3,5,3'-Triiodothyronine (T3) clearance and T3-glucuronide (T3G) appearance kinetics in plasma of freshwater-reared male tilapia, Oreochromis mossambicus

Distribution and metabolism of the thyroid hormone 3,5, 3'-l-triiodothyronine (T3) were studied in several ways to gain insights into these processes in the warm water fish tilapia Oreochromis mossambicus. Trace doses of 125I-labeled T3 (T*3)1 were injected intraarterially, extraarterially, or intraperitoneally in freshwater-reared male tilapia to explore plasma clearance kinetic responses to these different input modalities. Multicompartmental analysis of the plasma clearance data indicated a kinetic distribution of T*3 much like that reported for the rat and human, with about 2% of total body T*3 in plasma, 5% in rapidly exchanging tissues such as kidney and liver, and 93% in slowly exchanging tissues such as muscle. However, plasma clearance rates (PCR, 5.37 mL/h . 100 g body wt) and plasma appearance rates (PAR3 = PCR x [T3] plasma = 36.3 ng/h . 100 g body wt) were quite different than these indices in rat and human and 5 to 50 times larger than values reported for rainbow trout. On a whole-body basis, normalized for body weight, the tilapia we studied produced and accumulated much more T3 than rat, human, or rainbow trout. Enzymatic and chromatographic analyses of the plasma clearance data samples indicated substantial production of labeled glucuronide, but not sulfate, conjugates of iodothyronines (TiG) of unknown origin appearing in plasma. The TiG appeared beginning a few hours postinjection, peaked at 6 hours, and yielded a predicted steady-state TiG level of 8.3% of the T3 level in plasma. In contrast, in published studies, no conjugates were detected in rainbow trout plasma from 2 to 24 h after iv injection of T*3, T*4, or reverse-T*3, although conjugates of all were present in bile. To our knowledge, although T3 and T4 sulfate conjugates are present in the sera of several mammals, this is the first quantification of iodothyronine glucuronides reported in blood of any species under normal conditions. This might have physiological significance for the tilapia, with T3G providing a reversible storage form of T3 in blood, as has been suggested for sulfate conjugates of T3 and T4 in blood of several mammals.

Ferredoxin-1 mRNA is destabilized by changes in photosynthetic electron transport

In transgenic tobacco, pea Ferredoxin-1 (Fed-1) mRNA accumulates rapidly in response to photosynthesis even when the transgene is driven by a constitutive promoter. To investigate the role of photosynthesis on Fed-1 mRNA stability, we used the tetracycline repressible Top10 promoter system to specifically shut off transcription of the Fed-1 transgene. The Fed-1 mRNA has a half-life of approximately 2.4 hr in the light and a half-life of only 1.2 hr in the dark or in the presence of the photosynthetic electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). These data indicate that cessation of photosynthesis, either by darkness or DCMU results in a destabilization of the Fed-1 mRNA. Furthermore, the Fed-1 mRNA half-life is reduced immediately upon transfer to darkness, suggesting that Fed-1 mRNA destabilization is a primary response to photosynthesis rather than a secondary response to long-term dark adaptation. Finally, the two different methods for efficient tetracycline delivery reported here generally should be useful for half-life measurements of other mRNAs in whole plants.

Quantitation of bacteria in blood of typhoid fever patients and relationship between counts and clinical features, transmissibility, and antibiotic resistance

Salmonella typhi was isolated from 369 and Salmonella paratyphi A was isolated from 6 of 515 Vietnamese patients with suspected enteric fever. Compared with conventional broth culture of blood, direct plating of the buffy coat had a diagnostic sensitivity of 99.5% (95% confidence interval [CI], 97.1 to 100%). Blood bacterial counts were estimated by the pour plate method. The median S. typhi count in blood was 1 CFU/ml (range, <0.3 to 387 CFU/ml), of which a mean of 63% (95% CI, 58 to 67%) were intracellular. The mean number of bacteria per infected leukocyte was 1.3 (interquartile range [IQR], 0.7 to 2.4) CFU/cell (n = 81). Children (< 15 years old; n = 115) had higher median blood bacterial counts than adults (n = 262): 1.5 (range, <0.3 to 387) versus 0.6 (range, <0.3 to 17.7) CFU/ml (P = 0.008), and patients who excreted S. typhi in feces had higher bacteremias than those who did not: a median of 3 (range, <0.3 to 32) versus 1 (range, <0.3 to 68) CFU/ml (P = 0.02). Blood bacterial counts declined with increasing duration of illness (P = 0.002) and were higher in infections caused by multidrug-resistant S. typhi (1.3 [range, <0.3 to 387] CFU/ml; n = 313) than in infections caused by antibiotic-sensitive S. typhi (0.5 [range, <0.3 to 32] CFU/ml; n = 62) (P = 0.006). In a multivariate analysis this proved to be an independent association, suggesting a relationship between antibiotic resistance and virulence in S. typhi.

