Three-dimensional microscopy data exploration by interactive volume visualization

This paper presents a new volume visualization approach for three-dimensional (3-D) interactive microscopy data exploration. Because of their unique image characteristics, 3-D microscopy data are often not able to be visualized effectively by conventional volume visualization techniques. In our approach, microscopy visualization is carried out in an interactive data exploration environment, based on a combination of interactive volume rendering techniques and image-based transfer function design methods. Interactive volume rendering is achieved by using two-dimensional (2-D) texture mapping in a Shear-Warp volume rendering algorithm. Image processing techniques are employed and integrated into the rendering pipeline for the definition and searching of appropriate transfer functions that best reflect the user's visualization intentions. These techniques have been implemented successfully in a prototype visualization system on low-end and middle-range SGI desktop workstations. Since only 2-D texture mapping is required, the system can also be easily ported to PC platforms.

[Synthesis and characterization of the solid complexes of Ni(II), Cu(II) and Zn(II) nitrates with norfloxacin]

Three solid complexes of Ni (II), Cu (II) and Zn (II) nitrates with norfloxacin, having the composition of [Ni (NFA)2 (NO3)] NO3.2H2O, [Ca (NFA)2] (NO3)2.H2O, [Zn (NFA)2 (NO3)] NO3.2H2O, have been synthesized in aqueous solvent. All the isolated complexes have been characterized by elemental analysis, IR spectra, thermogravimetric analysis and molar conductance in methanol. The results show that [Ni (Ni (NFA)2) (NO3)] NO3.2H2O, [Zn (NFA)2 (NO3)] NO3.2H2O are 1:1 tape electrolytes in methanol, their coordination numbers are all 6. The nitrates of inner boundary are all bidenlate ligands. The complex torming with copper nitrate and norfloxacin is non-electrolyte in methanol, the coordination number is 4. Norfloxacin molecules with inner salt types are all bidenlate ligands.

[Effect of acute hypobaric hypoxia on renal function and structure in rats]

OBJECTIVE

To observe renal damage due to acute hypobaric hypoxia.

METHOD

Thirty-six male wistar rats were randomly divided into three groups A, B and C (n = 12 for each). Group A served as control, while groups B and C were exposed to 5000 m altitude for 30 min. Sample of serum and renal tissues were taken from group B rats 20 min and from group C rats 24 h after the exposure respectively.

RESULT

Serum ureanitrogen (BUN) and creatinine (Crea) increased significantly in group B and C rats after exposure to hypoxia (P< 0.01). Cl- and alkaline phosphatase (AKP) in serum also increased (P < 0.05), but renal endothelin (ET) decreased significantly (P < 0.01). All changes in group C rats tended to recover to normal level, except Cl- which continued to increase. Dilation of renal vessels was found under optic-microscope, and pathological changes were found in mitochondra and epithelial cells.

CONCLUSION

Acute hypobaric hypoxia might be harmful to renal function and structure.

Inactivation of cysteine proteases by (acyloxy)methyl ketones using S'-P' interactions

We have synthesized (acyloxy)methyl ketone inactivators of papain, cathepsin B, and interleukin-1beta conversion enzyme (ICE) that interact with both the S and S' subsites. The value of k(inact)/K(i) for these inactivators is strongly dependent on the leaving group. For example, Z-Phe-Gly-CH(2)-X is a poor inactivator of papain when X is OCOCH(3) (k(inact)/K(i) = 2.5 M(-)(1) s(-)(1)) but becomes a potent inactivator when X is OCO-L-Leu-Z (k(inact)/K(i) = 11 000 M(-)(1) s(-)(1)). Since these leaving groups have similar chemical reactivities, the difference in potency must be attributed to interactions with the S' sites. The potency of the leaving group correlates with the P' specificity of papain. Similar results are also observed for the inactivation of cathepsin B by these compounds. A series of inactivators with the general structure Fmoc-L-Asp-CH(2)-X were designed to inactivate ICE. No inhibition was observed when X was OCOCH(3). In contrast, ICE is inactivated when X is OCO-D-Pro-Z (k(inact)/K(i) = 131 M(-)(1) s(-)(1)). These results demonstrate that S'-P' interactions can be utilized to increase the efficacy and selectivity of (acyloxy)methyl ketone inactivators.

Specific regulation of CENP-E and kinetochores during meiosis I/meiosis II transition in pig oocytes

To understand the mechanisms which regulate meiosis-specific cell cycle and chromosome distribution in mammalian oocytes, the level and the localization of CENP-E and the kinetochore number and direction on a half bivalent were examined during pig oocyte maturation. CENP-E is a kinetochore motor protein whose intracellular level and localization are strictly regulated in the somatic cell cycle. The localizations of CENP-E on meiotic chromosomes from diakinesis stage to anaphase I and at the spindle midzone at telophase I were shown by immunofluorescent confocal microscopy to be similar to those in somatic cells of pig and other species. Further, ultrastructural analysis revealed the presence of CENP-E on fibrous corona and outer plate of kinetochores of the meiotic chromosomes. However, unlike mitosis, CENP-E staining was continuously detected either at the spindle midzone or on the kinetochores of segregated chromosomes during the first polar body emission. Consistent with this, immunoblot analysis revealed that CENP-E level remained high during meiosis I/meiosis II (MI/MII) transition and that some of CENP-E survived through the transition even in cycloheximide-treated oocytes in which cyclin B1 was completely degraded. Furthermore, examinations of CENP-E signals in confocal microscopy and kinetochores in electron microscopy in MI and MII oocytes provide the cytological evidence in mammalian oocytes which suggests that each sister chromatid in a pair has its own kinetochore which localizes side-by-side so that two sister chromatids on a half bivalent are oriented toward and connected to the same pole in MI.

Degradation of pig cyclin B1 molecules precedes MAP kinase dephosphorylation during fertilisation of the oocytes

Pig oocytes at metaphase II were activated by penetration of spermatozoa in cycloheximide-free and cycloheximide-containing fertilisation media. The precise nuclear stage, and the kinetics of degradation of cyclin B1 and dephosphorylation of MAP kinase were assessed after insemination. After maturation culture, 96% of oocytes reached metaphase II. At 6 h after insemination in cycloheximide-free medium, 68% of the oocytes were activated and had progressed to anaphase II or beyond. After 8 h, 89% of the oocytes were activated: a female pronucleus had formed and the heads of penetrating spermatozoa had enlarged and changed to male pronuclei. In the cycloheximide-containing medium, activation of oocytes started earlier than in cycloheximide-free medium. After 4 h, 43% of the oocytes were activated, and the percentage increased to 97% after 6 h. Pig cyclin B1 disappeared in the oocytes at 6 h after insemination in both cycloheximide-containing and cycloheximide-free media. Pig oocytes at metaphase II contained two types of MAP kinase--ERK 1 and ERK 2--in their active phosphorylated forms. At 8 h after insemination ERK 2 changed to the fast-migrating inactive form in the oocytes cultured in both cycloheximide-containing and cycloheximide-free media, although the shift-down was not complete. The change was delayed by 2 h after the degradation of cyclin B1 molecules. These results demonstrate that degradation of pig cyclin B1 molecules corresponds to the transition of the oocytes from metaphase II arrest to anaphase II/telophase II and was followed by MAP kinase dephosphorylation.

