Evaluation of argyrophilic nucleolar organizer regions (AgNORs) in oral carcinomas in relation to human papillomavirus infection and cytokinetics

The numbers of argyrophilic nucleolar organizer regions (AgNORs) were quantified in oral carcinomas (n = 39) with or without human papillomavirus (HPV) infection. The AgNOR counts of the HPV-positive samples (7.15 +/- 2.13) were not significantly (P = 0.09) higher than those of the HPV-negative ones (6.16 +/- 1.89). Furthermore, the lesions infected with multiple HPV types had greater counts than those with HPV type 16/18 infection alone. Significant differences were observed between the mean counts of the poorly (10.50 +/- 0.54), moderately (7.31 +/- 1.07) and well- (5.12 +/- 0.85) differentiated carcinomas. The mean AgNOR numbers in the oral carcinomas at TNM stages III/IV were found to be significantly (P < 0.01) higher than the numbers in corresponding stage II lesions. Cytokinetics of the lesions assessed by the bromodeoxyuridine (Brdu) labelling index (LI%) showed a linear correlation (r = 0.91; P < 0.0001) with their respective mean AgNOR counts.     

Turnover of inositol polyphosphate pyrophosphates in pancreatoma cells

There is little information concerning the intracellular function of inositol 1,3,4,5,6-pentakis- and hexakisphosphate, despite their being the most abundant inositol polyphosphates. Current opinions that they play passive roles as antioxidants (Graf, E., Mahoney, J. R., Bryant, R. G., and Eaton, J. W. (1987) J. Biol. Chem. 259, 3620-3624) or "housekeeping" molecules (Berridge, M. J., and Irvine, R. F. (1989) Nature 341, 197-205) arises from belief in their metabolic lethargy. However, we have discovered that cell homogenates, incubated with 5 mM fluoride and 5 mM ATP, converted both inositol hexakisphosphate (Km = 2 +/- 0.5 microM, Vmax = 9 +/- 2 pmol/mg of protein/min) and inositol 1,3,4,5,6-pentakisphosphate (Km = 13 +/- 4 microM, Vmax = 11 +/- 5 pmol/mg of protein/min) to more polar products. These reactions were also observed in intact cells treated with 0.5-20 mM fluoride, and the precursor/product relationships were confirmed by comparing the effects of fluoride on cells differentially labeled with [3H]inositol in either short-term or pulse-chase protocols. The novel products were determined to be inositol pyrophosphates because of their relatively specific hydrolysis by tobacco pyrophosphatase and alkaline phosphatase. The pyrophosphates were metabolized rapidly by cell homogenates back to their pentakisphosphate and hexakisphosphate precursors. This endogenous pyrophosphatase activity was inhibited by up to 99% by 5 mM fluoride in vitro. In intact cells incubated with 10 mM fluoride, about 20% of the inositol 1,3,4,5,6-pentakisphosphate pool, and 50% of the inositol hexakisphosphate pool were each converted to pyrophosphate derivatives within 1 h.     

Chromosome 9p deletions in invasive and noninvasive nonfunctional pituitary adenomas: the deleted region involves markers outside of the MTS1 and MTS2 genes

We have screened 57 cases of primary, nonfunctional, pituitary adenomas for loss of heterozygosity of markers on chromosome 9p. Using a panel of 11 microsatellite markers, we found hemizygous deletion with at least one of the markers in 18 tumors (31.5%). The frequency of loss was similar in both noninvasive (8 of 26; 31%) and invasive tumors (10 of 31; 32%), suggesting that loss on this chromosome might be an early event in pituitary tumorigenesis. Two discrete areas of loss were punctuated by a region of retention of heterozygosity between the markers D9S171 and IFNA, indicative of homozygous deletion. However, multiplex PCR analysis (MTS1 and MTS2) and the presence of a 3' untranslated region polymorphism in MTS1 suggested that neither of these tumor suppressor genes was homozygously deleted. In 6 of the 18 tumors showing LOH, sufficient DNA was also available for Southern blot analysis and, in all cases, showed retention of MTS1. Cell mixing experiments of tumor cell DNA homozygously deleted for MTS1 with DNA in which neither copy of the gene was deleted only gave rise to a signal at contamination levels greater than 30% and could discriminate homozygous and hemizygous loss. These studies support the recent findings that mechanisms other than hemi- and homozygous deletion are most likely responsible for the loss of MTS1 gene product in pituitary tumors (M. Woloschak et al., Cancer Res., 56: 2493-2486, 1996.). These data show that losses on either side of 9p21-22, both or either of which may be deleted, are involved in pituitary tumorigenesis and provide evidence for distinct suppressor gene loci, in addition to MTS1, on chromosome 9p.     

