In vivo development of decreased susceptibility to vancomycin in clinical isolates of methicillin-resistant Staphylococcus aureus

To investigate the possibility of in vivo development of decreased vancomycin susceptibility, the vancomycin susceptibilities of 12 methicillin-resistant Staphylococcus aureus (MRSA) isolates serially recovered from six patients with vancomycin therapy were tested by standard MIC determination method and population analysis. While all of the MRSA isolates were susceptible to vancomycin (MICs, 1-2 microg/ml) by standard method, population analysis showed the upward shifts indicating decreased vancomycin susceptibility among serial isolates from two patients. These bacteria with decreased vancomycin susceptibility could be selected by using vancomycin selection of pre-therapy isolates under laboratory conditions. Furthermore, the reversion phenomenon of decreased vancomycin susceptibility was confirmed after 20 serial passages of the post-therapy isolates on drug-free agar. These data suggest that in vivo isolates may develop decreased vancomycin susceptibility that is not of such magnitude to cross a breakpoint threshold. This resistance may be unstable, and appears to result from a selective or inducible process that occurs in MRSA clinical strains during vancomycin therapy.

Cytological changes induced by intravesical bacillus Calmette-Guérin therapy for superficial bladder cancer

To evaluate cytological changes of urothelial cells with intravesical instillation therapy of the bacillus Calmette-Guérin (BCG), cytological specimens of voided urine from patients with superficial bladder cancer (pTa and pT1) treated with intravesical BCG therapy were examined. The following three groups of patients who had no evidence of recurrence more than 2 years after the treatment were studied: groups 1 and 2, patients who were treated with BCG (n = 22) and epirubicin, a derivative of doxorubicin (n = 22), respectively, for prophylaxis of intravesical recurrence after transurethral resection (TUR); and group 3, patients receiving no intravesical therapy after TUR (n = 12). Sixteen cytological characteristics were studied before and after the treatment in each group. In group 1 patients translucent nuclei and prominent nucleoli, vacuolization of cytoplasm, and eosinophilic cytoplasmic inclusions were frequently observed in urothelial cells as well as an increase in granulocytes, especially within 3 months after BCG instillation therapy. In group 2 patients an increased nuclear/cytoplasmic ratio, hyperchromatic nuclei and prominent nucleoli of urothelial cells were transiently found within 1-2 months after intravesical epirubicin therapy. In group 3, translucent nuclei and prominent nucleoli of urothelial cells were found within 1-2 months after TUR. In conclusion, cytological changes induced by BCG therapy are nonspecific and reactive in nature, different from those due to chemotherapeutic agents and distinguishable from malignant changes of urothelial cells.

Adjuvant chemotherapy including cisplatin in endometrial carcinoma

To determine the outcome of patients with endometrial endometrioid adenocarcinoma following adjuvant chemotherapy, CAP (cyclophosphamide, pirarubicin and cisplatin) and EP (etoposide and cisplatin) were assigned at random to patients with Ic or more advanced stage carcinoma, and their efficacy was compared. These patients were treated by the Tokai Endometrial Cancer Study Group (Nagoya University and related institutions) between January 1992 and June 1996. The 5-year survival rate was 88.4% in the CAP group and 95.1% in the EP group; the difference between the two groups was not significant (p = 0.3496). The disease-free survival rate was 80. 3% in the CAP group and 84.8% in the EP group (nonsignificant: p = 0. 4533). However, the 5-year disease-free survival rates were 95.1 and 71.0% in patients with preoperative CA125 levels <35 and > or =35 IU/ml, and there was a significant difference in disease-free survival curves (p<0.05). A significant difference was also observed in disease-free survival curves between patients with and without pelvic lymph node metastasis (5- year disease-free survival rate: 68.8 and 88.2% in patients with and without pelvic lymph node metastasis, respectively, p<0.05). Multivariate analysis of disease- free survival showed that the preoperative CA125 level, and pelvic lymph node metastasis were significant risk factors for recurrence. In conclusion, the EP chemotherapy had no significant advantage in terms of survival and disease-free survival compared to CAP, although these rates were superior in the EP group compared to the CAP group.

