O-Linked N-Acetylglucosamine Transferase Ensures Survival of Mouse Fetal Liver Hematopoietic Progenitors Partly by Regulating Bcl-xL and Oxidative Phosphorylation

O-linked N-acetylglucosamine transferase (OGT) critically regulates wide variety of biological processes such as gene expression, metabolism, stress response, signaling and proteostasis. In adult hematopoiesis, OGT is crucial for differentiation of B and T cells and the maintenance of hematopoietic stem cells (HSCs). However, a role for OGT in fetal liver (FL) hematopoiesis remains unknown. To investigate a role for OGT in FL hematopoiesis, we conditionally disrupted OGT in hematopoietic cells in developing FLs. Hematopoietic specific disruption of OGT resulted in embryonic lethality in late stage of gestation due to severe anemia and growth retardation. OGT loss led to profound reduction of differentiating erythroid cells and erythroid progenitors in FLs due to massive apoptosis. In addition, clonogenic capacity of FL cells was severely impaired by OGT loss. Interestingly, expression of BCL-XL, a well-known inhibitor of apoptosis in FL cells, dramatically decreased, and the levels of reactive oxygen species (ROS) were increased in OGT-deficient FL cells. Overexpression of Bcl-xL and reduction of ROS significantly restored the colony formation of OGT-deficient FL cells. This study revealed a novel role for OGT during embryogenesis, which ensures survival of FL hematopoietic cells partly by regulating Bcl-xL and oxidative phosphorylation.

Peripheral Parenteral Nutrition and Activities of Daily Living in Hospitalized Older Frail Patients

BACKGROUND

Frail older adults require nursing care following hospitalization for acute illnesses. Frailty is reversible, and appropriate nutritional management and rehabilitation during hospitalization are essential. However, optimal nutritional management for patients who are unable to obtain adequate nutrition via oral intake has not been established. We aimed to determine whether peripheral parenteral nutrition (PPN) promotes the recovery of activities of daily living (ADLs) in frail older patients.

METHODS

This was a retrospective, observational cohort study conducted at the General Medicine Department of Aomori Prefectural Central Hospital in Aomori, Japan. The primary outcome was recovery of the Barthel index (BI) from the beginning of rehabilitation to discharge, and the secondary outcomes were the proportion of patients transferred for rehabilitation and the nutritional status.

RESULTS

In total, 342 patients hospitalized during the period of April 2018 to January 2022 were included, of whom 127 (37.1%) received PPN and 215 (62.9%) did not. Contrary to our expectations, recovery of the BI was lower in the PPN group than that in the non-PPN group (12.2 (95% confidence interval (CI): 8.5-16.0) vs. 22.4 (18.8-23.0); p < 0.01). Multivariable analysis revealed PPN as an independent risk factor for poor BI recovery (mean difference = -7.3 (95% CI = -12.7 to -1.9)).

CONCLUSION

Nutritional management through PPN for frail older adults may not improve physical activity. The nutritional management of frail patients with inadequate oral intake remains challenging.

Pericardial Effusion and Progressive Bilateral Effusion as Rare Presentations of Idiopathic Hypereosinophilic Syndrome

Hypereosinophilic syndrome (HES) is a rare disease with peripheral blood eosinophils >1500/µL and end-organ damage. We encountered a case of idiopathic HES in a woman in her 60s who presented with dyspnea due to cardiac effusion and bilateral pleural effusions. At first, the patient did not have eosinophilia in the peripheral blood, and the presence of serum pericardial fluid and pleural effusion led to suspicion of carcinomatous pericarditis and pleurisy. One month later after onset, eosinophilia in the peripheral blood was observed, and HES was suspected for the first time. However, inflammatory cell infiltration by eosinophils has been observed in the pleural fluid specimen before eosinophilia in the peripheral blood. Prednisolone was administered, and the pleural effusion and respiratory failure quickly abated. This case provided an educational illustration of a unique manifestation of cardiac tamponade and HES, characterized by the absence of peripheral blood eosinophilia at the initial presentation.

