Ensemble noise and current relaxation analysis of K+ current in single isolated salivary acinar cells from rat

The K⁺ channel in rat parotid gland acinar cells were investigated by ensemble current noise analysis in single isolated cells employing the giga-seal whole cell current recording mode. Sets of 20–40 identical de- and hyperpolarization voltage steps were applied and the resultant current records were processed by computer to obtain the mean and the variance of the current. The time-course of the mean current could be fitted by the sum of two exponentials, suggesting a 3-state model. The simplest plausible hypothesis is a model with one open and two closed states. Assuming this model, the relationship between the variance (₂) and the mean current (I) could be fitted by the function ₂/I=i–I/N. The estimated single channeli/V-relations were similar to those taken from single channel current recordings, and the size of the population of channels per cell (N) was 76±26 (n=12). The validity of the model was tested by a successful simulation of the time-course of the variance.     

Congenital malformation of the feet with low body height

Among 75 members of a Danish family, 12 were found with a syndrome not previously described. Clinically, the syndrome consists of low body height and rigid flat feet, with weight-bearing pain in the feet. Radiologically, the deformation of the feet is a medial synostosis between the talus and the calcaneus combined with ankle joint dysplasia. The cause of the syndrome is most probably an autosomal dominant gene with complete penetrance. No linkage was found of the gene to 18 marker genes.     

Ring chromosome 22 and neurofibromatosis

Variable constitutional mosaicism, mos45,XY,-22/46,XY,-22,+mar/46,XY,-22,+r(22)/47,XY,-22,+r(22)+mar/ 47, XY,-22,+r(22)*2, was found in PHA-stimulated peripheral blood, in a lymphoblastoid cell line and in cultured skin fibroblasts from a mentally retarded patient with neurofibromatosis. Both the ring chromosome and the small extra marker chromosome stained positively by in situ hybridization with a chromosome 14/22-specific alphoid repeat probe. DNA dosage analysis showed constitutional loss of one copy of the arylsulfatase A gene (ARSA), consistent with its terminal location on 22q. There was no evidence of constitutional loss of D22S1 or D22S28 which flank the neurofibromatosis type 2 (NF2) locus. Analysis of two DNA samples from a skin neurofibroma indicated retainment of two copies of D22S1, whereas the results were ambiguous with respect to tumor-specific loss of one copy of D22S28. It is suggested that the development of neurofibromatosis of unclear type in two r(22) carriers might be associated with somatic mutation of the NF2 locus due to instability of the ring chromosome(s), and in analogy, that somatic mutation of either NF1 or NF2 may account for some cases of neurofibromatosis which do not meet the criteria of either NF1 or NF2. The occurrence of seminoma in the proband may be fortuitous, but could also be due to the presence of a seminoma-associated locus on chromosome 22.     

Circulating immune complexes in ulcerative colitis.--II. Correlation with serum protein concentrations and complement conversion products

Several serum proteins were quantified in twenty-two patients with active ulcerative colitis, and the findings were related to disease activity and occurrence of circulating immune complexes (IC). Conversion of C3 was significantly more frequent in the IC-positive group (eight patients) as compared to the IC-negative group (fourteen patients). Factor B was demonstrable in fifteen out of the twenty-two patients and seven out of the eight IC-positive patients had detectable levels of factor B. There was no difference between the IC-positive and the IC-negative group as regards serum concentrations of the complement factors C3, C4 and factor B, or serum orosomucoid, albumin, IgM and IgG. In contrast, the serum IgA levels tended to be reduced in the IC-positive group. C3 and factor B were significantly elevated in four patients with severe disease activity. In addition, C3, factor B and C4 concentrations showed a positive correlation to the serum orosomucoid levels. The serum concentrations of orosomucoid and albumin were inversely correlated to each other.     

Protein kinase C activation modulates tumour necrosis factor-alpha priming of human neutrophils for zymosan-induced leukotriene B4 release.

Neutrophil (PMN) activation by the yeast component zymosan involves the complement receptor type 3 (CD11b/CD18). Recombinant human tumour necrosis factor-alpha (rhTNF-alpha) augmented the zymosan-stimulated leukotriene B4 (LTB4) release from PMN, reaching a fourfold increase at 10(-9) M. Co-incubation of PMN with 10(-9) M rhTNF-alpha and staurosporine resulted in a further dose-dependent increase, which became significantly greater than a purely additive effect at a staurosporine concentration of 10 nM. This synergy was maintained at all doses of staurosporine tested. In addition, doses of phorbol 12-myristate 13-acetate (PMA) that do not activate protein kinase C (PKC) (below 10(-9) M) also augmented the zymosan-stimulated release of LTB4. However, doses of PMA above 10(-9) M progressively inhibited the response to levels below that of zymosan alone. Staurosporine at 50 nM completely prevented, and 10(-9) M rhTNF-alpha partially but significantly (P less than 0.02 at 10(-8) M PMA, P less than 0.01 at 10(-7) M PMA) reversed, this high-dose PMA inhibition. PKC activation thus opposes the priming effect of rhTNF-alpha on neutrophils, while PKC inhibition may enhance the ability of rhTNF-alpha to prime PMN for zymosan activation. The combined effect of rhTNF-alpha and staurosporine suggests an intracellular synergy rather than simply a direct action due to increased zymosan receptor expression. Thus there appear to be mechanisms whereby the responses of neutrophils may be augmented without activating PKC. Indeed, kinase activation may even exert a degree of feedback control that is antagonized by rhTNF-alpha treatment.     

A case of apparent trisomy 21 without the Down''s syndrome phenotype.

We describe a case of apparent trisomy 21 that does not fulfill the criteria for the clinical diagnosis of Down's syndrome (DS). Our patient was subjected to karyotype analysis and found to have full, non-mosaic trisomy 21 in both blood lymphocytes and skin fibroblasts, while examination of the term placenta, which was performed earlier in the course of a different study, had shown mosaicism (73%) for trisomy 21. FISH analysis showed no obvious rearrangement of the DS chromosomal region in any of the chromosomes 21. Molecular analysis using polymorphic markers on chromosome 21 verified the existence of trisomy for the entire long arm of the chromosome and showed that the origin of the extra chromosome was maternal and was probably the result of a mitotic error. In contrast with the above, the clinical evaluation using the Jackson checklist of 25 signs failed to establish the diagnosis of DS. We believe that our patient might present mosaicism in other tissues that are not available for analysis and can be regarded as an extreme example in the continuous spectrum of karyotype phenotype associations in mosaic cases.