Asymmetric synthesis of gamma-hydroxy alpha,beta-unsaturated aldehydes via enantioselective direct addition of propargyl acetate to aldehydes.

We report the first example of enantioselective and diastereoselective aldehyde additions of propargyl acetate to aldehydes using the methodology recently reported from our laboratories. Subsequent O-silyl protection, Pd-catalyzed isomerization, AcOH addition, and hydrolysis result in optically active gamma-hydroxy alpha,beta-unsaturated aldehydes as powerful building blocks. Reaction: see text.

Suitability of air sampling locations downstream of bends and static mixing elements.

The revised standard for sampling effluent air from stacks and ducts of the nuclear industry places limits on the non-uniformity of velocity and contaminant profiles at the sampling location; namely, the coefficients of variation must not exceed 20% over an area that encompasses at least the center 2/3 of the cross sectional area. Tests were conducted to characterize the degree of mixing at downstream locations as affected by several types of flow disturbances, including 90 degree elbows and commercial static mixing devices. Flow straighteners were incorporated into the ducting upstream of the mixer to be tested to simulate the dampening of flow turbulence that might occur because of upstream HEPA filters. The coefficients of variation of velocity and tracer gas concentration measured in a straight tube at a distance of 3 diameters downstream from a 90 degree elbow were 17% and 69%, respectively. The mixing is impacted by the upstream flow turbulence. Without a flow straightener, the tracer gas concentration coefficient of variation was reduced to 33% at the 3-diameter location. The use of static mixing elements can greatly enhance the mixing process. A ring placed just downstream of a 90 degree elbow, which blocks the outer 56% of the cross sectional area, results in a coefficient of variation of 19% for tracer gas concentration at the 3-diameter location. Pressure loss across the elbow with the ring is about nine times that of the basic elbow. One of the commercially available static mixers provides coefficients of variation that are less than 10% for both velocity and tracer gas concentration at 4 diameters downstream from the mixer with a pressure loss that is only about 3.5 times as large as that of a 90 degree elbow.

A generic mixing system for achieving conditions suitable for single point representative effluent air sampling.

The U.S. EPA has approved Alternate Reference Methodologies for sampling radionuclide aerosol particles from stacks and ducts of U.S. DOE facilities. The approach allows use of single point sampling with shrouded probes from locations where both fluid momentum and contaminant concentration are well mixed across the flow cross section. For existing stacks and ducts that do not have locations where there is adequate mixing, we have developed a generic mixing system that will generate conditions suitable for single point sampling. The coefficients of variation of the velocity, tracer gas, and 10 microm aerodynamic diameter aerosol particles profiles are all less than 10%, which are well within the EPA limit of 20%. Mixing is affected neither by size of the system nor by flow rate, provided the flow is turbulent.

Nutrient absorption from a fat-enriched diet in young malnourished children: a randomized controlled trial.

A randomized, controlled trial was undertaken to compare nutrient absorption from low fat (22.2% energy as fat) and high fat (48% energy as fat)-containing mixed diets in 39 (26M, 13F) malnourished children aged < 2 y. Subjects of both dietary groups, standard (SDG, n = 18) and experimental (EDG, n = 21), were offered 184.5 ml of feeds/kg body weight/24 h that provided 146 kcal with the low fat diet and 216 kcal with the high fat diet, respectively. The baseline clinical and biochemical parameters and the volume of feeds consumed by the patients in the two groups were comparable. Thus, the subjects in the EDG were ingesting a mean (95% CI) of 50% (23.8%, 76.2%) extra energy than that eaten by the SDG. Coefficients of absorption of energy, nitrogen and carbohydrate were similar in the two dietary groups (p = 0.08-0.98). Median (binomial exact 95% CI) fat absorption among subjects receiving the high fat diet (96.3; 92.9, 98.6) was 7% more than in those consuming the low fat diet (89.3; 86.7, 94.1) (p = 0.01). Subjects of the EDG thus, retained almost 50% additional energy as compared to that by SDG.

An experimental study of aerosol penetration through horizontal tubes and Strom-type loops.

