Duodenal Diverticular Bleeding Treated with Endoscopy or Transcatheter Arterial Embolization: A Report of Two Cases and a Literature Review

Duodenal diverticular bleeding (DDB) is extremely rare. We herein report 2 life-threatening cases of DDB successfully treated with endoscopy or transcatheter arterial embolization (TAE) and review 13 cases of DDB reported from Japan. When upper gastrointestinal bleeding of unknown origin is encountered in middle-aged or older adults, DDB should be included in the differential diagnosis. DDB often causes massive bleeding. It is therefore important to judge which is safer and more effective, endoscopy or TAE, based on the general condition of the patient. In addition, it is critical to attempt hemostasis via various strategies, including different gastroscopes and hemostatic devices.

Analysis of distribution, collection, and confirmation of capacity dependency of small extracellular vesicles toward a therapy for liver cirrhosis

BACKGROUND

The progression of liver fibrosis leads to portal hypertension and liver dysfunction. However, no antifibrotic agents have been approved for cirrhosis to date, making them an unmet medical need. Small extracellular vesicles (sEVs) of mesenchymal stem cells (MSCs) are among these candidate agents. In this study, we investigated the effects of sEVs of MSCs, analyzed their distribution in the liver post-administration, whether their effect was dose-dependent, and whether it was possible to collect a large number of sEVs.

METHODS

sEVs expressing tdTomato were generated, and their uptake into constituent liver cells was observed in vitro, as well as their sites of uptake and cells in the liver using a mouse model of liver cirrhosis. The efficiency of sEV collection using tangential flow filtration (TFF) and changes in the therapeutic effects of sEVs in a volume-dependent manner were examined.

RESULTS

The sEVs of MSCs accumulated mostly in macrophages in damaged areas of the liver. In addition, the therapeutic effect of sEVs was not necessarily dose-dependent, and it reached a plateau when the dosage exceeded a certain level. Furthermore, although ultracentrifugation was commonly used to collect sEVs for research purposes, we verified that TFF could be used for efficient sEV collection and that their effectiveness is not reduced.

CONCLUSION

In this study, we identified some unknown aspects regarding the dynamics, collection, and capacity dependence of sEVs. Our results provide important fundamentals for the development of therapies using sEVs and hold potential implications for the therapeutic applications of sEV-based therapies for liver cirrhosis.

Escherichia coli-derived outer-membrane vesicles induce immune activation and progression of cirrhosis in mice and humans

BACKGROUND AND AIMS

Decompensated cirrhosis with fibrosis progression causes portal hypertension followed by an oedematous intestinal tract. These conditions weaken the barrier function against bacteria in the intestinal tract, a condition called leaky gut, resulting in invasion by bacteria and bacterial components. Here, we investigated the role of outer-membrane vesicles (OMVs) of Escherichia coli, which is the representative pathogenic gut-derived bacteria in patients with cirrhosis in the pathogenesis of cirrhosis.

METHODS

We investigated the involvement of OMVs in humans using human serum and ascites samples and also investigated the involvement of OMVs from E. coli in mice using mouse liver-derived cells and a mouse cirrhosis model.

RESULTS

In vitro, OMVs induced inflammatory responses to macrophages and neutrophils, including the upregulation of C-type lectin domain family 4 member E (Clec4e), and induced the suppression of albumin production in hepatocytes but had a relatively little direct effect on hepatic stellate cells. In a mouse cirrhosis model, administration of OMVs led to increased liver inflammation, especially affecting the activation of macrophages, worsening fibrosis and decreasing albumin production. Albumin administration weakened these inflammatory changes. In addition, multiple antibodies against bacterial components were increased with a progressing Child-Pugh grade, and OMVs were detected in ascites of patients with decompensated cirrhosis.

CONCLUSIONS

In conclusion, OMVs induce inflammation, fibrosis and suppression of albumin production, affecting the pathogenesis of cirrhosis. We believe that our study paves the way for the future prevention and treatment of cirrhosis.

