Interaction mechanisms between autophagy and ferroptosis: Potential role in colorectal cancer

Colorectal cancer (CRC) is a common malignancy that has the second highest incidence and mortality rate. Although there are many personalized treatment options for CRC, the therapeutic effects are ultimately limited by drug resistance. Studies have aimed to block the initiation and progression of CRC by inducing cell death to overcome this obstacle. Substantial evidence has indicated that both autophagy and ferroptosis play important regulatory roles in CRC. Autophagy, a lysosome-dependent process by which cellular proteins and organelles are degraded, is the basic mechanism for maintaining cell homeostasis. The duality and complexity of autophagy in cancer therapy is a hot topic of discussion. Ferroptosis, a regulated cell death pathway, is associated with iron accumulation-induced lipid peroxidation. The activation of ferroptosis can suppress CRC proliferation, invasion and drug resistance. Furthermore, recent studies have suggested an interaction between autophagy and ferroptosis. Autophagy can selectively degrade certain cellular contents to provide raw materials for ferroptosis, ultimately achieving antitumor and anti-drug resistance. Therefore, exploring the interaction between autophagy and ferroptosis could reveal novel ideas for the treatment of CRC. In this review, we describe the mechanisms of autophagy and ferroptosis, focusing on their roles in CRC and the crosstalk between them.

[The clinical characteristics of functional hypothalamic amenorrhea with hyperandrogenism]

Objective: To explore the clinical and biochemical discriminants of hyperandrogenism in functional hypothalamic amenorrhea (FHA). Methods: From January to September 2022, a total of 56 patients with FHA group in the Obstetrics and Gynecology Hospital of Fudan University outpatient clinic were included in this retrospective cross-sectional analysis. According to the clinical or biochemical features of hyperandrogenism, FHA patients can be divided into two subgroups, namely hyperandrogenic FHA and non-hyperandrogenic FHA. Explore the differences and its significances between hyperandrogenic FHA and non-hyperandrogenic FHA by comparing anthropometry, reproductive hormones, AMH, ultrasonic manifestation, the scores of eating attitude test, depression questionnaire and anxiety scale respectively and analyzing their correlations. Results: The age of 56 FHA patients was 15-32(23.36±4.90) years, and body mass index(BMI) was (18.91±2.49) kg/m². The age of hyperandrogenic FHA and non-hyperandrogenic FHA was (21.76±4.40) and (24.05±5.00) (P=0.109) years old respectively, and BMI was (19.14±3.15 )and (18.81±2.18) kg/m² (P=0.702). Compared to the non-hyperandrogenic FHA, the AMH (6.46 and 3.63 ng/ml, P=0.025) and PRL (278.78 and 149.46 mU/ml, P=0.002) levels were higher in hyperandrogenic FHA group. There was no significant difference between the hyperandrogenic and non-hyperandrogenic FHA group in body composition.GAD-7 (r=0.455, P=0.005) and PHQ-9 (r=0.664, P<0.001) were correlated with EAT-26 scores in non-hyperandrogenic FHA group, but no significant correlation was shown between PHQ-9 (r=0.091, P=0.766)、GAD-7 (r=0.304, P=0.313) and EAT-26 in hyperandrogenic FHA group. Conclusions: Some patients with FHA had clinical manifestations of hyperandrogenism and mildly elevated AMH and PRL, with underlying PCOS endocrine characteristics.

SphK1-driven autophagy potentiates focal adhesion paxillin-mediated metastasis in colorectal cancer

Invasion and metastasis are the main causes of colorectal cancer (CRC)‐related death. Accumulating evidence suggested that sphingosine kinase 1 (SphK1) promoted the metastasis of CRC and autophagy played an important role in SphK1 promoting the metastasis of malignancy. However, the mechanism by which SphK1‐driven autophagy promotes invasion and metastasis in CRC remains to be clarified. In the present study, immunohistochemical detection showed the expression of SphK1 and paxillin was higher in human CRC tissues than those of normal colorectal mucosal tissues, they were both associated with TNM staging, lymphatic, and distance metastasis. In addition, study of in situ tumor transplantation model in nude mice showed that the suppression of SphK1 inhibited the growth of colonic orthotopic implantation tumors and the expression of paxillin, p‐paxillin, LC3 in the tumor. So, SphK1 may promote CRC metastasis via inducing the expression of paxillin expression and its phosphorylation, in vivo. Furthermore, results of CCK8 assay, transwell and wound healing assays showed that SphK1 promoted the viability, invasion, and metastasis of CRC cells. Transmission electron microscopy detection showed that SphK1 is the key factor in autophagy induction in CRC cells. Moreover, western blot examination indicated that the expression of LC3Ⅱ/Ⅰ, paxillin, p‐paxillin, MMP‐2, and vimentin was enhanced in SphK1‐overexpressed CRC cells and suppressed in SphK1 knockdown CRC cells, meanwhile, the expression of E‐cadherin was suppressed in SphK1‐overexpressed CRC cells and enhanced in SphK1 knockdown CRC cells. Suppression of autophagy by 3MA reversed the expression of paxillin and its phosphorylation in SphK1‐overexpressed CRC cells, indicated that SphK1‐driven autophagy induced the expression of paxillin and its phosphorylation in CRC cells. Together, these findings reveal that SphK1‐driven autophagy may promote the invasion and metastasis of CRC via promoting the expression of focal adhesion paxillin and its phosphorylation.

The Function of Wnt Ligands on Osteocyte and Bone Remodeling

Bone homeostasis is continually maintained by the process of bone remodeling throughout life. Recent studies have demonstrated that Wnt signaling pathways play a fundamental role in the process of bone homeostasis and remodeling. Intracellular Wnt signaling cascades are initially triggered by a Wnt ligand-receptor complex formation. In previous studies, the blocking of Wnt ligands from different osteoblastic differentiation stages could cause defective bone development at an early stage. Osteocytes, the most abundant and long-lived type of bone cell, are a crucial orchestrator of bone remodeling. However, the role of Wnt ligands on osteocyte and bone remodeling remains unclear. In our present study, we found that, besides osteoblasts, osteocytes also express multiple Wnt ligands in the bone environment. Then, we used a Dmp1-Cre mouse line, in which there is expression in a subset of osteoblasts but mainly osteocytes, to study the function of Wnt ligands on osteocyte and bone remodeling in vivo. Furthermore, we explored the role of Wnt ligands on osteocytic mineralization ability, as well as the regulatory function of osteocytes on the process of osteoblastic differentiation and osteoclastic migration and maturity in vitro. We concluded that Wnt proteins play an important regulatory role in 1) the process of perilacunar/canalicular remodeling, as mediated by osteocytes, and 2) the balance of osteogenesis and bone resorption at the bone surface, as mediated by osteoblasts and osteoclasts, at least partly through the canonical Wnt/β-catenin signaling pathway and the OPG/RANKL signaling pathway.

[Correlation analysis between Dx-pH monitoring and proton pump inhibitor test in the diagnosis of laryngopharyngeal reflux disease]

