Purinoceptor activation of chloride transport in cystic fibrosis and CFTR-transfected pancreatic cell lines

The regulation of chloride efflux from cystic fibrosis pancreatic adenocarcinoma cells (CFPAC-1) and wild-type CFTR-transfected CFPAC-1 cells (TPAC) was compared. Forskolin (10 microM) stimulated chloride efflux from the corrected TPAC cells but not from CFPAC-1 cells. Chloride efflux from both cell types was activated by thapsigargin (0.5 microM). The nucleotides ATP and UTP and the non-hydrolyzable ATP analogue, adenosine 5'-O-(3-thio) triphosphate (ATPgammaS), stimulated chloride efflux from both cell types. None of the other P2 purinoceptor agonists investigated elicited a response. The order of potency was ATP > or = UTP > or = ATPgammaS. Adenosine (10-100 microM) activated choride efflux from the TPAC but not the CFPAC cell line with no increase in intracellular cyclic AMP. Small but statistically significant inhibitions of the adenosine-(50 microM)-stimulated increase in chloride efflux were elicited by the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (CPX, 100 nM) and the A2 receptor antagonist 3,7-dimethyl-1-propylargylxanthine (DMPX, 10 microM). The A2A receptor antagonist 8-(3-chlorostyryl)caffeine (CSC, 100 nM) had no significant effect. These results provide evidence for the regulation of chloride efflux by P2Y2 purinoceptors in genetically-corrected and CF pancreatic cell lines. Studies with adenosine receptor antagonists indicate some possible involvement of A1 and A2 (but not A2A) receptors in the adenosine stimulation of chloride efflux, but the relatively small effects of the inhibitors coupled with lack of increase in cyclic AMP and a response only in the CFTR-transfected cells also suggests a possible direct effect of adenosine on CFTR.     

The impact of antigen density and antibody affinity on antibody-dependent cellular cytotoxicity: relevance for immunotherapy of carcinomas

We studied the sensitivity of human melanoma (Bro strain) xenografts to drugs of the nitrosoalkylurea (NAU) class: nitrosomethylurea (NMM), karmustin (BCNU), nimustin (ACNU), nitrulin, and ADEKO. High antitumor activity of NAM was shown when the drugs were applied not only at the early, but also at the late stages of tumor progression (tumor mass 400 and 1200 mg, respectively). The therapeutic effect of the drugs was estimated with the use of criteria characterizing the kinetics of tumor regression, increased life span, and survival of treated animals. After early administration of the drugs (Day 4 after tumor transplantation), 67% and 50% of animals survive under the influence of nitrulin and ACNU, respectively, while the rate of tumor regression increased in the sequence nitrulin < karmustin < NMM < ACNU. After late administration (11 days after tumor transplantation), NMM was most effective at increasing survival (35% of survived animals by 35 days of observation), while the rate of tumor regression increased in the sequence ADEKO < NMM < karmustin < nitrulin < ACNU.     

Novel diversity in Th1, Th2 type differentiation of hemagglutinin-specific T cell clones elicited by natural influenza virus infection in three major haplotypes (H-2b,d,k)

The serotonin 5-HT3 receptor, a ligand-gated ion channel, has previously been shown to be present on a subpopulation of brain nerve terminals, where, on activation, the 5-HT3 receptors induce Ca2+ influx. Whereas postsynaptic 5-HT3 receptors induce depolarization, being permeant to Na+ and K+, the basis of presynaptic 5-HT3 receptor-induced calcium influx is unknown. Because the small size of isolated brain nerve terminals (synaptosomes) precludes electrophysiological measurements, confocal microscopic imaging has been used to detect calcium influx into them. Application of 100 nM 1-(m-chlorophenyl)biguanide (mCPBG), a highly specific 5-HT3 receptor agonist, induced increases in internal free Ca2+ concentration ([Ca2+]i) and exocytosis in a subset of corpus striatal synaptosomes. mCPBG-induced increases in [Ca2+]i ranged from 1.3 to 1.6 times over basal values and were inhibited by 10 nM tropisetron, a potent and highly specific 5-HT3 receptor antagonist, but were insensitive to the removal of external free Na+ (substituted with N-methyl-D-glucamine), to prior depolarization induced on addition of 20 mM K+, or to voltage-gated Ca2+ channel blockade by 10 microM Co2+/Cd2+ or by 1 microM omega-conotoxin MVIIC/1 microM oemga-conotoxin GVIA/200 nM agatoxin TK. In contrast, the Ca2+ influx induced by 5-HT3 receptor activation in NG108-15 cells by 1 microM mCPBG was substantially reduced by 10 microM Co2+/Cd2+ and was completely blocked by 1 microM nitrendipine, an L-type Ca2+ channel blocker. We conclude that in contrast to the perikaryal 5-HT3 receptors, presynaptic 5-HT3 receptors appear to be uniquely calcium-permeant.     