[The past, current status and future of general practice and community health service in China]

Some basic concepts of general practice and community health service are introduced briefly in this paper, as well as their past, current status and future. Issues existed in general practice and community health service at present are also discussed. In fact, general practice and community health service have existed in China for a long time since 1920s. The urgency and possibility for development of general practice and community health service in China are analyzed. Suggestions for three issues relevant to their development are put forward.

[Relation of GFR and endothelin in the plasma in pilots and ground crew]

OBJECTIVE

To observe the specitic property of Glomeoular Filtration Rate (GFR) and its relation to endothelin of plasma in pilots.

METHOD

GFR was assessed with single photon emisson computed tomography (SPECT), tracer for 99mTc-DTPA, enthlion of plasma were measured by radio immunossay in forty-six pilots, thirty ground crew and renal disease patients.

RESULT

Endothelin were not correlation with GFR in pilots. GFR of pilots and ground crew had not a significant difference. Compared with ground crew and pilots, endothelin of renal disease patients had a significant increased, and GFR had a significant decreased. Age were a linear negative correlation with total GFR r = (0.84, P < 0.01), flying time, age had not correlation with endothelin. After thirty-one ground endothelin had a significant difference with ground crew.

CONCLUSION

It suggested that the endothelin has no influence on GFR in pilots when it was increased with in the limits of a level, pilots and ground crew may use the same stand on GFR.

Suppression of neuropeptides' mRNA expression by herbal medicines in a rat model of peripheral inflammation

The traditional Chinese medicines have been used clinically for a long time in some Asian countries, however, very few studies have been done to demonstrate the working mechanisms of these medicines using recently developed biochemical methodologies. In this study, we examined the anti-inflammatory effect of Huang-Lian-Jie-Du-Tang (HLJDT), a combination of herbs used in traditional Chinese medicine, on paw edema, thermal hyperalgesia and the mRNA increase of neuropeptides in spinal dorsal horn and hypothalamic neurons using a rat model of peripheral inflammation and hyperalgesia. The rats that received HLJDT from 3 days before the injection of complete Freund's adjuvant (CFA) into the plantar had significantly less edema and reduced thermal hyperalgesia compared to control rats that received CFA injection. The up-regulation of preprodynorphin mRNA in L4-5 dorsal horn neurons 8 hours after CFA injection that was observed in control rats, was also decreased in the HLJDT-treated rats. Moreover, there was a significant decrease in mRNA level of corticotropin-releasing factor in the paraventricular hypothalamic nucleus in the HLJDT-treated rats. These data demonstrate that HLJDT is anti-inflammatory, and produces changes in mRNA expression in dorsal horn and hypothalamic neurons. This is the first demonstrated that a traditional Chinese medicine can affect the excitability of neurons through an anti-inflammatory action.

Selective requirement for Cdc25C protein synthesis during meiotic progression in porcine oocytes

Fundamental differences between meiosis and mitosis suggest that the shared central cell cycle machinery may be regulated differently during the two division cycles. This paper focuses on unique features of Cdc25C protein function during meiotic progression. We report on the existence of oocyte-specific CDC25C transcripts that differ from their somatic counterparts in the 3' untranslated region. While CDC25C mRNA levels remain constant in fully-grown oocytes, corresponding protein levels increase progressively during maturation to a maximum at metaphase II. Elevation of Cdc25C protein levels in G2-oocytes by mRNA injection failed to increase MPF-kinase levels or to induce premature entry into M-phase. Likewise, antisense-induced arrest of translation (translational arrest) had no effect on chromosome condensation, nucleolar disassembly, or nuclear membrane contraction. By contrast, translational arrest inhibited subsequent events including membrane disassembly and spindle formation. Neither up- nor down-regulation of Cdc25C synthesis after metaphase I plate formation influenced progression to metaphase II. However, translational arrest during metaphase resulted in incomplete chromosome decondensation and abnormal pronuclear membrane assembly after activation. We conclude that Cdc25 protein, translated from unique transcripts, is preferentially located in the oocyte nucleus and is essential for progress through late diakinesis. Subsequently, new synthesis of Cdc25C protein is required for the orderly transition from meiotic to mitotic cell division.

Dorsal column-thalamic pathway is involved in thalamic hyperexcitability following peripheral nerve injury: a lesion study in rats with experimental mononeuropathy

A total of 68 neurons were recorded from the ventro-postero-lateral nucleus of thalamus (VPL) in rats with a unilateral chronic constriction injury (CCI) of the sciatic nerve (n=20), sham operation (n=24) and naive rats (n=24), and effects of the lesion of dorsal column (DC) pathway [DC lesion or DC+gracile nucleus lesions] on VPL nucleus neuronal activities were studied. In the VPL nucleus contralateral to the CCI (receiving input from the injured nerve), response latencies of low threshold mechanoreceptive (LTM) and wide dynamic range (WDR) neurons to electrical stimulation of the sciatic nerve were significantly longer than that in the contralateral VPL nucleus receiving input from the sham-operated side (P<0.05). In contrast, response latencies of LTM and WDR neurons to DC stimulation were not different between the sham operated and CCI sides (0.05). Background activity of WDR neurons was significantly higher in the VPL nucleus contralateral to the CCI side when compared to neurons in the VPL nucleus contralateral to the sham operated side and in naive animals. Responses of LTM and WDR neurons to innocuous mechanical stimulation of the receptive fields were significantly decreased after DC and DC+gracile nucleus lesions in all animals. However, the responses of WDR neurons to noxious stimuli were selectively reduced only in rats with CCI by DC and DC+gracile nucleus lesions (P<0.05). The decrease in noxious stimulus-evoked responses of WDR neurons in the VPL nucleus contralateral to the CCI side after DC and DC+gracile nucleus lesions was greater than that in the VPL nucleus contralateral to the sham operated side and naive animals. These results indicated that DC and DC+gracile nucleus lesions produced selective and stronger effect on noxious responses of VPL nucleus WDR neurons receiving input from the site of nerve injury. The findings suggest that the gracile nucleus-thalamic pathway conveys, or modulates, nociceptive information to the VPL nucleus following peripheral nerve injury, resulting in an increase in VPL nucleus response to noxious stimuli that contributes to the development of mechanical hyperalgesia.

