Endothelium-derived hyperpolarizing factor (EDHF)

In vascular tissues, many types of stimulants which release endothelium-derived relaxing factor (EDRF) hyperpolarized the smooth muscle membrane in an endothelium-dependent manner. The hyperpolarizations were resistant to inhibitors of the actions of EDRF, thereby suggesting that they were elicited by an unidentified substance called endothelium-derived hyperpolarizing factor (EDHF). The EDHF induced hyperpolarization was produced by an increase in K(+)-permeability of the membrane, and was one of the factors to induce endothelium-dependent vasodilations. Release of EDHF required an increase in endothelial Ca2+, due either to release of Ca2+ from intracellular storage or to its influx from the external media.

The contraction of stunned myocardium: isovolumetric bulging and wasted ejection shortening in dog heart

OBJECTIVE

The aim of the study was to assess the contraction of myocardium stunned by repetitive brief coronary occlusions by examining the response to alterations in loading and inotropy of systolic contraction on isovolumetric and ejection phase shortening.

METHODS

Fourteen open chest anaesthetised dogs were used for the studies. After destruction of the sinus node, the heart was atrially paced and atrial extrasystoles were introduced followed by a short (400 ms) or long (700 ms) postextrasystole. The left anterior descending coronary artery was occluded for 5 min and reperfused for 10 min a total of eight times to produce stunned myocardium, followed by a final 60 min of reflow. Regional function was assessed with segment length sonomicrometers.

RESULTS

With successive periods of occlusion there was an increase in the end diastolic segment length and a progressive decrease in total percent systolic shortening (baseline 22.3%, 1st reflow 14.5%, 8th reflow 7.9%) with some recovery after 60 min of reflow (12.0%). This was predominantly due to the development of bulging during isovolumetric systole (4.5%, -4.9%, and -8.3%, respectively) which diminished during 60 min recovery to -3.1%. Ejection shortening was relatively constant (17.8%, 19.4%, 16.3%, and 15.1%, respectively). Postextrasystolic potentiation resulted in an increased in total percent systolic shortening, but not to the baseline value, as slight isovolumetric bulging persisted. Similar changes were seen with the short and long postextrasystoles although the latter had a greater increase in ejection shortening.

CONCLUSIONS

The decrease in function after repetitive occlusion and reflow is predominantly due to bulging during isovolumetric systole which persists after postextrasystolic potentiation in our model of stunned myocardium.

A cyclic AMP-responsive DNA-binding protein (CREB2) is a cellular transactivator of the bovine leukemia virus long terminal repeat

To gain insight into the cellular regulation of bovine leukemia virus (BLV) trans activation, a lambda-gt11 cDNA library was constructed with mRNA isolated from a BLV-induced tumor and the recombinant proteins were screened with an oligonucleotide corresponding to the tax activation-responsive element (TAR). Two clones (called TAR-binding protein) were isolated from 750,000 lambda-gt11 plaques. The binding specificity was confirmed by Southwestern (DNA-protein) and gel retardation assays. Nucleotide sequence analysis revealed that TAR-binding protein is very similar to the CREB2 protein. It contains a leucine zipper structure required for dimerization, a basic amino acid domain, and multiple potential phosphorylation sites. A vector expressing CREB2 was transfected into D17 osteosarcoma cells. In the absence of the tax transactivator, the CREB2 protein and the cyclic AMP-dependent protein kinase A activate the BLV long terminal repeat at a basal expression level: trans activation reached 10% of the values obtained in the presence of tax alone. These data demonstrate that CREB2 is a cellular factor able to induce BLV long terminal repeat expression in the absence of tax protein and could thus be involved in the early stages of viral infection. In addition, we observed that in vitro tax-induced trans activation can be activated or inhibited by CREB2 depending on the presence or absence of protein kinase A. These data suggest that the cyclic AMP pathway plays a role in the regulation of viral expression in BLV-infected animals.

Practical applications of Beam's Eye View-based treatment planning to head and neck sites

Because of the complex anatomy of the structures involved by tumor as well as of the critical normal structures, treatment planning for advanced or spatially irregular cancers of head and neck sites is often extremely challenging. Computerized axial tomographic scanning is frequently invaluable in delineating tumor extension into areas inaccessible to physical examination. Our Beam's Eye View Planning (BEVP) capability allows us to incorporate this radiographic information accurately into actual plans used in the clinic. Over the past 2 1/2 years, we have applied this technique to 31 selected head and neck cancer patients at Michael Reese/University of Chicago Center for Radiation Therapy. Tumors were chosen on the basis of anatomical complexity: most involved multiple head and neck sites including orbit, skull base, paranasal sinuses and cavernous sinus. In all cases, radiation tolerance of critical normal structures including spinal cord, brain stem, optic chiasm, and eye had to be considered. With careful use of rigid immobilization devices and the outlining of several normal structures for purposes of alignment, we had no difficulty applying our BEVP technique to clinical simulations. Oblique field blocking was especially facilitated by BEVP. We found the BEVP technique very useful to assure that tumor coverage was adequate and tolerance of normal tissues not exceeded.

