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Biomedical subjects

N R Mehta

Publications and source records attributed to N R Mehta.

At least 37 records · Page 2Linked to original sources
PubMed1991

Strength and bite, Part 1: An analytical review.

The original clinical observations and research in the area of bite and strength enhancement studied individuals with obvious malocclusion and a subject population with mixed occlusions. An increase in isometric strength was obtained when biting on a K-MORA, an intraoral device that supports a mandibular position determined by a functional criterion. The criterion is a locking response to the Isometric Deltoid Press, a muscle challenge used by kinesiologists. Rather than replication with improved design, subsequent research (1) employed different mandibular positions based on therapeutic, electrical impulse or structural criteria; (2) tested mainly isokinetic strength; (3) referred to "strength" without qualification, implying more generalization than the findings actually allowed; (4) criticized and rejected positive findings by attributing strength increase to the placebo effect even though in no instance has the placebo effect been demonstrated in this field. Considering published and unpublished research on isometric strength and the irrelevance of many studies that found no difference in isokinetic strength, it is concluded that it is most probable that isometric strength is increased by the K-MORA in mixed populations.

Bite Force↗
PubMed1991

Adherence of medium-chain fatty acids to feeding tubes of premature infants fed formula fortified with medium-chain triglyceride.

Adherence of medium-chain triglyceride (MCT) oil to feeding tubes during gavage feeding of Enfamil formula was quantitated. Infants were fed similar volumes of either unfortified formula (n = 11) or MCT oil-fortified formula (0.5 ml/oz); either the MCT oil was mixed with the formula before feeding (n = 11) or the MCT oil was delivered into the feeding tube and then was followed by formula (n = 11). The fat residue in the feeding sets was quantitated by gravimetry, and individual fatty acids were characterized by gas-liquid chromatography. The data show that only trace amounts of lipid (0.23 +/- 0.04%) adhered to feeding sets during feeding of unfortified formula. Significantly more lipid (p less than 0.0005) adhered when formula was fortified with MCT oil, and the method of feeding greatly affected lipid adherence, i.e., 1.52 +/- 0.21% when the MCT oil was followed by formula versus 10.20 +/- 1.76% when the MCT oil was mixed with formula before feeding. Analysis of the fat residue of fortified formula showed that greater than 90% was composed of C8:0 and C10:0, the major fatty acid components of MCT oil. We suggest that care be exercised when fortifying infant formula with MCT oil.

Adhesiveness↗
PubMed1991

Fat absorption in premature infants: medium-chain triglycerides and long-chain triglycerides are absorbed from formula at similar rates.

Fat absorption from two different premature infant formulas and one full-term formula containing three different fat blends was investigated in two groups of premature infants. The first group of nine infants (gestational age, 29.1 +/- 0.88 weeks; postnatal age, 3.13 +/- 0.71 weeks) was fed alternately for 1 week each SMA preterm formula containing either high levels (50%) of medium-chain triglycerides (MCT) (6:0, 8:0, and 10:0) or high levels (86%) of long-chain triglycerides (LCT) (greater than or equal to C12). Except for fat blends, the formulas were otherwise identical. The second group of 11 infants (gestational age, 30.5 +/- 0.77 weeks, studied at a postnatal age of 4.33 +/- 0.91 weeks) was fed for 1 week a full-term infant formula, S-26, containing 98% LCT. Fat absorption (studied during a 3-day fat balance period) was similar irrespective of fat blend: 89.08 +/- 2.37% during feeding of preterm SMA, 50% MCT; 87.0 +/- 3.81% during feeding of preterm SMA, 86% LCT; and 83.00 +/- 2.89% during feeding of S-26, 98% LCT. Weight gain (grams per day) and increase in length (centimeters per day) were 23.2 +/- 1.7, 21.20 +/- 1.7, and 14.28 +/- 2.9, and 0.17 +/- 0.06, 0.16 +/- 0.04, and 0.22 +/- 0.07 during feeding of the three fat blends, respectively. Lipase activity levels in fasting gastric aspirates were higher during feeding of the LCT than the MCT formula. The possible stimulation of gastric lipase secretion secondary to long-chain fatty acid stimulation of cholecystokinin secretion might be related to the efficient digestion of formula fat, irrespective of triglyceride-fatty acid chain length.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary Fats↗
PubMed1990

The impact of gestational length on human milk selenium concentration and glutathione peroxidase activity.