Deficiency in fatty acid synthase leads to premature cell death and dramatic alterations in plant morphology

An Arabidopsis mosaic death1 (mod1) mutant, which has premature cell death in multiple organs, was isolated. mod1 plants display multiple morphological phenotypes, including chlorotic and curly leaves, distorted siliques, premature senescence of primary inflorescences, reduced fertility, and semidwarfism. The phenotype of the mod1 mutant results from a single nuclear recessive mutation, and the MOD1 gene was isolated by using a map-based cloning approach. The MOD1 gene encodes an enoyl-acyl carrier protein (ACP) reductase, which is a subunit of the fatty acid synthase complex that catalyzes de novo synthesis of fatty acids. An amino acid substitution in the enoyl-ACP reductase of the mod1 mutant causes a marked decrease in its enzymatic activity, impairing fatty acid biosynthesis and decreasing the amount of total lipids in mod1 plants. These results demonstrate that a deficiency in fatty acid biosynthesis has pleiotropic effects on plant growth and development and causes premature cell death.

Deficiency in fatty acid synthase leads to premature cell death and dramatic alterations in plant morphology

An Arabidopsis mosaic death1 (mod1) mutant, which has premature cell death in multiple organs, was isolated. mod1 plants display multiple morphological phenotypes, including chlorotic and curly leaves, distorted siliques, premature senescence of primary inflorescences, reduced fertility, and semidwarfism. The phenotype of the mod1 mutant results from a single nuclear recessive mutation, and the MOD1 gene was isolated by using a map-based cloning approach. The MOD1 gene encodes an enoyl-acyl carrier protein (ACP) reductase, which is a subunit of the fatty acid synthase complex that catalyzes de novo synthesis of fatty acids. An amino acid substitution in the enoyl-ACP reductase of the mod1 mutant causes a marked decrease in its enzymatic activity, impairing fatty acid biosynthesis and decreasing the amount of total lipids in mod1 plants. These results demonstrate that a deficiency in fatty acid biosynthesis has pleiotropic effects on plant growth and development and causes premature cell death.

Activating transcription factor 3 (ATF3) induction by axotomy in sensory and motoneurons: A novel neuronal marker of nerve injury

Activating transcription factor 3 (ATF3), a member of ATF/CREB family of transcription factors, is induced in a variety of stressed tissue. ATF3 regulates transcription by binding to DNA sites as a homodimer or heterodimer with Jun proteins. The purpose of this study was to examine the expression and regulation of ATF3 after axonal injury in neurons in dorsal root ganglia (DRG) and spinal cord. In naive rats, ATF3 was not expressed in the DRG and spinal cord. Following the cut of peripheral nerve, ATF3 was immediately induced in virtually all DRG neurons and motoneurons that were axotomized, and the time course of induction was dependent on the distance between the injury site and the cell body. Double labeling using immunohistochemistry revealed that the population of DRG neurons expressing ATF3 included those expressing c-jun, and in motoneurons ATF3 and c-jun were concurrently expressed after axotomy. In contrast to c-jun, ATF3 was not induced transsynaptically in spinal dorsal horn neurons. We conclude that ATF3 is specifically induced in sensory and motoneurons in the spinal cord following nerve injury and should be regarded as an unique neuronal marker of nerve injury in the nervous system.

Sustained high-level expression of full-length human factor VIII and restoration of clotting activity in hemophilic mice using a minimal adenovirus vector

The successful prophylactic treatment of hemophilia A by frequent infusions of plasma concentrates or recombinant factor VIII (hFVIII) indicates that gene therapy may be a potential alternative for the treatment of the disease. For efficient delivery and long-term expression of the hFVIII gene, a novel minimal adenovirus (mini-Ad) vector, MiniAdFVIII, has been developed. The vector is devoid of all viral genes and carries the full-length hFVIII cDNA under the control of the human 12.5-kb albumin promoter. The MiniAdFVIII vector was propagated with the assistance of an ancillary vector in 293 cells and was purified by CsCl banding. Sustained expression of hFVIII at physiologic levels (100-800 ng/mL) was achieved in mice after a single intravenous injection of MiniAdFVIII. The expressed hFVIII had a structure identical to that of recombinant hFVIII, as determined by Western blot analysis. The functionality of the protein was confirmed by the restoration of blood coagulation capacity in MiniAdFVIII-treated hemophilic mice, as determined by tail clipping observations. Although antivector or antihuman FVIII antibodies at various levels were detected, long-term expression of the transgene was observed in the mice that did not generate antibodies against the transgene product. The vector DNA persisted in the liver tissues of the mice with long-term expression. No significant histopathologic findings or toxicities were observed to be associated with the vector in the MiniAdFVIII-treated C57BL/6 mice. These results support the further development of MiniAdFVIII for clinical trials toward the treatment of hemophilia A.

Differential effect of brain-derived neurotrophic factor on high-threshold mechanosensitivity in a rat neuropathic pain model

We investigated the effect of the systemic infusion of brain derived neurotrophic factor (BDNF) on the behavioral response in a rat neuropathic pain model. One microgram per hour infusion of BDNF significantly attenuated mechanical hyperalgesia tested by the pin-prick test, however, 20 microg/h-BDNF infusion, on the contrary, enhanced the response. Neither 0.5 nor 10 microg/h-BDNF infusion influenced the mechanical hyperalgesia. Mechanical allodynia and thermal hyperalgesia, tested using a von Frey filament (23.0 mN) and the plantar test, were not influenced by BDNF treatment. These data suggest that systemic BDNF treatment can specifically alter high-threshold mechanosensitivity.

