Recurrent neonatal sepsis and progressive white matter injury in a premature newborn culture-positive for group B Streptococcus: A case report

RATIONALE

Group B Streptococcus (GBS) remains a principal pathogen causing neonatal sepsis and meningitis, particularly in premature infants with relatively insufficient immunity. Recurrence may occur uncommonly, largely associated with subclinical mucosal persistence or repetitive exposure to exogenous sources. White matter injury (WMI) including cystic periventricular leukomalacia (PVL) has been associated with intrauterine infection/inflammation, and neonatal infection as a more significant predictor including postnatal sepsis and recurrent infection, even without microbial neuroinvasion. Furthermore, clinical and experimental evidence of WMI by some bacteria other than GBS without central nervous system invasion has been reported. However, there is little evidence of WMI associated with neonatal GBS sepsis in the absence of meningitis in the literature.

PATIENT CONCERNS

A newborn at 30+4 weeks' gestation with low birthweight presented with 2 episodes (with a 13-day interval with no antibiotic therapy) of neonatal sepsis culture-proven for GBS with early-onset presentation after clinical chorioamnionitis via vertical GBS transmission and the associated conditions including prematurity-related neonatal immunodeficiency and persistent mucosal GBS carriage after the first antibiotic treatment. The perinatal GBS infection was complicated by progressive WMI presenting with ventriculomegaly and cystic PVL without a definite evidence of meningitis, intraventricular hemorrhage, and documented cerebral hypoxia or hypoperfusion conditions including septic shock.

DIAGNOSES

Recurrent group B streptococcal sepsis and cystic PVL with ventriculomegaly.

INTERVENTIONS

Two episodes of GBS sepsis were treated with 15-day parenteral antibiotic therapy, respectively.

OUTCOMES

Resolution of the recurrent GBS sepsis without further relapses, however, complicated by WMI and subsequent about 6 months delay in motor development at 12 months' corrected age.

LESSONS

This case suggests WMI associated with GBS bacteremia without central nervous system entry by viable GBS and also shows that in premature infants, intrauterine GBS infection with no interventions may lead to extensive and persistent GBS colonization, early-onset and recurrent GBS disease, and WMI. Postnatal as well as intrauterine infection/inflammation controls with maternal prophylaxis may be pivotal for prevention and limiting the magnitude of neurologic injury.

Clinical predictors of chest radiographic abnormalities in young children hospitalized with bronchiolitis: a single center study

Purpose

Chest radiography is often performed on patients hospitalized with typical clinical manifestations of bronchiolitis. We aimed to determine the proportion of subjects with pathologic chest radiographic findings and the clinical predictors associated with pathologic chest radiographic findings in young children admitted with the typical presentation of bronchiolitis.

Methods

We obtained the following data at admission: sex, age, neonatal history, past history of hospitalization for respiratory illnesses, heart rate, respiratory rate, the presence of fever, total duration of fever, oxygen saturation, laboratory parameters (i.e., complete blood cell count, high-sensitivity C-reactive protein [hs-CRP], etc.), and chest radiography.

Results

The study comprised 279 young children. Of these, 26 had a chest radiograph revealing opacity (n=24) or atelectasis (n=2). Multivariate logistic regression analysis showed that after adjustment for confounding factors, the clinical predictors associated with pathologic chest radiographic findings in young children admitted with bronchiolitis were elevated hs-CRP level (>0.3 mg/dL) and past history of hospitalization for respiratory illnesses (all P<0.05).

Conclusion

The current study suggests that chest radiographs in young children with typical clinical manifestations of bronchiolitis have limited value. Nonetheless, young children with clinical factors such as high hs-CRP levels at admission or past history of hospitalization for respiratory illnesses may be more likely to have pathologic chest radiographic findings.

Eckols reduce dental pulp inflammation through the ERK1/2 pathway independent of COX-2 inhibition

OBJECTIVES

The aim of this study was to elucidate the role of 6-6 bieckol (EB1) and pholorofucofuroeckol-A (EB5) from brown seaweed marine algae (Eisenia bicyclis) on lipopolysaccharide (LPS)-induced inflammation in human dental pulp cells (HDPCs).

METHODS

The cytotoxicity of EB1 and EB5 was examined by MTT assay on LPS-induced human dental pulp cells. Their role on expression of inflammatory, odontogenic, and osteogenic molecules was determined by Western blot analysis. The dentin mineralization was checked by alkaline phosphatase activity.

RESULTS

The five compounds from E. bicyclis have different structure with non-cytotoxic in HDPCs. EB1 and EB5 showed anti-inflammatory properties and inhibited phosphorylated-extracellular signal-regulated kinase (p-ERK1/2) and phosphorylated-c-jun N-terminal kinases (p-JNK) without any cytotoxicity. In particular, EB1 inhibited cyclooxygenase-2 (COX-2) and p-ERK1/2 signaling, and EB5 inhibited only p-ERK1/2 signaling but not COX-2. Both compounds inhibited nuclear factor kappa-B (NF-κB) translocation. Furthermore, EB1 and EB5 increased dentinogenic and osteogenic molecules, and dentin mineralized via alkaline phosphatase activity (ALP) in LPS-induced HDPCs.

CONCLUSIONS

This study elucidates that EB1 and EB5 have different types of anti-inflammatory property and help in dentin formation. Therefore, these compounds derived from marine algae of E. bicyclis may be used as selective therapeutic strategies for pulpitis and oral diseases.

Endovascular coil embolization of aneurysms with a branch incorporated into the sac

BACKGROUND AND PURPOSE

Because of the concern for occlusion of the incorporated branch artery, an aneurysm with a branch incorporated into the sac has been regarded as a contraindication for coiling. The aim of this study is to evaluate the feasibility, techniques, and clinical and angiographic outcomes of coiling for aneurysms with a branch incorporated into the sac.

MATERIALS AND METHODS

The medical records and radiologic studies of 69 patients with 79 aneurysms having a branch incorporated into the sac (26 ruptured, 53 unruptured) were retrospectively reviewed and evaluated.

RESULTS

Coiling was accomplished in 78 aneurysms in 68 patients but was suspended in 1 due to incorporated branch occlusion. The aneurysms were treated by using the following techniques: single-catheter (n = 37), multicatheter (n = 22), balloon-remodeling (n = 7), stent-assisted coiling (n = 6), and combined (n = 7). Postembolization angiography revealed the following: near-complete occlusion in 71 (89.8%), remnant neck in 4 (5.1%), and incomplete occlusion in 4 (5.1%) aneurysms. Procedure-related permanent morbidity and mortality rates were 5.8% (4/69) and 0%, respectively. All patients with unruptured aneurysms had a modified Rankin Scale (mRS) score of 0, except for 1 patient who had an mRS score of 3. Of the 26 patients with ruptured aneurysms, 18 had favorable outcome (mRS 0-2) but 8 had poor outcome (mRS 3-6). Follow-up angiography was available at least once at 6-50 months (mean, 15 months) in 55 aneurysms (69.6%), of which 45 showed stable or improved occlusion; 4, minor recurrences; and 6, major recurrences. All 6 major recurrent aneurysms were retreated without complication by using a single-catheter (n = 1), multicatheter (n = 2), or balloon-assisted technique (n = 3).

CONCLUSIONS

With appropriate techniques, most aneurysms with a branch incorporated into the sac could be safely treated by coiling, with acceptable outcomes.

Effect of cytoplasmic lipid content on in vitro developmental efficiency of bovine IVP embryos

The objective was to evaluate the effect of cytoplasmic lipid content on the embryonic developmental efficiency of bovine in vitro embryo production (IVP) embryos. Ovaries from Korean native cows (Bos taurus coreanae) were collected from a local abattoir, and cumulus-oocyte complexes (COCs) were recovered from follicles 2 to 8mm in diameter. The oocytes were divided into three groups, dependent on their cytoplasm color: pale color (PC), brown color (BC), and dark color (DC). The COCs were fertilized using frozen-thawed semen from a single Hanwoo bull. Based on measurement of the cytoplasmic color intensity of oocytes after 22h of in vitro maturation (IVM), the DC group had lower (P<0.05) color intensity than that in the BC and PC groups (56.3+/-2.7, 93.3+/-5.1, and 123.9+/-12.0, respectively). Based on MitoTracker Green FM staining, the number of mitochondria in the DC (170.1+/-31.2) group was significantly higher than that in the BC (137.5+/-30.8) and PC (105.5+/-25.3) groups. The cleavage rate in the DC (81.5%) group was also higher than that in the PC (50.4%) group (P<0.05), as was the development rate to blastocyst stage (18.9% vs. 9.8%). Finally, cell numbers of blastocysts in the DC (150.8+/-28.0) group were higher (P<0.05) than that in the BC (107.6+/-17.8) and PC (80.5+/-12.3) groups. In conclusion, cytoplasm color was a useful selection parameter for abattoir-derived oocytes destined for IVP.

