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Biomedical subjects

B Müller

Publications and source records attributed to B Müller.

At least 577 records · Page 32Linked to original sources
PubMed1967

The immune response to a hybrid protein molecule; specificity of secondary stimulation and of tolerance induction.

Upon immunization with LDH-III (subunit composition AABB) rabbits produce anti-A and anti-B antibodies in comparable amounts. These antibodies fit equally well to the hybrid enzyme and to LDH-V (AAAA) or LDH-I (BBBB) respectively, as tested by passive hemagglutination inhibition. No antibodies reacting with both LDH-I and LDH-V were detected. A minority of hybrid-specific antibodies was, however, present in the sera. Animals primed with LDH-III respond regularly to a boosting injection of LDH-V with the production of large amounts of anti-A (but not anti-B) antibodies. A similar injection of LDH-I stimulates (if it has any effect at all) the production of anti-B antibodies only. Stimulation with one of the pure types does not impair a subsequent response to the other. The majority of the animals primed with LDH-III responded not at all or weakly to a boosting injection of LDH-I, though antibodies to LDH-I were present in the sera at the time of stimulation. This effect can hardly be explained on the basis of serological sepcificity. Hyporesponsiveness to LDH-III can be induced by injection of LDH-V into the newborn. Both anti-A and anti-B titers are equally depressed. Within the dose range tested, LDH-I does not exert any tolerogenic action with respect to LDH-III. The carrier property of subunit A is evident in the induction of both immunity and tolerance to LDH-III. The early phase of the immune response to the hybrid enzyme may be carrier-specific, and receptors for the haptenic subunit B may not exist at that stage.

Animals↗
PubMedDate not supplied

cDNA cloning of the constant region genes of the guinea pig alpha/beta T-cell receptor.

A lambda gt11 cDNA library was prepared from activated guinea pig T-lymphocyte blasts. cDNA clones coding for the alpha-chain and beta-chain of the constant region of the guinea pig T-cell receptor were isolated by means of crosshybridization using the corresponding mouse cDNA genes. The guinea pig and the corresponding mouse cDNA genes hybridized in Northern blots with mouse mRNA of the same size. Guinea pig T-cell receptor mRNA showed the same size like its mouse counterpart. In contrast to the alpha-chain clone, genomic Southern blot analysis showed that the identified beta-chain gene fragment undergoes genomic rearrangement during T-cell differentiation.

Animals↗
PubMedDate not supplied

Reduced body fat in long-term followed-up female patients with anorexia nervosa.

We aimed to evaluate both body composition and serum leptin levels in females with a past history of anorexia nervosa (AN) adjusted for their current body mass index (BMI). Twenty-three females with a past history of AN were followed-up 10 years after inpatient treatment and compared to 23 female controls of a similar age range matched for BMI on a one to one basis. Serum leptin levels were assessed and percent body fat (%BF) was determined via bioelectric impedance analysis. Differences of both %BF and leptin levels between cases and controls were tested under the hypothesis that cases have lower %BF and lower serum leptin levels than the controls. %BF was indeed lower in the cases compared to the controls (p < 0.05). However, differences in leptin levels between both groups just failed significance (p = 0.051). We conclude that body composition differs between long-term followed-up patients with AN and BMI- and gender-matched controls. Based on the finding that the former patients reported being more physically active, we assume that the higher physical activity levels in recovered patients with AN underlie the lower %BF.

Adipose Tissue↗
PubMedDate not supplied

Analysis of flame retarded polymers and recycling materials.

Recycling activities on polymeric materials are increasing and becoming more and more important in recent years. For polymers containing no flame retardants, suitable recycling strategies already exist. In order to investigate the recyclability of flame retarded polymers that contain brominated flame retardants, a number of samples were analysed as received from a recycling company. Following the identification and sorting of the samples according to type of polymers and flame retardants, material recycling was tested for the flame retarded polymers identified to occur most frequently. The reactivity of the flame retardants during the recycling procedure was studied by analysing for brominated dioxins and furans. The results demonstrate that flame retarded polymers can be recycled under certain experimental conditions.

Bromine↗
PubMedDate not supplied

[Cruciate ligament injuries with knee joint effusion--why can the Lachman sign not be elicited?].

