The axostyle of Saccinobaculus. I. Structure of the organism and its microtubule bundle.

The axostyle of the flagellate Saccinobaculus is a motile ribbon composed of microtubules, cross-bridged to form interconnected rows. We find a centriole-related row of dark-staining tubules near the nucleus at the anterior end of the axostyle. Other tubule rows bind parallel to this primary row, acquire ordered relationships, and become the tubules of the axostyle proper. The number of tubule rows is constant in Saccinobaculus lata from the region near the nucleus to within a few micrometers of the posterior tip of the cell. In Saccinobaculus ambloaxostylus a few tubule rows are added to the axostyle posterior to the nucleus, giving this axostyle a leaf spring construction. The tubules of S. lata are held in rows by links with a 140 A periodicity along the tubule axis; bridges between rows of tubules are also seen but are not apparently periodic. Each tubule in S. ambloaxostylus shows an axial periodicity of 150 A due to pairs of arms, one of which is always part of the intrarow link. Interrow bridges in this species run either from tubule to tubule or from tubule to the free arm, but as in S. lata they do not display an obvious axial periodicity. An average unit cell is presented for the axostyle of each species, and the relation of the intertubule links to the microtubule substructure is discussed.

Gestational diabetes mellitus. Heterogeneity of maternal age, weight, insulin secretion, HLA antigens, and islet cell antibodies and the impact of maternal metabolism on pancreatic B-cell and somatic development in the offspring.

We have examined gravida with gestational diabetes mellitus (GDM), as defined by the National Diabetes Data Group (Diabetes 1979; 28:1039), for phenotypic and genotypic heterogeneity. Fasting plasma glucose (FPG) at diagnosis was used for further stratification of GDM according to putative metabolic severity into class A1 (FPG less than 105 mg/dl [N = 129]), class A2 (FPG 105-129 mg/dl [N = 47]), and class B1 (FPG greater than or equal to 130 mg/dl [N = 23]). All GDM classes tended to be older and heavier than consecutive gravida with documented normal glucose tolerance (controls, N = 148). Subdivision into "lean" and "obese" indicated that plasma immunoreactive insulin (IRI) was greater after overnight fast in the obese of all groups except B1. However, absolute increases in IRI above fasting levels in response to glucose during OGTT were significantly enhanced by obesity only in class A2 gravida. Adjustment for the effects of age and weight by covariate analysis indicated that the IRI response to glycemic stimulation is usually attenuated in all forms of GDM. Mean values for increases in IRI above fasting values during the first 15 min and IRI increments relative to the increases in plasma glucose throughout the 180-min OGTT were below control values in all GDM groups and progressively so, i.e., A1 less than A2 less than B1. The absolute insulinopenia was not invariable; a small number of gravida from all GDM groups displayed well-preserved IRI responses to oral glucose. Genotypic evaluation of the GDM population disclosed an increased occurrence of "markers" known to be associated with type I diabetes mellitus.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term prospective evaluation of offspring of diabetic mothers.

We have suggested that altered maternal metabolism may affect the subsequent anthropometric and neuropsychological development of children who were in utero during disturbances in maternal fuel economy. This study reports the physical growth through 8 yr of age and the neuropsychological development through 4 yr of age in offspring of diabetic mothers (ODM). At birth, 50% of infants had weights greater than 90th percentile for gestational age. By 12 mo, length and weight were similar to the general population. Height remained normal until 7 yr of age, when it became slightly greater than average. After 5 yr of age, relative weight increased dramatically, and by 8 yr of age, half of the ODM had weights greater than 90th percentile. This childhood obesity in ODM is correlated with maternal prepregnant weight and independently with amniotic fluid insulin at 32-38 wk gestation. The Brazelton Neonatal Behavioral Assessment Scale (BNBAS) was administered to 185 newborn ODM. Significant correlations were found between poorer second- and third-trimester glycemic regulation and lower scores in three of four newborn BNBAS dimensions. The Stanford-Binet Intelligence Scale was measured in 102 ODM at 4 yr of age. We found an inverse correlation between childhood IQ and second- and third-trimester maternal lipid metabolism (serum free fatty acids and beta-hydroxybutyrate). This correlation is not explained by adverse perinatal events, socioeconomic status, maternal IQ, ethnicity, or diabetes type. These long-range associations between altered maternal metabolism and childhood growth and development continue to support Freinkel's hypothesis of fuel-mediated teratogenesis.

