Sexually transmitted coinfections among at-risk HIV-positive MSM: implications for optimal preemptive treatment

Background

Concurrent sexually transmitted infections (STIs) are common in sexually active populations. We aimed to estimate the prevalence and coinfection rates of bacterial STIs among sexually active, HIV-positive men who have sex with men (MSM), and to assess the potential benefits of different combination treatment regimens in managing concurrent bacterial STIs.

Methods

From September 2021 to September 2023, HIV-positive MSM underwent STI testing when they had symptoms suggestive of STIs or recently acquired hepatitis C virus (HCV) infection or early syphilis. The oral rinse, rectal swab, and urethral swab specimens were tested for Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma spp., Ureaplasma spp., and Trichomonas vaginalis with the use of multiplex real-time polymerase-chain-reaction assays. The estimated coinfection rates were used to evaluate the benefits of different combination treatment regimens for managing coinfections.

Results

During the study period, 535 participants (median age, 37 years; and CD4 count, 615 cells/mm3) were enrolled. On their first visits, at least one bacterial pathogen was detected in 57.9% and concomitant bacterial infections were found in 32.9% of the participants. The most commonly identified pathogen was U. urealyticum (36.3%), followed by C. trachomatis (22.8%), and N. gonorrhoeae (19.8%). The factors associated with any bacterial STIs included older age (per 1-year increase, adjusted odds ratio [AOR], 0.97; 95% confidence interval [CI], 0.95-1.00), early syphilis (AOR, 1.87; 95% CI, 1.22-2.84), and having more than 5 sex partners in the preceding 3 months (AOR, 2.08, 95% CI, 1.07-4.06). A combination therapy of benzathine penicillin G with a 7-day course of doxycycline could simultaneously treat 27.1% of C. trachomatis coinfections in participants with early syphilis, while a combination therapy of ceftriaxone with doxycycline could simultaneously treat 40.6% of chlamydial coinfections in participants with gonorrhea.

Conclusion

Bacterial STIs were prevalent and concomitant infections were not uncommon among sexually active, HIV-positive MSM, supporting regular screening for bacterial STIs. The effectiveness of preemptive use of doxycycline as combination therapy for concurrent STIs warrants more investigations.

[Effects and clinical significance of NLRP3 inflammasome activated by IL-17A in CRSwNP]

Objective: To investigate the effects and clinical significance of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activated by interleukin (IL)-17A in chronic rhinosinusitis with nasal polyps (CRSwNP). Methods: Patients underwent nasal endoscopic surgery in the Third Affiliated Hospital of Sun Yat-sen University from January 2020 to December 2021 were collected, including 28 CRSwNP (including 19 males and 9 females, aged 19 to 67 years), 22 chronic rhinosinusitis without nasal polyps (CRSsNP) and 22 controls. qRT-PCR was used to detect the expressions of IL-17A, NLRP3, IL-1β and IL-18 in the three groups, and their correlations were analyzed. The positions of IL-17A, NLRP3 and IL-18 in nasal polys were analyzed by immunofluorescence. Western Blotting and ELISA were employed to detect the expression of NLRP3, IL-1β and IL-18 in the human nasal epithelial cells after using IL-17A stimulation or IL-17A receptor inhibitor. Immunofluorescence was used to observe the NLRP3, IL-1β, and IL-18 protein expression after IL-17A stimulating human nasal epithelial cells, and after the use of IL-17A receptor inhibitor and NLRP3 inhibitor MCC950. The correlations between NLRP3, IL-1β, IL-18 and CT scores, nasal endoscopic scores, visual analogue scale (VAS) scores, and sino-nasal outcome test (SNOT) 22 scores of CRSwNP patients were analyzed. SPSS 20.0 software was used for statistical analysis. Results: The expressions of IL-17A, NLRP3, IL-1β and IL-18 in the tissues of CRSwNP patients were significantly higher than those in CRSsNP group(P=0.018,P<0.001,P=0.005, P=0.016) and the control group(all P<0.001). IL-17A was positively correlated with the expression of NLRP3, IL-1β, and IL-18(r ralue was 0.643,0.650,0.629,respectively, all P<0.05). IL-17A, NLRP3, and IL-18 were co-localized in the epithelial propria of polyp tissue. IL-17A stimulated the expressions of NLRP3, IL-1β, and IL-18 in human nasal epithelial cells. After the use of IL-17A receptor inhibitor, the expressions of NLRP3, IL-1β, and IL-18 were significantly down-regulated. After the use of NLRP3 inhibitor MCC950, IL-17A was significantly down-regulated to promote the expression of NLRP3, IL-1β, and IL-18. The expressions of NLRP3, IL-1β and IL-18 were positively correlated with CT, nasal endoscopy, VAS, and SNOT22 scores in patients with CRSwNP. Conclusions: IL-17A promotes the release of IL-1β and IL-18 by activating the NLRP3 inflammasome and aggravates the severity of the disease in CRSwNP.

[The expression profile and potential regulatory mechanism of ACE2 in chronic rhinosinusitis with nasal polyps]

Objective: To preliminarily analyze the expression of angiotensin-converting enzyme 2 (ACE2) and to investigate its potential regulatory mechanism in chronic rhinosinusitis with nasal polyps (CRSwNP). Methods: Patients underwent nasal endoscopic surgery in the Third Affiliated Hospital of Sun Yat-sen University from February 2020 to May 2021 were selected, including 17 males and 6 females, aging from 23 to 66 years old. Expression of ACE2 was evaluated via immunohistochemical staining in controls with non-chronic rhinosinusitis, non-eosinophilic CRSwNP (non-ECRSwNP), and eosinophilic CRSwNP (ECRSwNP) tissue, respectively. Correlations between ACE2 and the indicated Th1/Th2-related cytokines (IFN-γ, IL-4, IL-5, IL-13, IL-25, IL-33, TSLP and periostin) were analyzed based on GSE72713 dataset. Protein-protein interaction (PPI) network was constructed via string database, immune infiltration of GSE72713 dataset was evaluated using cibersort algorithm. ACE2 was comprehensively analyzed by microRNA regulatory network, gene set enrichment analysis (GSEA) and pharmacological analysis. Statistical analysis was performed using GraphPad 7.0 and SPSS 20.0 software. Results: ACE2 was up-regulated in non-ECRSwNP compared with ECRSwNP. Microarray analysis showed that ACE2 was positively correlated with IFN-γ while inversely correlated with IL-5, IL-13 and periostin significantly. Analysis of immune infiltration suggested that ACE2 expression correlated positively with the number of M1 macrophage while negatively with M2 macrophage. GSEA demonstrated that interferon-related signaling pathways were up-regulated in non-ECRSwNP, and miRNA-200B/miRNA-200C/miRNA-429 pathways targeting ACE2 were enriched in ECRSwNP. Results of pharmacological analysis indicated that ampicillin was able to promote the expression of ACE2 whereas acetaminophen could down regulated the expression of ACE2. Conclusion: Expression pattern of ACE2 is varied in non-ECRSwNP and ECRSwNP, which may be related to the different infiltration of indicated cytokines and different regulatory pathways of miRNA.

[Expression of CD8+Treg cells in chronic rhinosinusitis and its correlation with eosinophilic infiltration]

Objective: To detect the percentages of CD8⁺Treg cells in the nasal mucosa and peripheral blood of chronic rhinosinusitis (CRS) and to explore their correlation with eosinophilic infiltration. Methods: Thirty-three chronic rhinosinusitis with polyp (CRSwNP), 26 chronic rhinosinusitis without polyp (CRSsNP) and 27 control patients who were collected with the nose mucosal tissue and peripheral blood in the Third Affiliated Hospital of Sun Yat-sen University from March 2017 to October 2018 were selected, including 59 males and 27 females, aging from 18 to 72 years. Hematoxylin and eosin (HE) staining was used to observe the number of eosinophils in the nasal tissues and to classify the CRS into eosinophilic CRS (ECRS) and non-eosinophilic CRS (Non-ECRS). Flow cytometry was used to detect the percentages of CD4⁺ and CD8⁺T cells in lymphocytes of nasal mucosa and peripheral blood. The percentages of CD8⁺Foxp3⁺Treg cells, CD8⁺Foxp3^-IL-10⁺Treg cells, CD8⁺IFN-γ⁺T cells (Tc1), CD8⁺IL-4⁺T cells (Tc2) and CD8⁺IL-17A⁺T cells (Tc17) in lymphocytes of nasal mucosa and peripheral blood were also tested. Besides, the percentages of Foxp3⁺TGF-β⁺Treg cells and Foxp3⁺IL-10⁺Treg cells in CD8⁺T cells were determined. All data were represented by M (IQR). GraphPad 7.0 and SPSS 16.0 were used for illustration and statistical analysis. Results: The percentage of CD8⁺T cells (37.75%(17.35%)) was higher than that of CD4⁺T cells (4.72%(4.29%)) in nasal mucosa (Z=-5.70, P<0.001), while lower (23.60%(9.33%)) than that of CD4⁺T cells (44.05% (10.93%)) in peripheral blood (t=9.72, P<0.001). CRSwNP patients possessed the highest Tc2 (1.82% (1.22%)) and Tc17 (1.93% (2.32%)) percentages than CRSsNP (Tc2: 0.84% (0.79%); Tc17: 0.54% (1.04%)) and control (Tc2: 1.09% (0.92%); Tc17: 0.47% (0.51%), both P<0.05) patients. While, CRSwNP patients possessed the lowest CD8⁺Foxp3⁺Treg cells percentage (0.10% (0.32%)) than CRSsNP (0.43% (1.45%)) and control (0.48% (0.83%), Z value was -2.24, -2.22, respectively, P value was 0.025, 0.027, respectively). The percentages of Foxp3⁺TGF-β⁺Treg cells and Foxp3⁺IL-10⁺Treg cells of CD8⁺T cells in nasal mucosa in CRSwNP were also lower than controls (Z value was 1.46, 0.49, respectively, both P=0.001). Moreover, the percentage of CD8⁺Foxp3^-IL-10⁺Treg cells of CD8⁺T cells was decreased in nasal mucosa of CRSwNP patients (0.14% (0.28%)) when compared with that of CRSsNP (0.89% (0.81%), Z=0.61, P=0.03). ECRS patients had the lower percentages of CD8⁺Foxp3⁺Treg cells (0.07% (0.44%)) and CD8⁺Foxp3^-IL-10⁺Treg cells (0.13% (0.21%)) than Non-ECRS patients (CD8⁺Foxp3⁺Treg cells: 0.53% (0.75%); CD8⁺Foxp3^-IL-10⁺Treg cells: 0.29% (0.76%), t value was 2.14, 2.78, respectively, both P<0.05). The percentage of CD8⁺Foxp3⁺Treg cells and the ratio of CD8⁺Foxp3^-IL-10⁺T per CD8⁺T cells were negatively correlated with the percentage of eosinophils in CRS patients(R² value was 0.56, 0.78, respectively, both P<0.001). There was no significant difference in the distribution of CD8⁺Fxop3⁺Treg cells and CD8⁺Fxop3^-IL-10⁺Treg cells in peripheral blood among different groups. Conclusion: The percentages of CD8⁺Treg cells decrease in CRSwNP patients, especially in ECRS patients, which are opposite to that of Tc2 and Tc17, and negatively correlate with the eosinophils percentage. This indicates that the decrease in the ratio of CD8⁺Treg cell may be associated with the immune-imbalance and eosinophilic infiltration in nasal mucosa of CRS patients.