Community-Acquired Severe Clostridium difficile Enteritis Complicated by Metabolic Acidosis and Acute Kidney Injury

Clostridium difficile (CD) is known to be pathogenic when the balance of intestinal microbiota is disrupted by the administration of broad-spectrum antimicrobial agents. Therefore, CD enteritis is often suspected in cases of hospital-onset diarrhea. There has been a rise in the incidence of community-acquired CD enteritis in recent years in the United States. In this report, we present a case of a 57 year-old-man who was admitted to the emergency department with abdominal distension and dyspnea. The patient suffered from acute renal failure and metabolic acidosis from enteritis. He required mechanical ventilation and continuous renal replacement therapy (CRRT) in the ICU. Analysis of the patient's stool sample on admission revealed the presence of CD antigens, and the prompt administration of metronidazole led to swift improvement. No studies have investigated the actual incidence of community-acquired CD enteritis infection in Japan. Since 20% of community-acquired CD enteritis cases have been reported as severe, all cases of community-acquired enteritis should raise concerns for CD enteritis. CD antigen/toxin in the stool should then be determined promptly before administering antibiotics.

Aortic dissection diagnosed with the aortic dissection detection risk score of 2 without D-dimer elevation

Acute aortic dissection can be fatal if overlooked, and the absence of D-dimer elevation can be used to exclude acute aortic dissection. However, we report a case of acute aortic dissection without D-dimer elevation. A man in his 70s presented to the emergency department with lumbar back pain. D-dimer was <1.0 µg/mL; however, acute aortic dissection was strongly suspected because of the sudden onset of lumbar back pain with a shifting location. Because of a difference in systolic blood pressure in both upper extremities, we performed a thorough examination using contrast-enhanced CT, leading to a diagnosis of acute aortic dissection. The patient was immediately referred to cardiovascular surgery and treated conservatively with antihypertensive management. The aortic dissection detection risk score (ADD-RS) classified the patient as high risk. This suggests the importance of using the D-dimer with the ADD-RS rather than solely relying on the D-dimer results to diagnose acute aortic dissection.

Multiple Myeloma With a Rare Presentation at Preserved Uninvolved Immunoglobulins

Multiple myeloma is a neoplastic disease of plasma cells that produces monoclonal immunoglobulins, known as monoclonal proteins, causing hypercalcemia, anemia, renal insufficiency, bone lesion, and other organ damage. In most multiple myeloma, the amount of monoclonal protein correlates with the tumor burden and reflects its prognosis. Uninvolved immunoglobulins are often suppressed as monoclonal protein levels increase as a result of the increasing percentage of myeloma cells in the bone marrow. Detection of monoclonal protein by protein electrophoresis, immunofixation, and serum-free light chain assay is a highly sensitive analysis and is not suitable as a screening test because it is positive in a few percent of healthy elderly people, the majority of whom are classified as benign monoclonal gammopathy of undetermined significance. Therefore, it is widely used in practice to measure quantitation of immunoglobulins by nephelometer, and only when uninvolved immunoglobulins are decreasing in the values for each subtype, monoclonal protein identification by immunofixation, serum-free light chain assay, and bone marrow examination must be additionally performed for proactively diagnosing multiple myeloma. However, we experienced symptomatic multiple myeloma in which uninvolved immunoglobulins were not suppressed and there were no significant changes in immunoglobulin levels despite the relatively rapid progression. It would suggest that if you suspect symptomatic myeloma, you should not rule out the possibility of multiple myeloma because of preserved uninvolved immunoglobulins in laboratory findings.

OGT Regulates Hematopoietic Stem Cell Maintenance via PINK1-Dependent Mitophagy

O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) is a unique enzyme introducing O-GlcNAc moiety on target proteins, and it critically regulates various cellular processes in diverse cell types. However, its roles in hematopoietic stem and progenitor cells (HSPCs) remain elusive. Here, using Ogt conditional knockout mice, we show that OGT is essential for HSPCs. Ogt is highly expressed in HSPCs, and its disruption induces rapid loss of HSPCs with increased reactive oxygen species and apoptosis. In particular, Ogt-deficient hematopoietic stem cells (HSCs) lose quiescence, cannot be maintained in vivo, and become vulnerable to regenerative and competitive stress. Interestingly, Ogt-deficient HSCs accumulate defective mitochondria due to impaired mitophagy with decreased key mitophagy regulator, Pink1, through dysregulation of H3K4me3. Furthermore, overexpression of PINK1 restores mitophagy and the number of Ogt-deficient HSCs. Collectively, our results reveal that OGT critically regulates maintenance and stress response of HSCs by ensuring mitochondrial quality through PINK1-dependent mitophagy.

