[Observational study on peripapillary hyper-reflective ovoid mass-like structures in children and adolescents with myopia]

Objective: To investigate the correlation of peripapillary hyper-reflective ovoid mass-like structures (PHOMS) in children and adolescents with myopia and its correlation factors. Methods: It was a cross-sectional study. From September 2021 to January 2022, myopic children and adolescents aged 6-16 years treated in Wuhan Central Hospital and Renmin Hospital of Wuhan University with a myopic spherical equivalent (SE) ≥0.5 D were consecutively included. All patients underwent best corrected visual acuity, refraction, intraocular pressure, slit lamp microscope, axial length, fundus photography and enhanced depth imaging optical coherence tomography (EDI-OCT) examination. EDI-OCT optic disc parameter measurements included diameter, degree of tilt and shift and PHOMS height. The patients were divided into PHOMS group and non-PHOMS group according to the presence or absence of PHOMS. According to the height of PHOMS, the patients were further divided into 3 subgroups: large (>400 μm), medium (200-400 μm) and small (<200 μm). The optic disc characteristics of the PHOMS group and the non-PHOMS group and each subgroup were observed, and the correlation factors of PHOMS were analyzed. Mann-Whitney U test, Kruskal-Wallis test, chi-square test, Logistic regression analysis and Kendall's tau-b correlation coefficient were used. Results: A total of 108 patients (108 eyes) were included, including 46 males (46 eyes) and 62 females (62 eyes). There were 70 eyes (64.8%) in the PHOMS group and 38 eyes (35.2%) in the non-PHOMS group. Small PHOMS can only be detected by EDI-OCT, while medium to large PHOMS showed blurred optic disc boundaries on fundoscopy images. Univariate Logistic regression analysis showed that PHOMS was associated with age (OR=1.36, 95%CI: 1.13-1.65, P=0.001) and myopic SE (OR=4.57, 95%CI: 2.51-8.32, P<0.001), axial length (OR=2.28, 95%CI: 1.37-3.82, P=0.002), optic disc tilt (OR=3.44, 95%CI: 2.09-5.66, P<0.001), optic disc shift (OR=0.95, 95%CI: 0.93-0.98, P<0.001) and optic disc diameter (OR=0.75, 95%CI: 0.58-0.95, P=0.019). Multivariate Logistic regression analysis showed that the higher the myopic SE (OR=3.01, 95%CI: 1.27-7.17, P=0.013) and the greater the tilt of the optic disc (OR=4.06,95%CI:1.99-8.29,P<0.001), the higher the risk of PHOMS. Kendall's tau-b correlation coefficient analysis showed that the height of PHOMS was negatively correlated with optic disc shift (r=-0.31, P<0.001). Conclusions: PHOMS can be found in a subset of myopic children. The fundus manifestations of PHOMS of different heights are slightly different. The large myopic SE and great optic disc tilt are risk factors of PHOMS, and their magnitudes correlate with the border tissue angle.

[HIV/AIDS surveillance in men who have sex with men aged 15-24 based on internet in Fuzhou,2016-2021]

Objective: To analyze HIV/AIDS surveillance data in men who have sex with men (MSM) aged from 15 to 24 years in Fuzhou and understand the HIV infection status in MSM and related factors. Methods: From 2016 to 2021, MSM aged 15-24 years who had oral or anal sex with men in the past 6 months were recruited through internet, and their demographic and behavioral characteristics, HIV antibody positive rate and risk factors were analyzed. Results: From 2016 to 2021, a total of 4 234 MSM aged 15-24 years were surveyed. The proportion of MSM from other provinces increased from 13.00% (85/654) to 23.42% (163/696) (trend χ²=60.23, P<0.001); and the proportion of MSM seeking male partners through internet increased from 93.27% (610/654) to 99.71% (694/696) (trend χ²=65.20, P<0.001); In the last anal sex in the past 6 months, the proportion of MSM using condom decreased from 88.16% (484/549) to 74.11% (415/560) (trend χ²=32.32, P<0.001); and in the past 6 months, the proportion of MSM using condom at each anal sex decreased from 65.76% (361/549) to 55.54% (311/560) (trend χ² =6.82, P<0.001); The proportion of MSM with HIV antibody testing increased from 5.66% (37/654) to 25.29% (176/696) (trend χ²=98.51, P<0.001). The cumulative HIV antibody positive rate in the MSM was 3.64% (154/4 234), and there was no significant difference in annual HIV antibody positive rate in the MSM (trend χ²=0.50, P=0.453). The HIV antibody positive rate in the MSM with education level of junior high school or below and the MSM living in Fuzhou for 1-2 years showed an upward trend (P<0.05). The results of multivariate logistic regression analysis showed that the risk for HIV infection in the MSM with education level of high school or technical secondary school was 0.54 times higher than that in those with education level of junior high school or below (95%CI: 0.30-0.99), and the risk for HIV infection in the MSM with education level of junior college or below was 0.29 times higher than that in those with education level of junior high school or below (95%CI: 0.17-0.51). The risk for HIV infection in the MSM who lived in Fuzhou for 1-2 years was 0.35 times higher than that in those who lived in Fuzhou for less than 1 year (95%CI: 0.16-0.74), the risk for HIV infection in the MSM who lived in Fuzhou for more than two years was 0.58 times higher than that in those who lived in Fuzhou for less than 1 year (95%CI: 0.37-0.91). The number of MSM using condoms at each anal sex was 0.18 times higher than that in the those never using condoms (95%CI: 0.08-0.42), and the number of the MSM who didn't suffered from sexually transmitted diseases was 0.25 times higher than that in those who suffered from sexually transmitted diseases (95%CI: 0.13-0.50). Conclusions: The MSM aged 15-24 years in Fuzhou have higher risk for HIV infection, and internet based intervention should be strengthened in adolescent MSM without permanent residence and with low education level.

Effect of Na2O and ZnO on the microstructure and properties of laser cladding derived CaO-SiO2 ceramic coatings on titanium alloys

To improve the bioactivity of titanium alloy (Ti-6Al-4V), CaO-SiO₂ coatings on titanium alloys were fabricated using laser cladding method. The effect of Na₂O and ZnO on the microstructure and properties of the prepared coatings was discussed. The microstructure of the CaO-SiO₂ coatings consists of cellular grains and cellular dendrites. The mutual diffusion of elements occurs between the coating and substrate. The base CaO-SiO₂ coating is composed of different phases including CaTiO₃, α-Ca₂(SiO₄), SiO₂, TiO₂ and CaO. The formation of CaTiO₃ in the ceramic layer was analyzed through thermodynamics. Na₂O has little influence on the microstructure, average hardness and wear resistance. When ZnO is added to the precursor, the microstructure turns to cell dendrite, and ZnO and Zn₂SiO₄ appear in the corresponding coating. The addition of ZnO reduces the average hardness and wear resistance of the ceramic layer. The in vitro soaking in SBF shows that the laser cladding coating has the ability to form an apatite layer.

