[The treatment of rat fulminant hepatic failure by auxiliary partial heterotopic liver transplantation: experimental study]

OBJECTIVE

To confirm the effect of auxiliary partial heterotopic liver transplantation (APHLT) in the treatment of fulminant hepatic failure (FHF).

METHOD

On 30 rat models of FHF, 62% of partial liver grafts were implanted below the host residual liver with 28 successful operations. The survival rate, biochemical test for liver function, (99m)Tc-HIDA liver scintigraphy and pathological changes of the grafts and host livers were studied.

RESULT

The survival rate in 48 hours was 71.4% compared with 0% in 15 FHF animals. 14 days after the operation, the host liver regenerated obviously and the liver function recovered while the graft shrank gradually. 30 days later, the graft became fibrosis completely.

CONCLUSION

Depending on the temporary function support of the graft, the native residual liver could regenerate and restore its function while the graft tended to atrophy.

Constitutive IL-10 production accounts for the high NK sensitivity, low MHC class I expression, and poor transporter associated with antigen processing (TAP)-1/2 function in the prototype NK target YAC-1

Tumor cells that are treated with rIL-10 or transfected with the IL-10 gene show phenotypic changes. These include low but peptide-inducible expression of MHC class I, low sensitivity to specific CTL-mediated lysis, and increased NK sensitivity. In vitro-established mouse tumor lines were screened for IL-10 expression and production, and a large proportion of plasmocytomas or T cell lymphomas were found to produce IL-10. Since one of these lines was the prototype NK target cell YAC-1, we investigated whether the high IL-10 production of this cell line was related to its high NK sensitivity and its defects in MHC class I expression. The decrease in H-2 expression following the in vitro culture of in vivo-passaged YAC-1 cells was accompanied by a gradual increase in IL-10 production, whereas the reverse was found when passing in vitro-grown YAC-1 in vivo as an ascites tumor in syngenic mice. In addition, differences in YAC-1 MHC class I expression correlated with alterations in the functional activity of TAP-1/2 proteins. YAC-1 cells that were transduced with a retroviral IL-10 antisense construct (Y-IL-10 AS) only produced about half of the IL-10 that was produced by YAC-1 transduced with the control construct (Y-IL-10 Mock). Relative to Y-IL-10 Mock cells, the expression of H-2 on Y-IL-10 AS cells was markedly increased, and NK sensitivity was decreased. These data argue for a mechanism wherein IL-10 production is causally related to the low H-2 expression, decreased TAP function, and high NK sensitivity of YAC-1 cells.

Cellular localization of tumor necrosis factor alpha following focal cerebral ischemia in mice

Tumor necrosis factor alpha (TNFalpha) is a pleiotrophic cytokine with diverse proinflammatory actions. Focal cerebral ischemia induces rapid and dramatic increases in TNFalpha levels within and surrounding the focus of damaged brain both in striatum and cortex. The actions of TNFalpha during cerebral ischemia may be related to the cell types which deliver and/or accept TNFalpha signals. However, the cellular sources of TNFalpha following cerebral ischemia have not been fully elucidated. The present study was designed to determine the cellular localization of TNFalpha following permanent middle cerebral artery occlusion (MCAO) in mice. As judged by immunohistochemistry, TNFalpha expression in the ischemic hemisphere was increased at 3 h following MCAO, peaked at 6 to 12 h, and decreased at 24 h. Double immunostaining for TNFalpha and neuron specific enolase (NSE) or glial fibrillary acidic protein (GFAP) showed that TNFalpha positive neurons were observed in both the ischemic core and perifocal region, while TNFalpha positive astrocytes were observed in the outer cortical layer, the corpus callosum, the molecular layer of the hippocampus, and periventricular areas. The presence of TNFalpha immunoreactivity in neurons and nerve fibers following MCAO suggests that TNFalpha expressed in ischemic neurons might be delivered via axonal transport, while TNFalpha immunoreactivity in astrocyte end-feet and ependymal cells following MCAO suggests that TNFalpha may be involved in blood-brain barrier disruption and the initiation of inflammation in the brain.

[A study of the expression of c-myc onoprotein in laryngeal cancer and different distant adjacent mucosa]

Using citric-LSAB-microwave immunohistochemical technique, the expression of c-myc was studied in different regions of larynx including laryngeal squamous cell carcinoma (LSCC), border area, adjacent mucosa which was 0.5, 1.0, 1.5 and 2.0 cm away from cancer 30 cases and four cases of normal laryngeal mucosa. The results showed that over-expression of c-myc in LSCC was found in 29 of 30 (96.7%), which was higher than that in normal laryngeal mucosa (P < 0.01). A significant different expression of c-myc can be seen at the regions of 2.0 and 1.5 cm distant from the tumor (P < 0.05). The expression of c-myc increased as tissue progressed in sequence from normal mucosa, adjacent mucosa to carcinoma. The c-myc expression did not correlate with site of tumor, stage and histological grade (P > 0.05). The results indicate that over-expression of c-myc is involved in genesis of LSCC, and may be an early event in the development of human squamous-cell carcinoma of the larynx. The tissue adjacent to the tumor may have a potential malignancy.

Inhibition of TNFalpha attenuates infarct volume and ICAM-1 expression in ischemic mouse brain

The purpose of our study was to determine whether inhibiting the action of tumor necrosis factor-alpha (TNFalpha) attenuates brain injury and reduces inflammatory responses in the mouse during ischemia and reperfusion. Mice underwent middle cerebral artery occlusion (MCAO) for 1 h followed by 23 h reperfusion. Monoclonal neutralizing anti-murine TNFalpha antibody (mAb) was administrated intraventricularly in the mouse with temporary MCAO. Infarct volume in the anti-TNFalpha mAb treated mice was significantly smaller than that in the control group (p < 0.05). The number of intercellular adhesion molecule-1 (ICAM-1)-positive vessels in the ischemic area of the anti-TNFalpha mAb-treated group was significantly less than that in the control group. Our study demonstrated that blocking TNFalpha reduced brain injury and attenuated ICAM-1 expression during transient cerebral ischemia.

Advances in biopharmaceutical analysis in the People's Republic of China 1995-1997

The present paper is the third biannual review in succession to the author's previous publications (Z.L. Qin, Advances in biopharmaceutical analysis in the People's Republic of China: 1991-1993, J. Pharm. Biomed Anal. 13, 1995, 1-7 and Z.L. Qin, Advances in biopharmaceutical analysis in the People's Republic of China: 1993-1995, J. Pharm. Biomed. Anal. 14, 1996, 1395-1403), regarding the methodological study and progress in biopharmaceutical analysis by RP-HPLC, GC and GC-MS selected from relative journals between April 1995 and March 1997 in P.R. China. The published methods were widely adopted in pharmacokinetic and metabolic studies. Investigation on drug metabolism were conducted more deeply, both in vitro and in vivo, for searching the structure of metabolites and drug metabolic pathways. The use of high performance CZE as a new trend for the analysis of drugs and metabolites in biofluids was also reported.