[Emphysema evaluation of the remaining lung post lobectomy]

The aim of this study was to confirm that the emphysematous changes had increased in the remaining lung on the operation side after lobectomy. Fourteen patients underwent quantitative analysis by computed tomography (CT) and respiratory function testing before and after the operation for upper or lower lobectomy of the lung between March 2005 and May 2007. The degree of emphysema was calculated by dividing the volume of the emphysematous region (CT values: -1,024 to -950 HU) by the volume of the entire lung (CT values: -1,024 to -600 HU) using a 1 mm thickness high resolution CT slice. Comparison by paired t-test showed significant differences between the emphysema rates pre and post operation in the operation side lung (15.3 +/- 7.9% and 21.7 +/- 10.0%, p = 0.02), but there were no significant differences in the contralateral lung (15.8 +/- 7.5% and 17.7 +/- 8.4%, p = 0.25). On the other hand, there was no significant change in the percent forced expiratory volume in one second (FEV1.0%) between pre and post operation (74.4 +/- 10.5% and 75.5 +/- 7.5%, p = 0.60). We consider that it is necessary to note that the emphysematous changes increased in the remaining lung on the operation side after lobectomy even though the FEV1.0% did not decrease at present.

Effects of genistein and herbimycin, tyrosine kinase inhibitors, on catecholamine release in bovine adrenal chromaffin cells

1 The effects of genistein and herbimycin, tyrosine kinase inhibitors, on catecholamine (CA) release were examined in bovine adrenal chromaffin cells. 2 In intact cells, genistein (10-100 microm) and herbimycin (3-30 microm) inhibited CA release induced by acetylcholine (ACh; 100 microm) or the nicotinic receptor stimulant 1,1-dimethyl-4-phenyl-piperazinium (DMPP; 10 microm), but did not affect CA release induced by high K+ (40 mm). 3 Genistein and herbimycin inhibited (45)Ca2+ uptake induced by ACh (100 microm). 4 Neither genistein nor herbimycin affected [(3)H]nicotine binding with nicotinic receptors. 5 In beta-escin-permeabilized cells, neither genistein nor herbimycin affected CA release induced by Ca2+ (1 microm). 6 These results suggest that protein tyrosine kinase plays the facilitatory role in the regulation of CA release induced by nicotinic receptor stimulation in stimulus-secretion coupling of bovine adrenal chromaffin cells.

Discrepant distribution of big endothelin (ET)-1 and ET receptors in the pulmonary artery

Since pulmonary vasculature is complex in terms of regional difference in structure and function, it is important to understand the site of endothelin (ET) synthesis and the distribution of the ET system along the axial pathways of pulmonary artery. The expression of big ET-1, ET converting enzyme (ECE) and ET(A) receptors were examined in rat pulmonary arteries under normal and hypoxic conditions using an immunohistochemical method and Northern blot analysis. In normal conditions, big ET-1 was expressed in the intima and media of pulmonary arteries with a predominant distribution in the distal segments and a preferential localization in the media, while ETA receptors were dominantly expressed in the proximal segments. ECE was constitutively expressed in the intima and media. Following exposure to hypoxia, messenger ribonucleic acid (mRNA) expression of ET-1 and ET(A) receptors were up-regulated by two-fold and immunoreactivities for big ET-1, ECE, and ET(A) receptors significantly increased by two to five-fold in the distal segments. Smooth muscle cells are an important source of endothelin-1 in the pulmonary artery. The distribution of big endothelin-1 and endothelin A receptors in pulmonary arteries was discrepant in normal conditions while their expression concomitantly increased in the distal segments in hypoxic conditions. This heterogeneity may play an important role in the regulation of pulmonary vascular tone.