Longitudinal changes in selenium (Se) and protein concentrations and glutathione peroxidase (GSH-Px) activity of milk collected from healthy mothers of term (n = 12), preterm (n = 10), and very preterm (n = 12) infants were assessed. All infants were size appropriate for gestational age. Milk samples representative of colostrum (d 3), transitional (d 7), and mature milk (d 21 and 42) were assayed. The content of Se in the colostrum secreted by mothers of preterm infants was significantly greater than the Se content of milk secreted by the same mothers at d 21 and 42 of lactation. Mothers of term and very preterm infants, however, produced colostrum with significantly higher levels of Se than milk produced at d 7 (p less than 0.05), d 21 (p less than 0.01), or d 42 (p less than 0.001). Significant differences between the protein concentrations measured in early lactation and in late lactation were evident in all maternal groups. Protein content did not differ significantly among groups at anytime during lactation. An age-related difference was detected in milk GSH-Px activities of mature milk (d 21). Mature milk produced by mothers of very preterm infants on d 21 of lactation contained significantly greater enzyme activity (p less than 0.05) than milk produced by mothers of term infants at the same stage of lactation. Activity of GSH-Px in milk from mothers of very preterm and preterm infants paralleled previously noted changes in long-chain polyunsaturated fatty acid content in human milk with the progression of lactation.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1989

Lipases in human milk: effect of gestational age and length of lactation on enzyme activity.

Human milk contains two lipases, bile salt-stimulated lipase (BSSL) and lipoprotein lipase (LPL). In the mammary gland, LPL provides long-chain fatty acid for milk fat synthesis. LPL has no known function in milk, but has been implicated in milk fat hydrolysis during cold storage. BSSL may have an important role in infant fat digestion. The aims of the present studies were to assess (1) the methodological validity of using whole milk to analyze BSSL activity, (2) the longitudinal variation of BSSL and LPL activity in the milk of mothers delivering premature and full-term infants, and (3) the stability of BSSL and LPL activity during cold storage. Diluted whole milk and purified BSSL were shown to have similar characteristics. LPL activity was equally stable at -20 and -70 degrees C, whereas BSSL activity was higher in milks stored at -70 than at -20 degrees C (38.8 +/- 0.88 vs 33.3 +/- 0.87 U/ml milk, respectively; 1U = 1 mumol free fatty acid release/min). Levels of BSSL activity in preterm and term milk were similar. LPL activity tended to be higher in term milk. Overall, BSSL activity showed significant longitudinal variation, being highest at 1 and 3 weeks of lactation (43.2 +/- 0.04 and 42.6 +/- 1.03 U/ml milk, respectively). For LPL, the longitudinal pattern of activity depended upon the length of pregnancy. Implications for infant nutrition and mammary gland biology are discussed.

Female↗
PubMed1989

Gastric lipolysis and fat absorption in preterm infants: effect of medium-chain triglyceride or long-chain triglyceride-containing formulas.

The extent of gastric lipolysis, fat absorption, and infant weight gain was studied in 12 preterm infants (gestational age 28.75 +/- 0.50 weeks, postnatal age 6.08 +/- 0.81 weeks) fed medium-chain triglyceride or long-chain triglyceride formula for 1 week in a crossover design. The former formula contained 42% of 8:0 and 10:0 and 19% of 12:0, 14:0, and 16:0; the latter formula contained only 7% of 8:0 and 10:0 and 46% of 12:0, 14:0, and 16:0. Gastric aspirates were obtained on the second and third day of formula feeding for quantitation of lipase activity and of the extent of gastric lipolysis. Fat balance studies were conducted during the last three days of each feeding regimen. The study showed that (1) there was marked hydrolysis of formula fat in the stomach during feeding of either medium-chain triglyceride formula or long-chain triglyceride formula (20% and 16%, respectively); (2) lipase activity in the gastric aspirates was less during feeding of medium-chain triglyceride formula than before the meal, which suggested stimulation of lipase secretion by long-chain fatty acid released from long-chain triglyceride formula fat or more rapid binding of lipase to ingested lipid in the medium-chain triglyceride formula; (3) fatty acid distribution in glycerides and free fatty acids showed preferential release of medium-chain (8:0, 10:0) and long-chain unsaturated (18:1, 18:2) fatty acids in the stomach. The low content of 8:0 and 10:0 in gastric triglyceride and free fatty acids suggested that medium-chain fatty acids were absorbed directly in the stomach.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗
PubMed1989

Meningococcal meningitis in an industrial area adjoining Surat City--some clinico-epidemiological aspects.