Replication at the telomeres of the Streptomyces linear plasmid pSLA2

The Streptomyces linear plasmid pSLA2 initiates DNA replication bidirectionally towards its telomeres from a site located near the centre of the molecule; at the telomeres, the recessed ends of lagging strands are filled in by non-displacing DNA synthesis. Here, we report experiments that test three proposed mechanisms for lagging-strand fill-in. We present data inconsistent with recombinational or terminal hairpin models for the formation of full-length duplex pSLA2 DNA. Instead, we find that deletions in short, distantly separated homologous palindromes in the leading-strand 3' overhang prevent propagation of linear pSLA2 DNA, implicating a mechanism of palindrome-mediated leading-strand fold-back in telomere replication. We further show that circularized pSLA2 DNA molecules are opened in vivo precisely at the terminal nucleotides of telomeres, generating functional linear replicons containing native telomeres covalently bound to a protein at their 5' DNA termini. Together, our results support a model in which pairing of multiple widely separated pSLA2 palindromes anchors the 3' end of the leading-strand overhang to a site near the overhang's base -- providing a recognition site for terminal-protein-primed DNA synthesis and subsequent endonucleolytic processing. Thus, the replication of Streptomyces plasmid telomeres may have features in common with the mechanism proposed for telomere replication in autonomous parvoviruses.

B cells inhibit induction of T cell-dependent tumor immunity

Cytotoxic T lymphocyte (CTL) mediated tumor immunity against major histocompatibility antigen (MHC) class I-positive but class II-negative tumors often requires help from CD4+ T cells. These CD4 cells are activated by MHC class II-positive cells that present tumor derived antigens. Considering that different antigen presenting cells, such as B cells, macrophages and dendritic cells compete for antigen and influence the outcome of an immune response, we analyzed tumor immunity in B cell-deficient mice. These mice appear normal with regard to T cell immunity and tolerance to some pure foreign antigens. We show here that the low immunogenicity of tumors is caused by B cells whose presence in the priming phase results in disabled CD4+ T cell help for CTL mediated tumor immunity. Instead, in the presence of B cells, a non-protective humoral immune response is induced. Our results may explain the enigmatic observation that tumor-reactive antibodies occur frequently in cancer patients.

The Gfi-1B proto-oncoprotein represses p21WAF1 and inhibits myeloid cell differentiation

Gfi-1 is a cellular proto-oncogene that was identified as a target of provirus integration in T-cell lymphoma lines selected for interleukin-2 (IL-2) independence in culture and in primary retrovirus-induced lymphomas. Gfi-1 encodes a zinc finger protein that functions as a transcriptional repressor. Here we show that Gfi-1B, a Gfi-1 related gene expressed in bone marrow and spleen, also encodes a transcriptional repressor. IL-6-induced G1 arrest and differentiation of the myelomonocytic cell line M1 were linked to the downregulation of Gfi-1B and the parallel induction of the cyclin-dependent kinase inhibitor p21WAF1. Experiments addressing the potential mechanism of the apparent coordinate regulation of these genes revealed that Gfi-1B represses p21WAF1 directly by binding to a high-affinity site at -1518 to -1530 in the p21WAF1 promoter. Forced expression of Gfi-1B, but not of Gfi-1B deletion mutants lacking the repressor domain, blocked the IL-6-mediated induction of p21WAF1 and inhibited G1 arrest and differentiation. We conclude that Gfi-1B is a direct repressor of the p21WAF1 promoter, the first such repressor identified to date, and that sustained expression of Gfi-1B blocks IL-6-induced G1 arrest and differentiation of M1 cells perhaps because it prevents p21WAF1 induction by IL-6.

Effects of a sudden flow reduction on red blood cell rouleau formation and orientation using RF backscattered power

In most studies that were aimed at evaluating the kinetics of red blood cell (RBC) aggregation, human blood was initially circulated at a high shear rate to disrupt the aggregates, and measurements were performed following a complete flow stoppage, during the process of rouleau formation. However, it is known that a very low shear rate can enhance the formation of aggregates, as demonstrated by the modal relationship of the shear-rate dependence of RBC aggregation. The objective of the present study was, thus, to evaluate the influence of sudden flow reductions compared to a complete flow stoppage on the kinetics of rouleau formation, using ultrasound backscattering. Horse blood models, characterized by different aggregation levels, were obtained by diluting the plasma with a saline solution in different proportions. Blood was circulated in a 12.7-mm vertical tube at a flow rate of 1250 mL min-1 (prereduction flow rate) to disrupt the aggregates. The ultrasound radiofrequency (RF) signal was recorded from the center of the tube following different levels of sudden flow reduction or complete stoppage (postreduction flow rate). All measurements were performed over 2 min, using a 10-MHz transducer. No power increase was observed after complete flow stoppage. For postreduction flow rates varying between 20 and 160 mL min-1, the backscattered power increased proportionally with the kinetics of RBC aggregation. The echo buildup was also faster and stronger when the postreduction flow rate was increased. An unexpected pattern of variation of the backscattered power was found for horse RBCs characterized by high kinetics of rouleau formation. The power increased rapidly to a plateau, followed by another rapid increase and another plateau. Rouleau formation, random disorientation and reorientation were postulated to explain the phasic power increases observed.

Double suicide gene (cytosine deaminase and herpes simplex virus thymidine kinase) but not single gene transfer allows reliable elimination of tumor cells in vivo

Suicide genes such as cytosine deaminase (CD) and herpes simplex virus thymidine kinase (TK) encode products that convert nontoxic substances (prodrugs) into toxic metabolites. Suicide gene transfer is currently being used in cancer therapy or can be used as a safety modality. To analyze the reliability of suicide genes as a safety modality for a vaccination study with viable cytokine/B7 gene-modified tumor cells, the individual and combined efficacy of the two suicide genes was compared for in vitro and in vivo cell killing of a murine mammary adenocarcinoma cell line (TS/A). To adapt the system to an in vivo gene delivery situation, bulk cultures cotransfected with the CD and TK gene were used instead of selected clones. In vitro, both CD and TK conferred sensitivity to the respective prodrug but the combined cytotoxic effects of both gene products were always superior. For in vivo analysis BALB/c mice were injected subcutaneously with CD- and TK-modified TS/A cells, treated with prodrugs, and tumor size was evaluated for a period of 100 days. In the in vivo situation the combination of both enzyme/prodrug systems was again most effective. The highest single concentration of 5-FC (500 mg/kg) or GCV (100 mg/kg) was not able to fully protect the animals from developing tumors, whereas a combination of 5-FC (250 mg/kg) and GCV (50 mg/kg) resulted in complete tumor eradication. In nude mice treated in the same way, most CD/TK tumors could not be eliminated. Furthermore, BALB/c mice cured of TS/A-CD/TK tumors developed a systemic tumor immunity against challenge with parental TS/A cells. These findings indicate that reliable tumor elimination by the suicide genes depends on T cells. The cooperative effect of both suicide genes was confirmed in vitro with the human renal cell carcinoma line RCC26. We conclude that TK and CD together, but neither gene alone, act as a safety mechanism for the elimination of tumor cells in a reliable fashion and suggest that a rapid and quantitative antigen release by effective TK- and CD-mediated tumor destruction is necessary for T cell immunity to develop.

