Millimeter/sub-mm spectroscopy of the CrBr radical in the high spin X6Σ+ state.

The millimeter/submillimeter spectrum of the CrBr radical has been recorded in the frequency range of 220-300 GHz using direct absorption techniques, utilizing a new instrumental design. This study is the first spectroscopic investigation of this radical species by any method. CrBr was synthesized in a DC discharge by the reaction of chromium vapor, produced in a Broida-type oven, with Br2CH2 in argon. Six to nine rotational transitions were measured for four isotopologues of this molecule in their natural abundances, 52Cr79Br, 52Cr81Br, 53Cr79Br, and 53Cr81Br. Each transition was found to consist of six distinct fine structure components, indicating a 6Σ+ ground electronic state, as observed for CrF and CrCl. Lines originating in the v = 1 and 2 vibrational states were recorded for 52Cr79Br and 52Cr81Br as well. The spectra were analyzed using a Hund's case (b) Hamiltonian, and rotational, spin-spin, and spin-rotation parameters were determined. The third-order spin-rotation constant γs and the fourth order spin-spin term θ were necessary for the analysis; these parameters are thought to play a role in states with high multiplicities. Equilibrium parameters were also derived for the CrBr; a bond length of re = 2.337 282 (30) Å and a vibrational constant of ωe ≅ 300 cm-1 were determined. The sign and magnitude of the spin-spin and spin-rotation constants suggest the presence of nearby 4Π and 6Π excited states in CrBr, lying ∼9000 cm-1 above the ground state. The new instrument design, employing more compact, free-space optics utilizing an offset ellipsoidal mirror, facilitated these measurements.

Flash glucose monitoring for the safe use of a 2-day intermittent energy restriction in patients with type 2 diabetes at risk of hypoglycaemia: An exploratory study.

AIMS: Two medication change protocols were tested, both based on haemoglobin A1c (HbA1c), with one protocol also accounting for hypoglycaemic events. The aim was to compare the two protocols during intermittent energy restriction (5:2 diet). METHODS: Forty-two adults with type 2 diabetes (HbA1c ≥ 7% [53 mmol/mol], BMI of ≥27 kg/m2) treated with sulphonylureas and/or insulin were recruited and randomised 1:1 to fixed or adjusted medication protocols. Participants experiencing hypoglycaemia during a 2-week usual diet period then followed the 5:2 diet for 2 weeks (2 non-consecutive very-low-calorie days [500-600 kcal] and 5 habitual eating days/week), following the allocated medication protocol. The primary outcome was to determine if the adjusted protocol was superior to the fixed protocol at reducing hypoglycaemic events during the 5:2 diet. Flash glucose monitoring was used throughout to detect hypoglycaemia. RESULTS: There was a significant difference in change in the number of hypoglycaemic events between fixed and adjusted protocols (-1.0 vs. -3.5; P = 0.04). Over 60% of participants on the adjusted protocol had no hypoglycaemic events. CONCLUSIONS: This pilot study demonstrates the importance of assessing the risk of hypoglycaemia before starting a 5:2 diet and that the adjusted medication protocol is likely the best option for patients at risk. CLINICAL TRIAL REGISTRY: This study has been registered with the Australia New Zealand Clinical Trial Registry (ANZCTR) www.anzctr.org.au and given the registration number ACTRN12617000512325.

Risk factors for lung cancer and for intervention effects in CARET, the Beta-Carotene and Retinol Efficacy Trial.

