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Biomedical subjects

D Gross

Publications and source records attributed to D Gross.

At least 73 records · Page 4Linked to original sources
PubMed1995

1H-NMR microscopy of tablets.

A 1H-nuclear magnetic resonance (NMR) microscopy method was utilized for the first time to determine the porosity distribution of physically intact tablets. The main advantage of this newly developed method was that porosity cross sections through whole tablets or specific locations could be obtained without mechanically destroying the tested tablet. This was achieved by filling tablet cavities with silicone oil under vacuum. The amount of silicone oil locally within the tablet was then determined by 1H-NMR microscopy, revealing the inverse inner structure. To reduce the measuring time, a paramagnetic gadolinium complex was added to the silicone oil. The cross sectional signals produced by 1H-NMR microscopy through the tablet were transformed into a color image by a specially designed computer graphic program. To improve the signal-noise ratio an algorithm of 3D-filtering was introduced. The maximal spatial resolution achieved with this method was about 95 microns for a cube's edge length corresponding to some 380,000 positions in a 9-mm-diameter compression-coated tablet. Uneven porosity distributions within tablets, cracks, or cavities could be visualized with this newly developed method. Different compaction mechanisms were observed with plastic- or brittle-type tablets. The different states of densification during compaction of powders could be detected. The integrity of compression coatings was determined to be dependent on the pressure load and the location of the core within the coat.

Magnetic Resonance Imaging↗
PubMed1995

The efficacy of parent training for promoting positive parent-toddler relationships.

The effectiveness of a parent training program for promoting positive parent-child relationships was examined among families of 2-year-olds. Forty-six mothers and fathers and their toddlers were assigned to either an intervention or comparison group. Intervention group parents participated in a 10-week program that focused on principles for effectively interacting with their toddlers. Parents completed measures of parenting self-efficacy, depression, stress, and perceptions of their toddler's behaviors and were videotaped playing with their toddlers preintervention, postintervention, and 3 months following the intervention. Repeated measures ANOVAs showed that the parent training program led to significant increases in maternal self-efficacy, decreases in maternal stress, and improvements in the quality of mother-toddler interactions. No significant effects were found among fathers. Explanations for obtaining different outcomes for mothers and fathers are discussed and directions for future research are recommended.

Adult↗
PubMed1995

Insulin secretion in obese and non-obese NIDDM.

Both the insulin response to glucose and the sensitivity to insulin show large variation in the normal population. Many subjects have either a markedly low insulin response or low sensitivity to insulin, with nevertheless normal glucose tolerance. For such subjects to become diabetic, insulin secretion or insulin action must further deteriorate with time, or other factors are added which tip the balance towards diabetes. Most evidence to date indicates that reduced beta-cell responsiveness and reduced insulin sensitivity co-exist in subjects prior to developing NIDDM. Both insulin secretion and insulin action are genetically controlled and influenced by intrauterine and neonatal factors. Insulin secretion and insulin action vary inversely in a closely linked manner; inability to fully compensate for changes in one variable may generate a functional deficit in glucose homeostasis. Subjects combining low functions would run a proportionately larger risk of decompensating the glucose tolerance and be more vulnerable, in terms of diabetes susceptibility, to factors that further reduce insulin output or insulin action. Careful analysis of existing data prompts us to ascribe a dominating role to the impairment of insulin secretion in the pathogenesis of IGT and NIDDM. Patients with NIDDM also exhibit increased proportions of proinsulin and proinsulin conversion intermediates. We used hyperinsulinaemic diabetic and non-diabetic Psammomys obesus to study the possible relationship between steady-state pancreatic insulin stores and the proportion of proinsulin-related peptides in the plasma and the pancreas. A marked increase in these peptides was associated with 90% reduction in insulin stores of the pancreas. After food deprivation, the depletion of pancreatic insulin in the diabetic animals was partially corrected, and the proinsulin/insulin ratio normalized. In contrast, non-diabetic psammomys showed only 50% reduction in pancreatic insulin stores under non-fasting conditions, with no change in proinsulin/insulin ratio. These findings suggest that in the diabetic Psammomys obesus, pancreatic capacity for storage/production of insulin is limited; the metabolic consequences of this limitation are amplified by increased secretory demand secondary to insulin resistance, thus facilitating the establishment of hyperglycaemia, which may in itself further exacerbate the pancreatic dysfunction.

Animals↗
PubMed1995

Temperament in toddlerhood.

The purpose of this article is to describe how toddler temperament can affect parent-child relations using a goodness-of-fit framework. Nursing considerations for assessing toddler temperament with families and providing parental guidance for managing toddlers with difficult temperament styles are discussed. Emphasis is placed on helping parents to understand their toddler's temperament-based behavior and to devise strategies that maximize compatibility between the toddler's temperament and parental expectations.

