糖化血清蛋白测定对糖尿病监控临床意义的探讨

目的：对临床确诊糖尿病患同时测定血清葡萄糖(Glu)及糖化血清蛋白(GSP)的含量，观察二的关系，以及糖化血清蛋白水平对于评价近期(2—3周)糖尿病患血糖在体内变化的临床意义进行了观察。方法：血清葡萄糖、糖化血清蛋白测定均采用酶法测定。结果：178例糖尿病患Glu、GSP均正常3l例占17．4％；Glu、GSP均增高107例占60．1％；Glu正常、GSP增高15例占8．43％；Glu增高、GSP正常25例占14％。结论：糖化血清蛋白的含量不受即时血糖的影响，二的变化不成比例性，对评价糖尿病患2～3周病情的控制是一项灵敏可靠的指标，尤其对于住院病人的治疗与监控有一定的意义。     

CMSS-VEPs: Contrast modulated steady state visual evoked potentials: Its neuronal origin and clinical use

CMSS-VEPs are presented as a sensitive, non-invasive functional investigation technique of the visual function, applicable in clinical practice. New improvements of the technique are presented. The underlying neuronal mechanisms are discussed. The clinical use is illustrated in a case of optic neuritis.     

Modulation by a moving texture of cat area 18 neuron responses to moving bars

1. The influence of a moving texture on neuronal responses to a moving bar was tested in 103 area 18 neurons of anesthetized and paralyzed cats. The texture was a two-dimensional noise pattern, the bar moved at optimal speed, and its contrast was adjusted to yield 50% of the maximum response. 2. The moving texture exerted two different but related effects: it suppressed the response of area 18 neurons to the moving bar, and it modulated the direction selectivity of parastriate neurons. These effects were strongest when the texture moved at the same speed or faster than the bar. 3. Genuine suppressive effects of the moving texture were distinguished from lack of summation between bar and texture responses. Suppressive effects of either type were observed in 75% of the area 18 cells and occurred more frequently among C family cells, velocity tuned cells, and in layer 5 than in other groups of cells. 4. The modulation of direction selectivity was distinguished from pseudomodulation because of lack of summation of bar and texture responses. The direction selectivity of 35% of the area 18 cells was modulated by the moving texture. Six different relative direction selectivity (RDS) types were observed in area 18. 5. The neurons of which direction selectivity was modulated by the moving texture occurred predominantly in layers 2-3 and 6, suggesting that they represent a further stage of processing within area 18. 6. Many (75%) area 18 cells responded to the texture moving on its own. Most of these cells respond to isolated features ("grains") in the patterns rather than to the movement of the whole pattern. Cells responding to the movement of the whole pattern were generally C family cells, and their direction selectivity was not modulated by the moving texture. 7. These results are compared with those obtained under identical experimental conditions in area 17. Although suppressive effects are similar in both areas, RDS types are differently distributed in the two areas. 8. The possible origins of the interactions and their functional significance are discussed.     

Identification of non-amplifying CYP21 genes when using PCR-based diagnosis of 21-hydroxylase deficiency in congenital adrenal hyperplasia (CAH) affected pedigrees

Steroid 21-hydroxylase deficiency is among the most common inborn errors of metabolism in man. Characterization of mutations in the 21- hydroxylase gene (CYP21) has permitted genetic diagnosis, facilitated by the polymerase chain reaction (PCR). The most common mutation is conversion of an A or C at nt656 to a G in the second intron causing aberrant splicing of mRNA. Homozygosity for nt656G is associated with profoundly deficient adrenal cortisol and aldosterone synthesis, secondary hypersecretion of adrenal androgens, and a severe form of congenital adrenal hyperplasia (CAH) characterized by ambiguous genitalia and/or sodium wasting in newborns. During the course of genetic analysis of CYP21 mutations in CAH families, we and others have noticed a number of relatives genotyped as nt656G homozygotes, yet showing no clinical signs of disease. A number of lines of evidence have led us to propose that the putative asymptomatic nt656G/G individuals are incorrectly typed due to dropout of one haplotype during PCR amplification of CYP21. For prenatal diagnosis, we recommend that microsatellite typing be used as a supplement to CYP21 genotyping in order to resolve ambiguities at nt656.      

A factor shed by lymphoblastoid cell lines of HLA-B27 positive patients with ankylosing spondylitis, specifically modifies the cells of HLA-B27 positive normal individuals.

Epstein-Barr virus transformed lymphoblastoid cell lines from HLA-B27 positive individuals with ankylosing spondylitis (B27+AS+) release, into the culture medium, a factor capable of specifically modifying the HLA-B27 positive lymphocytes of normal individuals (B27+AS-); this modification results in a phenotypic change similar to that seen on B27+AS+ lymphocytes. This lymphoblastoid cell line derived factor appears to be physically and functionally similar to a factor present in the culture filtrate of certain Klebsiella isolates. Biogel P-100 chromatography of the material released from the cell line indicated a mol.wt of 25,000-30,000, similar to that of the Klebsiella derived factor. Chromatofocusing on a PBE 94 column revealed that cell line derived factor had an isoelectric point of 5.5 (cf. pI 5.4 for the Klebsiella derived factor). Immunoadsorption experiments suggest that the factor from the B27+AS+ cell line shares antigenic determinants with a cell surface component present on certain Klebsiella isolates. These results will form the basis for future studies on the nature of the interaction between HLA-B27 and certain enteric organisms and their products. A better understanding of this association should elucidate some of the early events in the pathogenesis of the seronegative arthropathies.     

The GAP-related domain of tuberin, the product of the TSC2 gene, is a target for missense mutations in tuberous sclerosis

Tuberous sclerosis is an autosomal dominant trait in which the dysregulation of cellular proliferation and differentiation results in the development of hamartomatous growths in many organs. The TSC2 gene is one of two genes determining tuberous sclerosis. Inactivating germline mutations of TSC2 in patients with tuberous sclerosis and somatic loss of heterozygosity at the TSC2 locus in the associated hamartomas indicate that TSC2 functions as a tumour suppressor gene and that loss of function is critical to expression of the tuberous sclerosis phenotype. The TSC2 product, tuberin, has a region of homology with the GTPase activating protein rap1GAP and stimulates the GTPase activity of rap1a and rab5a in vitro. Here we show that the region of homology between tuberin and human rap1GAP and the murine GAP mSpa1 is more extensive than previously reported and spans approximately 160 amino acid residues encoded within exons 34-38 of the TSC2 gene. Single strand conformation polymorphism analysis of these exons in 173 unrelated patients with tuberous sclerosis and direct sequencing of variant conformers together with study of additional family members enabled characterisation of disease associated mutations in 14 cases. Missense mutations, which occurred in exons 36, 37 and 38 were identified in eight cases, four of whom shared the same recurrent change P1675L. Each of the five different missense mutations identified was shown to occur de novo in at least one sporadic case of tuberous sclerosis. The high proportion of missense mutations detected in the region of the TSC2 gene encoding the GAP-related domain supports its key role in the regulation of cellular growth.