Sonographic evaluation of neonates with early-stage necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in neonatal intensive care units. Ultrasonographic findings in early-stage NEC have not been described.

OBJECTIVE

To assess the diagnostic value of ultrasonography for the diagnosis and monitoring of patients with NEC.

MATERIALS AND METHODS

We evaluated the sonographic findings of early stages of NEC in 40 neonates who were clinically diagnosed with NEC when they were 2-28 days old. Their average gestational age was 32 weeks, and their mean weight was 1,850 g. All of the patients showed signs of bowel distention on abdominal radiography, with no evidence of pneumatosis intestinalis. We performed bowel sonography in all patients (n = 40), as well as in ten healthy neonates who served as a control group. The studies were conducted with a 10-MHz linear transducer from February 2003 to January 2004. We evaluated the echogenicity of the bowel wall, involved region, ascites, and portal venous gas at both initial and follow-up examinations. We divided the patients into two groups according to the bowel wall echogenicity pattern, group I with echogenic dots in the bowel wall and group II with dense granular echogenicities in the bowel wall. In order to identify any correlations between the ultrasonography and clinical findings, we evaluated the duration of parenteral feeding (NPO) in each group and compared two groups by means of a statistical analysis (Mann-Whitney test).

RESULTS

All of the neonates in the control group (n = 10) presented normal bowel wall echogenicity; the patients with NEC presented echogenic dots in 16 patients (40%) and dense granular echogenicities in 24 patients (60%). Portal venous gas was absent in all patients. On the follow-up examinations, the echogenicity of the bowel wall and ascites decreased in 37 patients (93%). The duration of NPO was 11.1 +/- 6.6 days in group I and 16.5 +/- 7.2 days in group II (P < 0.05).

CONCLUSION

Echogenic dots or dense granular echogenicities in the bowel wall can be seen in patients with early-stage NEC. Bowel sonography can be helpful for the early diagnosis and monitoring of patients with NEC.

Unilateral breast edema: spectrum of etiologies and imaging appearances

Breast edema is defined as a mammographic pattern of skin thickening, increased parenchymal density, and interstitial marking. It can be caused by benign or malignant diseases, as a result of a tumor in the dermal lymphatics of the breast, lymphatic congestion caused by breast, lymphatic drainage obstruction, or by congestive heart failure. Here we describe several conditions, that cause unilateral breast edema with the aim of familiarizing radiologists with these disease entities.

Isolated echogenic foci in the left upper quadrant of the fetal abdomen: are they significant?

OBJECTIVES

To evaluate fetuses with echogenic foci in the left upper quadrant of the abdomen by sonographic examination.

METHODS

Between November 2000 and October 2001, we prospectively assessed fetuses with echogenic foci in the abdominal left upper quadrant on routine prenatal sonography. The location, number, and size of the foci were analyzed, and in utero and postpartum follow-up scans were performed. A pediatrician evaluated the perinatal outcome.

RESULTS

Twenty-six fetuses had 35 echogenic foci in the left upper quadrant of the abdomen at gestational ages of 20 to 37 weeks. The locations of the foci along the stomach, spleen, and the left lobe of the liver were found on sonography and measured 2 to 5 mm. Of the 16 fetuses who had follow-up scans in utero, 7 had disappearance of the foci. Postpartum follow-up scans were performed in 12 cases. Among them, 9 neonates had no lesions, and 3 had echogenic foci of a size and appearance similar to those seen prenatally in the left lobe of the liver. Only 1 of 4 patients who had TORCH (toxoplasmosis, other, rubella, cytomegalovirus, and herpes simplex) titers evaluated had elevated immunoglobulin G levels; no patient had any sign of infection after birth. All fetuses had a normal postnatal outcome.

CONCLUSIONS

Many echogenic foci in the left upper quadrant of the fetal abdomen will disappear, and the outcome is promising even when the lesion persists after birth.

Expression and secretion of the heterodimeric protein interleukin-12 in plant cell suspension culture

It has been suggested that plant cell culture is the most suitable system for producing small-to-medium quantities of specialized, expensive, and high-purity proteins. Here, we report that a heterodimeric protein, human interleukin-12 (hIL-12), was expressed and secreted into culture medium in a biologically active form. A transgenic plant expressing hIL-12 was constructed by sexual crossing of plants that expressed each subunit of the protein. From a piece of transgenic plant, callus was induced and cell suspension culture was established. The biological activity and amount of hIL-12 secreted into culture medium were analyzed using bioassays and ELISA. Analysis of cellular localization demonstrated that the protein was secreted into the culture medium together with its intrinsic signal peptide.

Immunolocalization of aquaporin-8 in rat kidney, gastrointestinal tract, testis, and airways

The purpose of this study was to determine the cellular and subcellular localization of aquaporin-8 (AQP8) in rat kidney and other organs by RT-PCR analyses and by immunoblotting and immunohistochemistry using peptide-derived rabbit antibodies to rat AQP8. RT-PCR and Southern blotting revealed the presence of AQP8 mRNA in all kidney zones. LLC-PK(1) cells transfected with a rat AQP8 construct exhibited strong labeling with the affinity-purified antibodies, whereas controls using cells transfected with the vector, but without the insert, were negative. The labeling was almost exclusively associated with intracellular vesicles. Immunoblotting of kidney membrane fractions revealed a predominant single band of 26-28 kDa. AQP8 immunoreactivity was mainly present in the cortex and outer stripe of the outer medulla. Sequential ultracentrifugation of rat kidney membrane revealed that AQP8 resides predominantly in intracellular vesicular fractions. Immunocytochemistry revealed modest labeling of proximal tubules and weak labeling of collecting ducts in cortex and medulla of rat kidney. The labeling was confined to cytoplasmic areas with no labeling of the brush border. Immunoblotting and RT-PCR/Southern blotting also revealed the presence of AQP8 protein and mRNA in rat liver, testis, epididymis, duodenum, jejunum, colon, and bronchi/trachea. Consistent with this, immunohistochemistry revealed AQP8 labeling in the hepatocytes and spermatogenic cells in testis and in the basal cells in ductus epididymis, trachea, and bronchial epithelia. Moreover, AQP8 labeling was observed in the myoepithelial cells in salivary, bronchial, and tracheal glands with no labeling of acini or ductal epithelial cells. AQP8 is also present in the surface epithelial cells in duodenum, jejunum, and colon. In conclusion, AQP8 is expressed at low levels in rat kidney proximal tubules and collecting ducts, and it is present in distinct cell types in liver, testis, epididymis, duodenum, jejunum, colon, trachea, and principal bronchi as well as in multiple glands, including salivary glands.

Accumulation of intraventricular fat in an intracranial epidermoid tumor: case report

OBJECTIVE AND IMPORTANCE

A fat component within the ventricles or subarachnoid space in fat-containing tumors such as an epidermoid or a dermoid has been observed in rare instances. However, there have been no reports regarding an increase in the size of such a fat component. We describe the case of an epidermoid tumor with intraventricular fat that showed an increase in size and amount.

CLINICAL PRESENTATION

A 26-year-old woman was admitted with headache and diplopia. Computed tomography and magnetic resonance imaging of the brain revealed a fat-containing suprasellar tumor and widespread fat globules in adjacent sulci and cisterns and within the frontal horn of the lateral ventricle.

INTERVENTION

The patient underwent a pterional craniotomy. Removal of the suprasellar tumor was nearly total. Histopathological examination revealed an epidermoid tumor. Sequential magnetic resonance imaging throughout the ensuing 65-month period revealed no evidence of tumor recurrence; however, the intraventricular fat remained and increased in size. The patient underwent surgery via the transcallosal approach at 69 months after the initial operation, and the presence of free-floating oily fat globules was confirmed.

CONCLUSION

In the case of a fat-containing tumor with free fat in the cerebrospinal fluid spaces, careful serial examination is necessary, with particular attention to the possibility of changes in size.

The renal thiazide-sensitive Na-Cl cotransporter as mediator of the aldosterone-escape phenomenon

The kidneys "escape" from the Na-retaining effects of aldosterone when circulating levels of aldosterone are inappropriately elevated in the setting of normal or expanded extracellular fluid volume, e.g., in primary aldosteronism. Using a targeted proteomics approach, we screened renal protein extracts with rabbit polyclonal antibodies directed to each of the major Na transporters expressed along the nephron to determine whether escape from aldosterone-mediated Na retention is associated with decreased abundance of one or more of renal Na transporters. The analysis revealed that the renal abundance of the thiazide-sensitive Na-Cl cotransporter (NCC) was profoundly and selectively decreased. None of the other apical solute-coupled Na transporters displayed decreases in abundance, nor were the total abundances of the three ENaC subunits significantly altered. Immunocytochemistry showed a strong decrease in NCC labeling in distal convoluted tubules of aldosterone-escape rats with no change in the cellular distribution of NCC. Ribonuclease protection assays (RPAs) revealed that the decrease in NCC protein abundance was not associated with altered NCC mRNA abundance. Thus, the thiazide-sensitive Na-Cl cotransporter of the distal convoluted tubule appears to be the chief molecular target for regulatory processes responsible for mineralocorticoid escape, decreasing in abundance via a posttranscriptional mechanism.

