 (23.6%) adenomas and in 14 of 55 (25.4%) carcinomas. p53 was expressed in 19 of 72 (26.4%) adenomas and in 23 of 55 (41.8%) carcinomas. Four adenomas and five carcinomas showed positive staining for both proteins. Overexpression of p53 in adenomas was associated with moderate and severe dysplasia but not with tumour size. No associations were found between the expression of mdm2 and either the degree of dysplasia or tumour size. In carcinomas, neither the expression of p53 nor mdm2 correlated with Dukes's stage, metastasis, or differentiation. No associations were found between the expression of p53 and mdm2 in either adenomas or carcinomas. CONCLUSIONS: Although mdm2 has been reported to be an oncogene, it does not appear to play a major role in the development of colorectal carcinoma.

Adenocarcinoma↗

PubMed1998

Pathobiochemical effects of graded magnesium deficiency in rats.

Severe Mg deficiency changed mineral homeostasis, induced membrane damage, increased lipid peroxidation and cytokine concentrations, and reduced immunocompetence. In order to investigate whether the pathobiochemical effects correlate directly with the degree of Mg deficiency or whether there might be a threshold with no detectable effects above, diets with 70, 110, 208, 330 and 850 ppm Mg were fed to growing Wistar rats. After feeding the diets for 0, 10, 20 and 30 days parameters of free radical action (malondialdehyde and vitamin E content), mineral content (Mg, Ca, Fe) in various tissues (liver, spleen, heart, kidney, muscle) and plasma parameters (Mg, Ca, Fe, alanine- and aspartate-aminotransferase) were measured. After 30 days 6-keto-prostaglandin F1 alpha, thromboxane B2, tumor necrosis factor-alpha, and immunoglobulins (IgG, IgM, IgA) were additionally analyzed. Tissue Mg content was either unchanged or only slightly reduced in severe Mg deficiency. Tissue Fe content rose when the extracellular Mg concentration was below 0.25 mM. There was a close positive correlation between tissue Fe and malondialdehyde content, and malondialdehyde was negatively correlated with vitamin E content. Below a threshold of about 0.25 mM plasma Mg concentration, transaminases increased in plasma. The same threshold could be observed for the increase of tissue Ca content, except in the kidney where calcifications were found already in mild Mg deficiency. Tumor necrosis factor-alpha and 6-keto-prostaglandin F1 alpha were increased when the plasma Mg concentration was below 0.15 mM, and thromboxane B2 was increased when plasma was lower than 0.25 mM. IgG and IgA were significantly reduced below 0.25 mM plasma Mg and IgM below 0.4 mM plasma Mg. Mild Mg deficiency, therefore, can be compensated and might not lead to pathological symptoms if not combined with other pathobiological conditions.

6-Ketoprostaglandin F1 alpha↗

PubMed1997

The expression of the mouse Zic1, Zic2, and Zic3 gene suggests an essential role for Zic genes in body pattern formation.

We examined the expression of Zic1, Zic2, and Zic3 genes in the mouse embryo by means of in situ hybridization. Zic genes were found as a group of genes coding for zinc finger proteins that are expressed in a restricted manner in the adult mouse cerebellum. We showed that the genes are the vertebrate homologues of Drosophila odd-paired, which may play an essential role in parasegmental subdivision and in visceral mesoderm development. The expression of the three Zic genes was first detected at gastrulation in a spatially restricted manner. At neurulation, the expression became restricted to the dorsal neural ectoderm and dorsal paraxial mesoderm. During organogenesis, the three genes were expressed in specific regions of several developing organs, including dorsal areas of the brain, spinal cord, paraxial mesenchyme, and epidermis, the marginal zone of the neural retina and distal regions of the developing limb. For all stages, significant differences in the spatial expression of Zic1, Zic2, and Zic3 were observed. Furthermore, the expression of Zic genes in Pax3, Wnt-1, and Wnt-3a mutant embryos suggested that Zic genes are not primarily regulated by the three genes which were expressed in dorsal areas similar to Zic genes. However, in open brain, a mutant with severe neural tube defects, and in the Wnt-3a mutant mice, the expression of Zic genes was changed. The changed expression pattern in Wnt-3a mutant mice suggests that Zic genes in the neural tube are regulated by the factors from notochord. Our findings suggest that Zic genes are involved in many developmental processes. Furthermore, analysis of gene expression patterns in different mouse mutants indicated that Zic genes may act upstream of many known developmental regulatory genes.