Synthesized HMGB1 peptide prevents the progression of inflammation, steatosis, fibrosis, and tumor occurrence in a non-alcoholic steatohepatitis mouse model

AIM

Non-alcoholic steatohepatitis (NASH) with fibrosis eventually leads to cirrhosis and hepatocellular carcinoma. Thus, the development of therapies other than dietary restriction and exercise, particularly those that suppress steatosis and fibrosis of the liver and have a long-term beneficial effect, is necessary. We aimed to evaluate the therapeutic effects of the HMGB1 peptide synthesized from box A using the melanocortin-4 receptor-deficient (Mc4r-KO) NASH model mouse.

METHODS

We performed short- and long-term administration of this peptide and evaluated the effects on steatosis, fibrosis, and carcinogenesis using Mc4r-KO mice. We also analyzed the direct effect of this peptide on macrophages and hepatic stellate cells in vitro and performed lipidomics and metabolomics techniques to evaluate the effect.

RESULTS

Although this peptide did not show direct effects on macrophages and hepatic stellate cells in vitro, in the short-term administration model, we could confirm the reduction of liver damage, steatosis, and fibrosis progression. The results of lipidomics and metabolomics suggested that the peptide might ameliorate NASH by promoting lipolysis via the activation of fatty acid β-oxidation and improving insulin resistance. In the long-term administration model, this peptide prevented progression to cirrhosis but retained the steatosis state, that is, the peptide prevents the progression to "burnt-out NASH." This peptide inhibited carcinogenesis by about one-third.

CONCLUSION

This HMGB1 peptide can reduce liver damage, improve fibrosis and steatosis, and inhibit carcinogenesis, suggesting that the peptide would be a new treatment candidate for NASH and can contribute to the long-term prognosis for patients with NASH.

Small extracellular vesicles and liver diseases: From diagnosis to therapy

Extracellular vesicles (EVs), especially small EVs (sEVs) derived from liver cells, have been the focus of much attention in the normal physiology and pathogenesis of various diseases affecting the liver. sEVs are approximately 100 nm in size, enclosed within lipid bilayers, and are very stable. The lipids, proteins, and nucleic acids, including miRNAs, contained within these vesicles are known to play important roles in intercellular communication. This mini-review summarizes the application of sEVs. First, liver diseases and the related diagnostic markers are described, and the current active status of miRNA research in diagnosis of hepatocellular carcinoma (HCC) is reported. Second, the biodistribution and pharmacokinetics of sEVs are described, and the liver is highlighted as the organ with the highest accumulation of sEVs. Third, the relationship between sEVs and the pathogenesis of liver disorders is described with emphesis on the current active status of miRNA research in HCC recurrence and survival. Finally, the possibility of future therapy using sEVs from mesenchymal stem (stromal) cells for cirrhosis and other diseases is described.

A novel prostaglandin I2 agonist, ONO-1301, attenuates liver inflammation and suppresses fibrosis in non-alcoholic steatohepatitis model mice

BACKGROUND

ONO-1301 is a novel long-lasting prostaglandin (PG) I₂ mimetic with inhibitory activity on thromboxane (TX) A₂ synthase. This drug can also induce endogenous prostaglandin (PG)I2 and PGE2 levels. Furthermore, ONO-1301 acts as a cytokine inducer and can initiate tissue repair in a variety of diseases, such as pulmonary hypertension, pulmonary fibrosis, cardiac infarction, and obstructive nephropathy. In this study, our aim was to evaluate the effect of ONO-1301 on liver inflammation and fibrosis in a mouse model of non-alcoholic steatohepatitis (NASH).

METHODS

The therapeutic effects of ONO-1301 against liver damage, fibrosis, and occurrence of liver tumors were evaluated using melanocortin 4 receptor-deficient (Mc4r-KO) NASH model mice. The effects of ONO-1301 against macrophages, hepatic stellate cells, and endothelial cells were also evaluated in vitro.

RESULTS

ONO-1301 ameliorated liver damage and fibrosis progression, was effective regardless of NASH status, and suppressed the occurrence of liver tumors in Mc4r-KO NASH model mice. In the in vitro study, ONO-1301 suppressed LPS-induced inflammatory responses in cultured macrophages, suppressed hepatic stellate cell (HSC) activation, upregulated vascular endothelial growth factor (VEGF) expression in HSCs, and upregulated hepatocyte growth factor (HGF) and VEGF expression in endothelial cells.

