Expression of gamma-glutamyl transpeptidase during pouch carcinogenesis is not oncofetal

gamma-glutamyl transpeptidase (GGT) is not histochemically detectable in normal adult hamster pouch epithelium but markedly increased during pouch carcinogenesis. The possibility that the increase in GGT activity during pouch carcinogenesis reflects dedifferentiation of cells remains to be answered. The distribution of GGT in fetal and neonatal hamster tissues is unknown. The objective of this study was to determine GGT activity histochemically during hamster pouch development and during development of hamster oral and peri-oral structures, and several extra-oral tissues and organs. High GGT activity was seen mainly in epithelial cells exhibiting marked secretory or absorptive functions. Occasionally, GGT activity was also seen in mesenchymal cells. No GGT activity was noted at any stage of pouch development. The results suggest that the expression of GGT during pouch carcinogenesis represents an acquired phenotype instead of re-expression of a phenotype that is present during normal embryonic development. The results also support the hypothesis that GGT plays an important role in transportation.

Effects of melatonin implants in spring on testicular regression and moulting in adult male raccoon dogs (Nyctereutes procynoides)

Six male raccoon dogs were treated with constant-release implants of melatonin on 29 March, when the animals still had mature spermatozoa and a winter coat. Six untreated animals served as controls. High serum concentrations of melatonin were found in the treated animals throughout the study period (182.2 and 38.5 pg ml-1 in April and August, respectively). The high serum concentrations of prolactin in April and May (18.9 and 15.7 ng ml-1, respectively) in the controls were not seen in the treated animals. Testicular regression, judged by width of the testis and stage of spermatogenesis, was slowed after melatonin administration. Testis width from April to June and stage of spermatogenesis in May and June were greater in the treated animals than in the controls; however, from July onwards the differences between the two groups were no longer significant. Serum concentrations of testosterone remained low (below the detection limit in most cases) in both treated and control animals throughout the study period. Melatonin treatment also affected moulting, which was assessed by changes in the number of growing and mature underfur hairs per bundle and the percentage of bundles with a growing guard hair. The treated animals showed a more rapid shedding of mature underfur hairs and growth of new underfur hairs 6 weeks after melatonin implantation compared with the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hemodynamic changes in portal system after transjugular intrahepatic portosystemic shunts (TIPS)]

In this study portal venous flow (PVF), splenic venous flow (SPVF), hepatic artery volume (HAV), and portal pressure were measured before and after TIPS in 11 patients with portal hypertension. The results were compared with those of normal controls. In the normal controls PVF averaged 947.2 +/- 133.4ml/min, SPVF 239.6 +/- 116.3ml/min, and HAV 241.6 +/- 78.8ml/min. In the TIPS group before and after TIPS, PVF was 883.2 +/- 233.4ml/min vs. 958.7 +/- 185.2ml/min; SPVF was 448.9 +/- 111.6ml/min vs. 333.1 +/- 101.5ml/min; HVP was 225.3 +/- 122.7ml/min vs. 249.3 +/- 103.8ml/min. Portal pressure dropped from 3.94kPa +/- 0.46 to 2.52 +/- 0.60kPa after TIPS. We conclude that in patients after TIPS portal pressure drops blood flow in the truck of the portal vein increases, flow of hepatic tissue decreases, and blood flow in splenic vein decreases. Blood flow in hepatic aftery was not significantly changed.

DNA ligase I mediates essential functions in mammalian cells

DNA replication, repair, and recombination are essential processes in mammalian cells. Hence, the application of gene targeting to the study of these DNA metabolic pathways requires the creation of nonnull mutations. We have developed a method for introducing partially defective mutants in murine embryonic stem cells that circumvents the problem of cellular lethality of targeted mutations at essential loci. Using this approach, we have determined that mammalian DNA ligase I is essential for cell viability. Thus, DNA ligases II and III are not redundant with DNA ligase I for the function(s) associated with cell proliferation. Partial complementation of the lethal DNA ligase I null mutation allowed the creation of deficient embryonic stem cell lines. We found that a wild-type DNA ligase I cDNA, as well as a variant DNA ligase I cDNA, was able to rescue the lethality of the homozygous null mutation, whereas an N-terminal deletion mutant consisting of the minimal DNA ligase I catalytic domain was not. This observation demonstrates that sequences outside the DNA ligase I catalytic domain are essential for DNA ligase I function in vivo.