Lipopolysaccharide-induced biliary factors enhance invasion of Salmonella enteritidis in a rat model

In this study, the role of the hepatobiliary system in the early pathogenesis of Salmonella enteritidis infection was investigated in a rat model. Intravenous (i.v.) challenge with lipopolysaccharide (LPS) has previously been shown to enhance the translocation of normal gut flora. We first confirmed that LPS can similarly promote the invasion of S. enteritidis. Oral infection of outbred Australian Albino Wistar rats with 10(6) to 10(7) CFU of S. enteritidis led to widespread tissue invasion after days. If animals were similarly challenged after intravenous administration of S. enteritidis LPS (3 to 900 microg/kg of body weight), significant invasion of the livers and mesenteric lymph nodes (MLN) occurred within 24 h, with invasion of the liver increasing in a dose-dependent fashion (P < 0.01). If bile was prevented from reaching the intestine by bile duct ligation or cannulation, bacterial invasion of the liver and MLN was almost totally abrogated (P < 0.001). As i.v. challenge with LPS could induce the delivery of inflammatory mediators into the bile, biliary tumor necrosis factor alpha (TNF-alpha) concentrations were measured by bioassay. Biliary concentrations of TNF-alpha rose shortly after LPS challenge, peaked with a mean concentration of 27.0 ng/ml at around 1 h postchallenge, and returned to baseline levels (3.1 ng/ml) after 2.5 h. Although TNF-alpha cannot be directly implicated in the invasion process, we conclude that the invasiveness of the enteric pathogen S. enteritidis is enhanced by the presence of LPS in the blood and that this enhanced invasion is at least in part a consequence of the delivery of inflammatory mediators to the gastrointestinal tract by the hepatobiliary system.

DNA methylation and expression of p16(INK4A) gene in pulmonary adenocarcinoma and anthracosis in background lung

The p16 (CDKN2/MTS-1/INK4A) tumor-suppressor gene is frequently inactivated by DNA methylation in lung carcinomas. To clarify whether background anthracosis may play a role in DNA methylation and inactivation of the p16 gene, we examined DNA methylation of the p16-promoter region by methylation-specific polymerase chain reaction, and p16 expression immunohistochemically, and compared the results with the level of background anthracosis which was measured by an original quantitative method. At autopsy, DNA methylation of the p16 gene was observed in 6/19 tumors (32%) from patients who had died of pulmonary adenocarcinoma. The degree of background anthracosis (the effect of extrinsic carcinogenic factors) (mean absorbance value, A = 0.715) of the cases with p16-gene methylation was significantly higher than that without methylation (mean A value = 0.298). p16 expression was inactivated in all tumors with p16-gene methylation. The mean A value of black dust matter deposition in cases with normal expression of p16 (A = 0.151) was significantly lower than cases with abnormal expression of p16 (A = 0.531). These results indicate that the level of background anthracosis is closely associated with inactivation of p16 expression and also DNA methylation of the p16-gene promoter region in pulmonary adenocarcinogenesis. Int. J. Cancer (Pred. Oncol.) 84:609-613, 1999.

Cognitive behavioral therapy of minor depressive symptoms in elderly Chinese Americans: a pilot study

There is a high prevalence of suicide among elderly Chinese, and particularly among elderly Chinese women in Mainland China with a prevalence of 19.6 per hundred thousand. Since Chinese individuals may much more highly value education, a cognitive-behavioral package originated by Ricardo Munoz, Ph.D. was adapted for Chinese American subjects. The material was videotaped in eight sessions, approximately 25 minutes in length, to be shown to community subjects who were at least 40 years and over. In addition, a videotape of muscular relaxation techniques was made. A manual written in Chinese about the content of each class, was given to each subject when he/she attended. The experimental group showed significant improvement in the scores in the Hamilton Depression Scale, including the Somatic Subscale in the Hamilton Anxiety Scale. There was no significant improvement in the control group on any of the measures. Thus the study suggests the efficacy of psychoeducational classes in reducing symptoms of depression in non-patient community elderly. Other studies are being conducted among Korean Americans and Japanese Americans in the United States, and also in the Orient among Japanese elderly.

A novel spliced variant of the type 1 corticotropin-releasing hormone receptor with a deletion in the seventh transmembrane domain present in the human pregnant term myometrium and fetal membranes

CRH exerts its actions via activation of specific G protein-coupled receptors, which exist in two types, CRH-R1 and CRH-R2, and arise from different genes with multiple spliced variants. RT-PCR amplification of CRH receptor sequences from human myometrium and fetal membranes yielded cDNAs that encode a novel CRH-R type 1 spliced variant. This variant (CRH-R1d) is present in the human pregnant myometrium at term only, which suggests a physiologically important role at the end of human pregnancy and labor. The amino acid sequence of CRH-R1d is identical to the CRH-R1alpha receptor except that it contains an exon deletion resulting in the absence of 14 amino acids in the predicted seventh transmembrane domain. Binding studies in HEK-293 cells stably expressing the CRH-R1d or CRH-R1alpha receptors revealed that the deletion does not change the binding characteristics of the variant receptor. In contrast, studies on the G protein activation demonstrated that CRH-R1d is not well coupled to the four subtypes of G proteins (G(s), G(i), G(o), G(q)) that CRH-R1alpha can activate. These data suggest that although the deleted segment is not important for CRH binding, it plays a crucial role in CRH receptor signal transduction. Second messenger studies of the variant receptor showed that CRH and CRH-like peptides can stimulate the adenylate cyclase system, with reduced sensitivity and potency by 10-fold compared with the CRH-R1alpha. Furthermore, CRH failed to stimulate inositol trisphosphate production. Coexpression studies between the CRH-R1d or CRH-R1alpha showed that this receptor does not play a role as a dominant negative receptor for CRH.

Mutations of acidic residues in RAG1 define the active site of the V(D)J recombinase

The RAG1 and RAG2 proteins collaborate to initiate V(D)J recombination by binding recombination signal sequences (RSSs) and making a double-strand break between the RSS and adjacent coding DNA. Like the reactions of their biochemical cousins, the bacterial transposases and retroviral integrases, cleavage by the RAG proteins requires a divalent metal ion but does not involve a covalent protein/DNA intermediate. In the transposase/integrase family, a triplet of acidic residues, commonly called a DDE motif, is often found to coordinate the metal ion used for catalysis. We show here that mutations in each of three acidic residues in RAG1 result in mutant derivatives that can bind the RSS but whose ability to catalyze either of the two chemical steps of V(D)J cleavage (nicking and hairpin formation) is severely impaired. Because both chemical steps are affected by the same mutations, a single active site appears responsible for both reactions. Two independent lines of evidence demonstrate that at least two of these acidic residues are directly involved in coordinating a divalent metal ion: The substitution of Cys for Asp allows rescue of some catalytic function, whereas an alanine substitution is no longer subject to iron-induced hydroxyl radical cleavage. Our results support a model in which the RAG1 protein contains the active site of the V(D)J recombinase and are interpreted in light of predictions about the structure of RAG1.

