ULTRASTRUCTURAL CHANGES OF THE PANCREAS AND LIVER IN CYSTIC FIBROSIS

The Potential Causes of Cystic Fibrosis-Related Diabetes

Cystic fibrosis (CF) is a genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Cystic fibrosis-related diabetes (CFRD) is the most common comorbidity, affecting more than 50% of adult CF patients. Despite this high prevalence, the etiology of CFRD remains incompletely understood. Studies in young CF children show pancreatic islet disorganization, abnormal glucose tolerance, and delayed first-phase insulin secretion suggesting that islet dysfunction is an early feature of CF. Since insulin-producing pancreatic β-cells express very low levels of CFTR, CFRD likely results from β-cell extrinsic factors. In the vicinity of β-cells, CFTR is expressed in both the exocrine pancreas and the immune system. In the exocrine pancreas, CFTR mutations lead to the obstruction of the pancreatic ductal canal, inflammation, and immune cell infiltration, ultimately causing the destruction of the exocrine pancreas and remodeling of islets. Both inflammation and ductal cells have a direct effect on insulin secretion and could participate in CFRD development. CFTR mutations are also associated with inflammatory responses and excessive cytokine production by various immune cells, which infiltrate the pancreas and exert a negative impact on insulin secretion, causing dysregulation of glucose homeostasis in CF adults. In addition, the function of macrophages in shaping pancreatic islet development may be impaired by CFTR mutations, further contributing to the pancreatic islet structural defects as well as impaired first-phase insulin secretion observed in very young children. This review discusses the different factors that may contribute to CFRD.

Phenotypic Characterization and Comparison of Cystic Fibrosis Rat Models Generated Using CRISPR/Cas9 Gene Editing

Animal models of cystic fibrosis (CF) are essential for investigating disease mechanisms and trialing potential therapeutics. This study generated two CF rat models using clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeats-associated protein 9 gene editing. One rat model carries the common human Phe508del (ΔF508) CF transmembrane conductance regulator (CFTR) mutation, whereas the second is a CFTR knockout model. Phenotype was characterized using a range of functional and histologic assessments, including nasal potential difference to measure electrophysiological function in the upper airways, RNAscope in situ hybridization and quantitative PCR to assess CFTR mRNA expression in the lungs, immunohistochemistry to localize CFTR protein in the airways, and histopathologic assessments in a range of tissues. Both rat models revealed a range of CF manifestations, including reduced survival, intestinal obstruction, bioelectric defects in the nasal epithelium, histopathologic changes in the trachea, large intestine, and pancreas, and abnormalities in the development of the male reproductive tract. The CF rat models presented herein will prove useful for longitudinal assessments of pathophysiology and therapeutics.

Cystic fibrosis-related diabetes is caused by islet loss and inflammation

Cystic fibrosis-related (CF-related) diabetes (CFRD) is an increasingly common and devastating comorbidity of CF, affecting approximately 35% of adults with CF. However, the underlying causes of CFRD are unclear. Here, we examined cystic fibrosis transmembrane conductance regulator (CFTR) islet expression and whether the CFTR participates in islet endocrine cell function using murine models of β cell CFTR deletion and normal and CF human pancreas and islets. Specific deletion of CFTR from murine β cells did not affect β cell function. In human islets, CFTR mRNA was minimally expressed, and CFTR protein and electrical activity were not detected. Isolated CF/CFRD islets demonstrated appropriate insulin and glucagon secretion, with few changes in key islet-regulatory transcripts. Furthermore, approximately 65% of β cell area was lost in CF donors, compounded by pancreatic remodeling and immune infiltration of the islet. These results indicate that CFRD is caused by β cell loss and intraislet inflammation in the setting of a complex pleiotropic disease and not by intrinsic islet dysfunction from CFTR mutation.