Animals↗

PubMed1997

p53 gene mutations and expression of p53 and mdm2 proteins in invasive breast carcinoma. A comparative analysis with clinico-pathological factors.

The aim of the study was to analyze p53 gene mutations and the expression of p53 and mdm2 proteins in 31 randomly selected invasive breast carcinomas. The results were then correlated with tumor grade, stage, estrogen receptor status, nodal status, and DNA ploidy. The expression of the proteins p53 and mdm2 was determined immunohistochemically using formalin-fixed, paraffin-embedded material. Screening for p53 mutation involved analysis of the highly conserved regions of the p53 gene (exons 5-9) by the polymerase chain reaction/ single-strand conformation polymorphism (PCR-SSCP) technique. PCR products with band shifts were directly sequenced. Immunohistochemical staining of p53 was positive in 9 cases (29.0%), only 2 of which showed a p53 gene mutation. These were identified as a C-->G transversion at the second position of codon 278 in exon 8 and an A-->G transition at the second position of codon 205 in exon 6. A third case with a mutation was observed (C-->T transition, position 1 of codon 250 in exon 7) that did not show p53 immunohistochemically. Of the 9 p53-positive tumors, 2 were moderately differentiated (grade II). The remaining tumors were poorly differentiated (7/9). By contrast, p53-negative carcinomas were well differentiated (grade I) in most cases (P = 0.02). DNA cytometry in 8 of the 9 p53-positive carcinomas revealed an aneuploid stem line. The majority of the p53-negative tumors were diploid (P = 0.01). Mdm2 oncoprotein was detected in 10 tumors (32.2%), 4 of which were p53-positive, including the 3 with mutations. The grading of the mdm2-positive tumors was moderate or poor, G1 carcinomas were always noted to be mdm2-negative (P = 0.04). Overexpression of p53 protein is a complex mechanism and does not merely indicate the detection of mutations in the p53 gene. This study has shown that p53 expression correlates with tumor grade and DNA ploidy. Mdm2 expression was also associated with the tumor grade. Immunohistological demonstration of the p53 protein alone is insufficient as a basis for comment on the functional state of the p53 gene and gene product. The interrelation between recognition of the p53 protein and gene mutation needs more careful assessment to define their roles in the control of neoplasia.

Adult↗

PubMed1997

In vitro evidence for a Donnan distribution of Mg2+ and Ca2+ by chondroitin sulphate in cartilage.

Fluoroquinolones are known for their ability to form chelate complexes with magnesium. Cartilage lesions observed in juvenile animals after quinolone treatment very probably are a consequence of the lack of functionally available magnesium. In cartilage, which contains high amounts of negatively charged proteoglycans, a Donnan distribution can be expected leading to an inhomogeneous distribution of ions (such as magnesium), which may support the toxic effects of magnesium deficiency or quinolone treatment of cartilage. We performed in vitro experiments using dialysis tubes to simulate the unequal distribution of proteoglycans in cartilage and measured the distribution of magnesium, calcium and ofloxacin. We found that the concentration of free magnesium is significantly reduced with the chondroitin sulphate-free solution due to a Donnan effect. For example, using a 3% chondroitin sulphate solution (outside the tubing) dialysed against a chondroitin sulphate-free solution (inside the tubing) the magnesium concentration decreased by 24% from 0.55 +/- 0.02 to 0.42 +/- 0.04 mmol/l inside the tubing during 48 h observation (P < 0.01). Under physiological conditions this unequal distribution of magnesium probably will be much more pronounced because chondroitin sulphate concentrations in cartilage are higher; nevertheless, magnesium concentration is sufficient for regular function of the tissue. During the sensitive phase of quinolone toxicity, magnesium in juvenile cartilage is lower than at other time points during postnatal development. Moreover, additional complexation by quinolones may further reduce the concentration of functionally available magnesium below the critical level.

Animals↗

PubMed1997

Quinolone-induced arthropathy: exposure of magnesium-deficient aged rats or immature rats, mineral concentrations in target tissues and pharmacokinetics.

