An Analysis of the Protein and Lipid concentrations in the Tear Layer of Contact and Non-contact lens wearers

Purpose: The main reason for embarking upon this specif aspect of the study is to obtain local population statistics in Trinidad, W. I. Most of the research pertaining to the tear layer has been done internationally with statistical analysis stemming from the Wester World. The clinical significance of this study is to provide early means of detection of primary and secondary diseases such as hpyerliproteninemia, dyslipdemia, and triglyceridemia in human population. The significance is to determine the relationship between a contact lens wearer and individual components (total proteins and total lipids) of their tears. This is to examine the tear-lens relationship between the disposition of components of the tear film on soft (hydrogel and silicone hydrogel) contact lenses in relation to lens intolerance, patient discomfort and dry eye syndrome. Method: A total of 93 subjects were interviewd and tear samples were obtained from 81 participants. The capillary tube technique was used to extract tear fluid samples and were stored at -80 degrees celsius. Total Protein and Triglyceride Liquicolour kits were used to analyse tears. Using a mass spectrometer, absorbance values were used to calculate the total proteim and total triglycerid concentrations for non-contact lens and contact lens wearers. Results: It was formulated that the total concentrations of proteins and lipids in the tear film of non-contact lens patients were 7.356 1.31 and 3.76 3.26 mg/dl. The protein and lipid concentrations of contact lens patients were determined; these results were 5.88 0.91 and 2.54 0.72mg/dL. Conclusion: Based on independent statistical analysis, there was no sigificant difference between the protein and lipid concentrations of non-contact lens patients. There was also found to be no significant difference between contact lens and no-contact lens wearers' protein and lipid concentrations.

Determination of RBC membrane and serum lipid composition in Trinidadian type II diabetics with and without nephropathy.

AIM: The rheological properties of erythrocytes are impaired in diabetes mellitus, especially because of changes in their membrane lipid composition.The aim of this study was to determine and examine the relationship between red blood cell (RBC) membrane and serum lipid composition in type II diabetes subjects with and without nephropathy. METHODS: Trinidadian subjects aged 18-65 years were recruited for the study regardless of gender and ethnicity. Fasting blood samples were collected from 60 subjects of whom 20 were healthy individuals, 20 had type II diabetes without complications, and 20 were type II diabetics with nephropathy. Weight, height, waist/hip ratio, and blood pressure were recorded. All the blood samples were analysed to determine the serum lipid concentration, membrane lipid composition and plasma glucose concentration. RESULTS: The body mass index and the systolic blood pressure of the diabetics (28.17 +/- 4.98 kg/m2, 153.21 +/- 22.10 mmHg) and those with nephropathy (25.87 +/- 4.68, 158.60 +/- 22.49 mmHg) were higher when compared with controls (24.67 +/- 5.18, 119.15 +/- 13.03 mmHg). The diabetic (175.89 +/- 102.73 microg/mgprotein) and diabetic nephropathy (358.80 +/- 262.66) subjects showed significantly higher levels of RBC membrane cholesterol compared with controls (132.27 +/- 66.47). The membrane phospholipids, protein and Na+/K+ATPase concentrations were altered in diabetics and diabetic nephropathy patients when compared with controls. The trends of increased serum cholesterol and decreased high-density lipoprotein in diabetics and diabetic nephropathy patients were noted as compared with controls but they are not significant as expected. The low-density lipoprotein cholesterol was significantly higher in diabetics when compared with diabetic nephropathy and control subjects.