Identification and localization of aquaporin water channels in human salivary glands

Aquaporin (AQP) water channels are expressed in a variety of fluid-transporting epithelia and are likely to play a significant role in salivary secretion. Our aim was to identify and localize the aquaporins expressed in human salivary glands. Total RNA was extracted from human parotid, submandibular, sublingual, and labial glands and from human brain. Expression of aquaporin mRNA was assessed by RT-PCR using specific primers for human AQP1, AQP3, AQP4, and AQP5. All four aquaporins were detected by RT-PCR in all of the glands, and the sequences were confirmed after further amplification with nested primers. Cleaned PCR products were then used as (32)P-labeled cDNA probes in a semiquantitative Northern blot analysis using glyceraldehyde-3-phosphate dehydrogenase as reference. Only AQP1, AQP3, and AQP5 mRNAs were present at significant levels. AQP localization was determined by immunohistochemistry on paraffin sections using affinity-purified primary antibodies and peroxidase-linked secondary antibodies. Each salivary gland type showed a broadly similar staining pattern: AQP1 was localized to the capillary endothelium and myoepithelial cells; AQP3 was present in the basolateral membranes of both mucous and serous acinar cells; AQP4 was not detected; and AQP5 was expressed in the luminal and canalicular membranes of both types of acinar cell. We conclude that AQP3 and AQP5 together may provide a pathway for transcellular osmotic water flow in the formation of the primary saliva.

Downregulation of AQP1, -2, and -3 after ureteral obstruction is associated with a long-term urine-concentrating defect

Previously, we demonstrated that 24 h of bilateral ureteral obstruction (BUO) and short-term release of BUO was associated with a decrease in the expression of aquaporin-2 (AQP2), polyuria, and a reduced urinary concentrating capacity (10). The purposes of the present study were to examine whether BUO and the long-term release of BUO (BUO-R) for 3, 14, and 30 days were associated with changes in the expression of renal AQP1, AQP2, and AQP3 and whether such changes were associated with parallel changes in urinary output and urinary concentrating capacity. Rats (n = 4-7 in each group) were kept in metabolic cages for measurements of urinary output. Kidneys were removed to determine the expression levels of AQP1, AQP2, and AQP3 by semiquantitative immunoblotting. AQP2 was downregulated after 24 h of BUO (42 +/- 3%). Downregulation of AQP2 persisted 3 (43 +/- 14%; P < 0.01) and 15 days after BUO-R (48 +/- 11%; P < 0.01) but was normalized 30 days after BUO-R. AQP3 showed a similar pattern. Moreover, AQP1 was downregulated in response to BUO (65 +/- 7%) and remained downregulated 3 days after BUO-R (41 +/- 5%), 14 days after BUO-R (57 +/- 8%), and 30 days after BUO-R (59 +/- 5%). BUO-R resulted in a significant polyuria that gradually decreased, although it remained significant at day 30. Urinary concentrating capacity remained significantly impaired when determined 3, 14, and 30 days after BUO-R in response to a 24-h period of thirst (1,712 +/- 270 vs. 2,880 +/- 91 mosmol/kgH2O at day 30, P < 0.05). In conclusion, the expression of AQP1, AQP2, and AQP3 were long-term downregulated after BUO-R, suggesting that dysregulation of aquaporins located at the proximal tubule, thin descending limb of the loop of Henle, and the collecting duct may contribute to the long-term polyuria and impairment of urinary concentrating capacity associated with obstructive nephropathy.

Altered expression of renal aquaporins and Na+ transporters in rats treated with L-type calcium blocker

Nifedipine, a calcium antagonist, has diuretic and natriuretic properties. However, the molecular mechanisms by which these effects are produced are poorly understood. We examined kidney abundance of aquaporins (AQP1, AQP2, and AQP3) and major sodium transporters [type 3 Na/H exchanger (NHE-3); type 2 Na-Pi cotransporter (NaPi-2); Na-K-ATPase; type 1 bumetanide-sensitive cotransporter (BSC-1); and thiazide-sensitive Na-Cl cotransporter (TSC)] as well as inner medullary abundance of AQP2, phosphorylated-AQP2 (p-AQP2), AQP3, and calcium-sensing receptor (CaR). Rats treated with nifedipine orally (700 mg/kg) for 19 days had a significant increase in urine output, whereas urinary osmolality and solute-free water reabsorption were markedly reduced. Consistent with this, immunoblotting revealed a significant decrease in the abundance of whole kidney AQP2 (47 ± 7% of control rats, P< 0.05) and in inner medullary AQP2 (60 ± 7%) as well as in p-AQP2 abundance (17 ± 6%) in nifedipine-treated rats. In contrast, whole kidney AQP3 abundance was significantly increased (219 ± 28%). Of potential importance in modulating AQP2 levels, the abundance of CaR in the inner medulla was significantly increased (295 ± 25%) in nifedipine-treated rats. Nifedipine treatment was also associated with increased urinary sodium excretion. Consistent with this, semiquantitative immunoblotting revealed significant reductions in the abundance of proximal tubule Na+ transporters: NHE-3 (3 ± 1%), NaPi-2 (53 ± 12%), and Na-K-ATPase (74 ± 5%). In contrast, the abundance of the distal tubule Na-Cl cotransporter (TSC) was markedly increased (240 ± 29%), whereas BSC-1 in the thick ascending limb was not altered. In conclusion, 1) increased urine output and reduced urinary concentration in nifedipine-treated-rats may, in part, be due to downregulation of AQP2 and p-AQP2 levels; 2) CaR might be involved in the regulation of water reabsorption in the inner medulla collecting duct; 3) reduced expression of proximal tubule Na+ transporters (NHE-3, NaPi-2, and Na, K-ATPase) may be involved in the increased urinary sodium excretion; and 4) increase in TSC expression may occur as a compensatory mechanism.

Immunocytochemical and immunoelectron microscopic localization of α-, β-, and γ-ENaC in rat kidney

Epithelial sodium channel (ENaC) subunit (α, β, and γ) mRNA and protein have been localized to the principal cells of the connecting tubule (CNT), cortical collecting duct (CCD), and outer medullary collecting duct (OMCD) in rat kidney. However, the subcellular localization of ENaC subunits in the principal cells of these cells is undefined. The cellular and subcellular localization of ENaC subunits in rat kidney was therefore examined. Immunocytochemistry demonstrated the presence of all three subunits in principal cells of the CNT, CCD, OMCD, and IMCD. In cortex and outer medulla, confocal microscopy demonstrated a difference in the subcellular localization of subunits. α-ENaC was localized mainly in a zone in the apical domains, whereas β- and γ-ENaC were found throughout the cytoplasm. Immunoelectron microscopy confirmed the presence of ENaC subunits in both the apical plasma membrane and intracellular vesicles. In contrast to the labeling pattern seen in cortex, α-ENaC labeling in IMCD cells was distributed throughout the cytoplasm. In the urothelium covering pelvis, ureters, and bladder, immunoperoxidase and confocal microscopy revealed differences the presence of all ENaC subunits. As seen in CCD, α-ENaC was present in a narrow zone near the apical plasma membrane, whereas β- and γ-ENaC were dispersed throughout the cytoplasm. In conclusion, all three subunits of ENaC are expressed throughout the collecting duct (CD), including the IMCD as well as in the urothelium. The intracellular vesicular pool in CD principal cells suggests ENaC trafficking as a potential mechanism for the regulation of Na+ reabsorption.

Physiology and pathophysiology of renal aquaporins

The discovery of aquaporin-1 (AQP1) by Agre and associates answered the longstanding biophysical question of how water specifically crosses biological membranes. In the kidney at least 7 aquaporins are expressed at distinct sites. AQP1 is extremely abundant in the proximal tubule and descending thin limb and is essential for urinary concentration. AQP2 is exclusively expressed in the principal cells of the connecting tubule and collecting duct and is the predominant vasopressin-regulated water channel. AQP3 and AQP4 are both present in the basolateral plasma membrane of collecting duct principal cells and represent exit pathways for water reabsorbed apically via AQP2. Studies in patients and transgenic mice have shown that both AQP2 and AQP3 are essential for urinary concentration. Three additional aquaporins are present in the kidney. AQP6 is present in intracellular vesicles in collecting duct intercalated cells and AQP8 are present intracellularly at low abundance in proximal tubules and collecting duct principal cells but the physiological function of these 2 channels remain undefined. AQP7 is abundant in the brush border of proximal tubule cells and is likely to be involved in proximal tubule water reabsorption. A series of studies have underscored crucial roles of aquaporins for regulation of renal water metabolism and hence body water balance. Moreover it has become clear that dysregulation of aquaporins, and especially AQP2 is critically involved in many water balance disorders. Lack of functional AQP2 is seen in primary forms of diabetes insipidus, and reduced expression and targeting is seen in several diseases associated with urinary concentrating defects such as acquired nephrogenic diabetes insipidus, postobstructive polyuria, as well as acute and chronic renal failure. In contrast, in conditions with water retention such as severe congestive heart failure, pregnancy and SIADH both AQP2 expression levels and apical plasma membrane targetting is increased suggesting a role for AQP2 in the development of water retention. Continued analysis of the aquaporins is providing detailed molecular insight into the fundamental physiology and pathophysiology of water balance and water balance disorders.