[miR-18a enhances the radiosensitivity of nasopharyngeal carcinoma cells through inducing autophagy]

Objective: To explore the impacts of miR-18a overexpression or depression on the radiosensitivities of nasopharyngeal carcinoma cell line CNE1 and CNE2 and underlying mechanisms. Methods: CNE1 and CNE2 were transfected with miR-18a mimics, inhibitor and the corresponding control vectors. qRT-PCR and western blot were used to determine the ataxia telangiectasia mutated (ATM) expressions in CNE1 and CNE2. CNE1 and CNE2 with stably expressing miR-18a and miR-18a siRNA were constructed. Methyl thiazolyl tetrazolium (MTT) assay was used to detect the impacts of the miR-18a overexpression or depression combined with irradiation on the cell growth. Flow cytometry was used to detect the cell apoptosis and cell cycle. Colony formation assay was used to evaluate the raodiosensitivities of cells. Acridine orange (AO) staining and western blot were used respectively to test the autophagy and the expressions of related proteins. Independent samples t test was used to compare the mean value between groups by using SPSS 16.0. Results: ATM mRNA was decreased significantly in CNE1 and CNE2 cells transfected with 100 or 200 nmol/L miR-18a mimics for 48 hours (CNE1: RQ=0.174±0.139 and 0.003±0.001, t=9.939 and 19 470.783;CNE2: RQ=0.024±0.008 and 0.019±0.012, t=270.230 and 137.746, respectively, all P<0.001). ATM proteins were also decreased after transfected with 100 or 200 nmol/L miR-18a mimics for 72 hours. While in the cells transfected with 100 and 200 nmol/L miR-18a inhibitor for 48 hours, the expressions of ATM mRNA were upregulated significantly (CNE1: RQ=9.419±2.495 and 2.500±1.063, t=-4.427 and -41.241; CNE2: RQ=7.210±0.171 and 115.875±15.805, t=-62.789 and -12.589, all P<0.05), and the expressions of ATM proteins increased after transfected for 72 hours. The growth of cells with miR-18a overexpression plus 4 Gy irradiation were obviously inhibited compared to that of cells with the 4Gy irradiation alone; while the growth of miR-18a-inhibited cells increased compared to that of cells with 4 Gy irradiation alone (all P<0.05). CNE1 transfected with 100 nmol/L miR-18a mimics plus 4 Gy irradiation showed the higher apoptosis rate than the cells with 4 Gy irradiation alone ((22.9±2.1)% vs. (16.3±1.0)%, t=-4.870, P<0.01). Compared to the cells with 4 Gy irradiation alone, miR-18a-overexpressed cells plus 4 Gy irradiation decreased their percentages in G1 phases ((20.2±3.0)% vs. (29.8±4.4)%, t=3.119) and G2/M phases ((21.5±0.9)% vs. (33.4±3.1)%, t=6.410, P<0.05 for both), and increased their percentages in S phases ((56.7±4.9)% vs. (36.8±6.4)%, t=-4.246, P<0.05), and these cells possessed less colony number after exposure to different doses of irradiation, more autophagy-lysosome number, and more expressions of LC3 proteins (all P<0.05). There were no significant differences in the expressions of p62 expressions between different groups of cells. Conclusion: Overexpression of miR-18a can enhance the radiosensitivities of NPC cells by targeting ATM to abrogate G1/S, G2/M arrest and to induce autophagy and apoptosis.

[The expression of Notch pathway in nasal polyps and its correlation with the decreased Treg percentage and eosinophil infiltration]

Objective: To investigate the correlation between Notch pathway expression in nasal polyps and Treg percentage and Eos infiltration. Methods: Patients with chronic sinusitis and simple nasal septum deviation who received nasal endoscopic surgery in the Third Affiliated Hospital of Sun Yat-Sen University between November 2012 and August 2018 were selected and enrolled in CRS group and control group respectively. Nasal mucosa tissues were collected from 30 CRSsNP patients (14 males and 16 females aged from 18 to 63), 58 CRSwNP patients (38 males and 20 females aged from 18 to 65) and 29 patients (19 males and 10 females aged from 20 to 57), who underwent nasal endoscopic surgery for correction of simple nasal septum deviation. Hematoxylin-eosin(HE) staining was used to observe the infiltration of eosinophilic granulocytes in the tissues and to classify chronic sinusitis with polyps (CRSwNP) into eosinophilic chronic rhinosinusitis with nasal polyps (Eos-CRSwNP)and non-eosinophilic chronic rhinosinusitis with nasal polyps (Eos-CRSwNP). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of Notch pathway receptors (Notch-l, 2, 3, 4) and their ligands (Jagded-l, Jagded-2, Delta-l, Delta-3and Delta-4) in the nasal mucosa of each group, as well as the expression of Th2 cytokines (IL-4, IL-5, IL-13), eosinophilic cationic protein (ECP)and the key transcription factor Foxp3 in Treg cells. Finally, flow cytometry was used to detect CD4+CD25+Foxp3+ Treg cells in nasal mucosa of each group. Results: Compared with controls, the expression of Th2 cytokines (IL-4, IL-5, IL-13) in CRSsNP and non-Eos-CRSwNP patients was the highest in Eos-CRSwNP (F=16.930,9.197,9.116, all P<0.05). Foxp3 had the lowest expression in Eos-CRSwNP patients and was lower than non-Eos-CRSwNP patients (F=2.780,P<0.05), and was negatively correlated with ECP (r=-0.326,P<0.05). Compared with controls, Eos-CRSwNP patients in CRSsNP patients and non-Eos-CRSwNP patients exhibited a significantly lower frequency of CD4+CD25+Foxp3+Treg cells (F=13.140, all P<0.01). The expression of Notch-l and Jagged-l in Eos-CRSwNP was significantly higher than that of the controls, CRSsNP patients and non-Eos-CRSwNP patients (F=5.953/F=6.380, P<0.05). In the nasal polyp group, the expression of Notch-l and Jagged-l showed significantly negative correlation with Foxp3 (r=-0.611/-0.346, all P<0.05), and positive correlation with Th2 cytokines (IL-4, IL-5, IL-13) and ECP, respectively (r=0.781/0.459,0.621/0.601,0.605/0.490,0.464/0.668, all P<0.05). There was no significant difference in the expression of receptor and ligand of the other Notch pathway among the groups. Conclusion: Abnormal activation of Notch-l/Jagged-l pathway may be involved in decreasing Treg ratio in Eos-CRSwNP, thereby promoting Th2 inflammatory response and Eosinophil infiltration.