[Chemical constituents of the stem and root of Syzygium buxifolium Hook. Et Arn]

Six crystalline substances were isolated from the stem and root of Syzygium buxifolium and identified as friedelin, beta-sitosterol, ursolic acid, pomolic acid, oleanolic acid and beta-daucosterol.

Loss of conformational stability in calmodulin upon methionine oxidation

We have used electrospray ionization mass spectrometry (ESI-MS), circular dichroism (CD), and fluorescence spectroscopy to investigate the secondary and tertiary structural consequences that result from oxidative modification of methionine residues in wheat germ calmodulin (CaM), and prevent activation of the plasma membrane Ca-ATPase. Using ESI-MS, we have measured rates of modification and molecular mass distributions of oxidatively modified CaM species (CaMox) resulting from exposure to H2O2. From these rates, we find that oxidative modification of methionine to the corresponding methionine sulfoxide does not predispose CaM to further oxidative modification. These results indicate that methionine oxidation results in no large-scale alterations in the tertiary structure of CaMox, because the rates of oxidative modification of individual methionines are directly related to their solvent exposure. Likewise, CD measurements indicate that methionine oxidation results in little change in the apparent alpha-helical content at 28 degrees C, and only a small (0.3 +/- 0.1 kcal mol(-1)) decrease in thermal stability, suggesting the disruption of a limited number of specific noncovalent interactions. Fluorescence lifetime, anisotropy, and quenching measurements of N-(1-pyrenyl)-maleimide (PMal) covalently bound to Cys26 indicate local structural changes around PMal in the amino-terminal domain in response to oxidative modification of methionine residues in the carboxyl-terminal domain. Because the opposing globular domains remain spatially distant in both native and oxidatively modified CaM, the oxidative modification of methionines in the carboxyl-terminal domain are suggested to modify the conformation of the amino-terminal domain through alterations in the structural features involving the interdomain central helix. The structural basis for the linkage between oxidative modification and these global conformational changes is discussed in terms of possible alterations in specific noncovalent interactions that have previously been suggested to stabilize the central helix in CaM.

Kinetics of the "black hole" phenomenon in ultrasound backscattering measurements with red blood cell aggregation

The observation of a hypoechoic zone around the center of large tubes (the "black hole" phenomenon) in ultrasound backscattering measurements with red blood cell (RBC) aggregation was reported for the first time in 1989. Since then, a very limited number of studies tried to explain its complex mechanisms. In this study, blood models characterized by different RBC aggregation levels were prepared by diluting horse blood plasma with a saline solution in different proportions. A laser reflectometry technique was used to characterize the RBC aggregation kinetics and cohesion forces between RBCs for each blood sample. The blood was circulated in a 12.7 mm diameter vertical tube. For each experimental flow condition tested, 25 or 15 power Doppler ultrasound measurements were performed across the tube with a 10-MHz system and insonation angles varying between 40 degrees to 70 degrees. For flow rates varying between 100 and 1250 mL/min, the "black hole" was observed in most measurements performed with different aggregating RBC models. The "black hole" was more pronounced for RBCs with a high kinetics of aggregation and measurements with increasing Doppler angles. Previous studies suggested that this phenomenon is due to tube entrance effects, and the reduction of RBC aggregation at very low shear rates around the center of the tube. In the present study, the "black hole" was observed for shear rates up to 25 s(-1). It is suggested that the structural organization and orientation of RBC rouleaux may participate in the mechanism leading to the "black hole" phenomenon. A schematic representation of the rheological behavior of horse RBCs in a large tube under steady flow is presented.

Retroviral interleukin-7 gene transfer into human dendritic cells enhances T cell activation

Tumor vaccination with dendritic cells (DC) presenting tumor antigens to T cells is a promising approach in immunotherapy. The aim of this study was to enhance T cell stimulatory ability of human DC by retroviral expression of the interleukin-7 (IL-7) gene. IL-7 has been shown to provide a potent costimulatory signal for the proliferation of T cells and the generation of cytotoxic T cells (CTL). DC were generated from human peripheral blood mononuclear cells (PBMC). DC were analyzed by light- and electron-microscopy, immunophenotype (CD1a+, CD14-, CD80+, CD86+, HLA-DR+) and functional assays. According to these criteria, 75-85% of the cells were DC. The cells did not produce measurable amounts of IL-7 spontaneously nor did they express the IL-7 receptor. A retroviral IL-7 expression vector was constructed. Retroviral infection was performed with either the LXSN-hIL-7 vector of its variant LXSN. Using the LXSN-hIL-7 vector, IL-7 production of 2296 pg/10(6) cells/24 h could be achieved on average. Transduction of DC was confirmed by RT-PCR in a CD1a-enriched cell fraction. Transduction efficiency by a control virus coding for beta-galactosidase was about 30%. In autologous mixed lymphocyte reaction (MLR), IL-7 transduced DC augmented T cell proliferation by a factor of two compared with unmodified or mock-transfected DC, and in allogeneic MLR there was a 2.7-fold increase in T cell proliferation. The increase in T cell proliferation could be correlated to IL-7 secretion by DC. Dendritic cells that have been simultaneously peptide-loaded and gene-modified to secrete IL-7 are a potential tool to amplify activation of tumor-specific T cells.

Neutrophils but not eosinophils are involved in growth suppression of IL-4-secreting tumors

Local expression of IL-4 by gene-modified tumor cells increases their immunogenicity by inducing an inflammatory response that is dominated by eosinophils. Eosinophils have been implicated as antitumor effector cells because the application of a granulocyte-depleting Ab inhibited rejection of IL-4 transfected tumors. This Ab did not discriminate between eosinophils and neutrophils and, therefore, this experiment could not exclude neutrophils as primary effector cells, whereas eosinophils were innocent bystander cells in IL-4 transfected tumors. We analyzed tumor growth suppression and granulocyte infiltration in IL-5-deficient (IL-5(-/-)) mice that had a deficiency of eosinophils, using two tumor lines (B16-F10 and MCA205) transfected to secrete IL-4. IL-4-expressing tumors were at least as efficiently rejected in IL-5(-/-) mice as in wild-type mice, despite an almost complete absence of tumor-infiltrating eosinophils. However, neutrophils were present in undiminished amounts and their depletion partially restored tumor growth. Furthermore, the growth of IL-5-secreting tumors was not impaired in either wild-type or IL-5(-/-) mice, even though it induced eosinophilia in both mouse strains. These findings demonstrate that eosinophils can be induced in IL-5(-/-) mice by exogenous IL-5 and argue against a compensatory effect of neutrophils in the absence of eosinophils. We conclude that 1) infiltration of IL-4 transfected tumors by eosinophils is completely IL-5 dependent, 2) eosinophils have no tumoricidal activity, and 3) neutrophils are responsible, at least in part, for tumor suppression.

