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Biomedical subjects

P Meisel

Publications and source records attributed to P Meisel.

At least 37 records · Page 2Linked to original sources
PubMed1991

Influence of albumin-bound bilirubin on the antibody-dependent cellular cytotoxicity of human cells in vitro.

In neonatal hyperbilirubinaemia the distribution of unconjugated bilirubin (BR) between albumin and cellular binding determines its toxicity. The relationship between the ratio of BR/albumin and the impairment of cellular functions was studied employing a system of antibody-dependent cellular cytotoxicity (ADCC) with erythrocytes as target cells. The cytotoxic activity of peripheral blood monocytes, lymphocytes and granulocytes is inhibited in a concentration-related manner depending on the molar ratio BR/albumin. The occupation of albumin binding sites by BR is related to the extent of inhibition of ADCC activity suggesting that there is a competition between albumin and cellular binding sites for free bilirubin. This competition is governed by the respective affinity and concentration of the binding sites. Bilirubin binding to the cellular (silent) membrane receptors leads to the chain of events resulting in impairment of cellular functions, i.e. ADCC.

Adult↗
PubMed1989

[Pathogenesis of bilirubin encephalopathy and subsequent therapeutic consequences].

At present the classic "kernicterus" has nearly disappeared, but toxic effects of bilirubin, nevertheless, play an important role in the etiology of late neurologic sequelae in VLBW infants. Even in very low concentrations of serum bilirubin CNS damages have to be expected when other metabolic disturbances induce the opening of blood-brain-barrier. Since safe criteria for predicting toxic effects of bilirubin do practically not exist, in VLBW infants with perinatal metabolic disorders early preventive phototherapy is indicated to keep the serum bilirubin level as low as possible. Experimental studies in animals showed brain protective effects of barbiturates apart from enzyme induction.

Blood-Brain Barrier↗
PubMed1988

Bilirubin binding and acid-base equilibrium in newborn infants with low birthweight.

Acidosis is known as a risk factor for the development of bilirubin encephalopathy in neonatal jaundice. However, few attempts have been made to evaluate the influence of acid-base state on bilirubin-albumin binding state in blood of newborn infants. Therefore, in 171 appropriate and 83 small for gestational age newborns (birthweight less than 2,500 g) the acid-base state in blood and bilirubin (BR) binding state in serum was measured at the ages of 3, 4, 5, and 8 days. There is a weak but significant correlation between standard base deficit and the ratio BR/reserve albumin as well as the toxic potential of serum BR. The results suggest that the higher risk in acidosis is not only caused by increased tissue binding of BR but also--at least partially--attributable to decreased BR binding in serum.

Acid-Base Equilibrium↗
PubMed1988

[Breast milk jaundice--a harmless symptom or a reason for stopping breast feeding?].

Increased interest in breast-feeding focuses attention on an undesirable side effect--the breast milk jaundice of the newborn. In this review a complication is given on contemporary knowledge with respect to types of breast milk jaundice, etiology, diagnostic and preventive strategies. Especially the early and late onset types of breast milk jaundice are distinguished. Though of the jaundice-aggravating effect of some human milks, there is no reason to avoid breast-feeding. Improved hospital nursing policies and careful information may help to encourage the mothers to continue in breast-feeding successfully.

Breast Feeding↗
PubMed1988

[Intrathoracic gastric duplication with intrapulmonary abscesses and perforation into the bronchial system--pathologico-anatomic peculiarities and diagnostic problems].

Gastric and enteric cysts represent genuine duplications. With regard to their genesis opinions are divided. These duplications may perforate into the lung parenchyma and/or the bronchial system, giving rise to specific symptoms. The only possible therapy is complete extirpation. The intrapulmonary metastases are drained and aspirated and can be cured without loss of lung tissue. A report is given on a thoracic cystic gastric duplication with haemorrhagic inflammation of the mucous membrane associated with erosions in a 8-week old boy. Clinically, the duplication was reflected by poor general health, dyspnea and tachypnea. The perforation into the bronchial system caused respiratory insufficiency. Using antibiotic therapy, immune substitution and surgery in combination, the boy was cured. The morphological findings, causative embryological factors, and diagnostic possibilities and problems are discussed.

Bronchi↗
PubMed1987

Transepithelial electric potential difference in newborns undergoing phototherapy.

When hyperbilirubinemic newborn babies underwent phototherapy, a significant decrease of the transepithelial electric potential difference of duodenal mucosa was observed, while the content of nonconjugated bilirubin and photobilirubins in the duodenal juice increased. This may indicate that the mucosa barrier function is damaged by bilirubin, with resulting increased sodium and water secretion into the gut. This phenomenon seems to be one of the reasons for diarrhea which is frequently observed in newborns undergoing phototherapy. Further investigations are necessary to understand the mechanism of bilirubin toxicity of the gut in detail.

Bile↗
PubMed1983

Albumin binding of photobilirubin II.

Photobilirubin II, a stereoisomer of bilirubin, binds to human serum albumin at a single binding site (K = 2.2 x 10(6)M-1), presumably the high-affinity bilirubin-binding site. Binding in the secondary (class II) binding sites is of minor importance. The results are discussed with respect to photometabolism of bilirubin and as a possible source of error in the determination of bilirubin unbound to albumin.

Bilirubin↗
PubMed1983

Bilirubin-induced cytomorphological changes in guinea-pig leucocytes.

The in vitro influence of bilirubin on guinea-pig peritoneal exudate cells was investigated at concentrations comparable to the conditions of neonatal hyperbilirubinaemia. In in vitro cultures of granulocytes and macrophages bilirubin manifested itself macroscopically by yellow colouring and microscopically by bilirubin aggregation near the nucleus. The intracellular bilirubin content was determined to be 40 nmol per 3 . 10(7) cells. The deposit of bilirubin was irreversible even after subsequent incubation with albumin. Subsequent incubation in heat-inactivated serum reverses binding of bilirubin to cells. Moreover, adding serum to the bilirubin sample prevents the influx of bilirubin. Simultaneously with the deposition of bilirubin there were conspicuous cytomorphological changes in the granulocytes and macrophages observed. The changes consist in a large number of rigid plasma extensions on the whole cell surface. The morphological changes were also reversible by subsequent incubation with serum and their formation was prevented by addition of serum. Since albumin as a well known bilirubin binding protein could not prevent the deposition of bilirubin or the morphological changes, it is suggested that serum factors can regulate the transport of bilirubin across cell membranes.

Animals↗
PubMed1982

Dependence of the efficiency of phototherapy on plasma bilirubin concentration.

407 newborns with idiopathic transitory hyperbilirubinaemia were examined with regard to the decrease in serum bilirubin levels during 24 hours of intermittent phototherapy (12 hours of light exposure). The photoeffect (i.e. decrease of serum bilirubin concentration after 24 hours of therapy) showed a unique and predictable nonlinear correlation with the plasma bilirubin concentration before treatment. This relationship can be used for individualizing the duration of phototherapy and the dose of light. The apparent effect of birth weight, gestational age, and postnatal age on the efficiency of phototreatment is only due to differing initial levels of bilirubin concentration. Intermittent illumination seemed to be more efficient than continuous.

Bilirubin↗