Child, Preschool↗
PubMed1995

Phenotyping of CYP2C19 with enantiospecific HPLC-quantification of R- and S-mephenytoin and comparison with the intron4/exon5 G-->A-splice site mutation.

S-Mephenytoin 4'-hydroxylase (CYP2C19) is a genetically polymorphic cytochrome P450. A modified method for CYP2C19 phenotyping was evaluated in 174 healthy German volunteers and the results were compared with genotyping for the intron4/exon5 G-->A splice site mutation (m1) of CYP2C19, associated with the poor metabolizer (PM) phenotype. A smaller than usual test-dose of 50 mg (R,S)-mephenytoin was used and urine samples were collected from 0 to 5 h and from 5 to 8 h after administration. Trait measurements included the mephenytoin S/R enantiomeric ratio and the hydroxylation index (i.e. the molar ratio of 4'-hydroxy-mephenytoin urinary recovery to the administered S-mephenytoin dose). S- and R-mephenytoin were quantified by isocratic HPLC with a Chiraspher column and 80% n-hexane and 20% dioxane as the mobile phase. All individuals from whom DNA was available (n = 140, including six phenotypically identified PMs) were analysed for the m1 mutation. The population frequency of this CYP2C19 mutation was 0.15. Four individuals were homozygous for m1 having S/R ratios of 0.9 or greater in both intervals of urine collection. Thus, individuals with an S/R ratio > or = 0.9 were classified as PMs and seven of all 174 phenotyped individuals were PMs (4%; 95% confidence limits: 1.6-8.1%). Heterozygous carriers of m1 (n = 34) had a median S/R ratio (5-8 h urine) of 0.06 compared to 0.01 in individuals without this mutation (n = 102; p = 0.0005, Mann-Whitney U-test). No such gene-dose relation was apparent with the hydroxylation index.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine↗
PubMed1995

Carboxyhemoglobin levels in neonatal immune hemolytic jaundice treated with intravenous gammaglobulin.

In order to examine the effect of intravenous immunoglobulin (IVIG) on the rate of hemolysis in immune hemolytic hyperbilirubinemia, we measured the carboxyhemoglobin levels of 5 newborn infants who were subjected to IVIG treatment. The pretreatment rate of hemolysis, in the 5 patients with isoimmune hemolytic jaundice (3 patients with Rh hemolytic disease of the newborn and 2 patients with ABO hemolytic disease of the newborn), as reflected by carboxyhemoglobin levels was higher than the rate of hemolysis in normal newborn infants. In 4 out of the 5 patients treated with IVIG, there was a rapid decline ( > 30%) of carboxyhemoglobin levels, a pattern which was different from that observed in normal newborn infants with no hemolytic jaundice and in 3 untreated patients with ABO hemolytic disease of the newborn. None of the treated patients required an exchange transfusion. Our preliminary results support the theory that the attenuation of jaundice observed following IVIG treatment in patients with immune hemolytic hyperbilirubinemia is caused, at least in part, by the reduction in hemolysis.

ABO Blood-Group System↗
PubMed1994

A longitudinal model of maternal self-efficacy, depression, and difficult temperament during toddlerhood.

The purpose of this study was to test a model of maternal self-efficacy during toddlerhood using a longitudinal sequential design. Participants were 126 mothers of 1-year olds (Cohort 1) and 126 mothers of 2-year olds (Cohort 2) who completed questionnaires measuring maternal self-efficacy, depression, and perceived difficult toddler temperament three times over 1 year. Data were analyzed using structural equation modeling and maximum likelihood estimation. Findings support a model whereby (a) the more depressed the mother feels, the more likely she is to rate her toddler's temperament as difficult, (b) the more difficult the child's temperament is perceived to be, the lower the mother's estimates of her parenting self-efficacy, (c) the lower the mother's self-efficacy, the greater her depression, and (d) the more depressed the mother feels at one point in time, the more likely she is to remain depressed 6 months later. Implications of the findings are discussed as they relate to self-efficacy theory and nursing intervention with parents of difficult toddlers.

Adult↗
PubMed1994

Lipoprotein levels in newborns and adolescents.

Previous studies established that cardiovascular disease can be predicted early in life. Active modification of risk factors in the general population should include screening as the first step. For this reason, lipoproteins and apolipoproteins were measured in newborns and adolescents. Almost all lipids and apolipoproteins were much lower at birth than at adolescence. Based on these results, reference ranges were calculated.

Adolescent↗
PubMed1994

Parenting confidence during toddlerhood. A comparison of mothers and fathers.