The research of myelinization of normal fetal brain with magnetic resonance imaging

OBJECTIVE

To investigate the growth and development of myelin of sheath fetal brain.

METHODS

Forty-four cases of pregnant women were imaged with magnetic resonance (MR) at 0.35 T (tesla). The signal changes of the main structures of fetal brain were analysed.

RESULTS

The signal intensity of cerebral (except basal ganglia) and cerebellar matter was hypo-signal on the T1WI (T1 weighted spin-echo image), iso-signal of the PDWI (Proton density weighted image) and hyper-signal on the T2WI (T2 weighted spin-echo image). As to the brain stem and basal ganglia, their signal intensities showed difference in different gestational weeks on T1WI. The intensities were of slight hypo-signal before and iso-signal after the 29th week. However, their signal intensities on PDWI and T2WI were the same as those of the cerebral and cerebellar matter.

CONCLUSIONS

There was no myelinization of fetal cerebral (except basal ganglia) and cerebellar matter during pregnant period. The myelin sheath was formed in the brain stem and basal ganglia after 29 gestational weeks. The process of myelinization began from brain stem to basal ganglia.

Reduced immunoreactivity to calcium-binding proteins in Purkinje cells precedes onset of ataxia in spinocerebellar ataxia-1 transgenic mice

Earlier we have shown alterations in immunoreactivity (IR) to the calcium-binding proteins parvalbumin (PV) and calbindin D-28k (CaB) in surviving Purkinje cells of patients with spinocerebellar ataxia-1 (SCA-1). In the present study we determined PV and CaB expression (by immunohistochemical and immunoblot analyses) in Purkinje cells of transgenic mice (TM) expressing the human SCA-1 gene with an expanded (line B05) and normal (line A02) CAG tract, as well as in age-matched nontransgenic mice (nTM). Heterozygotes in the B05 line develop progressive ataxia beginning around 12 weeks of age. A02 animals are phenotypically indistinguishable from wild-type (nontransgenic) animals. In the cerebella of 8-, 9-, and 12-week-old TM-B05 there was a progressive decrease in PV IR in Purkinje cells compared with nTM and TM-A02. Parvalbumin immunostaining in interneurons was well preserved in all groups. A progressive decrease was also observed in CaB IR in Purkinje cells of 8-, 9-, and 12-week-old TM-B05. Cerebellar Purkinje cells of 6-week-old TM-B05, which exhibit no ataxia and even lack demonstrable Purkinje cell loss, also revealed reduction in PV IR. This change was matched by a significant decrease in the amount of cerebellar PV in 6-week-old TM-B05 as determined by Western blot analysis. Calbindin D-28K immunohistochemistry did not detect any marked changes in CaB IR within Purkinje cells at 4 weeks. However, at 6 weeks immunostaining and immunoblot analysis revealed a significant decrease in CaB in TM-B05 compared with controls. These data suggest that decreased levels of calcium-binding proteins in Purkinje cells in SCA-1 transgenic mice may cause alteration in Ca2+ homeostasis.

Decreased conformational stability of the sarcoplasmic reticulum Ca-ATPase in aged skeletal muscle

Sarcoplasmic reticulum (SR) membranes purified from young adult (4-6 months) and aged (26-28 months) Fischer 344 male rat skeletal muscle were compared with respect to the functional and structural properties of the Ca-ATPase and its associated lipids. While we find no age-related alterations in (1) expression levels of Ca-ATPase protein, and (2) calcium transport and ATPase activities, the Ca-ATPase isolated from aged muscle exhibits more rapid inactivation during mild (37 degrees C) heat treatment relative to that from young muscle. Saturation-transfer EPR measurements of maleimide spin-labeled Ca-ATPase and parallel measurements of fatty acyl chain dynamics demonstrate that, accompanying heat inactivation, the Ca-ATPase from aged skeletal muscle more readily undergoes self-association to form inactive oligomeric species without initial age-related differences in association state of the protein. Neither age nor heat inactivation results in differences in acyl chain dynamics of the bilayer including those lipids at the lipid-protein interface. Initial rates of tryptic digestion associated with the Ca-ATPase in SR isolated from aged muscle are 16(+/- 2)% higher relative to that from young muscle. indicating more solvent exposure of a portion of the cytoplasmic domain. During heat inactivation these structural differences are amplified as a result of immediate and rapid further unfolding of the Ca-ATPase isolated from aged muscle relative to the delayed unfolding of the Ca-ATPase isolated from young muscle. Thus age-related alterations in the solvent exposure of cytoplasmic peptides of the Ca-ATPase are likely to be critical to the loss of conformational and functional stability.

[Study on HPV infection and p53 protein expression in laryngeal carcinoma]

In order to evaluate the role of human papillomavirus (HPV) infection and p53 protein expression in laryngeal squamous cell carcinoma (LSCC), the in situ hybridization and the labelled streptavidin biotin (LSAB) immunohistochemical method were used to detect the presence of HPV genomes 6B, 11, 16, 18 and expression of p53 protein respectively in 44 specimens of LSCC. And 16 specimens of laryngeal polyp were selected as controls.

RESULTS

1. HPV genomes 16/18 were detected in 19 (43.2%) of 44 LSCCs and in 2 (12.5%) of 16 laryngeal polyps (P < 0.05). 2.25 (56.9%) of 44 specimens of LSCC were p53 protein positive whereas the laryngeal polyps were all p53 negative. 3. 12 (63.2%) of 19 HPV 16/18 DNA-positive specimens of LSCC showed p53 protein expression and 12 (48%) of 25 p53 protein positive specimens of LSCC showed HPV 16/18 infection.

CONCLUSION

Expression of p53 protein and infection of HPV 16, 18 may play a role in carcinogenesis of LSCC, respectively or simultaneously.