Insulin therapy in burn patients does not contribute to hepatic triglyceride production

Lipid kinetics were studied in six severely burned patients who were treated with a high dose of exogenous insulin plus glucose to promote protein metabolism. The patients were 20+/-2-yr-old (SD) with 63+/-8% total body surface area burned. They were studied in a randomized order (a) in the fed state on the seventh day of a control period (C) of continuous high-carbohydrate enteral feeding alone, and (b) on the seventh day of enteral feeding plus exogenous insulin (200 pmol/h = 28 U/h) with extra glucose given as needed to avoid hypoglycemia (I+G). Despite a glucose delivery rate approximately 100% in excess of energy requirements, the following lipid parameters were unchanged: (a) total hepatic VLDL triglyceride (TG) secretion rate (0.165+/-0.138 [C] vs. 0.154+/- 0.138 mmol/kg . d-1 [I+G]), (b) plasma TG concentration (1.58+/-0.66 [C] vs. 1. 36+/-0.41 mmol/liter [I+G]), and (c) plasma VLDL TG concentration (0. 68+/-0.79 [C] vs. 0.67+/- 0.63 mmol/liter [I+G]). Instead, the high-carbohydrate delivery in conjunction with insulin therapy increased the proportion of de novo-synthesized palmitate in VLDL TG from 13+/-5% (C) to 34+/-14% (I+G), with a corresponding decreased amount of palmitate from lipolysis. In association with the doubling of the secretion rate of de novo-synthesized fatty acid (FA) in VLDL TG during insulin therapy (P > 0.5), the relative amount of palmitate and stearate increased from 35+/-5 to 44+/-8% and 4+/-1 to 7+/-2%, respectively, in VLDL TG, while the relative concentration of oleate and linoleate decreased from 43+/-5 to 37+/-6% and 8+/-4% to 2+/-2%, respectively. A 15-fold increase in plasma insulin concentration did not change the rate of release of FA into plasma (8.22+/-2.86 [C] vs. 8.72+/-6.68 mmol/kg.d-1 [I+G]. The peripheral release of FA represents a far greater potential for hepatic lipid accumulation in burn patients than the endogenous hepatic fat synthesis, even during excessive carbohydrate intake in conjunction with insulin therapy.

The role of DNA methylation in expression of the p19/p16 locus in human bladder cancer cell lines

Methylation of CpG sites in the control regions of tumor suppressor genes may be an important mechanism for their heritable, yet reversible, transcriptional inactivation. These changes in methylation may impair the proper expression and/or function of cell cycle regulatory genes and confer a selective growth advantage to affected cells. Detailed methylation analysis using genomic bisulfite sequencing was performed on a series of subclones of a bladder cancer cell line in which a hypermethylated p16 gene had been reactivated by transient treatment with 5-aza-2'-deoxycytidine. Methylation of the CpG island in the promoter of the p16 gene in human bladder cancer cells did not stop the formation of a transcript initiated 20 kb upstream by the p19 promoter but did prevent the expression of a p16 transcript. Furthermore, we show that reactivant clones that expressed p16 at varying levels contained heterogeneous methylation patterns, suggesting that p16 expression can occur even in the presence of a relatively heavily methylated coding region. We also present the first functional evidence that methylation of only a small number of CpG sites can significantly down-regulate p16 promoter activity, thus providing support for the model of progressive inactivation of this tumor suppressor gene by DNA methylation.

Human orosomucoid (ORM1) subtyping: further population genetic data and reports on the feasibility to type aged blood samples and stains

Genetic polymorphism of serum orosomucoid (ORM1) was investigated in 1072 unrelated German Caucasians using isoelectric focusing followed by Western blotting and EIA. The estimated allele frequencies were ORM1 *F1 = 0.5690, ORM1 *S = 0.3927, ORM1 *F2 = 0.0368, ORM1 *F2S = 0.0009 and ORM1 *F5 = 0.0005. The method was successfully applied to determine ORM1 phenotypes in aged blood samples and blood stains. The results indicated that the ORM protein is a informative and remarkably robust blood group system.

