Dopamine precursors and brain function in phenylalanine hydroxylase deficiency

Phenylalanine and tyrosine constitute the two initial steps in the biosynthesis of dopamine, which, in its turn, is the metabolic precursor of noradrenaline and adrenaline. The extracellular phenylalanine concentration influences brain function in phenylalanine deficiency (PHD) by decreased dopamine synthesis. It has been shown to induce EEG slowing, and prolonged the performance time on neuropsychological tests. The tyrosine concentration in the CNS is reduced in PHD, possibly implying insufficient substrate (= tyrosine) for catecholamine synthesis due to competition inhibition, for instance across the blood brain barrier. In experimental studies it has been shown that the synthesis and release of dopamine can be influenced by an increase in the availability of tyrosine. In PHD an extra dietary intake of three doses of tyrosine (160mg/kg/24h) induced a shortsning of reaction time and decreased variability, and in a double-blind crossover study a similar dose has been reported to induce an improvement on psychological tests. In a study with lower doses of tyrosine (110mg/kg/24h) no effect was found on reaction time tests. These findings need to be substantiated, and more detailed information should be obtained.     

Impulscytophotometrie der DNS in Hauttumoren

Zusammenfassung Die Impulscytophotometrie ermittelte bei 8 Hauttumoren einen höheren Anteil von Zellkernen mit erhöhtem DNS-Gehalt als bei Kontrollgeweben (Vollhaut, Lymphknoten und Zengenschleimhaut). Die DNS-Histogramme, welche jeweils 50000–200000 Zellkerne repräsentieren, korrespondierten in wesentlichen Einzelheiten den klinischen und histologischen Befund.Das neuartige Meßverfahren der Impulscytophotometrie erlaubt bei großer Genauigkeit jeder einzelnen Messung wegen der hohen Geschwindigkeit des Meßablaufs Untersuchungen an einer Vielzahl von Tumoren in kürzester Zeit.

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Pulse cytophotometry of DNA in skin tumours

Summary In eight samples of skin tumours a greater number of nuclei with an increased DNA content as compared to controls (normal skin, lymph nodes and periglottis) were found by pulse cytophotometry. DNA histograms—each histogram representing 50.000–200.000 nuclei—are predominantly in good correlation with the clinical and histological findings.With the new method of pulse cytophotometry it is possible to obatin DNA histograms of a great number of tumours in a short time with a high degree of accuracy.

     

Individual assessment of sperm morphology of single spermatozoa used for intracytoplasmic sperm injection

Intracytoplasmic sperm injection (ICSI) is an integral part of assisted reproduction. Although many papers have shown that global sperm count, sperm motility and sperm morphology of the ejaculate play no role in the fertilization rate after ICSI, embryologists who carry out ICSI, try to use the 'best looking' spermatozoa. The aim of the study was to investigate whether those spermatozoa with the best morphology really achieve the highest fertilization rate. In the present study, a total of 798 spermatozoa used for ICSI were documented by high-resolution photo. After ICSI the oocytes were cultured in single droplets and the formation of pronuclei was assessed 16 h later. The spermatozoa (all normal according to WHO criteria) were classified into four groups of different morphology. Group 1: normal head shape (approximately 5 microm diameter), group 2: like group 1, but with 15-20% smaller diameter, group 3: like group 1, but with 15-20% larger diameter, and group 4: like group 1, but with slight mid-piece cytoplasmic irregularities. Using the Pearson chi-square test, no significant difference in terms of fertilization was found among the different groups, showing that marginal sperm differences do not alter the fertilization process in ICSI.     

Intermittent administration of betalactam-antibiotics for treatment of severe infection in hemodialysis patients

Infections are a leading cause of morbidity and mortality in hemodialysis patients. Still, due to altered pharmacokinetics and potential toxic sideeffects, safe and efficient antibiotic therapy in dialysis patients remains a major challenge. We reviewed our experience with intermittent administration of betalactam antibiotics for treatment of severe infections in hemodialysis patients. A total of 81 episodes of infection in 45 patients was assessed. All patients were treated with betalactam antibiotics (cefepime in 11 episodes, cefpirom in 33 episodes, piperacillin in 9 episodes, amoxicillin in 18 episodes, ceftazidime in 10 episodes, respectively). All antibiotics were given post hemodialysis 3x per week. Treatment was considered efficient in case of a significant decrease in CRP in addition to clinical response. Overall treatment success rate was 85% (69 episodes of infection). The decrease of CRP was 52% (6.9 +/- 5.8 to 3.3 +/- 4.9 mg/dl; p = 0.00003). The mean duration of treatment was 19 +/- 13 days. Treatment was generally well tolerated. We conclude, that severe infections in hemodialysis patients can be treated safely and efficiently with an empiric therapy with betalactam antibiotics. Intermittent administration, potentially allowing ambulatory treatment, is possible.     

Placental defence is considered sufficient to control lipid peroxidation in pregnancy

Oxidative stress is characterized by an overweight of pro-oxidants against antioxidant forces and is associated with atherosclerosis, aging, and reproductive complications. Placenta is the major source of pro-oxidant agents, antioxidant enzyme-systems, and hormones and is able to keep the lipid peroxidation under control in normal pregnancy. As oxidation processes are increased in pregnancy, we would expect a shortening of lag phase of low density lipoprotein (LDL)-oxidation. LDL oxidation assessed by measuring conjugated diene formation is a marker for the early part of lipid peroxidation process and the balance of pro-oxidants and antioxidants influences length of lag phase. Our results show that resistance of LDL oxidation is unchanged during normal pregnancy in the second and third trimester. Only antioxidants are able to protect LDL. Estriol is an antioxidant, increases the lag-phase of LDL-oxidation in vitro, and its serum concentration raises enormous during late pregnancy. Thus the biological role of high levels of estriol during pregnancy may be part of the self-protection to limit oxidative damages.     

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