Category: cancer prevention

Factor AF2 is an extract from the spleen and liver of sheep embryos and lambs. The product contains biotechnologically produced, chromatographically uniform, molecularly standardized polypeptides, glycopeptides, glycolipids and nucleotides, deproteinized and free of pyrogens’. Factor AF2 is intended mainly for use in ‘supportive antitumour therapy’, as a ‘biological antiemetic and analgesic’. The proposed duration of treatment is usually more than six months. The dosage varies considerably according to the indication. The average daily costs are, therefore, between DM 4.- (prevention of recurrence) and DM 107.- (adjuvant to chemotherapy). Allergic reactions have been reported in ‘rare cases’. Factor AF2 was developed in the forties by Guarnieri in Rome. Since 1984, Factor AF2 is ‘biotechnologically’ produced and as a ‘biological response modifier’ (BRM) in the oncotherapy distributed by Biosyn Arzneimittel GmbH, Stuttgart. Dr. rer. nat. T. Stiefel and Dr. rer. nat. H. Porcher are the representatives of Biosyn Arzneimittel GmbH. In the past, both worked with Vitorgan Arzneimittel GmbH (cytoplasmatic therapy according to Theurer). It is claimed that Factor AF2 contains ‘immunomodulating and immunorestorative biomolecules’ assignable to the BRM group. Terms and investigations from current immunological research are applied to Factor AF2. No preclinical investigations are available which demonstrate any cytostatic effect of Factor AF2. In vivo, no effects were observed on the transplanted meth-A-sarcoma in mice.(ABSTRACT TRUNCATED AT 250 WORDS)

[PubMed – indexed for MEDLINE]

Vitamin D physiology


Department of Endocrinology, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam, Netherlands.


Vitamin D3 is synthesized in the skin during summer under the influence of ultraviolet light of the sun, or it is obtained from food, especially fatty fish. After hydroxylation in the liver into 25-hydroxyvitamin D (25(OH)D) and kidney into 1,25-dihydroxyvitamin D (1,25(OH)2D), the active metabolite can enter the cell, bind to the vitamin D-receptor and subsequently to a responsive gene such as that of calcium binding protein. After transcription and translation the protein is formed, e.g. osteocalcin or calcium binding protein. The calcium binding protein mediates calcium absorption from the gut. The production of 1,25(OH)2D is stimulated by parathyroid hormone (PTH) and decreased by calcium. Risk factors for vitamin D deficiency are premature birth, skin pigmentation, low sunshine exposure, obesity, malabsorption and advanced age. Risk groups are immigrants and the elderly. Vitamin D status is dependent upon sunshine exposure but within Europe, serum 25(OH)D levels are higher in Northern than in Southern European countries. Severe vitamin D deficiency causes rickets or osteomalacia, where the new bone, the osteoid, is not mineralized. Less severe vitamin D deficiency causes an increase of serum PTH leading to bone resorption, osteoporosis and fractures. A negative relationship exists between serum 25(OH)D and serum PTH. The threshold of serum 25(OH)D, where serum PTH starts to rise is about 75nmol/l according to most surveys. Vitamin D supplementation to vitamin D-deficient elderly suppresses serum PTH, increases bone mineral density and may decrease fracture incidence especially in nursing home residents. The effects of 1,25(OH)2D and the vitamin D receptor have been investigated in patients with genetic defects of vitamin D metabolism and in knock-out mouse models. These experiments have demonstrated that for active calcium absorption, longitudinal bone growth and the activity of osteoblasts and osteoclasts both 1,25(OH)2D and the vitamin D receptor are essential. On the other side, bone mineralization can occur by high ambient calcium concentration, so by high doses of oral calcium or calcium infusion. The active metabolite 1,25(OH)2D has its effects through the vitamin D receptor leading to gene expression, e.g. the calcium binding protein or osteocalcin or through a plasma membrane receptor and second messengers such as cyclic AMP. The latter responses are very rapid and include the effects on the pancreas, vascular smooth muscle and monocytes. Muscle cells contain vitamin D receptor and several studies have demonstrated that serum 25(OH)D is related to physical performance. The active metabolite 1,25(OH)2D has an antiproliferative effect and downregulates inflammatory markers. Extrarenal synthesis of 1,25(OH)2D occurs under the influence of cytokines and is important for the paracrine regulation of cell differentiation and function. This may explain that vitamin D deficiency can play a role in the pathogenesis of auto-immune diseases such as multiple sclerosis and diabetes type 1, and cancer. In conclusion, the active metabolite 1,25(OH)2D has pleiotropic effects through the vitamin D receptor and vitamin D responsive elements of many genes and on the other side rapid non-genomic effects through a membrane receptor and second messengers. Active calcium absorption from the gut depends on adequate formation of 1,25(OH)2D and an intact vitamin D receptor. Bone mineralization mainly depends on ambient calcium concentration. Vitamin D metabolites may play a role in the prevention of auto-immune disease and cancer.

[PubMed – indexed for MEDLINE]