Phenotypic variation of familial hypertrophic cardiomyopathy caused by the Phe(110)-->Ile mutation in cardiac troponin T

Mutation of the cardiac troponin T (cTnT) gene is a genetic determinant of familial hypertrophic cardiomyopathy (HCM). A Japanese family of 14 individuals, including 6 with HCM, was subjected to genetic and clinical assessment. Five exons of the cTnT gene were sequenced in all family members. A heterozygous or homozygous T(340)-->A (Phe(110)-->Ile) mutation in exon 9 of the cTnT gene was detected in 11 subjects. Morphological and functional evaluation of the left and right ventricles by echocardiography revealed that 4 of 9 individuals heterozygous for the mutant allele exhibited HCM with moderate cardiac hypertrophy. Cardiac hypertrophy and other clinical features in the 2 subjects homozygous for the mutation were more severe than were those in heterozygous individuals with HCM. Thus, the clinical features of HCM due to the Phe(110)-->Ile mutation in the cTnT gene appear to be modified by a gene dosage effect.

Pulmonary microcystic hamartoma in an adult dog

Microcystic hamartoma was detected as a tumorlike mass in the left caudal lung lobe of a 12-year-old mixed-breed dog. Histologically, the mass was characterized by microcysts of various sizes that mimicked alveoli and were surrounded by thin fibrous septal tissue. However, unlike the adjacent lung parenchyma, bronchial or bronchiolar trees were absent, and the septal vascular channels were extremely underdeveloped. Immunohistochemically, the cells lining the microcysts were consistently positive for cytokeratin but not for vimentin, whereas the septal fibroblast-like cells were negative for cytokeratin and positive for vimentin. Electron microscopy confirmed that the microcysts were lined with a layer of type I and type II mature pneumocytes. This is the first description of the detailed morphologic features of microcystic hamartoma.

Glandular malignant peripheral nerve sheath tumor: an unusual case showing histologically malignant glands

In this report, we describe a highly unusual case of glandular malignant peripheral nerve sheath tumor presenting as a neck mass in a previously healthy 29-year-old man. Grossly, the tumor was found to arise from a swollen peripheral nerve trunk. The tumor was largely composed of spindle cells that demonstrated marked nuclear pleomorphism and numerous abnormal mitotic figures. In addition, histologically malignant glandular structures lined by simple nonciliated columnar cells with goblet cells were found clustered in the center of the tumor. Examination of the swollen peripheral nerve trunk revealed the presence of a plexiform neurofibroma. The spindle cells were positive for S100. The glands were negative for S100 but positive for keratin, epithelial membrane antigen, and neuroendocrine markers (somatostatin, chromogranin, Leu-7, and calcitonin). This patient was subsequently diagnosed as having von Recklinghausen disease and died of tumor metastasis to the lungs 34 months after the presentation. To our knowledge, only 3 similar cases have been previously described in the literature.

[A consideration on discrepancy of results obtained between commercial CRP measurement kits]

We investigated the frequency of the occurrence of discrepancies using various patients' sera between several commercial C reactive protein(CRP) kits with turbidimetric immunoassay, and the elucidation of the mechanism of the non-specific reaction, also investigated methods of minimizing false results in some procedures. CRP was measured in 79 patients' sera containing monoclonal immunoglobulins [Multiple Myeloma: 45 patients' sera(IgG type, 37; IgA type, 7; BJP type, 1); Waldenström's disease: 8; Benign M proteinemia: 26], 70 patients' sera with polyclonal high gamma-globulinemia (> 2.0 g/dl) and 91 patients' sera with positive rheumatoid factor. Two different patients' sera, one(chronic hepatitis C) with Waldenström's disease and the other(purpura) with polyclonal high gamma-globulinemia, showed marked discrepancies. We found these discrepancies were induced by milky turbidity produced by non-specific reaction between high molecular weight components(cryoglobulin composed from IgM-IgG in the Waldenström case and immune complex in the polyclonal high gamma-globulinemia case), and the buffer solution contained polyethylene glycol(PEG) as a catalyst. The discrepancy was minimized by the following procedures: (a) decreasing the PEG concentration, (b) increasing pH of the buffer solution, (c) using a small volume of the secondary reagent(R2), and (d) using rabbit anti-human CRP serum instead of goat serum.