CONCLUSIONS

The results of our study highlight the potential of ONO-1301 to reverse the progression and prevent the occurrence of liver tumors in NASH using in vivo and in vitro models. ONO-1301 is a multidirectional drug that can play a key role in various pathways and can be further analyzed for use as a new drug candidate against NASH.

Novel Strategy for Diagnosis of Focal Nodular Hyperplasia Using Gadolinium Ethoxybenzyl Diethylenetriaminepentaacetic Acid: Enhanced Magnetic Resonance Imaging and Magnetic Resonance Elastography

Focal nodular hyperplasia (FNH) is the second most frequent benign liver tumor, and it is a fiber-rich stiff lesion. Typically, FNH can be diagnosed by imaging without biopsy. However, liver biopsy and diagnostic resection may be required to differentiate atypical FNH from other liver tumors, such as hepatocellular adenoma (HCA). Therefore, improved noninvasive diagnostic methods are needed. We experienced 2 cases where combination of magnetic resonance elastography (MRE) and gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) helped diagnose FNH. A 36-year-old woman and 17-year-old boy with liver tumors measuring 40 mm in diameter each showed hypointense nodule centers, indicating a central scar, surrounded by hyperintense signals during the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI. To rule out HCA, we performed MRE and liver biopsy. On MRE, the mean stiffness of the mass was 11.6 kPa (mean stiffness of the background liver was 1.7 kPa) and 11.1 kPa (mean stiffness of the background liver was 2.4 kPa) in the first and second patients, respectively. Histological examination of both specimens showed CK7-positive bile-ductular proliferations, abundant fibrous tissue, and few Ki-67-positive cells. Based on these results, we diagnosed these tumors as FNH. Combination of Gd-EOB-DTPA-enhanced MRI and MRE can evaluate the character and stiffness of lesion and help in the diagnosis of FNH.

Synthesized HMGB1 peptide attenuates liver inflammation and suppresses fibrosis in mice

The liver has a high regenerative ability and can induce spontaneous regression of fibrosis when early liver damage occurs; however, these abilities are lost when chronic liver damage results in decompensated cirrhosis. Cell therapies, such as mesenchymal stem cell (MSC) and macrophage therapies, have attracted attention as potential strategies for mitigating liver fibrosis. Here, we evaluated the therapeutic effects of HMGB1 peptide synthesized from box A of high mobility group box 1 protein. Liver damage and fibrosis were evaluated using a carbon tetrachloride (CCl₄)-induced cirrhosis mouse model. The effects of HMGB1 peptide against immune cells were evaluated by single-cell RNA-seq using liver tissues, and those against monocytes/macrophages were further evaluated by in vitro analyses. Administration of HMGB1 peptide did not elicit a rapid response within 36 h, but attenuated liver damage after 1 week and suppressed fibrosis after 2 weeks. Fibrosis regression developed over time, despite continuous liver damage, suggesting that administration of this peptide could induce fibrolysis. In vitro analyses could not confirm a direct effect of HMGB1 peptide against monocyte/macrophages. However, macrophages were the most affected immune cells in the liver, and the number of scar-associated macrophages (Trem2+Cd9+ cells) with anti-inflammatory markers increased in the liver following HMGB1 treatment, suggesting that indirect effects of monocytes/macrophages were important for therapeutic efficacy. Overall, we established a new concept for cell-free therapy using HMGB1 peptide for cirrhosis through the induction of anti-inflammatory macrophages.

Molecular Mechanisms and Treatment of Sarcopenia in Liver Disease: A Review of Current Knowledge

Sarcopenia is characterized by progressive and generalized loss of skeletal muscle mass and strength that occurs with aging or in association with various diseases. The condition is prevalent worldwide and occurs more frequently in patients with chronic diseases owing to the intrinsic relationship of muscles with glucose, lipid, and protein metabolism. Liver cirrhosis is characterized by the progression of necro-inflammatory liver diseases, which leads to fibrosis, portal hypertension, and a catabolic state, which causes loss of muscle tissue. Sarcopenia is of significant concern in the state of liver cirrhosis because sarcopenia has been associated with higher mortality, increased hospital admissions, worse post-liver transplant outcomes, decreased quality of life, and increased risk for other complications associated with cirrhosis. Therefore, sarcopenia is also an important feature of liver cirrhosis, representing a negative prognostic factor and influencing mortality. An increased understanding of sarcopenia could lead to the development of novel therapeutic approaches that could help improve the cognitive impairment of cirrhotic patients; therefore, we present a review of the mechanisms and diagnosis of sarcopenia in liver disease and existing therapeutic approaches.