Leptin and body composition of Nigerians, Jamaicans, and US blacks

The role of leptin in humans remains controversial. Leptin concentrations are highly correlated with body fat stores. We tested whether or not this relation was consistent across the range of body composition encompassing the lean as well as the obese. Individuals participating in community-based comparative research in Nigeria (n = 363), Jamaica (n = 372), and the United States (Maywood, IL; n = 699) had their plasma leptin concentrations and body compositions (with bioelectrical impedance analysis) measured. All participants identified themselves as being black. Body mass index (in KG/m2) ranged from across populations for both men and women in Nigeria, Jamaica, and the United States, respectively (men: 2.8, 3.9, and 6.8 microg/L; women: 10.3, 18.6, and 27.7 microg/L). An exponential function fit the relation between percentage body fat or total fat mass and leptin for men and women at each site. For women and men the exponential function with either percentage body fat or total fat mass was of the same shape, but increased by a constant in women, yielding higher leptin concentrations than in men at every level of body fat. On the basis of this broad distribution of body composition, the data suggest an exponential response of leptin to increase in body fat stores, consistent with the development of leptin resistance in individuals developing obesity. These findings likewise confirm that men and women exhibit different set points in terms of leptin production(AU)

Leptin concentration in women is influenced by regional distribution of adipose tissue

Leptin concentration in humans are increase with obesity, and women have higher leptin concentration than men. This sex difference reflects the greater fat mass of women. However, there is evidence that factors other than the size of the adipose tissue mass contribute to serum leptin concentrations. This study was undertaken to determine whether anthropometric factors influenced leptin concentrations in our population. Leptin concentrations were measured in 375 persons from a population study of hypertension and diabetes for whom body-composition data (bioelectrical impedance analysis and anthropometry) were available. Serum leptin concentrations were more than four times higher in women than in men (18.5 ñ 13.9 compared with 3.8 ñ 3.5 ng/L, P < 0.0001). In individuals with comparable body mass indexes, these differences persisted after adjustment for either percentage fat (P < 0.05) or fat mas (P < 0.0001) by multivariate-regression analysis. After fat mass was adjusted for, the serum leptin concentration in both men and women was independent of waist circumference but in women was associated with hip circumference. Hip circumference is a proxy measure of peripheral fat and these results suggest that the larger hips of women may contribute to the sex difference in serum leptin concentration.(AU)

The effect of splenectomy for hypersplenism on whole body protein turnover, resting metabolic rate and growth in sickle cell disease

OBJECTIVE: To determine whether, in the same individual, an observed fall in whole body protein turnover following splenectomy in children with hypersplenism and homozygous sickle cell (SS) disease is associated with a measurable fall in resting metabolic rate (RMR) and an increase in rate of growth. SUBJECTS: Six children (5 SS disease, 1 S beta degree thalassaemia), aged 68 to 126 months, were studied before and after splenectomy for hypersplenism. DESIGN: Protein turnover was measured by the end product method using prime/intermittent oral doses of 15N-glycine and RMR by indirect calorimetry before preoperative transfusion and repeated at least eight weeks after splenectomy. Height and weight velocities were measured over six month periods before and after splenectomy. SETTING: University Hospital of the West Indies in Jamaica and the Medical Research Laboratories (Jamaica). RESULTS: After splenectomy protein turnover fell significantly by 30 percent and RMR by 34 kJ/kg/d. Mean weight velocity which was below normal before surgery, z = -2.3, improved significantly after surgery, z = 0.7, (p = 0.03). Height velocity increase in two children but the mean height velocity did not change following splenectomy. The reduction in protein turnover was estimated to account for 62 percent of the fall in RMR. CONCLUSION: This study confirms that there is a significant reduction in energy expenditure following splenectomy for hypersplenism in SS disease. A reduction in protein turnover was a major contributor to the saving in energy, although it is not clear whether it accounted for all. In the present group of children the energy saved was associated with an improvement in the wasting present before splenectomy.(AU)

Malnutrition of children in developing countries: what can we do?