Because some designers of aerosol transport systems use the assumption that aerosol penetration through a system is maximized if the flow Reynolds number is 2,800, we have conducted tests to determine if such an assumption is appropriate. Although we do not believe that optimal performance of an aerosol sample transport system can be presented solely in terms of the Reynolds number, we have presented our results in terms of that parameter to compare our work with the results of an earlier study. Two types of experiments were performed. First, the penetration of liquid aerosol particles through horizontal tubes was experimentally investigated for a range of design and operational conditions. For a particle size of 10 microm aerodynamic diameter, the maximum penetration through a 6.7 mm diameter tube was associated with a Reynolds number of approximately 2,000; the maximum penetration through a tube of 15.9 mm occurred at a Reynolds number of about 3,000; and the maximum penetration through a 26.7 mm diameter tube occurred at about 4,000. It was also experimentally demonstrated that for a fixed flow rate through a horizontal tube, there is an optimum tube diameter for which the aerosol penetration is a maximum. An early study dealing with aerosol particle penetration through a 16.8 mm inside diameter loop of tubing (two vertical tubes, two horizontal tubes and three 90 degrees bends) suggested there was a fixed Reynolds number for optimal aerosol penetration independent of particle size. Those experiments were repeated here and the agreement with those tests is excellent; namely, the maximum penetration through a loop of 15.9 mm diameter tube occurs at a Reynolds number of approximately 2,800, independent of particle size. However, when the tube diameter of the transport system layout was changed to 26.7 mm, the Reynolds number associated with maximum penetration varied for different particle sizes, occurring at Reynolds numbers of approximately 5,600 for 8 microm AD particles, 3,800 for 10 microm particles and 3,000 for 15 microm particles.

Hemostatic profile in nephrotic syndrome.

OBJECTIVE: To evaluate the coagulation profile and its relation to steroid therapy, and the frequency of thromboembolic complications and its correlation with coagulation parameters in nephrotic syndrome (NS). SETTING: Hospital based. SUBJECTS AND METHODS: Forty children with NS were subdivided into four groups, namely, fresh cases, steroid dependent, remission after therapy and steroid resistant. An equal number of age and sex matched children served as controls. In all the study and control subjects, detailed clinical examination, liver function tests, renal function tests and detailed coagulation profile were done. Evaluation of renal veins and inferior vena cava for the presence of thrombosis was also done by abdominal ultrasonography. RESULTS: Thrombocytosis was detected in 57.5% and the degree of thrombocytosis was directly related to the amount of proteinuria. The mean prothrombin and thrombin times were within normal range in the study children. The activated partial thromboplastine time (APTT) was prolonged in six cases (15%) and three out of these six children had thromboembolic complications. Antithrombin-III level was significantly lower (p < 0.001) whereas protein C and S were significantly elevated (p < 0.001) as compared to controls. The levels became normal with remission of the disease. Steroid therapy significantly increased the levels of proteins C, protein S. AT-III and fibrinogen as compared to controls. Thromboembolic complications were seen in 3 cases (7.6%) and were associated with very low levels of AT-III and protein C and all three had serum albumin below 2 g/dl. CONCLUSIONS: The importance of coagulation profile in nephrotic syndrome is highlighted and a high index of suspicion for thromboembolic complications is warranted in patients with thrombocytosis, hyper fibrinogenemia, prolonged APTT and in children with low levels of AT-III, protein C and protein S.

Prevalence of hypertension in schoolgoing children.

OBJECTIVE: To establish norms of blood pressure in children of different age groups, prevalence of hypertension and probable precipitating or aggravating factors. DESIGN: Cross sectional study. SETTING: Five thousand school children of Amritsar city. METHODS: Three readings of blood pressure were recorded. Norms for each year age group from 5-17 years of age were established. Persistently hypertensive children were investigated. Influencing factors like family history of hypertension and obesity were taken into account. RESULTS: The blood pressure increased with increase in age with a spurt in systolic blood pressure at the age of 12 years in both the sexes. There was no significant differences in the blood pressure of two sexes at various age groups except for systolic blood pressure at 5,6 and 16 years and for diastolic blood pressure at 9 and 13 years. Only 0.46% children were hypertensive. Children with obesity (n = 342) and family history of hypertension (n = 271) had hypertension in 3.5% (n = 12) and 5.9% (n = 16) cases, respectively as compared to other children in which the prevalence was only 0.23% and 0.14%, respectively. CONCLUSIONS: The norms for determining hypertension in this population were established and it's prevalence was 0.46%. Significant risk factors were obesity and family history of hypertension.

Assessment of thyroid functions and its role in body growth in thalassemia major.