BACKGROUND: Evidence has accumulated from observational studies that people eating more fruits and vegetables, which are rich in beta-carotene (a violet to yellow plant pigment that acts as an antioxidant and can be converted to vitamin A by enzymes in the intestinal wall and liver) and retinol (an alcohol chemical form of vitamin A), and people having higher serum beta-carotene concentrations had lower rates of lung cancer. The Beta-Carotene and Retinol Efficacy Trial (CARET) tested the combination of 30 mg beta-carotene and 25,000 IU retinyl palmitate (vitamin A) taken daily against placebo in 18314 men and women at high risk of developing lung cancer. The CARET intervention was stopped 21 months early because of clear evidence of no benefit and substantial evidence of possible harm; there were 28% more lung cancers and 17% more deaths in the active intervention group (active = the daily combination of 30 mg beta-carotene and 25,000 IU retinyl palmitate). Promptly after the January 18, 1996, announcement that the CARET active intervention had been stopped, we published preliminary findings from CARET regarding cancer, heart disease, and total mortality. PURPOSE: We present for the first time results based on the pre-specified analytic method, details about risk factors for lung cancer, and analyses of subgroups and of factors that possibly influence response to the intervention. METHODS: CARET was a randomized, double-blinded, placebo-controlled chemoprevention trial, initiated with a pilot phase and then expanded 10-fold at six study centers. Cigarette smoking history and status and alcohol intake were assessed through participant self-report. Serum was collected from the participants at base line and periodically after randomization and was analyzed for beta-carotene concentration. An Endpoints Review Committee evaluated endpoint reports, including pathologic review of tissue specimens. The primary analysis is a stratified logrank test for intervention arm differences in lung cancer incidence, with weighting linearly to hypothesized full effect at 24 months after randomization. Relative risks (RRs) were estimated by use of Cox regression models; tests were performed for quantitative and qualitative interactions between the intervention and smoking status or alcohol intake. O'Brien-Fleming boundaries were used for stopping criteria at interim analyses. Statistical significance was set at the .05 alpha value, and all P values were derived from two-sided statistical tests. RESULTS: According to CARET's pre-specified analysis, there was an RR of 1.36 (95% confidence interval [CI] = 1.07-1.73; P = .01) for weighted lung cancer incidence for the active intervention group compared with the placebo group, and RR = 1.59 (95% CI = 1.13-2.23; P = .01) for weighted lung cancer mortality. All subgroups, except former smokers, had a point estimate of RR of 1.10 or greater for lung cancer. There are suggestions of associations of the excess lung cancer incidence with the highest quartile of alcohol intake (RR = 1.99; 95% CI = 1.28-3.09; test for heterogeneity of RR among quartiles of alcohol intake has P = .01, unadjusted for multiple comparisons) and with large-cell histology (RR = 1.89; 95% CI = 1.09-3.26; test for heterogeneity among histologic categories has P = .35), but not with base-line serum beta-carotene concentrations. CONCLUSIONS: CARET participants receiving the combination of beta-carotene and vitamin A had no chemopreventive benefit and had excess lung cancer incidence and mortality. The results are highly consistent with those found for beta-carotene in the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study in 29133 male smokers in Finland.

Transglutaminase activity in human colorectal carcinomas of differing metastatic potential.

Transglutaminase (TGA) activity in four human colorectal carcinoma cell lines of differing metastatic potential, and the effects of mild proteolysis on this activity, was investigated. Rank order of metastatic activity measured in nude mice (intrasplenic injection) was found to be LS174T greater than SW620 greater than WiDr greater than SW480. Rank orders of TGA activity were SW480 greater than WiDr greater than SW620 greater than LS174T. Proteolysis of cell lysates increased LS174T TGA activity 42-fold, SW620 2-fold without affecting WiDr or SW480 activity. Hence a negative association exists between metastatic potential and TGA activity in human colorectal carcinoma cells. Furthermore, a positive association exists between proteolytic activation of TGA and metastatic potential.

Elevated urine uranium excretion by soldiers with retained uranium shrapnel.