Distal anterior cerebral artery aneurysms: clinical features and surgical outcome

Aneurysms of the distal anterior cerebral artery (DACA) are rare and their surgical treatments present some unique difficulties from a technical standpoint. In this report, we presented our experiences of cases with DACA aneurysms, and analyzed the clinical features and prognostic factors affecting the final outcomes. Among 770 cases of intracranial aneurysms operated from 1990 to 1998, 19 cases of DACA aneurysms (2.5%) were studied retrospectively. The characteristic findings were female preponderance (M:F = 1:2.8), common multiple aneurysms (57.9%), and frequent intracerebral hemorrhage (ICH) on initial brain CT scan (42.1%). All patients were operated via interhemispheric approach. Intraoperative aneurysmal rupture was developed only in 3 cases (15.8%), and had no relationship with the final outcome Fifteen out of 19 patients (78.9%) showed favorable outcome with a mortality rate of 5.3%. The follow-up data suggest that the initial ICH on brain CT scan portend a poor prognosis.

Expression and immunolocalization of aquaporin water channels in rat exocrine pancreas

Both the acinar and ductal cells of the pancreas secrete a near-isotonic fluid and may thus be sites of aquaporin (AQP) water channel expression. Northern blot analysis of mRNA from whole rat pancreas revealed high levels of AQP1 and AQP8 expression, whereas lower levels of AQP4 and AQP5 expression were just detectable by RT-PCR Southern blot analysis. Immunohistochemistry showed that AQP1 is localized in the microvasculature, whereas AQP8 is confined to the apical pole of the acinar cells. No labeling of acinar, ductal, or vascular tissue was detected with antibodies to AQP2-7. With immunoelectron microscopy, AQP8 labeling was observed not only at the apical membrane of the acinar cells but also among small intracellular vesicles in the subapical cytoplasm, suggesting that there may be regulated trafficking of AQP8 to the apical plasma membrane. To evaluate the contribution of AQPs to the membrane water permeability, video microscopy was used to measure the swelling of acinar cells in response to hypotonic stress. Osmotic water permeability was reduced by 90% following exposure to Hg(2+). Since AQP8 is confined to the apical membrane, the marked effect of Hg(2+) suggests that other water channels may be expressed in the basolateral membrane.

Compensatory increase in AQP2, p-AQP2, and AQP3 expression in rats with diabetes mellitus

Diabetes mellitus (DM) is associated with osmotic diuresis and natriuresis. At day 15, rats with DM induced by streptozotocin (n = 13) had severe hyperglycemia (27.1 +/- 0.4 vs. 4.7 +/- 0.1 mM in controls) and had a fivefold increase in water intake (123 +/- 5 vs. 25 +/- 2 ml/day) and urine output. Semiquantitative immunoblotting revealed a significant increase in inner medullary AQP2 (201 +/- 12% of control rats, P < 0.05) and phosphorylated (Ser(256)) AQP2 (p-AQP2) abundance (299 +/- 32%) in DM rats. Also, the abundance of inner medullary AQP3 was markedly increased to 171 +/- 19% of control levels (100 +/- 4%, n = 7, P < 0.05). In contrast, the abundance of whole kidney AQP1 (90 +/- 3%) and inner medullary AQP4 (121 +/- 16%) was unchanged in rats with DM. Immunoelectron microscopy further revealed an increased labeling of AQP2 in the apical plasma membrane of collecting duct principal cells (with less labeling in the intracellular vesicles) of DM rats, indicating enhanced trafficking of AQP2 to the apical plasma membrane. There was a marked increase in urinary sodium excretion in DM. Only Na(+)/H(+) exchanger NHE3 was downregulated (67 +/- 10 vs. 100 +/- 11%) whereas there were no significant changes in abundance of type 2 Na-phosphate cotransporter (128 +/- 6 vs. 100 +/- 10%); the Na-K-2Cl cotransporter (125 +/- 19 vs. 100 +/- 10%); the thiazide-sensitive Na-Cl cotransporter (121 +/- 9 vs. 100 +/- 10%); the alpha(1)-subunit of the Na-K-ATPase (106 +/- 7 vs. 100 +/- 5%); and the proximal tubule Na-HCO(3) cotransporter (98 +/- 16 vs. 100 +/- 7%). In conclusion, DM rats had an increased AQP2, p-AQP2, and AQP3 abundance as well as high AQP2 labeling of the apical plasma membrane, which is likely to represent a vasopressin-mediated compensatory increase in response to the severe polyuria. In contrast, there were no major changes in the abundance of AQP1, AQP4, and several major proximal and distal tubule Na(+) transporters except NHE3 downregulation, which may participate in the increased sodium excretion.

Enhanced iron uptake of Saccharomyces cerevisiae by heterologous expression of a tadpole ferritin gene

We genetically engineered Saccharomyces cerevisiae to express ferritin, a ubiquitous iron storage protein, with the major heavy-chain subunit of tadpole ferritin. A 450-kDa ferritin complex can store up to 4,500 iron atoms in its central cavity. We cloned the tadpole ferritin heavy-chain gene (TFH) into the yeast shuttle vector YEp352 under the control of a hybrid alcohol dehydrogenase II and glyceraldehyde-3-phosphate dehydrogenase promoter. We confirmed transformation and expression by Northern blot analysis of the recombinant yeast, by Western blot analysis using an antibody against Escherichia coli-expressed TFH, and with Prussian blue staining that indicated that the yeast-expressed tadpole ferritin was assembled into a complex that could bind iron. The recombinant yeast was more iron tolerant in that 95% of transformed cells, but none of the recipient strain cells, could form colonies on plates containing 30 mM ferric citrate. The cell-associated concentration of iron was 500 microg per gram (dry cell weight) of the recombinant yeast but was 210 microg per gram (dry cell weight) in the wild type. These findings indicate that the iron-carrying capacity of yeast is improved by heterologous expression of tadpole ferritin and suggests that this approach may help relieve dietary iron deficiencies in domesticated animals by the use of the engineered yeast as a feed and food supplement.

Regulation of AQP6 mRNA and protein expression in rats in response to altered acid-base or water balance

In the rat, aquaporin-6 (AQP6) is mainly localized in intercalated cells (ICs) in collecting ducts, where it is exclusively associated with intracellular vesicles. In this study, we examined whether AQP6 protein and mRNA expression were regulated in the inner medulla or inner stripe of the outer medulla. Rats treated with dietary alkali or acid load for 7 days with a fixed daily water intake revealed appropriate changes in urine pH but unchanged urine output. AQP6 protein and mRNA abundance were increased in alkali-loaded rats (187 +/- 18 and 151 +/- 17% of control, respectively), whereas no changes were observed in acid-loaded rats. Immunohistochemistry revealed increased IC AQP6 labeling in alkali-loaded rats but not in acid-loaded rats. In contrast, administration of NH(4)Cl in the drinking water for 2 wk (free access to water) revealed a significant increase in AQP6 protein abundance (194 +/- 9% of control), but this was associated with increased water intake. Combined, this suggests that AQP6 expression was not affected by acid loading per se but rather was in response to changes in water intake. Consistent with this, water loading for 48 h was associated with increased AQP6 protein abundance, compared with thirsted rats. Moreover, rats with lithium-induced nephrogenic diabetes insipidus had a threefold increase in both AQP6 protein and mRNA expression. Overall, these results suggest that AQP6 expression in collecting duct ICs is regulated by altered acid/alkali load or water balance. Thus AQP6 may contribute to maintenance of acid-base homeostasis and water balance.

The alpha(1G)-subunit of a voltage-dependent Ca(2+) channel is localized in rat distal nephron and collecting duct

The molecular type and localization of calcium channels along the nephron are not well understood. In the present study, we assessed the distribution of the recently identified alpha(1G)-subunit encoding a voltage-dependent calcium channel with T-type characteristics. Using a RNase protection assay, alpha(1G)-mRNA levels in kidney regions were determined as inner medulla >> outer medulla congruent with cortex. RT-PCR analysis of microdissected rat nephron segments revealed alpha(1G) expression in the distal convoluted tubule (DCT), in the connecting tubule and cortical collecting duct (CT+CCD), and inner medullary collecting duct (IMCD). alpha(1G) mRNA was expressed in the IMCD cell line mIMCD-3. Single- and double-labeling immunohistochemistry and confocal laser microscopy on semithin paraffin sections of rat kidneys by using an anti-alpha(1G) antibody demonstrated a distinct labeling at the apical plasma membrane domains of DCT cells, CT principal cells, and IMCD principal cells.