Morphological characteristics and clinical significance of nerve distribution in pancreatic cancers

Macroscopic and immunohistochemical observations were made to clarify the innervation of normal pancreatic tissues, and the clinicopathological and electron-microscopic findings of 33 cases of pancreatic cancer were obtained. The results showed that the innervation of both the head and the body of the pancreas mainly consisted of nerve fibers separated from the right celiac neuroganglion and the right half of the superior mesenteric arterial plexus. The pancreas was full of nerve fibers ending at acinar lobules, among which the adrenergic nerves commonly control the walls of blood vessels. Pancreatic cancer tends to be accompanied by invasion and metastasis along intra or extra-pancreatic nerves, and we found that the positive rates for invasion and metastasis were 73.33% and 60.00%, respectively. The follow-up study revealed that the nerve-invasion group had worse prognosis than the non-invasion group (P < 0.05). The approaches of the invasions of the nerves were as follows: (1) through the vessels of the perineurium; (2) through the perineurium; and (3) through the synaptic membrane of nerve endings. The invasion were a continuous process, often resulting in the destruction or even the disappearance of the normal structure of the nerve fibers. The above results suggest that there are plentiful vegetative nerves inside or outside the pancreas and that pancreatic cancers have a tendency of invading and metastasizing along or around nerves.

Ultrasound backscattering from non-aggregating and aggregating erythrocytes--a review

The objective of the present paper is to provide a detailed review of theoretical, experimental and clinical works aimed at understanding the scattering of ultrasound by red blood cells (RBC). The paper focuses on the role of biofluid mechanics and blood biorheology on the scattering mechanisms. The influence of RBC aggregation on the ultrasound backscattered power is specifically addressed. After a short introduction, the paper presents the theory of Rayleigh scattering and summarizes theoretical models on ultrasound backscattering by RBC. The particle, continuum and hybrid models are presented along with reported packing factors used to consider the orderliness in the spatial arrangement of RBC. Computer models of ultrasound backscattering by RBC are also presented in this section. In the second section, experimental factors affecting the ultrasound backscattered power from blood are presented. The influence of the volume of the scatterers, ultrasound frequency, hematocrit, orientation of the scatterers, flow turbulence, flow pulsatility, and concentration of fibrinogen and dextran is discussed. The third section focuses on the use of ultrasound to characterize RBC aggregation. Three aspects are reported: the shear rate dependence of the backscattered power, the "black hole" phenomenon, and the kinetics of RBC rouleau formation. The fourth section reports in vivo observations of the "smoke like" echo in mitral valve disease, and blood echogenicity and backscattered power in veins and arteries. In the last section, new areas of research, clinical applications of ultrasound backscattering, and areas of potential future developments are presented.

Down-regulation of the expression and function of the transporter associated with antigen processing in murine tumor cell lines expressing IL-10

The MHC class I molecules present antigenic peptides to CTL. The peptides are delivered to the secretory pathway by TAP, which is formed by the association of MHC-encoded TAP1 and TAP2 gene products. Tumor cells incubated or transfected with IL-10 had decreased but peptide-inducible expression of MHC class I, decreased sensitivity to MHC class I-restricted CTL, and increased NK sensitivity. We here demonstrate that IL-10 expression in the murine lymphoma RMA inhibits the TAP-dependent translocation of peptides to the endoplasmic reticulum, resulting in accumulation of immature MHC class I molecules in the endoplasmic reticulum and subsequently low expression of cell surface MHC class I molecules. This finding is explained by a down-regulation of expression of TAP1 and TAP2, observed in IL-10-transfected RMA cells as well as in IL-10-transfected P815 mastocytoma cells. In the J558L plasmacytoma cell line, constitutively expressing high levels of IL-10, increased TAP-dependent translocation of peptides and expression of cell surface MHC class I could be induced by IL-10 antisense expression. IL-10 is the first example to demonstrate that a cytokine can decrease the expression and function of the TAP1/2 molecular complex and, in more general terms, the first example of a cytokine with an inhibitory effect on MHC class I-mediated Ag presentation.

Down-regulation of the expression and function of the transporter associated with antigen processing in murine tumor cell lines expressing IL-10

The MHC class I molecules present antigenic peptides to CTL. The peptides are delivered to the secretory pathway by TAP, which is formed by the association of MHC-encoded TAP1 and TAP2 gene products. Tumor cells incubated or transfected with IL-10 had decreased but peptide-inducible expression of MHC class I, decreased sensitivity to MHC class I-restricted CTL, and increased NK sensitivity. We here demonstrate that IL-10 expression in the murine lymphoma RMA inhibits the TAP-dependent translocation of peptides to the endoplasmic reticulum, resulting in accumulation of immature MHC class I molecules in the endoplasmic reticulum and subsequently low expression of cell surface MHC class I molecules. This finding is explained by a down-regulation of expression of TAP1 and TAP2, observed in IL-10-transfected RMA cells as well as in IL-10-transfected P815 mastocytoma cells. In the J558L plasmacytoma cell line, constitutively expressing high levels of IL-10, increased TAP-dependent translocation of peptides and expression of cell surface MHC class I could be induced by IL-10 antisense expression. IL-10 is the first example to demonstrate that a cytokine can decrease the expression and function of the TAP1/2 molecular complex and, in more general terms, the first example of a cytokine with an inhibitory effect on MHC class I-mediated Ag presentation.

Experimental polyneuropathy produced in guinea-pigs immunized against sulfatide

Antibodies to sulfatide are associated with polyneuropathy. To investigate the role of anti-sulfatide antibodies in this neurological disorder, guinea-pigs were immunized with sulfatide, and their behavior, serology and pathology were compared with animals injected with simple Freund's adjuvant. Eleven of 13 guinea-pigs that developed raised serum anti-sulfatide antibodies after five injections of sulfatide showed definite motor weakness. Demyelination of peripheral nerves and immunoglobulin deposits at peripheral nerve myelin sheath were found in symptomatic animals only. Functional impairment of the animals was significantly correlated with serum anti-sulfatide IgG levels and pathological findings in nerve fiber studies. Control animals and animals that received 1-3 injections of sulfatide were behaviorally and pathologically normal.

Extremely low awareness of AIDS, sexually transmitted diseases and condoms among Dai ethnic villagers in Yunnan province, China

OBJECTIVE

To assess the awareness of AIDS, other sexually transmitted diseases (STDs), condoms, sources of health information and HIV-related societal risks among Dai villagers in southern Yunnan Province, China.

SUBJECTS AND METHODS

In November-December 1994, a cross-sectional descriptive study, comprising a questionnaire-based survey and focus group discussions, was conducted in three Dai villages in Mengla county; a total of 177 Dai villagers were interviewed in the survey and eight focus group discussions were held. Ethnographic observations provided a composite picture of HIV risks in the area.

RESULTS

Only 18% of respondents had heard of AIDS, and only 25 and 28%, respectively, had heard of STDs or condoms. Furthermore, among these more aware groups, the level of knowledge was low and misconceptions were common. An ability to understand the official language (Mandarin) was the most important predictor of awareness of AIDS, other STDs or condoms. The sources of information in the three Dai villages sampled included TV, videos, radio and magazines, but only TV and videos had a large audience. Even so, these media were mostly in Mandarin and were not used in AIDS education. Travel outside of China was frequent; most villagers (77%) had traveled to Laos and 9% had traveled to Thailand. Societal risks of HIV transmission, such as an increasing incidence of STDs and an active sex industry, were observed in this area.