Nitroarginine-sensitive and -insensitive components of the endothelium-dependent relaxation in the guinea-pig carotid artery

In the guinea-pig carotid arteries, nitroarginine elevated the resting tension (greater than 3 x 10(-6) M) and enhanced the noradrenaline (NA)- and high-potassium (high-K, 29.6 mM) induced contractions (greater than 10(-7) M), in a concentration-dependent manner, with no significant change in the resting membrane potential and depolarizations elicited by NA or high-K. ACh (10(-6) M) relaxed the muscles precontracted with NA or high-K by 96 or 46% of the contraction, respectively. In the presence of nitroarginine (10(-5) M) for 1-3 h, the ACh-induced relaxation was reduced to 40 or 0% of the NA- or high-K-contractions, respectively. In tissues contracted with NA and exposed to nitroarginine, the ACh-induced relaxation changed from a sustained to a transient form. ACh relaxed the muscles to a similar extent, at any given level of tension, as elevated by different concentrations of NA to 1-3 times the level produced by 10(-6) M NA, either in the presence or absence of nitroarginine. ACh (greater than 10(-8) M) produced a transient hyperpolarization of the membrane, in an endothelium-dependent manner, and the responses were blocked by atropine (10(-6) M) or high-K solution, but not by NA or nitroarginine. We propose that 1) endothelium-derived hyperpolarizing factor (EDHF) is produced by pathways independent of the biosynthesis of endothelium-derived relaxing factor (EDRF), 2) the sustained release of EDRF maintains the muscle tone at a low level, and 3) the endothelium-dependent relaxation is produced by both EDRF and EDHF, and they elicit sustained and transient relaxations, respectively.

Two FGF receptor genes are differentially expressed in epithelial and mesenchymal tissues during limb formation and organogenesis in the mouse

Fibroblast growth factors (FGFs) can influence the growth and differentiation of cultured cells derived from neuroectoderm, ectoderm or mesenchyme. The FGFs interact with a family of at least four closely related receptor tyrosine kinases that are products of individual genes. To investigate the role of FGFs in the growth and differentiation of embryonic tissues and to determine whether the individual FGF receptor genes might have specific functions, we compared the localization of mRNA for two FGF receptor genes, FGFR1 (the flg gene product) and FGFR2 (the bek gene product), during limb formation and organogenesis in mouse embryos (E9.5-E16.5). Although the two genes were coexpressed in some tissues, the differential expression of FGFR1 and FGFR2 in most embryonic tissues was striking. FGFR1 was expressed diffusely in mesenchyme of limb buds, somites and organ rudiments. In contrast, FGFR2 was expressed predominantly in the epithelial cells of embryonic skin and of developing organs. The differential expression of FGFR1 and FGFR2 in mesenchyme and epithelium respectively, suggests the receptor genes are independently regulated and that they mediate different functions of FGFs during development.

Augmentation of cisplatin (DDP) cytotoxicity in vivo by DL-buthionine sulfoximine (BSO) in DDP-sensitive and-resistant rat ovarian tumors and its relation to DNA interstrand cross links

DDP treatment (1.2 mg/kg x 5) prolonged the mean survival time (MST) of rats bearing an experimental ovarian tumor (0-342) from 16.4 to 51.1 days, with one of ten rats surviving more than 90 days. Administration of D,L - buthionine sulfoximine (BSO) (24 and 2 h prior to DDP, respectively) before the last two doses of DDP had no significant effect on DDP therapeutic activity, while daily combination of DDP with BSO (BSO 2 h prior to DDP) throughout the treatment significantly increased MST to 69 days (p less than 0.05, vs. DDP alone), with three of ten rats surviving more than 90 days. In the DDP resistant counterpart (0-342/DDP), on the other hand, DDP alone showed only a slight increase of MST (11.6 days in DDP group vs. 10.7 days in control group), addition of BSO to DDP treatment further prolonged MST to 13.3 days (p less than 0.01 vs. DDP alone). The formation of DNA interstrand cross links (DNA-ISCL) was found to be higher in 0-342 than in 0-342/DDP cells in vitro with a maximum at 24 h following 1 h exposure to DDP. BSO depleted the intracellular GSH level in a dose - and time - dependent manner in the two cell lines. Pretreatment with BSO resulted in a 7.4% increase in DNA-ISCL by DDP in 0-342 cells but a 39% increase in 0-342/DDP cells, which may partially account for chemosensitization of BSO to DDP in vivo. Our result that the chemosensitizing effect of BSO, through depletion of cellular GSH, is more significant in the DDP sensitive O-342 tumor than in its DDP resistant subline in vivo underlines that BSO should be used as a chemosensitizer in combination with DDP at the beginning of chemotherapy for clinical trial.