Renal water handling in rats with decompensated liver cirrhosis

The present study was performed to investigate the renal handling of water in rats with decompensated liver cirrhosis. Liver cirrhosis was induced by intraperitoneal administration of carbon tetrachloride twice weekly for 16 wk. Control rats were treated with vehicle. The cirrhotic rats developed severe disturbances in water homeostasis: urine production was decreased and hyperosmotic, the rats had significantly decreased plasma sodium concentration and ascites, and the ability to excrete an intravenous water load was significantly impaired. Plasma concentrations of vasopressin and aldosterone were increased. Mean arterial pressure, glomerular filtration rate (GFR), and fractional lithium excretion were decreased. Acute vasopressin type 2-receptor blockade with the selective nonpeptide antagonist OPC-31260 (800 microg. kg(-1). h(-1)) was performed during conditions whereby volume depletion was prevented by computer-driven, servo-controlled intravenous volume replacement with 150 mM glucose. The aquaretic response to OPC-31260 was similar in cirrhotic and control rats. However, the OPC 31260-induced rises in fractional water excretion (delta V/GFR; +24%) and fractional distal water excretion (delta V/C(Li); +46%) were significantly increased in the cirrhotic rats, where V is flow rate and delta is change. This suggests that vasopressin-mediated renal water reabsorption capacity was increased in the cirrhotic rats. Semiquantitative immunoblotting revealed that the expression of the vasopressin-regulated water channel aquaporin-2 was unchanged in membrane fractions of both whole kidney and inner medulla from cirrhotic rats. Together, these results suggest a relative escape from vasopressin on collecting duct water reabsorption in rats with decompensated liver cirrhosis.

Chronic subdural hematoma: evaluation of the clinical significance of postoperative drainage volume

OBJECT

A wide variation in postoperative drainage volumes is observed during treatment of chronic subdural hematoma (CSDH) with twist-drill or burr-hole craniostomy and closed-system drainage. In this study the authors investigate the causes of the variation, the clinical significance thereof, and its influence on treatment outcome.

METHODS

A total of 175 cases were investigated between January 1991 and December 1997. Of these, 145 patients had surgery for CSDH, of whom 30 had bilateral lesions. The cases of CSDH were divided into five subtypes (low-density, isodense, high-density, mixed-density, and layering types) on the basis of the brain computerized tomography (CT) findings. Burr-hole craniostomies with closed-system drainage were performed in all patients and the drainage was maintained for 5 days, during which daily amounts of fluid were measured. The mean drainage volume over 5 days was 320 ml, with the largest volume (413 ml) seen in the low-density type and the smallest (151 ml) in the mixed-density type of CSDH. There were recurrences in six patients (seven instances, 4%). The mixed-density type had the highest recurrence rate (8.6%), whereas there was no recurrence for the low-density type. There were no recurrences in 81 patients in whom the total drainage volumes for 5 days were more than 200 ml, but there were recurrences in six (seven instances) of 94 patients in whom the total drainage volume was less than 200 ml.

CONCLUSIONS

The postoperative drainage volumes varied greatly because of differences in the outer membrane permeability of CSDH, and such variation seems to be related to the findings on the CT scans obtained preoperatively. Patients with CSDH in whom there is less postoperative drainage than expected should be carefully observed, with special attention paid to the possibility of recurrence.

Immunolocalization of electroneutral Na-HCO(3)(-) cotransporter in rat kidney

An electroneutral Na-HCO(3)(-) cotransporter (NBC(N)1) was recently cloned, and Northern blot analyses indicated its expression in rat kidney. In this study, we determined the cellular and subcellular localization of NBC(N)1 in the rat kidney at the light and electron microscopic level. A peptide-derived antibody was raised against the COOH-terminal amino acids of NBC(N)1. The affinity-purified antibody specifically recognized one band, approximately 180 kDa, in rat kidney membranes. Peptide-N-glycosidase F deglycosylation reduced the band to approximately 140 kDa. Immunoblotting of membrane fractions from different kidney regions demonstrated strong signals in the inner stripe of the outer medulla (ISOM), weaker signals in the outer stripe of the outer medulla and inner medulla, and no labeling in cortex. Immunocytochemistry demonstrated that NBC(N)1 immunolabeling was exclusively observed in the basolateral domains of thick ascending limb (TAL) cells in the outer medulla (strongest in ISOM) but not in the cortex. In addition, collecting duct intercalated cells in the ISOM and in the inner medulla also exhibited NBC(N)1 immunolabeling. Immunoelectron microscopy demonstrated that NBC(N)1 labeling was confined to the basolateral plasma membranes of TAL and collecting duct type A intercalated cells. Immunolabeling controls were negative. By using 2, 7-bis-carboxyethyl-5,6-caboxyfluorescein, intracellular pH transients were measured in kidney slices from ISOM and from mid-inner medulla. The results revealed DIDS-sensitive, Na- and HCO(3)(-)-dependent net acid extrusion only in the ISOM but not in mid-inner medulla, which is consistent with the immunolocalization of NBC(N)1. The localization of NBC(N)1 in medullary TAL cells and medullary collecting duct intercalated cells suggests that NBC(N)1 may be important for electroneutral basolateral HCO(3)(-) transport in these cells.

Localization of aquaporin-7 in rat and mouse kidney using RT-PCR, immunoblotting, and immunocytochemistry

To establish the segmental, cellular, and subcellular localization of AQP7 in rat and mouse kidney, we used RT-PCR, immunocytochemical, and immunoblotting approaches. RT-PCR of rat and mouse kidney zones revealed AQP7 mRNA in cortex and outer stripe of the outer medulla. RT-PCR on microdissected nephron segments revealed AQP7 mRNA in proximal convoluted and straight tubules. Immunoblotting using peptide-derived rabbit antibodies to either rat or mouse AQP7 revealed a 28-kDa band in kidney and testes from rat and mouse, respectively. Immunocytochemistry revealed strong AQP7 labeling of segment 3 proximal tubules and weaker labeling of proximal convoluted tubules in both rat and mouse kidneys. The labeling was almost exclusively confined to the brush border with no basolateral labeling. No labeling was observed of thin descending limbs or collecting duct. Immunolabeling controls were negative. The presence of AQP7 in the proximal tubule brush border indicates a role of AQP7 in proximal tubule water reabsorption.

A masquerade-like serine proteinase homologue is necessary for phenoloxidase activity in the coleopteran insect, Holotrichia diomphalia larvae

Previously, we reported the molecular cloning of cDNA for the prophenoloxidase activating factor-I (PPAF-I) that encoded a member of the serine proteinase group with a disulfide-knotted motif at the N-terminus and a trypsin-like catalytic domain at the C-terminus [Lee, S.Y., Cho, M.Y., Hyun, J.H., Lee, K.M., Homma, K.I., Natori, S. , Kawabata, S.I., Iwanaga, S. & Lee, B.L. (1998) Eur. J. Biochem. 257, 615-621]. PPAF-I is directly involved in the activation of pro-phenoloxidase (pro-PO) by limited proteolysis and the overall structure is highly similar to that of Drosophila easter serine protease, an essential serine protease zymogen for pattern formation in normal embryonic development. Here, we report purification and molecular cloning of cDNA for another 45-kDa novel PPAF from the hemocyte lysate of Holotrichia diomphalia larvae. The gene encodes a serine proteinase homologue consisting of 415 amino-acid residues with a molecular mass of 45 256 Da. The overall structure of the 45-kDa protein is similar to that of masquerade, a serine proteinase homologue expressed during embryogenesis, larval, and pupal development in Drosophila melanogaster. The 45-kDa protein contained a trypsin-like serine proteinase domain at the C-terminus, except for the substitution of Ser of the active site triad to Gly and had a disulfide-knotted domain at the N-terminus. A highly similar 45-kDa serine proteinase homologue was also cloned from the larval cDNA library of another coleopteran, Tenebrio molitor. By in vitro reconstitution experiments, we found that the purified 45-kDa serine proteinase homologue, the purified active PPAF-I and the purified pro-PO were necessary for expressing phenoloxidase activity in the Holotrichia pro-PO system. However, incubation of pro-PO with either PPAF-I or 45-kDa protein, no phenoloxidase activity was observed. Interestingly, when the 45-kDa protein was incubated with PPAF-I and pro-PO in the absence, but not in the presence of Ca2+, the 45-kDa protein was cleaved to a 35-kDa protein. RNA blot hybridization revealed that expression of the 45-kDa protein was increased in the Holotrichia hemolymph after Escherichia coli challenge.