Glycaemic regulation and insulin secretion are abnormal in cystic fibrosis pigs despite sparing of islet cell mass

Diabetes is a common and significant co-morbidity in cystic fibrosis (CF). The pathogenesis of cystic fibrosis related diabetes (CFRD) is incompletely understood. Because exocrine pancreatic disease is similar between humans and pigs with CF, the CF pig model has the potential to contribute significantly to the understanding of CFRD pathogenesis. We determined the structure of the endocrine pancreas in fetal, newborn and older CF and non-CF pigs and assessed endocrine pancreas function by intravenous glucose tolerance test (IV-GTT). In fetal pigs, pancreatic insulin and glucagon density was similar between CF and non-CF. In newborn and older pigs, the insulin and glucagon density was unchanged between CF and non-CF per total pancreatic area, but increased per remnant lobular tissue in CF reflecting exocrine pancreatic loss. Although fasting glucose levels were not different between CF and non-CF newborns, CF newborns demonstrated impaired glucose tolerance and increased glucose area under the curve during IV-GTT. Second phase insulin secretion responsiveness was impaired in CF newborn pigs and significantly lower than that observed in non-CF newborns. Older CF pigs had elevated random blood glucose levels compared with non-CF. In summary, glycaemic abnormalities and insulin secretion defects were present in newborn CF pigs and spontaneous hyperglycaemia developed over time. Functional changes in CF pig pancreas were not associated with a decline in islet cell mass. Our results suggest that functional islet abnormalities, independent of structural islet loss, contribute to the early pathogenesis of CFRD.

Pancreatic and biliary secretion are both altered in cystic fibrosis pigs

The pancreas, liver, and gallbladder are commonly involved in cystic fibrosis (CF), and acidic, dehydrated, and protein-rich secretions are characteristic findings. Pancreatic function studies in humans have been done by sampling the jejunal fluid. However, it has been difficult to separately study the function of pancreatic and biliary systems in humans with CF, because jejunal fluid contains a mixture of bile and pancreatic fluids. In contrast, pancreatic and biliary ducts open separately into the porcine intestine; therefore, biliary and pancreatic fluid can be individually analyzed in CF pigs. We studied newborn wild-type (WT) and CF pigs and found that CFTR was localized to the pancreatic ducts. We collected bile and pancreatic fluid and analyzed pancreatic enzymes with activity assays and immunoblot. Pancreatic enzyme expression was significantly decreased in CF compared with WT pigs. The volume and pH of pancreatic fluid were significantly lower and protein concentration was >5-fold higher in CF pigs. Secretin stimulation increased pancreatic fluid volume and pH in WT, but not CF, pigs. Baseline bile volume did not differ between WT and CF pigs, but volume did not increase in response to secretin in CF pigs. Bile pH was lower and protein concentration was twofold higher in CF pigs. These results indicate that pancreatic and biliary secretions are altered in CF pigs. Abnormal pancreatic and biliary secretion in CF may have important implications in disease pathogenesis.

Pancreatic damage in fetal and newborn cystic fibrosis pigs involves the activation of inflammatory and remodeling pathways

Pancreatic disease has onset in utero in humans with cystic fibrosis (CF), and progresses over time to complete destruction of the organ. The exact mechanisms leading to pancreatic damage in CF are incompletely understood. Inflammatory cells are present in the pancreas of newborn pigs with CF (CF pigs) and humans, which suggests that inflammation may have a role in the destructive process. We wondered whether tissue inflammation and genes associated with inflammatory pathways were increased in the pancreas of fetal CF pigs [83 to 90 days gestation (normal pig gestation is ~114 days)] and newborn pigs. Compared with fetal pigs without CF (non-CF pigs), in fetal CF pigs, the pancreas exhibited patchy inflammation and acinar atrophy, with progression in distribution and severity in neonatal CF pigs. Large-scale transcript profiling revealed that the pancreas in fetal and newborn CF pigs exhibited significantly increased expression of proinflammatory, complement cascade, and profibrotic genes when compared with fetal and newborn non-CF pigs. Acinar cells exhibited increased apoptosis in the pancreas of fetal and newborn CF pigs. α-Smooth muscle actin and transforming growth factor β1 were increased in both fetal and newborn CF pig pancreas, suggesting activation of profibrotic pathways. Cell proliferation and mucous cell metaplasia were detected in newborn, but not fetal, CF pigs, indicating that they were not an initiator of pathogenesis but a response. Proinflammatory, complement cascade, proapoptotic, and profibrotic pathways are activated in CF pig pancreas, and likely contribute to the destructive process.