Financial implications of implementing standards of care for diabetes and pregnancy.

This article examines the financial implications of implementing standards of care for pregnancy among women with diabetes, including both the costs of enhanced treatment and the savings of avoided adverse outcomes. Numerous studies have demonstrated the harmful effects of poor blood glucose control for both mother and fetus. Standards set forth by the American Diabetes Association aim to reduce maternal complications and fetal adverse outcomes, such as congenital malformations. Because the precise configuration of resources required to meet these standards was not outlined in the American Diabetes Association statement, a panel of physicians (all specialists in pregnancy care for women with diabetes) was convened to develop a model program. Implementing such a program during the preconception and prenatal periods will represent an intensification of resource use in the outpatient setting. However, through these preventive measures, medical care costs for maternal and fetal complications can be avoided.

Cost-benefit analysis of preconception care for women with established diabetes mellitus.

OBJECTIVE: To determine whether the additional costs of preconception care are balanced by the savings from averted complications. Several studies have demonstrated the efficacy of preconception care in reducing congenital anomalies in infants born of mothers with pre-existing diabetes mellitus. RESEARCH DESIGN AND METHODS: This study used literature review, consensus development among an expert panel of physicians, and surveys of medical care personnel to obtain information about the costs and consequences of preconception plus prenatal care compared with prenatal care only for women with established diabetes. Preconception care involves close interaction between the patient and an interdisciplinary health-care team as well as intensified evaluation, follow-up, testing, and monitoring. The outcome measures assessed in this study are the medical costs of preconception care versus prenatal care only and the benefit-cost ratio. RESULTS: The costs of preconception plus prenatal care are $17,519/delivery, whereas the costs of prenatal care only are $13,843/delivery. Taking into account maternal and neonatal adverse outcomes, the net savings of preconception care are $1720/enrollee over prenatal care only and the benefit-cost ratio is 1.86. The preconception care program remained cost saving across a wide range of assumptions regarding incidence of adverse outcomes and program cost components. CONCLUSIONS: Despite significantly higher per delivery costs for participants in a hypothetical preconception care program, intensive medical care before conception resulted in cost savings compared with prenatal care only. Third-party payers can expect to realize cost savings by reimbursing preconception care in this high-risk population.

The effects of severe maternal diabetes on glucose transport in the fetal rat.

We mimicked the condition of severe maternal diabetes by administering high doses of streptozotocin (STZ) to the pregnant rat to determine the effects of increased glucose availability on fetal glucose transport and to assess whether a relationship might exist between glucose transport and altered fetal growth. Fetuses of STZ-treated pregnant rats were growth retarded (3.86 +/- 0.13 vs. 5.29 +/- 0.06 g), hyperglycemic (30.0 +/- 1.0 vs. 5.5 +/- 0.5 mM/liter), and hyperinsulinemic (1263.8 +/- 138.3 vs. 817.9 +/- 116.7 pM/liter). Glucose uptake, Glut 1 messenger RNA (mRNA), and Glut 1 protein were greater in STZ-treated fetal brain than in controls (50%, 83%, and 50%, respectively; P < 0.05). Glut 3 mRNA levels in STZ-treated and control fetal brain were equivalent and significantly less than levels of Glut 1. Glucose uptake in muscle of STZ fetuses was 70% greater than control values (P < 0.05). Glut 1 mRNA levels were increased by 93% in STZ fetal muscle (P < 0.05). Neither Glut 3 nor Glut 4 mRNA could be detected in STZ-treated and control fetal muscle. Glut 1 protein levels were increased by 70% in STZ-treated fetal muscle compared to control muscle (P < 0.05). These observations indicate that altered glucose transport per se does not directly contribute to fetal growth retardation with maternal STZ diabetes. Perturbations in other physiological and metabolic factors may contribute to the pathogenesis of fetal growth retardation in STZ-induced diabetes during pregnancy.

The effect of insulin and insulin-like growth factor-I on glucose transport in normal and small for gestational age fetal rats.