Upregulation of ET-1 and its receptors and remodeling in small pulmonary veins under hypoxic conditions

Pulmonary veins show greater sensitivity to endothelin (ET)-1-induced vasoconstriction than pulmonary arteries, and remodeling was observed in pulmonary veins under hypoxic conditions. We examined, using an immunohistochemical method, the expression of Big ET-1, ET-converting enzyme (ECE), and ET(A) and ET(B) receptors in rat pulmonary veins under normoxic and hypoxic conditions. In control rats, Big ET-1 and ECE were coexpressed in the intima and media of the pulmonary veins, with an even distribution along the axial pathway. ET(A) and ET(B) receptors were expressed in the pulmonary veins, with a predominant distribution in the proximal segments. The expression of Big ET-1 was more abundant in the pulmonary veins than in the pulmonary arteries. After exposure to hypoxia for 7 or 14 days, the expression of Big ET-1, ECE, and ET receptors increased in small pulmonary veins. Increases in the medial thickness, wall thickness, and immunoreactivity for alpha-smooth muscle actin were also observed in the small pulmonary veins under hypoxic conditions. The upregulation of ET-1 and ET receptors in the small pulmonary veins is associated with vascular remodeling, which may lead to the development of hypoxic pulmonary hypertension.

Local and chronic application of PTH accelerates tooth movement in rats

We previously reported that whereas systemic continuous infusion of parathyroid hormone (PTH) accelerated orthodontic tooth movement, systemic but intermittent injection of PTH did not increase the rate of tooth movement. Analysis of these data suggested that continuous administration of PTH could be applicable for orthodontic therapy. In the present study, we investigated whether local and chronic application of PTH(1-34) would accelerate orthodontic tooth movement. To increase the residence time of PTH in the injected area, we used methylcellulose (MC) gel (2% W/V) for a slow-release formulation of PTH. MC gel containing PTH (PTH-MC) continuously released biologically active PTH into the acceptor medium for more than 72 hrs in vitro. When male rats received a local injection of PTH-MC into the subperiosteum in the mesio-palatal region of the maxillary first molar (M1) every other day, M1 movement, which was mesially drawn by an orthodontic coil spring attached to the maxillary incisors, was accelerated in a dose-dependent manner. PTH-MC injection at 1 microg/400 g body weight caused a 1.6-fold increase in the rate of tooth movement. The acceleration of tooth movement by PTH-MC injection was marked on days 6, 9, and 12. Local injection of PTH dissolved in saline without MC did not significantly accelerate tooth movement on day 6 or later. Histological examination revealed active osteoclastic bone resorption and a widened periodontal space on the compression side of the periodontal tissue in the PTH-MC-injected rats. These results suggest that local injection of PTH in a slow-release formulation is applicable to orthodontic therapy.

Somatic mutation of the PTEN/MMAC1 gene in breast cancers with microsatellite instability

The extent to which microsatellite instability (MI) contributes to the etiology of breast cancer has not been established in any large-scale studies. We examined 528 samples of tumor DNA from patients with primary breast cancer for MI, using 14 polymorphic CA-repeat markers. The frequency of MI in these tumors was unexpectedly low (10/528, 1.9%). The ten MI+ tumors were analyzed for mutations in five potential target genes that contain simple repeat sequences (TGFBIIR, IGF2R, hMSH6, BAX and PTEN/MMAC1). A somatic insertion of an extra adenine in the (A)6 region at codon 321-323 (exon 8) of the PTEN/MMAC1 gene, leading to a frame-shift, was identified in one tumor. This observation represented the first documented instance of PTEN/MMAC1 alteration in a MI+ primary breast cancer.

Comparison between observation policy and fractionated stereotactic radiotherapy (SRT) as an initial management for vestibular schwannoma

PURPOSE

To compare the use of an observation policy with that of stereotactic radiotherapy (SRT) for treatment of vestibular schwannoma.

METHODS AND MATERIALS

The study group consisted of 27 patients who underwent observation as an initial treatment (observation group) and 50 who received SRT (SRT group). The mean follow-up period was 35 months and 31 months, respectively. Stereotactic radiotherapy consisted of small-field fractionated radiotherapy (36-44 Gy in 20-22 fractions over 6 weeks) with or without a subsequent 4-Gy single irradiation boost.

