Differential effects of deuterium oxide on the fluorescence lifetimes and intensities of dyes with different modes of binding to DNA

Isolation of monocytes by plastic adherence alters cell morphology and function. In order to study the effects of cell isolation procedures and subsequent culture on monocyte function, we examined cytoplasmic calcium concentration changes (delta[Ca2+]in) in human monocytes isolated by either negative (magnetic bead) or positive (plastic adherence) selection then stimulated with formyl-Met-Leu-Phe (fMLP), either immediately after isolation, or after 48 h in culture. We have previously shown that fresh adherence-isolated monocytes respond to fMLP with small delta[Ca2+]in and oxidative burst responses, exhibiting larger responses following 48 h of incubation. We now demonstrate that fresh monocytes, prevented from adhering by negative selection, exhibit an even smaller fMLP-induced delta[Ca2+]in, which does not increase during 48 h in culture if cells are kept nonadherent, in Teflon. Calcium responses of adherent, fresh monocytes do not increase if cells are subsequently placed into suspension and maintained nonadherent, but increase if nonadherent cells are permitted to adhere to plastic. Furthermore, augmented fMLP-[Ca2+]in and oxidative burst responses in plastic-adherent cells are restricted to a CD14-high phenotype subpopulation. The CD14-high phenotype also describes a subpopulation of cells that responds to CD4 crosslinking with a rapid delta[Ca2+]in. Induction of a subpopulation of CD14-high expressing cells by adherence may explain in part maturation-induced response changes observed in macrophage but not in monocyte in vitro systems.     

Dissociation between the effects of somatostatin (SS) and octapeptide SS-analogs on hormone release in a small subgroup of pituitary- and islet cell tumors

The effects of somatostatin (SS-14 and/or SS-28) and of the three octapeptide SS-analogs that are available for clinical use (octreotide, BIM-23014 and RC-160) on hormone release by primary cultures of 15 clinically nonfunctioning pituitary adenomas (NFA), 7 prolactinomas, and 2 insulinomas were investigated. In the pituitary adenoma cultures, a comparison was made with the effects of the dopamine (DA) agonists bromocriptine and/or quinagolide. In 5 NFAs, 2 prolactinomas and 1 insulinoma somatostatin receptor (subtype) expression was determined by ligand binding studies and by in situ hybridization to detect sst1, sst2, and sst3 messenger RNAs (mRNAs). Four NFA cultures did not secrete detectable amounts of alpha-subunit, FSH, and/or LH. In the other cultures, hormone and/or subunit release was inhibited by DA-agonists (10 nM) in 9 of 11, by SS (10 nM) in 7 of 11, and by octapeptide SS-analogs (10 nM) in 3 of 10 cultures. In three NFA cultures, hormone release was sensitive to SS but not to SS-analogs. In all cultures, except for one, DA-agonists were the most effective in inhibiting hormone release. In the prolactinoma cultures, PRL release was inhibited by DA-agonists (10 nM) in 7 of 7, by SS in 4 of 4, and by octapeptide SS-analogs in 3 of 7 cultures. A dissociation between the effects of SS and SS-analogs was found in 3 cases. In the cultures sensitive to both bromocriptine and SS-28, bromocriptine was the most potent compound in 2 out of 4 cultures. In the 2 other cultures, both compounds were equally effective. In 2 insulinoma cultures, insulin release was inhibited by SS, and by octapeptide SS-analogs in only one. The presence or absence of an inhibitory effect by octreotide was in all cases in parallel with the presence or absence of the inhibitory effect by BIM-23014 and RC-160. Autoradiographic studies using [125I-Tyr0]SS28 showed specific binding in 4 of 5 NFAs, 1 of 2 prolactinomas, and 1 of 1 insulinoma. Specific [125I-Tyr3]octreotide binding was found in 2 of 5 NFAs, in 1 of 2 prolactinomas, and in the insulinoma. Two NFAs showed binding of SS28, but not of the sst2.5 specific ligand octreotide. The tumors showed variable sst1 and/or sst3 mRNA expression, whereas no sst2 expression was found. In conclusion, a dissociation between the inhibitory effects of SS on the one hand and of the octapeptide SS-analogs octreotide, BIM-23014 and RC-160 on the other hand, is observed in a small subgroup of NFAs, prolactinomas, and insulinomas, suggesting that novel sst subtype specific SS-analogs might be of benefit in the treatment of selected patients with somatostatin receptor positive secreting tumors not responding to octapeptide SS-analogs. However, in the majority of NFAs and prolactinomas, DA-agonists were equally or more effective than SS in the suppression of tumoral secretion products.     