PB, Butler J, Uc A. An activated immune and inflammatory response targets the pancreas of newborn pigs with cystic fibrosis

BACKGROUND/AIMS

In cystic fibrosis (CF), pancreatic disease begins in utero and progresses over time to complete destruction of the organ. Although inflammatory cells have been detected in the pancreas of humans and pigs with CF, their subtypes have not been characterized.

METHODS

Using four-color flow cytometry, we analyzed the surface antigens of leukocytes in pancreas, blood, and mesenteric lymph nodes (MLN) of newborn pigs with CF (CFTR(-/-) and CFTR(Δ)(F508/)(Δ)(F508)) and in those without CF (CFTR(+/-), CFTR(+/)(Δ)(F508), CFTR(+/+)). Pancreatic histopathology was examined with HE stain.

RESULTS

CF pig pancreas had patchy distribution of inflammatory cells with neutrophils/macrophages in dilated acini, and lymphocytes in the interstitium compared to non-CF. B cells, effector (MHC-II(+)) and cytotoxic (CD2(+)CD8(+)) γδ T cells, activated (MHC-II(+) and/or CD25(+)) and effector (CD4(+)CD8(+)) αβ T helper cells, effector natural killer cells (MHC-II(+)CD3(-)CD8(+)), and monocytes/macrophages and neutrophils were increased in the CF pig pancreas compared to pigs without CF. Blood and MLN leukocyte populations were not different between CF and non-CF pigs.

CONCLUSIONS

We discovered an activated immune response that was specific to the pancreas of newborn CF pigs; inflammation was not systemic. The presence of both innate and adaptive immune cells suggests that the disease process is complex and extensive.

Pathology of gastrointestinal organs in a porcine model of cystic fibrosis

Cystic fibrosis (CF), which is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), is characterized by multiorgan pathology that begins early in life. To better understand the initial stages of disease, we studied the gastrointestinal pathology of CFTR-/- pigs. By studying newborns, we avoided secondary changes attributable to environmental interactions, infection, or disease progression. Lesions resembling those in humans with CF were detected in intestine, pancreas, liver, gallbladder, and cystic duct. These organs had four common features. First, disease was accelerated compared with that in humans, which could provide a strategy to discover modifying factors. Second, affected organs showed variable hyperplastic, metaplastic, and connective tissue changes, indicating that remodeling was a dynamic component of fetal life. Third, cellular inflammation was often mild to moderate and not always present, which raises new questions as to the role of cellular inflammation in early disease pathogenesis. Fourth, epithelial mucus-producing cells were often increased, producing a striking accumulation of mucus with a layered appearance and resilient structure. Thus, mucus cell hyperplasia and mucus accumulation play prominent roles in early disease. Our findings also have implications for CF lung disease, and they lay the foundation for a better understanding of CF pathogenesis.

Hepatic failure with neonatal tissue siderosis of hemochromatotic type in an infant presenting with meconium ileus. Case report and differential diagnosis of the perinatal iron storage disorders