[Expression and cellular provenance of interleukin 17A in non-eosinophilic chronic rhinosinusitis with nasal polyps]

Objective: To investigate the expression and cellular provenance of interleukin 17A (IL-17A) in non-eosinophilic chronic rhinosinusitis with nasal polyps (nECRSwNP), and to analyze the possible reasons for its different expression. Methods: Samples were collected from 14 patients with eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) and 28 patients with nECRSwNP, who underwent functional endoscopic sinus surgery in the Third Affiliated Hospital of Sun Yat-sen University from January 2017 to May 2018, including 33 males and 9 females, with the age ranging from 18 to 65 years old. Enzyme linked immune sorbent assay (ELISA) and flow cytometry were used to investigate the expression and cellular origins of IL-17A in the nasal tissue of ECRSwNP and nECRSwNP groups. Then the difference of quantity and differentiation ability of the major cells producing IL-17A between ECRSwNP and nECRSwNP groups were analyzed by flow cytometry. Finally, the expressions of IL-6, transforming growth factor-β(TGF-β), and IL-23, which were considered as the important factors in promoting Th17/Tc17 differentiation in CRSwNP and their correlation with IL-17A, were analyzed by ELISA. Statistical analysis was performed using IBM SPSS 20. Results: The IL-17A protein levels and IL-17A(+)lymphocyte percentages were higher in nECRSwNP group compared with that of the ECRSwNP group (158.56 (167.76) pg/ml (M(QR)) vs. 9.42 (11.33) pg/ml, 10.21%±1.54% (x±s) vs. 3.93%±0.80%, Z=2.95, t=3.62, all P<0.01). Tc17 cells (CD8(+)T cells producing IL-17A) and Th17 cells (CD4(+)T cells producing IL-17A) were major IL-17A producers in both ECRSwNP and nECRSwNP group. Further analysis revealed that there was no significant difference in quantity of CD8(+)and CD4(+)T cells between ECRSwNP and nECRSwNP group, but the differentiation ability about CD8(+)and CD4(+)T cells differentiating into Tc17 and Th17 in nECRSwNP group was stronger than that in ECRSwNP. The high expressions of IL-6 and TGF-β, which were considered as the important factors in promoting Th17/Tc17 differentiation were also found in nECRSwNP group compared with ECRSwNP (56.07 (234.25) pg/ml vs. 8.27 (12.51) pg/ml, (5.44±0.34) pg/ml vs. (4.17±0.22) pg/ml, Z=2.426, t=2.29, all P<0.05). But the difference in expression of IL-23 was not significant difference between the two groups. Moreover, the expression of IL-17A showed significantly positive correlation with IL-6 (r=0.615, P=0.009). No positive correlation between IL-17A and TGF-β or IL-23 was observed. Conclusions: The expression of IL-17A in nasal mucosa of nECRSwNP patients is significantly higher than that of ECRSwNP, which is due to the increase of expression and differentiation of Tc17/Th17 cells. IL-17A shows positive correlation with IL-6 in CRSwNP, which is the important factor in promoting Th17/Tc17 differentiation.

Case Report of an 18 Year Old Girl with Solid Pseudo-papillary Tumor of Pancreas

Solid Pseudo-papillary Tumor (SPT) of the pancreas is a rare tumor which typically affects young women without any significant clinical symptoms. Solid Pseudopapillary Tumor usually shows an indolent behavior and only rare cases recur and/or metastasize after complete resection. Here is a case report of 18 years old girl who presented to our centre with complaints of severe epigastric pain and underwent pancreatic parenchyma saving surgery for a large pancreatic head mass. In conclusion, Solid Pseudo-papillary Tumor being a large tumor possess a low malignant potential in which R0 resection has excellent prognosis.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Awareness and willingness towards pre-exposure prophylaxis against HIV infection among individuals seeking voluntary counselling and testing for HIV in Taiwan: a cross-sectional questionnaire survey

OBJECTIVES

We aimed to investigate the awareness and willingness towards pre-exposure prophylaxis (PrEP) among individuals seeking voluntary counselling and testing (VCT) for HIV in Taiwan, where PrEP is currently not reimbursed by the insurance.

METHODS

Between April and October 2016, a questionnaire interview was conducted among VCT clients to inquire about the attitudes towards PrEP against HIV infection. Multivariate logistic regression analysis was performed to identify the associated factors with willingness to initiate PrEP.

RESULTS

During the 6-month period, 1173 VCT clients (99.8%) completed the interviews, with 67.4% being homosexual or bisexual male. While 67.2% of the clients knew of postexposure prophylaxis, 40.2% heard of PrEP. Overall, 546 clients (46.5%) were willing to initiate PrEP and 89.5% of them would choose event-driven PrEP. In multivariate analysis, male gender (OR 1.796; 95% CI 1.165 to 2.768), full-time job (OR 1.354; 95% CI 1.052 to 1.742), one-night stand (OR 1.374; 95% CI 1.043 to 1.810), having casual sex partners within 3 months (OR 1.329; 95% CI 1.031 to 1.714), condomless anal sex (OR 1.405; 95% CI 1.122 to 1.878) and ever having chemsex or attending a drug party in the past 1 year (OR 2.571; 95% CI 1.541 to 4.287), regular screening for HIV infection (OR 1.321; 95% CI 1.021 to 1.711) and knowledge of PrEP (OR 1.504; 95% CI, 1.159 to 1.953) were associated with willingness to initiate PrEP.

CONCLUSIONS

Understanding the willingness to initiate PrEP against HIV among the VCT clients in Taiwan, which was associated with male gender, risky sexual behaviours and awareness of PrEP, will help inform the implementation of PrEP programme.

[Psychopathological characteristics in patients with deviation of nasal septum: a preliminary analysis]

Objective: To investigate the psychopathological characteristics in patients with deviation of nasal septum. Methods: Between May 2015 and December 2015, fourty-four patients with deviated nasal septum and 37 patients with vocal cord polyp as control were included in this study. Psychological characteristics were evaluated by a series of questionnaire instruments including symptom checklist-90 (SCL-90), self-rating depression scale (SDS) and self-rating anxiety scale (SAS). Visual analogue scale (VAS) and rhinomanometry through front nostril were used to evaluate nasal symptom. The correlation between psychological characteristics and nasal symptom was evaluated. SPSS 20.0 software was used to analyze the data. Results: The SCL-90 score in nasal septal deviation group was 130.4±48.3. The total score and total average score of SCL-90 had no significant difference between nasal septal deviation group and the Chinese standard or control group(t value was 0.469, 0.112, 1.575, 1.564, respectively, all P>0.05). The scores of somatization, depression and anxiety factors in nasal septal deviation group were higher than control group (t value was 2.380, 2.133, 1.969, respectively, all P<0.05). The proportion of positive patients in these three factors between nasal septal deviation group and control group had significant differences (χ² value was 11.585, 9.610, 5.429, respectively, all P<0.05). The scores of SDS and SAS in nasal septal deviation group were 46.0±10.6 and 43.0±10.2, which were higher than that in the Chinese standard and control group (t value was 5.342, 6.236, 1.476, 3.013, respectively, all P<0.05). There were 9 patients companying with depression or anxiety (20.5%, 20.5%, respectively) and 5 patients companying with depression and anxiety in nasal septal deviation group (11.4%). There were positive correlation not only between the scores of SDS and the depression factor of SCL-90 but also between the scores of SAS and the anxiety factor of SCL-90 (Z=0.415, P=0.005, Z=0.445, P=0.002, respectively). The scores of SDS and SAS had positive correlation (Z=0.392, P=0.008). The VAS score of nasal obstruction was 6.0±3.2. The rhinomanometry in inspiratory and expiratory phase were (0.202±0.140) kPa·S/cm³ and (0.230±0.161) kPa·S/cm³. Besides the positive correlation between the rhinomanometry in inspiratory phase and SDS (Z=0.332, P=0.045), the psychological scores, including SCL-90 score, depression, anxiety factors score, SAS and SDS, had no correlation with VAS scores and rhinomanometry (r value was -0.030, -0.052, -0.026, 0.107, 0.185, 0.066, 0.160, 0.203, respectively, all P>0.05). Conclusions: High prevalence of depression and anxiety is found in patients with deviation of nasal septum. The SCL-90 score is consistent with SDS and SAS. Besides the positive correlation between the rhinomanometry in inspiratory phase and SDS, the psychological scores (SCL-90 score, depression, anxiety factors score, SAS and SDS) have no correlation with VAS score and rhinomanometry.

[Mutant Rad50 enhances killing effects of radiation on nasopharyngeal carcinoma cell line CNE1]

Objective: To investigate the killing effects of radiation and mutant Rad50 transfection on human nasopharyngeal carcinoma cell line CNE1. Methods: The experimental groups included: control group, Ad-Rad50-GFP group, Ad-EGFP group, irradiation group, Ad-Rad50-GFP combined with irradiation group, and Ad-EGFP combined with irradiation group. CNE1 cells were transfected with recombinant adenoviral vector Ad-Rad50-GFP carrying mutant Rad50 gene. The expressions of Mre11, Rad50, Nbs1, and relevant constituents composing MRN complex were detected by Western Blot. Neutral comet assay was used to detect the effect of mutant Rad50 on restoration process of DNA damage. Cell growth curve was used to evaluate the growth inhibition of CNE1 by mutant Rad50 and radiation. Results: Expressions of Mre11, Rad50, and Nbs1 in cells of Ad-Rad50-GFP group were less significantly than those in control group when irradiation was completed (0.48 vs 0.62, 0.42 vs 0.5, and 0.53 vs 0.69, respectively, P<0.05) and 24 hours after irradiation (0.41 vs 0.69, 0.46 vs 0.58, and 0.34 vs 0.78, respectively, P<0.05). The mean tail moment (MTM) in Ad-Rad50-GFP plus irradiation group was higher than that in irradiation group when irradiation was completed (16.06 vs 14.8, P<0.05), 24 hours after irradiation (58.23 vs 15.89, P<0.05) and 48 hours after irradiation: (45.12 vs 11.42, P<0.05). Seven days after irradiation, the cells in Ad-Rad50-GFP plus irradiation group was less than those in control group or irradiation group (both P<0.05). Conclusion: Mutant Rad50 enhances killing effects of radiation on nasopharyngeal carcinoma cell line CNE1.

Increasing incidence of recent hepatitis C virus infection among persons seeking voluntary counselling and testing for HIV and sexually transmitted infections in Taiwan

OBJECTIVES

The incidence of hepatitis C virus (HCV) infection among HIV-negative men who have sex with men (MSM) is rarely investigated in the Asia-Pacific region. We aimed to estimate the incidence rate of and factors associated with recent HCV infection among the clients seeking voluntary counselling and testing (VCT) services for HIV in Taiwan.

