Restoration of cellular function of mesenchymal stem cells from a hypophosphatasia patient.

Mesenchymal stem cells (MSCs) can differentiate into multiple cell lineages and are used for regenerative treatments for a variety of diseases. However, the patient's cells cannot be used to treat genetic diseases. Allogeneic cells can serve as an alternative but long-term survival is uncertain. Our experience of allo-transplantation to a patient with hypophosphatasia, which is caused by mutations of the tissue non-specific alkaline phosphatase (TNSALP) gene resulting in low serum alkaline phosphatase (ALP) activity and skeletal deformity, did not improve these clinical characteristics. Therefore, we sought to use autologous MSCs for the treatment of hypophosphatasia. MSCs derived from the patient's bone marrow had a similar profile when compared with well-reported MSCs. However, the MSCs had extremely low ALP activity and could not produce a mineralized bone matrix even under the osteogenic culture conditions. We therefore transduced a retroviral vector with TNSALP promoter-driven TNSALP gene in the MSCs. In the culture condition, the MSCs had about 7-fold higher ALP activity than did mock-transduced MSCs, and showed mineralization as well as bone-specific markers. Furthermore, the MSCs, but not mock-transduced MSCs, newly formed bone at the frequency of 50% in nude rats. Transplantation of the TNSALP-transduced autologous MSCs might become a new therapy for hypophosphatasia.

Are DNA ploidy and epidermal growth factor receptor prognostic factors for untreated ovarian cancer? A prospective study.

To identify prognostic factors for untreated ovarian cancer, DNA ploidy, proliferative index (P.I.) and epidermal growth factor receptor (EGFR) expression were analyzed in a prospective series of 40 patients with ovarian cancer and 7 patients with borderline malignant ovarian tumor followed up for 5 years or more (median, 77 months). The frequency of aneuploid cells was 53.8% (21/39) in ovarian cancer and 14.3% (1/7) in borderline malignancy. There was no significant association between DNA ploidy and the clinicopathologic findings, in which aneuploid ovarian cancer was more common among advanced tumors. The S-phase fraction and P.I. value were higher in the patients with aneuploid tumors (p = 0.076). EGFR expression was detected in 76.9% (30/39) of ovarian cancers and 42.9% (3/7) of borderline malignant ovarian tumors, and the mean EGFR level was 5.8 +/- 12.1 (range: 0-49.5) and 28.3 +/- 71.1 (range: 0-189.4) fmol/mg protein, respectively. There was no correlation between EGFR expression and DNA ploidy, P.I., and clinicopathologic findings analyzed. The 5-year survival rate in patients with aneuploid tumors was significantly worse in patients with ovarian cancer (p = 0.0165, log-rank test). No significant relationship was shown between P.I., EGFR expression, and 5-year survival. Cox multivariate analysis showed that DNA ploidy, P.I., and EGFR expression are not associated with the risk of death (p = 0.5917, p = 0.9924, and p = 0.6840, respectively), although clinical stage shows a significant relationship (p = 0.0027). Our data showed that DNA ploidy is significantly related to the prognosis by univariate analysis, but DNA ploidy, P.I., and EGFR expression were not independent prognostic factors for the untreated ovarian cancer.

Genomic diversity of Bartonella henselae isolates from domestic cats from Japan, the USA and France by pulsed-field gel electrophoresis.

The genomic DNA diversity of 27 Bartonella henselae and three B. clarridgeiae isolates from 18 domestic cats from Japan, the USA and France was investigated by pulsed-field gel electrophoresis (PFGE) with NotI, AscI and SmaI restriction enzymes. A great diversity of genomic patterns was found for all B. henselae, but none for B. clarridgeiae isolates. The DNA size of B. henselae and B. clarridgeiae isolates were 1.7-2.9 and 1.7Mbp, respectively. All 13 Japanese cat isolates were identified as B. henselae type I. Furthermore, three of the four Japanese cats harbored genetically different B. henselae type I isolates, suggesting for the first time co-infection with various type I isolates. One French cat and one American cat were co-infected with B. henselae and B. clarridgeiae. B. henselae type I and type II were mainly grouped in two different clusters by PFGE using SmaI endonuclease in the dendrogram.