An industrial area with poor sanitation and inhabited by migrant, male predominant population, situated South to Surat City, experienced an outbreak of pyogenic meningitis during 1985-87. A total of 197 cases of meningitis with 34 deaths were reported during a period of 1 1/2 years. Neisseria meningitidis was the predominant pathogen isolated from 66 out of 138 CSF samples. Recently migrated males of productive age groups drawn from the States of Uttar Pradesh and Orissa were predominantly affected. Male to female ratio was found to be 7.2:1. Nearly 2/3rd of the cases were reported during the dry colder months of winter and spring. Pregnancy and childbirth appeared to be important predisposing factors in females. Nine cases were reported from the family contacts of cases. Majority of the cases were labourers doing manual work.

Disease Outbreaks↗
PubMed1988

Effect of total parenteral nutrition on lipase activity in the stomach of very low birth weight infants.

Lipase activity was quantitated in gastric aspirates of 7 premature infants (gestational age 24-29 weeks) during periods of total parenteral nutrition (TPN), mixed parenteral nutrition and gavage feeding or exclusive gavage feeding. The infants were studied from birth until the establishment of exclusive gastric gavage feeding. Lipase activity in gastric aspirates (quantitated by the hydrolysis of 3H-triolein at pH 4.2 and expressed in nmol 3H-oleic acid released/min/ml gastric aspirate) did not differ significantly as a function of mode of feeding: 570 +/- 235 during TPN, 260 +/- 145 during mixed parenteral nutrition and gavage feeding, and 374 +/- 149 during exclusive gastric gavage feeding. The data suggest that, contrary to the intestine and pancreas, the digestive function of the stomach is not impaired during TPN in the very preterm infant.

Humans↗
PubMed1986

Lack of effect of citric acid treatment of root surfaces on the formation of new connective tissue attachment.

Previous reports have described an accelerated induction of new attachment and repair of furcations in dogs after treatment of roots surfaces with citric acid, but few controlled clinical studies have examined its usefulness in surgical treatments for periodontitis. This study compared the effects of a comprehensive surgical plaque control procedure with or without citric acid treatment for generalized and localized effects on gingival height, probing pocket depth and attachment level in 72 teeth in 3 patients who were treated surgically for moderate periodontitis and examined every 3 months for 1 year. No statistically significant differences in the effects of the 2 treatments were observed. These observations suggest that there is no clinical advantage of citric acid conditioning of the root surface during surgical treatment of periodontitis.

Adult↗
PubMed1985

Lipids in milk and the first steps in their digestion.

Human milk contains 3.0% to 4.5% fat. The fat is contained within membrane-enclosed milk fat globules. The core of the globules consists of triglycerides (98% to 99% of total milk fat) whereas the globule membrane (which originates from the mammary secretory cell's Golgi and cell membranes) is composed mainly of phospholipids, cholesterol, and proteins. Milk fat content and composition change during lactation. Whereas the triglyceride level rises, the phospholipid and cholesterol concentrations decrease during the transition from colostrum to mature milk, resulting in an increase in the size of the milk fat globules. Digestion of milk fat depends on the consecutive action of several lipases. The first step is the partial hydrolysis of the milk fat globule core by lingual and gastric lipases in the stomach. Hydrolysis continues in the duodenum, where the bile salt-stimulated lipase of human milk and pancreatic lipase complete the process initiated in the stomach.

Animals↗
PubMed1984

Comparison of the phospholipid composition of breast milk from mothers of term and preterm infants during lactation.

Phospholipids were determined in milk on postpartum day 3 (colostrum) and days 7, 21, 42, and 84 from mothers of 18 very premature (26 to 30 wk gestation age), 28 premature (31 to 36 wk), and 6 term (37 to 40 wk) infants. Lipids were analyzed by thin-layer and gas-liquid chromatography. Total fat content increased during lactation whereas phospholipids and cholesterol declined. Phospholipids were separated from neutral lipids by column chromatography and distributed by preparative thin-layer chromatography into classes, sphingomyelin, phosphatidyl choline, serine, inositol, and ethanolamine for fatty acid analysis. Phospholipids exhibited a remarkable constancy in class percentages in milks from mothers giving birth prematurely or at term. Changes were observed in fatty acid composition within each of the phospholipid classes as secretion progressed from colostrum (3d) to transitional (7d) to mature milk (21, 42, 84d). These changes in phospholipid fatty acid composition occurred only during the first 3 wk of lactation. Mature milk was found to be relatively constant in phospholipid composition.

Colostrum↗