A comparison of birth weight and weight/length ratio for gestation as correlates of perinatal morbidity

OBJECTIVE

The purpose was to evaluate a low weight to length ratio as a correlate of perinatal morbidity and mortality.

STUDY DESIGN

Data from the Collaborative Perinatal Project for infants of 34 weeks' gestation or more were evaluated. Associations between the weight to length ratio of < 10% (low weight to length) and birth weight of < 10% (small for gestational age) by gestational age and gender, perinatal depression, dysmaturity, cerebral palsy, and neonatal mortality were evaluated.

RESULTS

A low weight to length ratio and small for gestational age status were associated with most markers of perinatal morbidity and mortality in term and preterm infants. In infants not small for gestational age, a low weight to length ratio was associated with increased morbidity and mortality (relative risk of 1.9 to 4.2) in term infants, and with perinatal depression (relative risk of 2.9) in preterm infants. Logistic regression found low weight to length ratio was a better independent correlate than small for gestational age status for all markers assessed and found low weight to length ratio was significantly associated with all morbidity and mortality markers in infants not small for gestational age.

CONCLUSION

Low weight to length ratio, a marker for asymmetric growth restriction, is correlated with perinatal morbidity, even in infants not small for gestational age.

Fas expression in pulmonary alveolar type II cells

Fas, a type I membrane receptor protein, transduces a signal culminating in apoptosis after binding to the Fas ligand. Information regarding the expression of Fas in nonlymphoid tissues, although limited, suggests a role for Fas in epithelial progenitor cell populations. In this paper, we provide several lines of evidence indicating that the progenitor cell of the alveolus, the type II cell, displays restricted expression of Fas. We found 1) Fas gene expression in RNA derived from fresh isolates of primary rat type II cells; 2) restriction of Fas expression to a subset of alveolar type II cells by in situ hybridization and immunohistochemistry of the normal mouse lung; 3) induction of apoptosis in a mouse lung type II epithelial cell line (MLE) after activation of Fas; and 4) induction of apoptosis in a subpopulation of type II cells after the intratracheal instillation of an activating anti-Fas antibody in mice. These findings suggest that Fas-dependent apoptosis is involved in regulating turnover of the alveolar epithelium.

Simultaneous in situ hybridization and TUNEL to identify cells undergoing apoptosis

Apoptotic cells in tissue sections can be localized by in situ labelling of partly degraded DNA. In a heterogeneous population of cells, however, the specific identity of cell types undergoing apoptosis often cannot be reliably achieved at the light microscope level because of the marked alterations in cellular morphology that characterize apoptosis. In order to clearly specify cell types undergoing apoptosis, in situ end labelling has been coupled to immunohistochemistry. This method is limited by the availability of antibodies that bind to cell-specific protein markers in tissue sections. In contrast, we describe a method that combines in situ end labellin with in situ hybridization, a technique that specifies cell types based on mRNA expression. Taking advantage of the specific expression of surfactant protein C mRNA in type II alveolar epithelial cells, we demonstrate that this technique has the ability to localize alveolar type II cells undergoing apoptosis in vivo after the intratracheal instillation of an antibody that activates the cell surface Fas protein. The wide availability of cell-specific gene markers suggests that this method can be adapted to define cell types that undergo apoptosis during various physiological and pathological states in vivo.

Factorial structure of the Wisconsin Card Sorting Test

This study examined the factorial structure of the Wisconsin Card Sorting Test (WCST) in normal university students (N = 135) and a mixed clinical sample (N = 139). Two highly stable orthogonal factors were observed accounting for 70 and 21 per cent of the variance, respectively. Factor I was interpreted as reflecting undifferentiated executive function while Factor II may measure cognitive abilities associated with attentional function. This work can serve as the basis for further examination of the construct validity of the WCST and has implications for its use.