Esophageal Ulcers Associated with Ulcerative Colitis: A Case Series and Literature Review

Ulcerative colitis, a chronic and recurrent inflammatory disease, is localized to the colonic mucosa but can affect other organs and lead to various complications. Gastroduodenitis associated with ulcerative colitis has been reported. However, little is known about esophageal ulcers. We herein report two rare cases of esophageal ulcers associated with ulcerative colitis. Furthermore, the clinical and histological characteristics of 18 previously reported cases are summarized. This case series and literature review will encourage the accurate diagnosis and treatment of esophageal ulcers associated with ulcerative colitis.

Rare case of circumferential esophageal peeling

This report highlights the easy peeling of the esophageal epithelium with Nikolsky phenomenon after swallowing the foreign body and the healing status of the esophagus only 3 days later in a patient of pemphigus vulgaris.

Therapeutic potential of mesenchymal stem cells and their exosomes in severe novel coronavirus disease 2019 (COVID-19) cases

The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19) and the ensuing worldwide pandemic. The spread of the virus has had global effects such as activity restriction, economic stagnation, and collapse of healthcare infrastructure. Severe SARS-CoV-2 infection induces a cytokine storm, leading to acute respiratory distress syndrome (ARDS) and multiple organ failure, which are very serious health conditions and must be mitigated or resolved as soon as possible. Mesenchymal stem cells (MSCs) and their exosomes can affect immune cells by inducing anti-inflammatory macrophages, regulatory T and B cells, and regulatory dendritic cells, and can inactivate T cells. Hence, they are potential candidate agents for treatment of severe cases of COVID-19. In this review, we report the background of severe cases of COVID-19, basic aspects and mechanisms of action of MSCs and their exosomes, and discuss basic and clinical studies based on MSCs and exosomes for influenza-induced ARDS. Finally, we report the potential of MSC and exosome therapy in severe cases of COVID-19 in recently initiated or planned clinical trials of MSCs (33 trials) and exosomes (1 trial) registered in 13 countries on ClinicalTrials.gov.

Refractory hemorrhagic esophageal ulcers by Candida esophagitis with advanced systemic sclerosis

A 64-year-old woman diagnosed with rheumatoid arthritis (RA) and systemic sclerosis (SSc) was admitted to our hospital with chief complaints of uncontrolled bleeding from esophageal ulcers and an inability to consume meals. For RA and SSc, she was treated with prednisolone and abatacept and was taking vonoprazan as prophylaxis for steroid-induced gastric ulcers. She was diagnosed with severe Candida esophagitis, with multiple large and small ulcers with bleeding, based on esophagogastroduodenoscopy and pathological findings. We performed comprehensive treatment; abatacept was discontinued, and total parenteral nutrition was initiated along with antifungal therapy. Improvement in the esophageal ulcers was observed. Although severe Candida esophagitis is a rare condition, we should keep in mind that severe Candida esophagitis can occur in patients with an immunosuppressive compromised host and esophageal movement disorders such as SSc. Regular follow up by endoscopy and prophylactic treatment to prevent severe esophagitis may be necessary.

Stomach is a major source of circulating ghrelin, and feeding state determines plasma ghrelin-like immunoreactivity levels in humans

Ghrelin, an endogenous ligand for the GH secretagogue receptor, was isolated from rat stomach and is involved in a novel system for regulating GH release. Although previous studies in rodents suggest that ghrelin is also involved in energy homeostasis and that ghrelin secretion is influenced by feeding, little is known about plasma ghrelin in humans. To address this issue, we studied plasma ghrelin-like immunoreactivity levels and elucidated the source of circulating ghrelin and the effects of feeding state on plasma ghrelin-like immunoreactivity levels in humans. The plasma ghrelin-like immunoreactivity concentration in normal humans measured by a specific RIA was 166.0 +/- 10.1 fmol/ml. Northern blot analysis of various human tissues identified ghrelin mRNA found most abundantly in the stomach and plasma ghrelin-like immunoreactivity levels in totally gastrectomized patients were reduced to 35% of those in normal controls. Plasma ghrelin-like immunoreactivity levels were increased by 31% after 12-h fasting and reduced by 22% immediately after habitual feeding. In patients with anorexia nervosa, plasma ghrelin-like immunoreactivity levels were markedly elevated compared with those in normal controls (401.2 +/- 58.4 vs. 192.8 +/- 19.4 fmol/ml) and were negatively correlated with body mass indexes. We conclude that the stomach is a major source of circulating ghrelin and that plasma ghrelin-like immunoreactivity levels reflect acute and chronic feeding states in humans.

