Two truncated forms of rat insulin receptor-related receptor

The insulin receptor-related receptor (IRR) (1271 amino acids) is expected to have unique functions as a novel member of the insulin receptor family. In this paper, we report two alternatively spliced variants of rat IRR mRNA, which are predicted to encode two truncated forms of IRR, sIRR-1 (410 amino acids) and sIRR-2 (469 amino acids). The amino acid sequence of sIRR-1 is identical to the N-terminal 410-amino acid sequence of IRR. sIRR-2 has an additional 59-amino acid insertion in the C-terminal region. Both truncated forms retain the N-terminal and cysteine-rich domains but lack the transmembrane and intracellular tyrosine kinase domains, indicating that the truncated forms are the secreted forms. The translation products of the truncated form mRNAs were detected in the stomach and kidney by Western analysis. However, the physiological significance of the secreted forms remains to be elucidated.

Cloning, expression and characterization of horse L-ferritin in Escherichia coli

Horse L-ferritin cDNA was cloned from horse liver, and the base sequence was determined. The L-ferritin was expressed using pTZ18U encoding lac promoter, and found to possess an additional 8-amino acid sequence at the N-terminus as compared with commercially obtained horse spleen (natural) ferritin. It was determined that there was Pro at position 94 in both the recombinant and natural L-ferritin, although it was previously reported that Leu was in this position in the natural species. Transmission electron microscopy showed that this recombinant ferritin formed a 24-mer shell.

Nicotinic acetylcholine receptor mRNAs in myasthenic thymuses: association with intrathymic pathogenesis of myasthenia gravis

Reverse transcription and the polymerase chain reaction showed that the alpha-, beta- and gamma-subunit genes of nicotinic acetylcholine receptor (AChR) in human skeletal muscle were expressed in myasthenia gravis (MG) thymuses (3 thymomas and 7 hyperplastic thymuses). A study of the expression of these subunit mRNAs in a variety of human tissues showed that alpha-subunit mRNA was expressed in human thymus and cerebral cortex, and that all three subunits were expressed only in human child thymus. Our results suggest that a complete AChR similar to extrajunctional (embryonic) muscle AChR is expressed in MG thymuses and that intrathymic AChR might be the primary antigen which induces autoimmune responses to muscle AChR.

Enhancement of extracapsular polysaccharide synthesis in Klebsiella pneumoniae by RmpA2, which shows homology to NtrC and FixJ

We determined the complete nucleotide sequence of a 2.1-kb HindIII-EcoRI fragment that was cloned from a resident large plasmid of Klebsiella pneumoniae Chedid, a highly virulent and mucoviscous strain of the O1:K2 serotype. This fragment encoded an ability to enhance K2 capsular polysaccharide synthesis in K. pneumoniae, and a 636-bp open reading frame (rmpA2) was found. The 411-bp rmpA reported to be involved in the virulence and mucoid phenotypes of K. pneumoniae by Nassif et al. (Mol. Microbiol. 3:1349-1359, 1989) was a part of rmpA2. Eighty percent homology in nucleotide sequence was found between rmpA2 and rmpA in the corresponding regions. The central domain of the deduced amino acid sequence of RmpA2 showed considerable homology to the central domains of NtrC of K. pneumoniae and Escherichia coli, to which the sigma factor of RNA polymerase binds. The C-terminal domain of RmpA2 also demonstrated considerable homology with the putative helix-turn-helix motifs of LuxR of Vibrio fischeri and FixJ of Rhizobium meliloti. Moreover, RmpA2 also showed some homology in its N- and C-terminal regions to those of RcsA, a transcriptional activator for colanic acid synthesis in E. coli. On the other hand, a sequence upstream of rmpA2 was found to be highly homologous to insertion sequence 3 of members of the family Enterobacteriaceae. Southern hybridization analysis suggested that rmpA2 exists on the large plasmids of all mucoviscous virulent K2 strains but not on those of the slightly mucoviscous avirulent strains. Freeze substitution electron microscopy and fluorescent-antibody staining with anti-K2 serum revealed that K. pneumoniae Chedid has a dense and thick capsule (180 nm) with dense extracapsular substance, whereas K. pneumoniae K2-215, one of the slightly mucoviscous and avirulent strains, has a capsule which is looser and thinner (120 nm) than that of strain Chedid and no extracapsular substance. Introduction of rmpA2 into K2-215 as well as reference strains K. pneumoniae K9 and K72 resulted in a change of the colony phenotype to highly mucoviscous through abundant production of extracapsular substance which reacted with anti-K2, -K9, or -K72, respectively, as did their parental strains. From these results, it is suggested that RmpA2 belongs to the family of transcriptional regulators and confers a highly mucoviscous phenotype on cells of various serotypes of K. pneumoniae by enhancing extracapsular polysaccharide synthesis.