Excitability of spinal cord and gracile nucleus neurons in rats with chronically injured sciatic nerve examined by c-fos expression

Low-threshold sensory pathways have been suggested to have an important role in the formation and maintenance of sensory abnormalities which are observed after peripheral nerve injury. Fos-like immunoreactive (Fos-LI) neurons are expressed in spinal cord laminae III-IV and the gracile nucleus by electrically stimulating the injured nerves at Abeta strength after sciatic nerve transection in rats. This suggests that the excitability of these neurons is increased by nerve injury. In this study, we investigated which receptors are involved in the regulation of the increased excitability in spinal and gracile nucleus neurons. The sciatic nerve of Sprague-Dawley rats (150 g) was transected 7 days before the experiment day. The rats were administered morphine, muscimol, baclofen, MK-801, CNQX, N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME) or clonidine i.p., and then electrically stimulated at 0.1 mA to the proximal region to the nerve injury site under urethane anesthesia. Two hours after the stimulation, Fos-LI expression was increased in the spinal cord dorsal horn and the gracile nucleus in control rats. Baclofen inhibited the Fos-LI expression both in the spinal cord and the gracile nucleus. Morphine inhibited only the Fos-LI expression in the posterior cutaneous (PC) nerve territory of laminae I-II, but not in the sciatic nerve (SC) territory, laminae III-IV nor the gracile nucleus. MK-801 had an inhibitory but complicated effect in laminae I-II and the gracile nucleus. The other drugs were not effective on Fos-LI expression. It is suggested that the GABA(B) receptor has a pivotal role in the regulation of Fos-LI expression after electrical stimulation to the injured low-threshold sensory fibers, and other receptors have little effect on the Fos-LI expression.

Purification, crystallization and preliminary crystallographic studies on the N-terminal fragment of human protein disulfide isomerase

A fragment of human protein disulfide isomerase composed of the thioredoxin-like a and b domains (ab) has been expressed in Escherichia coli as a fusion protein with glutathione-S-transferase and purified after thrombin cleavage. Two forms of ab crystal were obtained with polyethylene glycol as precipitant and different additives at pH 7.5. The space group of form I is P4(1)2(1)2 or P4(3)2(1)2, with unit-cell dimensions a = 81.5, c = 259.7 A. The space group of form II is P4(1)22 or P4(3)22, with unit-cell dimensions a = 82.7, c = 86.5 A.

Androgenic maintenance of the erectile response in the rat

Ongoing studies in this laboratory have used the castrated rat, with and without testosterone replacement, to investigate how androgens maintain the erectile response. The high intracavernosal pressures during erection depend on both an increase in the rate at which blood flows into the sinuses of the corpus cavernosum and a decrease in the rate at which blood flows out (veno-occlusion). Accordingly, our studies investigated androgenic regulation of the arterioles that regulate inflow and of the intracavernosal muscle that regulates the veno-occlusive mechanism controlling outflow. The results of these studies show that castration causes a decline in the rate of inflow and that androgen replacement reverses this decline. The decline in inflow in the castrated rats is also reversed by the administration of a nitric oxide donor drug, suggesting that the androgen may regulate inflow by increasing the synthesis of nitric oxide. Testosterone also appears to regulate outflow by controlling the sensitivity of the erectile mechanisms to norepinephrine, considered to be the principle vaso-constrictor neurotransmitter in the erectile response. Taken together, the results of these studies suggest that androgens control the erectile response by altering the synthesis and action of the neurotransmitters that normally alter the state of contraction and relaxation of smooth muscle in the erectile tissue.

Development and application of a minimal-adenoviral vector system for gene therapy of hemophilia A

To achieve efficient delivery and sustained expression of the human factor VIII cDNA in vivo, a minimal-adenoviral (mini-Ad) vector system was developed. The system is composed of a mini-Ad vector with essential cis-elements (less than 1 kb) of the viral genome, an E1-deleted ancillary Ad with packaging attenuation, and an E1-complementing production cell line. Based on this system, MiniAdFVIII was generated to deliver a 27 kb expression cassette consisting of a full-length human factor VIII cDNA flanked by human albumin promoter and genomic sequences. The MiniAdFVIII vector mediated expression of functional human factor VIII in HepG2 and 293 cells. A single-dose intravenous injection of 10(11) viral particles in hemophilic mice of MiniAdFVIII produced a sustained high-level expression of human factor VIII (at 100-800 ng/ml up to 369 days) which corrected the FVIII-deficient phenotype. Safety studies of MiniAdFVIII showed that there were no significant toxic effects in mice and dogs after single intravessel doses of up to 3 x 10(11) and 6 x 10(12) viral particles, respectively. Studies for developing the MiniAdFVIII vector with a site-specific integration mechanism and progress in the development of a human factor VIII-tolerized mouse model for pre-clinical studies of MiniAdFVIII are reported. Further pre-clinical studies and product development of MiniAdFVIII for clinical trials are also discussed.

[Determination of resveratrol in grape wine by high performance liquid chromatography]

Resveratrol is a microactive factor for preventing human cancer. A reversed phase high performance liquid chromatographic method for the determination of resveratrol in grape wine was developed. Samples were extrated by ethyl acetate and washed with 3% NaHCO3; after dehydrated with Na2SO4 and dried in vacunm at 40 degrees C, dissovled in acetonitrile. The conditions of HPLC analysis were as follows: the maximum absorptions of trans-resveratrol and cis-resveratrol were at 306 nm and 280 nm respectively. Separation was achieved by the use of mu-Bondapak C18 column (3.9 mm x 300 mm). The mobile phase was V(acetonitrile):V(water) = 40:60. The retention times of trans- and cis-resveratrol were 7.7 min and 8.9 min respectively. The recovery rates were 90.0%-97.8% and the CV was 3.3%. Detection limit was 10 micrograms/L. Eleven kinds of red and white grape wine made in China were detected. All of them contained resveratrol, but the quantity, from 10.0 to 920.0 micrograms/L, were quite different.

Enhancing or suppressive effects of antibodies on processing of a pathogenic T cell epitope in thyroglobulin

Thyroglobulin (Tg)-specific Abs occur commonly in thyroid disease, but it is not clear to what extent they affect Tg processing and presentation to T cells. Here we show that generation of the nondominant pathogenic Tg epitope (2549-2560), containing thyroxine (T4) at position 2553 (T4(2553)), is augmented by Tg-specific IgG mAbs that facilitate FcR-mediated internalization of Tg. However, other mAbs of the same (IgG1) subclass enhanced Tg uptake by APC but had no effect on the generation of this peptide. Treatment of APC with chloroquine or glutaraldehyde abrogated enhanced generation of T4(2553). The boosting effect was selective, since the enhancing mAbs did not facilitate generation of the neighboring cryptic (2495-2511) peptide, which is also pathogenic in mice. When Tg was simultaneously complexed to a mAb reactive with T4(2553) and to a mixture of boosting mAbs, the presentation of this epitope was totally suppressed. These results suggest that Tg-specific Abs alter Tg processing and may boost or suppress the presentation of nondominant pathogenic determinants during the course of disease.