In a model of asymmetric small for gestational age (SGA) fetal growth retardation, we have previously found that glucose transport is decreased in lung (an organ whose growth is restricted) and unaffected in brain (growth is normal). The SGA model alters a number of physiological and metabolic factors that may decrease glucose transport, thereby causing growth retardation. Specifically, insulin and insulin-like growth factor-I (IGF-I) concentrations are diminished in SGA fetuses. We hypothesized that the specific modulation by these factors of gene expression of a glucose transporter, Glut-1, is impaired. We performed bilateral uterine arterial ligation in pregnant rats on day 19 of gestation (term = 21.5 days) and obtained fetal brain, lung, and skeletal muscle on day 20. Lung and muscle explants and monolayers of glial cells and type II pneumocytes were cultured in the presence or absence of insulin or IGF-I for 24 h. Glucose uptake and levels of Glut-1 protein and mRNA were similar in brains of SGA and control fetuses and were not affected by treatment with insulin or IGF-I. Treatment with insulin or IGF-I increased glucose uptake and levels of Glut-1 protein and mRNA in a dose-dependent manner in lung and muscle from control fetuses. However, the response in SGA lung was not as great as that in controls. SGA muscle demonstrated no significant response to either hormone. These findings suggest that changes in glucose transport modulation might contribute to the development of asymmetric growth retardation, and that maintenance of normal transporter function and expression in brain may play a role in sparing its growth.

Glucose regulates glut 1 function and expression in fetal rat lung and muscle in vitro.

The mechanisms that regulate cellular glucose transport (glucose uptake, Glut 1 protein, and mRNA) in the fetus are not known. We attempted to define the effects of glucose availability alone in vitro on glucose transport in fetal rat lung and muscle. On day 20 of gestation (term = 21.5 days), lung and muscle tissues were harvested from normal fetal rats, minced into explants, and cultured for 24 h in standard culture medium (lung, 28 mM; muscle, 5.5 mM glucose). Explant cultures were washed and cultured for an additional 1 or 24 h in medium containing one of four concentrations of glucose: 1) glucose free, 2) low glucose, 3) high glucose, and 4) standard. Twenty-four-hour, but not 1-h, treatment of fetal lung and muscle in vitro with low concentrations of glucose increased 2-deoxyglucose uptake and Glut 1 protein and mRNA levels (P < 0.05). Culture in high glucose medium for 24 h, but not 1 h, decreased 2-deoxyglucose uptake and Glut 1 protein and mRNA levels (P < 0.05). Culture in glucose-free medium for 24 h up-regulated glucose transport in lung and down-regulated glucose transport in muscle, indicating that regulation of fetal glucose transport may be tissue specific. These findings differ from our studies of in vivo models of altered fetal growth and abnormal glucose availability. Maternal bilateral uterine artery ligation limits glucose availability to the fetus, and glucose transport is down-regulated. Low glucose in vitro has the opposite effect. Maternal diabetes increases glucose availability to the fetus, and glucose transport is up-regulated. High glucose in vitro does the opposite. We conclude that while glucose alone in vitro affects its uptake by the cell, other factors that are altered in these in vivo conditions act in concert with glucose to regulate glucose transport in the fetus.

Circulating levels of insulin, insulin-like growth factor-I (IGF-I), IGF-II, and IGF-binding proteins in the small for gestational age fetal rat.