Objective: The consistency of 24-hour oropharyngeal Dx-pH monitoring and proton pump inhibitor(PPI) test in the diagnosis of laryngopharyngeal reflux disease (LPRD) was investigated. Methods: Sixty patients with laryngopharyngeal reflux (LPR) related symptoms who had never received PPI treatment were assessed by reflux symptom index (RSI) and reflux finding score (RFS) between October 2017 and October 2018, including 28 males and 38 females, aged from 16 to 72 years, with a medium age of 38 years. Prior to treatment, all patients were evaluated with 24 hours oropharyngeal Dx-pH monitoring(Restech). After empiric therapy with PPI twice-daily for 8 weeks, the efficacy was evaluated according to posttreatment RSI score.The data was analysed with Kruskal-Wallis test, Student Newman Keuls test and consistency check. Results: (1)Among all 60 patients,13 patients (21.7%) had pathologic Ryan score and all resulted responsive to PPI;27 patients (45.0%) with a negative Ryan score were unresponsive to PPI; 20 patients (33.3%) despite a negative Ryan score resulted responsive to PPI therapy. Considering responsiveness to PPI therapy as the gold standard for the diagnosis of LPRD, the sensitivity, specificity, positive predictive value and negative predictive value of Ryan score were 39.4%, 100%, 100% and 57.4% respectively. The Kappa value was 0.369 (P<0.01). (2)Among 34 patients (56.7%) with positive Dx-pH results (24-hour oropharyngeal acid reflux events≥ 3 times), 29 patients were positive and 5 patients were negative in PPI test. Among 26 patients with negative Dx-pH results (24-hour oropharyngeal acid reflux events<3 times), 4 patients were positive and 22 patients were negative in PPI test. Considering responsiveness to PPI therapy as the gold standard for the diagnosis of LPRD, the sensitivity, specificity, positive predictive value and negative predictive value of 24-hour oropharyngeal acid reflux events were 87.9%, 81.5%, 85.3% and 84.6% respectively. The Kappa value was 0.696(P<0.01). Conclusions: There is a positive correlation between 24-hour oropharyngeal Dx-pH monitoring positive results (24-hour oropharyngeal acid reflux events≥3 times) and PPI test in the diagnosis of LPRD. The 24-hour oropharyngeal Dx-pH monitoring can be a promising tool for the diagnosis of suspected LPRD patients, and more sensitive and accurate Dx-pH diagnostic index will be required in the clinic.

[Association between serum Nε-carboxymethyl-lysine level and anterior tibial arterial plaque calcification in patients with diabetic foot post foot amputation]

Objective: To observe the correlation between Nε-carboxymethyl-Lysine (CML), the main component of advanced glycation end products and the calcification of the anterior tibial artery plaque in patients with diabetic foot post foot amputation. Methods: Sixty patients hospitalized for foot amputation operation due to diabetic foot from June 2012 to June 2016 in the Department of Orthopedics, Affiliated Hospital of Jiangsu University were prospectively recruited.The patients were categorized into mild stenosis (0<stenosis<50%, n=20), moderate stenosis (50%≤stenosis<70%, n=20) and severe stenosis (70%≤stenosis≤100%, n=20) based on the color Doppler ultrasound assessed severity of anterior tibial artery stenosis.The baseline clinical data of patients were collected and anterior tibial artery was isolated.Then, HE staining, O-Cresolphthalein Complexone method, enzymic method and ELASA analysis were then performed to detect the evolution of calcification, arterial calcium content, alkaline phosphatase activity and serum CML concentration, respectively. Results: The results from both color Doppler ultrasound scan before amputation and HE staining after amputation showed that echo intensity as well as spotty blue calcium particles of anterior tibial artery plaque increased significantly in proportion to degree of stenosis and destructed elastic plate of the arterial wall was evidenced in patients with severest stenosis.The content of calcium ((2.3±0.9), (3.9±1.3), (6.6±1.7) μmol/mg, respectively, P<0.001), ALP activity ((102.4±39.4), (202.3±73.4), (483.7±117.9) U/mg, respectively, P<0.001) and serum CML level ((28.9±4.4), (37.9±5.3), (57.3±7.1)μg/L, respectively, P<0.001) increased significantly in proportion to stenosis severity.Pearson correlation analysis showed that serum CML level was positively correlated with the content of calcium (r=0.749, P<0.001) and ALP activity (r=0.923, P<0.001), respectively. Conclusions: Serum CML level is positively correlated with the calcification of anterior tibial arterial plaque in patients with diabetic foot and could be used to evaluate the calcification of anterior tibial arterial plaque and stenosis degree of anterior tibial arterial in these patients.

[Classification and corrective methods of obviously asymmetric palpebral fissure of single-fold eyelid]

OBJECTIVE

To discuss the classification of obviously asymmetric palpebral fissure of single-fold eyelid and their corrective methods performed with double-fold eyelid blepharoplasty simultaneously.

METHODS

Forty patients with obviously asymmetric palpebral fissure of single-fold eyelid of two eyes were admitted to Linyi People's Hospital in Shandong province from January 2010 to September 2014, asking for double-fold eyelid blepharoplasty. The preoperative difference of palpebral fissure width between two eyes reached 1.0-2.0 (1.44±0.23) mm. Obviously asymmetric palpebral fissures of single-fold eyelid were divided into three types according to the characteristics of eyelids of two eyes and were corrected by following methods performed with double-fold eyelid blepharoplasty with total incision simultaneously. (1) Twenty-four patients only with different sagging skin of upper eyelids were corrected by resecting sagging skin of eyelids' margins, and the width of the widest position of resected eyelids' skin was twice as wide as that of the sagging skin of eyelids' margins (the same below). (2) Among 6 patients only with different palpebral fissure width, 4 patients whose difference of palpebral fissure width was not bigger than 1.4 mm were corrected by the method of resecting surplus skin, and the width of the widest position of resected eyelids' skin with narrower palpebral fissure was 1 mm wider than the difference of palpebral fissure width between two eyes (the same below). The other 2 patients whose difference of palpebral fissure width between two eyes was bigger than 1.4 mm were corrected by the method of resecting surplus skin and shortening aponeurosis of levator muscle of upper eyelid. The width of shortened aponeurosis of levator muscle of eyelids with narrower palpebral fissure was 1 mm wider than difference of palpebral fissure width between two eyes (the same below). (3) Among 10 patients with mixing symptoms of sagging upper eyelids skin and difference of palpebral fissure width bigger than 1.0 mm after smoothing sagging upper eyelids' skin, 7 patients whose difference of palpebral fissure width was not bigger than 1.4 mm were corrected by resecting sagging skin and the method of resecting surplus skin. The other 3 patients whose difference of palpebral fissure width was bigger than 1.4 mm were corrected by resecting sagging skin, shortening aponeurosis of levator muscle of upper eyelids and resecting surplus skin. Palpebral fissure widths of patients were measured during follow-up. Difference of palpebral fissure width between two eyes was calculated and the last difference was recorded. Data were processed with paired sample t test.

RESULTS

Nine patients who showed incomplete closure of palpebral fissure on the sides of resected eyelids skin or shortened aponeurosis of levator muscle of upper eyelids after operations were treated with erythromycin eye ointment drop in eyes and recovered one week to one month after operations, with no complication of conjunctivitis or keratitis. Double-fold eyelids of all patients who were followed up for 8 to 12 months showed natural shape, smooth lines. No patient showed obvious asymmetry of palpebral fissure between two eyes, and no recurrence of asymmetric palpebral fissure was observed. Difference of palpebral fissure width was 0.1-0.5 (0.19±0.09) mm in the last follow-up, which was obviously smaller than that before operation (t=39.202, P<0.001).

CONCLUSIONS

Obviously asymmetric palpebral fissure of single-fold eyelid can be corrected during the operation of double-fold eyelid blepharoplasty. Patients only with different sagging skin of upper eyelids can be corrected by resecting sagging skin of eyelids' margins. Patients only with different palpebral fissure width between two eyes can be corrected by the method of resecting surplus skin or combining the method of shortening aponeurosis of levator muscle of upper eyelids. Patients with different sagging skin of upper eyelids and different palpebral fissure width can be corrected by resecting sagging skin of eyelids' margins and the method of resecting surplus skin or combining the method of shortening aponeurosis of levator muscle of upper eyelids.