CONCLUSIONS

Dai villagers in southern Yunnan Province had an extremely low awareness and knowledge of AIDS, other STDs and condoms. Given the high mobility of ethnic villagers to neighboring countries in Southeast Asia and the societal risks of HIV transmission in this area, there is an urgent need to provide accessible education about AIDS and other STDs. Suggestions regarding such health education and the implications of HIV policy-making are discussed.

[Investigation of analytical methods of laser photothermal spectroscopy for trace microchemical analysis]

The purpose of this work is to investigate the analytical characteristics of laser photothermal spectroscopy and discuss the feasibility to performance trace microchemical analysis by analytical methods of laser photothermal spectroscopy.

Interleukin-10 prevents dendritic cell accumulation and vaccination with granulocyte-macrophage colony-stimulating factor gene-modified tumor cells

A wide variety of human tumors express IL-10 for reasons poorly understood. We have analyzed the effect of spontaneous IL-10 expression by a mouse tumor (J558L) on its immunoparalyzing effect. Because "cross-priming" of T cells by host Ag-presenting cells for MHC class I-restricted tumor Ags is a major pathway for induction of tumor immunity and that is enhanced by granulocyte-macrophage (GM) CSF, we expressed this cytokine in J558L cells. GM-CSF-secreting cells were not effective when used for immunization against challenge with the parental tumor. Inhibition of IL-10 expression through an IL-10 antisense retrovirus restored the vaccine efficacy of GM-CSF-producing J558L cells, demonstrating a direct role of IL-10 in paralyzing the GM-CSF-induced antitumor immune response. Since the tumor used for challenge produced IL-10, we conclude that IL-10 interfered primarily with the initiation but not the effector phase of the immune response. Immunohistochemical analysis of the vaccine site showed a GM-CSF-induced accumulation of dendritic cells (DC) (MHC class II+ and DEC-205+) in the absence of IL-10. In the presence of IL-10, DC accumulation was completely inhibited. Together, our results demonstrate an antagonistic effect of IL-10 with respect to GM-CSF-induced DC accumulation and tumor immunity and suggest a new mechanism by which tumors escape immune recognition: namely by preventing APC from obtaining access to tumor Ags.

Interleukin-10 prevents dendritic cell accumulation and vaccination with granulocyte-macrophage colony-stimulating factor gene-modified tumor cells

A wide variety of human tumors express IL-10 for reasons poorly understood. We have analyzed the effect of spontaneous IL-10 expression by a mouse tumor (J558L) on its immunoparalyzing effect. Because "cross-priming" of T cells by host Ag-presenting cells for MHC class I-restricted tumor Ags is a major pathway for induction of tumor immunity and that is enhanced by granulocyte-macrophage (GM) CSF, we expressed this cytokine in J558L cells. GM-CSF-secreting cells were not effective when used for immunization against challenge with the parental tumor. Inhibition of IL-10 expression through an IL-10 antisense retrovirus restored the vaccine efficacy of GM-CSF-producing J558L cells, demonstrating a direct role of IL-10 in paralyzing the GM-CSF-induced antitumor immune response. Since the tumor used for challenge produced IL-10, we conclude that IL-10 interfered primarily with the initiation but not the effector phase of the immune response. Immunohistochemical analysis of the vaccine site showed a GM-CSF-induced accumulation of dendritic cells (DC) (MHC class II+ and DEC-205+) in the absence of IL-10. In the presence of IL-10, DC accumulation was completely inhibited. Together, our results demonstrate an antagonistic effect of IL-10 with respect to GM-CSF-induced DC accumulation and tumor immunity and suggest a new mechanism by which tumors escape immune recognition: namely by preventing APC from obtaining access to tumor Ags.

Defining protein-protein interactions using site-directed spin-labeling: the binding of protein kinase C substrates to calmodulin

EPR spectroscopy was used to examine protein-protein interactions between calmodulin and spin-labeled peptides based on the protein kinase C substrate domains of the myristoylated alanine rich C kinase substrate (MARCKS) and neuromodulin. When bound to calmodulin, the C- and N-terminal ends of a 25 residue MARCKS derived peptide exhibited large amplitude motion on the nanosecond time scale and were accessible to paramagnetic agents in aqueous solution. However, residues 5-23 were highly protected and in contact with side chains from calmodulin. These data are consistent with an alpha-helical configuration for this segment of MARCKS and with structures that have been obtained for other calmodulin-substrate complexes. For the 17 residue neuromodulin derived peptide, which is Ca2+ independent in its binding to calmodulin, oxygen collision rates demonstrate that one helical face of this peptide interacts strongly with calmodulin. The data are consistent with an interaction of this face specifically with the C-terminal lobe of calmodulin, where this lobe is either in an "open" or "semiopen" configuration. The EPR data also indicate that the N-terminal lobe of calmodulin is in contact with the peptide, but that this lobe is not as strongly associated with the peptide target. Overall, the binding pocket for neuromodulin appears to be less compact and more dynamic than that formed by MARCKS. This behavior has not previously been seen for calmodulin substrates, and it may play a role in the Ca2+ independent binding of this class of substrates. This work demonstrates the utility of EPR spectroscopy to define protein-protein interactions; in addition, oxygen collision frequencies obtained at buried sites appear to provide information on the conformational dynamics of proteins.

Effect of prostatic growth factor, basic fibroblast growth factor, epidermal growth factor, and steroids on the proliferation of human fetal prostatic fibroblasts

To study the relationship between androgen metabolism and the pathogenesis of benign prostatic hypertrophy, we purified a growth factor from benign hyperplastic tissue of human prostates and assayed the proliferative responses of human fetal prostatic fibroblasts to the purified growth factor (hPGF), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), dihydrotestosterone (DHT), and estradiol (E2). Prostatic tissue extracts were fractionated using heparin-Sepharose chromatography. The fraction that eluted with 1.3-1.7 M NaCl contained the majority of mitogenic activity. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS/PAGE) of the lyophilyzed active fraction showed a band at 17,000 daltons. Human prostatic fibroblasts were isolated from fetal prostate and tested for their proliferative responses to hPGF, bFGF, EGF, DHT, and E2. hPGF, as well as bFGF and EGF, did increase tritiated thymidine incorporation into the cultured fibroblasts. DHT(10(-7) M) had a significant stimulatory effect on cell growth in serum-free media after 6 days of culture. E2(10-7 M) had no effect on cell proliferation. The combination of DHT and E2 showed no synergistic effect. We conclude that our purified hPGF, bFGF, and EGF promote cell growth directly, DHT indirectly, while E2 does not. The effect of DHT appears to be mediated via the increased production and/or secretion of growth factor(s). Possibly, the bFGF-like hPGF purified from human benign hyperplastic prostatic tissue is such a mediator.