Effects of "products of chicken embryo" on growth and sexual development in rats

Products of Chicken Embryo (PCE) such as Ji-Pei-Jing is a kind of food for Chinese children prepared from chicken embryo. Female rats on 21 days were administered with aqueous solutions of Ji-Pei-Jing (1.2%, 3%, 12%, and 48%, respectively) by gavage up to their onsets of puberty. The rats in the control group were treated with distilled water. However, Ji-Pei-Jing treatment exerted some effects on sexual maturation in the immature female rats. Essentially, the effects showed a dose-response tendency with an inverted "U" shape. The age of vaginal opening for group treated with Ji-Pei-Jing was significantly earlier than that to the control. Its uterus weight/b.w. ratio also significantly increased on day 30 and at the first estrus. There were significantly increases in the adrenal weight/b.w. ratio of 30-day-old rats that were treated with 3%, 12%, and 48% Ji-Pei-Jing. The rats treated with 48% Ji-Pei-Jing had significantly lesser ovary weight/b.w. ratio on day 30, too. The rats treated with Ji-Pei-Jing could normally ovulate at the first estrus, and no significant differences were observed during estrous cycles. The effects of PCE on serum levels of E2, P, LH in 30-day-old rats and FSH in 28-day-old rats were elevated significantly by 3% Ji-Pei-Jing treatment. It appears that the effects of PCE result from interaction of contained complex physiologically active substances. Steroids, especially estradio-17 beta, possibly play a key role, and polypeptide hormones may also exert important effects.

[Plasminogen activator inhibitor-1 mRNA expression by the iris and lens epithelial cells of rabbit eye with intraocular lens implantation]

OBJECTIVE

To investigate the change of plasminogen activator inhibitor-1 (PAI-1) synthesized by the iris and the lens epithelial cells (LECs) after extracapsular cataract extraction (ECCE) with intraocular lens (IOL) implantation and the role of PAI-1 in the occurrence of fibrin reaction and the formation of posterior capsular opacification.

METHODS

Eight adult rabbits were studied. In each rabbit, one eye underwent ECCE with IOL implantation and the other eye was normal without any surgical intervention. The iris tissue and the lens capsule of each two normal eyes and each two surgical eyes were excised on the postoperative 1, 7, 15 and 30 days respectively. The amount of PAI-1 mRNA expression in the specimens was detected by using reverse transcription-polymerase chain reaction (RT-PCR). The data were analyzed statistically.

RESULTS

The amount of PAI-1 mRNA expresson in the iris tissue and the LECs of the surgical eyes displayed a significant increase on the first day after operation. The high expression of PAI-1 mRNA by the iris might last 15 days (P < 0.001), but it declined to the normal range on the postoperative 30 days (P = 0.87). The high level of PAI-1 mRNA expresson by the LECs in the surgical eyes had significant difference when compared with that of the normal eyes at 1, 7, 15 and 30 days postoperatively (P < 0.001).

CONCLUSION

It is indicated that PAI-1 enzyme is a major cause for fibrin reaction after ECCE with IOL implantation, and may play critical roles in the development of posterior capsular opacification.

Aldosterone biosynthesis in extraadrenal tissues

OBJECTIVE

To determine whether extraadrenal tissues synthesize aldosterone in addition to vascular tissue and brain.

METHODS

Ex vivo kidney perfusion was performed in normal Wistar rats, ACEI pretreated and adrenalectomized rats prior to the perfusion experiment. After equilibration for 30 minutes, 120 ml of perfusate was collected and subjected to reverse-phase HPLC and then aldosterone was measured by RIA. By RT-PCR and Southern blot the expression of aldosterone synthase gene-CYP11B2 mRNA was studied in both kidney tissue and cultured renal tubular epithelial cell, lung and liver tissues. In situ hybridization was used to identify the cell types of liver and lung expressing CYP11B2 mRNA.

RESULTS

Production of aldosterone in the kidney perfusate was not changed in adrenalectomized rats although it was decreased in the group pretreated with ACEI perindopril. By RT-PCR and Southern blot the expression of CYP11B2 mRNA was demonstrated in both kidney tissue and cultured renal tubular epithelial cell. We have also identified CYP11B2 mRNA expression in liver and lung of rats. In situ hybridization showed that CYP11B2 mRNA was localized in the endoplasm of liver fat-storing cell (Ito cells) and type II alveolar cells of lung.

CONCLUSIONS

These studies prove that kidney, liver and lung are able to produce aldosterone.

Ablation of renal tumors in a rabbit model with interstitial saline-augmented radiofrequency energy: preliminary report of a new technology

OBJECTIVES

To evaluate the efficacy of interstitial saline radiofrequency energy for reproducibly ablating nonmalignant (control) and malignant (the VX-2 tumor) renal tissue in a rabbit model, and to determine the ability of conventional gray-scale and power sonography to image the tumor and ablative process in real time before, during, and after treatment.

METHODS

The VX-2 tumor was implanted beneath the renal capsule in 18 rabbit kidneys. Twelve days after implantation, 50 W of 500-kHz radiofrequency energy was delivered into the surgically externalized renal tumor and contralateral control kidney for 30 or 45-second treatment intervals using an interstitial saline-augmented radiofrequency probe (the virtual electrode). Localization of the tumor and response to treatment were imaged with gray-scale and power Doppler ultrasonography. The effect of radiofrequency and extent of the destructive process on benign and malignant renal tissue were evaluated histologically.

RESULTS

Mean tumor size was 1.3 x 0.7 cm. Both 30 and 45-second treatment intervals provided marked tissue/tumor ablation. Gross anatomic and histologic analysis showed time-dependent ablated lesions averaging 1.4+/-0.3 x 1.0+/-0.3 cm (30-second treatment) and 1.8+/-0.4 x 1.5+/-0.3 cm (45-second treatment), with clear demarcation of the surrounding parenchyma. Conventional gray-scale sonography allowed visualization of the ablative process, and power Doppler ultrasound demonstrated changes in the vascular pattern of the tumor both before and after ablation. No immediate treatment-related complications were observed.

CONCLUSIONS

These preliminary studies in a rabbit model demonstrate the feasibility of using the interstitial saline-augmented electrode to ablate small renal tumors and the ability to simultaneously visualize the ablative process using real-time ultrasonography. This technology may have the potential to treat small renal tumors in a minimally invasive manner in the clinical setting.

