Experimental and computational chemical studies on the corrosion inhibition of new pyrimidinone derivatives for copper in nitric acid

Inhibition of copper corrosion by some pyrimidinone derivatives, namely; (E)-N-(3-((1,3-dimethyl-2,4,6-trioxohexahydropyrimidin-5-yl)diazenyl)-2,5-diethoxyphenyl)benzamide (MA-975) and(E)-6-(4-((4-chlorophenyl)diazenyl)-3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)-1,3 dimethylpyrimidine-2,4(1H,3H)-dione (MA-978C) in 1.0 M nitric acid (HNO₃) was studied using weight loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP) measurements. The efficiency of inhibition increases as the concentration of inhibitor increases, and it also increases as the temperature increases. With the addition of the examined inhibitors, significant corrosion protection was obtained, and (MA-975) showed a very promising % IE (89.59%) at 21 × 10⁻⁶ M using the (WL) method. The polarization data revealed that these compounds act as mixed-type compounds and are adsorbed on the copper surface following Langmuir adsorption isotherm forming a protective thin film protecting the metal in the corrosive media. Scanning electron microscopy (SEM) and Energy Dispersive X-ray were used to examine the surface morphology of copper samples. Quantum calculations and Monte Carlo simulation techniques were applied with informative yields and the results matched the experimental findings.

Imaging findings in MR imaging-guided focused ultrasound treatment for patients with essential tremor

BACKGROUND AND PURPOSE

MR imaging-guided focused sonography surgery is a new stereotactic technique that uses high-intensity focused sonography to heat and ablate tissue. The goal of this study was to describe MR imaging findings pre- and post-ventralis intermedius nucleus lesioning by MR imaging-guided focused sonography as a treatment for essential tremor and to determine whether there was an association between these imaging features and the clinical response to MR imaging-guided focused sonography.

MATERIALS AND METHODS

Fifteen patients with medication-refractory essential tremor prospectively gave consent; were enrolled in a single-site, FDA-approved pilot clinical trial; and were treated with transcranial MR imaging-guided focused sonography. MR imaging studies were obtained on a 3T scanner before the procedure and 24 hours, 1 week, 1 month, and 3 months following the procedure.

RESULTS

On T2-weighted imaging, 3 time-dependent concentric zones were seen at the site of the focal spot. The inner 2 zones showed reduced ADC values at 24 hours in all patients except one. Diffusion had pseudonormalized by 1 month in all patients, when the cavity collapsed. Very mild postcontrast enhancement was seen at 24 hours and again at 1 month after MR imaging-guided focused sonography. The total lesion size and clinical response evolved inversely compared with each other (coefficient of correlation = 0.29, P value = .02).

CONCLUSIONS

MR imaging-guided focused sonography can accurately ablate a precisely delineated target, with typical imaging findings seen in the days, weeks, and months following the treatment. Tremor control was optimal early when the lesion size and perilesional edema were maximal and was less later when the perilesional edema had resolved.

Caesarean scar endometriosis presenting as an acute abdomen: a case report and review of literature

OBJECTIVE

To report a case of Caesarean scar endometriosis presenting as acute abdomen and a review of literature.

DESIGN

Case report and literature review.

PATIENT

A 27-year-old woman presented in Accident and Emergency Department with pain and lump near left edge of pfannenstiel incision scar.

INTERVENTION

After initial investigations the patient underwent examination under anesthesia.

MAIN OUTCOME MEASURE

Excision of a tumour-like mass adherent to the skin and the surrounding subcutaneous tissue. The mass was dissected free from the surrounding fat tissue and excised with clear margins.

RESULT

Histology of the mass confirmed endometriosis in tumour and showed a 2 cm fibrotic nodule within.

CONCLUSION

In light of increasing rate of caesarean section, it is important to emphasize the early diagnosis as well as optimum management of scar endometrioma. Many recommendations have been given to modify practices at caesarean section to prevent transplantation of decidual endometrial tissue in the abdominal scar but without any published randomised trials.

Antioxidant vitamins E and C as adjunct therapy of severe acute lower-respiratory infection in infants and young children: a randomized controlled trial

OBJECTIVE

To evaluate the effect of antioxidant Vitamins E and C as adjunct therapy of severe acute lower respiratory infection (ALRI) in children.

DESIGN

Randomized double-blind placebo-controlled clinical trial.

SETTING

A large childrens' hospital serving the urban poor in Kolkata, India.

SUBJECTS

Children aged 2-35 months admitted with severe ALRI.