Conversion of a NADPH-dependent aldehyde reducing enzyme into aldose reductase

1. Aldose reductase, aldehyde reductase and high-Km aldose reductase were purified from the inner medulla of dog kidney. 2. Compared with aldose reductase, high-Km aldose reductase had a lower isoelectric point, a lower activity for aldo-sugars and a lower sensitivity for aldose reductase inhibitors, and it was not activated by sulfate ions. Both reductases had the same molecular weight (38,500) and immunochemical properties. 3. High-Km aldose reductase was easily converted into an aldose reductase-like enzyme, namely a generated reductase upon incubation in neutral buffer solution. 4. The generated reductase was identical with aldose reductase with respect to the isoelectric point, substrate specificity, activation by sulfate ions and IC50 values for aldose reductase inhibitors. The generated reductase revealed immunochemical identity with aldose reductase as well as high-Km aldose reductase.

Isolation of rfb gene clusters directing the synthesis of O polysaccharides consisting of mannose homopolymers and serological analysis of lipopolysaccharides

Four serotypes of two genera, Escherichia coli O8 and O9 and Klebsiella O3 and O5, produce the O polysaccharides consisting of mannose homopolymers. Previously, we reported the isolation and expression of E. coli O9 rfb in E. coli K-12 strains (Kido et al, J. Bacteriol., 171: 3629-3633, 1989). In this study, R' plasmids carrying his-rfb region of the other three strains were isolated and expressed in E. coli K-12 strain. Serological study of lipopolysaccharides (LPS) synthesized in E. coli K-12 strain was carried out. His-linked rfb genes from E. coli O9 and Klebsiella O3 directed the synthesis of O polysaccharides with the same antigenicity as those of the parental strains in E. coli K-12 strain. On the other hand, rfb genes from E. coli O8 and Klebsiella O5 directed the synthesis of O polysaccharides which were antigenically not identical but partially common to those of the parental strains. A rough strain derived from E. coli O8 synthesized LPS which showed the identical antigenicity as the wild strain when the his-rfb region of E. coli O8 was introduced. The results suggest that some genes located distantly from his are additionally required to complete the synthesis of O polysaccharides of E. coli O8 and Klebsiella O5.

Brefeldin A blocks the cytotoxicity of T cell receptor alpha/beta and gamma/delta cytotoxic T lymphocyte clones reacting against human autologous cancer cells

We studied the effector mechanism of T cell receptor (TCR) alpha/beta- and gamma/delta-type cytotoxic T lymphocyte (CTL) clones that react with human autologous tumor cells. Treatment of tumor cells with a fungal antibacterial reagent, brefeldin A (BFA), resulted in the inhibition of cytotoxicity of an autologous tumor (HST-2)-specific CD8+ TCR alpha/beta-type CTL, TcHST-2. Other anti-metabolites such as chloroquine, cycloheximide and colchicine did not affect the cytotoxicity. The cell-surface antigen expression, including MHC class I molecules, was not influenced by BFA treatment. Furthermore, BFA did not influence the cytotoxicity of lymphokine-activated killer cells and natural killer cells. Since BFA blocks the transport of peptides from endoplasmic reticulum to the Golgi apparatus, the above data suggest that BFA could affect washing out of the peptide fragments from the MHC class I groove. Consequently, target tumor cells were protected from killing by CTL. Moreover, we obtained a CD4-, 8-, TCR gamma/delta-type (V delta 1+) CTL clone, TcHOT, that reacts against an autologous ovarial carcinoma, HOT. BFA could also inhibit this cytotoxicity, and it is likely that different presenting molecules other than MHC class I proteins participate in the cytotoxicity of this TCR gamma/delta-type CTL. These studies suggest that both TCR alpha/beta- and gamma/delta-type CTL may require antigenic peptides that are most likely derived from the BFA-sensitive, intracellular endogenous target proteins.