Impact of the free-vaccine policy on timely initiation and completion of hepatitis B vaccination in Fujian, China

The extent to which the free-vaccine policy impacts the initiation and completion of a hepatitis B vaccine series is poorly understood. The aim of this study was to evaluate the impact of the free-vaccine policy on hepatitis B vaccination. A provincial survey was conducted in 2006 in Fujian Province, south-east of China, where the free-vaccine policy for hepatitis B was announced in 2002 and implemented in 2003. A total of 1628 children were investigated, and 1443 (88.6%) were included in this analysis. Among the children studied, 55.2% were vaccinated within 24 h of birth, and 76.1% completed the hepatitis B vaccine series on time. The rate of hepatitis B surface antibody positivity increased from 29.9% among children born in 1992 to 90.5% among children born in 2005, while the corresponding HBV infection rate decreased from 30.4% to 1.72%. Logistic regression indicated that, compared to children born between 1996 and 2001, the odds ratios (ORs) for timely initiation were 2.57 (95% confidence interval [CI], 1.71-3.84), 5.24 (95% CI, 3.26-8.43) and 9.06 (95% CI, 4.48-18.34) among children born in 2003, 2004 and 2005, respectively; the corresponding ORs for completing the vaccine series were 4.23 (95% CI, 1.97-9.10), 3.76 (95% CI, 1.81-7.82) and 4.94 (95% CI, 1.74-14.00) among children born in 2003, 2004 and 2005, respectively. Children with delayed vaccine initiation (>24 h after birth) were less likely to complete the vaccine series than those who received a timely first dose (OR = 0.02, 95% CI, 0.005-0.09). The impact of the free-vaccine policy on vaccine initiation and vaccine series completion did not differ by children's residence area (rural vs urban). As hypothesized, the odds of completing the vaccine series increased after the free-vaccine policy was announced in 2002 among children with delayed initiation (>24 h after birth) but not among those with timely initiation (≤ 24 h after birth). In conclusion, the free-vaccine policy significantly improved the timely initiation and completion of the vaccine series. The impact of this policy on completion of the vaccine series was larger among children with delayed vaccine initiation.

Five-year follow-up of a prospective study comparing laparoscopic Nissen fundoplication with Stretta radiofrequency for gastroesophageal reflux disease

AIM

Laparoscopic Nissen fundoplication (LNF) and Stretta radiofrequency (RF) are used as main alternative strategies to manage medication-refractory GERD. This study was therefore prospectively evaluated outcomes of patients with refractory GERD 5 years after LNF or Stretta RF.

METHODS

A total of 215 consecutive patients with refractory GERD underwent LNF (N.=102) and Stretta RF (N.=113) in our department between 2007 and 2008. They were followed-up for 5 years, during which the outcome measures including symptom scores of regurgitation, heartburn, chest pain, belching, hiccup, cough and asthma as well as the proton pump inhibitor (PPI) use and complications.

RESULTS

Of the 215 patients, 179 patients following LNF (N.=87) or Stretta RF (N.=92) completed the designated 5-year follow-up and were included in the final analysis. At the end of 5-year follow-up, the post-treatment scores were statistically lower as compared with the pre-treatment scores in both groups, while the symptom improvements after Stretta were significantly lower than that after LNF (p < 0.05). Besides, 81 (91%) patients achieved complete PPI therapy independence after LNF, comparing with 47 (51.1%) after Stretta RF (P<0.05). No significant differences in post-treatment complications were observed except for the abdominal distention.

CONCLUSION

Even though laparoscopic Nissen fundoplication and Stretta RF are capable of controlling GERD symptoms effectively and safely in selected patients, LNF could improve more in symptoms and PPI elimination.

Blockade of alpha1-adrenoceptors and cardiac depressant effect by a newly synthetic antihypertensive drug, DL-017 of quinazoline derivative

The electromechanical effects of 3-[[4-(2-methoxy phenyl)piperazin-1-yl]methyl]-5-(methylthio)-2,3-dihydroimidazo[1,2-c]quinazoline (DL-017), a newly synthesized quinazoline-derived antihypertensive agent, on mammalian cardiac tissues were evaluated. In driven canine Purkinje fibers, DL-017 decreased twitch tension, the maximal rate of upstroke of the action potential (Vmax), and intracellular Na+ activity (a(i)Na) in a concentration-dependent manner. The action potential duration was decreased in canine Purkinje fibers but increased in guinea pig papillary muscles. In guinea pig ventricular papillary muscles, phenylephrine in the presence of 1 microM propranolol increased the twitch tension in a concentration-dependent manner. At 10 microM, phenylephrine significantly decreased a(i)Na and shortened the action potential duration. DL-017 at 0.01 microM inhibited these phenylephrine-induced effects and shifted the concentration-dependent curve to the right. In sinoatrial nodes, DL-017 inhibited pacemaker activity, involving decreases in the slope of diastolic depolarization and Vmax and an increase in a delay of repolarization. These results suggest that, in addition to blockade of alpha1-adrenoceptors and Na+ channels, DL-017 reduces cardiac excitability and contractility in association with inhibition of slow inward Ca2+ and outward K+ channels. Since two order higher concentrations are required, the contribution of DL-017 to cardiac depressant from blockade of ionic channels seems to be less important when this compound is clinically used as an antihypertensive drug.

Coupling of the TCR to integrin activation by Slap-130/Fyb

SLAP-130/Fyb (SLP-76-associated phosphoprotein or Fyn-binding protein; also known as Fyb/Slap) is a hematopoietic-specific adapter, which associates with and modulates function of SH2-containing leukocyte phosphoprotein of 76 kilodaltons (SLP-76). T cells from mice lacking SLAP-130/Fyb show markedly impaired proliferation following CD3 engagement. In addition, the T cell receptor (TCR) in SLAP-130/Fyb mutant cells fails to enhance integrin-dependent adhesion. Although TCR-induced actin polymerization is normal, TCR-stimulated clustering of the integrin LFA-1 is defective in SLAP-130/Fyb-deficient cells. These data indicate that SLAP-130/Fyb is important for coupling TCR-mediated actin cytoskeletal rearrangement with activation of integrin function, and for T cells to respond fully to activating signals.

The changes of vitreous pH values in an acute glaucoma rabbit model

The changes of vitreous pH values under acute glaucoma status have never been reported. In this study, we measured the changes of vitreous pH values in an acute glaucoma rabbit model. Under ketamine and xylazine anesthesia, the anterior chamber of the right eye of New Zealand white rabbits was cannulated and connected to a polygraph for continuous intraocular pressure (IOP) monitoring and a mini-pump for persistent injection of viscoelastic substance, Healon GV. The measurement of vitreous pH was done by inserting a pH probe via a third opening through the sclera into the vitreous. Different IOP levels were maintained by varied amounts of Healon GV injections into the anterior chamber. The changes of vitreous pH values following the intracameral injections were recorded and evaluated. The changes of vitreous pH values were minimal when IOPs were maintained at lower than 35 mmHg. Vitreous pH values decreased significantly from 7.32 to less than 7.03, when the IOPs were kept at 70 mmHg or higher. However, the decrease of pH values was reversible if IOP was held at 70 mmHg for less than 10 minutes and then reduced to normal level at once. In addition, with MTT viability assay, it was noted that the decrease in vitreous pH was associated with a higher percentage of retinal cell death.

Blunted renal responses to angiotensin II infusion in lifetime captopril-treated spontaneously hypertensive rats

Previously, we had found that inhibition of the renin-angiotensin system in the early lifespan of spontaneously hypertensive rat could prevent the development of hypertension in this animal model. In the present study we evaluated the responses of blood pressure and renal function to intracerebroventricular administration of angiotensin II in long-term captopril-treated spontaneously hypertensive rats. Spontaneously hypertensive rats had been mated and their pups were treated with captopril through drinking water after birth. Age-matched Wistar-Kyoto and spontaneously hypertensive rats drinking tap water were used as control groups. At 4 months of age, the basal mean arterial blood pressure of captopril-treated hypertensive rats was the lowest among those of controlled hypertensive and normotensive rats (98+/-5 vs. 160+/-4 and 126+/-4 mmHg, respectively). Intravenous administration of angiotensin II caused similar increments of blood pressure in all rat groups. However, intracerebroventricular administration of angiotensin II to captopril-treated hypertensive rats induced a significantly less increase of arterial blood pressure in comparison with other groups. The sensitivity of baroreflex in captopril-treated hypertensive rats was also the lowest among all rat groups. The basal urine flow, sodium and potassium excretion rates, and osmolar clearance of captopril-treated hypertensive rats were significantly higher than those of controlled hypertensive rats. Intracerebroventricular infusion of angiotensin II caused significant increases in urine flow, electrolytes excretion, osmolar clearance, and free water reabsorption rate of both normotensive and controlled hypertensive rats. However, the same angiotensin II treatment did not change any of the renal excretion indices in captopril-treated hypertensive rats. Our results suggest that lifetime captopril treatment can decrease the activity of the renin-angiotensin system in the brain of hypertensive animals, which caused increases in basal urine flow and excretion of electrolytes and enhanced the sensitivity of baroreflex. It is likely that changes in the renal and baroreflex functions underlie the prevention of hypertension elicited by long-term captopril treatment.