Karyotypic change from heteroploidy to near diploidy associated with development of cisplatin resistance in a rat ovarian tumour cell line

In a rat ovarian tumour cell line a 33-fold resistance to cisplatin (O-342/DDP) was developed in vitro by continuous exposure of the parental cell line (O-342) to stepwise increase cisplatin concentration in the culture medium. Both cell lines had a similar growth rate in vitro. Development of resistance was accompanied by a change of the karyotype from heteroploidy in chemosensitive O-342 cells to near diploidy in resistant O-342/DDP cells as shown by chromosome number distribution. This finding was confirmed by measuring cellular DNA content using flow-cytometry analysis. Flow karyotyping showed significant differences in chromosomal DNA contents between both cell lines. Our results suggest that the parent line O-342 consists of at least two subpopulations, a cisplatin-sensitive and a cisplatin-resistant one, corresponding to hyperploidy and near diploidy, respectively. Continuous cisplatin exposure of O-342 cells selectively killed the sensitive fraction, resulting in the karyotypic change observed.

Cryptosporidiosis facilitated by murine retroviral infection with LP-BM5

LP-BM5 murine leukemia virus infection caused alterations in splenic T cell subsets in adult C57BL/6 female mice. Prolonged infection resulted in increased immunosuppression and a concomitant decreased resistance to Cryptosporidium parvum infection. Significant Cryptosporidium colonization of the intestinal villi was seen 10 days after oral challenge in mice infected with murine retrovirus for 3 months but not in non-virally infected controls. Parasite numbers per villus of retrovirally infected mice were 20-fold higher than in controls, which showed only occasional parasites. Feces from most virally infected mice but none from controls contained oocysts. Cryptosporidium infection in mice after 4 and 5 months of retroviral infection was accompanied by severe immunosuppression and parasite levels 50-5000 times higher than in controls. A high level of infection persisted 21 days after Cryptosporidium challenge in virally infected mice, while controls cleared their transient and marginal infection. These results further characterize LP-BM5 infection as a murine model of retrovirally induced acquired immune deficiency.

[Radionuclide bone scan using single-photon emission-computed tomography in detecting oral and maxillofacial tumor infiltrating to the jaws]

83 cases (including 53 cases of patients and 30 cases of normal volunteer) of SPECT bone scan had been studied for detecting oral and maxillofacial tumor infiltrating to the jaws. The results was contrasted with X-ray, operation and pathology, and indicated that SPECT bone scan could reveal the early tumor infiltrating to the jaws and accurate extent of tumor lesions, more accurate than X-ray. SPECT provided us more important information about the preservation of the jaw and extent of bone resection.

Frequency splitting of degenerate spherical cavity modes: stimulated Raman scattering spectrum of deformed droplets

High-resolution interferometric spectra of the stimulated Raman scattering (SRS) spectra from flowing ethanol droplets are presented. The linewidths of the SRS peaks are less than 0.005 cm(-1), and the equal frequency spacings of the SRS peaks are an order of magnitude smaller than the spacings for morphology-dependent resonances of a perfect sphere. The observed results from droplets that are deformed by inertial effects are consistent with T-matrix and perturbation predictions of frequency splitting into the various azimuthal modes of a (2n + 1)-degenerate morphology-dependent resonance with angular momentum n in a perfect sphere.

[Pharmacological studies on warming the middle-jiao to alleviate pain by Pericarpium Zanthoxyli]

The pharmacological effects of the ethereal extract and aqueous extract of Pericarpium Zanthoxyli on warming the middle-jiao to alleviate pain have been studied. It is suggested that the effects of Pericarpium Zanthoxyli on antagonizing ulcer, and inflammatory and functional diarrheas, protecting liver, and correcting gastrointestinal disorder are the connotation of its warming the middle-jiao to alleviate pain, its analgesic effect helps to relieve various abdominal pains.