Central effects of interleukin-1 on blood pressure, thermogenesis, and the release of vasopressin, ACTH, and atrial natriuretic peptide

To assess the central role of interleukin 1-beta (IL-1 beta) in the release of ACTH, vasopressin (AVP) and atrial natriuretic peptide (ANP) and in the regulation of blood pressure and thermogenesis, 3 ng (0.173 pM) x 100-1 x BW-1 (LIL), 30 ng (1.73 pM) x 100g-1 x BW-1 (MIL), and 150 ng (8.63 pM) x 100g-1 x BW-1 (HIL) of human IL-1 beta dissolved in sterile saline were injected intracerebroventricularly to conscious rats. In the control rats, saline alone (5 microliters) was administered. In three other groups, rats were pretreated with indomethacin, a cyclooxygenase inhibitor, given i.v. (1 mg x 100g-1 x BW-1); medium and high doses of IL-1 beta or its vehicle were given. In the LIL group, IL-1 beta increased blood pressure, body temperature and plasma AVP and ANP without any changes in heart rate (HR) and plasma ACTH. In the MIL group, plasma ACTH was increased, and changes in the other parameters were similar to those in the LIL group. In the HIL group, however, the pressor and thermogenetic responses were attenuated; plasma AVP, ACTH, and ANP were increased; and HR was unchanged. In the control (CON) group, none of these parameters was changed throughout the studies. Indomethacin abolished the AVP and ACTH responses to IL-1 beta, but potentiated the pressor and hypothermic responses and increased plasma ANP. These data suggest that the actions of IL-1 beta on AVP and ACTH release and thermogenesis, but not on blood pressure and the release of ANP, are modulated by the stimulated central production of prostaglandins.

[Double blind controlled study of ubenimex (Bestatin) against squamous cell lung cancer--a multicenter cooperative study]

To investigate effects of the combination of ubenimex, chemotherapy, and radiotherapy against unresectable advanced squamous cell carcinoma of the lung, a placebo controlled double-blind study was performed. Of 365 registered cases, there were 258 cases in the complete radiation group in which the treatment as specified in the protocol (irradiation of 40 Gy or more to the thorax subsequent to chemotherapy) was conducted; the 50% survival time was 449 days and 363 days in the ubenimex group and the placebo group, respectively. A significant (p = 0.0473) prolongation of the survival time was noted in the ubenimex group, and the response rate was 60.9% and 50.0% (p = 0.087). From these results it was confirmed that ubenimex, when used in combination with chemotherapy and radiotherapy, not only enhances the tumor-reducing effect but also prolongs the survival time.

Responses to catecholamines in perfused livers of hypothalamic-lesioned rats

The responses of hepatic glycogenolysis to catecholamines in ventromedial hypothalamus (VMH)-lesioned male rats were examined in perfused livers. Seven days after bilateral electrical lesioning of the VMH, the livers were perfused. Isoproterenol, a beta-agonist, stimulated greater glucose production in VMH-lesioned rats than in controls (32.8 vs. 5.6 mumol glucose.h-1.g liver-1), while responses to phenylephrine, an alpha-agonist, decreased significantly compared with controls (44.4 vs. 69.8 mumol glucose.h-1.g liver-1). There were no significant differences in responses of livers to glucagon and vasopressin between control and VMH-lesioned rats. Adrenodemedullation showed the same effect on beta-responses as lesions in the VMH, but no effect on alpha-responses. Plasma epinephrine levels were not detectable with the high-performance liquid chromatography analysis in VMH-lesioned rats. The periodicity of plasma corticosterone levels was observed in both VMH-lesioned and control rats, although daytime increases in plasma corticosterone were blocked by VMH lesions. These results suggest that the lesions in the VMH cause changes in the levels of adrenergic receptor and that the increase in beta-responses is caused mostly by the reduction of plasma epinephrine.