The use of depleted uranium in munitions has given rise to a new exposure route for this chemically and radioactively hazardous metal. A cohort of U.S. soldiers wounded while on or in vehicles struck by depleted uranium penetrators during the Persian Gulf War was identified. Thirty-three members of this cohort were clinically evaluated, with particular attention to renal abnormalities, approximately 3 y after their injury. The presence of retained shrapnel was identified by x ray, and urine uranium concentrations were measured on two occasions. The absorption of uranium from embedded shrapnel was strongly suggested by measurements of urine uranium excretion at two time intervals: one in 1993/1994 and one in 1995. Mean urine uranium excretion was significantly higher in soldiers with retained shrapnel compared to those without shrapnel at both time points (4.47 vs. 0.03 microg g(-1) creatinine in 1993/1994 and 6.40 vs. 0.01 microg g(-1) creatinine in 1995, respectively). Urine uranium concentrations measured in 1995 were consistent with those measured in 1994/1993, with a correlation coefficient of 0.9. Spot urine measurements of uranium excretion were also well correlated with 24-h urine collections (r = 0.95), indicating that spot urine samples can be reliably used to monitor depleted uranium excretion in the surveillance program for this cohort of soldiers. The presence of uranium in the urine can be used to determine the rate at which embedded depleted uranium fragments are releasing biologically active uranium ions. No evidence of a relationship between urine uranium excretion and renal function could be demonstrated. Evaluation of this cohort continues.

Determinants of elevated blood lead levels among working men in Greater Beirut.

This cross-sectional study reports the blood lead levels (BLL) among different working groups in Beirut and identifies the risk factors associated with elevated BLLs. A total of 579 men of 18 years of age or older (response rate 96%) working in Greater Beirut were interviewed. Of those, 315 (54.4%) provided a blood sample of which 291 were analyzed for lead. The mean BLL of the 134 men working in white-collar jobs (offices, retail shops) was 12.7 microg/dl (SD 3.7); statistically significantly lower than the mean BLL (18.4 microg/dl; SD 9.8) of the 157 men working in blue-collar occupations (such as gas station attendants, painters, mechanics). A blood lead level of 15 microg/dl or more was associated with blue-collar jobs, number of cigarettes smoked, commuting > or = 3 km to work, years in current occupation, and younger age. A BLL of at least 20 microg/dl was associated with eating lunch at work, in addition to blue-collar jobs, smoking, commuting, years of work, and younger age. The study findings suggest that environmental exposure (those not otherwise exposed to occupational lead) is mainly determined by smoking and exposure to leaded gasoline (commuting). Occupational exposure to lead is prevalent among a wide spectrum of Lebanese workers. Physicians are called upon to inquire more about the potential for lead exposure, especially among blue-collar workers. A policy action to improve working conditions and to phase out the use of leaded gasoline is recommended.

Membrane transporters in drug development.

Membrane transporters have wide, but specific tissue distributions. They can impact on multiple endogenous and xenobiotic processes. Knowledge and awareness within the pharmaceutical industry of their impact on drug absorption, distribution, metabolism and elimination (ADME) and drug safety is growing rapidly. Clinically important transporter-mediated drug-drug interactions (DDIs) have been observed. Up to nine diverse transporters are implicated in the DDIs of a number of widely prescribed drugs, posing a significant challenge to the pharmaceutical industry. There is a complex interplay between multiple transporters and/or enzymes in the ADME and pharmacogenomics of drugs. Integrating these different mechanisms to understand their relative contributions to ADME is a key challenge. Many different factors complicate the study of membrane transporters in drug development. These include a lack of specific substrates and inhibitors, non-standard in vitro tools, and competing/complementary mechanisms (e.g. passive permeability and metabolism). Discovering and contextualizing the contribution of membrane transporters to drug toxicity is a significant new challenge. Drug interactions with key membrane transporters are routinely assessed for central nervous system (CNS) drug discovery therapies, but are not generally considered across the wider drug discovery. But, there is interest in utilizing membrane transporters as drug delivery agents. Computational modeling approaches, notably physiology-based/pharmacokinetic (PB/PK) modeling are increasingly applied to transporter interactions, and permit integration of multiple ADME mechanisms. Because of the range of tissues and transporters of interest, robust transporter, in vitro to in vivo, scaling factors are required. Empirical factors have been applied, but absolute protein quantitation will probably be required.

Classical syndromes in occupational medicine: dimethylaminopropionitrile.