Vitamin D(3) attenuates 6-hydroxydopamine-induced neurotoxicity in rats

Previous reports have demonstrated that exogeneous administration of glial cell line-derived neurotrophic factor (GDNF) reduces ventral mesencephalic (VM) dopaminergic (DA) neuron damage induced by 6-hydroxydopamine (6-OHDA) lesioning in rats. Recent studies have shown that 1,25-dihydroxyvitamin D(3) (D3) enhances endogenous GDNF expression in vitro and in vivo. The purpose of present study was to investigate if administration of D3 in vivo and in vitro would protect against 6-OHDA-induced DA neuron injury. Adult male Sprague-Dawley rats were injected daily with D3 or with saline for 8 days and then lesioned unilaterally with 6-OHDA into the medial forebrain bundle. Locomotor activity was measured using automated activity chambers. We found that unilateral 6-OHDA lesioning reduced locomotor activity in saline-pretreated animals. Pretreatment with D3 for 8 days significantly restored locomotor activity in the lesioned animals. All animals were sacrificed for neurochemical analysis 6 weeks after lesioning. We found that 6-OHDA administration significantly reduced dopamine (DA), 3,4-dihydroxy-phenylacetic acid (DOPAC) and homovanilic acid (HVA) levels in the substantia nigra (SN) on the lesioned side in the saline-treated rats. D3 pretreatment protected against 6-OHDA-mediated depletion of DA and its metabolites in SN. Using primary cultures obtained from the VM of rat embryos, we found that 6-OHDA or H(2)O(2) alone caused significant cell death. Pretreatment with D3 (10(-10) M) protected VM neurons against 6-OHDA- or H(2)O(2)-induced cell death in vitro. Taken together, our data indicate that D3 pretreatment attenuates the hypokinesia and DA neuronal toxicity induced by 6-OHDA. Since both H(2)O(2) and 6-OHDA may injure cells via free radical and reactive oxygen species, the neuroprotection seen here may operate via a reversal of such a toxic mechanism.

Prenatal exposure to morphine alters kinetic properties of NMDA receptor-mediated synaptic currents in the hippocampus of rat offspring

Whole-cell patch-clamp recordings of pharmacologically isolated N-methyl-D-asparate (NMDA) receptor-mediated evoked excitatory postsynaptic currents (EPSCs) were made, to study whether prenatal exposure to morphine affected functional properties of synaptic NMDA receptors in hippocampal slices of 2-week-old rat offspring from morphine-addicted mothers. The saturated amplitude of synaptic NMDA receptor-mediated EPSCs from morphine-treated offspring was about twofold larger than that from vehicle-control offspring. The apparent dissociation constant (Kd) values of NMDA receptors for Mg2+ at 0 mV were 7.5 +/- 1.4 and 7.9 +/- 1.3 mM in slices from vehicle-control and morphine-treated offspring, respectively. In addition, no distinguishable changes in the voltage-dependent nature and the reversal potential of NMDA receptors occurred in morphine-treated offspring, suggesting no alterations of Mg2+ blockade and ion selectivity to NMDA receptors. The 10-90% rise times of NMDA receptor-mediated EPSCs in morphine-treated offspring became longer than those in vehicle-control offspring. The decay of NMDA receptor-mediated EPSCs in both morphine-treated and vehicle-control offspring could be described by the sum of a fast and a slow exponential function. The slow, but not fast, decay times of synaptic NMDA receptor-mediated currents in morphine-treated offspring became slower than those in vehicle-control offspring. Collectively, these results suggest that prenatal exposure to morphine altered kinetic properties of synaptic NMDA receptors in hippocampal CA1 pyramidal neurons of rat offspring during early life. The extended duration of synaptic NMDA receptor-mediated currents presumably provided more Ca2+ entry through NMDA receptors in morphine-treated offspring, and its further prolongation by depolarization in such young offspring strengthened NMDA receptor-dependent functions. Thus, in light of pathophysiological implications within the central nervous system of morphine-treated offspring during early life, the present study may provide important insights and serve as a basis for therapeutic intervention in conditions under which NMDA receptors become abnormal.

Prolonged exposure to hyperbaric oxygen induces neuronal damage in primary rat cortical cultures

While seizure attack is one of the serious complications during the hyperbaric oxygen (HBO) therapy, there is still no direct evidence showing that HBO can induce neuronal damage in the brain. The objective of this study was first to investigate whether HBO would lead to neurotoxicity in the primary rat cortical culture. Second, since alterations in neurotransmitters have been suggested in the pathophysiology of central nervous system (CNS) oxygen toxicity, the protective effects of the N-methyl-D-aspartate (NMDA) receptor antagonism and nitric oxide (NO) synthase inhibition on the HBO-induced neuronal damage were examined. The results showed that HBO exposure to 6 atmosphere absolute pressure (ATA) for 30, 60, and 90 min increased the lactate dehydrogenase (LDH) activity in the culture medium in a time-dependent manner. Accordingly, the cell survival, measured by the 3,(4,5-dimethyl-2-thiazolyl)2, 5-diphenyl-tetrazolium bromide (MTT) assay, was decreased after HBO exposure. Pretreatment with the NMDA antagonist MK-801 protected the cells against the HBO-induced damage. The protective effect was also noted in the cells pretreated with L-N(G)-nitro-arginine methyl ester, an NO synthase inhibitor. Thus, our results suggest that activation of NMDA receptors and production of NO play a role in the neurotoxicity produced by hyperbaric oxygen exposure.

Activation of gonadotropin-releasing hormone receptors produces neuronal excitation in the rat hippocampus

Whole-cell patch-clamp recordings of evoked action potentials were made in CA1 and CA3 pyramidal neurons of rat hippocampal slices. Previously we have demonstrated that activation of gonadotropin-releasing hormone (GnRH) receptors induces a long-lasting enhancement of synaptic transmission mediated by ionotropic glutamate receptors in CA1 pyramidal neurons of rat hippocampal slices. Here, we further studied whether activation of GnRH receptors could modulate intrinsic neuronal excitability in CA1 and CA3 pyramidal neurons of rat hippocampal slices. The use of a specific GnRH analog, leuprolide (10(-8) M), elicited a relatively long-term increase in evoked action potentials in CA1 and CA3 pyramidal neurons, respectively. The GnRH receptor-induced increase in evoked action potentials in both CA1 and CA3 pyramidal neurons could be abolished by a potent GnRH receptor antagonist, [acetyl-3,4-dehydro-Pro1,D-p-F-Phe2,D-Trp(3,6)]-LHRH (10(-8) M). The present study suggests that activation of GnRH receptors can lead to an increase of intrinsic neuronal excitability of both CA1 and CA3 pyramidal neurons in the rat hippocampus, an important integrative region for reproductive process, both endocrinologically and behaviorally.

Activation of gonadotropin-releasing hormone receptors induces a long-term enhancement of excitatory postsynaptic currents mediated by ionotropic glutamate receptors in the rat hippocampus

Whole-cell patch-clamp recordings were made from CA1 pyramidal neurons of the rat hippocampus to study the modulation of gonadotropin-releasing hormone (GnRH) on synaptic transmission mediated by ionotropic glutamate receptors. Leuprolide (10(-9)-10(-7) M), a specific GnRH analog, concentration-dependently elicited a long-lasting potentiation of excitatory postsynaptic currents (EPSCs) mediated by ionotropic glutamate receptors. GnRH receptor-induced synaptic potentiation was blocked by 1 microM [Acetyl-3,4-dehydro-Pro1,D-p-F-Phe2,D-Trp3,6]-LHRH, a specific GnRH receptor antagonist. Furthermore, GnRH receptor-induced synaptic potentiation was associated with the stimulation of protein kinase C (PKC), being considerably attenuated by a potent PKC inhibitor (30 microM H-7). The results suggest a long-term enhanced modulation of GnRH on synaptic transmission mediated by ionotropic glutamate receptors, possibly via the actions of PKC in the hippocampus that is an important integrative system in the regulation of reproductive processes.