RESULTS

Actuarial tumor control rate of the SRT group was significantly better than that of the observation group (p < 0.0001). The mean growth was 3.87 mm/year in the observation group and -0.75 mm/year in the SRT group (p < 0.0001). Eleven patients (41 %) in the observation group and 1 (2 %) in the SRT group received salvage therapy (p < 0.001). There was no difference in the actuarial Gardner and Robertson's class preservation curves for 5 years after the initial presentation.

CONCLUSION

Stereotactic radiotherapy using a fractionated schedule provides a better tumor control rate and a similar rate of deterioration for hearing levels compared to an observation policy. Initial SRT may be a reasonable alternative to a wait-and-see policy.

Localization and distribution of endothelin receptor subtypes in pulmonary vasculature of normal and hypoxia-exposed rats

To clarify the roles of two different endothelin (ET) receptors in the pulmonary vasculature, the localization and distribution of endothelin-A (ETA) and ETB receptors were investigated in rat lung under normal and hypoxic conditions by an immunohistochemical method. We also carried out in situ hybridization for ETB receptor. In normal rats, ETA receptor is localized in the media of the pulmonary artery and vein with predominant distribution in such proximal segments as elastic arteries and large muscular arteries. ETB receptor is expressed in the intima and media of pulmonary vessels. The distribution of ETB receptor in the media predominates in the distal segments of the pulmonary artery, whereas its distribution in the intima is greater in the proximal segments. Immunoreactivity for ETA receptor increases in the media of the distal segments of the pulmonary artery after exposure to hypobaric hypoxia. Semiquantitative evaluation showed immunoreactivity for ETA receptor in the pulmonary arteries accompanying the terminal bronchioles, respiratory bronchioles, and alveolar ducts to be increased by 2.5-, 5-, and 20-fold after 14 d exposure to hypoxia, respectively. The messenger RNA and immunoreactivity for ETB receptor increased significantly in the intima of the distal segments of pulmonary artery after 7 and 14 d exposure to hypoxia. These results suggest that the vasoconstrictive effects of ET-1 are exerted mainly through ETA receptor in the proximal segments of the pulmonary artery and vein, whereas its effects in the distal segments are mediated by ETA and ETB receptors in normal rats. ETA receptors that increase in resistance arteries after exposure to hypoxia appear to play an important role in the vascular remodeling associated with hypoxic pulmonary hypertension. Because ETB receptors in the endothelium mediate ET-1-induced vasodilatory effects, the increase in endothelial ETB receptors may counteract the development of hypoxic pulmonary hypertension.

Effects of continuous infusion of PTH on experimental tooth movement in rats

Development of new methods for accelerating orthodontic tooth movement has been strongly desired for shortening of the treatment period. The rate of orthodontic tooth movement is dependent on the rate of bone resorption occurring in the compressed periodontium in the direction of orthodontic force applied to the tooth. In the present study, we examined the effects of continuous infusion of parathyroid hormone (PTH) on tooth movement. Male rats weighing 350-400 g were treated with subcutaneous of vehicle or hPTH(1-84) at 1-10 micrograms/100 g of body weight/day. When the upper right first molar (M1) was moved mesially for 72 h by the insertion of an elastic band between the first and second molars, M1 movement was accelerated by PTH infusion at 10 micrograms. PTH infusion caused a 2- to 3-fold increase in the number of osteoclasts in the compressed periodontium of M1, indicating that such treatment accelerated tooth movement by enhancing bone resorptive activity induced in the compressed periodontium. When M1 was moved mesially by an orthodontic coil spring ligated between upper incisors and M1 for 12 days, PTH(1-84) infusion at 10 micrograms caused a 2-fold increase in the rate of M1 movement. PTH(1-34) infusion at 4 micrograms had an effect comparable to that of PTH(1-84). However, intermittent injection of PTH(1-34) did not accelerate M1 movement. PTH infusion for 13 days did not affect either bone mineral measurements or the serum calcium level. These findings suggest that continuous administration of PTH is applicable to accelerate orthodontic tooth movement.