Light regulation of Fed-1 mRNA requires an element in the 5' untranslated region and correlates with differential polyribosome association

Light regulation of Fed-1 mRNA abundance in the leaves of green plants is primarily a post-transcriptional process. Previously, we have shown that the Fed-1 mRNA light response requires an open reading frame, indicating that the light regulation of the mRNA depends on its concurrent translation. We now show that light-induced increases in Fed-1 mRNA abundance are associated with increases in polyribosome association that require both a functional AUG and a normal Fed-1 translational start context. We also present evidence that light regulation of Fed-1 mRNA levels requires more than efficient translation per se. Substitution of the efficiently translated tobacco mosaic virus Omega 5' untranslated region resulted in a loss of Fed-1 light regulation. In addition, we identified a CAT T repeat element located near the 5' terminus of the Fed-1 5' untranslated region that is essential for light regulation. We introduced two different mutations in the CAT T repeat element, but only one of these substitutions blocked the normal light effect on polyribosome association, whereas both altered dark-induced Fed-1 mRNA disappearance. The element may thus be important for Fed-1 mRNA stability rather than polyribosome loading. We propose a model in which Fed-1 mRNA is relatively stable when it is associated with polyribosomes in illuminated plants but in darkness is not polyribosome associated and is thus rapidly degraded by a process involving the CAT T repeat element.

Effects of insulin on wound healing

BACKGROUND

Insulin plus glucose, given for 7 days to hypermetabolic burn patients, has been shown to stimulate limb protein anabolism. We hypothesized that insulin plus glucose given to burn patients would also stimulate wound healing.

METHODS

Six patients with burns >40% total body surface area were randomized to receive insulin or placebo in a crossover study during the healing of their first and second donor sites. Insulin treatment was titrated at 25 to 49 U/h to achieve a plasma insulin level of 400 to 900 microU/mL for 7 days. Patients receiving insulin received dextrose 50 at 20 to 50 mL/h, titrated to maintain euglycemia. Donor-site biopsies were taken at 7 days and evaluated by three observers blinded to the treatment.

RESULTS

The mean (+/-SD) donor-site healing time was reduced from 6.5 +/- 1.0 days with placebo to 4.7 +/- 1.2 days during insulin infusion (p < 0.05). Laminin showed intense staining along the basal lamina and blood vessels. Collagen type IV staining also increased after insulin therapy compared with placebo.

CONCLUSION

Data indicate that high doses of insulin and glucose can be safely administered to massively burned patients to improve wound matrix formation.

Comparison of intestinal folate carrier clone expressed in IEC-6 cells and in Xenopus oocytes

We recently identified a cDNA clone from mouse small intestine, which appears to be involved in folate transport when expressed in Xenopus oocytes. The open reading frame of this clone is identical to that of the reduced folate carrier (RFC) (K. H. Dixon, B. C. Lanpher, J. Chiu, K. Kelley, and K. H. Cowan. J. Biol. Chem. 269: 17-20, 1994). The characteristics of this cDNA clone [previously referred to as intestinal folate carrier 1 (IFC-1)] expressed in Xenopus oocytes, however, were found to be different from the characteristics of folate transport in native small intestinal epithelial cells. To further study these differences, we determined the characteristics of RFC when expressed in an intestinal epithelial cell line, IEC-6, and compared the findings to its characteristics when expressed in Xenopus oocytes. RFC was stably transfected into IEC-6 cells by electroporation; its cRNA was microinjected into Xenopus oocytes. Northern blot analysis of poly(A)+ RNA from IEC-6 cells stably transfected with RFC cDNA (IEC-6/RFC) showed a twofold increase in RFC mRNA levels over controls. Similarly, uptake of folic acid and 5-methyltetrahydrofolate (5-MTHF) by IEC-6/RFC was found to be fourfold higher than uptake in control sublines. This increase in folic acid and 5-MTHF uptake was inhibited by treating IEC-6/RFC cells with cholesterol-modified antisense DNA oligonucleotides. The increase in uptake was found to be mainly mediated through an increase in the maximal velocity (Vmax) of the uptake process [the apparent Michaelis-Menten constant (K(m)) also changed (range was 0.31 to 1.56 microM), but no specific trend was seen]. In both IEC-6/RFC and control sublines, the uptake of both folic acid and 5-MTHF displayed 1) pH dependency, with a higher uptake at acidic pH 5.5 compared with pH 7.5, and 2) inhibition to the same extent by both reduced and oxidized folate derivatives. These characteristics are very similar to those seen in native intestinal epithelial cells. In contrast, RFC expressed in Xenopus oocytes showed 1) higher uptake at neutral and alkaline pH 7.5 compared with acidic pH 5.5 and 2) higher sensitivity to reduced compared with oxidized folate derivatives. Results of these studies demonstrate that the characteristics of RFC vary depending on the cell system in which it is expressed. Furthermore, the results may suggest the involvement of cell-or tissue-specific posttranslational modification(s) and/or the existence of an auxiliary protein that may account for the differences in the characteristics of the intestinal RFC when expressed in Xenopus oocytes compared with when expressed in intestinal epithelial cells.

