Sex-dependent liver colonization of human melanoma in SCID mice—role of host defense mechanisms

The possibility that endocrine factors may influence the clinical course of malignant melanoma is suggested by the superior survival data of women. In preclinical models we observed a higher rate of colony formation by human melanoma cells in male compared to female SCID mice, but only in the case of the liver and not in other organs. The gender difference could be seen at an early phase of colony formation. On the other hand, in our human melanoma cell lines we failed to detect steroid receptor protein expression, and treatment with sex hormones did not considerably influence their in vitro behavior. Investigating the possible contribution of host cells to the observed gender difference, we performed in vivo blocking experiments applying pretreatment of the animals with Kupffer cell inhibitor gadolinium chloride and the NK cell inhibitor anti-asialo GM1 antibody. While Kupffer cell blockade enhanced melanoma liver colonization equally in the two sexes, a more prominent increase was observed in female than in male mice in the case of NK cell inhibition. Further supporting the importance of NK cells in the lower liver colonization efficiency of melanoma cells in females, gender difference in colony formation was lost in NSG mice lacking NK activity. Although in humans no organ selectivity of gender difference in melanoma progression has been observed according to data in the literature, our results possibly indicate a contribution of natural host defense mechanisms to gender difference in survival of patients with melanoma or other tumor types as well.     

HbA<Subscript>1c</Subscript> levels and erythrocyte transport functions in complication-free type 1 diabetic children and adolescents

Higher erythrocyte sodium-lithium countertransport activity (SLC) is implicated in the development of diabetic nephropathy. Altered glucose homeostasis and genetic susceptibility are claimed to play a role in the elevation of SLC. We aimed to test whether metabolic control or the genetic variants of G protein beta 3 (Gb3) subunits determine SLC and other erythrocyte transport activities in complication-free stage of type 1 diabetes. A total of 96 complication-free type 1 diabetic children and adolescents were enrolled. SLC, Na⁺/K⁺-ATPase (NAK) and Ca²⁺-ATPase (CA) were measured by functional assays in erythrocytes. Gb3-C825T polymorphism was determined by PCR-RFLP. Results were related to HbA_1c and were compared to those of 97 healthy controls. SLC activity was higher in diabetics (387±146 vs. 280±65 mmol/RBC · hour) and correlated with HbA_1c levels (y=0.004x+6.42, r=0.33, n=96, p<0.01). NAK and CA activities were unaltered. The prevalence of ⁸²⁵T allele was similar in the patient and control groups (0.34 vs 0.37) and no differences in enzyme activities were observed between the ⁸²⁵T allele-positive and negative subjects. Although metabolic control correlated with SLC, other membrane functions were not affected. Therefore we hypothesize that the relationship between advanced glycation and SLC elevation is not causative. Rather, a genetic susceptibility for the coexistence of poor metabolic control and higher SLC is more likely. However, the presence of Gb3-C825T variant is not likely to be a risk factor for SLC-elevation and altered metabolic control diabetes. Received: 4 December 2001 / Accepted in revised form: 28 August 2002 Correspondence to B. Vásárhelyi     

Antigenic and genomic differences of two Jasper strains of infectious pancreatic necrosis virus.

Strains of infectious pancreatic necrosis virus (IPNV-Jasper) obtained from two different laboratories were compared serologically with polyclonal and monoclonal antibodies. Nucleotide sequence and restriction endonuclease patterns of 359-bp fragment of genome segment A cDNA were also compared. Substantial differences were found in both analyses that will support the fact that the two Jasper strains are not identical.     

Carbon/carbon implants in oral and maxillofacial surgery--Part 2

In their previous report, the authors presented observations regarding the long-term application of carbon/carbon implants. After evaluating the good functional and aesthetic results, the effect of the human body on the structure and morphology of the implants was investigated with state of the art methods. An implant retrieved from the body after eight years was compared to implants which were sterilized but not implanted (reference). Carbon and oxygen were the main components of both implants, however, as a result of the interaction with the human body the amount of oxygen increased 3-4 times and phosphorus, sulphur, calcium and iron were detectable as trace elements on the surface. The width of the carbon fibres (5-7 μm) building up the implants was not changed during the interaction with the human body. The surface of the implant retrieved from the human body was covered with a 15-17 μm thick layer, not present on the reference implant, having a similar composition to that of the carbon fibres (high amount of calcium that is typical to bone tissue was not detected). According to these results, the structure and the morphology of the implants were not altered notably by the human body.