We report on a female preterm infant with hepatic failure and neonatal tissue siderosis of hemochromatotic type diagnosed by using both histochemistry and atomic absorption spectroscopy. The infant presented with meconium ileus, signs of rapidly progressive hepatic failure, and hyperferritinemia (7132 ng/ml). Despite surgery and intensive care the infant died 32 days after birth. Postmortem examination showed a wrinkled liver with extensive collapse of the hepatic architecture and regenerating nodules as well as hepatic and extrahepatic iron accumulation of hemochromatotic type, sparing the reticuloendothelial system. Atomic absorption spectroscopy confirmed an increase in the iron content of various organs: liver, heart, pancreas, oral salivary gland, kidney, and adrenal gland. The increase in the iron content of various organs was determined by comparing the analysis of the propositus with those of 5 gestationally age-related preterm infants who had died in the intensive care unit: 2 died of meconium aspiration syndrome, the other 3 of hyaline membrane disease, bronchopulmonary dysplasia, and immaturity, respectively. We also compared the analysis of 15 fetuses having a a condition predisposing to iron accumulation (trisomy 21, trisomy 18, cytomegalovirus, amnion infection syndrome, Rhesus- and ABO-incompatibility, congenital hemolysis, anti-phospholipid syndrome, congenital heart disease). Delta F508, the most frequent mutation seen in cystic fibrosis patients, was excluded by gene sequencing. Different noxae causing iron accumulation in the neonatal period have led to the statement that neonatal hemochromatosis may collect different etiologies, such as metabolic disorders, infections, chromosomal aberrations, and immunological disorders. In this study, we report the singular evidence of neonatal iron accumulation of hemochromatotic type in an infant presenting with meconium ileus and propose a classification of the neonatal disorders associated with iron accumulation.

Hepatobiliary manifestations of cystic fibrosis in children: correlation of CT and US findings

MATERIAL AND METHODS

Abdominal US and CT scans of 50 pediatric cystic fibrosis (CF) patients were evaluated to search for specific data that can be attributed to the involvement of the hepatobiliary system. The liver findings of the two patients who were HBs antigen carriers were excluded from the study.

RESULTS

30 out of 48 patients had at least one abnormal finding of liver on CT and/or US. Although increased echogenicity of the liver was detected in 24 of 48 patients (50%), only six of these (12%) were regarded as steatosis according to CT criteria of low attenuation values. CT and US scans both showed unique multilobular fatty pattern, described as "pseudomasses" in three patients. Increased periportal echogenicity was seen in 18 (37%) patients on US, while CT could not demonstrate any sign of increased periportal thickness. Findings of cirrhosis were present in five patients with either modalities. Lymph nodes of less than 10-15 mm in diameter were detected at the hepatico-duodenal ligament in 18 (37%) patients. Anomalies of the gallbladder (absence or microgallbladder or stone) were detected in 12 cases (24%).

CONCLUSION

Although US is the most widely used modality in CF patients, CT and US correlation will help to better delineate the abnormalities between steatosis and periportal fibrosis and increase the sensitivity of the imaging methods to achieve the most accurate diagnosis.

Imaging changes in the pancreas in cystic fibrosis: a retrospective evaluation of 55 cases seen over a period of 9 years

BACKGROUND

Pathologic changes of the pancreas have been observed as early as the recognition of the disease termed initially "cystic fibrosis of the pancreas". Atrophy of the gland and its fatty infiltration were considered as usual features. The aim of this study was to follow-up the evolution of cystic fibrosis pancreas and to define its successive stages in correlation with the clinical, biochemical, and imaging findings.

METHODS

Fifty-five patients were followed up during 9 years. The patients' genetic backgrounds were systematically performed. Blood lipase levels were analyzed systematically at each consultation of the patients and in the event of bouts of abdominal pains. Imaging using mainly echograms and tomodensitometric scans were regularly performed: echograms every 6 months, and tomodensitometric scans every 1 to 2 years. Magnetic resonance imaging was performed in four patients.

RESULTS

Five groups of patients were identified on the basis of tomodensitometric scan findings: normal pancreas (n = 4), incomplete lipomatosis of the pancreas (n = 9), complete lipomatosis of the pancreas (n = 23), cystic pancreas (n = 5), macrocystic pancreas (n = 1), atrophic pancreas (n = 13). Pancreas exocrine function was not correlated with findings. Forty episodes of pancreatitis were observed in seven patients. They had bouts of abdominal pain and elevation of lipase levels. Five of these patients were composite heterozygotes (D508/other). Incomplete lipomatosis represents an intermediate stage leading toward complete lipomatosis or toward atrophy after pancreatitis.

