Regulation of melanin biosynthesis in the human epidermis by tetrahydrobiopterin.

The participation of (6R) 5,6,7,8-tetrahydrobiopterin (6-BH4) in regulating the tyrosine supply for melanin biosynthesis was investigated by the examination of human keratinocytes, melanocytes, and epidermal suction blisters from normal human skin and from patients with the depigmentation disorder vitiligo. Cells, as well as total epidermis, contained high phenylalanine hydroxylase activities and also displayed the capacity to synthesize and recycle 6-BH4, the essential cofactor for this enzyme. In vitiligo, 4a-hydroxy-BH4 dehydratase activity was extremely low or absent, yielding an accumulation of the nonenzymatic by-product 7-tetrahydrobiopterin (7-BH4) at concentrations up to 8 x 10(-6) M in the epidermis. This by-product is a potent competitive inhibitor in the phenylalanine hydroxylase reaction with an inhibition constant of 10(-6) M. Thus, 6-BH4 seems to control melanin biosynthesis in the human epidermis, whereas 7-BH4 may initiate depigmentation in patients with vitiligo.

Cloning, sequencing and functional studies of the gene encoding human GTP cyclohydrolase I.

We have identified a genomic clone containing the 5' regulatory region of the gene GTP-CH encoding human GTP cyclohydrolase I. The transcription start point (tsp) was mapped by 5'-rapid amplification of cDNA ends (5'-RACE). The 2.6-kb region upstream from the tsp showed promoter activity when ligated upstream from a reporter gene. The truncation of approximately 2 kb of the promoter did not change expression activity, while a further removal of 243 bp halved the activity. The promoter contains CCAAT and TATA boxes. The GC-rich region close to the tsp, which contains several putative Sp1-responsive elements, is required for maximum promoter activity. Interferon-gamma treatment of B-cells transfected with reporter constructs had no influence on the expression activity.

Intralymphatic interleukin 2 treatment in patients with acquired immunodeficiency syndrome: preliminary experience in three cases.

Patients with opportunistic infections during the course of acquired immunodeficiency syndrome (AIDS) were analyzed for cellular immune functions and found to be severely immunocompromised. In particular, interleukin 2 (IL 2) production appeared to be defect not only qualitatively but also quantitatively. In some of these patients, exogenous IL 2 improved immune response in vitro. Intralymphatically administered highly purified natural IL 2 was given repeatedly (over a time period of ten days) to three of these patients. In two cases, such a treatment course was repeated later. Clinical response - at least in some patients - appeared to be of temporary benefit. Shortly after termination of IL 2 application in two patients an increase of lectin responsiveness as well as improved reactivity in skin testing was noted, encouraging further exploration of IL 2 as an immunostimulatory drug in AIDS patients.

Biosynthesis of Erythrina alkaloids in Erythrina crista-galli.

A precursor application system was developed to allow the study of Erythrina alkaloid formation in Erythrina crista-galli. Fruit wall tissue of this species was recognized as the major site of alkaloid biosynthesis. The application of radioactively and 13C-labelled potential precursors showed that the hitherto assumed precursor (S)-norprotosinomenine was not incorporated into the Erythrina alkaloids. In contrast, (S)-coclaurine as well as (S)-norreticuline were metabolized to erythraline and erythrinine, respectively, suggesting that a coclaurine-norreticuline pathway is operative in Erythrina alkaloid formation. Feeding of [1-13C]-labelled (S)-norreticuline with subsequent NMR spectroscopy demonstrated that the resulting erythraline was exclusively labelled at position C-10. Therefore, the participation of a symmetrical intermediate of the diphenoquinone type in Erythrina alkaloid biosynthesis can be excluded.

[Gardner's syndrome. three patients with varying manifestations (author's transl)]. / Das Gardner-Sydrom--drei eigene Beobachtungen mit unterschiedlicher Organmanifestation.

Fully developed Gardner's syndrome is characterised by the triad of intestinal polyposis, osteomas and multiple soft tissue tumours. Absence of any one of these manifestations results in a bisymptomatic form. We describe three patients, one woman and two men aged 40, 46 and 51 years. In two patients the triad was fully expressed, but with varying organ involvement. The third patient was of the bisymptomatic type with osseous and intestinal lesions.

[Differential diagnosis of liver diseases in the nuclear spin tomogram]. / Differentialdiagnose von Lebererkrankungen im Kernspintomogramm.

In evaluating nuclear magnetic tomography for the diagnosis of liver disease, one must differentiate between circumscribed and diffuse lesions. Nuclear magnetic tomography provides additional information for lesions which are echogenic on ultrasound and can differentiate between metastases, haemangiomas and hamartomas. In diffuse parenchymal disease measurement of relaxation time can differentiate between fatty liver, cirrhosis (alcoholic, primary biliary), haemochromatosis (cirrhotic transformation) and hepatoma. NMR spectroscopy is a method for the future.