Cerebral palsy in infants with asymmetric growth restriction

The relationship between low ponderal index and cerebral palsy was evaluated. National Collaborative Perinatal Project and University of California Child Health and Development Study data were analyzed. Associations between low ponderal index (ponderal index < 5% for gestational age) were evaluated in the combined population, in term and preterm infants, and in non-SGA infants (with birth weights > 5% for gestational age and gender). Data from 55,571 infants, including 232 cases of cerebral palsy, were evaluated. Low ponderal index was significantly associated with CP in the delivery population (Relative risk 2.2) and in non-SGA infants (RR 1.9). Low ponderal index was a significant independent correlate of cerebral palsy (RR 1.9) in non-SGA infants after using logistic regression to correct for effects of prematurity and gender. Low ponderal index is associated with increased risk of CP, even in non-SGA infants. Assessment of the neonatal ponderal index provides an additional method of documenting prior abnormal fetal growth and development.

Nitrogen dioxide exposure activates gamma-glutamyl transferase gene expression in rat lung

Exposure to nitrogen dioxide (NO2) has been shown to activate glutathione metabolism in lung and lung lavage. Since GGT is a key enzyme in glutathione metabolism and we have previously characterized GGT expression in distal lung epithelium and in lung surfactant, we examined the NO2 exposed lung for induction of gamma-glutamyl transferase (GGT) mRNA, protein, and enzyme activity. We found that the GGT gene product is induced in lung by NO2. The GGT mRNA level in lung increases 2-fold within 6 hr and 3-fold after 24 hr of exposure to this oxidant gas, and this 3-fold elevation persists even after 14 days of exposure. The pattern of GGT mRNA expression switches from the single GGT mRNA III transcript in the normal lung to the dual expression of GGT mRNA I and mRNA III. Enzyme activity in whole lung increases 1.6- to 2.5-fold while extracellular surfactant-associated GGT activity accumulates 5.5-fold and GGT protein accumulates in lung surfactant. Induction of GGT mRNA and protein is evident in cells of the bronchioles by in situ hybridization and immunolocalization, respectively. In contrast, alveolar type 2 cells lack an in situ hybridization signal and exhibit a reduction in the intensity of immunostaining with prolonged exposure. Our studies show that NO2 induces GGT mRNA expression, including GGT mRNA1, in lung and GGT protein and enzyme activity in lung and lung lavage in response to the oxidative stress of NO2 inhalation.

Ontogeny of gamma-glutamyltransferase in the rat lung

gamma-Glutamyltransferase (gamma-GT) is a key enzyme in the metabolism of glutathione and glutathione-substituted molecules. The gamma-GT gene is expressed in two epithelial cells of the adult lung, the bronchiolar Clara cell and the alveolar type II cell. Because pulmonary glutathione metabolism may be important in the perinatal period, we studied gamma-GT ontogeny in the developing rat lung. In the late fetal and early postnatal lung, gamma-GT mRNA was below detectable limits on Northern blots. Pulmonary gamma-GT protein and enzyme activity were present at low levels after fetal day 18. gamma-GT protein appeared as a high-molecular-mass band (>95 kDa), with small amounts of enzymatically active gamma-GT heterodimer. Between the 2nd and 3rd postnatal wk, pulmonary gamma-GT mRNA expression increased in association with an increase in gamma-GT protein and enzyme activity that reached adult lung levels. At this time, gamma-GT protein appeared predominantly in the heterodimeric form with small amounts of the >95-kDa protein. Immunocytochemistry revealed that, in the fetal and early postnatal lung, gamma-GT was expressed only in the alveolar type II cell, whereas the Clara cell became the major site of gamma-GT mRNA and protein expression by 2-3 wk and in the adult. Type II cells isolated from the fetal lung express gamma-GT mRNA and synthesize the >95-kDa form of gamma-GT in excess of the heterodimer. These studies demonstrate that the alveolar type II cell is the only cell producing gamma-GT in the newborn lung and that it synthesizes a form of gamma-GT that appears to differ from that produced at a later time point by the Clara cell.

Forensic examination of a mouse allegedly found in a previously sealed can of milk stout

A mouse carcase, allegedly found in a can of commercial milk stout sealed 3 months previously, was examined. Because of uncertainty as to the time of death of the mouse, a pilot trial, designed to determine whether the mouse had been canned simultaneously with the milk stout, was performed. Twelve mice were killed, and canned in 450 ml beer cans. After periods varying from 1 day to 3 months the cans were opened and the state of decomposition of the mice was recorded. By comparing the state of the submitted mouse with that of the experimental mice it was established, without doubt, that the submitted mouse could not have been in the can at the time the consumer had opened it.