Immunolocalization of NBC3 and NHE3 in the rat epididymis: colocalization of NBC3 and the vacuolar H+-ATPase

In the male reproductive tract, the epididymis plays an important role in mediating transepithelial bicarbonate transport and luminal acidification. In the proximal vas deferens, a significant component of luminal acidification is Na+-independent, and mediated by specific cells that possess apical vacuolar proton pumps. In contrast, luminal acidification in the cauda epididymidis is an Na+-dependent process. The specific apical Na+-dependent H+/base transport process(es) responsible for luminal acidification have not been identified. A potential clue as to the identity of these apical Na+-dependent H+/base transporter(s) is provided by similarities between the transport properties of the epididymis and the mammalian nephron. Specifically, the H+/base transport properties of caput epididymidis resemble the mammalian renal proximal tubule, whereas the distal epididymis and vas deferens have characteristics in common with renal collecting duct intercalated cells. Given the known expression of the Na+/H+ antiporter, NHE3, in the proximal tubule, and of the electroneutral sodium bicarbonate cotransporter, NBC3, in renal intercalated cells, we determined the localization of NHE3 and NBC3 in various regions of rat epididymis. NBC3 was highly expressed on the apical membrane of apical (narrow) cells in caput epididymidis, and light (clear) cells in corpus and cauda epididymidis. The number of cells expressing apical NBC3 was highest in cauda epididymidis. The localization of NBC3 in the epididymis was identical to the vacuolar H+-ATPase. The results indicate that colocalization of NBC3 and the vacuolar H+-ATPase is not restricted to kidney intercalated cells. Moreover, the close association of the two transporters appears to be a more generalized phenomenon in cells that express high levels of vacuolar H+-ATPase. Unlike NBC3, NHE3 was most highly expressed on the apical membrane of all epithelial cells in caput epididymidis, with less expression in the corpus, and no expression in the cauda. These results suggest that apical NBC3 and NHE3 potentially play an important role in mediating luminal H+/base transport in epididymis.

Altered expression of renal AQPs and Na(+) transporters in rats with lithium-induced NDI

Lithium (Li) treatment is often associated with nephrogenic diabetes insipidus (NDI). The changes in whole kidney expression of aquaporin-1 (AQP1), -2, and -3 as well as Na-K-ATPase, type 3 Na/H exchanger (NHE3), type 2 Na-Pi cotransporter (NaPi-2), type 1 bumetanide-sensitive Na-K-2Cl cotransporter (BSC-1), and thiazide-sensitive Na-Cl cotransporter (TSC) were examined in rats treated with Li orally for 4 wk: protocol 1, high doses of Li (high Na(+) intake), and protocol 2, low doses of Li (identical food and normal Na(+) intake in Li-treated and control rats). Both protocols resulted in severe polyuria. Semiquantitative immunoblotting revealed that whole kidney abundance of AQP2 was dramatically reduced to 6% (protocol 1) and 27% (protocol 2) of control levels. In contrast, the abundance of AQP1 was not decreased. Immunoelectron microscopy confirmed the dramatic downregulation of AQP2 and AQP3, whereas AQP4 labeling was not reduced. Li-treated rats had a marked increase in urinary Na(+) excretion in both protocols. However, the expression of several major Na(+) transporters in the proximal tubule, loop of Henle, and distal convoluted tubule was unchanged in protocol 2, whereas in protocol 1 significantly increased NHE3 and BSC-1 expression or reduced NaPi-2 expression was associated with chronic Li treatment. In conclusion, severe downregulation of AQP2 and AQP3 appears to be important for the development of Li-induced polyuria. In contrast, the increased or unchanged expression of NHE3, BSC-1, Na-K-ATPase, and TSC indicates that these Na(+) transporters do not participate in the development of Li-induced polyuria.

Vasopressin V(2)-receptor-dependent regulation of AQP2 expression in Brattleboro rats

The role of AVP-V(2) receptor (AVP-V(2)R)-dependent regulation of aquaporin-2 (AQP2) expression was evaluated in vasopressin-deficient Brattleboro (BB) rats. AQP2 levels were relatively high in BB rats (52 +/- 8% of levels in Wistar rats), and treatment with the AVP-V(2)R antagonist SR-121463A (0.8 mg/day) for 48 h was associated with 1) increased urine output (170 +/- 9%), 2), reduced AQP2 protein levels (42 +/- 10% in whole kidney and 53 +/- 8% in inner medulla), and 3) reduced AQP2 mRNA levels (36 +/- 7%). In addition, the levels of AQP2 phosphorylated in the protein kinase A (PKA) consensus site (Ser(256) of AQP2) was reduced to 3 +/- 1% of control levels. Lithium (Li) treatment of BB rats for 1 mo, known to reduce adenylyl cyclase (AC) activity, downregulated AQP2 protein levels (15 +/- 6%) and increased urine output (220%). Downregulation of AQP2 expression in response to SR-121463A or Li treatment indicates that AQP2 expression in BB rats depends in part on activation of AVP-V(2)Rs and that the signaling cascade(s) involves AC and hence cAMP. Complete water restriction of BB rats produced only a small increase in AQP2 mRNA (235 +/- 33%) and AQP2 protein (156 +/- 22%) levels. Immunoelectron microscopy confirmed the increase in AQP2 abundance but revealed no change in AQP2 apical plasma membrane labeling in response to thirsting. In conclusion, the expression and phosphorylation of AQP2 in BB rats are in part dependent on AVP-V(2)R signaling, and AVP-V(2)-mediated regulation of AQP2 trafficking and expression is effectively decoupled in BB rats, indicating differences in AVP-V(2)R-mediated regulation of AQP2 trafficking and expression.

Inhibitory effects of methanol extract of seeds of Job's Tears (Coix lachryma-jobi L. var. ma-yuen) on nitric oxide and superoxide production in RAW 264.7 macrophages

Overproduction of nitric oxide (NO) or superoxide (O2-) by activated macrophages is known to be involved in acute or chronic inflammation. The seeds of Job's Tears (Coix lachryma-jobi L. var. ma-yuen) have been used as anti-inflammatory medicine and health food. However, it is still unclear how the seeds show anti-inflammatory properties. Using murine macrophage-like RAW 264.7 cells, we tried to know whether the overproduction of NO and O2 by activated macrophages could be prevented by the methanol (MeOH) extract of the seeds of Job's Tears. RAW 264.7 cells were activated with interferon-gamma plus lipopolysaccharide to produce NO and with pholbol ester to produce O2-. The MeOH extract showed marked inhibition of NO production by activated RAW 264.7 cells in a dose-dependent manner via suppression of inducible NO synthase mRNA expression. The MeOH extract also showed inhibition of O2- production by activated RAW 264.7 cells in dose- and time-dependent manners, possibly by interfering with NADPH oxidase machinery of macrophages. Collectively, these results demonstrate that the MeOH extract of the seeds of Job's Tears shows anti-inflammatory properties which may, in part, involve an inhibition of NO and O2- production by activated macrophages.

Expression of glucose oxidase by using recombinant yeast

The glucose oxidase gene (GO) of Aspergillus niger was cloned into the yeast shuttle vector YEp352 with combinations of various promoters and terminators, and then used to transform Saccharomyces cerevisiae. Expressed GO was successfully secreted into culture medium due to the presence of the intrinsic signal peptide of GO. Four different promoters fused to GO were tested: bidirectional galactose dehydrogenase 1 and 10 (GAL1, GAL10) promoters, glyceraldehyde-3-phosphate dehydrogenase (GPD) promoter and an yeast hybrid ADH2-GPD promoter consisting of alcohol dehydrogenase II (ADH2) and GPD promoter. The intrinsic terminator of GO as well as the GAL7 terminator were also compared for better production of GO. Deletion of most of the terminating region from GO yielded only a slight amount of GO while the presence of either terminator greatly increased GO production. The GAL10 promoter produced the least amount of GO, GAL1 and GPD promoters were moderate, and the ADH2-GPD hybrid promoter was the best among all tested. However, the hybrid promoter was tightly regulated by the presence of an excess amount of either glucose or ethanol, and it appeared that 2% glucose and 1. 5% ethanol supplement was the best concentration for GO production. It was possible to produce 260 IU ml(-1) of GO, an equivalent of 5 g l(-1), under the presence of 2% glucose and 1.5% ethanol. UV mutagenesis of a recombinant S. cerevisiae was also applied and it further increased the yield of GO to 460 IU ml(-1) under the presence of 2% glucose and 1.5% ethanol without any changes in cell growth. Corn steep liquor which is commonly used in bioindustry is a good alternative substrate for high priced glucose for the hybrid promoter and suggests a cost effective means for commercial mass production of GO using recombinant yeast.