CONCLUSIONS

Studies of pancreatic function should be performed routinely in cystic fibrosis, especially in pancreatic sufficiency or in patients with normal pancreas images. Acute pancreatitis should be diagnosed and properly identified to be differentiated from other acute abdominal syndromes occurring in cystic fibrosis.

Pancreatic expression of keratinocyte growth factor leads to differentiation of islet hepatocytes and proliferation of duct cells

Keratinocyte growth factor, (KGF), a member of the fibroblast growth factor (FGF) family, is involved in wound healing. It also promotes the differentiation of many epithelial tissues and proliferation of epithelial cells as well as pancreatic duct cells. Additionally, many members of the highly homologous FGF family (including KGF), influence both growth and cellular morphology in the developing embryo. We have previously observed elevated levels of KGF in our interferon-gamma transgenic mouse model of pancreatic regeneration. To understand the role of KGF in pancreatic differentiation, we generated insulin promoter-regulated KGF transgenic mice. Remarkably, we have found that ectopic KGF expression resulted in the emergence of hepatocytes within the islets of Langerhans in the pancreas. Additionally, significant intra-islet duct cell proliferation in the pancreata of transgenic KGF mice was observed. The unexpected appearance of hepatocytes and proliferation of intra-islet duct cells in the pancreata of these mice evidently stemmed directly from local exposure to KGF.

Mutations of the cystic fibrosis gene in patients with chronic pancreatitis

BACKGROUND

The pancreatic lesions of cystic fibrosis develop in utero and closely resemble those of chronic pancreatitis. Therefore, we hypothesized that mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene may be more common than expected among patients with chronic pancreatitis.

METHODS

We studied 134 consecutive patients with chronic pancreatitis (alcohol-related disease in 71, hyperparathyroidism in 2, hypertriglyceridemia in 1, and idiopathic disease in 60). We examined DNA for 22 mutations of the CFTR gene that together account for 95 percent of all mutations in patients with cystic fibrosis in the northwest of England. We also determined the length of the noncoding sequence of thymidines in intron 8, since the shorter the sequence, the lower the proportion of normal CFTR messenger RNA.

RESULTS

The 94 male and 40 female patients ranged in age from 16 to 86 years. None had a mutation on both copies of the CFTR gene. Eighteen patients (13.4 percent), including 12 without alcoholism, had a CFTR mutation on one chromosome, as compared with a frequency of 5.3 percent among 600 local unrelated partners of persons with a family history of cystic fibrosis (P<0.001). A total of 10.4 percent of the patients had the 5T allele in intron 8 (14 of 134), which is twice the expected frequency (P=0.008). Four patients were heterozygous for both a CFTR mutation and the 5T allele. Patients with a CFTR mutation were younger than those with no mutations (P=0.03). None had the combination of sinopulmonary disease, high sweat electrolyte concentrations, and low nasal potential-difference values that are diagnostic of cystic fibrosis.

CONCLUSIONS

Mutations of the CFTR gene and the 5T genotype are associated with chronic pancreatitis.

Differential recruitment of B and T cells in coxsackievirus B4-induced pancreatitis is influenced by a capsid protein

Two genetically similar variants of coxsackievirus B4, CB4-P and CB4-V, cause distinct disease syndromes in mice. A multidisciplinary approach was used to examine the events occurring in situ. The CB4-P variant induced acute pancreatitis, followed by repair of the exocrine tissues, while the CB4-V variant induced chronic pancreatitis, characterized by extensive destruction of the exocrine tissues. Since CB4-V replicated more efficiently than CB4-P in vivo, the more extensive tissue injury associated with CB4-V infection could be explained as the result of a higher level of viral replication. However, the fact that CB4-V replicated more efficiently in a mouse strain that survives infection than in a strain that succumbs to infection suggests that immune-mediated mechanisms as well as viral cytolysis may contribute to pancreatic tissue injury. To address the role of the immune system in virus-induced pancreatitis, the cell types within the inflammatory infiltrate were analyzed by flow cytometry. B cells (34 to 75%) were the most abundant, followed by T cells (10 to 30%), natural killer cells (4 to 8%), and macrophages (0 to 6%). Recruitment (and perhaps proliferation) of B and T cells to the pancreatic tissues was influenced by viral strain. Differential recruitment of T and B cells may reflect altered antigenic sites between CB4-P and CB4-V. The viral sequence that affected T- and B-cell recruitment was identified as a threonine residue at position 129 of the VP1 capsid protein.