Epithelial marker genes are expressed in cultured embryonic rat lung and in vivo with similar spatial and temporal patterns

Explants of embryonic lung are often used to characterize lung growth, bronchial tree pattern, and cell differentiation. Most investigators culture lungs for 3-7 days in defined media lacking, e.g., added growth factors or hormones. If growth and differentiation are comparable to that in vivo, these cultures show considerable promise for identifying developmental regulatory molecules and target genes, and for elucidating molecular responses. We used in situ hybridization and RT-PCR to compare times and sites of expression of mRNAs of six epithelial genes in cultured and uncultured fetal rat lungs. These genes, expressed in distal lung of adult rats, are surfactant proteins (SP) A, B, and C; LAR, a receptor-type tyrosine phosphatase; Clara cell secretory protein (CC10, CCSP); and T1alpha. SP-A, SF-B, LAR, and CC10 are expressed by both Clara and Type II cells in adult animals. SP-C and T1alpha are unique markers for Type II and Type I cells, respectively. SP-C, LAR, and T1alpha are expressed before the lung is explanted (Day 13.5); SP-A, -B, and CC10 mRNAs are first detected later. The onset of expression is similar in vivo and in vitro. Although the patterns of expression differ for each mRNA, their sites of expression in culture match those in vivo relative to the bronchial tree. The explanted embryonic lung appears to be an excellent experimental model.

Retinoic acid alters the expression of pattern-related genes in the developing rat lung

Exogenous retinoids alter pattern formation and differentiation in many developing systems, such as limb, vertebrae, and central nervous system. Many of these effects are mediated by changes in expression of patterning genes such as Hox genes and Sonic hedgehog. We have previously shown that exogenous retinoic acid, administered to the embryonic rat lung in culture alters the structural pattern of the developing lung, suppressing formation of distal lung and favoring growth of proximal tubules. To determine whether these retinoic acid-induced changes in lung development were linked to alterations in pattern-related genes, we characterized the expression of Hoxa-2, Hoxb-6, and Sonic hedgehog mRNAs in vivo and in vitro, with or without 10(-5)M retinoic acid, by in situ hybridization and quantitative polymerase chain reaction. Each of these genes demonstrated unique timing and distribution of expression that was similar in vivo and in control cultured embryonic lungs. Hoxb-6 and Sonic hedgehog mRNAs both decreased during lung development in vivo or in vitro. From the patterns of mRNA expression we propose that Hoxb-6 is involved in distal airway branching while Hoxa-2 is involved in differentiation of proximal mesenchymal derivatives and vasculogenesis in the lung. RA upregulated all three genes, changing their developmental pattern of distribution and preventing the developmental decrease in Sonic hedgehog expression. We propose that RA acts to maintain high levels of expression of these and likely other pattern-related genes in a fashion that is characteristic of the immature lung, promoting continued formation of proximal lung structures and preventing formation of typical distal lung structures of the mature lung.

Cerebral palsy, perinatal depression and low ponderal index

To determine whether asymmetric growth restriction, abnormally lean body morphology, is associated with cerebral palsy (CP) in infants born with perinatal depression, perinatally depressed Collaborative Perinatal Project infants were assessed. Rates of ponderal index less than 5% for gestational age and race (low PI), a marker for asymmetric growth, were compared in infants either neurologically normal or having CP at 7 years of age. Low PI was associated with CP in infants with Apgar scores of 0 to 3 at 10, 15 or 20 minutes in both of these groups, after exclusion of small-for-gestational-age infants, and was a significant individual correlate of cerebral palsy with multiple logistic regression. The attributable risk of cerebral palsy related to low Pl was 12.4%.