In acute anterior cruciate ligament (ACL) lesions with effusion of the knee joint it is often difficult to realize a positive Lachman sign. It was suggested that the tension of the joint capsule may reduce tibial displacement although the ACL is completely disrupted. In 10 cadaver knee joints the ACL was dissected and the capsule was closed again. By a canula the knee joints were filled with isotonic saline solution in steps of 20 ml up to 100 ml. Before and after dissection of the ACL and during filling the joint we measured the anterior tibial displacement by use of the MEDmetric KT 1000 arthrometer. In a second series we examined 5 patients with acute effusion of the knee joint before and after puncture of the effusion. We detected the electromyographic activity of the quadriceps muscle end and the hamstrings during the KT 1000 test and patellar reflex. In the cadaver tests we found no reduction of the anterior tibial translation while filling the joint with saline solution. The electromyographic examinations showed a reflectory action in the quadriceps muscle and in the hamstrings when the Lachman test was performed. In the quadriceps muscle the electromyographic amplitude was reduced after puncture; the hamstrings showed a drastically reduced amplitude and duration of the signal. When patellar reflex was performed we recorded an electromyographic action in both muscle groups, too. Puncture could only reduce the signals of the hamstrings. Our results suggest that the reduction of the anterior drawer and the Lachman test in acute effusion is caused not mechanically by the tension of the capsule but by a reflectory muscle action of the hamstrings.

Anterior Cruciate Ligament↗
PubMedDate not supplied

[Proprioceptive deficit following cruciate lesions--afferent disorder or compensatory mechanism?].

It was suggested that the ACL has not only mechanical functions but also acts as proprioceptive organ. In cruciate deficient knees pathological patterns of muscle control were found. These findings could be caused by a disturbed afferent signal from the disrupted ACL or by secondary changes in muscle innervation, which shall protect the instable knee against subluxation. 33 patients with unilateral operative ACL repair (21 cases with primary suture, 12 cases with autogenous ligamentum-patellae-reconstruction; average post op 36.5 yr) were examined clinically and with the KT 1000 arthrometer (MEDMETRIC Inc.). Patients history was evaluated by using the LYSHOLM score. During a cycling task the electromyographic activity was monitored from the thigh muscles (M. vastus lat. and med., lat. and med. hamstrings). In comparison to the ACL deficient patients, we tested 25 healthy subjects of same age and activity level. In the ACL group the following differences to the normals were found: the M. vastus lat. showed a significantly delayed onset, earlier end and shorter duration. M. vastus med. had the same pattern; the delayed begin of activity and the shorter duration were statistically significant. M. biceps femoris showed a significant later onset and shorter duration. So did the medial hamstrings; the differences, however, were not statistically significant. There was no significant difference between operated and healthy leg in the ACL group. By comparing the primary sutures and the ligamentum-patellae-reconstructions no significant differences were found. The instable patients (KT 1000 > 3 mm) of the ACL group showed more distinct differences in the EMG pattern than the patients with stable knee joints.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

An acidic microenvironment inhibits antitumoral non-major histocompatibility complex-restricted cytotoxicity: implications for cancer immunotherapy.

Local immunosuppression may explain the failure of an effective immune response against solid tumors. Although it is well known that the interstitial pH is significantly lower in solid tumors than in normal tissue, only a few studies in the mouse system have investigated the influence of this acidic milieu on the anti-tumoral cytotoxic response. Here the authors report the suppression of human non-major histocompatibility complex (MHC)-restricted cytotoxicity against tumor cells by an acidic extracellular pH (pHe). Unstimulated peripheral blood mononuclear cells, lymphokine-activated killer (LAK) cells, and natural killer cell clones were used as effector cells. According to pH measurements in solid tumors, representative pH values of 7.2 to 5.3 were chosen during the cytotoxic assays. Target cell lysis was measured using two nonradioactive fluorometric methods, namely two-color flow cytometry and a modified calcein-release assay, which allowed cell-mediated cytotoxicity to be measured and compared with that in adherent targets. Using K562, Daudi, or Raji as suspended target cell lines, the cytotoxic activity of unstimulated peripheral blood mononuclear cells and of LAK cells was markedly reduced by a decreasing pHe. An extracellular pH of 5.8 to 5.3 resulted in a nearly complete loss of the cytotoxic response. This pHe-dependent impairment of the killing activity could also be shown for killer cells stimulated with interleukins-7 and -12, phytohemagglutinin, or lipopolysaccharide. The lytic potential of homogeneous natural killer cell clones as effectors was also strictly influenced by the surrounding pH. The pHe dependence of the non-MHC-restricted killer cell functions against tumor cells seems to be a general phenomenon, because the cytolytic activity of LAK cells against six human adherent tumor cell lines (HeLa, HepG2, LS174T, LS174Te, MCF-7, and RT112) was also clearly reduced under acidic conditions. To initiate the killing process, adhesion molecules play an important role in recognition and binding of the target cell. However, flow cytometric analysis revealed that the expression pattern of relevant adhesion molecules was unaffected by acidic pHe. In conclusion, these data clearly indicate an inhibition of non-MHC-restricted cytotoxicity against tumor cells by an acidic pHe, which may contribute to the failure of immunosurveillance against solid tumors. Consequently, efforts to enhance the anti-tumoral cytotoxicity by immunotherapies may have limited success.

Acids↗