Elucidation of vascular structure of molar villi in complete hydatidiform mole by CD-34 antibody

Vasculature was examined immunohistochemically in the villous stroma in 22 cases of complete hydatidiform mole (CHM). Only antibody CD-34 was able to detect the vasculature. Serial thin and thick sections and squashed preparations of molar villi were stained by CD-34, and sequential photographs of the vasculature were taken and projected on paper, and the vasculature was described and reconstructed. In the stroma of almost all molar villi examined, vessels were found, but their density and structure varied greatly in each molar villus even in the same CHM, and the vessels were irregular in diameter. In fully distended molar villi the vessels often became narrow, continuing like a broken line but eventually vanishing. Generally the density of the vessels was inversely proportional to the grade of the swelling of villi. The vessels sometimes passed through two adjacent molar vesicles. No significant differences in vasculature were found in molar villi at different gestational ages.

Total and pancreatic amylase measured with 2-chloro-4-nitrophenyl-4-O-beta-D-galactopyranosylmaltoside

BACKGROUND

: Many different methods have been used to assay amylase activity, using nitrophenylated oligosaccharides as substrate; however, the hydrolysis steps in these methods are complex.

METHODS

: We developed a new continuously monitoring assay for amylase activity in biological fluids, using 2-chloro-4-nitrophenyl-4-O-beta-D-galactopyranosylmaltoside (GalG2CNP) as the substrate; this assay was used with anti-human salivary amylase monoclonal antibodies for specific determination of the pancreatic isoenzyme. Amylase converted GalG2CNP into beta-D-galactopyranosylmaltose and 2-chloro-4-nitrophenol, which was measured at 405 nm.

RESULTS

: GalG2CNP was cleaved between 2-chloro-4-nitrophenol and beta-D-galactopyranosylmaltose and did not undergo transfer reactions. The within-assay CVs (n = 20) for total amylase (T-AMY) and pancreatic amylase (P-AMY) were 0.6-1.6% and 0.5-2.5%, respectively; and day-to-day CVs (n = 10) for T-AMY and P-AMY were 0.8-3.7% and 0.6-4.1%, respectively. T-AMY and P-AMY activities in serum or urine obtained by the proposed method correlated well with those determined by the 2-chloro-4-nitrophenyl 4-O-beta-D-galactopyranosyl-beta-maltotetraoside method or the modified IFCC method.

CONCLUSIONS

: This novel assay for T-AMY and P-AMY measures both activities stoichiometrically, directly, and easily, and may be suitable for routine procedures.

Association of a T29-->C polymorphism of the transforming growth factor-beta1 gene with genetic susceptibility to myocardial infarction in Japanese

BACKGROUND

Transforming growth factor-beta (TGF-beta) is an important regulator of vascular remodeling and is involved in the pathogenesis of atherosclerosis. A T-->C transition at nucleotide 29 of the TGF-beta1 gene results in a Leu-->Pro substitution at amino acid 10 of the signal peptide. We have now examined a possible association of TGF-beta1 genotype with myocardial infarction (MI) in a Japanese population.

METHODS AND RESULTS

TGF-beta1 genotype was determined in 315 Japanese patients (234 men and 81 women) with MI and 591 control subjects (289 men and 302 women). We found that age, body mass index, and incidence of habitual smoking, hypertension, diabetes mellitus, and hypercholesterolemia did not differ between the 2 groups for either men or women. Multivariable logistic regression analysis, however, demonstrated the frequency of the T allele to be significantly higher in male subjects with MI than in controls (TT + TC versus CC; P<0.0001, odds ratio 3.5, 95% CI 2.0 to 6.3). In contrast, the T allele was not associated with the prevalence of MI in women. In both male MI patients and controls, the serum concentration of TGF-beta1 was significantly higher in individuals with the CC genotype than in subjects with the TT or TC genotype.