Activation of large-conductance potassium channels in pregnant human myometrium by pinacidil

OBJECTIVE: The aim was to investigate the effects of the potassium-channel opener pinacidil on single uterine potassium channels and the contribution of the latter to pinacidil-induced myometrial relaxation. STUDY DESIGN: Myometrial strips and freshly dispersed uterine myocytes were prepared from the myometrial biopsy samples of women undergoing elective, nonlabor caesarean section at term gestation. RESULTS: In isometric tension experiments pinacidil potently relaxed pregnant nonlabor human myometrial strips, with an agonist concentration yielding the half maximal response of 0.4 +/- 0.1 micromol/L. This effect was antagonized by 500 nmol/L charybdotoxin. Application of 10 micromol/L glibenclamide also inhibited the pinacidil-induced relaxation. Coapplication of charybdotoxin (500 nmol/L) and glibenclamide (10 micromol/L) produced a biphasic curve, which was fitted to a two-site model with values for agonist concentration yielding the half maximal response of 0.6 +/- 0.2 micromol/L and 189.7 +/- 0.8 micromol/L. Large-conductance calcium-dependent potassium channel activity was dramatically increased after application of pinacidil (between 10 and 100 micromol/L) to both inside-out and outside-out patches. The activation required the presence of calcium ions at the intracellular aspect of the membrane. Charybdotoxin but not glibenclamide blocked pinacidil-induced unitary large-conductance calcium-dependent potassium channel activity. CONCLUSION: Pinacidil-mediated relaxation of human pregnant myometrial strips may be partially attributable to the opening of uterine large-conductance calcium-dependent potassium channels in addition to adenosine triphosphate potassium channel activation. Drugs with specific potassium channel-activating properties may have important clinical application as novel tocolytics in the treatment of preterm labor.     

The infrared dichroism of transmembrane helical polypeptides

Polarized attenuated total internal reflectance techniques were applied to study the infrared dichroism of the amide I transition moment in two membrane-bound peptides that are known to form oriented transmembrane helices: gramicidin A in a supported phospholipid monolayer and Ac-Lys2-Leu24-Lys2-amide (L24) in oriented multibilayers. These studies were performed to test the ability of these techniques to determine the orientation of these peptides, to verify the value of optical parameters used to calculate electric field strengths, to examine the common assumptions regarding the amide I transition moment orientation, and to ascertain the effect of surface imperfections on molecular disorder. The two peptides exhibit marked differences in the shape and frequency of their amide I absorption bands. Yet both peptides are highly ordered and oriented with their helical axes perpendicular to the membrane surface. In the alpha-helix formed by L24, there is evidence for a mode with type E1 symmetry contributing to amide I, and the amide I transition moment must be more closely aligned with the peptide C=O (< 34 degrees) than earlier studies have suggested. These results indicate that long-standing assumptions about the orientation of amide I in a peptide require some revision, but that in general, infrared spectroscopy yields reliable information about the orientation of membrane-bound helical peptides.     