Previous research has shown the Toddler Care Questionnaire (TCQ) to be a valid measure of parenting confidence among mothers of toddlers. However, there is no evidence demonstrating the validity of the TCQ among fathers of toddlers. The purposes of this study were to 1) examine the reliability and validity of the TCQ among fathers of 12- to 36-month old children and 2) compare the childrearing topics mothers and fathers identify as those for which they would like information. Forty-six married mothers and fathers (n = 92) completed the TCQ, three measures of child behavior, and a measure of parental depression. Maternal confidence was related to depression and all measures of child behavior. Paternal confidence was related only to the intensity of the child's behavior. Mothers requested more than twice the amount of childrearing information than did fathers although there were similarities in the types of information requested. The data support the validity of the TCQ and its clinical utility among fathers of toddlers although different factors appear to affect parenting confidence among mothers and fathers.

Adult↗
PubMed1993

Designing interventions in psychosocial research.

There is little guidance in the literature on how to design cost-effective interventions for preventing or treating psychosocial health care problems. Four sources of information are described for developing interventions that are based on a strong theoretical and empirical foundation: (1) an explicit theory for intervention, (2) supporting descriptive data, (3) an evaluation of possible intervention strategies that are consistent with the theory and the supporting data, and (4) focus groups to examine the feasibility and external validity of the intervention before formal testing.

Child Behavior Disorders↗
PubMed1993

Hypertonic saline infusion in hemorrhagic shock treated by military antishock trousers (MAST) in awake sheep.

OBJECTIVES: To determine the effect of military antishock trousers (MAST) combined with hypertonic saline in controlled hemorrhagic shock in an awake sheep model. DESIGN: Prospective, randomized, controlled study. SETTING: University research laboratory. SUBJECTS: Healthy adult sheep (21 to 33.5 kg) were studied in four experimental groups. INTERVENTIONS: Sheep underwent cannulation of the jugular vein and the carotid artery. An indwelling catheter was also inserted into their bladders. Mean arterial, pulmonary arterial, pulmonary artery occlusion, and central venous pressures, cardiac and stroke volume indices, systemic and pulmonary vascular resistances, PaO2 and PaCO2, and serum lactate and hemoglobin concentrations were measured at baseline, after induction of hemorrhagic shock, and subsequently during resuscitative treatments of normal saline, MAST, hypertonic saline, and the combination of MAST and hypertonic saline. MEASUREMENTS: Controlled hemorrhagic shock was induced by arterial bleeding of 40 mL/kg in all animals. The sheep were randomized into four groups. In group 1 (n = 5), controlled hemorrhagic shock was treated by 5 mL/kg sodium chloride 0.9% (isotonic saline). In group 2 (n = 6), controlled hemorrhagic shock was treated by 5 mL/kg sodium chloride 7.5% (hypertonic saline). In group 3 (n = 5), controlled hemorrhagic shock was treated by MAST inflated to 40 mm Hg followed by 5 mL/kg sodium chloride 0.9%. In group 4, controlled hemorrhagic shock was treated by MAST (40 mm Hg) followed by 5 mL/kg of hypertonic saline. MAIN RESULTS: Arterial bleeding was followed by significant decreases in mean arterial pressure (87 +/- 1 to 41 +/- 4 mm Hg; p < .001), cardiac index (4.6 +/- 0.4 to 2.0 +/- 0.2 L/min/m2; p < .001), and urine output (102 +/- 30 to 13.0 +/- 7 mL/hr; p < .001), and an increase in systemic vascular resistance (1517 +/- 130 to 2601 +/- 370 dyne.sec/cm5; p < .001). MAST inflation in group 3 increased systemic vascular resistance to 3018 +/- 399 dyne.sec/cm5 (p < .05) and mean arterial pressure to 79 +/- 5 mm Hg (p < .05), while cardiac index, urine output, and lactate concentration remained unchanged. Infusion of hypertonic saline after MAST inflation (group 4) resulted in an increase in mean arterial pressure to 99 +/- 4 mm Hg (p < .001), an increase in cardiac index to 4.1 +/- 0.4 L/min/m2 (p < .001), an increase in urine output to 221 +/- 93 mL/hr (p < .001), and a decrease in systemic vascular resistance to 1847 +/- 175 dyne.sec/cm5 (p < .005). CONCLUSIONS: In hemorrhagic shock, the combination of MAST and hypertonic saline increases mean arterial pressure, improves cardiac output and tissue perfusion during the application of MAST, and also prolongs for > 2 hrs the short beneficial effect of hypertonic saline on mean arterial pressure.

Animals↗
PubMed1993

The effect of ventilatory muscle training on respiratory function and capacity in ambulatory and bed-ridden patients with neuromuscular disease.