CONCLUSIONS

Findings suggest that the T allele at nucleotide 29 in the TGF-beta1 gene is a risk factor for genetic susceptibility to MI, at least in middle-aged Japanese men.

Persistent activation of phosphatidylinositol 3-kinase causes insulin resistance due to accelerated insulin-induced insulin receptor substrate-1 degradation in 3T3-L1 adipocytes

Recently, we have reported that the overexpression of a membrane-targeted phosphatidylinositol (PI) 3-kinase (p110CAAX) stimulated p70S6 kinase, Akt, glucose transport, and Ras activation in the absence of insulin but inhibited insulin-stimulated glycogen synthase activation and MAP kinase phosphorylation in 3T3-L1 adipocytes. To investigate the mechanism of p110CAAX-induced cellular insulin resistance, we have now studied the effect of p110CAAX on insulin receptor substrate (IRS)-1 protein. Overexpression of p110CAAX alone decreased IRS-1 protein levels to 63+/-10% of control values. Insulin treatment led to an IRS-1 gel mobility shift (most likely caused by serine/threonine phosphorylation), with subsequent IRS-1 degradation. Moreover, insulin-induced IRS-1 degradation was enhanced by expression of p110CAAX (61+/-16% vs. 13+/-15% at 20 min, and 80+/-8% vs. 41+/-12% at 60 min, after insulin stimulation with or without p110CAAX expression, respectively). In accordance with the decreased IRS-1 protein, the insulin-stimulated association between IRS-1 and the p85 subunit of PI 3-kinase was also decreased in the p110CAAX-expressing cells, and IRS-1-associated PI 3-kinase activity was decreased despite the fact that total PI 3-kinase activity was increased. Five hours of wortmannin pretreatment inhibited both serine/threonine phosphorylation and degradation of IRS-1 protein. These results indicate that insulin treatment leads to serine/threonine phosphorylation of IRS-1, with subsequent IRS-1 degradation, through a PI 3-kinase-sensitive mechanism. Consistent with this, activated PI 3-kinase phosphorylates IRS-1 on serine/threonine residues, leading to IRS- 1 degradation. The similar finding was observed in IRS-2 as well as IRS-1. These results may also explain the cellular insulin-resistant state induced by chronic p110CAAX expression.

Aminopeptidase A expression in cervical neoplasia and its relationship to neoplastic transformation and progression

Aminopeptidase A (AP-A) is a cell surface metallopeptidase which specifically cleaves the amino-terminal acidic residue from peptide substrates such as angiotensin II. AP-A is identical to the differentiation-related antigen, murine BP-1 or human kidney gp160, and is involved in regulating cell differentiation and/or neoplastic transformation of certain normal and transformed cells. We examined expression of AP-A in premalignant and malignant lesions of the uterine cervix, and investigated whether its expression was related to disease progression and neoplastic transformation. Formalin-fixed, paraffin-embedded tissue sections including 14 cervical intraepithelial neoplasms (CIN) and 23 invasive squamous cell carcinomas (SCC) were immunohistochemically evaluated. AP-A was localized in the basal cell layer in normal squamous epithelium. In CIN, AP-A expression was found on dysplastic cells, and increased with the severity of the precancerous lesions. In invasive cancer, 18 of 19 non-keratinizing-type SCCs and none of 4 keratinizing-type SCCs expressed AP-A. In addition, AP-A immunoreactivity was significantly correlated with proliferating cell nuclear antigen expression in both CIN and SCC cases. Furthermore, angiotensin II type 1 receptor was present in all AP-A-positive SCCs. These results indicate that AP-A is upregulated as the lesion progresses toward carcinoma in the cervical epithelium, and suggest that AP-A may play a regulatory role in neoplastic transformation and disease progression in cervical neoplasms and may serve as a potential tumor marker during cervical neoplasia development.