Crystallization and preliminary X-Ray diffraction analysis of glutaryl-7-aminocephalosporanic acid acylase from Pseudomonas sp. GK16

Glutaryl-7-aminocephalosporanicacid acylase from Pseudomonas sp. GK16 produces glutaryl-7-aminocephalosporanic acid, a key intermediate for the synthesis of cephem antibiotics. Sequence alignment suggests that the enzyme may belong to the N-terminal nucleophile hydrolase superfamily including penicillin G acylase. The enzyme is an (alphabeta)(2) heterotetramer of two nonidentical subunits. These subunits are derived from a nascent precursor polypeptide that is cleaved proteolytically through a two-step autocatalytic process upon folding. The enzyme has been crystallized using the vapor diffusion method. A bipyramidal crystal form was obtained from a solution containing polyethylene glycol (MW 3350) and calcium chloride. Complete diffraction data sets have been collected up to 2.8 A resolution. The crystal is tetragonal with the space group P4(1)2(1)2 or P4(3)2(1)2 and the unit cell parameters are a = b = 73.5 A, c = 380.3 A. Considerations of the possible values of V(m) account for the presence of a tetramer in the asymmetric unit.

Decreased abundance of major Na(+) transporters in kidneys of rats with ischemia-induced acute renal failure

Ischemia-induced acute renal failure (ARF) is known to be associated with significant impairment of tubular Na reabsorption. We examined whether temporary bilateral renal ischemia (30, 40, or 60 min) and reperfusion (1-5 days) affect the abundance of several renal Na transporters and urinary Na excretion (U(Na)V) in rats. In rats with mild ARF (30 min), immunoblotting revealed that proximal tubule type 3 Na(+)/H(+) exchanger (NHE-3) and type II Na-P(i) cotransporter (NaPi-II) were significantly decreased to 28 +/- 6 and 14 +/- 6% of sham levels, respectively, at day 1. Moreover, Na(+)-K(+)-ATPase levels were also significantly decreased (51 +/- 11%), whereas there was no significant decrease in type 1 bumetanide-sensitive cotransporter (BSC-1) and thiazide-sensitive cotransporter (TSC) levels. Consistent with reduced Na transporter abundance, fractional urinary Na excretion (FE(Na)) was significantly increased in mild ARF (30 min) and U(Na)V was unchanged, despite a marked reduction in glomerular filtration rate. Na transporter levels and renal Na handling were normalized within 5 days. Severe ischemic injury (60 min) resulted in a marked decrease in the abundance of Na(+)-K(+)-ATPase, NHE-3, NaPi-II, BSC-1, and TSC at both days 1 and 5. Consistent with this, FE(Na) was significantly increased at days 1 and 5. Intravenous K-melanocyte-stimulated hormone treatment partially prevented the ischemia-induced downregulation of renal Na transporters and reduced the high FE(Na) to control levels. We conclude that reduced levels of Na transporters along the nephron may play a critical role in the impairment of tubular Na reabsorption, and hence increased Na excretion, in ischemia-induced ARF.

Activated phenoloxidase from Tenebrio molitor larvae enhances the synthesis of melanin by using a vitellogenin-like protein in the presence of dopamine

One of the biological functions of activated phenoloxidase in arthropods is the synthesis of melanin around invaded foreign materials. However, little is known about how activated phenoloxidase synthesizes melanin at the molecular level. Even though it has been suggested that the quinone derivatives generated by activated phenoloxidase might use endogenous protein components for melanin synthesis in arthropods, there is no report of protein components engaged in melanin synthesis induced by activated phenoloxidase. In this study, to isolate and characterize proteins involved in melanin synthesis, we prepared in vitro prophenoloxidase activating solution (designated G-100 solution), specifically showing phenoloxidase activity in the presence of Ca2+ and beta-1, 3-glucan, from the hemolymph of larvae of the coleopteran Tenebrio molitor by using a Sephadex G-100 column. When G-100 solution was incubated with dopamine to induce melanin synthesis in the presence of Ca2+ and beta-1,3-glucan, four types of protein (160 kDa, prophenoloxidase, phenoloxidase and 45 kDa) disappeared from SDS/PAGE under reducing conditions. Under identical conditions, but including phenylthiourea as a phenoloxidase inhibitor added to the G-100 solution, three of these proteins (160 kDa, phenoloxidase and 45 kDa) did not disappear. To characterize these melanization-engaging proteins, we first purified the 160-kDa melanization-engaging protein to homogeneity and raised a polyclonal antibody against it. Analysis of the cDNA revealed that it consisted of 1439 amino-acid residues and showed partial homology with Caenorhabditis elegans vitellogenin precursor-6 (19.7%). Western blot analysis showed that it disappeared when active phenoloxidase induced melanin synthesis. Furthermore, when the purified 160-kDa melanization-engaging protein was added to a G-100 solution deficient in it, melanin synthesis was enhanced compared with the same solution without the protein. These data support the conclusion that the 160-kDa vitellogenin-like protein is involved in arthropod melanin synthesis.

Bacterial-injection-induced syntheses of N-beta-alanyldopamine and Dopa decarboxylase in the hemolymph of coleopteran insect, Tenebrio molitor larvae

Injection of Escherichia coli into larvae of the coleopteran Tenebrio molitor resulted in the appearance of a dopamine-like substance on the electrochemical detector. To characterize this dopamine-like substance, we purified it to homogeneity from the immunized hemolymph and determined its molecular structure to be N-beta-alanyldopamine using the liquid chromatographic/tandem mass spectrometric method. Chemically synthesized N-beta-alanyldopamine showed the same retention time on HPLC as the purified N-beta-alanyldopamine from immunized larvae. To elucidate the molecular mechanism of N-beta-alanyldopamine synthesis in vivo, we examined the enzyme activity of Dopa decarboxylase against E. coli-injected hemolymph of T. molitor larvae. The enzyme activity of Dopa decarboxylase increased dramatically approximately 8 h after injection; Dopa decarboxylase activity of injected larvae being 10-times higher than naive larvae after 24 h. To evaluate the extent of quantitative changes of Dopa decarboxylase in response to bacterial challenge, Tenebrio Dopa decarboxylase was purified to homogeneity from the whole larvae and a cDNA clone for Tenebrio Dopa decarboxylase was isolated. RNA blot hybridization revealed that expression of the Dopa decarboxylase gene was activated transiently 3-8 h after E. coli challenge. Immunoprecipitation experiments showed that Tenebrio Dopa decarboxylase was detected from 8 to 24 h in E. coli-injected larval extract. Thus, bacterial injection into T. molitor larvae might induce transcriptional activation of a Dopa decarboxylase gene, and then synthesis of N-beta-alanyldopamine. The synthesized N-beta-alanyldopamine might be used as a substrate by phenoloxidase during melanin synthesis in the humoral defense response or the melanotic encapsulation reaction of the cellular defense response.

Immunoelectron microscopic localization of NBC3 sodium-bicarbonate cotransporter in rat kidney

In the present study, we produced a rabbit peptide-derived polyclonal COOH-terminal antibody that selectively recognizes NBC3, to determine the cellular and subcellular localization of NBC3 in rat kidney, using immunocytochemistry and immunoelectron microscopy. Immunocytochemistry with cryostat sections and semithin cryosections revealed specific staining of intercalated cells (ICs) in the connecting tubule and in cortical, outer medullary, and initial inner medullary collecting ducts. In the connecting tubule and in the cortical and medullary collecting duct, the labeling was associated with both type A and type B ICs. In type A ICs, labeling was confined to the apical and subapical domains, whereas in type B ICs, basal domains were exclusively labeled. In contrast, collecting duct principal cells were consistently unlabeled, and this was confirmed using anti-aquaporin-2 antibodies, which labeled principal cells in parallel semithin cryosections. Glomeruli, proximal tubules, descending thin limbs, ascending thin limbs, thick ascending limbs, distal convoluted tubules, and vascular structures were unlabeled. For immunoelectron microscopy, tissue samples were freeze-substituted, and immunolabeling was performed on ultrathin Lowicryl HM20 sections. Immunoelectron microscopy demonstrated that NBC3 labeling was very abundant in the apical plasma membrane, in intracellular vesicles, and in tubulocisternal profiles in the subapical domains of type A ICs. In type B ICs, NBC3 was mainly present in the basolateral plasma membrane. Immunolabeling controls using peptide-absorbed antibody were consistently negative. In conclusion, NBC3 is highly abundant in the apical plasma membrane of type A ICs and in the basolateral plasma membrane of type B ICs. This suggests that NBC3 plays an important role in modulating bicarbonate transport in the connecting tubule and collecting duct.