Insulin-like growth factors (IGFs) are important regulators of somatic growth in childhood and circulate in association with specific binding proteins (IGFBPs). Insulin is important for the regulation of IGFs and IGFBPs in postnatal life and is required for normal growth in utero. We asked whether alterations in the availability of IGFs and/or their BPs may contribute to impaired fetal growth 24 h after bilateral uterine artery ligation when circulating levels of insulin are low and fetuses are small for gestational age (SGA). Bilateral uterine arterial ligation or sham surgery was performed on maternal rats on day 19 of gestation (term = 21.5 days). One day after ligation, fetuses were SGA compared to shams (2.9 +/- 0.1 vs. 3.5 +/- 0.1 g/fetus, respectively; P < 0.001), and liver weight was reduced (242 +/- 9 vs. 300 +/- 6 mg/liver; P < 0.001). Serum levels of both insulin and IGF-I were reduced approximately 50% in SGA litters compared to those in shams (P < 0.001) and correlated with each other (P < 0.02). IGF-I levels also correlated with fetal body and liver weights (P < 0.005 for each) even after controlling for the effects of insulin. Insulin levels correlated with body and liver weights (P < 0.02 and P < 0.03, respectively), but these relationships were not significant after controlling for the effects of IGF-I. Serum levels of IGF-II were not significantly reduced in SGA and did not correlate with fetal weight or insulin or IGF-I levels. [125I]IGF-I binding assay demonstrated that the availability of IGFBPs was increased in SGA serum, and Western ligand blotting indicated that circulating levels of 32K IGFBPs were increased in SGA fetuses compared to shams. Densitometric analysis indicated that levels of 32K IGFBPs were 4-fold greater in SGA litters (P < 0.001 vs. shams), and the level of 32K IGFBPs correlated with fetal body and liver weights (P < 0.05 for each) and with levels of both insulin and IGF-I (P < 0.001 for each), but not with levels of IGF-II. Immunoblotting with newly developed antiserum against rat IGFBP-1 confirmed that levels of immunoreactive 32K IGFBP-1 are increased in SGA serum, and immunoprecipitation studies confirmed that IGFBP-1 accounted for the rise in 32K IGFBPs in SGA serum.(ABSTRACT TRUNCATED AT 400 WORDS)

Circulating levels of insulin-like growth factor binding protein-1 (IGFBP-1) and hepatic mRNA are increased in the small for gestational age (SGA) fetal rat.

Insulin-like growth factors (IGFs) circulate in association with a family of specific binding proteins (BPs). Recently, we reported that circulating levels of IGFBP-1 and IGFBP-2 are increased in streptozotocin-diabetic adult rats and are differentially regulated in accordance with insulin and metabolic status. Since IGF BPs appear to be important modulators of IGF bioactivity in post-natal life, we asked whether serum levels of IGF BPs also might be altered in utero when the delivery of maternal nutrients is restricted and fetal growth is impaired. Bilateral uterine artery ligation or sham surgery was performed on maternal rats on d 19 of gestation (term 21.5 d). One day after ligation (d 20), fetuses were (SGA) compared to shams (3.1 +/- 1 vs 3.7 +/- 0.2 g, p less than .02) and serum levels of glucose (70 +/- 5 vs 96 +/- 6 mg/dL, p less than .01) and insulin (62 +/- 4 vs 138 +/- 14 microU/mL) also were reduced. In contrast, serum [125I]IGF-I binding activity was markedly increased in SGA litters compared to sham (65 +/- 5% maximum binding with 2.5 microL/mL SGA serum vs 14 +/- 3% for sham serum, p less than .001), and correlated with fetal weight (r = -0.539, p less than .05) and insulin (r = -0.622, p less than .05). Ligand blotting with [125I]IGF-I revealed that serum levels of IGFBP-1 (32 K) were greater in SGA than shams, while immunoblotting with specific antiserum demonstrated that levels of IGFBP-2 (34 K), the major fetal rat IGF BP, were similar in serum from SGA and shams litters. Affinity labeling and immunoprecipitation confirmed that IGF binding activity is increased in SGA, due largely to increased availability of IGFBP-1. In addition, Northern analysis of hepatic RNA revealed that the abundance of IGFBP-1 mRNA is increased in the SGA fetal rat, while hepatic mRNA for IGFBP-2 is similar in SGA and sham-operated litters. We conclude that circulating levels of IGFBP-1 and the abundance of hepatic mRNA are increased in the SGA fetal rat. IGFBP-1 may be an important modulator of IGF bioactivity and somatic growth in utero.

Pneumothorax in the respiratory distress syndrome: incidence and effect on vital signs, blood gases, and pH.