METHODS

During 2006-2013, 12 143 clients sought VCT services for HIV. Clients with subsequent follow-up tests at an interval of 6 months or longer were included to estimate the incidence rate of HCV seroconversion. Phylogenetic analysis of HCV sequences from VCT clients and HIV-positive patients was performed.

RESULTS

The overall HCV seroprevalence at baseline was 0.3%. Of 2150 clients testing negative for anti-HCV antibody at baseline with a total of 5074.99 person-years of follow-up (PYFU), 17 (0.8%) developed HCV seroconversion, leading to an overall incidence rate of 3.35 per 1000 PYFU (95% CI 1.76 to 4.94), which increased from 2.28 (95% CI 0.05 to 4.51) in 2006-2009, to 3.33 (95% CI 0.86 to 5.80) in 2010 to 2011 and 4.94 per 1000 PYFU (95% CI 0.99 to 8.99) in 2012-2013; the incidence of early syphilis increased from 11.91 to 13.28 and 31.78 per 1000 PYFU in the three corresponding periods. In multivariate analysis, having HIV-positive partners (adjusted HR (AHR) =3.756; 95%CI 1.180 to 11.955) and developing a rapid plasma reagin titre of 4 or greater (AHR=9.978; 95% CI 1.550 to 64.233) were significantly associated with HCV seroconversion.

CONCLUSIONS

An increasing trend of recent HCV infection occurs among individuals seeking VCT services in Taiwan. Having HIV-positive partners and having syphilis are independently associated with recent HCV seroconversion.

Transmitted drug resistance of HIV-1 strains among individuals attending voluntary counselling and testing in Taiwan

BACKGROUND

Genotypic drug resistance testing for HIV-1 has been integrated into voluntary counselling and testing (VCT) programmes to investigate the trends of transmitted drug resistance (TDR), including integrase mutations, among individuals with recent or chronic HIV infections in Taiwan.

METHODS

Between 2006 and 2014, 745 of 21 886 subjects (3.4%) tested HIV positive in the VCT service. The BED assay was used to identify recent HIV infections. Genotypic resistance mutations were interpreted using the WHO 2009 list. Integrase resistance mutations were analysed using the Stanford HIV Drug Resistance Database.

RESULTS

Three-hundred-and-sixty (48.3%) patients were recently infected with HIV-1. Of 440 patients linked to HIV care with analysable reverse transcriptase and protease genes, 49 (11.1%) were infected with HIV-1 harbouring at least one resistance-associated mutation (RAM). The prevalence of TDR to NRTIs, NNRTIs and PIs was 4.1%, 6.4% and 2.3%, respectively. TDR prevalence did not change significantly during the study period. CD4 counts ≤500 cells/mm(3) and hepatitis B surface antigen positivity were independent factors associated with acquiring drug-resistant HIV. The prevalence of integrase mutations was 3.2%. Among the seven major integrase mutations (T66I, E92Q, G140S, Y143C/H/R, S147G, Q148H/K/R and N155H), only one strain harbouring the Q148R mutation was detected. We found no statistically significant difference between patients with chronic infection and those with recent infection in the prevalence of drug-resistant mutations to any of the four classes of antiretroviral agents.

CONCLUSIONS

The prevalence of TDR of HIV-1 strains to available antiretroviral agents is moderately high, but transmission of HIV-1 with drug-resistant mutations remains stable in Taiwan.

Abnormal foraging behavior induced by sublethal dosage of imidacloprid in the honey bee (Hymenoptera: Apidae)

Although sublethal dosages of insecticide to nontarget insects have never been an important issue, they are attracting more and more attention lately. It has been demonstrated that low dosages of the neonicotinoid insecticide imidacloprid may affect honey bee, Apis mellifera L., behavior. In this article, the foraging behavior of the honey bee workers was investigated to show the effects of imidacloprid. By measuring the time interval between two visits at the same feeding site, we found that the normal foraging interval of honey bee workers was within 300 s. However, these honey bee workers delayed their return visit for > 300 s when they were treated orally with sugar water containing imidacloprid. This time delay in their return visit is concentration-dependent, and the lowest effective concentration was found to be 50 microg/liter. When bees were treated with an imidacloprid concentration higher than 1,200 microg/liter, they showed abnormalities in revisiting the feeding site. Some of them went missing, and some were present again at the feeding site the next day. Returning bees also showed delay in their return trips. Our results demonstrated that sublethal dosages of imidacloprid were able to affect foraging behavior of honey bees.

T lymphocyte mediated lysis of mitomycin C treated Tenon's capsule fibroblasts

AIMS

To evaluate the effect of T cell co-culture on mitomycin C treated and untreated Tenon's capsule fibroblasts.

METHODS

IL-2 dependent allogeneic T cells were incubated over a monolayer of mitomycin C treated or control fibroblasts. Fibroblast numbers were evaluated by direct counts using phase contrast microscopy. To determine whether T cell mediated lysis was a consequence of MHC mismatch, co-culture experiments were repeated with autologous T cells. The effect of Fas receptor blockade was established by co-incubation with a Fas blocking (M3) antibody.

RESULTS

T cell co-culture resulted in a dramatic reduction in fibroblast survival compared to mitomycin C treatment alone (p = 0.032). T cell killing required fibroblast/lymphocyte cell to cell contact and was observed in both allogeneic and autologous co-culture experiments. Fas blocking antibodies did not significantly inhibit T cell killing (p = 0.39).

CONCLUSION

T cells augment mitomycin C treated fibroblast death in vitro. Similar mechanisms may contribute to the cytotoxic effect of mitomycin C in vivo and account for the largely hypocellular drainage blebs that are observed clinically.

PRA1 inhibits the extraction of membrane-bound rab GTPase by GDI1

Rab is a family of small Ras-like GTPases regulating intracellular vesicle transport. We have previously reported that prenylated Rab acceptor or PRA1 interacts with Rab GTPases and vesicle-associated membrane protein (VAMP2). Structural prediction programs suggest that PRA1, with its two extensive hydrophobic domains, is likely to be an integral membrane protein. However, subcellular fractionation and immunocytochemical analyses indicated that PRA1 is localized both in the cytosol and tightly associated with the membrane compartment. The membrane-bound form can be partially extracted with physiological buffer and urea, suggesting that PRA1 is an extrinsic membrane protein. Deletion of the carboxyl-terminal domain resulted in a protein that behaved as an integral membrane protein, indicating that this domain plays an essential role in maintaining PRA1 in a soluble state. PRA1 can also bind weakly to GDP dissociation inhibitor (GDI), a protein involved in the solubilization of membrane-bound Rab GTPases. Addition of PRA1 inhibited the extraction of membrane-bound Rab3A by GDI, suggesting that membrane localization of Rab GTPases is dependent on the opposing action of PRA1 and GDI. The binding of Rab and VAMP2 to PRA1 is mutually exclusive such that Rab3A can displace VAMP2 in a preformed VAMP2-PRA1 complex.

NOS inhibitors decrease hypoxia-induced ATP reductions in respiring cerebrocortical slices

BACKGROUND

Excess neuronal nitric oxide (NO) production might cause adenosine triphosphate loss and cellular damage in hypoxic brain parenchyma. 31P nuclear magnetic resonance spectroscopy was used to study hypoxic intracellular responses in perfused respiring cerebrocortical slices, in which NO scavenging by hemoglobin is absent, during NO synthase blockade and NO augmentation.

METHODS

Adenosine triphosphate concentrations were monitored at 4.7 Tesla in respiring slices before, during, and after 60 min of hypoxia (oxygen tension < 5 mmHg). Slices were not treated or were pretreated with 27 microM L-nitroarginine methyl ester (L-NAME), 27 microM 7-nitroindozole (7-NI), or 27 microM L-nitroarginine. Nitrotyrosine:tyrosine ratios of slice extracts were measured using high-performance liquid chromatography. Cresyl violet-stained sections (2 microm) from random slices were examined histologically.

RESULTS

After 60 min of hypoxia, adenosine triphosphate decreased to < or = 3, < or = 3, 65 +/- 6, and 25 +/- 4% of control in slices that were untreated or treated with L-nitroarginine, L-NAME, and 7-NI, respectively. After 120 min of hyperoxic recovery, adenosine triphosphate levels returned to control values in slices pretreated with L-NAME and 7-NI, but to only 30% of control in untreated or L-nitroarginine-treated slices. Nitric oxide donors administered during posthypoxic recovery partially antagonized the adenosine triphosphate recovery found with L-NAME and 7-NI. Nitric oxide synthase activity in slice homogenates, assayed via conversion of L-arginine to citrulline, was < or = 2% of control after all inhibitory treatments. The nitrotyrosine:tyrosine ratio increased by 52% in slices treated with 7-NI and by 200-300% in all other groups. Pretreatment with L-NAME and 7-NI reduced histologic evidence of cell swelling.

CONCLUSION

Neuronal NO is associated with rapid adenosine triphosphate reductions and peroxynitrite formation in acutely hypoxic cerebrocortical slices.

Occupational therapists' expectations in rehabilitation following stroke: sources of satisfaction and dissatisfaction

OBJECTIVE

The purpose of this study was to gain understanding of the satisfactions and dissatisfactions in the work of occupational therapists with clients after stroke.

METHOD

Data consisted of narrative descriptions by 32 therapists of especially satisfying and dissatisfying experiences in practice. Phenomenology and grounded theory strategies were used for the study design and data analysis.