[Study on diagnostic value of extracellular volume imaging by magnetic resonance imaging for liver fibrosis of hepatitis B]

Objective: To investigate the diagnostic value of extracellular volume (ECV) imaging by magnetic resonance imaging for liver fibrosis of hepatitis B. Methods: A retrospective analysis was recruited in patients with chronic hepatitis B, who underwent liver surgery from April to October 2017 for pathological evaluation of liver tissues, and all patients underwent Gd-EOB-DTPA-enhanced T1 mapping to calculate the liver ECV score. The correlation between ECV and staging of hepatic fibrosis and inflammatory activity were compared to clarify the diagnostic value of staging of fibrosis. Results: 66 patients were enrolled in this study. Concerning the staging of liver fibrosis, there were 13, 4, 13, 10, and 26 cases with F0, F1, F2, F3 and F4 stages, respectively. ECV values had high interobserver consistency (correlation coefficient 0.860). The ECV difference between different stages of liver fibrosis was statistically significant (F = 15.02, P < 0.001). There was a significant positive correlation between ECV and fibrosis stage (r = 0.622, P < 0.001), and weak correlation with inflammatory activity (r = 0.332, P = 0.007). Fibrosis staging was an independent factor influencing ECV (P < 0.001). The area under the receiver operator characteristic curve for the diagnosis of liver fibrosis staging F≥1, F≥3 and F4 were 0.760, 0.846 and 0.873, respectively. The diagnostic sensitivity and specificity were 64.15%, 92.31%, 77.78%, 80.00% and 88.46, 72.50%, respectively. Conclusion: MRI-ECV imaging has great value for staging hepatic fibrosis of hepatitis B, and it can provide an effective method for diagnosis, staging, and evaluating the curative effect of fibrosis.

Spinal Cord Syphilitic Gumma Presenting with Brown-Séquard Syndrome: A Case Report and Literature Review

BACKGROUND

Spinal neurosyphilis manifesting as a solitary syphilitic gumma is exceedingly rare. There are non-specific imaging findings and challenges in the diagnosis of spinal syphilitic gumma, which could be easily misdiagnosed as tumor lesions and require surgical resection or biopsy.

CLINICAL PRESENTATION

We report the case of a 45-year-old female patient who was diagnosed with Spinal syphilitic gumma. Our case is the first reported case of spinal cord syphilitic gumma with intradural-extramedullary and intramedullary involvement.

CONCLUSION

Spinal syphilitic gumma exhibits diverse clinical manifestations, lacks specific imaging features, accompanied by the patient's history deliberately concealed. Since clinicians do not have sufficient knowledge about such rare cases, misdiagnosis and missed diagnosis will be likely. When there is clinical suspicion for spinal syphilitic gumma, clinicians should pay close attention to relevant medical history, carry out a comprehensive physical examination and specific serological tests and cerebrospinal fluid (CSF) analysis. In summary, in cases with stable neurologic conditions, a trial administration of intravenous penicillin with follow-up imaging may be the optimal treatment option, and in cases with rapid progression or acute exacerbation, a surgical resection together with systemic antibiotic treatment for syphilis after surgery may be the best treatment strategy.

Effect of cardiopulmonary bypass on leukocyte activation: changes in membrane-bound elastase on neutrophils

Background: Neutrophil elastase is known to be released from the activated leukocytes as a result of cardiopulmonary bypass (CPB). However, its biological effect on organ injury is questionable because it is quickly bound by natural proteinase inhibitors (PIs). Recently, membrane-bound elastase (MBE) was found to be able to resist the PIs’ process and, thus, is biologically more active. This paper studies the effect of CPB on the kinetic change of MBE and its possible link to postoperative inflammation and organ function.

Method: Ten consecutive patients undergoing elective coronary artery bypass grafting (CABG) surgery with CPB were recruited into the study. Blood samples were taken before sternotomy, after aortic declamping, at the end of CPB, three and six hours after CPB and on the first postoperative day. MBE was determined by substrate assay from isolated neutrophils. Inflammation and organ function markers were determined according to routine laboratory methods.

Results: MBE slightly increased after aortic declamping, while it significantly increased and reached its peak at the end of CPB; it returned to its preoperative level on the first postoperative day. In contrast to lung sequestration of neutrophils, there was no transpulmonary gradient of MBE between left and right atria after aortic declamping. Neither MBE nor total MBE activity was positively correlated with postoperative inflammation markers such as blood lactate and C-reactive protein and organ function markers such as creatine phosphokinase and alanine aminotransferase.

Conclusions: CPB induces increased MBE expression on neutrophils with its peak at the end of CPB. Lack of association between neutrophil MBE and clinical markers suggests that multiple systems might be involved in the post-CPB inflammatory reaction and organ dysfunction.

AMFR gene silencing inhibits the differentiation of porcine preadipocytes

Our study clarifies the role of the autocrine motility factor receptor (AMFR) gene in porcine preadipocyte differentiation. AMFR-siRNA was transfected into porcine preadipocytes and the preadipocytes were induced to differentiation. Subsequently, qRT-PCR was conducted to examine changes in mRNA expression of a series of genes in porcine preadipocytes, including AMFR, sterol-regulatory element-binding protein-1a (SREBP1a), SREBP2, insulin-induced gene 1 (Insig1), and Insig2. Expression changes in the mRNA of genes regulating adipocyte differentiation were also analyzed using qRT-PCR, including peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and Kruppel-like factor 2 (KLF2). Western blot analysis was conducted to examine the changes in AMFR protein expression in porcine preadipocytes. Additionally, morphological changes in differentiated porcine preadipocytes were examined by oil red O staining, and changes in optical density (OD) values were measured using an ultraviolet spectrophotometer. At 24 h after transfection with AMFR-siRNA, AMFR mRNA expression significantly reduced (P < 0.01), and AMFR protein expression markedly decreased (P < 0.05). The mRNA expression of SREBP1a, SREBP2, Insig1, and C/EBPα was significantly reduced (P < 0.01), whereas the expression of KLF2 mRNA was significantly elevated (P < 0.01). After induction of preadipocyte differentiation, the number of lipid droplets decreased in the AMFR-silenced group, and the OD value markedly reduced (P < 0.05). In addition, the expression of C/EBPα mRNA significantly decreased (P < 0.05), whereas the expression of KLF2 mRNA considerably increased (P < 0.05). Taken together, silencing of the AMFR gene inhibits the differentiation of porcine preadipocytes.