Association of SYT-SSX fusion types with proliferative activity and prognosis in synovial sarcoma

The t(X;18)(p11.2;q11.2) translocation commonly found in synovial sarcoma (SS) results in the fusion of the SYT gene on chromosome 18 to either of two closely related genes, SSX1 and SSX2, on chromosome X. It has been suggested that patients who have SS bearing SYT-SSX1 fusion have worse prognosis than those bearing SYT-SSX2 fusion. However, little is known about the biologic basis or the relationship with the histopathologic risk factors in regard to the different fusion types. We analyzed 19 cases of SS with no metastasis at diagnosis. These tumors were classified by reverse transcription-polymerase chain reaction to SYT-SSX1 and SYT-SSX2 types. The expression of Ki-67, p27, p53, and bcl-2 and various clinicopathologic parameters including mitotic rate were compared between the two fusion types. The SYT-SSX1 type fusion was associated with high Ki-67 expression (P = .011) and high mitotic rate (P = .070). No significant differences were found between the two types as to the expression of p27, p53, and bcl-2 and other clinicopathologic parameters. The survival analysis showed that SYT-SSX1-type fusion, high Ki-67 expression, and high mitotic rate correlated with shorter metastasis-free survival. These data suggested that SYT-SSX fusion type is associated with tumor cell proliferative activity and prognosis of patients who have SS.

Age related differences in electroencephalographic and cardiac arousal at the termination of sleep apnea/hypopnea

OBJECTIVE

The purpose of the present study was to determine whether electroencephalographic (EEG) and cardiac arousal, i.e. heart rate elevation at the termination of apnea/hypopnea are related to aging.

METHODS

The subjects were 13 middle-aged (40-60 years of age, 47.8+/-5.35 years) and 10 elderly (>60 years of age, 69.8+/-5.31 years) male patients with obstructive sleep apnea syndrome. We evaluated the number of apneas per an hour of sleep (apnea index: AI), the number of hypopneas per an hour of sleep (hypopnea index: HI), the summation of HI and AI (apnea/hypopnea index: AHI), sleep stage, the amount of time during which nocturnal oxygen saturation was decreased below 90% (oxygen desaturation time: ODT), and EEG and cardiac arousal at the termination of apnea/hypopnea using polysomnography with pulse oximetry.

RESULTS

There was no significant difference in AHI, duration of apnea/hypopnea, and sleep stage distribution between the two groups. However, the ratio of apnea/hypopnea with EEG and cardiac arousal was significantly higher in middle-aged than in elderly patients. The ratio of HI to AHI was significantly lower in middle-aged than in elderly patients. In middle-aged patients, EEG and cardiac arousal were significantly correlated with AI, AHI, and ODT, whereas, in elderly patients, these parameters were not similarly correlated.

CONCLUSION

Our findings suggest that the differences in EEG and cardiac arousal, and the pattern of sleep-disordered breathing (SDB) between middle-aged and elderly patients with SDB might be a physiological phenomenon of aging.

The tumor suppressor PTEN negatively regulates insulin signaling in 3T3-L1 adipocytes

PTEN is a tumor suppressor with sequence homology to protein-tyrosine phosphatases and the cytoskeleton protein tensin. PTEN is capable of dephosphorylating phosphatidylinositol 3,4, 5-trisphosphate in vitro and down-regulating its levels in insulin-stimulated 293 cells. To study the role of PTEN in insulin signaling, we overexpressed PTEN in 3T3-L1 adipocytes approximately 30-fold above uninfected or control virus (green fluorescent protein)-infected cells, using an adenovirus gene transfer system. PTEN overexpression inhibited insulin-induced 2-deoxy-glucose uptake by 36%, GLUT4 translocation by 35%, and membrane ruffling by 50%, all of which are phosphatidylinositol 3-kinase-dependent processes, compared with uninfected cells or cells infected with control virus. Microinjection of an anti-PTEN antibody increased basal and insulin stimulated GLUT4 translocation, suggesting that inhibition of endogenous PTEN function led to an increase in intracellular phosphatidylinositol 3,4,5-trisphosphate levels, which stimulates GLUT4 translocation. Further, insulin-induced phosphorylation of downstream targets Akt and p70S6 kinase were also inhibited significantly by overexpression of PTEN, whereas tyrosine phosphorylation of the insulin receptor and IRS-1 or the phosphorylation of mitogen-activated protein kinase were not affected, suggesting that the Ras/mitogen-activated protein kinase pathway remains fully functional. Thus, we conclude that PTEN may regulate phosphatidylinositol 3-kinase-dependent insulin signaling pathways in 3T3-L1 adipocytes.