The present study was done to establish the role of thyroid gland in causing growth retardation in regularly transfused thalassemic children. Growth, skeletal maturation and thyroid functions were assessed in 25 patients of thalassemia major in the age range of 5-17 years (mean age 10.3 +/ 3.6 years). Thirteen patients were migrants from Pakistan and 12 were of Indian origin. Twenty-five age and sex matched children who were not anemic served as controls. Thalassemic children received multiple blood transfusions ranging from 36-350 units with a mean of 168.4 +/ 98.9 (+/ 1 SD). The mean pretransfusion hemoglobin was 8.7 +/ 1.6 g/dl. Twenty eight per cent patients were below the 5th percentile for height and another 24% between 5th and 10th percentiles. The height age retardation was more pronounced than bone age retardation. The mean serum total T3 and T4 levels were significantly lower (p < 0.001) and the mean serum TSH levels were significantly higher (p < 0.005) in patients with thalassemia major as compared to the controls. Eight patients had high TSH levels; of these 5 had compensated primary subclinical hypothyroidism (elevated TSH with normal T3 and T4) and 3 had uncompensated primary sub-clinical hypothyroidism (elevated TSH, low T4 and normal T3). Two patients had low T4 with normal T3 and TSH levels. Thyroid dysfunction was not related to age, sex, hemoglobin levels and country of origin but transfused iron load (units/kg, units/year) was significantly higher in patients with hypothyroid function compared to those with euthyroid function (p < 0.005). Height age, weight age and bone age retardations were more pronounced in patients with hypothyroid function; however, the difference was not statistically significant. It is concluded that hypothyroidism is unlikely to be the sole cause of growth retardation; however, it may have a potentiating or permissive role. The strong association of high transfused iron load and decreased thyroid function stresses the need for intensive chelation therapy.

Evaluation of thyroid functions in critically ill infants.

The degree to which thyroid functions are affected by non-thyroid illness and an assessment of its correlation with mortality was evaluated. Thirty infants (20 M, 10 F) with a mean age of 433 +/- 3.28 months (+/- 1 SD), with severe acute systemic illness and 30 healthy controls, age and sex matched, were studied for total serum T3, T4 and TSH levels at admission and recovery or before death. Serum thyroid hormones were measured using standard techniques. There was no significant change in thyroid indices with age, sex, nutritional status, serum protein and C-reactive protein. Serum T3 levels in infants were significantly lower (0.62 +/- 0.63 ng/ml) than the controls (1.90 +/- 0.62) (p < 0.001), with normal T4 and TSH levels at admission. Both serum T3 and T4 levels increased with recovery. Out of 30 infants studied, 14 died whereas 16 were discharged. It was noticed that T3 and T4 values were significantly reduced at or near death when compared with the admission levels (p < 0.001). Prognosis could not be determined at the time of admission, as thyroid indices at admission of patients who died, when compared to infants who were discharged, showed no significant difference in T3, T4 or TSH levels. The above mentioned changes in thyroid indices probably occur as a temporary adaptive mechanism to limit catabolism in states of stress such as infection. Hence, it is suggested that thyroid function tests be interpreted with caution in patients with non-thyroid illness.

Neurosonographic abnormalities in neonates with hypoxic ischemic encephalopathy.

Pattern of neurosonographic (NSG) abnormalities in 150 term newborn infants with hypoxic ischemic encephalopathy (HIE) was studied. Sonographic abnormalities, presumably indicating cerebral edema and or ischemia, were observed in 86% (n = 129) cases. Obliteration of the ventricles occurred as the sole abnormality in 30 (20%) cases. Eighty (53%) patients had diffusely increased echogenicity of the brain parenchyma (DPE) in addition to the compression of the ventricles, sulci and the interhemispheric fissure. Focal parenchymal echodense (FPE) lesions occurred in nine (6%) neonates with HIE. Ten (6.6%) patients, however, had increased periventricular echogenicity (PVE). Two patients, one with focal parenchymal lesions and the other with PVE had obliterated ventricles in addition. Regarding temporal sequence earliest NSG abnormalities were DPE or slit like ventricles that were observed on day-1 itself. Focal or periventricular echogenic lesions, however, made their first appearance on day-3 of life. Twenty one patients had normal scans. Fifty patients with abnormal scans died. None of the infants with normal scans, however, died (p < 0.001). At 4 weeks of age, scans performed in 100 survivors revealed no abnormality in 51 cases. Others showed development of cerebral atrophy (n = 21), multicystic encephalomalacia (n = 2), porencephalic cyst (n = 1), or persistence of PVE without cystic changes (n = 4). The results of this study highlight the diagnostic efficacy of neurosonography in cases of HIE. We suggest that it should be incorporated in the routine evaluation of patients with hypoxic brain injury.

Do insults to the developing lung increase the incidence of wheezing in infants.