Expression pattern of JMJD1C in oocytes and its impact on early embryonic development

Cell reprogramming mediated by histone methylation and demethylation is crucial for the activation of the embryonic genome in early embryonic development. In this study, we employed quantitative real-time polymerase chain reaction (qRT-PCR) to detect mRNA levels and expression patterns of all known histone demethylases in early germinal vesicle stage and in vitro-matured metaphase II (MII) oocytes (which are commonly used as donor cells for nuclear transfer). On screening, the Jumonji domain containing 1C (JMJD1C) gene had the highest level of expression and hence was used for subsequent experiments. We also found that JMJD1C was primarily expressed in the nucleus and showed relatively high levels of expression at the 2-cell, 4-cell, 8-cell, 16-cell, morula, and blastocyst stages of embryos developed from MII oocytes fertilized in vitro. Further, we knocked down the JMJD1C gene in MII oocytes using siRNA and monitored the cleavage of zygotes and development of early embryos after in vitro fertilization. The results showed that the zygote cleavage and blastocyst rates of the transfection group were reduced by 57.1 ± 0.07 and 50 ± 0.01% respectively, which were significantly lower than those of the negative control group (P < 0.05). These data suggest that JMJD1C plays a key role in the normal development of early bovine embryos. Our results also provide a theoretical basis for the investigation of the role and molecular mechanism of histone demethylation in the early development of bovine embryos.

Effects of choice of month of treatment and parity order on bovine superovulation traits

In this study, the performance of 300 Changbaishan Black cattle treated for superovulation from June to September was evaluated to determine the optimal conditions and herds for bovine embryo production. Data analysis revealed that cattle treated in July and August had higher numbers of available embryos (NAE), M1 embryos (NM1), and total embryos (NTE), as well as a higher percentage of M1 embryos (PM1). The temperature and precipitation observed during July and August were greater than those seen in the other two months; strong correlations were observed between these traits and the choice of month of treatment. In addition, multiparous cattle showed a better performance, higher NTE, NAE, NM1, and PM1 values, higher percentages of available embryos, and a lower percentage of degenerated embryos. The co-efficient correlation analysis showed that the month chosen for the treatment did not affect the superovulation traits of nulliparous cattle; however, the choice of the month affected multiparous cattle. Multiparous and nulliparous cattle exhibited many significant differences when treated in July and in August. In addition, the superovulatory traits of multiparous cattle, and not the nulliparous cattle, were strongly correlated to the choice of month of treatment. The results suggested that superovulation is more effective during a period with appropriate environmental temperature and humidity, and that multiparous cattle are more suitable for morula production.

Association of a hypoxia-inducible factor-3α gene polymorphism with superovulation traits in Changbaishan black cattle

This study was designed to examine a single nucleotide polymorphism (SNP) in the HIF-3α gene in three hundred Changbaishan black cattle using PCR-restriction fragment length polymorphism to determine whether there is an association between this SNP and superovulation. The cloning and sequencing results indicate that the polymorphism is due to a point mutation at the 278-bp position in the HIF-3α gene, resulting in 3 genotypes (AA, AB, and BB). Association analysis indicated that the polymorphism has a significant effect on the number of unfertilized embryos (NUE) (P < 0.05) in the cattle. Cattle with genotype BB had a higher NUE than those with genotype AA, but the difference in NUE between AB and AA or BB was not significant. The polymorphism also has a highly significant effect on the number of degenerative embryos (NDE) and the number of total embryos (NTE) (P < 0.01). Genotype BB was associated with a higher NDE than AA, but the difference in NDE between AB and AA or BB was not significant. Genotype BB showed a higher NTE than AA or AB, but the difference in NTE between AA and AB was not significant. No significant conclusions could be drawn with respect to susceptibility to other traits. HIF-3α could serve as a useful biomarker for donor selection, superovulation improvement, and assisted fertility.

Influence of fluoride additions on biological and mechanical properties of Na2O-CaO-SiO2-P2O5 glass-ceramics

Two series of Na2O-CaO-SiO2-P2O5 glass-ceramics doped with NH4HF2 (G-NH4HF2) or CaF2 (G-CaF2) have been prepared by sol-gel method. The glass-ceramic phase composition and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The mechanical properties and thermal expansion coefficient were measured by a microhardness tester, an electronic tensile machine and a thermal expansion coefficient tester. The structure difference between these two glass-ceramics was investigated by Fourier transform infrared spectroscopy (FTIR), and the in vitro bioactivity of the glass-ceramics was determined by in vitro simulated body fluid (SBF) immersion test. The hemolysis test, in vitro cytotoxicity test, systemic toxicity test and the implanted experiment in animals were used to evaluate the biocompatibility of the glass-ceramics. The mechanical properties of sample G-NH4HF2 are lower than that of sample G-CaF2, and the bioactivity of sample G-NH4HF2 is better than that of sample G-CaF2. The thermal expansion coefficients of these two glass-ceramics are all closer to that of Ti6Al4V. After 7 days of SBF immersion, apatites were induced on glass-ceramic surface, indicating that the glass-ceramics have bioactivity. The hemolysis test, in vitro cytotoxicity test and systemic toxicity test demonstrate that the glass-ceramics do not cause hemolysis reaction, and have no toxicity to cell and living animal. The implanted experiment in animals shows that bone tissue can form a good osseointegration with the implant after implantation for two months, indicating that the glass-ceramics are safe to serve as implants.

Insights into biological functions across species: examining the role of Rab proteins in YIP1 family function

The YIP1 family comprises an evolutionarily conserved group of membrane proteins, which share the ability to bind di-prenylated Rab proteins. The biochemical capability of YIP1 family proteins suggests a possible role in the cycle of physical localization of Rab proteins between their cognate membranes and the cytosol. YIP1 is essential for viability in yeast and a deletion of YIP1 can be rescued with the human homologue YIP1A. We have made use of this evolutionary conservation of function to generate a series of mutant alleles of YIP1 to investigate the biological role of Yip1p. Our findings indicate evidence for the participation of Yip1p in both Rab and COPII protein function; at present, we are not able to distinguish between the models that these roles represent, i.e. independent or dependent activities of Yip1p.

Quaternary ammonium functionalized poly(propylene imine) dendrimers as effective antimicrobials: structure-activity studies

Quaternary ammonium functionalized poly(propyleneimine) dendrimers were synthesized and their antibacterial properties were evaluated using a bioluminescence method. These quaternary ammonium dendrimers are very potent biocides. The antibacterial properties depend on the size of the dendrimer, the length of hydrophobic chains in the quaternary ammonium groups, and the counteranion. Since these dendrimers are well characterized and monodisperse, they also serve as an effective system to study the structure-activity relationship. The antimicrobial properties of these dendrimer biocides have a parabolic dependence on molecular weight, which is different from the bell-shaped molecular weight dependence of conventional polymer biocides. The dependence on the hydrophobic chain of the quaternary ammonium structure is similar to conventional polymer biocides, and shows a parabolic relationship with dendrimer biocides carrying C10 hydrophobes the most potent. The antimicrobial properties of these novel biocides with bromide anions are more potent than those with chloride anions. Biocides derived from hyperbranched polymers were also synthesized and found to possess somewhat lower effectiveness.