Free radicals are involved in methylmethacrylate-induced neurotoxicity in human primary neocortical cell cultures

Methylmethacrylate monomer (MMA), a highly volatile material, has been extensively used for the construction of complete or partial dental prostheses. While previous studies have indicated a variety of complications and untoward side-effects associated with its use, the possible neurotoxicity induced by this monomer has not been addressed. In this study, we have investigated the MMA-produced neuronal injury in human neuron-enriched primary culture. Embryonic brain tissue (8-10 weeks postconception) was used for the primary neuron-enriched culture. Phase-contrast microscopy was used to evaluate morphological changes of cultured neurons. Extracellular concentrations of lactate dehydrogenase (LDH) and nitrite was measured from the culture medium to assess the magnitude of neuronal damage and nitric oxide formation, respectively. Neocortical neurons exposed to the monomer (1/200, Vmonomer/Vglycerol) for two days resulted in a significant increase in the LDH level but monomer (1/20000, 1/2000, or 1/200; Vmonomer/Vglycerol) failed to increase the nitrite level. Morphologically, the neurons subjected to monomer treatment exhibited irregular shrunken cell bodies with dystrophic and/or fragmented neurities, or even cell lysis. Moreover, superoxide dismutase plus catalase or vitamin C pretreatment protected against monomer-induced neurotoxicity. Our results suggest that this neurotoxicity can not likely be attributed to the cytotoxic effects of nitric oxide but may be mediated through the toxicity of superoxide and other free radicals. This is the first time, to our knowledge, that neurotoxicity induced by MMA has been demonstrated in human cortical neurons.

The involvement of nitric oxide in synergistic neuronal damage induced by beta-amyloid peptide and glutamate in primary rat cortical neurons

Abnormal extracellular accumulation of beta-amyloid (Abeta), the major component of senile plaques in the Alzheimer's brain and the excitatory amino acid glutamate are both considered to be associated with neurodegeneration. We studied whether nitric oxide (NO) was involved in neuronal damage induced by Abeta and glutamate in primary rat cortical neurons. Our results demonstrated that (1) Both neuronal damage and NO production were synergistically induced by Abeta-(25-35) and glutamate; (2) This synergistic neuronal damage induced by Abeta-(25-35) and glutamate was attenuated by selective inhibitors of NO synthase. We propose that cytotoxic characteristics of NO, at least in part, are involved in the synergistic neuronal damage induced by Abeta and glutamate, presumably seen in Alzheimer's brains.

Isolation of yeast mutants defective for localization of vacuolar vital dyes

An application of flow cytometric sorting is used for isolation of Saccharomyces cerevisiae mutants that mislocalize vacuolar vital dyes. This screen is based on the ability of a lipophilic styryl compound, N-(3-triethylammoniumpropyl)-4-(6-(4-(diethylamino)phenyl)hexatrie nyl )pyridinium dibromide (FM4-64), to label endocytic intermediates from the plasma membrane to the vacuole membrane at 15 degreesC. Cells stained at 15 degreesC for both FM4-64 and carboxydichlorofluorescein diacetate (a vacuolar luminal vital stain), had a pronounced shift in red/green fluorescence from cells stained at 30 degrees or 38 degreesC. Flow cytometric selection based on this characteristic shift allowed the isolation of 16 mutants. These comprised 12 complementation groups, which we have designated SVL for styryl dye vacuolar localization. These groups were put into three classes. Class I mutants contain very large vacuoles; class II mutants have very fragmented vacuoles; and class III mutants show the strongest svl phenotype with punctate/diffuse FM4-64 staining. Limited genetic overlap was observed with previously isolated mutants, namely svl2/vps41, svl6/vps16, and svl7/fab1. The remaining svl mutants appear to represent novel genes, two of which showed temperature-sensitive vacuole staining morphology. Another mutant, svl8, displayed defects in uptake and sorting of phosphatidylcholine and phosphatidylethanolamine. Our flow cytometric strategy may be useful for isolation of other mutants where mislocalization of fluorescent compounds can be detected.

Metabotropic glutamate receptors are involved in calcium-induced LTP of AMPA and NMDA receptor-mediated responses in the rat hippocampus

Effects of metabotropic glutamate (mGlu) receptors on calcium-induced long-term potentiation (LTP) of alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionate (AMPA) and N-methyl-D-aspartate (NMDA) receptor-mediated components were investigated in rat hippocampal slices using whole-cell patch-clamp recordings of excitatory postsynaptic currents (EPSCs). Calcium-induced LTP comprises a parallel, long-lasting increase of AMPA and NMDA receptor-mediated components. The calcium-induced LTP of the AMPA receptor-mediated component can be significantly attenuated by the use of a selective NMDA antagonist. (R.S)-alpha-methyl-4-carboxyphenylglycine (MCPG), a selective antagonist of mGlu receptors, abolished the long-lasting increase of both AMPA and NMDA receptor-mediated components observed in calcium-induced LTP. In current clamp mode, the application of a high calcium alone or Schaffer fiber stimulation alone (20 Hz) only generated a short-term increase in the firing rate of evoked action potentials. Conversely, a long-term increase in the firing rate was observed if Schaffer fiber stimulation (20 Hz) accompanied the perfusion of high calcium. These results suggest that calcium-induced LTP involves a parallel, long-lasting enhancement in ionotropic AMPA and NMDA receptor-mediated components. More importantly, the mGlu receptor plays a critical role in the establishment of both AMPA and NMDA receptor-mediated components underlying calcium-induced LTP. In addition, the present study also described an experimental condition in which the coapplication of the high calcium pulse and Schaffer fiber stimulation (20 Hz) can synergistically elicit a long-term increase of neuronal excitability.

NMDA induces NO release from primary cell cultures of human fetal cerebral cortex

We and others have previously reported that N-methyl-D-aspartate (NMDA) induces nitric oxide (NO) release from the rat cerebral cortex in vivo. It is crucial to determine if this phenomenon also exists in human brain tissue. In this study, we investigated the interactions of NMDA and NO in human primary neocortical cell cultures obtained from elective abortions. Extracellular NO concentration was monitored through Nafion- and porphyrine-coated carbon fiber electrodes, which have previously been demonstrated sensitive and selective responses to NO. We found that local application of NMDA induced NO release from neocortical neuron-enriched cultures but not from glial cultures. Pretreatment with NG-nitro-L-arginine methyl ester hydrochloride (L-NAME), a nitric oxide synthase inhibitor, or MK801 significantly attenuated NMDA-induced NO overflow. This is the first time, to our knowledge, that extracellular NO concentration evoked by exogenous NMDA has been directly measured from the fetal human cortical neurons.

Blunted renal responses to atrial natriuretic peptide and its reversal by unclipping in one-kidney, one clip Goldblatt hypertensive rats

OBJECTIVE

To evaluate the hypotensive and renal effects of atrial natriuretic peptide (ANP) in one-kidney, one clip Goldblatt hypertensive rats with and without renal arterial stenosis.

METHODS

The one-kidney, one clip hypertensive rats were divided into four groups: untreated time control, ANP-infused, unclipped and unclipped plus ANP-infused. The changes in blood pressure, glomerular filtration rate and renal excretory function were determined during intravenous vehicle and ANP infusions while the renal arterial clip was in place or removed acutely. One-kidney normotensive rats infused with ANP were used for comparison.

