New Method for Visualization of Vascular Networks in Nonperfused Fixed Tissues

A new method of visualizing the angioarchitecture of tissues has been developed that uses blood components in nonperfused materials. Tissue blocks are fixed in 4% paraformaldehyde and cut with a vibratome into 50-60 μm sections. Endogenous peroxidase in red blood cells is then reduced in the presence of hydrogen peroxide with the resultant oxidation of the chromogen 3,3'-diaminobenzidine (DAB). This generates a dark, highly insoluble reaction product throughout the vascular system. The visualization of vascular components can be further enhanced by exposing the sections to peroxidase-conjugated IgG to increase the background staining of the blood plasma. The technique minimizes preparation artifact and permits the application of morphometric analytical methods, thus allowing parameters such as the volume density of the vascular bed to be quantified.     

Further segregation analysis of the fragile X syndrome with special reference to transmitting males

Summary A new series of 96 pedigrees with the fra(X) syndrome was analysed using complex segregation analysis with pointers, defining affection as any degree of mental impairment. These families were found to exhibit the same segregation pattern as the first series of 110 pedigrees (Sherman et al. 1984). The best estimate for penetrance of mental impairment in males was 79% and in females was 35% for the combined data. Again, there was little evidence for sporadic cases among affected males.Many more intellectually normal transmitting males have been observed since the existence of such males and the concomitant need to investigate the paternal side of pedigrees was recognized. On further investigation of all 206 pedigrees from the old and new data sets, the sibships of nonexpressing males appeared to be different from those of expressing males. Our analysis, using mental impairment as the phenotype, suggested that obligate carrier mothers and daughters of intellectually normal transmitting males are rarely, if ever, mentally impaired and that the sibs of transmitting males are much less likely to be retarded than the sibs of mentally impaired males. Though mothers and daughters of transmitting males are similar in phenotype, the expression of the gene in their offspring appears to be different: the penetrance of mental impairment is higher in offspring of intellectually normal daughters of transmitting males than in offspring of intellectually normal mothers of transmitting males. The implications of these observations for genetic counseling and for genetic models of the fra(X) syndrome are discussed.     

Effects of kainic acid on synaptic transmission in skate electroreceptors (ampullae of Lorenzini)

The effects of kainic acid on synaptic transmission in electroreceptors were investigated in the skate using techniques of uninterrupted superfusion of the synaptic area with a solution containing this substance and then recording the spike activity of single nerve fibers of the ampullae of Lorenzini. Kainic acid at threshold concentrations of the order of 10^–9 M effectively changed spontaneous and evoked activity of the receptors. Level of background activity served as an indication of the effects taking place. During blockage of synaptic transmission produced by magnesium ions the addition of kainic acid to the magnesium-saturated solution restored both spontaneous and evoked activity. It was deduced that the action of kainic acid on skate electroreceptors is of a primarily presynaptic nature.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 18, No. 2, pp. 147–153, March–April, 1986.     

HLA-JY328: Mapping studies and expression of a polymorphic HLA class I gene

The JY328 clone was identified in a human genomic library using cDNA corresponding to mRNA for HLA-B7 as a probe. The L/328 cell line was established by cotransformation of mouse Ltk^– cells with the herpes thymidine kinase gene and clone JY328. On Northern blots, RNA from,L/328 strongly hybridized to an HLA class I probe, and an antigen was recognized by an anti-HLA class I framework antibody on the cell surface. A DNA probe corresponding to a segment of intron 7 was developed by comparing the nucleotide sequence of clone JY328 with that of other HLA class I-type genes. Using the radiolabeled probe to screen Southern blots of DNA from families with siblings exhibiting intra-HLA recombinations, a restriction fragment length polymorphism was revealed —a 1.4 kb BstE II band not present in all individuals. A corresponding fragment was apparent in the base sequence of clone JY328. The occurrence of this band on Southern blots established that JY328 maps distinct from and centromeric to the HLA-C locus and near to the HLA-B locus. Antibody absorption studies and cytotoxicity tests indicated that the JY328 gene product was not an HLA-B antigen but that it did specifically absorb CW7-specific antibody. In sum, these results suggest a novel, polymorphic HLA class I gene which expresses a product serologically similar to HLA-Cw7 but which does not map within the corresponding locus.     

Methyl bromide inhibits ripening and ethylene production in tomato (lycopersicon esculentum mill.) fruit

Tomato fruit ripening and ethylene production were inhibited following treatment with methyl bromide (MB). Methyl bromide significantly delayed ripening initiation in mature-green (MG) fruit and retarded the rate of ripening of turning (T) fruit as measured by color development and flesh softening. Treatment with MB caused an initial transient burst of ethylene production, but the subsequent ripening-associated increase in ethylene was delayed. Ethylene treatment partially overcame MB inhibition in MG fruit but had no affect on T fruit. The inhibition of ethylene production by MB appears to be due to lack of formation of 1-aminocycloprone-1-carboxylic acid (ACC) in MG fruit, whereas in T fruit lack of conversion of ACC to ethylene is indicated. A key feature of MB inhibition of ripening in tomato appears to be reduced sensitivity to ethylene.     

Bladder cancer diagnosis by computer image analysis of cells in the sediment of voided urine using a video scanning system

A video-based computerized semiautomated image analysis system was applied to the diagnostic evaluation of 119 sediments of voided urine: 103 from patients with a broad variety of neoplastic and nonneoplastic disorders of the lower urinary tract and 16 normal controls. Each specimen was presented to the machine as a single cytocentrifuge preparation, preserved in 2% Carbowax in 50% ethanol and stained-by the Papanicolaou method. Five hundred sequential "objects" were scanned within an area of 9 sq mm on each slide. "Objects" of no diagnostic value, such as dirt, debris, inflammatory cells, cell clusters, poorly preserved cells, etc., were eliminated from the final diagnostic analysis by a computer-based hierarchic triage system. The final specimen classifier was based on the cell images identified by the computer as well-preserved normal (NEG), atypical (ATY I), suspicious (ATY II) and malignant (POS) cells. For specimen classification by computer, the four categories of "abnormal," "inadequate," "acellular" and "negative" were defined. For high-grade tumors, the performance of the specimen classifier was generally comparable to the visual diagnosis. The specimen classifier unexpectedly identified twice as many low-grade papillary urothelial tumors as abnormal than did the visual analysis. Several false "alarms" were recorded by computer in patients with benign prostatic hypertrophy and prostatic carcinoma, some of whom had atypical urothelium. One of the 16 negative controls was misdiagnosed by the computer as abnormal. The possibility that the video system recognizes nuclear abnormalities not perceived by the human eye is being investigated further. The details of the computer analysis are reported, and the value of the system is discussed. The system appears to be promising as a future laboratory instrument, although it requires further extensive testing.     

Studies on metatherian sex chromosomes. XII. Sex-linked inheritance and probable paternal X-inactivation of alpha-galactosidase A in Australian marsupials

An investigation of genetic variation in the electrophoretic mobility of the enzyme alpha-galactosidase A (EC 3.2.1.22) has been carried out for 33 species of Australian metatherian (marsupial) mammals. The results are compatible with the enzyme being sex-linked in macropodids (kangaroos and wallabies) and probably in dasyurids (marsupial 'mice', etc.), as it is in eutherian (placental) mammals. The results also suggest that the mode of dosage compensation for this locus is the same as for other sex-linked loci in kangaroos, i.e. paternal X inactivation, rather than the random X inactivation system of eutherian mammals. The bearing of the enzyme mobility data on phylogenetic relationships among macropodid species is discussed.