INTERVENTION

In total, 174 children were randomly assigned to receive alpha-tocopherol 200 mg and ascorbic acid 100 mg twice daily or placebo for 5 days. All children received standard treatment for severe ALRI. Outcome measures were: time taken to recover from a very ill status, fever, tachypnoea, and feeding difficulty; and improvement in oxidative stress and immune response indicated by thiobarbituric acid reacting substances (TBARS) and response to skin antigens, respectively.

RESULTS

Recovery rate ratios (95% CI) using proportional hazards model were 0.89 (0.64-1.25), 1.01 (0.72-1.41), 0.86 (0.57-1.29), and 1.12 (0.77-1.64) for very ill status, feeding difficulty, fever, and tachypnoea, respectively. TBARS values were high and similar in the two groups at admission, discharge, and at 2 weeks follow-up. Serum alpha-tocopherol significantly increased in treated group at discharge. Immune response to skin antigens were very poor at admission and after 2 weeks, in both groups.

CONCLUSION

Infants with severe ALRI failed to benefit from two antioxidant nutrients as adjunct therapy. Severe ALRI in infants may cause cell-mediated immune dysfunction. We need a better understanding of oxidative processes in growing infants to help us better design interventions with antioxidant therapy.

Evaluation of stool antigen test for Helicobacter pylori infection in asymptomatic children from a developing country using 13C-urea breath test as a standard

OBJECTIVE

Prevalence of asymptomatic Helicobacter pylori infection is very high in infants and children in developing countries. C urea breath test (UBT) is a reliable non-invasive diagnostic test for H. pylori infection in children that avoids invasive endoscopy. We compared a newly introduced H. pylori stool antigen test (with a high sensitivity and specificity in symptomatic children) with UBT in asymptomatic children mostly 1-5 years old, from a population with a high prevalence of infection.

METHOD

Eighty six asymptomatic children (42 boys and 44 girls) were tested for H. pylori infection using the UBT and a stool antigen test (HpSA) based on a sandwich enzyme immunoassay for antigen detection.

RESULTS

Forty five of the eighty-six (52.3%) children tested positive for H. pylori using the breath test. In 34 of these forty-five children, H. pylori antigen was detected in stool (sensitivity = 75.6%, 95% CI = 63 to 88%). Of the 50 of 86 (58%) children positive by HpSA test, 34 were positive for breath test. Of the 41 children with negative UBT test 25 were negative for stool antigen test (specificity = 61%, 95% CI = 46 to 76%).

CONCLUSION

The sensitivity and specificity of the new stool antigen test are lower in asymptomatic children with high H. pylori prevalence rate compared to those reported for children with gastrointestinal symptoms. Its usefulness is limited for diagnosis in an asymptomatic child with H. pylori infection.

Lean body mass in preschool aged urban children in India: gender difference

OBJECTIVE

To estimate lean body mass (LBM) in preschool aged boys and girls in India and explore gender difference.

DESIGN

Crossectional.

SETTING

Immunization clinic of a charitable Government General Hospital in Kolkata, India.

SUBJECTS

Two-hundred and forty-five children (147 boys and 98 girls) aged 1-5 y from among the urban poor were admitted in the study between July 1999 and December 2000. Children with acute or chronic illness or congenital malformation were excluded.

METHOD

Length/height to the nearest 0.1 cm, weight to the nearest 10 g and total body resistance using multifrequency bioelectrical (Xitron 4000B) impedance analyzer (BIA) at 50 kHz were measured. Their nutritional status was compared with National Center for Health Statistics (NCHS) median data and lean body mass (LBM) was calculated using anthropometry and BIA equations. The groups were compared using analysis of variance and multiple linear regression.

RESULTS

Girls were more stunted (P<0.001) and underweight (P<0.047), while the degree of wasting was similar. Mean LBM percentage was higher in boys compared with girls by anthropometry (P<0.001) and BIA (P<0.005), which persisted after adjusting for age. With increasing age, LBM percentage declined in girls (P<0.02) in contrast to reference girls, in whom it increased. In boys LBM percentage increased with age as is in reference boys.

CONCLUSIONS

In addition to the girls being more stunted and underweight, LBM% decreased in girls with increasing age but steadily increased in boys, suggesting hidden deprivation of female children.