Force-frequency relations in the failing rabbit heart and responses to adrenergic stimulation

Yohimbine, an alpha 2 adrenoreceptor antagonist, enhances norepinephrine (NE) release and increases sympathetic activity. We examined the behavioral, peripheral sympathetic and adrenocortical responses to oral yohimbine in seven healthy controls and 11 patients diagnosed with agoraphobia with panic attacks (PD). Patients did not differ in baseline cardiovascular or neuroendocrine measures from controls despite significantly higher baseline anxiety ratings. Placebo caused no changes in baseline-corrected behavioral, cardiovascular or neurochemical responses in either group. Yohimbine induced a panic episode in six PD patients, but no controls. PD patients had significantly higher severity scores of autonomic anxiety symptoms. Yohimbine significantly raised systolic blood pressure (F = 3.07, P < 0.03), plasma NE levels (F = 12.11, P < 0.00) and cortisol levels (F = 4.82, P < 0.02), but had no effect on epinephrine levels. NE responses were similar in both groups, but patients had higher cortisol responses to yohimbine than controls (F = 7.14, P < 0.01). The correlational pattern between behavioral ratings and neuroendocrine responses in patients was opposite to that observed in controls. Despite similar increases in plasma NE levels between PD patients and healthy controls, PD patients had greater anxiogenic, cardiovascular and cortisol responses to yohimbine. Enhanced post-synaptic adrenoreceptor sensitivity may explain the noradrenergic dysregulation found in panic disorder.     

The glio-toxic mechanism of alpha-aminoadipic acid on cultured astrocytes

Porcine pancreatic phospholipase A2 (PLA2) hydrolyses phosphatidylcholine when in the lamellar state as well as in the micellar state. We have found that alpha-tocopherol, the most active form of vitamin E, is able to inhibit PLA2 activity only toward lamellar fluid membranes, thus protecting phospholipids toward this lytic enzyme. This compound decreases both the initial rate and the extent of hydrolysis. The inhibition is of the non-competitive type and the evidence strongly suggests that it is due to an effect of alpha-tocopherol on the substrate, i.e. the membrane, and not on the enzyme itself. Other tocopherols, such as the isomers beta-, gamma- and delta-tocopherol also display PLA2 inhibition but consecutively to a lower extent. The grade of inhibition of PLA2 activity by tocopherols correlates well with their biological activity and with their location in the bilayer as shown by fluorescence quenching. Cholesterol does not inhibit PLA2 activity at concentrations even higher than those of tocopherols, indicating that the effect of tocopherols is not due to alteration of membrane fluidity. The possible mechanisms underlying the different behaviour of tocopherol isomers as PLA2 inhibitors are discussed considering its biological significance as membrane stabilizers, suggesting biological actions of compounds with vitamin E activity other than their classical roles as antioxidants.     

In-111 monoclonal antibody versus Ga-67 citrate and Tc-99m SC subtraction in a patient with malignant melanoma

Gallium-67 is routinely used for follow-up of patients with malignant melanoma. However, its nonspecificity for melanoma and its high rate of false-positive results have always been a matter of concern. The authors describe a patient who encountered serious problems with the use of gallium. Because gallium is taken up well by the liver and by melanoma, results of gallium scintigraphy of the liver may appear normal even if there is metastatic disease. In this patient, results of gallium scintigraphy of the liver were negative for metastasis but revealed extrahepatic foci detected by the monoclonal antibody. Computed tomography showed areas of attenuation, revealing only a few intrahepatic tumors and no extrahepatic disease. Tc-99m SC revealed intrahepatic metastases, but no extra-hepatic metastases were seen. A monoclonal antibody (ZME-018) scintigram did reveal hepatic metastases along with probable small, extrahepatic, metastatic foci. Overall hepatic uptake of the monoclonal antibody was relatively low. An image subtraction algorithm was devised whereby the sulfur colloid image was subtracted from the gallium scintigram. The resultant image revealed both the intrahepatic and extrahepatic metastases seen on the ZME-018 images. It is likely that in the past many hepatic metastases have been missed because Tc-99m SC images have not been routinely used as part of melanoma management protocols. The uptake of the ZME-018 by the tumor was significantly higher than that of the normal liver, suggesting that ZME-018 labeled with the appropriate emitter may be an effective specific therapeutic tool in selected patients.     

Genetic and biochemical evidence for a novel avermectin-sensitive chloride channel in Caenorhabditis elegans. Isolation and characterization

Avermectins are a class of macrocyclic lactones that is widely used in crop protection and to treat helminth infections in man and animals. Two complementary DNAs (GluClalpha and GluClbeta) encoding chloride channels that are gated by avermectin and glutamate, respectively, were isolated from Caenorhabditis elegans. To study the role of these subunits in conferring avermectin sensitivity we isolated a mutant C. elegans strain with a Tc1 transposable element insertion that functionally inactivated the GluClalpha gene (GluClalpha::Tc1). GluClalpha::Tc1 animals exhibit a normal phenotype including typical avermectin sensitivity. Xenopus oocytes expressing GluClalpha::Tc1 strain mRNA elicited reduced amplitude avermectin and glutamate-dependent chloride currents. Avermectin binding assays in GluClalpha::Tc1 strain membranes showed the presence of high affinity binding sites, with a reduced Bmax. These experiments suggest that GluClalpha is a target for avermectin and that additional glutamate-gated and avermectin-sensitive chloride channel subunits exist in C. elegans. We isolated a cDNA (GluClalpha2) encoding a chloride channel that shares 75% amino acid identity with GluClalpha. This subunit forms homomeric channels that are gated irreversibly by avermectin and reversibly by glutamate. GluClalpha2 coassembles with GluClbeta to form heteromeric channels that are gated by both ligands. The presence of subunits related to GluClalpha may explain the low level and rarity of target site involvement in resistance to the avermectin class of compounds.     