Safety of pyrethroid-treated mosquito nets

The use of insecticide treated nets (ITNs) for personal protection against malaria vector Anopheles mosquitoes (Diptera: Culicidae) has become popular during the past decade. With the precautions outlined in this paper, field use of pyrethroids--at concentrations recommended for treatment of mosquito nets--poses little or no hazard to people treating the nets or to users of the treated nets. With frequent exposure to low concentrations of pyrethroids, the risk of toxicity of any kind is remote. Pyrethroids entering the systemic circulation are rapidly metabolized to much less toxic metabolites. Toxicologically, pyrethroids have a useful characteristic--the production of skin paraesthesia--which gives an early indication of exposure. This reversible symptom of exposure is due to transient stimulation of peripheral sensory nerves and not a toxic effect. In the retail market, for home use, the provision of proper packaging and labelling, with clear instructions on safe and effective use of the product are most important. Because many domestic users of pyrethroid 'home treatment kits' for ITNs may not be fully literate, it is essential that 'instructions for use' should be portrayed via pictograms with supporting text in appropriate local language(s).

Methionine-independent initiation of translation in the capsid protein of an insect RNA virus

Protein synthesis is believed to be initiated with the amino acid methionine because the AUG translation initiation codon of mRNAs is recognized by the anticodon of initiator methionine transfer RNA. A group of positive-stranded RNA viruses of insects, however, lacks an AUG translation initiation codon for their capsid protein gene, which is located at the downstream part of the genome. The capsid protein of one of these viruses, Plautia stali intestine virus, is synthesized by internal ribosome entry site-mediated translation. Here we report that methionine is not the initiating amino acid in the translation of the capsid protein in this virus. Its translation is initiated with glutamine encoded by a CAA codon that is the first codon of the capsid-coding region. The nucleotide sequence immediately upstream of the capsid-coding region interacts with a loop segment in the stem-loop structure located 15-43 nt upstream of the 5' end of the capsid-coding region. The pseudoknot structure formed by this base pair interaction is essential for translation of the capsid protein. This mechanism for translation initiation differs from the conventional one in that the initiation step controlled by the initiator methionine transfer RNA is not necessary.

Expression of aminopeptidase A in human gestational choriocarcinoma cell lines and tissues

Aminopeptidase A (AP-A), a cell-surface metallopeptidase hydrolyzing peptide with N-terminal acidic residues, has been proved to be identical to the B cell differentiation antigen BP-1 and to the kidney differentiation antigen gp160, suggesting recognition of AP-A as a differentiation-related marker on certain normal and transformed cells. AP-A has also been purified from human placenta and been shown to be localized in the trophoblasts. In the present study, we examined the expression and enzymatic activity of AP-A in human gestational choriocarcinoma, a neoplastic transformant from trophoblasts which comprises a heterogenous population of trophoblastic cells in different stages of differentiation. Flow cytometry and immunoblot analysis demonstrated that AP-A was expressed in five choriocarcinoma cell lines which were secreting low or moderate levels of human chorionic gonadotropin (hCG), while two high hCG-secreting cell lines lacked AP-A expression. The AP-A enzymatic activity correlated with cell-surface levels of AP-A and was abrogated by amastatin, an inhibitor of AP-A. Immunohistochemical analysis revealed that AP-A was present in seven of eight choriocarcinoma tissues and was localized on the cell membrane of cytotrophoblastic choriocarcinoma cells, but not on cells with syncytiotrophoblast-like features. These results demonstrate that AP-A is expressed on most choriocarcinomas and its expression is restricted to low hCG-secreting, cytotrophoblastic cells and down-regulated as a function of cell differentiation, suggesting an involvement of AP-A in the differentiation/maturation process of neoplastic trophoblasts.

