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A cDNA clone encoding a protein homologous to human bone morphogenetic protein 1 (huBMP1) was isolated from a sea urchin embryo cDNA library. This sea urchin gene, named suBMP, encodes a protein of Mr of 72×103. The deduced amino acid sequence of suBMP shares 72% sequence similarity (55% identity) with that of huBMP1. Like huBMP1 it also contains an N-terminal metalloendo-protease domain that shares sequence similarity with the astacin protease from crayfish, a C-terminal domain that is similar to the repeat domain found in C1r or C1s serine proteases, and an EGF-like segment. Although suBMP mRNA was detectable at a low level in the unfertilized egg, maximal expression of mRNA was observed at hatched blastula stage, with only a modest decrease in level at later stages of development. In situ hybridization studies revealed that suBMP mRNA is found in both ectodermal and primary mesenchyme cells in hatched blastula-stage embryos. Maximal expression of suBMP was observed at mesenchyme blastula, just before the onset of primitive skeleton (spicule) formation. SuBMP was found by immunoelectronmicroscopy in all cell types in late gastrula stage embryos. The antibody gold particles appeared in small clusters in the cytoplasm, on the surface of the cells and within the blastocoel. This distribution of suBMP, coupled with the finding that it was associated with membranes but was released by sodium carbonate treatment, suggests that the protein is secreted, and subsequently associates with a cell surface component. Two models for the possible function of suBMP in spiculogenesis in the sea urchin embryo are discussed.

Fecal soiling is a common complaint among school-age children. The fecal soiling is often accompanied by chronic constipation and so-called "idiopathic," "functional," or "psychogenic" megacolon, the cause of which is undetermined. The records of all children presenting to a pediatric gastroenterology clinic between 1981 and 1990 with difficult defecation were reviewed to determine the incidence of painful defecation and its relationship to chronic impaction and fecal soiling. There were 227 children; 74 were younger than 36 months of age and 153 were older than 36 months. Of the younger children, 86% presented with pain, 71% with impaction, and 97% with severe withholding. The younger children had painful defecation for a mean of 14 +/- 9 (SD) months before presentation. Of the older children, 85% presented with fecal soiling, 57% with pain, and 73% with fecal impaction, and 96% exhibited withholding; the older children had difficult defecation for a mean of 56 +/- 42 months before presentation. Sixty-three percent of the children presenting with fecal soiling had a history of painful defecation beginning before 36 months of age. Painful defecation frequently precedes chronic fecal impaction and fecal soiling in American children. Early, effective treatment of painful defecation in infancy might reduce the incidence of chronic fecal impaction and fecal soiling in school-age children.

The hepatic lesion in Reye's syndrome (acute encephalopathy with fatty degeneration of viscera) was studied by light microscopy of sequential biopsy specimens obtained in 49 children. The hepatic lesion is a morphologically characteristic, rapidly evolving, and reversible toxic hepatitis. In specimens obtained with 48 hr of onset of neurological deterioration, the severity of the diffuse microvesicular steatosis is best appreciated in frozen sections stained for lipid content. Variation in severity of hepatocyte glycogen depletion in early biopsies correlates with other histological measures of severity, and with the occurrence of hypoglycemia, severity of the encephalopathy at the time of admission, and mortality rate. Histochemical studies suggest that the hepatic lesion is attributable to mitochondrial injury and other evidence that supports this hypothesis is briefly reviewed. The etiology of the syndrome and its relationship to the viral disease which usually precedes it are unknown.

Five enzymes were measured in 50 liver specimens (18 normal liver, 20 Reye liver, 12 diverse liver disorders other than Reye syndrome). The enzymes were: glutamic dehydrogenase (E.C. 1.4.1.3), monoamine oxidase (E.C. 1.4.3.4), lactate dehydrogenase (E.C. 1.1.1.27), D-glucose-6-phosphate dehydrogenase (E.C. 1.1.1.49), catalase (E.C. 1.11.1.6). The Reye syndrome group showed significant decreases in glutamic dehydrogenase (56%) and monoamine oxidase (70%) compared to normal control tissue and these changes were not characteristic of the non-Reye liver disorder group as a whole. Neither catalase nor lactate dehydrogenase appeared to be altered significantly in the Reye or in the abnormal control group compared with normal controls. Thus, only the prominent decreases in the mitochondrial enzyme activities appeared to be highly characteristic of Reye syndrome. Paradoxically, the means of the five hepatic enzymes and the admission levels of two serum enzymes indicative of liver damage (alanine and aspartate aminotransferase) were remarkably similar for both survivors and nonsurvivors of Reye syndrome.