Role of vagal nerves and atrial natriuretic hormone in vasopressin release and a diuresis under hypertonic volume expansion

To assess whether increases in circulating atrial natriuretic hormone (ANH) in response to the plasma volume expansion, besides the volume receptor-mediated mechanisms, attenuate the arginine vasopressin (AVP) response to increased plasma osmolality and whether changes in plasma AVP and ANH affect renal solute excretion under hypertonic plasma volume expansion, hypertonic saline (0.95 mol/l saline) alone, hypertonic saline with 6% dextran (6D-HS) and hypertonic saline with 9% dextran (9D-HS) were administered into anesthetized dogs. In the control study, 0.15 mol/l NaCl alone was administered. Plasma AVP and ANH and cardiovascular and renal functions were determined. Hypertonic saline and 9D-HS also were administered into the vagotomized and sham operated dogs, and the same parameters were determined. Mean blood pressure and heart rate never changed in all the groups, but central venous pressure and plasma volume increased markedly in 6D-HS and 9D-HS groups. In the control and hypertonic saline groups, central venous pressure increased slightly but plasma volume never changed. Plasma AVP increased in the order of hypertonic saline, 6D-HS and 9D-HS, but plasma ANH increased in reverse order. Vagotomy restored the AVP response to 9D-HS to 75% of its response to hypertonic saline, with a marked rise in plasma ANH. Urine sodium and potassium excretion and urine flow increased in hypertonic saline, 6D-HS and 9D-HS groups, but these increases were comparable among the groups. In the control group, these parameters never changed. These results suggest that the volume receptor-mediated vagal neural and ANH responses to the plasma volume expansion may have an effect on the suppression of the AVP response to osmotic stimuli, and increased plasma ANH release never potentiated the natriuresis under the hypertonic plasma volume expansion.

Is T factor of the TNM staging system a predominant prognostic factor in pathologic stage I non-small-cell lung cancer ? A multivariate prognostic factor analysis of 151 patients

We attempted to clarify whether the T factor of the TNM staging system should be viewed as a predominant prognostic factor in patients with pathologic stage I non-small-cell lung cancer when analyzed together with various histopathologic factors and deoxyribonucleic acid ploidy pattern of tumors. We studied 151 patients who were in this stage. Histopathologic factors used in the analysis were as follows: histologic cell type (squamous or nonsquamous cell carcinoma), grade of differentiation, and tumor invasion of visceral pleura and vessels. Deoxyribonucleic acid ploidy pattern of tumors was analyzed by flow cytometry, and the tumors were classified as diploid or aneuploid tumors. Significant prognostic factors (p < 0.05) that were demonstrated by univariate analysis of survival curves were as follows: (1) T1 versus T2; (2) well versus moderately or poorly differentiated tumor; (3) the absence versus presence of tumor exposed on pleura, (4) artery invasion, (5) lymphatic vessel invasion; and (6) diploid versus aneuploid tumor. Multivariate prognostic factor analysis showed the grade of differentiation and deoxyribonucleic acid ploidy pattern to be predominant prognostic factors. The T2 tumor group had significantly more cases with tumor invasion of lymphatic vessels that did the T1 tumor group and included 18 cases with tumor exposed on pleura. When these two factors were excluded from multivariate analysis, the T factor was marginally significant (p = 0.08). These observations suggest that the T factor is not necessarily a predominant prognostic factor in pathologic stage I non-small-cell lung cancer.

Polymorphism of crystals of Salmonella minnesota Re and Ra lipopolysaccharides

Salmonella minnesota Re and Ra lipopolysaccharides (LPSs) formed three-dimensional crystals when they were precipitated by the addition of 2 volumes of 95% ethanol containing 375 mM MgCl2 and incubated in 70% ethanol containing 250 mM MgCl2 at 4 C. Besides typical shapes of crystals, hexagonal plates and solid columns, which were already reported (J. Bacteriol. 172: 1516-1528 (1990)), the LPSs thus treated formed crystals possessing various shapes such as square or rectangular plate, lozenge plate, discoid, and truncated hexangular pyramid forms. Electron diffraction patterns from all these crystals except square or rectangular plate crystals obtained by electron irradiation from the direction perpendicular to the basal plane were essentially the same as those from hexagonal plate crystals, indicating that they consist of hexagonal lattices with the lattice constant of 4.62 A. From these results as well as the results of electron microscopic observations of these crystals, it was concluded that all these crystals except square or rectangular plate crystals are composed of hexagonal plate sheets as the basic structural units. Square or rectangular crystals were assumed to correspond to the (1011) planes of solid hexagonal column crystals.