Most patients with neuromuscular disease develop muscle weakness, including the ventilatory muscles leading to respiratory difficulty and, at times, respiratory insufficiency. We studied the effect of ventilatory muscle training on the ventilatory function and capacity of patients with various types of neuromuscular disease. The ambulatory patients were divided into three major groups. Group I (n = 6) patients with motor neuron disease (MND), such as amyotrophic latera sclerosis; Group II (n = 11) patients with myoneural junction disease (MNJ), such as myasthenia gravis and: Group III (n = 7) patients with muscle diseases such as progressive muscular disease. Patients were evaluated for their neuromuscular diagnosis and status of the disease. A complete physical examination and the various neuromuscular tests were performed. A complete respiratory evaluation was applied: pulmonary function tests (PFT), maximum inspiratory pressure (MIP). Patients then started ventilatory muscle training by resistive breathing, as a prophylactic treatment, for 10 min, three times daily, with a resistance which would induce fatigue. All tests were repeated every six weeks, and the results were as follow: forced vital capacity (FVC) changed from 38.8 +/- 12.3 to 53.2 +/- 9.6% (NS) of predicted value in group I, from 49.8 +/- 8.7 to 66.1 +/- 7.5% (p < 0.002) in group II, and from 47.0 +/- 7.5 to 53.3 +/- 7.6% (p < 0.04) in group III. Forced expiratory volume in one second (FEV1) was 34.8 +/- 11.0, 46.3 +/- 5, and 45.1 +/- 9% for the three groups, respectively, and did not change with training.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Magnetic resonance microscopy--new prospects for endodontics].

With the use of magnetic resonance microscopy (MRM) the options and limitations of this modern technique in reproducing teeth and endodontium should be evaluated. Therefore, extracted teeth were stored in formaline and measured in two different devices of the magnetic resonance technique. One is common for material research and normally used for spectroscopy of solids. Measuring takes place in the strayfield of the magnet which leads to the term "Stray Field Imaging" (STRAFI). The other one is a spectroscopy with an additional micro-imaging device (magnetic resonance microscope) where resolutions up to (100 microns)3 can be reached. For the first time the STRAFI allowed to make pictures from the hydrogen-protons of the teeth's hard substances. A two or three dimensional imaging on the basis of microscopic resolution became reality. In addition the MRM allowed to depict the soft tissue portion and the outer contour of the teeth in 2D and 3D. The two-dimensional pictures were able to show a texture within the pulp tissue. The three-dimensional images enabled a naturalistic and non-destructive visualization of the outer surface and the pulp room. The results shown here open very new perspectives for endodontics.

Dental Pulp Cavity↗
PubMed1993

The effect of heat load and dehydration on hypertonic saline solution treatment of controlled hemorrhagic shock.

Small volume hypertonic saline solution has been suggested for initial effective resuscitation of hemorrhagic shock. The effect of hypertonic saline solution in controlled hemorrhagic shock was studied in rats subjected to dehydration or heat, or both. The rats were randomly divided into four groups--group 1 (n = 19), normal rats; group 2 (n = 21), water deprivation for 12 hours; group 3 (n = 20), heating at 37 degrees C. for five hours, and group 4 (n = 19), water deprivation for 12 hours and heating at 37 degrees C. for five hours. Controlled hemorrhagic shock was induced in all rats by arterial bleeding of 15 milliliters per kilogram and the rats were divided into three treatment subgroups--group a was untreated, group b was treated with 5 milliliters per kilogram 0.9 percent NaCl and group c was treated with 5 milliliters per kilogram 7.5 percent NaCl. Arterial bleeding of 15 milliliters per kilogram in group 1 resulted in decrease in mean arterial pressure (MAP) to 44 +/- 2 millimeters of mercury (p < 0.001) and pulse rate to 280 +/- 13 per minute (p < 0.01). A similar decrease in MAP and pulse rate was observed in all four groups. Infusion of hypertonic solution (HTS) in group 1c was followed by an increase in MAP to 89.0 +/- 9.7 milliliters of mercury (p < 0.01) in 15 minutes. This was significantly higher than infusion of normal saline solution in group 1b (p < 0.01) or untreated group 1a (p < 0.01). This difference remained significant also after 45 minutes from infusion (p < 0.05 and p < 0.05, respectively). The increase in MAP in response to HTS in group 1c after 15 minutes was significantly higher than the rise in groups 2c (p < 0.05), 3c (p < 0.05) and 4c (p < 0.05). This difference in response to HTS remained significant 45 minutes from infusion in groups 3c (p < 0.05) and 4c (p < 0.05), but not in dehydrated rats in group 2c. Arterial bleeding did not alter serum sodium significantly in all four groups. Infusion of HTS in group 1c was followed by an increase in serum sodium from 149.1 +/- 1.4 to 161.1 +/- 2.4 milliequivalent per liter (p < 0.001), while infusion of HTS in group 4c, where serum sodium was initially elevated to 157.1 +/- 3.0 milliequivalent per liter, did not further elevate the serum sodium level.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