Fractal dimension of exon and intron sequences

In this paper, the concept of fractal is applied to describe the features of nucleotide sequences. We introduce the mapping from nucleotide sequences to two-dimensional metric space. Then we use this mapping to study quantitatively the self-similarity of exon and intron sequences in different scales. We find that self-similarity exists in the geometrical range and main range of a nucleotide sequence and define the fractal dimension in these ranges. The results show that the fractal properties of exon sequences are quite different from those of introns, reflecting their difference in structure and function. The fractal dimension of the geometrical range may be used to predict the exon regions of a raw nucleotide sequence.

Regulation of a muscle-specific transgene by retinoic acid

Retinoic acid (RA) has been shown to have variable effects on myogenic differentiation in cell culture. The application of RA on primary cultures of embryonic somites, limb buds, and neonatal limbs inhibited myogenic differentiation in a dose-dependent way as indicated by the repression of: (a) myotube formation, (b) myosin heavy chain protein accumulation, (c) myosin light chain (MLC) 1/3, alpha sk-actin and myogenic factor transcript expression. Expression of retinoic acid receptors (RAR) was also affected by RA treatment, specifically RAR gamma transcripts were induced. To further understand the pleiotropic action of RA on myogenesis, we took advantage of two muscle-specific transgene markers which consisted of CAT reporter genes driven by regulatory elements either from the myosin light chain 1/3 locus (MLC-CAT) or the alpha-skeletal actin gene (alpha sk actin-CAT). RA inhibited MLC-CAT transgene but not alpha sk actin-CAT transgene expression in primary cultures from these mice. Analysis of MLC-CAT expression in transgenic mouse primary cultures and in stably transfected C2C12 cells demonstrated that repression of MLC-CAT activity by RA was dependent upon diffusible factors in chick embryo extract. We hypothesize that during development, the pleiotropic effects of RA on myogenesis do not depend solely on the distribution and concentration of RA itself, but are also influenced by extracellular signals in the embryonic environment.

In vitro and ex vivo activities of antimicrobial agents used in combination with clarithromycin, with or without amikacin, against Mycobacterium avium

MICs of clarithromycin, amikacin, isoniazid, rifabutin, ciprofloxacin, sparfloxacin, ethambutol, and clofazimine were determined for six isolates of Mycobacterium avium complex (MAC) from AIDS patients both by the radiometric method and by an ex vivo model of infection in human macrophages. The median MICs in macrophages were similar or slightly lower than values found in broth, except for amikacin, which had slightly higher MICs inside the cells. Combinations of clarithromycin with other antimicrobial agents showed that clarithromycin-clofazimine and clarithromycin-rifabutin were synergistic on five of six strains while clarithromycin-amikacin and clarithromycin-isoniazid were antagonistic on one and two strains, respectively. The addition of amikacin made the combinations of clarithromycin-clofazimine and clarithromycin-ethambutol synergistic against all the MAC strains. In the macrophage model, the combination of clarithromycin-clofazimine (mean survival, 21%) and clarithromycin-rifabutin (mean survival, 29%) showed a strong reduction in viable counts compared with single drugs, while clarithromycin-amikacin was less active than single drugs alone. In general, the addition of amikacin did not improve the activity of the combinations, except for clarithromycin-isoniazid-amikacin (mean survival, 19%), which was significantly more active than either clarithromycin-isoniazid or clarithromycin-amikacin. The use of the macrophage model can suggest new combinations of antimicrobial agents with anti-MAC activity which, on the basis of their in vitro effectiveness, would probably be disregarded for assay in animal models.