Detailed genetic and physical map of the 3p chromosome region surrounding the familial renal cell carcinoma chromosome translocation, t(3;8)(p14.2;q24.1)

Extensive studies of loss of heterozygosity of 3p markers in renal cell carcinomas (RCCs) have established that there are at least three regions critical in kidney tumorigenesis, one most likely coincident with the von Hippel-Lindau gene at 3p25.3, one in 3p21 which may also be critical in small cell lung carcinomas, and one in 3p13-p14.2, a region which includes the 3p chromosome translocation break of familial RCC with the t(3;8)(p14.2;q24.1) translocation. A panel of rodent-human hybrids carrying portions of 3p, including a hybrid carrying the derivative 8 (der(8)(8pter-->8q24.1::3p14.2-->3pter)) from the RCC family, have been characterized using 3p anchor probes and cytogenetic methods. This 3p panel was then used to map a large number of genetically mapped probes into seven physical intervals between 3p12 and 3pter defined by the hybrid panel. Markers have been physically, and some genetically, placed relative to the t(3;8) break, such that positional cloning of the break is feasible.

Structures of asparagine linked oligosaccharides of immunoglobulins (IgY) isolated from egg-yolk of Japanese quail

Structures of the Asn linked oligosaccharides of quail egg-yolk immunoglobulin (IgY) were determined in this study. Asn linked oligosaccharides were cleaved from IgY by hydrazinolysis and labelled with p-aminobenzoic acid ethyl ester (ABEE) after N-acetylation. The ABEE labelled oligosaccharides were then fractionated by a combination of Concanavalin A-agarose column chromatography and anion exchange, normal phase and reversed phase HPLC before their structures were determined by sequential exoglycosidase digestion, methylation analysis, HPLC, and 500 MHz 1H-NMR spectroscopy. Quail IgY contained only neutral oligosaccharides of the following categories: the glucosylated oligomannose type (0.6% Glc alpha 1-3Glc alpha 1-3Man9GlcNAc2; 35.6%, Glc alpha 1-3Man7-9GlcNAc2). oligomannose type (15.0%, with the structure Man5-9GlcNAc2) and biantennary complex type with core structures of -Man alpha 1-3(-Man alpha 1-6)Man beta 1-4GlcNAc beta 1-4GlcNAc (9.9%), -Man alpha 1-3 (GlcNAc beta 1-4)(-Man alpha 1-6)Man beta 1-4GlcNAc beta 1-4GlcNAc (25.1%) and -Man alpha 1-3(GlcNAc beta 1-4)(-Man alpha 1-6)Man beta 1-4GlcNAc beta 1-4(Fuc alpha 1-6)GlcNAc (11.4%). Although never found in mammalian proteins, glucosylated oligosaccharides (Glc1Man7-9GlcNAc2) have been located previously in hen IgY.

Hypotonic cisplatin treatment for carcinomatous pleuritis found at thoracotomy in patients with lung cancer. In vitro experiments and preliminary clinical results

We have developed an intraoperative intrapleural treatment with the use of distilled water combined with cisplatin for carcinomatous pleuritis found at thoracotomy in patients with non-small-cell lung cancer. In the in vitro experiment, three different cell lines were used as a model of malignant pleural effusion. Cell growth was examined after a 3-day culture, which was preceded by exposure of the cells to cisplatin in either phosphate-buffered saline solution or distilled water for 1/2 to 5 minutes. The growth inhibition of tumor cells after hypotonic cisplatin treatment was significantly greater than after treatment with saline solution and cisplatin. Tumor that was obtained by resection of non-small-cell lung cancer was used as a model to demonstrate decreased viability of the tumor after exposure to hypotonic cisplatin. The viability of the tumor in a 6-day culture, preceded by exposure to hypotonic cisplatin (50 micrograms/ml) for 10 minutes, was markedly decreased. Intraoperative intrapleural hypotonic cisplatin was instilled in seven patients with pleural carcinomatosis without side effects and with control of pleural dissemination and pleural effusion for 6 to 29 months.