Dimethylaminopropionitrile, used as a catalyst in the manufacture of polyurethane, was responsible for two epidemics of urinary retention, sexual dysfunction, and peripheral neuropathy in 1978. Most affected workers recovered promptly, but some have had persisting neuropathy, sexual and bladder dysfunction, and CNS symptoms. The mechanism of neurotoxicity appears to be interference with axoplasmic transport. The catalyst that caused the problem was withdrawn from the market after swift governmental action.

Occupational lead poisoning: who should conduct surveillance and training?

This commentary challenges the current employer-controlled model for delivering occupational health services. Problems emanating from traditional employer-based medical surveillance and worker education programs for occupational lead poisoning are identified. A new public health model for delivering these services is proposed. This model utilizes a case-based and hazard-based method for bringing workplaces and employers into the program and features direct delivery of surveillance and training services by public health agencies.

Cytotoxicity of heavy metals in the human small intestinal epithelial cell line I-407: the role of glutathione.

Cytotoxicities of metal salts were determined in the intestinal epithelial cell line I-407 in microwell culture plates over 48 h using the widely utilized and accepted neutral red uptake procedure. Rank order cytotoxicities induced by the metal salts (in terms of LC50 values) were found to be HgCl2 (32 microM) > CdCl2 (53 microM) > CuCl2 (156 microM) > T12SO4 (377 microM) > Pb(NO3)2 (1.99 mM). Combined administration of the two most toxic metals at their LC50's showed that their toxicities were not additive or synergistic. The role of glutathione in determining toxicity induced by the metal salts in these cells was assessed by inhibition of its synthesis. Buthionine sulfoximine pretreatment at 1 mM, which was not toxic to the cells, caused sustained reduction in cellular glutathione content (to 13.8% after 48 h) and increased toxicities induced by HgCl2 (5.7-fold) and CuCl2 (1.44-fold) as shown by reductions in the LC50 values. Toxicity induced by the other metals remained unaffected. Administration of glutathione with either HgCl2 or CdCl2 did not protect the cells against their toxicity, and in the case of cadmium its toxicity was exacerbated. N-Acetylcysteine diminished toxicity induced by mercury but not cadmium.

Does cimetidine improve prospects for cancer patients?. A reappraisal of the evidence to date.

BACKGROUND: Evidence first appeared in 1988 that cimetidine as an adjuvant may improve the survival of severely ill gastro-intestinal cancer patients when given peri- or postoperatively. Since then, several studies have appeared which suggest an anticancer activity for cimetidine, although few attempts have been made to corroborate their findings in large, placebo-controlled, double-blind studies. METHOD: We reviewed the literature concerning cimetidine's potential anticancer activity, particularly with regard to gastro-intestinal cancers. RESULTS: Most studies suggest that cimetidine may improve the outcome in cancer patients by a three-pronged mechanism involving (1) inhibition of cancer cell proliferation; (2) stimulation of the lymphocyte activity by inhibition of T cell suppressor function, and (3) inhibition of histamine's activity as a growth factor in tumours. CONCLUSION: Bearing in mind the experimental evidence, as well as the potential and excellent safety profile of cimetidine, more studies are required and justified to clarify cimetidine's protherapeutic activity.

An epidemic of urinary retention caused by dimethylaminopropionitrile.

An epidemic of urinary retention among workers in a polyurethane manufacturing plant was discovered in the spring of 1978. The most severely affected workers had neurogenic bladders confirmed by cystometrograms and mild sensory peripheral neuropathy. A survey of the plant disclosed increased incidence of urinary retention, muscle weakness, paresthesia, insomnia, and sexual dysfunction in exposed workers. A catalyst containing dimethylaminopropionitrile was identified as the probable causative agent, and after its removal no new cases occurred.

Chromatographic measurement of mucin production in cultures of gastric mucous cells.

The use of a miniature column chromatographic assay (using Sepharose CL-4B columns) for measuring mucin production in guinea pig gastric mucous cell cultures is described. The assay was based upon the ability of radiolabelled precursors ([14C]serine and [3H]galactose) to incorporate with high specificity into mucins which thereby appeared in the excluded material. Rates of excluded material radiolabelling by both precursors were constant for incubations up to 24 hours, and substantially reduced by cycloheximide co-incubation (25 microM). Labelled excluded material was completely degraded by mild alkaline borohydride treatment, only partially degraded by HNO2 (pH 1.5), and not degraded by chondroitinase ABC. Thus the major radiolabelled product measured in this system was mucin, although we found that it was less glycosylated than gastric mucins obtained from other sources. In addition, the technique employed to separate and measure mucin production proved rapid and consistent.