Liver cirrhosis in cystic fibrosis--therapeutic implications and long term follow up

Experience gained from liver studies in 450 patients with cystic fibrosis, seen in a 38 year period from 1964 to 1992, is surveyed. Of these, 31 (7%) showed findings that indicated multilobular cirrhosis. There was a slight but not significant male predominance: 19 males against 12 females. Liver disease had its onset during childhood in most cases. The natural course of liver disease and of cirrhosis is protracted. All patients were routinely evaluated by way of: (i) clinical examination, (ii) biochemical studies and specifically estimation of transaminases and gamma glutamyltransferase, and (iii) liver imaging, ultrasonography, and computed tomography. The study aimed to detect early liver disease, that is multilobular cirrhosis and its complications, with a view to optimal introduction of treatment with ursodeoxycholic acid as this drug shows promise for preventing or stabilising the cirrhotic process. Effects of surgical treatment on portal hypertension are surveyed. These include portacaval shunting, partial splenectomy (considered the procedure of choice), liver transplant in the event of liver failure, or a triple transplant (liver, lungs, and heart) if necessary. One triple transplant was successfully performed in a boy of 10 years with a 2 year follow up.

Histochemical and immunocytochemical characterizations of laminated bodies in the pancreas acinar lumen

Combined adrenalectomy and castration cause numerous morphological alterations in the exocrine pancreas of the rat. Accumulation of laminated bodies (LB) in the acinar lumen is one of these alterations. A series of classical histological stains was applied to identify the components of these structures. A positive reaction was observed with periodic acid-Schiff, Congo red, and Alcian blue (pH 2.5). The first stain reacts with neutral and some acid mucosubstances and the second with amyloid, whereas the last one reacts with sulfated and nonsulfated acid mucosubstances. The LB also responded to Luxol fast blue, indicating the presence of lipids, an observation that is in agreement with the osmiophilic properties of these structures. A more specific identification of LB components was carried out with the immunocytochemical protein A-gold technique. Presence of gamma-glutamyltranspeptidase (gamma-GT) and GP2, two glycoproteins known to be secreted by the pancreas, was tested. The gamma-GT was associated with LB whereas GP2 was found in the lumen but not associated with these structures. Amylase was undetectable when LB occupied the lumen, suggesting that the process leading to production of LB also blocks secretory activity. To determine if diet influences LB accumulation in the pancreas acinar lumen, their frequency was compared in rats fed Purina Lab Chow or a lipid-free synthetic diet. A significant increase was observed in castrated-adrenalectomized rats fed the latter diet. This increase corresponded to a pronounced reduction in the number of zymogen granules (ZG) in the acinar cell. Our results show that LB are made of lipids, neutral mucosubstances, and nonsulfated acid mucosubstances, and that hormonal (steroids) and dietary factors (lipids) influence their accumulation.

Sclerosing cholangitis with hepatic microvesicular steatosis in cystic fibrosis and chronic pancreatitis

The association between asymptomatic primary sclerosing cholangitis and exocrine pancreatic disease was underlined by the findings in a patient with cystic fibrosis and in another with chronic pancreatitis. In each case hepatocytes showed extensive microvesicular steatosis and studies of drug metabolism suggested hepatic enzyme induction: biliary or serum analysis, or both, disclosed raised concentrations of a lipid-based marker of free radical oxidation. These findings suggest that toxic metabolites of oxygen or other chemicals may have a role in the pathogenesis of the bile duct lesion.