Prevalence of Bartonella species and 16s rRNA gene types of Bartonella henselae from domestic cats in Thailand.

Prevalence of Bartonella infection among 275 cats in 9 sites from 4 geographical regions (northern area: Chiang Mai; central area: Kanchanaburi, Ratchaburi, and Bangkok; northeastern area: Khon Kaen, Roi Et, Ubon Ratcharthani, and Nakhonratchasima; southern area: Songkhla) of Thailand was investigated. Overall, Bartonella species were isolated from 27.6% (76 of 275) of the cats. The isolation rate varied from 12.8% (5 of 39) in Songkhla (southern area) to 50.0% (26 of 52) in Khon Kaen (northeastern area). Bartonella henselae and B. clarridgeiae were isolated from 82.9% (63 of 76) and 11.8% (9 of 76) of the Bartonella-positive cats, respectively. Coinfection with both species was found in 5.3% (4 of 76) of the bacteremic cats. Of the 67 bacteremic cats from which B. henselae was isolated, 48 (71.6%) and 13 (19.4%) were infected with only Type I and Type II, respectively. Coinfection with both types was observed in 9.0% (6 of 67) of the B. henselae-positive cats. To our knowledge, this is the first report on the presence of Bartonella infection in domestic cats from Thailand, which constitute a large reservoir of Bartonella infection in this country.

Seroprevalence of Bartonella henselae and Toxoplasma gondii among healthy individuals in Thailand.

The seroprevalence of Bartonella henselae and Toxoplasma gondii among apparently healthy individuals, mainly blood donors, in Thailand was investigated by an indirect fluorescent antibody technique and by a latex agglutination test, respectively. Of 163 serum samples examined, 9 (5.5%) were found to be positive for B. henselae-IgG, 2 (1.2%) for B. henselae-IgM, and 5 (3.1%) for the T. gondii antibody. No significant difference was observed between male and female samples in the serological test with either B. henselae or T. gondii. The age of individuals with B. henselae-IgG was distributed from the 20s to the 70s, and B. henselae-IgM was found in the individuals of the 30s and 60s. The age of T. gondii positive samples ranged from the 20s to the 60s. In this study, the prevalence of B. henselae infection among healthy individuals in Thailand was serologically demonstrated for the first time.

Prospective analysis of DNA ploidy, proliferative index and epidermal growth factor receptor as prognostic factors for pretreated uterine cancer.

For the purpose of identifying prognostic factors for pretreated uterine cancer, DNA ploidy, proliferative index (P.I.) and epidermal growth factor receptor (EGFR) expression were analyzed in a large prospective series of 76 cervical cancer and 64 endometrial cancer patients observed for 5 years or more (median 76 months). The frequency of aneuploid cells was 62.0% (44/71) in cervical cancer and 16.7% (10/60) in endometrial cancer. There was no association between DNA ploidy and the clinicopathological findings without clinical stage, in which aneuploid cervical and endometrial cancers were significantly more common among advanced tumors (cervical: p<0. 05, endometrial: p<0.01). The P.I. was significantly higher in the patients with aneuploid tumors (cervical: p<0.05, endometrial p<0. 01). EGFR expression was detected in 56.6% (30/53) in cervical cancer and 59.6% (34/57) in endometrial cancer, and the mean EGFR level was 17.8+/-37.7 and 9.5+/-42.5 fmol/mg. protein, respectively. There was no correlation between EGFR expression and DNA ploidy, P.I. and clinicopathological findings analyzed. Five-year survival rate in patients with aneuploid tumors tended to have a worse outcome in cervical cancer cases (p=0.1003, log-rank test), and was significantly worse in endometrial cancer (p=0.0048, log-rank test). No significant relationship was noted between P.I., EGFR expression and 5-year survival. Cox multivariate analysis showed that DNA ploidy, P.I., and EGFR expression are not association with the risk of death. Our data showed neither DNA ploidy, P.I. nor EGFR expression were independent prognostic factors for pretreated uterine cancer.

Prevalence of Bartonella henselae, Bartonella clarridgeiae and the 16S rRNA gene types of Bartonella henselae among pet cats in Japan.

The authors investigated bacteriologically the prevalence of Bartonella infection among 690 pet cats derived from 10 private animal hospitals in six cities (Sapporo, Hokkaido Prefecture; Sendai, Miyagi Prefecture; Joetsu, Niigata Prefecture; Fujisawa, Kanagawa Prefecutre; Kyoto, Kyoto Prefecture; Sanda, Hyogo Prefecutre) and 4 counties (Mishima, Osaka Prefecture; Hikawa, Shimane Prefecture; Aira, Kagoshima Prefecture; Shimajiri, Okinawa Prefecture) located from the north to the south of Japan. Bartonella species were isolated from 7.2% (50/690) of all the cats examined. No Bartonella species were isolated from the cats in Sapporo or Sendai. The isolation rate varied from 2% in Joetsu and Sanda to 20% in Shimajiri. Bartonella clarridgeiae was isolated from two of 50 cats in Kyoto, three of 50 in Mishima and one of 50 in Shimajiri, but not in cats from the other cities or counties. Though the cats of Joetsu, Fujisawa, Kyoto, Sanda, Aira and Shimajiri were infected with either B. henselae or B. clarridgeiae, one of eight infected cats in Mishima was harboring both Bartonella species. Type I of 16S rRNA gene was the predominant type among the isolates of B. henselae, but only one isolate derived from Shimajiri was found to be of type II. Prevalence of B. clarridgeiae and the 16S rRNA gene type of B. henselae among cats in Japan was demonstrated for the first time in this investigation.

Three cases of cat scratch disease diagnosed by indirect immunofluorescence antibody assay and/or polymerase chain reaction of 16S rRNA gene of Bartonella henselae.

Three suspected cases of cat scratch disease were diagnosed by indirect immunofluorescence antibody assay and/or polymerase chain reaction. Patient 1 was a 10-year-old female who presented swelling of the right axillary [corrected] lymph nodes with pain and fever. She kept a kitten, and many scratches were observed on her both legs and dorsum manus. Antibody titers against Bartonella (B.) henselae were 1:32 for IgM 3 weeks after the onset of the symptoms and 1:64 for IgG 8 weeks after the onset. The DNA for 16S rRNA type I of B. henselae was detected from the blood sample obtained 3 weeks after the onset of symptoms by polymerase chain reaction for the first time in Japan. Patient 2 was a 22-year-old female veterinary student with a cat scratch at the bottom of her neck by a male kitten. She developed a papule at the scratch, slight fever, and neck pain. Although both Bartonella-specific IgG and IgM antibodies were negative before the scratch, the IgG antibody titer rose to 1:512 14 weeks after the onset. B. henselae was isolated from the kitten and its DNA found to be for 16S rRNA type I by PCR. Patient 3 was a 23-year-old female veterinary student with a cat scratch on her left forearm. A small reddish papule developed on the scratch, and she experienced swelling of the left axillary [corrected] lymph node and pain. Both the IgG and IgM antibodies against B. henselae were negative before the cat scratch, and the IgG titer rose significantly to 1:128 and 1:1,024 in 2 and 5 weeks, respectively, after the onset of the symptoms.

Changes in endothelium-derived vascular regulatory factors during dobutamine-stress-induced silent myocardial ischemia in patients with Kawasaki disease.

The changes in endothelium-derived vascular regulatory factors during dobutamine (DOB)-induced myocardial ischemia (MI) were investigated in 21 patients with Kawasaki disease aged from 11 months to 18 years. They were classified into an ischemia group (8 patients) and a non-ischemia group (13 patients) based on the results of 99mTc myocardial scintigraphy and DOB stress 99mTc myocardial scintigraphy. In the ischemia group, MI was relatively mild, because there were ischemic changes on the electrocardiogram and no significant symptoms during DOB stress. Catheters were positioned near the orifice of the coronary artery (Ao) and at the coronary sinus (CS). Hemodynamics and the blood concentrations of lactic acid and endothelin-1, as well as NO3-, 6-keto-prostaglandin F1alpha, and thromboxane B2, (which are inactive metabolites of nitric oxide, prostaglandin I2 and thromboxane A2, respectively), were measured at rest and after DOB stress (maximum dose: 30 microg x kg(-1) x min(-1)). The CS/Ao ratio was determined for all parameters. The rate-pressure product, an index of work load, and the cardiac index were significantly increased by DOB stress in both groups. Coronary angiography showed no vasospasm of the epicardial coronary arteries before or after DOB stress in either group. The plasma concentrations of endothelin-1 and 6-keto-prostaglandin F1alpha were significantly increased after DOB stress in the ischemia group, but the serum concentration of NO did not increase. The lack of an increase in NO production during DOB stress may have contributed to the worsening of MI in patients with Kawasaki disease.

Cloning and functional analysis of anti-double strand DNA IgG autoantibodies using the phage-display method.

To examine the relationship between pathophysiological effects and molecular features of anti-double-stranded (ds)DNA autoantibodies (Abs), we isolated anti-dsDNA Ab fragments by using the phage-display method. Fd ç and light-chain DNA were PCR amplified from peripheral blood lymphocytes of a patient with systemic lupus erythematosus (SLE), complicated with lupus nephritis. They were then inserted into a phagemid vector, pComb3-H. We generated eight Fab fragments that specifically bound to solid-phase DNA. The Fab clones stained positively using Crithidia luciliae, indicating that they were anti-dsDNA antibodies. Nucleotide sequences of VH of Fab clones were very similar and appeared to be derived from VH26 germline gene. Differences in the activities of anti-dsDNA Ab of the Fab clones may be ascribed to the diversity of VL. Fab fragments with anti-dsDNA Ab activities exhibited a positive charge on isoelectric focusing, consistent with pathogenic features. Our results indicate that anti-dsDNA Ab Fab fragments obtained by the phage-display method in the present study may possess molecular and functional characteristics of pathogenic anti-dsDNA autoAbs in SLE.

Pathogenicity of Mycobacterium avium complex serovar 9 isolated from painted quail (Excalfactoria chinensis).

Avian tuberculosis accompanied with many tubercular lesions in the liver and spleen was found in a painted quail at a zoological garden in Japan. Mycobacterium avium complex (MAC) serovar 9 without insertion sequence of IS901 was isolated from the liver (1.3 x 10(8) CFU/g), oviduct (9.4 x 10(7) CFU/g), and intestine (1.5 x 10(5) CFU/g). The isolates were inoculated intravenously to chickens. The inoculated chickens showed clinical symptoms of avian tuberculosis. Birds are susceptible to MAC serovar 9 without IS901.

[Isolation of Legionella and free-living amoebae at hot spring spas in Kanagawa, Japan].

Microbiological contamination of hot spring bath water is a public health concern. A province-wide survey was carried out to determine the extent and distribution of both Legionella and free-living amoebae contamination. Among 30 samples of hot spring bath from 12 sites in Kanagawa, Japan, L. pneumophila was detected in 21 water samples from 11 sites, ranging from 10(1)-10(3) CFU/100 ml. Serogroups 3, 5 and 6 of L. pneumophila were predominantly isolated from the samples. Naegleria (46.7%), Platyamoeba (33.3%), Acanthamoeba (10.0%) and 2 other genera of free-living amoebae were detected in 22 samples from 11 sites. One or more genera of host amoebae of Legionella occurred in 17 samples (56.7%) from 9 sites. Another thing to be noted is that 13 water samples contained N. lovaniensis. Although N. lovaniensis is nonpathogenic, it is considered an indicator organism for places that are suitable for the growth of N. fowleri, a causative agent of primary amoebic meningoencephalitis in man.

[Occurrence of free-living amoebae and Legionella in whirlpool bathes].

Occurrence of both Legionella species and free-living amoebae were surveyed in whirlpool bathes installed in 11 private houses, 8 public bathes and 13 spas. Free-living amoebae that are known to be the hosts of Legionella were isolated from 24 out of 32 water samples (75%). Single Legionella species, L. pneumophila, with different serogroups (SG) predominantly SG3 (18.3%), SG5 (23.7%) and SG6 (15.8%), were isolated from 21 damples, ranging from 10(1) to 10(4) CFU/100 ml. Further studies were conducted for 10 consecutive weeks to monitor the occurrence of both free-living amoebae and Legionella in the whirlpool bathes of 4 private houses. Free-living amoebae, such as Hartmannella and Vexillifera, and L. pneumophila SG1, SG3, SG4, SG5 and SG6 were consistently isolated from all the water samples throughout the monitoring periods. Bath basins in which Hartmennella and Vannella were isolated tended to harbor large number of Legionella. Management practices such as frequent washing filter elements and/or frequent addition of tap water to bath basins is highly recommended to reduce microbial contaminants.

[Experimental infection of Naegleria fowleri in mice].

Ten SPF mice (ddY, 4w-old, female) were infected by nasal instillation with an isolate of Naegleria fowleri that was first isolated from a patient with primary amoebic meningoencephalitis (PAM) in Japan. Of these mice, 2 showed clinical signs typical for PAM on the 4th day. On the next day, 5 mice became very ill and remained immobile; their movement and response to painful stimuli diminished progressively. All the infected mice were then examined histopathologically on the same day regardless of their clinical signs. Pathological changes due to invasion and/or proliferation of amoebae were observed in 5 mice with clinical signs. Swelling of the nasal mucosa and ulcerated nasal epithelium with inflammatory cells were observed. Proliferation of amoebae was detected to a lesser extent in nasal cavity including mucous membrane and nasal epithelium. Olfactory lobes and arteriolar hemisphere were necrotic with haemorrhage and filled with amoebae. From these findings the pathogenicity of the isolate was confirmed to develop PAM in experimental animals. It was also observed that the olfactory neuroepithelium was the route of invasion in PAM due to N. fowleri and consequently migration occurred through olfactory lobes into the cerebrum.

Analysis of kappa light chain contribution to anti-DNA antibody activity of a human VH4-21-encoded monoclonal antibody (NE-1) by antibody-phage display technique.

Although contribution of light chain to DNA reactivity of some murine anti-DNA antibodies (Abs) has been demonstrated, similar studies on human anti-DNA Abs are limited. To investigate this contribution, we reproduced Fab molecules on the surface of phages from a human B cell line producing IgM anti-DNA monoclonal Ab (NE-1) by an Ab-phage display technique. Expressed Fab molecules (p4-1 clone) were similar to the parental mAb in their binding activities and idiotypic expression. We constructed a light chain shuffled library containing Vkappa genes derived from peripheral blood lymphocytes of a patient with systemic lupus erythematosus (SLE) in combination with the NE-1 heavy chain gene. After panning to ss- or dsDNA, 7 Fab-phage clones which showed significant bindings to ss- or dsDNA were isolated. Many other Fab-phage clones from the library did not bind to ss- nor dsDNA. Sequence analysis revealed that light chains of the 7 clones are derived from diverse Vkappa germline genes including rarely used ones such as the L5 and A30. Most of the Vk germline genes have been used for previously reported anti-DNA antibodies. These findings suggest that diverse Vkappa genes can pair with the NE-1 heavy chain for anti-DNA Ab activity. In addition, kappa light chains seem to modulate DNA binding activities in various ways.

Carbachol inhibition of Ca2+ currents in ventricular cells obtained from neonatal and adult rats.