RESULTS

In one-kidney control rats, ANP infusion at doses of 0.15, 0.30 and 0.45 microg/kg per min decreased the mean blood pressure from 121 +/- 4 to 108 +/- 5 (9%, P < 0.05), 104 +/- 5 (17%, P < 0.05) and 89 +/- 4 mmHg (25%, P < 0.05), respectively. There was no significant change in glomerular filtration rate. However, the absolute sodium excretion rate increased significantly, by 343 +/- 66, 770 +/- 91 and 786 +/- 78%, respectively. A comparable magnitude of increase in the fractional sodium excretion was noted. In one-kidney, one clip hypertensive rats, the similar three doses of ANP infusion reduced blood pressure from 179 +/- 7 to 162 +/- 8 (8%, P < 0.05), 146 +/- 9 (17%, P < 0.05) and 138 +/- 8 mmHg (22%, P < 0.05), respectively. A slight but insignificant increase in renal function was observed during ANP infusion. Removal of the renal arterial clip reduced blood pressure rapidly and caused a transient increase in renal function. Subsequent infusion of ANF further reduced blood pressure but increased sodium and water excretion markedly.

CONCLUSION

There is a blunted natriuresis and diuresis in response to ANP infusion in one-kidney, one clip hypertensive rats. Surgical removal of the clip from the renal artery restores the natriuretic and diuretic effects of ANP.

Prevalence of histoplasmin sensitivity in healthy adults and tuberculosis patients in southwest China

Two hundred and seventy-one healthy students and workers and 28 hospitalized tuberculosis patients living in Sichuan Province (southwest People's Republic of China; PRC) were tested with histolyn and tuberculin. The age of the tested subjects ranged from 17 to 22 years among the students, 17 to 38, among the workers and 17 to their 70s among the patients. Thirty-eight students (24%), 21 workers (18%) and 8 patients (29%) reacted positively to histolyn, none of the differences being statistically significant. Positive reactions were significantly more frequent among students from the south of Sichuan Province (35%) than from the north (6%). The rates of positive reaction to tuberculin in the students (25%) and in the workers (27%) indicates that tuberculous infection continues to be a significant problem in southwestern PRC. The significant rate of histolyn reaction among the tuberculosis patients raises the possibility of either infection with both Histoplasma capsulatum and Mycobacterium tuberculosis, or a missed diagnosis of chronic pulmonary histoplasmosis.

Changes in renal angiotensin II receptors in spontaneously hypertensive rats by early treatment with the angiotensin-converting enzyme inhibitor captopril

We tested the hypothesis that in utero treatment with the angiotensin-converting enzyme inhibitor captopril could change the affinity, density, and/or subtypes of angiotensin II (Ang II) receptors in the kidneys of spontaneously hypertensive rats (SHR). Newborn, 7-day-old, and 4-month-old SHR and Wistar-Kyoto (WKY) rats were used. SHR and WKY rat breeders were treated with captopril (0.4 mg/mL, 100 mg/kg per day) in drinking water, and their pups were maintained on captopril treatment until experimentation. Control groups were untreated, age-matched SHR and WKY rats. The density, affinity, and subtypes of renal Ang II receptors were determined using radioligand binding techniques and receptor antagonists specific for Ang II receptor subtypes 1 and 2 (losartan, an AT1-specific antagonist, and CGP 42112B, an AT2-specific antagonist). AT1 receptor density in kidneys was higher than AT2 receptor density in both neonatal and adult rats. AT1 receptor density in kidneys increased approximately twofold from birth to 7 days of age in all groups. Newborn and 7-day-old SHR showed significantly greater Ang II receptor densities in kidneys than other rat groups because of significantly greater densities of both AT1 and AT2 receptors. At 4 months of age, there were no significant differences in Ang II receptor densities in kidneys between captopril-treated and control SHR. Our data indicate that the expression of AT1 and AT2 receptors in kidneys is differentially regulated during development. Enhanced activity of the renal renin-Ang II system in newborn and probably fetal SHR may be involved in the pathogenesis of hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of genetic hypertension by early treatment of spontaneously hypertensive rats with the angiotensin converting enzyme inhibitor captopril

Our purpose was to evaluate whether early treatment of spontaneously hypertensive rats (SHR) with the angiotensin converting enzyme inhibitor captopril could permanently alter the course of hypertension. Mating pairs of SHR were treated with captopril, and their pups were maintained on captopril until experimentation. Some captopril-treated rats were taken off treatment at 2 months of age, and then some of these rats were mated at 3 months of age. The mean arterial pressures of conscious captopril-treated rats, the rats removed from therapy, and the offspring of the rats removed from therapy were significantly smaller than control rats at 4 and 9 months of age. Central administration of angiotensin I or II induced significantly smaller increases in blood pressure and drinking in captopril-treated rats and the rats removed from therapy compared with control rats. The increase in blood pressure in response to intravenous injection of angiotensin I or II was similar among all groups, with the exception that captopril-treated rats showed lesser pressor responses to angiotensin I. Early administration of captopril, even after administration was stopped, prevented the subsequent development of hypertension in SHR and altered the course of development of hypertension in their progeny. This effect was associated with decreased central responses to angiotensin I and II. Our data suggest that captopril may permanently alter the development of hypertension in SHR through an alteration in the central renin-angiotensin system.

Angiotensin-converting enzyme inhibition causes deterioration in renal function in one-kidney Goldblatt hypertensive rats with and without renal arterial stenosis

1. The renal and hypotensive effects of a new angiotensin-converting enzyme (ACE) inhibitor, cilazapril, were evaluated in 18 one-kidney, one-clip Goldblatt hypertensive rats (1K1C), 10 one-kidney normotensive rats (1K) and eight 1K1C rats with acute unclipping (1KU). Cilazapril was infused intravenously (25 micrograms/kg per min) into anaesthetized rats, and the arterial blood pressure (BP) and renal clearance of rats were measured. 2. In 1K rats, cilazapril reduced BP from 123 +/- 4 to 117 +/- 4 mmHg (P < 0.05), and produced diuresis, natriuresis and kaliuresis without significantly changing glomerular filtration rate (GFR). 3. In 1K1C rats, cilazapril significantly reduced BP (from 157 +/- 5 to 143 +/- 6 mmHg; P < 0.05), GFR (14.4 +/- 6.7%), urine flow (27.1 +/- 8.5%) and sodium excretion (39.4 +/- 7.4%). Mechanically graded reductions of renal arterial pressure alone also produced parallel decreases in GFR and renal excretory function. 4. In 1KU rats, removal of the renal arterial clip significantly decreased BP and increased renal function. Subsequent infusion of cilazapril further reduced BP and urinary excretions of sodium and water but did not significantly change GFR. 5. These results suggest that the renal function of the 1K1C hypertensive model is pressure-dependent, and that ACE inhibitor exerts a mild antihypertensive effect but causes a pressure associated reduction in renal function. Furthermore, the detrimental effect of ACE inhibitor on the residual kidney persists after acute surgical correction of the stenosis.

Skin sensitivity to histolyn, spherulin, and PPD in the People's Republic of China

One hundred one subjects living in northwest Hunan Province, People's Republic of China (PRC) were tested with histolyn, (Berkeley Biological Laboratories), spherulin (Berkeley Biological Laboratories), and tubersol (PPD 5 tuberculin units, Connaught Laboratories). Age of the tested subjects ranged from 16 to 58 years; 93 subjects were 22 years old or younger. Nine subjects reacted to histolyn with 5.0 mm or more induration, two subjects reacted to spherulin, and 34 subjects reacted to tubersol. One of the spherulin reactors also reacted to both histolyn and tubersol. The feasibility and advisability of doing a large-scale survey throughout the PRC seem clearly supported by this pilot project.

[Effect of endothelin on the release of angiotensin II from rat cardiovascular system]

The existence of angiotensin II immunoreactive substance in rat cardiovascular system was demonstrated by RIA and immunohistochemistry techniques. In atrium, aorta and cultured rat aorta smooth muscle cells, angiotensin II content is 7.2 + 2.7 pg/mg protein, 152.4 + 59.2 pg/mg protein and 3.5 + 0.8 pg/2 x 10(5) cells respectively. Endothelin, a potent vasoconstricting polypeptide, can enhance the release of angiotensin II from cultured rat aorta and aortic smooth muscle cells significantly. The results suggest that endothelin may be involved in the regulation of local blood flow and vascular tone, and it may also implicate the pathogenesis of some cardiovascular diseases such as cardiohypertrophy and vascular hypertrophy.

