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Biomedical subjects

H Muller

Publications and source records attributed to H Muller.

At least 19 recordsLinked to original sources
PubMed2001

The AN2 protein is a novel marker for the Schwann cell lineage expressed by immature and nonmyelinating Schwann cells.

The expression of the 330 kDa AN2 glycoprotein was studied in the rodent peripheral nervous system. AN2 is expressed by immature Schwann cells in vitro and in vivo and downregulated as the cells upregulate myelin genes. A subpopulation of nonmyelinating Schwann cells in the adult sciatic nerve retains expression of AN2. In rat sciatic nerve crushes, where Schwann cell numbers increase after initial axonal loss and markers of immature Schwann cells show an upregulation, no increased expression of AN2 was observed. In contrast, AN2 expression was upregulated in nerves from peripheral myelin protein-22-transgenic rats, where immature Schwann cells expand without axonal loss. Furthermore, coculture with neurons upregulated AN2 expression on Schwann cells in vitro. Polyclonal antibodies against AN2 inhibited the migration of an immortalized Schwann cell clone in an in vitro migration assay, and the purified AN2 protein was shown to be neither inhibitory nor permissive for outgrowing dorsal root ganglion neurites. AN2 is thus a novel marker for the Schwann cell lineage. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of purified AN2 from early postnatal mouse brain demonstrated that AN2 is the murine homolog of the rat NG2 proteoglycan.

Animals↗
PubMed2001

Expression of putative anticancer targets in familial adenomatous polyposis and its association with the APC mutation status.

Several substances interfering with colorectal carcinogenesis may reduce or prevent adenoma formation in familial adenomatous polyposis (FAP), an inherited predisposition to colorectal cancer. This study determined the expression of genes coding for putative anticancer targets (COX-2, iNOS, MMP-7, ODC, PKCbeta, PPARgamma, RXRalpha, RXRbeta, RXRgamma) in FAP patients to provide one of the rationales for the design of chemotherapy and -prevention strategies. Gene expression was assessed by TaqMan analysis in colonic tissue of 9 FAP patients with mutations in the APC gene (APCpos), 5 FAP patients without identified genetic defect (APCneg), and 3 healthy individuals. Among the examined genes, PKCbeta and MMP-7 were most consistently altered in adenoma tissue relative to matched mucosa. Intriguingly, ODC was clearly overexpressed in polyps from APCpos but not APCneg patients. Furthermore, PKCbeta, MMP-7, ODC, and COX-2 as well as all RXRs displayed altered expression in apparently healthy FAP mucosa as opposed to that of healthy individuals. Our data suggests PKCbeta and MMP-7 to be the most suited as anticancer targets among the genes studied.

Adenomatous Polyposis Coli↗
PubMed1999

The cyclin B2 promoter depends on NF-Y, a trimer whose CCAAT-binding activity is cell-cycle regulated.

Cyclin B2 is a regulator of p34cdc2 kinase, involved in G2/M progression of the cell cycle, whose gene is strictly regulated at the transcriptional level in cycling cells. The mouse promoter was cloned and three conserved CCAAT boxes were found. In this study, we analysed the mechanisms leading to activation of the cyclin B2 CCAAT boxes: a combination of (i) genomic footprinting, (ii) transfections with single, double and triple mutants, (iii) EMSAs with nuclear extracts, antibodies and NF-Y recombinant proteins and (iv) transfections with an NF-YA dominant negative mutant established the positive role of the three CCAAT sequences and proved that NF-Y plays a crucial role in their activation. NF-Y, an ubiquitous trimer containing histone fold subunits, activates several other promoters regulated during the cell cycle. To analyse the levels of NF-Y subunits in the different phases of the cycle, we separated MEL cells by elutriation, obtaining fractions >80% pure. The mRNA and protein levels of the histone-fold containing NF-YB and NF-YC were invariant, whereas the NF-YA protein, but not its mRNA, was maximal in mid-S and decreased in G2/M. EMSA confirmed that the CCAAT-binding activity followed the amount of NF-YA, indicating that this subunit is limiting within the NF-Y complex, and suggesting that post-transcriptional mechanisms regulate NF-YA levels. Our results support a model whereby fine tuning of this activator is important for phase-specific transcription of CCAAT-containing promoters.

3T3 Cells↗
PubMed1999

Dynamic contrast-enhanced MRI of Implanted VX2 tumors in rabbit muscle: comparison of Gd-DTPA and NMS60.