Bronchopulmonary sequestration with MR angiographic evaluation. A case report

To determine the influence of various oestrogenenic administrations on lipid response, 63 women with total abdominal hysterectomy and bilateral anexectomy were studied before and 6 and 12 months after receiving 17 beta-oestradiol by different means. The effect on the levels of lipids and lipoproteins of the 2 mg/24 h administration of oestradiol valerate was compared with 1.5 mg/day of percutaneous 17 beta-oestradiol and 0.05 mg/day of transdermic oestradiol. The treatments were given continuously over a year. The oestradiol valerate produced a statistically significant increase (P < 0.05) of the HDL-C levels both after 6 and 12 months (10.6% vs. 11.6%). A significant increase was also observed (P < 0.05) in the Apo AI levels during the treatment (18 and 25%). On the other hand, unfavorable side effects with oestradiol were not produced, either percutaneous or transdermic, on lipid plasmatic or lipoprotein levels. These data show the benefit of oral oestrogenic therapy and the maintenance of the lipid profile in percutaneous and transdermic therapies in oophorectomized women.     

Selective decontamination of the digestive tract: effect of cessation of routine application at an ICU

BACKGROUND: Selective decontamination of the digestive tract (SDD) with non-absorbable antibiotics was extensively used at intensive care units (ICU) in Europe to prevent nosocomial infections in critically ill patients. After three recent meta-analyses in which it was demonstrated that SDD did not influence hospital stay and mortality in these patients several ICU's decided to stop the routine use of SDD. OBJECTIVE: To examine the effects of the cessation of SDD on nosocomial infections, mortality and hospital stay at an ICU in post-operative patients. DESIGN: Retro- and prospective follow-up. PATIENTS: Post-operative patients with mechanical ventilation (MV) for > or = 5 days at an ICU were included. The retrospective group (SDD group) comprised of 138 patients (mean age 66, range 10-91; 78% male) and the prospective group (non-SDD group) of 142 patients (mean age 67 range 18-85; 65% male). The SDD regime consisted of colistin, tobramycin and amphotericin B. Cessation of the SDD was accompanied by a shortening of the routine intravenous cefuroxime prophylaxis. RESULTS: There was a nonsignificant increase from an average 21 to 23 days ICU stay in the non-SDD group when compared with the SDD group (p > 0.05). Of the 280 patients 97 (35%) died on the ICU. The risk of death was lower in the non-SDD group (adjusted hazard ratio 0.7 with 95% Cl 0.5-1.1). There was a trend towards an increase in infections as a cause of death in the non-SDD group (38% of the ceased patients versus 20% in the SDD group) (p > 0.05). The incidence of respiratory tract infection (per 1000 person days) was 80 (95% Cl 48-113) in the non-SDD group versus 19 (95% Cl 8-22) in the SDD group (adjusted hazard ratio 4.5 (95% Cl 2.9-7.1)). CONCLUSION: The cessation of the routine application of SDD in post-operative patients mechanically ventilated for 5 days or more did nod adversely affect survival nor increased length of stay at the ICU. There may have been a shift to infections as a cause of death after cessation of SDD.     

The activity and size of the nucleus of comet Hale-Bopp (C/1995 O1) [see comment

Analysis of Hubble Space Telescope (HST) images of comet Hale-Bopp (C/1995 O1) suggests that the effective diameter of the nucleus is between 27 to 42 kilometers, which is at least three times larger than that of comet P/Halley. The International Ultraviolet Explorer and HST spectra showed emissions from OH (a tracer of H2O) and CS (a tracer of CS2) starting in April 1996, and from the CO Cameron system (which primarily traces CO2) starting in June 1996. The variation of the H2O production rate with heliocentric distance was consistent with sublimation of an icy body near its subsolar point. The heliocentric variation in the production rates of CS2 and dust was different from that of H2O, which implies that H2O sublimation did not control the CS2 or dust production during these observations.     

Targeting the receptor-Gq interface to inhibit in vivo pressure overload myocardial hypertrophy

Hormones and neurotransmitters may mediate common responses through receptors that couple to the same class of heterotrimeric guanine nucleotide-binding (G) protein. For example, several receptors that couple to Gq class proteins can induce cardiomyocyte hypertrophy. Class-specific inhibition of Gq-mediated signaling was produced in the hearts of transgenic mice by targeted expression of a carboxyl-terminal peptide of the alpha subunit Galphaq. When pressure overload was surgically induced, the transgenic mice developed significantly less ventricular hypertrophy than control animals. The data demonstrate the role of myocardial Gq in the initiation of myocardial hypertrophy and indicate a possible strategy for preventing pathophysiological signaling by simultaneously blocking multiple receptors coupled to Gq.