Determining the nucleotide sequence and capsid-coding region of himetobi P virus: a member of a novel group of RNA viruses that infect insects

We determined the complete genome sequence of Himetobi P virus (HiPV), an insect picorna-like virus, which was isolated from the small brown planthopper, Laodelphax striatellus. The genome of HiPV consists of 9,275 nucleotides excluding the poly (A) tail, and contains two large open reading frames (ORFs), which were separated by a 176-nucleotide noncoding region. The deduced amino acid sequence of the first ORF contains core motifs of picornaviral helicase, protease, and RNA-dependent RNA polymerase. The capsid protein-coding region was mapped onto the second ORF by determining the N-terminal amino acid sequences of the capsid proteins. Subgenomic RNA for the capsid protein gene was not detected in the infected tissue. The capsid protein precursor gene of HiPV lacks an AUG initiation codon at the expected position and the upstream sequence of the gene is predicted to form several stem-loop structures, suggesting that the precursor is produced by internal ribosome entry site (IRES) mediated-translation, as occurs in Plutia stali intestine virus (PSIV). These characteristics of the HiPV genome are similar to those of a new group of RNA viruses consisting of Drosophila C virus (DCV), Rhopalosiphum padi virus (RhPV), and PSIV.

G alpha-q/11 protein plays a key role in insulin-induced glucose transport in 3T3-L1 adipocytes

We evaluated the role of the G alpha-q (Galphaq) subunit of heterotrimeric G proteins in the insulin signaling pathway leading to GLUT4 translocation. We inhibited endogenous Galphaq function by single cell microinjection of anti-Galphaq/11 antibody or RGS2 protein (a GAP protein for Galphaq), followed by immunostaining to assess GLUT4 translocation in 3T3-L1 adipocytes. Galphaq/11 antibody and RGS2 inhibited insulin-induced GLUT4 translocation by 60 or 75%, respectively, indicating that activated Galphaq is important for insulin-induced glucose transport. We then assessed the effect of overexpressing wild-type Galphaq (WT-Galphaq) or a constitutively active Galphaq mutant (Q209L-Galphaq) by using an adenovirus expression vector. In the basal state, Q209L-Galphaq expression stimulated 2-deoxy-D-glucose uptake and GLUT4 translocation to 70% of the maximal insulin effect. This effect of Q209L-Galphaq was inhibited by wortmannin, suggesting that it is phosphatidylinositol 3-kinase (PI3-kinase) dependent. We further show that Q209L-Galphaq stimulates PI3-kinase activity in p110alpha and p110gamma immunoprecipitates by 3- and 8-fold, respectively, whereas insulin stimulates this activity mostly in p110alpha by 10-fold. Nevertheless, only microinjection of anti-p110alpha (and not p110gamma) antibody inhibited both insulin- and Q209L-Galphaq-induced GLUT4 translocation, suggesting that the metabolic effects induced by Q209L-Galphaq are dependent on the p110alpha subunit of PI3-kinase. In summary, (i) Galphaq appears to play a necessary role in insulin-stimulated glucose transport, (ii) Galphaq action in the insulin signaling pathway is upstream of and dependent upon PI3-kinase, and (iii) Galphaq can transmit signals from the insulin receptor to the p110alpha subunit of PI3-kinase, which leads to GLUT4 translocation.

Immunohistochemical staining of DNA topoisomerase IIalpha in human gliomas

OBJECT

The enzyme DNA topoisomerase IIalpha (Topo IIalpha) was tested as a measure of cell proliferation in gliomas.