[Dietary fiber intake and intake patterns among the general population in Aomori, calculated using modified Southgate and Prosky methods]

Based on the result of the Aomori Nutrition Survey, we have calculated daily dietary fiber (DF) intake using modified Southgate and Prosky methods. Result obtained were as follows: DF intake in Aomori was 23.7 +/- 8.4g by the modified Southgate method, and 22.2 +/- 8.5g by the modified Prosky method. As for supply sources of DF, 32.3% was from grains; 22.7%, vegetables; 15.6%, beans; and 7.8%, fruits calculated by the modified Southgate method, and 31.3%, vegetables; 19.0%, grains; 18.0%, beans; and 11.6%, fruits by the modified Prosky method. As to types of DF, intake of hemicellulose was 11.5 +/- 4.2g, cellulose 7.8 +/- 3.0g and lignin 4.4 +/- 2.3g. In the group with DF intake below 10.0g, DF came mainly from grains and fruits, while the group with DF intake above 30.0g took DF from various foods.

[The significance of HPV 16, 18 infection and the DNA ploidy associated with the progression of uterine cervical dysplasia]

We investigated the significance of HPV 16, 18 infection and DNA ploidy in the progression to malignancy of uterine cervical dysplasia. Formalin-fixed, paraffin-embedded surgical and biopsy specimens obtained from 59 women were examined. The 59 women were classified into two groups: one of progression cases and the other regression cases. Polymerase chain reaction (PCR) and dot blot hybridization (DBH) were used for the detection of HPV 16/18 DNA, while flow cytometry was used for the analysis of the relative cellular DNA content in samples prepared by Hedley's method. Eight out of 29 progression cases (27.6%) and 3 out of 30 regression cases (10.0%) exhibited HPV 16/18 DNA, whereas 14 out of 29 progression cases (48.3%) and 2 out of 30 regression cases (6.7%) involved a DNA aneuploid population, representing a DNA index in the former above 1.5 and in the latter below 1.5. The proportion of cases having a population of DNA aneuploid together with the presence of HPV 16/18 DNA was 20.7% (6/29) in the progression group and 0% (0/30) in the regression group. These results indicate that the DNA aneuploid population coupled with simultaneous HPV 16, 18 infection may be used as a marker for progression in uterine cervical dysplasia.

Establishment and characterization of a monoclonal antibody recognizing the Dewar isomers of (6-4)photoproducts

We established a monoclonal antibody (DEM-1) that recognizes UV-induced DNA damage other than cyclobutane pyrimidine dimers or (6-4)photoproducts. The binding of DEM-1 antibody to 254 nm UV-irradiated DNA increased with subsequent exposure to UV wavelengths longer than 310 nm, whereas that of the 64M-2 antibody specific for the (6-4)photoproduct decreased with this treatment. Furthermore, the increase in DEM-1 binding was inhibited by the presence of the 64M-2 antibody during the exposure. We concluded that the DEM-1 antibody specifically recognized the Dewar photoproduct, which is the isomeric form of the (6-4)photoproduct. The DEM-1 antibody, however, also bound to DNA irradiated with high fluences of 254 nm UV, suggesting that 254 nm UV could induce Dewar photoproducts without subsequent exposure to longer wavelengths of UV. Furthermore, an action spectral study demonstrated that 254 nm was the most efficient wavelength for Dewar photoproduct induction in the region from 254 to 365 nm, as well as cyclobutane dimers and (6-4)photoproducts, although the action spectrum values in the UV-B region were significantly higher compared with those for cyclobutane dimer and (6-4)photoproduct induction.