Effect of fructose-induced hypertension on the renin-angiotensin-aldosterone system and atrial natriuretic factor

Studies were performed to examine the effects of a high fructose intake on blood pressure, the renin-angiotensin-aldosterone system, and atrial natriuretic factor in normal rats. Sprague-Dawley rats were fed with either normal rat chow or a fructose-enriched diet for four or seven weeks. High dietary fructose consumption induced hyperinsulinemia and hypertriglyceridemia, and increased the systolic blood pressure by 19 +/- 4 mm Hg (four weeks of diet) and 24 +/- 1 mm Hg (seven weeks of diet), respectively. There were no significant changes in the plasma renin activity at either time. However, an increase in plasma atrial natriuretic factor was noted in rats treated with a high fructose diet for four weeks, and a decrease in plasma aldosterone was found in those rats fed with fructose for a longer period. There was no significant difference in body weight gain between rats fed with fructose-enriched diet and those fed with control diet. These data indicate that the increase in blood pressure associated with a high fructose intake is not due to a direct effect or the renin-angiotensin-aldosterone system.

Differential renal responses to atrial natriuretic peptide in two-kidney, one clip goldblatt hypertensive rats

Bilateral renal clearance experiments were performed to examine the effects of synthetic rat atrial natriuretic peptide (ANP, atriopeptin II) on the arterial blood pressure (BP) and individual kidney function in anesthetized 2-kidney, 1 clip Goldblatt hypertensive rats (n = 14) and normotensive rats (n = 15). Bolus administration of graded doses of ANP from 2.5 to 10 micrograms/kg produced dose-related reductions in BP in hypertensive and normotensive rats. Despite profound reductions in BP, there were significant increases in glomerular filtration rate, urine flow, absolute and fractional excretion rates of sodium and potassium, osmolar clearance, and free water clearance in the nonclipped kidney, whereas no significant changes in these renal indices occurred in the clipped kidney. The enhanced renal responses were dose-dependent. The normal kidney responded to ANP with similar magnitude. When ANP was infused intravenously (0.3 microgram/kg.min i.v.) during 2 h, BP maximally reduced by 36 +/- 2 mm Hg (24 +/- 1%) in the hypertensive group and by 27 +/- 2 mm Hg (22 +/- 2%) in the control group. Again, there were distinct renal responses between the two kidneys of hypertensive rats. These results indicate that ANP effectively reduces BP and preferentially increases the excretory function of the nonclipped kidney without compromising the function of the clipped kidney in this hypertensive model.

Effect of unilateral renal denervation on bilateral renal response to saline loading in anteroventral third ventricle-lesioned rats

Our previous experiments demonstrated that lesions in the anteroventral third ventricle (AV3V) region of the brain attenuated natriuretic and diuretic response to saline loading in rats. To further assess if renal nerves are involved in this impaired response, we compared the effect of acute unilateral renal denervation on the response to saline loading in AV3V-lesioned and intact rats. Rats with electrolytic ablation in the AV3V region were prepared 4 weeks prior to experiments. The arterial blood pressure (BP) and bilateral renal responses to acute expansion of plasma volume by saline loading (0.388 ml/min for 1 h) were measured in rats under pentobarbital anesthesia. Saline loading before renal denervation induced a smaller increase in bilateral renal excretion of sodium and water in AV3V-lesioned rats than in control rats. Acute renal denervation produced ipsilateral natriuresis and diuresis without causing significant change in the excretory functions of the contralateral kidneys in both the lesioned and the control rats. BP and glomerular filtration rate of both groups of rats remained unaltered. The denervation-induced natriuretic and diuretic responses in the lesioned rats were not significantly different from those of the control rats. Subsequent saline loading increased bilateral renal excretion of sodium and water in both groups of rats. However, the previously observed attenuation of natriuretic and diuretic responses to saline loading in rats with AV3V lesions was abolished after renal denervation. These results suggest that the integrity of the AV3V region is necessary for normal regulation of sodium and water balance. Furthermore, there is a functional connection between the renal nerve and the AV3V region in modulating renal excretion during volume expansion.

Effect of angiotensin converting enzyme inhibition on renal response to atrial natriuretic factor in rats

Previous studies have shown that atrial natriuretic factor (ANF) inhibits renin secretion whereas cilazapril blocks angiotensin II generation via converting enzyme inhibition. Both agents enhance renal excretory function. The present study was conducted to test whether the renin-angiotension system is involved in the ANF-induced renal effects. ANF was administered to anesthetized normal rats (n = 16) with or without a simultaneous infusion of cilazapril. Single bolus injections of ANF at doses of 2.5 micrograms/kg and 5.0 micrograms/kg significantly decreased mean arterial blood pressure by 6.8 +/- 2.3% and 9.4 +/- 2.2%, respectively. The corresponding increases in glomerular filtration rate were 5.6 +/- 3.7% and 8.4 +/- 2.8%, in absolute sodium excretion were 55.0 +/- 18.5% and 105.2 +/- 39.9%, and in urine flow were 24.8 +/- 9.3% and 35.6 +/- 14.6%. Intravenous infusion of cilazapril (33 micrograms/kg.min) reduced the arterial blood pressure, elevated the glomerular filtration rate and increased sodium and water excretion. The corresponding doses of ANF administration during continuous infusion of cilazapril further decreased blood pressure by 8.3 +/- 1.9% and 10.9 +/- 5.4%, respectively. However, there were no significant changes in the glomerular filtration rate and sodium and water excretion. The failure of ANF to exhibit a renal effect was irrelevant to the lowering blood pressure induced by cilazapril. These results suggest that reduced endogenous angiotensin II generation contributes to the renal, but not the hypotensive, effect of ANF.

Effects of lead on viability and intracellular metal content of C6 rat glioma cells

Cultured C6 rat glioma cells were exposed to lead (Pb) acetate (0, 1, 10, or 100 microM) for 3-4 d. Cells were analyzed for changes in viability and intracellular lead, iron, and copper concentrations after Pb treatment was discontinued. The results were compared with previous findings on astroglia and oligodendroglia in culture in order to evaluate C6 cultures as a model for Pb toxicity in glia. Viability was measured by three methods on the day Pb was removed from the cells (designated d 0), and 2 and 9 d after Pb treatment was discontinued (designated d 2 and 9). The methods used were trypan blue dye exclusion, total cell counts, and incorporation of [3H]-L-leucine into proteins. Small, dose-dependent reductions were observed on d 2 in the percentages of cells excluding dye. Decreased cell numbers were seen at all three Pb doses only on d 0. With respect to these two viability measurements, C6 cells responded like astroglia in culture to Pb, but not like oligodendroglia, which are more Pb-sensitive. We expected decreased amino acid incorporation to accompany the decreased viability of the cultures. Instead, increased amino acid incorporation, which indicates increased protein synthesis, was seen on d 0 and 2 at all three Pb doses, though total cellular protein did not increase. A similar response has been reported previously in oligodendroglial cultures. C6 cells treated for 3 with 1 or 100 microM Pb acetate were analyzed for intracellular metal content by atomic absorption aspectroscopy on d 4 and 11 after exposure to Pb was discontinued. The cells were found to take up large amounts of Pb intracellularly and store it for at least 11 d. Cells treated with FeCl2 instead of Pb took up Fe, but required a higher extracellular Fe concentration to achieve an intracellular Fe level comparable to that of Pb in Pb-treated cells. Pb uptake did not affect intracellular Fe or Cu concentrations. With respect to Pb and Fe uptake, C6 cells closely resembled immature astroglia in culture. Unlike C6 cells, however, astroglia showed elevations of intracellular Fe and Cu after Pb treatment. Thus, Pb effects on C6 cells resembled those on cultured oligodendroglia and astroglia in some respects but not in others. C6 cells appear to be an adequate model for selected events in glial toxicosis, such as Pb-stimulated protein synthesis in oligodendroglia and Pb uptake in astroglia, but not Pb-induced alterations of intracellular Cu and Fe in astroglia. Their use as a model for glial progenitor cells in Pb toxicity studies remains to be determined.