Shortened forms of provocative lead chelation.

Shortened urinary lead collections following provocative chelation have been standardized for pediatric patients, but have not been considered adequate for adults. This study compared shortened urine collections for lead excretion post chelation with standard 24-hour collections. Thirty-five patients without known current lead exposure and with serum creatinine measurements less than 2 mg/dL were hospitalized and had provocative chelation performed as follows: One gram of CaNa2-ethylenediaminetetraacetic acid (EDTA) was administered in 250 mL of a 5% dextrose in water solution intravenously over one hour; the same dose was repeated 12 hours later. A 24-hour urine collection for lead excretion was begun at the time of initiation of the first dose. At three hours and six hours from start of first dose, each patient was instructed to void, total volume to that point was recorded, and a 10-mL aliquot was withdrawn for lead measurement. Both three-hour and six-hour urinary lead excretion following a single dose of EDTA correlated linearly with 24-hour lead excretion post chelation (r = .89 and .94, respectively). When a 24-hour level of 600 micrograms was defined as "true positive" the three-hour collection had a sensitivity of 76% and specificity of 95% and six-hour urinary lead excretion had 82% sensitivity and 100% specificity. Mild renal insufficiency (reflected by serum creatinine levels between 1.5 and 2.1 mg/dL) did not significantly alter the correlation between three-, six-, and 24-hour urinary post-chelation lead excretion.

Relationship between gastric mucus synthesis, secretion and surface gel erosion measured in amphibian stomach in vitro.

1. The layer of adherent mucus that protects the surface of the stomach reflects a dynamic balance between biosynthesis of glycoprotein, secretion of preformed mucus and erosion of the adherent gel layer. The present study is the first in which all these processes have been measured concomitantly and was undertaken to define interrelationships between the three parameters. 2. A chambered sac preparation of amphibian gastric mucosa is described. Biosynthesis was determined by specific incorporation of radiolabelled sugars into purified glycoprotein. Mucus secretion was determined by measuring the thickness of the adherent gel and erosion of the surface layer was assessed from the appearance of soluble mucin in the luminal solution. 3. 16,16-Dimethyl-prostaglandin (PG) E2 stimulated glucosamine incorporation by 10-fold, but did not alter the rate of incorporation of galactose. There was a rapid two-fold increase in the thickness of the adherent mucus layer but no change in the rate of erosion. Dibutyryl-cAMP also stimulated mucus release but, unlike PG, increased glycoprotein labelling by galactose. 4. Both distention or the application of a cholinergic agonist increased adherent mucus thickness. Stimulation of mucus release in response to carbachol was accompanied by a decrease in glycoprotein labelling by galactose. In contrast, the adrenergic agent noradrenaline decreased secretion but did not influence labelling. 5. These results indicate that biosynthesis and secretion of gastric mucus are subject to differential regulation. Moreover, the profile of incorporation of sugars in response to secretagogues also differs, indicating the need for caution when interpreting effects on glycoprotein biosynthesis.

Effects of exogenous transglutaminase on spreading of human colorectal carcinoma cells.

Using pre-confluent cultures of a human colon tumor cell line deficient in transglutaminase (LS174T cells), we have investigated the effect of adding exogenous transglutaminase (TGA) on cell spreading. The cells were plated at either 4.5 x 10(5) cells per well (low-seeded cultures) or 9 x 10(5) cells per well (high-seeded cultures) in 24-well dishes and treated for either 1 or 4 days (low- and high-seeded cultures respectively) under following conditions: Chee's Essential Medium (CEM) + 10% fetal calf serum (FCS); CEM + 10% FCS + TGA; CEM + 10% FCS + dithiothreitol (DTT) + CaCl2; CEM + 10% FCS + DTT + CaCl2 + TGA. Photomicrography of the cells after these treatments revealed that in both low- and high-seeded cultures, TGA inhibited the spreading of the cells both in the presence and absence of DTT and calcium. Individual colony sizes were significantly smaller in the presence of TGA. This phenomenon may be related to the ability of TGA to promote cell interactions with the underlying tissue matrices and metastasis.