Energy intake and expenditure of obese and non-obese urban Bangladeshi children

A case control study was conducted in Dhaka city to measure the energy intake and expenditure among 220 obese children of 4-10 years age group and 220 randomly selected age and sex matched controls. A 24 hour dietary recall was used to assess the energy intake. Data on energy expenditure was obtained by 24 hour physical activity recall. The mean energy intake of obese children (2056 +/- 751 kcal/d) was found to be significantly higher (P<0.001) compared to the non obese (1508 +/- 529 kcal/d). No sex difference was found in both obese and non obese groups. Mean energy expenditure of the obese children (1868 +/- 313 kcal/d vs 1495 +/- 200 kcal/d) was significantly higher than the non-obese (P<0.001). Of the obese, boys expended more energy than the girls (P=0.01). Furthermore, physical activity level (1.40 +/- 0.09 vs 1.35 +/- 0.14) was significantly higher among the non obese than their obese counterpart (P<0.001). However, energy balance was significantly higher among the obese (P<0.001). Dose response of energy balance shows the estimated relative risk of obesity increases with higher level of energy balance (P<0.001). The findings of this study revealed that energy balance as a result of higher energy intake and lower energy expenditure was one of the important risk factors for the development of obesity among the children of Dhaka city. Thus, appropriate interventions like behavioural change regarding food habits and physical activities are recommended.

Risk factors for pneumonia in infants and young children and the role of solid fuel for cooking: a case-control study

We evaluated the risk factors for childhood pneumonia with particular reference to indoor air-pollution associated with solid fuel use for cooking (e.g. coal, wood, dung), using a case-control study in a children's hospital in Calcutta. Cases were 127 children aged 2-35 months of either sex admitted with pneumonia and controls were 135 children attending their immunization clinic. Solid fuel use (odds ratio = 3.97, CI = 2.00-7.88), history of asthma in the child (OR = 5.49, CI = 2.37-12.74), poor economic status indicator (OR = 4.95, CI = 2.38 to 10.28), keeping large animals (OR = 6.03, CI = 1.13-32.27) were associated with high risk of pneumonia after adjusting for confounding (logistic regression analysis). Nearly 80% of people in India use such smoke producing fuel and the population attributable risk would be very high. This finding has important health policy implications. Furthermore, history of asthma is a useful prognostic indicator for early action for prevention of severe pneumonia.

Female genital mutilation

Female genital mutilation (FGM) is practiced worldwide, including in the UK. The term ‘female circumcision’ suggests a relatively benign procedure, inviting comparison with male circumcision, which, although usually medically unnecessary and uncomfortable, rarely causes long-term problems. In fact, the female procedure is responsible for long-term gynaecological morbidity and greatly increased mortality and morbidity in childbirth for both mother and baby.

For many reasons - cultural, religious and sexual - worldwide efforts to reduce the practice are meeting resistance. This paper sets out the methods and classification of FGM, the position of the World Health Organization and other international agencies, and considers the problems from a British perspective.

Higher body fat aggravates toxin-induced infectious episodes

Animal models using rabbits were developed to accumulate a variable body fat mass (FM) in two groups of animals while the fat-free mass (FFM), eg, total body protein, was maintained essentially similar between the groups. Thiobarbituric acid-reactive substances (TBARS) were measured as an index of lipid peroxidation and were found to be higher in the whole-body tissues of animals with a higher FM. Bacterial toxin (lipopolysaccharide [LPS]) also induced higher lipid peroxidation in animals with a higher FM, with a concomitant incidence of bloody mucous diarrhea. To our knowledge, this is the first evidence to show the effect of body FM to aggravate toxin-induced infections leading to diarrhea. The overall results suggest further investigations to explore the possible role of body fat in infectious diseases in humans.

Increased height gain of children fed a high-protein diet during convalescence from shigellosis: a six-month follow-Up study

The impact of dietary supplementation on catch-up growth was evaluated in 69 malnourished children ages 24-60 mo after recovery from shigellosis. They were fed either a high-protein (HP) diet with 15% of energy as protein, or a standard-protein (SP) diet with 7.5% energy as protein, for 3 wk in a metabolic study ward. Children were followed up bi-weekly for 6 mo by trained health assistants when anthropometric measurements and information of any illness were collected. Thirty-one children in the HP group and 28 children in the SP group completed 6-mo follow-up. The increase in height (mean +/- SD) was 5.3 +/- 1.0 cm vs. 4.1 +/- 1.1 cm for HP and SP groups, respectively (P < 0.001), whereas increase in body weight was 1.39 +/- 0.58 and 1.29 +/- 0.72 kg for children fed HP and SP, respectively (P = 0.59). The proportion of children who were severely stunted (< -2 SD height-for-age) decreased from 45 to 29% in the HP group compared to 50 to 46% in the SP group (P < 0.05) at 6-mo follow-up. The number of diarrheal episodes per child tended to be lower in the HP vs. SP than in the SP group (1.9 vs. 2.3, P = 0.41). These results demonstrate that feeding an HP diet to the malnourished children during recovery from shigellosis enhanced linear growth with a modest reduction in diarrheal morbidity during the 6-mo follow-up period.