An infant was found to have abetalipoproteinemia, substantial hepatomegaly, and persistent elevation of the serum transaminases. Liver biopsies were obtained prior to treatment with medium chain triglyceride (MCT) and at 2, 14, and 20 months after initiation of treatment with the MCT-substituted low fat diet. The initial liver biopsy contained 38% lipid, 91% of which was triglyceride. The hepatocytes contained large fat droplets which ruptured to form centrilobular fatty lakes. Ultrastructurally, the Golgi was nearly completely deficient in trans-Golgi vacuole formation. Endogenous triglyceride particles could not be found, and the circum-Golgi smooth endoplasmic reticulum was absent. When the infant was fed a medium chain triglyceride diet, steatorrhea improved and the liver cell cytoplasmic fat droplets became smaller and less numerous. During the 14 months of MCT feedings, however, there was progression of the initially mild hepatic fibrosis to an advanced micronodular cirrhosis, and alcoholic hyalin appeared in the hepatocytes. It is speculated that the evolution of alcoholic hyalin may be related to the accumulation of 2-carbon fragments derived from MCT in the face of defective hepatic triglyceride secretion. Because of the destructive but asymptomatic lesion in this infant’s liver, liver function should be carefully investigated in all children with abetalipoproteinemia. Diagnostic liver biopsy is indicated if hepatomegaly or chemical signs of liver dysfunction persist, particularly if diet manipulation is contemplated.

Quantitative analysis of electron micrographs was performed on cardiac biopsies obtained before and approximately I h following hypothermic cardiopulmonary bypass at 28°C. During bypass the myocardium was exposed to 5, 20 and 30 min of ischemia. Alterations in mitochondrial structure were seen after only 5 min of myocardial ischemia and consisted of end-to-end fusion of these organelles. In the control biopsies, mitochondrial volume fraction ( V vi ) was 0.25, but after 5 min of aortic occlusion it increased to 0.38; after 20 min it was 0.40 and some mitochondria were mildly swollen. After 30 min, V vi was 0.31 and some giant mitochondria were disrupted. The reduction in V vi at 30 min may have been due to the appearance of a new population of small spherical mitochondria. Function studies were done before and after bypass. Mean maximal left ventricular power after 5, 20 and 30 min of myocardial ischemia at 27°C was decreased to 86, 68 and 59%, respectively, of that observed before bypass. This study shows that disruption of myocardial organelles occurs following 20 to 30 min of hypothermic ischemia, corresponding with the moderate decrease in maximal LVP at 30 min.

Cerebral biopsies were obtained for electron microscopy 48 and 72 hours after the onset of encephalopathy from a child with severe Reye's syndrome. Gravely ill at the time of craniectomy to relieve cerebral hypertension, the child survived and recovered good brain function; therefore, the biopsy findings appear to reflect the organelle pathology of the brain at a severe yet reversible stage in the disease process. The cardinal ultrastructural changes in the brain in Reye's syndrome are astrocyte swelling and partial deglycogenation, myelin bleb formation and universal injury of neuron mitochondria. The mitochondrial injury consists of matrix disruption with moderate but not massive swelling. Dilatation of rough endoplasmic reticulum and nuclear changes occurred only in neurons with severely altered mitochondria. The organelle pathology of the brain in this case did not resemble the organelle pathology of the brain in human "hepatic encephalopathy" or in experimental ammonia intoxication in primates. The mitochondrial ultrastructure of the cerebral neurons resembled the unique mitochondrial ultrastructural changes seen in the liver parenchyma in Reye's syndrome.

The hepatic lesion in Reye's syndrome (acute encephalopathy with fatty degeneration of viscera) was studied by light microscopy of sequential biopsy specimens obtained in 49 children. The hepatic lesion is a morphologically characteristic, rapidly evolving, and reversible toxic hepatitis. In specimens obtained with 48 hr of onset of neurological deterioration, the severity of the diffuse microvesicular steatosis is best appreciated in frozen sections stained for lipid content. Variation in severity of hepatocyte glycogen depletion in early biopsies correlates with other histological measures of severity, and with the occurrence of hypoglycemia, severity of the encephalopathy at the time of admission, and mortality rate. Histochemical studies suggest that the hepatic lesion is attributable to mitochondrial injury and other evidence that supports this hypothesis is briefly reviewed. The etiology of the syndrome and its relationship to the viral disease which usually precedes it are unknown.

Serum salicylate concentration was measured at admission in 130 children with liver-biopsy-confirmed Reye's disease. Mean serum salicylate was 12.3 mg/dl and mean salicylate concentrations by neurological grade (Lovejoy) were: stage I, 12, stage II, 13, stage III, 11, stage IV, 13, and stage V, 13 mg/dl. However, mean serum salicylate (15 mg/dl) at admission in 21 patients who died or had serious neurological deficits was significantly higher than that in 103 patients who survived without neurological sequelae (10 mg/dl). Serum salicylate in a group of 27 age-matched, community-matched control children collected consecutively over the period 1978-80 was less than 2 mg/dl, and children with varicella or influenza had salicylate concentrations indistinguishable from apparently well classmates or siblings. It is impossible to determine from this data whether salicylates are involved in the aetiology of or in determining the outcome of Reye's disease. Increased concentrations of salicylates at admission could be the result of excessive dosage because of a greater severity of the prodromal illness, or to diminished excretion because of impaired hepatic metabolism. It seems likely that serum salicylate concentrations entered the toxic range in many patients with Reye's disease before they presented for treatment. Most had been vomiting and had diminished oral intake for 33-55 h before hospital admission. Since the average number of hours from the beginning of vomiting to admission was no different in non-comatose and comatose cases, the time at which salicylate concentration was measured in relation to the last dose was probably similar in the two groups and therefore does not account for the higher levels in children with poor outcome. Salicylates are mitochondrial toxins and mitochondria are known to be significantly injured in Reye's disease; therefore, it seems wise to avoid the use of aspirin in children during outbreaks of Reye's disease.