RESULTS

"Expectation" emerged as the core meaning of occupational therapy in stroke rehabilitation. Strong satisfaction was expressed when therapist-informants believed that they had fulfilled their expectations for clients to achieve the following: (a) maximum neuromuscular and functional recovery in affected upper extremities; (b) independence in daily activities; and (c) return to living in the community. Major sources of informants' dissatisfactions were reaching the "plateau" stage of neurological recovery, disagreement between therapist expectations and client and family member expectations, and working with clients perceived as poorly motivated.

CONCLUSION

American ideologies about the value of hard work, independence, and self-sufficiency appear to strongly shape therapists' expectations, satisfaction, and dissatisfaction in stroke rehabilitation. For occupational therapists, a tension may exist between the idealism of their therapeutic expectations and the realities of stroke recovery as it is experienced within the context of clients' ongoing lives.

An SRRC elliptically polarizing undulator prototype to examine mechanical design feasibility and magnetic field performance

In this work, a 1 m long Sasaki-type elliptically polarizing undulator (EPU) prototype with 5.6 cm period length is used to examine the mechanical design feasibility as well as magnetic field performance. The magnetic field characteristics of the EPU5.6 prototype at various phase shifts and gap motion are described. The field errors from mechanical tolerances, magnet block errors, end field effects and phase/gap motion effects are analysed. The procedures related to correcting the field with the block position tuning, iron shimming and the trim blocks at both ends are outlined.

Effects of magnets with non-unit magnetic permeability on an elliptically polarizing undulator

This study employs the three-dimensional magnetostatic code TOSCA to assess numerically the effects of NdFeB magnets with non-unit magnetic permeability on an elliptically polarizing undulator. A reduction of a few percent of the on-axis magnetic field strength is predicted. In addition, a deviation of +/-100 G cm uncompensated dipole steering is predicted in a phase shift of 180 degrees for the elliptically polarizing undulator EPU5.6 (having a period length of 56 mm) at the minimum gap of 18 mm, which is related primarily to the configuration of the device end scheme. Results presented herein demonstrate that implementing an active compensation mechanism is a prerequisite for minimizing the orbit distortion during phase-shift adjustment, particularly for operating such a polarizing undulator in a third-generation machine having a median energy similar to that of the 1.5 GeV storage ring at SRRC.

Spectral properties of the polarizing devices at SRRC

User requirements at SRRC for high-brilliance synchrotron light in various polarization states will be fulfilled in the near future by the implementation of two types of polarizing devices in the storage ring: the elliptically polarizing undulator (EPU) and the elliptically polarized bending magnet (EPBM). The EPBM provides a broadband polarized spectrum up to the soft X-ray range with rapid alternation of the left and right helicities. The EPU, which has a magnetic period length of 56 mm, generates a high-brilliance harmonic spectral intensity in the range 80-1400 eV with abundant polarization states, including circular ones. The optimal merit flux is evaluated for the operation of these two polarizing devices in the SRRC 1.5 GeV storage ring. The available polarization states are also surveyed.

Fructose-1,6-bisphosphate preserves adenosine triphosphate but not intracellular pH during hypoxia in respiring neonatal rat brain slices

BACKGROUND

Fructose-1,6-bisphosphate (FBP) sometimes provides substantial cerebral protection during hypoxia or ischemia. 31P/1H nuclear magnetic resonance spectroscopy of cerebrocortical slices was used to study the effects of FBP on hypoxia-induced metabolic changes. In addition, 13C-labeled glucose was administered and 13C nuclear magnetic resonance spectroscopy was used to search for FBP-induced modulations in glycolysis and the pentose-phosphate pathway.

METHODS

In each experiment, 80 slices (350 microm) obtained from ten 7-day-old Sprague-Dawley rat litter mates were placed together in a 20-mm nuclear magnetic resonance tube, perfused, and subjected to 30 min of hypoxia (PO2 < 3 mmHg). Nine experiments were performed, with n = 3 in each of three groups: (1) no treatment with FBP; (2) 60 min of prehypoxia treatment with FBP (2 mM); and (3) 60 min of posthypoxia treatment with FBP (2 mM). 31P/1H Interleaved nuclear magnetic resonance spectra at 4.7 T provided average adenosine triphosphate, intracellular pH, and lactate. Cresyl violet stains of random slices taken at predetermined time points were studied histologically. Some experiments had [2-13C]glucose in the perfusate. Slices from these studies were frozen for perchloric acid extraction of intracellular metabolites and studied with high-resolution 13C nuclear magnetic resonance spectroscopy at 11.75 T.

RESULTS

With no pretreatment with FBP, hypoxia caused an approximately 50% loss of adenosine triphosphate, an approximately 700% increase in lactate, and a decrease in intracellular pH to approximately 6.4. Pretreatment with FBP resulted in no detectable loss of adenosine triphosphate, no increase in lactate, and minimal morphologic changes but did not alter decreases in intracellular pH. 13C Nuclear magnetic resonance spectra of extracted metabolites showed that pretreatment caused accumulation of [1-13C]fructose-6-phosphate, an early pentose-phosphate pathway metabolite. Posthypoxic treatment with FBP had no effects compared with no treatment.

CONCLUSIONS

During severe hypoxia, pretreatment with FBP completely preserves adenosine triphosphate and almost completely preserves cell morphology but does not alter hypoxia-induced decreases in intracellular pH. Pretreatment also substantially augments the flux of glucose into the pentose-phosphate pathway.

Effect of brain, body, and magnet bore temperatures on energy metabolism during global cerebral ischemia and reperfusion monitored by magnetic resonance spectroscopy in rats

To record brain temperature for comparison with rectal and temporalis muscle temperatures in preliminary studies before MR spectroscopy experiments, a thermistor was inserted into the basal ganglia in eight anesthetized, ventilated, and physiologically monitored rats. The rats were placed in an MR spectrometer and subjected to 60 min of global cerebral ischemia and 2 h of reperfusion without radiofrequency (RF) pulsing. Body temperature was maintained at 37.5-38.0 degrees C (normothermia) or 36.5-37.0 degrees C (mild hypothermia). Brain temperature during ischemia, which dropped to 31.9 +/- 0.3 (hypothermia) and 33.6 +/- 0.5 degrees C (normothermia), correlated with temporalis muscle temperature (r2 = 0.92) but not with body or magnet bore temperature measurements. Ischemia reduced brain temperature approximately 1.7 degrees C in rats subjected to mild hypothermia (1 degree reduction of body temperature). Parallel MR spectroscopy experiments showed no significant difference in energy metabolites between normothermic and hypothermic rats during ischemia. However, the metabolic recovery was more extensive 20-60 min after the onset of reperfusion in hypothermic rats, although not thereafter (P < 0.05). Mild hypothermia speeds metabolic recovery temporarily during reperfusion but does not retard energy failure during global ischemia in rats.

The role of 20-hydroxyecdysone in stimulating DNA synthesis in corpora allata of the silkworm, Bombyx mori

Temporal changes in DNA synthesis were examined in the corpora allata of the silkworm Bombyx mori during the penultimate larval stadium. 5'-Bromo-2'-deoxyuridine (BrdU) labeling revealed that allatal DNA synthesis rose early in the stadium, peaking at about 2% of corpus allatum (CA) cells 24 hr after ecdysis. This corresponded to a rising phase of the ecdysteroid titer reported previously. DNA synthesis declined to a nearly undetectable level 1 day later. In larvae fed on leaves coated with 20-hydroxyecdysone (20E), the number of BrdU-labeled cells increased continuously after the normal peak and reached about 8% of CA cells at the end of the stadium. However, total count of CA cells from whole-mount monolayers and colchicine treatment indicated that, regardless of DNA content, CA cells did not divide. To determine if the rise in 20E was responsible for the onset of allatal DNA synthesis, we have established an organ culture system to support de novo DNA synthesis in vitro. The number of BrdU-labeled cells increased with increasing 20E concentration between 0.1 and 0.5 microg ml-1 in the medium, corresponding well to the rising 20E titer in the hemolymph. The level of DNA synthesis in culture was further elevated when 20% hemolymph was added together with 20E, suggesting that other direct stimulatory factors for allatal DNA synthesis may also exist in the hemolymph.

Adult rat brain-slice preparation for nuclear magnetic resonance spectroscopy studies of hypoxia

BACKGROUND

When perfused neonatal brain slices are studied ex vivo with nuclear magnetic resonance (NMR) spectroscopy, it is possible to use 31P detection to monitor levels of intracellular adenosine triphosphate (ATP), cytosolic pH, and other high-energy phosphates and 1H detection to monitor lactate and glutamate. Adult brain slices of high metabolic integrity are more difficult to obtain for such studies, because the adult cranium is thicker, and postdecapitation revival time is shorter. A common clinical anesthesia phenomenon--loss of temperature regulation during anesthesia, with surface cooling and deep hypothermia, was used to obtain high-quality adult rat cerebrocortical slices for NMR studies.

METHODS

Spontaneously breathing adult rats (350 g), anesthetized with isoflurane in a chamber, were packed in ice and cooled until rectal temperatures decreased to approximately 30 degrees C. An intraaortic injection of heparinized saline at 4 degrees C further cooled the brain to approximately 18 degrees C. Slices were obtained and then recovered at 37 degrees C in oxygenated medium. Interleaved 31P/1H NMR spectra were acquired continually before, during, and after 20 min of no-flow hypoxia (PO2 approximately 0 mmHg). Histologic (Nissl stain) measurements were made from random slices removed at different times in the protocol. Three types of pretreatment were compared in no-flow hypoxia studies. The treatments were: (1) hyperoxia; (2) hypercapnia (50% CO2); and (3) hypoxia, which was accomplished by washing the slices with perfusate equilibrated with 100% N2 and maintaining a 100% N2 gas flow in the air space above the perfusate.