Chronic hypoxia augments endothelin-B receptor-mediated vasodilation in isolated perfused rat lungs

To investigate whether chronic hypoxia affects endothelin-B (ETB) receptor-mediated pulmonary vasodilation, we compared the vasodilator responses to IRL-1620, a selective ETB-receptor agonist, in isolated perfused lungs from normoxic and chronically hypoxic adult male rats. IRL-1620 caused a dose-dependent vasodilation that was greater in the hypertensive lungs than in the normotensive lungs. In normotensive lungs, a nitric oxide (NO) synthase inhibitor, Nomega-nitro-L-arginine (L-NNA; 300 microM), and an ATP-sensitive potassium (KATP)-channel inhibitor, glibenclamide (Glib; 10 microM), each reduced the vasodilator response to IRL-1620 (1 nM), but the combination of L-NNA and Glib inhibited it more effectively than either drug alone. In contrast, L-NNA alone, but not Glib alone, completely blocked IRL-1620-induced vasodilation in hypertensive lungs. The vasodilator response to a KATP-channel opener, NIP-121 (1 microM), but not the response to sodium nitroprusside (1 microM), was enhanced in hypertensive lungs. We also found increased expression of mRNA for the ETB receptor in lung tissue after hypoxic exposure. In addition, semiquantitative immunohistochemistry demonstrated higher expression levels of ETB receptors in the endothelium of distal segments of the pulmonary artery in hypoxic than in normoxic rats. These results suggest that ETB receptor-mediated pulmonary vasodilation is augmented after chronic hypoxic exposure and that release of NO may be the sole mechanism of this vasodilation in hypertensive lungs, whereas both release of NO and activation of KATP channels are involved in normotensive lungs. We speculate that the underlying mechanism responsible for this augmentation may partly be related to upregulation of ETB receptors in the endothelium of pulmonary resistance arteries in hypertensive lungs.

Prevention of pulmonary embolization during excision of an infected venous thrombus

We describe the case of a 64-year-old woman with an iatrogenic pseudoaneurysm, arteriovenous fistula, and thrombotic occlusion of the right femoral vein with Staphylococcus aureus infection resistant to methicillin as complications of femoral catheterization for hemodialysis access. A temporary caval filter was introduced just prior to operation and kept in place for 4 days. An infected thrombus was captured and removed with a filter-catheter device. The placement of a temporary caval filter should be considered for prevention of pulmonary embolism in patients with infected venous thrombosis which requires surgical thrombectomy.

Enhancement by conditioned medium of stretched calvarial bone cells of the osteoclast-like cell formation induced by parathyroid hormone in mouse bone marrow cultures

To investigate whether mechanical deformation of osteoblasts exerts an influence upon parathyroid hormone (PTH)-induced bone resorption, the effect of medium conditioned by a statistically stretched, osteoblast-enriched, bone cell population on PTH-induced osteoclast-like cell formation in mouse bone marrow cultures was examined. The conditioned medium of stretched cultures stimulated bone marrow cells to differentiate into tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells in the presence of 10(-8) M PTH(1-34). The stimulatory effect of the conditioned medium was significant when the bone cells were stretched at 2 mm deflection in the 90% subconfluent state. Conditioned medium from cultures in the 50% subconfluent state failed to enhance osteoclast-like cell formation. PTH-induced, TRAP-positive multinuclear cells were decreased in number by the addition of stretch-conditioned medium in the postconfluent state. When 10(-6) M indomethacin was added to bone cell cultures during stretching, the resulting conditioned medium suppressed PTH-induced, TRAP-positive multinuclear cell formation. However, even if 10(-8) M prostaglandin E2 was added to the stretched bone cell cultures along with the indomethacin, the resulting conditioned medium did not reverse the suppression of the PTH-induced, osteoclast-like cell formation. These findings suggest that bone resorption in response to continuous mechanical deformation is regulated by cells of the osteoblast lineage such as preosteoblasts, osteoblasts, bone lining cells and osteocytes in vivo, and that prostaglandins, but not prostaglandins E2, are involved in the stretch-enhanced, osteoclast-like cell formation.