[Effects of long-term physical training on age-related changes of energy transformation of mice heart mitochondria]

AIM AND METHODS

To observe effects of long-term physical training (running wheel) on the age-related changes of energy transformation of mice heart mitochondria.

RESULTS

RCR and ADP/O decreased with age in the presence of a-ketoglutaric acid, especially in the late of age, which indicated that oxidative phosphorylation coupling decreased in the aging process.

CONCLUSION

Adaptive changes of mitochondria were brought by long-term physical training which might delay the age-related decline of mitochondrial function.

Analysis of the interactions of human ribonuclease inhibitor with angiogenin and ribonuclease A by mutagenesis: importance of inhibitor residues inside versus outside the C-terminal "hot spot"

Ribonuclease inhibitor (RI) binds diverse mammalian RNases with extraordinary avidity. Here, we have investigated the structural basis for this tight binding and broad specificity by mutational analysis of the complexes of RI with angiogenin (Ang) and RNase A (K(D)=0.5 fM and 43 fM, respectively). Both crystal structures are known; the interfaces are large, and the ligands dock similarly, although few of the specific interactions formed are analogous. Our previous mutagenesis studies focused primarily on one contact region, containing RI 434-438 and the enzymatic active site. Many single-residue replacements produced extensive losses of binding energy (2.3-5.9 kcal/mol), suggesting that this region constitutes a "hot spot" in both cases. We have now explored the roles of most of the remaining RI residues that interact with Ang and/or RNase A. One major cluster in each complex lies in a Trp-rich area of RI, containing Trp261, Trp263, Trp318, and Trp375. Although the energy losses from individual replacements in this portion of the Ang complex were small-to-moderate (0-1.5 kcal/mol), the changes from multiple substitutions were much greater than additive, and the binding energy provided by this region is estimated to be approximately 6 kcal/mol (30 % of total). Effects of replacing combinations of hot spot components had also been found to be superadditive, and this negative cooperativity is now shown to extend to the neighboring contact residue RI Ser460. The overall contribution of the hot spot, taking superadditivity into account, is then approximately 14-15 kcal/mol. The hot spot and Trp-rich regions, although spatially well separated, are themselves functionally linked. No other parts of the RI-Ang interface appear to be energetically important. Binding of RNase A is more sensitive to substitutions throughout the interface, with free energy losses>/=1 kcal/mol produced by nearly all replacements examined, so that the sum of losses greatly exceeds the binding energy of the complex. This discrepancy can be explained, in part, by positive cooperativity, as evident from the subadditive effects observed when combinations of residues in either the hot spot or Trp-rich region are replaced. These findings suggest that the binding energy may be more widely distributed in the RNase A complex than in the Ang complex.

Superadditive and subadditive effects of "hot spot" mutations within the interfaces of placental ribonuclease inhibitor with angiogenin and ribonuclease A

Previous single-site mutagenesis studies on the complexes of ribonuclease inhibitor (RI) with angiogenin (Ang) and RNase A suggested that in both cases a substantial fraction of the binding energy is concentrated within one small part of the crystallographically observed interface, involving RI residues 434-438. Such energetic "hot spots" are common in protein-protein complexes, but their physical meaning is generally unclear. Here we have investigated this question by examining the detailed interactions within the RI.ligand hot spots and the extent to which they function independently. The effects of Phe versus Ala substitutions show that the key residue Tyr434 interacts with both ligands primarily through its phenyl ring; for Tyr437, the OH group forms the important contacts with RNase A, whereas the phenyl group interacts with Ang. Kinetic characterization of complexes containing multiple substitutions reveals striking, but distinctive, cooperativity in the interactions of RI with the two ligands. The losses in binding energy for the RNase complex associated with replacements of Tyr434 and Asp435, and Tyr434 and Tyr437, are markedly less than additive (i.e., by 2.4 and 1.3 kcal/mol, respectively). In contrast, the energetic effects of the 434 and 435, and 434 and 437, substitution pairs on binding of Ang are fully additive and 2.5 kcal/mol beyond additive, respectively. Superadditivities (0.9-2.4 kcal/mol) are also observed for several multisite replacements involving these inhibitor residues and two Ang residues, Arg5 and Lys40, from this part of the interface. Consequently, the decreases in binding energy for some triple-variant complexes are as large as 8.5-10.1 kcal/mol (compared to a total DeltaG of -21.0 kcal/mol for the wild-type complex). Potential explanations for these functional couplings, many of which occur over distances of >13 A and are not mediated by direct or triangulated contacts, are proposed. These findings show that the basis for the generation of hot spots can be complex, and that these sites can assume significantly more (as with Ang) or less (as with RNase) importance than indicated from the effects of single-site mutations.

Intestinal atrophy has a greater impact on nitrogen metabolism than liver by-pass in piglets fed identical diets via gastric, central venous or portal venous routes

Whole-body nitrogen metabolism is altered during parenteral feeding as a result of gut atrophy and/or lack of splanchnic first-pass metabolism. We developed in vivo models to describe the metabolic and physiologic effects of first-pass metabolism by the small intestine/liver, liver or non-splanchnic tissues. Fifteen 2- to 4-d-old piglets were fed identical diets continuously for 8 d via gastric (IG), portal (IP) or central venous (IV) catheters. Despite similar weight gain, IV and IP pigs had higher nitrogen output and hence lower nitrogen retention (80%) compared with IG pigs (87%) (P = 0.002). Body protein content was also higher in IG pigs (583 mg/g dry matter) compared with IV (550) and IP pigs (534) (P = 0.003). Despite similar intestinal lengths, total small intestinal and mucosal weights were approximately 40% lower in IV and IP pigs than in IG pigs. Free urea cycle amino acids were altered in plasma and mucosa, suggesting that limited arginine synthesis by an atrophied gut may have limited protein deposition. Although villous atrophy was observed in the duodena and jejuna of IV and IP pigs, reduced crypt depth was observed only in IV pigs. Crypt depth was similar in all four gut sections from IG and IP pigs, suggesting that nutrient flux through the liver affects gut growth. Overall, metabolic responses to IV (non-splanchnic) and IP (liver) feeding were similar as a result of gut atrophy, whereas responses to IG (small intestine + liver) and IP (liver) feeding were different, suggesting that small intestinal atrophy affects nitrogen metabolism to a greater extent than liver by-pass.