Reduction by lead of hydrocortisone-induced glycerol phosphate dehydrogenase activity in cultured rat oligodendroglia

Time- and dose-dependent toxic effects of lead (Pb) acetate on astroglia, oligodendroglia, and meningeal fibroblasts cultured from immature rat brain were measured. Cultures were exposed for 3 d to Pb (1, 10, and 100 microM) and then examined immediately (Day 0) or 3 or 10 d after Pb treatment was discontinued. The percentages of astroglia and fibroblasts excluding dye were unaffected by Pb, whereas the percentage of oligodendroglia excluding dye decreased significantly (P less than 0.01) at all time points after exposure to 100 microM Pb. Lead (100 microM) also reduced the total cell numbers of astroglia, oligodendroglia, and meningeal fibroblasts. Amino acid incorporation into protein by oligodendroglia was stimulated after exposure to 100 microM Pb at all time points and also by 1 and 10 microM on Day 3. Incorporation was stimulated in astroglia only on Day 0 by 10 and 100 microM. Hydrocortisone-stimulated glycerolphosphate dehydrogenase (GPDH) activity was assayed in oligodendroglia cultures. A significant decrease in specific activity was seen after a 4-d exposure to lead. Because oligodendroglia are responsible for myelin synthesis in the central nervous system, and GPDH may synthesize a precursor for myelin lipid synthesis, it was proposed that the hypomyelination observed in lead-intoxicated neonatal rats may result partially from a primary toxic effect on oligodendroglia. GPDH activity was not inhibited by Pb in mixed glial cultures containing both astroglia and oligodendroglia. This result suggests that astroglia in culture have the ability to delay the lead-induced inhibition of oligodendroglial GPDH activity and supports the hypothesis that astroglia in culture serve a protective function.

Antihypertensive and bilateral renal responses to diuretics in 2-kidney, 1-clip Goldblatt hypertensive rats

Experiments were conducted to assess the effect of furosemide or amiloride alone and a combination of both agents on each kidney in anesthetized 2-kidney, 1 clip Goldblatt hypertensive rats (n = 25). Intravenous infusion of furosemide alone (1.02 mg/kg.hr) significantly reduced the blood pressure by 14 +/- 5 mmHg. There were 6- to 10-fold increases in water, absolute sodium and fractional sodium excretions and a 2-fold increase in potassium excretion in the nonclipped kidney. A smaller but significant increase in the excretory function was also observed in the clipped kidney. There was no significant change in GFR of both kidneys. Indomethacin pretreatment (2 mg/kg) failed to significantly alter the vasodepressor and renal responses to furosemide in both hypertensive and normal rats. Removal of the renal artery clip from the hypertensive rats reduced the blood pressure by 12 +/- 3 mmHg and enhanced the function of the ipsilateral, unclipped kidney. Subsequent administration of furosemide further increased the excretory response. Administration of amiloride alone (2.4 mg/kg.hr) or with furosemide into hypertensive rats reduced the arterial pressure and increased excretion rates of urine flow and urinary sodium. Potassium excretion rate decreased bilaterally in amiloride treated rats but did not alter significantly in rats which received a combination of amiloride and furosemide. These results indicate that diuretics ameliorate the excretory function of both the stenotic kidney and the nonstenotic kidney and that the improvement of the kidney function is independent of prostaglandin. Furthermore, removal of the stenosis accentuates the beneficial effect of diuretics on the kidney.

Effects of lead treatment on intracellular iron and copper concentrations in cultured astroglia

Astroglia are implicated in the pathogenesis of lead (Pb) neurotoxicity in two capacities: as a lead sink that sequesters lead and as a target for direct cellular damage. A proposed cellular mechanism of Pb neurotoxicity is the alteration of metal concentrations, particularly the intracellular accumulation of Cu2+. We measured Pb uptake and the effects of Pb acetate on intracellular trace metal concentrations in astroglial cultures prepared from 0- to 4-day-old rat cerebral hemispheres. Mature Sprague Dawley and immature Wistar rat astroglia in culture took up lead from the medium. This finding replicates in vitro the finding reported by others that astroglia in the brain take up Pb. Intracellular Cu and Fe concentrations (micrograms per 2 x 10(6) cells) were increased fourfold or more by treatment with 100 microM Pb for 3 days in the cultures of immature astroglia. Cu levels were also increased twofold or more in mature astroglia treated for 1-3 days with 100 microM Pb. The significance of this finding is that Cu is a potent inhibitor of Na+, K+-ATPase, an enzyme by which astroglia are thought to remove K+ from the extracellular fluid in the brain. Thus, this finding supports the hypothesis that elevated [Cu], and perhaps [Fe], is a subcellular mechanism of neurotoxicity.

Effect of sodium restriction and corticosteroids on glandular kallikrein in plasma and in the submandibular gland

We investigated whether sodium restriction or mineralocorticoid influence the release of submandibular kallikrein into the blood and/or the concentration of kallikrein in glandular tissue. For this we measured submandibular gland blood flow, arterial and submandibular gland venous kallikrein, and kallikrein in glandular homogenates of male Sprague-Dawley rats after one week of either low sodium or deoxycorticosterone acetate (DOCA) treatment. We also studied the effect of dexamethasone on the concentration of kallikrein in gland tissue and peripheral plasma. Kallikrein in plasma and in homogenates was measured by radioimmunoassay. Blood flow was determined by timed collections of venous outflow. Kallikrein release was calculated as the arteriovenous difference in kallikrein times the rate of submandibular gland plasma flow. The concentration of kallikrein in arterial plasma, the basal submandibular kallikrein release into blood, and the concentration of kallikrein in submandibular gland tissue were all higher during low sodium than during normal sodium intake (20.1 +/- 3.6 ng/ml vs 10.7 +/- 0.5, p less than 0.05; 0.40 +/- 0.09 ng/min/100 g bw vs 0.18 +/- 0.02, p less than 0.05, and 81.6 +/- 5.5 micrograms/mg protein vs 65.1 +/- 4.0, p less than 0.05, respectively). In contrast, DOCA treatment did not affect the concentration of kallikrein in arterial plasma, the basal release of kallikrein from the submandibular gland into blood, or the concentration of kallikrein in the gland. Dexamethasone in doses that did not affect the normal growth of the animals had no significant effect on the concentration of kallikrein either in submandibular gland tissue or in peripheral plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of increases in lung volume on clearance of aerosolized solute from human lungs

To study the effect of increases in lung volume on solute uptake, we measured clearance of 99mTc-diethylenetriaminepentaacetic acid (Tc-DTPA) at different lung volumes in 19 healthy humans. Seven subjects inhaled aerosol (1 micron activity median aerodynamic diam) at ambient pressure; clearance and functional residual capacity (FRC) were measured at ambient pressure (control) and at increased lung volume produced by positive pressure [12 cmH2O continuous positive airway pressure (CPAP)] or negative pressure (voluntary breathing). Six different subjects inhaled aerosol at ambient pressure; clearance and FRC were measured at ambient pressure and CPAP of 6, 12, and 18 cmH2O pressure. Six additional subjects inhaled aerosol at ambient pressure or at CPAP of 12 cmH2O; clearance and FRC were determined at CPAP of 12 cmH2O. According to the results, Tc-DTPA clearance from human lungs is accelerated exponentially by increases in lung volume, this effect occurs whether lung volume is increased by positive or negative pressure breathing, and the effect is the same whether lung volume is increased during or after aerosol administration. The effect of lung volume must be recognized when interpreting the results of this method.

Effect of urea-hydrogen peroxide on hypoxia in rabbits

PaO2 in hypoxemic rabbits was raised 30 min after intravenous administration of urea-hydrogen peroxide (U-H2O2). Peak levels appeared 2 h after administration of the drug and the effect continued up to 4 h. The treatment was effective and no side effects in the rabbits were observed. A new technique is described to produce hypoxemia in rabbits using a special mask. In contrast to previously described techniques the rabbits in this study could be kept alive with a stable hypoxemia for at least 4-5 h. This model may be useful for future studies requiring similar hypoxemic conditions in experimental animals.