T1 alpha protein is developmentally regulated and expressed by alveolar type I cells, choroid plexus, and ciliary epithelia of adult rats

T1 alpha is the first marker gene known to be expressed in the adult lung solely by the alveolar type I epithelial cell. Previous studies showed that T1 alpha transcripts are abundant in early rat embryos where they are found in the nervous system and in the foregut and certain of its derivatives including the primitive lung. By mid- to late gestation T1 alpha messenger RNA (mRNA) expression is lost from neural tissues but appears to increase in the lung throughout fetal life. To determine whether the T1 alpha transcripts are translated into protein, especially in early embryos which sometimes express transcripts that are translationally silent, we performed immunohistochemistry on embryos and fetal tissues and analyzed certain tissues by western blotting using a monoclonal antibody against T1 alpha protein. T1 alpha protein is present at all sites that have previously been shown to express the mRNA and at similar developmental stages. As estimated from western blots, T1 alpha protein abundance peaks at about fetal day 16 in the brain and decreases thereafter to a relative level in the adult that is lower than that of the neural tube of the day 13 embryo. Relative protein abundance in the lung is very low, although detectable, on embryonic day 13 but increases slowly until fetal day 20 when there is a dramatic increase. At the time of birth, restriction to the type I cell is not complete and therefore must occur during postnatal lung development. Immunostaining reveals additional sites of expression in fetal and adult rats that had not been clearly visualized in previous in situ hybridization studies. T1 alpha is present in mesonephric tubules and apparently in primitive germ cells but is not detectable in specific cells in the adult kidney, ovary, or testis. However, cells of the choroid plexus of the central nervous system and the ciliary epithelium of the eye express T1 alpha in both fetuses and adults. The well-known functions of these epithelia are to elaborate cerebrospinal fluid and aqueous humor respectively by processes of active ion transport and water fluxes, probably through the aquaporin 1 (channel-forming integral membrane protein [CHIP] 28). We speculate therefore that T1 alpha protein may modulate or participate in these types of cellular functions in the lung.

On a failure to replicate: methodologically close, but not close enough. A response to hogben et al

Williams, Brannan and Lartigue (1987) (Clinical Vision Science, 1, 367-371) reported that poor readers took significantly longer to search letter arrays for a target than did good readers. In addition, they reported that blurring the letter arrays leads to faster search times for poor readers and a loss of the significant differences between the groups seen with unblurred displays. In a recent attempt to replicate these findings, Hogben et al. (1996) (Vision Research, 36, 1503-1507) found no differences in search rates between good and poor readers using unblurred arrays, and no differences in search rate between the groups when blurred arrays were used. In the present article, we have compared these two research efforts, and a third paper on the same topic, with regard to methodological factors in an attempt to understand how these two different results could occur. It is our belief that the letter spacing employed in the two studies may account for the difference and should be the focus of future studies of the original effect.

Type I receptor serine-threonine kinase preferentially expressed in pulmonary blood vessels

Type II and type I receptor serine-threonine kinases (RSTK) are important components of the transmembrane signaling machinery that allow cells to respond to the transforming growth factor-beta (TGF-beta) superfamily of cytokines. We have cloned from rat lung and report here a 3,935-base pair (bp) cDNA encoding a type I RSTK previously identified as R-3 (rat) or ALK-1 (human). Northern blot analysis reveals that the R-3 mRNA is more abundant in lung than in other adult rat tissues. With the use of in situ hybridization, the R-3 transcripts are found exclusively in the pulmonary vessels of all sizes, as well as in aorta, vena cava, and certain blood vessels of kidney, spleen, heart and intestine. In most blood vessels, a higher level of gene expression is found in endothelium than in adjacent smooth muscle. The R-3 transcripts are also found in splenic macrophages, as well as within cells of marginal zone of the splenic lymphoid tissue. In fetal rat lung, the expression of R-3 transcripts differs from the expression patterns of two other type 1 RSTK. The R-3 is expressed in vessels; the activin type IB receptor (R-2) is preferentially expressed in putative developing airways, whereas the TGF-beta type I receptor (R-4) transcripts appear to be ubiquitous. Our data suggest that in vivo R-3 may propagate signaling of TGF-beta in selected cell types. The differential expression of multiple type I receptors within different cell lineages may therefore define cell specific responses to TGF-beta.

The role of attention in Wisconsin Card Sorting Test performance

The present study sought to test the hypothesis that the second factor (consisting of Failure-to-Maintain-Set and other scores) found in two recent factor analyses of the Wisconsin Card Sorting Test reflects attentional function. The effect of color overlays (an experimental manipulation known to influence neural systems linked to attention) was examined in 17 normal control and 14 attention-disordered children (ages 8 to 12). Group and Color main effects were found for Factor 1 (which consists largely of measures of perseveration) and a Color main effect was observed for Factor 2. The Color effect for Factor 2 supported the contention that this factor reflects attentional processes. A hypothesis concerning the relationship between problem solving and attention on the WCST is offered and a means for testing it is discussed.

