Indices of obesity derived from height and weight in a Nigerian adult population.

BACKGROUND: Obesity is a rapidly growing health risk all over the world. Even in mild degrees, it has serious adverse effects and is associated with diminished life span. The study was aimed at determining the most suitable obesity index derived from height and weight in a young adult Nigerian population. METHODS: A cross-sectional study of students of University of Nigeria Enugu Campus was done. Heights and weights of 402 males and 268 females aged between 20 and 28 were measured. Weight-height ratio (W/H), body mass index (W/H2), Rohrer's index (W/H3) and ponderal index (H/W(1/3)) were calculated. RESULTS: Zero-order correlation coefficients of these indices with height and weight showed that body mass index was the only index not significantly correlated with height in both sexes. Weight-height ratio and Rohrer's index underestimated the degree of obesity in short subjects and overestimated it in tall subjects. The reverse was the case for ponderal index. CONCLUSIONS: Body mass index (W/H2) is the most suitable index derived from height and weight for the assessment of obesity in our study population. We recommend its use in busy clinical practice and epidemiological studies.

Substitution of cardiac troponin C into rabbit muscle does not alter the length dependence of Ca2+ sensitivity of tension.

1. The isometric length-tension relationship for cardiac muscle is generally steeper than for skeletal muscle in the physiological range of sarcomere lengths. Recent studies suggest that cardiac troponin C (cTnC) may have intrinsic properties that confer greater length-dependent changes in Ca2+ sensitivity of tension than for skeletal troponin C (sTnC). We tested this hypothesis by characterizing tension-pCa (pCa is -log[Ca2+]) relationships in rabbit skinned psoas muscle fibres at mean sarcomere lengths of 2.32 and 1.87 microns both before and after partial replacement of endogenous sTnC with cTnC. 2. In untreated control fibres, the mid-point (pCa50) of the tension-pCa relationship shifted to lower pCa by 0.15 +/- 0.02 pCa units, i.e. became less sensitive to Ca2+, when sarcomere length was reduced, and the relationship became steeper. 3. Partial extraction of endogenous sTnC and reconstitution with cTnC resulted in no change in the length-dependent shift of pCa50 when reconstitution with cTnC was more than 95% complete; however, when reconstitution was less than 95% complete, there were significant increases in the length-dependent shift in pCa50. 4. An increase in the length-dependent shift of pCa50 was also observed in fibres from which sTnC was partially extracted, but no cTnC was subsequently re-added. 5. We conclude that differences in type of TnC alone are not sufficient to explain differences between skeletal and cardiac muscles in the length dependence of Ca2+ sensitivity of tension.

Body surface area of Africans: a study based on direct measurements of Nigerian males.

Direct measurement of body surface area (Ab) was made on 20 male adult Nigerians of African descent by coating and planimetry. The results were compared with estimated Ab values obtained using six widely accepted height and weight prediction equations. The results show that existing formulas do not predict surface areas of our subjects accurately. Measured Ab values of our subjects were 6-22% greater than predicted values obtained from non-African nomograms. Using these results, we computed new variables for height and weight formulas that accurately predict the surface area of Africans. The closest fit to measured values is given by the equation Ab(m2) = 0.001315 x Height 1.2139 (cm) x weight 0.2620 (kg) +/- 0.04815 (SEE). The new variables are significantly different from those of existing equations. Our height variable is several times greater than the weight variable and reflects a greater importance of height than weight in determining the surface area of Africans than is the case with Caucasians.

Evaluation of home-made salt-sugar oral rehydration solution in a rural Nigerian population.