Altered vasoreactivity in lungs isolated from rats exposed to nitric oxide gas

A rebound phenomenon (severe arterial desaturation and pulmonary vasoconstriction) has been observed in some patients with pulmonary hypertension after sudden discontinuation of nitric oxide (NO) inhalation therapy. The mechanism responsible for this phenomenon is unknown. It has recently been reported that NO synthase (NOS) can be inhibited by NO as a negative feedback mechanism. We therefore hypothesized that this rebound phenomenon might be attributable to reduced endogenous NO production due to inhibition of pulmonary endothelial NOS (eNOS) activity by inhaled NO. To test this hypothesis, vasoreactivities were compared in isolated perfused lungs from rats exposed to 40 ppm NO gas and room air for 2 days. The pressor responses to angiotensin II and hypoxia of lungs from rats exposed to NO were markedly potentiated and their depressor response to bradykinin was considerably impaired, whereas that to sodium nitroprusside was preserved, compared with the responses of those exposed to room air. This altered pulmonary vasoreactivity was also induced by lower concentrations of inhaled NO (as low as 1 ppm) and was completely reversed by discontinuation of NO inhalation for several (< 8) hours. The expression of eNOS mRNA by lungs isolated from rats exposed to 40 ppm NO and room air for 2 days did not differ. These results suggest that pulmonary endogenous NO production is reversibly reduced after relatively short-term NO inhalation, which probably inhibits eNOS activity directly. We speculate that reduced production of pulmonary endogenous NO by exogenous (inhaled) NO could be the mechanism responsible for this rebound phenomenon.

Effects of salvia miltiorrhiza bunge (SMB) on MC3T3-E1 cells

In previous research, we found that the Salvia Miltiorrhiza Bunge (SMB), a traditional Chinese medicinal herb, accelerates orthodontic tooth movement. In the present study, to characterize the actions of SMB on bone remodeling, we investigated the effect of SMB on DNA synthesis and alkaline phosphatase activity of murine osteoblast like cell-clone, MC3T3-E1 cells in vitro. Treatment of the cells with SMB for 72 hours caused significant increase in ALPase activity. It was found that SMB increased ALPase activity in a dose-dependent manner, and up to maximum at the concentration of 5.0 mg/ml. At that concentration, ALPase activity was about 135% greater than that of control. SMB at 5.0 mg/ml significantly stimulated ALPase activity of the cells in multilayer on day 8 or calcification stage on day 16, but inhibited it in the sparse stage on day 2 or subconfluency stage on day 4. SMB had no effect on DNA synthesis in any stage of culture. ALPase activity significantly increased at 48 hours and was up to 300% greater than that of control activity at 96 hours. These findings suggest that SMB directly stimulates ALPase activity of MC3T3-E1 cells in multilayer stage or calcification stage without any effect on proliferation. Locally administrated SMB may affect the differentiation of osteoblasts in vivo.

Stimulation of alkaline phosphatase activity by ascorbic acid and suppression by 1,25-dihydroxycholecalciferol in rabbit craniofacial chondrocytes in culture

To clarify the role of vitamins D and C in chondrocyte hypertrophy of craniofacial cartilage, we have studied cultured chondrocytes from rabbit mandibular condylar cartilage (MCC), sphenooccipital synchondrosis (SOS) and nasal septal cartilage (NSC) under conditions in which these cells mature into hypertrophic chondrocytes. In cultures of MCC- and SOS-chondrocytes, alkaline phosphatase (ALPase) activity started to increase on day 9 at confluence and the cessation of cell division, and reached a maximum on day 18. The degree of the increase of ALPase activity on day 18 was higher in MCC-chondrocytes than in SOS-chondrocytes. ALPase activity was very low level in NSC- and CGC-chondrocytes. Ascorbic acid induced a marked increase in ALPase activity in MCC-, SOS-, NSC- and CGC-chondrocytes. The ALPase activities in MCC- and SOS-chondrocytes with 50 micrograms/ml ascorbic acid were 2.5-times those in its absence. Those in NSC- and CGC-chondrocytes were 10 times and 20 times, respectively. When chondrocytes were cultured with 10% charcoal-treated serum, ALPase activity decreased less than that in cultures with 10% normal serum in MCC-, SOS-, NSC- and CGC-chondrocytes. Treatment of 1,25-(OH)2D3 for 9 days from days 4 to 13 in MCC-chondrocytes and for 14 days from days 4 to 18 in SOS-, NSC- and CGC-chondrocytes inhibited ALPase activity dose-dependently at the concentrations of 10(-12) M to 10(-8) M in MCC- chondrocytes, 10(-10) M to 10(-8) M in SOS- and CGC-chondrocytes, 10(-11) M to 10(-9) M in NSC-chondrocytes. These findings suggest that 1,25-(OH)2D3 and ascorbic acid may be involved in the control of cartilage growth and terminal differentiation.