Vacuum-assisted delivery

The literature seems to allow certain general conclusions regarding the choice of instrument for assisted vaginal delivery. Both forceps and vacuum extraction offer certain advantages and drawbacks. Forceps are more difficult to apply, more prone to potentially significant facial injuries, require generally better maternal analgesia, and are associated with increased maternal soft tissue trauma. Vacuum extractors in general are easier to apply, are more likely to result in scalp trauma, and may be associated with increased rates of intracranial trauma. It seems likely that factors particular to each patient may play a significant role in the genesis of delivery associated with maternal and neonatal morbidity. Because of the ease of application, vacuum extractors may be used potentially in circumstances in which forceps assistance would not be attempted, allowing an operator of average experience to perform rotational deliveries. The use of vacuum extraction does appear to decrease the incidence of cesarean section in delivery populations. Given the apparent association between difficult assisted deliveries and increased neonatal morbidity, it is incumbent on the operator to attempt delivery only when vaginal delivery seems to be a safe option. Furthermore, the operator in such circumstances must be willing to reassess the attempt if initial attempts are not met with success. The minimal rates of significant intracranial injury associated with vacuum extraction in randomized studies of the method demonstrate the relative safety of the vacuum extraction when used judiciously. The ultimate choice of the route of delivery and method of assisted delivery should reflect a consideration of the fetal station, presentation, and maternal and fetal circumstances. It is hoped that further investigations in this area may clarify some of the issues discussed in this article.

Expression of insulin-like growth factor receptors 1 and 2 in the developing lung and their relation to epithelial cell differentiation

Insulin-like growth factors (IGFs) and their receptors have been implicated as regulators of cell differentiation and cell proliferation in a number of systems and have been shown to play an important role in embryonic development. In this study we examined expression of mRNA for IGF-I and IGF-II, IGF binding protein 2 (IGFBP-2), and IGF receptors 1 (IGFR-1) and 2 (IGFR-2) during fetal lung development and in early postnatal and adult lungs by the polymerase chain reaction (PCR). IGF-I mRNA was found in embryonic and postnatal lungs at all ages as was IGFBP-2, whereas IGF-II mRNA was present only in prenatal lungs. IGFR-1 was present in all but the adult lungs. Lung epithelial cells expressed IGFR-1 at 14 days' gestation but not at 18 days' gestation as measured by PCR and in situ hybridization. Alveolar epithelial cells re-expressed IGFR-1 mRNA in the early postnatal period but not in the adult lung. IGFR-2 was expressed by PCR and in situ hybridization in 14-day embryonic epithelium, was not present at 18 days or at birth, but was re-expressed at high levels in the early postnatal alveolar wall. Immunocytochemical localization of IGFR-2 confirmed its absence in the late fetal and newborn lung. It reappeared in alveoli, exclusively in type 1 cells, in early postnatal and adult lungs. These studies demonstrate the stage- and cell-specific appearance of IGF receptors in the developing and postnatal lung. They also establish IGFR-2 as a marker of the mature alveolar type 1 cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Two closely related receptor-type tyrosine phosphatases are differentially expressed during rat lung development

Transmembrane protein tyrosine phosphatases (PTPases) comprise a newly identified class of receptor-like molecules. In most cases their ligands and the substrates they dephosphorylate are not known. In order to begin to explore the functions of the PTPases in cell physiology and in mammalian development, we examined the expression patterns of two closely related receptor-type tyrosine phosphatase genes, namely LAR and PTP delta, in fetal rat lung and in selected adult rat tissues. In the lung, in situ hybridization and immunohistochemistry show that the LAR mRNA and protein are expressed exclusively in the epithelium. In the early embryonic or fetal lung (day 13 to 18) LAR is expressed by all of the epithelial cells of the forming bronchial tree. This widespread pattern of expression is lost later in fetal life (day 21) as the lung matures and acquires the morphologic and biochemical features of the adult organ. LAR gene expression is then confined to two epithelial progenitor cells of the distal airways, namely the bronchiolar Clara cell and the alveolar type II cell. The LAR gene products were also found abundantly expressed in epithelial progenitor cells of adult esophagus, skin, and small intestine, all of which are continuously renewing epithelia. The rat PTP delta gene, on the other hand, is specifically expressed in the mesenchyme of the developing lung. The level of the PTP delta mRNA decreases as the lung matures. These results suggest that the two closely related receptor-type tyrosine phosphatases are differentially expressed in a tissue-specific fashion. They are expressed mostly in proliferating cells or in cells which have potential to proliferate.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of sample preparation and storage on maternal triple-marker screening