Threonine requirement of neonatal piglets receiving total parenteral nutrition is considerably lower than that of piglets receiving an identical diet intragastrically

Evidence is accumulating that the amino acid requirements for neonates receiving total parenteral nutrition (TPN) are significantly different than those for oral feeding and need to be determined. The parenteral threonine requirement was determined in 3-d-old male Yorkshire piglets (n = 25) by examining the effect of varying dietary threonine intakes [0.05-0.6 g/(kg.d)] on phenylalanine oxidation. The diet included adequate energy, total amino acids and phenylalanine, with excess tyrosine. Phenylalanine kinetics were determined from a primed, continuous intravenous infusion of L-[1-14C]phenylalanine. Phenylalanine oxidation, estimated from the rate of 14CO2 released in expired air during isotope infusion, decreased (P < 0.05) as threonine intake increased from 0.05 to 0.15 g/(kg.d) and was low and constant for threonine intakes >0.15 g/(kg.d). Using breakpoint analysis with 95% confidence interval (CI), mean requirement and safe level of parenteral threonine intake were estimated to be 0.19 and 0.21 g/(kg. d), respectively (equivalent to 13 and 14 mg/g amino acids, respectively). To compare these data with those of orally fed controls, we then repeated the experiment by infusing identical diets intragastrically to piglets (n = 25); the varying dietary threonine intakes were 0.1-1.2 g/(kg.d). Employing identical kinetics and analyses, the mean requirement and safe level of oral threonine intake were estimated to be 0.42 and 0.51 g/(kg.d), respectively (equivalent to 28 and 34 mg/g amino acids, respectively). These data demonstrate that the threonine requirement of neonates during TPN is approximately 45% of the mean oral requirement.

Clinical trials of type I and in vitro studies of type II immunoadsorbents for systemic lupus erythematosus therapy

A highly selective immunoadsorbent was prepared by immobilization of DNA on carbonized resin beads (Type I) for the removal of the pathogenic antibodies of systemic lupus erythematosus (SLE) patients. Thirty cases of clinical trials of this SLE therapy were performed at 12 hospitals in China. The levels of anti-DNA antibodies after whole blood perfusion were decreased 40-70%. Almost all the symptoms were relieved, and some patients were freed from medicine administration. A new immunoadsorbent was prepared using aminated cellulose beads (Type II) having a higher DNA immobilization capacity of 0.6 mg/ml than the 0.4 mg/ml capacity for Type I. Stationary adsorption tests with the sera of SLE patients showed that the Type II immunoadsorbent could remove 60% of the pathogenic antibodies, which is much higher than the 30% for the Type I adsorbent.

Heat-aggregated human IgG as immunosorbent for rheumatoid arthritis

In order to selectively remove pathogenic rheumatoid factors (RF) from plasma of rheumatoid arthritis (RA) patients, a new immunosorbent was developed by immobilizing heat-aggregated human IgG (HAH IgG) on epichlorohydrin-activated agar gel. Different parameters influencing ligand coupling were studied, i.e., ligand concentration, reaction time, temperature and pH. The maximum amount of HAH IgG immobilized on the carrier was 2.7 mg/ml. Adsorption capacity was evaluated by ELISA technique. After incubation of 3.0 ml of RA plasma with 1.0 ml of the adsorbent, the RF IgM, IgG, and IgA were removed by 88%, 74%, and 50%, respectively. The decrease of total immunoglobulins and albumin were less than 7% and 9%. In vitro, perfusion of 10.0 ml plasma at 37 degrees C through 3.0 ml of adsorbent, at a flow rate of 5.0 ml/min for 60 min, resulted in the removal of 49% of RF IgM, 72% of RF IgG and 58% of RF IgA. No leakage of ligand and no decline in adsorption capacity and mechanical strength were observed after steam-sterilization.

[Studies on improving the ability of learning and memories of yangshoudan]

OBJECTIVE

To observe the effects of Yangshoudan(YSD) on the ability of learning and memories in experimental animals.

METHODS

The tests of darkness-avoidance response in normal young mice and rats, aged mice, as well as in model mice with dysmnesia induced by anisodine, model rats with dysmnesia induced by scopolamine hydrobromide and with orientation disturbance induced by pentobarbital sodium.

RESULTS

In normal young mice and rats, the error times in five minutes in learning and memories tests was reduced (P < 0.01-0.05) by YSD, while in dysmnesia groups the error times in five minutes also reduced (P < 0.01-0.05) and the incubation period of memories could be shortened by YSD. In orientation disturbance mice, the averages and percentages of correct response times increased by YSD.

CONCLUSIONS

YSD could improve the memory ability both in normal and dysmnesia which either induced by drugs or due to age. This indicates primarily that YSD has the effects of improving the ability of learning and memories and of antidementia.

Retrograde flush and cold storage for twenty-two to twenty-five hours lung preservation with and without prostaglandin E1

BACKGROUND

Our previous study showed that retrograde flush through the left atrium is better than antegrade flush in 6-hour lung preservation. Whether it is feasible in long-term lung preservation is not clear. Several studies suggested that prostaglandin E1 may not be necessary in retrograde flush because of the low vascular resistance on the venous side. This study evaluates the effects of retrograde flush and prostaglandin E1 in 24-hour lung preservation.

METHODS

Canine donor lungs were retrograde flushed with University of Wisconsin solution. Group A (n = 7) was pretreated with prostaglandin E1. No prostaglandin E1 was used in group B (n = 7). After flush and cold storage at 4 degrees C for 22 to 25 hours, left lung allotransplantation was performed. Measurements were taken before transplantation (baseline), and at 10, 30, 60, and 120 minutes after transplantation while the right pulmonary artery was occluded.

RESULTS

After 120 minutes of reperfusion, the oxygen tension and carbon dioxide tension were 643 +/- 24 and 37 +/- 3 mm Hg in group A and 600 +/- 29 and 37 +/- 3 mm Hg in group B, respectively (p = NS). Pulmonary artery pressure (group A vs group B) was 20 +/- 1 versus 28 +/- 2 mm Hg (p < 0.01); right atrium pressure: 4 +/- 1 versus 8 +/- 1 mm Hg (p < 0.01); left pulmonary vascular resistance: 1109 +/- 51 versus 1525 +/- 133 dyne.sec.cm-5 (p < 0.05); airway resistance: 22 +/- 1 versus 24 +/- 1 cm H2O/L/sec (p = NS); lung dynamic compliance: 30 +/- 1 versus 26 +/- 1 cc/cm (p < 0.05) respectively. As compared with the baseline (19 +/- 1), airway resistance was significantly increased after 2 hours of reperfusion in group B (p < 0.05). Electron microscopy revealed that type I pneumocytes, capillary endothelial cells, and epithelial cells of bronchi were well preserved and the contents of lamellar bodies of type II pneumocyte were reduced.