This informal paper is a personal account of the development of my work on malnourished children, starting with clinical studies in Jamaica and the challenge of an unacceptably high mortality rate; moving on to the problem of how to define less severe malnutrition in the community; and ending with some reflections on the enormously difficult question of prevention and the contribution that richer countries such as the UK could make (AU)

The effect of splenectomy on whole body protein turnover in homozygous sickle cell disease

In individuals with homozygous sickle cell (SS) disease, haemolysis creates a demand for increased red cell production. In children with hypersplenism haemolysis may be further increased and in such cases the excessive red cell production may be reduced by splenectomy (1). Whole body protein turnover is increased in SS disease and a large part of this increase is the consequence of increased turnover of red blood cells (2). Whole body protein turnover has therefore been measured in children with SS disease before and after splenectomy to find out if the reduction of the haemolytic rate following splenectomy was associated with a decrease in protein turnover. (AU)

Whole body protein turnover and resting metabolic rate in homozygous sickle cell disease

Whole body protein turnover and resting metabolic rate were measured in six adults with homozyguous sickle cell disease (genotype HbSS) and in six normal adults (genotype HbAA) of similar age. Turnover was measured with prime/intermittent oral doses of [15N]glycine over 18 h and resting energy expenditure was measured by indirect calorimetry. In HbSS, nitrogen flux (0.9 ñ 0.08 g day-1 kg-1), protein synthesis (6.0 ñ 0.5 g day-1 kg-1) and protein degradation (5.6 ñ 0.5 g day-1 kg-1) were significantly increased compared with HbAA nitrogen (flux 0.5 ñ 0.02g day-1 kg-1, protein synthesis 3.2 ñ 0.2 g day-1 kg-1 and protein degradation 2.8 ñ 0.2 g day-1 kg-1). Resting energy expenditure was significantly higher in HbSS compared with HbAA when expressed per unit of body weight (115 ñ 3 and 94 ñ 4 kj day-1 kg-1 respectively) or weight 0.75(317 ñ 6 and 269 ñ 8 kj day-1kg-0.75, respectively). The increase in protein turnover and energy expenditure suggest that patients with HbSS exist in a hypermetabolic state that requires greater dietary energy compared with HbAA. (AU)

Whole-body protein turnover in man determined in three hours with oral or intravenous 15N-glycine and enrichment in urinary ammonia

Studies were carried out in eight normal adults to simplify the continuous infusion-end product method for measuring whole-body protein turnover using 15 N-glycine. When a priming dose of label suitable for the urea pool was followed by intermittent oral doses of label, plateau enrichment was maintained in urinary urea and ammonia from 9 to 18 h, giving values for nitrogen flux. (18h) of 0.69ñ0.05 g N/kg/d with urea and 0.46ñ0.01 g N/kg/d with ammonia. With a priming dose appropriate for the ammonia pool, plateau was reached in urinary ammonia in less than 120 min an maintained for up to 6h. Nitrogen flux (3h) with oral 15N-glycine was 0.96ñ0.12 g N/kg/d, and with intravenous label was 0.61ñ0.13 g N/kg/d. There was a significant linear relationship between flux measured with oral and intravenous isotope. It is suggested that different components of protein turnover are measured with the different approaches, and that the short method in particular measures rapidly turning over proteins associated with the gastrointestinal tract.(AU)

Whole body protein turnover and basal metabolic rate in homozygous sickle cell disease - abstract

Nitrogen balance and isotopic studies have indicated that protein metabolism in HbSS is altered. This is associated with the increased turnover of protein haemoglobin. We have therefore investigated protein matabolism in 6 patients with HbSS and 6 subjects with normal haemoglobin genotype (HbAA) by measuring and comparing whole body protein turnover (WBPT). Basal metabolic rate (BMR) was also measured as there is evidence that WBPT and BMR change in the same direction in various physiological and pathological states. WBPT was measured with an oral primed intermittent infusion of 15N-glycine over 18 hrs on an intake of 0.8-1.2g protein kg(to-1 power) d(-1power) and 187-193kJ kg(to -1 power) d(-1 power). Enrichments in urinary urea and ammonia were used to calculate turnover. BMR was measured by oxygen consumption using a ventilated hood system. Turnover in HbSS subjects was 66-81 percent more than in normal subjects. There were increases in both synthesis and breakdown. BMR was increased by 7 percent in the HbSS subjects compared to normal: the difference was even greater when the results were expressed in terms of body weight (22 percent) and muscle mass (20 percent). Assuming that all the increase in BMR resulted from the increase in turnover, we calculated that as much as 40-44 percent of BMR was consumed by protein turnover in patients with sickle-cell disease compared to 27-32 percent in th normal subjects. The results suggest that patients with Hbss have a hyper-metabolic state in which the demand for energy is greater than normal. Inadequacy of the standard normal diet may therefore be related to the poor growth usually seen in HbSS. Furthermore, the calculated high-energy cost of protien turnover in the patients with sickle-cell disease compared to normal suggest that patients with HbSS are less able to tolerate a reduction in dietary energy. This may help to explain their lowered resistance to stress and trauma, their poor wound healing and their high susceptibility to infection (AU)