OBJECTIVE

To evaluate the effect of different sample collection, storage, and preparation techniques on serum alpha-fetoprotein (AFP), beta-hCG, and unconjugated estriol (E3) concentrations.

METHODS

A solution containing known concentrations of AFP, hCG, and unconjugated E3 was diluted in blood samples obtained from seven healthy male volunteers. Serum from each blood sample was removed immediately, and either assayed or frozen at -70C. Portions of the remaining blood were handled as follows: centrifuged and refrigerated, centrifuged and left at room temperature, not centrifuged and refrigerated, or not centrifuged and left at room temperature. Serum was removed from these samples for triple-marker analysis at 24, 48, 96, and 168 hours after the initial sample collection.

RESULTS

Immediate freezing of serum and subsequent thawing resulted in a significant increase in beta-hCG and unconjugated E3 levels, but no change in AFP levels. There was a significant effect over time on AFP, hCG, and unconjugated E3 concentrations. The change in AFP levels was influenced by centrifugation status, whereas all three analytes were influenced by refrigeration status.

CONCLUSION

Different sample collection, storage, and preparation techniques may affect maternal triple-marker screening.

Retinoic acid induces changes in the pattern of airway branching and alters epithelial cell differentiation in the developing lung in vitro

Retinoids have been shown to influence pattern formation during development and regeneration in numerous systems such as limbs, vertebrae, and neural tube although there is little information about the effects of retinoids on pattern formation in visceral organs. We investigated the effects of exogenous retinoic acid on the in vitro pattern of airway branching and on lung epithelial cell differentiation. Histology, [3H]thymidine autoradiographies and reverse transcriptase/polymerase chain reaction (RT/PCR) amplification were used to assess the effects of retinoids and the expression of lung epithelial markers of differentiation. We found that retinoic acid interferes, in a dose-dependent fashion, with the expression of epithelial genes that are found in distal segments of the fetal lung (surfactant-associated proteins SP-A, SP-B, and SP-C). At high concentrations, retinoic acid (RA) dramatically altered the developmental pattern of the lung, favoring growth of structures that resemble proximal airways and concomitantly suppressing distal epithelial buds. We hypothesize that this in vitro "proximalizing" effect on the developing lung may be related to alterations in the expression of pattern-related genes.

Pre-induction cervical ripening: a randomized comparison of two methods

OBJECTIVES

To compare two methods of pre-induction cervical ripening in a randomized clinical trial.

METHODS

A single intracervical prostaglandin E2 (PGE2) gel application was compared with a single insertion of hygroscopic dilators in 441 women at term with unfavorable cervical scores. Induction success was defined as entry into active labor within 6 hours of oxytocin infusion.

RESULTS

There was no statistical difference in pre- or post-ripening cervical scores. In the group receiving hygroscopic dilators, only 28% entered the active phase of labor within 6 hours of oxytocin infusion compared with 45% (P < .001) in the PGE2 group. Thus, in this study, a change in cervical score did not directly predict induction success. There was a higher rate of postpartum endometritis (24 versus 14%; P = .007) and suspected neonatal infection (10 versus 5%; P = .03) in the dilator group.

CONCLUSIONS

Pre-induction ripening by hygroscopic dilators and intracervical PGE2 was equivalent as measured by changes in the cervical score. The change in cervical score, however, was not predictive of successful induction, and PGE2 was more frequently associated with induction success. Hygroscopic dilators were associated with a higher incidence of postpartum maternal and neonatal infection because of a longer duration of labor. Hospital charges for intracervical PGE2 gel totaled $522 compared with $91 for the insertion of three dilators.