[Bio-safety testing for retroviral vector as gene therapy delivery system]

OBJECTIVE

To generate a bio-safety testing system including the testing of sterility, mycoplasma and replication-competent retroviruses(RCR) in the study of gene therapy anti-hepatitis B virus by intracellular immunization.

METHODS

Mycoplasma was detected by polymerase chain reaction. S+/L- assay, NIH3T3 amplification and rescue assay of neo gene were performed to determine RCR.

RESULTS

The results showed that all of the packaging cell lines were negative for aerobic, anaerobic bacteria and fungi. One of the packaging cell lines was positive for mycoplasma. No RCR was detected in all of the packaging cell lines.

CONCLUSIONS

The results suggested that the methods using in present report are stable and sensitive, it is very useful for bio-safety testing of gene therapy in clinical trials.

[Study on effect and mechanism of essential garlic oil in inhibiting monocyte-vascular endothelial cell adhesion induced by interleukin-1 alpha]

OBJECTIVE

To observe the effects of essential garlic oil (EGO) on vascular cell adhesive molecule-1 (VCAM-1) expression of endothelial cell and monocyte adhesion induced by interleukin-1 alpha (IL-1 alpha).

METHODS

Human umbilical vein endothelial cells (HUVEC) were isolated by pancreatin digestion method and co-cultured with U937 monocyte and IL-1 alpha or EGO + IL-1 alpha respectively. The adhesion rate of monocyte to endothelial cell was measured and mean fluorescent intensity of immuno-stained of VCAM-1 was determined by ACAS 570.

RESULTS

EGO showed significant inhibition on VCAM-1 expression induced by IL-1 alpha either in simple culture with HUVEC or in co-culture with HUVEC + U937, and could obviously down regulate the monocyte-endothelial cell adhesion under effect of IL-1 alpha.

CONCLUSION

EGO has the effect of antagonizing against adhesion of monocyte and vascular endothelial cell, it may be due to the inhibition of EGO on adhesive molecular expression on endothelial cell.

Two-layer sample preparation: a method for MALDI-MS analysis of complex peptide and protein mixtures

The analytical performance of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for direct analysis of peptide and protein mixtures is strongly dependent on the sample and matrix preparation. A two-layer sample preparation method is demonstrated to be very effective for analyzing complex mixtures. In this method, the first layer on the MALDI probe is the densely packed matrix microcrystals formed by fast solvent evaporation of a matrix solution. A mixture solution containing both matrix and sample is then deposited onto the first layer to form uniform analyte/matrix micrococrystals. It is found that the addition of matrix to the second-layer sample solution proves to be critical in analyzing mixtures of peptides and proteins covering a broad mass range. The effect of solvent conditions for preparing the second-layer solution is discussed. The application of this method is demonstrated for the analysis of cow's milk where milk proteins as well as peptide fragments produced from proteins by indigenous proteinases are detected. Direct analyses of peptides and proteins from a bacteria extract and crude egg white are also illustrated.

p53- and ATM-dependent apoptosis induced by telomeres lacking TRF2

Although broken chromosomes can induce apoptosis, natural chromosome ends (telomeres) do not trigger this response. It is shown that this suppression of apoptosis involves the telomeric-repeat binding factor 2 (TRF2). Inhibition of TRF2 resulted in apoptosis in a subset of mammalian cell types. The response was mediated by p53 and the ATM (ataxia telangiectasia mutated) kinase, consistent with activation of a DNA damage checkpoint. Apoptosis was not due to rupture of dicentric chromosomes formed by end-to-end fusion, indicating that telomeres lacking TRF2 directly signal apoptosis, possibly because they resemble damaged DNA. Thus, in some cells, telomere shortening may signal cell death rather than senescence.

[HBxAg enhanced p53 protein accumulation in hepatoma cells]

OBJECTIVE

In order to determine the interaction between HBxAg and p53 protein and its role in hepatocarcinogenesis.

METHODS

Cotransfection was performed using reporter gene, chloramphenical acetyltransferase (CAT), p53 and HBVx gene, and dexamethasone inducible HBx plasmid pMAMHBx was constructed for the experiment. Human hepatoma cell line Hep3B was used as the target cell. The activity of HBxAg and p53 was detected by CAT assay and immunohistochemical staining after transient transfection.

RESULTS

HBxAg could increase the accumulation of p53 protein in cells and enhance CAT expression. Immunohistochemical staining showed that p53 protein bound to HBxAg in the cytoplasm and formed a complex causing a partial block of the process of p53 during passing through the nuclear membrane from the cytoplasm.

CONCLUSION

Data strongly suggested that HBxAg is capable of binding p53 and forms a protein-protein complex which might reduce or inactivate p53's antiproliferative activity and plays an important role in the pathogenesis of HBV-associated hepatocellular carcinoma.

Association and linkage analysis of candidate chromosomal regions in multiple sclerosis: indication of disease genes in 12q23 and 7ptr-15

Four recent genome-wide screen studies in multiple sclerosis (MS) identified a number of candidate regions for susceptibility genes in addition to the HLA complex in 6p21. However, none of these regions provided formally significant evidence for genome-wide linkage. We have investigated such regions in 46 Swedish multiplex MS families, 28 singleton families, 190 sporadic MS patients and 148 normal controls by parametric and nonparametric linkage and association analysis. One microsatellite marker, in 12q23, provided evidence for association in addition to suggestive transmission distortion and slightly positive linkage. In addition, a marker in 7ptr-15 showed a significant transmission distortion as well as a highly significant score in affected pedigree member analysis, but not quite significant deviations in association analysis. One of three markers in 5p, a region implicated in all four previous studies, showed a weakly positive lod score, but no other evidence of importance. Markers in 2p23, 5q11-13, 6q25, 7q21-22, 11q21-23, 13q33-34, 16p13.2, 18p11.32-23, Xp21.3 provided little or no evidence of importance for MS. In summary, these data support the importance of genome-wide screens in the identification of new candidate loci in polygenic disorders.

A role for the hepatobiliary system in IgE-mediated intestinal inflammation in the rat

BACKGROUND

For many years the central focus of research into gastrointestinal hypersensitivity reactions has been the mast cell population of the intestinal lamina propria. Since bile is known to deliver immunological mediators to the gastrointestinal tract, the possibility arises that extra-intestinal populations of mast cells may also contribute to IgE-mediated intestinal damage.

OBJECTIVES

To characterize hepatic mast cells in the rat and to investigate the role of the hepatobiliary system in a model of IgE-mediated reactivity to dietary antigen.