[Pancreaticorrhagia--imaging procedures compared]. / Hämosuccus pancreatis--bildgebende Verfahren im Vergleich.

Four patients with spontaneous bleeding from the pancreas are described. Transpapillary bleeding is diagnosed endoscopically. Angiography can demonstrate the eroded vessel directly. Ultrasound, CT and ERCP demonstrate the underlying abnormality in the pancreas. Bleeding into a cyst produces characteristic echoes, or an increase in density. NMR is able to demonstrate pancreatitis and pancreatic pseudo-cysts. Early diagnosis is extremely important, since without appropriate surgery, pancreatic bleeding is frequently fatal.

[Diagnosis of choledochal cysts. The methodological value of imaging procedures]. / Diagnostik der Choledochuszysten. Methodische Wertigkeit bildgebender Verfahren.

For 10 cases in which we detected cysts in the choledochus ourselves comparing traditional radiological methods (infusion-cholegram, ERC, scintigraphy, barium meal examination, angiography) with recent imaging procedures (ultrasound, CT, NMR) the following sequence of procedures proved to be favorable: Screening methods are ultrasound and infusion-cholegram. CT and NMR furnish good presentations of the intra- and extrahepatic dilatations of the bile duct. ERC still represents the best methods for demonstration of an extrahepatic cyst of the choledochus. Hepato-biliary functional scintigraphy is performed as a supplement. Barium meal examination and coeliacography furnish a small diagnostic contribution only.

New diagnostic and therapeutic possibilities in manifest idiopathic hemochromatosis.

Up until recently in clinical practice suspected hemochromatosis with a pathological iron-screening test (plasma iron, percentage transferrin saturation, serum ferritin, desferrioxamine-induced urinary iron excretion) made a liver biopsy necessary. Today, as a first step, the density of the liver parenchyma can be measured by means of computed tomography. Normal findings obviate the need for laparoscopy. Since the late forties weekly or twice weekly phlebotomy has been the sole form of treatment for manifest idiopathic hemochromatosis. In the mid-sixties the hopes placed in chelating substances (desferrioxamine) were not fulfilled, because the plasma half-life (only 7-10 minutes) of this drug was too short. Even with several daily injections only a small amount of iron was removed from the body tissue (10-25 mg daily urinary iron excretion). The introduction of portable infusion pumps in the late seventies offered us a new possibility of administering desferrioxamine by subcutaneous injection (Propper et al., 1976). Until that time such treatment was successfully used only in the field of pediatrics to treat secondary transfusion hemochromatosis in thalassemia. In one case of idiopathic hemochromatosis with severe organic involvement (right heart failure, repeated esophageal hemorrhage and bronzed diabetes) we had to achieve rapid iron elimination, and for this purpose we used continuous long-term desferrioxamine administration by means of a portable infusion pump (Autosyringe) in addition to phlebotomy. Since, particularly in the critical initial phase of treatment when heart failure was always threatening, great care had to be exercised in the use of phlebotomy, iron removal was achieved largely by desferrioxamine administration (daily up to 240 mg iron elimination in urine and stools).(ABSTRACT TRUNCATED AT 250 WORDS)

Disconnecting the yin and yang relation of epidermal growth factor receptor (EGFR)-mediated delivery: a fully synthetic, EGFR-targeted gene transfer system avoiding receptor activation.

The epidermal growth factor receptor (EGFR) is upregulated within a high percentage of solid tumors and hence is an attractive target for tumor-targeted therapies including gene therapy. The natural EGFR ligand epidermal growth factor (EGF) has been used for this purpose, despite the risk of mitogenic effects due to EGFR activation. We have developed a fully synthetic, EGFR-targeted gene delivery system based on PEGylated linear polyethylenimine (LPEI), allowing evaluation of different EGFR-binding peptides in terms of transfection efficiency and EGFR activation. Peptide sequences directly derived from the human EGF molecule enhanced transfection efficiency with concomitant EGFR activation. Only the EGFR-binding peptide GE11, which has been identified by phage display technique, showed specific enhancement of transfection on EGFR-overexpressing tumor cells including glioblastoma and hepatoma, but without EGFR activation. EGFR targeting led to high levels of cell association of fluorescently labeled polyplexes after only 30 min of incubation. EGF pretreatment of cells induced enhanced cellular internalization of all polyplex types tested, pointing at generally enhanced macropinocytosis. EGF polyplexes diminished cell surface expression of EGFR for up to 4 hr, whereas GE11 polyplexes did not. In a clinically relevant orthotopic prostate cancer model, intratumorally injected GE11 polyplexes were superior in inducing transgene expression when compared with untargeted polyplexes.