Agreement between rectal and tympanic membrane temperatures in marathon runners

STUDY OBJECTIVE: To determine the agreement between rectal temperature and infrared tympanic membrane temperatures in marathon runners presenting to a field hospital at the finish line. METHODS: The subjects of this prospective, blinded, controlled study were runners 18 years or older who were triaged to the acute care medical area at the finish line for suspected hypothermia, hyperthermia, dehydration, or altered mental status. Rectal and tympanic temperatures were measured simultaneously in all subjects for whom rectal temperature measurement had been deemed necessary and recorded on separate data cards. RESULTS: Of the 239 runners treated in the acute care medical area, 37 required rectal temperature measurement and were enrolled in the study. The mean rectal temperature was 38.45 degrees +/- 1.20 degrees C (range, 35.9 degrees to 41.5 degrees C). The mean tympanic membrane temperature was 37.81 degrees +/- 95 degrees C (range, 36.3 degrees to 40.4 degrees C). Pearson's correlation coefficient revealed a moderate correlation (r = .6902, P = .00023). The mean temperature difference between the two thermometers, mean rectal minus mean tympanic membrane, was .64 degrees C (95% confidence interval, .35 degrees to .93 degrees C). Sixty-Two percent of the tympanic membrane readings were within 1 degree C of their rectal counterparts. Agreement ranged from 1.16 degrees (+2 SD) to -2.95 degrees (-2 SD). The 95% confidence interval was 1.67 degrees to -2.95 degrees C. CONCLUSION: We were able to demonstrate only a moderate correlation between the two thermometer readings, with a wide spread between the limits of agreement. This spread could be clinically significant and therefore limits the usefulness of tympanic temperature in the marathon race setting. Because of the potentially large and clinically significant differences in rectal and tympanic temperatures and the limitations inherent in our study, we cannot endorse the use of tympanic temperature in the setting of a marathon event.     

Biphasic insulin secretion during intravenous glucose tolerance test promotes optimal interstitial insulin profile

We examined the hindlimb lymph insulin profile during simulated intravenous glucose tolerance tests (IVGTTs) in anesthetized dogs to test the following hypotheses: 1) the biphasic insulin response to intravenous glucose can be seen as a priming bolus and a secondary infusion that effect a rapid stepwise increase in the interstitial insulin concentration and 2) the activation of glucose utilization (rate of glucose uptake [Rd]) during an IVGTT is more similar to the dynamics of the interstitial insulin profile than that of the arterial plasma. Three insulin profiles were infused: a normal biphasic pattern, a second phase infusion only, and a biphasic pattern with a fourfold greater first phase and a normal second phase. During the normal biphasic infusion, lymph insulin quickly reached and maintained a steady-state concentration (10 min, 26.42 +/- 0.86 microU/ml). With second phase only, it took lymph insulin 35 min to reach a steady state of lower concentration (13.13 +/- 0.46 microU/ml) than the normal. And with a fourfold greater first phase, lymph insulin plateaued quickly (16 min, 140.87 +/- 1.68 microU/ml), but for a shorter duration than the normal. For each profile, the time course of activation of Rd did not follow the time course of insulin in the plasma, but was more similar to that of insulin in the interstitial fluid. These results show that the biphasic response allows interstitial insulin to rapidly reach and maintain a steady state beneficial to activation and maintenance of glucose utilization.     

Propionyl-L-carnitine

Propionyl-L-carnitine stimulates energy production in ischaemic muscles by increasing citric acid cycle flux and stimulating pyruvate dehydrogenase activity. The free radical scavenging activity of the drug may also be beneficial. Propionyl-L-carnitine improves coagulative fibrinolytic homeostasis in vasal endothelium and positively affects blood viscosity. Improvements in maximum walking distance (MWD) correlated positively with increased mitochondrial oxidative adenosine triphosphate (ATP) synthesis in a study in patients with peripheral arterial disease. Oral propionyl-L-carnitine 1 to 3 g/day significantly improved mean MWD compared with placebo in patients with peripheral arterial obstructive disease (Fontaine Leriche stage II) in double-blind multicentre phase III studies (mean improvements ranged from 21 to 50% with placebo and from 33 to 73% with propionyl-L-carnitine). In one phase III study, propionyl-L-carnitine 1 to 3 g/day significantly improved mean MWD (measured by treadmill) compared with placebo (by 73 vs 46% after 24 weeks) in patients with intermittent claudication. Oral propionyl-L-carnitine therapy was associated with significant improvements in quality of life compared with placebo in patients with a baseline MWD < 250m. Propionyl-L-carnitine appears to be well tolerated, showing a similar incidence of adverse events to that reported in placebo recipients.