METHODS

Wistar rats were passively sensitized with monoclonal antidinitrophenyl (DNP) IgE antibodies, and were later challenged orogastrically with DNP-HSA. Additional animals were sensitized, then bile duct-cannulated prior to antigen challenge. At various time points, liver and intestinal samples were collected for histological examination, and bile was collected and assayed for histamine and TNFalpha.

RESULTS

Hepatic mast cells display a mucosal mast cell-like phenotype, and are closely associated with the vessels of the portal triads. Orogastric antigen challenge led to a rapid and significant decline (P<0.0001) in detectable mast cells as a result of anaphylactic degranulation. The median number of granulated mast cells associated with each portal triad in liver sections declined from six per portal triad to one per portal triad post-antigen challenge. After 15 min, biliary histamine concentrations rose above background levels (P<0.01). TNFalpha was also detectable in the majority (4/6) of bile samples within 15 min of challenge. Histological examination of the gastrointestinal mucosa revealed disruption to the villous epithelium ranging from oedematous changes to gross destruction. Such damage was not seen in animals in which bile had been externally drained.

CONCLUSION

The data indicate that biliary products are major contributors to the gastrointestinal damage arising from IgE-mediated hypersensitivity reactions in the rat, and such hypersensitivity reactions may involve a population of mast cells which reside in the liver.

[Mechanism of injury by active oxygen radical to hemoglobin]

The injury effects of O2-. and H2O2 on the hemoglobin were investigated. The results showed that the metal prosthetic group was injured by O2-. and H2O2, but the mechanism of O2-. and H2O2 effects was different. Through the charge neutralization O2-. destroying the static electrical interactions between prosthethic groups and amino acid residues, it thereby caused prosthetic group dropped. H2O2 had Fenton reaction with Fe2+ in prosthetic group, hence produced .OH. It can destroy the porphyrin structure at fixed point in short distance, so the prosthetic group was destroyed and non-reversible.

[Application of molecular epidemiology in the study of occupational chemical carcinogenesis]

This paper described the concept of moleculalr epidemiology, it's differences from traditional epidemiology and what the author learned from conducting molecular epidemiology recently. 1. Molecular epidemiology is the borderline subject in combination of molecular biology with epidemiology. 2. The level of chemical carcinogen formed in vivo and the amount of combination of chemical carcinogen either in the level from vivo or in biologic effective dose of combination of chemical carcinogen with macromolecular are all related to cancer development. 3. The syndrome of chromosome aberration is an early biologic effect in cancer process and oncogen activation or suppressing gene inactivation might be necessary for malignant transformation from initiated cell. 4. Individual susceptibility could be affected by host and acquired factors. 5. Biologic bank could provide continuous observation and comparision between before and after cancer formation.

Linkage between melanocytic tumor development and early burst of Ret protein expression for tolerance induction in metallothionein-I/ret transgenic mouse lines

We examined the basis of the all or none difference in inducing melanocytic tumor development among three transgenic mouse lines (304, 192 and 242) to which the same promoter-enhancer (metallothionein-I) and oncogene (ret) were introduced. We initially demonstrated that both skin melanosis and Ret protein expression in skin, thymus and brain first became detectable before or immediately after birth in the mice of the tumor developing lines (304 and 192), whereas they became detectable a few days after birth in the mice of the non-tumor developing line (242) by Western blotting and immunohistochemical analysis. Interestingly, the Ret protein expression in skin developed rapidly after birth as a burst with peak levels on 0.5-1.5 day newborns of lines 304 and 192 and on 7.0-7.5 day-old mice of line 242. The levels of autophosphorylation of Ret kinase in skin were, however, invariable among these three transgenic mouse lines. The mice of line 242, but not those of lines 192 and 304, responded to Ret protein immunization by increased antigen-dependent lymphocyte proliferation and T-cell-mediated tumor growth suppression in vitro. Furthermore, ret-transgenic mice of line 242, but not line 304, rejected the subcutaneously transplanted tumors that had originally developed in a mouse of line 304. These results suggest that whether oncogene product-specific-tolerance is established or not to antitumor immunity may be decided by the dynamics of ret oncogene expression before and after delivery and this is the primary factor determining development or non-development of melanoma.

One protein, two enzymes

Two enzymes, designated, E-2 and E-2', catalyze different oxidation reactions of an aci-reductone intermediate in the methionine salvage pathway. E-2 and E-2', overproduced in Escherichia coli from the same gene, have the same protein component. E-2 and E-2' are separable on an anion exchange column or a hydrophobic column. Their distinct catalytic and chromatographic properties result from binding different metals. The apo-enzyme, obtained after metal is removed from either enzyme, is catalytically inactive. Addition of Ni2+ or Co2+ to the apo-protein yields E-2 activity. E-2' activity is obtained when Fe2+ is added. Production in intact E. coli of E-2 and E-2' depends on the availability of the corresponding metals. These observations suggest that the metal component dictates reaction specificity.

Detection and identification of low-mass peptides and proteins from solvent suspensions of Escherichia coli by high performance liquid chromatography fractionation and matrix-assisted laser desorption/ionization mass spectrometry

The application of high performance liquid chromatography (HPLC) to separate components in solvent suspension of Escherichia coli followed by off-line matrix-assisted laser desorption/ionization (MALDI) analysis of collected fractions results in the detection of over 300 peaks in the 2000-19,000 Da mass range, an order of magnitude increase in the number of components observed when compared with direct MALDI analysis of the entire solvent suspension. Mass measurements of these separated components using a time-lag focusing MALDI instrument are reported. MALDI analysis of the proteolytic digests of several collected fractions facilitates the identification of three components as specific proteins expected to be present in E. coli. The methodologies reported here should be very useful in searching for unique biomarkers for bacterial discrimination.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for polymer analysis: solvent effect in sample preparation

The success of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry for the characterization of polymer structures and for the determination of average molecular weights and distributions depends on the use of a proper sample/matrix preparation protocol. This work examines the effect of solvents, particularly solvent mixtures, used to prepare polymer, matrix, and cationization reagent solutions, on MALDI analysis. It is shown that the use of solvent mixtures consisting of polymer solvent does not have a significant effect on the molecular weight determination of polystyrene 7000 and poly(methyl methacrylate) 3750. However, solvent mixtures containing a polymer nonsolvent can affect the signal reproducibility and cause errors in average weight measurement. This solvent effect was further investigated by using confocal laser fluorescence microscopy in conjunction with the use of a fluorescein-labeled polystyrene. It is demonstrated that sample morphology and polymer distribution on the probe can be greatly influenced by the type of solvents used. For sample preparation in MALDI analysis of polymers, it is important to select a solvent system that will allow matrix crystallization to take place prior to polymer precipitation. The use of an excess amount of any polymer nonsolvent should be avoided.