RESULTS

During hyperoxia, 31P NMR metabolite ratios were identical to those seen in vivo in adult brains, except that, in vitro, the Pi peak was slightly larger than in vivo. A lactate peak was seen in in vitro 1H spectra of slices after metabolic recovery from decapitation, although lactate is barely detectable in vivo in healthy brains. The in vitro lactate peak was attributed to a small population of metabolically impaired cells in an injury layer at the cut edge. NMR spectral resolution from the solenoidal coil exceeded that obtained in vivo in surface coil experiments. Phosphocreatine and ATP became undetectable during oxygen deprivation, which also caused a three- to sixfold increase in the ratio of lactate to N-acetyl-aspartate. Within experimental error, all metabolite concentrations except pHi recovered to control values within 2 h after oxygen restoration. Nissl-stained sections suggested that pretreatment with hypercapnia protected neurons from cell swelling during the brief period of no-flow oxygen deprivation.

CONCLUSIONS

Perfused, respiring adult brain slices having intact metabolic function can be obtained for NMR spectroscopy studies. Such studies have higher spectral resolution than can be obtained in vivo. During such NMR experiments, one can deliver drugs or molecular probes to brain cells and obtain brain tissue specimens for histologic and immunochemical measures of injury. Important ex vivo NMR spectroscopy studies that are difficult or impossible to perform in vivo are feasible in this model.

19F NMR calcium changes, edema and histology in neonatal rat brain slices during glutamate toxicity

Respiring neonatal cerebrocortical slices (350 microns thick), loaded with the free calcium indicator 5F-BAPTA, were perfused in a 20-mm-diameter glass NMR tube with oxygenated artificial CSF, exposed to extracellular glutamate and studied at 4.7 Tesla with 19F NMR spectroscopy. 31P/1H NMR spectra, obtained concurrently, were used to assess slice integrity from determinations of intracellular pH, ATP, PCr, lactate and N-acetylaspartate. 60-min periods were induced of recoverable and nonrecoverable glutamate toxicity-defined from changes in NMR metabolites. In other NMR studies, where 5F-BAPTA was not used, metabolic toxicity was modulated by three glutamate receptor antagonists: dizocilpine, NBQX and kynurenic acid. Outcome measurements were made of edema, determined invasively in isolated slices from % swelling and water content and from histological changes in Nissl stains of slice sections. Edema was (1) detectable in all slices within minutes after onset of glutamate exposure, though never in untreated control slices, and (2) modulated differently by dizocilpine, NBQX and kynurenate. Correlations were observed between edema and NMR decreases in PCr and ATP. Nissl stains of sections from slices treated with the most protective agent, dizocilpine, showed preservation of neuronal processes. As was expected in 7-day-old rats with immature NMDA receptors, 19F NMR spectroscopy revealed only small increases in free intracellular calcium ([Ca2+]i). These occurred late during glutamate exposure and reversed early during glutamate washout. The studies demonstrate that it is possible to study correlations between repeated noninvasive NMR spectra in ensembles of brain slices and invasive measures of early cellular responses.

Modulation of glutamate-induced intracellular energy failure in neonatal cerebral cortical slices by kynurenic acid, dizocilpine, and NBQX

The severity and rapidity of acute, glutamate-induced energy failure were compared in live cerebral cortical slices. In each experiment 80 live cerebral cortical slices (350 microns thick) were obtained from neonatal Sprague-Dawley rats, suspended and perfused in a nuclear magnetic resonance (NMR) tube, and studied at 4.7 T with interleaved 31P/1H NMR spectroscopy. NMR spectra, obtained continually, were determined as 5-min averages. Slices were perfused for 60 min with artificial cerebrospinal fluid (ACSF) containing either glutamate alone or glutamate mixed with one of three glutamate-receptor antagonists: kynurenate, dizocilpine (MK-801), and 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo(F)quinoxaline (NBQX). Dose-dependent decreases in high-energy phosphates were studied during glutamate exposure (0.5 to 10 mM), with and without antagonist protection. Energy recovery after glutamate exposures was measured during a 60-min washout with glutamate-free, antagonist-free ACSF. Reversible and irreversible energy failures were characterized by changes in intracellular pH, and by changes in relative concentrations of ATP, phosphocreatine (PCr), and inorganic phosphate. No changes were observed in intracellular levels of N-acetylaspartate and lactate. Some special studies were also done using R-(-)-2-amino-5-phosphonovaleric acid (100 microM) and tetrodotoxin (1 mM) to examine glutamate receptor specificity in this tissue model. Dizocilpine (150 microM) best ameliorated the energy failure caused by 2.0 mM glutamate. With dizocilpine the maximum ATP decrease was only 6 +/- 5%, instead of 35 +/- 7%.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of edema by dizocilpine, kynurenate, and NBQX in respiring brain slices after exposure to glutamate

Brain edema caused by glutamate excitotoxicity was studied in well oxygenated neonatal cerebrocortical brain slices (350 mu thick). Slices exposed to 60 minutes of 2 mM glutamate, with or without glutamate antagonists (dizocilpine, kynurenate, or NBQX), were allowed to recover for 60 minutes. The protocol was identical to that in noninvasive multinuclear NMR spectroscopy studies (31P/1H/19F) of live slices. Percent water and swelling were determined invasively in isolated slices by wet and dry weight measurements before and after glutamate exposure. Edema was detectable within minutes in all experiments with glutamate exposures, but not in untreated control slices. Dizocilpine, kynurenate, and NBQX differently affected swelling, which correlated with PCr and ATP loss in separate NMR studies. Synaptic glutamate receptor activation appears to initiate events causing both edema and energy failure. Multiple glutamate receptor types seem to be involved. No glutamate antagonist provided greater protection against both edema and energy loss than dizocilpine. Dizocilpine might also block voltage-dependent Na+ channels, and provide protection via mechanisms other than NMDA-receptor dependent channel antagonism.

Relationship between extracellular neurotransmitter amino acids and energy metabolism during cerebral ischemia in rats monitored by microdialysis and in vivo magnetic resonance spectroscopy

The time-course of changes in extracellular glutamate and energy metabolism during 30 or 60 min of complete cerebral ischemia and 60-90 min of reperfusion was investigated by microdialysis and magnetic resonance spectroscopy in parallel groups of rats. During the first 10 min of ischemia, adenosine triphosphate (ATP) was completely depleted, and lactate increased 10-fold; after 30 min, intracellular pH had decreased to 6.33 +/- 0.11. ATP and lactate did not change further between 30 and 60 min of ischemia. Glutamate increased 30-fold between 10 and 30 min of ischemia and continued to increase in the 60-min ischemia group. After 30 min of reperfusion, glutamate had returned to pre-ischemic levels in both groups. The cellular energy state recovered within 50-60 min after 30 min of ischemia but never returned to more than 60% of baseline values after 60 min of ischemia. The continued increase in extracellular glutamate after total depletion of ATP suggests that glutamate release during ischemia is not entirely energy dependent. Ca(2+)-independent glutamate release and failure of energy-dependent glutamate re-uptake mechanisms may result in continued increase in extracellular glutamate. The rapid normalization of extracellular glutamate after 30 and 60 min of ischemia despite differences in the recovery of energy metabolism suggests that the glutamate levels were reduced by an energy-independent mechanism, such as diffusion into the restored circulation.

Effect of glucose and confluency on phosphorus metabolites of perfused human prostatic adenocarcinoma cells as determined by 31P MRS

A series of perfused cell 31P MRS studies were conducted using a well established human prostate adenocarcinoma cell line (DU 145) at different phases of growth, and exposed to varying glucose concentrations during growth. The spectral characteristics of perfused DU 145 cells were compared with the same cells grown in nude mice (xenografts). Perfused DU 145 cells had lower levels of inorganic phosphate and phosphocreative relative to in vivo nude mice xenografts. 31P MR spectra obtained from perfused cells at different phases of growth and exposed to varying glucose concentrations during grown suggest that increases in diphosphodiester levels are associated with high glucose concentrations and confluency. Perfused DU 145 cells grown in 5.5 mM glucose and harvested at log phase of growth best reflected the phosphorus MR spectra of the same cell line grown in nude mice.

Citrate alterations in primary and metastatic human prostatic adenocarcinomas: 1H magnetic resonance spectroscopy and biochemical study

The objectives of this study were to quantitatively verify the low levels of citrate previously observed in primary human prostatic adenocarcinomas and to determine whether citrate was further reduced in metastatic prostatic cancer. This was accomplished by comparison of citrate concentrations of DU 145 xenografts (a poorly differentiated human prostatic adenocarcinoma cell line grown in nude mice) with concentrations in primary human adenocarcinomas. Following in vivo 1H NMR studies of DU 145 xenografts, citrate concentrations of DU 145 xenografts and surgically removed primary prostatic adenocarcinoma tissue were determined by quantitative high resolution 1H NMR and enzymatic assay. The most significant findings of this study were that citrate concentrations in primary human adenocarcinomas (3.74 +/- 0.19 mumol/g wet weight) were significantly lower than those observed for normal and benign hyperplastic (BPH) prostatic tissues. Furthermore there was a further ten-fold reduction of citrate associated with DU 145 xenografts (0.31 +/- 0.028 mumole/g wet weight) compared with primary prostatic cancer. DU 145 xenografts also exhibited higher levels of uridine diphosphosugars and choline containing metabolites relative to primary prostatic adenocarcinomas. These findings support the hypothesis that citrate is low in primary prostatic cancer and further reduced in metastatic disease.