METHODS

Immunostaining for the Topo IIalpha and for the Ki-67 antigen (MIB-1 antibody) was performed in paraffin-embedded tissue sections obtained from 25 resected human gliomas. Additionally, cultured human glioma cells were subjected to simultaneous flow cytometry to determine Topo IIalpha and DNA content. Using flow cytometric analysis, the authors found that the Topo IIalpha antibody labeled cells in the S, G2, and M phases of the cell cycle and also those in some parts of the G0 and G1 phases. In histological sections, Topo IIalpha showed more distinct staining than MIB-1, particularly in older archival cases. The proliferative indices (PIs) based on cells staining for MIB-1 and Topo IIalpha correlated highly with one another (r = 0.96). The Topo IIalpha PI immunopositivity was seen in 4.07% of cells in the low-grade astrocytoma group, 11.97% in the anaplastic astrocytoma group, and 13.84% in the glioblastoma multiforme group, representing significant differences between low-grade astrocytoma and both anaplastic astrocytoma and glioblastoma. A Topo IIalpha PI less than 5% predicted longer patient survival (p = 0.003).

CONCLUSIONS

Immunostaining for Topo IIalpha represents a useful alternative to MIB-1 as a proliferative index in human gliomas.

The antihyperglycaemic blend effect of traditional chinese medicine byakko-ka-ninjin-to on alloxan and diabetic KK-CA(y) mice

The antihyperglycaemic interaction (blend effect) of component crude drugs included in a traditional Chinese prescription, Byakko-ka-ninjin-to (BN; consisted of five crude drugs, ginseng, anemarrhena,-licorice, gypsum and rice) was investigated using genetically obese diabetic KK-CA(y) mice and alloxan-diabetic mice. The water extract of ginseng, anemarrhena, licorice and gypsum when individually tested markedly lowered blood glucose levels in diabetic animals. Antihyperglycaemic effects of ginseng-anemarrhena and ginseng-licorice combinations were decreased compared with the respective individual-effects. Such decreased effects were partially reversed by adding gypsum or by substituting CaCl(2) for gypsum. The combination of D-O-ANa and glycyrrhizin, respectively the main constituents from ginseng and licorice, also demonstrated a decreased effect compared with the respective individual effects. The CaCl(2) at 0.5 mg/kg (i.p.) was sufficient to partially reverse these effects. These results indicate that antihyperglycaemic effects of BN depend on four crude drugs and Ca(2+) in the blend.

Saccharomyces cerevisiae putative G protein, Gtr1p, which forms complexes with itself and a novel protein designated as Gtr2p, negatively regulates the Ran/Gsp1p G protein cycle through Gtr2p

Prp20p and Rna1p are GDP/GTP exchanging and GTPase-activating factors of Gsp1p, respectively, and their mutations, prp20-1 and rna1-1, can both be suppressed by Saccharomyces cerevisiae gtr1-11. We found that gtr1-11 caused a single amino acid substitution in Gtr1p, forming S20L, which is a putative GDP-bound mutant protein, while Gtr1p has been reported to bind to GTP alone. Consistently, gtr1-S20N, another putative GDP-bound mutant, suppressed both prp20-1 and rna1-1. On the other hand, gtr1-Q65L, a putative GTP-bound mutant, was inhibitory to prp20-1 and rna1-1. Thus, the role that Gtr1p plays in vivo appears to depend upon the nucleotide bound to it. Our data suggested that the GTP-bound Gtr1p, but not the GDP-bound Gtr1p, interacts with itself through its C-terminal tail. S. cerevisiae possesses a novel gene, GTR2, which is homologous to GTR1. Gtr2p interacts with itself in the presence of Gtr1p. The disruption of GTR2 suppressed prp20-1 and abolished the inhibitory effect of gtr1-Q65L on prp20-1. This finding, taken together with the fact that Gtr1p-S20L is a putative, inactive GDP-bound mutant, implies that Gtr1p negatively regulates the Ran/Gsp1p GTPase cycle through Gtr2p.