Plasma renin activity (PRA) is characteristically lower in the Dahl salt-sensitive (S) rat than in the salt-resistant (R) rat. To establish whether PRA differs between these strains at birth or subsequently becomes suppressed in the Dahl S rat, the ontogeny of PRA was studied in inbred Dahl hypertension-prone (S/JR) and hypertension-resistant (R/JR) rats from 5 to 51 days of age. Pregnant dams and postweaning pups were maintained on diets containing either 0.15% or 0.69% sodium chloride (w:w). Although PRA clearly distinguished the two strains in young adulthood, it was not lower in the S/JR pups at 5 and 15 days of age. However, PRA was greater in rat pups suckling dams consuming the low salt diet. These results suggest that suppressed PRA in S/JR rats is an acquired trait, perhaps occurring secondary to other physiological abnormalities and that maternal diet influences PRA in the suckling Dahl rat.

Cyclosporine-induced nephrotoxicity (CIN) was studied in rats treated for 7 days with cyclosporine (10 mg x kg-1 x day-1 im) or vehicle (CON). CIN rats displayed characteristic reductions in glomerular filtration (GFR) and renal blood blood flow (RBF), and electron microscopy showed injury to proximal cells. Metabolic studies (7 day) showed significantly lower renal sodium excretion in conscious CIN rats compared with CON. In anesthetized rats at similar blood pressures, nephron GFR (SNGFR) was lower in CIN than CON, but fractional Na reabsorption was similar. In CIN, SNGFR, measured proximally to block flow to the sensing site of tubuloglomerular feedback (TGF) at the macula densa, was not significantly different than distal SNGFR. The rate of distal fluid delivery was significantly lower in CIN than in CON. Inhibition of the renin-angiotensin system (RAS) with captopril (CAP, 10 mg/kg iv), or saralasin (SAR, 0.3 mg x kg-1 x h-1 iv) caused marked arterial hypotension in CIN and a fall in renal vascular resistance (RVR). With arterial pressure controlled, CAP or SAR increased GFR and RBF, and reduced RVR in CIN, but did not reverse the renal deficits compared with similarly treated CON. RBF autoregulation in CIN was impaired between 90 and 140 mmHg but was partially restored by CAP. We conclude that both the filtered load and excretion rate of sodium in CIN are significantly reduced compared with controls, that SNGFR in CIN is not depressed by TGF in response to elevated distal fluid delivery, and that the RAS is not a primarily mediator of the renal vasoconstriction in CIN.

Acute and recovery biopsies of three patients with Reye's Disease are described. Pleomorphic changes of neuronal mitochondria were identified in all of the acute biopsies, similar in appearance to the characteristic alterations of hepatic mitochondria. Distinctive myelin bleb formation may be directly attributable to the mitochondrial injury. The mitochondrial lesion is reversible. There is morphologic evidence for regeneration and repair of myelin; but the presence of myelin ovoids at long intervals after recovery indicates a loss of some myelinated fibers. The neuronal mitochondrial changes, pleomorphism with matrix expansion, and myelin bleb formation, reflect a specific biochemical injury be attributable to ischemic injury secondary to brain edema.

Inflammatory pseudotumor (IPT) of the liver and intrahepatic bile ducts is a rare cause of obstructive jaundice and portal hypertension in the pediatric age group. Because it seems to have a better long-term outcome than many of the conditions with which it may be confused, it is important to recognize the radiologic and pathologic features of this rare lesion so that appropriate therapy may be instituted.

Quantitative analysis was made of electron micrographs from the hearts of 12 dogs undergoing cardiopulmonary bypass on the Clark heart-lung machine, for 5, 20 and 30 minutes of total aortic occlusion with mild hypothermia (27 C). Mitochondrial changes similar to those found in animals made deficient in components of the electron transport chain occurred as early as 5 minutes. In the control dog hearts, mitochondrial volume fraction (Vvi) was 0.25 ± 0.01, but after 5 minutes of aortic occlusion, there was a striking increase in Vvi to 0.38 ± 0.03. This 52 % increase in volume appears to be due to orderly end-to-end fusion of adjacent mitochondria. Aortic occlusion longer than 5 minutes resulted in progressive specific mitochondrial changes; in addition, there was disruption of the tubular systems of the cell.