Aberrant free radical activity in cystic fibrosis

It has been suggested that the molar ratio of octadeca 9,11 dienoic acid to linoleic acid in biological material provides an index of activity along the non-peroxide pathway of a free radical attack on polyunsaturated fatty acids. In 17 adults with cystic fibrosis the 'molar ratio' in nasal epithelial cells--a recognised target of the disease--exceeded that in 20 controls (median 2.09%, range 1.70-3.01% versus 1.56, 0.92-2.23%, p = 0.0002). The difference was also apparent, although less stark, upon analysis of serum in a further 22 CF patients (2.48%, 1.60-5.24%) and 25 controls (1.96%, 0.81-3.90%, p = 0.0348). There was no correlation between the 'molar ratio' and blood white cell count or erythrocyte sedimentation rate, severity of lung or liver disease, indicating that the raised values are a primary feature, rather than reflecting disease severity. Aberrant free radical activity may underlie cellular dysfunction in cystic fibrosis.

The hypervitaminosis-A rat: a model for mucin hypersecretion in cystic fibrosis?

Cystic fibrosis is a devastating disease with pathognomonic features typically displayed in the exocrine system. An obvious drawback with human clinical studies of the disease is the relative inaccessibility of its "target-tissues," i.e., the salivary glands, intestine, pancreas, and tracheobronchial tree. Thus, little is known about its underlying cellular mechanisms. For this reason, physiologically relevant animal models for the disease are vitally needed. At present, there are animal models available for certain salivary gland biochemical aspects of the disease and for bicarbonate ion secretory alterations. However, no adequate model exists for excessive mucus production, an aspect of the disease which sets the stage for life-threatening infections and digestive disorders. This manuscript examines morphological and biochemical changes occurring in various biological systems exposed to high levels of vitamin A and correlates such changes with abnormalities commonly seen in cystic fibrosis.

Histochemical and ultrastructural characteristics of tubular complexes in human acute pancreatitis

The morphologic characteristics of ductlike tubular complexes were studied in human acute pancreatitis. Pancreatic specimens were obtained from 10 patients who were operated on for acute pancreatitis. Immunocytochemistry for pancreatic enzymes, keratin, actin, and carcinoembryonic antigen were combined with lectin-binding studies and ultrastructural investigations. Irrespective of clinical onset and duration of pancreatitis, tubular complexes situated in the vicinity of fat necrosis were observed in all patients. Intermediate forms of ductlike structures were characterized by widening of acinar lumina, decreased height of acinar cells, and large autophagic vacuoles. These structures bound all of the lectins employed and retained their immunoreactivity to secretory proteins. Typical tubular complexes were composed of low cuboidal or flattened cells surrounding a large acinar lumen. They revealed a loss for pancreatic enzymes, a reduced lectin-binding for L-fucose and N-acetylgalactosamine, and an increase for cytoskeletal proteins (keratin, actin). It is concluded that tubular complexes in human acute pancreatitis represent degenerating acinar cells which lost their secretory and membrane characteristics.

Salivary gland changes in disease

Ultrastructural alterations occurring in human salivary glands as a result of a variety of diseases are described. Major changes in these organs in cases of cystic fibrosis are probably the result of duct blockage, as indicated by study of chronically inflamed salivary glands. A new disease of salivary glands is reported in which parotid serous granules are distorted by bundles of fine filaments, which may be due to the untoward polymerization of a secretory protein, perhaps proline-rich protein. Finally, a clear-cell adenocarcinoma of palatine gland origin is described in which the nuclei display complex pseudoinclusions and the cytoplasm contains numerous herpes-type viruses.