We studied the dynamics of injected contrast enhancement in implanted VX2 tumors in rabbit thigh muscle. We compared two contrast agents Gd-DTPA and NMS60, a novel gadolinium containing trimer of molecular weight 2.1 kd. T1-weighted spin echo images were acquired preinjection and at 5-60 min after i.v. injection of 0.1 mmol/kg of agent. Dynamic T1-weighted SPGR images (1.9 s/image) were acquired during the bolus injection. Male NZW rabbits (n = 13) were implanted with approximately 2 x 10(6) VX2 tumor cells and grew tumors of 28+/-27 mL over 12 to 21 days. NMS60 showed significantly greater peak enhancement in muscle, tumor rim, and core compared to DTPA in both T1-weighted and SPGR images. NMS60 also showed delayed peak enhancement in the dynamic scans (compared to Gd-DTPA) and significantly reduced leakage rate constant into the extravascular space for tumor rim (K21 = 5.1 min(-1) vs. 11.5 min(-1) based on a 2 compartment kinetic model). The intermediate weight contrast agent NMS60 offers greater tumor enhancement than Gd-DTPA and may offer improved regional differentiation on the basis of vascular permeability in tumors.

Animals↗
PubMed1999

Blood pool and liver enhancement in CT with liposomal lodixanol: comparison with lohexol.

RATIONALE AND OBJECTIVES: The authors compared the time course and blood pool and hepatic enhancement of three different doses of liposomal iodixanol with those of iohexol. MATERIALS AND METHODS: A liposomal iodixanol formulation was prepared with 200 mg of iodine per milliliter total and 80 mg of iodine per milliliter encapsulated. Twelve normal New Zealand white rabbits divided into four groups received 75-, 100-, or 150-mg encapsulated iodine per kilogram doses of liposomal iodixanol or 2 mL/kg iohexol with 300 mg of iodine per milliliter. A liver section was scanned with serial computed tomography (CT) before the injection, immediately afterward, and at 1-minute intervals for 10 minutes. Region-of-interest measurements of the aorta and liver were plotted at each time point, and contrast enhancement was plotted as a function of time and iodine dose. RESULTS: All liposomal iodixanol doses produced greater liver enhancement than iohexol. Results were significant (P < .05) for 100 mg and 150 mg iodine per kilogram dose groups at time points beyond 2 minutes. Peak hepatic enhancement (change in attenuation) was 54.9 HU +/- 7.6 with iohexol, compared with 59.6 HU +/- 6.1, 73.3 HU +/- 3.6, and 104.1 HU +/- 8.8 for 75, 100, and 150 mg encapsulated iodine per kilogram doses, respectively. Hepatic enhancement increased rapidly after injection of liposomal iodixanol, plateauing 2-3 minutes later. Blood pool enhancement decreased rapidly. Steady-state liver enhancement with liposomal iodixanol increased linearly with dose. Aortic enhancement was greater with iohexol. CONCLUSION: Liposomal iodixanol yielded greater hepatic enhancement at lower total iodine doses than iohexol. Although liver enhancement occurred rapidly after injection, blood pool enhancement was brief.

Animals↗
PubMed1999

Interstitial MR and CT lymphography with Gd-dTPA-co-alpha, omega-diaminoPEG(1450) and Gd-dTPA-co-1,6-diaminohexane polymers: preliminary experience.

RATIONALE AND OBJECTIVES: The authors assessed the efficacy of two gadolinium-based polymers used as lymphotrophic contrast media for computed tomography (CT) and magnetic resonance (MR) imaging. MATERIALS AND METHODS: Two gadolinium-based polymers, gadolinium diethylenetriaminepentaacetic acid (DTPA)-co-1,6-diaminohexane (NC 22181) and Gd-DTPA-co-alpha, omega-diamino-polyethylene glycol(1450) (NC-66368), were formulated at a concentration of 80 mmol/L gadolinium. Doses of 0.1, 0.25, 1.0, or 2.0 mL per paw were administered subcutaneously into the hindpaws of normal rabbits. Spin-echo T1-weighted MR imaging (1.5 T) of rabbit popliteal and iliac nodes was performed before and immediately, 10 minutes, 2-3 hours, and 24 hours after injection. CT was performed 2-3 hours after injection of the high doses only. RESULTS: MR imaging revealed prompt enhancement of the popliteal nodes with both polymers at doses of 0.25 mL and above. For doses of 1.0 mL or less per paw, nodal percentage enhancement was maximal at 2 hours and then declined at 24 hours. At the highest doses, however, a reservoir of subcutaneous contrast material remained at the injection site and resulted in peak enhancement at 24 hours. At CT, popliteal node enhancement was faintly visible 2-3 hours after the administration of NC 22181. At lower doses, no enhancement was appreciable at CT. CONCLUSION: At 80 mmol/L formulations, the two gadolinium-based polymers provide excellent popliteal nodal enhancement on MR images. In addition, high doses of one polymer (NC 22181) were sufficiently concentrated in popliteal nodes to be visible on CT scans. Thus, this agent may be useful for both CT and MR lymphography.

