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Biomedical subjects

C Fritsch

Publications and source records attributed to C Fritsch.

85 records · Page 5Linked to original sources
PubMed1979

Formation of ribosome-RNA initiation complexes with alfalfa mosaic virus RNA 4 and RNA 3.

RNA 4 of alfalfa mosaic virus (AMV) is a monocistronic messenger for the coat protein. We have determined the sequence of the 40 +/- 2 nucleotides in RNA 4 that were protected in the initiation complex formed with wheat germ 80 S ribosomes from digestion by T1 or pancreatic ribonucleases. The AUG coat protein initiation codon was near the middle of this protected region. We have found two ribosome-binding sites in RNA 3. The principal one, near the 5' end, is the initiation site for the major translation product, a 35,000 dalton protein. The second site binds ribosomes only weakly, at the beginning of the "silent" coat protein cistron, and is similar but not identical to the initiation site protection site is discussed.

Base Sequence↗
PubMed1978

Evidence for the existence of a coat protein messenger RNA associated with the top component of each of three tymoviruses.

On centrifugation in a CsCl density gradient the three tymoviruses, eggplant mosaic, wild cucumber mosaic, and okra mosaic, separate into a major bottom component and several less dense minor components. The RNA of the top component is composed of about 90% tRNA and 10% of an approximately 250 000 dalton messenger RNA. The latter induced the synthesis of coat protein when translated in wheat-germ and rabbit-reticulocyte cell-free systems.

Animals↗
PubMed1976

Physical and functional heterogeneity in TYMV RNA: evidence for the existence of an independent messenger coding for coat protein.

Turnip yellow mosaic virus RNA can be separated into two distinct components of 2 times 10(6) and 300 000 daltons molecular weight after moderate heat treatment in the presence of SDS or EDTA. The two species cannot have arisen by accidental in vitro degradation of a larger RNA, as they both possess capped 5' ends. Analysis of the newly synthesized proteins resulting from translation of each RNA by a wheat germ extract shows that the 300 000 molecular weight RNA can be translated very efficiently into coat protein. When translated in vitro the longer RNA gave a series of high molecular weight polypeptides but only very small amounts of a polypeptide having about the same mass as the coat protein. Thus our results suggest that the small RNA is the functional messenger for coat protein synthesis in infected cells.

Genetic Code↗
PubMedDate not supplied

Successful surgery of multiple recurrent basal cell carcinomas guided by photodynamic diagnosis.

We describe a 56-year-old Caucasian man with history of multiple regressed basal cell carcinomas. During the last 20 years approximately 200 histologically proven basal cell carcinomas preferentially localized on the face were surgically treated. Several large skin grafts were necessary to cover the extensive tissue defects on the face and scalp. Although all excised tissues were histologically proven to be basal cell carcinomas with tumor-free margins, new tumors developed in proximity to the skin graft margins. The dissemination of the new tumors made it difficult to perform additional invasive operation procedures without influencing the cosmetic result. Thus, we used photodynamic diagnosis to improve detection and demarcation of the neoplastic tissues. This procedure facilitated surgical planning and enabled primary in toto excisions. Surgical trauma and a number of interventions were thus minimized with the consequence of improved cosmetic and functional results.

Aminolevulinic Acid↗
PubMedDate not supplied

Green light is effective and less painful than red light in photodynamic therapy of facial solar keratoses.

Photodynamic therapy (PDT) with topically applied delta-aminolevulinic acid (ALA) is increasingly employed to treat patients with multiple solar keratoses and superficial skin tumors. For these indications, ALA-PDT has been shown to be highly efficient. Treatment of multiple or extended lesions, however, is substantially hampered by the fact that ALA-PDT is associated with burning pain during the irradiation procedure. The standard irradiation devices commonly used for ALA-PDT emit red light around 630 nm. In the present half-side comparison study we have observed that ALA-PDT employing a green light irradiation device (543-548 nm) is equally effective, as compared with standard red light ALA-PDT. In contrast to red light ALA-PDT, however, green light ALA-PDT caused only little tingling and burning but no pain. These observations indicate that green light ALA-PDT is superior to standard ALA-PDT, because it is associated with less unwanted side effects.

Aged↗
PubMedDate not supplied

Porphyria cutanea tarda.

Porphyria cutanea tarda (PCT) is the most frequent form of porphyria. The underlying enzymatic defect in PCT is a reduced activity of the enzyme uroporphyrinogen decarboxylase (Uro-D). Four different types of Uro-D disturbances are known. Pseudoporphyrias such as porphyria cutanea uraemica or drug-induced PCT-like skin symptoms are distinguished from PCT. Porphyrinogens such as estrogens or alcohol, or other inducers of P450 isoenzymes provoke PCT. Polymorphisms of P450 isoenzymes, iron overload and infection with hepatitis C virus play an important role in the etiopathogenesis of disease manifestation. Dominant clinical symptoms are bullae, increased cutaneous vulnerability, hypertrichosis and elastosis. Biochemically, total porphyrin levels in urine are increased with a predominance of uroporphyrin and heptacarboxylic porphyrin. Isocoproporphyrin is demonstrable in feces. Best therapeutic strategies are the oral administration of chloroquine 125 mg twice a week and repetitive bloodlettings or the combination of both.

Coproporphyrins↗
PubMedDate not supplied

Congenital erythropoietic porphyria.

Congenital erythropoietic porphyria (CEP) is one of the rarest autosomal-recessive disorders of the porphyrin metabolism caused by the homozygous defect of uroporphyrinogen III cosynthase. High amounts of uroporphyrin I accumulate in all cells and tissues, reflected by an increased erythrocyte porphyrin concentration and excretion of high porphyrin amounts in urine and feces. Dermal deposits of uroporphyrin frequently induce a dramatic phototoxic oxygen-dependent skin damage with extensive ulcerations and mutilations. Splenomegaly and hemolytic anemia are typical internal symptoms. Skeletal changes such as osteolysis and calcifications are frequent. Up to date 130 cases of CEP have been published. Splenectomy and erythrocyte transfusions showed some beneficial effect. Bone marrow transplantation was performed in 3 patients and stem cell transplantation in 1. The best therapy is the avoidance of sunlight. We give a report on our latest cases of CEP.

Adolescent↗
PubMedDate not supplied

Photodynamic diagnosis and therapy in dermatology.

The topical application of delta-aminolevulinic acid (ALA) induces porphyrin formation in the skin, preferentially in tumor tissues. Irradiation of the porphyrin-enriched tumor tissue with Wood's light leads to emission of a brick-red fluorescence. This principle may be used as a diagnostic procedure which may be termed photodynamic diagnosis (PDD). In ALA-PDD, tumors and precancerous lesions of the skin reveal a homogeneous, intensive red fluorescence. Psoriatic lesions also show a strong but inhomogeneous porphyrin fluorescence. ALA-induced porphyrin fluorescence in preoperative planning is a valuable method to determine the peripheral borders of a given tumor. The histopathological extensions of the tumors correlate well with the borders detected by the tumor-specific fluorescence. The main indications of PDD are the delineation of clinically ill-defined skin tumors and the control of the efficacy of other tumor therapies. Photodynamic therapy (PDT) utilizes exogenously applied or endogenously formed photosensitizers and their activation by light to induce cell death via formation of singlet oxygen and other free radicals. PDT is highly efficient in the treatment of solar keratoses and superficial basal cell carcinomas. Initial squamous cell carcinomas also show good response to ALA-PDT. During the last decade, numerous studies on PDT for dermatologic diseases were published, the more important ones are reviewed here.

Aminolevulinic Acid↗