Opinions of disease management programs among medical directors of managed care organizations

Anastomotic infection is an uncommon but potentially life-threatening complication after lung transplantation. We recently encountered three lung transplant recipients with invasive candidal anastomotic infection. Two patients were admitted with dyspnea and fever, and one asymptomatic infection was detected on surveillance bronchoscopy. All three patients were treated similarly with a combination of intravenous amphotericin B, inhaled amphotericin B, and oral fluconazole. The combination of systemic and inhaled antifungal agents successfully treated all three cases of anastomotic infection.     

Oesophagostomum spp. in pigs: resistance to reinfection

For a study on the occurrence of resistance to reinfection with porcine nodular worm species, pigs were infected twice weekly with 1,000 infective larvae (L3) of Oesophagostomum quadrispinulatum for 8 weeks. All pigs, including noninfected controls, were then treated with fenbendazole. At 10 days after treatment, all pigs received a single challenge inoculation of 5,000 L3 of either O. dentatum or O. quadrispinulatum, respectively. Pigs were slaughtered at 6 weeks after the challenge infection for determination of their worm burdens. The pigs trickle- and challenge-infected with O. quadrispinulatum had significantly lower egg excretion levels (P < 0.01) and worm burdens (P < 0.05) than challenge control pigs, thus indicating some degree of host immunity against the homologous challenge infection. No resistance to reinfection was evident for the heterologous challenge infection. This study elucidates further aspects of the interaction between nodular worm species in the pig.     

Effect of HIV infection on the natural history of anal human papillomavirus infection

OBJECTIVE: To identify risk factors for the detection of prevalent and incident anal human papillomavirus (HPV) infection, and HPV persistence among HIV-seropositive and seronegative homosexual men. DESIGN: Longitudinal study of 287 HIV-seronegative and 322 HIV-seropositive men attending a community-based clinic. METHODS: Subjects underwent an interview and examination; specimens were collected for HIV serology and assessment of anal HPV and HIV DNA. RESULTS: Anal HPV DNA was detected at study entry in 91.6% of HIV-infected men, and 65.9% of men not infected with HIV. HPV detection was associated with lifetime number of sexual partners and recent receptive anal intercourse (HIV-seronegative men), decreased CD4+ lymphocyte count (HIV-seropositive men), and anal warts (all men). Among men negative for HPV at study entry, subsequent detection of HPV was associated with HIV, unprotected receptive anal intercourse, and any sexual contact since the last visit. Among men positive for HPV at study entry, subsequent detection of additional HPV types was more common among HIV-seropositive men. Becoming HPV negative during follow-up was less common among men with HIV or high HPV levels at study entry. Among those with HIV, HPV persistence was associated with presence of anal HIV DNA, but not with CD4+ lymphocyte count. CONCLUSIONS: Risk of anal HPV infection appears to increase with sexual exposure, epithelial trauma, HIV infection and immune deficiency. Incident infection may result from recent sexual exposure or reactivation of latent infection. Further studies are needed to elucidate the mechanism by which HIV DNA in the anal canal increases the risk of HPV persistence.     

Effects of prior exercise on exercise-induced arterial hypoxemia in young women

Insulin-like growth factor binding proteins (IGFBP) proteases have been proposed to be involved in changes of serum IGFBP pattern during pregnancy. IGFBP-4 and -5 are degraded specifically by proteases in pregnancy serum in vitro, whereas IGFBP-3 proteolytic activity was also detected in nonpregnancy serum. To identify and characterize IGFBP proteases, human pregnancy serum was fractionated by size exclusion chromatography revealing IGFBP-4 protease activities in fractions coeluting with proteins of approximately 600-kDa and 50- to 100-kDa molecular mass. In both fractions, a predominant 50-kDa gelatinase was found, suggesting that parts of the gelatinase activity might aggregate or are complexed with other proteins forming a higher molecular complex. Hydroxyapatite chromatography and chromatofocusing of the 50- to 100-kDa serum fraction showed that the IGFBP-4 protease and the 50-kDa gelatinase activity were copurified. When the 50-kDa gelatinase-containing band was excised from the polyacrylamide gel, it exhibited IGFBP-4 proteolytic activity, resulting in the formation of 17- and 10-kDa fragments. [125I] IGFBP substrate zymography combined with fragment blotting showed that the 1,10-phenanthroline-sensitive 50-kDa protease activity purified by chromatofocusing also cleaved IGFBP-3 and -5. Other proteases detected in pregnancy serum fractions with Mr estimates of 79-, 30-, and 22-kDa degraded IGFBP-3 and -5 but not IGFBP-4. [125I] IGFBP-5 substrate zymography revealed that the 30-kDa IGFBP protease was inhibited by serine protease inhibitors. Whereas 1,10-phenanthroline inhibited the IGFBP proteolytic activity in the solution assay, serine protease inhibitors failed to affect proteolysis, indicating the predominant contribution of the metalloproteinase to IGFBP proteolysis. Tissue inhibitors of matrix metalloproteinases-1 and -2 revealed weak or no inhibition of IGFBP-4 and -5 proteolytic activity, whereas a hydroxamic acid-based inhibitor, potentially inhibiting disintegrin metalloproteases, completely prevented the proteolysis of IGFBPs. Whereas no specific immunoreactivity of the 50-kDa protein with antimatrix metalloproteinase-1, -2, -3, -9, or -13 antibodies was observed, antidisintegrin domain-specific antibodies bound to the 50-kDa gelatinase. These studies provide the first direct biochemical evidence that human pregnancy serum contains a 50-kDa IGFBP protease with properties of a soluble disintegrin metalloproteinase that appears to be potentially involved in regulating IGF bioavailability for placental and fetal growth.     