Animals↗
PubMed1998

A female patient with the Rothmund-Thomson syndrome associated with anhidrosis and severe infections of the respiratory tract.

The Rothmund-Thomson syndrome is a rare syndrome which is believed to be inherited in an autosomal pattern. Poikiloderma of the face and extremities is a characteristic feature. Besides this, less common aspects have been reported like alopecia, cataracts, short stature, musculoskeletal/bone defects or small hands, hypogonadism, abnormal teeth, dysplastic nails, anhidrosis and a high incidence of cutaneous and non-cutaneous malignancies. We present a patient with the Rothmund-Thomson syndrome together with anhidrosis and multiple infections of the upper and lower respiratory tract. Investigation of immunological function revealed a low total number of T lymphocytes with a slightly depressed reactivity. Immunoglobulins were markedly increased.

Child↗
PubMed1998

[Dynamic surface tension of blood and synovial fluid in rheumatoid arthritis].

AIM: Assessment of the dynamic surface tension (DST) of blood serum (BS), synovial fluid (SF) in various courses of rheumatoid arthritis (RA). MATERIALS AND METHODS: Forty three patients with RA and 63 apparently healthy individuals were examined. DST of BS and SF was determined in the computer-aided tensiometer and some blood biochemical parameters were also measured. RESULTS: DST of BS in patients with RA were found to be higher than the normal values and some parameters c beta 2 and beta 3) of BS DST did not significantly differ from the normal values whereas others (beta 1 and gamma proved to be much lower. Depending on the disease course variants, there were some differences in these DST changes. There was a feedback between DST parameters and the levels of immunoglobulins, beta 2-microglobulin, and lipids in blood. CONCLUSION: Assessment of BS and SF DST may be useful in the differential diagnosis of RA, in the determination of its intensity and prognosis, and therapeutical efficiency.

Adolescent↗
PubMed1998

Linburg syndrome.

OBJECTIVE: To review the causes and demographics of Linburg syndrome. DESIGN: An illustrative case report and a demographic study. SETTING: Adult and pediatric orthopedic clinics at the Health Sciences Centre in Winnipeg. PATIENTS: One patient with Linburg syndrome and 200 patients and relatives presenting to adult and pediatric orthopedic clinics with conditions not involving their hands, wrists or forearms. OUTCOME MEASURES: The presence of the intertendinous anomaly and of carpal tunnel syndrome. RESULTS: Tendinous connection(s) between flexor pollicis longus and flexor digitorum profundus muscles were found in 20% of the study population. The anomaly was found in all age groups. No association was found between Linburg syndrome and the presence of carpal tunnel syndrome or previous injury to the hand or forearm. CONCLUSION: Tendinous connection between flexor pollicis longus and flexor digitorum profundus muscles is a common anomaly that rarely causes clinical symptoms.

Adult↗
PubMed1997

Involvement of a cyclic-AMP pathway in group I metabotropic glutamate receptor responses in neonatal rat cortex.

3,5-Dihydroxyphenylglycine (DHPG), (S)-3-hydroxyphenylglycine and (S)-4-carboxy-3-hydroxyphenylglycine (S-4C3HPG) stimulated phosphoinositide hydrolysis in neonatal rat cortical slices, but with lower maximal effect, in comparison with 2S,1'S,2'S-2-(2'-carboxycyclopropyl)glycine (L-CCG I) or (1S,3R)-1-aminocyclo-pentane-1,3-dicarboxylic acid (1S,3R-ACPD). DHPG, 1S,3R-ACPD, and S-4C3HPG also evoked a rapidly desensitizing increase in [Ca2+]i in cortical layers of neonatal brain slices. (R,S)-alpha-methyl-4-tetrazolyl-phenylglycine (MTPG), and (R,S)-alpha-methyl-4-phosphono-phenylglycine (MPPG) inhibited the increase of phosphoinositide hydrolysis elicited by 1S,3R-ACPD but not that by R,S-DHPG. In contrast, the selective group II receptor agonist (1S,2S,5R,6S)-2-amino-bicyclo-[3.1.0]-hexane-2,6-dicarboxylate (LY 354740) potentiated the response of R,S-DHPG. Finally, 8-(4-chlorophenylthio)-cAMP, a membrane permeant analogue of cAMP, reversed the stimulatory effect of 1S,3R-ACPD and S-4C3HPG on phosphoinositide hydrolysis and [Ca2+]i mobilization, without affecting the response induced by R,S-DHPG. These data suggest that, in neonatal rat cortex, the activation of group II metabotropic glutamate receptors potentiates the phosphoinositide hydrolysis and [Ca2+]i responses mediated by group I metabotropic glutamate receptors.