Plasmid-mediated AmpC-type beta-lactamase isolated from Klebsiella pneumoniae confers resistance to broad-spectrum beta-lactams, including moxalactam

Klebsiella pneumoniae NU2936 was isolated from a patient and was found to produce a plasmid-encoded beta-lactamase (MOX-1) which conferred resistance to broad spectrum beta-lactams, including moxalactam, flomoxef, ceftizoxime, cefotaxime, and ceftazidime. Resistance could be transferred from K. pneumoniae NU2936 to Escherichia coli CSH2 by conjugation with a transfer frequency of 5 x 10(-7). The structural gene of MOX-1 (blaMOX-1) was cloned and expressed in E. coli HB101. The MIC of moxalactam for E. coli HB101 producing MOX-1 was > 512 micrograms/ml. The apparent molecular mass and pI of this enzyme were calculated to be 38 kDa and 8.9, respectively. Hg2+ and Cu2+ failed to block enzyme activity, and the presence of EDTA in the reaction buffer did not reduce the enzyme activity. However, clavulanate and cloxacillin, serine beta-lactamase inhibitors, inhibited the enzyme activity competitively (Kis = 5.60 and 0.35 microM, respectively). The kinetic study of MOX-1 suggested that it effectively hydrolyzed broad-spectrum beta-lactams. A hybridization study confirmed that blaMOX-1 is encoded on a large resident plasmid (pRMOX1; 180 kb) of strain NU2936. By deletion analysis, the functional region was localized within a 1.2-kb region of the plasmid. By amino acid sequencing, 18 of 33 amino acid residues at the N terminus of MOX-1 were found to be identical to those of Pseudomonas aeruginosa AmpC. These findings suggest that MOX-1 is a plasmid-mediated AmpC-type beta-lactamase that provides enteric bacteria resistance to broad-spectrum beta-lactams, including moxalactam.

Comparison of the lateral diffusion constant of hepatocyte membrane proteins in two wild mouse strains of considerably different longevity: FRAP studies on liver smears

The liver cells of male and female wild mice (Peromyscus leucopus and Mus musculus) have been studied in young, adult, and old age groups. Because P. leucopus displays a life expectancy of 7-8 years, the age groups of this strain were from 5.5 to 68 months. M. musculus survives only to about 2.5 years; therefore, the age groups of this strain ranged from 6 to 27 months. Protein lateral diffusion in hepatocyte membranes was measured by means of fluorescence recovery after photobleaching (FRAP) in liver smears. The peroxide-induced autofluorescence was utilized as a fluorescent label, which in H2O2 treated liver smears is caused by the oxidation of riboflavin bound uniformly to all proteins of the cell membrane. This way the average lateral diffusion constant (D) and the fractional recovery of those proteins can be measured. In both males and females of both strains D displayed a negative linear age correlation. Intraspecies sex differences were small and statistically insignificant. However, interspecies comparisons of males or females resulted in a strongly significant difference: although the intercept points of the regression lines describing D were identical in both strains (3.1 x 10(-10) cm2/sec), the decay of D with aging was about 2.5 times faster in the short-living M. musculus than in the long-living P. leucopus. By the end of life expectancy, both strains reached practically identical values (about 1.9 x 10(-10) cm2/sec). The results lend further support to the membrane hypothesis of aging.

Defenestration of the sinusoidal endothelial cell in a rat model of cirrhosis

We characterized the structural and immunohistological changes of sinusoidal endothelial cells that occur during cirrhosis in rats made cirrhotic with thioacetamide. Thioacetamide (200 mg/kg body wt) was injected intraperitoneally three times a week into male Wistar rats. Two, 4, 6 and 12 wk later, rat livers were observed under transmission and scanning electron microscopy and regular microscopy and immunostained with laminin and von Willebrand factor (factor VIII-related antigen) antibodies. The diameters and numbers of sinusoidal endothelial fenestrations did not change significantly after 2 wk in the thioacetamide-treated rats; however, they decreased within 4 wk after thioacetamide treatment. A basement membranelike structure in Disse's space was noted 6 wk after thioacetamide treatment. Laminin was detected in Disse's space after 4 wk. In vitro, in cultured sinusoidal endothelial cells, the diameter of sinusoidal endothelial fenestrations was significantly lower at 6 wk in thioacetamide-treated rats. von Willebrand factor was detected in the cytoplasm as granular fluorescence after 6 wk of thioacetamide treatment. These results suggest that as fibrosis develops in cirrhosis, the structural and immunohistochemical characteristics of sinusoidal endothelial cells change.