Comparison of the effects of hydrostatic compressive force on glycosaminoglycan synthesis and proliferation in rabbit chondrocytes from mandibular condylar cartilage, nasal septum, and spheno-occipital synchondrosis in vitro

We have developed a simple in vitro model whereby precise quantities of compressive force can be applied to cultured chondrocytes from craniofacial cartilage: mandibular condylar cartilage (MCC), nasal septal cartilage (NSC), and spheno-occipital synchondrosis (SOS). Using this model, we found that hydrostatic compressive force stimulated glycosaminoglycan (GAG) synthesis, a cartilage phenotype, in MCC and SOS chondrocytes and DNA synthesis in MCC, NSC, and SOS chondrocytes. These stimulations were dependent on force magnitude and duration, reaching maximal GAG synthesis at 27 hours and maximal DNA synthesis at 20 hours after application of force. The maximal increase of GAG synthesis induced by compressive force was about 60% at 100 gm/cm2 for 5 minutes in nonstimulated MCC chondrocytes and 40% at 50 gm/cm2 for 1 minute in nonstimulated SOS chondrocytes. The maximal increase in DNA synthesis, produced by a compressive force of 50 gm/cm2 for 1 minute, was 50% in NSC chondrocytes, 50% in SOS chondrocytes, and 30% in MCC chondrocytes. There was no stimulation of GAG synthesis in NSC chondrocytes. These observations suggest that extrinsic force regulates craniofacial growth by controlling the differentiation and proliferation of chondrocytes in the craniofacial skeleton and that the difference in their responses to compressive force may reflect differences in the characteristics of these cells and their physiologic function in vivo.

[Effects of hydrostatic pressure on proliferation and expression of the differentiated phenotype of cultured chondrocytes derived from rabbit craniofacial complex]

To investigate the effects of mechanical forces on the growth of cartilages of the craniofacial complex, chondrocytes isolated from nasal septal cartilage (NSC), spheno-occipital synchondrosis (SOS), and mandibular condylar cartilage (MCC) were cultured and exposed to hydrostatic pressure in vitro. Following results were obtained. 1. By application of the pressure, DNA synthesis increased in NSC and SOS (150% of control by 50 g/cm2, 1 min), but not so much in MCC in the medium containing 10% fetal calf serum (FCS). On the other hand, GAG synthesis increased in SOS (140% of control by 50 g/cm2, 2 min.) and MCC (160% of control by 100 g/cm2, 5 min), but decreased slightly in NSC in the same condition. The stimulations in DNA and GAG syntheses reached maxima 20-22 hr and 24-27 hr respectively after the application of the pressure. These stimulatory effects of the hydrostatic pressure on DNA and GAG syntheses could be found when cultured chondrocytes were in a multilayer stage. 2. It has been reported that addition of FCS at a concentration of 10% increases DNA synthesis in these chondrocytes preincubated in medium containing 0.3% FCS. The application of the pressure 2 min before the addition of 10% FCS potentiated the increase by FCS of DNA synthesis in NSC (130% of control), but not so much that in SOS and little that in MCC. 3. When the pressure was applied on these cells 2 min before addition of parathyroid hormone (PTH; 10(-7) M), this mechanical stimulation potentiated the increase by PTH of GAG synthesis in MCC (130% of control), but not so much that in SOS, and little that in NSC. Moreover, the intracellular cAMP level which was increased just after the addition of PTH also became higher by the application of the pressure. 4. These potentiation by the hydrostatic pressure in the cases of the addition of FCS and PTH diminished when intervals between application of pressure and addition of these factors were more than 10 min. These findings suggested that mechanical forces have influences on the growth of cartilages in craniofacial complex and that these effects are mediated by factors contained in serum.