Studies of whole body protein turnover within three hours in man using 15 N-glycine as tracer and urinary ammonia as end-product - abstract

We have been investigating ways in which to simplfy the method for measuring proteing turnover, by shortening the time required for reliable measurements. It has been possible, using 15N-Glycine and urinary ammonia as the end-product, to measure turnover in two to three hours in normal man. Turnover was calculated following either oral or continuous infusion of 15N-Glycine (0.005 15N/kg/h) in 8 adult men. Plataeu was reached within 120 minutes and was maintained for at least 4 to 6 hours. The results were as follows: AMMONIA ENRICHMENT: Oral dose - turnover (mgN/kg/D) 960ñ128 (SD), synthesis (gPr/kg/D) 4.7ñ0.7, breakdown (gPr/kg/D) 4.9ñ0.8; AMMONIA ENRICHMENT: I.V. dose turnover - (mgN/kg/D) 608ñ128, synthesis (gPr/kg/D) 3.1ñ0.8, breakdown (gPr/kg/D) 2.8ñ0.8. There was a significant linear relationship between ammonia enrichment (oral) and ammonia enrichment (I.V.) (R=0.82; p<0.05). In the same group, turnover measured from ammonia enrichment over 18 hours was 450 ñ 30mg N/kg/D. Turnover measured over 3 hours thus gave higher values than measurements over 18 hours; this is probably because more proteins with shorter half-lives are included in the 3 hour measurements. This would imply that previously reported measurements which used the longer measurement period underestimated turnover by at least 50 percent, and hence significantly underestimated the contribution of protein turnover to basal energy expenditure. The (3 hr) oral measurement appears to measure flux through a pool not included in the measurement intravenously. As this is of a similar magnitude to the pool into which hydrolysed urea nitrogen passess (Jackson et al, Hum. Nutr. Clin. Nutr., 38C, 339, 1984) it may represent a distinct enterohepatic pool of metabolic nitrogen (AU)

Whole-body protein turnover in Jamaican women during normal pregnancy

A cross-sectional study was carried out among 18 Jamaican pregnant women divided in three groups of 6 subjects according to the stage of pregnancy: group B, 12 weeks, group C, 24 weeks and group D, 33 weeks. A group (group A) of 6 non-pregnant women was selected as control. The rate of whole-body protein turnover was measured by continuous oral administration of 15N-glycine and the resting metabolic rate by the open circuit method. All subjects had a normal pregnancy outcome. The composition of the diet on the day of the study was comparable between the four groups (approximately 80 g protein and 9.45 MJ energy) and not significantly different from the composition of the diet during the 2 d prior to the experiment. The rates of protein synthesis and breakdown were higher in groups Band C compared to group A and lower in group D where they reached values slightly higher than in group A. Estimated from urea enrichment, these rates did not vary significantly among the groups, while estimated from ammonia enrichment the difference was significant (P less than 0.05) and there was a negative correlation between the gestational age and the rate of snythesis (r= -0.63) and breakdown (r= -0.69). Nitrogen retention was comparable between the three groups of pregnant women and significantly higher than in the group A. The resting metabolic rate was similar between the groups of pregnant women. These results suggest that the rates of protein turnover observed during gestation reflect more the changes that occur in maternal than those in fetal tissues. The values for protein synthesis and nitrogen retention indicate that the amount of protein deposited during pregnancy is greater than that expected on the basis of body composition analysis. It is also suggested that as pregnancy proceeds whole-body protein turnover represents a smaller part of the resting metabolic rate. (AU)