Intra- and extracellular water dynamics on rehydration in cholera and noncholera patients

To estimate the intra- and extracellular body water compartments during rehydration of patients with cholera and noncholera diarrhea by bioimpedance analyzer, we studied 30 patients with acute watery diarrhea. Total body water (TBW), intracellular water (ICW), and extracellular water (ECW) of severely dehydrated adult patients were measured with a dual frequency bioimpedance analyzer at different phases of rehydration. Fluid compartments between cholera and noncholera patients were compared. Cholera patients gained more TBW than noncholera patients during recovery. Unlike patients with noncholera diarrhea, the gain in cholera patients was mainly contributed by the ICW (1.5 +/- 1.6 vs 3.0 +/- 1.2 liters, respectively, P < 0.01). It was also observed that the recovery of the ICW compartment in cholera patients occurred rapidly within the first 2 hr after infusion. Differential dynamics of body water compartments in cholera compared to noncholera patients as observed in this study may contribute further to understanding the mechanism of dehydration in diarrheal disease, which might help in improving case management.

Nutritional support and growth in thalassaemia major

Twelve thalassaemic children under 3 years of age received intensive nutritional support for one month and were discharged on a prescribed diet of locally available foods. Anthropometry, bioelectrical impedance analysis and dietary intake were longitudinally assessed. Mean energy intake was 20% greater than the recommended daily allowance during nutritional supplementation as compared with below the recommended daily allowance before and after the period of nutritional support. Weight, but not height, significantly increased during the support period and was due to increases in both fat free mass and fat mass. Body weight, fat free mass and fat mass declined in line with the reduced intake upon return home; however, height velocity accelerated and exceeded normal through the fourth month before resuming a below normal rate. It can be concluded that (1) nutritional stunting as the result of reduced nutrient intake is an important cause of growth failure in young children with thalassaemia and is responsive to nutritional support, (2) the deficit in height velocity was due to retarded truncal height growth, and (3) the bioelectrical impedance analysis method is suitable for body composition analysis of thalassaemic children.

Bioelectrical impedance measurements at various frequencies to estimate human body compositions

Bioelectrical impedance analyses (BIA) operating at various frequencies were used to estimate body composition parameters and compared with the biochemically determined parameters by using isotopic dilution method in 22 healthy adult (30-50 years old) male human subjects. BIA instruments, operating at 50,100 KHz and 5 to 500 KHz range, were used to measure body compositions, namely total body water (TBW), fat free mass (FFM), and fat mass (FM). TBW of these subjects was also determined by deuterium dilution method. BIA methods measured at 100 KHz and using multifrequencies appear to be more accurate than at 50 KHz when compared with isotopic dilution method as standard. This accuracy could be attributed due to measurements made at higher frequencies that falls in the region where current passes through both extra- and intracellularly, thereby giving an appropriate measure of TBW. All the subjects participated in this study belong socioeconomically to the middle class and do not apparently look obese or fatty. However, the mean of their body fat, as estimated by the standard deuterium dilution method, was about 30% which is suggestive of an unapparent obesity prevailing in this class of people in Bangladesh.

Acute respiratory infections prevent improvement of vitamin A status in young infants supplemented with vitamin A

At immunization contact, 165 infants 2.5 mo old were randomly assigned to receive either 15 mg vitamin A (retinyl palmitate) or placebo. Three doses were given at monthly intervals with each diphtheria, pertussis, tetanus and oral polio (DPT/OPV) immunization dose. The diarrhea and acute respiratory infection (ARI) morbidity was similar in the vitamin A and placebo groups. However, the duration (days per child-year, mean +/- SD) of ARI was less in the vitamin A group compared with placebo group (27.6 +/- 17.1 vs. 40.8 +/- 22.7; P = 0.005). Fasting retinol concentrations were measured at entry and in 61 infants, the relative dose response (RDR) test was done 1 mo after the third dose of vitamin A. Eighty-five percent of the infants had serum retinol concentration < 0.70 mol/L at entry. After 3 mo the serum retinol levels improved significantly in both groups, and in the vitamin A-supplemented group the serum retinol concentration was significantly better than that in the placebo group (P= 0.02). However, 61% of the infants remained deficient despite vitamin A supplementation. Among vitamin A-supplemented infants only, diarrhea and ARI morbidity during the 3-mo period were compared in children with normal versus children with abnormal RDR at the end of the supplementation period. The ARI episodes were more frequent in the supplemented infants who remained vitamin A deficient at the end of the 3 mo (P = 0.027). Also, the cumulative duration (days, mean +/- SD) of fever and cough was 5.0 +/- 2.8 in the normal versus 11.2 +/- 6.0 in the deficient group (P = 0.04). The results of this study suggest that a large proportion of infants remain vitamin A deficient even after large dose vitamin A supplementation because of frequent respiratory infections, particularly those accompanied by fever.