Stomach is a major source of circulating ghrelin, and feeding state determines plasma ghrelin-like immunoreactivity levels in humans

Ghrelin, an endogenous ligand for the GH secretagogue receptor, was isolated from rat stomach and is involved in a novel system for regulating GH release. Although previous studies in rodents suggest that ghrelin is also involved in energy homeostasis and that ghrelin secretion is influenced by feeding, little is known about plasma ghrelin in humans. To address this issue, we studied plasma ghrelin-like immunoreactivity levels and elucidated the source of circulating ghrelin and the effects of feeding state on plasma ghrelin-like immunoreactivity levels in humans. The plasma ghrelin-like immunoreactivity concentration in normal humans measured by a specific RIA was 166.0 +/- 10.1 fmol/ml. Northern blot analysis of various human tissues identified ghrelin mRNA found most abundantly in the stomach and plasma ghrelin-like immunoreactivity levels in totally gastrectomized patients were reduced to 35% of those in normal controls. Plasma ghrelin-like immunoreactivity levels were increased by 31% after 12-h fasting and reduced by 22% immediately after habitual feeding. In patients with anorexia nervosa, plasma ghrelin-like immunoreactivity levels were markedly elevated compared with those in normal controls (401.2 +/- 58.4 vs. 192.8 +/- 19.4 fmol/ml) and were negatively correlated with body mass indexes. We conclude that the stomach is a major source of circulating ghrelin and that plasma ghrelin-like immunoreactivity levels reflect acute and chronic feeding states in humans.

Crucial involvement of the EP4 subtype of prostaglandin E receptor in osteoclast formation by proinflammatory cytokines and lipopolysaccharide

Prostaglandin E2 (PGE2) exerts its effects through the PGE receptor that consists of four subtypes (EP1, EP2, EP3, and EP4). Osteoclast formation in the coculture of primary osteoblastic cells (POB) and bone marrow cells was enhanced more by 11-deoxy-PGE1 (an EP4 and EP2 agonist) than by butaprost (an EP2 agonist) and other agonists, which suggests that EP4 is the main factor in PGE2-induced osteoclast formation. PGE2-induced osteoclast formation was not observed in the coculture of POB from EP4-deficient (EP4 k/o) mice and spleen cells from wild-type (w/t) mice, whereas osteoclasts were formed in the coculture of POB from w/t mice and spleen cells from EP4-k/o mice. In situ hybridization (ISH) showed that EP4 messenger RNA (mRNA) was expressed on osteoblastic cells but not on multinucleated cells (MNCs) in w/t mice. These results indicate that PGE2 enhances osteoclast formation through its EP4 subtype on osteoblasts. Osteoclast formation by interleukin 1alpha (IL-1alpha), tumor necrosis factor alpha (TNF-alpha), basic fibroblast growth factor (bFGF), and lipopolysaccharide (LPS) was hardly observed in the coculture of POB and bone marrow cells, both from EP4-k/o mice, which shows the crucial involvement of PG and the EP4 subtype in osteoclast formation by these molecules. In contrast, osteoclast formation by 1,25-hydroxyvitamin D3 (1,25(OH)2D3) was not impaired and that by parathyroid hormone (PTH) was only partially impaired in EP4-k/o mice, which may be related to the fact that EP4-k/o mice revealed no gross skeletal abnormalities. Because it has been suggested that IL-1alpha, TNF-alpha, bFGF, and LPS are involved in inflammatory bone loss, our work can be expected to contribute to an understanding of the pathophysiology of these conditions.