Effects of gender on resting leg blood flow: implications for measurement of regional substrate oxidation

These studies were designed to examine whether the respiratory quotient (RQ) of leg tissue (primarily skeletal muscle) would increase to a greater degree in women than in men during meal ingestion. We found that mean leg and systemic RQ values were similar in men under both basal and fed conditions, whereas the agreement was poor in women. In women, leg RQ values tended to be greater than the systemic RQ, whereas splanchnic RQ values tended to be lower than the systemic RQ. The possibility that measurement imprecision accounted for the different findings in women could not be excluded because the arteriovenous blood O2 differences were almost twice as great in men as in women (53.7 +/- 5.4 vs. 28.6 +/- 2.9 ml of O2/l, respectively; P < 0.01), as were venoarterial blood CO2 differences. The smaller arteriovenous differences in women appeared to limit our ability to accurately measure their leg RQ values. O2 uptake relative to leg fat-free mass (FFM) was not different between men and women, whereas leg blood flow relative to leg FFM was greater in women than in men (55 +/- 3 vs. 39 +/- 2 ml.kg FFM-1.min-1, respectively; P < 0.001). These findings were confirmed by examining data from other studies conducted in our laboratory to create a larger data set. We conclude that resting leg blood flow in women is greater (relative to FFM) than in men, making it more difficult to accurately measure leg RQ in women.

Effect of methohexitone and propofol with or without alfentanil on seizure duration and recovery in electroconvulsive therapy

We have studied the effects of methohexitone and propofol with and without alfentanil on seizure duration and recovery in this observer-blinded, prospective, randomized, crossover study involving 24 patients undergoing electroconvulsive therapy (ECT). Each patient had four treatment sessions, and received the following four i.v. regimens in random order: methohexitone 0.75 mg kg-1, methohexitone 0.50 mg kg-1 and alfentanil 10 micrograms kg-1, propofol 0.75 mg kg-1, propofol 0.50 mg kg-1 and alfentanil 10 micrograms kg-1. Additional methohexitone or propofol was given as needed in 10-20-mg increments until loss of consciousness. Suxamethonium 1.0 mg kg-1 i.v. was given for muscular paralysis. Mean motor and EEG seizure durations were longer with methohexitone-alfentanil (44.7 (SD 15.0) and 70.5 (29.7) s) than with methohexitone (37.6 (12.6) and 52.6 (15.3) s) and similarly, seizures were longer with propofol-alfentanil (36.8 (15.2) and 54.5 (20.9) s) than with propofol alone (27.2 (11.9) and 39.2 (3.9) s). Seizures were longest with methohexitone-alfentanil and shortest with propofol. Recovery time was statistically shorter in patients receiving propofol compared with methohexitone-alfentanil and methohexitone alone. Alfentanil with a reduced dose of methohexitone or propofol provided unconsciousness and increased seizure duration in patients undergoing ECT. We conclude that the combination of methohexitone with alfentanil is a good regimen for ECT, especially for patients with short seizure duration.

Anti-IgM-induced growth inhibition and apoptosis are independent of ornithine decarboxylase in Ramos cells

Ornithine decarboxylase (ODC) is a key enzyme involved in polyamine production and is thought to regulate growth and apoptosis in multiple cell systems. A potential link between ODC and growth may involve the action of an oncogene c-myc which is thought to transcriptionally regulate ODC. We have examined the involvement of ODC in anti-IgM-induced growth inhibition and apoptosis in Burkitt's lymphoma cells. Inhibitors of ODC such as difluoromethylornithine (DFMO) completely blocked ODC activity, resulting in growth inhibition but not apoptosis. Addition of putrescine, the product of ODC enzymatic action, to Ramos cells had only a minor effect on growth, did not cause apoptosis, did not augment or block anti-IgM-mediated growth inhibition and apoptosis, but did reverse DFMO-mediated growth inhibition. Anti-IgM treatment of Ramos cells, which markedly decreased c-myc mRNA and protein, caused a paradoxical increase in ODC mRNA level as well as ODC enzymatic activity and increased cellular levels of putrescine. DFMO and putrescine did not alter c-myc mRNA levels directly, nor did they have any affects on anti-IgM-mediated down-regulation of c-myc mRNA. TNF-alpha, which inhibited anti-IgM-mediated apoptosis, did not inhibit either anti-IgM or DFMO-mediated inhibition of growth. These agents were without effect on ODC activity itself or on the anti-IgM-mediated increase in ODC activity. From these studies we conclude that ODC inhibition affects growth but is unrelated to the induction of apoptosis. Both anti-IgM-mediated inhibition of growth and induction of apoptosis are independent of ODC. Thus two distinct pathways for growth regulation are present: one in which ODC and polyamines are important and the other cell surface receptor-mediated (sIg) which is independent of ODC and polyamines.

