摘要:

Photosensory membrane degradation in crayfish occurs at first in multi‐vesicular bodies (MVBs) and then, with the aid of lysosomal enzymes, in lysosome related lamellar bodies. In organ culture experiments with the isolated crayfish retina (Orconectes limosus) small screening pigment‐like granules became visible under the electron microscope in such lamellar bodies and suggested a possible relation of photosensory membrane degradation and screening pigment granule synthesis. Chloroquine, an inhibitor of lysosomal activity, when added to the culture medium reduced the appearance of screening pigment‐like granules in lamellar bodies, but led to the appearance of these granules in mature MVB's, indicating the involvement of lysosomal enzymes in the formation of pigmented lamellar bodies. In a second set of experiments the effect of bright light on the screening pigment granule ultrastructure of crayfish phoreceptors was investigated. It was found that after bright light exposure large numbers of little screening pigment granules (0.15–0.3 μm) were located between or close to rhabdomeral microvilli that were not at these sites in crayfish kept under natural light. MVB's were also reduced in size, and among the little screening pigmentary organelles granules of different electron density and morphology appeared. Additionally, vesicle flux to little screening pigment granules was detected. The screening pigment granules of the little type did not seem to be transported close to or between the microvilli, but appeared to be synthesized at these sites within lit

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00299.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The main characteristics of L‐tyrosine (L‐Tyr) uptake by B16/F10 malignant melanocytes are reported. This amino acid can be taken up by two systems, both of them being saturable. The first one would be system L. This system can be studied in cells preloaded with amino acids that are a good substrate for system L, such as L‐methionine or L‐tryptophan. The kinetic parameters for L‐Tyr uptake by this transport system are Vm= 6.5 pmol L‐Tyr/103cell·smin and Kmaround 130 μM. The second system, probably the system ASC, shows lower capacity but higher affinity than the former. This system can be detected only in cells previously depleted of amino acids, showing approximate kinetic values of Vm0.05 pmol L‐Tyr/103cell·smin and Kmaround 5 μM. It is shown that the increase in cell density yields a decrease in the rate of L‐Tyr uptake by system L, but this increase does not affect the high affinity system. α‐MSH does not affect significantly the L‐Tyr uptake by both systems. 2‐Amino bicyclo‐(2,2,l)‐heptane‐2‐carboxylic acid produces a remarkable inhibition of the rate of L‐Tyr uptake, but α‐methylaminoisobutyric acid does not affect the rate of transport of this amino acid. The absence of sodium produces a slight but reliable decrease in the rate of L‐Tyr uptake, supporting the involvement of two different transport systems. The ionophores monensin and nigericin enhance the transport by system L, but this effect is suppressed by the presence of ouabain. This finding indicates that the (Na + ‐K+)‐ATPase is essential for the stimulating action of ionophores. Finally, it is shown that γ‐glutamyl cycle is not involved in L‐Tyr uptake, since the inhibition of γ‐glutamyl transpeptidase by peri

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00300.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Melanocytic cells from white Angora goats were studied in vivo and in vitro. The histopathology of pigmented areas of skin from the most common sites of melanoma (solar‐exposed areas of the ear, face, and perineum) resembled that of the epidermal melanocytes in Hutchinson's melanotic freckle in humans. Seven melanoma biopsies from 6 Angora goats showed histopathological features in common with human melanoma. A melanoma cell line, GM‐1, was established in culture from a lymph node metastastis obtained from an animal that had a primary tumor excised and later developed extensive metastatic disease. GM‐1 cells were mainly diploid, amelanotic, proliferated rapidly, spontaneously formed vacuolated cells, and were tumorigenic in nude mice. The species of origin of the GM‐1 line was confirmed by isozyme profiles. GM‐1 cultured cells and the original biopsy both expressed S‐100 protein and tyrosinase antigen. Using GM‐1 cells as the immunogen, a monoclonal antibody (MoAb 1F1) was derived that reacted strongly with a 116 kDa antigen in 50% of the GM‐1 cells, but had little activity with goat fibroblasts (GM‐F) or with human melanoma cells. GM‐F, on the other hand, yielded more intense staining than GM‐1 with an intermediate filament antibody (IFA), reacting with a 58 kDa antigen in both cell lines. The sensitivity of GM‐1 to anticancer agents was similar to that of human melanoma cells. The pathology of caprine melanoma and its association with sun‐exposed sites in relatively young animals suggest that it may be a suitable model for studying induction of mel

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00301.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The pharmacokinetic behaviour of 4‐hydroxyanisole (4HA) has been studied in ten female patients with recurrent malignant melanoma confined to the lower limb. Ten grams of 4HA was infused twice each day via a catheter placed in the common femoral artery for a maximum of 4 days. Blood samples were collected after the first and fourth infusions in all patients and the serum 4HA concentration assayed. Following infusion, the serum 4HA concentration declined in two phases, the half‐lives (t1/2) of the distribution and elimination phases being 6.3 and 70.9 min, respectively. The serum 4HA concentrations and area under the curve (AUC) declined significantly between the first and fourth infusions. There was a significant rise in the apparent volume of distribution (VD) of 4HA between these times but no change in the t1/2of the elimination phase or the clearance rate. It is concluded that there is no evidence that enzyme induction influences the clearance of 4‐hydroxyanisole from the bloodstream in the short‐term. However, it may be appropriate to adjust dosage regimens to take account of the change in VD that occurs wi

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00302.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The boron‐containing melanin precursor analoguep‐boronophenylalanine (BPA) has previously been shown to selectively deliver boron to pigmented murine melanomas when administered in a single intragastric dose. If boron neutron capture therapy is to become a clinically useful method of radiation therapy for human malignant melanoma, the boron carrier must be capable of delivering useful amounts of boron to remote tumor sites (metastases) and to poorly pigmented melanomas. We have now determined the ability of BPA to accumulate in several nonpigmented melanoma models including human melanoma xenografts in nude mice. The absolute amount of boron in the nonpigmented melanomas was about 50% of that observed in the pigmented counterparts but was still selectively concentrated in the tumor relative to normal tissues in amounts sufficient for effective neutron capture therapy. Single intragastric doses of BPA resulted in selective localization of boron in the amelanotic Greene melanoma carried in the anterior chamber of the rabbit eye and in a pigmented murine melanoma growing in the lungs. The ratio of the boron concentration in these tumors to the boron concentration in the immediately adjacent normal tissue was in the range of 3:1 to 4:1. These distribution studies support the proposal that boron neutron capture therapy may be useful as a regional therapy for malignant melan

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00303.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Irides from adult Ringed Turtle Doves (Streptopelia risoria) were examined using both light and electron miscroscopy. The anterior surface of the iris stroma contained numerous large venous sinuses overlying bright yellow pigment cells which we classified as “reflecting xanthophores.” The pigment cells were filled with irregularly arranged yellow reflecting crystals and occasional pterinosome‐like structures. The irides were extracted in NaOH and the extracted pigments analyzed using paper chromatography and spectro‐photometry. A unique bright orange fluorescent band was found in the iris extract, but the chemical nature of the band was not determined. Although guanine was expected to be a major component of the reflecting "platelets," based on previous work with other Columbiformes, it could not be demonstrated chromatographically or spectrophotomet

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00304.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00305.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00306.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY