Use of capillary electrophoresis with UV detection as a screening method to determine histamine in fish samples

Histamine levels in fish, extracted with methanol, were determined by capillary electrophoresis (CE) using phosphate buffer pH 2.5 and U.V. detection at 210 nm. Histamine was well separated from the other co-extracted components under the given CE condition without any cleanup of the methanol extract. The average recovery of spiked histamine in various types of fish samples was 96%. Using the same methanol extracts from various fish samples, we then compared histamine concentration obtained by CE and fluorometric methods.

APOBEC-2, a cardiac- and skeletal muscle-specific member of the cytidine deaminase supergene family

APOBEC-1, which mediates the editing of apolipoprotein (apo) B mRNA, is the only known member of the C (cytidine)-->U (uridine) editing enzyme subfamily of the cytidine deaminase supergene family. Here we report the cloning of APOBEC-2, another member of the subfamily. Human and mouse APOBEC-2 both contain 224 amino acid residues, and their genes are mapped to syntenic regions of human chromosome 6 (6p21) and mouse chromosome 17. By phylogenetic analysis, APOBEC-2 is shown to be evolutionarily related to APOBEC-1, and analysis of substitution rates indicates that APOBEC-2 is a much better conserved gene than APOBEC-1. APOBEC-2 mRNA and protein are expressed exclusively in heart and skeletal muscle. APOBEC-2 does not display detectable apoB mRNA editing activity. Like other editing enzymes of the cytidine deaminase superfamily, APOBEC-2 has low, but definite, intrinsic cytidine deaminase activity. The identification of APOBEC-2 indicates that APOBEC-1 is not the only member of the C-->U editing enzyme subfamily, which, like the A (adenosine)-->I (inosine) subfamily of editing enzymes, must encompass at least two and possibly more different deaminase enzymes. It suggests that the C-->U editing affecting apoB mRNA and other RNAs is not an isolated event mediated by a single enzyme but involves multiple related proteins that have evolved from a primordial gene closely related to the housekeeping enzyme cytidine deaminase.

Roles of the three major phosphorylation sites of hepatitis B virus core protein in viral replication

Hepatitis B virus (HBV) core protein is a phosphoprotein. Its three major phosphorylation sites have been identified at the serine residues located at amino acids 157, 164, and 172. In order to investigate the role of core protein phosphorylation in HBV replication, these three serine residues were mutated to alanine to mimic nonphosphorylated serine or to glutamic acid to mimic phosphoserine. The nonphosphorylated core protein analog did not package the HBV pregenomic RNA, and the phosphorylated analog packaged the pregenomic RNA but failed to support viral DNA replication. These results indicate that the core protein phosphorylation may be important for pregenomic RNA packaging and that its dephosphorylation may be important for viral DNA replication. The individual roles of these three major phosphorylation sites in HBV replication were further investigated by being mutated to alanine in different combinations. The results showed that the serine residue at amino acid 157 was not essential for pregenomic RNA packaging, whereas the serine residues at amino acids 164 and 172 were more important. Furthermore, the serine residue at amino acid 157 was not essential for viral DNA replication or viral maturation.

Genetic deficiency of acylation stimulating protein (ASP(C3ades-Arg)) does not cause hyperapobetalipoproteinemia in mice

The acylation stimulating protein (ASP) is a 76-amino acid peptide that has been proposed as a potent mediator of triglyceride synthesis and, when functionally impaired, as a major cause of hyperapobetalipoproteinemia (HyperapoB). Purification and sequence analysis of ASP from human sera have revealed that ASP is identical to the complement C3-derived activation peptide C3ades-Arg. Because C3 is the precursor for C3ades-Arg and therefore ASP, a deficiency in C3 would be predicted to result in a phenotype characteristic of HyperapoB. To test this hypothesis in vivo, the current study was undertaken in which ASP(C3ades-Arg)-deficient mice were used as a model system. No significant differences were found in the triglyceride, cholesterol, or free fatty acid concentrations in the plasma of fasted normal and ASP(C3ades-Arg)-deficient animals. In addition, plasma lipoprotein analyses indicated that the very low density lipoprotein, low density lipoprotein, and high density lipoprotein cholesterol and triglyceride concentrations as well as the apolipoprotein B-48 and B-100 levels were not significantly different in the plasma of ASP(C3ades-Arg)-deficient and wild type mice. Furthermore, when challenged with an oral fat load, the ASP(C3ades-Arg)-deficient mice showed no impaired ability to clear triglycerides and free fatty acids from their circulation when compared with their wild-type littermates. Collectively, these results indicate that ASP(C3ades-Arg) deficiency does not cause HyperapoB in mice and that the physiological importance of impaired ASP(C3ades-Arg) function as a cause of hyperapobetalipoproteinemia needs to be reevaluated.

Endogenous histamine reduces plasma insulin-like growth factor I via H1 receptor-mediated pathway in the rat

Endotoxin has been recently shown to reduce plasma insulin-like growth factor I. As it was reported that histamine can induce gut-derived endotoxemia, we wanted to determine whether histamine has a similar effect on plasma insulin-like growth factor I. Compound 48/80 (a histamine releaser) was injected subcutaneously into rats, then blood was taken for plasma insulin-like growth factor I assay and the livers were assayed for insulin-like growth factor I mRNA. Like endotoxin, injection of compound 48/80 significantly reduced plasma insulin-like growth factor I. Six hours post-injection, plasma insulin-like growth factor I was reduced by 61% (P < 0.001), and 24 h post-injection, it was still lower (by 35% P < 0.001) than in the control group. Hepatic insulin-like growth factor I mRNA was not reduced by this treatment. The effect of compound 48/80 on plasma insulin-like growth factor I was significantly attenuated by oral administration of the histamine H1 receptor antagonist (chlorpheniramine), but not by the histamine H2 receptor antagonists (cimetidine and ranitidine). Oral administration of polymyxin B (an antiendotoxin antibiotic) did not attenuate the effect of compound 48/80 on plasma insulin-like growth factor I at all. In conclusion, endogenous histamine reduces plasma insulin-like growth factor I via H1 receptor-mediated pathway. Our study suggests a novel role of histamine in the regulation of insulin-like growth factor I metabolism in vivo.

Adenovirus-mediated overexpression of microsomal triglyceride transfer protein (MTP): mechanistic studies on the role of MTP in apolipoprotein B-100 biogenesis

The intracellular concentration of the microsomal triglyceride transfer protein large subunit (lMTP), the abetalipoproteinemia gene product, is tightly controlled. To date, attempts at overexpressinglMTP in vivo or in vitro have been unsuccessful. We successfully overexpressed lMTP in HepG2 cells using an adenoviral vector containing an lMTP cDNA, AdMTP. AdMTP-transduced HepG2 cells overexpressed MTP activity. They secreted increased amounts of apoB-100 lipoproteins with LDL and HDL density into the medium. lMTP overexpression alone minimally changed the density profile of apoB-containing lipoproteins, but addition of oleic acid shifted the profile toward lower densities. Oleic acid had a greater stimulatory effect on apoB-100 secretion in control HepG2 cells than in AdMTP-transduced cells, because (i) adenoviral transduction per se suppressed protein synthesis, affecting apoB-100 and albumin equally, and (ii) adenoviral transduction partially attenuated the increase in triglyceride synthesis in response to oleic acid supplementation. AdMTP treatment greatly diminished the intracellular degradation of apoB-100, but in comparison with recombinant virus containing luciferase cDNA (AdLuc), it caused no change in its biosynthetic rate. It greatly reduced, but did not eliminate, its proteasomal degradation. Our study constitutes the initial demonstration that adenovirus-mediated transfer of lMTP markedly stimulates MTP expression which in turn stimulates apoB-100 production. The mechanism involves a downregulation of ubiquitin-proteasome-mediated degradation without any change in synthetic rate.

Fosinopril and hydrochlorothiazide combination versus individual components: lack of a pharmacokinetic interaction

OBJECTIVE

To evaluate the pharmacokinetic interaction and bioequivalence of a combination formulation of the angiotensin-converting enzyme inhibitor fosinopril and the diuretic hydrochlorothiazide (HCTZ).

METHODS

In an open-label, balanced, randomized incomplete block, three-way crossover fashion, healthy men received single doses of three of four regimens in one of two independent studies. Regimens for study A (36 subjects): (1) fosinopril 10-mg tablet, (2) HCTZ 12.5-mg tablet, (3) a combination tablet of fosinopril 10 mg plus HCTZ 12.5 mg, or (4) coadministered tablets of fosinopril 10 mg and HCTZ 12.5 mg. Study B (40 subjects) received: (1) fosinopril 20-mg tablet, (2) HCTZ 12.5-mg tablet, (3) a combination tablet of fosinopril 20 mg plus HCTZ 12.5 mg, or (4) coadministered tablets of fosinopril 20 mg and HCTZ 12.5 mg.

RESULTS

There was no evidence of any significant effect of HCTZ on the pharmacokinetics of fosinoprilat, based on maximum concentration value, AUC, or cumulative urinary recovery over 24 hours. Fosinoprilat had no clinically important effect on the pharmacokinetics of HCTZ only slightly decreasing its AUC by 14% in study A. Coadministration was well tolerated; no new adverse events were reported with the combination tablet.

CONCLUSIONS

Fosinopril and HCTZ in a combination tablet display pharmacokinetic profiles similar to those achieved when either drug is administered alone or when coadministered in separate tablets. When used with HCTZ, the favorable pharmacokinetic feature of fosinopril, dual and compensatory pathways of renal and hepatic elimination, is preserved.

A comparison among four regimens of itraconazole treatment in onychomycosis

The purpose of this study was to compare the efficacy of different dosage regimens in the management of onychomycosis with itraconazole and to determine the results of a further 1-week intermittent pulse treatment in non-cured patients. In this study, 153 patients were randomly allocated to four groups. Patients in group A were treated with daily doses of 100 mg for 3 months in the case of fingernail onychomycosis and for 4 months in the case of toenail onychomycosis. Patients in the other groups received a intermittent pulse therapy, in which the drug was taken for 1 week, then discontinued for 3 weeks, three cycles for fingernail and four cycles for toenail infection. The daily doses were 400 mg (group B), 300 mg (group C) and 200 mg (group D). After therapy, non-cured patients were treated further with one cycle in which the daily dose was 400 mg. Patients were subsequently observed for 9 months and efficacy was assessed by mycological examination and the growth of unaffected nails. At the end of the therapy, the cure rates in the four groups were 19.1% (A), 15.2% (B), 18.9% (C) and 17.9% (D), and no significant differences were found between each of B, C, D and A. At the end of the study, the cure rates were 76.2%, 91.3%, 78.4%, 28.6% respectively. The group that received further treatment had a cure rate of 55.6% at the end of the first month and of 83.3% in the second month. Drug tolerability was equally good in the four groups. Intermittent pulse therapy with a daily dose of 400 mg had the highest cure rate. Treatment of improved but non-cured patients with a dose of 400 mg intermittent pulse therapy markedly increased the cure rate. All treatment regimens were well tolerated.

Liver-specific inactivation of the abetalipoproteinemia gene completely abrogates very low density lipoprotein/low density lipoprotein production in a viable conditional knockout mouse

Conventional knockout of the microsomal triglyceride transfer protein large subunit (lMTP) gene is embryonic lethal in the homozygous state in mice. We have produced a conditional lMTP knockout mouse by inserting loxP sequences flanking exons 5 and 6 by gene targeting. Homozygous floxed mice were born live with normal plasma lipids. Intravenous injection of an adenovirus harboring Cre recombinase (AdCre1) produced deletion of exons 5 and 6 and disappearance of lMTP mRNA and immunoreactive protein in a liver-specific manner. There was also disappearance of plasma apolipoprotein (apo) B-100 and marked reduction in apoB-48 levels. Wild-type mice showed no response, and heterozygous mice, an intermediate response, to AdCre1. Wild-type mice doubled their plasma cholesterol level following a high cholesterol diet. This hypercholesterolemia was abolished in AdCre1-treated lMTP-/- mice, the result of a complete absence of very low/intermediate/low density lipoproteins and a slight reduction in high density lipoprotein. Heterozygous mice showed an intermediate lipoprotein phenotype. The rate of accumulation of plasma triglyceride following Triton WR1339 treatment in lMTP-/- mice was <10% that in wild-type animals, indicating a failure of triglyceride-rich lipoprotein production. Pulse-chase experiments using hepatocytes isolated from wild-type and lMTP-/- mice revealed a failure of apoB secretion in lMTP-/- animals. Therefore, the liver-specific inactivation of the lMTP gene completely abrogates apoB-100 and very low/intermediate/low density lipoprotein production. These conditional knockout mice are a useful in vivo model for studying the role of MTP in apoB biosynthesis and the biogenesis of apoB-containing lipoproteins.

[Separation and detection of tryptophan metabolites in biological samples]

A reversed phase HPLC method for separation and determination of the major tryptophan (TRP) metabolites in both pyrrolas pathway and TRP hydroxylase pathway, including TRP, kynurenine(KN), 3-hydroxykynurenine(3-HKN), kynurenic acid(KA), xanthurenic acid(XA), 5-hydroxytryptophan(5-HTP), 5-hydroxytryptamin(5-HT) and 5-hydroxyindoleacetic acid(5-HIAA), has been developed by sequential optimization of mobile phase based on acetate buffer and methanol. Trichloroacetic acid(TCA) was used as ion-pairing reagent to increase the retention of 3-HKN. The effects of pH and concentrations of TCA on separation were studied. Good separation can be achieved at pH 4.0-5.0 of mobile phase in less than 25 min. When TCA was not used, 3-HKN was hard to be detected in biological samples. The maximum retention of 3-HKN was obtained at pH 4.0 with mobile phase containing 50 mmol/L TCA. Combination of electrochemical (ED) and ultraviolet (UV) detection was used in which ED was responsible for detection of 3-HKN, 5-HTP, 5-HT and 5-HIAA and UV for the others. The influences of potential of ED and wavelength of UV on detection were studied. The optimization of conditions for separation and detection in different biological samples was also discussed.

[Animal experiment of the ketamine effects on traumatic brain injury resulting from impact maxillofacial injury]

OBJECTIVE

To test the effects of ketamine (KET) on traumatic brain injury resulting from impact maxillofacial injury.

METHODS

The rat models with middle serious traumatic brain injury were obtained by falling impaction at maxillofacial region of the rats, then the animals were treated with KET in the early stage, and the alteration of the neural function in those rats was observed at the same time.

RESULTS

There was obvious difference between the rats in the KET-treating groups and the control group. It took about 2 days fewer than that of the control group for rats in the KET-treating group to recover.

CONCLUSION

KET can shorten the recovery time of rats with brain injury resulting from impact maxillofacial injury.

[A study on detecting the gene deletion or loss of heterozygosity by polymerase chain reaction]

The authors investigated the possibility of using PCR to dsetect the deletion of gene or loss of heterozygosity (LOH) of gene in biopsies. With some aids, such as selection of PCR cycle number, choice of internal control and screening of samples, the authors detected the deletion of GSH Clone 7 in nasophryngeal carcinoma (NPC) by PCR-Southern, and successfully found one case which partially deleted GSH Clone 7. This results was confirmed by image densitometry. Through this study, an available method to detect the deletion of gene by PCR is provided.

[Determination algorithms in oscillometric blood pressure measurement]

This paper discusses the method of oscillometric blood pressure determination. A new criterion for systolic pressure and diastolic pressure determination has been proposed, which is based on ratio changes of the oscillation amplitude under a wide normalized range. Primary experiment results show the new criterion is effective.

Utilizing the C-terminal cleavage activity of a protein splicing element to purify recombinant proteins in a single chromatographic step

A conventional affinity protein purification system often requires a separate protease to separate the target protein from the affinity tag. This paper describes a unique protein purification system in which the target protein is fused to the C-terminus of a modified protein splicing element (intein). A small affinity tag is inserted in a loop region of the endonuclease domain of the intein to allow affinity purification. Specific mutations at the C-terminal splice junction of the intein allow controllable C-terminal peptide bond cleavage. The cleavage is triggered by addition of thiols such as dithiothreitol or free cysteine, resulting in elution of the target protein while the affinity-tagged intein remains immobilized on the affinity column. This system eliminates the need for a separate protease and allows purification of a target protein without the N-terminal methionine. We have constructed general cloning vectors and demonstrated single-column purification of several proteins. In addition, we discuss several factors that may affect the C-terminal peptide bond cleavage activity.

Proteasome-mediated degradation of apolipoprotein B targets both nascent peptides cotranslationally before translocation and full-length apolipoprotein B after translocation into the endoplasmic reticulum

A major portion of newly synthesized apolipoprotein B (apoB) is degraded intracellularly. This degradation has been demonstrated to be mediated largely by the ubiquitin-proteasome pathway. We examined whether nascent apoB polypeptides or full-length apoB is selectively retrotranslocated from the endoplasmic reticulum into the cytosol for degradation. Herein, we found that full-length apoB as well as partial-length apoB peptides are ubiquitinated in HepG2 cells, and ubiquitination is an exclusively cytosolic process. Calnexin, which binds specifically to glycoproteins, has been postulated to promote apoB folding and complete translocation; we found that ubiquitinated apoB is bound to calnexin, suggesting that ubiquitinated apoB is glycosylated. In addition to calnexin binding, we have other pieces of evidence that the full-length intracellular ubiquitinated apoB is glycosylated, because (i) it binds to concanavalin A, and (ii) glycan can be demonstrated in the full-length ubiquitinated apoB by a chemical detection method involving oxidation of adjacent hydroxyl groups in the glycan moiety. Because glycosylation occurs inside the endoplasmic reticulum, the full-length glycosylated apoB must have been retrotranslocated into the cytosol for ubiquitination and proteasome-mediated degradation. Next we synchronized translation in HepG2 cells by puromycin treatment. A pulse-chase experiment using [35S]methionine labeling of intracellular apoB in these synchronized cells demonstrated that nascent partial-length apoB peptides are also ubiquitinated cotranslationally. We conclude that the ubiquitin proteasome-mediated degradation of apoB targets both nascent peptides cotranslationally before translocation as well as full-length apoB after its translocation into the endoplasmic reticulum.

Preliminary observation on the correlation between nm23 expression and Ki-67 antigen with early metastasis of human osteosarcoma

OBJECTIVES

To detect the nm23 expression in osteosarcoma, analyze the correlation between nm23 expression and early metastasis and to study the relation between nm23 expression with tumor differentiation and cell proliferation, as defined by Ki-67 labeling.

METHODS

nm23 oncoprotein expression was measured by immunohistochemical staining using formalin fixed, paraffin embedded sections of 39 surgically resected osteosarcomas and was compared with Ki-67 expression, histological findings and early metastasis. In each sample, the grading of immunoreactivity was recorded as 0, 1+, 2+ according to the percentage of nm23 and Ki-67 labeling cells respectively.

RESULTS

The cases with more than 25% positive immunoreactivity of nm23 protein were detected in 48.7% of the total cases. There was no statistical difference between nm23 expression and early metastasis, but the cases with nm23 expression appeared to have a trend to get early metastasis. nm23 expression was significantly correlated with Ki-67 expression, which was associated with differentiation of the tumor cells.

CONCLUSION

The role of nm23 as a tumor metastasis suppressor in osteosarcoma is less prominent. Both nm23 and Ki-67 may help predict the possibility of early metastasis in human osteosarcomas.

[Histological and electrophysiologic changes of injury of dorsal root ganglia]

Injury of dorsal root ganglia (DRG) may cause sensory and motor dysfunction. In order to investigate the changes of somato-sensory evoked potential (SEP) and histological characteristics of DRG in different causes and different periods of injury, fifty-two rabbits were chosed to build the models. The rabbits were divided into 4 groups: Control group (n = 4); mechanical compressing group (n = 16); inflammatory injury group (n = 16); and treatment group (2% lidocaine with hydroprednisone was administered locally, n = 16). After one to eight weeks, SEP was determined and samples of DRG were obtained to observe the histological and ultrastructural changes every week. The result showed that the gap junction of microvascular endothelium in DRG had been destroyed by the mechanical compression was the major cause of the vessel permeability increasing. The increasing of endothelial pinocytic vesicles transportation and widening of endothelial gap junction were the main causes of inflammatory irritation of DRG. The local infiltration with 2% lidocaine and hydroprednisone could obviously ameliorate inflammatory injury in DRG.

Characterization and functional analysis of the cis-autoproteolysis active center of glycosylasparaginase

Glycosylasparaginase is an N-terminal nucleophile hydrolase and is activated by intramolecular autoproteolytic processing. This cis-autoproteolysis possesses unique kinetics characterized by a reversible N-O acyl rearrangement step in the processing. Arg-180 and Asp-183, involved in binding of the substrate in the mature enzyme, are also involved in binding of free amino acids in the partially formed substrate pocket on certain mutant precursors. This binding site is sequestered in the wild-type precursor. Binding of free amino acids on mutant precursors can either inhibit or accelerate their processing, depending on the individual mutants and amino acids. The polypeptide sequence at the processing site, which is highly conserved, adopts a special conformation. Asp-151 is essential for maintaining this conformation, possibly by anchoring its side chain into the partially formed substrate pocket through interaction with Arg-180. The reactive nucleophile Thr-152 is activated not only by deprotonation by His-150 but also by interaction with Thr-170, suggesting a His-Thr-Thr active triad for the autoproteolysis.

Barriers to progress in urinary incontinence: achieving quality assessments

Urinary incontinence is a major care problem in nursing homes. Despite legislation aimed at decreasing its incidence, minimal progress has been made to achieve this goal. Obtaining an accurate assessment about the level and pattern of incontinence will assist caregivers in developing plans to reduce it. This article identifies barriers the authors have encountered in obtaining accurate records in a research project and strategies implemented to overcome these barriers.

Isolation of specific DNA probes for detection of Cryptococcus neoformans

We report the construction of a genomic library and isolation of repetitive DNA probes from Cr. neoformans that are species- and variety-specific. The inserts of the genomic library were in a range of 0.3-1.8 kb, which were in normal distribution in length. Among 592 clones of the genomic library, there were 400(67.6%) clones inserted repetitive DNA sequence and 192(32.4%) inserted single copy DNA sequence of the Cr. neoformans genome. From the library, three specific probes were identified. Clone pCNIIA6 was serotype A-specific, pCNIIB5 species-specific, and pCNIIIG1 variety-specific (var. neoformans). On the basis of the high specificity and sensitivity of the signals observed by hybridization, we suggest that these probes provide a means for both biotyping and early diagnosis of Cr. neoformans.

Small-dose itraconazole pulse therapy in the treatment of onychomycosis

The aim was to evaluate efficacy and tolerance of a short-schedule treatment regimen using a small dose of itraconazole in pulse intermittently. The open study evaluated the pulse therapy consisting of monthly 1-week cycles of oral itraconazole 200 mg daily for 2-3 consecutive months in 42 patients with onychomycosis. After active therapy, patients were evaluated for a maximum period of 1 year. Twelve of 42 patients were considered as being clinically cured, 17 were markedly improved, 11 were improved and two were failures. A mycological examination at the final visit was performed on all patients. Thirty-five were negative and seven were positive. This short treatment was well tolerated, with no adverse reactions, and may offer a new option for treatment of onychomycosis.

[Recovery of motor function of spinal cord with embryonic spinal cord graft in adult rat]

The capacity of embryonic spinal cord tissue in the repair of injured structure of spinal cord has been noted for years. In order to investigate the embryonic spinal cord graft in the repair of motor function of injured spinal cord, the embryonic spinal cord tissue was transplanted to the hemisection cavity in spinal cord in adult rat. One hundred adult Wistar Rats were used to simulate the hemisectional injury of spinal cord by drilling 2-3 mm cavity in lumbar enlargement. Sixty rats were treated with rat embryonic spinal cord tissue grafting while the other forty were chosen as control. The outcome was evaluated according the combined behavioural score (CBS) and motor evoked potential (MEP) in the 1, 2, 4 and 12 weeks. The grafting group was superior to the control as assessed by CBS (P < 0.05), especially within 4 weeks. (P < 0.01). The restoration of the latent peak of early wave(P1, N1) was better in the grafting group, too. This suggested that embryonic spinal cord graft could improve the recovery of motor function of injured spinal cord in adult rat. The effect of the embryonic spinal cord tissue graft might be concerned with its secretion of several kinds of neurotrophic factors, nerve growth factor, nerve transmitted factor, or adjustment of hormone.

[Approximate entropy: a complexity measure suitable for short data]

The definition, algorithm and application of approximate entropy are introduced. A discussion is made on the reason of it merits.

[Mutual regulation of proliferation between pulmonary artery endothelial cells and pulmonary smooth muscle cells in vitro]

Vascular endothelial cell are closely related to vascular smooth muscle cells in structure and function. The interactions between them may play important roles in the modulation of function and structure of vascular wall. In the present study, the mitogenic regulations between cultured new bovine pulmonary arterial endothelial cell (PAEC) and pulmonary arterial smooth muscle (PASM) were investigated. When PAECs and PASMs were mixcultured, 3H-TdR incorporation into the mixed cells decreased significantly (P < 0.001 vs control). When PAECs and PASMs were cultured in conditioned medium from PASMs and PAECs respectively or they were cocultured, the proliferation of PAECs was inhibited while that of PASM was stimulated significantly (P < 0.05 vs control). It was also found that the concentration of cAMP increased but cGMP decreased in cocultured PASMs (P < 0.01 vs control), while the concentration of both cAMP and cGMP decreased significantly in cocultured PAECs (P < 0.01 vs control). These findings suggest that PAECs and PASMs may regulate their proliferation each other through the second messenger system.

Lipoprotein metabolism in the fat Zucker rat: reduced basal expression but normal regulation of hepatic low density lipoprotein receptors

Hyperlipoproteinemia is one of the phenotypic characteristics of the fat Zucker rat that carries a mutation in the leptin receptor gene. In the present study, we studied the regulation of hepatic low density lipoprotein (LDL) receptor expression in lean and fat Zucker rats. Compared with lean rats, the fat ones had a pronounced (approximately 60%) reduction in hepatic LDL receptor expression, whereas the levels of receptor messenger RNA (mRNA) were not reduced. Fat rats had increased levels of very low density lipoproteins and high density lipoproteins, but their plasma apo B100 within LDL was reduced. Challenge with 2% dietary cholesterol for 8 days suppressed hepatic LDL receptor expression in lean animals to similar levels as seen in fat ones, whereas the reduction in mRNA levels was much less pronounced. Treatment with ethynylestradiol (5 mg/kg BW per day) for 4 days strongly stimulated hepatic LDL receptor expression in both lean and fat rats; this treatment also increased LDL receptor mRNA levels, but to a lesser extent. In conclusion, the basal expression of hepatic LDL receptors is reduced in fat Zucker rats, but the capacity for the regulation of the receptors remains intact.

Somatosensory- and motor-evoked potentials in a rabbit model of spinal cord ischemia and reperfusion injury

STUDY DESIGN

Occlusion of the infrarenal abdominal aorta was applied to adult rabbits, which induced spinal cord ischemia, followed by disocclusion and reperfusion. Cortical somatosensory- and motor-evoked potentials were monitored continuously up to 24 hours and correlated to hind limb motor and sensory status.

OBJECTIVES

To investigate cortical somatosensory-, and motor-evoked potentials in the rabbit model of spinal cord ischemia and reperfusion injury, especially their changes during reperfusion and their relationship to hind limb motor and sensory function.

SUMMARY OF BACKGROUND DATA

Various evoked potentials have been widely studied in neurologic prognosis of spinal cord ischemia. Little information is available from previous studies to correlate cortical somatosensory- and motor-evoked potentials with secondary paraplegia occurring during the reperfusion phase.

METHODS

Acute spinal cord ischemia was induced in eight anesthetized rabbits by occlusion of the infrarenal abdominal aorta just beneath left renal artery for 40 minutes. Cortical somatosensory-evoked potentials, elicited by stimulating the posterior tibial nerve and recorded at the skull surface corresponding to sensory projection area, and motor-evoked potentials, elicited by stimulating the skull surface corresponding to the motor projection area and recorded at L4 lamina of the vertebral arch, were monitored immediately before and at different time points during ischemia and reperfusion up to 24 hours after disocclusion. Hind limb motor and sensory functions were evaluated and correlated with cortical somatosensory- and evoked-potentials.

RESULTS

Cortical somatosensory-evoked potentials disappeared gradually after the start of occlusion and reappeared during reperfusion. Motor-evoked potentials did not change significantly during occlusion, but deteriorated after disocclusion; they correlated well with hind limb motor and sensory status.

CONCLUSIONS

Reperfusion injuries to the spinal cord might occur in the rabbit model after disocclusion. Cortical somatosensory-evoked potentials seemed to be a very sensitive index for spinal cord ischemia, whereas motor-evoked potentials correlated well with the course of reperfusion injuries after disocclusion and reflected long-term follow-up hind limb motor function better than cortical somatosensory-evoked potentials.

Novel effects of histamine on lipoprotein metabolism: suppression of hepatic low density lipoprotein receptor expression and reduction of plasma high density lipoprotein cholesterol in the rat

Histamine has been shown to be involved in atherosclerosis and coronary heart disease. Little information is available regarding the effects of histamine on lipoprotein metabolism. In the current study, we investigated the effects of histamine on the expression of hepatic low density lipoprotein (LDL) receptors and on plasma lipoproteins in the rat. Injection of compound 48/80 (C48/80, a histamine releaser) or histamine reduced hepatic LDL receptor expression, but not LDL receptor messenger RNA levels. Oral administration of polymyxin B (an antiendotoxin antibiotic and a histamine releaser) before the injection of C48/80 or histamine did not attenuate their effects. Polymyxin B itself had effects similar to those of C48/80 and histamine on LDL receptors. These results suggest that the effects of histamine are not mediated by the induction of gut-derived endotoxemia. Histamine H2 agonists (dimaprit and impromidine), but not H1 agonists (2-methylhistamine and 2-thiazolylethylamine), also reduced hepatic LDL receptor expression. The suppressive effect of C48/80 on hepatic LDL receptor expression was not attenuated by either the H1 antagonist (chlorpheniramine) or the H2 antagonist (cimetidine). Administration of C48/80 also reduced plasma high density lipoprotein (HDL) cholesterol. The H1 antagonist (chlorpheniramine), but not the H2 antagonist (cimetidine), almost completely reversed the effect of C48/80 on plasma HDL cholesterol. In conclusion, histamine suppresses hepatic LDL receptor expression via a non-H1 receptor-mediated pathway, and histamine reduces plasma HDL cholesterol via an H1 receptor-mediated pathway.

Mesopontine organization of cholinergic and catecholaminergic cell groups in the normal and narcoleptic dog

Canine narcolepsy is a unique experimental model of a human sleep disorder characterized by excessive daytime sleepiness and cataplexy. There is a consensus recognition of an imbalance between cholinergic and catecholaminergic systems in narcolepsy although the underlying mechanisms remain poorly understood. Possible substrates could be an abnormal organization, numbers and/or ratio of cholinergic to catecholaminergic cells in the brain of narcoleptic dogs. Therefore, we sought to characterize the corresponding neuronal populations in normal and narcoleptic dogs (Doberman Pinscher) by using choline acetyltransferase (ChAT), nicotinamide adenosine dinucleotide phosphate (NADPH)-diaphorase, tyrosine hydroxylase (TH), and dopamine beta-hydroxylase (DBH). Cholinergic cell groups were found in an area extending from the central to the gigantocellular tegmental field and the periventricular gray corresponding to the pedunculopontine tegmental nucleus (PPT), the laterodorsal tegmental nucleus (LDT), and the parabrachial nucleus. An almost perfect co-localization of ChAT and NADPH-diaphorase was also observed. Catecholaminergic cell groups detected included the ventral tegmental area, the substantia nigra, and the locus coeruleus nucleus (LC). The anatomical distribution of catecholaminergic neurons was unusual in the dog in two important aspects: i) TH- and/or DBH-immunoreactive neurons of the LC were found almost exclusively in the reticular formation and not within the periventricular gray, ii) very few, if any TH-positive neurons were found in the central gray and dorsal raphe. Quantitative analysis did not reveal any significant differences in the organization and the number of cells identified in the LDT, PPT, and LC of normal and narcoleptic dogs. Moreover, the cholinergic to catecholaminergic ratio was found identical in the two groups. In conclusion, the present results do not support the hypothesis that the neurochemical imbalance in narcolepsy could result from abnormal organization, numbers, or ratio of the corresponding neuronal populations.

[The development of a fluid percussion device for brain injury of animals]

This paper discusses a fluid percussion device for brain injury. The injury is produced by striking the cork with a pendulum dropped from a known fall height to produce transient high pressure through a fluid transfer system. Experimental results show the device has the advantages of making a controllable, repeatable, and precise injury, and it can produce different levels of injury on different animals.

The zebrafish gene cloche acts upstream of a flk-1 homologue to regulate endothelial cell differentiation

The zebrafish cloche mutation affects both the endothelial and hematopoietic lineages at a very early stage (Stainier, D. Y. R., Weinstein, B. M., Detrich, H. W., Zon, L. I. and Fishman, M. C. (1995). Development 121, 3141–3150). The most striking vascular phenotype is the absence of endocardial cells from the heart. Microscopic examination of mutant embryos reveals the presence of endothelial-like cells in the lower trunk and tail regions while head vessels appear to be missing, indicating a molecular diversification of the endothelial lineage. Cell transplantation experiments show that cloche acts cell-autonomously within the endothelial lineage. To analyze further the role of cloche in regulating endothelial cell differentiation, we have examined the expression of flk-1 and tie, two receptor tyrosine kinase genes expressed early and sequentially in the endothelial lineage. In wild-type fish, flk-1-positive cells are found throughout the embryo and differentiate to form the nascent vasculature. In cloche mutants, flk-1-positive cells are found only in the lower trunk and tail regions, and this expression is delayed as compared to wild-type. Unlike the flk-1-positive cells in wild-type embryos, those in cloche mutants do not go on to express tie, suggesting that their differentiation is halted at an early stage. We also find that the cloche mutation is not linked to flk-1. These data indicate that cloche affects the differentiation of all endothelial cells and that it acts at a very early stage, either by directly regulating flk-1 expression or by controlling the differentiation of cells that normally develop to express flk-1. cloche mutants also have a blood deficit and their hematopoietic tissues show no expression of the hematopoietic transcription factor genes GATA-1 or GATA-2 at early stages. Because the appearance of distinct levels of flk-1 expression is delayed in cloche mutants, we examined GATA-1 expression at late embryonic stages and found some blood cell differentiation that appears to be limited to the region lined by the flk-1-expressing cells. The spatial restriction of blood in the ventroposterior-most region of cloche mutant embryos may be indicative of a ventral source of signal(s) controlling hematopoietic differentiation. In addition, the restricted colocalization of blood and endothelium in cloche mutants suggests that important interactions occur between these two lineages during normal development.

Contrasting effects of growth hormone and insulin-like growth factor I on the biological activities of endotoxin in the rat

We previously demonstrated that GH potentiates the biological activities of endotoxin in the rat. In the present study, we wanted to determine if the potentiating effects of GH on the biological activities of endotoxin could be reproduced by insulin-like growth factor I (IGF-I). Endotoxin (5 mg/kg BW) was injected in rats primed with or without GH or IGF-I for 3 days. As expected, endotoxin administration markedly increased circulating tumor necrosis factor (TNF) and interferon-gamma (IFN gamma) and induced organ injury, hypoglycemia, and hyperlipidemia. In GH-primed rats, endotoxin induced a further increase of serum IFN gamma (but not TNF); and five out of six of those rats died within 15 h after giving endotoxin. However, little difference between endotoxin-treated rats with and without IGF-I priming could be seen. Furthermore, IGF-I infusion altered blood glucose, urea, and circulating ICF-I levels more than GH infusion. Therefore, IGF-I does not enhance the biological activities of endotoxin in the rat, suggesting that the enhancement of endotoxin effects by GH is via an IGF-I-independent pathway. Priming rats by GH (but not by IGF-I) induced a further increased response of serum IFN gamma but not TNF to subsequent endotoxin challenge, suggesting that IFN gamma rather than TNF is likely to be involved in this process.

Synthesis of a hexasaccharide acceptor corresponding to the reducing terminus of mycobacterial 3-O-methylmannose polysaccharide (MMP)

The title compound methyl O-(2,6-di-O-benzyl-3-O-methyl-alpha-D-mannopyranosyl)-[(1-->4) -O-(2,6-di-O-benzyl-3-O-methyl-alpha-D-mannopyranosyl)]4-(1-->4) -2,6-di-O-benzyl-3-O-methyl-alpha-D-mannopyranoside (2) was synthesized in a blockwise manner, employing trichloroacetimidate (11) and (20) as glycosyl donors. The strategy relies on the single-step preparation of the 3-O-methyl ethers (4) and (12) as starting materials. Since all intermediates contain one or more OCH3 groups, they are easily identified by NMR spectroscopy using the methyl proton signals. Compound 2 corresponds to the reducing terminal hexasaccharide of mycobacterial 3-O-methyl-mannose polysaccharide (MNP). MMP has the unusual property of stimulating the fatty acid synthetase multienzyme complex. Compound 2 can serve as a suitable glycosyl acceptor for the synthesis of extended fragments of MMP.

Major histocompatibility class II molecules in the CNS: increased microglial expression at the onset of narcolepsy in canine model

Human narcolepsy is a neurological disorder known to be closely associated with HLA-DR2 and DQB1*0602. Because most autoimmune diseases are HLA-associated, a similar mechanism has been proposed for narcolepsy. However, neither systemic nor CNS evidence of an autoimmune abnormality has ever been reported. In this study, major histocompatibility (MHC) class I and class II expression was studied in the CNS of human and canine narcoleptics using immunohistochemistry and Northern analysis. Results indicated that canine narcolepsy is associated with a significant increase of MHC class II expression by the microglia. Moreover, the highest values were found between 3 and 8 months of age, strikingly concomitant to the development of narcolepsy in the canine model. In humans, class II expression was not found significantly different between control and narcoleptic subjects. This result could be explained by the old age of the subjects (69.86 +/- 5.31 and 68.36 +/- 4.74 years in narcoleptics and controls, respectively), because class II expression is significantly correlated with age in both humans and dogs. For the first time, this study demonstrated that the expression of MHC class II molecules in the CNS is age-dependent and that a consistent increase of their expression by the microglia might be critically involved in the development of narcolepsy.

[Isolation of specific DNA probes from Cryptococcus neoformans]

OBJECTIVE

To construct plasmid library and screen specific DNA probes for Cryptococcus neoformans.

METHODS

Serotype A Cryptococcus neoformans was used as the study strain, plasmid pUC18 as vector, and Escherichia coli JM103 as host cell. The plasmid library of cryptococcus neoformans was constructed (pCN). Other pathogenes causing affection diseases which should be distinguished from cryptococcusis clinically, and other fungi similar to Cryptococcus neoformans with physiological and biochemical characteristics were used as a distinguishing system, specific colonies were screened by hibridization in double steps.

RESULTS

The inserts of the library were 280 to 1800 base pairs and 580 base pairs in average length. Repeated sequence was 32.43% and single copy sequence was 67.57% in genome of cryptococcus neoformans respectively. Three specific colonies were isolated from the library. Colony pCNII A6 was serotype A specific, pCNII B5 species specific and pCNIII G1-specific for var. neoformans.

CONCLUSION

A rapid diagnosis of Cryptococcus neoformans infection at early stage can be made by using species-specific probe, and serotype and variaty of neoformans and gattii be distinguished in epidemic study.

[Some aspects on surgical treatment of infratemporal fossa malignancies]

Thirteen patients with infratemporal fossa malignancies treated in the Sichuan Cancer Hospital from 1988 to 1993 are reported. All cases were treated surgically combined with pre-operative and post-operative radiotherapy with or without chemotherapy. The survival rate of the patients with survival period beyond 2 years was 53.8%. The survival was associated with the extent of dissection (P < 0.01). The operation value, surgical approaches, resection range, bone boundary of surgery, stylohamular line and repair are analysed and discussed.

Growth hormone potentiates the in vivo biological activities of endotoxin in the rat

To investigate if growth hormone (GH) alters the effects of endotoxin in rats, endotoxin (5 mg kg-1 body weight) was injected into normal rats and into rats primed with GH for 3 days. Endotoxin had injurious effects on renal and liver function and induced hypoglycaemia and hyperlipidaemia as expected. GH-primed rats became extremely sick after endotoxin challenge and had more marked abnormalities of renal and liver function and much more pronounced hypoglycaemia and hyperlipidaemia than non-primed rats. It is concluded that growth hormone potentiates the in vivo biological activities of endotoxin in the rat. The results may also suggest that caution should be exerted when considering GH treatment in catabolic situations with endotoxaemia and that special attention should be paid to the prevention of infection during GH therapy in such situations.