Clastogenic effects of 1,3-butadiene and its metabolites 1,2-epoxybutene and 1,2,3,4-diepoxybutane in splenocytes and germ cells of rats and mice in vivo

Clastogenicity of 1,3-butadiene (BD), 1,2-epoxybutene (EB), and 1,2,3,4-diepoxybutane (DEB) was studied in splenocytes and germ cells of rats and mice by means of micronucleus assays (cytokinesis-block method for splenocytes, suspension method for germ cells). Inhalation exposure of mice to 200, 500, or 1,300 ppm BD (6 h/d; 5 days) induced significant chromosome damage in spermatocytes at the preleptotene stage. EB and DEB induced significant amounts of clastogenic damage in splenocytes and spermatocytes of rats and mice. The lowest tested effective doses for mice and rats were, respectively, 40 and 80 mg/kg for EB, and 15 and 30 mg/kg for DEB. In splenocytes, 80 mg EB/kg induced 3.6 times more MN in mice than in rats, whereas 30 mg DEB/kg induced the same amount of damage in both species. Damage in germ cells of mice was induced in early spermatocytes treated with 40 and 80 mg EB/kg, and in late spermatocytes exposed to 30 mg DEB/kg. In rats, 40 mg EB/kg induced damage in early spermatocytes, whereas 80 mg EB/kg induced chromosomal damage in early and late spermatocytes. In rats treated with DEB, clastogenic damage was induced in spermatocytes at preleptotene, zygotene, diplotene, and diakinesis stages. When the clastogenic potential of EB and DEB in splenocytes and germ cells of mice and rats was compared, DEB always showed a stronger effect than EB. Body weight, testis weight, ratio of testis weight to body weight, and ratio of Golgi to Golgi + cap phase spermatids were used as parameters for toxicity. Exposures to 500 and 1,300 ppm BD were somewhat toxic to mice. Doses of 80 mg EB/kg and 30 mg DEB/kg exhibited toxic effects in mice and rats.

The expression of placental glutathione-s-transferase (gst-pi) in human normal salivary-glands and tumors

Immunohistochemical localization of placental glutathione S-transferase (GST-pi) in normal and inflammatory salivary glands (74 cases) and tumors (71 cases) was studied. In the normal and inflamed salivary glands of all locations (including major and minor salivary glands), the ductal epithelial cells showed moderate to strong GST-pi staining, myoepithelial cells showed weak staining and the acinar cells were negative. The staining pattern of the tumor cells was similar to that of their normal counterparts. The tumor cells were generally positive with GST-pi staining except those tumor cells demonstrating acini differentiation (serous cells in acinic cell carcinoma, mucous cells in mucinous cystadenoma and mucoepidermoid carcinomas). Most of the salivary gland tumors, benign or malignant, showed a weak GST-pi staining. Only mucoepidermoid carcinomas demonstrated significantly increased GST-pi reactivity compared to other tumors (p<0.0001), which may be a reflection of both malignancy and squamous differentiation of the tumor. The marked increase in GST-pi activity in mucoepidermoid carcinomas may be useful in serological screening of recurrent and metastatic mucoepidermoid carcinomas.

Increased frequencies of micronuclei in early spermatids of rats following exposure of young primary spermatocytes to acrylamide

The 'suspension method' for detection of micronuclei in early spermatids (Golgi phase 1 + 2) of rats was used to study induction of chromosomal damage in spermatocytes exposed to single (50 and 100 mg/kg) or fractionated (4 x 50 mg/kg; 24-h intervals) doses of acrylamide. Animals were killed at different time intervals after treatment to measure induction of damage in different stages of spermatocyte development. A statistically significant enhancement of micronucleus frequencies was found after exposure of pre-leptotene spermatocytes to a single dose of 100 mg/kg (days 18 and 20 after treatment) or a fractionated dose of 4 x 50 mg/kg (day 19). In the latter case there was also a significant effect in zygotene spermatocytes that were sampled 15 days after treatment. Comparative studies indicated that the original 'suspension method' can be simplified by omitting enzyme treatments for the release of germ cells from the seminiferous tubules. In the present acrylamide study the old and new procedures gave similar results.

[Effects of fibronectin on cell attachment and migration of human tongue squamous cancer line Tca8113]

By using the cell culture technique in vitro, quantitative studies were carried out to test the effects of fibronectin (FN) on cell biological behaviour of human tongue squamous cancer line Tca8113 in terms of cell attachment to rat-tail collagen substrata supplemented with different concentration of FN or/and anti-FN serum as well as cell migrating distance from the agarose drop cultured with different media containing FN or/and anti-FN serum. The results displayed that FN could increase the density of cells attached to collagen substrata; the cell attachment was dose-dependent on FN. In addition, cell migration from the agarose drop might be induced and cell motility might be promoted by FN. Anti-FN serum could abolish or weaken the above-mentioned FN effects.

A single promoter sequence recognized by a newly identified alternate sigma factor directs expression of pathogenicity and host range determinants in Pseudomonas syringae

A conserved sequence motif associated with transcription of avr genes was identified in the promoter regions of six Pseudomonas syringae pv. syringae Pss61 hrp operons. A 34-bp fragment carrying this motif was cloned from the HrpZ promoter region and was shown to confer HrpL-dependent promoter activity. Expression of pathogenicity and host range determinants in P. syringae strains is thus directed by the apparent alternate sigma factor HrpL.

[Changes in cell spreading area and cell surface morphology of Tca8113 line affected by fibronectin]

Morphometric changes in cell spreading area and morphological alternation in cell surface of human tongue squamous cancer line Tca8113 on rat-tail collagen substrata supplemented with different concentration of FN and/or anti-FN serum were quantified and observed with cell culture technique as well as light and scanning electron microscopes. It was found that FN could increase the cell spreading area and also area of lamellar cytoplasm of Tca8113 cells on collagen substrata, and that cells grown on FN-collagen substrata tended to flatten out, stretch out more filopodia, and sink more deeply into the substrata with the FN concentration. The results indicated that FN might relate closely to certain stages in the process of tumor invasion.

[Immunohistochemical observation of anti-human hepatocellular carcinoma monoclonal antibody HL2 in cancers]

Molecular weight of human hepatocellular carcinoma (HCC)-associated antigen-HL2 antigen was detected to be about 50,000 dalton by SDS-PAGE and Western blot. One hundred and twenty-seven paraffin sections of cancers and pathological liver tissue were tests by ABC immunohistochemical staining. MAb HL2 reacted with 62.7% HCC and also with 8 of the 10 stomach carcinomas but only with a few other digestive system carcinomas (pancreas carcinoma, rectum carcinoma and duodenum carcinoma) and hepatitis. MAb HL2 was negative in hepatocirrhosis and other tumors (vesica carcinoma, skin carcinoma, breast carcinoma, neurogliocytoma and carcinoma of the lung). The results suggest that MAb HL2 has values in diagnosis of HCC and differential diagnosis between HCC and other tumours. HL2 antigen might be a new tumor-associated antigen (TAA). Further study of HL2 antigen will significantly show the actions of TAA in the occurrence and development of tumor.

[Subclavian steal syndrome: a report of 25 cases]

From 1982 to 1992, 25 patients with subclavian steal syndrome (SSS) were admitted with 20 undergoing surgery. Etiology included atherosclerosis 56% (14/25), Takayasu's disease 36% (9/25), 14 of them were smokers. Stenosis or occlusion of the left subclavian artery were found in 14, the right in 7, and bilateral in 4. 14 cases had vertigo symptoms, 24 cases had claudication of the arm, 9 of them complained transient ischemic attack (TIA). Carotid to subclavian bypass were performed for 15 cases. Two patients underwent axilloaxillary bypass with evidence of both clinical and laboratory improvement. Aorta-Carotid graft bypass was done in 2 cases with good result in one. PTA was done for a girl with innominate severe stenosis but symptom recurred three months later. Symptoms of the upper extremity ischemia were relieved in 75% of the patients, and of the cerebrovascular ischemia in 50%. Our conclusion is that surgical therapy remains the treatment of choice in symptomatic patients.

