Don B. Singer

The lung in cystic fibrosis: A quantitative study including prevalence of pathologic findings among different age groups

The autopsies of 82 patients with cystic fibrosis were reviewed with respect to pathologic changes in the lungs and their respective prevalence among different age groups. Although bronchitis, mucopurulent plugging, and bronchopneumonia were almost universally present among children of all ages, epithelial metaplasia and bronchiectasis were rarer among infants and progressively more prevalent in older age groups. Emphysema was absent in patients under two years of age and affected 11 per cent of the patients two to six years of age and 40 per cent of the patients older than six years, but was never of a severe degree by the point count method. Pulmonary hemorrhage, although uncommon, was usually associated with prominent arterial vessels in walls of bronchiectatic airways. Quantitative assessment of bronchial glands revealed Reid indices significantly higher in patients with cystic fibrosis when compared to noncystic fibrosis patients, but there was no increase in these indices with the age of the patients. Glandular hypertrophy, predominance of mucous acini within glands, and goblet cell hyperplasia of the bronchial mucosa all suggest an explanation for the copious mucous secretion of patients with cystic fibrosis. However, it was not possible to ascertain whether these findings reflect a general exocrine defect of such patients or whether they were merely a response to chronic airway infection, even though the latter is a more plausible assumption.

Increased erythropoiesis and elevated erythropoietin in infants born to diabetic mothers and in hyperinsulinemic rhesus fetuses.

The pathogenesis of the increased erythrocytosis and extramedullary erythropoiesis observed in infants of diabetic mothers (IDM) has been obscure. In the present studies, IDM were found to have elevated umbilical plasma erythropoietin (Ep) concentrations by radioimmunoassay. 22 of 61 IDM (36%) had levels above the range of 28 nonasphyxiated, appropriately grown normal infants. In 16 controls and 20 IDM, plasma Ep correlated directly with plasma insulin (P less than 0.001, r = 0.73). To investigate this relationship further, a chronic rhesus model was studied with continuous fetal hyperinsulinemia for 21 d in utero in the last third of pregnancy. In five experimental fetuses, plasma insulin levels averaged 4,210 microU/ml at delivery, whereas plasma Ep was above the range of six controls. In addition, the experimental fetuses had elevated reticulocyte counts in umbilical cord blood. The mechanism for the increased plasma Ep associated with hyperinsulinemia in the fetus is unexplained but may be mediated by fetal hypoxia.

Asplenic-hyposplenic Overwhelming Sepsis: Postsplenectomy Sepsis Revisited

Absence of the spleen or splenic function predisposes individuals to risk of overwhelming infection. These infections are most often due to encapsulated organisms, especially pneumococcus, Haemophilus influenzae type b, and meningococcus, but any bacterial agent may cause the rapid onset of septicemia, meningitis, pneumonia, and shock characteristic of the asplenic-hyposplenic condition. The risk is greatest in infants and young children, but asplenic-hyposplenic adults also have an increased risk of infection. Prophylactic antibiotics and immunization with polyvalent pneumococcal, H. influenzae type b, and meningococcal vaccines have reduced the incidence of infections in asplenic-hyposplenic individuals, but even these measures have not eliminated the risk. Surgeons have adopted techniques to save as much splenic tissue as possible and some splenic functions, such as pitting red cells, have been preserved, but conservative surgery has not provided total protection against overwhelming infection. Therapies designed to interrupt the cascade of overwhelming sepsis have not yet been successful.In those cases in which the spleen is surgically removed, the underlying disease or condition leading to splenectomy influences the risk of sepsis. Splenectomy incidental to other operations, such as gastrectomy, results in the lowest risk for overwhelming infection, but this is still some 35-fold greater than the risk for overwhelming infections in the general population. In increasing order of risk, the other main indications for surgical removal of the spleen are idiopathic thrombocytopenia purpura, trauma, transplantation procedures, hereditary spherocytosis, staging Hodgkins disease, portal hypertension with hypersplenism, and thalassemia. Pathologists should comment on the risk of overwhelming sepsis when spleens are processed as surgical specimens, and should carefully weigh all splenic tissue, including accessory spleens and splenic implants (splenosis), in autopsy cases with and without overwhelming sepsis.