Prostaglandin E2 (PGE2) autoamplifies its production through EP1 subtype of PGE receptor in mouse osteoblastic MC3T3-E1 cells

Prostaglandin E2 (PGE2) is known to autoamplify its production in the osteoblasts through the induction of prostaglandin G/H synthase-2 (PGHS-2), which is the inducible form of the rate-limiting enzyme in PG synthesis, PGHS. To elucidate the cellular mechanism mediating this process, we have employed the PGE2 analogs, which are specific agonists for four subtypes of PGE receptor, and studied the potency of these analogs to induce PGHS-2 mRNA in mouse osteoblastic MC3T3-E1 cells. The induction was mainly observed by 17-phenyl-omega-trinor PGE2 (EP1 agonist) and sulprostone (EP3/EP1 agonist), but not by butaprost (EP2 agonist) or 11-deoxy PGE1 (EP4/EP2 agonist). Since EP3 subtype was undetectable in MC3T3-E1 cells, these data indicate that PGHS-2 mRNA induction is mediated through EP1 subtype of PGE receptor in MC3T3-E1 cells. PGE2 production determined by radioimmunoassay was also increased by 17-phenyl-omega-trinor PGE2 and sulprostone. The autoamplification of PGE2 production is considered to be important in elongating the otherwise short-lived PGE2 action in certain physiological conditions such as mechanical stress and fracture healing, as well as the pathological inflammatory bone loss. The observations in the present study provide us with the better understanding of these processes.

Human leptin receptor gene in obese Japanese subjects: evidence against either obesity-causing mutations or association of sequence variants with obesity

Leptin is an adipocyte-derived blood-borne satiety factor that acts on its cognate leptin receptor (Ob-R) in the hypothalamus, thereby regulating food intake and energy expenditure. To explore whether mutations in the Ob-R gene cause obesity in humans, we have searched for mutations in the gene for Ob-Rb, a biologically active receptor isoform, in obese Japanese subjects. We have also examined associations between such mutants and obesity in the Japanese. Genomic DNAs were used as templates in polymerase chain reaction (PCR) with primers selected to amplify exons 2 to 20 of the human Ob-Rb gene. Direct sequence analysis of the PCR products revealed 7 nucleotide sequence variants (Lys109Arg, Gln223Arg, Ser343Ser, Ser492Thr, Lys656Asn, Ala976Asp, and Pro1019Pro) in the Ob-Rb coding region from 17 obese Japanese subjects with a family history of obesity (BMI 39.3 +/- 8.4 kg/m2). No missense and nonsense mutations were found such as those in Zucker fatty (fa/fa) rats and Koletsky (fa[k]/ fa[k]) rats. Nucleotide substitutions occurred at relatively high frequencies at codons 109, 223, 976, and 1019 (79, 91, 100, and 85%, respectively). Allele frequency of each variant determined by PCR-RFLP and PCR-single strand conformation polymorphism analyses showed no significant differences between 47 obese (BMI 35.1 +/- 6.5 kg/m2) and 68 non-obese (BMI 21.6 +/- 2.2 kg/m2) subjects. The present study represents the first report of sequence variants of the Ob-Rb gene in the Japanese and provides evidence against either obesity-causing mutations or association of sequence variants with obesity in obese Japanese subjects.

Spontaneous remission of primary hyperparathyroidism due to hemorrhagic infarction in the parathyroid adenoma

A 59-year-old man visited Kyoto University Hospital because of general malaise, polyuria, and polydipsia. The diagnosis of primary hyperparathyroidism was made based on hypercalcemia and an elevated circulating PTH level. A nodule was palpable in the left anterior neck. Two weeks later, the serum calcium level was normalized and his symptoms subsided. A temporary expansion, followed by reduction of the tumor size was observed by serial ultrasonography. Histology of the resected tumor showed central necrotic tissue, with some peripherally remaining glandular tissue. We report here a rare case of primary hyperparathyroidism with spontaneous remission due to hemorrhagic infarction in the adenoma.

Oxyphil parathyroid adenoma associated with primary hyperparathyroidism and marked post-operative hungry bone syndrome

A rare case of functioning oxyphil parathyroid adenoma associated with primary hyperparathyroidism and marked hungry bone syndrome was revealed in a 29-year-old man with hypercalcemia and elevated circulating parathyroid hormone (PTH) level. A large parathyroid tumor weighing 8.4 g was resected and proved to be an oxyphil adenoma. Hypocalcemia was sustained after the operation, despite intensive calcium supplementation. During the postoperative 8 months, bone mineral density at the lumbar spine increased dramatically from 0.892 g/cm2 to 1.244 g/cm2, and whole body bone mineral content increased from 1,913.4 g to 2,419.2 g. This case gives insight to the reversibility of bone loss in this disorder.