We investigated the postnatal developmental changes produced by the muscarinic receptor agonist, carbachol, on the L-type Ca2+ current (ICa(L)) in neonatal (aged 5 to 7 days) and adult (aged 2 to 5 months) rat ventricular cells by using the whole-cell voltage clamp technique. Carbachol inhibited the isoproterenol-stimulated ICa(L). The maximal inhibition was 89.3 +/- 4.8% (n = 5) in neonatal cells and 17.7 +/- 7.7% (n = 9) in adult cells. Carbachol inhibited the forskolin-stimulated ICa(L) to almost same extent as the isoproterenol-stimulated ICa(L). In the cells pretreated with pertussis toxin, carbachol failed to inhibit the isoproterenol-stimulated ICa(L), indicating that carbachol produced its effect via a pertussis toxin-sensitive G-protein pathway. The effects of carbachol in adult cells became more pronounced, increasing from 17.7% to 54.8% (n = 11), with the addition of the synthetic inhibitory G-protein alpha subunit (Gi alpha) (1 microM) to the reaction. Conversely, the alpha subunit of another pertussis toxin-sensitive synthetic G-protein (G(o) alpha, 1 microM) failed to mimic the effect of Gi alpha. These results suggest that, in rat ventricular cells, (1) the action of carbachol on ICa(L) showed a marked decrease during development; (2) the decrease in the effect of carbachol in adult cells is in part due to a decrease in the activity of pertussis toxin-sensitive G protein, especially Gi alpha.

Seroprevalence of Bartonella henselae and Toxoplasma gondii infections among pet cats in Kanagawa and Saitama Prefectures.

Seroprevalence of Bartonella henselae and Toxoplasma gondii was investigated among 471 pet cats obtained from seven private animal hospitals in Kanagawa and Saitama Prefectures during the period from May 1994 to June 1995. 'Furthermore, 67 randomly selected from the 471 serum samples were examined for the feline immunodeficiency virus (FIV) antibody and feline leukemia virus (FeLV) antigen. The antibody to B. henselae was examined by an indirect immunofluorescent antibody test. T. gondii, FIV and FeLV infections in cats were detected with respective commercial kits. Of the cat serum samples tested, 43 (9.1%) were found to be seropositive for B. henselae and 41 (8.7%) for T. gondii. The B. henselae-positive rate (12.9%) of male cats was significantly higher than that (5.2%) of female cats. On the other hand, T. gondii-positive rate was 9.1% in male and 8.7% in female cats and there was no significant difference in the positivity between sexes. The positive rate in each hospital varied from 0 to 19.5% for B. henselae and 4.9 to 18.8% for T. gondii. The ages of B. henselae- and T. gondii-positive cats were distributed from < 1-year-old to 14-year-old and the seropositivity increased with age of cats. Of the 67 cat serum samples, 16 and 6 cases were positive for FIV and FeLV, respectively. There was no relationship between these viral and B. henselae infections in cats.

Oxygen-bridged dinuclear ruthenium amine complex specifically inhibits Ca2+ uptake into mitochondria in vitro and in situ in single cardiac myocytes.

Ruthenium red is a well known inhibitor of Ca2+ uptake into mitochondria in vitro. However, its utility as an inhibitor of Ca2+ uptake into mitochondria in vivo or in situ in intact cells is limited because of its inhibitory effects on sarcoplasmic reticulum Ca2+ release channel and other cellular processes. We have synthesized a ruthenium derivative and found it to be an oxygen-bridged dinuclear ruthenium amine complex. It has the same chemical structure as Ru360 reported previously (Emerson, J., Clarke, M. J., Ying, W-L., and Sanadi, D. R. (1993) J. Am. Chem. Soc. 115, 11799-11805). Ru360 has been shown to be a potent inhibitor of Ca2+-stimulated respiration of liver mitochondria in vitro. However, the specificity of Ru360 on Ca2+ uptake into mitochondria in vitro or in intact cells has not been determined. The present study reports in detail the potency, the effectiveness, and the mechanism of inhibition of mitochondrial Ca2+ uptake by Ru360 and its specificity in vitro in isolated mitochondria and in situ in isolated cardiac myocytes. Ru360 was more potent (IC50 = 0.184 nM) than ruthenium red (IC50 = 6.85 nM) in inhibiting Ca2+ uptake into mitochondria. 103Ru360 was found to bind to isolated mitochondria with high affinity (Kd = 0.34 nM, Bmax = 80 fmol/mg of mitochondrial protein). The IC50 of 103Ru360 for the inhibition of Ca2+ uptake into mitochondria was also 0.2 nM, indicating that saturation of a specific binding site is responsible for the inhibition of Ca2+ uptake. Ru360, as high as 10 microM, produced no effect on sarcoplasmic reticulum Ca2+ uptake or release, sarcolemmal Na+/Ca2+ exchange, actomyosin ATPase activity, L-type Ca2+ channel current, cytosolic Ca2+ transients, or cell shortening. 103Ru360 was taken up by isolated myocytes in a time-dependent biphasic manner. Ru360 (10 microM) applied outside intact voltage-clamped ventricular myocytes prevented Ca2+ uptake into mitochondria in situ where the cells were progressively loaded with Ca2+ via sarcolemmal Na+/Ca2+ exchange by depolarization to +110 mV. We conclude that Ru360 specifically blocks Ca2+ uptake into mitochondria and can be used in intact cells.