The use of 15 N-alanine as a tracer to measure whole body protein turnover (WBPT) in man - abstract

A preliminary study was designed to determine the most suitable metabolic condition (fed, fasted) and appropriate time (day, night) to measure whole body protein turnover. A primed intermittent oral dose of the tracer was given; urinary ammonia and urea were used as end-products. With feeding, an isotopic steady state was maintained but upon withdrawal of food it was disrupted. Also, as fasting progressed, the enrichment in urinary ammonia and urea kept increasing. This indicates that alanine did not seem to be a good tracer to measure WBPT under metabolic conditions, where the intake of food was not constant. In the fed state, rates of WBPT were measured after a primed, intermittent oral dose and after a primed, continuous intravenous infusion. Six subjects were used in the oral study and two of the six subjects were chosen for the intravenous study. During the oral administration, mean rate of WBPT as measured by the enrichment in urinary ammonia and urea, was found to be 2.25 ñ .2 gm protein/kg/day and 3.00 ñ .4 gm protein/kg/day respectively. The value obtained from the intravenous study was 1.87 gm protein/kg/day with ammonia and 4.57 gm protein/kg/day with urea. The results show that, within studies estimates of protein flux from ammonia and urea generally were not comparable, oral doses gave higher estimates with ammonia whereas the intravenous dose gave higher estimates with ureas. In contrast with the most commonly used tracer (15 N-glycine), 15N-alanine gave estimates that were lower when the respective technique and end product was considered. However, the rank order of these values for the different method was similar to those with 15 N-glycine (AU)

Whole-body protein turnover and nitrogen balance in young children at intakes of protein and energy in the region of maintenance

Nitrogen balance and whole-body protein turnover were measured in children aged about one year taking diets which provided 1.7 or 0.7 g milk protein/kg/d at three levels of metabolizable energy, 80, 90 and 100 kcal/kg/d. All the children were in positive nitrogen balance at all levels of energy intake on 1.7 g protein/ kg/d. Nitrogen equilibrium was maintained on 0.7 g protein/kg/d when the energy intake exceeded 90 kcal/kg/d, but on 80 kcal/kg/d nitrogen balance was negative. Whole-body protein turnover was measured from the enrichment in urinary ammonia following a continuous infusion of15N-glycine. The variation between individuals on the same diet was significantly greater than the variation within individuals at different levels of energy intake. For the group as a whole protein synthesis on 1.7 g protein/kg/d was 0.74, 0.75 and 0.87 g N/kg/d on 100, 90 and 80 kcal/kg/d respectively;whereas on 0.7 g protein/kg/d it was 0.37, 0.38 and 0.40 g N/kg/d. These results show that over this range of intakes protein synthesis decreased as dietary protein fell, but tended to increase as energy intake fell. (AU)

Studies of 15N-alanine metabolism in man: estimation of whole body protein turnover rates, alanine flux, de novo synthesis of alanine contribution to urinary ammonia

A primed intermittent oral dose and a primed continuous intravenous infusion of 15N-alanine was administered to healthy males to determine the rates of protein turnover, synthesis and breakdown. The subjects were fed an adequate intake throughout the day. Urine and blood samples were collected. Mean rate of protein flux as measured by the enrichment of urinary ammonia and urea were found to be 2.25ñ.21 and 3.00ñ.42 g. protein/kg./day respectively during the total administration. The values obtained from the intravenous study were 1.87 g. protein/kg./day with ammonia and 4.57 g. protein/kg./day with urea. When each end product and the respective technique was considered the mean rate obtained using 15N-alanine was lower than that reported using 15N-glycine. However, the rank order of the values for the different methods was similar to those with 15N-glycine. Mean plasma alanine flux after the oral and intravenous studies were 548 ñ128 and 281 æmol/kg./hr. respectively. Red cells alanine flux was different and higher than plasma flux in each study. During the studies a considerable amount of label was transferred to urinary ammonia and urea while glutamate and alanine had low enrichments. In the fed state, after the oral dose, de novo alanine synthesis was calculated to be 457.4 æmol/kg./hr. This accounted for eighty-three percent of plasma alanine flux, thus seventeen percent of alanine moving through the venous plasma compartment originated from performed alanine. Up to sixteen to twenty-two percent of urinary ammonia was derived from alanine (Summary)