Cross-validation of fat-free mass estimated from body density against bioelectrical resistance: effects of obesity and gender

The major purpose of this study was to examine whether estimates of body composition from bioelectrical resistance were systematically biased by obesity and/or gender (using hydrodensitometry as a comparison method). We compared fat-free mass (FFM) by bioelectrical resistance (BR) using 5 equations (Lukaski, Kushner, Rising, Khaled, and Segal) to FFM by hydrodensitometry (HD) in 20 lean men, 30 lean women, 33 obese men and 22 obese women. None of the BR equations was successfully cross-validated against FFM by HD in all 4 sub-groups. The Lukaski equation significantly underestimated FFM in all 4 groups by 2.7 to 4.7 kg; the Kushner equation significantly underestimated FFM by 2.0 to 2.9 kg except in obese women; the Rising equation significantly overestimated FFM in obese women (5.3 kg) and men (2.9 kg); the Khaled equation successfully predicted FFM in all groups except obese men; and the Segal equation successfully predicted FFM in all groups except lean men. In some groups, a portion of the discrepancy could be explained by bias originating from body fat. Analysis of our data by forward regression analysis demonstrated that height2/resistance, body weight, gender and suprailiac skinfold thickness provide the most accurate estimates of FFM (R2 = 0.92; SEE = 3.58 kg) that are free of bias originating from gender and body fat. We conclude that the estimation of fat-free mass by BR is significantly influenced by gender and obesity. An alternative equation is proposed for estimating fat-free mass based on measurement of height2/resistance, body weight, gender and suprailiac skinfold thickness.

Conjunctival impression cytology fails to detect subclinical vitamin A deficiency in young children

Thirty-four asymptomatic children, ages 5-35 mo, were studied to compare the conjunctival impression cytology technique with the relative dose response test in detection of subclinical vitamin A deficiency. Conjunctival smears were collected from the infero-temporal-bulbar conjunctiva of each eye with a strip of cellulose acetate filter paper and transferred onto a glass slide. Venous blood was drawn at 0 and 5 h after administration of an oral dose of 1000 micrograms of retinol palmitate (relative dose response test). An increase in serum retinol concentration (> or = 20%) in the 5-h value was considered indicative of an inadequate liver store of vitamin A and hence subclinical vitamin A deficiency. Of the 34 children, 26 (76.5%) had moderate to severe protein-energy malnutrition. Only three children (9%) had abnormal conjunctival impression cytology, whereas 23 (68%) had abnormal relative dose response. Even more striking was the finding that only two of the 23 children with abnormal relative dose response had abnormal conjunctival impression cytology. The results suggest that the conjunctival impression cytology test has poor agreement with the relative dose response test results in assessing vitamin A status in young children. If relative dose response is considered an acceptable reference method for assessing vitamin A status, then the conjunctival impression cytology test cannot be considered a valid measure of subclinical vitamin A deficiency in this population.

Comparison of the modified relative dose response (MRDR) and the relative dose response (RDR) in the assessment of vitamin A status in malnourished children

The modified-relative-dose-response (MRDR) test and the relative-dose-response (RDR) test were compared in 49 mildly to moderately malnourished Bangladeshi children. The MRDR test had a significantly lower sensitivity, detecting only 71% of children with very low serum retinol (< or = 0.35 mumol/L) and 33% of children with low serum retinol (0.355-0.70 mumol/L) compared with 100% and 80% for the RDR test, respectively. The MRDR test showed a very strong dependency on retinol-binding protein (RBP) saturation (ie, percent saturation of RBP with retinol) compared with the RDR test. Only 3 (23%) of 13 children with RBP saturation > or = 55% but low vitamin A stores were diagnosed as abnormal by the MRDR test. This suggests that when apo-RBP concentration is limiting, as it is in malnourished children, didehydroretinol, the analog used in the MRDR test cannot effectively compete with retinol for binding to apo-RBP. Under these circumstances, the MRDR test is rendered ineffective. The possibility of increasing the sensitivity of the test by using a high dose of didehydroretinol needs to be investigated.

Determination of doubly labeled water by gas-phase Fourier transform infrared spectroscopy

Both 2H (deuterium) and 18O (oxygen 18) in isotopically enriched water have been detected by gas-phase Fourier transform infrared (FTIR) spectroscopy at 2,720 and 3,661.8 cm-1, respectively. A linear relationship between varying concentrations of each of these isotopes and their absorbance at the above frequencies indicates that gas-phase FTIR may provide a rapid and potentially less expensive approach to measure doubly labeled water in biological fluids for the estimation of energy expenditure and total body water.