Risk stratification prior to vascular surgery: does the location of a dipyridamole thallium scintigram defect provide prognostic information?

BACKGROUND

While the value of myocardial scintigraphy using dipyridamole thallium is accepted for risk assessment prior to vascular surgery, it is unknown whether the location of the thallium abnormalities provides prognostic information.

METHODS

Records from 435 consecutive patients scheduled for vascular surgery were reviewed and patients with dipyridamole thallium abnormalities involving the anterior distribution (ANTERIOR n = 62), or inferior or inferolateral distribution (INFERIOR n = 105) were assessed for cardiac complications of surgery (death, myocardial infarction, unstable angina or ischemic congestive heart failure).

RESULTS

Patients with a normal dipyridamole thallium scintigraphy had few surgical cardiac complications: 2/86 (2%). Patients with an ANTERIOR dipyridamole thallium defect had a 12% incidence of surgical cardiac complications (7/57) without any cardiac deaths, while patients with an INFERIOR dipyridamole thallium defect had a similar incidence of surgical cardiac complications, 18% (18/100; p = 0.65 vs. ANTERIOR) including 4 cardiac deaths.

CONCLUSIONS

Significant inferior or inferolateral dipyridamole thallium scintigraphy abnormalities are not associated with a lower risk of cardiac complications following vascular surgery than anterior abnormalities. Rather, any clearly abnormal dipyridamole thallium study is a marker for increased risk of perioperative events and may warrant further evaluation and treatment.

Involvement of supraspinal GABA-ergic systems in clonidine-induced antinociception in the tail-pinch test in mice

We investigated the involvement of supraspinal GABAergic systems in the antinociceptive effect of clonidine using the tail-pinch test in mice. Muscimol (31.2-250 ng/mouse, i.c.v.) and R(+)-baclofen (10-100 ng/mouse, i.c.v.), selective agonists for the GABA(A) and GABA(B) receptors, respectively, significantly attenuated the antinociceptive effect of subcutaneously (s.c.) administered clonidine (1 mg/kg) in a dose-dependent manner. The attenuating effect of muscimol (62.5 ng/mouse, i.c.v.) on the clonidine-induced antinociception was significantly blocked by the GABA(A) antagonists bicuculline (100-400 ng/mouse, i.c.v.) and picrotoxin (250 ng/mouse, i.c.v.) but not by the GABA(B) antagonist 2-hydroxysaclofen (10 microg/mouse, i.c.v.). On the other hand, the attenuating effect of R(+)-baclofen (50 ng/mouse, i.c.v.) was blocked by the coadministration with 2-hydroxysaclofen (20 microg/mouse), but was not affected by the coadministration with bicuculline (400 ng/mouse). These results indicate that both supraspinal GABA(A) and GABA(B) receptors play inhibitory roles in the antinociception caused by systemically administered clonidine.

Fluoride profiles in dental calculus from Japanese, Chinese and British residents

Whether the fluoride concentrations and profiles differ in human dental calculus obtained from different countries was investigated. A total of 203 dental calculus deposits on 203 permanent teeth from residents (mean age, 52.1 years) of Nagoya (Japan), Shanghai (China), Leeds (Great Britain) and the Wuhan mountainous area (China, fluoridated area) were analysed. An abrasive microsampling procedure was used to examine fluoride distribution. There were five types of fluoride profiles in dental calculus in each area/country (designated types L, J, U, T, W). In supragingival calculus, type L (highest in the outermost layers) and type J (highest in the innermost layers) both had significantly higher values than type U (high in the surface and innermost layers) but were relatively identical. In subgingival calculus, type W (high in the outermost, mid and innermost layers) was characteristics. Calculus from the Wuhan mountainous area (fluoridated) had the highest fluoride concentration, followed by Leeds (non-fluoridated), and Nagoya and Shanghai (non-fluoridated) calculus had the lowest. Fluoride concentrations in supragingival calculus were higher in teeth extracted because of periodontal diseases than dental caries. It is concluded that fluoride concentrations and distribution in dental calculus differ from country to country, probably due to different fluoride environments.