Glutamine production rate and its contribution to urinary ammonia in normal man

Glutamine [15N]amide was infused at a steady rate of 33.34 micromoles/h into seven male adult volunteers who were in the fed state and normal acid-base status. Plasma glutamine amide N enrichment and urinary ammonia N enrichment rose to a constant value within 3h. The glutamine production rate was 51.8 ñ 7.9 millimoles/h. The total ammonia execretion rate was 0.87 millimoles/h. Of this excreted ammonia 62.6 ñ 9 percent was derived from the amide N atom of glutamine. The excreted glutamine amide N (0.53 millimoles/h) was only 1 percent of the glutamine production. If half the ammonia formed by the kidney is excreted in urine and half liberated into the renal vein in subjects with normal acid-base status [E. E. Owen & R. R. Robinson (1963) Journal of Clinical Investigation, 42, 263-276], then the kidney accounts for only 2 percent of glutamine disposal. Whole body protein turnover, measured from the urinary [15N]ammonia enrichment, was 30.3 ñ 7.7 g of N/day (2.8 g of protein/day/kg). (AU)

Nitrogen metabolism in preterm infants fed human donor breast milk: the possible essentiality of glycine

Nitrogen metabolism was studied in three preterm infants (mean gestation 32 wk) by the method of consecutive metabolic balance. The absorption and retention of nitrogen from breast milk was measured, and protein turnover, synthesis, and breakdown were calculated from isotopic plateau of urinary urea and ammonia using an intermittent oral administration of 15N-glycine. Weight gain and nitrogen retention were compared with the weight gain and nitrogen accumulated for a foetus of equivalent gestational age in utero (AU)

Farming, family life and nutrition in Allsides Trelawny - six case studies

The aims of this study were: 1) To compare the output of energy and protein from experimental plots with that from farmers practising traditional farming methods in a rural district. 2) To examine the food consumption patterns of some farm families. The study took the form of six case studies of farm families. These families were visited on a regular basis for a six-month period. Twenty-four hour dietary recalls were obtained, and information on food expenditure collected. Yield data was collected both from the experimental plots as well as from the farmers. Anthropometric data was also collected on some children. The result indicated that 11 families had deficit intakes of energy compared to their RDA. These ranged from 50 percent to 78 percent . All families except two had intakes of protein in excess of the RDA. Four out of the six families spent more than their estimated weekly income from farming on food. The most striking feature of the families' diets was the monotony - yam being the major source of carbohydrate, and often being eaten three times for the day. There was a great dependence on tinned foods (especially mackerel) to provide variety in the diets. The yield data from the experimental plots indicated the potential of some of the cropping systems for improving the nutrient output of the farmers (Summary)

Nutrition and protein turnover in man

The composition and homoeostasis of the body are maintained by the integrated action of all the tissues and organs. Therefore, although it is of interest to look at the component parts separately, each part has to be fitted functionally into a greater over-all framework. Whole-body protein turnover represents the integration of one fundamental activity of living organisms. Each individual protein has its own turnover rate, responding in a particular way to any change in metabolism. The turnover in the whole body is the resultant of these activities and in this sense has been likened to basal metabolic rate. The measurement of protein turnover in man has wide application, not only to the normal metabolic changes taking place during growth but also to disorders of metabolism in many clinical conditions. Although the standard nitrogen balance technique gives valuable information on net changes, it cannot indicate either the intensity of nitrogen metabolism or the mechanism by which changes are brought about. Nitrogen balance is the resultant of differences between synthesis and breakdown, which may change in the same or opposite directions in any given clinical state.(AU)