Power Doppler ultrasound evaluation of the shear rate and shear stress dependences of red blood cell aggregation

The use of power Doppler ultrasound at 10 MHz is evaluated as a method to study the shear rate and the shear stress dependences of red blood cell aggregation. This evaluation was based on six in vitro experiments conducted in a 1.27-cm diameter tube under steady flow conditions. Porcine whole blood was circulated in the flow model at flow rates ranging between 125 to 1500 ml/min (mean shear rate across the tube ranging between 6 and 74 s-1). For each flow condition, the variation of the Doppler power across the tube and the velocity profile were measured by moving the Doppler sample volume across the tube diameter. For each radial position, the shear rate within the Doppler sample volume was also determined by considering the radial power pattern of the ultrasound beam. To estimate the shear stress within the Doppler sample volume, the apparent viscosity of blood samples withdrawn from the flow model was measured for each experiment. The variation of the Doppler power as a function of the shear rate within the sample volume showed a rapid reduction of the power between 1 and 5 s-1, a transition region between 5 and 10 s-1, and a very slow reduction beyond 10 s-1. Little variation of the Doppler power was measured for shear stress higher than 2 dyn/cm2. The maximum Doppler power for all flow rates was usually found near the center of the tube. Based on the ultrasonic scattering models, which predict that the Doppler power is related to the volume square of the scatterers, the method described in the present study showed a very high sensitivity to the presence of red blood cell aggregation for shear rates below 10 s-1.

Effect of Eimeria tenella infection on the production of Salmonella enteritidis-contaminated eggs and susceptibility of laying hens to S. enteritidis infection

Experiments were conducted to determine the effect of Eimeria tenella infection on the production of Salmonella enteritidis-contaminated eggs and susceptibility of egg-laying hens to S. enteritidis infection. The dose of sporulated oocysts of E. tenella used in the present study was 2 x 10(5) per chicken. When hens were infected with 10(6) colony-forming units (CFU) of S. enteritidis, E. tenella infection resulted in a significant increase (P < 0.05) of S. enteritidis contamination in the shells of fresh eggs but not in the egg contents of fresh eggs and stored eggs. Significant effects of coccidial infection on the contamination of eggs (shells and contents) were not observed when hens were infected with 10(4) CFU of S. enteritidis. Surface-disinfected eggs pooled within each week from individual chickens infected with 10(4) CFU of S. enteritidis and E. tenella showed significantly (P < 0.05) more S. enteritidis contamination in eggshells, but not in egg contents, than did those from hens infected with S. enteritidis alone. Coccidial infection resulted in a significant increase of S. enteritidis in the cloacal swabs of hens infected with 10(4) CFU of S. enteritidis. In all the experiments, chickens infected with S. enteritidis and E. tenella showed significantly higher positive rates and counts of cecal S. enteritidis than did chickens infected with S. enteritidis alone. No significant differences of S. enteritidis-positive rates in ovary, oviduct, liver, and spleen were noted whether the hens were infected with a combination of E. tenella and S. enteritidis or with S. enteritidis alone.

Membrane structure of protein kinase C and calmodulin binding domain of myristoylated alanine rich C kinase substrate determined by site-directed spin labeling

Cysteine-substituted peptides based on the membrane, calmodulin, and protein kinase C binding domain of the myristoylated alanine rich C kinase substrate (MARCKS) were synthesized and derivatized with a sulfhydryl reactive proxyl nitroxide. These spin-labeled peptides were used in combination with continuous wave power saturation electron paramagnetic resonance (EPR) spectroscopy to determine the position and structure of the peptide on membranes containing phosphatidylserine. These peptides bind at the membrane interface, with nitroxide side chains in the central and C-terminal regions lying several angstroms below the level of the head group. In contrast, the N-terminus of the peptide is extended out of the membrane interface so that the two N-terminal residues are positioned on the aqueous side of the head group. When bound to the membrane, the N-terminal segment of this peptide is sensitive to the membrane surface charge density. Higher charge densities decrease the amplitude of side chain motions at the N-terminus and bring this end of the peptide closer to the membrane interface. When the location of successive residues along the bilayer normal is compared, no helical trend is seen, and no evidence for aggregation of the peptide is found. The EPR spectra of double spin-labeled peptides also show no evidence for a helical structure. Thus, these basic peptides are in an extended configuration at the membrane interface with hydrophobic side chains oriented inward toward the membrane hydrocarbon.

Group II intron ribozymes that cleave DNA and RNA linkages with similar efficiency, and lack contacts with substrate 2'-hydroxyl groups

BACKGROUND

Group II introns are self-splicing RNAs that have mechanistic similarity to the spliceosome complex involved in messenger RNA splicing in eukaryotes. These autocatalytic molecules can be reconfigured into highly specific, multiple-turnover ribozymes that cleave oligonucleotides in trans. We set out to use a simplified system of this kind to study the mechanism of cleavage.

RESULTS

Unlike other catalytic RNA molecules, the group II ribozymes cleave DNA linkages almost as readily as RNA linkages. One ribozyme variant cleaves DNA linkages with an efficiency comparable to that of restriction endonuclease EcoRI. Single deoxynucleotide substitutions in the substrate showed that the ribozymes bind substrate without engaging 2'-hydroxyl groups.

CONCLUSIONS

The ribose 2'-hydroxyl group at the cleavage site has little role in transition-state stabilization by group II ribozymes. Substrate 2'-hydroxyl groups are not involved in substrate binding, suggesting that only base-pairing is required for substrate recognition.

Four outbreaks of human trichinellosis in Henan Province

Four outbreaks of human trichinellosis caused by eating pork together had occurred successively in two rural areas and two cities of Henan Province, where the disease is endemic. Of the 110 persons involved, 54 had the onset. All of them had the history of eating pork. In the outbreak of Dengzhou, in those persons who dined together, men were all uninfected and 13 women were infected. The difference found between sexes was suggested to be related with spirit drinking. In these 54 patients, the latent period ranged from 3 to 28 days. The relevant clinical symptoms and signs were fever, edema, myalgia, rash, headache, nausea, abdominal pain and diarrhea. Vomiting was uncommon. Most patients were hospitalized and all cases recovered in two weeks after proper treatment with albendazole.