Quinolone treatment or magnesium deficiency induce identical cartilage lesions in juvenile rats and show additive arthropathogenic effects. It has been shown previously that neither condition is arthropathogenic in 8-week-old rats. Joint cartilage from aged individuals is rather prone to pathological alterations but information on prolonged quinolone treatment and/or dietarily induced magnesium deficiency in aged animals is not available. We treated magnesium-deficient (n = 9) aged Wistar rats (age 15 months) and age-matched controls with daily doses of 600 mg ofloxacin/kg body wt. by gastric intubation for 28 days. Further groups of magnesium-deficient and control rats (n = 9 and n = 10, respectively) received the vehicle only. Peak plasma concentrations of ofloxacin in adult rats were 20.5 +/- 5.6 mg/l (mean +/- SD) following treatment with a single dose of 600 mg/kg body wt. At the end of the experiment the degree of magnesium deficiency was most pronounced in plasma (Mg2+-def., 0.33 +/- 0.12 mmol/l; control, 0.97 +/- 0.08 mmol/l) and less pronounced in sternal cartilage (Mg2+-def., 10.8 +/- 3.6 mmol/kg dry wt; control, 13.3 +/- 2.8 mmol/kg dry wt), whereas the magnesium concentration in femoral bone remained unchanged (Mg2+-def., 201 +/- 13 mmol/kg dry wt; control, 204 +/- 11 mmol/kg dry wt). Histological investigation of the knee joints revealed no cartilage lesions following ofloxacin treatment, magnesium deficiency or a combination of both conditions. By contrast, cartilage lesions such as scars and erosions of the joint surface, chondrocyte clusters within acellular areas of the cartilage matrix and persisting clefts were detectable in knee joints from 7 of 10 adult rats (age 9 months) which had been treated with 4 x 600 mg fleroxacin/kg body wt. at 5 weeks of age. Mean plasma concentration of fleroxacin in juvenile rats was approx. 50 mg/l between 1.5 and 6 h after dosing and the drug was still detectable in plasma 48 h after dosing (0.4 +/- 0.1 mg/l). Our data indicate that joint cartilage in aged rats is not altered by a 4-week quinolone treatment, even during magnesium deficiency. Cartilage lesions in adult rats were only detectable if the animals had been treated during the sensitive phase at 5 weeks postnatally.

Age Factors↗

PubMed1997

Effects of magnesium deficiency on magnesium and calcium content in bone and cartilage in developing rats in correlation to chondrotoxicity.

Quinolone-induced arthropathy has been described in juvenile rats between 3 and 6 weeks of age, but not in adult rats. The mechanism of this chondrotoxic effect is probably related to the Mg2+-chelating properties of the drugs, since identical cartilage lesions were observed in magnesium-deficient juvenile rats without quinolone treatment. However, the reasons for the phase-specificity of the effect are unknown. In the present study, we fed a magnesium-deficient diet to Wistar rats at different postnatal developmental stages. Cartilage lesions were only observed in magnesium-deficient rats between 3 and 5 weeks of age, but not in rats receiving the magnesium-deficient diet during weeks 5 to 8, weeks 8 to 11, or months 15 to 16. The formation of cartilage lesions was not related to the magnesium concentration in plasma, since magnesium concentrations in plasma were similarly reduced in rats with and without cartilage lesions. However, chondrotoxicity correlated with magnesium content in articular cartilage. In articular cartilage (articular and epiphyseal cartilage in immature rats) and bone, magnesium content was more reduced in rats receiving the magnesium-deficient diet between 3 and 5 weeks of age as compared with rats receiving the magnesium-deficient diet during weeks 8 to 11 postnatally. It was not possible to reduce the magnesium content in bone tissue of 15-month-old Wistar rats, which suggests a lower magnesium turnover in aged rats. Magnesium content in epiphyseal cartilage of 2-week-old rats (total femoral head) was 41.9 +/- 16.9 mmol/kg dry weight. The magnesium content in joint hyaline cartilage was significantly lower in 4-week-old rats (19.5 +/- 3.6 mmol/kg dry weight) and increased subsequently again to 48.5 +/- 9.2 mmol/kg dry weight (mean +/- SD; n = 8 to 16). Increase of the magnesium content in femoral bone between weeks 4 and 6 postnatally was less pronounced (139 +/- 10 and 175 +/- 15 mmol/kg dry weight, respectively). Taken together, these data show that in 4-week-old rats, magnesium concentration in joint hyaline cartilage is significantly lower than at other times during postnatal development. Only at this developmental stage can cartilage lesions be induced by feeding rats a magnesium-deficient diet. This period correlates well with the sensitive phase of immature rats toward the chondrotoxic action of quinolones.

Aging↗