Effect of hydroxyl radical scavenging capacity on clustering of DNA damage

We have shown previously that the thiol N-(2'-mercaptoethyl)-1,3-diaminopropane (WR-1065) can attenuate the formation of strand breaks associated with ionizing radiation. The mechanism of this protection is predominantly the reduction of DNA radical species which otherwise would attenuate the chemical repair of DNA radical species which are strand break precursors. We had observed that the presence of a hydroxyl radical scavenger during irradiation resulted in a decrease in the ability of WR-1065 to attenuate the formation of strand breaks. Since ionic compounds are known to affect the binding of the dicationic WR-1065 with the polyanion DNA, the effect of the scavenger was initially attributed to its polar nature having a similar effect on the interaction of WR-1065 with DNA, and not as a consequence of its ability to scavenge hydroxyl radicals. After examining additional scavengers, we now conclude that an increased hydroxyl radical scavenging capacity does attenuate the repair of strand break precursors to some extent. The probable explanation for this observation is that an increased scavenging capacity results in a greater degree of radical clustering on the DNA, and that these clusters of multiple radicals are repaired more slowly than are single radical species.

Predictive value of electrophoretically detected lipoprotein(a) for coronary heart disease and cerebrovascular disease in a community-based cohort of 9936 men and women

BACKGROUND

Elevated lipoprotein(a) [Lp(a)] levels have been associated with the presence of atherosclerotic disease. However, the results of prospective studies of Lp(a) and cardiovascular disease have been contradictory.

METHODS AND RESULTS

From 1968 through 1982, lipoprotein analysis was performed in 11,335 Olmsted County residents. Quantitative cholesterol and triglycerides were obtained along with semiquantitative Lp(a) levels based on electrophoretic pattern. Lp(a) bands were scored from 0 (absent) to 3 (increased). A cohort of 4967 men and 4968 women with no prior history of atherosclerotic disease who had baseline Lp(a) determinations were followed up for 14 years for development of coronary artery disease (CAD) and cerebrovascular disease (CVD). During 131,330 person-years of follow-up, there were 1848 CAD events and 841 CVD events. Age, diabetes, hypertension, cholesterol, and triglycerides were significantly and independently associated with an increased risk of CAD and CVD in men and women. There was a significant increase in the adjusted hazards ratio for CAD with increasing Lp(a) levels for men and women. For Lp(a) level 3, the hazard ratio was 1.9 (range, 1.3 to 2.9) in women and 1.6 (range, 1.0 to 2.5) in men. The adjusted hazard ratio for CVD showed an irregular association with Lp(a) levels in men and no association in women.

CONCLUSIONS

In this cohort of 9936 men and women initially free of cardiovascular disease who were followed up for 14 years, Lp(a) was a significant predictor of risk of future CAD. Lp(a) was a weak risk factor for CVD in men and was not a significant predictor of CVD risk in women.

Antisense properties of end-modified oligonucleotides targeted to Ha-ras oncogene

Phosphodiester oligodeoxyribonucleotides linked to an intercalating agent or a dodecanol tail or both complementary to the 12th codon region of Ha-ras mRNA were compared with the unmodified oligonucleotides of the same size and sequence with respect to their ability to induce RNaseH cleavage and antisense activity in cell culture. The hydrophobic tail not only protected the oligonucleotide from nucleases but also enhanced RNase H cleavage of the target. Oligonucleotides carrying both an acridine and a dodecanol substituent inhibited the proliferation of HBL100ras1 cells (human mammary cells stably transformed with the T24 Ha-ras gene carrying a G-->T point mutation in codon 12) at a 20-fold to 30-fold lower concentration than unmodified ones. Therefore, these modified oligonucleotides may prove useful for antisense applications.

Fractures after thyroidectomy in men: a population-based cohort study

Bone mass is purportedly reduced by an endogenous or exogenous excess of thyroid hormone or, perhaps, by calcitonin deficiency. Patients who have undergone thyroidectomy could be subject to all of these effects, yet their practical implications in terms of fracture risk are poorly defined. Interpretation is further hampered by the focus on women, where results may be influenced by involutional osteoporosis. Consequently, we assessed the potential for fractures among the 136 Rochester, Minnesota men who underwent thyroidectomy between 1935 and 1979, relative to a group of age-matched control men from the community. With 2194 person-years of follow-up in each group, survival free of any fracture of vertebra, proximal humerus, distal forearm, pelvis, or proximal femur was similar in the two groups (p = 0.23), and the relative risk of any of these fractures for thyroidectomized patients versus their controls was increased only 1.5-fold (95% CI, 0.7-3.2). The difference was entirely accounted for by a statistically significant excess of proximal femur fractures in the men with thyroidectomy. Risk factors for fractures among men with thyroidectomy included greater age at surgery, greater extent of surgery, and the presence of risk factors for secondary osteoporosis. Thus, thyroidectomy, performed mainly for adenoma or goiter, seems to have little overall influence on the risk of age-related fractures in men. However, the association with hip fractures requires further evaluation.