Chronic Hyperinsulinemia in the Fetal Rhesus Monkey: Effects on Fetal Growth and Composition

The delivery of 19 U of insulin a day for 21 days to the rhesus monkey fetus, coupled with the permeability properties of the placenta, has made it possible to produce fetal hyperinsulinemia in the presence of euglycemia. Fetal plasma insulin concentrations of 3525 μU/ml were attained with no apparent effects on the mother. In fetal macrosomia, a 34% increase in body weight was observed above the expected weight for gestational age (466 vs. 348 g). Relative organomegaly, matched for gestational age of fetal weight, was seen in the hyperinsulinemic fetuses with enlarged livers, placentas, hearts, and spleens. Liver composition in the fetuses was only slightly affected by hyperinsulinemia. Glycogen concentration was elevated, but not sufficiently, to explain the relative hepatomegaly produced. The lipid, protein, DNA, and RNA concentrations were not affected by hyperinsulinemia. Based on the similar DNA concentrations and protein/DNA ratios observed in hyperinsulinemic and control groups, the hepatomegaly appears to be the result of insulin-stimulated hyperplasia and not of hypertrophy. In the presence of normal plasma concentrations of growth substrates, insulin in the subhuman fetus has been shown to be a growth-promoting hormone that has specific growth-stimulating effects.

Reference Values for Singleton and Twin Placental Weights

The largest series of normal singleton placental weights was collected in the Collaborative Perinatal Study between the years 1959 and 1966 but values for normal twin placental weights were not published. In our study we examined 787 singleton and 514 twin normal placentas. Placentas with associated conditions known to affect the weights of placentas were excluded. After establishing the normal values for singleton and twin placental weights, we concluded that weight gain of twin placentas appears to accelerate between 24 and 36 weeks but reaches a plateau after 37 weeks, whereas singleton placentas appear to gain weight more uniformly throughout gestation. The mean values of twin placental weights for each gestational age are less than double those of singleton placental weights for the same duration of gestation. Our singleton and twin placentas are heavier than those from previously published data and may reflect a generational or nutritional change over the 30 years since the original numbers were compiled.

Congenital rubella encephalitis: Course and early sequelae†

Neurological abnormalities were noted at some time between birth and 18 months of age in 81 of 100 patients with congenital rubella infection. These included lethargy, full fontanel, irritability, and increased concentration of protein and persistence of virus in the cerebrospinal fluid. Of the 64 survivors 44 had a wide range of neurological abnormalities at 18 months of age including motor paresis, restlessness, motor mannerisms, and developmental delay. Retardation in growth, particularly of the head, was still manifest at 18 months. Pathological changes in central nervous system structures included leptomeningitis, vasculitis, and multifocal areas of parenchymal necrosis and perivascular calcification.

Chronic Hyperinsulinemia in the Fetal Rhesus Monkey: Effects of Physiologic Hyperinsulinemia on Fetal Growth and Composition

One of the hallmarks of the hyperglycemic-hyperinsulinemic infant of the diabetic mother (IDM) is macrosomia and selective organomegaly. Primary hyperinsulinemia, with insulin levels similar to those observed in human IDMs at delivery, was produced in the fetal rhesus monkey during the last third of gestation. The effects of this physiologically relevant hyperinsulinemia, in the absence of hyperglycemia, on fetal growth were studied. Fetal macrosomia, with a 23% increase in total body weight, was observed in physiologically hyperinsulinemic fetuses. A similar 27% increase in weight was produced by fetal insulin levels that were 10 times higher. A logarithmic correlation was observed between fetal birth weight ratio and fetal plasma insulin concentration. In contrast to this increase in weight, skeletal growth, as measured by crown-heel length and head circumference, was not affected by hyperinsulinemia. Only cardiomegaly was found in the low-dose hyperinsulinemic fetuses, whereas cardiomegaly, hepatomegaly, and splenomegaly were produced by hyperinsulinemia in which insulin levels were in the highest range. Compositional analysis of heart and skeletal muscle indicated no differences in the protein, RNA and DNA concentration, or in the protein-to-DNA ratio in hyperinsulinemic fetuses. We interpret these data as indicating that fetal insulin plays the predominant role in controlling the normal, as well as the augmented, fetal weight characteristic of the human infant of the diabetic mother.