[The relation between results of thyrotropin-releasing hormone stimulation tests (TRH-ST), dexamethasone suppression test (DST) and urinary MHPG. SO4 excretion in depressive patients]

Thyrotropin-releasing hormone stimulation test (TRH-ST) was performed in 68 depressive patients, 25 normal subjects and 4 schizophrenics. Dexamethasone suppression test (DST) and urinary MHPG. SO4 determination was also administered in part of this depressive patients. Our data show that some of depressive patients suffered from the dysfunction of hypothalamic-pituitary-thyroid axis, and this dysfunction was not related to the dysfunction of hypothalamic-pituitary-adrenal axis and urinary MHPG. SO4 excretion. A blunted TSH response to TRH was a "STATE MARKER" for some of depressive patients.

[Studies on warming the middle-jiao and analgesic effect of flos Caryophylli]

The effects of water extract and ether extract of Flos Caryophylli have been investigated by four experimental gastric ulcer models, choleresis in rats, two diarrhea models in mice, two pain stimulations in mice, and acute liver injury induced by CCl4 in rats. The results suggest that the action of Flos Caryophylli on dispelling the cold by warming the middle-jiao and curing abdominalgia is related to its anti-ulcer, choleresis increasing, anti-diarrhea and analgesic functions.

Hyperpolarization of arterial smooth muscle induced by endothelial humoral substances

A sandwich preparation was obtained by placing a segment of the endothelium-free guinea pig coronary artery over the intact carotid artery with the objective being to determine whether the endothelium-dependent hyperpolarization by acetylcholine chloride (ACh) is mediated by a humoral factor. ACh hyperpolarized the sandwiched coronary smooth muscle membrane, the amplitude being larger than that of the carotid artery and smaller than that of the intact coronary artery. When spontaneously active smooth muscles (stomach antrum or portal vein) were used as the donor tissue, no electrical signal was transducted to the overlying coronary smooth muscles. In the sandwiched coronary artery, the ACh-induced hyperpolarization was not inhibited by ouabain, indomethacin, or nitroarginine. Pinacidil hyperpolarized the coronary smooth muscle membrane; the responses were inhibited by glybenclamide but not by tetraethylammonium chloride (TEA). The ACh-induced hyperpolarization was inhibited by TEA but not by glybenclamide. These results suggest that the ACh-induced hyperpolarization is mediated by an endothelium-derived humoral substance (endothelium-derived hyperpolarizing factor). Possible contribution of Ca-dependent K channels, but not ATP-sensitive K channels, to the endothelium-derived hyperpolarizing factor-induced hyperpolarization was considered.

[Pharmacokinetic-pharmacodynamic model of magnesium sulfate in treatment of pregnancy-induced hypertension]

Ten pregnancy-induced hypertension gravidas aged 24-36 (28.1 +/- 3.31) yr were infused iv with fast (7.5 g in 1 h) and slow (7.5 g in 5 h) rates consecutively. Blood pressure were measured and blood samples were collected at 0, 1, 6, 7, 9, 11, 15 h. The drug concentration of each sample in the serum was determined by colorimetric method. The integrated pharmacokinetic and pharmacodynamic model was used to analyze the data. The serum data were fitted to a biexponential equation and the effect data were fitted to a sigmoid Emax model. Their pharmacodynamic parameters were: Kco = 0.52.h-1, T1/2(kco) = 1.33 h, Emax = 20.5% Cc (50) = 6.15 micrograms.ml-1), y = 3.64. kco was not equal to k21 of the mammillary model. It shows that the site of action is situated in the effect compartment. The predicted effect could last 24 h.

Endothelium-dependent hyperpolarization elicited by adenine compounds in rabbit carotid artery

Electrical responses of the membrane of intimal and adventitial smooth muscle cells of the rabbit carotid artery to ATP, ADP, AMP, and adenosine were recorded. In intimal cells, these compounds hyperpolarized the membrane. Mechanical removal of the endothelium altered the responses to ATP and ADP to one of a transient depolarization, with no alteration of the response to AMP and adenosine. In the adventitial cells, ATP and ADP produced a transient depolarization, whereas AMP and adenosine produced a sustained hyperpolarization, irrespective of the presence or absence of the endothelium. In tissues with an intact endothelium, 5'-adenylylimidodiphosphate tetralithium salt and alpha,beta-methylene ATP (mATP) transiently depolarized the membrane in these smooth muscles. In case of stabilization with mATP, only hyperpolarization was generated by ATP, in an endothelium-dependent manner. Our interpretation of these observations is that 1) ATP and ADP depolarize smooth muscle membrane by a direct action and hyperpolarize the membrane indirectly through the release of endothelium-derived hyperpolarizing factor, 2) AMP and adenosine hyperpolarize the membrane, independently of the endothelium, and 3) ATP receptors present on the endothelial cell membrane differ from those on smooth muscle membrane.