Endotoxin suppresses rat hepatic low-density lipoprotein receptor expression

Endotoxin induces hyperlipidaemia in experimental animals. In the current study, we investigated whether endotoxin alters hepatic low-density lipoprotein (LDL) receptor expression in rats. Endotoxin treatment suppressed hepatic LDL receptor expression in a dose- and time-dependent manner. Eighteen hours after intraperitoneal injection of increasing amounts of endotoxin, LDL receptor and its mRNA levels were determined by ligand blot and solution hybridization respectively. LDL receptor expression was inhibited by about 70% at a dose of 500 micrograms/100 g body weight. However, LDL receptor mRNA levels were markedly increased in all endotoxin-treated groups at this time point (by 83-136%; P < 0.001). Time-course experiments showed that LDL receptor expression was already reduced by 48% 4 h after endotoxin injection and was maximally reduced (by 63-65%) between 8 and 18 h. Changes in hepatic LDL receptor mRNA showed a different pattern. By 4 h after endotoxin injection, LDL receptor mRNA had decreased by 78% (P < 0.001). However, by 8 h after endotoxin injection, LDL receptor mRNA had returned to levels similar to controls, and 18 and 24 h after endotoxin injection, they were increased by about 60% (P < 0.05). Separation of plasma lipoproteins by FPLC demonstrated that endotoxin-induced changes in plasma triacylglycerols and cholesterol were due to accumulation of plasma apolipoprotein B-containing lipoproteins among very-low-density lipoprotein, intermediate-density lipoprotein and LDL. It is concluded that endotoxin suppresses hepatic LDL receptor expression in vivo in rats.

Activation of glycosylasparaginase. Formation of active N-terminal threonine by intramolecular autoproteolysis

The activation mechanism of glycosylasparaginase of Flavobacterium meningosepticum has been analyzed by site-directed mutagenesis and activation of purified precursors in vitro. Mutation of Thr-152 to Ser or Cys leads to gene products that are not activated in vivo but are activated in vitro because processing of the mutant precursors is inhibited by certain amino acids in the cell. Kinetic studies reveal that activation is an intramolecular autoproteolytic process. The involvement of His-150 and Thr/Ser/Cys-152 in activation suggests that autoproteolysis resembles proteolysis by serine/cysteine proteases. Multiple functions of the highly conserved active threonine residue are implicated.

[A comparison between astrocytoma cells and the developing astrocytes in human embryo brain by electron microscopy]

60 cases of astrocytoma of brain and 8 human embryo brains were studied with light and electron microscopy. The 5 types of tumor cells in astrocytoma include the undifferentiated, pre-astrocyte, astrocyte gemistocyte and tumor giant cells. Some similarities were found between the ultrastructure of astrocytoma and that of the developing astrocyte, the tumor cells somewhat resembling the cells of developing astrocytes. But certain differences were observed, the tumor cells were usually polymorphic with increased chromatin in nucleus, and asynchronism between nucleus and cytoplasm differentiation was sometimes found. The current nomenclature and classification of astrocytoma were evaluated and discussed, the author's opinion on classification was presented.

Phosphorylation and nuclear localization of the hepatitis B virus core protein: significance of serine in the three repeated SPRRR motifs

Hepatitis B virus core protein (antigen) is an important serologic marker of hepatitis B virus infection. This protein is found in the cytoplasm or the nuclei, or both, of infected hepatocytes. A nuclear localization signal has previously been identified in the core protein sequence. This signal overlaps three repeated SPRRR motifs. In this report, we demonstrate that substitution of all of the serine residues in these three SPRRR motifs with alanine can prevent almost entirely the phosphorylation of the core protein in Huh-7 hepatoma cells, enhance nuclear localization of the core protein in both Huh-7 and nonhepatic cells, and abolish cell cycle regulation of nuclear localization of the core protein. Since the three core protein mutants which retained only one serine residue of each of the three SPRRR motifs could be phosphorylated to similar degrees, these three serine residues likely could serve as the acceptor sites for phosphorylation with equal efficiency. These results, together with the observation that the three SPRRR motifs overlap the nuclear localization signal of the core protein, raise the possibility that nuclear localization of the core protein is negatively regulated by phosphorylation of the serine residues in the SPRRR motifs.

Upregulation of low density lipoprotein receptor activity by tumor necrosis factor, a process independent of tumor necrosis factor-induced lipid synthesis and secretion

It has been shown that tumor necrosis factor (TNF) rapidly upregulates expression of the low density lipoprotein (LDL) receptors on Hep G2 cells and acutely stimulates hepatic lipid synthesis and secretion in vivo. It may thus be possible that TNF-induced expression of LDL receptors is secondary to a decrease in cellular cholesterol content caused by TNF-stimulated lipid secretion. In order to know whether TNF upregulates LDL receptors by depletion of the cellular cholesterol content, the present experiments were designed to study the temporal relationship between TNF-stimulated expression of LDL receptor activity and TNF-induced changes in lipid synthesis and secretion in an in vitro setting by using Hep G2 cells (a highly differentiated human hepatoma cell line) as a hepatocyte model. Hep G2 cells were incubated with TNF (usually 2.5 nmol/L) for certain periods, and LDL receptor activity was evaluated by measuring [125I]LDL binding at 4 degrees C; lipid synthesis and secretion were assayed by measuring [3H]glycerol incorporation into triglycerides and phospholipids as well as [14C]acetate incorporation into cholesterol. We found that a 30-h exposure of the cells to TNF was needed for the effect of TNF to be seen on lipid synthesis and secretion as measured by incorporation of [3H]glycerol into triglycerides and phospholipids, whereas TNF rapidly (in several hours) upregulated LDL receptor activity. TNF stimulated triglyceride synthesis, but did not stimulate phospholipid synthesis. On the other hand, TNF stimulated phospholipid secretion, but did not stimulate triglyceride secretion. Exposure of the cells to TNF for 16 or 24 h neither decreased cholesterol synthesis nor stimulated cholesterol secretion as measured by [14C]acetate incorporation into cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)