Animals↗
PubMed1997

Cloning and characterization of actin depolymerizing factor from Toxoplasma gondii.

We determined the predicted amino acid sequence of actin depolymerizing factor (ADF) from Toxoplasma gondii by sequencing the full-length cDNA. T. gondii ADF consists of 118 amino acids (calculated molecular weight 13,400) and shares a high degree of sequence similarity to other low molecular weight actin monomer sequestering proteins, especially Acanthamoeba actophorin, plant ADFs and yeast and vertebrate cofilin. ADF from T. gondii is smaller and does not contain a nuclear localization sequence like the related vertebrate proteins. Southern blot analysis indicates that T. gondii ADF is a single-copy gene. Homogeneous recombinant T. gondii ADF purified from E. coli is active in binding actin monomers and depolymerizing F-actin. Localization of ADF by immunofluorescence and immunoelectron microscopy indicates ADF is scattered throughout the cytoplasm and prominently localized beneath the plasma membrane in T. gondii.

Actin Depolymerizing Factors↗
PubMed1997

The transfer of 137Cs from barley to beer.

Beer has been brewed from barley contaminated with 137Cs as a consequence of the Chernobyl accident. The 137Cs activity has been measured in all intermediate steps and in the by-products of the production process. About 35% of the 137Cs in barley were recovered in beer. Processing factors defined as the concentration ratio of processed and raw products were determined to be 0.61, 3.3, 0.1 and 0.11 for malt, malt germs, spent grains and beer, respectively.

Beer↗
PubMed1993

Xeroderma pigmentosum-Cockayne syndrome complex in two patients: absence of skin tumors despite severe deficiency of DNA excision repair.

Two brothers had a complex combination of two DNA repair disorders: Cockayne syndrome and xeroderma pigmentosum. This rare combination has previously been observed in only two other patients. The clinical signs shared by these two brothers and the two other previously described patients include severe sun sensitivity, freckling, diminished stature, hearing and movement impairment, and neurologic degeneration. Although defective UV-induced unscheduled DNA synthesis has been demonstrated (5% of normal), no skin cancers have appeared in these 38- and 41-year-old brothers, whereas skin cancers developed at a relatively early age in the two previously described patients who also had defective UV-induced unscheduled DNA synthesis.

Adult↗
PubMed1991

Induction of fracture healing using fibrous calcium phosphate composite spherulites.

The healing of large fractural defects is a difficult clinical problem, especially if it occurs in elderly or otherwise debilitated patients. The objective of this study is to determine if a new formulation of fibrous calcium phosphate crystals would induce fracture healing in vivo. Fibrous calcium phosphate (FCP) can be grown with unique size, shape, and surface area characteristics as a resorbable or nonresorbable, osteoconductive or osteoinductive material. In comparison with other conventional calcium phosphate particulates, FCP particles possess approximately x 100 to x 1000 more surface area. One-and-one-half centimeter sections were removed from the ulnas of 12 rabbits. Three groups had fibrous calcium phosphate spherulites (4-8 microns, 150-300 microns, 400-600 microns) mixed with collagen and a growth factor-bonding agent injected into the ulnar defect. One site per group was not treated. X-rays were obtained during the study and the percentage of the ulna defect filled in by callous was measured. The percentage was recorded as the amount of fracture healing for each site. Histologic examination of the ulnas was performed following sacrifice at 12 weeks. Fracture sites treated with fibrous calcium phosphate showed significantly greater healing (0.79 +/- 0.3) than control animals (0.36 +/- 0.1) (P less than .05, unpaired t-test) radiographically. Histologic examination showed that the spherulites remain in situ and become embedded within the new growth of fibrous tissue, collagen and new bone. Radiographically and histologically, FCP preparations appear to accelerate fracture healing by inducing new bone formation, into which they often become embedded.

Animals↗
PubMed1990

[The population explosion in Algeria: the causes, the effects, and the solutions].

"For decades Algeria has had one of the highest population growth rates in the world, arising directly from a steady gap between deathrates and birthrates. The reasons are of a complex social, economic and cultural kind, such as high infant mortality, traditionally early marriage, family models largely determined by religion, the common practice of child labour and other factors. As a consequence of the mismatch between economic and demographic growth the society is confronted by growing mass unemployment, underemployment, food supply problems, housing shortages and ecological crises. The critical economic situation in the eighties reduced the prospects for constraining the population explosion by quickly conquering socioeconomic underdevelopment. Nowadays Algeria is deliberately following a programme for family planning, which is also supported to a certain extent by the Islamic clergy." (SUMMARY IN ENG)

Africa↗