We determined the incidence of pneumothorax in 295 infants (mean birthweight, 1,917 gm) with the respiratory distress syndrome (RDS) treated according to the same protocol. Fifty-five infants (mean birthweight, 1,594 gm) developed pneumothorax (incidence, 19%); incidence varied with severity of RDS and intensity of respiratory assistance. Pneumothorax occurred in 3.5% (2 of 58) of infants who received no assisted ventilation and in 11% (14 of 124) of infants who received continuous positive airway pressure (CPAP) as the only form of assisted ventilation; the difference between these two groups is not significant. Forty-nine infants initially treated with CPAP later required mechanical ventilation with positive end-expiratory pressure (PEEP). Pneumothorax occurred in 12 of the 49 (24%) and in 21 of 64 (33%) of those infants initially treated with PEEP; the incidence of pneumothorax for both these groups was significantly higher than for those treated with no assisted ventilation or CPAP only. To assess the value of frequent measurement of vital signs, blood gas tensions, and pH in the recognition of pneumothorax, we analyzed these variables by the cumulative sum statistical technique. We noted the following significant changes associated with pneumothorax: arterial blood pressure, heart rate, and respiratory rate decreased in 77% of cases; pulse pressure narrowed in 51% of cases; Po2 decreased in 17 of 20 cases in which ventilatory settings were constant for at least three hours prior to pneumothorax. However, pH and Pco2 showed consistent changes. Frequent measurements of vital signs and Po2 aid in the early diagnosis of pneumothorax.

Rapid measurement of blood pressure in the sick neonate.

We measured mean arterial blood pressure using a hydrostatic technique in 24 sick neonates who had umbilical artery catheters in place. Value for blood pressure obtained with this technique correlated significantly (r = 0.9844, P less than 0.01) with measurements obtained with standard strain gauge and electronic monitor. The method is simple, quick, and safe. It is particularly useful when the infant's size or clinical condition precludes the use of the sphygmomanometer or Doppler ultrasound device or in a setting, such as during transport, when standard electronic means of blood pressure measurement are unavailable.

Insulin injection in the fetal rat: accelerated intrauterine growth and altered fetal and neonatal glucose homeostasis.

Fetal hyperinsulinemia is a well-known correlate of accelerated fetal growth; the consequences of fetal hyperinsulinemia upon fetal and neonatal glucoregulation are less well understood. We injected rat fetuses of a litter on day 18 of gestation with either 5 units of long acting insulin (I) or 154 mmol/L NaCl. Twelve hours after injection, the wet and dry mass of total body and liver of I fetuses significantly exceeded that of controls. At birth (day 21.5), newborn I pups weighed 5.86 +/- .08 g, and controls, 5.48 +/- .05 g, (P less than .001). On day 18, within one hour of injection, fetal plasma insulin concentrations were significantly elevated and remained so for 24 hours. Mothers of I fetuses had significant elevations of plasma insulin at 1, 3, and 6 hours, and they developed transient hypoglycemia. Plasma glucose concentrations in I fetuses were significantly diminished at 1, 3, and 6 hours and then achieved control levels by 12 hours. Fetal hypoglycemia resulted from an apparent direct effect of insulin upon fetal tissue and from the maternal hypoglycemia. Hypoglycemic I fetuses demonstrated a sluggish alpha-cell response; they failed to increase plasma glucagon one hour after insulin injection. Values were significantly increased three hours after injection. At birth, I pups became hypoglycemic relative to controls. This was, in part, due to their significantly elevated plasma insulin concentrations at 120 and 240 minutes (120 minutes, 43.8 +/- 8 v 17.5 +/- 6 microU/mL, P less than .001). Plasma glucagon was significantly increased in I pups at 240 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate metabolism in pregnancy XVI: longitudinal estimates of the effects of pregnancy on D-(63H) glucose and D-(6-14C) glucose turnovers during fasting in the rat.

We measured blood glucose concentrations and glucose turnover rates in 24 hr fasted, conscious, unrestrained pregnant rats and nongravid controls on days 18, 19, and 20 of gestation. Turnover measurements were secured with simultaneous equilibrium infusions of D-(6-3H) and D-(6-14C) glucose so that gluconeogenic recycling could also be determined. "Steady state" values for blood glucose in the mother after 24 hr of fasting did not significantly differ on each of the days, and these concentrations were significantly lower than the values in 24 hr fasted nongravid rats. At 18 days gestation, glucose turnover did not differ from nongravid values. By contrast, values for glucose turnover after 24 hr fasting increased significantly and progressively in the 19 and 20 day pregnant rats. The increase in turnover correlated with the increasing growth of the conceptus. The ratio between D-(6-14C) glucose and D-(6-3H) turnover remained constant (and the same as in the nongravid rats) during all 3 days of gestation suggesting that rates of glucose recycling remained unaltered. These longitudinal studies indicate that the factors contributing to the pattern of "accelerated starvation" during dietary deprivation in pregnancy may vary as pregnancy progresses. The exaggerated lowering of blood glucose which accompanies fasting occurs before total glucose turnover increases. This could provide a potential mechanism for conserving maternal glucose. Since transplacental transfer of glucose is concentration-dependent, the early establishment of a lower "steady state" for circulating glucose could diminish the magnitude of loss of this key nutrient to the fetus.