This study reports on the possible role of perinatal and early infantile factors in the aetiology of the 'wheezy baby syndrome'. Over a 2 year period we recruited 150 infants from the outpatients department who had a typical wheezing attack, with chest X-ray showing only hyperinflation and non-specific increased markings, and who had been born in hospital with available perinatal and postnatal records. One hundred and fifty control infants were also recruited. A retrospective study was then undertaken comparing the two groups of infants for the incidence of neonatal problems and the incidence of previous lower respiratory tract infections. The results showed that 40 per cent of cases had previously had meconium aspiration syndrome compared with only 2.6 per cent of controls, and that 26.6 per cent of cases had previously had at least one lower respiratory tract infection compared with 5.3 per cent of controls. Other factors, including the incidence of transient tachypnea, and personal and family history of atopy, showed no significant trends. Meconium aspiration syndrome and lower respiratory tract infections are important aetiological factors in the pathogenesis of 'wheezy baby syndrome', rather than inheritance of atopic diathesis.

Anaesthetic technique for elective caesarean section and neurobehavioural status of newborns.

Ninety healthy parturients undergoing elective caesarean section were randomly allocated to receive either general (n = 30), epidural (n = 30) or spinal (n = 30) anaesthesia. Acid-base status, Apgar score and neurobehavioural status, using the neurologic and adaptive capacity scoring (NACS) system, were studied in the newborn. Apgar scores and acid-base parameters were similar in all the three groups. NACS testing revealed significantly more vigorous babies in the spinal anaesthesia group than in the other two groups at 15 min and 2 h interval after delivery, despite a higher incidence of maternal hypotension. We conclude that newborns tend to have a better neurobehavioural status in the early post-delivery period if their mothers receive spinal anaesthesia rather than general or epidural anaesthesia for caesarean section.

Ultrasound evaluation of kidney dimensions in neonates.

This study was done to measure normal renal dimensions of neonatal kidney at various gestational ages sonographically. Knowledge of these measurements may allow earlier diagnosis of a variety of abnormalities. Kidney dimensions (maximum longitudinal length, width, and anteroposterior diameter) were measured within 48 h after birth in 100 healthy neonates with gestational ages from 26.14 to 41.28 weeks and birth weights from 540 to 3250 g using a real time sector scanner with a 7.5 mHz transducer. Renal volume was calculated by volume (V) = L x W x T x 0.5233. Total body surface area (BSA) was determined by BSA = Wt0.425 x Lt0.725 x 71.84. Ponderal index was determined by PI = Wt (g) x 100/(Ht[cm])3. On linear regression analysis, a highly significant correlation was found between renal dimensions and body surface area, gestational age, body weight and length of the baby (p < 0.05). On step wise regression analysis, renal dimensions correlated only with body surface area and the gestational age of the neonate. Regression equations have been provided for rapid computation of renal length, width, and thickness in a given case based on body surface area and the gestational age. Mean (+/- 2 SD) renal volume and renal length were determined based separately on gestational age and body surface area. The data provided can be valuable for evaluating renal abnormalities in preterm neonates.

Ultrasonic evaluation of neonatal subependymal-intraventricular hemorrhage and its complications.

This study demonstrates the value of neurosonography in the evaluation of subependymal-intraventricular hemorrhage (SEH-IVH) and its major complications in the premature infant. Real time sector scans were performed on 150 premature neonates within first 24 hours of life (mean, 10 hrs), and then at 48, 72, and 96 hours and thereafter at weekly intervals. The incidence of SEH-IVH was 22% (n = 33). Twenty seven of the 33 infants had small hemorrhages (Grade I & II), 4 infants sustained Grade III hemorrhage and 2 infants had Grade IV hemorrhage. All hemorrhages occurred in the first 96 hours of life; 50% being diagnosed with the first scan. Larger grades of hemorrhages were generally symptomatic while majority of patients with small hemorrhages had no associated symptoms. The infants especially at risk were those less than 32 weeks' gestation (odds ratio, 29 fold) and/or birth-weight < 1200 gms (odds ratio, 6 fold). Three infants developed post hemorrhagic ventriculomegaly which subsided spontaneously in two of them by the age of 4 weeks. One infant progressed to post hemorrhagic hydrocephalus. The mortality in the study group was 11.3% (n = 17) and correlated to the severity of hemorrhage (39% vs 3.4%; hemorrhagic vs non hemorrhagic group, p < 0.001). At least one screening sonogram is essential within first 4 days of life to diagnose SEH-IVH, which may be otherwise clinically silent. Once the hemorrhage is diagnosed, followup evaluations may be done at weekly intervals to detect post-hemorrhagic ventriculomegaly.