Site-directed mutagenesis and chemical modification of histidine residues on an alpha-class chick liver glutathione S-transferase CL 3-3. Histidines are not needed for the activity of the enzyme and diethylpyrocarbonate modifies both histidine and lysine residues

Each chick liver glutathione S-transferase CL 3 subunit contains three histidine residues: His142, His158 and His228. CL 3-3 can be inactivated by treating with diethylpyrocarbonate. The inactivation process is pH dependent and the pKa of the modified residue is 6.4. The second-order inhibition rate constant is 741 M-1min-1 at pH 7.0. Based on difference-spectrum and kinetic analysis, inactivation coincides with the modification of one histidine residue. However, hydroxylamine treatment of the diethylpyrocarbonate-modified enzyme only partially restored the activity (30-50%) of CL 3-3. By tryptic mapping and amino acid sequence analysis, His228 and Lys14 have been identified as the modified residues. Mutants with histidine to serine replacement (H142S and H158S) or C-terminal histidine deletion (des-H228) were constructed and over-expressed in Spodoptera frugiperda cells using a baculovirus system. The mutants are enzymically active. Furthermore, the des-H228 mutant can be inactivated by diethylpyrocarbonate. These results support the conclusion that histidines are not involved in the enzymic mechanism of CL 3-3.

Effect of dichloroacetate on recovery of brain lactate, phosphorus energy metabolites, and glutamate during reperfusion after complete cerebral ischemia in rats

The effects of dichloroacetate (DCA) on brain lactate, intracellular pH (pHi), phosphocreatine (PCr), and ATP during 60 min of complete cerebral ischemia and 2 h of reperfusion were investigated in rats by in vivo 1H and 31P magnetic resonance spectroscopy; brain lactate, water content, cations, and amino acids were measured in vitro after reperfusion. DCA, 100 mg/kg, or saline was infused before or immediately after the ischemic period. Preischemic treatment with DCA did not affect brain lactate or pHi during ischemia, but reduced lactate and increased pHi after 30 min of reperfusion (p < 0.05 vs. controls) and facilitated the recovery of PCr and ATP during reperfusion. Postischemic DCA treatment also reduced brain lactate and increased pHi during reperfusion compared with controls (p < 0.05), but had little effect on PCr, ATP, or Pi during reperfusion. After 30 min of reperfusion, serum lactate was 67% lower in the postischemic DCA group than in controls (p < 0.05). The brain lactate level in vitro was 46% lower in the postischemic DCA group than in controls (p < 0.05). DCA did not affect water content or cation concentrations in either group, but it increased brain glutamate by 40% in the preischemic treatment group (p < 0.05). The potential therapeutic effects of DCA on brain injury after complete ischemia may be mediated by reduced excitotoxin release related to decreased lactic acidosis during reperfusion.

Tolerance of low intracellular pH during hypercapnia by rat cortical brain slices: A 31P/1H NMR study

Metabolic tolerance of low intracellular pH (pH(i)) was studied in well-oxygenated, perfused, neonatal, rat cerebrocortical brain slices (350 microns thick) by inducing severe hypercapnia. In each of 17 separate experiments 80 brain slices (approximately 3.2 g wet weight) were suspended in an NMR tube, perfused with artificial CSF (ACSF), and studied at 4.7 T with 31P and 1H NMR spectroscopy. Spectra obtained every 5 min monitored relative concentrations of lactate or high-energy phosphate metabolites, from which pH(i) and extracellular pH were determined. Unperturbed slice preparations were metabolically stable for > 10 h, with no significant changes occurring in pHi, ATP, phosphocreatine (PCr), inorganic phosphate, or lactate. Different levels of hypercapnia were produced by sequentially perfusing slices with the following different ACSF batches, each having previously been equilibrated with a specific mixture of CO2 in oxygen: (a) 10% CO2, 15 min of perfusion; (b) 30% CO2, 15 min of perfusion; (c) 50% CO2, 15 min of perfusion; (d) 70% CO2, 30 min of perfusion; (e) 50% CO2, 15 min of perfusion; (f) 30% CO2, 15 min of perfusion; and (g) 10% CO2, 15 min of perfusion. At the completion of this protocol slices were again perfused with fresh ACSF that was equilibrated with a 95% O2/5% CO2 gas mixture. In each of five separate 1H and 31P experiments, brain slices were recovered within 2 h after termination of exposure to high CO2. The pHi was determined from measurements of the chemical shift difference between phosphoethanolamine and PCr, using a calibration curve obtained for our preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning and expression of a chick liver glutathione S-transferase CL 3 subunit with the use of a baculovirus expression system

Glutathione S-transferase CL 3 subunits purified from 1-day-old-chick livers were digested with Achromobacter proteinase I and the resulting fragments were isolated for amino acid sequence analysis. An oligonucleotide probe was constructed accordingly for cDNA library screening. A cDNA clone of 1342 bases, pGCL301, encoding a protein of 26209 Da was isolated and sequenced. Including conservative substitutions, this protein has 75-79% sequence similarity to other Alpha family glutathione S-transferases. The coding sequence of pGCL301 was inserted into a baculovirus vector for infection of Spodoptera frugiperda (SF9) cells. The expressed protein has a high relative activity with ethacrynic acid (47% of the specific activity with 1-chloro-2,4-dinitrobenzene). The enzyme has a subunit molecular mass of 25.2 +/- 1.2 kDa (by SDS/PAGE), a pI of 9.45 and an absorption coefficient A1%1cm of 13.0 +/- 0.5 at 280 nm.

The single cysteine residue on an alpha family chick liver glutathione S-transferase CL 3-3 is not functionally important

Chick liver glutathione S-transferase CL 3-3, expressed using a baculovirus system in Spodoptera frugiperda (SF9) cells, contains a single cysteine residue per subunit. This enzyme was modified with iodoacetamide. Amino acid analysis indicates that 0.85 +/- 0.10 cysteine residue was modified per enzyme subunit. GST CL 3-3 modified with iodo[14C]acetamide was further digested with trypsin and the isotope-labelled fragments were isolated. The fragment containing the cysteine residue accounts for 53% of the total labels. The S-carbaminomethylated protein retains the glutathione conjugating activity. Therefore, the cysteine residue is not essential for the enzymatic activity of CL 3-3.

Tolerance of low cerebral intracellular pH in rats during hyperbaric hypercapnia

BACKGROUND AND PURPOSE

Brain acidosis from cerebral ischemia is characterized by average intracellular pH levels of approximately 5.8-6.2, which appear in turn to worsen cellular injury. We report that the brain is not injured when hypercapnia is used to reduce intracellular pH to about 6.2 during adequate oxygenation. A hyperbaric chamber is needed to achieve intracellular pH values so low because inspired CO2 tensions must be increased to approximately 1 atm.

SUMMARY OF REPORT

Using in vivo phosphorus-31 and proton nuclear magnetic resonance spectroscopy, we measured brain intracellular pH and lactate concentration of rats inside a nonmagnetic polycarbonate chamber at a barometric pressure of 1,500 mm Hg. Intubated rats were ventilated with a 50% O2/50% CO2 gas mixture for specific times. All six rats ventilated for 15 minutes with CO2 tensions of approximately 750 mm Hg woke up without neurological impairment, despite a decrease in intracellular pH to about 6.2. Higher CO2 tensions and longer exposures resulted in cardiovascular collapse and sudden death, followed by the postmortem appearance of brain lactate.

CONCLUSIONS

Brain intracellular pH values near 6.2 can be induced briefly in vivo in ventilated rats without injury under hyperbaric hypercapnic conditions. If attempts are made to lower brain pH in vivo even further by increasing PCO2 beyond 750 mm Hg, mean arterial blood pressure and cerebral blood flow decrease to values incompatible with life.

Surface coil spectroscopic imaging: time and spatial evolution of lactate production following fluid percussion brain injury

Detailed temporal and spatial distributions of lactate production are presented for graded fluid-percussion brain injury in the rat. A one-dimensional proton spin-echo spectroscopic imaging (1D SESI) technique, performed with a surface coil, is presented and evaluated. This technique, which represents a practical compromise, provides spatially localized proton nuclear magnetic resonance (NMR) brain spectra from a series of small voxels (less than 0.15 cm3) in less than 10 min, thus enabling both spatial and temporal monitoring of lactate production. These high-resolution lactate maps are correlated with hyperintense regions observed in T2-weighted images taken 10 h after impact, which, in turn, correlate with histology. The data demonstrate that, following severe trauma there is delayed production and propagation of lactate to regions of the brain that are remote from the trauma site. The extent of lactate production depends on the severity of impact. More significantly, the data show that following severe trauma, local lactate concentrations exceed 15 mumol/g, the concentration that has been claimed as the threshold for brain injury. Therefore high lactate levels cannot be ruled out a priori as a possible factor in brain injury following severe head trauma.

Interleaved 1H and 31P spectroscopic imaging for studying regional brain injury

We present a new approach for in vivo localized spectroscopy which combines 1H and 31P one-dimensional spectroscopic imaging pulse sequences in an interleaved, time-shared manner using a surface coil. This approach was used to acquire metabolic information from a rat brain with regional ischemia at 4.7 Tesla. Spectra with very good signal-to-noise ratios, void of chemical shift artifacts, are obtainable from voxel sizes less than 0.3 cm3 in 40 min. Advantages and drawbacks of the proposed methodology are discussed.