CONCLUSIONS

Canine lung was well preserved by retrograde flush and cold storage with University of Wisconsin solution after 24 hours preservation. Pretreatment of prostaglandin E1 is helpful in reducing pulmonary vascular resistance and airway resistance and improving lung dynamic compliance.

Site-specific mutagenesis reveals differences in the structural bases for tight binding of RNase inhibitor to angiogenin and RNase A

RNase inhibitor (RI) binds with extraordinary affinity (Ki approximately 10(-13)-10(-16) M) to diverse proteins in the pancreatic RNase superfamily. In the present study, the structural basis for the recognition of two RI ligands, human angiogenin (Ang) and bovine RNase A, has been investigated by site-specific mutagenesis of human RI and Ang. The RI residues examined were those that appear to form strong contacts with RNase A in the crystal structure of the porcine RI x RNase A complex [Kobe, B. & Deisenhofer, J. (1995) Nature (London) 374, 183-186] that would not be replicated in the Ang complex. Ala substitutions of five of these residues (Glu-287, Lys-320, Glu-401, Cys-408, and Arg-457) were found to have little or no effect on binding of RNase A. In contrast, replacements of Tyr-434, Asp-435, and Tyr-437 and deletion of the C-terminal residue Ser-460 substantially weakened affinity for RNase A: the losses of binding energy associated with the mutations were 5.9, 3.6, 2.6, and 3.5 kcal/mol, respectively. Thus these four residues, which are neighbors in the tertiary structure, appear to constitute a "hot spot" for the RNase A interaction. However, only one of them, Asp-435, was equally important for binding of Ang; the Ki increases produced by mutations of the others were 20- to 93-fold smaller for Ang than for RNase A. Consequently, Tyr-434 plays a significant but lesser role in the Ang complex, whereas Tyr-437 and Ser-460 make only minor contributions. Ala mutations of four Ang residues (His-8, Gln-12, Asn-68, and Glu-108) that correspond to RI contacts on RNase A produced no major changes in affinity for RI. These findings indicate that RI uses largely different interactions to achieve its extremely tight binding of RNase A and Ang.

Pulsed brachytherapy as a substitute for continuous low dose rate: an in vitro study with human carcinoma cells

PURPOSE

Pulsed dose rate (PDR) brachytherapy as a substitute for continuous low dose rate (CLDR) has the potential to be a useful option in brachytherapy. However, the frequency and duration of pulses that will produce results practically equivalent to CLDR is still an open and important question. This study was designed to compare the survival of human tumor cells, cultured in vitro, and exposed to continuous or pulsed irradiation where the pulse frequency was varied.

METHODS AND MATERIALS

Three different human carcinoma cells, derived from cervical and breast cancers, were exposed to CLDR gamma rays, or to pulsed irradiations with the same overall dose rate. Pulsed regimens used were 3.8 min every hour, 7.6 min every 2 h, 11.4 min every 3 h, 15.2 min every 4 h, 22.8 min every 6 h, and 45.6 min every 12 h. For each comparison between CLDR and PDR, the overall dose and the overall time were the same. Experimental design was such that significant differences in biological effectiveness, if present, would be detected.

RESULTS

For the cell lines investigated, hourly pulses resulted in cell survival indistinguishable from CLDR. However, as the pulse interval was increased, cell survival progressively decreased compared with CLDR, and the pulsed regimes were no longer equivalent to continuous low dose rate.

CONCLUSIONS

This study provides some evidence to support the suggestion that a 10-min pulse, repeated every 1 to 2 h, would be functionally equivalent to a continuous low dose rate irradiation, at least in terms of early responding endpoints. Longer intervals between pulses might result in loss of equivalence in some cases.

Retrograde versus antegrade flush in canine left lung preservation for six hours

BACKGROUND

Retrograde flush through the left atrium is now used by some investigators in clinical lung preservation. However, to date there are no studies which compare its result with that of routine antegrade flush.

METHODS

Mongrel dogs were divided into two groups: antegrade group (n = 7) and retrograde group (n = 8). After flush and 6 hours of cold storage in Euro-Collins solution, the left lung was transplanted in weight matched recipients, and their right pulmonary artery was then clamped at 10-, 30-, 60-, and 120-minute intervals for 10 minutes to test the lung function. The ultrastructure of lungs in both groups were also studied.

RESULTS

Results showed the following (antegrade group versus retrograde group): the wet/dry ratio of the transplanted lung was 7.14 +/- 0.15 versus 6.33 +/- 0.20 (p < 0.01); the arterial oxygen tension (mm Hg) was 389 +/- 42 versus 534 +/- 23 (p < 0.05) and 370 +/- 51 versus 580 +/- 37 (p < 0.01) at 60 and 120 minutes, respectively. The peak airway pressure (cm H2O) was 23.4 +/- 0.8 versus 20.6 +/- 0.6 (p < 0.05) and 23.7 +/- 0.6 versus 21.3 +/- 0.8 (p < 0.05) at 10 and 60 minutes, respectively. Electron microscopic studies showed that at the end of preservation, type I and type II pneumocytes and capillaries were normal in both groups. Occluded capillaries with red blood cells were found in the antegrade group. After reperfusion, damaged epithelium and thicker air-blood barrier were found in the antegrade group.

CONCLUSIONS

Retrograde flush offers a better lung preservation with less edema, decreased airway resistance, and improved oxygenation as compared with the antegrade group in 6 hours lung preservation.

Improved 4- and 6-hour myocardial preservation by hypoxic preconditioning

BACKGROUND

A brief hypoxic episode can precondition myocardium against a subsequent ischemic-reperfusion injury. The present study sought to determine whether intracellular ionic alterations, induced expression of heat-shock proteins (hsps), and/or catalase are involved in the cellular mechanisms by which hypoxic preconditioning can preserve postischemic function in a model of prolonged hypothermic storage.

METHODS AND RESULTS

Two groups of isolated working rat hearts were studied: control (CON) and hypoxically preconditioned (HP) hearts. Hearts were arrested at 4 degrees C with St Thomas' cardioplegic solution and immersion-stored for either a 4- or 6-hour period. Myocardial function (ie, heart rate, aortic flow, coronary flow, developed pressure, and its first derivative dP/dtmax) was determined at baseline, after preconditioning, and during reperfusion. At similar time points, myocardial [Na+]i, [K+]i, [Mg2+]i, and [Ca2+]i were measured using an atomic absorption spectrophotometer, and the induction of hsp 70 and catalase mRNAs was assayed using Northern blot analysis. After 4 and 6 hours of hypothermic storage, aortic flow, dP/dtmax, and [K+]i were increased, whereas [Na+]i and [Ca2+]i were decreased significantly in the HP group compared with the CON group. Steady state mRNA levels of catalase and hsp 70 were increased from baseline levels only in the HP group, with a peak (2.8- and 2.4-fold versus baseline) after 4 hours of storage.