NBC3 expression in rabbit collecting duct: colocalization with vacuolar H+-ATPase

We have recently cloned and characterized a unique sodium bicarbonate cotransporter, NBC3, which unlike other members of the NBC family, is ethylisopropylamiloride (EIPA) inhibitable, DIDS insensitive, and electroneutral (A. Pushkin, N. Abuladze, I. Lee, D. Newman, J. Hwang, and I. Kurtz. J. Biol. Chem. 274: 16569-16575, 1999). In the present study, a specific polyclonal antipeptide COOH-terminal antibody, NBC3-C1, was generated and used to determine the pattern of NBC3 protein expression in rabbit kidney. A major band of approximately 200 kDa was detected on immunoblots of rabbit kidney. Immunocytochemistry of rabbit kidney frozen sections revealed specific staining of the apical membrane of intercalated cells in both the cortical and outer medullary collecting ducts. The pattern of NBC3 protein expression in the collecting duct was nearly identical to the same sections stained with an antibody against the vacuolar H+-ATPase 31-kDa subunit. In addition, the NBC3-C1 antibody coimmunoprecipitated the vacuolar H+-ATPase 31-kDa subunit. Functional studies in outer medullary collecting ducts (inner stripe) showed that type A intercalated cells have an apical Na+-dependent base transporter that is EIPA inhibitable and DIDS insensitive. The data suggest that NBC3 participates in H+/base transport in the collecting duct. The close association of NBC3 and the vacuolar H+-ATPase in type A intercalated cells suggests a potential structural/functional interaction between the two transporters.

Cellular and subcellular immunolocalization of ClC-5 channel in mouse kidney: colocalization with H+-ATPase

To determine the immunolocalization of ClC-5 in the mouse kidney, we developed a ClC-5-specific rat monoclonal antibody. Immunoblotting demonstrated an 85-kDa band of ClC-5 in the kidney and ClC-5 transfected cells. Immunocytochemistry revealed significant labeling of ClC-5 in brush-border membrane and subapical intracellular vesicles of the proximal tubule. In addition, apical and cytoplasmic staining was observed in the type A intercalated cells in the cortical collecting duct. In contrast, the staining was minimal in the outer and inner medullary collecting ducts and the thick ascending limb. Western blotting of vesicles immunoisolated by the ClC-5 antibody showed the presence of H+-ATPase, strongly indicating that these two proteins were present in the same membranes. Double labeling with antibodies against ClC-5 and H+-ATPase and analysis by confocal images showed that ClC-5 and H+-ATPase colocalized in these ClC-5-positive cells. These findings suggest that ClC-5 might be involved in the endocytosis and/or the H+ secretion in the proximal tubule cells and the cortical collecting duct type A intercalated cells in mouse kidney.

Rapid gating and anion permeability of an intracellular aquaporin

Aquaporin (AQP) water-channel proteins are freely permeated by water but not by ions or charged solutes. Although mammalian aquaporins were believed to be located in plasma membranes, rat AQP6 is restricted to intracellular vesicles in renal epithelia. Here we show that AQP6 is functionally distinct from other known aquaporins. When expressed in Xenopus laevis oocytes, AQP6 exhibits low basal water permeability; however, when treated with the known water channel inhibitor, Hg2+, the water permeability of AQP6 oocytes rapidly rises up to tenfold and is accompanied by ion conductance. AQP6 colocalizes with H+-ATPase in intracellular vesicles of acid-secreting alpha-intercalated cells in renal collecting duct. At pH less than 5.5, anion conductance is rapidly and reversibly activated in AQP6 oocytes. Site-directed mutation of lysine to glutamate at position 72 in the cytoplasmic mouth of the pore changes the cation/anion selectivity, but leaves low pH activation intact. Our results demonstrate unusual biophysical properties of an aquaporin, and indicate that anion-channel function may now be explored in a protein with known structure.

Reduced abundance of aquaporins in rats with bilateral ischemia-induced acute renal failure: prevention by alpha-MSH

We examined the effect of temporary renal ischemia (30 min or 60 min) and reperfusion (1 day or 5 days) on the expression of renal aquaporins (AQPs) and urinary concentration in rats with bilateral ischemia-induced acute renal failure (ARF). Next, we tested whether reducing ischemia/reperfusion (I/R) injury by treatment with alpha-melanocyte stimulating hormone (alpha-MSH) affects the expression of AQPs and urine output. Rats with ARF showed significant renal insufficiency, and urinary concentration was markedly impaired. In rats with mild ischemic injury (30 min), urine output increased significantly to a maximum at 48 h, and then nearly normalized within 5 days. Consistent with this, semiquantitative immunoblotting revealed that kidney AQP1 and AQP2 abundance was significantly decreased after 24 h to 30 +/- 5% and 40 +/- 11% (n = 8) of controls (n = 9), respectively (P < 0.05). Five days after ischemia, AQP2 abundance was not significantly decreased and urine output was normalized. In contrast, severe ischemic injury (60 min) resulted in a marked reduction in urine output at 24 h, despite a significant decrease in urine osmolality and solute-free water reabsorption, T(c)H(2)O. AQP1 and AQP2 abundance was markedly decreased to 51 +/- 5% and 31 +/- 9% (n = 10) of controls (n = 8) at 24 h (P < 0.05). After 5 days, the rats developed gradually severe polyuria and had very low AQP2 and AQP1 levels [11 +/- 4% and 6 +/- 2% (n = 5) of controls (n = 8), respectively; P < 0.05]. A similar reduction was observed for AQP3. The reduction in AQP expression in the proximal tubule and inner medullary collecting duct was confirmed by immunocytochemistry. Next, we found that intravenous alpha-MSH treatment of rats with ARF significantly reduced the ischemia-induced downregulation of renal AQPs and reduced the polyuria. In conclusion, the I/R injury is associated with markedly reduced expression of the collecting duct and proximal tubule AQPs, in association with an impairment of urinary concentration. Moreover, alpha-MSH treatment significantly prevented the reduction in expression of AQPs and renal functional defects. Thus decreased AQP expression is likely to contribute to the impairment in urinary concentration in the postischemic period.

Altered expression of Na transporters NHE-3, NaPi-II, Na-K-ATPase, BSC-1, and TSC in CRF rat kidneys

In chronic renal failure (CRF), reduction in renal mass leads to an increase in the filtration rates of the remaining nephrons and increased excretion of sodium per nephron. To address the mechanisms involved in the increased sodium excretion, we determined the total kidney levels and the densities per nephron of the major renal NaCl transporters in rats with experimental CRF. Two weeks after 5/6 nephrectomy (reducing the total number of nephrons to approximately 24 +/- 8%), the rats were azotemic and displayed increased Na excretion. Semiquantitative immunoblotting revealed significant reduction in the total kidney levels of the proximal tubule Na transporters NHE-3 (48% of control), NaPi-II (13%), and Na-K-ATPase (30%). However, the densities per nephron of NHE-3, NaPi-II, and Na-K-ATPase were not significantly altered in remnant kidneys, despite the extensive hypertrophy of remaining nephrons. Immunocytochemistry confirmed the reduction in NHE-3 and Na-K-ATPase labeling densities in the proximal tubule. In contrast, there was no significant reduction in the total kidney levels of the thick ascending limb and distal convoluted tubule NaCl transporters BSC-1 and TSC, respectively. This corresponded to a 3.6 and 2.5-fold increase in densities per nephron, respectively (confirmed by immunocytochemistry). In conclusion, in this rat CRF model: 1) increased fractional sodium excretion is associated with altered expression of proximal tubule Na transporter expression (NHE-3, NaPi-II, and Na-K-ATPase), consistent with glomerulotubular imbalance in the face of increased single-nephron glomerular filtration rate; and 2) compensatory increases in BSC-1 and TSC expression per nephron occur in distal segments.

Decreased abundance of collecting duct aquaporins in post-ischemic renal failure in rats

Increased urine flow is often a feature of mild to moderate acute renal failure. This study examines the possible role of dysregulation of collecting duct aquaporins as a factor in this increase. In rats, the left renal pedicle was clamped for 45 min followed by contralateral nephrectomy. Control rats were identical except that the renal pedicle was not clamped. Rats were sacrificed and the kidneys were homogenized at various time points after release of the clamp for semiquantitative immunoblotting of collecting duct aquaporins, as well as the thick ascending limb Na-K-2Cl cotransporter and the proximal tubule water channel, aquaporin-1. Urinary flow rate was significantly increased 18 h after the ischemic insult and remained increased through 72 h. Whole kidney aquaporin-2 protein abundance was 45% of controls at 18 h, 55% of controls at 36 h, and returned to normal 72 h after ischemia. Whole kidney aquaporin-3 protein abundance was 37% of controls at 18 h, 13% of controls at 36 h, and 45% of controls at 72 h. The decline in aquaporin-2 and -3 was confirmed by immunocytochemistry. Abundance of the thick ascending limb Na-K-2Cl cotransporter protein was not significantly decreased. Aquaporin-1 protein abundance was not significantly decreased at 18 h after the ischemic insult, but was significantly reduced after 36 h. Thus, the post-ischemic state is associated with decreased levels of the collecting duct aquaporins, coinciding with an increase in water excretion. It is concluded that decreased aquaporin protein abundance in collecting duct cells is a contributing factor in the increased urine flow seen in moderate post-ischernic acute renal failure.