Bone marrow composition and bone microarchitecture and turnover in blacks and whites

We examined the relationship between bone histomorphometric variables versus marrow cellularity, marrow adiposity (among hemopoietic cells), and fatty degeneration (areas of only fat) of bone marrow in iliac crest bone samples from 98 normal black (n = 53) and white (n = 45) males and females. We found blacks to have greater marrow cellularity (p = 0.0001), less marrow adiposity (among hemopoietic cells, p = 0.0001), greater values for bone volume (p = 0.030), trabecular thickness (p = 0.002), and static bone turnover variables (osteoid volume, p = 0.001; osteoid surface, p = 0.001; osteoid thickness, p = 0.001; eroded surface, p = 0.0006) than whites. Marrow cellularity correlated positively with static bone turnover variables osteoid volume (r = 0.257, p = 0.011), osteoid surface (r = 0.265, p = 0.008), osteoid thickness (r = 0.217, p = 0.032), and eroded surface (r = 0.273, p = 0.007) when all 98 cases were analyzed together. These findings suggest that marrow cells may influence bone turnover. The extent of fatty degeneration, but not that of adipose tissue, increased with age in blacks (r = 0.476, p = 0.0003) and whites (r = 0.476, p = 0.001), as did bone loss. There was no racial difference in the extent of fatty degeneration. We conclude that the lesser extent of adiposity in blacks is a racial characteristic that is unaffected by aging, whereas fatty degeneration which may have partly occupied space vacated by bone loss, is an aging phenomenon, unrelated to race. Greater bone turnover in blacks may be expected to lead to more frequent renewal of fatigue-damaged bone, which together with sturdier bone structure may contribute to the lower fragility fracture rates in blacks.     

Comparison of 51Cr-EDTA with 99m-Tc-DTPA slope clearance for estimation of glomerular filtration rate using the one compartment model

AIM: Of this study is to determine the relationship between 51Cr-EDTA and 99mTc-DTPA slope clearance applying the "one-compartment model". METHODS: The "one-compartment model" was chosen to calculate and to compare the glomerular filtration rates of 25 patients with normal and pathological creatinin values after injection of 51Cr-EDTA and 99mTc-DTPA simultaneously. RESULTS: The two clearance values correlated well (r = 0.996), and the 99mTc-DTPA clearance was systematically higher (28%). The 99mTc-DTPA was calculated and compared after taking three plasma samples. Taking two samples, only minor differences were seen and the correlation was high (r = 0.992). CONCLUSION: The results of this study encouraged us to adopt the use of 99mTc-DTPA instead of 51Cr-EDTA in determining the glomerular filtration applying the "one-compartment model" in slope with two plasma samples.     

The life span of silicone gel breast implants and a comparison of mammography, ultrasonography, and magnetic resonance imaging in detecting implant rupture: a meta-analysis

Because of the growing concern surrounding the integrity and life span of silicone gel breast implants and the reported variations in the diagnostic accuracy of various imaging techniques in identifying ruptured implants, the authors undertook a meta-analysis of articles in the scientific literature to examine these concerns. They were able to include reports from the literature that detailed the condition and removal of 1,099 breast implants during the past 7 years. The median life span of a silicone gel implant was estimated to be 16.4 years. Of the implants, 79.1% were intact at 10 years, falling to 48.7% by 15 years. The sensitivities and specificities of three imaging modalities used in the diagnosis of implant rupture (mammography, ultrasonography, and magnetic resonance imaging [MRI]) were also evaluated and compared statistically in an effort to discover which of the three techniques might serve as the most reliable screening tool in the diagnosis of gel implant rupture. The sensitivity of mammography for finding a ruptured implant is 28.4% with a specificity of 92.9%. Ultrasonography has a sensitivity and specificity of 59.0% and 76.8% respectively compared with MRI, which was 78.1% and 80.0% respectively. For implants in place for 10 years, one would need to image 3.3 implants by ultrasound to identify a single possible rupture. However, because of the 76.8% specificity, 8.1 implants would need to be imaged to find a confirmed intraoperative rupture. This was similar to MRI, in which 3.1 implants would need to be imaged to detect one suspected rupture, and 6.1 implants would need to be imaged to find one intraoperatively confirmed rupture. The authors do not recommend either ultrasound or MRI as a screening tool based on their meta-analysis.