CONCLUSIONS

Our results indicate that intracellular ionic alterations and upregulation of catalase and hsp 70 gene expression may contribute to the mechanisms underlying hypoxic preconditioning, leading to improved postischemic function during prolonged hypothermic storage of hearts.

Clinical trials of immunoadsorbent in systemic lupus erythematosus therapy

Five patients with systemic lupus erythematosus (SLE) were perfused through an extracorporeal shunt filled with DNA-immunoadsorbent (DNA immobilized on carbonized resin beads). High concentrations of anti-DNA antibodies (36.4-67.0%) (binding percentage with 125I-DNA) in the serum of SLE patients were reduced to 13.8-53.0%, respectively. The highest removal percentage was 62.1%. Although the decline levels varied, the symptoms of patients, i.e., long-term severe joint pain, severe edema, hydropericardium, and ascites were all relieved considerably. The immunoadsorbent showed satisfactory blood compatibility.

Hypoxic preconditioning enhances functional recovery after prolonged cardioplegic arrest

The purpose of this study was to assess the ability of hypoxic preconditioning to improve myocardial salvage after prolonged hypothermic cardioplegic arrest. Isolated working rat hearts were arrested at 4 degrees C with St. Thomas' Hospital cardioplegic solution and immersion stored for 4 or 6 hours. Two groups were studied, control and hypoxically preconditioned (HP) hearts. After 4 hours' preservation, aortic flow, coronary flow, and the first derivative of aortic pressure were 8.7 +/- 1.6 mL/min, 17.8 +/- 1.6 mL/min, and 2,064 +/- 123 mm Hg/s, respectively, in control hearts (n = 11) and 25.7 +/- 2.5 mL/min, 27.1 +/- 2.5 mL/min, and 2,655 +/- 93 mm Hg/s, respectively, in HP hearts (n = 11) (p < 0.05). After 6 hours' preservation, aortic flow, coronary flow, and the first derivative of aortic pressure were 3.5 +/- 1.2 mL/min, 18.8 +/- 0.4 mL/min, and 1,622 +/- 226 mm Hg/s, respectively, in control hearts (n = 6) and 21.5 +/- 3.2 mL/min, 25.5 +/- 2.3 mL/min, and 2,439 +/- 239 mm Hg/s, respectively, in HP hearts (n = 6) (p < 0.05). After 6 hours' preservation, adenine nucleotides and creatine phosphate levels were not significantly different between the two groups, but lactate dehydrogenase release was significantly increased (p < 0.05) in control versus HP hearts (4.66 +/- 0.58 IU/L versus 1.98 +/- 0.28 IU/L). We conclude that hypoxic preconditioning reduces cellular necrosis and preserves myocardial function after prolonged hypothermic cardioplegic arrest.

Radiopotentiation of human brain tumor cells by the spermine analog N1,N14-bis(ethyl)homospermine

PURPOSE

To determine whether the cytotoxicity produced by radiation can be increased by the spermine analog N1,N14-bis(ethyl)homospermine (BE-4-4-4).

METHODS AND MATERIALS

Two human tumor cell lines, SF-126 and U-251 MG, were either treated with 0.1 or 0.4 microM BE-4-4-4 for 3 or 4 days, or with 0.2 microM BE-4-4-4 for 4 days. At the end of BE-4-4-4 treatment, cells were irradiated and assayed immediately. Polyamine levels, cell survival, and cell number were determined.

RESULTS

In SF-126 cells, treatment with 0.2 microM BE-4-4-4 for 4 days killed about 50% of the cells and also increased the cytotoxicity of radiation. The dose enhancement ratio was approximately 1.3:1.5, which is similar to that reported for alpha-difluoromethylornithine. Polyamine levels were partially depleted, and growth was inhibited to about 60% of control levels. Pretreatment of cells with either 0.1 or 0.4 microM BE-4-4-4 for 3 or 4 days produced less of an increase in radiation-induced cytotoxicity, even though these exposures killed 30-40% or 60-90% of the cells, respectively. Similar treatment with 0.1-0.4 microM BE-4-4-4 in U-251 MG cells had minimal effects on cytotoxicity and growth inhibition, while treatment with 1.0 microM and 2.0 microM BE-4-4-4 for 4 days produced more than a 50% depletion in polyamine levels and partial inhibition in growth, but failed to demonstrate radiopotentiation.

CONCLUSION

The cytotoxic polyamine analog BE-4-4-4 can increase the cytotoxicity caused by radiation in at least one cell line. The amount of potentiation depends on the concentration of the analog, with the most occurring at the intermediate concentration. Because we did not observe potentiation in both cell lines, and because of the dose dependence seen in SF-126 cells, the clinical efficacy produced by combined BE-4-4-4 and radiation protocols may be limited.

HIV-related knowledge and attitudes among medical students in China

A modified version of the 'WHO/KABP Questionnaire for Students' was administered to 302 students at a medical university in China. The instrument included items to assess the students' demographic background, knowledge of AIDS/HIV, attitudes about AIDS, as well as towards people infected with HIV, those groups commonly labelled as 'high risk' and toward sources of information. The average score on the knowledge scale was 80% correct. There was a substantial disparity in knowledge between how HIV is transmitted and how HIV is not transmitted--90% of the former items were answered correctly, while only 72% of the latter were answered correctly. Over 40% of the sample blamed prostitutes for AIDS in China, whereas 22% blamed drug addicts and 6% blamed homosexuals. Two-thirds of the sample indicated that they thought people with AIDS got what they deserve. About one-third of the sample supported quarantine measures as well as keeping infected students out of classrooms. Nearly half of the sample indicated that they did not trust any of the official sources of health information we asked about and 27% said that they thought the government was concealing information about AIDS.

Clinical trials for removal of bilirubin by high-capacity nonionic adsorbent

To remove bilirubin from patients with hyperbilirubinemia, nonionic macroporous adsorbent NK-110 was tailor-made from styrene and divinyl benzene at Nankai University. Five patients were perfused through shunts filled with 500 ml of the above adsorbent. After 2 h of hemoperfusion, total bilirubin decreased within the range of 22-51%. During the treatment, no noticeable changes in electrolytes, urea nitrogen, serum glutamicpyruvic transaminase (SGPT), TTT, and amino acid concentrations were observed. Platelet depletion was satisfactory. Hemoglobin, white cell count, globulin, and albumin showed no remarkable changes. The nonionic adsorbent shows a high efficacy for bilirubin removal and has a great potential for future clinical applications.