Changes in body composition of malnourished children after dietary supplementation as measured by bioelectrical impedance

Body composition was measured with bioelectrical impedance in 35 malnourished children aged 24-59 mo to investigate the effect of a 3-wk feeding supplementation. Twenty children received a high-protein diet with 15% of total energy as protein, whereas 15 children received an isoenergetic standard-protein diet with 7.5% of energy as protein. Bioelectrical impedance analysis and anthropometry were done before and after 21 d of dietary supplementation. The children fed the high-protein diet gained significantly more body weight than those receiving the standard-protein diet (1.33 +/- 0.54 vs 0.88 +/- 0.47 kg, P < 0.02). The total body water and fat-free mass determined by bioelectrical impedance analysis showed that the group fed the high-protein diet increased significantly more (0.92 vs 0.58 kg) than those on the standard-protein diet (P < 0.02). Results of this study suggest that feeding a high-protein diet accelerates catch-up growth and restores the reference body composition in children recovering from malnutrition.

Changes in body composition, diet, and strength of bodybuilders during the 12 weeks prior to competition

The purpose of this study was to monitor body composition, diet, and strength in male bodybuilders (No. 6) during the 12 weeks prior to competition. Data were collected every third week and analyzed with repeated measures ANOVA (p < 0.05). Significant decreases (p < 0.01) were found in body mass (-7.3 kg) and hydrostatically determined percent fat (-5.0%), while fat-free mass showed little change. All 7 skinfold sites were reduced significantly (p < 0.01) across the 12 weeks. Ultrasound scan revealed a significant decrease in skin thickness at the biceps (p < 0.01), but no change in biceps thickness. Circumferences decreased significantly at all sites (p < 0.05) except the chest. The greatest decreases were at the waist (-6.9 cm) and hips (-4.3 cm). Maximal isometric dead-lift force decreased significantly (p < 0.05) across time (-129 N). In comparison to off-season, both higher resistance and aerobic training volumes were found during pre-competition. Nutritional analyses showed significant reductions (p < 0.05) in total kilocalories, protein, fat, and cholesterol intakes. Vitamin and mineral intakes exceeded the RDAs. The data indicate the pre-competition practices were effective in reducing subcutaneous fat stores while maintaining muscle. Finally, the onset of the pre-competition phase resulted in strength loss.

Estimation of computerized tomography derived abdominal fat distribution

Measurements of intra-abdominal fat (IAF) may be important since it is associated with numerous metabolic disorders. The relationship between computerized tomography (CT) measured fat distribution and densitometry measures was investigated in a sample of 61 male Caucasian subjects, aged 18 to 30 years with varying adiposity. Regression models were developed for estimating CT-derived fat of 40 men to estimate IAF. Two equations were developed to estimate IAF. The first used only anthropometric measures. Waist circumference and log chest ratio entered the equation and accounted for 67% of the variance. The second model included densitometry-measured percentage fat with the centred product of waist and hip circumferences, accounting for 73% of the variance. Regression equations were also developed to estimate subcutaneous fat area so that the ratio of IAF to subcutaneous fat might be estimated. Although subcutaneous fat could be estimated, the ratio between IAF and subcutaneous fat could not be estimated accurately. A validation of all regression equations developed for male subjects who also completed using a separate validation sample (n = 21). Only the studies with sample characteristics similar to those found in the validation sample validated satisfactorily. Results indicate that anthropometric and densitometry measures cannot be used to estimate CT-derived abdominal fat with precision, however they may be of value in health risk screening of individuals with high levels of IAF. Proper selection procedures with regard to age, adiposity, and morbidity must be used.

Determination of total body water by deuterium NMR

A new deuterium nuclear magnetic resonance (2H NMR) method is described for determining total body water in humans. The method has been validated against a standard infrared absorption (IR) procedure using a tracer dose of deuterium oxide (2H2O) of approximately 10 g for each human subject. The precision and accuracy for the methods have been compared and found to be very similar. The advantages of the 2H NMR method over other presently available techniques that are based on 2H2O dilution are as follows: it is fast, accurate, needs only a small dose of 2H2O, can be done using any body fluid, and, most importantly, does not require any sample preparation.

Association of folate molecules as determined by proton NMR: implications on enzyme binding

The self-association in aqueous solution of folic acid (FA), 7,8-dihydrofolic acid (DHFA) and 5,6,7,8-tetrahydrofolic acid (THFA) has been studied by the use of proton magnetic resonance (1H NMR) spectroscopy. At concentrations below 10 mM, all three folates exist in (monomer)2 in equilibrium dimer equilibria with association constants (Ka) equal to 400, 66 and 14 M-1 for FA, DHFA and THFA respectively. These values decreased markedly to 157, 18 and 3 M-1, for FA, DHFA and THFA respectively, in the presence of 0.8 M KCl. The high extent of dimerization of FA is believed to impede the interaction with the active site of dihydrofolate reductase (DHFR) rendering it a poor substrate. In contrast, the DHFA with a much lower Ka is a better substrate. Conditions that lower the Ka of both FA and DHFA, (i.e., 0.8M KCl) turn them into better substrates. Based on the findings of the present study, it is also predicted that dihydro MTX may be a better inhibitor of DHFR than MTX.