Short courses of ofloxacin for the treatment of enteric fever

Typhoid fever continues to be a major public health problem in tropical countries, exacerbated in recent years by the spread of multi-drug resistant strains of Salmonella typhi. Short treatment courses of fluoroquinolones are effective, and have the advantage of reduced cost and increased compliance, but the optimal length of treatment is unknown. In an open, randomized comparison, 107 adults with uncomplicated enteric fever (95 of whom had positive blood cultures for S. typhi and 5 for S. paratyphi) were treated with oral ofloxacin, 15 mg/kg/d for 2 d or 10 mg/kg/d for 3 d. Mean fever clearance times were the same in the 2 treatment groups (97 h). There were 7 treatment failures, one in the 2 d group and 6 in the 3 d group (P = 0.07). Three of the 5 patients infected with nalidixic acid resistant strains of S. typhi had treatment failures, compared with 4 of 90 with nalidixic acid sensitive isolates (P < 0.0001; relative risk 13.5, 95% confidence interval 4.1-43%). Treatment with ofloxacin for 2 or 3 d is equally effective in adults with uncomplicated enteric fever caused by nalidixic acid sensitive strains of S. typhi. The epidemiology and management of nalidixic acid resistent typhoid needs further investigation.

Comparison of artemisinin suppositories, intramuscular artesunate and intravenous quinine for the treatment of severe childhood malaria

Severe malaria remains a major cause of mortality and morbidity for children living in many tropical regions. With the emergence of strains of Plasmodium falciparum resistant to both chloroquine and quinine, alternative antimalarial agents are required. The artemisinin group of compounds are rapidly effective in severe disease when given by intramuscular or intravenous injection. However, these routes of administration are not always available in rural areas. In an open, randomized comparison 109 Vietnamese children, aged between 3 months and 14 years, with severe P.falciparum malaria, were allocated at random to receive artemisinin suppositories followed by mefloquine (n = 37), intramuscular artesunate followed by mefloquine (n = 37), or intravenous quinine followed by pyrimethamine/sulfadoxine (n = 35). There were 9 deaths: 2 artemisinin, 4 artesunate and 5 quinine-treated children. There was no difference in fever clearance time, coma recovery, or length of hospital stay among the 3 groups. However, parasite clearance times were significantly faster in artemisinin and artesunate-treated patients than in those who received quinine (P < 0.0001). Both artemisinin and artesunate were very well tolerated, but children receiving these drugs had lower peripheral reticulocyte counts by day 5 of treatment than those in the quinine group (P = 0.011). No other adverse effect or toxicity was found. There was no treatment failure in these 2 groups, but 4 patients in the quinine group failed to clear their parasites within 7 d of starting treatment and required alternative antimalarial therapy. Artemisinin suppositories are easy to administer, cheap, and very effective for treating children with severe malaria. In rural areas where medical facilities are lacking these drugs will allow antimalarial therapy to be instituted earlier in the course of the disease and may therefore save lives.

Human intestinal folate transport: cloning, expression, and distribution of complementary RNA

BACKGROUND & AIMS

Despite intensive investigations, very little is known about the molecular identity(ies) of the intestinal folate transport system(s), especially in humans. The aim of this study was to isolate a functional human intestinal folate carrier complementary DNA (cDNA) clone and determine the distribution of complementary RNA at the tissue and cellular levels.

METHODS

Hybridization screening, modified Marathon cDNA amplification, expression in Xenopus oocytes, Northern analysis, and in situ hybridization were used.

RESULTS

The hIFC-1 cDNA contains an open reading frame for 591 amino acids (relative molecular mass = 64,826, pI = 9.4, 12 transmembrane domains, three protein kinase C phosphorylation sites, and one N-glycosylation site) with 74% DNA and 66% amino acid sequence homologies with the mouse cDNA counterpart. Xenopus oocytes injected with hIFC-1 cRNA show induced folate uptake that was (1) saturable with substrate concentration (apparent Michaelis constant = 0.71 +/- 0.06 micromol/L; maximum velocity = 128 +/- 3 fmol x h(-1) x oocyte(-1)), (2) inhibited by methotrexate, folinic acid, and folic acid (Ki = 0.84 micromol/L, 0.71 micromol/L, and 10 micromol/L, respectively), and (3) sensitive to 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (Ki = 0.29 mmol/L). Northern analysis showed wide distribution of hIFC1-complementary messenger RNA species in various human tissues. In situ hybridization on sections of human jejunum showed preferential hIFC-1 expression in epithelial cells, especially in the upper half of the villi.