Opiate-receptor antagonist improves metabolic recovery and limits neurochemical alterations associated with reperfusion after global brain ischemia in rats

Opiate-receptor antagonists improve behavioral, electrophysiologic and/or histologic outcome in various experimental models of central nervous system ischemia. To address the potential mechanism(s) by which opiate-receptor antagonists may exert their protective actions in cerebral ischemia, metabolic and biochemical changes were measured in brain of rats pretreated with the opiate-receptor antagonist nalmefene or vehicle and subjected to 60 min of global ischemia followed by 2 hr of reperfusion. 31P and 1H magnetic resonance spectroscopy were used to follow the metabolic changes during ischemia and reperfusion, after which brain tissue was frozen in situ. Biochemical assays included free fatty acids, thromboxane B2, ascorbate, vitamin E and amino acids. Nalmefene-treated animals showed more rapid and complete recovery of cellular bioenergetic state (as indicated by the phosphocreatine to inorganic phosphate ratio), tissue acidosis and lactate levels during reperfusion than placebotreated controls. Ischemia/reperfusion caused significant increases of fatty free acids and thromboxane, associated with significant decreases of ascorbate and glutamate; nalmefene pretreatment limited each of these changes. The degree of metabolic improvement as reflected by recovery of high energy phosphates and reduction of lactic acidosis were highly correlated with changes in tissue levels of arachidonate and glutamate. Thus, the beneficial effects of opiate-receptor antagonists in cerebral ischemia may be due, in part, to an ability to enhance metabolic recovery with associated, reduction in phospholipid hydrolysis and excitotoxin release.

31P magnetic resonance spectroscopy of animal uveal melanoma

Scleral surface coils were used to obtain in vivo magnetic resonance spectra (MRS) of Greene melanoma implanted in the rabbit uvea. Well-localized tumor spectra (4.7 Tesla) with good signal-to-noise ratios (S/N) were obtained from the tumor with a "single-pulse" sequence in less than 1 hour. Tumor localization was confirmed with one-dimensional spectroscopic imaging studies. Serial 31P spectra were obtained during tumor growth and after both optimal and suboptimal hyperthermia. Early 31P MRS change is correlated with tumor treatment response and preceded histologic evidence of cell destruction. Twenty-four to 48 hours after successful treatment, the inorganic phosphate/nucleoside triphosphate (NTP), and phosphomonoester/NTP ratios were significantly increased from 1.2 +/- 0.1 to 1.7 +/- 0.1 and 1.3 +/- 0.1 to 1.8 +/- 0.2, respectively. In contrast, untreated or ineffectively treated tumors showed little change. Interpretation of 31P MRS data in this animal uveal melanoma model after the first week was complicated by decreased S/N, increased contamination from contiguous tissues, ingrowth of fibroblasts, macrophages, and intratumor hemorrhage.

Absence of abundant binding sites for anesthetics in rabbit brain: an in vivo NMR study

Using magnetic resonance spectroscopy, the authors tested whether cerebral concentrations of inhaled anesthetics do not increase proportionately at inspired concentrations exceeding 3% 1) because anesthetics bind to and saturate specific sites in the brain or 2) because anesthetic-induced depression of ventilation limits the increase in alveolar anesthetic partial pressure. New Zealand White rabbits were anesthetized with methohexital, 70% nitrous oxide, and local infiltration of 1% lidocaine. Cerebral concentrations of anesthetic were determined from 19F spectra acquired with nuclear magnetic resonance (NMR). Inspired, end-tidal, and arterial anesthetic concentrations, and end-tidal and arterial partial pressure of carbon dioxide were measured. Blood/gas partition coefficients were determined and used to convert arterial anesthetic concentration to partial pressures. In seven spontaneously breathing animals, halothane (1%; n = 5) or isoflurane (0.8%; n = 2) was administered at a constant inspired concentration for 20 min; NMR spectra were acquired between 10 and 20 min. Thereafter, the inspired concentration was increased and the process repeated until apnea occurred. Two additional rabbits were anesthetized with isoflurane and studied similarly but with higher inspired concentrations during mechanical ventilation. In spontaneously breathing animals, ventilatory depression occurred, documented by marked increases in PaCO2, and cerebral concentrations of anesthetic did not increase proportionately at inspired concentrations exceeding 3%. In contrast to an absence of a correlation of inspired and cerebral concentrations during spontaneous ventilation, arterial and cerebral concentrations correlated linearly during both spontaneous and mechanical ventilation (R2 greater than 0.969). These results are consistent with depression of ventilation, rather than binding to specific cerebral sites as an explanation for the nonlinear relationship between cerebral and inspired anesthetic concentrations.

Identification of rat liver glutathione S-transferase Yb subunits by partial N-terminal sequencing after electroblotting of proteins onto a polyvinylidene difluoride membrane from an analytical isoelectric focusing gel

Rat liver glutathione S-transferases were partially purified using S-hexyl glutathione affinity chromatography, followed by native isoelectric focusing employing a pH 7-11 or pH 3-10 gradient. Proteins were excised and eluted from the gel for determination of subunit composition using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In separate experiments, isoelectric focusing gels were equilibrated with a sodium dodecyl sulfate-containing buffer at high pH, and proteins on the gel were electroblotted onto a polyvinylidene difluoride membrane, utilizing graphite plates as electrodes. The membrane-bound proteins were visualized by Coomassie Brilliant Blue staining. The protein bands were then excised from the membrane and inserted into a gas phase sequenator for direct sequencing. N-Terminal sequences thus determined were compared with published cDNA sequences. The isoelectric points (pIs) and positions on the isoelectric focusing gel of Yb1Yb1, Yb1Yb2 and Yb2Yb2 subunits were determined. We have also located on the pH 3-10 focusing gel an N-terminal blocked glutathione S-transferase which has a molecular weight similar to Yb subunits.

Stability of brain intracellular lactate and 31P-metabolite levels at reduced intracellular pH during prolonged hypercapnia in rats

The tolerance of low intracellular pH (pHi) was examined in vivo in rats by imposing severe, prolonged respiratory acidosis. Rats were intubated and ventilated for 10 min with 20% CO2, for 75 min with 50% CO2, and for 10 min with 20% CO2. The maximum PaCO2 was 320 mm Hg. Cerebral intracellular lactate, pHi, and high-energy phosphate metabolites were monitored in vivo with 31P and 1H nuclear magnetic resonance (NMR) spectroscopy, using a 4.7-T horizontal instrument. Within 6 min after the administration of 50% CO2, pHi fell by 0.57 +/- 0.03 unit, phosphocreatine decreased by approximately 20%, and Pi increased by approximately 100%. These values were stable throughout the remainder of the hypercapnic period. Cerebral intracellular lactate, visible with 1H NMR spectroscopy in the hyperoxic state, decreased during hypercapnia, suggesting either a favorable change in oxygen availability (decreased lactate production) or an increase in lactate clearance or both. All hypercapnic animals awakened and behaved normally after CO2 was discontinued. Histological examination of cortical and hippocampal areas, prepared using a hematoxylin and eosin stain, showed no areas of necrosis and no glial infiltrates. However, isolated, scattered, dark-staining, shrunken neurons were detected both in control animals (no exposure to hypercapnia) and in animals that had been hypercapnic. This subtle histological change could represent an artifact resulting from imperfect perfusion-fixation, or it could represent subtle neurologic injury during the hypercapnia protocol. In summary, extreme hypercapnia and low pHi (approximately 6.5) are well tolerated in rats for periods up to 75 min if adequate oxygenation is maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of glutathione S-transferases from day-old chick livers

Glutathione S-transferases (GSTs, EC 2.5.1.18) were isolated from the liver cytosolic fraction of 1 day old Leghorn chicks by S-hexylglutathione and glutathione affinity columns arranged in tandem. After sample loading, the affinity columns were detached from each other and developed separately. Four groups of GSTs (CL 1, 2, 3, and 4) were eluted from the hexylglutathione column, and an additional group of GSTs (CL 2 and 5) was eluted from the glutathione affinity column. CL 2, CL 3, and CL 5 were further purified to homogeneity by chromatofocusing, and the substrate specificities of each group were determined. Fractions from the chromatofocusing column were analyzed by native IEF electrophoresis. Protein bands were electroblotted onto PVDF membrane for N-terminal sequence analysis or extracted from IEF gel and rerun on SDS-PAGE to determine the subunit composition of each GST dimer. CL 2, CL 3, and CL 5 can form homodimers, whereas CL 1 and CL 4 exist only as CL 1-2 and CL 3-4 heterodimers. CL 2 and CL 5 have N-terminal amino acid sequences homologous to rat liver Yb and Ya GSTs, respectively. CL 1 has a unique N-terminal sequence that is not homologous to any known GSTs.

Cerebral metabolite dynamics during temporary complete ischemia in rats monitored by time-shared 1H and 31P NMR spectroscopy

The changes in cerebral phosphorus metabolites, intracellular pH, and lactate during 30 min of complete global ischemia and 2 h of reperfusion were monitored by time-shared 1H and 31P in vivo NMR spectroscopy in rats. After the induction of ischemia, intracellular pH decreased from 7.14 +/- 0.01 to 6.32 +/- 0.10, and lactate concentration increased from 1.6 +/- 0.4 to 15.8 +/- 2.5 mumol/g; ATP and phosphocreatine were totally depleted, while inorganic phosphate increased 715 +/- 47%. Within 1 h after blood flow was restored, high-energy phosphates and lactate levels had recovered close to baseline levels. The changes in intracellular pH and lactate levels during ischemia and reperfusion correlated well.