Abnormalities of diaphragmatic muscle in neonates with ventilated lungs

Several infants and neonates who had received long-term ventilatory assistance had subnormal diaphragmatic muscle mass on gross necropsy examination. We conducted a retrospective study of our hospital infant necropsy files to determine whether prolonged ventilatory support was associated with diminution in myofiber cross-sectional area selectively affecting the diaphragm. We found that long-term ventilatory assistance may predispose diaphragmatic myofibers to disuse atrophy or to failure or normal growth. This phenomenon may contribute to difficulties in weaning infants from ventilatory support.

Central Nervous System Malformations in a Perinatal/Neonatal Autopsy Series

ABSTRACT Congenital malformations of the central nervous system (CNS) are among the most common anomalies, but data on the incidence of CNS malformations in autopsy populations are scant. We examined 4122 autopsies between the years 1958 and 1995. There were 363 cases (8.8%) with CNS malformations; 235 were neonates and 128 stillborns. The overall gender ratio was 1:1, although more male neonates and more female stillborns had malformations. The body weights ranged from 24 to 6440 g. Neural tube defects were the most common types of malformations (45.5%) and included anencephaly, meningoencephalocele, meningocele/meningomyelocele, craniospinal rachischisis, and spina bifida occulta. The incidences of other malformations were: congenital hydrocephalus (12.4%), neuronal/glial proliferation disorders such as micro- and macrocephaly (8.8%), neuronal migration disorders (8.8%), prosencephalon growth disorders such as holoprosencephaly and arhinencephaly (8.5%), abnormalities of the midline structures such as agenesis of corpus callosum (4.1%), developmental cysts (3.3%), cerebellar malformations (3%), and vascular malformations (2%). Miscellaneous malformations (3%) consisted of acephalia in four cases with twin reversed arterial perfusion (TRAP), two cases of hydranencephaly, and four cases of rare degenerative and metabolic encephalopathies.

The Role of Histone Acetylation in Regulating Early Gene Expression Patterns during Early Embryonic Stem Cell Differentiation

We have examined the role of histone acetylation in the very earliest steps of differentiation of mouse embryonic stem cells in response to withdrawal of leukemia inhibitory factor (LIF) as a differentiation signal. The cells undergo dramatic changes in morphology and an ordered program of gene expression changes representing differentiation to all three germ layers over the first 3-5 days of LIF withdrawal. We observed a global increase in acetylation on histone H4 and to a lesser extent on histone H3 over this time period. Treatment of the cells with trichostatin A (TSA), a histone deacetylase inhibitor, induced changes in morphology, gene expression, and histone acetylation that mimicked differentiation induced by withdrawal of LIF. We examined localized histone acetylation in the regulatory regions of genes that were transcriptionally either active in undifferentiated cells, induced during differentiation, or inactive under all treatments. There was striking concordance in the histone acetylation patterns of specific genes induced by both TSA and LIF withdrawal. Increased histone acetylation in local regions correlated best with induction of gene expression. Finally, TSA treatment did not support the maintenance or progression of differentiation. Upon removal of TSA, the cells reverted to the undifferentiated phenotype. We concluded that increased histone acetylation at specific genes played a role in their expression, but additional events are required for maintenance of differentiated gene expression and loss of the pluripotent state.