CONCLUSIONS

These results represent the first molecular characterization of a human small intestinal folate carrier.

Pharmacokinetics of oral artesunate in children with moderately severe Plasmodium falciparum malaria

The pharmacokinetic properties of oral artesunate (3 mg/kg) were determined in 10 Vietnamese children, aged from 6 to 15 years, with acute falciparum malaria of moderate severity. Plasma concentrations were measured using a bioassay and expressed in terms of antimalarial activity equivalent to dihydroartemisinin, the principal biologically active metabolite. Oral artesunate was absorbed rapidly with a mean time to peak plasma bioactivity of 1.7 h (95% confidence interval [95% CI] 0.8-2.6). There was wide variation in peak plasma concentrations with a mean value equivalent to 664 ng of dihydroartemisinin/mL (95% CI 387-9410, range 179-1395) and a four-fold variation in the area under the plasma concentration-time curves. Elimination from plasma was rapid with a mean (95% CI) half-life of 1.0 h (95% CI 0.8-1.4). Plasma antimalarial levels were below the limit of detection in all cases by 12 h, despite the relatively high dose of artesunate used. Oral artesunate is rapidly absorbed and rapidly eliminated in children with moderately severe malaria but there is considerable variation between individuals.

Lipids and lipoproteins in women

Coronary artery disease (CAD) is the most common cause of death in women in the United States. Dyslipidemia is a risk factor for CAD in both men and women. Low levels of high-density lipoprotein (HDL) cholesterol and hypertriglyceridemia, especially in association with a dense low-density lipoprotein (LDL) phenotype, may be of greater importance in women than in men. The relationship between CAD and dyslipidemia and the therapeutic approach to disorders of lipid metabolism in women have unique features because of the effects of exogenous and endogenous hormones on lipid pathways. Estrogen decreases LDL cholesterol and Lp(a) lipoprotein and increases triglyceride and HDL cholesterol levels. Progestogens decrease triglycerides, HDL cholesterol, and Lp(a), and they increase LDL cholesterol. Thus, oral contraceptives increase plasma triglycerides, whereas the effect of these agents on LDL cholesterol and HDL cholesterol levels is related to the androgenicity and dose of progestogen. Postmenopausal hormone replacement therapy increases triglycerides and decreases LDL cholesterol. The effect of hormone replacement therapy on HDL cholesterol is influenced by the addition of progestogen. Although no primary prevention studies have analyzed lipid lowering and CAD in women, secondary prevention studies have suggested that the response to drug treatment and the benefit of lipid lowering are similar in women and in men. Hormone replacement therapy should be considered in the treatment of hypercholesterolemia in postmenopausal women; however, individualization of treatment is important to avoid adverse effects.

Streaming potentials during the confined compression creep test of normal and proteoglycan-depleted cartilage

The streaming potential response of cartilage in the confined compression creep configuration was assessed theoretically and measured experimentally in normal and proteoglycan-depleted tissue. The analytical solution, using the linear biphasic continuum model including electrokinetics and assuming homogeneous material properties, predicted that: (i) the peak streaming potential is delta V = ke x delta sigma, where ke is the electrokinetic coefficient and delta sigma is the change in compressive stress; (ii) the potential is maintained at 95 to 100% of the peak value for 0 < t < 0.10 tau, where tau is the gel diffusion time constant; and (iii) during short times, 0 < t < 0.01 tau, 90% of the peak streaming potential occurs over a region extending 23% into the tissue sample. Experimentally, adult bovine cartilage disks, 0.5 mm thick, were subjected to step changes of compressive stress. The measured changes in potential indicated a linear response for changes in stress up to 0.10 MPa. The ke of normal cartilage, estimated from the short time (0 < t < 2 sec) change in potential, was -1.65 +/- 1.25 mV/MPa. Digestion of cartilage by chondroitinase ABC resulted in an increased (less negative) ke of -0.75 +/- 0.70 mV/MPa and a 33 +/- 29% depletion of anionic glycosaminoglycan, whereas digestion with trypsin resulted in a further increase in ke to +1.74 +/- 0.95 mV/MPa and a 98 +/- 1 % depletion of glycosaminoglycan. The streaming potential measurement may be a useful addition to the widely used confined compression creep test to assess cartilage material properties.