C-type natriuretic peptide as an autocrine/paracrine regulator of osteoblast. Evidence for possible presence of bone natriuretic peptide system

C-type natriuretic peptide (CNP) is a local regulator in the brain and vascular wall. We present data to demonstrate the production and action of CNP in the osteoblast. CNP increased cGMP production, far more potently than atrial natriuretic peptide (ANP) in an osteoblastic cell line, MC3T3-E1. Since ANP and CNP are the ligands for two particulate guanylate cyclases, guanylate cyclase-A (GC-A) and guanylate cyclase-B (GC-B), respectively, these results reveal the expression of GC-B in MC3T3-E1. In addition, CNP mRNA and CNP-like immunoreactivity were detected in cell extracts from MC3T3-E1 and its culture medium, respectively. Both CNP and 8-bromo cGMP dose-dependently decreased [3H]thymidine uptake, without affecting alkaline phosphatase activity. These results indicate that CNP is a novel autocrine/paracrine regulator of osteoblast and suggest the presence of "bone natriuretic peptide system."

Prostaglandin E receptor subtypes in mouse osteoblastic cell line

PGE2 is one of the key molecules in the osteoblast. It is the major prostanoid in the bone, and its production is under the control of both systemic and local factors. PGE2 has been reported to have multiple actions in the osteoblast, such as growth promotion and cell differentiation. To better understand the action of PGE2 in the osteoblast, we determined the PGE receptor subtypes in MC3T3-E1, an osteoblastic cell line derived from the normal mouse calvaria. Northern blot analysis revealed that EP1 and EP4 subtypes are expressed in MC3T3-E1. In contrast, EP3 subtype was not detected by either Northern blot analysis or RT-PCR. The contribution of each subtype was evaluated by studying the effects of subtype-specific analogs on osteoblastic function at confluency and 5 days after confluency. An EP1 agonist, 17-phenyl-omega-trinor PGE2, increased DNA synthesis and decreased alkaline phosphatase activity. 11-Deoxy-PGE1, and EP2 and EP4 agonist, decreased DNA synthesis and increased alkaline phosphatase activity at both stages. Butaprost, an EP2-selective agonist, showed effects similar to those of 11-deoxy-PGE1 only at confluency. Another and more differentiated osteoblastic marker, osteocalcin production, was detectable and was stimulated by 11-deoxy-PGE1 only 5 days after confluency. The exposure of these cells to EP1 agonist changed the cell shape to a more fibroblastic appearance. These results indicate that EP1, EP4, and probably EP2 are present in MC3T3-E1 cells; EP1 promotes cell growth, and EP2 and EP4 mediate differentiation of the osteoblast. Furthermore, the decreased response to EP2-specific agonist 5 days after confluency suggests that the expression of PGE receptor subtype is dependent on the stage of osteoblastic differentiation. This is the first report to determine PGE receptor subtypes in the bone.

The effect of 4-aminopyrazolo(3,4-d) pyrimidine on mouse plasma alpha-amylase activity

A single dose of 4-aminopyrazolo(3,4-d) pyrimidine (4APP), an adenine analog, was orally administered at various concentrations of groups of mice and after 24 h, the plasma-alpha-amylase activity and cholesterol levels had significantly decreased in a dose-dependent manner. There was no change, however, in pancreatic superoxide dismutase activity or the lipid peroxide level. Histologically, zymogen degranulation was found after a high oral dose of 4APP (175 mg/kg). The same decrease in alpha-amylase activity occurred in mice that had received ip administration of 4APP, and in mice that were pretreated with dimethyl sulfoxide. Based on these results, it appears that 4APP decreases plasma alpha-amylase activity dose-dependently, possibly by pancreatic injury, and that free radicals play no part in the observed changes.