Altered gas exchange, limited glucose and branched chain amino acids, and hypoinsulinism retard fetal growth in the rat.

We measured several growth stimulating variables in growth retarded (small-for-gestational-age [SGA]) rat fetuses on days 18, 19, 20, and 21 of their 21.5-day gestation. Bilateral maternal uterine artery ligation on day 18 was used to retard fetal growth, and fetuses of sham and nonoperated (normal) mothers served as controls. SGA fetuses had the lowest body and placental weights, while sham fetuses had intermediate weights from days 19 to 21. Similarly, SGA fetuses had the most profound alterations in arteriovenous PO2, PCO2, and pH, while sham fetuses had significant but less severe alterations. Fetal plasma concentrations and fetal/maternal ratios of glucose were significantly diminished in SGA fetuses on days 18 and 19; sham fetuses had intermediate values on day 19. Plasma concentrations and fetal/maternal ratios of leucine, isoleucine, and valine, but not the other amino acids, were significantly diminished in SGA fetuses on days 18, 19, and 20. Plasma insulin concentrations were significantly diminished in SGA fetuses on days 19 and 20, and hepatic concentrations of glycogen were significantly diminished on all days. Despite significantly elevated plasma glucagon concentrations in SGA fetuses, hepatic cytosolic phosphoenolpyruvate carboxykinase (PEPCK) activity was not elevated. These data indicate that bilateral uterine artery ligation retards fetal growth in the rat by altering gas exchange and limiting fuel availability. The limited insulin in SGA fetuses might further have retarded growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic maternal hypoxia retards fetal growth and increases glucose utilization of select fetal tissues in the rat.

The development of intrauterine growth retardation (IUGR) is frequently associated with fetal hypoxia, hypoglycemia, and abnormal fetal glucose metabolism. To determine the effects of hypoxia (without concomitant hypoglycemia) on fetal glucose metabolism, we continuously exposed pregnant rats to 10% (10.1 kPa) ambient oxygen from day 15 through day 20 of gestation (term, 21.5 days) and used radiolabeled 2-deoxyglucose (2DG) to measure in vivo relative glucose utilization (rGU) of several fetal tissues on day 20 of gestation. Pair-fed rats in room-air oxygen were used as controls. Maternal hypoxia resulted in significant IUGR, fetal hypoxia and acidosis, and fetal lactate accumulation on day 20 of gestation. Following 5 days of hypoxia, rGU values for fetal lung, heart, and kidney were increased by 61%, 54%, and 47%, respectively (P < .05). rGU values for fetal brain, liver, muscle, and placenta were not significantly affected. Fetal plasma glucose concentrations were similar in hypoxic and control fetuses. We speculate that the increased rGU of hypoxic fetal tissues is due in part to anaerobic metabolism and increased glycolysis.

Carbohydrate metabolism in the fetus and neonate and altered neonatal glucoregulation.

Altered glucose homeostasis in the neonate often results from antecedent events during fetal life. This article describes the normal and altered development of glucoregulatory capabilities during perinatal life and relates it to problems of hypo- and hyperglycemia in the neonate.

Caval catheterization in the intensive care nursery: a useful means for providing parenteral nutrition to the extremely low birth-weight infant.

We provided parenteral nutrition to 40 very low birth-weight premature infants (birth weight 815 +/- 17 grams, gestational age 27 +/- 2 weeks) with a superior vena cava catheter. To avoid the risk of transport, catheterization was performed under sterile conditions in the intensive care nursery. The central venous catheter facilitated administration of calories to sustain growth, especially in infants whose catheters remained in place for 3 weeks or longer. The overall incidence of catheter related sepsis was high (30%) but the majority of cases were due to Staphylococcus epidermidis and resolved without incident. Other complications of parenteral nutrition were minimal. This approach is a safe and effective means of providing nutrition to the very low birth-weight infant.