Production of bacteriocin-like-substance by Listeria innocua against Listeria monocytogenes.

Cultures and culture filtrates of 129 Listeria innocua strains were examined for inhibitory activity against 18 strains of Listeria monocytogenes. Of the strains examined, 114 (88.4%) cultures and 126 (97.7%) culture filtrates had an inhibitory activity against strains of L. monocytogenes and most filtrates were sensitive to trypsin treatment. The authors concluded that most L. innocua strains produce a trypsin sensitive bacteriocin-like substance against L. monocytogenes.

Inhibition of Ca2+ current in neonatal and adult rat ventricular myocytes by the tyrosine kinase inhibitor, genistein.

Yokoshiki et al. (Yokoshiki, H., Sumii, K., Sperelakis, N., 1996. Inhibition of L-type calcium current in rat ventricular cells by the tyrosine kinase inhibitor, genistein and its inactive analog, daidzein. J. Mol. Cell. Cardiol. 28, 807-814) reported that genistein and daidzein inhibited L-type Ca2+ current (I(Ca)(L)) in young rat ventricular cells. Therefore, we investigated the developmental differences in the effect of genistein, an inhibitor of tyrosine kinases, on I(Ca)(L) in freshly-isolated neonatal (3-7 days) and adult (2-5 months) rat ventricular myocytes using whole-cell voltage clamp and single-channel recordings (cell-attached configuration). For whole-cell voltage clamp, I(Ca)(L) was measured as the peak inward current at a test potential of +10 mV by applying a 300 ms pulse from a holding potential of -40 mV. To isolate I(Ca(L), the pipette solution was Cs+-rich and the bath solution was Na+-, K+-free. Ca2+ (1.8 mM) was used as charge carrier. Bath application of 100 microM genistein (sufficient for maximal effect) decreased the basal I(Ca)(L) by 43.3% (n = 27) in neonatal cells and by 30.6% (n = 14) in adult cells (P < 0.05). In the current/voltage relationships, the potential of peak I(Ca)(L) was shifted to the right by genistein by 8.6 mV in neonatal and by 9.3 mV in adult cells. Genistein produced a shift of the steady-state inactivation curve (to the left) in neonatal cells (from -16.0 +/- 3.9 mV to -26.1 +/- 4.2 mV; P < 0.05) and in adult cells (-15.9 +/- 3.2 mV to -22.9 +/- 3.3 mV; P < 0.05); the slope factor was not affected. For single-channel recordings in cell-attached patches, Ca2+ currents were evoked by applying a 150 ms pulse from a holding potential of -40 mV to a test potential of 0 mV. The pipette solution contained 110 mM Ba2+ (as charge carrier), and the bath solution contained 150 mM K+ (to bring resting potential to near zero). Genistein (50 microM) decreased the open probability of the channels from 2.8% to 0.75% (P < 0.05) in absence of Bay K 8644, and from 24% to 7.9% (P < 0.05) in presence of Bay K 8644; the mean open time and the slope conductance of the currents were not affected. In conclusion, (1) genistein inhibits the basal I(Ca)(L) in rat ventricular cells and (2) the inhibition of I(Ca)(L) by genistein is greater in immature cells than in adult cells.