Standardized local measures for preparing oral rehydration solution (ORS) in Nigeria were re-evaluated under laboratory conditions. Our results confirm those of the standardization team in respect of granulated and cube sugar. However, our mean weight of one salt measure (2.8155 +/- 0.292 g) is about 20% greater than their value. Consequently, correct use of the measures in our study gave solutions of 211-297 mmol-1 total concentration and 60-80 mmol-1, Na+ as against their values of 173-251 mmol 1-1 and 45-70 mmol-1, respectively. This discrepancy is most likely due to differences in salt type. Analysis of home-made solutions prepared by 40 illiterate mothers showed that 60% of them made accurately composed solutions. All the rest made hypertonic solutions. Salt type, spoon size and levelling technique are all possible causes of their error. The tendency to err only on the side of greater rather than lower salt concentration may be culture based or simply due to natural maternal instinct. To combat this trend, health education programmes in Nigeria should emphasize the danger in feeding a hypernatremic solution to a dehydrated child.

PIP: 45 mothers attending the Outpatient Clinic at Obukpa Health Center, Nsukka, Anambra State of Nigeria, were taught repeated demonstrations of how to prepare sugar-salt solutions (SSS) as part of a study designed to assess the reproducibility of the recommended method and to determine the accuracy and variability of the composition of solutions prepared by illiterate mothers after being taught the formal and technique. The mothers were asked to prepare the solution at home and to bring samples on the same day to the clinic. 40 mothers responded. the variability of the weights of 3 ml spoon measures of salt and sugar, leveled as recommended, was investigated using as many different makes of metal and plastic spoons as were commonly available in local markets. Preliminary results indicated that plastic spoons were extremely variable, and their use in the study was discontinued. 9 different makes of metal 3 ml spoons were identified. 3 measurements of salt and of granulated sugar were made with each spoon and their weights determined on a balance with 0.0001 g sensitivity. Using the mean weights of salt and granulated sugar and ingredients purchased from the local market, 9 laboratory control solutions were made by dissolving the correct amounts of salt and sugar in 650 ml of distilled, deionized water. A 10th laboratory control solution was made with the amounts of salt and sugar obtained using the mean weights for all 9 spoons. The contents of World Health Organization/UN International Children's Emergency Fund and Nigerian Federal Ministry of Health sachets dissolved in the corresponding recommended volumes of distilled, deionized water also served as control solutions. Differences between individual measurements with the same spoon were quite small -- the maximum coefficient of variation was 4.6%, an indication of the reproducibility of the leveling technique. The mean weight of 1 level spoonful of sugar was in close agreement with that of the standardization team. The man weight of 1 sugar cube was also closely identical to their result. 24 mothers (60%) prepared solutions of similar Na+ and control concentrations as the laboratory controls. The remainder all prepared hypertonic solutions. Not a single mother prepared a solution hypotonic or hyponatremic with respect to laboratory control solutions. Possible causes of the error are salt type, spoon size, and leveling technique. The tendency to err only on the side of greater rather than lower salt concentrations may be culture based or simply due to "maternal instinct." Health education programs in Nigeria should emphasize the danger of feeding a hypernatremic solution to a dehydrated child.

Energetics of isometric contraction in dystrophic fast and slow muscles.

The amount of phosphoryl creatine (PC) hydrolysed during a ten-second isometric contraction was measured in the biceps brachii (fast) and soleus (slow) muscles of adult normal and dystrophic mice (Re 129 strain) following inhibition of glycolysis and oxidative phosphorylation. The dystrophic muscles were found to have a lower isometric economy (tension-time integral per mumol PC) than the normal muscles. This was particularly so in the case of the fast biceps brachii muscle which is affected by dystrophy to a greater extent than the slow soleus muscle. The isometric economy of the dystrophic muscles was lower even when the results were based on a total creatine rather than on a weight basis. This suggests there may be some defect in the contractile proteins of dystrophic muscle. The normal soleus muscle was found to be approximately three times more economical in maintaining tension than the normal biceps brachii muscle. This indicates the adaptation of slow muscles such as the soleus are used for maintenance of posture.

Biochemical efficiency and intrinsic shortening speed in selected vertebrate fast and slow muscles.

The biochemical efficiency was measured in iodoacetate N2 and NaCN-treated muscles by dividing the work done by the amount of phosphoryl creatine hydrolysed when contracting at their optimum velocity. An inverse relationship was found between the intrinsic speed of shortening (Vmax) of the muscles and their mechanochemical efficiency.