The effects of adenine and dimethyl sulfoxide on the mouse pancreas

The authors have studied the effects of dimethyl sulfoxide (DMSO) on the plasma alpha-amylase activity in mice that sustained a pancreatic injury induced by an oral administration of adenine. In mice given a 5% solution of DMSO as drinking water for 3 d prior to the administration of adenine (175 mg/kg), and also drank this DMSO solution until the end of the experiment, hyperemia of the pancreas was observed and the level of plasma alpha-amylase activity became significantly higher than the level seen in the control mice. A pathological examination also revealed vacuolation and zymogenic degranulation. Further, the plasma alpha-amylase activity level increased only in mice given this 5% DMSO solution, and no increase was noted in mice given a 3% or a 1% DMSO solution for drinking water. Further, the pancreatic lipid peroxide level of mice given this 5% DMSO solution was significantly higher than the level seen in the control group. Based on the above results and associated data, it is thought that an oral administration of adenine can induce a pancreatic injury in the mouse, and that this injury is sustained with the assistance of DMSO.

Arachidonate 5-lipoxygenase of porcine pancreas: its localization in acinar cells

Arachidonate 5-lipoxygenase has been found so far in various types of leukocyte. When a homogenate of porcine pancreas was incubated with arachidonic acid, 5-hydroxy-6,8,11,14-eicosatetraenoic acid was predominantly produced concomitant with small amounts of compounds derived from leukotriene A4. After differential centrifugation of the homogenate, the 5-lipoxygenase activity was found predominantly in the 1000 x g pellet and 105,000 x g supernatant. When porcine pancreas was investigated immunohistochemically with anti-5-lipoxygenase antibody, Langerhans islets were unstained, and infiltration of 5-lipoxygenase-positive leukocytes was hardly observed. In contrast, acinar cells were positively stained. Immunoelectron microscopy demonstrated the localization of the enzyme along the nuclear membranes of the acinar cells.

Immunohistochemical study on arachidonate 5-lipoxygenase in porcine leukocytes and other tissues

Arachidonate 5-lipoxygenase is an enzyme that catalyzes the oxygenation of arachidonic acid, producing 5-hydroperoxy acid. This enzymatic reaction initiates the biosynthesis of various bioactive leukotrienes. An antiserum was raised in a rabbit against the purified 5-lipoxygenase of porcine leukocytes, and various types of porcine leukocytes were immunostained by use of the antibody. As examined by light and electron microscopy, neutrophils and eosinophils were positively stained. The 5-lipoxygenase was localized in the cytoplasm but not in the plasma membrane and subcellular organelles of the positively stained cells. In contrast, lymphocytes were unstained. In porcine ileum, the majority of 5-lipoxygenase-positive cells were eosinophils and mast cells resident in the lamina propria mucosae, whereas parenchymal cells were not stained. In porcine lung, certain bronchiolar or bronchial epithelial cells were clearly immunostained, in addition to eosinophils and mast cells found in the interstitium.

Localization of arachidonate 12-lipoxygenase in parenchymal cells of porcine anterior pituitary

12-Lipoxygenases oxygenate arachidonic acid producing its 12S-hydroperoxy derivative and are well known as platelet and leukocyte enzymes. When a peroxidase-linked immunoassay of the enzyme according to the avidin-biotin method was applied to the cytosol fractions from various parts of porcine brain, a considerable amount of the enzyme was found in the anterior pituitary. The enzyme level (about 200 ng/mg cytosol protein) corresponded to about 6% of the enzyme content in porcine peripheral leukocytes. Posterior and intermediate lobes showed about one-tenth of the enzyme level of anterior pituitary. Other parts of porcine brain contained the 12-lipoxygenase in amounts below 7 ng/mg cytosol protein. The cytosol fraction (0.7 mg of protein) of anterior pituitary produced 12S-hydroxy-5,8,10,14-eicosatetraenoic acid from 25 microM arachidonic acid in about 34% conversion at 24 degrees C for 5 min, giving a specific enzyme activity about 3 nmol/min/mg protein. Furthermore, various octadecapolyenoic acids were oxygenated almost as fast as the arachidonate 12-oxygenation. When anterior pituitary was investigated immunohistochemically with anti-12-lipoxygenase antibody, most of the immunostained cells were certain parenchymal cells with granules, which were not blood cells. These biochemical and immunohistochemical results provide a good reason for considering that 12-lipoxygenase does play an important role in pituitary function.