Tumor growth inhibition mediated by lymphotoxin: evidence of B lymphocyte involvement in the antitumor response

The antitumor effect of lymphotoxin (LT) and the underlying cellular mechanism were analyzed. To achieve an increased local concentration of LT at the site of tumor growth, which mimics the physiological fashion of cytokine action, we transfected the murine plasmacytoma J558L cells with a human LT expression plasmid and selected several clones that produce varying levels of LT for analysis of their tumorigenicity. The LT produced by the transfected J558L cells effectively suppressed tumor growth in syngeneic BALB/c mice without any obvious side effects. This antitumor function is indirect and LT specific, because the tumor cells did not show altered growth kinetics after the gene transfer in vitro, and tumor growth inhibition in vivo could partially be reversed by an anti-LT mAb. In nude mice, LT producing tumors were initially suppressed, but most mice developed a tumor at the end of the study. However, the requirement of T cells for complete tumor rejection could be compensated for by higher amounts of LT secretion. Furthermore, the antitumor activity of LT seems to involve B lymphocytes in the absence of functional T lymphocytes since a significant difference existed between tumor growth of J558-LT cells in nude and in SCID mice. LT-producing tumors but not parental tumors were massively infiltrated by B220+ cells in nude mice. The secretion of LT by tumor cells also induced a heavy infiltration of Mac-1+ and Mac-3+ cells and a moderate infiltration of Gr-1+ cells, both in nude and in SCID mice. Together, LT-producing J558L cells are rejected by a complex immunological mechanism, which seems to involve T as well as B and other cells. This distinguishes LT from a number of other cytokines analyzed in analogous experiments.

Human lymphotoxin has at least equal antitumor activity in comparison to human tumor necrosis factor but is less toxic in mice

Because of the severe toxicity of systemically applied tumor necrosis factor (TNF) in cancer patients, considerable efforts have been made to construct mutant TNF molecules, which retain antitumor activity, but display less toxicity. We compared tumor suppression in relation to the toxic effects of human TNF and human lymphotoxin (LT) in mice. The genes for these two cytokines were expressed in Chinese hamster ovary (CHO) cells. Intraperitoneal injection of parental and gene modified CHO cell lines producing similar amounts of biologically active TNF or LT, respectively, into nude mice showed that CHO-TNF cells killed the mice more rapidly than parental cells, but that CHO-LT tumor bearing mice lived significantly longer than mice injected with parental cells. Injection of the cells subcutaneously into severe combined immunodeficiency (SCID) mice allowed direct comparison of tumor suppression and toxic effects of the two cytokines. Both TNF and LT produced by the tumor effectively suppressed tumor growth by an indirect mechanism, LT being at least as effective as TNF. However, mice bearing CHO-TNF cells either died rapidly or developed cachexia, as shown by weight loss. In contrast, mice injected with CHO-LT cells never rapidly died and became cachectic much later than CHO-TNF cell injected animals, though serum levels of LT were higher than those of TNF. Analysis of soluble forms of TNF receptors (TNF-R1 and TNF-R2) in sera of tumor bearing mice showed that soluble TNF-R1 was downregulated in both CHO-TNF and CHO-LT, in comparison with CHO-neo cell injected mice and to normal SCID mice. The soluble form of TNF-R2 was induced by CHO cell lines. In CHO-TNF cell injected SCID mice, serum levels were significantly increased, whereas in mice injected with CHO-LT cells, serum levels of soluble TNF-R2 were decreased. Together, our results show a higher therapeutic index of LT compared with TNF.

Anesthetics reduce the magnitude of the membrane dipole potential. Measurements in lipid vesicles using voltage-sensitive spin probes

Lipid membranes possess a large internal dipole potential that greatly exceeds the magnitude of typical transmembrane or surface potentials. The volatile general anesthetics, halothane, isoflurane and enflurane were tested by the use of positively and negatively charged hydrophobic ion spin labels in lipid bilayer vesicles for their ability to modulate the membrane dipole potential. These anesthetics decreased the binding of negatively charged hydrophobic ion spin probes based on trinitrophenol, but increased the binding of positively charged hydrophobic ion probes based on triphenylalkylphosphoniums. They also enhanced the transit rates for both hydrophobic anions and cations; however, translocation rates were enhanced to a greater extent for the cation probes compared to the anion probes. The changes in binding constant for cations versus anions could be accurately accounted for using a simple model for the free energy profile for hydrophobic ions across membranes, and indicate that these anesthetics decrease the membrane dipole potential. From a fit of the experimental data to this model, anesthetics could promote a decrease in the dipole potential in two ways. First, anesthetics appear to modify the effective dipole moment in the membrane interface and may accomplish this by orienting their molecular dipole antiparallel to the intrinsic dipoles at the interface. Second, they modify the membrane dielectric constant, leading to a decrease in the field across the interface. At equivalent membrane concentrations, isoflurane, enflurane, and halothane produced similar changes in the dipole potential and decreased the dipole potential as much as 65 mV at a membrane mole fraction of 0.20.(ABSTRACT TRUNCATED AT 250 WORDS)

Advances in biopharmaceutical analysis in the People's Republic of China: 1991-1993

The methodological studies on biopharmaceutical analysis of drugs and their metabolites by liquid and gas chromatography with various detectors have been reviewed. Research articles were selected from well known journals published in the People's Republic of China between January 1991 and March 1993. The applications of these methods in bioavailability, pharmacokinetics, therapeutic drug monitoring and metabolic studies have also been discussed.

[Treatment of maxillofacial vascular malformation by arterial embolism and application of sclerosing agent]

30 cases of large cavernous and racemose hemangioma of the maxillofacial were treated selectively with arterial embolism of the tumor and inject Xiaozhiling into the tumor, from November 1990 to November 1993. This method has exact effect either to racemose or to cavernous hemangioma, without facial defect and functional damage. All the patients were followed up 6 months to 3 years. 27 cases were cured, 1 failed, 1 gave up treatment, 1 died of complication. Its mechanism, indications, prevention of complications and recurrence were discussed.

Fast purification of Phaseolus vulgaris isolectins

Phytohemagglutinin from red kidney bean has been purified by affinity chromatography on a human alpha 1-acid glycoprotein Sepharose 4B column. Further purification of the hemagglutinin's five isolectins was achieved on a Mono S column with an 86% protein recovery. Each sequentially eluted isolectin from the ion exchange column displayed either hemagglutinating or mitogenic activity. The main activity of each fraction was the result of the combination of varying proportions of the L and E subunits.

Development of a gene cloning system for Streptomyces hygroscopicus subsp. yingchengensis, a producer of three useful antifungal compounds, by elimination of three barriers to DNA transfer

Streptomyces hygroscopicus 10-22 could not be transformed with any of the commonly used Streptomyces plasmid vectors and was resistant to plaque formation by the Streptomyces phages phi C31 and R4. Repeated selection resulted in the isolation of derivatives of S. hygroscopicus 10-22 that could be transformed with pIJ101- and pJV1-derived cloning vectors and of restriction-deficient derivatives that could accept DNA propagated in Streptomyces lividans 66. These new strains, which include three that still produce the original antibiotics, can be used as hosts for gene cloning. Insertion of nonreplicating vectors by homologous recombination and transposition of Tn4560 were demonstrated in S. hygroscopicus 10-22.