[A study of hygienic standard for titanium in the source of drinking water]

The smell and taste thresholds of titanium in water were tested. The results indicated that the concentration of smell and taste thresholds for Titanium were 4.329mg/L and 3.332mg/L respectively. The threshold below value of autopurification was 0.1mg/L. The toxicity assessment showed that the acute toxicity of titanium by oral route was of low order according to the toxicity classification. There was no obvious cumulative effect, nor was there mutagenesis demonstrable. Chronic toxicity test of titanium in rats showed that the maximum non-effective concentration was 1.08mg/L. It is suggested that the maximum allowable concentration of titanium in drinking water may be 0.1 mg/L.

[Analysis of 7 elements in the serum and lens of senile cataract patients]

The contents of Fe, Al, Cu, Zn, Ca, Mg and P in the serum and lens of senile cataract patients were determined with inductively coupled plasma (ICP) spectrometry to find that (1) the Fe, Al, Zn and Ca levels in senile cataractous lenses were significantly higher, and the P level lower than those in normal subjects; however, the serum levels of Fe, Al, Zn and Ca were significantly lower, and the level of P higher than those in normal subjects; (2) the serum levels of Cu and Zn varied with the duration of cataract, which could explain the inconsistency among authors with regard to these parameters; (3) the relation between Fe and Al and the development of cataract remained to be elucidated; (4) the Ca/P ratio in senile cataractous lenses was 50 times (1:0.02) that in clear lenses; these 2 elements were regarded to have close relation with cataractogenesis; and (5) Cu and Mg were not related to cataractogenesis, a finding in agreement with most reports.

Retinopathy, neuropathy and nephropathy in non-insulin-dependent diabetic patients

In 1978, an epidemiological survey for adult diabetes was conducted in Taipei City. A total of 219 Chinese non-insulin-dependent diabetic patients were discovered and 217 of them were examined for retinopathy, neuropathy and nephropathy. Among the 110 men and 107 women studied, 63.1% were free of complications and the prevalences for retinopathy, nephropathy and neuropathy were 24.0%, 12.9% and 23.5%, respectively. The clinical and biochemical data of the patients were compared. For those with and those without complications, the diabetic duration (8.2 +/- 6.7 vs 4.1 +/- 2.7, years), percentage of insulin treatment (8.8% +/- 0.7%), percentage of hypertension (42.5% vs 26.3%), and the fasting plasma glucose (182.8 +/- 63.6 vs 135.0 +/- 44.6, mg/dl) were significantly different. Diabetic duration and glycemic control consistently correlated with retinopathy, nephropathy and neuropathy. Hypertension and insulin treatment were also associated positively with the complications. The more complications the diabetic patients had, the poorer the glycemic control, the longer the diabetic duration, a higher percentage of insulin treatment and hypertension were found.

Modified Wicomb's apparatus for preservation of heart for 24 hours

To prolong the time of heart preservation, we modified the Wicomb's perfusion apparatus, in which oxygen flow acts as the source of power and provides oxygenation for the perfused myocardium. Ten adult porcine hearts which had been preserved for 24 hours were resuscitated successfully and continued to beat steadily for more than 1.5-3 hours after reperfusion. Myocardial ultrastructure was observed at the end of preservation and 15-120 minutes after reperfusion. The damages of the myocardial ultrastructure at the end of preservation were reversible.

Gel electrophoresis method for quantitation of gamma ray induced single- and double-strand breaks in DNA irradiated in vitro

We describe a method based on gel electrophoresis for the quantitation of strand breaks in DNA and demonstrate its application to the measurement of single- and double-strand breaks formed by gamma-rays for DNA irradiated in vitro. For single-strand breaks, our data span the dose range from 0.1 to 1 Gy, while for double-strand breaks doses were from 3 to 15 Gy. In agreement with results obtained using other techniques, we find that the dose response function for single-strand breaks is linear while the dose response function for double-strand breaks is curved, indicating that it is the sum of both linear and quadratic components. We discuss factors that determine the sensitivity of the method and indicate approaches to make possible the quantitation of strand breaks in the DNA of cells irradiated with sublethal doses.

Removal of unconjugated bilirubin by macroreticular resin in hemoperfusion

Macroporous polystyrene and polyvinylpyridine beads with quaternary ammonium and tertiary groups were tailor-made for the adsorption of unconjugated bilirubin. In vitro studies in order to obtain high adsorption capacity, the synthesized macroporous resin should have an average pore size of about 160 A and with surface area as large as possible. As the crosslinking of the resin increased from 4%-40% the amount of bilirubin adsorbed increased from 0.17 mg/g to 2.0 mg/g. Resins containing strong basic groups have higher adsorption capacities than their corresponding weak base groups. Adsorption mechanism studies showed that both chemical and physical adsorption took place. Adsorption of bilirubin in plasma was some what lower than in buffer solution.

Biophysical mechanism of radiation damage to mammalian cells by X- and gamma-rays

Published information on the reproductive death in mammalian cells irradiated by a wide range of X- and gamma-ray energies has been re-analysed to extract intrinsic efficiencies of damage for the secondary electrons in transient equilibrium. On a log-log plot, a linear dependence on the track average l.e.t. and the average specific primary ionization is found, indicating that either serves as a good quality parameter. The soft X-ray data are consistent with this conclusion. Upon comparison with data for fast heavy ion irradiations, the average specific primary ionization is shown to be applicable independently of radiation type whereas track average l.e.t. is not. Furthermore it is revealed that electrons are most damaging near the end of their range but their efficiency is only about 10-20 per cent of that of fast ions at the same quality, possibly due to the influence of multiple scatter on the electron penetration depth. It is deduced that, for the dose rates involved, the damage by electrons is predominantly by intra-track action and not inter-track action. The results are consistent with the suggestion that optimum damage occurs when the mean free path between ionizations is equivalent to the strand separation in the double-stranded DNA.

X-ray photoelectron spectra study on the derivatives of N-beta-phenethyl amine and N-beta-phenethyl glycine

The X-ray photoelectron spectra of sixteen derivatives of N-beta-phenethyl amine and N-beta-phenethyl glycine have been studied. The effect of different structures on N1s binding energy and that of their Pauling's atomic charge density on the nitrogen atoms are investigated. The experimental binding energy of N1s is proportional to the calculated Pauling's atomic charge density. It shows that the phosphoryl group is the strongest nitrogen lone pair electron localizing group as compared with the corresponding sulfonyl and acyl derivatives. The XPS results agree with the data that there is no decarbonylation during the synthesis of N-dialkylphosphoryl-tetrahydro-3-benzazepin-1-one. In addition, since the N1s in P-N bond is smaller than that in S-N and C-N bonds, the phosphoryl group can be removed under much milder conditions. These results provide a semi-empirical evidence for the synthesis of the skeleton of the cephalotaxine. It also differentiates the reaction paths for these three different amino protecting groups.