Citations

In seven strains of cultured normal human osteoblast-like cells, a mean of 1615 molecules of tritium-labeled 17β-estradiol per cell nucleus could be bound to specific nuclear sites. The nuclear binding of the labeled steroid was temperature-dependent, steroid-specific, saturable, and cell type-specific. These are characteristics of biologically active estrogen receptors. Pretreatment with 10 nanomolar estradiol in vitro increased the specific nuclear binding of progesterone in four of six cell strains, indicating an induction of functional progesterone receptors. RNA blot analysis demonstrated the presence of messenger RNA for the human estrogen receptor. The data suggest that estrogen acts directly on human bone cells through a classical estrogen receptor-mediated mechanism.

A sequencing method called genomic amplification with transcript sequencing (GAWTS) is described that is based on amplification with the polymerase chain reaction (PCR). GAWTS bypasses cloning and increases the rate of sequence acquisition by at least fivefold. The method involves the attachment of a phage promoter onto at least one of the PCR primers. The segments amplified by PCR are transcribed to further increase the signal and to provide an abundance of single-stranded template for reverse transcriptase-mediated dideoxy sequencing. An end-labeled reverse transcriptase primer complementary to the desired sequence generates the additional specificity required to generate unambiguous sequence data. GAWTS can be performed on as little as a nanogram of genomic DNA. The rate of GAWTS can be increased by coamplification and cotranscription of multiple regions as illustrated by two regions of the factor IX gene. Since GAWTS lends itself well to automation, further increases in the rate of sequence acquisition can be expected.

Human papillomavirus DNA has been detected in the semen of three patients, two of whom have severe chronic wart disease. These data support the contention that sexual transmission of human papillomavirus DNA could occur via semen, a possibility suggested by epidemiological data on the sexual transmission of human papillomavirus.

Apolipoproteins A-1 and A-2 were purified from human plasma. At concentrations present in human bile these proteins prolonged the nucleation time of cholesterol monohydrate crystals when added to model systems of supersaturated bile. In contrast, apolipoprotein C-3 and other serum proteins did not have this effect. Also, when human gallbladder bile was fractionated by gel filtration chromatography, apolipoproteins A-1 and A-2 were among the proteins present in a fraction of bile enriched in potent inhibitors of cholesterol crystal nucleation. These findings suggest that apolipoproteins A-1 and A-2 in supersaturated human gallbladder bile could inhibit the rate of formation of solid cholesterol crystals and thus help to prevent spontaneous cholesterol gallstone formation in humans.

Colorectal tumor DNA was examined for somatic instability at (CA) n repeats on human chromosomes 5q, 15q, 17p, and 18q. Differences between tumor and normal DNA were detected in 25 of the 90 (28 percent) tumors examined. This instability appeared as either a substantial change in repeat length (often heterogeneous in nature) or a minor change (typically two base pairs). Microsatellite instability was significantly correlated with the tumor's location in the proximal colon ( P = 0.003), with increased patient survival ( P = 0.02), and, inversely, with loss of heterozygosity for chromosomes 5q, 17p, and 18q. These data suggest that some colorectal cancers may arise through a mechanism that does not necessarily involve loss of heterozygosity.

Aggregating autologous platelets caused contraction of isolated rings of canine left circumflex arteries. The contractions were augmented after removal of the endothelium and were attenuated by serotonergic antagonists. During contraction caused by prostaglandin F 2α , aggregating platelets caused a transient increase in tension followed by a profound relaxation of arteries with endothelium, but caused only further contraction of arteries without endothelium. These observations demonstrate the importance of the vascular endothelium in opposing the constriction of coronary vessels caused by 5-hydroxytryptamine and other substances released from aggregating platelets.

Thrombin, the central regulatory enzyme in coagulation, when incubated in nanomolar concentrations with murine neuroblastoma cells produced a rapid and marked increase in tritiated guanosine 3′,5′-monophosphate (cyclic GMP) formation that was blocked by hirudin and competitively antagonized by dansylarginine N -(3-ethyl-1,5-pentanediyl)amide. Diisopropylphosphofluoridate-inactivated thrombin as well as the serine protease trypsin were markedly less potent and less effective than α-thrombin in producing this effect. Thrombin-stimulated cyclic GMP formation was inhibited by mepacrine and nordihydroguaiaretic acid but unaffected by indomethacin, suggesting that lipoxygenase metabolites of arachidonic acid are involved in the response. These results suggest that a thrombin-like protease in the brain may be involved with the function of neurons or that thrombin interactions with nerve cells, such as those following cerebral hemorrhage or other trauma of the central nervous system, may be important in the subsequent neuropathology.

Using chromosome heteromorphisms and blood cell types as genetic markers, we demonstrated chimerism in a chi46,XX/46,XY true hermaphrodite. The pattern of inheritance of the chromosome heteromorphisms indicates that this individual was probably conceived by the fertilization, by two different spermatozoa, of an ovum and the second meiotic division polar body derived from the ovum and subsequent fusion of the two zygotes. This conclusion is based on the identification of the same maternal chromosomes 13, 16, and 21 in both the 46,XX and 46,XY cells of the patient. In the two cell lines of the chimera, chromosomal markers showed different paternal No. 9 chromosomes and sex chromosomes, as well as the same paternal chromosome 22.

A single intrathecal injection of capsaicin depletes substance P from primary sensory neurons and causes a prolonged increase in the thermal and chemical pain thresholds of the rat but no apparent change in responses to noxious mechanical stimuli.

Transitional cell carcinoma was induced in the bladders of male Fischer rats by 12 oral doses of the carcinogen N -butyl- N -(4-hydroxybutyl)nitrosamine. Feeding of 13-cis-retinoic acid after completion of carcinogen treatment diminished the number and severity of cancers and other proliferative lesions of the bladder.