2,4-Diamino-6-(bis-2-chloroethyl)aminomethyl pteridine

2,4-Diamino-6-(bis-2-chloroethyl)aminomethyl pteridine has been synthesized and found to be highly potent against L-1210 mouse leukemia lymphoblasts. A single dose of 5 mg/kg injected 24 h after the tumor inoculation increased the life-span of 50% of mice to more than 200%, while the other 50% of animals were cured.

Binding constants of phenylalanine for the four mononucleotides

Earlier work has shown that several properties of amino acids correlate directly with properties of their anticodonic nucleotides. Furthermore, in precipitation studies with thermal proteinoids and homopolyribonucleotides, an anticodonic preference was displayed between Lys-rich, Pro-rich and Gly-rich thermal proteinoids and their anticodonic polyribonucleotides. However, Phe-rich thermal proteinoid displayed a preference for its codonic nucleotide, poly U. This inconsistency seemed to be explained by a folding in of the hydrophobic residues of Phe causing the proteinoid to appear more hydrophilic. The present work used nuclear magnetic resonance techniques to resolve a limited question: To which of the four nucleotides does Phe bind most strongly? The results show quite clearly that Phe binds most strongly to its anticodonic nucleotide, AMP.

The case for the anticode

The present paper will focus on the developments in our lab related to the origin of the code since the Israel meeting (1,2). Principally these items are: (a) a new set of correlations (3) which include ranked hydrophobicities of amino acids and dinucleotides; (b) binding constants (4) of Phe for the four mononucleotides; and (c) binding constants (5) of Phe, Leu, Ile, Val, and Gly for polyadenylic acid (poly A). The data continue to support a model for the origin of the code based on relationships between amino acids and their anticodons.

Complexes of polyadenylic acid and the methyl esters of amino acids

This report includes studies of the binding of the methyl esters of a series of amino acids to polyadenylic acid. The principal data were obtained using proton NMR; however, some additional data were obtained through the study of insoluble complexes and through ultraviolet spectroscopy. The binding constants are in the order Phe greater than Ile greater than or equal to Leu greater than Val greater than Gly, and show a direct correlation with the hydrophobicities of the amino acids. In most cases they are essentially double the binding constants found by Reuben and Polk (1980) for monomeric AMP. All of these amino acids, except Gly, have A as the middle letter of their anticodons, and Phe is the only one with XAA as its only anticodon. It has the anticodon richest in A and has the highest binding constant for A. These results, coupled with other data, continue to support a model of the origin of the code which is based on weak, but selective affinities between amino acids and their anticodons.

Solution and ion-complexed conformations of beauvericin determined by proton magnetic resonance spectroscopy

The conformational properties of the cyclohexadepsipeptide antibiotic Beauvericin have been investigated by 1H-NMR spectroscopy in polar (C2H3O2H) and non-polar (CCl4, C62H6, C2HCl3) solvents and in two solvent mixtures; one a mixture of a polar and non-polar solvent (C2H3O2H/CCl4) and the other an aromatic solvent in a non-polar environment (C62H6/CCl4). The ion-complexation properties of Beauvericin with alkali metal halides (Li+, Na+, K+, Cs+) have also been studied. It is demonstrated that changes in chemical shifts of Beauvericin with concentration, with polarity of solvent or with added alkali metal ion reflect changes not only in the solvent properties but also changes in backbone conformation and changes due to ion-complexation, where appropriate, and therefore cannot be used, by themselves, to determine the conformation of the molecule, its self-aggregation properties, or the stoichiometry of the metal ion-complex. The backbone conformations of Beauvericin in different environments are determined by methods that are independent of chemical shift analysis; i.e., by measurements of 5J(HH) magnitudes observed between the alpha-CH protons of the L-phenylalanine and D-hydroxyisovaleric acid (DHyIv) residues and by nuclear Overhauser effect measurements observed between alpha-CH(HyIv) and (N)-CH3(Phe) proton signals. In the knowledge of these results the chemical shifts of Beauvericin in different environments can then be rationalised. It is found that the conformation of Beauvericin in a polar solvent is different from that found in a non-polar solvent and from that found for the in the ion-complexed form is similar to that found in non-polar solvents. By taking into account the conformational properties of the L-phenylalanine and DHyIv side-chains, it is possible to assign unambiguously the magnetically non-equivalent beta-CH2(Phe) and gamma Me(HyIv) proton signals and so elucidate the complete conformational behaviour of the uncomplexed forms of Beauvericin in a polar and a non-polar environment, and of the ion-complexed form of Beauvericin in a polar solvent.