Increase in placental glutathione S-transferase in human oral epithelial dysplastic lesions and squamous cell carcinomas

This study investigated the immunohistochemical expression of human placental glutathione S-transferase (GST-pi) in the epithelium of oral premalignant and malignant lesions. Epithelial lining of normal oral mucosa, hyperplastic lesions and oral epithelium exhibiting mild dysplasia showed weak to moderate GST-pi staining. Moderate epithelial dysplasia revealed an increased antibody content while severe dysplasia, carcinoma-in-situ (CIS) and squamous cell carcinoma (SCC) demonstrated markedly increased antibody binding. The GST-pi staining was evident mainly in the cytoplasm. Severe dysplasia, CIS and SCC were also characterized by areas of cells with intensive nuclear GST-pi staining. These findings support the hypothesis that GST-pi plays a role in human oral carcinogenesis and may be used as a tumor marker for human oral premalignant and malignant lesions.

Induction of IL-1 beta, IL-6, TNF-alpha, GM-CSF and G-CSF in human macrophages by smooth transparent and smooth opaque colonial variants of Mycobacterium avium

Both smooth transparent (SmT) and smooth domed-opaque (SmD) colonial variants were obtained from a strain of Mycobacterium avium isolated from a patient with AIDS. The two variants showed similar biochemical characteristics but SmT bacteria proliferated better than SmD bacteria inside human macrophages and were much less capable than the SmD variant of inducing the release of IL-1 beta, IL-6, TNF-alpha, GM-CSF and G-CSF, after incubation for either 3 or 6 days. As cytokines are important extracellular signals for immune cells, the lack of induction observed in SmT-infected macrophages may be one of the pathogenic mechanisms of M. avium.

Identification of a putative alternate sigma factor and characterization of a multicomponent regulatory cascade controlling the expression of Pseudomonas syringae pv. syringae Pss61 hrp and hrmA genes

The Pseudomonas syringae hrp and hrmA genes controlling pathogenicity and elicitation of the hypersensitive response and the avr genes controlling host range have been shown previously to be regulated by carbon, nitrogen, pH, osmolarity, and hypothetical plant factors. In P. syringae pv. syringae Pss61, inactivation of hrp complementation groups II and XIII reduced expression of a plasmid-borne hrmA'-lacZ fusion. The hrp regions II and XIII were cloned on separate plasmids and shown to enhance the activity of the hrmA promoter in Escherichia coli MC4100 transformants at least 100-fold. The nucleotide sequence of region XIII revealed two open reading frames (hrpR and hrpS) whose deduced products share homology with P. syringae pv. phaseolicola NPS3121 HrpS and are both related to the NtrC family of two-component signal transduction systems. HrpR and HrpS differ from most members of the protein family by lacking an amino-terminal domain which modulates the regulatory activity. A single open reading frame, hrpL, whose product shares homology with AlgU, a putative alternate sigma factor of P. aeruginosa, as well as with the related alternate sigma factors was identified within region II. Key domains are partially conserved. Inactivation of hrpS in Pss61 repressed expression of a plasmid-borne hrpL'-lacZ fusion carried by pYXPL1R, and transformation of MC4100(pYXPL1R) with a plasmid carrying hrpRS increased hrpL promoter activity at least 200-fold. Neither hrpS nor hrpR, when cloned on separate plasmids, activated the hrpL promoter activity individually. The expression of hrpL when directed by a lac promoter was sufficient to express a set of plasmid-borne hrmA'-, hrpJ'-, and hrpZ'-lacZ fusions independently of other hrp genes. The results indicate that hrpRS and hrpL are part of a regulatory cascade in which HrpR and HrpS activate expression of hrpL and HrpL, a putative sigma factor, induces expression of HrpL-responsive genes.