Enhancement of gastric mucosal epidermal growth factor and platelet-derived growth factor receptor expression by sucralfate.

1. The effect of an anti-ulcer agent, sucralfate, on the expression of gastric mucosal epidermal growth factor (EGF) and platelet derived growth factor (PDGF) receptors was investigated. 2. Gastric mucosal cell membranes, isolated from the stomach of groups of rats, one receiving twice daily for 3 consecutive days a dose of 100 mg/kg sucralfate, and the other only the vehicle, were used as source for EGF and PDGF receptors. 3. Binding assays revealed the presence of both types of receptors, activation of which led to the elevation of tyrosine kinase activity as evidenced by a marked increase in membrane protein tyrosine phosphorylation patterns. 4. The specific receptor binding in the control group was 2.46 fmol/mg protein for EGF and 1.46 fmol/mg protein for PDGF, whereas the respective binding values in the sucralfate treated group increased by 61 and 65%. 5. The results suggest that sucralfate is capable of enhancement of epithelial proliferative activities through the stimulation of gastric mucosal EGF and PDGF receptors.

Pharmacological alterations of cellular transglutaminase activity and invasiveness in human colorectal carcinoma cells.

Human colorectal tumor cells expressing differing metastatic potential and tissue transglutaminase (TGA) activity were tested for the ability of various pharmacological agents to enhance TGA activity. The most effective stimulant was tetradecanoylphorbol-13-acetate (TPA), which in human colon carcinoma cells (SW620) caused a 5-fold, protein synthesis dependent increase in activity over 3 days. In WiDr and SW480 cells TGA activity was less susceptible to induction by TPA, possibly owing to the higher basal levels of TGA. Retinoic acid and a synthetic retinoid, [RO 15-1570; (E)-4-[2(5,6,7,8-tetramethylnaphthalene-2-yl)propen-1-yl] benzenesulphonyl-ethane)], also induced TGA activity to a lesser extent in SW620 cells, whereas other differentiation inducers [sodium butyrate and hexamethylene bis-acetamide (HMBA)] were ineffective. In LS174T cells, TGA activity was resistant to induction by all of the agents. The synthetic retinoid (RO 15-1570) inhibited in vitro invasiveness of SW620 cells, however, TPA treatment or addition of exogenous TGA did not inhibit invasiveness of these cells. Hence, the invasive behavior of a metastatic human colon tumor cell line (SW620) does not appear to be dependent on the TGA activity which the cells express. The anti-invasive activity of the retinoid in SW620 cells therefore may be mediated by some other mechanism.

Patterns and predictors of employer risk-reduction activities (ERRAs) in response to a work-related upper extremity cumulative trauma disorder (UECTD): reports from workers' compensation claimants.

BACKGROUND: Despite being preventable, work-related upper extremity cumulative trauma disorders (UECTDs) remain problematic. This study is unique in its focus on predictors of employer risk-reduction activities (ERRAs) in response to a UECTD case. METHODS: Workers' compensation claimants (N = 537) completed a telephone survey about employer risk-reduction activities, workplace characteristics, safety programs, and physician recommendations for job modifications. RESULTS: Only 52% of respondents reported employer actions to investigate or reduce UECTD risk. Engineering and pace changes were prominent for keyboard workers and transfer to another job for manufacturing workers. Safety programs and physician recommendations increased the likelihood of risk-reduction activities. CONCLUSIONS: An opportunity to intervene post-injury to reduce risks for the injured worker and prevent new UECTD cases is being missed. Physician recommendations are strongly associated with specific ERRAs thought to be most effective. Educating employers and physicians about ergonomics could result in prevention of UECTDs.