Morphological findings in the liver of children with cystic fibrosis: a light and electron microscopical study

Liver tissue from five children with cystic fibrosis, obtained through percutaneous liver biopsies, have been investigated via light and electron microscopy. None of the patients had clinical evidence of liver disorder, and their blood chemistry was mainly normal. Light microscopy showed slight fibrosis in three cases, more advanced fibrosis in one case and focal cirrhotic changes in one case. All patients had fatty infiltration in the hepatocytes and glycogen in the nuclei of these cells. Electron microscopy showed an increase in the number of Ito cells around the portal tracts and also fibrosis in all patients. In the majority of hepatocytes, no evident necrosis was seen. Hypertrophy of the smooth endoplasmic reticulum and the Golgi apparatus were noted. Large lysosomes containing lipofuscin and lipids were also present. No direct evidence of cholestasis could be seen in the hepatocytes. The bile canaliculi were not dilated and did not contain bile plugs. No bile pigment was seen in the cells, and direct evidence of cholestasis was thus not found in the hepatocytes. Other organelles, such as the rough endoplasmic reticulum, peroxisomes and mitochondria, had a normal appearance. Bile ducts, even when seen in fibrotic portal tracts, were not dilated. The ultrastructural findings cannot explain the basis for the liver cell damage. Cholestasis does not seem to be a presumable etiological factor as judged from the findings in the present study.

Cystic fibrosis: a casualty of "detoxification"?

It is proposed that excessive and/or aberrant function of cytochromes P450, due to a combination of genetic and environmental influences, is the basic defect in cystic fibrosis. Organs that are involved in oxidative detoxification reactions in foetal life are thus at risk: tissue damage is initiated by excessive production of oxygen free radicals which deplete cellular antioxidants and provoke the secretion of mucus.

Probe of the (Ca2+ + Mg2+)-ATPase in erythrocyte membranes of cystic fibrosis patients

There are several conflicting reports regarding a defective (Ca2+ + Mg2+)-ATPase in tissues from cystic fibrosis (CF) patients. The work presented in this paper represents an independent assessment of (Ca2+ + Mg2+)-ATPase function in CF and, at the same time, provides a somewhat more detailed analysis of the enzyme from CF patients than has previously existed. We found no significant differences in either the Km value for Ca2+ or the Vm value of the (Ca2+ + Mg2+)-ATPase in membrane preparations from CF patients and control subjects when the red cell membranes were prepared by methods which utilize Tris-glycylglycine-Mg2+ buffers. In contrast, the Vm value of the (Ca2+ + Mg2+)-ATPase in the preparations from CF patients was found to be lower than that from control subjects when the membranes were prepared by a series of washes with EDTA-containing buffers (i.e., 1-10 mmol/1 EDTA). The EDTA treatment, however, did not produce any significant difference in the Km between the two groups. The fluorescent ATP analogue, trinitrocyclohexadienylidine-ATP, appeared to interact with erythrocyte ghosts as evidenced from an enhancement of its fluorescence. This enhancement was greater in control preparations than in samples from CF patients. In addition, the kinetic profiles, with respect to ATP, were quite different between the two enzyme populations. The overall results suggest that the lower rate of ATP hydrolysis observed with membranes from CF patients may reflect an impaired utilization of the substrate by the (Ca2+ + Mg2+)-ATPase from these individuals.

Pancreatic structure and function in the immature reserpinized rat

Immature rats were reserpinized to determine whether the model used for adults may be suitable for the study of pancreatic exocrine insufficiency seen in infants with cystic fibrosis. Rats were reserpinized by injections either into pregnant dams or into newborn rats. The dose of reserpine used by others was lethal to immature rats, so lower doses were used. Pancreas from 1-day-old fetal-treated pups was hypoplastic, but concentration of chymotrypsinogen was elevated. At age 7 days hyperplasia was seen. When rats were reserpinized as neonates, hypoplasia and decrease in all parameters measured was observed at age 7 days. Progressive recovery occurred during the following 2 weeks in both groups. Electron microscopic study of the fetal-treated 24-hr-old pancreas revealed evidence of acinar cell degeneration with the presence of abnormal zymogen granules. At age 7 days the pancreas from neonatal-treated rat pups appeared to have a reduced number of granules. At ages 14 and 21 days the pancreas was similar to that seen at age 7 days except that the granules were larger and some acinar lumina were filled with a finely granular, homogeneously dense material. It is concluded that prenatal and neonatal reserpinization of rats induces changes in pancreas similar to those found in cystic fibrosis.