Conformation characterization of cyclopentapeptide, L.Val-L.Pro-Gly-L.Val-Gly: a repeating analogue of elastin

The cyclopentapeptide, L.Val1-L.Pro2-Gly3-L.Val4-Gly5, was synthesized and its conformational characterization was carried out using n.m.r. and theoretical energy calculations. The n.m.r. studies indicated the existence of a cis Val1-Pro2 peptide bond in water and a very strong intramolecular H-bond between the val1 NH and Gly3 C=O groups. This H-bond forms a beta-turn (type II) placing Val4 and Gly5 residues within the turn. Two minimum energy conformations were derived, one of which agrees very well with the solution conformation.

15N-NMR of repeat peptides of tropoelastin. The tetrapeptide

The 15N-NMR data obtained in chloroform and methanol are reported for Boc-L-Val1-L-Pro2-Gly3-Gly4-OMe, a repeat tetrapeptide sequence of tropoelastin. Deuterium substitution for labile peptide protons was carried out to delineate solvent-exposed and solvent-shielded peptide nitrogens. Solvent perturbation of the peptide nitrogen resonances together with the hydrogen-deuterium substitution reaffirms the previously derived conformation of the molecule in chloroform which contains a beta-turn (type II) and a 14-membered hydrogen bond to form a cross-beta structure.

Rate theory calculation of gramicidin single-channel currents using NMR-derived rate constants

By means of 23Na NMR, two ion binding sites were observed in phospholipid-packaged gramicidin channels and the four associated rate constants were approximated. Limits also were placed on a fifth rate constant for an intrachannel ion translocation. By using Eyring rate theory to introduce voltage dependence, these rate constants were used in steady-state-current equations for calculation of gramicidin single-channel currents for two- and three-site models. Calculated single-channel currents are compared with previously published experimental single-channel currents obtained by electrical measurements on Na+ transport across gramicidin-doped planar lipid bilayers. The calculated results for the two- and three-site models compare favorably with the experimental results. Accordingly, it is demonstrated that NMR-derived rate constants can be coupled with Eyring rate theory to calculate currents through a transmembrane channel and to do so within levels of variation that compare with the differences obtained on planar lipid bilayers formed with different lipids.

Nuclear magnetic resonance studies on a cyclic dodecapeptide analogue of a repeat hexapeptide of tropoelastin: evaluation of secondary structure

The cyclododecapeptide, (Ala1-Pro2-Gly3-Val4-Gly5-Val6)2, was synthesized and its secondary structure was evaluated from extensive studies in dimethyl sulphoxide, trifluoroethanol and water using NMR methods. A selective decoupling technique in 13C-NMR has been utilized in order to assign the C=O carbon resonances. Temperature dependence of the peptide NH protons and the solvent perturbation of the peptide NH and C=O resonances show the occurrence in all solvents of a beta-turn (a 10-membered H-bond between the Val4 NH and Ala1 C=O) and a gamma-turn, an 11-membered H-bond between the Gly3 NH and the Gly5 C=O; and a possible 14-membered H-bond between the Ala1 NH and the Val4 C=O in dimethyl sulphoxide and trifluoroethanol. These secondary structural features are compared with the linear polyhexapeptide and found the the beta-turn and the gamma-turn are the common conformational features of these peptide systems.

Proton magnetic resonance and conformational energy calculations of repeat peptides of tropoelastin. A permutation of the hexapeptide

The conformation of a hexapeptide sequence occurring in tropoelastin is discussed from the results obtained using a combined approach of theoretical conformational energy calculations on HCO-Val-Ala-Prb-Gly-OMe and 1h nmr studies on t-Boc-Val-Ala-Pro-Gly-Val-Gly-OMe in a dilute solution of methanol. Both studies have reasonable concurrence with respect to the preferred conformation of the hexapeptide and an analysis of the combined results suggests that the hexapeptide is stabilized by a beta-turn involving the Ala1,iC=O and Val4,iNH groups and a gamma-turn involving Gly5,iC=O and Gly3,iNH groups. A weaker interaction between Gly3,iC=O and Gly5,iNH groups is also found to be possible. Conformational features of the first valyl residue in the sequence Val-Ala-Pro-Gly-Val-Gly and the last valyl residue in Ala-Pro-Gly-Val-Gly-Val are compared and found to have similar torsion angles. The implications of such a similarity are discussed with respect to the conformation of the polyhexapeptide.